The detector modules of the Silicon Tracking System of the Compressed Baryonic Matter experiment at FAIR comprise double-sided silicon microstrip sensors with a size of up to 124 mm x 62 mm. Due to tight material budget constraints, the sensors are connected to the read-out electronics by long flexible microcables. As manual assembly of the modules is time-consuming and difficult, a fully customized in-house bonder machine has been developed which allows for a highly automated detector module assembly. We present the requirements and the setup of the bonder machine together with the achieved alignment accuracy and first assemblies.