Electric breakdown mechanism of build-up films under high-temperature and high-humidity conditions

Electronic products have been evolving towards high performance and high integration to meet the demands of high-performance computing, next-generation mobile communication, artificial intelligence, automotive electronics, and defense equipment. In order to achieve the highest wiring density and optimize electrical performance, flip-chip ball grid array (FCBGA) substrates are developed, utilizing multiple high-density wiring layers, laser blind vias, buried vias, and stacked vias, along with ultra-fine pitch metallization. Currently, FCBGA packaging is widely used in high-performance processors, graphics processors, network chips, communication devices, and consumer electronics. With the increase of integration level, the quality and reliability of FCBGA packaging have been highly concerned. FCBGA packaging substrates typically employ build-up films as the interlayer insulation material. The breakdown strength performance of build-up films under high-temperature and high-humidity environments is crucial to their reliable operation. Recent studies have made significant strides in elucidating breakdown strength mechanisms. However, despite these research efforts, breakdown strength research still faces formidable challenges. For instance, the complexity of breakdown mechanisms, especially in high-energy, high-frequency, and complex environments remain controversial. The intricate relation between material properties, environmental factors, and electric field characteristics complicates the understanding of breakdown variation of build-up films This study simulated real operating conditions by subjecting samples to different conditions, comparing the trend of breakdown strength performance changes of build-up films after biased highly accelerated stress tests (BHAST). It was found that moisture ingress was the most significant factors damaging the insulation performance of build-up films, leading to the decrease in breakdown strength. When the moisture content in the build-up films increased from 0.05% to 0.49%, the breakdown strength decreased from 332 kV/mm to 250 kV/mm