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 mum and 600 mum, 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 deg 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 deg C) with little outgassing during reforming at 1 atm and 300 deg 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.