Reasons and Solutions for Repair Welding Porosity in SMT Patch Processing

SMT patch processing is a complex process, and some small problems will inevitably occur during the operation. For example, if the soldering of the SMT patch has porosity, it will destroy the mechanical properties of its welded joints. Proper handling will not affect the overall quality of SMT.

SMT chip processing advantages: high assembly density, small size, and lightweight electronic products. The volume and weight of chip components are only about 1/10 of that of traditional plug-in components. Generally, after SMT is adopted, the volume of electronic products is reduced by 40%~60%, The weight is reduced by 60%~80%. 　　

High reliability and strong anti-vibration ability. The solder joint defect rate is low. Good high-frequency characteristics. Reduce electromagnetic and radio frequency interference. It is easy to realize automation and improve production efficiency. Reduce costs by 30%~50%. Save materials, energy, equipment, manpower, time, etc.

Disadvantages of SMT chip processing: the earlier the solder paste is combined, the more pores are formed. In the solidification process, there are also solder shrinkage, soldering, plated through holes, layered exhaust, entrained flux, etc., which are also causes of porosity. 　　

The reason for the porosity in SMT repair welding: During the welding process, the mechanical system of the porosity is more complicated. Normally, the porosity is caused by flux discharge from the solder in the sandwich structure during the reflow (2, 13) process.

The formation of pores is mainly determined by the solderability of the metalized area and changes with the decrease of flux activity, the increase of powder metal load, and the increase of lead weld coverage. Reducing the size of the solder particles will only increase the porosity. In addition, the formation of pores is also related to the time distribution between the agglomeration of the solder powder and the elimination of the fixed metal oxide.

Methods to control the formation of pores in SMT patches: 　　

1. Use a flux with higher activity; 　　

2. Improve the solderability of components or circuit boards; 　　

3. Reduce the formation of solder powder oxides;

4. SMT chip processing manufacturers are precisely due to the complexity of the process flow of SMT chip processing, so many SMT chip processing factories have appeared, and the processing of SMT chips has benefited from the vigorous development of the electronics industry. Film processing has contributed to the prosperity of the industry. Inert heating atmosphere; reduce the preheating degree of reflow lead.