Metal-ceramic bonding substrate and method for manufacturing the same

Abstract

The present invention provides a metal-ceramic bonded substrate and a manufacturing method thereof, wherein the bonding strength of an aluminum plate directly bonded to a ceramic substrate is higher than that of the conventional one. A ceramic substrate 10 is arranged in a casting mold 20, and the casting mold 20 is placed in a furnace, wherein the oxygen concentration in the furnace is reduced to below 25 ppm and the dew point is reduced to below -45°C, and aluminum melt is injected in a manner that contacts the surface of the ceramic substrate 10, and then the melt is cooled to solidify, thereby forming a metal plate 14 for a circuit pattern formed of aluminum on one side of the ceramic substrate 10 so that one side of the metal plate 14 for the circuit pattern is directly bonded to the ceramic substrate 10, and at the same time, a metal substrate 12 formed of aluminum is formed on the other side of the ceramic substrate 10 so that it is directly bonded to the ceramic substrate 10, thereby obtaining a metal-ceramic bonded substrate.

Description

Technical Field

[0001] The present invention relates to a metal-ceramic bonding substrate and a method for manufacturing the same, and in particular to a metal-ceramic bonding substrate in which an aluminum plate is bonded to an aluminum nitride substrate and a method for manufacturing the same. Background Art

[0002] Conventionally, in power modules used to control large currents in electric vehicles, trams, machine tools, etc., a metal-ceramic insulating substrate is fixed to one side of a metal substrate by welding, and a semiconductor chip is fixed to the metal-ceramic insulating substrate by welding. In addition, a metal heat sink or cooling sleeve is installed on the other side (inner side) of the metal substrate by tightening screws, etc., with thermally conductive grease.

[0003] Since the welding of the metal substrate or semiconductor chip to the metal-ceramic insulating substrate is carried out by heating, the difference in thermal expansion coefficients between the joining components during welding can easily cause the metal substrate to warp. In addition, if the heat generated by the semiconductor chip escapes to the air or cooling water through the metal-ceramic insulating substrate, solder and substrate through the heat sink or cooling sleeve, causing the metal substrate to warp during welding, the gap when the heat sink or cooling sleeve is installed on the metal substrate becomes larger, and the heat dissipation is extremely reduced. In addition, since the thermal conductivity of solder itself is low, power modules that flow large currents are required to have higher heat dissipation.

[0004] In order to solve these problems, a metal-ceramic bonded substrate has been proposed in which an aluminum plate is directly bonded to a ceramic substrate such as an aluminum nitride substrate, instead of welding the metal substrate and the metal-ceramic insulating substrate (for example, see Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-144224 (Paragraph Nos. 0016-0017) Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] However, in the metal-ceramic bonded substrate of Patent Document 1, the peel strength between the aluminum plate and the ceramic substrate is about 30 kg / cm, and in recent years, a metal-ceramic bonded substrate having a higher bonding strength has been desired.

[0010] Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a metal-ceramic bonded substrate in which the bonding strength of an aluminum plate directly bonded to a ceramic substrate is higher than that of the related art, and a method for manufacturing the same.

[0011] Technical solutions adopted to solve technical problems

[0012] The inventors of the present invention have conducted intensive research to solve the above-mentioned problems, and as a result, have found that by placing a ceramic substrate in a casting mold, placing the casting mold in a furnace, reducing the oxygen concentration in the furnace to below 25 ppm and the dew point to below -45°C, injecting molten aluminum in a manner that contacts one side of the ceramic substrate and then cooling the molten aluminum to solidify it, an aluminum plate is formed on one side of the ceramic substrate and the aluminum plate is directly bonded to the ceramic substrate, thereby achieving an aluminum plate directly bonded to the ceramic substrate with a higher bonding strength than conventional metal-ceramic bonded substrates, thereby completing the present invention.

[0013] That is, the manufacturing method of the metal-ceramic joint substrate of the present invention is characterized in that a ceramic substrate is arranged in a casting mold, the casting mold is placed in a furnace, the oxygen concentration in the furnace is reduced to below 25 ppm and the dew point is reduced to below -45°C, molten aluminum is injected in a manner that contacts one side of the ceramic substrate, and then the molten aluminum is cooled to solidify, thereby forming an aluminum plate on one side of the ceramic substrate and directly bonding the aluminum plate to the ceramic substrate.

[0014] In the method for manufacturing the metal-ceramic bonded substrate, the aluminum plate is preferably an aluminum plate for a circuit pattern. In addition, when the aluminum melt is injected in a manner that contacts one side of the ceramic substrate in the mold, it is preferred that the aluminum melt is injected in a manner that contacts the other side of the ceramic substrate in the mold, and an aluminum substrate is formed on the other side of the ceramic substrate so that the aluminum substrate and the ceramic substrate are directly bonded. In addition, the ceramic substrate is preferably an aluminum nitride substrate, and the aluminum is aluminum with a purity of 99.9% by mass or more. In addition, it is preferred that the injection of the molten liquid and the cooling are performed while pressurizing.

[0015] The metal-ceramic bonding substrate of the present invention is characterized in that an aluminum plate formed by aluminum is directly bonded to one side of a ceramic substrate, the maximum thickness of the oxide layer formed at the bonding interface between the aluminum plate and the ceramic substrate is less than 4 nm, and the bonding strength between the aluminum plate and the ceramic substrate is greater than 330 N / cm.

[0016] In the metal-ceramic bonding substrate, the aluminum plate is preferably an aluminum plate for circuit patterns. In addition, the aluminum substrate formed of aluminum is preferably directly bonded to the other side of the ceramic substrate, the maximum thickness of the oxide layer formed at the bonding interface between the aluminum substrate and the ceramic substrate is less than 4nm, and the bonding strength between the aluminum substrate and the ceramic substrate is greater than 330N / cm. In addition, the maximum thickness of the oxide layer is preferably less than 3nm, and the bonding strength is greater than 350N / cm. In addition, the ceramic substrate is preferably an aluminum nitride substrate, and the aluminum is aluminum with a purity of more than 99.9% by mass.

[0017] Effects of the Invention

[0018] According to the present invention, the aluminum plate directly bonded to the ceramic substrate can have a higher bonding strength than the conventional metal-ceramic bonding substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A It is a top view of an embodiment of the metal-ceramic joint substrate of the present invention.

[0020] Figure 1B yes Figure 1A IB-IB line cross-sectional view of the metal-ceramic bonding substrate.

[0021] Figure 2A It is used to manufacture Figure 1A A cross-sectional view of a casting mold for a metal-ceramic bonding substrate.

[0022] Figure 2B yes Figure 2A A top view of the lower mold component of the mold.

[0023] Figure 3 is used for Figure 1A Schematic diagram of an apparatus for manufacturing a metal-ceramic bonded substrate. DETAILED DESCRIPTION

[0024] In an embodiment of the method for manufacturing a metal-ceramic bonded substrate of the present invention, a ceramic substrate (preferably formed of aluminum nitride, aluminum oxide, silicon nitride, etc.) is arranged in a casting mold, the casting mold is placed in a furnace, the oxygen concentration in the furnace is reduced to 25 ppm or less (preferably 15 ppm or less), and the dew point is reduced to -45°C or less (preferably -48°C or less), and molten aluminum (preferably having a purity of 99.9% by mass or more, more preferably having a purity of 99.99% by mass or more) is injected in a manner contacting the surface of the ceramic substrate (preferably while removing the oxide film and pressurizing the molten aluminum in the casting mold to about 5 to 15 kPa) is injected, and then the molten aluminum is cooled (preferably when nitrogen gas is introduced into the casting mold and the molten aluminum in the casting mold is pressurized to about 5 to 15 kPa) to solidify (solidify), thereby forming a metal plate for a circuit pattern formed of aluminum on one side of the ceramic substrate and directly bonding one side of the metal plate for the circuit pattern to the ceramic substrate, and simultaneously forming a metal substrate formed of aluminum on the other side of the ceramic substrate and directly bonding it to the ceramic substrate.

[0025] In addition, in an embodiment of the metal-ceramic bonding substrate of the present invention, Figure 1A to Figure 1BAs shown, one or more (one in the illustrated embodiment) metal substrates for circuit patterns (aluminum plates for circuit patterns) 14 formed of aluminum (preferably having a purity of 99.9 mass % or more, more preferably having a purity of 99.99 mass % or more) having a roughly rectangular planar shape is directly bonded to one side of a ceramic substrate 10 formed of aluminum nitride having a roughly rectangular planar shape, and a metal substrate (aluminum substrate) 12 formed of aluminum (preferably having a purity of 99.9 mass % or more, more preferably having a purity of 99.99 mass % or more) having a roughly rectangular planar shape is directly bonded to the other side (inner side) of the ceramic substrate 10, and the maximum thickness of an oxide layer (not shown) formed at the bonding interface between the ceramic substrate 10 and the metal plate for circuit patterns 14 and the bonding interface between the ceramic substrate 10 and the metal substrate 12 is 4 nm or less (preferably 3 nm or less), and the bonding strength between the ceramic substrate 10 and the metal plate for circuit patterns 14 (or between the ceramic substrate 10 and the metal substrate 12) is 330 N / cm or more (preferably 350 N / cm or more).

[0026] The embodiment of the metal-ceramic bonding substrate can be used, for example, Figure 2A to Figure 2B The casting mold 20 shown is manufactured by the embodiment of the above-mentioned method for manufacturing a metal-ceramic bonded substrate.

[0027] like Figure 2A As shown, the mold 20 is formed of a permeable material (impermeable to the molten liquid) such as (porous) carbon or porous metal, and is composed of a lower mold member 22 and an upper mold member 24 having a substantially rectangular planar shape. Figure 2A and Figure 2B As shown, a recess (metal substrate forming portion) 22a (for forming a metal substrate) for forming the metal substrate 12 is formed on the upper surface of the lower mold member 22. One or more (one in the illustrated embodiment) recesses (ceramic substrate receiving portion) 22b having substantially the same shape and size as the ceramic substrate 10 are formed in the approximate center of the bottom surface of the metal substrate forming portion 22a. One or more (one in the illustrated embodiment) recesses (circuit pattern forming portion) 22c (circuit pattern metal plate forming portion) for forming a circuit pattern metal plate are formed on the bottom surface of the ceramic substrate receiving portion 22b. A molten liquid injection port (not shown) for injecting molten liquid from a molten liquid injection nozzle (not shown) into the metal substrate forming portion 22a of the lower mold member 22 is formed on the upper mold member 24, and a molten liquid flow path (not shown) extending between the metal substrate forming portion 22a and the metal plate forming portion 22c for the circuit pattern is formed in the lower mold member 22, so that the metal substrate forming portion 22a and the metal plate forming portion 22c for the circuit pattern are connected when the ceramic substrate 10 is placed in the ceramic substrate receiving portion 22b.

[0028] In order to manufacture using the casting mold 20 Figure 1A to Figure 1B The metal-ceramic bonding substrate of the embodiment shown can be configured by placing the ceramic substrate 10 in the ceramic substrate storage portion 22b of the lower mold member 22 and covering the lower mold member 22 with the upper mold member 24, placing the mold in a furnace, reducing the oxygen concentration in the furnace to below 25 ppm (preferably below 15 ppm, more preferably below 10 ppm), and reducing the dew point to below -45°C (preferably below -48°C, more preferably below -50°C), injecting molten aluminum in a manner that contacts the surface of the ceramic substrate, and then cooling the molten aluminum to solidify (solidify).

[0029] The metal-ceramic bonding substrate can be, for example, Figure 3 It is manufactured by the manufacturing device of the metal-ceramic bonding substrate shown.

[0030] Figure 3 The manufacturing device of the metal-ceramic bonded substrate shown is a bonding furnace for bonding a metal member to a ceramic substrate, and includes a front displacement section (not shown), a preheating section 200, a melt injection section 300, a pressurized cooling section 400, a cooling section 500, a rear displacement section (not shown), and a conveying passage 600. The manufacturing device of the metal-ceramic bonded substrate uses a casting mold 20 in which a crucible 34 is provided so as to surround a melt injection port 32 to manufacture the metal-ceramic bonded substrate.

[0031] The preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500 are processing sections capable of maintaining an atmosphere different from the external atmospheric atmosphere (the preheating section 200, the melt injection section 300, and the pressurized cooling section 400 also maintain a temperature different from the external temperature), and are arranged adjacent to each other in a substantially horizontal direction. In addition, the inner walls of the preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500 are covered with an air-permeable heat-insulating material (not shown). As the heat-insulating material, a heat-insulating material such as a fiber-based or foamed plastic-based material is used. In addition, the upper and lower walls of the preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500 are provided with gas introduction nozzles (not shown) extending to the heat insulating material of the upper and lower inner walls, and gas (inert gas such as nitrogen, argon, or reducing gas, etc.) is supplied from the outside of the upper and lower walls to the heat insulating material of the upper and lower walls, and the gas supplied to the heat insulating material can be introduced into the preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500. By introducing the gas through the heat insulating material of the upper and lower inner walls while covering the inner walls with the heat insulating material, the dew point can be reduced to below -45°C (preferably below -48°C).

[0032] On the left side of the preheating section 200 disposed at the far left in the figure, a front replacement section (not shown) is adjacent to the preheating section 200 in a substantially horizontal direction, and a mold insertion port (not shown) is formed on the wall portion on the left side of the front replacement section in the figure. On the right side of the cooling section 500 disposed at the far right in the figure, a rear replacement section (not shown) is adjacent to the cooling section 500 in a substantially horizontal direction, and a mold removal port (not shown) is formed on the side wall on the right side of the rear replacement section in the figure. Vacuuming and replacement (purging) of the internal air with an inert gas or reducing gas such as nitrogen or argon can be repeatedly performed in the front replacement section and the rear replacement section using a rotary pump to reduce the oxygen entering the bonding furnace from the outside.

[0033] In addition, communication ports with gates (not shown) are formed in the partition wall between the front displacement section and the preheating section 200 (not shown), the partition wall between the preheating section 200 and the melt injection section 300, the partition wall between the melt injection section 300 and the pressurized cooling section 400, the partition wall between the pressurized cooling section 400 and the cooling section 500, and the partition wall between the cooling section 500 and the rear displacement section (not shown). In addition, exhaust ports (with adjustable openings) are formed in the front displacement section side of the upper side wall of the preheating section 200 and the rear treatment side of the upper side wall of the cooling section 500, respectively. By adjusting the opening, the pressure difference with the outside can be monitored, so that the pressure in the preheating section 200 is lower than the pressure in the melt injection section 300, and the pressure in the cooling section 500 is lower than the pressure in the pressurized cooling section 400.

[0034] The transport channel 600 extends in a substantially horizontal direction through the mold inlet, the connecting port and the mold removal port, and can transport the mold 20 from the mold inlet to the front replacement section (not shown), the preheating section 200, the molten liquid injection section 300, the pressurized cooling section 400, the cooling section 500 and the rear replacement section (not shown) in sequence, and then take it out from the mold removal port.

[0035] In the preheating section 200, after the ceramic substrate 10 is introduced from the outside and arranged inside, solid aluminum is introduced into the crucible 34, and the mold 20 with the piston 318 embedded in the crucible 34, and the internal air is replaced with an atmosphere of an inert gas or a reducing gas such as nitrogen or argon, the mold 20 is heated by the heater 202 arranged inside to melt the solid metal in the crucible 34 and maintain the temperature of the resulting molten liquid 312.

[0036] In the molten liquid injection part 300, molten aluminum is injected into the mold 20 introduced from the preheating part 200. The molten liquid injection part 300 is provided with a heater 302 for maintaining the temperature of the mold 20 and a molten liquid injection device 310 for injecting the molten liquid 312 into the mold 20. The molten liquid injection device 310 includes a piston 318 for injecting the molten liquid 312 in the crucible 34 into the mold 20 and a piston driving device 320 for driving the piston 318. When the piston 318 in the crucible 34 of the transported mold 20 reaches directly below the molten liquid injection device 310, the piston 318 is moved downward by the piston driving device 320, and the molten liquid 312 in the crucible 34 is injected into the mold 20.

[0037] In the pressurizing and cooling section 400, the molten liquid in the mold 20 introduced from the molten liquid injection section 300 is pressurized and the mold is cooled to solidify the molten liquid. The pressurizing and cooling section 400 is provided with a heater 402 for maintaining the temperature near the molten liquid injection port 32 in the mold 20, a pressurizing device 410 for pressurizing the molten liquid 312 in the mold 20 from the molten liquid injection port 32 of the mold 20, and a cooling device 430 for cooling the portion away from the molten liquid injection port 32 of the mold 20 from top to bottom. The pressurizing device 410 is provided with a piston driving device 420 for moving the piston 318 in the crucible 34 of the transported mold 20 downward when the piston 318 reaches directly below the pressurizing device 410 to pressurize the molten liquid 312 in the mold 20. In addition, the cooling device 430 also has an upper cooling section 432 that approaches or abuts against the upper part of the part away from the molten liquid injection port 32 of the mold 20 to cool the part, a lower cooling section 434 that approaches or abuts against the lower part of the part away from the molten liquid injection port 32 of the mold 20 to cool the part, and cooling section driving devices 436 and 438 that respectively move the upper cooling section 432 and the lower cooling section 434 in their respective up and down directions.

[0038] The pressurized cooling section 400 cools a part of the mold 20 when cooling the mold 20 to form a high temperature side and a low temperature side in the mold 20, and at the same time, the mold 20 is cooled while pressurizing the molten liquid 312 injected into the mold 20 from the high temperature side to the low temperature side, thereby solidifying the molten liquid 312. In this way, the molten liquid 312 is pressurized from the high temperature side to the low temperature side during cooling, that is, pressurization is performed in the opposite direction to solidification, thereby smoothly supplementing the unsolidified molten liquid on the high temperature side to the part of the metal that has solidified on the low temperature side that has shrunk, and finally a metal-ceramic bonding substrate without shrinkage cavities is obtained. In addition, if the cooling is performed in such a manner that the part on the side of the molten liquid injection port 32 in the mold 20 becomes the high temperature side, and the part on the opposite side of the molten liquid injection port 32 becomes the low temperature side with a temperature lower than that of the molten liquid injection port 32, the structure of the mold 20 or the manufacturing device for manufacturing the metal-ceramic bonding substrate can be simplified.

[0039] In the cooling section 500, the mold 20 in which the molten liquid 321 has solidified in the pressurized cooling section 400 is introduced and then fully cooled. The cooling section 500 is provided with a cooling device 530 for cooling the mold 20 from top to bottom. The cooling device 530 includes an upper cooling section 532 that approaches or contacts the upper part of the mold 20 to cool the part, a lower cooling section 534 that approaches or contacts the lower part of the mold 20 to cool the part, and cooling section driving devices 536 and 538 that move the upper cooling section 532 and the lower cooling section 534 in their respective up and down directions to approach or contact the mold 20.

[0040] Example

[0041] Hereinafter, embodiments of the metal-ceramic bonded substrate and the method for producing the same according to the present invention will be described in detail.

[0042] [Example 1]

[0043] A recess (metal substrate forming portion) for forming a substrate having a planar shape of approximately rectangular size of 70 mm × 70 mm × 5 mm is formed on the upper surface of the lower casting member, a recess (ceramic substrate receiving portion) for accommodating a ceramic substrate having a planar shape of approximately rectangular size of 50 mm × 50 mm × 0.6 mm is formed in the approximate center of the bottom surface of the substrate forming portion, a recess (circuit pattern forming portion) for forming a metal plate for a circuit pattern having a planar shape of approximately rectangular size of 48 mm × 48 mm × 0.6 mm is formed in the approximate center of the bottom surface of the ceramic substrate receiving portion, and a molten liquid flow path extending between the metal substrate forming portion and the circuit pattern metal plate forming portion is prepared (with Figure 2A to Figure 2B The casting mold 20 shown is of the same shape as that of a carbon casting mold.

[0044] The ceramic substrate storage portion of the lower mold member of the mold is used to store an aluminum nitride substrate (polycrystalline aluminum nitride substrate (SHAPAL SH-30) manufactured by Tokuyama Co., Ltd.) with a planar shape of approximately rectangular 50 mm × 50 mm × 0.6 mm. The upper mold member is covered and sealed, and the mold is placed in the mold. Figure 3In the joining furnace (shown), a nitrogen atmosphere is formed in the furnace (nitrogen is supplied to the insulation materials of the upper and lower inner walls of the preheating section 200 and the cooling section 500 at a flow rate of 5 L / min, while nitrogen is introduced to the insulation members of the upper and lower inner walls of the melt injection section 300 and the pressurized cooling section 400 at a flow rate of 15 L / min), and the oxygen concentration (in the melt injection section 300) is reduced to 2 ppm and the dew point is reduced to -60°C, and the mold is heated to 730°C by temperature control of the heater. The oxygen concentration and dew point in the joining furnace are measured by a zirconia oxygen concentration meter (LD-300, SA25NW manufactured by Toray Engineering Co., Ltd.) and a dew point meter (Vaisala Corporation) respectively. ア The temperature of the aluminum nitride substrate was measured by using a DRYCAP dew point converter DMT152 manufactured by ISARA. In addition, a pre-measured aluminum melt with a purity of 99.9% by mass (3N) was heated to 740°C, and the melt was injected into the mold from the melt inlet through a nozzle with a narrow portion while removing the oxide film and pressurizing it to 10 kPa with nitrogen. After the aluminum melt was injected into the mold in this way, nitrogen was blown into the melt inlet from the gas pressurizing nozzle to pressurize the aluminum melt in the mold to 10 kPa, and the melt was cooled to solidify, thereby obtaining a metal-ceramic bonding substrate in which an aluminum plate for a circuit pattern was directly bonded to one side of the aluminum nitride substrate and an aluminum substrate was directly bonded to the other side. In this embodiment, vacuuming and nitrogen purging using a rotary pump are repeatedly performed in the front replacement section and the rear replacement section to reduce the oxygen entering the bonding furnace from the outside.

[0045] The metal-ceramic bonded substrate thus obtained was taken out of the casting mold, and cut along the thickness direction at the center of the long side direction (or width direction) of the metal-ceramic bonded substrate using a diamond cutter, and the cut surface was embedded in resin in such a way that the bonding interface between the aluminum nitride substrate and the aluminum substrate, and the bonding interface between the aluminum nitride substrate and the aluminum plate for the circuit pattern could be observed, and then the surface was polished using a rotary grinder. The cut surface was observed using a scanning transmission electron microscope (STEM) and an energy dispersive X-ray analyzer (EDS) device (STEM-EDS analysis), and the maximum thickness of the oxide layer generated at the bonding interface was measured from the STEM bright field image, and the result was 1 nm.

[0046] In addition, the metal-ceramic bonding substrate prepared by the same method as that of the present embodiment is taken out from the casting mold, and the metal-ceramic bonding substrate is masked in a manner so as to leave a 10 mm × 48 mm × 0.6 mm aluminum plate for the circuit pattern in the central portion in the long side direction (or width direction) of the 48 mm × 48 mm × 0.6 mm aluminum plate for the circuit pattern. After etching the unnecessary portion of the aluminum plate for the circuit pattern with a ferric chloride solution, the bonding strength (peel strength) between the aluminum plate for the circuit pattern and the aluminum nitride substrate is measured, and the result is greater than 350 N / cm, which is a sufficiently strong bonding strength.

[0047] [Example 2]

[0048] A metal-ceramic bonding substrate was prepared by the same method as in Example 1, except that aluminum with a purity of 99.99 mass% (4N) was used instead of aluminum with a purity of 99.9 mass% (3N), and STEM-EDS analysis and bonding strength (peel strength) were measured. As a result, the maximum thickness of the oxide layer generated at the bonding interface was 1 nm. The bonding strength (peel strength) was 350 N / cm or more, which was a sufficiently strong bonding strength.

[0049] [Example 3]

[0050] A metal-ceramic bonding substrate was prepared by the same method as in Example 1 except that the dew point was -50°C, and STEM-EDS analysis and bonding strength (peel strength) were measured. As a result, the maximum thickness of the oxide layer generated at the bonding interface was 1 nm. The bonding strength (peel strength) was 350 N / cm or more, which was a sufficiently strong bonding strength.

[0051] [Example 4]

[0052] In addition to turning off the adjustable ( Figure 3 The metal-ceramic bonding substrate was prepared by the same method as in Example 1, except that the opening of the preheating part 200 and the cooling part 500 was set as shown and the oxygen concentration (in the melt injection part 300) was adjusted to 4 ppm. STEM-EDS analysis and bonding strength (peel strength) were performed. As a result, the maximum thickness of the oxide layer generated at the bonding interface was 2 nm. The bonding strength (peel strength) was 350 N / cm, which was a sufficiently strong bonding strength.

[0053] [Example 5]

[0054] In addition to turning off the adjustable ( Figure 3 The metal-ceramic bonding substrate was prepared by the same method as in Example 1, and STEM-EDS analysis and bonding strength (peel strength) were performed, except that the opening of the preheating section 200 and the cooling section 500 (shown) was adjusted to 10 L / min, the flow rate of nitrogen introduced into the preheating section 200 and the cooling section 500 was adjusted to 10 L / min, the oxygen concentration (in the melt injection section 300) was adjusted to 10 ppm, and the dew point was set to -50°C. As a result, the maximum thickness of the oxide layer generated at the bonding interface was 3 nm. The bonding strength (peel strength) was 350 N / cm, which is a sufficiently strong bonding strength.

[0055] [Comparative Example 1]

[0056] A metal-ceramic bonding substrate was prepared by the same method as in Example 5, except that the vacuum and nitrogen purge operations were not performed in the front and rear replacement parts, and the oxygen concentration (in the melt injection part 300) was adjusted to 40 ppm and the dew point was set to -60°C. STEM-EDS analysis and bonding strength (peel strength) were measured. As a result, the maximum thickness of the oxide layer generated at the bonding interface was 5 nm. The bonding strength (peel strength) was 300 N / cm, which was insufficient.

[0057] [Comparative Example 2]

[0058] In addition to providing a gas introduction nozzle that penetrates the upper and lower inner walls of the preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500, instead of introducing the gas through the gas introduction nozzle of the upper and lower inner walls of the preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500, and directly introducing the gas into the preheating section 200, the melt injection section 300, the pressurized cooling section 400, and the cooling section 500, so that the dew point is -40°C, a metal-ceramic bonding substrate was prepared by the same method as in Example 1, and STEM-EDS analysis and bonding strength (peel strength) were measured. As a result, the maximum thickness of the oxide layer generated at the bonding interface was 10 nm. The bonding strength (peel strength) was 280 N / cm, which was insufficient.

[0059] Explanation of symbols

[0060] 10 Ceramic Substrate

[0061] 12 metal substrate

[0062] 14 Metal plates for circuit patterns

[0063] 20. Casting

[0064] 22 Lower side casting member

[0065] 22a Recessed portion for forming metal substrate (metal substrate forming portion)

[0066] 22b Ceramic substrate storage unit

[0067] 22c Circuit pattern forming recess (circuit pattern metal plate forming portion)

[0068] 24 Upper side casting member

[0069] 32 Melt injection port

[0070] 34 Crucible

[0071] 200 Preheating Department

[0072] 202, 302, 402 heaters

[0073] 300 Melt injection part

[0074] 310 Melt injection device

[0075] 312 Molten Liquid

[0076] 314 Melt retention section

[0077] 316 Cylinder

[0078] 316a Melt injection port

[0079] 316b Melt outlet

[0080] 318 Piston

[0081] 320 Piston drive

[0082] 400 Pressurized cooling unit

[0083] 432 Upper cooling section

[0084] 434 Lower cooling section

[0085] 436, 438 Cooling section drive device

[0086] 500 Cooling Unit

[0087] 530 Cooling device

[0088] 532 Upper cooling section

[0089] 534 Lower cooling section

[0090] 536, 538 Cooling section drive device

[0091] 600 Transport Channel

Claims

1. A method for manufacturing a metal-ceramic bonding substrate, characterized in that: A ceramic substrate is arranged in a casting mold, and the casting mold is placed in a furnace whose inner wall is covered with an air-permeable insulating material. The inert gas or reducing gas is introduced by supplying the inert gas or reducing gas into the insulating material of the upper and lower inner walls of the furnace to reduce the oxygen concentration in the furnace to below 25 ppm and the dew point to below -45°C. Molten aluminum is injected in a manner so as to contact one side and the other side of the ceramic substrate, and then the molten aluminum is cooled to solidify, thereby forming an aluminum plate on one side of the ceramic substrate so that the aluminum plate is directly bonded to the ceramic substrate, and forming an aluminum plate on the other side of the ceramic substrate so that the aluminum plate is directly bonded to the ceramic substrate.

2. The method for manufacturing a metal-ceramic bonded substrate according to claim 1, wherein: The aluminum plate is an aluminum plate for circuit patterns.

3. The method for manufacturing a metal-ceramic bonded substrate according to claim 1, wherein: The ceramic substrate is an aluminum nitride substrate, and the aluminum has a purity of 99.9 mass % or more.

4. The method for manufacturing a metal-ceramic bonded substrate according to claim 1, wherein: The pouring of the molten liquid and the cooling are performed while pressurizing.

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