JP4296778B2 - Manufacturing method of surface acoustic wave device - Google Patents

Manufacturing method of surface acoustic wave device Download PDF

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JP4296778B2
JP4296778B2 JP2002365511A JP2002365511A JP4296778B2 JP 4296778 B2 JP4296778 B2 JP 4296778B2 JP 2002365511 A JP2002365511 A JP 2002365511A JP 2002365511 A JP2002365511 A JP 2002365511A JP 4296778 B2 JP4296778 B2 JP 4296778B2
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acoustic wave
surface acoustic
package
temperature
wave element
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JP2004200908A (en
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直弘 野竹
忠彦 高田
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Murata Manufacturing Co Ltd
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Murata Manufacturing 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

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  • Wire Bonding (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、弾性表面波装置に係わり、特にパッケージ内に弾性表面波素子を搭載した弾性表面波装置に関する。
【０００２】
【従来の技術】
近年、自動車電話機や携帯電話機といった移動体通信機器の小型化、軽量化、高周波化に伴い、これらの移動体通信機器に搭載されるフィルタとして、小型で軽量な弾性表面波装置（弾性表面波フィルタ）が多用されている。特に携帯電話機は特に小型で軽量であることが強く要求されるため、搭載される弾性表面波装置においても同様に小型で軽量であることが要求されている。
【０００３】
弾性表面波装置は、このような要求に対応するため、弾性表面波素子をパッケージに搭載する際、従来のワイヤボンディング法から、Ａｕ又はＡｕを主成分とする金属バンプを用いたフリップチップボンディング法へ移行しつつある。
【０００４】
弾性表面波素子をパッケージにフリップチップボンディング法で搭載する際、まず、弾性表面波素子の電極パッド上に、Ａｕ又はＡｕを主成分とする金属バンプをボールボンディング法によって形成する。次に、弾性表面波素子のくし型電極部などが形成された弾性表面波伝播面をパッケージのダイアタッチ面に対向させ、ボンディングツールによって弾性表面波素子の裏面に超音波と荷重とを同時に印加する。これによって、弾性表面波素子の各電極パッドとこれに対応するパッケージの各電極ランドとをＡｕ又はＡｕを主成分とする金属バンプで接合して、弾性表面波素子をパッケージに接続・固定する。
【０００５】
従来、ボンディングツールによって弾性表面波素子の裏面に、超音波と荷重とを同時に印加する際、Ａｕ又はＡｕを主成分とする金属バンプの再結晶温度よりも高い温度にパッケージを熱した状態でボンディングツールを用い、超音波・荷重・熱を同時に印加して接合を行なうと、金属バンプの固相拡散・組成変形が促進されて接合が良くなる。このため、Ａｕ又はＡｕを主成分とする金属バンプの再結晶温度である２００度よりも高い温度にパッケージを熱して、弾性表面波素子を搭載していた。
【０００６】
また、１つのパッケージに２つ以上の弾性表面波素子を搭載する場合も同様に、Ａｕ又はＡｕを主成分とする金属バンプの再結晶温度である２００度よりも高い温度にパッケージを熱した状態でボンディングツールを用い、搭載する全ての弾性表面波素子に対して同時に、超音波・荷重・熱を印加してパッケージとの接合を行なっていた。
【０００７】
【特許文献１】
特開平１１−１２２０７２号公報
【０００８】
【発明が解決しようとする課題】
しかしながら、高周波化に伴い、特に中心周波数が１ＧＨｚ以上と高い周波数特性を有する弾性表面波素子を、Ａｕ又はＡｕを主成分とする金属バンプの再結晶温度である２００度よりも高い温度にパッケージを熱した状態でボンディングツールを用い、超音波・荷重・熱を印加してパッケージに接合しようとすると、弾性表面波素子の電極指破壊が発生する。
【０００９】
これは、パッケージの直上に弾性表面波素子を位置させてから実装するまでの間に、２００度よりも高い温度に熱したパッケージの温度の影響を受けて、弾性表面波素子の圧電基板の温度が常温から加熱したパッケージの温度まで急速に上がるため、この急な温度勾配（単位時間あたりの温度変化）により、圧電基板の焦電性によって、くし型電極部の電極指間に電荷が発生、ショートし、電極指の焦電破壊が発生したためである。
【００１０】
ここで、焦電性とは、タンタル酸リチウム（ＬｉＴａＯ3）、ニオブ酸リチウム（ＬｉＮｂＯ3）などの圧電基板が有する、結晶を熱すると一方の端は正に他方の端は負に帯電し、温度が違うと基板の膨張の程度が違うので内部の自発分極に差が現れ、その影響で基板表面に電荷が発生するという性質のことをいう。
【００１１】
また、焦電破壊とは、急な温度勾配（時間あたりの温度変化）の影響で上述の圧電基板の焦電性により弾性表面波素子に電位が発生し、くし型電極部の電極指間の電荷が大きくなると間隔の狭い電極指間で放電し、その熱の影響で電極指が焦げて（溶けて）変形したり、非接触でなければいけないのに接触してしまったりすること、つまり、圧電基板の焦電性を原因とする電極破壊をいう。
【００１２】
圧電基板の焦電性によって発生する電荷は温度勾配に比例するので、基板温度が常温から高い温度まで急に上がるほど、その分、焦電破壊は起こりやすくなる。また、電極指のギャップが狭いほど、発生した電荷によるショートが起こりやすくなる。特に、高い周波数特性を有する弾性表面波素子においては、電極指ピッチが狭くなるので、電極指のギャップも狭くなる。特に中心周波数が１ＧＨｚ以上の弾性表面波素子の電極指のギャップの平均は、約１μｍ以下とかなり狭いため、焦電破壊が起こりやすい。ここで、図６に示すように、くし型電極部を構成するくし歯状電極において、電極指ピッチは一方のくし歯状電極の電極指から対向する、他方のくし歯状電極の電極指の端部までの間隔を、電極指のギャップは、一方のくし歯状電極の電極指と、その電極指に隣接する他方のくし歯状電極の電極指との間隔をいう。
【００１３】
本発明の弾性表面波の製造方法は、上述の問題を鑑みてなされたものであり、これらの問題を解決し、特に中心周波数が１ＧＨｚ以上の高い周波数帯に用いる弾性表面波素子を、焦電破壊を防止しつつ、パッケージに良好な密着強度で接合する弾性表面波装置の製造方法を提供することを目的としている。
【００１４】
【課題を解決するための手段】
上記目的を達成するため、本発明の第一の弾性表面波装置の製造方法は、圧電基板上に形成された少なくとも一つのくし型電極部を有する複数の弾性表面波素子を、Ａｕめっきされた電極ランドが形成されたパッケージに、Ａｕ若しくはＡｕ合金からなる金属バンプを用いて超音波と荷重を同時に印加するフリップチップボンディング法により搭載する弾性表面波装置の製造方法であって、前記複数の弾性表面波素子のうち少なくとも一つは、残余のものより、前記くし型電極部を構成する電極指のギャップの平均が小さく、該くし型電極部を構成する電極指のギャップの平均が小さい弾性表面波素子を前記金属バンプの再結晶温度よりも低い温度で前記パッケージに搭載した後、残余の弾性表面波素子を前記金属バンプの再結晶温度よりも高い温度で前記パッケージに搭載することを特徴とする。
【００１５】
これにより、まず、電極指のギャップの平均が小さいために焦電破壊が起こりやすい、相対的に高い周波数特性を有する弾性表面波素子を金属バンプの再結晶温度よりも低い温度で先に搭載してパッケージのアースと導通させる。このとき、パッケージの温度は金属バンプの再結晶温度よりも低いので、パッケージの直上に弾性表面波素子を位置させてから実装するまでの間での、弾性表面波素子の圧電基板の温度変化、つまり温度勾配（単位時間あたりの温度変化）が小さいので、焦電破壊は発生しない。次いで、残余の相対的に低い周波数特性を有する弾性表面波素子を搭載する際に、金属バンプの再結晶温度よりも高い温度までパッケージを加熱しても、相対的に高い周波数特性を有する弾性表面波素子はパッケージのアースと導通されているために圧電基板の焦電性によって発生した電荷はパッケージに移り、くし型電極部の電極指間では放電が発生せず、焦電破壊が起こらない。
【００１６】
電極指のギャップの平均が小さい、つまり、相対的に高い周波数特性を有する弾性表面波素子のパッケージとの接合強度は、焦電破壊が起こらない程度の低い温度で接合されるので弱いものとなる。しかし、続けて、残余の相対的に低い周波数特性を有する弾性表面波素子を搭載する際に、金属バンプの再結晶温度よりも高い温度までパッケージを熱するので、それと共に、相対的に高い周波数特性を有する弾性表面波素子の接合界面も温度が上がり、金属バンプの固相拡散が促進されるために接合が良くなる。
【００１７】
なお、電極指のギャップの平均とは、弾性表面波素子における、全てのくし型電極部を構成する一方のくし歯状電極の電極指と、その電極指に隣接する他方のくし歯状電極の電極指との間隔の平均のことを意味する。
【００１９】
これにより、電極指のギャップの平均が小さいために焦電破壊が起こりやすい、高い周波数特性を有する弾性表面波素子を金属バンプの再結晶温度よりも低い温度で搭載して、弾性表面波素子をパッケージのアースと導通させることで、後に金属バンプの再結晶温度よりも高い温度で熱処理しても、弾性表面波素子はパッケージのアースと導通されているので、圧電基板の焦電性によって発生した電荷はパッケージに移り、くし型電極部の電極指間に放電は発生せず、焦電破壊が起こらない。
【００２０】
弾性表面波素子の接合強度は、当初、金属バンプの再結晶温度よりも低い温度で接合されるので弱いものであるが、搭載後に、バンプの再結晶温度よりも高い温度で熱処理すると、パッケージと弾性表面波素子の接合界面の温度が上がり、金属バンプの固相拡散が促進されるために接合が良くなる。
【００２２】
また、金属バンプの再結晶温度が約２００度であることが好ましい。
【００２３】
また、前記弾性表面波素子の電極指のギャップの平均が約１μｍ以下であることが好ましい。
【００２４】
【発明の実施の形態】
以下、本発明の実施例を、図に基づいて説明する。
（実施の形態１）図１は本発明の第一の実施例における弾性表面波素子を実装する工程図、図２は本発明に用いる弾性表面波素子のくし型電極の平面図、図３は本発明におけるパッケージの加熱温度と焦電破壊発生率の関係を示す図、図４は本発明におけるパッケージに搭載された弾性表面波素子の金属バンプシェア強度を示す図である。
【００２５】
まず、図１（ａ）に示すように、複数層のアルミナセラミックシートを積層することで凹部形状に形成されてなるパッケージ４を用意する。パッケージ４のダイアタッチ面は図示しないが、該パッケージ４に搭載される弾性表面波素子２と金属バンプ３を介して電気的に接続される複数の電極ランド及び配線が形成されており、これらはＡｕめっきされている。複数の電極ランド及び配線がＡｕめっきされていることで、金属バンプ３にＡｕ又はＡｕを主成分とする合金を用いた場合、特に接合しやすい。また、パッケージ４の裏面から側面には外部端子４１が形成されている。なお、パッケージ４はセラミックではなく、樹脂で形成されていてもよい。
【００２６】
パッケージ４と共に、互いに異なる周波数特性を有する２つの弾性表面波素子２ａ、２ｂを用意する。弾性表面波素子は２ａ、相対的に高い周波数特性、つまり、弾性表面波素子は２ｂより高い周波数特性を有し、弾性表面波素子２ｂは相対的に低い周波数特性、つまり、弾性表面波素子は２ａより低い周波数特性を有する。より詳細には、相対的に高い周波数特性を有する弾性表面波素子は、中心周波数が１ＧＨｚであり、電極指のギャップの平均が約１μｍ、電極指ピッチが約２μｍである。相対的に低い周波数特性を有する弾性表面波素子は、中心周波数が８００ＭＨｚであり、電極指のギャップの平均が約１．５μｍ、電極指ピッチが２．５μｍである。
【００２７】
弾性表面波素子２ａ及び２ｂは、図２に示すように、圧電基板２１の一方主面にＡｌ又はＡｌを主成分とする合金により形成されている、くし型電極部２２、反射器２３、配線２４、電極パッド２５を有する。圧電基板２１としては、タンタル酸リチウム（ＬｉＴａＯ3）、ニオブ酸リチウム（ＬｉＮｂＯ3）などを用いる。また、電極パッド２５上には、Ａｕ又はＡｕを主成分とする金属バンプ３をボールボンディング法によって形成する。金属バンプ３として、Ａｕは電極の材料となるＡｌとの接合性が良く、安定で、腐食、酸化しないので、好適に用いられる。
【００２８】
次に、図１（ｂ）に示すように、相対的に高い周波数特性を有する弾性表面波素子２ａを用意し、この弾性表面波素子２ａをくし型電極部などが形成された弾性表面波伝播面をパッケージのダイアタッチ面に対向させると共に、パッケージ４をワーク（図示せず）で支持した状態で、ボンディングツール５によって弾性表面波素子２ａの裏面に超音波と荷重とを同時に印加することで、パッケージ４に搭載する。このとき、パッケージ４はＡｕ又はＡｕを主成分とする金属バンプ３の再結晶温度である約２００度よりも低い温度である１７０度に熱されている。これによって、弾性表面波素子２ａの複数の電極パッド２５とこれに対応するパッケージ４の各電極ランドとをＡｕ又はＡｕを主成分とする金属バンプ３を介して接合し、相対的に高い周波数特性を有する弾性表面波素子２ａをパッケージ４に接続・固定する共に、電気的に接続する。
【００２９】
図３に、パッケージに電極指のギャップの平均が約１μｍの弾性表面波素子を搭載する際の、パッケージの加熱温度と弾性表面波素子の焦電破壊発生率の関係が示されている。図３から明らかなように、Ａｕ又はＡｕを主成分とする金属バンプの再結晶温度よりも高い温度、つまり約２００度よりも高い温度にパッケージを加熱した状態で、弾性表面波素子２ａを搭載すると、約５０％以上の焦電破壊が発生していることが分かる。一方で、加熱するパッケージの温度が約２００度では弾性表面波素子の焦電破壊発生率が約１３％に、約１７０度では０％にまで低下する。
【００３０】
焦電破壊は、パッケージの直上に弾性表面波素子を位置させてから実装するまでの間に、２００度よりも高い温度に熱したパッケージの温度の影響を受けて、弾性表面波素子の圧電基板の温度が常温からパッケージの温度まで急速に上がるため、弾性表面波素子の圧電基板の温度勾配（単位時間あたりの温度変化）により、圧電基板の焦電性によってくし型電極部の電極指間に電荷が発生することが原因で発生する。そこで、パッケージを熱する温度をある程度低い温度、特にＡｕ又はＡｕを主成分とする金属バンプの再結晶温度よりも低い温度にすると、パッケージの直上に弾性表面波素子を位置させてから実装するまでの間の圧電基板の温度勾配は緩やかなものとなり、くし型電極部の電極指間に電荷が発生しにくくなるために、図３のような関係となる。
【００３１】
なお、焦電破壊は、電極指のギャップの平均が小さい、つまり、電極指のギャップが狭いほど発生しやすくなる。弾性表面波素子では中心周波数が高くなるにつれて、電極指のギャップ及び電極指ピッチが狭くなる。例えば、中心周波数が８００MHｚの場合、電極指のギャップは約１．５μｍ、電極指ピッチは約２．５μｍであるが、中心周波数が１GHｚになると、電極指のギャップは約０．５〜１．０μｍ、電極指ピッチは約２μｍになる。更に、中心周波数が２GHｚになると、電極指のギャップは約０．２〜０．６μｍ、電極指ピッチは約１．１μｍになる。
【００３２】
上述のように、図３は電極指のギャップの平均が約１μｍの弾性表面波素子を用いた場合を示しているが、中心周波数が２GHｚ以上と高くなると、その分、電極指のギャップ及び電極指ピッチが狭くなり、パッケージの加熱温度に対する焦電破壊発生率は高くなることになる。よって、本発明のように、弾性表面波素子を実装する際のパッケージの温度を、Ａｕ又はＡｕを主成分とする金属バンプの再結晶温度よりも低くすることで焦電破壊を防止することは、弾性表面波素子の中心周波数が高くなるほど、大きな効果が得られることになる。
【００３３】
次に、図１（ｃ）に示すように、Ａｕ又はＡｕを主成分とする金属バンプ３の再結晶温度よりも高い温度にパッケージ４を熱した上で、相対的に低い周波数特性を有する弾性表面波素子２ｂのくし型電極部２２などが形成された弾性表面波伝播面をパッケージ４のダイアタッチ面に対向させ、パッケージ４をワーク（図示せず）で支持した状態でボンディングツール５によって弾性表面波素子２ｂの裏面に超音波と荷重とを同時に印加することで、パッケージ４に搭載する。
【００３４】
パッケージ４は、Ａｕ又はＡｕを主成分とする金属バンプ３の再結晶温度である約２００度よりも高い温度に熱されているため、金属バンプ３の固相拡散・塑性変形が促進されて、接合が良くなる。
【００３５】
このとき、Ａｕ又はＡｕを主成分とする金属バンプ３の再結晶温度よりも高い温度、つまり約２００度以上にパッケージを熱しても、相対的に高い周波数特性を有する弾性表面波素子２ａはパッケージ４のアースと導通しているので（図示せず）、圧電基板の焦電性によって発生した電荷はパッケージに移り、くし型電極部の電極指間に放電は発生せず、焦電破壊が起こらない。一方の相対的に低い周波数特性を有する弾性表面波素子２ｂは、電極指のギャップの平均が相対的に広く、約１μｍよりも広いので、くし型電極部の電極指間の電荷はそもそも発生しにくく、焦電破壊は起こらない。
【００３６】
相対的に高い周波数特性を有する弾性表面波素子２ａは、当初Ａｕ又はＡｕを主成分とする金属バンプ３の再結晶温度である約２００度よりも低い温度である約１７０度で接合されるので金属バンプ３の固相拡散・塑性変形が十分ではなく、図４に示すように、パッケージ４との接合強度は弱いものであるが、相対的に低い周波数特性の弾性表面波素子２ｂを搭載する際に、金属バンプ３の再結晶温度である約２００度よりも高い温度までパッケージ４を熱するので、それと共に、相対的に高い周波数特性の弾性表面波素子２ａのパッケージ４との接合界面も温度が上がり、金属バンプ３の固相拡散が促進されるために接合が良くなる。
【００３７】
最後に、図１（ｄ）に示すように、パッケージ４を気密封止するために、Ｆｅ−Ｎｉ合金又はＦｅを主成分とする合金からなるリッド４３を、半田からなる接合部材４２により接合する。これにより、弾性表面波装置１を得る。
【００３８】
なお、本実施例では、Ｆｅ−Ｎｉ合金又はＦｅを主成分とする合金からなるリッド４３を用いたが、パッケージ４を気密封止することができるのであれば、樹脂で形成されていてもよい。また、本実施例では半田からなる接合部材４２を用いてリッドを接合したが、樹脂を用いてもよい。
【００３９】
本実施例では、互いに周波数の異なる２つの弾性表面波素子を用いたが、本発明はこれに限らず、周波数の異なる複数の弾性表面波素子を用意し、先に相対的に高い周波数特性を有する少なくとも１つの弾性表面波素子を金属バンプの再結晶温度よりも低い温度でパッケージにフリップチップボンディング法で搭載した後、残余の相対的に低い周波数特性を有する弾性表面波素子を金属バンプの再結晶温度よりも高い温度で搭載してもよい。
【００４０】
（実施の形態２）図５は本発明の第二の実施例における弾性表面波素子を実装する工程図である。なお、実施の形態１と同様の要素については、同様の記号を用い、説明は省略する。
【００４１】
図５（ａ）に示すように、実施の形態１と同様に複数層のアルミナセラミックシートを積層することで凹部形状に形成されてなるパッケージ４を用意する。パッケージ４のダイアタッチ面には該パッケージに搭載される弾性表面波素子と金属バンプを介して電気的に接続される複数の電極ランド及び配線が、パッケージの裏面から側面には外部端子が形成されている。
【００４２】
パッケージと共に、中心周波数が１ＧＨｚである、電極指のギャップの平均ピが約２μｍである弾性表面波素子２０を用意する。この弾性表面波素子２０は、図２に示すものと同様に、圧電基板２１の一方主面にＡｌ又はＡｌを主成分とする合金により形成されている、くし型電極部２２、反射器２３、配線２４、電極パッド２５を有し、電極パッド上には、Ａｕ又はＡｕを主成分とする金属バンプ３をボールボンディング法によって形成する。
【００４３】
次に、図５（ｂ）に示すように、弾性表面波素子２０のくし型電極部２２などが形成された弾性表面波伝播面をパッケージ４のダイアタッチ面に対向させると共に、パッケージをワーク（図示せず）で支持した状態で、ボンディングツール５によって弾性表面波素子２０の裏面に超音波と荷重とを同時に印加することで、パッケージ４に搭載する。このとき、パッケージ４はＡｕ又はＡｕを主成分とする金属バンプ３の再結晶温度である約２００度よりも低い温度である１７０度に熱されている。これによって、弾性表面波素子２０の複数の電極パッド２５とこれに対応するパッケージ４の各電極ランドとをＡｕ又はＡｕを主成分とする金属バンプ３で接合して、弾性表面波素子２０をパッケージ４に接続・固定する共に、電気的に接続する。このとき、弾性表面波素子２０で焦電破壊が起こらないのは、実施の形態１の場合と同様の原理による。
【００４４】
次に、図５（ｃ）に示すように、弾性表面波素子２０を搭載したパッケージ４を、Ａｕ又はＡｕを主成分とする金属バンプ３の再結晶温度である約２００度よりも高い温度まで加熱し、熱処理を行う。弾性表面波素子２０のパッケージ４との接合強度は、当初、Ａｕ又はＡｕを主成分とする金属バンプ３の再結晶温度よりも低い温度で搭載されたために弱いものであったが、この熱処理によって、弾性表面波素子２０のパッケージ４との接合界面も温度が上がり、金属バンプ３の固相拡散が促進されるために接合が良くなる。
【００４５】
最後に、図５（ｄ）に示すように、パッケージ４を気密封止するために、Ｆｅ−Ｎｉ合金又はＦｅを主成分とする合金からなるリッド４３を、半田からなる接合部材４２により接合する。これにより、弾性表面波装置１０を得る。
【００４６】
【発明の効果】
以上のように、本発明の第一の弾性表面波装置の製造方法によると、圧電基板上に形成された少なくとも一つのくし型電極部を有する複数の弾性表面波素子を、Ａｕめっきされた電極ランドが形成されたパッケージに、Ａｕ若しくはＡｕ合金からなる金属バンプを用いて超音波と荷重を同時に印加するフリップチップボンディング法により搭載する際、電極指ギャップの平均が小さいために焦電破壊が起こりやすい、相対的に高い周波数特性を有する弾性表面波素子を金属バンプの再結晶温度よりも低い温度で先に搭載して、相対的に高い周波数特性を有する弾性表面波素子をパッケージのアースと導通させることで、相対的に低い周波数特性を有する弾性表面波素子を後で搭載する際に、金属バンプの再結晶温度よりも高い温度までパッケージを熱しても、相対的に高い周波数特性を有する弾性表面波素子はパッケージのアースと導通されているために圧電基板の焦電性によって発生した電荷はパッケージに移り、くし型電極部の電極指間の放電は発生せず、焦電破壊を防止することができると共に、パッケージと弾性表面波素子の密着強度を十分なものにすることができる。
【図面の簡単な説明】
【図１】本発明の第一の実施例における弾性表面波素子を実装する工程図である。
【図２】本発明に用いる弾性表面波素子のくし型電極の平面図である。
【図３】本発明におけるパッケージの加熱温度と焦電破壊発生率の関係を示す図である。
【図４】本発明におけるパッケージに搭載された弾性表面波素子の金属バンプシェア強度を示す図である。
【図５】本発明の第二の実施例における弾性表面波素子を実装する工程図である。
【図６】一般的な弾性表面波素子のくし型電極部の拡大平面図である。
【符号の説明】
１、１０ 弾性表面波装置
２、２０ 弾性表面波素子
３ 金属バンプ
４ パッケージ
５ ボンディングツール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface acoustic wave device, and more particularly to a surface acoustic wave device in which a surface acoustic wave element is mounted in a package.
[0002]
[Prior art]
In recent years, as mobile communication devices such as automobile phones and mobile phones have become smaller, lighter, and higher in frequency, small and light surface acoustic wave devices (surface acoustic wave filters) have been used as filters mounted on these mobile communication devices. ) Is frequently used. In particular, since mobile phones are particularly required to be small and light, surface acoustic wave devices to be mounted are also required to be small and light.
[0003]
In order to meet such demands, the surface acoustic wave device, when mounting a surface acoustic wave element on a package, uses a flip-chip bonding method using a metal bump mainly composed of Au or Au from a conventional wire bonding method. It is moving to.
[0004]
When a surface acoustic wave element is mounted on a package by a flip chip bonding method, first, Au or a metal bump mainly composed of Au is formed on the electrode pad of the surface acoustic wave element by a ball bonding method. Next, the surface acoustic wave propagation surface on which the comb electrode portion of the surface acoustic wave element is formed is opposed to the die attach surface of the package, and an ultrasonic wave and a load are simultaneously applied to the back surface of the surface acoustic wave element by a bonding tool. To do. As a result, each electrode pad of the surface acoustic wave element and each electrode land of the package corresponding to the surface pad are joined by metal bumps mainly composed of Au or Au, and the surface acoustic wave element is connected and fixed to the package.
[0005]
Conventionally, when an ultrasonic wave and a load are simultaneously applied to the back surface of a surface acoustic wave element by a bonding tool, bonding is performed in a state where the package is heated to a temperature higher than the recrystallization temperature of Au or a metal bump mainly composed of Au. When bonding is performed using a tool and simultaneously applying ultrasonic waves, load, and heat, solid-phase diffusion and composition deformation of the metal bumps are promoted to improve bonding. For this reason, the surface acoustic wave element is mounted by heating the package to a temperature higher than 200 ° C. that is the recrystallization temperature of Au or a metal bump containing Au as a main component.
[0006]
Similarly, when two or more surface acoustic wave elements are mounted in one package, the package is heated to a temperature higher than 200 ° C. which is the recrystallization temperature of metal bumps mainly composed of Au or Au. In addition, using a bonding tool, ultrasonic waves, loads, and heat were simultaneously applied to all the surface acoustic wave elements to be mounted to join the package.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-122072
[Problems to be solved by the invention]
However, with higher frequencies, a surface acoustic wave device having a high frequency characteristic, particularly a center frequency of 1 GHz or higher, is packaged at a temperature higher than 200 ° C., which is the recrystallization temperature of metal bumps mainly composed of Au or Au. When a bonding tool is used in a heated state and ultrasonic waves, load, and heat are applied to join the package, electrode finger destruction of the surface acoustic wave element occurs.
[0009]
This is because the temperature of the piezoelectric substrate of the surface acoustic wave element is affected by the temperature of the package heated to a temperature higher than 200 degrees between the time when the surface acoustic wave element is positioned immediately above the package and the time of mounting. Since the temperature rapidly rises from room temperature to the temperature of the heated package, due to this steep temperature gradient (temperature change per unit time), electric charges are generated between the electrode fingers of the comb electrode part due to the pyroelectricity of the piezoelectric substrate, This is because a short circuit occurred and pyroelectric breakdown of the electrode fingers occurred.
[0010]
Here, pyroelectricity means that a piezoelectric substrate such as lithium tantalate (LiTaO 3 ) or lithium niobate (LiNbO 3 ) has one end that is positively charged when the crystal is heated, and the other end is negatively charged. When the temperature is different, the degree of expansion of the substrate is different, so a difference appears in the internal spontaneous polarization, and the effect is that charges are generated on the substrate surface.
[0011]
Further, pyroelectric breakdown is a phenomenon in which a surface potential is generated in the surface acoustic wave element due to the pyroelectric property of the piezoelectric substrate described above due to the influence of a steep temperature gradient (temperature change per time). When the electric charge increases, it is discharged between the electrode fingers that are close to each other, and due to the effect of the heat, the electrode fingers are burnt (melted) and deformed, or they must be non-contacting, that is, they are in contact with each other. This refers to electrode destruction caused by pyroelectricity of the piezoelectric substrate.
[0012]
Since the electric charge generated by the pyroelectric property of the piezoelectric substrate is proportional to the temperature gradient, pyroelectric breakdown is more likely to occur as the substrate temperature rapidly rises from room temperature to a higher temperature. In addition, the shorter the gap between the electrode fingers, the easier the short circuit due to the generated charges. In particular, in a surface acoustic wave device having high frequency characteristics, the electrode finger pitch is narrowed, so that the gap between the electrode fingers is also narrowed. In particular, since the average gap between electrode fingers of a surface acoustic wave element having a center frequency of 1 GHz or more is as narrow as about 1 μm or less, pyroelectric breakdown is likely to occur. Here, as shown in FIG. 6, in the comb-like electrode constituting the comb-shaped electrode portion, the electrode finger pitch is opposite to the electrode finger of one comb-like electrode, and the electrode finger of the other comb-like electrode is opposed. The gap between the electrode fingers is the gap between the electrode fingers of one comb-like electrode and the electrode fingers of the other comb-like electrode adjacent to the electrode finger.
[0013]
The surface acoustic wave manufacturing method of the present invention has been made in view of the above-described problems, and solves these problems. Particularly, a surface acoustic wave element used in a high frequency band having a center frequency of 1 GHz or more is used as a pyroelectric material. An object of the present invention is to provide a method of manufacturing a surface acoustic wave device that can be bonded to a package with good adhesion strength while preventing breakage.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, according to the first method of manufacturing a surface acoustic wave device of the present invention, a plurality of surface acoustic wave elements having at least one comb-shaped electrode portion formed on a piezoelectric substrate are Au-plated. A method of manufacturing a surface acoustic wave device to be mounted by a flip chip bonding method in which ultrasonic waves and a load are simultaneously applied to a package in which electrode lands are formed using metal bumps made of Au or Au alloy, At least one of the surface acoustic wave elements has an elastic surface in which the average of the gaps of the electrode fingers constituting the comb-shaped electrode part is smaller than the remaining ones, and the average of the gaps of the electrode fingers constituting the comb-shaped electrode part is smaller after wave element mounted on the package at a temperature below the recrystallization temperature of the metal bumps, the residual surface acoustic wave device than the recrystallization temperature of the metal bumps Characterized in that mounted on the package at a high temperature.
[0015]
As a result, first, a surface acoustic wave device having a relatively high frequency characteristic, in which pyroelectric breakdown is likely to occur due to the small gap between the electrode fingers, is first mounted at a temperature lower than the recrystallization temperature of the metal bump. To connect to the ground of the package. At this time, since the temperature of the package is lower than the recrystallization temperature of the metal bump, the temperature change of the piezoelectric substrate of the surface acoustic wave element between the time when the surface acoustic wave element is mounted immediately after the package is mounted, That is, since the temperature gradient (temperature change per unit time) is small, pyroelectric breakdown does not occur. Next, when a surface acoustic wave element having a relatively low frequency characteristic is mounted, even if the package is heated to a temperature higher than the recrystallization temperature of the metal bump, the elastic surface having a relatively high frequency characteristic Since the wave element is electrically connected to the ground of the package, the charge generated by the pyroelectric property of the piezoelectric substrate is transferred to the package, and no discharge is generated between the electrode fingers of the comb-shaped electrode portion, so that pyroelectric breakdown does not occur.
[0016]
The average strength of the electrode finger gap is small, that is, the bonding strength with the surface acoustic wave device package having a relatively high frequency characteristic is weak because it is bonded at a low temperature that does not cause pyroelectric breakdown. . However, when the surface acoustic wave device having the remaining relatively low frequency characteristics is subsequently mounted, the package is heated to a temperature higher than the recrystallization temperature of the metal bump, and accordingly, a relatively high frequency is also provided. The temperature of the bonding interface of the surface acoustic wave element having characteristics also rises, and solid phase diffusion of the metal bumps is promoted, so that bonding is improved.
[0017]
Note that the average of the gaps between the electrode fingers means the electrode fingers of one comb-like electrode constituting all the comb-shaped electrode portions of the surface acoustic wave element and the other comb-like electrode adjacent to the electrode finger. It means the average distance between electrode fingers.
[0019]
As a result, a surface acoustic wave element having a high frequency characteristic that is prone to pyroelectric breakdown due to a small gap between electrode fingers is mounted at a temperature lower than the recrystallization temperature of the metal bump, and the surface acoustic wave element is mounted. Even if heat treatment is performed later at a temperature higher than the recrystallization temperature of the metal bump, the surface acoustic wave element is electrically connected to the ground of the package. The charge is transferred to the package, no discharge is generated between the electrode fingers of the comb-shaped electrode portion, and pyroelectric breakdown does not occur.
[0020]
The bonding strength of the surface acoustic wave element is weak because it is initially bonded at a temperature lower than the recrystallization temperature of the metal bump, but after mounting it is heat treated at a temperature higher than the recrystallization temperature of the bump, The temperature at the bonding interface of the surface acoustic wave element rises and solid phase diffusion of the metal bumps is promoted, so that bonding is improved.
[0022]
Moreover, it is preferable that the recrystallization temperature of a metal bump is about 200 degree | times.
[0023]
The average gap between the electrode fingers of the surface acoustic wave element is preferably about 1 μm or less.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1) FIG. 1 is a process diagram for mounting a surface acoustic wave element according to the first embodiment of the present invention, FIG. 2 is a plan view of a comb-shaped electrode of the surface acoustic wave element used in the present invention, and FIG. The figure which shows the relationship between the heating temperature of a package and the pyroelectric breakdown incidence in this invention, FIG. 4 is a figure which shows the metal bump shear strength of the surface acoustic wave element mounted in the package in this invention.
[0025]
First, as shown in FIG. 1A, a package 4 formed in a concave shape by preparing a plurality of layers of alumina ceramic sheets is prepared. Although the die attach surface of the package 4 is not shown, a plurality of electrode lands and wirings that are electrically connected to the surface acoustic wave element 2 mounted on the package 4 via the metal bumps 3 are formed. Au plated. Since the plurality of electrode lands and wiring are plated with Au, when the metal bump 3 is made of Au or an alloy containing Au as a main component, it is particularly easy to join. Further, external terminals 41 are formed from the back surface to the side surface of the package 4. The package 4 may be formed of resin instead of ceramic.
[0026]
Two surface acoustic wave elements 2 a and 2 b having different frequency characteristics are prepared together with the package 4. The surface acoustic wave element 2a has a relatively high frequency characteristic, that is, the surface acoustic wave element has a frequency characteristic higher than 2b, and the surface acoustic wave element 2b has a relatively low frequency characteristic, that is, the surface acoustic wave element is It has a frequency characteristic lower than 2a. More specifically, the surface acoustic wave device having relatively high frequency characteristics has a center frequency of 1 GHz, an average of electrode finger gaps of about 1 μm, and an electrode finger pitch of about 2 μm. A surface acoustic wave device having a relatively low frequency characteristic has a center frequency of 800 MHz, an average gap between electrode fingers of about 1.5 μm, and an electrode finger pitch of 2.5 μm.
[0027]
As shown in FIG. 2, the surface acoustic wave elements 2a and 2b are made of Al or an alloy containing Al as a main component on one main surface of the piezoelectric substrate 21, and include a comb-shaped electrode portion 22, a reflector 23, and a wiring. 24 and electrode pads 25. As the piezoelectric substrate 21, lithium tantalate (LiTaO 3 ), lithium niobate (LiNbO 3 ), or the like is used. On the electrode pad 25, Au or a metal bump 3 containing Au as a main component is formed by a ball bonding method. As the metal bump 3, Au is preferably used because it has good bondability with Al as an electrode material, is stable, and does not corrode or oxidize.
[0028]
Next, as shown in FIG. 1 (b), a surface acoustic wave element 2a having a relatively high frequency characteristic is prepared, and the surface acoustic wave propagation in which the surface electrode element 2a is formed with a comb-shaped electrode portion or the like is prepared. By applying the ultrasonic wave and the load simultaneously to the back surface of the surface acoustic wave element 2a by the bonding tool 5 with the surface opposed to the die attach surface of the package and the package 4 supported by a work (not shown). Mounted on the package 4. At this time, the package 4 is heated to 170 degrees which is a temperature lower than about 200 degrees which is the recrystallization temperature of Au or the metal bump 3 containing Au as a main component. As a result, the plurality of electrode pads 25 of the surface acoustic wave element 2a and the corresponding electrode lands of the package 4 are joined via the metal bumps 3 whose main component is Au or Au, and have relatively high frequency characteristics. The surface acoustic wave element 2a having the above is connected and fixed to the package 4 and is electrically connected.
[0029]
FIG. 3 shows the relationship between the heating temperature of the package and the rate of occurrence of pyroelectric breakdown of the surface acoustic wave device when the surface acoustic wave device having an average electrode finger gap of about 1 μm is mounted on the package. As is apparent from FIG. 3, the surface acoustic wave element 2a is mounted in a state where the package is heated to a temperature higher than the recrystallization temperature of Au or a metal bump mainly composed of Au, that is, a temperature higher than about 200 degrees. Then, it can be seen that pyroelectric breakdown of about 50% or more occurs. On the other hand, the pyroelectric breakdown occurrence rate of the surface acoustic wave element is reduced to about 13% when the temperature of the package to be heated is about 200 degrees, and is reduced to 0% at about 170 degrees.
[0030]
The pyroelectric breakdown is influenced by the temperature of the package heated to a temperature higher than 200 degrees between the time when the surface acoustic wave element is placed immediately above the package and the time when the surface acoustic wave element is mounted. Since the temperature of the substrate rapidly rises from room temperature to the package temperature, the temperature gradient of the piezoelectric substrate of the surface acoustic wave element (temperature change per unit time) causes the pyroelectricity of the piezoelectric substrate between the electrode fingers of the comb-shaped electrode section. It is caused by the generation of electric charges. Therefore, if the temperature at which the package is heated is set to a certain low temperature, particularly lower than the recrystallization temperature of the metal bumps mainly composed of Au or Au, the surface acoustic wave element is positioned immediately above the package and then mounted. The temperature gradient of the piezoelectric substrate in between becomes gentle, and it becomes difficult for charges to be generated between the electrode fingers of the comb-shaped electrode portion, so that the relationship shown in FIG. 3 is obtained.
[0031]
Note that pyroelectric breakdown is more likely to occur as the average of the electrode finger gap is smaller, that is, as the electrode finger gap is narrower. In the surface acoustic wave device, the gap between the electrode fingers and the electrode finger pitch become narrower as the center frequency becomes higher. For example, when the center frequency is 800 MHz, the gap between the electrode fingers is about 1.5 μm and the electrode finger pitch is about 2.5 μm. However, when the center frequency is 1 GHz, the gap between the electrode fingers is about 0.5 to 1. 0 μm, and the electrode finger pitch is about 2 μm. Furthermore, when the center frequency is 2 GHz, the gap between the electrode fingers is about 0.2 to 0.6 μm, and the electrode finger pitch is about 1.1 μm.
[0032]
As described above, FIG. 3 shows a case where a surface acoustic wave element having an average electrode finger gap of about 1 μm is used. However, when the center frequency becomes higher than 2 GHz, the electrode finger gap and the electrode are correspondingly increased. The finger pitch becomes narrow, and the pyroelectric breakdown occurrence rate with respect to the heating temperature of the package becomes high. Therefore, as in the present invention, it is possible to prevent pyroelectric breakdown by making the temperature of the package when mounting the surface acoustic wave element lower than the recrystallization temperature of the metal bump mainly composed of Au or Au. As the center frequency of the surface acoustic wave element increases, a greater effect is obtained.
[0033]
Next, as shown in FIG. 1C, after the package 4 is heated to a temperature higher than the recrystallization temperature of Au or the metal bump 3 containing Au as a main component, elasticity having a relatively low frequency characteristic is obtained. The surface acoustic wave propagation surface on which the comb-shaped electrode portion 22 and the like of the surface acoustic wave element 2b are formed is opposed to the die attach surface of the package 4, and the package 4 is supported by a work (not shown) and is elasticized by the bonding tool 5. The ultrasonic wave and the load are simultaneously applied to the back surface of the surface acoustic wave element 2b, so that the surface wave element 2b is mounted on the package 4.
[0034]
Since the package 4 is heated to a temperature higher than about 200 ° C., which is the recrystallization temperature of the metal bump 3 mainly composed of Au or Au, solid phase diffusion / plastic deformation of the metal bump 3 is promoted, Bonding is improved.
[0035]
At this time, even if the package is heated to a temperature higher than the recrystallization temperature of Au or the metal bump 3 containing Au as a main component, that is, about 200 degrees or more, the surface acoustic wave element 2a having a relatively high frequency characteristic is packaged. 4 (not shown), the electric charge generated by the pyroelectric property of the piezoelectric substrate is transferred to the package, and no electric discharge is generated between the electrode fingers of the comb-shaped electrode portion, causing pyroelectric breakdown. Absent. On the other hand, the surface acoustic wave element 2b having a relatively low frequency characteristic has a relatively wide gap between electrode fingers, which is wider than about 1 μm, so that charges between the electrode fingers of the comb-shaped electrode portion are originally generated. It is difficult to cause pyroelectric breakdown.
[0036]
The surface acoustic wave element 2a having a relatively high frequency characteristic is bonded at about 170 degrees which is lower than about 200 degrees which is the recrystallization temperature of the metal bump 3 which is initially composed of Au or Au as a main component. As shown in FIG. 4, the metal bump 3 is not sufficiently solid-phase diffused and plastically deformed, and the bonding strength with the package 4 is weak, but a surface acoustic wave element 2b having a relatively low frequency characteristic is mounted. At this time, the package 4 is heated to a temperature higher than about 200 ° C. which is the recrystallization temperature of the metal bump 3, and at the same time, a bonding interface between the surface acoustic wave element 2 a having relatively high frequency characteristics and the package 4 is also formed. The temperature rises and the solid phase diffusion of the metal bumps 3 is promoted, so that the bonding is improved.
[0037]
Finally, as shown in FIG. 1D, in order to hermetically seal the package 4, a lid 43 made of an Fe—Ni alloy or an alloy containing Fe as a main component is joined by a joining member 42 made of solder. . Thereby, the surface acoustic wave device 1 is obtained.
[0038]
In this embodiment, the lid 43 made of an Fe—Ni alloy or an alloy containing Fe as a main component is used. However, as long as the package 4 can be hermetically sealed, it may be formed of a resin. . In this embodiment, the lid is bonded using the bonding member 42 made of solder, but a resin may be used.
[0039]
In this embodiment, two surface acoustic wave elements having different frequencies are used. However, the present invention is not limited to this, and a plurality of surface acoustic wave elements having different frequencies are prepared, and a relatively high frequency characteristic is first obtained. After mounting the surface acoustic wave element having at least one surface acoustic wave element on the package at a temperature lower than the recrystallization temperature of the metal bump by a flip chip bonding method, the surface acoustic wave element having a relatively low frequency characteristic is It may be mounted at a temperature higher than the crystal temperature.
[0040]
(Embodiment 2) FIG. 5 is a process diagram for mounting a surface acoustic wave device according to a second embodiment of the present invention. In addition, about the element similar to Embodiment 1, the same symbol is used and description is abbreviate | omitted.
[0041]
As shown in FIG. 5A, a package 4 is prepared which is formed in a concave shape by laminating a plurality of layers of alumina ceramic sheets as in the first embodiment. The die attach surface of the package 4 has a plurality of electrode lands and wirings electrically connected to the surface acoustic wave element mounted on the package through metal bumps, and external terminals are formed from the back surface to the side surface of the package. ing.
[0042]
Along with the package, a surface acoustic wave device 20 having a center frequency of 1 GHz and an average finger gap gap of about 2 μm is prepared. This surface acoustic wave element 20 has a comb-shaped electrode portion 22, a reflector 23, which is formed of Al or an alloy containing Al as a main component on one main surface of a piezoelectric substrate 21, as shown in FIG. A wiring 24 and an electrode pad 25 are provided, and Au or a metal bump 3 mainly composed of Au is formed on the electrode pad by a ball bonding method.
[0043]
Next, as shown in FIG. 5B, the surface acoustic wave propagation surface on which the comb-shaped electrode portion 22 of the surface acoustic wave element 20 is formed is opposed to the die attach surface of the package 4, and the package is mounted on the workpiece ( While being supported by a bonding tool 5, an ultrasonic wave and a load are simultaneously applied to the back surface of the surface acoustic wave element 20 by the bonding tool 5, so that the package 4 is mounted. At this time, the package 4 is heated to 170 degrees which is a temperature lower than about 200 degrees which is the recrystallization temperature of Au or the metal bump 3 containing Au as a main component. As a result, the plurality of electrode pads 25 of the surface acoustic wave element 20 and the corresponding electrode lands of the package 4 are joined by the metal bumps 3 whose main component is Au or Au, and the surface acoustic wave element 20 is packaged. Connect and fix to 4 and connect electrically. At this time, the pyroelectric breakdown does not occur in the surface acoustic wave element 20 based on the same principle as in the first embodiment.
[0044]
Next, as shown in FIG. 5C, the package 4 on which the surface acoustic wave element 20 is mounted is heated to a temperature higher than about 200 ° C. which is the recrystallization temperature of the metal bump 3 mainly composed of Au or Au. Heat and heat treatment. The bonding strength between the surface acoustic wave element 20 and the package 4 was weak because it was initially mounted at a temperature lower than the recrystallization temperature of the metal bump 3 mainly composed of Au or Au. Further, the temperature of the bonding interface between the surface acoustic wave element 20 and the package 4 also rises, and solid-phase diffusion of the metal bumps 3 is promoted, so that the bonding is improved.
[0045]
Finally, as shown in FIG. 5D, in order to hermetically seal the package 4, a lid 43 made of an Fe—Ni alloy or an alloy containing Fe as a main component is joined by a joining member 42 made of solder. . Thereby, the surface acoustic wave device 10 is obtained.
[0046]
【The invention's effect】
As described above, according to the first method of manufacturing a surface acoustic wave device of the present invention, a plurality of surface acoustic wave elements having at least one comb-shaped electrode portion formed on a piezoelectric substrate are Au-plated electrodes. When mounting on a land-formed package by flip-chip bonding using ultrasonic bumps and metal bumps made of Au or Au alloy at the same time , pyroelectric breakdown occurs because the average electrode finger gap is small. A surface acoustic wave element having a relatively high frequency characteristic, which is easy to mount, is first mounted at a temperature lower than the recrystallization temperature of the metal bump, and the surface acoustic wave element having a relatively high frequency characteristic is electrically connected to the ground of the package. Therefore, when a surface acoustic wave device having a relatively low frequency characteristic is mounted later, the temperature is higher than the recrystallization temperature of the metal bump. Even if the surface is heated, the surface acoustic wave element having a relatively high frequency characteristic is electrically connected to the ground of the package, so that the charge generated by the pyroelectric property of the piezoelectric substrate is transferred to the package, and the comb-shaped electrode portion Discharge between electrode fingers does not occur, pyroelectric breakdown can be prevented, and the adhesion strength between the package and the surface acoustic wave element can be made sufficient.
[Brief description of the drawings]
FIG. 1 is a process diagram for mounting a surface acoustic wave device according to a first embodiment of the present invention.
FIG. 2 is a plan view of a comb electrode of a surface acoustic wave element used in the present invention.
FIG. 3 is a diagram showing the relationship between the heating temperature of a package and the rate of occurrence of pyroelectric breakdown in the present invention.
FIG. 4 is a diagram showing a metal bump shear strength of a surface acoustic wave element mounted on a package according to the present invention.
FIG. 5 is a process diagram for mounting the surface acoustic wave device according to the second embodiment of the present invention.
FIG. 6 is an enlarged plan view of a comb-shaped electrode portion of a general surface acoustic wave element.
[Explanation of symbols]
1, 10 Surface acoustic wave device 2, 20 Surface acoustic wave element 3 Metal bump 4 Package 5 Bonding tool

Claims (3)

圧電基板上に形成された少なくとも一つのくし型電極部を有する複数の弾性表面波素子を、Ａｕめっきされた電極ランドが形成されたパッケージに、Ａｕ若しくはＡｕ合金からなる金属バンプを用いて超音波と荷重を同時に印加するフリップチップボンディング法により搭載する弾性表面波装置の製造方法であって、
前記複数の弾性表面波素子のうち少なくとも一つは、残余のものより、前記くし型電極部を構成する電極指のギャップの平均が小さく、
該くし型電極部を構成する電極指のギャップの平均が小さい弾性表面波素子を前記金属バンプの再結晶温度よりも低い温度で前記パッケージに搭載した後、残余の弾性表面波素子を前記金属バンプの再結晶温度よりも高い温度で前記パッケージに搭載することを特徴とする、弾性表面波装置の製造方法。A plurality of surface acoustic wave elements each having at least one comb-shaped electrode portion formed on a piezoelectric substrate are ultrasonicated using a metal bump made of Au or an Au alloy on a package formed with an Au-plated electrode land. And a method of manufacturing a surface acoustic wave device to be mounted by a flip chip bonding method in which a load is applied simultaneously,
At least one of the plurality of surface acoustic wave elements has an average gap between electrode fingers constituting the comb-shaped electrode portion smaller than the rest,
After mounting the surface acoustic wave device having a small average gap between the electrode fingers constituting the comb-shaped electrode portion on the package at a temperature lower than the recrystallization temperature of the metal bump, the remaining surface acoustic wave device is mounted on the metal bump. A method for manufacturing a surface acoustic wave device, wherein the surface acoustic wave device is mounted on the package at a temperature higher than the recrystallization temperature. 前記金属バンプの再結晶温度が約２００度であることを特徴とする、請求項１に記載の弾性表面波装置の製造方法。2. The method of manufacturing a surface acoustic wave device according to claim 1, wherein a recrystallization temperature of the metal bump is about 200 degrees. 前記くし型電極部を構成する電極指のギャップの平均が小さい弾性表面波素子のくし型電極部を構成する電極指のギャップの平均が約１μｍ以下であることを特徴とする、請求項１または２のいずれかに記載の弾性表面波装置の製造方法。The average of the gaps of the electrode fingers constituting the comb-shaped electrode part of the surface acoustic wave element having a small average of the gaps of the electrode fingers constituting the comb-shaped electrode part is about 1 μm or less, or 3. A method for producing a surface acoustic wave device according to any one of 2 above.
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KR20170054270A (en) * 2015-10-30 2017-05-17 인피니온 테크놀로지스 아게 Multi-die package having different types of semiconductor dies attached to the same thermally conductive flange
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EP1788385A4 (en) 2004-09-10 2014-04-09 Murata Manufacturing Co Sensor for detecting substance in liquid and device for detecting substance in liquid employing same

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US10468399B2 (en) 2015-03-31 2019-11-05 Cree, Inc. Multi-cavity package having single metal flange
US11437362B2 (en) 2015-03-31 2022-09-06 Wolfspeed, Inc. Multi-cavity package having single metal flange
KR20170054270A (en) * 2015-10-30 2017-05-17 인피니온 테크놀로지스 아게 Multi-die package having different types of semiconductor dies attached to the same thermally conductive flange
US9997476B2 (en) 2015-10-30 2018-06-12 Infineon Technologies Ag Multi-die package having different types of semiconductor dies attached to the same thermally conductive flange
KR101875212B1 (en) * 2015-10-30 2018-08-02 인피니온 테크놀로지스 아게 Multi-die package having different types of semiconductor dies attached to the same thermally conductive flange
US11004808B2 (en) 2015-10-30 2021-05-11 Cree, Inc. Package with different types of semiconductor dies attached to a flange

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