Barbituric acid-modified bismaleimide with diamine and polyisocyanate-modified epoxy resin

A process for manufacturing resins for use in a high glass transition temperature printed circuit board comprising:

• dissolving bismaleimide in a cosolvent of butyrolactone/methyl ethyl ketone wherein the weight of the cosolvent is 0.7 to 0.9 times that of the bismaleimide and the ratio by weight of butyrolactone/methyl ethyl ketone is from 5:1 to 3:1, and then adding a barbituric acid or its derivative whereby said bismaleimide undergoes reaction with said barbituric acid, the reaction of said bismaleimide with said barbituric acid being carried out at a temperature between 100.degree. and 130.degree. C. for about 0.5 to 1 hour to form a first product;
• dissolving an epoxy resin modified with a secondary diamine and polyisocyanate into 0.75 to 0.95 times by weight of a cosolvent of butyrolactone-methyl ethyl ketone having a ratio by weight of butyrolactone/methyl ethyl ketone of 0.25/1 to 0.35/1 at a temperature between 100.degree. to 150.degree. C. and then cooling to about 50.degree. to 85.degree. C., adding a curing agent dissolved in a solvent to form a first solution, adding said first solution into said first product and then stirring for 0.5 to 1.5 hour at a temperature of about 70.degree. to 130.degree. C. to produce the resins.