Double Side Countersink Hole PCB for Consumer Electronics

A Countersink Hole PCB is a printed circuit board whose mounting or component holes are machined with a conical flare at the top, allowing flat-head screws or connectors to sit flush with (or slightly below) the board surface instead of protruding.

• Geometry
  • A two-step hole: the smaller pilot hole goes through the board, while the larger conical section is cut to a specific angle--typically 82°, 90° or 120°--so the screw head matches the taper.
• Purpose
  • Eliminates screw-head stand-off, saving vertical space and preventing short circuits to nearby enclosures or shields
  • Improves mechanical strength by distributing clamping force over a larger bearing area
  • Gives a neat, planar appearance for card-edge guides, front panels or RF shields
• Design parameters
  • Major diameter (D2): the top countersink diameter, chosen to clear the screw head
  • Minor diameter (D1): the drilled hole for the screw shank or plated via
  • Depth (h): usually controlled to leave ≥ 0.2 mm of PCB material below the taper to avoid breakout
  • Angle (θ): must match the screw head angle (common metric/Imperial screws use 90°)
• Manufacturing
  • Done after normal drilling but before plating: a precision CNC cutter or secondary drilling station forms the cone; burrs are removed and the board is cleaned before electroless copper
  • If the countersink intersects a plated via, the via is plugged or tented to prevent solder leakage during reflow
• Typical applications
  • Edge-mounted connectors, power devices secured with flat-head screws, RF modules, LED boards that must sit flush against heat-sinks, or any assembly where height clearance is critical