Welding & Soldering Tools

Soldering is a method of joining metal parts using a filler material (solder) which has a melting temperature below 450 °C (842 °F). more...

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Soldering is distinguished from brazing by virtue of a lower melting-temperature filler metal; it is distinguished from welding by virtue of the base metal not melting during the joining process. In a soldering process, heat is applied to the parts to be joined, causing the solder to melt and be drawn into the joint by capillary action and to bond to the materials to be joined by wetting action. After the metal cools, the resulting joints are not as strong as the base metal, but have adequate strength, electrical conductivity, and water-tightness for many uses. Soldering is an ancient technique that has been used practically as long as humans have been making items out of metal.

Applications

The most frequent application of soldering is assembling electronic components to printed circuit boards (PCBs). Another common application is making permanent but reversible connections between copper pipes in plumbing systems. Joints in sheet-metal objects such as food cans, roof flashing, drain gutters and automobile radiators have also historically been soldered, and occasionally still are. Jewelry and small mechanical parts are often assembled by soldering. Soldering is used to join lead came and copper foil in stained glass work. Soldering can also be used to effect a semi-permanent patch for a leak in a container or cooking vessel.

Methods

Soldering can be done in a number of ways, including passing parts over a small fountain in a bulk container of molten solder (wave soldering), heating assemblies by use of an infrared lamp, or by using a point source such as an electric soldering iron, a brazing torch, or a hot-air soldering tool. Recently, reflow soldering is used almost exclusively for PCB assembly, sometimes followed by a wave-soldering or hand-soldering operation for oddly sized/shaped components.

Though the base material is not melted in a soldering process, some of the base material's atoms do dissolve into the liquid solder. This dissolution process enhances the soldered joint's mechanical and electrical characteristics. A "cold solder joint" with poor properties may result if the base metal is not heated adequately to thoroughly melt the solder and cause this dissolution process to occur.

Note that the distinction between soldering and brazing is arbitrary, with the only difference being the melting temperature of the filler material. A temperature of 450 °C is usually used as a practical cutoff. Different equipment and/or fixturing is usually required since (for instance) most soldering irons cannot achieve high enough temperatures for brazing. Practically speaking there is a significant difference between the two processes -- brazing fillers have far more structural strength than solders, and are formulated for this as opposed to maximum electrical conductivity. Brazed connections are often as strong or nearly as strong as the parts they connect, even at elevated temperatures.

Read more at Wikipedia.org