Abstract: A porous resin film for a metal layer laminate board and a metal layer laminate board are provided to suppress damage to a metal layer disposed on an inner peripheral surface of a through hole and to have excellent electrical connection reliability even under the high temperature environment. The porous resin film for a metal layer laminate board is used in lamination of a metal layer. The porous resin film for a metal layer laminate board has a minimum thermal expansion coefficient X in a plane direction perpendicular to a thickness direction and a thermal expansion coefficient Z in the thickness direction. In the porous resin film for a metal layer laminate board, a ratio (Z/X) of the thermal expansion coefficient Z in the thickness direction to the minimum thermal expansion coefficient X is 3.5 or less.

Abstract: To provide a polyimide film and a metal-clad laminate that are excellent in low hygroscopic dielectric properties, the polyimide film has a dielectric loss tangent of less than 0.010 after being immersed in water at 25° C. for 24 hours.

Abstract: A polyimide film is a reaction product of a diamine component and an acid dianhydride component. The diamine component contains p-phenylenediamine, a first aromatic diamine, and a second aromatic diamine. The first aromatic diamine and the second aromatic diamine are different from each other and represented by the following formula (1): In the diamine component, each of a molar fraction of the p-phenylenediamine, a molar fraction of the first aromatic diamine, and a molar fraction of the second aromatic diamine is 10% by mole or more and 70% by mole or less. The acid dianhydride component contains an acid dianhydride containing an aromatic ring.

Abstract: A film 1 for a metal layer laminate board is used for lamination of a metal layer 5. The film 1 for a metal layer laminate board includes a porous resin layer 2 and a skin layer 3 in order in a thickness direction. The porous resin layer 2 has an average pore size W in the entire thickness direction of 7.0 ?m or less. The porous resin layer 2 includes a first region 11 to a fifth region 15 disposed in order in a direction away from the skin layer 3 when the porous resin layer 3 is equally divided into five in the thickness direction. A ratio (A1/A5) of an average pore size A1 of the first region 11 to an average pore size A5 of the fifth region 15 is 0.45 or more and 1 or less.

Abstract: A porous polyimide film is provided to suppress an increase in a dielectric loss tangent even when immersed in water. In the porous polyimide film, a difference between a dielectric loss tangent T1 after being left to stand for 24 hours under an atmosphere of 25° C. and relative humidity of 50% and a dielectric loss tangent T2 after immersion in water for 24 hours under an atmosphere of 25° C. is 0.0030 or less.

Abstract: A porous polyimide film has a low dielectric loss tangent. The porous polyimide film is a reaction product of a diamine component and an acid dianhydride component. The diamine component contains an aromatic diamine represented by the following formula (1). (In formula, Y represents at least one selected from the group consisting of a single bond, —COO—, —S—, —CH(CH3)—, —C(CH3)2—, —CO—, —NH—, and —NHCO—.) The porosity is 50% or more.

Abstract: A porous resin film for a metal layer laminate board and a metal layer laminate board are provided to suppress damage to a metal layer disposed on an inner peripheral surface of a through hole and to have excellent electrical connection reliability even under the high temperature environment. The porous resin film for a metal layer laminate board is used in lamination of a metal layer. The porous resin film for a metal layer laminate board has a minimum thermal expansion coefficient X in a plane direction perpendicular to a thickness direction and a thermal expansion coefficient Z in the thickness direction. In the porous resin film for a metal layer laminate board, a ratio (Z/X) of the thermal expansion coefficient Z in the thickness direction to the minimum thermal expansion coefficient X is 3.5 or less.