4 Layer FR4 PCB Production Record #FR4-20260106-056

This 4-layer FR-4 board (120 × 122 mm, 1.6 mm finished thickness, TG150 KB-6165F material) was produced as single-unit panels for a quantity of 10 pieces. It featured 1 oz copper on all layers, 3 mil minimum line/space, 0.2 mm minimum hole size, green solder mask, white legend, and ENIG surface finish. The order required impedance control and 100% flying probe testing with V-scoring for final separation. The tight geometries and controlled impedance made this a fine-line multilayer build.

DFM review highlighted several specification conflicts that needed resolution. Requested impedance lines of 5/5 mil for 90 ohms were not located in the files; we identified actual differential pairs and adjusted trace widths and stackup to meet the target impedance. Outer copper thickness requirements (35 ±10% µm) conflicted with the fine 3/3 mil geometries and standard 1 oz foil, so we confirmed achievable values. Solder mask bridge capability was limited on 5 mil pad spacings with 1 oz copper; we clarified acceptance criteria for potential bridge loss. Additional issues addressed included inconsistent drill tolerances, PTH hole definitions on non-connected equal-size pads, missing process tooling holes, character placement near pads, and solder mask opening on specific vias. impedance control and solder mask bridge handling were managed through customer-confirmed adjustments and file revisions.

All engineering questions were resolved prior to production release. The order completed within the 10-day delivery window using mechanical forming. Final electrical testing and quality documentation confirmed compliance with the adjusted parameters and controlled processes.