JP3600295B2

JP3600295B2 - Manufacturing method of printed wiring board

Info

Publication number: JP3600295B2
Application number: JP2739895A
Authority: JP
Inventors: 弘福川; 裕助和田
Original assignee: Toshiba Corp; Kyocera Chemical Corp
Current assignee: Toshiba Corp; Kyocera Chemical Corp
Priority date: 1995-01-23
Filing date: 1995-01-23
Publication date: 2004-12-15
Anticipated expiration: 2019-12-15
Also published as: JPH08204332A

Description

【０００１】
【産業上の利用分野】
本発明は、配線層間を貫通型の導体配線部で接続する、高密度な配線および実装を可能とする信頼性の高い印刷配線板の製造方法に関する。
【０００２】
【従来の技術】
従来、両面印刷配線板もしくは多層印刷配線板において、導電パターン等の配線層の間の電気的接続は、次のようにして行っていた。例えば、両面印刷配線板の場合は、両面銅張基板の所定位置に穴明け加工を施し、穴の内壁面を含めて全面に化学メッキ処理を施してから電気メッキ処理で穴の内壁面の金属層を厚くして信頼性を高め、配線層間の電気的な接続を行っている。また、多層印刷配線板の場合は、内層銅張基板両面に貼られた銅箔をそれぞれパターニングした後、そのパターニング面上に絶縁シート（例えばプリプレグ）を介して銅箔を積層・配置し、加熱加圧により一体化した後、両面印刷配線板のときと同様に、穴明け加工およびメッキ処理による配線層間の電気的接続を行った後、表面銅箔をパターニングすることにより４層の多層印刷配線板を得ている。なお、４層より配線層の多い多層印刷配線板の場合は、中間に介挿させる内層銅張基板の枚数を増やす方式で製造できる。
【０００３】
前記印刷配線板の製造方法において、配線層間の電気的な接続をメッキ処理によらず行う方法として、両面銅張基板の所定位置に穴明けし、この穴内に導電性ペーストを印刷法などにより流し込み、穴内に流し込んだ導電性ペーストの樹脂分を硬化させて、配線層間を電気的に接続する方法も行われている。
【０００４】
【発明が解決しようとする課題】
上述したように、配線層間の電気的接続にメッキ法を利用する印刷配線板の製造方法においては、配線層間の電気的な接続用の基板穴明け（穿穴）加工、穿設した穴内壁面を含めたメッキ処理工程などを要し、製造工程が冗長であるとともに工程管理も繁雑であるという欠点がある。
【０００５】
一方、配線層間の電気的接続用の穴に、導電性ペーストを印刷などにより埋め込む方法の場合も、前記メッキ法の場合と同様に基板穴明け工程を必要とする。しかも、穿設した穴内に、導電性ペーストを均一に流し込むことが難しく、電気的接続の信頼性に問題があった。いずれにしても、前記穴明け工程などを要することは、印刷配線板のコストや歩留りなどに反映し、低コスト化などの要望に対応し得ないという欠点がある。
【０００６】
また、前記メッキ処理あるいは導電性ペースト流込みによる電気的接続ではいずれの場合にも、印刷配線板の表裏面に、配線層間接続用の導電体穴が設置されているため、その導電体穴の領域には配線を形成・配置し得ないし、さらに電子部品を搭載することもできないので、配線密度の向上が制約されるとともに、電子部品実装密度の向上も阻害されるという問題がある。つまり従来の製造方法によって得られる印刷配線板は、高密度配線や高密度実装による回路装置のコンパクト化、ひいては電子機器類の小型化などの要望に、十分応え得るものとはいえず、前記コスト面を含め、実用的により有効な印刷配線板の製造方法が望まれていた。
【０００７】
それに応えるため、発明者は合成樹脂系シートの厚さ方向に、バンプ群をそれぞれ貫挿させて貫通型の導体配線部を形成し、合成樹脂系シートの上面に配置した金属箔を接続する方法を提案したが、合成樹脂系シートが厚いと導体バンプの径を大きくしなければ合成樹脂系シートを貫挿させることができず、回路密度や絶縁層厚さの制限があった。
【０００８】
本発明は、上記の欠点や問題点を解消するためになされたもので、導体バンプの貫挿性を向上させ、かつ貫通型の導体配線部と積層体の導電性金属箔との接続信頼性を向上させ、歩留り良好でコスト低減に寄与する印刷配線板の製造方法を提供しようとするものである。
【０００９】
【課題を解決するための手段】
本発明は、上記の目的を達成しようと鋭意研究を重ねた結果、導体バンプ群を形成貫挿させる工程を複数回行うことによって、上記の目的を達成できることを見いだし、本発明を完成したものである。
【００１０】
即ち、本発明は、支持基体の主面における所定位置に導体バンプ群を形設する第一工程と、前記支持基体の主面に合成樹脂系シートの主面を対接させて積層配置して加圧し、前記合成樹脂系シートの厚さ方向に前記導体バンプ群をそれぞれ貫挿させて貫通型の導体配線部を形成する第二工程と、前記貫通型の導体配線部の貫挿した合成樹脂系シートから露出する前記導体バンプ群の先端部に重ねて新たな導体バンプ群を形設する第三工程と、その積層物の導体バンプ形設面に合成樹脂系シートの主面を対接させて積層配置して加圧し、前記合成樹脂系シートの厚さ方向に前記導体バンプ群をそれぞれ貫挿させて貫通型の導体配線部を形成する第四工程と、前記貫通型の導体配線部を貫挿させた合成樹脂系シートの上面に導電性金属箔を配置し一体成形する第五工程とを具備し、前記第三及び第四工程を少なくとも1 回以上複数回行うことを特徴とする印刷配線板の製造方法である。
【００１１】
以下、本発明を詳細に説明する。
【００１２】
本発明の第一及び第三工程において形設する導体バンプ群は、バインダーとなる合成樹脂に導電性粉末を配合した導電性組成物を用いて形成される。バインダーとなる合成樹脂としては、熱硬化性樹脂、熱可塑性樹脂あるいはこれらの混合樹脂が使用できる。例えば、ユリア樹脂、メラミン樹脂、フェノール樹脂、レゾルシノール樹脂、エポキシ樹脂、ポリウレタン樹脂、酢酸ビニル樹脂、ポリビニルアルコール樹脂、アクリル樹脂、ビニルウレタン樹脂、シリコーン樹脂、α−オレフィン無水マレイン酸樹脂、ポリアミド樹脂、ポリイミド樹脂等が挙げられ、これらは単独または２種以上混合して使用することができる。また、ここで用いる導電性粉末としては、金粉末、銀粉末、銅粉末、ニッケル粉末、カーボン粉末、表面に導電物層を有する粉末等が挙げられ、これらは単独または２種以上混合して使用することができる。導電性組成物は、合成樹脂と導電性粉末を主成分として配合したものであるが、本発明の目的に反しない程度において、また必要に応じて、粘度調整用の溶剤、カップリング剤、その外の添加物を配合することができる。ここで用いる溶剤としては、ジオキサン、ベンゼン、ヘキサン、トルエン、ソルベントナフサ、工業用ガソリン、酢酸セロソルブ、エチルセロソルブ、ブチルセロソルブアセテート、ブチルカルビトールアセテート、ジメチルホルムアミド、ジメチルアセトアミド、Ｎ−メチルピロリドン等が挙げられ、これらは単独または２種以上混合して使用することができる。こうして得られる導電性組成物を用いてバンプ群を形成する。
【００１３】
導体バンプ群の形成手段としては、比較的厚いメタルマスクを用いた印刷法等が挙げられるが、特に制限されるものではない。１種類の導電性組成物を数回繰り返し印刷して導体バンプ群を形成するが、異なる２種以上の導電性組成物を１種類につき各１回以上繰り返し印刷することによって、異なる２種以上の導電性組成物の２層以上の導体バンプを形成することができる。そのバンプ群の高さは一般的に１００〜４００ μｍ程度が望ましく、さらに導体バンプ群の高さは１層の合成樹脂系シートを貫通し得る高さ及び複数層の合成樹脂系シートを貫通し得る高さとが適宜混在していてもよい。
【００１４】
本発明の第一工程に用いる支持基体、つまりバンプ群が形設される支持基体としては、例えば剥離性良好な合成樹脂系シート類、もしくは導電性シート（箔）などが挙げられ、この支持基体は１枚のシートであってもよいし、パターン化されたものでもよく、その形状は特に限定されない。さらに導体バンプ群は、支持基体の一方の主面だけでなく、両主面にそれぞれ形設したものを用いてもよい。
【００１５】
本発明の第二及び第四工程において用いる合成樹脂系シートとしては、前記導体バンプ群が貫挿され、貫通型の導体配線部を形成するもので、その厚さは５０〜８００ μｍ程度が好ましい。具体的な合成樹脂系シートとして、まず熱可塑性樹脂フィルム、例えば、ポリカーボネート樹脂、ポリスルホン樹脂、熱可塑性ポリイミド樹脂、４フッ化ポリエチレン樹脂、６フッ化ポリプロピレン樹脂、ポリエーテルエーテルケトン樹脂等のシート類が挙げられる。次に、硬化前状態に保持される熱硬化性樹脂シート、例えば、エポキシ樹脂、ビスマレイミドトリアジン樹脂、ポリイミド樹脂、フェノール樹脂、ポリエステル樹脂、メラミン樹脂等のプリプレグ類が挙げられ、或いは生ゴムシート類、例えば、ブタジエンゴム、ブチルゴム、天然ゴム、ネオプレンゴム、シリコーンゴムなどのシートが挙げられる。これらの合成樹脂系シートは、合成樹脂単独でもよいが無機物や有機物系の絶縁性充填物を含有してもよく、さらにガラスクロスやマット、有機合成繊維布やマット、或いは紙等の補強材と組み合わせてなるシートであってもよい。
【００１６】
上述の導電性組成物を用いて導体バンプ群を形設することを第一工程とした支持基体の主面に、合成樹脂系シート（プリプレグ）主面を対接させて積層配置し、その積層体をそのままもしくは加熱加圧して合成樹脂系シートに導体バンプ群を貫挿することを第二工程とするのであるが、そのとき、合成樹脂系シートを載置する基台（当て板）としては、寸法や変形の少ない金属板もしくは耐熱性樹脂板、例えばステンレス板、真鍮板、ポリイミド樹脂板（シート）、ポリテトラフロロエチレン樹脂板（シート）等が使用される。この積層体の加圧に際し、加熱して合成樹脂系シートの樹脂分が柔らかくなった状態で加圧すれば、良好なバンプ群の貫挿をさせることができる。
【００１７】
本発明で最も重要なことは、第二工程を経て導体配線部を形成した積層物に、第一工程と同様に導体バンプ群を形設する第三工程と、導体バンプ群を形設した積層物に第二工程と同様に合成樹脂系シートを重ねて貫通型の導体配線部を形成する第四工程を繰り返すことにある。そのように合成樹脂系シートの厚さ方向に前記導体バンプ群をそれぞれ貫挿させて貫通型の導体配線部を形成する工程を複数回行うことによって、貫挿性を向上させることである。こうして印刷配線板が製造できる。
【００１８】
【作用】
本発明の印刷配線板の製造方法によれば、合成樹脂系シートの厚さ方向に導体バンプ群を貫挿させて貫通型の導体配線部を形成する工程を複数回行うことによって、前記導体バンプ径を大きくすることなく、合成樹脂系シートを容易に貫挿させ、かつ貫通型の導体配線部と積層体の導電性金属箔との接続信頼性を向上させるものである。
【００１９】
【実施例】
本発明の実施例を図面を用いて具体的に説明するが、本発明はこれらの実施例によって限定されるものではない。
【００２０】
実施例
図１（ａ）に示したように、厚さ３５μｍの電解銅箔を支持基体１として、熱可塑性アクリル樹脂系銀ペーストＡをメタルマスク（ステンレス製、板厚０．２ｍｍ、穴径０．４ｍｍ、図示せず）を用いて印刷、乾燥後、同一マスクを用い、同一位置に印刷することを４回繰り返し、高さ約２００μｍの導体バンプ２を形成した。次に合成樹脂系シートとして、ガラスクロスにエポキシ樹脂を含浸してなる厚さ１００ μｍのプリプレグ３を用い、積層配置して加圧し、前記プリプレグ３の厚さ方向に、前記バンプ群２をそれぞれ貫挿させて図１（ｂ）に示したように貫通型の導体配線部４を形成した。次いで、導体バンプ群をそれぞれ貫挿させて貫通型の導体配線部４を形成した前記プリプレグに、上記熱可塑性アクリル樹脂系銀ペーストＡをメタルマスクを用いて印刷、乾燥硬化後、同一マスクを用い、同一位置に印刷することを４回繰り返し、高さ約２００μｍの導体バンプ２′を形成した。図１（ｃ）に示したように導体バンプ群２′に上記と同様にしてガラスクロスにエポキシ樹脂を含浸してなる厚さ１００ μｍのプリプレグ３′を積層配置して加圧し、プリプレグ３′の厚さ方向に、前記導体バンプ群２′をそれぞれ貫挿させて図１（ｄ）に示したように貫通型の導体配線部４′を形成した。次いで図１（ｅ）に示したように、裏面シート（当て板兼用）として用いる厚さ３５μｍの電解銅箔５を積層配置して加圧し、１７０ ℃，５０ｋｇ／ｃｍ^２で９０分間、加熱加圧一体に成形して両面印刷配線板を製造した。
【００２１】
比較例
図２（ａ）に示したように、支持基体として厚さ３５μｍの電解銅箔１１に、熱可塑性アクリル樹脂系銀ペーストＡをメタルマスク（前出）を用いて印刷、乾燥後、同一マスクを用い、同一位置に印刷することを４回繰り返し、高さ約２００μｍの導体バンプ１２を形成した。次いで導体バンプ群１２を形成した支持基体１１と、裏面シート（当て板兼用）として用いる厚さ３５μｍの電解銅箔１５の上に合成樹脂系シートとして、ガラスクロスにエポキシ樹脂を含浸してなる厚さ２００ μｍのプリプレグ１３を用い、積層配置して加圧し、図２（ｂ）のように、プリプレグ１３の厚さ方向に前記バンプ群をそれぞれ貫挿させて貫通型の導体配線部１４を形成した。次いで、図２（ｃ）のように、１７０ ℃，５０ｋｇ／ｃｍ^２で９０分間、加熱加圧一体に成形して両面印刷配線板を製造した。
【００２２】
実施例及び比較例で製造した印刷配線板について、バンプ貫通率、スルーホール信頼性を試験したのでその結果を表１に示した。本発明は優れた特性を示し、本発明の効果を確認することができた。
【００２３】
【表１】

【００２４】
【発明の効果】
以上の説明および表１から明らかなように、本発明の印刷配線板の製造方法によればバンプの貫挿性を向上させ、かつ貫通型の導体配線部と積層体の導電性金属箔との信頼性を向上させ、歩留り良好でコスト低減に寄与する印刷配線板を製造することができる。
【図面の簡単な説明】
【図１】図１（ａ）〜（ｅ）は、本発明の印刷配線板の製造工程を説明する模式図である。
【図２】図２（ａ）〜（ｃ）は、従来方法による貫通型導体配線部の形成工程を説明する模式図である。
【符号の説明】
１，１１電解銅箔（支持基体）
２，２′，１２導体バンプ
３，３′，１３合成樹脂系シート
４，１４導体配線部
５，１５電解銅箔[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a highly reliable printed wiring board that enables high-density wiring and mounting, in which wiring layers are connected by through-type conductive wiring portions.
[0002]
[Prior art]
Conventionally, in a double-sided printed wiring board or a multilayer printed wiring board, electrical connection between wiring layers such as conductive patterns has been performed as follows. For example, in the case of a double-sided printed wiring board, a hole is formed at a predetermined position on a double-sided copper-clad board, a chemical plating process is performed on the entire surface including an inner wall surface of the hole, and then a metal plating on the inner wall surface of the hole is performed by electroplating. The thickness is increased to improve reliability, and electrical connection between wiring layers is performed. In the case of a multilayer printed wiring board, after patterning the copper foil adhered on both sides of the inner layer copper-clad board, the copper foil is laminated and arranged on the patterned surface via an insulating sheet (for example, prepreg), and heated. After being integrated by pressurization, as in the case of a double-sided printed wiring board, electrical connection between wiring layers is made by drilling and plating, and then the surface copper foil is patterned to form a multilayer printed wiring of four layers. I'm getting a board. In the case of a multilayer printed wiring board having more wiring layers than four layers, it can be manufactured by a method of increasing the number of inner-layer copper-clad substrates to be inserted in the middle.
[0003]
In the method of manufacturing a printed wiring board, as a method of performing electrical connection between wiring layers without using a plating process, a hole is formed in a predetermined position of a double-sided copper-clad board, and a conductive paste is poured into the hole by a printing method or the like. There is also a method in which a resin component of a conductive paste poured into a hole is cured to electrically connect wiring layers.
[0004]
[Problems to be solved by the invention]
As described above, in a method of manufacturing a printed wiring board using a plating method for electrical connection between wiring layers, a substrate hole for electrical connection between wiring layers (perforation) is formed, and a hole inner wall surface is formed. It requires a plating process step and the like, and has the disadvantage that the manufacturing process is redundant and the process management is complicated.
[0005]
On the other hand, a method of embedding a conductive paste in a hole for electrical connection between wiring layers by printing or the like also requires a substrate drilling step as in the case of the plating method. Moreover, it is difficult to uniformly pour the conductive paste into the drilled holes, and there is a problem in the reliability of the electrical connection. In any case, the necessity of the drilling step and the like is reflected in the cost and yield of the printed wiring board, and has a drawback in that it cannot meet demands for cost reduction and the like.
[0006]
In any case of the electrical connection by the plating process or the inflow of the conductive paste, the conductor holes for connecting the wiring layers are provided on the front and back surfaces of the printed wiring board. Since wiring cannot be formed and arranged in the region and electronic components cannot be mounted on the region, there is a problem that the improvement in wiring density is restricted and the improvement in electronic component mounting density is hindered. In other words, the printed wiring board obtained by the conventional manufacturing method cannot sufficiently meet the demands for downsizing of circuit devices by high-density wiring and high-density mounting, and furthermore, downsizing of electronic devices and the like, and cannot be said to be cost-effective. There has been a demand for a practically more effective method of manufacturing a printed wiring board, including the surface.
[0007]
In order to respond to this, the inventor formed a through-type conductor wiring portion by inserting a bump group in the thickness direction of the synthetic resin-based sheet, and connected a metal foil disposed on the upper surface of the synthetic resin-based sheet. However, if the synthetic resin sheet is thick, the synthetic resin sheet cannot be penetrated unless the diameter of the conductor bumps is increased, and the circuit density and the thickness of the insulating layer are limited.
[0008]
The present invention has been made in order to solve the above-mentioned drawbacks and problems, and has improved the penetrability of a conductor bump, and the connection reliability between a through-type conductor wiring portion and a conductive metal foil of a laminate. It is an object of the present invention to provide a method of manufacturing a printed wiring board which improves the yield, improves the yield, and contributes to cost reduction.
[0009]
[Means for Solving the Problems]
The present invention, as a result of intensive studies to achieve the above object, found that the above object can be achieved by performing the step of forming and inserting the conductor bump group a plurality of times, and completed the present invention. is there.
[0010]
That is, the present invention provides a first step of forming a conductor bump group at a predetermined position on a main surface of a support base, and laminating the main surface of the support base with a main surface of a synthetic resin sheet facing the main surface. A second step of applying pressure and penetrating the conductor bumps in the thickness direction of the synthetic resin-based sheet to form a penetrating conductive wiring portion ; and a synthetic resin penetrating the penetrating conductive wiring portion. A third step of forming a new conductor bump group by superimposing the tip of the conductor bump group exposed from the system sheet, and contacting the main surface of the synthetic resin sheet with the conductor bump formation surface of the laminate. A fourth step of forming a through-type conductive wiring portion by inserting the conductive bump groups in the thickness direction of the synthetic resin-based sheet to form a through-type conductive wiring portion; and Conductive metal foil is placed on the top of the synthetic resin sheet ; And a fifth step of the body molding is a manufacturing method of the printed wiring board and the third and the fourth step characterized by performing at least once more times.
[0011]
Hereinafter, the present invention will be described in detail.
[0012]
The group of conductive bumps formed in the first and third steps of the present invention is formed using a conductive composition obtained by mixing a conductive powder with a synthetic resin serving as a binder. As the synthetic resin serving as the binder, a thermosetting resin, a thermoplastic resin, or a mixed resin thereof can be used. For example, urea resin, melamine resin, phenol resin, resorcinol resin, epoxy resin, polyurethane resin, vinyl acetate resin, polyvinyl alcohol resin, acrylic resin, vinyl urethane resin, silicone resin, α-olefin maleic anhydride resin, polyamide resin, polyimide And the like. These can be used alone or in combination of two or more. Examples of the conductive powder used herein include gold powder, silver powder, copper powder, nickel powder, carbon powder, and powder having a conductive layer on the surface. These may be used alone or as a mixture of two or more. can do. The conductive composition is a composition containing a synthetic resin and a conductive powder as main components, but to the extent that the purpose of the present invention is not violated, and if necessary, a solvent for adjusting viscosity, a coupling agent, and the like. Outside additives can be compounded. Examples of the solvent used here include dioxane, benzene, hexane, toluene, solvent naphtha, industrial gasoline, cellosolve acetate, ethyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like. These can be used alone or in combination of two or more. A bump group is formed using the conductive composition thus obtained.
[0013]
Examples of the means for forming the conductor bump group include a printing method using a relatively thick metal mask, but are not particularly limited. One kind of conductive composition is repeatedly printed several times to form a conductive bump group. By printing two or more different conductive compositions one or more times for each kind repeatedly, two or more different conductive compositions are printed. Two or more conductive bumps of the conductive composition can be formed. In general, the height of the bump group is desirably about 100 to 400 μm, and the height of the conductive bump group is a height that can penetrate a single-layer synthetic resin sheet and a height that can penetrate a plurality of synthetic resin sheets. The height to be obtained may be appropriately mixed.
[0014]
The support substrate used in the first step of the present invention, that is, the support substrate on which the bump group is formed, includes, for example, synthetic resin-based sheets having good releasability, or a conductive sheet (foil). May be a single sheet or a patterned sheet, and its shape is not particularly limited. Further, the conductor bump group may be formed not only on one main surface of the support base but also on both main surfaces.
[0015]
As the synthetic resin sheet used in the second and fourth steps of the present invention, the conductor bump group is inserted to form a through-type conductor wiring portion, and the thickness thereof is preferably about 50 to 800 μm. . Specific examples of the synthetic resin-based sheet include thermoplastic resin films, for example, sheets of polycarbonate resin, polysulfone resin, thermoplastic polyimide resin, tetrafluoroethylene resin, hexafluoropropylene resin, polyetheretherketone resin, and the like. No. Next, thermosetting resin sheets held in a pre-cured state, for example, prepregs such as epoxy resin, bismaleimide triazine resin, polyimide resin, phenol resin, polyester resin, melamine resin, or raw rubber sheets, For example, sheets of butadiene rubber, butyl rubber, natural rubber, neoprene rubber, silicone rubber and the like can be mentioned. These synthetic resin-based sheets may be made of a synthetic resin alone or may contain an inorganic or organic insulating filler, and may further include a glass cloth or mat, an organic synthetic fiber cloth or mat, or a reinforcing material such as paper. The sheets may be combined.
[0016]
The first step is to form a group of conductive bumps using the conductive composition described above, and the main surface of the support base is laminated and arranged with the main surface of the synthetic resin sheet (prepreg) facing the main surface. The second step is to insert the conductor bumps into the synthetic resin sheet as it is or by heating and pressing the body as it is. At this time, the base (plate) on which the synthetic resin sheet is placed For example, a metal plate or a heat-resistant resin plate having small dimensions and deformation, such as a stainless steel plate, a brass plate, a polyimide resin plate (sheet), and a polytetrafluoroethylene resin plate (sheet) are used. When the laminate is pressed, the bumps can be satisfactorily penetrated by heating and pressurizing the synthetic resin sheet in a state where the resin component is softened.
[0017]
Most importantly in the present invention, the third step of forming the conductor bump group as in the first step, and the lamination of forming the conductor bump group on the laminate in which the conductor wiring portion has been formed through the second step The fourth step is to repeat the fourth step of forming a through-type conductor wiring portion by stacking a synthetic resin-based sheet on the object in the same manner as the second step. It is an object of the present invention to improve the penetrability by performing a plurality of steps of forming the penetrating-type conductor wiring portion by penetrating the conductor bump groups in the thickness direction of the synthetic resin-based sheet. Thus, a printed wiring board can be manufactured.
[0018]
[Action]
According to the method of manufacturing a printed wiring board of the present invention, the step of forming a through-type conductor wiring portion by inserting a group of conductor bumps in the thickness direction of the synthetic resin-based sheet is performed a plurality of times. An object of the present invention is to easily insert a synthetic resin sheet without increasing the diameter and to improve the connection reliability between the penetrating conductive wiring portion and the conductive metal foil of the laminate.
[0019]
【Example】
Examples of the present invention will be specifically described with reference to the drawings, but the present invention is not limited to these examples.
[0020]
EXAMPLE As shown in FIG. 1 (a), a 35 .mu.m-thick electrolytic copper foil was used as a supporting substrate 1 and a thermoplastic acrylic resin-based silver paste A was used as a metal mask (made of stainless steel, plate thickness 0.2 mm, hole diameter 0). After printing and drying using the same mask and printing at the same position four times, the conductive bumps 2 having a height of about 200 μm were formed. Next, as a synthetic resin sheet, a prepreg 3 having a thickness of 100 μm formed by impregnating a glass cloth with an epoxy resin is used, laminated and pressed, and the bump groups 2 are respectively arranged in the thickness direction of the prepreg 3. The through-type conductor wiring portion 4 was formed as shown in FIG. Next, the above-mentioned thermoplastic acrylic resin-based silver paste A is printed using a metal mask on the prepreg in which the conductive bump groups are inserted and the through-type conductive wiring portions 4 are formed, and after drying and curing, the same mask is used. Printing at the same position was repeated four times to form a conductor bump 2 'having a height of about 200 μm. As shown in FIG. 1 (c), a prepreg 3 'having a thickness of 100 [mu] m made of glass cloth impregnated with an epoxy resin is laminated on the conductor bump group 2' in the same manner as described above, and pressurized. The conductor bumps 2 'were respectively inserted in the thickness direction to form a through-type conductor wiring portion 4' as shown in FIG. 1 (d). Next, as shown in FIG. 1 (e), a 35 μm-thick electrolytic copper foil 5 used as a back sheet (also used as a backing plate) is laminated and pressed, and heated at 170 ° C. and 50 kg / cm ² for 90 minutes. A double-sided printed wiring board was manufactured by pressing and molding.
[0021]
Comparative Example As shown in FIG. 2A, a thermoplastic acrylic resin-based silver paste A was printed on a 35 μm-thick electrolytic copper foil 11 as a support base using a metal mask (described above), dried, and then dried. Using a mask, printing at the same position was repeated four times to form conductive bumps 12 having a height of about 200 μm. Next, a glass cloth is impregnated with epoxy resin as a synthetic resin-based sheet on a support base 11 on which the conductor bump group 12 is formed and an electrolytic copper foil 15 having a thickness of 35 μm used as a back sheet (also used as a backing plate). Using a prepreg 13 having a thickness of 200 μm, the prepreg 13 is stacked and pressed, and as shown in FIG. 2B, the bump groups are respectively inserted in the thickness direction of the prepreg 13 to form a through-type conductor wiring portion 14. did. Next, as shown in FIG. 2C, the double-sided printed wiring board was manufactured by integrally heating and pressing at 170 ° C. and 50 kg / cm ² for 90 minutes.
[0022]
The printed wiring boards manufactured in Examples and Comparative Examples were tested for bump penetration ratio and through hole reliability, and the results are shown in Table 1. The present invention exhibited excellent characteristics, and the effects of the present invention could be confirmed.
[0023]
[Table 1]

[0024]
【The invention's effect】
As apparent from the above description and Table 1, according to the method for manufacturing a printed wiring board of the present invention, the penetrability of the bump is improved, and the conductive metal foil of the laminated body and the conductive metal foil of the laminate are formed. It is possible to manufacture a printed wiring board that improves reliability, improves yield, and contributes to cost reduction.
[Brief description of the drawings]
FIGS. 1A to 1E are schematic views illustrating a process for manufacturing a printed wiring board according to the present invention.
FIGS. 2A to 2C are schematic views illustrating a process of forming a through conductor wiring portion according to a conventional method.
[Explanation of symbols]
1,11 Electrolytic copper foil (support base)
2, 2 ', 12 conductor bumps 3, 3', 13

synthetic resin sheet

4, 14

conductor wiring portion

5, 15 electrolytic copper foil

Claims

A first step of forming a group of conductive bumps at predetermined positions on the main surface of the support base; A second step of penetrating the conductor bumps in the thickness direction of the system sheet to form a through-type conductor wiring portion, and exposing the through-type conductor wiring portion from the penetrated synthetic resin-based sheet. A third step of forming a new conductive bump group by superimposing on the tip of the conductive bump group, and adding and stacking the synthetic resin sheet with the main surface of the synthetic resin sheet facing the conductive bump forming surface of the laminate. Pressing, forming a through-type conductive wiring portion by penetrating the conductive bump groups in the thickness direction of the synthetic resin-based sheet, and a synthetic resin having the through-type conductive wiring portion inserted therethrough. Fifth, in which conductive metal foil is placed on the upper surface of the base sheet and integrally molded ; And a degree, a method of manufacturing a printed wiring board, which comprises carrying out at least one time a plurality of times the third and fourth step.