Solder Pastes for Microwave Application

A selective and also simultaneous reflow soldering process is possible in principle by using of electromagnetic fields, if the field energy is penetrating the processed assembly and is able to launch into specific material regions, depending on material properties (Nowottnick, 2005). The application of electromagnetic radiation in the microwave range enables the treatments of products with different sizes and shapes, also with an open inline system with a high throughput. But common solder pastes are demanding a lot of time and a high power density for heating with microwave. By adding a defined amount of a special well launching material to the solder paste, the so called suszeptor, it is possible to increase the efficiency of microwave heating considerably. Such suszeptors must have adequate polar or dielectric properties and have to be mixed to the soldering flux as a solid or liquid. By means of this mixture is it possible to fasten the heating of solder paste in comparison with the remaining assembly, which is necessary for minimizing of used microwave energy