JP4265319B2

JP4265319B2 - Chip-type surge absorber and manufacturing method thereof

Info

Publication number: JP4265319B2
Application number: JP2003198045A
Authority: JP
Inventors: 康弘社藤; 卓栗原; 剛尾木; 稔晃植田; 美紀足立; 成圭李
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-07-16
Filing date: 2003-07-16
Publication date: 2009-05-20
Anticipated expiration: 2023-07-16
Also published as: JP2005038648A

Description

【０００１】
【発明の属する技術分野】
本発明は、サージから様々な機器を保護し、事故を未然に防ぐのに使用するチップ型サージアブソーバ及びその製造方法に関する。
【０００２】
【従来の技術】
電話機、ファクシミリ、モデム等の通信機器用の電子機器が通信線との接続する部分、電源線、アンテナ或いはＣＲＴ駆動回路等、雷サージや静電気等の異常電圧（サージ電圧）による電撃を受けやすい部分には、異常電圧によって電子機器やこの機器を搭載するプリント基板の熱的損傷又は発火等による破壊を防止するために、サージアブソーバが接続されている。
【０００３】
従来、例えばマイクロギャップを有するサージ吸収素子を用いたサージアブソーバが提案されている。このサージアブソーバは、導電性被膜で被覆した円柱状セラミックス部材の周面に、いわゆるマイクロギャップが形成され、セラミックス部材の両端に一対のキャップ電極を有するサージ吸収素子が不活性ガスと共にガラス管内に収容され、円筒状のガラス管の両端にリード線を有する封止電極が高温加熱で封着された放電型サージアブソーバである（例えば、特許文献１、２参照。）。
【０００４】
一方、円柱状セラミックス部材の熱膨張分を吸収してガラス管のクラック発生を防ぐために、緩衝部材を端子電極と円柱状セラミックス部材との間に挟む技術が提案されている（例えば、特許文献３参照）。
近年、このような放電タイプのサージアブソーバにおいても、表面実装化が進んでいる。上記サージアブソーバに適用した例としては、面実装型（メルフ型）として、封止電極にリード線がなく、実装するときは封止電極と基板側とを半田付けで接続して固定するものがある。
【０００５】
【特許文献１】
特開２００２−１１０３１１号公報（第１図）
【特許文献２】
特公平７−２４２３４号公報（第３図Ａ）
【特許文献３】
特開２０００−１３８０８９号公報（第１図）
【０００６】
【発明が解決しようとする課題】
しかしながら、特許文献２に見られるような上記従来のサージアブソーバには、以下の課題が残されている。すなわち、従来のサージアブソーバを面実装した場合、リード線で取り付けられる場合と異なりサージアブソーバが実装基板に密着するため、温度変化試験または温度変化の繰り返し試験による実装基板とサージアブソーバとの熱膨張差が原因となり、サージアブソーバ内部の円柱状セラミックス部材に応力によるクラックが入るおそれがあった。このため、放電開始電圧が上昇し、アブソーバとしての性能を十分に発揮させることができなかった。また、上記従来の緩衝部材を利用したサージアブソーバの場合、応力緩和が可能でも円柱状セラミックス部材が中心軸から位置ずれするおそれがあった。
本発明は、前述の課題に鑑みてなされたもので、面実装した場合でも熱応力によるクラック発生を防ぐことができると共に柱状絶縁性部材の正確な位置決めが可能なチップ型サージアブソーバ及びその製造方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明は、上記課題を解決するため、以下の手段を採用する。
本発明のチップ型サージアブソーバは、周面に中央の放電ギャップを介して導電性被膜が分割形成された柱状の絶縁性部材と、該絶縁性部材の両端に対向配置され前記導電性被膜に接触する一対の端子電極部材と、前記一対の端子電極部材を両端に配して前記絶縁性部材を内部に不活性ガスと共に封止する絶縁性管とを備えたチップ型サージアブソーバであって、前記端子電極部材が、前記絶縁性管の端面と融着材料で接着されるフランジ部と、該フランジ部を基端として前記絶縁性管の内側において軸方向に突出すると共に径方向内側面で前記絶縁性部材を支持する突出支持部とを備え、前記突出支持部の径方向外側面が、基端側の少なくとも一部で前記絶縁性管の径方向内側面に接すると共に先端側で前記絶縁性管の径方向内側面から離間するよう形成されていることを特徴とする。
【０００８】
また、本発明のチップ型サージアブソーバの製造方法は、周面に中央の放電ギャップを介して導電性被膜が分割形成された柱状の絶縁性部材を、該絶縁性部材の両端に対向配置され前記導電性被膜に接触する一対の端子電極部材と絶縁性管とによって不活性ガスと共に内部に封止する封止工程を備えるチップ型サージアブソーバの製造方法であって、前記封止工程が、前記端子電極部材と前記絶縁性管の端面とを融着材料で接着する工程を有し、前記端子電極部材が、前記絶縁性管の端面と接着されるフランジ部と、該フランジ部を基端として前記絶縁性管の内側において軸方向に突出すると共に径方向内側面で前記絶縁性部材を支持する突出支持部とを備え、前記突出支持部の径方向外側面が、基端側の少なくとも一部で前記絶縁性管の径方向内側面に接すると共に先端側で前記絶縁性管の径方向内側面から離間するよう形成されていることを特徴とする。
【０００９】
このチップ型サージアブソーバは、上記構成を有するとともに上記の製造方法によって製造され、突出支持部の径方向外側面が、基端側の少なくとも一部で絶縁性管の径方向内側面に接するので、突出支持部の径方向外側面の基端側で端子電極部材が正確に位置決めされる。また、先端側で絶縁性管の径方向内側面から離間するよう形成されているので、面実装時の温度変化試験または温度変化の繰り返し試験により熱応力や衝撃が発生しても、突出支持部と絶縁性管との隙間でこれらを逃がして緩和させることができる。
なお、上記突出支持部の径方向は、より詳しくは突出支持部の軸方向を中心とした場合の径方向を指すものである。
【００１０】
また、本発明のチップ型サージアブソーバは、前記チップ型サージアブソーバであって、前記突出支持部の径方向外側面が、基端から先端に向けて前記絶縁性管の径方向内側面から漸次離間するテーパ形状とされていることが好ましい。
このチップ型サージアブソーバは、上記の構成を有するので、応力緩和効果だけでなく、突出支持部に絶縁性管を装着する際、テーパ形状の上記径方向外側面に沿って装着することによってスムーズに組立できるとともに正確に位置決めすることができる。また、フランジ部と絶縁性管とをろう材で接着する際に、溶融したろう材が突状支持部の径方向外側面と絶縁性管の内周面との隙間を毛細管現象で延びようとしても、突出支持部の先端側ほど隙間が広がるためこれを抑制することができる。
【００１１】
また、本発明のチップ型サージアブソーバは、前記チップ型サージアブソーバであって、前記突出支持部の径方向内側面が、基端を中心に向けた傾斜面とされていることが好ましい。
このチップ型サージアブソーバは、上記の構成を有するので、絶縁性部材の周面ではなく隅部と突状支持部の径方向内側面とが線状で接触する。したがって、接触していない部分に形成される隙間によって端子電極部材と絶縁性部材との間で伝達される応力等を緩和することができる。また、傾斜面に沿って絶縁性部材を装着することができ、絶縁性部材の位置決めを容易に行うことができる。
【００１２】
また、本発明のチップ型サージアブソーバは、前記チップ型サージアブソーバであって、前記突出支持部が、その径方向内側面に囲まれた凹部の底面と前記絶縁性部材との間に空隙を設けて絶縁性部材を支持することが好ましい。
このチップ型サージアブソーバは、上記の構成を有するので、軸方向の応力を空隙によってより効果的に緩和することができる。
【００１３】
また、本発明のチップ型サージアブソーバは、前記チップ型サージアブソーバであって、前記絶縁性部材の導電性被膜と前記端子電極部材とが、絶縁性部材よりも硬度の低い金属部材を介して接触していることが好ましい。
このチップ型サージアブソーバは、上記の構成を有するので、絶縁性部材と端子電極部材との間で伝達される応力を金属部材で吸収して緩和することができる。
【００１４】
また、本発明のチップ型サージアブソーバは、前記チップ型サージアブソーバであって、前記絶縁性管が、セラミックス材料で形成されていることが好ましい。
このチップ型サージアブソーバは、上記構成を有するので、ガラス材料に比べて大きなサージ耐量を付加させることができる。
【００１５】
【発明の実施の形態】
本発明の第１の実施形態について、図１から図４を参照して説明する。
本実施形態に係るチップ型サージアブソーバ１は、図１に示すように、マイクロギャップを使用した放電型サージアブソーバである。このチップ型サージアブソーバ１は、周面に中央の放電ギャップ２を介して導電性被膜３が分割形成された円柱状セラミックス部材（絶縁性部材）５と、この円柱状セラミックス部材５の両端に対向配置され導電性被膜３に接触する一対の端子電極部材６、７と、一対の端子電極部材６、７を両端に配して円柱状セラミックス部材５を内部にＡｒ（アルゴン）等の不活性ガスと共に封止する筒型セラミックス（絶縁性管）８とを備えている。
【００１６】
円柱状セラミックス部材５は、ムライト焼結体等のセラミックス材料からなり隅部が曲面とされている。また、表面に導電性被膜３としてスパッタリング法、蒸着法、イオンプレーティング法等の薄膜形成技術によるＴｉＮ（窒化チタン）等の薄膜が形成されている。
放電ギャップ２は、レーザーカット、ダイシング、エッチング等の加工によって０．０１〜１．５ｍｍの幅で１〜１００本形成されるが、本実施形態では、７０μｍ幅のものを１本形成している。
【００１７】
一対の端子電極部材６、７は、Ｆｅ（鉄）、Ｎｉ（ニッケル）、Ｃｏ（コバルト）合金であるコバール（ＫＯＶＡＲ：登録商標）等の金属で構成されている。
この一対の端子電極部材６、７は、図２及び図３に示すように、それぞれ筒型セラミックス８の端面８ａと銀を含むろう材（融着材料）１０で接着される縦横比が１以下とされた長方形状のフランジ部１１と、このフランジ部１１を基端として筒型セラミックス８の内側において軸方向に突出すると共に内周面（径方向内側面）１２ａで円柱状セラミックス部材５を支持する環状支持部（突出支持部）１２とを備えている。
一対の端子電極部材６、７は、プレス加工によって成形されている。
【００１８】
環状支持部１２の外周面（径方向外側面）１２ｂは、フランジ部１１側の基端で筒型セラミックス８の内周面に接するとともにこの基端から先端に向けて筒型セラミックス８の内周面から漸次離間するテーパ形状とされている。内周面１２ａは、円柱状セラミックス部材５の曲面状の隅部と接触して係合されるように断面円弧状に形成された曲面であるとともに、フランジ部１１側の基端を中心に向けた傾斜面とされている。
環状支持部１２の内周面１２ａに囲まれて形成される凹部の底面１２ｃと円柱状セラミックス部材５との間に空隙１５が形成されている。
【００１９】
筒型セラミックス８は、図１に示すように、断面長方形状を有し両端面外形がフランジ部１１の外周寸法と一致している。この筒型セラミックス８は、例えばアルミナ等の絶縁性セラミックスからなり、両端面には、例えば、Ｍｏ（モリブデン）−Ｗ（タングステン）のメタライズ処理、Ｎｉ（ニッケル）メッキによってメタライズ層が形成されている。
この筒型セラミックス８と一対の端子電極部材６、７とによって円柱状セラミックス部材５等がＡｒ等の不活性ガスとともに封止されている。
【００２０】
次に、以上の構成からなる本実施形態のサージアブソーバ１の製造方法について説明する。
まず、端子電極部材６の底面１２ｃ上に、円柱状セラミックス部材５を載置して内周面１２ａと接触させる。そして、フランジ部１１の上にろう材１０を載置しその上に筒型セラミックス８を載置する。さらに、筒型セラミックス８の上部にろう材１０を載置し、端子電極部材７と円柱状セラミックス部材５とを環状支持部１２の外周面１２ｂに接触させて仮組する。
上述のように仮組した状態で真空引き後Ａｒ雰囲気下とし、加熱処理によってろう材１０を溶融させて封止する。その後、外周面にＮｉ、Ｓｎ（スズ）メッキを施しチップ型サージアブソーバ１を製造する。なお、外周面のメッキは、Ｎｉ、Ｓｎに限らず、Ｎｉの代わりにＣｕ（銅）、Ｓｎの代わりにＳｎ／Ｐｂ（鉛）等の表面実装に適するメッキで構わない。
こうして製造したチップ型サージアブソーバ１を、例えば、図４に示すように、プリント基板等の基板Ｂ上に筒型セラミックス８の一側面である実装面８Ａを基板Ｂ上に載置し、基板Ｂと一対の端子電極部材６、７の外面とを半田Ｓによって接着固定して使用する。
【００２１】
このチップ型サージアブソーバ１によれば、環状支持部１２の外周面１２ｂが、基端から先端に向けて筒型セラミックス８の内周面から漸次離間するテーパ形状とされているので、環状支持部１２に筒型セラミックス８を装着する際、テーパ形状の外周面１２ｂに沿って装着することによってスムーズに組立できるとともに、外周面１２ｂの基端側で一対の端子電極部材６、７それぞれを正確に位置決めすることができる。この際、先端側で筒型セラミックス８の内周面１２ａから離間されているので、面実装時のフロー実装による熱衝撃や温度サイクル試験等による熱応力により衝撃が発生しても、環状支持部１２と筒型セラミックス８との隙間でこれらを逃がして緩和させることができる。
【００２２】
また、応力緩和効果だけでなく、フランジ部１１と筒型セラミックス８とをろう材１０で接着する際に、溶融したろう材１０が環状支持部１２の外周面１２ｂと筒型セラミックス８の内周面との隙間を毛細管現象で延びようとしても、環状支持部１２の先端側ほど隙間が広がるためこれを抑制することができる。
さらに、円柱状セラミックス部材５と内周面１２ａとの接触が円柱状セラミックス部材５の周面全体でなく隅部と線状で接触されているので、接触していない部分に形成される隙間によって一対の端子電極部材６、７と円柱状セラミックス部材５との間で伝達される応力等を緩和することができる。また、内周面１２ａに沿って円柱状セラミックス部材５を装着することができ、円柱状セラミックス部材５の位置決めを容易に行うことができる。
【００２３】
また、環状支持部１２が、内周面１２ａに囲まれた凹部の底面１２ｃと円柱状セラミックス部材５との間に空隙１５を設けて円柱状セラミックス部材５を支持しているので、円柱状セラミックス部材５と一対の端子電極部材６、７との間で伝達される軸方向の応力を空隙１５によってより効果的に緩和することができる。
さらに、筒型セラミックス８がセラミックス材料で形成されているので、ガラス材料に比べて大きなサージ耐量を付加させることができる。
【００２４】
次に、本発明に係る第２の実施形態について、図５を参照して説明する。なお、以下の説明において、上記実施形態において説明した構成要素には同一符号を付し、その説明は省略する。
第２の実施形態が上記第１の実施形態と異なる点は、円柱状セラミックス部材５の両端に円柱状セラミックス部材５よりも硬度の低いステンレス等のキャップ電極（金属部材）１６が配設され、このキャップ電極１６と一対の端子電極部材６、７とが接触しているとした点である。
【００２５】
このチップ型サージアブソーバ１７のキャップ電極１６は椀状に形成され、外周部１８がフランジ部１１の環状支持部１２の先端よりも軸方向内方に延びて断面略Ｕ字状に形成され主放電部とされている。
円柱状セラミックス部材５の導電性被膜３は、キャップ電極１６の内周面で接触し、キャップ電極１６は、環状支持部１２の内周面１２ａに接触して支持されている。
【００２６】
このチップ型サージアブソーバ１７は、第１の実施形態に係るチップ型サージアブソーバ１と同様の作用・効果を有するが、上述のキャップ電極１６を備えているので、円柱状セラミックス部材５と一対の端子電極部材６、７との間で伝達される応力をキャップ電極１６で吸収して緩和することができる。
【００２７】
なお、本発明の技術範囲は上記実施の形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲において種々の変更を加えることが可能である。
例えば、上記空隙１５は、円柱状セラミックス部材５の両端側でも何れか一方の端部側のみであっても同様の効果を奏する。
また、キャップ電極１６は複数金属層からなるものでもよく、さらにこの際、各金属層の硬度を内側から外側に向けて傾斜的に徐々に変化させてもよい。
【００２８】
さらに、円柱状セラミックス部材５の導電性被膜は、Ａｇ、Ａｇ／Ｐｄ合金、ＳｎＯ_２、Ａｌ、Ｎｉ、Ｃｕ、Ｔｉ、Ｔａ、Ｗ、ＳｉＣ、ＢａＡｌ、Ｃ、Ａｇ／Ｐｔ合金、ＩＴＯ、ＴｉＣ、ＴｉＣＮ等でもよい。
また、端子電極部材は、ＣｕやＮｉ系の合金でもよい。
また、絶縁性管両端面のメタライズ層は、Ａｇ、Ｃｕ、Ａｕ、Ｍｏ−Ｍｎのメタライズ処理後のＮｉメッキでも良く、また、メタライズ層を用いず活性金属ろう材だけで封止しても構わない。
また、封止する際の雰囲気、すなわち内部の不活性ガスは、放電特性に応じて決定され、例えば、大気（空気）でもよく、Ｎ_２、Ｎｅ、Ｈｅ、Ｘｅ、Ｈ_２、ＳＦ_６、Ｃ_２Ｆ_６、Ｃ_３Ｆ_８、ＣＯ_２、及びこれらの混合ガスでもよい。
【００２９】
【発明の効果】
以上説明した本発明においては以下の効果を奏する。
本発明のチップ型サージアブソーバによれば、基板に面実装した場合でも熱応力による柱状絶縁性部材のクラック発生を防ぐことができると共に、絶縁性管や端子電極部材に対して柱状絶縁性部材の正確な位置決めが可能となる。したがって、安定した放電特性を長期にわたって有するチップ型サージアブソーバを得ることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に係るチップ型サージアブソーバを示す軸方向断面図である。
【図２】本発明の第１の実施形態に係るチップ型サージアブソーバの端子電極部材を示す正面図である。
【図３】図２のＸ−Ｘにおける断面図である。
【図４】本発明の第１の実施形態に係るチップ型サージアブソーバを基板上に実装したときを示す断面図である。
【図５】本発明の第２の実施形態に係るチップ型サージアブソーバを示す軸方向断面図である。
【符号の説明】
１、１７チップ型サージアブソーバ
２放電ギャップ
３導電性被膜
５円柱状セラミックス部材（絶縁性部材）
６、７端子電極部材
８筒型セラミックス（絶縁性管）
１１フランジ部
１２環状支持部（突出支持部）
１２ａ内周面（径方向内側面）
１２ｂ外周面（径方向外側面）
１２ｃ底面
１５空隙
１６キャップ電極（金属部材）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chip-type surge absorber used for protecting various devices from surges and preventing accidents, and a method for manufacturing the same.
[0002]
[Prior art]
Portions where electronic devices for communication equipment such as telephones, facsimiles, modems, etc. are connected to communication lines, power lines, antennas, CRT drive circuits, etc. A surge absorber is connected to prevent damage due to thermal damage or ignition of an electronic device or a printed circuit board on which the device is mounted due to an abnormal voltage.
[0003]
Conventionally, for example, a surge absorber using a surge absorbing element having a micro gap has been proposed. In this surge absorber, a so-called microgap is formed on the peripheral surface of a cylindrical ceramic member coated with a conductive coating, and a surge absorbing element having a pair of cap electrodes at both ends of the ceramic member is housed in a glass tube together with an inert gas. A discharge type surge absorber in which sealing electrodes having lead wires at both ends of a cylindrical glass tube are sealed by high-temperature heating (see, for example, Patent Documents 1 and 2).
[0004]
On the other hand, in order to absorb the thermal expansion of the cylindrical ceramic member and prevent the occurrence of cracks in the glass tube, a technique for sandwiching the buffer member between the terminal electrode and the cylindrical ceramic member has been proposed (for example, Patent Document 3). reference).
In recent years, surface-mounting is also progressing in such a discharge type surge absorber. As an example applied to the surge absorber, as a surface mount type (Melph type), there is no lead wire in the sealing electrode, and when mounting, the sealing electrode and the substrate side are fixed by soldering is there.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-110311 (FIG. 1)
[Patent Document 2]
Japanese Examined Patent Publication No. 7-24234 (FIG. 3A)
[Patent Document 3]
Japanese Patent Laid-Open No. 2000-138089 (FIG. 1)
[0006]
[Problems to be solved by the invention]
However, the following problems remain in the conventional surge absorber as found in Patent Document 2. That is, when a conventional surge absorber is surface-mounted, the surge absorber is in close contact with the mounting board, unlike when it is attached with lead wires, so the thermal expansion difference between the mounting board and the surge absorber due to a temperature change test or repeated temperature change test For this reason, there is a risk that cracks due to stress may occur in the cylindrical ceramic member inside the surge absorber. For this reason, the discharge start voltage rose, and the performance as an absorber could not be fully exhibited. In the case of the surge absorber using the conventional buffer member, the cylindrical ceramic member may be displaced from the central axis even if stress relaxation is possible.
The present invention has been made in view of the above-described problems. A chip-type surge absorber capable of preventing the occurrence of cracks due to thermal stress even when surface-mounted and capable of accurately positioning a columnar insulating member, and a method for manufacturing the same The purpose is to provide.
[0007]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
The chip-type surge absorber according to the present invention includes a columnar insulating member having a conductive film divided and formed on the peripheral surface through a central discharge gap, and is disposed opposite to both ends of the insulating member so as to contact the conductive film. A chip-type surge absorber comprising: a pair of terminal electrode members; and an insulating tube that seals the insulating member together with an inert gas by arranging the pair of terminal electrode members at both ends, A terminal electrode member has a flange portion bonded to the end surface of the insulating tube with a fusion material, and protrudes in the axial direction inside the insulating tube with the flange portion serving as a base end, and is insulated on the radially inner side surface. And a radially outer surface of the projecting support portion is in contact with a radially inner side surface of the insulating tube at least at a part on the proximal end side, and the insulating tube on the distal end side. Away from the radial inner surface of It characterized in that it is formed so as to.
[0008]
Further, the manufacturing method of the chip-type surge absorber according to the present invention includes a columnar insulating member having a conductive film divided and formed on the peripheral surface through a central discharge gap, and disposed opposite to both ends of the insulating member. A method for manufacturing a chip-type surge absorber comprising a sealing step of sealing together with an inert gas by a pair of terminal electrode members and an insulating tube in contact with a conductive coating, wherein the sealing step includes the terminal A step of adhering an electrode member and an end surface of the insulating tube with a fusion material, the terminal electrode member being bonded to the end surface of the insulating tube, and the flange portion as a base end A protruding support portion that protrudes in the axial direction inside the insulating tube and supports the insulating member on a radially inner side surface, and the radially outer surface of the protruding support portion is at least partly on the proximal side. Diameter of the insulating tube Characterized in that it is formed to be separated at the distal end side with contact countercurrently inner surface from the radially inner surface of the insulating tube.
[0009]
Since this chip type surge absorber has the above-described configuration and is manufactured by the above-described manufacturing method, the radially outer surface of the projecting support portion is in contact with the radially inner surface of the insulating tube at least at a part of the proximal end side. The terminal electrode member is accurately positioned on the base end side of the radially outer surface of the protruding support portion. In addition, since it is formed so as to be separated from the radially inner side surface of the insulating tube on the tip side, even if thermal stress or impact occurs due to a temperature change test during surface mounting or a repeated test of temperature change, the protruding support part These can be released and relaxed in the gap between the insulating tube and the insulating tube.
In addition, the radial direction of the said protrusion support part points out the radial direction when centering on the axial direction of a protrusion support part in more detail.
[0010]
The tip type surge absorber according to the present invention is the tip type surge absorber, wherein the radially outer surface of the protruding support portion is gradually separated from the radially inner side surface of the insulating tube from the proximal end to the distal end. It is preferable that it is set as the taper shape which carries out.
Since this chip type surge absorber has the above-described configuration, not only the stress relaxation effect, but also when mounting an insulating tube on the protruding support part, it is smoothly mounted by mounting along the radially outer surface of the tapered shape. It can be assembled and positioned accurately. Further, when the flange portion and the insulating tube are bonded with the brazing material, the molten brazing material tries to extend the gap between the radially outer surface of the projecting support portion and the inner peripheral surface of the insulating tube by a capillary phenomenon. However, since the gap widens toward the tip end side of the protruding support portion, this can be suppressed.
[0011]
The chip-type surge absorber according to the present invention is preferably the chip-type surge absorber, wherein the radially inner side surface of the protruding support part is an inclined surface with the base end as the center.
Since this chip-type surge absorber has the above-described configuration, the corner portion and the radially inner side surface of the projecting support portion are in linear contact with each other instead of the peripheral surface of the insulating member. Therefore, the stress transmitted between the terminal electrode member and the insulating member can be relieved by the gap formed in the non-contact portion. Further, the insulating member can be mounted along the inclined surface, and the insulating member can be easily positioned.
[0012]
The chip-type surge absorber according to the present invention is the chip-type surge absorber, wherein the projecting support portion is provided with a gap between the bottom surface of the recess surrounded by the radially inner side surface and the insulating member. It is preferable to support the insulating member.
Since this chip-type surge absorber has the above-described configuration, the stress in the axial direction can be more effectively reduced by the air gap.
[0013]
The chip type surge absorber according to the present invention is the chip type surge absorber, wherein the conductive coating of the insulating member and the terminal electrode member are in contact with each other through a metal member having a hardness lower than that of the insulating member. It is preferable.
Since this chip type surge absorber has the above-described configuration, the stress transmitted between the insulating member and the terminal electrode member can be absorbed by the metal member and relaxed.
[0014]
The chip type surge absorber according to the present invention is preferably the chip type surge absorber, wherein the insulating tube is formed of a ceramic material.
Since this chip-type surge absorber has the above-described configuration, it is possible to add a large surge resistance compared to a glass material.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
The chip type surge absorber 1 according to the present embodiment is a discharge type surge absorber using a micro gap as shown in FIG. This chip-type surge absorber 1 has a cylindrical ceramic member (insulating member) 5 in which a conductive coating 3 is divided and formed on the peripheral surface via a central discharge gap 2, and faces both ends of the cylindrical ceramic member 5. A pair of terminal electrode members 6 and 7 disposed and in contact with the conductive coating 3 and a pair of terminal electrode members 6 and 7 are arranged at both ends, and the columnar ceramic member 5 is contained in an inert gas such as Ar (argon). And a cylindrical ceramic (insulating tube) 8 that is sealed together.
[0016]
The cylindrical ceramic member 5 is made of a ceramic material such as a mullite sintered body and has corners that are curved. Further, a thin film such as TiN (titanium nitride) is formed on the surface as a conductive coating 3 by a thin film forming technique such as sputtering, vapor deposition, or ion plating.
1 to 100 discharge gaps 2 having a width of 0.01 to 1.5 mm are formed by processing such as laser cutting, dicing, and etching. In the present embodiment, one discharge gap 2 having a width of 70 μm is formed. .
[0017]
The pair of terminal electrode members 6 and 7 are made of a metal such as Kovar (KOVAR), which is an Fe (iron), Ni (nickel), or Co (cobalt) alloy.
As shown in FIGS. 2 and 3, the pair of terminal electrode members 6 and 7 have an aspect ratio of 1 or less bonded to the end surface 8a of the cylindrical ceramic 8 and a brazing material (fusion material) 10 containing silver. A rectangular flange portion 11 having a flange portion 11 and a cylindrical ceramic member 5 supported by an inner peripheral surface (radially inner surface) 12a while projecting in the axial direction inside the cylindrical ceramic 8 with the flange portion 11 as a base end. An annular support portion (protruding support portion) 12 is provided.
The pair of terminal electrode members 6 and 7 are formed by press working.
[0018]
The outer peripheral surface (radial outer surface) 12b of the annular support portion 12 is in contact with the inner peripheral surface of the cylindrical ceramic 8 at the base end on the flange portion 11 side, and the inner periphery of the cylindrical ceramic 8 from the base end toward the front end. The taper shape is gradually separated from the surface. The inner peripheral surface 12a is a curved surface formed in a circular arc shape so as to come into contact with and engage with a curved corner of the cylindrical ceramic member 5, and the proximal end on the flange portion 11 side is directed toward the center. It is considered as an inclined surface.
A gap 15 is formed between the bottom surface 12 c of the recess formed by being surrounded by the inner peripheral surface 12 a of the annular support portion 12 and the cylindrical ceramic member 5.
[0019]
As shown in FIG. 1, the cylindrical ceramic 8 has a rectangular cross section and the outer shape of both end faces coincides with the outer peripheral dimension of the flange portion 11. The cylindrical ceramic 8 is made of, for example, an insulating ceramic such as alumina, and metallized layers are formed on both end surfaces by, for example, Mo (molybdenum) -W (tungsten) metallization or Ni (nickel) plating. .
The cylindrical ceramic member 5 and the like are sealed together with an inert gas such as Ar by the cylindrical ceramic 8 and the pair of terminal electrode members 6 and 7.
[0020]
Next, a method for manufacturing the surge absorber 1 of the present embodiment having the above configuration will be described.
First, the cylindrical ceramic member 5 is placed on the bottom surface 12c of the terminal electrode member 6 and brought into contact with the inner peripheral surface 12a. And the brazing material 10 is mounted on the flange part 11, and the cylindrical ceramic 8 is mounted on it. Further, the brazing material 10 is placed on the upper part of the cylindrical ceramic 8, and the terminal electrode member 7 and the cylindrical ceramic member 5 are brought into contact with the outer peripheral surface 12 b of the annular support portion 12 and temporarily assembled.
In the temporarily assembled state as described above, after vacuuming, an Ar atmosphere is set, and the brazing filler metal 10 is melted and sealed by heat treatment. Then, Ni and Sn (tin) plating are given to an outer peripheral surface, and the chip type surge absorber 1 is manufactured. The plating on the outer peripheral surface is not limited to Ni and Sn, but may be plating suitable for surface mounting such as Cu (copper) instead of Ni and Sn / Pb (lead) instead of Sn.
For example, as shown in FIG. 4, the chip-type surge absorber 1 manufactured in this way is mounted on the substrate B with a mounting surface 8 </ b> A, which is one side surface of the cylindrical ceramics 8, on the substrate B such as a printed circuit board. And the outer surfaces of the pair of terminal electrode members 6 and 7 are used by being bonded and fixed with solder S.
[0021]
According to this chip type surge absorber 1, the outer peripheral surface 12b of the annular support portion 12 is tapered so as to gradually move away from the inner peripheral surface of the cylindrical ceramic 8 from the proximal end toward the distal end. When the cylindrical ceramic 8 is mounted on the outer peripheral surface 12b, it can be smoothly assembled by mounting along the tapered outer peripheral surface 12b, and each of the pair of terminal electrode members 6 and 7 can be accurately connected to the base end side of the outer peripheral surface 12b. Can be positioned. At this time, the annular support portion is separated from the inner peripheral surface 12a of the cylindrical ceramic 8 on the front end side, even if an impact occurs due to thermal shock due to flow mounting during surface mounting or thermal stress due to a temperature cycle test or the like. These can be released and relaxed in the gap between 12 and the cylindrical ceramic 8.
[0022]
In addition to the stress relaxation effect, when the flange portion 11 and the cylindrical ceramic 8 are bonded to each other with the brazing material 10, the molten brazing material 10 is mixed with the outer peripheral surface 12 b of the annular support portion 12 and the inner periphery of the cylindrical ceramic 8. Even if the gap with the surface is extended by capillary action, the gap is widened toward the distal end side of the annular support portion 12, and this can be suppressed.
Furthermore, since the contact between the cylindrical ceramic member 5 and the inner peripheral surface 12a is not in the whole peripheral surface of the cylindrical ceramic member 5, but in contact with the corners, the gap is formed in the non-contact portion. The stress transmitted between the pair of terminal electrode members 6 and 7 and the cylindrical ceramic member 5 can be relaxed. Further, the cylindrical ceramic member 5 can be mounted along the inner peripheral surface 12a, and the cylindrical ceramic member 5 can be easily positioned.
[0023]
Further, since the annular support portion 12 supports the cylindrical ceramic member 5 by providing the gap 15 between the bottom surface 12c of the recess surrounded by the inner peripheral surface 12a and the cylindrical ceramic member 5, the cylindrical ceramic member 5 is supported. The stress in the axial direction transmitted between the member 5 and the pair of terminal electrode members 6 and 7 can be relaxed more effectively by the gap 15.
Furthermore, since the cylindrical ceramics 8 are formed of a ceramic material, it is possible to add a surge resistance greater than that of a glass material.
[0024]
Next, a second embodiment according to the present invention will be described with reference to FIG. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
The second embodiment differs from the first embodiment in that cap electrodes (metal members) 16 such as stainless steel having a hardness lower than that of the cylindrical ceramic member 5 are disposed at both ends of the cylindrical ceramic member 5. The cap electrode 16 and the pair of terminal electrode members 6 and 7 are in contact with each other.
[0025]
The cap electrode 16 of the chip-type surge absorber 17 is formed in a bowl shape, and the outer peripheral portion 18 extends inward in the axial direction from the tip of the annular support portion 12 of the flange portion 11 and has a substantially U-shaped cross section. It is considered to be a part.
The conductive coating 3 of the cylindrical ceramic member 5 is in contact with the inner peripheral surface of the cap electrode 16, and the cap electrode 16 is in contact with and supported by the inner peripheral surface 12 a of the annular support portion 12.
[0026]
The chip-type surge absorber 17 has the same functions and effects as the chip-type surge absorber 1 according to the first embodiment, but includes the cap electrode 16 described above, so that the cylindrical ceramic member 5 and a pair of terminals are provided. The stress transmitted between the electrode members 6 and 7 can be absorbed by the cap electrode 16 and relaxed.
[0027]
The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the void 15 has the same effect whether it is on either side of the cylindrical ceramic member 5 or only one of the ends.
The cap electrode 16 may be composed of a plurality of metal layers, and at this time, the hardness of each metal layer may be gradually changed from the inside toward the outside.
[0028]
Further, the conductive coating of the cylindrical ceramic member 5 is made of Ag, Ag / Pd alloy, SnO ₂ , Al, Ni, Cu, Ti, Ta, W, SiC, BaAl, C, Ag / Pt alloy, ITO, TiC, TiCN or the like may be used.
The terminal electrode member may be a Cu or Ni-based alloy.
Further, the metallization layers on both end faces of the insulating tube may be Ni plating after the metallization treatment of Ag, Cu, Au, Mo—Mn, or may be sealed only with the active metal brazing material without using the metallization layer. Absent.
Further, the atmosphere at the time of sealing, that is, the inert gas inside is determined according to the discharge characteristics, and may be air (air), for example, N ₂ , Ne, He, Xe, H ₂ , SF ₆ , C ₂ F ₆ , C ₃ F ₈ , CO ₂ , and a mixed gas thereof may be used.
[0029]
【The invention's effect】
The present invention described above has the following effects.
According to the chip-type surge absorber of the present invention, it is possible to prevent the columnar insulating member from cracking due to thermal stress even when it is surface-mounted on the substrate, and to prevent the columnar insulating member from Accurate positioning is possible. Therefore, a chip-type surge absorber having stable discharge characteristics over a long period can be obtained.
[Brief description of the drawings]
FIG. 1 is an axial sectional view showing a chip-type surge absorber according to a first embodiment of the present invention.
FIG. 2 is a front view showing a terminal electrode member of the chip-type surge absorber according to the first embodiment of the present invention.
3 is a cross-sectional view taken along the line XX in FIG.
FIG. 4 is a cross-sectional view showing the chip type surge absorber according to the first embodiment of the present invention mounted on a substrate.
FIG. 5 is an axial sectional view showing a chip type surge absorber according to a second embodiment of the present invention.
[Explanation of symbols]
1, 17 Chip type surge absorber 2 Discharge gap 3 Conductive coating 5 Cylindrical ceramic member (insulating member)
6, 7 Terminal electrode member 8 Cylindrical ceramics (insulating tube)
11 Flange part 12 Annular support part (projection support part)
12a Inner peripheral surface (radial inner surface)
12b Outer peripheral surface (radially outer surface)
12c bottom 15 gap 16 cap electrode (metal member)

Claims

A columnar insulating member in which a conductive coating is divided and formed on the peripheral surface via a central discharge gap; a pair of terminal electrode members disposed opposite to both ends of the insulating member and in contact with the conductive coating; A chip type surge absorber provided with a pair of terminal electrode members at both ends and an insulating tube for sealing the insulating member together with an inert gas inside,
The flange portion where the terminal electrode member is bonded to the end face of the insulating tube with a fusion material;
A protruding support portion that protrudes in the axial direction inside the insulating tube with the flange portion as a base end and supports the insulating member on a radially inner side surface;
A radially outer surface of the protruding support portion is formed so as to be in contact with the radially inner side surface of the insulating tube at at least a part of the proximal end side and to be separated from the radially inner side surface of the insulating tube on the distal end side. A chip-type surge absorber.

2. The chip type according to claim 1, wherein a radially outer surface of the protruding support portion has a tapered shape that gradually separates from a radially inner surface of the insulating tube from a proximal end to a distal end. surge absorber.

3. The chip-type surge absorber according to claim 1, wherein a radially inner side surface of the protruding support portion is an inclined surface with a base end as a center.

4. The protruding support portion supports the insulating member by providing a gap between the bottom surface of the recess surrounded by the radially inner side surface and the insulating member. The chip type surge absorber according to one.

5. The conductive film of the insulating member and the terminal electrode member are in contact with each other through a metal member having a hardness lower than that of the insulating member. Chip type surge absorber.

6. The chip-type surge absorber according to claim 1, wherein the insulating tube is made of a ceramic material.

A columnar insulating member having a conductive film divided and formed on the peripheral surface through a central discharge gap is insulative with a pair of terminal electrode members disposed opposite to both ends of the insulating member and in contact with the conductive film. A chip-type surge absorber manufacturing method comprising a sealing step for sealing inside with an inert gas by a tube,
The sealing step includes a step of bonding the terminal electrode member and an end surface of the insulating tube with a fusion material,
A flange portion where the terminal electrode member is bonded to an end face of the insulating tube;
A protruding support portion that protrudes in the axial direction inside the insulating tube with the flange portion as a base end and supports the insulating member on a radially inner side surface;
A radially outer surface of the protruding support portion is formed so as to be in contact with the radially inner side surface of the insulating tube at at least a part of the proximal end side and to be separated from the radially inner side surface of the insulating tube on the distal end side. A method for manufacturing a chip-type surge absorber.