Solder Ball Alloy Effect on Board Level Reliability Thermal Cycling and Vibration Test Enhancement

The selection of solder alloys for package terminals is critical for products after surface mount assembly process in terms of reliability and lifetime. In this study, a board-level reliability test was applied to evaluate the performance of the different types of lead-free solders. Intermetallic compounds (IMC) affect the mechanical properties of solder joints and the reliability performance of automotive electronic products. IMC and solder fracturing are common defect modes in ball grid array balls. This study used a daisy-chained test vehicle of 167 ball grid array package with a 0.35-mm fine ball pitch. Thermal cycling and vibration tests were conducted in accordance with JEDEC test methods and guidelines. It is known that indiumdoped solder and high-Ag solder alloys exhibit enhanced mechanical properties. To this end, this study presents a comparison of the IMC and solder crack propagation and the ratio between two types of solder balls, SAC <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$305\text{Ni}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SAC}405\text{NiBiIn}$</tex>. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SAC}405\text{NiBiIn}$</tex> alloy showed significant improvements under vibration and thermal cycling conditions. The results indicate that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SAC}405\text{NiBiIn}$</tex> can reduce the solder ball crack ratio by 40% after vibration testing and 53% after 1500 cycles of thermal cycling. Weibull statistics showed that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SAC}405\text{NiBiIn}$</tex> directly improves the lifespan of electronic devices.