Preparation and characterization of printable solder resist inks based on hyperbranched polyester

Two novel solder resist inks containing hyperbranched epoxy resin (HBPE) for thermal curing and hyperbranchai epoxy acrylate resin (HBPEA) for UV-curing were introduced in this work. Different generations of HBPF, and HBPFA were synthesized and their chemical structures were determined by FT-IR. Both curing reactions were monitored under differential scanning calorimetry (DSC) and photo-DSC. For HBPE, the curing temperature of 7th generation was only 91 degrees C and for HBPEA, the curing duration of 7th generation was under 10 s. The thermal stabilities of cured resins were much more stable than linear resin, as the decomposition temperatures of HBPE and HBPEA were both over 400 degrees C. The ink containing HBPE or HBPEA jetted by piezoelectric printer showed excellent accuracy and consistency of linewidth and the morphologies of cured pattern were observed through a stereo microscope. Other performances of solder masks were tested under China Printed Circuit Association (CPCA) standard (CPCA/JPCA 4306-2011), which satisfy all requirements of printed circuit board soldering procedure. (C) 2011 Wiley Periodicals, Inc.