JP2005026974A

JP2005026974A - Method of manufacturing piezoelectric vibration device and piezoelectric vibration device manufactured by the method

Info

Publication number: JP2005026974A
Application number: JP2003189628A
Authority: JP
Inventors: Hiroshi Shiromizu; 浩史白水
Original assignee: Daishinku Corp
Current assignee: Daishinku Corp
Priority date: 2003-07-01
Filing date: 2003-07-01
Publication date: 2005-01-27

Abstract

<P>PROBLEM TO BE SOLVED: To exclude a bad influence on the characteristics of the sealing material running over in a ceramic package without increasing the manufacturing cost and to suppress the reduction of sealing strength and the reduction of airtightness of the ceramic package. <P>SOLUTION: In a method of manufacturing a piezoelectric vibration device which is provided with a substrate 1, a piezoelectric vibrating element 3, and a cover 2 and is hermetically sealed through a sealing material G, a bank part and a recessed part are formed in at least one of the cover and the substrate, and the end face of the bank part is coated throughout with a first sealing material, and the upper part of the first sealing material is coated with a second sealing material, and the second sealing material is applied with intervals to the corner parts of the end face of the bank part, and a piezoelectric diaphragm is mounted on the substrate through a conductive binder, and an opening part of the cover is put over an opening part of the substrate, and the first sealing material and the second sealing material are fused by heating to hermetically seal the piezoelectric vibration device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、セラミック基体とセラミック蓋とを低融点ガラス等の封止材により封止してなる圧電振動デバイスの製造方法およびその方法によって製造された圧電振動デバイスに関するものである。
【０００２】
【従来の技術】
気密封止を必要とする圧電振動デバイスの例として、水晶振動子、水晶フィルタ、水晶発振器あるいはＳＡＷフィルタ等があげられる。これらはいずれも水晶振動板（圧電振動素子）の表面に金属薄膜電極を形成し、この金属薄膜電極を外気から保護するため、気密封止されている。
【０００３】
これら圧電振動デバイスは部品の表面実装化の要求から、セラミックパッケージに気密的に収容する構成が増加している。このようなセラミックパッケージを用いる場合、セラミックの基体と蓋との接合は多種多様の接合方法が検討されている。例えばはんだ接合、樹脂接合、低融点ガラス接合、抵抗溶接、電子ビーム溶接等各種の接合方法等があげられるが、よく用いられる接合方法の１つとして、低融点ガラス等の封止材による気密封止がある。
【０００４】
この低融点ガラスによる気密封止は、低背化が可能であり、圧電振動素子の収容領域が比較的広く確保でき、しかも接合の際、多数個の接合を一括して行えるバッチ処理が可能となるため、製造コストを低下させる利点を有している。
【０００５】
しかしながら、低融点ガラスなどの封止材による気密封止では、封止材の塗布量や気密封止後の塗布状態の管理が必要となる。封止材の塗布量が過少状態では気密不良や封止強度の低下を招き、封止材の塗布量が過多状態では、封止材のはみ出し、はみ出した封止材と圧電振動素子が接触して特性の異常を招くことがあった。
【０００６】
特に、圧電振動素子のサイズが比較的大きな低周波タイプのものでは、収容スペースを広く取るために、堤部を有する基体と、当該基体の堤部に対応した堤部を有する蓋とを用いたパッケージ形態であり、堤部の上面のみの面積の小さな封止エリアとなるため、上記封止材のはみ出しを招くことが多かった。この封止材のはみ出しは、堤部の角部分で封止材の塗布量が多くなるので、この部分で最も多く発生していた。また、圧電振動素子は、電極パッドや導電性接合材を介して基体上面から浮いた状態で搭載されているので、このはみ出した封止材と圧電振動素子が接触しやすい。
【０００７】
従来、これら封止材のはみ出しをなくすために、特許文献１に開示されているように、基体の堤部の角部分に、封止材料の非塗布部を設ける手法があった。
【０００８】
【特許文献１】
特開２００３−８３８２号公報
【０００９】
【発明が解決しようとする課題】
しかしながら、特許文献１のような手法では、封止材が封止面に全く塗布されない領域が形成されているため、封止材溶融後もこの領域の一部が残存し、封止強度が著しく低下することがあった。
また、特許文献１のように封止材が形成された基体の堤部に蓋を被せ、封止材を溶融させて気密封止する際に、加熱炉の熱により、パッケージ内のガス圧力が高まり、当該膨張したガスが封止材をパッケージの外部に押し出し、封止材を突き破って、パッケージ外部に噴出し、封止材の一部に隙間が形成され、気密性の著しい低下を招くといった問題もあった。
【００１０】
本発明は上記問題点を解決するためになされたもので、製造コストを増大させることなく、セラミックパッケージの封止材のはみ出しによる特性の悪影響をなくし、かつセラミックパッケージの封止強度の低下と気密性の低下を抑制できるより安価でより信頼性の高い圧電振動デバイスの製造方法およびその方法によって製造された圧電振動デバイスを提供することを目的とするものである。
【００１１】
【課題を解決するための手段】
上記課題を解決するために、平面多角形状のセラミックの基体と、当該基体に搭載される圧電振動素子と、前記基体の平面形状に対応したセラミックの蓋とを具備してなり、封止材を介して前記基体と前記蓋を接合し、気密封止してなる圧電振動デバイスの製造方法であって、前記蓋、または前記基体の少なくとも一方には、堤部と凹部が形成されており、当該堤部の端面全体に、第１の封止材を塗布し、当該第１の封止材の上部に、第１の封止材と同材質で、一層以上の第２の封止材を塗布してなるとともに、当該第２の封止材は、前記堤部の端面の角部にてお互いに隔離した状態で塗布し、前記第１に封止材と第２の封止材の表面を硬化してなる工程、前記基体に圧電振動板が導電性接合材を介して基体上面から浮いた状態で搭載されてなる工程、前記基体の開口部に前記蓋の開口部を重ね合わせ、前記第１の封止材と第２の封止材を加熱溶融させて気密封止する工程を経てなることを特徴とする。
【００１２】
また、特許請求項２の製造方法では、上述の製造方法において、前記第２の封止材は、一定の間隔で同一幅の隙間を有した状態で塗布されてなることを特徴とする。
【００１３】
また、特許請求項３の製造方法では、上述の製造方法において、前記第１の封止材の厚みに対して、第２の封止材の厚みを１〜２倍の厚みで塗布してなることを特徴とする。
【００１４】
また、特許請求項４の製造方法では、上述の製造方法において、前記第１の封止材と第２の封止材は、前記蓋、または前記基体の一方の堤部のみに形成されてなることを特徴とする。
【００１５】
また、特許請求項５では、上述の製造方法によって製造されたことを特徴とする圧電振動デバイス。
【００１６】
【発明の効果】
本発明の特許請求項１によれば、前記蓋、または前記基体の少なくとも一方の堤部の端面全体に、第１の封止材を塗布されているので、封止材が全く塗布されない領域が形成されず、封止材の過少状態による気密不良や封止強度の低下を招くことがない。また、第２の封止材は、前記堤部の端面の角部にてお互いに隔離した状態で塗布されているので、この領域で封止材全体として厚みが増大することがなく、封止材の過多状態による封止材のはみ出すことがなくなる。
【００１７】
しかも、第２の封止材は、前記堤部の端面の角部にてお互いに隔離した状態で塗布され、前記第１に封止材と第２の封止材の表面を硬化しているので、基体の堤部に蓋の堤部を重ね合わせた際、前記角部分の封止材の隙間により、封止材が溶融するまで、蓋と基体の凹部内のガス圧力が高まっても、確実にガス抜きを行い、封止材が溶融すると、同材質からなる第１の封止材の上部に第２の封止材がなじんで確実に広がり、この隙間を確実に塞ぐことができる。このため、圧電振動デバイスの封止強度を低下させることなく、気密不良を招くともない。
【００１８】
さらに、封止材を第１の封止材と、一層以上の第２の封止材を分けて塗布することにより、所望の領域で厚み調整がなされた封止材がスクリーン印刷などの手法により容易に作成できるとともに、封止材の厚みを調整しやすい。
【００１９】
また本発明の特許請求項２によれば、前記第２の封止材は、一定の間隔で同一幅の隙間を有した状態で塗布されているので、上述の作用効果に加え、封止材に堤部を横切る一定幅の溝が形成され、この溝部分で均一に第２の封止材が広がり、封止材のはみ出しがより軽減される。
【００２０】
また本発明の特許請求項３によれば、前記第１の封止材の厚みに対して、第２の封止材の厚みを１〜２倍の厚みで塗布されているので、上述の作用効果に加え、封止材溶融前のガス抜きと封止材溶融後の隙間を塞ぐ働きがより効率的に行われる。１倍より小さいときはガス抜き効率が低下し、２倍より大きいときは、隙間が残存する可能性が高くなる。
【００２１】
また本発明の特許請求項４によれば、前記第１の封止材と第２の封止材は、前記蓋、または前記基体の一方の堤部のみに形成されているので、上述の作用効果に加え、封止の信頼性を低下させることなく、コストを低減させることができる。
【００２２】
このように本発明の製造方法により、製造コストを増大させることなく、セラミックパッケージの封止材のはみ出しによる特性の悪影響をなくし、かつセラミックパッケージの封止強度の低下と気密性の低下を抑制できるより安価で信頼性の高い圧電振動デバイスを提供することができる。
【００２３】
また本発明の特許請求項４によれば、上述の方法によって製造された圧電振動デバイスであるので、製造コストを増大させることなく、セラミックパッケージの封止材のはみ出しによる特性の悪影響をなくし、かつセラミックパッケージの封止強度の低下と気密性の低下を抑制できるより安価で信頼性の高い圧電振動デバイスが得られる。
【００２４】
【発明の実施の形態】
本発明の第１の実施形態による圧電振動デバイスとして、表面実装型水晶振動子を例にして、図面とともに説明する。図１は本発明の第１の実施形態を示す模式的な断面図であり、図２は図１の蓋の底面図であり、図３は図２のＡ−Ａ線に沿った断面図である。
【００２５】
表面実装型水晶振動子は、全体として直方体形状で、上部が開口した凹部を有する平面矩形状のセラミック基体１と、当該基体の凹部の中に収容される矩形水晶振動板（圧電振動素子）３と、下部が開口した凹部を有する平面矩形状のセラミック蓋２とを具備しており、前記セラミック基体の凹部分とセラミック蓋の逆凹部分により、圧電振動素子の収容スペース（搭載スペース）を形成している。
【００２６】
セラミック基体１は、断面でみて凹形状で、方形の周をなす堤部１１と凹部１２とを有しており、当該凹部の内部には、短辺方向に並んで電極パッド１３，１４が形成されている（電極パッド１４については図示せず）。これら電極パッドは図示しない引出電極により、セラミック基体の底面に導出されている。
【００２７】
セラミック蓋２は、断面でみて逆凹形状で、前記基体の堤部１１に対応した方形の周をなす堤部２１と凹部２２を有している。
【００２８】
これらのセラミック基体１とセラミック蓋２は、セラミック積層技術により容易に作成できる。すなわち、各種の形状に対応したセラミックグリーンシートを用い、当該セラミックグリーンシートにメタライズ形成するとともに一体焼成することで作成できる。
【００２９】
上述のように構成されたセラミック蓋の堤部の端部には、低融点ガラスＧ（封止材）がスクリーン印刷などの手法により形成されている。蓋の堤部に形成される低融点ガラスは、前記蓋の堤部の端面全体に、第１の低融点ガラスＧ１が塗布されており、この第１の低融点ガラス層の上面には、前記堤部の角部２３，２４，２５，２６にて、各辺の第２の低融点ガラスＧ２がお互いに一定の間隔で同一幅の隙間を有した状態で塗布形成されている。このため、図２に示すように、前記堤部の角部分では、第１の低融点ガラスのみが塗布され、低融点ガラスの一部に堤部を横切る厚みの薄い段差領域（堤部を横切る一定幅の溝）が形成されるので、後述する封止で溶融される際、この隙間部分で均一に第２の低融点ガラスが広がり、封止材のはみ出しがより軽減される。また、このとき、前記第１の低融点ガラスの塗布される厚みに対して、第２の低融点ガラスの塗布される厚みを１〜２倍の厚みで設定しているので、封止材溶融前のガス抜きと封止材溶融後の隙間を塞ぐ働きがより効率的に行われる。この状態で、上記塗布された低融点ガラスの融点より低い温度で加熱し、乾燥することで、前記第１の低融点ガラスと第２の低融点ガラスの表面を硬化している。（第１の工程）
前記基体の電極パッド１３，１４には、矩形の水晶振動板３が導電性接合材Ｓを介して基体上面から浮いた状態で搭載され、長辺方向の一端を片持ち支持する構成となっている。水晶振動板３の表裏面には図示していないが一対の励振電極が形成され、各々電極パッド１３，１４部分に引き出されており、導電性接合材Ｓにより導電接合されている。（第２の工程）
前記セラミック基体の堤部１１の上に、荷重をかけて前記セラミック蓋の堤部２１を搭載し、不活性ガスを充填した状態で加熱炉に所定時間投入し（例えば、３２０〜３５０℃の温度で１０分程度）、前記低融点ガラスＧ１およびＧ２を溶融させ、その後常温に冷やすことで前記低融点ガラスを硬化し、気密封止される。量産性を考慮した場合、このようなセラミック基体とセラミック蓋のペアを多数個用意し、これらを加熱硬化炉に所定時間投入し低融点ガラスを硬化させるとよい。（第３の工程）
なお、上記第１の実施形態では、気密封止工程の前（前記第２工程の後）に、前記水晶振動板３が搭載されたセラミック基体１に対して、アニール工程を実施し、その後、気密封止工程（第３の工程）に移行している。このため、水晶振動板を電気的機械的に接続する導電性接合材の応力緩和などが行え、より信頼性の高い圧電振動デバイスが提供できる。
【００３０】
以上により、表面実装型水晶振動子の完成となる。
【００３１】
上記第１の実施形態では、蓋の堤部のみに低融点ガラス（封止材）を形成しているが、基体の堤部のみに同様の低融点ガラス（封止材）形成してもよく、蓋の堤部と基体の堤部の両方に同様の低融点ガラス（封止材）を形成してもよい。さらに、上記実施形態では、第１の低融点ガラス層と第２の低融点ガラス層をともに単層で構成しているが、少なくとも一方を、２層以上の低融点ガラスから構成してもよい。
【００３２】
次に、本発明の第２の実施形態による圧電振動デバイスを、表面実装型の水晶振動子を例にし、図面とともに説明する。図４は本発明の第２の実施形態を示す蓋の底面図であり、図５は図４のＢ−Ｂ線に沿った断面図である。なお、前記実施形態と同様の部分については同番号を付すとともに説明の一部を割愛した。
【００３３】
セラミック蓋１とセラミック基体２の堤部の端部には、低融点ガラス（封止材）がスクリーン印刷などの手法により形成されている。蓋と基体の堤部に形成される低融点ガラスは、当該蓋と基体の堤部の端面全体に、第１の低融点ガラスＧ１が塗布されている（基体については図示せず）。前記蓋の第１の低融点ガラス層の上面には、前記堤部の角部２３，２４，２５，２６と堤部の長辺方向の中央部分２７，２８にて、各辺の第２の低融点ガラスＧ２がお互いに隔離した状態で塗布形成されている。このため、図４に示すように、前記堤部の角部分と長辺方向の中央部分では、第１の低融点ガラスのみが塗布され、低融点ガラスの一部に堤部を横切る厚みの薄い段差領域が形成されており、堤部の角部分のみならず長辺方向の中央部分でも、低融点ガラスのはみ出し抑制とガス抜け性の向上がなされている。また、このとき、前記第１の低融点ガラスの塗布される厚みに対して、第２の低融点ガラスの塗布される厚みを１〜２倍の厚みで設定しているので、封止材溶融前のガス抜きと封止材溶融後の隙間を塞ぐ働きがより効率的に行われる。この状態で、上記塗布された低融点ガラスの融点より低い温度で加熱し、乾燥することで、前記第１の低融点ガラスと第２の低融点ガラスの表面を硬化している。（第１の工程）
第１の実施形態と同様に、前記基体の電極パッド１３，１４には、矩形の水晶振動板３が導電性接合材Ｓを介して基体上面から浮いた状態で搭載され、長辺方向の一端を片持ち支持する構成となっている。（第２の工程）
前記水晶振動板３が搭載されたセラミック基体１に対して、アニール工程を実施する。（第３の工程）
前記セラミック基体の堤部１１の上に、前記セラミック蓋の堤部２１を搭載し、不活性ガスを充填した状態で加熱炉に所定時間投入し（例えば、３２０〜３５０℃の温度で１０分程度）、前記低融点ガラスＧ１およびＧ２を溶融させ、その後常温に冷やすことで前記低融点ガラスを硬化し、気密封止される。量産性を考慮した場合、このようなセラミック基体とセラミック蓋のペアを多数個用意し、これらを加熱硬化炉に所定時間投入し低融点ガラスを硬化させるとよい。（第４の工程）
なお、上記第２の実施形態では、気密封止工程の後（前記第４工程の後）にも、前記気密封止されたセラミック基体１とセラミック蓋２に対して、アニール工程を実施している。このため、気密封止された圧電振動デバイスの経時変化に対する特性の向上が行え、より信頼性の高い圧電振動デバイスが提供できる。
【００３４】
以上により、表面実装型水晶振動子の完成となる。
【００３５】
上記第２の実施形態では、蓋の堤部に第１の低融点ガラス（第１の封止材）と第２の低融点ガラス（第２の封止材）を形成し、基体の堤部に第１の低融点ガラス（第１の封止材）を形成しているので、溶融後の離隔した第２の低融点ガラス（第２の封止材）が、蓋体と基体の両方に形成された第１の低融点ガラスになじんでより広がりが促進され、確実に段差による隙間を塞ぐことができ、封止強度をさらに向上させる。
【００３６】
なお、基体の堤部に第１の低融点ガラス（第１の封止材）と第２の低融点ガラス（第２の封止材）を形成し、蓋の堤部に第１の低融点ガラス（第１の封止材）を形成しても同様の効果が得られる。さらに、上記実施形態では、第１の低融点ガラス層と第２の低融点ガラス層をともに単層で構成しているが、少なくとも一方を、２層以上の低融点ガラスから構成してもよい。
【００３７】
上記実施形態では、封止材料として低融点ガラスの例を示したが、エポキシ系の樹脂接着剤、はんだ等の金属ろう材でも適用できる。セラミックパッケージの形態として、前記蓋と前記基体の両方に堤部を有するものを例にしているが、蓋のみ、あるいは基体のみ堤部を有するものにも適用できる。圧電振動デバイスの保持形態として、片端保持構造のものを例にしているが、両端保持構造のものにも適用できる。さらに、圧電振動デバイスの例として、水晶振動子の例を示したが、もちろん、水晶発振器、水晶フィルタ、ＳＡＷフィルタ等の他の圧電振動デバイスにも適用できる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態を示す模式的な断面図。
【図２】図１の蓋の底面図。
【図３】図２のＡ−Ａ線に沿った断面図。
【図４】本発明の第２の実施形態を示す蓋の底面図。
【図５】図４のＢ−Ｂ線に沿った断面図。
【符号の説明】
１セラミック基体
２セラミック蓋
３水晶振動板（圧電振動素子）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a piezoelectric vibration device in which a ceramic base and a ceramic lid are sealed with a sealing material such as low-melting glass, and a piezoelectric vibration device manufactured by the method.
[0002]
[Prior art]
Examples of the piezoelectric vibration device that requires hermetic sealing include a crystal resonator, a crystal filter, a crystal oscillator, and a SAW filter. These are all hermetically sealed in order to form a metal thin film electrode on the surface of a quartz crystal plate (piezoelectric vibration element) and protect the metal thin film electrode from the outside air.
[0003]
These piezoelectric vibration devices are increasingly being configured to be hermetically accommodated in a ceramic package due to the demand for surface mounting of components. When such a ceramic package is used, a wide variety of bonding methods have been studied for bonding the ceramic substrate and the lid. For example, various joining methods such as solder joining, resin joining, low melting glass joining, resistance welding, electron beam welding, etc. can be mentioned. One of the commonly used joining methods is air sealing with a sealing material such as low melting glass. There is a stop.
[0004]
This hermetic sealing with low-melting glass can reduce the height, can ensure a relatively large accommodation area of the piezoelectric vibration element, and can perform batch processing that can perform a large number of joints at the same time. Therefore, it has the advantage of reducing the manufacturing cost.
[0005]
However, in hermetic sealing with a sealing material such as low-melting glass, it is necessary to manage the coating amount of the sealing material and the application state after hermetic sealing. If the coating amount of the sealing material is too small, it will lead to poor airtightness and a decrease in sealing strength.If the coating amount of the sealing material is excessive, the sealing material will stick out and the protruding sealing material will contact the piezoelectric vibration element. May cause abnormal characteristics.
[0006]
Particularly, in the case of a low-frequency type having a relatively large size of the piezoelectric vibration element, a base having a bank part and a lid having a bank part corresponding to the bank part of the base body are used in order to make a large accommodation space. Since it is a package form and becomes a sealing area with a small area only on the upper surface of the bank portion, the sealing material often protrudes. The seal material protruded most frequently at the corner portion of the bank because the amount of the seal material applied increased. Further, since the piezoelectric vibration element is mounted in a state where it floats from the upper surface of the substrate via the electrode pad or the conductive bonding material, the protruding sealing material and the piezoelectric vibration element are likely to come into contact with each other.
[0007]
Conventionally, in order to eliminate the protrusion of these sealing materials, as disclosed in Patent Document 1, there has been a method of providing a non-application portion of a sealing material at a corner portion of a bank portion of a base.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-8382
[Problems to be solved by the invention]
However, in the technique such as Patent Document 1, since a region where no sealing material is applied to the sealing surface is formed, a part of this region remains even after the sealing material is melted, and the sealing strength is remarkably high. There was a decline.
Further, when the sealing material is formed on the bank portion of the base as in Patent Document 1, the sealing material is melted and hermetically sealed, and the gas pressure in the package is caused by the heat of the heating furnace. The expanded gas pushes the sealing material to the outside of the package, breaks through the sealing material, and is ejected to the outside of the package. A gap is formed in a part of the sealing material, resulting in a significant decrease in airtightness. There was also a problem.
[0010]
The present invention has been made to solve the above-described problems, eliminates the adverse effect of the characteristics due to the protrusion of the sealing material of the ceramic package without increasing the manufacturing cost, and reduces the sealing strength and airtightness of the ceramic package. It is an object of the present invention to provide a cheaper and more reliable method of manufacturing a piezoelectric vibration device capable of suppressing deterioration of the property, and a piezoelectric vibration device manufactured by the method.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a planar polygonal ceramic base, a piezoelectric vibration element mounted on the base, and a ceramic lid corresponding to the planar shape of the base are provided. A method of manufacturing a piezoelectric vibration device in which the base body and the lid are joined together and hermetically sealed, and at least one of the lid or the base body has a bank portion and a recess, The first sealing material is applied to the entire end face of the bank portion, and the second sealing material is applied to the upper portion of the first sealing material by the same material as the first sealing material. In addition, the second sealing material is applied in a state of being isolated from each other at the corners of the end face of the bank portion, and the surfaces of the sealing material and the second sealing material are firstly applied. A step of curing, wherein the piezoelectric vibration plate is mounted on the base body in a state of floating from the top surface of the base body through a conductive bonding material. A step of superimposing the opening of the lid on the opening of the base, and heat-melting the first sealing material and the second sealing material to hermetically seal the substrate. .
[0012]
The manufacturing method according to claim 2 is characterized in that, in the above-described manufacturing method, the second sealing material is applied in a state having gaps of the same width at regular intervals.
[0013]
Moreover, in the manufacturing method of Claim 3, in the above-mentioned manufacturing method, the thickness of a 2nd sealing material is apply | coated by the thickness of 1 to 2 times with respect to the thickness of a said 1st sealing material. It is characterized by that.
[0014]
Moreover, in the manufacturing method of Claim 4, in the above-mentioned manufacturing method, the said 1st sealing material and the 2nd sealing material are formed only in the said bank or the one bank part of the said base | substrate. It is characterized by that.
[0015]
Moreover, in Claim 5, it manufactured with the above-mentioned manufacturing method, The piezoelectric vibration device characterized by the above-mentioned.
[0016]
【The invention's effect】
According to claim 1 of the present invention, since the first sealing material is applied to the entire end surface of at least one bank portion of the lid or the base body, there is a region where no sealing material is applied. It is not formed, and there is no possibility of poor airtightness or a decrease in sealing strength due to an insufficient state of the sealing material. Further, since the second sealing material is applied in a state of being isolated from each other at the corners of the end face of the bank portion, the thickness of the entire sealing material does not increase in this region, and the sealing is performed. The sealing material does not protrude due to the excessive state of the material.
[0017]
Moreover, the second sealing material is applied in a state of being isolated from each other at the corners of the end surface of the bank portion, and the surfaces of the sealing material and the second sealing material are hardened first. So, when the lid bank portion is overlapped with the base bank portion, the gap between the corner portion sealing material increases the gas pressure in the lid and base recess until the sealing material melts, When the degassing is surely performed and the sealing material is melted, the second sealing material spreads and spreads on the upper part of the first sealing material made of the same material, and this gap can be reliably closed. For this reason, a hermetic defect is not caused without reducing the sealing strength of the piezoelectric vibration device.
[0018]
Furthermore, the sealing material whose thickness is adjusted in a desired region is applied by a technique such as screen printing by separately applying the first sealing material and one or more second sealing materials. It can be easily created and the thickness of the sealing material can be easily adjusted.
[0019]
According to claim 2 of the present invention, since the second sealing material is applied with a gap having the same width at a constant interval, in addition to the above-described effects, the sealing material A groove having a constant width is formed across the bank portion, and the second sealing material spreads uniformly in the groove portion, and the protrusion of the sealing material is further reduced.
[0020]
Moreover, according to Claim 3 of this invention, since the thickness of the 2nd sealing material is apply | coated 1 to 2 times the thickness with respect to the thickness of the said 1st sealing material, the above-mentioned effect | action In addition to the effect, the degassing before melting the sealing material and the function of closing the gap after melting the sealing material are performed more efficiently. When it is smaller than 1 time, the gas venting efficiency is lowered, and when it is larger than 2 times, the possibility that a gap remains is increased.
[0021]
According to claim 4 of the present invention, the first sealing material and the second sealing material are formed only on the lid or one bank portion of the base body. In addition to the effect, the cost can be reduced without reducing the reliability of sealing.
[0022]
As described above, the manufacturing method of the present invention can eliminate the adverse effect of the characteristics due to the protrusion of the sealing material of the ceramic package without increasing the manufacturing cost, and can suppress the decrease in the sealing strength and the airtightness of the ceramic package. A cheaper and more reliable piezoelectric vibration device can be provided.
[0023]
According to claim 4 of the present invention, since the piezoelectric vibration device is manufactured by the above-described method, the adverse effect of the characteristic due to the protrusion of the sealing material of the ceramic package is eliminated without increasing the manufacturing cost, and A cheaper and more reliable piezoelectric vibration device that can suppress a decrease in sealing strength and airtightness of the ceramic package can be obtained.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
As a piezoelectric vibration device according to the first embodiment of the present invention, a surface-mounted crystal resonator will be described as an example with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a bottom view of the lid of FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. is there.
[0025]
The surface-mount type crystal resonator has a rectangular parallelepiped shape as a whole and has a flat rectangular ceramic base 1 having a concave portion with an open top, and a rectangular crystal diaphragm (piezoelectric vibration element) 3 accommodated in the concave portion of the base. And a rectangular ceramic lid 2 having a concave portion with an opening at the bottom, and a housing space (mounting space) for the piezoelectric vibration element is formed by the concave portion of the ceramic base and the reverse concave portion of the ceramic lid. is doing.
[0026]
The ceramic substrate 1 has a concave shape when viewed in cross section, and has a bank portion 11 and a concave portion 12 that form a square periphery. Inside the concave portion, electrode pads 13 and 14 are formed side by side in the short side direction. (The electrode pad 14 is not shown). These electrode pads are led out to the bottom surface of the ceramic substrate by an extraction electrode (not shown).
[0027]
The ceramic lid 2 has a reverse concave shape when viewed in cross section, and has a bank portion 21 and a recess portion 22 that form a square periphery corresponding to the bank portion 11 of the base body.
[0028]
These ceramic substrate 1 and ceramic lid 2 can be easily produced by a ceramic lamination technique. That is, it can be created by using ceramic green sheets corresponding to various shapes, metallizing the ceramic green sheets, and firing them integrally.
[0029]
A low melting point glass G (sealing material) is formed at the end of the bank portion of the ceramic lid configured as described above by a method such as screen printing. The low melting point glass formed on the bank of the lid is coated with the first low melting point glass G1 on the entire end surface of the bank of the lid, and the upper surface of the first low melting point glass layer has the above-mentioned At the corner portions 23, 24, 25, and 26 of the bank portion, the second low melting point glass G2 on each side is coated and formed with a gap having the same width at a constant interval. Therefore, as shown in FIG. 2, only the first low-melting glass is applied to the corner portion of the bank portion, and a thin step region (crossing the bank portion) that crosses the bank portion is partially applied to the low-melting glass. Since a groove having a constant width is formed, the second low-melting-point glass spreads uniformly in the gap when melted by sealing, which will be described later, and the protrusion of the sealing material is further reduced. At this time, the thickness of the second low-melting glass applied is set to 1 to 2 times the thickness of the first low-melting glass applied. The function of closing the gap after the previous degassing and melting of the sealing material is performed more efficiently. In this state, the surfaces of the first low melting point glass and the second low melting point glass are cured by heating at a temperature lower than the melting point of the applied low melting point glass and drying. (First step)
A rectangular crystal diaphragm 3 is mounted on the electrode pads 13 and 14 of the base body in a state of floating from the upper surface of the base body with the conductive bonding material S interposed therebetween, and one end in the long side direction is cantilevered. Yes. Although not shown, a pair of excitation electrodes are formed on the front and back surfaces of the quartz crystal plate 3, drawn out to the electrode pads 13 and 14, respectively, and conductively bonded by the conductive bonding material S. (Second step)
The ceramic lid bank portion 21 is mounted on the ceramic base bank 11 with a load, and charged in a heating furnace for a predetermined time in a state filled with an inert gas (for example, a temperature of 320 to 350 ° C.). The low-melting glass G1 and G2 are melted and then cooled to room temperature to cure the low-melting glass and hermetically seal. In consideration of mass productivity, it is preferable to prepare a large number of such ceramic substrate / ceramic lid pairs and put them in a heat curing furnace for a predetermined time to cure the low melting point glass. (Third step)
In the first embodiment, before the hermetic sealing process (after the second process), an annealing process is performed on the ceramic substrate 1 on which the crystal diaphragm 3 is mounted, and then It has shifted to the hermetic sealing step (third step). For this reason, the stress of the conductive bonding material for electrically and mechanically connecting the crystal diaphragm can be reduced, and a more reliable piezoelectric vibration device can be provided.
[0030]
As described above, the surface-mounted crystal resonator is completed.
[0031]
In the first embodiment, the low melting point glass (sealing material) is formed only on the bank portion of the lid, but the same low melting point glass (sealing material) may be formed only on the bank portion of the base. The same low melting point glass (sealing material) may be formed on both the bank portion of the lid and the bank portion of the base. Furthermore, in the said embodiment, although both the 1st low melting glass layer and the 2nd low melting glass layer are comprised by the single layer, you may comprise at least one from the low melting glass of 2 or more layers. .
[0032]
Next, a piezoelectric vibration device according to a second embodiment of the present invention will be described with reference to the drawings by taking a surface-mounted crystal resonator as an example. FIG. 4 is a bottom view of a lid showing a second embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line BB of FIG. In addition, about the part similar to the said embodiment, the same number was attached | subjected and some description was omitted.
[0033]
Low melting point glass (sealing material) is formed at the ends of the embankments of the ceramic lid 1 and the ceramic base 2 by a technique such as screen printing. In the low melting point glass formed on the bank and the bank portion of the base, the first low melting point glass G1 is applied to the entire end surfaces of the lid and the base bank (the base is not shown). On the upper surface of the first low melting point glass layer of the lid, the corners 23, 24, 25, 26 of the bank part and the central parts 27, 28 in the long side direction of the bank part are provided on the second side of each side. The low melting point glass G2 is applied and formed in a state of being isolated from each other. For this reason, as shown in FIG. 4, only the first low melting point glass is applied to the corner portion of the bank portion and the central portion in the long side direction, and a portion of the low melting point glass has a small thickness across the bank portion. A stepped region is formed, and not only the corner portion of the bank portion but also the central portion in the long side direction is controlled to prevent the low melting point glass from protruding and to improve the outgassing property. At this time, the thickness of the second low-melting glass applied is set to 1 to 2 times the thickness of the first low-melting glass applied. The function of closing the gap after the previous degassing and melting of the sealing material is performed more efficiently. In this state, the surfaces of the first low melting point glass and the second low melting point glass are cured by heating at a temperature lower than the melting point of the applied low melting point glass and drying. (First step)
Similarly to the first embodiment, the rectangular crystal diaphragm 3 is mounted on the electrode pads 13 and 14 of the base body in a state of floating from the top surface of the base body via the conductive bonding material S, and has one end in the long side direction. Is configured to be cantilevered. (Second step)
An annealing step is performed on the ceramic substrate 1 on which the crystal diaphragm 3 is mounted. (Third step)
The dam portion 21 of the ceramic lid is mounted on the dam portion 11 of the ceramic substrate, and charged in a heating furnace for a predetermined time in a state filled with an inert gas (for example, at a temperature of 320 to 350 ° C. for about 10 minutes). ), Melting the low-melting glass G1 and G2, and then cooling to room temperature to cure the low-melting glass and hermetically seal. In consideration of mass productivity, it is preferable to prepare a large number of such ceramic substrate / ceramic lid pairs and put them in a heat curing furnace for a predetermined time to cure the low melting point glass. (Fourth process)
In the second embodiment, an annealing process is performed on the hermetically sealed ceramic substrate 1 and the ceramic lid 2 even after the hermetic sealing process (after the fourth process). Yes. For this reason, the characteristic with respect to a time-dependent change of the hermetically sealed piezoelectric vibration device can be improved, and a more reliable piezoelectric vibration device can be provided.
[0034]
As described above, the surface-mounted crystal resonator is completed.
[0035]
In the second embodiment, the first low-melting glass (first sealing material) and the second low-melting glass (second sealing material) are formed on the bank of the lid, and the bank of the base is formed. Since the first low-melting glass (first sealing material) is formed on the lid, the separated second low-melting glass (second sealing material) is melted on both the lid and the substrate. The spread is further promoted by adapting to the formed first low-melting glass, the gap due to the step can be surely closed, and the sealing strength is further improved.
[0036]
The first low melting point glass (first sealing material) and the second low melting point glass (second sealing material) are formed on the bank portion of the base, and the first low melting point glass is formed on the bank portion of the lid. Even if glass (first sealing material) is formed, the same effect can be obtained. Furthermore, in the said embodiment, although both the 1st low melting glass layer and the 2nd low melting glass layer are comprised by the single layer, you may comprise at least one from the low melting glass of 2 or more layers. .
[0037]
In the above embodiment, an example of the low melting point glass is shown as the sealing material, but a metal brazing material such as an epoxy resin adhesive or solder can also be applied. As an example of the ceramic package, the one having the bank portion on both the lid and the base is taken as an example, but the present invention can be applied to only the lid or only the base having the bank portion. As a holding form of the piezoelectric vibration device, a one-end holding structure is taken as an example, but it can also be applied to a both-end holding structure. Furthermore, as an example of a piezoelectric vibration device, an example of a crystal resonator has been shown, but it can be applied to other piezoelectric vibration devices such as a crystal oscillator, a crystal filter, and a SAW filter.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention.
2 is a bottom view of the lid of FIG. 1. FIG.
3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is a bottom view of a lid showing a second embodiment of the present invention.
5 is a cross-sectional view taken along line BB in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ceramic base body 2 Ceramic lid 3 Crystal diaphragm (piezoelectric vibration element)

Claims

It comprises a planar polygonal ceramic base, a piezoelectric vibration element mounted on the base, and a ceramic lid corresponding to the planar shape of the base, and the base and the lid are interposed via a sealing material. A method of manufacturing a piezoelectric vibration device that is bonded and hermetically sealed,
At least one of the lid or the base body is formed with a bank portion and a recess, and a first sealing material is applied to the entire end surface of the bank portion, and an upper portion of the first sealing material is applied. The second sealing material is made of the same material as the first sealing material, and is separated from each other at the corners of the end face of the bank portion. Applied in a state where the surface of the first sealing material and the second sealing material is cured first,
A step in which a piezoelectric diaphragm is mounted on the base body in a state of floating from the top surface of the base body through a conductive bonding material;
A piezoelectric vibration device comprising a step of hermetically sealing the opening of the lid with the opening of the base and heating and melting the first sealing material and the second sealing material. Manufacturing method.

2. The method of manufacturing a piezoelectric vibration device according to claim 1, wherein the second sealing material is applied with a gap having the same width at a constant interval.

The thickness of the 2nd sealing material is apply | coated 1 to 2 times the thickness with respect to the thickness of the said 1st sealing material, The claim 1 characterized by the above-mentioned A method for manufacturing a piezoelectric vibration device.

The said 1st sealing material and the 2nd sealing material are formed only in the said lid | cover or one bank part of the said base | substrate, The Claim 1 characterized by the above-mentioned. A method for manufacturing a piezoelectric vibration device.

A piezoelectric vibration device manufactured by the method for manufacturing a piezoelectric vibration device according to any one of claims 1 to 4.