PCB circuit board three common holes in detail

First of all, let’s introduce the PCB in the common types of drilling data: through-hole, blind holes and buried holes. The meaning and characteristics of these three types of holes are carried out as described in the following questions.

Through-hole (VIA), which is a common hole conductive or connecting copper foil lines between the conductive pattern at different levels of the circuit board. Unlike blind or buried holes, through-holes cannot be inserted into copper-plated holes for component leads or other reinforcement materials.Double-sided PCB Since PCBs are made of multiple layers of copper foil, each of which is covered with an insulating layer, the layers of copper foil cannot communicate with each other. In order to connect signals, you need to use a through-hole (pass-through). For this reason, a through-hole is also known as a Chinese through-hole.

A through-hole is characterized by the fact that the through-hole of the circuit board must be plugged in order to meet the customer’s needs. The traditional aluminum hole plugging process has been changed, and white mesh is used to complete the solder resist and hole plugging of the circuit board board surface to achieve production stability and quality reliability. The main function of the through-hole is to realize the interconnection and conduction between circuits. With the rapid development of the electronics industry, the manufacturing process of printed circuit boards and surface mount technology has put forward higher requirements. Therefore, the blocking technology of the through-hole came into being, it needs to meet the following requirements:1. The through-hole must have copper, solder resist can be inserted or not; 2. The through-hole must have tin and lead, with a certain thickness requirement (4um), there can be no solder resist ink into the hole, so as not to cause the hole to hide the tin beads; 3. The through-hole must be plugged by the solder resist ink, opaque, can not be a tin ring, tin beads and the flatness requirements.

Blind vias are a method of connecting the PCB’s external circuitry to the adjacent inner layer through plated holes. It is called blind through because the opposite is not visible. At the same time, blind vias are used to improve the utilization of space between PCB layers. A blind vias is a through-hole that leads to the surface of a printed circuit board.

Blind vias are characterized by being located on the top and bottom surfaces of the board with a certain depth and are used to connect the surface circuits to the internal circuits below. The depth of the hole usually does not exceed a certain ratio (hole diameter). This manufacturing method requires special attention to the depth of the holes (Z-axis), as inattention can lead to difficulties in plating the holes, and is hardly used by manufacturers. Another method is to pre-drill holes in individual circuit layers for the circuit layers that need to be connected and then glue them together. However, this requires precise positioning and alignment devices.

Submerged holes are guide holes inside the PCB that carry the link between any of the circuit layers, but do not lead to the outer layer and do not extend across the board as well as to the surface.

Submerged holes are characterized by the fact that this process cannot be achieved by drilling in after bonding. Drilling operations must be implemented on individual circuit layers, first by partial bonding of the inner layer, then by plating, and finally by total bonding. Buried boreholes are time-consuming and expensive compared to the original through-hole and blind holes. This process is usually only used for high-density circuit boards to increase the available space in other circuit layers.

Drilling is a very important part of the PCB manufacturing process and should not be treated sloppily. Drilling is the process of drilling the required through holes in a copper-clad board to provide electrical connections and fixtures. If not done properly, the through-hole process will be faulty and the device will not be secured to the board. In light cases, the results of use will be affected, and in heavy cases, the entire board will be scrapped. Therefore, the drilling process is very important.

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