Let’s first introduce the common drilling holes in PCB: through hole, blind hole and buried hole. The meaning and characteristics of these three kinds of holes.

Through hole (VIA), a common hole used to conduct or connect copper foil lines between conductive patterns in different layers of a circuit board. Such as (e.g., blind hole, buried hole), but can not be inserted component lead leg or other reinforcement material copper plated hole. Because PCB is formed by many copper foil layers stacked and accumulated, each layer of copper foil will be covered with an insulating layer, so that the copper foil layers cannot communicate with each other, and the link of its signal is through hole (via), so it has the title of Chinese through hole.

Characteristics: in order to meet the needs of customers, the circuit board must be through the hole hole, so that in the change of the traditional aluminum sheet plug hole process, complete the circuit board board soldering and plug hole with white mesh, so that its production is stable, reliable quality, more perfect use. With the rapid development of the electronic industry, it also puts forward higher requirements for the technology of printed circuit board production and surface mount technology. The process of conducting the plug hole through hole is applied, and the following requirements should be met:

1. The copper in the guide hole is ok, but the soldering plug is optional.

2. There must be tin and lead in the guide hole, and there must be a certain thickness requirement (4um), and there must be no soldering ink into the hole, so there are tin beads in the hole.

3. The pass-through hole must have soldering ink plug hole, no light transmission, no tin ring, tin beads and other requirements of leveling.

Blind hole: it is to connect the outermost circuit in PCB with the adjacent inner layer by electroplating hole, because the opposite cannot be seen, so it is called blind pass. At the same time, in order to increase the space utilization between PCB circuit layers, blind hole is applied. That is, to a surface of the printed circuit board through the hole.

Features: the blind hole is located on the top and bottom surface of the circuit board, with a certain depth, used for connecting the surface circuit and the inner circuit below, the depth of the hole usually does not exceed a certain ratio (aperture). This way of production will need to pay special attention to the depth of the hole (the Z axis) to the right, do not pay attention to words will cause difficult hole plating so almost no factory used, can also be connected in advance to the layer in the individual circuit when the circuit was first drill hole, and then sticking together, but need more precision positioning and contrapuntal device. Embedded hole refers to the connection between any circuit layers within the PCB without conducting to the outer layer, and also refers to the conducting hole that does not extend to the circuit board surface.

Features: in this process, it is impossible to use the method of bonding and then drilling. The drilling must be carried out at the time of individual circuit layers, and the inner layer should be partially bonded before electroplating, and then all of them can be bonded. It takes more time than the original through hole and blind hole, so the price is also the most expensive. This process is usually only used for high-density circuit boards to increase the usable space of other circuit layers.

Drilling is very important in PCB production process. Because drilling is to drill the required hole in the copper clad plate, in order to provide electrical connection, fixed device function. If the operation is improper, there is a problem in the process of drilling, the device cannot be fixed on the circuit board, which will affect the use of the light, or the whole board will be scrapped, so the drilling process is very important.