Polyimide films with superior alkali etching workability and superior stamping workability

Abstract

A polyimide film according to the present invention satisfies Condition (1) in which a tear propagation resistance variation C H is not more than 1.0 g, and/or Condition (2) in which a swelling coefficient C R after being dipped in an alkaline solution is not more than 20.0. By satisfying these conditions, workability of the polyimide film can be improved and working defects can be effectively prevented, thereby improving productivity of each step.

1 - 8 . (canceled)  
   
   
       9 . A producing process of a flexible printed circuit board, comprising the step of exposing to an alkaline solution a polyimide film with a swelling coefficient of not more than 20.0 after being dipped in an alkaline solution, and not less than 25 mol % of paraphenylene diamine and not less than 25 mol % of 4,4-diaminodiphenylether, both as diamine components, with respect to a total diamine component, said polyimide film comprising a repeating unit of formula (1) below in its molecules  
     
       
         
         
             
             
         
       
     
     where R is  
     
       
         
         
             
             
         
       
     
     and/or  
     
       
         
         
             
             
         
       
     
     and where n of the group R is an integer of 1 to 3, X and Y are independently a hydrogen, a halogen, a carboxyl group, a lower alkyl group with no greater than 6 carbon atoms, or a lower alkoxy group with no greater than 6 carbon atoms, and A is —O—, —S—, —CO—, —SO 2 —, or —CH 2 —, and where R 1  is selected from the group consisting of  
     
       
         
         
             
             
         
       
     
     where R 2  in formula (3) is a divalent organic group that is selected from the group consisting of  
     
       
         
         
             
             
         
       
       where R 3  is independently —CH 3 , —Cl, —Br, —F, or CH 3 O.  
     
   
   
       10 . A producing process as set forth in  claim 9 , wherein said polyimide film is such that a raised portion thereof is not more than 5 mm in height when a 100 mm×100 mm square piece of said polyimide film is dipped in an alkaline solution for 5 minutes at 40° C. and then dried at 150° C. for 15 min, where the alkaline solution has been prepared by dissolving KOH in a mixed solvent of an 8:2 weight ratio of ethanol and distilled water to the final concentration of 1 mole/liter.