TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The monomers further include a second aromatic diamine selected from p-phenylenediamine (PDA), 4,4'-oxydianiline (4,4'-ODA), diaminodiphenyl ether (3,4-DAPE), diaminodiphenyl sulfone (DDS) and 4,4'-diamino-triphenyamine. The variation of the linear coefficient of thermal expansion at temperature of 100-500 degrees C is less than or equal to 11 ppm/ degrees C. The average linear coefficient of thermal expansion is 0.1-4.5 ppm/ degrees C at temperature of 50-500 degrees C. The monomers further include a second aromatic diamine, where a molar ratio of the first aromatic diamine is greater than or equal to 15 mole% based on a total amount of diamines, and the second aromatic diamine is less than or equal to 85 mol % based on the total amount of diamines. The second aromatic diamine that is selected from p-phenylenediamine, and 4,4'-oxydianiline. The aromatic dianhydride is selected from 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 2,2'-bis-(3,4-dicarboxyphenyl)hexafluoropropane FDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfone, 5(2,5-dioxotetrahydrol)-3-methyl-3-cyclohexane-1,2-dicarboxylic anhydride, ethylene glycol bis(anhydro-trimellitate), and 2,3,3',4'-biphenyl tetracarboxylic anhydride. The conductive layer is a metal layer including Cu, Al, Au, Zn, Ga, In, Sn, Ag, Pd, Ni, Pt, Cr, Mo, W, and its alloy. The catalyst is selected from heterocyclic tertiary amines, aliphatic tertiary amines, and aromatic tertiary amines. The dehydrant is selected from aliphatic acid anhydrides and aromatic acid anhydrides.    TECHNOLOGY FOCUS - POLYMERS - Preferred Film: The aromatic polyimide film further comprises a second aromatic diamine selected from PDA, where a molar ratio of the first aromatic diamine:PDA is 99-15:1-85; 4,4'-ODA, where a molar ratio of the first aromatic diamine:4,4'-ODA is 99-90:1-10; and a combination of PDA and 4,4'-ODA, where a molar ratio of the first aromatic diamine:PDA:4,4'-ODA is 98-15:1-60:1-25. The aromatic polyimide film has a size variation that is less than 0.45% in absolute value at temperature of 25-500 degrees C. Preferred Method: The method further involves adding a dehydrant and a catalyst into the polyamic acid solution before coating a layer of the polyamic acid solution on a support; and heating the polyamic acid solution at 60-100 degrees C before baking the coated layer, where the baking temperature is 150-450 degrees C. EXAMPLE - A 32.19 g 6-amino-2-(p-aminophenyl)benzoxazole (PBOA), 3.86 g PDA, and 300 g DMAC were incorporated in flask, and completely dissolved by agitation at greater than or equal to 40 degrees C. Then, 38.95 g PMDA was added. The reaction mixture was continuously agitated for 20 hours at 25 degrees C to form a polyamic acid (PAA) solution with a viscosity of 140000 cps. The PAA solution was coated onto a glass plate support, and then baked in a furnace in a stepwise manner at 80 degrees C for 30 minutes to remove the solvent, and then at 170-420 degrees C for 4 hours to form a polybenzoxzole imide polyimide film.