Diffusion barrier property of electroless Ni-W-P coating in high temperature Zn-5Al/Cu solder interconnects
journal contributionposted on 22.06.2017 by Li Liu, Zhiwen Chen, Zhaoxia Zhou, Guang Chen, Fengshun Wu, Changqing Liu
Any type of content formally published in an academic journal, usually following a peer-review process.
The operating temperature of high-temperature electronics can significantly promote the growth of intermetallic compounds (IMCs) at solder/substrate interfaces, particularly for low-cost Zn-based solders because of the rapid rate of reaction of Zn with Cu. Thus, a reliable and robust diffusion barrier is indispensable for suppressing the reactions between solder and substrate. In this work, a ternary Ni-W-P alloy was prepared via electroless plating. Its diffusion barrier property was evaluated by comparing the microstructures of IMC layers in Zn-5Al/Ni-W-P/Cu and Zn-5Al/Cu interconnects after liquid-solid reaction for prolonged durations. When the reaction lasted for 30 min, the thickness of the Al3Ni2 produced in the Zn-5Al/Ni-W-P/Cu solder interconnects was only 2.15 μm, whereas the thickness of the interfacial layer of Cu-Zn IMCs (CuZn4, Cu5Zn8 and CuZn) at the Zn-5Al/Cu interface was 94 μm. Because of the unbalanced growth of the IMCs in the Zn-5Al/Cu interconnects, notable numbers of Kirkendall voids were identified at the CuZn4/Cu5Zn8, Cu5Zn8/CuZn and CuZn/Cu interfaces after prolonged liquid-solid reaction. By contrast, the Al3Ni2 layer in the Zn-5Al/Ni-W-P/Cu solder joints remained intact, showing the potential to effectively enhance the mechanical reliability of electronic devices.
This research was supported by a Marie Curie International Research Staff Exchange Scheme Project within the 7th European Community Framework Programme, No. PIRSES-GA-2010-269113, entitled “Micro-Multi-Material Manufacture to Enable Multifunctional Miniaturised Devices (M6)”, as well as an EPSRC-CPB Funding (GRANT NO. FS14). The authors also acknowledge the research funding by the National Nature Science Foundation of China (NSFC GRANT NO. 61261160498).
- Mechanical, Electrical and Manufacturing Engineering