印刷电路板组件表面阻焊膜发白的影响因素及原因分析

Factors affecting the whitening of solder mask on PCBA and cause analysis

研究了印刷电路板组件(PCBA)经波峰焊和清洗后,表面阻焊膜发白的影响因素,并通过实验探究其形成原因。结果表明,阻焊膜的油墨类型和厚度对PCBA表面发白有显著影响。该现象可归因于高温焊接时助焊剂在阻焊膜中的残留,这与阻焊膜本身所带孔隙及高温焊接过程中填料颗粒与树脂基体间形成的孔隙有关。改用深色油墨和减小阻焊膜厚度,发白问题得以解决。

The factors affecting the whitening of solder mask on the surface of printed circuit board assembly(PCBA)after wave soldering and cleaning were studied,and the causes of this phenomenon were analyzed experimentally in the laboratory.The results showed that the ink used to form the solder mask and its thickness had a significant effect on the whitening of PCBA,which could be attributed to the residue of flux in the pores existing in the solder mask itself and being formed between the filler particles and resin matrix during wave soldering at high temperature.This problem can be eliminated by using some dark solder mask inks instead of light ones and decreasing the thickness of solder mask.