A: 1.Price: many manufacturers require that the price should not be higher than that of 63Sn/37Pn, but at present, the finished products of lead-free substitutes are 35% higher than 63Sn/37Pb. 2. Melting point: most manufacturers require a minimum solid phase temperature of 150 ℃ to meet the working requirements of electronic equipment. The liquid temperature depends on the specific application. Electrode for wave soldering: in order to successfully realize wave soldering, the liquid temperature should be lower than 265 ℃. Solder wire for manual welding: the liquid temperature should be 345 ℃ lower than the working temperature of soldering iron. Solder paste: the liquid temperature should be lower than 250 ℃. 3. Electrical conductivity.
A: lead is a toxic heavy metal, excessive absorption of lead by the human body will cause poisoning, and intake of low amount of lead may affect people's intelligence, nervous system and reproductive system. The global electronic assembly industry consumes about 60000 tons of solder every year, and it is increasing year by year. The resulting industrial waste containing lead salt seriously pollutes the environment, so reducing the use of lead has become the focus of the world's attention. Many large companies in Europe and Japan are vigorously accelerating the development of lead-free alternative alloys and have planned to gradually reduce the use of lead in electronic product assembly in 2002. It will be completely eliminated by 2004. (The traditional solder component 63Sn/37Pb is widely used in the current electronic assembly industry).
A: electronic products pursue miniaturization, the previously used perforated plug-in components can not be reduced; electronic products are more complete, the integrated circuit (IC) no longer have perforated components, especially large-scale, highly integrated IC, have to use surface patch components; product batch, production automation, the factory should produce high-quality products with low cost and high output to meet customer needs and enhance market competitiveness. The development of electronic components, the development of integrated circuit (IC), the diversified application of semiconductor materials, the revolution of electronic science and technology is imperative, chasing the international trend.
A: high assembly density, small size and light weight of electronic products, and the volume and weight of patch components are only about 1x10 of those of traditional plug-in components. after the general adopt of SMT, the volume of electronic products is reduced by 40% ~60% and the weight is reduced by 60% ~80%. High reliability and strong anti-vibration ability. The defect rate of solder joint is very low. Good high frequency characteristic. Reduce electromagnetic and radio frequency interference. This is easily automated and increases production efficiency. Reduce costs by 30% or 50%. Save materials, energy, equipment, manpower, time, etc.
