For about 30 years blister cards are a successful form of packaging for solid pharmaceuticals. Nevertheless there are still some important problems to solve. E.g. no fixed rules are set which help the processor to adjust the thermoforming process. The same applies to the sealing process. What is the influence of higher sealing plate temperatures besides a better cohesion between bottom and sealing foil? How does the sealing force influence the process? Does the relation of the layer thicknesses stay constant while a multilayer film is thermoformed? These and more questions were examined within the scope of a research project, financially supported from the German Federal Ministry of Economics and Technology and from the Arbeitsgemeinschaft industrieller Forschungsvereinigungen "Otto von Guericke" e.V. (AiF, Magdeburg, Germany) by the order of a research society for pharmaceuticals (Forschungsvereinigung der Arzneimittelhersteller, FAH, Bonn, Germany). The research project has been carried out at the Institute for Plastics Processing of Rheinisch-Westfalische Technische Hochschule (Aachen, Germany).