PREVENTION OF UNWANTED PLATING ON RACK COATINGS FOR ELECTRODEPOSITION

A support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising iodine-treated and/or bromine-treated plastic.

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Description

The invention relates to a support for supporting a component to be plated in a chromic acid-free plating process, a plating apparatus for use in a chromic acid-free plating process, a method of treating a support for supporting a component to be plated in a chromic acid-free plating process, a process for plating a component, and the use of an iodine and/or bromine pre-treatment on a support for supporting a component to be plated.

Plating on plastics (POP) is a technique that has wide-ranging applications in, for example, the automotive industry and shower and bathroom fittings. The most common substrate for plating is a copolymer of acrylonitrile, styrene and butadiene which is known as ABS. This 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 to make ABS/PC. In order to plate these components, they are mounted on metal racks in order to transmit the plating current to the components after the initial metallisation stage. The metal plating racks are coated with a PVC plastisol coating in order to prevent the whole of the rack from plating.

The plating process for ABS involves the stages of etching the plastic to roughen the surface so that it provides good adhesion during the subsequent plating stages and renders the surface sufficiently hydrophilic to be fully wetted when immersed in aqueous solutions. Following the etching stage, the non-conducting ABS needs to be initially metallised with a thin layer of nickel or copper in order to render it electrically conductive for the subsequent plating operation. This is achieved by immersing the plating racks holding the ABS components in an aqueous solution of a catalyst (typically a palladium colloid) which deposits a thin layer of the catalyst on the plastic surface. This then acts as a catalyst for an electroless nickel or copper plating process that produces a thin metallic layer on the ABS components. Such aqueous solutions of catalysts are known as activator solutions, and plastic surfaces treated in such baths are known as ‘activated’ surfaces.

The initial etching stage for the plating of ABS has traditionally been a solution of chromic acid and sulphuric acid which oxidises (primarily) the polybutadiene phase of the ABS to produce the necessary roughening of the plastic. Chromic acid solution is highly penetrating and some of it is absorbed by the PVC plastisol material of the rack coatings. Following the subsequent 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 ABS components are immersed in the electroless nickel or copper solution, the catalyst adsorbed on the ABS components catalyses the deposition of copper or nickel onto the components, but due to the presence of chromic acid on the PVC plastisol on the rack coatings, no nickel or copper is deposited on the rack coatings.

Chromic acid is a category 1 carcinogen and is subject to increasing legislative pressure. Its use is currently being phased out in Europe. At present it can only be used for a few authorised applications and even this limited usage is likely to be further restricted to the point of elimination.

Recently, a new way of etching ABS plastic has been developed using a combination of acids with manganese III ions (see, for example, U.S. Pat. No. 9,534,306B2 and US 10260000B2 to Pearson, the enclosures of which are hereby incorporated by reference). However, the manganese based etches do not inhibit the palladium colloid attached to PVC plastisol coatings effectively enough to prevent the deposition of nickel or copper during the electroless deposition stage of the POP process. Several patents have been produced detailing compounds that can be used to treat the PVC rack coatings to prevent this issue (for example EP3059277B1 to Noffke, U.S. Pat. No. 9,506,150B2 to Weitershaus, U.S. Pat. No. 9,181,622B2 to Middeke and the applications US2015233011A1 to Herdman and US2019112712A1 to Dalbin, the enclosures of which are hereby incorporated by reference). Most of the compounds currently being used are organo-sulfur compounds. Whilst these are effective at preventing the deposition of nickel or copper during the electroless plating stage, they can cause a surprising issue during the electroplating stages. This problem is that even though there is no detectable nickel or copper on the PVC plastisol coatings after immersion in the electroless process, the racks subsequently become covered in copper during the acid copper plating stage that follows the initial metallisation of the ABS components. Without wishing to be bound by theory, it is considered that this is most likely due to the reaction of copper ions with the adsorbed organo-sulfur compounds on the PVC coatings leading to the formation of copper sulphide. This is a p-type semiconductor with a high specific conductivity and, without being bound by theory, it is considered that this is the main reason for the tendency of the plating racks to become covered with copper. Therefore, there is a need for an improved method for inhibiting plating on PVC rack coatings during the plating of ABS and ABS/PC when using processing technology that does not involve the use of chromic acid.

WO2015/150156A1 relates to a composition and process for metallizing non-conductive plastic surfaces. WO2013/135862A2 relates to a process for metallizing non-conductive plastic surfaces. The processes of both documents use iodate (IO3−) solutions to pre-treat a plating rack. Since no reducing agent is present in the solutions, the iodate ions remain as iodate ions and do not form iodine, i.e. I2. The effect of such a pre-treatment is described as leading “to special protection of the plastic casing of the racks against metal deposition”. One problem with such processes is that it is not possible to confirm whether or not the rack has been pre-treated because there is no visual change in the rack following the pre-treatment.

Accordingly, one has to either perform the pre-treatment step every time the deposition process is carried out, or alternatively accept the risk that the pre-treatment either has not been performed or has worn off/become ineffective.

The present invention seeks to tackle at least some of the problems associated with the prior art or at least to provide a commercially acceptable alternative solution thereto. In particular, the present invention seeks to provide an improved support for use in a chromic acid-free plating process.

In a first aspect, the present invention provides a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising iodine-treated and/or bromine-treated plastic.

The inventors have surprisingly found that when a component is mounted on the support during a chromic acid-free plating process, there may be substantially no deposition of copper or nickel on the support during an electroless deposition stage, and there may also be substantially no deposition on the support during a subsequent electroplating stage. Without being bound by theory, it is considered that, in contrary to organosulfur-treated supports, the contact surface of the support of the present invention does not become significantly activated such that it becomes plated in an acid copper electroplating process.

While iodate-treated plastics have been described in the prior art as being resistant to metal deposition, it is surprising that this effect is also exhibited by iodine-treated and/or bromine-treated plastics. This is because iodate and iodine are chemically very different—iodate is an ionic species (IO3−), containing iodine atoms in the oxidation state of +5 combined with oxygen atoms, whereas iodine is a covalent, species (I2) containing only iodine atoms in the elemental state (oxidation state of zero).

Each aspect or embodiment as defined herein may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular, any features indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

When introducing elements of the present disclosure or the preferred embodiments(s) thereof, the supports “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The term “consisting of” is intended to mean that no other elements may be present other than those listed. The term “consisting essentially of” is intended to mean that no other elements may be present other than those listed unless the other elements do not materially affect the basic and novel characteristics of the invention.

The support is for use in a chromic acid-free plating process, preferably a plating-on-plastic (“POP”) process. The plating process is substantially free of chromic-acid, in particular substantially free of chromic-acid during the etching step of the plating process.

The contact surface of the support is the (outer) surface that comes into contact with the etching and plating solutions during a typical treatment process. Typically, substantially the entire contact surface of the support comprises iodine-treated and/or bromine-treated plastic, more typically the entire contact surface of the support.

The contact surface of the support comprises (or consists essentially of or consists of) iodine-treated and/or bromine-treated plastic. By “treated” it is meant that the plastic contains iodine and/or bromine, typically by being contacted with a solution of iodine and/or bromine (i.e. I2 and/or Br2). Without being bound by theory, it is considered that as a result of the contacting, the iodine and/or bromine (i.e. I2 and/or Br2) infuses into the surface of the plastic. In other words, the iodine-treated and/or bromine-treated plastic may be iodine-infused and/or bromine-infused plastic (i.e. molecular iodine/I2-infused and/or molecular bromine/Br2-infused plastic), respectively. Infusion of iodine and/or bromine into the plastic may be observed by a colour change in the plastic, typically brown for iodine-infused plastic and orange for bromine-infused plastic. Since the use of iodine and/or bromine changes the colour of the plastic, in contrast to the use of iodate solutions in conventional processes, the present invention may enable a user to identify whether or not the plastic has been treated. Over time and/or extended use, the effect of the iodine and/or bromine treatment may be reduced, and the colour of the plastic may change accordingly, allowing an operator to identify when further treatment to the support may be required.

The contact surface comprises iodine-treated and/or bromine-treated plastic. The contact surface preferably comprises iodine-treated plastic. While still effective, bromine is not as persistent on the surface of the plastic as iodine.

The plastic preferably comprises (or consists essentially of or consists of) PVC, more preferably PVC plastisol. PVC, or polyvinyl chloride, is produced by polymerisation of the vinyl chloride monomer. PVC plastisol comprises a suspension of PVC particles in a liquid plasticiser. Iodine and/or bromine treatment of such materials may be particularly effective at inhibiting plating on such materials during electroless plating and/or electroplating.

The support preferably comprises metal at least partially coated with the plastic. The presence of the metal may enable transmittance of a plating current to a component supported by the support during an electroplating process. The metal preferably comprises copper and/or iron alloys. The metal may function as an electrode (cathode or anode) during an electroplating process. Specifically, the support for holding the components is typically made of metal in order to transmit electric current to the components during electroplating. The components are typically held in place on the support by spring contacts or clips, hereafter referred to as the support clips.

In order to transmit current, these support clips necessarily 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, in order to prevent the entire support from being electroplated. This coated surface is hereafter referred to as the support contact surface. Typically, the part of the support where a contact is made to the electrical supply for supplying the electroplating current, typically at the top of the support, is not coated since it is not immersed in the treatment solutions.

The support preferably comprises a plating rack. A plating rack is particularly suitable for supporting one or more components during a plating process. Suitable shapes and configurations of racks are known in the art. The rack may comprise, for example, one or more hooks or support clips to support a component during a plating process. The rack may comprise a cathode and/or anode for use in an electroplating process.

In a further aspect, the present invention comprises a plating apparatus for use in a chromic acid-free plating process, the plating apparatus comprising a plating vessel having one or more supports for supporting a component to be plated, the one or more supports having a contact surface comprising iodine-treated and/or bromine-treated plastic.

For the avoidance of doubt, the advantages and preferable features of other aspects of the invention apply equally to this aspect.

The support may be the support described herein.

The plating vessel is typically of a suitable shape and of suitable dimensions to contain a component to be plated during a plating process. Such plating vessels are known in the art. The inner surface, i.e. contact surface, of the vessel is typically substantially inert to the etching solutions and plating solutions used in the plating process.

In a further aspect, the present invention provides a method of treating a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic, the method comprising:

    • providing a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic;
    • providing an aqueous solution comprising one or both of iodine and bromine;
    • and contacting at least a portion of the plastic of the contact surface of the support with the aqueous solution.

For the avoidance of doubt, the advantages and preferable features of other aspects of the invention apply equally to this aspect.

Similar to the first aspect, when the support is used during a chromic-acid free plating process, there may be substantially no deposition of copper or nickel on the support during a subsequent electroless deposition stage, and there may also be substantially no deposition on the support during a subsequent electroplating stage.

The treatment may result in the support described herein. The support may comprise, for example, a plating rack.

The plastic contact surface of the support may come into contact with a component to be plated during plating, and may come into contact with the etching and/or plating solutions used in the plating process.

The aqueous solution comprises one or both of iodine and bromine, i.e. molecular iodine (I2) and molecular bromine (Br2).

Contacting at least a portion of the plastic of the contact surface of the support with the aqueous solution typically comprises at least partially immersing the support in the aqueous solution, more typically completely immersing the support in the aqueous solution.

The contacting may be carried out, for example, at between ambient temperature and 100° C. Since ambient temperatures perform adequately, it is preferred to carry out the method at ambient temperatures so as to reduce costs and to improve safety.

The aqueous solution preferably comprises iodine. While still effective, bromine is not as persistent on the surface of the plastic as iodine.

The aqueous solution preferably comprises, but is not limited to, 0.005 to 0.1 M iodine, more preferably from 0.01 to 0.05 M iodine. Use of such iodine concentrations is particularly effective at inhibiting plating on the support during a plating process.

The aqueous solution preferably comprises iodide ions. Iodine (I2) is not particularly soluble in water. The presence of iodide ions may increase the solubility of iodine in the aqueous solution. For example, the presence of iodide ions may enable the formation of an aqueous solution containing up to 12% iodine. The iodide may be introduced into the aqueous solution in the form of, for example, potassium iodide.

The molar ratio of iodide ions to iodine in the aqueous solutions is preferably at least 1:1, more preferably at least 1.5:1, even more preferably at least 2:1. Such ratios may enable the aqueous solution to contain a favourably high amount of iodine.

Alternatively, other suitable means of increasing the iodine solubility could be applied, for example introducing a co-solvent in an effective amount to make the desired concentration of iodine soluble. Suitable solvents are numerous and may include, but would not be limited to, alcohols, glycols and alkylene carbonates.

The step of providing the aqueous solution preferably comprises contacting iodide ions with iodate ions in aqueous solution. From a commercial point of view, it is not desirable to dissolve iodine in, for example, potassium iodide solution, so as to provide both the iodine and iodide ions in the aqueous solution. Advantageously, contacting the iodide ions with iodate ions results in generation of the iodine in situ according to the following chemical reaction:


IO3−+5I−+6H+→3H2O+3I2

As an alternative to iodate ions, other oxidising agents that are capable of oxidising iodide ions to iodine could be used; for example persulfate ions, nitrate ions or hydrogen peroxide could be used. The invention is not limited by the type of oxidising agent used to oxidise the iodide ions to iodine. The iodide ions are preferably typically in excess of the oxidising agent.

When the aqueous solution comprises bromine, the bromine may also be generated in situ using a corresponding bromate/bromide reaction.

The support is preferably contacted with the aqueous solution for at least 10 seconds, more preferably at least 30 seconds, even more preferably from 1 to 10 minutes, still even more preferably from 1 to 5 minutes. Such contacting times may result in the support being particularly resistant to plating. Longer contacting times may result in only a negligible improvement in plating resistance.

The plastic of the contact surface of the support preferably comprises (or consists essentially of or consists of) PVC, more preferably PVC plastisol. Iodine and/or bromine treatment of such materials may be particularly effective at inhibiting plating on such materials during electroless plating and/or electroplating.

The plating process preferably comprises plating on ABS polymer and/or ABS/PC polymer. Such plating processes are particularly susceptible to causing plating on other plastic supports used in the process, such as plastic supports. ABS, or “acrylonitrile butadiene styrene”, has the chemical formula (C8H8)x·(C4H6)y(C3H3N)z) and is a common thermoplastic polymer known in the art. ABS/PC comprises a blend of acrylonitrile butadiene styrene and polycarbonate.

In a further aspect, the present invention provides a method of manufacturing the support described herein, the method comprising the method of treating described herein.

For the avoidance of doubt, the advantages and preferable features of other aspects of the invention apply equally to this aspect.

In a further aspect, the present invention provides a process for plating a component, the process comprising:

    • providing a component to be plated, the component having an outer surface comprising a plastic;
    • providing a plating apparatus comprising a plating vessel having one or more supports for supporting a component to be plated, the one or more supports having a contact surface comprising iodine-treated and/or bromine-treated plastic;
    • mounting the component on a support of the plating apparatus to provide a mounted component;
    • contacting at least a portion of the plastic of the outer surface of the mounted component with an electrolyte to at least partially etch the plastic to form an etched surface of the component, the electrolyte being substantially free of chromic acid;
    • contacting at least a portion of the etched surface of the component with an activator solution to form an activated surface of the component; and
    • contacting at least a portion of the activated surface of the component with an electroless nickel solution or an electroless copper solution to form a plated surface of the component.

For the avoidance of doubt, the advantages and preferable features of other aspects of the invention apply equally to this aspect.

The plating apparatus may comprise the plating apparatus as described herein. The support may comprise the support as described herein.

Prior to contacting at least a portion of the plastic of the outer surface of the mounted component with an electrolyte, a “pre-etch” step may be carried out. This may involve, for example, contacting at least a portion of the plastic of the outer surface of the mounted component with an aqueous solvent blend containing propylene carbonate and butyrolactone. Such a pre-etch step is not always required, but it may modify the plastic surface so that it etches more easily.

Suitable chromic-acid free electrolytes are known in the art. Contacting at least a portion of the plastic of the outer surface of the mounted component with the electrolyte preferably comprises at least partially immersing the mounted component in the electrolyte, more preferably completely immersing the mounted component in the electrolyte. 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. To avoid loss of electrolyte, the contacting is preferably carried out at a temperature of less than 100° C., more preferably less than 90° C., even more preferably less than 80° C. The contacting is preferably carried out for at least 30 seconds, more preferably at least a minute, even more preferably at least 5 minutes, still even more preferably from 1 to 30 minutes, still even more preferably from 5 to 20 minutes. Such contacting times may provide a suitable level of etching.

Suitable activator solutions are known in the art. 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.

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 an acid, for example hydrochloric acid. This is because typical activators comprise colloids that sometimes exhibit limited stability in water. If the wet plastic surface is immersed directly into the colloid solution, the colloid at the plastic surface may become unstable.

Suitable electroless nickel and electroless copper solutions are known in the art. Typical electroless solutions comprise ions of nickel or copper together with a reducing agent such as, for example, a hypophosphite reducing agent. Contacting at least a portion of the activated surface of the component with an electroless nickel solution or an electroless copper solution preferably comprises at least partially immersing the activated component in the electroless nickel solution or the electroless copper solution, more preferably completely immersing the activated component in the electroless nickel solution or the electroless copper solution.

The component is typically rinsed, more typically in water, after being contacted with the electrolyte and/or activator solution and/or the electroless nickel solution and/or the electroless copper solution and prior to the next step.

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).

The iodine-treated and/or bromine-treated plastic preferably comprises (or consists essentially of or consists of, excluding the iodine and/or bromine) PVC, more preferably PVC plastisol.

The plastic of the outer surface of the component preferably comprises (or consists essentially of or consists of) ABS and/or ABS/PC.

The etching electrolyte may be any suitable etching electrolyte that is substantially free of chromium (VI) and may include, for example, permanganate ions or other strong oxidising agent. A preferred electrolyte comprises manganese (III) ions, preferably in a solution of from 9 to 15 molar sulphuric or phosphoric acid. Such an electrolyte is particularly effective at etching the plastic without the use of chromic acid.

The activator solution preferably comprises a precious metal colloid. More preferably, the precious metal colloid comprises a first core metal and a second colloid metal that colloidally surrounds the core; the core metal comprises at least one metal selected from the group consisting of silver, platinum, palladium and nickel with palladium being especially preferred; and the second colloid 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 nickel or copper in the subsequent electroless plating step. An example of a suitable commercially available activator is Evolve Activator by MacDermid Enthone.

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 accelerating 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 post-activator treatment removes the second colloid 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 by MacDermid Enthone.

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. The contacting is typically carried out at elevated temperature (for example 50° C.) although ambient temperatures or higher 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.

In a preferred embodiment, the process further comprises electroplating the plated surface of the component, wherein the support comprises metal at least partially coated with the iodine-treated and/or bromine-treated plastic. As discussed above, the presence of the metal may enable transmittance of a plating current to the component during the electroplating process. The electroplating preferably comprises copper electroplating.

In a further aspect, the present invention provides a component plated according to the process described herein.

For the avoidance of doubt, the advantages and preferable features of other aspects of the invention apply equally to this aspect.

In a further aspect, the present invention provides use of an iodine and/or bromine pre-treatment on a support for supporting a component to be plated, the use to inhibit plating thereon during a chromic acid-free plating process, the support having a contact surface comprising plastic.

For the avoidance of doubt, the advantages and preferable features of other aspects of the invention apply equally to this aspect.

The invention will now be described with reference to the following non-limiting drawings, in which:

FIG. 1 shows a schematic of an example of a support according to the present invention.

FIG. 2 shows a cross section of part of the support of FIG. 1 along the line A-B.

FIG. 3 shows a schematic of an example of a plating apparatus according to the present invention.

FIG. 4 shows a flow chart of an example of a method according to the present invention.

FIG. 5 shows a flow chart of an example of a process according to the present invention.

Referring to FIGS. 1-3, there is depicted an example of a support (plating rack) 1 for use in a chromic acid-free plating process according to the present invention. The rack comprises a number of hooks or support clips 2 onto which a component to be plated may be mounted during a plating process. The support has a contact surface comprising iodine-treated and/or bromine-treated plastic 3. The interior of the support may comprise metal 4. At least a portion of the metal 4 of the support clips 2 is uncoated with the iodine-treated and/or bromine-treated plastic 3 so that it is capable of transmitting an electrical current to the component during plating. FIG. 3 shows a plating apparatus 5 for use in a chromic acid-free plating process, the plating apparatus 5 comprising a plating vessel 6 having one or more supports 1 having a contact surface comprising iodine-treated and/or bromine-treated plastic 3.

Referring to FIG. 4, there is shown a method 7 of treating a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic, the method comprising:

    • i. providing a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic;
    • ii. providing an aqueous solution comprising one or both of iodine and bromine; and
    • ii. contacting at least a portion of the plastic of the contact surface of the support with the aqueous solution.

Referring to FIG. 5, there is shown a process 8 for plating a component, the process comprising:

    • a. providing a component to be plated, the component having an outer surface comprising a plastic;
    • b. providing a plating apparatus comprising a plating vessel having one or more supports for supporting a component to be plated, the one or more supports having a contact surface comprising iodine-treated and/or bromine-treated plastic;
    • c. mounting the component on a support of the plating apparatus to provide a mounted component;
    • d. contacting at least a portion of the plastic of the outer surface of the mounted component with an electrolyte to at least partially etch the plastic to form an etched surface of the component, the electrolyte being substantially free of chromic acid;
    • e. contacting at least a portion of the etched surface of the component with an activator solution to form an activated surface of the component; and
    • f. contacting at least a portion of the activated surface of the component with an electroless nickel solution or an electroless copper solution to form a plated surface of the component.

The process optionally further comprises:

    • g. electroplating the plated surface of the component, and wherein the support comprises metal at least partially coated with the iodine-treated and/or bromine-treated plastic.

The invention will now be described in relation to the following non-limiting examples. All of the examples used the same piece of PVC plastisol coating.

Example 1 (Comparative Example)

A plating rack with a coating of PVC plastisol was treated using the following sequence (rinse stages omitted for brevity):

    • 1. Immersion in an aqueous solvent blend containing 100 ml/l of propylene carbonate and 50 ml/l of butyrolactone at 35° C. for 3 minutes
    • 2. Etching in a chromium-free etchant based on the teachings on patent US 10260000B2 (Evolve Etch by MacDermid Enthone) at 68° C. for 10 minutes
    • 3. Immersion in a 30% solution of 35% w/w hydrochloric acid at ambient temperature for 30 seconds
    • 4. Immersion in a proprietary palladium colloid solution (Evolve Activator by MacDermid Enthone) at ambient temperature for 3 minutes.
    • 5. Immersion in a proprietary accelerating solution (Evolve Accelerator 800 by MacDermid Enthone) at 50° C. for 2 minutes
    • 6. Immersion in an electroless nickel solution (Evolve EN-60 by MacDermid Enthone) at ambient temperature for 7 minutes Following this treatment, the entire plating rack was covered in a coating of nickel.

Example 2 (Comparative Example)

A plating rack with a coating of PVC plastisol was treated using the following sequence (rinse stages omitted for brevity):

    • 1. Immersion in a solution containing 10 g/l of thiourea at 70° C. for 10 minutes
    • 2. Immersion in an aqueous solvent blend containing 100 ml/l of propylene carbonate and 50 ml/l of butyrolactone at 35° C. for 3 minutes
    • 3. Etching in a chromium-free etchant based on the teachings on patent US 10260000B2 (Evolve Etch by MacDermid Enthone) at 68° C. for 10 minutes
    • 4. Immersion in a 30% solution of 35% w/w hydrochloric acid at ambient temperature for 30 seconds
    • 5. Immersion in a proprietary palladium colloid solution (Evolve Activator by MacDermid Enthone) at ambient temperature for 3 minutes.
    • 6. Immersion in a proprietary accelerating solution (Evolve Accelerator 800 by MacDermid Enthone) at 50° C. for 2 minutes
    • 7. Immersion in an electroless nickel solution (Evolve EN-60 by MacDermid Enthone) at ambient temperature for 7 minutes
    • 8. Plating in an acid copper electrolyte at ambient temperature for 40 minutes at a current density of 2 Adm−2

It was observed that after stage 6, no nickel coating was observed on the rack, but following stage 7, there was a significant amount of copper plating on the PVC plastisol coating.

Example 3

A plating rack with a coating of PVC plastisol was treated using the following sequence (rinse stages omitted for brevity):

    • 1. Immersion in a solution containing 0.05M of iodine at ambient temperature for 5 minutes
    • 2. Immersion in an aqueous solvent blend containing 100 ml/l of propylene carbonate and 50 ml/l of butyrolactone at 35° C. for 3 minutes
    • 3. Etching in a chromium-free etchant based on the teachings on patent US 10260000B2 (Evolve Etch by MacDermid Enthone) at 68° C. for 10 minutes
    • 4. Immersion in a 30% solution of 35% w/w hydrochloric acid at ambient temperature for 30 seconds
    • 5. Immersion in a proprietary palladium colloid solution (Evolve Activator by MacDermid Enthone) at ambient temperature for 3 minutes.
    • 6. Immersion in a proprietary accelerating solution (Evolve Accelerator 800 by MacDermid Enthone) at 50° C. for 2 minutes
    • 7. Immersion in an electroless nickel solution (Evolve EN-60 by MacDermid Enthone) at ambient temperature for 7 minutes
    • 8. Plating in an acid copper electrolyte at ambient temperature for 40 minutes at a current density of 2 Adm−2

Following this sequence, no nickel coating or copper plating was observed after treatment. This sequence was repeated for a further 4 cycles that omitted step 1. No plating on the PVC plastisol was observed over these cycles. It was confirmed that in the etching bath or any of the treatment steps, iodine did not undergo a change to form iodate ions.

Example 4

A plating rack with a coating of PVC plastisol was treated using the following sequence (rinse stages omitted for brevity):

    • 1. Immersion in a solution containing 0.01 M of iodine at ambient temperature for 5 minutes
    • 2. Immersion in an aqueous solvent blend containing 100 ml/l of propylene carbonate and 50 ml/l of butyrolactone at 35° C. for 3 minutes
    • 3. Etching in a chromium-free etchant based on the teachings on patent US 10260000B2 (Evolve Etch by MacDermid Enthone) at 68° C. for 10 minutes
    • 4. Immersion in a 30% solution of 35% w/w hydrochloric acid at ambient temperature for 30 seconds
    • 5. Immersion in a proprietary palladium colloid solution (Evolve Activator by MacDermid Enthone) at ambient temperature for 3 minutes.
    • 6. Immersion in a proprietary accelerating solution (Evolve Accelerator 800 by MacDermid Enthone) at 50° C. for 2 minutes
    • 7. Immersion in an electroless nickel solution (Evolve EN-60 by MacDermid Enthone) at ambient temperature for 7 minutes
    • 8. Plating in an acid copper electrolyte at ambient temperature for 40 minutes at a current density of 2 Adm−2

Following this sequence, no nickel coating or copper plating was observed after treatment. This sequence was repeated for a further 2 cycles that omitted step 1. No plating on the PVC plastisol was observed over these cycles. It was confirmed that in the etching bath or any of the treatment steps, iodine did not undergo a change to form iodate ions.

Example 5 (Comparative Example)

Two plating racks with coatings of different PVC plastisol were immersed in a solution of potassium iodate (30 g/l) at 70° C. for 20 minutes. No colour change was observed in the PVC plastisol of either plating rack. This is consistent with the colourless nature of potassium iodate solutions.

The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. A support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising iodine-treated and/or bromine-treated plastic.

2. The support of claim 1, wherein the contact surface comprises iodine-treated plastic.

3. The support of claim 1, wherein the plastic comprises PVC, preferably PVC plastisol.

4. The support of claim 1, wherein the support comprises metal at least partially coated with the plastic.

5. A plating apparatus for use in a chromic acid-free plating process, the plating apparatus comprising a plating vessel having one or more supports for supporting a component to be plated, the one or more supports having a contact surface comprising iodine-treated and/or bromine-treated plastic.

6. A method of treating a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic, the method comprising:

providing a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic;
providing an aqueous solution comprising one or both of iodine and bromine; and
contacting at least a portion of the plastic of the contact surface of the support with the aqueous solution.

7. The method of claim 6, wherein the aqueous solution comprises iodine.

8. The method of claim 7, wherein the aqueous solution comprises 0.005 to 0.1M iodine, preferably from 0.01 to 0.05 M iodine.

9. The method of claim 7, wherein the aqueous solution comprises iodide ions.

10. The method of claim 8, wherein the molar ratio of iodide ions to iodine is at least 1:1.

11. The method of claim 7, wherein the step of providing the aqueous solution comprises contacting iodide ions with an oxidizing agent in aqueous solution, the oxidising agent selected from iodate ions, persulfate ions, nitrate ions, hydrogen peroxide and combination of two or more thereof, preferably wherein the oxidizing agent comprises iodate ions.

12. The method of claim 6, wherein the support is contacted with the aqueous solution for at least 10 seconds, preferably at least 30 seconds, more preferably from 1 to 10 minutes, even more preferably from 1 to 5 minutes.

13. The method of claim 6, wherein the plastic of the contact surface of the support comprises PVC, preferably PVC plastisol.

14. The method of claim 6, wherein the plating process comprises plating on ABS polymer and/or ABS/PC polymer.

15. A method of manufacturing the support of claim 1, the method comprising the method of:

providing a support for supporting a component to be plated in a chromic acid-free plating process, the support having a contact surface comprising plastic;
providing an aqueous solution comprising one or both of iodine and bromine; and
contacting at least a portion of the plastic of the contact surface of the support with the aqueous solution.

16. A process for plating a component, the process comprising:

providing a component to be plated, the component having an outer surface comprising a plastic;
providing a plating apparatus comprising a plating vessel having one or more supports for supporting a component to be plated, the one or more supports having a contact surface comprising iodine-treated and/or bromine-treated plastic;
mounting the component on a support of the plating apparatus to provide a mounted component;
contacting at least a portion of the plastic of the outer surface of the mounted component with an electrolyte to at least partially etch the plastic to form an etched surface of the component, the electrolyte being substantially free of chromic acid; contacting at least a portion of the etched surface of the component with an activator solution to form an activated surface of the component; and
contacting at least a portion of the activated surface of the component with an electroless nickel solution or an electroless copper solution to form a plated surface of the component.

17. The process of claim 16, wherein:

the iodine-treated and/or bromine-treated plastic comprises PVC, preferably PVC plastisol; and/or the plastic of the outer surface of the component comprises ABS and/or ABS/PC.

18. The process of claim 16, wherein:

the electrolyte comprises manganese (III) ions in a solution of from 9 to 15 molar sulphuric or phosphoric acid; and/or
the activator solution comprises a precious metal colloid, preferably wherein the precious metal colloid comprises a first core metal and a colloid metal that colloidally surrounds the core; the core metal comprises at least one metal selected from the group consisting of silver, platinum, palladium and nickel; and the colloid metal comprises at least one metal selected from the group consisting of tin and lead.

19. The process of claim 16, wherein the process further comprises electroplating the plated surface of the component, and wherein the support comprises metal at least partially coated with the iodine-treated and/or bromine-treated plastic.

20. A method of using an iodine and/or bromine pre-treatment on a support for supporting a component to be plated to inhibit plating thereon during a chromic acid-free plating process, wherein the support has a contact surface comprising plastic, the method comprising the steps of:

contacting the contact surface comprising plastic with a solution of iodine and/or bromine to infuse iodine or bromine into a surface of the plastic.
Patent History
Publication number: 20230313382
Type: Application
Filed: Oct 2, 2020
Publication Date: Oct 5, 2023
Inventors: Trevor PEARSON (Waterbury, CT), Alison HYSLOP (Waterbury, CT), Amrik SINGH (Waterbury, CT), Roderick HERDMAN (Waterbury, CT)
Application Number: 17/754,502
Classifications
International Classification: C23C 18/16 (20060101); C23C 18/18 (20060101); C23C 18/32 (20060101); C23C 18/38 (20060101);