sectional design standard for rigid organic printed...

IPC-2222

Sectional Design Standard for

Rigid Organic Printed Boards

ASSOCIATION CONNECTINGELECTRONICS INDUSTRIES

2215 Sanders Road, Northbrook, IL 60062-6135Tel. 847.509.9700 Fax 847.509.9798

www.ipc.org

ANSI/IPC-2222February 1998 A standard developed by IPC

Supersedes IPC-D-275September 1991

The Principles ofStandardization

In May 1995 the IPC’s Technical Activities Executive Committee adopted Principles ofStandardization as a guiding principle of IPC’s standardization efforts.

Standards Should:• Show relationship to DFM & DFE• Minimize time to market• Contain simple (simplified) language• Just include spec information• Focus on end product performance• Include a feedback system on use and

problems for future improvement

Standards Should Not:• Inhibit innovation• Increase time-to-market• Keep people out• Increase cycle time• Tell you how to make something• Contain anything that cannot be

defended with data

Notice IPC Standards and Publications are designed to serve the public interest through eliminatingmisunderstandings between manufacturers and purchasers, facilitating interchangeability andimprovement of products, and assisting the purchaser in selecting and obtaining with minimumdelay the proper product for his particular need. Existence of such Standards and Publicationsshall not in any respect preclude any member or nonmember of IPC from manufacturing or sell-ing products not conforming to such Standards and Publication, nor shall the existence of suchStandards and Publications preclude their voluntary use by those other than IPC members,whether the standard is to be used either domestically or internationally.

Recommended Standards and Publications are adopted by IPC without regard to whether theiradoption may involve patents on articles, materials, or processes. By such action, IPC doesnot assume any liability to any patent owner, nor do they assume any obligation whatever toparties adopting the Recommended Standard or Publication. Users are also wholly responsiblefor protecting themselves against all claims of liabilities for patent infringement.

IPC PositionStatement onSpecificationRevision Change

It is the position of IPC’s Technical Activities Executive Committee (TAEC) that the use andimplementation of IPC publications is voluntary and is part of a relationship entered into bycustomer and supplier. When an IPC standard/guideline is updated and a new revision is pub-lished, it is the opinion of the TAEC that the use of the new revision as part of an existingrelationship is not automatic unless required by the contract. The TAEC recommends the useof the lastest revision. Adopted October 6. 1998

Why is therea charge forthis standard?

Your purchase of this document contributes to the ongoing development of new and updatedindustry standards. Standards allow manufacturers, customers, and suppliers to understand oneanother better. Standards allow manufacturers greater efficiencies when they can set up theirprocesses to meet industry standards, allowing them to offer their customers lower costs.

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©Copyright 1998. IPC, Northbrook, Illinois. All rights reserved under both international and Pan-American copyright conventions. Anycopying, scanning or other reproduction of these materials without the prior written consent of the copyright holder is strictly prohibited andconstitutes infringement under the Copyright Law of the United States.

ANSI/IPC-2222

Sectional Design

Standard for Rigid

Organic Printed Boards

Developed by the IPC-D-275 Task Group (D-31b) of the Rigid PrintedBoard Committee (D-30) of IPC

Users of this standard are encouraged to participate in the

development of future revisions.

Contact:

IPC2215 Sanders RoadNorthbrook, Illinois60062-6135Tel 847 509.9700Fax 847 509.9798


APPROVED JANUARY 7, 1999 BY

AMERICAN NATIONAL STANDARDS INSTITUTE

FOREWORD

This standard is intended to provide information on the detailed requirements for organic rigid printed board design. Allaspects and details of the design requirements are addressed to the extent that they can be applied to the unique require-ments of those designs that use organic rigid (reinforced) materials or organic materials in combination with inorganic mate-rials (metal, glass, ceramic, etc.) to provide the structure for mounting and interconnecting electronic, electromechanical, andmechanical components.

The information contained herein is intended to supplement generic engineering considerations and design requirementsidentified in IPC-2221. When coupled with the engineering design input, the complete disclosure should facilitate the appro-priate selection process of the materials and the detailed organic rigid structure fabrication technology necessary to meet theengineering design objectives.

The selected component mounting and interconnecting technology for the printed board should be commensurate with therequirements provided and the specific focus of this sectional document.

IPC’s documentation strategy is to provide distinct documents that focus on specific aspect of electronic packaging issues.In this regard document sets are used to provide the total information related to a particular electronic packaging topic. Adocument set is identified by a four digit number that ends in zero (0).

Included in the set is the generic information which is contained in the first document of the set and identified by the fourdigit set number. The generic standard is supplemented by one or many sectional documents each of which provide specificfocus on one aspect of the topic or the technology selected. The designer of the printed board, needs as a minimum, thegeneric, the sectional of the chosen technology, the generic engineering considerations, and the engineering description ofthe final product.

Failure to have all information available prior to starting a design may result in a product that is difficult to manufacture orexceeds the cost predictions or expectations of the printed board.

As technology changes, specific focus standards will be updated, or new focus standards added to the document set. TheIPC invites input on the effectiveness of the documentation and encourages user response through completion of ‘‘Sugges-tions for Improvement’’ forms located at the end of each document

HIERARCHY OF IPC DESIGN SPECIFICATIONS(2220 SERIES)

IPC-2222RIGID

IPC-2223FLEX

IPC-2224PCMCIA

IPC-2225MCM-L

IPC-2226HDIS

IPC-2227DISCRETE WIRE

IPC-2221GENERIC DESIGN

AcknowledgmentAny Standard involving a complex technology draws material from a vast number of sources. While the principal membersof the IPC-D-275 Task Group (D-31b) of the Rigid Printed Board Committee (D-30) are shown below, it is not possible toinclude all of those who assisted in the evolution of this Standard. To each of them, the members of the IPC extend theirgratitude.

Rigid Printed BoardCommittee

IPC-D-275 Task Group(D-31b)

Technical Liaison of theIPC Board of Directors

ChairmanBob NevesMicrotek Lab

ChairmanLionel FullwoodWong’s Kong King Int’l

Ronald UnderwoodCircuit Center

IPC-D-275 Task Group

Richard Altenhofen, Motorola GSTGDaniel Arnold, EMD Associates Inc.Lance A. Auer, Hughes Missile

Systems CompanyNanci J. Baggett, Printed Circuit

ResourcesSteve Bakke, Alliant Techsystems

Inc.Karl J. Bates, Lucent TechnologiesRobert E. Beauchamp, Lockheed

Martin Missiles & SpaceFrank Belisle, Sundstrand AerospaceDavid W. Bittle, Raytheon Aircraft

CompanyDaniel L. Botts, Hughes Training,

Inc.John Bourque, Shure Brothers Inc.Scott A. Bowles, Sovereign Circuits

Inc.Stephen G. Bradley, CAL

CorporationJim Brock, SCI Systems Inc.Ignatius Chong, CelesticaDavid J. Corbett, DSCCBrian Crowley, Hewlett Packard

LaboratoriesGeorgia DeGrandis, ABB Ceag

Power Supplies Inc.Yong Deng, Owens-Corning

Fiberglass Corp.Michele J. DiFranza, The Mitre Corp.C. Don. Dupriest, Lockheed Martin

Vought SystemsTheodore Edwards, Honeywell Inc.Will J. Edwards, Lucent Technologies

Inc.Werner Engelmaier, Engelmaier

Associates, Inc.Thomas R. Etheridge, McDonnell

Douglas Aerospace

Joe Fjelstad, Tessera Inc.Martin G. Freedman, Amp Inc.Lionel Fullwood, Wong’s Kong King

Int’lMahendra S. Gandhi, Hughes Aircraft

Co.Paul Grande, Jr., U.S. NavyMichael R. Green, Lockheed Martin

Missiles & SpaceLyle F. Harford, Texas Instruments

Inc.Andrew J. Heidelberg, Micron

Custom Mfg. Services Inc.Ralph J. Hersey, Ralph Hersey &

AssociatesPhillip E. Hinton, Hinton -PWB-

EngineeringOctavian Iordache, Circo Craft Co.

Inc.Don Jensen, Endicott Research GroupArturo J. Jordan, Pollak Trnsprtatn

Electrnics DivJohn A. Kelly, Motorola GSTGTherese Kokocinski, Northrop

Grumman CorporationStephen Korchynsky, Lockheed

Martin Federal SystemsGeorge T. Kotecki, Northrop

Grumman CorporationThomas E. Kurtz, Hughes Defense

CommunicationsClifford H. Lamson, Harris Corp.Bonnie Lauch, Honeywell Inc.Stan C. Mackzum, Ericsson Inc.James F. Maguire, Boeing Defense &

Space GroupDavid J. Malanchuk, Eastman Kodak

Co. KADWesley R. Malewicz, Siemens

Medical Systems Inc.

Susan Mansilla, Robisan LaboratoryInc.

Lester Mielczarek, CAE ElectronicsLtd.

Kelly J. Miller, CAE Electronics Ltd.John H. Morton, Lockheed Martin

Federal SystemsKarl B. Mueller, Hughes Aircraft Co.Joseph L. Mulcahy, Methode

Electronics Inc. EastBenny Nilsson, Ericsson Telecom ABR. Bruce. Officer, Sanders, A

Lockheed Martin Co.Scott S. Opperhauser, Trace

Laboratories - EastJohn Papinko, Gulton Data SystemsRon Payne, Primex AerospaceRichard Peyton, Lockheed Martin

AstronauticsLarry L. Puckett, Sandia National

Labs AlbuquerquePaul J. Quinn, Lockheed Martin

Missiles & SpaceKurt Ravenfeld, Lockheed Martin

CorporationRandy R. Reed, Merix CorporationBruce C. Rietdorf, Hughes Defense

CommunicationsJerald G. Rosser, Hughes Missile

Systems CompanyVincent J. Ruggeri, Raytheon

CompanyDon W. Rumps, Lucent Technologies

Inc.Robert Russell, Texas Instruments

Inc.Merlyn L. Seltzer, Hughes Delco

Systems OperationsNusrat Sherali, IBM Corp.Lowell Sherman, DSCC

February 1998 IPC-2222

iii

Rae Shyne, Prototron Circuits Inc.Grant (Rick) W. Smedley, III, Printed

Circuit ResourcesE. Lon. Smith, Lucent Technologies

Inc.Joseph J. Sniezek, IBM Corp./

Endicott Electronic PaWilliam F. Spurny, AlliedSignal

AerospaceRobert J. St. Pierre, New England

Laminates

Thomas K. Stewart, Speedy CircuitsGil Theroux, Honeywell Inc.Ronald E. Thompson, U.S. NavyMax E. Thorson, Compaq Computer

CorporationLutz E. Treutler, Fachverband

Elektronik DesignRobert Vanech, Northrop Grumman

Norden Systems

Eric L. Vollmar, Methode ElectronicsInc.

Forrest L. Voss, RockwellInternational

Rich Warzecha, Advanced Flex Inc.Clark F. Webster, Computing Devices

InternationalDavid A. White, Input/Output Inc.

IPC-2222 February 1998

iv

Table of Contents

1.0 SCOPE .................................................................... 11.1 Purpose................................................................. 1

1.2 Document Hierarchy............................................ 1

1.3 Presentation .......................................................... 1

1.4 Interpretation ........................................................ 1

1.5 Classification of Products .................................... 1

1.5.1 Board Type........................................................... 1

1.6 Assembly Types ................................................... 1

2.0 APPLICABLE DOCUMENTS ................................... 12.1 Institute for Interconnecting and Packaging

Electronic Circuits (IPC) .................................... 1

2.2 Underwriters Laboratories ................................... 3

3.0 GENERAL REQUIREMENTS ................................... 33.1 Performance Requirements.................................. 3

4.0 MATERIALS .............................................................. 34.1 Material Selection ................................................ 3

4.2 Dielectric Base Materials (IncludingPrepregs and Adhesives)...................................... 3

4.2.1 Epoxy Laminates ................................................. 3

4.2.2 High-Temperature Laminates .............................. 3

4.2.3 Special Clad Materials......................................... 3

4.2.4 Other Laminates................................................... 3

4.3 Laminate Materials .............................................. 3

4.3.1 Measurement of Dielectric Thickness................. 3

4.3.2 Dielectric Thickness/Spacing............................... 4

4.3.3 Laminate Properties ............................................. 5

4.3.4 Prepreg ................................................................ 5

4.3.5 Single-Clad Laminates......................................... 5

4.3.6 Double-Clad Laminates ....................................... 5

4.3.7 Laminate Material................................................ 5

4.4 Conductive Materials......................................... 13

4.5 Organic Protective Coatings.............................. 13

4.6 Markings and Legends ...................................... 13

5.0 MECHANICAL/PHYSICAL PROPERTIES ............. 13

5.1 Fabrication Requirements .................................. 13

5.2 Product/Board Configuration............................. 13

5.2.1 Board Geometries .............................................. 13

5.2.2 Support ............................................................... 13

5.3 Assembly Requirements .................................... 13

5.3.1 Assembly and Test............................................. 14

5.4 Dimensioning Systems ...................................... 15

5.4.1 Grid Systems...................................................... 15

5.4.2 Profiles, Cutouts and Notches ........................... 15

6.0 ELECTRICAL PROPERTIES ................................. 16

7.0 THERMAL MANAGEMENT ................................... 16

8.0 COMPONENT AND ASSEMBLY ISSUES ............. 168.1 General Attachment Requirements.................... 16

8.1.1 Attachment of Wires/Leads to Terminals ......... 16

8.1.2 Board Extractors ................................................ 16

9.0 HOLE/INTERCONNECTIONS ................................ 169.1 General Requirements for Lands with Holes ... 16

9.1.1 Land Requirements ............................................ 16

9.1.2 Thermal Relief in Conductor Planes................. 16

9.1.3 Clearance Area in Planes................................... 17

9.1.4 Nonfunctional Lands.......................................... 18

9.1.5 Conductive Pattern Feature LocationTolerance ............................................................ 18

9.2 Holes .................................................................. 18

9.2.1 Unsupported Holes ........................................... 18

9.2.2 Plated-Through Holes ........................................ 19

9.2.3 Etchback............................................................. 19

9.3 Drill Size Recommendations forPrinted Boards.................................................... 20

10.0 GENERAL CIRCUIT FEATUREREQUIREMENTS ................................................. 20

INDEX .......................................................................... 23

10.1 Conductor Characteristics.................................. 20

10.1.1 Edge Spacing ..................................................... 20

10.1.2 Balanced Conductors ......................................... 21

10.1.3 Flush Conductors for Rotating or SlidingContacts.............................................................. 21

10.1.4 Metallic Finishes for Flush Conductors............ 21

10.2 Land Characteristics .......................................... 21

10.2.1 Lands for Interfacial Connection Vias .............. 21

10.2.2 Offset Lands....................................................... 21

10.2.3 Conductive Pattern Feature LocationTolerance ............................................................ 21

10.2.4 Nonfunctional Lands.......................................... 21

10.3 Large Conductive Areas .................................... 21

11.0 DOCUMENTATION ............................................... 22

11.1 Filled Holes........................................................ 22

11.2 Nonfunctional Holes .......................................... 22

12.0 QUALITY ASSURANCE ..................................... 22

Figures

Figure 1-1 Electrical assembly types ................................. 2

Figure 4-1 Dielectric layer thickness measurement........... 4


v

Figure 4-2 Designer / end user materials selectionmap ................................................................. 11

Figure 5-1 Panel borders ................................................. 14

Figure 5-2 Scoring parameters ........................................ 14

Figure 5-3 Breakaway tabs .............................................. 15

Figure 8-1 Permanent board extractor............................. 16

Figure 8-2 External board extractor ................................. 16

Figure 9-1 Clearance area in planes, mm....................... 17

Figure 9-2 Foil web size................................................... 18

Figure 9-3 Lead-to-hole clearance................................... 19

Figure 10-1A Typical flush circuit ......................................... 21

Figure 10-1B Surface flushness conditions.......................... 22

Figure 10-2 Cross-hatched large conductive layerswith isothermal conductors............................. 22

Tables

Table 4-1 Clad Laminate Maximum OperatingTemperatures........................................................ 4

Table 4-2 FR-4 Copper Clad Laminate ConstructionSelection Guide .................................................... 6

Table 4-3 High TG FR-4 Copper Clad LaminateConstruction Selection Guide............................... 7

Table 4-4 Cyanate Ester (170 to 250° TG) CopperClad Laminate Construction Selection Guide ...... 8

Table 4-5 BT Copper Clad Laminate ConstructionSelection Guide .................................................... 9

Table 4-6 Polyimide Copper Clad LaminateConstruction Selection Guide............................. 10

Table 5-1 Panel Size to Manufacturing OperationRelationships ...................................................... 14

Table 5-2 Standard Scoring Parameters............................ 14

Table 5-3 Tolerance of Profiles, Cutouts, Notches, andKeying Slots, as Machined, mm ........................ 15

Table 9-1 Feature Location Tolerances (Lands,Conductor Pattern, etc.) (Diameter TruePosition).............................................................. 18

Table 9-2 Minimum Unsupported Holes ToleranceRange (Difference between high and lowhole size limits)................................................... 18

Table 9-3 Plated-Through Hole Diameter to LeadDiameter Relationships ...................................... 20

Table 9-4 Plated-Through Hole Aspect Ratio..................... 20

Table 9-5 Minimum Plated-Through Hole DiameterTolerance Range, mm(Difference between high and low holesize limits)........................................................... 20

Table 9-6 Minimum Drilled Hole Size for Plated-ThroughHole Vias ............................................................ 20

Table 9-7 Drill Size Recommendations Related toMaximum Board Thickness................................ 20

Table 10-1 Surface Flushness Requirements ...................... 21


vi


Sectional Design Standard forRigid Organic Printed Boards

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1.0 SCOPE

This standard establishes the specific requirements fordesign of rigid organic printed boards and other formscomponent mounting and interconnecting structures.organic materials may be homogeneous, reinforced, or uin combination with inorganic materials; the interconnetions may be single, double, or multilayered.

1.1 Purpose The requirements contained herein aintended to establish specific design details thatshall beused in conjunction with IPC-2221 (see 2.0) to produdetailed designs intended to mount and attach passiveactive components.

The components may be through-hole, surface mount,pitch, ultra-fine pitch, array mounting or unpackaged bdie. The materials may be any combination able to perfothe physical, thermal, environmental, and electronic fution.

1.2 Document Hierarchy Document hierarchyshall bein accordance with the generic standard IPC-2221.

1.3 Presentation Presentationshall be in accordancewith the generic standard IPC-2221.

1.4 Interpretation Interpretationshall be in accordancewith the generic standard IPC-2221.

1.5 Classification of Products Classification of Productsshall be in accordance with the generic standard IPC-2and as follows:

1.5.1 Board Type This standard provides design infomation for different board types. Board types are classifias:

Type 1 — Single-Sided Printed BoardType 2 — Double-Sided Printed BoardType 3 — Multilayer Board without Blind or Buried ViasType 4 — Multilayer Board with Blind and/or Buried ViaType 5 — Multilayer Metal-Core Board without Blind o

Buried ViasType 6 — Multilayer Metal-Core Board with Blind and/o

Buried Vias

1.6 Assembly Types A type designation signifies furthesophistication describing whether components are mouon one or both sides of the packaging and interconnec

1. IPC, 2215 Sanders Road, Northbrook, IL 60062

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structure. Type 1 defines an assembly that has componmounted on only one side; Type 2 is an assembly wcomponents on both sides. Type 2, Class A is not recomended.

Figure 1-1 shows the relationship of two types of asseblies.

The need to apply certain design concepts should depon the complexity and precision required to produce a pticular land pattern or P&I structure. Any design class mbe applied to any of the end-product equipment categortherefore, a moderate complexity (Type 1B) would deficomponents mounted on one side (all surface mounted)when used in a Class 2 product (dedicated service electics) is referred to as Type 1B, Class 2. The produdescribed as a Type 1B, Class 2 might be used in any ofend-use applications; the selection of class being depenon the requirements of the customers using the applicat

2.0 APPLICABLE DOCUMENTS

The following documents form a part of this documentthe extent specified herein. If a conflict of requiremenexist between IPC-2222 and those listed below, IPC-22takes precedence.

The revision of the document in effect at the time of solictation shall take precedence.

2.1 Institute for Interconnecting and Packaging Elec-tronic Circuits (IPC)1

IPC-EG-140 Specification For Finished Fabric WoveFrom ‘‘E’’ Glass for Printed Board

IPC-MF-150 Metal Foil for Printed Wiring Applications

IPC-CF-152 Composite Metallic Materials Specificatiofor Printed Wiring Boards

IPC-D-279 Design Guidelines for Reliable Surface MounTechnology Printed Board Assemblies

IPC-TM-650 Test Methods Manual

Method 2.1.1 Microsectioning

Method 2.1.6 Thickness of Glass Fabric

IPC-SM-782 Surface Mount Design and Land PatterStandard

1


IPC-013-1-1

Figure 1-1 Electrical assembly types

PLCCCHIP COMPONENT

DIP

PLCC CHIPCOMPONENT

SOIC

PLCCCHIP COMPONENT SOIC

PLCC

2-Sided Thru-hole (NOT RECOMMENDED)

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CHIPCOMPONENT

SOIC

CHIPCOMPONENT SOIC

DIP

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SOIC

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Type 2

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Wire bond ortab IC chipattachment

UFPT PKG.(selectively attached)

SOIC

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PLCC CHIPCOMPONENT

DIP

SOLDER PASTE

CSMT/TH

FPT PKG.

FLIPCHIP

BGA

Components (mounted) on only one side of the board

Components (mounted) on both sides of the board

Y Z&Similar, with additional component types(not shown) as described in the legend.

X Y& See Legend

Class AClass BClass CClass XClass YClass Z

= Through-hole component mounting only= Surface mounted components only= Simplistic through-hole and surface mounting intermixed assembly= Complex intermixed assembly, through-hole, surface mount, fine pitch BGA= Complex intermixed assembly, through-hole, surface mount, ultra fine pitch, chip scale= Complex intermixed assembly, through-hole, ultra fine pitch, COB, flip chip, TAB

PLCC

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IPC-2221 Generic Standard on Printed Board Design

IPC-4101 Laminate/Prepreg Materials Standard foPrinted Boards

IPC-6012 Qualification and Performance Specification foRigid Printed Boards

2.2 Underwriters Laboratories2

UL 746E Standard Polymeric Materials, Materials UsedPrinted Wiring Boards

3.0 GENERAL REQUIREMENTS

General requirementsshall be in accordance with thegeneric standards IPC-2221.

3.1 Performance Requirements Finished rigid printedboards shall meet the performance requirements of IP6012.

4.0 MATERIALS

4.1 Material Selection Material Selectionshall be inaccordance with the generic standard IPC-2221.

4.2 Dielectric Base Materials (Including Prepregs andAdhesives) Dielectric base materialsshall be in accor-dance with the generic standard IPC-2221 and the folloing:

4.2.1 Epoxy Laminates Epoxies are the most commoresin materials which are combined with glass cloth to pduce laminates. When compared to other laminate matals, epoxies offer advantages in availability and relatiease in processing. The many different types and blendepoxies exhibit a wide range of selection for usage or sdering processes; epoxies with a Tg (glass transition tem-perature) from 110 to 120°C up to 180 to 190°C are avaable from most laminate suppliers with some of the moused in the 135 to 145°C range.

4.2.2 High-Temperature Laminates High temperaturelaminates include those made from resins such as EpoCyanate Ester, Triazine blends and polyimide. High teperature resin laminates offer the advantages of increachemical and temperature resistance. Disadvantainclude the need for specialized processing and higmaterial cost.

4.2.3 Special Clad Materials The use of surface mountechnology may require the use of special clad materiwhen coefficient of thermal expansion matching is criticaExamples of these special materials are copper-clad In

2. Underwriter’s Labs, 333 Pfingsten Avenue, Northbrook, IL 60062

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epoxy or polyimide with aramid fiber and polyimidequartz. The most common usage is for Class 3 boaalthough there may also be some application for ClassThese materials offer the advantages of performancespecialized applications; the need for unique processduring board fabrication is a disadvantage.

4.2.4 Other Laminates Laminates, such as paper-basephenolics etc., have acceptance in some consumer prodwhere the complexity is quite low due to lesser materand manufacturing costs. These materials are associwith very high volume products with lower performancrequirements than those usually associated with epoxy tlaminates.

4.3 Laminate Materials Laminate materialsshall be inaccordance with the generic standard IPC-2221 and aslows:

When metal clad, foil typeshall be as specified in IPC-MF-150. Unclad laminates without an adhesive, per IP4101 may be used as fillers in multilayer boards for dieletric spacing between layers.

When Underwriter’s Labs (UL) requirements are imposethe material used must be approved by UL for use asers in multilayer boards for dielectric spacing between laers. Printed boardsshall be fabricated from the laminatematerials specified in Table 4-1 or UL 746E.

The board designshall be such that internal temperaturrise due to current flow in the conductor, when added toother sources of heat at the conductor/laminate interfawill not result in an operating temperature in excess of thspecified for the laminate material. The values in Table 4are based on long term thermal aging tests by UL and mbe mandatory for designs to be used in UL approved pructs. Since heat dissipated by parts mounted on the bowill contribute local heating effects, the material selectioshall take this factor, plus the equipment’s general internrise temperature, plus the specified operating ambient tperature for the equipment into account. Hot spot tempeturesshall not exceed the temperatures specified in Ta4-1 for the laminate material selected. Materials us(copper-clad, prepreg, copper foil, heat sink, etc.)shall bespecified on the master drawing.

4.3.1 Measurement of Dielectric Thickness Dielectricthickness will vary across applications. Thicknessmechanical measurement is determined in accordanceIPC-TM-650, Method 2.1.6. Thickness by microsectio(view shown in Figure 4-1) is determined in accordanwith IPC-TM-650, Method 2.1.1. The dielectric thicknesis measured in accordance with Figure 4-1 and taken atclosest point between metal claddings.

3


Table 4-1 Clad Laminate Maximum Operating Temperatures 1

Designation DielectricThickness (min)

Temperature 4, 5, 6, 7

(max)NEMA IPC-4101

FR-4 21/24/25/27 0.1 mm 120°C

0.4 mm 130°C

FR-5 23 0.6 mm 140°C

1.4 mm 170°C

GPY 40/41/42 0.1 mm 140°C

1.6 mm 170°C

50/52 0.1 mm 120°C

0.4 mm 130°C

51/53/60 0.1 mm 140°C

1.6 mm 170°C

30/26 0.1 mm 120°C

0.4 mm 130°C

70/71 0.1 mm 140°C

0.4 mm 170°C1. Ambient temperature plus the temperature rise caused by current in the conductors and components.2. FR-4 laminates should not be combined in one board with GPY prepregs.3. When GPY laminates are combined in one board with FR-4 prepregs, the temperature shall be that specified for the FR-4 materials.4. A multilayer board shall be limited to a maximum operating temperature for the total dielectric thickness shown above.5. For reinforcement/resin combinations not specifically shown above, the maximum operating temperature should be close to that of a listed combination with

the same resin.6. Other materials in the same classification with higher operating temperatures may be available.7. Dielectric thickness smaller than those shown above may be temperature rated by UL for certain laminate manufacturers.

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4.3.2 Dielectric Thickness/Spacing The minimumdielectric thickness/spacingshall be specified on the master drawing. If the minimum dielectric spacing and thnumber of reinforcing layers are not specified, the mimum dielectric spacing is 0.09 mm and the numberreinforcing layers may be selected by the supplier.

4

Note: Minimum dielectric spacing may be specified to0.03 mm; however, low-profile copper foils should be usand the voltages employed should be taken into consation so as not to cause breakdown between layers.IPC-2221 for more information on electrical conducspacing.

IPC-2221-4-1

Figure 4-1 Dielectric layer thickness measurement

Metal Cladding

Metal Cladding

(Microsection)

Average of Peakto Valley Thickness(Equivalent to Weight)

DielectricMaximumThicknessTypical ofMechanicalThicknessMeasurements

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ly-ithicalsol-ted.

asmilare T

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4.3.3 Laminate Properties

4.3.3.1 Thickness Tolerance When specifying overallmultilayer board thickness, and individual dielectric thicness between layers, it is important to recognize the effof accumulated tolerances of individual dielectrics onoverall thickness of completed boards.

4.3.3.2 Resin Content Laminates are a composite oresin and glass cloth or other reinforcement. As laminthicknesses increase, heavier glass cloths or reinforcemare used, and the percentages of resin (resin contdecrease. Laminates with higher resin content tend to hhigher coefficients of thermal expansion and lower dimesional stability. However, if resin contents are too loweave exposure and measling may result. The glasresin ratio of a laminate also has a direct effect on dieltric constant.

4.3.4 Prepreg

4.3.4.1 Epoxy Low Tg epoxies are the most commoresin materials which are combined with glass clothother reinforcement and semi-cured to produce preprEpoxy prepregs will produce acceptable product for Cl1, 2, and 3 multilayer printed boards. Because of differchemical processing requirements for various resin stems, it is preferred to use like resins for laminates aprepregs when constructing a multilayer printed board.

4.3.4.2 High-Temperature Prepregs High temperatureprepregs include those made from resins such as EpCyanate ester, Triazine blends and polyimide. High teperature prepregs may be used for specialized Class 2tilayer printed board applications, but are more commoused for Class 3 multilayer printed boards.

4.3.4.3 Glass Style A variety of glass cloth styles aravailable for prepregs (see IPC-EG-140). The glass cselection is dependent upon dielectric thickness and toance required, circuit filling needs, and electrical requiments of the dielectric.

4.3.4.4 Electrical Requirements For multilayer printedboards which have controlled impedance requirements,dielectric constant of the laminated prepreg must be ctrolled. Because dielectric constant is a function of tresin/glass or other reinforcement ratio, prepreg styshould be chosen so that after lamination, the proretained resin content is achieved in order to arrive atspecified dielectric constant.

4.3.5 Single-Clad Laminates Laminates with foil on oneside may be used as an outer layer or internal layer omultilayer printed board, as appropriate.

s

tst)e

o-

.

t-

y,

l-

-

e-

r

4.3.6 Double-Clad Laminates Laminates with foil onboth sides may be used to provide either internal or exnal conductive layers. Double-clad laminate is specifiedboth industry and IPC specifications by the dielectric seration between the conductive layers as shown in Fig4-1. Tables 4-2 through 4-6 provide information on tproperties of finished bare laminates for different prepconstructions. To establish final laminate thickness wcopper, add 35 µm for each oz. of copper on the lamin

4.3.7 Laminate Material Laminate materialsshall bespecified on the drawing. See Figure 4-2 for a mappingthe recommended material selection process.

Materials are generally purchased to meet the requiremof IPC-4101. A typical material code designation of a spcific material would be L21 1500 C1/C1 A1A. When thfinished product requires Underwriters Labs (UL) approvmaterialshall be ordered to meet UL specifications.

4.3.7.1 Typical Material Designation The first threecharacters of the code designate the type of material.indicates laminate material. ‘‘P’’ indicates prepreg mater

• ‘‘L21’’— Woven ‘‘E’’ glass fabric impregnated withflame resistant, epoxy resin of a type that is a majoritydifunctional resin. Small amounts of multifunctional resor novalacs are sometimes added to enhance the phyproperties. This is the standard NEMA FR-4 grade mafactured by most laminators since the 1950s. The gtransition temperature (Tg) is normally from 110 to 150°Cbut not specified.

• ‘‘L25’’— Woven ‘‘E’’ glass fabric impregnated withflame resistant epoxy resin which is commonly a pofunctional type resin. This resin may be modified wother epoxies to increase the high temperature physproperties. This material may be used where repeateddering operations to replace components are anticipaThe Tg is specified to be from 150 to 200°C.

• ‘‘L26’’— This grade is similar to L25 except that theepoxy resin is modified with non-epoxy resins suchcyanate esters and/or bismaleimides. The uses are sibut where higher temperatures may be anticipated. Thg

is specified to be from 170 to 220°C.

• ‘‘L40’’— Woven ‘‘E’’ glass fabric impregnated with poly-imide resin. Introduced in the 1960s for high temperatoperating environments such as missile engine contrthe resin has been supplied primarily from one Europsource. The natural color is opaque brown. The Tg is nor-mally from 200 to 250° but not specified.

• ‘‘L42’’— This grade is similar to L40 except that thepolyimide resin may be modified with nonpolyimide reins. The primary purpose of the modifications areimprove the producibility of the printed board. The appcations are similar. The Tg is specified as from 200 to250°C.

5


IPC-Slash Sheet #1

Table 4-2 FR-4 Copper Clad Laminate Construction Selection Guide

Sla

sh

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ee

t 1

FR-4

CO

PP

ER

CLA

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CH

EM

ME

AS

LE

AV

AIL

CO

ST

FL

AT

SM

OO

TH

DR

ILL

FR

-4 0

10

.07

mm

FR

-4 0

00

.05

mm

10

80

60

4.2

5

64

4.1

5

72

4.1

0

57

4.3

0

70

4.0

8

56

4.3

0

59

4.2

5

53

4.4

0

51

4.4

5

54

4.4

0

50

4.5

0

40

4.7

5

50

4.5

0

47

4.5

5

52

4.4

47

4.6

55

4.6

47

4.6

47

4.6

41

4.7

46

4.8

48

4.5

43

4.7

43

4.8

46

4.5

40

4.7

47

4.6

42

4.7

41

4.7

44

4.7

42

4.7

42

4.7

FR

-4 0

20

.08

mm

2x

10

6

FR

-4 0

30

.11

mm

2x

10

6

FR

-4 0

40

.11

mm

21

13

10

6

0.1

4m

m1

06

/21

13

FR

-4 0

5

0.1

3m

m2

x1

08

0F

R-4

06

0.1

3m

m2

11

6F

R-4

07

0.1

6m

m1

06

/21

16

FR

-4 0

8

0.1

6m

m1

08

0/2

11

3F

R-4

09

0.1

8m

m2

x2

11

3F

R-4

10

0.1

8m

m7

62

8F

R-4

11

0.2

1m

m2

11

3/2

11

6F

R-4

12

0.2

1m

m2

x2

11

6F

R-4

13

0.2

5m

m2

x2

11

6

0.2

6m

m7

62

8/1

08

0

FR

-4 1

4

0.2

6m

m2

x1

08

0/2

11

6

FR

-4 1

5

0.3

1m

m2

x1

08

0/7

62

8

FR

-4 1

6

0.3

2m

m7

62

8/2

11

6

FR

-4 1

7

0.3

7m

m2

x7

62

8

FR

-4 1

8

0.3

7m

m2

x2

11

3/7

62

8

FR

-4 1

9

0.4

3m

m2

x2

11

6/7

62

8

FR

-4 2

0

0.4

3m

m2

x7

62

8/1

08

0

FR

-4 2

1

0.4

8m

m2

x7

62

8/2

11

6

FR

-4 2

2

0.5

1m

m2

x1

08

0/2

x7

62

8

FR

-4 2

3

0.5

3m

m3

x7

62

8

FR

-4 2

4

0.6

4m

m2

x2

11

6/2

x7

62

8

FR

-4 2

5

0.6

1m

m3

x7

62

8/1

08

0

FR

-4 2

6

0.7

4m

m4

x7

62

8

FR

-4 2

7

0.7

4m

m2

x2

11

3/3

x7

62

8

FR

-4 2

8

0.7

5m

m4

x7

62

8/1

08

0

FR

-4 2

9

1.5

2m

m8

x7

62

8

FR

-4 3

0

FR

-4 3

1

Bett

er

+B

lan

kW

ors

e

6


IPC-Slash Sheet #2

Table 4-3 High T G FR-4 Copper Clad Laminate Construction Selection Guide

Sla

sh

Sh

ee

t 2

HIG

H T

G F

R-4

CO

PP

ER

CLA

D L

AM

INA

TE

CO

NS

TR

UC

TIO

N S

ELE

CT

ION

R

EG

#T

HIC

KN

ES

SC

ON

ST

RU

CT

ION

% R

CD

KD

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DS

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TE

TH

ICK

TO

L

CH

EM

ME

AS

LE

AV

AIL

CO

ST

FL

AT

SM

OO

TH

DR

ILL

HF

R-4

01

0.0

7m

m

HF

R-4

00

0.0

5m

m

10

80

60

4.2

5

64

4.1

5

72

4.1

0

57

4.3

0

70

4.0

8

56

4.3

0

59

4.2

5

53

4.4

0

51

4.4

5

54

4.4

0

50

4.5

0

40

4.7

5

50

4.5

0

47

4.5

5

52

4.4

47

4.6

55

4.6

47

4.6

47

4.6

41

4.7

46

4.8

48

4.5

43

4.7

43

4.8

46

4.5

40

4.7

47

4.6

42

4.7

41

4.7

44

4.7

42

4.7

42

4.7

HF

R-4

02

0.0

8m

m2

x1

06

HF

R-4

03

0.1

1m

m2

x1

06

HF

R-4

04

0.1

1m

m2

11

3

10

6

0.1

4m

m1

06

/21

13

HF

R-4

05

0.1

3m

m2

x1

08

0H

FR

-4 0

6

0.1

3m

m2

11

6H

FR

-4 0

7

0.1

6m

m1

06

/21

16

HF

R-4

08

0.1

6m

m1

08

0/2

11

3H

FR

-4 0

9

0.1

8m

m2

x2

11

3H

FR

-4 1

0

0.1

8m

m7

62

8H

FR

-4 1

1

0.2

1m

m2

11

3/2

11

6H

FR

-4 1

2

0.2

1m

m2

x2

11

6H

FR

-4 1

3

0.2

5m

m2

x2

11

6

0.2

6m

m7

62

8/1

08

0

HF

R-4

14

0.2

6m

m2

x1

08

0/2

11

6

HF

R-4

15

0.3

1m

m2

x1

08

0/7

62

8

HF

R-4

16

0.3

2m

m7

62

8/2

11

6

HF

R-4

17

0.3

7m

m2

x7

62

8

HF

R-4

18

0.3

7m

m2

x2

11

3/7

62

8

HF

R-4

19

0.4

3m

m2

x2

11

6/7

62

8

HF

R-4

20

0.4

3m

m2

x7

62

8/1

08

0

HF

R-4

21

0.4

8m

m2

x7

62

8/2

11

6

HF

R-4

22

0.5

1m

m2

x1

08

0/2

x7

62

8

HF

R-4

23

0.5

3m

m3

x7

62

8

HF

R-4

24

0.6

4m

m2

x2

11

6/2

x7

62

8

HF

R-4

25

0.6

1m

m3

x7

62

8/1

08

0

HF

R-4

26

0.7

4m

m4

x7

62

8

HF

R-4

27

0.7

4m

m2

x2

11

3/3

x7

62

8

HF

R-4

28

0.7

5m

m4

x7

62

8/1

08

0

HF

R-4

29

1.5

2m

m8

x7

62

8

HF

R-4

30

HF

R-4

31

Bett

er

+B

lan

kW

ors

e

7


IPC-Slash Sheet #3

Table 4-4 Cyanate Ester (170 to 250° T G) Copper Clad Laminate Construction Selection Guide

Sla

sh

Sh

ee

t 3

CY

AN

ATE

EST

ER (1

70 t

o 23

0° T

G) C

OPP

ER C

LAD

LA

MIN

ATE

CO

NST

RUC

TIO

N S

ELEC

TIO

N G

UID

ER

EG

#T

HIC

KN

ES

SC

ON

ST

RU

CT

ION

% R

CD

KD

K.

TO

L.

DS

Z C

TE

TH

ICK

TO

L

CH

EM

ME

AS

LE

AV

AIL

CO

ST

FL

AT

SM

OO

TH

DR

ILL

CE

01

0.0

7m

m1

08

0

CE

00

0.0

5m

m1

06

70

3.1

0

CE

02

0.0

8m

m2

x1

06

62

60

3.3

7

68

3.2

8

54

3.7

0

56

3.5

8

52

3.7

1

51

3.8

0

51

3.8

0

50

3.7

8

40

4.0

8

48

3.8

5

44

3.9

0

52

3.7

1

45

3.9

3

54

3.7

0

45

3.9

3

44

3.9

0

38

4.1

5

44

3.9

0

39

4.1

1

39

4.1

1

41

4.0

5

38

4.1

5

44

3.9

0

41

4.0

5

38

4.1

5

41

4.0

5

38

4.1

5

40

4.0

8

44

3.9

0

52

3.7

1

3.4

4

CE

03

0.1

1m

m2

x1

06

CE

04

0.1

1m

m2

11

3

CE

05

0.1

4m

m1

06

/21

13

CE

06

0.1

3m

m2

x1

08

0

CE

07

0.1

3m

m2

11

6

CE

08

0.1

6m

m1

06

/21

16

CE

09

0.1

6m

m1

08

0/2

11

3

CE

10

0.1

8m

m2

x2

11

3

CE

11

0.1

8m

m7

62

8

CE

12

0.2

1m

m2

11

3/2

11

6

CE

13

0.2

1m

m2

x2

11

6

CE

14

0.2

5m

m2

x2

11

6

CE

15

0.2

6m

m7

62

8/1

08

0

CE

16

0.2

6m

m2

x1

08

0/2

11

6

CE

17

0.3

1m

m2

x1

08

0/7

62

8

CE

18

0.3

2m

m7

62

8/2

11

6

CE

19

0.3

7m

m2

x7

62

8

CE

20

0.3

7m

m2

x2

11

3/7

62

8

CE

21

0.4

3m

m2

x2

11

6/7

62

8

CE

22

0.4

3m

m2

x7

62

8/1

08

0

CE

23

0.4

8m

m2

x7

62

8/2

11

6

CE

24

0.5

1m

m2

x1

08

0/2

x7

62

8

CE

25

0.5

3m

m3

x7

62

8

CE

26

0.6

4m

m2

x2

11

6/2

x7

62

8

CE

27

0.6

1m

m3

x7

62

8/1

08

0

CE

28

0.7

4m

m4

x7

62

8

CE

29

0.7

4m

m2

x2

11

3/3

x7

62

8

CE

30

0.7

5m

m4

x7

62

8/1

08

0

CE

31

1.5

2m

m8

x7

62

8

Bett

er

+B

lan

kW

ors

e

8


IPC-Slash Sheet #4

Table 4-5 BT Copper Clad Laminate Construction Selection Guide

Sla

sh

Sh

ee

t 4

BT

CO

PP

ER

CLA

D L

AM

INA

TE

CO

NS

TR

UC

TIO

N S

ELE

CT

ION

GU

IDE

RE

G#

TH

ICK

NE

SS

CO

NS

TR

UC

TIO

N%

RC

DK

DK

. T

OL

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SZ

CT

ET

HIC

K

TO

L

CH

EM

ME

AS

LE

AV

AIL

CO

ST

FL

AT

SM

OO

TH

DR

ILL

BT

01

0.0

7m

m

BT

00

0.0

5m

m

10

80

60

3.7

3

64

3.6

5

72

3.5

5

57

3.8

1

70

3.6

0

56

3.8

3

59

3.7

5

53

3.9

2

51

3.9

7

54

3.8

9

50

4.0

0

40

4.3

0

50

4.0

0

47

4.1

0

52

4.0

47

4.1

55

3.9

47

4.1

47

4.1

41

4.3

46

4.2

48

4.1

43

4.3

43

4.3

46

4.2

40

4.3

47

4.1

42

4.3

41

4.3

44

4.2

42

4.3

42

4.3

BT

02

0.0

8m

m2

x1

06

BT

03

0.1

1m

m2

x1

06

BT

04

0.1

1m

m2

11

3

10

6

0.1

4m

m1

06

/21

13

BT

05

0.1

3m

m2

x1

08

0B

T 0

6

0.1

3m

m2

11

6B

T 0

7

0.1

6m

m1

06

/21

16

BT

08

0.1

6m

m1

08

0/2

11

3B

T 0

9

0.1

8m

m2

x2

11

3B

T 1

0

0.1

8m

m7

62

8B

T 1

1

0.2

1m

m2

11

3/2

11

6B

T 1

2

0.2

1m

m2

x2

11

6B

T 1

3

0.2

5m

m2

x2

11

6

0.2

6m

m7

62

8/1

08

0

BT

14

0.2

6m

m2

x1

08

0/2

11

6

BT

15

0.3

1m

m2

x1

08

0/7

62

8

BT

16

0.3

2m

m7

62

8/2

11

6

BT

17

0.3

7m

m2

x7

62

8

BT

18

0.3

7m

m2

x2

11

3/7

62

8

BT

19

0.4

3m

m2

x2

11

6/7

62

8

BT

20

0.4

3m

m2

x7

62

8/1

08

0

BT

21

0.4

8m

m2

x7

62

8/2

11

6

BT

22

0.5

1m

m2

x1

08

0/2

x7

62

8

BT

23

0.5

3m

m3

x7

62

8

BT

24

0.6

4m

m2

x2

11

6/2

x7

62

8

BT

25

0.6

1m

m3

x7

62

8/1

08

0

BT

26

0.7

4m

m4

x7

62

8

BT

27

0.7

4m

m2

x2

11

3/3

x7

62

8

BT

28

0.7

5m

m4

x7

62

8/1

08

0

BT

29

1.5

2m

m8

x7

62

8

BT

30

BT

31

Bett

er

+B

lan

kW

ors

e

9


IPC-Slash Sheet #5

Table 4-6 Polyimide Copper Clad Laminate Construction Selection Guide

Sla

sh

Sh

ee

t 5

PO

LYIM

IDE C

OP

PE

R C

LAD

LA

MIN

AT

E C

ON

ST

RU

CT

ION

SE

LEC

TIO

N G

UID

ER

EG

#T

HIC

KN

ES

SC

ON

ST

RU

CT

ION

% R

CD

KD

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10

TRATES

Blends

PTFE

PTFE,

ms, Quartzal Core

d Epoxy, CE

d Epoxy,

CEM-3

ultifunctionalodified Epoxy

February1998

IPC

-222211

IPC

-2222-4-2

Figure

4-2D

esigner/

enduser

materials

selectionm

ap

DESIGN CRITERIA APPLICABLE SUBS

Better ThermalPerformance Than FR-4

Better Electricals?(High Speed, CTI)

XY DimensionalConstraints (SMT)?

Greater Than 10 Layers?

Punched PlatedThrough-Holes

Single Sided

GreaterThan200˚ Tg?

High CTI?

HighHumidity?

LeadlessOr VeryComplexLeaded?

Z AxisConcerns?

NO

YESPl, Pl Blends - CE, CE

Modified Epoxy

Modified Epoxy, CE,

Modified Epoxy, CE, Pl, Pl BlendsAramid Based SysteBased Systems, Met

Multi-Epoxy, Modifie

Multi-Epoxy, ModifieCE, Pl

FR-4

CEM-3, CRM-5, FR-6

FR-6, CRM-5, CEM-1,FR-2, XXXPFR-4 Type:• Bifunctional • M• Tertafunctional • M

FR-6 / CRM-5

YES

NO

YES

YES

NO

YES

NO

YES

NO

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

DESIGNER / END USERMATERIALS SELECTION MAP

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• ‘‘L41’’— This grade is similar to L40 except that theresin chemistry may be altered. The applications are simlar but higher operating temperature limits are possibThe Tg is specified as above 250°C.

• ‘‘L30’’— Woven ‘‘E’’ glass fabric impregnated with BTresin. This resin is a mixture of bismaleimides and triaine. Its uses are similar to those for L25. The Tg is nor-mally from 165 to 180°C. Hot strength retention shoulnot be confused with flame resistance. Hot strength retetion allows the board to operate at higher temperaturwithout losing electrical and mechanical propertieFlame resistance implies self-extinguishing properties.

4.3.7.2 Dielectric Thickness The next four numbers ofthe code (1500) designates the nominal dielectric thickne

The nominal base thickness is identified by four digits thindicate the thickness of the base material in thousandthsa millimeter (i.e., 1500 represents a nominal base thickneof 1.5 mm). When English units are specified, the four diits indicate thickness in ten-thousandths of an inch [i.e0590 = 0.059 in]. The overall nominal thickness does ninclude the metal cladding. The nominal thickness (i.e1500) stands alone with no tolerance. The drawing titblock tolerance of three decimal places does not appLater in the code is a designation that applies a toleranto the nominal thickness per industry standards. Whatenominal thickness (typically 1.5 mm) is required, the coresponding number is inserted.

4.3.7.3 Copper Foil Designation The type and nominalweight of the copper foil cladding is identified by the nexfive characters of the code (i.e., C1/C1). The first anfourth characters of this designator will consist of the folowing letters to indicate the type of copper foil cladding

A — Copper, rolled, wrought (IPC-MF-150, Class 5).

B — Copper, rolled (treated).

C — Copper, drum side out, electrodeposited (IPC-M150, Class 1).

D — Copper, drum side out, (double treated) electrodepoited.

G — Copper, high ductility electrodeposited (IPC-MF150), Class 2).

H — Copper, high temperature elongation (IPC-MF-15Class 3).

J — Copper, annealed electrodeposited (IPC-MF-15Class 4).

K — Copper, light cold rolled-wrought (IPC-MF-150,Class 6).

L — Copper, annealed-wrought (IPC-MF-150, Class 7).

O — Unclad

M — Copper, as rolled-wrought-low temperature (IPCMF-150, Class 8).

12

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-

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N — Nickel

U — Aluminum

V — Copper-Invar-Copper (IPC-CF-152)

Type C or H copper foil claddings are most often used.

The second and the fifth characters of this designatorindicate the nominal copper foil weight in ounces psquare foot (oz/ft2). The two indicators, which are separated by a slash (third character), will use the actual nubers for copper foil 1 oz/ft2 or over, and the following let-ters for copper foil under 1 oz/ft2.

E — 0.125 oz/ft2

Q — 0.25 oz/ft2

T — 0.375 oz/ft2

H — 0.50 oz/ft2

M — 0.75 oz/ft2

O — Unclad

X — For any weight or thickness not expressed (e.g.,oz. copper foil) by a single digit designator. Foexample, ‘‘C1/C1’’ designates 1 oz/ft

2

copper, drumside out, on one side and 1 oz/ft2 copper drum sideout, on the other side. The slash should be consered to be the base laminate.

Base materials that are unclad on both sides would beignated 00/00.

This designation does not mean the total amount of copthat should be on the surface after processing (see I2221).

Copper foils can be specified in foil weights from 0.1257 oz/ft2.

‘‘CX/00’’ is the requirement for single-sided boards.

‘‘CX/CX’’ is the requirement for double-sided boards.

4.3.7.4 Pit Designation The thirteenth character (‘‘A’’)in the material specification code denotes the class ofand dents allowed in the copper foil. Class of foil indentions is determined by the total amount and individulength of the pits and dents. A ‘‘pit’’ is a disruption or voiin the surface of the copper, and must be within the limitions allowed by the applicable procurement document‘‘dent’’ is a depression in the surface of the base laminaand under pressure during lamination, the dent is traferred to the surface of the copper. There are five allowadesignations: ‘‘A’’, ‘‘B’’, ‘‘C’’, ‘‘D’’, and ‘‘X’’ (see IPC-4101).

• ‘‘A’’ designation [29 points per 300 mm x 300 mm areais adequate down to 0.25 mm conductors and spaces

• ‘‘B’’ designation [5 points per 300 mm x 300 mm areashould be considered below 0.25 mm conductors aspaces.

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• ‘‘C’’ designation [17 points per 300 mm x 300 mm area]

• ‘‘D’’ designation [0 points per 300 mm x 300 mm area]

• ‘‘X’’ designation’’ shall be as agreed between user ansupplier (IPC-4101).

4.3.7.5 Thickness Class Tolerance Designation Thedesignation ‘‘1’’ is a thickness class tolerance specificatiofor the base laminate (see table below).

• If the board is going to mount on standoffs and/or ththickness is of no importance, Class 1 should be spefied.

• If the board is required to plug into an edge connectoClass 2 or even Class 3 should be considered. The fiished board thickness includes the nominal laminathickness and the class tolerance, plus all the additionplating thicknesses added together.

4.3.7.6 Bow and Twist Designation The final characterin the material specification code (for the laminate materionly, not the final etched board) is a ‘‘bow and twist’specification per the following. These values apply only tsheet sizes as manufactured, and to cut pieces having eidimension no less than 460 mm.

• For nominal thicknesses not shown, the bow or twist fothe next lower thickness shown applies.

• A board that has both dimensions less than 460 mm geerally requires an ‘‘A’’ specification.

• A board that has both dimensions greater than 460 mrequires a ‘‘B’’ specification.

• Boards that have one dimension less than 460 mm athe other greater than 460 mm, and have gold fingersthe long dimension, require a ‘‘B’’ specification.

• Class ‘‘X’’ indicates no bow or twist requirement andmay be used only for single-sided boards. But in the caof bow, the percentage is stated in terms of the laterdimension (length or width); in the case of twist, the pecentage is stated in terms of the dimension from one coner to the diagonally opposite corner.

If the specification does not call out any class tolerancethe loosest requirements are assumed.

4.4 Conductive Materials Conductive materialsshall bein accordance with the generic standard IPC-2221.

4.5 Organic Protective Coatings Organic protectivecoatingsshall be in accordance with the generic standarIPC-2221.

4.6 Markings and Legends Marking and legendsshallbe in accordance with the generic standard IPC-2221.

5.0 MECHANICAL/PHYSICAL PROPERTIES

5.1 Fabrication Requirements Fabrication requirementsshall be in accordance with the generic standard IPC-22and as follows:

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Typical maximum fabrication panel size limits for boaprocessing equipment are summarized in Table 5-1.

5.2 Product/Board Configuration Product/board con-figurationshall be in accordance with the generic standaIPC-2221 and as follows:

5.2.1 Board Geometries The following are consider-ations to be taken into account during the design oprinted board.

5.2.1.1 Borders and Spacing Borders and margins arcommonly employed by the printed board fabricator to pvide room for tooling features and other process confeatures (see Figure 5-1).

The size of such borders is usually in the range of 10 tomm. This is determined by also taking into accountoptimum number of boards per panel, obtaining optimplating across the panel (especially important for higdensity/fine line boards), etc.

When the printed boards are made using a print-and-procedure the border size may depend on the typeprinted board being made, i.e., double-sided printed botend to have smaller borders; multilayer printed boatend to have wider borders. Also, the size of the bordneed not be the same on all four sides of the panel.

The margins between boards on a panel also haveaccommodate the panel/board shearing, blanking and ring operations. Thus, their size is commonly chosen toeither 4.8, 5.0 and 6.5 mm or the nearest dimension sable to maintain the board features on the basic procesgrid.

5.2.1.2 Dimensional Aspect Ratio Board length towidth relationships should be kept as similar as possiLong narrow boards or unusually-shaped boards leadexcessive bowing/twisting. Dimensional instability, aassociated problems at all stages of fabrication, assemtest and system fixturing become factors in determinfinal board size.

5.2.2 Support Adequate mechanical support shouldprovided typically for at least two opposite edges ofprinted wiring assembly. The location and method of sport shall be such as to minimize shock and/or vibrationa level that will protect against fracturing or looseningconductor foil, or breaking of the components or compnent leads as a result of flexing the printed board assemwithin the tolerance of the applicable specification.

5.3 Assembly Requirements Assembly requirementsshall be in accordance with the generic standard IPC-2and as follows:

13


Table 5-1 Panel Size to Manufacturing Operation Relationships

Operation Typical Maximum Panel Size

Drill 460 mm x 610 mm

Scrub, deburr, and most conveyorized finishing equipment 610 mm x open

Plating equipment Custom sized, check with fabricator

Exposure equipment 610 mm x 610 mm

Routing equipment 460 mm x 610 mm

Screening equipment 510 mm x 760 mm

Bare board test 460 mm x 460mm

Laminating press size (based on 610 mm x 760 mm press with 50 mm open area onplated edges)

510 mm x 660 mm

Solder coating 460 mm x 610 mm

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5.3.1 Assembly and Test Palletization of parts is a standard process in many instances for both test and assemThis can be achieved using a number of different teniques. These include simple scoring, a combinationrouting and scoring, and a combination of routing plbreakaway.

Scoring is the machining of a shallow, precise V-groointo the top and bottom surfaces of the laminate. It is gerally accomplished using CNC equipment. As scoriallows the removal of rails and individual parts from a palet, positional accuracy is critical. See Table 5-2 and Fure 5-2 for some standard scoring parameters.

IPC-275-5-4

Figure 5-1 Panel borders

▼

▼

Panel Edge

Board Edge

▼▼ Tooling/pinning holes

14

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-

IPC-2222-5-2

Figure 5-2 Scoring parameters

A/2

E

BA

H

FC

D

G

CIRCUI

Table 5-2 Standard Scoring Parameters

DetailLetter Title Definition Attainable Tolerances

A Web The material remaining between the two (2) ‘V’ scores ona plane perpendicular to the printed board surface

± 80 µm

B Centrality The distance the center of a web is offset from truecenter within the printed board.

± 80 µm

C Blade offset The distance the top and bottom scoring blades areoffset from one another.

± 80 µm

D Score width The width of a score line at the surface of the printedboard

± 80 µm

E Cutter angle The total angle of a scoring blade. ± 2°

F Keep out area The area, expressed from nominal score line placement,that no features should be placed within.

D/2 + All registration

G Printed board thickness Overall printed board thickness to be scored. Per IPC standards

H Trueness/ Position The tolerance of two or more score lines on one side ofthe printed board. Measured from nominal, squarenessand actual position.

± 80 µm cumulative

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Routing is the process of profiling a pallet or printed boato the correct dimension using a cutting bit. This canperformed either by the use of a pin router and templatea CNC routing machine.

Frequently a combination of routing and scoring is uswhere both pallet and printed board are routed, leavinsmall connection bridge. This bridge is then scoredfacilitate removal following test and assembly.

The final method involves the use of routing and drillbreakaway tabs. Instead of scoring, a series of holesdrilled in the tab to facilitate removal. (See Figure 5-3.)

5.4 Dimensioning Systems Dimensioning systemsshallbe in accordance with the generic standard IPC-2221as follows:

5.4.1 Grid Systems When manually designing printeboards, grid systems are used to locate components, plthrough holes, conductor patterns, and other features oprinted board and its assembly so they need not be ividually dimensioned. When printed board featuresrequired to be off a grid, theyshall be individually dimen-sioned and toleranced on the master drawing.

IPC-2222-5-3

Figure 5-3 Breakaway tabs

Standard Tabs

Corner Below Flush Recess Below Flush

Mouse BiteBelow Flush

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Grid systems are always basic and have no tolerancetherefore all features located on a gridshall be tolerancedelsewhere on the master drawing. Grid systemsshall belocated with respect to a minimum of two printed boadatums.

The grid incrementshall be specified on the master draing. The choice of grid increment is based on the comnent terminal location for through-hole components, andthe component center for surface mount components.

Typical grid increments are multiples of 0.13 mm fthrough-hole components, and 0.05 mm for surface mcomponents.

5.4.2 Profiles, Cutouts and Notches It is recommendedthat the number of cutouts and notches on the printed bbe kept to a minimum in order to decrease the amountime and effort necessary to fabricate them. This ultimawill help to minimize end-product printed board cost.

All such cutouts and notches must not interfere withfabrication of other printed board/assembly features, sas the plating of edge-board contacts. The edges of intcutoutsshall be considered as external board edgesmeet all requirements for hole and conductors to eclearance (see 10.1.1). On multilayer printed boardslocation of lands, clearances, ground planes and otherductive pattern features must also be considered.

For printed board shape routing, it is recommended thacutouts and notches allow for a minimum of a 1.5 mradius on internal corners (assuming that a 3 mmdiameterrouter bit is used). Although a minimum internal radius0.75 mm can be obtained with a 1.5 mm diameter robit, this requirement should be avoided as router efficieand accuracy decreases substantially when smaller rbits are used. Recommended tolerances for the locationprofile of cutouts and notches are shown in Table 5-3; hever, the tolerances specified on the printed board drashall accommodate the dimensions and tolerances ofmating part.

Table 5-3 Tolerance of Profiles, Cutouts, Notches, and Keying Slots, as Machined, mm

Tolerances to be applied to profile of a surface: Level A 1 Level B Level C

Profile feature 0.25 0.20 0.15

Location where greatest basic location dimension is less than300.0

0.30 0.25 0.20

Location where greatest basic location dimension is greaterthan 300.0

0.35 0.30 0.25

1For definition of producibility level, see IPC-2221.

15

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6.0 ELECTRICAL PROPERTIES

Electrical propertiesshall be in accordance with thgeneric standard IPC-2221.

7.0 THERMAL MANAGEMENT

Thermal managementshall be in accordance with thgeneric standard IPC-2221.

8.0 COMPONENT AND ASSEMBLY ISSUES

Component assembly issuesshall be in accordance withthe generic standard IPC-2221 and as follows:

8.1 General Attachment Requirements In addition tothe general attachment requirements outlined in the genstandard IPC-2221, the followingshall apply:

8.1.1 Attachment of Wires/Leads to Terminals Forcases in which more than one wire is attached to a tenal, the largest diameter wire should be mounted tobottom-most post for ease of removal and repair. In geral, no more than three attachments should be madeach section of a turret or bifurcated terminal. As an exction, bus bar terminals may hold more than three wiresleads per section when specifically designed to hold m

8.1.2 Board Extractors Board extractors or handles aused to provide a convenient means of extractingprinted board from its mating connector. They are generused where the amount of force makes it difficult to safremove the board without damage to the electrical comnents or to the person removing the board.

Board extractors are commercially available and comevariety of shapes and sizes.

Extractors are usually of the camming type andmounted to the corners of the board. They providemechanical advantage for disengaging the connectors aconvenient place to grasp the board during removal.

Board extractors may be incorporated into the design ofboard, or may require separate conditions in the prinboard assembly. When board extractors are a part ofdesign, adequate reinforcementshall be used to properlyallow the extracting action to remove the board fromconnected assembly in the backplane (see Figure 8-1)

When board extractors are not a part of the printed boassembly, an extractor of the gripping variety may be u(see Figure 8-2). They grip the board in a particular awhich shall be kept free of components and circuitry. Ifhook-type board extractor is used, where a hook pathrough holes in the printed board, and then pulls the boout, special grommets should be used to reinforce thestructure to avoid board crazing or cracking.

16

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9.0 HOLE/INTERCONNECTIONS

9.1 General Requirements for Lands with Holes Gen-eral requirements for lands with holesshall be in accor-dance with the generic standard IPC-2221 and as follo

9.1.1 Land Requirements When eyelets or standoff terminals are used, the lands on external layersshall be sodesigned as to have a minimum a diameter of at leastmm greater than the maximum diameter of the projectof the eyelet of solder terminal flange.

9.1.2 Thermal Relief in Conductor Planes The relation-ship between the hole size, land and web area is critiTypically, divide 60% of the minimum land area diametby the number of webs desired to obtain the width of eaweb in accordance with the following example:

IPC-275-4-53

Figure 8-1 Permanent board extractor

IPC-275-4-54

Figure 8-2 External board extractor

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A. Land Size Calculation

Maximum hole size = 1.0 mm

Annular ring = 2 x 0.05 mm= 0.10 mm

Fabrication allowance = 0.25 mm

Minimum land size = 1.0 mm + 0.10 mm + 0.25 mm= 1.35 mm diameter

B. Thermal Relief Calculation

Total thermal width = 60% of land size= 0.6 x 1.35 mm= 0.80 mm

C. Original Web Size Calculation

2-web width = 1/2 of total thermal width= 0.50 x 0.80 mm= 0.40 mm



If the actual land diameter chosen is greater than the mmum value calculated, the percentage difference betwthe land diameters must be subtracted from the totalwidth calculation, i.e.:

Minimum land diameter = 1.35 mm

Actual land diameter = 1.70 mm

Percent difference = (1.70 - 1.35 mm)/1.35 mm= 25%

New total web width = total web widthpercent difference

= 0.80 mm - 25% (0.80 mm)= 0.60 mm

D. Adjusted Web Size Calculation

2-web width = 1/2 of new total web width= 0.50 x 0.60 mm= 0.30 mm



i-enb

Total cumulative copper web for all layers in any platethrough hole should not exceed 4.0 mm for 1 oz copper2.0 mm for 2 oz copper.

The total of the thermal relief cross-sectional area dividby the number of planes connected to the plated-throuhole shall not violate current carrying capacity requirements for a given hole.

If the individual web width violates the intended minimumconductor width itshall be specified on the master drawing.

9.1.3 Clearance Area in Planes Clearance area in planeshall be provided in accordance with Figure 9-1.

9.1.3.1 Small Pitch Clearance Area in Planes A specialprecaution must be observed when routing high speedcuits and/or very small pitch devices. When routing smpitch devices and/or vias routed on small grids, designmust remain aware of factors relating to power/grouplane clearance areas. When the pitch is very smdesigners must remain cognizant of the narrow foil wbetween clearance openings (see Figure 9-2). As the clance area (diameter) is made larger, the foil web betweclearance areas becomes smaller. Designs having vsmall foil webs are less desirable because of their reducurrent carrying capability, potential for increased voltadrop, higher EMI emissions, and reduced thermal dissiping characteristics. It is highly desirable for heat generatidevices to be ‘‘heatsinked’’ down through via holes andissipated across the surface of inner planes. For thesesons the foil web should be as large as possible and olapping clearance areas in planes should be avoided.the following formula when dealing with small pitchdevices and/or via holes, when routing on very small grid

IPC-2221-9-3

Figure 9-1 Clearance area in planes, mm

▼▼ ▼▼

▼

▼▼

▼

A + BA + B

0.25minimum

Nonfunctional LandPlated-throughHole

MaximumDrilledHole

▼▼▼▼

Unsupported Hole

▼

Shaded Area is CopperA = Electrical ClearanceB = Standard Manufacturing Allowance

▼ DielectricMaterial

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Typical example:Determine the desired width of foil web.Ex: 0.20 mm Web

Total available area = pitch - foil web= 1.25 - 0.20 mm= 1.05 mm

B = 0.25 mm min. fabrication allowance per Table 9-1 oIPC-2221.Clearance area (diameter) = hole diameter (max.) + 2B

= 0.35 mm + 2 (0.25 mm)= 0.35 mm + 0.50 mm= 0.85 mm

Note: Maximum clearance area (diameter) in the planecalculated by using the formula above and must not excethe total available area.

9.1.4 Nonfunctional Lands Nonfunctional lands shouldbe included on internal layers for all plated-through holeNonfunctional lands need not be used where electriclearance requirements do not permit, such as grouplanes, voltage planes and thermal planes. For high lacount boards, greater than 10 layers, it is recommendedremove some of the nonfunctional lands in the verticstack. Plated-through holes passing through internal cductive planes (ground, voltage, etc.) and thermal planshall meet the same minimum spacing requirementsconductors on internal layers, and should meet the mimum spacing requirements of Figure 9-2.

IPC-2222-9-4

Figure 9-2 Foil web size

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9.1.5 Conductive Pattern Feature Location ToleranceThe presentation in Table 9-1 is for the tolerance toapplied to the nominal dimension chosen for the locationthe lands connector contacts and conductors in relationthe datums. This tolerance includes tolerances for mapattern accuracy, material movement, layer registrationfixturing.

9.2 Holes Holesshall be in accordance with the generistandard IPC-2221 and as follows:

9.2.1 Unsupported Holes

9.2.1.1 Diameter of Unsupported Holes When using thebasic dimensioning system, holes shall be expressedterms of maximum material (MMC) and least material codiction (LMC) limits. The diameter of an unsupportecomponent holeshall be such that the MMC of the leadsubtracted from the MMC of the hole provides a clearanbetween a minimum of 0.15 mm and a maximum of 0mm. The number of different hole sizesshall be kept to aminimum. When flat ribbon leads are mounted throuunsupported holes, the difference between the nomdiagonal of the lead and the inside diameter of the unsported holeshall not exceed 0.5 mm andshall be not lessthan 0.15 mm.

9.2.1.2 Unsupported Hole Tolerance When using thebasic dimensioning system, holesshall be expressed interms of maximum material condition (MMC) and leamaterial condition (LMC) limits. The bilateral toleranceshown in Table 9-2 are used to determine the MMC-LMlimit for the appropriate hole diameter; thus, a hole 1.00.05 mm would be expressed as 0.95-1.05 mm.

9.2.1.3 Eyelet Hole Diameter When eyelets are usedthe diameter of holes in which eyelets are insertedshall notexceed the outside diameter of the barrel of the eyelet

Table 9-1 Feature Location Tolerances (Lands,Conductor Pattern, etc.) (Diameter True Position)

Greatest Board/X, Y Dimension Level A Level B Level C

Up to 300 mm 0.30 mm 0.20 mm 0.10 mm

Up to 450 mm 0.35 mm 0.25 mm 0.15 mm

Up to 600 mm 0.40 mm 0.30 mm 0.20 mmNote: Conductor pattern registration may be expressed in terms ofminimum annular ring violation, which establishes manufacturing registrationallowances.

Table 9-2 Minimum Unsupported Holes Tolerance Range(Difference between high and low hole size limits)

Hole Diameter Level A Level B Level C

0.1 - 0.8 mm 0.15 mm 0.10 mm 0.05 mm

0.81 - 1.6 mm 0.20 mm 0.15 mm 0.10 mm

1.61 - 5.0 mm 0.30 mm 0.20 mm 0.15 mm

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more than 0.15 mm. The relationships between maximand minimum barrel diameters and wire diametersshall beas shown in Table 9-3.

9.2.2 Plated-Through Holes The maximum and minimum plated-through hole diameters used to attach comnent leads or pins to the printed boardshall be evaluatedin accordance with Table 9-3. Both minimum and mamum leadsshall be taken into consideration in evaluatithe finished plated-through hole requirements. If the leaa ribbon lead, the minimum and maximum diagonal oflat ribbon leadshall be considered. Table 9-3 shows tlimits of the plated-through hole.

These limitsshall be optimized so that manufacturabilityenhanced to provide the most liberal tolerances allow(see Figure 9-3).

Unless otherwise specified, the hole sizeshall be the fin-ished plated size after solder coating or final platingfusing, if required. The hole sizeshall be specified on themaster drawing. Plated-through holes used for functiointerfacial connectionsshall not be used for the mountinof devices which put the plated-through hole in comprsion. Plated-through holes used for functional interfaconnectionsshall not be used for the mounting of eyelesolder terminals, or rivets. Plated-through holesshall beused for all interfacial connections on multilayer boaType 3 through Type 6 (inclusive). Platings and coatishall be in accordance with IPC-2221.

9.2.2.1 Aspect Ratio The aspect ratio of plated-througholes plays an important part in the ability of the manufturer to provide sufficient plating within the plated-throuhole, as well as in the reliability of the PTH/PTV structu

IPC-275-5-26

Figure 9-3 Lead-to-hole clearance

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(see IPC-D-279). Table 9-4 provides information on tproducibility of aspect ratios for various levels of compleity.

9.2.2.2 Plated-Through Hole Tolerances When usingthe basic dimensioning system, plated-through holes uto attach component leads or pins to the printed boshould be expressed in terms of MMC and LMC limiThe bilateral tolerances shown in Table 9-5 are useddetermine the MMC-LMC limit for the appropriate finished hole diameter. Thus, a hole 1.0 ± 0.05 mm wouldexpressed as 0.95-1.05 mm. When hole size is lessone-fourth the basic board thickness, the toleranceshall beincreased by 0.05 mm.

9.2.2.3 Minimum Hole Sizes for Plated-Through HoleVias In order to meet the performance requirements ofvarious classes of equipments, the plated-through holeto board thickness aspect ratio for plated-through holeshould be in accordance with Table 9-4. Table 9-6 proviinformation on the minimum drilled hole to be usedconjunction with various board thicknesses. The tareflects the three classes of equipment assuming thatclass requires a slightly more severe environment, thaving to meet more stringent thermal cycling conditio(see IPC-D-279).

If a particular class requires more stringent cycling thshown in the table, the user may invoke the requiremeof a larger drilled hole size.

Solder may fill the through hole or via if processed wfused tin-lead plate or solder coating. Partial fillingassembly can create stress concentrations affecting reliity. For drilled hole diameters 0.35 mm or less and aspratios of 4:1 or larger, the fabricator should mask or pby a suitable method the plated through vias to preventry of solder.

The drilled hole size used for through hole viasshall berepresented on the master drawing as the maximum plathrough hole dimension that assumes that the hole cona minimum plating thickness. No minimum plated-throuhole dimension should be specified since the through-hvia contains no component lead or pin and could theorcally be plated shut. Thus, a master drawing call out0.0-0.2 mm diameter reflects drilling a 0.25 mm hole thcan contain a minimum plating of 0.025 mm to a maximuplating of 0.125 mm copper per side.

In addition, Table 9-6 contains a letter code in each ofboxes. This letter code reflects the producibility levelcomplexity in each of the particular hole size to aspratios.

9.2.3 Etchback Etchback, when required, will reducthe annular ring support on internal layers of the boaTherefore, this should be taken into account when specing plated-through hole land size. However, the maxim

19


Table 9-3 Plated-Through Hole Diameter to Lead Diameter Relationships

Lead Diameter Level A Level B Level C

Maximum hole tominimum leaddiameter

No greater than 0.7 mm overminimum lead diameter



Minimum hole tomaximum leaddiameter

No less than 0.25 mm overmaximum lead diameter

No less than 0.20 mm overmaximum diameter

No less than 0.15 mm overmaximum lead diameter

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etchback allowed on the master drawingshall not begreater than the minimum design annular ring.

9.3 Drill Size Recommendations for Printed BoardsDrill sizes as related to maximum board thicknessshown in Table 9-7. These drills may be used to dunsupported or plated-through holes in rigid printboards.

Although the designer rarely specifies the drilled hole sthese dimensions may be used in determining minimannular ring calculations, or minimum land sizes.

Also shown in Table 9-7 are the maximum board thicnesses to which the various drill sizes should be appl(Note: These dimensions are maximums. Thinner boamay be used to accommodate all drills shown within a dset category.) Designers are encouraged to limit the nber of drill selections to approximately 10 drill sizes peach printed board. Where possible a lesser number shbe used, recognizing that the manufacturer needs cedrill sizes for tooling hole and other configurations. Itrecommended that the designer select no more thandrill size from any given row in order to optimize drill sizoperation. The information in Table 9-7 is a suggesguideline based on the availability of existing manufacting drills.

Table 9-4 Plated-Through Hole Aspect Ratio

Level A Level B Level C

Aspect Ratios ≤5:1 6:1 to 8:1 9:1 and up

20

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10.0 GENERAL CIRCUIT FEATURE REQUIREMENTS

10.1 Conductor Characteristics Conductor characteristics shall be in accordance with the generic standard IP2221 and as follows:

10.1.1 Edge Spacing Except for edge-board contactthe minimum distance between conductive surfaces andedge of the finished board, or a non-plated through hshall not be less than the minimum spacing specifiedTable 6-1 of IPC-2221 plus 0.4 mm. Printed boards tslide into guidesshall have a minimum external conductoto guide distance of 1.25 mm or minimum electrical cleance (see Table 6-1 of IPC-2221), whichever is greaSpecial design applications in areas such as high voltasurface mount, and radio frequency (RF) technology mrequire variances to these requirements. Ground andsink planes may extend to the edge when requireddesign.

Table 9-7 Drill Size Recommendations Related toMaximum Board Thickness

Drill size (mm)Maximum Board Thickness

(mm), as drilled

≤0.10 ≤0.25

0.15-0.25 ≤1.0

0.30-0.45 ≤1.6

0.50-0.85 ≤3.2

0.90-1.05 ≤4.8

≤1.10 ≤6.4

Table 9-5 Minimum Plated-Through Hole Diameter Tolerance Range, mm(Difference between high and low hole size limits)

Hole Diameter Level A Level B Level C

0.1 to 0.8 0.20 0.15 0.10

>0.8 to 1.6 0.30 0.20 0.10

>1.6 to 5.0 0.40 0.30 0.20

Table 9-6 Minimum Drilled Hole Size for Plated-Through Hole Vias

Board Thickness Class 1 Class 2 Class 3

<1.0 mm Level C 0.15 mm Level C 0.2 mm Level C 0.25 mm

1.0 mm to 1.6 mm Level C 0.2 mm Level C 0.25 mm Level B 0.3 mm

1.6 mm to 2.0 mm Level C 0.3 mm Level B 0.4 mm Level B 0.5 mm

>2.0 mm Level B 0.4 mm Level A 0.5 mm Level A 0.6 mmNote: If copper plating thickness in hole is greater than 0.03 mm, hole size can be reduced by one class.

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10.1.2 Balanced Conductors Whenever possible, toreduce bow and twist and to increase dimensional stabiconductors should be balanced within an individual layConductor routing density should be spread throughoutboard wherever possible, to avoid the need for special eing or plating thieves.

Plating thieves are added metallic areas which are nonfutional within the finished board profile but allow uniformplating density, giving uniform plating thickness over thboard surface.

The multilayer printed board structure should also bebalanced as possible providing equal layers of signal cductors and planes to either side of the center of the mtilayer construction.

10.1.3 Flush Conductors for Rotating or Sliding Con-tacts When flush circuits are required for application amating contact surfaces, the degree of flushnessshall meetthe requirements of Table 10-1. Figure 10-1 (A andshows a typical flush circuit design.

Note:The level of flushness required is normally a functioof factors related to the mating contact, such as contsize, shape, load, rotational force, surface friction, etc. Irecommended that the designer fully understanddynamics of the mating contact system before establishsurface flushness requirements.

Table 10-1 Surface Flushness Requirements

Level A Level B Level C

As agreed between userand supplier

± 0.013 mm ± 0.005 mm

IPC-275-5-13a

Figure 10-1A Typical flush circuit

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10.1.4 Metallic Finishes for Flush Conductors Metallicfinishes for flush conductor contacts should be gold onickel, or other suitable corrosion resistant, low contaresistance finish.

10.2 Land Characteristics Land characteristicsshall bein accordance with the generic standard IPC-2221 andfollows:

10.2.1 Lands for Interfacial Connection Vias Lands forinterfacial connectionsshall meet the requirements of 10.1

10.2.2 Offset Lands Lands, when used in conjunctionwith clinched leads, may be located adjacent to (not srounding) the lead termination hole. The landshall be asufficient distance from the hole to allow clipping of thpart lead prior to unsoldering the part lead from the lan

10.2.3 Conductive Pattern Feature Location Toler-ance The presentation in Table 9-1 is for the tolerancebe applied to the nominal dimension chosen for the lotion of the lands connector contacts and conductors in retion to the datums. This tolerance includes tolerancesmaster pattern accuracy, material movement, layer registion and fixturing. (See IPC-SM-782.)

10.2.4 Nonfunctional Lands See 9.1.4.

10.3 Large Conductive Areas Large conductive areas(Planes 3 mm wide or larger conductors) increase the lilihood for blistering, warping, or heat shielding durinwave or reflow soldering.

Large areas that cover more than a 25.0 mm diameter mbe broken up into a cross-hatched or similarly patternarea (see Figure 10-2). Modifications to large conductareas shall not adversely impact the electrical charactetics or performance of the board. Large conductive areshould not be on the solder side of the board unless soresist or similar is used.

External conductors that extend beyond a 25.0 mm diaeter circle should contain etched areas that break uplarge conductive area, but retain the continuity and funtionality of the conductor. If etched areas are not provideother methods should be used to minimize blisteringbowing.

Large conductive areas should, if possible, be on themary side of the board. If solder resist is employed ovmeltable metals, conductive areas wider than 1.3 mmshallnot be employed under the solder resist coatings.

When a conductive area that extends beyond a 25.0diameter is used on a internal layer, the conductive a

21


IPC-275-5-13b

Figure 10-1B Surface flushness conditions

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should be placed as near to the center or the board assible, and should contain etched areas that will break uplarge conductive area, but will retain the continuity anfunctionality of the conductor. When UL requirements aimposed, the areashall be within the limits approved byUL for the printed board manufacturer.

IPC-275-5-12

Figure 10-2 Cross-hatched large conductive layers withisothermal conductors

22

11.0 DOCUMENTATION

Documentationshall be in accordance with the generistandard IPC-2221 and as follows:

11.1 Filled Holes Via holes designated to be filled by thdesign requirementsshall be identified on the drawing.

11.2 Nonfunctional Holes Electrically nonfunctionalsupported holes should be identified as such on the fabrtion or assembly drawing and do not need to meet the etrical connection requirement.

12.0 QUALITY ASSURANCE

Quality Assuranceshall be in accordance with the generistandard IPC-2221.


INDEX

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1

.4

The following is an index of key subjects related to scific paragraph numbers in this standard. The index is onized alphabetically.

A

Aspect Ratio 9.2.2.1Assembly and Test 5.3.1Assembly Requirements 5.3Assembly Types 1.6Attachment Requirements 8.1

B

Balanced Conductors 10.1.2Board Extractors 8.1.2Board Geometries 5.2.1Board Type 1.5.1Borders and Spacing 5.2.1.1Bow and Twist Designation 4.3.7.6

C

Circuit Feature Requirements 10.0Classification of Products 1.5Clearance Area in Planes 9.1.3Component and Assembly Issues 8.0Conductive Materials 4.4Conductive Pattern Feature Location

Tolerance 9.1.5, 10.2.3Conductor Characteristics 10.1Copper Foil Designation 4.3.7.3

D

Diameter of Unsupported Holes 9.2.1.1Dielectric Base Materials 4.2Dielectric Thickness 4.3.7.2Dielectric Thickness Measurement 4.3.1Dielectric Thickness/Spacing 4.3.2Dimensional Aspect Ratio 5.2.1.2Dimensioning Systems 5.4Documentation 11.0Double-Clad Laminates 4.3.6Drill Size Recommendations 9.3

E

Edge Spacing 10.1.1Electrical Properties 6.0Electrical Requirements 4.3.4.4Epoxy 4.3.4.1Epoxy Laminates 4.2.1Etchback 9.2.3Eyelet Hole Diameter 9.2.1.3

-F

Fabrication Requirements 5.1Filled Holes 11.1Flush Conductors 10.1.3

GGeneral Requirements 3.0Glass Style 4.3.4.3Grid Systems 5.4.1

HHigh-Temperature Laminates 4.2.2High-Temperature Prepregs 4.3.4.2Hole/Interconnections 9.0Holes 9.2

LLaminate 4.2.4Laminate Materials 4.3Laminate Properties 4.3.3Land Characteristics 10.2Land Requirements 9.1.1Lands for Interfacial Connection Vias 10.2.Lands with Holes 9.1Large Conductive Areas 10.3

MMarkings and Legends 4.6Material Selection 4.1Materials 4.0Mechanical Support 5.2.2Mechanical/Physical Properties 5.0Metallic Finishes for Flush Conductors 10.1Minimum Hole Sizes for PTH Vias 9.2.2.3

NNonfunctional Holes 11.2Nonfunctional Lands 9.1.4, 10.2.4

OOffset Lands 10.2.2Organic Protective Coatings 4.5

PPit Designation 4.3.7.4Plated-Through Hole Tolerances 9.2.2.2Plated-Through Holes 9.2.2Prepreg 4.3.4Product/Board Configuration 5.2Profiles, Cutouts and Notches 5.4.2

QQuality Assurance 12.0

23

5


RResin Content 4.3.3.2

SSingle-Clad Laminates 4.3.5Small Pitch Clearance Area in Planes 9.1.3.1Special Clad Materials 4.2.3

TThermal Management 7.0Thermal Relief in Conductor Planes 9.1.2Thickness Class Tolerance Designation 4.3.7.Thickness Tolerance 4.3.3.1Typical Material Designation 4.3.7.1

UUnsupported Hole Tolerance 9.2.1.2Unsupported Holes 9.2.1

WWires/Leads Attachment to Terminals 8.1.1

24

ANSI/IPC-T-50 Terms and Definitions forInterconnecting and Packaging Electronic CircuitsDefinition Submission/Approval Sheet

The purpose of this form is to keepcurrent with terms routinely used inthe industry and their definitions.Individuals or companies areinvited to comment. Pleasecomplete this form and return to:

IPC2215 Sanders RoadNorthbrook, IL 60062-6135Fax: 847 509.9798

SUBMITTOR INFORMATION:

Name:

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City:

State/Zip:

Telephone:

Date:

❑ This is a NEW term and definition being submitted.❑ This is an ADDITION to an existing term and definition(s).❑ This is a CHANGE to an existing definition.

Term Definition

If space not adequate, use reverse side or attach additional sheet(s).

Artwork: ❑ Not Applicable ❑ Required ❑ To be supplied

❑ Included: Electronic File Name:

Document(s) to which this term applies:

Committees affected by this term:

Office UseIPC Office Committee 2-30

Date Received:Comments Collated:Returned for Action:Revision Inclusion:

Date of Initial Review:Comment Resolution:Committee Action: ❑ Accepted ❑ Rejected

❑ Accept Modify

IEC ClassificationClassification Code • Serial Number

Terms and Definition Committee Final Approval Authorization:Committee 2-30 has approved the above term for release in the next revision.

Name: Committee: Date:IPC 2-30


IPC World Wide Web Page www.ipc.orgOur home page provides access to information about upcoming events, publications and videos, membership,and industry activities and services. Visit soon and often.

Education and TrainingIPC conducts local educational workshops and national conferences to help you better understand emergingtechnologies. National conferences have covered Ball Grid Array and Flip Chip/Chip Scale Packaging. Someworkshop topics include:

Printed Wiring Board Fundamentals High Speed DesignTroubleshooting the PWB Manufacturing Process Design for ManufacturabilityChoosing the Right Base Material Laminate Design for AssemblyAcceptability of Printed Boards Designers Certification PreparationNew Design Standards

IPC video tapes and CD-ROMs can increase your industry know-how and on the job effectiveness.

For more information on programs, contact John Rileytel 847/790-5308 fax 847/509-9798e-mail: [email protected] www.ipc.org

For more information on IPC Video/CD Training, contact Mark Pritchardtel 505/758-7937 ext. 202 fax 505/758-7938e-mail: [email protected] www.ipc.org

Training and CertificationIPC-A-610 Training and Certification Program“The Acceptability of Electronic Assemblies” (ANSI/IPC-A-610) is the most widely used specification for thePWB assembly industry. An industry consensus Training and Certification program based on the IPC-A-610 isavailable to your company.

For more information, contact John Rileytel 847/790-5308 fax 847/509-9798e-mail: [email protected] www.ipc.org/html/610.htm

IPC Printed Circuits ExpoIPC Printed Circuits Expo is the largest trade exhibition in North America devoted to the PWB industry. Over 90technical presentations make up this superior technical conference.

For exhibitor information, For registration information:Contact: Ken Romeo tel 847/790-5361 fax 847/509-9798tel 630-434-7779 e-mail: [email protected] www.ipc.org

How to Get InvolvedThe first step is to join IPC. An application for membership can be found on page 74. Once you become amember, the opportunities to enhance your competitiveness are vast. Join a technical committee and learn fromour industry’s best while you help develop the standards for our industry. Participate in market researchprograms which forecast the future of our industry. Participate in Capitol Hill Day and lobby your Congressmenand Senators for better industry support. Pick from a wide variety of educational opportunities: workshops,tutorials, and conferences. More up-to-date details on IPC opportunities canbe found on our web page: www.ipc.org

For information on how to get involved, contact:Jeanette Ferdman, Membership Managertel 847/790-5309 fax 847/509-9798e-mail: [email protected] www.ipc.org

BE

NE

FIT

S O

F I

PC

ME

MB

ER

SH

IP

March 16-18, 1999Long Beach, California

April 4-6, 2000San Diego, California

for SiteMembershipApplication

Our facility purchases, uses and/or manufactures printed wiring boards or other electronic interconnectionproducts for our own use in a final product. Also known as original equipment manufacturers (OEM).

We are representatives of a government agency, university, college, technical institute who are directlyconcerned with design, research, and utilization of electronic interconnection devices. (Must be a non-profit or not-for-profit organization.)

■■ One-sided and two-sided rigidprinted boards

■■ Multilayer printed boards

■■ Flexible printed boards■■ Flat cable■■ Hybrid circuits

■■ Discrete wiring devices■■ Other interconnections

IS YOUR INTEREST IN:

■■ purchasing/manufacture of printed circuit boards

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What is your company’s main product line?

_________________________________________________________________________________

WHAT PRODUCTS DO YOU

MAKE FOR SALE?

■■ Turnkey■■ SMT■■ Chip Scale Technology

■■ Through-hole■■ Mixed Technology

■■ Consignment■■ BGA

Our facility assembles printed wiring boards on a contract basis and/or offers other electronic interconnection products for sale.

Our facility supplies raw materials, machinery, equipment or services used in the manufacture orassembly of electronic interconnection products.

Thank you for your decision to join IPC. IPC Membership is site specific, whichmeans that IPC member benefits are available to all individuals employed at the site designated on the other side of this application.

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Please be sure to complete both pages of application.

PLEASE CHECK

APPROPRIATE

CATEGORY

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INDEPENDENTPRINTEDBOARDMANUFACTURERS

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INDEPENDENTPRINTED BOARDASSEMBLERSEMSI COMPANIES

■

OEM –MANUFACTURERS

OF ANY END

PRODUCT USING

PCB/PCAS

OR CAPTIVE

MANUFACTURERS

OF PCBS/PCAS

■

INDUSTRY

SUPPLIERS

■

GOVERNMENT

AGENCIES/ACADEMIC

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LIAISONS


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Standard Improvement Form IPC-2222The purpose of this form is to provide theTechnical Committee of IPC with inputfrom the industry regarding usage ofthe subject standard.

Individuals or companies are invited tosubmit comments to IPC. All commentswill be collected and dispersed to theappropriate committee(s).

If you can provide input, please completethis form and return to:

IPC2215 Sanders RoadNorthbrook, IL 60062-6135Fax 847 509.9798

1. I recommend changes to the following:

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sectional design standard for rigid organic printed...

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