Self-Heating Printed Circuit Board - A Challenge to Contact and Control for a Reflow Soldering Process

For a reflow soldering process, most of the energy consumption is used to heat up the machine itself. If it would be possible to heat up only the solder and pins to the required soldering 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 through the heating material. The parameters for soldering in a reflow oven are known, but the heating from inside a PCB requires to define new parameters. This paper will describe basic experiments to achieve the necessary process and material parameters like required resistance of the heating layer to obtain a controllable reflow profile for the soldering material. The experiments performed also give boundary conditions for the resulting machine to use this soldering process automatically in a large-scale PCB production environment.