JP2004031704A

JP2004031704A - Vessel for piezoelectric oscillator

Info

Publication number: JP2004031704A
Application number: JP2002186865A
Authority: JP
Inventors: Yoshiaki Ito; 伊藤　吉明
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-06-26
Filing date: 2002-06-26
Publication date: 2004-01-29
Anticipated expiration: 2022-06-26
Also published as: JP3792612B2

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of vacuum sealing being difficult due to the evaporation of the glass component out of a sealing material in the process of heating a conductive bonding material in a vacuum for the bonding of a piezoelectric oscillator. <P>SOLUTION: The vessel for a piezoelectric oscillator comprises an insulating substrate 1 having a recess 1a on the upper surface for mounting a piezoelectric oscillator 3; and a plate-type cover 2 which is positioned on the insulating substrate 1 to cover the recess 1a, bonded to the insulating substrate 1 via a sealing material 10, and provided with a through-hole 6 pnenetrating from the upper surface to the lower surface. In the space created between the insulating substrate 1 and the plate-type cover 2, a piezoelectric oscillator 3 is accommodated. The sealing material 10 includes a glass component comprising 30-40 mass% of phosphorus pentoxide, 37-50 mass% of tin monoxide, 5-15 mass% of sodium oxide, 1-6 mass% of zinc oxide, 1-4 mass% of aluminum oxide, and 1-3 mass% of silicon oxide, and also includes a 16-45 mass% of a cordierite-based compound externally added to the glass component as a filler. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は圧電振動子片を収容するための圧電振動子用容器に関し、特に封止材にガラスを用いて封止を行なう圧電振動子用容器に関する。
【０００２】
【従来の技術】
従来、圧電振動子は、圧電振動子用容器内に圧電振動子片を気密に収容することによって製作されている。
このような圧電振動子片を気密に収容する圧電振動子用容器は、例えば酸化アルミニウム質焼結体等のセラミックスから成り、その上面の略中央部に圧電振動子片を搭載するための凹部を有する絶縁基体と、同じく酸化アルミニウム質焼結体等のセラミックスから成り、絶縁基体の上面に低融点ガラス等の封止材を介して接合されることにより絶縁基体との間の空間に圧電振動子片を収容する蓋体とから構成されている。
【０００３】
また、容器内部に収容される圧電振動子片が、例えば周波数特性上１．３×１０^−２Ｐａ程度の真空封止を必要とする圧電振動子片の場合、絶縁基体には、絶縁基体と蓋体との間の空間を真空に排気するための貫通孔がその上面から下面にかけて形成されている。そして、これら絶縁基体と蓋体とから成る容器の内部に圧電振動子片を導電性の接着材で接着固定し真空中で加熱処理した後、絶縁基体に形成された貫通孔を介して圧電振動子片を収容する空間を真空に排気し、しかる後、この貫通孔内に金−錫合金等のろう材から成る封止部材を充填してこの貫通孔を封止することにより、圧電振動子用容器の内部に圧電振動子片が気密に収容された圧電振動子となる。
【０００４】
なお、絶縁基体と蓋体とを封止する封止材は、通常、圧電振動子片を絶縁基体に導電性の接着材で接着固定する前に、あらかじめ絶縁基体に被着されている。また、このような封止材としては、例えば酸化鉛５０〜６５重量％、酸化硼素２〜１０重量％、酸化亜鉛１〜６重量％、フッ化鉛１０〜３０重量％、酸化ビスマス１０〜２０重量％を含むガラス成分に、フィラーとしてチタン酸鉛化合物を２６〜４５重量％添加した鉛系のガラスが使用されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、この従来の圧電振動子は、絶縁基体に蓋体を接合させる封止材として、酸化鉛５０〜６５重量％、酸化硼素２〜１０重量％、酸化亜鉛１〜６重量％、フッ化鉛１０〜３０重量％、酸化ビスマス１０〜２０重量％を含むガラス成分に、フィラーとしてチタン酸鉛化合物を２６〜４５重量％添加した鉛系ガラスが使用されていることから、圧電振動子片を導電性の接着材で接着固定した後に真空中で加熱処理する際に、あらかじめ絶縁基体に被着させた封止材中のフッ素成分が揮発し封止材のガラスが結晶化してしまい、絶縁基体と蓋体との強固な接合が困難となり、真空封止した容器内部の真空度の低下を招き、圧電振動子片のＱ値を低下させたりその表面電極を酸化腐食させてしまうという問題点を有していた。
【０００６】
また、今般携帯電話等の移動体通信機器の小型・薄型化にともない圧電振動子に関しても小型・薄型化の更なる要求があり、従来の絶縁基体の上面から下面にかけて形成された貫通孔で容器内の空間を真空に排気する容器構造では、実装後の機械的強度が低下し移動体通信機器に加わる機械的応力や衝撃力に耐えることができず、絶縁基体もしくは封止材にクラックを招来し、真空封止した容器内部の真空度の低下を招き、圧電振動子片のＱ値を低下させたりその表面電極を酸化腐食させてしまうという可能性も有していた。
【０００７】
さらに、近年地球環境保護運動の高まりの中で、酸化鉛は環境負荷物質に指定されており、例えば酸化鉛を含む電子装置が屋外に廃棄・放置され風雨に曝された場合、環境中に鉛が溶けだし環境を汚染する可能性があり、人体に対して有害である酸化鉛を用いない封止材の開発が要求されるようになってきた。
【０００８】
本発明は上記問題点に鑑み案出されたもので、その目的は、絶縁基体と蓋体とから成る容器の内部に圧電振動子片を真空中で気密に封止し、その特性に劣化を招来することがなく、圧電振動子を長期間にわたり正常かつ安定に作動させることができる圧電振動子用容器を提供することにある。
【０００９】
【課題を解決するための手段】
本発明の圧電振動子用容器は、上面に圧電振動子片を搭載するための凹部を有する絶縁基体と、この絶縁基体の上面に凹部を覆うように封止材を介して接合され、絶縁基体との間の空間に圧電振動子片を収容する、上面から下面にかけて貫通孔が設けられた略平板状の蓋体とから成る圧電振動子用容器であって、封止材が五酸化燐３０〜４０質量％、一酸化錫３７〜５０質量％、酸化ナトリウム５〜１５質量％、酸化亜鉛１〜６質量％、酸化アルミニウム１〜４質量％および酸化珪素１〜３質量％を含むガラス成分にフィラーとしてコージェライト系化合物を外添加で１６〜４５質量％添加したものから成ることを特徴とするものである。
【００１０】
本発明の圧電振動子用容器によれば、絶縁基体と蓋体とを封止する封止材が五酸化燐３０〜４０質量％、一酸化錫３７〜５０質量％、酸化ナトリウム５〜１５質量％、酸化亜鉛１〜６質量％、酸化アルミニウム１〜４質量％および酸化珪素１〜３質量％を含むガラス成分にフィラーとしてコージェライト系化合物を外添加で１６〜４５質量％添加したものから成ることから、圧電振動子の特性を向上させるために圧電振動子片を絶縁基体に導電性の接着材で接着固定した後に真空中で加熱処理しても、絶縁基体側にあらかじめ被着させた封止材のガラス成分が揮発してガラスの結晶化が進むことはなく、絶縁基体と蓋体との極めて強固な封着が可能となり、その結果、容器内部の圧電振動子片にそのＱ値を低下させたりその表面電極を酸化腐食させてしまうという悪影響を与えるような容器内部の真空度の低下を抑えることが可能になり、圧電振動子をその特性に劣化招来することなく気密に封止し、長期間にわたり安定に作動させることが可能となる。
【００１１】
また、本発明の圧電振動子用容器によれば、上面に圧電振動子片を搭載する凹部を有する絶縁基体と、絶縁基体の上面に凹部を覆うように封止材を介して接合され、絶縁基体との間の空間に圧電振動子片を収容するとともに上面から下面にかけて貫通孔が設けられた略平板状の蓋体とから成ることから、携帯電話等の移動体通信機器の小型・薄型化にともない圧電振動子を薄型化したとしても、ボード実装後に応力の集中する絶縁基体側に真空排気用の貫通孔が存在しないため、容器内部の圧電振動子片にそのＱ値を低下させたりその表面電極を酸化腐食させてしまうという悪影響を与えるような容器内部の真空度の低下を抑えることが可能になり、その結果、圧電振動子をその特性に劣化招来することなく気密に封止し、長期間にわたり安定に作動させることが可能となる。
【００１２】
さらに、本発明の圧電振動子用容器によれば、絶縁基体と蓋体とを接合させる封止材は、酸化鉛を含まないガラスで構成したことから、人体に害を与えたり地球環境に負荷を与えることはない。
【００１３】
【発明の実施の形態】
次に、本発明の圧電振動子用容器を添付の図面に基づいて詳細に説明する。
図１は本発明の圧電振動子用容器およびこれを用いた圧電振動子の実施の形態の一例を示す断面図であり、この図において１は絶縁基体、２は蓋体、３は圧電振動子片である。そして、絶縁基体１と蓋体２とから成る容器内部に圧電振動子片３を気密に封止することによって圧電振動子が形成される。
【００１４】
圧電振動子用容器を構成する絶縁基体１は、酸化アルミニウム質焼結体や窒化アルミニウム質焼結体・炭化珪素質焼結体・窒化珪素質焼結体・ムライト質焼結体・ガラスセラミックス焼結体等の電気絶縁材料から成り、その上面の略中央部に圧電振動子片３を搭載するための凹部１ａが形成された略四角平板状であり、凹部１ａの底面には圧電振動子片３が接着材５を介して接着固定される。
【００１５】
なお、絶縁基体１は、その幅が２〜５ｍｍ、長さが５〜１０ｍｍ、厚みが０．３〜０．６ｍｍであり、凹部１ａは、その幅が１〜４ｍｍ、長さが４〜９ｍｍ、深さが０．２〜０．５ｍｍである。そして圧電振動子片３の小型・薄型化の要求に伴い、その小型化・薄型化がますます進んでいる。
【００１６】
このような絶縁基体１は、例えば絶縁基体１が酸化アルミニウム質焼結体から成る場合であれば、酸化アルミニウム・酸化珪素・酸化マグネシウム・酸化カルシウム等の原料粉末に適当な有機バインダ・溶剤・可塑剤・分散剤等を添加混合して泥漿物を作り、この泥漿物を従来周知のドクターブレード法やカレンダーロール法等のシート成形法を採用しシート状に成形してセラミックグリーンシート（セラミック生シート）を得、しかる後、それらセラミック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１６００℃の高温で焼成することによって製作される。
【００１７】
また、絶縁基体１の凹部１ａの底面から下面にかけて複数個のメタライズ配線層４が被着形成されている。このメタライズ配線層４の凹部１ａの底面に位置する部位には圧電振動子片３の各電極が接着材５を介して電気的に接続され、また絶縁基体１の下面に導出された部位には外部電気回路の配線導体（図示せず）が金−錫合金等のロウ材を介して取着される。
【００１８】
メタライズ配線層４はタングステンやモリブデン・マンガン等の高融点金属粉末に適当な有機溶剤・溶媒・可塑剤等を添加混合して得た金属ペーストを従来周知のスクリーン印刷法等の厚膜手法を採用して絶縁基体１となるセラミックグリーンシートにあらかじめ印刷塗布しておき、これをセラミックグリーンシートと同時に焼成することによって絶縁基体１の凹部１ａの底面から下面にかけて所定パターンに被着形成される。
【００１９】
なお、メタライズ配線層４は、その露出する表面にニッケル・金等の良導電性で耐蝕性およびろう材との濡れ性が良好な金属をめっき法により１〜２０μｍの厚みに被着させておくと、メタライズ配線層４の酸化腐蝕を有効に防止することができるとともにメタライズ配線層４と圧電振動子片３との接着材５を介しての接続およびメタライズ配線層４と外部電極とのろう付けを極めて強固となすことができる。
【００２０】
接着材５は、例えば銀−ポリイミド樹脂等から成り、絶縁基体１の凹部１ａの底面に露出するメタライズ配線層４の一端に接着材５を介して圧電振動子片３を載置させ、しかる後、接着材５を約３００℃の温度に加熱して熱硬化処理を施し、熱硬化させることによって圧電振動子片３を絶縁基体１に接着固定させる。この際、接着材５を真空中で熱処理することによって、樹脂性の接着材５の耐熱性を向上させることができ、圧電振動子が外部回路基板への実装時に受ける熱履歴による圧電振動子片３の周波数特性の変動を極小に抑えることが可能となる。
【００２１】
また、絶縁基体１には、蓋体２が封止材１０を介して接合される。蓋体２は、容器内部に圧電振動子片３を気密に収容する機能を有し、例えば酸化アルミニウム質焼結体等のセラミックスから形成されている。そして、蓋体２にはその略中央部に底面から下面にかけて貫通孔６が形成されている。
【００２２】
貫通孔６は、絶縁基体１と蓋体２とから成る容器の内部に圧電振動子片３を収容した後、この圧電振動子片３を収容する空間を真空に排気するための排気孔として機能する。この貫通孔６は、蓋体２の上面側の第１の孔６ａと、この第１の孔６ａよりも開口が小さな下面側の第２の孔６ｂとから成るとともに、第１の孔６ａの第２の孔６ｂ側の開口の周辺、具体的には第１の孔６ａと第２の孔６ｂとの間に形成された段部の表面に後述する封止用金属部材７を取着するための金属層８が被着されている。
【００２３】
なお、第１の孔６ａおよび第２の孔６ｂは、好ましくは開口が円形の孔であり、第１の孔６ａが０．５ｍｍ〜０．９ｍｍの直径を、第２の孔６ｂが第１の孔６ａの直径より０．１ｍｍ〜０．４ｍｍ小さな直径を有している。ただし、第１の孔６ａおよび第２の孔６ｂは、必ずしも開口が円形である必要はなく、開口が三角形や四角形あるいはその他の形状であってもよい。また、第１の孔６ａの第２の孔６ｂ側の開口部の周辺に被着させた金属層８は、蓋体２の上面に達しない範囲であれば、その一部が第１の孔６ａ内に多少入り込んでいても差し支えない。
【００２４】
そして、貫通孔６の金属層８には、絶縁基体１と蓋体２との間の空間に圧電振動子片３を収容し、この圧電振動子片３を収容する空間を真空に排気した後に、封止用金属部材７がろう材９を介して取着される。これにより貫通孔６が封止され、圧電振動子用容器が気密に封止される。
【００２５】
なお、貫通孔６を封止するための封止用金属部材７が取着される金属層８は、タングシテンやモリブデン・銀・銅等の金属粉末を用いたメタライズ金属層から成り、ろう材９との塗れ性を良好なものとするためにその表面に必要に応じて図示しないニッケルや金等から成るめっき金属層を被着させている。
【００２６】
そして、金属層８は貫通孔６内で第１の孔６ａの第２の孔６ｂ側の開口の周辺に被着されていることから、封止用金属部材７を取着するろう材９は金属層８が被着された第１の孔６ａの第２の孔６ｂの開口の周辺にのみ塗れ広がるので、この金属層８に封止用金属部材７をろう材９を介して取着することによって貫通孔６を封止する際にろう材９が蓋体２の上下面に達するようなことはない。
【００２７】
また、溶融したろう材９の表面張力により封止用金属部材７は第１の孔６ａの第２の孔６ｂの開口の周辺に保持されるので、ろう材９や封止用金属部材７が蓋体２の下面から突出して圧電振動子片３の振動を妨げたり、あるいは蓋体２の上面から突出して、圧電振動子を外部回路基板に実装する際にその実装を妨げたりすることはない。
【００２８】
なお、貫通孔６は、蓋体２となるセラミックグリーンシートに貫通孔６となる孔をあらかじめ所定の大きさ・形状に穿孔しておくことによって、蓋体２の上面から下面にかけて、上面側の第１の孔６ａとこの第１の孔６ａの開口より小さな下面側の第２の孔６ｂとから成るように形成される。
【００２９】
また、金属層８は、タングステン等の金属粉末に適当な有機バインダおよび溶剤等を添加混合して得た金属ペーストを絶縁基体１となるセラミックグリーンシートとともに焼成することによって、蓋体２に形成された貫通孔６において第１の孔６ａの第２の孔６ｂ側の開口の周辺、具体的には第１の孔６ａと第２の孔６ｂとの間に形成された段部の上面に被着される。
【００３０】
貫通孔６を封止する封止用金属部材７は、例えば銅等の金属から成る球体であり、また、封止用金属部材７を金属層８に取着しているろう材９は、例えば金−錫合金等の合金から成るろう材である。
【００３１】
そして、貫通孔６の金属層８には、絶縁基体１と蓋体２との間の空間に圧電振動子片３を収容し、この圧電振動子片３を収容する空間を真空に排気した後に、封止用金属部材７がろう材９を介して取着される。これにより貫通孔６が封止され、圧電振動子用容器が気密に封止される。
【００３２】
蓋体２の絶縁基体１への封止材１０を介した接合は、例えば、まず絶縁基体１の上面外周部に封止材１０をあらかじめ被着させておき、次に圧電振動子片３を導電性の接着材５で絶縁基体１に接着固定した後に圧電振動子を接着する導電性の接着材を真空中で加熱し、さらにこの封止材１０を間に挟んで絶縁基体１の上面に蓋体２を載置し、最後にこの封止材１０を加熱して軟化溶融させた後、冷却固化することによって行われる。
【００３３】
なお、絶縁基体１の上面に外周部に封止材１０あらかじめ被着させるには、絶縁基体１の上面外周部に封止材１０となるガラスペーストをスクリーン印刷法で印刷塗布するとともに、このガラスペーストを加熱し軟化溶融させた後、冷却固化させることにより絶縁基体１の上面に封止材１０を被着させる方法が採用される。
【００３４】
また、本発明の圧電振動子用容器では、封止材１０は五酸化燐３０〜４０質量％、一酸化錫３７〜５０質量％、酸化ナトリウム５〜１５質量％、酸化亜鉛１〜６質量％、酸化アルミニウム１〜４質量％および酸化珪素１〜３質量％を含むガラス成分にフィラーとしてコージェライト系化合物を外添加で１６〜４５質量％添加したものである。そして、本発明の圧電振動子用容器においては、このことが重要である。
【００３５】
本発明の圧電振動子用容器によれば、封止材１０を五酸化燐３０〜４０質量％、一酸化錫３７〜５０質量％、酸化ナトリウム５〜１５質量％、酸化亜鉛１〜６質量％、酸化アルミニウム１〜４質量％および酸化珪素１〜３質量％を含むガラス成分にフィラーとしてコージェライト系化合物を外添加で１６〜４５質量％添加したものとしたことから、封止材１０がフッ素成分を含んでおらず、真空中で軟化点以上の温度に保持した場合でもガラス成分が揮発することはなく、圧電振動子の周波数特性を向上させるために、圧電振動子片３を導電性の接着材５で接着固定した後に真空中で加熱処理しても、絶縁基体１にあらかじめ被着させた封止ガラス中の成分が揮発することはなく、真空加熱による封止ガラスの結晶化は進行せず、蓋体２との極めて強固な封着が可能となり、容器内部の圧電振動子片３にそのＱ値を低下させたりその表面電極を酸化腐食させてしまうという悪影響を与えるような容器内部の真空度の低下を抑えることが可能になる。その結果、圧電振動子片３をその特性に劣化招来することなく気密に封止し、長期間にわたり安定に作動させることが可能となる。
【００３６】
なお、封止材１０のガラス成分は、五酸化燐の量が、３０質量％未満であるとガラスの軟化溶融温度が高くなって、低温での容器の気密封止が困難となる傾向があり、他方、４０質量％を超えるとガラスの耐薬品性が低下し、容器の気密封止の信頼性が大きく低下してしまう傾向がある。従って、五酸化燐の量は、３０〜４０質量％の範囲であることが好ましい。
【００３７】
また、一酸化錫の量が、３７質量％未満であるとガラスの軟化溶融温度が高くなって、低温での容器の気密封止が困難となる傾向があり、他方、５０質量％を超えるとガラスの耐薬品性が低下し、容器の気密封止の信頼性が大きく低下してしまう傾向がある。従って、一酸化錫の量は、３７〜５０質量％の範囲であることが好ましい。
【００３８】
また、酸化ナトリウムの量が、５質量％未満であるとガラスの軟化溶融温度が高くなって、低温での容器の気密封止が困難となる傾向があり、他方、１５質量％を超えるとガラスの耐薬品性が低下し、容器の気密封止の信頼性が大きく低下してしまう傾向がある。従って、酸化ナトリウムの量は、５〜１５重量％の範囲であることが好ましい。
【００３９】
また、酸化亜鉛が１質量％未満であるとガラスの耐薬品性が低下し、容器の気密封止の信頼性が大きく低下してしまう傾向があり、他方、６質量％を超えるとガラスの結晶化が進み低温での容器の気密封止が困難となる傾向にある。従って、酸化亜鉛の量は、１〜６質量％の範囲であることが好ましい。
【００４０】
また、酸化アルミニウムの量が、１質量％未満であるとガラスの耐湿性が低下し、封止材１０を介して容器の気密封止の信頼性が低下する傾向にあり、他方、４質量％を超えるとガラスの軟化溶融温度が高くなり、低温での容器の気密封止が困難となる傾向がある。従って、酸化アルミニウムの量は、１〜４質量％の範囲であることが好ましい。
【００４１】
また、酸化珪素の量が、１質量％未満であるとガラスの熱膨張係数が大きくなって絶縁基体１および蓋体２の熱膨張係数と大きく異なってしまい、容器の気密封止の信頼性が大きく低下する傾向にあり、他方、３質量％を超えるとガラスの軟化溶融温度が高くなり、低温での容器の気密封止が困難となる傾向がある。従って、酸化珪素の量は、１〜３質量％の範囲であることが好ましい。
【００４２】
また、コージェライト系化合物の量が、１６質量％未満であるとガラス封止材１０の強度が低下し容器の気密封止の信頼性が大きく低下する傾向があり、他方、４５質量％を超えると封止材１０の低温での流動性が低下し、容器の気密封止の信頼性が低下する傾向がある。従って、コージェライト系化合物の量は、１６〜４５質量％の範囲であることが好ましい。
【００４３】
なお、本発明の圧電振動子用容器において、ろう材９および封止材１０はいずれも酸化鉛を含有していないことから、人体に害を与えたり地球環境に負荷を与えることはない。
【００４４】
かくして本発明の圧電振動子用容器によれば、絶縁基体１のメタライズ配線層４の搭載部１ａに位置する部位に圧電振動子片３の一端を銀−ポリイミド等から成る接着材５を介して接着固定するとともに圧電振動子片３の各電極をメタライズ配線層４に電気的に接続させ、しかる後、絶縁基体１の搭載部１ａを覆うように蓋体２を封止材１０を介して接合させることにより、絶縁基体１と蓋体２との間の空間に圧電振動子片３が収容される。また、圧電振動子片３が収容された絶縁基体１と蓋体２との間の空間は、空間内部のガスが圧電振動子片３の振動を妨げないようにするために真空に排気されており、それとともに絶縁基体１に形成された貫通孔６内の金属層８に封止用金属部材７をろう材９を介して取着することにより気密に封止される。このとき、圧電振動子は圧電振動子片３を収容している容器内の空間が真空に排気されていることから高いＱを得ることができる。
【００４５】
【実施例】
効果の確認を行なうために、次の実験を行なった。なお、ここでは、主成分の五酸化燐、一酸化錫および外添加のフィラー添加量について決定した実験例を示す。
まず、各構成要素の質量％を変化させてガラスを作製した。そして、各ガラスを用いた容器の気密信頼性を評価するために、熱衝撃試験１０００サイクル後の封止容器のヘリウムガスリークテストを実施した。また、蓋体の封着強度を比較するために、容器と金体とのせん断強度を測定した。なお、評価用容器としては、絶縁基体の縦方向の寸法が５．０ｍｍ、横方向の寸法が３．２ｍｍ、高さが０．７ｍｍであり、蓋体との接合面の幅が０．５ｍｍの容器を用いた。
【００４６】
（実験１）
五酸化燐を２５〜４５質量％の間で変化させ、その他の構成要素を加えて合計が１００質量％となるように調合（小数点２桁以下を四捨五入）した。この時の実験結果を表１に示す。
【００４７】
【表１】

【００４８】
実験結果より、五酸化燐については、３０〜４０質量％の範囲で良好な気密性信頼性を示すとともに５０Ｎ（ニュートン）以上の高いせん断強度が得られることがわかった。
【００４９】
次に、一酸化錫および五酸化燐について、次の実験を行なった。
（実験２）
五酸化燐の含有量を３０〜４０質量％の範囲とし、一酸化錫の含有量を３０〜５５質量％の間で変化させ、その他の構成要素を加えて合計が１００質量％となるように調合（小数点２桁以下を四捨五入）した。結果を表２に示す。
【００５０】
【表２】

【００５１】
実験結果より、一酸化錫については、３７〜５０質量％の範囲で良好な気密性信頼性を示すとともに５０Ｎ（ニュートン）以上の高いせん断強度が得られることがわかった。
【００５２】
また、微量元素においても同種の実験を行い、ガラス封止材が五酸化燐３０〜４０質量％、一酸化錫３７〜５０質量％、酸化ナトリウム５〜１５質量％、酸化亜鉛１〜６質量％、酸化アルミニウム１〜４質量％および酸化珪素１〜３質量％を含むガラスの場合において、良好な気密性信頼性を示すとともに５０Ｎ（ニュートン）以上の高いせん断強度が得られることがわかり、本発明の効果を確認することができた。
【００５３】
（実験３）
さらに、ガラス組成を一定にし、フィラー添加量を変化させての同様の実験を行なった。評価結果を表３に示す。
【００５４】
【表３】

【００５５】
フィラーとしては、コージェライト系化合物を外添加で１６〜４５質量％添加した場合において良好な気密性信頼性が得られるとともに５０Ｎ（ニュートン）以上の高いせん断強度が得られることがわかった。
【００５６】
なお、本発明は上述の実施の形態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や改良を施すことは何ら差し支えない。貫通孔６は本例では２段としているが１段でもよい。
【００５７】
【発明の効果】
本発明の圧電振動子用容器によれば、絶縁基体と蓋体とを封止する封止材が五酸化燐３０〜４０質量％、一酸化錫３７〜５０質量％、酸化ナトリウム５〜１５質量％、酸化亜鉛１〜６質量％、酸化アルミニウム１〜４質量％および酸化珪素１〜３質量％を含むガラス成分にフィラーとしてコージェライト系化合物を外添加で１６〜４５質量％添加したものから成ることから、圧電振動子の特性を向上させるために圧電振動子片を絶縁基体に導電性の接着材で接着固定した後に真空中で加熱処理しても、絶縁基体側にあらかじめ被着させた封止材のガラス成分が揮発してガラスの結晶化が進むことはなく、絶縁基体と蓋体との極めて強固な封着が可能となり、その結果、容器内部の圧電振動子片にそのＱ値を低下させたりその表面電極を酸化腐食させてしまうという悪影響を与えるような容器内部の真空度の低下を抑えることが可能になり、圧電振動子をその特性に劣化招来することなく気密に封止し、長期間にわたり安定に作動させることが可能となる。
【００５８】
また、本発明の圧電振動子用容器によれば、上面に圧電振動子片を搭載する凹部を有する絶縁基体と、絶縁基体の上面に凹部を覆うように封止材を介して接合され、絶縁基体との間の空間に圧電振動子片を収容するとともに上面から下面にかけて貫通孔が設けられた略平板状の蓋体とから成ることから、携帯電話等の移動体通信機器の小型・薄型化にともない圧電振動子を薄型化したとしても、ボード実装後に応力の集中する絶縁基体側に真空排気用の貫通孔が存在しないため、容器内部の圧電振動子片にそのＱ値を低下させたりその表面電極を酸化腐食させてしまうという悪影響を与えるような容器内部の真空度の低下を抑えることが可能になり、その結果、圧電振動子をその特性に劣化招来することなく気密に封止し、長期間にわたり安定に作動させることが可能となる。
【００５９】
さらに、本発明の圧電振動子用容器によれば、絶縁基体と蓋体とを接合させる封止材は、酸化鉛を含まないガラスで構成したことから、人体に害を与えたり地球環境に負荷を与えることはない。
【図面の簡単な説明】
【図１】本発明の圧電振動子用容器の実施の形態の一例を示す断面図である。
【符号の説明】
１・・・・・・絶縁基体
１ａ・・・・・凹部
２・・・・・・蓋体
３・・・・・・圧電振動子片
４・・・・・・メタライズ配線層
６・・・・・・貫通孔
１０・・・・・封止材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a container for a piezoelectric vibrator for accommodating a piezoelectric vibrator piece, and more particularly to a container for a piezoelectric vibrator for sealing using glass as a sealing material.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a piezoelectric vibrator is manufactured by hermetically housing a piezoelectric vibrator piece in a piezoelectric vibrator container.
A container for a piezoelectric vibrator that accommodates such a piezoelectric vibrator piece in an airtight manner is made of, for example, a ceramic such as an aluminum oxide sintered body, and has a concave portion for mounting the piezoelectric vibrator piece in a substantially central portion of an upper surface thereof. A piezoelectric vibrator is formed in the space between the insulating substrate and the insulating substrate by being joined to the upper surface of the insulating substrate via a sealing material such as low-melting-point glass. And a lid for accommodating the pieces.
[0003]
Further, the piezoelectric vibrator piece accommodated in the container is, for example, 1.3 × 10 ^-2 In the case of a piezoelectric vibrator piece requiring vacuum sealing of about Pa, a through hole for evacuating the space between the insulating base and the lid to a vacuum is formed from the upper surface to the lower surface of the insulating base. I have. Then, a piezoelectric vibrator piece is adhered and fixed to the inside of the container including the insulating base and the lid with a conductive adhesive, and heat-treated in a vacuum. The space accommodating the child pieces is evacuated to a vacuum, and thereafter, the through-hole is filled with a sealing member made of a brazing material such as a gold-tin alloy to seal the through-hole, whereby the piezoelectric vibrator is formed. A piezoelectric vibrator in which a piezoelectric vibrator piece is hermetically housed inside a container for use.
[0004]
The sealing material for sealing the insulating base and the lid is usually attached to the insulating base before the piezoelectric vibrator piece is fixed to the insulating base with a conductive adhesive. Such sealing materials include, for example, 50 to 65% by weight of lead oxide, 2 to 10% by weight of boron oxide, 1 to 6% by weight of zinc oxide, 10 to 30% by weight of lead fluoride, and 10 to 20% of bismuth oxide. A lead-based glass in which a lead titanate compound is added as a filler in an amount of 26 to 45% by weight to a glass component containing the same by weight is used.
[0005]
[Problems to be solved by the invention]
However, this conventional piezoelectric vibrator uses lead oxide of 50 to 65% by weight, boron oxide of 2 to 10% by weight, zinc oxide of 1 to 6% by weight, and lead fluoride as sealing materials for joining the lid to the insulating base. Since a lead-based glass in which a lead titanate compound is added as a filler to a glass component containing 10 to 30% by weight and bismuth oxide 10 to 20% by weight as a filler is used, the piezoelectric vibrator piece is electrically conductive. When heat treatment is performed in a vacuum after bonding and fixing with a non-conductive adhesive, the fluorine component in the sealing material previously applied to the insulating substrate is volatilized, and the glass of the sealing material is crystallized. There is a problem that it is difficult to firmly join the lid and the lid, which lowers the degree of vacuum inside the vacuum-sealed container, lowers the Q value of the piezoelectric vibrator piece, and oxidizes and corrodes the surface electrode. Was.
[0006]
In addition, as mobile communication devices such as mobile phones have become smaller and thinner, there has been a further demand for smaller and thinner piezoelectric vibrators, and containers having a through hole formed from the upper surface to the lower surface of a conventional insulating substrate have been used. With a container structure that exhausts the internal space to a vacuum, the mechanical strength after mounting is reduced, and it cannot withstand the mechanical stress and impact applied to the mobile communication device, causing cracks in the insulating base or sealing material However, there is a possibility that the degree of vacuum inside the vacuum-sealed container is reduced, the Q value of the piezoelectric vibrator piece is reduced, and the surface electrode thereof is oxidized and corroded.
[0007]
Furthermore, in recent years, with the rise of the global environmental protection movement, lead oxide has been designated as an environmentally hazardous substance.For example, when an electronic device containing lead oxide is discarded or left outdoors and exposed to the weather, lead oxide is contained in the environment. However, the development of a sealing material that does not use lead oxide, which is harmful to the human body since it may melt and pollute the environment, has been required.
[0008]
The present invention has been devised in view of the above problems, and has as its object to hermetically seal a piezoelectric vibrator piece in a vacuum inside a container formed of an insulating base and a lid, and to reduce deterioration in its characteristics. An object of the present invention is to provide a container for a piezoelectric vibrator which can operate the piezoelectric vibrator normally and stably for a long period of time without inviting.
[0009]
[Means for Solving the Problems]
The container for a piezoelectric vibrator of the present invention is joined to an insulating base having a concave portion for mounting a piezoelectric vibrator piece on an upper surface, and a sealing material on the upper surface of the insulating base so as to cover the concave portion. A piezoelectric vibrator container comprising a substantially flat lid provided with a through hole from the upper surface to the lower surface for accommodating the piezoelectric vibrator piece in a space between the piezoelectric vibrator piece and the sealing material. To 40% by mass, 37 to 50% by mass of tin monoxide, 5 to 15% by mass of sodium oxide, 1 to 6% by mass of zinc oxide, 1 to 4% by mass of aluminum oxide and 1 to 3% by mass of silicon oxide The filler is characterized by comprising a cordierite-based compound added as an external additive in an amount of 16 to 45% by mass.
[0010]
According to the container for a piezoelectric vibrator of the present invention, the sealing material for sealing the insulating base and the lid is 30 to 40% by mass of phosphorus pentoxide, 37 to 50% by mass of tin monoxide, and 5 to 15% by mass of sodium oxide. %, Zinc oxide 1 to 6% by mass, aluminum oxide 1 to 4% by mass, and a glass component containing 16 to 45% by mass of a cordierite-based compound as a filler added to a glass component containing 1 to 3% by mass of silicon oxide. Therefore, even if the piezoelectric vibrator piece is adhered and fixed to the insulating base with a conductive adhesive to improve the characteristics of the piezoelectric vibrator, and then heat-treated in a vacuum, the sealing pre-applied to the insulating base can be performed. The crystallization of the glass does not proceed due to the volatilization of the glass component of the stopper, and an extremely strong seal between the insulating base and the lid can be obtained. As a result, the Q value is applied to the piezoelectric vibrator piece inside the container. Or oxidize the surface electrode. It is possible to suppress a decrease in the degree of vacuum inside the container, which has the adverse effect of causing the piezoelectric vibrator, to seal the piezoelectric vibrator airtight without deteriorating its characteristics, and to operate it stably for a long period of time Becomes possible.
[0011]
Further, according to the piezoelectric vibrator container of the present invention, the insulating base having the concave portion on which the piezoelectric vibrator piece is mounted on the upper surface is bonded to the insulating base via the sealing material so as to cover the concave portion on the upper surface. Since the piezoelectric vibrator piece is accommodated in the space between the base and a substantially flat lid with a through hole extending from the upper surface to the lower surface, a mobile communication device such as a mobile phone is reduced in size and thickness. Therefore, even if the piezoelectric vibrator is made thinner, since there is no through hole for evacuation on the insulating substrate side where the stress is concentrated after mounting the board, the Q value of the piezoelectric vibrator piece inside the container is reduced or the It is possible to suppress a decrease in the degree of vacuum inside the container, which has the adverse effect of oxidizing and corroding the surface electrode, and as a result, the piezoelectric vibrator is hermetically sealed without deteriorating its characteristics, Cheap for a long time It is possible to operate.
[0012]
Furthermore, according to the container for a piezoelectric vibrator of the present invention, since the sealing material for joining the insulating base and the lid is made of glass containing no lead oxide, it may harm the human body or load the earth environment. Will not give.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the container for a piezoelectric vibrator of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a piezoelectric vibrator container of the present invention and a piezoelectric vibrator using the same. In this figure, 1 is an insulating base, 2 is a lid, and 3 is a piezoelectric vibrator. Is a piece. Then, a piezoelectric vibrator is formed by hermetically sealing the piezoelectric vibrator piece 3 inside a container including the insulating base 1 and the lid 2.
[0014]
The insulating substrate 1 constituting the container for the piezoelectric vibrator is made of sintered aluminum oxide, sintered aluminum nitride, sintered silicon carbide, sintered silicon nitride, sintered mullite, sintered glass ceramic. It is made of an electrically insulating material such as a binder, and has a substantially square plate shape having a concave portion 1a for mounting the piezoelectric vibrator piece 3 at a substantially central portion of the upper surface thereof. 3 is bonded and fixed via an adhesive 5.
[0015]
The insulating substrate 1 has a width of 2 to 5 mm, a length of 5 to 10 mm, and a thickness of 0.3 to 0.6 mm, and the concave portion 1a has a width of 1 to 4 mm and a length of 4 to 9 mm. And the depth is 0.2 to 0.5 mm. With the demand for the piezoelectric vibrator piece 3 to be small and thin, the size and thickness of the piezoelectric vibrator piece 3 have been further increased.
[0016]
For example, when the insulating substrate 1 is made of an aluminum oxide-based sintered body, such an insulating substrate 1 may be made of an organic binder, a solvent, and a plastic suitable for a raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. A slurry and a dispersant are added and mixed to form a slurry, and the slurry is formed into a sheet using a sheet forming method such as a doctor blade method or a calender roll method, which is well known in the art, to form a ceramic green sheet (ceramic green sheet). After that, the ceramic green sheet is manufactured by subjecting the ceramic green sheet to an appropriate punching process, laminating a plurality of the green sheets, and firing at a high temperature of about 1600 ° C.
[0017]
In addition, a plurality of metallized wiring layers 4 are formed on the insulating substrate 1 from the bottom surface to the lower surface of the concave portion 1a. Each electrode of the piezoelectric vibrator piece 3 is electrically connected to a portion of the metallized wiring layer 4 located on the bottom surface of the concave portion 1 a via an adhesive 5. A wiring conductor (not shown) of the external electric circuit is attached via a brazing material such as a gold-tin alloy.
[0018]
For the metallized wiring layer 4, a metal paste obtained by adding a suitable melting point metal powder such as tungsten, molybdenum, manganese or the like to an appropriate organic solvent, solvent, plasticizer or the like is used, and a conventionally known thick film method such as a screen printing method is employed. Then, the ceramic green sheet serving as the insulating substrate 1 is printed and applied in advance, and is fired at the same time as the ceramic green sheet, so that the insulating substrate 1 is formed in a predetermined pattern from the bottom surface to the lower surface of the concave portion 1a.
[0019]
The metallized wiring layer 4 has a metal having good conductivity, good corrosion resistance and good wettability with a brazing material, such as nickel or gold, applied to the exposed surface to a thickness of 1 to 20 μm by plating. In addition, it is possible to effectively prevent oxidation corrosion of the metallized wiring layer 4 and to connect the metallized wiring layer 4 and the piezoelectric vibrator piece 3 via the adhesive 5 and to braze the metallized wiring layer 4 and the external electrodes. Can be made extremely strong.
[0020]
The adhesive 5 is made of, for example, silver-polyimide resin, and the piezoelectric vibrator piece 3 is placed via the adhesive 5 on one end of the metallized wiring layer 4 exposed on the bottom surface of the concave portion 1 a of the insulating base 1. Then, the bonding material 5 is heated to a temperature of about 300 ° C., subjected to a thermosetting treatment, and thermally cured to bond and fix the piezoelectric vibrator piece 3 to the insulating base 1. At this time, the heat resistance of the resinous adhesive material 5 can be improved by heat-treating the adhesive material 5 in a vacuum, and the piezoelectric vibrator piece due to the heat history received when the piezoelectric vibrator is mounted on the external circuit board 3 can be minimized.
[0021]
Further, the lid 2 is joined to the insulating base 1 via a sealing material 10. The lid 2 has a function of hermetically housing the piezoelectric vibrator piece 3 inside the container, and is made of, for example, a ceramic such as an aluminum oxide sintered body. The cover 2 has a through hole 6 formed at a substantially central portion from the bottom surface to the lower surface.
[0022]
The through hole 6 functions as an exhaust hole for accommodating the piezoelectric vibrator piece 3 in a container including the insulating base 1 and the lid 2 and then evacuating the space accommodating the piezoelectric vibrator piece 3 to a vacuum. I do. The through-hole 6 includes a first hole 6a on the upper surface of the lid 2 and a second hole 6b on the lower surface having an opening smaller than that of the first hole 6a. A sealing metal member 7 described below is attached to the periphery of the opening on the second hole 6b side, specifically, to the surface of a step formed between the first hole 6a and the second hole 6b. Metal layer 8 is applied.
[0023]
The first hole 6a and the second hole 6b preferably have circular openings, the first hole 6a has a diameter of 0.5 mm to 0.9 mm, and the second hole 6b has the first diameter. Has a diameter 0.1 mm to 0.4 mm smaller than the diameter of the hole 6a. However, the openings of the first hole 6a and the second hole 6b do not necessarily have to be circular, and the openings may be triangular, quadrangular or other shapes. The metal layer 8 applied to the periphery of the opening of the first hole 6a on the side of the second hole 6b has a part of the first hole 6a as long as it does not reach the upper surface of the lid 2. 6a may be slightly inserted.
[0024]
Then, in the metal layer 8 of the through-hole 6, the piezoelectric vibrator piece 3 is accommodated in the space between the insulating base 1 and the lid 2, and the space accommodating the piezoelectric vibrator piece 3 is evacuated to vacuum. Then, the sealing metal member 7 is attached via the brazing material 9. Thereby, the through-hole 6 is sealed, and the container for the piezoelectric vibrator is hermetically sealed.
[0025]
The metal layer 8 to which the sealing metal member 7 for sealing the through-hole 6 is attached is formed of a metallized metal layer using a metal powder such as tungsten carbide, molybdenum, silver, or copper. In order to improve the wettability, a plating metal layer (not shown) made of nickel, gold, or the like is applied to the surface as necessary.
[0026]
Since the metal layer 8 is attached around the opening of the first hole 6a on the side of the second hole 6b in the through hole 6, the brazing material 9 for attaching the metal member 7 for sealing is Since the metal layer 8 is spread only around the opening of the second hole 6b of the first hole 6a to which the metal layer 8 is attached, the sealing metal member 7 is attached to this metal layer 8 via the brazing material 9. Thus, when sealing the through hole 6, the brazing material 9 does not reach the upper and lower surfaces of the lid 2.
[0027]
Further, the metal member 7 for sealing is held around the opening of the second hole 6b of the first hole 6a by the surface tension of the molten brazing material 9, so that the brazing material 9 and the metal member 7 for sealing are It does not protrude from the lower surface of the lid 2 to hinder the vibration of the piezoelectric vibrator piece 3 or protrude from the upper surface of the lid 2 to hinder the mounting when the piezoelectric vibrator is mounted on an external circuit board. .
[0028]
The through-hole 6 is formed on the ceramic green sheet serving as the lid 2 by drilling a hole serving as the through-hole 6 in a predetermined size and shape in advance from the upper surface to the lower surface of the lid 2. It is formed to include a first hole 6a and a second hole 6b on the lower surface side smaller than the opening of the first hole 6a.
[0029]
The metal layer 8 is formed on the lid 2 by firing a metal paste obtained by adding and mixing an appropriate organic binder and a solvent to a metal powder such as tungsten together with a ceramic green sheet serving as the insulating base 1. In the through hole 6, the first hole 6a is covered around the opening on the second hole 6b side, specifically, on the upper surface of the step formed between the first hole 6a and the second hole 6b. Be worn.
[0030]
The sealing metal member 7 for sealing the through hole 6 is a sphere made of a metal such as copper, for example, and the brazing material 9 for attaching the sealing metal member 7 to the metal layer 8 is, for example, It is a brazing material made of an alloy such as a gold-tin alloy.
[0031]
Then, in the metal layer 8 of the through-hole 6, the piezoelectric vibrator piece 3 is accommodated in the space between the insulating base 1 and the lid 2, and the space accommodating the piezoelectric vibrator piece 3 is evacuated to vacuum. Then, the sealing metal member 7 is attached via the brazing material 9. Thereby, the through-hole 6 is sealed, and the container for the piezoelectric vibrator is hermetically sealed.
[0032]
The joining of the lid 2 to the insulating base 1 via the sealing member 10 is performed, for example, by first applying the sealing member 10 to the outer peripheral portion of the upper surface of the insulating base 1 in advance, and then attaching the piezoelectric vibrator piece 3 to the insulating base 1. After bonding and fixing to the insulating base 1 with the conductive bonding material 5, the conductive bonding material for bonding the piezoelectric vibrator is heated in vacuum, and the sealing material 10 is interposed between the conductive bonding material and the upper surface of the insulating base 1. This is performed by placing the lid 2 and finally heating and softening and melting the sealing material 10, followed by cooling and solidification.
[0033]
In order to previously apply the sealing material 10 to the outer peripheral portion of the upper surface of the insulating base 1, a glass paste serving as the sealing material 10 is printed and applied to the outer peripheral portion of the upper surface of the insulating base 1 by a screen printing method. After the paste is heated and softened and melted, it is cooled and solidified to adhere the sealing material 10 on the upper surface of the insulating base 1.
[0034]
In the piezoelectric vibrator container of the present invention, the sealing material 10 is composed of 30 to 40% by mass of phosphorus pentoxide, 37 to 50% by mass of tin monoxide, 5 to 15% by mass of sodium oxide, and 1 to 6% by mass of zinc oxide. And a glass component containing 1 to 4% by mass of aluminum oxide and 1 to 3% by mass of silicon oxide to which 16 to 45% by mass of a cordierite-based compound is externally added as a filler. This is important in the piezoelectric vibrator container of the present invention.
[0035]
According to the container for a piezoelectric vibrator of the present invention, the sealing material 10 is composed of 30 to 40% by mass of phosphorus pentoxide, 37 to 50% by mass of tin monoxide, 5 to 15% by mass of sodium oxide, and 1 to 6% by mass of zinc oxide. Since a cordierite-based compound is added as a filler to the glass component containing 1 to 4% by mass of aluminum oxide and 1 to 3% by mass of silicon oxide by external addition, 16 to 45% by mass, the sealing material 10 is made of fluorine. The piezoelectric vibrator piece 3 does not contain any components and does not volatilize even when it is maintained at a temperature equal to or higher than the softening point in a vacuum. In order to improve the frequency characteristics of the piezoelectric vibrator, the piezoelectric vibrator piece 3 is electrically conductive. Even if heat treatment is performed in a vacuum after bonding and fixing with the adhesive material 5, the components in the sealing glass previously applied to the insulating substrate 1 do not volatilize, and crystallization of the sealing glass by vacuum heating proceeds. Without, with lid 2 In addition, a strong seal can be achieved, and a decrease in the degree of vacuum inside the container, which adversely affects the Q value of the piezoelectric vibrator piece 3 inside the container or oxidizes and corrodes the surface electrode thereof, is suppressed. It becomes possible. As a result, the piezoelectric vibrator piece 3 can be hermetically sealed without deteriorating its characteristics, and can be operated stably for a long period of time.
[0036]
If the amount of phosphorus pentoxide in the glass component of the sealing material 10 is less than 30% by mass, the softening and melting temperature of the glass becomes high, and it becomes difficult to hermetically seal the container at a low temperature. On the other hand, if it exceeds 40% by mass, the chemical resistance of the glass tends to decrease, and the reliability of hermetic sealing of the container tends to greatly decrease. Therefore, the amount of phosphorus pentoxide is preferably in the range of 30 to 40% by mass.
[0037]
If the amount of tin monoxide is less than 37% by mass, the softening / melting temperature of the glass tends to be high, and the hermetic sealing of the container at low temperatures tends to be difficult. The chemical resistance of the glass tends to decrease, and the reliability of hermetic sealing of the container tends to greatly decrease. Therefore, the amount of tin monoxide is preferably in the range of 37 to 50% by mass.
[0038]
Further, if the amount of sodium oxide is less than 5% by mass, the softening and melting temperature of the glass tends to be high, and the hermetic sealing of the container at a low temperature tends to be difficult. , The chemical resistance tends to decrease, and the reliability of hermetic sealing of the container tends to decrease significantly. Therefore, the amount of sodium oxide is preferably in the range of 5 to 15% by weight.
[0039]
If the zinc oxide content is less than 1% by mass, the chemical resistance of the glass tends to be reduced, and the reliability of hermetic sealing of the container tends to be greatly reduced. It tends to be difficult to hermetically seal the container at a low temperature. Therefore, the amount of zinc oxide is preferably in the range of 1 to 6% by mass.
[0040]
If the amount of aluminum oxide is less than 1% by mass, the moisture resistance of the glass tends to decrease, and the reliability of hermetic sealing of the container via the sealing material 10 tends to decrease. If the temperature exceeds the above range, the softening and melting temperature of the glass tends to be high, and it is difficult to hermetically seal the container at low temperatures. Therefore, the amount of aluminum oxide is preferably in the range of 1 to 4% by mass.
[0041]
If the amount of silicon oxide is less than 1% by mass, the coefficient of thermal expansion of the glass becomes large and greatly differs from the coefficients of thermal expansion of the insulating base 1 and the lid 2, and the reliability of hermetic sealing of the container becomes poor. On the other hand, if it exceeds 3% by mass, the softening and melting temperature of the glass becomes high, and it becomes difficult to hermetically seal the container at a low temperature. Therefore, the amount of silicon oxide is preferably in the range of 1 to 3% by mass.
[0042]
Further, when the amount of the cordierite-based compound is less than 16% by mass, the strength of the glass sealing material 10 tends to decrease, and the reliability of hermetic sealing of the container tends to greatly decrease, while exceeding 45% by mass. And the fluidity of the sealing material 10 at a low temperature tends to decrease, and the reliability of hermetic sealing of the container tends to decrease. Therefore, the amount of the cordierite-based compound is preferably in the range of 16 to 45% by mass.
[0043]
In addition, in the piezoelectric vibrator container of the present invention, since neither the brazing material 9 nor the sealing material 10 contains lead oxide, there is no harm to the human body and no load on the global environment.
[0044]
Thus, according to the container for a piezoelectric vibrator of the present invention, one end of the piezoelectric vibrator piece 3 is attached to the portion of the insulating base 1 located at the mounting portion 1a of the metallized wiring layer 4 via the adhesive 5 made of silver-polyimide or the like. At the same time, the electrodes of the piezoelectric vibrator piece 3 are electrically connected to the metallized wiring layer 4, and then the lid 2 is joined via the sealing material 10 so as to cover the mounting portion 1 a of the insulating base 1. By doing so, the piezoelectric vibrator piece 3 is accommodated in the space between the insulating base 1 and the lid 2. Further, the space between the insulating base 1 in which the piezoelectric vibrator piece 3 is accommodated and the lid 2 is evacuated to a vacuum so that the gas inside the space does not hinder the vibration of the piezoelectric vibrator piece 3. At the same time, the sealing metal member 7 is attached to the metal layer 8 in the through hole 6 formed in the insulating base 1 via the brazing material 9 to be hermetically sealed. At this time, the piezoelectric vibrator can obtain a high Q since the space in the container accommodating the piezoelectric vibrator piece 3 is evacuated to a vacuum.
[0045]
【Example】
The following experiment was performed to confirm the effect. Here, an experimental example is shown in which the amounts of the main components phosphorus pentoxide, tin monoxide and the externally added filler are determined.
First, glass was produced by changing the mass% of each component. Then, in order to evaluate the airtight reliability of the container using each glass, a helium gas leak test was performed on the sealed container after 1000 cycles of the thermal shock test. Further, in order to compare the sealing strength of the lid, the shear strength between the container and the metal body was measured. In addition, as a container for evaluation, the vertical dimension of the insulating base was 5.0 mm, the horizontal dimension was 3.2 mm, the height was 0.7 mm, and the width of the joint surface with the lid was 0.5 mm. Was used.
[0046]
(Experiment 1)
Phosphorus pentoxide was changed in the range of 25 to 45% by mass, and other components were added so that the total was 100% by mass (rounded to two decimal places). Table 1 shows the experimental results at this time.
[0047]
[Table 1]

[0048]
From the experimental results, it was found that phosphorus pentoxide exhibits good airtightness reliability in the range of 30 to 40% by mass and a high shear strength of 50 N (Newton) or more.
[0049]
Next, the following experiment was performed on tin monoxide and phosphorus pentoxide.
(Experiment 2)
The content of phosphorus pentoxide is in the range of 30 to 40% by mass, the content of tin monoxide is changed between 30 to 55% by mass, and other components are added so that the total becomes 100% by mass. Compounded (rounded to two decimal places). Table 2 shows the results.
[0050]
[Table 2]

[0051]
From the experimental results, it was found that tin monoxide exhibits good hermetic reliability in the range of 37 to 50% by mass and a high shear strength of 50 N (Newton) or more.
[0052]
The same type of experiment was conducted for trace elements, and the glass sealing material was found to contain 30 to 40% by mass of phosphorus pentoxide, 37 to 50% by mass of tin monoxide, 5 to 15% by mass of sodium oxide, and 1 to 6% by mass of zinc oxide. In the case of a glass containing 1 to 4% by mass of aluminum oxide and 1 to 3% by mass of silicon oxide, it has been found that a high shear strength of 50 N (Newton) or more can be obtained while exhibiting good airtightness reliability. The effect of was able to be confirmed.
[0053]
(Experiment 3)
Further, the same experiment was performed with the glass composition being fixed and the filler addition amount being changed. Table 3 shows the evaluation results.
[0054]
[Table 3]

[0055]
It was found that when the cordierite-based compound was externally added as a filler, 16 to 45% by mass was added, good airtightness reliability was obtained, and high shear strength of 50 N (Newton) or more was obtained.
[0056]
The present invention is not limited to the above-described embodiment, and various changes and improvements may be made without departing from the scope of the present invention. Although the through hole 6 has two steps in this example, it may have one step.
[0057]
【The invention's effect】
According to the container for a piezoelectric vibrator of the present invention, the sealing material for sealing the insulating base and the lid is 30 to 40% by mass of phosphorus pentoxide, 37 to 50% by mass of tin monoxide, and 5 to 15% by mass of sodium oxide. %, Zinc oxide 1 to 6% by mass, aluminum oxide 1 to 4% by mass, and a glass component containing 16 to 45% by mass of a cordierite-based compound as a filler added to a glass component containing 1 to 3% by mass of silicon oxide. Therefore, even if the piezoelectric vibrator piece is adhered and fixed to the insulating base with a conductive adhesive to improve the characteristics of the piezoelectric vibrator, and then heat-treated in a vacuum, the sealing pre-applied to the insulating base can be performed. The crystallization of the glass does not proceed due to the volatilization of the glass component of the stopper, and an extremely strong seal between the insulating base and the lid can be obtained. As a result, the Q value is applied to the piezoelectric vibrator piece inside the container. Or oxidize the surface electrode. It is possible to suppress a decrease in the degree of vacuum inside the container, which has the adverse effect of causing the piezoelectric vibrator, to seal the piezoelectric vibrator airtight without deteriorating its characteristics, and to operate it stably for a long period of time Becomes possible.
[0058]
Further, according to the piezoelectric vibrator container of the present invention, the insulating base having the concave portion on which the piezoelectric vibrator piece is mounted on the upper surface is bonded to the insulating base via the sealing material so as to cover the concave portion on the upper surface. Since the piezoelectric vibrator piece is accommodated in the space between the base and a substantially flat lid with a through hole extending from the upper surface to the lower surface, a mobile communication device such as a mobile phone is reduced in size and thickness. Therefore, even if the piezoelectric vibrator is made thinner, since there is no through hole for evacuation on the insulating substrate side where the stress is concentrated after mounting the board, the Q value of the piezoelectric vibrator piece inside the container is reduced or the It is possible to suppress a decrease in the degree of vacuum inside the container, which has the adverse effect of oxidizing and corroding the surface electrode, and as a result, the piezoelectric vibrator is hermetically sealed without deteriorating its characteristics, Cheap for a long time It is possible to operate.
[0059]
Furthermore, according to the container for a piezoelectric vibrator of the present invention, since the sealing material for joining the insulating base and the lid is made of glass containing no lead oxide, it may harm the human body or load the earth environment. Will not give.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of a container for a piezoelectric vibrator according to the present invention.
[Explanation of symbols]
1 ... Insulating substrate
1a .... recess
2 Lid
3. Piezoelectric vibrator piece
4 Metallized wiring layer
6 ... Through-hole
10 .... Sealant

Claims

An insulating base having a concave portion for mounting the piezoelectric vibrator piece on the upper surface, and an insulating substrate joined to the upper surface of the insulating base via a sealing material so as to cover the concave portion; A piezoelectric vibrator container comprising a substantially flat lid provided with a through hole from the upper surface to the lower surface for accommodating a vibrator piece, wherein the sealing material is 30 to 40% by mass of phosphorus pentoxide, Cordierite compound as a filler in a glass component containing 37 to 50% by mass of tin oxide, 5 to 15% by mass of sodium oxide, 1 to 6% by mass of zinc oxide, 1 to 4% by mass of aluminum oxide and 1 to 3% by mass of silicon oxide Characterized by the external addition of 16 to 45% by mass.