Custom 6 Layer Medical PCB Manufacturing With Black Solder Mask Through Hole Technology

Medical-grade 6-layer through-hole solder-free black solder paste board, with strict control over the uniformity of the solder layer, the integrity of the black solder paste coverage, and medical-grade cleanliness. Drilling process burrs ≤10μm, hole wall roughness ≤20μm, backlight ≥9 level. Before soldering, low flux residue verification is performed, ion residue ≤0.1μg/cm², vertical soldering line speed 1.0m/min, air knife pressure 0.4-0.6MPa, solder thickness 2-6μm, ≥2μm at leads, no exposed copper, no icicles, and no solder nodules inside the holes. Black solder paste requires two screen printings, thickness ≥20μm, exposure energy 12-15% higher than green solder paste, development point controlled at 40-46 seconds, full inspection of pinholes under UV light, post-curing stepped temperature rise of 80→120→150℃ for 30 minutes each for explosion-proof holes. After thermal stress of 288℃×10s, no bubbling or cracking of the black solder paste, and the copper elongation of the holes ≥12%. Ion contamination ≤0.3μg/cm², solderability test for each batch with a solderability rate ≥98%, and medical-specific traceability code engraved on the entire board.