Flux paste for solder paste

Abstract

The invention relates to flux paste for solder paste. The flux paste for the solder paste comprises, by mass, 33%-50% of compound rosin, 1%-5% of a phosphite corrosion inhibitor, 4%-8% of a thixotropic agent, 3%-8% of a compound active agent, 0.4%-3% of a sulfonic acid active agent, 25%-40% of an organic solvent and 1%-6% of other auxiliaries. The phosphite ester corrosion inhibitor is one or more of tris (2, 4-di-tert-butylphenyl) phosphite ester, tri-iso-octyl phosphite ester, tribenzyl phosphite ester, dibutyl phosphite ester, dioctyl phosphite ester and trioctyl phosphite ester. The sulfonic acid active agent is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine sulfamate, p-toluenesulfonic anhydride and 1-phenyl sulfonyl pyrrole. The invention further discloses a preparation method of the flux paste for the solder paste. Good printing stability, welding effect and nickel-based bonding pad expansion rate are realized at the same time on the whole.

Description

Technical Field

[0001] The present application relates to a solder paste, which is mainly suitable for welding of printed circuit boards, and is particularly suitable for welding containing nickel-based metals. Background Art

[0002] China invention application publication CN202210391985.X discloses a high-stability solder paste and a preparation method, wherein the solder paste contains 30-45wt.% of compound rosin, 3-10wt.% of compound thixotropic agent, 3-12wt.% of compound activator, 30-50wt.% of compound organic solvent, and 1-6wt.% of other additives. Although the product has good printing stability, it has a narrow application range, especially when facing nickel-based pads, the wetting effect is not good, resulting in poor welding effect. Summary of the invention

[0003] The technical problem solved by the present application is to overcome the above-mentioned deficiencies in the prior art and provide a solder paste having a wide range of applications and relatively good storage and printing stability.

[0004] The technical solution adopted by the present application to solve the above technical problems includes: a solder paste for soldering, wherein the mass ratio of the solder paste for soldering is 33-50% of compound rosin, 1-5% of phosphite corrosion inhibitor, 4-8% of thixotropic agent, 3-8% of compound active agent, 0.4-3% of sulfonic acid active agent, 25-40% of organic solvent, and 1-6% of other auxiliary agents. The present application uses a proper proportion of sulfonic acid active agent in combination with phosphite corrosion inhibitor, which is beneficial to welding on the basis of effectively protecting tin powder, and the overall composition ratio is beneficial to achieving good printing stability, welding effect, and nickel-based pad expansion rate at the same time.

[0005] The compound rosin is compounded by crystallized rosin, non-crystallized rosin and rosin ester, and the ratio of the three rosins is: (1-1.2): (1-1.2): (0.2-0.3), and the diameter of the compound rosin is not greater than 10 mm; the acid value of the crystallized rosin is between 100 and 180; the acid value of the non-crystallized rosin is greater than 220; and the acid value of the rosin ester is less than 10.

[0006] The phosphite corrosion inhibitor is a compound of one or more of a plurality of phosphites, such as tris(2,4-di-tert-butylphenyl)phosphite, triisooctylphosphite, tribenzylphosphite, dibutylphosphite, dioctylphosphite and trioctylphosphite.

[0007] The thixotropic agent is prepared by compounding one or more of fatty acid amide, modified hydrogenated castor oil and polyamide wax.

[0008] The composite active agent is a mixture of multiple organic acids, generally a long-chain diacid, and the carbon chain length thereof is C4-C12.

[0009] The sulfonic acid active agent is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine sulfamate, p-toluenesulfonic anhydride, and 1-phenylsulfonyl pyrrole.

[0010] The organic solvent is prepared by compounding 1 to 3 solvents, including diethylene glycol hexyl ether, diethylene glycol, triethylene glycol, tetraethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and tripropylene glycol butyl ether. Other additives include: one or more of benzotriazole corrosion inhibitors, hindered phenol antioxidants, and surfactants.

[0011] The technical solutions adopted by this application to solve the above technical problems also include: The method for preparing the solder paste flux paste is characterized by comprising the following steps: S1: Break the solid rosin into pieces with a diameter not exceeding 10 mm, and then add them in proportion; then add the organic solvents in sequence, heat and stir until the rosin is completely dissolved; S2: Add phosphite corrosion inhibitor and thixotropic agent in sequence, heat and stir to completely dissolve them; S3: Add the compound active agent, sulfonic acid active agent and other additives in sequence, heat and stir to completely dissolve them; S4: Rapidly cool to room temperature.

[0012] Compared with the prior art, the present invention has the following advantages and effects: wide application range and good storage and printing stability. DETAILED DESCRIPTION

[0013] The component mass ratio of the solder paste for solder paste in this application is 33-50% of compound rosin, 1-5% of phosphite corrosion inhibitor, 4-8% of thixotropic agent, 3-8% of compound activator, 0.4-3% of sulfonic acid activator, 25-40% of organic solvent, and 1-6% of other additives. In the above formula, the sulfonic acid activator can quickly remove the oxide film when facing the nickel-based pad, which is beneficial to welding; at the same time, the phosphite corrosion inhibitor can effectively protect the tin powder, so that it can achieve good printing stability.

[0014] The compound rosin is compounded from crystalline rosin, non-crystalline rosin and rosin ester. The ratio of the three kinds of rosin is generally: (1-1.2): (1-1.2): (0.2-0.3). The rosin needs to be broken before use, and no large pieces with a diameter greater than 10 mm are allowed.

[0015] The acid value of the crystallized rosin is generally between 100 and 180; the acid value of the non-crystallized rosin is generally greater than 220; and the acid value of the rosin ester is less than 10.

[0016] The phosphite corrosion inhibitor is a compound of one or more of a plurality of phosphites, such as tris(2,4-di-tert-butylphenyl)phosphite, triisooctylphosphite, tribenzylphosphite, dibutylphosphite, dioctylphosphite and trioctylphosphite.

[0017] The thixotropic agent is prepared by compounding one or more of fatty acid amide, modified hydrogenated castor oil and polyamide wax.

[0018] The composite active agent is a mixture of multiple organic acids, generally a long-chain diacid, and the carbon chain length thereof is C4-C12.

[0019] The sulfonic acid active agent is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine sulfamate, p-toluenesulfonic anhydride, and 1-phenylsulfonyl pyrrole.

[0020] The organic solvent is prepared by compounding 1 to 3 solvents, including diethylene glycol hexyl ether, diethylene glycol, triethylene glycol, tetraethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and tripropylene glycol butyl ether. Other additives include: one or more of benzotriazole corrosion inhibitors, hindered phenol antioxidants, and surfactants.

[0021] The present application is further described in detail below through examples. The following examples are for explanation of the present application and the present application is not limited to the following examples.

[0022] The following experiments mainly changed the dosage of sulfonic acid substances and correspondingly changed the dosage of phosphate substances to achieve the best overall effect.

[0023] Table 1 Component ratios of examples and comparative examples Table 2 Comparison of technical effects of embodiments and comparative examples Effect description: Through experimental testing, it can be seen that the effects of the comparative example and the embodiment are quite different. The main reasons for this difference are two points: 1) Sulfonic acid substances have a strong ability to remove metal oxides, which can better achieve the wetting of tin-based metals on the nickel-based surface. At the same time, they also have a certain degree of corrosiveness to the tin-based metal surface, affecting the corrosion effect of the copper plate; 2) Phosphite substances have a good corrosion inhibition effect on metals (especially tin-based metals) and are highly efficient metal corrosion inhibitors that can form a protective film on the metal surface. Therefore, they have good effects in copper plate corrosion experiments and continuous printing experiments.

[0024] The expansion rate of nickel-plated sheet in this application: 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. Solder paste flux paste, its characteristics are: The solder paste flux paste has the following components in mass ratio: 33-50% of compound rosin, 1-5% of phosphite corrosion inhibitor, 4-8% of thixotropic agent, 3-8% of compound activator, 0.4-3% of sulfonic acid activator, 25-40% of organic solvent and 1-6% of other auxiliary agents.

2. The solder paste according to claim 1, wherein: The compound rosin is compounded by crystallized rosin, non-crystallized rosin and rosin ester, and the ratio of the three rosins is: (1-1.2): (1-1.2): (0.2-0.3), and the diameter of the compound rosin is not greater than 10 mm; the acid value of the crystallized rosin is between 100 and 180; the acid value of the non-crystallized rosin is greater than 220; and the acid value of the rosin ester is less than 10.

3. The solder paste according to claim 1, wherein: The phosphite corrosion inhibitor is one or more of tris(2,4-di-tert-butylphenyl)phosphite, triisooctylphosphite, tribenzylphosphite, dibutylphosphite, dioctylphosphite and trioctylphosphite.

4. The solder paste according to claim 1, wherein: The thixotropic agent is one or more of fatty acid amide, modified hydrogenated castor oil and polyamide wax.

5. The solder paste according to claim 1, wherein: The composite active agent is prepared by mixing a plurality of long-chain diacid organic acids, and the carbon chain length of the organic acid is C4-C12.

6. The solder paste according to claim 1, characterized in that: The sulfonic acid active agent is one or more of hexane sulfonate, methanesulfonic anhydride, guanidine sulfamate, p-toluenesulfonic anhydride, and 1-phenylsulfonyl pyrrole.

7. The 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.

8. The solder paste according to claim 1, wherein: The other auxiliary agents are one or more of benzotriazole corrosion inhibitors, hindered phenol antioxidants, and surfactants.

9. The solder paste according to claim 1, characterized in that: The expansion rate of the nickel-plated sheet for solder paste is 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.

10. The method for preparing the solder paste according to any one of claims 1 to 9, characterized in that The following steps are involved: S1: crush the compound rosin into pieces with a diameter no larger than 10 mm and add them in proportion, then add the organic solvents in sequence and heat and stir until the compound rosin is completely dissolved; S2: Add phosphite corrosion inhibitor and thixotropic agent in sequence, heat and stir to completely dissolve them; S3: Add the compound active agent, sulfonic acid active agent and other additives in sequence, heat and stir to completely dissolve them; S4: Rapidly cool to room temperature.

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