Recently, thermoplastic polymers have become popular materials for microfluidic chips due to their easy fabrication and low cost. A polymer based microfluidic device can be formed in various fabrication techniques such as laser machining, injection molding, and hot embossing. A new bonding process presented in this paper uses a 2.5% (w/w) polymethyl methacrylate (PMMA) solution as an adhesive layer to bond dissimilar polymers—PMMA to polycarbonate (PC)—to enclose the PMMA microfluidic channels with PC. This technique has been successfully demonstrated to bond PMMA microchip to PC film. This paper presents bonding strength using a shear strength test and a crack opening method in addition to the fluidic leakage inspection.