If you have the opportunity to pick up a printed circuit board and observe it alittle, you willfind that there are many large and small holes on the circuit board. Take it up and look at the lamp on the ceiling, and you will find many densely packed small holes. The holes are not placed in a good

place, each hole is designed with a purpose. Commonly drilled holes in our printed circuit board(PCB) include via holes, blind holes, and buried holes, all of which function as circuit conduction. So, do you know the meaning of the three types of vias, blind holes, and buried holes drilled in printed circuit boards?

Conducting hole: Plating Through Hole, referred to as PTH, is a common hole used to conduct or connect copper foil lines between conductive patterns in different layers of the circuit board. It cannot be inserted into component leads or other Copper plated holes for reinforcement material.

You just need to pick up the PCB circuit board and face it to the light. The hole that can see the light is a through hole. This is also the simplest type of hole, because you only need to use a drill or laser to directly drill the entire circuit board. Yes, the cost is relatively cheap. Because the PCB is formed by stacking and accumulating many copper foil layers, an insulating layer is laid between each layer of copper foil, so that the copper foil layers cannot communicate with each other, and the signal connection depends on via holes. connect.

Blind hole: Blind Via Hole, which connects the outermost circuit of the PcB to the adjacent inner Layer with a plated hole. Because the opposite side cannot be seen, it is called a blind pass. In order to increase the space utilization of the PCB circuit layer, the blind hole process came into being.

This production method needs to pay special attention to the depth of the drilling hole (Z axis) to be just right. However, this method often causes difficulties in electroplating in the hole, so almost no manufacturers use it; it is also possible to place the circuit layers that need to be connected in advance on individual circuit layers. At the time, the holes are drilled first, and then glued together, but more precise positioning and alignment devices are required.

Buried hole: Buried hole is the link between any circuit layer inside the PcB but not connected to t

he outer layer, and it also means a via hole that does not extend to the surface of the circuit board. The connection of any circuit layer inside the PCB is not connected to the outer layer. This process cannot be achieved by drilling after bonding. Driling must be performed on individual circuit layers. First, the inner layer is partially bonded and then electroplated before being fully bonded.

Compared with the original through hole and blind hole It takes more work, so the price is also the most expensive. This process is usually only used in high-density HDI circuit boards to increase the available space for other circuit layers.