Brightener for palladium-cobalt alloy electroplating solution and application of brightener

Abstract

The invention belongs to the technical field of palladium-cobalt alloy electroplating, and particularly relates to a brightener for palladium-cobalt alloy electroplating liquid and application of the brightener. The adhesive comprises an aqueous solution of a component A and an aqueous solution of a component B, wherein the component A is selected from one or more of compounds shown in a molecular formula I or a molecular formula II; and the component B is selected from one or more of compounds shown in a molecular formula III. According to the technical scheme, on the premise that palladium-cobalt codeposition is not affected, the bright plating layer can be obtained, the current density range of a bright area is large, experiments show that the current density range of the bright area is 0.1 ASD to 4.5 ASD, and the plating layer is composed of fine microcrystals which are evenly distributed and is compact and smooth in surface and excellent in oxidation resistance and corrosion resistance. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of palladium-cobalt alloy electroplating, and in particular relates to a brightener for palladium-cobalt alloy electroplating solution and application thereof. Background Art

[0002] Palladium and its alloys have high hardness, stable chemical properties, good ductility and wear resistance, and are widely used in the decoration industry and the electrical and electronic fields. With the soaring price of gold, palladium and its alloys have become cost-effective gold plating alternatives, and the demand has increased year by year.

[0003] However, pure palladium coatings often have residual internal stress due to easy hydrogen permeation, which is prone to cracking and seriously affects their use. Palladium alloys have lower manufacturing costs, and the co-deposition potential is usually far away from the hydrogen evolution potential, which can obtain dense corrosion-resistant coatings. Among them, palladium-nickel alloys have been the most studied. However, nickel can cause dermatitis in some people. Since 1994, EU countries have banned the import of jewelry containing nickel or nickel alloys, and other Western countries have also taken restrictive measures. In contrast, palladium-cobalt alloys can overcome this shortcoming and show better stability.

[0004] Brightener is an additive added to the plating solution to obtain brightness. Brightener has good internal and external lubrication and surface brightness, and can improve the vividness and brightness of the masterbatch.

[0005] The prior art has disclosed a small amount of research results on palladium-cobalt brighteners suitable for different conditions. For example, JP5318375B2 mentions that unsaturated organic carboxylic acids or their salts can improve the glossiness of palladium-cobalt alloy films.

[0006] JP4790191B2 discloses an organic brightener suitable for high current density and high speed electroplating of palladium-cobalt alloy; US4911799A mentions that the commonly used brighteners for palladium alloys including palladium-cobalt alloys are organic sulfides, such as sulfones and sulfonic acids, sulfur-nitrogen compounds, such as sulfonamides, etc. However, the brighteners in the above-mentioned plating solutions only include a single component, and the palladium-cobalt alloy electroplating solution using such brighteners has the problem of limited current density range and insufficient brightness of the coating. Summary of the invention

[0007] The invention provides a brightener for palladium-cobalt alloy electroplating solution and application thereof, so as to solve the problems that the brightener currently used for palladium-cobalt alloy electroplating solution has limited current density range and insufficient brightness of the coating.

[0008] In order to solve the above technical problems, the technical solution of the present invention is: the brightener for palladium-cobalt alloy electroplating solution is an aqueous solution composed of component A and component B;

[0009] The component A is selected from one or more compounds shown in formula I or formula II;

[0010]

[0011] Among them, A 1 For -(CH 2 )n-, n=0, 1 or 2;

[0012] A 2 , A 3 , A 4 , A 5 and A 6 Each independently selected from -H, -OH, -CH 3 , -C 2 H 5 , -COOH, -CHO or -SO 3 M 2 ;

[0013] M 1 and M 2 Each independently selected from hydrogen ions or metal ions;

[0014]

[0015] Among them, B 1 , B 2 , B 3 , B 4 , B 5 , B 6 , B 7 and B 8 Each independently selected from -H, -OH, -CH 3 , -C 2 H 5 , -COOH, -CHO or -SO 3 H;

[0016] And B 1 , B 2 , B 3 , B 4 , B 5 , B 6 , B 7 and B 8 At least one substituent is -SO 3 H;

[0017] The B component is selected from one or more compounds shown in formula III;

[0018] RC≡C-R2(III)

[0019] Among them, R 1is selected from the group consisting of hydroxy, alkyl substituted by at least one hydroxy and / or amino, alkoxy substituted by at least one hydroxy, amino, amino substituted by at least one alkyl, and amino substituted by at least one hydroxy and one alkyl;

[0020] R 2 It is selected from hydrogen, alkyl, hydroxy, alkyl substituted by at least one hydroxy, and alkoxy substituted by at least one hydroxy.

[0021] Optionally, the metal ion is a sodium ion, a potassium ion, a magnesium ion or a calcium ion.

[0022] Optionally, the compound of formula I is

[0023] Optionally, the compound of formula II is

[0024] Alternatively, the compound of formula III is

[0025] Optionally, the ratio of component A and component B of the brightener for palladium-cobalt alloy electroplating solution is (100-1000):(1-10), preferably, (40-200):1, in parts by weight.

[0026] The present invention also provides a palladium-cobalt alloy electroplating solution, which comprises the above-mentioned brightener for the palladium-cobalt alloy electroplating solution.

[0027] Optionally, the palladium-cobalt alloy electroplating solution further comprises a palladium salt, a cobalt salt and a complexing agent, and the proportions of each component in parts by weight are as follows:

[0028]

[0029] Optionally, the palladium-cobalt alloy electroplating solution further comprises a palladium salt and a cobalt salt, and the proportions of each component in parts by weight are as follows:

[0030]

[0031] Optionally, the palladium salt is selected from one or more selected from palladium chloride, palladium bromide, palladium iodide, palladium sulfate, palladium nitrate, palladium hydroxide, diammine palladium dichloride, diammine palladium tetrachloride, dibromine palladium tetraammine palladium, diiodine palladium tetraammine palladium, diammine palladium sulfate, tetraammine palladium sulfate, palladium nitrite, palladium nitrate and palladium diammine oxalate;

[0032] Optionally, the cobalt salt is selected from one or more of cobalt chloride, cobalt bromide, cobalt iodide, cobalt oxide, cobalt sulfate, cobalt nitrate, cobalt carbonate, cobalt hydroxide, cobalt oxalate and cobalt acetate;

[0033] Optionally, the complexing agent is selected from one or more of formates, acetates, propionates, aminoacetates, citrates, acrylates, tartrates and malates.

[0034] The technical solution provided by the present invention can obtain a bright coating without affecting the co-deposition of palladium and cobalt, and the current density range of the bright area is large. Experiments show that the current density range of the bright area is 0.1-4.5ASD. The coating is composed of evenly distributed fine microcrystals, the surface is dense and smooth, and the oxidation resistance and corrosion resistance are excellent. DETAILED DESCRIPTION

[0035] For ease of understanding, the brightener for palladium-cobalt alloy electroplating solution and its application are described below in conjunction with embodiments. The technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0036] Unless otherwise specified, the reagents used in this example are all commercially available conventional products.

[0037] Example 1-10 Brightener for palladium-cobalt alloy electroplating solution

[0038] In this embodiment, the method for preparing 100 mL of the brightener for palladium-cobalt alloy electroplating solution is as follows:

[0039] 1) Weigh the required component A and component B according to the ratio;

[0040] 2) Dissolve component A and component B separately with deionized water and stir until clear;

[0041] The two solutions were mixed and the volume was adjusted to 100 mL to obtain the prepared brightener, which could be added according to the corresponding working concentration when used.

[0042] Table 1 shows the selection of components and specific usage of the brightener for 100 mL of palladium-cobalt alloy electroplating solution in Examples 1-10

[0043] Table 1

[0044]

[0045]

[0046] Example 11-20 Preparation of electroplating solution

[0047] In this embodiment, the method for preparing 1L of electroplating solution is as follows:

[0048] 1) Weigh the required palladium salt, cobalt salt and complexing agent according to the ratio;

[0049] 2) Dissolve in deionized water and stir until clear;

[0050] 3) Add a weighed amount of a brightener for palladium-cobalt alloy electroplating solution prepared according to a ratio, and adjust the volume to 1 L to obtain a plating solution.

[0051] Table 2 shows the selection of components and specific usage amounts for preparing 1L of electroplating solution in Examples 11-20.

[0052] Table 2

[0053]

[0054]

[0055] Comparative Examples 1-5 Comparative Experimental Brightener

[0056] The difference between Comparative Examples 1-5 and the embodiment lies in the composition of ingredients, and the preparation method remains unchanged. Table 3 shows the types of components of Comparative Examples 1-5 and the amount of brightener used to prepare 100 ml.

[0057] Table 3

[0058]

[0059] Comparative Examples 6-10 Comparative Experimental Plating Solutions

[0060] The difference between Comparative Examples 6-10 and Example 11 lies in the composition of ingredients, and the preparation method remains unchanged. Table 4 shows the types of components of Comparative Examples 6-10 and the amount of brightener used to prepare 100 ml.

[0061] Table 4

[0062]

[0063] Performance Experiment

[0064] The plating solutions prepared in Examples 11-20 (using the brightener prepared in Examples 1-10) and the plating solutions prepared in Comparative Examples 6-10 (using the brightener prepared in Comparative Examples 1-15) were subjected to a Hull cell experiment:

[0065] Electroplating conditions: Pour 250 mL of plating solution into a 267 mL Hull cell, use a platinum-titanium plate as the anode, use a brass Hull cell test piece for the Hull cell experiment, stir with air, temperature 40-50°C, current 1A.

[0066] 1. Since the appearance of the coating is different at different heights of the cathode at the same distance, in order to better evaluate the results of the Hull cell test, the evaluation area of ​​the bright area is 25 cm above the bottom of the cathode.

[0067] 2. Alloy ratio test: Use the energy dispersive spectrometer (EDS) of the scanning electron microscope (SEM) to characterize and analyze the composition of the coating.

[0068] 3. Roughness test: The surface roughness of the coating is measured using a 3D surface profiler. The surface roughness is related to the scanning area. This test uses 100μm×100μm as the scanning area.

[0069] Test results: as shown in Table 5.

[0070] Table 5

[0071]

[0072] According to Table 5, it can be found that the coatings of Examples 11 to 20 are fully bright in the measurable current density range (0.1 to 4.5 ASD), with a roughness of <0.7 μm, and the co-deposition ratio of palladium to cobalt is between 60:40 and 90:10. The co-deposition ratio range is large and can meet different practical needs. The brighteners prepared in Comparative Examples 1, 2, and 3, which only contain a single benzenesulfonate, naphthalenesulfonate, or acetylamine, have a small bright area after being added to the plating solution, and the bright area is concentrated in the low current density area (below 2.5 ASD). Comparative Examples 4 and 5 contain multiple brighteners of the same type of components. Although the bright area of ​​the plating solution prepared therefrom increases after electroplating (0.5 to 3.5 ASD), it still does not reach full brightness.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents, and 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.

Claims

1. A brightener for palladium-cobalt alloy electroplating solution, characterized in that: An aqueous solution comprising component A and component B; The component A is selected from one or more compounds shown in formula I or formula II; wherein A1 is -(CH2)n-, n=0, 1 or 2; A2, A3, A4, A5 and A6 are each independently selected from -H, -OH, -CH3, -C2H5, -COOH, -CHO or -SO3M2; M1 and M2 are each independently selected from hydrogen ions or metal ions; wherein B1, B2, B3, B4, B5, B6, B7 and B8 are each independently selected from -H, -OH, -CH3, -C2H5, -COOH, -CHO or -SO3H; and at least one substituent among B1, B2, B3, B4, B5, B6, B7 and B8 is -SO3H; The B component is selected from one or more compounds shown in formula III; R1-C≡C-R2 (III) wherein R1 is selected from hydroxyl, alkyl substituted by at least one hydroxyl and / or amino group, alkoxy substituted by at least one hydroxyl, amino, amino substituted by at least one alkyl, amino substituted by at least one hydroxyl and one alkyl; R2 is selected from hydrogen, alkyl, hydroxyl, alkyl substituted by at least one hydroxyl group, and alkoxy substituted by at least one hydroxyl group.

2. The brightener for palladium-cobalt alloy electroplating solution according to claim 1, characterized in that: In the compound of formula I, at most two of A2, A3, A4, A5 and A6 are non-hydrogen substituents.

3. The brightener for palladium-cobalt alloy electroplating solution according to claim 2, characterized in that: The compound of formula I is 4. The brightener for palladium-cobalt alloy electroplating solution according to claim 1, characterized in that: The compounds of formula II B1, B2, B3, B4, B5, B6, B7 and B8 contain three or less -SO3H.

5. The brightener for palladium-cobalt alloy electroplating solution according to claim 4, characterized in that: The compound of formula II is 6. The brightener for palladium-cobalt alloy electroplating solution according to claim 1, characterized in that: The compound of formula III is 7. The brightener for palladium-cobalt alloy electroplating solution according to claim 1, characterized in that: The brightener for palladium-cobalt alloy electroplating solution has a weight ratio of component A to component B of (100-1000):(1-10), preferably, (40-200):

1.

8. A palladium-cobalt alloy electroplating solution, characterized in that: The brightener for palladium-cobalt alloy electroplating solution comprises the brightener for palladium-cobalt alloy electroplating solution according to any one of claims 1 to 7.

9. The palladium-cobalt alloy electroplating solution according to claim 8, characterized in that: The palladium-cobalt alloy electroplating solution also includes a palladium salt, a cobalt salt and a complexing agent.

10. The palladium-cobalt alloy electroplating solution according to claim 8, characterized in that: The distribution ratio of each component by weight is as follows:

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