【摘要】 针对SAC305和改良添加了Ni、Sb、Bi元素的2种焊料及其分别与NiSn、NiAu、NiPdAu 3种镀层器件钎焊形成的互连焊点,采用SEM、EDS、EPMA、TEM、DSC等方法研究了Ni、Au、Pd、Sb、Bi等添加元素对金属间化合物(IMC)种类及厚度、焊料第二相形貌及分布以及焊点剪切强度的影响。结果发现,受Ni元素界面耦合作用的影响,焊点器件侧和印刷电路板(PCB)侧生成的IMC均为(Cu, Ni)6Sn5化合物;焊料中Sb、Ni元素减缓IMC生长,因此同一镀层下改良焊料的界面IMC厚度小于SAC305的;镀层中Au元素降低IMC生长速率,而Pd元素促进IMC生长,因此同一焊料下NiPdAu镀层样品的界面IMC厚度最大,而NiAu镀层样品的界面IMC厚度最小;镀层中Au、Pd元素的加入,促进焊料中Ag3Sn相从弥散颗粒状分布转为网状分布,焊点强度得到提升;焊料中Ag、Cu元素的加入,增加弥散分布的(Cu, Ni)6Sn5和Ag3Sn体积分数,提高焊点剪切强度;焊料中添加Bi元素导致焊料熔点降低,但可析出Bi单质起到弥散强化作用;因此,添加了Ni、Sb、Bi元素的改良焊料的焊点剪切强度,均高于同等条件下SAC305焊点样品的剪切强度。更多还原

【Abstract】 The eutectic Sn-Ag-Cu(SAC) alloy is the most widely used solder alloy in consuming electronic devices owing to its good wettability and mechanical properties. However, the growth of automotive electronics working at a higher temperature than consuming electronics, requires more reliable solder alloy during microelectronic packaging, which can be achieved by elemental alloying. In this work,the modified Sn-Ag-Cu alloy with Ni, Sb and Bi addition was soldered on the surface of NiSn, NiAu andNi Pd Au coating layer respectively, and the effects of elemental addition on the interfacial microstructure and shear strength were investigated systematically. It was found that compared to the commercial SAC305 solder joint, the modified Sn-Ag-Cu solder joint has a thinner interfacial IMC layer while a higher shear strength under the same reflowing conditions, although the formed IMC species are all(Cu, Ni)6 Sn5 at both the chip side and the printed circuit board(PCB) sides. The addition of Ni, Sb and Au elements can reduce the IMC growth rate, while the addition of Pd increases the IMC growth. For the same solder alloy and reflowing process, the thickness of IMC layer on Ni Pd Au is the largest, while that on Ni Au coating layer is the smallest. Au or Pd addition in the coating layer affects the distribution of Ag3 Sn from dispersive particles to net-like morphology, resulting in an improvement of solder shear strength. The addition of Ag and Cu elements can increase the volume proportion of(Cu, Ni)6 Sn5 and Ag3 Sn in the solder alloy, hence to increase the shear strength of the solder joints. The solution and precipitation of Bi in the solder alloy can also contribute to the higher shear strength of the modified Sn-Ag-Cu solder joint, although its melting point is decreased to about 213 ℃. Therefore, the shear strength of modified solder alloy with Ni, Sb and Bi elements is higher than that of commercial SAC305.更多还原