Matte finish polymide films and methods relating thereto

Abstract

The present disclosure is directed to a base film having a thickness from 8 to 152 microns, a 60 degree gloss value from 2 to 35, an optical density greater than or equal to 2 and a dielectric strength greater than 1400 V/mil. The base film comprises a chemically converted (partially or wholly aromatic) polyimide in an amount from 71 to 96 weight percent of the base film. The base film further comprises a pigment and a matting agent. The matting agent is present in an amount from 1.6 to 10 weight percent of the base film, has a median particle size from 1.3 to 10 microns, and has a density from 2 to 4.5 g/cc. The pigment is present in an amount from 2 to 9 weight percent of the base film. The present disclosure is also directed to coverlay films comprising the base film in combination with an adhesive layer.

What is claimed is: 
     
         1 . A base film comprising:
 A) a chemically converted polyimide in an amount from 71 to 96 weight percent of the base film, the chemically converted polyimide being derived from:
 a. at least 50 mole percent of an aromatic dianhydride, based upon a total dianhydride content of the polyimide, and 
 b. at least 50 mole percent of an aromatic diamine based upon a total diamine content of the polyimide; 
   B) a low conductivity carbon black present in an amount from 2 to 9 weight percent of the base film; and   C) a matting agent mixture that:
 a. is present in an amount from 1.6 to 10 weight percent of the base film to produce a 60 degree gloss value of from 2 to 35, 
 b. has a median particle size from 1.3 to 10 microns, 
 c. has a density from 2 to 4.5 g/cc, and 
 d. includes silica and alumina, silica and barium sulfate, or alumina and barium sulfate. 
   
     
     
         2 . A base film in accordance with  claim 1  wherein:
 a. the aromatic dianhydride is selected from the group consisting of:
 pyromellitic dianhydride, 
 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 
 3,3′,4,4′-benzophenone tetracarboxylic dianhydride; 
 4,4′-oxydiphthalic anhydride, 
 3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride, 
 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, 
 Bisphenol A dianhydride, and 
 mixtures thereof; and 
 
 b. the aromatic diamine is selected from the group consisting of:
 3,4′-oxydianiline, 
 1,3-bis-(4-aminophenoxy) benzene, 
 4,4′-oxydianiline, 
 1,4-diaminobenzene, 
 1,3-diaminobenzene, 
 2,2′-bis(trifluoromethyl) benzidene, 
 4,4′-diaminobiphenyl, 
 4,4′-diaminodiphenyl sulfide, 
 9,9′-bis(4-amino)fluorine and 
 mixtures thereof. 
 
 
     
     
         3 . The base film in accordance with  claim 1  wherein the chemically converted polyimide is derived from pyromellitic dianhydride and 4,4′-oxydianiline. 
     
     
         4 . A multilayer film comprising the base film of  claim 1  and an adhesive layer. 
     
     
         5 . A multilayer film in accordance with  claim 4 , wherein the adhesive layer is an epoxy resin selected from the group consisting of: Bisphenol A epoxy resin, cresol novolac epoxy resin, phosphorus containing epoxy resin, and mixtures thereof. 
     
     
         6 . A multilayer film in accordance with  claim 4 , wherein the multilayer film is a coverlay film. 
     
     
         7 . The base film in accordance with  claim 1 , wherein the base film has a thickness from 8 to 152 microns. 
     
     
         8 . A chemically converted polyimide film having an optical density ≧ to 2 comprising:
 A) a chemically converted polyimide in an amount from 71 to 96 weight percent of the film, the chemically converted polyimide being derived from:
 a. at least 50 mole percent of an aromatic dianhydride, based upon a total dianhydride content of the polyimide, and 
 b. at least 50 mole percent of an aromatic diamine based upon a total diamine content of the polyimide; 
 
 B) a low conductivity carbon black present in an amount from 2 to 9 weight percent of the base film; and 
 C) a matting agent mixture that:
 a. is present in an amount from 1.6 to 10 weight percent of the film to produce a 60 degree gloss value of from 2 to 35, 
 b. has a median particle size from 1.3 to 10 microns, 
 c. has a density from 2 to 4.5 g/cc, and 
 
 d. includes silica and alumina, silica and barium sulfate, or alumina and barium sulfate. 
 
     
     
         9 . The chemically converted polyimide film in accordance with  claim 8  wherein the aromatic dianhydride is a pyromellitic dianhydride and the aromatic diamine is selected from the group consisting of:
 3,4′-oxydianiline, 
 1,3-bis-(4-aminophenoxy) benzene, 
 4,4′-oxydianiline, 
 1,4-diaminobenzene, 
 1,3-diaminobenzene, 
 2,2′-bis(trifluoromethyl) benzidene, 
 4,4′-diaminobiphenyl, 
 4,4′-diaminodiphenyl sulfide, 
 9,9′-bis(4-amino)fluorine and 
 mixtures thereof. 
 
     
     
         10 . A multilayer film comprising the chemically converted film of  claim 8  and an adhesive layer. 
     
     
         11 . A multilayer film in accordance with  claim 10 , wherein the adhesive layer is an epoxy resin selected from the group consisting of: Bisphenol A epoxy resin, cresol novolac epoxy resin, phosphorus containing epoxy resin, and mixtures thereof. 
     
     
         12 . A multilayer film in accordance with  claim 11 , wherein the multilayer film is a coverlay film. 
     
     
         13 . A chemically converted polyimide film comprising a film having:
 A) a thickness of about 8 to 152 microns,   B) an optical density 2,   C) surfaces with a 60 degree gloss value of from 2 to 35   D) 2 to 9 weight percent of a low conductivity carbon black   E) 1.6 to 10 weight percent of a matting agent mixture, the matting agents have a median particle size from 1.3 to 10 microns and a density from 2 to 4.5 g/cc, and the mixture includes silica and alumina, silica and barium sulfate, or alumina and barium sulfate, and   F) 71-96 polyimide by weight chemically derived from:
 a. at least 50 mole percent of an aromatic dianhydride, based upon a total dianhydride content of the polyimide, and 
 b. at least 50 mole percent of an aromatic diamine based upon a total diamine content of the polyimide; 
   
     
     
         14 . The chemically converted polyimide film in accordance with  claim 13  wherein the aromatic dianhydride is a pyromellitic dianhydride. 
     
     
         15 . A multilayer film comprising the chemically converted film of  claim 13  and an adhesive layer. 
     
     
         16 . A multilayer film in accordance with  claim 15 , wherein the adhesive layer is an epoxy resin selected from the group consisting of: Bisphenol A epoxy resin, cresol novolac epoxy resin, phosphorus containing epoxy resin, and mixtures thereof. 
     
     
         17 . The chemically converted polyimide film in accordance with claim having a dielectric strength greater than 1400 V/mil 
     
     
         18 . The chemically converted polyimide film in accordance with  claim 8 , having a dielectric strength greater than 1400 V/mil. 
     
     
         19 . The chemically converted polyimide film in accordance with  claim 13 , having a dielectric strength greater than 1400 V/mil. 
     
     
         20 . A chemically converted polyimide film comprising a film having:
 A) a thickness of about 8 to 152 microns,   B) an optical density 2,   C) 1.6 to 10 weight percent of a silica or alumina based matting agent mixture sufficient to provide major surfaces of the chemically converted polyimide with a 60 degree gloss value of from 2 to 35, and   D) a dielectric strength greater than 1400 V/mil