Reliability is a significant consideration in all designs, but more so in specific industries. The costs of either initial failures during assembly or more critically latent in the field failures can be excessive in both the expense and consequences. A benefit of rigid-flex technology is the ability to improve the reliability of a design. This applies to both the electrical functionality, and more importantly, the mechanical performance of the finished parts. Mechanically, reliability is improved in two areas: the elimination of many points of interconnect between multiple rigid sections and a reduction in the total weight for improved shock and vibe performance. Electrically, rigid-flex designs allow for both improved signal integrity, for high-speed controlled impedance requirements, and effective shielding for EMI and RF sensitive designs. In this webinar we review the multiple aspects of rigid-flex technology that will improve the reliability of your designs. For more information on our rigid-flex PCBs, visit http://www.epectec.com/flex/.

1. Manufacturing That Eliminates Risk & Improves Reliability
Utilizing Rigid-Flex PCBs to
Improve Design Reliability
02.21.2020

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Agenda
 Mechanical Reliability:
– Points of Interconnect
– Shock & Vibe Performance
– Minimum Bend Capabilities
– Durability
 Electrical Reliability:
– High Speed Signals
– EMI / RF Shielding
 IPC 2223 Guidelines for Reliable Constructions

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Introduction

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 Definition: Reliability
– Ability of an apparatus or system to consistently perform its required function
without degradation or failure.
 Reliability engineering studies identified:
– “Majority of electronic failures occur at a point
of interconnect.”
 Critical to many Class 3 applications
– Military
– Aerospace
– Life-supporting medical
– Automotive
Introduction

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Introduction
 Cost Benefits
– Improved final assembly yields.
– Eliminates latent, in the field, failures, and associated product return and or
replacement.
– Opportunity to offset added rigid-flex solution costs.
– Securing repeat business.

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Mechanical Reliability:
Points of Interconnect

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Mechanical Reliability: Points of Interconnect
 Interconnects are potential sources of failure.
 Rigid-flex is deemed to be an integrated construction.
 Eliminates all points of interconnect between
independent rigid component areas.
 No additional interconnects required between flex and
rigid layers.
 All connections are plated vias/holes with same
reliability as rigid PCBs.

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Mechanical Reliability: Points of Interconnect

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Mechanical Reliability: Points of Interconnect
 Example
– Standard “wired” solution:
• Up to 6 interconnect points for each circuit.
• PCB to connector solder joints (2).
• Header to receptacle connections (2).
• Wire to receptacle connections:
– Soldered or crimped (2).
 Added Benefit
– Reduces potential assembly errors.
– Cannot be assembled incorrectly.

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Mechanical Reliability:
Shock & Vibe Performance

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Mechanical Reliability: Shock & Vibe
 Reduced Weight
– Improved shock & vibe performance.
– Weight = approx. 20% or less of a wired solution.
 Impact dependent upon length of flex section(s)
– Longer the flex, the greater the weight savings, the
greater the improvement.
 Flex sections easily attached/strain relieved to
enclosure with pre-attached PSAs (double sided tape).
 Material ductility & flexibility reduces impact of shock & vibration
events.

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Mechanical Reliability:
Bend Capabilities

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Mechanical Reliability: Bend Capabilities
 Thinner flex constructions allow for:
– Tighter bend capabilities due to:
• Thinner copper circuit layers.
• Thinner core & insulating layers.
– Min. bend radius capability guidelines:
• Function of finished flex thickness:
• Static Bend: 10-30 X
• Dynamic Bend: 80-100 X
– Less potential induced stress in the bend areas as
compared to bulkier wired solutions.

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Mechanical Reliability:
Durability

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Mechanical Reliability: Durability
 Polyimide Materials
– Excellent resistance to wide range of chemistries
and environments:
• Acids, Basics, Solvents, Gasses
• UV exposure
• Radiation exposure
• Temperature
– Abrasion resistant
– Long life mechanical properties
– High dielectric strength: > 5 KV per 0.001”

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Electrical Reliability:
High Speed Signal Performance

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Electrical Reliability: High Speed Signal Performance
 Flex circuit materials and constructions inherently
well-suited to high speed signal applications.
– Highly uniform material thicknesses.
– Improved DK values over standard rigid materials.
– Uniform line width and spacings.
– Eliminates signal reflections due to connector systems.
• Added benefit:
– Eliminates high-cost controlled impedance connector
systems.

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Electrical Reliability: High Speed Signal Performance

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Electrical Reliability:
EMI / RF Shielding

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Electrical Reliability: EMI / RF Shielding
 Flex can easily and effectively be shielded to high levels against EMI & RF.
 Multiple shielding methods available:
– Flex specific shielding films
• Preferred solution for shielding only requirements
• Highly flexible, slip properties

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Electrical Reliability: EMI / RF Shielding
– Addition copper shield layers
• Necessary for controlled impedance applications
– Silver ink shield layers
• Replaced by shielding films

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IPC 2223 Design Standard:
Reliability Guidelines

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IPC 2223 Design Standard: Reliability Guidelines
 Released: 1998
 Established specific design, material, and structure
requirements for flex & rigid-flex circuits.
 Collaborative program between:
– IPC, material suppliers, manufacturers.
– Address developing plated hole reliability concerns
in flex and rigid-flex due to increased design
complexity.
Ebook Download:
https://info.epectec.com/guides/ipc-2223-design-standard-for-flex-and-rigid-flex-circuits

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IPC 2223 Design Standard: Reliability Guidelines
 Materials
– Adhesiveless flex materials
 Construction / Manufacturing
– Selective flex coverlay
– Pre-preg only laminations
– Air gap constructions
 Design
– Min. via/plated hole spacing to flex
transition(s)
– Min. bend capability guidelines
• Static & dynamic
Transition Zone

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IPC 2223 Design Standard: Reliability Guidelines

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Summary
 Design Reliability
– Critical element of all projects.
– Consequences of a failure in Class 3 products require every effort to ensure highest
possible reliability.
 Rigid-flex Technology Improves
– Reliability:
• Significant reduction in points of interconnect/failure locations.
– Performance:
• High Speed Signals & Shielded Designs.
– Durability in harsh environments.
– Shock & vibe performance through weight reduction.

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Summary
 IPC 2223 Design guidelines
– Must be followed to ensure finished part reliability.
 Added Benefits
– Smaller/tighter packaging requirements.
– Cost-savings opportunities:
• Reduced/simplified assembly requirements.
• Overall packing size reduction.
• Purchasing/inventory management costs.

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Our Products
Battery Packs Flex & Rigid-Flex PCBs Cable Assemblies Printed Circuit Boards
RF Products User Interfaces Flexible Heaters EC Fans & Motors

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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, we
will reply via email

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Thank You
Check out our website at www.epectec.com.
For more information email sales@epectec.com.
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