BACKGROUND OF INVENTION It is currently the state of the art to machine expensive base plates, which act as heat dissipaters for electronics inside a package. These heat dissipaters are commonly made of materials such as copper, molybdenum, copper-molybdenum, and cooper-tungsten. Other materials can be used such as Aluminum, AlSiC, silver, gold, and post plated materials. These base plates or heat dissipaters are then brazed to glass-to-metal sealed kovar or CRS frames. Most of the expense of the package at that point is attributed to the material cost of the heat dissipative alloys and the extensive machining required.

SUMMARY OF INVENTION It is the object of the invention to provide an economical method for inserting heat dissipative plugs into electronic enclosures where needed to suit the electronic characteristics of the package. The plugs are made to the required size and shape as needed to provide appropriate heat dissipation for the electronic package. The plugs are made in an appropriate manufacturing process such as a screw machine. This greatly minimizes the material cost and manufacturing cost of the heat dissipaters. Currently, hermeticity has only been checked for kovar and copper-tungsten dissipaters. Other shapes and designs are possible.

The plugs are then inserted into a counterbored hole in the electronic package through a coining operation. The stamping operation wedges the two pieces together and provides a hermetic seal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a perspective view of one embodiment of heat dissipative plug of the present invention.

FIG. 2 depicts a perspective view of a mating electronic enclosure for the plug of FIG. 1.

FIG. 3A depicts a cross-sectional area of a hard metal heat port and base plate prior to stamping.

FIG. 3B depicts a cross-sectional area of a hard metal heat port and base plate after stamping.

FIG. 4A depicts a cross-sectional area of a soft metal heat port and base plate prior to stamping.

FIG. 4B depicts a cross-sectional area of a soft metal heat port and base plate after stamping.

DETAILED DESCRIPTION OF THE INVENTION The insertion of heat ports into stamped base plates or tubs to form a hermetic seal is accomplished through a stamping process. The heat ports are manufactured from materials with good heat dissipation qualities, such as copper, molybdenum, copper-tungsten, copper-molybdenum, etc. The materials used for the bases or tubs include kovar, CRS, nickel-iron alloys, etc. Normally, the selection of one of these materials is made to control the thermal expansion of the plate. FIG. 1 depicts an exemplary heat dissipative plug, while FIG. 2 depicts an exemplary mating electronic enclosure into which the plug of FIG. 1 is stamped.

The inventors have developed a process for use with hard materials, such as molybdenum, copper-tungsten, and copper-molybdenum, that employs a locking system. FIGS. 3A and 3B illustrates the manner in which the mating materials are combined.

The heat port 1 is manufactured through a machining or molding process and is electroless nickel-plated. The base 2 is either stamped or machined and left unplated. The port 1 and base 2 are combined in a simple coining process where the heat port 1 is forced into the counterbored base hole 3. The heat port flange 4 coins the material from the softer base by the counterbore area 5 and the base material is forced into the recessed locking area 6 of the heat port. The newly attached pieces are now sent through a furnace to melt the plating to further fuse the materials together. After this process, the base is ground to assure flatness. The final product is shown in FIG. 3B.

With copper and softer, more malleable heat port materials, the heat ports and base plates are designed as illustrated in FIGS. 4A and 4B. As can be seen, the heat port 10 is smaller in diameter than the hole 12 in the base plate 11 but greater in height than the base plate 11. The heat port 10 is once again electroless nickel- plated. The heat port 10 is placed in the hole 12 in the base plate 11 and coined.

Upon coining the heat port 10, the heat port 10 becomes smaller in height and larger in diameter. The heat port 10 eventually locks tightly into the hole 12 in the base 11, as shown in FIG. 4B. The combined unit is then passed through a furnace to melt the electroless nickel plating, which helps fuse the materials together.

An advantage of this invention is that the manufacture of base plates for the microelectronics industry is much more cost effective than in the past. Presently, where controlling thermal expansion rates and heat dissipation are important factors in the design of an electronic package, base plates are made of molybdenum, copper- molybdenum, or copper-tungsten. These materials are all very difficult or impossible to stamp. They are all powdered materials that are very expensive. The process of the present invention allows the use of inexpensive and easy to stamp materials for the base and either inexpensive copper for the heat ports, or a much lesser amount of expensive material if the heat port selection is copper-tungsten, copper-molybdenum, or molybdenum. The optimal heat port material for use with the process of the invention is copper. Copper is the most manufacturable of all heat port materials and the least expensive. The process of the invention can provide heat

dissipation characteristics superior to molybdenum, copper-tungsten, and copper- molybdenum, while also controlling the thermal expansion of the plates through proper volume design and placement of the heat port within the base plate.

While the present invention has been described and illustrated in various preferred and alternate embodiments, such descriptions and illustrations are not to be construed to be limitations thereof. Accordingly, the present invention encompasses any variations, modifications and/or alternate embodiments with the scope of the present invention being limited only by the claims which follow.