High-temperature solder paste for chip subpackaging

Abstract

The invention relates to the technical field of electronic packaging materials, and discloses a high-temperature solder paste for chip subpackaging, which comprises the following components in percentage by weight: 85-90% of high-temperature lead-free electronic grade tin alloy powder which is specifically Sn 96.5, Ag 3.0 and Cu 0.5 series alloy and has the particle size range of 10-30 mu m; 10%-15% of a high-temperature-resistant soldering flux; and the balance of an organic solvent. The high-temperature solder paste for chip subpackaging has remarkable effects in the aspects of improving the welding quality, enhancing the high-temperature resistance, optimizing the thixotropy and fluidity, enhancing the surface activation and cleaning effect, improving the process stability and consistency, being green and environmentally friendly and the like; and the method has important practical significance for promoting the development and application of the precision chip split charging and welding technology.

Description

Technical Field

[0001] The invention relates to the technical field of electronic packaging materials, in particular to a high-temperature solder paste for chip packaging. Background Art

[0002] In the modern electronics industry, with the rapid development of chip technology, the requirements for soldering materials are getting higher and higher. Traditional solder materials contain lead, which is harmful to the environment and human health, so lead-free solder paste has gradually become the mainstream choice in the market. Especially in high-temperature applications, solder paste not only needs to have good conductivity and mechanical strength, but also needs to maintain stable performance in high temperature environments.

[0003] Existing lead-free solder pastes often face some challenges in high-temperature applications. For example, problems such as uneven solder joints, insufficient solder strength, and difficulty in cleaning post-solder residues are likely to occur during the soldering process. These problems not only affect the soldering quality, but may also cause electronic products to malfunction during use. Therefore, the market is in urgent need of a lead-free solder paste that can perform well under high-temperature conditions. Summary of the invention

[0004] The present invention proposes a high-temperature solder paste for chip subpackaging, aiming to solve the above problems. The activation and cleaning effects in the welding process are improved by combining a specific ratio of high-temperature lead-free tin alloy powder and an optimized high-temperature resistant flux; at the same time, the uniformity and stability of the solder paste are ensured through a strict preparation process, thereby greatly improving the welding quality and reliability; the solder paste prepared by the present invention can better meet the needs of the modern electronics industry for high-performance welding materials.

[0005] To achieve the above object, the present invention provides the following technical solution: a high-temperature solder paste for chip packaging, characterized in that it comprises the following components in percentage by weight: High temperature lead-free electronic grade tin alloy powder: 85% to 90%, the tin alloy powder is specifically Sn96.5Ag3.0Cu0.5 alloy, with a particle size range of 10 to 30μm; High temperature resistant soldering flux: 10% to 15%, the high temperature resistant soldering flux is composed of the following raw materials in percentage by weight: Diethylene glycol monobutyl ether: 15% to 20%; Hydrogenated castor oil: 5%-8%; Polymerized rosin CLEARON 105#: 20%~25%; Special grade hydrogenated rosin AX-E: 15% to 20%; Fluorocarbon surfactant FSN100: 0.5%~1.0%; Triethanolamine: 0.5%~1.0%; High temperature resistant thixotropic agent: 5%~10%; High temperature resistant active agent: 2%~5%; The balance is organic solvent.

[0006] Preferably, the weight ratio of ethylene bisstearamide to high-performance amide wax micropowder in the high temperature resistant thixotropic agent is 1:1 to 3:1, so as to adjust the thixotropic properties and fluidity of the solder paste to make it more suitable for the sub-packaging and welding of precision chips.

[0007] Preferably, the high temperature resistant activator comprises at least one fluorosurfactant, and the weight ratio of the fluorosurfactant to decyltetradecanoic acid is 1:3 to 1:5, so as to enhance the activation and cleaning effect of the solder paste on the metal surface during the welding process and improve the welding strength.

[0008] Preferably, the organic solvent is a butyl carbitol-terpineol mixture.

[0009] Preferably, the preparation method of the high-temperature solder paste for chip packaging comprises the following steps: (a) adding diethylene glycol monobutyl ether, hydrogenated castor oil, polymerized rosin CLEARON 105#, special hydrogenated rosin AX-E, high-temperature resistant thixotropic agent, high-temperature resistant activator and part of organic solvent into a temperature-controlled emulsifier, heating to 120-130° C., and stirring at a speed of 300 r / min for 10-15 minutes to obtain a primary mixed solution; (b) adding fluorocarbon surfactant FSN100 and triethanolamine into the primary mixed solution, continuing to stir and evacuate to a vacuum value of 0.05 MPa until the temperature returns to room temperature to obtain a soldering flux; (c) After the flux prepared in step (b) is allowed to stand at a temperature of 5 to 10° C. for 24 hours, it is added to a dual planetary solder paste mixer, and high-temperature lead-free electronic grade tin alloy powder is slowly added at a temperature of 20 to 25° C. The stirring speed is controlled to be 500 r / min, and the stirring time is 20 to 30 minutes to obtain a uniform high-temperature solder paste for chip packaging.

[0010] Preferably, in step (b), during the process of stirring and evacuating to a vacuum value of 0.05 MPa, an intermediate stirring is also performed when the temperature drops to 90°C, and the stirring time is 5-10 minutes, and then the temperature is further cooled to room temperature to ensure that the fluorocarbon surfactant FSN100 and triethanolamine are completely integrated into the solution, thereby further improving the soldering effect and fluidity of the flux.

[0011] Preferably, in step (c), the high temperature lead-free electronic grade tin alloy powder needs to be pre-dried before being added to the dual planetary solder paste mixer, that is, dried at 80-90°C for 2-3 hours to remove surface moisture and impurities and prevent bubbles from being generated during the mixing process, thereby improving the purity of the solder paste and the welding quality.

[0012] Preferably, in step (c), the stirring process further includes pausing for 1 minute after stirring for 15 minutes, and then continuing to stir at the same speed for a preset time. This operation allows the tin alloy powder and the flux solution to more fully penetrate and fuse with each other, forming a more uniform and stable solder paste system.

[0013] The invention provides a high-temperature solder paste for chip packaging, which has the following beneficial effects: 1. Improve welding quality: Use Sn96.5Ag3.0Cu0.5 alloy as high-temperature lead-free electronic grade tin alloy powder. This alloy has excellent physical and mechanical properties, can maintain stable welding effect at high temperature, and reduces the emission of harmful substances, meeting environmental protection requirements.

[0014] 2. Enhanced high temperature resistance: The formula design of high temperature resistant flux, especially the use of fluorocarbon surfactant FSN100, triethanolamine and a specific proportion of high temperature resistant thixotropic agent and high temperature resistant activator, significantly enhances the stability and activity of solder paste in high temperature environment, effectively prevents oxidation and corrosion during welding, and improves the heat resistance and durability of welding joints.

[0015] 3. Optimizing thixotropy and fluidity: By precisely adjusting the weight ratio of ethylene bisstearamide and high-performance amide wax micropowder in the high-temperature resistant thixotropic agent, the present invention successfully adjusts the thixotropic properties and fluidity of the solder paste, so that it can maintain a stable shape during storage and transportation, and can flow quickly and cover the chip surface during welding. It is very suitable for the sub-packaging and welding of precision chips, and improves production efficiency.

[0016] 4. Strengthening surface activation and cleaning effects: The specific ratio combination of fluorinated surfactant and decyl tetradecanoic acid in the high temperature resistant activator effectively enhances the activation and cleaning effect of solder paste on the metal surface during the welding process, removes oxides and dirt on the metal surface, and promotes the close bonding between the solder and the substrate, thereby significantly improving the welding strength and reliability.

[0017] 5. Improve process stability and consistency: The standardized preparation process, including strict temperature control, vacuum treatment, pre-drying treatment, and pauses during stirring, ensures the uniformity and stability of the solder paste, reduces fluctuations and errors in the production process, and improves the process consistency and quality stability of the product.

[0018] In summary, the high-temperature solder paste for chip packaging of the present invention shows remarkable effects in improving welding quality, enhancing high temperature resistance, optimizing thixotropy and fluidity, strengthening surface activation and cleaning effects, improving process stability and consistency, and green environmental protection, and has important practical significance for promoting the development and application of precision chip packaging welding technology. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1: Preparation process: Weigh the following raw materials according to weight percentage: High temperature lead-free electronic grade tin alloy powder (Sn96.5Ag3.0Cu0.5, particle size 10-30μm): 87.5%; Diethylene glycol monobutyl ether: 17.5%; Hydrogenated castor oil: 6.5%; Polymerized rosin CLEARON 105#: 22.5%; Extra-grade hydrogenated rosin AX-E: 17.5%; Fluorocarbon surfactant FSN100: 0.75%; Triethanolamine: 0.75%; High temperature resistant thixotropic agent (ethylene bisstearamide: high performance amide wax micropowder = 2:1): 7.5%; High temperature resistant active agent (fluorinated surfactant: decyl tetradecanoic acid = 1:4): 3.5%; Organic solvent (butyl carbitol-terpineol mixture): make up to 100%.

[0021] All flux components except fluorocarbon surfactant FSN100 and triethanolamine and part of organic solvent are mixed in proportion, heated to 125°C in a temperature-controlled emulsifier, and stirred at 300r / min for 12 minutes to obtain a mixed solution; FSN100 and triethanolamine are added to the above solution, and the stirring is continued and the solution is evacuated to 0.05MPa. When the temperature drops to 90°C, an intermediate stirring is performed for 5 minutes, and then the temperature is cooled to room temperature to obtain the flux; after the flux is allowed to stand at 8°C for 24 hours, it is added to a double planetary solder paste mixer, and pre-dried (dried at 85°C for 2.5 hours) high-temperature lead-free electronic grade tin alloy powder is slowly added at 22°C, and stirred at 500r / min for 25 minutes, and a 1 minute pause is made at 15 minutes to obtain a uniform solder paste.

[0022] Performance parameters: Viscosity (25°C): 200±20Pa·s; Initial activation temperature: 180°C; Melting temperature range: 215-225℃; Welding strength: ≥25MPa.

[0023] Embodiment 2: Preparation process: Weigh the following raw materials according to weight percentage: High temperature lead-free electronic grade tin alloy powder: 90%; Diethylene glycol monobutyl ether: 15%; Hydrogenated castor oil: 8%; Polymerized rosin CLEARON 105#: 20%; Extra-grade hydrogenated rosin AX-E: 20%; Fluorocarbon surfactant FSN100: 0.5%; Triethanolamine: 0.5%; High temperature resistant thixotropic agent (ethylene bisstearamide: high performance amide wax micropowder = 1:1): 5%; High temperature resistant active agent (fluorinated surfactant: decyl tetradecanoic acid = 1:3): 2%; Organic solvent: make up to 100%.

[0024] The preparation method is the same as in Example 1, but the stirring time is 15 minutes and the intermediate stirring time is 10 minutes.

[0025] Performance parameters: Viscosity (25°C): 220±20Pa·s; Initial activation temperature: 175°C; Melting temperature range: 218-222℃; Welding strength: ≥27MPa.

[0026] Embodiment 3: Preparation process: Weigh the following raw materials according to weight percentage: High temperature lead-free electronic grade tin alloy powder: 85%; Diethylene glycol monobutyl ether: 20%; Hydrogenated castor oil: 5%; Polymerized rosin CLEARON 105#: 25%; Extra-grade hydrogenated rosin AX-E: 15%; Fluorocarbon surfactant FSN100: 1.0%; Triethanolamine: 1.0%; High temperature resistant thixotropic agent (ethylene bisstearamide: high performance amide wax micropowder = 3:1): 10%; High temperature resistant active agent (fluorinated surfactant: decyl tetradecanoic acid = 1:5): 5%; Organic solvent: make up to 100%.

[0027] The preparation method is the same as that of Example 1, but the stirring time is 10 minutes, and the mixture is paused for 1 minute after stirring for 15 minutes.

[0028] Performance parameters: Viscosity (25°C): 180±10Pa·s; Initial activation temperature: 185°C; Melting temperature range: 216-224℃; Welding strength: ≥26MPa.

[0029] Summary of embodiments: In the above three embodiments, high-temperature solder paste for chip packaging with different performance parameters was successfully prepared by adjusting the proportion of each component and the stirring conditions during the preparation process. In Example 1, by increasing the proportion of tin alloy powder, a higher welding strength was obtained while maintaining an appropriate viscosity and melting temperature range. In Example 2, the proportion of specific components in the thixotropic agent and the activator, as well as the time of intermediate stirring, were further increased, so that the solder paste exhibited good performance at a lower initial activation temperature, and the welding strength was also enhanced. Example 3 adjusts the proportion of each component in the high-temperature resistant flux, especially increases the content of fluorocarbon surfactant and high-temperature resistant thixotropic agent, so that the solder paste maintains a lower viscosity while improving its melting temperature stability and welding strength.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high temperature solder paste for chip packaging, characterized in that: The composition comprises the following components by weight percentage: High temperature lead-free electronic grade tin alloy powder: 85% to 90%, the tin alloy powder is specifically Sn96.5Ag3.0Cu0.5 alloy, with a particle size range of 10 to 30μm; High temperature resistant soldering flux: 10% to 15%, the high temperature resistant soldering flux is composed of the following raw materials in percentage by weight: Diethylene glycol monobutyl ether: 15% to 20%; Hydrogenated castor oil: 5%-8%; Polymerized rosin CLEARON 105#: 20%~25%; Special grade hydrogenated rosin AX-E: 15% to 20%; Fluorocarbon surfactant FSN100: 0.5%~1.0%; Triethanolamine: 0.5%~1.0%; High temperature resistant thixotropic agent: 5% to 10%; High temperature resistant active agent: 2% to 5%; The balance is organic solvent.

2. The high temperature solder paste for chip packaging according to claim 1, characterized in that: The weight ratio of ethylene bisstearamide to high-performance amide wax micropowder in the high-temperature resistant thixotropic agent is 1:1 to 3:1, so as to adjust the thixotropic property and fluidity of the solder paste, making it more suitable for the sub-packaging and welding of precision chips.

3. The high temperature solder paste for chip packaging according to claim 2, characterized in that: The high temperature resistant activator comprises at least one fluorosurfactant, and the weight ratio of the fluorosurfactant to decyltetradecanoic acid is 1:3 to 1:5, so as to enhance the activation and cleaning effect of the solder paste on the metal surface during the welding process and improve the welding strength.

4. The high temperature solder paste for chip packaging according to claim 3, characterized in that: The organic solvent is a butyl carbitol-terpineol mixture.

5. The high temperature solder paste for chip packaging according to claim 4, characterized in that: The method for preparing the high-temperature solder paste for chip packaging comprises the following steps: (a) adding diethylene glycol monobutyl ether, hydrogenated castor oil, polymerized rosin CLEARON 105#, super hydrogenated rosin AX-E, high temperature resistant thixotropic agent, high temperature resistant activator and part of organic solvent into a temperature controlled emulsifier, heating to 120-130° C., and stirring at a speed of 300 r / min for 10-15 minutes to prepare a primary mixed solution; (b) adding fluorocarbon surfactant FSN100 and triethanolamine to the mixed solution, continuing to stir and evacuate to a vacuum value of 0.05 MPa until the temperature returns to room temperature, thereby obtaining a soldering flux; (c) After the soldering flux prepared in step (b) is allowed to stand at a temperature of 5 to 10° C. for 24 hours, it is added to a dual planetary solder paste mixer, and high-temperature lead-free electronic grade tin alloy powder is slowly added at a temperature of 20 to 25° C. The stirring speed is controlled to be 500 r / min, and the stirring time is 20 to 30 minutes to obtain a uniform high-temperature solder paste for chip packaging.

6. The high temperature solder paste for chip packaging according to claim 5, characterized in that: In step (b), during the process of stirring and evacuating to a vacuum value of 0.05 MPa, an intermediate stirring is also performed when the temperature drops to 90°C for 5-10 minutes, and then the temperature is further lowered to room temperature to ensure that the fluorocarbon surfactant FSN100 and triethanolamine are completely integrated into the solution, thereby further improving the soldering effect and fluidity of the flux.

7. The high temperature solder paste for chip packaging according to claim 6, characterized in that: In step (c), the high temperature lead-free electronic grade tin alloy powder needs to be pre-dried before being added to the dual planetary solder paste mixer, that is, dried at 80-90°C for 2-3 hours to remove surface moisture and impurities and prevent bubbles from being generated during the mixing process, thereby improving the purity of the solder paste and the welding quality.

8. The high temperature solder paste for chip packaging according to claim 6, characterized in that: In step (c), the stirring process also includes pausing for 1 minute after stirring for 15 minutes, and then continuing to stir at the same speed for a preset time. This operation allows the tin alloy powder and the flux solution to more fully penetrate and fuse with each other, forming a more uniform and stable solder paste system.