Fabrication of microchannels using polycarbonates as sacrificial materials

The use of polycarbonates as thermally decomposable, sacrificial materials for the formation of microchannels is presented. Pol, carbonates decompose in the temperature range of 200-300 degreesC. Two polycarbonates, polyethylene carbonate and polypropylene carbonate, have been used to fabricate microchannels in three different types of encapsulants: an inorganic glass (silicon dioxide), a thermoplastic polymer (Avatrel dielectric polymer) and a thermoset polymer (bisbenzoycyclobutene Cyclotene 3022-57). This paper presents the details of the fabrication process, a thermogravimetric analysis of the sacrificial materials, and the kinetic parameters for the decomposition process. The presence of oxygen or water was found to impact on the decomposition of the sacrificial material. This paper demonstrates the feasibility of forming buried air-cavities in a variety of encapsulants at a modest temperature, thus enabling the use of a wide range of dielectric materials with different thermal stabilities and properties.