Counterbore Hole PCB

A 4-layer PCB on S1000H high-Tg laminate at 1.6±0.16mm thickness with ENIG surface finish, machined with counterbored mounting holes that recess fastener heads below the board surface. Counterbore drilling is performed in two depth passes so the larger upper-section bore clears the screw or rivet head while the lower through-hole guides the shaft, producing a flush-mount finish that prevents fastener interference with adjacent components, enclosures, or stacked PCB assemblies. Typical applications include connectorized industrial-control boards, automotive ECU mounting plates, instrumentation chassis boards, and rack-mounted telecom and consumer assemblies where mechanical clearance and uniform top-surface profile matter for assembly fit and long-term contact pressure on chassis grounds.