High-stability spot-coating needle cylinder solder paste and preparation method thereof

Abstract

The invention discloses high-stability spot-coating needle cylinder solder paste and a preparation method thereof. The high-stability spot-coating needle cylinder solder paste is prepared from, by weight, 82.0%-88.0% of soldering tin powder, 3.5%-5.0% of hydrogenated rosin, 1.2%-2.0% of modified phenolic resin, 0.8%-1.5% of adipic acid, 0.5%-1.0% of diethylamine hydrobromide, 2.0%-3.5% of propylene glycol methyl ether acetate, 0.6%-1.2% of hydrogenated castor oil, 0.3%-0.8% of polyamide wax, 0.3%-0.8% of 2, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, 0.3%-0.8% of sodium hydroxide, 0.3%-0.8 the raw materials comprise, by weight, 0.1%-0.3% of 2, 6-butylated hydroxytoluene, 0.2%-0.5% of polyoxyethylene sorbitan monooleate, 0.3%-0.7% of fumed silica, 0.05%-0.15% of ethylene diamine tetraacetic acid disodium salt and 0.1%-0.3% of benzotriazole; through the synergistic effect of the soldering tin powder and the soldering flux, the spot coating performance of the needle cylinder solder paste is remarkably improved, tin output is stable in the continuous spot coating process, and the hole blocking rate is remarkably reduced. The antioxidant, the metal chelating agent and other components are added, oxidation and layering of the solder paste are effectively inhibited, the viscosity change rate is low after the solder paste is stored for 30 days, and the storage stability is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of solder materials for electronic manufacturing, specifically to a highly stable dot-applied syringe solder paste and its preparation method. Background Technology

[0002] In electronic manufacturing, syringe solder paste is a key material in surface mount technology, and its application performance and stability directly affect soldering quality and production efficiency. Existing syringe solder pastes suffer from the following problems: uneven solder dispensing and skipping during dispensing; high clogging rate during continuous dispensing; stability issues such as delamination, drying, and abnormal viscosity changes during storage; and insufficient solder joint strength and large fluctuations in conductivity after soldering, making it difficult to meet the soldering requirements of high-precision electronic components. Therefore, developing a highly stable syringe solder paste with stable solder dispensing, good storage properties, and excellent soldering quality has significant application value. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a highly stable dot-applied syringe solder paste and its preparation method, thus solving the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a highly stable dot-applied syringe solder paste, composed of the following components by weight percentage:

[0005] The composition includes: solder powder 82.0-88.0%, hydrogenated rosin 3.5-5.0%, modified phenolic resin 1.2-2.0%, adipic acid 0.8-1.5%, diethylamine hydrobromide 0.5-1.0%, propylene glycol methyl ether acetate 2.0-3.5%, hydrogenated castor oil 0.6-1.2%, polyamide wax 0.3-0.8%, 2,6-di-tert-butyl-p-cresol 0.1-0.3%, polyoxyethylene sorbitan monooleate 0.2-0.5%, fumed silica 0.3-0.7%, disodium ethylenediaminetetraacetate 0.05-0.15%, and benzotriazole 0.1-0.3%.

[0006] Preferably, it consists of the following components by weight percentage:

[0007] The composition includes 85.0% solder powder, 4.2% hydrogenated rosin, 1.6% modified phenolic resin, 1.1% adipic acid, 0.7% diethylamine hydrobromide, 2.8% propylene glycol methyl ether acetate, 0.9% hydrogenated castor oil, 0.5% polyamide wax, 0.2% 2,6-di-tert-butyl-p-cresol, 0.3% polyoxyethylene sorbitan monooleate, 0.5% fumed silica, 0.1% disodium ethylenediaminetetraacetate, and 0.2% benzotriazole.

[0008] Preferably, it consists of the following components by weight percentage:

[0009] The composition includes: solder powder 82.0%, hydrogenated rosin 5.0%, modified phenolic resin 2.0%, adipic acid 1.5%, diethylamine hydrobromide 1.0%, propylene glycol methyl ether acetate 3.5%, hydrogenated castor oil 1.2%, polyamide wax 0.8%, 2,6-di-tert-butyl-p-cresol 0.3%, polyoxyethylene sorbitan monooleate 0.5%, fumed silica 0.7%, disodium ethylenediaminetetraacetate 0.15%, and benzotriazole 0.3%.

[0010] Preferably, it consists of the following components by weight percentage:

[0011] The composition includes: 88.0% solder powder, 3.5% hydrogenated rosin, 1.2% modified phenolic resin, 0.8% adipic acid, 0.5% diethylamine hydrobromide, 2.0% propylene glycol methyl ether acetate, 0.6% hydrogenated castor oil, 0.3% polyamide wax, 0.1% 2,6-di-tert-butyl-p-cresol, 0.2% polyoxyethylene sorbitan monooleate, 0.3% fumed silica, 0.05% disodium ethylenediaminetetraacetate, and 0.1% benzotriazole.

[0012] The functions of each component in the raw material are as follows:

[0013] Solder powder: provides the metal matrix required for welding, ensuring the mechanical strength and conductivity of the solder joint. It is composed of tin, silver, copper and bismuth in a specific ratio and has a low melting point and high fluidity.

[0014] Hydrogenated rosin: As the main component of flux, it has good wettability, can remove the oxide layer on the metal surface, and promote solder spreading.

[0015] Modified phenolic resin: enhances the bonding strength of solder paste, improves the impact resistance of solder joints, and improves the film-forming properties of solder paste.

[0016] Adipic acid: As an organic acid activator, it helps remove metal oxide films and improves welding activity.

[0017] Diethylamine hydrobromide: An organic amine hydrohalide activator that enhances soldering performance, especially for copper substrates.

[0018] Propylene glycol methyl ether acetate: an environmentally friendly solvent that adjusts the viscosity of solder paste, ensuring smooth application during dotting, and promoting compatibility among components.

[0019] Hydrogenated castor oil: a thixotropic agent that imparts good thixotropic properties to solder paste, allowing it to flow well when applied and maintain its shape when left to stand, thus reducing collapse.

[0020] Polyamide wax: works synergistically with thixotropic agents to further optimize the rheological properties of solder paste and improve the stability of continuous dotting.

[0021] 2,6-Di-tert-butyl-p-cresol: An antioxidant that inhibits oxidation and deterioration of solder paste during storage and use, extending its shelf life.

[0022] Polyoxyethylene sorbitan monooleate: a nonionic surfactant that reduces interfacial tension, improves the compatibility of solder powder and flux, and reduces agglomeration.

[0023] Fumed silica: a thickener that adjusts the viscosity of solder paste, prevents solder powder from settling, and improves system stability.

[0024] Disodium EDTA: A metal chelating agent that forms stable chelates with metal ions, preventing catalytic oxidation reactions by metal ions and enhancing storage stability.

[0025] Benzotriazole: a corrosion inhibitor that protects metal surfaces, prevents subsequent corrosion of weld joints, and improves the long-term reliability of welded joints.

[0026] Preferably, the solder powder is composed of tin, silver, copper, and bismuth in a mass ratio of 96.5:3.0:0.3:0.2, with a particle size of 20-38 micrometers; the hydrogenated rosin has an acid value of 160-180 mgKOH / g and a softening point of 75-85℃; the modified phenolic resin has a molecular weight of 3000-5000 and a softening point of 90-100℃.

[0027] A method for preparing a highly stable dot-applied syringe solder paste includes the following steps:

[0028] Step 1: Solder powder preparation: Tin, silver, copper, and bismuth are added to a vacuum melting furnace at a mass ratio of 96.5:3.0:0.3:0.2. Under inert gas protection, the mixture is melted and mixed at 280-320℃ for 30-40 minutes to form an alloy melt. The melt is then atomized into powder using a gas atomization method at a pressure of 3-5 MPa. After cooling, solder powder with a particle size of 20-38 micrometers is screened out for later use.

[0029] Step 2, Raw material pretreatment: Dry hydrogenated rosin and modified phenolic resin separately in a vacuum drying oven at 60-70℃ for 2-3 hours; grind adipic acid and diethylamine hydrobromide to an 80-100 mesh sieve;

[0030] Step 3, Flux Preparation: Add propylene glycol methyl ether acetate to the reactor, heat to 40-50℃, stir at 200-300 rpm, add hydrogenated rosin and modified phenolic resin sequentially until dissolved; add adipic acid and diethylamine hydrobromide, stir for 15-20 minutes; add hydrogenated castor oil and polyamide wax, heat to 60-65℃, stir for 30-40 minutes; add 2,6-di-tert-butyl-p-cresol, polyoxyethylene sorbitan monooleate, fumed silica, disodium ethylenediaminetetraacetate, and benzotriazole, stir for 25-35 minutes to obtain the flux;

[0031] Step 4, Mixing: Add the solder powder from Step 1 and the flux from Step 3 to a double planetary mixer at a mass ratio of 85:15, and stir for 10-15 minutes at 500-600 rpm under nitrogen protection.

[0032] Step 5, Homogenization: Transfer the mixture to a high-shear homogenizer and homogenize at 3000-4000 rpm for 20-30 minutes;

[0033] Step 6, Degassing treatment: Degas the homogenized material for 15-20 minutes under vacuum conditions of -0.09 to -0.08 MPa and 30-35℃.

[0034] Step 7, Aging treatment: Aging the degassed material in a constant temperature chamber at 25-30℃ for 24-48 hours;

[0035] Step 8, Sieving and Filtration: Use a 100-120 mesh sieve for filtration;

[0036] Step 9, Filling: In a Class 1000 cleanroom environment, fill the syringe with a pressure of 0.2-0.3 MPa;

[0037] Step 10, Packaging: Sealed packaging with aluminum-plastic composite film, stored at 4-10℃.

[0038] Preferably, the inert gas in step 1 is nitrogen or argon, and the cooling medium for the gas atomization method is compressed air.

[0039] Preferably, the stirring paddle of the reactor in step 3 is an anchor-type stirring paddle, and the vacuum degree inside the reactor is maintained at -0.05 to -0.03 MPa during the stirring process.

[0040] Preferably, the working chamber temperature of the high-shear homogenizer in step 5 is controlled at 40-45℃.

[0041] Preferably, in step 7, the solder paste is stirred every 8 hours during the aging process, with a stirring speed of 100-150 rpm and a stirring time of 5 minutes.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] This invention significantly improves the dispensing performance of syringe solder paste through the synergistic effect of solder powder and flux, ensuring stable solder dispensing during continuous dispensing and a significant reduction in hole blockage. The addition of antioxidants and metal chelating agents effectively inhibits solder paste oxidation and delamination, resulting in low viscosity change after 30 days of storage and significantly improved storage stability. Ensuring a uniform and stable solder paste system with a reasonable particle size distribution further guarantees dispensing performance and soldering results. Attached Figure Description

[0044] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0046] Please see Figure 1 This invention provides a technical solution: a highly stable dot-applied syringe solder paste, composed of the following components by weight percentage:

[0047] The composition includes: solder powder 82.0-88.0%, hydrogenated rosin 3.5-5.0%, modified phenolic resin 1.2-2.0%, adipic acid 0.8-1.5%, diethylamine hydrobromide 0.5-1.0%, propylene glycol methyl ether acetate 2.0-3.5%, hydrogenated castor oil 0.6-1.2%, polyamide wax 0.3-0.8%, 2,6-di-tert-butyl-p-cresol 0.1-0.3%, polyoxyethylene sorbitan monooleate 0.2-0.5%, fumed silica 0.3-0.7%, disodium ethylenediaminetetraacetate 0.05-0.15%, and benzotriazole 0.1-0.3%.

[0048] The functions of each component in the raw material are as follows:

[0049] Solder powder: provides the metal matrix required for welding, ensuring the mechanical strength and conductivity of the solder joint. It is composed of tin, silver, copper and bismuth in a specific ratio and has a low melting point and high fluidity.

[0050] Hydrogenated rosin: As the main component of flux, it has good wettability, can remove the oxide layer on the metal surface, and promote solder spreading.

[0051] Modified phenolic resin: enhances the bonding strength of solder paste, improves the impact resistance of solder joints, and improves the film-forming properties of solder paste.

[0052] Adipic acid: As an organic acid activator, it helps remove metal oxide films and improves welding activity.

[0053] Diethylamine hydrobromide: An organic amine hydrohalide activator that enhances soldering performance, especially for copper substrates.

[0054] Propylene glycol methyl ether acetate: an environmentally friendly solvent that adjusts the viscosity of solder paste, ensuring smooth application during dotting, and promoting compatibility among components.

[0055] Hydrogenated castor oil: a thixotropic agent that imparts good thixotropic properties to solder paste, allowing it to flow well when applied and maintain its shape when left to stand, thus reducing collapse.

[0056] Polyamide wax: works synergistically with thixotropic agents to further optimize the rheological properties of solder paste and improve the stability of continuous dotting.

[0057] 2,6-Di-tert-butyl-p-cresol: An antioxidant that inhibits oxidation and deterioration of solder paste during storage and use, extending its shelf life.

[0058] Polyoxyethylene sorbitan monooleate: a nonionic surfactant that reduces interfacial tension, improves the compatibility of solder powder and flux, and reduces agglomeration.

[0059] Fumed silica: a thickener that adjusts the viscosity of solder paste, prevents solder powder from settling, and improves system stability.

[0060] Disodium EDTA: A metal chelating agent that forms stable chelates with metal ions, preventing catalytic oxidation reactions by metal ions and enhancing storage stability.

[0061] Benzotriazole: a corrosion inhibitor that protects metal surfaces, prevents subsequent corrosion of weld joints, and improves the long-term reliability of welded joints.

[0062] The solder powder is composed of tin, silver, copper, and bismuth in a mass ratio of 96.5:3.0:0.3:0.2, with a particle size of 20-38 micrometers; the hydrogenated rosin has an acid value of 160-180 mgKOH / g and a softening point of 75-85℃; the modified phenolic resin has a molecular weight of 3000-5000 and a softening point of 90-100℃.

[0063] A method for preparing a highly stable dot-applied syringe solder paste includes the following steps:

[0064] Step 1: Solder powder preparation: Tin, silver, copper, and bismuth are added to a vacuum melting furnace at a mass ratio of 96.5:3.0:0.3:0.2. Under inert gas protection, the mixture is melted and mixed at 280-320℃ for 30-40 minutes to form an alloy melt. The melt is then atomized into powder using a gas atomization method at a pressure of 3-5 MPa. After cooling, solder powder with a particle size of 20-38 micrometers is screened out for later use. The inert gas is nitrogen or argon, and the cooling medium for the gas atomization method is compressed air.

[0065] Step 2, Raw material pretreatment: Dry hydrogenated rosin and modified phenolic resin in a vacuum drying oven at 60-70℃ for 2-3 hours to remove moisture; grind solid raw materials such as adipic acid and diethylamine hydrobromide to an 80-100 mesh sieve to ensure uniform particle size;

[0066] Step 3, Flux Preparation: Add propylene glycol methyl ether acetate to the reactor, heat to 40-50℃, stir at 200-300 rpm, add hydrogenated rosin and modified phenolic resin sequentially until dissolved; add adipic acid and diethylamine hydrobromide, stir for 15-20 minutes; add hydrogenated castor oil and polyamide wax, heat to 60-65℃, stir for 30-40 minutes; add 2,6-di-tert-butyl-p-cresol, polyoxyethylene sorbitan monooleate, fumed silica, disodium ethylenediaminetetraacetate, and benzotriazole, stir for 25-35 minutes to obtain the flux; the reactor's agitator is an anchor-type agitator, and the vacuum degree inside the reactor is maintained at -0.05 to -0.03 MPa during stirring;

[0067] Step 4, Mixing: Add the solder powder prepared in Step 1 and the flux prepared in Step 3 to a double planetary mixer at a mass ratio of 85:15. Under nitrogen protection, stir at 500-600 rpm for 10-15 minutes to allow the powder to be initially wetted.

[0068] Step 5, Homogenization: Transfer the mixed materials to a high-shear homogenizer, set the speed to 3000-4000 rpm, and homogenize for 20-30 minutes to evenly disperse the solder powder in the flux and form preliminary solder paste; control the working chamber temperature of the high-shear homogenizer at 40-45℃.

[0069] Step 6, Degassing treatment: Place the preliminary solder paste into a vacuum degassing machine and degas for 15-20 minutes under vacuum conditions of -0.09 to -0.08 MPa and temperature of 30-35℃ to remove internal air bubbles;

[0070] Step 7, Aging treatment: Aging the defoamed material in a constant temperature chamber at 25-30℃ for 24-48 hours; During the aging treatment, the solder paste is stirred once every 8 hours at a stirring speed of 100-150 rpm for 5 minutes.

[0071] Step 8, Sieving and Filtration: Use a 100-120 mesh sieve to filter the aged solder paste to remove any large particles that may be present.

[0072] Step 9, Filling: In a cleanroom environment with a cleanliness level of 1000, quantitatively fill the solder paste into the syringe at a filling pressure of 0.2-0.3 MPa to avoid introducing air bubbles;

[0073] Step 10, Packaging: Seal the filled syringes with aluminum-plastic composite film and store them at 4-10℃.

[0074] Example 1:

[0075] Formula composition (by weight):

[0076] The composition includes 85.0% solder powder, 4.2% hydrogenated rosin, 1.6% modified phenolic resin, 1.1% adipic acid, 0.7% diethylamine hydrobromide, 2.8% propylene glycol methyl ether acetate, 0.9% hydrogenated castor oil, 0.5% polyamide wax, 0.2% 2,6-di-tert-butyl-p-cresol, 0.3% polyoxyethylene sorbitan monooleate, 0.5% fumed silica, 0.1% disodium ethylenediaminetetraacetate, and 0.2% benzotriazole.

[0077] Preparation method:

[0078] Step 1: In the preparation of solder powder, the melting temperature is 300℃, the atomization pressure is 4MPa, and the powder with a particle size of 25-35 micrometers is screened.

[0079] Step 3: When preparing the flux, heat the propylene glycol methyl ether acetate to 45°C, stir at 250 rpm, add all the components, and operate according to the above time and temperature parameters.

[0080] Step 4: Mix at 550 rpm using a dual planetary mixer for 12 minutes.

[0081] Step 5: Homogenize for 25 minutes at 3500 rpm using a high-shear homogenizer.

[0082] Step 6: Vacuum degassing, vacuum degree -0.085MPa, temperature 32℃, time 18 minutes.

[0083] Step 7: Aging temperature 28℃, time 36 hours.

[0084] Example 2:

[0085] Formula composition (by weight):

[0086] The composition includes: solder powder 82.0%, hydrogenated rosin 5.0%, modified phenolic resin 2.0%, adipic acid 1.5%, diethylamine hydrobromide 1.0%, propylene glycol methyl ether acetate 3.5%, hydrogenated castor oil 1.2%, polyamide wax 0.8%, 2,6-di-tert-butyl-p-cresol 0.3%, polyoxyethylene sorbitan monooleate 0.5%, fumed silica 0.7%, disodium ethylenediaminetetraacetate 0.15%, and benzotriazole 0.3%.

[0087] Preparation method:

[0088] Step 1: Melting temperature 280℃, atomization pressure 3MPa, and screening of powder with a particle size of 20-30 micrometers.

[0089] Step 3: Heat propylene glycol methyl ether acetate to 40°C and stir at 200 rpm.

[0090] Step 4: Mix at 500 rpm for 15 minutes.

[0091] Step 5: Homogenize at 3000 rpm for 30 minutes.

[0092] Step 6: Degassing vacuum degree -0.09MPa, temperature 30℃, time 20 minutes.

[0093] Step 7: Aging temperature 25℃, time 48 hours.

[0094] Example 3:

[0095] Formula composition (by weight):

[0096] The composition includes: 88.0% solder powder, 3.5% hydrogenated rosin, 1.2% modified phenolic resin, 0.8% adipic acid, 0.5% diethylamine hydrobromide, 2.0% propylene glycol methyl ether acetate, 0.6% hydrogenated castor oil, 0.3% polyamide wax, 0.1% 2,6-di-tert-butyl-p-cresol, 0.2% polyoxyethylene sorbitan monooleate, 0.3% fumed silica, 0.05% disodium ethylenediaminetetraacetate, and 0.1% benzotriazole.

[0097] Preparation method:

[0098] Step 1: Melting temperature 320℃, atomization pressure 5MPa, and screening of powder with a particle size of 30-38 micrometers.

[0099] Step 3: Heat propylene glycol methyl ether acetate to 50°C and stir at 300 rpm.

[0100] Step 4: Mix at 600 rpm for 10 minutes.

[0101] Step 5: Homogenize at 4000 rpm for 20 minutes.

[0102] Step 6: Degassing vacuum degree -0.08MPa, temperature 35℃, time 15 minutes.

[0103] Step 7: Aging temperature 30℃, time 24 hours.

[0104] The following table compares Embodiments 1-3 of the present invention with the prior art:

[0105]

[0106]

[0107] This invention significantly improves the dispensing performance of syringe solder paste through the synergistic effect of solder powder and flux, ensuring stable solder dispensing during continuous dispensing and a significant reduction in hole blockage. The addition of antioxidants and metal chelating agents effectively inhibits solder paste oxidation and delamination, resulting in low viscosity change after 30 days of storage and significantly improved storage stability. Ensuring a uniform and stable solder paste system with a reasonable particle size distribution further guarantees dispensing performance and soldering results.

[0108] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A highly stable dot-applied syringe solder paste, characterized in that, It consists of the following components by weight percentage: The composition includes: solder powder 82.0-88.0%, hydrogenated rosin 3.5-5.0%, modified phenolic resin 1.2-2.0%, adipic acid 0.8-1.5%, diethylamine hydrobromide 0.5-1.0%, propylene glycol methyl ether acetate 2.0-3.5%, hydrogenated castor oil 0.6-1.2%, polyamide wax 0.3-0.8%, 2,6-di-tert-butyl-p-cresol 0.1-0.3%, polyoxyethylene sorbitan monooleate 0.2-0.5%, fumed silica 0.3-0.7%, disodium ethylenediaminetetraacetate 0.05-0.15%, and benzotriazole 0.1-0.3%.

2. The high-stability dot-applied syringe solder paste according to claim 1, characterized in that, It consists of the following components by weight percentage: The composition includes 85.0% solder powder, 4.2% hydrogenated rosin, 1.6% modified phenolic resin, 1.1% adipic acid, 0.7% diethylamine hydrobromide, 2.8% propylene glycol methyl ether acetate, 0.9% hydrogenated castor oil, 0.5% polyamide wax, 0.2% 2,6-di-tert-butyl-p-cresol, 0.3% polyoxyethylene sorbitan monooleate, 0.5% fumed silica, 0.1% disodium ethylenediaminetetraacetate, and 0.2% benzotriazole.

3. The high-stability dot-applied syringe solder paste according to claim 1, characterized in that, It consists of the following components by weight percentage: The composition includes: solder powder 82.0%, hydrogenated rosin 5.0%, modified phenolic resin 2.0%, adipic acid 1.5%, diethylamine hydrobromide 1.0%, propylene glycol methyl ether acetate 3.5%, hydrogenated castor oil 1.2%, polyamide wax 0.8%, 2,6-di-tert-butyl-p-cresol 0.3%, polyoxyethylene sorbitan monooleate 0.5%, fumed silica 0.7%, disodium ethylenediaminetetraacetate 0.15%, and benzotriazole 0.3%.

4. The high-stability dot-applied syringe solder paste according to claim 1, characterized in that, It consists of the following components by weight percentage: The composition includes: 88.0% solder powder, 3.5% hydrogenated rosin, 1.2% modified phenolic resin, 0.8% adipic acid, 0.5% diethylamine hydrobromide, 2.0% propylene glycol methyl ether acetate, 0.6% hydrogenated castor oil, 0.3% polyamide wax, 0.1% 2,6-di-tert-butyl-p-cresol, 0.2% polyoxyethylene sorbitan monooleate, 0.3% fumed silica, 0.05% disodium ethylenediaminetetraacetate, and 0.1% benzotriazole.

5. A highly stable dot-applied syringe solder paste according to any one of claims 1-4, characterized in that, The solder powder is composed of tin, silver, copper, and bismuth in a mass ratio of 96.5:3.0:0.3:0.2, with a particle size of 20-38 micrometers; the hydrogenated rosin has an acid value of 160-180 mgKOH / g and a softening point of 75-85℃; the modified phenolic resin has a molecular weight of 3000-5000 and a softening point of 90-100℃.

6. A method for preparing a highly stable dot-applied syringe solder paste according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Solder powder preparation: Tin, silver, copper, and bismuth are added to a vacuum melting furnace at a mass ratio of 96.5:3.0:0.3:0.

2. Under inert gas protection, the mixture is melted and mixed at 280-320℃ for 30-40 minutes to form an alloy melt. The melt is then atomized into powder using a gas atomization method at a pressure of 3-5 MPa. After cooling, solder powder with a particle size of 20-38 micrometers is screened out for later use. Step 2, Raw material pretreatment: Dry hydrogenated rosin and modified phenolic resin separately in a vacuum drying oven at 60-70℃ for 2-3 hours; grind adipic acid and diethylamine hydrobromide to an 80-100 mesh sieve; Step 3, Flux Preparation: Add propylene glycol methyl ether acetate to the reactor, heat to 40-50℃, stir at 200-300 rpm, add hydrogenated rosin and modified phenolic resin sequentially until dissolved; add adipic acid and diethylamine hydrobromide, stir for 15-20 minutes; add hydrogenated castor oil and polyamide wax, heat to 60-65℃, stir for 30-40 minutes; add 2,6-di-tert-butyl-p-cresol, polyoxyethylene sorbitan monooleate, fumed silica, disodium ethylenediaminetetraacetate, and benzotriazole, stir for 25-35 minutes to obtain the flux; Step 4, Mixing: Add the solder powder from Step 1 and the flux from Step 3 to a double planetary mixer at a mass ratio of 85:15, and stir for 10-15 minutes at 500-600 rpm under nitrogen protection. Step 5, Homogenization: Transfer the mixture to a high-shear homogenizer and homogenize at 3000-4000 rpm for 20-30 minutes; Step 6, Degassing treatment: Degas the homogenized material for 15-20 minutes under vacuum conditions of -0.09 to -0.08 MPa and 30-35℃. Step 7, Aging treatment: Aging the degassed material in a constant temperature chamber at 25-30℃ for 24-48 hours; Step 8, Sieving and Filtration: Use a 100-120 mesh sieve for filtration; Step 9, Filling: In a Class 1000 cleanroom environment, fill the syringe with a pressure of 0.2-0.3 MPa; Step 10, Packaging: Sealed packaging with aluminum-plastic composite film, stored at 4-10℃.

7. The method for preparing a highly stable dot-applied syringe solder paste according to claim 6, characterized in that, The inert gas in step 1 is nitrogen or argon, and the cooling medium for the gas atomization method is compressed air.

8. The method for preparing a highly stable dot-applied syringe solder paste according to claim 6, characterized in that, The stirring paddle in the reactor in step 3 is an anchor-type stirring paddle, and the vacuum degree inside the reactor is maintained at -0.05 to -0.03 MPa during the stirring process.

9. The method for preparing a highly stable dot-applied syringe solder paste according to claim 6, characterized in that, In step 5, the working chamber temperature of the high-shear homogenizer is controlled at 40-45℃.

10. The method for preparing a highly stable dot-applied syringe solder paste according to claim 6, characterized in that, In step 7, during the aging process, the solder paste is stirred once every 8 hours at a stirring speed of 100-150 rpm for 5 minutes.

Images