Thermally conductive, electrically insulating connection

• US 5,948,521 A
• Filed: 08/07/1996
• Issued: 09/07/1999
• Est. Priority Date: 08/11/1995
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Gunzelmann, Karl-Heinz, Dlugosch, Dieter, Ideler, Karl-Heinz
• Primary Examiner(s): Thibodeau, Paul
• Assistant Examiner(s): Rickman, Holly C.
• Application Number:
  US08/692,237
• Time in Patent Office: 1,126 Days
• Field of Search: 428/307.3, 428/312.8, 428/317.1, 428/317.3, 428/319.3, 428/307.7, 428/319.1, 428/414, 427/294, 427/419.1, 427/419.2, 427/419.5, 427/427, 427/453, 427/446, 427/443.2, 156/60, 156/182, 156/330
• US Class Current: 428/307.3
• CPC Class Codes: B21D 39/00 Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating joining mitred profiles B21D53/745; riveting B21J; uniting components by forging or pressing to form integral members B21K25/00; welding B23K; press-fitting, force-fitting, or shrinking in general B23P11/00, B21D19/00; by adhesives F16B11/00 ; Connections as such F16L, F16B; Tube expanders
• CPC Class Codes: C04B 2111/00612 as one or more layers of a layered structure
• CPC Class Codes: C04B 2111/92 Electrically insulating materials
• CPC Class Codes: C04B 35/00 Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4523 applied from the molten state vitreous materials C04B41/5022; Thermal spraying, e.g. plasma spraying
• CPC Class Codes: C04B 41/4853 Epoxides
• CPC Class Codes: C04B 41/5022 with vitreous materials composition of vitreous glazes and enamels C03C; ceramic pigments C09C1/0009
• CPC Class Codes: C04B 41/5031 Alumina
• CPC Class Codes: C04B 41/52 Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/522 Multiple coatings, for one of the coatings of which at least one alternative is described
• CPC Class Codes: C04B 41/89 for obtaining at least two superposed coatings having different compositions
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/3735 Laminates or multilayers, e.g. direct bond copper ceramic substrates
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/249956 Void-containing component is inorganic
• CPC Class Codes: Y10T 428/249957 Inorganic impregnant
• CPC Class Codes: Y10T 428/24997 Of metal-containing material
• CPC Class Codes: Y10T 428/249982 With component specified as adhesive or bonding agent
• CPC Class Codes: Y10T 428/249983 : As outermost component
• CPC Class Codes: Y10T 428/24999 : Inorganic
• CPC Class Codes: Y10T 428/249991 : Synthetic resin or natural rubbers
• CPC Class Codes: Y10T 428/31515 : As intermediate layer

Abstract

A thermally conductive, electrically insulating connection, which is not sensitive to air moisture comprises a ceramic layer formed by thermal spraying on a surface of the workpiece, which layer is either impregnated or sealed with electrically insulating material and is joined to another workpiece which may be a ceramic layer which has been either impregnated or sealed and attached to another member. The connection is particularly useful in power assemblies with at least one power component for conducting away lost heat from the component with a sufficient electrical insulation of the component from the cooling body or heat sink.

Claims

1. A thermally conductive, electrically insulating connection between two workpieces, said connection comprising a ceramic layer being attached to at least one workpiece surface, said layer being a thermally sprayed layer and having means for preventing any hygroscopicity in the layer, said means comprising all outer surfaces of the layer being sealed with an electrically insulating material to form sealed surfaces, one of said sealed surfaces of the ceramic layer being connected by a layer of adhesive with a facing surface of the other workpiece of the two workpieces.

2. A thermally conductive, electrically insulating connection according to claim 1, wherein the ceramic layer is an oxide ceramic.

3. A thermally conductive, electrically insulating connection according to claim 2, wherein the oxide ceramic is aluminum oxide.

4. A thermally conductive, electrically insulating connection according to claim 1, wherein the ceramic layer is sealed with a material selected from a group consisting of resin and adhesive.

5. A thermally conductive, electrically insulating connection according to claim 4, wherein the resin is an epoxy resin.

6. A thermally conductive, electrically insulating connection according to claim 1, wherein the ceramic layer is sealed with a ceramic glaze having a melting point in a range of between 600°

and 800°

C.

7. A thermally conductive, electrically insulating connection according to claim 1, wherein the adhesive layer is an epoxy layer.

8. A thermally conductive, electrically insulating connection according to claim 1, wherein the adhesive layer is mixed with a thermally conductive powder.

9. A thermally conductive, electrically insulating connection according to claim 1, wherein the facing surface of the other workpiece is a sealed surface, which is sealed with an electrically insulating material, of a ceramic layer which is attached to the other workpiece.

10. A thermally conductive, electrically insulating connection according to claim 9 wherein both ceramic layers are completely impregnated with the electrically insulating material.

11. A thermally conductive, electrically insulating connection according to claim 1 wherein the ceramic layer is completely impregnated with the electrically insulating material.

12. A method for manufacturing a thermally conductive electrically insulating connection between two workpieces comprising the steps of thermally spraying a ceramic layer on a surface of one workpiece, forming means for preventing any hygroscopicity in the ceramic layer by sealing all outer surfaces of the ceramic layer with an electrically insulating material, and then connecting one of the outer surfaces of the sealed ceramic layer to another workpiece surface by providing an adhesive layer between the one outer surface and said another workpiece surface.

13. A method according to claim 12, wherein the step of thermally spraying comprises plasma spraying the ceramic layer onto the workpiece.

14. A method according to claim 12, the step of sealing utilizes a low pressure impregnation of the ceramic layer with a material selected from a resin and an adhesive.

15. A method according to claim 14, wherein the step of sealing by a low pressure impregnation utilizes a vacuum impregnation of the ceramic layer with an epoxy resin.

16. A method according to claim 12 wherein the step of providing an adhesive layer provides an epoxy resin.

17. A method according to claim 12, which includes mixing a thermally conductive powder in the adhesive layer.

18. A thermally conductive, electrically insulating connection between elements including a heat spreading element and a heat sink, said connection comprising a ceramic layer being attached to a surface of one of the two elements, said ceramic layer being a thermally sprayed layer and having means for preventing any hygroscopicity in the sprayed layer, said means comprising all outer surfaces of the sprayed layer being impregnated with an electrically insulating material to form sealed surfaces, one of said sealed surfaces of the ceramic layer being connected by an adhesive layer with a surface of the other element of the two elements.