Direct metal bonding on carbon-covered ceramic contact projections of a ceramic carrier

Patent metadata

Field	Value
Publication number	US-10000423-B1
Application number	US-201615088088-A
Country	US
Kind code	B1
Filing date	Mar 31, 2016
Priority date	Mar 31, 2016
Publication date	Jun 19, 2018
Grant date	Jun 19, 2018

Abstract

Top and bottom metal plates of a DMB panel stack are simultaneously direct-bonded to the central ceramic sheet in a single high-temperature step. During this step, the DMB panel rests on an array of very small upwardly projecting ceramic contacts of a ceramic carrier. An amount of unoxidized carbon (e.g., a layer of graphite) is disposed on each contact projection such that an amount of carbon is disposed between the top of the contact projection and the metal oxide skin of the bottom metal plate. The carbon bonds with oxygen from the metal oxide skin, thereby preventing connection or direct-bonding of the ceramic contact projection to the second metal plate. This reduces imperfections in the metal of the bottom plate and reduces the amount of ceramic particles bonded to metal at contact sites. As a result, less post-bonding processing is required to make a high quality DMB substrate.

First claim

What is claimed is:

1. A method comprising:
placing a ceramic carrier in contact with a unoxidized carbon member such that ceramic contact projections touch unoxidized carbon of the unoxidized carbon member;
moving the ceramic carrier with respect to the unoxidized carbon member such that unoxidized carbon is left disposed on the ceramic projections of the ceramic carrier;
placing a Direct Metal Bonded (DMB) panel stack on the ceramic carrier such that a bottom surface of a second metal plate of the stack rests on the ceramic contact projections of the ceramic carrier, wherein the stack comprises a ceramic sheet member, a first metal plate disposed in contact with a top surface of the ceramic sheet member, and the second metal plate disposed in contact with a bottom surface of the ceramic sheet member, and wherein a separation layer comprising an amount of unoxidized carbon is disposed on each ceramic contact projection so that at least some unoxidized carbon is disposed between the ceramic contact projection and the overlying second metal plate of the stack; and
in a high-temperature direct-bonding step, when the stack is disposed on the ceramic carrier, causing the first metal plate to be direct-bonded to the top surface of the ceramic sheet member at the same time that the second metal plate is direct-bonded to the bottom surface of the ceramic sheet member.

2. The method of claim 1 , wherein each ceramic contact projection has a contact surface area of less than fifty square millimeters.

3. The method of claim 1 , wherein the ceramic contact projections of the ceramic carrier form a two-dimensional array.

4. The method of claim 1 , wherein less than five percent of the bottom surface of the second metal plate is in contact with unoxidized carbon at the beginning of the high-temperature direct-bonding step.

5. The method of claim 1 , wherein each ceramic contact projection has a contact area of less than fifty square millimeters, wherein the ceramic contact projections of the ceramic carrier form a two-dimensional array, and wherein less than five percent of the bottom surface of the second metal plate is in contact with unoxidized carbon at the beginning of the high-temperature direct-bonding step.

6. The method of claim 1 , wherein the unoxidized carbon is graphite.

7. The method of claim 1 , wherein at least some of the unoxidized carbon oxidizes during the high-temperature direct-bonding step.

8. The method of claim 1 , wherein oxygen from a metal oxide layer of the second metal plate disassociates with metal of the second metal plate in the high-temperature direct-bonding step and chemically reacts with carbon.

9. The method of claim 1 , wherein the high-temperature direct-bonding step occurs in a gaseous atmosphere that is substantially devoid of oxygen gas.

10. The method of claim 1 , wherein the first metal plate in the placing step is a copper plate that has a thin copper oxide skin, and wherein the second metal plate in the placing step is a copper plate that has a thin copper oxide skin.

11. A method comprising:
placing a Direct Copper Bonded (DCB) panel stack on a ceramic carrier such that a bottom surface of a second copper plate of the stack rests on a plurality of ceramic contact projections of the ceramic carrier, wherein the stack comprises a ceramic sheet member, a first copper plate disposed in contact with a top surface of the ceramic sheet member, and the second copper plate disposed in contact with a bottom surface of the ceramic sheet member, wherein a separation layer comprising an amount of unoxidized carbon is disposed on each ceramic contact projection so that at least some unoxidized carbon is disposed between the ceramic contact projection and the overlying second copper plate of the stack
in a high-temperature direct-bonding step, when the stack is disposed on the ceramic carrier, causing the first copper plate to be direct-bonded to the top surface of the ceramic sheet member at the same time that the second copper plate is direct-bonded to the bottom surface of the ceramic sheet member, wherein less than five percent of the bottom surface of the second copper plate is in contact with unoxidized carbon at the beginning of the high-temperature direct-bonding step;
placing the ceramic carrier in contact with a graphite member such that the ceramic contact projections touch graphite of the graphite member; and
moving the ceramic carrier with respect to the graphite member such that graphite is left disposed on the ceramic projections of the ceramic carrier, wherein the step of placing the ceramic carrier on the graphite member and the step of moving the ceramic carrier with respect to the graphite member both occur before the step of placing the DCB panel stack on the ceramic carrier.

12. The method of claim 11 , wherein the first copper plate in the placing step is a copper plate that has a thin copper oxide skin, and wherein the second metal plate in the placing step is a copper plate that has a thin copper oxide skin.

13. The method of claim 12 , wherein the unoxidized carbon is graphite.

14. The method of claim 12 , wherein the bottom surface of the second copper plate is not in contact with any ceramic material during the high-temperature direct-bonding step.

15. A method comprising:
placing a ceramic carrier in contact with a unoxidized material member such that ceramic contact projections touch unoxidized material of the unoxidized material member;
moving the ceramic carrier with respect to the unoxidized material member such that unoxidized material is left disposed on the ceramic projections of the ceramic carrier;
placing a Direct Metal Bonded (DMB) panel stack on a ceramic carrier such that a bottom surface of a second metal plate of the stack rests on a plurality of ceramic contact projections of the ceramic carrier, wherein the stack comprises a ceramic sheet member, a first metal plate disposed in contact with a top surface of the ceramic sheet member, and the second metal plate disposed in contact with a bottom surface of the ceramic sheet member, wherein a layer comprising an unoxidized material is disposed on each ceramic contact projection so that at least some of the unoxidized material is disposed between the ceramic contact projection and the overlying second metal plate of the stack; and
in a high-temperature direct-bonding step, when the stack is disposed on the ceramic carrier, causing the first metal plate to be direct-bonded to the top surface of the ceramic sheet member at the same time that the second metal plate is direct-bonded to the bottom surface of the ceramic sheet member, wherein during the high-temperature direct-bonding step oxygen from a metal oxide layer of the second metal plate disassociates with metal of the second metal plate and oxidizes at least some of the unoxidized material.

16. The method of claim 15 , wherein the layer is a means for preventing the second metal plate from being direct-bonded to any ceramic material other than the ceramic sheet member.

17. The method of claim 16 , wherein the means comprises substantially no ceramic particles.

18. The method of claim 15 , wherein the first metal plate is a copper plate that has a thin copper oxide skin, wherein the second metal plate in the placing step is a copper plate that has a thin copper oxide skin, and wherein the metal oxide layer from which the oxygen dissociates in the high-temperature direct-bonding step is the thin copper oxide skin of the second metal plate.

19. The method of claim 15 , wherein ea

Assignees

• Ixys Corp
• Ixys Llc

Inventors

• Spann Thomas

Classifications

• B23K1/20

  Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating · CPC title

• C04B37/021 Primary

  in a direct manner, e.g. direct copper bonding [DCB] · CPC title

• C04B2237/592

  whereby the interlayer is not continuous, e.g. not the whole surface of the smallest substrate is covered by the interlayer · CPC title

• C04B2237/407

  Copper · CPC title

• C04B2237/64

  Forming laminates or joined articles comprising grooves or cuts · CPC title