Electrical insulation of implantable devices by composite polymer coatings

Protection of implanted integrated circuits has required hermetic sealing, usually in metal containers and usually in package sizes that would preclude implantation in small and confined areas of the body. We have developed a method whereby ultrathin (10 micron) composite films consisting of glow discharge and vapor deposited polymers can be placed directly over integrated circuit substrates to provide protection from water and ions for up to 30 days (our present test limits). Our paper describes the reactor, surface preparation, and polymerization conditions necessary to obtain the water/ion resistant coatings. Results indicate little change in leakage current when comb patterns with 10 micron line widths and our insulating composite coatings are exposed to physiological saline solution and a 3 VDC bias.