CN108396325B

CN108396325B - Water-soluble weldable nickel protective agent

Info

Publication number: CN108396325B
Application number: CN201810161376.9A
Authority: CN
Inventors: 吴小明; 刘宏; 伍继柱; 王朝霞; 刘倩源
Original assignee: TANTZ ENVIRONMENTAL TECHNOLOGIES Ltd
Current assignee: TANTZ ENVIRONMENTAL TECHNOLOGIES Ltd
Priority date: 2018-02-27
Filing date: 2018-02-27
Publication date: 2020-07-03
Anticipated expiration: 2038-02-27
Also published as: CN108396325A

Abstract

The invention discloses a water-soluble weldable nickel protective agent. The water-soluble weldable nickel protective agent contains fatty alcohol and quinoline carboxylic acid, wherein the molar ratio of the fatty alcohol to the quinoline carboxylic acid is 1: 1-3: 1. The invention adopts the combination of fatty alcohol and quinoline carboxylic acid as the protective agent of weldable nickel for the first time, on one hand, quinoline carboxylic acid can strip the oxidation film layer of nickel, on the other hand, quinoline carboxylic acid and fatty alcohol generate esterification reaction to complex on the surface of the nickel layer to form a compact protective film to block the oxidation of nickel, and meanwhile, the protective film can reduce nickel oxide into simple substance nickel to accelerate the stripping of the oxidation film layer. The protective agent integrates corrosion inhibition, corrosion prevention and reduction soldering assistance, realizes synchronous treatment of stripping an oxidation film and shielding a reductive protective film, has no hidden danger of residual corrosion, really avoids water washing, automatically decomposes the protective film during soldering, and ensures smooth soldering.

Description

Water-soluble weldable nickel protective agent

Technical Field

The invention belongs to the technical field of surface treatment of electronic components, and particularly relates to a water-soluble weldable nickel protective agent.

Background

With the market demand for portability and multi-functionalization of electronic products, the packaging technology and circuit board (PCB) must be continuously increased in density. Because the bonding pad of the PCB is made of copper, an oxide layer is easily formed on the surface of the copper, the resistance is high, even the insulation is high, and the welding cannot be carried out. Therefore, a topcoat (plating) layer must be applied/plated over the copper pads of the PCB for protection.

In electronic products, nickel plating is a commonly used metal plating. The weldable nickel coating is adopted on the electronic element, and has the following functions: providing a solderable top layer on a non-solderable substrate; a barrier layer for preventing the base material from penetrating into the molten tin-lead solder; the formation of an intermetallic compound composed of an unnecessary base alloy and a surface finish metal is suppressed. However, due to the extremely easy and rapid self-passivation property of the nickel coating, the nickel coating starts to self-passivate in air for a few seconds to generate a compact oxide film, so that the nickel-plated element has poor weldability, insufficient welding, sagging and other phenomena, thereby causing the resistance of a welding part to be increased or short-circuited, and seriously affecting the use of electronic products.

At present, the industry mainly improves the weldability of nickel plating layers by the following processes:

1 improved bath composition

When electroless nickel is plated, the phosphorus content of the plating can affect the solderability of the nickel plating. The low-phosphorus nickel plating layer has better weldability, and the medium-high phosphorus nickel plating layer has poorer weldability. However, with low phosphorous nickel coatings, the phosphorous content of the coating gradually increases over time and the solderability deteriorates. The invention of patent No. 201010603610.2 provides a high solderability electroless nickel-phosphorus alloy plating solution, which makes the electroless nickel-phosphorus plating layer have better solderability and is not limited by the phosphorus content in the plating layer.

2 coating a metal protective layer on the surface

The surface coating protective layer is mainly made of inert metal, such as gold and palladium, and used for covering and protecting a fresh nickel surface to prevent the nickel coating from being oxidized, so that the good weldability of the nickel coating is ensured.

The Electroless Nickel/Immersion Gold process (ENIG) has been rapidly popularized both at home and abroad since 1996. In order to improve the solderability of the chemical nickel coating, a gold coating is deposited on the surface of the nickel coating by a displacement precipitation method. However, gold is expensive, can dissolve automatically in the brazing process, and is damaged when reaching a certain concentration; and because the nickel plating layer has the problems of porous crystal structure (related to phosphorus content, roughness and the like), large internal stress, large brittleness and the like, and the phosphorus-rich layer is positioned between the nickel layer and the gold (thin) layer and is easy to corrode and crack, and the like, the possibility of generating a black disc by the chemical nickel plating layer is increased.

Electroless Nickel/Electroless palladium/immersion Gold (ENEPIG) appeared in the 70 s of the 20 th century, but it was not promoted because of the low demand for PCB density and high cost. Currently, with the requirement of high density of PCBs, the ENEPIG technology is gaining attention. Although the black disc phenomenon cannot occur in ENEPIG, palladium and gold are precious metals, and the pressure of the production cost is not small.

Chinese patent No. 200580023897.9 discloses an improvement in solderability of nickel coatings by depositing a thin layer of palladium on the nickel coating by cementation in an acidic palladium solution. The palladium salt required by the method has no special requirements, and the acid can be sulfuric acid, phosphoric acid, palladium hydrofluoric acid, acetic acid and oxalic acid, and is convenient to purchase. And the palladium plating layer deposited on the surface of the nickel plating layer by a replacement method is extremely thin and 0.008-0.016 mu m, and the performance of nickel is not influenced. The method has simple process, is simultaneously suitable for plating matt nickel and chemical nickel plating, but improves the production cost and increases the production pressure.

There is also a problem of poor solderability solved by depositing tin or tin alloy on the surface of nickel. However, by covering the surface with the coating, wherein the thickness of the deposited layer is in the range of 2-5 μm, some of the advantageous properties of nickel (e.g. hardness, wear resistance, bondability) are affected. And the method is only suitable for electroplating nickel, and cannot realize the metal patterns on the surface of the plating layer.

3 post-plating treatment

Su He and Lin Zhang have developed a nickel coating passivator MP, the main components of which are-N-, -S-, -P-organic compounds containing lone pair electrons such as triazole and a little additive H. It should be noted that the anti-passivant must be used in a state where the nickel is active to be effective. Before passivation, a nickel-plated layer is required to be subjected to fine polishing to remove an oxide layer on the surface, then the nickel-plated PCB is put into MP water solution for dip-coating for a certain time, and then the PCB is washed by tap water and then is washed by deionized water after the dip-coating. The dip coating time must be strictly controlled and is detrimental to the solder.

The process permanent red adds Solder additive in nickel plating solution to improve weldability, and further uses CYH-W protective agent for post treatment. CYH-W is used as a water-soluble antioxidant, and a micro molecular film can be formed on the surface of the plating layer by dip coating, so that the plating layer is prevented from contacting with air. The synergistic use of the Solder additive and the CYH-W antioxidant can maintain the weldability of the product for a long time. However, the CYH-W only having the anti-oxidation function is only suitable for the surface of a fresh nickel layer, and the anode of the weldable bright nickel plating process can only use electrolytic nickel and cannot use high-sulfur nickel.

The invention patent of patent No. 200880020640.1 discloses a solution and method for improving solderability and corrosion resistance of metal or metal alloy surfaces, particularly tin and its alloy surfaces, comprising a solution of a phosphorus compound and a solderability-enhancing compound. However, when applied to metallic nickel, the enrichment of the phosphorus-based film on the surface of the nickel layer poses a potential problem for its solderability.

In practical application, due to the rapid self-passivation property of nickel, the prior art does not allow the industry to solder the nickel coating for a long time, but solder the fresh nickel surface immediately after performing the solderability treatment. The most common practice in the industry is to remove the nickel coating oxide layer by dilute hydrochloric acid, dilute nitric acid etching or electrochemical etching, then wash with pure water for 2-3 times, and then solder. The method needs to remove an oxide film and carry out multiple washing residues in steps, and has the disadvantages of no need for removing the oxide film, complicated process and cumbersome process; the nickel surface is not protected against passivation and oxidation, the treated nickel surface needs to be immediately soldered, and the solderability of long-time storage cannot be guaranteed; in addition, acid radicals of hydrochloric acid and nitric acid are strong acid radical ions, which are easy to remain and cause further corrosion to a nickel layer, thus influencing weldability, and during washing, if the remaining acid radical ions enter the interior of the nickel plating layer micropores along with water, serious electrochemical corrosion is caused. For a nickel surface which is placed for a long time, because the nickel oxide film layer is too thick, the time for stripping an oxidation film by strong acid treatment is longer, the corrosion hidden danger is more, and the method cannot be used in the industry.

Disclosure of Invention

In order to solve the problems of poor weldability, limitation of traditional dilute acid soaking to a fresh nickel surface, complex process, easy residual corrosion of acid radical ions and the like caused by self-passivation of a nickel coating, the invention provides the water-soluble weldable nickel protective agent. During soldering, the film layer can be automatically decomposed at the high temperature (245-260 ℃) of the soldering tin, and smooth proceeding of the soldering tin is ensured.

The above object of the present invention is achieved by the following technical means.

In one aspect, the invention provides a water soluble weldable nickel protectant comprising an aliphatic alcohol and a quinoline carboxylic acid.

Quinoline carboxylic acid is an important pesticide, medicine and medicine intermediate, can be used for synthesizing imidazolone herbicides containing quinoline rings, and can also be used for synthesizing antibiotics and important medicine intermediates. Many drugs containing quinoline rings have various biological activities such as anti-tumor, antibacterial, anti-inflammatory, memory enhancing, anti-depression and anti-hypertension.

The invention firstly makes quinoline carboxylic acid and fatty alcohol jointly act on the field of solderability protection of nickel coatings. On one hand, the weak acid radical ions of the quinoline carboxylic acid are utilized to strip the oxidation film layer of the nickel, on the other hand, after the quinoline carboxylic acid and the fatty alcohol are subjected to esterification reaction, a compact semi-hard dry protective film is formed on the surface of the nickel layer in a complexing mode, a corrosion medium is isolated, and the oxidation of the nickel is blocked. Meanwhile, the protective film layer has reducibility, can reduce nickel oxide into simple substance nickel, further accelerates the stripping of the oxide film layer, and more comprehensively protects the weldability of nickel. During soldering, the film layer can be automatically decomposed at the high temperature (245-260 ℃) of the soldering tin, and smooth proceeding of the soldering tin is ensured.

The quinoline carboxylic acid adopted by the invention is quinoline formic acid or quinoline acetic acid or a mixture of the two. Preferably one or more of quinoline-2-carboxylic acid, 2-quinoline-acetic acid, quinoline-3-carboxylic acid, 3-quinoline-acetic acid, quinoline-4-carboxylic acid and 4-quinoline-acetic acid. More preferably one or a mixture of more of quinoline-2-carboxylic acid, quinoline-3-carboxylic acid and quinoline-4-carboxylic acid. Most preferred is quinoline-2-carboxylic acid.

The fatty alcohol adopted by the invention has a structural formula of C_nH_2n+1-fatty alcohols of OH. The length of the straight-chain fatty alcohol is the largest when the number of carbon atoms is the same, and the thickness of the formed hydrophobic film is relatively the highest; the performance of the film density of the film layer can have defects due to the influence of the spatial structure when the branched fatty alcohol is used for forming the film. However, the larger the carbon number of the linear fatty alcohol is, the longer the length is, and the thicker the thickness of the hydrophobic film is, the better the protective fluxing property can be. Apparently, the inventor of the present invention finds, through repeated tests, that during the process of increasing the number of carbon atoms of the straight-chain fatty alcohol from 6 to 22, the fluxing performance of the protective agent shows a trend of first being remarkably increased and then being slowly reduced. When the number of carbon atoms is increased from 6 to 18, the thickness of the film layer is gradually increased, and the fluxing capacity of the protective agent system is improved; when the number of carbon atoms is increased from 18 to 22, the steric hindrance effect of the film forming effect is increased, the binding force of the film forming substance and the metal surface is weakened, and the fluxing performance of the protective agent is slightly reduced. Therefore, the aliphatic alcohol according to the present invention is preferably a linear aliphatic alcohol having 8 to 20 carbon atoms, and more preferably a linear aliphatic alcohol having 12 to 18 carbon atoms. As an embodiment of the present invention, optional (but not limited) straight-chain fatty alcohols include: 1-octanol (octaol), n-decanol (decaol), lauryl alcohol (dodecanol), tridecanol, tetradecanol, cetyl alcohol, heptadecanol, stearyl alcohol (octadecanol), eicosanol, and the like.

The molar ratio of the aliphatic alcohol to the quinoline carboxylic acid is 1: 1-3: 1. Repeated experiments show that when the molar ratio of the water-soluble weldable nickel protective agent to the protective agent is lower than 1:1, the hydrophilicity of the whole water-soluble weldable nickel protective agent system is too strong and the hydrophobicity is not enough, the thickness and the compactness of a surface film layer are reduced, and the welding assisting function of the protective agent is reduced; when the molar ratio of the two is more than 3:1, the water solubility of the whole system is poor, the steric hindrance of the formed molecular structure is large, the film forming effect is difficult, the bonding force between film forming molecules and a metal plating layer is weakened, the surface film layer is difficult to achieve the complete and compact degree, and the welding-assistant function is reduced. When the molar ratio of the fatty alcohol to the quinoline carboxylic acid is 2:1, the film-forming binding force, the compactness and the hydrophilic hydrophobicity of the film are well considered, and the fluxing performance of the protective agent is optimal. Thus, it is finally preferred that the molar ratio of fatty alcohol to quinoline carboxylic acid is 2: 1.

As a further preferred embodiment, the water-soluble solderable nickel protectant of the present invention further comprises a corrosion inhibitor, a complex surfactant system, a chelating agent, and a builder.

The corrosion inhibitor is composed of one or more compounds of azole compounds, imidazole compounds, sulfydryl compounds, thiazole compounds, long-chain aromatic hydrocarbon sulfonic acid and salts thereof and the like.

The composite surfactant system contains one or more than one hydrocarbon surfactant and at least contains one or more than one of fluorine surfactant and biosurfactant; wherein the fluorosurfactant is one or more of nonionic and anionic; the biosurfactant is one or more of rhamnolipid, sophorolipid and polysaccharide, preferably rhamnolipid. And the most preferred surfactant system is a complex surfactant system containing both hydrocarbon surfactant, biosurfactant and fluorosurfactant.

The chelating agent is an alcamines organic matter, preferably diethanolamine and triethanolamine.

The builder comprises a heterocyclic alcohol, an alcohol ether, or a mixture of both. The heterocyclic alcohol is preferably tetrahydrofurfuryl alcohol; the alcohol ether is preferably at least one of ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, propylene glycol monobutyl ether, propylene glycol dibutyl ether and the like.

In addition to the above components, the components of the present invention further comprise water, and the weight parts of the water can be adjusted according to different situations, such as the convenience of transportation and storage when preparing the product, and at this time, no water or a small amount of water can be added to increase the concentration of the fatty alcohol and the quinoline carboxylic acid; when in use, the water can be added for dilution, and the proper use concentration is adjusted. Of course, the use of the same or similar concentrations for transportation, storage and use is not excluded.

In a preferred embodiment of the present invention, when the water-soluble weldable nickel protecting agent is used, the concentration of the aliphatic alcohol and the quinoline carboxylic acid is 0.3 to 1.4% (by mass). In a preferred embodiment, the concentration of the aliphatic alcohol and quinoline carboxylic acid in the water-soluble weldable nickel protectant of the invention during transportation and storage is 10% to 20% (mass concentration). In a preferred embodiment, the pore sealing agent concentrate is free of water, but it is diluted to the use concentration when used, and there is a possibility that the concentrate concentration becomes too high to cause a poor appearance.

In a preferred embodiment, the water-soluble weldable nickel protective agent provided by the invention comprises the following components in parts by weight: 10-15 parts of fatty alcohol and quinoline carboxylic acid, 4-10 parts of corrosion inhibitor, 10-20 parts of composite surfactant system, 15-25 parts of chelating agent and 10-20 parts of builder. The specific constituents of the auxiliaries are as described above. When in use, the water is firstly diluted to 3 to 7 percent (mass ratio) by pure water, and the suggested concentration is 5 percent (mass ratio).

It should be noted that various corrosion inhibitors, surfactants, chelating agents, and builders commonly used can be used in the present invention to prepare the water soluble solderable nickel protectant without affecting or contributing to the rapid stripping of the nickel oxide layer while producing a reducing protective film. The core point of the invention is to provide a water-soluble weldable nickel protective agent, which can rapidly strip the nickel oxide layer and simultaneously generate a reducing protective film to shield a corrosion medium, has no residual corrosion hidden trouble, is free from water washing, and finally improves the weldability of the nickel plating layer of the electronic component. This object is achieved by the fatty alcohols and the quinoline carboxylic acids as the main functional components; the corrosion inhibitor, the hydrocarbon surfactant, the chelating agent, the builder and the like have the functions of assisting main functional components, implementing high-efficiency cleaning on the surface of the metal coating and the micropore and deformed crystal defects of the coating, initially reducing the metal corrosion activity of the coating and the like so as to enhance the comprehensive protection performance after the fatty alcohol and the quinoline carboxylic acid react to form a film. Therefore, although the present invention lists preferred corrosion inhibitors, surfactants, chelating agents, builders, etc., the corrosion inhibitors, surfactants, chelating agents, builders, etc., which can be used in the present invention, are not limited to the above-mentioned species, as long as they are auxiliary agents which do not affect or contribute to the rapid stripping of the nickel oxide layer while forming a reductive protective film in the prior art.

In another aspect, the invention also provides a use method of the weldable nickel protectant: a simple soaking process is adopted. Specifically, a nickel-plated component is soaked in a weldable nickel protective agent for treatment at the temperature of 50-55 ℃ for 5-90 seconds, and then taken out for drying by hot air. Because of the extremely easy rapid self-passivation property of the nickel coating, the fresh nickel coating can begin to generate a compact oxide film by self-passivation after being exposed in the air for 1-2 seconds. After a period of time, considering the nickel surface oxide film layer is too thick, a cathodic electrolysis assisted soaking process is preferred to accelerate the stripping or reduction of the nickel oxide film layer by the invention, namely: the workpiece is used as a cathode, the stainless steel is used as an anode, and the voltage is controlled to be 5-8V.

The invention has the beneficial effects that:

1. the invention integrates corrosion inhibition and corrosion prevention with reduction and soldering assistance through a simple soaking process, realizes the synchronous treatment of stripping an oxidation film and shielding a reductive protective film, has no hidden danger of residual corrosion, really avoids water washing, automatically decomposes the protective film during soldering, and ensures the smooth operation of soldering.

2. The invention is suitable for any fresh or long-standing nickel plating layer obtained by electroplating and chemical plating processes, and the nickel plating layer is dipped in tin for 5s at 255 ℃ after being treated by the invention, the tin-coating area is more than 95%, and the solderability is good.

3. The salt spray resistance of the nickel-plated layer of the iron material treated by the invention is 8-12 hours, and the salt spray resistance of the nickel-plated layer of the copper material is 48-72 hours, which both meet the standard commonly used in the industry.

4. The nickel coating treated by the invention is exposed in the air for half a year, and the weldability is still good.

Drawings

FIG. 1 is a drawing showing the immersion tin picture of the treated nickel coating, and it can be seen that the solderable nickel protectant of the present invention has the advantages of full tin climbing, complete coverage, no nickel exposure and tin leakage, and good solderability.

Detailed Description

The technical solutions of the present invention are further illustrated by the following specific examples, which do not represent limitations to the scope of the present invention. Insubstantial modifications and adaptations of the present invention by others of the concepts fall within the scope of the invention.

EXAMPLE 1 weldable Nickel protectant

TABLE 1

TABLE 2

The working solutions were prepared by preparing concentrates according to 8 formulations in tables 1 and 2, respectively, and diluting the concentrates to a concentration of 5% with pure water.

Example 2 solder Performance testing

The purpose is as follows: the soldering tin performance of the fresh and long-standing nickel plating layer after being treated by different formulas is tested by utilizing a simple tin immersion method commonly used in the industry.

Testing a workpiece sample:

sample 1: fresh nickel face. Copper material nickel plating welding leg, electroplating process, nickel layer film thickness 1.0-2 μm (40-80 μm).

Sample 2: placing the nickel surface for a long time. Copper material nickel plating welding leg, electroplating process, nickel layer film thickness 1.0-2 μm (40-80 μm). Open in air for 3 months.

Solderability protection treatment conditions:

heating 8 formula working solutions in example 1 to 50 ℃, directly soaking the fresh nickel surface in the 8 formula working solutions for treatment for 5 seconds, taking out the fresh nickel surface and drying the fresh nickel surface by hot air; the nickel surface is placed for a long time by adopting a cathode electrolysis auxiliary process, a workpiece is taken as a cathode, stainless steel is taken as an anode, the voltage is controlled to be 7V, the nickel surface is soaked in 8 formula working solutions for treatment for 30 seconds, and the nickel surface is taken out and dried by hot air.

Simple tin immersion test: after the workpiece is treated, the workpiece is dipped in tin for 5 seconds at 255 ℃, and the phenomena of tin leakage and nickel exposure are not observed by naked eyes, namely the tin-coating area is more than or equal to 95 percent, and the tin soldering property is qualified.

And (3) testing results: after 8 formula treatments, the tin coating area of the fresh nickel surface and the long-term nickel surface is more than or equal to 95 percent, and the solderability is good.

Example 3 Corrosion resistance test of Nickel coating

The purpose is as follows: and testing the corrosion resistance and oxidation resistance of the nickel coating after being treated by different formulas by using a neutral salt spray test.

Testing a workpiece sample:

sample 1: the copper base material is chemically plated with nickel, and the thickness of the nickel layer is 2 mu m (80 mu).

Sample 2: the ferrite material was plated with nickel, and the nickel layer was 2.5 μm (100 μm) thick.

Solderability protection treatment conditions: 8 working solutions of the formula in example 1 were heated to 55 ℃, both sample 1 and sample 2 were soaked for 10 seconds, and then taken out and dried with hot air.

A blank control group was also set, i.e., no solderability preservation treatment was performed.

A test workpiece sample is subjected to neutral salt spray test after being treated by the method, and the specific test method refers to the test standard GB/T10125-2012 'Artificial atmosphere Corrosion test-salt spray test'. The requirement of the industry on the salt spray corrosion resistance of the nickel coating varies with the base material, and the salt spray resistance of the copper base material nickel plating is generally required to be 24-48 hours; the nickel plating of the iron base material is generally required to be resistant to salt spray for 8 hours because iron is more active than copper. The salt spray test cycle for this test is based on standards commonly used in the industry and is detailed in table 3. The test results were evaluated according to GB/T6461-2002 rating Standard of samples and test pieces after corrosion tests of metals and other inorganic coatings on Metal substrates. The appearance and cover layer failure rating results are shown in tables 4 and 5.

TABLE 3 neutral salt spray test periods for different formulations and samples

Numbering	1. 2, 3 and 4 formula	5. 6, 7 and 8 formula
			Sample 1 copper material nickel plating	48h	72h
Sample 2 iron material nickel plating	8h	12h

TABLE 4 comparison of neutral salt spray tests for formulations 1-4

Numbering	Description of the samples	Appearance rating	Coating failure rating
				Sample 1	Copper material nickel plating, blank, salt spray 48h	Level 1	Class H
Sample 1	Copper material is plated with nickel, weldability is protected, salt spray is 48h	Grade 10	Class A
				Sample 2	Nickel plating, blank and salt spraying for 8h	Level 1	Class H
Sample 2	Nickel plating of iron material, weldability protection, salt spray 8h	Grade 10	Class A

TABLE 5 comparison of neutral salt spray tests for formulations 5-8

Numbering	Description of the samples	Appearance rating	Coating failure rating
				Sample 1	Copper material nickel plating, blank, salt spray 72h	Level 1	Class H
Sample 1	Copper material is plated with nickel, weldability is protected, salt spray is carried out for 72h	Grade 10	Class A
				Sample 2	Nickel plating, blank and salt spraying for 12h	Level 1	Class H
Sample 2	Nickel plating of iron material, weldability protection, salt spray 12h	Grade 10	Class A

Note: the appearance of the A-level surface is unchanged; corrosion cracking of the H-level plating layer.

To summarize: as can be seen from tables 4 and 5, the samples treated by the weldable nickel protectant of the present invention have no change in the appearance of the plating layer and no corrosion defects after the salt spray test, and can maintain the 10-grade appearance rating and the A-grade coating damage rating; after the samples which are not treated by the weldability protection are subjected to the salt spray test, the coating is corroded in a large area, and cracks appear. The weldable nickel protectant (formulations 1-4) containing only fatty alcohol and quinoline carboxylic acid has fully satisfied the industry's salt spray resistance requirements for nickel coatings; the samples treated with the weldable nickel protectant (formulations 5-8) with other additives also exhibited longer corrosion resistance after salt spray corrosion than the weldable nickel protectant (formulations 1-4) with only the fatty alcohol and the quinoline carboxylic acid. The other auxiliary agents have certain performance improving effects.

Example 4 storage solderability testing

The purpose is as follows: the invention was tested for its ability to protect the solderability of the nickel plating layer for a long period of time.

Testing a workpiece sample:

fresh nickel face. The copper material is plated with nickel solder leg, and the thickness of the nickel plating layer is 1.0-2 μm (40-80 μm).

Solderability protection treatment conditions: 8 working solutions of the formula in example 1 were heated to 55 ℃, samples were soaked for 80 seconds, and then taken out and dried with hot air.

The samples treated with formulations 1, 2, 3 and 4 were left open in the room for 2 months (average temperature 25 ℃ C., relative humidity RH 60%) and tested for solderability in the same manner as in example 2.

The samples treated with formulations 5, 6, 7 and 8 were left open in the room for 6 months (average temperature 25 ℃ C., relative humidity RH 60%) and tested for solderability in the same manner as in example 2.

The result shows that after the treated sample is placed for 2-6 months for a long time, the surface of the nickel coating has no obvious corrosion and oxidation phenomena, the wetting area of the immersion tin test reaches more than 95%, and the sample still has good weldability.

Claims

1. The composition is characterized by comprising fatty alcohol and quinoline carboxylic acid, wherein the molar ratio of the fatty alcohol to the quinoline carboxylic acid is 1: 1-3: 1;

the composition acts as a water soluble solderable nickel protectant;

the composition further comprises a corrosion inhibitor, a complex surfactant system, a chelating agent, and a builder; the composition comprises the following components in parts by weight:

10-15 parts of fatty alcohol and quinoline carboxylic acid;

4-10 parts of a corrosion inhibitor;

10-20 parts of a composite surfactant system;

15-25 parts of a chelating agent;

10-20 parts of a builder.

2. The composition of claim 1, wherein the fatty alcohol is of formula C_nH_2n+1-fatty alcohols of OH.

3. Composition according to claim 2, characterized in that the fatty alcohol C_nH_2n+1OH is straight-chain fatty alcohol with the C atom number n between 8 and 20.

4. Set according to claim 2The compound is characterized in that the fatty alcohol C_nH_2n+1OH is straight-chain fatty alcohol with the C atom number n between 12 and 18.

5. The composition of claim 1, wherein the quinoline carboxylic acid is quinoline carboxylic acid or quinoline acetic acid or a mixture of both.

6. The composition according to claim 1, wherein the quinoline carboxylic acid is one or more of quinoline-2-carboxylic acid, 2-quinoline-acetic acid, quinoline-3-carboxylic acid, 3-quinoline-acetic acid, quinoline-4-carboxylic acid, and 4-quinoline-acetic acid.

7. The composition of claim 1, wherein the molar ratio of fatty alcohol to quinoline carboxylic acid is 2: 1.

8. The composition of claim 1, wherein: the corrosion inhibitor is composed of one or more compounds of azole compounds, imidazole compounds, sulfydryl compounds, thiazole compounds and long-chain aromatic hydrocarbon sulfonic acid or salts thereof.

9. The composition of claim 1, wherein the complex surfactant system comprises at least one hydrocarbon surfactant and at least one of a fluorosurfactant and a biosurfactant.

10. The composition of claim 9 wherein said fluorosurfactant is one or more of nonionic and anionic.

11. The composition of claim 9, wherein the biosurfactant is one or more of rhamnolipids, sophorolipids and polysaccharides.

12. The composition of claim 1 wherein said surfactant system comprises a combination of a hydrocarbon surfactant, a biosurfactant and a fluorosurfactant.

13. The composition of claim 1, wherein the chelating agent is an organic alkanolamine.

14. The composition of claim 13, wherein the organic alkanolamine is diethanolamine and/or triethanolamine.

15. The composition of claim 1, wherein the builder is a heterocyclic alcohol and/or an alcohol ether.

16. The composition of claim 15 wherein said heterocyclic alcohol is tetrahydrofurfuryl alcohol.

17. The composition according to claim 15, wherein the alcohol ether is one or more selected from the group consisting of ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, propylene glycol monobutyl ether, and propylene glycol dibutyl ether.

18. The composition of claim 1, wherein said composition further comprises water.

19. A method of using the composition of any of claims 1-18, wherein the nickel-plated workpiece is dipped with a water-soluble weldable nickel protectant at a temperature of 50-55 ℃ for 5-90 seconds, and then dried with hot air after the dipping.

20. The use method of claim 19, wherein the workpiece is used as a cathode, the stainless steel is used as an anode, a cathodic electrolysis assisted soaking process is adopted, and the voltage is controlled to be 5-8V.