![]() It also has some cost related benefits like reduced electricity consumption, reduced wear ot of carriers and no need for nitrogen. LMPA-Q needs less temperature and reduces oxydation. A new market tendency and the considered by some as the future of soldering is the use of a low melting point alloy like e.g. ![]() Because of the fact that lead-free soldering alloys need high working temperatures and tend to oxydise quite strongly, a lot of wave soldering processes are done in a nitrogen atmosphere. This wave is more sensitive to the correct setting and bridging. A wave former that is gaining popularity is the Wörthmann-wave that combines the function of the chip wave and the main wave in one wave. This will avoid the PCB being dragged through the reaction products of the soldering. The laminar main wave flows to the front but the adjustable back plate is positioned like this that the board will push the wave into a back flow. ![]() ![]() The chip wave jets solder in the direction of the PCB movement and allows to solder the back side of SMD components that are shielded of wave contact in the laminar wave by the body of the component itself is. A traditional setup is a chip wave combined with a laminar main wave. The liquid alloy is pumped through channels up into a wave former. This soldering temperature depends on the used soldering alloy. A bath filled with a soldering alloy is heated up to soldering temperature. In a third step the PCB board is passed over a solder wave. This gives a better chance that the liquid solder will reach the top of the through hole. A good preheating limits the temperature difference between PCB board and liquid solder and hence reduces the cool down of the liquid solder when going up the through hole. This is a typical problem when using Sn(Ag)Cu alloys. Thermally heavy boards and components can draw away so much heat from the liquid solder that it is cooled down to the solidification point where it freezes before it gets to the top. Because of the temperature difference between the PCB board and the liquid solder, the liquid solder will be cooled down when going up the through hole. The third function of the preheating is to promote through hole wetting of the solder. This can be important for some SMD components and PCB materials. The second function of the preheating is to limit the thermal shock when the PCB contacts with the liquid solder of the solder wave. Water based fluxes in general need more preheating to evaporate than alcohol based fluxes. The solvent of the flux needs to be evaporated as it loses its function once its has been applied and it can lead to soldering defects like briding and solder balling when it contacts the solder wave in a liquid state. The purpose of the flux is to deoxydize the solderable surfaces of the PCB and components and allow the liquid soldering alloy to make an intermetallic connection with those surfaces resulting in a solder joint. The liquid flux is applied from the bottomside of the PCB on the surface and in the trough holes. The PCBs can be mounted in a frame to avoid adjusting the conveyor width for every different PCB.įluxing is usually done by means of a spray fluxer but also foam fluxing and jet fluxing are possible. A conveyor transports the PCBs through the machine. The wave soldering process comprises three main steps : Fluxing, preheating and soldering. The process is typically used for through hole components but can also be used for soldering of some SMD (Suface Mount Device) components that are glued with an SMT (Surface Mount Technology) adhesive to the bottom side of the PCB before passing through the wave soldering process. Wave soldering is a bulk soldering process used in electronics manufacturing to connect electronic components to a PCB board.
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