US5596231A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High power dissipation plastic encapsulated package for integrated circuit die
Assignee: UTAC Hong Kong Ltd
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Filing: 1994-11-30
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Granted: 1997-01-21
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Expires: 2014-11-30
Abstract
Abstract A structure and a method provide an assembly for receiving an integrated circuit die. The assembly comprises a heat sink selectively coated with electrically insulative material. The heat sink is attached by one of various methods directly on to the integrated circuit die and a lead frame for external electrical connections. The heat sink is formed as a stepped structure to increase the path of moisture penetration so as to improve moisture resistance and reliability. In one embodiment of the present invention, the electrically insulative material comprises anodized aluminum, which is formed on the heat sink by a vapor deposition step, followed by a hard anodization step. Other electrical insulative material which can be thinly applied on the surface of the heat sink are non-conductive resins and polymers. The heat sink is formed out of copper or a copper alloy, selected for strength and electrical and thermal conductivities. The heat sink can be connected to a power or a ground terminal of the integrated circuit, which is bonded on the heat sink on an exposed (i.e. unaluminized) exposed area of the heat sink. The exposed area of the heat sink is formed either by a step which masked off the exposed area from the aluminum deposition step, or by a subtractive process, such as sand-blasting, to selectively removing the anodized aluminum. In one embodiment, the assembly is encapsulated in plastic with one side of the heat sink flush with one outer surface of the plastic encapsulation.
Inventors
- 👤 Edward G. Combs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:01
CPC Classifications
H; H10; H10W; H10W40/00; H10W40/70; H10W40/77; H10W40/778; H10W74/00; H10W90/00; H10W90/701; H10W90/751; H10W90/756
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
165 words
An assembly comprising: a lead frame; a heat sink composed of a thermally conductive material, said heat sink including a stepped structure having a base and a protrusion from said base; a layer, having a predetermined thickness, of thermally conductive and electrically insulative material selectively provided on a surface of said base of said stepped structure opposite said lead frame and away from said protrusion for electrically insulating said heat sink from selected portions of said lead frame; and a resinous encapsulation for said lead frame and said heat sink, said resinous encapsulation interlocking the stepped structure of said heat sink, thereby minimizing displacement of said heat sink within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 2
Dependent Claim
165 words
An assembly comprising: a lead frame; a heat sink composed of a thermally conductive material, said heat sink including a stepped structure having a base and a protrusion from said base; a layer, having a predetermined thickness, of thermally conductive and electrically insulative material selectively provided on a surface of said base of said stepped structure opposite said lead frame and away from said protrusion for electrically insulating said heat sink from selected portions of said lead frame; and a resinous encapsulation for said lead frame and said heat sink, said resinous encapsulation interlocking the stepped structure of said heat sink, thereby minimizing displacement of said heat sink within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 3
Dependent Claim
30 words
An assembly as in claim 1, wherein said layer of thermally conductive and electrically insulative material is selected from a group consisting of anodized aluminum, non-conductive resins and non-conductive polymers.
Claim 4
Dependent Claim
24 words
An assembly as in claim 1, wherein said resinous encapsulation encapsulates said assembly in plastic, said resinous encapsulation being formed by a molding step.
Claim 5
Dependent Claim
138 words
An integrated circuit assembly, comprising: a block of thermally conductive material having a thin surface layer of an electrically insulative material of a predetermined thickness, said block including a stepped structure having a base and a protrusion from said base; a lead frame attached to a surface of said base of said stepped structure; and a resinous encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 6
Dependent Claim
138 words
An integrated circuit assembly, comprising: a block of thermally conductive material having a thin surface layer of an electrically insulative material of a predetermined thickness, said block including a stepped structure having a base and a protrusion from said base; a lead frame attached to a surface of said base of said stepped structure; and a resinous encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 7
Dependent Claim
14 words
An assembly as in claim 4, wherein said thin surface layer comprises anodized aluminum.
Claim 8
Dependent Claim
16 words
An assembly as in claim 4, wherein said thin surface layer comprises an electrically non-conductive polymer.
Claim 9
Dependent Claim
16 words
An assembly as in claim 4, wherein said thin surface layer comprises an electrically non-conductive resin.
Claim 10
Dependent Claim
41 words
An assembly as in claim 4, wherein: said block is electrically conductive; and said electrically insulative material is absent at selected sites for lead frame attachment, said lead frame having support members attached at said sites in an electrically conductive manner.
Claim 11
Dependent Claim
25 words
An assembly as in claim 8, wherein said electrically conductive manner is selected from the group consisting of welded, soldered, conductively glued or eutectically bonded.
Claim 12
Dependent Claim
24 words
An assembly as in claim 9, wherein said support members are each a vestige of a tie bar severed at a die attach area.
Claim 13
Dependent Claim
159 words
An integrated circuit assembly, comprising: a block of electrically and thermally conductive material forming a heat sink, said block including a stepped structure having a base and a protrusion from said base; a thin layer of anodized aluminum selectively formed on a surface of said base of said stepped structure; a lead frame attached to said heat sink, such that said thin layer of anodized aluminum selectively insulating said lead frame from said heat sink; and a resin encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 14
Dependent Claim
159 words
An integrated circuit assembly, comprising: a block of electrically and thermally conductive material forming a heat sink, said block including a stepped structure having a base and a protrusion from said base; a thin layer of anodized aluminum selectively formed on a surface of said base of said stepped structure; a lead frame attached to said heat sink, such that said thin layer of anodized aluminum selectively insulating said lead frame from said heat sink; and a resin encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 15
Dependent Claim
24 words
An assembly as in claim 11, wherein said electrically and thermally conductive material is selected from the group consisting of copper and copper alloys.
Claim 16
Dependent Claim
20 words
An assembly as in claim 11, further comprising a thin layer of nickel between said anodized aluminum and said block.
Claim 17
Dependent Claim
41 words
An assembly as in claim 13, further comprising: an integrated circuit die attached to said heat sink; and wherein said resinous encapsulation encapsulates said assembly such that a surface of said block is flush with a surface of said resinous encapsulation.
Claim 18
Dependent Claim
160 words
An integrated circuit assembly, comprising: a block of thermally and electrically conductive material, including steel, forming a heat sink, said heat sink including a stepped structure having a base and a protrusion from said base; a layer of electrically insulative porcelain selectively provided on a surface of said base of said stepped structure; a lead frame attached to said block, such that said layer of electrically insulative porcelain selectively insulating said block from said lead frame; and a resinous encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 19
Dependent Claim
160 words
An integrated circuit assembly, comprising: a block of thermally and electrically conductive material, including steel, forming a heat sink, said heat sink including a stepped structure having a base and a protrusion from said base; a layer of electrically insulative porcelain selectively provided on a surface of said base of said stepped structure; a lead frame attached to said block, such that said layer of electrically insulative porcelain selectively insulating said block from said lead frame; and a resinous encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 20
Dependent Claim
156 words
An integrated circuit assembly, comprising: a block of thermally and electrically conductive material forming a heat sink, said heat sink including a stepped structure having a base and a protrusion from said base; a layer of fired glass selectively provided on a surface of said base of said stepped structure; a lead frame attached to said block, such that said layer of fired glass selectively insulating said block from said lead frame; and a resinous encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 21
Dependent Claim
156 words
An integrated circuit assembly, comprising: a block of thermally and electrically conductive material forming a heat sink, said heat sink including a stepped structure having a base and a protrusion from said base; a layer of fired glass selectively provided on a surface of said base of said stepped structure; a lead frame attached to said block, such that said layer of fired glass selectively insulating said block from said lead frame; and a resinous encapsulation for said block and said lead frame, said resinous encapsulation interlocking the stepped structure of said block, thereby minimizing displacement of said block within said resinous encapsulation, said resinous encapsulation positioning a surface of said protrusion of said stepped structure on an opposite side of said surface of said base of said stepped structure, so as to transfer heat generated at said lead frame out of said integrated circuit assembly through said surface of said protrusion of said stepped structure.
Claim 22
Dependent Claim
97 words
A heat sink comprising: a first portion having a first surface for attaching thereon an integrated circuit die; and a second portion protruding from said first portion in a direction away from said first surface thereby forming a stepped structure between said first and second portions, said second portion having a second surface opposite said first surface, said second surface conducting heat generated at said integrated circuit die out of said heat sink, wherein exposed surfaces of said first and second portions are provided a layer of thermally conductive and electrically insulative material except at selected areas.
Claim 23
Dependent Claim
97 words
A heat sink comprising: a first portion having a first surface for attaching thereon an integrated circuit die; and a second portion protruding from said first portion in a direction away from said first surface thereby forming a stepped structure between said first and second portions, said second portion having a second surface opposite said first surface, said second surface conducting heat generated at said integrated circuit die out of said heat sink, wherein exposed surfaces of said first and second portions are provided a layer of thermally conductive and electrically insulative material except at selected areas.
Claim 24
Dependent Claim
142 words
An assembly comprising: a lead frame; a heat sink composed of a thermally conductive material, said heat sink including a stepped structure having a base and a protrusion from said base, so as to have a top surface on said protrusion and a bottom surface on said base, said top surface being substantially parallel to and smaller in size than said bottom surface; a layer, having a predetermined thickness, of thermally conductive and electrically insulative material selectively provided on said bottom surface of said heat sink for electrically insulating said heat sink from selected portions of said lead frame; and a resinous encapsulation for said lead frame and said heat sink, said resinous encapsulation interlocking said stepped structure so as to secure said heat sink in said resinous encapsulation while exposing said top surface flush with a surface of said resinous encapsulation.
Claim 25
Dependent Claim
142 words
An assembly comprising: a lead frame; a heat sink composed of a thermally conductive material, said heat sink including a stepped structure having a base and a protrusion from said base, so as to have a top surface on said protrusion and a bottom surface on said base, said top surface being substantially parallel to and smaller in size than said bottom surface; a layer, having a predetermined thickness, of thermally conductive and electrically insulative material selectively provided on said bottom surface of said heat sink for electrically insulating said heat sink from selected portions of said lead frame; and a resinous encapsulation for said lead frame and said heat sink, said resinous encapsulation interlocking said stepped structure so as to secure said heat sink in said resinous encapsulation while exposing said top surface flush with a surface of said resinous encapsulation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-01-21 | 2000-07-22 | 2001-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-21 | 2004-07-22 | 2005-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-21 | 2008-07-22 | 2009-01-21 | $7700.00 | Window Closed / Lapsed |