熔体过热对Sn-Cu焊料合金凝固组织及焊接性能的影响

Influence of melt overheating on solidification and welding properties of SnCu solder alloy

以Sn-5Wt%Cu无铅焊料合金为研究对象,探索了熔体过热对合金熔体结构、凝固组织和焊接性能的影响.运用四探针电阻法发现合金熔体过热至758℃附近后发生了明显的不可逆结构突变;熔体过热处理后的金相组织观察表明,该不可逆结构转变使合金凝固组织明显细化和弥散化、合金焊接接头的界面化合物层变得更薄、且界面粗糙度也得到了一定的改善.在260℃左右的铜基板铺展实验中,焊料合金的铺展面积增大了5%,润湿角减小了13%,其润湿性有较大提高.

This paper explored the influence of melt overheating on the melt structure,solidification and weldability by researching the Sn-5Wt% Cu lead-free alloy.It revealed that when the tempreture of melt reaches 785℃,these is an obvious irreversible change to the structure by the four-probe resistivity methed.The result by obsearving the melt overheating microstructure shows that the irreversible change make the alloy solidification thinner and more diffusive,the alloy welding joint interface layer thinner.At the same time,there is also some improvement on the interface roughness.When the tempreture reaches 260℃ under the examination of copper baseplate spreading,the spreading area of the solder alloy increased by 5% the wetting angle decreased by 3% and the wettability improved greatly.