激光焊接印制电路互连焊锡空洞的形成及规律研究

Study on the formation and regularity of solder voids in printed circuit interconnection with laser welding

在微电子封装领域尤其是PCB(Printed Circuit Board)的电子互连中,激光钎焊以非接触、高灵活性和高加工精度等优点代替传统的波峰焊、回流焊等成为理想的焊接技术。但由于激光钎焊以及焊料的特殊性,尤其在印制电路板/线的互连过程中焊锡空洞的产生始终无法避免,从而影响焊点的质量可靠性及信号传输性能。文章以高频印制电路板的焊接为研究对象,利用多种表征手段分析空洞的形成机制,研究了焊料颗粒与溶剂、焊盘状态、助焊剂等因素对线路表面焊料空洞形成的影响,优选出无空洞化激光焊接的改善方法,通过提取空洞数据并结合HFSS仿真建立有无空洞的传输线模型比较了信号传输损耗的差异及其影响规律。

In the field of microelectronic packaging,especially in the electronic interconnection of PCB(Printed Circuit Board),laser brazing has become an ideal welding technology instead of traditional wave soldering and reflow soldering with the advantages of non-contact,high flexibility and high processing accuracy.However,due to the particularity of laser brazing and solder,especially in the soldering process of printed circuit boards/wires,the generation of solder voids cannot be avoided,which affects the quality,reliability and signal transmission performance of solder joints.This paper takes the welding of high-frequency printed circuit boards as the research object,and uses various characterization methods to analyze the formation mechanism of voids.In this paper,an improvement method of laser welding without voiding is proposed.The difference of signal transmission loss and its influence law are compared by extracting void data and combining with HFSS simulation to establish a transmission line model with or without voids.