Preparation of flexible copper foil/polyimide laminate
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsMasahiro Usuki, Makoto Fujiwara, Shigehiro Hoshida, Michio Aizawa, Tadashi Amano
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Abstract
A flexible metal foil/polyimide laminate is prepared by applying a polyamic acid varnish onto a very thin copper foil on a carrier, semi-drying the varnish, laminating a polyimide film to the varnish-coated copper foil using a hot roll press, and heat treating the laminate for solvent removal and imidization in an atmosphere having a controlled oxygen concentration. A polyimide adhesive layer resulting from the imidization of polyamic acid has a thickness of up to 6 μm, the sum of the thicknesses of the polyimide film and the polyimide adhesive layer is up to 25 μm. The polyimide adhesive layer has a Tg>400° C.
Claims25
A method for preparing a flexible metal foil/polyimide laminate, comprising:
- applying a polyamic acid varnish onto a very thin copper foil having a thickness of up to 9 μm supported on a carrier,
- semi-drying the varnish until a solvent content of the varnish becomes 40 to 100% by weight based on varnish solids,
- laminating a polyimide film to the varnish-coated copper foil using a hot roll press, and
- heat treating the laminate for removing the residual solvent in the varnish and imidizing the polyamic acid in an atmosphere having an oxygen concentration of up to 2% by volume,
- wherein a polyimide adhesive layer resulting from the imidization of polyamic acid has a thickness of up to 6 μm, the sum of the thickness of the polyimide film and the thickness of the polyimide adhesive layer is up to 25 μm, and the polyimide adhesive layer has a glass transition temperature of higher than 400° C.
Dependencies are inferred from the claim text.