Thick film conductive inks for electronic devices
View Patent ↗Thick film conductive inks for electronic devices, methods for making electronic devices using thick film conductive inks, and electronic devices fabricated by such methods are provided herein. In one example, a thick film conductive ink includes an organic portion and an inorganic portion. The inorganic portion is dispersed in the organic portion to define a paste. The inorganic portion includes metallic copper powder, cupric oxide, and elemental boron. The thick film conductive ink includes substantially no glass.
1. A thick film conductive ink for an electronic device, the thick film conductive ink comprising:
an organic portion; and
an inorganic portion dispersed in the organic portion defining a paste, wherein the inorganic portion comprises metallic copper powder, cupric oxide, and elemental boron, and wherein the thick film conductive ink comprises substantially no glass, wherein the metallic copper powder comprises a first copper powder, a second copper powder, and/or a third copper powder, wherein the first copper powder has a first average surface area of from about 0.3 to about 0.8 m 2 /g, the second copper powder has a second average surface area of from about 0.8 to about 1.5 m 2 /g, and the third copper powder has a third average surface area of from about 1.5 to about 2.5 m 2 /g, and wherein the metallic copper powder comprises the first copper powder that has a median particle size of about 4.5 to about 10.5 μm.
2. The thick film conductive ink of claim 1 , wherein the inorganic portion comprises substantially no lead.
3. The thick film conductive ink of claim 1 , wherein the inorganic portion consists essentially of the metallic copper powder, cupric oxide, and elemental boron.
4. The thick film conductive ink of claim 1 , wherein the organic portion is present in an amount of from about 10 to about 30 wt. % of the thick film conductive ink.
5. The thick film conductive ink of claim 1 , wherein the inorganic portion is present in an amount of from about 70 to about 90 wt. % of the thick film conductive ink.
6. The thick film conductive ink of claim 1 , wherein the metallic copper powder is present in an amount of from about 50 to about 85 wt. % of the thick film conductive ink.
7. The thick film conductive ink of claim 1 , wherein cupric oxide is present in an amount of from about 3 to about 23 wt. % of the thick film conductive ink.
8. The thick film conductive ink of claim 1 , wherein elemental boron is present in an amount of from about 0.5 to about 5 wt. % of the thick film conductive ink.
9. The thick film conductive ink of claim 1 , wherein the organic portion comprises an organic liquid having a boiling point of from about 220 to about 300° C. at 1 atmosphere of pressure.
10. The thick film conductive ink of claim 1 , wherein the organic portion comprises 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.
11. The thick film conductive ink of claim 10 , wherein 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is present in an amount of from about 8 to about 25 wt. % of the thick film conductive ink.
12. The thick film conductive ink of claim 1 , wherein the organic portion comprises ethyl cellulose.
13. The thick film conductive ink of claim 12 , wherein ethyl cellulose is present in an amount of from about 0.5 to about 3 wt. of the thick film conductive ink.
14. The thick film conductive ink of claim 1 , wherein the organic portion comprises butyl diglyme.
15. The thick film conductive ink of claim 14 , wherein butyl diglyme is present in an amount of from about 1 to about 4 wt. % of the thick film conductive ink.
16. The thick film conductive ink of claim 1 , wherein the metallic copper powder has a median particle size of from about 0.01 to about 10.5 μm.
17. A method for making an electronic device, the method comprising the steps of:
depositing a thick film conductive ink overlying a substrate, wherein the thick film conductive ink comprises:
an organic portion; and
an inorganic portion dispersed in the organic portion defining a paste, wherein the inorganic portion comprises metallic copper powder, cupric oxide, and elemental boron, and wherein the thick film conductive ink comprises substantially no glass, wherein the metallic copper powder comprises a first copper powder, a second copper powder, and/or a third copper powder, wherein the first copper powder has a first average surface area of from about 0.3 to about 0.8 m 2 /g, the second copper powder has a second average surface area of from about 0.8 to about 1.5 m 2 /g, and the third copper powder has a third average surface area of from about 1.5 to about 2.5 m 2 /g, and wherein the metallic copper powder comprises the first copper powder that has a median particle size of about 4.5 to about 10.5 μm; and
firing the thick film conductive ink to form a conductor overlying the substrate.
18. The method of claim 17 , wherein depositing comprises depositing the thick film conductive ink in a single print to form a first conductor paste layer, and wherein firing comprises firing the first conductor paste layer to form the conductor having a single print fired thickness of from about 0.0254 to about 0.1524 mm.
19. An electronic device comprising:
a substrate; and
a conductor overlying the substrate and comprising fused/sintered metallic copper, cupric oxide, boron trioxide, and substantially no glass, wherein the metallic copper comprises a first copper powder, a second copper powder, and/or a third copper powder, wherein the first copper powder has a first average surface area of from about 0.3 to about 0.8 m 2 /g, the second copper powder has a second average surface area of from about 0.8 to about 1.5 m 2 /g, and the third copper powder has a third average surface area of from about 1.5 to about 2.5 m 2 /g, and wherein the metallic copper powder comprises the first copper powder that has a median particle size of about 4.5 to about 10.5 μm.