退火工艺对Au-20Sn钎料组织的影响

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

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。

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 intermetallie 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 E-phase（ containing Sn of 10% - 18.5% , mole fraction） and 8- 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 E-phase and 8-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 （＋ 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.