Hoenle’s Structalit 8205 underfill for automotive power electronics survives 1,000 thermal cycles

Hoenle Adhesives has introduced Structalit 8205, a specialised underfill material designed for use in automotive power electronics, advanced driver-assistance systems (ADAS), and high-performance computing. This product targets flip chips, ball grid arrays (BGAs), and chip-scale packages (CSPs), providing mechanical reinforcement to solder joints by filling the space beneath components. This reinforcement is crucial in automotive environments where electronic modules face continuous vibration and wide temperature fluctuations. Structalit 8205 employs a filler-modified epoxy formulation that reduces the coefficient of thermal expansion, thereby minimising stress caused by temperature changes between the component and the circuit board. The material demonstrated impressive durability in testing, surviving 1,000 thermal cycles between −40 °C and +100 °C without solder joint failure, and withstanding over 100 cycles between −65 °C and +150 °C without any cracking. Such resilience highlights its suitability for demanding automotive applications where reliability is paramount. The underfill flows via capillary action at relatively low temperatures (80–100 °C), ensuring void-free coverage beneath components and maintaining a keep-out zone below 300 micrometres. It is compatible with standard dispensing equipment, including jetting systems with flat nozzles, which operate between 60 and 90 °C. Additionally, Structalit 8205 supports rapid thermal curing, enabling manufacturers to maintain efficient production cycle times. By addressing the mechanical and thermal challenges faced by modern automotive electronics, Structalit 8205 offers a robust solution to enhance the longevity and performance of critical power and control modules. Its development reflects ongoing industry efforts to improve the reliability of electronic assemblies in increasingly harsh operating conditions, particularly as electric and autonomous vehicles become more prevalent.