Claims
- 1. A method of coating a copper film on a ceramic substrate, said method comprising the steps of:
- forming an undercoat containing copper and bismuth on said ceramic substrate;
- heating said ceramic substrate having said undercoat in an oxidative atmosphere at a temperature between 600 and 1100.degree. C. to obtain a fired undercoat on said ceramic substrate, said fired undercoat being formed with copper oxide particles and a binder phase containing bismuth and copper for bonding between adjacent copper oxide particles, said fired undercoat containing 10 to 90 wt % bismuth;
- reducing said copper oxide particles by the use of a reduced solution to obtain a reduced undercoat having metallic copper particles, said copper particles being partially exposed on a top surface of said reduced undercoat; and
- coating copper on said top surface of said reduced undercoat to form said copper film on said ceramic substrate.
- 2. A method as set forth in claim 1, wherein said undercoat is formed on said ceramic substrate by the use of a mixed resinate paste in which a copper powder is mixed with a bismuth resinate paste.
- 3. A method as set forth in claim 1, wherein said copper oxide particles have an average grain size of 0.1 to 5 .mu.m.
- 4. A method as set forth in claim 3, wherein said average grain size of said copper oxide particles is about 1.5 .mu.m.
- 5. A method of coating a copper film on a ceramic substrate, said method comprising the steps of:
- forming an undercoat containing copper and bismuth on said ceramic substrate;
- heating said ceramic substrate having said undercoat in an oxidative atmosphere at a temperature between 800 and 950.degree. C. to obtain a fired undercoat on said ceramic substrate, said fired undercoat being formed with copper oxide particles and a binder phase containing bismuth and copper for bonding between adjacent copper oxide particles, said fired undercoat contains 30 to 60 wt % bismuth;
- reducing said copper oxide particles by the use of a reduced solution to obtain a reduced undercoat having metallic copper particles, said copper particles being partially exposed on a top surface of said reduced undercoat; and
- coating copper on said top surface of said reduced undercoat to form said copper film on said ceramic substrate.
- 6. A method as set forth in claim 1, wherein said copper coating is performed by electroless plating.
- 7. A method as set forth in claim 1, wherein said copper oxide particles are reduced at a temperature between 20 to 100.degree. C.
- 8. A method as set forth in claim 1, wherein said reducing solution is one of dimethylamine borane and a boron hydride salt.
- 9. A method as set forth in claim 1, wherein said undercoat comprises a copper powder which is treated by a chelating agent of ethylenediamine to form a chelate compound of copper on a surface of the copper powder.
- 10. A method as set forth in claim 1, wherein said undercoat comprises a copper powder which is deposited from a copper plating solution including a chelating agent of ethylenediamine.
- 11. A method of coating a copper film on a ceramic substrate, said method comprising:
- forming a first undercoat of one of copper and bismuth on said ceramic substrate;
- forming a second undercoat of the other one on said first undercoat;
- heating said ceramic substrate having said first and said second undercoats in an oxidative atmosphere at a temperature between 600 and 1100.degree. C. to obtain a fired undercoat on said ceramic substrate, said fired undercoat being formed with copper oxide particles and a binder phase containing bismuth and copper for bonding between adjacent copper oxide particles, said fired undercoat containing 10 to 90 wt % bismuth;
- reducing said copper oxide particles by the use of a reduced solution to obtain a reduced undercoat having metallic copper particles, said copper particles being partially exposed on a top surface of said reduced undercoat; and
- coating copper on said top surface of said reduced undercoat to form said copper film on said ceramic substrate.
Priority Claims (3)
Number |
Date |
Country |
Kind |
P06-009146 |
Jan 1994 |
JPX |
|
P06-009147 |
Jan 1994 |
JPX |
|
P06-009148 |
Jan 1994 |
JPX |
|
Parent Case Info
This is a continuation-in-part of application Ser. No. 08/377,360, filed on Jan. 24, 1995, now abandoned.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
3650747 |
Calligaris et al. |
Mar 1972 |
|
3804638 |
Jonker et al. |
Apr 1974 |
|
4234628 |
DuRose |
Nov 1980 |
|
4539044 |
Abu-Moustafa et al. |
Sep 1985 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
0 189 913 |
Aug 1986 |
EPX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
377360 |
Jan 1995 |
|