FLEXIBLE CIRCUIT BOARD

• Main Authors: SHIGEMATSU SAKURAKO, NAKABAYASHI TOSHIYUKI, FUJIMOTO NOBUETSU
• Format: Patent
• Language: English; Japanese
• Published: 06.09.2018
• Subjects: CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; PERFORMING OPERATIONS; PRINTED CIRCUITS; TRANSPORTING

PROBLEM TO BE SOLVED: To provide a flexible circuit board having superior durability against bending and folding, which is arranged so that a break of circuitry and a crack of the board can be prevented.SOLUTION: A flexible circuit board comprises: a polyimide layer having a thickness within a range of 5 to 30 μm and a tensile elasticity within a range of 4 to 10 GPa; and copper interconnections laminated on at least one face of the polyimide layer made of copper foil, and having a thickness within a range of 6 to 20 μm and a tensile elasticity within a range of 25 to 35 GPa. The flexible circuit board has a ten-point average roughness (Rz) within a range of 0.7 to 2.2 μm about the copper foil on the face on a side where the circuit board is in contact with the polyimide layer, and a creasing habit coefficient [PF] within a range of 0.96±0.025, which is calculated according to the formula (1) in a bending test with a gap 0.3 mm. [In the formula (1), |ε| denotes an absolute value of a flexural average strain value of the copper interconnections and εc denotes a tensile elastic limit strain of the copper interconnections].SELECTED DRAWING: None 【課題】配線回路の断線や割れを防止する、優れた耐折り曲げ性を有するフレキシブル回路基板を提供する。【解決手段】フレキシブル回路基板は、厚み５〜３０μｍの範囲内、引張弾性率４〜１０ＧＰａの範囲内のポリイミド層と、ポリイミド層の少なくとも一方の面に積層された厚み６〜２０μｍの範囲内、引張弾性率２５〜３５ＧＰａの範囲内の銅箔からなる銅配線と、を有している。フレキシブル回路基板は、ポリイミド層と接する側の面の銅箔の十点平均粗さ（Ｒｚ）が０．７〜２．２μｍの範囲内であり、かつ、ギャップ０．３ｍｍでの折り曲げ試験での、下記式（１）によって計算される折れ癖係数［ＰＦ］が０．９６±０．０２５の範囲にある。［式（１）において、|ε|は銅配線の屈曲平均ひずみ値の絶対値であり、εｃは銅配線の引張弾性限界ひずみである。］【選択図】なし