9 gm of a 75 solution in mek and 470 7 gm of mek after thorough mixing 132 gm of bisphenol af polysulfone 15 wt wt percent was added portionwise and was stirred mechanically until complete dissolution was achieved the resulting varnish was crystal clear amber colored liquid indicating complete dissolution of all components in the methyl ethyl ketone approximately one hour prior to use the above mentioned resin solution was catalyzed with 200 ppm of manganese octanoate 25 0 gm of a 0 006 solution in mek the resin solution was impregnated into a 106 style e glass and k glass reinforcing fabric using an impregnation treater tower the resulting prepreg was heat treated at 140 u00b0 c for approximately 4 minutes to remove the mek solvent and to 34 b stage 34 the resin the prepreg was cut and laminated into test specimens which were used for determining the dielectric constant moisture absorption coefficient of thermal expansion copper peel strength and interlaminate bond strength the results of these evaluations are summarized in tables 1 3 copper clad laminates upon which the copper peel test was conducted and circuit boards were prepared by superimposing several layers of the preptog between one or mere sheets of copper these structures were cured at approximately 250 u00b0 c to 325 u00b0 c under approximately 300 psi of pressure for approximately two hours parallel plate dielectric constant tests were conducted on the samples the results are set forth in table 1 thermal analysis tests were also conducted on samples to determine the glass transition temperature table 1__________________________________________________________________________composition dielectric in plane.