微电子封装中全Cu_(3)Sn焊点高温服役下的微观组织演变

Microstructure Evolution of Full-Cu_(3)Sn Solder Joints in Microelectronic Packaging Under High-Temperature Service

通过过渡液相(TLP)连接工艺在320℃下保温24 h直接制备全Cu_(3)Sn金属间化合物(IMC)微焊点,并在570℃下进行高温老化。通过扫描电子显微镜(SEM)、能谱仪(EDS)以及电子背散射衍射仪(EBSD)对全Cu_(3)Sn微焊点高温老化过程中相演变规律和形貌变化进行了表征,在此基础上探究了IMC生长的动力学以及界面空洞萌生的机理。结果表明:全Cu_(3)Sn微焊点中的Cu_(3)Sn层首先会全部转变为Cu_(41)Sn_(11),随后会生成一种由Cu_(41)Sn_(11)晶粒和弥散的α(Cu)颗粒组成的双相组织,并最终转变为均匀的α(Cu)固溶体。其次,空洞的萌生和长大发生在双相组织向α(Cu)固溶体转变过程中的焊点中心处,最终在焊点中心处产生大量连续空洞。通过对α(Cu)层进行生长动力学计算得知,在整个时效过程中,体扩散为主要扩散方式,α(Cu)激活能为11.28 kJ/mol。该研究结果对全Cu_(3)Sn IMC微焊点的高温服役有一定的参考意义。

Full-Cu_(3)Sn intermetallic compound(IMC)micro solder joints were prepared by transient liquid phase(TLP)joining technique at 320℃for 24 h.The high-temperature aging treatment of the micro solder joints was carried out at 570℃.The phase evolution and morphology change of full-Cu_(3)Sn micro solder joints during high-temperature aging were characterized by the scanning electron microscope(SEM),energy disperse spectroscope(EDS)and electron backscatter diffraction(EBSD).On this basis,the kinetics of IMC growth and the nucleation mechanism of interfacial cavities were investigated.The results show that the Cu_(3)Sn layer in full-Cu_(3)Sn mi-cro solder joints is firstly transformed into Cu_(41)Sn_(11),and then a two-phase microstructure consisting of Cu_(41)Sn_(11) grains and dispersedα(Cu)particles is generated,and it finally transforms into a homogeneousα(Cu)solid solution.Secondly,the nucleation and growth of the cavities occur at the center of solder joints during the transformation of the two-phase microstructure toα(Cu)solid solution.Finally,a large number of continuous pores are produced at the center of solder joints.The growth kinetics of theα(Cu)layer was calculated.The result shows that the bulk diffusion is the main diffusion mode in the whole aging process,theα(Cu)activation energy is 11.28 kJ/mol.The results of the study have certain reference significance for the high-temperature service of full-Cu3Sn IMC mirco solder joints.