Hot air leveling and FPC
Hot air leveling was originally developed for rigid printed circuit board PCB lead-out technology, because this technology is simple and also used in FPC. Hot air leveling refers to the vertical plate in the system directly immersed in the molten tin bath; the excess solder is removed by hot air blowing. As the polyimide film is easy to absorb moisture, foam or even stripping in the cover layer will happen due to rapid heating caused by the absorption of moisture, so before the FPC hot air leveling, must be taken the dry and moisture management.
Is it hard to find problems of FPC?
When the FPC is newly plated, its appearance has no problem, but soon after some surface will have stains, dirt, and color and so on. Sometimes, the factory inspection still cannot find any, but the user will find the appearance problem. This is due to insufficient plating rafting and it slowly caused by chemical reactions on the surface after a period of time. In order to prevent this situation, you should not only fully drift, but also conduct a thorough drying. It is possible to confirm whether drifting is sufficient or not by the high temperature thermal aging test.
FPC can be widely used