JP2004343378A

JP2004343378A - Surface acoustic wave device and its manufacturing method

Info

Publication number: JP2004343378A
Application number: JP2003136822A
Authority: JP
Inventors: Yasuhide Onozawa; 康秀小野澤; Tatsuya Anzai; 達也安齋
Original assignee: Toyo Communication Equipment Co Ltd
Current assignee: Toyo Communication Equipment Co Ltd
Priority date: 2003-05-15
Filing date: 2003-05-15
Publication date: 2004-12-02
Anticipated expiration: 2023-05-15
Also published as: JP3912324B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an SAW device for which void generation and resin intrusion to an airtight space are prevented at the time of laminating resin in the SAW device in which the airtight space is formed below an IDT by coating the outer surface of an SAW chip mounted on a mounting substrate base material with a heated and softened resin sheet and filling the resin in a skirt part of the SAW chip, and provide its manufacturing method. <P>SOLUTION: A frame body overlapping with the peripheral edge part of the surface acoustic wave chip is formed on the upper surface of the mounting substrate, the frame body is thinner than a gap between the surface acoustic wave chip and the mounting substrate, and the frame body is formed so as to cover the dicing cut margin of the mounting substrate base material along the dicing cut margin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、弾性表面波デバイスに関し、特にパッケージサイズを小型化にした弾性表面波デバイスとその製造方法に関する。
【０００２】
【従来の技術】
近年、弾性表面波（ＳｕｒｆａｃｅＡｃｏｕｓｔｉｃＷａｖｅ：以下、ＳＡＷ）デバイスは移動体通信分野で幅広く用いられ、高性能、小型、量産性等の点で優れた特徴を有することから特に携帯電話等に多く用いられている。また、半導体部品においてＣＳＰ（ＣｈｉｐＳｉｚｅＰａｃｋａｇｅ）と呼ばれる小型パッケージングが一般化するのに伴って、ＳＡＷデバイスにおいてのフィルタの小型化の容易化とバッチ式の製造方法による生産性の向上という観点から、ＣＳＰ技術を用いた生産方法が導入されるようになっている。
【０００３】
前述したＣＳＰ技術を用いた生産方法において、本願発明者が特願２００２−２９３１１０号にてラミネート工程、プレス成形工程、後硬化工程の３つの工程からなるＳＡＷデバイスの樹脂封止工程を提案している。以下、図８から図１２に基づいて前記樹脂封止工程を詳細に説明する。図８は、実装基板母材１４０上にＳＡＷチップ１１５をフリップチップ実装する工程を示す断面図である。実装基板母材１４０は、絶縁基板１０３の底部に外部電極１０４を上部に配線パターン１０５を備え、内部に外部電極１０４と配線パターン１０５とを導通する内部導体１０６を備え、ＳＡＷチップ１１５は圧電基板１１８の主面上にＳＡＷを励振する為のＩＤＴ１１７と該ＩＤＴ１１７に導通した接続パッド１１６を備えている。そして、実装基板母材１４０の配線パターン１０５上にＳＡＷチップ１１５の接続パッド１１６を、導体バンプ１１０を用いて接続することによりフリップチップ実装が行われる。
【０００４】
次に、図９に示すように、図８の実装基板母材１４０上に実装した複数のＳＡＷチップ１１５の圧電基板１１８の上面に跨るように、樹脂シート１３０を載置する。この樹脂シート１３０は、樹脂シート本体１３１の一方の面に離型性を有する保護フィルム１３２を剥離可能に貼付している。
【０００５】
次に、図１０は各ＳＡＷチップ１１５上に載置された樹脂シート１３０を、ラミネート装置１５０によりＳＡＷチップ１１５に対してラミネートする熱ローララミネート工程を示した断面図である。熱ローララミネート工程を実施するためのラミネート装置１５０は、ＳＡＷチップ１１５を搭載した実装基板母材１４０を矢印で示す方向へ所定のラミネート速度で移動させる移動手段と、ＳＡＷチップ１１５上の樹脂シート１３０の上面に圧接して矢印方向へ回転駆動される熱ローラとしての押圧ローラ１５１と、実装基板母材１４０の下面を支持して押圧ローラ１５１との間で加圧力を発生するガイド部材としての支持ローラ１５２とを備えている。押圧ローラ１５１は、ヒータにより所要温度に加熱制御されると共に、駆動源により実装基板母材１４０をラミネート方向へ送るように回転駆動される。そして、支持ローラ１５２は、矢印方向へ連れ回り、或いは回転駆動される。この熱ローララミネート工程では、以下の条件を満たすことが求められる。
（ａ）押圧ローラ１５１の加熱温度を樹脂シート１３０の軟化（又は溶融）温度以上、且つ硬化温度未満に設定すること。
（ｂ）押圧ローラ１５１によって樹脂シート１３０を押圧ローラ１５１にて加熱しながら加圧することにより軟化（又は溶融）させること。
（ｃ）軟化（又は溶融）した樹脂シート１３０を押圧ローラ１５１にて加熱しながら加圧することによって、樹脂シート本体１３１をＳＡＷチップの谷間に充填、浸透させて、気密空間Ｓを保持しながらＳＡＷチップ１１５を樹脂にて被覆すること。
複数のＳＡＷチップ１１５上に跨って載置された樹脂シート１３０を、図１０に示した熱ローララミネート工程により、その樹脂シート１３０が、ＳＡＷチップ１１５外面から実装基板母材１４０上面にかけて充填されることによりラミネートする。なお、熱ローララミネート法においては、ＳＡＷチップ１１５と実装基板母材１４０との間の気密空間Ｓが必要以上に拡張されないよう、樹脂シート１３０の一端側から他端側へ向けて順次加圧してエアーを抜きながらラミネートできる利点がある。
【０００６】
ラミネート工程だけでは樹脂シート１３０の硬化は完了しないので、樹脂にて外面をラミネートしたＳＡＷチップを加圧しながら加熱することにより、気密空間Ｓ内の気体の膨張を抑制しながら樹脂を硬化させるプレス成形工程を行い、更に樹脂を完全に硬化させる為に雰囲気温度を樹脂硬化温度に設定した恒温槽中に実装基板母材を配置し加熱する後硬化工程を行う。以上の工程が完了した状態が図１１である。そして、保護フィルム１３２を剥離し図１１に示されているダイシング切り代に沿って実装基板母材１４０をダイシングブレードにてダイシングすることにより図１２のような個片のＳＡＷデバイス１００が完成する。
【０００７】
【発明が解決しようとする課題】
しかしながら、前述したようなラミネート工程、プレス成形工程、後硬化工程の３つの工程からなるＳＡＷデバイスの樹脂封止工程において、ラミネート工程でのエアーの膨張（ボイド）の発生や気密空間Ｓへの樹脂侵入が問題となっている。この問題は、樹脂シートの厚さを実装基板母材の中央部のＳＡＷチップにて最適となるように設定すると、実装基板母材の最外周部に配置されているＳＡＷチップにおいて、図１３のＳＡＷデバイス１０１に示すようなダイシング切り代に到達してしまう程の著しいボイドが発生してしまい、逆に樹脂シートの厚さを実装基板母材の最外周部に配置されているＳＡＷチップにて最適となるように設定すると、実装基板母材の中央部のＳＡＷチップにて気密空間Ｓへの樹脂侵入が発生してしまう。即ち、実装基板母材の中央部と最外周部とで封止樹脂の侵入状態にばらつきが生じてしまうという問題が発生する。
【０００８】
そこで、上記問題を解決する為に、特開平１１−２１４９５５号公報や特開２０００−２６１１７７号公報（以下、これらを先行技術１と称す）にて開示されているキャビティー型実装基板の適用を検討した。図１４は、先行技術１にて開示されているキャビティー型実装基板を用いたＳＡＷデバイスの断面図を示したものである。圧電基板２０２の主面上にＩＤＴ２０３と該ＩＤＴ２０３に導通した接続パッド２０４を設けたＳＡＷチップ２０１と、ガラスセラミックスやアルミナからなる基体２０５ａ、及び基体２０５ａと同様な部材で構成されＳＡＷチップ２０１の周縁外周部を載置する環状の積層部材２０５ｂ、及び基体２０５ａと同様な部材で積層部材２０５ｂより広い空間を形成する環状の枠体２０５ｃから構成され、基体２０５ａの上面に実装用パッド２０７を設けた実装基板２０５を備えており、ＳＡＷチップ２０１上に設けた接続パッド２０４と実装基板２０５の基体２０５ａに設けた実装用パッド２０７とを金属バンプ２１０を介して導通固着し、圧電基板２０２の上面及び側面を完全に封止樹脂２１１で覆った構造である。
【０００９】
前記先行技術１に記載されているキャビティー型実装基板においては、溶融して液化した樹脂をキャビティ内に充填し硬化して封止樹脂としているが、このキャビティ型実装基板に上述したラミネート方式を採用した場合を検討する。図１４から明らかなように、ＳＡＷチップ２０１外周部に配置されている枠体２０５ｃがＳＡＷチップ２０１の上面よりも高くなっている為、樹脂２１１をラミネートした際にエアーの逃げ場がなくなりボイドが発生しやすいという欠点を有する。従来技術で説明したように、ラミネート工程においてボイド発生を防止する為に余分なエアーを抜きながらラミネートする必要があり、先行技術１に記載のキャビティ型実装基板を用いてラミネート工程を行うと余分なエアーを抜きながらのラミネートが困難となる。
【００１０】
次に特開平１０−２２７６３号公報（以下、先行技術２と称す）にて開示されている微小エアギャップ構造へのラミネート工程の適用を検討した。図１５は先行技術２に記載されている微小エアギャップ構造のＳＡＷデバイスの縦断面図を示したものである。圧電基板３０２の主面上にＩＤＴ３０３及び該ＩＤＴ３０３に導通された接続パッド３０４を配置したＳＡＷチップ３０１と、表面に実装用パッド３０６及び該実装用パッド３０６の部分にホールを設けた絶縁層３０７を形成した実装基板３０５を備えており、ＳＡＷチップ３０１に設けた接続パッド３０４と、実装基板３０５に設けた実装用パッド３０６とを金属バンプ３１０にてフリップチップ実装した後、封止剤３１１で封止しエアギャップ３２０を設けた構造である。先行技術２の特徴としては、実装基板３０５とＳＡＷチップ３０１との間に絶縁層３０７を設けることによって、ＳＡＷチップ３０１と実装基板３０５との間隙を限りなく零に近づけ、封止剤３１１がエアギャップ３２０へ流れ込まないようにしたことである。
【００１１】
前記先行技術２は、ＳＡＷチップと実装基板との間の気密空間を微小ギャップとすることで封止樹脂が気密空間に浸入しにくくなるという効果が期待できる。しかしながら、先行技術２記載のＳＡＷデバイスの構造は、実装基板３０５上に絶縁層３０７を形成した上で、実装用パッド３０６の部分にホールを形成する工程が必要となるが、デバイスの小型化に伴ない、実装用パッド３０６の面積も微小となるので実装用パッド３０６とホールとの位置合わせには精度の高い厳密な作業が必要となり煩雑であった。更に、絶縁層３０７上に設けたホールが極めて微小であるため、実装基板３０５に金属バンプ３１０を形成する際にも煩雑な作業が要求されるといった製造上の問題がある。
【００１２】
本発明は、以上の問題を解決するためになされたものであり、ＳＡＷチップを実装基板母材にフリップチップ実装し表面を樹脂で封止したＳＡＷデバイスにおいて、容易に気密空間を形成し、且つ、樹脂をラミネートする際にボイド発生や気密空間への樹脂浸入を防いだＳＡＷデバイス及びその製造方法を提供することを目的とする。
【００１３】
【課題を解決するための手段】
上記目的を達成するために本発明に係るＳＡＷデバイスとその製造方法の請求項１記載の発明は、弾性表面波チップと、上面に前記弾性表面波チップをフリップチップ実装した実装基板と、前記弾性表面波チップに形成されたＩＤＴと前記実装基板との間に気密空間を形成しつつ前記弾性表面波チップの外面と前記実装基板の上面とを覆う封止樹脂とを備えた弾性表面波チップであって、前記実装基板の上面には前記弾性表面波チップの周縁部と重複する枠体が形成されており、該枠体は前記弾性表面波チップと前記実装基板との間隙よりも薄い厚みを有することを特徴とする弾性表面波デバイスである。
【００１４】
請求項２記載の発明は、前記枠体（第一の枠体）の上面に第二の枠体を積層したものであって、該第二の枠体と第一の枠体とを合わせた厚みが前記弾性表面波チップの上面よりも低いことを特徴とする弾性表面波デバイスである。
【００１５】
請求項３記載の発明は、複数の実装基板を複数個シート状に連結した実装基板母材のダイシング切り代に沿って該ダイシング切り代を覆うように枠体を形成する枠形成工程と、弾性表面波チップを前記実装基板母材に導体バンプを用いてフリップチップ実装する工程と、前記実装基板母材に実装した弾性表面波チップの上面に樹脂シートを載置する工程と、実装基板の一端から他端に向けて前記樹脂シートを軟化又は溶融させながら加圧することにより前記弾性表面波チップの外面を樹脂にて覆うラミネート工程と、ラミネートした前記樹脂を加圧しながら加熱硬化させるプレス成形工程と、前記ダイシング切り代に沿って前記弾性表面波チップを個片に切り分ける切断工程とを備えていることを特徴とする弾性表面波デバイスの製造方法である。
【００１６】
請求項４記載の発明は、前記枠体形成工程において、前記枠体が弾性表面波チップの周縁部と重複し、且つ、フリップチップ実装した弾性表面波チップと実装基板母材との間隙よりも薄い厚みを有するように形成することを特徴とする請求項３記載の弾性表面波デバイスの製造方法である。
【００１７】
請求項５記載の発明は、前記枠体形成工程において、前記枠体（第一の枠体）の上面に第二の枠体を積層し、該第二の枠体は各辺の幅は第一の枠体よりも小さく、且つ、第一の枠体と第二の枠体とを合わせた厚みが前記弾性表面波チップの上面よりも低くなるように形成することを特徴とする請求項３及び４に記載の弾性表面波デバイスの製造方法である。
【００１８】
請求項６記載の発明は、前記ラミネート工程時の樹脂シートの厚みｔｒが、
Ｌ／｛（Ｘ＋Ｇｘ）（Ｙ＋Ｇｙ）｝≦ｔｒ
但し、Ｌ＝（Ｘ＋Ｇｘ）（Ｙ＋Ｇｙ）（Ｈ＋Ｔ＋Ａ）−ＸＹＴ−ＸＹＡ−｛ＸＶｙＡ＋ＹＶｘＡ＋（４ＶｘＶｙＡ）／３｝
（Ｌ：一つの弾性表面波チップ外面を封止するのに必要な樹脂シートの体積、Ｘ：弾性表面波チップの一辺の長さ、Ｙ：弾性表面波チップの他辺の長さ、Ｇｘ：Ｘ方向に隣接し合う弾性表面波チップの間隔、Ｖｘ：Ｙ方向へ延びるダイシング切り代から直近の弾性表面波チップ側面までの距離、Ｇｙ：Ｙ方向に隣接し合う弾性表面波チップ間の間隔、Ｖｙ：Ｘ方向へ延びるダイシング切り代から直近の弾性表面波チップ側面までの距離、Ｈ：一つの弾性表面波チップ外面を樹脂シートにて被覆完了した後の弾性表面波チップ上面に位置する樹脂の厚さ、Ｔ：圧電基板の厚さ、Ａ：実装基板母材上面から圧電基板底面までの間隔）であることを特徴とする請求項３乃至５のいずれかに記載の弾性表面波デバイスの製造方法である。
【００１９】
請求項７記載の発明は、前記ラミネート工程は、前記樹脂シートに圧接しながら回転する所定温度に加熱した押圧ローラと前記実装基板母材下面に添設したガイド部材との間で実装基板母材及び弾性表面波チップを加圧する熱ローララミネート工程からなり、前記熱ローララミネート工程は、押圧ローラの加熱温度を樹脂シートの軟化温度又は溶融温度以上、且つ硬化温度未満に設定し、前記押圧ローラによって前記樹脂シート上面を加熱しながら加圧することにより軟化又は溶融させ、軟化又は溶融した樹脂シートを押圧ローラにて加熱しながら加圧することによって気密空間を確保しながら弾性表面波チップを樹脂にて被覆することを特徴とする請求項３乃至６のいずれかに記載の弾性表面波フィルタの製造方法である。
【００２０】
請求項８記載の発明は、前記ラミネート工程は、前記樹脂シート上面に先端で圧接しながら一方向へ移動する所定温度に加熱したブレードと、前記実装基板母材下面に添設したガイド部材との間で実装基板母材及び弾性表面波チップを加圧するブレードラミネート工程からなり、前記ブレードラミネート工程は、ブレードの加熱温度を樹脂シートの軟化温度又は溶融温度以上、且つ硬化温度未満に設定し、ブレードによって樹脂シートの上面を加熱しながら加圧することにより軟化又は溶融させ、軟化又は溶融した樹脂シートをブレードにて加熱しながら加圧することによって気密空間を確保しながら弾性表面波チップを樹脂にて被覆することを特徴とする請求項３乃至６のいずれかに記載の弾性表面波フィルタの製造方法である。
【００２１】
請求項９記載の発明は、前記ラミネート工程は、減圧雰囲気にて実施することを特徴とする請求項３乃至８のいずれかに記載の弾性表面波デバイスの製造方法である。
【００２２】
請求項１０記載の発明は、前記ラミネート工程は、不活性ガス雰囲気中にて実施することを特徴とする請求項３乃至８のいずれかに記載の弾性表面波デバイスの製造方法である。
【００２３】
請求項１１記載の発明は、前記プレス成形工程は、前記実装基板母材の下面側に接する第一のプレート治具と前記実装基板母材上面の樹脂シートに接する第二のプレート治具との間に前記実装基板母材を挟んだ状態で加圧しながら加熱硬化するものであって、前記第二のプレート治具の下面には、前記樹脂シート周縁部を前記実装基板母材上面に押さえつけるための押さえフレームが形成されていることを特徴とする請求項３乃至１０のいずれかに記載の弾性表面波デバイスの製造方法である。
【００２４】
請求項１２記載の発明は、前記プレス成形工程は、前記第一のプレート治具の上面には、前記第二のプレート治具の下面と当節して両者の間隙を制限するためのスペーサ部材が形成されていることを特徴とする請求項１２に記載の弾性表面波フィルタの製造方法である。
【００２５】
【発明の実施の形態】
以下、本発明を図面に示した実施の形態により詳細に説明する。図１から図５は本発明の第一の実施例に係るＳＡＷデバイスの製造方法について示したものである。まず、図１（ａ）及び（ｂ）は実装基板２をシート状に連結した構造の複数個の実装基板母材２にＳＡＷチップ１５をフリップチップ実装する工程を示す平面図、及び断面図である。実装基板２は、絶縁基板３の底部に表面実装用の外部電極４を、上部にＳＡＷチップ１５と導通をとる為の配線パターン５を備え、内部に外部電極４と配線パターン５を導通する内部導体６を備えている。また、ＳＡＷチップ１５は圧電基板１８の主面上にＳＡＷを励振するためのＩＤＴ１７と該ＩＤＴ１７と導通した接続パッド１６を備えている。そして、実装基板２上の配線パターン５とＳＡＷチップ１５上の接続パッド１６とを導体バンプ１０を用いて接続することによりフリップチップ実装を行う。本発明の特徴としては、図１に示すように実装基板母材４０の各個片ＳＡＷチップの周囲に枠体２０を設けたことである。ここで前記枠体２０は以下の全ての条件を満たすように設置されている。
（ａ）枠体２０は、ＳＡＷチップ１５と実装基板母材４０との間の空間Ｓの外周に設けられ、実装基板母材４０上面から圧電基板１８底面までの間隙よりも小さい厚みであること。
（ｂ）枠体２０の各辺の幅は、ダイシング切り代Ｄより大きいこと。
（ｃ）枠体２０は、ダイシング切り代Ｄを覆うように実装基板母材４０上に設けられていること。
（ｄ）枠体２０の少なくとも一部が圧電基板１８と実装基板母材４０上との間に挟まれていること。即ち、ＳＡＷチップ１５の周縁部と重複するように枠体２０を設定すること。
【００２６】
次に、図２に示すように、図１の実装基板母材４０上に実装した複数のＳＡＷチップ１５の上面を跨るように樹脂シート３０を載置する。この樹脂シート３０は、樹脂シート本体３１の一方の面に離型性を有する保護フィルム３２を剥離可能に貼付している。
【００２７】
ここで、樹脂シート本体３１の厚みをｔｒとすると、ｔｒを以下の条件で設定する。
Ｌ／｛（Ｘ＋Ｇｘ）（Ｙ＋Ｇｙ）｝≦ｔｒ
但し、Ｌ＝（Ｘ＋Ｇｘ）（Ｙ＋Ｇｙ）（Ｈ＋Ｔ＋Ａ）−ＸＹＴ−ＸＹＡ−｛ＸＶｙＡ＋ＹＶｘＡ＋（４ＶｘＶｙＡ）／３｝
（Ｌ：一つのＳＡＷチップ外面を封止するのに必要な樹脂シートの体積、Ｘ：ＳＡＷチップの一辺の長さ、Ｙ：ＳＡＷチップの他辺の長さ、Ｇｘ：Ｘ方向に隣接し合うＳＡＷチップの間隔、Ｖｘ：Ｙ方向へ延びるダイシング切り代から直近のＳＡＷチップ側面までの距離、Ｇｙ：Ｙ方向に隣接し合うＳＡＷチップ間の間隔、Ｖｙ：Ｘ方向へ延びるダイシング切り代から直近のＳＡＷチップ側面までの距離、Ｈ：一つのＳＡＷチップ外面を樹脂シートにて被覆完了した後のＳＡＷチップ上面に位置する樹脂の厚さ、Ｔ：圧電基板の厚さ、Ａ：実装基板母材上面から圧電基板底面までの間隔）
以上のように、樹脂シート本体３１の厚みを設定することで、後にＳＡＷデバイスに樹脂をラミネートした際に、樹脂の厚みが不足し気密空間Ｓに穴が空いてＳＡＷデバイスの防塵・防湿性を低下させてしまう虞がなくなる。
【００２８】
樹脂シート３０をＳＡＷチップ１５上に載置後、図３に示すようにラミネート工程を行う。なお、本実施例においては従来技術と同様に熱ローララミネート方法を用いた例について説明する。熱ローララミネート工程を実施するためのラミネート装置５０は、ＳＡＷチップ１５を搭載した実装基板母材４０を矢印で示す方向へ所定のラミネート速度で移動させる移動手段と、ＳＡＷチップ１５上の樹脂シート３０の上面に圧接して矢印方向へ回転駆動される熱ローラとしての押圧ローラ５１と、実装基板母材４０の下面を支持して押圧ローラ５１との間で加圧力を発生するガイド部材としての支持ローラ５２とを備えている。押圧ローラ５１は、ヒータにより所要温度に加熱制御されると共に、駆動源により実装基板母材４０をラミネート方向へ送るように回転駆動される。そして、支持ローラ５２は、矢印方向へ連れ回り、或いは回転駆動される。この熱ローララミネート工程では、以下の条件を満たすことが求められる。
（ａ）押圧ローラ５１の加熱温度を樹脂シート３０の軟化（又は溶融）温度以上、且つ硬化温度未満に設定すること。
（ｂ）押圧ローラ５１によって樹脂シート３０を押圧ローラ５１にて加熱しながら加圧することにより軟化（又は溶融）させること。
（ｃ）軟化（又は溶融）した樹脂シート３０を押圧ローラ５１にて加熱しながら加圧することによって、樹脂シート本体３１をＳＡＷチップの谷間に充填、浸透させて、気密空間Ｓを保持しながらＳＡＷチップ１５を樹脂にて被覆すること。
複数のＳＡＷチップ１５上に跨って載置された樹脂シート３０を、ＳＡＷチップ１５外面から実装基板４０上面にかけて充填されることによりラミネートが行われる。なお、熱ローララミネート法では、ＳＡＷチップ１５と実装基板母材４０との間の気密空間Ｓが必要以上に拡張されないよう、樹脂シートの一端側から他端側へ向けて順次加圧してエアーを抜きながらラミネートすることができる。
【００２９】
ラミネート工程後のＳＡＷデバイスの断面図を図３（ｂ）に示す。本発明においては気密空間Ｓの外周に沿って枠体２０を設けたので、ラミネート工程時に樹脂シート３０がＳＡＷチップ１５の外面から実装基板母材４０の上面にかけて充填される際に、樹脂が気密空間Ｓに入り込むのを防止でき、また、枠体２０の厚みは実装基板母材４０上面から圧電基板１８底面までの間隙よりも小さいので、各ＳＡＷチップ１５を個片毎にエアーを抜きながら容易にラミネートすることができるのでボイドの発生を抑圧することができる。
【００３０】
ラミネート工程後、図４に示すようにプレス成形工程を行う。このプレス成形工程は、プレス成形装置６０によって実施される。前記プレス成形装置６０は、実装基板母材４０の底面を支持する金属型６１と、金属型６１上に支持された実装基板母材４０の外径方向に位置するスペーサ６２と、実装基板母材４０上にラミネートされた樹脂シート３０の上面外縁に沿って添設される押えフレーム６３と、該押えフレーム６３の上面を加圧する金属板（加圧部材）６４と、プレス機７０とを備えている。まず、ラミネート工程を終えた樹脂ラミネート済み実装基板母材（ラミネート済みユニットＵと称す）を、図４（ａ）のように金属型６１の上面に載置し、ラミネート済みユニットＵに過剰な圧力がかからぬように、ラミネート済みユニットＵの外径方向に離間してスペーサ６２を設ける。このスペーサ６２は、金属型６１の上面に固定する。そして、ラミネート済みユニットＵの樹脂シート３０上に、ＳＡＷチップ１５が実装されている領域よりも大きく開口した環状の押えフレーム６３を載せ、その上に金属板６４を載置する。ラミネート済みユニットＵを図４（ａ）のようにセットした後、プレス機７０を用いて図４（ｂ）に示すようにプレス成形を行う。このプレス機７０は、上型（加圧部材）７１と下型７２とからなり、上型７１と下型７２はそれぞれ樹脂の硬化温度に設定されている。下型７２上に金属型６１を載置すると共に、金属板６４の上面に上型７１を当接させてプレスを行う。プレスによって気密空間Ｓ内のエアーの膨張を強制的に抑えながら、樹脂を硬化させるのでエアーの膨張による気密空間Ｓの不要な拡大は発生しない。また、押えフレーム６３の下部に位置する樹脂を潰した状態でプレス成形することにより、実装基板母材４０上に搭載されたＳＡＷチップ群の外周縁に位置するＳＡＷチップの裾部（図４（ｂ）中のＢ部）に特に発生しやすいボイドが抑圧される。
【００３１】
プレス成形工程後、後硬化工程に入る。後硬化工程では、雰囲気温度を樹脂硬化温度に設定した恒温槽（後硬化装置）中にラミネート済みユニットＵを図５（ａ）のような状態で配置し加熱する。加熱時間は選択した樹脂シートの材質等の条件の違いによって適宜硬化条件を選択する必要がある。そして、樹脂が完全に硬化した後、図５（ａ）に示されているダイシング切り代に沿って幅Ｄのダイシングブレードにてダイシングし、図５（ｂ）のような個片のＳＡＷデバイス１が完成する。
【００３２】
以上説明したように、本発明においては、気密空間Ｓの外周に沿って枠体を設けたので、実装基板母材上に実装されたＳＡＷチップの箇所に関わらず、ラミネート工程時において樹脂が気密空間に入りこむのを防ぎ、また、ラミネートする際にエアーが抜きやすいように枠体の厚みを実装基板母材の上面とＳＡＷチップの下面との間隙より小さくしたので、ボイド発生を防止できるという効果を奏する。
【００３３】
なお、本実施例では、ラミネート工程は熱ローララミネート法を例に説明してきたが、本発明はこれのみに限るものではなく、順次エアーを抜きながらラミネートできる方法であれば熱ローラ以外の手段でもよく、図６に示すように所要温度に加熱されたブレード５５を用いて、ブレード５５のエッジ部を樹脂シート３０に圧接させながら矢印方向へ移動させることによって加熱と同時に加圧を行う方式も有効である。この場合には、ガイド部材としてステージ５３を使用する。なお、ラミネート工程を真空オーブンなどの減圧雰囲気中で行えば、更に効率よくエアーを抜くことができ、樹脂の密着性を高め、且つ適切な気密空間Ｓを形成することができる。また、ラミネート工程を窒素等の不活性ガス雰囲気中にて行えば、ＳＡＷデバイスの経年変化を防止し、特性を経時的に向上することができる。
【００３４】
次に、本発明に係る第二の実施例について説明する。図７は第二の実施例に係るＳＡＷデバイスのＳＡＷチップ１５を実装基板母材４０にフリップチップ実装し、樹脂をラミネート、プレス成形、後硬化した後の断面図である。本実施例の特徴は、第一の実施例で説明したＳＡＷチップ１５と実装基板母材４０との間の気密空間Ｓの外周に設けた枠体２０上に、積層するように第二の枠体２１を形成したことである。ここで、前記第二の枠体２１は以下の全ての条件を満たすように設置する。
（ａ）第一の枠体２０と第二の枠体２１の高さの和をＳＡＷチップ１５の上面の高さよりも低く設定すること。
（ｂ）第二の枠体２１の各辺の幅はダイシング切り代Ｄの幅よりも大きくすること。
（ｃ）第二の枠体２１はダイシング切り代Ｄを覆うように実装基板母材４０上面に設けること。
（ｄ）第二の枠体２１の各辺の幅は第一の枠体２０の各辺の幅よりも小さくすること。
このように、第一の枠体上に第二の枠体を設けることにより、第一の実施例と比較して、ラミネート工程時にボイドが発生してもダイシング切り代に到達しにくくなり、また、樹脂も気密空間Ｓに浸入しにくくなるので、より確実に気密空間を保持した高品質なＳＡＷデバイスを提供できる。
【００３５】
【発明の効果】
以上、説明したように本発明によれば、実装基板母材上にＳＡＷチップをフリップチップ実装して、樹脂をラミネートしたＳＡＷデバイス及びその製造方法において、気密空間の外周に沿って枠体を設けたので、実装基板母材上に実装されたＳＡＷチップの箇所に関わらず、ラミネート工程時におけるボイド発生を防止でき、また、気密空間内に樹脂が入り込むのを防止できるので、確実に気密空間を形成することができ、高品質なＳＡＷデバイスを提供することができる。
【図面の簡単な説明】
【図１】本発明の第一の実施例に係るＳＡＷデバイスの実装基板母材上にＳＡＷチップをフリップチップ実装する工程を示す図であり、（ａ）は平面図、（ｂ）は断面図である。
【図２】本発明の第一の実施例に係るＳＡＷデバイスのＳＡＷチップ上に樹脂シートを載置した状態を示す図である。
【図３】本発明の第一の実施例に係るＳＡＷデバイスの樹脂シートをＳＡＷチップ上にラミネートする工程を示す図であり、（ａ）はラミネート工程時の状態、（ｂ）はラミネート後の状態を示す。
【図４】本発明の第一の実施例に係るＳＡＷデバイスのプレス成形する工程を示す図であり、（ａ）はプレス装置にＳＡＷデバイスを設置した状態、（ｂ）はプレスした時の状態を示す。
【図５】本発明の第一の実施例に係るＳＡＷデバイスの（ａ）は後硬化工程の状態、（ｂ）はダイシング後の状態を示す。
【図６】本発明に係るブレードを用いたラミネート工程を示す。
【図７】本発明の第二の実施例に係るＳＡＷデバイスの樹脂封止後の断面図を示す。
【図８】従来のＳＡＷデバイスの実装基板母材上にＳＡＷチップをフリップチップ実装する工程を示す断面図である。
【図９】従来のＳＡＷデバイスのＳＡＷチップ上に樹脂シートを載置した状態を示す図である。
【図１０】従来のＳＡＷデバイスの樹脂シートをＳＡＷチップ上にラミネートする工程を示す図であり、（ａ）はラミネート工程時の状態、（ｂ）はラミネート後の状態を示す。
【図１１】従来のＳＡＷデバイスの後硬化工程後の状態を示す。
【図１２】従来のＳＡＷデバイスの完成品の状態を示す。
【図１３】従来のＳＡＷデバイスの欠陥品の状態を示す。
【図１４】第一の先行技術であるＳＡＷデバイスの断面図を示す。
【図１５】第二の先行技術であるＳＡＷデバイスの断面図を示す。
【符号の説明】
１：ＳＡＷデバイス、２：実装基板、３：絶縁基板、４：外部電極、５：配線パターン、６：内部導体、１０：導体バンプ、１５：ＳＡＷチップ、１６：接続パッド、１７：ＩＤＴ、１８：圧電基板、２０：枠体（第一の枠体）、２１、第二の枠体、３０：樹脂シート、３１：樹脂シート本体、３２：保護フィルム、４０：実装基板母材、５１：押圧ローラ、５２：支持ローラ、５５：ブレード、６０：プレス成形装置、６１：金属型、６２：スペーサ、６３：押えフレーム、６４：金属板（加圧部材）、７０：プレス機、７１：上型、７２：下型、[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface acoustic wave device, and more particularly to a surface acoustic wave device with a reduced package size and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, Surface Acoustic Wave (SAW) devices have been widely used in the field of mobile communication and have excellent characteristics in terms of high performance, small size, mass productivity, and the like. Have been. Further, with the generalization of small-sized packaging called CSP (Chip Size Package) in semiconductor components, from the viewpoint of facilitating miniaturization of filters in SAW devices and improving productivity by a batch-type manufacturing method. , A production method using CSP technology has been introduced.
[0003]
In the production method using the CSP technology described above, the inventor of the present invention proposed a resin encapsulation process of a SAW device including three processes of a lamination process, a press molding process, and a post-curing process in Japanese Patent Application No. 2002-293110. I have. Hereinafter, the resin sealing step will be described in detail with reference to FIGS. FIG. 8 is a cross-sectional view showing a step of flip-chip mounting the SAW chip 115 on the mounting substrate preform 140. The mounting substrate preform 140 has an external electrode 104 on the bottom of the insulating substrate 103 and a wiring pattern 105 on the top, and an internal conductor 106 for conducting the external electrode 104 and the wiring pattern 105 inside. The SAW chip 115 is a piezoelectric substrate. An IDT 117 for exciting the SAW and a connection pad 116 electrically connected to the IDT 117 are provided on the main surface of 118. Then, flip-chip mounting is performed by connecting the connection pads 116 of the SAW chip 115 on the wiring patterns 105 of the mounting substrate base material 140 using the conductive bumps 110.
[0004]
Next, as shown in FIG. 9, the resin sheet 130 is placed so as to straddle the upper surface of the piezoelectric substrate 118 of the plurality of SAW chips 115 mounted on the mounting substrate preform 140 of FIG. The resin sheet 130 has a protective film 132 having releasability attached to one surface of the resin sheet main body 131 in a releasable manner.
[0005]
Next, FIG. 10 is a cross-sectional view showing a heat roller laminating step of laminating the resin sheet 130 placed on each SAW chip 115 to the SAW chip 115 by the laminating device 150. The laminating apparatus 150 for performing the heat roller laminating step includes a moving unit that moves the mounting substrate preform 140 on which the SAW chip 115 is mounted at a predetermined laminating speed in a direction indicated by an arrow, and a resin sheet 130 on the SAW chip 115. A pressing roller 151 as a heat roller that is pressed against the upper surface of the substrate and is driven to rotate in the direction of the arrow, and a guide member that supports the lower surface of the mounting substrate 140 and generates a pressing force between the pressing roller 151 and the supporting member. And a roller 152. The pressing roller 151 is controlled to be heated to a required temperature by a heater, and is rotationally driven by a driving source so as to feed the mounting substrate preform 140 in the laminating direction. Then, the support roller 152 is rotated or driven in the direction of the arrow. In this heat roller laminating step, the following conditions are required to be satisfied.
(A) The heating temperature of the pressing roller 151 is set to be equal to or higher than the softening (or melting) temperature of the resin sheet 130 and lower than the curing temperature.
(B) The resin sheet 130 is softened (or melted) by being pressed by the pressing roller 151 while being heated by the pressing roller 151.
(C) By pressing the softened (or melted) resin sheet 130 while heating it with the pressing roller 151, the resin sheet main body 131 is filled and infiltrated into the valleys of the SAW chip, and the SAW is held while maintaining the airtight space S. Covering the chip 115 with resin.
The resin sheet 130 placed over the plurality of SAW chips 115 is filled from the outer surface of the SAW chip 115 to the upper surface of the mounting substrate preform 140 by the heat roller laminating step shown in FIG. And then laminate. In the heat roller laminating method, pressure is sequentially applied from one end to the other end of the resin sheet 130 so that the hermetic space S between the SAW chip 115 and the mounting substrate base material 140 is not expanded more than necessary. There is an advantage that lamination can be performed while removing air.
[0006]
Since the curing of the resin sheet 130 is not completed only by the laminating step, press molding is performed by heating the SAW chip having the outer surface laminated with the resin while pressing the resin, thereby suppressing the expansion of the gas in the hermetic space S. The process is performed, and further, a post-curing process is performed in which the mounting substrate base material is placed in a constant temperature bath in which the ambient temperature is set to the resin curing temperature and heated in order to completely cure the resin. FIG. 11 shows a state in which the above steps are completed. Then, the protective film 132 is peeled off, and the mounting substrate base material 140 is diced with a dicing blade along the dicing cut shown in FIG. 11, whereby the individual SAW device 100 as shown in FIG. 12 is completed.
[0007]
[Problems to be solved by the invention]
However, in the resin sealing step of the SAW device including the three steps of the laminating step, the press forming step, and the post-curing step as described above, air expansion (void) occurs in the laminating step, and the resin enters the airtight space S. Intrusion is a problem. This problem arises when the thickness of the resin sheet is set to be optimal for the SAW chip at the center of the mounting substrate base material. Significant voids are generated so as to reach the dicing allowance as shown in the SAW device 101, and conversely, the thickness of the resin sheet is reduced by the SAW chip arranged on the outermost peripheral portion of the mounting substrate base material. If it is set to be optimal, resin intrusion into the hermetic space S occurs in the SAW chip at the center of the mounting substrate base material. That is, there is a problem in that the intrusion state of the sealing resin varies between the central portion and the outermost peripheral portion of the mounting substrate base material.
[0008]
Therefore, in order to solve the above problem, application of a cavity type mounting substrate disclosed in Japanese Patent Application Laid-Open Nos. 11-214595 and 2000-261177 (hereinafter, these are referred to as Prior Art 1) has been proposed. investigated. FIG. 14 is a cross-sectional view of a SAW device using a cavity-type mounting substrate disclosed in Prior Art 1. A SAW chip 201 provided with an IDT 203 and a connection pad 204 electrically connected to the IDT 203 on a main surface of a piezoelectric substrate 202, a base 205a made of glass ceramic or alumina, and a member similar to the base 205a. It is composed of an annular laminated member 205b on which the outer peripheral portion is placed, and an annular frame 205c which forms a space wider than the laminated member 205b with a member similar to the base 205a, and a mounting pad 207 is provided on the upper surface of the base 205a. A mounting substrate 205 is provided, and connection pads 204 provided on the SAW chip 201 and mounting pads 207 provided on a substrate 205a of the mounting substrate 205 are conductively fixed via metal bumps 210, and the upper surface of the piezoelectric substrate 202 and The structure is such that the side surface is completely covered with the sealing resin 211.
[0009]
In the cavity-type mounting substrate described in the prior art 1, the cavity is filled with molten and liquefied resin and cured to form a sealing resin. Consider the case of adoption. As is apparent from FIG. 14, since the frame 205c disposed on the outer peripheral portion of the SAW chip 201 is higher than the upper surface of the SAW chip 201, when the resin 211 is laminated, there is no escape area for air and voids are generated. It has the disadvantage of being easy to do. As described in the related art, it is necessary to perform lamination while bleeding excess air in order to prevent voids from being generated in the laminating process. Laminating while removing air becomes difficult.
[0010]
Next, application of a laminating process to a minute air gap structure disclosed in Japanese Patent Application Laid-Open No. 10-22763 (hereinafter referred to as Prior Art 2) was studied. FIG. 15 is a longitudinal sectional view of a SAW device having a small air gap structure described in Prior Art 2. The SAW chip 301 in which the IDT 303 and the connection pad 304 electrically connected to the IDT 303 are arranged on the main surface of the piezoelectric substrate 302, the mounting pad 306 on the surface, and the insulating layer 307 in which a hole is provided in the portion of the mounting pad 306. A mounting board 305 is formed. The connection pads 304 provided on the SAW chip 301 and the mounting pads 306 provided on the mounting board 305 are flip-chip mounted with metal bumps 310 and then sealed with a sealant 311. This is a structure in which a stop air gap 320 is provided. The feature of the prior art 2 is that by providing an insulating layer 307 between the mounting substrate 305 and the SAW chip 301, the gap between the SAW chip 301 and the mounting substrate 305 can be reduced to zero as much as possible, and That is, it is prevented from flowing into the gap 320.
[0011]
In the prior art 2, an effect can be expected in which the sealing resin is less likely to enter the hermetic space by setting the hermetic space between the SAW chip and the mounting substrate to a minute gap. However, the structure of the SAW device described in Prior Art 2 requires a process of forming a hole in the mounting pad 306 after forming the insulating layer 307 on the mounting substrate 305. As a result, the area of the mounting pad 306 becomes very small, so that precise alignment of the mounting pad 306 with the hole requires a high-precision and strict operation, which is complicated. Further, since the holes provided on the insulating layer 307 are extremely small, there is a problem in manufacturing that a complicated operation is required when forming the metal bumps 310 on the mounting substrate 305.
[0012]
The present invention has been made in order to solve the above problems, and in a SAW device in which a SAW chip is flip-chip mounted on a mounting substrate base material and the surface is sealed with resin, an airtight space is easily formed, and Another object of the present invention is to provide a SAW device that prevents voids and resin from entering an airtight space when laminating a resin, and a method for manufacturing the same.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a SAW device according to the present invention and a method of manufacturing the SAW device according to the present invention include a surface acoustic wave chip, a mounting board having the surface acoustic wave chip flip-chip mounted on an upper surface thereof, A surface acoustic wave chip including an sealing resin that covers an outer surface of the surface acoustic wave chip and an upper surface of the mounting substrate while forming an airtight space between the IDT formed on the surface acoustic wave chip and the mounting substrate. A frame is formed on the upper surface of the mounting board so as to overlap a peripheral portion of the surface acoustic wave chip, and the frame has a thickness smaller than a gap between the surface acoustic wave chip and the mounting board. It is a surface acoustic wave device characterized by having.
[0014]
The invention according to claim 2 is one in which a second frame is laminated on the upper surface of the frame (first frame), and the second frame and the first frame are combined. A surface acoustic wave device characterized in that the thickness is smaller than the upper surface of the surface acoustic wave chip.
[0015]
According to a third aspect of the present invention, there is provided a frame forming step of forming a frame so as to cover a dicing cut along a dicing cut of a mounting board base material in which a plurality of mounting boards are connected in a sheet shape; A step of flip-chip mounting the surface acoustic wave chip on the mounting substrate base material using conductive bumps, a step of mounting a resin sheet on an upper surface of the surface acoustic wave chip mounted on the mounting substrate base material, and one end of the mounting substrate A laminating step of covering the outer surface of the surface acoustic wave chip with a resin by applying pressure while softening or melting the resin sheet toward the other end, and a press molding step of heating and curing the laminated resin while applying pressure. And a cutting step of cutting the surface acoustic wave chip into individual pieces along the dicing cutting margin. That.
[0016]
According to a fourth aspect of the present invention, in the frame forming step, the frame overlaps with a peripheral portion of the surface acoustic wave chip, and is larger than a gap between the flip-chip mounted surface acoustic wave chip and the mounting substrate base material. 4. The method according to claim 3, wherein the surface acoustic wave device is formed to have a small thickness.
[0017]
The invention according to claim 5 is that, in the frame forming step, a second frame is laminated on an upper surface of the frame (first frame), and the width of each side of the second frame is the first frame. 4. The surface acoustic wave chip according to claim 3, wherein the first frame and the second frame are formed to be smaller than the first frame and the combined thickness of the first frame and the second frame is smaller than the upper surface of the surface acoustic wave chip. And a method for manufacturing a surface acoustic wave device according to (4).
[0018]
In the invention according to claim 6, the thickness tr of the resin sheet in the laminating step is:
L / {(X + Gx) (Y + Gy)} ≦ tr
However, L = (X + Gx) (Y + Gy) (H + T + A) -XYT-XYA- {XVyA + YVxA + (4VxVyA) / 3}
(L: volume of the resin sheet necessary to seal the outer surface of one surface acoustic wave chip, X: length of one side of the surface acoustic wave chip, Y: length of the other side of the surface acoustic wave chip, Gx: Vx: distance between dicing cuts extending in the Y direction to the nearest surface of the surface acoustic wave chip, Gy: distance between surface acoustic wave chips adjacent in the Y direction, Vy: the distance from the dicing allowance extending in the X direction to the nearest surface of the surface acoustic wave chip, H: the resin located on the surface of the surface acoustic wave chip after the outer surface of one surface acoustic wave chip has been completely covered with the resin sheet. The surface acoustic wave device according to any one of claims 3 to 5, wherein T is the thickness of the piezoelectric substrate, and A is the distance from the top surface of the mounting substrate base material to the bottom surface of the piezoelectric substrate. Is the way.
[0019]
8. The mounting board base material according to claim 7, wherein the laminating step is performed between a pressing roller heated to a predetermined temperature, which rotates while being pressed against the resin sheet, and a guide member attached to a lower surface of the mounting board base material. And a heat roller laminating step of pressing the surface acoustic wave chip, wherein the heat roller laminating step sets the heating temperature of the pressing roller to be equal to or higher than the softening temperature or melting temperature of the resin sheet, and lower than the curing temperature, and is set by the pressing roller. The upper surface of the resin sheet is softened or melted by applying pressure while being heated, and the surface acoustic wave chip is coated with resin while securing an airtight space by applying pressure while heating the softened or melted resin sheet with a pressing roller. A method of manufacturing a surface acoustic wave filter according to any one of claims 3 to 6, wherein
[0020]
The laminating step may include a step of heating the resin sheet at a predetermined temperature and moving in one direction while being pressed against the upper surface of the resin sheet at a tip thereof, and a guide member attached to the lower surface of the mounting substrate base material. A blade laminating step of pressing the mounting substrate base material and the surface acoustic wave chip between the blade laminating step, wherein the heating temperature of the blade is set to a temperature equal to or higher than the softening temperature or melting temperature of the resin sheet, and lower than the curing temperature, The upper surface of the resin sheet is heated and pressurized while being softened or melted, and the softened or melted resin sheet is heated and pressurized with a blade to cover the surface acoustic wave chip with resin while securing an airtight space. A method of manufacturing a surface acoustic wave filter according to any one of claims 3 to 6, wherein
[0021]
The invention according to claim 9 is the method for manufacturing a surface acoustic wave device according to any one of claims 3 to 8, wherein the laminating step is performed in a reduced-pressure atmosphere.
[0022]
The invention according to claim 10 is the method for manufacturing a surface acoustic wave device according to any one of claims 3 to 8, wherein the laminating step is performed in an inert gas atmosphere.
[0023]
According to an eleventh aspect of the present invention, in the press forming step, a first plate jig in contact with a lower surface side of the mounting substrate base material and a second plate jig in contact with a resin sheet on the upper surface of the mounting substrate base material. Heat-curing while applying pressure while sandwiching the mounting board base material therebetween, and pressing the resin sheet peripheral portion against the mounting board base material upper surface on the lower surface of the second plate jig. 11. The method for manufacturing a surface acoustic wave device according to claim 3, wherein the holding frame is formed.
[0024]
The invention according to claim 12, wherein in the press forming step, a spacer member is provided on the upper surface of the first plate jig to limit a gap between the lower surface of the second plate jig and the lower surface of the second plate jig. 13. The method of manufacturing a surface acoustic wave filter according to claim 12, wherein
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. 1 to 5 show a method of manufacturing a SAW device according to a first embodiment of the present invention. First, FIGS. 1A and 1B are a plan view and a sectional view showing a step of flip-chip mounting a SAW chip 15 on a plurality of mounting substrate base materials 2 having a structure in which the mounting substrates 2 are connected in a sheet shape. is there. The mounting substrate 2 has an external electrode 4 for surface mounting on the bottom of the insulating substrate 3 and a wiring pattern 5 for conducting with the SAW chip 15 on the upper part. The conductor 6 is provided. The SAW chip 15 has an IDT 17 for exciting the SAW on the main surface of the piezoelectric substrate 18 and connection pads 16 electrically connected to the IDT 17. Then, flip-chip mounting is performed by connecting the wiring patterns 5 on the mounting substrate 2 and the connection pads 16 on the SAW chip 15 using the conductive bumps 10. A feature of the present invention is that a frame 20 is provided around each individual SAW chip of the mounting substrate 40 as shown in FIG. Here, the frame body 20 is installed so as to satisfy all the following conditions.
(A) The frame body 20 is provided on the outer periphery of the space S between the SAW chip 15 and the mounting substrate base material 40 and has a thickness smaller than a gap from the upper surface of the mounting substrate base material 40 to the bottom surface of the piezoelectric substrate 18. .
(B) The width of each side of the frame body 20 is larger than the dicing allowance D.
(C) The frame body 20 is provided on the mounting substrate 40 so as to cover the dicing allowance D.
(D) At least a part of the frame 20 is sandwiched between the piezoelectric substrate 18 and the mounting substrate 40. That is, the frame body 20 is set so as to overlap the periphery of the SAW chip 15.
[0026]
Next, as shown in FIG. 2, the resin sheet 30 is placed so as to straddle the upper surfaces of the plurality of SAW chips 15 mounted on the mounting substrate 40 of FIG. The resin sheet 30 has a releasable protective film 32 affixed to one surface of the resin sheet main body 31 in a releasable manner.
[0027]
Here, assuming that the thickness of the resin sheet main body 31 is tr, tr is set under the following conditions.
L / {(X + Gx) (Y + Gy)} ≦ tr
However, L = (X + Gx) (Y + Gy) (H + T + A) -XYT-XYA- {XVyA + YVxA + (4VxVyA) / 3}
(L: volume of resin sheet required to seal the outer surface of one SAW chip, X: length of one side of SAW chip, Y: length of other side of SAW chip, Gx: adjacent to each other in X direction The distance between the SAW chips, Vx: the distance from the dicing cut extending in the Y direction to the nearest side of the SAW chip, Gy: the distance between adjacent SAW chips in the Y direction, Vy: the distance from the dicing cut extending in the X direction. Distance to SAW chip side surface, H: Thickness of resin located on SAW chip upper surface after completion of covering one SAW chip outer surface with resin sheet, T: Piezoelectric substrate thickness, A: Mounting substrate base material upper surface From the substrate to the bottom of the piezoelectric substrate)
As described above, by setting the thickness of the resin sheet main body 31, when the resin is later laminated on the SAW device, the thickness of the resin becomes insufficient and a hole is opened in the hermetic space S to improve the dustproof and moistureproof properties of the SAW device. There is no danger of lowering.
[0028]
After placing the resin sheet 30 on the SAW chip 15, a laminating step is performed as shown in FIG. In this embodiment, an example in which a heat roller laminating method is used as in the related art will be described. The laminating apparatus 50 for performing the heat roller laminating step includes a moving unit that moves the mounting substrate preform 40 on which the SAW chip 15 is mounted in a direction indicated by an arrow at a predetermined laminating speed, and a resin sheet 30 on the SAW chip 15. A pressing roller 51 as a heat roller that is pressed against the upper surface of the substrate and is driven to rotate in the direction of the arrow, and a guide member that supports the lower surface of the mounting substrate 40 and generates a pressing force between the pressing roller 51 and the supporting member. And a roller 52. The pressing roller 51 is controlled to be heated to a required temperature by a heater, and is rotationally driven by a driving source so as to feed the mounting substrate preform 40 in the laminating direction. Then, the support roller 52 is rotated or driven in the direction of the arrow. In this heat roller laminating step, the following conditions are required to be satisfied.
(A) The heating temperature of the pressing roller 51 is set to be equal to or higher than the softening (or melting) temperature of the resin sheet 30 and lower than the curing temperature.
(B) Softening (or melting) the resin sheet 30 by applying pressure while heating the resin sheet 30 with the pressing roller 51.
(C) By pressing the softened (or melted) resin sheet 30 while heating it with the pressing roller 51, the resin sheet main body 31 is filled and permeated into the valleys of the SAW chips, and the SAW is held while maintaining the airtight space S. Covering the chip 15 with resin.
Lamination is performed by filling the resin sheet 30 placed on the plurality of SAW chips 15 from the outer surface of the SAW chip 15 to the upper surface of the mounting substrate 40. In the heat roller lamination method, air is applied by sequentially applying pressure from one end to the other end of the resin sheet so that the hermetic space S between the SAW chip 15 and the mounting substrate 40 is not unnecessarily expanded. Lamination can be performed while pulling out.
[0029]
FIG. 3B is a cross-sectional view of the SAW device after the laminating step. In the present invention, since the frame body 20 is provided along the outer periphery of the hermetic space S, when the resin sheet 30 is filled from the outer surface of the SAW chip 15 to the upper surface of the mounting substrate base material 40 during the laminating step, the resin is hermetically sealed. It is possible to prevent entry into the space S, and since the thickness of the frame body 20 is smaller than the gap from the upper surface of the mounting substrate base material 40 to the bottom surface of the piezoelectric substrate 18, each SAW chip 15 can be easily removed while removing air for each piece. Since it can be laminated, the generation of voids can be suppressed.
[0030]
After the laminating step, a press forming step is performed as shown in FIG. This press forming step is performed by the press forming device 60. The press forming apparatus 60 includes a metal mold 61 that supports the bottom surface of the mounting substrate preform 40, a spacer 62 that is positioned on the mounting die preform 40 supported on the metal mold 61 in an outer radial direction, and a mounting substrate preform. A pressing frame 63 is provided along the outer edge of the upper surface of the resin sheet 30 laminated on the metal sheet 40, a metal plate (pressing member) 64 for pressing the upper surface of the pressing frame 63, and a press machine 70. I have. First, a resin-laminated mounting substrate base material (referred to as a laminated unit U) after the laminating step is placed on the upper surface of the metal mold 61 as shown in FIG. The spacers 62 are provided apart from each other in the outer diameter direction of the laminated unit U so as not to cover. This spacer 62 is fixed on the upper surface of the metal mold 61. Then, on the resin sheet 30 of the laminated unit U, the annular holding frame 63 having an opening larger than the area where the SAW chip 15 is mounted is placed, and the metal plate 64 is placed thereon. After setting the laminated unit U as shown in FIG. 4A, press molding is performed using a press machine 70 as shown in FIG. The press 70 includes an upper die (pressing member) 71 and a lower die 72, and the upper die 71 and the lower die 72 are each set to a resin curing temperature. The metal mold 61 is placed on the lower mold 72, and the upper mold 71 is pressed against the upper surface of the metal plate 64 to perform pressing. Since the resin is cured while the expansion of the air in the hermetic space S is forcibly suppressed by the press, unnecessary expansion of the hermetic space S due to the expansion of the air does not occur. Also, by pressing the resin located at the lower portion of the holding frame 63 in a crushed state, the skirt portion of the SAW chip located at the outer peripheral edge of the group of SAW chips mounted on the mounting substrate base material 40 (FIG. Voids that are particularly likely to occur in part B) in b) are suppressed.
[0031]
After the press molding process, a post-curing process is started. In the post-curing step, the laminated unit U is placed in a thermostat (post-curing device) in which the ambient temperature is set to the resin curing temperature in a state as shown in FIG. As for the heating time, it is necessary to appropriately select the curing conditions depending on the selected conditions such as the material of the resin sheet. Then, after the resin is completely cured, dicing is performed with a dicing blade having a width D along a dicing cut margin shown in FIG. 5A, and the individual SAW device 1 as shown in FIG. Is completed.
[0032]
As described above, in the present invention, since the frame is provided along the outer periphery of the hermetic space S, the resin is airtight during the laminating step regardless of the position of the SAW chip mounted on the mounting substrate base material. The thickness of the frame is made smaller than the gap between the upper surface of the mounting substrate base material and the lower surface of the SAW chip so that it can be prevented from entering the space and air can be easily removed when laminating, so that voids can be prevented. To play.
[0033]
In the present embodiment, the laminating step has been described by taking the heat roller laminating method as an example.However, the present invention is not limited to this. It is also effective to use a blade 55 heated to a required temperature as shown in FIG. 6 and to move the edge portion of the blade 55 in the direction of the arrow while pressing the edge portion of the blade 55 against the resin sheet 30 to simultaneously perform heating and pressing. It is. In this case, the stage 53 is used as a guide member. If the laminating step is performed in a reduced-pressure atmosphere such as a vacuum oven, the air can be more efficiently evacuated, the adhesiveness of the resin can be increased, and an appropriate hermetic space S can be formed. Further, if the laminating step is performed in an atmosphere of an inert gas such as nitrogen, the aging of the SAW device can be prevented, and the characteristics can be improved over time.
[0034]
Next, a second embodiment according to the present invention will be described. FIG. 7 is a cross-sectional view after the SAW chip 15 of the SAW device according to the second embodiment is flip-chip mounted on the mounting substrate 40, and the resin is laminated, pressed, and post-cured. The feature of this embodiment is that the second frame is laminated on the frame 20 provided on the outer periphery of the hermetic space S between the SAW chip 15 and the mounting board base material 40 described in the first embodiment. That is, the body 21 is formed. Here, the second frame 21 is installed so as to satisfy all the following conditions.
(A) The sum of the heights of the first frame 20 and the second frame 21 is set lower than the height of the upper surface of the SAW chip 15.
(B) The width of each side of the second frame 21 should be larger than the width of the dicing allowance D.
(C) The second frame 21 is provided on the upper surface of the mounting board base material 40 so as to cover the dicing allowance D.
(D) The width of each side of the second frame 21 is smaller than the width of each side of the first frame 20.
Thus, by providing the second frame on the first frame, compared to the first embodiment, even if voids occur during the laminating step, it is difficult to reach the dicing allowance, In addition, since the resin does not easily enter the airtight space S, a high-quality SAW device that more reliably retains the airtight space can be provided.
[0035]
【The invention's effect】
As described above, according to the present invention, in a SAW device in which a SAW chip is flip-chip mounted on a mounting substrate base material and a resin is laminated, and a method of manufacturing the SAW device, a frame is provided along the outer periphery of an airtight space. Therefore, irrespective of the location of the SAW chip mounted on the mounting substrate base material, it is possible to prevent the occurrence of voids during the laminating process and prevent the resin from entering the hermetically sealed space. Thus, a high-quality SAW device can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a step of flip-chip mounting a SAW chip on a mounting substrate base material of a SAW device according to a first embodiment of the present invention, (a) is a plan view, and (b) is a cross-sectional view. It is.
FIG. 2 is a diagram showing a state in which a resin sheet is mounted on a SAW chip of the SAW device according to the first embodiment of the present invention.
FIGS. 3A and 3B are diagrams illustrating a step of laminating a resin sheet of a SAW device on a SAW chip according to the first embodiment of the present invention, wherein FIG. Indicates the status.
FIGS. 4A and 4B are views showing a step of press-molding a SAW device according to the first embodiment of the present invention, wherein FIG. 4A shows a state in which the SAW device is installed in a press device, and FIG. Is shown.
FIG. 5A shows the state of the post-curing step of the SAW device according to the first embodiment of the present invention, and FIG. 5B shows the state after dicing.
FIG. 6 shows a laminating step using the blade according to the present invention.
FIG. 7 is a sectional view of a SAW device according to a second embodiment of the present invention after resin sealing.
FIG. 8 is a cross-sectional view showing a process of flip-chip mounting a SAW chip on a mounting substrate base material of a conventional SAW device.
FIG. 9 is a diagram showing a state in which a resin sheet is mounted on a SAW chip of a conventional SAW device.
10A and 10B are diagrams illustrating a process of laminating a resin sheet of a conventional SAW device on a SAW chip, wherein FIG. 10A illustrates a state during a laminating process, and FIG. 10B illustrates a state after laminating.
FIG. 11 shows a state after a post-curing step of a conventional SAW device.
FIG. 12 shows a state of a finished product of a conventional SAW device.
FIG. 13 shows a state of a defective product of a conventional SAW device.
FIG. 14 shows a cross-sectional view of a first prior art SAW device.
FIG. 15 shows a cross-sectional view of a second prior art SAW device.
[Explanation of symbols]
1: SAW device, 2: mounting substrate, 3: insulating substrate, 4: external electrode, 5: wiring pattern, 6: internal conductor, 10: conductor bump, 15: SAW chip, 16: connection pad, 17: IDT, 18 : Piezoelectric substrate, 20: frame (first frame), 21, second frame, 30: resin sheet, 31: resin sheet body, 32: protective film, 40: mounting substrate base material, 51: pressing Roller, 52: support roller, 55: blade, 60: press forming device, 61: metal mold, 62: spacer, 63: holding frame, 64: metal plate (pressing member), 70: press machine, 71: upper mold , 72: lower mold,

Claims

A surface acoustic wave chip, a mounting substrate on which the surface acoustic wave chip is flip-chip mounted on an upper surface, and the surface acoustic wave while forming an airtight space between the IDT formed on the surface acoustic wave chip and the mounting substrate. A surface acoustic wave chip comprising a sealing resin covering an outer surface of the chip and an upper surface of the mounting substrate,
A frame is formed on the upper surface of the mounting substrate so as to overlap with a peripheral portion of the surface acoustic wave chip, and the frame has a thickness smaller than a gap between the surface acoustic wave chip and the mounting substrate. Characteristic surface acoustic wave device.

A second frame is laminated on the upper surface of the frame (first frame), and the combined thickness of the second frame and the first frame is equal to the thickness of the surface acoustic wave chip. A surface acoustic wave device characterized by being lower than an upper surface.

A frame forming step of forming a frame so as to cover the dicing cut along a dicing cut of a mounting board base material in which a plurality of mounting boards are connected in a sheet shape,
A step of flip-chip mounting the surface acoustic wave chip using a conductive bump on the mounting substrate base material,
A step of mounting a resin sheet on the upper surface of the surface acoustic wave chip mounted on the mounting substrate base material,
A laminating step of covering the outer surface of the surface acoustic wave chip with a resin by applying pressure while softening or melting the resin sheet from one end to the other end of the mounting board,
Press molding step of heating and curing the laminated resin while applying pressure,
Cutting the surface acoustic wave chip into individual pieces along the dicing cutting margin.

In the frame forming step, the frame is formed so as to overlap with a peripheral portion of the surface acoustic wave chip and to have a thickness smaller than a gap between the surface acoustic wave chip mounted by flip chip mounting and a mounting substrate base material. 4. The method of manufacturing a surface acoustic wave device according to claim 3, wherein

In the frame forming step, a second frame is laminated on the upper surface of the frame (first frame), and the width of each side of the second frame is smaller than that of the first frame. 5. The surface acoustic wave according to claim 3, wherein the combined thickness of the first frame and the second frame is lower than the upper surface of the surface acoustic wave chip. 6. Device manufacturing method.

The thickness tr of the resin sheet during the laminating step is:
L / {(X + Gx) (Y + Gy)} ≦ tr
However, L = (X + Gx) (Y + Gy) (H + T + A) -XYT-XYA- {XVyA + YVxA + (4VxVyA) / 3}
(L: volume of the resin sheet necessary to seal the outer surface of one surface acoustic wave chip, X: length of one side of the surface acoustic wave chip, Y: length of the other side of the surface acoustic wave chip, Gx: Vx: distance between dicing cuts extending in the Y direction to the nearest surface of the surface acoustic wave chip, Gy: distance between surface acoustic wave chips adjacent in the Y direction, Vy: the distance from the dicing allowance extending in the X direction to the nearest surface of the surface acoustic wave chip, H: the resin located on the surface of the surface acoustic wave chip after the outer surface of one surface acoustic wave chip has been completely covered with the resin sheet. The surface acoustic wave device according to any one of claims 3 to 5, wherein T is the thickness of the piezoelectric substrate, and A is the distance from the top surface of the mounting substrate base material to the bottom surface of the piezoelectric substrate. Method.

The laminating step presses the mounting substrate base material and the surface acoustic wave chip between a pressing roller heated to a predetermined temperature that rotates while being pressed against the resin sheet and a guide member attached to a lower surface of the mounting substrate base material. The heat roller laminating step comprises setting the heating temperature of the pressing roller to a temperature equal to or higher than the softening temperature or melting temperature of the resin sheet, and lower than the curing temperature, and heating the upper surface of the resin sheet by the pressing roller. The surface acoustic wave chip is covered with a resin while securing an airtight space by applying pressure while heating or softening the softened or melted resin sheet with a pressing roller. 7. A method for manufacturing a surface acoustic wave filter according to any one of 3 to 6.

In the laminating step, the mounting board base material and the elasticity are moved between a blade heated to a predetermined temperature, which moves in one direction while being pressed against the upper surface of the resin sheet at one end, and a guide member attached to the lower surface of the mounting board base material. It consists of a blade laminating step of pressing the surface acoustic wave chip, the blade laminating step is set at a temperature higher than the softening temperature or melting temperature of the resin sheet and lower than the curing temperature of the resin sheet, and the upper surface of the resin sheet is heated by the blade. The surface acoustic wave chip is coated with a resin while securing an airtight space by applying pressure while heating the softened or molten resin sheet with a blade while applying pressure while softening or melting the resin sheet. 7. A method for manufacturing a surface acoustic wave filter according to any one of 3 to 6.

9. The method according to claim 3, wherein the laminating step is performed in a reduced pressure atmosphere.

9. The method according to claim 3, wherein the laminating step is performed in an inert gas atmosphere.

The press forming step includes, between a first plate jig contacting the lower surface side of the mounting substrate preform and a second plate jig contacting a resin sheet on the mounting substrate preform upper surface, mounting the mounting substrate preform. It is cured by heating while pressing while sandwiching it,
11. A holding frame for holding a peripheral portion of the resin sheet against an upper surface of the mounting substrate base material is formed on a lower surface of the second plate jig. Production method of a surface acoustic wave device.

The press forming step is characterized in that a spacer member is formed on an upper surface of the first plate jig to limit a gap between the lower surface of the second plate jig and the gap therebetween. A method for manufacturing a surface acoustic wave filter according to claim 11.