JP3719093B2

JP3719093B2 - Method for drilling non-through holes in metal foil-clad laminates

Info

Publication number: JP3719093B2
Application number: JP2000089910A
Authority: JP
Inventors: 建吾山野内; 孝兵小寺; 俊治高田
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2000-03-28
Filing date: 2000-03-28
Publication date: 2005-11-24
Anticipated expiration: 2020-03-28
Also published as: JP2001277426A

Description

【０００１】
【発明の属する技術分野】
本発明は、炭酸ガスレーザの照射で金属箔張積層板に非貫通孔を穿孔する方法に関するものである。
【０００２】
【従来の技術】
多層プリント基板において、下層の回路８を形成する導体と、上層の回路８を形成する導体との間には絶縁層２が設けられている。そしてこの絶縁層２は以下のようにして形成されているものである。すなわち、まずガラスクロス等のガラスで形成される基材４に、エポキシ樹脂等の樹脂をワニスとして含浸させ、半硬化させることによって樹脂含浸基材１を作製する。次にこの樹脂含浸基材１の一方の面に金属箔３を重ねると共に、他方の面を予め回路８が形成された下層の導体に対向して重ね、加熱加圧等を行うことによって積層成形する。この後、樹脂含浸基材１に重ねた金属箔３に回路８を形成することによって上層の回路８を形成する導体が形成されるものである。このように絶縁層２は樹脂含浸基材１からなるものであり、樹脂で形成される層内にこれと平行して基材４が存在しているものである。
【０００３】
そして、この上下の導体の導通をとるために、下層の導体を被覆する絶縁層２の一部を除去し、底面にこの導体が露出される非貫通孔７を穿孔し、この非貫通孔７の内壁面に無電解めっき及び電解めっきを施し、めっき層を設けてビアホール１１が形成されるものである。
【０００４】
上記のような非貫通孔７を穿孔するにあたって、炭酸ガスレーザＬを利用する方法が広く行われている。すなわち、予め絶縁層２を被覆する上層の導体にエッチングレジストの塗布、露光、現像、エッチング等を順に施して開口部を形成しておき、次いで絶縁層２の表面が露出したこの開口部に向けて炭酸ガスレーザＬを照射すると、下層の回路８を形成する導体が底面に露出する非貫通孔７を穿孔することができるものである。また、光学系で炭酸ガスレーザＬのビーム径を絞ることで所望の径を有する非貫通孔７を穿孔することができるものである。そして、穿孔後は上記と同様にめっき処理を施してビアホール１１を形成し、上下の導体の導通をとるものである。
【０００５】
【発明が解決しようとする課題】
しかしながら、図５（ａ）に示す従来例のようにガラスクロス等の基材４が絶縁層２の一部として存在していると、炭酸ガスレーザＬを利用して非貫通孔７を穿孔した場合、図５（ｂ）に示すように完全に除去されなかった基材４が非貫通孔７の内壁面から突出した突出部９として残存することが多く見られる。これは穿孔時に絶縁層２内の樹脂に比べて、基材４の方が炭酸ガスレーザＬの熱エネルギーをより多く必要とするが、実際には樹脂及び基材４が受ける熱エネルギーにはあまり差が無く、これにより基材４が加工され難くなるためであると考えられる。
【０００６】
そして、このように突出部９を残したまま無電解めっきや電解めっきを施してしまうと、この突出部９に形成されるめっき層がその他の箇所に形成されるものよりも早く成長し、非貫通孔７の開口部を閉塞するなどして内壁面にめっき層を均一に設けることが困難となって、めっき付き回り性が悪化するものであった。
【０００７】
本発明は上記の点に鑑みてなされたものであり、炭酸ガスレーザＬの照射によってめっき付き回り性の良好な非貫通孔７を金属箔張積層板に穿孔する方法を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
本発明の請求項１に係る金属箔張積層板への非貫通孔の穿孔方法は、樹脂含浸基材１によって絶縁層２が形成されると共に、絶縁層２の表面に金属箔３を重ね合わせて積層成形される金属箔張積層板であって、基材４の厚み方向の中心５が絶縁層２の厚み方向の中心６より金属箔３側に偏在されていると共に、基材４の厚み方向の中心と基材４が偏在する側の絶縁層２の表面との距離が絶縁層２全体の厚みの１／７〜３／７であるものに非貫通孔７を穿孔するにあたって、上記金属箔張積層板の基材４を偏在させた側と反対側の絶縁層２の表面に炭酸ガスレーザＬを照射して絶縁層２に非貫通孔７を形成することを特徴とするものである。
【０００９】
また本発明の請求項２に係る金属箔張積層板への非貫通孔の穿孔方法は、樹脂含浸基材１によって絶縁層２が形成されると共に、絶縁層２の片側表面に金属箔３を重ね合わせて積層成形される金属箔張積層板であって、基材４の厚み方向の中心５が絶縁層２の厚み方向の中心６より金属箔３側に偏在されていると共に、基材４の厚み方向の中心と基材４が偏在する側の絶縁層２の表面との距離が絶縁層２全体の厚みの１／７〜３／７であるものに非貫通孔７を穿孔するにあたって、上記金属箔張積層板の基材４を偏在させた側と反対側の絶縁層２の表面に炭酸ガスレーザＬを照射して絶縁層２に非貫通孔７を形成することを特徴とするものである。
【００１０】
また請求項３の発明は、請求項１において、絶縁層２の厚みが２０〜２００μｍであることを特徴とするものである。
【００１１】
また請求項４の発明は、請求項２において、絶縁層２の厚みが２０〜２００μｍであることを特徴とするものである。
【００１３】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
【００１４】
本発明において基材４としては、特に限定されるものではなく、例えば、ガラスクロス、ガラスマット、ガラスペーパーなどのガラス基材を用いることができる。
【００１５】
また樹脂としては、特に限定されるものではなく、例えば、エポキシ樹脂、フェノール樹脂、ポリイミド樹脂などを用いることができる。このような樹脂に硬化剤、硬化促進剤、添加剤などを混合し、必要に応じて水や有機溶剤で希釈することによってワニスを調製することができる。
【００１６】
樹脂含浸基材１を作製するにあたって、従来法と同様にまず上記の基材４にワニスを含浸させる。樹脂含有率は樹脂含浸基材１の全量に対して３０〜８０質量％となるように含浸させることが好ましい。次にワニスが含浸された基材４を乾燥させるものであるが、このとき図２に示すように基材４を境界として、基材４の一方の面に形成される樹脂層１０の厚みが他方の面に形成される樹脂層１０の厚みよりも厚くなるようにして乾燥させ、半硬化状態とするものであり、基材４はその厚み方向の中心５が樹脂含浸基材１の厚み方向の中心６より一方の表面側に偏在しているものである。
【００１７】
ここで、ワニスが含浸された基材４を上記のように乾燥させるにあたって、乾燥機としては、横型乾燥機を用いるのが好ましい。この横型乾燥機を用いると、未硬化の樹脂含浸基材１を横型乾燥機内を略水平方向に送って乾燥する際、未硬化のワニスが重力により全体として下方へ移動するので、このような状態で乾燥させて半硬化状態とすると、基材４を境界として、基材４の下面に形成される樹脂層１０の厚みが上面に形成される樹脂層１０の厚みよりも厚い樹脂含浸基材１が作製されるものである。なお、温度や時間などのワニスの硬化条件は適宜選定することができる。
【００１８】
一方、乾燥機として縦型乾燥機を用いると、この縦型乾燥機は未硬化の樹脂含浸基材１を略鉛直方向に移動させつつ乾燥させるものであるから、上記のように基材４の一方の面に設けられる樹脂層１０と、他方の面に設けられる樹脂層１０との厚みを変化させることは困難であり、基材４の両面に設けられる樹脂層１０の厚みは略等しくなるものである。
【００１９】
図１（ｂ）は、本発明の実施の形態の一例であり、上記のようにして作製した樹脂含浸基材１の１枚の片側に金属箔３を重ねて積層成形することによって、プリント配線板に加工するための金属箔張積層板を製造することができる。つまり、これは片面金属箔張積層板であるが、図１（ａ）に示すように上記の樹脂含浸基材１の１枚の両側に金属箔３を重ねて積層成形することによって、両面金属箔張積層板を製造することもできる。なお、以下で特に区別しない限り、金属箔張積層板とは上記の２種のものを意味するものとする。ここで金属箔３としては、銅箔、アルミニウム箔、ステンレス箔などを用いることができる。このように本発明に係る金属箔張積層板は、１枚の樹脂含浸基材１によって絶縁層２が形成されているため、複数枚の樹脂含浸基材１からなる絶縁層２を有する金属箔張積層板に比べて、樹脂含浸基材１の積層枚数の差だけ厚みを薄くすることができるものである。
【００２０】
そして、図１（ｂ）に示すように、上記のようにして製造される片面金属箔張積層板において、基材４の厚み方向の中心５は絶縁層２の厚み方向の中心６よりも金属箔３側に偏在しているものである。また図１（ａ）に示すように、上記のようにして製造される両面金属箔張積層板においては、基材４の厚み方向の中心５が絶縁層２の厚み方向の中心６よりも一方の金属箔３側に偏在されているものである。ここで、基材４の厚み方向の中心５と、基材４が偏在する側の絶縁層２の表面との距離は、絶縁層２全体の厚みの１／７〜３／７である。また、このときの絶縁層２の厚みは２０〜２００μｍであることが好ましい。絶縁層２の厚みが２０μｍ未満であると、厚み方向の絶縁信頼性が確保し難くなるおそれがある。逆に２００μｍを超えると、小型軽量化を目的とするビルドアップ工法の概念から外れる傾向になるおそれがある。なお、上記で絶縁層２の厚みとは、基材４の厚みとその両面に形成される樹脂層１０の厚みとを合わせたものであり、絶縁層２全体の厚みともいい、下記においても同様である。
【００２１】
そして、本発明に係る金属箔張積層板に非貫通孔７を穿孔するにあたっては、基材４を偏在させた側と反対側の絶縁層２の表面に炭酸ガスレーザＬを照射して絶縁層２に非貫通孔７を形成するものである。すなわち、片面金属箔張積層板に非貫通孔７を穿孔する場合は、図１（ｃ）に示すように金属箔３で被覆されていない絶縁層２の表面に向けて炭酸ガスレーザＬを照射するものであり、他方、図１（ａ）に示すように両面金属箔張積層板に非貫通孔７を穿孔する場合は、基材４を偏在させた側と反対側の絶縁層２の表面を被覆している金属箔３を、予めエッチング等によって除去することによって図１（ｂ）と同様な状態とし、これによって露出された絶縁層２の表面に向けて炭酸ガスレーザＬを照射するものである。
【００２２】
ここで、炭酸ガスレーザＬの照射を開始してから非貫通孔７の底面が形成されるまでの間は、主として炭酸ガスレーザＬの入射光が絶縁層２の除去を行うものであるが、絶縁層２を形成する樹脂と基材４とは異なる素材であるため、入射光だけではこれらを等しく除去することはできず、加工性の悪い基材４が非貫通孔７の内壁面に突出部９として残るものである。しかしながら、炭酸ガスレーザＬの照射を続けると非貫通孔７の底面となる金属箔３が露出され、この金属箔３で炭酸ガスレーザＬが反射されるようになる。このとき本発明に係る金属箔張積層板にあっては、従来のものと比較して基材４が金属箔３側に偏在されているため、上記の基材４の突出部９と非貫通孔７の底面の金属箔３との距離が短くなり、炭酸ガスレーザＬの反射光が基材４の突出部９に照射され易くなるものである。つまり、炭酸ガスレーザＬの入射光に加えて反射光も基材４の突出部９の除去に大きく寄与することができ、図１（ｃ）に示すように基材４の突出部９を非貫通孔７の内壁面から完全に除去することができるようになるものである。従って、穿孔された非貫通孔７の内壁面の全面は滑らかな状態となり、めっき付き回り性が大幅に高められると共に、この非貫通孔７の内壁面に無電解めっき及び電解めっきが施されて形成されるビアホール１１は、優れた導通信頼性を有するものとなるものである。
【００２３】
なお、基材４の厚み方向の中心５が絶縁層２の厚み方向の中心６と一致したり、図５（ａ）に示すように、基材４の厚み方向の中心５が絶縁層２の厚み方向の中心６より金属箔３側と反対側に偏在したりするような金属箔張積層板にあっては、炭酸ガスレーザＬの照射によって非貫通孔７を穿孔しようとしても、図５（ｂ）に示すような状態となって、めっき付き回り性の良い非貫通孔７を得ることは不可能であり、このため導通信頼性の高いビアホール１１を得ることもできないものである。
【００２４】
図３は、本発明に係る金属箔張積層板を用いて多層プリント配線板を製造する工程の一例を示すものであり、金属箔張積層板中の基材４は図示省略している。そしてこの例において、まず本発明に係る金属箔張積層板の両面にサブトラクティブ法などで回路８を形成すると共に、前述したように炭酸ガスレーザＬを必要箇所に照射して非貫通孔７を穿孔し、無電解めっき及び電解めっきを施し、ビアホール１１を形成して両面に形成された回路８間の導通をとる。ここでこのビアホール１１は、多層プリント配線板の製造後においてインナービアホール（ＩｎｔｅｒｓｔｉｔｉａｌＶｉａＨｏｌｅと同義であり、以下ではＩＶＨとする）となるものである。次いで、このようにして得られたものを内層材として、図３（ａ）に示すように、この内層材の両側にエポキシ樹脂等の樹脂からなる樹脂シート１３を配し、積層成形する。その後、図３（ｂ）に示すように、樹脂シート１３の表面に向けて炭酸ガスレーザＬを必要箇所に照射し、非貫通孔７を穿孔するものであるが、一般にこの樹脂シート１３はガラスクロス等の基材４を含まないため、従来法に基づいてめっき付き回り性の良い非貫通孔７を得ることができる。そして、樹脂シート１３で形成された樹脂層１０の表面にアディティブ法などで回路８を形成すると共に、穿孔された非貫通孔７に無電解めっき及び電解めっきを施し、ビアホール１１を形成して内層材に形成された回路８と、樹脂層１０の表面に形成された回路８との間の導通をとることによって、図３（ｃ）に示すような４層を有する多層プリント配線板を得ることができるものである。なお、必要に応じて上記の操作を繰り返すことにより、より多くの層を有する多層プリント配線板を得ることができるものである。
【００２５】
また図４は、本発明に係る金属箔張積層板と従来のものとを併用して多層プリント配線板を製造する工程の一例を示すものであり、金属箔張積層板中の基材４は図示省略している。そしてこの例において、先の例と同様にして回路８及びビアホール１１が形成された金属箔張積層板を用いることができる。一方、複数枚の樹脂含浸基材１からなる従来の金属箔張積層板（図４に示すものは２枚の樹脂含浸基材１からなる）の両面にサブトラクティブ法などで回路８を形成すると共に、貫通孔を穿孔し、無電解めっき及び電解めっきを施し、スルーホール１２を形成して両面に形成された回路８間の導通をとる。そして、図４（ａ）に示すように回路８及びビアホール１１が形成された本発明に係る金属箔張積層板の片側と、回路８及びスルーホール１２が形成された従来の金属箔張積層板の片側とで、エポキシ樹脂等の樹脂からなる樹脂シート１３を挟み込んで積層成形する。このようにして図４（ｂ）に示すような４層を有する多層プリント配線板を得ることができるものである。つまり、この例は、予め複数の金属箔張積層板のそれぞれに回路８及びビアホール１１等を形成しておき、次いでこれらを積層成形して、より多くの層を有する多層プリント配線板を製造するものである。なお、必要に応じて上記の操作や先の例で示した操作を繰り返すことにより、より多くの層を有する多層プリント配線板を得ることもできる。
【００２６】
上記のようにして製造される多層プリント配線板は、金属箔張積層板として１枚の樹脂含浸基材１からなるものを用いているため、複数枚の樹脂含浸基材１からなる従来の金属箔張積層板だけを用いて製造される多層プリント配線板よりも薄いものであり、電気・電子機器の小型化を可能とするものである。つまり、本発明に係る金属箔張積層板を用いることで、従来のものと同一の厚みを有する多層プリント配線板を製造するにあたって、より多くの層を有するものを製造することができる。一方、従来のものと同一の層数を有する多層プリント配線板を製造するにあたって、より薄いものを製造することができるものである。さらに、この多層プリント配線板中のビアホール１１は、めっき付き回り性の良好な非貫通孔７を基にして形成されているため、各層間の導通信頼性は高いものである。
【００２７】
【実施例】
以下、本発明を実施例によって具体的に説明する。
（実施例１）
エポキシ樹脂としてブロム化エポキシ樹脂（東都化成社製「ＹＤＢ−５００」、エポキシ当量５００、臭素含有量２１質量％）を９０質量％、クレゾールノボラック型エポキシ樹脂（大日本インキ化学工業社製「Ｎ−６９０」、エポキシ当量２２５）を１０質量％混合したエポキシ樹脂に、硬化剤としてジシアンジアミドを２．５質量％、硬化促進剤として２−エチル−４−メチルイミダゾールを０．１質量％配合し、さらに溶剤として質量比でメチルエチルケトン：ジメチルホルムアミド＝１：１を混合した液を、上記のエポキシ樹脂組成物の含有率が６０質量％となるように配合し、混合してワニスを得た。
【００２８】
次に上記のワニスを、基材４としてＭＩＬ規格仕様２１１６タイプのガラス基材（旭シュエーベル社製「２１６Ｌ」）に樹脂含有率が樹脂含浸基材１の全量に対して４５質量％となるように含浸し、横型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００２９】
上記の樹脂含浸基材１の１枚の両側に、金属箔３として１８μｍの銅箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、厚み０．１ｍｍの両面銅張積層板を得た。
【００３０】
その後、樹脂含浸基材１乾燥時に下面となった側の銅箔をエッチングした。
（実施例２）
基材４としてＭＩＬ規格仕様１０８０タイプのガラス基材（旭シュエーベル社製「１０８０」）に実施例１と同じワニスを用いて樹脂含有率が樹脂含浸基材１の全量に対して５６質量％となるように含浸し、横型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００３１】
上記の樹脂含浸基材１の１枚の乾燥時に上面となった側に、金属箔３として１８μｍの銅箔を配し、その反対側に離型箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、離型箔を剥がすことにより厚み０．０６ｍｍの片面銅張積層板を得た。
（実施例３）
基材４としてＭＩＬ規格仕様１０６タイプのガラス基材（日東紡績社製「ＷＥＡ１０６」）に実施例１と同じワニスを用いて樹脂含有率が樹脂含浸基材１の全量に対して６５質量％となるように含浸し、横型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００３２】
上記の樹脂含浸基材１の１枚の乾燥時に上面となった側に、金属箔３として１８μｍの銅箔を配し、その反対側に離型箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、離型箔を剥がすことにより厚み０．０４ｍｍの片面銅張積層板を得た。
（実施例４）
樹脂成分として、臭素化３官能型エポキシ樹脂（三井化学社製「ＶＦ−２８０２」、エポキシ当量３７５）をメチルエチルケトンで希釈して固形分濃度７５質量％にしたもの８２ｇと、３官能型エポキシ樹脂（三井化学社製「ＶＧ−３１０１」、エポキシ当量２１０）をメチルエチルケトンで希釈して固形分濃度８０質量％にしたもの２４ｇと臭素化ビスフェノールＡ型エポキシ樹脂（東都化成社製「ＹＤＢ−４００」、エポキシ当量４００）１９ｇとを混合して調製したものを用いた。また硬化剤としてジシアンジアミド２．５ｇ、硬化促進剤として２−エチル−４−メチルイミダゾール０．０６ｇを用いた。そしてこれらをジメチルホルムアミド４３ｇの溶媒に混合することによって、ワニスを得た。
【００３３】
基材４としてＭＩＬ規格仕様１０４タイプのガラス基材（日東紡績社製「ＷＥＡ１０４」）に上記のワニスを用いて樹脂含有率が樹脂含浸基材１の全量に対して６４質量％となるように含浸し、横型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００３４】
上記の樹脂含浸基材１の１枚の乾燥時に上面となった側に、金属箔３として１８μｍの銅箔を配し、その反対側に離型箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、離型箔を剥がすことにより厚み０．０３ｍｍの片面銅張積層板を得た。
（実施例５）
日本ＧＥプラスチック社製の数平均分子量（Ｍｎ）２００００のポリフェニレンエーテル（ＰＰＥ）５０ｇと、スチレンブタジエンコポリマー（旭化成工業社製「タフプレンＡ」）５ｇと、トリアリルイソシアヌレート（ＴＡＩＣ）（日本化成社製）４５ｇと、トルエン１８０ｇとを配合して、９０℃で６０分間撹拌後、反応開始剤として日本油脂社製「パーブチルＰ」を１．５ｇ加えた後、３０℃まで冷却しワニスを得た。
【００３５】
次に上記のワニスを、基材４としてＭＩＬ規格仕様２１１６タイプのガラス基材（旭シュエーベル社製「２１６Ｌ」）に樹脂含有率が樹脂含浸基材１の全量に対して５０質量％となるように含浸し、１３０℃、４分間横型乾燥機で乾燥し、樹脂含浸基材１を作製した。
【００３６】
上記の樹脂含浸基材１の１枚の両側に、金属箔３として１８μｍの銅箔を配して重ね合わせ、次いで温度２１０℃、圧力２．９４ＭＰａで６０分間加熱加圧して厚み０．１ｍｍの両面銅張積層板を得た。
【００３７】
その後、樹脂含浸基材１乾燥時に下面となった側の銅箔をエッチングした。
（実施例６）
基材４としてＭＩＬ規格仕様７６２８タイプのガラス基材（日東紡績社製「ＷＥＡ７６２８」）に実施例４と同じワニスを用いて樹脂含有率が樹脂含浸基材１の全量に対して４５質量％となるように含浸し、横型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００３８】
上記の樹脂含浸基材１の１枚の乾燥時に上面となった側に、金属箔３として１８μｍの銅箔を配し、その反対側に離型箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、離型箔を剥がすことにより厚み０．２ｍｍの片面銅張積層板を得た。
（比較例１）
基材４としてＭＩＬ規格仕様２１１６タイプのガラス基材（旭シュエーベル社製「２１６Ｌ」）に実施例１と同じワニスを用いて樹脂含有率が樹脂含浸基材１の全量に対して４５質量％となるように含浸し、縦型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００３９】
上記の樹脂含浸基材１の１枚の片側に、金属箔３として１８μｍの銅箔を配し、その反対側に離型箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、離型箔を剥がすことにより厚み０．１ｍｍの片面銅張積層板を得た。
（比較例２）
基材４としてＭＩＬ規格仕様１０８０タイプのガラス基材（旭シュエーベル社製「１０８０」）に実施例４と同じワニスを用いて樹脂含有率が樹脂含浸基材１の全量に対して５６質量％となるように含浸し、縦型乾燥機で乾燥し、硬化時間が１７０℃で１５０秒となるように樹脂含浸基材１を作製した。
【００４０】
上記の樹脂含浸基材１の１枚の両側に、金属箔３として１８μｍの銅箔を配した積層体を金属プレート間に挟み、熱盤間に挿入した。樹脂含浸基材１に含浸した樹脂が溶融するまでの間、温度１３０〜１３５℃、初期の加圧を０．９８ＭＰａの低圧で行い、次いで２段目の加圧を２．９４ＭＰａで熱盤温度を１７０℃に上昇させて加熱加圧し、樹脂を完全に硬化させ、厚み０．０６ｍｍの両面銅張積層板を得た。
【００４１】
その後、片側の銅箔をエッチングした。
【００４２】
表１に上記の各実施例及び比較例で用いた基材４のタイプを示すと共に、各基材４の偏在の程度を数値で示す。
【００４３】
【表１】

【００４４】
（めっき付き回り性）
ＩＶＨの形状を比較するため、めっき付き回り性の評価を行った。
【００４５】
まず、実施例及び比較例で得た各銅張積層板に、三菱電機社製炭酸ガスレーザ「ＭＬ６０５ＧＴＸ−５１００Ｕ」を用いて加工を実施し（マスクイメージング加工、バーストモード）、各銅張積層板の表面に非貫通孔７を１０００個穿孔した。なお、炭酸ガスレーザＬは銅箔の無い側に向けて照射した。
【００４６】
次に、この非貫通孔７にセミアディティブ法によってめっき加工を実施した。炭酸ガスレーザＬによって加工した非貫通孔７の内壁面を保持するため、デスミア粗化処理は実施しなかった。めっき加工として、まず給電層としての無電解銅めっきを実施した。ここで、めっき液としては、シプレイ・ファーイースト社製「キューポジット２５３」を標準条件にて使用した。その後、電気銅めっきによって銅皮膜を形成した。ここで、電気銅めっき条件は、非貫通孔７内部へのめっき析出性を考慮して、電流密度を１Ａ／ｄｍ²、めっき時間を８０分とした。
【００４７】
そして、電気銅めっき処理を施して形成された１０００個のＩＶＨうち、１０個をランダムに選び、その断面を観察した。評価は以下の方法で行った。
【００４８】
銅張積層板の表面のめっき厚みを測定した後、ＩＶＨ内の最も薄い部分のめっき厚みを測定し、その厚みが銅張積層板の表面のめっき厚みに対して７０％以上であれば「○」、７０％未満であれば「×」とした。表２に結果を示す。
【００４９】
【表２】

【００５０】
実施例及び比較例を比較すると、実施例の方がめっき付き回り性が良好であることが確認される。
【００５１】
【発明の効果】
上記のように本発明の請求項１に係る金属箔張積層板への非貫通孔の穿孔方法は、樹脂含浸基材によって絶縁層が形成されると共に、絶縁層の表面に金属箔を重ね合わせて積層成形される金属箔張積層板であって、基材の厚み方向の中心が絶縁層の厚み方向の中心より金属箔側に偏在されていると共に、基材の厚み方向の中心と基材が偏在する側の絶縁層の表面との距離が絶縁層全体の厚みの１／７〜３／７であるものに非貫通孔を穿孔するにあたって、上記金属箔張積層板の基材を偏在させた側と反対側の絶縁層の表面に炭酸ガスレーザを照射して絶縁層に非貫通孔を形成するので、炭酸ガスレーザの照射によって非貫通孔の内壁面の全面は滑らかな状態となってめっき付き回り性が向上し、導通信頼性の優れたビアホールを形成することができるものである。
【００５２】
また本発明の請求項２に係る金属箔張積層板への非貫通孔の穿孔方法は、樹脂含浸基材によって絶縁層が形成されると共に、絶縁層の片側表面に金属箔を重ね合わせて積層成形される金属箔張積層板であって、基材の厚み方向の中心が絶縁層の厚み方向の中心より金属箔側に偏在されていると共に、基材の厚み方向の中心と基材が偏在する側の絶縁層の表面との距離が絶縁層全体の厚みの１／７〜３／７であるものに非貫通孔を穿孔するにあたって、上記金属箔張積層板の基材を偏在させた側と反対側の絶縁層の表面に炭酸ガスレーザを照射して絶縁層に非貫通孔を形成するので、炭酸ガスレーザの照射によって非貫通孔の内壁面の全面は滑らかな状態となってめっき付き回り性が向上し、導通信頼性の優れたビアホールを形成することができるものである。
【００５３】
また請求項３の発明は、請求項１において、絶縁層の厚みが２０〜２００μｍであるので、炭酸ガスレーザの照射によって容易にめっき付き回り性の良好な非貫通孔を穿孔することができて、導通信頼性の優れたビアホールを形成することができるものである。
【００５４】
また請求項４の発明は、請求項２において、絶縁層の厚みが２０〜２００μｍであるので、炭酸ガスレーザの照射によって容易にめっき付き回り性の良好な非貫通孔を穿孔することができて、導通信頼性の優れたビアホールを形成することができるものである。
【図面の簡単な説明】
【図１】本発明の実施の形態の一例を示すものであり、（ａ）は両面金属箔張積層板の断面図、（ｂ）は片面金属箔張積層板の断面図、（ｃ）は非貫通孔が穿孔された金属箔張積層板の断面図である。
【図２】本発明に係る金属箔張積層板の製造に用いる樹脂含浸基材を示す断面図である。
【図３】本発明の金属箔張積層板を用いた多層プリント配線板の製造の一例を示すものであり、（ａ）〜（ｃ）はそれぞれ各工程の断面図である。
【図４】本発明の金属箔張積層板を用いた多層プリント配線板の製造の他例を示すものであり、（ａ），（ｂ）はそれぞれ各工程の断面図である。
【図５】従来例を示す断面図である。
【符号の説明】
１樹脂含浸基材
２絶縁層
３金属箔
４基材
５中心
６中心
７非貫通孔
Ｌ炭酸ガスレーザ[0001]
BACKGROUND OF THE INVENTION
In the present invention, carbon dioxide laser irradiation In gold Drill non-through holes in metal foil-clad laminates Who It is about the law.
[0002]
[Prior art]
In the multilayer printed board, the insulating layer 2 is provided between the conductor forming the lower circuit 8 and the conductor forming the upper circuit 8. The insulating layer 2 is formed as follows. That is, first, a resin-impregnated substrate 1 is produced by impregnating a substrate 4 formed of glass such as glass cloth with a resin such as an epoxy resin as a varnish and semi-curing it. Next, the metal foil 3 is overlapped on one surface of the resin-impregnated base material 1 and the other surface is stacked opposite to the lower conductor on which the circuit 8 has been previously formed, and heat-pressing or the like is performed to form a laminate. To do. Thereafter, a conductor for forming the upper circuit 8 is formed by forming the circuit 8 on the metal foil 3 superimposed on the resin-impregnated base material 1. Thus, the insulating layer 2 consists of the resin-impregnated base material 1, and the base material 4 exists in parallel with this in the layer formed with resin.
[0003]
In order to establish conduction between the upper and lower conductors, a part of the insulating layer 2 covering the lower conductor is removed, and a non-through hole 7 in which the conductor is exposed is formed on the bottom surface. The inner wall surface is subjected to electroless plating and electrolytic plating, and a plated layer is provided to form the via hole 11.
[0004]
In drilling the non-through holes 7 as described above, a method using a carbon dioxide laser L is widely used. That is, an opening is formed in advance by sequentially applying an etching resist, exposure, development, etching, etc. to the upper conductor covering the insulating layer 2, and then toward the opening where the surface of the insulating layer 2 is exposed. When the carbon dioxide laser L is irradiated, the non-through hole 7 in which the conductor forming the lower circuit 8 is exposed on the bottom surface can be drilled. Further, the non-through hole 7 having a desired diameter can be drilled by narrowing the beam diameter of the carbon dioxide laser L with an optical system. Then, after drilling, a plating process is performed in the same manner as described above to form the via hole 11, and the upper and lower conductors are made conductive.
[0005]
[Problems to be solved by the invention]
However, when the base 4 4 such as a glass cloth is present as a part of the insulating layer 2 as in the conventional example shown in FIG. 5A, the non-through hole 7 is drilled using the carbon dioxide laser L. As shown in FIG. 5 (b), it is often seen that the base material 4 that has not been completely removed remains as the protruding portion 9 protruding from the inner wall surface of the non-through hole 7. This is because the base material 4 requires more heat energy of the carbon dioxide laser L than the resin in the insulating layer 2 at the time of drilling, but actually the resin and the heat energy received by the base material 4 are much different. This is considered to be because the base material 4 becomes difficult to be processed.
[0006]
If electroless plating or electroplating is performed with the protruding portion 9 left in this way, the plating layer formed on the protruding portion 9 grows faster than those formed at other locations, It was difficult to uniformly provide a plating layer on the inner wall surface by, for example, closing the opening of the through-hole 7, and the ability to attach the plating deteriorated.
[0007]
The present invention has been made in view of the above points, and the non-through hole 7 having good plating revolving property by irradiation with the carbon dioxide gas laser L. The gold Metal foil laminate To wear Punch Who It is intended to provide a law.
[0008]
[Means for Solving the Problems]
A metal foil-clad laminate according to claim 1 of the present invention Method for drilling non-through holes in Is a metal foil-clad laminate in which the insulating layer 2 is formed by the resin-impregnated base material 1 and the surface of the insulating layer 2 is laminated with the metal foil 3 So The center 5 in the thickness direction of the base material 4 is unevenly distributed on the metal foil 3 side from the center 6 in the thickness direction of the insulating layer 2, and the center in the thickness direction of the base material 4 and the side on which the base material 4 is unevenly distributed. The distance from the surface of the insulating layer 2 is 1/7 to 3/7 of the thickness of the entire insulating layer 2 When the non-through hole 7 is drilled in the object, the surface of the insulating layer 2 opposite to the side where the base material 4 of the metal foil-clad laminate is unevenly distributed is irradiated with a carbon dioxide laser L so that the non-through hole is formed in the insulating layer 2. Form 7 It is characterized by this.
[0009]
Also A method for drilling non-through holes in a metal foil-clad laminate according to claim 2 of the present invention Is a metal foil-clad laminate in which the insulating layer 2 is formed by the resin-impregnated base material 1 and the metal foil 3 is laminated and formed on one surface of the insulating layer 2 So The center 5 in the thickness direction of the base material 4 is unevenly distributed on the metal foil 3 side from the center 6 in the thickness direction of the insulating layer 2, and the center in the thickness direction of the base material 4 and the side on which the base material 4 is unevenly distributed. The distance from the surface of the insulating layer 2 is 1/7 to 3/7 of the thickness of the entire insulating layer 2 When the non-through hole 7 is drilled in the object, the surface of the insulating layer 2 opposite to the side where the base material 4 of the metal foil-clad laminate is unevenly distributed is irradiated with a carbon dioxide laser L so that the non-through hole is formed in the insulating layer 2. Form 7 It is characterized by this.
[0010]
The invention of claim 3 is characterized in that, in claim 1, the thickness of the insulating layer 2 is 20 to 200 μm.
[0011]
According to a fourth aspect of the present invention, in the second aspect, the insulating layer 2 has a thickness of 20 to 200 μm.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0014]
In the present invention, the substrate 4 is not particularly limited, and for example, a glass substrate such as a glass cloth, a glass mat, or glass paper can be used.
[0015]
Moreover, it does not specifically limit as resin, For example, an epoxy resin, a phenol resin, a polyimide resin etc. can be used. A varnish can be prepared by mixing a curing agent, a curing accelerator, an additive, and the like with such a resin and diluting with water or an organic solvent as necessary.
[0016]
In producing the resin-impregnated base material 1, the base material 4 is first impregnated with varnish as in the conventional method. The resin content is preferably impregnated so as to be 30 to 80% by mass with respect to the total amount of the resin-impregnated substrate 1. Next, the base material 4 impregnated with the varnish is dried. At this time, the thickness of the resin layer 10 formed on one surface of the base material 4 with the base material 4 as a boundary as shown in FIG. The substrate 4 is dried so as to be thicker than the thickness of the resin layer 10 formed on the other surface, and is in a semi-cured state, and the center 5 of the thickness direction of the substrate 4 is the thickness direction of the resin-impregnated substrate 1. Is unevenly distributed on the one surface side from the center 6 of.
[0017]
Here, in drying the base material 4 impregnated with the varnish as described above, it is preferable to use a horizontal dryer as the dryer. When this horizontal dryer is used, when the uncured resin-impregnated base material 1 is dried by sending it in the horizontal dryer in a substantially horizontal direction, the uncured varnish moves downward as a whole due to gravity. When the substrate is dried in a semi-cured state, the resin-impregnated substrate 1 in which the thickness of the resin layer 10 formed on the lower surface of the substrate 4 is thicker than the thickness of the resin layer 10 formed on the upper surface with the substrate 4 as a boundary. Is produced. The varnish curing conditions such as temperature and time can be appropriately selected.
[0018]
On the other hand, when a vertical dryer is used as the dryer, the vertical dryer dries the uncured resin-impregnated base material 1 while moving it in the substantially vertical direction. It is difficult to change the thickness of the resin layer 10 provided on one surface and the resin layer 10 provided on the other surface, and the thickness of the resin layer 10 provided on both surfaces of the substrate 4 is substantially equal. It is.
[0019]
FIG. 1B is an example of an embodiment of the present invention. A printed wiring is obtained by stacking and forming a metal foil 3 on one side of a resin-impregnated base material 1 produced as described above. A metal foil-clad laminate for processing into a plate can be produced. In other words, this is a single-sided metal foil-clad laminate, but as shown in FIG. 1 (a), the metal foil 3 is laminated on both sides of the above-mentioned resin-impregnated substrate 1 to form a double-sided metal. A foil-clad laminate can also be produced. In addition, unless it distinguishes in particular below, a metal foil tension laminated board shall mean said 2 types of thing. Here, as the metal foil 3, a copper foil, an aluminum foil, a stainless steel foil or the like can be used. As described above, the metal foil-clad laminate according to the present invention has the insulating layer 2 formed by the single resin-impregnated base material 1, and thus has a metal foil having the insulating layer 2 composed of a plurality of resin-impregnated base materials 1. Compared with the tension laminate, the thickness can be reduced by the difference in the number of laminated layers of the resin-impregnated substrate 1.
[0020]
As shown in FIG. 1B, in the single-sided metal foil-clad laminate manufactured as described above, the center 5 in the thickness direction of the substrate 4 is more metal than the center 6 in the thickness direction of the insulating layer 2. It is unevenly distributed on the foil 3 side. Further, as shown in FIG. 1A, in the double-sided metal foil-clad laminate manufactured as described above, the center 5 in the thickness direction of the base material 4 is more than the center 6 in the thickness direction of the insulating layer 2. Are unevenly distributed on the metal foil 3 side. Here, the distance between the center 5 in the thickness direction of the substrate 4 and the surface of the insulating layer 2 on the side where the substrate 4 is unevenly distributed is 1/7 to 3/7 of the thickness of the entire insulating layer 2. The Moreover, it is preferable that the thickness of the insulating layer 2 at this time is 20-200 micrometers. If the thickness of the insulating layer 2 is less than 20 μm, it may be difficult to ensure insulation reliability in the thickness direction. On the other hand, if it exceeds 200 μm, there is a risk of deviating from the concept of the build-up method aimed at reducing the size and weight. In addition, the thickness of the insulating layer 2 is the sum of the thickness of the base material 4 and the thickness of the resin layer 10 formed on both surfaces thereof, and is also referred to as the total thickness of the insulating layer 2. It is.
[0021]
And in punching the non-through-hole 7 in the metal foil tension laminated board which concerns on this invention, the carbon dioxide laser L is irradiated to the surface of the insulating layer 2 on the opposite side to the side where the base material 4 was unevenly distributed, and the insulating layer 2 The non-through-hole 7 is formed in this. That is, when the non-through hole 7 is drilled in the single-sided metal foil-clad laminate, the carbon dioxide laser L is irradiated toward the surface of the insulating layer 2 not covered with the metal foil 3 as shown in FIG. On the other hand, when the non-through hole 7 is drilled in the double-sided metal foil-clad laminate as shown in FIG. 1A, the surface of the insulating layer 2 opposite to the side where the base material 4 is unevenly distributed is formed. The coated metal foil 3 is removed in advance by etching or the like to bring it into a state similar to that shown in FIG. 1B, and the surface of the insulating layer 2 exposed thereby is irradiated with the carbon dioxide laser L. .
[0022]
Here, during the period from the start of irradiation with the carbon dioxide laser L until the bottom surface of the non-through hole 7 is formed, the incident light of the carbon dioxide laser L mainly removes the insulating layer 2. 2 and the base material 4 are different materials. Therefore, the incident light alone cannot remove them equally, and the base material 4 having poor processability is projected on the inner wall surface of the non-through hole 7. It remains as. However, when the irradiation of the carbon dioxide laser L is continued, the metal foil 3 that becomes the bottom surface of the non-through hole 7 is exposed, and the carbon dioxide laser L is reflected by the metal foil 3. At this time, in the metal foil-clad laminate according to the present invention, since the base material 4 is unevenly distributed on the metal foil 3 side as compared with the conventional one, the protruding portion 9 of the base material 4 is not penetrated. The distance between the bottom surface of the hole 7 and the metal foil 3 is shortened, and the reflected light of the carbon dioxide laser L is easily irradiated to the protruding portion 9 of the substrate 4. That is, in addition to the incident light of the carbon dioxide laser L, the reflected light can greatly contribute to the removal of the protruding portion 9 of the base material 4 and does not penetrate the protruding portion 9 of the base material 4 as shown in FIG. It can be completely removed from the inner wall surface of the hole 7. Accordingly, the entire inner wall surface of the perforated non-through hole 7 becomes smooth, and the recirculation with plating is greatly enhanced, and the inner wall surface of the non-through hole 7 is subjected to electroless plating and electrolytic plating. The via hole 11 to be formed has excellent conduction reliability.
[0023]
In addition, the center 5 in the thickness direction of the base material 4 coincides with the center 6 in the thickness direction of the insulating layer 2, or the center 5 in the thickness direction of the base material 4 is the insulating layer 2 as shown in FIG. In the case of a metal foil-clad laminate that is unevenly distributed from the center 6 in the thickness direction to the side opposite to the metal foil 3 side, even if an attempt is made to perforate the non-through hole 7 by irradiation with the carbon dioxide laser L, FIG. ), It is impossible to obtain the non-through hole 7 with good plating revolving property, and therefore, it is impossible to obtain the via hole 11 having high conduction reliability.
[0024]
FIG. 3 shows an example of a process for producing a multilayer printed wiring board using the metal foil-clad laminate according to the present invention, and the substrate 4 in the metal foil-clad laminate is not shown. In this example, first, the circuit 8 is formed on both surfaces of the metal foil-clad laminate according to the present invention by a subtractive method or the like, and the non-through holes 7 are drilled by irradiating the carbon dioxide laser L to the necessary portions as described above. Then, electroless plating and electrolytic plating are performed to form a via hole 11 to establish conduction between the circuits 8 formed on both surfaces. Here, the via hole 11 becomes an inner via hole (synonymous with Interstitial Via Hole, hereinafter referred to as IVH) after the production of the multilayer printed wiring board. Next, using the thus obtained inner layer material, as shown in FIG. 3A, resin sheets 13 made of a resin such as an epoxy resin are arranged on both sides of the inner layer material, and laminated. Thereafter, as shown in FIG. 3 (b), a carbon dioxide laser L is irradiated to a required portion toward the surface of the resin sheet 13 to perforate the non-through holes 7. In general, the resin sheet 13 is made of glass cloth. Therefore, the non-through-hole 7 having good plating ability can be obtained based on the conventional method. Then, the circuit 8 is formed on the surface of the resin layer 10 formed of the resin sheet 13 by an additive method or the like, and electroless plating and electrolytic plating are performed on the perforated non-through holes 7 to form via holes 11 to form inner layers. By obtaining conduction between the circuit 8 formed on the material and the circuit 8 formed on the surface of the resin layer 10, a multilayer printed wiring board having four layers as shown in FIG. 3C is obtained. Is something that can be done. In addition, a multilayer printed wiring board having more layers can be obtained by repeating the above operation as necessary.
[0025]
FIG. 4 shows an example of a process for producing a multilayer printed wiring board by using a metal foil-clad laminate according to the present invention and a conventional one, and the substrate 4 in the metal foil-clad laminate is The illustration is omitted. In this example, a metal foil-clad laminate in which the circuit 8 and the via hole 11 are formed can be used as in the previous example. On the other hand, a circuit 8 is formed on both surfaces of a conventional metal foil-clad laminate composed of a plurality of resin-impregnated substrates 1 (the one shown in FIG. 4 is composed of two resin-impregnated substrates 1) by a subtractive method or the like. At the same time, through-holes are drilled, electroless plating and electrolytic plating are performed, through-holes 12 are formed, and conduction between the circuits 8 formed on both surfaces is established. 4A, one side of the metal foil-clad laminate according to the present invention in which the circuit 8 and the via hole 11 are formed, and the conventional metal foil-clad laminate in which the circuit 8 and the through hole 12 are formed. The resin sheet 13 made of a resin such as an epoxy resin is sandwiched between one side and the other side of the sheet and laminated. In this manner, a multilayer printed wiring board having four layers as shown in FIG. 4B can be obtained. That is, in this example, a circuit 8 and a via hole 11 are formed in advance on each of a plurality of metal foil-clad laminates, and then these are laminated to produce a multilayer printed wiring board having more layers. Is. In addition, the multilayer printed wiring board which has more layers can also be obtained by repeating said operation and the operation shown in the previous example as needed.
[0026]
The multilayer printed wiring board manufactured as described above uses a metal foil-clad laminate made of a single resin-impregnated base material 1, and thus a conventional metal made of a plurality of resin-impregnated base materials 1 It is thinner than a multilayer printed wiring board manufactured using only a foil-clad laminate, and enables downsizing of electric / electronic devices. That is, by using the metal foil-clad laminate according to the present invention, it is possible to manufacture a multi-layer printed wiring board having the same thickness as that of a conventional one having more layers. On the other hand, when manufacturing a multilayer printed wiring board having the same number of layers as a conventional one, a thinner one can be manufactured. Further, since the via hole 11 in the multilayer printed wiring board is formed based on the non-through hole 7 having good plating revolving property, the conduction reliability between the layers is high.
[0027]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
(Example 1)
As epoxy resin, brominated epoxy resin (“YDB-500” manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 500, bromine content 21% by mass) is 90% by mass, cresol novolac type epoxy resin (manufactured by Dainippon Ink & Chemicals, Inc. “N- 690 ", epoxy equivalent 225) mixed with 10% by mass of epoxy resin, 2.5% by mass of dicyandiamide as a curing agent, 0.1% by mass of 2-ethyl-4-methylimidazole as a curing accelerator, A liquid in which methyl ethyl ketone: dimethylformamide = 1: 1 was mixed as a solvent in a mass ratio was blended so that the content of the epoxy resin composition was 60% by mass and mixed to obtain a varnish.
[0028]
Next, the above-mentioned varnish is used as the base material 4 in a MIL standard specification 2116 type glass base material (“216L” manufactured by Asahi Sebel) so that the resin content is 45% by mass with respect to the total amount of the resin-impregnated base material 1. The resin-impregnated substrate 1 was prepared so that the curing time was 150 ° C. and 150 seconds.
[0029]
A laminate in which 18 μm copper foil was disposed as the metal foil 3 on both sides of one of the resin-impregnated base materials 1 was sandwiched between metal plates and inserted between hot plates. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a heat plate temperature of 2.94 MPa. Was raised to 170 ° C. and heated and pressed to completely cure the resin, and a double-sided copper clad laminate having a thickness of 0.1 mm was obtained.
[0030]
Thereafter, the copper foil on the side that became the lower surface when the resin-impregnated substrate 1 was dried was etched.
(Example 2)
The same varnish as in Example 1 was used for a glass substrate of MIL standard specification 1080 type (“1080” manufactured by Asahi Schavel Co.) as the substrate 4, and the resin content was 56% by mass with respect to the total amount of the resin-impregnated substrate 1. The resin-impregnated base material 1 was prepared so that the curing time was 150 ° C. for 150 seconds.
[0031]
On the side of the above resin-impregnated base material 1 which is the top surface when dried, a laminate of 18 μm copper foil as metal foil 3 and release foil on the opposite side is sandwiched between metal plates. , Inserted between hot plates. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a hot plate temperature of 2.94 MPa. Was raised to 170 ° C., heated and pressurized, the resin was completely cured, and the release foil was peeled off to obtain a single-sided copper-clad laminate having a thickness of 0.06 mm.
(Example 3)
The same varnish as in Example 1 was used for the MIL standard specification 106 type glass substrate ("WEA 106" manufactured by Nitto Boseki Co., Ltd.) as the substrate 4, and the resin content was 65% by mass with respect to the total amount of the resin-impregnated substrate 1. The resin-impregnated base material 1 was prepared so that the curing time was 150 ° C. for 150 seconds.
[0032]
On the side of the above resin-impregnated base material 1 which is the top surface when dried, a laminate of 18 μm copper foil as metal foil 3 and release foil on the opposite side is sandwiched between metal plates. , Inserted between hot plates. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a heat plate temperature of 2.94 MPa. Was raised to 170 ° C., heated and pressed to completely cure the resin, and the release foil was peeled off to obtain a single-sided copper-clad laminate having a thickness of 0.04 mm.
Example 4
As a resin component, 82 g of a brominated trifunctional epoxy resin (“VF-2802” manufactured by Mitsui Chemicals, Inc., epoxy equivalent 375) diluted with methyl ethyl ketone to a solid content concentration of 75% by mass, and a trifunctional epoxy resin ( 24g of Mitsui Chemicals'"VG-3101", epoxy equivalent 210) diluted with methyl ethyl ketone to a solid content concentration of 80% by mass and brominated bisphenol A type epoxy resin ("YDB-400" manufactured by Toto Kasei Co., Ltd.), epoxy (Equivalent 400) prepared by mixing 19 g was used. Further, 2.5 g of dicyandiamide was used as a curing agent, and 0.06 g of 2-ethyl-4-methylimidazole was used as a curing accelerator. And varnish was obtained by mixing these with the solvent of 43 g of dimethylformamide.
[0033]
Using the above varnish for the MIL standard specification 104 type glass substrate (“WEA104” manufactured by Nitto Boseki Co., Ltd.) as the substrate 4, the resin content is 64 mass% with respect to the total amount of the resin-impregnated substrate 1. The resin-impregnated base material 1 was prepared so as to be impregnated and dried by a horizontal drier so that the curing time was 150 seconds at 170 ° C.
[0034]
On the side of the above resin-impregnated base material 1 which is the top surface when dried, a laminate of 18 μm copper foil as metal foil 3 and release foil on the opposite side is sandwiched between metal plates. , Inserted between hot plates. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a heat plate temperature of 2.94 MPa. Was raised to 170 ° C., heated and pressed to completely cure the resin, and the release foil was peeled off to obtain a single-sided copper-clad laminate having a thickness of 0.03 mm.
(Example 5)
50 g of polyphenylene ether (PPE) having a number average molecular weight (Mn) of 20000 made by GE Plastics, 5 g of styrene butadiene copolymer (“Tufprene A” manufactured by Asahi Kasei Kogyo Co., Ltd.), triallyl isocyanurate (TAIC) (manufactured by Nippon Kasei Co., Ltd.) ) 45 g and 180 g of toluene were blended and stirred at 90 ° C. for 60 minutes, and then 1.5 g of “Perbutyl P” manufactured by NOF Corporation was added as a reaction initiator, and then cooled to 30 ° C. to obtain a varnish.
[0035]
Next, the above-mentioned varnish is used as the base material 4 in a MIL standard specification 2116 type glass base material ("216L" manufactured by Asahi Schwer) so that the resin content becomes 50% by mass with respect to the total amount of the resin-impregnated base material 1. And dried with a horizontal dryer at 130 ° C. for 4 minutes to prepare a resin-impregnated substrate 1.
[0036]
An 18 μm copper foil as metal foil 3 is placed on both sides of one of the resin-impregnated base materials 1 and superimposed, and then heated and pressed at a temperature of 210 ° C. and a pressure of 2.94 MPa for 60 minutes to have a thickness of 0.1 mm. A double-sided copper-clad laminate was obtained.
[0037]
Thereafter, the copper foil on the side that became the lower surface when the resin-impregnated substrate 1 was dried was etched.
(Example 6)
The same varnish as in Example 4 was used for the MIL standard specification 7628 type glass substrate (“WEA 7628” manufactured by Nitto Boseki Co., Ltd.) as the substrate 4, and the resin content was 45% by mass with respect to the total amount of the resin-impregnated substrate 1. The resin-impregnated base material 1 was prepared so that the curing time was 150 ° C. for 150 seconds.
[0038]
On the side of the above resin-impregnated base material 1 which is the top surface when dried, a laminate of 18 μm copper foil as metal foil 3 and release foil on the opposite side is sandwiched between metal plates. , Inserted between hot plates. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a heat plate temperature of 2.94 MPa. Was raised to 170 ° C., heated and pressed to completely cure the resin, and the release foil was peeled off to obtain a single-sided copper-clad laminate having a thickness of 0.2 mm.
(Comparative Example 1)
The same varnish as in Example 1 was used for the MIL standard specification 2116 type glass base material ("216L" manufactured by Asahi Schwer) as the base material 4, and the resin content was 45% by mass with respect to the total amount of the resin-impregnated base material 1. The resin-impregnated substrate 1 was prepared so that the curing time was 150 ° C. for 150 seconds.
[0039]
A laminated body in which 18 μm copper foil is arranged as the metal foil 3 on one side of the resin impregnated substrate 1 and the release foil is arranged on the opposite side is sandwiched between metal plates and inserted between hot plates. did. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a heat plate temperature of 2.94 MPa. Was raised to 170 ° C., heated and pressed to completely cure the resin, and the release foil was peeled off to obtain a single-sided copper-clad laminate having a thickness of 0.1 mm.
(Comparative Example 2)
The same varnish as in Example 4 was used for the MIL standard specification 1080 type glass base material (“1080” manufactured by Asahi Schwer) as the base material 4, and the resin content was 56% by mass with respect to the total amount of the resin-impregnated base material 1. The resin-impregnated substrate 1 was prepared so that the curing time was 150 ° C. for 150 seconds.
[0040]
A laminate in which 18 μm copper foil as metal foil 3 was disposed on both sides of one of the resin-impregnated base materials 1 was sandwiched between metal plates and inserted between hot plates. Until the resin impregnated in the resin-impregnated base material 1 is melted, the temperature is 130 to 135 ° C., the initial pressurization is performed at a low pressure of 0.98 MPa, and then the second pressurization is performed at a hot plate temperature of 2.94 MPa. Was raised to 170 ° C. and heated and pressed to completely cure the resin, and a double-sided copper clad laminate having a thickness of 0.06 mm was obtained.
[0041]
Thereafter, the copper foil on one side was etched.
[0042]
Table 1 shows the types of the base materials 4 used in each of the above examples and comparative examples, and also shows the degree of uneven distribution of the base materials 4 by numerical values.
[0043]
[Table 1]

[0044]
(Circularity with plating)
In order to compare the shape of IVH, the revolving property with plating was evaluated.
[0045]
First, each copper-clad laminate obtained in the examples and comparative examples was processed using a carbon dioxide laser “ML605GTX-5100U” manufactured by Mitsubishi Electric Corporation (mask imaging processing, burst mode). 1000 non-through holes 7 were drilled on the surface. The carbon dioxide laser L was irradiated toward the side without the copper foil.
[0046]
Next, the non-through hole 7 was plated by a semi-additive method. In order to hold the inner wall surface of the non-through hole 7 processed by the carbon dioxide laser L, the desmear roughening treatment was not performed. As the plating process, first, electroless copper plating as a power feeding layer was performed. Here, “Cuposit 253” manufactured by Shipley Far East Co., Ltd. was used as a plating solution under standard conditions. Thereafter, a copper film was formed by electrolytic copper plating. Here, the electrolytic copper plating conditions are set such that the current density is 1 A / dm in consideration of the plating depositability inside the non-through hole 7. ² The plating time was 80 minutes.
[0047]
And 10 pieces were chosen at random among 1000 IVHs formed by performing the electrolytic copper plating treatment, and the cross section was observed. Evaluation was performed by the following method.
[0048]
After measuring the plating thickness on the surface of the copper-clad laminate, the plating thickness of the thinnest part in the IVH is measured, and if the thickness is 70% or more with respect to the plating thickness on the surface of the copper-clad laminate, “○ ", If less than 70%," x ". Table 2 shows the results.
[0049]
[Table 2]

[0050]
Comparing the example and the comparative example, it is confirmed that the example has better plating revolving property.
[0051]
【The invention's effect】
As described above, the metal foil-clad laminate according to claim 1 of the present invention. Method for drilling non-through holes in Is a metal foil-clad laminate in which an insulating layer is formed by a resin-impregnated base material and a metal foil is laminated and molded on the surface of the insulating layer So The center in the thickness direction of the base material is unevenly distributed on the metal foil side from the center in the thickness direction of the insulating layer, and the distance between the center in the thickness direction of the base material and the surface of the insulating layer on the side where the base material is unevenly distributed Is 1/7 to 3/7 of the thickness of the entire insulating layer When a non-through hole is drilled in an object, a non-through hole is formed in the insulating layer by irradiating the surface of the insulating layer opposite to the side where the base material of the metal foil-clad laminate is unevenly distributed with a carbon dioxide laser. So by the irradiation of carbon dioxide laser The entire inner wall surface of the non-through hole is in a smooth state to improve the plating coverage, A via hole having excellent conduction reliability can be formed.
[0052]
Also A method for drilling non-through holes in a metal foil-clad laminate according to claim 2 of the present invention Is a metal foil-clad laminate in which an insulating layer is formed by a resin-impregnated base material, and a metal foil is laminated on one surface of the insulating layer and laminated. So The center in the thickness direction of the base material is unevenly distributed on the metal foil side from the center in the thickness direction of the insulating layer, and the distance between the center in the thickness direction of the base material and the surface of the insulating layer on the side where the base material is unevenly distributed Is 1/7 to 3/7 of the thickness of the entire insulating layer When a non-through hole is drilled in an object, a non-through hole is formed in the insulating layer by irradiating the surface of the insulating layer opposite to the side where the base material of the metal foil-clad laminate is unevenly distributed with a carbon dioxide laser. So by the irradiation of carbon dioxide laser The entire inner wall surface of the non-through hole is in a smooth state to improve the plating coverage, A via hole having excellent conduction reliability can be formed.
[0053]
Moreover, since the thickness of the insulating layer is 20 to 200 μm in claim 1, the invention of claim 3 can easily perforate non-through holes with good plating rotability by irradiation with a carbon dioxide laser, A via hole having excellent conduction reliability can be formed.
[0054]
Moreover, since the thickness of an insulating layer is 20-200 micrometers in invention of Claim 4, since the thickness of an insulating layer is 20-200 micrometers, it can pierce | pierce the non-through-hole with favorable plating rotation property easily by irradiation of a carbon dioxide gas laser, A via hole having excellent conduction reliability can be formed.
[Brief description of the drawings]
FIG. 1 shows an example of an embodiment of the present invention, where (a) is a cross-sectional view of a double-sided metal foil-clad laminate, (b) is a cross-sectional view of a single-sided metal foil-clad laminate, and (c) is a cross-sectional view. It is sectional drawing of the metal foil tension laminated board by which the non-through-hole was pierced.
FIG. 2 is a cross-sectional view showing a resin-impregnated base material used for producing a metal foil-clad laminate according to the present invention.
FIG. 3 shows an example of the production of a multilayer printed wiring board using the metal foil-clad laminate of the present invention, and (a) to (c) are sectional views of the respective steps.
FIGS. 4A and 4B show another example of manufacturing a multilayer printed wiring board using the metal foil-clad laminate of the present invention, and FIGS. 4A and 4B are cross-sectional views of the respective steps.
FIG. 5 is a cross-sectional view showing a conventional example.
[Explanation of symbols]
1 Resin impregnated substrate
2 Insulating layer
3 Metal foil
4 Base material
5 center
6 center
7 Non-through hole
L Carbon dioxide laser

Claims

A metal foil-clad laminate in which an insulating layer is formed by a resin-impregnated base material and a metal foil is laminated on the surface of the insulating layer, and the center in the thickness direction of the base material is the thickness direction of the insulating layer The distance between the center in the thickness direction of the base material and the surface of the insulating layer on the side where the base material is uneven is 1/7 to 3/7 of the thickness of the entire insulating layer. When drilling non-through holes in a certain object, the surface of the insulating layer opposite to the side on which the base material of the metal foil-clad laminate is unevenly distributed is irradiated with a carbon dioxide laser to form non-through holes in the insulating layer. A method of drilling non-through holes in a metal foil-clad laminate characterized by the above.

A metal foil-clad laminate in which an insulating layer is formed by a resin-impregnated base material and a metal foil is laminated on one surface of the insulating layer, and the center of the base material in the thickness direction is the thickness of the insulating layer The distance between the center in the thickness direction of the base material and the surface of the insulating layer on the side where the base material is uneven is 1/7 to 3/7 of the thickness of the entire insulating layer. When a non-through hole is drilled in the above, the surface of the insulating layer opposite to the side where the base material of the metal foil-clad laminate is unevenly distributed is irradiated with a carbon dioxide laser to form a non-through hole in the insulating layer. A method for drilling non-through holes in a metal foil-clad laminate.

The thickness of an insulating layer is 20-200 micrometers, The drilling method of the non-through-hole to the metal foil tension laminated board of Claim 1 characterized by the above-mentioned.

The thickness of an insulating layer is 20-200 micrometers, The punching method of the non-through-hole to the metal foil tension laminated board of Claim 2 characterized by the above-mentioned.