Aluminum and its alloys are only inferior in strength to steel, but they are very convenient in processing, have a decent appearance and possess such excellent qualities as thermal conductivity and electrical conductivity. However, along with these properties, there is the complexity of their soldering. The question of how to solder aluminum is given not only by beginners, but also by those who are not hampered by the soldering of copper, brass and steel.
Aluminum soldering process is difficult, so you need to know all its technology.
It is not easy to work with aluminum because of its ability to instantly oxidize in air, as a result of which the surface is covered with a thin film of A12O3 oxide, which is highly resistant to aggressive media. Therefore, special mercury fluxes or replaceable tips for soldering irons are used, or, depending on the soldering method, oxide is removed in various ways.
Before soldering aluminum, they resorted to mechanical removal of the film, clearing the workplace with a file, but the contact of aluminum with water or air leads to the initial state - the appearance of the same film.
For soldering aluminum, you can use a special flux.
Experts advise to clean the place of soldering with a brick or sand, without removing dust, but apply molten rosin directly to it, then rub it with a soldering iron, strongly pressing a tip. This will help the destruction of a thin film formed before the application of rosin.
Also, the brushed aluminum is filled with rosin and sprinkled with iron nail filings obtained in the process of sawing. Further, a soldering iron must be tinned surface, carefully rubbing the sting. Iron crumb will destroy the film, rosin also prevent the formation of a new film.
Chemical stripping methods
It is important not to allow the cleaned aluminum to contact with the air, for which the place of soldering is filled with flux or rosin, while heating it. Often, small items, such as wires, sink directly into rosin or into flux poured into a container.
In addition to the mechanical method of removing oxide, there are several so-called chemical methods.
Cleaning aluminum before soldering can be done with the help of a copper cup.
Cleaning with copper sulfate. The point where you need to make a solder, cleaned with a needle file, moistened with two or three drops of copper sulfate solution. The aluminum base is connected to the negative pole of the battery or battery, a small piece of copper wire stripped and connected to the positive pole is lowered into solution without touching the base. After turning on the 4.5-volt battery, a copper deposit is formed on the aluminum after a short period of time. The desired part is then soldered to the dried copper.
The use of abrasive powder. Preparing a liquid paste by mixing powder and transformer oil, which is applied to the cleaned surface and then rubbed with a soldering iron until a tin layer appears.
Another way - transformer. The product is connected to its minus, the copper wire containing several wires is connected to the plus. After the circuit closes, aluminum micro-welding with copper will occur. Soldering acid is used to speed up the process.Back to table of contents
Application of fluxes and solders
Soldering iron design.
For soldering large parts, such as cooling radiators, soldering irons with high power (100-200 W) are used, 60-100 W soldering irons quite successfully cope with small elements. Of course, the place of solder does not have a special fortress, but this is not required.
At home conditions for soldering aluminum suitable fluxes F-64, FTBF-A, FIM. Of course, you can use aspirin, technical vaseline, solid oil, soldering fat, and stearin as a flux.
Using special active fluxes, it is easier to solder, they do well with the oxide film, provided that the heating temperature is 250-360 ° C.
Solder is distributed over the entire surface of the joint, which leads to a solid connection of the parts. The flux must be removed using solvents, alcohol or a special liquid. The convenience of using such fluxes is that they are also used for brazing nickel, copper and steel.
As a rule, alloys from 2 parts of zinc and 8 parts of tin, or 1 part of copper and 99 parts of tin, or 1 part of bismuth and 30 parts of tin are used for soldering aluminum. Conventional solders PIC. 40 and pic. 60 also cope with the task.
Small holes (with a diameter of not more than 7 mm) in an aluminum dish can be soldered without a soldering iron. The enamel around the hole should be repaired by 5 mm, lightly tapping with a hammer. Now, using a file or emery paper, polish the metal using shreds of rosin or soldering acid, put a piece of tin in the pot on the hole and heat it over the spirit lamp, which provides point heating without destroying the remaining enamel. The metal, melting, completely closes the hole.
So, having the desire, it is possible to solder aluminum at home.