Sn-18Bi-XCu低温无铅钎料微观组织及力学性能

Microstructure and mechanical properties of Sn-18Bi-XCu low-temperature lead-free solder

Sn-Bi系钎料作为一种低熔点钎料在低温封装领域有着广阔的应用前景.但是Bi性质脆弱,使得Sn-Bi系钎料表现出脆性大,塑性差的特点,影响焊接接头性能.文中采用合金化的方法,通过在Sn-18Bi钎料中添加第三组元Cu制备新型的Sn-18Bi-XCu低温无铅钎料,并对其微观组织及力学性能进行分析.结果表明:当Cu质量分数约为0.5%时可以使脆硬相Bi细小分散,避免形成粗大的富Bi带,缩小合金的熔化温度范围,使钎料获得最佳的组织和力学性能.这主要是由于在钎料基体中原位生成细小弥散的棒状或杆状的Cu-Sn金属间化合物的钉扎强化作用.

As a low melting point solder at low temperatures in the packaging field,Sn-Bi solder has broad application prospects.Due to the fragile nature of Bi,Sn-Bi solder exhibits brittle,poor ductility characteristics,and affects the performance of welded joints.A new type of low-temperature solder,Sn-18Bi-XCu was fabricated by adding Cu component into the tin-bismuth series solder.The microstructure and mechanical properties of lead-free solders were studied.The results show that when the Cu content is about 0.5%,bismuth in brittle phase was fined and deconcentrated,avoiding the formation of coarse Bi-rich zone and shortening the alloy melting temperature range.Finally,we obtained the best solder microstructure and mechanical properties,because the addition of Cu element can refine the microstructure of the Sn-Bi-Cu solder by forming appropriate rod-like shape fine IMC