Cyanide-free chemical silver plating stabilizer and cyanide-free chemical silver plating solution with same

Abstract

The invention discloses a cyanide-free chemical silver plating stabilizer which comprises the following components in mass concentration: 10-20 g / L of 3-mercapto-2-butanol, 1-2 g / L of sodium thioglycolate, 0.1-0.2 g / L of ethyl thioglycolate and the balance of water. The cyanide-free chemical silver plating stabilizer provided by the invention adopts 3-mercapto-2-butanol, sodium thioglycolate and ethyl thioglycolate as raw materials, and has the characteristics that the raw materials are easy to obtain, environment-friendly, non-toxic and the like; meanwhile, 3-sulfydryl-2-butanol, sodium thioglycolate and ethyl thioglycolate all contain sulfydryl, the sulfydryl can effectively regulate and control the speed of reduction reaction of silver ions on a catalytic interface, and the stability of the cyanide-free chemical silver plating solution can be synergistically improved by compounding 3-sulfydryl-2-butanol, sodium thioglycolate and ethyl thioglycolate according to a certain proportion; and the chemical plating solution has the characteristics of low concentration, low use cost and the like, and is suitable for mass production of chemical plating.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a cyanide-free chemical silver plating stabilizer and a cyanide-free chemical silver plating solution having the stabilizer. Background Art

[0002] Cyanide-free chemical silver plating is widely used in electronic machinery, printed circuits, optics and other fields due to its excellent electrical conductivity, thermal conductivity and solderability. However, the high price of silver and poor stability of the plating solution limit the scope of application of cyanide-free chemical silver plating.

[0003] In recent years, with the advancement of chemical plating technology, cyanide-free chemical silver plating has made great progress. Adding thiourea, aminocarboxylic acid and polyamine to the plating solution can improve the stability of the plating solution and the appearance of the coating. However, it was found in the experiment that the deposition speed of the silver plating layer is still slow, the appearance is gray, and the plating solution is prone to produce white precipitation. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the main purpose of the present invention is to provide a cyanide-free chemical silver plating stabilizer and a preparation method and application thereof, aiming to solve the problems of slow deposition speed of the coating and gray appearance, and white precipitation in the plating solution.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A cyanide-free chemical silver plating stabilizer consists of 3-mercapto-2-butanol, sodium thioglycolate and ethyl mercaptoacetate.

[0007] In certain specific embodiments, the mass concentration is: 10-20 g / L 3-mercapto-2-butanol, 1-2 g / L sodium thioglycolate, 0.1-0.2 g / L ethyl thioglycolate, and the balance is water.

[0008] Furthermore, the mass concentration is 15 g / L of 3-mercapto-2-butanol, 1.5 g / L of sodium thioglycolate, 0.15 g / L of ethyl thioglycolate, and the balance is water.

[0009] The main purpose of the present invention is to provide a cyanide-free chemical silver plating solution, which comprises the above-mentioned cyanide-free chemical silver plating stabilizer.

[0010] In certain specific embodiments, the volume ratio of the cyanide-free chemical silver plating solution to the cyanide-free chemical silver plating stabilizer is 100:(0.5-1.5).

[0011] Furthermore, the volume ratio of the cyanide-free chemical silver plating solution to the cyanide-free chemical silver plating stabilizer is 100:1.

[0012] Furthermore, the following components are also included in terms of mass concentration: silver nitrate: 3-5 g / L, ammonium citrate: 2-5 g / L, glucose: 40-50 g / L, potassium sodium tartrate: 10-20 g / L, and polyethylene glycol: 1-2 g / L.

[0013] More preferably, the following components are further included, based on mass concentration: silver nitrate: 4 g / L, ammonium citrate: 3 g / L, glucose: 45 g / L, potassium sodium tartrate: 15 g / L, and polyethylene glycol: 1.5 g / L.

[0014] In some specific preferred embodiments, the chemical plating process of the cyanide-free chemical silver plating solution is as follows: the chemical plating temperature range is 40-50° C., the workpiece used for chemical plating is a copper piece; the stirring method during chemical plating is cathode movement, and the moving speed is 3-6 m / min.

[0015] Compared with the prior art, the present invention has at least the following advantages:

[0016] 1) The cyanide-free chemical silver plating stabilizer provided by the present invention adopts 3-mercapto-2-butanol, sodium thioglycolate and ethyl thioglycolate as raw materials, and has the characteristics of being easy to obtain, environmentally friendly and non-toxic. At the same time, since 3-mercapto-2-butanol, sodium thioglycolate and ethyl thioglycolate all contain thiol groups, the thiol groups can effectively regulate the speed of the reduction reaction of silver ions at the catalytic interface, and the three materials can be used in combination in a certain proportion to synergistically improve the stability of the cyanide-free chemical silver plating solution.

[0017] 2) The cyanide-free chemical silver plating solution provided by the present invention adopts a cyanide-free chemical silver plating stabilizer composed of 3-mercapto-2-butanol, sodium thioglycolate, and ethyl mercaptoacetate, which can significantly improve the stability of the plating solution, has the characteristics of low concentration, low use cost, etc., and is suitable for mass production of chemical plating. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below.

[0019] Figure 1 This is a macroscopic morphology of the copper coating in Embodiment 1 of the present invention;

[0020] Figure 2 This is a macroscopic morphology of the copper coating in Embodiment 2 of the present invention;

[0021] Figure 3 This is a macroscopic morphology of the copper coating in Embodiment 3 of the present invention;

[0022] Figure 4 This is a microscopic morphology of the copper coating in Embodiment 1 of the present invention;

[0023] Figure 5 This is a microscopic morphology of the copper coating in Embodiment 2 of the present invention;

[0024] Figure 6 This is a microscopic morphology of the copper coating in Embodiment 3 of the present invention;

[0025] Figure 7 This is a microscopic morphology of the copper coating in Comparative Example 1 of the present invention;

[0026] Figure 8 This is a microscopic morphology of the copper coating in Comparative Example 2 of the present invention;

[0027] Fig. 9 This is a microscopic morphology of the copper coating in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0029] When a certain amount, concentration or other value or parameter is expressed in the form of a range, a preferred range, or a preferred upper and lower numerical limit, it should be understood that it is equivalent to specifically revealing any range by combining any pair of upper range limits or preferred numerical values ​​with any lower range limit or preferred numerical value, regardless of whether the range is specifically disclosed. Unless otherwise indicated, the numerical range values ​​listed herein include the endpoints of the range, and all integers and fractions within the range.

[0030] Unless otherwise indicated, all percentages, parts, ratios, etc. herein are by weight.

[0031] The materials, methods, and examples herein are illustrative and are not to be construed as limiting unless specifically stated.

[0032] In the following examples, 3-mercapto-2-butanol was purchased from Wuhan Haorong Biotechnology Co., Ltd. and was analytically pure. Its role in the stabilizer is to maintain the appearance of the coating; sodium thioglycolate was purchased from Shanghai Yuanye Biotechnology Co., Ltd. and was analytically pure. Its role in the stabilizer is to maintain the plating speed; ethyl thioglycolate was purchased from Hubei Chengfeng Chemical Co., Ltd. and was analytically pure. Its role in the stabilizer is to prevent solution precipitation.

[0033] Example 1

[0034] This embodiment provides a method for preparing a cyanide-free chemical silver plating stabilizer, which comprises the following steps:

[0035] 1) Prepare 3-mercapto-2-butanol solution: weigh 12 g of mercaptobutanol and add it to 500 ml of deionized water, stir until a uniform solution is obtained, and set aside;

[0036] 2) Weighing sodium thioglycolate: Use an analytical balance to weigh 1.2 g of sodium thioglycolate and set aside;

[0037] 3) Weighing ethyl mercaptoacetate: Use an analytical balance to weigh 0.12 g of ethyl mercaptoacetate for later use;

[0038] 4) preparing a stabilizer: adding the sodium thioglycolate weighed in step 2) to the 3-mercapto-2-butanol solution prepared in step 1), stirring thoroughly to mix completely, then slowly adding the ethyl thioglycolate weighed in step 3), and then making the volume to 1 L with deionized water, stirring continuously to mix evenly, thereby obtaining a cyanide-free chemical silver plating stabilizer.

[0039] Performance testing:

[0040] Test method: 10 ml of the stabilizer prepared in Example 1 was added to every 1 L of cyanide-free chemical silver plating solution, and the workpiece was placed in the prepared cyanide-free chemical silver plating solution for chemical plating. After plating, the plated workpiece (copper part) was taken out, the thickness of the coating was measured, and the appearance of the coating was observed.

[0041] The cyanide-free chemical silver plating solution includes the following components by mass concentration: silver nitrate: 4 g / L, ammonium citrate: 3 g / L, glucose: 45 g / L, potassium sodium tartrate: 15 g / L, polyethylene glycol: 1.5 g / L, and the balance is water.

[0042] The process conditions of chemical plating are:

[0043]

[0044] At the same time, a cyanide-free chemical silver plating solution without the stabilizer of Example 1 was introduced, and the workpiece was plated under the same conditions. The thickness of the silver-plated layer was measured using a Fischer fluorescence thickness gauge, and the appearance of the coating was observed. The specific results were as follows:

[0045] 1) Morphology test

[0046] The present application uses a SEM scanning electron microscope to test the appearance of the cyanide-free chemical silver plating solution with and without the stabilizer added in Example 1, and the results are as shown in the figure: Figure 1 (Left) is a macroscopic morphology of a cyanide-free chemical silver plating layer without adding the stabilizer of the present invention; Figure 1 (Right) is a macroscopic morphology of a cyanide-free chemical silver-plated layer with the stabilizer of the present invention added thereto (the copper piece with the cyanide-free chemical silver-plated layer with the stabilizer of the present invention added thereto is a polished copper piece, the same below). Figure 4(Left) is a microscopic morphology of a cyanide-free chemical silver plating layer without adding the stabilizer of the present invention; Figure 4 (Right) is a microscopic morphology of a cyanide-free chemical silver plating layer with the stabilizer of the present invention added. From the figure, it can be seen that the cyanide-free chemical plating layer without the stabilizer added has a dull and matte appearance, and the surface crystals are relatively coarse.

[0047] 2) Thickness

[0048] This embodiment uses a Fischer fluorescence thickness gauge to measure the thickness of the silver-plated layer, and the result is: after 20 minutes of cyanide-free chemical silver plating under the above conditions, it is found that the thickness of the cyanide-free chemical silver plating layer with the stabilizer of the present invention added is 0.55um, and the thickness of the cyanide-free chemical silver plating layer without the stabilizer of the present invention added is 1.1um. The above embodiment further shows that the stabilizer of the present invention can significantly improve the stability of the plating solution and improve the quality of the coating.

[0049] 3) Decomposition

[0050] In the cyanide-free chemical silver plating solution without adding stabilizer, the solution is easy to become turbid and decompose.

[0051] Therefore: We can find that after adding the stabilizer, the thickness of the silver plating layer is stable, the crystals are fine and the plating solution is not easy to decompose.

[0052] Example 2

[0053] This embodiment provides a method for preparing a cyanide-free chemical silver plating stabilizer, which comprises the following steps:

[0054] 1) Prepare 3-mercapto-2-butanol solution: weigh 15 g of mercaptobutanol and add it to 500 ml of deionized water, stir until a uniform solution is obtained, and set aside;

[0055] 2) Weigh sodium thioglycolate: Use an analytical balance to weigh 1.5 g of sodium thioglycolate and set aside;

[0056] 3) Weighing ethyl mercaptoacetate: Use an analytical balance to weigh 0.15 g of ethyl mercaptoacetate and set aside;

[0057] 4) preparing a stabilizer: adding the sodium thioglycolate weighed in step 2) to the 3-mercapto-2-butanol solution prepared in step 1), stirring thoroughly to mix completely, then slowly adding the ethyl thioglycolate weighed in step 3), and then making the volume to 1 L with deionized water, stirring continuously to mix evenly, thereby obtaining a cyanide-free chemical silver plating stabilizer.

[0058] Performance testing:

[0059] Test method: 10 ml of the stabilizer prepared in Example 1 was added to every 1 L of cyanide-free chemical silver plating solution, and the workpiece was placed in the prepared cyanide-free chemical silver plating solution for chemical plating. After plating, the plated workpiece (copper part) was taken out, the thickness of the coating was measured, and the appearance of the coating was observed.

[0060] The cyanide-free chemical silver plating solution includes the following components by mass concentration: silver nitrate: 4 g / L, ammonium citrate: 3 g / L, glucose: 45 g / L, potassium sodium tartrate: 15 g / L, polyethylene glycol: 1.5 g / L, and the balance is water.

[0061] The process conditions of chemical plating are:

[0062]

[0063]

[0064] At the same time, a cyanide-free chemical silver plating solution without the stabilizer of Example 1 was introduced, and the workpiece was plated under the same conditions. The thickness of the silver-plated layer was measured using a Fischer fluorescence thickness gauge, and the appearance of the coating was observed. The specific results were as follows:

[0065] 1) Morphology test

[0066] The present application uses a SEM scanning electron microscope to test the appearance of the cyanide-free chemical silver plating solution with and without the stabilizer added in Example 1, and the results are as shown in the figure: Figure 2 (Left) is a macroscopic morphology of a cyanide-free chemical silver plating layer without adding the stabilizer of the present invention; Figure 2 (Right) is a macroscopic morphology of a cyanide-free chemical silver plating layer to which the stabilizer of the present invention is added. Figure 5 (Left) is a microscopic morphology of a cyanide-free chemical silver plating layer without adding the stabilizer of the present invention; Figure 5 (Right) is a microscopic morphology of a cyanide-free chemical silver plating layer with the stabilizer of the present invention added. From the figure, it can be seen that the cyanide-free chemical plating layer without the stabilizer added has a dull and matte appearance, and the surface crystals are relatively coarse.

[0067] This embodiment uses a Fischer fluorescence thickness gauge to measure the thickness of the silver-plated layer, and the result is: after 20 minutes of cyanide-free chemical silver plating under the above conditions, it is found that the thickness of the cyanide-free chemical silver plating layer with the stabilizer of the present invention added is 0.8um, and the thickness of the cyanide-free chemical silver plating layer without the stabilizer of the present invention added is 1.05um. The above embodiment further shows that the stabilizer of the present invention can significantly improve the stability of the plating solution and improve the quality of the coating.

[0068] 3) Decomposition

[0069] In the cyanide-free chemical silver plating solution without adding stabilizer, the solution is easy to become turbid and decompose.

[0070] Therefore: We can find that after adding the stabilizer, the thickness of the silver plating layer is stable, the crystals are fine and the plating solution is not easy to decompose.

[0071] Example 3

[0072] This embodiment provides a method for preparing a cyanide-free chemical silver plating stabilizer, which comprises the following steps:

[0073] 1) Prepare 3-mercapto-2-butanol solution: weigh 18 g of mercaptobutanol and add it to 500 ml of deionized water, stir until a uniform solution is obtained, and set aside;

[0074] 2) Weighing sodium thioglycolate: Use an analytical balance to weigh 1.8 g of sodium thioglycolate and set aside;

[0075] 3) Weighing ethyl mercaptoacetate: Use an analytical balance to weigh 0.18 g of ethyl mercaptoacetate and set aside;

[0076] 4) preparing a stabilizer: adding the sodium thioglycolate weighed in step 2) to the 3-mercapto-2-butanol solution prepared in step 1), stirring thoroughly to mix completely, then slowly adding the ethyl thioglycolate weighed in step 3), and then making the volume to 1 L with deionized water, stirring continuously to mix evenly, thereby obtaining a cyanide-free chemical silver plating stabilizer.

[0077] Performance testing:

[0078] Test method: 10 ml of the stabilizer prepared in Example 1 was added to every 1 L of cyanide-free chemical silver plating solution, and the workpiece was placed in the prepared cyanide-free chemical silver plating solution for chemical plating. After plating, the plated workpiece (copper part) was taken out, the thickness of the coating was measured, and the appearance of the coating was observed.

[0079] The cyanide-free chemical silver plating solution includes the following components by mass concentration: silver nitrate: 4 g / L, ammonium citrate: 3 g / L, glucose: 45 g / L, potassium sodium tartrate: 15 g / L, polyethylene glycol: 1.5 g / L, and the balance is water.

[0080] The process conditions of chemical plating are:

[0081]

[0082] At the same time, a cyanide-free chemical silver plating solution without the stabilizer of Example 1 was introduced, and the workpiece was plated under the same conditions. The thickness of the silver-plated layer was measured using a Fischer fluorescence thickness gauge, and the appearance of the coating was observed. The specific results were as follows:

[0083] 1) Morphology test

[0084] The present application uses a SEM scanning electron microscope to test the appearance of the cyanide-free chemical silver plating solution with and without the stabilizer added in Example 1, and the results are as shown in the figure: Figure 3 (Left) is a macroscopic morphology of a cyanide-free chemical silver plating layer without adding the stabilizer of the present invention; Figure 3 (Right) is a macroscopic morphology of a cyanide-free chemical silver plating layer to which the stabilizer of the present invention is added. Figure 6 (Left) is a microscopic morphology of a cyanide-free chemical silver plating layer without adding the stabilizer of the present invention; Figure 6 (Right) is a microscopic morphology of a cyanide-free chemical silver plating layer with the stabilizer of the present invention added. From the figure, it can be seen that the cyanide-free chemical plating layer without the stabilizer added has a dull and matte appearance, and the surface crystals are relatively coarse.

[0085] 2) Thickness

[0086] This embodiment uses a Fischer fluorescence thickness gauge to measure the thickness of the silver-plated layer, and the result is: after 20 minutes of non-cyanide chemical silver plating under the above conditions, it is found that the thickness of the non-cyanide chemical silver plating layer with the stabilizer of the present invention added is 0.55um, and the thickness of the non-cyanide chemical silver plating layer without the stabilizer of the present invention added is 0.95um. The above embodiment further shows that the stabilizer of the present invention can significantly improve the stability of the plating solution and improve the quality of the coating.

[0087] 3) Decomposition

[0088] In the cyanide-free chemical silver plating solution without adding stabilizer, the solution is easy to become turbid and decompose.

[0089] Therefore: We can find that after adding the stabilizer, the thickness of the silver plating layer is stable, the crystals are fine and the plating solution is not easy to decompose.

[0090] Comparative Example 1

[0091] This comparative example provides a cyanide-free chemical silver plating stabilizer, whose components and proportions are basically the same as those of Example 2, except that it contains only 15g / L 3-mercapto-2-butanol, and its preparation method and application are the same as those of Example 2. Figure 7 ,As can be seen from the figure, its microscopic morphology does not change significantly.

[0092] Comparative Example 2

[0093] This comparative example provides a cyanide-free chemical silver plating stabilizer, whose components and proportions are basically the same as those of Example 2, except that it contains only 1.5 g / L sodium thioglycolate, and its preparation method and application are the same as those of Example 2. Figure 8 ,As can be seen from the figure, its microscopic morphology does not change significantly.

[0094] Comparative Example 3

[0095] This comparative example provides a cyanide-free chemical silver plating stabilizer, whose components and proportions are basically the same as those in Example 2, except that it contains only 0.15 g / L ethyl mercaptoacetate, and its preparation method and application are the same as those in Example 2. Fig. 9 ,As can be seen from the figure, its microscopic morphology does not change significantly.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A cyanide-free chemical silver plating stabilizer, characterized in that, The stabilizer consists of 3-mercapto-2-butanol, sodium thioglycolate and ethyl thioglycolate.

2. The cyanide-free chemical silver plating stabilizer according to claim 1, characterized in that Calculated by mass concentration, 3-mercapto-2-butanol 10-20 g / L, sodium thioglycolate 1-2 g / L, ethyl thioglycolate 0.1-0.2 g / L, and the balance is water.

3. The cyanide-free chemical silver plating stabilizer according to claim 2, characterized in that, Calculated by mass concentration, 3-mercapto-2-butanol 15 g / L, sodium thioglycolate 1.5 g / L, ethyl thioglycolate 0.15 g / L, and the balance is water.

4. A cyanide-free chemical silver plating solution, characterized in that, The invention comprises the cyanide-free chemical silver plating stabilizer according to any one of claims 1 to 3.

5. The cyanide-free chemical silver plating solution according to claim 4, wherein The volume ratio of the cyanide-free chemical silver plating solution to the cyanide-free chemical silver plating stabilizer is 100:(0.5-1.5).

6. The cyanide-free chemical silver plating solution according to claim 5, wherein The volume ratio of the cyanide-free chemical silver plating solution to the cyanide-free chemical silver plating stabilizer is 100:

1.

7. The cyanide-free chemical silver plating solution according to claim 5 or 6, characterized in that, The composition includes the following components by mass concentration: silver nitrate: 3-5 g / L, ammonium citrate: 2-5 g / L, glucose: 40-50 g / L, potassium sodium tartrate: 10-20 g / L, polyethylene glycol: 1-2 g / L, and the balance is water.

8. The cyanide-free chemical silver plating solution according to claim 7, wherein In terms of mass concentration, the following components are also included: silver nitrate: 4 g / L, ammonium citrate: 3 g / L, glucose: 45 g / L, potassium sodium tartrate: 15 g / L, polyethylene glycol: 1.5 g / L, and the balance is water.

9. The cyanide-free chemical silver plating solution according to claim 4, wherein The chemical plating process of the cyanide-free chemical silver plating solution is as follows: the chemical plating temperature range is 40-50° C., the workpiece used for chemical plating is a copper piece; the stirring mode during chemical plating is cathode movement, and the moving speed is 3-6 m / min.

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