JP2004360029A

JP2004360029A - Copper alloy foil for printed wiring and method for producing the same

Info

Publication number: JP2004360029A
Application number: JP2003161302A
Authority: JP
Inventors: Kenji Yokomizo; 健治横溝; Yasuyuki Ito; 保之伊藤; Hajime Sasaki; 元佐々木; Koji Aoyanagi; 幸司青柳
Original assignee: Hitachi Cable Ltd
Current assignee: Hitachi Cable Ltd
Priority date: 2003-06-05
Filing date: 2003-06-05
Publication date: 2004-12-24
Anticipated expiration: 2023-06-05
Also published as: JP4059150B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper alloy foil for printed wiring excellent in heat resistance, flex resistance, folding resistance, and electric conductivity, and to provide a method for producing the same. <P>SOLUTION: The copper alloy foil for printed wiring, which is the most suitable for use in a flexible printed wiring circuit (FPC) board, can be obtained by adding 0.01 to 0.20 wt.% (in terms of a weight ratio to the total elements) Zr to oxygen-free copper so as to attain a tensile strength of 400 N/mm<SP>2</SP>or higher and an electric conductivity of 90% IACS or higher and forming the copper into a copper foil excellent in heat resistance, flex resistance, folding resistance, and electric conductivity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、プリント配線用銅合金箔及びその製造方法に関し、特に、ＦＰＣ（ＦｌｅｘｉｂｌｅＰｒｉｎｔＣｉｒｃｕｉｔｂｏａｒｄ：フレキシブルプリント回路板）等の銅箔に用いるのに適したプリント配線用銅合金箔及びその製造方法に関する。
【０００２】
【従来の技術】
半導体の実装や電子機器の実装に用いられるＦＰＣ、ＣＯＦ（ＣｈｉｐＯｎｆｉｌｍ：チップオンフィルム）、ＴＡＢ（ＴａｐｅＡｕｔｏｍａｔｅｄＢｏｎｄｉｎｇ：テープオートメーテッドボンディング）等においては、フィルム状の絶縁体の片面又は両面に配線用の銅箔が形成されている。この銅箔はＦＰＣの場合、可撓性に優れる圧延箔が用いられる。圧延箔は、圧延ロールによる塑性加工により薄く延ばすことによって製造され、その素材には、従来よりタフピッチ銅（ＴＰＣ）や無酸素銅（ＯＦＣ）が用いられている。通常、ＦＰＣにおいてはＴＰＣが用いられ、ＯＦＣは用いられていない。
【０００３】
圧延加工による銅箔は、通常、最終焼鈍からの加工度が８０％以上になる。このため、加熱により軟化させ、圧延加工により緻密になっている加工組織が再結晶により粗大化し、強度が低下する。例えば、最終加工度が９０％の１０μｍタフピッチ銅を用いた場合は１５０℃で３０分程度の熱処理、無酸素銅においては１８０℃で３０分程度の熱処理を施すと、引張強さは２００Ｎ／ｍｍ^２以下にまで低下する。
【０００４】
タフピッチ銅（ＴＰＣ）を用いたＦＰＣの場合、ポリイミド樹脂フィルムと貼り合わせ、キュア（１５０〜１６０℃の熱処理）する際、銅箔を軟化させることで再結晶が行われ、集合組織になることで屈曲特性が向上する。しかし、素材に無酸素銅（ＯＦＣ）を使用した場合、キュア温度では再結晶が不十分で屈曲特性を向上できない。そのため、従来、ＯＦＣを用いた場合、軟化温度を下げる様にしていた。
【０００５】
一方、プリント配線板は、配線ピッチが狭くなる傾向にあり、ファインパターン化のために薄肉化が進んでいる。また、ＦＰＣ、ＴＡＢ、ＣＯＦなどにおいては、ファインパターン化のため、ポリイミドフィルムなどの接着材を用いて貼り合わせていた従来の３層基材に代わり、近年では、寸法安定性、耐熱性（鉛フリーはんだの高温化）や折り曲げ性に優れた２層基材の使用が多くなってきている。２層基材は、基材の製造工程や圧着時に３００〜４００℃の熱処理が加わるため、従来の３層基材の１００〜２００℃に比べて処理温度が高くなっている。
【０００６】
例えば、素材に無酸素銅（ＯＦＣ）を用い、１時間の等時軟化特性における半軟化温度が１８０℃以上となる加工度をもって圧延し、接着剤の加熱キュア温度では軟化しない１９０℃程度の軟化温度、及び４２ｋｇ／ｍｍ^２程度の引張強度が得られる無酸素銅圧延銅箔が提案されている（例えば、特許文献１参照）。
【０００７】
また、強度の向上を素材の組成により達成しようという試みもなされており、例えば、ジルコニウム（Ｚｒ）を０．０１〜０．２５％を含有し、残部を銅（電気銅又は無酸素銅）及び不可避不純物とし、更に、表面粗さを所定値にすることで、所要の導電性と強度が得られるようにした銅合金箔も提案されている（例えば、特許文献２参照）。特に、添加物の素材と組成、及び表面粗さを特定することによって表面欠陥を少なくし、高周波におけるインピーダンスを低減することができる。
【０００８】
ところが、従来のＴＰＣやＯＦＣによる銅箔は、耐熱性が１５０〜１９０℃程度であるため、３００〜４００℃の熱処理を行うと軟化してしまう。この結果、強度が低下し、ラインなどでのハンドリング性が悪化し、また、薄肉化が困難であったり、圧着性に問題が出たり、耐折性が十分に得られない等の欠点がある。
【０００９】
近年、ＦＰＣ、ＴＡＢ、ＣＯＦ等は、携帯機器の小型化に伴って使用環境がより厳しいものになっている。例えば、ＦＰＣの場合、稼動部の配線に必要な耐屈曲特性が重要である。そこで、銅箔には従来より圧延銅箔が用いられ、キュアー時の熱処理で銅箔の再結晶集合組織を発達させることで、屈曲特性を向上させている。
【００１０】
【特許文献１】
特公平６−６６３６３号
【特許文献２】
特開２００２−３８２２６号
【００１１】
【発明が解決しようとする課題】
しかし、従来のプリント配線用銅箔によると、特許文献２の構成では、表面欠陥の低減に伴う高周波域のインピーダンス低減に有効であり、アンテナ等への用途には適するが、用途がＦＰＣの場合には、要求される屈曲性や耐折性について考慮されておらず、また、導電率もＦＰＣに用いるには低すぎる。このため、ＦＰＣには適用できない。
【００１２】
また、前述のように、キュアー時の熱処理で銅箔の再結晶集合組織を発達させることで、屈曲特性を向上させた場合、銅箔強度の低下が生じ、実装時の折り曲げなどを繰り返し行う際、耐折性が落ちるという問題が生じる。
【００１３】
半導体、電子回路、電子機器等においては、更なる小型化、高実装化が求められており、プリント配線用銅箔に対して屈曲特性と耐折性を両立させる銅箔が要求されているが、この要求を満たすプリント配線用銅箔は、従来、存在しなかった。
【００１４】
したがって、本発明の目的は、耐熱性、屈曲性、耐折性、及び導電性のそれぞれに優れるプリント配線用銅合金箔及びその製造方法を提供することにある。
【００１５】
【課題を解決するための手段】
本発明は、上記の目的を達成するため、第１の特徴として、添加元素の成分の割合でＺｒの重量割合が０．０１〜０．２０ｗ％の範囲であり、残部が銅および不可避不純物であるとともに、引張強さが４００Ｎ／ｍｍ^２以上、及び導電率が９０％ＩＡＣＳ以上であることを特徴とするプリント配線用銅合金箔を提供する。
【００１６】
この構成によれば、Ｚｒが０．０１〜０．２０ｗ％の範囲で銅および不可避不純物の中に含有することで、４００Ｎ／ｍｍ^２以上の引張強さと９０％ＩＡＣＳ以上の導電率を有する銅合金箔が得られ、これにより、耐温度性、高屈曲性、高耐折性、及び高導電性を備えたプリント配線用銅合金箔を得ることができる。
【００１７】
本発明は、上記の目的を達成するため、第２の特徴として、添加元素の成分の割合でＺｒの重量割合が０．０１〜０．２０ｗ％であり、残部が銅および不可避不純物である鋳塊を作成し、前記鋳塊に熱間圧延、冷間圧延、及び焼鈍を適宜施して所定の厚さの素材に加工し、前記素材に所定の温度及び所定の時間による熱処理を施し、２５０Ｎ／ｍｍ^２以上の引張強さ、及び９０％ＩＡＣＳ以上の導電率を有するように、前記素材に所定の温度及び所定の時間による熱処理を施すことを特徴とするプリント配線用銅合金箔の製造方法を提供する。
【００１８】
この方法によれば、銅および不可避不純物に０．０１〜０．２０ｗ％のＺｒを含む鋳塊を元に、圧延及び焼鈍を施して所定の厚さの素材とし、これに所定の温度と時間による熱処理を施すことで、２５０Ｎ／ｍｍ^２以上の引張強さと９０％ＩＡＣＳ以上の導電率を有するプリント配線用銅合金箔を製造でき、これにより、耐温度性、高屈曲性、高耐折性、及び高導電性を備えたプリント配線用銅合金箔を得ることができる。
【００１９】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
本発明の実施の形態に係るプリント配線用銅合金箔は、添加元素の成分の割合でＺｒ（ジルコニウム）の重量割合を０．０１〜０．２０ｗ％とし、残部を銅および不可避不純物とすることにより、引張強さを４００Ｎ／ｍｍ^２以上、導電率を９０％ＩＡＣＳ以上を得ようとするものである。Ｚｒの含有を０．０１〜０．２０ｗ％とすることにより、銅に固溶状態で含まれるＰやＳが析出され、耐熱特性が向上する。更に、かかるプリント配線用銅合金箔に対し、最終工程で熱処理を行い、２５０Ｎ／ｍｍ^２以上の引張強さを得ようとするものである。
【００２０】
ここで、Ｚｒの添加量を０．０１５ｗ％以下にすると、固溶量が足りなくなり、加熱処理時の結晶粒の粗大化を防止できない。また、Ｚｒが０．２０ｗｔ％を超えると、加工性の低下と共に導電率も低下し、プリント配線板の導体には不向きになる。
【００２１】
次に、本発明の実施例について説明する。本実施例においては、酸素含有量が１０ｐｐｍの無酸素銅をベース材とし、これにＺｒを添加して溶解鋳造し、試料Ｎｏ．１〜５を作製した。ここで、試料Ｎｏ．１〜５は、それぞれ０．０１ｗｔ％、０．０５ｗｔ％、０．１ｗｔ％、０．１５ｗｔ％、０．２０ｗｔ％のＺｒの添加とした。
【００２２】
ついで、上記鋳塊のそれぞれを熱間圧延し、厚さ１２ｍｍの素材に加工した後、冷間圧延と焼鈍を繰り返す方法で加工し、厚さ１２μｍまで冷間圧延して試料とした。以上の試料を４５０℃×４時間の還元雰囲気で熱処理を行った後、特性を確認したところ、〔表１〕に示す特性が得られた。
【００２３】
【表１】

【００２４】
〔表１〕に示すように、いずれの試料も、４５０℃で４時間の熱処理に対し、十分な強度を得られることが確認できた。この銅箔を用いて２層基材を製造した。〔表１〕の試料Ｎｏ．１〜５のいずれを用いた場合でも、銅箔にシワ等を発生しない２層基材を得ることができた。
【００２５】
図１は、屈曲特性を確認するための試験機の構成を示す。試験機１０は、逆Ｗの字形にした導体１の両端部を固定するための導体固定部２ａ，２ｂ，２ｃ，２ｄと、導体１の中央部に当接されると共に導体１に振動を付与する振動付加部３と、発生させた振動を振動付加部３に伝達させる振動発生源としての振動発生装置４と、振動発生装置４を支持する支持部５ａ，５ｂとを備えて構成されている。
【００２６】
〔表１〕の試料Ｎｏ．１〜５について、図１の試験機を用いて屈曲特性を確認した。試験条件は、試験片幅：１２．７ｍｍ、試験片長さ：２００ｍｍ、試験片採取方向：圧延方向、曲率半径ｒ：２．５ｍｍ、振動ストローク：１０ｍｍ、振動速度：１５００回／分とした。あわせてＩＰＣ規格で定義された図２に示すようなＭＩＴ試験機により耐折性を測定した。
【００２７】
図２は、耐折性の測定に用いたＭＩＴ試験機を示す。このＭＩＴ試験機２０は、導体１の一端を固定する固定部６と、導体１の他端を把持しながら設定した角度を折り曲げるチャック部７とを備えて構成されている。ここで、ＭＩＴ試験機２０の試験条件は、１３５°の角度の振りで、曲げＲは２ｍｍとした。即ち、チャック部７は１３５°の曲げ範囲に設定し、導体１の一端を固定部６で上方向に引っ張る状態に固定しながら、他端をチャック部７で把持して１３５°に折り曲げる動作を繰り返し測定した。その測定結果として、〔表２〕が得られた。
【００２８】
【表２】

【００２９】
〔表２〕は、耐折性の測定結果を示す。この測定は、圧延上がりの銅箔（圧延のみの銅箔）と、４５０℃×４時間の熱処理を加えることにより行った。〔表２〕を参照すると、熱処理を行ったものは、圧延上がりの銅箔と比較して、屈曲特性が約１０％、更に耐折性が約５０％向上することを確認できた。
【００３０】
〔表１〕及び〔表２〕から明らかな様に、本発明の実施例によれば、Ｚｒを無酸素銅に０．０１〜０．２０ｗ％を添加したことにより、耐熱性が向上し、これに伴って屈曲性、耐折性が向上し、かつＦＰＣで必要とする導電率をも確保することが可能になった。更に、所定の熱処理を施すことにより、屈曲性及び耐折性は更に向上させることができるようになる。
【００３１】
本発明者らは、上記実施例に対し、比較材Ｎｏ．６〜８を用意して比較検討を行った。ここでは、通常の無酸素銅を比較材Ｎｏ．６、Ｚｒを少なく添加（０．００５ｗｔ％）したものを比較材Ｎｏ．７、Ｚｒを多く添加（０．３％）したものを比較材Ｎｏ．８とした。この比較例における測定結果が〔表３〕である。
【００３２】
【表３】

【００３３】
〔表３〕を参照すると、Ｚｒ添加量の低い比較材Ｎｏ．６，７は、熱処理後の強度が落ちており、十分な強度を有していない。また、Ｚｒ添加量の多い比較材Ｎｏ．８は、熱処理後も強度を維持しているものの、他の試料と比べ、薄く加工するための圧延加工での加工性が悪く、所定の厚みに加工するために、より多くの圧延回数が必要であった。また、比較材Ｎｏ．８は、導電率が９０％ＩＡＣＳを下回っており、導体には不向きである。以上の結果から、Ｚｒの添加量は、０．０１〜０．２０ｗｔ％程度が適切であるといえる。
【００３４】
〔表４〕は上記比較材Ｎｏ．６〜８における耐折性と屈曲特性の結果を示す。
Ｚｒの添加量が低い比較材Ｎｏ．６，７は、屈曲特性は良いものの、耐熱性が無いために熱処理（４５０℃×４時間）により強度が大きく低下し、耐折性が大きくならない。一方、Ｚｒの添加量を大きくした比較材Ｎｏ．８は、耐折性に優れるものの、耐熱性が有りすぎて結晶集合組織の成長が十分に起こらず、屈曲特性が悪くなる。したがって、Ｚｒの添加量は、０．０１〜０．２０ｗｔ％が最適といえる。
【００３５】
【表４】

【００３６】
上記実施例においては、熱処理を４５０℃×４時間としたが、本発明はこの数値に限定されるものではなく、軟化が問題になる３００〜４００℃以上であればよい。また、時間も４時間に限定されるものではなく、数時間の範囲で最良の結果の得られる時間にして実施すればよい。
【００３７】
【発明の効果】
以上より明らかなように、本発明のプリント配線用銅合金箔によれば、Ｚｒが０．０１〜０．２０ｗ％の範囲で銅および不可避不純物の中に含有させた構成により、耐熱性を有し、屈曲特性及び耐折性を兼ね備え、更に導電率の良い配線基板用銅箔を得ることができる。
【００３８】
また、本発明のプリント配線用銅合金箔の製造方法によれば、銅および不可避不純物に０．０１〜０．２０ｗ％のＺｒを含む鋳塊とし、更に圧延及び焼鈍を施して所定の厚さの素材にし、これに対して所定の温度及び時間による熱処理を施す方法にしたので、２５０Ｎ／ｍｍ^２以上の引張強さと９０％ＩＡＣＳ以上の導電率を備えることにより、耐熱性を有し、屈曲特性及び耐折性を兼ね備え、更に導電率の良い配線基板用銅箔を得ることができる。
【図面の簡単な説明】
【図１】屈曲特性を確認するための試験機の構成を示す正面図である。
【図２】耐折性の測定に用いたＭＩＴ試験機の模式的構成図である。
【符号の説明】
１導体
２ａ，２ｂ，２ｃ，２ｄ導体固定部
３振動付加部
４振動発生装置
５ａ，５ｂ支持部
６固定部
７チャック部
１０試験機
２０ＭＩＴ試験機[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a copper alloy foil for printed wiring and a method for manufacturing the same, and more particularly, to a copper alloy foil for printed wiring and a method for manufacturing the same suitable for use as a copper foil such as an FPC (Flexible Print Circuit board). About.
[0002]
[Prior art]
In FPC, COF (Chip On Film: Chip On Film), TAB (Tape Automated Bonding: Tape Automated Bonding), etc. used for mounting semiconductors and electronic devices, wiring is provided on one or both sides of a film-shaped insulator. Copper foil is formed. In the case of FPC, a rolled foil having excellent flexibility is used as the copper foil. The rolled foil is manufactured by elongating the rolled foil by plastic working with a rolling roll, and its material is conventionally made of tough pitch copper (TPC) or oxygen-free copper (OFC). Normally, TPC is used in FPC, and OFC is not used.
[0003]
Rolled copper foil usually has a working degree of at least 80% from final annealing. For this reason, the processed structure which is softened by heating and dense by rolling is coarsened by recrystallization, and the strength is reduced. For example, when 10 μm tough pitch copper having a final working ratio of 90% is used, heat treatment is performed at 150 ° C. for about 30 minutes, and when oxygen-free copper is subjected to heat treatment at 180 ° C. for about 30 minutes, the tensile strength becomes 200 N / mm. ² or less.
[0004]
In the case of FPC using tough pitch copper (TPC), when bonded with a polyimide resin film and cured (heat treatment at 150 to 160 ° C.), recrystallization is performed by softening the copper foil to form a texture. Bending characteristics are improved. However, when oxygen-free copper (OFC) is used as a material, recrystallization is insufficient at a curing temperature, and the bending characteristics cannot be improved. Therefore, conventionally, when the OFC is used, the softening temperature is reduced.
[0005]
On the other hand, printed wiring boards tend to have narrower wiring pitches, and are becoming thinner for fine patterns. In addition, in the case of FPC, TAB, COF, etc., in order to form a fine pattern, instead of the conventional three-layer base material bonded using an adhesive such as a polyimide film, in recent years, dimensional stability, heat resistance (lead) The use of a two-layer substrate excellent in free soldering and bending properties has been increasing. The two-layer base material is subjected to a heat treatment at 300 to 400 ° C. during the manufacturing process and the press bonding of the base material, so that the processing temperature is higher than that of the conventional three-layer base material at 100 to 200 ° C.
[0006]
For example, using oxygen-free copper (OFC) as the material, rolling is performed with a working degree at which the half-softening temperature in isochronous softening characteristics for one hour is 180 ° C. or more, and softening at about 190 ° C. which does not soften at the heating temperature of the adhesive. An oxygen-free copper rolled copper foil capable of obtaining a temperature and a tensile strength of about 42 kg / mm ² has been proposed (for example, see Patent Document 1).
[0007]
Attempts have also been made to achieve an improvement in strength by the composition of the material, for example, containing 0.01 to 0.25% of zirconium (Zr), the balance being copper (electrolytic copper or oxygen-free copper) and There has also been proposed a copper alloy foil in which required conductivity and strength can be obtained by setting the surface roughness to a predetermined value as inevitable impurities (for example, see Patent Document 2). In particular, by specifying the material and composition of the additive and the surface roughness, surface defects can be reduced, and impedance at high frequencies can be reduced.
[0008]
However, the heat resistance of a conventional copper foil formed by TPC or OFC is about 150 to 190 ° C., so that heat treatment at 300 to 400 ° C. softens. As a result, the strength is reduced, the handling property in a line or the like is deteriorated, and further, there are drawbacks such as difficulty in thinning, a problem in crimping property, and insufficient bending resistance. .
[0009]
In recent years, the use environment of FPC, TAB, COF, and the like has become more severe with the miniaturization of portable devices. For example, in the case of the FPC, the bending resistance required for the wiring of the moving part is important. Therefore, a rolled copper foil has been conventionally used as the copper foil, and a bending property is improved by developing a recrystallization texture of the copper foil by heat treatment during curing.
[0010]
[Patent Document 1]
Japanese Patent Publication No. 6-66363 [Patent Document 2]
JP-A-2002-38226
[Problems to be solved by the invention]
However, according to the conventional copper foil for printed wiring, the configuration of Patent Literature 2 is effective in reducing the impedance in a high frequency range due to the reduction of surface defects, and is suitable for use in antennas and the like. Does not consider the required flexibility and folding resistance, and the electrical conductivity is too low for use in FPC. Therefore, it cannot be applied to FPC.
[0012]
In addition, as described above, when the bending characteristics are improved by developing the recrystallization texture of the copper foil by the heat treatment during curing, a decrease in the strength of the copper foil occurs. In addition, a problem arises in that the folding resistance is reduced.
[0013]
In semiconductors, electronic circuits, electronic devices, and the like, further miniaturization and higher mounting are required, and copper foil for printed wiring copper foil that has both bending characteristics and folding resistance is required. Heretofore, there has been no copper foil for printed wiring satisfying this requirement.
[0014]
Accordingly, an object of the present invention is to provide a copper alloy foil for printed wiring, which is excellent in heat resistance, flexibility, folding resistance, and conductivity, and a method of manufacturing the same.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has, as a first feature, a weight ratio of Zr in the range of 0.01 to 0.20 w% in terms of a component of the additive element, and the balance being copper and unavoidable impurities. A copper alloy foil for printed wiring, which has a tensile strength of 400 N / mm ² or more and a conductivity of 90% IACS or more.
[0016]
According to this configuration, since Zr is contained in copper and inevitable impurities in a range of 0.01 to 0.20 w%, copper having a tensile strength of 400 N / mm ² or more and a conductivity of 90% IACS or more is provided. An alloy foil is obtained, whereby a copper alloy foil for printed wiring having temperature resistance, high flexibility, high folding resistance, and high conductivity can be obtained.
[0017]
In order to achieve the above object, the present invention provides, as a second feature, a casting method in which the weight ratio of Zr is 0.01 to 0.20 w% in terms of the component of the additional element, and the balance is copper and unavoidable impurities. An ingot is prepared, the ingot is subjected to hot rolling, cold rolling, and annealing as appropriate to be processed into a material having a predetermined thickness, and the material is subjected to a heat treatment at a predetermined temperature and a predetermined time, and is subjected to 250 N / A method for producing a copper alloy foil for printed wiring, wherein the material is subjected to a heat treatment at a predetermined temperature and for a predetermined time so that the material has a tensile strength of at least ² mm and a conductivity of at least 90% IACS. provide.
[0018]
According to this method, a material having a predetermined thickness is rolled and annealed to obtain a material having a predetermined thickness based on an ingot containing 0.01 to 0.20 w% of Zr as inevitable impurities. , A copper alloy foil for printed wiring having a tensile strength of 250 N / mm ² or more and a conductivity of 90% IACS or more can be manufactured, whereby the temperature resistance, high flexibility and high bending resistance can be obtained. , And a copper alloy foil for printed wiring having high conductivity.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
In the copper alloy foil for printed wiring according to the embodiment of the present invention, the weight ratio of Zr (zirconium) is set to 0.01 to 0.20 w% in the proportion of the additive element, and the balance is copper and inevitable impurities. Thus, it is intended to obtain a tensile strength of 400 N / mm ² or more and a conductivity of 90% IACS or more. By setting the content of Zr to 0.01 to 0.20 w%, P and S contained in a solid solution state in copper are precipitated, and the heat resistance is improved. Further, the copper alloy foil for printed wiring is subjected to a heat treatment in a final step to obtain a tensile strength of 250 N / mm ² or more.
[0020]
Here, if the addition amount of Zr is 0.015% by weight or less, the amount of solid solution becomes insufficient, and it is not possible to prevent the crystal grains from becoming coarse during the heat treatment. On the other hand, when Zr exceeds 0.20 wt%, the conductivity decreases as well as the workability, and it is not suitable for a conductor of a printed wiring board.
[0021]
Next, examples of the present invention will be described. In the present example, oxygen-free copper having an oxygen content of 10 ppm was used as a base material, Zr was added to the base material, and the resulting material was melt-cast. 1 to 5 were produced. Here, the sample No. 1 to 5 are 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, and 0.20 wt% of Zr, respectively.
[0022]
Next, each of the ingots was hot-rolled, processed into a material having a thickness of 12 mm, processed by a method of repeating cold rolling and annealing, and cold-rolled to a thickness of 12 μm to obtain a sample. After heat-treating the above sample in a reducing atmosphere at 450 ° C. for 4 hours, the characteristics were confirmed. The characteristics shown in [Table 1] were obtained.
[0023]
[Table 1]

[0024]
As shown in [Table 1], it was confirmed that all of the samples could obtain sufficient strength against the heat treatment at 450 ° C. for 4 hours. A two-layer substrate was manufactured using this copper foil. Sample No. of [Table 1]. In any of the cases 1 to 5, a two-layer base material free of wrinkles and the like on the copper foil could be obtained.
[0025]
FIG. 1 shows a configuration of a tester for confirming bending characteristics. The tester 10 has conductor fixing portions 2a, 2b, 2c, and 2d for fixing both ends of the conductor 1 having an inverted W shape, and vibrates the conductor 1 while being in contact with the center of the conductor 1. The vibration applying unit 3 includes a vibration generating unit 4 that transmits the generated vibration to the vibration applying unit 3, and supporting units 5 a and 5 b that support the vibration generating device 4. .
[0026]
Sample No. of [Table 1]. About 1-5, the bending characteristic was confirmed using the test machine of FIG. The test conditions were as follows: test piece width: 12.7 mm, test piece length: 200 mm, test piece collection direction: rolling direction, radius of curvature r: 2.5 mm, vibration stroke: 10 mm, vibration speed: 1500 times / min. In addition, the bending resistance was measured by an MIT tester as shown in FIG. 2 defined by the IPC standard.
[0027]
FIG. 2 shows an MIT tester used for the measurement of folding resistance. The MIT tester 20 includes a fixing portion 6 that fixes one end of the conductor 1 and a chuck portion 7 that bends a set angle while holding the other end of the conductor 1. Here, the test conditions of the MIT tester 20 were set at an angle of 135 ° and the bending R was 2 mm. That is, the chuck portion 7 is set to a bending range of 135 °, and an operation of holding the other end of the conductor 1 upward by the fixing portion 6 while holding the other end by the chuck portion 7 and bending the conductor 1 to 135 °. Measured repeatedly. [Table 2] was obtained as the measurement result.
[0028]
[Table 2]

[0029]
[Table 2] shows the measurement results of the folding resistance. This measurement was performed by applying a rolled copper foil (rolled copper foil only) and a heat treatment at 450 ° C. for 4 hours. Referring to [Table 2], it was confirmed that the heat-treated one improved the bending property by about 10% and further improved the folding resistance by about 50% as compared with the copper foil after rolling.
[0030]
As is clear from [Table 1] and [Table 2], according to the example of the present invention, heat resistance is improved by adding 0.01 to 0.20 w% of Zr to oxygen-free copper, As a result, the flexibility and folding resistance have been improved, and the electrical conductivity required for the FPC can be secured. Furthermore, by performing a predetermined heat treatment, the flexibility and folding resistance can be further improved.
[0031]
The present inventors have compared Comparative Example Nos. 6 to 8 were prepared for comparative study. Here, ordinary oxygen-free copper was used as a comparative material No. No. 6, a material to which a small amount of Zr was added (0.005 wt%) was used as Comparative Material No. No. 7, a material to which a large amount of Zr was added (0.3%) was used as a comparative material No. And 8. The measurement results in this comparative example are shown in [Table 3].
[0032]
[Table 3]

[0033]
With reference to [Table 3], Comparative Material No. In Nos. 6 and 7, the strength after the heat treatment was lowered, and the strength was not sufficient. In addition, the comparative material No. Sample No. 8 maintains strength after heat treatment, but has poor workability in rolling to make it thinner than other samples, and requires a larger number of rolling times to make it into a predetermined thickness Met. In addition, the comparative material No. 8 has an electrical conductivity below 90% IACS and is not suitable for conductors. From the above results, it can be said that the addition amount of Zr is appropriately about 0.01 to 0.20 wt%.
[0034]
[Table 4] shows the comparative material No. The results of the bending resistance and bending characteristics in Nos. 6 to 8 are shown.
Comparative material No. Zr with a low addition amount of Zr. Nos. 6 and 7 have good bending properties, but do not have heat resistance, so that the heat treatment (450 ° C. × 4 hours) greatly reduces strength and does not increase folding resistance. On the other hand, the comparative material No. No. 8 is excellent in bending resistance, but has too high heat resistance to cause sufficient growth of the crystal texture, resulting in poor bending characteristics. Therefore, it can be said that the optimum amount of Zr added is 0.01 to 0.20 wt%.
[0035]
[Table 4]

[0036]
In the above embodiment, the heat treatment was performed at 450 ° C. for 4 hours. However, the present invention is not limited to this value, and may be 300 to 400 ° C. or more where softening becomes a problem. Further, the time is not limited to 4 hours, and the time may be set within a range of several hours to obtain the best result.
[0037]
【The invention's effect】
As is clear from the above, according to the copper alloy foil for printed wiring of the present invention, heat resistance is obtained due to the configuration in which Zr is contained in copper and inevitable impurities in the range of 0.01 to 0.20 w%. In addition, it is possible to obtain a copper foil for a wiring board which has both bending characteristics and folding resistance and has a higher conductivity.
[0038]
Further, according to the method for producing a copper alloy foil for printed wiring of the present invention, an ingot containing 0.01 to 0.20 w% of Zr in copper and inevitable impurities is further rolled and annealed to a predetermined thickness. And a heat treatment at a predetermined temperature and for a predetermined time. Therefore, by providing a tensile strength of 250 N / mm ² or more and an electrical conductivity of 90% IACS or more, the material has heat resistance and bending. It is possible to obtain a copper foil for a wiring board which has both characteristics and folding resistance, and which has better conductivity.
[Brief description of the drawings]
FIG. 1 is a front view showing a configuration of a tester for checking a bending characteristic.
FIG. 2 is a schematic configuration diagram of an MIT tester used for measuring folding resistance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conductor 2a, 2b, 2c, 2d Conductor fixing part 3 Vibration adding part 4 Vibration generators 5a, 5b Support part 6 Fixing part 7 Chuck part 10 Testing machine 20 MIT testing machine

Claims

The weight ratio of Zr is in the range of 0.01 to 0.20 w% in the ratio of the components of the additional elements, the balance is copper and inevitable impurities, the tensile strength is 400 N / mm ² or more, and the conductivity is 90%. % IACS or more, a copper alloy foil for printed wiring.

The copper alloy foil for printed wiring according to claim 1, wherein the copper is oxygen-free copper.

The copper alloy foil for printed wiring according to claim 1 or 2, wherein a heat treatment is performed in a final step to make the tensile strength 250 N / mm ² or more.

The copper alloy foil for printed wiring according to claim 3, wherein the heat treatment is performed at a temperature of 300 ° C. or more for several hours.

The weight ratio of Zr is 0.01 to 0.20 w% in proportion of the component of the additional element, and the remainder is copper and an ingot that is an unavoidable impurity is prepared.
The ingot is hot-rolled, cold-rolled, and appropriately processed by annealing to a material having a predetermined thickness,
Producing a copper alloy foil for printed wiring, wherein the material is subjected to a heat treatment at a predetermined temperature and for a predetermined time so as to have a tensile strength of 250 N / mm ² or more and a conductivity of 90% IACS or more. Method.