微焊点中金属间化合物形成机理研究

Research of intermetallic compounds formation mechanism in micro solder joint

研究了Sn36Pb62Ag2焊料焊接铜质微型器件的焊点微观组织,在焊料与元件结合界面处形成了Cu_6Sn_5结合层,结合层平均厚度为1.1μm。同时试验研究了在两种不同热考核试验条件下微型元件中微焊点的微观组织变化,结果表明,在100℃热考核试验样件下,试验时间1 000 h,样件界面处Cu_6Sn_5层厚度增加,平均厚度为5.8μm;而在125℃热考核试验条件下,仅用168 h,样件界面处Cu_6Sn_5层厚度就发生急剧变化,增加到10μm以上,并且出现Cu3Sn层。试验中还发现,热考核试验会使焊料层中出现铅板块,温度越高铅板块相对面积越大,这对元件剪切强度产生了巨大影响,随着热考核温度的升高,剪切强度逐渐降低。

Microstructures of micro solder joints which were formed between Sn36Pb62Ag2 and micro-elements were studied. The intermetallic compound Cu6Sn5 was formed in the interface between solder and micro-element. The average thickness of CueSfl5 was 1.1 pm. The experiments also studied the microstructures＇ developments of micro solder joints of micro-elements in two different temperatures. When the specimen was heat in 100 ℃ with 1 000 hours, the thickness of Cu6Sn5 increased to 5.8 μm. The Cu6Sn5 thickness of the other specimen increased to 10 μm quickly with the experiment＇s condition 125 ℃, 125 hours. At the same time, it was found that there was Cu3Sn in the interface. In the experiments it was found that Pb agglomerations were formed in the solder. And the area of Pb agglomeration increased with the temperature. The shear strength of elements was affected by this phenomenon effectively. The shear strength decreased with the increasing experiment temperature.