HYDROLYSIS AND BLISTERING OF CYANATE ESTER NETWORKS

The hydrolysis of a cyanate ester network made from the monomer 2,2'-b is (4-cyanatophenyl) isopropylidene (bisphenol A dicyanate homopolymer ) was studied. Hydrolysis reactions were performed isothermally at tem peratures from 150 to 180 degrees C under conditions of excess water. The kinetics of the reaction were characterized by the decrease in T-g as measured by differential scanning calorimetry. The rate of change of T-g was found to be adequately described as first order in T-g, whi ch is an indirect measure of the concentration of crosslink junctions. The activation energy of the reaction was found to be 115 kJ/mol. In addition, moisture-conditioned, glass-reinforced laminate samples were heated and the time to delamination or blistering was recorded as a f unction of temperature. The blister time at solder temperatures (T = 2 20-260 degrees C) was modeled using the above kinetic results. Heat tr ansfer to the laminate was considered and the criteria used for bliste r time was the time at T = T-g of the sample. At lower temperatures (T < 220 degrees C), loss of water from the laminate is sufficiently fas t to prevent blistering. (C) 1997 John Wiley & Sons, Inc.