Abstract: A resin composition containing (A) a polyimide having acidic functional groups and (B) a compound having functional groups that react with the acidic functional groups, where (a) a solution rate in 3 mass % aqueous sodium hydroxide at 45° C. is 0.95 or more after a heat history of 90° C. for 10 minutes with the solution rate before the heat history assumed to be 1, (b) the solution rate in 3 mass % aqueous sodium hydroxide at 45° C. ranges from 0.001 ?m/sec to 0.02 ?m/sec after the heat history of 180° C. for 60 minutes, (c) a bleed-out amount is 50 mg/m2 or less in storing at 40° C. for 2 weeks after the heat history of 180° C. for 60 minutes, and (d) a thermogravimetric decrease at 260° C. is 2.0% or less in measuring on a temperature rising condition of 10° C./min from 40° C. by thermogravimetric analysis (TG).

Abstract: A resin composition containing (A) a polyimide having acidic functional groups and (B) a compound having functional groups that react with the acidic functional groups, where (a) a solution rate in 3 mass % aqueous sodium hydroxide at 45° C. is 0.95 or more after a heat history of 90° C. for 10 minutes with the solution rate before the heat history assumed to be 1, (b) the solution rate in 3 mass % aqueous sodium hydroxide at 45° C. ranges from 0.001 ?m/sec to 0.02 ?m/sec after the heat history of 180° C. for 60 minutes, (c) a bleed-out amount is 50 mg/m2 or less in storing at 40° C. for 2 weeks after the heat history of 180° C. for 60 minutes, and (d) a thermogravimetric decrease at 260° C. is 2.0% or less in measuring on a temperature rising condition of 10° C./min from 40° C. by thermogravimetric analysis (TG).

Abstract: A novel flexible printed circuit substrate can be processed into a flexible printed circuit board having a high-accuracy connecting part which does not cause a connection failure when it is connected to a connector even if a pitch between two adjacent terminals is further reduced. The flexible printed circuit substrate has dummy patterns which are formed, simultaneously with the terminals, on the sides of the connecting part, in a shape corresponding to the outline of both sides of connecting part which are used for positioning the terminals when the connecting part is attached to the connector. The dummy patterns are used as masks when a base film is subjected to a laser process.

Abstract: A novel flexible printed circuit substrate can be processed into a flexible printed circuit board having a high-accuracy connecting part which does not cause a connection failure when it is connected to a connector even if a pitch between two adjacent terminals is further reduced. The flexible printed circuit substrate has dummy patterns which are formed, simultaneously with the terminals, on the sides of the connecting part, in a shape corresponding to the outline of both sides of connecting part which are used for positioning the terminals when the connecting part is attached to the connector. The dummy patterns are used as masks when a base film is subjected to a laser process.