how to design flexible PCBs - Tips from QualiEco Canada

Technical Articles

Flexible PCBs (Part III) – Design Tips for Effective PCB Manufacturing and to Improve Product Quality

Know Your Application and Frequency of Usage

Before you design a flexible PCB, it is very important that you know what kind of bending flexibility is expected from the PCB in the application and during usage – Dynamic Bend, Semi-Dynamic Bend or Stable Bend. Following is a guide to help you decide this -

Criteria	Dynamic Bend	Semi-Dynamic Bend	Stable Bend
Frequency of Bending	Regular	Moderate	Once or Few Times (e.g. during installation)
No. of Layers	1 Layer (min) 2 Layer (max)	1 Layer (min) 4 Layer (max)	1 Layer (min) 10 Layer (max)
Mask Layer	PI Coverlay	PI Coverlay or Solder Resist	PI Coverlay or Solder Resist
Min. Bending Radius	100-150 times flex PCB thickness	More than 20 times flex PCB thickness	10-20 times flex PCB thickness

Conductor Routing – Design Tips

Avoid Right Angle & Hard Corners

Maximise Line Widths

Avoid I-Beam Design

Add Tear Stops

Ground Planes – Design Tips

Convert Continuous Solid Copper into Hatched Pattern

Pads, Vias & Coverlay – Design Tips

Anchor Spurs & Add Fillets

Design Elongated Pads Instead of Traditional Round Pads

Add Coverlay Support to PTH & NPTH holes

Add Coverlay Support to SMD Pad

Bending Area – Design Tips

Rout Conductor Traces Perpendicular to Bending Axis

Bending Area – Design Tips

Divide Wide Traces Into Few Narrower Ones

Fill Open Regions with Fake Traces

Do Not Change Conductor Width Abruptly

Avoid Vias & Component Pads

Slots & Cut Out – Design Tips

Contract Assembly

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