Polyimide film

Abstract

Disclosed herein is a polyimide film having inorganic particles. The polyimide film is 12-250 μm in thickness. The polyimide film includes about 50-90 weight parts of polyimide and about 10-50 weight parts of the inorganic particles. The particle size of each of the inorganic particles is about 0.1 μm to about 5 μm. The polyimide film is characterized in that the thermal expansion coefficient is equal to or less than 30 ppm/° C. in any direction, the difference between two thermal expansion coefficients in two mutually perpendicular directions on the film surface is less than 10 ppm/° C., and the Young's modulus of the polyimide film is greater than 4 GPa in any direction. The dimensional stability of the polyimide film measured by the standard of IPC-TM-650 is less than 0.10% in any direction. A method for manufacturing the polyimide film is disclosed as well.

What is claimed is: 
     
         1 . A polyimide film having inorganic particles prepared by a process including the steps of: (a) mixing a plurality of inorganic particles with a solvent, and stirring the inorganic particles and the solvent to form a suspending liquid, wherein each of the inorganic particles has a particle size of about 0.1 μm to about 5 μm; (b) mixing and string a diamine monomer and a tetracarboxylic dianhydride monomer with the suspending liquid to polymerize the diamine monomer and the tetracarboxylic dianhydride monomer, and thus forming a polyamic acid mixture containing the inorganic particles; (c) coating the polyamic acid mixture on a substrate and then performing a drying process to form a dried layer of polyamic acid mixture on the substrate; (d) separating the dried layer of polyamic acid mixture from the substrate to form a polyamic acid mixture film; and (e) uniaxially stretching and heating the polyamic acid mixture film simultaneously to convert the polyamic acid mixture film into the polyimide film;
 wherein the polyimide film is about 12 μm to about 250 μm in thickness, a difference between two thermal expansion coefficients in any two mutually perpendicular directions on the film surface is less than 10 ppm/° C., the two thermal expansion coefficients are equal to or less than 30 ppm/° C., the Young's modulus of the polyimide film is greater than about 4 GPa in any direction, and the dimensional stability of the polyimide film measured by the standard of IPC-TM-650 is less than 0.10% in any direction. 
 
     
     
         2 . A polyimide film having inorganic particles and with a thickness of about 12 μm to about 250 μm, the polyimide film comprising:
 about 50 to about 90 weight parts of the polyimide; and 
 about 10 to about 50 weight parts of inorganic particles, wherein each of the inorganic particles has a particle size of about 0.1 μm to about 5 μm; 
 wherein a difference between two thermal expansion coefficients in any two mutually perpendicular directions on the film surface is less than 10 ppm/° C., the two thermal expansion coefficients are equal to or less than 30 ppm/° C., the Young's modulus of the polyimide film is greater than about 4 GPa in any direction, and the dimensional stability of the polyimide film measured by the standard of IPC-TM-650 is less than 0.10% in any direction. 
 
     
     
         3 . The polyimide film of  claim 2 , wherein the particle size is about 0.5 μm to about 3 μm. 
     
     
         4 . The polyimide film of  claim 2 , wherein the inorganic particles are existed in a concentration of 25-38% by weight of the polyimide film.