An aqueous acidic copper electroplating bath comprising a source of copper ions, an acid and at least one ureylene polymer selected from polymers according to Formulae, and wherein A represents a unit derived from a diamino compound of the following Formulae and/or R1, R2, R5, and R6 are independently selected from the group consisting of substituted or unsubstituted hydrocarbon residues with 1 to 10 carbon atoms, and -CH 2 CH 2 (OCH 2 CH 2) a -OH, wherein a is an integer from 0 to 4, R3 and R4 are independently selected from the group consisting of (CH 2) p, wherein p is an integer from 2 to 12, and a -[CH 2 CH 2 O] m -CH 2 CH 2 - group, wherein m is an integer from 1 to 40, Z may be the same or different and represents O or S, x and y may be the same or different and are an integer selected from 1, 2 and 3 wherein A' represents a unit derived from a diamino compound of the following Formulae wherein R7 and R8 are independently selected from the group consisting of hydrogen, a substituted or unsubstituted hydrocarbon residue with 1 to 16 carbon atoms, linear or branched alkyl, hydroxyethyl or -CH 2 CH 2 (OCH 2 CH 2) a -OH, wherein a is an integer from 1 to 4, substituted or unsubstituted alkaryl, alkhetaryl, allyl or propargyl and wherein L is a divalent residue, which is selected from the group consisting of -(CH 2) p -, wherein p is an integer from 1 to 12, -CH 2 -CH -CH 2 -, -[CH 2 O] q -CH 2 CH 2 -, -[CH 2 CH 2 O] q -CH 2 CH 2 -, -CH 2 -CH -CH 2 -, and -[CH 2 S] q -CH 2 CH 2 -, -[CH 2 CH 2 S] q -CH 2 CH 2 -wherein q is an integer from 1 to 40, -CH 2 -CH -CH 2 -R9-CH 2 -CH -CH 2 - wherein R9 is selected from the group consisting of a substituted or unsubstituted hydrocarbon residue preferably with 0 to 10 carbon atoms, more preferably from 0 to 2 carbon atoms, -O-CH 2 CH -CH 2 O- and -O-[CH 2 CH 2 O] q -CH 2 O-, wherein q is an integer preferably from 1 to 40, and -CH 2 CH CH 2 -; wherein the single units A may be the same or different, wherein the single units A' may be the same or different wherein the single units L may be the same or different, wherein n represents an integer from 1 to 40, and wherein the ureylene polymers according to Formulae, and have an amino residue at both ends and wherein said aqueous acidic copper electroplating bath is free of intentionally added zinc ions, wherein the concentration of the ureylene polymer according to Formulae, and ranges from 0.001 mg/l to 200 mg/l and wherein the aqueous acidic copper electroplating bath has a pH value of ≤ 1. R1, R2, R5, and R6 are independently selected from the group consisting of substituted or unsubstituted hydrocarbon residues with 1 to 10 carbon atoms, and -CH 2 CH 2 (OCH 2 CH 2) a -OH, wherein a is an integer from 0 to 4, R3 and R4 are independently selected from the group consisting of (CH 2) p, wherein p is an integer from 2 to 12, and a -[CH 2 CH 2 O] m -CH 2 CH 2 - group, wherein m is an integer from 1 to 40, Z may be the same or different and represents O or S, x and y may be the same or different and are an integer selected from 1, 2 and 3 wherein R7 and R8 are independently selected from the group consisting of hydrogen, a substituted or unsubstituted hydrocarbon residue with 1 to 16 carbon atoms, linear or branched alkyl, hydroxyethyl or -CH 2 CH 2 (OCH 2 CH 2) a -OH, wherein a is an integer from 1 to 4, substituted or unsubstituted alkaryl, alkhetaryl, allyl or propargyl and wherein L is a divalent residue, which is selected from the group consisting of -(CH 2) p -, wherein p is an integer from 1 to 12, -CH 2 -CH -CH 2 -, -[CH 2 O] q -CH 2 CH 2 -, -[CH 2 CH 2 O] q -CH 2 CH 2 -, -CH 2 -CH -CH 2 -, and -[CH 2 S] q -CH 2 CH 2 -, -[CH 2 CH 2 S] q -CH 2 CH 2 -wherein q is an integer from 1 to 40, -CH 2 -CH -CH 2 -R9-CH 2 -CH -CH 2 - wherein R9 is selected from the group consisting of a substituted or unsubstituted hydrocarbon residue preferably with 0 to 10 carbon atoms, more preferably from 0 to 2 carbon atoms, -O-CH 2 CH -CH 2 O- and -O-[CH 2 CH 2 O] q -CH 2 O-, wherein q is an integer preferably from 1 to 40, and -CH 2 CH CH 2 -; wherein the single units A may be the same or different, wherein the single units A' may be the same or different wherein the single units L may be the same or different, wherein n represents an integer from 1 to 40, and wherein the ureylene polymers according to Formulae, and have an amino residue at both ends and wherein said aqueous acidic copper electroplating bath is free of intentionally added zinc ions, wherein the concentration of the ureylene polymer according to Formulae, and ranges from 0.001 mg/l to 200 mg/l and wherein the aqueous acidic copper electroplating bath has a pH value of ≤ 1.