4.1 Design capability of thick copper PCB products:
There are mature manufacturing processes and methods of thick copper PCB in domestic large-scale PCB manufacturers, and our company has also improved the thick copper products one after another, but there are still many shortcomings. Combining with the development trends of the industry and our manufacturing process of thick copper PCB, we independently developed a complete set of control and control design schemes about the lamination and folding of thick copper PCB, compensation between lines and glue filling between super thick copper PCB.

4.2 Materials and key equipment for key processes of thick copper PCB products

4.2.1 Selection of materials
① Plate selection: Thick copper plates have very high requirements for plates. Our company uses all domestic and foreign high TG plates and high frequency products when making thick copper plates;
② Thick copper PCB drilling technology:
The drilling of thick copper PCB is a major difficulty in drilling technology. The thicker the copper, the greater the loss of the drill bit. When our company produces thick copper PCB, a special UC thick copper drill bit is used as the drill tool. Combined with the drilling parameters of thick copper PCB, the produced hole wall is flat and smooth, and no phenomenon of hole wall cracking or rough hole wall is found.
③ Selection of etching solution: Etching is the key technology of circuit manufacturing and imaging. With the increase of copper thickness, the etching difficulty increases, and the quality of the circuit is difficult to control.
④ Solder resistance printing: Thick copper screen printing mainly considers the binding force between soldermask and base material. The thicker the copper, the more soldermask is needed to fill between lines, and the more bubbles will be generated. To solve this problem, our company purchased a solder resistance vacuum pump to solve the quality abnormality of soldermask bubbles in thick copper PCB, and the edge of the produced product line is flat without bubbles.
⑤ Selection of gong knives: All thick copper PCB are made of high TG materials, and the higher the TG value, the strict requirements for the selection of knives. For thick copper products, our company specially ordered a titanium-plated gong knife to produce thick copper plates, so as to ensure the smooth edges of the produced plates;

Thick copper PCB products are all used for high-current and high-power products, so the process quality control must be strictly controlled. The R&D department identified the process difficulties and key control points of thick copper PCB products according to the product characteristics of thick copper PCB, and formulated the Design and Operation Guidelines for Thick Copper PCB and the Process Failure Mode Control for Thick Copper PCB, which effectively controlled the product design, process control and finished product performance test to ensure that thick copper PCB products meet customer requirements. According to this design requirement and process quality control, the quality of thick copper PCB produced by our company has reached a stable state at present, and obtained the following results.