JP3961267B2

JP3961267B2 - Crystal device

Info

Publication number: JP3961267B2
Application number: JP2001347446A
Authority: JP
Inventors: 卓也大内
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2001-11-13
Filing date: 2001-11-13
Publication date: 2007-08-22
Anticipated expiration: 2021-11-13
Also published as: JP2003152495A

Description

【０００１】
【発明の属する技術分野】
本発明は、コンピュータ等の情報処理装置や携帯電話等の電子装置において、時間および周波数の高精度の基準源として使用される温度補償型の水晶デバイスに関するものである。
【０００２】
【従来の技術】
コンピュータ等の情報処理装置や携帯電話等の電子装置において時間および周波数の高精度の基準源として使用される温度補償型の水晶デバイスは、一般に、四角板状の水晶基板に電圧印加用の電極を形成して成る水晶振動子と、この水晶振動子の温度補償を行なう半導体素子とを、水晶振動子収納用パッケージ内に気密に収容することによって形成されている。
【０００３】
前記水晶振動子収納用パッケージは、一般に、酸化アルミニウム質焼結体等の電気絶縁材料から成り、上面中央部に水晶振動子を収容する空所を形成するための凹部を、下面中央部に半導体素子を収容する空所となる凹部を、それぞれ有するとともに、各凹部表面から外表面にかけて導出された、タングステン、モリブデン等の高融点金属等の金属材料から成る配線層を有する基体と、鉄−ニッケル−コバルト合金、鉄−ニッケル合金等の金属材料、または酸化アルミニウム質焼結体等のセラミックス材料から成る蓋体とから構成されている。
【０００４】
そして、水晶振動子の電極を基体上面の凹部内表面に露出する配線層及びその周辺の基体表面に固定材を介して取着することにより、水晶振動子を凹部内に接着固定するとともに配線層に電気的に接続し、また、基体下面の凹部内に半導体素子を収容するとともに半導体素子の電極を配線層に電気的に接続し、しかる後、基体の上面に蓋体を接着材による接着やシーム溶接等の接合手段により取着して基体と蓋体とから成る容器内部に水晶振動子を気密に収容するとともに基体下面の凹部内に収容した半導体素子を蓋体や封止用樹脂で封止することによって製品としての水晶デバイスが完成する。
【０００５】
なお、水晶振動子を取着するための固定材としては、一般に、エポキシ樹脂等の有機樹脂と、銀粉末等の導電性粉末とを主材として混合して成る導電性接着材が使用されている。
【０００６】
また、蓋体を基体にシーム溶接で取着する場合、通常、予め基体の凹部周囲に枠状のロウ付け用メタライズ層を形成しておくとともにこのメタライズ層に金属枠体をロウ付けし、金属枠体に蓋体をシーム溶接する方法が用いられる。
【０００７】
更に前記水晶デバイスの外部電気回路基板への実装は、基体の外表面に導出された配線層を外部電気回路基板の配線導体に半田等の導電性接続材を介して接続することによって行われ、水晶振動子は配線層を介し外部電気回路に電気的に接続されるとともに外部電気回路から印加される電圧に応じて所定の周波数で振動し、基準信号を外部電気回路に供給する。
【０００８】
【発明が解決しようとする課題】
しかしながら、従来の水晶デバイスは、基体に形成されている配線層がタングステンやモリブデン、マンガン等の高融点金属材料により形成されており、該タングステン等はその比電気抵抗が５．４μΩ・ｃｍ（２０℃）以上と高いことから配線層に水晶振動子の基準信号や半導体素子の駆動信号を伝搬させた場合、基準信号や駆動信号に大きな減衰が生じ、基準信号や駆動信号を外部電気回路や水晶振動子と半導体素子との間に正確、かつ確実に伝搬させることができないという欠点を有していた。
【０００９】
本発明は上記欠点に鑑み案出されたものであり、その目的は、基体に搭載した半導体素子により水晶振動子の温度補償を有効に行なうことができ、かつ水晶振動子の基準信号を外部電気回路に正確かつ確実に供給することができる水晶デバイスを提供することにある。
【００１０】
【課題を解決するための手段】
本発明は、上面に水晶振動子の搭載部を有し、該搭載部から外表面にかけて配線層が導出されている基体と、前記搭載部に搭載されている水晶振動子とから成る水晶デバイスであって、前記基体が１０乃至６８ｍｏｌ％のＢａＯ、９乃至５０ｍｏｌ％のＳｎＯ_２、１３乃至７２ｍｏｌ％のＢ_２Ｏ_３から成る酸化物焼結体で、前記配線層が２．５μΩ・ｃｍ以下の比電気抵抗を有する金属材で形成されており、かつ前記搭載部の前記配線層上に、ゴム粒子および導電性粉末を添加したエポキシ樹脂から成り、弾性率が２．４ＧＰａ以下であって、前記基体と前記水晶振動子との間に発生する熱応力によって変形する導電性の支持体が形成されているとともに、該支持体に導電性の固定材を介して、前記水晶振動子が接着固定されていることを特徴とするものである。
【００１２】
本発明の水晶デバイスによれば、基体を１０乃至６８ｍｏｌ％のＢａＯ、９乃至５０ｍｏｌ％のＳｎＯ₂、１３乃至７２ｍｏｌ％のＢ₂Ｏ₃から成る酸化物焼結体で形成し、かかる酸化物焼結体の焼成温度が約８００〜１２００℃と低いことから、基体と同時焼成により形成される配線層を比電気抵抗が２．５μΩ・ｃｍ（２０℃）以下と低い銅や銀、金で形成することができ、その結果、配線層に水晶振動子の基準信号や半導体素子の駆動信号等を伝搬させた場合、基準信号や駆動信号に大きな減衰を生じることはなく、基準信号や駆動信号を外部電気回路や水晶振動子と半導体素子との間に正確、かつ確実に伝搬させることが可能となる。
【００１３】
また本発明の水晶デバイスによれば、基体の搭載部の配線層上に、ゴム粒子および導電性粉末を添加したエポキシ樹脂から成る弾性率が２．４ＧＰａ以下であって、基体と水晶振動子との間に発生する熱応力によって変形する導電性の支持体を被着させるとともに、該支持体に水晶振動子を導電性の固定材で接着固定するようにしたことから、水晶振動子の温度補償を行なう半導体素子が作動時に熱を発生し、その熱が基体と水晶振動子に繰り返し作用して基体と水晶振動子との間に両者の熱膨張係数差に起因する熱応力が繰り返し発生したとしても、その熱応力は支持体を適度に変形させることによって吸収され、水晶振動子の基体に対する固定が破れることはなく、その結果、基体に水晶振動子を長期間にわたり確実、強固に固定することが可能となり、水晶デバイスの長期信頼性を高いものとなすことができる。
【００１４】
【発明の実施の形態】
次に本発明の水晶デバイスについて添付の図面を基にして詳細に説明する。
図１は本発明の水晶デバイスの一実施例を示す断面図であり、図１において、１は基体、２は配線層、３は蓋体である。この基体１と蓋体３とにより形成される容器４内に水晶振動子５を気密に収容するとともに、基体１下面に半導体素子６を搭載収容することにより水晶デバイス７が形成される。
【００１５】
前記基体１は、１０乃至６８ｍｏｌ％のＢａＯ、９乃至５０ｍｏｌ％のＳｎＯ₂、１３乃至７２ｍｏｌ％のＢ₂Ｏ₃から成る酸化物焼結体で形成されており、その上下両面に凹部１ａ、１ｂが設けてあり、上面の凹部１ａ内には水晶振動子５が収容され、下面の凹部１ｂには前記水晶振動子５の温度補償を行なうための半導体素子６がロウ材、ガラス、有機樹脂等の接着材を介して接着固定され、搭載収容される。
【００１６】
また前記基体１は、上下の凹部１ａ、１ｂの表面から外表面にかけて配線層２が導出されており、配線層２の基体１上面側の凹部１ａ表面に露出する部位に水晶振動子５の電極が導電性接着材等の固定材９を介して接着固定され、基体１下面側の凹部１ｂに露出する部位には半導体素子６の電極がボンディングワイヤ等の導電性接続部材１０を介して接続される。
【００１７】
前記酸化物焼結体から成る基体１は、例えば、ＢａＯ、ＳｎＯ₂、Ｂ₂Ｏ₃等の原料粉末にアクリル樹脂を主成分とするバインダー及び分散剤、可塑剤、有機溶媒を加えて泥漿物を作るとともに該泥漿物をドクターブレード法やカレンダーロール法を採用することによってグリーンシート（生シート）となし、しかる後、前記グリーンシートに適当な打ち抜き加工を施すとともにこれを複数枚積層し、約８００〜１２００℃の温度で焼成することによって製作される。
【００１８】
前記基体１はその焼成温度が約８００〜１２００℃と低いことから、基体１と同時焼成により形成される配線層２を比電気抵抗が２．５μΩ・ｃｍ（２０℃）以下と低い銅や銀、金で形成することができ、その結果、配線層２に水晶振動子５の基準信号や半導体素子６の駆動信号を伝搬させた場合、基準信号や駆動信号に大きな減衰が生じることはなく、基準信号や駆動信号を外部電気回路や水晶振動子５と半導体素子６との間に正確、かつ確実に伝搬させることが可能となる。
【００１９】
なお、前記酸化物焼結体は、ＢａＯが１０ｍｏｌ％未満であると誘電損失が大きくなって配線層２を伝搬する電気信号に減衰や遅延を招来してしまい、また６８ｍｏｌ％を超えると基体１の機械的強度が大きく低下してしまう。従って、前記酸化物焼結体はそれを構成するＢａＯの量が１０乃至６８ｍｏｌ％に特定される。
【００２０】
また前記酸化物焼結体はＳｎＯ₂が９ｍｏｌ％未満であると焼結性が低下して機械的強度が不十分となり、また５０ｍｏｌ％を超えると誘電損失が大きくなって配線層２を伝搬する電気信号に減衰や遅延を招来してしまう。従って、前記酸化物焼結体はそれを構成するＳｎＯ₂の量が９乃至５０ｍｏｌ％に特定される。
【００２１】
更に前記酸化物焼結体はＢ₂Ｏ₃が１３ｍｏｌ％未満であると焼成温度が高いものとなって銅等の金属材料からなる配線層２と同時に焼成するのが困難となり、また７２ｍｏｌ％を超えると酸化物焼結体の耐薬品性が低下し水晶デバイスとしての信頼性が低いものとなってしまう。従って前記酸化物焼結体はそれを構成するＢ₂Ｏ₃の量が１３乃至７２ｍｏｌ％に特定される。
【００２２】
また前記基体１に形成されている配線層２は、凹部１ａ、１ｂ内に収容される水晶振動子５および半導体素子６と外部電気回路基板の配線導体とを電気的に接続する作用をなし、例えば、金、銀、銅等の比電気抵抗が２．５μΩ・ｃｍ（２０℃）以下の金属材により形成されており、銅から成る場合であれば、銅粉末に適当な有機溶剤、有機バインダー等を添加混合して得た金属ペーストを、基体１となるグリーンシートの表面にスクリーン印刷法等で所定パターンに印刷塗布しておくことによって形成される。
【００２３】
前記配線層２は、その露出する表面をニッケル、金等の耐食性およびロウ材との濡れ性の良好な金属から成るめっき層（不図示）で被覆しておくと、配線層２の酸化腐食を良好に防止することができるとともに、配線層２に対する半田等のロウ材の濡れ性を良好とすることができ、外部電気回路基板の配線導体に対する配線層２の接続をより一層容易、かつ確実なものとすることができる。従って、前記配線層２は、その露出する表面をニッケル、金等のめっき層、例えば、順次被着された厚み１μｍ〜１０μｍのニッケルまたはニッケル合金めっき層、厚み０．１〜３μｍの金めっき層で被覆しておくことが好ましい。
【００２４】
また前記配線層２の表面をニッケル、金等のめっき層で被覆する場合、その最表面の算術平均粗さ（Ｒａ）を１．５μｍ以下、自乗平均平方根粗さ（Ｒｍｓ）を１．８μｍ以下としておくと最表面の光の反射率が４０％以上となって水晶振動子５の電極を配線層２に固定材９を介して固定する際、および半導体素子６の電極を配線層２にボンディングワイヤ等の導電性接続部材１０を介して電気的接続する際、その位置決め等の作業が容易となる。従って、前記配線層２の表面をニッケル、金等のめっき層で被覆する場合、その最表面の算術平均粗さ（Ｒａ）を１．５μｍ以下、自乗平均平方根粗さ（Ｒｍｓ）を１．８μｍ以下としておくことが好ましい。
【００２５】
更に前記配線層２の表面を被覆するニッケル、金等からなるめっき層の最表面の算術平均粗さ（Ｒａ）を１．５μｍ以下、自乗平均平方根粗さ（Ｒｍｓ）を１．８μｍ以下とするには配線層２を従来周知のワット浴にイオウ化合物等の光沢剤を添加した電解ニッケルめっき液に浸漬して配線層２の表面にニッケルめっき層を被着させ、しかる後、シアン系の電解金めっき液中に浸漬し、ニッケルめっき層表面に金めっき層を被着させることによって行なわれる。
【００２６】
また更に前記基体１の凹部１ａ内表面には支持体８が取着されており、該支持体８の上面には前記配線層２の一部が導出され、配線層２の導出部が形成されている支持体８の上面に水晶振動子５が導電性接着剤等の固定材９を介して接着固定される。
【００２７】
前記支持体８はゴム粒子を添加したエポキシ樹脂等の弾性率が２．４ＧＰａ以下のもので形成されており、支持体８の弾性率が２．４ＧＰａ以下で、変形し易いことから、水晶振動子５の温度補償を行なう半導体素子６が作動時に熱を発生し、その熱が基体１と水晶振動子５に繰り返し作用して基体１と水晶振動子５との間に両者の熱膨張係数差に起因する熱応力が繰り返し発生したとしても、その熱応力は支持体８を適度に変形させることによって吸収され、基体１や水晶振動子５、支持体８、固定材９等に機械的な破壊が招来することはなく、その結果、基体１に水晶振動子５を長期間にわたり確実、強固に支持固定することが可能となり、水晶デバイス７の長期信頼性を高いものとなすことができる。
【００２８】
なお、前記支持体８はその弾性率が２．４ＧＰａを超えると水晶振動子５の温度補償を行なう半導体素子６の発した熱が基体１と水晶振動子５の両者に繰り返し作用した際、基体１と水晶振動子５との両者の熱膨張係数差に起因する熱応力が支持体８に繰り返し作用して支持体８に機械的な破壊を招来し、水晶振動子５の固定が破れて水晶デバイス７の信頼性が大きく低下してしまう。従って、前記支持体８はその弾性率が２．４ＧＰａ以下のものに特定される。
【００２９】
また前記弾性率が２．４ＧＰａ以下の支持体８としては、アクリルゴム、イソプレンゴム等のゴム粒子を添加したエポキシ樹脂に対して、銀粉末等の導電性粉末を１５乃至６０重量％の割合で添加したものが好適に使用される。
【００３０】
更に前記エポキシ樹脂としては、（オルソ）クレゾールノボラック型、フェノールノボラック型、ナフタレン系アラルキル型、ポリサルファイド変性型等のエポキシ樹脂、特に未硬化時に半固体状（粘度が３０００Ｐ（ポアズ）以上、室温）のものが好適に使用される。この場合、エポキシ樹脂へのゴム粒子の添加量を増加させることにより支持体８の弾性率を低下させることができ、エポキシ樹脂の状態（構造、架橋度、重合度、硬化剤の種類等）に応じて適宜ゴム粒子の添加量を制御することにより支持体８の弾性率を２．４ＧＰａ以下とすることができる。またエポキシ樹脂へのゴム粒子の添加量が５０重量％を超えると、支持体８の保形性が大きく低下し、この支持体８上に水晶振動子５を、固定材９を介して強固に接着固定することが困難となる傾向にある。従って、エポキシ樹脂中にゴム粒子を添加する場合、その添加量は、支持体８の弾性率を２．４ＧＰａ以下とする範囲で、５０重量％以下としておくことが好ましい。
【００３１】
前記支持体８は、その弾性率が１ＧＰａ未満になると、変形し易くなりすぎるため水晶振動子５を基体１上に支持固定しておくことが困難となる傾向がある。従って、前記支持体８はその弾性率を、２．４ＧＰａ以下の範囲で、１ＧＰａ以上としておくことが好ましい。
【００３２】
また、前記弾性率が２．４ＧＰａ以下の支持体８は、上述のエポキシ樹脂組成物に限らず、シリコーン樹脂等の低弾性率の熱硬化性樹脂にシリカ等のフィラー成分を添加した樹脂組成物に導電性粉末を添加することにより形成してもよい。
【００３３】
前記水晶振動子５が搭載されている基体１は、その上面に蓋体３が取着され、これによって基体１と蓋体３とから成る容器４内部に水晶振動子５が気密に収容され、水晶デバイス７となる。
【００３４】
前記蓋体３は、鉄−ニッケル−コバルト合金、鉄−ニッケル合金等の金属材料や、酸化アルミニウム質焼結体等のセラミック材料により形成され、例えば、鉄−ニッケル−コバルト合金のインゴット（塊）に圧延加工、打ち抜き加工等の周知の金属加工を施すことによって形成される。
【００３５】
更に前記蓋体３の基体１への取着は、ロウ材、ガラス、有機樹脂接着剤等の接合材を介して行う方法や、シーム溶接等の溶接法により行うことができ、例えば、蓋体３をシーム溶接にて取着する場合は通常、基体１上面の凹部１ａ周囲に枠状のロウ付け用メタライズ層１２を配線層２と同様の方法で被着させておくとともに、該ロウ付け用メタライズ層１２に金属枠体１３を銀ロウ等のロウ材を介してロウ付けし、しかる後、前記金属枠体１３に金属製の蓋体３を載置させるとともに蓋体３の外縁部をシーム溶接することによって行われる。この場合、金属枠体１３は、その上面と側面との間の角部に曲率半径が５〜３０μｍの丸みを形成しておくと金属枠体１３の上面側にバリが形成されることがなく、この金属枠体１３の上面に蓋体３をシーム溶接する際に両者を信頼性高く気密に、かつ強固に接合させることができる。従って、前記金属枠体１３はその上面と側面との間の角部を曲率半径が５〜３０μｍの丸みをもたせるようにしておくことが好ましい。
【００３６】
また更に、前記金属枠体１３は、その下面と側面との間の角部に曲率半径が４０〜８０μｍの丸みを形成しておくと、該金属枠体１３をロウ付け用メタライズ層１２にロウ材を介して接合する際、ロウ付け用メタライズ層１２と金属枠体１３の下面側角部との間に空間が形成されるとともに該空間にロウ材の大きな溜まりが形成されて金属枠体１３のロウ付け用メタライズ層１２への接合が強固となる。従って、前記金属枠体１３をロウ付け用メタライズ層１２にロウ材を介して強固に接合させるには金属枠体１３の下面と側面との間の角部に曲率半径が４０〜８０μｍの丸みを形成しておくことが好ましい。
【００３７】
また一方、前記基体１の下面に設けた凹部１ｂには水晶振動子５の温度補償を行なうための半導体素子６が収容固定されており、該半導体素子６によって水晶振動子５の振動周波数が温度変化によって変動するのを制御し、常に一定とする作用をなす。
【００３８】
前記半導体素子６はガラス、樹脂、ロウ材等の接着材を介して基体１の下面に設けた凹部１ｂの底面に接着固定され、半導体素子６の各電極はボンディングワイヤ等の導電性接続部材１０を介して基体１の凹部１ｂに露出する配線層２に電気的に接続されている。
【００３９】
また前記基体１の凹部１ｂ内に収容されている半導体素子６は凹部１ｂ内に充填させた封止樹脂１１によって気密に封止されている。
【００４０】
なお、前記半導体素子６の封止は封止樹脂１１で行なうものに限定されるものではなく、基体１の下面に蓋体を、凹部１ｂを塞ぐように取着させることによって行なってもよい。
【００４１】
かくして上述の水晶デバイス７によれば、配線層２を外部電気回路に接続し、水晶振動子５の電極に所定の電圧を印加させることによって水晶振動子５が所定の振動数で振動するとともに、半導体素子６により水晶振動子５の温度補償が行なわれ、コンピュータ等の情報処理装置や携帯電話等の電子装置において時間および周波数の高精度の基準源として使用される。
【００４２】
なお、本発明は上述の実施例に限定されるものではなく、本発明の要旨を逸脱しない範囲であれば種々の変更は可能であり、例えば、図２に示すように、配線層２の一部に突起１４を形成しておくと、この突起１４がスペーサーとなって配線層２と水晶振動子５との間に一定のスペースが確保され、このスペースに十分な固定材９が入り込んで水晶振動子５を配線層２に極めて強固に接着固定することができる。
【００４３】
また上述の水晶デバイス７では基体１上面に凹部１ａを設け、該凹部１ａ内に水晶振動子５を収容するようになしたが、これを図３に示す如く、平坦な基体１上に水晶振動子５を搭載固定し、該固定された水晶振動子５を椀状の蓋体３で気密に封止するようになした水晶デバイス７にも適用し得る。
【００４４】
【発明の効果】
本発明の水晶デバイスによれば、基体を１０乃至６８ｍｏｌ％のＢａＯ、９乃至５０ｍｏｌ％のＳｎＯ₂、１３乃至７２ｍｏｌ％のＢ₂Ｏ₃から成る酸化物焼結体で形成し、かかる酸化物焼結体の焼成温度が約８００〜１２００℃と低いことから、基体と同時焼成により形成される配線層を比電気抵抗が２．５μΩ・ｃｍ（２０℃）以下と低い銅や銀、金で形成することができ、その結果、配線層に水晶振動子の基準信号や半導体素子の駆動信号等を伝搬させた場合、基準信号や駆動信号に大きな減衰を生じることはなく、基準信号や駆動信号を外部電気回路や水晶振動子と半導体素子との間に正確、かつ確実に伝搬させることが可能となる。
【００４５】
また本発明の水晶デバイスによれば、基体の搭載部の配線層上に、ゴム粒子および導電性粉末を添加したエポキシ樹脂から成る弾性率が２．４ＧＰａ以下であって、基体と水晶振動子との間に発生する熱応力によって変形する導電性の支持体を被着させるとともに、該支持体に水晶振動子を導電性の固定材で接着固定するようにしたことから、水晶振動子の温度補償を行なう半導体素子が作動時に熱を発生し、その熱が基体と水晶振動子に繰り返し作用して基体と水晶振動子との間に両者の熱膨張係数差に起因する熱応力が繰り返し発生したとしても、その熱応力は支持体を適度に変形させることによって吸収され、水晶振動子の基体に対する固定が破れることはなく、その結果、基体に水晶振動子を長期間にわたり確実、強固に固定することが可能となり、水晶デバイスの長期信頼性を高いものとなすことができる。
【図面の簡単な説明】
【図１】本発明の水晶デバイスの一実施例を示す断面図である。
【図２】本発明の水晶デバイスの他の実施例を示す要部断面図である。
【図３】本発明の水晶デバイスの他の実施例を示す断面図である。
【符号の説明】
１・・・・・基体
１ａ・・・・凹部
１ｂ・・・・凹部
２・・・・・配線層
３・・・・・蓋体
４・・・・・容器
５・・・・・水晶振動子
６・・・・・半導体素子
７・・・・・水晶デバイス
８・・・・・支持体
９・・・・・固定材
１０・・・・導電性接続部材
１１・・・・封止樹脂
１２・・・・ロウ付け用メタライズ層
１３・・・・金属枠体
１４・・・・突起[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a temperature-compensated crystal device used as an accurate time and frequency reference source in an information processing apparatus such as a computer and an electronic apparatus such as a mobile phone.
[0002]
[Prior art]
A temperature-compensated crystal device used as an accurate time and frequency reference source in an information processing apparatus such as a computer or an electronic apparatus such as a mobile phone generally has a voltage application electrode on a rectangular plate-shaped crystal substrate. The formed crystal resonator and the semiconductor element for performing temperature compensation of the crystal resonator are hermetically housed in a crystal resonator housing package.
[0003]
The quartz crystal housing package is generally made of an electrically insulating material such as an aluminum oxide sintered body, and has a concave portion for forming a space for accommodating the quartz crystal in the central portion of the upper surface, and a semiconductor in the central portion of the lower surface. A base having a wiring layer made of a metal material such as tungsten, molybdenum, or the like, and having a wiring layer made of a refractory metal such as tungsten and molybdenum, each having a recess serving as a space for accommodating an element, and extending from the surface of each recess to the outer surface; -It is comprised from metal materials, such as a cobalt alloy and an iron-nickel alloy, or the cover body which consists of ceramic materials, such as an aluminum oxide sintered body.
[0004]
Then, the quartz resonator is adhered and fixed in the recess and the wiring layer by attaching the electrode of the crystal resonator to the inner surface of the recess on the upper surface of the substrate and the surrounding substrate surface via a fixing material. In addition, the semiconductor element is accommodated in the recess in the lower surface of the base and the electrodes of the semiconductor element are electrically connected to the wiring layer. Thereafter, the lid is bonded to the upper surface of the base with an adhesive. The quartz resonator is hermetically accommodated inside a container composed of a base and a lid, which is attached by a joining means such as seam welding, and the semiconductor element housed in a recess on the bottom of the base is sealed with a lid or a sealing resin. By stopping, the crystal device as a product is completed.
[0005]
In general, as a fixing material for attaching a crystal resonator, a conductive adhesive made by mixing an organic resin such as an epoxy resin and a conductive powder such as silver powder as a main material is used. Yes.
[0006]
Further, when the lid is attached to the base by seam welding, a frame-like brazing metallization layer is usually formed around the recess of the base in advance, and a metal frame is brazed to the metallization layer. A method of seam welding the lid to the frame is used.
[0007]
Further, the mounting of the crystal device on the external electric circuit board is performed by connecting the wiring layer led to the outer surface of the base to the wiring conductor of the external electric circuit board through a conductive connecting material such as solder, The crystal resonator is electrically connected to the external electric circuit via the wiring layer, and vibrates at a predetermined frequency according to a voltage applied from the external electric circuit, and supplies a reference signal to the external electric circuit.
[0008]
[Problems to be solved by the invention]
However, in the conventional quartz device, the wiring layer formed on the base is formed of a refractory metal material such as tungsten, molybdenum, or manganese, and the tungsten or the like has a specific electric resistance of 5.4 μΩ · cm (20 When the reference signal of the crystal resonator or the drive signal of the semiconductor element is propagated to the wiring layer, the reference signal or the drive signal is greatly attenuated, and the reference signal or the drive signal is transmitted to the external electric circuit or the crystal. There has been a drawback that it cannot be accurately and reliably propagated between the vibrator and the semiconductor element.
[0009]
The present invention has been devised in view of the above-described drawbacks, and an object of the present invention is to effectively perform temperature compensation of a crystal resonator by a semiconductor element mounted on a substrate, and to transmit a reference signal of the crystal resonator to an external electric signal. It is an object of the present invention to provide a quartz crystal device that can accurately and reliably supply a circuit.
[0010]
[Means for Solving the Problems]
The present invention provides a crystal device comprising a substrate having a crystal resonator mounting portion on the upper surface, a wiring layer extending from the mounting portion to the outer surface, and a crystal resonator mounted on the mounting portion. The substrate is an oxide sintered body composed of 10 to 68 mol% BaO, 9 to 50 mol% SnO ₂ , and 13 to 72 mol% B ₂ O ₃ , and the wiring layer is 2.5 μΩ · cm or less. It is formed of a metal material having specific electrical resistance, and is composed of an epoxy resin to which rubber particles and conductive powder are added on the wiring layer of the mounting portion, and has an elastic modulus of 2.4 GPa or less , A conductive support that is deformed by a thermal stress generated between a base and the crystal unit is formed, and the crystal unit is bonded and fixed to the support via a conductive fixing material. That It is an butterfly.
[0012]
According to the quartz crystal device of the present invention, the base is formed of an oxide sintered body composed of 10 to 68 mol% BaO, 9 to 50 mol% SnO ₂ , and 13 to 72 mol% B ₂ O _3. Since the firing temperature of the bonded body is as low as about 800 to 1200 ° C., a wiring layer formed by simultaneous firing with the substrate is formed of copper, silver, or gold having a low specific electrical resistance of 2.5 μΩ · cm (20 ° C.) or less. As a result, when the reference signal of the crystal resonator or the drive signal of the semiconductor element is propagated to the wiring layer, the reference signal or the drive signal is not greatly attenuated. It is possible to propagate accurately and reliably between the external electric circuit or the crystal resonator and the semiconductor element.
[0013]
Further, according to the crystal device of the present invention, the elastic modulus made of epoxy resin added with rubber particles and conductive powder on the wiring layer of the mounting portion of the base is 2.4 GPa or less , and the base, the crystal resonator, Since a conductive support that is deformed by the thermal stress generated during the process is attached and the crystal unit is bonded and fixed to the support with a conductive fixing material, temperature compensation of the crystal unit When the semiconductor element that performs the operation generates heat, the heat repeatedly acts on the base and the crystal unit, and thermal stress caused by the difference in thermal expansion coefficient between the base and the crystal unit is repeatedly generated. However, the thermal stress is absorbed by appropriately deforming the support, and the fixation of the crystal unit to the base is not broken. As a result, the crystal unit is securely and firmly fixed to the base for a long period of time. Becomes possible, it can be made as high long-term reliability crystal devices.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the crystal device of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view showing an embodiment of a quartz crystal device according to the present invention. In FIG. 1, 1 is a substrate, 2 is a wiring layer, and 3 is a lid. A crystal resonator 5 is hermetically accommodated in a container 4 formed by the base body 1 and the lid 3, and a semiconductor device 6 is mounted on the lower surface of the base body 1 to form a crystal device 7.
[0015]
The substrate 1 is formed of an oxide sintered body made of 10 to 68 mol% BaO, 9 to 50 mol% SnO ₂ , and 13 to 72 mol% B ₂ O _3. The crystal resonator 5 is accommodated in the concave portion 1a on the upper surface, and the semiconductor element 6 for performing temperature compensation of the crystal resonator 5 is disposed in the concave portion 1b on the lower surface. It is bonded and fixed via an adhesive material and mounted and accommodated.
[0016]
Further, in the substrate 1, the wiring layer 2 is led out from the surface of the upper and lower recesses 1a, 1b to the outer surface, and the electrode of the crystal unit 5 is exposed at the portion exposed on the surface of the recess 1a on the upper surface side of the substrate 1 of the wiring layer 2. Is bonded and fixed via a fixing material 9 such as a conductive adhesive, and the electrode of the semiconductor element 6 is connected to a portion exposed to the concave portion 1b on the lower surface side of the substrate 1 via a conductive connecting member 10 such as a bonding wire. The
[0017]
The base body 1 made of the above oxide sintered body is, for example, a slurry obtained by adding a binder mainly composed of an acrylic resin, a dispersant, a plasticizer, and an organic solvent to raw powders such as BaO, SnO ₂ , and B ₂ O _3. The slurry is made into a green sheet (raw sheet) by adopting a doctor blade method or a calender roll method, and then, the green sheet is appropriately punched and laminated in a plurality of layers, It is manufactured by firing at a temperature of 800 to 1200 ° C.
[0018]
Since the firing temperature of the substrate 1 is as low as about 800 to 1200 ° C., the wiring layer 2 formed by simultaneous firing with the substrate 1 has a low specific electrical resistance of 2.5 μΩ · cm (20 ° C.) or less, such as copper or silver. As a result, when the reference signal of the crystal resonator 5 and the drive signal of the semiconductor element 6 are propagated to the wiring layer 2, the reference signal and the drive signal are not greatly attenuated. The reference signal and the drive signal can be accurately and reliably propagated between the external electric circuit or the crystal resonator 5 and the semiconductor element 6.
[0019]
In the oxide sintered body, when BaO is less than 10 mol%, the dielectric loss increases, causing an attenuation or delay in the electric signal propagating through the wiring layer 2, and when it exceeds 68 mol%, the base 1 The mechanical strength of the material is greatly reduced. Accordingly, the amount of BaO constituting the oxide sintered body is specified to be 10 to 68 mol%.
[0020]
Further, when the oxide sintered body has SnO ₂ of less than 9 mol%, the sinterability is lowered and the mechanical strength becomes insufficient, and when it exceeds 50 mol%, the dielectric loss increases and propagates through the wiring layer 2. Electrical signals will be attenuated and delayed. Therefore, the amount of SnO ₂ constituting the oxide sintered body is specified to be 9 to 50 mol%.
[0021]
Furthermore, if the oxide sintered body has a B ₂ O ₃ content of less than 13 mol%, the firing temperature becomes high, making it difficult to fire simultaneously with the wiring layer 2 made of a metal material such as copper. If it exceeds, the chemical resistance of the oxide sintered body will be lowered, and the reliability as a crystal device will be low. Therefore, the amount of B ₂ O ₃ constituting the oxide sintered body is specified to be 13 to 72 mol%.
[0022]
Further, the wiring layer 2 formed on the base body 1 has an action of electrically connecting the crystal resonator 5 and the semiconductor element 6 accommodated in the recesses 1a and 1b and the wiring conductor of the external electric circuit board, For example, if it is made of a metal material having a specific electric resistance of 2.5 μΩ · cm (20 ° C.) or less, such as gold, silver, copper, etc., and made of copper, an appropriate organic solvent or organic binder for copper powder It is formed by printing and applying a metal paste obtained by adding and mixing them in a predetermined pattern on the surface of the green sheet to be the substrate 1 by a screen printing method or the like.
[0023]
If the exposed surface of the wiring layer 2 is covered with a plating layer (not shown) made of a metal having good corrosion resistance such as nickel and gold and good wettability with the brazing material, the wiring layer 2 is subject to oxidative corrosion. In addition to being able to prevent it well, it is possible to improve the wettability of the brazing material such as solder to the wiring layer 2, and the connection of the wiring layer 2 to the wiring conductor of the external electric circuit board is made easier and more reliable. Can be. Therefore, the wiring layer 2 has an exposed surface of a plating layer such as nickel or gold, for example, a nickel or nickel alloy plating layer having a thickness of 1 μm to 10 μm and a gold plating layer having a thickness of 0.1 to 3 μm. It is preferable to coat with.
[0024]
When the surface of the wiring layer 2 is covered with a plating layer such as nickel or gold, the arithmetic average roughness (Ra) of the outermost surface is 1.5 μm or less and the root mean square roughness (Rms) is 1.8 μm or less. If the reflectance of the light on the outermost surface is 40% or more and the electrode of the crystal unit 5 is fixed to the wiring layer 2 via the fixing material 9, and the electrode of the semiconductor element 6 is bonded to the wiring layer 2 When the electrical connection is made via the conductive connection member 10 such as a wire, the operation such as positioning becomes easy. Therefore, when the surface of the wiring layer 2 is covered with a plating layer such as nickel or gold, the arithmetic average roughness (Ra) of the outermost surface is 1.5 μm or less and the root mean square roughness (Rms) is 1.8 μm. The following is preferable.
[0025]
Further, the arithmetic average roughness (Ra) of the outermost surface of the plating layer made of nickel, gold, or the like covering the surface of the wiring layer 2 is 1.5 μm or less, and the root mean square roughness (Rms) is 1.8 μm or less. In this case, the wiring layer 2 is immersed in an electrolytic nickel plating solution in which a brightening agent such as a sulfur compound is added to a well-known Watt bath so that the nickel plating layer is deposited on the surface of the wiring layer 2, and then the cyan electrolysis is performed. It is carried out by dipping in a gold plating solution and depositing a gold plating layer on the surface of the nickel plating layer.
[0026]
Further, a support 8 is attached to the inner surface of the recess 1 a of the base 1, and a part of the wiring layer 2 is led out on the upper surface of the support 8 to form a lead-out portion of the wiring layer 2. The crystal unit 5 is bonded and fixed to the upper surface of the support 8 through a fixing material 9 such as a conductive adhesive.
[0027]
Since the support 8 is formed of an epoxy resin or the like with rubber particles added having an elastic modulus of 2.4 GPa or less, and the support 8 has an elastic modulus of 2.4 GPa or less and is easily deformed, The semiconductor element 6 that compensates the temperature of the element 5 generates heat during operation, and the heat repeatedly acts on the base 1 and the crystal unit 5 to cause a difference in thermal expansion coefficient between the base 1 and the crystal unit 5. Even if the thermal stress caused by the above is repeatedly generated, the thermal stress is absorbed by appropriately deforming the support 8, and mechanical damage is caused to the base 1, the crystal unit 5, the support 8, the fixing material 9 and the like. As a result, the quartz resonator 5 can be securely supported and fixed to the substrate 1 for a long period of time, and the long-term reliability of the quartz device 7 can be improved.
[0028]
When the elastic modulus of the support 8 exceeds 2.4 GPa, when the heat generated by the semiconductor element 6 that compensates the temperature of the crystal resonator 5 repeatedly acts on both the substrate 1 and the crystal resonator 5, the substrate 8 The thermal stress caused by the difference in thermal expansion coefficient between the first and second quartz resonators 5 is repeatedly applied to the support 8 to cause mechanical destruction of the support 8, and the quartz resonator 5 is fixed and broken. The reliability of the device 7 is greatly reduced. Therefore, the support 8 is specified to have an elastic modulus of 2.4 GPa or less.
[0029]
Further, as the support 8 having an elastic modulus of 2.4 GPa or less, a conductive powder such as silver powder is contained in an amount of 15 to 60% by weight with respect to an epoxy resin to which rubber particles such as acrylic rubber and isoprene rubber are added. Those added are preferably used.
[0030]
Furthermore, as the epoxy resin, epoxy resins such as (ortho) cresol novolak type, phenol novolak type, naphthalene aralkyl type, polysulfide modified type, etc., particularly semi-solid when uncured (viscosity is 3000 P (poise) or more, room temperature) Those are preferably used. In this case, the elastic modulus of the support 8 can be reduced by increasing the amount of rubber particles added to the epoxy resin, and the epoxy resin state (structure, degree of crosslinking, degree of polymerization, type of curing agent, etc.) can be reduced. Accordingly, the elastic modulus of the support 8 can be adjusted to 2.4 GPa or less by appropriately controlling the amount of rubber particles added. When the amount of the rubber particles added to the epoxy resin exceeds 50% by weight, the shape retention of the support 8 is greatly reduced, and the crystal unit 5 is firmly fixed on the support 8 via the fixing material 9. It tends to be difficult to bond and fix. Therefore, when rubber particles are added to the epoxy resin, the addition amount is preferably 50% by weight or less within a range where the elastic modulus of the support 8 is 2.4 GPa or less.
[0031]
When the elastic modulus of the support 8 is less than 1 GPa, the support 8 is likely to be deformed too much, so that it is difficult to support and fix the crystal unit 5 on the base 1. Therefore, the support 8 preferably has an elastic modulus of 1 GPa or more in the range of 2.4 GPa or less.
[0032]
The support 8 having an elastic modulus of 2.4 GPa or less is not limited to the above-described epoxy resin composition, and is a resin composition in which a filler component such as silica is added to a thermosetting resin having a low elastic modulus such as a silicone resin. You may form by adding electroconductive powder to.
[0033]
The base body 1 on which the crystal unit 5 is mounted has a lid 3 attached to the upper surface thereof, whereby the crystal unit 5 is hermetically accommodated inside the container 4 composed of the base unit 1 and the lid body 3. The crystal device 7 is obtained.
[0034]
The lid 3 is formed of a metal material such as an iron-nickel-cobalt alloy or an iron-nickel alloy, or a ceramic material such as an aluminum oxide sintered body. For example, an iron-nickel-cobalt alloy ingot Is formed by performing known metal processing such as rolling and punching.
[0035]
Further, the lid 3 can be attached to the base body 1 by a method using a bonding material such as a brazing material, glass, or an organic resin adhesive, or by a welding method such as seam welding. When attaching 3 by seam welding, a frame-like brazing metallization layer 12 is usually applied around the recess 1a on the upper surface of the substrate 1 in the same manner as the wiring layer 2, and the brazing A metal frame 13 is brazed to the metallized layer 12 via a brazing material such as silver solder, and then the metal lid 3 is placed on the metal frame 13 and the outer edge of the lid 3 is seamed. This is done by welding. In this case, if the metal frame 13 is rounded with a radius of curvature of 5 to 30 μm at the corner between the upper surface and the side surface, no burr is formed on the upper surface side of the metal frame 13. When the lid 3 is seam welded to the upper surface of the metal frame 13, the two can be reliably and airtightly bonded. Therefore, it is preferable that the metal frame 13 has a round corner with a radius of curvature of 5 to 30 μm at the corner between the upper surface and the side surface.
[0036]
Furthermore, when the metal frame 13 is rounded with a radius of curvature of 40 to 80 μm at the corner between its lower surface and side surface, the metal frame 13 is brazed to the brazing metallization layer 12. When joining via the material, a space is formed between the brazing metallized layer 12 and the lower surface side corner of the metal frame 13, and a large pool of brazing material is formed in the space, and the metal frame 13 is formed. The bonding to the brazing metallization layer 12 becomes strong. Accordingly, in order to firmly bond the metal frame 13 to the brazing metallization layer 12 via the brazing material, the corner between the lower surface and the side surface of the metal frame 13 is rounded with a curvature radius of 40 to 80 μm. It is preferable to form it.
[0037]
On the other hand, a semiconductor element 6 for carrying out temperature compensation of the crystal resonator 5 is accommodated and fixed in the recess 1b provided on the lower surface of the base 1, and the vibration frequency of the crystal resonator 5 is controlled by the semiconductor element 6 at a temperature. Controls fluctuations due to changes, and always keeps constant.
[0038]
The semiconductor element 6 is bonded and fixed to the bottom surface of the recess 1b provided on the lower surface of the substrate 1 through an adhesive such as glass, resin, brazing material, etc., and each electrode of the semiconductor element 6 is a conductive connecting member 10 such as a bonding wire. And electrically connected to the wiring layer 2 exposed in the recess 1b of the base body 1.
[0039]
The semiconductor element 6 accommodated in the recess 1b of the substrate 1 is hermetically sealed with a sealing resin 11 filled in the recess 1b.
[0040]
The semiconductor element 6 is not limited to sealing with the sealing resin 11 but may be performed by attaching a lid to the lower surface of the substrate 1 so as to close the recess 1b.
[0041]
Thus, according to the crystal device 7 described above, the crystal layer 5 vibrates at a predetermined frequency by connecting the wiring layer 2 to an external electric circuit and applying a predetermined voltage to the electrode of the crystal resonator 5. The temperature of the crystal unit 5 is compensated by the semiconductor element 6 and is used as an accurate time and frequency reference source in an information processing device such as a computer and an electronic device such as a mobile phone.
[0042]
Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIG. If the protrusion 14 is formed in the portion, the protrusion 14 serves as a spacer to secure a certain space between the wiring layer 2 and the crystal resonator 5, and a sufficient fixing material 9 enters the space so that the crystal The vibrator 5 can be bonded and fixed to the wiring layer 2 very firmly.
[0043]
Further, in the above-described crystal device 7, the recess 1a is provided on the upper surface of the base 1, and the crystal resonator 5 is accommodated in the recess 1a. As shown in FIG. The present invention can also be applied to a crystal device 7 in which a child 5 is mounted and fixed, and the fixed crystal resonator 5 is hermetically sealed with a bowl-shaped lid 3.
[0044]
【The invention's effect】
According to the quartz crystal device of the present invention, the base is formed of an oxide sintered body composed of 10 to 68 mol% BaO, 9 to 50 mol% SnO ₂ , and 13 to 72 mol% B ₂ O _3. Since the firing temperature of the bonded body is as low as about 800 to 1200 ° C., a wiring layer formed by simultaneous firing with the substrate is formed of copper, silver, or gold having a low specific electrical resistance of 2.5 μΩ · cm (20 ° C.) or less. As a result, when the reference signal of the crystal resonator or the drive signal of the semiconductor element is propagated to the wiring layer, the reference signal or the drive signal is not greatly attenuated. It is possible to propagate accurately and reliably between the external electric circuit or the crystal resonator and the semiconductor element.
[0045]
Further, according to the crystal device of the present invention, the elastic modulus made of epoxy resin added with rubber particles and conductive powder on the wiring layer of the mounting portion of the base is 2.4 GPa or less , and the base, the crystal resonator, Since a conductive support that is deformed by the thermal stress generated during the process is attached and the crystal unit is bonded and fixed to the support with a conductive fixing material, temperature compensation of the crystal unit When the semiconductor element that performs the operation generates heat, the heat repeatedly acts on the base and the crystal unit, and thermal stress caused by the difference in thermal expansion coefficient between the base and the crystal unit is repeatedly generated. However, the thermal stress is absorbed by appropriately deforming the support, and the fixation of the crystal unit to the base is not broken. As a result, the crystal unit is securely and firmly fixed to the base for a long period of time. Becomes possible, it can be made as high long-term reliability crystal devices.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a quartz crystal device of the present invention.
FIG. 2 is a cross-sectional view of an essential part showing another embodiment of the quartz crystal device of the present invention.
FIG. 3 is a cross-sectional view showing another embodiment of the quartz crystal device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base | substrate 1a ... Recess 1b ... Recess 2 ... Wiring layer 3 ... Cover body 4 ... Container 5 ... Quartz vibration Child 6... Semiconductor element 7... Crystal device 8... Support 9... Fixing material 10... Conductive connection member 11. 12 ... Metallization layer for brazing 13 ... Metal frame 14 ... Projection

Claims

A quartz crystal device comprising a substrate having a quartz resonator mounting portion on an upper surface thereof, a substrate from which a wiring layer is led out from the mounting portion to an outer surface, and a crystal resonator mounted on the mounting portion;
The substrate is an oxide sintered body composed of 10 to 68 mol% BaO, 9 to 50 mol% SnO ₂ , and 13 to 72 mol% B ₂ O ₃ , and the wiring layer has a specific electric resistance of 2.5 μΩ · cm or less. And is formed of an epoxy resin to which rubber particles and conductive powder are added on the wiring layer of the mounting portion, and has an elastic modulus of 2.4 GPa or less , the base and the substrate A conductive support that is deformed by thermal stress generated between the crystal unit and the crystal unit is formed, and the crystal unit is bonded and fixed to the support unit through a conductive fixing material. Crystal device characterized by.