Demand on soldering heat

The heat requirement of a solder joint is that energy, which is required to bring the joint to a temperature sufficiently high so that the surfaces of the parts to be joined can safely be wetted by the solder. If this condition is met, the thermal requirement to form an acceptable solder joint is fulfilled. The amount of heat required is dependent on the mass of the printed circuit board, as well as that of the components. The greater the heat capacity of the solder joint, the higher is also the heat requirement.