What is the most convenient way to apply flux? Surely a similar question has arisen for everyone who wants to learn how to solder efficiently.
A rather original, but at the same time simple way to apply flux is to use a flux pen.
Literally, “flux pen” is translated from English as “flux pen.” Although this tool for applying flux is more similar in thickness to a marker than a pen or felt-tip pen.
The operating principle of flux pen is approximately the same as that of an ordinary felt-tip pen. The only difference is that it is filled with flux, not dye.
In addition, many flux pens have a miniature valve. It prevents the arbitrary flow of liquid flux, since in closed position It is held in place by a spring and opens only when the rod is pressed.
The harder you press on the flux pen, the deeper the rod is pushed in, tearing off the valve. Thus, by adjusting the pressure on the flux pen, you can apply flux accurately and accurately.
Flux pen is perhaps the most handy tool for soldering solar panels and SMD chips, in which the distance between the pins is even less than 1 mm.
Before buying a flux pen, pay attention to what kind of flux it is filled with, and whether it is necessary to wash off the remnants of this flux after soldering.
For soldering various elements during assembly or repair various kinds For electronic or radio components, among other things, special substances are used - fluxes. The composition of such mixtures can be very different. When soldering, both organic and inorganic fluxes are used. Such substances can be supplied to specialized stores either in the form of a powder, paste or liquid. One of the most commonly used fluxes for soldering is LTI-120.
What are they intended for?
When soldering radio and electronic parts or during hot tinning, fluxes of any type, including LTI, are used for:
- removing oxide film from treated surfaces;
- protection of metal and solders from oxidation directly during operation;
- reducing the surface tension of the molten solder.
Main technical characteristics
Flux labeled in this way may be produced by different manufacturers. But its composition, of course, is always the same. This substance was developed by the Leningrad Technological Institute. Hence its labeling - LTI.
LTI-120 is a dark liquid supplied to the market in bottles, canisters or vials. It belongs to the group of corrosive, low-temperature, activated fluxes. In some cases, the presence of a small amount of colloidal formations in the liquid is allowed.
This substance is not washed off from the surface of parts with water during operation. The temperature range of the LTI-120 flux is 160-350 degrees. When using this substance, solders can be either soft tin-lead or silver (provided that the flux is completely removed at the end of the work). The temperature of maximum activity of this product is 250...300 °C.
Soldering flux LTI-120, therefore, does not dissolve in water. At the same time, it belongs to the class of neutrals. That is, after soldering, it is usually not necessary to remove its remains. But if necessary, you can, of course, wash it off from surfaces. For this you need to use acetone or alcohol. Some craftsmen wash off this flux simply with cheap vodka.
What materials can you work with?
For what parts is soldering allowed using this flux? LTI-120 can be used when working with elements made from:
- of stainless steel;
- zinc;
- nichrome;
- lead;
- cadmium;
- palladium;
- copper and its alloys.
Very often this substance is also used for soldering silver.
LTI-120: flux composition
This substance intended for soldering is manufactured using the following materials:
- pine rosin grade “A” (20-25%);
- triethanolamine (1-2%);
- diethylamine hydrochloride (3-5%);
- ethyl alcohol (90-95%).
Flux LTI-120, therefore, does not have a particularly complex composition. Cooking it at home, of course, is not very easy. But many craftsmen, if it is not available in specialized stores, select the appropriate components and mix such a flux, including on their own. This is explained primarily by the fact that the actual technology for preparing this substance is not particularly complicated.
Price
Among the advantages of LTI flux, consumers, among other things, include its low cost. Most often, this soldering liquid is supplied to stores in 30 ml bottles. There are also 20 ml bottles of this product on sale. They usually come with a brush. Soldering flux LTI-120 in such a container costs only about 30-50 rubles.
Industrial enterprises can purchase this substance in 500 ml bottles. One such container costs approximately 300-550 rubles. depending on the manufacturer. Sometimes this flux is sold in large canisters up to 5 liters. In such a container, the substance costs about 2000-2500 rubles.
Consumer Reviews
In addition to its low cost, consumers attribute the advantages of the LTI-120 flux, first of all, to the fact that in most cases it comes with an easy-to-use brush. Thus, the master does not have to look for such a tool separately. Working with the LTI flux brush is actually very comfortable. Also, many masters praise this substance for the fact that it does not conduct electricity. It is believed that they are very convenient for soldering not only printed circuit boards, but also just wires. Tinning using this substance, according to many craftsmen, is much more convenient than using the same alcohol rosin.
Flux LTI-120 also earned good reviews from consumers because it does not have to be washed off after work. If necessary, it is very easy to remove from the material with alcohol.
Another undoubted advantage of this flux is that it is usually supplied in non-spillable bottles. That is, during operation there is no special need to monitor the stability of the container with it.
According to most consumers, this flux has virtually no disadvantages. Even a volume of 20 ml is considered by most masters to be very convenient. This bottle doesn't take up much space in your toolbox. At the same time, LTI-120 flux lasts for a long time. Some of the disadvantages of this substance, experts attribute only to the fact that it dries too quickly.
Flux LTI-120: use at home
When using this substance, it should be borne in mind that its residues may have a corrosive effect on copper elements after soldering. They do not affect tin, nickel and silver coatings in this way. Residues of LTI-120 flux, although slightly, reduce the resistance of products.
When working with this substance, as with any other chemical, of course, safety precautions should be observed. Under no circumstances should flux get into the stomach, mucous membranes or eyes. When soldering using this substance, be sure to use a brush. If flux gets on your skin, the affected area should be thoroughly rinsed under running water. cold water with soap.
How is flux made?
In the production of this substance, enterprises use the following materials:
- Triethanolamine TU 6-02-916-79 (2 g).
- Pine rosin GOST 19113-84 (25 g).
- Ethyl alcohol GOST 18300-87 (68 g).
- Diethylamine hydrochloride TU 6-09-5395-88 (5 g).
Cotton wool GOST 5556-81 and canvas stitching fabric TU 8399-001-48212332-03 are also used.
The tools and equipment used are:
- fume hood;
- scales and spatula;
- mortar and pestle;
- household clock.
The flux itself is prepared using the following technology:
- rosin is weighed on scales and ground into powder;
- ethyl alcohol is weighed and added to the rosin;
- everything is thoroughly mixed;
- triethanolamine and diethylamine hydrochloride are added to the resulting solution;
- everything is mixed well again.
The solution obtained in this way is kept for 20-30 minutes, and then bottled with airtight lids.
How flux is checked at enterprises
Of course, before hitting store shelves, this substance undergoes the most thorough quality control at the factory. To do this, first take a small sample of the solution. Next, the flux is applied thin layer onto a glass plate. Then the drying time at 30 °C is determined. If after 60 minutes the surface is still wet, the solution is rejected.
To determine the amount of non-volatile substances, the sample is placed on a scale with an accuracy of 0.1 g. 9-10 grams of the substance are poured into a porcelain cup. Dry the flux in it for 3 hours at a temperature of 100 °C. Next, weigh the container and compare the result with that obtained earlier. The calculation is performed using the formula: % non-volatile = (b - a) × 100/s, where a is the weight of the cup, b is the weight of the container with the dry residue, c is the initial weight of the flux being tested.
Also, using special technologies, before delivery to stores, the color of the substance and its reaction to phenolphthalein and methyl orange are checked. When mixing the latter, the flux should turn yellow. When tested with phenolphthalein, on the contrary, the substance should not change its color in any way. At pink color the flux is rejected.
Storage rules
Flux LTI-120, the use of which is also allowed at home, however, belongs to the class of fire and explosive substances. Therefore, it should be stored correctly. This solution should only be kept in a hermetically sealed container. Do not place a bottle of this product near open source fire or under direct fire Sun rays. After performing work with this substance, it is advisable to ventilate the room.
Flux LTI Lux
This modification also deserves good feedback many masters. The performance characteristics of the LTI-120 Lux are simply excellent. Consumers praise it primarily because it is devoid of the main drawback of the base substance. This variety dries much more slowly. This property of LTI-120 Lux is primarily due to the fact that it is made on the basis of water. This modification does not contain any volatile solvents.
Thus, there is no ethyl alcohol in LTI-120 Lux. But all the other components in it are exactly the same as in the base solution. In addition to soldering itself, this new flux can also be used for cleaning parts. With its help, you can easily and quickly remove any dirt from the boards. This substance is less dangerous in work than flux 120. Some craftsmen even wash their hands with it.
In order to save on material, LTI-120 Lux can be spread in a very thin layer. The difference in its operation compared to the 120 modification lies primarily in the fact that it hisses quite loudly and also steams a little. But after using it, it is impossible to see any rosin residues on the boards.
Application of various types of liquids to printed circuit boards, or somewhere else, you can make it much more convenient using special devices. And despite the great variety of industrial devices and equipment, handmade no one has canceled yet.
Do-it-yourself marker-dispenser for flux:
A marker or felt-tip pen whose service life has long expired was previously refilled with ink and alcohol, but is now simply thrown away as unnecessary, without thinking that it can be used as a reservoir for something else. For example, I made myself an excellent marker dispenser for F5 flux.
Well, in short... the name of the device speaks for the idea itself, and like everything ingenious, it’s quite simple. If you have a couple of felt-tip pens, markers lying around (I don’t know, but... well, maybe capillary pens and proofreaders will work too), then don’t rush to throw them away.
As a radio amateur, I am pleased with this little thing, and I proudly tell you how to make a dispenser for flux from an ordinary felt-tip pen:
To begin, take an alcohol-based marker or felt-tip pen (preferably an empty one).
Alcohol based marker
And we completely disassemble it into its component parts. Naturally, it is better to do this with gloves, holding a container of water nearby so that you can immediately rinse it there.
Special attention Pay attention to washing the rod. And the fibers themselves, which contained ink, can simply be thrown away; I personally didn’t need them. And then you need to dry all the marker parts well.
Then you take ordinary cotton wool and press it into a transparent tube where the fibers were, you just need to leave a little space at one end of the tube.
Then we simply take and saturate the cotton wool with the liquid that you are going to apply (I poured flux into it). If you leave a little space and do not fill the tube with cotton to the top, then impregnation is much more convenient. Well, after all that, you need to collect the marker and return everything as it was. I also recommend immediately sticking a tag on the marker with the name of what you uploaded there.
Wait a little while the marker rod is saturated with flux and you can safely smear whatever you want with it. From personal experience I will say that it is very convenient device, especially when using active liquid fluxes. Such a container does not leak and at the same time is always at hand, you can apply flux evenly and accurately, even in hard-to-reach places.