Use of Digital Signal Characteristics for Solder Joint Failure Precursors

Electronic systems are exposed to stress conditions during their life cycle. Chemical substances such as moisture and acid are the major source of stresses. The chemical stress condition can induce chemical degradation of electronic components and interconnects including solder joints. Chemical degradation often leads to malfunctions of electronic systems, ultimately resulting in system failure. To monitor damages of the electronic system, measurements based on DC resistance are often used as a system health indicator because they can clearly show the electrical discontinuity. However, DC measurement often requires additional sensing devices or circuitry to detect failure with actual electronic system. This paper introduces a new approach to detect degradation of an electronic system. Using the skin effect of digital signals, we demonstrate that the digital signal enables detection of solder joints degradation under chemical stress condition. We designed an accelerated life test (ALT) to apply chemical stress to solder joints by acid. Digital signal integrity was continuously monitored simultaneously with DC resistance during the ALT to identify the failure precursor of the solder joints. The experimental results indicate that digital signal integrity is gradually deteriorated during solder joint degradation prior to complete electrical open state. The proposed approach based on the digital signal used in the electronic system does not require additional devices. Thus, it is more adaptable than the existing DC measurement in managing the health of actual electronic systems.