超声引线键合点形态及界面金属学特征

Study on the Configuration and the Interfacial Metallurgic Characteristics of Ultrasonic Wire Bonds

采用超声键合的方法,研究了键合点的形成原因,通过SEM及EDX分析发现超声键合过程中存在扩散现象。对键合点进行了老化试验,考察了键合点上25μm直径的质量分数为A l+1%Si引线的组织演变情况,在170℃下,随着老化时间的延长,键合点上引线内部形成了大量的微裂纹和孔洞,连接成线,与超声振动方向平行,分析了产生原因以及对键合点可靠性的影响。

At room temperature,the Al ＋ 1% Si wire of 25 μm diameter was bonded to the Au/Ni/ Cu pad successfully by ultrasonic bonding method. We investigated the interfacial metallurgical characteristics between the wire and pad by Scanning Electron Microscopy （SEM） and Energy Dispersive X -ray Spectrometer （EDX）. It is found that there is visible interdiffusion between element Al in the wire and element Ni in the pad. It is probably that both plastic flow under the pressure of the wedge and wire softening by the ultrasonic vibration enhance the diffusion. After aged at 170℃ ,there are many vacancies and micro -cracks in the bond wire. The reason and their effects on reliability are concerned.