Long-term behavior of IMCs in lead-free solder joints

This article deals with the creation and growth of intermetallic compounds (IMCs) in solder joints. The test specimens of copper substrate were made for this experiment. The soldered joints were created on the test specimens by hand soldering process at the temperature of 250°C. Four lead-free solder alloys and one tin-lead solder alloy were chosen for research of IMCs. The test specimens were divided into several groups. These groups differ in two parameters. The first parameter is soldering process, concretely soldering time. Half of the specimens were soldered for a period of 10 seconds and the second half of specimens were soldered for a period of 60 seconds. The second parameter is a thermal stress. The test specimens were exposed to elevated aging for research of long-term behavior of IMCs in solder joint. The specimens were thermal stressed in hot air oven at the temperature of 150°C for a periods of 4, 8, 12, 16 and 20 weeks. The results of analysis of IMCs in solder joints using confocal and metallographic microscopes are presented in this article.