JP4263543B2

JP4263543B2 - Protective element

Info

Publication number: JP4263543B2
Application number: JP2003177588A
Authority: JP
Inventors: 康彦冨高; 孝五十嵐
Original assignee: Uchihashi Estec Co Ltd
Current assignee: Uchihashi Estec Co Ltd
Priority date: 2003-02-05
Filing date: 2003-06-23
Publication date: 2009-05-13
Anticipated expiration: 2023-06-23
Also published as: JP2004296422A

Description

【０００１】
【発明の属する技術分野】
本発明は抵抗体付き温度ヒューズ等の保護素子に関するものである。
【０００２】
【従来の技術】
抵抗体付き温度ヒューズは、可溶合金からなるヒューズエレメントを有し、通電発熱によって前記ヒューズエレメントを溶断させる抵抗体を備え、異常検出回路との組合せで使用され、その使用において機器の異常、例えば異常電圧を異常検出回路で検出し、この検出で抵抗体を通電発熱させ、この発生熱でヒューズエレメントを溶断させて機器への通電を遮断している。
また、ヒューズエレメントの融点を機器許容温度に設定し、機器が許容温度に達したときにヒューズエレメントを溶断させて機器の異常発熱ひいては火災の未然防止に使用することもできる。
【０００３】
図９の（イ）は従来の抵抗体付き温度ヒューズの一例を示す図面、図９の（ロ）は図９の（イ）におけるロ−ロ断面図である。
図９において、１’はセラミックス基板等の絶縁基板、２０’〜２３’は絶縁基板上に導電ペーストの印刷・焼き付けにより設けた電極である。４’は第１電極２１’と第２電極２２’間に溶接等により連結したヒューズエレメントであり、中間電極２０’にも接合してある。３’は第３電極２３’と中間電極２０’との間に連結した膜抵抗であり、抵抗ペーストの印刷・焼付けにより設けてある。５’は膜抵抗３’に対するオーバーコートであり、ガラスペーストの印刷・焼付けにより設けてあり、通常膜抵抗３’の外郭よりも３００μｍ〜１０００μｍ程度大きい外郭としてある。６’はヒューズエレメントに塗布したフラックスである。８’は絶縁カバーである。
【０００４】
上記抵抗体付き温度ヒューズの動作機構は次のとおりである。
すなわち、常時では、膜抵抗が非通電とされ、ヒューズエレメントが機器と電源間に挿入されて通電される。異常時に膜抵抗が通電発熱され、この発生熱でヒューズエレメントが溶融され、溶融合金が既溶融フラックスとの共存下電極への濡れ拡がりにより球状化分断され、この分断により膜抵抗の通電が遮断され、分断合金の冷却凝固により非復帰のカットオフが終結される。
また、ヒューズエレメントの融点を機器の許容温度に設定しておけば、機器がほぼ許容温度に達したときにヒューズエレメントが溶融され、溶融合金が既溶融フラックスとの共存下電極への濡れ拡がりにより球状化分断され、この分断により機器への通電が遮断されて機器温度が降下され、分断合金の冷却凝固により非復帰のカットオフが終結される。
【０００５】
図１０は前記抵抗体付き温度ヒューズに対し、膜抵抗を省いた温度ヒューズを示し、後者の使用形態で使用される。
【０００６】
【発明が解決しようとする課題】
上記抵抗体付き温度ヒューズ及び温度ヒューズの何れにおいても、溶融したヒューズエレメントの電極への濡れ拡がりで動作し、従来では、中間電極２０’に両側から溶融合金が濡れ拡がってくるため中間電極２０の巾Ｗ’を第１電極２１の巾Ｗ1'や第２電極２２の巾Ｗ2'よりも広くしている。
従来、温度ヒューズや抵抗体付き温度ヒューズのヒューズエレメントには、鉛を主成分とする可溶合金が使用されていた。しかしながら、鉛は生体系に有害であり、ヒューズエレメントについても他の電器部品と同様に、鉛をはじめとする有害元素を含まない合金組成を使用することが近来強く要請されている。
かかる合金組成として、例えばＳｎ−Ｉｎ−Ｂｉ系合金が有望であるが、比抵抗値が高い値である。例えば、動作温度１３５℃の従来のヒューズエレメント合金Ｓｎ４６．５％−Ｐｂ２９．８％−Ｃｄ１６．７％−Ｉｎ７％、比抵抗値１５μΩcmに対し、ほぼ同じ動作温度のヒューズエレメント合金Ｂｉ５２％−Ｓｎ４６％−Ｉｎ２％では比抵抗値が３４μΩcmであって２倍以上である。
【０００７】
温度ヒューズや抵抗体付き温度ヒューズのヒューズエレメントの抵抗値は、負荷や自己発熱からの内部抵抗値の制約上、一定値以下に抑える必要があり、通常、比抵抗値の増大に対してはヒューズエレメント径を増大することにより対処している。
しかしながら、ヒューズエレメント径の増大は前記溶融合金量の増加を招き球状化分断性能の低下を来すことになり、これを防止するには電極面積の増大が余儀なくされ、温度ヒューズや抵抗体付き温度ヒューズの寸法増大が避けられない。
【０００８】
本発明の目的は、前記中間電極を有する抵抗体付き温度ヒューズにおいて、ヒューズエレメントの比抵抗値が高くても、良好な分断作動性能を保証することにある。
本発明の更なる目的は、上記目的に加え中間電極を有する温度ヒューズや抵抗体付き温度ヒューズの小型化を図ることにある。
【０００９】
【課題を解決するための手段】
請求項１に係る保護素子は、第１電極、第２電極、第３電極を備え、第１電極と第２電極との間に中間電極を備え、可溶合金からなるヒューズエレメントの各端が第１電極及び第２電極に接続され、同ヒューズエレメントの中間部が中間電極に接続され、中間電極と第３電極との間に膜抵抗が接続され、動作時、溶融されたヒューズエレメントの溶融合金の第１電極、第２電極のそれぞれと中間電極への濡れ拡がりによりヒューズエレメントが分断され、分断後での第１電極、第２電極のそれぞれと中間電極との間の絶縁保証のためにそれらの間を所定の絶縁距離で離隔し、中間電極のヒューズエレメント接続部位の巾が第１電極、第２電極それぞれのヒューズエレメント接続部位の巾よりも狭くされている保護素子において、ヒューズエレメントと膜抵抗が絶縁基板片面上に設けられ、膜抵抗に対するオーバコートが設けられ、中間電極の膜抵抗側片端部が膜抵抗一端部を覆い、オーバーコートの中間電極側一端部が中間電極片端部上を覆い、中間電極のヒューズエレメント接続部位から前記オーバーコート一端までの距離Ｌ 1 が、同部位から膜抵抗一端までの距離Ｌ 2 に対し、Ｌ 1 ＞Ｌ 2 −３００μｍとされていることを特徴とする。
【００１０】
請求項２に係る保護素子は、第１電極、第２電極、第３電極を備え、第１電極と第２電極との間に中間電極を備え、可溶合金からなるヒューズエレメントの各端が第１電極及び第２電極に接続され、同ヒューズエレメントの中間部が中間電極に接続され、中間電極と第３電極との間に膜抵抗が接続され、動作時、溶融されたヒューズエレメントの溶融合金の第１電極、第２電極のそれぞれと中間電極への濡れ拡がりによりヒューズエレメントが分断され、分断後での第１電極、第２電極のそれぞれと中間電極との間の絶縁保証のためにそれらの間を所定の絶縁距離で離隔し、中間電極のヒューズエレメント接続部位の巾が第１電極、第２電極それぞれのヒューズエレメント接続部位の巾よりも狭くされている保護素子において、ヒューズエレメントと膜抵抗が絶縁基板片面上に設けられ、膜抵抗に対するオーバコートが設けられ、膜抵抗一端部がオーバーコート一端より突出し、中間電極片端部が前記突出した膜抵抗一端部及びオーバーコート一端部を覆っていることを特徴とする。
【００１１】
請求項３に係る保護素子は、請求項１〜２何れかの保護素子において、ヒューズエレメントの比抵抗値が２０μΩcm以上であることを特徴とする。
【００１２】
請求項４に係る保護素子は、請求項１〜３何れかの保護素子において、可溶合金がＩｎ−Ｓｎ−Ｂｉ系合金、Ｂｉ−Ｓｎ−Ｓｂ系合金、Ｉｎ−Ｓｎ系合金、Ｉｎ−Ｂｉ系合金、Ｂｉ−Ｓｎ系合金、Ｉｎ系合金の何れかであることを特徴とする
。
【００１３】
請求項５に係る保護素子は、請求項４の保護素子において、Ｉｎ−Ｓｎ−Ｂｉ系合金の組成が（１）４３％＜Ｓｎ≦７０％，０．５％≦Ｉｎ≦１０％，残Ｂｉ、（２）２５％≦Ｓｎ≦４０％，５０％≦Ｉｎ≦５５％，残Ｂｉ、（３）２５％＜Ｓｎ≦４４％，５５％＜Ｉｎ≦７４％，１％≦Ｂｉ＜２０％、（４）４６％＜Ｓｎ≦７０％，１８％≦Ｉｎ＜４８％，１％≦Ｂｉ≦１２％、（５）５％≦Ｓｎ≦２８％，１５％≦Ｉｎ＜３７％，残Ｂｉ（但し、Ｂｉ５７．５％，Ｉｎ２５．２％，Ｓｎ１７．３％とＢｉ５４％，Ｉｎ２９．７％，Ｓｎ１６．３％のそれぞれを基準にＢｉ±２％，Ｉｎ及びＳｎ±１％の範囲を除く）、（６）１０％≦Ｓｎ≦１８％，３７％≦Ｉｎ≦４３％，残Ｂｉ、（７）２５％＜Ｓｎ≦６０％，２０％≦Ｉｎ＜５０％，１２％＜Ｂｉ≦３３％、（８）（１）〜（７）の何れか１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（９）３３％≦Ｓｎ≦４３％，０．５％≦Ｉｎ≦１０％，残Ｂｉ、（１０）４７％≦Ｓｎ≦４９％，５１％≦Ｉｎ≦５３％の１００重量部にＢｉを３〜５重量部を添加、（１１）４０％≦Ｓｎ≦４６％，７％≦Ｂｉ≦１２％，残Ｉｎ、（１２）０．３％≦Ｓｎ≦１．５％，５１％≦Ｉｎ≦５４％，残Ｂｉ、（１３）２．５％≦Ｓｎ≦１０％，２５％≦Ｂｉ≦３５％，残Ｉｎ、（１４）（９）〜（１３）の何れか１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（１５）１０％≦Ｓｎ≦２５％，４８％≦Ｉｎ≦６０％，残Ｂｉを１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、Ｂｉ−Ｓｎ−Ｓｂ系合金の組成が（１６）３０％≦Ｓｎ≦７０％，０．３％≦Ｓｂ≦２０％，残Ｂｉ、（１７）（１６）の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、Ｉｎ−Ｓｎ系合金の組成が（１８）５２％≦Ｉｎ≦８５％，残Ｓｎ、（１９）（１８）の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、Ｉｎ−Ｂｉ系合金の組成が（２０）４５％≦Ｂｉ≦５５％，残Ｉｎ、（２１）（２０）の組成の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、Ｂｉ−Ｓｎ系合金の組成が（２２）５０％＜Ｂｉ≦５６％，残Ｓｎ、（２３）（２２）の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、Ｉｎ系合金の組成が（２４）Ｉｎの１００重量部にＡｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（２５）９０％≦Ｉｎ≦９９．９％，０．１％≦Ａｇ≦１０％の１００重量部にＡｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（２６）９５％≦Ｉｎ≦９９．９％，０．１％≦Ｓｂ≦５％の１００重量部にＡｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加の何れかであることを特徴とする。
【００１４】
請求項６に係る保護素子は、請求項１〜５何れかの保護素子において、中間電極のヒューズエレメント接続部位の巾が３００〜４００μm、所定の絶縁距離が３００〜１０００μmであることを特徴とする。
【００１５】
請求項７に係る保護素子は、請求項１〜６何れかの保護素子において、中間電極の巾がヒューズエレメント接続部位とは別の部分において膨出され、第１電極及び第２電極の巾がその膨出に応じ局部的に後退または凹まされていることを特徴とする。
【００１６】
請求項８に係る保護素子は、請求項１〜７何れかの保護素子において、ヒューズエレメントと膜抵抗が絶縁基板片面上に設けられ、膜抵抗に対するオーバコートが設けられ、膜抵抗に接続された少なくとも一の電極と他の電極とが対向する部分の少なくとも一部の電極縁端部に沿いオーバーコートが延在されていることを特徴とする。
【００１７】
請求項９に係る保護素子は、請求項１〜８何れかの保護素子において、第３電極に接続されたリード導体の断面積が第１電極、第２電極のそれぞれに接続されたリード導体の断面積の０．８〜０．５倍とされていることを特徴とする。
【００１８】
【発明の実施の形態】
以下、図面を参照しつつ本発明の実施の形態について説明する。
図１は本発明に係る保護素子の一実施例を示す図面である。
図１において、１は耐熱性の絶縁基板例えばセラミックス基板である。２１、２２及び２３は導電ペーストの印刷・焼付けにより設けた第１電極、第２電極及び第３電極であり、リード導体取付け部２１０、２２０及び２３０を備えている。２０は中間電極であり、第１電極と第２電極との中間に配設し、この中間電極２０の第３電極２３側の一端部２０１の巾を第３電極２３（リード導体取付け部２３０を含まず）の巾とほぼ等しくしてある。
前記中間電極２０のヒューズエレメント接続部位の巾Ｗは第１電極、第２電極それぞれのヒューズエレメント接続部位の巾Ｗ1、Ｗ2より狭くし、Ｗ＜Ｗ1，Ｗ2としてある。通常、Ｗ1＝Ｗ2とされている。
前記第１電極２１と中間電極２０との間隔ｄ１及び第２電極２２と中間電極２０との間隔ｄ２、第３電極２３のリード導体取付け部２３０と第２電極２２との間隔ｄは、ヒューズエレメントの分断によりそれらの間が電気的に遮断されてその遮断間に回路電圧が作用しても、それらの各間隔での絶縁を保証できるように各間隔を所定距離に設定してあり、通常ｄ１＝ｄ２＜ｄとしてある。
３は膜抵抗であり、抵抗膜３の一端部３１を中間電極２０の片端部２０１に接続し、抵抗膜３の他端部３２を第３電極２３の一端部２３２に接続してある。
図１において、４は可溶合金からなるヒューズエレメントであり、第１電極２１と第２電極２２間に溶接等により接続すると共に中間を中間電極２０に溶接等により接続してある。５は膜抵抗３に対するオーバーコートである。６はヒューズエレメント４に塗布したフラックスである。７１〜７３は第１電極２１〜第３電極２３のそれぞれのリード導体取付け部２１０〜２３０に溶接等により接続したリード導体であり、溶接にはスポット抵抗溶接を用いることが好ましい。
８は絶縁被覆体であり、例えば、封止剤例えばエポキシ樹脂を塗着する構成、または封止剤層上に保護プレートを固着した構成、あるいはカバーを基板上に載置し、カバー周囲の枠のリード導体引出孔からリード導体を引出し、接着剤例えばエポキシ樹脂で封止した構成とすることができる。
【００１９】
上記において、ヒューズエレメント４には、鉛等の生体系に有害な元素を含まないＩｎ−Ｓｎ−Ｂｉ系合金、Ｂｉ−Ｓｎ−Ｓｂ系合金、Ｉｎ−Ｓｎ系合金、Ｉｎ−Ｂｉ系合金、Ｂｉ−Ｓｎ系合金、Ｉｎ系合金等を使用できる。
Ｉｎ−Ｓｎ−Ｂｉ系合金の組成には、例えば（１）４３％＜Ｓｎ≦７０％，０．５％≦Ｉｎ≦１０％，残Ｂｉ、（２）２５％≦Ｓｎ≦４０％，５０％≦Ｉｎ≦５５％，残Ｂｉ、（３）２５％＜Ｓｎ≦４４％，５５％＜Ｉｎ≦７４％，１％≦Ｂｉ＜２０％、（４）４６％＜Ｓｎ≦７０％，１８％≦Ｉｎ＜４８％，１％≦Ｂｉ≦１２％、（５）５％≦Ｓｎ≦２８％，１５％≦Ｉｎ＜３７％，残Ｂｉ（但し、Ｂｉ５７．５％，Ｉｎ２５．２％，Ｓｎ１７．３％とＢｉ５４％，Ｉｎ２９．７％，Ｓｎ１６．３％のそれぞれを基準にＢｉ±２％，Ｉｎ及びＳｎ±１％の範囲を除く）、（６）１０％≦Ｓｎ≦１８％，３７％≦Ｉｎ≦４３％，残Ｂｉ、（７）２５％＜Ｓｎ≦６０％，２０％≦Ｉｎ＜５０％，１２％＜Ｂｉ≦３３％、（８）（１）〜（７）の何れか１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（９）３３％≦Ｓｎ≦４３％，０．５％≦Ｉｎ≦１０％，残Ｂｉ、（１０）４７％≦Ｓｎ≦４９％，５１％≦Ｉｎ≦５３％の１００重量部にＢｉを３〜５重量部を添加、（１１）４０％≦Ｓｎ≦４６％，７％≦Ｂｉ≦１２％，残Ｉｎ、（１２）０．３％≦Ｓｎ≦１．５％，５１％≦Ｉｎ≦５４％，残Ｂｉ、（１３）２．５％≦Ｓｎ≦１０％，２５％≦Ｂｉ≦３５％，残Ｉｎ、（１４）（９）〜（１３）の何れか１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（１５）１０％≦Ｓｎ≦２５％，４８％≦Ｉｎ≦６０％，残Ｂｉを１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加の何れかを使用でき、Ｂｉ−Ｓｎ−Ｓｂ系合金の組成には例えば（１６）３０％≦Ｓｎ≦７０％，０．３％≦Ｓｂ≦２０％，残Ｂｉ、（１７）（１６）の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、Ｉｎ−Ｓｎ系合金の組成が（１８）５２％≦Ｉｎ≦８５％，残Ｓｎ、（１９）（１８）の１００重量部にＡｇ、Ａｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加の何れかを使用でき、Ｉｎ−Ｂｉ系合金の組成には例えば（２０）４５％≦Ｂｉ≦５５％，残Ｉｎ、（２１）（２０）の組成の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加の何れかを使用でき、Ｂｉ−Ｓｎ系合金の組成には例えば（２２）５０％＜Ｂｉ≦５６％，残Ｓｎ、（２３）（２２）の組成の１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加の何れかを使用でき、Ｉｎ系合金の組成には例えば（２４）Ｉｎの１００重量部にＡｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（２５）９０％≦Ｉｎ≦９９．９％，０．１％≦Ａｇ≦１０％の１００重量部にＡｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加、（２６）９５％≦Ｉｎ≦９９．９％，０．１％≦Ｓｂ≦５％の１００重量部にＡｕ、Ｂｉ、Ｃｕ、Ｎｉ、Ｐｄ、Ｐｔ、Ｇａ、Ｇｅ、Ｐの１種または２種以上を合計０．０１〜７重量部添加の何れかを使用できる。
使用するヒューズエレメントの合金の比抵抗が従来ヒューズエレメント合金のα倍であるとすると、ヒューズエレメントの抵抗値を従来ヒューズエレメントと同一抵抗値とするように、ヒューズエレメントの長さを従来ヒューズエレメントの長さＬに対し、Ｌ／αとしてある。従って、ヒューズエレメントの長さがＬ（α−１）／αだけ短くされ、中間電極２０のヒューズエレメント接続部位の巾Ｗを狭くし、その両側に前記所定の絶縁距離ｄ1及びｄ2を隔てて第１電極２１及び第２電極２２を配設してある。
上記のようにヒューズエレメント４の体積が（α−１）／α倍とされて１／αだけ減少されるから、中間電極のヒューズエレメント接続部位の巾の減少により中間電極２０の表面積が小さくされるにもかかわらず、溶融ヒューズエレメントの溶融合金量の減少のために溶融合金の濡れ拡り範囲がそれだけ狭くなる結果、中間電極の面積不足に起因する濡れ拡がり未完結に基づく動作不良をよく排除できる。
【００２０】
特に、膜抵抗に対するオーバコートを設けている場合は、上記中間電極の狭巾化のもとでも中間電極の有効濡れ距離の広大化を図ることができ、良好な動作性能を保証できる。
図２の（イ）及び（ロ）〔図２の（イ）のロ−ロ断面図〕に示すように、中間電極２０の膜抵抗側片端部２０１で膜抵抗３の一端部３１を覆い、中間電極片端部２０１上をオーバーコート５の中間電極側一端部５１で覆い、中間電極２０のヒューズエレメント接続部位から前記オーバーコート５の一端５１ｅまでの距離Ｌ1を、同部位から膜抵抗一端３１ｅまでの距離Ｌ2に対し、Ｌ1＞Ｌ2−３００μｍとしてある。
【００２１】
図２の（イ）において、中間電極２０のヒューズエレメント接続部位の巾（Ｗ）を第１電極２１、第２電極２２それぞれのヒューズエレメント接続部位の巾Ｗ1、Ｗ2より狭くし、Ｗ＜Ｗ1，Ｗ2とし（通常、Ｗ1＝Ｗ2）としてある。また、第１電極２１と中間電極２０との間隔ｄ１及び第２電極２２と中間電極２０との間隔ｄ２並びに第３電極２３のリード導体取付け部２３０と第２電極２２との間隔ｄは、ヒューズエレメント４の分断によりそれらの間が電気的に遮断されてその遮断間に回路電圧が作用しても、それらの各間隔での絶縁を保証できるように所定距離に設定してあり、通常ｄ１＝ｄ２＜ｄとしてある。
図２の（イ）（ロ）において、４はヒューズエレメントであり、図１に示した実施例と同様に第１電極２１と第２電極２２間に溶接等により接続し、中間部を中間電極２０に溶接等により接続してある。６はヒューズエレメント４に塗布したフラックスである。
リード導体や絶縁被覆体は図には現れていないが、これらの構成は実施例１に実質的に同じである。
【００２２】
図２の（ハ）は図２の（イ）のロ−ロ断面と同じ断面位置の断面図により従来例を示している。
図２の（イ）及び（ロ）〔図２の（イ）におけるロ−ロ断面図〕と従来例の同断面を示す図２の（ハ）とにおいて、膜抵抗一端３１ｅ（３１ｅ’）からヒューズエレメントまでの距離が等しいとし、その距離をＬ２とする。
而るに、従来例では抵抗膜３’を封止するために、オーバーコート５’の四方を抵抗膜３’の四方縁端を越え突出させており、その突出代が通常３００〜１０００μmとされているから、オーバーコート一端３１ｅ’から中間電極２０’のヒューズエレメント接続部位までの距離は最大でも、Ｌ2−３００μｍである。
従って、請求項３によれば、オーバーコート一端からヒューズエレメントまでの有効濡れ距離が従来例よりも長く、その有効濡れ距離の増加による有効濡れ面積の増大のために、中間電極２０のヒューズエレメント接続部位の巾の減少により中間電極２０の有効濡れ面積が低減されても、前記有効濡れ面積の低減をそれだけ軽度にとどめ得、このことと前記したヒューズエレメント体積量が少なくなることによることとの相乗効果で分断動作性能を充分に保証できる。
【００２３】
上記において、オーバーコート一端５１ｅからヒューズエレメント４までの距離Ｌ１がヒューズエレメント４から抵抗膜一端３１ｅまでの距離（基準距離）Ｌ２より小であっても（Ｌ１＜Ｌ２であっても）、Ｌ１＞Ｌ２−３００μｍの条件を満たす以上、前記した通りヒューズエレメント４の球状化分断性能の高揚に寄与させ得るが、
【数１】
Ｌ１≧Ｌ２
とすれば、中間電極における溶融合金が膜抵抗側に向け濡れ拡がることに対する有効距離Ｌ１をそれだけ長くできるから、Ｌ１≧Ｌ２とすることが望ましい。
【００２４】
図２の（イ）及び（ロ）に示す実施例では、抵抗膜一端部３１の封止性能が中間電極片端部２０１とオーバーコート一端部５１との重畳界面に依存し、中間電極及び抵抗膜の配置・寸法が固定されており、その重畳界面距離Ｌ３が中間電極片端２０１ｅに対するオーバーコート一端５１ｅの突出代により与えられるが、この重畳界面距離Ｌ３を余り長くすると、中間電極２０における溶融合金が膜抵抗側に向け濡れ拡がることに対する有効距離Ｌ１が減少して球状化分断性能の向上効果が低減されるから、通常、前記の重畳界面距離Ｌ３は６００μｍ以下とされる。
【００２５】
前記保護素子の製造は、（ａ）膜抵抗パターンのメッシュスクリーンを当接して膜抵抗を印刷し次で焼き付ける工程、（ｂ）電極パターンのメッシュスクリーンを当接して電極を印刷し次で焼き付ける工程、（ｃ）オーバーコート用メッシュスクリーンを当接してオーバーコートを印刷し次で焼き付ける工程、（ｄ）オーバーコート印刷・焼付け工程の前または後で必要に応じてトリミングにより膜抵抗の抵抗値を所定値に設定する工程、（ｅ）第１〜第２電極間に可溶合金片を連結し次いでフラックスを塗布する工程、（ｆ）第１〜３電極にリード導体をスポット溶接により接続する工程、（ｇ）ケースカバーで封止する工程の工程順で進められ、リード導体の接続に時間を要して可溶合金片に熱的影響を及ぼす畏れのあるもの、例えばはんだ付けを用いる場合は、第１〜３電極にリード導体を接続する工程を、第１〜第２電極に可溶合金片を連結し次いでフラックスを塗布する工程の前とすることが安全である。
【００２６】
上記した保護素子の動作後では、動作前に可溶合金片で電気的に導通されていた電極間が電気的に遮断され、その電極間に回路電圧が作用する結果、その電極間距離が短い箇所では、閃絡による再導通が発生する畏れがある。この再導通を防止するために、図３に示すように、膜抵抗に連結された中間電極２０または第３電極２３と他の電極（第１電極や第２電極）とが対向する部分の少なくとも一部の電極縁端部に沿いオーバーコート５の延設部５１１，５１２または５１３を形成し、前記閃絡を防止するように絶縁補強することができる。
【００２７】
図４の（イ）は本発明に係る保護素子の前記とは別の実施例を示す図面、図４の（ロ）は図４の（イ）におけるロ−ロ断面図である。
図４の（イ）及び（ロ）において、１は耐熱性の絶縁基板例えばセラミックス基板である。３は絶縁基板上に設けた膜抵抗であり、前記した通り抵抗ペーストの印刷・焼付けにより設けてある。５は膜抵抗３に対するオーバーコートであり、オーバーコート一端５１ｅから抵抗膜３の一端部３１を所定の距離ａだけ突出させ、オーバーコート一端５２ｅから抵抗膜３の他端部３２を所定の距離ｂだけ突出させてある。
図４の（イ）において、２０は中間電極、２１は第１電極、２２は第２電極、２３は第３電極であり、中間電極２０のヒューズエレメント接続部位の巾Ｗを第１電極２１、第２電極２２それぞれのヒューズエレメント接続部位の巾Ｗ1、Ｗ2より狭くし、Ｗ＜Ｗ1，Ｗ2（通常Ｗ1＝Ｗ2）としてある。また、第１電極２１と中間電極２０との間隔ｄ１及び第２電極２２と中間電極２０との間隔ｄ２、第３電極２３のリード導体取付け部２３０と第２電極２２との間隔ｄを、ヒューズエレメント４の分断によりそれらの間が電気的に遮断されてその遮断間に回路電圧が作用しても、それらの各間隔での絶縁を保証できるように各間隔を所定距離以上に設定してあり、通常ｄ１＝ｄ２＜ｄとしてある。
図４の（イ）（ロ）において、第３電極２３は膜抵抗３に前記の突出代ｂで接触させて電気的に接続してある。中間電極２０の片端部（膜抵抗側端部）２０１をオーバーコート５の一端５１ｅを越えるように位置させてあり、中間電極２０は膜抵抗３に前記抵抗膜一端部３１の突出代ａで接触させて電気的に接続してある。
４はヒューズエレメントであり、図１に示した実施例と同様に第１電極２１と第２電極２２間に溶接等により接続し、中間部を中間電極２０に溶接等により接続してある。６はヒューズエレメント４に塗布したフラックスである。
リード導体や絶縁被覆体は図には現れていないが実施例１に実質的に同じ構成である。
【００２８】
図４の（ハ）は、図４の（ロ）の断面と同じ位置の断面にて従来例を示している。
図４の（ロ）及び（ハ）において、膜抵抗一端の位置３１ｅ，３１ｅ’は両者同じであり、ヒューズエレメント４，４’からこの位置までの距離Ｌ２は同一寸法である。また膜抵抗一端部３１（３１’）と中間電極片端部２０１（２０１’）との間の接触代ａを同じにしてその間の接触電気抵抗を等しくしてある。
従来例では、既述した通り、オーバーコート一端５１ｅ’を膜抵抗一端３１ｅ’より少なくとも３００μｍ突出させているから、溶融した可溶合金の膜抵抗側への濡れ拡がりに対する有効距離は最大でもＬ２−３００μｍである。これに対し、請求項４に係る抵抗体付き温度ヒューズにおいては、中間電極２０の片端部２０１をオーバーコート一端５１ｅを越えて位置させており、溶融した可溶合金の膜抵抗側への濡れ拡がりに対する有効距離を従来の抵抗体付き温度ヒューズの有効距離Ｌ２−３００μｍより大にできる。
従って、中間電極のヒューズエレメント接続部位の巾の減少により中間電極の有効濡れ面積が低減されても、請求項４によれば、オーバーコート一端からヒューズエレメントまでの上記有効濡れ距離の増加による有効濡れ面積の増大で、前記有効濡れ面積の低減をそれだけ軽度にとどめ得、このことと前記したヒューズエレメント体積量が少なくなることによることとの相乗効果で分断動作性能を充分に保証できる。
【００２９】
図４に示す保護素子の製造は、（ａ）膜抵抗パターンのメッシュスクリーンを当接して膜抵抗を印刷し次で焼き付ける工程、（ｂ）オーバーコート用メッシュスクリーンを当接してオーバーコートを印刷し次で焼き付ける工程、（ｃ）電極パターンのメッシュスクリーンを当接して電極を印刷し次で焼き付ける工程、（ｄ）必要に応じて、トリミングにより膜抵抗の抵抗値を所定値に設定する工程、（ｅ）第１〜第２電極にヒューズエレメントを連結し次いでフラックスを塗布する工程、（ｆ）第１〜第３電極にリード導体をスポット溶接により接続する工程、（ｇ）ケースカバーで封止する工程の工程順で進められ、リード導体の接続に、時間を要しヒューズエレメントに熱的悪影響を及ぼす畏れのあるもの、例えばはんだ付けを用いる場合は、各電極にリード導体を接続する工程を、電極にヒューズエレメントを連結し次いでフラックスを塗布する工程の前とすることが安全である。
【００３０】
中間電極のヒューズエレメント接続部位の狭巾化にもかかわらず、中間電極の有効濡れ面積を増大するための別の手段として、中間電極のヒューズエレメント接続部位とは別の部分を図５の（イ）や（ロ）に示すように膨出２０１させ、この膨出のもとでも中間電極２０と第１電極２１との間の絶縁距離及び中間電極２０と第２電極２２との間の絶縁距離を所定の絶縁距離に保持するように第１電極２１や第２電極２２を前記膨出に応じ凹ませるか[図５の（イ）]、または後退２１１、２２１させてある[図５の（ロ）]。
【００３１】
上記何れの実施例においても、第３電極２３のリード導体７３の断面積を小さくすれば、膜抵抗３の通電発生熱の当該リード導体７３を経ての熱伝導流出を抑制して膜抵抗３の発熱速度を迅速化でき、保護素子の動作速度を一層に速くできるので、第３電極に接続するリード導体の断面積を、他のリード導体（第１電極、第２電極に接続するリード導体）に対し、０．８〜０．５倍程度とすることが好ましい。
この場合、全リード導体の断面を高さが等しい四角形とし、断面積の減少を巾を狭めることにより行えば、全リード導体の高さを等しくし得てカバー用の絶縁板または絶縁ケースを載置したときに傾きなく水平にでき、また全リード導体を打ち抜きによるリードフレームから容易に製作できる。
【００３２】
本発明に係る抵抗体付き温度ヒューズによれば、機器の異常に対する前兆を検出し、この検出に伴い膜抵抗を通電発熱させ、この発生熱でヒューズエレメントを溶断させて機器への通電を遮断することができ、この通電遮断により膜抵抗への通電も遮断される。例えば、リチウムイオン２次電池の充電時、過充電時に発生する電圧上昇を検出し、この検出に伴い膜抵抗を通電発熱させ、この発生熱でヒューズエレメントを溶断させて２次電池を充電器から遮断することができる。
【００３３】
図６は上記実施例の抵抗体付き温度ヒューズを用いた２次電池の保護回路を示している。
図６において、Ｓは充電器、Ａはリチウムイオン二次電池である。Ｂは検出動作回路部を示し、ツエナダイオードＤを抵抗Ｒを経てトランジスタＴｒのベースに接続し、エミッタを接地し、ツエナダイオードＤの正極側を回路の高電圧側に接続してある。Ｃは上記実施例の保護素子を示し、第１電極２１と第２電極２２とを充電器Ｓと２次電池Ａ間に接続し、第３電極２３を前記トランジスタＴｒのコレクタに接続してある。
上記ツエナダイオードＤの降伏電圧を２次電池の過充電時に発生する電圧上昇に対し低く設定してあり、過充電により電圧が上昇すると、トランジスタＴｒにベース電流が流れ、大きなコレクタ電流が流れて膜抵抗３が発熱し、この発生熱が中間電極２０を経てヒューズエレメント４に伝達され、ヒューズエレメント４が溶融され、溶融合金４が既溶融フラックスの活性作用を受けつつ中間電極２０及びその両側の第１電極２１と第２電極２２に濡れ拡がって中間電極２０と第１電極２１との間及び中間電極２０と第２電極２２との間で分断されると共に膜抵抗３が電池から遮断される。
本発明に係る保護素子においては、ヒューズエレメントの融点を機器、例えば上記２次電池の保護温度（８０℃〜１２０℃における所望の温度）に選定し、保護素子を実質的に機器温度に追従して昇温させ得るように機器に熱的に接触して取り付ければ、機器の通電を保護温度で遮断でき、保護温度を越えての機器の異常発熱ひいては火災の発生を未然に防止できる。
【００３４】
本発明に係る保護素子は、上記した膜抵抗を省き、ヒューズエレメントの融点を機器の保護温度に設定し、機器に熱的接触下で取り付け、機器の通電を保護温度で遮断して保護温度を越えての機器の異常発熱ひいては火災の発生を未然に防止する形態で使用することもでき、図７や図８はその使用形態を示している。
図７において、１は耐熱性の絶縁基板例えばセラミックス基板である。２１及び２２は導電ペーストの印刷・焼付けにより設けた第１電極及び第２電極であり、リード導体取付け部２１０及び２２０を備えている。２０は中間電極であり、第１電極２１と第２電極２２との中間に配設してあり、この中間から外れた位置にリード導体取付け部２００を備えている。４は可溶合金からなるヒューズエレメントであり、第１電極２１と第２電極２２間に溶接等により接続すると共に中間を中間電極２０に溶接等により接続してある。中間電極２０のヒューズエレメント接続部位の巾Ｗは第１電極２１、第２電極２２それぞれのヒューズエレメント接続部位の巾Ｗ1、Ｗ2より狭くし、Ｗ＜Ｗ1，Ｗ2としてある。通常、Ｗ1＝Ｗ2とされている。
前記第１電極２１と中間電極２０との間隔ｄ１及び第２電極２２と中間電極２０との間隔ｄ２は、ヒューズエレメント４の分断によりそれらの間が電気的に遮断されてその遮断間に回路電圧が作用しても、それらの各間隔での絶縁を保証できるように各間隔を所定距離以上に設定してあり、通常ｄ１＝ｄ２としてある。
６はヒューズエレメント４に塗布したフラックスである。７０、７１及び７２は中間電極２０〜第２電極２２のそれぞれのリード導体取付け部２００〜２２０に溶接等により接続したリード導体であり、溶接にはスポット抵抗溶接を用いることが好ましい。
８は絶縁被覆体であり、例えば、封止剤例えばエポキシ樹脂を塗着する構成、または封止剤層上に保護プレートを固着した構成、あるいはカバーを基板上に載置し、カバー周囲の枠のリード導体引出孔からリード導体を引出し、接着剤例えばエポキシ樹脂で封止した構成とすることができる。
【００３５】
図８の（イ）及び（ロ）は上記とは別の異なる使用形態を示し、図７に示した実施例に対し、中間電極のヒューズエレメント接続部位とは別の部分を膨出させ、この膨出のもとでも中間電極２０と第１電極２１との間の絶縁距離及び中間電極２０と第２電極２２との間の絶縁距離を所定の絶縁距離に保持するように第１電極２１や第２電極２２を前記膨出に応じ局部的に凹ませるか〔図８の（イ）〕、または後退させてある〔図８の（ロ）〕。
【００３６】
上記何れの実施例においても、リード導体付きとしているが、抵抗体付き温度ヒューズでは、第１電極、第２電極及び第３電極を基板の裏面側に基板側面を経て廻してチップタイプとし、温度ヒューズでは、第１電極、第２電極及び中間電極を基板の裏面側に基板側面を経て廻してチップタイプとすることもできる。
【００３７】
本発明においてオーバーコート材は、絶縁物であり、ガラスコートに限定されず、合成樹脂コート例えばエポキシ樹脂コートも使用できる。
本発明において電極材には、導電粒子とガラスフリットと有機溶剤との混合物からなる焼成タイプの外、導電粒子と熱硬化性樹脂（例えばエポキシ樹脂）と溶剤との混合物からなる熱硬化タイプの使用も可能であり、導電粒子には、銀、パラジウム、金、銅等の金属粒子、カーボン等を使用できる。
本発明において膜抵抗材には、抵抗粒子とガラスフリットと有機溶剤との混合物からなる焼成タイプの外、抵抗粒子と熱硬化性樹脂（例えばエポキシ樹脂）と溶剤との混合物からなる熱硬化タイプの使用も可能であり、抵抗粒子には、金属酸化物粒子例えば酸化ルテニウム粒子を使用できる。その他、Ｔｉ−Ｓｉ系抵抗ペーストの使用も可能である。
フラックスには、天然ロジン、変性ロジン（水添ロジン、不均化ロジン、重合ロジン等）及びこれらの精製ロジンにジエチルアミンの塩酸塩、ジエチルアミンの臭化水素酸塩、アジピン等の有機酸等を添加したものを使用できる。
本発明において絶縁基板には、絶縁性で、かつ電極や膜抵抗の形成に耐え得る耐熱性を有するものであれば特に制限無く使用でき、アルミナセラミックス板のようなセラミックス板、耐熱性プラスチック板、ガラス繊維強化プラスチック板、表面に絶縁膜を有する金属板等を使用できる。
【００３８】
本発明に係る保護素子における絶縁基板のタテ×ヨコ寸法は、通常（４．０〜１０．０）mm×（４．０〜１０．０）mmとされる。電極や膜抵抗の配置パターンや寸法は定格電流や定格電圧に応じて設定される。
定格が１０Ａ×５０Vの場合、中間電極のリード導体接続部位の巾は３００〜４００μm、第１電極と中間電極との間隔や第２電極と中間電極との間隔は３００〜１０００μmとされる。
【００３９】
本発明において、ヒューズエレメントには生体系に有害な元素を含まない合金、例えばＳｎ−Ｉｎ−Ｂｉ系合金を用いることが好ましい。このＳｎ−Ｉｎ−Ｂｉ系合金合金組成の一例としてＳｎ４３〜７０％、Ｉｎ０．５〜１０％、残部Ｂｉについて、液相線温度、比抵抗値を示せば表１の通りである。
ただし、液相線温度はＤＳＣ〔基準試料（不変化）と測定試料を窒素ガス容器内に納め、容器ヒータに電力を供給して両試料を一定の速度で加熱し、測定試料の熱的変化に伴う熱エネルギー入力量の変動を示差熱電対により検出する〕により測定した。
【表１】

比抵抗値が２０μΩcm以上と高いが、本発明によればヒューズエレメントの長さを短くしてヒューズエレメントの抵抗値を通常値におさめ得、良好な動作性能を保証できる。
【００４０】
上記合金の比抵抗値を低減すると共に結晶組織を微細化させ合金中の異相界面を小さくして加工歪や応力の分散性を良くするために、前記の合金組成１００重量部にＡｇ、Ａｕ、Ｃｕ、Ｇａ、Ｇｅ、Ｎｉ、Ｐｄ、Ｐｔ、Ｓｂ、Ｐの少なくとも一種を０．０１〜７重量部添加することができる。添加量を０．０１〜７重量部とする理由は、０．０１重量部未満では効果が非常に不充分であり、７重量部を越えると合金の溶融特性が非常に変化し、例えば動作温度のバラツキを許容範囲におさめ難くなる等の不具合が生じるからである。
【００４１】
【実施例】
作動温度については、実施例と比較例の各試料個数を５０箇とし、０．１アンペアの電流を通電しつつ昇温速度１℃／分のオイルバスに浸漬し、ヒューズエレメント分断による通電遮断時のオイル温度を動作温度とした。
【００４２】
〔比較例１〕
図９に示す従来品であり、絶縁基板１にタテ×ヨコ×厚み寸法が６ｍｍ×６ｍｍ×０．６４ｍｍのアルミナセラミックス板を使用し、膜抵抗３を酸化ルテニウム系抵抗ペーストの印刷・焼付けにより形成し、電極２０〜２３を銀系導電ペーストの印刷・焼付けにより形成した。第１電極２１及び第２電極２２（共にリード導体取付け部を除く）のタテ×ヨコ（巾）寸法を１．７ｍｍ×６００μmとし、中間電極２０のタテ×ヨコ（巾）寸法を１．７ｍｍ×１２００μmとし、第１電極と中間電極との間隔と第２電極と中間電極との間隔を５００μmとした。オーバーコートをガラスペーストの印刷・焼き付けにより形成した。ヒューズエレメントにＳｎ４６．５％−Ｐｂ２９．８％−Ｃｄ１６．７％−Ｉｎ７％、比抵抗値１５μΩcmの合金を使用し、ヒューズエレメント外径を５００μmφ、長さを３．３ｍｍとした。ヒューズエレメントの抵抗値は、２５ｍΩである。第１電極及び第２電極のそれぞれのリード導体取付け部に厚み×巾が３００μm×１０００μmのＳｎメッキ銅リード導体を、第３電極の中間電極２０のリード導体取付け部に取り付け部厚み×巾が３００μm×１０００μm，狭巾部厚み×巾が３００μm×７００μmのＳｎメッキ銅リード導体を接続し、これらの上にカバーとしてタテ×ヨコ×厚み寸法が４ｍｍ×４ｍｍ×０．６４ｍｍのアルミナセラミックス板を載置し、このカバー板と基板との間をエポキシ樹脂で封止した。フラックス６にはロジン８０重流部，ステアリン酸２０重量，ジエチルアミン臭化水素酸塩１重量部の組成物を使用した。
動作温度を測定したところ、１３５±２℃であった。
【００４３】
〔実施例〕
比較例１に対し、中間電極の巾寸法を３００μmとし、ヒューズエレメントにＢｉ５２％−Ｓｎ４６％−Ｉｎ２％、比抵抗値３４μΩcmの合金を使用し、ヒューズエレメントの長さを２．４ｍｍとし、ヒューズエレメントの抵抗値を比較例１とほぼ同一値とするためにヒューズエレメントの外径を６４０μmφと太くした以外、比較例１に同じとした。
動作温度を測定したところ、１３６±２℃であった。
【００４４】
〔比較例２〕
ヒューズエレメントに実施例１と同じくＢｉ５２％−Ｓｎ４６％−Ｉｎ２％、比抵抗値３４μΩcmの合金を使用した。電極寸法・配置・ヒューズエレメント長さを比較例１のままにしてヒューズエレメントの抵抗値を比較例１や実施例とほぼ同一値にするためにヒューズエレメントの外径を比較例１の１．５倍（√３４／√１５倍）の７５０μmφとした。
動作温度を測定したところ、比較例１よりも相当に高くバラツキも大であって１４１±５℃であった。
実施例と比較例１との比較から明らかなように、本発明によれば、中間電極の巾を１２００μmから３００μmにも狭くしたにもかかわらず同等の作動性能を維持でき、保護素子の小型化を図ることができる。
比較例２では、ヒューズエレメント体積に対する中間電極面積の影響のために可溶合金の溶融後、分断までに時間がかかった結果、動作性能が低下したと推定されるが、実施例では中間電極の狭巾化にもかかわらず良好な動作性能を呈した。
【００４５】
【発明の効果】
本発明に係る保護素子によれば、ヒューズエレメントを短くしてヒューズエレメントを所定抵抗値以下に保持することを可能にしており、ヒューズエレメントの短縮に応じて保護素子寸法の小型化を図ることができる。また、ヒューズエレメントの比抵抗値のアップに対しては、その比抵抗値の増加に応じヒューズエレメントの長さを短くすることによりヒューズエレメントの抵抗値を所定値に保持できるから、従来におけるヒューズエレメントの長さをそのままにしてヒューズエレメントの外径増大によりヒューズエレメントの抵抗値を所定値に保持する場合に較べてヒューズエレメントの体積量を少なくでき、このヒューズエレメント体積量の減少は比抵抗値が大きくなるほど顕著になるから、ヒューズエレメントの比抵抗値が大きくなるほどヒューズエレメント体積量減少による動作性能の向上を図ることができる。
【００４６】
本発明に係る保護素子によれば、前記の効果を抵抗体付き温度ヒューズにおいて得ることができる。
【００４７】
本発明に係る保護素子によれば、基板の片面に膜抵抗及びヒューズエレメント並びに中間電極を有し、膜抵抗の一端部を中間電極の片端部に連結し、該膜抵抗の片端から所定の距離を隔てた中間電極部位にヒューズエレメントを接合し、膜抵抗上にオーバーコートを施す抵抗体付き温度ヒューズにおいて、従来の抵抗体付き温度ヒューズに対し、中間電極を含めた電極を印刷・焼付けする工程と膜抵抗を印刷・焼付けする工程とを交互に入れ換え、かつオーバーコート一端とヒューズエレメントとの間隔を広げるようにオーバーコートの印刷寸法を調整するだけで、中間電極での溶融合金に対する濡れ有効距離を長くでき、中間電極の狭巾化のもとでも良好な動作性能を保証できる抵抗体付き温度ヒューズを提供できる。
【００４８】
本発明に係る保護素子によれば、基板の片面に膜抵抗及びヒューズエレメント並びに中間電極を有し、膜抵抗の一端部が中間電極の片端部に連結され、該膜抵抗の片端から所定の距離を隔てた中間電極部位にヒューズエレメントが接合され、膜抵抗上にオーバーコートが施され、膜抵抗一端部がオーバーコート一端より突出し、中間電極片端部が前記突出した膜抵抗一端部及びオーバーコート一端部を覆っているから、中間電極片端部がオーバーコート一端部を覆う寸法分が長くなることにより中間電極での溶融合金に対する濡れ有効距離を長くでき、中間電極の狭巾化のもとでも良好な動作性能を保証できる抵抗体付き温度ヒューズを提供できる。
【００４９】
本発明に係る保護素子によれば、ヒューズエレメントの短尺化を保有しつつ中間電極の濡れ面積を大きくできるから、中間電極の狭巾化のもとでものもとでも良好な動作性能を保証できる抵抗体付き温度ヒューズを提供できる。
【００５０】
本発明に係る保護素子によれば、ヒューズエレメントの分断時に電極間に作用する電圧に対し絶縁補強でき、分断後の再導通防止を確保でき、安定な遮断を保証できる。
【００５１】
本発明に係る保護素子によれば、膜抵抗の昇温速度を迅速化でき、抵抗体付き温度ヒューズの動作速度を速くできる。
【図面の簡単な説明】
【図１】本発明に係る保護素子の一実施例を示す図面である。
【図２】前記実施例の一部を示す図面である。
【図３】前記実施例の他の一部を示す図面である。
【図４】本発明に係る保護素子の別実施例の一部を示す図面である。
【図５】本発明に係る保護素子の上記とは別の実施例を示す図面である。
【図６】本発明に係る保護素子の使用方法を示す回路図である。
【図７】本発明に係る保護素子の一使用形態例を示す回路図である。
【図８】本発明に係る保護素子の別使用形態例を示す回路図である。
【図９】従来の保護素子を示す図面である。
【図１０】従来の上記とは別の保護素子を示す図面である。
【符号の説明】
１絶縁基板
２０中間電極
２１第１電極
２２第２電極
２３第３電極
３膜抵抗
３１膜抵抗一端部
３１ｅ膜抵抗一端
４ヒューズエレメント
５オーバーコート
５１オーバーコート一端部
５１ｅオーバーコート一端
６フラックス
８絶縁被覆体[0001]
BACKGROUND OF THE INVENTION
  The present inventionIsThe present invention relates to a protection element such as a thermal fuse with a resistor.
[0002]
[Prior art]
  A thermal fuse with a resistor has a fuse element made of a fusible alloy, includes a resistor that blows the fuse element by energization heat generation, and is used in combination with an abnormality detection circuit. An abnormal voltage is detected by an abnormality detection circuit, and the resistor is energized and heated by this detection, and the fuse element is blown by the generated heat to cut off the energization of the equipment.
  Also, the melting point of the fuse element can be set to the allowable temperature of the device, and when the device reaches the allowable temperature, the fuse element can be blown to be used for preventing abnormal heat generation of the device and fire.
[0003]
  FIG. 9 (a) is a drawing showing an example of a conventional thermal fuse with a resistor, and FIG. 9 (b) is a cross-sectional view of FIG. 9 (b).
  In FIG. 9, 1 'is an insulating substrate such as a ceramic substrate, and 20' to 23 'are electrodes provided on the insulating substrate by printing and baking of a conductive paste. A fuse element 4 'is connected between the first electrode 21' and the second electrode 22 'by welding or the like, and is also joined to the intermediate electrode 20'. Reference numeral 3 'denotes a film resistor connected between the third electrode 23' and the intermediate electrode 20 ', which is provided by printing and baking of a resistance paste. Reference numeral 5 ′ denotes an overcoat for the film resistor 3 ′, which is provided by printing and baking a glass paste, and is generally an outer layer that is approximately 300 μm to 1000 μm larger than the outer layer of the film resistor 3 ′. 6 'is a flux applied to the fuse element. Reference numeral 8 'denotes an insulating cover.
[0004]
  The operation mechanism of the temperature-provided thermal fuse is as follows.
  That is, normally, the membrane resistance is not energized, and the fuse element is inserted between the device and the power source and energized. When an abnormality occurs, the membrane resistance is energized and heated, the fuse element is melted by this generated heat, and the molten alloy is spheroidized and divided by wetting and spreading to the electrode in the presence of pre-melted flux, and this division interrupts the conduction of the membrane resistance. The non-return cut-off is terminated by cooling and solidifying the divided alloy.
  Also, if the melting point of the fuse element is set to the allowable temperature of the device, the fuse element is melted when the device reaches almost the allowable temperature, and the molten alloy coexists with the molten flux due to wetting and spreading to the electrode. The spheroidization is divided, the energization to the device is cut off by this division, the temperature of the device is lowered, and the non-return cut-off is terminated by the cooling and solidification of the divided alloy.
[0005]
  FIG. 10 shows a thermal fuse in which film resistance is omitted with respect to the thermal fuse with a resistor, which is used in the latter usage form.
[0006]
[Problems to be solved by the invention]
  Both the temperature-provided fuse and the temperature fuse operate by wetting and spreading to the electrodes of the melted fuse element. Conventionally, the molten alloy wets and spreads from both sides of the intermediate electrode 20 ′, so that the intermediate electrode 20 The width W ′ is made wider than the width W1 ′ of the first electrode 21 and the width W2 ′ of the second electrode 22.
  Conventionally, a fusible alloy containing lead as a main component has been used for a fuse element of a thermal fuse or a thermal fuse with a resistor. However, lead is harmful to biological systems, and it has been strongly demanded to use an alloy composition that does not contain lead and other harmful elements as well as other electrical components for fuse elements.
  As such an alloy composition, for example, a Sn—In—Bi alloy is promising, but has a high specific resistance value. For example, conventional fuse element alloy Sn 46.5% -Pb 29.8% -Cd 16.7% -In 7% with an operating temperature of 135 ° C., and a specific resistance value of 15 μΩcm, fuse element alloy Bi 52% -Sn 46% with almost the same operating temperature. At -In2%, the specific resistance is 34 μΩcm, which is more than twice.
[0007]
  The resistance value of the fuse element of a thermal fuse or a thermal fuse with a resistor must be kept below a certain value due to restrictions on internal resistance due to load and self-heating. This is dealt with by increasing the element diameter.
  However, an increase in the fuse element diameter leads to an increase in the amount of the molten alloy, resulting in a decrease in the spheroidizing performance. To prevent this, the electrode area must be increased, and the temperature with the temperature fuse or resistor is increased. Increase in fuse size is inevitable.
[0008]
  It is an object of the present invention to have the intermediate electrodeRuIn a temperature-equipped fuse with a resistor, it is intended to ensure a good split operation performance even if the specific resistance value of the fuse element is high.
  A further object of the present invention is to reduce the size of a thermal fuse having an intermediate electrode or a thermal fuse with a resistor in addition to the above object.
[0009]
[Means for Solving the Problems]
The protection element according to claim 1 includes a first electrode, a second electrode, and a third electrode, an intermediate electrode between the first electrode and the second electrode, and each end of the fuse element made of a fusible alloy. The fuse element is connected to the first electrode and the second electrode, the middle part of the fuse element is connected to the intermediate electrode, the film resistance is connected between the intermediate electrode and the third electrode, and the fused fuse element is melted in operation. The fuse element is divided by wetting and spreading to each of the first electrode and the second electrode of the alloy and the intermediate electrode, and in order to ensure insulation between the first electrode and the second electrode and the intermediate electrode after the division. They are separated by a predetermined insulation distance, and the width of the fuse element connection portion of the intermediate electrode is narrower than the width of the fuse element connection portion of each of the first electrode and the second electrode.In the protective element, the fuse element and the membrane resistance are provided on one side of the insulating substrate, an overcoat is provided for the membrane resistance, the membrane resistance side one end portion of the intermediate electrode covers one end portion of the membrane resistance, and one end of the overcoat on the intermediate electrode side The distance L from the fuse element connection part of the intermediate electrode to the one end of the overcoat 1 Is the distance L from the same part to one end of the membrane resistance. 2 On the other hand, L 1 > L 2 -300 μmIt is characterized by that.
[0010]
The protection element according to claim 2 includes a first electrode, a second electrode, and a third electrode, an intermediate electrode between the first electrode and the second electrode, and each end of the fuse element made of a fusible alloy. The fuse element is connected to the first electrode and the second electrode, the middle part of the fuse element is connected to the intermediate electrode, the film resistance is connected between the intermediate electrode and the third electrode, and the fused fuse element is melted in operation. The fuse element is divided by wetting and spreading to each of the first electrode and the second electrode of the alloy and the intermediate electrode, and in order to ensure insulation between the first electrode and the second electrode and the intermediate electrode after the division. They are separated by a predetermined insulation distance, and the width of the fuse element connection portion of the intermediate electrode is narrower than the width of the fuse element connection portion of each of the first electrode and the second electrode.In the protective element, the fuse element and the membrane resistance are provided on one surface of the insulating substrate, an overcoat for the membrane resistance is provided, one end of the membrane resistor protrudes from one end of the overcoat, and one end of the intermediate electrode from which one end of the intermediate electrode protrudes And covering one end of the overcoat.
[0011]
According to a third aspect of the present invention, in the protective element according to the first or second aspect, the fuse element has a specific resistance value of 20 μΩcm or more.
[0012]
The protection element according to claim 4 is the protection element according to any one of claims 1 to 3, wherein the soluble alloy is an In-Sn-Bi alloy, a Bi-Sn-Sb alloy, an In-Sn alloy, or In-Bi. It is any of an Al alloy, Bi-Sn alloy, and In alloy
.
[0013]
The protection element according to claim 5 is the protection element according to claim 4, wherein the composition of the In—Sn—Bi alloy is (1) 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, and the remaining Bi. (2) 25% ≦ Sn ≦ 40%, 50% ≦ In ≦ 55%, remaining Bi, (3) 25% <Sn ≦ 44%, 55% <In ≦ 74%, 1% ≦ Bi <20%, (4) 46% <Sn ≦ 70%, 18% ≦ In <48%, 1% ≦ Bi ≦ 12%, (5) 5% ≦ Sn ≦ 28%, 15% ≦ In <37%, remaining Bi (however, Bi57.5%, In25.2%, Sn17.3% and Bi54%, In29.7%, and Sn16.3%, except for the range of Bi ± 2%, In and Sn ± 1%), (6) 10% ≦ Sn ≦ 18%, 37% ≦ In ≦ 43%, remaining Bi, (7) 25% <Sn ≦ 60%, 20% ≦ In <50%, 1 2% <Bi ≦ 33%, (8) One or two of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P in 100 parts by weight of any one of (8) (1) to (7) 0.01 to 7 parts by weight in total, (9) 33% ≦ Sn ≦ 43%, 0.5% ≦ In ≦ 10%, remaining Bi, (10) 47% ≦ Sn ≦ 49%, 51% ≦ 3 to 5 parts by weight of Bi are added to 100 parts by weight of In ≦ 53%, (11) 40% ≦ Sn ≦ 46%, 7% ≦ Bi ≦ 12%, remaining In, (12) 0.3% ≦ Sn ≦ 1.5%, 51% ≦ In ≦ 54%, remaining Bi, (13) 2.5% ≦ Sn ≦ 10%, 25% ≦ Bi ≦ 35%, remaining In, (14) (9) to (13 1) or 100 parts by weight of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P or a total of 0.01 to 7 parts by weight, (15) 1 % ≦ Sn ≦ 25%, 48% ≦ In ≦ 60%, the remaining Bi is 100 parts by weight, and one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P is added Addition of 0.01 to 7 parts by weight, composition of Bi-Sn-Sb alloy is (16) 30% ≦ Sn ≦ 70%, 0.3% ≦ Sb ≦ 20%, remaining Bi, (17) (16) One to two or more of Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge, and P are added to 100 parts by weight, and the composition of the In-Sn alloy is (18). 52% ≦ In ≦ 85%, the remaining Sn, (19) (18) is added to one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P in 100 parts by weight Addition of 0.01 to 7 parts by weight, composition of In-Bi alloy is (20) 45% ≦ Bi ≦ 55%, remaining In, (21) ( 0) The composition of 1 to 2 parts of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P is added in a total of 0.01 to 7 parts by weight to 100 parts by weight of the composition of 0), Bi-Sn system (22) 50% <Bi ≦ 56%, remaining Sn, (23) One type of Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge, P or 100 parts by weight of (22) or Two or more kinds are added in a total of 0.01 to 7 parts by weight, and the composition of the In-based alloy is (24) 100 parts by weight of In, one kind of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, P or Add two or more kinds in a total of 0.01 to 7 parts by weight, (25) Au, Bi, Cu, Ni, Pd to 100 parts by weight of 90% ≦ In ≦ 99.9%, 0.1% ≦ Ag ≦ 10% , Pt, Ga, Ge, P or one or more of 0.01 to 7 parts by weight in total, (26) 95% ≦ In ≦ 99.9%, 0.1% ≦ Sb ≦ 5% 100 parts by weight of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, P or a total of 0.01 to 7 parts by weight is added.
[0014]
The protective element according to claim 6 is the protective element according to any one of claims 1 to 5, characterized in that the width of the fuse element connecting portion of the intermediate electrode is 300 to 400 μm and the predetermined insulation distance is 300 to 1000 μm. .
[0015]
The protective element according to claim 7 is the protective element according to any one of claims 1 to 6, wherein the width of the intermediate electrode bulges in a portion different from the fuse element connecting portion, and the width of the first electrode and the second electrode is According to the bulging, it is retracted or recessed locally.
[0016]
The protective element according to claim 8 is the protective element according to any one of claims 1 to 7, wherein the fuse element and the film resistance are provided on one surface of the insulating substrate, an overcoat for the film resistance is provided, and the protective element is connected to the film resistance. An overcoat extends along at least a part of an electrode edge of a portion where at least one electrode and another electrode face each other.
[0017]
The protection element according to claim 9 is the protection element according to any one of claims 1 to 8, wherein the cross-sectional area of the lead conductor connected to the third electrode is that of the lead conductor connected to each of the first electrode and the second electrode. The cross-sectional area is 0.8 to 0.5 times.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
  Figure 1The present inventionIt is drawing which shows one Example of the protection element which concerns on this.
In FIG. 1, reference numeral 1 denotes a heat-resistant insulating substrate such as a ceramic substrate. 21, 22, and 23 are a first electrode, a second electrode, and a third electrode provided by printing and baking a conductive paste, and are provided with lead

conductor attachment portions

210, 220, and 230. Reference numeral 20 denotes an intermediate electrode, which is disposed in the middle between the first electrode and the second electrode. The width of the one end 201 on the third electrode 23 side of the intermediate electrode 20 is set to the third electrode 23 (the lead conductor attachment portion 230). (Not included).
  The width W of the fuse element connecting portion of the intermediate electrode 20 is made narrower than the width W1, W2 of the fuse element connecting portion of each of the first electrode and the second electrode, and W <W1, W2. Usually, W1 = W2.
  The distance d1 between the first electrode 21 and the intermediate electrode 20, the distance d2 between the second electrode 22 and the intermediate electrode 20, and the distance d between the lead conductor mounting portion 230 of the third electrode 23 and the second electrode 22 are the fuse element. Even if a circuit voltage acts between the interruptions due to the electrical disconnection, the intervals are set to a predetermined distance so that insulation at each interval can be guaranteed, and usually d1 = D2 <d.
  Reference numeral 3 denotes a film resistor, and one end 31 of the resistance film 3 is connected to one end 201 of the intermediate electrode 20, and the other end 32 of the resistance film 3 is connected to one end 232 of the third electrode 23.
  In FIG. 1, 4 is a fuse element made of a fusible alloy, and is connected between the first electrode 21 and the second electrode 22 by welding or the like, and the middle is connected to the intermediate electrode 20 by welding or the like. Reference numeral 5 denotes an overcoat for the film resistance 3. Reference numeral 6 denotes a flux applied to the fuse element 4. Reference numerals 71 to 73 are lead conductors connected to the respective lead conductor attachment portions 210 to 230 of the first electrode 21 to the third electrode 23 by welding or the like, and it is preferable to use spot resistance welding for welding.
  Reference numeral 8 denotes an insulating covering, for example, a structure in which a sealant such as an epoxy resin is applied, or a structure in which a protective plate is fixed on a sealant layer, or a cover is placed on a substrate and a frame around the cover The lead conductor can be drawn out from the lead conductor lead-out hole and sealed with an adhesive such as an epoxy resin.
[0019]
  In the above, the fuse element 4 includes an In—Sn—Bi alloy, a Bi—Sn—Sb alloy, an In—Sn alloy, an In—Bi alloy, Bi that does not contain elements harmful to biological systems such as lead. -Sn based alloy, In based alloy, etc. can be used.
The composition of the In—Sn—Bi alloy includes, for example, (1) 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, remaining Bi, (2) 25% ≦ Sn ≦ 40%, 50% ≦ In ≦ 55%, remaining Bi, (3) 25% <Sn ≦ 44%, 55% <In ≦ 74%, 1% ≦ Bi <20%, (4) 46% <Sn ≦ 70%, 18% ≦ In <48%, 1% ≦ Bi ≦ 12%, (5) 5% ≦ Sn ≦ 28%, 15% ≦ In <37%, remaining Bi (Bi57.5%, In25.2%, Sn17.3) % And Bi 54%, In 29.7%, and Sn 16.3% except Bi ± 2%, In and Sn ± 1%, respectively) (6) 10% ≦ Sn ≦ 18%, 37% ≦ In ≦ 43%, remaining Bi, (7) 25% <Sn ≦ 60%, 20% ≦ In <50%, 12% <Bi ≦ 33%, (8) What of (1) to (7) One or two or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P are added to 100 parts by weight, and (9) 33% ≦ Sn ≦ 43%, 0.5% ≦ In ≦ 10%, remaining Bi, (10) 47% ≦ Sn ≦ 49%, 51% ≦ In ≦ 53%, 100 parts by weight of Bi and 3 to 5 parts by weight of Bi are added, (11) 40% ≦ Sn ≦ 46%, 7% ≦ Bi ≦ 12%, remaining In, (12) 0.3% ≦ Sn ≦ 1.5%, 51% ≦ In ≦ 54%, remaining Bi, (13 ) 2.5% ≦ Sn ≦ 10%, 25% ≦ Bi ≦ 35%, remaining In, (14) Ag, Au, Cu, Ni, Pd, Pt in 100 parts by weight of any one of (9) to (13) , Sb, Ga, Ge, P, or a total of 0.01 to 7 parts by weight, (15) 10% ≦ Sn ≦ 25%, 48% ≦ In ≦ 60%, remaining Either 100 parts by weight of i, Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P or a total of 0.01 to 7 parts by weight of one or more of Bi, can be used. The composition of the -Sn-Sb alloy is, for example, (16) 30% ≦ Sn ≦ 70%, 0.3% ≦ Sb ≦ 20%, the remaining Bi, (17) 100 parts by weight of (16) with Ag, Au, One or more of Cu, Ni, Pd, Pt, Ga, Ge, and P are added in a total of 0.01 to 7 parts by weight, and the composition of the In—Sn alloy is (18) 52% ≦ In ≦ 85%, One or two or more of Ag, Au, Bi, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P are added to 100 parts by weight of the remaining Sn, (19) and (18) in a total of 0.01 to 7 weights. In addition, the composition of the In-Bi alloy can be, for example, (20) 45% ≦ Bi ≦ 55%. (21) A total of 0.01 to 7 parts by weight of one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P is added to 100 parts by weight of the composition of (20) Any one of the following can be used, and the composition of the Bi-Sn alloy is, for example, (22) 50% <Bi ≦ 56%, the remaining Sn, (23) 100 parts by weight of the composition of (22), Ag, Au, Cu, Any one of Ni, Pd, Pt, Ga, Ge, and P may be added in a total amount of 0.01 to 7 parts by weight, and the composition of the In alloy may be, for example, (24) 100 wt. 0.01 to 7 parts by weight in total of one or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, P are added to the part, (25) 90% ≦ In ≦ 99.9%, Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, P in 100 parts by weight of 0.1% ≦ Ag ≦ 10% One or two or more of these are added in a total of 0.01 to 7 parts by weight, (26) Au, Bi, Cu in 100 parts by weight of 95% ≦ In ≦ 99.9%, 0.1% ≦ Sb ≦ 5% , Ni, Pd, Pt, Ga, Ge, P, or a total of 0.01 to 7 parts by weight of one or more of them can be used.
  Assuming that the specific resistance of the alloy of the fuse element used is α times that of the conventional fuse element alloy, the length of the fuse element is adjusted so that the resistance value of the fuse element is the same as that of the conventional fuse element. For length L, L / α. Accordingly, the length of the fuse element is shortened by L (α-1) / α, the width W of the fuse element connecting portion of the intermediate electrode 20 is narrowed, and the predetermined insulation distances d1 and d2 are separated on both sides thereof. A first electrode 21 and a second electrode 22 are provided.
  As described above, the volume of the fuse element 4 is set to (α-1) / α times and is reduced by 1 / α. Therefore, the surface area of the intermediate electrode 20 is reduced by reducing the width of the fuse element connecting portion of the intermediate electrode. In spite of this, the range of molten alloy wetting and spreading is narrowed by reducing the amount of molten alloy in the molten fuse element, and as a result, malfunction due to incomplete spreading due to insufficient area of the intermediate electrode is well eliminated. it can.
[0020]
SpecialIn addition,When an overcoat for film resistance is provided, the effective wetting distance of the intermediate electrode can be increased even when the intermediate electrode is narrowed, and good operating performance can be guaranteed.
FIG.As shown in (a) and (b) of FIG. 2 (b), the film resistance side one end 201 of the intermediate electrode 20 covers one end 31 of the film resistor 3, and the intermediate electrode One end portion 201 is covered with the intermediate electrode side one end portion 51 of the overcoat 5, and the distance L1 from the fuse element connecting portion of the intermediate electrode 20 to the one end 51e of the overcoat 5 is the distance from the same portion to one end of the membrane resistance 31e. For L2, L1> L2−300 μm.
[0021]
  In FIG. 2A, the width (W) of the fuse element connecting portion of the intermediate electrode 20 is made narrower than the width W1, W2 of the fuse element connecting portion of each of the first electrode 21 and the second electrode 22, and W <W1, W2 is set (usually W1 = W2). Further, the distance d1 between the first electrode 21 and the intermediate electrode 20, the distance d2 between the second electrode 22 and the intermediate electrode 20, and the distance d between the lead conductor mounting portion 230 of the third electrode 23 and the second electrode 22 are the fuses. Even if a circuit voltage is applied between the elements when they are electrically disconnected by the division of the element 4, the distance is set to a predetermined distance so as to ensure insulation at each interval. Usually, d1 = d2 <d.
  2A and 2B, reference numeral 4 denotes a fuse element, which is connected by welding or the like between the first electrode 21 and the second electrode 22 in the same manner as in the embodiment shown in FIG. 20 is connected by welding or the like. Reference numeral 6 denotes a flux applied to the fuse element 4.
  Although the lead conductor and the insulation coating do not appear in the drawing, their configurations are substantially the same as those in the first embodiment.
[0022]
  FIG. 2C shows a conventional example by a cross-sectional view at the same cross-sectional position as the roll cross section of FIG.
  2 (a) and 2 (b) (roll cross-sectional view in FIG. 2 (b)) and FIG. 2 (c) showing the same cross section of the conventional example, from the membrane resistance one end 31e (31e ′) Assume that the distances to the fuse elements are equal, and that the distance is L2.
  Thus, in the conventional example, in order to seal the resistance film 3 ', the four sides of the overcoat 5' are projected beyond the four edges of the resistance film 3 ', and the protrusion margin is usually 300 to 1000 μm. Therefore, the distance from the overcoat end 31e ′ to the fuse element connection portion of the intermediate electrode 20 ′ is L2−300 μm at the maximum.
  Therefore, according to the third aspect, the effective wetting distance from one end of the overcoat to the fuse element is longer than that of the conventional example, and in order to increase the effective wetting area by increasing the effective wetting distance, the fuse element connection of the intermediate electrode 20 Even if the effective wetted area of the intermediate electrode 20 is reduced by reducing the width of the part, the effective wetted area can be reduced only slightly, and this is synergistic with the fact that the volume of the fuse element is reduced. The effect of splitting operation can be sufficiently guaranteed.
[0023]
the aboveIn this case, even if the distance L1 from the overcoat end 51e to the fuse element 4 is smaller than the distance (reference distance) L2 from the fuse element 4 to the resistance film end 31e (L1 <L2), L1> L2 As long as the condition of −300 μm is satisfied, it can contribute to the enhancement of the spheroidizing performance of the fuse element 4 as described above.
[Expression 1]
  L1 ≧ L2
Then, since the effective distance L1 for the molten alloy in the intermediate electrode spreading toward the film resistance side can be increased by that much, it is desirable that L1 ≧ L2.
[0024]
Shown in (a) and (b) of FIG.YouIn the embodiment, the sealing performance of the resistance film one end portion 31 depends on the overlapping interface between the intermediate electrode one end portion 201 and the overcoat one end portion 51, and the arrangement and dimensions of the intermediate electrode and the resistance film are fixed. The interface distance L3 is given by the protrusion margin of the overcoat end 51e with respect to the intermediate electrode piece end 201e. However, if the overlapping interface distance L3 is made too long, the effective distance L1 for the molten alloy in the intermediate electrode 20 wetting and spreading toward the film resistance side. And the effect of improving the spheroidizing performance is reduced, so that the overlap interface distance L3 is normally set to 600 μm or less.
[0025]
  AboveThe production of the protective element includes (a) a step of abutting the mesh screen of the membrane resistance pattern to print the membrane resistance and then baking, (b) a step of abutting the mesh screen of the electrode pattern to print and then baking the electrode, (C) A process of printing the overcoat by contacting the mesh screen for overcoat and baking the next, (d) A resistance value of the film resistance is set to a predetermined value by trimming as needed before or after the overcoat printing / baking process. (E) connecting a soluble alloy piece between the first and second electrodes and then applying a flux; (f) connecting a lead conductor to the first to third electrodes by spot welding; g) Proceeding in the order of the process of sealing with the case cover, which takes time to connect the lead conductors, and which may affect the fusible alloy pieces, for example, solder When using only the step of connecting the lead conductor to the first to third electrodes, it is safe to the front of the first to the second electrode connecting the fusible alloy piece is then applying a flux.
[0026]
  After the operation of the protective element described above, the electrodes electrically connected by the fusible alloy pieces before the operation are electrically disconnected, and the circuit voltage acts between the electrodes, resulting in a short distance between the electrodes. In some places, re-conduction due to a flashover may occur. In order to prevent this re-conduction, as shown in FIG. 3, at least a portion where the intermediate electrode 20 or the third electrode 23 connected to the membrane resistance and another electrode (the first electrode or the second electrode) face each other

An extension portion

511, 512 or 513 of the overcoat 5 can be formed along a part of the edge portion of the electrode, and insulation reinforcement can be performed so as to prevent the flashing.
[0027]
  (A) in FIG.Different from the protection element according to the present invention.Drawing which shows an Example, (b) of FIG. 4 is a roll sectional view in (a) of FIG.
  4A and 4B, reference numeral 1 denotes a heat-resistant insulating substrate such as a ceramic substrate. Reference numeral 3 denotes a film resistance provided on the insulating substrate, which is provided by printing and baking of a resistance paste as described above. Reference numeral 5 denotes an overcoat for the film resistor 3. One end 31 of the resistive film 3 protrudes from the overcoat end 51e by a predetermined distance a, and the other end 32 of the resistive film 3 extends from the overcoat end 52e to a predetermined distance b. Only protruding.
  In FIG. 4A, 20 is an intermediate electrode, 21 is a first electrode, 22 is a second electrode, and 23 is a third electrode. The width W of the fuse element connecting portion of the intermediate electrode 20 is set to the first electrode 21, The widths W1 and W2 of the fuse element connecting portions of the second electrodes 22 are made narrower, and W <W1 and W2 (normally W1 = W2). Further, the distance d1 between the first electrode 21 and the intermediate electrode 20, the distance d2 between the second electrode 22 and the intermediate electrode 20, the distance d between the lead conductor mounting portion 230 of the third electrode 23 and the second electrode 22, Even if the circuit between them is electrically cut off by the division of the element 4 and the circuit voltage acts between the cuts, the intervals are set to a predetermined distance or more so that the insulation at each interval can be guaranteed. Usually, d1 = d2 <d.
  4 (a) and 4 (b), the third electrode 23 is electrically connected to the membrane resistor 3 in contact with the protrusion margin b. One end (membrane resistance side end) 201 of the intermediate electrode 20 is positioned so as to exceed one end 51 e of the overcoat 5, and the intermediate electrode 20 contacts the film resistor 3 at the protrusion a of the resistance film one end 31. Are electrically connected.
  Reference numeral 4 denotes a fuse element, which is connected between the first electrode 21 and the second electrode 22 by welding or the like as in the embodiment shown in FIG. 1, and the intermediate portion is connected to the intermediate electrode 20 by welding or the like. Reference numeral 6 denotes a flux applied to the fuse element 4.
  Although the lead conductor and the insulation coating do not appear in the figure, they have substantially the same configuration as in the first embodiment.
[0028]
  FIG. 4C shows a conventional example with a cross section at the same position as the cross section of FIG.
  4B and 4C, the

positions

31e and 31e 'at one end of the film resistor are the same, and the distance L2 from the

fuse elements

4 and 4' to this position has the same dimension. Further, the contact margin a between the one end portion 31 (31 ') of the membrane resistor and the one end portion 201 (201') of the intermediate electrode is made the same, and the contact electric resistance therebetween is made equal.
  In the conventional example, as described above, the overcoat end 51e ′ protrudes from the film resistance end 31e ′ by at least 300 μm. Therefore, the effective distance with respect to the wetting and spreading of the melted soluble alloy toward the film resistance is at most L2−. 300 μm. On the other hand, in the thermal fuse with a resistor according to claim 4, one end portion 201 of the intermediate electrode 20 is positioned beyond the overcoat end 51e, and the wet and spread of the melted soluble alloy toward the film resistance side Can be made larger than the effective distance L2-300 μm of the conventional thermal fuse with a resistor.
  Therefore, even if the effective wetting area of the intermediate electrode is reduced by reducing the width of the fuse element connecting portion of the intermediate electrode, according to claim 4, the effective wetting due to the increase of the effective wetting distance from one end of the overcoat to the fuse element. By increasing the area, the reduction of the effective wet area can be kept light, and the cutting operation performance can be sufficiently ensured by the synergistic effect of this and the fact that the volume of the fuse element is reduced.
[0029]
  As shown in FIG.The protection element is manufactured by (a) a step of abutting a mesh screen of a membrane resistance pattern to print a membrane resistance and then baking, (b) a step of abutting a mesh screen for overcoat to print an overcoat and then baking (C) a step of printing the electrode by contacting the mesh screen of the electrode pattern and then baking it; (d) a step of setting the resistance value of the film resistance to a predetermined value by trimming, if necessary; (e) a first step The process sequence of connecting the fuse element to the second electrode and then applying flux, (f) connecting the lead conductor to the first to third electrodes by spot welding, and (g) sealing with the case cover When using lead wires that require time to connect the lead conductors and that may affect the fuse element thermally, such as soldering, In the step of connecting the lead conductor, it is safe to the previous step of connecting the fuse element to electrodes then applying flux.
[0030]
  During ~As another means for increasing the effective wetting area of the intermediate electrode despite the narrowing of the fuse element connection part of the intermediate electrode, a part different from the fuse element connection part of the intermediate electrode is shown in FIG. ) And (b), as shown in (b), the insulation distance between the intermediate electrode 20 and the first electrode 21 and the insulation distance between the intermediate electrode 20 and the second electrode 22 even under this bulge. The first electrode 21 and the second electrode 22 are recessed according to the bulging so as to maintain a predetermined insulation distance [FIG. 5 (A)] or retracted 211, 221 [FIG. B)].
[0031]
In any of the above-described embodiments, if the cross-sectional area of the lead conductor 73 of the third electrode 23 is reduced, the heat conduction outflow of the heat generated by the conduction of the film resistor 3 through the lead conductor 73 is suppressed, and the membrane resistance 3 Since the heat generation speed can be increased and the operation speed of the protective element can be further increased, the cross-sectional area of the lead conductor connected to the third electrode can be changed to other lead conductors (lead conductors connected to the first electrode and the second electrode). In contrast, it is preferably about 0.8 to 0.5 times.
  In this case, if the cross-sections of all the lead conductors are made square with the same height and the cross-sectional area is reduced by narrowing the width, the heights of all the lead conductors can be made equal, and an insulating plate or insulating case for the cover can be mounted. When placed, it can be horizontal without tilting, and all lead conductors can be easily manufactured from a punched lead frame.
[0032]
  According to the thermal fuse with a resistor according to the present invention, a precursor to an abnormality of the device is detected, and the membrane resistance is energized and heated with this detection, and the fuse element is blown by the generated heat to cut off the energization of the device. This energization interruption also interrupts the energization to the membrane resistance. For example, when a lithium ion secondary battery is charged, a voltage rise that occurs during overcharge is detected, and the membrane resistance is energized and heated with this detection, and the fuse element is blown by the generated heat, and the secondary battery is removed from the charger. Can be blocked.
[0033]
  FIG. 6 shows a secondary battery protection circuit using the resistor-equipped thermal fuse of the above embodiment.
  In FIG. 6, S is a charger and A is a lithium ion secondary battery. B denotes a detection operation circuit unit, in which a Zener diode D is connected to the base of the transistor Tr via a resistor R, an emitter is grounded, and a positive side of the Zener diode D is connected to a high voltage side of the circuit. C represents the protective element of the above embodiment, in which the first electrode 21 and the second electrode 22 are connected between the charger S and the secondary battery A, and the third electrode 23 is connected to the collector of the transistor Tr. .
  The breakdown voltage of the Zener diode D is set low with respect to the voltage rise that occurs when the secondary battery is overcharged. When the voltage rises due to overcharge, a base current flows through the transistor Tr and a large collector current flows, causing the film to flow. The resistor 3 generates heat, and the generated heat is transmitted to the fuse element 4 through the intermediate electrode 20, and the fuse element 4 is melted. The first electrode 21 and the second electrode 22 are wetted and spread, and are divided between the intermediate electrode 20 and the first electrode 21 and between the intermediate electrode 20 and the second electrode 22, and the membrane resistance 3 is cut off from the battery.
  In the protection element according to the present invention, the melting point of the fuse element is selected as the protection temperature of the device, for example, the secondary battery (desired temperature at 80 ° C. to 120 ° C.), and the protection element substantially follows the device temperature. If the device is installed in thermal contact with the device so that the temperature can be raised, the power supply to the device can be cut off at the protection temperature, and abnormal heat generation of the device beyond the protection temperature, and thus a fire can be prevented.
[0034]
  According to the present inventionProtective elementThe above-mentioned film resistance is omitted, the melting point of the fuse element is set to the device's protection temperature, the device is attached to the device under thermal contact, the device is turned off at the protection temperature, and the device overheats the protection temperature. As a result, in a form to prevent the occurrence of fireuse7 and 8 can beUse formShow.
  In FIG. 7, reference numeral 1 denotes a heat-resistant insulating substrate such as a ceramic substrate.

Reference numerals

21 and 22 denote a first electrode and a second electrode provided by printing and baking a conductive paste, and are provided with lead

conductor attachment portions

210 and 220. Reference numeral 20 denotes an intermediate electrode, which is disposed in the middle between the first electrode 21 and the second electrode 22 and includes a lead conductor mounting portion 200 at a position deviated from the middle. Reference numeral 4 denotes a fuse element made of a fusible alloy, which is connected between the first electrode 21 and the second electrode 22 by welding or the like, and the middle is connected to the intermediate electrode 20 by welding or the like. The width W of the fuse element connecting portion of the intermediate electrode 20 is made narrower than the width W1, W2 of the fuse element connecting portion of each of the first electrode 21 and the second electrode 22, and W <W1, W2. Usually, W1 = W2.
The distance d1 between the first electrode 21 and the intermediate electrode 20 and the distance d2 between the second electrode 22 and the intermediate electrode 20 are electrically disconnected from each other by the division of the fuse element 4, and the circuit voltage is between the interruptions. Even if the above acts, each interval is set to be equal to or greater than a predetermined distance so that insulation at each interval can be guaranteed, and d1 = d2 is normally set.
Reference numeral 6 denotes a flux applied to the fuse element 4.

Reference numerals

70, 71 and 72 denote lead conductors connected to the respective lead conductor attachment portions 200 to 220 of the intermediate electrode 20 to the second electrode 22 by welding or the like, and it is preferable to use spot resistance welding for welding.
  Reference numeral 8 denotes an insulating covering, for example, a structure in which a sealant such as an epoxy resin is applied, or a structure in which a protective plate is fixed on a sealant layer, or a cover is placed on a substrate and a frame around the cover The lead conductor can be drawn out from the lead conductor lead-out hole and sealed with an adhesive such as an epoxy resin.
[0035]
  (B) and (b) in FIG. 8 are different from the above.Usage formIn contrast to the embodiment shown in FIG. 7, a portion different from the fuse element connecting portion of the intermediate electrode is bulged, and the insulation between the intermediate electrode 20 and the first electrode 21 even under this bulge is shown. The first electrode 21 and the second electrode 22 are locally recessed in response to the bulge so that the distance and the insulation distance between the intermediate electrode 20 and the second electrode 22 are maintained at a predetermined insulation distance [FIG. (A)] or retracted ((B) in FIG. 8).
[0036]
  In any of the above embodiments, the lead conductor is provided. However, in the thermal fuse with a resistor, the first electrode, the second electrode, and the third electrode are turned to the chip type by passing through the substrate side surface to the back side of the substrate. In the fuse, the first electrode, the second electrode, and the intermediate electrode can be turned to the chip type by turning the substrate to the back surface side through the substrate side surface.
[0037]
  In the present invention, the overcoat material is an insulator and is not limited to a glass coat, and a synthetic resin coat such as an epoxy resin coat can also be used.
  In the present invention, the electrode material is not only a fired type comprising a mixture of conductive particles, glass frit and an organic solvent, but also a thermosetting type comprising a mixture of conductive particles, a thermosetting resin (for example, epoxy resin) and a solvent. As the conductive particles, metal particles such as silver, palladium, gold, and copper, carbon, and the like can be used.
  In the present invention, the film resistance material is not only a baking type composed of a mixture of resistance particles, glass frit and an organic solvent, but also a thermosetting type composed of a mixture of resistance particles, a thermosetting resin (for example, epoxy resin) and a solvent. It is also possible to use metal oxide particles such as ruthenium oxide particles as resistance particles. In addition, it is possible to use a Ti—Si resistance paste.
  For flux, natural rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) and organic acids such as diethylamine hydrochloride, diethylamine hydrobromide, adipine etc. are added to these purified rosins. Can be used.
  In the present invention, the insulating substrate can be used without particular limitation as long as it is insulative and has heat resistance capable of withstanding the formation of electrodes and film resistance, such as a ceramic plate such as an alumina ceramic plate, a heat resistant plastic plate, A glass fiber reinforced plastic plate, a metal plate having an insulating film on the surface, or the like can be used.
[0038]
  The vertical x horizontal dimension of the insulating substrate in the protective element according to the present invention is normally (4.0 to 10.0) mm x (4.0 to 10.0) mm. The arrangement pattern and dimensions of the electrodes and film resistors are set according to the rated current and the rated voltage.
  When the rating is 10 A × 50 V, the width of the lead conductor connecting portion of the intermediate electrode is 300 to 400 μm, and the distance between the first electrode and the intermediate electrode and the distance between the second electrode and the intermediate electrode are 300 to 1000 μm.
[0039]
  In the present invention, it is preferable to use an alloy that does not contain an element harmful to a biological system, for example, a Sn—In—Bi alloy for the fuse element. Table 1 shows the liquidus temperature and specific resistance values of Sn 43 to 70%, In 0.5 to 10%, and the remaining Bi as an example of the Sn-In-Bi alloy composition.
  However, the liquidus temperature is DSC [reference sample (unchangeable) and measurement sample are placed in a nitrogen gas container, power is supplied to the container heater to heat both samples at a constant rate, and the thermal change of the measurement sample. The change in the amount of heat energy input due to is detected by a differential thermocouple].
[Table 1]

  Although the specific resistance value is as high as 20 μΩcm or more, according to the present invention, the fuse element length can be shortened so that the resistance value of the fuse element can be kept at a normal value, and good operating performance can be guaranteed.
[0040]
  In order to reduce the specific resistance value of the alloy and refine the crystal structure and reduce the heterogeneous interface in the alloy to improve the work strain and stress dispersibility, Ag, Au, 0.01 to 7 parts by weight of at least one of Cu, Ga, Ge, Ni, Pd, Pt, Sb, and P can be added. The reason why the added amount is 0.01 to 7 parts by weight is that the effect is very insufficient if the amount is less than 0.01 part by weight, and if the amount exceeds 7 parts by weight, the melting characteristics of the alloy change greatly. This is because problems such as it becomes difficult to keep the variation in the allowable range.
[0041]
【Example】
  Regarding the operating temperature, the number of samples in each of the example and the comparative example was 50 pieces, and immersed in an oil bath at a heating rate of 1 ° C./min while energizing a current of 0.1 ampere. The oil temperature was taken as the operating temperature.
[0042]
[Comparative Example 1]
This is a conventional product shown in FIG. 9, and an insulating substrate 1 is made of an alumina ceramic plate having a length × width × thickness of 6 mm × 6 mm × 0.64 mm, and film resistance 3 is formed by printing and baking a ruthenium oxide-based resistance paste. The electrodes 20 to 23 were formed by printing and baking a silver-based conductive paste. The vertical and horizontal dimensions of the first electrode 21 and the second electrode 22 (both excluding the lead conductor mounting portion) are 1.7 mm × 600 μm, and the vertical and horizontal dimensions of the intermediate electrode 20 are 1.7 mm × The distance between the first electrode and the intermediate electrode and the distance between the second electrode and the intermediate electrode were set to 500 μm. An overcoat was formed by printing and baking glass paste. For the fuse element, an alloy having Sn 46.5% -Pb 29.8% -Cd 16.7% -In 7% and a specific resistance value of 15 μΩcm was used, the fuse element outer diameter was 500 μmφ, and the length was 3.3 mm. The resistance value of the fuse element is 25 mΩ. An Sn-plated copper lead conductor having a thickness x width of 300 μm × 1000 μm is attached to each lead conductor attachment portion of the first electrode and the second electrode, and an attachment portion thickness × width is 300 μm to the lead conductor attachment portion of the intermediate electrode 20 of the third electrode. × 1000μm, narrow width thickness × 300μm × 700μm Sn-plated copper lead conductors are connected, and a vertical x horizontal x thickness of 4mm x 4mm x 0.64mm alumina ceramic plate is placed on top of these The space between the cover plate and the substrate was sealed with an epoxy resin. For flux 6, a composition comprising 80 parts by weight of rosin, 20 parts by weight of stearic acid, and 1 part by weight of diethylamine hydrobromide was used.
  The operating temperature was measured and found to be 135 ± 2 ° C.
[0043]
〔Example〕
  Compared to Comparative Example 1, the width of the intermediate electrode is 300 μm, the alloy of Bi52% -Sn46% -In2% and specific resistance value 34 μΩcm is used for the fuse element, the length of the fuse element is 2.4 mm, and the fuse element The fuse element was the same as Comparative Example 1 except that the outer diameter of the fuse element was increased to 640 μmφ in order to make the resistance value substantially the same as that of Comparative Example 1.
  The operating temperature was measured and found to be 136 ± 2 ° C.
[0044]
[Comparative Example 2]
  As in Example 1, an alloy having Bi52% -Sn46% -In2% and a specific resistance of 34 μΩcm was used for the fuse element. The outer diameter of the fuse element is set to 1.5 of Comparative Example 1 so that the electrode element size, arrangement, and fuse element length remain the same as in Comparative Example 1 and the resistance value of the fuse element is substantially the same value as in Comparative Example 1 and Examples. Double (√34 / √15 times) 750 μmφ.
  When the operating temperature was measured, it was considerably higher than that of Comparative Example 1 and the variation was 141 ± 5 ° C.
  As is clear from the comparison between the example and the comparative example 1, according to the present invention, the equivalent operation performance can be maintained even though the width of the intermediate electrode is reduced from 1200 μm to 300 μm, and the protective element is downsized. Can be achieved.
  In Comparative Example 2, it is estimated that due to the influence of the area of the intermediate electrode on the fuse element volume, the operation performance was reduced as a result of taking a long time until melting after melting the fusible alloy. Despite the narrowing, good operating performance was exhibited.
[0045]
【The invention's effect】
  According to the present inventionAccording to the protective element, the fuse element can be shortened to keep the fuse element below a predetermined resistance value, and the size of the protective element can be reduced as the fuse element is shortened. In addition, when the specific resistance value of the fuse element is increased, the resistance value of the fuse element can be maintained at a predetermined value by shortening the length of the fuse element as the specific resistance value increases. The volume of the fuse element can be reduced compared to the case where the resistance value of the fuse element is maintained at a predetermined value by increasing the outer diameter of the fuse element while keeping the length of the fuse element unchanged. Since it becomes more noticeable as the value increases, the operation performance can be improved by decreasing the fuse element volume as the specific resistance value of the fuse element increases.
[0046]
  According to the present inventionAccording to the protective element, the above-described effect can be obtained in the thermal fuse with a resistor.
[0047]
  According to the present inventionAccording to the protective element, a film resistor, a fuse element, and an intermediate electrode are provided on one side of the substrate, one end of the film resistor is connected to one end of the intermediate electrode, and an intermediate distance is separated from the one end of the film resistor by a predetermined distance. In a thermal fuse with a resistor, in which a fuse element is bonded to the electrode part and overcoated on the film resistance, the process of printing and baking the electrode including the intermediate electrode and the film resistance are compared to the conventional temperature fuse with a resistor. By simply switching the printing and baking processes and adjusting the overcoat printing dimensions so as to widen the space between the overcoat end and the fuse element, the effective wet distance for the molten alloy at the intermediate electrode can be increased. It is possible to provide a temperature fuse with a resistor that can guarantee good operation performance even when the intermediate electrode is narrowed.
[0048]
  According to the present inventionAccording to the protective element, a film resistor, a fuse element, and an intermediate electrode are provided on one surface of the substrate, and one end of the film resistor is connected to one end of the intermediate electrode, and the intermediate is separated from the one end of the film resistor by a predetermined distance. A fuse element is joined to the electrode part, an overcoat is applied on the membrane resistor, one end of the membrane resistor protrudes from one end of the overcoat, and one end of the intermediate electrode covers the projected one end of the membrane resistor and one end of the overcoat Therefore, by increasing the dimension that covers one end of the overcoat on one end of the intermediate electrode, the effective wet distance to the molten alloy at the intermediate electrode can be increased, and good operation performance can be achieved even when the width of the intermediate electrode is reduced. We can provide temperature fuses with resistors that can be guaranteed.
[0049]
  According to the present inventionAccording to the protective element, since the wetting area of the intermediate electrode can be increased while keeping the fuse element short, the temperature with a resistor that can guarantee good operating performance even under the narrowing of the intermediate electrode Can provide fuses.
[0050]
  According to the present inventionAccording to the protection element, it is possible to insulate and reinforce the voltage acting between the electrodes when the fuse element is divided, to prevent re-conduction after the division, and to ensure stable interruption.
[0051]
  According to the present inventionAccording to the protective element, the rate of temperature rise of the film resistance can be increased, and the operating speed of the temperature fuse with a resistor can be increased.
[Brief description of the drawings]
[Figure 1]According to the present inventionIt is drawing which shows one Example of a protection element.
[Figure 2]It is drawing which shows a part of said Example.
[Fig. 3]It is drawing which shows another part of the said Example.
[Fig. 4]It is drawing which shows a part of another Example of the protection element which concerns on this invention..
[Figure 5]It is drawing which shows the Example different from the above of the protection element which concerns on this invention..
FIG. 6 is a circuit diagram showing how to use the protection element according to the present invention.
FIG. 7 shows a protection element according to the present invention.Example of usageFIG.
FIG. 8 shows a protection element according to the present invention.Example of another use formFIG.
FIG. 9 is a view showing a conventional protection element.
FIG. 10 is a drawing showing another conventional protection element.
[Explanation of symbols]
  1 Insulating substrate
  20 Intermediate electrode
  21 First electrode
  22 Second electrode
  23 Third electrode
  3 Membrane resistance
  31 One end of membrane resistance
  31e One end of membrane resistance
  4 Fuse element
  5 Overcoat
  51 One end of overcoat
  51e One end of overcoat
  6 Flux
  8 Insulation cover

Claims

A first electrode, a second electrode, and a third electrode are provided, an intermediate electrode is provided between the first electrode and the second electrode, and each end of the fuse element made of a fusible alloy is connected to the first electrode and the second electrode. The fuse element is connected to the intermediate electrode, the film resistance is connected between the intermediate electrode and the third electrode, and the first electrode and the second electrode of the molten alloy of the fuse element melted in operation. The fuse element is divided by wetting and spreading to each of the intermediate electrode and the intermediate electrode, and in order to ensure insulation between the first electrode and the second electrode and the intermediate electrode after the separation, a predetermined insulation distance is provided between them. spaced, the protective element width of the fuse element connection portion of the intermediate electrode is narrower than the width of the first electrode, respectively second electrode fuse element connection portion, the fuse element and the membrane resistance insulating substrate piece An overcoat for the membrane resistance is provided, the membrane resistance side one end of the intermediate electrode covers one end of the membrane resistance, the intermediate electrode side one end of the overcoat covers the intermediate electrode one end, A protective element characterized in that a distance L 1 from a fuse element connecting portion to one end of the overcoat satisfies L 1 > L 2 −300 μm with respect to a distance L 2 from the same portion to one end of the membrane resistor .

A first electrode, a second electrode, and a third electrode are provided, an intermediate electrode is provided between the first electrode and the second electrode, and each end of the fuse element made of a fusible alloy is connected to the first electrode and the second electrode. The fuse element is connected to the intermediate electrode, the film resistance is connected between the intermediate electrode and the third electrode, and the first electrode and the second electrode of the molten alloy of the fuse element melted in operation. The fuse element is divided by wetting and spreading to each of the intermediate electrode and the intermediate electrode, and in order to ensure insulation between the first electrode and the second electrode and the intermediate electrode after the separation, a predetermined insulation distance is provided between them. spaced, the protective element width of the fuse element connection portion of the intermediate electrode is narrower than the width of the first electrode, respectively second electrode fuse element connection portion, the fuse element and the membrane resistance insulating substrate piece An overcoat is provided on the membrane resistor, one end of the membrane resistor protrudes from one end of the overcoat, and one end of the intermediate electrode covers the projected one end of the membrane resistor and one end of the overcoat. Protective element .

The protective element according to claim 1, wherein a specific resistance value of the fuse element is 20 μΩcm or more.

The soluble alloy is any of an In—Sn—Bi alloy, a Bi—Sn—Sb alloy, an In—Sn alloy, an In—Bi alloy, a Bi—Sn alloy, and an In alloy. The protective element according to claim 1.

The composition of the In—Sn—Bi alloy is (1) 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, remaining Bi, (2) 25% ≦ Sn ≦ 40%, 50% ≦ In ≦ 55%, remaining Bi, (3) 25% <Sn ≦ 44%, 55% <In ≦ 74%, 1% ≦ Bi <20%, (4) 46% <Sn ≦ 70%, 18% ≦ In <48 %, 1% ≦ Bi ≦ 12%, (5) 5% ≦ Sn ≦ 28%, 15% ≦ In <37%, remaining Bi (Bi57.5%, In25.2%, Sn17.3% and Bi54) %, In29.7%, and Sn16.3%, except for the range of Bi ± 2%, In and Sn ± 1%), (6) 10% ≦ Sn ≦ 18%, 37% ≦ In ≦ 43 %, Remaining Bi, (7) 25% <Sn ≦ 60%, 20% ≦ In <50%, 12% <Bi ≦ 33%, (8) any one of (1) to (7) 100 Add one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P to 0.01 parts by weight in total, (9) 33% ≦ Sn ≦ 43% 0.5% ≦ In ≦ 10%, remaining Bi, (10) 3-5 parts by weight of Bi is added to 100 parts by weight of 47% ≦ Sn ≦ 49% and 51% ≦ In ≦ 53%, (11) 40% ≦ Sn ≦ 46%, 7% ≦ Bi ≦ 12%, remaining In, (12) 0.3% ≦ Sn ≦ 1.5%, 51% ≦ In ≦ 54%, remaining Bi, (13) 2. 5% ≦ Sn ≦ 10%, 25% ≦ Bi ≦ 35%, remaining In, (14) Ag, Au, Cu, Ni, Pd, Pt, Sb, 100 parts by weight of any one of (14), (9) to (13) One or more of Ga, Ge, and P are added in a total of 0.01 to 7 parts by weight, (15) 10% ≦ Sn ≦ 25%, 48% ≦ In ≦ 60%, and remaining Bi is 10 Add one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P to 0.01 parts by weight in total, and the composition of the Bi-Sn-Sb alloy is (16) 30% ≦ Sn ≦ 70%, 0.3% ≦ Sb ≦ 20%, remaining Bi, (17) Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge in 100 parts by weight of (16) In addition, 0.01 to 7 parts by weight of one or more of P are added, and the composition of the In—Sn alloy is (18) 52% ≦ In ≦ 85%, the remaining Sn, (19) 100 of (18) One to two parts or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P are added in a total of 0.01 to 7 parts by weight, and the composition of the In-Bi alloy is (20 ) 45% ≦ Bi ≦ 55%, remaining In, (21) In 100 parts by weight of the composition of (20), Ag, Au, Cu, Ni, P , Pt, Sb, Ga, Ge, P or one or more of 0.01 to 7 parts by weight in total, the composition of the Bi-Sn alloy is (22) 50% <Bi ≦ 56%, the remaining Sn, (23) Addition of 0.01 to 7 parts by weight of one or more of Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge, P to 100 parts by weight of (22). A total of 0.01 to 7 parts by weight of one or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P is added to 100 parts by weight of (24) In. (25) 90 Total of one or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, P in 100 parts by weight of% ≦ In ≦ 99.9%, 0.1% ≦ Ag ≦ 10% 0.01-7 parts by weight, (26) 95% ≦ In ≦ 99.9%, 0.1% ≦ Sb ≦ 5% The protective element according to claim 4, wherein one or more of Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P are added in a total of 0.01 to 7 parts by weight. .

The protective element according to any one of claims 1 to 5, wherein the width of the fuse element connecting portion of the intermediate electrode is 300 to 400 µm, and the predetermined insulation distance is 300 to 1000 µm.

The width of the intermediate electrode bulges at a part different from the fuse element connecting portion, and the widths of the first electrode and the second electrode are locally retreated or recessed according to the bulge. The protective element in any one of 1-6.

A fuse element and a membrane resistor are provided on one side of an insulating substrate, an overcoat for the membrane resistor is provided, and at least a part of an electrode edge of a portion where at least one electrode connected to the membrane resistor and another electrode face each other The overcoat is extended along the part, The protection element in any one of Claims 1-7 characterized by the above-mentioned.

The cross-sectional area of the lead conductor connected to the third electrode is 0.8 to 0.5 times the cross-sectional area of the lead conductor connected to each of the first electrode and the second electrode. Item 9. The protective element according to any one of Items 1 to 8.