Patent ID: 6956098

Claim:
A substrate comprising: a polyimide layer having a thickness in the range of from 2, 3, 4, 5, 7, 10, 12, 15, 17, or 20 microns to about 50, 100, 200, 250 or 500 microns, said polyimide layer comprising a polyimide base polymer, said polyimide base polymer being synthesized by contacting together in one or more steps a precursor composition comprising a diamine and a dianhydride, at least 70, 75, 80, 85, 90, 92, 94, 95, 96, 97, 98, 99 or 100 mole percent of the diamine being an aromatic crankshaft diamine and an aromatic collinear diamine, the aromatic crankshaft diamine to aromatic collinear diamine being in a mole ratio of about 60-95:5-40; at least 70, 75, 80, 85, 90, 92, 94, 95, 96, 97, 98, 99 or 100 mole percent of the dianhydride being an aromatic crankshaft dianhydride and an aromatic collinear dianhydride, the aromatic crankshaft dianhydride and the aromatic collinear dianhydride being in a mole ratio of about 5-35:65-95, the diamine and dianhydride crankshaft components being either a non-rigid type crankshaft monomer or a rigid type crankshaft monomer whereby the mole ratio of non-rigid crankshaft monomer to rigid crankshaft monomer is A:B, where A is a range from 50, 55, 60, 65, 70, 75, or 80, to about 80, 85, 90, 92, 94, 95, 96, 97, 98, 99 or 100, and B is a range from 0, 1, 2, 3, 4, 5, 6, 8, 10, 15, or 20 to about 20, 25, 30, 25, 40, 45 or 50; the precursor composition being cured to a tensile modulus greater than 700, 725, 750, 775 or 800 kpsi (at 20° C.) to provide the polyimide base polymer having the following properties: a. a transmission rate of water vapor greater than about 0.3, 0.35, 04, 0.45, 0.5, 0.55, 0.6, 0.65, or 0.7 gram-mm/(m 2 -day), and b. a coefficient of linear thermal expansion of from 5-25 ppm/° C. measured between 50° C. and 250° C.