Control a Joule-Heating Embedded Layer within a Printed Circuit Board

For a reflow soldering process the most energy consumption is used to heat up the machine itself. If it would be possible to heat up only the solder pins to the required temperature the energy reduction will be significant. The idea behind such a process is to use a conductive heating material layer inside the printed circuit board (PCB). To generate the joule heating, it is necessary to have an electric current flow inside the heating material. This flow must be controlled, because the heating layer is a carbon-based material and can change its resistance as a function of the temperature. In this paper an experimental setup will be described, to realize a control circuit for the heating layer. First only to compensate the resistance change based on the temperature. Second a control circuit to adjust the current flow for different structures or even variable connections for each product.