JP2004146228A

JP2004146228A - Lead free alloy thermal fuse

Info

Publication number: JP2004146228A
Application number: JP2002310685A
Authority: JP
Inventors: Kiyotomo Terasawa; 寺澤　精朋; Kiyohito Ishida; 石田　清仁
Original assignee: NEC Schott Components Corp
Current assignee: NEC Schott Components Corp
Priority date: 2002-10-25
Filing date: 2002-10-25
Publication date: 2004-05-20
Anticipated expiration: 2022-10-25
Also published as: JP4338377B2

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a lead free alloy thermal fuse superior in operating reliability in a range of 70-109 °C without containing lead or cadmium which causes environmental problems. <P>SOLUTION: In the thermal fuse which uses a fusible alloy as a fuse element, a lead free alloy thermal fuse is obtained by using a low melting-point fusible alloy in which a ternary alloy composed of the composition of Bi 64 wt% to 69 wt%, Ag 0.05 wt% to 0.3 wt%, and In the rest, the composition of Bi 47 wt% to 55 wt%, Ag 0.05 wt% to 0.2 wt%, and In the rest, and the composition of Bi 32 wt% to 37 wt%, Ag 0.01 wt% to 0.1 wt%, and In the rest is used. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、保護素子に関するもので、詳しくは、電気・電子機器等に使用され、特定温度で溶融する可溶合金を用いた温度ヒューズに関する。
【０００２】
【従来の技術】
電気・電子機器等を過熱損傷から保護する保護素子として、特定温度で動作して回路を遮断する温度ヒューズが用いられている。可溶合金型温度ヒューズは、感温素子として特定温度で溶融する可溶合金を用いて、この可溶合金に通電し、周囲温度の上昇により可溶合金が溶融して回路を遮断するものである。
【０００３】
さらに、可溶合金と抵抗体とを具備し、抵抗体の通電過熱により可溶合金を強制的に溶断させる抵抗内蔵型温度ヒューズと称される保護素子もある。
【０００４】
【発明が解決しようとする課題】
上記の可溶合金型温度ヒューズは、保温コタツ、炊飯器等の家電製品、液晶テレビや複写機器等のＯＡ機器、照明機器などに保護素子として用いられている。このうち９８〜８８℃の範囲の動作温度を有する可溶合金には、従来５２Ｂｉ−３２Ｐｂ−１６Ｓｎ（重量％）三元合金（９８℃）、４２．５Ｉｎ−３８．６Ｓｎ−１２．４Ｃｄ−６．５Ａｇ（重量％）四元合金（９４℃）、４４Ｉｎ−４２Ｓｎ−１４Ｃｄ（重量％）三元合金（９３℃）、５０．５Ｂｉ−３１Ｐｂ−１５．５Ｓｎ−３Ｉｎ（重量％）四元合金（９０℃）、４８Ｂｉ−３０Ｐｂ−１５Ｓｎ−７Ｉｎ（重量％）四元合金（８４℃）、４２〜５０Ｉｎ−１０〜１５Ｃｄ−０．８〜５Ｚｎ−残Ｓｎ（重量％）四元合金（８５℃）など人体に有害な重金属である鉛やカドミウムを１０重量％以上含有するものがあった。最近、廃棄された電気・電子機器から雨水などの作用により有害金属が溶出し、地下水に深刻な汚染をもたらしていることが、地球環境上の問題となり、可溶合金の改良が必要とされている。
【０００５】
また、可溶合金型温度ヒューズの可溶合金は、特定の温度で液状化を進行させ球状化に導き溶断させる必要上、できれば単一の溶融点を持つ共晶合金組成が好ましい。さらに、電源回路に直列に実装される温度ヒューズの特性上から、かかる温度ヒューズの内部抵抗値は長期の高温保管によっても変化せず比抵抗が０．７９ｍΩ・ｍｍ以下であることが、省エネルギーの面や動作温度の安定性に上からも望ましい。
【０００６】
ＰｂやＣｄを含まず、溶融温度が１１０℃以下の合金を設計する場合、Ｂｉ−Ｉｎ二元合金系が良く知られているが、（例えば６７．４Ｂｉ−３２．６Ｉｎ（重量％）の１０９．７℃組成、５０Ｂｉ−５０Ｉｎ（重量％）の８８．７℃組成、３３．３Ｂｉ−６６．７Ｉｎ（重量％）の７２．７℃組成）これらの既存組成は何れも、ＢｉＩｎ、Ｂｉ_５Ｉｎ_３、ＢｉＩｎ_２の金属間化合物との共晶組成であるため機械強度が弱く、また温度ヒューズに組み込んだ場合の比抵抗が０．７９ｍΩ・ｍｍ以上あるため、温度ヒューズに実用できる可溶合金としてはそのまま利用し難い欠点がある。
【０００７】
本発明は、ＰｂやＣｄによる問題を生じないように、上記した可溶合金にＰｂおよびＣｄを使用しない環境対応型の鉛フリー合金型温度ヒューズを提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明による鉛フリー合金型温度ヒューズにおける可溶合金組成は、Ｂｉ−Ｉｎ二元合金系に、適量のＡｇを加えて結晶組織の微細化を図って機械的強度を改善すると共に、温度ヒューズの比抵抗を０．７９ｍΩ・ｍｍ以下に抑えたＢｉ−Ｉｎ−Ａｇ三元合金である。Ａｇの添加量については、Ａｇを過剰に添加することでＡｇＩｎ２が生成し固液共存域が増大し、またＡｇの添加量が少なすぎるとＡｇ添加の効果が得られないため、Ａｇ添加量をＢｉ−Ｉｎの構成組成に対して好適な範囲を定めたものである。
【０００９】
本発明の請求項１に係る鉛フリー合金型温度ヒューズは、感温素子にＢｉを６４重量％〜６９重量％、Ａｇを０．０５重量％〜０．３重量％、残部がＩｎからなる可溶合金を使用することで１０７〜１０９℃の動作温度を有する温度ヒューズを可能としたものである。
【００１０】
本発明の請求項２に係る鉛フリー合金型温度ヒューズは、感温素子にＢｉを４７重量％〜５５重量％、Ａｇを０．０５重量％〜０．２重量％、残部がＩｎからなる可溶合金を使用することで８７〜９７℃の動作温度を有する温度ヒューズを可能としたものである。
【００１１】
本発明の請求項３に係る鉛フリー合金型温度ヒューズは、感温素子にＢｉを３２重量％〜３７重量％、Ａｇを０．０１重量％〜０．１重量％、残部がＩｎからなる可溶合金を使用することで７０〜７３℃の動作温度を有する温度ヒューズを可能としたものである。
【００１２】
【発明の実施の形態】
本発明による実施の形態について図１を用いて説明する。図１は、本発明による鉛フリー合金型温度ヒューズを示し、アキシャル型温度ヒューズと称される温度ヒューズの縦断面図である。
【００１３】
図１に示すアキシャル型温度ヒューズは、Ｓｎ−Ｃｕめっき銅線からなる端子リード１、２間に、可溶合金３を抵抗溶接により接合した後、可溶合金３をロジン、ワックス、活性剤からなるフラックス４で被覆し、アルミナセラミック碍管５中に挿入して、エポキシ系封止樹脂６、７によりケース端部をそれぞれ封止して形成したものである。なお、端子リード１、２のＳｎ−Ｃｕめっき銅線は、必要に応じてＡｇめっき銅線、Ｓｎめっき銅線、Ｎｉめっき銅線等に変更でき、Ｓｎ−Ｃｕめっき銅線に限定されるものではない。
【００１４】
このような構成の温度ヒューズにおいて、可溶合金３にφ０．４〜０．７ｍｍ線のものを使用でき、また必要に応じて同一断面積を有するテープ状合金の平角片も使用できる。
【００１５】
本発明の温度ヒューズに用いられる可溶合金は、合金鋳塊の押出し加工により製造され、その後必要に応じてテープ状に圧延加工することもできる。
【００１６】
また、将来本発明の趣旨を逸脱しない範囲において、可溶合金３の線径は要求に応じてφ０．４ｍｍ以下とすることができ、さらにまた、要求に応じてφ０．７ｍｍ以上に変更することもできる。
【００１７】
また、本発明による鉛フリー合金型温度ヒューズは、アキシャル型温度ヒューズに限定されるものではなく、ラジアル型温度ヒューズ、薄型温度ヒューズ、抵抗内蔵型温度ヒューズと称される温度ヒューズに使用することができ、特定の形式に限定されるものではない。
【００１８】
【実施例】
本発明の実施例と比較例を表１に示す。表１はそれぞれの実施例と比較例における可溶合金組成とその固相温度、液相温度、固液共存域を示したもので、表中の固相、液相はそれぞれ合金の固相温度（℃）、液相温度（℃）を示し、液相温度と固相温度の差を固液共存域（℃）という。固液共存域が１０℃未満である時、その可溶合金を温度ヒューズの感温素子として使用できる。従って固液共存域が１０℃未満である実施例の可溶合金は、実施形態の温度ヒューズにおいて良好な動作特性を有する。以下実施例と比較例についての動作特性を説明する。
【表１】

【００１９】
（実施例１−４）請求項１の範囲にあるＢｉを６６．７０重量％、Ｉｎを３３．０７重量％、Ａｇを０．２３重量％とした組成のφ０．６ｍｍ線を押出し加工により作製し、この合金線を実施形態の温度ヒューズに適用した。実施例１−４の温度ヒューズ３０個に１０ｍＡの検知電流を通電しながら、１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ動作温度範囲は１０８±２℃であった。また、８８℃で５００時間、１０００時間、２０００時間それぞれ保管した実施例１−４の温度ヒューズ各１０個を電圧降下法により接触抵抗を除くように接続し、本体を含め２５ｍｍの点でリード間の電気抵抗を測定電流１００ｍＡで測定したところ、比抵抗０．６３±０．２ｍΩ・ｍｍの範囲を保持できることがわかった。さらに、この各１０個を１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ、高温保管後も動作温度１０８±２℃の初期範囲を維持できることがわかった。
【００２０】
（実施例２−２）請求項２の範囲にあるＢｉを５３．００重量％、Ｉｎを４６．８６重量％、Ａｇを０．１４重量％とした組成のφ０．６ｍｍ線を押出し加工により作製し、この合金線を実施形態の温度ヒューズに適用した。実施例２−２の温度ヒューズ３０個に１０ｍＡの検知電流を通電しながら、１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ動作温度範囲は９６±２℃であった。また、７６℃で５００時間、１０００時間、２０００時間それぞれ保管した実施例２−２の温度ヒューズ各１０個を電圧降下法により接触抵抗を除くように接続し、本体を含め２５ｍｍの点でリード間の電気抵抗を測定電流１００ｍＡで測定したところ、比抵抗０．５５±０．２ｍΩ・ｍｍの範囲を保持できることがわかった。さらに、この各１０個を１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ、高温保管後も動作温度９６±２℃の初期範囲を維持できることがわかった。
【００２１】
（実施例２−５）請求項２の範囲にあるＢｉを４９．７０重量％、Ｉｎを５０．２２重量％、Ａｇを０．０８重量％とした組成のφ０．６ｍｍ線を押出し加工により作製し、この合金線を実施形態の温度ヒューズに適用した。実施例２−５の温度ヒューズ３０個に１０ｍＡの検知電流を通電しながら、１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ動作温度範囲は８９±２℃であった。また、６９℃で５００時間、１０００時間、２０００時間それぞれ保管した実施例２−５の温度ヒューズ各１０個を電圧降下法により接触抵抗を除くように接続し、本体を含め２５ｍｍの点でリード間の電気抵抗を測定電流１００ｍＡで測定したところ、比抵抗０．５５±０．２ｍΩ・ｍｍの範囲を保持できることがわかった。さらに、この各１０個を１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ、高温保管後も動作温度８９±２℃の初期範囲を維持できることがわかった。
【００２２】
（実施例２−９）請求項２の範囲にあるＢｉを４８．５０重量％、Ｉｎを５１．４３重量％、Ａｇを０．０７重量％とした組成のφ０．６ｍｍ線を押出し加工により作製し、この合金線を実施形態の温度ヒューズに適用した。実施例２−９の温度ヒューズ３０個に１０ｍＡの検知電流を通電しながら、１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ動作温度範囲は８８±２℃であった。また、６８℃で５００時間、１０００時間、２０００時間それぞれ保管した実施例２−９の温度ヒューズ各１０個を電圧降下法により接触抵抗を除くように接続し、本体を含め２５ｍｍの点でリード間の電気抵抗を測定電流１００ｍＡで測定したところ、比抵抗０．４７±０．２ｍΩ・ｍｍの範囲を保持できることがわかった。さらに、この各１０個を１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ、高温保管後も動作温度８８±２℃の初期範囲を維持できることがわかった。
【００２３】
（実施例３−２）請求項３の範囲にあるＢｉ３４．２０重量％、Ｉｎを６５．７８重量％、Ａｇを０．０２重量％とした組成のφ０．６ｍｍ線を押出し加工により作製し、この合金線を実施形態の温度ヒューズに適用した。実施例３−２の温度ヒューズ３０個に１０ｍＡの検知電流を通電しながら、１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ動作温度範囲は７３±２℃であった。また、５３℃で５００時間、１０００時間、２０００時間それぞれ保管した実施例３−２の温度ヒューズ各１０個を電圧降下法により接触抵抗を除くように接続し、本体を含め２５ｍｍの点でリード間の電気抵抗を測定電流１００ｍＡで測定したところ、比抵抗０．３２±０．２ｍΩ・ｍｍの範囲を保持できることがわかった。さらに、この各１０個を１℃／分の割合で温度上昇する恒温槽（気相）中で動作させたところ、高温保管後も動作温度７３±２℃の初期範囲を保持できることがわかった。
【００２４】
【比較例】
（比較例１−１）ＢｉとＩｎの組成を請求項１の範囲にしＡｇの量を０．４重量％にした合金組成（６６．５３Ｂｉ−３３．０７Ｉｎ−０．４Ａｇ（重量％））は、固液共存域が２６．７℃と１０℃以上有し溶融開始から溶融完了までの温度域が広すぎるため温度ヒューズとして実用に至らなかった。同様にＡｇの量を０．５重量％にした合金組成（６６．４３Ｂｉ−３３．０７Ｉｎ−０．５Ａｇ（重量％））の固液共存域は３７．３℃もあり温度ヒューズとして実用できなかった。また、Ａｇの量を０．０５重量％以下とした合金組成（６６．９２Ｂｉ−３３．０７Ｉｎ−０．０１Ａｇ（重量％））のφ０．６ｍｍ線を押出し加工により作製を試みたが、合金強度が劣り脆すぎるため作製できなかった。請求項１におけるＢｉ、Ｉｎの組成範囲に対して有効なＡｇ配合量は０．０５〜０．３重量％であった。
【００２５】
（比較例２−１）ＢｉとＩｎの組成を請求項２の範囲にしＡｇの量を０．３重量％にした合金組成（５２．８４Ｂｉ−４６．８６Ｉｎ−０．３Ａｇ（重量％））は、固液共存域が、１０．１℃以上と１０℃以上有し溶融開始から溶融完了までの温度域が広すぎるため温度ヒューズとして実用に至らなかった。同様にＡｇの量を０．４重量％にした合金組成（５２．７４Ｂｉ−４６．８６Ｉｎ−０．４Ａｇ（重量％））の固液共存域は２３．１℃であり温度ヒューズとして実用できなかった。また、Ａｇの量を０．０５重量％以下とした組成（５３．１３Ｂｉ−４６．８６Ｉｎ−０．０１Ａｇ（重量％））のφ０．６ｍｍ線を押出し加工により作製を試みたが、合金強度が劣り脆すぎるため作製できなかった。請求項２におけるＢｉ、Ｉｎの組成範囲に対して有効なＡｇ配合量は０．０５〜０．２重量％であった。
【００２６】
（比較例３−１）ＢｉとＩｎの組成を請求項３の範囲にしＡｇの量を０．２重量％にした合金組成（３４．２Ｂｉ−６５．６Ｉｎ−０．２Ａｇ（重量％））は、固液共存域が２１．７℃と１０℃以上有し溶融開始から溶融完了までの温度域が広すぎるため温度ヒューズとして実用に至らなかった。同様にＡｇの量を０．３重量％にした合金組成（３４．２Ｂｉ−６５．５Ｉｎ−０．３Ａｇ（重量％））の固液共存域は３１℃であり温度ヒューズとして実用できなかった。また、Ａｇの量を０．０１重量％以下とした組成（３４．２００Ｂｉ−６５．７９５Ｉｎ−０．００５Ａｇ（重量％））のφ０．６ｍｍ線を押出し加工により作製を試みたが、合金が軟らかすぎるため組立時の変形が大きく温度ヒューズを作製できなかった。請求項３におけるＢｉ、Ｉｎの組成範囲に対して有効なＡｇ配合量は０．０１〜０．１重量％であった。
【００２７】
【発明の効果】
以上に説明したように本発明は、７０〜１０９℃で動作可能な信頼性に優れた鉛フリー合金型温度ヒューズをＰｂやＣｄを含有しないＢｉ−Ｉｎ−Ａｇ三元合金により実現するものである。
【図面の簡単な説明】
【図１】本発明の実施形態であるアキシャル型温度ヒューズの縦断面図
【符号の説明】
１、２　端子リード
３　　　可溶合金
４　　　フラックス
５　　　絶縁性のケース
６、７　封止樹脂[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a protection element, and more particularly, to a thermal fuse using a fusible alloy that is used at a specific temperature and is used for electric / electronic devices and the like.
[0002]
[Prior art]
2. Description of the Related Art A thermal fuse that operates at a specific temperature and shuts off a circuit is used as a protection element that protects electric and electronic devices from overheat damage. A fusible alloy-type thermal fuse uses a fusible alloy that melts at a specific temperature as a temperature-sensitive element, energizes this fusible alloy, and when the ambient temperature rises, the fusible alloy melts and interrupts the circuit. is there.
[0003]
Further, there is a protection element called a built-in resistor type thermal fuse that includes a fusible alloy and a resistor, and forcibly blows the fusible alloy by energizing and overheating the resistor.
[0004]
[Problems to be solved by the invention]
The above-mentioned fusible alloy type thermal fuse is used as a protective element in home electric appliances such as heat insulation kotatsu and rice cookers, OA equipment such as liquid crystal televisions and copying equipment, and lighting equipment. Among these, a fusible alloy having an operating temperature in the range of 98 to 88 ° C includes a conventional 52Bi-32Pb-16Sn (wt%) ternary alloy (98 ° C), 42.5In-38.6Sn-12.4Cd-6. 0.5Ag (wt%) quaternary alloy (94 ° C), 44In-42Sn-14Cd (wt%) ternary alloy (93 ° C), 50.5Bi-31Pb-15.5Sn-3In (wt%) quaternary alloy ( 90 ° C), 48Bi-30Pb-15Sn-7In (wt%) quaternary alloy (84 ° C), 42-50In-10-10Cd-0.8-5Zn-Remaining Sn (wt%) quaternary alloy (85 ° C) Some of them contain 10% by weight or more of lead and cadmium, which are heavy metals harmful to the human body. Recently, harmful metals eluted from the discarded electric and electronic equipment by the action of rainwater and cause serious pollution to the groundwater have become a global environmental problem, and the improvement of fusible alloys has been required. I have.
[0005]
Further, the fusible alloy of the fusible alloy type thermal fuse is preferably a eutectic alloy composition having a single melting point if possible because liquefaction proceeds at a specific temperature to lead to spheroidization and fusing. Furthermore, from the characteristics of the thermal fuse mounted in series with the power supply circuit, the internal resistance of the thermal fuse does not change even after long-term high-temperature storage, and the specific resistance is 0.79 mΩ · mm or less. It is also desirable from the viewpoint of stability of surface and operating temperature.
[0006]
When an alloy containing no Pb or Cd and having a melting temperature of 110 ° C. or less is designed, a Bi—In binary alloy system is well known (for example, 109% of 67.4 Bi-32.6 In (% by weight)). .7 ° C. composition, 88.7 ° C. the composition of 50Bi-50in (wt%), none of 72.7 ° C. composition) these existing composition of 33.3Bi-66.7In (wt%), BiIn, _Bi 5 an in _3. Because of its eutectic composition with BiIn ₂ intermetallic compound, its mechanical strength is weak, and its specific resistance when incorporated in a thermal fuse is 0.79 mΩ · mm or more. Has a disadvantage that it is difficult to use it as it is.
[0007]
An object of the present invention is to provide an environment-friendly lead-free alloy-type thermal fuse that does not use Pb and Cd as the fusible alloy so as not to cause a problem due to Pb and Cd.
[0008]
[Means for Solving the Problems]
The fusible alloy composition in the lead-free alloy type thermal fuse according to the present invention is not only capable of improving the mechanical strength by adding a suitable amount of Ag to the Bi-In binary alloy system, but also improving the mechanical strength by improving the crystal structure. It is a Bi-In-Ag ternary alloy whose specific resistance is suppressed to 0.79 mΩ · mm or less. Regarding the amount of Ag to be added, AgIn2 is generated by adding Ag excessively, and the solid-liquid coexistence region is increased. If the amount of Ag is too small, the effect of adding Ag cannot be obtained. The preferred range is determined for the composition of Bi-In.
[0009]
In the lead-free alloy type thermal fuse according to claim 1 of the present invention, the thermosensitive element may be composed of 64% to 69% by weight of Bi, 0.05% to 0.3% by weight of Ag, and the balance of In. The use of a molten alloy enables a thermal fuse having an operating temperature of 107 to 109 ° C.
[0010]
In the lead-free alloy type thermal fuse according to claim 2 of the present invention, Bi may be made of 47% by weight to 55% by weight, Ag of 0.05% by weight to 0.2% by weight, and the balance of In. The use of a molten alloy enables a thermal fuse having an operating temperature of 87 to 97 ° C.
[0011]
In the lead-free alloy type thermal fuse according to claim 3 of the present invention, the thermosensitive element may be composed of 32% to 37% by weight of Bi, 0.01% to 0.1% by weight of Ag, and the balance of In. The use of a molten alloy enables a thermal fuse having an operating temperature of 70 to 73 ° C.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment according to the present invention will be described with reference to FIG. FIG. 1 is a longitudinal sectional view showing a lead-free alloy type thermal fuse according to the present invention, which is called an axial type thermal fuse.
[0013]
In the axial type thermal fuse shown in FIG. 1, after a fusible alloy 3 is joined by resistance welding between terminal leads 1 and 2 made of Sn—Cu plated copper wire, the fusible alloy 3 is made of rosin, wax, and activator. This is formed by covering with a flux 4, inserting into an alumina ceramic insulator tube 5, and sealing the case ends with epoxy-based sealing resins 6 and 7, respectively. The Sn-Cu-plated copper wires of the terminal leads 1 and 2 can be changed to Ag-plated copper wires, Sn-plated copper wires, Ni-plated copper wires, and the like, if necessary, and are limited to Sn-Cu-plated copper wires. is not.
[0014]
In the thermal fuse having such a configuration, a fusible alloy 3 having a wire diameter of 0.4 to 0.7 mm can be used, and a rectangular piece of tape-like alloy having the same sectional area can be used if necessary.
[0015]
The fusible alloy used in the thermal fuse of the present invention is manufactured by extruding an alloy ingot, and then can be rolled into a tape if necessary.
[0016]
In addition, the wire diameter of the fusible alloy 3 can be set to φ0.4 mm or less as required, and further changed to φ0.7 mm or more as required, without departing from the spirit of the present invention in the future. You can also.
[0017]
Further, the lead-free alloy type thermal fuse according to the present invention is not limited to an axial type thermal fuse, but may be used for a thermal fuse called a radial type thermal fuse, a thin type thermal fuse, or a thermal fuse having a built-in resistor. Yes, but not limited to a particular format.
[0018]
【Example】
Table 1 shows examples of the present invention and comparative examples. Table 1 shows the fusible alloy compositions and their solidus temperatures, liquidus temperatures, and solid-liquid coexistence regions in the respective Examples and Comparative Examples. (° C.) and liquidus temperature (° C.), and the difference between the liquidus temperature and the solid phase temperature is called a solid-liquid coexistence area (° C.). When the solid-liquid coexistence region is lower than 10 ° C., the fusible alloy can be used as a temperature-sensitive element of a thermal fuse. Therefore, the fusible alloy of the example in which the solid-liquid coexistence region is less than 10 ° C. has good operating characteristics in the thermal fuse of the embodiment. Hereinafter, operation characteristics of the example and the comparative example will be described.
[Table 1]

[0019]
(Example 1-4) A φ0.6 mm wire having a composition of 66.70% by weight of Bi, 33.07% by weight of In, and 0.23% by weight of Ag according to claim 1 was prepared by extrusion. Then, this alloy wire was applied to the thermal fuse of the embodiment. When operated in a thermostatic chamber (gas phase) in which the temperature rises at a rate of 1 ° C./min while applying a detection current of 10 mA to the 30 thermal fuses of Examples 1-4, the operating temperature range is 108 ± 2 ° C. Met. In addition, each of the ten thermal fuses of Example 1-4 stored at 88 ° C. for 500 hours, 1000 hours, and 2000 hours, respectively, was connected by a voltage drop method so as to eliminate the contact resistance. Was measured at a measurement current of 100 mA, and it was found that the specific resistance could be maintained in the range of 0.63 ± 0.2 mΩ · mm. Further, when each of these 10 pieces was operated in a constant temperature bath (gas phase) in which the temperature was raised at a rate of 1 ° C./min, it was found that the initial range of the operating temperature of 108 ± 2 ° C. could be maintained even after high-temperature storage.
[0020]
(Example 2-2) A φ0.6 mm wire having a composition of 53.00% by weight of Bi, 46.86% by weight of In, and 0.14% by weight of Ag according to claim 2 was prepared by extrusion. Then, this alloy wire was applied to the thermal fuse of the embodiment. When operated in a thermostatic chamber (gas phase) in which the temperature rises at a rate of 1 ° C./min while applying a detection current of 10 mA to the 30 thermal fuses of Example 2-2, the operating temperature range is 96 ± 2 ° C. Met. Further, each of the ten thermal fuses of Example 2-2 stored at 76 ° C. for 500 hours, 1000 hours, and 2000 hours, respectively, was connected by a voltage drop method so as to eliminate the contact resistance, and between the leads at a point of 25 mm including the main body. Was measured at a measurement current of 100 mA, and it was found that the specific resistance could be maintained in the range of 0.55 ± 0.2 mΩ · mm. Furthermore, when each of these 10 pieces was operated in a thermostatic chamber (gas phase) in which the temperature was raised at a rate of 1 ° C./min, it was found that the initial temperature range of 96 ± 2 ° C. could be maintained even after high-temperature storage.
[0021]
(Example 2-5) A φ0.6 mm line having a composition of 49.70% by weight of Bi, 50.22% by weight of In, and 0.08% by weight of Ag according to claim 2 was prepared by extrusion. Then, this alloy wire was applied to the thermal fuse of the embodiment. When operated in a thermostatic chamber (gas phase) in which the temperature rises at a rate of 1 ° C./min while applying a detection current of 10 mA to the 30 thermal fuses of Example 2-5, the operating temperature range is 89 ± 2 ° C. Met. In addition, each of the ten thermal fuses of Example 2-5 stored at 69 ° C. for 500 hours, 1000 hours, and 2000 hours, respectively, was connected by a voltage drop method so as to eliminate contact resistance. Was measured at a measurement current of 100 mA, and it was found that the specific resistance could be maintained in the range of 0.55 ± 0.2 mΩ · mm. Furthermore, when each of these 10 pieces was operated in a constant temperature bath (gas phase) in which the temperature was increased at a rate of 1 ° C./min, it was found that the initial range of the operating temperature of 89 ± 2 ° C. could be maintained even after high-temperature storage.
[0022]
(Example 2-9) A φ0.6 mm wire having a composition of 48.50% by weight of Bi, 51.43% by weight of In, and 0.07% by weight of Ag according to claim 2 was produced by extrusion. Then, this alloy wire was applied to the thermal fuse of the embodiment. When operated in a thermostatic chamber (gas phase) in which the temperature rises at a rate of 1 ° C./min while applying a detection current of 10 mA to the 30 thermal fuses of Example 2-9, the operating temperature range is 88 ± 2 ° C. Met. In addition, each of the 10 thermal fuses of Example 2-9 stored at 68 ° C. for 500 hours, 1000 hours, and 2000 hours, respectively, was connected by a voltage drop method so as to eliminate the contact resistance. Was measured at a measurement current of 100 mA, and it was found that the specific resistance could be maintained in the range of 0.47 ± 0.2 mΩ · mm. Furthermore, when each of these 10 pieces was operated in a constant temperature bath (gas phase) in which the temperature was raised at a rate of 1 ° C./min, it was found that the initial range of the operating temperature of 88 ± 2 ° C. could be maintained even after high-temperature storage.
[0023]
(Example 3-2) A φ0.6 mm wire having a composition of 34.20% by weight of Bi, 65.78% by weight of In, and 0.02% by weight of Ag according to claim 3 was produced by extrusion. This alloy wire was applied to the thermal fuse of the embodiment. When operated in a thermostatic chamber (gas phase) in which the temperature rises at a rate of 1 ° C./min while applying a detection current of 10 mA to the 30 thermal fuses of Example 3-2, the operating temperature range is 73 ± 2 ° C. Met. In addition, each of the ten thermal fuses of Example 3-2 stored at 53 ° C. for 500 hours, 1000 hours, and 2000 hours, respectively, was connected by a voltage drop method so as to eliminate the contact resistance. Was measured at a measurement current of 100 mA, and it was found that the specific resistance could be maintained in the range of 0.32 ± 0.2 mΩ · mm. Furthermore, when each of these 10 pieces was operated in a constant temperature bath (gas phase) in which the temperature was raised at a rate of 1 ° C./min, it was found that the initial range of the operating temperature of 73 ± 2 ° C. was maintained even after high-temperature storage.
[0024]
[Comparative example]
(Comparative Example 1-1) An alloy composition (66.53Bi-33.07In-0.4Ag (% by weight)) in which the composition of Bi and In was set to claim 1 and the amount of Ag was 0.4% by weight was as follows. Since the solid-liquid coexistence region was 26.7 ° C. and 10 ° C. or more, and the temperature range from the start of melting to the completion of melting was too wide, it was not practically used as a thermal fuse. Similarly, the solid-liquid coexistence range of the alloy composition (66.43Bi-33.07In-0.5Ag (% by weight)) in which the amount of Ag was 0.5% by weight was 37.3 ° C., and it could not be used as a thermal fuse. Was. An attempt was made to extrude a φ0.6 mm wire of an alloy composition (66.92Bi-33.07In-0.01Ag (% by weight)) in which the amount of Ag was 0.05% by weight or less. Was inferior and too brittle to produce. The effective Ag content in the composition range of Bi and In in claim 1 was 0.05 to 0.3% by weight.
[0025]
(Comparative Example 2-1) The alloy composition (52.84Bi-46.86In-0.3Ag (% by weight)) in which the composition of Bi and In was set in the range of claim 2 and the amount of Ag was 0.3% by weight was as follows. Since the solid-liquid coexistence region was 10.1 ° C. or higher and 10 ° C. or higher, the temperature range from the start of melting to the completion of melting was too wide, and thus it was not practical as a temperature fuse. Similarly, the solid-liquid coexistence range of the alloy composition (52.74Bi-46.86In-0.4Ag (% by weight)) in which the amount of Ag was set to 0.4% by weight was 23.1 ° C., so that it could not be used as a thermal fuse. Was. An attempt was made to extrude a φ0.6 mm wire of a composition (53.13Bi-46.86In-0.01Ag (% by weight)) in which the amount of Ag was 0.05% by weight or less. It could not be produced because it was inferior and brittle. The effective Ag compounding amount in the composition range of Bi and In in claim 2 was 0.05 to 0.2% by weight.
[0026]
(Comparative Example 3-1) The alloy composition (34.2Bi-65.6In-0.2Ag (% by weight)) in which the composition of Bi and In is set in the range of claim 3 and the amount of Ag is 0.2% by weight is as follows. Since the solid-liquid coexistence range was 21.7 ° C. and 10 ° C. or higher, the temperature range from the start of melting to the completion of melting was too wide, and thus it was not practical as a temperature fuse. Similarly, the solid-liquid coexistence range of the alloy composition (34.2Bi-65.5In-0.3Ag (% by weight)) in which the amount of Ag was set to 0.3% by weight was 31 ° C, so that it could not be used as a thermal fuse. An attempt was made to extrude a φ0.6 mm wire having a composition (34.200 Bi-65.795In-0.005Ag (% by weight)) in which the amount of Ag was 0.01% by weight or less, but the alloy was soft. Because of too much deformation during assembly, a thermal fuse could not be produced. The effective amount of Ag in the composition range of Bi and In in claim 3 was 0.01 to 0.1% by weight.
[0027]
【The invention's effect】
As described above, the present invention realizes a highly reliable lead-free alloy type thermal fuse that can operate at 70 to 109 ° C. by using a Bi-In-Ag ternary alloy containing no Pb or Cd. .
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an axial type thermal fuse according to an embodiment of the present invention.
1, 2 terminal lead 3 fusible alloy 4 flux 5 insulating case 6, 7 sealing resin

Claims

In a thermal fuse in which a lead member connected to both ends of a fusible alloy is inserted into a case made of an insulator, and an end from which the lead member is led out from the case made of the insulator is sealed, the fusible alloy A lead-free alloy type thermal fuse characterized by using a fusible alloy having a composition of 64 to 69% by weight of Bi, 0.05 to 0.3% by weight of Ag, and the balance of In.

In a thermal fuse in which a lead member connected to both ends of a fusible alloy is inserted into a case made of an insulator, and an end from which the lead member is led out from the case made of the insulator is sealed, the fusible alloy A lead-free alloy type thermal fuse characterized by using a fusible alloy having a composition of 47% to 55% by weight of Bi, 0.05% to 0.2% by weight of Ag, and the balance of In.

In a thermal fuse in which a lead member connected to both ends of a fusible alloy is inserted into a case made of an insulator, and an end from which the lead member is led out from the case made of the insulator is sealed, the fusible alloy A fusible alloy having a composition of 32 to 37% by weight of Bi, 0.01 to 0.1% by weight of Ag, and the balance of In.