The Common types of holes in PCB

Non metalized through-hole (NPTH)

There is no copper deposition on the inner wall of this hole, and there is no electrical connection during use. Mainly used for positioning during electronic component assembly, it can also be used for connecting seams during typesetting.

Metallized Holes (PTH)

Metallized holes are divided into vias and pads. Vias are used for electrical connections between two layers of circuits, while pads are used for installing and inserting electronic components. Although vias and solder pads have different purposes, the formation of their holes is indeed the same. Through holes can be covered with solder mask on the surface to achieve insulation, or they can be immersed in solder during wave soldering to increase over current capacity, while solder pads can only be opened with solder mask.

Via in PAD

This design places the via in the middle of the SMT pad, fills the hole with resin during PCB production, and then electroplates the cap. The process is relatively complex, but the electrical performance is greatly improved, making BGA fan out more convenient.

Blind hole & Buried hole

These two types of holes do not penetrate the circuit board, but connect the inner and outer layers of the circuit board or the circuits between the inner layers in high-density circuit boards. Blind holes are precisely controlled by the Z-axis step during drilling after compression, to achieve the perfect depth of the hole; There is also a process of drilling holes first and then pressing them together. The processing of buried holes cannot be carried out after pressing, and it is necessary to drill and sink the core plate before pressing, and then drill and sink again after pressing.

Half hole

The half hole design is located at the edge of the circuit board, half inside the circuit board, half cut off with a milling cutter, and the remaining half of the metalized hole can be used as a board edge connector to splice with other circuit boards.