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© 2015 HDP User Group International, Inc. All rights reserved Project Proposal/Scope Of the three areas of concern the team has decided to conduct a study to characterize the effect on signal integrity for flexible printed circuit boards operating at high end digital transmission frequencies with regards to: Different design features: Various Crosshatched ground plane designs Material choice: Polyimide (DuPont/Panasonic) Laminate thickness: 100 um Frequency ranges up to 20 Ghz S parameter performance analysis (Insertion & Return Loss and Impedance) of FPC test vehicles Comparison of measured results vs. models 3
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High Frequency Flex ProjectDefinition Phase
Project Lead: TBDProject Facilitator: John Davignon, HDPUG
HDP User Group Member Meeting Santa Clara, CA Feb 10-11, 2016
Problem Statement
© 2015 HDP User Group International, Inc. All rights reserved
Flexible printed circuits (FPCs) provide a practical option for interconnection of printed circuit boards and electronic modules. Moreover FPC construction offers greater levels of impedance control compared with co-axial and other wired connections. However with FPCs increasingly being used in high speed digital applications, understanding their electrical performance at high frequencies becomes a growing challenge. Differences between measured results and present models have been seen. Several issues arise from using them for this purpose.
1. Controlling the critical geometries of flexible materials as they differ from rigid PWBs.
2. The differing properties of the materials (Dk, Df etc.) involved and the fact that some dielectrics and adhesives are very hygroscopic.
3. Cross hatch GND planes. Simulating the effect of the non-contiguous plane and the effect of various shapes. Cross hatch GND Planes used for Flexibility & Impedance control
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© 2015 HDP User Group International, Inc. All rights reserved
Project Proposal/Scope
Of the three areas of concern the team has decided to conduct a study to characterize the effect on signal integrity for flexible printed circuit boards operating at high end digital transmission frequencies with regards to:
• Different design features: Various Crosshatched ground plane designs
• Material choice: Polyimide (DuPont/Panasonic)• Laminate thickness: 100 um• Frequency ranges up to 20 Ghz• S parameter performance analysis (Insertion & Return Loss
and Impedance) of FPC test vehicles• Comparison of measured results vs. models
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DOE/Objectives
© 2015 HDP User Group International, Inc. All rights reserved
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• Design a test vehicle using a Solid Plane as the reference feature and various cross hatch designs.
• Run with a series of frequencies up to 20 GHz and see the effect on impedance/loss. Would need TDR and S parameters.
• Evaluate how the cross hatch designs effects impedance and S parameters (insertion and return loss)
• Overlay the response on a plot and evaluate how much they are different or change.
• Compare model to measured results
Deliverables
© 2015 HDP User Group International, Inc. All rights reserved 5
• Publish a comparison of measured SI data to present model predictions
• Publish guidelines on crosshatch design findings
• Publish final report to members• Present finding at industry conference
(EIPC/IPC APEX) • Recommendation for the next phase of work
Benefits
© 2015 HDP User Group International, Inc. All rights reserved
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This project will provide the industry with the fundamental knowledge of the mechanical/design and electrical properties differences between flex and rigid products. Provide important knowledge of why the present models do not match the performance being measured.
Provide better methods to design with flex going forward.
Provide an understanding of the effects of crosshatching design and how to improve the design.
Status
© 2015 HDP User Group International, Inc. All rights reserved 7
• Team focused on replacing Project Lead and loss of Polar Instruments
• Flex Laminate Materials and thickness have been decided
• Frequency test range has been decided• Coupon designs are underway • Project still open to new participants and presently
seeking project resources• CAD Designer help for coupon/layout (Ciena)• Additional Flex Fabricator• Additional test house (SPP - Introbotix)• 3D simulation capabilities
TV Stack-up
© 2015 HDP User Group International, Inc. All rights reserved
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25 um Low Modulus PI Constant - used for both DuPont and Panasonic builds25 um Acrylic Adhesive
18 um 0.5 oz RA Cu
50 um High Modulus PI Panasonic R-F775 .002"RAH/RAH
18 um 0.5 oz RA Cu
25 um Acrylic Adhesive
50 um Low Modulus PI Constant - used for both DuPotn and Panasonic builds
25 um Acrylic Adhesive
18 um 0.5 oz RA Cu
100 um High Modulus PI Panasonic R-F775 .004"RAH/RAH
18 um 0.5 oz RA Cu
25 um Acrylic Adhesive25 um Low Modulus PI Constant - used for both DuPotn and Panasonic builds
LF0110 Coverlay
AP8525R Core
LF0121 Bondply
AP8545R Core
LF0110 Coverlay
Flow Chart
© 2015 HDP User Group International, Inc. All rights reserved 9
MaterialsHatched Plane TV Design
Fabricate TV Test
Select Laminate Materials
Procure Materials
PanasonicDuPont
ImpedanceLoss
–DuPont/Introbotix
Design TV w/ Gerber files
M-Flex
Fabricator(s)TTM
DOE Definition
Downselect Objective/Goals
3D Simulations –MFlex
2D Simulations - TBD
Finalize Test coupon designsDuPont/ Ciena
Analyze DataDuPont/Nokia
Write ReportTBD
Present Report Close Project
Resource & Schedule
© 2015 HDP User Group International, Inc. All rights reserved 10
Task Owner Planned Schedule
Actual Schedule
DOE Definition Polar Q4’ 15 Completed
Design TV coupons Polar Q4’ 15 In-progress
Generate Gerber/Design Files
M-Flex / Ciena Q1’ 16
Procure TV laminate DuPont / Panasonic
Q1’16
Fabricate TV TTM Q2’16
Test - Measure Coupons
DuPont / Introbotix
Q3’16
Analyze Data / Compare Si to Models
DuPont / Nokia-US
Q3’16
Write Report Team Q4’16
Present / Publish Findings
Team Q4’16
Project Participants
© 2015 HDP User Group International, Inc. All rights reserved 11
DuPont EngentIBMM-Flex –Non-MemberMicroConnex – Non-MemberNokia-USPanasonicRogersTTM
High Frequency Flex
© 2015 HDP User Group International, Inc. All rights reserved
Potential Project Partners
Input is still welcome from HDP User Group members who can contribute. In particular, a CAD designer, additional Flex fabricator and test houses/test equipment providers would be desirable for the project to deliver maximum benefit.
Contact : John Davignon, HDP Project Facilitator at [email protected].
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