What are the reasons that affect the welding quality of PCB circuit boards?

by:A-TECH      2021-03-24
Welding is actually a chemical treatment process. The PCB circuit board has problems in the welding process, which will lead to welding defects and deterioration of welding quality, thereby affecting the qualification rate of the circuit board. So, what are the reasons that affect the welding quality of PCB circuit boards? 1. The design of PCB affects the quality of soldering. PCB size is too large, although soldering is easier to control, but the printed lines are longer, the impedance increases, the anti-noise ability is reduced, and the cost increases; Neighboring lines interfere with each other, etc. Therefore, the PCB board design must be optimized. 2. The solderability of the circuit board holes affects the quality of soldering. The so-called solderability refers to the property that the metal surface is wetted by molten solder, that is, a relatively uniform continuous smooth adhesion film is formed on the metal surface where the solder is located. The poor solderability of the circuit board holes will result in false soldering defects, which will affect the parameters of the components in the circuit, resulting in unstable conduction of the components and the inner line, causing the entire circuit to fail. 3. Soldering defects caused by warpage Warpage is often caused by the temperature imbalance of the upper and lower parts of the PCB. PCB and components warp during the welding process, and defects such as virtual welding and short circuit due to stress deformation. When the PCB warps, the components themselves may also warp, and the solder joints located in the center of the components are lifted away from the PCB, resulting in empty soldering. This situation often occurs when only flux is used and no solder paste is used to fill the gap. When using solder paste, due to deformation, the solder paste and the solder ball are connected together to form a short circuit defect. The above is the analysis of the reasons that affect the welding quality of PCB circuit boards. Have you mastered it?
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