Transient liquid phase bonding using Ni/Sn multilayers for high temperature applications

• Main Author: Melvin
• Other Authors: Chen Zhong
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/55856
• Institution: Nanyang Technological University

With growing demand in electronic system for operating in harsh conditions makes the idea of research focus more on a reliable and resilient packaging of the interconnect components. The components of these devices are subjected to wide range of temperatures therefore the reliability and resilience of the components must be sufficient to produce a device with an acceptable lifetime. Some conventional solder joints have been experimented but they were proven to have a lower melting point than the service temperature, making them become inappropriate candidates for high-temperature applications. Consequently, a new bonding method which incorporated both dissolution bonding and diffusion bonding i.e. Transient Liquid Phase (TLP) bonding is developed for addressing this issue. Moreover, its benefits to produce high quality bond at lower processing temperature has made this method as a prominent method particularly for bonding metallurgical systems. Nickel-Tin (Ni-Sn) metal system was proposed as a die-attach solution for high-temperature applications since it was cost effective, high remelting temperature and compatible with manufacturing process. In this project, Ni-Sn metal system was fabricated using TLP bonding and further studies were carried out to investigate its shear strength reliability both at room temperature and elevated temperature. In addition, influence of thickness of Ni and Sn layers and aging treatment on the joint strength were also discussed. Developed TLP joints were taken for die-shear test for testing the mechanical strength of the joint. Increasing joint strength was observed given an increase in Ni and Sn layers. Microstructural changes as a result of aging treatment were also analyzed by SEM and EDX. X-Ray analysis showed no occurrences of voids and the joint merely consisted of Ni and Ni3Sn4 layers. From shear strength evaluation, Ni-Sn TLP of thicker Ni and Sn layers met the minimum shear strength for high temperature applications as die attach bond under room temperature service. On the other side, aging treatment at 100 hour showed the formation of thicker Ni3Sn4 layer and the presence of abundant oxygen concentration at the joint area which resulted in joint strength reduction. Moreover, at 200-hour aging time, thinning of Ni3Sn4 layer was observed along with the absence of oxygen molecules at the joint area which further exacerbated the quality of TLP joint.