Designing flex PCBs for high-temperature (>125°C) applications presents challenges like thermal stress and trace delamination. You can overcome these issues by selecting materials with compatible CTEs and using reinforcing elements like stiffeners.

In this article, you will learn 6 common challenges in building heat-resistant flex PCBs and ways to overcome them.

Highlights:

• Use thermally conductive adhesives and consider adhesiveless laminates.
• Choose dielectric materials with high-temperature stability.
• Maintain proper bend radius, stagger traces, use cross-hatched ground planes, and incorporate stiffeners wherever necessary.
• Perform thermal shock, burn-in, and mechanical stress tests to validate flex PCB performance under extreme conditions.

A quick guide for selecting high-temperature flex materials

FPCs are typically made up of flex cores, copper films, coverlays, and adhesives to bond these together. Some designs may also include stiffeners for component support and pressure-sensitive adhesive (PSA) for attachment.

All standard flex materials can withstand temperatures from ~40 °C to 85 °C. For high temperatures exceeding 85 °C, specialized materials and construction methods are necessary. The table below serves as a guide to select flexible circuit materials for high-temperature applications.