Inhibition mechanism of palladium on intermetallic compounds in Au–Al bonding under high temperature storage

Purpose Adding Pd element to Au wire can improve the reliability of Au-Al bonding, but the mechanism of Pd element has not been well revealed so far. The purpose of this study is to reveal in more detail the mechanism of the role of Pd elements in Au/Al bonding. Design/methodology/approach In this paper, the microstructure changes and tensile data of 99.99% (4N) gold wire and 99% (2N) gold wire with 1 at % Pd were compared through high-temperature thermal aging treatment of the specimens, so as to explore the influence mechanism of Pd element on Au-Al bonding reliability. Findings The addition of Pd element effectively reduces the thickness of intermetallic compounds (IMCs) layer and strengthens the fracture tension and reliability. Compared with the 4N specimen, the average thickness of the IMCs layer of the 2N specimen under the same conditions is reduced by 1 µm, and the tensile value of the 2N specimen is increased by 1−3 g. Stored at 200°C for 200 h, the failure rate of bond point of 4N specimen reached 94.64%, and that of 2N specimen was 20%, with a difference of 4.73 times. Originality/value Through comparative analysis of the data, this study found that the doping of Pd element in Au-Al IMCs in the early stage slowed down the growth rate of the IMCs, and the precipitation of Pd element in the late stage to form a better Pd-rich layer hindered the element mutual diffusion behavior between Au and Al.