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High-reliability low-temperature lead-free solder paste and preparation method thereof

A lead-free solder paste, reliable technology, applied in the direction of manufacturing tools, welding equipment, metal processing equipment, etc., can solve the problems of poor thermal fatigue reliability, easy to fall off solder joints, poor wettability, etc., to achieve thermal fatigue resistance Good performance, less post-soldering residue, continuous and smooth printing process

Active Publication Date: 2016-07-06
广东中实金属有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the actual use process, the above two types of solder pastes have obvious deficiencies and cannot well meet the needs of actual use. Specifically: 1. Sn-Bi58 has a low melting point and good wettability, but Bi itself is brittle. The high content of Bi makes the Sn-Bi solder have high brittleness. After making solder paste, this situation still exists. After soldering, the solder joint has low strength and poor mechanical properties. Under the action of external force, the solder joint is easy to fall off. Thus making electronic devices and equipment invalid
2. Sn-In solder paste has low melting point, good electrical and thermal conductivity, and low toxicity, but there are still problems such as poor thermal fatigue reliability, poor wettability, and cleaning after soldering.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Weigh 0.35 kg of triethylene glycol methyl ether, 0.47 kg of rosin, 0.05 kg of malonic acid, 0.07 kg of suberic acid, and 0.06 kg of hydrogenated castor oil. Add triethylene glycol methyl ether into the container, raise the temperature to 100°C, and stir for 3 minutes. Then add rosin, disperse the rosin with a high-speed disperser, and dissolve it completely in the solvent. After the solution is clear and transparent, cool down to 90°C, add malonic acid and suberic acid, and disperse for 8 minutes with a high-speed disperser to make the active agent Fully disperse in the liquid, let it stand for 5 minutes, then add hydrogenated castor oil, disperse with a high-speed disperser, so that the thixotropic agent is completely dissolved in the flux, then take out the dispersion head, and let it stand for 8 hours to obtain the required of flux.

[0021] Stir the flux with a spatula for 1 minute, then weigh the flux and solder powder in a weight ratio of 90:10. Put the weighed...

Embodiment 2

[0023] Weigh 0.18 kg of propylene glycol methyl ether, 0.24 kg of ethylene glycol ether, 0.44 kg of rosin, 0.05 kg of glutaric acid, 0.03 kg of citric acid, and 0.06 kg of ethylene bis stearic acid amide. Add propylene glycol methyl ether and ethylene glycol ethyl ether into the container, raise the temperature to 95°C, and stir for 4 minutes. Then add rosin, use a high-speed disperser to disperse the rosin, and make it all dissolve in the solvent. After the solution is clear and transparent, cool down to 80°C, add glutaric acid and citric acid, and use a high-speed disperser to disperse for 5 minutes to fully dissolve the active agent. Disperse in the liquid, let it stand for 10 minutes, then add ethylene bis stearic acid amide, disperse with a high-speed disperser, so that the thixotropic agent is completely dissolved in the flux, then take out the dispersing head, and let it stand for 10 hours to obtain this product Invent the required flux.

[0024] Stir the flux with a s...

Embodiment 3

[0026] Weigh 0.38 kg of ethylene glycol methyl ether, 0.41 kg of rosin, 0.15 kg of adipic acid, 0.02 kg of methyl hydrogenated castor oil, and 0.04 kg of ethylene bis stearic acid amide. Add ethylene glycol methyl ether into the container, raise the temperature to 90°C, and stir for 5 minutes. Then add rosin, disperse the rosin with a high-speed disperser, and make it completely dissolved in the solvent. After the solution is clear and transparent, cool down to 85°C, add adipic acid, and disperse with a high-speed disperser for 10 minutes to fully disperse the active agent in the liquid. In the middle, let it stand for 3 minutes, then add methylated castor oil and ethylene bis stearic acid amide, and disperse it with a high-speed disperser, so that all the thixotropic agent is dissolved in the flux, then take out the dispersing head, and let it stand for 12 hours. Obtain the flux required by the present invention.

[0027] Stir the flux with a spatula for 2 minutes, then weig...

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Abstract

The invention discloses a high-reliability low-temperature lead-free solder paste and a preparation method thereof. The high-reliability low-temperature lead-free solder paste is prepared by mixing solder powder and flux according to a weight ratio of 88.5-90.0:10-11.5. The solder powder is composed of, by weight, 48-56% of Sn, 1.0-1.4% of Ag, 0.1-0.15% of rare earth Ge / Nd and the balance In. In the selected raw materials, solder powder alloy is low in melting point, excellent in mechanical property and thermal fatigue resistance and capable of meeting high reliability in use of the solder paste in a low-temperature environment; the flux is low in boiling point and capable of meeting the requirement that other components of the flux are dissolved by a solvent in a soldering process, and the flux is basically volatilized to reduce after-soldering residues after soldering is finished; an active agent with a low melting point can guarantee greatest functions in the soldering process to realize removal of an oxide film of a substrate, reduction of surface tension of soldering flux and promotion of moistening of the solder paste and the substrate; a thixotropic agent can guarantee freeness of sedimentation and layering in a solder paste storage process and continuity and smoothness in a printing process.

Description

technical field [0001] The invention relates to the field of connecting materials, in particular to a high-reliability low-temperature lead-free solder paste and a preparation method thereof. Background technique [0002] Solder paste is widely used as a connecting material for electrical components. Different components have different requirements for solder paste due to different use requirements, working environments, and electrical characteristics. For the LED industry and some electronic component chips, electronic materials and substrates that cannot withstand high-temperature soldering, low-temperature solder paste is mainly used to complete the connection process. Therefore, there is an increasing demand for low-temperature solders in the market. [0003] Solder paste is a homogeneous mixture of solder and flux that matches it. The low-temperature solder pastes currently used in the market are mainly Sn-Bi series and Sn-In series. For the eutectic alloys of these ...

Claims

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Application Information

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IPC IPC(8): B23K35/26B23K35/362
CPCB23K35/262B23K35/362
Inventor 方瀚宽方喜波梁静珊范欢方瀚楷
Owner 广东中实金属有限公司
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