4 Layer Flexible PCB Production Record #FPC-20251107-0009

Production of this 4-layer flexible printed circuit board order involved 30 boards measuring 25.1 × 101.1 mm with an overall thickness of 0.23 mm. The stackup used ½ oz rolled copper on polyimide material together with FR4 stiffeners in selected zones. Minimum 2/2 mil trace and spacing demanded precise inner layer imaging, etching, and trace width compensation to preserve geometry on the thin construction, while yellow soldermask, white silkscreen, and immersion gold ENIG provided the required surface finish.

Stackup impedance engineering was completed prior to high-pressure lamination and coverlay application. We performed TDR impedance testing after electroless nickel and immersion gold deposition to confirm signal integrity across the batch. Dynamic flex testing verified mechanical endurance under repeated bending, and polyimide material handling was strictly controlled to avoid wrinkles or delamination in the 0.1 mm minimum holes and fine features.

Full electrical testing confirmed every board met specifications, delivering consistent performance for this impedance controlled flexible PCB. The 41-day manufacturing cycle reflected the thorough validation required by the tight geometries and flex durability demands.