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Several common problems of solder paste in PCBA applications

177 Published by FASTPCBA 1月 13,2021

Solder paste is one of the commonly used materials in our SMT patch. There are also some distinctions in the PCB Assembly Manufacturer. Some customers will choose halogen-containing solder paste and some will use halogen-free solder paste. The electronic PCBA processed products produced will naturally be different, in order to ensure the circuit The quality of PCBA processing, today FASTPCBA will discuss several common problems in solder paste application in PCBA.

1. The agglomeration of solder paste occurs when printing pcb board, which is mainly seen in the printing process of the sealed print head. Because the solder paste and solder powder are rubbed by the surroundings, the oxide on the surface of the solder powder is easily removed, and the solder paste is getting dry. Caused. For solder paste, we hope that the performance can be kept stable during the printing operation cycle, and the flux and solder powder will not react.

2. Solder spatter is mainly caused by the relatively low boiling point of the solvent in the solder paste.

3. For LGA soldering, halogen-free solder paste can be used (the activity is relatively low, and the wet residue can also meet the requirements of SIR), but the soldering defects such as ball sockets are relatively high; the halogen-containing solder paste is relatively strong , The welding yield is relatively high, but there may be a risk of leakage.

4. Water-soluble solder paste/flux. The design of water-soluble solder paste is to use deionized water for cleaning without using VOC organic solvents. The formula of the water-soluble flux is designed according to the cleaning process, and the activator is added, so it must be cleaned after use. Generally, no-clean solder paste does not use water-soluble design, because it is meaningless and has certain human hazards. Can be washed with water, it must absorb moisture, and moisture absorption will reduce the insulation resistance.

5. Three-proof coating of no-clean solder paste. Some products require high reliability and require three-proof coating. The question is, at present, most products use no-clean solder paste, so do I need to clean it during the three-proof coating? What are the risks of not cleaning? This is an issue that has been controversial in the industry.

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