Inhibitor Composition for Racks When Using Chrome Free Etches in a Plating on Plastics Process

Abstract

The invention relates to an aqueous inhibition composition for the inhibition of electrochemical metal plating on polymer surfaces, said inhibition composition comprising an inhibition agent selected from the group of compounds having at least one sulfur and at least one nitrogen atom as well as to a method for the inhibition of an insulated surface of a rack area. The inventive inhibition composition is capable to provide a solution for prohibiting unintended metallization on insulated areas of the racks when non-chromic etching is utilized for plating on plastics processes.

Claims

1. An aqueous inhibition composition for the inhibition of electrochemical metal plating on polymer surfaces, said inhibition composition comprising an inhibition agent selected from the group of compounds having at least one sulfur and at least one nitrogen atom.

2. The inhibition composition according to claim 1, wherein said inhibition agent is at least one according to formula I
R.sub.2NC(S)Y(I) wherein R is independently from each other H or a branched or unbranched C.sub.1 to C.sub.13 alkyl, alkenyl or aryl group, and Y is XR.sup.1, NR.sup.2.sub.2 or N(H)NR.sup.3.sub.2 where X is O or S, and R.sup.1, R.sup.2, R.sup.3 is independently from each other H, an alkali metal or a branched or unbranched C.sub.1 to C.sub.13 alkyl, alkenyl or aryl group.

3. The inhibition composition according to claim 1, wherein said inhibition agent is selected from the group consisting of thioureas, thiocarbamates, and thiosemicarbazides.

4. The inhibition composition according to claim 3, wherein said inhibition agent is a thiourea.

5. The inhibition composition according to claim 1, said composition having a pH-value between 2 and 13.

6. The inhibition composition according to claim 1, wherein said inhibition agent is comprised in a concentration range of between 0.1 g/l and 100 g/l.

7. The inhibition composition according to claim 1, additionally comprising at least one buffering agent.

8. The inhibition composition according to claim 1, additionally comprising agents to increase the solubility of the inhibitor compound in the composition.

9. The inhibition composition according to claim 1, additionally comprising one or more swelling agents for the polymer of the rack insulation.

10. A method for the inhibition of an insulated surface of a rack area, said method comprising the step of contacting the surface with an aqueous inhibition composition comprising an inhibition agent selected from the group of compounds having at least one sulfur and at least one nitrogen atom.

11. The method according to claim 10, wherein the step of contacting the surface with the inhibition composition is included in the process line prior to the etch process step of a plating on plastic line.

12. The method according to claim 10, wherein the step of contacting the surface with the inhibition composition is combined with the step of stripping the racks into a single process step or wherein the step of contacting the surface with the inhibition composition is combined with the step of pre-cleaning into a single process step prior to the etch step.

13. The method according to claim 10, wherein the surface is brought into contact with said inhibition composition at a temperature in a range of between 10 C. and 100 C.

14. The method according to one of the claim 10, wherein the surface is brought into contact with said inhibition composition for a time of 90 min.

15. The method according to one of the claim 10, wherein the insulation on the insulated areas of the rack is a polymer of the group consisting of PVC, polycarbonate, polyamide, polyurethane, PTFE, ECTFE, partly halogenated, especially partly fluorinated, polymers.

16. The method according to claim 10, wherein the surface is brought into contact with said inhibition composition at a temperature in a range of between 40 C. and 70 C.

17. The method according to one of the claim 10, wherein the surface is brought into contact with said inhibition composition for a time of between 10 sec. and 10 min.

18. The inhibition composition according to claim 1, wherein said inhibition agent is comprised in a concentration range of between 1 g/l and 10 g/l.

Description

EXAMPLES

Example 1 (According to the Present Invention)

[0079] An aqueous inhibition composition is provided by adding the following inhibition agents to 1000 ml water. The effect of metallization onto the rack insulation by using an inventive aqueous inhibition composition after the rack hook stripping step and before loading the plastic parts under different conditions is described in following table 1. As a reference the racks were immersed under different conditions into tap water, without adding an inhibition compound.

TABLE-US-00001 TABLE 1 Inhibition Metalli- of rack zation Amount Immersion Temper- metalli- of plastic Inhibition in time in ature in sation in part in agent [g/l] [min] [ C.] pH [area %] [area %] reference 0 1 25 7 0 100 reference 0 30 60 7 0 100 reference 0 30 60 2 0 100 reference 0 30 60 12 0 100 A 1 10 25 6 30 100 A 10 10 25 6 100 100 A 1 10 70 6 100 100 B 1 10 25 8 75 100 B 1 30 25 8 100 100 B 1 10 50 8 100 100 C 1 5 60 4 100 100 D 40 1 40 3 100 100 E 1 5 70 6 100 100 F 5 5 70 8 100 100 G 1 5 70 9 100 100 H 1 5 70 7 100 100 H 0.1 5 70 7 90 100 Wherein A = 2-(methylthio)-2-thiazoline; B = thiourea; C = 4-methylthiosemicarbazide; D = potassium thiocyanate; E = 5-methyl-2-thiouracil; F = 1-diphenyl-2-thiourea; G = 5-methyl-2-thiohydantoine; H = HEAT (hydroxyethyl-allylthiourea).

Example 2 (According to the Invention)

[0080] An aqueous inhibition composition is provided by adding the following inhibition agents to 1000 ml of pre cleaner. The effect of metallization onto the rack insulation by using such an aqueous inhibition composition after loading the plastic parts to be metallized under different conditions is described in following table 2. As reference the racks were immersed under different conditions into the same pre cleaner solution, without addition of the inhibition compound.

TABLE-US-00002 TABLE 2 Inhibition Metalli- of rack zation Amount Immersion Temper- metalli- of plastic Inhibition in time in ature in sation in part in agent [g/l] [min] [ C.] pH [area %] [area %] reference 0 2 25 10 0 100 reference 0 2 50 10 0 100 A 1 2 25 6 20 100 A 5 2 40 6 80 100 A 10 2 70 6 100 100 B 5 2 40 8 90 100 B 5 2 60 8 100 100 C 2 2 60 9 100 100 D 20 1 70 5 100 100 E 2 2 70 6 100 100 F 5 5 70 8 100 100 G 5 2 70 11 100 100 H 1 2 70 7 100 100 H 0.1 2 70 7 70 100 Wherein A = 2-(methylthio)-2-thiazoline; B = thiourea; C = 4-methylthiosemicarbazide; D = potassium thiocyanate; E = 5-methyl-2-thiouracil; F = 1-diphenyl-2-thiourea; G = 5-methyl-2-thiohydantoine; H = HEAT (hydroxyethyl-allylthiourea).