Fabricating microfluidics directly onto a printed circuit board (PCB) is a promising method to produce integrated systems. We applied stereolithography (SLA) to 3D print microfluidic components directly onto PCBs. Current SLA resins suffer from significant thermal expansion, which leads to adhesion issues during temperature cycling. In this paper, we report the development of photocurable composites with a low coefficient of thermal expansion (low-CTE composites) to address this bonding issue by minimizing the interfacial thermal stress. The resulting low-CTE resin-silica composites robustly bond to PCBs and can be used for fabricating PCB-based microfluidics in chemical engineering or thermal management (e.g., chemical reaction, 3D packaging, or heat removal devices).