Polyimide film and adhesive film and flexible metal-clad laminate both obtained with the same

1. A polyimide film produced by imidizing a polyamic acid prepared by reacting an aromatic diamine and an aromatic dianhydride,

the polyimide film being prepared from a polyimide polymer comprising a block component derived from a thermoplastic polyimide and wherein the ultimately obtained polyimide film is non-thermoplastic, the polyimide film satisfying all the conditions (i) to (iv):

(i) an inflection point of a storage modulus of the polyimide film is in a range of 270 to 340° C.;

(ii) a peak top of tan δis in a range of 320 to 410° C., where tan δis a value obtained by dividing a loss modulus by the storage modulus;

(iii) the storage modulus at 380° C. is in a range of 0.4 to 2.0GPa; and

(iv) the storage modulus α1 (GPa) at the inflection point and the storage modulus α2 (GPa) at 380° C. is in a range of the following Equation (1):

85≧{(α1-α2)/α1}×100 ≧65  (1),

wherein measurement for the storage modulus, the inflection point of the storage modulus, the peak top of tan δ, and the storage modulus at 380° C. is done at 5Hz.

2. The polyimide film as set forth in claim 1 , having a tensile modulus of 6.0 GPa or greater.

3. The polyimide film as set forth in claim 1 , wherein the polyimide film has a moisture expansion coefficient of 13pprn/° C. or less, the moisture expansion coefficient being measured after the polyimide film is kept at 50° C. and 40% RH. for 3 hours and then at 80% RH. for 3 hours.

4. The polyimide film as set forth in claim 1 , having a linear expansion coefficient of 15ppm/° C. or less from 100° C. to 200° C.

5. The polyimide film as set forth in claim 1 , having an angle of molecular orientation axis in a range of −15 degrees to 15 degrees to a film transfer direction (MD direction).

6. The polyimide film as set forth in claim 5 , wherein the polyimide film is obtained by a method for producing an organic insulating film, the method including:

(A) polymerizing to form a polyamic acid;

(B) flow-casting and spreading a composition containing the polyamic acid and an organic solvent onto a support and forming a gel film;

(C) peeling off the resulting gel film from the support and holding the gel film at its edges; and

(D) transferring the film held at its edges in a heating furnace, wherein the step (D) at least includes the step of (D-1) transferring the film held in a manner such that the film has substantially no tension in a film width direction (TD direction) in at least part of the step (D).

7. The polyimide film as set forth in claim 1 being obtained by performing imidization with a polyamic acid solution obtained by carrying out the steps of:

(a) reacting, in an organic polar solvent, an aromatic acid dianhydride and an aromatic diamine compound being greater in a molar amount than the aromatic acid dianhydride, so as to obtain a prepolymer having an amino group at each end;

(b) sequentially, further adding an aromatic diamine compound; and

(c) performing polymerization after further adding an aromatic acid dianhydride in an amount that makes up a substantially equimolar amount of the aromatic acid dianhydride to the aromatic diamine in an overall process.

8. The polyimide film as set forth in claim 7 , wherein the aromatic diamine compound used in step (a) is a diamine having a soft structure, and the aromatic diamine compound used in step (b) is a diamine having a rigid structure.

9. The polyimide film as set forth in claim 8 , wherein 3,4′-diaminodiphenylether is 10mol % or more to the whole diamine component in the production of the polyimide film.

10. An adhesive film comprising:

a polyimide film as set forth in claim 1 and

an adhesive layer on at least one side of the polyimide film, the adhesive layer containing a thermoplastic polyimide.

11. The adhesive film as set forth in claim 10 , wherein:

the thermoplastic polyimide has a glass transition temperature (Tg) of 230° C. or higher.

12. The adhesive film as set forth in claim 10 being 15μm or less in film thickness.

13. A flexible metal-clad laminate produced by adhering an adhesive film as set forth in claim 10 and a metal foil by using a heat roll laminating apparatus having one or more pairs of metal rollers.

14. The flexible metal-clad laminate as set forth in claim 13 , wherein the step of adhering includes:

performing lamination in which a protective material is provided between the metal foil and one roller, the protective film being made of a non-thermoplastic polyimide or a thermoplastic polyimide which has a glass transition temperature (Tg) that is higher than a lamination temperature by 50° C. or more; and

separating the protective material after post-lamination cooling.

15. The flexible metal-clad laminate as set forth in claim 14 , wherein before the separating of the protective material but after the lamination, a laminate in which the protective film and the flexible metal-clad laminate are attached with each other is touched with a heating roller in a period in a range of 0.1 to 5 seconds, and the laminate is cooled before separating the protective material.

16. The flexible metal-clad laminate as set forth in claim 13 , wherein a dimensional change of the flexible metal-clad laminate before and after heating the flexible metal-clad laminate at 250° C. for 30 minutes after the removal of the metal foil is in a range of −0.04 to +0.04% in each of an MD direction and a TD direction.

17. The flexible metal-clad laminate as set forth in claim 13 , wherein the flexible metal-clad laminate has an adhesive film of 15μm in thickness, and a dimensional change of the flexible metal-clad laminate before and after heating the flexible metal-clad laminate at 250° C. for 30 minutes after the removal of the metal foil is in a range of −0.05 to +0.05% in each of an MD direction and a TD direction.