Circuit board welding skills 1, selective soldering process comprises: fluxing, preheating the circuit board, dip soldering and drag soldering. Flux coating process in selective soldering flux coating process plays an important role. At the end of the welding heat and welding flux should be sufficient to prevent the activity of bridging the generation and prevent oxidation circuit board. Fluxing by the X / Y robot carrying the circuit board above the spray nozzle by flux, solder flux to the pcb board position.
2, microwave peak reflow soldering process after the election, the most important is the accurate spray flux, micro jet never soiled pad outside the area. Micro-point minimum flux spray dot pattern diameter greater than 2mm, so spray deposition flux in the positional accuracy of the board of ± 0.5mm, in order to ensure that the flux is always covered in the welded parts of the above.
3, can be compared with the wave soldering process to understand the characteristics of selective soldering, the most obvious difference between the two lies in the lower part of wave soldering circuit boards completely immersed in liquid solder, soldering and selective, only some specific area in contact with the solder wave. Since the circuit board itself is a poor heat transfer medium, so it does not heat melting welding adjacent components and circuit board area of the solder joints.
Before welding must be pre-applied flux, as compared to wave soldering, flux coating only the lower portion of the circuit board to be welded, rather than the entire pcb board. Further selective soldering is only suitable for welding cartridge element, selective soldering is a new approach, a thorough understanding of selective soldering processes and equipment are necessary for successful welding.