JP2004031812A

JP2004031812A - Method of manufacturing wiring board

Info

Publication number: JP2004031812A
Application number: JP2002188442A
Authority: JP
Inventors: Shinji Yuri; 由利　伸治; Tomoe Suzuki; 鈴木　友恵; Kazuhisa Sato; 佐藤　和久; Kozo Yamazaki; 山崎　耕三
Original assignee: NGK Spark Plug Co Ltd
Current assignee: Niterra Co Ltd
Priority date: 2002-06-27
Filing date: 2002-06-27
Publication date: 2004-01-29
Anticipated expiration: 2022-06-27
Also published as: JP4001786B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board manufacturing method which comprises a core board manufacturing process of filling through-holes bored in a core material with resin so as to manufacture a core board that is equipped with resin layers formed on its front and rear surface and nearly uniform in thickness. <P>SOLUTION: The wiring board manufacturing method comprises the core board 1a manufacturing processes that include a plugging process of forming the resin layers 8 and 9 on the front surface 3 and rear surface 4 of a metal plate (core material) 2 having through-holes 5 bored in it as penetrating through its surfaces 3 and 4, and filling the through-holes 5 with resin 10 at the same time. The metal plate 2 is structured as follows: From the viewpoint of the front surface 3, in the regions 2a and 2c of the metal plate 2 where the through-holes 5 filled with the resin 10 which a through-hole conductor 14 penetrates through inside later are sparse, a dummy through-hole 5a filled with the resin 10 which the through-hole conductor 14 never penetrates through inside later is provided. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、コア材を芯材とするコア基板の製造工程を含む配線基板の製造方法方法に関する。
【０００２】
【従来の技術】
配線基板のベースとなるコア基板の芯材であるコア材に金属板が用いられる場合がある。この金属板の表面と裏面との間を貫通する貫通孔内には、追ってその中心部を同軸心状に貫通するスルーホール導体の周りを絶縁するため、樹脂が充填される。上記金属板の貫通孔に樹脂を充填する方法には、以下のものがある。
（１）ペースト状の樹脂を印刷法やディスペンス法で貫通孔に充填する方法。
（２）ドライタイプの樹脂フィルムを金属板の表面および裏面にラミネートし、それら厚み方向に沿ってプレスすることで、上記樹脂を貫通孔に圧入する方法。
（３）プリプレグのような半硬化状態の樹脂を、ホットプレスによって貫通孔に流入する方法。
【０００３】
上記（１），（２）の方法では、金属板（コア材）の貫通孔に前記樹脂を充填した直後では、かかる金属板の表面および裏面が平坦であっても、その後に充填した樹脂を硬化するためのキュア処理を行うと、かかる樹脂の硬化収縮に伴って、貫通孔内の樹脂の真上および真下の位置には、それぞれ凹みが発生する。
例えば、図８（Ａ）に示すように、表面４２および裏面４３を有し、且つこれらの間を貫通する複数の貫通孔４４を有する厚みが０．２５ｍｍの金属板（コア材）４０は、図示で左側の領域４０ａにおいて貫通孔４４が密な分布で、図示で右側の領域４０ｂにおいて貫通孔４４が疎な分布となっている。各貫通孔４４の内径は、約０．３ｍｍである。
先ず、図８（Ｂ）に示すように、金属板４０の表面４２および裏面４３に、厚さ６０μｍのドライタイプの樹脂フィルム４５，４６をラミネートする。
【０００４】
次いで、図８（Ｂ）中の矢印で示すように、上記樹脂フィルム４５，４６を金属板４０に押し付けるように厚み方向に沿ってプレス（真空熱プレスなどによる）する。その結果、図８（Ｃ）に示すように、上記樹脂フィルム４５，４６は、圧縮された樹脂層４７，４８になると共に、その一部の樹脂４９が複数の貫通孔４４内に圧入し、当該貫通孔４４の内部に充満する。
そして、上記樹脂層４７，４８および樹脂４９が形成された金属板４０を加熱し、樹脂層４７，４８などを硬化させるキュア処理を施す。
その結果、図８（Ｄ）に示すように、上記樹脂４９の硬化収縮に伴って、貫通孔４４の真上および真下の樹脂層４７，４８の表面には、凹み５０が生じる。
【０００５】
上記凹み５０に伴う金属板４０の表面４２および裏面４３に形成される樹脂層４７，４８の厚みは、図８（Ｅ）に示すように、貫通孔４の分布が密な領域４０ａでは、貫通孔４４に多量の樹脂４９が充填されるため、薄くなる。一方、貫通孔４４の密度が疎な領域４０ｂでは、貫通孔４４に樹脂４９が少量しか充填されないため、厚くなり易い。これに起因して、図８（Ｅ）に示すように、コア基板ｋの表面５２および裏面５３間における厚みにバラツキが生じると、かかる表面５２および裏面５３に形成する表面配線層および裏面配線層は、歪むと共に、これらの上方に形成される絶縁層やビルドアップ配線層も平坦性が損なわれる。このため、得られる配線基板の信頼性を損ねる、という問題があった。
【０００６】
【発明が解決すべき課題】
本発明は、以上に説明した従来の技術における問題点を解決し、表面と裏面との間に複数の貫通孔が形成されたコア材の各貫通孔内に樹脂を充填し且つ上記表面と裏面とに樹脂層を形成するコア基板を、ほぼ均一な厚みにより製造できるコア基板の製造工程を含む配線基板の製造方法を提供する、ことを課題とする。
【０００７】
【課題を解決するための手段】
本発明は、上記課題を解決するため、発明者らによる鋭意研究および調査の結果、コア材における複数の貫通孔に充填される樹脂の量を当該コア材の全領域で平均化する、ことに着想して成されたものである。
即ち、本発明による第１の配線基板の製造方法（請求項１）は、表面および裏面を有し且つかかる表面と裏面との間を貫通する複数の貫通孔を有するコア材に対し、上記コア材の表面および裏面にそれぞれ樹脂層を形成し、同時に上記貫通孔内に樹脂を充填し穴埋めするコア基板の製造工程を含み、かかる工程において、上記コア材を貫通する複数の貫通孔の平面視における分布密度が、かかるコア材の表面および裏面の全面において、ほぼ平均化している、ことを特徴とする。
【０００８】
これによれば、コア材を貫通する複数の貫通孔は、かかるコア材の全面において分布密度がほぼ平均化する、即ち、コア材におけるどの領域においても配置される貫通孔がほぼ同数となるように、配置される。このため、コア材の表面および裏面に樹脂フィルムなどを配置し、これらを厚み方向に沿ってプレスなどすると、各貫通孔に樹脂が圧入されると共に、コア材の表面および裏面に形成される表面樹脂層や裏面樹脂層の厚みも、当該コア材の全面において、ほぼ均一とすることができる。従って、かかるコア材、充填樹脂、表面樹脂層、および裏面樹脂層を有するコア基板を用いることによって、コア基板の表面や裏面に形成する表面配線層および裏面配線層は基より、これらの上に形成される絶縁層やビルドアップ配線層も平坦に形成した信頼性の高い配線基板を得ることが容易となる。
尚、上記コア材には、後述する金属板のほか、樹脂板や、表面および裏面の金属箔を貼り付けた樹脂板なども含まれる。また、上記樹脂には、絶縁性の樹脂のほか、導電性樹脂も含まれる。
【０００９】
また、本発明による第２の配線基板の製造方法（請求項２）は、表面および裏面を有し且つかかる表面と裏面との間を貫通する複数の貫通孔を有するコア材に対し、上記コア材の表面および裏面に樹脂層それぞれを形成し、同時に上記貫通孔内に樹脂を充填し穴埋めするコア基板の製造工程を含み、かかるコア材の上記表面から見て、追って内側をスルーホール導体が上記樹脂を貫通して形成される貫通孔が密な領域では、追って内側をスルーホール導体が貫通しないダミー貫通孔を形成しないかまたは少し形成すると共に、追って内側をスルーホール導体が上記樹脂を貫通して形成される貫通孔が疎な領域では、追って内側をスルーホール導体が貫通しないダミー貫通孔を多く形成する、ことを特徴とする。
【００１０】
これによれば、コア材において貫通孔が密な領域には、ダミー貫通孔を形成しないか少しだけ形成するに留め、逆に貫通孔が疎な領域では、ダミー貫通孔を多く形成することにより、かかるコア材の全面においてダミー貫通孔を含む貫通孔の分布密度がほぼ平均化する。即ち、かかるコア材のどの領域においてもダミー貫通孔を含む貫通孔がほぼ同数となるように形成される。
従って、前述したように樹脂をコア材のダミー貫通孔を含む各貫通孔に圧入し、且つかかる樹脂を表面および裏面に形成すると、各貫通孔に樹脂が充填され、コア材の表面や裏面にそれぞれ形成される樹脂層の厚みも、当該コア材の全面において、ほぼ均一であるコア基板を得ることができる。かかるコア基板を用いることで、前述した信頼性の高い配線基板を容易に形成することが可能となる。
【００１１】
更に、本発明による第３の配線基板の製造方法（請求項３）は、表面および裏面を有し且つかかる表面と裏面との間を貫通する複数の貫通孔を有するコア材に対し、上記コア材の表面および裏面に樹脂層をそれぞれ形成し、同時に上記貫通孔内に樹脂を充填し穴埋めするコア基板の製造工程を含み、上記複数の貫通孔の分布密度が疎なコア材の領域における貫通孔の内部容積と、上記貫通孔の分布密度が密なコア材の領域の貫通孔の内部容積と、がほぼ等しくなるように、上記分布密度が疎なコア材の領域における貫通孔の内径と、上記分布密度が密なコア材の領域の貫通孔の内径との間に、差を設けている、ことを特徴とする。
【００１２】
これによれば、コア材において貫通孔が密な領域には、例えば小さな内径の貫通孔を形成し、一方、貫通孔が疎な領域では、大きな内径の貫通孔を形成しているため、各領域における全貫通孔の内部容積が互いにほぼ等しくなる。このため、前述したように樹脂をコア材の各貫通孔に圧入し、且つかかる樹脂を表面および裏面に形成すると、各貫通孔に樹脂が充填され、コア材の表面や裏面に形成される表面樹脂層や裏面樹脂層の厚みも、当該コア材の全面において、ほぼ均一であるコア基板を得ることができる。従って、かかるコア基板を用いることにより、前述した信頼性の高い配線基板を容易に形成することが可能となる。
【００１３】
また、本発明には、前記工程は、前記コア材の表面および裏面にそれぞれ樹脂フィルムを個別に積層し、かかる一対の樹脂フィルムを上記コア材の厚み方向に沿って押圧することにより行われる、配線基板の製造方法（請求項４）も含まれる。これによれば、コア材における各貫通孔に圧入される樹脂の量、表面や裏面に形成される各樹脂層の厚みを、前述した第１乃至第３の何れかの方法に沿って、容易に制御することができる。従って、全面においてほぼ均一な厚みを有するコア基板を一層確実に得ることが可能となる。
【００１４】
更に、本発明には、前記コア材は、前記表面、裏面、および貫通孔を有する金属板である、配線基板の製造方法（請求項５）も含まれる。
これによれば、所要の強度を有し、貫通孔内が樹脂で充填され、且つ表面および裏面に平坦な樹脂層が形成された金属板をコア材とするコア基板を確実に製造できる。かかるコア基板の表面と裏面とに形成される平坦な表面配線層および裏面配線層や、これらの少なくとも一方の上方に形成される平坦な絶縁層やビルドアップ配線層を含む強固な配線基板を製造することが可能となる。
尚、上記金属板には、Ｃｕ−２．３ｗｔ％Ｆｅ−０．０３ｗｔ％Ｐ（１９４アロイ）などの銅合金、純銅、無酸素銅、Ｆｅ−４２ｗｔ％Ｎｉ（４２アロイ）やＦｅ−３６ｗｔ％Ｎｉ（インバー）などのＦｅ−Ｎｉ系合金、その他の鋼種、チタンやその合金、およびアルミニウムやその合金などからなる板が含まれる。
【００１５】
付言すれば、本発明には、前記工程の後に、得られたコア基板の表面および裏面に表面配線層と裏面配線層とを個別に形成する工程と、上記コア基板の表面および裏面の少なくとも一方の上方に、複数の絶縁層およびこれらの間に位置する複数の配線層とを含むビルドアップ層を形成する工程を、更に含む、配線基板の製造方法も含まれ得る。これによる場合、前述した信頼性の高い破線基板を確実に製造することが可能となる。
【００１６】
【発明の実施の形態】
以下において、本発明の実施に好適な形態を図面と共に説明する。
図１（Ａ），（Ｂ）は、本発明による第１の配線基板の製造方法に用いるコア材である金属板２の平面図および断面図である。金属板２は、例えば厚みが０．２５ｍｍの前記銅合金（１９４アロイ）からなり、図１（Ａ），（Ｂ）に示すように、表面３および裏面４を有し、かかる表面３と裏面４との間には内径が約０．３ｍｍの貫通孔５が複数貫通している。複数の貫通孔５は、かかる金属板２をパンチングするか、レーザ加工、ドリル加工、またはエッチング加工によって形成される。
【００１７】
図１（Ａ）中の破線で示すように、金属板２は、平面視で４つの領域２ａ〜２ｄに区分され、このうち左上の領域２ａと左下の領域２ｃとでは、９個の貫通孔５が格子模様の各交点に位置するように配置されている。
一方、金属板２において、右上の領域２ｂと右下の領域２ｄとでは、９個の貫通孔５がやや偏平な市松模様を形成する位置にそれぞれ配置されている。
即ち、図１（Ａ），（Ｂ）に示すように、金属板２では、全領域２ａ〜２ｄにおいて、同じ内径を有する９個ずつの貫通孔５が互いにほぼ等間隔に形成されいるため、これらの領域２ａ〜２ｄにおける貫通孔５の分布密度は平均化している。
【００１８】
図２（Ａ）に示すように、金属板２の表面３および裏面４における全ての領域２ａ〜２ｄに、厚みが約２０〜８０μｍ（本実施形態では４０μｍ）でエポキシ樹脂からなるドライタイプの樹脂フィルム６，７を積層（ラミネート）する。
次に、図２（Ａ）中の矢印で示すように、上記樹脂フィルム６，７を金属板２の厚み方向に沿って、図示しないホットプレスなどよって押圧する。
その結果、図２（Ｂ）に示すように、上記樹脂フィルム６，７は、圧縮されて金属板２の表面３および裏面４に密着する樹脂層８，９となる共に、その一部は貫通孔５，５内に進入して、これらを充填する樹脂１０，１０となる。
【００１９】
次いで、樹脂層８，９および貫通孔５内の樹脂１０を有する金属板２を、図示しない加熱炉内に挿入し、大気中において約１５０℃に約６０分間加熱する硬化（キュア）処理を行う。かかる硬化処理の後における上記金属板２などの図２（Ｂ）中の一点鎖線Ｃで示す部分の拡大図を、図２（Ｃ）に示す。
前記のように、金属板２の全領域２ａ〜２ｄにおいて、９個ずつの貫通孔５が互いにほぼ等間隔に形成されているため、図２（Ｃ）に示すように、得られるコア基板１の表面１２と裏面１３との間における厚みは、殆ど均一になる。
【００２０】
以下において、コア基板１を用いた配線基板Ｋの製造工程を説明する。
図２（Ｄ）は、前記コア基板１に内蔵される金属板２の貫通孔５，５の中心部に、例えば炭酸ガスレーザを照射して、樹脂層８，９および樹脂１０の中心部に沿って、コア基板１の表面１２と裏面１３との間を貫通するスルーホールｈを形成する工程を示す。かかるスルーホールｈの内径は、約１５０μｍである。尚、上記レーザに替え、細径のドリルを用いてスルーホールｈを形成しても良い。
次に、コア基板１の表面１２、裏面１３、およびスルーホールｈ，ｈの内壁に、Ｐｄを含むメッキ触媒を被覆した後、無電解銅メッキおよび電解銅メッキを全面に施す。その結果、図３（Ａ）に示すように、各スルーホールｈの内壁に沿って円筒形のスルーホール導体１４が形成される。かかるスルーホール導体１４の中空部には、導電性または非導電性の充填樹脂１５が形成される。その後、コア基板１の表面１２と裏面１３との上に銅メッキを施す。
【００２１】
次いで、コア基板１の表面１２および裏面１３に形成された銅メッキ膜の上に、感光性樹脂からなり厚みが約２０〜３０μｍの図示しない樹脂フィルムを貼り付ける。かかるフイルムの上に、所定パターンを有するマスク（図示せず）を載置した後、当該フィルムに対して露光および現像（フォトグラフィ技術）を施して、所定のパターンを有する図示しないエッチングレジストを形成する。更に、かかるレジストを介して現像液と接触させて、上記レジストのパターン間から露出する銅メッキ膜をエッチングする。
その結果、図３（Ａ）に示すように、コア基板１の表面１２と裏面１３とには、上記パターンに倣った表面配線層１６と裏面配線層１７とが形成され、これらはスルーホール導体１４の上端または下端と接続すると共に、充填樹脂１５の両端を蓋メッキする。
【００２２】
更に、図３（Ｂ）に示すように、表面配線層１６の上に、シリカフィラなどの無機フィラを含むエポキシ樹脂フィルムからなり厚みが３０μｍの絶縁層１８を形成する。かかる絶縁層１８における所定の位置に対し、フォトリソグラフィ技術またはレーザ加工（炭酸ガスレーザなどを使用する）を施して、図示しないビアホールを複数形成する。このビアホールの底面には、表面配線層１６が露出する。
次に、絶縁層１８の表面および上記ビアホールの内壁面に前記同様のメッキ触媒を塗布した後、無電解銅メッキおよび電解銅メッキを施し、絶縁層２４の表面に銅メッキ膜を形成することにより、図３（Ｂ）に示すように、上記ビアホール内にビア（フィルドビア）導体２０を形成する。
【００２３】
次いで、銅メッキ膜が形成された絶縁層１８の上に、前記同様のエッチングレジストを形成し且つ現像を行う。その結果、図３（Ｂ）に示すように、絶縁層１８の上には、所定パターンの配線層（ビルドアップ配線）２２が形成される。この配線層２２は、ビア導体２０を介して表面配線層１６と接続される。
以上と同様にして、図３（Ｂ）に示すように、絶縁層２４、ビア導体２６、および配線層２８を形成する。かかるビア導体２６は、配線層２２，２８間を接続し、絶縁層１８，２４および配線層２２，２８はビルドアップ層ＢＵを形成する。
【００２４】
更に、図３（Ｂ）に示すように、配線層２８の上に厚みが２０μｍで最上層の絶縁層（ソルダーレジスト層）３０を形成する。かかる絶縁層３０には、図示しないＮｉ−Ａｕ層を介して、配線層２８上の適所から第１主面３２よりも高く突出するハンダバンプ３４が貫通する。
かかるハンダバンプ３４は、Ｓｎ−Ａｇ系、Ｐｂ−Ｓｎ系、Ｓｎ−Ａｇ−Ｃｕ系、Ｓｎ−Ｃｕ系、Ｓｎ−Ｚｎ系など（本実施形態ではＳｎ−Ａｇ系）の低融点合金からなり、第１主面３２上に実装される図示しないＩＣチップ（電子部品）の接続端子と個別に接続される。また、複数のハンダバンプ３４とＩＣチップの接続端子とは、アンダーフィル材により埋設され且つ保護される。
【００２５】
一方、図３（Ｂ）に示すように、コア基板１の裏面１３にも、前記同様にして所定パターンの裏面配線層１７を形成し、且つその下側に前記同様の絶縁層（ソルダーレジスト層）１９を形成する。かかる絶縁層１９において第２主面２３側に開口する開口部２５の底面には、裏面配線層１７から延びた配線２１が位置する。かかる配線２１は、その表面にＮｉメッキおよびＡｕメッキが被覆され、図示しなマザーボードなどのプリント基板との接続端子として活用される。
【００２６】
以上により、図３（Ｂ）に示すような配線基板Ｋが製造される。かかる配線基板Ｋは、前記平坦な表面１２を有するコア基板１を用いているため、この表面１２上に形成される表面配線層１６や、その上方に形成されるビルドアップ層ＢＵにおける配線層２２，２８が平坦に形成される。また、絶縁層１８，２４の厚みがバラつかず、平均化される。従って、本発明の製造方法によれば、表面１２および裏面１３が平坦なコア基板１を確実に製造できると共に、かかるコア基板１を用いた信頼性の高い配線基板Ｋを確実に製造することが可能となる。
尚、コア基板１の裏面１３の下方にも、複数の絶縁層および複数の配線層とからなるビルドアップ層を上記ビルドアップ層ＢＵと対称にして形成しても良い。
【００２７】
図４（Ａ），（Ｂ）は、本発明による第２の配線基板の製造方法に用いられる金属板（コア材）２の平面図および断面図である。金属板２は、前記同様の素材および厚みを有し、図４（Ａ），（Ｂ）に示すように、表面３と裏面４との間には、前記同様の方法により形成された内径が約０．３ｍｍの貫通孔５が複数貫通している。
図４（Ａ）中の破線で示すように、金属板２は、平面視で４つの領域２ａ〜２ｄに区分され、このうち右上の領域２ｂと左下の領域２ｃとでは、９個の貫通孔５が格子模様の各交点に位置するように配置されている。
【００２８】
一方、金属板２において、左上の領域２ａと右下の領域２ｄとでは、８個の貫通孔５が正方形を形成する位置にそれぞれ配置されている。これらの貫通孔５に囲まれた内側には、追ってスルーホール導体が貫通しないダミー貫通孔５ａが形成されている。かかるダミー貫通孔５ａの内径は、貫通孔５の内径と同じである。従って、かかるダミー貫通孔５ａと８個の貫通孔５とを含む領域２ａ，２ｄは、９個の貫通孔５を有する上記領域２ｂ，２ｃと同じ内部容積の貫通孔５，５ａが形成されている。即ち、図４（Ａ），（Ｂ）に示す金属板２は、全領域２ａ〜２ｄにおいて、同数で同じ内部容積の貫通孔５，５ａが均一に形成されている。
尚、ダミー貫通孔５ａの内径は、貫通孔５の内径と同じとする上記形態に限らず、かかる貫通孔５よりも大径または小径としても良い。
【００２９】
上記金属板２の表面３と裏面４に、前記樹脂フィルム６，７をラミネートし、且つ前記同様の方法によりプレスし且つ硬化処理することにより、図４（Ｃ）に示すように、表面１２と裏面１３との間における厚みが、殆ど均一になるコア基板１ａが得られる。コア基板１ａの図４（Ｃ）中の一点鎖線ａで示す部分に、前記同様にしてスルーホールｈを形成した部分の拡大図を、図５（Ａ）に示す。この際、図５（Ａ）に示すように、ダミー貫通孔５ａに充填された樹脂１０には、スルーホールｈは形成されない。
次に、前述した方法により、図５（Ｂ）に示すように、コア基板１ａの表面１２と裏面１３とに、所定パターンの表面配線層１６と裏面配線層１７とを個別に形成する。
【００３０】
更に、図５（Ｃ）に示すように、コア基板１ａの表面１２および表面配線層１６の上方に、絶縁層１８，２４および配線層２２，２８を含むビルドアップ層ＢＵなどを形成する。そして、コア基板１ａの裏面１３および裏面配線層１７の下方に絶縁層１９などを、前記同様の方法により形成する。この結果、図５（Ｃ）に示す配線基板Ｋ１を得ることができる。この際、表面配線層１６、裏面配線層１７、および配線層２２，２８などは、コア基板１ａの表面１２および裏面１３の全面における厚みがほぼ均一であるため、平坦に形成することができる。
尚、上記コア基板１ａの裏面１３の下方にも、上記と同様のビルドアップ層ＢＵをこれと対称にして形成しても良い。
【００３１】
図６（Ａ），（Ｂ）は、本発明による第３の配線基板の製造方法に用いられる金属板（コア材）２の平面図および断面図である。金属板２は、前記同様の素材と厚みを有し、図６（Ａ），（Ｂ）に示すように、表面３と裏面４との間には、前記同様の方法により形成された内径ｄが約０．３０ｍｍの貫通孔５が複数貫通している。
図６（Ａ）中の破線で示すように、金属板２は、平面視で４つの領域２ａ〜２ｄに区分され、このうち右上の領域２ｂと左下の領域２ｃとでは、９個ずつの貫通孔５が格子模様の各交点に位置するように配置されている。
一方、金属板２において、左上の領域２ａと右下の領域２ｄとでは、７個の貫通孔５がコ字形を形成する位置にそれぞれ配置されている。これらの貫通孔５に囲まれた内側のほぼ中央には、内径Ｄが約０．４２ｍｍの貫通孔５ｂが１個形成されている。かかる貫通孔５ｂの内径Ｄは、上記貫通孔５の内径ｄの約１．４倍であり、内径Ｄと内径ｄとの間には約０．１ｍｍの差がある。
【００３２】
即ち、貫通孔５ｂの内部容積は、貫通孔５の内部容積の約２倍となる。このため、上記領域２ｂや領域２ｃにおける９個の貫通孔５全部の内部容積と、上記領域２ａや領域２ｄにおける７個の貫通孔５および１個の貫通孔５ｂの内部容積との総和とは、ほぼ等しくなる。換言すると、かかる金属板２は、９個の貫通孔５を必要とする領域２ｂ，２ｃと８個の貫通孔５を必要とする領域２ａ，２ｄとがある。このため、後者の領域２ａ，２ｄに２個の貫通孔５の内部容積に等しい内部容積を有する大きな内径Ｄの貫通孔５ｂを７個の貫通孔５とほぼ等間隔の位置に１個形成したものである。この結果、領域２ｂ，２ｃと領域２ａ，２ｄとにおける貫通孔５，５ｂ全体の内部容積を、互いにほぼ等しくすることができる。
【００３３】
上記金属板２の表面３と裏面４に、前記樹脂フィルム６，７をラミネートし、且つ前記同様の方法によりプレスし且つ硬化処理することにより、図６（Ｃ）に示すように、表面１２と裏面１３との間における厚みが、殆ど均一になるコア基板１ｂが得られる。コア基板１ｂの図６（Ｃ）中の一点鎖線ａで示す部分に、前記同様にしてスルーホールｈを形成した部分の拡大図を、図７（Ａ）に示す。この際、大径の貫通孔５ｂにおいても、充填された樹脂１０の中心部に同径のスルーホールｈが形成される。
次に、前述した方法により、図７（Ｂ）に示すように、コア基板１ｂの表面１２と裏面１３とに、所定パターンの表面配線層１６と裏面配線層１７とを個別に形成する。
【００３４】
更に、図７（Ｃ）に示すように、コア基板１ｂの表面１２および表面配線層１６の上方に、絶縁層１８，２４および配線層２２，２８を含むビルドアップ層ＢＵなどを形成する。そして、コア基板１ｂの裏面１３および裏面配線層１７の下方に絶縁層１９などを、前記同様の方法により形成することにより、配線基板Ｋ２を得ることができる。この際、表面配線層１６、裏面配線層１７、および配線層２２，２８などは、コア基板１ｂの表面１２および裏面１３の全面における厚みがほぼ均一であるため、平坦に形成することができる。
尚、上記コア基板１ｂの裏面１３の下方にも、上記と同様のビルドアップ層ＢＵをこれと対称にして形成しても良い。
【００３５】
本発明は、以上において説明した形態に限定されるものではない。
前記コア基板１，１ａ，１ｂに用いるコア材は、前記銅合金に限らず、Ｆｅ−Ｎｉ系合金、チタンやその合金、アルミニウムやその合金などからなる金属板としても良い。あるいは、合成樹脂またはこれにガラスフィラなどの無機フィラを含む複合材からなるコア材を用いも良い。
また、前記樹脂フィルムには、絶縁性の樹脂のほか、導電性樹脂からなるものを用いても良い。かかる導電性の樹脂フイルムおよび上記合成樹脂などの絶縁材からなるコア材を併用することにより、かかるコア材の貫通孔にスルーホール導体などを形成することも可能である。
【００３６】
更に、前記ダミー貫通孔５ａを配置する位置は、同時に配置される複数の貫通孔５と互いにほぼ等間隔になる位置とすることが望ましいが、かかる複数のダミー貫通孔５ａをより少ない大きな内径Ｄの貫通孔５ｂに置き換える場合も、同時に配置される複数の貫通孔５からほぼ等距離となる位置に配置するものとする。
また、前記図１（Ａ），（Ｂ）の金属板（コア材）２における各領域２ａ〜２ｄにおける９個の貫通孔５の何れかを、ダミー貫通孔５ａに置き換えても良い。
更に、前記図６（Ａ），（Ｂ）の金属板（コア材）２において、領域２ａ，２ｄに配置する貫通孔５ｂの内径Ｄは、同時に配置する貫通孔５の内径ｄよりも小さくし、且つ置換すべき内部容積の総和に当たる貫通孔５の数よりも多く配置することも可能である。
【００３７】
【発明の効果】
本発明による第１乃至第３の配線基板の製造方法（請求項１〜３）によれば、コア材の全面において複数の貫通孔の分布密度がほぼ平均化し、あるいは、ダミー貫通孔を含む貫通孔の分布密度がほぼ平均化し、更には、コア材の各領域における全貫通孔の内部容積が互いにほぼ等しくなる。このため、前記樹脂をコア材の各貫通孔に圧入し且つ表面および裏面に形成すると、各貫通孔に樹脂が充填され、コア材の表面や裏面にそれぞれ形成される樹脂層の厚みも、全面において均一なコア基板を得ることができる。従って、かかるコア基板を用いることにより、平坦な配線層を含む信頼性の高い配線基板を容易に形成することが可能となる。
【００３８】
また、請求項４の配線基板の製造方法によれば、コア材の各貫通孔に圧入する樹脂の量、表面や裏面に形成する各樹脂層の厚みを、前記の何れかの方法に沿って、容易に制御できる。従って、全面においてほぼ均一な厚みのコア基板を一層確実に得ることが可能となる。
更に、請求項５の配線基板の製造方法によれば、所要の強度を有し、貫通孔内が樹脂で充填され、且つ表面および裏面にそれぞれ平坦な樹脂層が形成された金属板をコア材とするコア基板を確実に製造できる。
【図面の簡単な説明】
【図１】（Ａ）は本発明による第１の製造方法に用いるコア材の平面図、（Ｂ）は（Ａ）中のＢ−Ｂ線に沿った矢視における断面図。
【図２】（Ａ）〜（Ｄ）は第１の製造方法における各工程を示す概略図で、且つ（Ｃ）は（Ｂ）中の一点鎖線部分Ｃの拡大図。
【図３】（Ａ），（Ｂ）は図２（Ｄ）に続く製造工程の概略図または得られた配線基板を示す断面図。
【図４】（Ａ）は本発明による第２の製造方法に用いるコア材の平面図、（Ｂ）は（Ａ）中のＢ−Ｂ線に沿った矢視における断面図、（Ｃ）は得られたコア基板の断面図。
【図５】（Ａ）〜（Ｃ）は図４（Ｃ）に続く各製造工程を示す概略図または得られた配線基板の断面図で、且つ（Ａ）は図４（Ｃ）中の一点鎖線部分ａの拡大図。
【図６】（Ａ）は本発明による第３の製造方法に用いるコア材の平面図、（Ｂ）は（Ａ）中のＢ−Ｂ線に沿った矢視における断面図、（Ｃ）は得られたコア基板の断面図。
【図７】（Ａ）〜（Ｃ）は図６（Ｃ）に続く各製造工程を示す概略図または得られた配線基板の断面図で、且つ（Ａ）は図６（Ｃ）中の一点鎖線部分ａの拡大図。
【図８】（Ａ）〜（Ｅ）は従来の技術によるコア基板の製造工程を示す概略図。
【符号の説明】
１，１ａ，１ｂ…コア基板
２………………金属板（コア材）
２ａ〜２ｄ……領域
３………………表面
４………………裏面
５，５ｂ………貫通孔
５ａ……………ダミー貫通孔
６，７…………樹脂フイルム
８，９…………樹脂層
１０……………樹脂
１４……………スルーホール導体
Ｋ，Ｋ１，Ｋ２…配線基板
Ｄ，ｄ…………内径[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a wiring board including a manufacturing process of a core substrate using a core material as a core material.
[0002]
[Prior art]
In some cases, a metal plate is used as a core material which is a core material of a core substrate serving as a base of a wiring substrate. The inside of the through-hole penetrating between the front surface and the back surface of the metal plate is filled with resin in order to insulate the periphery of a through-hole conductor penetrating coaxially through the center portion. There are the following methods for filling the through hole of the metal plate with a resin.
(1) A method of filling a through-hole with a paste resin by a printing method or a dispensing method.
(2) A method in which a dry type resin film is laminated on the front and back surfaces of a metal plate and pressed along the thickness direction to press-fit the resin into the through holes.
(3) A method in which a semi-cured resin such as a prepreg flows into a through-hole by hot pressing.
[0003]
In the above methods (1) and (2), immediately after the through-hole of the metal plate (core material) is filled with the resin, even if the front and back surfaces of the metal plate are flat, the resin filled thereafter is filled with the resin. When a curing process for curing is performed, dents are generated at positions just above and below the resin in the through holes, respectively, as the resin shrinks during curing.
For example, as shown in FIG. 8A, a metal plate (core material) 40 having a front surface 42 and a back surface 43 and having a plurality of through holes 44 penetrating therebetween and having a thickness of 0.25 mm, In the drawing, the through holes 44 have a dense distribution in the left region 40a, and the through holes 44 have a sparse distribution in the right region 40b. The inside diameter of each through hole 44 is about 0.3 mm.
First, as shown in FIG. 8B, dry type resin films 45 and 46 having a thickness of 60 μm are laminated on the front surface 42 and the rear surface 43 of the metal plate 40.
[0004]
Next, as shown by arrows in FIG. 8B, the resin films 45 and 46 are pressed (by a vacuum hot press or the like) along the thickness direction so as to be pressed against the metal plate 40. As a result, as shown in FIG. 8C, the resin films 45 and 46 become compressed resin layers 47 and 48, and a part of the resin 49 is pressed into the plurality of through holes 44, The inside of the through hole 44 is filled.
Then, the metal plate 40 on which the resin layers 47 and 48 and the resin 49 are formed is heated to cure the resin layers 47 and 48 and the like.
As a result, as shown in FIG. 8D, a depression 50 is formed on the surfaces of the resin layers 47 and 48 immediately above and below the through hole 44 with the curing shrinkage of the resin 49.
[0005]
As shown in FIG. 8E, the thickness of the resin layers 47 and 48 formed on the front surface 42 and the rear surface 43 of the metal plate 40 due to the recess 50 is small in the region 40a where the distribution of the through holes 4 is dense. Since the hole 44 is filled with a large amount of the resin 49, the thickness becomes thin. On the other hand, in the region 40b where the density of the through holes 44 is low, the through holes 44 are filled with a small amount of the resin 49, so that the through holes 44 tend to be thick. As a result, as shown in FIG. 8E, when the thickness between the front surface 52 and the back surface 53 of the core substrate k varies, the front surface wiring layer and the back surface wiring layer formed on the front surface 52 and the back surface 53 are formed. In addition to the distortion, the flatness of the insulating layer and the build-up wiring layer formed thereon is impaired. For this reason, there has been a problem that the reliability of the obtained wiring board is impaired.
[0006]
[Problems to be solved by the invention]
The present invention solves the problems in the conventional technique described above, and fills each of the through-holes of a core material having a plurality of through-holes formed between the front surface and the back surface with a resin, and fills the front surface and the back surface with the resin. It is another object of the present invention to provide a method of manufacturing a wiring board including a manufacturing step of a core substrate capable of manufacturing a core substrate having a resin layer formed thereon with a substantially uniform thickness.
[0007]
[Means for Solving the Problems]
The present invention solves the above problems, as a result of intensive studies and investigations by the inventors, the average of the amount of resin filled in the plurality of through holes in the core material over the entire area of the core material, It was made with the idea.
That is, the first method of manufacturing a wiring board according to the present invention (claim 1) is directed to a method of manufacturing a core material having a front surface and a back surface and a plurality of through holes penetrating between the front surface and the back surface. Forming a resin layer on each of the front and back surfaces of the material, and simultaneously filling and filling the through holes with a resin; and manufacturing the core substrate. In this step, a plurality of through holes penetrating the core material are viewed in plan. Is substantially averaged over the entire surface of the front and back surfaces of the core material.
[0008]
According to this, the plurality of through holes penetrating the core material have a distribution density substantially averaged over the entire surface of the core material, that is, the number of through holes arranged in any region of the core material is substantially the same. Is placed. For this reason, when a resin film or the like is disposed on the front and back surfaces of the core material and pressed along the thickness direction, the resin is pressed into each through hole and the front surface formed on the front and back surfaces of the core material is pressed. The thickness of the resin layer and the back surface resin layer can be made substantially uniform over the entire surface of the core material. Therefore, by using a core substrate having such a core material, a filling resin, a surface resin layer, and a back surface resin layer, the front surface wiring layer and the back surface wiring layer formed on the front surface and the back surface of the core substrate are formed on these surfaces rather than the base. It is easy to obtain a highly reliable wiring board in which the formed insulating layer and build-up wiring layer are also formed flat.
The core material includes a resin plate, a resin plate on which metal foils on the front and rear surfaces are adhered, in addition to a metal plate described later. In addition, the above resin includes a conductive resin in addition to an insulating resin.
[0009]
Further, the second method of manufacturing a wiring board according to the present invention (claim 2) is characterized in that the core material has a front surface and a back surface and has a plurality of through holes penetrating between the front surface and the back surface. Forming a resin layer on each of the front and back surfaces of the material, including a core substrate manufacturing process of filling and filling the resin in the through holes at the same time. In a region where the through-hole formed through the resin is dense, a dummy through-hole in which the through-hole conductor does not penetrate the inside later is formed or a little, and a through-hole conductor penetrates the resin later inside. In a region where the formed through-hole is sparse, a large number of dummy through-holes in which the through-hole conductor does not penetrate the inside will be formed.
[0010]
According to this, in the area where the through-holes are dense in the core material, the dummy through-holes are not formed or only slightly formed, and in the area where the through-holes are sparse, many dummy through-holes are formed. The distribution density of the through-holes including the dummy through-holes is substantially averaged over the entire surface of the core material. That is, the through holes including the dummy through holes are formed in substantially the same number in any region of the core material.
Therefore, as described above, when the resin is pressed into each through-hole including the dummy through-hole of the core material and the resin is formed on the front surface and the back surface, the resin is filled into each through-hole and the front surface and the back surface of the core material are filled. It is possible to obtain a core substrate in which the thickness of the resin layer formed is also substantially uniform over the entire surface of the core material. By using such a core substrate, the above-described highly reliable wiring substrate can be easily formed.
[0011]
Furthermore, the third method of manufacturing a wiring board according to the present invention (claim 3) is characterized in that the core material has a front surface and a back surface and a plurality of through holes penetrating between the front surface and the back surface. Forming a resin layer on each of the front and back surfaces of the material, and simultaneously filling and filling the through holes with a resin; and manufacturing a core substrate in which the distribution density of the plurality of through holes is sparse. The inner volume of the hole and the inner diameter of the through hole in the region of the core material where the distribution density is sparse so that the distribution density of the through hole is approximately equal to the inner volume of the through hole in the region of the core material where the distribution density is dense. A difference is provided between the distribution density and the inner diameter of the through hole in the region of the core material having a dense distribution density.
[0012]
According to this, in a region where the through holes are dense in the core material, for example, a through hole having a small inner diameter is formed, while in a region where the through holes are sparse, a through hole having a large inner diameter is formed. The internal volumes of all the through holes in the region are substantially equal to each other. For this reason, as described above, when the resin is pressed into each through hole of the core material and the resin is formed on the front surface and the back surface, the resin is filled into each through hole and the surface formed on the front surface and the back surface of the core material is formed. A core substrate in which the thickness of the resin layer and the back surface resin layer is substantially uniform over the entire surface of the core material can be obtained. Therefore, by using such a core substrate, it is possible to easily form the above-described highly reliable wiring substrate.
[0013]
In the present invention, the step is performed by individually laminating resin films on the front and back surfaces of the core material, respectively, and pressing the pair of resin films along the thickness direction of the core material. A method for manufacturing a wiring board (claim 4) is also included. According to this, the amount of resin pressed into each through hole in the core material and the thickness of each resin layer formed on the front surface and the back surface can be easily adjusted according to any of the first to third methods described above. Can be controlled. Therefore, it is possible to more reliably obtain a core substrate having a substantially uniform thickness over the entire surface.
[0014]
Furthermore, the present invention also includes a method for manufacturing a wiring board, wherein the core material is a metal plate having the front surface, the back surface, and a through hole.
According to this, it is possible to reliably manufacture a core substrate having a required strength, a core material made of a metal plate in which the inside of the through hole is filled with a resin, and a flat resin layer formed on the front and back surfaces. Manufacture of a robust wiring board including a flat front surface wiring layer and a back surface wiring layer formed on the front surface and the back surface of the core substrate, and a flat insulating layer and a build-up wiring layer formed above at least one of them. It is possible to do.
In addition, a copper alloy such as Cu-2.3 wt% Fe-0.03 wt% P (194 alloy), pure copper, oxygen-free copper, Fe-42 wt% Ni (42 alloy), Fe-36 wt% Plates made of Fe—Ni alloys such as Ni (invar), other steel types, titanium and its alloys, and aluminum and its alloys are included.
[0015]
In other words, in the present invention, after the above-described step, a step of individually forming a front surface wiring layer and a back surface wiring layer on the front surface and the back surface of the obtained core substrate, and at least one of the front surface and the back surface of the core substrate Above, a step of forming a build-up layer including a plurality of insulating layers and a plurality of wiring layers located therebetween may also include a method of manufacturing a wiring board. In this case, it is possible to reliably manufacture the above-described highly reliable broken line substrate.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
1A and 1B are a plan view and a cross-sectional view of a metal plate 2 as a core material used in a first method for manufacturing a wiring board according to the present invention. The metal plate 2 is made of, for example, the copper alloy (194 alloy) having a thickness of 0.25 mm, and has a front surface 3 and a back surface 4 as shown in FIGS. 1 (A) and 1 (B). A plurality of through-holes 5 having an inner diameter of about 0.3 mm penetrate therethrough. The plurality of through holes 5 are formed by punching the metal plate 2 or by laser processing, drilling, or etching.
[0017]
As shown by the broken lines in FIG. 1A, the metal plate 2 is divided into four regions 2a to 2d in plan view, and among the upper left region 2a and the lower left region 2c, nine through holes are provided. 5 are arranged at the respective intersections of the lattice pattern.
On the other hand, in the upper right region 2b and the lower right region 2d of the metal plate 2, nine through-holes 5 are arranged at positions where a slightly flat checkerboard pattern is formed.
That is, as shown in FIGS. 1A and 1B, in the metal plate 2, nine through holes 5 having the same inner diameter are formed at substantially equal intervals in all regions 2a to 2d. The distribution density of the through holes 5 in these regions 2a to 2d is averaged.
[0018]
As shown in FIG. 2A, a dry type resin made of an epoxy resin having a thickness of about 20 to 80 μm (40 μm in the present embodiment) is provided on all the regions 2 a to 2 d on the front surface 3 and the back surface 4 of the metal plate 2. The films 6 and 7 are laminated (laminated).
Next, as shown by arrows in FIG. 2A, the resin films 6 and 7 are pressed along a thickness direction of the metal plate 2 by a hot press (not shown) or the like.
As a result, as shown in FIG. 2 (B), the resin films 6 and 7 are compressed into resin layers 8 and 9 which are in close contact with the front surface 3 and the back surface 4 of the metal plate 2, and a part of the resin films is penetrated. The resin enters the holes 5 and 5 and becomes the resins 10 and 10 that fill them.
[0019]
Next, the metal plate 2 having the resin layers 8 and 9 and the resin 10 in the through-holes 5 is inserted into a heating furnace (not shown), and a hardening (curing) process of heating to about 150 ° C. for about 60 minutes in the atmosphere is performed. . FIG. 2 (C) is an enlarged view of a portion indicated by a dashed line C in FIG. 2 (B) of the metal plate 2 and the like after the hardening process.
As described above, in the entire regions 2a to 2d of the metal plate 2, nine through-holes 5 are formed at substantially equal intervals to each other, so that as shown in FIG. Has a substantially uniform thickness between the front surface 12 and the back surface 13.
[0020]
Hereinafter, a manufacturing process of the wiring board K using the core substrate 1 will be described.
FIG. 2 (D) shows that the central portions of the through holes 5 and 5 of the metal plate 2 built in the core substrate 1 are irradiated with, for example, a carbon dioxide gas laser so as to extend along the central portions of the resin layers 8 and 9 and the resin 10. Next, a step of forming a through hole h penetrating between the front surface 12 and the back surface 13 of the core substrate 1 will be described. The inside diameter of the through hole h is about 150 μm. The through hole h may be formed by using a small diameter drill instead of the laser.
Next, after coating a plating catalyst containing Pd on the front surface 12, the back surface 13, and the inner walls of the through holes h, h of the core substrate 1, electroless copper plating and electrolytic copper plating are applied to the entire surface. As a result, as shown in FIG. 3A, a cylindrical through-hole conductor 14 is formed along the inner wall of each through-hole h. A conductive or non-conductive filling resin 15 is formed in the hollow portion of the through-hole conductor 14. Thereafter, copper plating is performed on the front surface 12 and the back surface 13 of the core substrate 1.
[0021]
Next, a resin film (not shown) made of a photosensitive resin and having a thickness of about 20 to 30 μm is attached onto the copper plating films formed on the front surface 12 and the back surface 13 of the core substrate 1. After a mask (not shown) having a predetermined pattern is placed on the film, the film is exposed and developed (photography technology) to form an etching resist (not shown) having a predetermined pattern. I do. Further, the copper plating film exposed from between the patterns of the resist is etched by contacting with the developing solution via the resist.
As a result, as shown in FIG. 3A, a front surface wiring layer 16 and a rear surface wiring layer 17 are formed on the front surface 12 and the rear surface 13 of the core substrate 1 according to the above-mentioned pattern, and these are formed by through-hole conductors. 14 is connected to the upper or lower end, and both ends of the filling resin 15 are plated with a lid.
[0022]
Further, as shown in FIG. 3B, an insulating layer 18 made of an epoxy resin film containing an inorganic filler such as silica filler and having a thickness of 30 μm is formed on the surface wiring layer 16. Photolithography or laser processing (using a carbon dioxide laser or the like) is performed on a predetermined position in the insulating layer 18 to form a plurality of via holes (not shown). The surface wiring layer 16 is exposed at the bottom of the via hole.
Next, after a plating catalyst similar to the above is applied to the surface of the insulating layer 18 and the inner wall surface of the via hole, electroless copper plating and electrolytic copper plating are performed, and a copper plating film is formed on the surface of the insulating layer 24. As shown in FIG. 3B, a via (filled via) conductor 20 is formed in the via hole.
[0023]
Next, an etching resist similar to the above is formed on the insulating layer 18 on which the copper plating film is formed, and development is performed. As a result, a wiring layer (build-up wiring) 22 having a predetermined pattern is formed on the insulating layer 18 as shown in FIG. This wiring layer 22 is connected to surface wiring layer 16 via via conductor 20.
In the same manner as described above, as shown in FIG. 3B, the insulating layer 24, the via conductor 26, and the wiring layer 28 are formed. The via conductor 26 connects the wiring layers 22 and 28, and the insulating layers 18 and 24 and the wiring layers 22 and 28 form a build-up layer BU.
[0024]
Further, as shown in FIG. 3B, an uppermost insulating layer (solder resist layer) 30 having a thickness of 20 μm is formed on the wiring layer 28. A solder bump 34 projecting higher than the first main surface 32 from an appropriate position on the wiring layer 28 penetrates through the insulating layer 30 via a Ni-Au layer (not shown).
The solder bump 34 is made of a low melting point alloy such as Sn-Ag, Pb-Sn, Sn-Ag-Cu, Sn-Cu, or Sn-Zn (in this embodiment, Sn-Ag). It is individually connected to connection terminals of an IC chip (electronic component) (not shown) mounted on one main surface 32. The plurality of solder bumps 34 and the connection terminals of the IC chip are buried and protected by an underfill material.
[0025]
On the other hand, as shown in FIG. 3B, a back wiring layer 17 having a predetermined pattern is formed on the back surface 13 of the core substrate 1 in the same manner as described above, and an insulating layer (solder resist layer) similar to the above is formed thereunder. ) 19 is formed. The wiring 21 extending from the back wiring layer 17 is located on the bottom surface of the opening 25 that opens to the second main surface 23 side in the insulating layer 19. The surface of the wiring 21 is coated with Ni plating and Au plating, and is used as a connection terminal to a printed circuit board such as a motherboard (not shown).
[0026]
Thus, the wiring board K as shown in FIG. 3B is manufactured. Since the wiring board K uses the core substrate 1 having the flat surface 12, the surface wiring layer 16 formed on the surface 12 and the wiring layer 22 in the build-up layer BU formed thereon are formed. , 28 are formed flat. In addition, the thicknesses of the insulating layers 18 and 24 do not vary and are averaged. Therefore, according to the manufacturing method of the present invention, it is possible to reliably manufacture the core substrate 1 having the flat front surface 12 and the rear surface 13 and to reliably manufacture the wiring substrate K using the core substrate 1 with high reliability. It becomes possible.
Note that a build-up layer including a plurality of insulating layers and a plurality of wiring layers may be formed below the back surface 13 of the core substrate 1 symmetrically with the build-up layer BU.
[0027]
FIGS. 4A and 4B are a plan view and a sectional view of a metal plate (core material) 2 used in the second method for manufacturing a wiring board according to the present invention. The metal plate 2 has the same material and thickness as described above, and as shown in FIGS. 4A and 4B, an inner diameter formed by the same method as described above between the front surface 3 and the back surface 4. A plurality of through holes 5 of about 0.3 mm penetrate.
As shown by the broken line in FIG. 4A, the metal plate 2 is divided into four regions 2a to 2d in plan view, and nine through holes are formed in the upper right region 2b and the lower left region 2c. 5 are arranged at the respective intersections of the lattice pattern.
[0028]
On the other hand, in the upper left region 2a and the lower right region 2d of the metal plate 2, eight through holes 5 are arranged at positions forming a square. A dummy through-hole 5 a through which the through-hole conductor does not penetrate is formed inside the area surrounded by these through-holes 5. The inside diameter of the dummy through hole 5a is the same as the inside diameter of the through hole 5. Therefore, in the regions 2a and 2d including the dummy through holes 5a and the eight through holes 5, the through holes 5 and 5a having the same internal volume as the regions 2b and 2c having the nine through holes 5 are formed. I have. That is, in the metal plate 2 shown in FIGS. 4A and 4B, the through holes 5 and 5a having the same number and the same internal volume are formed uniformly in all the regions 2a to 2d.
The inner diameter of the dummy through-hole 5a is not limited to the above-described embodiment in which the inner diameter of the through-hole 5 is the same, and may be larger or smaller than the through-hole 5.
[0029]
By laminating the resin films 6 and 7 on the front surface 3 and the back surface 4 of the metal plate 2 and pressing and curing the same by the same method as described above, as shown in FIG. A core substrate 1a having a substantially uniform thickness with the back surface 13 is obtained. FIG. 5A is an enlarged view of a portion of the core substrate 1a in which a through hole h is formed in a portion indicated by a dashed line a in FIG. At this time, as shown in FIG. 5A, the through hole h is not formed in the resin 10 filled in the dummy through hole 5a.
Next, as shown in FIG. 5B, the front surface wiring layer 16 and the rear surface wiring layer 17 having a predetermined pattern are individually formed on the front surface 12 and the rear surface 13 of the core substrate 1a by the method described above.
[0030]
Further, as shown in FIG. 5C, a buildup layer BU including insulating layers 18 and 24 and wiring layers 22 and 28 is formed above the surface 12 and the surface wiring layer 16 of the core substrate 1a. Then, an insulating layer 19 and the like are formed below the back surface 13 and the back surface wiring layer 17 of the core substrate 1a by the same method as described above. As a result, the wiring board K1 shown in FIG. 5C can be obtained. At this time, the front surface wiring layer 16, the rear surface wiring layer 17, and the wiring layers 22 and 28 can be formed flat because the thickness of the entire surface 12 and the rear surface 13 of the core substrate 1a is substantially uniform.
The same build-up layer BU as described above may be formed symmetrically below the back surface 13 of the core substrate 1a.
[0031]
FIGS. 6A and 6B are a plan view and a sectional view of a metal plate (core material) 2 used in the third method of manufacturing a wiring board according to the present invention. The metal plate 2 has the same material and thickness as described above, and as shown in FIGS. 6A and 6B, an inner diameter d formed by the same method as described above between the front surface 3 and the back surface 4. Have a plurality of through holes 5 of about 0.30 mm.
As shown by the broken line in FIG. 6A, the metal plate 2 is divided into four regions 2a to 2d in plan view, and among the four regions 2a to 2d at the upper right and the region 2c at the lower left, nine through holes are formed. The holes 5 are arranged so as to be located at respective intersections of the lattice pattern.
On the other hand, in the metal plate 2, in the upper left region 2a and the lower right region 2d, seven through-holes 5 are arranged at positions forming a U-shape. One through hole 5b having an inner diameter D of about 0.42 mm is formed substantially at the center of the inside surrounded by these through holes 5. The inner diameter D of the through hole 5b is about 1.4 times the inner diameter d of the through hole 5, and there is a difference of about 0.1 mm between the inner diameter D and the inner diameter d.
[0032]
That is, the internal volume of the through hole 5b is about twice the internal volume of the through hole 5. Therefore, the total internal volume of the nine through-holes 5 in the region 2b and the region 2c and the internal volume of the seven through-holes 5 and one through-hole 5b in the region 2a and the region 2d are: , Are almost equal. In other words, the metal plate 2 has regions 2b and 2c requiring nine through holes 5 and regions 2a and 2d requiring eight through holes 5. Therefore, in the latter regions 2a and 2d, one through hole 5b having a large inner diameter D having an internal volume equal to the internal volume of the two through holes 5 is formed at a position substantially equidistant from the seven through holes 5. Things. As a result, the internal volumes of the entire through holes 5, 5b in the regions 2b, 2c and the regions 2a, 2d can be made substantially equal to each other.
[0033]
By laminating the resin films 6 and 7 on the front surface 3 and the back surface 4 of the metal plate 2 and pressing and curing the same by the same method as described above, as shown in FIG. A core substrate 1b having a substantially uniform thickness with the back surface 13 is obtained. FIG. 7A is an enlarged view of a portion where the through hole h is formed in the same manner as described above in the portion of the core substrate 1b indicated by the alternate long and short dash line a in FIG. 6C. At this time, a through hole h having the same diameter is formed at the center of the filled resin 10 even in the large-diameter through hole 5b.
Next, as shown in FIG. 7B, the front surface wiring layer 16 and the rear surface wiring layer 17 having a predetermined pattern are individually formed on the front surface 12 and the rear surface 13 of the core substrate 1b by the method described above.
[0034]
Further, as shown in FIG. 7C, a build-up layer BU including insulating layers 18 and 24 and wiring layers 22 and 28 is formed above the surface 12 and the surface wiring layer 16 of the core substrate 1b. Then, the wiring substrate K2 can be obtained by forming the insulating layer 19 and the like below the back surface 13 and the back surface wiring layer 17 of the core substrate 1b by the same method as described above. At this time, the front surface wiring layer 16, the back surface wiring layer 17, and the wiring layers 22 and 28 can be formed flat because the thickness of the entire surface 12 and the back surface 13 of the core substrate 1b is substantially uniform.
The same build-up layer BU as described above may be formed below the back surface 13 of the core substrate 1b symmetrically.
[0035]
The present invention is not limited to the embodiments described above.
The core material used for the core substrates 1, 1a, and 1b is not limited to the copper alloy, and may be a metal plate made of an Fe—Ni alloy, titanium or its alloy, aluminum or its alloy, or the like. Alternatively, a core material made of a synthetic resin or a composite material containing an inorganic filler such as a glass filler may be used.
The resin film may be made of a conductive resin in addition to an insulating resin. By using together such a conductive resin film and a core material made of an insulating material such as the above synthetic resin, it is also possible to form a through-hole conductor or the like in a through hole of the core material.
[0036]
Further, it is preferable that the dummy through-holes 5a are arranged at positions substantially equidistant from the plurality of through-holes 5 arranged at the same time. When replacing with the through-hole 5b, it is assumed that the through-hole 5b is arranged at a position which is substantially equidistant from the plurality of through-holes 5 arranged at the same time.
Further, any one of the nine through holes 5 in each of the regions 2a to 2d in the metal plate (core material) 2 in FIGS. 1A and 1B may be replaced with a dummy through hole 5a.
Further, in the metal plate (core material) 2 shown in FIGS. 6A and 6B, the inside diameter D of the through holes 5b arranged in the regions 2a and 2d is made smaller than the inside diameter d of the through holes 5 arranged at the same time. It is also possible to arrange more than the number of through holes 5 corresponding to the sum of the internal volumes to be replaced.
[0037]
【The invention's effect】
According to the first to third methods of manufacturing a wiring board according to the present invention (claims 1 to 3), the distribution density of the plurality of through holes is substantially averaged over the entire surface of the core material, or the through holes including the dummy through holes are provided. The distribution density of the holes is substantially averaged, and the internal volumes of all the through holes in each region of the core material are substantially equal to each other. For this reason, when the resin is press-fitted into each through hole of the core material and formed on the front surface and the back surface, the resin is filled into each through hole, and the thickness of the resin layer formed on the front surface and the back surface of the core material also increases. And a uniform core substrate can be obtained. Therefore, by using such a core substrate, a highly reliable wiring substrate including a flat wiring layer can be easily formed.
[0038]
According to the method of manufacturing a wiring board according to claim 4, the amount of the resin press-fitted into each through-hole of the core material and the thickness of each resin layer formed on the front surface and the back surface are adjusted according to any one of the methods described above. , Easy to control. Therefore, it is possible to more reliably obtain a core substrate having a substantially uniform thickness over the entire surface.
Further, according to the method of manufacturing a wiring board according to claim 5, a metal plate having a required strength, a through-hole filled with a resin, and a flat resin layer formed on each of a front surface and a back surface is formed of a core material. Can be reliably manufactured.
[Brief description of the drawings]
FIG. 1A is a plan view of a core material used in a first manufacturing method according to the present invention, and FIG. 1B is a cross-sectional view taken along line BB in FIG.
FIGS. 2A to 2D are schematic views showing respective steps in a first manufacturing method, and FIG. 2C is an enlarged view of a dashed-dotted line portion C in FIG.
FIGS. 3A and 3B are schematic views of a manufacturing process following FIG. 2D or sectional views showing the obtained wiring board;
4A is a plan view of a core material used in the second manufacturing method according to the present invention, FIG. 4B is a cross-sectional view taken along line BB in FIG. 4A, and FIG. Sectional drawing of the obtained core board.
5 (A) to 5 (C) are schematic views showing respective manufacturing steps following FIG. 4 (C) or sectional views of the obtained wiring board, and FIG. 5 (A) is a point in FIG. 4 (C). The enlarged view of the dashed line part a.
6A is a plan view of a core material used in a third manufacturing method according to the present invention, FIG. 6B is a cross-sectional view taken along line BB in FIG. 6A, and FIG. Sectional drawing of the obtained core board.
7 (A) to 7 (C) are schematic views showing respective manufacturing steps following FIG. 6 (C) or sectional views of the obtained wiring board, and FIG. 7 (A) is a point in FIG. 6 (C). The enlarged view of the dashed line part a.
8 (A) to 8 (E) are schematic views showing steps of manufacturing a core substrate according to a conventional technique.
[Explanation of symbols]
1, 1a, 1b ... core substrate
2. Metal plate (core material)
2a to 2d ... area
3 ......... surface
4 …………… Back
5,5b ... through-hole
5a ………… Dummy through hole
6,7 ...... Resin film
8, 9 ... resin layer
10 ............ Resin
14. Through-hole conductor
K, K1, K2 ... wiring board
D, d ……… Inner diameter

Claims

表面および裏面を有し且つかかる表面と裏面との間を貫通する複数の貫通孔を有するコア材に対し、
上記コア材の表面および裏面に樹脂層をそれぞれ形成し、同時に上記貫通孔内に樹脂を充填し穴埋めするコア基板の製造工程を含み、
上記工程において、上記コア材を貫通する複数の貫通孔の平面視における分布密度が、かかるコア材の表面および裏面の全面において、ほぼ平均化している、
ことを特徴とする配線基板の製造方法。For a core material having a front surface and a back surface and having a plurality of through holes penetrating between the front surface and the back surface,
Forming a resin layer on the front surface and the back surface of the core material, respectively, including a manufacturing process of a core substrate to fill and fill the resin in the through hole at the same time,
In the step, the distribution density in a plan view of the plurality of through-holes penetrating the core material is substantially averaged over the entire surface and the back surface of the core material.
A method for manufacturing a wiring board, comprising:

表面および裏面を有し且つかかる表面と裏面との間を貫通する複数の貫通孔を有するコア材に対し、
上記コア材の表面および裏面に樹脂層をそれぞれ形成し、同時に上記貫通孔内に樹脂を充填し穴埋めするコア基板の製造工程を含み、
上記コア材の上記表面から見て、追って内側をスルーホール導体が上記樹脂を貫通して形成される貫通孔が密な領域では、追って内側をスルーホール導体が貫通しないダミー貫通孔を形成しないかまたは少し形成すると共に、
追って内側をスルーホール導体が上記樹脂を貫通して形成される貫通孔が疎な領域では、追って内側をスルーホール導体が貫通しないダミー貫通孔を多く形成する、ことを特徴とする配線基板の製造方法。For a core material having a front surface and a back surface and having a plurality of through holes penetrating between the front surface and the back surface,
Forming a resin layer on the front surface and the back surface of the core material, respectively, including a manufacturing process of a core substrate to fill and fill the resin in the through hole at the same time,
When viewed from the surface of the core material, in a region where a through-hole conductor formed through the resin is densely formed through the resin, a dummy through-hole in which the through-hole conductor does not penetrate the inside is formed. Or with a little forming,
In a region where through holes formed by penetrating the resin through-hole conductors on the inner side are sparsely formed, a large number of dummy through-holes are formed without the through-hole conductors penetrating on the inner side. Method.

表面および裏面を有し且つかかる表面と裏面との間を貫通する複数の貫通孔を有するコア材に対し、
上記コア材の表面および裏面に樹脂層をそれぞれ形成し、同時に上記貫通孔内に樹脂を充填し穴埋めするコア基板の製造工程を含み、
上記複数の貫通孔の分布密度が疎なコア材の領域における貫通孔の内部容積と、上記貫通孔の分布密度が密なコア材の領域の貫通孔の内部容積と、がほぼ等しくなるように、上記分布密度が疎なコア材の領域における貫通孔の内径と、上記分布密度が密なコア材の領域の貫通孔の内径との間に、差を設けている、
ことを特徴とする配線基板の製造方法。For a core material having a front surface and a back surface and having a plurality of through holes penetrating between the front surface and the back surface,
Forming a resin layer on the front surface and the back surface of the core material, respectively, including a manufacturing process of a core substrate to fill and fill the resin in the through hole at the same time,
The distribution density of the plurality of through-holes is such that the internal volume of the through-holes in the region of the sparse core material and the distribution density of the through-holes are substantially equal to the internal volume of the through-holes in the region of the dense core material. A difference is provided between the inner diameter of the through hole in the region of the core material having a sparse distribution density and the inner diameter of the through hole in the region of the core material having a dense distribution density.
A method for manufacturing a wiring board, comprising:

前記工程は、前記コア材の表面および裏面にそれぞれ樹脂フィルムを個別に積層し、かかる一対の樹脂フィルムを上記コア材の厚み方向に沿って押圧することにより行われる、
ことを特徴とする請求項１乃至３の何れか一項に記載の配線基板の製造方法。The step is performed by individually laminating a resin film on each of the front surface and the back surface of the core material, and pressing the pair of resin films along the thickness direction of the core material.
The method for manufacturing a wiring board according to claim 1, wherein:

前記コア材は、前記表面、裏面、および貫通孔を有する金属板である、
ことを特徴とする請求項１乃至４の何れか一項に記載の配線基板の製造方法。The core material is a metal plate having the front surface, the back surface, and a through hole,
The method for manufacturing a wiring board according to claim 1, wherein: