The production and maintenance process of electronics, hardware, clocks, toys, accessories and other industries are inseparable from soldering, so lead-free tin bar
soldering materials are indispensable in these jobs. The melting point of solder varies with the ratio of tin to lead, and the melting point of tin-lead alloys is lower than that of any other alloy. High-quality solder has a tin-lead ratio of 63% tin and 37% lead. The melting point of this proportion of solder is 183°C. Some poor-quality solders have higher melting points, and the solder joints are rough and slag-like after solidification, which is due to the high lead content in the solder.
Whether a certain metal can be welded and whether it is easy to weld depends on two factors: first, whether the solder can form a compound with the weldment; second, whether there is rust on the welding surface that affects the welding fastness. When soldering, solder can react with most metals (such as gold, silver, copper, iron) to form a rather hard and brittle metal compound, which can make the solder and solder firmly bond together, but some Metals (such as titanium, silicon, chromium, etc.) cannot react with solder, so these metal materials cannot be soldered with solder.
A brief introduction to the commonly used solder materials, hoping to help beginners.
1. Add copper solder
When soldering very thin copper wires, in order to prevent the corrosion of thin copper wires by solder and flux, copper-added solder should be used, and its proportion is: 50% tin, 48.5% lead, 1.5% copper. 2. Add silver solder
Silver-added solder is also commonly used in electronic products. It is often used in the soldering of electronic products with high signal requirements or some silver-plated components. Its proportion is generally: tin 62%, lead 36%, Silver 2%.
3. Add antimony solder
Since the tin-lead alloy will recrystallize in an extremely cold environment, the solder at this time is no longer a metal but is crystalline and very brittle. This crystallization change will cause the solder joint to expand and break and desolder. Therefore, the recrystallization of the solder can be prevented by incorporating an appropriate amount of antimony into the solder.
4. Add cadmium solder
In some occasions that are sensitive to temperature, cadmium-added solder can be used. Its melting point is 145 °C, so it is called ultra-low temperature solder. Its proportion is: 50% tin, 33% lead, and 17% cadmium, but due to Cadmium is highly toxic, so it should be used with caution,
Solder is the medium that connects the components and the circuit board. The solder we often use in the installation and maintenance of electronic circuits is composed of two metals, tin and lead, which are fused in a certain proportion. The proportion of tin is slightly higher.
Pure lead Pb (Plum-bum) is blue-gray, soft and heavy, ductile, easy to oxidize, and toxic. The melting point of pure lead is 327°C. Pure tin Sn (Stan-num) is silver-white, shiny, and ductile. It is not easily oxidized in the air. Its melting point is 232 °C. Tin can be alloyed with most metals. But the material of pure tin is brittle. In order to increase the flexibility of the solder and reduce the melting point of the solder, another metal must be fused with the tin to ease the performance of the tin.
When tin and lead are fused in proportion to form lead-free tin bar-lead alloy solder, at this time, its melting point becomes lower, it is easy to use, and can be combined with most metals.