4 Layer Flexible PCB Production Record #FPC-20260416-083

This production record covers 1000 units of 4-layer flexible PCBs built on polyimide with 1/3 oz rolled copper. Measuring 357 × 45.8 mm and only 0.23 mm thick, the boards required careful material handling to preserve flexibility while achieving reliable multilayer registration. Specifications included 6/6 mil trace spacing, 0.3 mm minimum holes, black soldermask, white silkscreen, immersion gold ENIG finish, and steel sheet stiffeners selectively applied for component support.

Manufacturing followed a sequence of polyimide preparation, inner layer imaging, precise layer stack alignment, and high-pressure lamination. Coverlay lamination preceded solder mask application and the electroless nickel and immersion gold deposition steps. These processes were tuned to maintain dimensional stability across the long, narrow panels without inducing stress in the thin construction.

Dynamic flex testing, batch AOI inspection, and full electrical testing confirmed consistent performance throughout the run. All boards met the specified electrical and mechanical requirements, completing the order in 22.2 days with stable yield and repeatable quality for this multilayer flex configuration.