JP5194602B2 - Method for producing metal-coated polyimide substrate - Google Patents
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Description
本発明は、金属被覆ポリイミド基板の製造方法に関し、さらに詳しくは、金属被覆ポリイミド基板を加熱する際の寸法変化のばらつきが低減され、ＣＯＦとして用いたとき、安定してボンディングを行なうことができ、かつ不良率を改善することができる金属被覆ポリイミド基板の製造方法に関する。 The present invention relates to a method for producing a metal-coated polyimide substrate, more specifically, variation in dimensional change when the metal-coated polyimide substrate is heated is reduced, and when used as a COF, stable bonding can be performed. And it is related with the manufacturing method of the metal-coated polyimide board which can improve a defect rate.
近年、金属被覆ポリイミド基板は、液晶画面に画像を表示するための駆動用半導体を実装する半導体実装用の基板として汎用されている。前記金属被覆ポリイミド基板に用いるポリイミドフィルムは、優れた耐熱性を有し、しかも機械的、電気的及び化学的特性においても他のプラスティック材料に比べ遜色のないことから、例えば、プリント配線板（ＰＷＢ）、フレキシブルプリント配線板（ＦＰＣ）、テープ自動ボンディング用テープ（ＴＡＢ）、チップオンフィルム（ＣＯＦ）等の電子部品用の絶縁基板材料として多用されている。このようなＰＷＢ、ＦＰＣ、ＴＡＢ、及びＣＯＦとしては、ポリイミドフィルムの少なくとも片面上に金属層を被覆した金属被膜ポリイミド基板を用いてこれを加工することによって得られている。 In recent years, a metal-coated polyimide substrate has been widely used as a semiconductor mounting substrate on which a driving semiconductor for displaying an image on a liquid crystal screen is mounted. The polyimide film used for the metal-coated polyimide substrate has excellent heat resistance and is inferior to other plastic materials in mechanical, electrical and chemical characteristics. For example, a printed wiring board (PWB) ), Flexible printed wiring boards (FPC), tapes for automatic tape bonding (TAB), chip-on-film (COF), etc., are widely used as insulating substrate materials for electronic components. Such PWB, FPC, TAB, and COF are obtained by processing a metal film polyimide substrate in which a metal layer is coated on at least one surface of a polyimide film.
この中で、特に、液晶画面表示用ドライバーＩＣチップを実装する手法として、ＣＯＦが注目されている。ＣＯＦは、従来の実装法であったＴＣＰ（Ｔａｐｅ Ｃａｒｒｉｅｒ Ｐａｃｋａｇｅ）に比べて、ファインピッチ実装が可能であり、ドライバーＩＣの小型化とコストダウンを図ることが容易な実装法である。このＣＯＦの製造方法としては、高耐熱、高絶縁性樹脂であるポリイミドフィルムと、一般的には、金属導電体として良導電体である銅層を密着させてなる金属被覆ポリイミド基板を使用し、その銅層をフォトリソグラフィー技法によってファインパターニングし、さらに所望の箇所にスズめっき及びソルダーレジストを被覆して得る方法が一般的である。 Of these, COF is attracting attention as a technique for mounting a driver IC chip for displaying a liquid crystal screen. The COF is a mounting method that enables fine pitch mounting compared to TCP (Tape Carrier Package), which is a conventional mounting method, and facilitates downsizing and cost reduction of the driver IC. As a method for producing this COF, a polyimide film that is a high heat resistance and high insulating resin and, in general, a metal-coated polyimide substrate formed by adhering a copper layer that is a good conductor as a metal conductor, In general, the copper layer is finely patterned by a photolithography technique, and a desired portion is coated with tin plating and a solder resist.
上記金属被覆ポリイミド基板を製造する際、ポリイミドフィルム表面に金属層を形成する方法としては、例えば、まず、スパッタリング法によりニッケル、クロム、ニッケルクロム合金等からなる金属シード層を形成し、その上に良導電性を付与するために銅層を形成して金属被膜を得る。さらに、通常は、回路形成のための導電層を厚膜化するため、電気めっき法、又は電気めっきと無電解めっきを併用する方法によって銅等の金属導電体を形成することが行われている。 When manufacturing the metal-coated polyimide substrate, as a method of forming a metal layer on the surface of the polyimide film, for example, first, a metal seed layer made of nickel, chromium, nickel-chromium alloy or the like is formed by sputtering, and then on it. In order to impart good conductivity, a copper layer is formed to obtain a metal film. Furthermore, in order to increase the thickness of the conductive layer for circuit formation, a metal conductor such as copper is usually formed by electroplating or a method using both electroplating and electroless plating. .
なお、上記スパッタリング法によって形成される金属被膜の厚さとしては、１００〜５００ｎｍが一般的である。また、金属導電体の厚さは、例えば、サブトラクティブ法によって回路を形成する場合には、５〜１２μmが一般的である。 In addition, as a thickness of the metal film formed by the said sputtering method, 100-500 nm is common. Further, the thickness of the metal conductor is generally 5 to 12 μm, for example, when a circuit is formed by a subtractive method.
ここで、電気めっき法によって金属導電体を形成する場合には、例えば、めっき液が供給され、槽内部にカソードの役割を担うめっき面と対向するように陽極を設置しためっき槽が少なくとも２槽である複数槽でフィルムの搬送方向に並べて設置され、各めっき槽に電力を供給する給電部とフィルム状基板を連続的に搬送させるための機構を有した連続めっき装置が用いられる。例えば、陽極及び電解液を有するめっき槽を複数配置し、厚さ３μｍ以下の金属被膜を有する絶縁体フィルムを、これらのめっき槽に順次連続的に供給し、各めっき槽毎に通電量を制御し、各めっき槽における通電量を、該フィルムが供給される順にしたがって順次増加させ、均一に良好なで電気めっき被膜を連続的に形成する連続めっき方法（例えば、特許文献１参照。）が開示されている。 Here, when the metal conductor is formed by the electroplating method, for example, at least two plating tanks in which the plating solution is supplied and the anode is disposed so as to face the plating surface serving as the cathode inside the tank are provided. A continuous plating apparatus that is installed in a plurality of tanks in the film transport direction and has a mechanism for continuously transporting the power supply unit that supplies power to each plating tank and the film-like substrate is used. For example, a plurality of plating tanks having an anode and an electrolytic solution are arranged, and an insulator film having a metal film with a thickness of 3 μm or less is successively supplied to these plating tanks, and the energization amount is controlled for each plating tank. Then, a continuous plating method (see, for example, Patent Document 1) in which the energization amount in each plating tank is sequentially increased in the order in which the films are supplied, and the electroplating film is continuously formed uniformly and satisfactorily. Has been.
上記のようなスパッタリング法及びめっき法によって金属層が形成された金属被覆ポリイミド基板は、金属層の薄膜化が容易であり、かつ、ポリイミドフィルムと金属被膜の界面を平滑に維持しながら十分な密着強度を得る技術が確立されているため、これを用いて得られるＣＯＦは、回路のファインピッチ化に適している。そのため、インナーリード部で２５〜３０μmピッチを有するＣＯＦの量産が開始され、続いて２０μmピッチ以下の狭ピッチＣＯＦの開発が進んでいる。 The metal-coated polyimide substrate on which the metal layer is formed by the sputtering method and the plating method as described above is easy to reduce the thickness of the metal layer, and has sufficient adhesion while maintaining a smooth interface between the polyimide film and the metal film. Since a technique for obtaining strength has been established, the COF obtained by using this is suitable for fine pitch circuits. For this reason, mass production of COF having a pitch of 25 to 30 μm at the inner lead portion has been started, and development of a narrow pitch COF having a pitch of 20 μm or less is proceeding.
ところで、ＣＯＦでは、半導体チップをインナーリードボンディングによって搭載し、その後アウターリードボンディングによって液晶パネルに実装される。一般に、ボンディングの際に付加する熱によってＣＯＦが寸法変化するため、予めその変化量を予測し、前もってＣＯＦに形成された回路、特にインナーリードの間隔とアウターリードの間隔に補正を加えることが行われる。特に、２０μmピッチのＣＯＦでは、狭ピッチであるため、リード間隔の厳密な補正が必要となっていた。 By the way, in COF, a semiconductor chip is mounted by inner lead bonding, and then mounted on a liquid crystal panel by outer lead bonding. In general, since the COF changes in size due to heat applied during bonding, the amount of change is predicted in advance, and correction is made to the circuits formed in the COF in advance, particularly the interval between the inner leads and the interval between the outer leads. Is called. In particular, a COF with a pitch of 20 μm has a narrow pitch, so that a strict correction of the lead interval is required.
しかしながら、上記のようなスパッタリング法及びめっき法によって金属層が形成された金属被覆ポリイミド基板を使用した場合においても、２０μmピッチのＣＯＦでは、ボンディングの際に端部のリードが所望のボンディング位置を外れる比率が増加して不良率が高くなるという問題があった。これは、金属被覆ポリイミド基板を加熱する際の寸法変化のばらつきが、主たる原因と思われる。このような状況から、加熱する際の寸法変化のばらつきをさらに低減することができる金属被覆ポリイミド基板が求められている。 However, even when a metal-coated polyimide substrate on which a metal layer is formed by the sputtering method and the plating method as described above is used, with a COF of 20 μm pitch, the end leads deviate from the desired bonding position during bonding. There has been a problem that the defect rate increases as the ratio increases. This seems to be mainly due to variations in dimensional changes when the metal-coated polyimide substrate is heated. Under such circumstances, there is a demand for a metal-coated polyimide substrate that can further reduce variation in dimensional change during heating.
本発明の目的は、上記の従来技術の問題点に鑑み、金属被覆ポリイミド基板を加熱する際の寸法変化のばらつきが低減され、ＣＯＦとして用いたとき、安定してボンディングを行なうことができ、かつ不良率を改善することができる金属被覆ポリイミド基板の製造方法を提供することにある。 In view of the above-mentioned problems of the prior art, the object of the present invention is to reduce variation in dimensional change when heating a metal-coated polyimide substrate, and when used as a COF, can stably perform bonding, and An object of the present invention is to provide a method for producing a metal-coated polyimide substrate capable of improving the defect rate.
本発明者らは、上記目的を達成するために、金属被覆ポリイミド基板の製造方法について、鋭意研究を重ねた結果、ポリイミドフィルムの表面に金属被膜を形成するスパッタリング工程、及び得られたポリイミドフィルムの金属被膜上に、連続めっき装置を用いて、金属導電体を形成する電気めっき工程を含む金属被覆ポリイミド基板の製造方法において、前記スパッタリング工程において、特定の表面抵抗を有する金属被膜を形成して、スパッタリングでの熱履歴のばらつきを抑制し、かつ後続の電気めっきの際の陰極電流密度差を低減し、また、前記電気めっき工程において、特定の陰極電流密度に制御して、電流密度分布を均一化するとともに、特定のフィルム搬送速度に調整して、積層構造の界面が酸化されるのを抑制したところ、得られた金属被覆ポリイミド基板は、金属層の残留応力のばらつきが低減され、これを加熱する際の寸法変化のばらつきが低減され、ＣＯＦとして用いたとき、安定してボンディングを行なうことができ、かつ不良率を改善することができることを見出し、本発明を完成した。 In order to achieve the above object, the present inventors have conducted extensive research on a method for producing a metal-coated polyimide substrate. As a result, a sputtering process for forming a metal film on the surface of the polyimide film, and the obtained polyimide film In the method of manufacturing a metal-coated polyimide substrate including an electroplating step of forming a metal conductor using a continuous plating apparatus on the metal coating, in the sputtering step, a metal coating having a specific surface resistance is formed, Suppresses variations in thermal history during sputtering and reduces the difference in cathode current density during subsequent electroplating, and controls the cathode current density to a specific value in the electroplating process to make the current density distribution uniform. And adjusting to a specific film transport speed to suppress the oxidation of the interface of the laminated structure, The resulting metal-coated polyimide substrate has reduced variations in residual stress of the metal layer, reduced variations in dimensional change when heating the metal layer, can be stably bonded when used as a COF, and The present inventors have found that the defect rate can be improved and completed the present invention.
すなわち、本発明の第１の発明によれば、ポリイミドフィルムの表面に銅層を有する金属被膜を形成するスパッタリング工程、及び得られたポリイミドフィルムの金属被膜上に、フィルムの搬送と金属被膜への給電を行うローラーと該金属被膜と対向させた陽極を備えた少なくとも２槽のめっき槽からなる連続めっき装置を用いて、金属導電体を形成する電気めっき工程を含む金属被覆ポリイミド基板の製造方法であって、
下記の（１）及び（２）の要件を満足することを特徴とする金属被覆ポリイミド基板の製造方法が提供される。
（１）前記スパッタリング工程において、形成する金属被膜の表面抵抗を、０．１〜１．０Ω／□に制御し、かつ、銅層の厚さを５０〜５００ｎｍに制御する。
（２）前記電気めっき工程において、陰極電流密度は、全めっき槽の平均陰極電流密度を１〜３Ａ／ｄｍ２に、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を２〜５に制御するとともに、フィルムの搬送速度は、８０〜１５０ｍ／ｈに調整する。
That is, according to the first invention of the present invention, the sputtering process for forming a metal film having a copper layer on the surface of the polyimide film, and the transportation of the film and the metal film on the metal film of the obtained polyimide film A method for producing a metal-coated polyimide substrate comprising an electroplating step of forming a metal conductor using a continuous plating apparatus comprising at least two plating tanks provided with a roller for supplying power and an anode opposed to the metal coating. There,
Provided is a method for producing a metal-coated polyimide substrate, which satisfies the following requirements (1) and (2).
(1) In the sputtering step, the surface resistance of the metal film to be formed is controlled to 0.1 to 1.0 Ω / □ , and the thickness of the copper layer is controlled to 50 to 500 nm .
(2) In the electroplating step, the cathode current density is determined by setting the average cathode current density of all plating tanks to 1 to 3 A / dm 2 and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank. While controlling to 2-5, the conveyance speed of a film is adjusted to 80-150 m / h.
また、本発明の第２の発明によれば、第１の発明において、前記陽極は、不溶性陽極であることを特徴とする金属被覆ポリイミド基板の製造方法が提供される。 According to a second aspect of the present invention, there is provided the method for producing a metal-coated polyimide substrate according to the first aspect, wherein the anode is an insoluble anode.
また、本発明の第３の発明によれば、第２の発明において、前記陰極電流密度は、全めっき槽の平均陰極電流密度が１．５〜３Ａ／ｄｍ２であり、各めっき槽内での陰極電流密度の最小値に対する最大値の比が２〜３であり、及びフィルムの搬送速度は、１００〜１５０ｍ／ｈであることを特徴とする金属被覆ポリイミド基板の製造方法が提供される。 According to the third invention of the present invention, in the second invention, the cathode current density is 1.5 to 3 A / dm2 in average plating current density of all plating tanks, A method for producing a metal-coated polyimide substrate is provided, wherein the ratio of the maximum value to the minimum value of the cathode current density is 2 to 3, and the film conveyance speed is 100 to 150 m 2 / h.
また、本発明の第４の発明によれば、第１〜３いずれかの発明において、前記金属被膜は、金属シード層とその表面上に形成された銅層からなることを特徴とする金属被覆ポリイミド基板の製造方法が提供される。 According to a fourth aspect of the present invention, in any one of the first to third aspects, the metal coating comprises a metal seed layer and a copper layer formed on the surface thereof. A method for manufacturing a polyimide substrate is provided.
また、本発明の第５の発明によれば、第１〜４いずれかの発明において、前記金属導電体は、銅であることを特徴とする金属被覆ポリイミド基板の製造方法が提供される。 According to a fifth aspect of the present invention, there is provided the method for producing a metal-coated polyimide substrate according to any one of the first to fourth aspects, wherein the metal conductor is copper.
本発明の金属被覆ポリイミド基板の製造方法によれば、得られる金属被覆ポリイミド基板を加熱する際の寸法変化のばらつきが低減され、これをＣＯＦとして用いたとき、安定してボンディングを行なうことができ、かつ不良率を改善することができる。特に、開発中の２０μmピッチに代表される狭ピッチＣＯＦに用いた場合には、ボンディングの際に端部のリードが所望のボンディング位置を外れる比率が減少して不良率が大幅に改善されるので、その工業的価値は極めて大きい。 According to the method for producing a metal-coated polyimide substrate of the present invention, variation in dimensional change when the resulting metal-coated polyimide substrate is heated is reduced, and when this is used as a COF, bonding can be performed stably. In addition, the defect rate can be improved. In particular, when used in a narrow pitch COF represented by a 20 μm pitch under development, the rate at which the end leads are out of the desired bonding position during bonding is reduced and the defect rate is greatly improved. The industrial value is extremely large.
以下、本発明の金属被覆ポリイミド基板の製造方法を詳細に説明する。
本発明の金属被覆ポリイミド基板の製造方法は、ポリイミドフィルムの表面に金属被膜を形成するスパッタリング工程、及び得られたポリイミドフィルムの金属被膜上に、フィルムの搬送と金属被膜への給電を行うローラーと該金属被膜と対向させた陽極を備えた少なくとも２槽のめっき槽からなる連続めっき装置を用いて、金属導電体を形成する電気めっき工程を含む金属被覆ポリイミド基板の製造方法であって、
下記の（１）及び（２）の要件を満足することを特徴とする。
（１）前記スパッタリング工程において、形成する金属被膜の表面抵抗を、０．１〜１．０Ω／□に制御する。
（２）前記電気めっき工程において、陰極電流密度は、全めっき槽の平均陰極電流密度を１〜３Ａ／ｄｍ２に、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を１〜５に制御するとともに、フィルムの搬送速度は、８０〜３００ｍ／ｈに調整する。
Hereinafter, the manufacturing method of the metal-coated polyimide substrate of the present invention will be described in detail.
The manufacturing method of the metal-coated polyimide substrate of the present invention includes a sputtering process for forming a metal film on the surface of the polyimide film, and a roller for feeding the film and supplying power to the metal film on the metal film of the obtained polyimide film. A method for producing a metal-coated polyimide substrate comprising an electroplating step of forming a metal conductor using a continuous plating apparatus comprising at least two plating tanks provided with an anode opposed to the metal coating,
It satisfies the following requirements (1) and (2).
(1) In the sputtering step, the surface resistance of the metal film to be formed is controlled to 0.1 to 1.0Ω / □.
(2) In the electroplating step, the cathode current density is determined by setting the average cathode current density of all plating tanks to 1 to 3 A / dm 2 and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank. While controlling to 1-5, the conveyance speed of a film is adjusted to 80-300 m / h.
本発明の製造方法において、上記の（１）及び（２）の要件を満足するように、スパッタリング工程及び電気めっき工程を行い、形成する金属被膜の表面抵抗を制御するとともに、電気めっきの平均陰極電流密度を一定の範囲とすることにより、積層構造の層毎の電流密度差を小さくして、形成する金属層の残留応力のばらつきを低減し、さらに給電のためのめっきの中断時間を低減して、積層構造の界面が酸化されるのを抑制することが重要である。これによって、加熱する際の寸法変化のばらつきが低減され、ＣＯＦとして用いたとき、安定してボンディングを行なうことができる金属被覆ポリイミド基板が得られる。 In the production method of the present invention, a sputtering process and an electroplating process are performed so as to satisfy the requirements (1) and (2) above, and the surface resistance of the metal film to be formed is controlled, and the average cathode for electroplating By setting the current density within a certain range, the difference in current density between layers of the laminated structure is reduced, the variation in residual stress of the metal layer to be formed is reduced, and the interruption time of plating for power supply is further reduced. Therefore, it is important to suppress oxidation of the interface of the laminated structure. As a result, variation in dimensional change during heating is reduced, and a metal-coated polyimide substrate that can be bonded stably when used as a COF is obtained.
以下に、スパッタリング工程及び電気めっき工程で形成する金属層の残留応力のばらつきについて、従来法の問題点とともに、本発明の製造方法での作用について、詳細に説明する。
すなわち、一般に、金属被覆ポリイミド基板を用いてＣＯＦのリードを形成する際には、前述したようにリード形成時に加わる熱履歴等を加味して、フォトレジスト露光用マスクに形成されたパターン寸法に一定の補正を行う。これは、ＩＣチップとの接合時及び液晶パネルとの接合時までに加わる熱履歴等によりリード間隔が変化する量をあらかじめ予測し、剥離を防止するために行うものである。
Below, the dispersion | variation in the residual stress of the metal layer formed in a sputtering process and an electroplating process is demonstrated in detail about the effect | action by the manufacturing method of this invention with the problem of a conventional method.
That is, in general, when forming a COF lead using a metal-coated polyimide substrate, the pattern size formed on the photoresist exposure mask is constant taking into account the thermal history applied during lead formation as described above. Perform the correction. This is performed in order to prevent the separation by predicting in advance the amount of change in the lead interval due to the thermal history or the like applied before bonding to the IC chip and to the liquid crystal panel.
なお、リード間隔が変化する要因としては、ポリイミドフィルム、金属層、及びソルダーレジスト等のＣＯＦ構成部材の熱膨張、熱収縮等に起因する変形によるものである。これら熱による変形は、当然生じる現象であり、この変形量は、試験的にあらかじめ把握することができるものである。ところが、問題となるのは、この変形量が一定しないこと、すなわち、ばらつくことであり、しかも、この変形量のばらつきが大きく、かつリード間隔がファインピッチになるほど、前記剥離の危険性が高まることである。これらＣＯＦ構成部材のばらつき発生原因としては、ポリイミドフィルムに関しては、成膜時の熱履歴、延伸のばらつき、及びフィルムの厚さのばらつきが主要因であり、また、ソルダーレジストに関しては、厚さのばらつきが主要因である。一方、金属層に関しては、厚さのばらつきも主要因であるが、金属層の残留応力のばらつきによっても大きな影響を受ける。 The reason why the lead interval changes is due to deformation caused by thermal expansion, thermal contraction, etc. of the COF constituent members such as polyimide film, metal layer, and solder resist. Such deformation due to heat is a phenomenon that naturally occurs, and the amount of deformation can be preliminarily grasped experimentally. However, the problem is that the amount of deformation is not constant, that is, it varies, and the greater the variation in the amount of deformation and the finer the lead interval, the greater the risk of peeling. It is. As for the cause of the variation of these COF constituent members, regarding the polyimide film, the thermal history at the time of film formation, the variation in stretching, and the variation in the thickness of the film are the main factors, and regarding the solder resist, Variation is the main factor. On the other hand, regarding the metal layer, the thickness variation is also a main factor, but it is also greatly influenced by the residual stress variation of the metal layer.
この中で、金属層を構成する金属導電体を形成する電気めっきの際に、めっき膜中に残留する応力のばらつきの要因としては、ポリイミドフィルム上に形成された陰極の電流密度（以下、陰極電流密度と呼称する。）の変化量が最も大きな影響を有する。すなわち、電気めっき法によって、ポリイミドフィルム表面にスパッタリングにより形成した金属被膜上に金属導電体を形成する場合、一般に、電気めっきの初期段階においては、該金属被膜とその上に形成されるめっき膜が薄いため電気抵抗が高いので、めっき槽の電流密度を極めて低くせざるを得ない。その後、ある程度のめっき厚さまで成長した段階では、生産性と経済性を重視して、めっき槽の電流密度を急激に増加させる方法がとられていた。例えば、従来法では、各めっき槽を経て形成される積層構造のめっき膜は、スパッタリングにより形成した金属被膜の直上層では、０．００１〜０．０１Ａ／ｄｍ２の電流密度で、最表面層では、０．５〜１．０Ａ／ｄｍ２の電流密度で形成されていた。このときの全めっき槽の平均電流密度としては、０．３〜０．７Ａ／ｄｍ２である。一般に、めっき膜の残留応力は、陰極電流密度に比例し、電流密度が高いと応力も増大する傾向にある。このため、従来法では、上記のように広範な電流密度によって積層構造に形成されためっき膜の層毎の残留応力差は著しく大きくなり、これが寸法変化のばらつきの要因となっていた。 Among them, the current density of the cathode formed on the polyimide film (hereinafter referred to as the “cathode”) is a cause of the variation in the stress remaining in the plating film during the electroplating for forming the metal conductor constituting the metal layer. The amount of change in current density has the greatest influence. That is, when a metal conductor is formed on a metal film formed by sputtering on the polyimide film surface by electroplating, generally, in the initial stage of electroplating, the metal film and the plating film formed thereon are Since the electrical resistance is high because it is thin, the current density of the plating tank must be extremely low. After that, at the stage of growing to a certain plating thickness, a method was adopted in which the current density of the plating tank was rapidly increased with emphasis on productivity and economy. For example, in the conventional method, the plating film having a laminated structure formed through each plating tank has a current density of 0.001 to 0.01 A / dm 2 at the uppermost layer of the metal film formed by sputtering, and the outermost surface layer. Then, it was formed at a current density of 0.5 to 1.0 A / dm 2 . The average current density of the entire plating bath at this time, a 0.3~0.7A / dm 2. Generally, the residual stress of the plating film is proportional to the cathode current density, and the stress tends to increase as the current density increases. For this reason, in the conventional method, the residual stress difference between the layers of the plating film formed in the laminated structure with a wide current density as described above becomes remarkably large, which causes variation in dimensional change.
このめっき膜の層毎の残留応力差を抑制する手段としては、電気めっきの初期段階の極めて低い電流密度のままで、めっきを継続することが考えられるが、生産性に著しい支障をきたすか、極めて長尺な生産ラインを構える必要があり現実的でない。例えば、平均電流密度０．１Ａ／ｄｍ２で、厚さ８μmまでめっきした場合、めっき時間は５時間程度が必要となる。また、極めて低電流密度でのめっきは残留応力の軽減には効果があるものの、その他の重要なめっき膜の物性である、伸び率、抗張力、耐折れ性等に影響を及ぼすため、現行のＣＯＦを使用した組み立て工程では、ボンディング以外のトラブルを発生させる危険性が高まることが考えられる。また、低電流密度で得られためっき膜では、耐折れ性が悪化するため、ＣＯＦのボンディングの際にリード断線等の危険性が増加する。さらに、経済性の点でも平均電流密度はある値以上を確保する必要がある。 As a means of suppressing the residual stress difference between the layers of this plating film, it is conceivable to continue the plating while maintaining an extremely low current density in the initial stage of electroplating. It is impractical to have a very long production line. For example, when plating is performed up to a thickness of 8 μm at an average current density of 0.1 A / dm 2 , a plating time of about 5 hours is required. In addition, although plating at an extremely low current density is effective in reducing residual stress, it affects the physical properties of other important plating films, such as elongation, tensile strength, and bending resistance. In the assembly process using, it is considered that the risk of generating troubles other than bonding is increased. In addition, the plating film obtained at a low current density deteriorates the bending resistance, so that the risk of a lead disconnection or the like increases during COF bonding. Furthermore, it is necessary to ensure an average current density of a certain value or more in view of economy.
これに対して、本発明の金属被覆ポリイミド基板の製造方法においては、前述のように、上記の（１）及び（２）の要件を満足するようにスパッタリング工程及び電気めっき工程を行い、形成する金属被膜の表面抵抗を制御するとともに、電気めっきの平均陰極電流密度を一定の範囲とすることにより、積層構造の層毎の電流密度差を小さくして、形成する金属層の残留応力のばらつきを低減し、さらに給電のためのめっきの中断時間を低減して、積層構造の界面が酸化されるのを抑制する。これにより、生産性を向上させるものである。 On the other hand, in the manufacturing method of the metal-coated polyimide substrate of the present invention, as described above, the sputtering process and the electroplating process are performed so as to satisfy the requirements (1) and (2). By controlling the surface resistance of the metal coating and keeping the average cathode current density of electroplating within a certain range, the difference in current density of each layer of the laminated structure is reduced, and the variation in residual stress of the metal layer to be formed is reduced. In addition, the interruption time of plating for power feeding is further reduced, and the interface of the laminated structure is prevented from being oxidized. Thereby, productivity is improved.
本発明の金属被覆ポリイミド基板の製造方法としては、ポリイミドフィルムの表面に金属被膜を形成するスパッタリング工程と得られたポリイミドフィルムの金属被膜上に、金属導電体を形成する電気めっき工程を含む。すなわち、ポリイミドフィルム表面に極めて薄い金属被膜を形成し、電気めっき法により所定の厚みまで厚付けするものである。 The method for producing a metal-coated polyimide substrate of the present invention includes a sputtering process for forming a metal film on the surface of the polyimide film and an electroplating process for forming a metal conductor on the metal film of the obtained polyimide film. That is, an extremely thin metal film is formed on the surface of the polyimide film and thickened to a predetermined thickness by electroplating.
１．スパッタリング工程
上記スパッタリング工程としては、上記の（１）の要件を除いては、特に限定されるものではなく、ポリイミドフィルムの表面に所望の厚さに金属被膜を形成する通常の金属被覆ポリイミド基板の製造方法に用いられる条件で行われる。ここで、上記スパッタリングに用いる装置としては、特に限定されるものではなく、金属被膜を構成する元素を含む所定の組成からなるターゲットを備えたマグネトロンスパッタ装置等が使用される。
1. Sputtering Step The sputtering step is not particularly limited except for the above requirement (1), and a normal metal-coated polyimide substrate that forms a metal film with a desired thickness on the surface of the polyimide film. It is performed under the conditions used in the manufacturing method. Here, the apparatus used for the sputtering is not particularly limited, and a magnetron sputtering apparatus provided with a target having a predetermined composition containing an element constituting the metal film is used.
上記製造方法に用いるポリイミドフィルムとしては、特に限定されるものではなく、Ｋａｐｔｏｎ ＥＮ（東レ・デュポン製）、Ｕｐｉｌｅｘ Ｓ（宇部興産製）、Ａｐｉｃａｌ（カネカ製）などの市販のポリイミドフィルムが用いられる。また、ポリイミドフィルムの厚さとしては、特に限定されるものではないが、屈曲げ性の確保を考慮すると、２５〜５０μmであることが好ましい。 It does not specifically limit as a polyimide film used for the said manufacturing method, Commercially available polyimide films, such as Kapton EN (made by Toray DuPont), Upilex S (made by Ube Industries), Apical (made by Kaneka), are used. In addition, the thickness of the polyimide film is not particularly limited, but is preferably 25 to 50 μm in consideration of securing the bendability.
上記スパッタリングで形成される金属被膜としては、特に限定されるものではないが、ポリイミドとの密着力とその耐熱性等の信頼性を確保するために、金属シード層として、ニッケル、クロム、モリブデン等の金属、或いはニッケルクロム合金等のこれらの合金から選定されるが、クロムを全量に対し５〜３０質量％含有するニッケルクロム合金が好ましい。また、その厚さは、５〜５０ｎｍが好ましい。すなわち、ＣＯＦ等に用いて金属層をエッチングすることによって電子回路を形成する場合には、良導電体である銅とエッチング性が大幅に異なるような合金組成及び厚さでは不都合であるからである。 The metal film formed by the sputtering is not particularly limited, but as a metal seed layer, nickel, chromium, molybdenum, etc. are used in order to ensure reliability such as adhesion to polyimide and heat resistance. However, a nickel chromium alloy containing 5 to 30% by mass of chromium with respect to the total amount is preferable. The thickness is preferably 5 to 50 nm. That is, when an electronic circuit is formed by etching a metal layer using COF or the like, it is inconvenient if the alloy composition and thickness are significantly different from those of copper as a good conductor. .
さらに、電気めっきを施す前に導電性を確保するため表面抵抗を低減させるため、上記金属被膜表面に引き続き銅層をスパッタリングによって形成することが好ましい。この際の銅層としては、表面抵抗を（１）の要件を満足する所定値になるように制御する。すなわち、厚さが５０ｎｍ未満では十分な導電性が得られず、その後の電気めっきによる銅の析出の均一性に悪影響を及ぼす。一方、厚さが５００ｎｍを超えると、導電性を付与する点では好都合であるが、スパッタリングによるポリイミドフィルムへの熱履歴が高まることによる基板の寸法変化、変形等の影響によって、ＣＯＦ等の得られる製品への悪影響が懸念される。 Furthermore, in order to reduce surface resistance in order to ensure conductivity before electroplating, it is preferable to form a copper layer on the surface of the metal film by sputtering. In this case, the surface resistance of the copper layer is controlled to a predetermined value that satisfies the requirement (1). That is, if the thickness is less than 50 nm, sufficient conductivity cannot be obtained, and the uniformity of copper deposition by subsequent electroplating is adversely affected. On the other hand, if the thickness exceeds 500 nm, it is advantageous in terms of imparting conductivity, but COF and the like can be obtained due to the influence of dimensional change, deformation, etc. of the substrate due to an increase in the thermal history of the polyimide film by sputtering. There are concerns about adverse effects on the product.
上記製造方法に係る（１）の要件は、前記スパッタリング工程において、形成する金属被膜の表面抵抗を、０．１〜１．０Ω／□に制御することである。すなわち、スパッタリングで形成する金属被膜の表面抵抗を低下させることによって、電気めっきの初期段階から電流密度を向上させることができるので、平均陰極電流密度を向上することができる。ところで、前記金属被膜の表面抵抗を低下させるということは、すなわち前記金属被膜の厚さを増加させるということであり、この場合、スパッタリングでポリイミドフィルムに付加される熱量が増加することになり、当然ばらつきも大きくなる。その結果、ＣＯＦのボンディングの際のリード位置ずれの危険性が増加する。したがって、本発明の製造方法では、前記金属被膜の表面抵抗は、スパッタリングで付加される熱量の増加によるばらつきが大きくならない範囲が選ばれる。 The requirement (1) relating to the above production method is to control the surface resistance of the metal film to be formed to 0.1 to 1.0Ω / □ in the sputtering step. That is, since the current density can be improved from the initial stage of electroplating by reducing the surface resistance of the metal film formed by sputtering, the average cathode current density can be improved. By the way, reducing the surface resistance of the metal film means that the thickness of the metal film is increased, and in this case, the amount of heat applied to the polyimide film by sputtering is naturally increased. Variations also increase. As a result, there is an increased risk of lead misalignment during COF bonding. Therefore, in the manufacturing method of the present invention, the surface resistance of the metal film is selected within a range in which variation due to an increase in the amount of heat applied by sputtering does not increase.
すなわち、金属被膜の表面抵抗が０．１Ω／□未満では、スパッタリングの熱履歴のばらつきが大きくなり、ボンディングの際の位置ずれが増加する。一方、金属被膜の表面抵抗が１．０Ω／□を超えると、電気めっきの初期段階において、陰極電流密度を極端に低く抑えることが必要であり、めっきの積層構造の層毎の陰極電流密度差が大きくなってしまう。或いは、１．０Ω／□を超えた状態で無理に陰極電流密度を大きくすると、めっき膜の残留応力が大きくなってしまう。さらに、スパッタリングの熱履歴のばらつきを小さく、かつ陰極電流密度差を小さくするためには、金属被膜の表面抵抗を、０．２〜０．８Ω／□に制御することが好ましい。 That is, when the surface resistance of the metal coating is less than 0.1 Ω / □, the variation in the thermal history of sputtering increases, and the positional deviation during bonding increases. On the other hand, if the surface resistance of the metal coating exceeds 1.0 Ω / □, it is necessary to keep the cathode current density extremely low in the initial stage of electroplating, and the difference in cathode current density between layers of the laminated structure of plating Will become bigger. Alternatively, if the cathode current density is forcibly increased in a state exceeding 1.0Ω / □, the residual stress of the plating film increases. Furthermore, it is preferable to control the surface resistance of the metal coating to 0.2 to 0.8 Ω / □ in order to reduce the variation in the thermal history of sputtering and to reduce the difference in cathode current density.
上記金属被膜の表面抵抗の制御方法としては、その表面抵抗が、スパッタリングで形成される金属被膜の厚さ、純度、結晶子径等によって影響を受けるので、所望の表面抵抗が得られるように、スパッタリング条件を選定することにより行う。例えば、真空雰囲気中で行われるマグネトロンスパッタリングで、銅層をスパッタリングで形成する場合には、銅層の厚さを３００〜１０ｎmとすることにより、金属被膜の表面抵抗を０．１〜１．０Ω／□とすることができる。 As a method for controlling the surface resistance of the metal film, the surface resistance is affected by the thickness, purity, crystallite diameter, etc. of the metal film formed by sputtering, so that a desired surface resistance can be obtained. This is done by selecting the sputtering conditions. For example, when the copper layer is formed by sputtering in magnetron sputtering performed in a vacuum atmosphere, the surface resistance of the metal film is 0.1 to 1.0Ω by setting the thickness of the copper layer to 300 to 10 nm. / □.
２．電気めっき工程
上記電気めっき工程としては、上記の（２）の要件を除いては、特に限定されるものではなく、ポリイミドフィルム上に形成された（１）の要件を満足する金属被膜上に、連続めっき装置を用いて、金属導電体を形成する通常の金属被覆ポリイミド基板の製造方法に用いられる条件で行われる。
なお、前記連続めっき装置は、フィルムの搬送と金属被膜への給電を行うローラーと、該金属被膜と対向させた陽極を備えた少なくとも２槽のめっき槽からなるものであり、例えば、通常、設置スペースを大幅に節約できることから、竪型のめっき槽をめっきする厚さ等に応じて設定される必要数を搬送ライン方向に並べて配置したものが使用される。ここで、金属被膜を有する一定幅のポリイミドフィルムを、めっき槽に一定の速度で順次連続的に供給し、金属被膜上に連続的にめっき層を形成する。すなわち、金属被膜と接触させて給電することができる導電性を有するローラーと、該金属被膜と対向する位置に設けた陽極とを設置しためっき槽と、フィルムを該めっき槽内に供給するめっき液と接触させながら搬送するフィルム搬送機構を備えた通常の金属被覆ポリイミド基板の製造方法に用いられる連続めっき装置が用いられる。
2. Electroplating step The electroplating step is not particularly limited except for the above requirement (2). On the metal film satisfying the requirement (1) formed on the polyimide film, Using a continuous plating apparatus, it is carried out under the conditions used in a normal method for producing a metal-coated polyimide substrate for forming a metal conductor.
The continuous plating apparatus is composed of at least two plating tanks equipped with a roller for feeding the film and supplying power to the metal coating, and an anode facing the metal coating. Since the space can be greatly saved, the required number set according to the thickness or the like for plating the vertical plating tank is arranged side by side in the conveyance line direction. Here, a fixed-width polyimide film having a metal coating is successively and continuously supplied to the plating tank at a constant speed to continuously form a plating layer on the metal coating. That is, a plating tank provided with a conductive roller capable of supplying power while being in contact with the metal film, an anode provided at a position facing the metal film, and a plating solution for supplying the film into the plating tank The continuous plating apparatus used for the manufacturing method of the normal metal-coated polyimide substrate provided with the film conveyance mechanism conveyed while making it contact with is used.
上記金属導電体としては、特に限定されるものではなく、ＣＯＦ等において回路材料として好ましく、かつ電気めっきによって被覆される導電性に優れた金属又は合金が用いられるが、銅が好ましい。このとき用いるめっき液としては、一般的な電気銅めっきに使用される市販の硫酸銅めっき浴を用いることができる。 The metal conductor is not particularly limited, and a metal or alloy excellent in conductivity that is preferable as a circuit material in COF or the like and is coated by electroplating is used, but copper is preferable. As a plating solution used at this time, a commercially available copper sulfate plating bath used for general electrolytic copper plating can be used.
上記製造方法に係る（２）の要件は、前記電気めっき工程において、陰極電流密度は、全めっき槽の平均陰極電流密度を１〜３Ａ／ｄｍ２に、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を１〜５に制御するとともに、フィルムの搬送速度は、８０〜３００ｍ／ｈに調整することである。すなわち、（１）の要件を満足する金属被膜上に形成される金属層の残留応力のばらつきを低減し、ボンディングの際の位置ずれを抑制するために、積層構造の層毎の電流密度差が小さくなるように、電気めっきの各層の平均陰極電流密度を一定の範囲とするものである。ところで、電気めっきの平均陰極電流密度としては、ボンディングの際の位置ずれを抑制する上では、積層構造の層毎の陰極電流密度差を小さくすればよいが、耐折れ曲げ性の確保、および生産性、経済性の点を考慮して、本発明の製造方法の電気めっき工程において、上記（２）の要件を用いる。 The requirement (2) relating to the manufacturing method is that, in the electroplating step, the cathode current density is an average cathode current density of all plating tanks of 1 to 3 A / dm 2 , and a cathode current density in each plating tank. The ratio of the maximum value to the minimum value is controlled to 1 to 5 and the film conveyance speed is adjusted to 80 to 300 m / h. That is, in order to reduce the variation in residual stress of the metal layer formed on the metal film that satisfies the requirement (1) and suppress the positional deviation during bonding, the current density difference between the layers of the laminated structure is The average cathode current density of each layer of electroplating is set within a certain range so as to decrease. By the way, as for the average cathode current density of electroplating, in order to suppress misalignment during bonding, the difference in cathode current density for each layer of the laminated structure may be reduced. Considering the point of the property and economy, the requirements of said (2) are used in the electroplating process of the manufacturing method of this invention.
すなわち、陰極電流密度として、全めっき槽の平均陰極電流密度が１Ａ／ｄｍ２未満では、折れ曲げ性を確保することが困難となる。一方、平均陰極電流密度が３Ａ／ｄｍ２を超えると、残留応力のばらつきを抑制することが困難になる。さらに、信頼性及び経済性を確保する上では、全めっき槽の平均陰極電流密度は、１．５〜３Ａ／ｄｍ２とすることが好ましい。 That is, if the average cathode current density of all plating tanks is less than 1 A / dm 2 as the cathode current density, it becomes difficult to ensure the bendability. On the other hand, when the average cathode current density exceeds 3 A / dm 2 , it becomes difficult to suppress variation in residual stress. Furthermore, in order to ensure the reliability and economic efficiency, the average cathode current density of the entire plating bath is preferably set to 1.5~3A / dm 2.
また、各めっき槽内での陰極電流密度の最小値に対する最大値の比を２〜５に制御することにより、積層構造の各層内での電流密度分布を均一化させて、金属層を構成する金属導電体の残留応力の更なる均一化を図る。これによって、積層構造全体での残留応力の均一化し、ばらつきを抑制することができる。すなわち、前記陰極電流密度の最小値に対する最大値の比が５を超えると、電流密度差による残留応力の差が大きく、ばらつきが大きくなってしまう。さらに、残留応力を均一化させるためには、陰極電流密度の陰極電流密度の最小値に対する最大値の比を２〜３とすることが好ましい。 Further, by controlling the ratio of the maximum value to the minimum value of the cathode current density in each plating tank to 2 to 5, the current density distribution in each layer of the laminated structure is made uniform, and the metal layer is configured. Further uniform the residual stress of the metal conductor. Thereby, the residual stress in the entire laminated structure can be made uniform and variation can be suppressed. That is, when the ratio of the maximum value to the minimum value of the cathode current density exceeds 5, the difference in residual stress due to the current density difference is large and the variation becomes large. Furthermore, in order to make the residual stress uniform, the ratio of the maximum value of the cathode current density to the minimum value of the cathode current density is preferably 2 to 3.
上記陰極電流密度の制御方法としては、一般に、電気めっきの初期段階、すなわち、金属被膜の表面抵抗が高い領域では、上記連続めっき装置の各めっき槽内では、給電を行なうローラーに近いめっき液入口界面に電流密度が極端に集中し易く、逆にめっき槽の底部では電流密度が大幅に低下するので、めっき槽入口での電流密度の集中を抑制するために適切な電流遮蔽板をポリイミドフィルム上の金属被膜と陽極の間に設置する方法等が望ましく、その手法は特に限定されない。例えば、電流遮蔽板として、絶縁板に開口部を設け、その開口面積を通常電流密度が集中するめっき液界面近傍では小さく、逆に電流密度が疎になるめっき槽の底部では大きくなるように調整する方法をとることができる。 As a method for controlling the cathode current density, in general, in an initial stage of electroplating, that is, in a region where the surface resistance of the metal film is high, in each plating tank of the continuous plating apparatus, a plating solution inlet close to a roller for supplying power The current density tends to be extremely concentrated at the interface, and conversely, the current density at the bottom of the plating tank drops significantly. Therefore, an appropriate current shielding plate is placed on the polyimide film to suppress the concentration of current density at the plating tank inlet. The method of installing between this metal film and an anode etc. is desirable, and the method is not specifically limited. For example, an opening is provided in an insulating plate as a current shielding plate, and the opening area is adjusted so that it is small near the plating solution interface where current density is normally concentrated and conversely large at the bottom of the plating tank where current density is sparse. You can take a method.
また、フィルムの搬送速度は、８０〜３００ｍ／ｈに調整することにより、半導体チップをボンディングによってＣＯＦに実装して半導体チップを樹脂封止した際に、リード表面のスズめっき皮膜が剥離する問題を回避することができる。すなわち、上記連続めっき装置は、複数のめっき槽と給電部、及び搬送機構からなるので、この装置を用いて金属導電体を積層構造に形成した場合、金属被膜及びその上に形成されためっき膜に給電するため、ポリイミド基板がめっき液外に存在する時間、すなわち積層構造の各層間にめっきの中断時間が生じる。このめっき中断時間が長くなると、得られた基板をエッチングによってリード形成し、その表面にスズめっき被膜を無電解めっきにより形成した後、半導体チップをボンディングによってＣＯＦに実装して半導体チップを樹脂封止した際に、リード表面のスズめっき皮膜が剥離する危険性が生じるという問題があった。 In addition, by adjusting the film conveyance speed to 80 to 300 m / h, when the semiconductor chip is mounted on the COF by bonding and the semiconductor chip is resin-sealed, the lead plating film peels off. It can be avoided. That is, since the continuous plating apparatus includes a plurality of plating tanks, a power feeding unit, and a transport mechanism, when a metal conductor is formed in a laminated structure using this apparatus, a metal film and a plating film formed thereon Since the power is supplied to the substrate, the time during which the polyimide substrate exists outside the plating solution, that is, the interruption time of plating occurs between the respective layers of the laminated structure. When this plating interruption time becomes long, leads are formed on the obtained substrate by etching, a tin plating film is formed on the surface by electroless plating, and then the semiconductor chip is mounted on COF by bonding and the semiconductor chip is resin-sealed In this case, there is a problem in that the tin plating film on the lead surface may be peeled off.
より詳しくは、半導体チップを樹脂封止する際に、１５０℃で３時間程度の熱負荷が加わった際、リード表層部でスズと銅の合金化が生じる際に拡散速度の差によって生じるボイド、所謂カーケンダルボイドが発生することが知られている。上記連続めっき装置で得られる銅めっき膜の積層構造においては、下層からの合金化に必要な銅イオンの供給が、積層構造界面の状態によっては遅延する。銅イオンの供給が遅延した状態では、リード表層部は、下層からの銅イオンの供給がない状態でスズ側に銅が拡散してボイドが急激に増加、拡大する危険性がある。これは、積層構造界面が酸化するほど、すなわちめっき液外にてめっきの中断時間が長くなるほどその危険性が高まる。このため、フィルムの搬送速度を一定以上とし、めっきの中断時間を一定時間以内に留めることによって、積層構造界面の酸化を抑制して、リード表面のスズめっき皮膜が剥離することを抑制する。 More specifically, when a semiconductor chip is resin-sealed, when a thermal load of about 3 hours is applied at 150 ° C., voids generated due to a difference in diffusion rate when tin and copper are alloyed in the lead surface layer portion, It is known that so-called Kirkendall voids are generated. In the laminated structure of the copper plating film obtained by the continuous plating apparatus, the supply of copper ions necessary for alloying from the lower layer is delayed depending on the state of the interface of the laminated structure. In the state where the supply of copper ions is delayed, the lead surface layer portion has a risk that the voids rapidly increase and expand due to the diffusion of copper to the tin side in the absence of the supply of copper ions from the lower layer. This risk increases as the laminated structure interface is oxidized, that is, as the plating interruption time is increased outside the plating solution. For this reason, the film conveyance speed is set to a certain value or more, and the plating interruption time is kept within a certain time, thereby suppressing the oxidation of the interface of the laminated structure and the peeling of the tin plating film on the lead surface.
すなわち、フィルムの搬送速度が８０ｍ／ｈ未満では、給電部を小型化してもめっき中断時間がおよそ３０秒以上となり、前記剥離の危険性が高くなる。一方、フィルムの搬送速度が３００ｍ／ｈを超えると、基板にキズ等が発生する危険が生じてしまう。さらに、フィルムの搬送速度が１００ｍ／ｈ以上とすることが、リード表面のスズめっき皮膜の剥離をなくすためには好ましい。 That is, when the film conveyance speed is less than 80 m / h, the plating interruption time becomes about 30 seconds or more even if the power feeding unit is downsized, and the risk of the peeling increases. On the other hand, when the film conveyance speed exceeds 300 m / h, there is a risk that the substrate is scratched. Furthermore, it is preferable that the film conveyance speed be 100 m / h or more in order to eliminate the peeling of the tin plating film on the lead surface.
上記連続めっき装置に用いる陽極としては、特に限定されるものではなく、可溶性又は不溶性陽極が用いられるが、この中で、不溶性陽極を用いることによって、より好ましい効果を示す電気めっきの条件で行うことができる。この際、全めっき槽の平均陰極電流密度は、１．５〜３．０Ａ／ｄｍ２に、各めっき槽内での陰極電流密度の最小値に対する最大値の比を１〜３に制御するとともに、フィルムの搬送速度は、１００〜３００ｍ／ｈに調整することが好ましい。なお、不溶性陽極は、一般に、銅めっきにおいて、可溶性陽極で問題となる含リン銅ボール表面に生成するスラッジ等がめっき液中に混入し、めっき外観品質を低下させる問題を防止するために用いられるが、金属被覆ポリイミド基板の製造方法において、残留応力のばらつきの抑制、めっき被膜耐折れ性等の観点から、不溶性陽極を用いて、めっき電流密度条件、基板搬送速度の最適化が可能となった。これは、不溶性陽極が有する表面電位の均一性、電極間距離の均一性が効果を発揮し、可溶性陽極に比較し電流密度の均一化が容易であることによる。 The anode used in the above continuous plating apparatus is not particularly limited, and a soluble or insoluble anode is used. Among them, an insoluble anode is used under the conditions of electroplating that shows a more preferable effect. Can do. At this time, the average cathode current density of all the plating tanks is 1.5 to 3.0 A / dm 2 and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank is controlled to 1 to 3. The film conveying speed is preferably adjusted to 100 to 300 m / h. Insoluble anodes are generally used in copper plating to prevent problems such as sludge generated on the surface of phosphorous-containing copper balls, which is a problem with soluble anodes, being mixed in the plating solution and deteriorating the appearance quality of plating. However, in the method of manufacturing a metal-coated polyimide substrate, it became possible to optimize the plating current density condition and the substrate conveyance speed by using an insoluble anode from the viewpoints of suppressing variation in residual stress and resistance to plating film folding. . This is because the uniformity of the surface potential of the insoluble anode and the uniformity of the distance between the electrodes are effective, and the current density is more uniform than the soluble anode.
上記可溶性陽極としては、特に限定されるものではなく、形成する金属導電体を構成する元素を含む市販の陽極が用いられるが、銅導電体を得る場合には、チタンボックスに含リン銅ボールを充填したものが用いられる。
不溶性陽極としては、特に限定されるものではなく、チタンを基体とした表面に白金族またはその酸化物の薄膜を形成したもの等が用いられるが、例えば、チタンメッシュ表面に酸化イリジウムをコーティングした構造のものが好ましい。
The soluble anode is not particularly limited, and a commercially available anode containing an element constituting the metal conductor to be formed is used. When obtaining a copper conductor, a phosphorus-containing copper ball is placed in a titanium box. Filled ones are used.
The insoluble anode is not particularly limited, and a titanium-based surface having a platinum group or oxide thin film formed thereon is used. For example, a structure in which a titanium mesh surface is coated with iridium oxide. Are preferred.
以下に、本発明の実施例及び比較例によって本発明をさらに詳細に説明するが、本発明は、これらの実施例によってなんら限定されるものではない。なお、実施例及び比較例で用いた金属被膜の表面抵抗、及び金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法は、以下の通りである。
（１）金属被膜の表面抵抗の測定：ＪＩＳ Ｋ７１９４に基づき四探針法で行った。
Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. In addition, the evaluation method when using as surface resistance of the metal film used in the Example and the comparative example and COF of the metal-coated polyimide substrate is as follows.
(1) Measurement of surface resistance of metal coating: Measured by a four-probe method based on JIS K7194.
（２）金属被覆ポリイミド基板のＣＯＦとして用いたときの評価：得られた金属被覆ポリイミド基板を用いて、サブトラクティブ法により、インナーリード部が２０μｍピッチ、アウターリード部が３５μmピッチのリードパターンを形成し、リード表面に無電解めっき法によって、厚さ０．６μmのスズ被膜を形成した。次に、スズめっき被膜におけるウイスカー発生を抑制することを目的として、１２０℃で６０分の熱処理を行い、さらに所望部分に厚さ１０μmのソルダーレジスト層を形成し、これを熱硬化させることを目的として１２０℃で２時間熱処理を行った。熱処理の後、インナーリード部とＩＣチップのパッド部を接合させるために、接合部を４２０℃で１秒間熱圧着し、さらにＩＣチップおよびその周辺部に熱硬化型樹脂を塗布し、１５０℃で３時間熱処理を行うことによってＩＣチップを樹脂封止した。さらにその後、アウターリード部と液晶パネルＩＴＯ電極とをＡＣＦ接合するため、接合部を２００℃で５秒間熱圧着した。
以上の処理を行った後、インナーリード部およびアウターリード部の接合部を観察し、位置ずれによる剥離等の不良発生率を求めた。
また、スズめっきの剥離性を示す指標は、加速試験を行なって評価した結果を用いた。すなわち、ロームアンドハース社製無電解めっき液Ｔｉｎｐｏｓｉｔ ＬＴ−３４を使用し、リード表面に厚さ０．６μmのスズめっき被膜を形成した後、１６０℃にて２４時間処理し、該リード部表面にセロハンテープを接着、十分粘着させた後、テープを剥離し、２００倍の金属顕微鏡にてスズめっき被膜の剥離の有無を確認した。
(2) Evaluation when used as COF of metal-coated polyimide substrate: Using the obtained metal-coated polyimide substrate, a lead pattern with inner lead portions of 20 μm pitch and outer lead portions of 35 μm pitch is formed by subtractive method. Then, a 0.6 μm thick tin coating was formed on the lead surface by electroless plating. Next, in order to suppress whisker generation in the tin plating film, heat treatment is performed at 120 ° C. for 60 minutes, and a solder resist layer having a thickness of 10 μm is formed on a desired portion, and this is thermoset. As a result, heat treatment was performed at 120 ° C. for 2 hours. After the heat treatment, in order to bond the inner lead portion and the pad portion of the IC chip, the bonding portion is thermocompression bonded at 420 ° C. for 1 second, and a thermosetting resin is applied to the IC chip and its peripheral portion at 150 ° C. The IC chip was resin-sealed by performing a heat treatment for 3 hours. Thereafter, in order to perform ACF bonding between the outer lead portion and the liquid crystal panel ITO electrode, the bonded portion was subjected to thermocompression bonding at 200 ° C. for 5 seconds.
After performing the above process, the joint part of an inner lead part and an outer lead part was observed, and defect incidence rates, such as peeling by position shift, were calculated | required.
Moreover, the index which showed the peelability of tin plating used the result evaluated by performing an accelerated test. That is, a tin plating film having a thickness of 0.6 μm was formed on the lead surface using an electroless plating solution Tinposit LT-34 manufactured by Rohm and Haas, and then treated at 160 ° C. for 24 hours. After the cellophane tape was adhered and sufficiently adhered, the tape was peeled off, and the presence or absence of peeling of the tin plating film was confirmed with a 200-fold metal microscope.
また、実施例及び比較例で用いた連続めっき装置は下記の通りである。
図１は、上記連続めっき装置の概略構造の一例を表す。図１において、連続めっき装置は、フィルム２の搬送と金属被膜とめっき膜への電力の供給を行うためのステンレス製の給電ローラー３、及びめっき槽１内部でフィルム２を反転させる反転ローラー４を有し、陽極５を備えためっき槽１の１７槽を搬送方向に並べて設置した例である。
なお、実施例及び比較例では、各めっき槽は、槽内のめっき長、すなわち、めっき液に浸漬されている距離が３０００ｍｍ、各めっき槽間でめっき面に電力を供給するためにめっき液外で基板が搬送される距離が７００mmである。また、使用しためっき槽数は、各条件によって適正化して必要槽数とした。さらに、アノードと金属被膜及びめっき膜間に種々の形状を有する電流遮蔽板を設置した。また、銅めっき浴は、硫酸を１８０ｇ／Ｌ、硫酸銅を８０ｇ／Ｌ、塩素イオンを５０ｍｇ／Ｌ、および銅めっき被膜の平滑性等を確保する目的で有機添加剤を所定量添加したものを用いた。
Moreover, the continuous plating apparatus used by the Example and the comparative example is as follows.
FIG. 1 shows an example of a schematic structure of the continuous plating apparatus. In FIG. 1, the continuous plating apparatus includes a feeding roller 3 made of stainless steel for carrying the film 2 and supplying power to the metal coating and the plating film, and a
In Examples and Comparative Examples, each plating tank has a plating length in the tank, that is, the distance immersed in the plating solution is 3000 mm, and the plating solution is external to supply power to the plating surface between the plating vessels. The distance to which the substrate is conveyed is 700 mm. In addition, the number of plating tanks used was optimized according to each condition to obtain the required number of tanks. Furthermore, current shielding plates having various shapes were installed between the anode, the metal film, and the plating film. Also, the copper plating bath should be 180 g / L of sulfuric acid, 80 g / L of copper sulfate, 50 mg / L of chlorine ions, and a predetermined amount of organic additives added for the purpose of ensuring the smoothness of the copper plating film. Using.
（実施例１）
まず、真空雰囲気中で行われるマグネトロンスパッタリング装置により、ポリイミドフィルムとして、Ｋａｐｔｏｎ 1５０ ＥＮ（東レ・デュポン製）を用いて、真空度０．０１〜０．１Ｐａに保持されたチャンバー内で、１５０℃で１分間の加熱処理を行った。引き続き、クロムを全量に対し２０質量％含有するニッケルクロム合金ターゲットと銅ターゲットを用い、ポリイミドフィルム表面に厚さ２０ｎｍのニッケルクロム合金層及び厚さ３００ｎｍの銅層を形成した。得られた金属被膜の表面抵抗は、０．１Ω／□であった。
次いで、得られたスパッタリング後のポリイミドフィルムを用いて、上記連続めっき装置（めっき槽数：１７槽）で、銅被膜上に銅めっき層を積層して銅導電体を形成した金属被覆ポリイミド基板を得た。ここで、上記連続めっき装置の陽極として、チタンボックスに含リン銅ボールを充填し、ボックスの周囲をポリプロピレン製のバックで覆った可溶性陽極を用いた。また、全めっき槽の平均電流密度（以下、全平均電流密度と呼称する場合がある。）１．０Ａ／ｄｍ２、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を５に制御し、同時にフィルムの搬送速度を８０ｍ／ｈに調整しながら、厚さ８μmまでめっき膜からなる銅導電体を形成した。
Example 1
First, using a Kapton 150 EN (manufactured by Toray DuPont) as a polyimide film with a magnetron sputtering apparatus performed in a vacuum atmosphere, at 150 ° C. in a chamber maintained at a vacuum degree of 0.01 to 0.1 Pa. Heat treatment for 1 minute was performed. Subsequently, a nickel chromium alloy target containing 20% by mass of chromium and a copper target were used, and a nickel chromium alloy layer having a thickness of 20 nm and a copper layer having a thickness of 300 nm were formed on the surface of the polyimide film. The surface resistance of the obtained metal coating was 0.1Ω / □.
Next, using the obtained polyimide film after sputtering, a metal-coated polyimide substrate in which a copper conductor was formed by laminating a copper plating layer on a copper film using the above continuous plating apparatus (number of plating tanks: 17 tanks). Obtained. Here, a soluble anode in which a titanium box was filled with phosphorus-containing copper balls and the periphery of the box was covered with a back made of polypropylene was used as the anode of the continuous plating apparatus. Further, the average current density of all plating tanks (hereinafter sometimes referred to as the total average current density) 1.0 A / dm 2 , and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank At the same time, the copper conductor made of a plating film was formed to a thickness of 8 μm while adjusting the film conveyance speed to 80 m / h.
その後、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。 Then, using the obtained metal-coated polyimide substrate, the above-mentioned [Evaluation method when used as COF of metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints, the rate of occurrence of lead disconnection, and the occurrence of tin plating peeling The rate was determined. The results are shown in Table 1.
（実施例２）
各めっき槽内での陰極電流密度の最小値に対する最大値の比を３に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Example 2)
Except that the ratio of the maximum value to the minimum value of the cathode current density in each plating tank was controlled to 3, it was carried out in the same manner as in Example 1, and using the obtained metal-coated polyimide substrate, the above-mentioned [metal-coated polyimide] Evaluation method when used as COF of substrate] The misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1.
（実施例３）
上記連続めっき装置のめっき槽数が１２槽で、全平均電流密度を１．５Ａ／ｄｍ２に制御したこと、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を３に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Example 3)
The number of plating tanks in the above continuous plating apparatus is 12, and the total average current density is controlled to 1.5 A / dm 2 and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank is set to 3. Except for control, the same procedure as in Example 1 was performed, and the obtained metal-coated polyimide substrate was used, and the above-mentioned [Evaluation method when used as a COF of a metal-coated polyimide substrate] resulted in misalignment of the COF joint portion. The occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate were determined. The results are shown in Table 1.
（実施例４）
上記連続めっき装置のめっき槽数が６槽で、全平均電流密度を３．０Ａ／ｄｍ２に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
Example 4
The number of plating tanks of the above continuous plating apparatus is 6, and the same as in Example 1 except that the total average current density is controlled to 3.0 A / dm 2 , and using the obtained metal-coated polyimide substrate, According to the above [Evaluation method when used as COF of metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints, the occurrence rate of lead disconnection, and the occurrence rate of tin plating peeling were determined. The results are shown in Table 1.
（実施例５）
上記連続めっき装置のめっき槽数が１５槽で、不溶性陽極を用いたこと、全平均電流密度が１．５Ａ／ｄｍ２に制御したこと、各めっき槽内での陰極電流密度の最小値に対する最大値の比を３に制御したこと、及びフィルムの搬送速度を１００ｍ／ｈに調整したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。なお、不溶性陽極としては、チタンメッシュ表面に酸化イリジウムをコーティングしたもので、めっき槽内で金属被膜及びめっき膜と対向するように設置された。
(Example 5)
The number of plating tanks of the above continuous plating apparatus is 15 tanks, an insoluble anode is used, the total average current density is controlled to 1.5 A / dm 2 , and the maximum of the minimum value of the cathode current density in each plating tank. Except that the ratio of the values was controlled to 3 and the film conveyance speed was adjusted to 100 m / h, the same procedure as in Example 1 was performed, and the obtained metal-coated polyimide substrate was used. Evaluation method when used as COF of substrate] The misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1. The insoluble anode was a titanium mesh surface coated with iridium oxide, and was placed so as to face the metal film and the plating film in the plating tank.
（実施例６）
上記連続めっき装置のめっき槽数が２３槽で、不溶性陽極を用いたこと、全平均電流密度を１．５Ａ／ｄｍ２に制御したこと、各めっき槽内での陰極電流密度の最小値に対する最大値の比を２に制御したこと、及びフィルムの搬送速度を１５０ｍ／ｈに調整したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。なお、不溶性陽極としては、チタンメッシュ表面に酸化イリジウムをコーティングしたものを、めっき槽内で金属被膜及びめっき膜と対向するように設置した。
(Example 6)
The number of plating tanks in the continuous plating apparatus is 23, the insoluble anode is used, the total average current density is controlled to 1.5 A / dm 2 , the maximum of the minimum value of the cathode current density in each plating tank. Except that the ratio of the values was controlled to 2 and the film conveyance speed was adjusted to 150 m / h, the same procedure as in Example 1 was performed, and the obtained metal-coated polyimide substrate was used. Evaluation method when used as COF of substrate] The misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1. As the insoluble anode, a titanium mesh surface coated with iridium oxide was placed in the plating tank so as to face the metal film and the plating film.
（実施例７）
上記連続めっき装置のめっき槽数が８槽で、不溶性陽極を用いたこと、全平均電流密度を３．０Ａ／ｄｍ２に制御したこと、各めっき槽内での陰極電流密度の最小値に対する最大値の比を３に制御したこと、及びフィルムの搬送速度を１００ｍ／ｈに調整したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。なお、不溶性陽極としては、チタンメッシュ表面に酸化イリジウムをコーティングしたものを、めっき槽内で金属被膜及びめっき膜と対向するように設置した。
(Example 7)
The number of plating tanks in the above continuous plating apparatus is 8, and an insoluble anode is used; the total average current density is controlled to 3.0 A / dm 2 ; the maximum for the minimum value of the cathode current density in each plating tank Except that the ratio of the values was controlled to 3 and the film conveyance speed was adjusted to 100 m / h, the same procedure as in Example 1 was performed, and the obtained metal-coated polyimide substrate was used. Evaluation method when used as COF of substrate] The misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1. As the insoluble anode, a titanium mesh surface coated with iridium oxide was placed in the plating tank so as to face the metal film and the plating film.
（実施例８）
スパッタリングで厚さ１０ｎｍの銅層を形成し、金属被膜の表面抵抗が１．０Ω／□であったこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Example 8)
A copper layer having a thickness of 10 nm was formed by sputtering, and the same procedure as in Example 1 was performed except that the surface resistance of the metal film was 1.0 Ω / □. According to [Evaluation Method when Used as COF of Metal-Coated Polyimide Substrate], the misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1.
（実施例９）
スパッタリングで厚さ１０ｎｍの銅層を形成し、金属被膜の表面抵抗が１．０Ω／□であったこと、及び上記連続めっき装置のめっき槽数が６槽で、全平均電流密度を３．０Ａ／ｄｍ２に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
Example 9
A copper layer having a thickness of 10 nm was formed by sputtering, the surface resistance of the metal film was 1.0 Ω / □, and the number of plating tanks of the continuous plating apparatus was 6, and the total average current density was 3.0 A. Except that it was controlled to / dm 2 , it was carried out in the same manner as in Example 1, and the obtained metal-coated polyimide substrate was used, and the above [Evaluation method when used as COF of metal-coated polyimide substrate] The occurrence rate of misalignment, lead disconnection rate, and tin plating peeling rate were determined. The results are shown in Table 1.
（実施例１０）
スパッタリングで厚さ１０ｎｍの銅層を形成し、金属被膜の表面抵抗が１．０Ω／□であったこと、上記連続めっき装置のめっき槽数が１５槽で、不溶性陽極を用いたこと、全平均電流密度を１．５Ａ／ｄｍ２に制御したこと、各めっき槽内での陰極電流密度の最小値に対する最大値の比を３に制御したこと、及びフィルムの搬送速度を１００ｍ／ｈに調整したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。なお、不溶性陽極としては、チタンメッシュ表面に酸化イリジウムをコーティングしたものを、めっき槽内で金属被膜及びめっき膜と対向するように設置した。
(Example 10)
A copper layer having a thickness of 10 nm was formed by sputtering, the surface resistance of the metal film was 1.0 Ω / □, the number of plating tanks in the continuous plating apparatus was 15, and an insoluble anode was used. The current density was controlled to 1.5 A / dm 2 , the ratio of the maximum value to the minimum value of the cathode current density in each plating tank was controlled to 3, and the film conveyance speed was adjusted to 100 m / h. Except for the above, it was carried out in the same manner as in Example 1, and using the obtained metal-coated polyimide substrate, the above-mentioned [Evaluation method when used as a COF of a metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints Then, the lead disconnection occurrence rate and the tin plating peeling occurrence rate were determined. The results are shown in Table 1. As the insoluble anode, a titanium mesh surface coated with iridium oxide was placed in the plating tank so as to face the metal film and the plating film.
（実施例１１）
スパッタリングで厚さ１０ｎｍの銅層を形成し、金属被膜の表面抵抗が１．０Ω／□であったこと、上記連続めっき装置のめっき槽数が８槽で、不溶性陽極を用いたこと、全平均電流密度を３．０Ａ／ｄｍ２に制御したこと、各めっき槽内での陰極電流密度の最小値に対する最大値の比を３に制御したこと、及びフィルムの搬送速度を１００ｍ／ｈに調整したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。なお、不溶性陽極としては、チタンメッシュ表面に酸化イリジウムをコーティングしたものを、めっき槽内で金属被膜及びめっき膜と対向するように設置した。
(Example 11)
A copper layer having a thickness of 10 nm was formed by sputtering, the surface resistance of the metal film was 1.0 Ω / □, the number of plating tanks in the continuous plating apparatus was 8, and an insoluble anode was used. The current density was controlled to 3.0 A / dm 2 , the ratio of the maximum value to the minimum value of the cathode current density in each plating tank was controlled to 3, and the film conveyance speed was adjusted to 100 m / h. Except for the above, it was carried out in the same manner as in Example 1, and using the obtained metal-coated polyimide substrate, the above-mentioned [Evaluation method when used as a COF of a metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints Then, the lead disconnection occurrence rate and the tin plating peeling occurrence rate were determined. The results are shown in Table 1. As the insoluble anode, a titanium mesh surface coated with iridium oxide was placed in the plating tank so as to face the metal film and the plating film.
（比較例１）
スパッタリングで厚さ１０００ｎｍの銅層を形成し、金属被膜の表面抵抗が０．０９Ω／□であったこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Comparative Example 1)
A copper layer having a thickness of 1000 nm was formed by sputtering, and the same procedure as in Example 1 was performed except that the surface resistance of the metal film was 0.09 Ω / □. According to [Evaluation Method when Used as COF of Metal-Coated Polyimide Substrate], the misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1.
（比較例２）
スパッタリングで厚さ５ｎｍの銅層を形成し、金属被膜の表面抵抗を１．１Ω／□であったこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Comparative Example 2)
A copper layer having a thickness of 5 nm was formed by sputtering, and the surface resistance of the metal film was 1.1 Ω / □, except that the same procedure as in Example 1 was performed. According to [Evaluation Method when Used as COF of Metal-Coated Polyimide Substrate], the misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1.
（比較例３）
上記連続めっき装置のめっき槽数が２０槽で、全平均電流密度を０．９Ａ／ｄｍ２に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Comparative Example 3)
The number of plating tanks of the above continuous plating apparatus is 20, and the same is performed as in Example 1 except that the total average current density is controlled to 0.9 A / dm 2. Using the obtained metal-coated polyimide substrate, According to the above [Evaluation method when used as COF of metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints, the occurrence rate of lead disconnection, and the occurrence rate of tin plating peeling were determined. The results are shown in Table 1.
（比較例４）
上記連続めっき装置のめっき槽数が５槽で、全平均電流密度を３．５Ａ／ｄｍ２に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Comparative Example 4)
The number of plating tanks of the above continuous plating apparatus is 5 tanks, except that the total average current density is controlled to 3.5 A / dm 2 , the same as in Example 1 and using the obtained metal-coated polyimide substrate, According to the above [Evaluation method when used as COF of metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints, the occurrence rate of lead disconnection, and the occurrence rate of tin plating peeling were determined. The results are shown in Table 1.
（比較例５）
各めっき槽内での陰極電流密度の最小値に対する最大値の比を６に制御したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Comparative Example 5)
Except that the ratio of the maximum value to the minimum value of the cathode current density in each plating tank was controlled to 6, it was carried out in the same manner as in Example 1, and using the obtained metal-coated polyimide substrate, the above-mentioned [metal-coated polyimide] Evaluation method when used as COF of substrate] The misalignment defect occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate of the COF joint were determined. The results are shown in Table 1.
（比較例６）
上記連続めっき装置のめっき槽数が１６槽であったこと、フィルムの搬送速度を７０ｍ／ｈに調整したこと以外は、実施例１と同様に行い、得られた金属被覆ポリイミド基板を用いて、上記［金属被覆ポリイミド基板のＣＯＦとして用いたときの評価方法］により、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率及びスズめっき剥離発生率を求めた。結果を表１に示す。
(Comparative Example 6)
Except that the number of plating tanks of the continuous plating apparatus was 16, and the film conveyance speed was adjusted to 70 m / h, the same was carried out as in Example 1, and using the obtained metal-coated polyimide substrate, According to the above [Evaluation method when used as COF of metal-coated polyimide substrate], the occurrence rate of misalignment of COF joints, the occurrence rate of lead disconnection, and the occurrence rate of tin plating peeling were determined. The results are shown in Table 1.
表１より、実施例１〜１１では、スパッタリング工程において、形成する金属被膜の表面抵抗が、０．１〜１．０Ω／□に制御され、電気めっき工程において、陰極電流密度は、全めっき槽の平均陰極電流密度を１〜３Ａ／ｄｍ２に、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を１〜５に制御するとともに、フィルムの搬送速度は、８０〜３００ｍ／ｈに調整されて、本発明の製造方法に従って金属被覆ポリイミド基板が製造されたので、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率、及びスズめっき剥離発生率はいずれも０．０１％未満であり、良好であると判断できた。 From Table 1, in Examples 1-11, the surface resistance of the metal film to be formed is controlled to 0.1 to 1.0 Ω / □ in the sputtering process, and the cathode current density is the total plating tank in the electroplating process. The average cathode current density is controlled to 1 to 3 A / dm 2 and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank is controlled to 1 to 5, and the film transport speed is 80 to 300 m. Since the metal-coated polyimide substrate was manufactured according to the manufacturing method of the present invention, the COF joint misalignment occurrence rate, lead disconnection occurrence rate, and tin plating peeling occurrence rate were all 0.01. It was less than% and was judged to be good.
これに対して、比較例１〜６では、金属被膜の表面抵抗、全めっき槽の平均陰極電流密度、各めっき槽内での陰極電流密度の最小値に対する最大値の比又はフィルムの搬送速度のいずれかがこれらの条件を満足しないので、ＣＯＦ接合部の位置ずれ不良発生率、リード断線発生率、又はスズめっき剥離発生率のいずれかが０．０１％以上であり、これらの条件で得られた金属被覆ポリイミド基板は、生産性、収率、及び信頼性の点で十分に良好であるとは言えない。 On the other hand, in Comparative Examples 1 to 6, the surface resistance of the metal coating, the average cathode current density of all plating tanks, the ratio of the maximum value to the minimum value of the cathode current density in each plating tank, or the film transport speed Since any of these conditions does not satisfy these conditions, any of the misalignment occurrence rate, lead disconnection occurrence rate, or tin plating peeling occurrence rate of the COF joint is 0.01% or more, and obtained under these conditions. The metal-coated polyimide substrate cannot be said to be sufficiently good in terms of productivity, yield, and reliability.
以上より明らかなように、本発明の製造方法によって得られる金属被覆ポリイミド基板は、インナーリード２０μmピッチ、アウターリード３５μmピッチに代表される狭ピッチのＣＯＦに好適に用いられる。これにより、ＩＣおよび液晶パネルの組み立て工程においてインナーリード部とＩＣチップ、およびアウターリード部と液晶パネルの接合時の剥離等の問題、リード断線等の問題、及びスズめっき剥離等の発生の危険性を十分に抑制できる。さらに、本発明の製造方法は、めっき生産性の向上も期待できるので、生産性、及び経済性においても有効である。本発明によって得られる金属被覆ポリイミド基板は、ＣＯＦ以外の他のＰＷＢ、ＦＰＣ、ＴＡＢ等のフレキシブル基板へも好適に用いることができる。 As apparent from the above, the metal-coated polyimide substrate obtained by the production method of the present invention is suitably used for a narrow pitch COF represented by an inner lead 20 μm pitch and an outer lead 35 μm pitch. Due to this, in the assembly process of the IC and the liquid crystal panel, problems such as peeling at the time of joining the inner lead part and the IC chip and the outer lead part and the liquid crystal panel, problems such as lead disconnection, and risk of occurrence of tin plating peeling, etc. Can be sufficiently suppressed. Furthermore, since the production method of the present invention can be expected to improve plating productivity, it is also effective in productivity and economy. The metal-coated polyimide substrate obtained by the present invention can be suitably used for flexible substrates other than COF such as PWB, FPC, and TAB.
１ めっき槽
２ フィルム
３ 給電ローラー
４ 反転ローラー
５ 陽極
1 Plating tank 2 Film 3
Claims (5)
下記の（１）及び（２）の要件を満足することを特徴とする金属被覆ポリイミド基板の製造方法。
（１）前記スパッタリング工程において、形成する金属被膜の表面抵抗を、０．１〜１．０Ω／□に制御し、かつ、銅層の厚さを５０〜５００ｎｍに制御する。
（２）前記電気めっき工程において、陰極電流密度は、全めっき槽の平均陰極電流密度を１〜３Ａ／ｄｍ２に、及び各めっき槽内での陰極電流密度の最小値に対する最大値の比を２〜５に制御するとともに、フィルムの搬送速度は、８０〜１５０ｍ／ｈに調整する。 Sputtering process for forming a metal film having a copper layer on the surface of the polyimide film, and a roller for feeding the film and supplying power to the metal film on the metal film of the obtained polyimide film, and an anode facing the metal film A method for producing a metal-coated polyimide substrate including an electroplating step of forming a metal conductor using a continuous plating apparatus comprising at least two plating tanks provided with:
A method for producing a metal-coated polyimide substrate, which satisfies the following requirements (1) and (2):
(1) In the sputtering step, the surface resistance of the metal film to be formed is controlled to 0.1 to 1.0 Ω / □ , and the thickness of the copper layer is controlled to 50 to 500 nm .
(2) In the electroplating step, the cathode current density is determined by setting the average cathode current density of all plating tanks to 1 to 3 A / dm 2 and the ratio of the maximum value to the minimum value of the cathode current density in each plating tank. While controlling to 2-5, the conveyance speed of a film is adjusted to 80-150 m / h.
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| CN2008100969448A CN101350315B (en) | 2007-07-20 | 2008-05-12 | Manufacturing method of metal-coated polyimide substrate |
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| CN102477549B (en) * | 2010-11-25 | 2014-04-16 | 中国电子科技集团公司第十八研究所 | Method for depositing semiconductor film on flexible substrate |
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| JP5858286B2 (en) * | 2012-01-11 | 2016-02-10 | 住友金属鉱山株式会社 | Method for electrolytic plating long conductive substrate and method for producing copper clad laminate |
| CN104247576B (en) * | 2012-04-24 | 2017-05-31 | 住友金属矿山株式会社 | 2 layers of flexible wiring substrate and flexible wiring and its manufacture method |
| CN104216149B (en) * | 2014-09-30 | 2017-03-22 | 南京中电熊猫液晶显示科技有限公司 | Liquid crystal display panel with repair wire structure |
| WO2016208609A1 (en) * | 2015-06-26 | 2016-12-29 | 住友金属鉱山株式会社 | Conductive substrate |
| JP6880723B2 (en) | 2016-12-27 | 2021-06-02 | 住友金属鉱山株式会社 | Double-sided metal laminate, double-sided metal laminate manufacturing method, and pattern image transfer method |
| JP7273361B2 (en) * | 2019-02-28 | 2023-05-15 | 住友金属鉱山株式会社 | Flexible substrate manufacturing method |
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