阅读说明：本技术 一种化学镀锡液及其制备方法、使用 (Chemical tin plating solution and preparation method and application thereof ) 是由 张元正 张本汉 于 2020-07-28 设计创作，主要内容包括：本发明属于表面处理技术领域,具体的,涉及一种化学镀锡液及其制备方法、应用。本发明的提供了一种化学镀锡液,按照浓度包括：锡盐5-25g/L,络合剂70-80g/L,硫脲类物质100-120g/L,表面活性剂1-10g/L,还原剂40-70g/L,MZxOy 1-10g/L,其中M为V、Nb、Zr、Na中的至少一种；Z为杂元素；x为0-2；y为3-5。本申请人通过精心研究的化学镀锡液,各个组分相互协同,共同发挥作用,沉积速率快,镀层厚度大,镀层均匀致密。(The invention belongs to the technical field of surface treatment, and particularly relates to a chemical tin plating solution, and a preparation method and application thereof. The invention provides an electroless tin plating solution, which comprises the following components in concentration: 5-25g/L of tin salt, 70-80g/L of complexing agent, 100-120g/L of thiourea substance, 1-10g/L of surfactant, 40-70g/L of reducing agent and 1-10g/L of MZxOy, wherein M is at least one of V, Nb, Zr and Na; z is a hetero element; x is 0 to 2; y is 3 to 5. The applicant researches the chemical tin plating solution in a meticulous way, and all the components are mutually cooperated to play a role together, so that the deposition rate is high, the thickness of a plating layer is large, and the plating layer is uniform and compact.)

1. An electroless tin plating solution, comprising, in terms of concentration: 5-25g/L of tin salt, 70-80g/L of complexing agent, 100-120g/L of thiourea substance, 1-10g/L of surfactant, 40-70g/L of reducing agent and MZxOy1-6g/L, wherein M is at least one of V, Nb, Zr and Na; z is a hetero element; x is 0 to 2; y is 3 to 5.

2. The electroless tin plating solution according to claim 1, wherein the tin salt is at least one selected from the group consisting of tin methane sulfonate, tin hydrochloride, tin sulfate, and stannous fluoroborate.

3. The electroless tin plating solution of claim 1, wherein the complexing agent comprises at least one of citric acid, malic acid, citric acid, tartaric acid.

4. The electroless tin plating solution of claim 1, wherein the reducing agent is selected from at least one of sodium hypophosphite, titanium chloride, ammonium hypophosphite, potassium hypophosphite, borohydride, and hydrazine hydrate.

5. The electroless tin plating solution of claim 1, wherein MZxOy, wherein M is at least one of V, Na; z is a hetero element; x is 0 to 2; y is 3 to 5.

6. The electroless tin plating solution of claim 1, wherein the surfactant is selected from at least one of cetyltrimethylammonium bromide, dodecyltrimethylammonium chloride, polyethylene glycol, polyoxyethylene polyoxypropylene block copolymer.

7. The electroless tin plating solution as claimed in claim 6, wherein the average molecular weight of the polyoxyethylene polyoxypropylene block copolymer is 2000-2800.

8. The electroless tin plating solution according to claim 1, further comprising 16 to 20g/L of an unsaturated compound containing a polar group.

9. A method for preparing an electroless tin plating solution according to any one of claims 1 to 8, comprising the steps of: the components are mixed evenly.

10. A method of using the electroless tin plating solution according to any one of claims 1 to 8, wherein the electroless tin plating solution is applied under the condition of 40 to 45 ℃ for 10 to 15 min.

Technical Field

The invention belongs to the technical field of surface treatment, and particularly relates to a chemical tin plating solution, and a preparation method and application thereof.

Background

Tin is a silvery white metal, has the advantages of corrosion resistance, no toxicity, easy brazing and the like, and is widely applied to various fields in industrial production. Such as tin food packaging boxes and electronic component soldering layers. Based on the good solderability and corrosion resistance of tin, tin plating also has great application value in printing electroplating plates and ultra-large scale integrated circuit chips. In the early electronic packaging and electronic circuit board, tin-lead alloy is used as a solderable plating layer, and the electronic packaging and electronic circuit board has the advantages of low-temperature soldering, high bonding force, no tin whisker generation and the like.

In recent years, people pay more and more attention to health and environmental problems, and a tin-plated layer is widely applied to the industries of electronic components and semiconductor packaging which take copper and copper alloy as a base body as a solderable plating layer. Tin plating can be classified into hot dip tin plating, electrolytic tin plating and chemical tin plating according to the development process. Electroless plating is a process in which metal ions are deposited on the active surface of a substrate in a plating solution under the action of a reducing agent. Generally, the method is classified into a displacement method and a reduction method, and the displacement method deposits a thin metal coating on the surface of a substrate according to the displacement principle, so that the application is limited. The reduction method is a process of continuously depositing metal on the surface of a substrate by using a reducing agent in the plating solution, and plating layers with different thicknesses can be obtained according to requirements. The chemical plating has the advantages of good dispersion capability and covering capability of plating solution, uniform thickness of plating layer and no need of external power supply.

However, the development of the chemical tin plating solution is limited by the influence of the properties of tin and the plating conditions, such as thin plating thickness and slow deposition speed.

Disclosure of Invention

In order to solve the above technical problems, a first aspect of the present invention provides an electroless tin plating solution comprising, in terms of concentration: 5-25g/L of tin salt, 70-80g/L of complexing agent, 100-120g/L of thiourea substance, 1-10g/L of surfactant, 40-70g/L of reducing agent and 1-6g/L of MZxOy, wherein M is at least one of V, Nb, Zr and Na; z is a hetero element; x is 0 to 2; y is 3 to 5.

As a preferred technical scheme, the tin salt is at least one selected from tin methane sulfonate, tin hydrochloride, tin sulfate and stannous fluoroborate.

As a preferable technical scheme, the complexing agent comprises at least one of citric acid, malic acid, citric acid and tartaric acid.

As a preferred technical solution, the reducing agent is at least one selected from sodium hypophosphite, titanium chloride, ammonium hypophosphite, potassium hypophosphite, borohydride and hydrazine hydrate.

As a preferred technical solution, said MZxOy, wherein M is at least one of V, Na; z is a hetero element; x is 0 to 2; y is 3 to 5.

As a preferred technical scheme, the surfactant is selected from at least one of cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium chloride, polyethylene glycol and polyoxyethylene polyoxypropylene block copolymer.

As a preferable embodiment, the average molecular weight of the polyoxyethylene polyoxypropylene block copolymer is 2000-2800.

As a preferable technical scheme, the chemical tin plating solution also comprises 16-20g/L of unsaturated compound containing polar groups.

The second aspect of the present invention provides a method for preparing the electroless tin plating solution, comprising the steps of: the components are mixed evenly.

The third aspect of the invention provides a using method of the chemical tin plating solution, wherein the plating condition of the chemical tin plating solution is 40-45 ℃, and the time is 10-15 min.

Has the advantages that: the applicant researches the chemical tin plating solution in a meticulous way, and all the components are mutually cooperated to play a role together, so that the deposition rate is high, the thickness of a plating layer is large, and the plating layer is uniform and compact.

Detailed Description

In order to solve the above problems, the present invention provides an electroless tin plating solution comprising, in terms of concentration: 5-25g/L of tin salt, 70-80g/L of complexing agent, 100-120g/L of thiourea substance, 1-10g/L of surfactant, 40-70g/L of reducing agent and 1-6g/L of MZxOy, wherein M is at least one of V, Nb, Zr and Na; z is a hetero element; x is 0 to 2; y is 3 to 5.

Preferably, the method comprises the following steps according to the concentration: 10-20g/L of tin salt, 70-80g/L of complexing agent, 100-120g/L of thiourea substance, 2-10g/L of surfactant, 40-60g/L of reducing agent and 1-3g/L of MZxOy, wherein M is at least one of V, Nb, Zr and Na; z is a hetero element; x is 0 to 2; y is 3 to 5.

Preferably, the tin salt is at least one selected from tin methane sulfonate, tin hydrochloride, tin sulfate and stannous fluoroborate. Tin salt can be selected according to the requirement, for example, tin methane sulfonate is selected, the toxicity is relatively low, the wastewater treatment is simple, and the plating layer is fine and smooth and is nano-scale crystal grains.

Preferably, the complexing agent comprises at least one of citric acid, malic acid, citric acid and tartaric acid. The complexing agent can generate a stable complex with tin ions, and tin liquid loss caused by direct reaction of tin and a reducing agent is prevented.

Preferably, the thiourea substances are selected from at least one of thiourea, thiosemicarbazide, vinylthiourea, divinylthiourea, 2, 3-indole dione 3-thiosemicarbazone, pyruvic acid thiosemicarbazone, acetone 4-phenyl-3-thiosemicarbazone and 2-butanone thiosemicarbazone. Preferably, the thiourea substances comprise thiourea and 2, 3-indole dione 3-thiosemicarbazone; the concentration ratio of the thiourea to the 2, 3-indole dione 3-thiosemicarbazone is 2-4: 1.

the reducing agent is selected from at least one of sodium hypophosphite, titanium chloride, ammonium hypophosphite, potassium hypophosphite, borohydride and hydrazine hydrate; the reducing agent is capable of promoting the reduction of tin ions.

The MZxOy, wherein M is at least one of V, Nb, Zr and Na; z is a hetero element; x is 0 to 2; y is 3 to 5. For example, M is a combination of V and Na elements, and M is a combination of Nb and Na elements; preferably, M is Na 2W; x is 0 and y is 4.

Because the hydrogen evolution potential of tin metal is too high in the chemical tinning process and the self-catalytic reduction capability is not available, the reducing agent is added to catalyze the tin to deposit through the hydrogen evolution reduction reaction; however, the existing reducing agents such as sodium hypochlorite, hydrazine hydrate and formaldehyde cannot effectively reduce tin, and the plating temperature cannot be higher than 45 ℃ in consideration of the influence of a PCB soft board circuit, so that the tin plating speed is slow, and the thickness of a plating layer is difficult to reach 1 mu m; applicants have found that when a certain amount of sodium hypophosphite is added, along with a thiourea-like material, MZxOy, Cu is promoted⁺Electrode potential of/Cu and Sn²⁺The potential difference between the/Sn electrode potentials is increased continuously, the deposition speed and the coating thickness are improved, and particularly M is Na 3V; when x is 0 and y is 4, the deposition speed exceeds 8 μm/h, and the thickness of the coating reaches nearly 1 μm.

The surfactant is selected from at least one of cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium chloride, polyethylene glycol and polyoxyethylene polyoxypropylene block copolymer; preferably, the polyoxyethylene polyoxypropylene block copolymer has an average molecular weight of 2000-2800; more preferably, the polyoxyethylene polyoxypropylene block copolymer comprises a first polyoxyethylene polyoxypropylene block copolymer and a second polyoxyethylene polyoxypropylene block copolymer; the average molecular weight of the first polyoxyethylene polyoxypropylene block copolymer is 2000-2400, and the average molecular weight of the second polyoxyethylene polyoxypropylene block copolymer is 2400-2800; the weight ratio of the first polyoxyethylene polyoxypropylene block copolymer to the second polyoxyethylene polyoxypropylene block copolymer is 1-3: 1.

the addition of MZxOy, a reducing agent and the like increases the deposition speed and the thickness of a plating layer, but the plating layer is coarse in crystallization, and the tin plating solution can attack the ink on the PCB to loosen the ink, so that the use of the tin plating solution is severely limited due to a series of influences; the applicant has found that the thiourea-like material comprises 2, 3-indoledione 3-thiosemicarbazone, and a first polyoxyethylene polyoxypropylene block copolymer and a second polyoxyethylene polyoxypropylene block copolymer are added; the problem that the tin plating solution attacks the printing ink on the PCB can be well solved; it is presumed that the first polyoxyethylene polyoxypropylene block copolymer and the second polyoxyethylene polyoxypropylene block copolymer adsorb on the surface of the substrate, and the migration of 2, 3-indoledione 3-thiosemicarbazone or the like is hindered by a structure formed by the interaction of the hydrophobic segment and the hydrophilic segment.

As a preferred embodiment, the chemical tin plating solution also comprises 16-20g/L of unsaturated compound containing polar groups; the unsaturated compound containing polar groups comprises at least one of propargyl sodium sulfonate, 5-decyne-4, 7-diol, dimethyl octynediol, butynediol propoxylate and 4-methylpent-2-yne-1, 4-diol; the polar group-containing unsaturated compound comprises sodium propargyl sulfonate and 4-methylpent-2-alkyne-1, 4-diol, wherein the concentration ratio of the sodium propargyl sulfonate to the 4-methylpent-2-alkyne-1, 4-diol is 1: 3-5.

The applicant has also found that the polar group-containing unsaturated compound comprises sodium propargyl sulfonate and 4-methylpent-2-yne-1, 4-diol in a concentration ratio of 1: 3-5, the polyoxyethylene polyoxypropylene block copolymer promotes the tendency adsorption of sodium propargyl sulfonate and 4-methylpent-2-yne-1, 4-diol at the concave and convex parts of the unevenness, so that tin is arranged in the same crystal phase, the glossiness of the tin coating is very good, and the thickness of the coating exceeds 1.0 μm.

The preparation of the chemical tin plating solution is a preparation method commonly used in the field, is not particularly limited, and can be realized by uniformly mixing all the components.

The plating condition of the chemical tin plating solution is 40-45 ℃ and the time is 10-15 min.

The applicant researches the chemical tin plating solution in a meticulous way, and all the components are mutually cooperated to play a role together, so that the deposition rate is high, the thickness of a plating layer is large, and the plating layer is uniform and compact.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

In addition, the starting materials used are all commercially available, unless otherwise specified.