PTH vs. NPTH: Specify PCB Holes Without Guesswork

A hole used for a screw and a hole used for a component lead can look similar in a preview while requiring different fabrication treatment. PTH means plated through hole; NPTH means non-plated through hole. State the intended treatment explicitly instead of expecting the manufacturer to infer it from the drawing.

Decide what each hole must do

Group holes by function: component leads, electrical vias, locating pins and mechanical fasteners. A mounting hole is not automatically NPTH; some designs intentionally connect mounting hardware to a net. That connection is an electrical design decision and should be visible in the source layout and supporting drawing.

Eurocircuits' drilled-hole guidelines distinguish plated holes, non-plated holes and vias, and describe using separate drill outputs for PTH and NPTH. Its tool adjustments and tolerances apply to its own process. For a DIYIPCB order, request confirmation of the applicable finished-hole tolerance for critical fits.

Specify the finished feature

A connector must fit the finished hole after manufacturing. Record the required finished diameter, its allowed tolerance and any mating-part constraints. Do not enlarge the CAD hole by an assumed plating allowance without discussing the convention with the fabricator; that can apply compensation twice.

For an illustrative connector review, list the maximum lead dimensions from the exact package drawing, the intended hole specification and the required insertion clearance. Leave a visible unresolved item if those dimensions do not establish a reliable fit. A nominal lead diameter alone is not enough to accept the footprint.

Make the drill package unambiguous

• Export PTH and NPTH separately when the CAD workflow supports it.
• Name files clearly and include a short drill legend.
• Highlight press-fit or otherwise critical holes on a dimensioned drawing.
• Identify mechanical holes that intentionally connect to copper.
• Verify the drill overlay against pads and the board contour.

Resolve conflicts before release

If the drawing says NPTH while the drill data identifies a plated feature, revise the package so both agree. A note in a purchase message should not become a permanent substitute for corrected source data. Keep the accepted hole specification with the release, especially when changing connectors or reordering from a different fabrication process.

Technical reference: Eurocircuits: drilled-hole definitions. Supplier-specific process limits in the reference are not DIYIPCB manufacturing commitments.