holes

[gbowne1]

The most commonly used PCB mounting hole types and sizes are:

Type: Through-Hole
    Size: Common diameters are 2.5 mm (0.1 inch), 3.0 mm (0.125 inch), and 3.2 mm (0.126 inch).
    Usage: Typically used for securing the PCB to a chassis or enclosure.

Type: Counterbore Holes
    Size: Often 3.2 mm (0.126 inch) for the hole, with a counterbore diameter of about 5.0 mm (0.2 inch) to accommodate a screw head.
    Usage: For flush mounting of screws.

Type: Countersink Holes
    Size: Usually 3.2 mm (0.126 inch) with a countersink angle of 82 degrees or 90 degrees.
    Usage: For flush mounting with a countersunk screw.

Type: Edge Mount Holes
    Size: Commonly 2.5 mm (0.1 inch) or 3.2 mm (0.126 inch) placed along the edge of the PCB.
    Usage: For mounting the PCB to a panel.