Electroless copper plating solution

1. An electroless aqueous copper plating solution comprising:

a source of copper ions;

a reducing agent or a source of a reducing agent; and

a combination of complexing agents, the combination comprising:

i) polyamino disuccinic acid, polyamino monosuccinic acid, or combinations thereof, and

ii) one or more of a compound which is selected from the group consisting of ethylenediamine tetraacetic acid, N′-(2-Hydroxyethyl)-ethylenediamine-N,N,N′-triacetic acid, and N,N,N′,N′-Tetrakis (2-hydroxypropyl)ethylenediamine.

2. The electroless aqueous copper plating solution according to claim 1 , wherein the combination of complexing agents comprises:

N′-(2-Hydroxyethyl)-ethylenediamine-N,N,N′-triacetic acid and

N,N,N′,N′-Tetrakis (2-hydroxypropyl)ethylenediamine.

3. The electroless aqueous copper plating solution according to claim 1 , wherein the combination of complexing agents comprises polyamino disuccinic acid.

4. The electroless aqueous copper plating solution according to claim 1 , wherein the combination of complexing agents comprises ethylenediaminedisuccinic acid.

5. The electroless aqueous copper plating solution according to claim 1 , wherein the molar ratio of the combination of complexing agents to copper ions is in the range of 1:1 to 10:1.

6. The electroless aqueous copper plating solution according to claim 1 , wherein the reducing agent is one or more of glyoxylic acid and formaldehyde.

7. The electroless aqueous copper plating solution according to claim 1 , wherein the solution further comprises a stabilizing agent.

8. The electroless aqueous copper plating solution according to claim 7 , wherein the stabilizing agent is a dipyridyl, phenanthroline, mercapto-benzothiazole, thio-urea or derivative, cyanide, thiocyanate, iodide, ethanolamine, or a polymer.

9. The electroless aqueous copper plating solution according to claim 1 , wherein the solution further comprises a source of hydroxide ions.

10. A method for electroless copper plating, the method comprising contacting a substrate with an electroless copper plating solution according to claim 1 .

11. The method according to claim 10 , wherein the substrate is made from glass, ceramic or plastics.

12. The method according to claim 10 , wherein the substrate is glass.

13. The method according to claim 10 , wherein a copper layer having a roughness of 5-40 nm, expressed as root-mean-square roughness parameter (RMS), is formed on the substrate.

14. A method of plating a printed circuit board, integrated circuit substrate, wafer, molded interconnect device, display, display component or plastic part comprising contacting the printed circuit boards, integrated circuit substrates, wafers, molded interconnect devices, displays, display components or plastic parts with the electroless copper plating solution according to claim 1 .

15. A method of plating a glass substrate comprising contacting the glass substrates with the electroless copper plating solution according to claim 1 .

16. The method according to claim 10 , wherein the substrate has a surface area of at least 1 m 2 .

17. The method according to claim 12 , wherein the substrate is a glass panel.

18. The method according to claim 15 , wherein the glass substrate is a glass panel for display.

19. The electroless aqueous copper plating solution according to claim 8 , wherein the polymer is a polyacrylamide, polyacrylate, polyethylene glycol, polypropylene glycol, or co-polymer of any of the foregoing.