A method for selective metallization of a silicone rubber surface

Abstract

The application discloses a method for selectively metallizing a surface of silicone rubber. The method is characterized in that a polyethylene glycol derivative is mixed into a silicone rubber base, a hydrophilic group is selectively induced by laser, and a copper pattern is deposited through silver ion activation and a redox reaction of chemical plating, so that copper plating on the surface of the silicone rubber is effectively realized, the combination of the silicone rubber and the copper plating layer is ensured, and the surface of the silicone rubber is rapidly and selectively metallized. The application provides a method for the patterning requirement of flexible electronics, simplifies a process flow of chemical plating of the silicone rubber, reduces cost, and reduces environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics, and more particularly to a method for selective metallization of silicone rubber surfaces. Background Technology

[0002] With the development of flexible electronics technology and its cross-disciplinary integration, flexible electronics is advancing rapidly, moving towards intelligence, miniaturization, multi-parameter capabilities, and wireless functionality, resulting in increasingly diverse types and powerful functions. In particular, flexible matrix materials, with their advantages of flexibility, bendability, stretchability, and wearability, are gradually taking center stage. Flexible sensors, combining the advantages of flexible matrix materials with human-body adaptability, provide highly adaptable flexible devices for both wearable and implantable devices. Furthermore, the integration of flexible electronics technology has led to a series of applications such as flexible antennas.

[0003] Chemical copper plating is now widely used and can be applied to substrates such as metals, inorganic non-metallic materials, polymers, and composites. Currently, the main methods for metallizing silicone rubber surfaces include surface coating, plasma treatment, electrochemical treatment, and encapsulation. However, there are few methods in current research that directly modify the silicone rubber bulk to achieve selective metallization on its surface. In addition, existing bulk modification methods mostly involve adding oxide particles, which can affect the tensile properties of the material itself. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for selective metallization of silicone rubber surfaces. This invention employs mixing, induction, activation, and reduction steps to bulk modify silicone rubber, effectively achieving copper plating on the silicone rubber surface. This ensures the bonding between the silicone rubber and the copper plating layer, enabling rapid selective metallization of the silicone rubber surface. This provides a method for the patterning requirements of flexible electronics. Furthermore, the prepared flexible silicone rubber samples exhibit stretch resilience and conductivity. In addition, this invention simplifies the chemical plating process for silicone rubber, reduces costs, and minimizes environmental pollution.

[0005] The technical solution of the present invention is as follows:

[0006] This invention provides a method for selective metallization on the surface of silicone rubber, the method comprising the following steps:

[0007] (1) Preparation of precursor silicone rubber;

[0008] (2) Pour the precursor silicone rubber from step (1) into a mold, and perform vacuum degassing and curing to obtain cured precursor silicone rubber;

[0009] (3) Design the circuit pattern to be printed in advance in the laser control software, and then perform laser scanning on the precursor silicone rubber cured in step (2) according to the preset circuit pattern.

[0010] (4) The precursor silicone rubber after laser treatment in step (3) is placed in an activation solution for surface activation, and then dried to obtain activated silicone rubber.

[0011] (5) The activated silicone rubber was placed in a chemical copper plating solution for copper plating to obtain a copper-plated sample;

[0012] (6) Rinse the copper-plated sample from step (5) with deionized water or ultrasonically clean and dry it to obtain a flexible silicone rubber sample with copper metal lines.

[0013] Further, in step (1), the method for preparing the precursor silicone rubber is as follows: mixing silicone rubber, polyethylene glycol derivative and colorant, centrifuging to obtain precursor silicone rubber;

[0014] Further, the silicone rubber, polyethylene glycol derivative, and colorant, by mass parts, are 8-15 parts silicone rubber, 1-1.5 parts polyethylene glycol derivative, and 0.1-1 parts colorant, respectively; the polyethylene glycol derivative is one of polyethylene glycol methyl ether methacrylate (PEGMEM), poly(ethylene glycol) methyl ether acrylate (PEGMEA), poly(ethylene glycol) acrylate (PEGA), and poly(ethylene glycol) dimethacrylate (PEGDMA); the colorant is a silicone rubber colorant; the centrifugation speed is 4000-6000 rpm, and the time is 3-8 min.

[0015] Furthermore, in step (2), the vacuum degree of the vacuum degassing is -80 to -100 kPa, and the time is 1 to 2 hours.

[0016] Furthermore, in step (2), the curing time is 1.5 to 2 hours and the temperature is 150 to 180°C.

[0017] Further, in step (3), the laser scanning conditions are: laser line spacing of 25-75 μm, scanning speed of 500-4000 mm / s, laser frequency of 40-70 kHz, and laser power of 2-20 W.

[0018] Preferably, the laser line spacing is 50 μm, the scanning speed is 1000–3000 mm / s, the laser frequency is 40–60 kHz, and the laser power is 6–18 W.

[0019] Further, in step (4), the activation solution is a silver nitrate solution with a concentration of 8-10 g / L and a pH of 5-6; the surface activation temperature is 15-40°C and the time is 10-60 min.

[0020] Preferably, the pH value of the activation solution is 6;

[0021] Preferably, the surface activation temperature is 25–40°C and the time is 20–40 min.

[0022] Furthermore, in step (4), the drying temperature is 30-40°C and the drying time is 5-10 min.

[0023] Further, in step (5), the chemical copper plating solution is formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide, and formaldehyde in deionized water, with solute concentrations of 10-15 g / L for copper sulfate pentahydrate, 15-25 g / L for disodium ethylenediaminetetraacetate, 15-25 g / L for potassium sodium tartrate, 10-20 g / L for sodium hydroxide, and 15-20 ml / L for formaldehyde; the copper plating time is 1-2 hours, and the temperature is 25-40°C.

[0024] Furthermore, in step (6), the ultrasonic cleaning power is 120-150W, the frequency is 40-50kHz, and the time is 2-5min.

[0025] The beneficial technical effects of this invention are as follows:

[0026] The method for selective metallization of silicone rubber surface provided by the present invention can effectively achieve copper plating on silicone rubber surface by using mixing, induction, activation and reduction steps, ensuring the bonding between silicone rubber and copper plating layer, and realizing rapid selective metallization of silicone rubber surface.

[0027] This invention is the first to incorporate polyethylene glycol (PEG) derivatives into a silicone rubber substrate for laser-selective induced metallization. The appropriate amount of PEG derivatives provided the necessary conditions for laser induction. This invention modifies the silicone rubber matrix through the mixing of PEG derivatives, nearly doubling its tensile strength. Furthermore, laser treatment of the PEG derivative / silicone rubber cured sample generates hydrophilic groups. Since the PEG derivative material contains ether bonds, these bonds break under laser induction, forming carbon-oxygen double bonds and hydrophilic carboxyl groups. This allows silver ions to adsorb onto the treated silicone rubber surface, ultimately enabling the redox reaction of electroless plating to deposit copper patterns. This invention provides a method for patterning flexible electronics, simplifying the process of electroless plating of silicone rubber, reducing costs, and minimizing environmental pollution. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of selective metallization of silicone rubber surface according to the present invention.

[0029] Figure 2 This is a schematic diagram illustrating the principle of selective metallization of silicone rubber surface according to the present invention.

[0030] Figure 3 The image shows a comparison of the tensile properties of the precursor silicone rubber prepared in Examples 1 and 2 of this invention.

[0031] Figure 4 This is a classification diagram of the adhesion test results.

[0032] Figure 5 The images show the adhesion test results of the flexible silicone rubber sample prepared in Example 1 of this invention and the silicone rubber samples prepared in Comparative Examples 3 and 4.

[0033] Figure 6 The Fourier transform infrared spectra of the flexible silicone rubber sample prepared in Example 1 of this invention and the silicone rubber samples prepared in Comparative Examples 3 and 4 are shown.

[0034] Figure 7 The tensile strain resistance diagram is shown for the flexible silicone rubber sample prepared in Example 1 of this invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] This invention discloses a method for selective metallization on the surface of silicone rubber. The principle of selective metallization on the surface of silicone rubber is as follows: Figure 2 As shown, silicone rubber is modified by mixing polyethylene glycol derivatives. Because the polyethylene glycol derivatives contain ether bonds, these bonds break under laser induction, generating carbon-oxygen double bonds and forming hydrophilic carboxyl groups. This allows silver ions to be adsorbed onto the treated silicone rubber surface. Finally, copper ions are reduced on these active silver ions, undergoing a redox reaction to deposit a copper pattern. The specific reaction formula for the redox reaction is as follows:

[0037]

[0038] Example 1

[0039] A method for selective metallization on the surface of silicone rubber, the process flow of which is as follows: Figure 1 As shown, the specific steps include the following:

[0040] (1) Mix 11 parts silicone rubber, 1.22 parts PEGMEM and 0.5 parts colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0041] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0042] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0043] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0044] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0045] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes to obtain a flexible silicone rubber sample with copper metal circuitry.

[0046] Example 2

[0047] A method for selective metallization on the surface of silicone rubber, the process flow of which is as follows: Figure 1 As shown, the specific steps include the following:

[0048] (1) Mix 8 parts of silicone rubber, 1 part of PEGMEM and 0.1 parts of colorant by mass, and centrifuge at 4000 rpm for 8 min to obtain precursor silicone rubber.

[0049] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -80kPa for 2 hours, and then place it in an oven at 150℃ for 2 hours to cure it, thus obtaining the cured precursor silicone rubber.

[0050] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set as follows: power 6W, scanning speed 3000mm / s, frequency 60kHz, and laser line spacing 25μm.

[0051] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8 g / L and pH 5, and surface activated at 25°C for 40 minutes. Then it is dried in an oven at 30°C for 10 minutes to obtain activated silicone rubber.

[0052] (5) The activated silicone rubber was placed in a chemical copper plating solution at 40°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide, and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L, and formaldehyde 17 ml / L. (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 150 W and 50 kHz for 2 minutes to obtain a flexible silicone rubber sample with copper metal lines.

[0053] Example 3

[0054] A method for selective metallization on the surface of silicone rubber, the process flow of which is as follows: Figure 1 As shown, the specific steps include the following:

[0055] (1) Mix 15 parts silicone rubber, 1.5 parts PEGMEM and 1 part colorant by mass, and centrifuge at 6000 rpm for 3 min to obtain precursor silicone rubber.

[0056] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 160℃ for 2h to obtain the cured precursor silicone rubber.

[0057] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 40kHz, and laser line spacing 75μm.

[0058] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 10 g / L and pH 6, and surface activated at 40°C for 20 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0059] (5) The activated silicone rubber was placed in a chemical copper plating solution at 25°C for 2 hours to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12g / L, disodium ethylenediaminetetraacetate 21g / L, potassium sodium tartrate 16g / L, sodium hydroxide 15g / L and formaldehyde 17ml / L.

[0060] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 120W and 40kHz for 5 minutes to obtain a flexible silicone rubber sample with copper metal circuitry.

[0061] Example 4

[0062] A method for selective metallization on the surface of silicone rubber, the process flow of which is as follows: Figure 1 As shown, the specific steps include the following:

[0063] (1) Mix 11 parts silicone rubber, 1.22 parts PEGMEA and 0.5 parts colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0064] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0065] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 2000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0066] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 15°C for 60 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0067] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0068] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes to obtain a flexible silicone rubber sample with copper metal circuitry.

[0069] Example 5

[0070] A method for selective metallization on the surface of silicone rubber, the process flow of which is as follows: Figure 1 As shown, the specific steps include the following:

[0071] (1) Mix 11 parts silicone rubber, 1.22 parts PEGA and 0.5 parts colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0072] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0073] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set as follows: power 2W, scanning speed 500mm / s, frequency 40kHz, and laser line spacing 50μm.

[0074] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0075] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0076] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes to obtain a flexible silicone rubber sample with copper metal circuitry.

[0077] Example 6

[0078] A method for selective metallization on the surface of silicone rubber, the process flow of which is as follows: Figure 1 As shown, the specific steps include the following:

[0079] (1) Mix 11 parts silicone rubber, 1.22 parts PEGDMA and 0.5 parts colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0080] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0081] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 20W, scanning speed 3000mm / s, frequency 70kHz, and laser line spacing 50μm.

[0082] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0083] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0084] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes to obtain a flexible silicone rubber sample with copper metal circuitry.

[0085] Comparative Example 1

[0086] Under the experimental conditions of Example 1, no PEGMEM and colorant were added to the components, while the rest remained unchanged. As Comparative Example 1, the details are as follows:

[0087] (1) Take the same mass of silicone rubber as in Example (1) and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0088] (2) Pour the silicone rubber into the mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0089] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0090] Result: Cured precursor silicone rubber without the addition of PEGMEM and colorant could not absorb laser energy.

[0091] Comparative Example 2

[0092] Under the experimental conditions of Example 1, PEGMEM was not added to the components, and the rest remained unchanged, as Comparative Example 2, as follows:

[0093] (1) Mix 11 parts of silicone rubber and 0.5 parts of colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0094] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0095] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0096] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes, and then dried in an oven at 40°C for 5 minutes.

[0097] Results: Cured precursor silicone rubber without PEGMEM was unable to generate hydrophilic groups after laser scanning, which prevented silver nitrate from activating the laser-treated precursor silicone rubber.

[0098] Comparative Example 3

[0099] Under the experimental conditions of Example 1, the amount of PEGMEM in the composition was changed to 0.11 parts, while the rest remained unchanged. As Comparative Example 3, the details are as follows:

[0100] (1) By mass, 11 parts of silicone rubber, 0.11 parts of PEGMEM, and 0.5 parts of colorant were mixed and centrifuged at 5000 rpm for 5 min to obtain the precursor silicone rubber.

[0101] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0102] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0103] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0104] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0105] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes. It was impossible to obtain a flexible silicone rubber sample with copper metal circuits. Only a small amount of copper was found on the surface.

[0106] Comparative Example 4

[0107] Under the experimental conditions of Example 1, the amount of PEGMEM in the composition was changed to 0.58 parts, while the rest remained unchanged. As Comparative Example 3, the details are as follows:

[0108] (1) By mass, 11 parts of silicone rubber, 0.11 parts of PEGMEM, and 0.5 parts of colorant were mixed and centrifuged at 5000 rpm for 5 min to obtain the precursor silicone rubber.

[0109] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0110] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0111] (4) The precursor silicone rubber after laser treatment in step (3) is placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes. Then it is dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0112] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0113] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes to obtain a silicone rubber sample.

[0114] Comparative Example 5

[0115] Under the experimental conditions of Example 1, the laser scanning speed was changed to 100 mm / s, while all other parameters remained unchanged. This serves as Comparative Example 3, as detailed below:

[0116] A method for selective metallization on the surface of silicone rubber includes the following steps:

[0117] (1) Mix 11 parts silicone rubber, 1.22 parts PEGMEM and 0.5 parts colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0118] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0119] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 1000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0120] Result: The silicone rubber was severely burned due to the excessively slow scanning speed.

[0121] Comparative Example 6

[0122] Under the experimental conditions of Example 1, the laser scanning speed was changed to 4000 mm / s, while other parameters remained unchanged. As Comparative Example 3, the details are as follows:

[0123] (1) Mix 11 parts silicone rubber, 1.22 parts PEGMEM and 0.5 parts colorant by mass, and centrifuge at 5000 rpm for 5 min to obtain precursor silicone rubber.

[0124] (2) Pour the precursor silicone rubber into a mold, degas it under vacuum at -100kPa for 1h, and then place it in an oven at 180℃ for 1.5h to obtain the cured precursor silicone rubber.

[0125] (3) According to the preset circuit pattern, the precursor silicone rubber cured in step (2) is placed in water and the pattern is scanned by a Q-switched fiber laser. The laser parameters are set to power 18W, scanning speed 4000mm / s, frequency 50kHz, and laser line spacing 50μm.

[0126] (4) The precursor silicone rubber after laser treatment in step (3) was placed in silver nitrate at 8.5 g / L and pH 6, and surface activated at 30°C for 20 minutes. Then it was dried in an oven at 40°C for 5 minutes to obtain activated silicone rubber.

[0127] (5) The activated silicone rubber was placed in a chemical copper plating solution at 30°C for 1 hour to obtain a copper-plated sample. The chemical copper plating solution was formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide and formaldehyde in deionized water. The solute concentrations were: copper sulfate pentahydrate 12 g / L, disodium ethylenediaminetetraacetate 21 g / L, potassium sodium tartrate 16 g / L, sodium hydroxide 15 g / L and formaldehyde 17 ml / L.

[0128] (6) The copper-plated sample from step (5) was cleaned under ultrasonic conditions of 140W and 40kHz for 2 minutes, but a flexible silicone rubber sample with copper metal circuitry could not be obtained.

[0129] Test case

[0130] (1) Adhesion properties:

[0131] The flexible silicone rubber samples prepared in Example 1 and those prepared in Comparative Examples 3 and 4 were used for adhesion performance testing. According to the ASTM D3359 grading standard, a higher grade indicates stronger adhesion between the polymer substrate and the coating. Specifically: 0B mesh showed a peeling area greater than 65%; 1B mesh showed a peeling area of ​​35%-65%; 2B mesh showed a peeling area of ​​15%-35%; 3B mesh showed a peeling area of ​​5%-15%; 4B mesh showed a peeling area of ​​5%; and 5B showed no mesh peeling. A schematic diagram of the grading results is shown below. Figure 4 The result is as follows Figure 5 As shown. By observing and comparing Figure 5 and Figure 4 It can be seen that the adhesion grade of the flexible silicone rubber sample with copper metal circuit prepared in Example 1 can reach 4B. However, the surface area of ​​the silicone rubber samples prepared in Comparative Examples 3 and 4 can be plated with copper, but the copper plating layer is very easy to peel off from the silicone rubber surface, the plating effect is poor, and the adhesion grade is 0B.

[0132] (2) Hydrophilic group content:

[0133] The flexible silicone rubber samples prepared in Example 1 and those prepared in Comparative Examples 3 and 4 were analyzed using Fourier transform infrared spectroscopy to determine the content of hydrophilic groups. The results are as follows: Figure 6 As shown. Observation Figure 6 It can be seen that the addition of PEGMEM can generate hydrophilic groups, according to the Fourier transform infrared spectroscopy wavenumber at 1730 cm⁻¹. -1The fluctuations indicate the formation of carbon-oxygen double bonds, meaning the presence of hydrophilic carboxyl groups. Based on the fluctuations observed in materials with different PEGMEM contents, it can be concluded that higher PEGMEM content results in the formation of more hydrophilic groups.

[0134] (3) Tensile properties:

[0135] The flexible silicone rubber sample with copper metal lines prepared in Example 1 was used to test the resistance of the metal pattern under tension using a universal testing machine. If the resistance increases under tension but the continuity is still maintained, it indicates that the tensile performance is "good". The results are as follows: Figure 7 As shown. Observation Figure 7 It can be seen that after copper plating, the tensile strength and resistance change. When the tensile strain reaches 40%, the resistance is below 40 ohms, and the resistance increases steadily along a certain trend. The precursor silicone rubbers obtained in Example 1 and Comparative Examples 1-2 were used to test the tensile properties of different materials using a universal testing machine. The results are as follows... Figure 3 As shown in the diagram, the tensile properties reveal that the added PEGMEM material not only induces selective metallization on the silicone rubber surface but also nearly doubles the tensile strength of the silicone rubber itself.

[0136] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for selective metallization on the surface of silicone rubber, characterized in that, The method includes the following steps: (1) Preparation of precursor silicone rubber; (2) Pour the precursor silicone rubber from step (1) into a mold, and perform vacuum degassing and curing to obtain cured precursor silicone rubber; (3) The precursor silicone rubber cured in step (2) is laser scanned according to the preset circuit pattern; (4) The precursor silicone rubber after laser treatment in step (3) is placed in an activation solution for surface activation, and then dried to obtain activated silicone rubber. (5) The activated silicone rubber was placed in a chemical copper plating solution for copper plating to obtain a copper-plated sample; (6) The copper-plated sample from step (5) is ultrasonically cleaned and air-dried at room temperature to obtain a flexible silicone rubber sample with copper metal lines. In step (1), the precursor silicone rubber is prepared by mixing silicone rubber, polyethylene glycol derivative and colorant, centrifuging to obtain precursor silicone rubber; The polyethylene glycol derivatives include one or more of polyethylene glycol methyl ether methacrylate, poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) acrylate, and poly(ethylene glycol) dimethacrylate; In step (4), the activation solution is a silver nitrate solution.

2. The method according to claim 1, characterized in that, The precursor silicone rubber comprises the following components in parts: 8-15 parts silicone rubber, 1-1.5 parts polyethylene glycol derivative, and 0.1-1 parts colorant; the colorant is a silicone rubber colorant; the centrifugation speed is 4000-6000 rpm, and the time is 3-8 min.

3. The method according to claim 1, characterized in that, In step (2), the vacuum degree of the vacuum degassing is -80 to -100 kPa, and the time is 1 to 2 hours.

4. The method according to claim 1, characterized in that, In step (2), the curing time is 1.5 to 2 hours and the temperature is 150 to 180°C.

5. The method according to claim 1, characterized in that, In step (3), the laser scanning conditions are: laser line spacing of 25-75 μm, scanning speed of 500-3000 mm / s, laser frequency of 40-70 kHz, and laser power of 2-20 W.

6. The method according to claim 5, characterized in that, The laser line spacing is 50μm, the scanning speed is 1000~3000mm / s, the laser frequency is 40~60kHz, and the laser power is 6~18W.

7. The method according to claim 1, characterized in that, In step (4), the activation solution is a silver nitrate solution with a concentration of 8-10 g / L and a pH of 5-6; the surface activation temperature is 15-40°C and the time is 10-60 min.

8. The method according to claim 7, characterized in that, The pH value of the activation solution is 6; the surface activation temperature is 25-40℃ and the time is 20-40 min.

9. The method according to claim 1, characterized in that, In step (4), the drying temperature is 30-40°C and the time is 5-10 minutes.

10. The method according to claim 1, characterized in that, In step (5), the chemical copper plating solution is formulated by dissolving anhydrous copper sulfate, disodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium hydroxide, and formaldehyde in deionized water, with solute concentrations of 10-15 g / L for copper sulfate pentahydrate, 15-25 g / L for disodium ethylenediaminetetraacetate, 15-25 g / L for potassium sodium tartrate, 10-20 g / L for sodium hydroxide, and 15-20 ml / L for formaldehyde; the copper plating time is 1-2 hours, and the temperature is 25-40°C.

11. The method according to claim 1, characterized in that, In step (6), the ultrasonic cleaning power is 120-150W, the frequency is 40-50kHz, and the time is 2-5min.

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