Solder paste composition, a solder paste and a soldering flux

1. A soldering flux, which comprises a resin, a thixotropic agent, an activator, a solvent as well as a long-chain thiol and optionally an organic chelating agent, wherein the long-chain thiol is selected from the group consisting of hexanethiol, octanethiol, decanethiol, dodecanethiol, and/or octadecanethiol and/or mixtures thereof.

2. The soldering flux of claim 1 , wherein the organic chelating agent comprises at least one substituted or unsubstituted o-naphthisodiazine structural element.

3. The soldering flux of claim 1 , wherein the organic chelating agent is selected from 1,10-o-naphthisodiazine, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 4,7-dimethyl-1,10-o-naphthisodiazine, and 4,7-diphenyl-1,10-o-naphthisodiazine, and/or mixtures thereof.

4. The soldering flux of claim 1 , wherein the long-chain thiol, the organic chelating agent or both, is/are present in an amount of 0.2 to 10 wt %, based on the total amount of the soldering flux.

5. The soldering flux of claim 1 , wherein the resin is selected from rosin resins, acid modified rosin resins, hydrogenated rosin resins, disproportionated rosin resins and/or polymerized rosin resins and/or mixtures thereof.

6. The soldering flux of claim 1 , wherein the resin is present in an amount of 10 to 60 wt %, based on the total amount of the soldering flux.

7. The soldering flux of claim 1 , wherein the thixotropic agent is selected from polyamides, hydrogenated castor oils, amide modified hydrogenated castor oils and/or mixtures thereof.

8. The soldering flux of claim 1 , wherein the thixotropic agent is present in an amount of 1 to 10 wt %, based on the total amount of the soldering flux.

9. The soldering flux of claim 1 , wherein the activator is selected from halide containing compounds, organic acids, organic amine compounds and/or mixtures thereof.

10. The soldering flux of claim 1 , wherein the activator is present in an amount of 0.5 to 30 wt %, based on the total amount of the soldering flux.

11. The soldering flux of claim 1 , wherein the solvent is selected from diol monoether, diol diether solvents or mixtures thereof.

12. The soldering flux of claim 1 , wherein the solvent is present in an amount of 10 to 60 wt %, based on the total amount of the soldering flux.

13. The soldering flux of claim 12 , wherein the solvent is diethylene glycol monohexyl ether and/or polyethylene glycol dibutyl ether.

14. The soldering flux of claim 1 , wherein the soldering flux comprises, based on the total amount of the soldering flux:

a) from 10 to 60 wt % of at least one resin;

b) from 1 to 10 wt. % of at least one thixotropic agent;

c) from 0.5 to 30 wt % of at least one activator;

d) from 10 to 60 wt % of at least one solvent; and

e) from 0.2 to 10 wt % of at least one long-chain thiol and/or of at least one organic chelating agent; and

f) from 0 to 30 wt % of at least one additive.