What are the common PCB through-hole processing methods?

　　In the PCB manufacturing process, vias are important bridges that connect signals or power between different circuit layers. In order to meet the requirements of electrical performance, solderability, reliability, and manufacturing processes in different application scenarios, vias often require special treatment in PCB production. This article will introduce three common methods of through-hole treatment: through-hole opening, through-hole plug oil, and through-hole cover oil.

　　To understand the through-hole processing method, it is necessary to first understand what a through-hole is. A through-hole refers to a metal hole on a PCB board used to connect different layers of circuits. The English name is via, which is mainly used to achieve electrical connections between different layers of the PCB. In addition, it also has a heat dissipation function. There are three types of vias: through holes, blind holes, and buried holes. When it comes to via treatment, it generally refers to through holes because blind holes and buried holes usually do not require special treatment, especially buried holes.

　　In addition, we need to know that in the production of PCBs, a solder mask layer is required, and via processing is closely related to the solder mask layer, because via processing is mainly carried out on the solder mask layer. After understanding these, it will be easier to understand the via processing method.

　　Through hole opening: Through hole opening refers to leaving a window on the solder mask layer for the through-hole, completely opening it to the outside without covering or plugging oil. Its main function is to dissipate heat and facilitate electrical contact or serve as a testing point.

　　Through hole plug oil: Through hole plug oil refers to the use of special ink or resin to completely fill the inside of the through hole, which can be further flattened or electroplated. Its main function is to enhance the mechanical strength and sealing of the hole, to prevent solder from penetrating into the hole.

　　Through hole cover oil: Through hole cover oil refers to covering the surface of the through hole with solder mask ink, but not filling the inside of the hole. It only "covers" the hole through the solder mask layer, so that the hole is not exposed. Its main function is to prevent impurities, solder or flux from entering the hole and protect the through hole from contamination.