Study on bisbenzocyclobutene bonding for the development of a Si-based miniaturized reformer of fuel cell systems

This paper reports the results of a systematic study of bisbenzocyclobutene (BCB) bonding for a Si-based miniaturized reformer system. The micro reformer system, which included microchannels with a depth and a width of 250 νm and 600 νm, respectively, was fabricated using conventional semiconductor processing and BCB bonding. The structural, thermo-mechanical and chemical stability of Pyrex to Si wafer bonding using BCB as an adhesive was examined at temperatures up to 350 °C. The BCB interfaces at the Pyrex to Si wafer bonding pairs were mechanically stable to withstand the typical pressure and temperature conditions of the reforming process (1 atm and 300 °C) with little outgassing during reforming at 1 atm and 300 °C. The thermo-mechanical and chemical stability during wafer bonding and during reforming was examined using an optical inspection, and pressure pop-up test, FTIR test and gas chromatograph (GC) test were performed. The results showed that Pyrex to Si wafer bonding using BCB is suitable for a miniaturized reformer in fuel systems.