To provide a technique for preventing the pin removing failure in a polyimide multilayered film after baking in manufacturing the polyimide multilayered film by a casting film forming method while enhancing the peelability of a multilayered gel film from a support even in a case that the peelability of the multilayered film from the support is enhanced by employing a chemical imidation method and effectively avoiding the ply separation of the multilayered gel film.

For example, in a case that a multilayered liquid film 30 comprising thermoplastic polyimide varnish/heat-resistant polyimide varnish/thermoplastic polyimide varnish is formed on an endless belt and converted to the multilayered gel film 40, a liquid film 32 comprising the heat-resistant polyimide varnish is formed as a wide liquid film of which the width is larger than that of each of other liquid films 31 and 33 and both end parts of the multilayered liquid film 30 are formed into a single-layered structure composed only of the wide liquid film. In this case, it is preferable to use a multilayered coextrusion die wherein an inner deckle is inserted in a flow channel. The multilayered gel film 40 may be baked in a state that a tenter pin 17 is thrust in the end part of the single-layered structure to fix the single-layered structure.

COPYRIGHT: (C)2006,JPO&NCIPI