The evolution in modern-day electronics extends beyond miniaturization and significantly increases the number of power cycles operating with low temperature swings (few tens of degrees). This shift has raised the reliability requirements and expectations for electronics systems to last longer. The transition of vehicles and autonomous systems to zonal architectures, driven by electrification, has increased power-on hours of electronic components, leading to higher system complexity and more challenging reliability testing. Currently, standardized stress- based tests and predictive models have constraints, as they are designed for large temperature swings and are inaccurate for evaluating low T conditions. Additionally, the damage caused by Δ millions of low thermal swings is less explored in simulation and qualification, making it important to analyze the influence of low ΔT on solder joints to understand field reliability risks.An Arduino-based testing setup was developed to apply active thermal cycles to WLCSP40 using relay-controlled switching with 6-second cycles. Samples were tested from 50k to 800k cycles to analyze the long-term damage accumulation under such conditions. In addition to experiments, a thermomechanical simulation in COMSOL incorporated ΔT values obtained from thermal camera characterization to establish realistic boundary conditions. It helps to correlate experimental results and identify critical locations within the solder joints where damage is most likely to occur.Cumulative plastic strain analysis and cross-sectional imaging revealed cracks in the solder bulk at 40 °C, demonstrating microstructural fatigue under low ΔT cycling. Furthermore, based on strain per cycle values, the results exhibit how the active and passive thermal cycles differ.

The heat produced within the device in its package depends on the power supplied to each IP block. The improper placement of an IP block with high power consumption can become a reliability risk for IC packages, as it can significantly affect the reliability of solder balls due to thermal, mechanical, and electrical factors. It also mitigates the effect of thermal cycling, because it depends upon heat management within the package. Improper IP block placement can block heat flow paths, which results in poor thermal dissipation and higher temperature which can create a higher strain on the solder balls affecting their lifetime. Therefore, it is crucial to understand the interplay between the correct placement of IP blocks and solder balls to enhance solder ball reliability. COMSOL-based simulation study will be done on a WLCSP (Wafer Level Chip Scale Package) mounted on a PCB board on which solder balls are connected to copper layers on the die and PCB sides. Variations in the placement of the IP blocks. Thermal cycling and the variations in the placement of the IP block within the package will be taken as a loading condition. Therefore, this influences the susceptibility of device failure due to solder ball fatigue. Based on board-level passive cycling, the solder balls which are located under the IP blocks are the most likely ones affected by this stress. The results will be analyzed to optimize the layout of the IP blocks, concerning accumulated plastic strain on the solder balls at different locations of the IP block placement. It can help to understand the influence of the position of the IP block, reduce stress concentration, and minimize thermal cycling effects, which leads to an increase in the reliability of the solders joint and IC package itself.

Electronic packages with solder interconnects, such as Chip Scale Packages (CSP) and Ball Grid Arrays (BGA), are extensively utilized in various applications, including cell phones, smartwatches, and electric vehicles. The advancements in technology and the features within these applications have led to an increase in power cycles within the packages. This combined with a reduced time to market makes their reliability testing more challenging. With the increased power cycles, even the small temperature variations (ΔT) within an Integrated Circuit (IC) package contribute to the increased susceptibility of devices to failures, often triggering a complex interplay of competing failure modes. Thus, it is crucial to understand the interplay between various failure mechanisms in real-world scenarios for evaluating and overseeing the dependability and efficiency of electronic systems. This paper presents an overview of the impact of small temperature variations on component reliability. In addition, a simulation-based preliminary study is carried out on a Wafer-Level Chip Scale Package (WLCSP) by implementing a thermal load corresponding to an active power cycle. The results are analyzed to locate possible failure locations within the solder bumps based on the accumulated plastic strains for different amplitudes of thermal load (ΔT). Finally, the necessity for a new testing strategy based on variable (ΔT) is highlighted.