iStock-692516832iNEMI's Next-Generation Solder Materials workshop brought together more than 70 industry professionals from across the electronics manufacturing supply chain to share information and expertise about the drivers and needs for new solder materials development and how to address anticipated manufacturing and reliability challenges. This workshop, held at IPC APEX EXPO in late January, was the first of two solder materials-related workshops scheduled by iNEMI in 2019. The second workshop focused on low-temperature solders and was held April 24 at SMTA China East/NEPCON China in Shanghai. Presentations from the APEX workshop are available online.

Keynotes from Intel and MacDermid Alpha Assembly Solutions set the stage for this lively workshop. Dr. Ashay Dani from Intel shared information about the needs of new multichip package technologies being developed. These technologies ultimately are demanding more of the solder interconnect as it must accommodate more stringent warpage and thermal constraints, as well as meet mechanical, electrical and reliability requirements. Dr. Carl Bilgrien of MacDermid Alpha Assembly Solutions addressed the materials developer's perspective, discussing challenges facing the industry with the development and introduction of new solder materials for the ever-growing range of applications. Material suppliers must develop materials that meet the market needs, not just in terms of reliability and performance, but also for processability and sustainability.

Board assembly requirements were addressed by HP, Flex and Raytheon. There are many materials coming onto the market, and qualifying them is an expensive and timely process. They also highlighted the need to simplify the qualification process. Manufacturing and reliability challenges for these newer materials were addressed by Intel, Nokia, DfR, Indium and Purdue University. A key point made by all was the importance of good material characterization to understand how they will perform.

The day concluded with break-out groups focused on topics chosen by the attendees: high-reliability applications, voiding in solder interconnects and low-temperature solder. The key outputs of each group are highlighted below. Opportunities for collaboratively addressing some of the challenges highlighted by the break-out groups were also identified.

High-reliability applications. The high-reliability group identified the need to develop standard test suites for high-reliability applications that will ensure the reliability performance of the solder interconnects. They also emphasized the need for better characterization of materials to ensure optimum selection of materials for the more demanding applications. If you are interested in hearing about project proposals in this area, please contact Grace O'Malley.

Voiding in solder interconnects. Focusing on the current voiding acceptance levels and inspection processes in the industry, this break-out group identified a need for better definition of the test and inspection methods across the industry and recommended that these should be expanded beyond BGA packages. In particular, the impact of voiding on reliability performance needs to be studied. The group suggested that iNEMI would provide an excellent forum to collaboratively evaluate and develop best practices and guidelines for input into standards bodies. A follow-up meeting to discuss a proposed project is being arranged for April 30. if you would like to participate in the project discussion meetings, please contact Grace O'Malley.

Low-temperature solder. This discussion group indicated that more work is needed to understand bismuth mixing and diffusion in alloys at similar reflow temperatures. They recommended evaluating other reliability test methodologies, beyond mechanical shock and thermal cycling, and identified the need to develop a robust process window for low-temperature solder alloys. The group also noted that these new materials need to be evaluated for different package types, not just BGAs. For further information on this topic, including iNEMI's ongoing work on the processability and mechanical shock capabilities of bismuth-tin based solders, please contact Haley Fu.