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Fluxes for brazing

   This auxiliary materials for reliable soldering. They should
1) dissolve and remove oxides and impurities from the surface of the solder metals
2) defend during the soldering process the metal surface and the molten solder from oxidation
3) reduce the surface tension of the molten solder,
4) to improve the spreadability of the solder and wetting them connected surfaces.
  
The effect of the metal exposed to solder, fluxes are divided into several groups.

1. Active, or acid fluxes. They are prepared on the basis of active substances: hydrochloric acid. chloride and fluoride compounds metals etc. These fluxes, rapidly dissolve the oxide film on the metal surface, which ensures good adhesion, and therefore, high mechanical strength of the junction. The remainder of the flux after soldering causes intense corrosion of the weld and the base metal. Therefore, these fluxes are applied only in the case when possible by a thorough rinsing and complete removal of flux residues.
During Assembly soldering electroradiation application of active fluxes is unacceptable.

2. Acid-free fluxes. The so-called rosin and fluxes, prepared on its basis with the addition of inactive substances (alcohol, glycerin).

3. Activated fluxes. The so-called fluxes, prepared on the basis of rosin with the addition of activators small amounts of hydrochloric acid or phosphate of aniline, salicylic acid, hydrochloric acid diethylamide, etc. the High activity of some activated flux allows soldering without prior removal of oxides after degreasing.

4. Corrosion fluxes. It fluxes based on phosphoric acid with the addition of various organic compounds and solvents, as well as fluxes based on organic acids. The residues of these fluxes do not cause corrosion.
SENSORS OF PHYSICAL PARAMETERS
   Fluxes and health
It is impossible to imagine radio, which would not keep in the hands of the soldering iron. Of course, every radio Amateur in soldering is flux, fortunately, there are hundreds of types. And of course, sooner or later the question arises to what extent these fluxes can harm the health.
Work related to soldering and tinning shall be conducted in specially equipped and pre-prepared areas. There must be a ventilation system. The ventilation unit should be equipped with audible and light signaling.

All work under a fume hood or with the means of protection? I highly doubt it. Therefore, I propose to consider the components of neoterik flux and solder, which can harm the health.

Rosin. One of the oldest and most popular fluxes. Flux predstavljaet a mixture of various resin acids and their isomers, the bulk of which is accounted for abietinum acid. The substance is relatively safe, but it is not all that simple. Prolonged inhalation of air containing particles of rosin exceeds the permissible level, leads to the development of allergic reactions, often turning into asthma. When soldering an overheated soldering iron rosin falling apart. The products of the decay of many substances with varying degrees of harm. This acid: Valerian, gatilova, Caprylic, pelargonia, acetic, pinolin consisting of cumene, zimola, methylcyclohexane, dimethylcyclohexane and abietin, abimip, text - raymarin, hydrometry and hydrophilanthropy. Are substances with low toxicity that can, however, cause allergies, asthma, and mucous membranes. Synthetic and gidrirovanny resin contain almost no abietinum acid, therefore it hardly causes allergic reactions, by heating mainly sublimated and does not decompose. In the end, this flux is less harmful. The only negative - this rosin is ten times more expensive than ordinary pine.

One of the most massive suppliers of fluxes is China. The composition is not specified anywhere, what's the most specified country of origin USA or Japan. There are some data on these fluxes, obtained in the result of the analysis.

Amtech RMA-223. Ingredients: Petrolatum technical, stearic acid, palmitic acid, higher fatty alcohols. These substances are quite safe. In some samples found in the ethylene glycol is quite toxic component of antifreeze and brake fluids.

Amtech NC-559-ASM KINGBO RMA-218. As it turned out, the qualitative composition of these fluxes are very close, the only difference in percentage content of major components. Was discovered Higher carboxylic acids, higher fatty alcohols, esters of stearic and linoleic acids, rosin resins of natural or synthetic origin. These substances are non-toxic flux, but among them were phenol, a toxic substance of the second class danger. As it turned out, this is not surprising. In order for resin had the desired properties, such as ductility, low oxidation capacity, the lack of propensity to crystallization, it modifies. One of the inexpensive, simple and effective ways of modification of rosin with phenol.While rosin and even significantly lightened . Even if the production of the obtained product flux is cleaned from the excess of phenol, it is still part of it remains attached to the rosin acids. In the production of synthetic resins which are used in the manufacture of fluxes, this chemical is also widely used.

When soldering phenol is released and vapours into the air. It is worth noting that the presence of the soldering process does not harm, on the contrary, carbolic acid, also known as phenol, has a significant fluorous action. And now about the danger and flux of this substance. Chronic exposure to phenol causes Central nervous system damage, there are nervous disorders, dizziness, headache. Also affects the kidneys, liver, respiratory organs and heart. There are assumptions about the carcinogenic effects of phenol. In Russia, the modification of rosin with phenol-received, but widely used in China, South Korea, India and other countries.

Stand to note that small concentrations of phenol has a distinctive, slightly sweet smell, and some of the related soldering flux, the authors point to him, not knowing about the toxicity. The question arises, and such fluxes know about the phenol? And if so, why not warn? Of course you do. surely not everyone has forgotten the scandal involving children's toys made of toxic plastics from China. Is it any wonder the Chinese flux.

GOOT BS-850. The flux contains rosin high purity 2-methyl-2, 4-pentanediol (gexilenglikole), the activator. It gexilenglikole is the main component, its weight is not less than 40%. A substance that causes dermatitis; irritation of eyes, skin and mucous membranes. Capable of hitting the respiratory system and the liver. Affects the Central nervous system, causing weakness, memory impairment. It should be noted that this ingredient firm IT applies in most of its fluxes.
Source: http://cxem.net/