<P> Very thin layer of zinc can be used for joining aluminium parts . The parts have to be perfectly machined, or pressed together, due to the small volume of filler metal . At high temperature applied for long time, the zinc diffuses away from the joint . The resulting joint does not present a mechanical weakness and is corrosion - resistant . The technique is known as diffusion soldering . </P> <P> Fluxless brazing of copper alloys can be done with self - fluxing filler metals . Such metals contain an element capable of reaction with oxygen, usually phosphorus . A good example is the family of copper - phosphorus alloys . </P> <P> In soldering of metals, flux serves a threefold purpose: it removes any oxidized metal from the surfaces to be soldered, seals out air thus preventing further oxidation, and by facilitating amalgamation improves wetting characteristics of the liquid solder . Some fluxes are corrosive, so the parts have to be cleaned with a damp sponge or other absorbent material after soldering to prevent damage . Several types of flux are used in electronics . </P> <P> A number of standards exist to define the various flux types . The principal standard is J - STD - 004 . </P>

What kind of flux is used in soldering electronic components
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