Rosin type soldering flux for indium-based low-temperature soldering paste and preparation method of rosin type soldering flux

Abstract

The invention discloses rosin type soldering flux for indium-based low-temperature soldering paste and a preparation method of the rosin type soldering flux, and belongs to the technical field of brazing soldering flux. The soldering flux is prepared from the following components in percentage by weight: 40 to 60 percent of modified rosin, 2 to 5 percent of an organic acid activating agent, 0.5 to 2 percent of a halogen-containing compound, 2 to 5 percent of hydrogenated castor oil, 0.1 to 1 percent of benzotriazole, 0.1 to 1 percent of triethanolamine, 0.5 to 2 percent of a surfactant and 0.5 to 2 percent of paraffin oil. And the balance of an organic solvent. The method has the advantages that the prepared soldering flux is good in wettability and excellent in weldability, welding spots are bright and full, the welding void rate is as low as 2.4%, the heat conductivity can reach 43.12 W / mK, the welding spot shear strength can reach 13.45 MPa, and the soldering flux is suitable for low-temperature welding of indium-based brazing filler metal.

Description

Technical Field

[0001] The invention belongs to the technical field of brazing flux, and in particular relates to a rosin type flux for indium-based low-temperature solder paste and a preparation method thereof. Background Art

[0002] As a key process in the electronics manufacturing industry, low-temperature soldering technology is widely used in the assembly and connection of electronic components. Compared with traditional soldering processes, low-temperature soldering has significant advantages, including reducing damage to heat-sensitive materials, reducing energy consumption and improving production efficiency. Indium-based solder is a commonly used solder material in low-temperature soldering, with a low melting point and good wettability. The melting point of indium-based solder is usually below 200°C, which can significantly reduce the heat load on electronic components and substrates compared to traditional lead-based or tin-lead alloy solders. This makes indium-based solder particularly important in electronic devices with high precision and high reliability requirements, such as high-density integrated circuits, thin-film solar cells, and high-frequency radio frequency modules. Flux plays an important role in the soldering process, including removing oxides, improving the wettability and fluidity of solder, and avoiding cold soldering and virtual soldering of solder joints. Effective flux can not only improve the quality of solder joints, but also reduce the defect rate during the soldering process. For low-temperature soldering of indium-based solder, the design of the flux must adapt to its special melting characteristics to ensure the stability and reliability of the solder joints. Most of the existing indium-based solder fluxes face the problems of poor solderability, high solder void rate, insufficient heat dissipation performance, and low solder strength. Therefore, it is urgent to develop a new indium-based solder low-temperature soldering flux with good solderability, low solder void rate, excellent thermal conductivity, and high solder strength. Summary of the invention

[0003] The purpose of the present invention is to provide a rosin-type soldering flux for indium-based low-temperature solder paste and a preparation method thereof, which solves the problems of poor thermal conductivity, insufficient wettability, insufficient welding strength, and difficulty in meeting existing welding requirements of the solder paste caused by insufficient compatibility of the existing soldering flux with indium-based solder for low-temperature welding, and has the advantages of high activity, strong thermal conductivity, strong wettability, and excellent solderability.

[0004] The present invention

[0005] The rosin type flux for indium-based low-temperature solder paste is composed of the following components in percentage by weight: 40-60wt.% of modified rosin, 2-5wt.% of organic acid activator, 0.5-2wt.% of halogen-containing compound, 2-5wt.% of hydrogenated castor oil, 0.1-1wt.% of benzotriazole, 0.1-1wt.% of triethanolamine, 0.5-2wt.% of surfactant, 0.5-2wt.% of paraffin oil; the balance is organic solvent.

[0006] Among the above-mentioned flux ingredients, modified rosin acts as a film-forming agent, which can form a dense organic film on the surface of the solder joint during the welding process to prevent oxygen and moisture in the air from contacting the solder, thereby reducing welding defects such as cold soldering and false soldering, and protecting the solder joint. At the same time, it also provides a certain viscosity for the flux, making it have good solderability; the role of the organic acid activator is to remove the oxide layer on the surface of the solder and the weldment, and activate the metal surface during the welding process to improve the wettability of the solder paste; the halogen-containing compound has higher activation and stronger deoxidation ability, which helps to clean the metal surface and Improve welding performance; hydrogenated castor oil provides thixotropy for the flux, making its viscosity decrease under stress and having certain flow properties, and can restore viscosity in time when no stress is applied; benzotriazole is used to improve the antioxidant property of the flux and increase the service life of the flux; the role of triethanolamine is to remove oxides and impurities on the metal surface and adjust the pH value of the flux; the role of surfactant is to reduce the surface tension of the flux and increase the wettability of the flux to solder powder and pads; the role of paraffin oil is to adjust the viscosity and fluidity of the flux, making it easier to operate during the welding process.

[0007] Preferably, the modified rosin is one or a combination of hydrogenated rosin, polymerized rosin, KR-610 or KE-604 rosin.

[0008] Preferably, the organic acid activator is an organic acid having 2 to 10 carbon atoms;

[0009] Preferably, the organic acid activator is one or a combination of oxalic acid, adipic acid, succinic acid and glutaric acid.

[0010] Preferably, the halogen-containing compound is an organic amine hydrohalide and / or a halide;

[0011] Preferably, the organic amine hydrohalide is one or a combination of diethylamine hydrochloride, diethylamine hydrobromide, dimethylamine hydrochloride or triethylamine hydrochloride;

[0012] Preferably, the halogenated compound is one or a combination of dibromoethylbenzene or dibromobutylene glycol.

[0013] Preferably, the mass ratio of the organic acid activator to the halogen-containing compound is 1:0.2-0.5;

[0014] Preferably, the mass ratio of the organic acid activator to the organic amine hydrohalide salt is 1:0.2-0.3, and the mass ratio of the organic acid activator to the halide is 1:0.1-0.2.

[0015] Preferably, the surfactant is a nonionic surfactant;

[0016] Preferably, the surfactant is one or a combination of the fluorosurfactant FSN-100, OP-10, polyethylene oxide polypropylene oxide monobutyl ether.

[0017] Preferably, the organic solvent is a combination of fatty ether and fatty alcohol;

[0018] Preferably, the organic solvent is one or a combination of triethylene glycol monobutyl ether, tetraethylene glycol dimethyl ether, propylene glycol, and hexylene glycol.

[0019] The present invention also proposes a method for preparing the above-mentioned rosin-type flux for indium-based low-temperature solder paste, comprising: adding carrier rosin, organic acid activator, and benzotriazole into an organic solvent, stirring and dissolving at 100-120°C for 1-1.5 hours; then adding hydrogenated castor oil, stirring and dissolving at 70-90°C for 0.45-0.55 hours; finally adding halogen-containing compounds, surfactants and triethanolamine, stirring and dissolving at 50-70°C for about 1-2 hours; naturally cooling and standing for more than 12 hours to obtain the flux.

[0020] The beneficial effects of the present invention are:

[0021] (1) The operation method is simple, with few experimental steps, excellent repeatability and low cost; (2) The prepared indium-based low-temperature solder paste uses a rosin-type flux with good fluidity, a uniform paste and no precipitation and stratification; (3) It has good compatibility with indium-based solder, and the prepared solder paste has moderate viscosity, excellent anti-collapse performance, good spreading rate, bright and full solder joints formed after welding, little residue, and easy cleaning; (4) The solder joints after welding have excellent thermal conductivity and high shear strength, which meet the standard requirements of the electronics industry.

[0022] Description of the attached figure (please remove the background color in the figure)

[0023] Figure 1 This is a diagram showing the solder joint effect of a solder paste made by mixing the soldering flux described in Example 1 with In85Pb15Ag5 solder powder. DETAILED DESCRIPTION

[0024] The present invention is further described in conjunction with the following examples, but the embodiments of the present invention are not limited thereto.

[0025] Example 1

[0026] The present embodiment provides a rosin-type flux for indium-based low-temperature solder paste, characterized in that it is composed of the following components in weight percentage: 40wt.% of KR-610 rosin, 2wt.% of succinic acid, 3wt.% of adipic acid, 0.6wt.% of dibromoethylbenzene, 1.4wt.% of diethylamine hydrochloride, 5wt.% of hydrogenated castor oil, 0.5wt.% of benzotriazole, 0.3wt.% of triethanolamine, 1wt.% of paraffin oil, 1wt.% of FSN-100 surfactant, 18.4wt.% of hexylene glycol, and 26.8wt.% of tripropylene glycol butyl ether.

[0027] The method for preparing the rosin-type flux for the indium-based low-temperature solder paste described in this embodiment includes: adding KR-610 rosin, succinic acid, adipic acid, benzotriazole, and diethylamine hydrochloride to a mixed solvent of hexylene glycol and tripropylene glycol butyl ether, stirring and dissolving at 110° C. for 1 hour; then adding hydrogenated castor oil, stirring and dissolving at 90° C. for 0.5 hour; then adding FSN-100 surfactant, paraffin oil, triethanolamine, and dibromoethylbenzene, stirring and dissolving at 60° C. for 2 hours; cooling and standing for more than 12 hours to obtain the flux.

[0028] Example 2

[0029] The present embodiment provides a rosin-type flux for indium-based low-temperature solder paste, characterized in that it is composed of the following components in weight percentage: 40 wt.% of KR-610 rosin, 2 wt.% of succinic acid, 3 wt.% of glutaric acid, 2 wt.% of dibromoethylbenzene, 1 wt.% of diethylamine hydrochloride, 5 wt.% of hydrogenated castor oil, 0.5 wt.% of benzotriazole, 0.3 wt.% of triethanolamine, 1 wt.% of paraffin oil, 1 wt.% of FSN-100 surfactant, 22.1 wt.% of tetraethylene glycol dimethyl ether, and 22.1 wt.% of tripropylene glycol butyl ether.

[0030] The method for preparing the rosin-type flux for the indium-based low-temperature solder paste described in this embodiment includes: adding KR-610 rosin, succinic acid, glutaric acid, benzotriazole, and diethylamine hydrochloride to a mixed solvent of tetraethylene glycol dimethyl ether and tripropylene glycol butyl ether, stirring and dissolving at 110° C. for 1 hour; then adding hydrogenated castor oil, stirring and dissolving at 90° C. for 0.5 hour; then adding FSN-100 surfactant, paraffin oil, triethanolamine, and dibromoethylbenzene, stirring and dissolving at 60° C. for 2 hours; cooling and standing for more than 12 hours to obtain the flux.

[0031] Example 3

[0032] The present embodiment provides a rosin-type flux for indium-based low-temperature solder paste, characterized in that it is composed of the following ingredients in weight percentage: 40 wt.% of polymerized rosin, 5 wt.% of adipic acid, 0.6 wt.% of dibromoethylbenzene, 1.4 wt.% of diethylamine hydrochloride, 5 wt.% of hydrogenated castor oil, 0.5 wt.% of benzotriazole, 0.3 wt.% of triethanolamine, 1 wt.% of paraffin oil, 1 wt.% of polyethylene oxide polypropylene oxide monobutyl ether, 18.4 wt.% of hexylene glycol, and 26.8 wt.% of tripropylene glycol butyl ether.

[0033] The method for preparing the rosin-type flux for the indium-based low-temperature solder paste described in this embodiment includes: adding polymerized rosin, adipic acid, benzotriazole, and diethylamine hydrochloride to a mixed solvent of hexylene glycol and tripropylene glycol butyl ether, stirring and dissolving at 110° C. for 1 hour; then adding hydrogenated castor oil, stirring and dissolving at 80° C. for 0.5 hour; then adding polyethylene oxide polypropylene oxide monobutyl ether, paraffin oil, triethanolamine, and dibromoethylbenzene, stirring and dissolving at 60° C. for 1 hour; cooling and standing for more than 12 hours to obtain the flux.

[0034] Example 4

[0035] The present embodiment provides a rosin-type flux for indium-based low-temperature solder paste, characterized in that it is composed of the following ingredients in weight percentage: 40wt.% hydrogenated rosin, 4wt.% succinic acid, 1wt.% adipic acid, 1wt.% dibromoethylbenzene, 1wt.% diethylamine hydrochloride, 5wt.% hydrogenated castor oil, 0.5wt.% benzotriazole, 0.3wt.% triethanolamine, 1wt.% paraffin oil, 1wt.% OP-10 surfactant, 22.6wt.% tetraethylene glycol dimethyl ether, and 22.6wt.% tripropylene glycol butyl ether.

[0036] The method for preparing the rosin-type flux for the indium-based low-temperature solder paste described in this embodiment includes: adding polymerized rosin, succinic acid, adipic acid, benzotriazole, and diethylamine hydrochloride to a mixed solvent of tetraethylene glycol dimethyl ether and tripropylene glycol butyl ether, stirring and dissolving at 110° C. for 1 hour; then adding hydrogenated castor oil, stirring and dissolving at 90° C. for 0.5 hour; then adding OP-10 surfactant, paraffin oil, triethanolamine, and dibromoethylbenzene, stirring and dissolving at 60° C. for 1 hour; cooling and standing for more than 12 hours to obtain the flux.

[0037] Example 5

[0038] The present embodiment provides a rosin-type flux for indium-based low-temperature solder paste, characterized in that it is composed of the following components in weight percentage: 20 wt.% of KR-610 rosin, 20 wt.% of hydrogenated rosin, 2 wt.% of succinic acid, 3 wt.% of adipic acid, 1 wt.% of dibromoethylbenzene, 2 wt.% of diethylamine hydrochloride, 5 wt.% of hydrogenated castor oil, 0.5 wt.% of benzotriazole, 0.3 wt.% of triethanolamine, 1 wt.% of paraffin oil, 1 wt.% of OP-10 surfactant, 22.6 wt.% of tetraethylene glycol dimethyl ether, and 22.6 wt.% of tripropylene glycol butyl ether.

[0039] The method for preparing the rosin-type soldering flux for the indium-based low-temperature solder paste described in this embodiment comprises: adding KR-610 rosin, hydrogenated rosin, succinic acid, adipic acid, benzotriazole, and diethylamine hydrochloride to a mixed solvent of tetraethylene glycol dimethyl ether and tripropylene glycol butyl ether, and stirring and dissolving at 110° C. for 1 hour; then adding hydrogenated castor oil, and stirring and dissolving at 90° C. for 0.5 hour; then adding FSN-100 surfactant, paraffin oil, triethanolamine, and dibromoethylbenzene, and stirring and dissolving at 60° C. for 2 hours; cooling and standing for more than 12 hours to obtain the soldering flux.

[0040] Example 6

[0041] The present embodiment provides a rosin-type flux for indium-based low-temperature solder paste, characterized in that it is composed of the following components in weight percentage: 50wt.% of KE-604 rosin, 2wt.% of succinic acid, 3wt.% of adipic acid, 0.6wt.% of dibromoethylbenzene, 1.4wt.% of diethylamine hydrochloride, 5wt.% of hydrogenated castor oil, 0.5wt.% of benzotriazole, 0.3wt.% of triethanolamine, 1wt.% of paraffin oil, 1wt.% of FSN-100 surfactant, 17.6wt.% of tetraethylene glycol dimethyl ether, and 17.6wt.% of tripropylene glycol butyl ether.

[0042] The method for preparing the rosin-type flux for the indium-based low-temperature solder paste described in this embodiment comprises: adding KE-604 rosin, succinic acid, adipic acid, benzotriazole, and diethylamine hydrochloride to a mixed solvent of tetraethylene glycol dimethyl ether and tripropylene glycol butyl ether, and stirring and dissolving at 110° C. for 1 hour; then adding hydrogenated castor oil, and stirring and dissolving at 90° C. for 0.5 hour; then adding FSN-100 surfactant, paraffin oil, triethanolamine, and dibromoethylbenzene, and stirring and dissolving at 60° C. for 2 hours; cooling and standing for more than 12 hours to obtain the flux.

[0043] Table 1 shows the welding performance of the flux obtained in the embodiment

[0044] Spreading rate / % Void rate / % Thermal conductivity (W / mK) Shear strength(Mpa) Example 1 83.12 3.1 42.57 13.21 Example 2 81.76 5.6 41.68 13.45 Example 3 79.96 7.5 39.73 11.32 Example 4 81.65 5.3 43.12 11.95 Example 5 80.67 6.0 42.03 12.54 Example 6 82.33 2.4 41.40 12.82

[0045] The indium-based low-temperature solder paste prepared by the above method has good wettability with a rosin-type flux, excellent solderability, bright and full solder joints, a solder void rate as low as 2.4%, a thermal conductivity as high as 43.12W / mK, and a solder joint shear strength as high as 13.45MPa, and is suitable for low-temperature welding of indium-based solder.

[0046] The above embodiments are merely descriptions of specific implementation methods of the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and changes based on the prior art. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A rosin-type flux for indium-based low-temperature solder paste, characterized in that: The weight percentage of the ingredients is: 40-60wt.% of modified rosin, 2-5wt.% of organic acid activator, 0.5-2wt.% of halogen-containing compound, 2-5wt.% of hydrogenated castor oil, 0.1-1wt.% of benzotriazole, 0.1-1wt.% of triethanolamine, 0.5-2wt.% of surfactant, 0.5-2wt.% of paraffin oil; the balance is organic solvent.

2. The rosin type flux for indium-based low-temperature solder paste according to claim 1, characterized in that: The modified rosin is one or a combination of hydrogenated rosin, polymerized rosin, KR-610 or KE-604 rosin.

3. The rosin type flux for indium-based low-temperature solder paste according to claim 1 or 2, characterized in that: The organic acid activator has an organic acid with 2 to 10 carbon atoms; The organic acid activator is one or a combination of oxalic acid, adipic acid, succinic acid and glutaric acid.

4. The rosin type flux for indium-based low-temperature solder paste according to any one of claims 1 to 3, characterized in that: The halogen-containing compound is an organic amine hydrohalide and / or a halide; The organic amine hydrohalide is one or a combination of diethylamine hydrochloride, diethylamine hydrobromide, dimethylamine hydrochloride or triethylamine hydrochloride; The halogenated compound is one of dibromoethylbenzene and dibromobutylene glycol or a combination of several thereof.

5. The rosin type flux for indium-based low-temperature solder paste according to claim 4, characterized in that: The mass ratio of the organic acid activator to the halogen-containing compound is 1:0.2-0.

5.

6. The rosin type flux for indium-based low-temperature solder paste according to claim 5, characterized in that: The mass ratio of the organic acid activator to the organic amine hydrohalide is 1:0.2-0.3, and the mass ratio of the organic acid activator to the halide is 1:0.1-0.

2.

7. The rosin type flux for indium-based low-temperature solder paste according to claim 1, characterized in that: The surfactant is a nonionic surfactant; The surfactant is one of the fluorinated surfactants FSN-100, OP-10, and polyethylene oxide polypropylene oxide monobutyl ether, or a combination of several of them.

8. The rosin type flux for indium-based low-temperature solder paste according to claim 1, characterized in that: The organic solvent is a combination of fatty ether and fatty alcohol.

9. The rosin-type flux for indium-based low-temperature solder paste according to claim 1, wherein the organic solvent is one or a combination of triethylene glycol monobutyl ether, tetraethylene glycol dimethyl ether, propylene glycol, and hexylene glycol.

10. A method for preparing the indium-based solder low-temperature soldering flux according to claim 1, characterized in that: Add modified rosin, organic acid activator and benzotriazole into an organic solvent, stir and dissolve at 100-120°C for 1-1.5 hours; then add hydrogenated castor oil, stir and dissolve at 70-90°C for 0.45-0.55 hours; finally add halogenated compounds, surfactants and triethanolamine, stir and dissolve at 50-70°C for 1-2 hours; cool naturally and let stand for more than 12 hours to obtain the flux.

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