CN115613084A - Cyanide-free alkali copper electroplating solution and use method thereof - Google Patents

Abstract

The application relates to the technical field of electroplating solution, and particularly discloses cyanide-free alkali copper electroplating solution and a using method thereof. A cyanide-free alkaline copper electroplating bath comprising: the cylinder opening agent is 500-900mL/L; 0.5-10mL/L of additive; pH regulator 5-20g/L; 0.1-2g/L of brightener; 0-40g/L of conductive salt; 0-20g/L of equilibrium liquid; the additive is a grain refining additive, and the additive is selected from at least one of polyether or amine compounds. The using method comprises the following steps: s1, preparing electroplating solution, and adjusting the pH value to 8.5-10.5; s3, electroplating: adjusting the current density to 0.1-2ASD, electroplating temperature to 45-53 deg.C, and electroplating for 1-10min. The electroplating solution can be used for priming and pre-plating copper processes of iron, stainless steel and the like, has the advantages of firm and bright plating layer combination and no cyanide, and is suitable for various electroplating modes such as continuous plating, dip plating and the like.

Description

Cyanide-free alkali copper electroplating solution and use method thereof

Technical Field

The application relates to the technical field of electroplating solutions, in particular to a cyanide-free alkali copper electroplating solution and a using method thereof.

Background

The copper plating solution comprises two major categories of copper plating solution, namely cyanide copper plating solution and cyanide-free copper plating solution, and the cyanide-free copper plating solution is environment-friendly, can completely replace the traditional cyanide copper plating process and bright copper plating process, and is suitable for any metal base material: the cyanide-free copper plating solution is gradually becoming a copper plating solution which is widely used at present on base materials such as pure copper, copper alloy, iron, stainless steel, zinc alloy die castings, aluminum alloy workpieces and the like.

At present, copper powder is easy to replace at an anode in the using process of cyanide-free copper plating solution, the bonding firmness between a formed plating layer and a base material is poor, and in order to improve the performance of the cyanide-free copper plating solution, a complexing agent is usually added into the cyanide-free copper plating solution, and the bonding performance or the replacement performance of the cyanide-free copper plating solution is improved through the complexing agent.

For the above-mentioned related art, currently conventional complexing agents are, for example: complexing agents such as tartrate and pyrophosphate can only improve the plating layer bonding effect or copper powder replacement defect of the cyanide-free copper plating solution, and a cyanide-free copper plating solution with good plating layer bonding effect and capable of inhibiting anode copper replacement precipitation is urgently needed.

Disclosure of Invention

The application provides a cyanide-free alkaline copper electroplating solution and a using method thereof, in order to obtain the cyanide-free copper electroplating solution which has good plating layer combination effect and inhibits displacement precipitation of anode copper.

In a first aspect, the present application provides a cyanide-free alkaline copper electroplating solution, which adopts the following technical scheme:

a cyanide-free alkaline copper electroplating bath comprising:

the cylinder opening agent is 500-900mL/L;

0.5-10mL/L of additive;

pH regulator 5-20g/L;

0.1-2g/L of brightener;

20-40g/L of conductive salt;

0-20g/L of balance liquid;

the jar opener comprises 1-10g/L of divalent copper ions and 70-90g/L of organic acid salt, wherein the organic acid salt comprises tartrate;

the additive is selected from at least one of polyether or amine compound.

Preferably, the tartrate salt is selected from potassium tartrate or sodium tartrate.

By adopting the technical scheme, firstly, tartrate is preferably used as the organic acid salt in the technical scheme, the tartaric acid can effectively inhibit the displacement of copper, the formed complex mixture has strong binding force, and the dispersing capacity and the covering capacity of the plating solution are good. Secondly, polyether or amine compounds are selected as additives, and are matched with tartrate for auxiliary complexation, so that crystal grains are refined, the arrangement effect of the crystal grains is regulated, and the compactness and the bonding firmness of the coating are improved.

The polyether is used as an additive, and generally has higher surface activity, so that the polarization degree of deposited copper can be improved, the crystallization refinement is promoted, the diffusion speed of copper ions is improved, the possibility of agglomeration and accumulation of the copper ions is reduced, the particle size of copper grains and the dispersion uniformity of the copper particles are optimized, and the flatness of a plating layer is improved.

The amine compound is used as an additive, and can complex copper ions in the electroplating solution, and the formed complex has high stability, so that the overpotential of copper ion deposition is increased, the cathode polarization is increased, the crystallization refinement is promoted, and the compactness of the plating layer is improved.

The polyether and the amine compound are adopted to be matched as additives, the amine compound is used for complexing copper ions to form a stable complex, the surface activity of the polyether is utilized to improve the uniform dispersion degree of the complex in electroplating solution, the diffusion coefficient of crystal grains is improved, the differential capacitance is increased, the cathode polarization is enhanced, and the nucleation potential is repeated, so that a smooth, fine and firmly-combined coating is obtained.

In addition, the plating liquid does not contain cyanide and pyrophosphoric acid-based compounds, and the treatment can be carried out conveniently by treating general metal wastewater.

Preferably, the divalent copper ions are selected from any one or more of copper sulfate, copper chloride, copper nitrate and basic copper carbonate.

Through adopting above-mentioned technical scheme, optimized the kind of bivalent copper ion in this application, suitable copper salt can decompose in the plating solution and produce copper ion, maintains the content of copper ion in the plating solution.

Preferably, the polyether compound includes any one of hydroxyethyl cellulose, polyethylene glycol, polyoxyethylene castor oil, OP emulsifier, polyethylene glycol formal.

Preferably, the polyether compound is hydroxyethyl cellulose, and the addition amount of the hydroxyethyl cellulose is 0.1-2.5mg/L.

By adopting the technical scheme, firstly, the polyether compound has excellent surface activity, so that not only is the complexation assisted, but also the bonding firmness between the complex and the matrix is enhanced.

In the technical scheme, hydroxyethyl cellulose is preferably added into the electroplating solution, the hydroxyethyl cellulose can refine the particle size of copper particles and level the coating, and the hydroxyethyl cellulose is directionally adsorbed on active sites on the surface of the cathode to form a passivation film, so that the surface diffusion of copper ions is inhibited, the growth rate of crystal grains is inhibited, and the crystal grains are refined. Meanwhile, polarization resistance is increased in the directional adsorption process, and the current density difference on the surface of the cathode is reduced, so that copper ions can be uniformly deposited on the surface of the cathode. The hydroxyethyl cellulose is used as a nonionic surfactant, so that the wettability of electrolyte to an electrode is improved, the overflow of hydrogen bubbles is promoted, and the defects of vacuum, depression and the like of a plating layer are reduced.

In addition, the addition amount of the hydroxyethyl cellulose is optimized in the technical scheme, the proper addition amount of the hydroxyethyl cellulose can inhibit the reduction reaction of copper ions, the overpotential of the reaction is improved, the nucleation number is increased, the crystal grains are refined, the uniformity of the crystal grain shape is increased, and the surface smoothness of the coating is improved. The excessive addition of the hydroxyethyl cellulose causes overlarge polarization degree, excessively strong inhibition of grain growth and poor particle size uniformity, and reduces the bonding effect between the coating and the base material and the surface smoothness.

Preferably, the amine compound is selected from any one of saccharin sodium, hydroxyethyl ethylenediamine and N, N-diethyl ethylenediamine.

By adopting the technical scheme, saccharin sodium is preferably added into the electroplating solution in the technical scheme, and the saccharin sodium is adsorbed on the surface of the cathode through lone-pair electrons in sulfur, oxygen and nitrogen atoms, so that the nucleation rate is increased, the grain refinement is promoted, and a compact coating is formed.

Hydroxyethyl ethylenediamine or N, N-diethyl ethylenediamine is added into the electroplating solution, so that the additive has active amino and hydroxyl, and the additive is matched with divalent copper ions in the tartrate complex electroplating solution to play a role in obviously inhibiting copper powder precipitation and accelerating electrodeposition rate, and the obtained coating is compact and has excellent binding force.

Preferably, the additive further comprises sodium polydithio dipropyl sulfonate.

Preferably, the addition amount of the sodium polydithio-dipropyl sulfonate is 0.2-0.4mg/L.

By adopting the technical scheme, the sodium polydithio-dipropyl sulfonate has a inhibition effect on the electrodeposition process of copper, and is complexed with discharge metal cations, so that the formed complex cannot be directly discharged, needs to be converted into copper ions after dissociation and then converted into copper atoms, slows down the reaction rate and has a refining effect on crystal grains.

The additive also contains hydroxyethyl cellulose, when the sodium polydithio-dipropyl sulfonate and the hydroxyethyl cellulose are used in a matching way, the sodium polydithio-dipropyl sulfonate has an accelerating effect, the hydroxyethyl cellulose has the effect of an inhibitor, the hydroxyethyl cellulose and the sodium polydithio-dipropyl sulfonate compete for adsorption, the inhibiting effect of the hydroxyethyl cellulose is adjusted, and the possibility that crystal grains cannot grow sufficiently is reduced; and a crystal nucleus which grows rapidly can be formed to fill gaps among the particles, so that copper particles are refined, and the surface compactness of the plating layer is improved. The application optimizes the addition amount of the sodium polydithio-dipropyl sulfonate, the appropriate addition amount enables the matching effect between the components of the additive to be excellent, refined and uniform copper particles are obtained, copper powder precipitation is inhibited, and a plating layer with a smooth and uniform surface is obtained.

Preferably, the additive further comprises copper whiskers, and gelatin is wrapped outside the copper whiskers.

Through adopting above-mentioned technical scheme, this application is preferred to adopt and adds copper whisker and gelatin in the plating solution, and amino and hydrogen ion in the gelatin combine to be the cation, can move and adsorb to the cathode towards the cathode under the electric field effect, because gelatin parcel is outside the copper whisker, consequently when gelatin supported on the cathode, drive the copper whisker and load on the cathode, increase the roughness on cathode surface, and then strengthen the bonding fastness between cladding material and the cathode on follow-up cathode.

Preferably, the additive further comprises aminotrimethylene phosphonic acid and an alkynol compound, wherein the alkynol compound comprises any one of a propargyl alcohol ethoxy compound, 3-methyl-1-pentyn-3-ol, 1,1,3-triphenyl-2-propiolic alcohol, hydroxypropyl propargyl ether and 3-methylbutynol.

Through adopting above-mentioned technical scheme, preferably adopt amino trimethylene phosphonic acid and alkynol compound cooperation to add to the plating solution among the technical scheme of this application, the deposit potential of copper ion obviously moves negatively, and alkynol compound adsorbs and forms inseparable adsorbed layer on the cathode surface promptly, improves the bonding fastness between cladding material and the cathode to hinder copper complex ion discharge process or surface diffusion, refine the cladding material crystallization, restrain the copper powder and precipitate, and improve the bright effect of cladding material. And the alkynol compound also has excellent corrosion inhibition effect, so that the plating layer loaded on the cathode is passivated and has excellent corrosion inhibition effect.

Preferably, the conductive salt is selected from any one or more of potassium chloride, potassium sulfate, sodium chloride, potassium tartrate, potassium dihydrogen phosphate and dipotassium hydrogen phosphate.

In a second aspect, the application provides a method for using a cyanide-free alkaline copper electroplating solution, which adopts the following technical scheme:

the application method of the cyanide-free alkali copper electroplating solution comprises the following steps:

s1, preparing an electroplating solution: taking the cylinder opening agent, the brightening agent, the conductive salt, the additive and water, stirring and mixing, adding the pH regulator, and regulating the pH to 8.5-10.5 to obtain electroplating solution;

s2, pretreatment of a plated part: washing the electroplated part for multiple times by water washing, chemical oil removal, hot water washing, acid washing, water washing and the like to obtain a pretreated electroplated part;

s3, electroplating: and (3) immersing the pretreated electroplated part in electroplating solution, adjusting the current density to 0.1-2ASD, and electroplating for 1-10min at the electroplating temperature of 45-53 ℃ to obtain the copper-plated part.

By adopting the technical scheme, the current density, the electroplating temperature and the electroplating time in the electroplating process are optimized, the proper current density enables the coating to be bright to semi-bright without white fog, the dispersion capacity of the coating is better, and the coating which is firmly combined can be formed; meanwhile, the pH value of electroplating is optimized, the brightness degree and the density of the plating layer can be further enhanced by proper pH value, and the overall effect of the plating layer is improved.

In summary, the present application has the following beneficial effects:

1. because the tartrate is used as the organic acid salt, the tartaric acid can effectively inhibit the displacement of copper, the formed complex mixture has stronger binding force, and the dispersing capacity and the covering capacity of the plating solution are better. Secondly, polyether or amine compounds are selected as additives, and are matched with tartrate for auxiliary complexation, so that crystal grains are refined, the arrangement effect of the crystal grains is regulated, and the compactness and the bonding firmness of the coating are improved. The polyether and the amine compound are matched to be used as additives, the amine compound is used for complexing copper ions to form a stable complex, the surface activity of the polyether is used for improving the dispersion uniformity of the complex in electroplating liquid, the crystal grain diffusion coefficient is improved, the differential capacitance is increased, the cathode polarization is enhanced, the nucleation potential is repeated, a smooth and fine coating is obtained, and the binding firmness of the coating is good.

2. In the application, preferably, hydroxyethyl cellulose is added into the electroplating solution, the hydroxyethyl cellulose can refine the particle size of copper particles and level the coating, and the hydroxyethyl cellulose is directionally adsorbed on active sites on the surface of a cathode to form a passive film, so that the surface diffusion of copper ions is inhibited, the growth rate of crystal grains is inhibited, and the crystal grains are refined. Meanwhile, the polarization resistance can be increased in the directional adsorption process, and the current density difference on the surface of the cathode is reduced, so that copper ions can be uniformly deposited on the surface of the cathode. The hydroxyethyl cellulose is used as a nonionic surfactant, so that the wettability of electrolyte to an electrode is improved, the overflow of hydrogen bubbles is promoted, and the defects of vacuum, depression and the like of a plating layer are reduced.

In addition, the addition amount of the hydroxyethyl cellulose is optimized in the technical scheme, the proper addition amount of the hydroxyethyl cellulose can inhibit the reduction reaction of copper ions, the overpotential of the reaction is improved, the nucleation number is increased, the crystal grains are refined, the uniformity of the crystal grain shape is increased, and the surface smoothness of the coating is improved. The excessive addition of the hydroxyethyl cellulose causes overlarge polarization degree, excessively strong inhibition of grain growth and poor particle size uniformity, and reduces the bonding effect between the coating and the base material and the surface smoothness.

3. When the sodium polydithio-dipropyl sulfonate and the hydroxyethyl cellulose are matched for use, the sodium polydithio-dipropyl sulfonate has an accelerating effect, the hydroxyethyl cellulose plays a role of an inhibitor, the hydroxyethyl cellulose and the sodium polydithio-dipropyl sulfonate compete for adsorption, the inhibiting effect of the hydroxyethyl cellulose is adjusted, and the possibility that crystal grains cannot fully grow is reduced; and a crystal nucleus which grows rapidly can be formed to fill gaps among the particles, so that copper particles are refined, and the surface compactness of the plating layer is improved.

4. The electroplating solution does not contain cyanide and pyrophosphoric acid compounds, is beneficial to wastewater treatment, can be applied to various electroplating modes such as continuous plating, immersion plating, rack plating and barrel plating, is suitable for priming pre-plating processes of iron, iron alloy, brass and the like, and can directly replace a cyanide copper plating process.

Detailed Description

The present application will be described in further detail with reference to examples.

Preparation example

Preparation of tartrate salt

Preparation example 1

Sodium tartrate is taken as tartrate, the tartrate can be sodium tartrate or potassium tartrate, and sodium tartrate is selected in the preparation example.

Preparation of polyether Compound

Preparation example 2

Hydroxyethyl cellulose was used as the polyether compound 1.

Preparation example 3

The polyether compound 2 was prepared from polyethylene glycol.

Of note, polyether compounds include, but are not limited to: one of hydroxyethyl cellulose, polyethylene glycol, polyoxyethylene castor oil, OP emulsifier, and polyethylene glycol formal.

Preparation of amine Compound

Preparation example 4

Taking saccharin sodium as an amine compound 1.

Preparation example 5

Taking hydroxyethyl ethylenediamine as the amine compound 2.

Of these, it is worth mentioning that amine compounds include, but are not limited to: saccharin sodium, hydroxyethyl ethylenediamine, and N, N-diethyl ethylenediamine.

Preparation of alkynol Compound

Preparation example 6

Taking 3-methyl-1-pentyne-3-ol as an alkynol compound.

Of these, it is worth mentioning that alkynol compounds include, but are not limited to: any one of propiolic alcohol ethoxy compound, 3-methyl-1-pentyne-3-ol, 1,1,3-triphenyl-2-propiolic alcohol, hydroxypropyl propargyl ether and 3-methylbutinol.

Preparation of conductive salt

Preparation example 7

Potassium chloride was taken as the conductive salt 1.

Preparation example 8

Taking potassium tartrate as conductive salt 2.

Among them, it is worth mentioning that the conductive salt includes but is not limited to: the conductive salt is selected from one or more of potassium chloride, potassium sulfate, sodium chloride, potassium tartrate, potassium dihydrogen phosphate and dipotassium hydrogen phosphate.

Example of preparation of divalent copper ion

Preparation example 9

Taking copper sulfate as bivalent copper ions.

Among them, it is worth mentioning that the divalent copper ions include but are not limited to: copper sulfate, copper chloride, copper nitrate, basic copper carbonate.

Preparation of Cylinder opener agent

Preparation examples 10 to 12

Taking copper sulfate and sodium tartrate, wherein the specific mass is shown in Table 1, mixing, and preparing the caldron starter 1-3.

TABLE 1 preparation examples 10-12 compositions of jar opener

Examples of preparation of additives

Preparation examples 13 to 19

Polyether compound 1, amine compound, sodium polydithio-dipropyl sulfonate, aminotrimethylene phosphonic acid and alkynol compound are respectively taken, the specific mass is shown in table 2, and additives 1-7 are prepared.

TABLE 2 preparation examples 13 to 19 additive compositions

The amount of polyether compound 1 added in preparation example 16 may be 0.1mg/L, or 1mg/L, or 1.5mg/L, or 2.5mg/L, and in this preparation example, 1.5mg/L is preferred.

The preparation method of the copper whisker comprises the following steps: the copper whiskers and gelatin were mixed with stirring to obtain gelatin-coated copper whiskers, which were added to preparation examples 18 to 19.

Preparation example 20

The difference from preparation 15 is that: an additive 8 was prepared by using an equal mass of the polyether compound 2 in place of the polyether compound 1 in preparation example 15.

Preparation example 21

The difference from preparation example 15 is that: an additive 9 was prepared by using an amine compound 2 of equal mass in place of the amine compound 1 in preparation example 15.

Preparation example 22

The difference from preparation 16 is that: the additive 10 was prepared with 0.3mg/L sodium polydithio-dipropanesulfonate.

Preparation example 23

The difference from preparation 16 is that: the additive 11 was prepared with 0.3mg/L sodium polydithio-dipropanesulfonate.

Examples

Examples 1 to 3

In one aspect, the present application provides a cyanide-free alkaline copper electroplating bath comprising: the contents of the vat opening agent 1, the additive, the pH regulator, the brightener, the conductive salt 1 and the balance liquid are shown in a table 3.

In another aspect, the present application provides a method for preparing a high compacted phosphate type positive electrode material, comprising the steps of:

s1, preparing an electroplating solution: taking the cylinder opening agent 1, the brightening agent, the conductive salt 1, the additive and water, stirring and mixing with air, adding a pH regulator, regulating the pH to 8.5, and continuously filtering by using a 5-10 micron filter element to obtain electroplating solution;

s2, pretreatment of a plated part: washing the electroplated part for multiple times by water washing, chemical oil removal, hot water washing, acid washing, water washing and the like to obtain a pretreated electroplated part;

s3, electroplating: and (3) immersing the pretreated electroplated part in electroplating solution, adjusting the current density to 0.1ASD, and electroplating for 1min at the electroplating temperature of 45 ℃ to obtain a copper-plated part 1-4.

The equilibrium solution was an ammonia-ammonium chloride buffer (pH = 10).

TABLE 3 examples 1-4 electroplating bath compositions

Examples 5 to 12

The difference from example 3 is that: copper-plated articles 5 to 12 were prepared using additives 2 to 9 in equal mass concentrations instead of additive 1 in example 3.

Examples 13 to 14

The difference from example 3 is that: copper-plated articles 13 to 14 were prepared using the same mass concentration of the opening agent 2 to 3 in place of the opening agent 1 in example 3.

Example 15

The difference from example 3 is that: a copper-plated article 15 was prepared using the conductive salt 2 at an equal mass concentration instead of the conductive salt 1 in example 3.

Example 16

The difference from example 3 is that:

s1, preparing electroplating solution: taking the cylinder opening agent 1, the brightening agent, the conductive salt 1, the additive and water, stirring and mixing, adding the pH regulator, and regulating the pH to 9.5 to obtain electroplating solution;

s2, pretreatment of a plated part: washing the electroplated part for many times by water washing, chemical degreasing, hot water washing, acid washing, water washing and the like to obtain a pretreated electroplated part;

s3, electroplating: and (3) immersing the pretreated electroplated part in electroplating solution, adjusting the current density to be 1ASD, and electroplating for 5min at the electroplating temperature of 50 ℃ to obtain a copper-plated part 16.

Example 17

The difference from example 3 is that:

s1, preparing an electroplating solution: taking the cylinder opening agent 1, the brightening agent, the conductive salt 1, the additive and water, stirring and mixing, adding the pH regulator, and regulating the pH to 10.5 to obtain electroplating solution;

s2, pretreatment of a plated part: washing the electroplated part for multiple times by water washing, chemical oil removal, hot water washing, acid washing, water washing and the like to obtain a pretreated electroplated part;

s3, electroplating: the pretreated plated article was immersed in an electroplating solution, and the current density was adjusted to 1ASD, the electroplating temperature was 53 ℃, and electroplating was performed for 10min to obtain a copper-plated article 17.

Examples 18 to 19

The difference from example 3 is that: copper-plated articles 18-19 were prepared using additives 10-11 at equal mass concentrations instead of additive 1 in example 3.

Comparative example

Comparative example 1

This comparative example differs from example 3 in that no additive 1 was present, a plating solution was prepared, and a copper-plated article 20 was prepared.

Performance test

(1) And (4) testing the stability of the plating solution: using palladium chloride accelerated test, 15mL of PdCl was added to 50mL of plating solution ₂ (0.18 g/L), the bath decomposition time is recorded.

(2) And (3) detection of apparent performance of the plating layer: visual inspection and gloss measurement were used to determine the appearance and covering power of the coatings. The visual measurement method is based on the gloss and roughness of the surface of the plating layer. The coating gloss was measured using a gloss meter at a refraction angle of 60 °. Roughness: the surface roughness was measured using an optical microscope (OlympusDSX 510). The magnification was 555 times and the sampling length was 250 μm, 3 different positions were measured for each sample, 3 times for the same position, and the average was taken.

(3) And (3) detecting the binding force: according to a bending method in the national standard GB/T5270-2005 test method for the metal covering layer electrodeposition and chemical deposition layer adhesion strength on a metal substrate, a copper-plated part is bent for multiple times by 90 degrees, whether peeling, stripping and falling phenomena exist or not is observed, and the peeling bending times of the silver-plated part are recorded.

TABLE 5 Performance test of examples 1-19, comparative example 1

The comparison of the performance tests in combination with table 2 can find that:

(1) A comparison of examples 1 to 4, examples 16 to 17 and comparative example 1 shows that: the stability of the electroplating solutions prepared in examples 1-4 and examples 16-17, the appearance, the gloss and the bonding firmness of the plating layers are all improved, and the roughness is reduced, which shows that the polarization degree of the deposited copper is improved, the crystal refinement is promoted, the diffusion speed of copper ions is improved, the possibility of copper ion agglomeration and accumulation is reduced, the particle size of copper crystal grains and the dispersion uniformity of copper particles are optimized, and the flatness of the plating layers is improved by adding the polyether compound in the application. Simultaneously, optimized each parameter of electroplating in the electroplating process in this application, suitable current density makes the cladding material bright to half bright no white fog, and the dispersion ability of cladding material is preferred, can form the cladding material that combines firmly.

(2) Comparison with examples 5-6 and example 3 can show that: the stability, appearance, gloss and bonding firmness of the plating solutions prepared in examples 5-6 were improved and the roughness was reduced, which indicates that the present application, using a combination of polyether and amine compounds as additives, improved the diffusion coefficient of the grains, increased the differential capacitance, enhanced the cathodic polarization, and repeated the nucleation potential to obtain smooth and fine plating layers.

(3) A comparison of examples 7-10, examples 11-12, examples 18-19 and example 3 has been found: the stability, appearance, gloss and bonding firmness of the plating solutions prepared in examples 7-12 were improved and the roughness was reduced, which indicates that the sodium polydithio dipropyl sulfonate in the present application has the effects of inhibiting the copper electrodeposition process, slowing down the reaction rate and refining the crystal grains. When the sodium polydithio-dipropyl sulfonate and the hydroxyethyl cellulose are matched for use, copper particles are thinned, and gaps among the particles are filled until the surface is compact. The addition amount of the poly-dithio-dipropyl sodium sulfonate is proper, so that refined and uniform copper particles are obtained, and the precipitation of copper powder is inhibited.

The amino trimethylene phosphonic acid is matched with the alkynol compound, so that the potential negative shift is realized, a tight adsorption layer is formed, the discharge process or surface diffusion of copper complex ions is hindered, the crystallization of a plating layer is refined, and the brightness is improved.

Copper whisker and gelatin cooperation, gelatin complex are cation and adsorb to the cathode surface, increase the roughness on cathode surface, and then strengthen the bonding fastness between follow-up coating and the negative pole on the negative pole.

(4) A comparison of examples 13 to 14, example 15 and examples 1 to 3 shows that: the stability, appearance, gloss and bonding firmness of the plating solutions prepared in examples 13 to 15 were all improved, and the roughness was reduced, which indicates that tartaric acid was used as an organic acid salt in the present application, and the tartaric acid was able to effectively inhibit the displacement of copper, and the formed complex mixture had a strong bonding force, and the plating solutions had good dispersing ability and covering ability.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (8)

1. A cyanide-free alkaline copper electroplating bath, comprising:

the cylinder opening agent is 500-900mL/L;

0.5-10mL/L of additive;

pH regulator 5-20g/L;

0.1-2g/L of brightener;

20-40g/L of conductive salt;

0-20g/L of equilibrium liquid;

the biscuit cleaning agent comprises 1-10g/L of cupric ions and 70-90g/L of organic acid salt, wherein the organic acid salt comprises tartrate;

the additive is a grain refining additive, and the additive is selected from at least one of polyether or amine compounds.

2. The cyanide-free alkaline copper plating bath according to claim 1, wherein: the divalent copper ions are selected from any one or more of copper sulfate, copper chloride, copper nitrate and basic copper carbonate.

3. The cyanide-free alkaline copper plating bath according to claim 1 wherein: the polyether compound comprises any one of hydroxyethyl cellulose, polyethylene glycol, polyoxyethylene castor oil, OP emulsifier and polyethylene glycol formal.

4. The cyanide-free alkaline copper plating bath according to claim 1 wherein: the amine compound is any one of saccharin sodium, hydroxyethyl ethylenediamine and N, N-diethyl ethylenediamine.

5. The cyanide-free alkaline copper plating bath according to claim 3, wherein: the additive also comprises sodium polydithio-dipropyl sulfonate.

6. The cyanide-free alkaline copper plating bath according to claim 1 wherein: the additive also comprises amino trimethylene phosphonic acid and alkynol compounds, wherein the alkynol compounds comprise any one of propargyl alcohol ethoxy compounds, 3-methyl-1-pentyne-3-ol, 1,1,3-triphenyl-2-propiolic alcohol, hydroxypropyl propargyl ether and 3-methyl butynol.

7. The cyanide-free alkaline copper plating bath according to claim 1 wherein: the conductive salt is selected from one or more of potassium chloride, potassium sulfate, sodium chloride, potassium tartrate, potassium dihydrogen phosphate and dipotassium hydrogen phosphate.

8. The method of using a cyanide-free alkaline copper plating bath according to any of claims 1-7, comprising the steps of:

s1, preparing electroplating solution: taking the cylinder opening agent, the brightening agent, the conductive salt, the additive and water, stirring and mixing, adding the pH regulator, and regulating the pH to 8.5-10.5 to obtain electroplating solution;

s2, pretreatment of a plated part: washing the electroplated part for multiple times by water washing, chemical oil removal, hot water washing, acid washing, water washing and the like to obtain a pretreated electroplated part;

s3, electroplating: and (3) immersing the pretreated electroplated part in electroplating solution, adjusting the current density to 0.1-2ASD, and electroplating for 1-10min at the electroplating temperature of 45-53 ℃ to obtain the copper-plated part.