无铅锡银密封焊试验及可靠性分析

Seal-weld Experiments and Analysis of SA Lead-free Solder Joint

采用Sn3.5Ag(221℃)Indium8.9 T3-83.5%的焊膏,首先做了焊料的可焊性试验,随后设计了围框的密封焊试验,工艺样件由Cu80W镀金底板和柯伐镀金围框组成,在270℃恒定温度下,焊接时间2 min。最后对焊接后的样件做了X-ray空洞率及焊接层面微观检测分析并测量了IMC厚度。研究结果表明:不仅Sn3.5Ag焊料的可焊性好,而且在镀金层上的致密性也好,在X光透射下柯伐镀金围框的空洞率低于5%,只是随时可能产生的小气孔会严重影响焊接的密封性。

Sn3.5Ag （221 ℃ ） Indium8.9 T3-83.5% soldering paste was employed to do the weld ability test at the first. Later, a smart plan was schemed for enclosure frame seal-welding experiments. The processing samples are made up of a Cu80W gold-plated substrate and two Kovar alloy enclosure frames with gold-plated. The welding temperature was set at 270 ℃ constantly and time was about 2 minutes. At last, the packaged samples were used for X-ray penellation rate inspection, welding layer rnicmanalysis and IMC thickness measurement. Results show that the spread-ability of Sn3.5Ag is good, the generated solder is actually compacted in the gold-plated inner layer and it also can be easily found that the Kovar alloy enclosure flame void ratio less than 5% based on the X-my test. However, the small voids that may be produced at any time will have a strong impact on seal-welding .