# US 6,294,244 B1 · Wiring board having excellent heat-radiating property

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- Number: US 6,294,244 B1
- Document ID: US6294244B1
- Status: Granted
- Kind: B1
- Application number: 09/217,087
- Filed: 1998-12-21
- Granted: 2001-09-25
- Earliest claimed: 1997-12-22
- Assignees: KYOCERA Corporation
- Inventors: Toshihiro Iwaida; Teruhisa Makino; Masanobu Ishida; Tomohide Hasegawa; Hirosi Okayama
- Web page: https://patentgrep.com/patent/US6294244B1

## CPC

- H10W 70/692: Ceramics or glasses
- C04B 35/584: based on silicon nitride
- H10W 40/10: Arrangements for heating
- H05K 1/0306: {Inorganic insulating substrates, e.g. ceramic, glass}
- H10W 72/075: {of bond wires}
- H10W 72/5363: {the connected ends being wedge-shaped}
- H10W 72/5524: {comprising aluminium [Al]}
- H10W 72/884: {Die-attach connectors and bond wires}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- H10W 74/00: Encapsulations, e.g. protective coatings
- H10W 90/734: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W 90/754: {between a chip and a stacked insulating package substrate, interposer or RDL}
- Y10S 428/901: Printed circuit
- Y10T 428/24917: including metal layer
- Y10T 428/266: of base or substrate
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A wiring board of the present invention is equipped with an insulating board formed of a sintered product of silicon nitride containing a silicon nitride crystal phase, and a metal circuit formed on said insulating board, wherein said sintered product of silicon nitride contains a rare earth element (RE) and magnesium in a total amount of from 4 to 30 mol % calculated as oxides and at a molar ratio (RE2O3/MgO) calculated as oxides of from 0.1 to 15, and has a relative density of not smaller than 90% and a heat conductivity of not smaller than 50 W/m·K. The wiring board is equipped with the insulating board having very excellent heat-radiating property and a large strength, and is very useful as a wiring board for, for example, power modules.

## Claims

### Claim 1

A wiring board equipped with an insulating board formed of a sintered product of silicon nitride containing a silicon nitride crystal phase, and a metal circuit formed on said insulating board, wherein said sintered product of silicon nitride contains a rare earth element (RE) and magnesium in a total amount of from 4 to 30 mol % calculated as oxides and at a molar ratio (RE2O3/MgO) calculated as oxides of from 0.1 to 15, and has a relative density of not smaller than 90% and a heat conductivity of not smaller than 50 W/m·K.

### Claim 2 (depends on 1)

A wiring board according to claim 1, wherein said sintered product of silicon nitride contains aluminum in an amount of not larger than 1.0 mol % calculated as an oxide.

### Claim 3 (depends on 1)

A wiring board according to claim 1, wherein said sintered product of silicon nitride contains a crystal phase of MgSiO3 or MgSiN2 in the grain boundary phase of silicon nitride crystal phase.

### Claim 4 (depends on 1)

A wiring board according to claim 1, wherein said crystals of silicon nitride contained in said sintered product of silicon nitride are columnar crystals having an average long-axis diameter of from 0.5 to 3 μm.

### Claim 5 (depends on 1)

A wiring board according to claim 1, wherein said insulating board has a Young's modulus of not larger than 300 GPa at room temperature.

### Claim 6 (depends on 1)

A wiring board according to claim 1, which is used for a power module.

### Claim 7 (depends on 6)

A wiring board according to claim 6, wherein said insulating board has a thickness of not larger than 1 mm, and a power element connected to said metal circuit is mounted on the surface of said insulating board.

### Claim 8 (depends on 7)

A wiring board according to claim 7, wherein said metal circuit has a thickness of not smaller than 0.1 mm.

### Claim 9 (depends on 7)

A wiring board according to claim 7, wherein said metal circuit is joined to the surface of the insulating board by using an active metal.

### Claim 10

A wiring board equipped with an insulating board formed of a sintered product of silicon nitride containing a silicon nitride crystal phase fired at a temperature less than 1800° C., and a metal circuit formed on said insulating board, wherein said sintered product of silicon nitride contains a rare earth element (RE) and magnesium in a total amount of from 4 to 30 mol % calculated as oxides and at a molar ratio (RE2O3/MgO) calculated as oxides of from 0.1 to 15, has a relative density of not smaller than 90%, and a heat conductivity of not smaller than 50 W/m·K.

### Claim 11

A wiring board equipped with an insulating board formed of a sintered product of silicon nitride containing a silicon nitride crystal phase and a metal circuit formed on said insulating board, wherein said sintered product of silicon nitride contains a rare earth element (RE) and magnesium in a total amount of from 4 to 30 mol % calculated as oxides at a molar ratio (RE2O3/MgO) calculated as oxides of from 0.1 to 15, has a relative density of not smaller than 90%, and a heat conductivity of not smaller than 50 W/m·K, and wherein said crystals of silicon nitride are columnar with an average long-axis diameter of from 0.5 to 3 μm.