Electroless copper-nickel plating electrolyte for plating on plastics and method for using the same

Abstract

A method of selectively metallizing a multi-component molded plastic part. The multi-component molded plastic part comprises at least one first region to be metallized formed of a first plastic and at least one second region that is not to be metallized formed of a second plastic. The method includes the steps of (a) contacting the multi-component molded plastic part with a chromic acid-free etchant, wherein the chromic acid-free etchant comprises manganese sulfate; (b) optionally, neutralizing the manganese sulfate to Mn2+ ions; (c) activating surfaces of the plastic part with an activator; (d) contacting the activated surfaces of the plastic part with an accelerator; and (e) depositing an electroless plating layer on the surfaces of the multi-component molded plastic part with an electroless plating electrolyte comprising nickel and copper to form an electroless copper-nickel layer on substantially only the first region formed of the first plastic.

Description

ELECTROLESS COPPER-NICKEL PLATING ELECTROLYTE FOR PLATING ON PLASTICS AND METHOD FOR USING THE SAMEFIELD OF THE INVENTION

[0001] The present invention relates generally to a process for plating plastic parts, including multi-component molded plastic parts, an electroless copper-nickel plating electrolyte for use in the process, and a plated plastic part.BACKGROUND OF THE INVENTION

[0002] Plating on plastics (POP) is a technique for metallizing non-conductive plastic parts and other plastic substrates and components used in wide-ranging applications, including, for example, the automotive industry. One of the most common plastics used for plating is a copolymer of acrylonitrile, styrene and butadiene (ABS). ABS is a two-phase plastic consisting of a hard phase of acrylonitrile / styrene copolymer and a softer phase consisting of polybutadiene. Sometimes, the ABS polymer is combined with a percentage of polycarbonate (PC) to make ABS / PC. ABS and ABS / PC parts can be used to produce interior and exterior decorative plated parts in the automotive industry.

[0003] In order to plate these plastic parts, they are first mounted on metal plating racks in order to transmit the plating current to the plastic parts after the initial metallization stage. The metal plating racks are coated with a coating, which is typically a PVC plastisol coating, to prevent extraneous plating from depositing on the metal plating racks (i.e., rack metallization).

[0004] In addition, to parts that are injection molded from one plastic (i.e., ABS or ABS / PC), there is also a demand for decorative plating of 2K (two-component) parts molded from two types of plastics. In 2K injection molding (also known as 2 shot molding), the two materials are processed into a single plastic item to form multi-component molded plastic parts. Using a 2K injection molding machine, the plastic molding technique mixes two or more materials into one final plastic product, combining the benefits of the two or more materials with differing qualities into the multicomponent molded plastic parts. For example, the first plastic may be ABS or ABS / PC and the second plastic may be PC.

[0005] In plating multi-component molded plastic parts, it is often desirable and / or required that only a first plastic material is plated; and other plastic materials are not plated and must remain at least substantially free of plating. However, selective plating of multi-component molded plastic parts can be challenging and a close monitoring of the steps in the process is critical to achievegood results, especially in terms of selectivity and preventing extraneous plating from depositing on metal plating racks to which the plastic parts are attached. The selectivity of 2K (and other multi-component) parts is influenced by both the material and injection molding conditions, making some parts more challenging to plate or coat with metal.

[0006] The metal plating rack typically comprises metal at least partially coated with an insulating plastic such as polyvinyl chloride (PVC) plastisol. The presence of the metal enables transmittance of a plating current to a component supported by the metal plating rack during an electroplating process. The metal preferably comprises copper and / or iron alloys in order to transmit electric current to the components during electroplating.

[0007] The plastic parts may be held in place on the metal plating rack by support clips. In order to transmit current, these support clips may have a small uncoated area so that electrical contact is maintained during processing of the components. The remainder of the support is coated with the insulating plastic coating, typically PVC plastisol, in order to prevent the entire support from being electroplated. Typically, the part of the support where a contact is made to the electrical supply for supplying the electroplating currents is not coated.

[0008] There are a number of steps involved in preparing the plastic part for subsequent plating thereon in order to render it electrically conductive for a subsequent plating operation. These steps have typically included: a) Chromic acid etching; b) Palladium activation with a palladium tin activator solution; c) Acceleration with an accelerator solution to remove tin, leaving palladium to act as a catalyst for electroless plating; and d) Electroless nickel (or electroless copper) plating.

[0009] In the etching step, surfaces of the plastic part are roughened to provide good adhesion during the subsequent steps and render the surfaces hydrophilic. This initial etching step has traditionally been accomplished using a solution of chromic acid and sulfuric acid, which oxidizes (primarily) the polybutadiene phase of the AB S to produce the necessary roughening of the plastic. The chromic acid solution is highly penetrating and some of it is absorbed by the PVC plastisol coating the metal plating rack.

[0010] In the palladium activation step, the metal plating racks holding the plastic parts are typically immersed in an aqueous solution of a precious metal catalyst (i.e., a palladium colloid)which deposits a thin layer of the catalyst on the plastic surface. This then acts as a catalyst for subsequent electroless nickel (or copper) plating to produce a thin metallic layer on the plastic components which can be treated for further metallization, followed by copper electroplating. After activation of surfaces of the plastic part with a palladium tin activator solution, tin in the solution is removed with an accelerator solution. Tin inhibits the electroless plating process, and after acceleration, most of the tin is removed from the surfaces of the plastic part and palladium remains on the surface of the plastic part which acts as a catalyst for the electroless plating step.

[0011] Following immersion in colloidal palladium, some of the colloid becomes attached to the PVC plastisol, but is inactivated by the absorbed chromic acid. Thus, when the racks holding the plastic components are immersed in the electroless nickel (or copper) solution, the catalyst adsorbed on the ABS components catalyzes the deposition of nickel or copper onto the components, but due to the presence of chromic acid on the PVC plastisol on the metal plating rack, no nickel or copper is deposited on the metal plating rack. However, while rack metallization can be successfully avoided when using a chromic acid etch, it can be difficult to plate multicomponent molded plastic parts with good results in terms of selectivity.

[0012] In addition, chromic acid is a Category 1 carcinogen and its use is currently being phased out in Europe and other jurisdictions. Since it is very likely that the use of chromic acid etchants will be phased out completely due to their toxicity, chromic acid-free etches must be used in the plating on plastics process.

[0013] New etchants for ABS and ABS / PC plastics have been developed that use a combination of acids with manganese III ions (see, for example, U.S. Pat. No. 9,534,306 and U.S. Pat. No. 10,260,000, both to Pearson, the subject matter of each of which is herein incorporated by reference in its entirety). However, these chromic acid-free etchants differ in their performance from conventional chromic acid etchants and the plating cycle must be modified in order to achieve a good result in terms of selectivity when plating multi-component molded plastic parts and to prevent rack metallization. Unlike the chromic acid etchants described above, these manganese- based etchants do not inhibit the attachment of the palladium colloid to PVC plastisol coatings effectively enough to prevent the deposition of nickel or copper during the electroless deposition stage of the process, resulting in the occurrence of significant rack metallization.

[0014] Depending on the activator and its level of activity, other problems can arise in processes that do not use a chromic acid etchant. If a less active activator is used, a “conditioner” may benecessary to ensure an increased and uniform palladium uptake to achieve uniformly created parts. If used, the conditioner may contain an amine compound that helps adhere the palladium to the plastic part and increased palladium uptake. On the other hand, if a more active activator is used, a conditioner may not be required. However, in both cases, it is difficult to obtain a good selectivity when plating multi-component molded plastic parts while preventing rack metallization and / or to obtain a good selectivity with less rack metallization but with the added risk of producing a plating layer that contains defects.

[0015] The plating of multi-component molded plastic parts with a high selectivity can be very challenging, especially in a chromic acid-free process. The quality of the plated multi-component molded plastic parts depends on various factors including the plating parameters of the electroless nickel (or electroless copper) plating electrolyte, the type of palladium activator, and the type of accelerator, all of which influence the growth of the electroless nickel layer. If these process steps are not well coordinated, defects, including non-coated areas, loss of selectivity, and strong rack metallization, can occur.

[0016] To date, no suitable plating on plastics process has been identified that uses a chromic acid- free etch and that is capable of achieving good selectivity on multi-component molded plastic parts without also exhibiting strong rack metallization. Further, while rack plating inhibitors have been suggested for use in processes, the use of rack plating inhibitors typically requires additional tanks, adding yet another step to the plating process, and has led to mixed results.

[0017] U.S. Pat. No. 4,482,596 to Gulla et al., the subject matter of which is herein incorporated by reference in its entirety, describes the deposition of copper-nickel layers. However, Gulla describes a plating process that includes the steps of (a) preparing the parts for plating using scrub cleaning; (b) conditioning; (c) catalyst pre-dip; (d) catalysis in a tin-palladium colloidal catalyst; (e) immersion in an accelerator; and (f) electroless copper-nickel plating at a temperature of 120°F (~49°C). The elevated temperature during electroless copper-nickel plating indicated that the plating process and conditions were chosen in order to deposit a highly conductive layer in the shortest possible time. However, the process described in Gulla does not use a chromic acid-free etchant and therefore does not recognize any of the issues associated with its use. Further, there is no appreciation on the issues associated with selective plating of multi-component molded plastic parts.

[0018] It would be desirable to provide an improved plating on plastics process that can overcome these deficiencies, including a process that uses a chromic acid-free etchant, provides a good result in terms of selectivity when plating multi-component molded plastic parts, and results in no rack metallization.SUMMARY OF THE INVENTION

[0019] It is an object of the present invention to provide a process for selective plating of multicomponent molded plastic parts that does not use a chromic-acid etchant.

[0020] It is another object of the present invention to provide a process for selective plating of multi-component molded plastic parts that uses a manganese-based etchant.

[0021] It is another object of the present invention to provide a process for preparing multicomponent molded plastic parts for subsequent electroplating thereon that provides good plating selectivity.

[0022] It is another object of the present invention to provide a process for preparing multicomponent molded plastic parts for subsequent electroplating thereon to provide an electroless deposit that has a high conductivity.

[0023] It is another object of the present invention to provide a process for preparing multicomponent molded plastic parts for subsequent plating thereon that allows for direct plating of electroless copper-nickel plated parts in a copper-nickel electroplating bath without any intervening steps.

[0024] It is another object of the present invention to provide a process for preparing multicomponent molded plastic parts for subsequent plating thereon that exhibits minimal to no rack metallization.

[0025] It is still another object of the present invention to provide a process for selective plating of multi-component molded plastic parts that does not require a rack plating inhibitor.

[0026] To that end, in one embodiment, the present invention relates generally to a method of preparing a multi-component molded plastic part for electroplating thereon, wherein the multicomponent molded plastic part comprises at least one first region to be metallized formed of a first plastic and at least one second region that is not to be metallized formed of a second plastic, the method comprising the steps ofa. contacting the multi-component molded plastic part with a chromic acid-free etchant to etch selected surfaces of the multi-component molded plastic part, wherein the chromic acid-free etchant comprises manganese species with an oxidation state higher than 2; b. optionally, reducing the manganese species with the oxidation species higher than 2 to Mn2+; c. optionally, conditioning the selected surfaces of the two-component molded plastic part with a conditioner; d. activating the selected surfaces of the multi-component molded plastic part with a precious metal colloid activator comprising a first core metal and a second metal; e. contacting the activated surfaces of the multi-component molded plastic part with an accelerator, wherein the accelerator removes the second metal from the treated surfaces; and f. depositing an electroless plating layer on the selected surfaces of the multicomponent molded plastic part with an electroless plating electrolyte comprising nickel and copper; wherein an electroless copper-nickel layer is deposited on the first region formed of the first plastic and does not substantially deposit on the second region formed of the second plastic.

[0027] In another embodiment, the present invention also relates generally to a selectively metallized multi-component molded plastic part comprising at least one first region formed of a first plastic and at least one second region formed of a second plastic, wherein the at least one first region formed of the first plastic is metallized with a first layer comprising a copper-nickel layer and a second layer comprising copper, wherein the second layer is formed directly on the first layer, and wherein the at least one second region formed of the second plastic is at least substantially free of metallization.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In order to overcome the deficiencies in a plating on plastics process for plating multicomponent molded plastic parts, especially with the use of a chromic acid-free etchant, theinventors have surprisingly found that the use of an electroless copper-nickel plating electrolyte in a process for preparing multi-component molded plastic parts for subsequent plating thereon, especially in combination with optimal process conditions, can produce good results in terms of selectivity and rack metallization.

[0029] As used herein, “a,” “an,” and “the” refer to both singular and plural referents unless the context clearly dictates otherwise.

[0030] As used herein, the term “about” refers to a measurable value such as a parameter, an amount, a temporal duration, and the like and is meant to include variations of + / -15% or less, preferably variations of + / -10% or less, more preferably variations of + / -5% or less, even more preferably variations of + / -!% or less, and still more preferably variations of + / -0.1% or less of and from the particularly recited value, in so far as such variations are appropriate to perform in the invention described herein. Furthermore, it is also to be understood that the value to which the modifier “about” refers is itself specifically disclosed herein.

[0031] As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, are used for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0032] It is further understood that the terms “front” and “back” are not intended to be limiting and are intended to be interchangeable where appropriate.

[0033] As used herein, the terms “comprises” and / or “comprising” and / or “having” and / or “including” specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term “consisting of’ is intended to mean that no other elements may be present except for those listed. As used herein, the term “consisting essentially of’ is intended to mean that no other elements may be present other than those listed unless those other elements do not materially affect the basic and novel characteristics of the invention.

[0034] As used herein, the term “multi-component molded plastic part” means a plastic part prepared by injection molding of at least two types of plastic materials to prepare a single plastic item containing the at least two types of plastic materials. While the examples herein are directedto two types of plastic materials, it is contemplated that at least three types of plastics or at least four types of plastics could also be used.

[0035] As used herein, the term “good selectivity” means that plating only occurs on one of the plastic materials in the multi-component molded plastic part (and / or in desired areas of the plastic part) without any substantial plating occurring (i.e., less than about 1% unwanted metallization) on the other plastic material of the multi-component molded plastic part.

[0036] As used herein, the term “rack metallization” refers to the presence of unwanted extraneous plating material deposited on surfaces of the rack or support.

[0037] As used herein, the term “plating speed” refers to the speed that the plating electrolyte plates metal onto the multi-component molded plastic part.

[0038] As used herein, the term "skip plating” refers to a defect that occurs in which desired areas of the multi-component molder plastic part are not plated, creating an uneven and undesirable surface.

[0039] As used herein the term “support” or “metal plating rack” refers to as structure that is configured for and suitable for supporting one or more multi-component molded plastic parts. Suitable shapes and configurations of metal plating racks are known in the art. The rack may comprise, for example, one or more hooks or support clips to support the multi-component molded plastic parts during the process. The metal plating rack may also comprise a cathode and / or anode for use in an electroplating plating step.

[0040] In one embodiment, the present invention relates generally to a method of preparing a multi-component molded plastic part for electroplating thereon, wherein the multi-component molded plastic part comprises at least one first region to be metallized formed of a first plastic and at least one second region that is not to be metallized formed of a second plastic, the method comprising the steps of: a. contacting the multi-component molded plastic part with a chromic acid-free etchant to etch selected surfaces of the multi-component molded plastic part, wherein the chromic acid-free etchant comprises manganese species with an oxidation state higher than 2; b. optionally, reducing the manganese species with the oxidation species higher than 2 to Mn2;c. optionally, conditioning the selected surfaces of the multi-component molded plastic part with a conditioner; d. activating the selected surfaces of the multi-component molded plastic part with a precious metal colloid activator comprising a first core metal and a second metal; e. contacting the activated surfaces of the multi-component molded plastic part with an accelerator, wherein the accelerator removes the second metal from the treated surfaces; and f. depositing an electroless plating layer on the selected surfaces of the multicomponent molded plastic part with an electroless plating electrolyte comprising nickel and copper; wherein an electroless copper-nickel layer is deposited on the first region formed of the first plastic and does not substantially deposit on the second region formed of the second plastic.

[0041] The development of the electroless copper-nickel plating electrolyte was found to be a big step-forward in solving problems related to selectivity and rack metallization in a plating on plastics process for plating multi-component molded plastic parts. It was found that, if an electroless copper-nickel plating electrolyte is used to plate a copper-nickel layer on the prepared plastic surface, a high selectivity on multi-component molded plastic parts can be reached, especially when the parts are treated in chromic acid-free etchant. In addition, no rack metallization is observed, even in a plating process in which a conditioner is used to increase the amount of adsorbed palladium and / or a more active activator is used.

[0042] The inventors of the present invention have also found that both ABS and ABS / PC can be plated without rack metallization occurring. In addition, multi-component molded plastic parts, especially in which the first plastic is ABS or ABS / PC and the second plastic is PC, plated with a copper-nickel plating electrolyte in a plating process as described herein, perform well when subjected to a peel strength test.

[0043] It was discovered that the conditions of the accelerator need to be adjusted in order to produce a good result in terms of selectivity and no metallization. Typically, the accelerator is used at a temperature of about 45-50°C for 2-3 minutes before plating in an electroless nickel bath. However, when an electroless copper-nickel plating electrolyte is used as described herein, the treatment time at high temperatures needs to be significantly reduced. As described in the examplesbelow, the best results were obtained with diluted solutions when the accelerator was used at a temperature with the range of about 25 to about 35°C, more preferably at about 30°C. In addition, both alkaline and acid accelerators are known and can be used in the process described herein.

[0044] The inventors of the present invention have also discovered that the use of the electroless copper-nickel plating electrolyte described herein instead of a standard nickel plating electrolyte enables the user to work with a shorter treatment cycle. It is a common practice to apply either a copper immersion layer or to plate a nickel strike layer on top of the nickel layer plated from a standard electroless nickel bath in order to increase the conductivity and ensure that the subsequently electroplated layer is defect-free.

[0045] However, the use of an immersion copper process or a nickel strike plating process extends the plating line by one additional step. In contrast, when using the electroless copper-nickel plating electrolyte described herein, the use of an immersion copper process or a nickel strike plating process are not required. Due to the high copper content (>95% Cu) the electroless copper-nickel layer of the instant invention is much more conductive, and the conductivity corresponds to the conductivity of pure nickel layer treated in an immersion copper solution or is even better. Therefore, it is possible to avoid the immersion copper or the nickel strike process and the plastic parts can be directly plated in an acidic copper electrolyte after deposition of the electroless copper- nickel layer. The plating cycle is reduced by one step.

[0046] An additional advantage is that the electroless copper-nickel plating electrolyte described herein is ammonia-free. Many conventional electroless nickel plating electrolytes contain ammonia, and the ammonia evaporates with time, requiring continuous replenishment. Furthermore, ammonia is harmful to those who work with it, so an improved electroless copper- nickel plating bath that is free of ammonia is an advantage.

[0047] In one embodiment, the present invention includes a step of producing a three-dimensional part by injection molding, wherein the part has at least one first region to be metallized and that is formed of a first plastic and at least one second region that is not to be metallized and that is formed of a second plastic. In another embodiment, the three-dimensional part having at least one first region to be metallized and that is formed of a first plastic and at least one second region that is not to be metallized and that is formed of a second plastic is produced and subjected to the processing steps to produce a selectively metallized plastic part having the first region formed of the first plastic that is metallized and the second region formed of the second plastic that is notmetallized. It is contemplated that the three dimensional part may include two or more first regions of the first plastic and two or more second regions of the second plastic. As discussed above, the first plastic may be ABS or ABS / PC and the second plastic may be PC. Other combinations of plastics could also be used in the process described herein.

[0048] Prior to contacting at least a portion of the plastic of the outer surface of the mounted multicomponent molded plastic part with a chromic acid-free etchant, a “pre-etch” step may be carried out. The pre-etch solution leads to swelling of the polymer chains in the plastics and therefore to a better adhesion. The pre-etch solution may be an aqueous solution comprising surfactants and solvent. An example of a suitable pre-etch solution is an aqueous solution containing a blend of propylene carbonate and butyrolactone. Other solutions containing suitable surfactants and solvents that are capable of modifying the plastic surface so that it is more easily etched could also be used. The pre-etch step is not always required, but it may be used to modify the plastic surface so that it etches more easily. Suitable chromic acid-free etchants are known in the art. In one embodiment, the chromic acid-free etchant comprises a combination of acids with manganese III ions as described, for example, in U.S. Pat. No. 9,534,306 and U.S. Pat. No. 10,260,000, both to Pearson, the subject matter of each of which is herein incorporated by reference in its entirety. Contacting at least a portion of the plastic of the outer surface of the mounted multi-component molded plastic part with the etchant preferably comprises at least partially immersing the mounted component in the etchant, more preferably completely immersing the mounted component in the etchant. As described herein, the chromic acid-free etchant comprises manganese species with an oxidation state higher than 2, for example manganese sulfate. In one preferred embodiment, and the manganese species are optionally, but preferably, reduced to Mn2+. In one embodiment the etchant comprising the manganese species with an oxidation state higher than 2 are reduced to Mn2+using a neutralizer.

[0049] The contacting may be carried out at room temperature. However, the contacting is preferably carried out at elevated temperatures, for example at temperatures greater than ambient temperature, more preferably greater than 30°C, even more preferably greater than 50°C, still even more preferably greater than 60°C. Such elevated temperatures may help to provide a suitable level of etching but the temperature is also preferably less than 90°C, even more preferably less than 80°C. In one embodiment, the etchant is maintained at a temperature with the range of about 60 to about 80°C, more preferably about 65 to about 75°C,

[0050] The contacting time may vary, depending on the type of plastic to be etched. However, the contacting time is preferably at least 30 seconds, more preferably at least a minute, more preferably at least 5 minutes. In one embodiment, if the plastic to be etched is ABS, the etching time is in the range of about 5 to about 15 minutes, more preferably about 8 to about 10 minutes. In one embodiment, if the plastic to be etched is ABS / PC, the etching time is in the range of about 5 to about 25 minutes, more preferably about 10 to about 20 minutes. Of course, contacting times and temperatures may vary depending on the plastics being used. Such contacting times may provide a suitable level of etching.

[0051] Suitable activator solutions are known in the art and typically comprise a precious metal activator. The activator solution preferably comprises a precious metal colloid. More preferably, the precious metal colloid comprises a first core metal and a second metal that colloidally surrounds the core; the core metal comprises at least one metal selected from the group consisting of silver, platinum, palladium, ruthenium, and nickel with palladium being especially preferred; and the second metal comprises at least one metal selected from the group consisting of tin and lead with tin being especially preferred. The core metal is capable of catalytically activating the deposition of electroless copper or electroless nickel. Such an activator solution is particularly effective at promoting deposition of a copper-nickel layer in the subsequent electroless plating step. An example of a suitable commercially available activator is evolve™ Activator, available from MacDermid Enthone Inc.

[0052] In one embodiment, the activator comprises a palladium-tin activator. Contacting at least a portion of the etched surface of the component with the activator solution preferably comprises at least partially immersing the etched component in the activator solution, more preferably completely immersing the etched component in the activator solution. The contacting is typically carried out at ambient temperature, although elevated temperatures may be used. The contacting is preferably carried out for at least 30 seconds, more preferably at least a minute, even more preferably from 1 to 20 minutes, still even more preferably from 1 to 10 minutes.

[0053] Prior to contacting at least a portion of the etched surface of the component with the activator solution, the etched surface may be contacted with a neutralizer to reduce manganese in higher oxidation state to Mn2+. The neutralizer may contain an acid and a reducing agent, for example a combination of sulfuric acid and hydrogen peroxide. The neutralization step is typically carried out at room temperature, although elevated temperatures may be used. The contacting ispreferably carried out for at least 30 seconds, more preferably at least a minute, even more preferably from 1 to 20 minutes, still even more preferably from 1 to 10 minutes.

[0054] The plastic part may be rinsed, typically with water, between one or more steps of the process.

[0055] After contacting at least a portion of the etched surface of the component with an activator solution, at least a portion of the etched surface may be contacted with an accelerator solution. This may serve to remove colloid metal from the core catalytic metal, otherwise the catalytic metal may be shielded and may be ineffective. In other words, the accelerator solution removes the second metal from the activated surface thereby exposing the first core metal and enabling the catalytic function. Suitable accelerating solutions are known in the art. The accelerating solutions can vary widely in composition and may be acidic or alkaline. Preferably the accelerating solution is acidic and for example may comprise chloride ions in combination with organic and inorganic acids. An example of a suitable commercially available accelerator is evolve™ Accelerator 800 available from MacDermid Enthone Inc.

[0056] Contacting at least a portion of the etched surface of the component with the accelerating solution preferably comprises at least partially immersing the etched and activated component in the accelerator solution, more preferably completely immersing the etched and activated component in the accelerator solution. As discussed above, it was found that the process conditions for accelerator step must be adjusted. In a preferred embodiment, the contacting is typically carried out at a temperature within the range of about 25 to about 40°C, more preferably at a temperature of about 30 to about 35°C. The contacting is preferably carried out for at least 30 seconds, more preferably at least a minute, even more preferably from 1 to 20 minutes, still even more preferably from 1 to 10 minutes.

[0057] Electroless solutions for depositing a copper-nickel layer in accordance with the invention described herein are alkaline compositions and typically comprise: a) a source of copper ions, b) a source of nickel ions, c) a complexing agent to maintain said ions in solution, d) hypophosphite as a reducing agent; e) optionally, a reaction promoter; f) optionally, a grain refiner; andg) optionally, one or more stabilizers.

[0058] The source of the plating metal ions can be any of the metallic salts conventionally used for electroless plating, including sulfates and chlorides of nickel and copper. In one embodiment, the source of copper ions is a copper sulfate and the source of nickel ions is a nickel sulfate.

[0059] The concentration of the source of copper ions is preferably within the range of about 4 to about 25 g / L, more preferably about 6 to about 20 g / L, most preferably about 8 to about 15 g / L.

[0060] The concentration of the source of nickel ions is preferably within the range of about 2 to about 15 g / L, more preferably about 3 to about 12 g / L, most preferably about 4 to about 8 g / L.

[0061] It is important that the concentration of the source of copper ions and the concentration of the source of nickel ions are optimized in order to obtain very good selectivity and to avoid rack metallization. That is, while it may be desired to control the percent of copper in the deposit, it is imperative that the concentrations of both copper and nickel ions are carefully chosen to obtain the best result in selectivity plating a molded multi-component plastic part as describe herein.

[0062] The complexing agents used to maintain the plating metal in solution can be either a single complexing agent for copper and nickel ions dissolved in solution or a mixture of compatible complexing agents specifically formulated for the mixture of copper and nickel ions in solution. Various complexing agents known in the art for use in electroless copper and nickel may be used, however, it is desirable that the solution be at least substantially free of ammonia, preferably completely free of ammonia and therefore ammonium-containing compound are generally not preferred.

[0063] Preferred complexing agents include hydroxy substituted carboxylic acids such as gluconic acid, citric acid, sulfosalicylic acid and malic acid. Other complexing agents include amine complexing agents, such as alkanolamines.

[0064] The concentration of the complexing agent is preferably within the range of about 1 to about 50 g / L, more preferably about 2 to about 25 g / L, most preferably about 5 to about 20 g / L.

[0065] A pH adjuster may also be used in the composition of the invention to maintain pH. The pH adjuster may be a hydroxide, such as sodium hydroxide or another suitable compound that is compatible with the ingredients of the electroless solution. However, as discussed above, it is preferred that the composition be at least substantially free of ammonia and thus ammonium hydroxide is generally not preferred.

[0066] The reducing agent is a hypophosphite salt, such as sodium hypophosphite. Optionally, but preferably, the hypophosphite is used in molar excess of the plating metal. In one embodiment, the concentration of the reducing agent is in the range of about 1 to about 30 g / L, more preferably about 2 to about 25 g / L, most preferably about 10 to about 20 g / L.

[0067] The pH of the plating solution in accordance with this invention is at least 7 and preferably, when using the preferred carboxylic acid complexing agents, varies between about 8.0 and 14.0, and more preferably, between 8.0 and 11, more preferably between about 9 and about 10.5. Any pH adjustor typically used in the electroless plating is suitable although ammonium hydroxide is preferably avoided.

[0068] A reaction promoter is also added to the solution to control the plating reaction and plating rate. In one embodiment, the reaction promoter comprises compounds that contain oxy anions, such as salts of carbonates and borates, preferably alkali and alkaline earth metal salts thereof. In one embodiment, the reaction promoter comprises a carbonate, such as potassium carbonate. The concentration of the reaction promoter is preferably within the range of about 1 to about 20 g / L, more preferably about 2 to about 15 g / L, most preferably about 4 to about 10 g / L.

[0069] In addition, the electroless plating composition also preferably comprises a grain refiner, which may be a bipyridine such as 2,2'-bipyridine.

[0070] In addition, the electroless plating composition also preferably comprises one or more bath stabilizers to provide a sufficient bath lifetime and reasonable deposition rate and to control the content of any alloying materials. The stabilizer is added to avoid decomposition of the plating electrolyte and uncontrolled plate out of the metals in the electroless plating composition. Stabilizing agents include organic and / or inorganic stabilizing agents such as lead ions, cadmium ions, tin ions, bismuth ions, antimony ions and zinc ions, which can be introduced in the form of bath soluble and compatible salts such as the acetates. In one embodiment, the one or more stabilizers include bismuth ions. Suitable bismuth compounds include, for example, bismuth oxide, bismuth sulfate, bismuth sulfite, bismuth nitrate, bismuth chloride, bismuth acetate and the like. Organic stabilizers include sulfur containing compounds such as, for example, thioglycolic acid, thiodiglycolic acid, thiourea, mercaptans, sulfonates, thiocyanates, and combinations of one or more of the foregoing.

[0071] The stabilizers are typically used in small amounts such as from about 0.01 to about 20 mg / L of solution, and more often in amounts of about 0.5 to about 10 mg / L of solution. In oneembodiment, the one or more stabilizers are used in amounts greater than about 2 mg / L, preferably about 2 to about 20 mg / L. The upper limit of the concentration of the metal stabilizers is such that the deposition velocity is not reduced. In one embodiment, the stabilizer is present at a concentration up to about 15 mg / L.

[0072] Conventional nickel plating electrolytes that contain ammonia typically require a low concentration of a stabilizer to avoid skip plating (i.e., less than 5 mg / L). In contrast, the electroless copper-nickel plating electrolyte described herein can use a significantly higher concentration of the stabilizer. Even when the stabilizer exceeds 5 mg / L, the plating electrolyte exhibits high selectivity, even on parts that are hard to coat, and suppresses rack plating without inhibiting the plating electrolyte.

[0073] In one embodiment, the electroless copper-nickel plating electrolyte comprises bismuth ions and a bipyridine.

[0074] In one embodiment, the electroless copper-nickel plating electrolyte is maintained at a temperature in the range of about 25°C to about 45°C, more preferably about 30 to about 40°C while the multi-component molded plastic part is in contact with the electroless copper-nickel plating electrolyte. The inventors of the present invention have discovered that higher temperatures result in a deposit having less selectivity and greater rack metallization.

[0075] Because copper co-deposits at a faster rate than the nickel, the solution is replenished with larger concentrations of copper than either nickel to obtain uniform deposits from solution. Replenishment can be accomplished by continuously metering copper into the plating solution at a rate greater than other metallic solution components, by adding copper more frequently than the other components or by adding larger amounts of copper when the solution is replenished.

[0076] Normally, copper cannot be reduced by sodium hypophosphite in an electroless plating bath. However, in the plating electrolyte described herein, the presence of nickel in the plating electrolyte starts the autocatalytic process and provides a catalytic surface and electrons are emitted across the surface to reduce copper and nickel ions.

[0077] As described herein, one of the benefits of the process described herein is that because the electroless copper-nickel layer has a higher copper content, this layer has a correspondingly higher conductivity. As a result, it is possible to directly electroplate on the electroless copper-nickel layer, such as with an acidic copper electrolyte, and without the need for any intervening process steps such as an immersion copper treatment.

[0078] After depositing the electroless copper-nickel layer, a copper layer may be electrodeposited over the electroless copper-nickel layer. As described herein, the copper layer may be electrodeposited using an acidic copper electrolyte. The copper layer may also be electrodeposited directly onto the electroless copper-nickel layer without immersion copper, nickel strike, or any other intervening process steps.

[0079] In another embodiment, the present invention also relates generally to a selectively metallized multi-component molded plastic part comprising at least one first region formed of a first plastic and at least one second region formed of a second plastic, wherein the at least one first region formed of the first plastic is metallized with a first layer comprising a copper-nickel layer and a second layer comprising copper, wherein the second layer is formed directly on the first layer, and wherein the at least one second region formed of the second plastic is at least substantially free of metallization.

[0080] What is meant by “at least substantially free of metallization” is that less than 1% unwanted metallization occurs on the at least one second region formed of the second plastic.

[0081] In one embodiment, the plated copper-nickel layer consists essentially of about 85 to about 97 wt.% copper, about 2 to about 10 wt.% nickel, and about 1 to about 5 wt.% phosphorus, more preferably about 90 to about 95 wt.% copper, about 3 to about 7 wt.% nickel, and about 2 to about 3 wt.% phosphorus.

[0082] Moreover, because the nickel concentration is lower than in a conventional electroless nickel plating electrolyte, the consumption of nickel in the plating electrolyte is also lower. Copper metal is typically less expensive than nickel, so this reduction in nickel consumption is expected to result in a more cost-effective process as compared with conventional electroless nickel plating electrolytes.

[0083] In another embodiment, the present invention also relates generally to a multi-component molded plastic part made by the method described herein.

[0084] The component may typically comprise any plastic component that is required to be electroplated. Examples include an automotive support (e.g., automotive grilles, headlamp surrounds, door handles and decorative trim), a shower fitting support, a bathroom fitting support, household fittings and furniture fittings and electronics components (e.g., cameras, computers, telephones).

[0085] The present invention will now be described in reference to the following non-limiting examples:Examples:

[0086] Table 1 describes a general cycle for preparing a plastic part for subsequent plating thereon as used in the Examples.Table 1. General process cycle

[0087] Table 2 provides information regarding various products used in the general process cycle described in Table 1, all of which are available from MacDermid Enthone Inc.Table 2. List of products used in general process cycleComparative Example 1;

[0088] Test samples containing an ABS portion and a PC portion were etched in a conventional chromic acid etch solution for 10 minutes at 70°C followed by a reducing step. The etched test samples were rinsed and then treated in one of the activators listed below.

[0089] The test samples were then treated in one of the electroless nickel solutions identified in Table 2 or the copper-nickel plating electrolyte described below in Table 4 (Test 7). The plating conditions for the electroless plating step were of a plating time of 9 minutes at a temperature of 30°C and a pH of 8.8. Sodium hydroxide was used as a pH adjuster.

[0090] A series of four tests were performed using the above process conditions (Tests 1 to 4) as follows:Test 1: evolve™ Activator followed by Udique™ 891 Electroless NickelTest 2: UdiqueTM879 W Activator (no conditioner) followed by Udique™ 891 Electroless Nickel Test 3: evolve™ Activator followed by Copper-Nickel (Table 4, Test 7)Test 4: Udique™ 879 W Activator (no conditioner) followed by Copper-Nickel (Table 4, Test 7)

[0091] The results of Tests 1-4 are provided below in Table 9. As seen in Table 9, all of Tests 1 to 4 showed no rack metallization, demonstrating that the use of a chromic acid etch provided a good result in terms of rack metallization. However, while Tests 1 and 3 (both of which used an activator in combination with a conditioner) provided good results in terms of selectivity with both electroless nickel and electroless copper-nickel plating, a different result occurred when a more active activator was used without a conditioner. In this case, poor selectivity was observed when an electroless nickel plating electrolyte was used, although a better result was achieved when plating with an electroless copper-nickel plating electrolyte.Comparative Example 2:

[0092] Test samples containing an ABS / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1. Instead of a chromic acid etchant as used in Comparative Example 1, the test samples were treated in evolve™ Etch for 15 minutes at 70°C.

[0093] The test samples were then treated in an electroless nickel plating solution for 9 minutes at 30°C at a pH of 8.8. Sodium hydroxide was used as a pH adjuster.

[0094] A series of two tests were performed with two different activator solutions and two different electroless nickel plating solutions as follows:Test 5: Conditioner (XRD Conditioner 1153) evolve™ Activator, evolve™ electroless nickel Test 6: Udique™ 879 W Activator (no conditioner) and Udique™ 891 electroless nickel.

[0095] After the activation step and prior to the electroless nickel plating step, the test samples were contacted with an accelerator (evolve™ accelerator 800) at a temperature of 45°C for 2 minutes.

[0096] As set forth in Table 9 below, the use of the process steps described in Tests 5 and 6 resulted in little to no selectivity and did not demonstrate good results in terms of rack metallization.Example 3:

[0097] Test samples containing an ABS / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0098] An alkaline electroless copper-nickel plating electrolyte was prepared as shown in Table 4 below for Tests 7 to 12. The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide.

[0099] Tests 7 to 12 were carried in which the temperature of the electroless nickel plating electrolyte was varied between 30°C and 60°C as outlined below in Table 3. The same plating electrolyte was used in each of Tests 7 to 12.

[0100] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.Table 3. Influence of temperature on plating selectivity and rack metallization

[0101] As set forth in Table 9 below, the temperature of the plating solution had a significant effect on both the selectivity of the plating and the rack metallization. At temperatures above about 45°C (see Test 10), the quality of both started to decline and for temperatures at or above 50°C (see Tests 11 and 12), both the selectivity and rack metallization were poor. These results demonstrate that controlling temperature of the electroless copper-nickel plating electrolyte is an important factor in obtaining good selectivity and in minimizing rack metallization.Table 4: Electroless copper-nickel plating electrolyte compositionsTable 5: Electroless copper-nickel plating electrolyte compositions (continued)Table 5A: Electroless copper-nickel plating electrolyte compositions (continued)Example 4:

[0102] Test samples containing an AB S / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0103] An alkaline electroless copper-nickel plating electrolyte was prepared as shown in Table 5 for Test 13. As compared with the plating electrolyte used in Tests 7 to 12, the copper-nickel plating electrolyte used in Test 13 contained a higher concentration of nickel.

[0104] The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the copper-nickel plating electrolyte was maintained at 35°C.

[0105] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0106] As set forth in Table 9, good selectivity and minimal rack metallization were observed.Example 5:

[0107] Test samples containing an AB S / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0108] An alkaline electroless copper-nickel plating electrolyte was prepared as shown in Table 5 for Test 14. As compared with the plating electrolyte used in Tests 7 to 12, the copper-nickel plating electrolyte used in Test 14 contained a lower concentration of nickel.

[0109] The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the copper-nickel plating electrolyte was maintained at 35°C.

[0110] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0111] As set forth in Table 9, good selectivity was obtained, and no rack metallization was observed. As compared with Example 4, the lower concentration of nickel gave a better result in terms of preventing rack metallization.Example 6:

[0112] Test samples containing an AB S / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0113] An alkaline electroless copper-nickel plating electrolyte was prepared as shown in Table 5 for Tests 15 and 16.

[0114] The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the copper-nickel plating electrolyte was maintained at 35°C.

[0115] The plating process for Test 15 used evolve™ Activator in combination with XRD 1153 Conditioner. The plating process for Test 16 used Udique™ 897 W as the activator and no conditioner. Both Tests 15 and 16 used evolve™ 800 Accelerator at a concentration of 67.5 mL / L. The test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0116] As set forth in Table 9, good selectivity and no rack metallization were observed for both Test 15 and Test 16. However, Test 15, which used both a combination of a conditioner and an activator showed greater selectivity.Example 7:

[0117] Test samples containing an AB S / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0118] An alkaline electroless copper-nickel plating electrolyte was prepared as shown in Table 5 for Test 17.

[0119] The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the copper-nickel plating electrolyte was maintained at 35°C.

[0120] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator 800. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0121] As set forth in Table 9, very good selectivity and no rack metallization were observed.Comparative Example 8:

[0122] Test samples containing an AB S / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0123] An alkaline electroless nickel plating electrolyte was prepared as shown in Table 5 for Test 18. In Test 18, copper was not included in the nickel plating electrolyte composition and the amount of copper was substituted by nickel.

[0124] The nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the nickel plating electrolyte was maintained at 35°C.

[0125] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0126] As set forth in Table 9, bad selectivity and significant rack metallization were observed.Example 9:

[0127] Test samples containing an AB S / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0128] Alkaline electroless copper-nickel plating electrolytes were prepared as shown in Table 5 A for Tests 19-22. Tests 19-22 were carried out using an electroless copper-nickel plating electrolyte maintained at a temperature of 35°C. The pH was adjusted to 10.2 with sodium hydroxide. Tests 19-22 demonstrate the different result that is achieved when the concentration of nickel is changed in the plating composition and nickel sulfate concentrations between 4.5 and 11.5 g / L were used.

[0129] Plating was carried out on a test sample containing ABS / PC and PC portions. The resulting deposit on the ABS / PC portion was a grayish-pink, dull deposit.

[0130] The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the copper-nickel plating electrolyte was maintained at 35°C.

[0131] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator 800. The evolve™ Accelerator was used at a concentration of 67.5mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0132] As set forth in Table 9, the concentration of nickel in the electroless copper-nickel plating electrolyte had an effect on both selectivity and rack metallization and higher concentration of nickel in the electroless copper-nickel plating electrolyte had an adverse effect on the selectivity as well as the rack metallization. Thus, it can be seen that control of the nickel concentration in the copper-nickel plating electrolyte is important in order to achieve high selectivity and no rack metallization.Example 10:

[0133] Test samples containing an ABS / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0134] Alkaline electroless copper-nickel plating electrolytes were prepared as shown in Table 5 A for Tests 23 and 24. Tests 23 and 24 were carried out using an electroless copper-nickel plating electrolyte maintained at a temperature of 35°C. The pH was adjusted to 10.2 with sodium hydroxide. Tests 23 and 24 demonstrate the different result that is achieved when the concentration of copper is reduced in the plating.

[0135] Plating was carried out on a test sample containing ABS / PC and PC portions. The resulting deposit on the ABS / PC portion was a grayish-pink, dull deposit.

[0136] The copper-nickel plating electrolyte was adjusted to a pH of 10.2 with sodium hydroxide and the temperature of the copper-nickel plating electrolyte was maintained at 35°C.

[0137] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator for 1.5 minutes at a temperature of 30°C.

[0138] As set forth in Table 9, Tests 23 and 24 demonstrate the different result that is achieve when the concentration of copper was reduced in the plating composition. As seen in Table 8, when the amount of copper was reduced, the selectivity was poor and signification rack metallization was observed. Thus, it was seen that a concentration of copper sulfate x 5H2O of atleast about 6 g / L, more preferably at least about 8 g / L was necessary in order to achieve a good result in terms of selectivity and rack metallization.

[0139] Table 6 presents the results for % nickel and the thickness of the copper-nickel layer for each of Tests 19-24. As set forth in Table 6, Tests 22-24 which had the highest concentration of nickel in the copper-nickel layer exhibited reduced or bad selectivity, even though the thickness of the copper-nickel layer was higher.Table 6. % Nickel and Thickness results for Tests 19-24Example 11:

[0140] Test samples containing an ABS / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0141] An alkaline electroless copper-nickel plating electrolyte was prepared as shown in Table 7 below for Tests 25 to 29. The copper-nickel plating electrolyte was adjusted to a pH of 10.5 with sodium hydroxide and the temperature was maintained at 35°C.

[0142] As compared with plating electrolyte used in Tests 7 to 12, the concentration of the stabilizers in the plating electrolyte used in Tests 25 to 29 was varied as outlined in Table 7 below.

[0143] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0144] As set forth in Table 9, the concentration of the stabilizer had a significant effect on the selectivity, rack metallization, plating speed, and skip plating. As the concentration increased from 2.5 to 15 mg / L, the plating speed decreased while the selectivity and rack metallization improved.However, skip plate avoidance steadily decreased, indicating that more skip plating occurred and, at a concentration of 20 mg / L, the plating electrolyte was completely inhibited, and no plating was observed.Table 7. Influence of a stabilizer on plating selectivity and rack metallizationComparative Example 12:

[0145] Test samples containing an ABS / PC portion and a PC portion were treated in accordance with the general plating cycle outlined in Table 1, which included the use of evolve™ Etch for 15 minutes at 70°C to produce a pink, satin-matte deposit on surfaces of the test panel.

[0146] An alkaline electroless nickel plating electrolyte was prepared using Udique 891, a conventional plating electrolyte that contains ammonia. The alkaline electroless nickel plating electrolyte was maintained at a pH of 8.8 and a temperature of 35°C.

[0147] The alkaline electroless nickel plating electrolyte further contained varying concentrations of bismuth as a stabilizer at concentrations of 0.5 mg / L, 3 mg / L, and 5 mg / L for Tests 30, 31, and 32, respectively.

[0148] The plating process used evolve™ Activator in combination with XRD 1153 Conditioner and evolve™ 800 Accelerator. The evolve™ Accelerator 800 was used at a concentration of 67.5 mL / L and the test samples were contacted with the evolve™ Accelerator 800 for 1.5 minutes at a temperature of 30°C.

[0149] As set forth in Table 9, the alkaline electroless nickel plating electrolyte is more sensitive to the amount of stabilizer added. As the concentration of the stabilizer approaches only 5 mg / L, the plating speed and skip plate avoidance significantly decreased, demonstrating that desired areas are not plated (i.e., skip plating) the plating electrolyte is completely inhibited at concentrations above 5 mg / L.

[0150] Table 8 presents the results for selectivity and rack metallization for each of Tests 1 to 24 as described in the examples above. Table 8 further presents the results for selectivity, rack metallization, plating speed, and skip plate avoidance for each of Tests 25 to 32 as described in the examples above. Table 9 depicts the different ratings regarding selectivity between the two different plastics of the multi-component molded plastic part and the degree of rack plating that is observed on the plating rack during the plating process for each of Tests 1 to 24. Table 9 further depicts the different ratings regarding selectivity between the two different plastics of the multicomponent molded plastic part, the degree of rack plating, plating speed, and skip plate avoidance that is observed on the plating rack during the plating process for each of Tests 25 to 32.Table 8. Rating of levels of selectivity and rack platingTable 9. Test results for selectivity and rack metallization

[0151] Finally, it should also be understood that the following claims are intended to cover all of the generic and specific features of the invention described herein and all statements of the scope of the invention that as a matter of language might fall there between.ADDITIONAL EMBODIMENTSClause 1 : A method of preparing a multi-component molded plastic part for electroplating thereon, wherein the multi-component molded plastic part comprises at least one first region to be metallized formed of a first plastic and at least one second region that is not to be metallized formed of a second plastic, the method comprising the steps of: a. contacting the multi-component molded plastic part with a chromic acid-free etchant to etch selected surfaces of the multi-component molded plastic part, wherein the chromic acid-free etchant comprises manganese species with an oxidation state higher than 2; b. optionally, reducing the manganese species with the oxidation species higher than 2 to Mn2+;c. optionally, conditioning the selected surfaces of the multi-component molded plastic part with a conditioner; d. activating the selected surfaces of the multi-component molded plastic part with a precious metal colloid activator comprising a first core metal and a second metal; e. contacting the activated surfaces of the multi-component molded plastic part with an accelerator, wherein the accelerator removes the second metal from the treated surfaces; and f. depositing an electroless plating layer on the selected surfaces of the multicomponent molded plastic part with an electroless plating electrolyte comprising nickel and copper; wherein an electroless copper-nickel layer is deposited on the first region formed of the first plastic and does not substantially deposit on the second region formed of the second plasticClause 2: The method according to clause 1, wherein the first plastic comprises a copolymer of acrylonitrile butadiene styrene (ABS) or ABS combined with polycarbonate (ABS / PC) and the second plastic comprises polycarbonate (PC).Clause 3: The method according to clause 1 or clause 2, wherein the first plastic consists of either a copolymer of acrylonitrile butadiene styrene (ABS) or ABS combined with polycarbonate (ABS / PC) and the second plastic consists of polycarbonate (PC).Clause 4: The method according to any of the preceding clauses, further comprising the step of electrodepositing a copper layer over the electroless copper-nickel layer deposited on the first region formed of the first plastic.Clause 5: The method according to clause 4, wherein the copper layer is electrodeposited using an acidic copper electrolyte, optionally wherein the copper layer is electrodeposited directly on the electroless copper-nickel layer without any intervening process steps.Clause 6: The method according to any of the preceding clauses, further comprising the step of a modifying the plastic surface with a pre-etchant prior to the etching step, optionally wherein the pre-etchant is an aqueous solution comprising surfactants and at least one solvent.Clause 7: The method according to any of the preceding clauses, wherein the electroless copper- nickel plating electrolyte comprises:a. a source of copper ions; b. a source of nickel ions; c. a complexing agent to maintain said ions in solution; d. hypophosphite as a reducing agent; e. optionally, a reaction promoter; f. optionally, a grain refiner; and g. optionally, one or more stabilizers.Clause 8: The method according to any of the preceding clauses, wherein the electroless coppernickel plating electrolyte is maintained a temperature in the range of about 30°C to about 45°C while the multi-component molded plastic part is in contact with the electroless copper-nickel plating electrolyte.Clause 9: The method according to any of the preceding clauses, wherein the multi-component molded plastic part is brought into contact with the electroless copper-nickel plating electrolyte for about 1 to about 15 minutes.Clause 10: The method according to clause 7, wherein the electroless copper-nickel plating electrolyte is maintained a temperature in the range of about 30°C to about 40°C to while the multicomponent molded plastic part is in contact with the electroless copper-nickel plating electrolyte. Clause 11: The method according to clause 7, wherein the electroless copper-nickel plating electrolyte further comprises one or more stabilizers, wherein the one or more stabilizers is selected from the group consisting of bismuth ions, antimony ions, zinc ions, and sulfur containing compounds.Clause 12: The method according to any of the preceding clauses wherein the electroless copper- nickel plating electrolyte is maintained at a pH in the range of about 8 to about 11 or about 9 to about 10.5.Clause 13: The method according to any of the preceding clauses, wherein the accelerator is maintained at a temperature of 25 to about 40°C, more preferably at a temperature of about 30 to about 35°C while the two component molded plastic part is in contact with the accelerator.Clause 14: The method according to clause 11, wherein the one or more stabilizers comprise bismuth ions.Clause 15: The method according to clauses 11 or 14, wherein the one or more stabilizers are present in the copper-nickel plating electrolyte at a concentration ranging from about 0.01 to about 20 mg / L.Clause 16: The method according to clauses 11 or 14-15, wherein the one or more stabilizers are present in the copper-nickel plating electrolyte at a concentration in the range of about 2 to about 20 mg / L.Clause 17: A multi-component molded plastic part made by the method of any of the preceding clauses.Clause 18: A selectively metallized multi-component molded plastic part comprising at least one first region formed of a first plastic and at least one second region formed of a second plastic, wherein the at least one first region formed of the first plastic is metallized with a first layer comprising a copper-nickel layer and a second layer comprising copper, wherein the second layer is formed directly on the first layer, and wherein the at least one second region formed of the second plastic is at least substantially free of metallization.Clause 19: The multi-component molded plastic part according to clause 17, wherein the copper- nickel layer consists essentially of about 85 to about 97 wt.% copper, about 2 to about 10 wt.% nickel, and about 1 to about 5 wt.% phosphorus.

Claims

WHAT IS CLAIMED IS:

1. A method of preparing a multi-component molded plastic part for electroplating thereon, wherein the multi-component molded plastic part comprises at least one first region to be metallized formed of a first plastic and at least one second region that is not to be metallized formed of a second plastic, the method comprising the steps of: a. contacting the multi-component molded plastic part with a chromic acid-free etchant to etch selected surfaces of the multi-component molded plastic part, wherein the chromic acid-free etchant comprises manganese species with an oxidation state higher than 2; b. optionally, reducing the manganese species with the oxidation species higher than 2 to Mn2, c. optionally, conditioning the selected surfaces of the multi-component molded plastic part with a conditioner; d. activating the selected surfaces of the multi-component molded plastic part with a precious metal colloid activator comprising a first core metal and a second metal; e. contacting the activated surfaces of the multi-component molded plastic part with an accelerator, wherein the accelerator removes the second metal from the treated surfaces; and f. depositing an electroless plating layer on the selected surfaces of the multicomponent molded plastic part with an electroless plating electrolyte comprising nickel and copper; wherein an electroless copper-nickel layer is deposited on the first region formed of the first plastic and does not substantially deposit on the second region formed of the second plastic.

2. The method according to claim 1, wherein the first plastic comprises a copolymer of acrylonitrile butadiene styrene (ABS) or ABS combined with polycarbonate (ABS / PC) and the second plastic comprises polycarbonate (PC).

3. The method according to claim 1, wherein the first plastic consists of either a copolymer of acrylonitrile butadiene styrene (ABS) or ABS combined with polycarbonate (ABS / PC) and the second plastic consists of polycarbonate (PC).

4. The method according to any of claims 1 -3, further comprising the step of electrodepositing a copper layer over the electroless copper-nickel layer deposited on the first region formed of the first plastic.

5. The method according to claim 4, wherein the copper layer is electrodeposited using an acidic copper electrolyte, optionally wherein the copper layer is electrodeposited directly on the electroless copper-nickel layer without any intervening process steps.

6. The method according to any of claims 1-3, further comprising the step of a modifying the plastic surface with a pre-etchant prior to the etching step, optionally wherein the preetchant is an aqueous solution comprising surfactants and at least one solvent.

7. The method according to any of claims 1-3, wherein the electroless-copper nickel plating electrolyte comprises: a. a source of copper ions, b. a source of nickel ions, c. a complexing agent to maintain said ions in solution, d. hypophosphite as a reducing agent; e. optionally, a reaction promoter; f. optionally, a grain refiner; and g. optionally, one or more stabilizers.

8. The method according to any of claims 1-3, wherein the electroless copper-nickel plating electrolyte is maintained a temperature in the range of about 30°C to about 45°C while the multi-component molded plastic part is in contact with the electroless copper-nickel plating electrolyte.

9. The method according to any of claims 1-3, wherein the multi-component molded plastic part is brought into contact with the electroless copper-nickel plating electrolyte for about 1 to about 15 minutes.

10. The method according to claim 7, wherein the electroless copper-nickel plating electrolyte is maintained a temperature in the range of about 30°C to about 40°C to while the multicomponent molded plastic part is in contact with the electroless copper-nickel plating electrolyte.

11. The method according to claim 7, wherein the electroless copper-nickel plating electrolyte further comprises one or more stabilizers, wherein the one or more stabilizers is selected from the group consisting of bismuth ions, antimony ions, zinc ions, and sulfur containing compounds.

12. The method according to any of claims 1-3, wherein the electroless copper-nickel plating electrolyte is maintained at a pH in the range of about 8 to about 11 or about 9 to about 10.5.

13. The method according to any of claims 1-3, wherein the accelerator is maintained at a temperature of 25 to about 40°C, more preferably at a temperature of about 30 to about 35°C while the two component molded plastic part is in contact with the accelerator.

14. The method according to claim 11, wherein the one or more stabilizers comprise bismuth ions.

15. The method according to claim 14, wherein the one or more stabilizers are present in the copper-nickel plating electrolyte at a concentration ranging from about 0.01 to about 20 mg / L.

16. The method according to claim 15, wherein the one or more stabilizers are present in the copper-nickel plating electrolyte at a concentration in the range of about 2 to about 20 mg / L.

17. A multi-component molded plastic part made by the method of any of claims 1-3.

18. A selectively metallized multi-component molded plastic part comprising at least one first region formed of a first plastic and at least one second region formed of a second plastic, wherein the at least one first region formed of the first plastic is metallized with a first layer comprising a copper-nickel layer and a second layer comprising copper, wherein the second layer is formed directly on the first layer, and wherein the at least one second region formed of the second plastic is at least substantially free of metallization.

19. The multi-component molded plastic part according to claim 17, wherein the copper-nickel layer consists essentially of about 85 to about 97 wt.% copper, about 2 to about 10 wt.% nickel, and about 1 to about 5 wt.% phosphorus.

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