倒装芯片组装中微米级互连焊点的界面金属间化合物生长及动力学

Interfacial intermetallic compound growth and kinetic in the micro-solder joint of flip chip assembly

利用焊点间距为100μm,高度约为45μm,成分为Sn-3.0Ag-0.5Cu(wt%)(SAC305)的倒装硅芯片与BT树脂基板组装互连,分别在150、125和100℃条件下时效至650 h。研究时效过程中界面主要金属间化合物的生长,结合经验功率定律及阿伦斯公式计算基板侧Cu焊盘界面IMC生长的动力学参数,对IMC的生长动力学探讨。结果表明,在互连回流后,双侧焊盘界面主要IMC为(Cu,Ni)6Sn5。在时效前100 h,(Cu,Ni)6Sn5生长速率较快;而在随后的时效过程中,随时效时间的增加生长速率逐渐降低。界面主要金属间化合物(Cu,Ni)6Sn5生长动力学研究结果可知:150、125以及100℃条件下时间参数分别为2.61、2.35和2.18,界面(Cu,Ni)6Sn5的生长激活能为67.89 kJ/mol。

The flip chip with Sn-3.0Ag-0.5Cu （wt%） solder joints were assembled onto BT substrate, and solder joint had stand-off height of approximately 45 p^m and pitch of 100 μm. After assembly, the flip-chip assemblies were isothermally aged at 150, 125 and 100 C for up to 650 h. This work studies intermetallic growth and kinetics in solder joints on Cu pad surface by empirical power law and Arrhenius equation through thermal aging. The results show that, after the reflow of flip chip, the （Cu,Ni）6Sn5 forms as the dominant interfacial IMC on Ihe both pad interfaces. During thermal aging, before 100 h, the growth rate of （Cu, Ni）6Sn5 is quicker, while after 100 h, the growth rate becomes slower and slower. The result of the calculated kinetic parameter shows the time exponents are 2.61, 2.35 and 2.18 at 150, 125 and 100 C respectively, and the activation energy of （Cu, Ni）6Sn5 growth is 67.89 kJ/mol.