1. mechanical drilling: the use of drilling machines drill holes, our smallest hole diameter can be up to 0.15mm. generally most of the through holes seen are made using mechanical drilling.
2. Laser drilling: The holes made by using laser light on the PCB board, the hole diameter is about 0.076~0.1mm. HDI board will use a lot of laser drilling to achieve the blind/buried hole requirement.
3. Through hole: divided into PTH (Plating Through Hole) & NPTH (Non Plating Through Hole) 6.
4. As the name implies, it is a hole from the front side to the back side of the PCB, using the drill bit to drill through all layers from top to bottom. 7.
NPTH holes are usually used for fixing the PIN pins of the parts or for fixing the PCB to the mechanism enclosure, without the need of conduction.
5. Blind/Buried via: Blind via, one side of the PCB on the outside, the other side of the inner layer, because the appearance of only one side of the hole, so called blind. Buried via is a hole buried between the inner layers of the PCB, and the location of the hole cannot be seen from the outside. 10.
Both blind and buried holes are holes that do not need to be penetrated. Because of the increasing miniaturization of products, the available space on the PCB is getting smaller and smaller, if all the holes are made through, they will occupy too much area and cannot be effectively streamlined. Therefore, through the blind and buried hole technology, to improve the utilization of PCB area, and achieve the goal of product miniaturization.
6. Blind and buried holes are designed with a diameter of about 4~6 mil (0.1~0.15mm), and they are used to guide through various pathways. Generally speaking, the buried holes are drilled mechanically to make 6mil (0.15mm), while the blind holes are drilled by laser to make 4mil (0.1mm).
7. PTH half holes.
8. also known as blue bud hole (castellation), in the PCB side panel side of the designated area coated with copper, the place is straight, curved or SLOT groove, can be coated with a layer of copper in the board wall there, for subsequent product assembly
9. Tapered hole / Countersink hole: The hole for screw fixing when the PCB is assembled with the mechanism afterwards, according to the shape of the groove can be divided into Tapered hole (Countersink) & Countersink hole (Counterbore). Tapered holes are always available at 82 degrees / 90 degrees / 100 degrees. 16.
10. Legend - Tapered hole Countersink
11. Legend - Countersunk hole