JP4023152B2

JP4023152B2 - Manufacturing method of multilayer printed wiring board

Info

Publication number: JP4023152B2
Application number: JP2001392105A
Authority: JP
Inventors: 一信盛岡
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2001-12-25
Filing date: 2001-12-25
Publication date: 2007-12-19
Anticipated expiration: 2021-12-25
Also published as: JP2003198124A

Description

【０００１】
【発明の属する技術分野】
本発明は、複数枚の回路板をプリプレグを介して積層成形することによって行なわれる多層プリント配線板の製造方法に関するものである。
【０００２】
【従来の技術】
多層プリント配線板を製造するにあたっては、例えば図５に示すようにして行なわれている。すなわち、表面に回路形成をした内層用の回路板１を複数枚用い、図５（ａ）のように隣合う回路板１間にプリプレグ２を挟んで複数枚の回路板１を重ね、さらに必要に応じて外側にプリプレグ２を介して外層回路形成用の金属箔１０を重ね、そしてこれを加熱加圧成形することによって、プリプレグ２の樹脂が溶融硬化して形成される絶縁接着層３で複数枚の回路板１や金属箔１０を積層一体化した図５（ｂ）のような多層プリント配線板を得ることができるものである。
【０００３】
上記のようにして作製される多層プリント配線板において、複数枚の回路板１によって複数層の回路が形成されており、これらの各回路はスルーホールやバイヤホール等で導通接続されるようになっている。従って、加熱加圧成形の際に複数枚の各回路板１が相互に位置ずれすることを防止して、それぞれの回路が相互に正確に位置合わせされた状態で積層する必要がある。
【０００４】
そこで、ハトメピン６などを用い、図５（ａ）に鎖線で示すようにハトメピン６を回路板１やプリプレグ２の端部に貫通させてかしめることによって、複数枚の回路板１を相互に固定し、この状態で加熱加圧成形を行なうようにしている。ハトメピン６などを用いて結合する結合部４は、図６に示すように回路板１の四隅の部分に設定するのが一般的である。そしてこのように複数枚の回路板１を相互に固定した状態で加熱加圧成形を行なうことによって、回路板１が相互に位置ずれすることを防止し、各回路板１の回路が正確に位置合わせされた多層プリント配線板を得ることができるのである。
【０００５】
【発明が解決しようとする課題】
多層プリント配線板の製造に用いられる上記の回路板１は、ガラスクロスなどに熱硬化性樹脂ワニスを含浸・乾燥して調製したプリプレグを複数枚重ねると共にその外側に銅箔等の金属箔を重ね、これを加熱加圧成形して金属箔張り積層板を作製し、この金属箔張り積層板の金属箔にエッチング加工を施して回路形成をすることによって、製造されている。そしてこの回路板１を複数枚用いて上記のように加熱加圧成形して多層に成形する場合、加熱加圧成形をした後の回路板１には寸法収縮が生じる。
【０００６】
ここで、回路板１の基材であるガラスクロスはタテ方向とヨコ方向の織り込み本数が異なるので、回路板１が加熱加圧によって寸法収縮する場合、回路板１はこのタテ方向とヨコ方向で収縮率が異なる。また回路板１に形成される回路のパターンによってもタテ方向とヨコ方向で収縮率が異なる。従って、正方形乃至長方形に形成される回路板１の対向する二辺間の方向での収縮率と、これと直交する他の対向する二辺間の方向での収縮率とは異なるので、積層される複数枚の各回路板１はその方向によって収縮率が相互に異なるのが一般的である。そして積層される複数枚の回路板１はその厚みや層構成によって収縮率が大きく異なる。このために、積層される回路板１間において収縮率の差が大きい方向では、収縮率の差が０．０５％以上になることが多い。
【０００７】
しかしこのように隣合って積層される回路板１の収縮率の差が大きいと、上記のように四隅をハトメピン６などの結合部４で固定した状態で加熱加圧成形を行なっても、収縮率の差の大きい方向で隣合う回路板１が位置ずれすることを抑制することができず、各回路板１に形成した回路が層間位置ずれするおそれがあるという問題が発生するものであった。
【０００８】
本発明は上記の点に鑑みてなされたものであり、回路板の位置ずれを防止して、回路が層間位置ずれすることを防ぐことができる多層プリント配線板の製造方法を提供することを目的とするものである。
【０００９】
【課題を解決するための手段】
本発明の請求項１に係る多層プリント配線板の製造方法は、回路形成した回路板１を、少なくとも隣合う回路板１間にプリプレグ２を介して重ね、これを加熱加圧成形することによって、プリプレグ２による絶縁接着層３を介して複数枚の回路板１を積層一体化して多層プリント配線板を製造するにあたって、隣合う回路板１において加熱加圧成形によって回路板１に発生する収縮率の差が大きい方向での両端の辺縁を結合させ、この状態で加熱加圧成形を行なうことを特徴とするものである。
【００１０】
また請求項２の発明は、請求項１において、隣合う回路板１の収縮率の差が０．０５％大きくなる毎に、隣合う回路板１の辺縁を結合させる結合部４の総面積を２倍以上にすることを特徴とするものである。
【００１１】
また請求項３の発明は、請求項１において、隣合う回路板１の収縮率の差が０．０５％大きくなる毎に、隣合う回路板１の辺縁を結合させる結合部４の数を１．５倍以上にすることを特徴とするものである。
【００１２】
また請求項４の発明は、請求項１乃至３のいずれかにおいて、隣合う回路板１の辺縁を結合するにあたって、プリプレグ２の樹脂を部分的に回路板１に熱溶着させることによって行なうことを特徴とするものである。
【００１３】
また請求項５の発明は、請求項４において、回路板１に熱溶着させた部分の樹脂の溶融開始温度がプリプレグ２の他の部分の樹脂のガラス転移点よりも高くなるように、プリプレグ２の熱溶着させた部分の樹脂の硬化度を設定することを特徴とするものである。
【００１４】
また請求項６の発明は、請求項４又は５において、隣合う回路板１の収縮率の差が０．０５％以上であるとき、回路板１に熱溶着させた部分の樹脂の溶融開始温度が１３０℃以上になるように、プリプレグ２の熱溶着させた部分の樹脂の硬化度を設定することを特徴とするものである。
【００１５】
また請求項７の発明は、請求項１乃至３のいずれかにおいて、隣合う回路板１の辺縁を結合するにあたって、回路板１及びプリプレグ２の辺縁に設けた孔５にハトメピン６を通してかしめることによって行なうことを特徴とするものである。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
【００１７】
本発明において回路板１としては、内層用回路板などとして用いられている任意のものを使用することができるものである。すなわち、ガラスクロスなどの基材にエポキシ樹脂などの熱硬化性樹脂ワニスを含浸して加熱乾燥することによってプリプレグを作製し、このプリプレグを複数枚重ねると共にその外側に銅箔など金属箔を重ね、これを加熱加圧成形することによって金属箔張り積層板を作製し、そしてこの金属箔張り積層板の金属箔をエッチング加工などして回路形成をすることによって製造されたものを用いることができる。
【００１８】
またプリプレグ２としては、多層成形用などとして用いられている任意のものを使用することができるものである。すなわち、ガラスクロスなどの基材にエポキシ樹脂などの熱硬化性樹脂ワニスを含浸し、これを加熱乾燥して含浸した熱硬化性樹脂を半硬化状態にすることによって、製造されたものを用いることができる。
【００１９】
上記の複数枚の回路板１を内層材として用い、複数枚の回路板１をプリプレグ２を介して加熱加圧成形して積層一体化することによって、多層プリント配線板を製造することができるものであるが、この成形をするに先だって、回路板１の収縮率を測定しておく。回路板１の収縮率の測定は、多層プリント配線板を製造する際の成形条件と同じ条件で回路板１を加熱加圧成形し、加熱加圧成形する前の寸法と加熱加圧した後の寸法を計測することによって行なうことができるものであり、この寸法の差から収縮率を求めることができる。この収縮率の測定は、正方形乃至長方形に形成される回路板１の対向する二辺間の方向と、他の対向する二辺間の方向の、直交する二方向でそれぞれ行なわれるものである。勿論、収縮率の測定はサンプルとして抽出した回路板１についてのみ行なえばよい。
【００２０】
そして、複数枚（図の実施の形態では二枚）の回路板１を、隣合う回路板１間に一枚乃至複数枚のプリプレグ２を挟んで重ねるにあたって、回路板１が相互に位置ずれしないように結合する。この結合は、例えば、二枚の回路板１間にプリプレグ２を挟んだ状態で、両側の回路板１の外面に溶着へッドなどをスポット状に押し当て、加圧しながら加熱することによって、プリプレグ２に含浸されている半硬化状態の樹脂を溶融・固化させて各回路板１の内面に熱溶着させることによって行なうことができるものであり、この回路板１に溶着するプリプレグ２の溶着樹脂４ａが結合部４となって回路板１を結合することができるものである。
【００２１】
ここで本発明では、プリプレグ２を介して重ねる二枚の回路板１において、同じ対向する二辺間の方向（図１（ｂ）のイ矢印方向）での収縮率の差と、これと直交する他の対向する二辺間の方向（図１（ｂ）のロ矢印方向）での収縮率の差を求め、収縮率の差が大きいほうの方向（例えば図１（ｂ）のイ矢印方向）における両端の二辺の各辺縁に沿って、図１（ｂ）や図２（ａ）（ｂ）に示すように少なくとも３箇所の複数箇所で結合を行なうようにするものである。
【００２２】
次に、このようにプリプレグ２を挟んで重ねると共に結合部４によって結合した複数枚の回路板１の外側に、必要に応じて図１（ａ）のように一枚乃至複数枚のプリプレグ２及び銅箔等の金属箔１０を重ね、これを加熱加圧成形することによって、図１（ｃ）のような、プリプレグ２の含浸樹脂が溶融硬化して形成される絶縁接着層３で複数枚の回路板１及び外層回路用の金属箔１０を積層一体化した多層プリント配線板を製造することができるものである。このように加熱加圧成形を行なうにあたって、複数の回路板１は結合部４で相互に結合しているので、成形の際に相互にずれ動くことを防ぐことができる。また加熱加圧成形によって各回路板１は寸法収縮するが、収縮率の差が大きいほうの方向における両端の二辺の各辺縁に沿って各回路板１を結合しているので、この方向で各回路板１が寸法収縮によって相互に変位することを規制することができ、収縮率の差からこの方向に回路板１が相互に位置ずれすることを抑制することができるものである。従って、各回路板１の位置ずれを防止して、各回路板１の回路が正確に位置合わせされた多層プリント配線板を得ることができるものである。
【００２３】
ここで、上記のように収縮率の差が大きいほうの方向における両端の二辺の各辺縁に沿って隣合う回路板１を結合部４で結合するにあたって、回路板１間の収縮率の差が大きくなると各回路板１の寸法収縮による変位の差が大きくなるので、結合の強度を高くしないと、各回路板１が相互に変位して位置ずれすることを抑制することが難しくなる。
【００２４】
従って本発明では、各回路板１間の収縮率の差が大きくなるにつれて、二辺の各辺縁に沿って設けられる結合部４の各辺縁での総面積を大きくし、結合部４による回路板１間の結合の強度を高めるようにするのが好ましい。具体的には、回路板１の収縮率の差が０．０５％大きくなる毎に、回路板１の各辺縁を結合させる結合部４の総面積を２倍以上にするのが好ましい。例えば、収縮率の差が０．０５％のときに回路板１の位置ずれが発生しない結合部４の総面積を実験的に求めておき、収縮率の差が０．１％のときにはその総面積の２倍以上の面積で結合部４を形成するものである。
【００２５】
さらに、各回路板１間の収縮率の差が大きくなるにつれて、二辺の各辺縁に沿って設けられる結合部４の箇所の数を多くし、結合部４による回路板１間の結合の強度を高めるようにすることもできる。具体的には、回路板１の収縮率の差が０．０５％大きくなる毎に、回路板１の各辺縁を結合させる結合部４の数を１．５倍以上にするのが好ましい。例えば、収縮率の差が０．０５％のときに回路板１の位置ずれが発生しない結合部４の数を実験的に求めておき、収縮率の差が０．１％のときにはその数の１．５倍以上の個数で結合部４を形成するものである。
【００２６】
また、上記のようにプリプレグ２の樹脂を部分的に回路板１に熱溶着させることによって回路板１の結合を行なう場合、結合部４の溶着樹脂４ａは樹脂硬化度が高いほうが結合強度が高くなる。すなわち、樹脂硬化度が高いと溶融開始温度が高くなるので、多層プリント配線板を製造するときの加熱加圧成形の際に樹脂硬化度が高い結合部４の溶着樹脂４ａは溶融し難くなり、溶着樹脂４ａによる回路板１間の結合強度を高く得ることができるものである。結合部４の溶着樹脂４ａの樹脂硬化度の調整は、二枚の回路板１間にプリプレグ２を挟んだ状態で回路板１の外面に溶着へッドなどを押し当てて加熱加圧し、熱溶着を行なう際に、加熱温度や加熱時間を制御して、溶着樹脂４ａの架橋密度を調整することによって行なうことができる。具体的には、プリプレグ２の結合部４の溶着樹脂４ａの溶融開始温度が、プリプレグ２の他の部分の樹脂のガラス転移点（Ｔｇ）よりも高くなるように、樹脂硬化度を設定するのが好ましい。
【００２７】
そして、回路板１の収縮率の差が０．０５％以上であるときは、プリプレグ２の結合部４の溶着樹脂４ａの溶融開始温度が１３０℃以上になるように、樹脂硬化度を設定するのが好ましい。プリプレグ２が一般的なＦＲ−４グレードの場合、結合部４の溶着樹脂４ａの溶融開始温度が１３０℃未満であると、加熱加圧成形の際にプリプレグ２の含浸樹脂と共に結合部４の溶着樹脂４ａも再溶融され易くなるので、結合部４の溶着樹脂４ａの溶融開始温度が１３０℃以上になるように設定し、回路板１の位置ずれを防ぐようにするものである。プリプレグ２がＦＲ−５グレードの場合には、溶融開始温度がさらに１６０〜１８０℃程度の高温になるように樹脂硬化度を設定するのが好ましいものであり、場合によっては結合部４の溶着樹脂４ａを完全硬化させて不融状態にまで樹脂硬化度を高めても良い。
【００２８】
上記の各実施の形態では、回路板１の結合を、プリプレグ２の樹脂を部分的に回路板１に熱溶着させることによって行なうようにしたが、ハトメピン６を用いて回路板１を結合するようにしてもよい。すなわち図３に示すように、回路板１の収縮率の差が大きいほうの方向における両端の二辺の各辺縁に沿って少なくとも３箇所に孔５を穿孔加工すると共に回路板１間に挟みこむプリプレグ２に孔５を穿孔加工し、各回路板１及びプリプレグ２の孔５にアルミニウムなどの金属材で筒状に形成されるハトメピン６を挿通して、ハトメピン６の両端をかしめることによって、ハトメピン６の両端に形成される鍔部１１を回路板１の外面に係止させるようにするものであり、このハトメピン６が結合部４となって回路板１を結合することができるものである。
【００２９】
【実施例】
次に、本発明を実施例によって具体的に説明する。
【００３０】
（実施例１）
図４（ａ）に多層プリント配線板を製造する際の積層構成を示す。
【００３１】
そして回路板１として、ガラス織布基材エポキシ樹脂積層板を基板とし、両面に銅箔によって回路１２を形成した５１０×５１０ｍｍサイズのものを二種類用いた。この二種類の回路板１のうち、一方の回路板１ａは、厚みが０．１ｍｍで、残銅率４０％になるように回路１２を形成したものであり、他方の回路板１ｂは、厚みが０．２ｍｍで、残銅率８０％になるように回路１２を形成したものである。また各回路板１ａ，１ｂの周囲の表面に図４（ｂ）に示す８ヶ所において層間ずれ計測マーク１３を銅箔で形成した。
【００３２】
またプリプレグ２として、ガラス織布基材にエポキシ樹脂を含浸して得られたレジンコンテンツ５３質量％、厚み０．１ｍｍのＦＲ−４グレードのものを用いた。このプリプレグ２の含浸樹脂のガラス転移点を測定したところ、１１０℃であった。
【００３３】
そしてまず回路板１の寸法収縮率を直交するタテ方向（例えば図１（ｂ）のイ矢印方向）とヨコ方向（例えば図１（ｂ）のロ矢印方向）について測定した。すなわち、回路板１に設けた各計測マーク１３間の寸法を測定し、次に回路板１の両面にプリプレグ２と銅箔をそれぞれ重ね、後述の多層プリント配線板の成形条件と同じ条件で加熱加圧成形をした後、Ｘ線寸法計測機で回路板１に設けた各計測マーク１３間の寸法を測定する。この後、加熱加圧成形の前後の計測マーク１３間の寸法の差を演算することによって、回路板１のタテ方向とヨコ方向の収縮率を得ることができるものである。
【００３４】
本実施例において、上記の各回路板１ａ，１ｂの寸法収縮率をこの方法で測定したところ、回路板１ａのタテ方向の収縮率は０．０８％、ヨコ方向の収縮率は０．０２％であり、また回路板１ｂのタテ方向の収縮率は０．０２％、ヨコ方向の収縮率は０．０１％であった。従って、回路板１ａ，１ｂ間の収縮率の差はタテ方向で０．０６％、ヨコ方向で０．０１％である。
【００３５】
そこで、回路板１ａ，１ｂの間にプリプレグ２を挟み込み、収縮率の差が大きいタテ方向における両端の辺縁において溶着ヘッドを回路板１ａ，１ｂの各外面に押し当て、０．２ＭＰａで加圧しながら、３００℃で６０秒間加熱して、回路板１ａ，１ｂの内面にプリプレグ２の樹脂を熱溶着させることによって、図１（ａ）のように回路板１ａ，１ｂのタテ方向での両端の辺縁を溶着樹脂４ａによる結合部４で結合した。この条件で熱溶着を行なうことによって、結合部４の溶着樹脂４ａの樹脂硬化度は溶融開始温度として１３５℃であった。また、結合部４による結合箇所の個数は、図１（ｂ）のように各辺縁に沿って等間隔で３箇所ずつの、合計６箇所に設定した。一箇所当りの結合部４の面積は６０ｍｍ²であり、結合部４の総面積は３６０ｍｍ²である。
【００３６】
上記のようにして回路板１ａ，１ｂをプリプレグ２を介して結合した後、回路板１ａ，１ｂの各外面にプリプレグ２及び厚み１８μｍの銅箔からなる金属箔１０を重ね、これを１８０℃、２．４５ＭＰａ、６０分の条件で加熱加圧成形をし、多層プリント配線板を得た。
【００３７】
（実施例２）
回路板１ａ，１ｂを結合部４で結合する箇所の個数を、図２（ａ）のように両端の各辺縁に沿って等間隔で５箇所ずつの、合計１０箇所に設定するようにした。このものでは結合部４の総面積は６００ｍｍ²である。その他は、実施例１と同様にして多層プリント配線板を得た。
【００３８】
（実施例３）
回路板１ａ，１ｂを結合部４で結合する箇所の個数を、図２（ｂ）のように両端の各辺縁に沿って等間隔で９箇所ずつの、合計１８箇所に設定するようにした。このものでは結合部４の総面積は１０８０ｍｍ²である。また熱溶着を０．２ＭＰａ、２５０℃、１８０秒の条件に変更して行なったが、結合部４の溶着樹脂４ａの樹脂硬化度は溶融開始温度として１３５℃であった。その他は、実施例１と同様にして多層プリント配線板を得た。
【００３９】
（実施例４）
回路板１ａ，１ｂを結合する熱溶着を０．２ＭＰａ、２５０℃、２０秒の条件に変更して行なったところ、結合部４の溶着樹脂４ａの樹脂硬化度は溶融開始温度として１２０℃になった。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４０】
（実施例５）
回路板１ａ，１ｂを結合部４で結合する箇所の個数を、図２（ａ）のように両端の各辺縁に沿って等間隔で５箇所ずつの、合計１０箇所に設定するようにし、また熱溶着を０．２ＭＰａ、２５０℃、２０秒の条件に変更して行なった。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４１】
（実施例６）
回路板１ａ，１ｂの結合をハトメピン６を用いて行ない、回路板１ａ，１ｂをハトメピン６で結合する箇所の個数を、収縮率の差が大きい回路板１ａ，１ｂのタテ方向での両端の各辺縁に沿って等間隔で４箇所ずつの、合計８箇所に設定するようにした。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４２】
（比較例１）
回路板１ａ，１ｂを熱溶着して結合するにあたって、結合部４を図６のように四隅に形成するようにし、また熱溶着を０．２ＭＰａ、２５０℃、２０秒の条件に変更して行なった。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４３】
（比較例２）
回路板１ａ，１ｂを熱溶着して結合するにあたって、結合部４を図６のように回路板１ａ，１ｂの四隅に形成するようにし、また熱溶着を０．２ＭＰａ、２５０℃、１８０秒の条件に変更して行なった。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４４】
（比較例３）
回路板１ａ，１ｂの結合をハトメピン６を用いて行ない、ハトメピン６による結合部４を図６のように回路板１ａ，１ｂの四隅に形成するようにした。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４５】
（比較例４）
回路板１ａ，１ｂを熱溶着して結合するにあたって、収縮率の差が小さいヨコ方向（図１（ｂ）のロ矢印方向）における両端の各辺縁に沿って等間隔で３箇所ずつの、合計６箇所に結合部４を形成した。また熱溶着を０．２ＭＰａ、２５０℃、２０秒の条件に変更して行なった。その他は、実施例１と同様にして多層プリント配線板を得た。
【００４６】
上記のようにして実施例１〜６及び比較例１〜４で得た多層プリント配線板について、Ｘ線計測機で回路板１ａと回路板１ｂの各計測マーク１３を観察し、回路板１ａと回路板１ｂの相対応する計測マーク１３のずれの最大部分の寸法を計測することによって、回路板１ａと回路板１ｂのずれ量を測定した。このとき回路板１ａ，１ｂに設けた６対の各計測マーク１３のずれの寸法の平均値を、回路板１ａと回路板１ｂの層間ずれ量とし、結果を表１に示す。
【００４７】
【表１】

【００４８】
【発明の効果】
上記のように本発明の請求項１に係る多層プリント配線板の製造方法は、回路形成した回路板を、少なくとも隣合う回路板間にプリプレグを介して重ね、これを加熱加圧成形することによって、プリプレグによる絶縁接着層を介して複数枚の回路板を積層一体化して多層プリント配線板を製造するにあたって、隣合う回路板において加熱加圧成形によって回路板に発生する収縮率の差が大きい方向での両端の辺縁を結合させ、この状態で加熱加圧成形を行なうようにしたので、収縮率の差が大きい方向で各回路板が寸法収縮によって相互に変位することを規制することができ、収縮率の差からこの方向に回路板が相互に位置ずれすることを抑制することができるものであり、回路板の位置ずれを防止して、回路が層間位置ずれすることを防ぐことができるものである。
【００４９】
また請求項２の発明は、請求項１において、隣合う回路板の収縮率の差が０．０５％大きくなる毎に、隣合う回路板の辺縁を結合させる結合部の総面積を２倍以上にするようにしたので、収縮率の差が大きくなるにつれて結合部の総面積を大きくして結合の強度を高めることができ、回路板が位置ずれすることを有効に防止することができるものである。
【００５０】
また請求項３の発明は、請求項１において、隣合う回路板の収縮率の差が０．０５％大きくなる毎に、隣合う回路板の辺縁を結合させる結合部の数を１．５倍以上にするにしたので、収縮率の差が大きくなるにつれて結合部の数を多くして結合の強度を高めることができ、回路板が位置ずれすることを有効に防止することができるものである。
【００５１】
また請求項４の発明は、請求項１乃至３のいずれかにおいて、隣合う回路板の辺縁を結合するにあたって、プリプレグの樹脂を部分的に回路板に熱溶着させることによって行なうようにしたので、結合用の特別な部材を用いる必要なく、プリプレグを利用して回路板の結合を行なうことができるものである。
【００５２】
また請求項５の発明は、請求項４において、回路板に熱溶着させた部分の樹脂の溶融開始温度がプリプレグの他の部分の樹脂のガラス転移点よりも高くなるように、プリプレグの熱溶着させた部分の樹脂の硬化度を設定するようにしたので、熱溶着させた部分の樹脂は加熱加圧成形の際に溶融し難くなり、熱溶着による回路板の結合強度を高く得ることができ、回路板が位置ずれすることを有効に防止することができるものである。
【００５３】
また請求項６の発明は、請求項４又は５において、隣合う回路板の収縮率の差が０．０５％以上であるとき、回路板に熱溶着させた部分の樹脂の溶融開始温度が１３０℃以上になるように、プリプレグの熱溶着させた部分の樹脂の硬化度を設定するようにしたので、熱溶着させた部分の樹脂は加熱加圧成形の際に溶融し難くなり、熱溶着による回路板の結合強度を高く得ることができ、回路板が位置ずれすることを有効に防止することができるものである。
【００５４】
また請求項７の発明は、請求項１乃至３のいずれかにおいて、隣合う回路板の辺縁を結合するにあたって、回路板及びプリプレグの辺縁に設けた孔にハトメピンを通してかしめることによって行なうようにしたので、ハトメピンによって回路板を強度高く結合することができ、回路板が位置ずれすることを有効に防止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）は加熱加圧成形の工程での層構成の正面図、（ｂ）は回路板の平面図、（ｃ）は多層プリント配線板の正面図である。
【図２】本発明の実施の形態の他の例を示すものであり、（ａ），（ｂ）はそれぞれ回路板の平面図である。
【図３】本発明の実施の形態の他の例の加熱加圧工程での層構成の断面図である。
【図４】実施例を示すものであり、（ａ）は層構成を示す正面図、（ｂ）は回路板の平面図である。
【図５】従来例を示すものであり、（ａ）は加熱加圧成形の工程での層構成の正面図、（ｂ）は多層プリント配線板の正面図である。
【図６】従来例の回路板の平面図である。
【符号の説明】
１回路板
２プリプレグ
３絶縁接着層
４結合部
５孔
６ハトメピン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer printed wiring board, which is performed by laminating a plurality of circuit boards through a prepreg.
[0002]
[Prior art]
For example, the multilayer printed wiring board is manufactured as shown in FIG. In other words, a plurality of inner-layer circuit boards 1 having circuits formed on the surface are used, and a plurality of circuit boards 1 are stacked with prepreg 2 sandwiched between adjacent circuit boards 1 as shown in FIG. Accordingly, the outer layer circuit forming metal foil 10 is overlapped on the outside via the prepreg 2, and this is heated and pressed to form a plurality of insulating adhesive layers 3 formed by melt-curing the resin of the prepreg 2. A multilayer printed wiring board as shown in FIG. 5B in which a single circuit board 1 and metal foil 10 are laminated and integrated can be obtained.
[0003]
In the multilayer printed wiring board manufactured as described above, a plurality of layers of circuits are formed by the plurality of circuit boards 1, and each of these circuits is conductively connected by through holes, via holes, or the like. ing. Accordingly, it is necessary to prevent the plurality of circuit boards 1 from being displaced from each other during the heat-pressure molding, and to stack the circuits in a state where the respective circuits are accurately aligned with each other.
[0004]
Therefore, a plurality of circuit boards 1 are fixed to each other by using eyelet pins 6 and caulking the eyelet pins 6 through the ends of the circuit board 1 and the prepreg 2 as shown by chain lines in FIG. In this state, heating and pressing are performed. As shown in FIG. 6, the coupling portions 4 that are coupled using the eyelet pins 6 are generally set at the four corner portions of the circuit board 1. In this way, by performing heat and pressure molding with a plurality of circuit boards 1 fixed to each other, the circuit boards 1 are prevented from being displaced from each other, and the circuit of each circuit board 1 is accurately positioned. A laminated multilayer printed wiring board can be obtained.
[0005]
[Problems to be solved by the invention]
The circuit board 1 used for the production of the multilayer printed wiring board is formed by stacking a plurality of prepregs prepared by impregnating and drying a thermosetting resin varnish on a glass cloth or the like, and overlaying a metal foil such as a copper foil on the outside thereof. The metal foil-clad laminate is produced by heat-press molding, and the metal foil of the metal foil-clad laminate is etched to form a circuit. When a plurality of the circuit boards 1 are used and formed into a multilayer by heat and pressure molding as described above, dimensional shrinkage occurs in the circuit board 1 after the heat and pressure molding.
[0006]
Here, since the glass cloth which is the base material of the circuit board 1 has a different number of weaves in the vertical direction and the horizontal direction, when the circuit board 1 is dimensionally contracted by heating and pressing, the circuit board 1 is in the vertical direction and the horizontal direction. Shrinkage is different. Also, the shrinkage rate differs between the vertical direction and the horizontal direction depending on the circuit pattern formed on the circuit board 1. Therefore, the shrinkage rate in the direction between the two opposite sides of the circuit board 1 formed in a square or rectangular shape is different from the shrinkage rate in the direction between the two opposite sides perpendicular to the circuit board 1, so that they are laminated. In general, the shrinkage rates of the plurality of circuit boards 1 differ depending on the direction. The plurality of circuit boards 1 to be laminated differ greatly in contraction rate depending on their thickness and layer configuration. For this reason, in the direction in which the difference in shrinkage rate is large between the circuit boards 1 to be laminated, the difference in shrinkage rate is often 0.05% or more.
[0007]
However, if there is a large difference in shrinkage between the circuit boards 1 stacked next to each other, the shrinkage is caused even if the heat and pressure molding is performed with the four corners fixed by the joints 4 such as the eyelet pins 6 as described above. The problem is that the adjacent circuit boards 1 cannot be prevented from being displaced in the direction in which the rate difference is large, and the circuit formed on each circuit board 1 may be displaced between layers. .
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a multilayer printed wiring board that can prevent the circuit board from being displaced and prevent the circuit from being displaced between the layers. It is what.
[0009]
[Means for Solving the Problems]
In the method for producing a multilayer printed wiring board according to claim 1 of the present invention, the circuit board 1 on which the circuit is formed is overlapped at least between the adjacent circuit boards 1 via the prepreg 2, and this is heated and pressed. When a multilayer printed wiring board is manufactured by laminating and integrating a plurality of circuit boards 1 via an insulating adhesive layer 3 by a prepreg 2, the shrinkage rate generated in the circuit board 1 by heating and pressing in the adjacent circuit boards 1 is reduced. The edges of both ends in the direction in which the difference is large are combined, and heating and pressing are performed in this state.
[0010]
The invention of claim 2 provides the total area of the coupling portion 4 for joining the edges of the adjacent circuit boards 1 each time the difference in shrinkage between the adjacent circuit boards 1 is increased by 0.05%. Is characterized in that it is doubled or more.
[0011]
According to a third aspect of the present invention, in the first aspect, each time the difference in shrinkage between adjacent circuit boards 1 is increased by 0.05%, the number of connecting portions 4 for connecting the edges of the adjacent circuit boards 1 is increased. It is characterized by being 1.5 times or more.
[0012]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the resin of the prepreg 2 is partially thermally welded to the circuit board 1 when connecting the edges of the adjacent circuit boards 1. It is characterized by.
[0013]
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the prepreg 2 is formed such that the melting start temperature of the resin in the portion thermally welded to the circuit board 1 is higher than the glass transition point of the resin in the other portion of the prepreg 2. The degree of curing of the resin in the heat-welded portion is set.
[0014]
According to a sixth aspect of the present invention, in the fourth or fifth aspect, when the difference in shrinkage between adjacent circuit boards 1 is 0.05% or more, the melting start temperature of the resin thermally welded to the circuit board 1 The degree of cure of the resin in the portion where the prepreg 2 is thermally welded is set so that the temperature becomes 130 ° C. or higher.
[0015]
According to a seventh aspect of the present invention, in any one of the first to third aspects, when the edges of the adjacent circuit boards 1 are coupled, the eyelet pins 6 are passed through the holes 5 provided in the edges of the circuit board 1 and the prepreg 2. It is characterized by being performed by squeezing.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0017]
As the circuit board 1 in the present invention, any circuit board used as an inner layer circuit board or the like can be used. That is, a base material such as a glass cloth is impregnated with a thermosetting resin varnish such as an epoxy resin and dried by heating, and a plurality of the prepregs are stacked and a metal foil such as a copper foil is stacked on the outside. A metal foil-clad laminate can be produced by heat-pressing this, and a product produced by forming a circuit by etching the metal foil of the metal foil-clad laminate can be used.
[0018]
Further, as the prepreg 2, any one used for multilayer molding or the like can be used. That is, use what was manufactured by impregnating a base material such as glass cloth with a thermosetting resin varnish such as an epoxy resin, and drying and heating the impregnated thermosetting resin into a semi-cured state. Can do.
[0019]
A multilayer printed wiring board can be manufactured by using the plurality of circuit boards 1 as an inner layer material, and heating and press-molding the plurality of circuit boards 1 through a prepreg 2 and stacking and integrating them. However, the shrinkage rate of the circuit board 1 is measured prior to this molding. The measurement of the shrinkage ratio of the circuit board 1 is performed by heating and press-molding the circuit board 1 under the same molding conditions as those for manufacturing the multilayer printed wiring board, and the dimensions before heating and press-molding. This can be done by measuring the dimensions, and the shrinkage rate can be determined from the difference in dimensions. The measurement of the shrinkage rate is performed in two orthogonal directions, that is, a direction between two opposing sides of the circuit board 1 formed in a square or rectangular shape and a direction between two other opposing sides. Of course, the shrinkage rate may be measured only for the circuit board 1 extracted as a sample.
[0020]
Then, when stacking a plurality of (two in the illustrated embodiment) circuit boards 1 with one or a plurality of prepregs 2 sandwiched between adjacent circuit boards 1, the circuit boards 1 are not displaced from each other. To join. For example, in the state where the prepreg 2 is sandwiched between the two circuit boards 1, the bonding is performed by pressing a welding head or the like on the outer surface of the circuit board 1 on both sides in a spot shape and heating while applying pressure. This can be performed by melting and solidifying the semi-cured resin impregnated in the prepreg 2 and thermally welding the resin to the inner surface of each circuit board 1. The welding resin of the prepreg 2 to be welded to the circuit board 1 The circuit board 1 can be coupled with the coupling portion 4a.
[0021]
Here, in the present invention, in the two circuit boards 1 stacked via the prepreg 2, the difference between the shrinkage rates in the same direction between the two opposite sides (the direction of the arrow B in FIG. 1B) is orthogonal to this. The difference in contraction rate in the direction between the two opposite sides (the arrow B direction in FIG. 1B) is obtained, and the direction in which the difference in contraction rate is larger (for example, the arrow A direction in FIG. 1B) ) Along the two edges at both ends in FIG. 1B, as shown in FIGS. 1B and 2A and 2B, the coupling is performed at a plurality of at least three locations.
[0022]
Next, one or a plurality of prepregs 2 and a plurality of prepregs 2 as shown in FIG. A plurality of sheets of insulating adhesive layer 3 formed by melting and curing the impregnating resin of prepreg 2 as shown in FIG. A multilayer printed wiring board in which the circuit board 1 and the metal foil 10 for the outer layer circuit are laminated and integrated can be manufactured. In this way, when performing the heat and pressure molding, the plurality of circuit boards 1 are coupled to each other by the coupling portion 4, so that they can be prevented from being displaced from each other during molding. In addition, each circuit board 1 shrinks in size due to heat and pressure molding, but each circuit board 1 is coupled along each of the two edges at both ends in the direction in which the difference in shrinkage is larger. Thus, the displacement of the circuit boards 1 due to dimensional shrinkage can be restricted, and the displacement of the circuit boards 1 in this direction can be suppressed from the difference in shrinkage rate. Therefore, it is possible to prevent a positional shift of each circuit board 1 and obtain a multilayer printed wiring board in which the circuits of each circuit board 1 are accurately aligned.
[0023]
Here, when connecting the adjacent circuit boards 1 along the respective edges of the two sides at both ends in the direction in which the difference in contraction ratio is larger as described above, the contraction ratio between the circuit boards 1 is If the difference increases, the difference in displacement due to the dimensional shrinkage of each circuit board 1 increases. Therefore, unless the coupling strength is increased, it is difficult to suppress the displacement of the circuit boards 1 due to mutual displacement.
[0024]
Therefore, in the present invention, as the difference in contraction rate between the circuit boards 1 increases, the total area at each edge of the connecting portion 4 provided along each edge of the two sides is increased. It is preferable to increase the strength of the coupling between the circuit boards 1. Specifically, it is preferable that the total area of the coupling portion 4 that couples the edges of the circuit board 1 is doubled or more each time the difference in shrinkage of the circuit board 1 increases by 0.05%. For example, when the difference in shrinkage rate is 0.05%, the total area of the coupling portion 4 where the positional deviation of the circuit board 1 does not occur is obtained experimentally, and when the difference in shrinkage rate is 0.1%, the total The coupling portion 4 is formed with an area that is twice or more the area.
[0025]
Further, as the difference in contraction rate between the circuit boards 1 increases, the number of the connecting portions 4 provided along each of the two sides is increased, and the connection between the circuit boards 1 by the connecting portions 4 is increased. The strength can also be increased. Specifically, it is preferable to increase the number of coupling portions 4 for coupling the edges of the circuit board 1 to 1.5 times or more each time the difference in shrinkage of the circuit board 1 increases by 0.05%. For example, when the difference in shrinkage rate is 0.05%, the number of coupling portions 4 where the positional deviation of the circuit board 1 does not occur is obtained experimentally, and when the difference in shrinkage rate is 0.1% The coupling portions 4 are formed with a number 1.5 times or more.
[0026]
Further, when the circuit board 1 is bonded by partially thermally bonding the resin of the prepreg 2 to the circuit board 1 as described above, the bonding resin 4a of the bonding portion 4 has higher bonding strength when the resin curing degree is higher. Become. That is, since the melting start temperature becomes high when the resin curing degree is high, the welding resin 4a of the joint portion 4 having a high resin curing degree is difficult to melt during the heat and pressure molding when manufacturing the multilayer printed wiring board, It is possible to obtain a high bonding strength between the circuit boards 1 by the welding resin 4a. Adjustment of the resin curing degree of the welding resin 4a of the coupling portion 4 is performed by pressing a welding head or the like against the outer surface of the circuit board 1 with the prepreg 2 sandwiched between the two circuit boards 1, When performing welding, the heating temperature and the heating time can be controlled to adjust the crosslinking density of the welding resin 4a. Specifically, the resin curing degree is set so that the melting start temperature of the welding resin 4a of the joint portion 4 of the prepreg 2 is higher than the glass transition point (Tg) of the resin in other portions of the prepreg 2. Is preferred.
[0027]
When the difference in shrinkage between the circuit boards 1 is 0.05% or more, the resin curing degree is set so that the melting start temperature of the welding resin 4a of the joint portion 4 of the prepreg 2 is 130 ° C. or more. Is preferred. When the prepreg 2 is a general FR-4 grade, if the melting start temperature of the weld resin 4a of the joint portion 4 is less than 130 ° C., the joint portion 4 is welded together with the impregnating resin of the prepreg 2 during the heat and pressure molding. Since the resin 4a is easily remelted, the melting start temperature of the welding resin 4a of the joint 4 is set to be 130 ° C. or higher to prevent the circuit board 1 from being displaced. When the prepreg 2 is of the FR-5 grade, it is preferable to set the resin curing degree so that the melting start temperature becomes a high temperature of about 160 to 180 ° C. In some cases, the welding resin of the bonding portion 4 4a may be completely cured to increase the resin curing degree to an infusible state.
[0028]
In each of the above embodiments, the circuit board 1 is coupled by partially thermally bonding the resin of the prepreg 2 to the circuit board 1. However, the circuit board 1 is coupled using the eyelet pins 6. It may be. That is, as shown in FIG. 3, at least three holes 5 are drilled along the two edges on both ends in the direction in which the difference in contraction rate of the circuit board 1 is larger and sandwiched between the circuit boards 1. By drilling holes 5 in the prepreg 2, inserting the eyelet pins 6 formed in a cylindrical shape with a metal material such as aluminum into the holes 5 of each circuit board 1 and the prepreg 2, and crimping both ends of the eyelet pins 6. The hooks 11 formed at both ends of the eyelet pins 6 are locked to the outer surface of the circuit board 1, and the eyelet pins 6 can be connected to the circuit board 1 as the connecting parts 4. is there.
[0029]
【Example】
Next, the present invention will be specifically described with reference to examples.
[0030]
Example 1
FIG. 4A shows a laminated configuration when manufacturing a multilayer printed wiring board.
[0031]
And as the circuit board 1, the glass woven fabric base material epoxy resin laminated board was used as a board | substrate, and the thing of 510 * 510mm size which formed the circuit 12 with copper foil on both surfaces was used. Of these two types of circuit boards 1, one circuit board 1 a has a thickness of 0.1 mm and a circuit 12 formed so as to have a remaining copper ratio of 40%, and the other circuit board 1 b has a thickness. Is a circuit 12 formed so that the remaining copper ratio is 80%. Further, interlayer displacement measurement marks 13 were formed of copper foil at eight locations shown in FIG. 4B on the surface around each circuit board 1a, 1b.
[0032]
Further, as the prepreg 2, an FR-4 grade resin content 53% by mass obtained by impregnating a glass woven fabric base material with an epoxy resin and a thickness of 0.1 mm was used. It was 110 degreeC when the glass transition point of the impregnation resin of this prepreg 2 was measured.
[0033]
First, the dimensional shrinkage rate of the circuit board 1 was measured in the vertical direction (for example, the arrow direction in FIG. 1B) and the horizontal direction (for example, the arrow direction in FIG. 1B). That is, the dimension between each measurement mark 13 provided on the circuit board 1 is measured, and then the prepreg 2 and the copper foil are respectively overlapped on both sides of the circuit board 1 and heated under the same conditions as those for forming a multilayer printed wiring board described later. After pressure forming, the dimension between the measurement marks 13 provided on the circuit board 1 is measured with an X-ray dimension measuring machine. Thereafter, the contraction rate in the vertical direction and the horizontal direction of the circuit board 1 can be obtained by calculating the dimensional difference between the measurement marks 13 before and after the heat and pressure molding.
[0034]
In this embodiment, when the dimensional shrinkage rate of each of the circuit boards 1a and 1b was measured by this method, the shrinkage rate in the vertical direction of the circuit board 1a was 0.08%, and the shrinkage rate in the horizontal direction was 0.02%. Further, the contraction rate in the vertical direction of the circuit board 1b was 0.02%, and the contraction rate in the horizontal direction was 0.01%. Accordingly, the difference in shrinkage between the circuit boards 1a and 1b is 0.06% in the vertical direction and 0.01% in the horizontal direction.
[0035]
Therefore, the prepreg 2 is sandwiched between the circuit boards 1a and 1b, the welding heads are pressed against the outer surfaces of the circuit boards 1a and 1b at both edges in the vertical direction where the difference in shrinkage is large, and the pressure is applied at 0.2 MPa. However, by heating at 300 ° C. for 60 seconds and thermally welding the resin of the prepreg 2 to the inner surfaces of the circuit boards 1a and 1b, both ends of the circuit boards 1a and 1b in the vertical direction as shown in FIG. The edges were joined at the joint 4 by the welding resin 4a. By performing heat welding under these conditions, the resin curing degree of the welding resin 4a of the joint portion 4 was 135 ° C. as the melting start temperature. In addition, the number of places to be joined by the joining portion 4 was set to a total of six places, three places at equal intervals along each edge as shown in FIG. The area of the coupling part 4 per one place is 60 mm ² , and the total area of the coupling part 4 is 360 mm ² .
[0036]
After the circuit boards 1a and 1b are coupled via the prepreg 2 as described above, the metal foil 10 made of copper foil having a thickness of 18 μm and the prepreg 2 is stacked on each outer surface of the circuit boards 1a and 1b. Heat-press molding was performed under conditions of 2.45 MPa and 60 minutes to obtain a multilayer printed wiring board.
[0037]
(Example 2)
The number of places where the circuit boards 1a and 1b are joined by the joining portion 4 is set to a total of 10 places, 5 places at equal intervals along each edge of both ends as shown in FIG. 2 (a). . In this case, the total area of the coupling portion 4 is 600 mm ² . Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0038]
(Example 3)
The number of places where the circuit boards 1a and 1b are joined by the joining portion 4 is set to 18 places, 9 places at equal intervals along each edge of both ends as shown in FIG. 2 (b). . In this case, the total area of the connecting portion 4 is 1080 mm ² . Further, the thermal welding was performed under the conditions of 0.2 MPa, 250 ° C., and 180 seconds, but the resin curing degree of the welding resin 4a of the joint 4 was 135 ° C. as the melting start temperature. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0039]
(Example 4)
When the thermal welding for bonding the circuit boards 1a and 1b was changed to the conditions of 0.2 MPa, 250 ° C., and 20 seconds, the resin curing degree of the welding resin 4a of the bonding portion 4 became 120 ° C. as the melting start temperature. It was. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0040]
(Example 5)
The number of places where the circuit boards 1a and 1b are joined by the joining portion 4 is set to 10 places in total at 5 places along each edge of both ends as shown in FIG. Further, the thermal welding was performed under the conditions of 0.2 MPa, 250 ° C., and 20 seconds. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0041]
(Example 6)
The circuit boards 1a and 1b are connected using the eyelet pins 6, and the number of locations where the circuit boards 1a and 1b are connected by the eyelet pins 6 is determined by connecting the circuit boards 1a and 1b at both ends of the circuit boards 1a and 1b in the vertical direction. A total of 8 places were set, 4 places at regular intervals along the edge. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0042]
(Comparative Example 1)
When the circuit boards 1a and 1b are bonded by heat welding, the bonding portions 4 are formed at the four corners as shown in FIG. 6, and the heat welding is changed to the conditions of 0.2 MPa, 250 ° C. and 20 seconds. It was. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0043]
(Comparative Example 2)
When the circuit boards 1a and 1b are thermally welded and joined, the joint portions 4 are formed at the four corners of the circuit boards 1a and 1b as shown in FIG. 6, and the thermal welding is performed at 0.2 MPa, 250 ° C., 180 seconds. Changed to conditions. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0044]
(Comparative Example 3)
The circuit boards 1a and 1b are coupled using the eyelet pins 6, and the coupling parts 4 by the eyelet pins 6 are formed at the four corners of the circuit boards 1a and 1b as shown in FIG. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0045]
(Comparative Example 4)
When the circuit boards 1a and 1b are bonded by heat welding, the difference between the shrinkage rates is small (three directions at equal intervals along the edges of both ends in the horizontal direction (arrow B direction in FIG. 1B)). The joint part 4 was formed in a total of six places. Further, the thermal welding was performed under the conditions of 0.2 MPa, 250 ° C., and 20 seconds. Other than that, a multilayer printed wiring board was obtained in the same manner as in Example 1.
[0046]
With respect to the multilayer printed wiring boards obtained in Examples 1 to 6 and Comparative Examples 1 to 4 as described above, the measurement marks 13 on the circuit board 1a and the circuit board 1b are observed with an X-ray measuring machine, and the circuit board 1a and The amount of deviation between the circuit board 1a and the circuit board 1b was measured by measuring the dimension of the maximum portion of the deviation of the corresponding measurement mark 13 on the circuit board 1b. At this time, the average value of the displacement dimensions of the six pairs of measurement marks 13 provided on the circuit boards 1a and 1b is defined as the amount of interlayer displacement between the circuit boards 1a and 1b, and the results are shown in Table 1.
[0047]
[Table 1]

[0048]
【The invention's effect】
As described above, the method for producing a multilayer printed wiring board according to claim 1 of the present invention includes stacking circuit boards formed with circuits via at least prepregs between adjacent circuit boards, and heating and pressing the circuit boards. When manufacturing a multilayer printed wiring board by laminating and integrating a plurality of circuit boards via an insulating adhesive layer made of prepreg, the direction in which the difference in shrinkage ratio generated in the circuit board by heating and pressing is large in adjacent circuit boards In this state, the edges of both ends are joined and heat and pressure molding is performed, so that it is possible to regulate the mutual displacement of the circuit boards due to dimensional shrinkage in the direction in which the difference in shrinkage is large. The circuit board can be prevented from being displaced from each other in this direction due to the difference in shrinkage rate, preventing the circuit board from being displaced and preventing the circuit from being displaced between the layers. One in which it is bet.
[0049]
Further, the invention of claim 2 is the invention according to claim 1, wherein each time the difference in shrinkage between adjacent circuit boards is increased by 0.05%, the total area of the joints connecting the edges of the adjacent circuit boards is doubled. As described above, as the difference in shrinkage rate increases, the total area of the coupling portion can be increased to increase the strength of the coupling, and the circuit board can be effectively prevented from being displaced. It is.
[0050]
According to a third aspect of the present invention, in the first aspect, every time the difference in shrinkage between adjacent circuit boards is increased by 0.05%, the number of connecting portions for connecting the edges of adjacent circuit boards is 1.5. As the difference in shrinkage ratio increases, the number of coupling portions can be increased to increase the strength of coupling, and the circuit board can be effectively prevented from being displaced. is there.
[0051]
According to a fourth aspect of the present invention, in any one of the first to third aspects, when the edges of adjacent circuit boards are joined, the resin of the prepreg is partially thermally welded to the circuit board. The circuit boards can be coupled using a prepreg without using a special member for coupling.
[0052]
According to a fifth aspect of the present invention, in the fourth aspect, the prepreg is thermally welded so that the melting start temperature of the portion of the resin thermally welded to the circuit board is higher than the glass transition point of the resin of the other portion of the prepreg. Since the degree of cure of the resin of the part that has been made is set, the resin of the part that has been heat-welded is difficult to melt during heat-pressure molding, and the bond strength of the circuit board by heat-welding can be obtained high. The circuit board can be effectively prevented from being displaced.
[0053]
According to a sixth aspect of the present invention, when the difference in shrinkage between adjacent circuit boards is 0.05% or more in the fourth or fifth aspect, the melting start temperature of the resin in the portion thermally welded to the circuit board is 130. Since the degree of curing of the resin of the part where the prepreg is heat-welded is set so that the temperature is higher than or equal to ℃, the resin of the heat-welded part becomes difficult to be melted during heat-pressure molding, It is possible to obtain a high coupling strength of the circuit board and to effectively prevent the circuit board from being displaced.
[0054]
According to a seventh aspect of the present invention, in any one of the first to third aspects, when the edges of the adjacent circuit boards are coupled, the eyelet pins are caulked through holes provided in the edges of the circuit board and the prepreg. Thus, the circuit board can be coupled with high strength by the eyelet pin, and the circuit board can be effectively prevented from being displaced.
[Brief description of the drawings]
1A and 1B show an example of an embodiment of the present invention, in which FIG. 1A is a front view of a layer structure in a heat and pressure molding process, FIG. 1B is a plan view of a circuit board, and FIG. It is a front view of a multilayer printed wiring board.
FIGS. 2A and 2B show another example of the embodiment of the present invention, and FIGS. 2A and 2B are plan views of circuit boards, respectively. FIGS.
FIG. 3 is a cross-sectional view of a layer configuration in a heating and pressing process according to another example of the embodiment of the present invention.
4A and 4B show an embodiment, in which FIG. 4A is a front view showing a layer structure, and FIG. 4B is a plan view of a circuit board.
FIGS. 5A and 5B show a conventional example, in which FIG. 5A is a front view of a layer structure in a heating and pressing process, and FIG. 5B is a front view of a multilayer printed wiring board.
FIG. 6 is a plan view of a conventional circuit board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Circuit board 2 Prepreg 3 Insulation adhesive layer 4 Connection part 5 Hole 6 Eyelet pin

Claims

Circuit boards with circuit formation are stacked at least between adjacent circuit boards via a prepreg, and this is heated and pressed to laminate and integrate multiple circuit boards via an insulating adhesive layer made of prepreg. When manufacturing a wiring board, the edges of both ends in the direction in which the difference in contraction rate generated in the circuit board by the heat and pressure molding in the adjacent circuit board is large are combined, and the heat and pressure molding is performed in this state. A method for producing a multilayer printed wiring board, which is characterized.

2. The total area of the coupling portion for coupling the edges of adjacent circuit boards is more than doubled every time the difference in shrinkage between adjacent circuit boards increases by 0.05%. Manufacturing method for multilayer printed wiring boards.

The number of coupling portions for coupling the edges of adjacent circuit boards is increased by 1.5 times or more every time the difference in shrinkage between adjacent circuit boards is increased by 0.05%. The manufacturing method of the multilayer printed wiring board as described.

The multilayer printed wiring board according to any one of claims 1 to 3, wherein the edges of adjacent circuit boards are joined by partially thermally welding a resin of a prepreg to the circuit board. Method.

Setting the degree of curing of the resin in the heat-welded part of the prepreg so that the melting start temperature of the resin in the part heat-welded to the circuit board is higher than the glass transition point of the resin in the other part of the prepreg. The manufacturing method of the multilayer printed wiring board of Claim 4 characterized by the above-mentioned.

When the difference in shrinkage between adjacent circuit boards is 0.05% or more, the heat-welded part of the prepreg is heated so that the melting start temperature of the resin of the part heat-welded to the circuit board is 130 ° C. or higher. 6. The method for producing a multilayer printed wiring board according to claim 4, wherein the degree of cure of the resin is set.

The multilayer printed wiring according to any one of claims 1 to 3, wherein the edges of adjacent circuit boards are joined by caulking a grommet pin into holes provided in the edges of the circuit board and the prepreg. A manufacturing method of a board.