4 Layer Flexible PCB Production Record #FPC-20251120-0002

This four-layer flex circuit board order required production of 20 elongated boards measuring 28 × 172.2 mm at an overall thickness of 0.23 mm. Rolled copper at 1/3 oz weight was used on polyimide material to preserve flexibility, paired with standard 6/6 mil track and spacing, 0.3 mm minimum holes, black soldermask, white silkscreen, and immersion gold ENIG finish. The absence of stiffeners kept the design fully dynamic while the narrow aspect ratio demanded precise registration throughout the multilayer stack.

We performed careful polyimide material handling, inner layer imaging, and circuit etching prior to high-pressure lamination and coverlay application. Solder mask processing was adjusted for the thin flexible substrate, followed by electroless nickel and immersion gold deposition that produced a uniform, oxidation-resistant surface. Dynamic flex testing validated mechanical endurance under repeated bending, while 100 % electrical testing verified continuity on every unit.

All 20 boards were delivered within the 10-day schedule with consistent quality and no rework required. The executed process sequence demonstrates reliable multilayer flexible PCB manufacturing for applications that combine thin construction, ENIG surface, and dynamic mechanical demands.