Process Sequence of heat transfer in the vapour phase
1. The assembly is moved into the
vapour phase. It is either preheated by IR radiators or on the upper
boundary of the vapour phase.
2. The use of IR preheat improves the quality of the
solder joint and permits control of the temperature profiles.
3. The assembly descends into the vapour phase, where
it is heated up. With the patented Soft vapour phase (SVP) process, it
is possible to control the heat transfer to the assembly in a way that
a soft temperature rise is performed.
4. The vapour condenses on the assembly and transfers
its thermal energy. Since the vapour is chemically inert, it provides a
protective gas atmosphere with 0 ppm oxygen. Thus there is no need for
additional nitrogen.
5. The assembly can be heated up to a maximum
temperature that equals the temperature of the vapour only. No matter
how long the assembly stays in the vapour, the temperature of the
vapour cannot be exceeded. Overheating is physically impossible.
6. After leaving the vapour phase there is still
condensed fluid left on the board. Due to the inner heat of the
assembly, the liquid evaporates and a dry assembly leaves the machine.
