Background Theory > PCB Design > PCB Finished Hole Size Tolerances

Finished hole size tolerances refer to the acceptable variation in the final dimensions of drilled holes in a printed circuit board (PCB) after all manufacturing processes are complete. This includes not just the drilling of the hole, but also any plating or coating processes that might affect the hole's final dimensions.

Hole size is an essential parameter in PCB design because it directly impacts the fit of through-hole components and the alignment of vias connecting different layers of the board.

The specific values of the finished hole size tolerances can vary depending on the manufacturer and the specific manufacturing processes used. However, for standard PCB manufacturing processes, typical tolerances might look something like this:

Finished Hole Size Tolerance (PTH, Plated Through Hole)

This is typically around ±0.003" to ±0.005" (±0.075mm to ±0.125mm).

Finished Hole Size Tolerance (NPTH, Non-Plated Through Hole)

This is often a bit tighter, around ±0.002" to ±0.003" (±0.05mm to ±0.075mm) as there is no plating process involved that could change the hole size.

For smaller holes, such as those used for microvias in high-density interconnect (HDI) boards, the tolerances can be much tighter. For these, laser drilling is often used and the typical tolerance might be around ±0.0005" (±0.013mm).

As always, it's important to check with your specific PCB manufacturer for their capabilities, as achieving precise hole sizes may involve additional costs. It's also crucial to ensure that your PCB design can accommodate these tolerances to ensure proper fit and function of components and connections.