4 Layer Flexible PCB Production Record #FPC-20251210-0117

This run produced 15 four-layer flexible PCBs on 0.23 mm rolled copper polyimide, each measuring 10.91 × 451.8 mm. The 2/2 mil trace and spacing geometry demanded exact imaging and etching control on the thin substrate, while the long narrow format required precise layer stack alignment during high-pressure lamination and coverlay processing. Yellow soldermask, white silkscreen, and immersion gold ENIG finish were applied to meet both electrical and visual requirements without stiffeners.

Stackup impedance engineering and trace width compensation were performed prior to circuit imaging to maintain target impedance across the extended length. Material preparation and polyimide handling followed established flex protocols, with electroless nickel and immersion gold deposition completing the surface. The sequence concluded with TDR impedance testing and dynamic flex testing to validate performance under repeated bending.

All 15 boards passed electrical testing after 17.3 days of controlled production, confirming consistent impedance and trace integrity. The executed process delivered reliable flexible circuits suited to the tight geometry and mechanical demands of this order.