When soldering it is necessary to use gumboils – special substances which help solder to spread in the place of soldering. The main gumboils – rosin and acid. Rosin is usually used when soldering copper and silver, and acid – in more difficult cases. What acid to use and how to solder with its help?
1. The choice of acid depends on type of metal or alloy. For soldering of iron, including zinced, apply so-called soldering acid – zinc chlorate solution. For soldering of stainless steel use orthophosphoric acid and special multicomponent gumboils. Aluminum is not soldered at all as there are no available gumboils for dissolution of oxidic film of aluminum. Acid is not suitable for soldering of printed circuit boards as emergence of corrosion and short circuit between conductors is possible.
2. If you have decided to use soldering acid, then it can be bought ready prepared (it is on sale in the form of paste, and it is possible to make independently). Take about 100 ml of hydrochloric acid, put pieces of the zinc taken, for example, from batteries there. There will be chemical reaction at which hydrogen will be emitted therefore such work needs to be carried out in the aired room far from fire. When vials of hydrogen cease to rise, solution needs to let stand to transparency, and then accurately to pour in bubble. Soldering acid is ready.
3. Before soldering smooth out surfaces file or abrasive paper to save them from pollution.
4. Apply on the place of soldering acid, it can be done with brush, then by means of the heated soldering iron cover the accustomed to drinking surface with solder – tin or its alloy. If solder does not want to lay down exactly on the right place, it is necessary to process repeatedly the site acid.
5. Accurately solder surfaces. During the work with the heated soldering iron you remember rules of the equipment of fire safety and do not litter workplace with easily flammable objects.
6. After work neutralize acid by means of alkali, for example, of soda solution, and then wash out the place of soldering to remove residues of acid. As gumboil in rare instances acetilsalicylic acid is also used.