Hermetic power package

Abstract

Hermetic power packages are devices in which power-consuming chip devices or integrated circuits which generate considerable amounts of heat can be mounted and which provide thermally integral heat sinks. Terminal and lead-bearing alumina rings or collars, unified by firing, provide hermetically sealed insulated buried leads.

Description

This application is a reissue application of my application Ser. No. 109,888, filed Jan. 26, 1971, and issued Aug. 1, 1972 as U.S. Pat. No. 3,681,513. before firing from the segments of FIG. 6 which shows individual segments of green ceramic sheet employed in assembling the alumina ring of FIG. 5.

FIGS. 7 and 8 show plan and cross-sectional views respectively of an hermetic power package in another embodiment of this invention.

FIG. 9 shows an exploded view of the hermetic power package of FIGS. 7 and 8.

FIG. 10 shows portions of the green ceramic tape employed in assembling the alumina which are fired. The three separate segments shown in FIG. 6 are intended to show the structures repeated in each larger sheet. It will be noted that the orientation of the parts in FIG. 6 is rotated 90° clockwise from ring 12 in FIG. 4 and FIG. 2. While in sheet form, conductive patterns and overlap connectors are screened or otherwise applied to the sheets as needed. Thus, pattern 50 with overlap connector 52 is screened on sheet 30, patterns 60, 61, 62 and 63 with overlap connectors 64 and 65 are screened on sheet 32 and patterns 70 on the upper surface and 72 on the under surface with overlap connector 74 and 76 are screened on sheet 32. It will be seen that the hole 80 in sheet 30 is larger than holes 82 and 84 in sheets 32 and 34 so that when assembled portions of patterns 60, 61 and 62 are inside and outside of the ring, the triangular shorting bar 18 which fits notch 42 after firing will be seen to contact pattern 70 and by means of overlap connector 65 then contacts pattern 63. For some purposes, variations in electrical structure may be made such as omission of overlap connector 65.

Another embodiment of the invention is shown in FIGS. 7, 8, 9 and 10. It will be seen from FIG. 10 that the ceramic ring 90 of FIG. 9 is made up by joining two green sheets 92 and 94 bearing conductive layers 100, 102, 104 and 106 and then firing. Although for convenience sake sheets 92 and 94 are shown with a line of division at their junctive in FIG. 9, they are, of course, integrally bonded by firing there and in FIGS. 7 and 8, although in the latter, which is a section of FIG. 7 along line 8--8 no contact of the ceramic layers is evident.

This embodiment is best understood by reference to the exploded view in FIG. 9 in which rectangular heat sink 110 forms the base to which are brazed ring 90 and beryllia wafer 116 having metal coatings 115 and 117 in the bottom and top respectively. Brazing of beryllia wafer 116 and expansion shim 118 to base 110 is assisted by brazing preform 111 and of ring 90 to expansion shim 118 by brazing preform 112. Lead frame 119 is attached to contact surfaces 104 and 106 of ring 90 using the pair of brazing preforms 113 and low expansion ring 120 is brazed to the upper surface 100 of ring 90 using brazing preform 114. Ring 120 providing a suitable surface for attachment of a lid (not shown) after mounting a power unit (not shown) within the container. Brazing metal is not shown in FIG. 8 and the metal surfaces joined by brazing are not shown separately. For the same reason, indicia are not applied to such metallic surfaces in either FIGS. 7 or 8 where an integral unit is shown. The assembled unit of FIGS. 7 and 8 is conveniently gold plated by tumbling or other suitable technique.

It will be apparent to those skilled in the art that numerous other variations in structure are possible within the scope of the invention. For example, by modification of the ceramic ring to have numerous leads or to be of particular shapes or sizes.

Claims

1. A package adapted for a power-consuming chip device comprising:

A. a metallic heat conductive base

B. a low expansion metallic shim brazed to said base and,

C. a terminal-bearing and lead-bearing alumina ceramic ring or collar having a central opening and having metallic surfaces at least partially covering the top and bottom surfaces, and external terminals connected to internal terminals within the central opening by buried leads, said ring or collar being sealed to said base by brazing to said shim and surrounding an area of said base adapted to receive said chip device.

2. A package adapted for a power-consuming chip device according to claim 1 having a substantially central opening in the low expansion metallic shim approximately corresponding to the area surrounded in the terminal-bearing and lead-bearing alumina ceramic ring or collar.

3. A package adapted for a power-consuming chip device according to claim 1, having a bilaterally metal-coated beryllia chip attached to the base within the area surrounded by the terminal-bearing and lead-bearing alumina ceramic ring or collar and adapted for attachment of a chip device to the base with electrical insulation and thermal conduction.

4. A package adapted for a power-consuming chip device according to claim 1 wherein a low expansion metallic ring is attached to the upper surface of the terminal-bearing and lead-bearing alumina ceramic ring or collar to provide a base for attachment of a covering lid.