The first step of PCB fabrication is to sort out and check the layout of pcb multilayer circuit board. The PCB manufacturing factory receives the CAD files from the PCB design company. Because each CAD software has its own unique file format, the Shenzhen PCB factory will convert it into a unified format Gerber. Then the engineers in the PCB factory will check whether the PCB layout conforms to the manufacturing process and whether there are any defects.

In the first phase of home made PCB information, the layout of PCB multilayer PCB is printed on paper with a laser printer, and then transferred to the copper clad plate. However, during the printing process, the printer is prone to ink shortage and breakpoint, so you need to manually use an oily pen to supplement ink.

A small amount of production is OK, but if this defect is transplanted to industrial production, it will greatly reduce the production efficiency. Therefore, PCB factories generally adopt the method of photocopying to print PCB layout onto film. If it is a PCB multilayer circuit board, the layout films printed from each layer will be arranged in order. The film is then punched with alignment holes. The alignment holes are very important. In order to align the manufacturing materials of each layer of PCB, the alignment holes should be used.

Fabrication of core plate

Clean the copper clad plate. If there is dust, the final circuit may be short circuited or open circuited.

The following figure is the legend of an 8-layer PCB, which is actually made up of 3 copper clad plates (core plates) and 2 copper films, and then bonded with semi cured sheets. The production sequence starts from the middle core boards (4 and 5 layers of lines), and then they are stacked together and fixed. All multilayer PCB boards are made similarly, except that only one core board and two copper films are used.