Electrical principles and mechanical structure design determine the size and structural shape of the PCB based on the overall structure of the machine. Draw an SMT printed circuit board outline process diagram, indicating the length, width, and thickness of the PCB, the position and size of structural components and assembly holes, leaving edge dimensions, etc., so that circuit designers can conduct wiring design within an effective range. The choice of assembly form depends on the type of components in the circuit, the size of the circuit board, and the equipment conditions of the production line. The principle for selecting the assembly form of printed circuit boards is to follow the principles of optimizing processes, reducing costs, and improving product quality. Firstly, the overall goals of electronic product functions, performance indicators, costs, and overall dimensions of the machine should be determined. When developing and designing new products, the performance, quality, and cost of the product should be positioned first.

In general, any product design needs to balance and compromise between performance, manufacturability, and cost, so the first step in design is to give the product its purpose and grade positioning.