CN103132060A - Anti-corrosion post-treatment liquid for nickel coating surface and treatment process thereof - Google Patents

Abstract

The invention relates to an anti-corrosion post-treatment solution for the surface of a nickel plating layer and a treatment process thereof. The invention includes two parts of aftertreatment liquid and treatment process. The post-treatment liquid is divided into A liquid and B liquid. Liquid A is a water/alcohol mixed solvent containing a silane coupling agent; Liquid B is an emulsion whose main component is long-chain organic fatty acids. The treatment process includes: at room temperature, immerse the nickel coating of the workpiece into solution A, after its surface is formed and reacted with silane, then immersed in solution B heated to a certain temperature for a period of time, finally rinsed with warm water, and dried. After being treated by the invention, a conversion film with good adsorption is formed on the surface of the nickel plating layer, and the corrosion resistance performance is obviously improved, while the appearance and electrical performance of the workpiece are not affected.

Description

A kind of anti-corrosion post-treatment solution and its treatment process for the surface of nickel plating

technical field

The invention relates to an anti-corrosion post-treatment solution for the surface of nickel plating and its treatment process, which belongs to the technical field of metal surface treatment and corrosion protection.

Background technique

Metal nickel or nickel coating is widely used in aviation, automobile, electronics and other industrial fields due to its good performance. However, nickel is prone to corrosion and discoloration in humid air and sulfur-containing industrial atmospheres. The discolored nickel layer not only loses the metallic luster of nickel, but also increases the contact resistance of the nickel surface and reduces the bonding force between nickel and other surface coatings. , causing peeling of the surface coating, while nickel oxides and sulfides will also reduce the welding performance of nickel, so that the phenomenon of virtual welding often occurs.

In recent years, the price of nickel and its salts has continued to rise. Due to cost pressures, many electroplating plants involved in nickel plating have changed the original thick copper thin nickel and multi-layer nickel technology to single-layer thin nickel plating. However, since the thickness of the nickel coating is inversely proportional to the porosity, the porosity of a single layer of thin nickel is relatively high, and its corrosion resistance is inevitably insufficient. In the PCB industry, the thickness of the nickel layer is generally controlled at a few microns. The nickel layer that is prone to corrosion will cause the peeling off of welding equipment, the strength and reliability of wire bonding, and affect the electrical parameters of electronic devices. Therefore, proper post-treatment of the thin nickel layer is required to improve its corrosion resistance. the

At present, the commonly used methods to improve the corrosion resistance of nickel coatings are: chromate passivation treatment. This method has strong anti-corrosion ability and low cost, but chromate is harmful to the environment and human body. Many countries have banned the use of chromate. Make strict restrictions, so manufacturers try not to use chromate passivation process. In addition, a layer of tin or gold can also be plated on the surface of the nickel coating as a protective layer, but this not only increases the process cost, but also changes the characteristics of the nickel surface. the

In order to improve the corrosion resistance of the thin nickel plating layer and at the same time meet the industrial needs of cost saving and environmental protection, the present invention proposes a post-treatment solution for anti-corrosion nickel plating layer and its treatment process. Using this process can make the surface of the nickel plating layer form a A dense organic molecular film can effectively improve its corrosion resistance without affecting the appearance and electrical properties of the workpiece. the

Hu Guanghui's invention patent (application number: 201110101184.7) discloses an electroless nickel plating layer sealing agent and its sealing treatment process. The process uses a mixture of epoxy-containing silane coupling agent and acrylic acid as the sealing agent. After post-treatment of the nickel coating, the obtained organic film has better corrosion resistance, which utilizes the silanol group (Si-OH) generated after the hydrolysis of the epoxy-containing silane coupling agent and the hydroxyl group (-OH) of acrylic acid The acrylic acid-silane coupling agent complex formed by the reaction is used as the main film-forming substance, but the above reaction occupies the active silanol group, which will affect the condensation reaction between the silane coupling agent monomers, resulting in insufficient compactness of the organic film ;Acrylic acid is flammable, explosive, corrosive, and has a strong irritating effect on human skin, eyes and respiratory tract. the

Contents of the invention

Silane coupling agent is a kind of organosilicon compound containing two kinds of functional groups with different chemical properties in the molecule. Its general formula can be represented by YSiX ₃ , Y is a non-hydrolyzable group, and the functional group in Y can react with the functional group in organic matter. X is a hydrolyzable group, which generates Si-OH after hydrolysis, and can form Si-O-Me (Me represents metal) chemical bond with metal. Therefore, the silane coupling agent can play a coupling role between the organic matter and the metal surface, and enhance the binding ability between the organic fatty acid and the organic fatty acid-silane coupling agent and the nickel coating.

The purpose of the present invention is to solve the problem of insufficient corrosion resistance of thin nickel coatings in the prior art, and proposes a post-treatment solution and its treatment process that can significantly improve the corrosion resistance of nickel coatings. The present invention utilizes silane coupling agent Pretreat the nickel coating to form a layer of silane film with good adhesion on the surface, and then immerse the long-chain organic fatty acid emulsion to make the silane coupling agent adsorbed on the surface of the nickel coating react with the long-chain organic fatty acid , A dense mixed film is formed on the surface of the nickel coating. This layer of film has strong hydrophobicity and corrosion resistance, which can significantly improve the corrosion resistance of the nickel coating without affecting the appearance and electrical properties of the workpiece. the

The present invention is a kind of anti-corrosion post-treatment solution for the surface of the nickel coating and its treatment process. The technical scheme includes two parts: the preparation and the treatment process of the anti-corrosion post-treatment solution for the nickel coating:

 镍镀层防腐蚀后处理液由A液和B液组成，按以下方法配制：

The post-treatment liquid for anti-corrosion of nickel plating is composed of liquid A and liquid B, prepared according to the following method:

Slowly add the amino group-containing silane coupling agent into the water/alcohol mixed solvent with a volume ratio of 1/98~1/8, and stop adding when the mole fraction of the amino group-containing silane coupling agent reaches 0.1~0.5mol/L , hydrolyzed for a period of time at room temperature to obtain liquid A.

Add quantitative long-chain saturated fatty acid or long-chain unsaturated fatty acid into water dissolved with anionic or nonionic surfactant, control the concentration of fatty acid to 1-10mmol/L, adjust the pH of the solution to 2-3 with acid, and obtain Liquid B. the

 处理工艺：室温下，将工件镍镀层浸入A液10～60秒后取出，再浸入温度为50～70℃的B液15～30分钟后取出，用温水冲洗，最后吹干工件镍镀层表面即可。 

Treatment process: at room temperature, immerse the nickel coating of the workpiece in solution A for 10 to 60 seconds, then take it out, then immerse it in solution B at a temperature of 50 to 70°C for 15 to 30 minutes, take it out, rinse with warm water, and finally dry the surface of the nickel coating on the workpiece. Can.

The amino group-containing silane coupling agent is any of γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, polyaminoalkyltrialkoxysilane A sort of. the

Alcohols are either isopropanol or butanol. the

Long-chain saturated fatty acid or long-chain unsaturated fatty acid is any one of lauric acid, stearic acid, palmitic acid, and oleic acid. the

The surfactant is any one of sodium dodecylsulfonate and polyethylene glycol octyl ether. the

The acid is either phosphoric acid or acetic acid. the

the

Technical effect of the present invention:

Compared with the prior art, the present invention has unshared electron pairs in the amino group-containing silane coupling agent, which can be combined with protons to be alkaline, so the silane coupling agent adsorbed on the surface of the nickel coating can pass the active group The reaction between the group amino group and the long-chain fatty acid carboxyl group forms a complex, which increases the thickness of the silane organic film, and the long-chain organic fatty acid itself has a strong coordination ability with nickel, and the oxygen atom in the carboxyl group reacts with the surface of the nickel coating. The formation of fatty acid complexes can form an adsorption film in the pores of the organic fatty acid-silane coupling agent complex film, increase the compactness of the organic fatty acid-silane coupling agent complex film, improve its hydrophobicity and isolate the corrosive medium ability, so that the organic fatty acid-silane coupling agent complex film has stronger corrosion inhibition performance. In addition, the cost of raw materials used in the anti-corrosion post-treatment liquid is low, non-toxic and environmentally friendly, and the treatment process is simple and efficient.

After being treated with the anti-corrosion post-treatment solution of the invention, the corrosion resistance of the nickel coating is significantly improved, the appearance of the workpiece remains unchanged, and the electrical performance is stable. the

the

Detailed ways

The steel plate is cut into experimental plates according to the specification of 5cm×2cm, and after chemical degreasing, rust removal, and activation, electroless nickel plating is performed. The thickness of the nickel plating layer is about 4 μm. After nickel plating, the post-treatment solution of the present invention is used for treatment. the

Example 1

1. Preparation of liquid A: slowly add 0.5mol γ-aminopropyltrimethoxysilane into 1 liter of water/butanol mixed solvent, the water/alcohol volume ratio is 1:17, and hydrolyze for a period of time at room temperature;

2. Preparation of liquid B: Dissolve 1 mmol of stearic acid in 1 L of water with sodium dodecyl sulfate, and adjust the pH of the solution to 2 with phosphoric acid;

3. At room temperature, immerse the test board in liquid A for 30 seconds, take it out, immerse it in liquid B for 15 minutes, the temperature of liquid B is 70°C, take it out, rinse it with warm water, dry it, and test the corrosion resistance and electrical properties.

Example 2

1. Preparation of liquid A: Slowly add 0.2mol N-β(aminoethyl)-γ-aminopropyltriethoxysilane to 1 liter of water/isopropanol mixed solvent, the water/alcohol volume ratio is 2:17 , hydrolyzed for a period of time at room temperature;

2. Preparation of liquid B: Dissolve 5mmol stearic acid in 1L water with polyethylene glycol octyl ether, adjust the pH of the solution with phosphoric acid

adjust to 3;

3. At room temperature, immerse the test board in liquid A for 60 seconds, take it out, and immerse it in liquid B for 20 minutes. The temperature of liquid B is 60°C.

After washing with warm water, blow dry, and test the corrosion resistance and electrical properties.

Example 3

1. Preparation of liquid A: Slowly add 0.1 mol of polyaminoalkyltrialkoxysilane into 1 liter of water/butanol mixed solvent, the water/alcohol volume ratio is 1:11, and hydrolyze for a period of time at room temperature;

2. Preparation of liquid B: Dissolve 10 mmol of stearic acid in 1 L of water with sodium dodecyl sulfate, and adjust the pH of the solution to 2.5 with acetic acid;

3. At room temperature, immerse the test board in solution A for 45 seconds, take it out, immerse it in solution B for 30 minutes, the temperature of solution B is 50°C, take it out, rinse it with warm water, dry it, and test the corrosion resistance and electrical properties.

the

The relevant test data of the above-mentioned embodiment samples are as follows:

1. Neutral salt spray test experiment

After the nickel-plated experimental plate was processed according to the processes of Example 1, Example 2, and Example 3, the neutral salt spray test was carried out after 24 hours, and the results are shown in Table 1

Table 1. Experimental data table of neutral salt spray test

2. Weldability experiment

After the nickel-plated experimental boards were processed according to the processes of Example 1, Example 2, and Example 3, the experimental boards were baked in a secondary reflow oven, and the center positions of the experimental boards were respectively placed during the third reflow. Place a SnCu, SnAg, SnAgCu solder ring with a wire diameter of 1.5mm. The diameter of the ring is about 3mm. Drop 0.5mL of solder resist into the center of the ring for reflow soldering. Test the spreading rate of solder on each experimental board, the results are shown in Table 2

Table 2. Experimental data table for compatibility between experimental board and solder

The above data show that: the experimental board after the present invention has passed the relevant corrosion test, which shows that the corrosion resistance of the nickel coating is greatly improved; and the experimental board still has good compatibility with solder resist and solder after three reflows. The welding reliability is high, and it can fully meet the relevant process requirements of nickel plating.

the

Claims (6)

1. protection against corrosion aftertreatment fluid and treatment process thereof that is used for the nickel coating surface comprises it is characterized in that preparation and treatment process two portions of nickel coating protection against corrosion aftertreatment fluid:

Described nickel coating protection against corrosion aftertreatment fluid is comprised of A liquid and B liquid, by the following method preparation:

To contain amino silane coupling agent, slowly to add volume ratio be in 1/98～1/8 water/alcohols mixed solvent, when containing amino silane coupling agent molar fraction and reach 0.1～0.5mol/L, stops adding, and is hydrolyzed for some time under room temperature, makes A liquid;

Quantitative chain saturated fatty acids or long-chain unsaturated fatty acid are joined in the water that is dissolved with tensio-active agent, and fatty acid concentration is controlled to be 1～10mmol/L, with acid, pH value of solution is adjusted to 2～3, makes B liquid;

Described treatment process: under room temperature, the workpiece nickel coating is immersed A liquid, and to take out, then immerse afterwards temperature in 10～60 seconds be that the B liquid of 50～70 ℃ took out after 15～30 minutes, uses warm water washing, dries up at last that the workpiece nickel coating is surperficial to be got final product.

2. a kind of protection against corrosion aftertreatment fluid and treatment process thereof for the nickel coating surface according to claim 1 is characterized in that: described to contain amino silane coupling agent be any one in γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyl triethoxysilane, polyamino alkyltrialkoxysilaneand.

3. a kind of protection against corrosion aftertreatment fluid and treatment process thereof for the nickel coating surface according to claim 1, it is characterized in that: described alcohols is any one in Virahol, butanols.

4. a kind of protection against corrosion aftertreatment fluid and treatment process thereof for the nickel coating surface according to claim 1, it is characterized in that: described chain saturated fatty acids or long-chain unsaturated fatty acid are any one in laurostearic acid, stearic acid, palmitinic acid, oleic acid.

5. a kind of protection against corrosion aftertreatment fluid and treatment process thereof for the nickel coating surface according to claim 1, it is characterized in that: described tensio-active agent is any one in sodium laurylsulfonate, polyoxyethylene glycol Octyl Ether.

6. a kind of protection against corrosion aftertreatment fluid and treatment process thereof for the nickel coating surface according to claim 1 is characterized in that: the acid of described adjusting pH is any one in phosphoric acid, acetic acid.