Disclosed is a urethane modified
polyimide based
flame retardant resin composition having excellent
solubility in non-nitrogenous solvents,
varnish stability, low temperature
drying / curing, low warpage, flexibility, printability, and
flame resistance, and also having excellent
heat resistance,
chemical resistance, electrical properties, and
operability, and is low-cost. The urethane modified
polyimide based
flame retardant resin composition is characterized by containing: (A) a urethane modified
polyimide based resin having urethane bonds and generated having as essential components (a) trivalent and / or 4-valent polycarboxylic acid derivatives having an
acid anhydride group, (b)
diol compounds, and (c) aliphatic
polyamine residue derivatives and / or aromatic
polyamine residue derivatives; (B) an
epoxy resin having two or more
epoxy groups per molecule; (C) an organic or
inorganic filler; and, (D) a non-
halogen-based flame retardant, wherein the non-
halogen-based flame retardant (D) contains two essential components (D-1 and D-2), wherein, in an
air atmosphere at 350 DEG C, the rate of weight reduction of one component (D-1) is greater than or equal to 50% and less than or equal to 90%, and that of the other component (D-2) is greater than or equal to 0% and less than or equal to 20%.