Coverlay on PCB RFQ Bloghttps://blog.pcbrfq.com/tags/coverlay/Recent content in Coverlay on PCB RFQ BlogHugo -- gohugo.ioen-us© 2026Wed, 20 May 2026 00:00:00 +0000Polyimide Flex PCBs — Chemistry, Coverlay, and Why Flexible Solder Mask Is Not the Same Thinghttps://blog.pcbrfq.com/posts/polyimide-flex-coverlay-solder-mask/Wed, 20 May 2026 00:00:00 +0000https://blog.pcbrfq.com/posts/polyimide-flex-coverlay-solder-mask/<p>Flex PCB specifications are among the most frequently underspecified documents in electronics procurement. Buyers write &ldquo;flex PCB, polyimide base&rdquo; and assume the supplier will fill in the rest correctly. Sometimes they do. Often they do not — and the failure mode is a board that cracks, delaminates, or develops intermittent opens after a few thousand flex cycles.</p> <p>Understanding why polyimide behaves the way it does, and why the protective layer choices matter as much as the base material, is the foundation of a correct flex PCB specification.</p>