Lead-Free Solder for Assembly of Thick-Film Hybrid Modules for Use in High-Temperature Applications

High lead solders have long been used for the assembly of underhood automotive thick-film hybrid modules. With the move to lead-free solders in the electronics industry, there is an increasing interest in alternatives to high lead solders in these applications. A AgBiX solder paste has been evaluated for SiC die and resistor attach for 200°C applications in vehicles. Die attached to thick-film Ag metallized substrates showed no degradation in shear strength after 2000-h aging at 20°C, while die attached to PdAg thick-film metallization exhibited a decrease in shear strength of ~30%. After 2000-h aging at 200°C, chip resistors showed a decrease in shear force at fracture of ~44% and 60% for assembly on thick-film Ag and thick-film PdAg, respectively.