... ignore this point, so that result in lots of problems about exploding.In all of our products, there is an Air Regulator knob, the way ... ,humidity, light air flow in room, thickness of PCB, distribution of PCB cooper, etc. There is not a kind of curve which can be used ... the quantity of heat in a same unit, so the higher the temperature of chip. This is a very simple principle, all of welding equipments ...