A novel packaging technology for miniaturization of active long-term implantable medical devices enabling new medical applications

A novel long-term biocompatible package and its manufacturing method have been developed. The package is made of sapphire and is fabricated on a wafer level. Sapphire substrate to sapphire lid hermetic sealing was demonstrated at a temperature of less than 120°C in the package cavity, using long-term biocompatible materials. Feedthrough with multiple electrical interconnections was manufactured in sapphire using only biocompatible metals like platinum or platinum-iridium (PtIr). The developed package showed a shear strength of higher than 100MPa for both the seal and feedthrough. Hermeticity was confirmed using destructive helium spraying leak testing. The test showed that the packages were leak tight below the noise floor of the measurement equipment, ~1 × 10^-10 atm cm³ s^-1. A production oriented non-destructive leak test method which is critical during production was developed using Fourier Transform Infrared (FTIR) spectroscopy. The detection limit was evaluated for two test vehicles. A leak rate lower than 1×10^-12 atm cm³ s^-1 was demonstrated for 1.4 mm³ cavities. A longer bombing time can confirm a 10 year lifetime hermeticity.