High-Temperature Double-Layer Ceramic Packaging Substrates

A double-layer ceramic electronic packaging technology that survives the Venusian surface temperature of 465°C was developed using a ceramic interlayer dielectric with gold conductors. A 60-μm ceramic interlayer dielectric served as the insulator between the top and bottom gold conductors on high-purity ceramic substrates. Test devices with AuPtPd metallization were attached to the top gold pads using a thick-film gold paste. Thermal aging for 115 h at 500°C and thermal cycling from room temperature to 450°C were performed. Dielectric leakage tests of the interlayer ceramic layer between the top and bottom gold conductors revealed a leakage current density of less than 50 × 10−7 A/cm2 at 600 V after thermal cycling. Gold conductor resistance increased slightly after thermal cycling. The die shear test showed a 33% decrease in die shear strength after thermal tests and its 6.16 kg-F die shear strength satisfies the Military Standard Product Testing Services (MIL-STD) method.