A stretchable metal-based electrical / thermal conductor

Abstract

The present application discloses a stretchable metal-based electrical / thermal conductor, which belongs to the field of printed electronics. S1, configures a multifunctional silicone gel; S2, configures an epoxy film with a wrinkled surface; S3, prints the multifunctional silicone gel prepared by S1 on a rubber film, covers it with the epoxy film prepared by S2 as a template, heats and cures it, and obtains a molded silicone gel pattern; then immerses the silicone gel pattern in a saturated silver nitrate ethanol solution to obtain a catalyst-loaded silicone gel pattern; then metallizes the pattern by chemical copper plating to obtain a stretchable copper conductive pattern. Therefore, the present application adopts the above-mentioned stretchable metal-based electrical / thermal conductor, and the copper pattern prepared by the present invention has a compact structure. Its electrical conductivity is 4.93×107Sm ‑1 , close to the theoretical value of pure copper block; good thermal conductivity, thermal conductivity is 320.2W / (mK); unidirectional stretch product strain can reach 190%, multi-directional stretch product strain can reach 110%.

Description

Technical Field

[0001] The present application belongs to the field of printed electronics, and specifically relates to a stretchable metal-based electrical / thermal conductor. Background Art

[0002] In the past few decades, wearable, epidermal and implantable electronics have developed rapidly, and people's interest in stretchable electronics has continued to grow. Stretchable electronic devices are far superior to traditional bendable devices in coordinated movement. At present, the application of stretchable electronic devices is very wide, and they are used in the fields of electronic skin, energy, medicine and electronic packaging. In electronic devices, printed circuits play a vital role in the electrical connection of components, which is the primary consideration for the manufacture of stretchable electronic devices. In general, stretchable conductive patterns can be fabricated by using intrinsically stretchable conductors or structurally stretchable wires with wavy geometries. Intrinsically stretchable conductors mainly include liquid metals, conductive polymers and composites. The patterning process involved in intrinsically stretchable circuits is usually not complicated, but its development is largely limited by its own defects. For example, liquid metals are expensive and corrosive to electronic products, and their fluidity also increases the difficulty of manufacturing and safe application. In terms of conductivity, conductive polymers and composites are far inferior to traditional metal interconnects, which is not conducive to their application in modern high-power density electronics.

[0003] In addition to intrinsic stretchable conductors, any bendable material can be converted into a stretchable material through reasonable geometric design, including traditional metal copper conductors in printed circuit boards. This stretching mode is called "structural stretching". Existing structural stretching strategies are mainly divided into two types: "in-plane" and "out-of-plane" strategies. Among them, the in-plane strategy is to prepare curved patterns on an elastic substrate by printing or etching technology. The out-of-plane strategy usually prepares a conductive layer on a pre-stretched elastic substrate, and an out-of-plane wrinkled structure can be generated after returning to normal. The two existing strategies each have their advantages and limitations. The "in-plane" strategy prepares highly conductive metal materials into twisted wires. Compared with traditional straight wires, the twisted pattern occupies a larger area and requires a high thickness-to-width ratio to maintain sufficient mechanical strength during stretching. The curved geometric pattern is not conducive to high-density packaging of electronic products and will lead to increased resistance. Compared with the "in-plane" strategy, the conductive pattern prepared by this method does not need to occupy a larger area than the traditional circuit. However, the corrugated conductive layer produced by the pre-stretching method must withstand strong shear and bending stresses under normal circumstances, so the coating is required to have strong mechanical strength and high adhesion strength. Although they are similar to commercial interconnect circuits in terms of electrical performance, the curved geometry of structurally stretched conductors makes their manufacturing process and practical application more complicated than traditional straight conductors. In view of this, the present invention aims to develop a structural stretching strategy that combines the advantages of both "in-plane" and "out-of-plane" strategies, in order to obtain multi-directionally stretched printed circuits on a flat elastic substrate without pre-stretching through a simple process. Summary of the invention

[0004] The purpose of the present application is to prepare a stretchable metal-based electrical / thermal conductor, by chemically plating on the surface of a printed and shaped silicone gel pattern to obtain a new type of structural stretch circuit, thereby realizing a new product that combines the advantages of traditional "in-plane" and "out-of-plane" stretching structures.

[0005] The present invention provides a stretchable metal-based electrical / thermal conductor, comprising the following preparation steps:

[0006] S1. Prepare multifunctional silicone gel.

[0007] S2. An epoxy film having a wrinkled surface is provided.

[0008] S3, printing the multifunctional silicone gel prepared in S1 on a rubber film by various patterning techniques, covering it with the epoxy film prepared in S2 as a template, heating and curing it, and obtaining a formed silicone gel pattern.

[0009] S4. Immerse the silica gel pattern prepared in S3 into a saturated silver nitrate ethanol solution to form a catalytic seed layer, thereby obtaining a silica gel pattern loaded with a catalyst.

[0010] S5. The catalyst-loaded silica gel pattern obtained in S4 is metallized by a chemical copper plating process to obtain a stretchable copper conductive pattern.

[0011] Preferably, the specific steps of step S1 are: mixing 5-20% Schiff base solution, 2-10% gas phase SiO2, 70-90% PDMS and a curing agent to obtain a multifunctional silicone gel.

[0012] Preferably, the specific steps of step S2 are: coating epoxy resin on the rubber film in a stretched state, releasing the strain after heating and curing, continuing to coat the epoxy resin in an unstretched state, and peeling off the rubber film after curing to obtain an epoxy film with wrinkles on the surface.

[0013] Preferably, in S1, in the Schiff base solution, the Schiff base is dissolved in the liquid epoxy resin to form a saturated solution; the Schiff base is o-vanillin ethylenediamine bis-Schiff base, or is replaced by other nitrogen-containing multidentate ligands; the ligands include: 1,1',1"-tris[(pyridine-4-oxy)methyl]ethane, 1-(1H-1,2,4-triazolylmethyl)-3,5-bipyridyl-1,2,4-triazole, tris(4-imidazolylphenyl)amine, (4-(1-H-1,2,4-triazolyl)phenyl)amine, 1,1'-(1,4-butyl)bis[2-(2-pyridyl)benzimidazole] or one or more thereof.

[0014] Preferably, in S1, the PDMS is one or more of dimethylmethoxysilane, dimethylsiloxane alcohol methyl chain end blocking agent, and dimethylsiloxane chloromethyl chain end blocking agent.

[0015] Preferably, in S1, the curing agent is one or more of hexamethyldisiloxane, tetrahydrosilanol, and trichloroethylsilanol.

[0016] Preferably, in S2, the curing heating temperature is 90-110° C., and the heating time is 60 minutes.

[0017] Preferably, in S3, the curing heating temperature is 140-160° C., and the heating time is 60 minutes; the rubber film is one or more of a natural rubber film, a polyurethane film, a chloroprene film, and a silicone rubber film.

[0018] Preferably, in S4, the immersion time in the silver nitrate ethanol solution is 25-35 minutes.

[0019] Preferably, in S5, the composition of the electroless copper plating process plating solution includes copper sulfate, EDTA, sodium hydroxide, potassium sodium tartrate, the pH is controlled at 12.5, and the temperature is controlled at 45°C.

[0020] Therefore, the present application adopts the above-mentioned stretchable metal-based electrical / thermal conductor, which has the following beneficial effects:

[0021] (1) The present invention is the first to construct a multi-directionally stretchable printed circuit on a normal (not pre-stretched) flat substrate by introducing a medium layer (a new type of multifunctional silicone gel), thereby realizing a new product that combines the advantages of traditional "in-plane" and "out-of-plane" stretching structures.

[0022] (2) The silver catalyst of the present invention can be reduced in situ on the surface of the gel pattern, and its catalytic sites are completely exposed, thereby achieving a catalytic activity far higher than that of traditional composite catalysts, thereby greatly reducing the use of precious metal catalysts.

[0023] (3) The multifunctional silicone gel of the present invention has plasticity, stretchability, printability and the ability to reduce silver catalyst, which plays a vital role in the preparation of stretchable copper patterns and can achieve stretching and printing functions at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of the process flow of a stretchable metal-based electrical / thermal conductor of the present invention; wherein the PSS adhesive is a multifunctional silicone gel, and the PDMS film is a type of silicone rubber film;

[0025] Figure 2 is a photograph of a copper conductive pattern prepared on a polyimide substrate in process example 1 of a stretchable metal-based electrical / thermal conductor of the present invention;

[0026] Figure 3 is a SEM image of the surface of the copper conductive pattern prepared in process example 1 of a stretchable metal-based electrical / thermal conductor of the present invention;

[0027] Figure 4 is an XRD spectrum of the surface of the copper conductive pattern prepared in process example 1 of a stretchable metal-based electrical / thermal conductor of the present invention;

[0028] Figure 5 The electrical conductivity of the copper plating layer, commercial conductive adhesive and copper foil prepared in the process embodiment 1 of the present invention is a stretchable metal-based electrical / thermal conductor;

[0029] Figure 6 is an infrared thermal imaging image of a copper plating layer, a commercial conductive adhesive and a copper foil prepared in process example 1 of a stretchable metal-based electrical / thermal conductor of the present invention;

[0030] Figure 7 It is a comparison diagram of the stretchable copper conductive pattern prepared in process example 1 of a stretchable metal-based electrical / thermal conductor of the present invention and the copper conductive pattern prepared in comparative example 1, as well as an infrared thermal imaging diagram of the conductor under an applied current. DETAILED DESCRIPTION

[0031] The present invention provides a stretchable metal-based electrical / thermal conductor, comprising the following preparation steps:

[0032] S1. Prepare multifunctional silicone gel. Dissolve Schiff base in liquid epoxy resin to form a saturated solution, then mix 5-20% Schiff base solution, 2-10% gas phase SiO2, 70-90% PDMS and its curing agent to obtain multifunctional silicone gel. The Schiff base is o-vanillin ethylenediamine bis-Schiff base, or is replaced by other nitrogen-containing multidentate ligands; the ligand includes: 1,1',1"-tris[(pyridine-4-oxy)methyl]ethane, 1-(1H-1,2,4-triazolylmethyl)-3,5-bipyridyl-1,2,4-triazole, tris(4-imidazolylphenyl)amine, (4-(1-H-1,2,4-triazolyl)phenyl)amine, 1,1'-(1,4-butyl)bis[2-(2-pyridyl)benzimidazole] or more; the PDMS is one or more of dimethylmethoxysilane, dimethylsiloxane alcohol methyl chain end blocking agent, and dimethylsiloxane chloromethyl chain end blocking agent; the curing agent is one or more of hexamethyldisiloxane, tetrahydrosilanol, and trichloroethylsilanol;

[0033] S2, coating the epoxy resin on the rubber film in a stretched state, releasing the strain after heating and curing, and continuing to coat the epoxy resin in an unstretched state, and peeling off the rubber film after curing to obtain an epoxy film with wrinkles on the surface; the curing heating temperature is 90-110° C., and the heating time is 60 minutes;

[0034] S3, printing the multifunctional silicone gel prepared in S1 on a rubber film by various patterning techniques, covering it with the epoxy film prepared in S2 as a template, heating and curing it, and obtaining a formed silicone gel pattern; the curing heating temperature is 140-160° C., and the heating time is 60 minutes; the rubber film is one or more of a natural rubber film, a polyurethane film, a chloroprene film, and a silicone rubber film;

[0035] S4, immersing the silicone gel pattern prepared in S3 into a saturated silver nitrate ethanol solution to form a catalytic seed layer, thereby obtaining a silicone gel pattern loaded with a catalyst; since the catalyst of the cross-linking reaction of PDMS coordinates with the Schiff base ligand, the silicon-hydrogen bonds in the cross-linking agent molecules after curing are not completely consumed, and thus the silicone gel pattern exhibits a certain degree of reducing property, and the silver ions can be reduced to form a catalytic seed layer, thereby obtaining a multifunctional silicone gel pattern loaded with a catalyst; the immersion time in the silver nitrate ethanol solution is 25-35 minutes;

[0036] S5. The catalyst-loaded silicone gel pattern obtained in S4 is metallized by a chemical copper plating process to obtain a stretchable copper conductive pattern; the composition of the chemical copper plating process plating solution includes copper sulfate, EDTA, sodium hydroxide, potassium sodium tartrate, and the pH is controlled at 12.5 and the temperature is controlled at 45°C.

[0037] Example 1

[0038] Step 1: Dissolve the o-vanillin ethylenediamine bis-Schiff base in liquid epoxy resin and stir with a magnetic stirrer at room temperature until the Schiff base is completely dissolved to form a saturated solution with a concentration of 5.2 g / L. Then, in a clean reaction container, first add 1.0 g of the saturated Schiff base solution, then add 0.5 g of gas-phase SiO2, gently stir with a stirring rod to evenly disperse it in the solution, then add 10 g of dimethylmethoxysilane, continue stirring to ensure that all ingredients are fully mixed. Finally, add 1.0 g of hexamethyldisiloxane, and the mixture begins to cross-link. Stir the mixture at room temperature for a period of time until a uniform multifunctional silicone gel is formed. The prepared silicone gel is cured under appropriate conditions, such as heating or ultraviolet irradiation, to complete the cross-linking process and finally form a multifunctional silicone gel.

[0039] Step 2: Apply epoxy resin on the rubber film in a uniaxially stretched state, then put the rubber film coated with epoxy resin into an oven and heat it at 100°C for 60 minutes. After curing, take the rubber film out of the oven and slowly release the tensile strain. Since the epoxy film has been cured and the rubber film is elastic, releasing the strain will cause the epoxy film to deform and form a wrinkled structure. Continue to apply epoxy resin in an unstretched state, and peel off the rubber film after curing to obtain an epoxy film with wrinkles on the surface.

[0040] Step 3: Print the multifunctional silicone gel prepared in step 1 directly on the stretchable natural rubber film by screen printing technology, and cover it with the epoxy film prepared in step 2 as a template to ensure close contact between the epoxy film and the natural rubber film. Put the covered natural rubber film into an oven and heat it at 150°C for 60 minutes to further cross-link and cure the silicone gel. After heating, take it out and cool it to room temperature, remove the epoxy film template, and obtain a formed silicone gel pattern.

[0041] Step 4: Carefully immerse the silicone gel pattern prepared in step 3 into the silver nitrate ethanol solution, making sure that the pattern is completely immersed in the solution so that the silver nitrate can be evenly deposited on the surface of the silicone gel. During the immersion process, the silver nitrate will gradually be reduced to tiny silver particles, which are evenly distributed on the surface of the silicone gel to form a catalytic seed layer. After the immersion time is over, remove the silicone gel pattern from the silver nitrate ethanol solution. Use deionized water to thoroughly wash the silicone gel pattern to remove excess silver nitrate and ethanol to prevent interference with subsequent steps. The cleaned silicone gel pattern is dried naturally at room temperature or blown dry with nitrogen in preparation for the subsequent metal deposition step.

[0042] Step 5: Metallize the catalyst-loaded silicone gel pattern obtained in step 4 through a chemical copper plating process. The components of the chemical copper plating solution are as follows: 15 g / L copper sulfate, 20 g / L EDTA, 15 g / L sodium hydroxide, 7.5 g / L potassium sodium tartrate, the pH is controlled at 12.5, and the temperature is controlled at 45°C. Thoroughly clean the catalyst-loaded silicone gel pattern to remove surface pollutants and grease. Then immerse the cleaned silicone gel pattern in a pre-prepared chemical copper plating solution. Under controlled temperature and pH conditions, allow the silicone gel pattern to react in the plating solution for a period of time until the copper layer is evenly deposited on the pattern. After the reaction is completed, remove the silicone gel pattern from the plating solution and rinse it with deionized water. The treated silicone gel pattern is dried, and a uniform and dense copper layer is deposited on the silicone gel pattern to form a stretchable copper conductive pattern. Figure 2 As shown, the conductive patterns have good conductivity and stretchability and are suitable for various flexible electronic applications.

[0043] The conductivity was measured by a low resistance meter and was 4.93×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 320.2W / (mK); has excellent tensile properties, through the universal testing machine for tensile test, the unidirectional tensile product strain can reach 190%.

[0044] Example 2

[0045] In step 3 of Example 2, the rubber film is a polyurethane film. The remaining steps are the same as those of Example 1. The conductivity is 3.10×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 291.3W / (mK); has excellent tensile properties, through the universal testing machine tensile test, the unidirectional tensile product strain can reach 161%.

[0046] Example 3

[0047] In step 2 of Example 1, epoxy resin is coated on the rubber film in a multi-axially stretched state, and the remaining steps are the same as those of Example 1. The conductivity is measured by a low resistance meter to be 4.89×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 318.6W / (mK); has excellent tensile properties, through the universal testing machine tensile test, the multi-directional tensile product strain can reach 110%.

[0048] Example 4

[0049] The PDMS used in Example 4 is a dimethylsiloxane methyl chain end blocking agent, and the curing agent is tetrahydrosilanol; the remaining steps are the same as those in Example 1. The conductivity measured by the low resistance meter is 4.75×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 309.3W / (mK); with excellent tensile properties, through the universal testing machine for tensile test, the unidirectional tensile product strain can reach 186%.

[0050] Example 5

[0051] Step 1: Dissolve the o-vanillin ethylenediamine bis-Schiff base in liquid epoxy resin and stir with a magnetic stirrer at room temperature until the Schiff base is completely dissolved to form a saturated solution with a concentration of 5.2 g / L. Then, in a clean reaction container, first add 1.0 g of the saturated Schiff base solution, then add 0.5 g of gas-phase SiO2, gently stir with a stirring rod to evenly disperse it in the solution, then add 10 g of dimethylsiloxane alcohol methyl chain end blocking agent, continue stirring to ensure that all ingredients are fully mixed. Finally, add 1.0 g of tetrahydrosilanol, and the mixture begins to cross-link. Stir the mixture at room temperature for a period of time until a uniform multifunctional silicone gel is formed. Cure the prepared silicone gel under appropriate conditions, such as heating or ultraviolet irradiation, to complete the cross-linking process. Finally, a multifunctional silicone gel is formed.

[0052] Step 2: Apply epoxy resin on the rubber film in a uniaxially stretched state, then put the rubber film coated with epoxy resin into an oven and heat it at 90°C for 50 minutes. After curing, take the rubber film out of the oven and slowly release the tensile strain. Since the epoxy film has been cured and the rubber film is elastic, releasing the strain will cause the epoxy film to deform and form a wrinkled structure. Continue to apply epoxy resin in an unstretched state, and peel off the rubber film after curing to obtain an epoxy film with wrinkles on the surface.

[0053] Step 3: Print the multifunctional silicone gel prepared in step 1 directly on the stretchable chloroprene film by screen printing technology, and cover it with the epoxy film prepared in step 2 as a template to ensure close contact between the epoxy film and the chloroprene film. Put the covered chloroprene film into an oven and heat it at 160°C for 70 minutes to further cross-link and cure the silicone gel. After heating, take it out and cool it to room temperature, remove the epoxy film template, and obtain a formed silicone gel pattern.

[0054] Step 4: Carefully immerse the silicone gel pattern prepared in step 3 in the silver nitrate ethanol solution for 25 minutes, making sure the pattern is completely immersed in the solution so that the silver nitrate can be evenly deposited on the surface of the silicone gel. During the soaking process, the silver nitrate will gradually be reduced to tiny silver particles, which are evenly distributed on the surface of the silicone gel to form a catalytic seed layer. After the soaking time is over, remove the silicone gel pattern from the silver nitrate ethanol solution. Use deionized water to thoroughly wash the silicone gel pattern to remove excess silver nitrate and ethanol to prevent interference with subsequent steps. The cleaned silicone gel pattern is dried naturally at room temperature or blown dry with nitrogen in preparation for the subsequent metal deposition step.

[0055] Step 5: The catalyst-loaded silicone gel pattern obtained in step 4 is metalized by chemical copper plating process. The components of the chemical copper plating process plating solution are as follows: 15g / L copper sulfate, 20g / L EDTA, 15g / L sodium hydroxide, 7.5g / L potassium sodium tartrate, pH is controlled at 12.5, and the temperature is controlled at 45°C. Clean the catalyst-loaded silicone gel pattern thoroughly to remove surface pollutants and grease. Then immerse the cleaned silicone gel pattern in the pre-prepared chemical copper plating solution. Under controlled temperature and pH conditions, let the silicone gel pattern react in the plating solution for a period of time until the copper layer is evenly deposited on the pattern. After the reaction is completed, remove the silicone gel pattern from the plating solution and rinse it with deionized water. The treated silicone gel pattern is dried, and a uniform and dense copper layer is deposited on the silicone gel pattern to form a stretchable copper conductive pattern. The conductivity is measured by a low resistance meter to be 2.73×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 283.6W / (mK); has excellent tensile properties, through the universal testing machine tensile test, the unidirectional tensile product strain can reach 145%.

[0056] Example 6

[0057] Step 1: Dissolve the o-vanillin ethylenediamine bis-Schiff base in liquid epoxy resin and stir with a magnetic stirrer at room temperature until the Schiff base is completely dissolved to form a saturated solution with a concentration of 5.2 g / L. Then, in a clean reaction container, first add 1.0 g of the saturated Schiff base solution, then add 0.5 g of gas-phase SiO2, gently stir with a stirring rod to evenly disperse it in the solution, then add 10 g of dimethylmethoxysilane, continue stirring to ensure that all ingredients are fully mixed. Finally, add 1.0 g of trichloroethylsilanol, and the mixture begins to crosslink. Stir the mixture at room temperature for a period of time until a uniform multifunctional silicone gel is formed. Cure the prepared silicone gel under appropriate conditions, such as heating or ultraviolet irradiation, to complete the crosslinking process. Finally, a multifunctional silicone gel is formed.

[0058] Step 2: Apply epoxy resin on the rubber film in a uniaxially stretched state, then put the rubber film coated with epoxy resin into an oven and heat it at 110°C for 70 minutes. After curing, take the rubber film out of the oven and slowly release the tensile strain. Since the epoxy film has been cured and the rubber film is elastic, releasing the strain will cause the epoxy film to deform and form a wrinkled structure. Continue to apply epoxy resin in an unstretched state, and peel off the rubber film after curing to obtain an epoxy film with wrinkles on the surface.

[0059] Step 3: Print the multifunctional silicone gel prepared in step 1 directly on the stretchable silicone rubber film by screen printing technology, and cover it with the epoxy film prepared in step 2 as a template to ensure close contact between the epoxy film and the silicone rubber film. Put the covered silicone rubber film into an oven and heat it at 140°C for 50 minutes to further cross-link and cure the silicone gel. After heating, take it out and cool it to room temperature, remove the epoxy film template, and obtain a formed silicone gel pattern.

[0060] Step 4: Carefully immerse the silicone gel pattern prepared in step 3 in the silver nitrate ethanol solution for 35 minutes, making sure the pattern is completely immersed in the solution so that the silver nitrate can be evenly deposited on the surface of the silicone gel. During the soaking process, the silver nitrate will gradually be reduced to tiny silver particles, which are evenly distributed on the surface of the silicone gel to form a catalytic seed layer. After the soaking time is over, remove the silicone gel pattern from the silver nitrate ethanol solution. Use deionized water to thoroughly wash the silicone gel pattern to remove excess silver nitrate and ethanol to prevent interference with subsequent steps. The cleaned silicone gel pattern is dried naturally at room temperature or blown dry with nitrogen in preparation for the subsequent metal deposition step.

[0061] Step 5: The catalyst-loaded silicone gel pattern obtained in step 4 is metalized by chemical copper plating process. The components of the chemical copper plating process plating solution are as follows: 15g / L copper sulfate, 20g / L EDTA, 15g / L sodium hydroxide, 7.5g / L potassium sodium tartrate, pH is controlled at 12.5, and the temperature is controlled at 45°C. Thoroughly clean the catalyst-loaded silicone gel pattern to remove surface pollutants and grease. Then immerse the cleaned silicone gel pattern in the pre-prepared chemical copper plating solution. Under controlled temperature and pH conditions, let the silicone gel pattern react in the plating solution for a period of time until the copper layer is evenly deposited on the pattern. After the reaction is completed, remove the silicone gel pattern from the plating solution and rinse it with deionized water. The treated silicone gel pattern is dried, and a uniform and dense copper layer is deposited on the silicone gel pattern to form a stretchable copper conductive pattern. The conductivity is measured by a low resistance meter to be 4.63×10 7 Sm -1 , close to the theoretical value of pure copper block 304.7W / (mK); good thermal conductivity, measured by laser flash meter, its thermal conductivity is; has excellent tensile properties, through the universal testing machine for tensile test, unidirectional tensile product strain can reach 185%.

[0062] Example 7

[0063] In step 1 of Example 7, 1.5 g of gas-phase SiO2 was added to improve the viscosity of the multifunctional gel. The remaining steps were the same as those of Example 1. The conductivity was measured by a low resistance meter and was 4.84×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 313.2W / (mK); has excellent tensile properties, through the universal testing machine tensile test, the unidirectional tensile product strain can reach 191%.

[0064] Example 8

[0065] In step 3 of Example 8, the curing heating time is 90 minutes, which improves the viscosity of the multifunctional gel. The remaining steps are the same as those of Example 1. The conductivity measured by the low resistance meter is 4.90×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 315.7W / (mK); with excellent tensile properties, through the universal testing machine for tensile test, the unidirectional tensile product strain can reach 190.4%.

[0066] Figure 1 The flowchart of this application is Figure 2 A photo of a copper conductive pattern. Figure 3As shown in the figure, the copper conductive pattern prepared by the present invention has a dense surface without any cracks or voids. Figure 4 As shown, the XRD spectrum of the copper conductive pattern prepared by the present invention matches well with the standard XRD data of cubic copper, and no peaks of other impurities are detected. Figure 5 As shown, the conductivity of the copper conductive pattern prepared by the present invention is comparable to that of commercial copper foil and has extremely high conductivity. Figure 6 As shown, the thermal conductivity of the copper conductive pattern prepared by the present invention is comparable to that of copper foil, and has good thermal conductivity.

[0067] Comparative Example 1

[0068] The multifunctional silica gel in the present invention was replaced by a common composite catalytic silica gel (containing silver particles and no special ligands). A printed circuit was prepared according to steps S3 to S5 of the present invention. The conductivity of the obtained circuit was measured to be 5.12×10 6 Sm -1 , thermal conductivity is 279.6W / (mK), and it cannot be stretched.

[0069] Depend on Figure 7 It can be seen that the copper conductive pattern prepared by using the common composite catalytic silica gel is unevenly distributed and has bubbles compared with the copper conductive pattern in Example 1. The stretchable metal copper pattern obtained by the present invention has excellent electrical, thermal and mechanical properties, and the prepared copper pattern has a compact structure. The conductivity measured by the low resistance meter is 4.93×10 7 Sm -1 , close to the theoretical value of pure copper block; good thermal conductivity, measured by laser flash meter, its thermal conductivity is 320.2W / (mK); has excellent tensile properties, through the universal testing machine for tensile test, the unidirectional tensile product strain can reach 190%.

[0070] Therefore, the present application provides a stretchable metal-based electrical / thermal conductor, which for the first time realizes the construction of a multi-directionally stretchable printed circuit on a normal (not pre-stretched) flat substrate by introducing a medium layer (multifunctional silicone gel) strategy, thereby realizing a new product that combines the advantages of traditional "in-plane" and "out-of-plane" stretching structures, and promoting the development and application of structural stretch circuits.

[0071] In the description of this specification, the description with reference to the terms "an experimental example", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the experimental example or example are included in at least one experimental example or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same experimental example or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more experimental examples or examples in a suitable manner.

[0072] Finally, it should be noted that the above experimental examples are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred experimental examples, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A stretchable metal-based electrical / thermal conductor, characterized in that: The method comprises the following preparation steps: S1, configure multifunctional silicone gel; S2, configuring an epoxy film with wrinkles on the surface; S3, printing the multifunctional silicone gel prepared in S1 on a rubber film by various patterning techniques, covering it with the epoxy film prepared in S2 as a template, heating and curing it, and obtaining a molded silicone gel pattern; S4, immersing the silica gel pattern prepared in S3 into a saturated silver nitrate ethanol solution to form a catalytic seed layer, thereby obtaining a silica gel pattern loaded with a catalyst; S5. The catalyst-loaded silica gel pattern obtained in S4 is metallized by a chemical copper plating process to obtain a stretchable copper conductive pattern.

2. A stretchable metal-based electrical / thermal conductor according to claim 1, characterized in that: The specific steps of step S1 are: mixing 5-20% Schiff base solution, 2-10% gas phase SiO2, 70-90% PDMS and a curing agent to obtain a multifunctional silicone gel.

3. A stretchable metal-based electrical / thermal conductor according to claim 1, characterized in that: The specific steps of step S2 are: coating epoxy resin on the rubber film in a stretched state, releasing the strain after heating and curing, continuing to coat the epoxy resin in an unstretched state, and peeling off the rubber film after curing to obtain an epoxy film with wrinkles on the surface.

4. A stretchable metal-based electrical / thermal conductor according to claim 2, characterized in that: In S1, the Schiff base solution is a saturated solution formed by dissolving the Schiff base in the liquid epoxy resin; The Schiff base is o-vanillin ethylenediamine bis-Schiff base, or is replaced by other nitrogen-containing multidentate ligands; the ligands include: 1,1',1"-tris[(pyridine-4-oxy)methyl]ethane, 1-(1H-1,2,4-triazolylmethyl)-3,5-bipyridyl-1,2,4-triazole, tris(4-imidazolylphenyl)amine, (4-(1-H-1,2,4-triazolyl)phenyl)amine, 1,1'-(1,4-butyl)bis[2-(2-pyridyl)benzimidazole] or one or more thereof.

5. A stretchable metal-based electrical / thermal conductor according to claim 2, characterized in that: In S1, the PDMS is one or more of dimethylmethoxysilane, dimethylsiloxane alcohol methyl chain end blocking agent, and dimethylsiloxane chloromethyl chain end blocking agent.

6. A stretchable metal-based electrical / thermal conductor according to claim 2, characterized in that: In S1, the curing agent is one or more of hexamethyldisiloxane, tetrahydrosilanol, and trichloroethylsilanol.

7. The method for preparing a stretchable metal-based electrical / thermal conductor according to claim 3, characterized in that: In the S2, the curing heating temperature is 90-110° C., and the heating time is 50-70 minutes.

8. The method for preparing a stretchable metal-based electrical / thermal conductor according to claim 1, characterized in that: In S3, the curing heating temperature is 140-160° C., and the heating time is 50-70 minutes; the rubber film is one or more of a natural rubber film, a polyurethane film, a chloroprene film, and a silicone rubber film.

9. The method for preparing a stretchable metal-based electrical / thermal conductor according to claim 1, characterized in that: In the step S4, the immersion time in the silver nitrate ethanol solution is 25-35 minutes.

10. The method for preparing a stretchable metal-based electrical / thermal conductor according to claim 1, characterized in that: In S5, the composition of the electroless copper plating process plating solution includes copper sulfate, EDTA, sodium hydroxide, potassium sodium tartrate, the pH is controlled at 12.5, and the temperature is controlled at 45°C.

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