A soldering paste for solder paste

Abstract

The application relates to a soldering flux for tin paste, and the component mass ratio of the soldering flux for tin paste is as follows: compounded rosin 33-50%, phosphite corrosion inhibitor 1-5%, thixotropic agent 4-8%, compounded active agent 3-8%, sulfonic acid active agent 0.4-3%, organic solvent 25-40%, and other additives 1-6%. The phosphite corrosion inhibitor is one or more of tri (2, 4-di-tert-butylphenyl) phosphite, triisooctyl phosphite, tribenzyl phosphite, dibutyl phosphite, dioctyl phosphite and trioctyl phosphite. The sulfonic acid active agent is one or more of sulfonic acid hexane, methyl sulfonic anhydride, guanidine sulfamic acid, p-toluene sulfonic anhydride and 1-phenyl sulfonic acid pyrrole. The application also includes a preparation method of the soldering flux for tin paste. The application simultaneously realizes good printing stability, welding effect and nickel-based pad expansion rate.

Description

Technical Field

[0001] This application relates to a solder paste for soldering, which is mainly suitable for soldering printed circuit boards, and is especially suitable for soldering containing nickel-based metals. Background Technology

[0002] Chinese invention application publication CN202210391985.X discloses a high-stability solder paste and its preparation method. The solder paste comprises 30-45 wt.% compounded rosin, 3-10 wt.% compounded thixotropic agent, 3-12 wt.% compounded activator, 30-50 wt.% compounded organic solvent, and 1-6 wt.% other additives. While this product exhibits good printing stability, its application range is relatively narrow, especially when dealing with nickel-based pads, where poor wetting results lead to unsatisfactory soldering performance. Summary of the Invention

[0003] The technical problem solved by this application is to overcome the above-mentioned deficiencies in the prior art and to provide a solder paste with wide applicability and good storage and printing stability.

[0004] The technical solution adopted by this application to solve the above-mentioned technical problems includes: a solder paste for soldering, wherein the solder paste for soldering has the following component mass ratio: 33-50% compound rosin, 1-5% phosphite corrosion inhibitor, 4-8% thixotropic agent, 3-8% compound activator, 0.4-3% sulfonic acid activator, 25-40% organic solvent, and 1-6% other additives. This application uses an appropriate proportion of sulfonic acid activator combined with phosphite corrosion inhibitor, which effectively protects the solder powder and facilitates soldering. The overall component ratio is conducive to simultaneously achieving good printing stability, soldering effect, and nickel-based pad expansion rate.

[0005] The compound rosin is composed of crystalline rosin, non-crystalline rosin, and rosin esters, with the ratio of the three rosins being (1-1.2):(1-1.2):(0.2-0.3). The diameter of the compound rosin is no greater than 10 mm. The acid value of the crystalline rosin is between 100 and 180. The acid value of the non-crystalline rosin is greater than 220. The acid value of the rosin ester is less than 10.

[0006] The phosphite corrosion inhibitor is one or more of a variety of phosphites, such as tris(2,4-di-tert-butylphenyl) phosphite, triisooctyl phosphite, tribenzyl phosphite, dibutyl phosphite, dioctyl phosphite, and trioctyl phosphite.

[0007] The thixotropic agent is composed of one or more of fatty acid amides, modified hydrogenated castor oil, and polyamide wax.

[0008] The compound activator is composed of a mixture of various organic acids, generally long-chain diacids with a carbon chain length of C4-C12.

[0009] The sulfonic acid surfactant is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine aminosulfonate, p-toluenesulfonic anhydride, and 1-phenylsulfonic acid pyrrole.

[0010] The organic solvent is a compound of 1-3 solvents, including diethylene glycol hexyl ether, diethylene glycol, triethylene glycol, tetraethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and tripropylene glycol butyl ether.

[0011] Other additives include one or more of the following: benzotriazole corrosion inhibitors, hindered phenolic antioxidants, and surfactants.

[0012] The technical solution adopted in this application to solve the above-mentioned technical problems also includes: The method for preparing the above-mentioned flux for solder paste is characterized by including the following steps: S1: Crush large solid rosin pieces to a diameter of no more than 10mm, then add them in proportion; then add organic solvents in sequence, heat and stir until the rosin is completely dissolved; S2: Add phosphite corrosion inhibitor and thixotropic agent in sequence, and heat and stir until completely dissolved; S3: Add the compound surfactant, sulfonic acid surfactant, and other additives in sequence, and heat and stir until completely dissolved; S4: Quickly cool to room temperature.

[0013] Compared with the prior art, this application has the following advantages and effects: it has a wide range of applications and good storage and printing stability. Detailed Implementation

[0014] The flux for solder paste in this application comprises, by mass ratio: 33-50% compound rosin, 1-5% phosphite corrosion inhibitor, 4-8% thixotropic agent, 3-8% compound activator, 0.4-3% sulfonic acid activator, 25-40% organic solvent, and 1-6% other additives. In this formulation, the sulfonic acid activator can quickly remove the oxide film on nickel-based pads, which is beneficial for soldering; simultaneously, the phosphite corrosion inhibitor can effectively protect the solder powder, enabling it to achieve good printing stability.

[0015] The compound rosin is composed of crystalline rosin, non-crystalline rosin, and rosin esters. The ratio of the three rosins is generally (1-1.2):(1-1.2):(0.2-0.3). It must be crushed before use and there should be no large pieces with a diameter greater than 10mm.

[0016] The acid value of crystalline rosin is generally between 100 and 180; the acid value of non-crystalline rosin is generally greater than 220; and the acid value of rosin ester is less than 10.

[0017] The phosphite corrosion inhibitor is one or more of a variety of phosphites, such as tris(2,4-di-tert-butylphenyl) phosphite, triisooctyl phosphite, tribenzyl phosphite, dibutyl phosphite, dioctyl phosphite, and trioctyl phosphite.

[0018] The thixotropic agent is composed of one or more of fatty acid amides, modified hydrogenated castor oil, and polyamide wax.

[0019] The compound activator is composed of a mixture of various organic acids, generally long-chain diacids with a carbon chain length of C4-C12.

[0020] The sulfonic acid surfactant is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine aminosulfonate, p-toluenesulfonic anhydride, and 1-phenylsulfonic acid pyrrole.

[0021] The organic solvent is a compound of 1-3 solvents, including diethylene glycol hexyl ether, diethylene glycol, triethylene glycol, tetraethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and tripropylene glycol butyl ether.

[0022] Other additives include one or more of the following: benzotriazole corrosion inhibitors, hindered phenolic antioxidants, and surfactants.

[0023] The present application will be further described in detail below through embodiments. The following embodiments are explanations of the present application, but the present application is not limited to the following embodiments.

[0024] The following experiments mainly changed the amount of sulfonic acid substances, and correspondingly changed the amount of phosphate ester substances to achieve the best overall effect.

[0025]

[0026]

[0027] Results Explanation: Experimental tests show a significant difference in results between the comparative and the example samples. There are two main reasons for this difference: Sulfonic acids have a strong ability to remove metal oxides and can effectively wet tin-based metals on nickel-based surfaces. However, they also have a certain degree of corrosivity to tin-based metal surfaces, which affects the corrosion effect of copper plates. Phosphite esters have a good corrosion inhibition effect on metals (especially tin-based metals) and are highly efficient metal corrosion inhibitors. They can form a protective film on the metal surface, so they have good results in copper plate corrosion experiments and continuous printing experiments.

[0028] The nickel plating elongation rate of this application is greater than 73.5%; Continuous printing time: not less than 24 hours (printing speed 6 pieces / minute); Copper plate corrosion: No corrosion, L grade.

Claims

1. A flux for solder paste, characterized in that: The solder paste is suitable for soldering nickel-based metals. The solder paste comprises, by mass ratio, 33-50% compound rosin, 1-3% phosphite corrosion inhibitor, 4-8% thixotropic agent, 3-8% compound activator, 1-2% sulfonic acid activator, 25-40% organic solvent, and 1-6% other additives. The phosphite corrosion inhibitor is one or more of tris(2,4-di-tert-butylphenyl) phosphite, triisooctyl phosphite, tribenzyl phosphite, dibutyl phosphite, dioctyl phosphite, and trioctyl phosphite. The sulfonic acid activator is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine aminosulfonate, p-toluenesulfonic anhydride, and 1-phenylsulfonic acid pyrrole. The other additives are one or more of benzotriazole corrosion inhibitors, hindered phenolic antioxidants, and surfactants.

2. The solder paste for solder paste according to claim 1, characterized in that: The compound rosin is composed of crystalline rosin, non-crystalline rosin, and rosin esters, with the mass ratio of the three rosins being (1-1.2):(1-1.2):(0.2-0.3).

3. The flux for solder paste according to claim 1, characterized in that: The thixotropic agent is one or more of fatty acid amides, modified hydrogenated castor oil, and polyamide wax.

4. The flux for solder paste according to claim 1, characterized in that: The compound activator is composed of a mixture of various long-chain diacid organic acids, with the carbon chain length of the organic acids being C4-C12.

5. The solder paste for solder paste according to any one of claims 1 to 4, characterized in that: The organic solvent is one or more of diethylene glycol hexyl ether, diethylene glycol, triethylene glycol, tetraethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and tripropylene glycol butyl ether.

6. The flux for solder paste according to claim 1, characterized in that: The solder paste used for soldering has a nickel plating sheet expansion rate greater than 73.5%; the continuous printing time is not less than 24 hours when the printing speed is 6 sheets / minute; and the copper plate corrosion index reaches the non-corrosion L level.

7. The method for preparing solder paste according to any one of claims 1 to 6, characterized in that: Includes the following steps: S1: Crush the compound rosin to a diameter of no more than 10mm and add it in proportion. Then add the organic solvent in sequence, heat and stir until the compound rosin is completely dissolved. S2: Add phosphite corrosion inhibitor and thixotropic agent in sequence, and heat and stir until completely dissolved; S3: Add the compound surfactant, sulfonic acid surfactant, and other additives in sequence, and heat and stir until completely dissolved; S4: Rapidly cool to room temperature.

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