Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Patent
1995-03-29
1996-10-08
Kamm, William E.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
22826221, 228175, 65 591, A61N 1375
Patent
active
055627161
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
This invention relates to a construction and method for sealing of a ceramic-metal package, particularly but not exclusively a package for an implantable device.
BACKGROUND OF INVENTION
For implanted devices which acquire power from an external source, a key aspect for satisfactory performance is the efficiency of power transmission to the implanted device. In devices such as cochlear implants, the technique of using an inductive link to transfer power and/or data to the implanted device has been used. Conventional metal packages reduce the efficiency of inductive transfer. One way to address this problem is by utilising a ceramic package containing the receiving coil, instead of the conventional metal package. This arrangement provides reduced attenuation of the RF Field. However, such a package must be effectively sealed, without damaging the components within the package.
One prior art technique is disclosed in U.S. Pat. No. 4,991,582 to Byers et al. Here, the open end of the ceramic package is closed using a metal band bonded to the open end of the package using a metallic braze, and the band is ultimately sealed to a header by spot welding. A similar arrangement is disclosed in U.S. Pat. No. 4,785,827 to Fischer.
in these arrangements, the biocompatability of the resulting package may be compromised by the materials used, particularly the braze. There is also a the risk of degradation or corrosion along, or as a result of, the braze.
SUMMARY OF INVENTION
it is an object of the present invention to provide a ceramic package suitable for use with an implanted device, which avoids the need for brazes in manufacture.
According to one aspect the present invention comprises a hermetically sealed package for an implanted device comprising:
Preferably, the package further includes a further ceramic element bonded to the other side of said flange so as to provide a surface for compression during the bonding procedure.
Preferably a further element is provided adjacent to said flange so as to distribute stresses over the flange/envelope bond. Preferably the further element is a washer.
According to another aspect the present invention comprises a method of forming a weld sealable implantable package, comprising solid state bonding a metal flange to a ceramic envelope by compressing them together at a temperature and pressure and for a duration sufficient to effect bonding.
Preferably said method further comprises bonding a further ceramic element to the other side of said flange.
BRIEF DESCRIPTION OF DRAWINGS
One embodiment of the invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 illustrates a package formed according to the invention, partly in section;
FIG. 2 illustrates the package of FIG. 1 in section about a perpendicular axis;
FIG. 3 illustrates in more detail the bonded flange joint according to this embodiment;
FIGS. 4 and 5 are further views illustrating this joint;
FIG. 6 is a view into the unsealed package; and
FIGS. 7A and 7B illustrate the preferred bonding of the hermetic seal according to one aspect of the invention.
DISCLOSURE OF INVENTION
The present invention uses a solid non-liquid bonding technique to join the ceramic envelope to a platinum flange, and then the flange is bonded to a feedthrough assembly at a later point. The advantage of this arrangement is that no brazing is required during manufacture. Additionally, the resulting construction is structurally sound, and can be readily sealed by welding.
FIGS. 1 and 2 illustrate the assembled package 10 according to the preferred embodiment of the present invention. Ceramic envelope 2 encloses RF receiving coil 1, feedthrough assembly 5, and the other operative components of a cochlear implant receiver-stimulator unit. The precise operation and configuration of the implanted device are irrelevant to the present invention. The envelope 2 may be made from any suitable ceramic, preferably a high alumina ceramic. The envelope 2 is bonded to platinum flange 3, and flange 3
REFERENCES:
patent: 4050956 (1977-09-01), de Bruin
patent: 4517738 (1985-05-01), Fukuoka et al.
patent: 4693409 (1987-09-01), Mizunoya et al.
patent: 4991582 (1991-02-01), Byers
patent: 5046242 (1991-09-01), Kuzma
Cochlear Limited
Kamm William E.
Schaetzle Kennedy J.
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