Hermetic glass soldered micro-packages for a vision prosthesis.
Micro-packages based on alumina ceramics hermetically sealed with glass solder were fabricated and tested over a 1.5 years period under accelerated aging at 85 °C. A device for sealing the 1.2 mm high, and ø10mm packages while cooling the critical centre of the package containing the electronics was developed. Heating of the rim up to 550 °C while maintaining the package centre below 300°C was successful, allowing a symmetrical heating of the device during the sealing procedure. The fabricated packages with an inner volume of 0.05 cc were backfilled with helium and tested for hermeticity with a fine leak tester. Samples passing the fine leak (1•10(-12) atm•cc/s) test were attached to a larger chamber containing a humidity sensor. Some devices covered in PDMS and some directly exposed were stored at 85 °C in water to measure the humidity intrusion into the device due to deterioration of glass solder. 1 out of the 8 successfully fabricated devices failed after 5 years extrapolated lifetime. Two of the devices have kept constant humidity levels while others gradually rise. Nevertheless, 7 out of 8 have maintained a level below 17,000 ppm humidity. Furthermore, the deterioration of glass solder was electrically and optically studied over a year's period showing no corrosion of glass if properly coated in PDMS.
Laboratory for Biomedical Microtechnology, Dept. of Microsystems Engineering-IMTEK, Univ. of Freiburg, Germany. ordonez@imtek.de
Juan
J
Ordonez
Philip
P
Dautel
Martin
M
Schuettler
Thomas
T
Stieglitz
D005898:Glass / Q000737:chemistry*; D057488:Visual Prosthesis / Q000737:chemistry*; D015035:Zinc Oxide-Eugenol Cement / Q000737:chemistry*
C510255:Hermetic; D015035:Zinc Oxide-Eugenol Cement