Ceramic wiring substrate and process for producing the same

Claim 2

A ceramic wiring substrate comprising a conductive layer provided on a ceramic substrate, said conductive layer being produced by sintering a conductive paste comprising 85 to 97% by weight of a tungsten powder and 15 to 3% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 3

A ceramic wiring substrate comprising a conductive layer provided on a ceramic substrate, said conductive layer being produced by sintering a conductive paste comprising 75 to 95% by weight of a molybdenum powder and 5 to 25% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 4

A ceramic wiring substrate comprising a conductive layer provided on a ceramic substrate, said conductive layer being produced by sintering a conductive paste comprising 75 to 95% by weight of a molybdenum powder and 5 to 25% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 5

A ceramic wiring substrate according to claim 1 or 2, wherein said ceramic substrate is a sintered material comprising pure mullite and a sintering additive for said mullite.

Claim 6

A ceramic wiring substrate according to claim 1 or 2, wherein said ceramic substrate is a sintered material comprising 70 to 85% by weight of pure mullite and 30 to 15% by weight of a sintering additive for said mullite having a composition falling within the range surrounded by the lines connecting points a, b, c and d in a triangular composition diagram, provided that said points a through d represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ a 60 30 10 b 86 4 10 c 95 4 1 d 69 30 1 ______________________________________

Claim 7

A process for producing a ceramic wiring substrate, comprising the steps of: conducting printing on a ceramic green sheet with a conductive paste comprising 85 to 97% by weight of a tungsten powder and 15 to 3% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram; and sintering the resulting ceramic green sheet having a printing thereon at 1550° to 1700° C. in a reducing atmosphere, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 8

A process for producing a ceramic wiring substrate, comprising the steps of: conducting printing on a ceramic green sheet with a conductive paste comprising 85 to 97% by weight of a tungsten powder and 15 to 3% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram; and sintering the resulting ceramic green sheet having a printing thereon at 1550° to 1700° C. in a reducing atmosphere, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 9

A process for producing a ceramic wiring substrate, comprising the steps of: conducting printing on a ceramic green sheet with a conductive paste comprising 75 to 95% by weight of a tungsten powder and 25 to 5% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram; and sintering the resulting ceramic green sheet having a printing thereon at 1550° to 1700° C. in a reducing atmosphere, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 10

A process for producing a ceramic wiring substrate, comprising the steps of: conducting printing on a ceramic green sheet with a conductive paste comprising 75 to 95% by weight of a tungsten powder and 25 to 5% by weight of a sintering additive (for conductive metal) having a composition falling within the range surrounded by the lines connecting points A, B, C, D, E, F, G, H, I, J, K, L, M and N and the lines connecting points O, P, Q, R and S in a triangular composition diagram; and sintering the resulting ceramic green sheet having a printing thereon at 1550° to 1700° C. in a reducing atmosphere, provided that said points A through N and O through S represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ A 46 41 13 B 41 22.5 36.5 C 47 17 36 D 51 12 37 E 56 5 39 F 60 5 35 G 67 5 28 H 71 9 21 I 75 12 13 J 80 12 8 K 84 10 6 L 90 7.5 2.5 M 95 5 0 N 80 16 4 O 51 26 23 P 50.5 23 26.5 Q 55.5 18 26.5 R 63 15 22 S 64 20 16 ______________________________________

Claim 11

A process according to claim 5 or 6, wherein said ceramic green sheet is a composition consisting essentially of pure mullite and a sintering additive for said pure mullite.

Claim 12

A process according to claim 5 or 6, wherein said ceramaic green sheet is a composition comprising 70 to 85% by weight of pure mullite and 30 to 15% by weight of a sintering additive for said pure mullite having a composition falling within the range surrounded by the lines connecting points a, b, c and d in a triangular composition diagram, provided that said points a through d represent the following compositions, respectively: ______________________________________ SiO.sub.2 (wt %) Al.sub.2 O.sub.3 (wt %) MgO (wt %) ______________________________________ a 60 30 10 b 86 4 10 c 95 4 1 d 69 30 1 ______________________________________