Abstract: A polyimide precursor having a structural unit represented by the following formula (1):

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: 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 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.