Development of a Duothermal Soldering Process

For joining electric or electronic components and a printed circuit board, mass soldering methods are mostly applied due to their high productivity. In few cases selective soldering is required concerning economical or technical issues. However, also established selective soldering methods are incapable of reliably soldering temperature sensitive components. The substrates or the elements often cannot withstand the applied process temperatures of these methods. A new selective soldering process, the Duothermal Soldering, was developed which reduces heat input to the joint by employing low process temperature and precisely dispensing solder. This process is based on separating the application of heat to liquefy the solder and to heat the elements to be joined. For the purpose of evaluation, a prototype has been implemented and tested on flexible printed circuits and flexible flat cables.