POLYIMIDE RESIN

To provide a polyimide resin capable of forming a polyimide film with low Df, which can form a CCL with low transmission loss in a high frequency band.SOLUTION: The polyimide resin comprises a constitutional unit (A) derived from a tetracarboxylic anhydride, and a constitutional unit (B) derived from a diamine. The constitutional unit (A) derived from a tetracarboxylic anhydride includes a constitutional unit (A1) derived from an ester bond-containing tetracarboxylic anhydride, and a constitutional unit (A2) derived from a biphenyl backbone-containing tetracarboxylic anhydride. The constitutional unit (B) derived from a diamine includes a constitutional unit (B1) derived from a biphenyl backbone-containing diamine. The content of the constitutional unit (A1) is 15-75 mol%, the content of the constitutional unit (A2) is 25-85 mol%, the total content of the constitutional unit (A1) and the constitutional unit (A2) is 60 mol% or more, and the content of the constitutional unit (B1) is more than 30 mol%.SELECTED DRAWING: None 【課題】高周波帯域での伝送損失の低いＣＣＬを形成し得る、Ｄｆの低いポリイミド系フィルムを形成可能なポリイミド系樹脂を提供する。【解決手段】テトラカルボン酸無水物由来の構成単位（Ａ）とジアミン由来の構成単位（Ｂ）とを含有し、テトラカルボン酸無水物由来の構成単位（Ａ）が、エステル結合含有テトラカルボン酸無水物由来の構成単位（Ａ１）及びビフェニル骨格含有テトラカルボン酸無水物由来の構成単位（Ａ２）を含み、ジアミン由来の構成単位（Ｂ）が、ビフェニル骨格含有ジアミン由来の構成単位（Ｂ１）を含み、前記構成単位（Ａ１）の含有量が１５～７５モル％であり、前記構成単位（Ａ２）の含有量が２５～８５モル％であり、前記構成単位（Ａ１）と前記構成単位（Ａ２）との合計含有量が６０モル％以上であり、前記構成単位（Ｂ１）の含有量が３０モル％を超える、ポリイミド系樹脂。【選択図】なし