High Stability Welding Paste Technology
A revolutionary advancement in electronic soldering technology, our high-performance welding paste offers exceptional stability, improved dispersion, and superior soldering results.
Technical Field
This invention relates to the field of electronic soldering technology, specifically to a high-stability welding paste and its preparation method. As electronic information products develop toward ultra-large-scale integration and miniaturization, welding paste has become the most important process material in surface mount technology (SMT).
The demand for high-performance welding paste continues to grow as electronic devices become more complex and miniaturized. Our innovative welding paste formulation addresses critical challenges in the industry, providing enhanced stability and performance characteristics that exceed traditional alternatives.
Background Technology
Traditional welding paste generally uses SAC series alloys (tin-silver-copper series alloys) as welding materials. The soldering temperature usually needs to be higher than 240°C, which can easily cause component deformation during the welding process of highly integrated microelectronic devices. Therefore, welding paste using tin-bismuth series alloys as low-temperature solder is currently widely adopted.
However, because this type of welding paste contains a large amount of bismuth metal, the toughness of the solder joints is relatively low. Carbon nanotubes, with their excellent mechanical, electrical, and thermal properties, are developing into an excellent reinforcement phase for traditional welding paste. Unfortunately, due to their nano-size effect and surface inertness, they are not easily dispersed in welding paste, have low solubility in solvents, and exhibit poor compatibility with other components, especially tin-bismuth series alloys.
Current research mostly involves surface metallization of carbon nanotubes to enhance compatibility with tin alloys, but this method has complex processes, high costs, and unstable product quality. While attempts have been made to mix carbon nanotubes in their pure form with tin alloys to produce solder, followed by adding flux paste containing specific components, these approaches still fail to solve the problem of storage stability in welding paste.
Traditional Limitations
- Poor dispersion of carbon nanotubes in welding paste
- Low compatibility with tin-bismuth alloys
- Inadequate storage stability of welding paste
- Poor printability and solder joint quality
Our Innovation
- Enhanced dispersion through modified carbon nanotubes
- Superior compatibility in welding paste formulation
- Exceptional storage stability of welding paste
- Improved printability and high-quality solder joints
Invention Content
To solve the above technical problems, the first aspect of the present invention provides a high-stability welding paste. According to weight percentage, the raw materials of the high-stability welding paste include 84-87% solder and 13-16% flux paste. The solder includes tin-bismuth series alloys and carbon nanotubes. Based on the flux paste as a reference, according to parts by weight, the flux paste includes 20-50 parts of rosin, 20-40 parts of solvent, 5-15 parts of active agent, 5-10 parts of thickener, and 1-5 parts of additives.
Key Components
Solder Composition (84-87%)
- Tin-bismuth series alloys: Preferred is Sn42Bi58, which provides excellent low-temperature soldering properties essential for modern electronic components
- Carbon nanotubes: Account for 0.01-1wt% of the solder, with 0.57wt% being optimal. These nanotubes are specially modified to enhance their performance in the welding paste
Flux Paste Composition (13-16%)
- Rosin: 20-50 parts, providing essential tackiness and protection
- Solvent: 20-40 parts, ensuring proper viscosity and application properties
- Active agent: 5-15 parts, promoting wetting and bonding
- Thickener: 5-10 parts, controlling the consistency of the welding paste
- Additives: 1-5 parts, enhancing specific performance characteristics
Modified Carbon Nanotubes
A critical innovation in our welding paste is the use of modified carbon nanotubes, which significantly improve dispersion and compatibility within the welding paste matrix.
The preparation method includes the following steps: Add carbon nanotubes into ethanol solvent, add modifier under stirring, react for 12-24 hours at 70-80°C under nitrogen atmosphere, filter, wash, and dry to obtain the modified carbon nanotubes.
Optimal Modification Parameters
- Modifier to carbon nanotube mass ratio: (0.15～0.2)：1, preferably 0.18：1
- Reaction temperature: 70～80℃
- Reaction time: 12～24h
- Reaction atmosphere: Nitrogen
The modifier is a C12～C18 alkyl silane coupling agent. Examples include dodecyltrimethoxysilane (CAS No: 3069-21-4), dodecyltriethoxysilane (CAS No: 18536-91-9), cetyltrimethoxysilane (CAS No: 16415-12-6), cetyltriethoxysilane (CAS No: 16415-13-7), octadecyltrimethoxysilane (CAS No: 3069-42-9), and octadecyltriethoxysilane (CAS No: 7399-00-0).
Rosin Component
The rosin in our welding paste is selected from at least one of acrylic rosin, disproportionated rosin, hydrogenated rosin, and polymerized rosin. From the perspective of improving the thermal stability, oxidation resistance, and wettability of the welding paste, a preferred embodiment uses hydrogenated rosin and polymerized rosin in a weight ratio of (3～5)：1, with 4：1 being most optimal.
Each type of rosin contributes unique properties to the welding paste:
Acrylic Rosin
Produced by reaction of rosin and acrylic acid, providing good adhesion properties to the welding paste.
Disproportionated Rosin
Offers improved thermal stability, beneficial for high-temperature performance of the welding paste.
Hydrogenated Rosin
Provides excellent oxidation resistance, extending the shelf life of the welding paste.
Polymerized Rosin
Offers enhanced viscosity control, improving the application properties of the welding paste.
Solvent System
The solvent in our welding paste is selected from at least one of tetrahydrofurfuryl alcohol (CAS No: 97-99-4), terpineol (CAS No: 10482-56-1), diethylene glycol hexyl ether (CAS No: 112-59-4), tetraethylene glycol methyl ether (CAS No: 23783-42-8), diethylene glycol butyl ether (CAS No: 203-961-6), ethylene glycol phenyl ether (CAS No: 122-99-6), and triethylene glycol butyl ether (CAS No: 143-22-6).
In a preferred embodiment, the solvent is tetrahydrofurfuryl alcohol and terpineol in a mass ratio of 8：(2～5), with 8：3 being most preferred. This specific solvent combination provides exceptional stability to the welding paste, preventing drying and maintaining optimal viscosity over time.
The low volatility and unique molecular structures of these solvents—with their cyclic and hydroxyl groups—create intermolecular forces with the modified carbon nanotubes in the welding paste. This interaction prevents solvent loss during storage and maintains effective activity during the soldering process, improving the wettability of the welding paste on substrate surfaces.
Active Agents
The active agent in our welding paste is selected from at least one of succinic acid, adipic acid, azelaic acid, and suberic acid. In a preferred embodiment, the active agent also includes ammonium hydrogen fluoride (CAS No: 1341-49-7).
Most preferably, the active agent is adipic acid and ammonium hydrogen fluoride in a weight ratio of 1：0.03. This specific combination has been found to significantly reduce post-soldering residues in the welding paste.
The fluoride ions from ammonium hydrogen fluoride provide crystallization refinement, while also improving the rheological properties of the welding paste during printing. However, due to its corrosive nature, careful control of ammonium hydrogen fluoride content is essential to prevent metal alloy corrosion in the welding paste, which could lead to sanding phenomena during storage.
Thickeners and Additives
The thickener in our welding paste is selected from at least one of polyamide wax, hydrogenated castor oil, ethylene bis-stearamide, ethylene bis-lauramide, and ethylene bis-12-hydroxystearamide.
In a preferred embodiment, the thickener is hydrogenated castor oil and ethylene bis-stearamide in a weight ratio of 3：1. This combination provides optimal viscosity control for the welding paste, ensuring excellent printability and shape retention.
The additives in our welding paste include corrosion inhibitors and anti-aging agents. Benzotriazole (CAS No: 95-14-7) is used as a corrosion inhibitor, while antioxidant 1010 (tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester, CAS No: 6683-19-8) serves as an anti-aging agent. These additives work together to extend the shelf life of the welding paste and improve its overall performance.
Preparation Method
The second aspect of the present invention provides a method for preparing the above high-stability welding paste, which includes the following steps:
Initial Mixture Preparation
Add rosin, solvent, active agent, and additives into a container. Under stirring at 90～110℃, continue mixing until the solution becomes transparent. This step ensures complete dissolution and homogeneous dispersion of the organic components that form the base of our welding paste.
Temperature Adjustment
Increase the temperature of the mixture to 130～150℃. This temperature adjustment prepares the mixture for optimal incorporation of the metallic components while maintaining the integrity of the welding paste matrix.
Final Incorporation
Add the solder (including tin-bismuth alloy and modified carbon nanotubes) and thickener into the container. Stir for 5～7 minutes to achieve complete and uniform dispersion of all components. This final step ensures the welding paste has the ideal consistency and component distribution.
Cooling and Packaging
Allow the mixture to cool to ambient temperature under controlled conditions. The resulting welding paste is then ready for packaging in appropriate containers that protect it from moisture and contamination, ensuring maximum shelf life.
Beneficial Effects
The high-stability welding paste provided by the present invention offers numerous advantages over conventional products:
Improved Dispersion & Compatibility
Through modification treatment of carbon nanotubes with C12～C18 alkyl silane coupling agents, the dispersion and compatibility of carbon nanotubes in the welding paste are significantly improved. This prevents agglomeration and caking phenomena that plague traditional welding paste products.
Enhanced Storage Stability
The unique formulation significantly enhances the storage stability of the welding paste. Our welding paste maintains its consistency and performance characteristics over extended periods, reducing waste and ensuring reliability in production.
Superior Printability
The carefully balanced composition improves the printability of the welding paste, ensuring precise application in even the most demanding electronic manufacturing processes. This results in consistent, high-quality solder deposits.
Excellent Solder Joint Quality
Welds produced with our welding paste feature bright,饱满 solder joints with excellent spreadability. The reduction in post-soldering residues eliminates the need for additional cleaning processes, saving time and resources.
Claims Summary
- A high-stability welding paste, characterized in that, according to weight percentage, the raw materials of the high-stability welding paste include 84-87% solder and 13-16% flux paste; the solder includes tin-bismuth series alloys and carbon nanotubes; based on the flux paste as a reference, according to parts by weight, the flux paste includes 20-50 parts of rosin, 20-40 parts of solvent, 5-15 parts of active agent, 5-10 parts of thickener, and 1-5 parts of additives.
- The high-stability welding paste according to claim 1, characterized in that the carbon nanotubes account for 0.01-1wt% of the solder.
- The high-stability welding paste according to claim 2, characterized in that the carbon nanotubes are modified carbon nanotubes, and the preparation method includes the following steps: adding carbon nanotubes into ethanol solvent, adding modifier under stirring, reacting for 12-24 hours at 70-80°C under nitrogen atmosphere, filtering, washing, and drying to obtain the modified carbon nanotubes.
- The high-stability welding paste according to claim 3, characterized in that the mass ratio of the modifier to the carbon nanotubes is (0.15-0.2):1.
- The high-stability welding paste according to claim 3, characterized in that the modifier is a C12～C18 alkyl silane coupling agent.
- The high-stability welding paste according to claim 1, characterized in that the solvent is selected from at least one of tetrahydrofurfuryl alcohol, terpineol, diethylene glycol hexyl ether, tetraethylene glycol methyl ether, diethylene glycol butyl ether, ethylene glycol phenyl ether, and triethylene glycol butyl ether.
- The high-stability welding paste according to claim 6, characterized in that the solvent is tetrahydrofurfuryl alcohol and terpineol in a mass ratio of 8:(2-5).
- The high-stability welding paste according to claim 1, characterized in that the active agent is selected from at least one of succinic acid, adipic acid, azelaic acid, and suberic acid.
- The high-stability welding paste according to claim 8, characterized in that the active agent further includes ammonium hydrogen fluoride.
- A method for preparing the high-stability welding paste according to any one of claims 1-9, characterized in that it includes the following steps: adding rosin, solvent, active agent, and additives into a container, and stirring at 90-110°C until the solution becomes transparent; heating to 130-150°C, adding solder and thickener into the container, and stirring for 5-7 minutes to obtain the high-stability welding paste.
Revolutionary Welding Paste Technology
Our high-stability welding paste represents a significant advancement in electronic soldering technology. By addressing the critical challenges of dispersion, compatibility, and storage stability, this innovative welding paste delivers superior performance in modern electronics manufacturing.
With its exceptional printability, high-quality solder joints, and reduced post-soldering residues, our welding paste offers substantial benefits for electronic manufacturing processes, from improved product quality to increased production efficiency.
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