Low temperature alternatives for miniaturized packaging of active implantable medical devices

The technologies presented here provide assembly and packaging technology for miniaturized active implantable medical devices.

Starting from the inside of hermetic implantable capsules, a new approach to realize vertical electrical waterproof feedthroughs with an integration density of up to 192 feedthroughs/cm² is presented. After detailed investigations on the lifetime in corroding environments of different material and parameter combinations hermeticity was confirmed on capsules having up to 44 sealed electrical feedthrough channels.

The incorporation of the developed feedthrough plates into implantable hermetic housings was realized by coating highly stable titanium capsules with a sputter deposited metallization at low temperatures. In combination with thin film coated alumina plates a reliable, long term stable hermetic soft solder seal was created between the alumina and the titanium capsule. This material combination showed no measurable water content in three out of five pre-dried prototypes for more than a year of total submersion in water at 60 °C.

Lastly, the connection of implantable wires to MEMS features like the developed electrical feedthroughs with an integration density of 490 wires / cm² is presented. The novel concept uses a combination of a standard wire bonding tool with a foil-wire assembly at a temperature of 140 °C. The results show a high yield of long-term electrically and mechanically stable connections between the wire and the feedthrough containing metalized alumina substrates.

Several manufactured capsules for implantable electronics demonstrated the applicability of all developed technologies for the time and cost efficient rapid prototyping of reliable miniaturized hermetic assemblies. Furthermore, the technologies proved to be compatible with industry standard implant design.