JP5329491B2 - Copper foil for flexible printed wiring board and method for producing the same - Google Patents
Copper foil for flexible printed wiring board and method for producing the same Download PDFInfo
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Abstract
Description
本発明は、フレキシブルプリント配線板に配線材料として使用される銅箔および当該銅箔を配線材料として使用したフレキシブルプリント配線板に関する。 The present invention relates to a copper foil used as a wiring material for a flexible printed wiring board and a flexible printed wiring board using the copper foil as a wiring material.
柔軟性のある絶縁基板と銅箔配線部から構成されるフレキシブルプリント配線板（ＦＰＣ）は、電子機器内の屈曲変形が繰り返し加えられ部位、例えばハードディスク内の可動部、携帯電話のヒンジ部やスライド摺動部、プリンターのヘッド部、光ピックアップ部、ノートＰＣの可動部等の配線に広く用いられている。近年の高密度実装化に伴い屈曲部の曲率半径が小さくなり，電解銅箔等の従来の銅箔を用いたＦＰＣでは、銅箔の疲労破壊により配線が断線するという問題が生じていた。 A flexible printed wiring board (FPC) composed of a flexible insulating substrate and a copper foil wiring portion is repeatedly subjected to bending deformation in an electronic device, such as a movable portion in a hard disk, a hinge portion or a slide of a mobile phone. Widely used for wiring of sliding parts, printer head parts, optical pickup parts, notebook PC movable parts, and the like. With the recent high-density mounting, the curvature radius of the bent portion is reduced, and the FPC using the conventional copper foil such as electrolytic copper foil has a problem that the wiring is disconnected due to fatigue failure of the copper foil.
そこで、特開２０１０−３４５４１号公報では、銅等の立方晶系の結晶構造を有する金属を用いたＦＰＣにおいて、所定の角度を有して屈曲させた場合に耐屈曲性が向上することに着目し、屈曲部の稜線から厚み方向に切った際の配線の断面が、［００１］を晶帯軸として（１００）から（１１０）への回転方向における（20 １ ０）から（１ 20 ０）の範囲に含まれたいずれかの面に主方位をなすように配線することを提案している。この方位関係は、屈曲部における稜線が金属箔の長さ方向と２．９°〜８７．１°の角度を成すように配線することに相当する。ここで、銅箔の長さ方向とは、圧延銅箔の場合は圧延機での圧延方向に、電解銅箔の場合は電解ラインでの通箔方向に相当する。 In view of this, in JP 2010-34541 A, attention is paid to the fact that the FPC using a metal having a cubic crystal structure such as copper is improved in bending resistance when bent at a predetermined angle. Then, the cross section of the wiring when cut in the thickness direction from the ridgeline of the bent portion is (20 1 0) to (1 200) in the rotation direction from (100) to (110) with [001] as the crystal zone axis. It is proposed to perform wiring so as to have a main orientation on any surface included in the range. This orientation relationship corresponds to wiring so that the ridge line at the bent portion forms an angle of 2.9 ° to 87.1 ° with the length direction of the metal foil. Here, the length direction of the copper foil corresponds to a rolling direction in a rolling mill in the case of a rolled copper foil, and corresponds to a foil passing direction in an electrolytic line in the case of an electrolytic copper foil.
同様に、特開２０１０−５６１２８号公報では、可撓性配線基板の製造方法として、金属箔の長手方向に対し３°〜８７°傾けた方向に配線を形成する製造方法が提案されている。 Similarly, Japanese Unexamined Patent Application Publication No. 2010-56128 proposes a manufacturing method for forming a wiring in a direction inclined by 3 ° to 87 ° with respect to the longitudinal direction of the metal foil as a manufacturing method of the flexible wiring board.
本発明は、特許文献１に記載の発明の改良発明を提供すること、すなわち、屈曲部における稜線が金属箔の長さ方向と２．９°〜８７．１°の角度を成すように配線されたＦＰＣついて、配線材料である銅箔を改良することにより、その耐屈曲性をさらに改善することを課題とする。 The present invention provides an improvement of the invention described in Patent Document 1, that is, the ridgeline in the bent portion is wired so as to form an angle of 2.9 ° to 87.1 ° with the length direction of the metal foil. Further, an object of the present invention is to further improve the bending resistance of the FPC by improving the copper foil as a wiring material.
本発明者等は、鋭意検討した結果、ＦＰＣに用いる銅箔の伸び特性を改良することで上記課題を解決し得ることを見出し、本発明を完成した。 As a result of intensive studies, the present inventors have found that the above problems can be solved by improving the elongation characteristics of the copper foil used in the FPC, and have completed the present invention.
すなわち、本発明は一側面において、柔軟性絶縁基板と銅箔から形成された配線とを備え、配線の少なくとも一箇所の屈曲部における稜線が銅箔の長さ方向と２．９〜８７．１°の角度を成すフレキシブルプリント配線板の配線部材として用いられる銅箔であって、３６０℃×６分間の熱処理を施して該銅箔を再結晶させると、銅箔表面の厚み方向のＸ線回折で求めた（２００）面の強度（Ｉ）が微粉末銅のＸ線回折で求めた（２００）面の強度（Ｉ0）に対してＩ／Ｉ0≧２５である立方体集合組織が発現し、さらに銅箔の長さ方向に対し４５°方向の伸びが、銅箔の長さ方向に対し０°および９０°方向の伸びの４倍以上である伸び特性が発現するレキシブルプリント配線板用銅箔である。 That is, in one aspect, the present invention includes a flexible insulating substrate and a wiring formed from a copper foil, and a ridge line at at least one bent portion of the wiring is 2.9 to 87.1 in the length direction of the copper foil. A copper foil used as a wiring member of a flexible printed wiring board having an angle of °. When heat treatment is performed at 360 ° C. for 6 minutes to recrystallize the copper foil, X-ray diffraction in the thickness direction of the copper foil surface A cubic texture with an I / I 0 ≧ 25 of the strength (I 0 ) of the (200) plane obtained by X-ray diffraction of the (200) plane determined by X-ray diffraction was developed. Further, copper for a flexible printed wiring board that exhibits elongation characteristics in which the elongation in the 45 ° direction with respect to the length direction of the copper foil is at least four times the elongation in the 0 ° and 90 ° directions with respect to the length direction of the copper foil. It is a foil.
本発明に係るフレキシブルプリント配線板用銅箔は一実施形態において、銅箔の長さ方向に対し４５°方向の伸びが、２０％以上である。 In one embodiment, the copper foil for a flexible printed wiring board according to the present invention has an elongation in the 45 ° direction of 20% or more with respect to the length direction of the copper foil.
本発明に係るフレキシブルプリント配線板用銅箔は別の一実施形態において、Ａｇ、Ｓｎ、Ｃｒ、Ｆｅ、Ｚｎ及びＺｒよりなる群から選択される合金元素の１種又は２種以上を合計で０〜１質量％含有し残部が銅及び不可避的不純物からなるタフピッチ銅ベースまたは無酸素銅ベースの圧延銅箔である。 In another embodiment, the copper foil for a flexible printed wiring board according to the present invention includes one or more alloy elements selected from the group consisting of Ag, Sn, Cr, Fe, Zn, and Zr in a total of 0. A tough pitch copper base or oxygen-free copper base rolled copper foil containing ˜1% by mass with the balance being copper and inevitable impurities.
本発明に係るフレキシブルプリント配線板用銅箔は更に別の一実施形態において、Ａｇを０．０１〜０．０５質量％含有し残部が銅及び不可避的不純物からなる、タフピッチ銅ベースの圧延銅箔である。 In yet another embodiment, the copper foil for flexible printed wiring board according to the present invention is a tough pitch copper-based rolled copper foil containing 0.01 to 0.05% by mass of Ag and the balance being copper and inevitable impurities. It is.
本発明に係るフレキシブルプリント配線板用銅箔は更に別の一実施形態において、Ｓｎを０．００１〜０．０１質量％含有し残部が銅及び不可避的不純物からなる、無酸素銅ベースの圧延銅箔である。 In yet another embodiment, the copper foil for a flexible printed wiring board according to the present invention is an oxygen-free copper-based rolled copper containing 0.001 to 0.01% by mass of Sn and the balance being copper and inevitable impurities. It is a foil.
本発明に係るフレキシブルプリント配線板用銅箔は更に別の一実施形態において、厚さが６〜３５μｍである。 In yet another embodiment, the copper foil for flexible printed wiring board according to the present invention has a thickness of 6 to 35 μm.
本発明に係るフレキシブルプリント配線板用銅箔は更に別の一実施形態において、本発明に係る銅箔表面の片面又は両面に粗化処理を施したフレキシブルプリント配線板用銅箔である。 In yet another embodiment, the copper foil for a flexible printed wiring board according to the present invention is a copper foil for a flexible printed wiring board obtained by subjecting one or both surfaces of the copper foil surface according to the present invention to a roughening treatment.
本発明は別の一側面において、柔軟性絶縁基板の片面又は両面に、本発明に係る銅箔が熱処理工程を経て積層されてなるフレキシブル銅張積層板である。 Another aspect of the present invention is a flexible copper-clad laminate in which the copper foil according to the present invention is laminated on one side or both sides of a flexible insulating substrate through a heat treatment step.
本発明に係るフレキシブル銅張積層板は一実施形態において、熱処理工程における材料の加熱温度をＴ（℃）、加熱時間をt（ｈ）としたときに、（Ｔ＋２７３）×（１４＋ｌｏｇｔ）の値が６０００〜１００００となる条件で該熱処理が行われている。 In one embodiment, the flexible copper clad laminate according to the present invention has a value of (T + 273) × (14 + logt), where T (° C.) is the heating temperature of the material in the heat treatment step and t (h) is the heating time. The heat treatment is performed under conditions of 6000 to 10,000.
本発明は更に別の一側面において、本発明に係るフレキシブル銅張積層板を材料として製造したフレキシブルプリント配線板であって、柔軟性絶縁基板と銅箔から形成された配線とを備え、配線の少なくとも一箇所の屈曲部における稜線が銅箔の長さ方向と２．９〜８７．１°の角度を成すフレキシブルプリント配線板である。 According to another aspect of the present invention, there is provided a flexible printed wiring board manufactured using the flexible copper clad laminate according to the present invention as a material, comprising a flexible insulating substrate and a wiring formed from a copper foil. It is a flexible printed wiring board in which the ridge line in at least one bent portion forms an angle of 2.9 to 87.1 ° with the length direction of the copper foil.
本発明は更に別の一側面において、インゴットを熱間圧延した後、冷間圧延と焼鈍を繰り返して、最終冷間圧延で所定厚みに仕上げる工程を含み、該最終冷間圧延において圧延加工度を９３．０〜９９．９％、圧延油温度を２０〜３０℃の範囲に調整する本発明に係る銅箔の製造方法である。 In yet another aspect, the present invention includes a step of hot rolling an ingot, then repeating cold rolling and annealing, and finishing to a predetermined thickness by final cold rolling, and in the final cold rolling, the rolling work degree is increased. 93.0 to 99.9%, and the rolling oil temperature is adjusted to a range of 20 to 30 ° C.
本発明によれば、耐屈曲性が向上されたＦＰＣを提供することが可能となる。 According to the present invention, it is possible to provide an FPC with improved bending resistance.
（ＦＰＣの配線）
図１に示すように、ＦＰＣをＵ字状に屈曲させると、その外側（曲率半径を有した内接円が形成される方とは反対側）にＵ字の頂点を通る稜線が形成される。屈曲部の形状がＶ字状であればＶ字の頂点を通る稜線が形成される。本発明のＦＰＣでは、この屈曲部の頂点が描く稜線と銅箔の長さ（ＬＤ）方向との角度（α）（０°≦α≦９０°）が２．９〜８７．１°の範囲になるように配線する。前記特許文献１で開示されているように、配線材料として立方体集合組織が発達した銅箔を用いた場合、この角度関係をとることでＦＰＣの耐屈曲性が大幅に向上する。このような配線状態の例を図２の（ａ）及び（ｂ）に示す。ちなみに、図２の（ｃ）及び（ｄ）はＬＤ方向に対し稜線が直交した状態（α＝９０°）である。αが１１．４〜７８．６°であれば屈曲耐久性がより一層向上する。さらに好ましくはαが２６．６〜６３．４°、最も好適にはαが３０°又は６０°である。
(FPC wiring)
As shown in FIG. 1, when the FPC is bent in a U-shape, a ridge line passing through the apex of the U-shape is formed on the outer side (the side opposite to the side where the inscribed circle having a radius of curvature is formed). . If the shape of the bent portion is V-shaped, a ridge line passing through the vertex of the V-shape is formed. In the FPC of the present invention, the angle (α) (0 ° ≦ α ≦ 90 °) between the ridge line drawn by the apex of the bent portion and the length (LD) direction of the copper foil is in the range of 2.9 to 87.1 °. Wire so that As disclosed in Patent Document 1, when a copper foil having a cubic texture is used as a wiring material, the bending resistance of the FPC is greatly improved by taking this angular relationship. Examples of such wiring states are shown in FIGS. Incidentally, (c) and (d) of FIG. 2 are states in which the ridge lines are orthogonal to the LD direction (α = 90 °). When α is 11.4 to 78.6 °, the bending durability is further improved. More preferably, α is 26.6 to 63.4 °, and most preferably α is 30 ° or 60 °.
配線の幅、形状、パターン等については特に制限はなく、ＦＰＣの用途、搭載される電子機器等に応じて適宜設計すればよいが、本発明の屈曲部構造は屈曲耐久性に優れることから、例えば配線に対する曲げ応力を小さくするためにヒンジ部の回動軸に対して斜め方向に配線するようなことをあえてする必要がなく、屈曲部における稜線に対して直交する方向に沿った配線、すなわち必要最小限の最短距離での配線が可能である。例えば、図２（ａ）及び（ｂ）は、携帯電話のヒンジ部等に使用されるＦＰＣであり、柔軟性樹脂基板１と金属箔から形成した配線２とコネクタ端子３とを有する例である。図２（ａ）及び（ｂ）のいずれも、中央付近に屈曲部における稜線の位置を示しており、この稜線は、配線２を形成する銅箔のＬＤ方向に対してα°の角度を有する。ここで、図２（ａ）は、両端のコネクタ端子３の途中、稜線付近で配線が斜めに形成された例であるが、図２（ｂ）のようにコネクタ端子３間を最短距離で配線することも可能である。なお、折り畳み式携帯電話等のように、屈曲部における稜線の位置が固定される場合のほか、スライド式携帯電話等のように屈曲部における稜線が移動するようなスライド摺動屈曲であってもよい。また、本発明におけるＦＰＣは、柔軟性絶縁基板の少なくとも片面に銅箔からなる配線を備えるが、必要に応じて柔軟性絶縁基板の両面に銅箔を備えるようにしてもよい。 The width, shape, pattern, etc. of the wiring are not particularly limited, and may be appropriately designed according to the use of the FPC, the mounted electronic device, etc., but the bent portion structure of the present invention is excellent in bending durability. For example, in order to reduce the bending stress on the wiring, it is not necessary to dare to wire in an oblique direction with respect to the rotation axis of the hinge portion, and the wiring along the direction orthogonal to the ridge line in the bent portion, that is, Wiring with the shortest possible minimum distance is possible. For example, FIGS. 2A and 2B are FPCs used for a hinge portion of a mobile phone and the like, which is an example having a flexible resin substrate 1, a wiring 2 formed from a metal foil, and a connector terminal 3. . 2A and 2B both show the position of the ridge line in the bent portion near the center, and this ridge line has an angle of α ° with respect to the LD direction of the copper foil forming the wiring 2. . Here, FIG. 2A is an example in which the wiring is formed obliquely in the vicinity of the ridge line in the middle of the connector terminals 3 at both ends. However, as shown in FIG. It is also possible to do. In addition to the case where the position of the ridgeline in the bent portion is fixed as in a folding mobile phone, etc., the slide sliding bend in which the ridgeline in the bent portion moves as in a slide-type mobile phone, etc. Good. Moreover, although FPC in this invention is equipped with the wiring which consists of copper foils on at least one surface of a flexible insulated substrate, you may make it equip both surfaces of a flexible insulated substrate with copper foil as needed.
（銅箔の集合組織）
角度αの制御による屈曲性改善効果を得るためには、熱処理を施して再結晶させたときに銅箔が立方体集合組織を発現する必要がある。その必要なレベルは、銅箔表面の厚み方向に対しＸ線回折を行った際に得られる（２００）面の強度をＩ、微粉末銅（ランダム方位）のＸ線回折で求めた（２００）面の強度をＩ0としたときに、Ｉ／Ｉ0≧２５で与えられる。Ｘ線回折はＣｏ管球を用いて行う。Ｉ／Ｉ0が２５未満であると、αを如何に調整しても満足できる耐屈曲性が得られない。Ｉ／Ｉ0はより好ましくは４０以上であり、更により好ましくは５０以上であり、更により好ましくは６０以上であり、例えば２５〜７５である。
(Copper foil texture)
In order to obtain the bendability improving effect by controlling the angle α, the copper foil needs to develop a cubic texture when recrystallized by heat treatment. The required level was determined by X-ray diffraction of (200) plane obtained by X-ray diffraction with respect to the thickness direction of the copper foil surface by I and X-ray diffraction of fine powder copper (random orientation) (200). When the surface strength is I 0 , I / I 0 ≧ 25. X-ray diffraction is performed using a Co tube. If I / I 0 is less than 25, satisfactory bending resistance cannot be obtained no matter how α is adjusted. I / I 0 is more preferably 40 or more, even more preferably 50 or more, still more preferably 60 or more, for example 25 to 75.
（銅箔の伸び特性）
本発明者らは、前記熱処理後に立方体集合組織を発現する銅箔について、熱処理後の伸びの異方性を制御することにより、αを前記範囲に調整したときの耐屈曲性がさらに向上することを見出した。具体的には、引張り試験により求めた銅箔の伸び（破断伸び）について、銅箔の長さ方向と成す角度が０°、９０°、４５°となる三方向に引張り試験を行い伸びを求めた際に、４５°方向の伸びが０°および９０°方向の伸びの４倍以上になるように、銅箔を調質すると耐屈曲性が著しく向上した。そこで、４５°方向の伸びを０°および９０°方向の伸びの４倍以上、好ましくは５倍以上、例えば４〜６倍に規定する。４５°方向の伸びが２０％であればより好ましく、２５％以上あれば更により好ましく、３０％以上あれば更により好ましく、３５％以上あればもっとも好ましく、例えば２０〜４０％である。ここで、銅箔の長さ方向とは、圧延銅箔の場合は圧延機での圧延方向に、電解銅箔の場合は電解ラインでの通箔方向に相当する。
(Elongation characteristics of copper foil)
The present inventors further improve the bending resistance when α is adjusted to the above range by controlling the anisotropy of elongation after the heat treatment for the copper foil that expresses the cubic texture after the heat treatment. I found. Specifically, the elongation (breaking elongation) of the copper foil obtained by the tensile test is obtained by performing a tensile test in three directions in which the angle formed with the length direction of the copper foil is 0 °, 90 °, and 45 °. When the copper foil was tempered so that the elongation in the 45 ° direction was at least 4 times the elongation in the 0 ° and 90 ° directions, the bending resistance was remarkably improved. Therefore, the elongation in the 45 ° direction is specified to be 4 times or more, preferably 5 times or more, for example, 4 to 6 times the elongation in the 0 ° and 90 ° directions. The elongation in the 45 ° direction is more preferably 20%, even more preferably 25% or more, even more preferably 30% or more, and most preferably 35% or more, for example, 20 to 40%. Here, the length direction of the copper foil corresponds to a rolling direction in a rolling mill in the case of a rolled copper foil, and corresponds to a foil passing direction in an electrolytic line in the case of an electrolytic copper foil.
（銅箔の熱処理）
前記熱処理工程は、銅箔をポリイミド樹脂フィルムに貼り合わせるときの熱処理工程を想定している。ＦＰＣの素材であるフレキシブル銅張積層板（以下、ＦＣＣＬ）は、ポリイミド系樹脂基板の片面又は両面に、銅箔を貼り合わせることにより製造する場合が多い。この貼り合わせの際に熱処理が施される。例えば、三層ＦＣＣＬではエポキシ等の熱硬化性樹脂からなる接着剤を用いて、銅箔とポリイミド樹脂フィルムを貼り合わせるが、この接着剤を硬化させるために、１３０〜１７０℃の温度で０．５〜５０時間程度の加熱処理を行う。また、二層ＦＣＣＬの製造方法の一つであるキャスティング法では、ポリイミド樹脂の前駆体であるポリアミック酸を含むワニスを、銅箔上に塗布して加熱硬化させ、銅箔上にポリイミド被膜を形成する。この加熱硬化処理では、３００〜４５０℃程度の温度で１〜４０分程度加熱する。
(Heat treatment of copper foil)
The heat treatment step assumes a heat treatment step when the copper foil is bonded to the polyimide resin film. A flexible copper-clad laminate (hereinafter referred to as FCCL), which is an FPC material, is often manufactured by bonding a copper foil to one or both sides of a polyimide resin substrate. A heat treatment is performed during the bonding. For example, in the three-layer FCCL, an adhesive made of a thermosetting resin such as epoxy is used to bond a copper foil and a polyimide resin film. In order to cure the adhesive, the temperature is 130.degree. Heat treatment is performed for about 5 to 50 hours. Moreover, in the casting method which is one of the manufacturing methods of the two-layer FCCL, a varnish containing polyamic acid which is a precursor of a polyimide resin is applied on a copper foil and cured by heating to form a polyimide coating on the copper foil. To do. In this heat curing treatment, heating is performed at a temperature of about 300 to 450 ° C. for about 1 to 40 minutes.
前記の熱処理工程における代表的な熱負荷は、材料温度３６０℃として６分間加熱するときの熱負荷に相当する。材料温度３６０℃として６分間加熱後に上述したような集合組織および伸び特性の規定を満たすことができる銅箔は、ＦＣＣＬの製造時に実施される典型的な熱処理工程の後に同様の集合組織および伸び特性の規定を満たすことができる。 A typical heat load in the heat treatment step corresponds to a heat load when heating at a material temperature of 360 ° C. for 6 minutes. A copper foil that can meet the texture and elongation property specifications as described above after heating at a material temperature of 360 ° C. for 6 minutes has similar texture and elongation properties after a typical heat treatment step performed during FCCL manufacture. Can be satisfied.
（銅箔の製造方法）
銅箔が上記集合組織および伸び特性を有していれば、成分（添加元素、不純物）、製造方法（電解／圧延）、製造条件によらず、本発明の効果は発現する。本発明の銅箔は、例えば、次のような圧延プロセスにより製造することができる。
(Manufacturing method of copper foil)
If the copper foil has the texture and elongation characteristics described above, the effects of the present invention are exhibited regardless of the components (additive elements, impurities), the production method (electrolysis / rolling), and the production conditions. The copper foil of this invention can be manufactured by the following rolling processes, for example.
本発明の一実施形態においては、Ａｇ、Ｓｎ、Ｃｒ、Ｆｅ、ＺｎおよびＺｒよりなる群から選択される合金元素の１種又は２種以上を合計で１質量％以下含有し、残部が銅及び不可避的不純物からなる圧延銅箔を使用することができる。 In one embodiment of the present invention, it contains 1% by mass or less of one or more alloy elements selected from the group consisting of Ag, Sn, Cr, Fe, Zn and Zr, with the balance being copper and A rolled copper foil made of inevitable impurities can be used.
合金元素は必ずしも添加しなくてもよいが、Ａｇ、Ｓｎ、Ｃｒ、Ｆｅ、ＺｎおよびＺｒの一種以上を微量に添加することにより、前述した集合組織および伸び特性の規定を満足することが容易になる。ただし、添加濃度が少なすぎると伸び特性を改善する効果が得られないので、合金元素は合計で０．００３質量％以上添加することが好ましく、合計で０．００５質量％以上添加することがより好ましい。一方、合金元素の添加量が多くなりすぎると、集合組織を改善する効果が減じ、また導電率が低下する。そのため、合金元素の添加量は合計で１．０質量％以下に制限すべきであり、好ましくは合計で０．１質量％以下、より好ましくは合計で０．０５質量％以下に制限すべきである。 The alloy element does not necessarily have to be added, but it is easy to satisfy the above-mentioned provisions of the texture and elongation characteristics by adding a trace amount of one or more of Ag, Sn, Cr, Fe, Zn and Zr. Become. However, if the addition concentration is too low, the effect of improving the elongation characteristics cannot be obtained. Therefore, it is preferable to add 0.003% by mass or more of alloy elements in total, and more preferable to add 0.005% by mass or more in total. preferable. On the other hand, when the addition amount of the alloy element is too large, the effect of improving the texture is reduced, and the electrical conductivity is lowered. Therefore, the total amount of alloy elements should be limited to 1.0% by mass or less, preferably 0.1% by mass or less, more preferably 0.05% by mass or less in total. is there.
合金元素を添加するベースのＣｕ材料としてはＪＩＳ−１０２０規定の無酸素銅またはＪＩＳ−１１００規定のタフピッチ銅が適する。無酸素銅溶湯の酸素濃度は通常０．００１質量％以下であり、タフピッチ銅溶湯の酸素濃度は通常０．０１〜０．０５質量％である。
Ｃｕよりも酸化しやすいＳｎ、Ｃｒ、Ｆｅ、ＺｎおよびＺｒのいずれか１種以上の元素を採用する場合は、添加元素が銅箔中で酸化物を形成し屈曲性を低下させることを避けるために、無酸素銅溶湯中に添加するのが一般的である。
ＡｇはＣｕより酸化しにくいので、タフピッチ銅溶湯中、無酸素銅溶湯中ともに添加できる。ただし、酸素濃度が０．０５質量％を超えると、酸化銅粒子が増大して屈曲性が低下するため、該タフピッチ銅中の酸素濃度は０．０５質量％以下に調整することが好ましい。
なお、溶解工程での酸素濃度の調整は、溶湯のカーボンシール、大気解放等の当業者公知の技術により行うことができる。
As the base Cu material to which the alloy element is added, oxygen-free copper defined by JIS-1020 or tough pitch copper defined by JIS-1100 is suitable. The oxygen concentration of the oxygen free molten copper is usually 0.001% by mass or less, and the oxygen concentration of the tough pitch copper molten metal is usually 0.01 to 0.05% by mass.
When employing at least one element of Sn, Cr, Fe, Zn and Zr, which is easier to oxidize than Cu, to prevent the additive element from forming an oxide in the copper foil and lowering the flexibility. In general, it is added to the oxygen-free copper melt.
Since Ag is less susceptible to oxidation than Cu, it can be added both in the tough pitch copper melt and in the oxygen free copper melt. However, if the oxygen concentration exceeds 0.05% by mass, the copper oxide particles increase and the flexibility decreases, so the oxygen concentration in the tough pitch copper is preferably adjusted to 0.05% by mass or less.
Note that the oxygen concentration in the melting step can be adjusted by techniques known to those skilled in the art, such as carbon sealing of molten metal and release to the atmosphere.
本発明に係る圧延銅箔の好適な例として、Ａｇを０．０１〜０．０５質量％添加したタフピッチ銅（例えば特開２０００−２１２６６１号公報）およびＳｎを０．００１〜０．０１質量％添加した無酸素銅（例えば特開２００８−１０６３１３号公報）が挙げられる。 As a suitable example of the rolled copper foil according to the present invention, tough pitch copper to which Ag is added in an amount of 0.01 to 0.05% by mass (for example, Japanese Patent Laid-Open No. 2000-212661) and Sn in an amount of 0.001 to 0.01% by mass. An oxygen-free copper added (for example, JP-A-2008-106313) can be mentioned.
圧延銅箔の製造プロセスでは、電気銅等の純銅原料を溶解して合金元素を添加した後、この溶湯を鋳造し、厚みが１００〜３００ｍｍ程度のインゴットを製造する。このインゴットを熱間圧延して厚み１０ｍｍ程度（例：５〜２０ｍｍ）の板にした後、冷間圧延と焼鈍を繰り返して薄くし、最後に冷間圧延（最終冷間圧延）で所定厚みの箔に仕上げる。通常、最終冷間圧延後の銅箔には粗化処理が行われており、投錨効果による樹脂との密着性の改善に効果がある。粗化処理の方法としては、ブラスト処理、機械研磨、電解研磨、化学研磨及び電着粒のめっき等の方法が知られており、これらの中でも特に粗化めっきは多用されている。この技術は、銅箔表面に樹枝状又は小球状に銅などの金属を多数電着せしめて微細な凹凸を形成するものである。 In the manufacturing process of rolled copper foil, after melting pure copper raw materials such as electrolytic copper and adding an alloy element, the molten metal is cast to produce an ingot having a thickness of about 100 to 300 mm. This ingot is hot-rolled into a plate having a thickness of about 10 mm (example: 5 to 20 mm), then cold-rolled and annealed repeatedly to make it thin, and finally cold-rolled (final cold-rolled) to a predetermined thickness. Finish in foil. Usually, the copper foil after the final cold rolling is subjected to a roughening treatment, which is effective in improving the adhesion with the resin due to the anchoring effect. As a method of roughening treatment, methods such as blasting, mechanical polishing, electrolytic polishing, chemical polishing and plating of electrodeposited grains are known. Of these, roughening plating is particularly frequently used. In this technique, fine irregularities are formed by electrodepositing a large number of metals such as copper in a dendritic or small spherical shape on the surface of a copper foil.
先述した集合組織および伸び特性は、最終冷間圧延の条件を調整することで得られる。最終圧延の加工度は９３％以上、より好ましくは９５％以上とする。ここで、加工度ｒ（％）は、ｒ＝（ｔ0−ｔ）／ｔ0×１００（ｔ：圧延後の厚み，ｔ0：圧延前の厚み）で定義される。加工度が９３％未満の場合、熱処理後の銅箔のＩ／Ｉ0が２５を下回る傾向にある。また、他の製造条件を調整しても、熱処理後の銅箔の４５°方向の伸びを０°および９０°方向の伸びの４倍以上に調整することが困難となる。加工度の上限値は、集合組織および伸び特性の点からは特に規制されないが、加工度が極度に高くなると圧延中に銅箔が破断しやすくなるので通常は９９．９％以下である。 The texture and elongation characteristics described above can be obtained by adjusting the conditions of final cold rolling. The degree of work of final rolling is 93% or more, more preferably 95% or more. Here, the working degree r (%) is defined by r = (t 0 −t) / t 0 × 100 (t: thickness after rolling, t 0 : thickness before rolling). When the degree of work is less than 93%, the I / I 0 of the copper foil after heat treatment tends to be less than 25. Even if other manufacturing conditions are adjusted, it becomes difficult to adjust the elongation in the 45 ° direction of the copper foil after the heat treatment to 4 times or more of the elongation in the 0 ° and 90 ° directions. The upper limit of the workability is not particularly restricted in terms of texture and elongation characteristics, but is usually 99.9% or less because the copper foil tends to break during rolling when the workability becomes extremely high.
伸びの特性には最終冷間圧延時の圧延油の温度が影響を及ぼす。加工度を９３％以上に調整することに加え、圧延油の温度を２０〜３０℃の範囲に調整することにより、４５°方向の伸びを０°および９０°方向の伸びの４倍以上とし、また４５°方向の伸びを２０％以上とすることができる。圧延油の温度が３０℃を超えると、４５°方向の伸びが０°および９０°方向の伸びの４倍未満になったり、４５°方向の伸びが２０％未満になったりしやすい。銅箔を圧延中の加工熱により圧延油温度は上昇し、圧延速度や１パスあたりの圧下量を大きくすると、生産効率は向上するが圧延油温度が上昇する。従来は、生産効率を重視し、３０℃超の圧延油温度で圧延が行われていた。圧延油温度の下限値については、極端に温度が低い場合を除くと集合組織や伸び特性に影響しないものの、２０℃未満に制御しようとすると生産効率が極度に低下するため、２０℃以上に調整することが好ましい。 The elongation characteristics are affected by the temperature of the rolling oil during final cold rolling. In addition to adjusting the degree of processing to 93% or more, by adjusting the temperature of the rolling oil in the range of 20 to 30 ° C., the elongation in the 45 ° direction is 4 times or more of the elongation in the 0 ° and 90 ° directions, Further, the elongation in the 45 ° direction can be 20% or more. When the temperature of the rolling oil exceeds 30 ° C, the 45 ° elongation tends to be less than 4 times the 0 ° and 90 ° elongation, or the 45 ° elongation tends to be less than 20%. The rolling oil temperature rises due to the processing heat during the rolling of the copper foil. When the rolling speed and the amount of reduction per pass are increased, the production efficiency is improved, but the rolling oil temperature rises. Conventionally, rolling was performed at a rolling oil temperature exceeding 30 ° C. with an emphasis on production efficiency. The lower limit of the rolling oil temperature is adjusted to 20 ° C or higher because production efficiency is extremely reduced if it is controlled to less than 20 ° C, although the texture and elongation characteristics are not affected unless the temperature is extremely low. It is preferable to do.
（銅箔の厚み）
本発明に使用される銅箔の厚みは特に制限されるものではないが、薄すぎるとＦＣＣＬの製造時にライン張力の調整が困難となる一方で、厚すぎるとＦＣＣＬの屈曲性が低下する傾向にあるので６〜３５μｍとするのが好ましく、９〜１８μｍとするのがより好ましい。
(Thickness of copper foil)
The thickness of the copper foil used in the present invention is not particularly limited, but if it is too thin, it becomes difficult to adjust the line tension during the production of FCCL, whereas if it is too thick, the flexibility of FCCL tends to decrease. Therefore, the thickness is preferably 6 to 35 μm, and more preferably 9 to 18 μm.
（ＦＣＣＬ）
ポリイミド系樹脂基板の片面又は両面に、熱処理工程（硬化工程）を経て、本発明に係る銅箔を積層することで、フレキシブル銅張積層板（ＦＣＣＬ）を製造することができる。ここでいう熱処理工程は樹脂を硬化させるための熱処理工程を指す。積層方法としては、上述したように、エポキシ等の熱硬化性樹脂からなる接着剤を用いて、銅箔とポリイミド樹脂フィルムを貼り合わせて、加熱処理を行う方法や、ポリイミド樹脂の前駆体であるポリアミック酸を含むワニスを、銅箔上に塗布して加熱硬化させ、銅箔上にポリイミド被膜を形成する方法がある。両面に銅箔を積層する場合は、片面銅張積層板を形成後、銅箔層を熱プレスにより圧着する方法や、２枚の銅箔層間にポリイミドフィルムを挟み、熱プレスにより圧着する方法がある。
(FCCL)
A flexible copper-clad laminate (FCCL) can be produced by laminating the copper foil according to the present invention on one or both sides of a polyimide resin substrate through a heat treatment step (curing step). The heat treatment step here refers to a heat treatment step for curing the resin. As described above, as a lamination method, using an adhesive made of a thermosetting resin such as epoxy, a copper foil and a polyimide resin film are bonded to each other, and a heat treatment is performed, or a polyimide resin precursor is used. There is a method in which a varnish containing polyamic acid is applied on a copper foil and cured by heating to form a polyimide coating on the copper foil. When laminating copper foil on both sides, after forming a single-sided copper clad laminate, there are a method of crimping the copper foil layer by hot pressing, and a method of sandwiching a polyimide film between two copper foil layers and crimping by hot pressing. is there.
熱処理工程の好ましい加熱条件は、加熱温度をＴ（℃）、加熱時間をｔ（ｈ）としたときに、（Ｔ＋２７３）×（１４＋ｌｏｇｔ）の値が６０００〜１００００となる条件である。ここで、ｌｏｇｔは１０を底とする常用対数である。（Ｔ＋２７３）×（１４＋ｌｏｇｔ）が６０００未満または１００００超の場合、Ｉ／Ｉ0を２５以上に調整することが難しくなることに加え、４５°方向の伸びを０°および９０°方向の伸びの４倍以上に調整すること、および４５°方向の伸びを２０％以上に調整することも難しくなる。なお、Ｔが４５０℃を超えるとＦＣＣＬに使用されているポリイミド系樹脂の分解が起こる場合がある一方で、Ｔが１６０℃未満だと樹脂の硬化が不十分になる。また、ｔが１．０を超えると生産効率が低下する一方で、ｔが０．０２未満だと樹脂の硬化が不十分になる。よって、熱処理工程におけるＴは１６０〜４５０℃が好ましく、２００〜４００℃がより好ましい。また、ｔは０．０２〜１．０が好ましく、０．０５〜０．５がより好ましい。なお、銅箔と樹脂の積層を、熱処理工程を経ずに接着剤によって行う方法もあるが、その場合は当該熱処理工程を積層後に実施すればよい。 Preferable heating conditions for the heat treatment step are conditions in which the value of (T + 273) × (14 + logt) is 6000 to 10,000 when the heating temperature is T (° C.) and the heating time is t (h). Here, logt is a common logarithm with base 10. When (T + 273) × (14 + logt) is less than 6000 or more than 10000, it becomes difficult to adjust I / I 0 to 25 or more, and elongation in the 45 ° direction is 4 of elongation in the 0 ° and 90 ° directions. It becomes difficult to adjust to more than twice and to adjust the elongation in the 45 ° direction to 20% or more. If T exceeds 450 ° C., the polyimide resin used in FCCL may be decomposed. On the other hand, if T is less than 160 ° C., curing of the resin becomes insufficient. On the other hand, when t exceeds 1.0, the production efficiency is lowered. On the other hand, when t is less than 0.02, curing of the resin becomes insufficient. Therefore, T in the heat treatment step is preferably 160 to 450 ° C, more preferably 200 to 400 ° C. Moreover, t is preferably 0.02 to 1.0, and more preferably 0.05 to 0.5. In addition, there is a method in which the copper foil and the resin are laminated with an adhesive without passing through the heat treatment step. In that case, the heat treatment step may be performed after the lamination.
ポリイミド系樹脂基板自体は任意の公知材料を使用すれば良く、特に制限はないが、二層ＦＣＣＬの場合、一般的には、公知のジアミンと酸無水物とを溶媒の存在下で反応させて得られるポリイミド前駆体樹脂（ポリアミック酸）を熱処理することによって形成することができる。ポリイミド系樹脂基板は、単層のみからなるものでも、複数層から形成されるものでもよい。複数層のポリイミド樹脂基板を形成する場合、異なる構成成分からなるポリイミド系樹脂基板の上に他のポリイミド樹脂を順次塗布して形成することができる。ポリイミド樹脂基板が３層以上からなる場合、同一の構成のポリイミド樹脂を２回以上使用してもよい。 Any known material may be used for the polyimide resin substrate itself, and there is no particular limitation. However, in the case of the two-layer FCCL, generally, a known diamine and an acid anhydride are reacted in the presence of a solvent. The resulting polyimide precursor resin (polyamic acid) can be formed by heat treatment. The polyimide resin substrate may be composed of only a single layer or may be formed of a plurality of layers. In the case of forming a polyimide resin substrate having a plurality of layers, it can be formed by sequentially applying other polyimide resins on a polyimide resin substrate made of different components. When the polyimide resin substrate is composed of three or more layers, the polyimide resin having the same configuration may be used twice or more.
（ＦＰＣ）
本発明に係るＦＣＣＬを材料として公知の手順に従って配線を形成し、フレキシブルプリント配線板（ＦＰＣ）を製造することが可能である。本発明が対象とするＦＰＣは柔軟性絶縁基板と銅箔から形成された配線とを備え、配線の少なくとも一箇所の屈曲部における稜線が銅箔の長さ方向と２．９〜８７．１°の角度を成す。絶縁基板の材料は典型的には樹脂であり、より典型的にはポリイミド樹脂である。このようなＦＰＣは、電子・電気機器においてハードディスク内の可動部、携帯電話のヒンジ部やスライド摺動部、プリンターのヘッド部、光ピックアップ部、ノートＰＣの可動部等に使用されるＦＰＣが該当する。
(FPC)
It is possible to manufacture a flexible printed wiring board (FPC) by forming wiring according to a known procedure using the FCCL according to the present invention as a material. The FPC targeted by the present invention includes a flexible insulating substrate and a wiring formed from a copper foil, and the ridge line at at least one bent portion of the wiring is 2.9 to 87.1 ° with respect to the length direction of the copper foil. Make an angle. The material of the insulating substrate is typically a resin, and more typically a polyimide resin. Such FPCs are FPCs used for movable parts in hard disks, hinge parts and slide sliding parts of mobile phones, printer head parts, optical pickup parts, movable parts of notebook PCs, etc. in electronic and electrical equipment. To do.
本発明に係るＦＰＣは、屈曲部が屈曲耐久性に優れていることから、摺動屈曲、折り曲げ屈曲、ヒンジ屈曲、スライド屈曲等において、屈曲部の曲率半径を小さくすることが可能である。その好適な曲率半径は、折り曲げ屈曲で０．３８〜２．０ｍｍ、摺動屈曲で１．２５〜２．０ｍｍ、ヒンジ屈曲で３．０〜５．０ｍｍ、スライド屈曲で０．３〜２．０ｍｍと厳しいものである。本発明のＦＰＣは０．３〜１ｍｍの狭いギャップでの屈曲性能が求められるスライド用途に特に効果を発揮する。 In the FPC according to the present invention, since the bent portion is excellent in bending durability, the radius of curvature of the bent portion can be reduced in sliding bending, bending bending, hinge bending, sliding bending, and the like. The preferred radius of curvature is 0.38 to 2.0 mm for bending and bending, 1.25 to 2.0 mm for sliding bending, 3.0 to 5.0 mm for hinge bending, and 0.3 to 2 mm for sliding bending. It is strict with 0 mm. The FPC of the present invention is particularly effective for slide applications that require bending performance in a narrow gap of 0.3 to 1 mm.
以下に本発明の実施例を比較例と共に示すが、これらの実施例は本発明及びその利点をよりよく理解するために提供するものであり、発明が限定されることを意図するものではない。 Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.
（１）銅箔の製造
後述する発明例及び比較例において製造した銅箔の一般的製造条件を説明する。
電気銅を溶解して酸素濃度を調整後、所定量のＡｇまたはＳｎを添加し、連続鋳造法により、幅が６００ｍｍ、厚みが２００ｍｍのインゴットを得た。このインゴットを８５０℃で３時間加熱し、熱間圧延により厚み１０ｍｍの板にした。次に、表面の酸化スケールを切削除去し、冷間圧延と再結晶焼鈍を繰り返し、最終の冷間圧延で厚みを１８〜９μｍに仕上げた。
最終冷間圧延における総加工度（Ｒ）を変化させるために、最終再結晶焼鈍（最終冷間圧延直前の焼鈍）を施す板厚を調整した。また、最終冷間圧延では、用いる圧延油の温度を種々変化させた。得られた圧延銅箔の片面に粗化めっきを施した。粗化めっきは、銅−コバルト−ニッケルめっきとし、銅を１７ｍｇ／ｄｍ2、コバルトを２０００μｇ／ｄｍ2、ニッケルを５００μｇ／ｄｍ2付着させた。
(1) Manufacture of copper foil General manufacturing conditions of the copper foil manufactured in the invention examples and comparative examples described later will be described.
After adjusting the oxygen concentration by dissolving electrolytic copper, a predetermined amount of Ag or Sn was added, and an ingot having a width of 600 mm and a thickness of 200 mm was obtained by a continuous casting method. The ingot was heated at 850 ° C. for 3 hours and formed into a plate having a thickness of 10 mm by hot rolling. Next, the oxide scale on the surface was cut off, cold rolling and recrystallization annealing were repeated, and the thickness was finished to 18 to 9 μm by the final cold rolling.
In order to change the total workability (R) in the final cold rolling, the thickness of the plate on which the final recrystallization annealing (annealing immediately before the final cold rolling) was performed was adjusted. In the final cold rolling, the temperature of the rolling oil used was variously changed. Roughening plating was given to one side of the obtained rolled copper foil. Roughening plating, copper - cobalt - and nickel plating, copper 17 mg / dm 2, cobalt 2000 [mu] g / dm 2, nickel was 500 [mu] g / dm 2 deposited.
（２）ＦＣＣＬの製造
ＦＣＣＬの製造ラインにおいて、前記銅箔の粗化めっきを施した面上に、市販のポリイミド前駆体ワニス（宇部興産株式会社製、商品名Ｕ−ワニス−Ａ）を塗布、乾燥し、銅箔層上にポリイミド前駆体樹脂層が形成された積層体を得た。この積層体をオーブンに入れて、Ｔ℃でｔ時間の熱処理を施し、厚さ１６μｍのポリイミド層（樹脂基板）と銅箔層とを有した片面ＦＣＣＬを得た。
(2) Production of FCCL In the production line of FCCL, a commercially available polyimide precursor varnish (trade name U-Varnish-A, manufactured by Ube Industries, Ltd.) is applied on the surface subjected to the rough plating of the copper foil. It dried and the laminated body in which the polyimide precursor resin layer was formed on the copper foil layer was obtained. This laminate was put in an oven and heat-treated at T ° C. for t hours to obtain a single-sided FCCL having a 16 μm thick polyimide layer (resin substrate) and a copper foil layer.
（３）ＦＰＣの製造
前記片面ＦＣＣＬから、銅箔の長手方向（ＬＤ方向）に沿って長さ２５０ｍｍ、幅方向に幅２００ｍｍの長方形サイズのシートを切り出した。このシートの銅箔側に所定のマスクを被せ、塩化鉄／塩化銅系溶液を用いてエッチングを行い、線幅（ｌ）０．１５ｍｍ、スペース幅（ｓ）０．２５ｍｍの直線状配線を有す回路を形成した。この製造過程において、図３に模式的に示すように、配線方向に対し直交する方向（屈曲部稜線）が銅箔のＬＤ方向に対してαの角度を成すように配線パターンを形成した。
次いで、それぞれの回路側の面に、エポキシ系接着剤を用いてカバー材（有沢製作所製ＣＶＫ−０５１５ＫＡ：厚さ１２．５μｍ）を積層した。接着剤からなる接着層の厚さは、銅箔回路のない部分では１５μｍであり、銅箔回路が存在する部分では６μｍであった。そして、配線方向に沿って長手方向に１５０ｍｍ、配線方向に直交する方向に幅８ｍｍとなるように切り出して片面ＦＰＣ４を得た。
(3) Manufacture of FPC A rectangular sheet having a length of 250 mm and a width of 200 mm along the longitudinal direction (LD direction) of the copper foil was cut out from the single-sided FCCL. The sheet is covered with a predetermined mask on the copper foil side and etched using an iron chloride / copper chloride solution to provide a linear wiring having a line width (l) of 0.15 mm and a space width (s) of 0.25 mm. A circuit was formed. In this manufacturing process, as schematically shown in FIG. 3, the wiring pattern was formed so that the direction orthogonal to the wiring direction (bent ridge line) formed an angle α with respect to the LD direction of the copper foil.
Subsequently, a cover material (CVK-0515KA manufactured by Arisawa Manufacturing Co., Ltd .: thickness 12.5 μm) was laminated on each circuit side surface using an epoxy adhesive. The thickness of the adhesive layer made of the adhesive was 15 μm in the portion without the copper foil circuit, and 6 μm in the portion where the copper foil circuit was present. And it cut out so that it might become 150 mm in a longitudinal direction along a wiring direction, and 8 mm in width in the direction orthogonal to a wiring direction, and single-sided FPC4 was obtained.
（４）評価
得られた粗化処理前の銅箔および試験用ＦＰＣについて、次の評価を行った。
（４−１）銅箔の成分
銅箔中の酸素濃度を不活性ガス溶融−赤外線吸収法で、Ｓｎ及びＡｇ濃度をＩＣＰ−質量分析法で分析した。ここで、Ｓｎ及びＡｇ分析には銅箔試料を用いたが、Ｏ分析には１．５ｍｍの板から採取した試料を用いた。これは、箔試料では質量に対する表面積の比率が非常に大きいため（例えば１ｇの試料の場合、厚さ１．５ｍｍの板の表面積は１．５ｃｍ2に対し、厚さ１０μｍの箔の表面積は２２０ｃｍ2）、銅箔試料を用いて酸素を分析すると、表面の酸化膜及び吸着水膜中の酸素が加算され、酸素分析値が銅箔中の酸素濃度より５０ｐｐｍ程度増加するためである。なお、箔試料を用い、これが無酸素銅ベースの箔であることを判定するためには、例えば、試料の金属組織を観察し、酸化物粒子が存在しないこと（直径２μｍ以上の酸化物粒子が０．０１個／ｍｍ2以下）を確認すればよい。また、タフピッチ銅ベースの箔であることを判定するためには、例えば、試料の金属組織を観察し、直径１〜５μｍの酸化銅粒子が１００個／ｍｍ2以上の頻度で分布していることを確認すればよい。ここでいう粒子の直径とは粒子を取り囲むことのできる最小円の直径を指す。
（４−２）立方体集合組織
銅箔にＦＣＣＬの作製時と同じ温度（Ｔ）同じ時間（ｔ）の熱処理を施した。その後、銅箔表面において厚さ方向にＸ線回折（理学電機株式会社製ＲＩＮＴ２０００）を行い、（２００）面強度の積分値（Ｉ）を求めた。この値をあらかじめ測定しておいた微粉末銅の（２００）面強度の積分値（Ｉ0）で割り、Ｉ／Ｉ0の値を計算した。なお、ピーク強度の積分値の測定では、Ｃｏ管球を用い、２θ＝５７〜６３°（θは回折角度）の範囲で行った。微粉末銅には関東化学株式会社製、銅（粉末）２Ｎ５（３２５ｍｅｓｈ，純度＞９９．５％）を用いた。
（４−３）銅箔の伸び
銅箔にＦＣＣＬの作製時と同じ温度（Ｔ）、同じ時間（ｔ）の熱処理を施した。その後、ＩＰＣ規格（ＩＰＣ−ＴＭ−６５０）に準じ室温で引張試験を行ない、試料が破断したときの伸びを求めた。試料形状は幅１２．７ｍｍ、長さ１５０ｍｍの短冊とし、試料の長さ方向が銅箔の圧延方向（ＬＤ方向）に対し０°、４５°および９０°の角度を成す三水準の方向に、それぞれ試料を採取した。伸び測定のための標点距離は５０ｍｍとし、引張り試験速度は５０ｍｍ／分とした。
（４−４）屈曲性
前記幅８ｍｍ、長さ１５０ｍｍのＦＰＣ試料に対し、信越エンジニアリング株式会社製ＩＰＣ屈曲試験機を用い耐屈曲性を評価した。ポリイミド層（樹脂基板）を外側にし、屈曲部稜線が配線方向と直交するように（屈曲部稜線がＬＤ方向とαの角度を成すように）ＦＰＣを固定し、曲率半径０．５ｍｍ、振動ストローク：２０ｍｍ、振動速度：１５００回／分の条件で繰り返しスライドさせた。その間、電気抵抗の増加で銅箔回路の疲労クラックの進展度合いをモニタリングし、回路の電気抵抗が初期値の２倍に達したストローク回数を屈曲寿命とした。
(4) Evaluation The following evaluation was performed about the obtained copper foil before roughening treatment and FPC for a test.
(4-1) Components of copper foil The oxygen concentration in the copper foil was analyzed by an inert gas melting-infrared absorption method, and the Sn and Ag concentrations were analyzed by ICP-mass spectrometry. Here, a copper foil sample was used for Sn and Ag analysis, but a sample collected from a 1.5 mm plate was used for O analysis. This is because the ratio of the surface area to the mass of the foil sample is very large (for example, in the case of a 1 g sample, the surface area of a 1.5 mm thick plate is 1.5 cm 2 while the surface area of a 10 μm thick foil is 220 cm. 2 ) When oxygen is analyzed using a copper foil sample, oxygen in the surface oxide film and adsorbed water film is added, and the oxygen analysis value is increased by about 50 ppm from the oxygen concentration in the copper foil. In addition, in order to determine that this is an oxygen-free copper-based foil using a foil sample, for example, the metal structure of the sample is observed and no oxide particles are present (oxide particles having a diameter of 2 μm or more are present). 0.01 piece / mm 2 or less) may be confirmed. Further, in order to determine that the foil is based on tough pitch copper, for example, the metal structure of the sample is observed, and copper oxide particles having a diameter of 1 to 5 μm are distributed at a frequency of 100 particles / mm 2 or more. You can confirm. The diameter of a particle here refers to the diameter of the smallest circle that can surround the particle.
(4-2) Cubic texture The copper foil was subjected to heat treatment at the same temperature (T) and the same time (t) as in the preparation of FCCL. Thereafter, X-ray diffraction (RINT2000 manufactured by Rigaku Corporation) was performed in the thickness direction on the surface of the copper foil, and an integral value (I) of (200) plane strength was obtained. This value was divided by the integral value (I 0 ) of the (200) plane strength of finely powdered copper that had been measured in advance, and the value of I / I 0 was calculated. Note that the measurement of the integrated value of the peak intensity was performed using a Co tube in the range of 2θ = 57 to 63 ° (θ is the diffraction angle). Copper (powder) 2N5 (325 mesh, purity> 99.5%) manufactured by Kanto Chemical Co., Ltd. was used as fine powder copper.
(4-3) Elongation of copper foil The copper foil was subjected to heat treatment at the same temperature (T) and the same time (t) as in the preparation of FCCL. Thereafter, a tensile test was performed at room temperature in accordance with the IPC standard (IPC-TM-650), and the elongation when the sample broke was determined. The sample shape is a strip with a width of 12.7 mm and a length of 150 mm, and the length direction of the sample is in three levels of directions at angles of 0 °, 45 ° and 90 ° with respect to the rolling direction of the copper foil (LD direction). Each sample was taken. The gauge distance for measuring the elongation was 50 mm, and the tensile test speed was 50 mm / min.
(4-4) Flexibility The flex resistance of the FPC sample having a width of 8 mm and a length of 150 mm was evaluated using an IPC flex tester manufactured by Shin-Etsu Engineering Co., Ltd. Fix the FPC so that the polyimide layer (resin substrate) is on the outside and the bend ridge line is orthogonal to the wiring direction (so that the bend ridge line forms an angle α with the LD direction), the radius of curvature is 0.5 mm, and the vibration stroke : 20 mm, vibration speed: repeatedly slid under conditions of 1500 times / minute. Meanwhile, the progress of fatigue cracks in the copper foil circuit was monitored by increasing the electrical resistance, and the number of strokes at which the electrical resistance of the circuit reached twice the initial value was defined as the flex life.
（例１）
Ａｇを０．０１８質量％添加したタフピッチ銅（酸素濃度０．０２質量％）を成分とする厚さ１２μｍの圧延銅箔を製造した。最終圧延は表１の３種類の条件で行ない、それぞれの銅箔に対しαを種々変化させてＦＰＣを製造し、その屈曲寿命を評価した。ＦＣＣＬの製造時の熱処理条件は３６０℃、６分間とした。評価結果を表１および図４に示す。
比較例２では最終圧延加工度が９０．０％と９３％未満であったため、Ｉ／Ｉ0が２５未満の１８であった。また、４５°方向の伸びは２０％に満たない１５．８％であり、０°および９０°方向の伸びと比較しても同レベルであった。比較例２の屈曲寿命はαによらず１．５万回に満たなかった。
比較例１では最終圧延加工度が９９．２％と９３％を超えたため、Ｉ／Ｉ0が６４となった。しかし、圧延油温度を３５℃としたため、４５°方向の伸びが０°および９０°方向の伸びに対し３倍程度となり、４５°方向の伸び値は１８．２％と２０％に満たなかった。比較例１の屈曲寿命は、αが０°および９０°に近い場合で３万回を越え、比較例２の屈曲寿命の２倍以上になった。屈曲部稜線をＬＤ方向に対し傾斜させることにより比較例１の屈曲寿命はさらに向上し、αが１５°〜７５°の場合で６万回を超え比較例２の屈曲寿命の４倍以上になった。比較例１の銅箔は、特許文献１（特開２０１０−３４５４１号公報）や特許文献２（特開２０１０−５６１２８号公報）に開示された銅箔に相当する。
発明例１では、最終圧延加工度を比較例１に合わせ、圧延油温度を２５℃とした。この銅箔のＩ／Ｉ0は比較例１と同様の６５となった。一方、４５°方向の伸びは０°および９０°方向の伸びに対し約５倍となり、４５°の伸びは３３．８％と２０％を超えた。発明例１の屈曲寿命は、αが０°および９０°に近い場合は比較例１と同レベルであったが、屈曲部稜線をＬＤ方向に対し傾斜させると比較例１以上に向上し、その屈曲寿命は比較例１より約２万回（３０％）長かった。
(Example 1)
A rolled copper foil having a thickness of 12 μm was prepared using tough pitch copper (oxygen concentration: 0.02 mass%) added with 0.018 mass% of Ag as a component. Final rolling was performed under the three conditions shown in Table 1. FPCs were produced by varying α for each copper foil, and the flex life was evaluated. The heat treatment conditions during the production of FCCL were 360 ° C. and 6 minutes. The evaluation results are shown in Table 1 and FIG.
In Comparative Example 2, the final rolling degree was 90.0%, which was less than 93%, so I / I 0 was 18, which was less than 25. Further, the elongation in the 45 ° direction was less than 20%, 15.8%, which was the same level as compared with the elongation in the 0 ° and 90 ° directions. The bending life of Comparative Example 2 was less than 15,000 times regardless of α.
In Comparative Example 1, the final rolling degree was 99.2%, which exceeded 93%, so that I / I 0 was 64. However, since the rolling oil temperature was set to 35 ° C., the 45 ° elongation was about three times the 0 ° and 90 ° elongation, and the 45 ° elongation was 18.2%, which was less than 20%. . The bending life of Comparative Example 1 exceeded 30,000 times when α was close to 0 ° and 90 °, and was more than twice the bending life of Comparative Example 2. By inclining the ridge line of the bent portion with respect to the LD direction, the bending life of Comparative Example 1 is further improved, and when α is 15 ° to 75 °, it exceeds 60,000 times and is more than four times the bending life of Comparative Example 2. It was. The copper foil of Comparative Example 1 corresponds to the copper foil disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2010-34541) and Patent Document 2 (Japanese Patent Laid-Open No. 2010-56128).
In Invention Example 1, the final rolling degree was matched with Comparative Example 1, and the rolling oil temperature was 25 ° C. The I / I 0 of this copper foil was 65, the same as in Comparative Example 1. On the other hand, the elongation in the 45 ° direction was about 5 times the elongation in the 0 ° and 90 ° directions, and the elongation at 45 ° was 33.8%, exceeding 20%. The bending life of Invention Example 1 was the same level as that of Comparative Example 1 when α was close to 0 ° and 90 °. However, when the ridge line of the bent portion was inclined with respect to the LD direction, the bending life was improved over that of Comparative Example 1. The bending life was about 20,000 times (30%) longer than Comparative Example 1.
（例２）
０．０１２〜０．０４５質量％のＡｇを含有するタフピッチ銅、または０．００５〜０．００８質量％のＳｎを含有する無酸素銅を成分とする厚さ９〜１２μｍの圧延銅箔を種々の最終圧延条件で製造した。それぞれの銅箔に対し、αを０°および３０°としてＦＰＣを製造し、その屈曲寿命を評価した。ＦＣＣＬの製造時の熱処理条件は３６０℃、６分間とした。評価結果を表２に示す。
発明例２〜１３では、最終圧延加工度を９３％以上、圧延油温度を２０〜３０℃としたため、熱処理後、４５°方向の伸びは０°および９０°方向の伸びに対し４倍以上となり、４５°の伸びが２０％を超えた。また、０°の屈曲寿命は、箔厚１８μｍで１万回以上、１２μｍで２万回以上、９μｍで１５万回以上であり、３０°の屈曲寿命は０°の屈曲寿命の２．３倍以上となった。
比較例３では加工度が９３％に満たなかったため、Ｉ／Ｉ0が２５未満であり、さらに４５°方向の伸びが０°および９０°方向の伸びに対し４倍未満であり、４５°方向の伸びが２０％未満である。０°の屈曲寿命は１．４万回と、発明例２〜５（加工度以外の条件が同じ）と比べて明らかに低く、３０°方向にＦＰＣを採取することで屈曲寿命が向上する傾向も認められない。
比較例４〜６では圧延油温度が３０℃を超えたため、４５°方向の伸びが０°および９０°方向の伸びに対し４倍未満となり、４５°方向の伸びが２０％未満となった。比較例４を発明例６、７と、比較例５を発明例１２と、比較例６を発明例１３とそれぞれ比較すると、０°の屈曲寿命は同等だが３０°の屈曲寿命が劣っている。
(Example 2)
Various rolled copper foils having a thickness of 9 to 12 μm composed of tough pitch copper containing 0.012 to 0.045 mass% Ag or oxygen-free copper containing 0.005 to 0.008 mass% Sn Produced under the final rolling conditions. FPC was manufactured with α being 0 ° and 30 ° for each copper foil, and the flex life was evaluated. The heat treatment conditions during the production of FCCL were 360 ° C. and 6 minutes. The evaluation results are shown in Table 2.
In Invention Examples 2 to 13, since the final rolling degree was 93% or more and the rolling oil temperature was 20 to 30 ° C., the 45 ° elongation after heat treatment was 4 times or more the 0 ° and 90 ° elongation. , 45 ° elongation exceeded 20%. The 0 ° bending life is 10,000 times or more at a foil thickness of 18 μm, 20,000 times or more at 12 μm, and 150,000 times or more at 9 μm. The bending life at 30 ° is 2.3 times the bending life at 0 °. That's it.
In Comparative Example 3, since the degree of processing was less than 93%, I / I 0 was less than 25, and the elongation in the 45 ° direction was less than 4 times the elongation in the 0 ° and 90 ° directions, and the 45 ° direction. Is less than 20%. The bending life at 0 ° is 14,000 times, which is clearly lower than those of Invention Examples 2 to 5 (the conditions other than the processing degree are the same), and the bending life tends to be improved by collecting FPC in the 30 ° direction. Is also not allowed.
In Comparative Examples 4 to 6, since the rolling oil temperature exceeded 30 ° C, the 45 ° elongation was less than 4 times the 0 ° and 90 ° elongation, and the 45 ° elongation was less than 20%. Comparing Comparative Example 4 with Inventive Examples 6 and 7, Comparative Example 5 with Inventive Example 12, and Comparative Example 6 with Inventive Example 13, the 0 ° bending life is equivalent, but the 30 ° bending life is inferior.
（例３）
熱処理条件が銅箔のＩ／Ｉ0および伸び特性に与える影響を検証する目的で、Ａｇを０．０１８質量％添加したタフピッチ銅（酸素濃度０．０２質量％）を成分とする、厚さ１２μｍの圧延銅箔を製造し、種々の条件で焼鈍後のＩ／Ｉ0および伸び特性を求めた。最終圧延では加工度を９９．２％、圧延油温度を２５℃とした。
表３に、熱処理工程における加熱温度Ｔ（℃）および加熱時間ｔ（ｈ）が、熱処理後のヤング率に及ぼす影響を示す。発明例１４〜２６は、（Ｔ＋２７３）×（１４＋ｌｏｇｔ）が６０００〜１００００に調整されたものであり、熱処理工程の条件が変更されても本発明が目的とするＩ／Ｉ0および伸びが得られていることが分かる。比較例７〜１０は（Ｔ＋２７３）×（１４＋ｌｏｇｔ）が６０００を下回るか１００００を超えるかしたものであるが、Ｉ／Ｉ0、伸び特性ともに本発明の規定から外れている。
(Example 3)
A thickness of 12 μm containing tough pitch copper (oxygen concentration 0.02% by mass) added with 0.018% by mass of Ag for the purpose of verifying the effect of heat treatment conditions on I / I 0 and elongation characteristics of the copper foil. A rolled copper foil was manufactured, and I / I 0 and elongation characteristics after annealing were determined under various conditions. In the final rolling, the working degree was 99.2% and the rolling oil temperature was 25 ° C.
Table 3 shows the influence of the heating temperature T (° C.) and the heating time t (h) in the heat treatment step on the Young's modulus after the heat treatment. Inventive Examples 14 to 26 were prepared by adjusting (T + 273) × (14 + logt) to 6000 to 10,000, and even if the conditions of the heat treatment process were changed, the intended I / I 0 and elongation were obtained. I understand that In Comparative Examples 7 to 10, (T + 273) × (14 + logt) is less than 6000 or more than 10,000, but both I / I 0 and elongation characteristics are outside the definition of the present invention.
１ 柔軟性樹脂基板
２ 配線
３ コネクタ端子
４ 片面ＦＰＣ
1 Flexible resin board 2 Wiring 3 Connector terminal 4 Single-sided FPC
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| CN209376018U (en) | 2018-11-14 | 2019-09-10 | 奥特斯(中国)有限公司 | Component load-bearing part with improved bending property |
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