关键词: CQFP大芯片器件, 安装方位, 失效机理, 焊点热疲劳, 温度循环

Abstract: This study focuses on a large-chip aerospace-grade Ceramic Quad Flat Package (CQFP) device, systematically investigating the effect of component orientation on solder joint reliability under thermal cycling. CQFP devices were mounted on printed circuit board (PCB) assemblies via reflow soldering, with two installation orientations—upright and inverted—designed for comparison. Thermal cycling tests were conducted using a high–low temperature cycling chamber (-55-125 ℃, ΔT=180 ℃), and solder joint fatigue life was analyzed using the Weibull distribution. Results indicate that the characteristic fatigue life of solder joints for inverted CQFP mounting is 235 cycles, representing a reduction of approximately 28.8% compared to upright mounting (330 cycles). Microstructural analysis shows that failures in both orientations predominantly propagate along grain boundaries, with negligible differences in intermetallic compound (IMC) thickness, and creep cracking as the dominant failure mode. Failure mechanism analysis reveals that the superposition of component self-weight and thermally induced mismatch stress in inverted mounting increases tensile–shear combined stress, thereby accelerating solder joint fatigue damage. Based on these findings, reliability enhancement strategies such as underfill reinforcement, solder joint geometry optimization, and process specification improvements are proposed. The results provide a critical reference for evaluating solder joint reliability and optimizing assembly processes for large-size CQFP devices under different mounting orientations in aerospace electronic applications.

Key words: large-chip CQFP devices, mounting orientation, failure mechanism, thermomechanical fatigue of solder joints, thermal cycling