PCB warpage cause is that the substrate used may be warped on the one hand. And on the other hand, the warpage is caused by thermal stress, chemical factors and improper process in the manufacturing process of the PCB board. So, what are the preventive measures for warpage of the PCB board printer?
1. Prevent substrate warping caused by improper inventory method
(1) During the storage of the copper clad laminate, if the humidity of the inventory environment is high, the copper clad laminate will increase warpage due to moisture absorption. Therefore, it is necessary to pay attention to the warehouse conditions for the CCL without moisture-proof packaging, and try to reduce the humidity in the warehouse and avoid the bare CCL.
(2) Improper placement of copper clad laminates will increase warpage. Such as vertical placement or heavy objects on the copper clad laminate will increase the warping deformation.
Solution: Improve the storage environment and avoid vertical placement and avoid heavy pressure.
2. Avoid warping caused by improper circuit design or improper processing technology
For example, the conductive circuit pattern of the circuit board is unbalanced or the two sides of the circuit are obviously asymmetrical, which will form a large stress and cause warpage; in the PCB board manufacturing process, the temperature is too high or the large thermal shock causes warpage.
Solution: For circuit boards 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 board warpage during processing
Because in the PCB board making process, the substrate has to be subjected to heat and many chemical substances. For example, after the substrate is etched, it needs to be washed with water, dried and heated, and the thermal shock experienced by the hot air spraying tin is large. These processes may cause the PCB board to warp.
Solution: Since stress is the main cause of substrate warpage, if the copper clad laminate is baked before the copper clad laminate is put into use, the role of the bake plate is to fully relax the stress of the substrate and help reduce the warpage of the substrate in the PBC making process.
4. When wave soldering or dip soldering, the solder temperature is too high and the operation time is too long, which will increase the warpage of the substrate
Solution: To improve the wave soldering process, the electronic assembly factory needs to cooperate.