Conductive pattern forming ink, conductive pattern and wiring substrate
A conductive pattern forming ink for forming a conductive pattern on a substrate by a droplet discharge method includes: metal particles; an aqueous dispersion medium in which the metal particles are dispersed; inositol; and a polyglycerol compound having a polyglycerol skeleton. In the ink, H shown in the following formula (I) is 0.050 to 0.70; H = OH ( A ) Mw ( A ) X ( A ) + OH ( B ) Mw ( B ) X ( B ) Formula ( I ) where OH(A) represents an average number of hydroxyl groups in one molecule of the polyglycerol compound, Mw(A) represents a weight-average molecular weight of the polyglycerol compound, X(A) represents a content of the polyglycerol compound in the conductive pattern forming ink in weight percent; and OH(B) represents a number of hydroxyl groups in one molecule of the inositol, Mw(B) represents a molecular weight of the inositol, and X(B) represents a content of the inositol in the conductive pattern forming ink in weight percent.
1. A conductive pattern forming ink for forming a conductive pattern on a substrate by a droplet discharge method, comprising:
metal particles having an average diameter in a range from 1 nm to 100 nm;
an aqueous dispersion medium in which the metal particles are dispersed;
inositol; and
a polyglycerol compound having a polyglycerol skeleton, wherein H shown in the following formula (I) is 0.050 to 0.70;
H
=
OH
(
A
)
Mw
(
A
)
X
(
A
)
+
OH
(
B
)
Mw
(
B
)
X
(
B
)
Formula
(
I
)
wherein OH(A) represents an average number of hydroxyl groups in one molecule of the polyglycerol compound, Mw(A) represents a weight-average molecular weight of the polyglycerol compound, X(A) represents a content of the polyglycerol compound in the conductive pattern forming ink in weight percent; and OH(B) represents a number of hydroxyl groups in one molecule of the inositol, Mw(B) represents a molecular weight of the inositol, and X(B) represents a content of the inositol in the conductive pattern forming ink in weight percent.
2. The conductive pattern forming ink according to claim 1 , wherein the X(A) and the X(B) satisfy a relation of 0.10≦X(A)/X(B)≦20.
3. The conductive pattern forming ink according to claim 1 , wherein the X(A) is 1.0 wt % to 20 wt %.
4. The conductive pattern forming ink according to claim 1 , wherein the X(B) is 1.0 wt % to 15 wt %.
5. The conductive pattern forming ink according to claim 1 , wherein the polyglycerol compound is polyglycerol.
6. The conductive pattern forming ink according to claim 1 , wherein the Mw(A) is 300 to 3000.
7. The conductive pattern forming ink according to claim 1 , wherein a total content of the inositol and the polyglycerol compound in the conductive pattern forming ink is 2.0 wt % to 35 wt %.
8. The conductive pattern forming ink according to claim 1 , wherein the substrate is formed by degreasing and sintering a ceramic formed body made of a material containing ceramic particles and a binder so as to have a sheet like shape, and the conductive pattern forming ink is applied to the ceramic formed body by the droplet discharge method.
9. The conductive pattern forming ink according to claim 1 , wherein the conductive pattern forming ink is a colloidal liquid in which metal colloidal particles composed of the metal particles and a dispersant adsorbing onto surfaces of the metal particles is dispersed in the aqueous dispersion medium.
10. The conductive pattern forming ink according to claim 9 , wherein the dispersant includes one of hydroxy acid and salt of hydroxy acid that having in total three or more of at least one COOH group and at least one OH group, and a number of COOH groups is equal to or larger than a number of OH groups.
11. The conductive pattern forming ink according to claim 9 , wherein the dispersant includes one of mercapto acid and salt of mercapto acid having in total two or more of at least one COOH group and at least one SH group.
12. The conductive pattern forming ink according to claim 9 , wherein the colloidal liquid has a pH of 6 to 12.
13. A conductive pattern formed from the conductive pattern forming ink according to claim 1 .
14. The conductive pattern forming ink according to claim 9 , wherein a content of the metal colloidal particles in the conductive pattern forming ink is in a range from about 1 wt % to about 60 wt %.
15. The conductive pattern forming ink according to claim 14 , wherein the content of the metal colloidal particles in the conductive pattern forming ink is in a range from about 10 wt % to about 50 wt %.