Aging Effect on Drop-Shock Reliability of SnAgCu305 Solder Alloy

The reliability of solder joints plays a crucial role in various electronic applications, as it directly impacts the overall performance, durability, and safety of electronic devices. With the global transition towards lead-free alloys, understanding the aging effects on the drop-shock reliability of these alloys has become a primary consideration. Solder joints are pivotal components in electronic assemblies, frequently containing intermetallic compound (IMC) particles such as silver-tin (Ag3Sn) and copper-tin (Cu6Sn5). During the aging process, these particles tend to course, leading to changes in the structural characteristics of solder joints. This study conducted a comprehensive drop-shock reliability test on SnAgCu305 alloy, focusing on three different aging durations: 0, 2, and 10 days, all performed at a homologous aging temperature of 125 ℃. The test involved using a chip array ball grid array (CABGA208) component with specific characteristics, including a 0.8 mm pitch and a 15 mm body, which was carefully assembled to a test vehicle with Immersion Tin surface finish and Immersion Gold surface finish. The tests were performed with a peak acceleration of 1500 G and a pulse width of 0.5 ms. Cross-sectioning and microstructural analysis were carried out to investigate the correlation between the growth of intermetallic compound particles and drop reliability. The study revealed that prolonging the aging time had a direct impact on increasing the size of the IMC particles and the thickness of the IMC layer, resulting in solder joints becoming less reliable. Consequently, there was a significant decrease in the number of cycles required for failure.