A sulfur-free electroless nickel plating solution suitable for eutectic processes

Abstract

The application provides a sulfur-free electroless nickel plating solution suitable for a eutectic process, and relates to the technical field of electroless nickel plating.The sulfur-free electroless nickel plating solution suitable for the eutectic process is composed of the following raw materials in mass fraction: 8-15 parts of nickel salt, 10-20 parts of complexing agent, 0.1-0.5 parts of brightener, 8-16 parts of reducing agent, 0.1-0.5 parts of stabilizer, 0.2-0.8 parts of plating initiator and 1-3 parts of wetting agent.The amino hydroxyl pyrimidine compound used as the brightener in the application can not only stably withstand high temperature and not be easily decomposed, but also can not cause the phenomena of plating leakage and plating stop for fine high-end circuits when being added into the nickel solution like the current new generation of pyridine and triazole brighteners, and compared with the pyridine and triazole brighteners, the brightener has excellent performance for high-end products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electroless nickel plating, in particular, relates to a sulfur-free electroless nickel plating solution suitable for eutectic process. BACKGROUND

[0002] Eutectic refers to the phenomenon that two or more components solidify into a solid phase at a specific ratio. For example, gold and tin (Au-Sn) form a uniform mechanical mixture at the eutectic temperature (about 280℃), which has high thermal conductivity, low melting point and high shear strength. Eutectic process is to melt different materials to form a uniform alloy structure through eutectic reaction, which is used in electronic, optical, aerospace and other fields. In the eutectic process, electroless nickel plating is mainly used for pretreatment of the surface of the substrate to form a metal layer with high adhesion and corrosion resistance to optimize the eutectic welding effect.

[0003] However, in the eutectic process, the stability of the electroless nickel plating solution and the quality of the plated layer directly affect the reliability and performance of the eutectic welding. At present, the existing technology has the following shortcomings:

[0004] First, the stability of the plating solution, the plating solution decomposes itself, the main reason is that the pH value is too high or the local temperature is too high, the chemical energy level of the plating solution is increased, the multi-phase reaction is accelerated, the plating solution is decomposed internally, the color of the plating solution becomes light, foam and black particles are generated, the plated layer is rough or has pinholes, thereby affecting the adhesion of the plated layer, the eutectic interface is easy to form voids or cracks, and the high temperature stability is reduced.

[0005] Second, the quality of the plated layer mainly includes insufficient adhesion, pinholes and bubbles, uneven thickness, incomplete removal of oil stains, oxides or catalyst residues (such as palladium colloid not completely activated) on the surface of the substrate, resulting in poor adhesion of the plated layer to the substrate (<100MPa), easy delamination after eutectic welding, pinholes and bubbles leading to the formation of micropores on the surface of the plated layer, reducing the wettability of the eutectic solder, poor penetration of the plating solution for complex shaped substrates (such as blind holes, deep cavities), resulting in local thinning or missing plating of the plated layer, affecting the uniformity of the eutectic interface; in addition, the wear resistance and heat resistance of the plated layer also increase the requirements for the electroless nickel plating solution in the eutectic process.

[0006] In view of the problems in the related art, no effective solution has been proposed so far. SUMMARY

[0007] Therefore, the present application provides a sulfur-free electroless nickel plating solution suitable for eutectic process to solve the above-mentioned problems.

[0008] In order to solve the above problems, the specific technical scheme adopted by the present application is as follows:

[0009] A sulfur-free electroless nickel plating solution suitable for eutectic process, the sulfur-free electroless nickel plating solution suitable for eutectic process is composed of the following raw materials in mass fraction:

[0010] Nickel salt 8-15 parts, complexing agent 10-20 parts, brightener 0.1-0.5 parts, reducing agent 8-16 parts, stabilizer 0.1-0.5 parts, plating initiator 0.2-0.8 parts and wetting agent 1-3 parts.

[0011] Preferably, the nickel salt is nickel sulfate.

[0012] Preferably, the complexing agent is malic acid.

[0013] Preferably, the brightener is an amino-hydroxy pyrimidine compound, and the amino-hydroxy pyrimidine compound is 4-amino-6-hydroxy pyrimidine.

[0014] Preferably, the reducing agent is sodium hypophosphite.

[0015] Preferably, the stabilizer is a cycloalkyl pyrazole carboxylic acid compound, and the cycloalkyl pyrazole carboxylic acid compound includes 3-cyclopropyl pyrazole-5-carboxylic acid.

[0016] Preferably, the plating initiator is a composition of amino-hydroxy alkyl pteridine compound, and the composition of amino-hydroxy alkyl pteridine compound includes 2,4-diamino-6-hydroxymethyl pteridine.

[0017] Preferably, the wetting agent is a bicycloalkyl carboxylic acid compound.

[0018] Preferably, the temperature operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 70-80 DEG C.

[0019] Preferably, the pH value operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 5.5-6.5.

[0020] The beneficial effects of the present application are:

[0021] 1. The brightener in the present application adopts amino-hydroxy pyrimidine compound, which can not only stably withstand high temperature and is not easy to decompose, but also can not cause plating leakage or even stop plating phenomenon for fine high-end circuit when added into the nickel solution, compared with the current new generation such as pyridine and triazole brightener.

[0022] 2. The plating initiator in the present application adopts amino-hydroxy alkyl pteridine compound, which has good stability, and in the current electroless nickel plating, the plating initiator is a sulfur-containing compound, which has strong decomposition ability, and as the use cycle increases to 4MTO, the decomposition products increase to a certain extent, which will cause the problem of blackening of the plating layer, therefore, the plating initiator can alleviate this problem and can realize 6MTO.

[0023] 3、The stabilizer used in the present application is a cycloalkyl pyrazole carboxylic acid compound, which can not only improve the stability of traditional lead and cadmium elements, but also replace the stabilizers such as benzotriazole or sodium thiosulfate, and solve the problem of insufficient use period.

[0024] 4、The wetting agent used in the present application is a bicycloalkyl carboxylic acid compound, which can improve the uniformity of the plating layer, and excellent bonding force can be achieved for products with different regular shapes. DETAILED DESCRIPTION

[0025] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0026] According to an embodiment of the present application, a sulfur-free electroless nickel plating solution suitable for eutectic process is provided.

[0027] The sulfur-free electroless nickel plating solution suitable for eutectic process according to the embodiments of the present application is composed of the following raw materials in mass fraction:

[0028] Nickel salt 8-15 parts, complexing agent 10-20 parts, brightener 0.1-0.5 parts, reducing agent 8-16 parts, stabilizer 0.1-0.5 parts, plating initiator 0.2-0.8 parts, and wetting agent 1-3 parts.

[0029] Specifically, the present application can achieve excellent eutectic process electroless nickel plating, which has excellent stability, uniform brightness, excellent bonding force, excellent wear resistance and corrosion resistance, and the like.

[0030] As a preferred embodiment, the nickel salt is nickel sulfate.

[0031] As a preferred embodiment, the complexing agent is malic acid.

[0032] As a preferred embodiment, the brightener is an aminohydroxy pyrimidine compound, and the aminohydroxy pyrimidine compound is 4-amino-6-hydroxy pyrimidine.

[0033] The brightener is an amino-hydroxy pyrimidine compound, which can stably withstand high temperature and is not easy to decompose. Compared with the current new generation of brighteners such as pyridine and triazole, the brightener can prevent the fine high-end circuit from being plated and even stopped from being plated, and has excellent performance for high-end products.

[0034] As a preferred embodiment, the reducing agent is sodium hypophosphite.

[0035] As a preferred embodiment, the stabilizer is a cycloalkyl pyrazole carboxylic acid compound, which includes 3-cyclopropyl pyrazole-5-carboxylic acid.

[0036] The stabilizer is a cycloalkyl pyrazole carboxylic acid compound, which has good stability and can prevent high-end products from being plated and even stopped from being plated, compared with heterocyclic amino acid ester compounds and lead and cadmium compounds.

[0037] As a preferred embodiment, the plating initiator is an amino-hydroxy alkyl pteridine compound composition, which includes 2,4-diamino-6-hydroxymethyl pteridine.

[0038] The plating initiator is an amino-hydroxy alkyl pteridine compound, which has good stability. In the current electroless nickel plating, the plating initiator is a sulfur compound, which has strong decomposition ability. When the use period reaches 4MTO (MTO: metal exchange period, which refers to the content of metal from the start of the cylinder, when the total amount of metal added to the plating solution is equal to the amount of metal in the cylinder at the start, a MTO period is completed), the decomposition products accumulate to a certain extent, which can cause the plating layer to become black. Therefore, the plating initiator can alleviate this problem and achieve 6MTO.

[0039] As a preferred embodiment, the wetting agent is a bicycloalkyl carboxylic acid compound.

[0040] The wetting agent is a bicycloalkyl carboxylic acid compound, which can improve the uniformity of the plating layer and achieve excellent adhesion for products with different regular shapes.

[0041] As a preferred embodiment, the temperature operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 70-80°C.

[0042] As a preferred embodiment, the pH value operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 5.5-6.5.

[0043] The specific implementation of the present application is further described in detail in combination with examples and comparative examples: Example 1

[0044] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with mass concentration: nickel sulfate 11 g / L, malic acid 15 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 2,4-diamino-6-hydroxymethyl-pteridine 0.5 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0045] The temperature operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 75℃, the pH value operating condition is 6, and the operating time is 25 min.

[0046] Among them, the test results of example 1 are: the binding force is excellent; the uniformity is excellent; the stability is excellent; and the penetration plating phenomenon is excellent. Example 2

[0047] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with mass concentration: nickel sulfate 11 g / L, malic acid 15 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 2,4-diamino-6-hydroxymethyl-pteridine 0.5 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0048] The temperature operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 75℃, the pH value operating condition is 6, and the operating time is 25 min.

[0049] Among them, the test results of example 2 are: the binding force is excellent; the uniformity is excellent; the stability is excellent; and the penetration plating phenomenon is excellent. Example 3

[0050] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with mass concentration: nickel sulfate 11 g / L, malic acid 15 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 2,4-diamino-6-hydroxymethyl-pteridine 0.5 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0051] The temperature operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 75℃, the pH value operating condition is 6, and the operating time is 25 min.

[0052] Among them, the test results of example 3 are: the binding force is excellent; the uniformity is excellent; the stability is excellent; and the penetration plating phenomenon is excellent.

[0053] Comparative example 1

[0054] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with the following mass concentrations: nickel sulfate 11 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 2,4-diamino-6-hydroxymethylpteridine 0.5 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0055] In the comparison example 1, the complexing agent is absent compared with the example 1, and the test results are as follows: the binding force is poor; the uniformity is poor; the stability is poor; and the penetration phenomenon is poor.

[0056] Comparison Example 2

[0057] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with the following mass concentrations: nickel sulfate 11 g / L, malic acid 15 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 2,4-diamino-6-hydroxymethylpteridine 0.5 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0058] In the comparison example 2, the brightener is absent compared with the example 1, and the test results are as follows: the binding force is excellent; the uniformity is good; the stability is excellent; and the penetration phenomenon is good.

[0059] Comparison Example 3

[0060] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with the following mass concentrations: nickel sulfate 11 g / L, malic acid 15 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 2,4-diamino-6-hydroxymethylpteridine 0.5 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0061] In the comparison example 3, the stabilizer is absent compared with the example 1, and the test results are as follows: the binding force is good; the uniformity is good; the stability is relatively poor; and the penetration phenomenon is good.

[0062] Comparison Example 4

[0063] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with the following mass concentrations: nickel sulfate 11 g / L, malic acid 15 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 3-exo-bicyclo[2.2.1]heptane-2-exo-carboxylic acid 2 g / L;

[0064] In which, the comparative example 4 lacks a plating initiator compared with the example 1, and the test results are as follows: the bonding force is excellent; the uniformity is poor; the stability is excellent; and the penetration plating phenomenon is excellent.

[0065] Comparative example 5

[0066] The sulfur-free electroless nickel plating solution suitable for eutectic process provided in the example comprises the following components with mass concentration: nickel sulfate 11 g / L, malic acid 15 g / L, 4-amino-6-hydroxy pyrimidine 0.3 g / L, sodium hypophosphite 12 g / L, 3-cyclopropyl pyrazole-5-carboxylic acid 0.3 g / L, 2,4-diamino-6-hydroxymethylpteridine 0.5 g / L;

[0067] In which, the comparative example 5 lacks a wetting agent compared with the example 1, and the test results are as follows: the bonding force is excellent; the uniformity is good; the stability is excellent; and the penetration plating phenomenon is excellent.

[0068] In addition, the evaluation criteria for the results of the examples and comparative examples in the application are shown in Table 1.

[0069]

[0070] In summary, by means of the technical solutions of the application, the brightener in the application adopts amino hydroxy pyrimidine compounds, which can not only stably withstand high temperature and not easily decompose, but also, like the current new generation of pyridine and triazole brighteners, can cause plating leakage or even plating stop for fine high-end circuits when added to the nickel solution. In comparison, the brightener has excellent performance for high-end products. The plating initiator in the application adopts amino hydroxy alkyl pteridine compounds, which have good stability. At present, in electroless nickel plating, the plating initiator is a sulfur compound, which has strong decomposition ability. Moreover, as the use period increases to 4MTO, the accumulation of the decomposition products will increase to a certain extent, which will cause the plating layer to turn black. Therefore, the plating initiator can alleviate this problem and can be used for 6MTO. The cycloalkyl pyrazole carboxylic acid compound used in the application can not only improve the stability of traditional lead and cadmium elements, but also replace the use period of the stabilizer such as benzotriazole or sodium thiosulfate. The wetting agent used in the application is a bicycloalkyl carboxylic acid compound, which can improve the uniformity of the plating layer and achieve excellent bonding force for products with different regular shapes.

[0071] Those skilled in the art will understand that the embodiments of the application can be provided as methods, systems or computer program products. Therefore, the application can be in the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to magnetic disk storage, optical storage, etc.) containing computer usable program code.

[0072] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A sulfur-free electroless nickel plating solution suitable for eutectic processes, characterized in that, The sulfur-free electroless nickel plating solution suitable for eutectic process is composed of the following raw materials in mass fraction: 8-15 parts of nickel salt, 10-20 parts of complexing agent, 0.1-0.5 parts of brightener, 8-16 parts of reducing agent, 0.1-0.5 parts of stabilizer, 0.2-0.8 parts of plating initiator and 1-3 parts of wetting agent; The brightener is an amino-hydroxy pyrimidine compound, and the amino-hydroxy pyrimidine compound is 4-amino-6-hydroxy pyrimidine; The stabilizer is a cycloalkyl pyrazole carboxylic acid compound, and the cycloalkyl pyrazole carboxylic acid compound includes 3-cyclopropyl pyrazole-5-carboxylic acid; The plating initiator is a composition of amino-hydroxy alkyl pteridine compound, and the composition of amino-hydroxy alkyl pteridine compound includes 2,4-diamino-6-hydroxymethyl pteridine; The wetting agent is a bicycloalkyl carboxylic acid compound.

2. The sulfur-free electroless nickel plating solution suitable for eutectic process according to claim 1, wherein, The nickel salt is nickel sulfate.

3. The sulfur-free electroless nickel plating solution suitable for eutectic process according to claim 1, wherein, The complexing agent is malic acid.

4. The sulfur-free electroless nickel plating solution suitable for eutectic process according to claim 1, wherein, The reducing agent is sodium hypophosphite.

5. The sulfur-free electroless nickel plating solution suitable for eutectic process according to claim 1, wherein, The temperature operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 70-80℃.

6. The sulphur-free electroless nickel plating bath according to claim 5, wherein The pH value operating condition of the sulfur-free electroless nickel plating solution suitable for eutectic process is 5.5-6.5.

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