Patent ID: 8337606

Claim:
An aqueous solution for treating a metal surface comprising (a) at least one phosphorous compound or its salt represented by the followings formulas wherein R1, R2 and R3 are the same or different and are selected independently from the group consisting of H, a suitable counter ion, C 1 -C 20 -alkyl, which may be substituted or unsubstituted, linear or branched, C 1 -C 6 -alkaryl, which may be linear or branched, substituted or unsubstituted, and aryl, which may be substituted or unsubstituted and wherein n is an integer ranging from 1 to 15 (b) at least one solderability-enhancing compound or its salt represented by the following formula wherein m, n, o and p are integers ranging from 0 to 200 and are the same or different and m+n+o+p is at least 2 wherein R1 and R7 are the same or different and are selected independently from the group consisting of H, a suitable counter ion, C 1 -C 20 -alkyl, which may be substituted or unsubstituted, linear or branched, C 1 -C 6 -alkaryl, which may be linear or branched, allyl, aryl, sulfate, phosphate, halide and sulfonate and wherein each of the R2, R3, R5 and R6 groups may be the same or different and are selected independently from the group consisting of H and C 1 -C 6 -alkyl, which may be linear or branched, substituted or unsubstituted and wherein R4 is selected from the group consisting of C 1 -C 12 -alkylene, which may be linear or branched, substituted or unsubstituted, arylene which may be 1,2-, 1,3- and 1,4-substituted, naphthylene, which may be 1,3-, 1,4-1,5-1,6- and 1,8-substituted, higher annulated arylene, cylcloalkylene, —O—(CH 2 (CH 2 ) n OR1, wherein R1 has the meaning defined above, and moieties represented by the following formulas wherein the substitution independently is 1,2-, 1,3- or 1,4 for each ring and wherein q and r are the same or different and range independently from 0 to 10 and R8 and R9 are selected independently from the group consisting of H and C 1 -C 6 -alkyl,which may be linear or branched; wherein the at least one phosohorous compund (a) represented by the formulas I.-VI. is in an amount of 0.0001 to 0.05 mol/l.