Multi-layer flexible metal-clad laminate and manufacturing method thereof

1. A multi-layer flexible metal-clad laminate comprising:

a metal foil laminated on one surface or both surfaces of a multi-layer polyimide film,

wherein the multi-layer polyimide film includes an n th polyimide layer, an n+1 th polyimide layer, and a mixed layer of the n th polyimide layer and the n+1 th polyimide layer,

wherein the metal foil includes a plurality of roughening particles attached on the metal foil surface adjacent to the multi-layer polyimide film,

wherein the metal foil satisfies the following Equations 1 to 3:

0.5≤ Rz M ≤1.2  [Equation 1]

0.01≤ Ra M ≤0.19  [Equation 2]

0.06≤ Dp M ≤0.09  [Equation 3]

wherein in Equation 1, Rz M is a ten-point average surface roughness (Rz) of the surface of the metal foil adjacent to the surface of the polyimide layer, in Equation 2, Ra M is an arithmetic average surface roughness (Ra) of the surface of the metal foil adjacent to the surface of the polyimide layer, in Equation 3, Dp M is an average particle size of roughening particles, and each unit thereof is μm, and n is an integer selected from 1 to 3, and

wherein the multi-layer polyimide film obtained by removing the metal foil from the multi-layer flexible metal-clad laminate satisfies the following Equations 8 and 9:

25≤ Tp≤ 90  [Equation 8]

40≤Haze≤60  [Equation 9]

wherein in Equation 8, Tp is a transmittance (%) of a straight light of the multi-layer polyimide film measured after the metal foil is removed, and in Equation 9, Haze is a turbidity (%) of the multi-layer polyimide film measured after the metal foil is removed.

2. The multi-layer flexible metal-clad laminate of claim 1 , wherein the n th polyimide layer and the n+1 th polyimide layer are laminated without performing a drying process to form the mixed layer of the n th polyimide layer and the n+1 th polyimide layer between the n th polyimide layer and the n+1 th polyimide layer.

3. The multi-layer flexible metal-clad laminate of claim 2 , wherein the mixed layer of the n th polyimide layer and the n+1 th polyimide layer satisfies the following Equations 4 and 5:

Min( CTE n ,CTE n+1 )≤ CTE M ≤Max( CTE n ,CTE n+1 )  Equation 4

Min( Tg n ,Tg n+1 )≤ Tg M ≤Max( Tg n ,Tg n+1 )  Equation 5

wherein

in Equation 4, CTE n is a coefficient of linear thermal expansion of the n th polyimide layer, CTE n+1 is a coefficient of linear thermal expansion of the n+1 th polyimide layer, CTE M is a coefficient of linear thermal expansion of the mixed layer of the n th polyimide layer and the n+1 th polyimide layer, Min(CTE n , CTE n+1 ) is the minimum of CTE n and CTE n+1 , and Max (CTE n , CTE n+1 ) is the maximum of CTE n and CTE n+1 , and

in Equation 5, Tg n is a glass transition temperature of the n th polyimide layer, Tg n+1 is a glass transition temperature of the n+1 th polyimide layer, Tg M is a glass transition temperature of the mixed layer of the n th polyimide layer and the n+1 th polyimide layer, Min (Tg n , Tg n+1 ) is the minimum of Tg n and Tg n+1 , and Max (Tg n , Tg n+1 ) is the maximum of Tg n and Tg n+1 .

4. The multi-layer flexible metal-clad laminate of claim 1 , wherein the metal foil is any one selected from copper, aluminum, iron, silver, palladium, nickel, chromium, molybdenum, tungsten or alloys thereof.

5. The multi-layer flexible metal-clad laminate of claim 1 , wherein each layer of the multi-layer polyimide film has a thickness of 1 to 30 μm.

6. The multi-layer flexible metal-clad laminate of claim 1 , wherein the multi-layer polyimide film satisfies the following Equations 6 and 7:

0.5 Rz M ≤Rz P ≤1.0 Rz M   Equation 6

0.5 Ra M ≤Ra P ≤1.0 Ra M   Equation 7

and wherein in Equation 6, Rz P is a ten-point average surface roughness (Rz) of the multi-layer polyimide film and Rz M is the ten-point average surface roughness (Rz) of the surface of the metal foil adjacent to the surface of the polyimide layer, and in Equation 7, Ra P is an arithmetic average surface roughness (Ra) of the multi-layer polyimide film and Ra M is the arithmetic average surface roughness (Ra) of the surface of the metal foil adjacent to the surface of the polyimide layer.

7. A manufacturing method of a multi-layer flexible metal-clad laminate including a metal-clad laminated on one surface or both surfaces of a multi-layer polyimide film, the manufacturing method comprising:

laminating an n th polyimide layer and an n+1 th polyimide layer on one surface of the metal-clad without performing a drying process to form a multi-layer polyimide layer having a mixed layer of the n th polyimide layer and the n+1 th polyimide layer,

wherein the metal-clad includes a plurality of roughening particles attached to the surface of the metal-clad adjacent to the multi-layer polyimide film,

wherein the metal-clad satisfies the following Equations 1 to 3:

0.5< Rz M <1.2  [Equation 1]

0.01< Ra M <0.19  [Equation 2]

0.06< Dp M <0.09  [Equation 3]

wherein n is an integer selected from 1 to 3, in Equation 1, Rz M is a ten-point average surface roughness (Rz) of the surface of the metal-clad adjacent to the surface of the polyimide layer, in Equation 2, Ra M is an arithmetic average surface roughness (Ra) of the surface of the metal-clad adjacent to the surface of the polyimide layer, in Equation 3, Dp M is an average particle size of the roughening particles and each unit thereof is μm, and

wherein the multi-layer polyimide film obtained by removing the metal-clad from the multi-layer flexible metal-clad laminate satisfies the following Equations 8 and 9:

25≤ Tp≤ 90  Equation 8

40≤Haze≤60  Equation 9

wherein in Equation 8, Tp is a transmittance (%) of a straight light of the multi-layer polyimide film measured after the metal-clad is removed, and in Equation 9, Haze is a turbidity (%) of the multi-layer polyimide film measured after the metal-clad is removed.

8. The manufacturing method of claim 7 , wherein the mixed layer of the n th polyimide layer and the n+1 th polyimide layer satisfies the following Equations 4 and 5:

Min( CTE n ,CTE n+1 )≤ CTE M ≤Max( CTE n ,CTE n+1 )  [Equation 4]

Min( Tg n ,Tg n+1 )≤ Tg M ≤Max( Tg n ,Tg n+1 )  [Equation 5]

(wherein n is an integer selected from 1 to 10,

in Equation 4, CTE n is a coefficient of linear thermal expansion of the n th polyimide layer, CTE n+1 is a coefficient of linear thermal expansion of the n+1 th polyimide layer, CTE M is a coefficient of linear thermal expansion of the mixed layer of the n th polyimide layer and the n+1 th polyimide layer, Min(CTE n , CTE n+1 ) is the minimum of CTE n and CTE n+1 , and Max(CTE n , CTE n+1 ) is the maximum of CTE n and CTE n+1 , and

in Equation 5, Tg n is a glass transition temperature of the n th polyimide layer, Tg n+1 is a glass transition temperature of the n+1 th polyimide layer, Tg M is a glass transition temperature of the mixed layer of the n th polyimide layer and the n+1 th polyimide layer, Min (Tg n , Tg n+1 ) is the minimum of Tg n and Tg n+1 , and Max (Tg n , Tg n+1 ) is the maximum of Tg n and Tg n+1 ).

9. The manufacturing method of claim 7 , wherein the metal-clad is any one selected from copper, aluminum, iron, silver, palladium, nickel, chromium, molybdenum, tungsten or alloys thereof.

10. The manufacturing method of claim 7 , wherein the laminating is performed by one or two or more coating methods selected from a group consisting of a knife coating, a roll coating, a slot-die coating, a lip-die coating, a slide coating, and a curtain coating.

11. The manufacturing method of claim 7 , wherein the multi-layer flexible metal-clad laminate is double-sided and is manufactured by forming the multi-layer polyimide film on one surface of the metal-clad and then adhering the multi-layer polyimide film and a second metal-clad by a laminating method.