Copper paste, wick formation method, and heat pipe

1. A copper paste for forming a wick of a heat pipe, the copper paste comprising:

copper particles;

thermally decomposable resin particles comprising a thermally decomposable resin A;

a dispersion medium for dispersing the copper particles and the thermally decomposable resin particles; and

a thermally decomposable resin B that is soluble in the dispersion medium.

2. The copper paste according to claim 1 , wherein a content of the thermally decomposable resin particles is 3 to 30 parts by mass with respect to 100 parts by mass of a total amount of the copper particles and the thermally decomposable resin particles.

3. The copper paste according to claim 1 , wherein the thermally decomposable resin particles have a volume average particle diameter of 5 to 40 μm.

4. The copper paste according to claim 1 , wherein a 95% thermal decomposition temperature of the thermally decomposable resin particles and the thermally decomposable resin B is 450° C. or lower.

5. The copper paste according to claim 1 , wherein a content of the thermally decomposable resin B is 1 to 25 parts by mass with respect to 100 parts by mass of the copper particles.

6. The copper paste according to claim 1 , wherein a proportion of copper particles having a particle diameter of 1.5 μm or less is 10% by volume or more based on a total amount of the copper particles.

7. The copper paste according to claim 1 , wherein the copper paste has a viscosity at 25° C. of 10 to 120 Pa·s.

8. A method for forming a wick of a heat pipe, the method comprising:

a step of printing the copper paste according to claim 1 ; and

a step of sintering the copper paste.

9. A heat pipe comprising a wick including a sintered body of the copper paste according to claim 1 .

10. The copper paste according to claim 1 , wherein an amount of dissolution of the thermally decomposable resin particles in 100 g of the dispersion medium at 25° C. is 1 g or less.

11. The copper paste according to claim 10 , wherein an amount of dissolution of the thermally decomposable resin B in the dispersion medium at 25° C. is 5 parts by mass or more with respect to 100 parts by mass of the dispersion medium.

12. The copper paste according to claim 1 , wherein an amount of dissolution of the thermally decomposable resin B in the dispersion medium at 25° C. is 5 parts by mass or more with respect to 100 parts by mass of the dispersion medium.

13. The copper paste according to claim 1 , wherein thermally decomposable resin A is selected from the group consisting of a (crosslinked) polycarbonate, (crosslinked) poly(meth)acrylic acid, a (crosslinked) poly(meth)acrylic acid ester, a (crosslinked) polyester, and a (crosslinked) polyether.

14. The copper paste according to claim 13 , wherein thermally decomposable resin B is selected from the group consisting of a polycarbonate, poly(meth)acrylic acid, a poly(meth)acrylic acid ester, a polyester, and a polyether.

15. The copper paste according to claim 1 , wherein thermally decomposable resin B is selected from the group consisting of a polycarbonate, poly(meth)acrylic acid, a poly(meth)acrylic acid ester, a polyester, and a polyether.

16. A copper paste for forming a wick of a heat pipe, the copper paste comprising:

a dispersion medium;

copper particles dispersed in the dispersion medium;

thermally decomposable resin particles comprising a thermally decomposable resin A dispersed in the dispersion medium; and

a thermally decomposable resin B, at least a portion of which is dissolved in the dispersion medium.

17. The copper paste according to claim 16 , wherein an amount of dissolution of the thermally decomposable resin particles in 100 g of the dispersion medium at 25° C. is 1 g or less, and an amount of dissolution of the thermally decomposable resin B in the dispersion medium at 25° C. is 5 parts by mass or more with respect to 100 parts by mass of the dispersion medium.

18. The copper paste according to claim 16 , wherein thermally decomposable resin A is selected from the group consisting of a (crosslinked) polycarbonate, (crosslinked) poly(meth)acrylic acid, a (crosslinked) poly(meth)acrylic acid ester, a (crosslinked) polyester, and a (crosslinked) polyether, and thermally decomposable resin B is selected from the group consisting of a polycarbonate, poly(meth)acrylic acid, a poly(meth)acrylic acid ester, a polyester, and a polyether.

19. The copper paste according to claim 16 , wherein a content of the thermally decomposable resin particles is 3 to 30 parts by mass with respect to 100 parts by mass of a total amount of the copper particles and the thermally decomposable resin particles.

20. A heat pipe comprising a wick including a sintered body of the copper paste according to claim 16 .