Buffer layer to enhance photo and/or laser sintering
View Patent ↗Conductive lines are deposited on a substrate to produce traces for conducting electricity between electronic components. A patterned metal layer is formed on the substrate, and then a layer of material having a low thermal conductivity is coated over the patterned metal layer and the substrate. Vias are formed through the layer of material having the low thermal conductivity thereby exposing portions of the patterned metal layer. A film of conductive ink is then coated over the layer of material having the low thermal conductivity and into the vias to thereby coat the portions of the patterned metal layer, and then sintered. The film of conductive ink coated over the portion of the patterned metal layer does not absorb as much energy from the sintering as the film of conductive ink coated over the layer of material having the low thermal conductivity. The layer of material having the low thermal conductivity may be a polymer, such as polyimide.
1. A method for depositing conductive lines on a substrate comprising:
depositing a metal layer in a pattern on the substrate;
coating a layer of material having a low thermal conductivity over the pattern metal layer and the substrate;
depositing a film of conductive ink over the layer of material having the low thermal conductivity; and
sintering the film of conductive ink.
2. The method as recited in claim 1 , further comprising:
forming a via through the layer of material having the low thermal conductivity thereby exposing a portion of the patterned metal layer, wherein the depositing of the film of conductive ink includes depositing the film of conductive ink into the via to thereby coat the portion of the patterned metal layer with the film of conductive ink, wherein the film of conductive ink coating the portion of the patterned metal layer is also sintered.
3. The method as recited in claim 1 , wherein the substrate has a thermal conductivity greater than the layer of material having the low thermal conductivity.
4. The method as recited in claim 2 , wherein the film of conductive ink coated over the portion of the patterned metal layer does not dissipate as much energy from the sintering as the film of conductive ink coated over the layer of material having the low thermal conductivity.
5. The method as recited in claim 4 , wherein the layer of material having the low thermal conductivity comprises a polymer.
6. The method as recited in claim 4 , wherein the layer of material having the low thermal conductivity comprises polyimide.
7. The method as recited in claim 6 , wherein the polyimide has a thickness of at least 50 microns.
8. The method as recited in claim 6 , wherein the sintering is performed with a photo sintering apparatus.
9. The method as recited in claim 6 , wherein the sintering is performed with a laser sintering apparatus.
10. The method as recited in claim 6 , wherein the polyimide has a thickness of at least 5 microns.
11. The method as recited in claim 6 , wherein the polyimide has a thickness of at least 2.3 microns.
12. The method as recited in claim 6 , wherein the substrate comprises silicon.
13. The method as recited in claim 6 , wherein the substrate comprises ceramic.
14. The method as recited in claim 6 , wherein the film of conductive ink comprises copper nanoparticles.
15. The method as recited in claim 9 , wherein the laser sintering apparatus comprises a solid state diode with an 830 nm wavelength and 800 mW power.
16. The method as recited in claim 15 , wherein the solid state diode has a focus beam size of 15 microns in diameter.
17. Electronic circuitry comprising:
a substrate;
a pattern of metal traces deposited on the substrate;
a layer low thermal conductive material coated over the substrate and the pattern of metal traces deposited on the substrate, wherein vias are formed through the layer of low thermal conductive material over portions of the pattern of metal traces; and
a film of sintered conductive ink coated over the layer of low thermal conductive material coated over the substrate, wherein the film of sintered conductive ink is coated over the portions of the pattern of metal traces within the vias formed through the layer of low thermal conductive material.
18. The electronic circuitry as recited in claim 17 , wherein the substrate has a thermal conductivity greater than the layer of low thermal conductive material.
19. The electronic circuitry as recited in claim 18 , wherein the layer of low thermal conductive material comprises polyimide.
20. The electronic circuitry as recited in claim 19 , wherein the polyimide has a thickness of at least 50 microns.
21. The electronic circuitry as recited in claim 19 , wherein the sintered conductive ink comprises sintered copper nanoparticles sintered with a photo sintering apparatus.
22. The electronic circuitry as recited in claim 19 , wherein the sintered conductive ink comprises sintered copper nanoparticles sintered with a laser sintering apparatus.
23. The electronic circuitry as recited in claim 19 , wherein the polyimide has a thickness of at least 5 microns.
24. The electronic circuitry as recited in claim 19 , wherein the polyimide has a thickness of at least 2.3 microns.
25. The electronic circuitry as recited in claim 19 , wherein the substrate comprises silicon.