Effect of Ag Sintered Bondline Thickness on High-Temperature Reliability of SiC Power Devices
Zhongyang Deng, Guisheng Zou, Qiang Jia, Bin Feng, Hongqiang Zhang, Hui Ren, Lei Liu
Abstract
Nano-Ag sintering is a promising die-attach technology for the wide bandgap semiconductive power devices, while the high cost of nanosilver limits industrial application. Reducing bondline thickness (BLT) is effective for cost-saving but its effects on reliability have been rarely studied, especially at high-temperature operation. In this work, an organic-free nanostructured silver film was prepared by pulsed laser deposition (PLD) for various BLT joints. The effect of BLT (3.5– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$60~\mu \text{m}$ </tex-math></inline-formula> ) on the high-temperature reliability of die-attached modules was systematically investigated. The results indicated that with the increase of BLT, the shear strength and power cycling number of joints both increased. The optimal BLT ranged in 25– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\mu \text{m}$ </tex-math></inline-formula> considering both reliability and cost. It was very interesting to find that the connection ratio along the BLT direction existed two valleys at the die- and DBC-bondline interfaces, which clearly corresponded to the crack propagating in the power cycling test.