MULTILAYER COMPOSITE MATERIAL VIAS
Novel multilayer composite material vias for biological implants are disclosed. The vias comprise two metals, so that the metal more compatible with biological environments is on one end of the via, and the metal more compatible with fabrication of a hermetic package is on the other end of the via.
1 . A hermetic package comprising
a container;
a ceramic substrate bonded to the container; and
a least one via through the ceramic substrate including
at least one layer of a first metal paste, including a first metal, and
at least one layer of a second metal paste, including a second metal different from the first metal;
wherein the container, ceramic substrate and via form a hermetic seal.
2 . The hermetic package according to claim 1 , wherein the first metal is platinum and the second metal is tungsten.
3 . The hermetic package according to claim 2 , further comprising a plurality of tungsten layers.
4 . The hermetic package according to claim 1 , wherein the hermetic package is part of a biological implant.
5 . The hermetic package according to claim 1 , wherein at least one via comprises interlayer circuitry.
6 . The hermetic package according to claim 1 , wherein the at least one layer of the first metal is on an outside surface of the hermetic package and the at least one layer of the second metal is on an inside surface of the hermetic package.
7 . The hermetic package according to claim 6 , wherein the first metal is platinum and the second metal is tungsten.
8 . The hermetic package according to claim 7 , further comprising a plurality of tungsten layers.
9 . The hermetic package according to claim 1 , wherein the container is metal.
10 . The hermetic package according to claim 9 , wherein the container is brazed to the substrate.