Abstract: A polyimide film that exhibits improved peel strength when clad with a metal layer is prepared by reacting a polyamic acid polymer and an esterified polyamic acid oligomer. The esterified oligomer has from two to twenty repeating units and at least two crosslinkable groups selected from the group consisting of carbonyl, cyano, hydroxy, alkyne, maleimide, norbornene and sulfonyl groups. The polyamic acid is dissolved in a solvent to form a polyamic acid solution, which has a minimum gel-film forming temperature, or a minimum green film forming temperature, associated therewith. The esterified polyamic acid oligomer has an imidization temperature, which is higher than the minimum gel-film forming temperature, or the minimum green film forming temperature, of the polyamic acid solution.

Abstract: A polyimide film that exhibits improved peel strength when clad with a metal layer is prepared by reacting a polyamic acid polymer and an esterified polyamic acid oligomer. The esterified oligomer has from two to twenty repeating units and at least two crosslinkable groups selected from the group consisting of carbonyl, cyano, hydroxy, alkyne, maleimide, norbornene and sulfonyl groups. The polyamic acid is dissolved in a solvent to form a polyamic acid solution, which has a minimum gel-film forming temperature, or a minimum green film forming temperature, associated therewith. The esterified polyamic acid oligomer has an imidization temperature, which is higher than the minimum gel-film forming temperature, or the minimum green film forming temperature, of the polyamic acid solution.