Soldering flux for nickel-plated alloy soft soldering pre-coating and coating method

Abstract

The invention discloses a soldering flux for nickel-plated alloy soft soldering precoating. The soldering flux comprises the following components in percentage by weight: 10%-50% of rosin, 1.0%-10% of organic acid, 2.0%-4.0% of organic amine, 0.5%-2% of inorganic metal salt, 0.5%-2.0% of an activity enhancer, 0.5%-2.0% of a surfactant, 0.5%-2.0% of a corrosion inhibitor, 0.1%-2.0% of an additive and the balance of a solvent, the coating method comprises the steps that scaling powder is prepared according to the original component materials, the water bath temperature is constant, a soldering lug is flatly laid on a polytetrafluoroethylene plastic plate to be preheated for half a minute at the temperature of 90-100 DEG C, a proper scaling powder solution for constant-temperature pre-coating is dropwise added to the soldering lug, heating and drying are conducted after uniform brushing, cooling is conducted to the room temperature after drying, and then the formed soldering lug pre-coated with the scaling powder is obtained. The problems that an existing soldering flux is not easy to coat when being used for pre-coating the soldering lug, soldering flux coatings are adhered due to mutual contact and pressing, and powder falls off when the soldering lug coated with the soldering flux is cut are solved. The flux is short in welding time and good in wettability, residues after welding are easy to clean, and meanwhile welding of various metal materials such as nickel and nickel alloy and aluminum and aluminum alloy can be completed.

Description

Technical Field

[0001] The invention relates to a nickel-plated layer soldering flux, and in particular to a nickel-plated layer alloy soldering pre-coating flux and a coating method thereof. Background Art

[0002] At present, with the rapid development of science and technology, electronic packaging technology is of vital importance. In the process of electronic packaging, pre-coated solder sheets play a key role. Pre-coated solder sheets refer to a layer of flux coated on preformed solder sheets. When used, they can be directly assembled with devices, or made into various shapes according to needs. They are widely used in PCB assembly, automotive parts components, connectors and terminal equipment, chip connection, power module substrate attachment, filter connectors and electronic component assembly. Compared with welding wire or solder paste, pre-coated solder sheets have precise solder volume and quantitative flux, which can ensure welding consistency and stability. However, different weldments have different requirements for pre-coated solder sheets. For example, nickel and nickel alloys, aluminum and aluminum alloys, etc. require highly active flux to break the oxide film and meet the coating process of the solder sheet welding environment.

[0003] Nickel-plated alloys are often used in the manufacture of electronic components, connectors, circuit boards, etc. due to their high hardness, high wear resistance, high corrosion resistance and excellent electrical conductivity. The present invention is based on the research of forming a nickel-plated alloy plate by chemical nickel plating on the surface of copper. The chemical nickel-plated alloy layer has a stable molecular structure, but an uneven and irregular oxide film will be formed on the surface of the coating. During welding, the tin alloy and the coating cannot effectively contact each other, and an alloy layer cannot be formed, resulting in welding failure. How to effectively remove the oxide film, improve welding efficiency, reduce residues, and select a suitable coating process so that the pre-coated solder sheets touch each other without sticking and cutting without losing powder is the key to the pre-coating flux for nickel-plated alloy soft soldering.

[0004] At present, there are some reports on the pre-coating flux for nickel-plated soft soldering in China. The main components of the flux described in the patent for a nickel-plated alloy soft soldering solder wire core with patent number CN201210250851.2 are: 60-90% resin, 0.1-20% organic acid, 0.1-10% organic amine, 0.1-20% metal salt, 0.1-2.0% activity enhancer, 0.1-2.0% surfactant, 0.1-1.0% corrosion inhibitor and 0.1-1.0% antioxidant. The flux is solid at room temperature and is heated and applied to the solder sheet. After cooling, the flux coating is viscous, which is not convenient for storage and use. At the same time, it is difficult to apply and the coating cost is high. Patent application number 201811155980.7 is a flux for solder core of multi-metal materials soldering. The main components of the flux are 20-80% of alkyd ionic liquid active component, 5-20% of zinc fluoroborate, 5-30% of zinc oxide, 5-20% of basic zinc carbonate, 0.1-2% of surfactant, and 0.05-0.1% of corrosion inhibitor. The characteristic of the flux is that the synthetic alkyd ionic liquid active component is used as a film remover, and then matched with a surfactant. Although this type of flux has good activity and low solid content, it is not suitable for pre-coated solder sheets. It cannot form a film when coated. The flux can only be used in conjunction with solder. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a pre-coating flux for nickel-plated alloy soldering and a coating method thereof. The present invention solves the problems that the existing flux is difficult to coat for pre-coating solder sheets, the flux coatings stick to each other when pressed against each other, and the solder sheets coated with flux fall off when cut. The flux used has a short welding time, good wettability, and easy cleaning of the residue after welding. It can also be used for welding various metal materials such as nickel and nickel alloys, aluminum and aluminum alloys.

[0006] To achieve the above object, the present invention adopts the following scheme:

[0007] A nickel-plated alloy soldering pre-coating flux comprises the following components by weight percentage:

[0008] Rosin 10%-50%, organic acid 1.0%-10%, organic amine 2.0%-4.0%, inorganic metal salt 0.5%-2%, activity enhancer 0.5%-2.0%, surfactant 0.5%-2.0%, corrosion inhibitor 0.5%-2.0%, additive 0.1%-2.0%, the rest is solvent, and the total mass percentage of all components is 100%;

[0009] Preferably, the additive is 2-pyridinecarboxylic acid, and its molecular structure is:

[0010] It can form catalytically active complexes with metal elements such as nickel and cobalt, and can especially react with inorganic metal salts to produce acidic gases such as HCl that remain in the flux; the general reaction formula is:

[0011]

[0012] Preferably, the rosin is at least one or two of AXE, ice white rosin, hydrogenated rosin, and water white rosin;

[0013] Preferably, the organic acid is any two of succinic acid, sebacic acid, stearic acid, glutaric acid, salicylic acid, DL-malic acid, and palmitic acid;

[0014] Preferably, the organic amine is one or two of monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, and diisopropanolamine;

[0015] Preferably, the inorganic metal salt is any one of zinc chloride, stannous chloride, bismuth chloride and nickel chloride;

[0016] Preferably, the activity enhancer is one or two of hexadecyltrimethylammonium bromide, diethylammonium hydrochloride, and cyclohexylamine hydrochloride;

[0017] Preferably, the surfactant is one or two of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and phosphate ester;

[0018] Preferably, the corrosion inhibitor is benzotriazole;

[0019] Preferably, the solvent is 1,2-propylene glycol;

[0020] The preparation method of the above-mentioned nickel-plated alloy soldering pre-coating flux is as follows:

[0021] (1) Weigh the formula components according to the weight percentage, then put the organic acid, inorganic metal salt, active agent, surfactant, and corrosion inhibitor into a container, and stir continuously for 5 minutes to 10 minutes to mix them evenly;

[0022] (2) Add rosin and solvent to another reactor, heat in a water bath at 75°C to 95°C and stir magnetically for 5 to 10 minutes to completely dissolve the rosin in the solvent. The dissolved solution is a light yellow transparent liquid.

[0023] (3) slowly adding the powdery mixed agent obtained by mixing evenly in the above step (1) to the above solution (2) and heating it in a water bath at 75°C to 95°C, stirring it magnetically for 5min to 10min, then adding the organic amine and the surfactant and continuing to stir for 5min to 10min, and after all the raw materials are mixed and dissolved evenly, a pre-coating flux for nickel-plated alloy soldering is obtained;

[0024] The present invention also provides a method for coating the above soldering flux onto a soldering sheet, comprising the following steps:

[0025] Prepare the flux according to the original component materials, and then keep the temperature in a water bath; lay the welding piece flat on the polytetrafluoroethylene plastic plate and preheat it at 90℃~100℃ for half a minute, drop appropriate pre-coating flux solution on the welding piece, apply it evenly, heat and dry it, and cool it to room temperature after drying to obtain the pre-coated flux molded welding piece.

[0026] Preferably, the water bath thermostat temperature is 75°C to 95°C.

[0027] Preferably, the drying temperature is 90° C. to 115° C., and the drying time is 30 min to 60 min.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] (1) The present invention adds a unique additive 2-pyridine carboxylic acid, which can form a complex with catalytic activity with metal elements such as nickel and cobalt, and can especially react with inorganic metal salts to produce acidic gases such as HCl. At the same time, the added activity enhancer contains Cl-, Br - Acid ions such as ions can promote the production of acidic gases.

[0030] The soldering flux of the present invention is a liquid rosin-based soldering flux (the solvent is 1,2-propylene glycol) before coating, which can greatly absorb the HCl gas generated by the reaction, so that when the pre-coated formed solder piece is welded, the residual HCl can greatly destroy the oxide film on the surface of the nickel-plated mother material, and at the same time, the residual 2-pyridine carboxylic acid forms a catalytically active complex with the nickel element of the substrate, which promotes the wetting of the pre-formed solder piece to the substrate mother material during welding, and promotes the welding process of the entire pre-formed solder piece.

[0031] (2) The present invention makes the pre-coated solder flux easy to apply and simple to operate by cleverly designing the ratio of solid solder flux to solvent, and makes the solder flux coating non-sticky when touched and pressed, and has good non-stickiness. The pre-coated solder sheet using the solder flux has a larger spreading area and spreading rate, which can enhance the wetting ability and anti-retraction ability of the solder sheet.

[0032] (3) The nickel-plated alloy solder pre-coating flux designed by the present invention is not only suitable for lead solder sheet soldering, but also for lead-free solder sheet soldering. The succinic acid and sebacic acid generate cyclic lactone or lactide during soldering. The esters serve as good film-forming agents and form a film on the solder surface during soldering to prevent the solder from high-temperature oxidation and play a protective role, thereby making the solder joint surface fuller, brighter and smoother. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of a pre-coated formed solder sheet;

[0034] Figure 2 Comparison of solder joint morphology of the pre-coated molded solder sheet before (left) and after (right) welding in Example 1;

[0035] Figure 3 Comparison of solder joint morphology of the pre-coated molded solder sheet before (left) and after (right) welding in Example 2;

[0036] Figure 4 Comparison of the solder joint morphology of the pre-coated molded solder sheet before (left) and after (right) welding in Example 3;

[0037] Figure 5 Comparison of the solder joint morphology of the pre-coated molded solder sheet before (left) and after (right) welding in Example 4;

[0038] Figure 6 Comparison of the solder joint morphology of the pre-coated molded solder sheet before (left) and after (right) welding in Example 5;

[0039] In the attached Figure 1 Middle: 1. Flux coating; 2. Preformed solder sheet; DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to specific embodiments.

[0041] Example 1

[0042] A nickel-plated alloy soldering pre-coating flux is composed of the following components:

[0043] The mass ratio of rosin AXE is 10%, the mass ratio of organic acid is a mixture of succinic acid and stearic acid, 7%, succinic acid: stearic acid = 2:5, the mass ratio of organic amine triethanolamine is 2%, the mass ratio of inorganic metal salt bismuth chloride is 0.5%, the mass ratio of active agent enhancer cyclohexylamine hydrochloride is 0.5%, the mass ratio of active enhancer octylphenol polyoxyethylene ether is 0.5%, the mass ratio of corrosion inhibitor benzotriazole is 1%, the mass ratio of additive 2-pyridinecarboxylic acid is 2%, and the balance is 1,2-propylene glycol solution.

[0044] The preparation method comprises the following steps:

[0045] 1) Weigh an appropriate amount of 1,2-propylene glycol solution according to the weight percentage into a reactor and heat it in a water bath at 75° C.;

[0046] 2) After the temperature rises to 75° C., weigh AXE according to the formula and add it to the reactor in (1). After magnetic stirring for 10 minutes, AXE is completely dissolved in 1,2-propylene glycol, and the solution becomes light yellow and transparent;

[0047] 3) According to the formula, weigh powdered succinic acid, stearic acid, bismuth chloride, cyclohexylamine hydrochloride, benzotriazole, and picolinic acid, mix them evenly, and add them to the solution in (2), and stir magnetically for 10 minutes to completely dissolve the powdered reagents in the solution;

[0048] 4) weighing triethanolamine and octylphenol polyoxyethylene ether according to the formula and adding them to the solution in (3), and stirring magnetically for 10 minutes to obtain a pre-coating flux for nickel-plated alloy soldering;

[0049] 5) Lay the solder sheet flat on the plastic plate, preheat at 100℃ for 30s, and use a dropper to 1.5cm 2 / drops are added onto the soldering sheet, and then the soldering flux is evenly applied on the soldering sheet, and then heated and baked at 100℃ for about 30min, and then cooled after drying to obtain the pre-flux-coated molded soldering sheet.

[0050] The pre-coated flux-formed solder sheet prepared by the ratio in this case has a solder flux coating that does not stick to the touch and has good non-stickiness. There is less volatile smoke during welding, and the solder joints are bright and have a better spreading effect. The added 2-picolinic acid can greatly promote the wetting and spreading of the solder sheet on the substrate. The added bismuth chloride and cyclohexylamine hydrochloride can form an active complex with 2-picolinic acid. At the same time, HCl gas is produced and adsorbed on the flux coating layer, which can enhance the wetting ability and anti-retraction ability of the solder sheet during welding.

[0051] Example 2

[0052] A nickel-plated alloy soldering pre-coating flux is composed of the following components:

[0053] The rosin is a mixture of AXE and water-white rosin with a mass ratio of 22%, AXE: water-white rosin = 15:7; the organic acid is a mixture of salicylic acid and sebacic acid with a mass ratio of 10%, salicylic acid: sebacic acid = 3:7; the organic amine triethanolamine has a mass ratio of 2.5%, the inorganic metal salt stannous chloride has a mass ratio of 0.6%, the active agent enhancer hexadecyltrimethylammonium bromide has a mass ratio of 0.7%, the surfactant octylphenol polyoxyethylene ether has a mass ratio of 0.7%, the corrosion inhibitor benzotriazole has a mass ratio of 1%, the additive picolinic acid has a mass ratio of 1.5%, and the balance is 1,2-propylene glycol solution.

[0054] The preparation method comprises the following steps:

[0055] 1) Weigh an appropriate amount of 1,2-propylene glycol according to the weight percentage into a reactor and heat in a water bath at 75° C.;

[0056] 2) After the temperature rises to 75° C., weigh AXE and water-white rosin according to the formula and add them to the reactor in (1). After magnetic stirring for 10 minutes, AXE and water-white rosin are completely dissolved in 1,2-propylene glycol, and the solution is light yellow and transparent;

[0057] 3) According to the formula, weigh powdered salicylic acid, sebacic acid, stannous chloride, hexadecyltrimethylammonium bromide, benzotriazole, and picolinic acid, mix them evenly, and add them to the solution in (2), and stir magnetically for 10 minutes to allow the powdered reagents to completely dissolve in the solution;

[0058] 4) weighing triethanolamine and octylphenol polyoxyethylene ether according to the formula and adding them to the solution in (3), and stirring magnetically for 10 minutes to obtain a pre-coating flux for nickel-plated alloy soldering;

[0059] 5) Lay the solder sheet flat on the plastic plate, preheat at 100℃ for 30s, and use a dropper to 1.5cm 2 / drops are added onto the soldering sheet, and then the soldering flux is evenly applied on the soldering sheet, and then heated and baked at 100℃ for about 30min, and then cooled after drying to obtain the pre-flux-coated molded soldering sheet.

[0060] In this case, a pre-coating flux with better performance was obtained by compounding different rosins with different organic acids. The compounding of different rosins enables it to meet the process standards during coating, has good non-stickiness, and is cuttable, that is, the flux coating does not fall off during cutting. In terms of solder wetting performance, the added 2-pyridinecarboxylic acid can fully react with stannous chloride and hexadecyltrimethylammonium bromide to form a catalytically active complex, thereby improving the activity of the flux. Its product HCl can also promote the wetting of the solder, break the surface oxide film of the parent substrate, and enhance the wetting ability and anti-retraction ability of the solder piece during welding.

[0061] Example 3

[0062] A nickel-plated alloy soldering pre-coating flux is composed of the following components:

[0063] The rosin is a mixture of AXE and ice white rosin in a mass ratio of 29%, AXE: ice white rosin = 22:7; the organic acid is a mixture of glutaric acid and stearic acid in a mass ratio of 8%, glutaric acid: stearic acid = 3:5; the organic amine diethanolamine has a mass ratio of 3%, the inorganic metal salt nickel chloride has a mass ratio of 1%, the active agent enhancer cyclohexylamine hydrochloride has a mass ratio of 1.2%, the surfactant phosphate has a mass ratio of 0.8%, the corrosion inhibitor benzotriazole has a mass ratio of 1%, the additive picolinic acid has a mass ratio of 2%, and the balance is 1,2-propylene glycol solution.

[0064] The preparation method comprises the following steps:

[0065] 1) Weigh an appropriate amount of 1,2-propylene glycol according to the weight percentage into a reactor and heat it in a water bath at 80° C.;

[0066] 2) After the temperature rises to 80° C., weigh AXE and ice white rosin according to the formula and add them to the reactor in (1). After magnetic stirring for 10 minutes, AXE and ice white rosin are completely dissolved in 1,2-propylene glycol, and the solution is light yellow and transparent;

[0067] 3) According to the formula, weigh powdered glutaric acid, stearic acid, nickel chloride, cyclohexylamine hydrochloride, benzotriazole, and picolinic acid, mix them evenly, and add them to the solution in (2), and stir magnetically for 10 minutes to allow the powdered reagents to completely dissolve in the solution;

[0068] 4) weighing triethanolamine and phosphate according to the formula and adding them to the solution in (3), and stirring magnetically for 10 minutes to obtain a nickel-plated alloy soldering pre-coating flux;

[0069] 5) Lay the solder sheet flat on the plastic plate, preheat at 100℃ for 30s, and use a dropper to 1.5cm 2 / drops are added onto the soldering sheet, and then the soldering flux is evenly applied on the soldering sheet, and then heated and baked at 100℃ for about 30min, and then cooled after drying to obtain the pre-flux-coated molded soldering sheet.

[0070] The coating flux prepared in this case can greatly promote the welding piece to the nickel-plated substrate, and the compound of different rosins makes it non-sticky and cuttable. 2-Pyridinecarboxylic acid can be used as an active agent to break the oxide film of the nickel-plated substrate, and can form catalytic active complexes with Ni2+ to enhance the activity of the flux. The added nickel chloride and cyclohexylamine hydrochloride have a promoting effect on the reaction. The HCl produced by it can greatly destroy the oxide film on the surface of the substrate, promote the wetting of the preformed welding piece to the substrate base material during welding, and promote the entire preformed welding process.

[0071] Example 4

[0072] A nickel-plated alloy soldering pre-coating flux is composed of the following components:

[0073] The rosin is a mixture of AXE and hydrogenated rosin with a mass ratio of 33%, AXE: hydrogenated rosin = 27:6; the organic acid is a mixture of succinic acid and sebacic acid with a mass ratio of 8%, succinic acid: sebacic acid = 2:6; the organic amine triethanolamine has a mass ratio of 3%, the inorganic metal salt stannous chloride has a mass ratio of 1%, the activator enhancer diethylammonium hydrochloride has a mass ratio of 0.7%, the surfactant phosphate has a mass ratio of 0.7%, the corrosion inhibitor benzotriazole has a mass ratio of 1%, the additive picolinic acid has a mass ratio of 1.5%, and the balance is 1,2-propylene glycol solution.

[0074] The preparation method comprises the following steps:

[0075] 1) Weigh an appropriate amount of 1,2-propylene glycol according to the weight percentage into a reactor and heat it in a water bath at 80° C.;

[0076] 2) After the temperature rises to 80° C., weigh AXE and hydrogenated rosin according to the formula and add them to the reactor in (1). After magnetic stirring for 10 minutes, AXE and hydrogenated rosin are completely dissolved in 1,2-propylene glycol, and the solution is light yellow and transparent;

[0077] 3) According to the formula, weigh powdered succinic acid, sebacic acid, stannous chloride, diethylamine hydrochloride, benzotriazole, and picolinic acid, mix them evenly, and add them to the solution in (2), and stir magnetically for 10 minutes to completely dissolve the powdered reagents in the solution;

[0078] 4) weighing triethanolamine and phosphate according to the formula and adding them to the solution in (3), and stirring magnetically for 10 minutes to obtain a nickel-plated alloy soldering pre-coating flux;

[0079] 5) Lay the solder sheet flat on the plastic plate, preheat at 100℃ for 30s, and use a dropper to 1.5cm 2 / drops are added onto the soldering sheet, and then the soldering flux is evenly applied on the soldering sheet, and then heated and baked at 100℃ for about 30min, and then cooled after drying to obtain the pre-flux-coated molded soldering sheet.

[0080] The pre-coated flux-formed solder sheet in this case has excellent performance. The compound of organic acids succinic acid and sebacic acid generates cyclic lactones or lactides during brazing. Esters act as good film-forming agents and form films on the surface of the solder during welding, making the solder joint surface full, bright and smooth. The additive 2-pyridinecarboxylic acid has a significant effect on breaking the oxide film of the substrate and wetting the solder during the brazing process. The 2-pyridinecarboxylic acid nickel complex produced by it can enhance the activity of the flux, ensuring that the flux has a certain activity throughout the entire welding process, and the resulting solder joints are bright and smooth.

[0081] Example 5

[0082] A nickel-plated alloy soldering pre-coating flux is composed of the following components:

[0083] The rosin is a mixture of AXE and ice white rosin in a mass ratio of 33%, AXE: ice white rosin = 27:6; the organic acid is a mixture of succinic acid and sebacic acid in a mass ratio of 8%, succinic acid: sebacic acid = 2:6; the organic amine triethanolamine has a mass ratio of 3%, the inorganic metal salt stannous chloride has a mass ratio of 0.8%, the active agent enhancer hexadecyltrimethylammonium bromide has a mass ratio of 1%, the surfactant alkylphenol polyoxyethylene ether has a mass ratio of 1%, the corrosion inhibitor benzotriazole has a mass ratio of 1%, the additive picolinic acid has a mass ratio of 2%, and the balance is 1,2-propylene glycol solution.

[0084] The preparation method comprises the following steps:

[0085] 1) Weighing an appropriate amount of 1,2-propylene glycol according to the weight percentage and heating it in a water bath at 85° C. in a reactor;

[0086] 2) After the temperature rises to 85° C., weigh AXE and ice white rosin according to the formula and add them to the reactor in (1). After magnetic stirring for 10 minutes, AXE and ice white rosin are completely dissolved in 1,2-propylene glycol, and the solution is light yellow and transparent;

[0087] 3) According to the formula, weigh powdered succinic acid, sebacic acid, stannous chloride, hexadecyltrimethylammonium bromide, benzotriazole, and picolinic acid, mix them evenly, and add them to the solution in (2), and stir magnetically for 10 minutes to completely dissolve the powdered reagents in the solution;

[0088] 4) weighing triethanolamine and alkylphenol polyoxyethylene ether according to the formula and adding them to the solution in (3), and stirring magnetically for 10 minutes to obtain a pre-coating flux for nickel-plated alloy soldering;

[0089] 5) Lay the solder sheet flat on the plastic plate, preheat at 100℃ for 30s, and use a dropper to 1.5cm 2 / drops are added onto the soldering sheet, and then the soldering flux is evenly applied on the soldering sheet, and then heated and baked at 100℃ for about 30min, and then cooled after drying to obtain the pre-flux-coated molded soldering sheet.

[0090] The coating flux prepared in this case can be used for coating of various solder sheets, such as Sn63Pb37, SAC305 and other solder sheets. The flux is in liquid state before coating, which is convenient for controlling the thickness of the flux coating layer and can evenly distribute the active ingredients of the flux, thus avoiding uneven spreading of the solder sheet during welding and reducing pores. At the same time, the 2-pyridinecarboxylic acid in the flux is evenly coated on the preformed solder sheet in the liquid flux. When welding with the nickel-plated substrate, the contact area is large and the reaction is sufficient, which can effectively increase the solder spreading rate and spreading area.

[0091] Example 6

[0092] A nickel-plated alloy soldering pre-coating flux is composed of the following components:

[0093] The rosin is a mixture of ice white rosin and AXE in a mass ratio of 30%, with ice white rosin:AXE=2:1; the organic acid is a mixture of succinic acid and palmitic acid in a mass ratio of 8%, with succinic acid:palmitic acid=2:6; the organic amine triethanolamine has a mass ratio of 3%, the inorganic metal bismuth chloride has a mass ratio of 1%, the active agent enhancer hexadecyltrimethylammonium bromide has a mass ratio of 0.8%, the surfactant phosphate has a mass ratio of 1%, the corrosion inhibitor benzotriazole has a mass ratio of 1%, the additive picolinic acid has a mass ratio of 2%, and the balance is 1,2-propylene glycol solution.

[0094] The preparation method comprises the following steps:

[0095] 1) Weighing an appropriate amount of 1,2-propylene glycol according to the weight percentage and heating it in a water bath at 90° C. in a reactor;

[0096] 2) After the temperature rises to 90° C., weigh ice white rosin and AXE according to the formula and add them to the reactor in (1). After magnetic stirring for 10 minutes, AXE and ice white are completely dissolved in 1,2-propylene glycol, and the solution is light yellow and transparent;

[0097] 3) According to the formula, weigh powdered succinic acid, palmitic acid, bismuth chloride, hexadecyltrimethylammonium bromide, benzotriazole, and picolinic acid, mix them evenly, and add them to the solution in (2), and stir magnetically for 10 minutes to completely dissolve the powdered reagents in the solution;

[0098] 4) weighing triethanolamine and phosphate according to the formula and adding them to the solution in (3), and stirring magnetically for 10 minutes to obtain a nickel-plated alloy soldering pre-coating flux;

[0099] 5) Lay the solder sheet flat on the plastic plate, preheat at 110℃ for 30s, and use a dropper to 1.5cm 2 / drops are added onto the soldering sheet, and then the soldering flux is evenly applied on the soldering sheet, and then heated and baked at 110℃ for about 30min, and then cooled after drying to obtain the pre-flux-coated molded soldering sheet.

[0100] The pre-coated flux-formed solder sheet in this case has excellent performance and can effectively weld metals such as nickel and nickel alloys. The addition of 2-pyridine carboxylate can enhance the activity of the flux, and its metal complexes and reaction products can effectively remove the oxide film of the parent substrate, effectively improving the wetting rate and anti-shrinkage ability.

[0101] By adding 2-pyridinecarboxylic acid, the spreading rate is improved to different degrees (as shown in Table 1). After adding 2-pyridinecarboxylic acid, the improvement in the above cases is 2.9%, 1.94%, 5.62%, 3.61%, 4.11%, and 6.03%. By adding additives to improve the spreading rate, dewetting and dewetting do not occur during welding.

[0102] Table 1 Comparison of spreading rate before and after adding 2-pyridine carboxylic acid

[0103]

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the technical solution. Although the applicant has described the present application in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that those modifications or equivalent substitutions of the technical solution of the present application without departing from the purpose and scope of the technical solution of the present application should be included in the scope of the claims of the present application.

Claims

1. A nickel-plated alloy soldering pre-coating flux, characterized in that: The components by weight percentage include: Rosin 10%-50%, organic acid 1.0%-10%, organic amine 2.0%-4.0%, inorganic metal salt 0.5%-2%, activity enhancer 0.5%-2.0%, surfactant 0.5%-2.0%, corrosion inhibitor 0.5%-2.0%, additive 0.1%-2.0%, the rest is solvent, and the total mass percentage of all components is 100%; The rosin is at least one or two of AXE, ice white rosin, hydrogenated rosin, and water white rosin; The organic acid is any two of succinic acid, sebacic acid, stearic acid, glutaric acid, salicylic acid, DL-malic acid, and palmitic acid; The organic amine is one or two of monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine and diisopropanolamine; The inorganic metal salt is any one of zinc chloride, stannous chloride, bismuth chloride and nickel chloride; The activity enhancer is one or two of hexadecyltrimethylammonium bromide, diethylammonium hydrochloride, and cyclohexylamine hydrochloride; The surfactant is one or two of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and phosphate ester; The corrosion inhibitor is benzotriazole; The solvent is 1,2-propylene glycol; The additive is picolinic acid.

2. The method for preparing a nickel-plated alloy soldering pre-coating flux according to claim 1, characterized in that: The following steps are involved: (1) Weigh the formula components according to the weight percentage, and then put the organic acid, inorganic metal salt, active agent, surfactant, and corrosion inhibitor into a container in sequence, and stir continuously for 5 minutes to 10 minutes to mix them evenly; (2) Add rosin and solvent to another reactor, heat in a water bath at 75°C to 95°C and stir magnetically for 5 to 10 minutes to completely dissolve the rosin in the solvent. The dissolved solution is a light yellow transparent liquid. (3) Slowly add the powdery mixed agent obtained by mixing evenly in the above step (1) to the above solution (2), heat it in a water bath at 75°C to 95°C, stir it magnetically for 5min to 10min, then add the organic amine and surfactant and continue stirring for 5min to 10min. After all the raw materials are mixed and dissolved evenly, a pre-coating flux for nickel-plated alloy soft soldering is obtained.

3. The coating method of a nickel-plated alloy soldering pre-coating flux according to claim 1, characterized in that: The following steps are involved: Prepare a constant temperature water bath with flux according to the original component materials, lay the soldering sheet flat on a polytetrafluoroethylene plastic plate and preheat it at 90°C to 100°C for half a minute, drop appropriate constant temperature pre-coating flux solution on the soldering sheet, apply it evenly and heat and dry it, and then cool it to room temperature to obtain a pre-coated flux molded soldering sheet.

4. A method for coating a nickel-plated alloy soldering pre-coating flux according to claim 3, characterized in that: The water bath constant temperature is 75° C. to 95° C., the drying temperature is 90° C. to 115° C., and the drying time is 30 min to 60 min.

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