High-temperature electronics packaging for simulated venus condition

An electronic packaging technology that survives the simulated Venusian surface temperature of 465°C and 96 bar pressure in carbon dioxide (CO2) and nitrogen environments, without the corrosive trace gases, was developed. Alumina ceramic substrates and gold conductors on alumina were evaluated for electrical and mechanical performance. The most promising die-attach materials are thick-film gold and alumina-based ceramic pastes. Alumina, sapphire, silicon, and silicon carbide dies were attached to the alumina substrates using these die-attach materials and exposed to 96 bar pressure in a CO2 environment at 465°C for 244 h. The ceramic die-attach material showed consistent shear strengths before and after the test. An alumina ceramic encapsulation material was also evaluated for thermomechanical stability. The devices on the packaging substrates were encapsulated by a ceramic encapsulation with no significant increase in cracks and voids after the Venusian simulator test. Wire pull strength tests were conducted on the gold bond wire to evaluate mechanical durability before and after the Venusian simulator exposure. The average gold bond wire pull strengths before and after exposure were 5.78 g-F and 4 g-F for 1-mil gold bond wires, respectively, meeting the minimum MIL-STD-885 2011.9 standard. The overall wire bond daisy chain resistance change was .47% after the Venus simulator test, indicating a promising wire bond integrity. A titanium package was fabricated to house the ceramic packaging substrate and a two-level metalized feedthrough was fabricated to provide electrical interfaces to the package. © 2020 International Microelectronics Assembly and Packaging Society and alumina-based ceramic pastes were evaluated. Gold wire bonds were used to electrically connect the various electronic dies and packaging substrates. Some of the devices on the packaging substrates were encapsulated by a glob-top ceramic encapsulation. The high-temperature packaging substrates, with and without the encapsulation material, were exposed to 500°C for at least 100 h as well as thermal cycling from room temperature to 500°C. These packaging structures were further exposed to a simulated Venus environment test chamber at 465°C and 92-96 bar pressure in a CO2 environment. The test results showed that these packaging materials survived the simulated Venus's surface environment for up to 244 h. A titanium package to house the high-temperature packaging substrates was fabricated to provide electrical interfaces to the package.