退火工艺对Au-20Sn钎料组织的影响

采用叠轧-合金化法制备Au-20Sn钎料,研究合金化退火工艺对Au-20Sn钎料显微组织的影响。结果表明:Au/Sn界面在叠轧过程中形成AuSn4,AuSn2和AuSn三个金属间化合物(IMC)层。在200℃退火时,IMC层的厚度随退火时间的延长而逐渐增大。当退火时间延长至48 h时,IMC层发生转变,Au-20Sn钎料最终形成由ζ相(含Sn 10%～18.5%,原子分数)和δ(AuSn)相组成的均质合金。在250℃退火时,Au/Sn界面扩散速度增大,退火6 h后Au-20Sn钎料组织完全转变成ζ相+δ(AuSn)相。在270℃退火时,IMC层熔化,反应界面转变成为固-液界面,Au-20Sn钎料组织转变为脆性的(ζ’+δ)共晶组织。综合Au-20Sn钎料的性能和生产要求,得到优先退火工艺为250℃退火6 h。

Effects of annealing process on microstructure of Au-20Sn solder

AuSn solder was prepared by rolling-annealing process.The effects of annealing process on microstructure of the Au-20Sn solder were investigated.The results show that three intermetallic compound(IMC) layers of AuSn4,AuSn2 and AuSn are formed at the Au/Sn interface during rolling process.When annealing at 200 ℃,the IMC layers grow gradually with increase of annealing time.After annealing at 200 ℃ for 48 h,the IMC layers are fully transformed into ζ-phase(containing Sn of 10%~18.5%,mole fraction)and δ-phase(AuSn),forming a homogeneous and stable Au-20Sn solder.When annealing at 250 ℃,the IMC layers grow much faster than that at 200 ℃.The IMC layers are fully transformed into ζ-phase and δ-phase after annealing for 6 h.When Au-20Sn solder is annealled at 270 ℃,the IMC layers is molten and the Au/Sn interface becomes solid-liquid state,and brittle(ζ’+δ) eutectic microstructure forms in the Au-20Sn solder.The optimal annealing technology of the Au-20Sn solder is annealing at 250 ℃ for 6 h to obtain the best properties for application in engineering.