Controlled wetting and spreading of metals on substrates using porous interlayers and related articles

Patent metadata

Field	Value
Publication number	US-11284510-B2
Application number	US-201916386576-A
Country	US
Kind code	B2
Filing date	Apr 17, 2019
Priority date	Apr 17, 2018
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

The disclosure generally relates to a method of creating patterned metallic circuits (e.g., silver circuits) on a substrate (e.g., a ceramic substrate). A porous metal interlayer (e.g., porous nickel) is applied to the substrate to improve wetting and adhesion of the patterned metal circuit material to the substrate. The substrate is heated to a temperature sufficient to melt the patterned metal circuit material but not the porous metal interlayer. Spreading of molten metal circuit material on the substrate is controlled by the porous metal interlayer, which can itself be patterned, such as having a defined circuit pattern. Thick-film silver or other metal circuits can be custom designed in complicated shapes for high temperature/high power applications. The materials designated for the circuit design allows for a low-cost method of generating silver circuits other metal circuits on a ceramic substrate.

First claim

What is claimed is:

1. A method for forming a patterned metal layer on a substrate, the method comprising:
(a) providing a porous wetting substrate comprising: (i) an underlying substrate, and (ii) a porous first metal layer on a surface of the underlying substrate;
(b) applying a patterned second metal material to the porous wetting substrate and in contact with the porous first metal layer thereon, the second metal having a lower melting point than that of the first metal; and
(c) heating the second metal to a maximum temperature ranging from 600° C. to 1200° C. and at a pressure sufficient to melt the second metal material, wet pores of the porous first metal layer with the molten second metal material, and contact the underlying substrate with the molten second metal material, thereby forming a wetted substrate comprising the underlying substrate, and a patterned, wetted second metal layer adhered to the underlying substrate.

2. The method of claim 1 , wherein the porous first metal layer has a spatial pattern corresponding to that of the patterned second metal material.

3. The method of claim 1 , wherein the patterned second metal material has a spatial pattern corresponding to electronic circuitry.

4. The method of claim 1 , wherein:
the first metal comprises at least one of nickel, aluminum, cobalt, iron, copper, titanium and combinations thereof; and
the second metal comprises at least one of silver, aluminum, tin, bismuth, nickel, copper, gold, cobalt, and combinations thereof.

5. The method of claim 1 , wherein: the underlying substrate comprises a ceramic material.

6. The method of claim 5 , wherein the ceramic material is selected from the group consisting of aluminum oxide, aluminum nitride, gallium nitride, aluminum gallium nitride, beryllium oxide, zirconium oxide, cerium oxide, zinc oxide, silicon carbide, silicon nitride, tungsten carbide, doped derivatives thereof, and combinations thereof.

7. The method of claim 5 , wherein the ceramic material comprises one or more of aluminum oxide (alumina), aluminum nitride, gallium nitride, aluminum gallium nitride, aluminum gallium indium nitride, beryllium oxide, silicon carbide and silicon nitride.

8. The method of claim 5 , wherein the ceramic material comprises a stabilized zirconium oxide (zirconia).

9. The method of claim 5 , wherein the ceramic material comprises one or more of lanthanum strontrium manganite, lanthanum strontium cobaltite, and lanthanum strontium ferrite.

10. The method of claim 1 , wherein the underlying substrate comprises one or more of a metal material and a semiconductor material.

11. The method of claim 1 , wherein the porous first metal layer has a thickness ranging from 0.01 μm to 250 μm.

12. The method of claim 1 , wherein the porous first metal layer comprises pores ranging in size from 0.005 μm to 50 μm.

13. A method for forming a patterned metal layer on a substrate, the method comprising:
(a) providing a porous wetting substrate comprising: (i) an underlying substrate, and (ii) a porous first metal layer on a surface of the underlying substrate, wherein providing the porous wetting substrate comprises:
(a1) applying to the underlying substrate a layer of a first metal mixture comprising a first liquid formulation and first metal particles dispersed in the first liquid formulation, wherein the first metal particles have a size ranging from 0.01 μm to 50 μm; and
(a2) pre-sintering the layer of the first metal mixture at a temperature and pressure sufficient to remove the first liquid formulation and at least partially sinter the first metal particles, thereby forming the porous first metal layer, wherein the porous first metal layer has a thickness ranging from 1 to 10 times the average particle size of the first metal particles prior to pre-sintering, and pre-sintering comprises heating to a maximum temperature that is at least 100° C. lower than a melting point of the first metal and that is sufficiently high to fuse at least some of the first metal particles;

(b) applying a patterned second metal material to the porous wetting substrate and in contact with the porous first metal layer thereon, the second metal having a lower melting point than that of the first metal; and
(c) heating the second metal at a temperature and pressure sufficient to melt the second metal material, wet pores of the porous first metal layer with the molten second metal material, and contact the underlying substrate with the molten second metal material, thereby forming a wetted substrate comprising the underlying substrate, and a patterned, wetted second metal layer adhered to the underlying substrate.

14. The method of claim 13 , wherein the first liquid formulation comprises a polymeric solution.

15. The method of claim 13 , wherein the first metal mixture layer has a thickness ranging from 0.01 μm to 100 μm.

16. The method of claim 13 , wherein pre-sintering comprises heating the layer of the first metal mixture to a maximum temperature ranging from 600° C. to 1400° C.

17. The method of claim 13 , comprising performing pre-sintering in a protective pre-sintering atmosphere comprising at least one of argon and nitrogen.

18. The method of claim 1 , wherein applying a patterned second metal material comprises:
(a1) applying to the underlying substrate a patterned layer of a first metal mixture comprising a first liquid formulation and first metal particles dispersed in the first liquid formulation;
(a2) pre-sintering the patterned layer of the first metal mixture at a temperature and pressure sufficient to remove the first liquid formulation and at least partially sinter the first metal particles, thereby forming a patterned porous first metal layer;
(b1) applying the second metal material to the porous wetting substrate and in contact with the patterned porous first metal layer thereon; and
(c1) heating the second metal at a temperature and pressure sufficient to melt the second metal material, wet pores of the patterned porous first metal layer with the molten second metal material, and contact the underlying substrate with the molten second metal material, thereby forming a wetted substrate comprising the underlying substrate, and a patterned, wetted second metal layer adhered to the underlying substrate with a pattern corresponding to that of the patterned porous first metal layer.

19. The method of claim 1 , comprising performing heating the second metal in a protective atmosphere comprising at least one of argon and nitrogen.

20. The method of claim 1 , wherein the second metal material comprises at least 90 wt. % of the second metal.

21. The method of claim 1 , wherein the second metal material is free from air-reactive components.

22. A method for forming an electronic apparatus, the method comprising:
(a) performing the method of claim 1 to form the wetted substrate comprising the underlying substrate, and a patterned, wetted second metal layer adhered to the underlying substrate, wherein the patterned second metal material has a spatial pattern corresponding to electronic circuitry; and
(b) mounting one or more electronic components to the wetted substrate in electrical connection to an element of the patterned, wetted second metal layer.

23. The method of claim 1 , comprising heating the second metal to a maximum temperature that is at least 300° C. lower than the melting point of the first metal; wherein the second metal comprises silver.

24.

Assignees

• Univ Michigan State

Inventors

• Nicholas Jason Dale
• Zhou Quan
• Bieler Thomas Rector

Classifications

• H05K3/1283 Primary

  After-treatment of the printed patterns, e.g. sintering or curing methods · CPC title

• H05K1/0306 Primary

  Inorganic insulating substrates, e.g. ceramic, glass · CPC title

• H05K3/1208

  Pretreatment of the circuit board, e.g. modifying wetting properties; Patterning by using affinity patterns (providing shape patterns H05K3/1258; adhesion treatments H05K3/38) · CPC title

• H05K2203/1147

  Sealing or impregnating, e.g. of pores · CPC title

• H05K3/3478

  Application of solder preforms; Transferring prefabricated solder patterns · CPC title