Radiance Technologies

Effect of Soldering Parameters on Reaction Kinetics and Phase Transformations of SAC 305 Solder

Jul 08, 2010 | T. Ryno, A. Kelley, J. Metzger, and D. Medlin; Department of Materials and Metallurgical Engineering, South Dakota School of Mines and Technology | C. Voyles, S. Richards; Radiance Technologies

As technology becomes increasingly reliant on electronics, understanding the reliability of lead-free solder also becomes increasingly important. This research project focused on phase transformation kinetics with the lead-free solder SAC 305. Today in the electronics industry, SAC 305 is the most widely used solder, making it a high priority to understand its long-term stability and performance in a variety of service conditions. Recent evidence has shifted the focus from thermal aging to reflow temperature and time above liquidus values during initial solder melting....

Effects of Thermal Aging on Copper Dissolution For SAC 405 Alloy

Jul 08, 2010 | Dr. Dana Medlin, Clay Voyles, Teneil Ryno, Casey Bergstrom, John Metzger, and Spencer Richards

Aging characteristics of new lead free solder alloys are in question by many experts because of higher amount of tin’s effect on the diffusion of other metals, primarily copper, to create undesirable boundary intermetallics over long periods of time and even moderately elevated temperatures. A primary layer of intermetallics, Cu6Sn5 forms as the liquid solder makes contact with the solid copper substrate. This reaction however ceases as the solder temperature falls below that of liquidus. A secondary intermetallic Cu3Sn1, an undesirable weak and brittle layer, is thought to form over time and may be accelerated by even mildly elevated temperatures in electronic modules such as laptops under power.

This project was designed to quantify the growth rate of Cu3Sn1 over an extended period of time in a thermal environment similar to a laptop in the power on mode....