Method for sticking an insulating film to a lead frame

Abstract

A method for punching an insulating film is composed of using plural divided punches having a clearance between each two of the divided punches. The clearance absorbs thermal expansion of the divided punches caused by receiving a heat from a heater. A punched insulating film is stuck to a lead frame by being pressed between the divided punches and the heater.

What is claimed is:  
     
       1. A method for sticking an insulating film to a lead frame comprising the steps of: 
       providing a punch for punching a thermally adhesive insulating film, said punch having a clearance within it for absorbing thermal expansion thereof;  
       punching said thermally adhesive insulating film to provide a punched film by said punch;  
       heating a lead frame placed on a heater by said heater; and  
       pressing said punched film to said lead frame on said heater by said punch, thereby sticking said punched film to said lead frame  
       wherein thermal expansion of said punch occupying as a result of carrying out the step of heating said lead frame is absorbed by said clearance of said punch.  
     
     
       2. A method for sticking an insulating film to a lead frame according to claim  1 , wherein: 
       said pressing step is carried out in a state where said heater is mounted on a heater fixing plate on an air cylinder.  
     
     
       3. A method for sticking an insulating film to a lead frame comprising the steps of: 
       
         providing a punch for punching thermally adhesive insulating film;  
       
       
         punching said thermally adhesive insulating film to provide a punched film by said punch;  
       
       
         providing a lead frame placed between a heater, for heating said lead frame, and said punch;  
       
       
         providing a means for maintaining a constant pressing force produced between said punched film and said lead frame, said means mounting said heater and functioning to move said heater up and down;  
       
       
         moving said heater up to a predetermined position level in accordance with the function of said means to contact and heat said lead frame; and  
       
       
         fixing said punched film on said heated lead frame in accordance with said pressing force.  
       
     
     
       4. The method as defined in claim  3 , wherein the step of moving said heater up to said predetermined position level is carried out in a state where said heater is mounted on a heater fixing plate on an air cylinder which is said means for maintaining a constant pressing force.