Multi-layer heat sinking integrated circuit package

Claim 1

A heat-sinking package for an integrated circuit die having a series of electrical contact pads extending around a periphery of a top surface of the die comprising: a thermally conductive base having a top die-attach surface; means having a high degree of thermal conductivity for bonding a bottom surface of said die to a finite area of said die-attach surface; an electrically-insulating preform spacedly surrounding said finite area and having a bottom surface bonded to said base; a metallic lead-frame mounted on said preform and including spaced multiple fingers each having inner ends spacedly juxtaposed to said die contact pads and outer connector ends extending exterior of said preform; means for wire bonding various of said die contact pads to said lead-frame inner ends; and insulative cover means for covering said die-attach surface and die and having edges bonded to portions of said lead-frame between said lead-frame inner ends and outer ends and to said preform through openings between said spaced lead-frame fingers. 2. The package of Claim 1 in which said conductive base comprises a material having a coefficient of thermal conductivity of at least 0.25 calories per sec. per cm per °C. 3. The package of Claim 2 in which said conductive base comprises copper. 4. The package of Claim 2 in which said conductive base comprises aluminum. 5. The package of Claim 1 in which said die is bonded to said die-attach surface by an electrically- conductive adhesive. 6. The package of Claim 5 in which said adhesive comprises silver-filled glass epoxy resin. 7. The package of Claim 1 wherein said base, said preform, said lead-frame and said cap form a dual-in-line package. 8. The package of Claim 1 wherein said cap includes castellated peripheral top portions and said outer connector ends extending between said castellations. 9. The package of Claim 1 wherein said base, said preform and said cap are peripherally symmetrical in plan view. 10. The package of Claim 1 wherein said base has a flat overall surface including said die-attach surface. 11. The package of Claim 1 wherein said preform and said lead-frame has a collective thickness conforming to the height of said die whereby the top of said lead-frame inner legs are in the same horizontal plane as said die contact pads. 12. The package of Claim 1 wherein said base, when assembled on a printed circuit board, has its exterior bottom surface completely exposed to ambient.