JP4590689B2

JP4590689B2 - Printed wiring board connection method and connection structure

Info

Publication number: JP4590689B2
Application number: JP2000188278A
Authority: JP
Inventors: 眞戸谷; 知之名波; 健三平野; 敏広三宅; 雄史寺前; 智宏横地
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 1999-11-30
Filing date: 2000-06-22
Publication date: 2010-12-01
Anticipated expiration: 2020-06-22
Also published as: JP2001223465A

Description

【０００１】
【発明の属する技術分野】
本発明は、プリント配線基板の接続方法及び接続構造に関するものである。
【０００２】
【従来の技術】
従来、プリント配線基板の接続構造として、異方導電樹脂材料を用いたものが知られている（特開平９−８４５３号公報）。これは、図９に示すように、第１のプリント配線基板５０における導体パターン形成面と第２のプリント配線基板５１における導体パターン形成面との間に、異方導電性の熱可塑性樹脂５２を配置し、圧力と超音波によって熱可塑性樹脂５２を溶融するものである。これによってランド５０ａ，５０ｂ間の間隔を狭めて、両者の電気的接続を行う。
【０００３】
また、「高密度フレキシブル基板入門」（沼倉研史著、日刊工業新聞社発行）の第１００頁には、半田熱融着による硬質プリント基板とフレキシブル基板の接続方法について示されている。この接続方法によれば、図１０に示すように、硬質プリント基板６０の導体パターンのランド６０ａとフレキシブル基板６１の導体パターンのランド６１ａとを半田６２によって接続する。さらに、フレキシブル基板６１は接着剤６３を介して硬質プリント基板６０に接着される。
【０００４】
【発明が解決しようとする課題】
しかし、図９に示す接続構造では、異方導電樹脂膜をプリント配線基板５０，５１の表面に印刷したり、あるいは異方導電樹脂フィルムをプリント配線基板５０，５１の表面に載置しなければならない。このため、接続構造を得るための工程が増加し、製造コストアップの要因となる。また、異方導電樹脂材料５２を介在させた状態で、プリント配線基板５０，５１の表面同士を向かい合わせて接続するため、樹脂材料５２とプリント配線基板５０，５１との接着界面にボイドが発生しやすく、信頼性に劣る。
【０００５】
また、図１０に示す接続構造では、接続箇所の絶縁信頼性を確保するために、フレキシブル基板６１の接続後に、フレキシブル基板６１の端部を保護用絶縁フィルム等で覆う必要があり、やはり製造工程が増加するという問題がある。
【０００６】
本発明は、かかる従来の問題点を鑑みてなされたもので、接続信頼性の向上および製造コストの低減を図ることが可能なプリント配線基板の接続方法及び接続構造を提供することを目的とする。
【０００７】
【課題を解決するための手段】
請求項１に記載のプリント配線基板の接続方法は、絶縁基板材料として熱可塑性樹脂を用いた第１のプリント配線基板の接続面において、接続面先端部分を除く領域に、接続端子としてのランドを含む導体パターンを形成する工程と、
第１のプリント配線基板の接続面先端部分を第２のプリント配線基板の接続面上に配置した状態で、第１のプリント配線基板の接続面に形成した導体パターンのランドと、第２のプリント配線基板の接続面に形成した導体パターンのランドとを重ねて配置する工程と、
前記第１のプリント配線基板と前記第２のプリント配線基板との接続箇所を前記熱可塑性樹脂のガラス転移温度以上に加熱するとともに、当該部位に圧力を加えて、前記第１のプリント配線基板のランドと前記第２のプリント配線基板のランドとを電気的に接続するとともに、前記第１のプリント配線基板を構成する熱可塑性樹脂を軟化変形させ、前記接続面先端部の熱可塑性樹脂を前記第２のプリント配線基板の接続面に密着させるとともに接続箇所における導体パターンを熱可塑性樹脂にて封止する工程とを備え、
熱可塑性樹脂は、ポリエーテルエーテルケトン樹脂を６５〜３５重量％とポリエーテルイミド樹脂を３５〜６５重量％含む単層からなる。
【０００８】
このように、異方導電性フィルム等を用いることなく、第１のプリント配線基板自身の変化による変形性を利用し、端子接続とともに接続箇所を樹脂封止することができるので製造コストの低減を図ることができる。また、第１のプリント配線基板の接続面先端部に導体パターンが形成されない領域を設け、その接続面先端部を第２のプリント配線基板の接続面に密着させるので、確実に接続箇所におけるランド、導体パターンを封止できる。
【０００９】
また、請求項７記載のプリント配線基板の接続方法は、絶縁基板材料としてポリエーテルエーテルケトン樹脂を６５〜３５重量％とポリエーテルイミド樹脂を３５〜６５重量％含む単層の熱可塑性樹脂を用いた第１のプリント配線基板の接続面に、接続端子としてのランドを含む導体パターンを形成する工程と、
前記導体パターンのランドを除いて、当該導体パターンを保護膜にて被覆するとともに、前記第１のプリント配線基板の接続面端部近傍にも当該保護膜を形成する工程と、
前記第１のプリント配線基板に形成した導体パターンのランドと、第２のプリント配線基板の接続面に形成した導体パターンのランドとを接続材料を介して重ねて配置する工程と、
前記第１のプリント配線基板と前記第２のプリント配線基板との接続箇所を前記熱可塑性樹脂のガラス転移温度以上に加熱するとともに、当該部位に圧力を加えて、前記第１のプリント配線基板のランドと前記第２のプリント配線基板のランドとを前記接続材料を介して電気的に接続するとともに、前記第１のプリント配線基板を構成する熱可塑性樹脂を軟化変形させ、接続箇所における導体パターンを熱可塑性樹脂にて封止する工程とを備え、
前記第１のプリント配線基板の接続面端部に形成された保護膜が前記接続材料の接続面外部への流動を遮断することを特徴とする。
【００１０】
これにより、第１及び第２のプリント配線基板のランド間の接続材料の量が過剰で、両プリント配線基板の接続時に流動しても、第１のプリント配線基板の接続面端部に形成された保護膜がその流動を遮断するので、接続箇所における絶縁信頼性を向上することができる。
【００１１】
さらに、請求項１４に記載のプリント配線基板の接続方法は、絶縁基板材料として熱可塑性樹脂を用いた第１のプリント配線基板の接続面に、接続端子としてのランドを含む導体パターンを形成する工程と、
前記導体パターンのランドを除いて、当該導体パターンを保護膜にて被覆する際に、その保護膜の端部において、導体パターンを被覆しつつ、その両側の第１のプリント配線基板の表面を露出させるように凸状部分を形成する工程と、
第２のプリント配線基板の接続面先端部から所定距離離れた位置において、導体パターンの端部が終端するように、接続端子としてのランドを含む導体パターンを第２のプリント配線基板上に形成する工程と、
第１のプリント配線基板に形成した導体パターンのランドと、第２のプリント配線基板の接続面に形成した導体パターンのランドとを重ね、かつ前記露出された第１のプリント配線基板の表面が前記第２のプリント配線基板の接続面先端部に対向するように配置する工程と、
前記第１のプリント配線基板と前記第２のプリント配線基板との接続箇所を前記熱可塑性樹脂のガラス転移温度以上に加熱するとともに、当該部位に圧力を加えて、前記第１のプリント配線基板のランドと前記第２のプリント配線基板のランドとを前記接続材料を介して電気的に接続するとともに、前記第１のプリント配線基板を構成する熱可塑性樹脂を軟化変形させ、前記保護膜から露出された部分の第１のプリント配線基板の熱可塑性樹脂が前記第２のプリント配線基板の接続面先端部に密着するとともに接続箇所における導体パターンを熱可塑性樹脂にて封止する工程とを備え、第１のプリント配線基板の接続面において、導体パターンは接続面先端部分から所定距離離れた位置で終端するように形成されており、その接続面先端部分の熱可塑性樹脂が、第２のプリント配線基板の接続面に密着され、
熱可塑性樹脂は、ポリエーテルエーテルケトン樹脂を６５〜３５重量％とポリエーテルイミド樹脂を３５〜６５重量％含む単層からなることを特徴とする。
【００１２】
これにより、第１のプリント配線基板と第２のプリント配線基板の接続箇所で最も応力がかかる第２のプリント配線基板の先端部における接着強度を向上することができる。さらに、第２のプリント配線基板の先端部に位置する第１のプリント配線基板の導体パターンが熱可塑性樹脂と第２のプリント配線基板とによって取り囲まれるように封止されるので、その樹脂封止の信頼性を向上させることができる。
【００１３】
なお、請求項１７，２３，３０に記載のプリント配線基板の接続構造は、それぞれ上述の請求項１，７，１４によるプリント配線基板の接続方法によって得られるものであり、それらの効果は上述の内容とほぼ同様である。
【００１４】
【発明の実施の形態】
（第１の実施の形態）
以下、本発明の第１の実施の形態を図面に基づいて説明する。
【００１５】
図１に、本第１実施形態における電子機器の一部を示す。電子機器の内部において、リジッドプリント配線基板１とリジッドプリント配線基板２とが支持されている。リジッドプリント配線基板１には各種の電子部品が実装されており、図１においては、ＤＩＰパッケージのＩＣ３がピン３ａを介して実装されている状態を示している。同様に、リジッドプリント配線基板２にも各種の電子部品４が実装されている。これらリジッドプリント配線基板１、２の絶縁基板１０の材料としては、例えばガラス布基材エポキシ樹脂を使用することができる。
【００１６】
上下に水平に配置されたリジッドプリント配線基板１とリジッドプリント配線基板２のそれぞれの基板端部間にフレキシブルプリント配線基板５が接続され、両者の電気的な導通をとっている。このフレキシブルプリント配線基板５の絶縁基板１２の材料として、ポリエーテルエーテルケトン（ＰＥＥＫ）樹脂を６５〜３５重量％とポリエーテルイミド（ＰＥＩ）樹脂を３５〜６５重量％含む熱可塑性樹脂（＠ＰＥＥＫ）が使用されている。この＠ＰＥＥＫは、ガラス転移温度以上の温度において軟化する熱可塑性樹脂である。
【００１７】
図２は、リジッドプリント配線基板２とフレキシブルプリント配線基板５の接続箇所を拡大して示している。
【００１８】
リジッドプリント配線基板２の上面には複数の導体パターン１１が形成され、基板端部から所定距離離れた位置において終端する導体パターン１１の端部にはランド１１ａが形成されている。このランド１１ａ上には、接続材料として半田１４が塗布される。フレキシブルプリント配線基板５の表面にも、リジッドプリント配線基板２上の導体パターン１１に対応して、複数の導体パターン１３が形成され、それらの端部には接続端子としてのランド１３ａが形成されている。これらの導体パターン１１，１３は、銅によって構成される。
【００１９】
リジッドプリント配線基板２とフレキシブルプリント配線基板５の接続箇所において、導体パターン１１のランド１１ａと導体パターン１３のランド１３ａとが半田１４によって接続されるとともに、リジッドプリント配線基板２を構成するガラスエポキシ樹脂１０とフレキシブルプリント配線基板５を構成する＠ＰＥＥＫ１２とが、＠ＰＥＥＫ１２が変形することにより導体パターン１１，１３間において接着されている。さらに、リジッドプリント配線基板２の端部のガラスエポキシ樹脂１０は、フレキシブルプリント配線基板５にランド１３ａ部分以外の導体パターン１３を覆うように形成されたソルダーレジスト１６に接着される。また、フレキシブルプリント配線基板５の端部の＠ＰＥＥＫ１２は、リジッドプリント配線基板２にランド１１ａ部分以外の導体パターン１１を覆うように形成されたソルダーレジスト１５に接着される。従って、導体パターン１１，１３の電気的導通箇所は、フレキシブルプリント配線基板５の＠ＰＥＥＫ１２によって樹脂封止される。
【００２０】
図３Ａは、フレキシブルプリント配線基板５の側面図、図３Ｂはフレキシブルプリント配線基板５を下方から見た場合の平面図を示している。図３Ａ，図３Ｂに示すように、導体パターン１３は、フレキシブルプリント配線基板５の長手方向に平行に延びる複数の配線を有し、その端部が接続端子としてのランド１３ａとして機能する。このランド１３ａを除いて、導体パターン１３は保護膜としてのソルダーレジスト１６によって被覆されている。
【００２１】
導体パターン１３のランド１３ａは、プリント配線基板５の接続面の先端部から所定距離離れた位置に形成されており、その結果、接続面先端部は、＠ＰＥＥＫ１２のみからなっている。また、複数の配線の内、両端に位置する配線も、＠ＰＥＥＫ１２の側端面から所定距離離れた位置に形成されており、＠ＰＥＥＫ１２が軟化変形する際に、確実に封止されるようになっている。
【００２２】
次に第１のプリント配線基板であるフレキシブルプリント配線基板５と第２のプリント配線基板であるリジッドプリント配線基板２の接続方法を図４を用いて説明する。
【００２３】
まず、図４Ａに示すように、リジッドプリント配線基板２の絶縁基板１０上に導体パターン１１を形成する。このとき、導体パターン１１は、リジッドプリント配線基板２の接続面先端部には形成されず、リジッドプリント配線基板２はその先端部においてガラスエポキシ樹脂１０が露出される。その後、リジッドプリント配線基板２の導体パターン１１の形成されていない端部、導体パターン１１のランド１１部分、及びランド１１間を除いて、ソルダーレジスト１５を形成し、導体パターン１１をソルダーレジスト１５によって被覆する。さらに、導体パターン１１のランド１１ａ部分には、半田ペースト１４が塗布される。なお、半田１４の形成に際しては、ランド１１ａ部分に半田メッキを施したり、半田コートを行ったりしても良い。本例では、半田１４として、錫−鉛の共晶半田を用いており、その融点（溶融温度）は１８３℃である。
【００２４】
半田１４には、その塗れ性を確保するため、フラックスや、アルカンのような炭化水素化合物が塗布される。特に、アルカン等の炭化水素化合物を塗布する場合には、半田１４のみでなく、両基板の重ね合わせ面全体にも塗布することが好ましい。この場合、リジッドプリント配線基板２とフレキシブルプリント配線基板５との間にアルカンを介在させた状態でアルカンの沸点以上に加熱を行うと、アルカンが＠ＰＥＥＫ１２の表面に入り込む。この結果、＠ＰＥＥＫ１２の表面には、アルカンが分散した分散層が形成される。この分散層は、＠ＰＥＥＫ１２が本来有する弾性率よりも低い弾性率を有する。すなわち、分散層をその表面に形成することにより、被接着層への密着性が強まり、＠ＰＥＥＫ１２の接着性を向上することができる。
【００２５】
そして、図４Ｂに示すように、フレキシブルプリント基板５に、リジッドプリント配線基板２上の導体パターン１１に対応するように、導体パターン１３を形成する。このときにも、導体パターン１３は、フレキシブルプリント配線基板５の接続面先端部には形成されない。そして、フレキシブルプリント配線基板５の先端部、導体パターン１３のランド１３ａ部分及びランド１３ａ間を除いて、ソルダーレジスト１６を形成する。このようにして形成されたフレキシブルプリント配線基板５をリジッドプリント配線基板２に対して位置合わせして重ねる。
【００２６】
次に、図４Ｃに示すように、リジッドプリント配線基板２とフレキシブルプリント配線基板５とを重ねた接続箇所を熱圧着ツール２１によって押圧しつつ、加熱する。このとき、＠ＰＥＥＫ１２のガラス転移温度は、１５０℃〜２３０℃であり、熱圧着ツール２１は、接続箇所が、半田１４の溶融温度以上でかつ＠ＰＥＥＫ１２のガラス転移温度以上の温度となるように加熱を行いつつ、当該部位に圧力を加える。例えば、加熱温度は２４０℃〜３００℃であり、５秒〜１５秒間加熱及び加圧を継続する。なお、本例では、パルスヒート方式の熱圧着ツール２１を用いている。
【００２７】
この加熱により、半田１４を溶融させて導体パターン１１，１３のランド１１ａ，１３ａ間の接続を行いながら、フレキシブルプリント配線基板５の絶縁基板を構成する＠ＰＥＥＫ１２を軟化変形させ、両基板の接続箇所におけるランド１１ａ，１３ａや導体パターン１１，１３を樹脂封止する。
【００２８】
ここで、本例では、フレキシブルプリント配線基板５の先端部に、導体パターン１３を形成しておらず、＠ＰＥＥＫ１２のみからなる部分を有している。この＠ＰＥＥＫ１２からなる先端部が、導体パターン１３を封止するための十分な樹脂を供給できる。
【００２９】
つまり、図１０に示すように、従来のフレキシブルプリント配線基板は、その端部まで導体パターンが形成されていたので、その端部において導体パターンが露出されるおそれがあり、別途、保護用絶縁フィルムを設ける等の構成を採用していた。
【００３０】
これに対し、本案では、フレキシブルプリント配線基板５の絶縁基板の材料として熱可塑性樹脂を使用し、その熱可塑性樹脂の流動性を利用して、接続箇所の樹脂封止を行うものであり、特にフレキシブルプリント配線基板５の先端部に＠ＰＥＥＫ１２のみからなる部分を設けているので、導体パターン１３が露出されることを確実に防止できる。
【００３１】
なお、フレキシブルプリント配線基板５の絶縁基板を構成している＠ＰＥＥＫ１２は、ガラス転移温度以上に加熱されると、軟化して変形するとともに、その軟化状態においてガラスエポキシ樹脂やソルダーレジストに強固に接着する。このため、従来、リジッドプリント配線基板とフレキシブルプリント配線基板の接続のために用いていた接着剤も、本例では省略可能である。
【００３２】
このように、本例では、基板自身の溶融性を利用し、端子接続と同時に樹脂封止を行うことができるので、製造コストの低減を図ることができる。また、フレキシブルプリント配線基板５の＠ＰＥＥＫ１２が軟化すると、リジッドプリント配線基板２とフレキシブルプリント配線基板５との間に存在する空気を押し退けながら、リジッドプリント配線基板２方向に流動する。このため、フィルム等を予め両基板の間に挟み込む場合に比べてボイドができにくく、接続箇所の信頼性を向上できる。
【００３３】
（第２の実施の形態）
次に、本発明の第２の実施の形態を図面に基づいて説明する。
【００３４】
第２の実施の形態によるリジッドプリント配線基板２とフレキシブルプリント配線基板１０５の接続方法及び接続構造は、第１の実施の形態によるものと共通するところが多いので、以下、共通部分については詳しい説明は省略し、異なる部分を重点的に説明する。
【００３５】
第２の実施の形態における、フレキシブルプリント配線基板１０５の構造として、図５，図６に示すように基板先端部にもソルダーレジスト１６ａを設けたことが、第１の実施の形態におけるフレキシブルプリント基板５に対して最も異なる点である。
【００３６】
ここで、リジッドプリント配線基板２上の導体パターン１１のランド１１ａに形成される半田１４の量が過剰である場合に、熱圧着ツール２１によってリジッドプリント配線基板２とフレキシブルプリント配線基板５との重ね合わせ部分が加圧・加熱されたとき、溶融された半田１４がフレキシブルプリント配線基板１０５の先端からはみ出すおそれがある。つまり、半田１４の量が過剰である場合には、半田１４が溶融されたときに、フレキシブルプリント配線基板５の導体パターン１３に沿って流動し、最悪の場合、フレキシブルプリント配線基板１０５の先端部からはみ出すのである。
【００３７】
このため、本例では、図５Ａ，図５Ｂに示すようにフレキシブルプリント配線基板１０５の接続面先端部に、ソルダーレジスト１６ａを設けた。このソルダーレジスト１６ａにより、過剰な量の半田１４が導体パターン１１のランド１１ａに与えられた場合でも、基板先端部に設けたソルダーレジスト１６ａが半田１４の流動をブロックする。このため、図６に示すように、フレキシブルプリント配線基板１０５とリジッドプリント配線基板２とが熱圧着ツール２１によって接合されたときに、半田１４がフレキシブルプリント配線基板１０５の先端部からはみ出すことを確実に防止し、接続箇所の絶縁性を確保することが可能である。
【００３８】
なお、図５に示す例では、銅からなる導体パターン１３をフレキシブルプリント配線基板１０５の先端部まで延在させ、その先端部の導体パターン１３を覆うようにソルダーレジスト１６ａを形成している。しかしながら、導体パターン１３が基板の先端部まで設けられている必要はなく、第１の実施形態と同様に、導体パターン１３を基板の先端部に到達する以前に終端させても良い。この場合には、フレキシブルプリント配線基板１０５の絶縁基板をなす＠ＰＥＥＫ１２の上に直接ソルダーレジスト１６ａを形成すれば良い。このようにすれば、＠ＰＥＥＫ１２の軟化変形時に導体パターン１３が外部に露出されるおそれがなくなるので、より好ましい。
【００３９】
また、ソルダーレジストは、接続面の先端部のみでなく、フレキシブルプリント配線基板１０５の長手方向に平行な両側端部に形成しても良い。これにより、あらゆる方向への半田のはみ出しを防止することが可能になる。
【００４０】
（第３の実施の形態）
次に、本発明の第３の実施の形態を図面に基づいて説明する。
【００４１】
第３の実施の形態によるリジッドプリント配線基板２とフレキシブルプリント配線基板２０５の接続方法及び接続構造も、第１の実施の形態によるものと共通するところが多いので、以下、共通部分については詳しい説明は省略し、異なる部分を重点的に説明する。
【００４２】
第３の実施の形態においては、図７Ａ，図７Ｂに示すように、フレキシブルプリント配線基板２０５のソルダーレジスト２１６の端部において、導体パターン１３を被覆し、隣接する導体パターン１３間の＠ＰＥＥＫ１２を露出するように、導体パターン１３に合わせて複数の凸状部分２１６ａを形成した点が、第１の実施の形態におけるフレキシブルプリント基板５に対して最も異なる点である。
【００４３】
ソルダーレジスト２１６は、例えば、変性エポキシ樹脂を主成分として、さらにフィラー、有機溶剤、硬化剤等を添加して構成されるものである。このソルダーレジスト２１６をフレキシブルプリント配線基板２０５上に設けた後に、加圧・加熱によりリジッドプリント配線基板２の絶縁基板１０の材料であるガラスエポキシ樹脂と接着しようとしても、両者とも熱硬化性の性質を有しているので、その接合強度は十分なものとは言えない。
【００４４】
このため、本例では、フレキシブルプリント配線基板２０５において、隣接する導体パターン１３間のソルダーレジストを除去してソルダーレジスト２１６の端部を凹凸状として、その凹状部分において熱可塑性樹脂である＠ＰＥＥＫ１２を露出させた。
【００４５】
図８に示すように、フレキシブルプリント配線基板２０５と接続されるリジッドプリント配線基板２は、その接続面先端部において、導体パターン１１もソルダーレジスト１５も形成されない領域を設けている。すなわち、フレキシブルプリント配線基板２０５との接続前は、その先端部の領域においては、リジッドプリント配線基板２の絶縁基板１０の材料であるガラスエポキシ樹脂が露出されている。
【００４６】
そして、上記のように、ソルダーレジスト２１６の凹状部分において露出された＠ＰＥＥＫ１２が、リジッドプリント配線基板２の先端部のガラスエポキシ樹脂１０に位置合わせされる。つまり、＠ＰＥＥＫ１２を露出させるソルダーレジスト２１６の凹部の先端は、リジッドプリント配線基板２の端面よりも内側に位置するように位置合わせされる。
【００４７】
この露出された＠ＰＥＥＫ１２は、熱圧着ツール２１によって接合箇所が加圧・加熱されたときに、軟化変形し、リジッドプリント基板２に向かって流動する。そして、この軟化した＠ＰＥＥＫ１２がリジッドプリント基板２のガラスエポキシ樹脂１０に密着することにより、両者が強固に接合される。
【００４８】
これにより、最も応力がかかるフレキシブルプリント基板２０５の接合箇所のヒール側の接合強度を向上させることが可能となる。さらに、フレキシブルプリント基板２０５の接合箇所のヒール側において、＠ＰＥＥＫ１２がリジッドプリント基板２の表面に達して、ガラスエポキシ樹脂１０と強固に接合されるので、接合箇所のヒール側の導体パターン１３の回りをガラスエポキシ樹脂１０と＠ＰＥＥＫ１２とが取り囲むことになる。これにより、接合箇所のヒール側の導体パターン１３の樹脂封止をより完全なものとすることができる。
【００４９】
以上、本発明の好ましい実施形態について説明したが、本発明は上述の実施形態のみに限定されず、種々変更して実施することができる。
【００５０】
例えば、上述の実施形態では、リジッドプリント配線基板とフレキシブルプリント配線基板との電気的接続において、フレキシブルプリント配線基板の基板材料の熱可塑性特性を利用して、端子間の半田による接続と同時に端子周辺の樹脂封止を同時に行うようにした。しかし、第１のプリント配線基板と第２のプリント配線基板との接続において、両方または、どちらか一方が熱可塑性樹脂を用いたフレキシブルプリント配線基板であれば良い。
【００５１】
また、リジッドプリント配線基板を用いる場合には、その絶縁基板として、
樹脂基板以外にもセラミック基板やメタルベース基板を用いても良い。
【００５２】
また、フレキシブルプリント配線基板の絶縁樹脂材料としては、上述の＠ＰＥＥＫ以外にも、ポリエーテルイミド（ＰＥＩ）もしくはポリエーテルエーテルケトン（ＰＥＥＫ）を単独で使用することも可能である。さらに、フレキシブルプリント配線基板の絶縁樹脂材料として、ポリエチレンナフタレート（ＰＥＮ）やポリエチレンテレフタレート（ＰＥＴ）を用いても良い。あるいは、フレキシブルプリント配線基板の絶縁基板として、ポリイミド基板に、ＰＥＥＫ，ＰＥＩ，ＰＥＮ，ＰＥＴの少なくともいずれかの熱可塑性樹脂材料からなる層を積層した構造のものを使用しても良い。なお、積層時には、例えば接着剤を用いてポリイミド基板と熱可塑性樹脂材料からなる層をと接着することができる。ポリイミド基板は熱膨張係数が１５〜２０ｐｐｍ程度で、配線として利用されることが多い銅の熱膨張係数と近いため（１７〜２０ｐｐｍ）、剥がれやフレキシブルプリント配線基板の反り等の発生を防止することができる。
【００５３】
また、上述の例では、半田１４をリジッドプリント配線基板２の導体パターン１１のランド１１ａに設けたが、フレキシブルプリント配線基板側の導体パターン１３のランド１３ａ上に設けても良い。また、両方のランド１１ａ，１３ａに半田を設けても良い。さらに、導電性接着剤を用いて両プリント配線基板のランド（端子）を接合しても良いし、ランド同士を直接接触させても良い。さらに、導体パターンにおけるランドの形状は、角ランド、丸ランド、異形ランドのいずれでも良い。
【００５４】
さらに、上述した第１及び第２実施例において、フレキシブルプリント配線基板５，１０５のソルダーレジスト１６、１６ａに代えて、前述した熱可塑性材料からなるカバーレイによって導体パターン１３を被覆しても良い。前述したように、変性エポキシ樹脂を主成分とするソルダーレジストは、リジッドプリント配線基板の基板材料であるエポキシ樹脂やその基板上に形成された同成分のソルダーレジストとの接合強度は十分ではない。しかしながら、フレキシブルプリント配線基板５，１０５の導体パターン１３を前述した熱可塑性材料（＠ＰＥＥＫ，ＰＥＥＫ，ＰＥＩ，ＰＥＮ，ＰＥＴ）からなるカバーレイで被覆することにより、このカバーレイがリジッドプリント配線基板の基板材料であるエポキシ樹脂や基板上に形成されるソルダーレジストと強固に密着し、両配線基板の接合強度を大幅に向上することができる。さらに、このカバーレイがリジッドプリント配線基板の先端部のエポキシ樹脂と密着することにより、両配線基板の電気的接続部の樹脂封止をより確実に行うことが可能になる。
【００５５】
また、リジッドプリント配線基板２の導体パターン１１上に形成されるソルダーレジスト１５を上述した熱可塑性樹脂からなるカバーレイとしても良い。
【図面の簡単な説明】
【図１】実施形態における電子機器の一部を示す斜視図である。
【図２】第１の実施形態における接続部分を示す断面図である。
【図３】フレキシブルプリント配線基板の側面図及び平面図である。
【図４】製造方法を説明するための断面図である。
【図５】第２の実施形態におけるフレキシブルプリント配線基板の側面図及び平面図である。
【図６】第２の実施形態における接続部分を示す断面図である。
【図７】第３の実施形態におけるフレキシブルプリント配線基板の側面図及び平面図である。
【図８】第３の実施形態における接続部分を示す断面図である。
【図９】従来技術を説明するための断面図である。
【図１０】従来技術を説明するための断面図である。
【符号の説明】
２…リジッドプリント配線基板、５…フレキシブルプリント配線基板、１１導体パターン、１１ａ…ランド、１３…導体パターン、１３ａ…ランド，１４…半田、１５…ソルダーレジスト、１６…ソルダーレジスト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connection method and a connection structure of a printed wiring board.
[0002]
[Prior art]
Conventionally, as a connection structure of a printed wiring board, one using an anisotropic conductive resin material is known (Japanese Patent Laid-Open No. 9-8453). As shown in FIG. 9, the anisotropic conductive thermoplastic resin 52 is placed between the conductor pattern forming surface of the first printed wiring board 50 and the conductor pattern forming surface of the second printed wiring board 51. The thermoplastic resin 52 is melted by pressure and ultrasonic waves. As a result, the distance between the lands 50a and 50b is narrowed and the two are electrically connected.
[0003]
Further, on page 100 of “Introduction to High Density Flexible Board” (published by Kenji Numakura, published by Nikkan Kogyo Shimbun), a method for connecting a hard printed board and a flexible board by thermal soldering is shown. According to this connection method, as shown in FIG. 10, the land 60 a of the conductor pattern of the hard printed circuit board 60 and the land 61 a of the conductor pattern of the flexible board 61 are connected by the solder 62. Further, the flexible substrate 61 is bonded to the hard printed circuit board 60 via the adhesive 63.
[0004]
[Problems to be solved by the invention]
However, in the connection structure shown in FIG. 9, the anisotropic conductive resin film must be printed on the surface of the printed wiring boards 50 and 51, or the anisotropic conductive resin film must be placed on the surfaces of the printed wiring boards 50 and 51. Don't be. For this reason, the process for obtaining a connection structure increases and becomes a factor of manufacturing cost increase. Further, since the surfaces of the printed wiring boards 50 and 51 are connected to face each other with the anisotropic conductive resin material 52 interposed, voids are generated at the bonding interface between the resin material 52 and the printed wiring boards 50 and 51. It is easy to do and is inferior in reliability.
[0005]
Further, in the connection structure shown in FIG. 10, it is necessary to cover the end portion of the flexible substrate 61 with a protective insulating film or the like after the connection of the flexible substrate 61 in order to ensure the insulation reliability of the connection portion. There is a problem that increases.
[0006]
The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a printed wiring board connection method and a connection structure capable of improving connection reliability and reducing manufacturing costs. .
[0007]
[Means for Solving the Problems]
  In the connection method of the printed wiring board according to claim 1, the land as the connection terminal is provided in a region excluding the front end portion of the connection surface in the connection surface of the first printed wiring board using the thermoplastic resin as the insulating substrate material. Forming a conductive pattern including:
  A land of a conductor pattern formed on the connection surface of the first printed wiring board in a state where the front end portion of the connection surface of the first printed wiring board is disposed on the connection surface of the second printed wiring board; A step of overlapping and arranging the land of the conductor pattern formed on the connection surface of the wiring board;
  While heating the connection part of the said 1st printed wiring board and the said 2nd printed wiring board more than the glass transition temperature of the said thermoplastic resin, a pressure is applied to the said site | part, The land and the land of the second printed wiring board are electrically connected, the thermoplastic resin constituting the first printed wiring board is softened and deformed, and the thermoplastic resin at the tip of the connection surface is And a step of closely contacting the connection surface of the printed wiring board with a thermoplastic resin at the connection location.,
  The thermoplastic resin consists of a single layer containing 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin.The
[0008]
Thus, without using an anisotropic conductive film or the like, the deformability due to the change of the first printed wiring board itself can be used, and the connection location can be resin-sealed together with the terminal connection, thus reducing the manufacturing cost. You can plan. In addition, a region where no conductor pattern is formed is provided at the front end of the connection surface of the first printed wiring board, and the front end of the connection surface is brought into close contact with the connection surface of the second printed wiring board. The conductor pattern can be sealed.
[0009]
  Moreover, the connection method of the printed wiring board of Claim 7 is used as an insulating board material.A monolayer comprising 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin.Forming a conductor pattern including a land as a connection terminal on the connection surface of the first printed wiring board using a thermoplastic resin;
  Excluding the land of the conductor pattern, covering the conductor pattern with a protective film, and forming the protective film also in the vicinity of the connection surface end of the first printed wiring board;
  Arranging the conductor pattern lands formed on the first printed wiring board and the conductor pattern lands formed on the connection surface of the second printed wiring board in an overlapping manner via a connecting material;
  While heating the connection part of the said 1st printed wiring board and the said 2nd printed wiring board more than the glass transition temperature of the said thermoplastic resin, a pressure is applied to the said site | part, The land and the land of the second printed wiring board are electrically connected via the connecting material, and the thermoplastic resin constituting the first printed wiring board is softened and deformed, so that a conductor pattern at the connection location is obtained. A step of sealing with a thermoplastic resin,
  The protective film formed at the end of the connection surface of the first printed wiring board blocks the flow of the connection material to the outside of the connection surface.
[0010]
As a result, even if the amount of the connecting material between the lands of the first and second printed wiring boards is excessive and flows when the two printed wiring boards are connected, they are formed at the end of the connecting surface of the first printed wiring board. In addition, since the protective film blocks the flow, the insulation reliability at the connection location can be improved.
[0011]
  Furthermore, the connection method of the printed wiring board of Claim 14 forms the conductor pattern containing the land as a connection terminal in the connection surface of the 1st printed wiring board using the thermoplastic resin as an insulating board material. When,
  When the conductor pattern is covered with a protective film except for the land of the conductor pattern, the surface of the first printed wiring board on both sides thereof is exposed while covering the conductor pattern at the end of the protective film. Forming a convex portion so as to allow,
  A conductor pattern including lands as connection terminals is formed on the second printed wiring board so that the end of the conductor pattern terminates at a position away from the front end of the connection surface of the second printed wiring board by a predetermined distance. Process,
  The conductor pattern land formed on the first printed wiring board and the conductor pattern land formed on the connection surface of the second printed wiring board are overlapped, and the exposed surface of the first printed wiring board is A step of arranging the second printed wiring board so as to face the front end of the connection surface;
  While heating the connection part of the said 1st printed wiring board and the said 2nd printed wiring board more than the glass transition temperature of the said thermoplastic resin, a pressure is applied to the said site | part, The land and the land of the second printed wiring board are electrically connected via the connecting material, and the thermoplastic resin constituting the first printed wiring board is softened and deformed, and is exposed from the protective film. The thermoplastic resin of the first printed wiring board in the part is closely attached to the front end of the connection surface of the second printed wiring board and the conductor pattern at the connection location is sealed with the thermoplastic resin, On the connection surface of the printed circuit board 1, the conductor pattern is formed to terminate at a position away from the connection surface tip by a predetermined distance. Thermoplastic resin, in close contact with the connection surface of the second printed circuit board,
  The thermoplastic resin consists of a single layer containing 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin.It is characterized by that.
[0012]
Thereby, the adhesive strength in the front-end | tip part of the 2nd printed wiring board where stress is most stressed in the connection location of a 1st printed wiring board and a 2nd printed wiring board can be improved. Further, since the conductor pattern of the first printed wiring board located at the tip of the second printed wiring board is sealed so as to be surrounded by the thermoplastic resin and the second printed wiring board, the resin sealing is performed. Reliability can be improved.
[0013]
  Claim 17, 23, 30The printed circuit board connection structure described in 1 is obtained by the printed circuit board connection method according to the first, seventh, and 14th aspects, respectively, and the effects thereof are substantially the same as those described above.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
[0015]
FIG. 1 shows a part of the electronic apparatus according to the first embodiment. A rigid printed wiring board 1 and a rigid printed wiring board 2 are supported inside the electronic device. Various electronic components are mounted on the rigid printed wiring board 1, and FIG. 1 shows a state in which the IC 3 of the DIP package is mounted via the pins 3a. Similarly, various electronic components 4 are also mounted on the rigid printed wiring board 2. As a material of the insulating substrate 10 of these rigid printed wiring boards 1 and 2, for example, a glass cloth base epoxy resin can be used.
[0016]
A flexible printed wiring board 5 is connected between the respective end portions of the rigid printed wiring board 1 and the rigid printed wiring board 2 that are horizontally arranged in the vertical direction, and the two are electrically connected. As a material of the insulating substrate 12 of the flexible printed circuit board 5, a thermoplastic resin (@PEEK) containing 65 to 35% by weight of polyetheretherketone (PEEK) resin and 35 to 65% by weight of polyetherimide (PEI) resin. Is used. This @PEEK is a thermoplastic resin that softens at a temperature above the glass transition temperature.
[0017]
FIG. 2 is an enlarged view of a connection portion between the rigid printed wiring board 2 and the flexible printed wiring board 5.
[0018]
A plurality of conductor patterns 11 are formed on the upper surface of the rigid printed wiring board 2, and lands 11 a are formed at the ends of the conductor patterns 11 that terminate at a predetermined distance from the end of the board. On this land 11a, solder 14 is applied as a connection material. A plurality of conductor patterns 13 are also formed on the surface of the flexible printed circuit board 5 in correspondence with the conductor patterns 11 on the rigid printed circuit board 2, and lands 13a as connection terminals are formed at their ends. Yes. These conductor patterns 11 and 13 are made of copper.
[0019]
The glass epoxy resin which comprises the rigid printed wiring board 2 while the land 11a of the conductor pattern 11 and the land 13a of the conductive pattern 13 are connected by the solder 14 in the connection location of the rigid printed wiring board 2 and the flexible printed wiring board 5. 10 and @PEEK 12 constituting the flexible printed circuit board 5 are bonded between the conductor patterns 11 and 13 by deformation of @PEEK 12. Further, the glass epoxy resin 10 at the end of the rigid printed wiring board 2 is bonded to a solder resist 16 formed on the flexible printed wiring board 5 so as to cover the conductor pattern 13 other than the land 13a portion. The @PEEK 12 at the end of the flexible printed circuit board 5 is adhered to a solder resist 15 formed on the rigid printed circuit board 2 so as to cover the conductor pattern 11 other than the land 11a portion. Therefore, the electrically conductive portions of the conductor patterns 11 and 13 are resin-sealed by @PEEK 12 of the flexible printed wiring board 5.
[0020]
3A is a side view of the flexible printed wiring board 5, and FIG. 3B is a plan view of the flexible printed wiring board 5 as viewed from below. As shown in FIGS. 3A and 3B, the conductor pattern 13 has a plurality of wirings extending in parallel with the longitudinal direction of the flexible printed wiring board 5, and its end functions as a land 13a as a connection terminal. Except for the land 13a, the conductor pattern 13 is covered with a solder resist 16 as a protective film.
[0021]
The land 13a of the conductor pattern 13 is formed at a position away from the front end of the connection surface of the printed wiring board 5 by a predetermined distance. As a result, the front end of the connection surface is made only of @ PEEK12. In addition, among the plurality of wirings, the wirings located at both ends are also formed at a predetermined distance from the side end surface of @PEEK 12, and when @PEEK 12 is softened and deformed, it is surely sealed. ing.
[0022]
Next, a method of connecting the flexible printed wiring board 5 as the first printed wiring board and the rigid printed wiring board 2 as the second printed wiring board will be described with reference to FIG.
[0023]
First, as shown in FIG. 4A, the conductor pattern 11 is formed on the insulating substrate 10 of the rigid printed wiring board 2. At this time, the conductive pattern 11 is not formed at the front end portion of the connection surface of the rigid printed wiring board 2, and the glass epoxy resin 10 is exposed at the front end portion of the rigid printed wiring board 2. Thereafter, a solder resist 15 is formed except for the end of the rigid printed wiring board 2 where the conductor pattern 11 is not formed, the land 11 portion of the conductor pattern 11, and the land 11, and the conductor pattern 11 is formed by the solder resist 15. Cover. Further, a solder paste 14 is applied to the land 11 a portion of the conductor pattern 11. When the solder 14 is formed, the land 11a may be subjected to solder plating or solder coating. In this example, tin-lead eutectic solder is used as the solder 14, and its melting point (melting temperature) is 183 ° C.
[0024]
The solder 14 is coated with a flux or a hydrocarbon compound such as alkane in order to ensure the paintability. In particular, when applying a hydrocarbon compound such as alkane, it is preferable to apply not only to the solder 14 but also to the entire overlapping surface of both substrates. In this case, when the alkane is heated above the boiling point of the alkane with the alkane interposed between the rigid printed wiring board 2 and the flexible printed wiring board 5, the alkane enters the surface of the @PEEK 12. As a result, a dispersed layer in which alkane is dispersed is formed on the surface of @ PEEK12. This dispersion layer has an elastic modulus lower than that inherent in @ PEEK12. That is, by forming the dispersion layer on the surface, the adhesion to the adherend layer is strengthened, and the adhesion of @PEEK 12 can be improved.
[0025]
4B, a conductor pattern 13 is formed on the flexible printed circuit board 5 so as to correspond to the conductor pattern 11 on the rigid printed circuit board 2. As shown in FIG. Also at this time, the conductor pattern 13 is not formed at the tip of the connection surface of the flexible printed wiring board 5. Then, a solder resist 16 is formed except for the tip of the flexible printed circuit board 5, the land 13a portion of the conductor pattern 13, and the land 13a. The flexible printed wiring board 5 formed in this way is aligned and overlapped with the rigid printed wiring board 2.
[0026]
Next, as shown in FIG. 4C, the connection portion where the rigid printed wiring board 2 and the flexible printed wiring board 5 are overlapped is heated while being pressed by the thermocompression bonding tool 21. At this time, the glass transition temperature of @ PEEK12 is 150 ° C. to 230 ° C., and the thermocompression bonding tool 21 is such that the connection location is not less than the melting temperature of solder 14 and not less than the glass transition temperature of @ PEEK12. Pressure is applied to the site while heating. For example, the heating temperature is 240 ° C. to 300 ° C., and heating and pressurization are continued for 5 to 15 seconds. In this example, a pulse heat type thermocompression bonding tool 21 is used.
[0027]
By this heating, the solder 14 is melted and the lands 11a and 13a of the conductor patterns 11 and 13 are connected to each other, and the @PEEK 12 constituting the insulating substrate of the flexible printed wiring board 5 is softened and deformed to connect the two substrates. The lands 11a and 13a and the conductor patterns 11 and 13 are sealed with resin.
[0028]
Here, in this example, the conductive pattern 13 is not formed at the tip of the flexible printed wiring board 5, and there is a portion consisting only of @PEEK 12. The tip portion made of @PEEK 12 can supply sufficient resin for sealing the conductor pattern 13.
[0029]
That is, as shown in FIG. 10, since the conventional flexible printed wiring board has a conductor pattern formed up to its end portion, the conductor pattern may be exposed at the end portion. The configuration such as providing the was adopted.
[0030]
On the other hand, in this proposal, a thermoplastic resin is used as the material of the insulating substrate of the flexible printed circuit board 5, and the resin sealing of the connection portion is performed using the fluidity of the thermoplastic resin. Since the part which consists only of @ PEEK12 is provided in the front-end | tip part of the flexible printed wiring board 5, it can prevent reliably that the conductor pattern 13 is exposed.
[0031]
In addition, @ PEEK12 constituting the insulating substrate of the flexible printed circuit board 5 softens and deforms when heated to a temperature higher than the glass transition temperature, and adheres firmly to the glass epoxy resin or solder resist in the softened state. To do. For this reason, the adhesive agent conventionally used for connection of a rigid printed wiring board and a flexible printed wiring board can also be abbreviate | omitted in this example.
[0032]
Thus, in this example, since the resin sealing can be performed simultaneously with the terminal connection using the meltability of the substrate itself, the manufacturing cost can be reduced. Further, when @PEEK 12 of the flexible printed wiring board 5 is softened, the air flows between the rigid printed wiring board 2 and the flexible printed wiring board 5 and flows in the direction of the rigid printed wiring board 2. For this reason, compared with the case where a film etc. are previously pinched | interposed between both board | substrates, a void is hard to be formed and the reliability of a connection location can be improved.
[0033]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.
[0034]
Since the connection method and connection structure between the rigid printed wiring board 2 and the flexible printed wiring board 105 according to the second embodiment are often the same as those according to the first embodiment, a detailed description of the common parts will be given below. Omitted and focused on the differences.
[0035]
As the structure of the flexible printed wiring board 105 in the second embodiment, as shown in FIGS. 5 and 6, the solder resist 16 a is also provided at the front end of the board, which is the flexible printed board in the first embodiment. 5 is the most different point.
[0036]
Here, when the amount of the solder 14 formed on the land 11 a of the conductor pattern 11 on the rigid printed wiring board 2 is excessive, the rigid printed wiring board 2 and the flexible printed wiring board 5 are overlapped by the thermocompression bonding tool 21. When the mating portion is pressed and heated, the molten solder 14 may protrude from the tip of the flexible printed wiring board 105. That is, when the amount of the solder 14 is excessive, when the solder 14 is melted, it flows along the conductor pattern 13 of the flexible printed wiring board 5, and in the worst case, the tip of the flexible printed wiring board 105. It sticks out.
[0037]
For this reason, in this example, as shown in FIGS. 5A and 5B, a solder resist 16a is provided at the tip of the connection surface of the flexible printed wiring board 105. FIG. Even when an excessive amount of solder 14 is applied to the land 11a of the conductor pattern 11 by the solder resist 16a, the solder resist 16a provided at the front end of the substrate blocks the flow of the solder 14. For this reason, as shown in FIG. 6, when the flexible printed circuit board 105 and the rigid printed circuit board 2 are joined by the thermocompression bonding tool 21, it is ensured that the solder 14 protrudes from the front end portion of the flexible printed circuit board 105. It is possible to prevent this, and to ensure the insulation of the connection part.
[0038]
In the example shown in FIG. 5, the conductor pattern 13 made of copper is extended to the tip of the flexible printed circuit board 105, and the solder resist 16a is formed so as to cover the conductor pattern 13 at the tip. However, the conductor pattern 13 does not have to be provided up to the tip of the substrate, and the conductor pattern 13 may be terminated before reaching the tip of the substrate, as in the first embodiment. In this case, the solder resist 16a may be formed directly on the @PEEK 12 that forms the insulating substrate of the flexible printed wiring board 105. This is more preferable because there is no possibility that the conductor pattern 13 is exposed to the outside when the @PEEK 12 is softened and deformed.
[0039]
Further, the solder resist may be formed not only at the front end portion of the connection surface but also at both side end portions parallel to the longitudinal direction of the flexible printed wiring board 105. This makes it possible to prevent the solder from protruding in any direction.
[0040]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings.
[0041]
Since the connection method and connection structure between the rigid printed wiring board 2 and the flexible printed wiring board 205 according to the third embodiment are also common to those according to the first embodiment, a detailed description of the common parts will be given below. Omitted and focused on the differences.
[0042]
In the third embodiment, as shown in FIGS. 7A and 7B, the conductive pattern 13 is covered at the end of the solder resist 216 of the flexible printed wiring board 205, and the @PEEK 12 between the adjacent conductive patterns 13 is set. The most different point from the flexible printed circuit board 5 in the first embodiment is that a plurality of convex portions 216a are formed in conformity with the conductor pattern 13 so as to be exposed.
[0043]
The solder resist 216 is configured by, for example, using a modified epoxy resin as a main component and further adding a filler, an organic solvent, a curing agent, and the like. Even if the solder resist 216 is provided on the flexible printed wiring board 205 and then is applied to the glass epoxy resin which is the material of the insulating substrate 10 of the rigid printed wiring board 2 by pressing and heating, both of them are thermosetting properties. Therefore, it cannot be said that the bonding strength is sufficient.
[0044]
Therefore, in this example, in the flexible printed wiring board 205, the solder resist between the adjacent conductor patterns 13 is removed to make the end portion of the solder resist 216 uneven, and @ PEEK12 which is a thermoplastic resin is used in the concave portion. Exposed.
[0045]
As shown in FIG. 8, the rigid printed wiring board 2 connected to the flexible printed wiring board 205 is provided with a region where neither the conductive pattern 11 nor the solder resist 15 is formed at the tip of the connecting surface. That is, before the connection with the flexible printed circuit board 205, the glass epoxy resin that is the material of the insulating substrate 10 of the rigid printed circuit board 2 is exposed in the region of the tip portion.
[0046]
Then, as described above, the @PEEK 12 exposed in the concave portion of the solder resist 216 is aligned with the glass epoxy resin 10 at the distal end portion of the rigid printed wiring board 2. That is, the tip of the concave portion of the solder resist 216 exposing the @PEEK 12 is aligned so as to be located inside the end face of the rigid printed wiring board 2.
[0047]
The exposed @PEEK 12 is softened and deformed and flows toward the rigid printed circuit board 2 when the joining portion is pressurized and heated by the thermocompression bonding tool 21. Then, the softened @PEEK 12 comes into close contact with the glass epoxy resin 10 of the rigid printed circuit board 2 so that both are firmly joined.
[0048]
As a result, it is possible to improve the joint strength on the heel side of the joint portion of the flexible printed circuit board 205 that is most stressed. Further, at the heel side of the joint portion of the flexible printed board 205, @PEEK 12 reaches the surface of the rigid printed board 2 and is firmly joined to the glass epoxy resin 10. Therefore, around the conductive pattern 13 on the heel side of the joint portion. Is surrounded by the glass epoxy resin 10 and @ PEEK12. Thereby, the resin sealing of the conductor pattern 13 on the heel side of the joint portion can be made more complete.
[0049]
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, It can implement in various changes.
[0050]
For example, in the above-described embodiment, in the electrical connection between the rigid printed wiring board and the flexible printed wiring board, by utilizing the thermoplastic property of the substrate material of the flexible printed wiring board, the connection between the terminals and the periphery of the terminals simultaneously The resin sealing was performed at the same time. However, in the connection between the first printed wiring board and the second printed wiring board, both or one of them may be a flexible printed wiring board using a thermoplastic resin.
[0051]
In addition, when using a rigid printed circuit board, as its insulating substrate,
In addition to the resin substrate, a ceramic substrate or a metal base substrate may be used.
[0052]
Further, as the insulating resin material for the flexible printed circuit board, polyetherimide (PEI) or polyetheretherketone (PEEK) can be used alone in addition to the above-mentioned @PEEK. Furthermore, polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) may be used as an insulating resin material for the flexible printed circuit board. Or you may use the thing of the structure which laminated | stacked the layer which consists of at least any one of PEEK, PEI, PEN, and PET on a polyimide substrate as an insulated substrate of a flexible printed wiring board. In addition, at the time of lamination | stacking, the layer which consists of a polyimide substrate and a thermoplastic resin material can be adhere | attached, for example using an adhesive agent. The polyimide substrate has a thermal expansion coefficient of about 15-20 ppm, which is close to the thermal expansion coefficient of copper that is often used as wiring (17-20 ppm), and therefore prevents the occurrence of peeling or warping of the flexible printed wiring board. Can do.
[0053]
In the above example, the solder 14 is provided on the land 11a of the conductor pattern 11 of the rigid printed wiring board 2. However, the solder 14 may be provided on the land 13a of the conductive pattern 13 on the flexible printed wiring board side. Also, solder may be provided on both lands 11a and 13a. Furthermore, the lands (terminals) of both printed wiring boards may be joined using a conductive adhesive, or the lands may be brought into direct contact with each other. Further, the land shape in the conductor pattern may be any of a square land, a round land, and a deformed land.
[0054]
Furthermore, in the first and second embodiments described above, the conductor pattern 13 may be covered with a cover lay made of the thermoplastic material described above, instead of the solder resists 16 and 16a of the flexible printed wiring boards 5 and 105. As described above, the solder resist mainly composed of the modified epoxy resin does not have sufficient bonding strength with the epoxy resin which is the substrate material of the rigid printed wiring board and the solder resist of the same component formed on the substrate. However, by covering the conductive pattern 13 of the flexible printed wiring boards 5 and 105 with a cover lay made of the thermoplastic material (@PEEK, PEEK, PEI, PEN, PET) described above, the cover lay is formed on the rigid printed wiring board. It is possible to greatly improve the bonding strength between the two wiring boards by firmly adhering to the epoxy resin as a substrate material or a solder resist formed on the substrate. Furthermore, since this cover lay is in close contact with the epoxy resin at the tip of the rigid printed wiring board, it becomes possible to more reliably perform resin sealing of the electrical connection portions of both wiring boards.
[0055]
Further, the solder resist 15 formed on the conductor pattern 11 of the rigid printed wiring board 2 may be a cover lay made of the above-described thermoplastic resin.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a part of an electronic apparatus according to an embodiment.
FIG. 2 is a cross-sectional view showing a connection portion in the first embodiment.
FIG. 3 is a side view and a plan view of a flexible printed wiring board.
FIG. 4 is a cross-sectional view for explaining a manufacturing method.
FIGS. 5A and 5B are a side view and a plan view of a flexible printed wiring board according to a second embodiment. FIGS.
FIG. 6 is a cross-sectional view showing a connection portion in the second embodiment.
FIGS. 7A and 7B are a side view and a plan view of a flexible printed wiring board according to a third embodiment. FIGS.
FIG. 8 is a cross-sectional view showing a connection portion in a third embodiment.
FIG. 9 is a cross-sectional view for explaining the prior art.
FIG. 10 is a cross-sectional view for explaining the prior art.
[Explanation of symbols]
2 ... Rigid printed wiring board, 5 ... Flexible printed wiring board, 11 conductor pattern, 11a ... Land, 13 ... Conductor pattern, 13a ... Land, 14 ... Solder, 15 ... Solder resist, 16 ... Solder resist

Claims

Forming a conductor pattern including a land as a connection terminal in a region excluding the front end of the connection surface in the connection surface of the first printed wiring board using a thermoplastic resin as an insulating substrate material;
A land of a conductor pattern formed on the connection surface of the first printed wiring board in a state where the front end portion of the connection surface of the first printed wiring board is disposed on the connection surface of the second printed wiring board; A step of overlapping and arranging the land of the conductor pattern formed on the connection surface of the wiring board;
While heating the connection part of the said 1st printed wiring board and the said 2nd printed wiring board more than the glass transition temperature of the said thermoplastic resin, a pressure is applied to the said site | part, The land and the land of the second printed wiring board are electrically connected, the thermoplastic resin constituting the first printed wiring board is softened and deformed, and the thermoplastic resin at the tip of the connection surface is And a step of closely contacting the connection surface of the printed wiring board of 2 and sealing the conductor pattern at the connection location with a thermoplastic resin ,
The method for connecting a printed wiring board, wherein the thermoplastic resin comprises a single layer containing 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin .

A protective film is formed on the conductor pattern of the first printed wiring board except for the lands, and a protective film is also formed on the conductor pattern of the second printed wiring board except for the lands. The printed wiring board connection method according to claim 1, wherein:

3. The connection of a printed wiring board according to claim 2, wherein a front end portion of the connection surface of the first printed wiring board is in close contact with a protective film formed on a conductor pattern of the second printed wiring board. Method.

The conductor pattern on the second printed circuit board is formed such that the conductor pattern terminates at a position away from the connection surface tip by a predetermined distance, and the connection surface tip on which the conductor pattern is not formed 4. The printed wiring board connection method according to claim 2, wherein the printed wiring board is in close contact with a protective film formed on the conductor pattern of the first printed wiring board.

The method for connecting a printed wiring board according to claim 2, wherein the protective film formed on the conductor pattern of the first printed wiring board is formed of a thermoplastic resin material.

6. The printed wiring board connection according to claim 1, wherein the conductor patterns of the first and second printed wiring boards each have a plurality of wirings and lands connected to the wirings. Method.

As a connection terminal on the connection surface of the first printed wiring board using a single layer thermoplastic resin containing 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin as an insulating substrate material Forming a conductor pattern including a land of
Excluding the land of the conductor pattern, covering the conductor pattern with a protective film, and forming the protective film also in the vicinity of the connection surface end of the first printed wiring board;
Arranging the conductor pattern lands formed on the first printed wiring board and the conductor pattern lands formed on the connection surface of the second printed wiring board in an overlapping manner via a connecting material;
While heating the connection part of the said 1st printed wiring board and the said 2nd printed wiring board more than the glass transition temperature of the said thermoplastic resin, a pressure is applied to the said site | part, The land and the land of the second printed wiring board are electrically connected via the connecting material, and the thermoplastic resin constituting the first printed wiring board is softened and deformed, so that a conductor pattern at the connection location is obtained. A step of sealing with a thermoplastic resin,
A method of connecting a printed wiring board, wherein a protective film formed on an end portion of the connection surface of the first printed wiring board blocks the flow of the connection material to the outside of the connection surface.

8. The printed wiring according to claim 7, wherein the thermoplastic resin at the end portion of the connection surface of the first printed wiring board is softened and deformed so as to cover a protective film formed in the vicinity of the end portion of the connection surface. Board connection method.

9. The printed wiring board connection method according to claim 7, wherein a protective film is also formed on the conductor pattern of the second printed wiring board except for the land.

When the thermoplastic resin at the end of the connection surface of the first printed wiring board is softened and deformed so as to cover the protective film, the softened and deformed thermoplastic resin becomes a conductor pattern of the second printed wiring board. The printed wiring board connection method according to claim 9, wherein the printed circuit board is in close contact with the protective film formed thereon.

The conductor pattern on the second printed wiring board is formed such that the conductor pattern terminates at a position away from the connection surface tip by a predetermined distance, and the connection surface tip not formed with the conductor pattern 11. The printed wiring board connection method according to claim 7, wherein the printed wiring board is in close contact with a protective film formed on the conductor pattern of the first printed wiring board.

The method for connecting a printed wiring board according to claim 7, wherein the protective film formed on the conductor pattern of the first printed wiring board is formed of a thermoplastic resin material.

13. The printed wiring board connection according to claim 7, wherein the conductor patterns of the first and second printed wiring boards each have a plurality of wirings and lands connected to the wirings. Method.

Forming a conductor pattern including lands as connection terminals on the connection surface of the first printed wiring board using a thermoplastic resin as an insulating substrate material;
When the conductor pattern is covered with a protective film except for the land of the conductor pattern, the surface of the first printed wiring board on both sides thereof is exposed while covering the conductor pattern at the end of the protective film. Forming a convex portion so as to allow,
A conductor pattern including lands as connection terminals is formed on the second printed wiring board so that the end of the conductor pattern terminates at a position away from the front end of the connection surface of the second printed wiring board by a predetermined distance. Process,
The conductor pattern land formed on the first printed wiring board and the conductor pattern land formed on the connection surface of the second printed wiring board are overlapped, and the exposed surface of the first printed wiring board is A step of arranging the second printed wiring board so as to face the front end of the connection surface;
While heating the connection part of the said 1st printed wiring board and the said 2nd printed wiring board more than the glass transition temperature of the said thermoplastic resin, a pressure is applied to the said site | part, The land and the land of the second printed wiring board are electrically connected via the connecting material, and the thermoplastic resin constituting the first printed wiring board is softened and deformed, and is exposed from the protective film. The thermoplastic resin of the first printed wiring board in the portion is closely attached to the connection surface tip of the second printed wiring board and the conductor pattern at the connection location is sealed with the thermoplastic resin,
In the connection surface of the first printed wiring board, the conductor pattern is formed so as to terminate at a position away from the connection surface tip portion by a predetermined distance, and the thermoplastic resin at the connection surface tip portion is the second surface. in close contact of the connecting surface of the printed wiring board,
The method for connecting a printed wiring board, wherein the thermoplastic resin comprises a single layer containing 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin .

15. The method for connecting printed wiring boards according to claim 14, wherein a protective film is also formed on the conductor pattern of the second printed wiring board except for the lands.

16. The printed wiring board connection method according to claim 14, wherein the conductor patterns of the first and second printed wiring boards each have a plurality of wirings and lands connected to the wirings.

The conductor pattern land formed on the connection surface of the first printed wiring board using thermoplastic resin as the insulating substrate material is electrically connected to the land of the conductor pattern formed on the connection surface of the second printed wiring board. Printed wiring board connection structure,
A conductor pattern at a connection portion between the first printed wiring board and the second printed wiring board is sealed with a thermoplastic resin constituting the first printed wiring board, and the first printed wiring board is sealed. The board has a region where the conductor pattern is not formed at the tip of the connection surface, and the thermoplastic resin in the region is in close contact with the connection surface of the second printed wiring board,
The thermoplastic resin, the connection structure of the print wiring board, characterized in that a single layer of a polyether ether ketone resin containing 65 to 35 wt% and a polyetherimide resin 35-65 wt%.

A protective film is formed on the conductor pattern of the first printed wiring board except for the lands, and a protective film is also formed on the conductor pattern of the second printed wiring board except for the lands. which do connection structure of a printed wiring board of claim 17 wherein Rukoto.

Connection surface tip portion of the first printed circuit board, the connection of the printed wiring board according to claim 18, in close contact with the protective film formed on the conductor pattern of the second printed circuit board, characterized in Rukoto Construction.

The conductor pattern on the second printed circuit board is formed such that the conductor pattern terminates at a position away from the connection surface tip by a predetermined distance, and the connection surface tip not formed with the conductor pattern is 20. The printed wiring board connection structure according to claim 18 , wherein the printed wiring board connection structure is in close contact with a protective film formed on the conductor pattern of the first printed wiring board.

It said first printed circuit board protective film formed on the conductive pattern of the connection structure of a printed wiring board according to any one of claims 17 to 20, characterized in that it is formed from a thermoplastic resin material.

Conductor patterns of the first and second printed circuit board, each of the plurality of wires and the printed circuit according to any one of claims 1 7 to 21, characterized in Rukoto that have a connected land that wire Board connection structure.

Conductor pattern formed on the connecting surface of the first printed wiring board using a single layer thermoplastic resin containing 65 to 35% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide resin as an insulating substrate material And a printed circuit board connection structure in which the land of the conductor pattern formed on the connection surface of the second printed circuit board is electrically connected,
The lands of the first and second printed wiring boards are electrically connected via a connecting material, and a conductor at a connection point between the first printed wiring board and the second printed wiring board. The pattern is sealed with a thermoplastic resin constituting the first printed wiring board, and the first printed wiring board has a protective film in the vicinity of the end of the connection surface, and the protective film is connection structure print wiring board, which comprises interrupting the flow of the connecting surface outside the connecting material.

Said first printed thermoplastic resin of the wiring connection surface edge portion of the substrate is a printed circuit according to claim 23, characterized in Rukoto softened deformed so as to cover the protective film formed on the connecting surface end Board connection structure.

Wherein also on the conductor pattern of the second printed wiring board, the connection structure of a printed wiring board according to claim 23 or 24, characterized in that the protective film except the land is formed.

When the thermoplastic resin at the end of the connection surface of the first printed wiring board is softened and deformed so as to cover the protective film, the softened and deformed thermoplastic resin becomes a conductor pattern of the second printed wiring board. connection structure of a printed wiring board according to claim 2 5, wherein the is bonded to the protective film formed thereon.

The conductor pattern on the second printed wiring board is formed such that the conductor pattern terminates at a position away from the connection surface tip by a predetermined distance, and the connection surface tip not formed with the conductor pattern 27. The printed wiring board connection structure according to claim 24 , wherein the printed wiring board connection structure is in close contact with a protective film formed on a conductor pattern of the first printed wiring board.

Said first printed circuit board protective film formed on the conductive pattern of the connection structure of a printed wiring board according to any one of claims 2 3 to 27, characterized in that it is formed from a thermoplastic resin material .

Conductor patterns of the first and second printed circuit board, each of the plurality of wires and the printed circuit according to any one of claims 2 3 to 28, wherein Rukoto that have a connected land that wire Board connection structure.

The conductor pattern land formed on the connection surface of the first printed wiring board using thermoplastic resin as the insulating substrate material is electrically connected to the land of the conductor pattern formed on the connection surface of the second printed wiring board. Printed wiring board connection structure,
In the first printed wiring board, a protective film for covering the conductor pattern is provided except for the land of the conductor pattern, and ends of the protective film cover the first printed circuit on both sides while covering the conductor pattern. It is formed in a convex shape so as to expose the surface of the wiring board,
The conductor pattern of the second printed wiring board is formed so that the end thereof is terminated at a position away from the connection surface tip by a predetermined distance,
The portion of the thermoplastic resin exposed from the protective film of the first printed wiring board is brought into close contact with the front end portion of the connection surface of the second printed wiring board, and the first printed wiring board and the second printed circuit board. The conductor pattern at the connection point with the printed wiring board is sealed with a thermoplastic resin constituting the first printed wiring board,
In the connection surface of the first printed wiring board, the conductor pattern is formed so as to terminate at a position away from the connection surface tip portion by a predetermined distance, and the thermoplastic resin at the connection surface tip portion is the second surface. Is closely attached to the connection surface of the printed wiring board
The thermoplastic resin, the connection structure of the print wiring board, wherein Rukoto a single layer of polyether ether ketone resin containing 65 to 35 wt% and a polyetherimide resin 35-65 wt%.

31. The printed wiring board connection structure according to claim 30 , wherein a protective film is formed on the conductor pattern of the second printed wiring board except for the land .

The conductor patterns of the first and second printed wiring board, the connection structure of a printed wiring board according to claim 3 0 or 3 1 each comprising a plurality of wirings and lands that are connected to the wiring .