Functionally gradient circuit board

• US 5,294,477 A
• Filed: 11/22/1991
• Issued: 03/15/1994
• Est. Priority Date: 11/30/1990
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Takagi, Hiroshi, Wada, Nobuyuki, Sano, Harunobu, Kanba, Seiji
• Primary Examiner(s): Ryan, Patrick J.
• Assistant Examiner(s): LAM, CATHY FONG FONG
• Application Number:
  US07/796,309
• Time in Patent Office: 844 Days
• Field of Search: 428/209, 428/210, 428/212, 428/901, 428/325, 428/328, 428/217, 428/446, 428/450, 428/472, 29/182.2, 29/182.3, 29/182.5
• US Class Current: 428/212
• CPC Class Codes: H01L 23/142 Metallic substrates having insulating layers
• CPC Class Codes: H01L 23/3733 having a heterogeneous or anisotropic structure, e.g. powder or fibres in a matrix, wire mesh, porous structures H01L23/3732, H01L23/3737 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H05K 1/03 Use of materials for the substrate
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 2201/0215 Metallic fillers
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24983 Hardness
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof

Abstract

A functionally gradient circuit board is constituted by a mixture of a metal and an insulating ceramic composition, the abundance ratio of the metal component to the component of the insulating ceramic composition being changed in the direction of thickness of the board.

Claims

1. A functionally gradient circuit board having electrical and thermal insulation properties that change as a function of position in the direction of thickness of the board, the circuit board comprising a mixture of a metal and an electrically insulating ceramic compound having a coefficient of thermal conductivity lower than said metal, wherein said mixture of said metal and said electrically insulating ceramic compound contains said metal and said electrically insulating ceramic compound in a ratio that changes in the direction of thickness of the board so that the electrical and thermal insulation properties of said circuit board correspondingly change as a function of position in the direction of the thickness of the board.

2. The functionally gradient circuit board according to claim 1, wherein said ratio of said metal to said electrically insulating ceramic compound changes substantially continuously in the direction of thickness of the board.

3. The functionally gradient circuit board accordingly to claim 1, wherein the coefficient of thermal conductivity of said circuit board changes as a function of position in the direction of the thickness of the board.

4. The functionally gradient circuit board according to claim 1, wherein said circuit board comprises a plurality of layers, the layers being laminated in the thickness direction of the circuit board, each layer having said metal and said electrically insulating ceramic compound in a ratio which is different from the ratio of the metal and ceramic compound in an adjacent layer.

5. The functionally gradient circuit board according to claim 1, where said electrically insulating ceramic compound is alumina.

6. The functionally gradient circuit board according to claim 1, wherein said metal is silver.

7. The functionally gradient circuit board according to claim 1, wherein the coefficient of thermal expansion of said circuit board changes as a function of position in the direction of the thickness of the board.

8. The functionally gradient circuit board according to claim 7, wherein the coefficient of thermal expansion of said circuit board continuously changes in the direction of the thickness of the board.

9. The functionally gradient circuit board according to claim 1, wherein the electrical insulation property of said circuit board continuously changes in the direction of the thickness of the board.

10. The functionally gradient circuit board according to claim 1, wherein the coefficient of thermal conductivity of said circuit board continuously changes in the direction of the thickness of the board.

11. The functionally gradient circuit board according to claim 1, wherein the electrical insulation property, the coefficient of thermal expansion and the coefficient of thermal conductivity of said circuit board change as a function of position in the direction of the thickness of the board.

12. A functionally gradient circuit board having electrical and thermal insulation properties that change as a function of position in the direction of thickness of the board, the circuit board comprising a mixture of a metal and an electrically insulating ceramic compound having a coefficient of thermal conductivity lower than said metal, wherein said mixture of said metal and said electrically insulating ceramic compound contains said metal and said electrically insulating ceramic compound in a ratio that changes in the direction of thickness of the board so that the electrical resistance property, the coefficient of thermal expansion and the coefficient of thermal conductivity of said circuit board correspondingly change as a function of position in the direction of the thickness of the board.

13. The functionally gradient circuit board according to claim 12, wherein the coefficient of thermal conductivity of said circuit board continuously changes in the direction of the thickness of the board.

14. The functionally gradient circuit board according to claim 12, wherein the electrical insulation property of said circuit board continuously changes in the direction of the thickness of the board.

15. The functionally gradient circuit board according to claim 12, wherein the coefficient of thermal expansion of said circuit board continuously changes in the direction of the thickness of the board.