A leaded solder paste flux for a photovoltaic nickel substrate and its preparation method

Abstract

A leaded solder paste flux for a photovoltaic nickel substrate and a preparation method thereof. By weight percentage, the flux is composed of 38-45% of a compound rosin, 6-8% of a compound thixotropic agent, 6-8% of a compound organic acid, 3-5% of a whitening agent, 8-9% of a compound tackifier, 0.2-0.6% of a compound organic halogen activator, 0.5-0.8% of an antioxidant, and the balance of a compound solvent. Heat and stir the compound rosin, compound thixotropic agent, whitening agent, antioxidant, compound tackifier and compound solvent until melted at 170-172 °C, cool down to 153-157 °C, then add a macromolecular compound organic carboxylic acid and an ionic organic halogen activator, and then cool down to 145-147 °C and add a covalent organic halogen activator. Keep stirring at a constant temperature of 140-145 °C until completely dissolved and well mixed to prepare the flux. The flux of the present invention has high activity, good wettability for nickel-plated plate welding, good anti-collapse performance, good build-up height, less residue, and good anti-drying performance, and can ensure the reliability after welding.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic soft soldering materials, and particularly relates to a solder paste flux and a preparation method thereof. Background Art

[0002] With the development of solar photovoltaic power generation, the development space of photovoltaics is huge. Special fluxes for the photovoltaic industry are essential raw materials in the manufacturing process of photovoltaic devices. Due to the particularity of the substrate material and working environment of photovoltaic devices, extremely high requirements are imposed on the performance of soldering fluxes for welding, and fluxes in the ordinary electronics industry cannot meet the requirements. Most substrates of photovoltaic devices are nickel-based, and nickel substrates are difficult to weld. It is required that the solder joints after welding are bright, plump, have good stacking height, less residue, and light color. Therefore, leaded solder pastes for nickel substrates in photovoltaics should have the characteristics of good wettability, small slump and residual flow. At present, the leaded photovoltaic solder pastes on the market have insufficient stacking height for nickel-based substrates, there is a small amount of shrinkage in the solder joints, and the solder paste is prone to drying due to too high activity. Summary of the Invention

[0003] The purpose of the present invention is to solve the welding problem of nickel substrates in photovoltaics, and to provide a leaded solder paste flux for nickel substrates in photovoltaics with good weldability and stacking height, and a preparation method thereof, which meet the requirements of the solder paste flux for nickel substrate welding.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A leaded solder paste flux for nickel substrates in photovoltaics, by weight percentage, the raw material composition is:

[0006] Compound rosin 38.0 - 45.0%,

[0007] Compound thixotropic agent 6.0 - 8.0%,

[0008] Compound organic acid 6.0 - 8.0%,

[0009] Whitening agent 3033 3.0 - 5.0%,

[0010] Compound tackifier 6.0 - 8.0%,

[0011] Compound organic halogen activator 0.2 - 0.6%,

[0012] Antioxidant 0.5 - 0.8%,

[0013] Compound solvent the balance;

[0014] The compounded rosin is composed of high acid value rosin, medium acid value rosin and non-acid value rosin compounded according to a mass ratio of approximately 2:1:1; the high acid value rosin is one of 685 rosin and HM-604 rosin; the fully hydrogenated rosin is one of Eastman AX-E and AX-80; the non-acid value rosin resin is one of P100D resin, CH-60 rosin and KE-100 rosin;

[0015] The compounded thixotropic agent is composed of amide thixotropic agent SH and hydrogenated castor oil thixotropic agent compounded according to a mass ratio of 1:2;

[0016] The compounded organic acid is a mixture of two or more of macromolecular organic acids containing benzene rings, such as p-hydroxyphenylacetic acid, p-hydroxybenzoic acid, phenylsuccinic acid and phthalic acid;

[0017] The antioxidant is one of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 3-salicylamido-1,2,4-triazole;

[0018] The compounded solvent is a mixture of high boiling point solvents, namely diethylene glycol hexyl ether, triethylene glycol monobutyl ether and diethylene glycol octyl ether.

[0019] Furthermore, the high acid value rosin is one of 685 rosin and HM-604 rosin; the fully hydrogenated rosin is one of Eastman AX-E and AX-80; the rosin ester is one of P100D resin, CH-60 rosin and KE-100 rosin.

[0020] Furthermore, the compounded tackifier is two of glycerol, HV300, tetrapropyl ethylene diamine and polyvinylpyrrolidone K15. The use of this compounded tackifier can not only enhance the viscosity of the solder paste but also reduce the skinning and drying of the solder paste surface.

[0021] Furthermore, the compounded organic halogen activator is compounded from a covalent organic halogen activator and a free organic halogen activator. The covalent organic halogen activator is one or two of chlorendic anhydride, 2,3-dibromobutenediol and 2,3-dibromosuccinic acid; the free organic halogen activator is one or two of ethylenediamine hydrochloride, cyclohexylamine hydrochloride and diphenylguanidine hydrobromide. The compounding of the free organic halogen activator and the covalent organic halogen activator can ensure the weldability and build-up height of the photovoltaic nickel-based material.

[0022] The preparation method of the leaded solder paste flux for the photovoltaic nickel-based board of the present invention includes the following steps:

[0023] (1) Add the compounded rosin, compounded thixotropic agent, whitening agent, compounded tackifier, antioxidant and compounded solvent into a reactor, heat to 170 - 172 °C and stir until completely melted to obtain mixed solution 1;

[0024] (2) Cooling the mixed solution 1 to 153-157°C, adding the composite organic carboxylic acid and the free organic halogen activator, stirring and melting to obtain a mixed solution 2;

[0025] (3) The mixed solution 2 is cooled to 145-147°C, a covalent organic halogen activator is added, and the mixture is stirred to dissolve and mix evenly. The mixture is stirred at 140-145°C, and the mixture is sealed and placed in a refrigerator at 2-8°C for 4 hours. The mixture is then taken out and placed at room temperature for 4 hours to prepare the soldering flux.

[0026] The present invention has the following advantages:

[0027] (1) The use of a compound tackifier is one of the characteristics of the present invention. The present invention uses two or three of glycerol, HV300, tetrahydroxypropylethylenediamine, and polyvinylpyrrolidone K15 in a compound. On the one hand, the viscosity of the solder paste is improved to ensure the printability of the solder paste and prevent the solder paste from forming a skin on the surface. On the other hand, the addition of the tackifier can adhere to the surface of the spherical solder powder to form a protective film to protect the solder powder from being corroded by free organic halides such as cyclohexylamine hydrochloride, ethylenediamine hydrochloride, and diphenylguanidine hydrobromide.

[0028] (2) The present invention uses an organic halogen activator compounded with a covalent organic halogen activator and a free organic halogen activator to ensure the activity of the flux formula. Most photovoltaic solder strips are nickel-based with poor solderability and require highly active flux for welding. Adding organic acid helps to improve the activity of the flux, but adding too much organic acid will increase the acid value of the flux, aggravate the corrosion of lead solder powder, and increase the risk of drying out. By using covalent and ionic organic halogen activators for compounding, on the one hand, the free organic halogen activators cyclohexylamine hydrochloride and diphenylguanidine hydrobromide provide activity when welding nickel-based, ensuring the solderability of solder paste; on the other hand, compared with the free organic halogen activator, the activity of the covalent organic halogen activator is relatively mild, 2,3-dibromobutenediol can keep the solder paste moist and reduce the crusting of the solder paste, and chlorohydric anhydride has a good improvement effect on the drying out of the solder paste. With the use of a tackifier, the compounded organic halogen activator has good stability. The use of compounded organic halogen activators can reduce the amount of organic acid used. Combined with the added antioxidants, it can effectively reduce the corrosion of the flux on the Sn-Pb solder joints, greatly improving the drying problem of the solder paste.

[0029] (3) The solder paste flux formula of the present invention has high activity and is suitable for Sn-Pb series solders. It has good wettability after welding, bright and full solder joints, less collapse, good pile height, small residue flow, low corrosion, high insulation resistance, and a spreading rate of more than 90%. It can be applied to the spot coating and printing processes of photovoltaic nickel substrates by adjusting the flux ratio. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below by way of examples.

[0031] Example 1

[0032] A leaded solder paste flux for photovoltaic nickel substrates, with its components and mass percentages as follows:

[0033]

[0034] The preparation method of the leaded solder paste flux for photovoltaic nickel substrates is as follows: Add HM-604 rosin, AX-E rosin, CH-60 rosin, thixotropic agent SH, hydrogenated castor oil, whitening agent 3033, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, glycerol, tetrahydroxypropyl ethylenediamine, diethylene glycol hexyl ether, triethylene glycol monobutyl ether, and diethylene glycol octyl ether into a reactor, heat for about 20 min to 170 - 172 °C and stir until completely melted, cool down to about 155 °C in about 5 - 6 min, add p-hydroxybenzeneacetic acid, phthalic acid, and cyclohexylamine hydrochloride, stir for 3 - 4 minutes until completely melted, add dichloromaleic anhydride and 2,3-dibromobutenediol at 145 °C, keep the temperature at 140 - 145 °C and stir constantly for 3 minutes to completely dissolve and mix the components evenly, end at 140 °C, and quickly seal and put it in a refrigerator at 2 - 8 °C for refrigeration for 4 hours, take it out and let it return to room temperature for 4 hours to prepare the leaded solder paste flux for photovoltaic nickel substrates.

[0035] Mix the flux of this example with Sn63Pb37 4a solder powder according to a 10% ratio and stir to prepare a solder paste, and conduct viscosity, wettability, centrifugal stability, copper plate corrosion, and surface insulation resistance tests after soldering respectively. The test results are shown in Table 1.

[0036] Example 2

[0037] A leaded solder paste flux for photovoltaic nickel substrates, with its components and mass percentages as follows:

[0038]

[0039] The preparation method of the leaded solder paste flux for photovoltaic nickel substrates is as follows: Add 685 rosin, AX-80 rosin, 100D rosin, thixotropic agent SH, hydrogenated castor oil, brightening agent 3033, 3-salicylamido-1,2,4-triazole, glycerol, polyvinylpyrrolidone K15, diethylene glycol hexyl ether, triethylene glycol monobutyl ether, and diethylene glycol octyl ether into the reactor. Heat for about 20 min to 170 - 172 °C and stir until completely melted. Then cool down to 153 °C in about 5 - 6 min. Add p-hydroxybenzoic acid, phenylsuccinic acid, and ethylenediamine hydrochloride, and stir for 3 - 4 minutes until completely melted. Add dichloromaleic anhydride at 146 °C, keep the temperature at 140 - 145 °C and stir constantly for 3 minutes to completely dissolve and mix the components evenly. End at 142 °C, quickly seal and put it in a refrigerator at 2 - 8 °C for refrigeration for 4 hours. Take it out and let it warm up at room temperature for 4 hours to prepare the leaded solder paste flux for photovoltaic nickel substrates.

[0040] Mix the flux of this example with Sn63Pb37 4a solder powder according to the ratio of 10% ± 0.5 and stir to prepare solder paste. Conduct viscosity, wettability, centrifuge stability, copper plate corrosivity, and surface insulation resistance after soldering tests respectively. The test results are shown in Table 1.

[0041] Example 3

[0042] A leaded solder paste flux for photovoltaic nickel substrates, its components and mass percentages are as follows:

[0043]

[0044] The preparation method of the leaded solder paste flux for photovoltaic nickel substrates is as follows: Add 685 rosin, AX-E rosin, KE-100 rosin, thixotropic agent SH, hydrogenated castor oil, brightening agent 3030, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, glycerol, HV300, diethylene glycol hexyl ether, triethylene glycol monobutyl ether, and diethylene glycol octyl ether into the reactor. Heat for about 20 min to 170 °C and stir until completely melted. Then cool down to 157 °C in about 5 min. Add p-hydroxyphenylacetic acid, phthalic acid, and ethylenediamine hydrochloride, and stir for 3 - 4 minutes until completely melted. Add dichloromaleic anhydride and 2,3-dibromosuccinic acid at 147 °C, keep the temperature at 140 - 145 °C and stir constantly for 3 minutes to completely dissolve and mix the components evenly. End at 140 °C, quickly seal and put it in a refrigerator at 2 - 8 °C for refrigeration for 4 hours. Take it out and let it warm up at room temperature for 4 hours to prepare the leaded solder paste flux for photovoltaic nickel substrates.

[0045] Mix the soldering flux of this embodiment with Sn63Pb37 4a solder powder at a ratio of 10% ± 0.5, stir and mix them to prepare solder paste, and conduct tests on viscosity, wettability, centrifugal stability, copper plate corrosion, and surface insulation resistance after soldering respectively. The test results are shown in Table 1.

[0046] Example 4

[0047] A leaded solder paste flux for photovoltaic nickel substrates, its components and mass percentages are as follows:

[0048]

[0049] The preparation method of the leaded solder paste flux for photovoltaic nickel substrates is as follows: Add 685 rosin, AX-80 rosin, CH-60 rosin, thixotropic agent SH, hydrogenated castor oil, brightening agent 3030, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, glycerol, polyvinylpyrrolidone K15, diethylene glycol hexyl ether, triethylene glycol monobutyl ether, and diethylene glycol octyl ether into the reactor, heat for about 20 minutes to 170 °C and stir until completely melted, and cool down to about 156 °C in about 5 minutes. Then add phenylsuccinic acid, p-hydroxyphenylacetic acid, cyclohexylamine hydrochloride, and diphenylguanidine hydrobromide, stir for 3 - 4 minutes until completely melted, add chlorendic anhydride at 145 °C, keep the temperature at 140 - 145 °C and stir constantly for 3 minutes to completely dissolve and mix the components evenly, end at 142 °C, and quickly seal and put it in a refrigerator at 2 - 8 °C for refrigeration for 4 hours. Take it out and let it warm up at room temperature for 4 hours to prepare the leaded solder paste flux for photovoltaic nickel substrates.

[0050] Mix the soldering flux of this embodiment with Sn63Pb37 4a solder powder at a ratio of 10% ± 0.5 according to a certain stirring process to prepare solder paste, and conduct tests on viscosity, wettability, centrifugal stability, copper plate corrosion, and surface insulation resistance after soldering respectively. The test results are shown in Table 1.

[0051] According to the relevant test methods specified in the international standard IPC-TM-650, conduct tests on wettability, slump, spread rate, centrifugal stability, copper plate corrosion, and surface insulation resistance after soldering for the above embodiments respectively. The test results are shown in Table 1.

[0052] Table 1 Performance Detection List of Flux for Solder Paste

[0053]

[0054] As can be seen from Table 1, the halogen content of the flux of the present invention is all of type L, which is applicable to Sn-Pb series solders. After soldering, it has good wettability, bright and plump solder joints, less slump, good heap height, small residue flow, low corrosion, high insulation resistance, a spread rate of more than 90%, and a surface insulation resistance greater than 109 Ω, meeting the requirement that the surface insulation resistance > 10 8 Ω in IPC-TM-650 international standard.

[0055] The above embodiments are only partial embodiments of the present invention and do not limit the protection scope of the present invention. The leaded solder paste flux for photovoltaic nickel substrates prepared according to the following raw materials and their ratio ranges all fall within the protection scope of the present invention:

[0056] Compound rosin 38.0 - 45.0%,

[0057] Compound thixotropic agent 6.0 - 8.0%,

[0058] Compound organic acid 6.0 - 8.0%,

[0059] Whitening agent 3033 3.0 - 5.0%,

[0060] Compound tackifier 6.0 - 8.0%,

[0061] Compound organic halogen activator 0.2 - 0.6%,

[0062] Antioxidant 0.5 - 0.8%,

[0063] Compound solvent the balance.

[0064] Unless otherwise specified, the percentages described in the present invention are all mass percentages.

Claims

1. A leaded solder paste flux for a photovoltaic nickel substrate, characterized in that: By weight percentage, the raw material composition is as follows: Compound rosin 38.0 - 45.0%, Compound thixotropic agent 6.0 - 8.0%, Compound organic acid 6.0 - 8.0%, Whitening agent 3033 3.0 - 5.0%, Compound tackifier 6.0 - 8.0%, Compound organic halogen activator 0.2 - 0.6%, Antioxidant 0.5 - 0.8%, Compound solvent the balance; The compound rosin is composed of high acid value rosin, fully hydrogenated rosin and rosin ester in a mass ratio of 2:1:1; The compound thixotropic agent is composed of amide thixotropic agent SH and hydrogenated castor oil thixotropic agent in a mass ratio of 1:2; The compound organic acid is a mixture of two or more of macromolecular organic acids containing benzene ring, such as p - hydroxy phenylacetic acid, p - hydroxy benzoic acid, phenyl succinic acid, phthalic acid; The antioxidant is one of octadecyl 3 - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate and 3 - salicylamido - 1,2,4 - triazole; The compound solvent is a mixture of high - boiling solvents, diethylene glycol hexyl ether, triethylene glycol monobutyl ether and diethylene glycol octyl ether; The compound organic halogen activator is composed of covalent organic halogen activator and free organic halogen activator. The covalent organic halogen activator is one or two of chlorendic anhydride, 2,3 - dibromobutenediol, 2,3 - dibromosuccinic acid; the free organic halogen activator is one or two of ethylenediamine hydrochloride, cyclohexylamine hydrochloride, diphenylguanidine hydrobromide.

2. The soldering flux for leaded solder paste used in a photovoltaic nickel substrate according to claim 1, characterized in that, The high acid value rosin is one of 685 rosin and HM - 604 rosin; the fully hydrogenated rosin is one of Eastman AX - E and AX - 80; the rosin ester is one of P100D resin, CH - 60 rosin and KE - 100 rosin.

3. The soldering flux for leaded solder paste used in a photovoltaic nickel substrate according to claim 1, characterized in that, The compound tackifier is two of glycerol, HV300, tetra - hydroxypropyl ethylenediamine and polyvinylpyrrolidone K15.

4. The preparation method of a leaded solder paste flux for a photovoltaic nickel substrate according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Add compound rosin, compound thixotropic agent, whitening agent, compound tackifier, antioxidant and compound solvent into a reactor, heat to 170 - 172 °C and stir until completely melted to obtain mixed solution 1; (2) Cool mixed solution 1 to 153 - 157 °C, then add compound organic carboxylic acid and free organic halogen activator, and stir until completely melted to obtain mixed solution 2; (3) Cool mixed solution 2 to 145 - 147 °C, add covalent organic halogen activator, stir well to dissolve and mix evenly, end at 140 - 145 °C, seal and put it in a refrigerator at 2 - 8 °C for 4 h, then take it out and place it at room temperature for 4 h to prepare the soldering flux.

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