Sn-Cu base leadless solder alloy and preparation method

Abstract

The invention relates to tin-copper-based lead-free solder alloy and a preparation method thereof. The compositions in mass percentage of the alloy are 0.1 to 1.5 percent of copper, 0.001 to 1 percent of phosphor, 0 to 6 percent of bismuth, 0 to 3 percent of zinc, and the balance being tin. The preparation method comprises the following steps: 3 to 8 percent of the phosphor and 92 to 97 percent of the tin are weighed at first and placed into a graphite crucible; the mixture is covered with protective molten salt and subjected to heat preservation for 30 to 60 minutes at a temperature of between 400 and 550 DEG C; after uniform stirring, casting is performed and tin-copper intermediate alloy is obtained; the tin-copper intermediate alloy is weighed according to the fact that the phosphor occupies 0.001 to 1 percent as calculated by the total mass of 100 percent, and 0.1 to 1.5 percent of the copper, 0 to 6 percent of the bismuth, 0 to 3 percent of the zinc and residual tin are weighed and placed into the graphite crucible; the mixture is covered with the protective molten salt and subjected to heat preservation for 40 to 80 minutes at a temperature of between 450 and 550 DEG C; and after uniform stirring, the mixture is cast into ingots. The preparation method has simple preparation technique and is easy to operate; and the product of the tin-copper-based lead-free solder alloy has the advantages of good wettability, low melting point, good mechanical property, good antioxidation, low cost and so on.

Description

Technical field: [0001] The invention belongs to non-ferrous alloy materials, and relates to a lead-free brazing material, in particular to a Sn-Cu-based lead-free solder alloy suitable for soldering of electronic components and a preparation method thereof. Background technique: [0002] Sn-Pb eutectic and near-eutectic alloys are widely used in the electronics industry because of their low price, low melting point, and good wettability to copper. With the enhancement of human awareness of environmental protection, the hazards of lead and its compounds to the environment and human health have attracted worldwide attention. The international community has issued a series of regulations to restrict or prohibit the use of Pb-containing solder. The development performance is excellent, green Environmentally friendly lead-free solder is imperative. [0003] Countries around the world have carried out a lot of research in recent years, and developed a variety of lead-free solder...

AI Technical Summary

Problems solved by technology

However, the eutectic temperature (227°C) of the binary alloy is high, the oxidation resistance and corrosion resistance are poor, and the comprehensive mechanical properties are poor. At the same time, the wettability of the Sn-Cu lead-free solder on the Cu base is not ideal. , these shortcomings greatly limit the use of this alloy. At present, Sn-Cu alloy is mainly used in wave soldering process, but it is hardly used in reflow soldering process due to its high melting point.

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