CN117888158A

CN117888158A - Plateable conductive polymer part and forming method

Info

Publication number: CN117888158A
Application number: CN202311318645.5A
Authority: CN
Inventors: 黛博拉·弗朗西斯·米耶斯基; 保罗·肯尼士·戴尔洛克; 拉隆·米歇尔·布朗; 斯图尔特·C·索尔特; 阿尔珀·克孜尔塔斯
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2022-10-14
Filing date: 2023-10-12
Publication date: 2024-04-16
Also published as: DE102023127966A1; US20240125000A1

Abstract

The present disclosure provides "plateable conductive polymer parts and forming methods". A method of plating a substrate includes etching at least a portion of a surface of the substrate to form a void within the surface. The substrate includes a composite material having a network of conductive nanostructures dispersed therein. An electrode is attached to the substrate, the substrate is placed in a plating solution of a first conductive metal, and a voltage is applied to the substrate through the electrode to deposit a first conductive metal layer onto the surface of the substrate and a second conductive metal layer is plated thereon.

Description

Plateable conductive polymer part and forming method

Technical Field

The present disclosure relates to electroplated polymer parts, and more particularly to electroplated polymer parts for automotive applications having specific polishing requirements.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

Plastic parts are often plated with chrome or other similar materials to provide improved aesthetics for exterior components of the motor vehicle, such as, for example, a front grill or other decorative component. Conventional processes for coating polymer or plastic parts with chromium involve a multi-step process that makes the surface of the plastic part conductive.

Referring to fig. 1, a conventional process 100 for making plastic parts conductive includes first cleaning the surface of a substrate at 102. Cleaning the surface helps remove debris, dirt, smudges, fingerprints, etc. In general, a mild alkaline cleaner is sufficient, but in some applications thorough wetting with an acidic solution (e.g., chromic acid) may be desirable. After cleaning, the substrate is pre-immersed in a solvent prior to etching at 104. This may increase the rate at which the etchant reaches and attacks the substrate surface. After pre-dipping, the substrate is etched with an etchant at 106. Etching increases the surface area of the substrate and creates micro-pores that facilitate bonding with the deposited metal. Suitable etchants include chromic acid or sulfuric acid. At 108, a conditioner is optionally applied to the etched substrate. The modulator may promote more uniform absorption during the activation phase. After optional conditioning or etching (if not optional conditioning), the etched substrate is neutralized (e.g., rinsed) at 110 to remove excess acid/etchant. Suitable neutralizing agents include, but are not limited to, sodium bisulfite or other neutralizing agents provided for removal of the etchant. After neutralization, the etched substrate is activated at 112 to act as a catalyst during plating. Activation may be facilitated by the introduction of low concentrations of noble metal liquid activators (e.g., palladium, platinum, gold, etc.), and the activation serves to significantly reduce the strip-out cost. After activation, the accelerator removes excess stannous hydroxide at 114, which helps the activator act as a catalyst and inhibits the occurrence of skip plating. The etched substrate may then be rinsed and a metal coating (e.g., copper, nickel) is deposited on the etched substrate via an electroless plating solution at 116, which renders the etched substrate conductive. After the surface of the plastic part is made conductive, the process ends and further processing is used to coat the plastic part with a chromium layer.

The thickness of the chromium or metal coating on the plastic part according to conventional processes may vary throughout the plastic part depending on the part geometry. For example, automotive grilles plated according to conventional processes may produce thickness variations ranging from about 4 microns to 50 microns. Such variations may be caused by deep surfaces of the part to be coated (e.g., fog lamp edges). To counteract such dimensional changes, the geometry of the substrate itself may be tailored (e.g., to shorten the depth of cracks, pockets, depressions, etc. of the substrate) or the residence time of the substrate in the electroless plating solution may be increased. An auxiliary anode may also be employed to facilitate metal plating on the surface of a substrate having deeper cracks, pockets, depressions, etc. Unfortunately, when thickness tolerances are exceeded, further finishing is required to provide a uniform layer of metal coating on the substrate, resulting in increased cost and cycle time.

The present disclosure addresses these and other problems associated with coating plastic parts with aesthetic materials such as chromium or nickel.

Disclosure of Invention

This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

According to one form of the present disclosure, a method of plating a substrate includes etching at least a portion of a surface of the substrate to form voids within the surface. The substrate includes a composite material having a network of conductive nanostructures disposed within a thermoplastic matrix. An electrode is attached to the substrate and the substrate is placed into a plating solution of a first conductive metal. A voltage is applied to the substrate through the electrode and is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate. A second conductive metal is electroplated onto the first conductive metal layer to form a second conductive metal layer.

In variations of this form (which may be implemented alone or in any combination): the amount of the conductive nanostructures is about 0.5 wt% of the composite; the first conductive metal is copper and the second conductive metal is nickel; the first conductive metal comprises at least one of copper, copper alloy, nickel, and nickel alloy; the thermoplastic matrix comprises at least one of acrylonitrile-butadiene-styrene (ABS) and polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS); the conductive nanostructure network comprises carbon nanotubes; the first conductive metal layer has a thickness between about 20 μm and about 40 μm; conducting the voltage through the auxiliary anode disposed along a perimeter of the substrate; plating the substrate without using an electroless plating process; electroplating a third conductive metal onto the second conductive metal layer to form a third conductive metal layer; the second conductive metal is nickel and the third conductive metal is chromium; and plating the part according to the present method.

According to another form of the present disclosure, a method of plating a substrate includes etching at least a portion of a surface of the substrate to form voids within the surface. The substrate includes a composite material having a network of conductive nanostructures disposed within a thermoplastic matrix. The amount of the conductive nanostructured network is about 0.5 wt% of the composite material. An electrode is attached to the substrate and the substrate is placed into a plating solution of a first conductive metal. A voltage is applied to the substrate through the electrode and is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate and a second conductive metal is electroplated onto the first conductive metal layer to form a second conductive metal layer.

In variations of this form (which may be implemented alone or in any combination): the first conductive metal layer has a thickness between about 20 μm and about 40 μm; conducting the voltage through the auxiliary anode disposed along a perimeter of the substrate; and the first conductive metal is copper and the second conductive metal is nickel.

In yet another form of the present disclosure, a method of plating a substrate includes etching at least a portion of a surface of the substrate to form voids within the surface. The substrate includes a composite material having a network of conductive nanostructures disposed within a thermoplastic matrix, and the network of conductive nanostructures is present in an amount of about 0.5 wt% of the composite material. An electrode is attached to the substrate, and the substrate is placed into a plating bath that includes a first conductive metal that includes one of copper and a copper alloy. A voltage is applied to the substrate through the electrode and is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate at a thickness between about 20 μm and about 40 μm. A second conductive metal is electroplated onto the first conductive metal layer to form a second conductive metal layer.

In variations of this form (which may be implemented alone or in any combination): conducting the voltage through the auxiliary anode disposed along a perimeter of the substrate; plating the substrate without using an electroless plating process; a third conductive metal is electroplated onto the second conductive metal layer to form a third conductive metal layer.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

In order that the disclosure may be better understood, various forms of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a flowchart showing a conventional method for making a substrate conductive according to the prior art;

FIG. 2 is a schematic illustration of a composite material according to the present disclosure;

FIG. 3 is a schematic view of an apparatus for manufacturing a composite material according to FIG. 2; and

Fig. 4 is a flow chart illustrating a method for metal plating a substrate according to the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

Detailed Description

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

The present disclosure provides a method of plating a metal layer on a substrate (e.g., a plastic part) without the need for an intermediate electroless plating step (set forth above). In general, substrates having a surface resistivity of less than 1x10 ⁸ ohm-meters (Ω -m) are suitable for achieving an electrostatic surface to plate a metal layer (e.g., chromium) on the substrate surface. In one form, the substrate has a surface resistivity of less than 1x10 ⁴ ohm-meters (Ω -m).

Referring to fig. 2, a composite material in accordance with the present disclosure is shown and generally indicated by reference numeral 20. The substrate is made of a composite material 20, and the composite material 20 includes a thermoplastic matrix 22 and a network of conductive nanostructures 24 dispersed within the thermoplastic matrix 22. Optionally, the composite material 20 further includes a plurality of additives 26, which are described in more detail below.

As used herein, the phrase "conductive nanostructure network" should be interpreted to mean a crosslinked network of nanostructures connected at a plurality of nodes 28 that together form a conductive pathway throughout the composite 20. In one form, the nanostructure is a carbon nanostructure. The network of conductive nanostructures 24 further reduces the resistivity of the composite material 20, thereby increasing the efficiency of the plating process. Thus, the conductive network of linked nanostructures 24 provides sufficient conductivity to create a static dissipative composite 20 to achieve efficient plating, as described in more detail below. It should be appreciated that while the network of conductive nanostructures 24 is shown connected at node 28, not all networks of conductive nanostructures 24 need be connected while remaining within the scope of the present disclosure. The network of conductive nanostructures 24 is provided in an amount to provide the desired resistivity of the composite material 20 for the plating process.

In order to form a network of conductive nanostructures 24 that is sufficient for the desired conductivity, a large amount of shear is required to untangling the nanostructures as they are processed, which enables further conductivity improvements. More specifically, the amount of shear processing during compounding of the composite material 20 has a significant impact on the final material properties. Thus, the electrical conductivity and surface resistivity of the composite material 20 can be adjusted as desired depending on the amount of nanostructures introduced and the amount of shear used in processing the nanostructures.

Referring to fig. 3, there is shown one form of apparatus 30 for performing the methods described herein. In this form, apparatus 30 is a high speed twin extruder having co-rotating screws designed to have a high shear section and a low shear section. High shear typically untwists the carbon nanostructures, enabling further conductivity enhancement as described above. In one form, the extruder has a length to diameter ratio of at least about 32:1, and more specifically greater than about 40:1, to provide a more homogeneous mixture. The thermoplastic matrix 22 and nanostructures are added at or before the first feeder 32 and mixed under high shear in the first mixing section 34. Any additives (e.g., additive 36) are optionally added to the second feeder 38 after the high shear portion of the extruder and mixed at lower shear in the second mixing section 40. The composite material 20 may be fed from the apparatus 30 into an injection molding apparatus (not shown) or other forming process and formed into a desired part for a substrate.

The thermoplastic matrix 22 may be any of a variety of thermoplastic materials including, for example, acrylonitrile Butadiene Styrene (ABS) or polycarbonate/acrylonitrile butadiene styrene. In one form, the thermoplastic matrix 22 comprises a platable grade ABS (i.e., ABS having a higher concentration of butadiene than a standard grade), which enables efficient etching of the substrate surface, creating more voids and surface area for copper filling, as described in more detail below.

In one form of the present disclosure, the network of conductive nanostructures 24 is added in an amount of about 0.5 wt.% to achieve a surface resistivity of about 1x10 ³ ohm meters (Ω -m). It is contemplated that lower or higher amounts of conductive nanostructures 24 may be implemented depending on the desired resistivity. Substrates prepared according to the present disclosure exhibit improved electrical conductivity, which allows for elimination of electroless plating of the substrate required under conventional processing of metal plated substrates. In addition, the substrate plated according to the present disclosure exhibits a more uniform metal plating thickness than the substrate plated under conventional processes.

In one form of the present disclosure, at least a portion of the substrate surface is etched prior to electroplating. Etching forms voids in the substrate surface that help bond with the deposited metal.

Referring now to fig. 4, a method 200 for plating a substrate comprising a composite material 20 as set forth above includes etching at least a portion of a surface of the substrate at 202. As set forth above, etching forms voids within the substrate surface. The electrode is attached to the substrate at 204. At 206, the substrate is placed into a plating solution comprising a first conductive material. At 208, a voltage is applied to the substrate through the electrode such that the voltage is conducted through the conductive nanostructure network to deposit the first conductive metal layer onto the substrate surface. In one form the first conductive metal layer has a thickness between about 20 μm and about 40 μm. At 210, a second conductive metal is electroplated onto the first conductive metal to form a second conductive metal layer.

In one form, the first conductive metal is copper and the second conductive metal is nickel, but the present disclosure should be construed to include other metals that allow further processing/plating in accordance with the teachings of the present disclosure. Other metals include, by way of non-limiting example, copper alloys, nickel and nickel alloys, and the like. Optionally, a third conductive metal is electroplated onto the second conductive metal layer to form the third conductive metal layer. In this form, the third conductive metal layer is chromium.

In one form of the present disclosure, the voltage is conducted through auxiliary anodes disposed along the periphery of the substrate, which are not shown for clarity.

The plated parts disclosed herein may be used in a variety of applications where it is desirable to have a more uniform, simplified process to plate the parts with a metal layer without the need for an intermediate electroless plating step. For example, such parts may include, but are not limited to, grills and trim parts in the automotive and motor vehicle industries.

Unless expressly indicated otherwise herein, all numerical values indicating mechanical/thermal properties, percentages of composition, dimensions and/or tolerances or other characteristics are to be understood as modified by the word "about" or "approximately" in describing the scope of the present disclosure. Such modifications are desirable for a variety of reasons, including: industry practice; materials, manufacturing and assembly tolerances; capability testing.

As used herein, at least one of the phrases A, B and C should be construed to use a non-exclusive logical or to represent logic (a or B or C) and should not be construed to represent at least one of a, at least one of B, and at least one of C.

The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.

According to the present invention, a method of plating a substrate comprises: etching at least a portion of a surface of the substrate to form voids within the surface, the substrate comprising a composite material having a network of conductive nanostructures dispersed within a thermoplastic matrix; attaching an electrode to the substrate; placing the substrate into a plating solution comprising a first conductive metal; applying a voltage to the substrate through the electrode, wherein the voltage is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate; and electroplating a second conductive metal onto the first conductive metal layer to form a second conductive metal layer.

In one aspect of the invention, the amount of the conductive nanostructures is about 0.5 wt% of the composite.

In one aspect of the invention, the first conductive metal is copper and the second conductive metal is nickel.

In one aspect of the invention, the first conductive metal comprises at least one of copper, copper alloy, nickel, and nickel alloy.

In one aspect of the invention, the thermoplastic matrix comprises at least one of acrylonitrile-butadiene-styrene (ABS) and polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS).

In one aspect of the invention, the conductive nanostructure network comprises carbon nanostructures.

In one aspect of the invention, the first conductive metal layer has a thickness between about 20 μm and about 40 μm.

In one aspect of the invention, the method includes conducting the voltage through an auxiliary anode disposed along a perimeter of the substrate.

In one aspect of the invention, the substrate is not plated using an electroless plating process.

In one aspect of the invention, the method includes electroplating a third conductive metal onto the second conductive metal layer to form a third conductive metal layer.

In one aspect of the invention, the second conductive metal is nickel and the third conductive metal is chromium.

In one aspect of the invention, the part is plated according to the method of the previous embodiment.

According to the present invention, a method of plating a substrate comprises: etching at least a portion of a surface of the substrate to form voids within the surface, the substrate comprising a composite material having a network of conductive nanostructures dispersed within a thermoplastic matrix, the network of conductive nanostructures being present in an amount of about 0.5 wt% of the composite material; attaching an electrode to the substrate; placing the substrate into a plating solution comprising a first conductive metal; applying a voltage to the substrate through the electrode, wherein the voltage is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate; and electroplating a second conductive metal onto the first conductive metal layer to form a second conductive metal layer.

According to the present invention, a method of plating a substrate comprises: etching at least a portion of a surface of the substrate to form voids within the surface, the substrate comprising a composite material having a network of conductive nanostructures dispersed within a thermoplastic matrix, the network of conductive nanostructures being present in an amount of about 0.5wt% of the composite material; attaching an electrode to the substrate; placing the substrate into a plating bath comprising a first conductive metal comprising one of copper and a copper alloy; applying a voltage to the substrate through the electrode, wherein the voltage is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate at a thickness between about 20 μιη and about 40 μιη; and electroplating a second conductive metal onto the first conductive metal layer to form a second conductive metal layer.

Claims

1. A method of plating a substrate, the method comprising:

etching at least a portion of a surface of the substrate to form voids within the surface, the substrate comprising a composite material having a network of conductive nanostructures dispersed within a thermoplastic matrix;

attaching an electrode to the substrate;

Placing the substrate into a plating solution comprising a first conductive metal;

applying a voltage to the substrate through the electrode, wherein the voltage is conducted through the conductive nanostructure network to deposit a first conductive metal layer onto the surface of the substrate; and

A second conductive metal is electroplated onto the first conductive metal layer to form a second conductive metal layer.

2. The method of claim 1, wherein the amount of the conductive nanostructures is about 0.5 wt% of the composite.

3. The method of claim 1, wherein the first conductive metal is copper and the second conductive metal is nickel.

4. The method of claim 1, wherein the first conductive metal comprises at least one of copper, copper alloy, nickel, and nickel alloy.

5. The method of claim 1, wherein the thermoplastic matrix comprises at least one of acrylonitrile-butadiene-styrene (ABS) and polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS).

6. The method of claim 1, wherein the conductive nanostructure network comprises carbon nanostructures.

7. The method of claim 1, wherein the first conductive metal layer has a thickness between about 20 μιη and about 40 μιη.

8. The method of claim 1, further comprising conducting the voltage through an auxiliary anode disposed along a perimeter of the substrate.

9. The method of claim 1, wherein the substrate is not plated using an electroless plating process.

10. The method of claim 1, further comprising electroplating a third conductive metal onto the second conductive metal layer to form a third conductive metal layer.

11. The method of claim 10, wherein the second conductive metal is nickel and the third conductive metal is chromium.

12. The method of claim 11, wherein the amount of conductive nanostructures is about 0.5 wt% of the composite, and the thickness of the first conductive metal layer is between about 20 μιη and about 40 μιη.

13. The method of claim 10, wherein the amount of conductive nanostructures is about 0.5 wt% of the composite, and the thickness of the first conductive metal layer is between about 20 μιη and about 40 μιη.

14. The method of claim 1, wherein the amount of the conductive nanostructure is about 0.5 wt% of the composite material, and the thickness of the first conductive metal layer is between about 20 μιη and about 40 μιη.

15. A part plated according to the method of claim 1.