Metal/ceramic bonding substrate and method for producing same
After a wet blasting treatment for jetting a slurry, which contains spherical alumina as abrasive grains in a liquid, to the surface of a ceramic substrate 10 of aluminum nitride sintered body so that the ceramic substrate 10 has a residual stress of not higher than −50 MPa and so that the surface of the ceramic substrate 10 to be bonded to the metal plate 14 has an arithmetic average roughness Ra of 0.15 to 0.30 μm, a ten-point average roughness Rz of 0.7 to 1.1 μm and a maximum height Ry of 0.9 to 1.7 μm while causing the ceramic substrate to have a flexural strength of not higher than 500 MPa and causing the thickness of a residual stress layer 10 a formed along the surface of the ceramic substrate 10 to be 25 μm or less, the metal plate 14 of copper or a copper alloy is bonded to the ceramic substrate 10 , which is obtained by the wet blasting treatment, via a brazing filler metal 12 to produce a metal/ceramic bonding substrate which has an excellent bonding strength of the ceramic substrate 10 to the metal plate 14 and which has an excellent heat cycle resistance.
1. A metal/ceramic bonding substrate comprising:
a ceramic substrate of aluminum nitride; and
a metal plate bonded to the ceramic substrate, wherein the ceramic substrate has a residual stress of not higher than −50 MPa and wherein a bonded surface of the ceramic substrate to the metal plate has an arithmetic average roughness Ra of 0.15 to 0.30 μm, and
wherein said ceramic substrate has a flexural strength of 250-450 MPa.
2. A metal/ceramic bonding substrate as set forth in claim 1 , wherein said bonded surface of the ceramic substrate to the metal plate has a ten-point average roughness Rz of 0.7 to 1.1 μm.
3. A metal/ceramic bonding substrate as set forth in claim 1 , wherein said bonded surface of the ceramic substrate to the metal plate has a maximum height Ry of 0.9 to 1.7 μm.
4. A metal/ceramic bonding substrate as set forth in claim 1 , wherein a thickness of a compressed residual stress layer formed along the surface of said ceramic substrate between the surface of the ceramic substrate and a portion of the ceramic substrate at a predetermined depth from the surface of the ceramic substrate is 25 μm or less.
5. A metal/ceramic bonding substrate as set forth in claim 1 , wherein said metal plate is bonded to said ceramic substrate via a brazing filler metal.
6. A metal/ceramic bonding substrate as set forth in claim 1 , wherein said metal plate is made of copper or a copper alloy.
7. A metal/ceramic bonding substrate as set forth in claim 1 , wherein said arithmetic average roughness Ra is in the range of from 0.15 μm to 0.25 μm.
8. A method for producing a metal/ceramic bonding substrate, the method comprising the steps of:
preparing a ceramic substrate of aluminum nitride and a metal plate;
carrying out a treatment for jetting a slurry, which contains abrasive grains in a liquid, to a surface of the ceramic substrate so that the ceramic substrate has a residual stress of not higher than −50 MPa and so that the surface of the ceramic substrate to be bonded to the metal plate has an arithmetic average roughness Ra of 0.15 to 0.30 μm; and
bonding the metal plate to the ceramic substrate obtained by the treatment,
wherein the treated ceramic substrate has a flexural strength of 250-450 MPa.
9. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein the slurry jetting treatment is carried out so that the surface of the ceramic substrate to be bonded to the metal plate has a ten-point average roughness Rz of 0.7 to 1.1 μm.
10. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein the slurry jetting treatment is carried out so that the surface of the ceramic substrate to be bonded to the metal plate has a maximum height Ry of 0.9 to 1.7 μm.
11. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein the slurry jetting treatment is carried out so as to decrease a flexural strength of said ceramic substrate.
12. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein the slurry jetting treatment is carried out so that a thickness of a compressed residual stress layer formed along the surface of said ceramic substrate between the surface of the ceramic substrate and a portion of the ceramic substrate at a predetermined depth from the surface of the ceramic substrate is 25 μm or less.
13. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein said metal plate is bonded to said ceramic substrate via a brazing filler metal.
14. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein said metal plate is made of copper or a copper alloy.
15. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein said abrasive grains are made of spherical alumina.
16. A method for producing a metal/ceramic bonding substrate as set forth in claim 8 , wherein the treatment for jetting the slurry containing the abrasive grains in the liquid is a treatment for jetting a slurry, which contains 10 to 30% by volume of abrasive grains having a higher hardness than that of said ceramic substrate, for 0.02 to 1.0 second with compressed air so that a pressure applied to the surface of said ceramic substrate to be treated is in the range of from 0.10 MPa to 0.25 MPa.