Corrosion-resistant and temperature shock-resistant composite layer and application thereof in terminal preparation

Abstract

The invention discloses a corrosion-resistant and temperature-shock-resistant composite layer and application thereof in terminal preparation, the corrosion-resistant and temperature-shock-resistant composite layer comprises a bottom layer, a middle layer and a surface layer, the middle layer is arranged on the upper surface of the bottom layer, the surface layer is arranged on the upper surface of the middle layer, the bottom layer is a non-porous nickel bottom layer arranged on the surface of a base material, and the surface layer is a non-porous nickel bottom layer arranged on the surface of the base material. The middle layer is a silver plating layer or a silver alloy plating layer, the surface comprises a palladium-nickel plating layer and a gold layer arranged on the upper surface of the palladium-nickel plating layer, and electroplating liquid of the non-porous nickel bottom layer comprises the following raw materials of 80-140 g / L of nickel ions, 0-15 g / L of nickel chloride, 35-45 g / L of boric acid and 0.1-0.25 g / L of a first additive; the first additive is an ampholytic surfactant. The zwitterionic surfactant is adopted as the electroplating liquid of the nickel bottom layer to prepare the pore-free nickel bottom layer, so that the corrosion resistance of the nickel bottom layer and the copper substrate is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of corrosion-resistant and temperature-shock-resistant composite layers, and in particular relates to a corrosion-resistant and temperature-shock-resistant composite layer and an application thereof in preparing a terminal. Background Art

[0002] When the electrical connector terminals of the Micro-USB, Type-C and other mobile phone USB connector charging ports are exposed to sweat or water / salt water / seawater during use, the positive electrode of the electrical connector terminal will be subjected to anodic electrolysis during the charging process, and the surface plating layer will quickly corrode, even to the nickel base and copper base, which will increase the contact resistance and cause open circuit and functional and application problems. This is a problem that has plagued the industry for many years and cannot be solved.

[0003] At present, the electroplating specifications of USB / TpceC connectors in the industry are mostly Ni80u”min+30u”minHard Au. According to laboratory tests and research, in artificial sweat (containing 5% NaCl), 5V anode electrolysis for 2 minutes, Au and Ni plating are completely peeled off; for 80u”Ni+50u”Hard Au plating, the Au plating begins to dissolve under the same conditions for 3 minutes, and the bottom nickel and copper substrate also begin to corrode. The above tests show that the thickness of Au has a significant effect on sweat electrolysis. The thicker the thickness, the stronger the ability to resist electrolytic corrosion; even if the 50u”Au” sample is tested, the time of anti-electrolytic corrosion is ≤3 minutes, which is far from the expected performance.

[0004] In order to solve the corrosion problem of nickel and copper substrates, the prior art uses anionic surfactants as the electroplating solution of the nickel substrate to prepare a non-porous nickel substrate, thereby improving the corrosion resistance of the nickel and copper substrates. However, the improvement of the corrosion resistance of the nickel and copper substrates is limited. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, a corrosion-resistant and temperature-shock-resistant composite layer is provided, comprising a bottom layer, an intermediate layer and a surface layer, wherein the intermediate layer is arranged on the upper surface of the bottom layer, the surface layer is arranged on the upper surface of the intermediate layer, the bottom layer is a non-porous nickel bottom layer arranged on the surface of the substrate, the intermediate layer is a silver plating layer or a silver alloy plating layer, the surface comprises a palladium nickel plating layer and a gold layer arranged on the upper surface of the palladium nickel plating layer, and the electroplating solution of the non-porous nickel bottom layer comprises raw materials of the following concentrations: nickel ions 80-140 g / L, nickel chloride 0-15 g / L, boric acid 35-45 g / L, and a first additive 0.1-0.25 g / L; the first additive is an amphoteric surfactant. The non-porous nickel bottom layer is prepared by using amphoteric surfactant as the electroplating solution of the nickel bottom layer, which effectively improves the corrosion resistance of the nickel bottom layer and the copper substrate.

[0006] The object of the present invention is to provide a corrosion-resistant and temperature-shock-resistant composite layer, comprising a bottom layer, an intermediate layer and a surface layer, wherein the intermediate layer is arranged on the upper surface of the bottom layer, and the surface layer is arranged on the upper surface of the intermediate layer. The bottom layer is a non-porous nickel bottom layer arranged on the surface of a substrate, the intermediate layer is a silver plating layer or a silver alloy plating layer, and the surface comprises a palladium nickel plating layer and a gold layer arranged on the upper surface of the palladium nickel plating layer. The electroplating solution of the non-porous nickel bottom layer comprises raw materials with the following concentrations: nickel ions 80-140 g / L, nickel chloride 0-15 g / L, boric acid 35-45 g / L, and a first additive 0.1-0.25 g / L; the first additive is an amphoteric surfactant.

[0007] The present invention adopts a zwitterionic surfactant as the electroplating solution of the nickel bottom layer to prepare the non-porous nickel bottom layer. The zwitterionic surfactant contains positive and negative ions, which are respectively combined with the positive and negative ions in the electroplating solution, which is beneficial to enhancing the interaction between substances, thereby reducing the porosity of the nickel bottom layer, and then obtaining the non-porous nickel bottom layer, and effectively improving the corrosion resistance of the nickel bottom layer and the copper substrate.

[0008] In some embodiments of the present invention, the amphoteric surfactant is selected from quaternary ammonium salt amphoteric surfactants or betaine amphoteric surfactants.

[0009] In some embodiments of the present invention, the quaternary ammonium salt amphoteric surfactant is selected from long-chain alkyl quaternary ammonium salt amphoteric surfactants.

[0010] In some embodiments of the present invention, the structure of the long-chain alkyl quaternary ammonium salt amphoteric surfactant is as follows:

[0011] Wherein, the R is an alkyl group with 12 to 18 carbon atoms.

[0012] In some embodiments of the present invention, the nickel ion is nickel sulfamate.

[0013] In some embodiments of the present invention, the pH value of the electroplating solution of the non-porous nickel bottom layer is 3-4.5, the nickel plating temperature is 55-65° C., the cathode current density is 5-20 ASD, the electroplating time is 1-2 min, and the coating thickness is 2.0-5.0 μm.

[0014] In some embodiments of the present invention, the thickness of the intermediate layer is 0.2-0.5 μm.

[0015] In some embodiments of the present invention, the palladium-nickel plating layer has a thickness of 1-3 μm.

[0016] In some embodiments of the present invention, the thickness of the gold layer is 0.03-0.3 μm.

[0017] In some embodiments of the present invention, the electroplating solution of the palladium-nickel plating layer includes raw materials with the following concentrations: palladium ions 4-25 g / L, nickel ions 0.5-10 g / L, conductive salt 20-70 g / L, and a second additive 2-8 g / L; the nickel ions are at least one of nickel sulfate or nickel chloride.

[0018] In some embodiments of the present invention, the second additive is selected from at least one of sodium vinyl sulfonate and sodium propylene sulfonate.

[0019] In some embodiments of the present invention, the conductive salt is at least one of potassium sulfate and potassium chloride.

[0020] In some embodiments of the present invention, the palladium ion is one of palladium chloride and palladium nitrate.

[0021] In some embodiments of the present invention, the palladium content of the palladium nickel coating is 80-90wt%.

[0022] In some embodiments of the present invention, the pH value of the electroplating solution of the palladium-nickel plating layer is 7-9, and the electroplating cathode current density is 0.5-10A / dm 2 , the electroplating temperature is 40-50℃.

[0023] In some embodiments of the present invention, the surface layer further includes a lubricating layer, the lubricating layer is disposed on the upper surface of the gold layer, and the lubricating layer is formed by coating with a lubricating layer material.

[0024] In some embodiments of the present invention, the material of the lubricating layer is selected from octa(aminophenyltrioxysilane).

[0025] The present invention adopts octa(aminophenyltrioxysilane) as the material of the lubricating layer, thereby effectively improving the wear resistance of the palladium nickel plating layer, so that the corrosion-resistant and temperature-shock-resistant composite layer can still maintain good salt water anode electrolytic corrosion resistance after multiple plug-in tests or use.

[0026] In some embodiments of the present invention, the substrate is copper or a copper alloy.

[0027] Another object of the present invention is to provide a method for preparing the corrosion-resistant and temperature-shock-resistant composite layer, comprising the following steps: S1. Electroplating the substrate surface with a non-porous nickel bottom layer using a plating solution to form a non-porous nickel bottom layer; S2. electroplating an intermediate layer on the upper surface of the non-porous nickel bottom layer; S3. Electroplating the palladium-nickel coating with a plating solution on the upper surface of the intermediate layer to form a palladium-nickel coating; S4. Electroplating a gold layer on the upper surface of the palladium-nickel plated layer, coating a layer of lubricating oil on the surface of the gold layer to form a lubricating protective coating, thereby obtaining a corrosion-resistant and temperature-shock-resistant composite layer. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] Example 1 This embodiment provides a corrosion-resistant and temperature-shock-resistant composite layer, and the specific preparation steps are as follows: S1. Electroplating a non-porous nickel bottom layer on the copper surface with a non-porous nickel bottom layer; the non-porous nickel bottom layer electroplating solution comprises raw materials of the following concentrations: 80 g / L nickel sulfamate, 15 g / L nickel chloride, 35 g / L boric acid, and 0.25 g / L lauramide propyl hydroxysulfobetaine; the pH value of the non-porous nickel bottom layer electroplating solution is 3, the nickel plating temperature is 65°C, the cathode current density is 5 ASD, the electroplating time is 2 min, and the coating thickness is 2.0 μm; S2. A silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver coating is 0.5 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials in the following concentrations: 4g / L palladium chloride, 10g / L nickel sulfate, 70g / L potassium sulfate, and 2g / L sodium vinyl sulfonate; the palladium content of the palladium-nickel plating layer is 80wt%; the pH value of the palladium-nickel plating solution is 7, and the electroplating cathode current density is 10A / dm 2 , the electroplating temperature is 40° C.; the thickness of the palladium-nickel plating layer is 1 μm; S4. A gold layer is electroplated on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.03 μm, and a layer of octa(aminophenyltrioxysilane) is brushed on the surface of the gold layer to form a lubricating protective coating to obtain a corrosion-resistant and temperature-shock-resistant composite layer.

[0030] Example 2 This embodiment provides a corrosion-resistant and temperature-shock-resistant composite layer, and the specific preparation steps are as follows: S1. Electroplating the copper surface with a non-porous nickel bottom layer using a non-porous nickel bottom layer electroplating solution to form a non-porous nickel bottom layer; the non-porous nickel bottom layer electroplating solution comprises raw materials of the following concentrations: 140 g / L nickel sulfamate, 45 g / L boric acid, and 0.1 g / L lauramide propyl hydroxysulfobetaine; the pH value of the non-porous nickel bottom layer electroplating solution is 4.5, the nickel plating temperature is 55°C, the cathode current density is 20 ASD, the electroplating time is 1 min, and the coating thickness is 5.0 μm; S2. The silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver alloy coating is 0.2 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver alloy plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials in the following concentrations: 25 g / L palladium nitrate, 0.5 g / L nickel chloride, 20 g / L potassium chloride, and 8 g / L sodium propylene sulfonate; the palladium content of the palladium-nickel plating layer is 90 wt %; the pH value of the palladium-nickel plating solution is 9, and the electroplating cathode current density is 0.5 A / dm 2 , the electroplating temperature is 50° C.; the thickness of the palladium-nickel plating layer is 3 μm; S4. A gold layer is electroplated on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.3 μm, and a layer of octa(aminophenyltrioxysilane) is brushed on the surface of the gold layer to form a lubricating protective coating to obtain a corrosion-resistant and temperature-shock-resistant composite layer.

[0031] Example 3 This embodiment provides a corrosion-resistant and temperature-shock-resistant composite layer, and the specific preparation steps are as follows: S1. Electroplating a copper surface with a non-porous nickel bottom layer using a non-porous nickel bottom layer electroplating solution to form a non-porous nickel bottom layer; the non-porous nickel bottom layer electroplating solution comprises raw materials of the following concentrations: 100 g / L nickel sulfamate, 10 g / L nickel chloride, 40 g / L boric acid, and 0.15 g / L lauramide propyl hydroxysulfobetaine; the pH value of the non-porous nickel bottom layer electroplating solution is 4, the nickel plating temperature is 60°C, the cathode current density is 10 ASD, the electroplating time is 1.5 min, and the coating thickness is 3.5 μm; S2. The silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver alloy coating is 0.4 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver alloy plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials: 15g / L palladium nitrate, 5g / L nickel chloride, 40g / L potassium chloride, 5g / L sodium propylene sulfonate; the palladium content of the palladium-nickel plating layer is 85wt%; the pH value of the palladium-nickel plating solution is 8, and the electroplating cathode current density is 5A / dm 2 , the electroplating temperature is 45° C.; the thickness of the palladium nickel plating layer is 2 μm; S4. A gold layer is electroplated on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.15 μm, and a layer of octa(aminophenyltrioxysilane) is brushed on the surface of the gold layer to form a lubricating protective coating to obtain a corrosion-resistant and temperature-shock-resistant composite layer.

[0032] Example 4 This embodiment provides a corrosion-resistant and temperature-shock-resistant composite layer, which is different from the embodiment 3 only in that the lauramide propyl hydroxysulfobetaine in the embodiment 3 is replaced by a long-chain alkyl quaternary ammonium salt amphoteric surfactant. The specific preparation steps are as follows: S1. Electroplating the copper surface with a non-porous nickel bottom layer using a non-porous nickel bottom layer plating solution to form a non-porous nickel bottom layer; the non-porous nickel bottom layer plating solution comprises the following raw materials: 100 g / L nickel sulfamate, 10 g / L nickel chloride, 40 g / L boric acid, and 0.15 g / L long-chain alkyl quaternary ammonium salt amphoteric surfactant; the pH value of the non-porous nickel bottom layer plating solution is 4, the nickel plating temperature is 60°C, the cathode current density is 10 ASD, the plating time is 1.5 min, and the coating thickness is 3.5 μm; the structure of the long-chain alkyl quaternary ammonium salt amphoteric surfactant is as follows:

[0033] Wherein, R is an alkyl group with 12 carbon atoms; S2. The silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver alloy coating is 0.4 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver alloy plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials: 15g / L palladium nitrate, 5g / L nickel chloride, 40g / L potassium chloride, 5g / L sodium propylene sulfonate; the palladium content of the palladium-nickel plating layer is 85wt%; the pH value of the palladium-nickel plating solution is 8, and the electroplating cathode current density is 5A / dm 2 , the electroplating temperature is 45° C.; the thickness of the palladium nickel plating layer is 2 μm; S4. A gold layer is electroplated on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.15 μm, and a layer of octa(aminophenyltrioxysilane) is brushed on the surface of the gold layer to form a lubricating protective coating to obtain a corrosion-resistant and temperature-shock-resistant composite layer.

[0034] Example 5 This embodiment provides a corrosion-resistant and temperature-shock-resistant composite layer, which is different from Embodiment 4 only in the structure of the long-chain alkyl quaternary ammonium salt amphoteric surfactant. The specific preparation steps are as follows: S1. Electroplating the copper surface with a non-porous nickel bottom layer using a non-porous nickel bottom layer plating solution to form a non-porous nickel bottom layer; the non-porous nickel bottom layer plating solution comprises the following raw materials: 100 g / L nickel sulfamate, 10 g / L nickel chloride, 40 g / L boric acid, and 0.15 g / L long-chain alkyl quaternary ammonium salt amphoteric surfactant; the pH value of the non-porous nickel bottom layer plating solution is 4, the nickel plating temperature is 60°C, the cathode current density is 10 ASD, the plating time is 1.5 min, and the coating thickness is 3.5 μm; the structure of the long-chain alkyl quaternary ammonium salt amphoteric surfactant is as follows:

[0035] Wherein, R is an alkyl group with 18 carbon atoms; S2. The silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver alloy coating is 0.4 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver alloy plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials: 15g / L palladium nitrate, 5g / L nickel chloride, 40g / L potassium chloride, 5g / L sodium propylene sulfonate; the palladium content of the palladium-nickel plating layer is 85wt%; the pH value of the palladium-nickel plating solution is 8, and the electroplating cathode current density is 5A / dm 2 , the electroplating temperature is 45° C.; the thickness of the palladium nickel plating layer is 2 μm; S4. A gold layer is electroplated on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.15 μm, and a layer of octa(aminophenyltrioxysilane) is brushed on the surface of the gold layer to form a lubricating protective coating to obtain a corrosion-resistant and temperature-shock-resistant composite layer.

[0036] Example 6 This embodiment provides a corrosion-resistant and temperature-shock-resistant composite layer, which differs from Embodiment 3 only in that it does not contain a lubricating layer. The specific preparation steps are as follows: S1. Electroplating a copper surface with a non-porous nickel bottom layer using a non-porous nickel bottom layer electroplating solution to form a non-porous nickel bottom layer; the non-porous nickel bottom layer electroplating solution comprises raw materials of the following concentrations: 100 g / L nickel sulfamate, 10 g / L nickel chloride, 40 g / L boric acid, and 0.15 g / L lauramide propyl hydroxysulfobetaine; the pH value of the non-porous nickel bottom layer electroplating solution is 4, the nickel plating temperature is 60°C, the cathode current density is 10 ASD, the electroplating time is 1.5 min, and the coating thickness is 3.5 μm; S2. The silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver alloy coating is 0.4 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver alloy plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials: 15g / L palladium nitrate, 5g / L nickel chloride, 40g / L potassium chloride, 5g / L sodium propylene sulfonate; the palladium content of the palladium-nickel plating layer is 85wt%; the pH value of the palladium-nickel plating solution is 8, and the electroplating cathode current density is 5A / dm 2 , the electroplating temperature is 45° C.; the thickness of the palladium nickel plating layer is 2 μm; S4. Electroplating a gold layer on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.15 μm, thereby obtaining a corrosion-resistant and temperature-shock-resistant composite layer.

[0037] Comparative Example 1 This comparative example provides a corrosion-resistant and temperature-shock-resistant composite layer, which is different from Example 3 only in that lauramide propyl hydroxysulfobetaine is replaced with sodium dodecyl sulfate. The specific preparation steps are as follows: S1. Electroplating the copper surface with a non-porous nickel bottom layer using a non-porous nickel bottom layer electroplating solution to form a non-porous nickel bottom layer; the non-porous nickel bottom layer electroplating solution comprises raw materials of the following concentrations: 100 g / L nickel sulfamate, 10 g / L nickel chloride, 40 g / L boric acid, and 0.15 g / L sodium dodecyl sulfonate; the pH value of the non-porous nickel bottom layer electroplating solution is 4, the nickel plating temperature is 60°C, the cathode current density is 10 ASD, the electroplating time is 1.5 min, and the coating thickness is 3.5 μm; S2. The silver coating is electroplated on the upper surface of the non-porous nickel substrate, wherein the thickness of the silver alloy coating is 0.4 μm; S3. Use a palladium-nickel plating solution to electroplate on the upper surface of the silver alloy plating layer to form a palladium-nickel plating layer; the palladium-nickel plating solution is composed of the following raw materials: 15g / L palladium nitrate, 5g / L nickel chloride, 40g / L potassium chloride, 5g / L sodium propylene sulfonate; the palladium content of the palladium-nickel plating layer is 85wt%; the pH value of the palladium-nickel plating solution is 8, and the electroplating cathode current density is 5A / dm 2 , the electroplating temperature is 45° C.; the thickness of the palladium nickel plating layer is 2 μm; S4. A gold layer is electroplated on the upper surface of the palladium-nickel plated layer, wherein the thickness of the gold layer is 0.15 μm, and a layer of octa(aminophenyltrioxysilane) is brushed on the surface of the gold layer to form a lubricating protective coating to obtain a corrosion-resistant and temperature-shock-resistant composite layer.

[0038] Performance Testing: The corrosion-resistant and temperature-shock-resistant composite layers of Examples 1 to 6 and Comparative Example 1 were used as anodes for corrosion resistance tests, respectively. The test conditions were: 5wt% sodium chloride, 40°C, magnetic stirring 200RPM, a platinum-titanium sheet as cathode, the test functional area was exposed, and other areas were sealed with epoxy resin; the distance between the cathode and the anode was 15mm, and the anode voltage was a constant voltage of 5V. When the first corrosion point exceeding 0.05mm was observed in the functional area of ​​the sample, the test was terminated, and the time was recorded, which was the salt water anode electrolytic corrosion tolerance time; The corrosion-resistant and temperature-shock-resistant composite layers of Examples 1 to 6 and Comparative Example 1 were respectively assembled into Type C male connectors, mated with Type C female connectors, and subjected to 1000 manual plug-in and pull-out tests, respectively observing whether the contact functional areas of the corrosion-resistant and temperature-shock-resistant composite layers of Examples 1 to 6 and Comparative Example 1 had obvious scratches and wear; and corrosion resistance tests were conducted, and the test conditions were: sodium chloride 5wt%, temperature 40°C, magnetic stirring 200RPM, cathode platinum titanium sheet, test functional area exposed, other areas sealed with epoxy resin; cathode-cathode distance 15mm, anode voltage constant 5V. When the first corrosion point exceeding 0.05mm was observed in the functional area of ​​the sample, the test was terminated, and the time was recorded, which was the salt water anode electrolytic corrosion tolerance time; the results are shown in Table 1.

[0039] Table 1. Salt water anode electrolytic corrosion resistance test results of the corrosion-resistant and temperature shock-resistant composite layer.

[0040]

[0041] It can be seen from Table 1 that the corrosion-resistant and temperature-shock-resistant composite layers of Examples 1 to 6 of the present invention have good corrosion resistance, wear resistance and damage resistance.

[0042] Finally, it should be noted that the above embodiments 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 above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, the technicians can still modify or replace the specific implementation mode of the present invention with equivalents, but these modifications or changes do not deviate from the scope of protection of the pending claims of the present application.

Claims

1. A corrosion-resistant and temperature-shock-resistant composite layer, characterized in that: The invention comprises a bottom layer, an intermediate layer and a surface layer, wherein the intermediate layer is arranged on the upper surface of the bottom layer, and the surface layer is arranged on the upper surface of the intermediate layer. The bottom layer is a non-porous nickel bottom layer arranged on the surface of a substrate, the intermediate layer is a silver plating layer or a silver alloy plating layer, and the surface comprises a palladium nickel plating layer and a gold layer arranged on the upper surface of the palladium nickel plating layer. The electroplating solution of the non-porous nickel bottom layer comprises raw materials of the following concentrations: 80-140 g / L of nickel ions, 0-15 g / L of nickel chloride, 35-45 g / L of boric acid, and 0.1-0.25 g / L of a first additive; and the first additive is an amphoteric surfactant.

2. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The amphoteric surfactant is selected from quaternary ammonium salt amphoteric surfactants or betaine type amphoteric surfactants.

3. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 2, characterized in that: The quaternary ammonium salt amphoteric surfactant is selected from a long-chain alkyl quaternary ammonium salt amphoteric surfactant, and the structure of the long-chain alkyl quaternary ammonium salt amphoteric surfactant is as follows: ； Wherein, the R is an alkyl group with 12 to 18 carbon atoms.

4. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The nickel ion is nickel sulfamate; the pH value of the electroplating solution of the non-porous nickel bottom layer is 3-4.5, the nickel plating temperature is 55-65° C., the cathode current density is 5-20 ASD, the electroplating time is 1-2 min, and the coating thickness is 2.0-5.0 μm.

5. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The thickness of the intermediate layer is 0.2-0.5 μm, the thickness of the palladium-nickel plating layer is 1-3 μm, and the thickness of the gold layer is 0.03-0.3 μm.

6. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The electroplating solution of the palladium-nickel plating layer comprises raw materials of the following concentrations: 4-25 g / L of palladium ions, 0.5-10 g / L of nickel ions, 20-70 g / L of conductive salt, and 2-8 g / L of a second additive; the nickel ions are at least one of nickel sulfate or nickel chloride; And / or, the second additive is selected from at least one of sodium vinyl sulfonate and sodium propylene sulfonate; And / or, the conductive salt is at least one of potassium sulfate and potassium chloride; And / or, the palladium ion is one of palladium chloride and palladium nitrate.

7. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The palladium content of the palladium nickel coating is 80-90wt%; And / or, the pH value of the electroplating solution of the palladium nickel plating layer is 7-9, and the electroplating cathode current density is 0.5-10A / dm 2 , the electroplating temperature is 40-50℃.

8. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The surface layer also includes a lubricating layer, which is arranged on the upper surface of the gold layer. The lubricating layer is coated with a lubricating layer material, and the lubricating layer material is selected from octa(aminophenyltrisilane).

9. The corrosion-resistant and temperature-shock-resistant composite layer according to claim 1, characterized in that: The substrate is copper or a copper alloy.

10. The method for preparing the corrosion-resistant and temperature-shock-resistant composite layer according to any one of claims 1 to 9, characterized in that: The steps include: S1. Electroplating the substrate surface with a non-porous nickel bottom layer using a plating solution to form a non-porous nickel bottom layer; S2. electroplating an intermediate layer on the upper surface of the non-porous nickel bottom layer; S3. Electroplating the palladium-nickel coating with a plating solution on the upper surface of the intermediate layer to form a palladium-nickel coating; S4. Electroplating a gold layer on the upper surface of the palladium-nickel plated layer, coating the surface of the gold layer with a layer of lubricating oil to form a lubricating protective coating; thus obtaining a corrosion-resistant and temperature-shock-resistant composite layer.

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