FLAME PROOFING COVER SHEET FOR FLEXIBLE PRINTED CIRCUIT BOARD

摘要

PURPOSE: To obtain a frame-proof cover sheet having a good frame proof by combining a specified aqueous dispersoid composed of acrylonitrile and styrol with a specified water soln. of a prim. condensate of aminoplasts or phenoplasts, specified red phosphorus and polyphosphoric acid ammonium, and coating and penetrating them in a polymer nonwoven cloth. CONSTITUTION: (a) A 50%-aqueous dispersoid of a thermal cross-linkable copolymer (having a glass transition pt. of +33 deg.C) of acrylonitrile and styrol is compounded with (b) a 60%-water soln. contg. hydroxymethyl groups of a prim. condensate of aminoplasts or phenoplasts at a ratio of 10:0.8-0.8:2.0, (c) red phosphorus of 0.05-0.10mm grain size and (d) polyphosphoric acid ammonium of 0.025-0.075mm grain size are added to mix an adhesive system at ratios: c:d=1:10 and (a+b):(+d)=1:0.9. The adhesive system is coated on and penetrated in a polymer nonwoven cloth at a ratio of 3-60g/m<2> (dry).