Adhesive Film and Use Thereof

A method for producing an adhesive film comprising:

• concurrently supplying, into an extruder having a dice for extruding in two or more layers, an organic solvent solution containing a polyamide acid that is a precursor of the highly heat resistant polyimide, and either an organic solvent solution containing the thermoplastic polyimide, or an organic solvent solution containing a polyamide acid that is a precursor of the thermoplastic polyimide, and extruding the organic solvent solutions via an outlet of the dice to form a thin film having at least two layers;
• continuously supplying the extruded organic solvent solutions on a smooth-surfaced supporter, and volatilizing off at least part of an organic solvent or organic solvents from the thin film on the supporter in order to obtain a laminate film that is self-supportive;
• and
• holding both edges of the laminate film in the TD direction and subjecting the laminate film to imidation while elongating the laminate film in the TD direction to an elongation ratio of greater than 1.0,
• wherein the adhesive film includes (i) a heat resistant layer containing a highly heat resistant polyimide, and (ii) an adhesive layer on at least one surface of the heat resistant layer, the adhesive layer containing a thermoplastic polyimide,
• a thermal shrinkage ratio in a TD direction is +0.01% or more, and a thermal shrinkage ratio in an MD direction is −0.02% or less, and
• the heat resistant layer and the adhesive layer on the at least one surface of the heat resistant layer are formed by a coextrusion-flow casting method.

A method for producing an adhesive film,

• forming a gel film by shaping, into a film-like shape, an organic solvent solution containing a polyamide acid, which is a precursor of the highly heat resistant polyimide;
• applying on at least one surface of the gel film an organic solvent solution containing a thermoplastic polyimide or an organic solvent solution containing a polyamide acid that is a precursor of the thermoplastic polyimide, and heating the gel film on which the organic solvent solution is applied;
• and
• holding both edges of the laminate film in the TD direction and subjecting the laminate film to imidation while elongating the laminate film in the TD direction to an elongation ratio of greater than 1.0,
• wherein the adhesive film includes (i) a heat resistant layer containing a highly heat resistant polyimide, and (ii) an adhesive layer on at least one surface of the heat resistant layer, the adhesive layer containing a thermoplastic polyimide,
• a thermal shrinkage ratio in a TD direction is +0.01% or more, and a thermal shrinkage ratio in an MD direction is −0.02% or less, and
• the heat resistant layer and the adhesive layer on the at least one surface of the heat resistant layer are formed by a gel applying method.