The effect of solder alloys and surface finishes on the thermal cycling reliability of different electronic packages

Abstract

Electronic products have become essential in modern society, powering everything from communication devices to critical infrastructure. Eutectic SnPb (Tin-Lead) solder has been used in electronics since the early days due to its excellent mechanical and electrical properties, making it a reliable choice for soldering applications. However, by the late 20th century, the harmful effects of lead were recognized, prompting a shift towards lead-free electronics. In response to these issues, the industry engaged in extensive research to find suitable alternatives, ultimately leading to the development of near-eutectic alloys based on tin (Sn), silver (Ag), and copper (Cu), known as SAC solder alloys. In everyday applications, solder joints endure thermal and mechanical stresses, causing the microstructure to evolve and the mechanical properties to degrade, ultimately leading to component failure. Over time, solder materials have shifted from traditional SnPb alloys to lead-free alternatives, later incorporating dopants like Bismuth (Bi), Antimony (Sb), and Nickel (Ni), which have been shown to enhance thermal and mechanical performance. While the literature has examined solder alloys and their function, the reliability of solder joints, particularly in an extensive context based on joint shape and surface finishes under thermal cycling conditions, remains unexplored. This research focuses on the reliability analysis of a series of electronic packages (CABGA, CVBGA, MLF, and SMR) subjected to thermal cycling using various solder alloys, and surface finishes. The study is designed to evaluate how these factors influence the characteristic life and failure mechanisms of solder joints for different components under harsh environmental conditions. A combination of traditional methods, such as Weibull analysis, along with advanced machine learning techniques, is employed to identify the most critical factors affecting reliability. Furthermore, a novel approach based on the Maximum Entropy Principle is developed and tested to create a more accurate predictive model. Moreover, this research develops and utilizes a new algorithm and software to monitor data in thermal cycling tests. This research aims to contribute to understanding solder joint reliability and provide improved models for predicting the lifetime of electronic components in industrial applications.