基于低温烧结银的航天功率模块基板大面积连接工艺改进

由于传统航空功率模块中大面积基板连接采用锡铅焊料,可靠性不佳,本文采用烧结银进行大面积基板连接,研究了接头的力学性能、断裂模式和显微组织。结果表明:接头力学性能良好,平均剪切强度为45.18 MPa,呈现出内聚失效和韧性断裂模式,粘接层的孔隙率为4.82%,显微结构致密均匀,界面结合良好。改进的大面积烧结银工艺只需印刷一次焊膏,采用快速升温速率提高烧结银致密度,并将烧结压力降至2 MPa,可以满足航天功率模块中基板连接的要求。

Improvement of Low Temperature Large-Area Sintering Silver Process for Aerospace Power Module Substrate Bonding

In traditional aerospace power modules, tin-lead solder with poor reliability is used for large-area substrate connections. In this work, sintered silver is used to join the large-area substrates. The mechanical properties, fracture mode and microstructure of large-area sintered silver joints are studied. The results show that the mechanical properties of the joints are good, and the average shear strength of the sample is 45.18 MPa, showing a cohesive failure and ductile fracture mode. No defects such as voids, cracks or delamination are found in the sintered silver bond-line. The microstructure of the bond-line is dense and uniform with a porosity of 4.82%. It is shown that the improved large-area sintered silver process requires only single printing. By increasing the heating rate to enhance the density of sintered silver and reducing sintering pressure to 2 MPa, the modified process can meet the requirements of substrate bonding in aerospace power modules.