Method for producing metal/ceramic bonding substrate

Abstract

After a molten metal of aluminum or an aluminum alloy having a temperature, which is higher than the liquidus line temperature of aluminum or the aluminum alloy by 5 to 200° C., is injected into a mold, when the mold is cooled to solidify the molten metal, the molten metal injected into the mold is pressurized at a pressure of 1.0 to 100 kPa from a high-temperature side to a low-temperature side, and the mean cooling rate is set to be 5 to 100° C./minute while the mold is cooled from the liquidus line temperature to 450° C., the temperature gradient formed in the mold being set to be in the range of from 1° C./cm to 50° C./cm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the preferred embodiments of the invention. However, the drawings are not intended to imply limitation of the invention to a specific embodiment, but are for explanation and understanding only.

In the drawings:

FIG. 1 is a plan view of a metal/ceramic circuit board produced in examples and comparative examples;

FIG. 2 is a sectional view taken along line II-II of FIG. 1; and

FIG. 3 is a sectional view of a mold used in the preferred embodiment of a method for producing a metal/ceramic bonding substrate according to the present invention.

Claims

1. A method for producing a metal/ceramic bonding substrate, the method comprising the steps of: setting a ceramic substrate in a mold having an inlet;injecting a molten metal of aluminum or an aluminum alloy into the mold from the inlet so as to allow the molten metal to contact the ceramic substrate; andsolidifying the molten metal to bond a metal member of aluminum or the aluminum alloy to the ceramic substrate by cooling the mold while pressurizing the molten metal injected into the mold.

2. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal is solidified by cooling a part of the mold to form a high-temperature side and a low-temperature side in the mold and by cooling the mold while the molten metal injected into the mold is pressurized from the high-temperature side to the low-temperature side.

3. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal is solidified by cooling the mold so that the inlet side in the mold is a high-temperature side and the opposite side in the mold to the inlet is a low-temperature side, the temperature on which is lower than that on the high-temperature side, and by cooling the mold while the molten metal injected into the mold is pressurized from the high-temperature side to the low-temperature side.

4. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal is pressurized at a pressure of 1.0 to 100 kPa when the mold is cooled.

5. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal injected into the mold has a temperature which is higher than the liquidus line temperature of the molten metal by 5 to 200° C.

6. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal is cooled at a mean cooling rate of 5 to 100° C./minute while being cooled from the liquidus line temperature of the molten metal to 450° C.

7. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein a temperature gradient of 1 to 50° C./cm is formed in the mold when the mold is cooled.

8. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, which further comprising a step of heating the mold so that the difference between the temperature of the mold and the temperature of the molten metal is not higher than 250° C., before injecting the molten metal into the mold.

9. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal is pressurized from the inlet.

10. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein the molten metal is pressurized from an opening formed in the mold.

11. A method for producing a metal/ceramic bonding substrate as set forth in claim 1, wherein said aluminum alloy contains silicon.