CN117779129A

CN117779129A - Electronic electroplating rhodium alloy solution, preparation method and electroplating method

Info

Publication number: CN117779129A
Application number: CN202311817790.8A
Authority: CN
Inventors: 门松明珠; 周爱和
Original assignee: Kunshan A Tripod Plating Equipment Co ltd
Current assignee: Kunshan A Tripod Plating Equipment Co ltd
Priority date: 2023-12-27
Filing date: 2023-12-27
Publication date: 2024-03-29

Abstract

The invention relates to the technical field of electronic plating, and discloses an electronic plating rhodium alloy solution, a preparation method and a plating method. The electro-plating rhodium alloy solution comprises: rhodium compound 9.72-87.5 mmol/L, stabilizer 5.67-57.5 mmol/L, phosphorous acid 65-1400 mmol/L, metallic nickel salt 0.55-8.5 mmol/L and additive 0.37-1.5 mmol/L. According to the rhodium alloy solution electronic plating process, the rhodium nickel phosphorus alloy plating layer subjected to electrolytic precipitation has a compact amorphous structure, and has high uniformity of plating layer distribution, high corrosion resistance and excellent friction resistance; further, when the forward and backward pulse electrolysis power supply is adopted, the surface electrolysis electronic product with uniform plating layers attached with through holes, blind hole inner walls and micro precise inner walls in various shapes can be effectively provided, and the surface electrolysis electronic product is used for meeting the requirements of high-tech, high-quality and high-precision electronic electroplating product fields and development trend of high-end precise rhodium alloy materials.

Description

Electronic electroplating rhodium alloy solution, preparation method and electroplating method

Technical Field

The invention relates to the technical field of electronic plating, in particular to an electronic plating rhodium alloy solution, a preparation method and a plating method.

Background

The metal plating layer is formed on the plating piece by the electronic plating rhodium alloy solution through the cathode electrolytic precipitation principle, and the method is a special manufacturing technology for nano precision manufacturing of electronic components, and the application fields comprise wafer chip electroplating, printed board electroplating, lead frame electroplating, connector electroplating, microwave device and other electronic component manufacturing. The method is the only key technology capable of realizing nanoscale electronic logic interconnection and micro-nano structure manufacturing, processing and forming, and electronic plating has become the basic, universal and non-replaceable special manufacturing technology in the production of high-end electronic products such as wafer chip manufacturing, three-dimensional integration, device packaging, micro-nano device manufacturing, micro-electromechanical systems, sensors, components and the like.

In order to provide the electronic components with reliable and excellent performance, the rhodium metal plating layer formed on the surface of the plated part needs to satisfy the requirements of high-efficiency electronic plating rhodium alloy solution and electronic plating method for plated parts with complex shapes, which have high uniformity, excellent compactness and strong corrosion resistance under various severe environments.

When the electronic plating rhodium alloy solution and the electronic plating method are adopted to manufacture the precise nanoscale electronic component plating material, the cross-sectional area of the electronic component material circuit gradually increases along with the increase of the thickness of the circuit surface plating layer, and the metal cations have the characteristic of preferential discharge deposition at the edge of the plating component circuit, so that the adjacent circuit distance decreases along with the increase of the thickness of the circuit surface plating layer and tends to generate a closed short circuit, and meanwhile, the uniformity of the circuit surface plating layer decreases, so that the precision of the electronic circuit of the electronic component is reduced and even cannot meet the product specification requirement. In addition, the problem of plating fracture caused by internal stress of the rhodium plating layer is also a scientific problem and a technical difficulty that the electronic plating rhodium alloy solution and the electronic plating method of the prior art are urgently needed to be improved.

In the prior art, in order to make the rhodium plating layer satisfy high uniformity, excellent compactness, strong corrosion resistance and solve the problem of rhodium plating layer fracture, various technical solutions for solving the problem have been proposed.

Patent CN 111850631A discloses a high-gloss decorative rhodium plating electroplating solution, the brightness of the plating layer is 90+/-0.3, the performance of the rhodium plating layer is stable, the utilization rate of rhodium metal is up to 99%, and the waste of raw materials is reduced.

Patent CN 113186572A provides a rhodium-ruthenium alloy electroplating process which has simple process steps, high production efficiency and low cost and can improve the rust resistance of the product.

Patent CN 115386927A provides a rhodium-ruthenium plating method for copper surfaces, which can effectively improve the wear resistance and corrosion resistance of copper surfaces.

Patent CN 110494596A provides a rhodium plating solution for electrolysis of rhodium, which can obtain a dense amorphous plating film of rhodium and phosphorus, and is used for solving the problem of plating fracture caused by internal stress of rhodium plating.

However, none of the prior art of the above-mentioned patent has the characteristics of satisfying the high uniformity of the metal plating layer, excellent compactness, strong corrosion resistance and solving the problem of cracking of the rhodium plating layer at the same time.

Aiming at high-end precision electronic plating parts with complex shapes, such as electroplating deposition of wafers, the method has the characteristics of high uniformity, excellent compactness, strong corrosion resistance under various severe environments and solving the problem of rhodium plating fracture, and is an important technical index for production and manufacture of high-end electroplating processes, but the conventional electroplating method is difficult to achieve the electroplating effect required by the technical index. The main reasons are as follows: it is difficult to simultaneously realize high-speed and uniform flow electroplating solution which washes the surface of the chip electronic material plating piece but does not interfere with electric field distribution.

The problems are not reported in the literature on solutions; the existence of scientific problems and technical difficulties in the technical field of electroplating prevents the continuous and innovative and growing demands of aerospace, new energy automobiles and communication electronic industries on high-end electronic component materials, and is a research subject for urgent innovation and breakthrough.

Disclosure of Invention

The invention aims to solve the technical problems that: overcomes the defects in the prior art and provides an electronic plating rhodium alloy solution, a preparation method and an electroplating method. The electronic plating rhodium alloy solution is suitable for special electroplating processing of high-end precise electronic plating parts, and achieves the aim of manufacturing rhodium plating alloy products by carrying out electronic plating on the high-end precise electronic plating parts; the electroplating method is easy to operate, can simply and efficiently electroplate and manufacture high-end precise electronic devices with high uniformity, excellent compactness, strong corrosion resistance under various severe environments and complex shapes, which solve the problem of rhodium coating fracture, and can be widely applied to the electroplating field of high-end electronic products such as wafer chip manufacture, three-dimensional integration, device packaging, sensors, micro-nano device manufacture, micro-electromechanical systems, components and the like.

The technical scheme adopted for solving the technical problems is as follows:

an electro-plating rhodium alloy solution comprising the following concentrations of components:

further, the rhodium compound is selected from one or more of sodium hexachlororhodium, rhodium sulfate and rhodium phosphate.

Further, the stabilizer is selected from five-membered heterocyclic compounds with substituent R, wherein the substituent R is selected from one or more of sulfonic acid group, nitryl, amino, carboxyl, halogenated group, hydroxyl substituted alkyl, halogen substituted alkyl and alkyl with 1-4 carbon atoms; the five-membered heterocyclic compound is a five-membered ring containing one heteroatom, a five-membered ring containing two heteroatoms or a five-membered ring containing three or more heteroatoms.

Further, the five-membered ring containing one heteroatom is selected from one or more of thiazole, pyrrole and furan, and specifically comprises:

the thiazole is selected from one or more of 2-methyl-5-nitrothiazole, 2-methyl-thiazole-4-carboxylic acid, 4-methyl-5-nitrothiazole, 2-amino-5-nitrothiazole, 2-methyl-5-thiazole amine, 2-thiazole-2-ethylamine, 2-propylthiazole, 2-nitrothiazole, thiazole-4-boric acid and thiazole-2-sulfonic acid;

pyrrole is selected from one or more of 2-nitropyrrole, 3-nitropyrrole, 2-pyrrole carboxylic acid, 4-methyl-2-pyrrole carboxylic acid, 1-aminopyrrole, 2-aminopyrrole, 3-aminopyrrole, 2-methylpyrrole, 3-chloropyrrole, pyrrole-2-sulfonic acid, 1-methyl-2-pyrrole carboxylic acid and (pyrrole-3-yl) -acetic acid;

Furans are selected from one or more of 2-bromo-5-nitrofuran, 3-methylfuran, 2-nitrofuran, 5-methylfuran-2-sulfonic acid, furan-5-sulfonic acid-2-carboxylic acid, furan-2-carboxylic acid, 2- (trifluoromethyl) furan-3-carboxylic acid, 2, 5-dimethyl-3-furanoic acid, 3-furancarboxylic acid, 3-furanacetic acid and 3-furanmethanol.

Further, the five-membered ring containing two hetero atoms is selected from one or more of oxazoles, pyrazoles, thiazoles, imidazoles, isoxazoles and isothiazoles, and specifically comprises:

the oxazoles are selected from one or more of 2-amino-oxazoles, oxazole-4-carboxylic acid, oxazole-5-methanol, 5-oxazolecarboxylic acid, (2-methyl-1, 3-oxazol-5-yl) methanol, 2,4, 5-trimethyl-oxazoles, 3-methyl isoxazol-4-amine, oxazole-5-acetic acid, 2-bromo-5-carboxylic acid, 2-bromo-4-oxazolecanol, 4, 5-dimethyl oxazole, (2-chloro-4-oxazolecanol), oxazole-4-methylamine, 4-methyl oxazole-5-carboxylic acid, 2-amino-1, 3-oxazole-4-carboxylic acid, 2-ethyl-1, 3-oxazole-4-carboxylic acid;

pyrazoles are selected from one or more of 1H-pyrazole-3-carboxylic acid, 3-methyl-1H-pyrazole-5-carboxylic acid, 3, 5-pyrazole dicarboxylic acid, 3-methyl-5-trifluoromethyl-1H-pyrazole, 3, 5-dimethyl-4-iodopyrazole, 5-hydroxy-1-methyl-3-trifluoromethyl-1H-pyrazole, 4-fluoro-3-methyl-1H-pyrazol-5-ol, 3-aminopyrazole, 1, 4-dimethylpyrazole, 4-methyl-3-nitropyrazole, 1H-pyrazole-4-carboxylic acid, 1H-pyrazole-4-methanol, 3-bromo-4-methylpyrazole, 5-chloropyrazole-3-carboxylic acid;

The thiazole is selected from one or more of 2-propyl thiazole, 2-bromo thiazole, 4-methylthiazole, 2-nitro thiazole, 2-hydroxy thiazole, 2-aminothiazole, 2-thiazole methylamine, thiazole-5-formic acid, thiazole-2-sulfonic acid, 5-hydroxymethyl thiazole, 2-aminothiazole-4-ol, 2, 4-dimethyl thiazole, 2-aminothiazole-4-ol, 5-nitro-1, 3-thiazole, 2-chloro-5-nitro thiazole, 1- (thiazole-2-yl) thiourea, thiazole-4, 5-dicarboxylic acid and 2- (thiazole-2-yl) acetic acid;

imidazoles are selected from one or more of 2-methylimidazole, 2-methyl-5-nitroimidazole, 4-methyl-5-nitroimidazole, 1- (2-hydroxyethyl) -2-methyl-5-nitroimidazole, 2-amino-1-methylimidazole, 2-imidazole sulfonic acid, 2-methylimidazole-4-sulfonic acid, 2-methyl-5-nitroimidazole-1-ethanol, imidazole-2-methanol, 1-aminoethyl-2-methylimidazole, 1H-imidazole-2-acetic acid, imidazole-5-acetic acid, 4-nitroimidazole, 2, 4-dinitroimidazole, 2-mercaptoimidazole;

isoxazoles are selected from one or more of 3, 5-dimethylisoxazole-4-carboxylic acid, 3, 5-dimethyl-4-nitroisoxazole, 3-methyl-5-amino-4-isoxazolecarboxylic acid, 4-methylisoxazole, isoxazole-5-carboxylic acid, 4-amino-3, 5-dimethylisoxazole, 3-methylisoxazole-4-amine, 3-methylisoxazole-5-acetic acid, isoxazol-4-ylamine, N,3, 5-trimethylisoxazol-4-amine, 3-bromoisoxazole-5-methanol, isoxazol-3-ylmethylamine, 4-nitroisoxazole, 3-ethyl-5-methylisoxazole-4-carboxylic acid;

The isothiazoles are selected from one or more of isothiazole-3-carboxylic acid, 4-carboxyisothiazole, 3-ethylisothiazole-4-carboxylic acid, 3-methyl-4-nitroisothiazole, 5-bromo-3-methyl-4-nitroisothiazole, isothiazole-3-ylmethanol, 3-methyl-4-nitroisothiazole-5-amine, isothiazole-5-methanol, 4-nitroisothiazole, isothiazole-3-amine, 5-nitroisothiazole-3-carboxylic acid, isothiazole-5-carboxylic acid, ethyl 5-amino-3-methylisothiazole-4-carboxylic acid.

Further, the five-membered ring containing three or more hetero atoms is selected from one or more of thiadiazoles, triazoles and tetrazoles, and specifically comprises:

thiadiazoles are selected from one or more of methyl mercapto thiadiazole, 1,2, 5-thiadiazole-3-carboxylic acid, 5-chloro-1, 2, 4-thiadiazole, (1, 2, 3-thiadiazole-4-yl) methanol, 2-bromo-5-nitro-1, 3, 4-thiadiazole;

the triazole is selected from one or more of 3-bromo-4H-1, 2, 4-triazole, 3-amino-5-mercapto-1, 2, 4-triazole, 3-amino-1H-1, 2, 4-triazole-5-carboxylic acid, 3-amino-5-mercapto-1, 2, 4-triazole, 5-amino-1H-1, 2, 4-triazole-3-carboxylic acid and 4-amino-1, 2, 4-triazole;

tetrazoles are selected from one or more of 5-propyl-2H-tetrazole, 5-aminotetrazole, 2-methyl-5-amino-2H-tetrazole, methylthiotetrazole, and 1- (2-hydroxyethyl) -1H-tetrazole-5 (2H) -thione.

Further, the metal nickel salt is selected from one or more of nickel tartrate, nickel sulfate, nickel chloride, nickel nitrate, nickel sulfamate, nickel citrate, nickel carbonate, nickel bromide, nickel phosphate and nickel borate.

Further, the phosphorous acid is selected from one or more of phosphorous acid, sodium phosphite, monopotassium phosphite, potassium phosphite and ammonium hydrogen phosphite.

Further, the additive is selected from one or more of diethylenetriamine pentaacetic acid, 2-phosphonobutane-1, 2, 4-tricarboxylic acid, 3-carboxyl-3-hydroxypentanedioic acid ammonium, diethylenetriamine pentamethylene phosphonic acid, 2, 3-dihydroxysuccinic acid, 2-phosphonobutane-1, 2, 4-tricarboxylic acid sodium salt, 2-phosphonobutane-1, 2, 4-tricarboxylic acid tetrasodium salt, 2-phosphonobutane-1, 2, 4-tricarboxylic acid potassium salt, ethylenediamine tetraacetic acid, 3-carboxyl-3-hydroxypentanedioic acid, ethylenediamine tetraacetic acid triammonium, ethylenediamine tetraacetic acid potassium salt, triethylenetetramine hexaacetic acid.

Further, the current density of the electroplating rhodium alloy solution is 0.5-8.0A/dm during electroplating ² The temperature of the tank liquor is 50-60 ℃.

The preparation method of the electronic plating rhodium alloy solution specifically comprises the following steps:

adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding metal nickel salt for a small amount for multiple times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the metal nickel salt in the solution A is 0.55-8.5 mmol/L;

Step (2), a 5-liter beaker made of PP material is additionally taken, pure water with half the capacity of the beaker is added, the beaker is heated to 50 ℃, a small amount of stabilizer is added for many times under the condition of magnetic stirring, and solution B is prepared after the stabilizer is uniformly dissolved, wherein the concentration of the stabilizer in the solution B is 5.67-57.5 mmol/L;

step (3), adding phosphorous acid into the solution A prepared in the step (1) a small amount for many times, and uniformly dissolving to prepare a solution C, wherein the concentration of the phosphorous acid in the solution C is 65-1400 mmol/L;

adding rhodium compound into the solution C prepared in the step (3) for a small amount for many times, and uniformly dissolving to obtain solution D, wherein the concentration of the rhodium compound in the solution D is 9.72-87.5 mmol/L;

step (5), adding additives into the solution D prepared in the step (4) for a small amount for multiple times, and uniformly dissolving to prepare a solution E, wherein the concentration of the additives in the solution E is 0.37-1.5 mmol/L;

step (6), adding the solution B prepared in the step (2) into the solution E prepared in the step (5) a small amount for many times, and uniformly stirring and mixing to prepare a solution F;

step (7), adding the rest of pure water into the solution F prepared in the step (6) to prepare a required volume to prepare a solution G;

step (8), after the solution G prepared in the step (7) is uniformly stirred, testing the pH value of the solution G, wherein the pH value is 0.5-1.5; thus obtaining the finished product of the electronic plating rhodium alloy solution.

The electroplating method of the electronic electroplating rhodium alloy solution specifically comprises the following steps: step S1, performing alkali degreasing and acid activation treatment on a plated part; s2, performing bottom nickel plating treatment on the plated piece; s3, selecting a corresponding electronic plating rhodium alloy solution according to the plating area of the plating piece and the plating piece form, configuring a corresponding anode mask, and installing the anode mask and the plating piece in a plating device; s4, selecting a corresponding electrolytic power supply to carry out electroplating according to the plating piece; step S5, detecting the nickel concentration, rhodium concentration, phosphorous acid concentration and pH value of the solution in the electronic plating rhodium alloy solution at regular time, judging the difference from the standard value, and automatically supplementing corresponding chemical components to the insufficient part; and S6, completing the electroplating process on the plated piece.

The beneficial effects of the invention are as follows: the invention has reasonable design and has the following advantages:

(1) The experimental results of the examples and the comparative examples were combined, and it was observed that the maximum values of the plating film thicknesses of all the comparative examples were far higher than those of the examples; also, the average of the plating film thickness of all comparative examples was far higher than that of the examples; therefore, the rhodium alloy solution for electronic plating, which is used for an immersion plating method or a spraying plating solution method, has better uniform distribution performance;

(2) The electron microscope test results of the plating surface of the example adopting the plating method and the comparative example show that the prior art comparative example adopts the immersion plating mode or the plating solution plating mode, and the compactness of the plating surface is poor due to the influence of the characteristics of the plating solution; according to the electronic electroplating rhodium alloy solution, through selecting the combination of nickel and phosphorous acid, the electrolytically separated rhodium nickel phosphorus alloy coating forms an amorphous structure, so that the compactness of the surface of the coating is greatly improved, and the surface of the coating is flat and smooth;

(3) The molar ratio of the molar amount of phosphorous acid used to the total molar amount of rhodium metal and nickel metal used in the above-described examples was (6.3 to 14.6): 1, a step of; in the range, the plating layer precipitated by the immersion type and spray solution type of the electronic plating rhodium alloy solution has high uniformity, high corrosion resistance and excellent friction resistance; and solves the product missing problem of coating peeling and cracking existing in the prior rhodium plating technology;

(4) Compared with rhodium plating in the prior art, the prepared plating product has the result of a nitric acid steam test, and the corrosion resistance is far higher than that of the plating method in the prior art; from the corrosion state of the test sample after the nitric acid vapor test, pinhole-shaped corrosions ooze out from the surface of the sample of the comparative example, and corrosion of a coating crack area, wherein the existence of pinholes and cracks indicates that the uniformity of an electroplating film layer on the surface of a plating piece is insufficient, so that the compactness performance of a metal coating is poor; meanwhile, the surface roughness of the electroplated product in the prior art is too high, pinholes and surface cracks on the surface of the electroplated part are easy to invade the surface of an internal substrate when being attacked by nitric acid steam under the condition of nitric acid steam test, and corrosion reaction is generated between the pinholes and the surface cracks and the surface of the electroplated part and metal nickel or metal copper with poor corrosion resistance, so that the product is damaged from the inside, and the electronic product cannot meet the corrosion resistance requirement;

(5) Compared with the prior art, the electroplating method has the core technical method that the combination proportion and the total use quantity of the stabilizing agents in the rhodium plating solution are regulated, and the electroplating method not only solves the problem of uneven thickness of the electroplating film of the electroplating product, but also can coordinate and maintain the long-term stability of the rhodium plating solution, and ensures that the rhodium alloy plating layer of the plating product manufactured by continuous electroplating production has high distribution uniformity, high corrosion resistance and excellent friction resistance; and solves the technical problems of coating peeling and cracking existing in the prior rhodium plating technology. The method provides a feasible solution for solving a series of difficult problems that the uniformity of a rhodium metal coating in the electroplating industry is poor, the compactness of the coating is not up to the requirement, the corrosion resistance is low, and the rhodium coating is easy to peel and crack;

(6) The electronic plating rhodium alloy solution and the plating method of the invention can be applied to plating production and processing in various modes of immersing in the plating solution, single-piece plating products and continuously running terminal products; and can also be applied to a spray plating device, and the electrolytic machining of local areas of various precise electronic plating products provides a feasible process route.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a process flow diagram of an electroplating method for electrolessly plating rhodium alloy solutions in accordance with the present invention;

FIG. 2 is a schematic view of a plated article to be processed in example 1;

FIG. 3 is a schematic diagram of test points of five areas R, S, U, V, Z of the test piece of the plating piece of example 1;

FIG. 4 is a graph of test points of the thickness of the coating film in five areas R, S, U, V, Z of the test piece of the coated article in example 1;

FIG. 5 is a graph showing the results of the nitric acid vapor test corrosion rates of examples 1 to 8;

FIG. 6 is a graph showing the results of comparison of the Max-Min values of example 1, example 9 to example 13, and comparative examples 1 to 6;

FIG. 7 is a schematic view of the plated parts to be processed in examples 14 to 19;

FIG. 8 is a schematic diagram of test points of five areas H1, H2, O, L1, L2 of the test pieces of plating in examples 14 to 19;

FIG. 9 is a graph showing the results of comparison of the Max-Min values of examples 14 to 19 and comparative examples 7 to 12;

FIG. 10 is an electron microscope scan of example 14;

FIG. 11 is an electron microscope scan of comparative example 7;

FIG. 12 is a graph showing the results of the nitric acid vapor test corrosion rates of examples 14 to 19 and comparative examples 7 to 12;

FIG. 13 is a graph showing the results of surface roughness (Ra) tests of examples 14 to 19 and comparative examples 7 to 12;

FIG. 14 is a graph showing the results of the friction loss (mg) test of examples 14 to 19, and comparative examples 7 to 12;

fig. 15 is a graph showing the results of plating hardness tests of examples 14 to 19 and comparative examples 7 to 12.

Detailed Description

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms also include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, an electroplating method of an electronic electroplating rhodium alloy solution specifically comprises the following steps: step S1, performing alkali degreasing and acid activation treatment on a plated part; s2, performing bottom nickel plating treatment on the plated piece; s3, selecting a corresponding electronic plating rhodium alloy solution according to the plating area of the plating piece and the plating piece form, configuring a corresponding anode mask, and installing the anode mask and the plating piece in a plating device; s4, selecting a corresponding electrolytic power supply to carry out electroplating according to the plating piece; step S5, detecting the nickel concentration, rhodium concentration, phosphorous acid concentration and pH value of the solution in the electronic plating rhodium alloy solution at regular time, judging the difference from the standard value, and automatically supplementing corresponding chemical components to the insufficient part; and S6, completing the electroplating process on the plated piece.

The plating apparatus in S4 may use a single-sided plating mold or a double-sided plating mold.

And S5, the power supply is selected from one of a forward and reverse pulse power supply, a single pulse power supply or a high-frequency power supply.

The invention applies rhodium alloy solution to electronic plating processing on the basis of utilizing a precise plating die, thereby realizing the aim of manufacturing rhodium-plated nickel-phosphorus alloy products by electronic plating on high-end precise electronic plating parts. The invention is easy to operate, and can simply and efficiently manufacture high-end precise electronic devices with dense amorphous structures, rhodium nickel phosphorus alloy plating layers with high plating distribution uniformity, high corrosion resistance and excellent friction resistance by electroplating; further, when the forward and backward pulse electrolysis power supply is adopted, the surface electrolysis electronic product with uniform plating layers attached with through holes, blind hole inner walls and micro precise inner walls in various shapes can be effectively provided, and the surface electrolysis electronic product is used for meeting the requirements of high-tech, high-quality and high-precision electronic electroplating product fields and development trend of high-end precise rhodium alloy materials.

Example 1

An electrolessly plated rhodium alloy solution comprising the following solubility components:

the preparation method of the electronic plating rhodium alloy solution in the embodiment specifically comprises the following steps:

Adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding nickel sulfate for a small amount for multiple times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the nickel sulfate in the solution A is 0.55mmol/L;

step (2), a 5-liter beaker made of PP material is additionally taken, pure water with half the capacity of the beaker is added, the temperature is heated to 50 ℃, 2-bromo-5-nitro-1, 3, 4-thiadiazole is added for a small amount for many times under the condition of magnetic stirring, solution B is prepared after the solution B is uniformly dissolved, and the concentration of the 2-bromo-5-nitro-1, 3, 4-thiadiazole in the solution B is 5.67mmol/L;

step (3), adding phosphorous acid into the solution A prepared in the step (1) a small amount for many times, and uniformly dissolving to prepare a solution C, wherein the concentration of the phosphorous acid in the solution C is 65mmol/L;

adding rhodium sulfate into the solution C prepared in the step (3) a small amount for many times, and uniformly dissolving to prepare a solution D, wherein the concentration of the rhodium sulfate in the solution D is 9.72mmol/L;

step (5), adding 2-phosphonate butane-1, 2, 4-tricarboxylic acid into the solution D prepared in the step (4) for a small amount for multiple times, and uniformly dissolving to prepare a solution E, wherein the concentration of the 2-phosphonate butane-1, 2, 4-tricarboxylic acid in the solution E is 0.37mmol/L;

step (8), after the solution G prepared in the step (7) is uniformly stirred, testing the pH value of the solution G, wherein the pH value control target is 1.0; and according to the pH value test result, adjusting the pH value to be higher than 1.0 by using sulfuric acid solution, otherwise adjusting the pH value to be 1.0 by using sodium hydroxide solution, and obtaining the finished product of the electronic plating rhodium alloy solution.

The experimental piece of the plated part to be processed in the embodiment is shown in fig. 2, the size of the copper material is 66mm multiplied by 66mm, and the thickness is 0.35mm; single-sided electroplating, wherein the other side is protected by a special 3M electroplating adhesive tape, the peripheral edges of the electroplated side are also protected by the same 3M adhesive tape, the actual electroplating area is 60X 60mm, and the electroplating surface area is 3600mm ² 。

In this embodiment, the plating is performed by immersing the plated article in the plating solution, and the plated article having a large surface area is usually plated by using the plating method, and a positive and negative pulse electrolysis power supply is used.

Fig. 3 is a schematic diagram of five regions R, S, U, V, Z of the plating experimental piece in this embodiment. In the figure, edge S region, points 1 (7 mm ), 2 (7, 13), 3 (13, 13), 4 (7, 13), 5 (10, 10); edge R region, 1 (7 mm,59 mm), 2 (7, 52), 3 (14, 52), 4 (14, 59), 5 (10, 56); edge U region, 1 (59 mm ), 2 (59, 52), 3 (52, 52), 4 (52, 59), 5 (56, 56); edge V region, 1 (59 mm,7 mm), 2 (59, 14), 3 (52, 14), 4 (52,7), 5 (56, 10); the center Z area of the plating is 1 (30 mm,36 mm), 2 (30, 30), 3 (36, 30), 4 (36, 36), 5 (33, 33).

The rhodium alloy solution for electronic plating prepared in this example had a current density of 0.5A/dm during plating ² The bath solution temperature is 50 ℃, the electrolysis power supply adopts a forward and reverse pulse power supply, the plating part is electroplated for 137 seconds, and the thickness target of the rhodium-nickel-phosphorus alloy plating layer of the experimental piece of the plating part is set to be 800nm.

The plating conditions of example 1 are listed in table 1.

TABLE 1 example 1 electroplating conditions

	Plating conditions
		Current (ampere A)/current density (A/dm) ² )	0.18/0.5
Plating time (sec)	137
		Solution temperature T (. Degree. C.)	50
pH value of solution	1.0
		Area S (mm) of plated part ² )	3600 (Single-sided)
Rhodium nickel phosphorus alloy film thickness H (nm)	Standard of more than or equal to 800

The abscissa and the ordinate are re-identified according to the test points of the five areas R, S, U, V and Z of the plated test piece shown in fig. 3, and the coordinate identification result is shown in fig. 4. Rhodium alloy film thickness data for each test point of FIG. 4 were tested and the results of the rhodium alloy film thickness test are shown in Table 2.

TABLE 2 test results (nm) of rhodium alloy film thickness at each test point of test piece of plated item

Examples 2 to 8

In order to investigate the optimal range of the amount of phosphorous acid used in the rhodium-plated alloy solution, examples 2 to 8 differ from example 1 in that: the phosphorous acid concentration varied from 25 to 170 mmol/L. Examples 2 to 8 were identical to example 1 in other components, formulation methods and plating conditions.

Other components and experimental conditions are the same as those of example 1 except that the concentration of phosphorous acid varies within the range of 25 to 170mmol/L, and examples 2 to 8 are obtained according to the difference in the amount of phosphorous acid used, and the amounts of phosphorous acid used in each example are shown in Table 3.

TABLE 3 conditions for the test of the amount of phosphorous acid used (mmol/L)

Examples	2	3	1	4	5	6	7	8
									Phosphorous acid	25	50	65	80	120	150	160	170

The plated article samples prepared in examples 1 to 8 were subjected to appearance and various test tests, respectively.

Appearance was examined using a 40-fold optical microscope and further observed using an electron microscope at 5000-fold magnification, and the results are shown in Table 4.

TABLE 4 appearance inspection results

Examples

2

3

1

4

5

6

7

8

Microscope

Good grade (good)

Excellent (excellent)

Good grade (good)

Electron microscope

In (a)

Good grade (good)

Excellent (excellent)

Good grade (good)

In (a)

After 2 hours of the nitric acid vapor test, the etching area was examined for the ratio of the entire plating area after washing with pure water and drying, and the results are shown in Table 5, and a graph is drawn in FIG. 5.

Table 5 results of examination of corrosion rate (%) in nitric acid vapor test

Examples	2	3	1	4	5	6	7	8
									Corrosion rate (%)	3.52	2.37	0.01	0.00	0.00	0.01	0.63	1.98

The results are shown by integrating the data and the graph curves shown in Table 4, table 5 and FIG. 5, and the phosphorous acid amounts of example 1, example 4, example 5 and example 6 are in the optimum ranges, that is, the phosphorous acid amount is 65 to 1400mmol/L; the corrosion rate of nitric acid vapor is very high and serious which is lower than 65mmol/L, which indicates that the formed rhodium alloy plating layer has poor compactness, and small similar pinhole-shaped areas are observed by an electron microscope, and gaps between similar pinholes or lattices are easy to be invaded by nitric acid vapor, so that the corrosion of substrate metal is caused; when the amount of phosphorous acid used is more than 1400mmol/L, irregular bar-shaped areas are observed under an electron microscope, resulting in poor coating densification, and corrosion of the earth metal caused by intrusion of nitric acid vapor is easy.

In examples 1 to 8, the total amount of rhodium metal and nickel metal used was 10.27mmol/L; according to the screening experimental conditions result, the optimal use range of phosphorous acid 65 ~ 150mmol/L, so, phosphorous acid using molar quantity and metal total using molar quantity optimal ratio is 6.3 ~ 14.6 times.

The molar ratio of the phosphorous acid used to the total molar amount of metal (rhodium metal and nickel metal) was 6.3 to 14.6 times as large as the molar ratio of the components of example 1 and examples 9 to 13, and the amount of phosphorous acid used was calculated from the total molar amounts of rhodium compound and nickel salt of examples 1 and examples 9 to 13, and all the data are shown in Table 6.

TABLE 6 amount of phosphorous acid used (mmol/L) in example 1, example 9 to example 13

Examples	1	9	10	11	12	13
							Phosphorous acid/metal stoichiometry	6.3	7.9	9.5	11.2	12.8	14.6
Phosphorous acids	65	133	414	715	1024	1400

Example 9

adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding nickel sulfamate for a small amount for many times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the nickel sulfamate in the solution A is 1.28mmol/L;

Step (2), a 5-liter beaker made of PP material is additionally taken, pure water with half of the capacity of the beaker is added, the beaker is heated to 50 ℃, 2-methyl 5-nitrothiazole and 5-methylfuran-2-sulfonic acid are added for a small amount for many times under the condition of magnetic stirring, solution B is prepared after the solution B is uniformly dissolved, the concentration of the 2-methyl 5-nitrothiazole in the solution B is 7.32mmol/L, the concentration of the 5-methylfuran-2-sulfonic acid in the solution B is 8.35mmol/L, and the total concentration of the stabilizer mixture in the solution B is 15.67mmol/L;

adding sodium phosphite into the solution A prepared in the step (1) for a small amount for many times, and uniformly dissolving to prepare a solution C, wherein the concentration of the sodium phosphite in the solution C is 133mmol/L;

adding rhodium phosphate into the solution C prepared in the step (3) a small amount for many times, and uniformly dissolving to prepare a solution D, wherein the concentration of rhodium phosphate in the solution D is 15.57mmol/L;

adding 3-carboxyl-3-hydroxyglutarate and diethylenetriamine pentamethylene phosphonic acid into the solution D prepared in the step (4) a small amount for multiple times, and uniformly dissolving to obtain a solution E, wherein the concentration of the 3-carboxyl-3-hydroxyglutarate in the solution E is 0.32mmol/L, the concentration of the diethylenetriamine pentamethylene phosphonic acid in the solution E is 0.23mmol/L, and the total concentration of an additive mixture in the solution E is 0.55mmol/L;

step (8), after the solution G prepared in the step (7) is uniformly stirred, testing the pH value of the solution G, wherein the pH value control target is 0.5; and according to the pH test result, adjusting the pH to be higher than 0.5 by using sulfuric acid solution, otherwise adjusting the pH to be 0.5 by using sodium hydroxide solution, and obtaining the finished product of the electronic plating rhodium alloy solution.

Example 10

adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding nickel tartrate for a small amount for multiple times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the nickel tartrate in the solution A is 3.86mmol/L;

step (2), adding pure water with a volume of half of that of a beaker into a 5-liter beaker made of PP material, heating to 50 ℃, adding 5-chloropyrazole-3-carboxylic acid and (2-methyl-1, 3-oxazol-5-yl) methanol for a small amount for many times under the condition of magnetic stirring, and uniformly dissolving to obtain a solution B, wherein the concentration of the-chloropyrazole-3-carboxylic acid in the solution B is 13.57mmol/L, the concentration of the (2-methyl-1, 3-oxazol-5-yl) methanol is 12.29mmol/L, and the total concentration of a stabilizer mixture in the solution B is 25.86mmol/L;

Adding ammonium phosphite into the solution A prepared in the step (1) a small amount for many times, and uniformly dissolving to prepare a solution C, wherein the concentration of the ammonium phosphite in the solution C is 414mmol/L;

adding rhodium phosphate into the solution C prepared in the step (3) a small amount for many times, and uniformly dissolving to prepare a solution D, wherein the concentration of rhodium phosphate in the solution D is 39.75mmol/L;

step (5), adding triethylenetetramine hexaacetic acid into the solution D prepared in the step (4) for a small amount for multiple times, and uniformly dissolving to obtain a solution E, wherein the concentration of triethylenetetramine hexaacetic acid in the solution E is 0.78mmol/L;

step (8), after the solution G prepared in the step (7) is uniformly stirred, testing the pH value of the solution G, wherein the pH value control target is 1.5; and according to the pH test result, adjusting the pH to be higher than 1.5 by using sulfuric acid solution, otherwise adjusting the pH to be 1.5 by using sodium hydroxide solution, and obtaining the finished product of the electronic plating rhodium alloy solution.

Example 11

adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding nickel citrate for a small amount for multiple times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the nickel citrate in the solution A is 5.63mmol/L;

step (2), a 5-liter beaker made of PP material is additionally taken, pure water with half of the capacity of the beaker is added, the beaker is heated to 50 ℃, thiazole-2-sulfonic acid and 2-amino-1-methylimidazole are added for a small amount of times under the condition of magnetic stirring, solution B is prepared after the solution B is uniformly dissolved, the concentration of the thiazole-2-sulfonic acid in the solution B is 19.73mmol/L, the concentration of the 2-amino-1-methylimidazole is 18.55mmol/L, and the total concentration of a stabilizer mixture in the solution B is 38.28mmol/L;

step (3), adding a small amount of potassium phosphite into the solution A prepared in the step (1) for multiple times, and uniformly dissolving to prepare a solution C, wherein the concentration of the potassium phosphite in the solution C is 715mmol/L;

adding rhodium sulfate into the solution C prepared in the step (3) a small amount for many times, and uniformly dissolving to prepare a solution D, wherein the concentration of rhodium sulfate in the solution D is 58.26mmol/L;

step (5), adding a small amount of diethylenetriamine pentaacetic acid into the solution D prepared in the step (4) for multiple times, and uniformly dissolving to prepare a solution E, wherein the concentration of diethylenetriamine pentaacetic acid in the solution E is 0.99mmol/L;

Example 12

adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding nickel sulfate for a small amount for multiple times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the nickel sulfate in the solution A is 7.21mmol/L;

step (2), adding pure water with a volume of half of that of a PP (polypropylene) beaker, heating to 50 ℃, and adding 2-bromo-5-nitro-1, 3, 4-thiadiazole and 3-methyl-4-nitroisothiazole-5-amine a small amount for multiple times under the condition of magnetic stirring to obtain a solution B, wherein the concentration of the 2-bromo-5-nitro-1, 3, 4-thiadiazole in the solution B is 23.15mmol/L, the concentration of the 3-methyl-4-nitroisothiazole-5-amine is 24.66mmol/L, and the total concentration of a stabilizer mixture in the solution B is 47.81mmol/L;

Adding ammonium phosphite into the solution A prepared in the step (1) a small amount for many times, and uniformly dissolving to prepare a solution C, wherein the concentration of the ammonium phosphite in the solution C is 1024mmol/L;

adding rhodium phosphate into the solution C prepared in the step (3) a small amount for many times, and uniformly dissolving to prepare a solution D, wherein the concentration of rhodium phosphate in the solution D is 72.83mmol/L;

step (5), adding ethylenediamine tetraacetic acid into the solution D prepared in the step (4) a small amount for multiple times, and uniformly dissolving to obtain a solution E, wherein the concentration of the ethylenediamine tetraacetic acid in the solution E is 1.23mmol/L;

Example 13

adding pure water with half the capacity of the tank into a PP material electrolytic tank, heating to 50 ℃, adding nickel phosphate for a small amount for multiple times under the running condition of a circulating pump, and uniformly dissolving to obtain a solution A, wherein the concentration of the nickel phosphate in the solution A is 8.5mmol/L;

step (2), a 5-liter beaker made of PP material is additionally taken, pure water with half the capacity of the beaker is added, the temperature is heated to 50 ℃, 1-methyl-2-pyrrole carboxylic acid and 5-methyl furan-2-sulfonic acid are added for a small amount for many times under the condition of magnetic stirring, the solution B is prepared after the 1-methyl-2-pyrrole carboxylic acid and the 5-methyl furan-2-sulfonic acid are uniformly dissolved, the concentration of the 1-methyl-2-pyrrole carboxylic acid in the solution B is 7.32mmol/L and the concentration of the 5-methyl furan-2-sulfonic acid in the solution B is 8.35mmol/L, and the total concentration of the stabilizer mixture in the solution B is 15.67mmol/L;

adding sodium phosphite into the solution A prepared in the step (1) a small amount for many times, and uniformly dissolving to prepare a solution C, wherein the concentration of the sodium phosphite in the solution C is 1400mmol/L;

adding rhodium sulfate into the solution C prepared in the step (3) a small amount for many times, and uniformly dissolving to obtain a solution D, wherein the concentration of the rhodium sulfate in the solution D is 87.5mmol/L;

step (5), adding a small amount of diethylenetriamine pentaacetic acid into the solution D prepared in the step (4) for multiple times, and uniformly dissolving to prepare a solution E, wherein the concentration of the diethylenetriamine pentaacetic acid in the solution E is 1.5mmol/L;

step (8), after the solution G prepared in the step (7) is uniformly stirred, testing the pH value of the solution G, wherein the pH value control target is 1.0; and according to the pH test result, adjusting the pH to be higher than 1.0 by using sulfuric acid solution, otherwise adjusting the pH to be 1.0 by using sodium hydroxide solution, and obtaining the finished product of the electronic plating rhodium alloy solution.

The plating conditions of example 1 and examples 9 to 13 are shown in Table 7, and the rhodium-plated alloy film thickness test and data processing method of examples 9 to 13 are exactly the same as those of example 1, and the result data are shown in Table 8.

TABLE 7 plating conditions for example 1, example 9 to example 13

Table 8 results of the test of the film thickness (nm) of rhodium-plated alloy in example 1, example 9 to example 13

	1	9	10	11	12	13
							Max	852	851	855	860	857	863
Min	805	806	804	807	803	808
							AVE.	840	839	842	845	843	845
Max-Min	47	45	51	53	54	55

As can be seen from the data in Table 8, in order to meet the requirement that the product plating specification is more than or equal to 800nm, when the minimum value Min range 803-808 nm meets the specification requirement, the distribution of the film thickness Max range 851-863 nm at the periphery edge of the plating part is higher, the Max-Min difference data is in the range of 45-55 nm, the 800nm percentage of the specification value is 5.62-6.87%, and the film thickness error is controlled to be not more than 7%.

Comparative example 1

The difference from example 1 is that: the plating conditions of comparative example 1 are shown in Table 9, except that commercial rhodium plating solutions were used instead of the electroless plating rhodium alloy solutions of the present invention, and the plating times were the same. Comparative example 1 the rhodium-plated alloy film thickness of the plating samples prepared according to the plating conditions shown in table 9 was tested, and the test data are shown in table 10.

TABLE 9 electroplating conditions for comparative example 1

	Plating conditions
		Current (ampere A)/current density (A/dm) ² )	0.18/0.5
Plating time (sec)	113
		Solution temperature T (. Degree. C.)	50
pH value of solution	1.0
		Area S (mm) of plated part ² )	3600 (Single-sided)
Rhodium nickel phosphorus alloy film thickness H (nm)	Standard of more than or equal to 800

Table 10 results of the test (nm) of the film thickness of rhodium-plated alloy of comparative example 1

As can be seen from the data in Table 10, in order to meet the requirement that the product plating specification is more than or equal to 800nm, when the minimum 803nm meets the specification requirement, the film thickness distribution of the peripheral edge of the plated part is higher, the maximum value reaches 897nm, the Max-Min difference value is 94nm, and the percentage of the occupied specification value of 800nm is 11.75%.

Comparative examples 2 to 6

Plating conditions of comparative examples 1 to 6 are shown in Table 11, and rhodium-plated alloy film thickness test results of comparative examples 1 to 6 are shown in Table 12.

Table 11 electroplating conditions of comparative examples 1 to 6

Table 12 results of the film thickness test (nm) of rhodium-plated alloys of comparative examples 1 to 6

Comparative example	1	2	3	4	5	6
							Max	897	896	901	899	900	902
Min	803	800	805	809	802	810
							AVE.	874	875	878	880	879	881
Max-Min	94	96	96	90	98	92

The results of comparing the Max-Min values of example 1, example 9 to example 13 in Table 8 with those of comparative examples 1 to 6 in Table 12 are shown in FIG. 6.

As can be seen from FIG. 6, the Max-Min curve of the comparative example is much higher than that of the example, and the error range of the comparative example is 11.25% -12.25% much higher than that of the example, which is 5.62% -6.87% compared with the product plating specification of 800 nm.

In summary, the ratio of the molar amount of phosphorous acid used to the molar amount of metal alloy used in examples 9 to 13 was (6.3 to 14.6) from example 1 of table 6: 1 range.

The above results show that the rhodium nickel phosphorus alloy plating layer obtained by electrolytic precipitation has the characteristic of uniform distribution compared with the rhodium plating layer in the prior art when the rhodium alloy plating solution is immersed in the electroplating solution.

Examples 14 to 19

The example 14 used the example 1-configured electroless rhodium alloy solution, the example 15 used the example 9-configured electroless rhodium alloy solution, the example 16 used the example 10-configured electroless rhodium alloy solution, the example 17 used the example 11-configured electroless rhodium alloy solution, the example 18 used the example 12-configured electroless rhodium alloy solution, and the example 19 used the example 13-configured electroless rhodium alloy solution.

As shown in FIG. 7, the plated articles used in examples 14 to 19 were round copper material with a diameter of 30mm and a thickness of 0.3mm, one side of which was protected with a tape dedicated for 3M plating, and after the same protection of the 5mm edge of the plated side, the remaining plated area was one side with a diameter of 20mm, and the surface area was 314mm ² 。

The five test point numbers of the five areas H1, H2, O, L1, L2 of the plated test piece in fig. 8 are identical to those of example 1; the test coordinates of the edge H1 region are points 1 (6.7 mm,23.3 mm), 2 (6.7, 20), 3 (10, 20), 4 (10, 23.3), 5 (8.3, 21.7); edge H2 region, 1 (23.3 mm ), 2 (23.3, 20), 3 (20, 20), 4 (20, 23.3), 5 (21.7 ); plating center O area, 1 (16.6 mm ), 2 (16.6, 13.3), 3 (13.3 ), 4 (13.3, 16.6), 5 (15, 15); edge L1 region, 1 (6.7 mm ), 2 (6.7, 10), 3 (10, 10), 4 (10,6.7), 5 (8.3); edge L2 region, 1 (23.3 mm,6.7 mm), 2 (23.3, 10), 3 (20, 10), 4 (20,6.7), 5 (21.7,8.3).

The electroplating adopts a spraying device, which is favorable for electroplating solution and plating in unit timeThe surface of the piece is subjected to more effective flow contact, so that the electroplating efficiency is improved. The plating apparatus is generally used under a condition that the area of the plated member is small. The plating apparatus was equipped with a high-frequency electrolytic power source, and the current in example 14 was set to 94mA, and the surface area was 314mm ² Calculated, the current density was 3.0A/dm ² The method comprises the steps of carrying out a first treatment on the surface of the The calculations of examples 15 to 19 and so on. Plating samples were prepared and film thickness data was tested according to the plating conditions of examples 14 to 19 of Table 13, and the rhodium-plated alloy film thickness data of example 14 are shown in Table 14. The rhodium-plated alloy film thickness data of examples 14 to 19 are shown in Table 15.

TABLE 13 electroplating conditions for examples 14 to 19

TABLE 14 example 14 rhodium plated alloy film thickness test data (nm)

TABLE 15 results of rhodium plated alloy film thickness test (nm) for examples 14-19

Examples	14	15	16	17	18	19
							Max	863	870	867	872	868	869
Min	807	810	808	809	810	809
							AVE.	851	857	854	858	860	856
Max-Min	56	60	59	63	58	60

As can be seen from the data in Table 17, in order to meet the requirement that the product specification is not less than 800nm, the rhodium-nickel-phosphorus alloy plating layer of the plated piece obtained by adopting the spray plating method has higher distribution of the film thickness Max range 863-872 nm at the peripheral edge of the plated piece when the minimum value Min range 807-810 nm meets the specification requirement, the difference value data of Max-Min is in the range of 56-63 nm, the percentage of the occupied specification value 800nm is 7.0-7.87%, and the film thickness error is controlled to be not more than 8%.

Comparative examples 7 to 12

The differences from examples 14 to 19 are that: commercial rhodium plating solution is used to replace the electronic rhodium plating alloy solution of the invention, and other conditions are the same except that the plating time is different.

Comparative examples 7 to 12 plating conditions are shown in table 16, and data of rhodium plated alloy film thicknesses of comparative examples 7 to 12 are shown in table 17.

TABLE 16 electroplating conditions for comparative examples 7 to 12

Table 17 comparative examples 7 to 12 rhodium plated alloy film thickness test results (nm)

The results of comparing the Max-Min values of examples 14 to 19 in Table 15 with those of comparative examples 7 to 12 in Table 17 are shown in FIG. 9.

As can be seen from FIG. 9, the Max-Min curve of the comparative example is much higher than that of the example, and the error range of the comparative example is 14.62% -16.5% much higher than that of the example by 7.0% -7.87% compared with the standard of 800nm of the product plating specification.

The above results show that the rhodium nickel phosphorus alloy plating layer obtained by electrolytic deposition in the plating solution method of the present invention has a uniform thickness distribution of the plating layer, as compared with the rhodium plating layer obtained by conventional plating, in the same manner as in the plating solution method.

The plating surfaces of example 14 and comparative example 7 were observed using an S-4800 scanning electron microscope, the results of example 14 are shown in FIG. 10, and the results of comparative example 7 are shown in FIG. 11.

As can be intuitively observed from fig. 10, the rhodium nickel phosphorus aggregate coating is flat, compact and free of metal lattice features; while the coating shown in fig. 11 is rough, has poor compactness, and can clearly observe the distribution of metal lattices.

Example 20

The plating samples prepared in examples 14 to 19 and comparative examples 7 to 12 were subjected to a nitric acid vapor test, a plating product surface roughness test, a plating product friction test, and a plating hardness test.

(1) Nitric acid steam test

The nitric acid steam test is carried out according to the national standard GB/T19351-2003/ISO 14647:2000 implementations.

Experimental time: 2 hours.

Test sample: examples 14 to 19, and comparative examples 7 to 12.

The test results are shown in% corrosion and are shown in Table 18, and a graph is shown in FIG. 12.

Table 18 test results of nitric acid vapor corrosion (%) for examples and comparative examples

Examples	Corrosion rate (%)	Comparative example	Corrosion rate (%)
				Example 14	0.002	Comparative example 7	1.71
Example 15	0.005	Comparative example 8	1.58
				Example 16	0.006	Comparative example 9	1.68
Example 17	0.003	Comparative example 10	1.83
				Example 18	0.008	Comparative example 11	1.71
Example 19	0.009	Comparative example 12	1.67

The results of the nitric acid vapor tests of examples 14 to 19 and comparative examples 7 to 12 are shown in FIG. 12. It can be observed from the graph that the rhodium nickel phosphorus alloy of the invention has stronger corrosion resistance compared with the rhodium metal plating layer in the prior art.

(2) Surface roughness test of plated product

The surface roughness test of the plated product is implemented according to the national standard GB3505-83, and the surface roughness is measured by adopting a 3D contour measuring instrument VR-6000 manufactured by Kidney.

Test sample: examples 14 to 19, and comparative examples 7 to 12.

The test results are shown in nm and are shown in Table 19 and graphically depicted in FIG. 13.

Table 19 results of surface roughness (Ra) test of examples and comparative examples

Examples	Surface roughness (Ra) (nm)	Comparative example	Surface roughness (Ra) (nm)
				Example 14	57	Comparative example 7	292
Example 15	59	Comparative example 8	297
				Example 16	53	Comparative example 9	301
Example 17	58	Comparative example 10	295
				Example 18	61	Comparative example 11	303
Example 19	55	Comparative example 12	306

The surface roughness of examples 14 to 19 and comparative examples 7 to 12 is shown in fig. 13. As can be seen from the figures, the comparison of the surface roughness of the examples and the comparative examples shows that the plating method using the electroless rhodium alloy plating solution of the present invention has a much lower range of surface roughness of the plated article than the prior art rhodium plating solution method, and thus the compactability of the plated article surface is much more advantageous.

(3) Friction test of plated article product

The sliding friction and wear test of the coating is implemented according to the national standard GB-T12444-2006, and a CSM ball friction and wear test device is adopted to test samples: examples 14 to 19, and comparative examples 7 to 12.

The test results are shown in terms of the loss amount (mg) of the weight difference before and after the friction test, and the results are shown in Table 20, and the graph is shown in FIG. 14.

Table 20 results of the friction loss (mg) test of examples and comparative examples

Examples	Friction loss (mg)	Comparative example	Friction loss (mg)
				Example 14	2.3	Comparative example 7	8.3
Example 15	2.5	Comparative example 8	8.5
				Example 16	3.1	Comparative example 9	8.2
Example 17	2.2	Comparative example 10	9.7
				Example 18	2.7	Comparative example 11	9.3
Example 19	2.1	Comparative example 12	8.8

The results of the test of the amounts of friction loss of the plating layers of examples 14 to 19 and comparative examples 7 to 12 are shown in fig. 14. As can be seen from the graph, the friction loss amount of the examples ranges from 2.1 to 3.1mg, the friction loss amount of the comparative examples ranges from 8.2 to 9.7mg, and the friction loss amount of the examples is much smaller than that of the comparative examples. Therefore, compared with the rhodium metal plating layer in the prior art, the rhodium nickel phosphorus alloy has stronger friction resistance.

(4) Hardness test of coating

Test sample: examples 14 to 19, and comparative examples 7 to 12.

The detection purpose is as follows: resistance to mechanical effects such as impact, scoring; and the compactness of the coating, the better the compactness, the higher the hardness of the coating, the poor the compactness and the reduced the hardness of the coating.

The test method comprises the following steps: and measuring the plating layer by adopting a triangular pressure head of a microhardness meter.

Performing a standard; GB/T9790-2021 microhardness test of metallic materials, metals and other inorganic coverings.

Test equipment:a durometer.

Evaluation criteria: hardness unit kg/mm ² Represented by HV.

The test results are shown in terms of coating hardness (Hv), and the results are shown in table 21, and a graph is shown in fig. 15.

Table 21 plating hardness (Hv) test results for examples and comparative examples

Examples	Hardness of plating (Hv)	Comparative example	Hardness of plating (Hv)
				Example 14	735	Comparative example 7	967
Example 15	755	Comparative example 8	982
				Example 16	746	Comparative example 9	975
Example 17	753	Comparative example 10	968
				Example 18	748	Comparative example 11	991
Implementation of the embodimentsExample 19	731	Comparative example 12	989

The plating hardness (Hv) test results of examples 14 to 19 and comparative examples 7 to 12 are shown in fig. 14. As can be seen from the graph, the plating deposited in the comparative example has a Vickers hardness as high as 900 to 1,000Hv and an extremely high internal stress, and thus has a problem that the plating is easily peeled off and plating cracks are generated. However, the rhodium alloy plating layer of the invention achieves the purpose of reducing the Vickers hardness of the rhodium plating layer by alloying nickel, phosphorus and rhodium; meanwhile, nickel enters rhodium metal lattices, so that the binding force between the nickel and a bottom nickel layer on the surface of a plated part is greatly improved, and the problems that a rhodium plating layer is easy to peel and cracks are generated in the rhodium plating layer are solved.

The rhodium nickel phosphorus alloy plating layer prepared by the electroplating method of the electronic electroplating rhodium alloy solution has better corrosion resistance by combining the test result of an electron microscope, the test result of a nitric acid steam test, the test result of the surface roughness of the plating layer and the test result of friction loss; the plating layer compactness of the electronic plating rhodium alloy solution is superior to that of the rhodium plating method in the prior art.

In summary, the beneficial effects of the invention are as follows:

(3) The molar ratio of the molar amount of phosphorous acid used to the total molar amount of rhodium metal and nickel metal used in the above examples was (6.3 to 14.6): 1; in the above range, the plating layer precipitated by immersing and spraying the rhodium alloy solution for electronic plating of the invention has high uniformity of distribution, high corrosion resistance and excellent friction resistance; and solves the product missing problem of coating peeling and cracking existing in the prior rhodium plating technology;

(6) The electronic plating rhodium alloy solution and the plating method of the invention can be applied to plating production and processing in various modes of immersing in the plating solution, single-piece plating products and continuously running terminal products; the method can also be applied to a spray plating device, and the electrolytic machining of the local area of various precise electronic plating products provides a feasible process route;

(7) The rhodium nickel phosphorus alloy plating layer provided by the electronic plating rhodium alloy solution and the plating method of the invention has the advantages that the nickel atoms occupy part of lattice positions of rhodium metal lattices, so that the formed alloy plating layer is difficult to detect that the rhodium metal lattices belong to an amorphous structure; therefore, the rhodium nickel phosphorus alloy plating layer has the inherent characteristic of an amorphous structure, has high compactness, good surface smoothness and glossiness, excellent plating layer distribution uniformity and strong corrosion resistance to various corrosive gases; the electronic electroplating rhodium alloy solution of the invention is organically combined with various precise electroplating dies, and various precise nano electroplating methods formed in an optimized way have very wide application prospects in the high-precision electronic industry and the semiconductor manufacturing industry, especially in the high-speed development of the high-precision wafer electroplating industry;

(8) The electronic rhodium plating alloy solution and the electroplating method provided by the invention provide an alternative excellent scheme of rhodium plating alloy for solving a series of problems existing in the current rhodium plating electroplating method; in addition to the performance characteristics of rhodium nickel phosphorus alloy plating layers precipitated by the various rhodium plating alloy solutions, in the rhodium plating alloy of the invention, expensive rhodium metal resources can be saved by the participation of nickel and phosphorus.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. An electronic plating rhodium alloy solution, characterized in that: comprises the following components in concentration:

rhodium compound 9.72-87.5 mmol/L

Stabilizer 5.67-57.5 mmol/L

0.55 to 8.5mmol/L of metallic nickel salt

Phosphorous acid 65-1400 mmol/L

Additives of 0.37-1.5 mmol/L.

2. An electroless rhodium-plated alloy solution according to claim 1, wherein: the rhodium compound is selected from one or more of sodium hexachlororhodium, rhodium sulfate and rhodium phosphate.

3. An electroless rhodium-plated alloy solution according to claim 1, wherein: the stabilizer is selected from five-membered heterocyclic compounds with substituent R, and the substituent R is selected from one or more of sulfonic acid group, nitryl, amino, carboxyl, halogenated group, hydroxyl substituted alkyl, halogen substituted alkyl and alkyl with 1-4 carbon atoms; the five-membered heterocyclic compound is a five-membered ring containing one heteroatom, a five-membered ring containing two heteroatoms or a five-membered ring containing three or more heteroatoms.

4. An electrotinated rhodium alloy solution according to claim 3, wherein: the five-membered ring containing one heteroatom is selected from one or more of thiazoles, pyrroles and furans;

the five-membered ring containing two hetero atoms is selected from one or more of oxazoles, pyrazoles, thiazoles, imidazoles, isoxazoles and isothiazoles;

the five-membered ring containing three or more hetero atoms is selected from one or more of thiadiazoles, triazoles and tetrazoles.

5. An electroless rhodium-plated alloy solution according to claim 1, wherein: the metal nickel salt is selected from one or more of nickel tartrate, nickel sulfate, nickel chloride, nickel nitrate, nickel sulfamate, nickel citrate, nickel carbonate, nickel bromide, nickel phosphate and nickel borate.

6. An electroless rhodium-plated alloy solution according to claim 1, wherein: the phosphorous acid is selected from one or more of phosphorous acid, sodium phosphite, monopotassium phosphite, potassium phosphite and ammonium hydrogen phosphite.

7. An electroless rhodium-plated alloy solution according to claim 1, wherein: the additive is selected from one or more of diethylenetriamine pentaacetic acid, 2-phosphonic butane-1, 2, 4-tricarboxylic acid, 3-carboxyl-3-hydroxyglutarate ammonium, diethylenetriamine pentamethylene phosphonic acid, 2, 3-dihydroxysuccinic acid, 2-phosphonic butane-1, 2, 4-tricarboxylic acid sodium salt, 2-phosphonic butane-1, 2, 4-tricarboxylic acid tetrasodium salt, 2-phosphonobutane-1, 2, 4-tricarboxylic acid potassium salt, ethylenediamine tetraacetic acid, 3-carboxyl-3-hydroxyglutarate, ethylenediamine tetraacetic acid triammonium, ethylenediamine tetraacetic acid potassium salt and triethylenetetramine hexaacetic acid.

8. An electroless rhodium-plated alloy solution according to claim 1, wherein: the current density of the electronic plating rhodium alloy solution is 0.5-8.0A/dm during plating ² The temperature of the tank liquor is 50-60 ℃.

9. A method of preparing an electroless rhodium plating alloy solution according to any one of claims 1 to 8, characterized in that: the method specifically comprises the following steps:

and (8) after the solution G prepared in the step (7) is uniformly stirred, testing the pH value of the solution G, wherein the pH value is 0.5-1.5, and thus obtaining the finished product of the electronic plating rhodium alloy solution.

10. A method of electroplating an electrolessly plated rhodium alloy solution according to any one of claims 1 to 8, wherein: the method specifically comprises the following steps:

step S1, performing alkali degreasing and acid activation treatment on a plated part;

s2, performing bottom nickel plating treatment on the plated piece;

s3, selecting a corresponding electronic plating rhodium alloy solution according to the plating area of the plating piece and the plating piece form, configuring a corresponding anode mask, and installing the anode mask and the plating piece in a plating device;

step S4, detecting the nickel concentration, rhodium concentration, phosphorous acid concentration and pH value of the solution in the electronic plating rhodium alloy solution at regular time, judging the difference from the standard value, and automatically supplementing corresponding chemical components to the insufficient part;

And S6, completing the electroplating process on the plated piece.