JP2004179361A

JP2004179361A - Covering member and container for housing electronic components using the same

Info

Publication number: JP2004179361A
Application number: JP2002343336A
Authority: JP
Inventors: Sadakatsu Yoshida; 定功吉田
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-11-27
Filing date: 2002-11-27
Publication date: 2004-06-24
Anticipated expiration: 2022-11-27
Also published as: JP4044832B2

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that, when a thermal hysteresis of 230-240°C is added during mounting of electronic components, a packaging material is melted and airtightness inside an electronic device cannot be ensured. <P>SOLUTION: A covering member 1 is formed of a cover 2 and a packaging material 3 stuck to the surface thereof. The packaging material 3 has a double-layer structure wherein a first layer 3a, a second layer 3b are arranged in order from the side of the cover 2, the second layer 3b is formed of solder made mainly of tin, and the first layer 3a is formed of metal made mainly of metal constituting an alloy with a melting point of 250°C or higher together with the solder of the second layer 3b. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、半導体素子や圧電振動子等の電子部品を気密に封止して収納するための蓋部材およびこれを用いた電子部品収納用容器に関し、特に封止材に低融点合金を用いて封止を行なう蓋部材およびこれを用いた電子部品収納用容器に関する。
【０００２】
【従来の技術】
従来、半導体素子等の電子部品を収容するための電子部品収納用容器は、例えば酸化アルミニウム質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電子部品を収容するための凹部およびその周辺から下面にかけて導出したタングステンやモリブデン等の高融点金属から成る複数個のメタライズ配線層を有し、上面の外周部に封止用のメタライズ金属層が被着された絶縁基体と、金属材料から成り、下面の外周部に封止材が被着されている蓋体とから構成されている。そして、絶縁基体の凹部底面に半導体素子等の電子部品を接着剤を介して接着するとともに電子部品の各電極をボンディングワイヤ等を介してメタライズ配線層に接続し、しかる後、絶縁基体のメタライズ金属層に、蓋体をその下面に被着させておいた封止材が相対するように位置合わせを行ない、窒素雰囲気等の不活性雰囲気中でメタライズ金属層と封止材とを溶融一体化させ、絶縁基体と蓋体とから成る容器を気密に封止することによって最終製品としての電子装置となる。
なお、このような従来の電子装置においては、絶縁基体と蓋体とを接合する封止材として、鉛を主成分とする半田が使用されていた。
【０００３】
しかしながら、封止材に含有される鉛が環境汚染物質に指定され、例えば、鉛を含有する半田を使用した電子装置が屋外に廃棄もしくは放置され風雨に曝された場合、環境中に鉛が溶け出し環境を汚染する危険性があり、近年、地球環境保護運動の高まりの中で鉛を含有しない封止材が要求されるようになってきた。
【０００４】
そこで、人体に対して有害である鉛を用いない各種封止材が開発・提案されてきた。このような封止材として、例えば錫やビスマス−銀、亜鉛−アルミニウム等を主成分とする各種半田が採用されている。
【０００５】
【特許文献１】
特開２０００−３０７２２８号公報
【０００６】
【発明が解決しようとする課題】
しかしながら錫や銀・亜鉛を含有した合金から成る半田は、温度が−５５〜１２５℃の温度サイクル条件下での耐熱疲労性には優れた信頼性を示すものの、これらの半田は、その融点がいずれも２２５℃以下であり、この半田を絶縁基体と蓋体とを気密に封止する封止材として使用した場合、封止材に電子装置を外部電気回路等に実装する際の２３０〜２４０℃の熱履歴が加わり封止材自体が溶融してしまい、電子装置内部の気密封止が破れてしまうという問題点を有していた。
【０００７】
また、ビスマス−銀を主成分とする半田は、−５５〜１２５℃の温度サイクル条件下での耐熱疲労特性に劣り気密信頼性に欠けるため、電子装置の気密封止用に用いるには不適当であるという課題を有していた。
【０００８】
さらに、亜鉛−アルミニウムを主成分とする半田は、空気中に放置した場合に、腐食が進行しやすく長期の気密信頼性に欠け、電子装置の気密封止用に用いるには、これもまた不適当であるという課題を有していた。
【０００９】
本発明は、このような従来の問題点に鑑み完成されたもので、その目的は、電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わっても電子装置の気密性が確保でき、封止材自体の耐食性にも優れ、さらに、鉛を含有しない地球環境に優しい蓋部材およびこれを用いた電子部品収納用容器を提供することにある。
【００１０】
【課題を解決するための手段】
本発明の蓋部材は、蓋体と、この蓋体の表面に被着形成された封止材とから成る蓋部材であって、前記封止材は、前記蓋体側から順に配置された第１層および第２層から成る２層構造を有しており、前記第２層を錫を主成分とする半田で形成し、前記第１層を前記第２層の半田と共に融点が２５０℃以上の合金を形成する金属を主成分とする金属で形成したことを特徴とするものである。
【００１１】
本発明の蓋部材によれば、封止材の第２層を錫を主成分とする半田で形成し、第１層を第２層の半田と共に融点が２５０℃以上の合金を形成する金属を主成分とする金属で形成したことから、この蓋部材と封止面に枠状のメタライズ金属層を有する絶縁基体とを用いて電子部品収納用容器を製作した場合、封止材の第２層は、その融点が２２５℃以下と低く封止工程で良好な流動性を示し、封止工程中の温度の上昇による容器内部の圧力増加および一定圧力の封止荷重によって容器の外側に押し出されて蓋体の周囲にフィレットを良好に形成し、その結果、容器の気密封止を良好なものとすることができ、温度サイクル等の耐熱疲労試験においても気密信頼性の高い電子部品収納用容器を得ることができる。また、封止工程の熱履歴により封止材の第２層が容器の外側に押し出されるために、絶縁基体のメタライズ金属層と蓋体とが第１層の金属と第２層の半田とから成る、融点が２５０℃以上の合金をを介して接合されることとなるので、その結果、封止材に電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わったとしても、封止材が溶融して容器内部の気密封止が破れてしまうことはない。
【００１２】
また、本発明の蓋部材は、上記構成において、前記第１層を銀または銀−銅合金で、前記第２層を錫−銀半田または錫−銀−銅半田で形成したことを特徴とするものである。
【００１３】
本発明の蓋部材によれば、上記構成において、封止材の第１層を銀または銀−銅合金で、第２層を錫−銀半田または錫−銀−銅半田で形成した場合には、第１層の銀が第２層の半田の主成分である錫と容易に反応して固層線温度が２５０℃以上の合金層を良好に形成し、より気密信頼性の高い電子部品収納用容器を得ることができる。
【００１４】
本発明の電子部品収納用容器は、上面に電子部品が搭載される搭載部およびこの搭載部を取り囲む枠状のメタライズ金属層を有する絶縁基体と、上記構成の蓋部材とから成り、前記枠状のメタライズ金属層に、前記封止材を介して前記蓋体を接合させ、前記絶縁基体と前記蓋体とで構成される容器の内部に電子部品を気密に収容することを特徴とするものである。
【００１５】
本発明の電子部品収納用容器によれば、絶縁基体のメタライズ金属層と蓋体とが第１層の金属と第２層の半田とから成る、融点が２５０℃以上の合金をを介して接合されることとなるので、その結果、封止材に電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わったとしても、封止材が溶融して容器内部の気密封止が破れてしまうことはなく、気密信頼性の高い電子部品収納用容器とすることができる。
【００１６】
【発明の実施の形態】
次に、本発明の蓋部材および電子部品収納用容器を添付の図面に基づいて詳細に説明する。
図１は、本発明の蓋部材の実施の形態の一例を示す断面図、図２はその要部拡大断面図であり、これらの図において２は蓋体、３は封止材、３ａは封止材の第１層、３ｂは封止材の第２層であり、主にこれらで本発明の蓋部材１が構成されている。
【００１７】
蓋部材１を構成する蓋体２は、例えば４２アロイや鉄・ニッケル・コバルト合金等の金属、あるいは酸化アルミニウムやムライト・窒化アルミニウム・炭化珪素・ガラスセラミックス等を主成分とする焼結体等のセラミックスから成り、蓋体２が金属から成る場合は、蓋体２と成る母材を蓋体２に対応した形状を有する打抜き金型で打抜くことによって製作され、また、蓋体２がセラミックス、例えば酸化アルミニウム質焼結体から成る場合は、先ず、アルミナ（Ａｌ_２Ｏ_３）やシリカ（ＳｉＯ_２）・カルシア（ＣａＯ）・マグネシア（ＭｇＯ）等の原料粉末に適当な有機溶剤・溶媒を添加混合して泥漿状と成し、これ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を採用してシート状に成形しセラミックグリーンシートを得、その後、セラミックグリーンシートを所定形状に打ち抜き加工するとともに複数枚積層し、約１６００℃の温度で焼成することにより製作される。
【００１８】
なお、封止材３が被着される領域には、各種金属によるメタライズ層やめっき層が形成されている。なお、蓋体２が金属から成る場合においても、封止材３が被着される領域に各種金属によるメタライズ層やめっき層を形成してもよい。
【００１９】
そして本発明の蓋部材１においては、封止材３は蓋体２側から順に配置された第１層３ａおよび第２層３ｂから成る２層構造を有しており、第２層３ｂが錫を主成分とする半田で形成され、第１層３ａが第２層３ｂの半田と共に融点が２５０℃以上の合金を形成する金属を主成分とする金属で形成されている。また、本発明においてはこのことが重要である。
【００２０】
本発明の蓋部材１によれば、封止材３の第２層３ｂを錫を主成分とする半田で形成し、第１層３ａを第２層３ｂの半田と共に融点が２５０℃以上の合金を形成する金属を主成分とする金属で形成したことから、この蓋部材１と封止面に枠状のメタライズ金属層を有する絶縁基体とを用いて電子部品収納用容器を製作した場合、封止材３の第２層３ｂは、その融点が２２５℃以下と低く封止工程で良好な流動性を示し、封止工程中の温度の上昇による容器内部の圧力増加および一定圧力の封止荷重によって容器の外側に押し出されて蓋体２の周囲にフィレットを良好に形成し、その結果、容器の気密封止を良好なものとすることができ、温度サイクル等の耐熱疲労試験においても気密信頼性の高い電子部品収納用容器を得ることができる。また、封止工程の熱履歴により封止材３の第２層３ｂが容器の外側に押し出されるために、絶縁基体のメタライズ金属層と蓋体２とが第１層３ａの金属と第２層３ｂの半田とから成る、融点が２５０℃以上の合金をを介して接合されることとなるので、その結果、封止材３に電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わったとしても、封止材３が溶融して容器内部の気密封止が破れてしまうことはない。
【００２１】
また、このような封止材３の第１層３ａを銀または銀−銅合金で、第２層３ｂを錫−銀または錫−銀−銅半田で形成することが好ましい。
本発明の蓋部材１によれば、封止材３の第１層３ａを銀または銀−銅合金で、第２層３ｂを錫−銀または錫−銀−銅半田で形成した場合には、封止材３の第１層３ａの銀が第２層３ｂの半田の主成分である錫と容易に反応して固層線温度が２５０℃以上の合金層領域３ｃを形成し、より気密信頼性の高い電子部品収納用容器４を得ることができる。
【００２２】
このような第１層３ａに用いる銀または銀を主成分とする合金としては、例えば、７２質量％の銀と２８質量％の銅とから成る共晶銀ろうや、６０質量％の銀と３０質量％の銅と１０質量％の錫とから成る合金、その他各種銀合金が用いられる。
【００２３】
また、第２層３ｂに用いられる錫を主成分とする半田としては、例えば、９６．５質量％の錫と３．５質量％の銀とから成る共晶や、９５．７５質量％の錫と３．５質量％の銀と０．７５質量％の銅とから成る共晶、あるいは９２質量％の錫と８質量％の亜鉛、９９．３質量％の錫と０．７質量％の銅とから成る共晶、あるいは共晶に近い組成で鉛を含有しない各種半田が用いられる。なお、このような錫を主成分とする半田としては、電子部品の熱的保護や残留応力の観点からは、できる限り低温で溶融可能なものが好ましく、例えば、９６．５質量％の錫と３．５質量％の銀とから成る共晶は、その溶融温度が約２２１℃であり、耐熱性に優れた合金を良好に形成することから、好適に用いられる。
【００２４】
また、封止材３の第１層３ａの厚みは１〜１００μｍが好ましく、１μｍ未満では封止時の熱履歴により第１層３ａの金属が第２層３ｂの半田に食われてしまい耐熱性が劣化する傾向があり、厚みが１００μｍを超えると、蓋体２との熱膨張差によって、蓋体２に反りが発生しやすくなり、気密封止性が不完全となる傾向がある。従って、第１層３ａの厚みは、１〜１００μｍが好ましい。
【００２５】
さらに、封止材３の第２層３ｂの厚みは１０〜１００μｍが好ましく、１０μｍ未満では気密封止性が不完全と成る傾向があり、１００μｍを超えると封止時に、半田が外側に溢れ出し、製品の外観を損なう傾向がある。従って、第２層３ｂの厚みは１０〜１００μｍが好ましい。
【００２６】
このような封止材３は次に述べる方法により、蓋体２に被着される。まず、銀もしくは銀−銅合金の粉末に有機溶剤・溶媒を添加混合して得た金属ペーストを蓋体２に、厚みが１〜１００μｍとなるようにスクリーン印刷する方法、あるいは銀もしくは銀−銅合金から成る、厚みが１〜１００μｍのフィルムやシートを打ち抜き、還元ガス中、温度８５０℃で基体１に溶融密着させる方法等の方法により第１層３ａを形成する。次に、第１層３ａの上に、めっきにより錫を主成分とする半田を生成させる方法により第２層３ｂを形成する。
【００２７】
あるいは他の方法として、蓋体２の材料リボンに、予め適切な厚みにした銀−銅合金リボン、錫主成分の半田リボンを重ねあわせ、全体を加圧圧延することにより得られた３層金属を蓋体２の形状に金型で打ち抜くことにより蓋部材１が得られ、これにより第１層３ａの厚みが１〜１００μｍ、第２層３ｂの厚みが１０〜１００μｍの封止材３が蓋部材１表面に形成される。
【００２８】
かくして本発明の蓋部材１によれば、封止材３の第２層３ｂを錫を主成分とする半田で形成し、第１層３ａを第２層３ｂの半田と共に融点が２５０℃以上の合金を形成する金属を主成分とする金属で形成したことから、この蓋部材１と封止面に枠状のメタライズ金属層を有する絶縁基体とを用いて電子部品収納用容器を製作した場合、封止材３の第２層３ｂは、その融点が２２５℃以下と低く封止工程で良好な流動性を示し、封止工程中の温度の上昇による容器内部の圧力増加および一定圧力の封止荷重によって容器の外側に押し出されて蓋体の周囲にフィレットを良好に形成し、その結果、容器の気密封止を良好なものとすることができ、温度サイクル等の耐熱疲労試験においても気密信頼性の高い電子部品収納用容器を得ることができる。また、封止工程の熱履歴により封止材３の第２層３ｂが容器の外側に押し出されるために、絶縁基体のメタライズ金属層と蓋体２とが第１層３ａの金属と第２層３ｂの半田とから成る、融点が２５０℃以上の合金をを介して接合されることとなるので、その結果、封止材３に電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わったとしても、封止材３が溶融して容器内部の気密封止が破れてしまうことはない。
【００２９】
次に、本発明の蓋部材１を用いた電子部品収納用容器について、図３および図４に基づいて詳細に説明する。
【００３０】
図３は、本発明の電子部品収納用容器の実施の形態の一例を示す断面図、図４はその要部拡大断面図であり、これらの図において、４は電子部品収納用容器、５は絶縁基体である。なお、図３には、電子部品収納用容器に電子部品６を実装して電子装置とした例を示している。
【００３１】
絶縁基体５は、その上面中央部に電子部品６を収容するための凹部が設けられており、この凹部の底面には電子部品６がガラスや樹脂・ろう材等の接着剤を介して接着固定される。
【００３２】
また、絶縁基体５凹部の底面より外周部にかけて、複数のメタライズ配線層（図示せず）が被着形成されており、このメタライズ配線層の凹部の底面に位置する部位には電子部品６の各電極がボンディングワイヤ８を介して電気的に接続され、外部に導出する部位は外部電気回路基板の配線導体（図示せず）に導電性接続部材を介して電気的に接続される。
【００３３】
さらに、絶縁基体５の上面の凹部外周部には、本発明の蓋部材１との接合用の枠状のメタライズ金属層７が被着されている。
絶縁基体５は、酸化アルミニウムやムライト・窒化アルミニウム・炭化珪素・ガラスセラミックス等を主成分とする焼結体等の電気絶縁材料から成り、例えば、酸化アルミニウム質焼結体から成る場合であれば、先ずアルミナ（Ａｌ_２Ｏ_３）やシリカ（ＳｉＯ_２）・カルシア（ＣａＯ）・マグネシア（ＭｇＯ）等の原料粉末に適当な有機溶剤・溶媒を添加混合して泥漿状と成し、これ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を採用してシート状に成形しセラミックグリーンシートを得、その後、セラミックグリーンシートを所定形状に打ち抜き加工するとともに複数枚積層し、約１６００℃の温度で焼成することにより製作される。
【００３４】
また、メタライズ配線層および枠状のメタライズ金属層７は、タングステンやモリブデン・マンガン等の高融点金属から成り、これらの粉末に有機溶剤・溶媒を添加混合した金属ペーストをそれぞれセラミックグリーンシートの所定位置に従来周知のスクリーン印刷法により所定パターンに被着形成させておき、セラミックグリーンシートと同時に焼成することにより形成される。なお、枠状のメタライズ金属層７には、その表面に耐食性に優れ、半田等のろう材との濡れ性の良好な金等の貴金属をめっき法等により、０．１〜１μｍの厚さに被着させておくと、フラックスを用いることなく蓋体２と接合することが可能となる。
【００３５】
なお、フラックスは電子部品収納用容器４の内部に飛散すると、電子部品６の電極を腐蝕し断線を発生させる原因となることから、枠状のメタライズ金属層７の表面には、金等の貴金属をめっき法等により被着させておき、メタライズ金属層７と蓋部材１との接合をフラックスを用いず行なうことが好ましい。
【００３６】
そして、絶縁基体５の上面の凹部外周部に形成されたメタライズ金属層７に、蓋部材１がその下面に被着形成された金属から成る封止材３を介して接合される。
また、絶縁基体５と蓋部材２との接合は、絶縁基体５の枠状のメタライズ金属層７と蓋体２との間に封止材３が挟まるように蓋部材１を絶縁基体５上に載置し、しかる後、蓋体２を絶縁基体５側に一定圧力で押圧しながらピーク温度が約２６０〜３００℃の温度で窒素雰囲気のシール炉に０．５〜１０分間保持して封止材３を溶融させることにより、封止材３の第２層３ｂの半田が外側に流れ出しフィレットを形成するとともに、第１層３ａと第２層３ｂとの間に合金層３ｃが絶縁基体５のメタライズ金属層７側に成長し、絶縁基体５の上面に蓋体２が封止材３の第１層３ａと第２層３ｂとを介して気密に接合されることとなる。
【００３７】
なお、合金層３ｃの合金は、電子装置を外部電気回路等に実装する際の２３０〜２４０℃の加熱温度を超える固相線温度を有することが必要である。それにより封止材３が電子装置を外部電気回路に実装する際の加熱温度に曝されても、第１層３ａの金属と錫を主成分とする第２層３ｂの半田間に形成された合金層３ｃで形状を保ち、外周部に錫を主成分とする第２層３ｂが存在することになる。従って、たとえ錫を主成分とした第２層３ｂが溶融したとしても、合金層３ｃによって、溶融した第２層３ｂが保持されて容器の気密性が損なわれることはない。
【００３８】
かくして本発明の蓋部材１およびこれを用いた電子部品収納用容器４によれば、絶縁基体５の凹部底面に半導体素子等の電子部品６を接着剤等を介して接着するとともに電子部品６の各電極をボンディングワイヤ８等を介してメタライズ配線層に接続し、しかる後、絶縁基体５と相対向する蓋体２の主面に被着させておいた封止材３を加熱・溶融させ、絶縁基体５と蓋体２とから成る容器を封止することによって最終製品としての電子装置となる。
【００３９】
なお、本発明は上記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、上述の実施例では電子部品として半導体素子を例に挙げ、これを収容した電子装置について詳述したが、圧電振動子や弾性表面波素子等の電子部品を収容した電子装置にも適用可能である。また、図４では、封止材が第１層、合金層および第２層の３層構造から成る例を示したが、封止材が第１層がすべて合金層となり、合金層および第２層から成る２層構造となってもよい。さらに、上述の実施例では、蓋体を平板状とし、絶縁基体を上面中央部に凹部を有する形状として説明したが、蓋体を、例えば絶縁基体と対向する面に凹部を有する形状とし、絶縁基体を平板状の形状としてもよいことはもちろんである。
【００４０】
【発明の効果】
本発明の蓋部材によれば、封止材の第２層を錫を主成分とする半田で形成し、第１層を第２層の半田と共に融点が２５０℃以上の合金を形成する金属を主成分とする金属で形成したことから、この蓋部材と封止面に枠状のメタライズ金属層を有する絶縁基体とを用いて電子部品収納用容器を製作した場合、封止材の第２層は、その融点が２２５℃以下と低く封止工程で良好な流動性を示し、封止工程中の温度の上昇による容器内部の圧力増加および一定圧力の封止荷重によって容器の外側に押し出されて蓋体の周囲にフィレットを良好に形成し、その結果、容器の気密封止を良好なものとすることができ、温度サイクル等の耐熱疲労試験においても気密信頼性の高い電子部品収納用容器を得ることができる。また、封止工程の熱履歴により封止材の第２層が容器の外側に押し出されるために、絶縁基体のメタライズ金属層と蓋体とが第１層の金属と第２層の半田とから成る、融点が２５０℃以上の合金をを介して接合されることとなるので、その結果、封止材に電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わったとしても、封止材が溶融して容器内部の気密封止が破れてしまうことはない。
【００４１】
また、本発明の蓋部材によれば、封止材の第１層を銀または銀−銅合金で、第２層を錫−銀半田または錫−銀−銅半田で形成した場合には、第１層の銀が第２層の半田の主成分である錫と容易に反応して固層線温度が２５０℃以上の合金層を良好に形成し、より気密信頼性の高い電子部品収納用容器を得ることができる。
【００４２】
本発明の電子部品収納用容器によれば、絶縁基体のメタライズ金属層と蓋体とが第１層の金属と第２層の半田とから成る、融点が２５０℃以上の合金をを介して接合されることとなるので、その結果、封止材に電子装置を外部電気回路等に実装する際に２３０〜２４０℃の熱履歴が加わったとしても、封止材が溶融して容器内部の気密封止が破れてしまうことはなく、気密信頼性の高い電子部品収納用容器とすることができる。
【図面の簡単な説明】
【図１】本発明の蓋部材の実施の形態の一例を示す断面図である。
【図２】図１の要部拡大断面図である。
【図３】本発明の電子部品収納用容器の実施の形態の一例を示す断面図である。
【図４】図３の要部拡大断面図である。
【符号の説明】
１・・・・・・・蓋部材
２・・・・・・・蓋体
３・・・・・・・封止材
３ａ・・・・・・第１層
３ｂ・・・・・・第２層
３ｃ・・・・・・合金層
４・・・・・・・電子部品収納用容器
５・・・・・・・絶縁基体
６・・・・・・・電子部品
７・・・・・・・メタライズ金属層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lid member for hermetically sealing and housing electronic components such as a semiconductor element and a piezoelectric vibrator and an electronic component housing container using the same. The present invention relates to a lid member for performing sealing and an electronic component storage container using the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electronic component storage container for storing an electronic component such as a semiconductor element is made of an electrically insulating material such as an aluminum oxide sintered body, and a concave portion for storing the electronic component is provided at a substantially central portion of an upper surface thereof. An insulating base having a plurality of metallized wiring layers made of a refractory metal such as tungsten or molybdenum derived from the periphery to the lower surface, and a metallized metal layer for sealing applied to the outer peripheral portion of the upper surface; And a lid having a sealing material attached to the outer peripheral portion of the lower surface. Then, an electronic component such as a semiconductor element is bonded to the bottom surface of the concave portion of the insulating base via an adhesive, and each electrode of the electronic component is connected to a metallized wiring layer via a bonding wire or the like. The layer is positioned so that the sealing material having the lid attached to the lower surface thereof faces each other, and the metallized metal layer and the sealing material are fused and integrated in an inert atmosphere such as a nitrogen atmosphere. An electronic device as a final product is obtained by hermetically sealing a container including an insulating base and a lid.
In such a conventional electronic device, a solder containing lead as a main component has been used as a sealing material for joining the insulating base and the lid.
[0003]
However, lead contained in the encapsulant is designated as an environmental pollutant.For example, when an electronic device using solder containing lead is discarded or left outdoors and exposed to the weather, lead dissolves in the environment. There is a danger of polluting the dispensing environment, and in recent years, with the rise of the global environmental protection movement, a lead-free sealing material has been required.
[0004]
Therefore, various sealing materials that do not use lead, which is harmful to the human body, have been developed and proposed. As such a sealing material, for example, various solders mainly containing tin, bismuth-silver, zinc-aluminum and the like are employed.
[0005]
[Patent Document 1]
JP 2000-307228 A
[Problems to be solved by the invention]
However, although solder made of an alloy containing tin or silver / zinc exhibits excellent reliability in thermal fatigue resistance under a temperature cycle of −55 to 125 ° C., these solders have melting points. Both are 225 ° C. or less, and when this solder is used as a sealing material for hermetically sealing the insulating base and the lid, 230-240 when the electronic device is mounted on an external electric circuit or the like with the sealing material. There has been a problem that the sealing material itself melts due to the heat history of ° C. and the hermetic sealing inside the electronic device is broken.
[0007]
Further, a solder containing bismuth-silver as a main component is inferior in heat-resistant fatigue characteristics under a temperature cycle condition of -55 to 125 [deg.] C. and lacks hermetic reliability. Had the problem of being
[0008]
Furthermore, the solder containing zinc-aluminum as a main component is susceptible to corrosion when left in the air and lacks long-term hermetic reliability, and is not suitable for hermetic sealing of electronic devices. Had the problem of being appropriate.
[0009]
The present invention has been completed in view of such conventional problems, and has as its object the airtightness of an electronic device even when a heat history of 230 to 240 ° C. is applied when the electronic device is mounted on an external electric circuit or the like. An object of the present invention is to provide a cover member which can ensure the sealing property, is excellent in the corrosion resistance of the sealing material itself, and is free of lead and is environmentally friendly, and a container for storing electronic components using the same.
[0010]
[Means for Solving the Problems]
The lid member of the present invention is a lid member comprising a lid and a sealing material adhered to the surface of the lid, wherein the sealing material is a first member arranged in order from the lid side. Having a two-layer structure consisting of a layer and a second layer, wherein the second layer is formed of a solder containing tin as a main component, and the first layer together with the solder of the second layer has a melting point of 250 ° C. or more. It is characterized by being formed of a metal whose main component is a metal forming an alloy.
[0011]
According to the lid member of the present invention, the second layer of the sealing material is formed of solder containing tin as a main component, and the first layer is formed of a metal which forms an alloy having a melting point of 250 ° C. or more together with the solder of the second layer. When the electronic component storage container is manufactured using this lid member and the insulating base having a frame-shaped metallized metal layer on the sealing surface, the second layer of the sealing material is formed from the metal as the main component. Has a low melting point of 225 ° C. or less and exhibits good fluidity in the sealing step, and is pushed out of the container by a pressure increase inside the container due to a rise in temperature during the sealing step and a sealing load of a constant pressure. A good fillet is formed around the lid, and as a result, the hermetic sealing of the container can be made good. Obtainable. Further, since the second layer of the sealing material is pushed out of the container by the heat history of the sealing step, the metallized metal layer and the lid of the insulating base are separated from the first layer metal and the second layer solder. Is joined via an alloy having a melting point of 250 ° C. or higher, as a result, a heat history of 230 to 240 ° C. is added when the electronic device is mounted on an external electric circuit or the like in the sealing material. Even if the sealing material is not melted, the hermetic sealing inside the container is not broken.
[0012]
In the lid member according to the present invention, the first layer is formed of silver or a silver-copper alloy, and the second layer is formed of tin-silver solder or tin-silver-copper solder. Things.
[0013]
According to the lid member of the present invention, in the above configuration, when the first layer of the sealing material is formed of silver or a silver-copper alloy, and the second layer is formed of tin-silver solder or tin-silver-copper solder The silver of the first layer easily reacts with tin, which is a main component of the solder of the second layer, to form an alloy layer having a solidus temperature of 250 ° C. or higher, and to provide a more airtight and reliable electronic component housing. Container can be obtained.
[0014]
The electronic component storage container of the present invention comprises: a mounting portion on which an electronic component is mounted on an upper surface; an insulating base having a frame-shaped metallized metal layer surrounding the mounting portion; and a lid member having the above configuration. The metallized metal layer is bonded to the lid via the sealing material, and the electronic component is hermetically accommodated in a container formed by the insulating base and the lid. is there.
[0015]
According to the electronic component storage container of the present invention, the metallized metal layer and the lid of the insulating base are joined to each other via an alloy having a melting point of 250 ° C. or more composed of the first layer metal and the second layer solder. As a result, even when a heat history of 230 to 240 ° C. is applied to the mounting of the electronic device on an external electric circuit or the like, the sealing material is melted and the air inside the container is melted. The hermetic seal is not broken, and a highly reliable airtight container for electronic components can be obtained.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the lid member and the electronic component storage container of the present invention will be described in detail with reference to the accompanying drawings.
1 is a cross-sectional view showing an example of an embodiment of a lid member of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part thereof. The first layer 3b of the stopper is the second layer of the sealing material, and these mainly constitute the lid member 1 of the present invention.
[0017]
The cover 2 constituting the cover member 1 is made of, for example, a metal such as 42 alloy or iron / nickel / cobalt alloy, or a sintered body mainly composed of aluminum oxide, mullite, aluminum nitride, silicon carbide, glass ceramic, or the like. When the cover 2 is made of a metal and made of a metal, the cover 2 is manufactured by punching a base material that forms the cover 2 with a punching die having a shape corresponding to the cover 2. For example, in the case of an aluminum oxide sintered body, first, an appropriate organic solvent / solvent is added to a raw material powder such as alumina (Al ₂ O ₃ ), silica (SiO ₂ ), calcia (CaO), magnesia (MgO). The mixture is mixed to form a slurry, which is formed into a sheet by using a conventionally known doctor blade method, calender roll method, or the like to obtain a ceramic green sheet. Thereafter, plural stacked with punching a ceramic green sheet into a predetermined shape, it is manufactured by firing at a temperature of about 1600 ° C..
[0018]
In the region where the sealing material 3 is applied, a metallized layer and a plating layer made of various metals are formed. Note that, even when the lid 2 is made of a metal, a metallized layer or a plating layer made of various metals may be formed in a region where the sealing material 3 is applied.
[0019]
In the lid member 1 of the present invention, the sealing material 3 has a two-layer structure including a first layer 3a and a second layer 3b arranged in order from the lid 2 side, and the second layer 3b is made of tin. The first layer 3a is formed of a metal whose main component is a metal that forms an alloy having a melting point of 250 ° C. or more with the solder of the second layer 3b. This is important in the present invention.
[0020]
According to the lid member 1 of the present invention, the second layer 3b of the sealing material 3 is formed of solder containing tin as a main component, and the first layer 3a is formed of an alloy having a melting point of 250 ° C. or more together with the solder of the second layer 3b. When a container for electronic component storage is manufactured using this lid member 1 and an insulating base having a frame-shaped metallized metal layer on the sealing surface, the sealing is performed. The second layer 3b of the stopper 3 has a low melting point of 225 ° C. or less and exhibits good fluidity in the sealing step, and an increase in pressure inside the container due to an increase in temperature during the sealing step and a sealing load of a constant pressure. Extruded to the outside of the container to form a good fillet around the lid 2, and as a result, the container can be hermetically sealed, and hermetically sealed even in a thermal fatigue test such as a temperature cycle. It is possible to obtain an electronic component storage container having high performance. Further, since the second layer 3b of the sealing material 3 is pushed out of the container by the heat history of the sealing step, the metallized metal layer of the insulating base and the lid 2 are made of the metal of the first layer 3a and the second layer. 3b, the bonding is performed via an alloy having a melting point of 250 ° C. or more, which results in a temperature of 230 to 240 ° C. when the electronic device is mounted on the sealing member 3 in an external electric circuit or the like. Even if the heat history is applied, the sealing material 3 does not melt and the hermetic sealing inside the container is not broken.
[0021]
Further, it is preferable that the first layer 3a of the sealing material 3 is formed of silver or a silver-copper alloy, and the second layer 3b is formed of tin-silver or tin-silver-copper solder.
According to the lid member 1 of the present invention, when the first layer 3a of the sealing material 3 is formed of silver or a silver-copper alloy, and the second layer 3b is formed of tin-silver or tin-silver-copper solder, The silver of the first layer 3a of the sealing material 3 easily reacts with tin which is a main component of the solder of the second layer 3b to form an alloy layer region 3c having a solidus temperature of 250 ° C. or more, and more airtight reliability. It is possible to obtain the electronic component storage container 4 having high performance.
[0022]
Examples of silver or an alloy containing silver as a main component used for the first layer 3a include eutectic silver brazing composed of 72% by mass of silver and 28% by mass of copper, and 60% by mass of silver and 30% by mass of silver. An alloy composed of mass% copper and 10 mass% tin, and various other silver alloys are used.
[0023]
Examples of the solder containing tin as a main component used for the second layer 3b include, for example, a eutectic composed of 96.5% by mass of tin and 3.5% by mass of silver, or a eutectic of 95.75% by mass of tin. Eutectic consisting of 3.5% by weight of silver and 0.75% by weight of copper, or 92% by weight of tin and 8% by weight of zinc, 99.3% by weight of tin and 0.7% by weight of copper Or various solders having a composition close to the eutectic and containing no lead. As the solder containing tin as a main component, a solder that can be melted at a temperature as low as possible is preferable from the viewpoint of thermal protection and residual stress of electronic components. For example, 96.5% by mass of tin is used. Eutectic composed of 3.5% by mass of silver is preferably used because its melting temperature is about 221 ° C. and an alloy excellent in heat resistance is formed satisfactorily.
[0024]
The thickness of the first layer 3a of the sealing material 3 is preferably 1 to 100 μm, and if it is less than 1 μm, the metal of the first layer 3a is eroded by the solder of the second layer 3b due to the heat history at the time of sealing. When the thickness exceeds 100 μm, the lid 2 tends to be warped due to a difference in thermal expansion with the lid 2, and the hermetic sealing property tends to be incomplete. Therefore, the thickness of the first layer 3a is preferably 1 to 100 μm.
[0025]
Furthermore, the thickness of the second layer 3b of the sealing material 3 is preferably 10 to 100 μm, and if it is less than 10 μm, the hermetic sealing tends to be incomplete. If it exceeds 100 μm, the solder overflows during sealing. , Tends to spoil the appearance of the product. Therefore, the thickness of the second layer 3b is preferably 10 to 100 μm.
[0026]
Such a sealing material 3 is attached to the lid 2 by a method described below. First, a metal paste obtained by adding and mixing an organic solvent and a solvent to a powder of silver or a silver-copper alloy is screen-printed on the lid 2 so as to have a thickness of 1 to 100 μm, or silver or silver-copper The first layer 3a is formed by punching out a film or sheet made of an alloy and having a thickness of 1 to 100 μm and melting and adhering to the substrate 1 in a reducing gas at a temperature of 850 ° C. Next, the second layer 3b is formed on the first layer 3a by a method of generating a solder containing tin as a main component by plating.
[0027]
Alternatively, as another method, a three-layer metal obtained by laminating a silver-copper alloy ribbon and a tin-based solder ribbon each having an appropriate thickness in advance on a material ribbon of the lid 2 and pressure-rolling the whole is obtained. Is punched out in the shape of the lid 2 with a mold, whereby the sealing material 3 having a thickness of the first layer 3a of 1 to 100 μm and a thickness of the second layer 3b of 10 to 100 μm is obtained. It is formed on the surface of the member 1.
[0028]
Thus, according to the lid member 1 of the present invention, the second layer 3b of the sealing material 3 is formed of a solder containing tin as a main component, and the first layer 3a together with the solder of the second layer 3b has a melting point of 250 ° C. or more. When the electronic component storage container is manufactured by using the lid member 1 and the insulating base having the frame-shaped metallized metal layer on the sealing surface, the container is made of a metal mainly composed of a metal forming an alloy. The melting point of the second layer 3b of the sealing material 3 is as low as 225 ° C. or less, and the second layer 3b exhibits good fluidity in the sealing step. It is pushed out of the container by the load to form a good fillet around the lid, and as a result, the container can be hermetically sealed well. A highly reliable container for storing electronic components can be obtained. Further, since the second layer 3b of the sealing material 3 is pushed out of the container by the heat history of the sealing step, the metallized metal layer of the insulating base and the lid 2 are made of the metal of the first layer 3a and the second layer. 3b, the bonding is performed via an alloy having a melting point of 250 ° C. or more, which results in a temperature of 230 to 240 ° C. when the electronic device is mounted on the sealing member 3 in an external electric circuit or the like. Even if the heat history is applied, the sealing material 3 does not melt and the hermetic sealing inside the container is not broken.
[0029]
Next, an electronic component storage container using the lid member 1 of the present invention will be described in detail with reference to FIGS.
[0030]
3 is a cross-sectional view showing an example of an embodiment of an electronic component storage container according to the present invention. FIG. 4 is an enlarged cross-sectional view of a main part thereof. It is an insulating base. FIG. 3 shows an example in which the electronic component 6 is mounted on an electronic component storage container to form an electronic device.
[0031]
The insulating base 5 is provided with a concave portion for accommodating the electronic component 6 at the center of the upper surface, and the electronic component 6 is bonded and fixed to the bottom surface of the concave portion via an adhesive such as glass, resin, or brazing material. Is done.
[0032]
A plurality of metallized wiring layers (not shown) are formed on the insulating substrate 5 from the bottom surface to the outer peripheral portion thereof. The electrodes are electrically connected via bonding wires 8, and the portions leading out are electrically connected to wiring conductors (not shown) of the external electric circuit board via conductive connection members.
[0033]
Further, a frame-shaped metallized metal layer 7 for bonding to the lid member 1 of the present invention is attached to the outer periphery of the concave portion on the upper surface of the insulating base 5.
The insulating base 5 is made of an electrically insulating material such as a sintered body mainly composed of aluminum oxide, mullite, aluminum nitride, silicon carbide, glass ceramic, or the like. First, an appropriate organic solvent / solvent is added to a raw material powder such as alumina (Al ₂ O ₃ ), silica (SiO ₂ ), calcia (CaO), magnesia (MgO) and mixed to form a slurry. A ceramic green sheet is obtained by forming into a sheet shape by employing a doctor blade method, a calendar roll method, or the like, and thereafter, a plurality of ceramic green sheets are punched into a predetermined shape and laminated, and fired at a temperature of about 1600 ° C. Produced by
[0034]
The metallized wiring layer and the frame-shaped metallized metal layer 7 are made of a refractory metal such as tungsten or molybdenum / manganese, and a metal paste obtained by adding an organic solvent / solvent to these powders is applied to a predetermined position of the ceramic green sheet. Is formed in a predetermined pattern by a conventionally well-known screen printing method, and is formed by firing simultaneously with the ceramic green sheet. The frame-shaped metallized metal layer 7 is coated with a noble metal such as gold having excellent corrosion resistance on its surface and good wettability with a brazing material such as solder by a plating method or the like to a thickness of 0.1 to 1 μm. If it is adhered, it can be joined to the lid 2 without using flux.
[0035]
When the flux scatters inside the electronic component storage container 4, it causes the electrodes of the electronic component 6 to corrode and cause disconnection. Therefore, the surface of the frame-shaped metallized metal layer 7 is provided with a noble metal such as gold. It is preferable that the metallized metal layer 7 and the cover member 1 are joined without using flux.
[0036]
Then, the lid member 1 is joined to the metallized metal layer 7 formed on the outer periphery of the concave portion on the upper surface of the insulating base 5 via the sealing material 3 made of metal adhered to the lower surface.
The joining of the insulating base 5 and the lid member 2 is performed by placing the lid member 1 on the insulating base 5 such that the sealing material 3 is sandwiched between the frame-shaped metallized metal layer 7 of the insulating base 5 and the lid 2. After mounting, the lid 2 is pressed against the insulating substrate 5 side at a constant pressure, and is sealed at a peak temperature of about 260 to 300 ° C. for 0.5 to 10 minutes in a sealing furnace in a nitrogen atmosphere at a temperature of about 260 to 300 ° C. By melting the material 3, the solder of the second layer 3b of the sealing material 3 flows out to form a fillet, and the alloy layer 3c is formed between the first layer 3a and the second layer 3b. The cover 2 grows on the metallized metal layer 7 side, and is hermetically bonded to the upper surface of the insulating base 5 via the first layer 3a and the second layer 3b of the sealing material 3.
[0037]
Note that the alloy of the alloy layer 3c needs to have a solidus temperature exceeding a heating temperature of 230 to 240 ° C. when the electronic device is mounted on an external electric circuit or the like. Thereby, even when the sealing material 3 is exposed to the heating temperature when the electronic device is mounted on the external electric circuit, the sealing material 3 is formed between the metal of the first layer 3a and the solder of the second layer 3b mainly composed of tin. The shape is maintained by the alloy layer 3c, and the second layer 3b mainly composed of tin is present on the outer peripheral portion. Therefore, even if the second layer 3b mainly containing tin is melted, the airtightness of the container is not impaired by holding the melted second layer 3b by the alloy layer 3c.
[0038]
Thus, according to the lid member 1 of the present invention and the electronic component storage container 4 using the same, the electronic component 6 such as a semiconductor element is bonded to the bottom surface of the concave portion of the insulating base 5 via an adhesive or the like, and Each electrode is connected to a metallized wiring layer via a bonding wire 8 or the like. Thereafter, the sealing material 3 adhered to the main surface of the lid 2 opposed to the insulating substrate 5 is heated and melted. An electronic device as a final product is obtained by sealing a container including the insulating base 5 and the lid 2.
[0039]
The present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention. In the above embodiments, a semiconductor element is taken as an example of an electronic component. Although the electronic device housing this is described in detail, it is also applicable to an electronic device housing electronic components such as a piezoelectric vibrator and a surface acoustic wave element. FIG. 4 shows an example in which the sealing material has a three-layer structure of a first layer, an alloy layer, and a second layer. It may have a two-layer structure composed of layers. Further, in the above-described embodiment, the lid is formed in a flat plate shape, and the insulating base is described as having a concave portion in the center of the upper surface. Needless to say, the substrate may have a flat plate shape.
[0040]
【The invention's effect】
According to the lid member of the present invention, the second layer of the sealing material is formed of solder containing tin as a main component, and the first layer is formed of a metal which forms an alloy having a melting point of 250 ° C. or more together with the solder of the second layer. When the electronic component storage container is manufactured using this lid member and the insulating base having a frame-shaped metallized metal layer on the sealing surface, the second layer of the sealing material is formed from the metal as the main component. Has a low melting point of 225 ° C. or less and exhibits good fluidity in the sealing step, and is pushed out of the container by a pressure increase inside the container due to a rise in temperature during the sealing step and a sealing load of a constant pressure. A good fillet is formed around the lid, and as a result, the hermetic sealing of the container can be made good. Obtainable. Further, since the second layer of the sealing material is pushed out of the container by the heat history of the sealing step, the metallized metal layer and the lid of the insulating base are separated from the first layer metal and the second layer solder. Is joined via an alloy having a melting point of 250 ° C. or higher, as a result, a heat history of 230 to 240 ° C. is added when the electronic device is mounted on an external electric circuit or the like in the sealing material. Even if the sealing material is not melted, the hermetic sealing inside the container is not broken.
[0041]
According to the lid member of the present invention, when the first layer of the sealing material is formed of silver or a silver-copper alloy, and the second layer is formed of tin-silver solder or tin-silver-copper solder, One layer of silver easily reacts with tin, which is a main component of the second layer solder, to form an alloy layer having a solidus temperature of 250 ° C. or more, and a more airtight and reliable electronic component storage container. Can be obtained.
[0042]
According to the electronic component storage container of the present invention, the metallized metal layer and the lid of the insulating base are joined to each other via an alloy having a melting point of 250 ° C. or more composed of the first layer metal and the second layer solder. As a result, even when a heat history of 230 to 240 ° C. is applied to the mounting of the electronic device on an external electric circuit or the like, the sealing material is melted and the air inside the container is melted. The hermetic seal is not broken, and a highly reliable airtight container for electronic components can be obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of a lid member of the present invention.
FIG. 2 is an enlarged sectional view of a main part of FIG.
FIG. 3 is a cross-sectional view illustrating an example of an embodiment of an electronic component storage container according to the present invention.
FIG. 4 is an enlarged sectional view of a main part of FIG. 3;
[Explanation of symbols]
1 lid member 2 lid 3 sealing material 3a first layer 3b second Layer 3c Alloy layer 4 Container 5 for electronic component storage Insulating base 6 Electronic component 7・ Metalized metal layer

Claims

A lid member including a lid and a sealing material adhered to a surface of the lid, wherein the sealing material includes a first layer and a second layer sequentially arranged from the lid side. It has a two-layer structure, in which the second layer is formed of solder containing tin as a main component, and the first layer is mainly formed of a metal which forms an alloy having a melting point of 250 ° C. or more together with the solder of the second layer. A lid member formed of a metal as a component.

The lid member according to claim 1, wherein the first layer is formed of silver or a silver-copper alloy, and the second layer is formed of tin-silver solder or tin-silver-copper solder.

3. The frame-shaped metallized metal layer, comprising: a mounting portion on which an electronic component is mounted on an upper surface; an insulating base having a frame-shaped metallized metal layer surrounding the mounting portion; and the lid member according to claim 1 or 2. An electronic component storage container, wherein the electronic component is hermetically accommodated in a container formed by the insulating base and the lid by bonding the lid to the container via the sealing material.