After years of experience summary and scientific research verification of SMT processing plant, there is no evidence that the cavity in a single solder joint will cause the failure of the solder joint. However, in many cases, the cavity in the cross section of the pad is a huge quality hidden danger. Its quality has a much greater impact on reliability, and eventually leads to the cracking of the weld and failure.

Then, in the process of circuit board manufacturing, corresponding optimization and improvement should be carried out according to the customer's product and process requirements. The most important thing is to avoid cavities at the main weld positions through solder paste and reflow temperature control, and the size and quantity of cavities should also be controlled accordingly.

For core devices such as QFN, the packaging is unique and the process is difficult. The side of the welding end is exposed and there is no weldable coating. Generally speaking, the weldability of the left and right sides of the welding end is very poor in SMT processing, which is prone to poor wetting, bridging and voids. In this case, it is mainly because the thin solder paste is more likely to form a larger cavity. The main reason is that the thickness gap of the weld is too small, which makes it more difficult for the volatiles of the welding machine to be discharged through this "channel", resulting in the problem of "cavity".