advanced rigid-flex circuit constructions
TRANSCRIPT
Manufacturing That Eliminates Risk & Improves Reliability
Advanced Rigid-Flex
Circuit Constructions
06.29.17
Manufacturing That Eliminates Risk & Improves Reliability
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Introduction
Todays Rigid-Flex materials and construction methods allow for a wide variety of advanced design configurations.
These options create the opportunity to achieve higher levels of design integration and packing density.
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Introduction
Options Include:
– Higher Flex Layer Counts
– Blind & Buried Via Structures
– ZIF Connections
– Flex Area Components
– Asymmetrical Constructions
– Shielded Flex Areas
– Multiple Rigid Area Thicknesses
In this webinar we will introduce and discuss the benefits and applications of some of the more common advanced rigid-flex circuit board constructions.
Many additional configurations and combinations are available.
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Agenda
Standard Construction Review
Advanced Rigid-Flex Construction Options:
– Odd Number Layer Counts
– Asymmetrical Constructions
– Varying Flex Layer Count Areas
– Integrated ZIF Connections
– Blind & Buried Vias
– Air Gap Flex Layer Constructions
– Multiple Rigid Area Thicknesses
– Shielded Flex Layers
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Standard Rigid-Flex Construction
Symmetrical construction
Even layer counts in both rigid & flex areas
Impedance Control available
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Standard Rigid-Flex Construction
Most common construction (approx. 60%)
Soldmask (LPI)
Layer 1 Base Copper um + Plated 20 um min.
FR-4 (170 tg min.)
Layer 2 Copper
Coverlay:
Coverlay Adhesive:
Layer 3 Copper
Polyimide Core (Adhesiveless) Flex Thickness Rigid
Layer 4 Copper Thickness
Coverlay Adhesive:
Coverlay:
Layer 5 Copper
FR-4 (170 tg min.)
Layer 6 Base Copper um + Plated 20 um min.
Soldmask (LPI)
Prepreg (2 x 1080, no flow)
Prepreg (2 x 1080, no flow)
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Odd Layer Count Constructions
7 layer Rigid area with 3 Flex layers
Soldmask (LPI)
Layer 1 Base Copper um + Plated 20 um min.
FR-4 (170 tg min.)
Layer 2 Copper
Coverlay:
Coverlay Adhesive:
Layer 3 Copper
Polyimide Core (Adhesiveless)
Adhesive Rigid
Layer 4 Copper Thickness
Polyimide Flex Thickness
Layer 5 Copper
Coverlay Adhesive:
Coverlay: 25 um
Layer 6 Copper
FR-4 (170 tg min.)
Layer 7 Base Copper um + Plated 20 um min.
Soldmask (LPI)
Prepreg (2 x 1080, no flow)
Prepreg (2 x 1080, no flow)
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Odd Layer Count Constructions
5 layer Rigid area with 1 Flex layer
Soldmask (LPI)
Layer 1 Base Copper um + Plated 20 um min.
FR-4 (170 tg min.)
Layer 2 Copper
Coverlay:
Coverlay Adhesive:
Layer 3 Copper Flex Thickness Rigid
Polyimide Core (Adhesiveless) Thickness
Layer 4 Copper
FR-4 (170 tg min.)
Layer 5 Base Copper um + Plated 20 um min.
Soldmask (LPI)
Prepreg (2 x 1080, no flow)
Prepreg (2 x 1080, no flow)
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Odd Layer Count Constructions
3 layer Flex area configuration allows for two sided shielding requirements in flex areas.
– Stripline Impedance Control
– RF & EMI Requirements
Odd layer counts can apply to both flex & rigid areas independent of each other.
Minimizes flex area thickness for improved flexibility and mechanical bend capability / reliability.
IPC 2223C compliant.
Reduces cost by minimizing total number of flex layers required.
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Asymmetrical Constructions
Applications:
– Convoluted impedance requirements
– Blind via constructions
• Minimizes blind via aspect ratio for improved manufacturability reliability.
May result in warp & twist in assembly arraywhich may require a hold down fixturefor transport through assembly.
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Asymmetrical Constructions
Soldmask (LPI)
Layer 1 Base Copper 18 um + Plated 35 um min.
FR-4 (170 tg min.)
Layer 2 Copper
Prepreg (1 x 1080, no flow)
Layer 3 Copper
FR-4 (170 tg min.)
Layer 4 Copper Rigid
Coverlay: Thickness
Coverlay Adhesive:
Layer 5 Copper
Polyimide Core (Adhesiveless) Flex Thickness
Layer 6 Copper
Coverlay Adhesive:
Coverlay:
Layer 7 Copper
FR-4 (170 tg min.)
Layer 8 Base Copper 18 um + Plated 35 um min.
Prepreg (2 x 1080, no flow)
Prepreg (1 x 1080, no flow)
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Varying Flex Layer Count Constructions
Allows for tighter bend capabilities in reduced flex layer count area.
Multiple configurations available.
Requires use of “Air Gap” flex layer construction.
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Varying Flex Layer Count Constructions
Soldmask
Layer 1 Base Copper um + Plated 20 um min.
FR-4 (170 tg min.)
Coverlay:
Coverlay Adhesive:
Layer 2 Copper
Polyimide Core (Adhesiveless) Flex
Layer 3 Copper Thickness
Coverlay Adhesive:
Coverlay: Rigid
Thickness
Coverlay:
Coverlay Adhesive:
Layer 4 Copper
Polyimide Core (Adhesiveless) Flex
Layer 5 Copper Thickness
Coverlay Adhesive:
Coverlay:
FR-4 (170 tg min.)
Layer 6 Base Copper um + Plated 20 um min.
Soldmask
AIR GAP
Prepreg (2 x 1080, no flow)
Prepreg (3 x 1080, no flow)
Prepreg (2 x 1080, no flow)
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Integrated ZIF Tail Constructions
Eliminates the need for a ZIF connector and separate flex circuit.
Reduces real-estate requirements in rigid area(s).
Improves reliability through elimination of points of interconnect.
– ZIF connector solder joints, ZIF finger contacts
Available in a wide variety of configurations.
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Integrated ZIF Tail Constructions
Soldmask (LPI)
Layer 1 Base Copper 35 um + Plated 20 um min.
ZIF
Adhesive Thickness
Polyimide Core (Adhesiveless) Rigid Thickness Flex Thickness
Layer 2 Copper
Coverlay Adhesive:
Coverlay:
Layer 3 Base Copper 35 um + Plated 20 um min.
Soldmask (LPI)
Prepreg (2 x 1080, no flow)
Prepreg (2 x 1080, no flow)
FR-4 (170 tg min.)
Polyimde Stiffener
FR-4 (170 tg min.)
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Blind & Buried Constructions
Applications: Similar to Rigid PCB Blind & Buried Constructions
– High density BGA applications with via in pad etc.
May require an asymmetrical construction if blind vias interconnect to flex layers.
Configurations may be limited due to number of sequential lamination cycles required. Less than Rigid PCBs due to material dimensional tolerances and manufacturing methods.
Via fill and cap available.
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Blind & Buried Constructions
Soldmask (LPI)
Layer 1 Base Copper 18 um + Plated 35 um min.
FR-4 (170 tg min.)
Layer 2 Copper
Prepreg (1 x 1080, no flow)
Layer 3 Copper
FR-4 (170 tg min.)
Layer 4 Copper
Coverlay:
Coverlay Adhesive:
Layer 5 Copper
Polyimide Core (Adhesiveless) Flex Thickness Rigid
Layer 6 Copper Thickness
Coverlay Adhesive:
Coverlay:
Layer 7 Copper
FR-4 (170 tg min.)
Layer 8 Base Copper 18 um + Plated 35 um min.
Prepreg (2 x 1080, no flow)
Prepreg (1 x 1080, no flow)
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Flex Layer Air Gap Constructions
Flex layers configured as independent pairs of 2.
Allows design to meet IPC 2223C design guidelines.
– Construction results in no flex adhesives in rigid areas.
– Preferred configuration for 4 or more flex layers.
Provides greater flexibility due to flex layers bendingindependent of each other.
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Flex Layer Air Gap ConstructionsSoldmask
Layer 1 Base Copper um + Plated 20 um min.
FR-4 (170 tg min.)
Coverlay:
Coverlay Adhesive:
Layer 2 Copper
Polyimide Core (Adhesiveless)
Layer 3 Copper
Coverlay Adhesive:
Coverlay:
Coverlay:
Coverlay Adhesive:
Layer 4 Copper Rigid
Polyimide Core (Adhesiveless) Flex Thickness Thickness
Layer 5 Copper
Coverlay Adhesive:
Coverlay:
Coverlay:
Coverlay Adhesive:
Layer 6 Copper
Polyimide Core (Adhesiveless)
Layer 7 Copper
Coverlay Adhesive:
Coverlay:
FR-4 (170 tg min.)
Layer 8 Base Copper um + Plated 20 um min.
Prepreg (3 x 1080, no flow) AIR GAP
AIR GAP
Prepreg (2 x 1080, no flow)
Prepreg (3 x 1080, no flow)
Prepreg (2 x 1080, no flow)
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Multiple Rigid Area Thickness Construction
Rigid area thickness vary between sections.
Practically limited to 2 rigid thicknesses maximum.
May have limits in rigid area thicknesses due to required materials.
Very costly construction
– Manufacturing process is equivalent to making 2 boards to get 1.
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Multiple Rigid Area Thickness Construction
Soldmask (LPI)
Layer 1 Base Copper 18 um + Plated 30 um min.
Soldmask (LPI)
Layer 2 Copper + Plating
Coverlay:
Coverlay Adhesive:
Layer 3 Copper
Polyimide Core (Adhesiveless) Rigid Thickness 1 Rigid
Layer 4 Copper Thickness 2
Coverlay Adhesive:
Coverlay:
Layer 5 Copper + Plating
Soldmask (LPI)
Layer 6 Base Copper 18 um + Plated 30 um min.
Prepreg
Prepreg
FR-4 (170 tg min.)
FR-4 (170 tg min.)
Prepreg (1 x 106, + 1 x 1080, no flow)
Prepreg (1 x 106, + 1 x 1080, no flow)
Prepreg (2 x 1060, no flow)
Prepreg (2 x 1060, no flow)
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Shielded Flex Layers Construction
Allows for effective EMI & RF shielding without additional copper layers.
– Reduced cost
– Thinner flex area construction for improved flexibility
Uses specialized shielding films (i.e.: Tatsuta, APlus etc.)
Shielding films are laminated to Flex areaCoverlays and interconnect to groundthrough selective Coverlay openings andelectrically conductive adhesive.
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Shielded Flex Layers Construction
Soldmask (LPI)
Layer 1 Base Copper um + Plated 25 um min.
Shield Layer
Coverlay:
Coverlay Adhesive:
Layer 2 Copper
Polyimide Core (Adhesiveless) Flex Thickness Rigid
Layer 3 Copper Thickness
Coverlay Adhesive:
Coverlay:
Shield Layer
Layer 4 Base Copper um + Plated 25 um min.
FR-4 (170 tg min.)
FR-4 (170 tg min.)
Prepreg (2 x 1080 no flow)
Prepreg (2 x 1080 no flow)
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Summary
The combination of todays Rigid PCB and Flex circuit technology allows for a very wide variety of Rigid-Flex constructions that can add a significant amount of functionality, integration and overall packaging reduction to a design.
Majority of the specific constructions can also be combined together to create an almost endless number of configurations.
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Our Products
Custom Battery Packs Flex & Rigid-Flex PCB’s High Reliability SMART HMIs
RF Product Solutions Cable Assemblies Printed Circuit Boards
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Design Centers & Technical Support
Battery Pack & Power Management – Denver, CO
SMART User Interfaces – Largo, FL
Flex & Rigid Flex – Toronto, Canada
RF Products – New Bedford, MA & Largo, FL
Cable Assemblies – Largo, FL
Printed Circuit Boards – New Bedford, MA & Shenzhen, China
Our Engineering and Design teams are ready to help our customers create world class and cost effective product solutions.
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Q&A
Questions?
– Enter any questions you may have in the Control Panel
– If we don’t have time to get to it, wewill reply via email
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Thank YouCheck out our website at www.epectec.com.
For more information email [email protected].
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