How to solder

The first thing to do is prepare everything you need for soldering: soldering iron, a small sponge, solder, pliers or tweezers, side cutters.

Plug the soldering iron into a power outlet and dampen the sponge with water. When the soldering iron heats up and begins to melt the solder, cover the soldering iron tip with solder, and then wipe it on a damp sponge. In this case, do not keep the sting in contact with the sponge for too long, so as not to overcool it.

By wiping the sting against a sponge, you remove the remnants of the old solder from it. And in the process, to keep the soldering iron tip clean from time to time, wipe it with a sponge.

Before soldering, soldered areas need to be tinned or use already tinned parts. Manual soldering is probably hundreds or thousands, and since then, almost nothing has changed in technology, resin (rosin), it was then resin, and tin and lead also did not change.

Soldering Training Technique

If you have never soldered, we suggest using one of two methods, which, as in any other method, is based on practice.

Method 1. Take 300 mm of bare wire with a diameter of 23 mm (or insulated, from which you need to remove the insulation) and cut it into 12 identical pieces of 25 mm long to make a cube out of them, fixing the connection points by soldering. It is allowed to use only pliers with long jaws, a soldering iron, solder, flux. And no other tool and fixtures. This should teach you to keep the structure stationary while it is cooling. After the cube is ready, let it cool, and then put it on your palm and squeeze your hand into a fist. If at least one of the connections is broken, it is necessary to do everything again, taking new pieces of wire.

Method 2. Cut pieces of copper wire 30-50 mm long and 2-3 mm thick. Wrap the insulated assembly wire around this wire (2–3 turns) and connect it by soldering. The tool is the same as above. This exercise should be repeated until neat, shiny, durable joints are obtained.

Basic soldering rules

When soldering, several rules must be observed, then the soldering will be reliable and accurate. It is best to use POS-61, POS-50, POS-40 solders and alcohol-rosin fluxes, it is necessary to warm the junction to such a temperature that the solder applied to it can melt.

The solder should melt due to the heat given off by the joint, the joint should be thoroughly cleaned, the joint should be fixed until the molten solder solidifies, the joint should not overheat, the solder should not be too small, there should not be too much solder.

A common mistake is that the solder is melted with a soldering iron in the hope that it will drain from the soldering iron and stick to the junction. This is a blunder! The experience of many practitioners shows that the quality of soldering is largely determined by the skill of the installer. An experienced installer: lower pressure of the soldering iron on the printed circuit board when soldering, fewer soldering, less soldering time at the given temperature of the soldering tip (internal defects on the printed circuit boards practically do not appear if the soldering time is less than 3 s). We apply a soldering iron tip to the soldered parts with an entire spatula, for efficient heat transfer. Soldering should be fast and high quality.

Do not forget about overheating of parts. It didn’t work the first time, let the radio components cool down. We select the heating time experimentally - if it is too fast, then the part will not warm up and soldering will turn out bad. We apply the flux immediately before soldering, when all preparations of the parts are completed so that it does not evaporate.

Good soldering can be seen immediately, the solder lies in a thin and even layer, glistens. No sagging, cracks and gray spots. Additional strength of the connection gives preliminary wire twisting.

Useful tips and observations

Soldering is not sticking solder, like resin or cement, to the parts to be joined. This is the process of absorption of solder into micro-gaps due to capillary phenomena and adhesion (adhesion) of solder due to surface phenomena. All these are electrostatic forces, although this is not familiar to you electrostatics, these are forces of intermolecular interaction at short distances. And here you need to clearly remember how the phenomena of wetting and capillarity work.

Firstly, if the tip end is shaken off from excess solder or wiped on a rag, then this shiny surface has a strong attraction of the molten solder. She can suck it from where. This is necessary, for example, when soldering elements or fixing soldering. To remove more solder, a piece of shielding braid from the cable is used. There is a soldering iron with a hollow at the end, which, like a spoon, is filled with solder when you touch the old solder, although now it is customary to use vacuum suction.

Secondly, if you take a little solder on the tip of the tip, then there will be nothing absorbed into the gap between the soldered parts, and there will be nothing to surround this gap around the perimeter.

Thirdly, if there is a lot of solder, then the soldering will be in the form of a drop too large and may close adjacent contacts.

Fourth, if rosin or flux is not enough at the tip of the soldering iron, as well as at insufficient temperature, then the soldering is not shiny, loose and fragile. The same thing happens when the temperature is too high, when the flux disappears before it does a good deed.

Fifthly, if there is a lot of rosin or flux in the gap, then it boils there and splashes out the solder in the form of sprays to neighboring contacts.

Sixth, with the right amount of solder and the right temperature of the soldering iron (and not too much mass of soldered parts), the solder carefully flows around the soldered contacts and is independently absorbed into the microgaps between them. That is, the shape and strength of the solder are formed themselves, as needed.

Remember that two copper parts that have been stripped even to a mirror shine will never join together (unless you rivet them or weld them). When soldering, they are connected with a thin layer of solder, which is absorbed between them only if they are already well tinned (previously covered with a thin layer of solder).

The first time you need to find out how long the soldering iron overheats. If, after five to ten minutes after switching on, it is already impossible for them to solder (the solder flies, and the tip oxidizes, it turns black), then you need an electronic temperature controller or at least a transformer with a switch or infinitely adjustable.

You can solder with an overheating soldering iron without a regulator, but then it must be turned off periodically. But the soldering iron cools quickly. In general, it is not so easy to maintain the desired temperature, so this method is rarely used, not for high-quality rations, but if necessary.

Rosin is consumed a little, but they do not stick a soldering iron into it and do not smoke the whole room. Rosin pairs are not particularly useful, so they do not solder in rooms without windows. There should be traction, but not a cooling soldering iron. For example, an open window leaves a soldering iron great, so it’s not so easy to equip yourself with a convenient and safe workplace. Ventilate after brazing or long brazing.

Almost 1 drop of solder is enough just to touch the rosin, that is, it is spent 10 times less than the solder. It is needed only for fine lubrication of the surface of two contacts.

Some strip wires with a soldering iron or a special electric roasting machine or lighter. The fluoroplastic insulation does not melt with a soldering iron, and when burning emits white smoke with a high content of fluorine and fluoride compounds. If this smoke gets in your eyes, they will cause a chemical burn.When you peel off the insulation with wire cutters, then clamp the wire with tweezers with one hand, and the other easily squeeze with wire cutters (NOT REACHING THE VEIN) and pull the insulation. If the wire cutters are sharp, then the insulation peels off easily.

It is necessary to keep the cutting pliers with the flat part directed away from the wire so that the cut off insulation abuts against this flat part, and is not clamped by the side sharpened at an angle. At the same time, you must not squeeze the nippers strongly, that is, they should in no case leave cuts and dents on the copper conductors.

If during stripping several veins come off along with insulation or you notice dents from the wire cutters, cut the wire and strip the end again. It is especially difficult to hold the fluoroplastic wire with tweezers, since the latter is always soapy to the touch. Smooth jaw tweezers may not hold the wire. Serrated tweezers can damage the insulation or veins. In this case, it is advisable not to use tweezers with thin tips, since the clamp area will be small, and you will have to press harder and maybe this will not help.

If the wire slips, it is better to wind it on the tip of the tweezers in order to increase the friction area. In any case, tweezers with wide jaws are preferable, as less traumatic wire.

Addition.

The secrets of good soldering from Boris Aladyshkin, a regular author of the site bgv.electricianexp.com

Does the design depend on the quality of the soldering, and if so, how? After all, just one soldering is enough to silence a whole receiver or amplifier. Before proceeding with the assembly or repair of printed circuit boards should be trained "on cats." In this case, it will be old printed circuit boards or separate conductors.

In no case should the soldering iron be overheated. If there is no soldering iron with a temperature setpoint, then the degree of heating can be determined by touching it with a piece of rosin: a light curly haze of a pleasant pine smell should appear. The solder should melt quite easily, and spread out at the place of soldering, forming a brilliant contour solder.

The soldered parts must be held tightly pressed together until the solder is completely crystallized. In no case, even if you are in a hurry, do not cool the solder by blowing air from your mouth or touching it with a wet (slobbering) finger. Soldering in this case will turn out loose, nostril like a dough.

The soldered parts must first be smoothed to a metallic luster and tin-coated, that is, a thin layer of solder should be applied. Tinning of printed circuit boards should be especially carefully and carefully.

The board cleaned with sandpaper should first be washed with alcohol or acetone, and then coated with a rosin-flux brush using a brush. After that, the board can be irradiated with a soldering iron, while solder does not need to be typed too much. Good results can be obtained by using a braid of a shielded wire: saturate it with solder and flux from above and press with a soldering iron and go around all the tracks.

True, some authors do not recommend taming boards, they say, they will have a artisanal appearance, they still will not work out as branded ones. Well, here, as they say, there are no comrades for the taste and color.

The overheating of the soldering iron can be determined again by touching a piece of rosin. The rosin in this case boils with spray and spews out streams of smoke, which does not curl in a thin stream, but fells in clubs. An overheated soldering iron quickly burns out, the tip turns black, the solder does not melt and spreads, but rolls into balls on the surface of the board. The board's tracks, especially thin ones, inevitably lag behind and burn out, the board becomes hopelessly damaged.

Therefore, it is best to use a soldering iron with a temperature controller, and the more precisely the set temperature is maintained, the better the quality of the soldering. The simplest power controllers on the thyristor, of course, allow you to adjust the degree of heating of the tip, but they will not support it. Imagine soldering a thin conductor to a massive part. For example, to the "ground" wire on a printed circuit board.

The soldering iron, which just soldered perfectly, cools down immediately and begins to smear the solder on the surface. If you use the thermostat, then the cooled soldering iron will quickly warm up to the set temperature, and the faster, the more its power.

Other articles from the soldering cycle:

What is soldering? Soldering Safety

How to choose a soldering iron and organize a soldering workstation

Solders and soldering fluxes