Brazing and Soldering
Brazing and soldering can both be made more efficient by applying induction heating. Induction heating process can produce the cleanest, most reliable joints possible for your part. Induction heating systems can be easily integrated into your line with continuous automatic feeds and may be designed to provide heat at multiple locations simultaneously.
Brazing is a joining process whereby a non-ferrous filler metal and an alloy are heated to melting temperature (above 450°C; 800°F) and distributed between two or more close-fitting parts by capillary action. At its liquid temperature, the molten filler metal interacts with a thin layer of the base metal, cooling to form an exceptionally strong, sealed joint due to grain structure interaction. The brazed joint becomes a sandwich of different layers, each metallurgically linked to each other. Common brazements are about 1/3 as strong as the materials they join, because the metals partially dissolve each other at the interface, and usually the grain structure and joint alloy is uncontrolled. To create high-strength brazes, sometimes a brazement can be annealed, or cooled at a controlled rate, so that the joint’s grain structure and alloying is controlled.
Soldering is a method of joining metal parts using an alloy of low melting point (solder) below 450 °C (800 °F). Heat is applied to the metal parts, and the alloy metal is pressed against the joint, melts, and is drawn into the joint by capillary action and around 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 articles out of metal.
Soldering can be done in a number of ways, including passing parts over a bulk container of melted solder, using an infrared lamp, or by using a point source such as an electric soldering iron, a brazing torch, or a hot-air soldering tool. Flux is usually used to assist in the joining process. Flux can be manufactured as part of the solder in single or multi-core solder, in which case it is contained inside a hollow tube or multiple tubes that are contained inside the strand of solder. Flux can also be applied separately from the solder, often in the form of a paste. In some fluxless soldering, a forming gas that is a reducing atmosphere rich in hydrogen can also serve much the same purpose as traditional flux, and provide the benefits of traditional flux in re-flow ovens through which electronic parts placed on a circuit card are transported for a specific period of time.