Aluminum borate crystal whisker reinforced low-temperature unleaded composite soldering paste and preparation method thereof

Abstract

The invention provides an aluminum borate crystal whisker reinforced low-temperature unleaded composite soldering paste and a preparation method thereof, relating to a soldering paste and a preparation method thereof, which solve the problem that extremely serious coarsing of tissues and an intermetallic compound after high-temperature aging exists in the traditional low-temperature unleaded solder. The aluminum borate crystal whisker reinforced low-temperature unleaded composite soldering paste is prepared from aluminum borate crystal whiskers, Sn-58Bi powder and rosin type scaling powder. The method comprises the steps of: weighing raw materials, filtering and drying the aluminum borate crystal whiskers after stirring, putting the aluminum borate crystal whiskers together with the Sn-58Bi powder, 12-hydroxystearic acid and ZrO2 grinding balls into a ball milling jar for ball milling to obtain composite solder powder; and stirring the composite solder powder and the rosin type scaling powder to obtain the soldering paste. According to the invention, the tissues are obviously refined, the tensile strength of the prepared soldering paste is 59.4-62.0 MPa, the 0.2% yield strength ofthe prepared soldering paste is 51.9-55.2 MPa, the percentage elongation of the prepared soldering paste is 33.1-56.5%, and the shear strength of a BGA (Ball Grid Array) soldering point is increased by 14-29.3%.

Description

technical field [0001] The invention relates to a solder paste and a preparation method thereof. Background technique [0002] In recent years, due to the toxicity of lead, the commonly used Sn-Pb solder has been gradually replaced by tin-based lead-free solder. The research results show that the green lead-free solder that is most likely to replace tin-lead solder is based on Sn, and a binary or multi-element alloy system of Sn is formed by adding alloying elements such as Ag, Cu, Bi, Zn, and In. To meet the organizational and performance requirements of solder. Among them, Bi and In are important elements to reduce the melting point of lead-free solder. However, because In is expensive and its use is limited, Sn-Bi alloy is undoubtedly a typical representative of low-temperature solder. [0003] Sn-58Bi eutectic solder has a low melting point, good fluidity and thermal fatigue properties, and is an ideal material for low-temperature lead-free solder, but because Bi itse...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that existing low-temperature lead-free solder has extremely serious microstructure and intermetallic compound coarsening after high-temperature aging, which reduces the plasticity of the coarsening position, resulting in poor performance of the brazing joint and even peeling off, and provides A kind of aluminum borate whisker reinforced low-temperature lead-free composite solder paste and preparation method thereof

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