JP4200273B2 - Mounting board manufacturing method - Google Patents

Mounting board manufacturing method Download PDF

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Publication number
JP4200273B2
JP4200273B2 JP2002203809A JP2002203809A JP4200273B2 JP 4200273 B2 JP4200273 B2 JP 4200273B2 JP 2002203809 A JP2002203809 A JP 2002203809A JP 2002203809 A JP2002203809 A JP 2002203809A JP 4200273 B2 JP4200273 B2 JP 4200273B2
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Japan
Prior art keywords
solder
mounting
electrode
thermosetting
substrate
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Expired - Fee Related
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JP2002203809A
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JP2004047773A (en
Inventor
俊和 松尾
忠彦 境
憲 前田
誠一 吉永
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Panasonic Corp
Panasonic Holdings Corp
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Panasonic Corp
Matsushita Electric Industrial Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
    • H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
    • H01L2224/161—Disposition
    • H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32225—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73201—Location after the connecting process on the same surface
    • H01L2224/73203—Bump and layer connectors
    • H01L2224/73204—Bump and layer connectors the bump connector being embedded into the layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H01L2224/8319—Arrangement of the layer connectors prior to mounting
    • H01L2224/83192—Arrangement of the layer connectors prior to mounting wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/19—Details of hybrid assemblies other than the semiconductor or other solid state devices to be connected
    • H01L2924/191—Disposition
    • H01L2924/19101—Disposition of discrete passive components
    • H01L2924/19106—Disposition of discrete passive components in a mirrored arrangement on two different side of a common die mounting substrate

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  • Electric Connection Of Electric Components To Printed Circuits (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、電子部品を基板に実装して実装基板を製造する実装基板の製造方法に関するものである。
【０００２】
【従来の技術】
半導体チップなどの電子部品の実装方法として、半田接合による方法が広く用いられている。この半田接合の方式として、熱硬化性の樹脂接着材を部品搭載前に予め基板の電極上に塗布する方法が採用されるようになっている。この方法では、電子部品の半田バンプを電極上に着地させた後に基板を加熱することにより、半田バンプと電極との半田接合と樹脂接着材の熱硬化とを同一加熱工程にて行う。この方法によれば、補強用のアンダーフィル樹脂形成工程を独立した工程として設ける必要がないという利点を有している。
【０００３】
【発明が解決しようとする課題】
しかしながら、上記樹脂接着材を用いた電子部品の実装過程においては、次のような不都合が生じる場合があった。前述のように塗布された樹脂接着材は、半田接合のためのリフロー時の加熱によって熱硬化させるようになっているが、一般に半田接合のための加熱プロファイルにおいて樹脂が熱硬化温度以上に保持される時間と、樹脂を完全に熱硬化させるために必要な熱硬化時間とは符合せず、リフロー時の加熱時間は樹脂の完全硬化には時間的に不十分な場合が多い。このため、従来は樹脂硬化を完了させることを目的としたキュア工程をリフロー後に別途設けることが多かった。そしてこのキュア工程においては、長時間の加熱を必要としていた。
【０００４】
そこで本発明は、樹脂接着材を用いて行われる実装基板の製造において、樹脂完全硬化のための後キュア工程を省略またはキュア時間を短縮して、生産性を向上させることができる実装基板の製造方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
請求項１記載の実装基板の製造方法は、基板の第１面と第１面の裏側の第２面にそれぞれ電子部品が実装された実装基板を製造する実装基板の製造方法であって、部品実装工程において先に実装対象となる第１面に、活性作用を有し実装に使用される半田の融点温度よりも高い熱硬化温度を有する熱硬化性樹脂を含む半田接合用ペーストを前記第１面に設けられた第１電極を覆って供給する第１ペースト供給工程と、ペースト供給後の第１面に半田バンプが設けられた電子部品を搭載して電子部品の半田バンプを第１面に設けられた第１電極に着地させる第１搭載工程と、第１搭載工程後の前記基板を加熱して前記半田バンプを溶融させて半田バンプを第１電極に半田接合するとともに前記熱硬化性樹脂の熱硬化を開始させる第１加熱工程と、第１面の実装が完了した基板の第２面に前記熱硬化性樹脂を含まない半田接合用ペーストであるクリーム半田を供給する第２ペースト供給工程と、ペースト供給後の第２面に電子部品を搭載して電子部品の接続用電極を前記第２面に設けられた第２電極に着地させる第２搭載工程と、第２搭載工程後の前記基板を加熱して前記接続用電極を第２電極に半田接合するとともに前記第１面の熱硬化性樹脂の熱硬化を再開させる第２加熱工程とを含み、前記第１加熱工程において前記熱硬化性樹脂中における溶融半田の流動性が確保され、前記半田バンプと第１電極とのセルフアライメントが阻害されない。
【０００８】
本発明によれば、先に実装対象となる第１面のみに熱硬化性樹脂を含む半田接合用ペーストを供給し、この半田接合用ペーストの熱硬化を、第１面を対象とする第１加熱工程と第２面を対象とする第２加熱工程の２回にわたって行うことにより、熱硬化を極力促進して後キュア工程を省略またはキュア時間を短縮することができる。
【０００９】
【発明の実施の形態】
次に本発明の実施の形態を図面を参照して説明する。図１、図２は本発明の一実施の形態の実装基板の製造方法の工程説明図、図３は本発明の一実施の形態の実装基板の製造方法におけるリフロー工程の温度プロファイルを示すグラフである。本実施の形態では、両面に電極が形成された基板に電子部品を半田接合により実装して実装基板を製造する工程を示している。
【００１０】
図１（ａ）において、１は両面実装用の基板であり、基板１の第１面１ａ（図１において上面）および第１面の裏側の第２面１ｂ（図１において下面）には、それぞれ第１電極としての電極２，第２電極としての電極３が形成されている。第１面１ａは、基板１の表裏両面に電子部品を実装して実装基板を製造する過程において、先に実装対象となる面である。
【００１１】
図１（ｂ）に示すように、第１面１ａの電極２の周囲には、半田接合用ペーストである樹脂接着材４がディスペンサ５によって電極２を覆って供給される（第１ペースト供給工程）。樹脂接着材４は、エポキシ樹脂などの熱硬化性樹脂を主成分とする基剤に、酸化膜除去能力を有する活性成分を含有させることにより、電子部品の下面を封止して補強する接着機能に加えて、半田接合時に半田表面の酸化膜を除去して半田接合性を向上させるフラックスとしての機能を兼ねさせたものである。この樹脂接着材４は、含有する活性成分によって半田バンプ表面の酸化膜を除去することから別途フラックスを塗布する必要がなく、フラックスを用いた従来方法において必要とされたリフロー後の洗浄工程を省略できるという利点を有している。
【００１２】
ここでは、基剤の熱硬化温度として、実装に使用される半田の融点温度よりも高い熱硬化温度を有するものを用いている。半田融点温度は、Ｓｎ／Ｐｂ系の半田では１８３℃，Ｓｎ／Ａｇ系では２２０℃である。なお、本実施の形態でいう熱硬化温度とは、樹脂材料の硬化反応の測定に使用される示差走査熱量測定（ＤＳＣ）により求められた温度である。すなわち、１０ｍｇの試料を昇温レートが１０℃／分の条件で加熱する過程において得られる熱量と温度との関係を、縦軸に熱量、横軸に温度をとってプロットしてグラフ化すると山形の曲線が形成される。そしてこの山形の曲線の高温側の斜面における変曲点から接線を引き、この接線が横軸が交わる温度を求めて熱硬化温度とする。
【００１３】
次いで図１（ｃ）に示すように、ペースト供給後の第１面１ａには、下面に接続用電極としての半田バンプ７が設けられた電子部品６が搭載され（第１搭載工程）、これにより半田バンプ７は樹脂接着材４を介して電極２上に着地する。そしてこの後、基板１は第１面１ａを対象とした第１面リフローのためにリフロー工程に送られ。ここで所定の加熱プロファイルにしたがって加熱される（第１加熱工程）。
【００１４】
この第１面リフローにおける加熱プロファイルについて、図３を参照して説明する。加熱が開始されると、基板１は上述の半田融点温度Ｔ２よりも低い予熱温度Ｔ１まで加熱され、この温度で所定時間保持される。そして予熱の後、温度がさらに上昇して半田融点温度Ｔ２を超えることにより、半田バンプ７が溶融し電極２の上面と半田接合される。ここでは半田バンプ７は、電子部品６を基板１と接続する接続用電極であるとともに、この接続用電極に供給される接合用半田部を兼ねたものとなっている。なお接合用半田部として半田バンプ７を用いる替わりに、電極２に予めプリコート半田を形成し、このプリコート半田によって半田接合を行うようにしてもよい。
【００１５】
この半田接合において、半田バンプ７の表面に生成した酸化膜は酸化膜除去能力を有する樹脂接着材４によって除去されることから、良好な接合性が確保される。またこの加熱により、樹脂接着材４の熱硬化反応が並行して進行するが、樹脂接着材４の熱硬化温度Ｔ３は、半田バンプ７の半田融点温度Ｔ２よりも高いことから、半田バンプ７が溶融した溶融半田が電極２の表面を濡らす際には樹脂接着材４はまだ急速な熱硬化を開始していない状態にある。したがって樹脂接着剤４は未硬化で硬化が不完全な状態であり、樹脂接着材４中における溶融半田の流動が確保され、半田バンプ７と電極２とのセルフアライメントが阻害されることがない。
【００１６】
そして溶融半田が電極２と接合された後、加熱が継続されて温度が上昇する。次いで熱硬化温度Ｔ３を超えて耐熱温度Ｔ４（約２５０℃）よりも低く設定される最高加熱温度Ｔａまで昇温し、この温度が所定時間保持された後に降温過程に移行し、これにより、第１面１ａへの電子部品６の実装が終了する。この加熱過程において、温度が熱硬化温度Ｔ３以上に保持される時間ｔａの間、樹脂接着材４の熱硬化が急速に進行する。この時間ｔａは一般に生産タクトタイムの制約から樹脂接着材４の完全硬化に要する時間よりも短く設定され、したがって第１面への実装完了時点では、樹脂接着材４は熱硬化反応が完全に終了していない半硬化状態にある。
【００１７】
この第１面１ａへの実装に引き続き、第２面１ｂを対象とした実装が行われる。すなわち、図２（ａ）に示すように、第２面１ｂに形成された第２電極である電極３上には、半田接合用ペーストであるクリーム半田８が印刷により供給される（第２ペースト供給工程）。クリーム半田８は、ペースト状のフラックス中に半田粒子を含有させたものであり、半田接合のみを目的とした接合材料であることから、樹脂接着材４に含まれるような熱硬化性性樹脂を含まない構成となっている。
【００１８】
次いで図２（ｂ）に示すように、ペースト供給後の第２面１ｂには、両端部に接続用電極としての端子９ａが設けられた電子部品９が搭載され（第２搭載工程）、これにより端子９ａがクリーム半田８を介して電極３上に着地する。そしてこの後、基板１は第２面１ｂを対象とした第２面リフローのためにリフロー工程に送られ。ここで所定の加熱プロファイルにしたがって加熱される（第２加熱工程）。
【００１９】
この第２面リフローにおける加熱プロファイルは、図３に示すように第１面リフローと同様であり、温度が上昇して半田融点温度Ｔ２を超えることにより、クリーム半田８中の半田成分が溶融しこの溶融半田を介して端子９ａが電極３と半田接合される。ここではクリーム半田８中の半田成分が、電極３に供給される接合用半田部となっている。
【００２０】
またこの加熱により、第１面１ａに既に実装された電子部品６と基板１との間の樹脂接着材４も同時に加熱され、温度が上昇して熱硬化温度Ｔ３に到達することにより、一端中断された樹脂接着材４の急速な熱硬化が再開される。そしてＴａと同様に設定される最高加熱温度Ｔｂまで昇温した後、熱硬化温度Ｔ３に降温するまでの時間ｔｂの間、樹脂接着材４の熱硬化が急速に進行する。
【００２１】
すなわち樹脂接着材４は、第１面１ａを対象としたリフロー時の熱硬化のための時間ｔａに加えて、第２面１ｂを対象としたリフロー時においても、上述の時間ｔｂの間は熱硬化温度Ｔ３以上に保持される。したがって、熱硬化温度Ｔ３が半田融点温度よりも高い熱硬化性樹脂を用いた電子部品の実装を両面実装基板に適用する場合において、熱硬化性樹脂を用いた実装を先に実装対象となる第１面１ａに適用することにより、生産タクトの制約から加熱プロファイルにおいて十分な熱硬化時間を確保することが困難な場合にあっても、第１面１ａ、第２面１ｂを対象としたリフロー過程において極力長い硬化時間を通算して確保することができる。
【００２２】
このため、従来は半田接合のためのリフロー工程を終了した後に別途必要とされた樹脂硬化のための後キュア工程を省略、もしくはキュア時間を短縮することが可能となっている。また、第１面リフローにおいて電極２上面の半田濡れ状態が不十分で接合不良が発生している場合にあっても、この状態では樹脂接着材４が完全に硬化してなく活性力が残留していることから、第２面リフロー時の加熱において接合部の半田が再溶融し、良好な半田接合が行われる。
【００２３】
上記実施の形態に示す実装基板の製造方法は、生産においては次に示すような２通りの態様で適用される。第１の態様は、両面に電子部品が実装される実装基板の設計段階において、実装対象となる電子部品への前述の樹脂接着材４の適用可否を考慮した上で、電子部品の第１面、第２面への振り分けを決定するものである。
【００２４】
すなわち、基板の第１面と第１面の裏側の第２面にそれぞれ電子部品が実装された実装基板を製造する実装基板を設計する際には、部品実装工程において先に実装対象となる第１面を、前述の樹脂接着材４を含む半田接合用ペーストが供給される第１ペースト供給面として予め設定する。そして、基板設計時の電子部品配置において、熱硬化性樹脂を用いた実装方式が適用される電子部品を優先的に第１面に配置する。基板設計時にこのような方針で電子部品配置を行うことにより、先に実装対象となる第１面に樹脂接着材４を用いる電子部品が集中して配置される。したがって使用された樹脂接着材４は必ず２回の熱硬化過程を経ることになる。
【００２５】
これに対し、基板設計段階において上述のような考慮がなされていない基板については、以下のような取り扱いがなされる。まず、両面実装基板の電子部品配置が提示されたならば、基板の表裏各面にそれぞれ実装される電子部品の種類と数量を対比する。そして樹脂接着材４を用いた実装方式が適用可能な電子部品の割合が多い方の面を、部品実装工程において先に実装対象となる第１面に設定し、このような電子部品には樹脂接着材４を用いた実装方式を適用する。そして第１面のその他の電子部品および第２面の電子部品には全てクリーム半田を用いた実装方法など、樹脂接着材４を用いない実装方法を適用する。これにより、先に実装対象となる第１面にのみ、樹脂接着材４を用いる電子部品が配置され、したがって使用された樹脂接着材４は必ず２回の熱硬化過程を経る。
【００２６】
【発明の効果】
本発明によれば、先に実装対象となる第１面のみに熱硬化性樹脂を含む半田接合用ペーストを供給し、この半田接合用ペーストの熱硬化を、第１面を対象とする第１加熱工程と第２面を対象とする第２加熱工程の２回にわたって行うようにしたので、熱硬化を極力促進して後キュア工程を省略またはキュア時間を短縮することができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態の実装基板の製造方法の工程説明図
【図２】本発明の一実施の形態の実装基板の製造方法の工程説明図
【図３】本発明の一実施の形態の実装基板の製造方法における加熱プロファイルを示すグラフ
【符号の説明】
１ 基板
１ａ 第１面
１ｂ 第２面
２、３ 電極
４ 樹脂接着材
６ 電子部品
７ 半田バンプ
８ クリーム半田
９ 電子部品
９ａ 端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mounting board manufacturing method for manufacturing a mounting board by mounting electronic components on the board.
[0002]
[Prior art]
As a method for mounting an electronic component such as a semiconductor chip, a solder bonding method is widely used. As a soldering method, a method in which a thermosetting resin adhesive is applied on the electrodes of the substrate in advance before mounting the components is adopted. In this method, the solder bump of the electronic component is landed on the electrode and then the substrate is heated, so that the solder bonding between the solder bump and the electrode and the thermosetting of the resin adhesive are performed in the same heating process. This method has an advantage that it is not necessary to provide the reinforcing underfill resin forming step as an independent step.
[0003]
[Problems to be solved by the invention]
However, the following inconvenience may occur in the mounting process of the electronic component using the resin adhesive. The resin adhesive applied as described above is thermally cured by heating at the time of reflow for solder bonding, but generally the resin is held at a temperature higher than the thermosetting temperature in the heating profile for solder bonding. In many cases, the heating time during reflow is not sufficient for complete curing of the resin. For this reason, conventionally, a curing process aimed at completing the resin curing is often separately provided after reflow. In this curing step, heating for a long time is required.
[0004]
Therefore, the present invention provides a mounting substrate that can improve productivity by omitting a post-curing step for completely curing the resin or shortening a curing time in manufacturing a mounting substrate using a resin adhesive. It aims to provide a method.
[0005]
[Means for Solving the Problems]
The method of manufacturing a mounting board according to claim 1 is a manufacturing method of a mounting board for manufacturing a mounting board in which electronic components are respectively mounted on a first surface of the substrate and a second surface on the back side of the first surface. the first surface of the previously mounting object in the mounting step, the first solder bonding paste containing a thermosetting resin having a thermosetting temperature higher than the melting point of the solder temperature used has implement activating action a first paste supplying step of supplying covers the first electrode provided on a surface, by mounting an electronic component solder bumps are provided on the first surface after the paste supplied to the solder bumps first surface of the electronic component a first mounting step of landing a first electrode provided, the thermosetting resin with the solder bumps by heating the substrate after the first mounting step to melt the solder bumps soldered to the first electrode A first heating step for starting thermosetting of A second paste supplying step of supplying a solder paste is a solder bonding paste not including the thermosetting resin on the second surface of the substrate mounting has been completed on the first surface, the electronic components on the second surface after the paste supply And mounting the connection electrode of the electronic component on the second electrode provided on the second surface, and heating the substrate after the second mounting step to connect the connection electrode to the second electrode. look including a second heating step of resuming the thermosetting of the thermosetting resin of the first surface as well as solder bonded to the electrode, solder fluidity melt in the thermosetting resin is ensured in the first heating step In addition, the self-alignment between the solder bump and the first electrode is not hindered .
[0008]
According to the present invention, the solder bonding paste containing the thermosetting resin is supplied only to the first surface to be mounted first, and the solder bonding paste is first cured for the first surface. By performing the heating process and the second heating process for the second surface twice, the thermal curing can be accelerated as much as possible, and the post-curing process can be omitted or the curing time can be shortened.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are process explanatory views of a mounting substrate manufacturing method according to an embodiment of the present invention, and FIG. 3 is a graph showing a temperature profile of a reflow process in the mounting substrate manufacturing method according to an embodiment of the present invention. is there. In this embodiment, a process of manufacturing a mounting substrate by mounting electronic components on a substrate having electrodes formed on both sides by solder bonding is shown.
[0010]
In FIG. 1A, reference numeral 1 denotes a substrate for double-sided mounting. On the first surface 1a (upper surface in FIG. 1) of the substrate 1 and the second surface 1b on the back side of the first surface (lower surface in FIG. 1), An electrode 2 as a first electrode and an electrode 3 as a second electrode are formed. The first surface 1a is a surface to be mounted first in the process of manufacturing a mounting substrate by mounting electronic components on both front and back surfaces of the substrate 1.
[0011]
As shown in FIG. 1B, a resin adhesive 4 as a solder bonding paste is supplied around the electrode 2 on the first surface 1a so as to cover the electrode 2 with a dispenser 5 (first paste supplying step). ). The resin adhesive 4 is an adhesive function that seals and reinforces the lower surface of the electronic component by adding an active component having an ability to remove an oxide film to a base mainly composed of a thermosetting resin such as an epoxy resin. In addition to this, the oxide film on the surface of the solder is removed at the time of soldering to serve as a flux that improves solderability. Since this resin adhesive 4 removes the oxide film on the surface of the solder bump with the active component contained therein, there is no need to separately apply a flux, and the cleaning process after reflow required in the conventional method using the flux is omitted. It has the advantage of being able to.
[0012]
Here, the base has a thermosetting temperature higher than the melting point of the solder used for mounting. The solder melting point temperature is 183 ° C. for Sn / Pb solder and 220 ° C. for Sn / Ag solder. In addition, the thermosetting temperature as used in this Embodiment is the temperature calculated | required by the differential scanning calorimetry (DSC) used for the measurement of the hardening reaction of a resin material. That is, if the relationship between the amount of heat and temperature obtained in the process of heating a 10 mg sample at a temperature rising rate of 10 ° C./min is plotted and plotted with the amount of heat on the vertical axis and the temperature on the horizontal axis, Is formed. Then, a tangent line is drawn from the inflection point on the slope on the high temperature side of this mountain-shaped curve, and the temperature at which this tangent line intersects the horizontal axis is determined as the thermosetting temperature.
[0013]
Next, as shown in FIG. 1C, on the first surface 1a after supplying the paste, an electronic component 6 having solder bumps 7 as connection electrodes provided on the lower surface is mounted (first mounting step). Thus, the solder bump 7 is landed on the electrode 2 through the resin adhesive 4. Thereafter, the substrate 1 is sent to the reflow process for the first surface reflow intended for the first surface 1a. Here, heating is performed according to a predetermined heating profile (first heating step).
[0014]
The heating profile in the first surface reflow will be described with reference to FIG. When heating is started, the substrate 1 is heated to a preheating temperature T1 lower than the above-described solder melting point temperature T2, and held at this temperature for a predetermined time. After preheating, the temperature further rises and exceeds the solder melting point temperature T2, whereby the solder bump 7 is melted and soldered to the upper surface of the electrode 2. Here, the solder bump 7 serves as a connection electrode for connecting the electronic component 6 to the substrate 1 and also serves as a bonding solder portion supplied to the connection electrode. Instead of using the solder bumps 7 as the bonding solder portions, precoat solder may be formed in advance on the electrodes 2 and solder bonding may be performed using the precoat solder.
[0015]
In this solder bonding, the oxide film generated on the surface of the solder bump 7 is removed by the resin adhesive 4 having an oxide film removal capability, so that good bondability is ensured. In addition, the heat curing reaction of the resin adhesive 4 proceeds in parallel with this heating. However, since the thermosetting temperature T3 of the resin adhesive 4 is higher than the solder melting temperature T2 of the solder bump 7, the solder bump 7 When the molten solder that has melted wets the surface of the electrode 2, the resin adhesive 4 has not yet started rapid thermal curing. Accordingly, the resin adhesive 4 is uncured and incompletely cured, the flow of molten solder in the resin adhesive 4 is ensured, and self-alignment between the solder bumps 7 and the electrodes 2 is not hindered.
[0016]
After the molten solder is joined to the electrode 2, heating is continued and the temperature rises. Next, the temperature is raised to a maximum heating temperature Ta that is set lower than the heat-resistant temperature T4 (about 250 ° C.) over the thermosetting temperature T3, and after this temperature is maintained for a predetermined time, the temperature lowering process is started. The mounting of the electronic component 6 on the first surface 1a is completed. In this heating process, the thermosetting of the resin adhesive 4 proceeds rapidly during the time ta during which the temperature is maintained at the thermosetting temperature T3 or higher. This time ta is generally set to be shorter than the time required for complete curing of the resin adhesive 4 due to production tact time restrictions. Therefore, when the mounting on the first surface is completed, the resin adhesive 4 completely completes the thermosetting reaction. It is not semi-cured.
[0017]
Subsequent to mounting on the first surface 1a, mounting on the second surface 1b is performed. That is, as shown in FIG. 2A, the cream solder 8 that is a solder bonding paste is supplied by printing on the electrode 3 that is the second electrode formed on the second surface 1b (second paste). Supply process). Since the cream solder 8 is a paste material containing solder particles in a paste-like flux and is a bonding material only for solder bonding, a thermosetting resin contained in the resin adhesive 4 is used. It does not include.
[0018]
Next, as shown in FIG. 2B, on the second surface 1b after supplying the paste, electronic components 9 having terminals 9a serving as connection electrodes at both ends are mounted (second mounting step). As a result, the terminal 9 a is landed on the electrode 3 through the cream solder 8. Thereafter, the substrate 1 is sent to the reflow process for the second surface reflow intended for the second surface 1b. Here, heating is performed according to a predetermined heating profile (second heating step).
[0019]
The heating profile in the second surface reflow is the same as that in the first surface reflow as shown in FIG. 3, and when the temperature rises and exceeds the solder melting point temperature T2, the solder component in the cream solder 8 is melted. The terminal 9a is soldered to the electrode 3 via molten solder. Here, the solder component in the cream solder 8 is a bonding solder portion supplied to the electrode 3.
[0020]
Also, by this heating, the resin adhesive 4 between the electronic component 6 already mounted on the first surface 1a and the substrate 1 is also heated at the same time, and the temperature rises to reach the thermosetting temperature T3, thereby interrupting the end. The rapid thermal curing of the resin adhesive material 4 is resumed. Then, after the temperature is raised to the maximum heating temperature Tb set in the same manner as Ta, the thermosetting of the resin adhesive 4 proceeds rapidly for the time tb until the temperature is lowered to the thermosetting temperature T3.
[0021]
That is, the resin adhesive 4 is heated during the above-described time tb during reflow for the second surface 1b in addition to the time ta for thermosetting during reflow for the first surface 1a. It is kept at the curing temperature T3 or higher. Therefore, in the case where the mounting of the electronic component using the thermosetting resin having the thermosetting temperature T3 higher than the solder melting point temperature is applied to the double-sided mounting substrate, the mounting using the thermosetting resin is the first mounting target. Even if it is difficult to secure a sufficient thermosetting time in the heating profile due to restrictions on production tact by applying to the first surface 1a, the reflow process for the first surface 1a and the second surface 1b In this case, it is possible to secure the total curing time as long as possible.
[0022]
For this reason, it is possible to omit the post-curing process for resin curing, which is conventionally required after the reflow process for solder bonding, or to shorten the curing time. Further, even when the solder wet state on the upper surface of the electrode 2 is insufficient due to the first surface reflow and the bonding failure occurs, the resin adhesive 4 is not completely cured in this state and the active force remains. Therefore, the solder at the joint is re-melted by heating at the time of reflowing the second surface, and good solder joint is performed.
[0023]
The manufacturing method of the mounting substrate described in the above embodiment is applied in the following two ways in production. In the first aspect, in the design stage of the mounting substrate on which the electronic components are mounted on both sides, the first surface of the electronic component is taken into consideration in consideration of the applicability of the resin adhesive 4 to the electronic component to be mounted. The distribution to the second surface is determined.
[0024]
That is, when designing a mounting board for manufacturing a mounting board in which electronic components are mounted on the first surface of the substrate and the second surface on the back side of the first surface, the first mounting target in the component mounting process is first. One surface is set in advance as a first paste supply surface to which a soldering paste including the resin adhesive 4 is supplied. And in the electronic component arrangement | positioning at the time of board design, the electronic component to which the mounting system using a thermosetting resin is applied is preferentially arrange | positioned on the 1st surface. By arranging electronic components according to such a policy when designing a board, electronic components using the resin adhesive 4 are concentratedly arranged on the first surface to be mounted first. Therefore, the used resin adhesive 4 always goes through two thermosetting processes.
[0025]
On the other hand, the following handling is performed about the board | substrate which is not considered as mentioned above in the board | substrate design stage. First, when the electronic component arrangement of the double-sided mounting board is presented, the type and quantity of the electronic parts mounted on the front and back surfaces of the board are compared. Then, the surface with the higher proportion of electronic components to which the mounting method using the resin adhesive 4 can be applied is set as the first surface to be mounted first in the component mounting process. A mounting method using the adhesive 4 is applied. A mounting method that does not use the resin adhesive 4 such as a mounting method using cream solder is applied to the other electronic components on the first surface and the electronic components on the second surface. Thereby, the electronic component using the resin adhesive 4 is disposed only on the first surface to be mounted first, and thus the used resin adhesive 4 always undergoes two thermosetting processes.
[0026]
【The invention's effect】
According to the present invention, the solder bonding paste containing the thermosetting resin is supplied only to the first surface to be mounted first, and the solder bonding paste is first cured for the first surface. Since the heating process and the second heating process for the second surface are performed twice, thermosetting can be promoted as much as possible, and the post-curing process can be omitted or the curing time can be shortened.
[Brief description of the drawings]
FIG. 1 is a process explanatory diagram of a mounting substrate manufacturing method according to an embodiment of the present invention. FIG. 2 is a process explanatory diagram of a mounting substrate manufacturing method according to an embodiment of the present invention. Graph showing heating profile in manufacturing method of mounting substrate according to embodiment
DESCRIPTION OF SYMBOLS 1 Board | substrate 1a 1st surface 1b 2nd surface 2, 3 Electrode 4 Resin adhesive 6 Electronic component 7 Solder bump 8 Cream solder 9 Electronic component 9a Terminal

Claims (1)

基板の第１面と第１面の裏側の第２面にそれぞれ電子部品が実装された実装基板を製造する実装基板の製造方法であって、部品実装工程において先に実装対象となる第１面に、活性作用を有し実装に使用される半田の融点温度よりも高い熱硬化温度を有する熱硬化性樹脂を含む半田接合用ペーストを前記第１面に設けられた第１電極を覆って供給する第１ペースト供給工程と、ペースト供給後の第１面に半田バンプが設けられた電子部品を搭載して電子部品の半田バンプを第１面に設けられた第１電極に着地させる第１搭載工程と、第１搭載工程後の前記基板を加熱して前記半田バンプを溶融させて半田バンプを第１電極に半田接合するとともに前記熱硬化性樹脂の熱硬化を開始させる第１加熱工程と、第１面の実装が完了した基板の第２面に前記熱硬化性樹脂を含まない半田接合用ペーストであるクリーム半田を供給する第２ペースト供給工程と、ペースト供給後の第２面に電子部品を搭載して電子部品の接続用電極を前記第２面に設けられた第２電極に着地させる第２搭載工程と、第２搭載工程後の前記基板を加熱して前記接続用電極を第２電極に半田接合するとともに前記第１面の熱硬化性樹脂の熱硬化を再開させる第２加熱工程とを含み、
前記第１加熱工程において前記熱硬化性樹脂中における溶融半田の流動性が確保され、前記半田バンプと第１電極とのセルフアライメントが阻害されないことを特徴とする実装基板の製造方法。A mounting substrate manufacturing method for manufacturing a mounting substrate in which electronic components are respectively mounted on a first surface of a substrate and a second surface on the back side of the first surface, the first surface being a mounting target first in the component mounting step And supplying a solder bonding paste including a thermosetting resin having an active action and a thermosetting temperature higher than the melting point temperature of the solder used for mounting, covering the first electrode provided on the first surface. A first paste supplying step, and an electronic component on which a solder bump is provided on the first surface after supplying the paste, and the solder bump of the electronic component is landed on the first electrode provided on the first surface A first heating step of heating the substrate after the first mounting step to melt the solder bump and soldering the solder bump to the first electrode and starting thermosetting of the thermosetting resin; The second surface of the substrate on which the first surface has been mounted A second paste supplying step of supplying cream solder, which is a solder bonding paste not containing the thermosetting resin, and mounting the electronic component on the second surface after supplying the paste to connect the electrode for connecting the electronic component to the second A second mounting step for landing on a second electrode provided on the surface; heating the substrate after the second mounting step to solder-join the connection electrode to the second electrode; and thermosetting the first surface A second heating step for resuming thermosetting of the resin,
A mounting substrate manufacturing method, wherein fluidity of molten solder in the thermosetting resin is ensured in the first heating step, and self-alignment between the solder bump and the first electrode is not hindered.
JP2002203809A 2002-07-12 2002-07-12 Mounting board manufacturing method Expired - Fee Related JP4200273B2 (en)

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