What are Solder Bars?
Solder as we know, is the fusible filler material used to join pads or holes of a PCB with the components leads while melting. Solder is usually available in spools of wire or in bars. The solder bar is the solid form of the solder alloy that joins workpieces together. Solder Bar is made solely from high purity metal, produces a low proportion of dross and it is suitable for dip and wave soldering. Mostly, lead-free solder bars are used in the electronics soldering process.
Different combinations of tin, lead and other metals are used to create the solder bars. This is because each metal will create strong bond with a certain soldering bar. The combinations used depends on the desired properties. The most popular combinations are SAC (Tin(Sn)/Silver(Ag)/Copper(Cu)) alloys and Sn63Pb37 (Sn63A) which is 63% tin, 37% lead. Higher tin compositions result into higher corrosion resistant solder, but also, raise the melting point. A composition is 11% tin, 37% lead, 42% bismuth, and 10% cadmium is also used. This combination provides an advantage on soldering components that are sensitive to heat as it has a low melting point.
In a wave soldering process, bulk soldering of printed circuit boards is carried out. The circuit board is passed over a pan of molten solder in which a pump produces an upwelling of solder that looks like a standing wave. That molten solder wave is obtained by melting the solder bars. In both wave soldering and dip soldering techniques, the flux is applied separately. The flux is sprayed under the bottom side of a PCB that needs to be wave soldered.
Dip soldering is just a manual correspondent of automated wave soldering. The only required equipment is a small tank containing molten solder. A PCB with mounted components is dipped manually into the tank so that the molten solder sticks to the exposed metallic areas of the board. The molten solder is obtained in these tanks, by putting and heating the solder bars in the tank.
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