4 Layer Flexible PCB Production Record #FPC-20260707-032

This production record covers 125 units of 4-layer flexible PCBs built on 0.2 mm polyimide with 1/3 oz rolled copper. The boards measure 157.2 × 38.6 mm and incorporate 3/3 mil trace and spacing, a yellow solder mask, white silkscreen, PI stiffeners, and immersion gold ENIG finish. Minimum hole size of 0.3 mm was maintained across the thin construction, requiring precise material handling to preserve flexibility while meeting the tight geometry.

We performed inner layer imaging, circuit etching, high-pressure lamination, and coverlay application under controlled conditions to ensure layer registration and mechanical stability. Electroless nickel and immersion gold deposition followed solder mask processing, delivering uniform plating on the fine features. Dynamic flex testing was conducted to verify endurance, while 100 % electrical testing confirmed net continuity and isolation.

The entire run was completed in 16.4 days with consistent results across all boards, demonstrating repeatable execution for thin, high-density flexible circuits that require both precision etching and reliable mechanical performance.