How to Buy the Right Solder for Your Electronics Projects
Soldering is used in electronics to connect metals. Solder, the soft metal that's used to create solder joints, is an alloy of tin and lead. Most solders are 60 percent tin and 40 percent lead, but that ratio may vary a bit.
Although solder is wound on spools and looks like wire, it's actually a thin hollow tube that has a thin core of rosin in the center. This rosin, called the flux, plays a crucial role in the soldering process.
It has a slightly lower melting point than the tin/lead alloy, and so it melts just a few moments before the tin/lead mixture melts. The flux prepares the metals to be joined by cleaning and lubricating the surfaces to be joined.
Solder comes in various thicknesses, and you'll need to have several different thicknesses on hand for different types of work. Start with three spools: 0.062″, 0.032″, and 0.020″. You'll use the 0.032″ for most work, but the thick stuff (0.062″) comes in handy for soldering larger stranded wires — and the fine solder (0.020″) is useful for delicate soldering jobs on small components.
Solder is about 40 percent lead, and as you probably know, lead poisoning is a very real health hazard. Fortunately, your actual exposure to lead while soldering is pretty small. The smoke that often puffs up when you're soldering is from the rosin flux, not from the lead or tin melting.
Even so, it's a good idea to always work in a well-ventilated area, and to wash your hands after soldering to remove any residual lead.
You can purchase lead-free solder, although it's considerably more expensive than regular solder made from lead and tin. However, lead-free solder is more difficult to work with than normal solder. If you're concerned about the long-term effects of working with leaded solder, switch to lead-free solder but only after you've become proficient at working with leaded solder.
Do not buy acid-flux solder, which plumbers use to solder pipes. The acid in this type of solder will destroy your electronics projects.