1. Prevent or increase substrate warpage due to improper inventory methods

　　(1) Due to the moisture absorption of the copper clad laminate during the storage process, the warpage will be increased, and the moisture absorption area of the single-sided copper clad laminate is large. If the inventory environment humidity is high, the single-sided copper clad laminate will significantly increase the warpage. The moisture of the double-sided copper clad laminate can only penetrate from the end face of the product, the moisture absorption area is small, and the warpage change is slow. Therefore, for the CCL without moisture-proof packaging, pay attention to the warehouse conditions, minimize the humidity in the warehouse and avoid the bare copper clad laminate, so as to avoid the increased warpage of the copper clad laminate in storage.

　　(2) Improper placement of CCL will increase warpage. Such as vertical placement or heavy objects on the CCL, poor placement, etc., will increase the warpage and deformation of the CCL.

　　2. Avoid warping caused by improper circuit design or improper processing technology of printed circuit boards

　　For example, the conductive pattern of the PCB board is unbalanced or the lines on both sides of the PCB board are obviously asymmetrical, and there is a large area of copper on one side, which forms a large stress and warps the PCB board. During the PCB manufacturing process, the processing temperature is high or the heat is large. Impact, etc. will cause the PCB board to warp. For the impact caused by the improper inventory method of the cladding board, it is better for the PCB factory to solve it. It is enough to improve the storage environment and prevent vertical placement and avoid heavy pressure. For PCBs with a large area of copper in the circuit pattern, it is best to mesh the copper foil to reduce stress.

　　3. Eliminate substrate stress and reduce PCB board warpage during processing

　　Because in the process of PCB processing, the substrate is subjected to the action of heat many times and the action of various chemical substances. For example, after the substrate is etched, it needs to be washed with water, and it needs to be dried to be heated. When the pattern is electroplated, the electroplating is hot. After printing green oil and printing logo characters, it should be dried by heating or drying with UV light. Also big and so on. These processes may warp the PCB.

　　4. During wave soldering or dip soldering, the solder temperature is too high and the operation time is too long, which will also increase the warpage of the substrate. For the improvement of the wave soldering process, the electronic assembly factory needs to cooperate with

　　Since stress is the main cause of substrate warpage, if the copper clad laminate (also called h-board) is baked before it is put into use, many PCB manufacturers believe that this approach is beneficial to reducing the warpage of the PCB board. The function of the baking board is to fully relax the stress of the substrate, thus reducing the warpage and deformation of the substrate during the PCB manufacturing process.

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