PCB Blogger-China PCB Factory,HOYOGO

In PCBA factory , flux is an indispensable auxiliary material in the welding process. The quality of the welding effect is not only related to the quality of the welding technology, components and printed circuit boards, but also the selection of flux is very important. Do you know how to choose flux?   1. Performance requirements for flux 1) The flux need to have the characteristics of removing surface oxides, preventing re-oxidation and reducing surface tension, which is the basic performance that the flux must have.     2)  The melting point should be lower than the solder.   Before the solder melts, the flux must melt first to fully exert its fluxing effect.     3) The wetting and diffusion speed of flux is faster than that of molten solder.     4 ) The viscosity and density of flux are smaller than that of solder. A high viscosity will make wetting and diffusion difficult, and a high density will not cover the solder surface.   ...

     In the PCBA processing process, welding is a very important process.   If there is a slight negligence in the operation and the relevant process regulations are not implemented, it will cause poor welding. The more common welding defects are: cold joint, false welding, continuous welding, cold welding, less welding, etc. So what is false welding? Why does false welding occur?       False welding means that during the PCBA welding process, although the manual visual inspection has already shown the effect of successful welding, sometimes the leads and solder joints can be separated by  gently poking with your fingers.   That is, it seems that the welding is successful, but in fact the welding fails. Because the false welding phenomenon is difficult to distinguish with the naked eye, it is generally found during AOI inspection.     The main reasons for false welding are welding iron tips, flux, component pins and welding tin qual...