Flexible metal laminate and preparation method of the same

1. A flexible metal laminate comprising a porous polyimide resin layer, comprising:

30 wt % to 95 wt % of a polyimide resin; and

5 wt % to 70 wt % of hollow fluorinated resin particles having a mean outer diameter of 0.1 μm to 10.0 μm;

wherein the flexible metal laminate comprises a metal film deposited on at least one side of the porous polyimide resin layer comprising at least one metal selected from the group consisting of copper, iron, nickel, titanium, aluminum, silver, gold, and alloys thereof, and

wherein the hollow fluorinated resin particles comprise an outer wall including a fluorinated resin, and a hollow core part surrounded by the outer wall and having a maximum cross-sectional diameter of 0.05 μm to 9.5 μm.

2. The flexible metal laminate according to claim 1 , wherein the volume ratio of the hollow core part of the hollow fluorinated resin in the porous polyimide resin layer is 0.1 vol % to 5 vol %.

3. The flexible metal laminate according to claim 1 , wherein the hollow fluorinated resin particle is an open hollow particle or a closed hollow particle.

4. The flexible metal laminate according to claim 1 , wherein the porous polyimide resin layer has a density of 1.2 g/cm 3 to 1.9 g/cm 3 .

5. The flexible metal laminate according to claim 1 , wherein the polyimide resin comprises a repeat unit of the following Chemical Formula 1:

wherein, in Chemical Formula 1, n is n integer of 1 to 300,

Y1 is a tetravalent functional group selected from the group consisting of the following Chemical Formulae 28 to 30, and

X is a divalent functional group of the following Chemical Formula 35,

wherein, in Chemical Formulae 28 to 30, ‘*’ denotes a bonding point,

wherein, in Chemical Formula 35, R1 and R2 may identical to or different from each other, and are independently —CH3, —CH2CH3, —CH2CH2CH2CH3, —CF3, —CF2CF3, —CF2CF2CF3, or —CF2CF2CF2CF3.

6. The flexible metal laminate according to claim 1 , wherein the porous polyimide resin layer has a thickness of 0.1 μm to 200 μm.

7. The flexible metal laminate according to claim 1 , wherein the fluorinated resin particle includes at least one compound selected from the group consisting of polytetrafluoroethylene (PTFE), a tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), an ethylene-tetrafluoroethylene copolymer resin (ETFE), a tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE/CTFE), and an ethylene-chlorotrifluoroethylene resin (ECTFE).

8. The flexible metal laminate according to claim 1 , wherein the porous polyimide resin layer has a dielectric constant of 2.7 or less at 5 GHz.

9. The flexible metal laminate according to claim 1 , wherein the flexible metal laminate comprises one or more porous polyimide resin layers.

10. The flexible metal laminate according to claim 1 , further comprising one or more thermoplastic polyimide resin layers having a thickness of 0.1 μm to 200 μm.

11. A method for preparing the flexible metal laminate of claim 1 comprising the steps of: raising the temperature of a polyimide resin precursor composition comprising 30 wt % to 95 wt % of a polyamic acid resin and 5 wt % to 70 wt % of fluorinated resin particles to 340° C. to 370° C. while varying a temperature rising speed at temperature ranges below and exceeding 280° C. to 320° C., and cooling the temperature-raised resin composition to form a porous polyimide resin layer; and depositing a metal film comprising at least one metal selected from the group consisting of copper, iron, nickel, titanium, aluminum, silver, gold, and alloys thereof on at least one side of the porous polyimide resin layer.

12. The method according to claim 11 , wherein the temperature-raising of a polyimide resin precursor composition comprising 30 wt % to 95 wt % of a polyamic acid resin and wt % 5 to 70 wt % of fluorinated resin particles to 340° C. to 370° C. while varying a temperature rising speed at temperature ranges below and exceeding 280° C. to 320° C. comprises:

firstly raising the temperature of the resin composition at the speed of 3° C./min to 10° C./min at a temperature range below 280° C. to 320° C.; and

secondly raising the temperature of the firstly temperature-raised resin composition to 340° C. to 370° C. at the speed of 0.2° C./min to 2° C./min at a temperature range exceeding 280° C. to 320° C.

13. The method according to claim 11 , wherein the step of forming the porous polyimide resin layer further comprises cooling the temperature-raised resin composition to the temperature of 200° C. to 280° C.

14. The method according to claim 13 , wherein the step of forming the porous polyimide resin layer comprises cooling the temperature-raised resin composition to the temperature of 200° C. to 280° C. at the speed of 3° C./min to 10° C./min.

15. The method according to claim 11 , wherein the step of forming the porous polyimide resin layer comprises:

firstly raising the temperature of the resin composition at the speed of 3° C./min to 10° C./min at a temperature range below 300° C.;

secondly raising the temperature of the firstly temperature-raised resin composition to 340° C. to 370° C. at the speed of 0.2° C./min to 2° C./min at a temperature range exceeding 300° C.; and

cooling the secondly temperature-raised resin composition to the temperature of 230° C. to 270° C. at the speed of 4° C./min to 8° C./min.

16. The method according to claim 11 , wherein the step of forming the porous polyimide resin layer further comprises coating the resin composition on a substrate to a thickness of 0.1 μm to 200 μm before the temperature raising.

17. The method according to claim 11 , wherein the step of depositing the metal film on at least one side of the porous polyimide resin layer comprises:

applying a pressure of 500 Kgf to 3000 Kgf at the temperature of 250° C. to 450° C., so as to deposit the metal film on at least one side of the porous polyimide resin layer.