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iNEMI Launching Project on Electromigration of SnBi Solder for Second-Level Interconnect

New iNEMI project will addres the problem of electromigration in SiBn solders and the resulting risk of brittle solder joints with high electrical resistance over time in the field.
The low melting temperature of SnBi alloys (138°C) makes them attractive for assembling thermally warpage-prone high-density microelectronic packaging. However, Bi has a high propensity for electromigration and segregation at the anode under high current density conditions. This can lead to potentially brittle solder joints with high electrical resistance over time in the field. There is a need to mitigate this shortcoming and develop SnBi solder joints that maintain their performance and reliability over the product life. iNEMI's Electromigration of SnBi Solder for Second-Level Interconnect project will explore ways to mitigate this issue and develop Sn-Bi solder joints that maintain their performance and reliability over the product life. 

Project Objective
The overall project objective is to determine the boundaries of the envelope formed by joint height, temperature, current density and PCB finishes within which the solder joint will operate reliably over the product life. 

The project has multiple phases planned. The first phase will:
  • Establish an appropriate test vehicle for electromigration study of solder joints, including a convenient means of achieving various joint heights.
  • Investigate the role of back pressure in reducing electromigration in eutectic SnBi solder joints by determining the rate of electromigration of SnBi solder joints with and without diffusion barriers as a function of current density, temperature and joint height.

If you want to participate in, or if you have any questions about, the project please contact Haley Fu (haley.fu@inemi.org). For additional information (including webinar presentation and recording from the project's call-for-participation webinar).