Patent ID: 8586190

Claim:
An inorganic-organic hybrid film-coated stainless steel foil for an electrically insulating substrate material, comprising a stainless steel foil substrate coated on one surface or both surfaces with a first inorganic-organic hybrid film, wherein said first inorganic-organic hybrid film comprises a skeleton formed of an inorganic three-dimensional network structure mainly comprising a siloxane bond, with at least one crosslinked oxygen of said skeleton being replaced by a first organic group and/or a hydrogen atom, and the ratio [H]/[Si] between hydrogen concentration [H] (mol/l) and silicon concentration [Si] (mol/l) in said first inorganic-organic hybrid film satisfies the condition of 0.3≦[H]/[Si]≦3; wherein said organic group of said first inorganic-organic hybrid film is an alkyl group having 1 to 4 carbons; wherein a thickness Tf of said inorganic-organic hybrid film satisfies the condition 0.5 μm≦Tf≦2 μm; wherein the thickness Tf of said inorganic-organic hybrid film and a thickness Ts of said stainless steel foil substrate satisfy the condition of Tf≦Ts/40; wherein the thickness Tf of said inorganic-organic hybrid film and an average roughness Ras of the surface of said stainless steel foil substrate satisfy the condition of Ras≦Tf/2; and wherein said inorganic-organic hybrid film-coated stainless steel foil further comprises an uppermost film of an inorganic layer of SiO 2 or a second inorganic-organic hybrid film on said first inorganic-organic hybrid film; wherein said second inorganic-organic hybrid film comprises a skeleton formed of an inorganic three-dimensional network structure mainly comprising a siloxane bond, with at least one crosslinked oxygen of said skeleton being replaced by a second organic group and/or a hydrogen atom, and the ratio [H]/[Si] between hydrogen concentration [H] (mol/l) and silicon concentration [Si] (mol/l) in said film satisfies the condition of [H]/[Si]<1.0.