seminar on packaging suruchi

8/2/2019 Seminar on Packaging Suruchi

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PACKAGING


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What is Electronic

Packaging? Packaging provides the interconnection

Chip Protection

Environmental, thermal, mechanical

CommunicationMaximize I/O

Power

Heat removal


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WHAT IS PACKAGING?

Packaging refers to The packaging of the interconnected chips

The interconnection for signal transmission,power & ground

The encapsulation for protecting the chips

The heat sinks or the other cooling devices

The housing for electromagnetic interferenceshielding


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Goals of Electronic

PackagingMaximize I/O

Minimize thermal issues

Heat dissipation Thermal stress

Environmental protection and encapsulation

Lowest cost needed to get results

Drive to continuously reduce size and power

Talk by DL Thomas of Endicott


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Performance

Cycle Time

Circuit Delay

Circuit Technology

Chip Power cooling (W/cm2) Package Delay

Circuit Density

I/O (Connections/cm2

) Wireability (Lines/cm)

Interconnection length

Propagation medium(Circuits/ns)


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LEVELS OF PACKAGING

Level 0:bare chip as removed from the finishedsurface

Level 1:bare chip mounted on a chip carrier &

encapsulated as a packaged chip Level 2:printed circuit board with packaged

chips, modules & other components Level 3:motherboard into which PCB are inserted.

Level 4:electronic module Level 5:system formed by electronic module


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Design Considerations

Hazards to be protected against: mechanicaldamage, exposure to weather and dirt,electromagnetic interference, etc.

Heat dissipation requirements

Tradeoffs between tooling capital cost and per-unit cost

Tradeoffs between time to first delivery andproduction rate

Availability and capability of suppliers


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Design Considerations

(contd)User interface design and convenience

Ease of access to internal parts when required

for maintenance

Product safety, and compliance with regulatorystandards

Esthetics, and other marketing considerationsService life and reliability


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Different variations in

Packaging Conventional Variation: one or more chips areattached to ceramic substrate via soldered joints

Direct Chip Attach Module: The chip is attacheddirectly on the card, called DCAM

Multichip Module Laminate: The chip is attached

via a cardlet,one of many small cards attached toa larger card, resulting in MCML


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Materials andProcessing

Materials properties

Good insulating characters

Low dielectric constant

High thermal conductivity

High strength and toughness

Stability at the processing

temperatures Thermal expansion near attachments

Acceptable cost


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Electronic Connections

Developed in the

1960s

Leads perpendicularto the body of thepackage

DIP = dual-inline-package


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Electronic

Connections(contd)Surface Mount Technology (SMT)

Method for constructingelectronic circuits;components are mounteddirectly onto the surfaceof printed circuit boards

Usually smaller than its

leaded counterpart(because it has no leads orsmaller leads).


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(contd)Pin Grid Array (PGA)Integrated circuit is mounted ona ceramic slab

Pins can then be inserted intothe holes in a printed circuit boardand soldered in place.

This type of package occupiesless space than older types such asthe dual in-line package (DIL or

DIP).


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(contd)

Ceramic or plastic chip

carrierLeads project downand away all four sidesof a square package

Quad Flat Package (QFP)


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Electronic Connection

Flip Chip- PGA

Allows the

microprocessor tooperate more easily atits optimal temperaturesby designing theprocessor core on the

"flip side" (or backside)of the chip, facing away

from the motherboard


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ElectronicConnections(contd)

Ball Grid Array- BGA

Solution to theproblem of producinga miniature packagefor an integratedcircuit with many

hundreds of pins.


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Electronic Connections(contd)

Land Grid Array- LGA

Used by Intel to moreevenly distribute power

Less expensive than

PGA and BGA


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INTERCONNECTIONS

What are interconnections?

It constitute the communications bottleneck ofelectronic digital system.


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Types ofinterconnections

Electrical: These include Electrical conductorsWires

Cables Connectors

Optical

Fibers


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Uses ofinterconnections

Creating monopoly

Introducing competition

Protecting competition


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What is Connector ?

An electromechanical system that provides aseparable interface b/w 2 electronic subsystemswithout an unacceptable effect on signal integrity

or loss in power


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Connector Types

Three major connector types

Board to Board

Wire to Board

Wire to Wire


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Connector Applications

Signal Application: It span the range of currentfrom microamps to hundred of milliamps.Drivingvoltages for this are generally a few volts.

Power Application:It faces the additionalrequirement of thermal management.


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Consideration forconnectors

Two types of consideration

Electrical Considerations

Mechanical considerations


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ElectricalConsiderations

Electrical consideration in connector selectioninclude:

Contact current ratings

Contact resistance Contact impedance;capacitance &inductance Power ratingShielding and filtering requirements


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Mechanical Considerations

Number of contacts Insertion/extraction forceNumber of expected connect/disconnect cycles

Body style and profile Polarization and keying requirementShock and vibrationArea and height of connectorManual or automatic connector placement


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Connector Problems

Signal Degradation: it is due to the faster clockrates and shorter rise time

Cross Talk:it is caused by inductive andcapacitive coupling b/w contacts

There are mainly 2 types of crosstalk


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Connector

Problems(contd) Backward (Near-end): it is measured at the

driving end of the connector & represents thesum of capacitive and inductive coupling.

Forward (Far-end): is measured at the receivingend of the connector & represents capacitiveminus inductive coupling.


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What are wires &cables ?

Selection of wires for interconnection involvesseveral consideration

Color coding

Temperature rating

Solid or stranded

Individual,multi cable, flat cable

Current carrying capacity


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Wires & Cable(contd)

Temperature rating of wires depends on

Test environment Assembly environment

Use environment


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Prevention of vibration

The circuit elements should be mounteddirectly to a mechanically stiff substrate ofprinted wiring board.

Employ sufficient hold down techniques tocircuit assemblies & devices by staking throughthe use of adhesive interfaces and screws toreduce relative motion b/w components & theirmounting surfaces.

Leads should be soldered into position with verylittle prestressing. Signal wires RF cables should be clamped

approx. 1-in intervals to prevent fraying duringvibration


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Prevention ofvibration(contd)

Sensitive circuits should be packaged in a housingmade from high-density materials such as steel

or tungsten.


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What is Reliability and Testing in engineering?

Packaging is backbone of electronics

Employs almost every engineering discipline

Easily affected by environmental factors

Evaluate lifetimes of years in weeks

Reliability and Testing


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Testing and Modeling

Air flow

Temperatures

Deformation

Stresses and solderfatigue



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Accelerate Failure Mechanisms

- Temperature/humidity/voltage corrosion& migration

- Thermal Accelerated oxidation,undesirable chemical processes

- Mechanical Joint strength, shipping,cracks, de-lamination,



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Future Trends inElectronic Packaging

Higher I/O, increased density

Reduced voltage (noise sensitivity)

Increased energy dissipation requirements

Multiple voltage levels

Higher operating frequency (RF range)

Environmental constraints (Pb elimination)


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THANK YOU

seminar on packaging suruchi

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