rigid-flex circuit board gerber layout guidelines webinar
Post on 01-Jun-2015
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DELIVERING QUALITY SINCE 1952.
Rigid – Flex Circuit Gerber Layout Guidelines
05.30.14
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Rigid – Flex circuits introduce additional design requirements which need to be accommodated at the Geber Layout phase:
– Rigid to Flex Transition Lines
– Layer Stack ups
– Trace Layout in Flex Areas
Introduction
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Introduction
Guidelines based on IPC 2223C recommended Rigid – Flex Construction(s):
– Ensures the highest degree of reliability and performance
– Key Elements• Adhesiveless Flex Core
• Selective Flex Area Coverlay
• No Flow Prepreg (rigid area layer lamination)
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Definition: Line at which flex layers exit from Rigid area(s)
– Special requirements due to:
• IPC 2223C Selective Coverlay and Material Guidelines
• Manufacturing Methods:
– Rigid Materials (FR4 & Prepreg) are removed from flex areas prior to the layer lamination process
Rigid to Flex Transition Lines
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Rigid to Flex Transition Lines:PTH Hole Spacing
0.050” Min. Requirement:– As measured from edge of drilled hole to “Rigid to Flex” transition line(s)
– Prevents PTH holes from being drilled through Selective Coverlay adhesives
– Accounts for manufacturing and material tolerances
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Rigid to Flex Transition Lines:Copper Feature Spacing
0.025” Min. Clearance (External Layers only)– Allows for manufacturing methods and tolerances during outer layer
imaging processes
– Accounts for prior removal of rigid materials in flex areas
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Rigid – Flex Layer Stack Up Guidelines
Flex Layer Core Thickness(s):
– 0.001” recommended• Improved flexibility, mechanical reliability and bend radius capability
– 0.002” to 0.003” required for impedance controlled designs
Balanced Construction with centrally located Flex Layers Recommended:
– Minimizes potential warp and twist in assembly arrays
– Avoids potential cost adders
– Unbalanced builds possible but should be reviewed with supplier in advance
Balanced Construction Unbalanced Construction
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Rigid – Flex Layer Stack UpGuidelines
Same Finished Thickness in all Rigid Areas:– Avoids sequential lamination processes and significant added costs
– Consult with supplier to determine viability
Odd Layer Counts Allowed:
– E.G.: 5 Layer Rigid with 1 or 3 layers flex etc.
Flex Area Layer Count:– Minimize for thinnest possible construction
• Improved flexibility, reliability and bend radius
Flex Layer Copper Weight:– ½ OZ Copper recommended
• Improved flexibility and mechanical reliability• Allows for impedance controlled circuits
– 1 OZ Copper available for higher current carrying requirements
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Rigid – Flex Layer Stack UpGuidelines
Paired Flex Layers Structure Recommended:– Eliminates flex adhesives from rigid areas for PTH reliability
– Improves flex area flexibility and mechanical reliability
8 Layer Rigid – 2 Layer Flex 8 Layer Rigid – 4 Layer Flex (Air Gap)
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Rigid – Flex Layer Stack UpGuidelines
Impedance Controlled / Shielded Designs:– May require 3 or more flex layers bonded together
– Use of flex adhesives to be minimized to best conform to IPC 2223C
– Potential negative impact on flexibility and bend requirements
– Consult with supplier for best configuration
7 Layer with 3 Flex Layers 8Layer with 4 Flex Layers
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Flex Area Trace Layout Guidelines
Offset Traces from Layer to Layer in Flex Area (if possible)– Improves mechanical flexibility by minimizing “I-Beam” effect
– Impedance Controlled and Shielded Designs will not fully allow due to reference plane requirement
Preferred Not Recommended
Impedance Controlled Design
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Flex Area Trace Layout Guidelines
Straight / Parallel Trace layout is preferred:– Eliminates potential mechanical stress concentrators in bend areas
– If direction change is required then rounded trace corners are recommended
• Up to 45 degree corners are allowed
• 90 degree corners are not recommended
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Our Products
Battery Packs Flex & Rigid-Flex PCB’s User Interfaces
Fans & Motors Cable Assemblies Printed Circuit Boards
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Design Centers & Technical Support
Battery Pack & Power Management – Denver, CO User Interfaces – Largo, FL Fans & Motors – Wales, UK PCB’s – New Bedford, MA & Shenzhen, China Flex & Rigid Flex – Toronto, Canada Cable Assemblies – New Bedford, MA
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 previous webinars at www.epectec.com.
For more information email sales@epectec.com.
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