8 Layer Through Hole PCB Assembly For Medical Devices

Medical-grade 8-layer through-hole immersion gold and blue oil solder mask, controlling high aspect ratio perforation, gold layer density, and blue oil insulation performance. The board is 1.6mm thick with an 8:1 aspect ratio. Drilling utilizes a double-sided drilling process, ensuring no glass cloth protrusion on the hole walls and a roughness ≤18μm. Electroplating requires highly dispersing additives, with an internal copper thickness ≥20μm and a tolerance ≤4μm, and a copper thickness ratio at the hole opening to the bottom ≤1.5:1. Plasma cleaning is performed before immersion gold plating, ensuring a dense, microporous gold layer. Salt spray testing shows no corrosion for ≥96 hours, and the internal stress of the nickel layer is controlled between 80-120MPa. The blue oil requires high insulation, with a dielectric strength ≥40kV/mm. After development, high-pressure water washing removes residue, followed by curing at 150℃ for 70 minutes. Each batch undergoes CAF testing (100V, 85℃/85%RH, 500h), with an insulation resistance ≥100MΩ. Ion contamination ≤0.3μg/cm², no stratification observed in ultrasonic scanning after thermal shock, and full-process MES recording.