In the process of PCBA processing, reflow soldering is a very important process, which will be divided into three dimensions: basic concept, process flow and process characteristics. PCBA reflow soldering has good manufacturability, and there are no special requirements for the layout position, direction and spacing of components. The layout of components on reflow soldering interface mainly considers the requirements of solder paste printing steel mesh window on component spacing, inspection and repair space, and process reliability. However, many PCB boards explode, which is the most common quality reliability defect, and its causes are relatively complex and diverse. In the electronic product soldering process, the higher the soldering temperature, the greater the probability of board explosion.
1. insufficient curing of substrate
If the substrate is not cured enough, the heat resistance of the substrate will be reduced, and the copper-clad laminate will easily explode when the PCB is processed or subjected to thermal shock. The reasons for the insufficient curing of the substrate may be that the insulation temperature is low, the insulation time is insufficient, or the amount of curing agent is insufficient.
2. Improper choice of reflow temperature
According to the author’s understanding, improper reflow temperature will also lead to PCBA welding plate explosion. This is mainly because the temperature has certain inducement to the plate explosion, and the optimized reflow soldering temperature based on the comprehensive analysis of product characteristics also has certain effect on suppressing the plate explosion.
3. There are volatiles
The formation of volatiles is a necessary condition for PCBA welding to produce explosive plates. For example, moisture absorption, when water vapor evaporates and diffuses, the pressure will change with the temperature, and the existence of water vapor is one of the reasons for PCBA welding plate explosion. In addition, when moisture causes PCBA circuit board to be in a humid environment during storage and production, it will affect PCBA welding, and then lead to its board explosion. In addition, moisture in the storage environment will also cause changes in PP characteristics. Moreover, in the absence of protection, PP is extremely susceptible to moisture, so we must pay attention to moisture protection at ordinary times.
The above three reasons may lead to PCB board explosion in the welding process, which is helpful to everyone. However, in the welding process of electronic products, reducing board explosion is also a guarantee for quality, so as to have efficient work, ensure smooth SMT production, product quality and improve the qualified rate of enterprises.