JP3928392B2 - Method for manufacturing printed wiring board - Google Patents

Method for manufacturing printed wiring board Download PDF

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Publication number
JP3928392B2
JP3928392B2 JP2001278325A JP2001278325A JP3928392B2 JP 3928392 B2 JP3928392 B2 JP 3928392B2 JP 2001278325 A JP2001278325 A JP 2001278325A JP 2001278325 A JP2001278325 A JP 2001278325A JP 3928392 B2 JP3928392 B2 JP 3928392B2
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Japan
Prior art keywords
copper
etching
printed wiring
wiring board
copper foil
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JP2001278325A
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Japanese (ja)
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JP2003086938A (en
Inventor
健次 高井
直之 浦崎
豊樹 伊藤
茂晴 有家
昭士 中祖
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Showa Denko Materials Co Ltd
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Hitachi Chemical Co Ltd
Showa Denko Materials Co Ltd
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Description

【0001】
【発明の属する技術分野】
本発明は、プリント配線板の製造方法に関する。
【0002】
【従来の技術】
近年、電子機器の小型、軽量、高速化の要求が高まり、プリント配線板の高密度化が進んでいる。従来の、銅をエッチングすることで作製するプリント配線板は、サイドエッチングの影響で配線の微細化には限界があり、基板の高密度化には限界があった。そこで近年は電気めっきを用いたセミアディティブ法によるプリント配線板の製造方法が注目されている。このセミアディティブ法は特開平11−186716にあるように回路を形成したい樹脂表面にレーザー等でIVHとなる穴を形成した後に、化学粗化やプラズマ処理等により数μmの凹凸を樹脂上に形成し、Pd触媒を付与し、1μm程度の無電解めっきを行い、パターン電気めっきレジストを形成し、パターン電気めっきにより回路形成を行った後にレジスト及び余分な個所の無電解めっきを除去する手法である。
【0003】
【発明が解決しようとする課題】
しかし、上記のセミアディティブ法により回路形成を行う場合、絶縁樹脂上に直接無電解銅めっき層を形成するためのPd触媒を付与するために、その後の工程でPdを除去することが難しい。絶縁樹脂上にPdが残存していると、絶縁信頼性の低下等の不具合や樹脂上にNi/Auめっきが析出してしまう等の不具合が生じる。
【0004】
また、密着性向上のために化学粗化やプラズマ処理等により数μmの凹凸を絶縁樹脂上に形成する必要があるが、粗化が不充分で導体回路が剥離するような不具合が発生し易い。
【0005】
さらに、銅箔付層間絶縁樹脂上にセミアディティブ法により回路形成を行う場合、導体回路の過剰な溶解が避けられず、導体回路のトップ幅が著しく細くなってしまうという欠点がある。
【0006】
本発明は、上記不具合を発生し難くし、導体回路間のショート不良が少なく、導体回路の溶解を抑制し、回路形成性のよいプリント配線板の製造方法を提供するものである。
【0007】
【課題を解決するための手段】
上記課題を解決するために、本発明は、導体回路を有する内層回路基板の上下面に厚み5μm以下の銅箔を貼り付けた層間絶縁樹脂を積層する工程と、内層回路基板に層間接続のためのIVH(インタースティシャルバイアホール)を形成する工程と、給電層として薄付け無電解銅めっきを行い、電気めっきレジストを形成した後に電気銅めっきを行う工程と、電気めっきレジストを除去し、パターン部以外の銅をエッチング除去することで導体回路パターンを形成する工程と、を少なくとも有するプリント配線板の製造方法をその特徴としている。また、上記積層工程における内層回路基板の上下面にプリプレグを介して厚み5μm以下の銅箔を積層してもよい。
【0008】
この特徴によれば、触媒は絶縁樹脂上ではなく銅箔に吸着することになるため触媒の除去が容易となり、さらに、無電解銅めっき層は銅箔上に形成されることになるため、絶縁樹脂上の粗化を行う必要がなくなる。
【0009】
また、本発明は、パターン部以外の銅をエッチング除去する際の電気銅めっきのエッチング速度が銅箔のエッチング速度の80%以下であることを特徴としている。さらに、このようなエッチング速度のコントロールのために、層間絶縁樹脂またはプリプレグに貼り付ける厚み5μm以下の銅箔として電気銅めっき時の電流密度よりも大きい電流密度で作製された銅箔を用いること、また、エッチング除去にハロゲンを除く酸と過酸化水素を主成分とするエッチング液を用いることも本発明の特徴としている。
【0010】
一般的に、高電流密度で作製される電解銅と低電流密度で作製される電解銅ではその結晶構造が異なる。また、主成分が上記のようなエッチング液は、拡散律速性が弱く反応律速であるため、銅の結晶構造によりエッチング速度が変化する。すなわち、高密度電流で作製される本発明の銅箔は容易にエッチングされ、より低密度電流で施される本発明の電気銅めっきはエッチングされ難くなるため、パターン部以外の銅が素早く除去され、導体回路のトップ幅の著しい減少は抑制されることとなり、回路形成性のよいプリント配線板を製造することが可能となる。特に、エッチング液の主成分であるハロゲンを除く酸として硫酸を用いた場合には大変良好な微細配線形成性をもたらす。また、結晶構造の差異によるエッチング速度の差は、低温のエッチング時に顕著であるため、エッチング液の温度はなるべく低温にして行った方が導体回路の過剰な溶解を抑制し、より良好な微細配線形成を為すことになる。
【0011】
また、本発明は、導体回路の最表面に無電解Ni/Auめっき層を形成する工程を含むことをもその特徴としている。
【0012】
以上のような本発明の特徴により、信頼性が高く、回路形成性のよいプリント配線板を提供することを可能した。
【0013】
尚、本発明で用いる用語「電流密度」は、電極の単位面積当たりの電流の大きさを表しており、当業者が理解している通常の意味で使用している。
【0014】
【発明の実施の形態】
以下、本発明によるプリント配線板の製造方法を図1を用いてさらに詳細に説明する。
【0015】
まず、絶縁基材を加工して内層回路基板を作製する。絶縁基材表面への導体回路の形成は、銅張積層板をエッチングして行うサブトラクティブ法が一般的であるが、特に限定されない。さら絶縁基材にスルーホール等の貫通孔を形成し、内層導体回路を形成し、内層回路基板を得る。図1(a)では単層の両面板であるが、この内層回路基板は多層板でもよい。
【0016】
次に内層回路基板の表面の内層銅パターンを粗面化し、この銅パターンの上に形成される層間樹脂絶縁層との密着性を向上させる必要がある。具体的には内層銅パターンの上に針状の無電解めっきを形成する方法や内層銅パターンを酸化(黒化)―還元処理する方法、内層銅パターンをエッチングする方法等がある。
【0017】
次に、上記のようにして得られた内層回路基板上に図1(b)に示す様に銅箔付層間絶縁樹脂をラミネートとする。層間絶縁樹脂としてはエポキシ系樹脂やポリイミド系樹脂を主成分として含むものが好ましいが、他にもアクリル樹脂、ポリイミド樹脂、ベンゾシクロブテン樹脂、フッ素樹脂、シアネート樹脂、PPE等や、その含有物でもよい。銅箔付層間絶縁樹脂をラミネートとするかわりにプリプレグを介して銅箔を積層してもよい。層間樹脂絶縁層の厚みは10から100μm程度、望ましくは20から60μmがよく、銅箔の厚みは5μm以下が好適である。また、ここで用いる銅箔は、電気銅めっき時の電流密度より大きい電流密度で作製されたものであればよいが、好ましくは5A/dm2以上の電流密度で作製されたものを使用する。銅箔作製時の電流密度が低いと後のエッチング工程でエッチング速度が遅いという不具合が発生し、回路形成に支障をきたす。
【0018】
次いで図1(c)に示す様に銅箔の上から層間樹脂絶縁層にIVHを形成する。IVHを形成する方法としては、レーザーを用いるのが好適である。ここで用いることが出来るレーザーとしては、CO2やCO、エキシマ等の気体レーザーやYAG等の固体レーザーがある。CO2レーザーは容易に大出力を得られる事からφ50μm以上のIVHの加工に適している。φ50μm以下の微細なIVHを加工する場合は、より短波長で集光性のよいYAGレーザーが適している。
【0019】
次いで過マンガン酸塩、クロム酸塩、クロム酸のような酸化剤を用いてIVH内部の樹脂残さの除去を行う。
【0020】
次いで銅箔上及びIVH内部に触媒核を付与する。触媒核の付与には、貴金属イオンやパラジウムコロイドを使用する。特にパラジウムコロイドを使用するのが安価で好ましい。
【0021】
次に図1(d)に示すように、触媒核を付与した銅箔上及びIVH内部に薄付けの無電解めっき層を形成する。この無電解めっきには、硫酸銅、ホルマリン、錯化剤、水酸化ナトリウム等を主成分とする市販のものが使用でき、例えば、CUST2000(日立化成工業株式会社製、商品名)やCUST201(日立化成工業株式会社製、商品名)等が挙げられるが、特に限定されるものではない。めっきの厚さは次の電気銅めっきを行うことができる厚さであればよく、好ましくは0.1〜1μmである。
【0022】
次に図1(e)に示すように無電解めっき層上のIVH上と導体回路となる以外の個所に電気めっきレジストを形成する。電気めっきレジストの厚さは、その後めっきする導体の厚さと同程度か、より厚い膜厚にするのが好適である。電気めっきレジストに使用できる樹脂には、PMER P−LA900PM(東京応化株式会社製、商品名)のような液状レジストや、HW−425(日立化成工業株式会社、商品名)、RY−3025(日立化成工業株式会社、商品名)等のドライフィルムがある。
【0023】
次に図1(f)に示すように電気銅めっき層を形成する。電気銅めっきには、通常プリント配線板で使用される硫酸銅電気めっきやピロリン酸電気めっきが使用できる。電気銅めっきの厚さは、導体回路として使用できればよく、1〜100μmの範囲であることが好ましく、5〜50μmの範囲であることがより好ましい。また、電気銅めっき層形成時の電流密度は厚み5μm以下の銅箔作製時の電流密度よりも小さければよいが、好ましくは0.5A/dm2以上5A/dm2以下である。電気銅めっき層形成時の電流密度が銅箔作製時の電流密度よりも高いと後のエッチング工程で過剰に溶解されやすくなってしまい良好な回路形成を為すのに支障をきたす。
【0024】
次にアルカリ性剥離液や硫酸あるいは市販のレジスト剥離液を用いて電気めっきレジストの剥離を行う。
【0025】
次にパターン部以外の銅をハロゲン以外の酸及び過酸化水素を主成分とするエッチング液を用いて除去することで回路形成が終了する。(図1(g))本発明のエッチング液は上記主成分に加えて溶媒、添加剤からなる溶液であり、溶媒としては、コスト、取り扱い性、安全性の面から水が好ましく用いられ、水にはアルコール等が添加されていても構わない。また、添加剤としては過酸化水素の安定剤等が添加されうる。さらに、本発明の主成分であるハロゲン以外の酸としては、硫酸、硝酸等が挙げられ、好ましくは、硫酸が用いられる。
【0026】
このような本発明のエッチング液を用いてパターン部以外の銅をエッチング除去し、設計通りの導体回路のトップ幅、ボトム幅を得るためには電気銅めっきのエッチング速度が銅箔のエッチング速度の80%以下であることが好ましい。
【0027】
また、ハロゲン以外の酸として硫酸を用いる場合、エッチング液の主成分の濃度として、10〜300g/Lの硫酸および10〜200g/Lの過酸化水素水を用いることが好ましい。上記濃度域以下の濃度ではエッチング速度が遅いために作業性が悪く、上記濃度域以上の濃度ではエッチング速度が速いためにエッチング量のコントロールが難しい。また、銅箔のエッチング速度としては1〜15μm/分となるようにコントロールすることが作業性の面から好ましい。また、結晶構造の差異によるエッチング速度の差はエッチング液の温度に依存するため、エッチング除去の際のエッチング液の温度は20〜50℃とすることが好ましく、20〜40℃とすることがより好ましい。さらにエッチング時間としては、所望の導体回路幅が形成されるような時間を実験により適宜求めればよいが、作業性、エッチングの均一性等のために10秒〜10分の範囲であることが好ましい。
【0028】
さらに、上記で形成された導体回路パターン上に金めっき処理を行うことも出来る。金めっき層の形成方法としては、SA―100(日立化成工業株式会社製、商品名)のような活性化処理液で導体回路界面の活性化処理を行った後、NIPS―100(日立化成工業株式会社製、商品名)のような無電解ニッケルめっき液により1〜10μm程度のニッケル層を形成し、このニッケル層の上面にHGS―100(日立化成工業株式会社製、商品名)のような置換金めっき液により0.01〜0.1μm程度の金めっき下地層を形成し、さらにその上面にHGS―2000(日立化成工業株式会社製、商品名)のような無電解金めっき液により0.1〜1μm程度の金めっき仕上げ層を形成する方法が挙げられるが、もちろんこれに限定されず、通常行われうる金めっき処理に適した方法であればよい。
【0029】
【実施例】
実施例1
図1(a)に示すように、絶縁基材に、厚さ18μmの銅箔を両面に貼り合わせた厚さ0.2mmのガラス布基材エポキシ銅張積層板であるMCL−E−679(日立化成工業株式会社製、商品名)を用い、その不要な箇所の銅箔をエッチング除去し、スルーホール12を形成して、内層導体回路10を形成し、内層回路基板11を作製した。
【0030】
内層回路基板11の内層導体回路10の処理を、MEC etch BOND CZ−8100(メック株式会社製、商品名)を用い、液温35℃、スプレー圧0.15MPの条件で、スプレー噴霧処理し、銅表面を粗面化して、粗さ3μm程度の凹凸を作り、MEC etch BOND CL−8300(メック株式会社製、商品名)を用いて、液温25℃、浸漬時間20秒間の条件で浸漬して、銅表面に防錆処理を行った。
【0031】
図1(b)に示すように、内層回路基板11の両面に、10A/dm2の電流密度で作製した3μm銅箔13に接着剤を塗布したMCF−7000LX(日立化成工業株式会社製、商品名)を、170℃、30kgf/cm2の条件で60分加熱加圧ラミネートし、厚さ40μmの層間絶縁樹脂層14を形成した。
【0032】
図1(c)に示すように、銅箔13上から炭酸ガスインパクトレーザー穴あけ機L−500(住友重機械工業株式会社製、商品名)により、直径80μmの非貫通孔であるIVH15をあけ、過マンガン酸カリウム65g/Lと水酸化ナトリウム40g/Lの混合水溶液に、液温70℃で20分間浸漬し、スミアの除去を行った。
【0033】
その後、パラジウム溶液であるHS−202B(日立化成工業株式会社製、商品名)に25℃で15分間浸漬し、触媒を付与した後、CUST−201(日立化成工業株式会社製、商品名)を使用し、液温25℃、30分の条件で無電解銅めっきを行い、図1(d)に示すように厚さ0.3μmの無電解銅めっき層16を形成した。
【0034】
図1(e)に示すように、ドライフィルムフォトレジストであるRY−3025(日立化成工業株式会社製、商品名)を、無電解めっき層16の表面にラミネートし、電気銅めっきを行う箇所をマスクしたフォトマスクを介して紫外線を露光し、現像して電気めっきレジスト17を形成した。
【0035】
図1(f)に示すように、硫酸銅浴を用いて、液温25℃、電流密度1.0A/dm2の条件で、電気銅めっきを20μmほど行い、回路導体幅/回路導体間隔(L/S)=35/25μmとなるように電気銅めっき層18を形成した。
【0036】
次に図1(g)に示すように、レジスト剥離液であるHTO(ニチゴー・モートン株式会社製、商品名)で電気めっきレジスト17の除去を行った後に主成分として硫酸20g/L、過酸化水素10g/Lの組成のエッチング液を用いてパターン部以外の銅をエッチング除去した。エッチング時は基板を片面1dm2の小片に切断した後、1Lビーカーに入れ、マグネティックスターラーを用いて40℃で5分間エッチングを行った。
【0037】
最後に表1に示す条件で導体回路にNi/Auめっき層19を形成した(図1(h))。
【0038】
【表1】

Figure 0003928392
【0039】
実施例2
電気銅めっきを3A/dmの電流密度で行った他は実施例1と同様に基板を作製した。
【0040】
実施例3
エッチング液の主成分の組成を硫酸20g/L、過酸化水素40g/Lとし、エッチング時間を60秒とした他は実施例1と同様に基板を作製した。
【0041】
実施例4
電気銅めっきを3A/dmの電流密度で行った他は実施例3と同様に基板を作製した。
【0042】
実施例5
エッチング液の主成分の組成を硫酸20g/L、過酸化水素40g/Lとし、エッチング温度を30℃、エッチング時間を100秒とした他は実施例1と同様に基板を作製した。
【0043】
実施例6
電気銅めっきを3A/dmの電流密度で行った他は実施例5と同様に基板を作製した。
【0044】
実施例7
エッチング液の主成分の組成を硝酸20g/L、過酸化水素10g/Lとした他は実施例1と同様に基板を作製した。
【0045】
実施例8
エッチング液の主成分の組成を硫酸200g/L、過酸化水素200g/Lとした他は実施例1と同様に基板を作製した。
【0046】
比較例1
エッチング液の主成分の組成を硫酸20g/L、過酸化水素20g/Lとし、エッチング温度を60℃、エッチング時間を100秒とした他は実施例1と同様に基板を作製した。
【0047】
比較例2
パターン部以外の銅のエッチングにFeCl水溶液30g/Lを用いた他は実施例1と同様に基板を作成した。
【0048】
比較例3
パターン部以外の銅のエッチングにCuCl水溶液40g/L、塩酸30g/Lを用いた他は実施例1と同様に基板を作成した。
【0049】
比較例4
パターン部以外の銅のエッチングに塩化テトラアンミン銅(II)を主成分とするAプロセス液(メルテックス株式会社製、商品名)を用いて30℃で30秒間エッチングを行った他は実施例1と同様に基板を作成した。
【0050】
比較例5
図2(a)に示すように、絶縁基材に、厚さ18μmの銅箔を両面に貼り合わせた厚さ0.2mmのガラス布基材エポキシ銅張り積層板であるMCL−E−679(日立化成工業株式会社製、商品名)を用い、その不要な箇所の銅箔をエッチング除去し、スルーホール22を形成して、内層導体回路20を形成し、内層回路基板21を作製した。
【0051】
その内層回路基板21の内層導体回路20の処理を、MEC etch BONDCZ−8100(メック株式会社製、商品名)を用い、液温35℃、スプレー圧0.15MPの条件で、スプレー噴霧処理し、銅表面を粗面化して、粗さ3μm程度の凹凸を作り、MEC etch BOND CL−8300(メック株式会社製、商品名)を用いて、液温25℃、浸漬時間20秒間の条件で浸漬して、銅表面に防錆処理を行った。
【0052】
図2(b)に示すように、内層回路基板21の両面に、絶縁接着剤であるBL−9700(日立化成工業株式会社製、商品名)を厚さ40μmに塗布し、170℃で60分加熱し、層間絶縁樹脂層24を形成した。
【0053】
図2(c)に示すように、炭酸ガスインパクトレーザー穴あけ機L−500(住友重機械工業株式会社製、商品名)により、直径80μmの非貫通孔であるIVH25をあけ、過マンガン酸カリウム65g/Lと水酸化ナトリウム40g/Lの混合水溶液に、液温70℃で20分間浸漬し、スミアの除去を行うと同時に表面に微細な凹凸を作った。
【0054】
次に、超音波洗浄装置PUC−0586(東京超音波技研株式会社製、商品名)を用いて、洗浄液イオン交換水、発信周波数25kHz、出力600Wの条件で5分間超音波処理を行い、基板表面の脆弱層の除去を行った。
【0055】
その後、パラジウム溶液であるHS−202B(日立化成工業株式会社製、商品名)に、25℃で15分間浸漬し、触媒を付与した後、CUST−201(日立化成工業株式会社製、商品名)を使用し、液温25℃、30分の条件で無電解銅めっきを行い、図2(d)に示すように厚さ0.3μmの無電解銅めっき層26を形成した。
【0056】
図2(e)に示すように、ドライフィルムフォトレジストであるRY−3025(日立化成工業株式会社製、商品名)を、無電解銅めっき層26の表面にラミネートし、電気銅めっきを行う箇所をマスクしたフォトマスクを介して紫外線を露光し、現像して電気めっきレジスト27を形成した。
【0057】
図2(f)に示すように、硫酸銅浴を用いて、液温度25℃、電流密度1.0A/dm2の条件で、電気銅めっきを20μmほど行い、回路導体層/回路導体間隔(L/S)=30/30μmとなるように電気銅めっき層28を形成した。
【0058】
次に、図2(g)に示すように、レジスト剥離液であるHTO(ニチゴー・モートン株式会社製、商品名)で電気めっきレジスト27の除去を行った後、主成分として硫酸20g/L、過酸化水素10g/Lの組成のエッチング液を用いてパターン部以外の銅をエッチング除去した。エッチング時は基板を片面1dm2の小片に切断した後、1Lビーカーに入れ、40℃まで加温した後マグネティックスターラーにて1分間エッチングを行った。
【0059】
最後に、図2(h)に示すように実施例1と同様の手法でNi/Auめっき層29を形成することで基板を作製した。
【0060】
比較例6
パターン部以外の銅のエッチングにFeCl水溶液30g/Lを用いた他は比較例5と同様に基板を作成した。
【0061】
比較例7
パターン部以外の銅のエッチングにCuCl水溶液40g/L、塩酸30g/Lを用いた他は比較例5と同様に基板を作成した。
【0062】
比較例8
パターン部以外の銅のエッチングに塩化テトラアンミン銅(II)を主成分とするAプロセス液(メルテックス株式会社製、商品名)を用いて30℃で30秒間エッチングを行った他は比較例5と同様に基板を作成した。
【0063】
比較例9
エッチング液の主成分の組成を塩酸40g/L、過酸化水素10g/Lとした他は実施例1と同様に基板を作製した。
【0064】
比較例10
エッチング液の主成分の組成を硫酸3g/L、過酸化水素3g/Lとした他は実施例1と同様に基板を作製した。
【0065】
比較例11
銅箔作製時の電流密度を5A/dm2、電気銅めっき時の電流密度を7A/dm2とした他は実施例1と同様に基板を作製した。
【0066】
実施例1〜8、比較例1〜11で作製した基板の導体トップ幅、導体ボトム幅、回路間エッチング残り、回路間Auめっき析出を評価した結果を表2に示す。回路間エッチング残りや回路間Auめっき析出は図3のように回路からすそをひくような形状で発生することが多い。そこで、回路間のトップとボトムの差を2で割った値をすその長さとし、この値が5μm以上であれば回路間エッチング残りありとした(回路間Auめっき析出の測定方法も同様)。導体および回路間のトップ幅およびボトム幅は基板を光学顕微鏡で上部から撮影し、画像処理を行ったデータをもとに任意に20点測定し、平均を算出したものである。
【0067】
【表2】
Figure 0003928392
【0068】
実施例1〜8で作製した基板は、導体トップ幅がほぼ設計値通りに仕上がっており、トップ幅とボトム幅の差もほとんどなく回路形成性は良好であった。一方、比較例1は、エッチング液の温度を高めに設定したために銅箔と導体回路のエッチング速度にほとんど差が生じず、導体回路が過剰に溶解されてしまう不具合が発生した。比較例2〜4、6〜9は拡散律速性エッチング液を使っているので液当たりのよい導体トップの部分が過剰に溶解されてしまい、回路間エッチング残り、回路間Auめっき析出が発生しやすいことが分かった。比較例5はPd除去が不十分になりやすく回路間Auめっき析出が発生しやすいことが分かった。比較例10は、エッチング液の主成分濃度が薄いため設計値通りに回路形成されるまでのエッチング時間が長すぎ、作業性が悪い。比較例11は、電気銅めっき時の電流密度が銅箔作製時の電流密度の値より大きいためにパターン部以外の銅と導体トップ部分のエッチング速度に殆ど差が生じず、導体回路が過剰にエッチングされてしまった。
【0069】
本発明は上記に複数の実施の形態を示したが、この記載が本発明を限定するものであると理解すべきではない。この開示から当業者にはここでは記載していない様々な代替実施の形態、実施例、運用技術が明らかとなろう。したがって、本発明の技術的範囲は上記の説明から妥当な特許請求に係る発明特定事項によってのみ定められるものである。
【0070】
【発明の効果】
以上、本発明によれば、導体回路間のショート不良が少なく、回路形成性のよいプリント配線板を作製することが出来る。
【図面の簡単な説明】
【図1】 本発明によるプリント配線板の製造工程の一例を示す断面図である。
【図2】 比較例5のプリント配線板の製造工程を示す断面図である。
【図3】 回路間エッチング残りまたは回路間Auめっき析出を示す回路の断面図である。
【符号の説明】
10、20 内層導体回路
11、21 内層回路基板
12、22 スルーホール
13 銅箔
14、24 層間絶縁樹脂層
15、25 IVH
16、26 無電解銅めっき層
17、27 電気めっきレジスト
18、28 電気銅めっき層
19、29 Ni/Auめっき層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a printed wiring board.
[0002]
[Prior art]
In recent years, there has been an increasing demand for smaller, lighter, and faster electronic devices, and the density of printed wiring boards has been increasing. A conventional printed wiring board manufactured by etching copper has a limit in miniaturization of wiring due to the influence of side etching, and has a limit in increasing the density of the substrate. Therefore, in recent years, a method for producing a printed wiring board by a semi-additive method using electroplating has attracted attention. In this semi-additive method, as described in JP-A-11-186716, after forming a hole that becomes IVH with a laser or the like on the surface of the resin on which a circuit is to be formed, an unevenness of several μm is formed on the resin by chemical roughening or plasma treatment. In this method, a Pd catalyst is applied, electroless plating of about 1 μm is performed, a pattern electroplating resist is formed, a circuit is formed by pattern electroplating, and then the electroless plating at the excess portion is removed. .
[0003]
[Problems to be solved by the invention]
However, when circuit formation is performed by the semi-additive method described above, it is difficult to remove Pd in subsequent steps in order to provide a Pd catalyst for forming an electroless copper plating layer directly on the insulating resin. If Pd remains on the insulating resin, problems such as a decrease in insulation reliability and problems such as Ni / Au plating being deposited on the resin occur.
[0004]
Further, in order to improve adhesion, it is necessary to form unevenness of several μm on the insulating resin by chemical roughening, plasma treatment or the like. However, the roughening is insufficient and the trouble that the conductor circuit is peeled off easily occurs. .
[0005]
Furthermore, when a circuit is formed on the interlayer insulating resin with copper foil by the semi-additive method, there is a drawback that excessive melting of the conductor circuit is unavoidable and the top width of the conductor circuit becomes extremely thin.
[0006]
The present invention provides a method for manufacturing a printed wiring board that is less likely to cause the above-described problems, has few short-circuit defects between conductor circuits, suppresses dissolution of conductor circuits, and has good circuit formability.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a step of laminating an interlayer insulating resin having a copper foil of 5 μm or less on the upper and lower surfaces of an inner layer circuit board having a conductor circuit, and an interlayer connection to the inner layer circuit board. Forming an IVH (interstitial via hole), performing a thin electroless copper plating as a power supply layer, forming an electroplating resist, and then performing an electrocopper plating, removing the electroplating resist, And a step of forming a conductor circuit pattern by etching away copper other than the portion of the printed wiring board. Moreover, you may laminate | stack copper foil with a thickness of 5 micrometers or less through the prepreg on the upper and lower surfaces of the inner-layer circuit board in the said lamination process.
[0008]
According to this feature, the catalyst is adsorbed not on the insulating resin but on the copper foil, so that the catalyst can be easily removed. Further, since the electroless copper plating layer is formed on the copper foil, There is no need to roughen the resin.
[0009]
In addition, the present invention is characterized in that the etching rate of the electrolytic copper plating when the copper other than the pattern portion is removed by etching is 80% or less of the etching rate of the copper foil. Furthermore, in order to control such an etching rate, use a copper foil produced at a current density larger than the current density at the time of electrolytic copper plating as a copper foil having a thickness of 5 μm or less to be attached to an interlayer insulating resin or prepreg, It is also a feature of the present invention that an etching solution mainly containing an acid excluding halogen and hydrogen peroxide is used for etching removal.
[0010]
Generally, the crystal structure of electrolytic copper produced at a high current density is different from that produced at a low current density. In addition, since the main components of the etching liquid as described above are weakly diffusion-controlled and reaction-controlled, the etching rate varies depending on the crystal structure of copper. That is, the copper foil of the present invention manufactured with a high density current is easily etched, and the copper electroplating of the present invention applied with a lower density current is difficult to etch, so that copper other than the pattern portion is quickly removed. Thus, a significant decrease in the top width of the conductor circuit is suppressed, and a printed wiring board with good circuit formability can be manufactured. In particular, when sulfuric acid is used as an acid excluding halogen, which is the main component of the etching solution, very good fine wiring formability is brought about. In addition, since the difference in etching rate due to the difference in crystal structure is conspicuous during low-temperature etching, the etching solution temperature should be as low as possible to suppress excessive dissolution of the conductor circuit, resulting in better fine wiring. Will form.
[0011]
The present invention is also characterized by including a step of forming an electroless Ni / Au plating layer on the outermost surface of the conductor circuit.
[0012]
With the features of the present invention as described above, it is possible to provide a printed wiring board having high reliability and good circuit formation.
[0013]
The term “current density” used in the present invention represents the magnitude of current per unit area of the electrode, and is used in the ordinary sense understood by those skilled in the art.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method of the printed wiring board by this invention is demonstrated still in detail using FIG.
[0015]
First, an insulating base material is processed to produce an inner layer circuit board. The formation of the conductor circuit on the surface of the insulating base material is generally a subtractive method performed by etching a copper-clad laminate, but is not particularly limited. Further, through holes such as through holes are formed in the insulating base material to form an inner layer conductor circuit, thereby obtaining an inner layer circuit board. Although FIG. 1 (a) shows a single-layer double-sided board, the inner-layer circuit board may be a multilayer board.
[0016]
Next, it is necessary to roughen the inner layer copper pattern on the surface of the inner layer circuit board and improve the adhesion to the interlayer resin insulating layer formed on the copper pattern. Specifically, there are a method of forming acicular electroless plating on the inner layer copper pattern, a method of oxidizing (blackening) -reducing the inner layer copper pattern, a method of etching the inner layer copper pattern, and the like.
[0017]
Next, an interlayer insulating resin with copper foil is laminated on the inner layer circuit board obtained as described above, as shown in FIG. As the interlayer insulating resin, those containing an epoxy resin or a polyimide resin as a main component are preferable, but acrylic resin, polyimide resin, benzocyclobutene resin, fluorine resin, cyanate resin, PPE, etc. Good. Instead of laminating the interlayer insulating resin with copper foil, the copper foil may be laminated via a prepreg. The thickness of the interlayer resin insulation layer is about 10 to 100 μm, desirably 20 to 60 μm, and the thickness of the copper foil is preferably 5 μm or less. Further, the copper foil used here may be any copper foil produced at a current density higher than the current density at the time of electrolytic copper plating, but preferably one produced at a current density of 5 A / dm 2 or more is used. If the current density at the time of producing the copper foil is low, there is a problem that the etching rate is slow in the subsequent etching process, which hinders circuit formation.
[0018]
Then, as shown in FIG. 1C, IVH is formed on the interlayer resin insulation layer from above the copper foil. As a method of forming IVH, it is preferable to use a laser. Lasers that can be used here include gas lasers such as CO 2 , CO, and excimer, and solid lasers such as YAG. Since a CO 2 laser can easily obtain a large output, it is suitable for processing IVH of φ50 μm or more. When processing a fine IVH of φ50 μm or less, a YAG laser with a shorter wavelength and good condensing property is suitable.
[0019]
Next, the resin residue inside IVH is removed using an oxidizing agent such as permanganate, chromate, or chromic acid.
[0020]
Next, catalyst nuclei are applied on the copper foil and inside the IVH. A precious metal ion or a palladium colloid is used for imparting the catalyst nucleus. In particular, it is preferable to use palladium colloid because it is inexpensive.
[0021]
Next, as shown in FIG. 1D, a thin electroless plating layer is formed on the copper foil provided with the catalyst nucleus and inside the IVH. For this electroless plating, commercially available products mainly composed of copper sulfate, formalin, complexing agent, sodium hydroxide and the like can be used. For example, CUST2000 (trade name, manufactured by Hitachi Chemical Co., Ltd.) or CUST201 (Hitachi). The product name, manufactured by Kasei Kogyo Co., Ltd., and the like are listed, but not limited thereto. The thickness of plating should just be the thickness which can perform the following electrolytic copper plating, Preferably it is 0.1-1 micrometer.
[0022]
Next, as shown in FIG. 1 (e), an electroplating resist is formed on the IVH on the electroless plating layer and at places other than the conductor circuit. The thickness of the electroplating resist is preferably the same as or thicker than the conductor to be subsequently plated. Resins that can be used for electroplating resist include liquid resists such as PMER P-LA900PM (trade name, manufactured by Tokyo Ohka Co., Ltd.), HW-425 (trade name, Hitachi Chemical Co., Ltd.), RY-3025 (Hitachi) There are dry films such as Kasei Kogyo Co., Ltd. (trade name).
[0023]
Next, an electrolytic copper plating layer is formed as shown in FIG. For copper electroplating, copper sulfate electroplating or pyrophosphoric acid electroplating, which are usually used for printed wiring boards, can be used. The thickness of electrolytic copper plating should just be used as a conductor circuit, and it is preferable that it is the range of 1-100 micrometers, and it is more preferable that it is the range of 5-50 micrometers. Further, the current density at the time of forming the copper electroplating layer may be smaller than the current density at the time of producing a copper foil having a thickness of 5 μm or less, but is preferably 0.5 A / dm 2 or more and 5 A / dm 2 or less. If the current density at the time of forming the copper electroplating layer is higher than the current density at the time of copper foil preparation, it will be easily dissolved excessively in the subsequent etching step, which hinders the formation of a good circuit.
[0024]
Next, the electroplating resist is stripped using an alkaline stripping solution, sulfuric acid, or a commercially available resist stripping solution.
[0025]
Next, the formation of the circuit is completed by removing the copper other than the pattern portion by using an etching solution mainly composed of an acid other than halogen and hydrogen peroxide. (FIG. 1 (g)) The etching solution of the present invention is a solution comprising a solvent and an additive in addition to the above main components. As the solvent, water is preferably used from the viewpoint of cost, handleability, and safety. Alcohol etc. may be added to. In addition, a hydrogen peroxide stabilizer or the like can be added as an additive. Furthermore, sulfuric acid, nitric acid, etc. are mentioned as acids other than the halogen which are the main components of this invention, Preferably, a sulfuric acid is used.
[0026]
In order to obtain the top width and the bottom width of the conductor circuit as designed by etching away the copper other than the pattern portion using the etching solution of the present invention, the etching rate of the copper electroplating is the same as the etching rate of the copper foil. It is preferable that it is 80% or less.
[0027]
When sulfuric acid is used as the acid other than halogen, it is preferable to use 10 to 300 g / L sulfuric acid and 10 to 200 g / L hydrogen peroxide as the concentration of the main component of the etching solution. When the concentration is lower than the above-mentioned concentration range, the workability is poor because the etching rate is low, and when the concentration is higher than the above-mentioned concentration region, the etching rate is high, and it is difficult to control the etching amount. Moreover, it is preferable from the surface of workability | operativity to control so that it may become 1-15 micrometers / min as an etching rate of copper foil. Moreover, since the difference in etching rate due to the difference in crystal structure depends on the temperature of the etching solution, the temperature of the etching solution at the time of etching removal is preferably 20 to 50 ° C., more preferably 20 to 40 ° C. preferable. Further, as the etching time, a time during which a desired conductor circuit width can be formed may be determined by experiments, but it is preferably in the range of 10 seconds to 10 minutes for workability, etching uniformity, and the like. .
[0028]
Furthermore, a gold plating process can also be performed on the conductor circuit pattern formed as described above. As a method for forming the gold plating layer, after activation of the conductor circuit interface with an activation treatment solution such as SA-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.), NIPS-100 (Hitachi Chemical Industry) A nickel layer of about 1 to 10 μm is formed by an electroless nickel plating solution such as a product name manufactured by Co., Ltd., and HGS-100 (product name manufactured by Hitachi Chemical Co., Ltd.) is formed on the upper surface of the nickel layer. A gold plating base layer of about 0.01 to 0.1 μm is formed with a displacement gold plating solution, and further, an electroless gold plating solution such as HGS-2000 (manufactured by Hitachi Chemical Co., Ltd., trade name) is formed on the upper surface thereof. Although a method of forming a gold plating finish layer of about 1 to 1 μm is mentioned, of course, the method is not limited to this, and any method suitable for a gold plating process that can be normally performed may be used.
[0029]
【Example】
Example 1
As shown to Fig.1 (a), MCL-E-679 which is a glass cloth base material epoxy copper clad laminated board of thickness 0.2mm which bonded together the copper foil of thickness 18 micrometers on both surfaces to the insulating base material ( The copper foil of the unnecessary part was removed by etching using Hitachi Chemical Co., Ltd. (trade name) to form the through-hole 12 to form the inner-layer conductor circuit 10 and the inner-layer circuit board 11 was produced.
[0030]
Using the MEC etch BOND CZ-8100 (trade name, manufactured by MEC Co., Ltd.), the inner layer conductor circuit 10 of the inner layer circuit board 11 is spray sprayed under the conditions of a liquid temperature of 35 ° C. and a spray pressure of 0.15 MP. The copper surface is roughened to create irregularities with a roughness of about 3 μm, and immersed using MEC etch BOND CL-8300 (trade name, manufactured by MEC Co., Ltd.) at a liquid temperature of 25 ° C. and an immersion time of 20 seconds. The copper surface was subjected to rust prevention treatment.
[0031]
As shown in FIG. 1B, MCF-7000LX (manufactured by Hitachi Chemical Co., Ltd., product manufactured by applying an adhesive to a 3 μm copper foil 13 produced at a current density of 10 A / dm 2 on both surfaces of the inner layer circuit board 11. Name) was heated and pressurized laminated at 170 ° C. and 30 kgf / cm 2 for 60 minutes to form an interlayer insulating resin layer 14 having a thickness of 40 μm.
[0032]
As shown in FIG.1 (c), IVH15 which is a non-through-hole with a diameter of 80 micrometers is opened from the copper foil 13 by the carbon dioxide impact laser drilling machine L-500 (product name made by Sumitomo Heavy Industries, Ltd.) Smear was removed by immersing in a mixed aqueous solution of potassium permanganate 65 g / L and sodium hydroxide 40 g / L at a liquid temperature of 70 ° C. for 20 minutes.
[0033]
Then, after immersing in HS-202B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium solution, at 25 ° C. for 15 minutes to give a catalyst, CUST-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is used. Then, electroless copper plating was performed at a liquid temperature of 25 ° C. for 30 minutes to form an electroless copper plating layer 16 having a thickness of 0.3 μm as shown in FIG.
[0034]
As shown in FIG.1 (e), the place which laminates the dry film photoresist RY-3025 (made by Hitachi Chemical Co., Ltd., brand name) on the surface of the electroless-plating layer 16, and performs electrolytic copper plating. The electroplating resist 17 was formed by exposing and developing ultraviolet rays through the masked photomask.
[0035]
As shown in FIG. 1 (f), using a copper sulfate bath, electrolytic copper plating is performed at a liquid temperature of 25 ° C. and a current density of 1.0 A / dm 2 for about 20 μm, and the circuit conductor width / circuit conductor interval ( The copper electroplating layer 18 was formed so that L / S) = 35/25 μm.
[0036]
Next, as shown in FIG. 1 (g), after removing the electroplating resist 17 with HTO (trade name, manufactured by Nichigo Morton Co., Ltd.) which is a resist stripping solution, 20 g / L of sulfuric acid as a main component, peroxide Copper other than the pattern portion was removed by etching using an etchant having a composition of hydrogen 10 g / L. At the time of etching, the substrate was cut into small pieces of 1 dm 2 on one side, placed in a 1 L beaker, and etched at 40 ° C. for 5 minutes using a magnetic stirrer.
[0037]
Finally, a Ni / Au plating layer 19 was formed on the conductor circuit under the conditions shown in Table 1 (FIG. 1 (h)).
[0038]
[Table 1]
Figure 0003928392
[0039]
Example 2
A substrate was produced in the same manner as in Example 1 except that electrolytic copper plating was performed at a current density of 3 A / dm 2 .
[0040]
Example 3
A substrate was prepared in the same manner as in Example 1 except that the main components of the etching solution were sulfuric acid 20 g / L, hydrogen peroxide 40 g / L, and the etching time was 60 seconds.
[0041]
Example 4
A substrate was prepared in the same manner as in Example 3 except that electrolytic copper plating was performed at a current density of 3 A / dm 2 .
[0042]
Example 5
A substrate was produced in the same manner as in Example 1 except that the main components of the etching solution were sulfuric acid 20 g / L, hydrogen peroxide 40 g / L, the etching temperature was 30 ° C., and the etching time was 100 seconds.
[0043]
Example 6
A substrate was prepared in the same manner as in Example 5 except that the electrolytic copper plating was performed at a current density of 3 A / dm 2 .
[0044]
Example 7
A substrate was prepared in the same manner as in Example 1 except that the composition of the main components of the etching solution was 20 g / L nitric acid and 10 g / L hydrogen peroxide.
[0045]
Example 8
A substrate was prepared in the same manner as in Example 1 except that the main component composition of the etching solution was 200 g / L sulfuric acid and 200 g / L hydrogen peroxide.
[0046]
Comparative Example 1
A substrate was prepared in the same manner as in Example 1 except that the main components of the etching solution were sulfuric acid 20 g / L, hydrogen peroxide 20 g / L, the etching temperature was 60 ° C., and the etching time was 100 seconds.
[0047]
Comparative Example 2
A substrate was prepared in the same manner as in Example 1 except that 30 g / L of FeCl 3 aqueous solution was used for etching copper other than the pattern portion.
[0048]
Comparative Example 3
A substrate was prepared in the same manner as in Example 1 except that 40 g / L of CuCl 2 aqueous solution and 30 g / L of hydrochloric acid were used for etching copper other than the pattern portion.
[0049]
Comparative Example 4
Example 1 except that etching of copper other than the pattern portion was performed at 30 ° C. for 30 seconds using A process liquid (trade name, manufactured by Meltex Co., Ltd.) containing tetraamminecopper chloride (II) as a main component. Similarly, a substrate was prepared.
[0050]
Comparative Example 5
As shown in FIG. 2 (a), MCL-E-679, which is a 0.2 mm thick glass cloth base epoxy copper-clad laminate in which an 18 μm thick copper foil is bonded to both sides of an insulating base material. The copper foil of the unnecessary location was removed by etching using Hitachi Chemical Co., Ltd. (trade name), the through hole 22 was formed, the inner conductor circuit 20 was formed, and the inner circuit board 21 was produced.
[0051]
The inner layer conductor circuit 20 of the inner layer circuit board 21 is subjected to spray spraying using MEC etch BONDCZ-8100 (trade name, manufactured by MEC Co., Ltd.) under the conditions of a liquid temperature of 35 ° C. and a spray pressure of 0.15 MP. The copper surface is roughened to create irregularities with a roughness of about 3 μm, and immersed using MEC etch BOND CL-8300 (trade name, manufactured by MEC Co., Ltd.) at a liquid temperature of 25 ° C. and an immersion time of 20 seconds. The copper surface was subjected to rust prevention treatment.
[0052]
As shown in FIG. 2 (b), BL-9700 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is an insulating adhesive, is applied on both surfaces of the inner layer circuit board 21 to a thickness of 40 μm, and is heated at 170 ° C. for 60 minutes. The interlayer insulating resin layer 24 was formed by heating.
[0053]
As shown in FIG. 2 (c), a carbon dioxide gas impact laser drilling machine L-500 (trade name, manufactured by Sumitomo Heavy Industries, Ltd.) was used to open IVH25, which is a non-through hole with a diameter of 80 μm, and 65 g of potassium permanganate. / L and 40 g / L of sodium hydroxide in a mixed aqueous solution at a liquid temperature of 70 ° C. for 20 minutes to remove smears and at the same time create fine irregularities on the surface.
[0054]
Next, using an ultrasonic cleaning apparatus PUC-0586 (trade name, manufactured by Tokyo Ultrasonic Giken Co., Ltd.), ultrasonic treatment is performed for 5 minutes under conditions of cleaning liquid ion-exchanged water, a transmission frequency of 25 kHz, and an output of 600 W. The fragile layer was removed.
[0055]
Then, after immersing in HS-202B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium solution, at 25 ° C. for 15 minutes to give a catalyst, CUST-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used, and electroless copper plating was performed at a liquid temperature of 25 ° C. for 30 minutes to form an electroless copper plating layer 26 having a thickness of 0.3 μm as shown in FIG.
[0056]
As shown in FIG. 2E, a dry film photoresist, RY-3025 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is laminated on the surface of the electroless copper plating layer 26 and subjected to electrolytic copper plating. The electroplating resist 27 was formed by exposing and developing ultraviolet rays through a photomask having a mask of.
[0057]
As shown in FIG. 2 (f), using a copper sulfate bath, electrolytic copper plating is performed for about 20 μm under the conditions of a liquid temperature of 25 ° C. and a current density of 1.0 A / dm 2 , and the circuit conductor layer / circuit conductor interval ( The copper electroplating layer 28 was formed so that L / S) = 30/30 μm.
[0058]
Next, as shown in FIG. 2G, after removing the electroplating resist 27 with HTO (trade name, manufactured by Nichigo Morton Co., Ltd.) which is a resist stripping solution, 20 g / L of sulfuric acid as a main component, Copper other than the pattern portion was removed by etching using an etching solution having a composition of hydrogen peroxide of 10 g / L. At the time of etching, the substrate was cut into small pieces of 1 dm 2 on one side, placed in a 1 L beaker, heated to 40 ° C., and then etched for 1 minute with a magnetic stirrer.
[0059]
Finally, as shown in FIG. 2 (h), a Ni / Au plating layer 29 was formed by the same method as in Example 1 to produce a substrate.
[0060]
Comparative Example 6
A substrate was prepared in the same manner as in Comparative Example 5 except that 30 g / L of FeCl 3 aqueous solution was used for etching copper other than the pattern portion.
[0061]
Comparative Example 7
A substrate was prepared in the same manner as in Comparative Example 5 except that 40 g / L of CuCl 2 aqueous solution and 30 g / L of hydrochloric acid were used for etching copper other than the pattern portion.
[0062]
Comparative Example 8
Comparative Example 5 except that etching of copper other than the pattern portion was performed at 30 ° C. for 30 seconds using an A process liquid (trade name, manufactured by Meltex Co., Ltd.) containing tetraamminecopper chloride (II) as a main component. Similarly, a substrate was prepared.
[0063]
Comparative Example 9
A substrate was prepared in the same manner as in Example 1 except that the main components of the etching solution were hydrochloric acid 40 g / L and hydrogen peroxide 10 g / L.
[0064]
Comparative Example 10
A substrate was prepared in the same manner as in Example 1 except that the main components of the etching solution were 3 g / L sulfuric acid and 3 g / L hydrogen peroxide.
[0065]
Comparative Example 11
A substrate was prepared in the same manner as in Example 1 except that the current density at the time of copper foil preparation was 5 A / dm 2 and the current density at the time of electrolytic copper plating was 7 A / dm 2 .
[0066]
Table 2 shows the results of evaluating the conductor top width, conductor bottom width, inter-circuit etching residue, and inter-circuit Au plating deposition of the substrates prepared in Examples 1 to 8 and Comparative Examples 1 to 11. In many cases, the inter-circuit etching residue and inter-circuit Au plating deposition occur in a shape that forms a skirt from the circuit as shown in FIG. Therefore, the length obtained by dividing the difference between the top and the bottom between the circuits by 2 is the length, and if this value is 5 μm or more, there is an inter-circuit etching residue (the measurement method for inter-circuit Au plating deposition is also the same). The top width and the bottom width between the conductor and the circuit are obtained by taking an image of the substrate from above with an optical microscope, measuring 20 points arbitrarily based on image-processed data, and calculating an average.
[0067]
[Table 2]
Figure 0003928392
[0068]
The substrates produced in Examples 1 to 8 were finished with the conductor top width almost as designed, and there was almost no difference between the top width and the bottom width, and the circuit formability was good. On the other hand, in Comparative Example 1, since the temperature of the etching solution was set high, there was almost no difference between the etching rates of the copper foil and the conductor circuit, and the problem that the conductor circuit was excessively dissolved occurred. In Comparative Examples 2 to 4 and 6 to 9, since the diffusion rate-limiting etching solution is used, the portion of the conductor top that is good per solution is excessively dissolved, etching between circuits is likely to remain, and Au plating deposition between circuits is likely to occur. I understood that. In Comparative Example 5, it was found that Pd removal tends to be insufficient and Au plating deposition between circuits tends to occur. In Comparative Example 10, since the main component concentration of the etching solution is thin, the etching time until the circuit is formed as designed is too long, and the workability is poor. In Comparative Example 11, since the current density at the time of electrolytic copper plating is larger than the value of the current density at the time of copper foil preparation, there is almost no difference in the etching rate between copper other than the pattern portion and the conductor top portion, and the conductor circuit is excessive. It has been etched.
[0069]
Although the present invention has been described above with reference to a plurality of embodiments, it should not be understood that this description limits the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques not described herein will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the appropriate claims from the above description.
[0070]
【The invention's effect】
As described above, according to the present invention, it is possible to produce a printed wiring board with few circuit defects between conductor circuits and good circuit formation.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a manufacturing process of a printed wiring board according to the present invention.
2 is a cross-sectional view showing a process for manufacturing a printed wiring board of Comparative Example 5. FIG.
FIG. 3 is a cross-sectional view of a circuit showing inter-circuit etching residue or inter-circuit Au plating deposition.
[Explanation of symbols]
10, 20 Inner layer conductor circuits 11, 21 Inner layer circuit boards 12, 22 Through hole 13 Copper foil 14, 24 Interlayer insulating resin layers 15, 25 IVH
16, 26 Electroless copper plating layer 17, 27 Electroplating resist 18, 28 Electrocopper plating layer 19, 29 Ni / Au plating layer

Claims (11)

導体回路を有する内層回路基板の上下面に厚み5μm以下の銅箔を貼り付けた層間絶縁樹脂を積層する工程と、前記内層回路基板に層間接続のためのIVH(インタースティシャルバイアホール)を形成する工程と、給電層として薄付け無電解銅めっきを行い、電気めっきレジストを形成した後に、前記銅箔作製時の電流密度よりも小さい電流密度で電気銅めっきを行う工程と、前記電気めっきレジストを除去し、パターン部以外の銅を、ハロゲンを含まない酸と過酸化水素を主成分とするエッチング液でエッチング除去することで導体回路パターンを形成する工程と、を少なくとも有することを特徴とするプリント配線板の製造方法。A process of laminating an interlayer insulating resin having a copper foil of 5 μm or less on the upper and lower surfaces of an inner layer circuit board having a conductor circuit, and forming an IVH (interstitial via hole) for interlayer connection on the inner layer circuit board Performing a thin electroless copper plating as a power feeding layer, forming an electroplating resist, and then performing an electrocopper plating at a current density smaller than the current density at the time of producing the copper foil, and the electroplating resist And a step of forming a conductor circuit pattern by etching away copper other than the pattern portion with an etching solution mainly containing a halogen-free acid and hydrogen peroxide. Manufacturing method of printed wiring board. 導体回路を有する内層回路基板の上下面にプリプレグを介して厚み5μm以下の銅箔を積層する工程と、前記内層回路基板に層間接続のためのIVH(インタースティシャルバイアホール)を形成する工程と、給電層として薄付け無電解銅めっきを行い、電気めっきレジストを形成した後に、前記銅箔作製時の電流密度よりも小さい電流密度で電気銅めっきを行う工程と、前記電気めっきレジストを除去し、パターン部以外の銅を、ハロゲンを含まない酸と過酸化水素を主成分とするエッチング液でエッチング除去することで導体回路パターンを形成する工程と、を少なくとも有することを特徴とするプリント配線板の製造方法。A step of laminating copper foils having a thickness of 5 μm or less on the upper and lower surfaces of the inner layer circuit board having a conductor circuit, and a step of forming IVH (interstitial via hole) for interlayer connection on the inner layer circuit board; Then, after performing thin electroless copper plating as a power feeding layer and forming an electroplating resist, a step of performing electrocopper plating at a current density smaller than the current density at the time of producing the copper foil, and removing the electroplating resist And a step of forming a conductor circuit pattern by etching away copper other than the pattern portion with an etching solution mainly containing a halogen-free acid and hydrogen peroxide as a main component. Manufacturing method. 前記無電解銅めっきの厚みが0.1〜1.0μmであることを特徴とする請求項1または2に記載のプリント配線板の製造方法。  The thickness of the said electroless copper plating is 0.1-1.0 micrometer, The manufacturing method of the printed wiring board of Claim 1 or 2 characterized by the above-mentioned. 前記パターン部以外の銅をエッチング除去する際の前記電気銅めっきのエッチング速度が前記銅箔のエッチング速度の80%以下であることを特徴とする請求項1〜3に記載のプリント配線板の製造方法。  The printed wiring board according to claim 1, wherein an etching rate of the electrolytic copper plating when etching away copper other than the pattern portion is 80% or less of an etching rate of the copper foil. Method. 前記銅箔が5A/dm以上の電流密度により作製された電解銅箔であることを特徴とする請求項1〜に記載のプリント配線板の製造方法。Method for manufacturing a printed wiring board according to claim 1-4, characterized in that said copper foil is an electrolytic copper foil manufactured by the 5A / dm 2 or more current density. 前記電気銅めっきは0.5A/dm以上5A/dm以下の電流密度で行われることを特徴とする請求項1〜に記載のプリント配線板の製造方法。The copper electroplating method for producing a printed wiring board according to claim 1-5, characterized in that it is carried out at a current density of 0.5A / dm 2 or more 5A / dm 2 or less. 前記エッチング液の主成分が硫酸と過酸化水素であることを特徴とする請求項1〜6に記載のプリント配線板の製造方法。The method for producing a printed wiring board according to claim 1 , wherein the main components of the etching solution are sulfuric acid and hydrogen peroxide. 前記エッチング液の主成分が5〜300g/Lの濃度の硫酸と5〜200g/Lの濃度の過酸化水素であることを特徴とする請求項1〜6に記載のプリント配線板の製造方法。The method for producing a printed wiring board according to claim 1 , wherein the main components of the etching solution are sulfuric acid having a concentration of 5 to 300 g / L and hydrogen peroxide having a concentration of 5 to 200 g / L. 前記パターン部以外の銅をエッチング除去する際の前記エッチング液の温度が20℃〜50℃の範囲であることを特徴とする請求項1〜に記載のプリント配線板の製造方法。Method for manufacturing a printed wiring board according to claim 1-8, wherein the temperature of the etching liquid when etching away the copper other than the pattern portion ranges from 20 ° C. to 50 ° C.. 前記銅箔のエッチング速度が1〜15μm/分であることを特徴とする請求項1〜に記載のプリント配線板の製造方法。Method for manufacturing a printed wiring board according to claim 1-9, wherein the etching rate of the copper foil is 1 to 15 m / min. 前記導体回路パターンの最表面に無電解Ni/Auめっき層を形成する工程を含むことを特徴とする請求項1〜10に記載のプリント配線板の製造方法。Method for manufacturing a printed wiring board according to claim 1-10, characterized in that it comprises a step of forming an electroless Ni / Au plated layer on the outermost surface of the conductor circuit pattern.
JP2001278325A 2001-09-13 2001-09-13 Method for manufacturing printed wiring board Expired - Fee Related JP3928392B2 (en)

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