Liquid silicone rubber with modified adhesive properties enables multi-component thermoplast-silicone composites to be injection molded without requiring mechanical linkage. In most cases, the chemical structure of the in situ bonding agent is only capable of connecting to chemically compatible thermoplasts, such as PBT and PA. When dealing with PC, adhesion with these LSR types is only possible if previous surface modifications have been performed, i.e., plasma-, corona- or flame-treatments. Unfortunately, these intricate processes also come at a high cost, and the complexity of integration into a multi-component injection molding process is an evident disadvantage. Another possibility to achieve the adhesion of LSR on polycarbonate is by means of irradiating the thermoplastic surface with UVC light. The effect is very powerful as long as the irradiation dose is high enough. Using a common mercury vapor arc lamp and optimal conditions, irradiation periods under five seconds generate a strong bond with cohesive failure within the silicone rubber. In comparison to other studies in literature, which investigated the optimization of liquid coatings, the UVC irradiation doses required to activate the surface of PC to achieve bonding to LSR are much lower. In this study, the effects, correlations, and limits of the UVC light treatment applied to PC-LSR composites were evaluated using experimental designs. The VDI guideline 2019 was used to determine the adhesive strengths of the composites. It became clear that surface activation works for different polycarbonate and LSR types. The most important aspect is the amount of UVC irradiation needed on the thermoplastic surface. Surprisingly, the production conditions in injection molding play a minor role. The surface pre-treatment of polycarbonate with UVC light is, unlike other treatment processes, stable long-term and resistant against various secondary treatment processes, such as sterilization, heat, or storage in media.