PCB Via and Blind Via Alignment_Shenzhen Weienchen Technology Co., Ltd.

PCB Via and Blind Via Alignment

source:Industry News release time:2022-10-10 Article author:yu Popular:pcb

　　 PCB Via and Blind Via Alignment(图1)

　　The guide hole alignment method uses the "guide hole" on the PCB to identify the number of layers of the PCB. The principle is mainly because the circuit connection of the multilayer PCB adopts the via technology. If we want to see how many layers the PCB has, we can identify it by looking at the vias.

　　On a basic PCB (single-sided motherboard), the parts are all concentrated on one side and the wires are all concentrated on the other side.

　　If you want to use a multi-layer board, you need to punch holes on the board so that the component pins can pass through the board to the other side, so the guide holes will penetrate the PCB board, so we can see that the pins of the part are soldered on the other side of.

　　For example, if the board uses a 4-layer board, then it needs to be routed on the 1st and 4th layers (signal layer), and the other layers have other uses (ground layer and power layer). Put the signal layer on the power layer and the power layer. The purpose of the two sides of the ground plane is to prevent mutual interference and facilitate modification of the signal lines.

　　If some board card guide holes appear on the front of the PCB, but cannot be found on the back, the EDA365 electronic forum believes that it must be a 6/8-layer board. If the same guide holes can be found on both sides of the PCB board, it is naturally a 4-layer board.

　　However, many board card manufacturers currently use another routing method, which is to connect only some of the lines, and use buried and blind via technologies in the routing. Blind via is to connect several layers of internal PCB to the surface PCB without penetrating the entire circuit board.

　　Buried vias are only connected to the internal PCB, so they cannot be seen from the surface only. Since the blind hole does not need to run through the entire PCB, if it is six layers or more, look at the board against the light source, and the light will not pass through. Therefore, there is a very popular saying before: the four-layer and six-layer or more PCBs are judged by whether the vias leak light or not.

　　This method has its reasons, and there are also inappropriate places. The EDA365 electronic forum believes that this method can only be used as a reference method.

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