Direct secondary use flux diluent for soldering and method of use

Abstract

The application discloses a diluent for directly recycling hair dry tin paste, which is composed of an active agent, a stabilizer and a solvent; the active agent is composed of p-tert-butyl phenylacetic acid and 2-hydrazino-2-imidazoline hydrobromide; the stabilizer is composed of two or more than two of 4-sulfonic acid benzotriazole, hexadecylamine, trimethylolpropane and pentaerythritol; and the solvent is composed of dimethyl succinate and mixed five glycol dimethyl ether. Compared with directly scrapped hair dry tin paste, the hair dry tin paste diluent prepared by the method has the advantages of simple preparation process, low cost, fast and effective complete fusion with the hair dry tin paste, direct realization of secondary utilization of the hair dry tin paste, simple use, wide application in various types of hair dry tin paste and direct addition to the hair dry tin paste for mixing and stirring on an SMT production line.

Description

Technical Field

[0001] This invention relates to the field of recycled solder paste, specifically to a diluent for direct reuse of dried solder paste and its application method. Background Technology

[0002] Solder paste is a key material in the assembly of miniaturized electronic products. During the soldering process, the fully molten solder spreads and wets the pads and components to achieve the connection between the pads and the components. The quality of solder paste directly affects the soldering quality of the substrate, and the quality of solder paste is determined by whether it has good solderability, excellent storage properties, stability in use, and stable and reliable residue.

[0003] The flux in solder paste (mainly composed of rosin resin, organic acids, organic amines, solvents, thixotropic agents, etc.) is the most critical component. Its function is to remove metal oxides from components and the surface oxide film on the metal pads of the circuit board, and to protect the solder from secondary oxidation during the soldering process. However, in reality, with prolonged printing of solder paste on SMT production lines, the flux corrodes the surface of the solder powder, causing the solder paste viscosity to increase or dry out, rendering it unusable. Expired solder paste may also exhibit increased viscosity or dryness.

[0004] To address the issue of solder paste drying out during use, patent CN107214431A describes a method where solder powder is soaked in a mixture of hydroquinone epoxy resin, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, ε-hydroxyhexanoic acid lactone, and α-hydroxycarboxylic acid ester. The resulting powder is then heated and dried or exposed to ultraviolet light to form a surface coating. The solder paste is then stirred with flux to produce a paste suitable for room temperature storage. Patent CN101745636A, entitled "A Method for Preparing Antioxidant Solder Powder," describes a method where the oxide film on the surface of the solder powder is removed before surface coating with sodium dodecyl sulfate, alkylphenol polyoxyethylene ether, and polyethylene glycol. The hydrophilic groups in the coating agent adsorb onto the metal surface of the solder powder to form a coating film. Although both methods involve pre-treating the solder powder to form a coating and prepare a solder paste resistant to drying out, in actual production, some solder pastes still experience prolonged storage or expired storage, especially on SMT production lines where prolonged printing leads to increased viscosity or drying out, rendering the solder paste unusable.

[0005] Currently, SMT production lines directly scrap solder paste that has increased viscosity during storage, increased viscosity during long-term printing, or dried out, resulting in a waste of resources. The scrapped solder paste is usually processed by melting it back into solder ingots, which generates a large amount of waste gas and slag, polluting the environment and consuming a lot of energy. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a diluent for direct reuse of recycled solder paste that can be quickly and completely integrated with dry solder paste, has a simple preparation method, a simple usage method, and a low cost, as well as its usage method.

[0007] The technical solution of the present invention is as follows:

[0008] A diluent for direct reuse of dried solder paste, wherein the diluent is composed of an activator, a stabilizer, and a solvent; the activator is a mixture of p-tert-butylphenylacetic acid and 2-hydrazino-2-imidazoline hydrobromide; the stabilizer is composed of two or more of benzotriazole sulfonate, hexadecylamine, trimethylolpropane, and pentaerythritol; and the solvent is a mixture of dimethyl succinate and pentaethylene glycol dimethyl ether.

[0009] Furthermore, the diluent consists of 1% to 3% activator, 29% to 44% stabilizer and 53% to 70% solvent by weight percentage.

[0010] The method for using the diluent described in this invention comprises the following steps:

[0011] S1. The activator, stabilizer and solvent are added to a container in proportion and stirred to dissolve to prepare a diluent;

[0012] S2. Depending on the degree of drying of the solder paste, add the diluent mentioned in step S1 to the solder paste at a weight percentage of 0.05% to 0.4%, stir evenly with a plastic stirring blade, and put it into production directly.

[0013] Furthermore, the viscosity range of the drying solder paste is 200 Pa·s to 1000 Pa·s.

[0014] The beneficial effects of this invention are:

[0015] 1. Compared to directly discarding dried solder paste, the diluent of this invention can quickly and effectively blend with the dried solder paste, directly enabling its reuse. The activator effectively compensates for the loss of active substances in the dried solder paste. The stabilizer is dissolved and dispersed in the solder paste, and reacts with tin oxide and stannous oxide on the surface of the solder powder to form a stabilizer-Sn complex, forming a very thin film on the surface of the solder powder, effectively reducing the chemical reaction between acid radical ions and the solder powder and improving the drying resistance of the solder paste. The solvent in the diluent significantly reduces the viscosity of the dried solder paste.

[0016] 2. The diluent of the present invention has low cost, simple preparation method and simple use method. It can be widely used in various types of dry solder paste, or it can be directly added to the dry solder paste in the SMT production line for mixing and stirring. Attached Figure Description

[0017] Figure 1 This is a comparison image showing the process before and after adding the thinner of this invention to the solder paste. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the embodiments.

[0019] Example 1

[0020] The diluent for direct reuse of dry solder paste and its usage method are as follows: 1g of p-tert-butylphenylacetic acid, 1g of 2-hydrazino-2-imidazoline hydrobromide, 15g of 4-sulfonic acid benzotriazole, 23g of hexadecylamine, 30g of dimethyl succinate, and 30g of pentaethylene glycol dimethyl ether are added to a container and stirred evenly to prepare the diluent.

[0021] like Figure 1 As shown, depending on the degree of solder paste drying, the above-mentioned diluent is added to the dried solder paste with a viscosity of 255 Pa·s at a weight percentage of 0.05%. The dried solder paste and diluent in the solder paste container are thoroughly stirred with a plastic stirring blade to obtain solder paste with the viscosity shown in Table 1, which can be put into production.

[0022] Example 2

[0023] The diluent for direct reuse of dried solder paste and its usage method are as follows: 1.5g of p-tert-butylphenylacetic acid, 1.5g of 2-hydrazino-2-imidazoline hydrobromide, 22g of pentaerythritol, 22g of trimethylolpropane, 23g of dimethyl succinate, and 30g of pentaethylene glycol dimethyl ether are added to a container and stirred evenly to prepare the diluent.

[0024] Depending on the degree of solder paste drying, add 0.4% by weight of the above-mentioned diluent to the dried solder paste with a viscosity of 1000 Pa·s. Use a plastic stirring blade to thoroughly stir the dried solder paste and diluent in the solder paste container to obtain solder paste with a suitable viscosity that can be put into production.

[0025] Example 3

[0026] The method for using a diluent for direct reuse of dried solder paste is as follows: 0.5g of p-tert-butylphenylacetic acid, 0.5g of 2-hydrazino-2-imidazoline hydrobromide, 14g of 4-sulfonic acid benzotriazole, 15g of trimethylolpropane, 30g of dimethyl succinate, and 40g of pentaethylene glycol dimethyl ether are added to a container and stirred evenly to prepare the diluent.

[0027] Depending on the degree of solder paste drying, add 0.05% by weight of the above-mentioned diluent to the dried solder paste with a viscosity of 260 Pa·s. Use a plastic stirring blade to thoroughly stir the dried solder paste and diluent in the solder paste container to obtain a solder paste with a suitable viscosity as shown in Table 1, which can then be put into production.

[0028] Example 4

[0029] The diluent for direct reuse of dried solder paste and its usage method are as follows: 1g of p-tert-butylphenylacetic acid, 1g of 2-hydrazino-2-imidazoline hydrobromide, 10g of 4-sulfonic acid benzotriazole, 10g of hexadecylamine, 15g of trimethylolpropane, 30g of dimethyl succinate, and 33g of pentaethylene glycol dimethyl ether are added to a container and stirred evenly to prepare the diluent.

[0030] Depending on the degree of solder paste drying, add 0.1% by weight of the above-mentioned diluent to the dried solder paste with a viscosity of 350 Pa·s. Use a plastic stirring blade to thoroughly stir the dried solder paste and diluent in the solder paste container to obtain the solder paste with the viscosity shown in Table 1, which can then be put into production.

[0031] Example 5

[0032] The diluent for direct reuse of dried solder paste and its usage method are as follows: 1g of p-tert-butylphenylacetic acid, 1g of 2-hydrazino-2-imidazoline hydrobromide, 8g of 4-sulfonic acid benzotriazole, 10g of hexadecylamine, 10g of trimethylolpropane, 5g of pentaerythritol, 32g of dimethyl succinate, and 33g of pentaethylene glycol dimethyl ether are added to a container and stirred evenly to prepare the diluent.

[0033] Depending on the degree of solder paste drying, add 0.2% by weight of the above-mentioned diluent to the dried solder paste with a viscosity of 560 Pa·s. Use a plastic stirring blade to thoroughly stir the dried solder paste and diluent in the solder paste container to obtain a solder paste with a suitable viscosity as shown in Table 1, which can then be put into production.

[0034] Example 6

[0035] The method for using a diluent for directly reusing dried solder paste is as follows: 0.1 kg of p-tert-butylphenylacetic acid, 0.1 kg of 2-hydrazino-2-imidazoline hydrobromide, 0.8 kg of 4-sulfonic acid benzotriazole, 1 kg of hexadecylamine, 1 kg of trimethylolpropane, 0.5 kg of pentaerythritol, 3.2 kg of dimethyl succinate, and 3.3 kg of pentaethylene glycol dimethyl ether are added to a container and stirred evenly to prepare the diluent.

[0036] Depending on the degree of solder paste drying, add 0.2% by weight of the above-mentioned diluent to the dried solder paste with a viscosity of 560 Pa·s. Use a plastic stirring blade to thoroughly stir the dried solder paste and diluent in the solder paste container to obtain a solder paste with a suitable viscosity as shown in Table 1, which can then be put into production.

[0037] Table 1 shows the test results of adding the diluents prepared in Examples 1-6 to the dried solder paste according to the degree of drying.

[0038] Table 1. Results of tests conducted on the addition of the diluents prepared in Examples 1-6 to the drying solder paste according to the degree of drying.

[0039]

[0040] As can be seen from the table above, the diluent of the present invention can be widely used in various types of dry solder paste, or it can be directly added to the dry solder paste in the SMT production line for mixing and stirring.

[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for directly reusing the thinner for drying solder paste, characterized in that, The diluent is composed of an active agent, a stabilizer, and a solvent; the active agent is a mixture of p-tert-butylphenylacetic acid and 2-hydrazino-2-imidazoline hydrobromide; the stabilizer is composed of two or more of benzotriazole sulfonate, hexadecylamine, trimethylolpropane, and pentaerythritol; the solvent is a mixture of dimethyl succinate and pentaethylene glycol dimethyl ether; the diluent is composed of 1%–3% active agent, 29%–44% stabilizer, and 53%–70% solvent by weight percentage. The specific usage steps are as follows: S1. The activator, stabilizer and solvent are added to a container in proportion and stirred to dissolve to prepare a diluent; S2. Depending on the degree of drying of the solder paste, add the diluent mentioned in step S1 to the solder paste at a weight percentage of 0.05% to 0.4%, stir evenly with a plastic stirring blade, and put it directly into production; the viscosity range of the solder paste is 200 Pa·s to 1000 Pa·s.

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