In high-precision PCB manufacturing, selecting the right drilling and plating techniques is essential for both mechanical fit and electrical performance. This guide covers four critical advanced processes: Countersinks, Plated Half-Holes, Edge Plating, and Resin Via Filling.

1. Countersink & Counterbore Holes

Deep-controlled drilling allows screws to sit flush with or below the board surface.

• Types: Available in Conical (Countersink) and Cylindrical (Counterbore) shapes.

• Plating: Can be processed as PTH (Plated Through Hole) or NPTH (Non-Plated Through Hole).

• Standard Angles: 90° is most common, but 82°, 100°, and 120° are available to match specific hardware.
  

2. Plated Half-Holes (Castellated Holes)

Plated half-holes are semi-circular holes located on the edge of the PCB, allowing one board to be soldered directly onto another (mother-daughter board design).

• Manufacturing Tip: We strongly recommend ENIG (Electroless Nickel Immersion Gold) surface finish for boards with half-holes. Process techniques like HASL increase the risk of copper lifting or burrs during the routing process.
  
  

3. Edge Plating

Edge plating involves copper plating the vertical edges of the PCB.

• Applications: It is primarily used to enhance EMI/EMC shielding, establish a robust chassis ground, and improve heat dissipation across the board edges.

4. Resin Via Filling 

This process involves filling vias with a specialized non-conductive epoxy resin, followed by planarization and copper capping (often called "Via-in-Pad").

• Why use it? It ensures the via is 100% filled and flat, preventing solder wicking (leakage) and air bubbles during assembly. This is a mandatory requirement for high-density BGA designs.
  
  

Conclusion

Understanding these specialized PCB features helps ensure your design is manufacturable and reliable. If you have specific requirements for your next project, contact our engineering team for a technical review.

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