The recent developments in microsystems technology lead to an increased complexity of the components while the component mass decreases at the same time. For an economic production of thermoplastic micro parts a reproducible quality is one of the key aspects. Therefore, the injection moulding is one of the most common production technologies. The material and process oriented plasticizing of the required amount of plastic material is still challenging. Due to the concept of standard injection moulding machines the plasticizing screw with a non-return valve is used as the injection plunger. Therefore, this principle can only realize injection volumes which arise directly from the screw diameter D and the injection stroke. For a uniform dosing, a controlled closing of the non-return valve and for a reproducible injection the stroke should be within 1-3 D. Simultaneously, the screw core must absorb the required torque while the feeding of the granules is to ensure by a sufficient flight depth. Even the smallest diameters of 14 mm and minimum injection strokes result in shot volumes which account for multiple of the component volume of common micro parts. The paper presents a new plasticizing concept developed by the Institute of Plastics Processing, Aachen, Germany. The concept is characterized by the position of the screw flights, which are attached to the inside of the plasticizing cylinder. The injection piston is mounted coaxially within the cylinder. The so-called ‘inverted plastication’ is based on the kinematic reversal of the screw flights’ arrangement. Hence the injection piston does not have to feature neither a special feed section nor screw flights it is exposed to lower mechanical stresses. It therefore features a smaller diameter than common plasticizing screws. Thus, the entire plasticizing unit can be adapted to the volume of micro parts. Currently, a test rig is built which allows a systematical analysis of the different influencing parameters.