JP4097791B2

JP4097791B2 - Thin temperature fuse

Info

Publication number: JP4097791B2
Application number: JP22228198A
Authority: JP
Inventors: 尚岡本; 朋晋三井
Original assignee: Uchihashi Estec Co Ltd
Current assignee: Uchihashi Estec Co Ltd
Priority date: 1998-07-22
Filing date: 1998-07-22
Publication date: 2008-06-11
Anticipated expiration: 2018-07-22
Also published as: JP2000040453A

Description

【０００１】
【発明の属する技術分野】
本発明は薄型温度ヒュ−ズに関し、リチウムイオン２次電池等の電池の昇温防止に有用なものである。
【０００２】
【従来の技術】
合金型温度ヒュ−ズにおいては、機器の過電流に基づく発熱で低融点可溶合金のヒュ−ズエレメントを溶断させて機器の通電を遮断し機器の異常発熱ひいては火災の発生を未然に防止している。
近来、携帯電話、ノ−トブックパソコン、ビデオカメラ等のパ−ソナルユ−ス電子機器の小型化・薄型化に伴い、その電源である２次電池（リチウムイオン電池、ニッケル水素電池等）も小型化されている。
【０００３】
このリチウムイオン２次電池等では、エネルギ−密度が高く放電時や充電時に相当に大きな電流が流れて昇温する可能性があるので、２次電池の底面または側面に合金型温度ヒュ−ズを配設して昇温防止することが検討されている。
この合金型温度ヒュ−ズに要求される作動温度は８０〜１２０℃である。また電池の小型化に対応して薄型であることが要請される。
そこで、樹脂ベ−スフィルムの片面上に一対の帯状リ−ド導体の先端部を固着し、帯状リ−ド導体の先端間に低融点可溶合金片を接続し、低融点可溶合金片にフラックスを塗布し、樹脂ベ−スフィルムの片面上に樹脂カバ−フィルムを配し、両樹脂フィルム周辺のフィルム間及び樹脂カバ−フィルムと帯状リ−ド導体との間を封止してなる薄型温度ヒュ−ズが提案されている。
【０００４】
【発明が解決しようとする課題】
この薄型温度ヒュ−ズにおいて樹脂フィルムに機械的強度の高いものを使用すれば、それだけベ−スフィルムやカバ−フィルムの厚みを薄くでき薄型化に有利である。通常、樹脂フィルムにおいては延伸により機械的強度、特に引張り強度を高めている。
しかしながら、温度ヒュ−ズにおいては作動以前に機器のヒ−トサイクルにより加熱・冷却され、かかる加熱・冷却の繰返しに対し延伸処理フィルムでは延伸による分子の強制的配向が解除されてそれに伴い収縮を生じるから、上記封止部のシ−ル性低下が懸念される。
このため、上記薄型温度ヒュ−ズの樹脂フィルムには、寸法安定性を優先させて非延伸の樹脂フィルムを使用することが安全であるが、これでは温度ヒュ−ズの薄型化に不利である。
【０００５】
しかしながら、本発明者等においては、薄型温度ヒュ−ズを上記電池昇温防止に使用する場合の作動温度８０〜１２０℃に対し、延伸ポリエチレンテレフタレ−トフィルムであれば、延伸率（熱収縮率）を限定することにより充分な寸法安定性を保証しつつ温度ヒュ−ズを有効に薄型化できることを知った。
【０００６】
本発明の目的は、作動温度が８０〜１２０℃の超薄型温度ヒュ−ズを提供することにある。
【０００７】
〔課題を解決するための手段〕
本発明に係る薄型温度ヒュ−ズは、樹脂ベ−スフィルムの片面上に一対の帯状リ−ド導体の先端部を固着し、帯状リ−ド導体の先端間に低融点可溶合金片を接続し、低融点可溶合金片にフラックスを塗布し、樹脂ベ−スフィルムの片面上に樹脂カバ−フィルムを配し、両樹脂フィルム周辺のフィルム間及び樹脂カバ−フィルムと帯状リ−ド導体との間を封止して温度ヒュ−ズ、または、一対の帯状リ−ド導体の先端部を樹脂ベ−スフィルムにその裏面側から表面側に表出させて固着し、両帯状リ−ド導体の先端表出部間に低融点可溶合金片を接続し、該低融点可溶合金片にフラックスを塗布し、樹脂ベ−スフィルムの表面上に樹脂カバ−フィルムを配し、両樹脂フィルム周辺のフィルム間及び樹脂カバ−フィルムと帯状リ−ド導体との間を封止してなる温度ヒュ−ズ、あるいは、一方の帯状リ−ド導体の先端部を樹脂ベ−スフィルムにその裏面側から表面側に表出させて固着し、他方の帯状リ−ド導体の先端部を樹脂ベ−スフィルムの表面側に固着し、両帯状リ−ド導体の先端間に低融点可溶合金片を接続し、該低融点可溶合金片にフラックスを塗布し、樹脂ベ−スフィルムの表面上に樹脂カバ−フィルムを配し、両樹脂フィルム周辺のフィルム間及び樹脂カバ−フィルムと他方の帯状リ−ド導体との間を封止してなる温度ヒュ−ズにおいて、低融点可溶合金片の固相線温度を８０〜１２０℃、液相線温度を８０〜１２０℃とし、両樹脂フィルムに、ＤＳＣ曲線が前記８０〜１２０℃までの温度では変曲点がなく直線である延伸ポリエチレンテレフタレ−トフィルムを使用したことを特徴とする構成である。
【０００８】
【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の（イ）は本発明に係る温度ヒュ−ズの一例を示している。
図１の（イ）において、１１は樹脂ベ−スフィルム、２は帯状リ−ド導体であり、図１の（ロ）に示すように、各帯状リ−ド導体２，２の先端部を樹脂ベ−スフィルム１１の片面に熱プレスや超音波融着或いは接着剤等で固着してある。
図１の（イ）において、３は帯状リ−ド導体２，２間に溶接により接続した低融点可溶合金片であり、温度ヒュ−ズの作動温度を８０〜１２０℃とするように固相線温度を８０〜１２０℃、液相線温度を８０〜１２０℃としてある。４は低融点可溶合金片に塗布したフラックス、１２は樹脂ベ−スフィルム１１の表面上に配した樹脂カバ−フィルムであり、樹脂カバ−フィルムの周辺のフィルム間及び樹脂カバ−フィルムと帯状リ−ド導体との間を熱プレスや超音波融着或いは接着剤等で封止してある。
【０００９】
上記樹脂ベ−スフィルム及び樹脂カバ−フィルムには、熱収縮率（ＪＩＳＣ２３１８−７２）が３％以下の一軸または二軸延伸ポリエチレンテレフタレ−トフィルムを使用してある。
【００１０】
周知の通り、延伸したプラスチックフィルムにおいては、分子鎖が強制的に配向拘束されているから加熱すると、その拘束が解除されて収縮する。
しかしながら、熱収縮率が３％以下の延伸ポリエチレンテレフタレ−トフィルムにおいては、図７の（イ）に示すＤＳＣ曲線（加熱速度１０℃／min)から明らかなように、２４６．１℃で状態が変化し始め、２６３．０℃で完全に溶融するが、加熱開始後から温度８０〜１２０℃に至るまでの間の変化には実質上変曲点がなく直線的であり〔直線が下降勾配になっているのは、延伸ポリエチレンテレフタレ−トフィルムと示差走査熱量計の基準試料（α−アルミナ）との熱容量の差が主な理由である〕、温度８０〜１２０℃に至るまでの延伸ポリエチレンテレフタレ−トフィルムの熱収縮は僅少である。
従って、樹脂ベ−スフィルムや樹脂カバ−フィルムの熱的変形に起因するシ−ル性低下等を排除でき、温度ヒュ−ズの確実な作動を保証できる。
【００１１】
また、ポリエチレンテレフタレ−トフィルムの強度（特に、引張り強度）を熱収縮率にして１．５％程度の延伸で非延伸のものに較べて１．４倍程度にでき、従ってフィルム厚みを１／１．４倍程度にできる。従って、例えば、帯状リ−ド導体の厚みを１００μｍ、低融点可溶合金片をφ３００μｍとする場合、樹脂ベ−スフィルム及び樹脂カバ−フィルムに厚みを２８０μｍの非延伸ポリエチレンテレフタレ−トフィルムを使用した従来の全厚み９６０μｍのものに較べ、本発明によれば全厚みをほぼ８００μｍにでき充分に薄厚にできる。
【００１２】
上記帯状リ−ド導体２には、例えば銅線、アルミニウム線、ニッケル線、銅メッキ鉄線等の圧延体、この圧延体に錫めっきを施したもの等を使用でき、厚みは通常５０μｍ〜２５０μｍ、好ましくは１００μｍ、巾は通常２〜５ｍｍ、好ましくは３ｍｍとされる。
【００１３】
上記延伸ポリエチレンテレフタレ−トフィルムの厚みは、通常５０〜４００μｍ、好ましくは２００μｍとされる。
【００１４】
上記低融点可溶合金片３には、▲１▼温度ヒュ−ズの作動温度を８０〜１２０℃とすること、▲２▼温度ヒュ−ズの超薄型化・超小型化のために低融点可溶合金片の断面積を０．０３〜０．１３ｍｍ²してしても負荷電流のもとでのジュ−ル発熱を実質上排除できる低比抵抗とすることから、固相線温度１００〜１２０℃、液相線温度８０〜１２０℃、比抵抗（１０〜３０μΩcm）の合金組成が使用され、例えばＩｎ３０〜７５重量％、Ｓｎ５〜５０重量％、Ｃｄ０．５〜２５重量％、好ましくはＩｎ４０〜６０重量％、Ｓｎ２５〜５０重量％、Ｃｄ１０〜１５重量％、特に好ましくはＩｎ４０〜５５重量％、Ｓｎ３０〜４６重量％、Ｃｄ１４〜１５重量％の合金組成を使用できる。
この比抵抗をさらに低くするために、合金組成にＡｕ、Ａｇ、Ｃｕ、Ａｌのうちの１種または２種以上を合計０．１〜５重量％添加することができる。
【００１５】
かかる低融点可溶合金片によれば、低融点可溶合金片の断面積を０．０３〜０．１３ｍｍ²と小さくしても負荷電流による低融点可溶合金片の発熱を実質上排除でき、低融点可溶合金片の幅を１．４ｍｍとする場合、低融点可溶合金片の厚みを０．０２ｍｍ〜０．０９３ｍｍの超薄型にでき、温度ヒュ−ズ本体の厚み中、低融点可溶合金片が占める部分を僅少にとどめることができる。
【００１６】
図２の（イ）は、本発明に係る温度ヒュ−ズの別例を示し、図２の（ロ）のように一対の帯状リ−ド導体２，２の先端部を熱プレス等で樹脂ベ−スフィルム１１にその裏面側から表面側に表出させて固着し、次いで、これらの固着帯状リ−ド導体２，２の表出部間に低融点可溶合金片３を抵抗溶接等で接合してある。他の構成は図１に示したものと実質的に同じとし、樹脂ベ−スフィルム１１及び樹脂カバ−フィルム１２には熱収縮率が３％以下の一軸または二軸延伸ポリエチレンテレフタレ−トフィルムを使用してある。
図２において、図１と同一の符号は同一の構成要素を示している。
【００１７】
図３の（イ）は、本発明に係る温度ヒュ−ズの他の別例を示し、図３の（ロ）のように一方の帯状リ−ド導体２１の先端部を熱プレス等で延伸ポリエチレンテレフタレ−トフィルムのベ−スフィルム１１にその裏面側から表面側に表出させて固着し、他方の帯状リ−ド導体２の先端部を樹脂ベ−スフィルム１１の表面に熱プレス等で固着し、更に、図３の（イ）において、両帯状リ−ド導体２，２１の先端間に低融点可溶合金片３を抵抗溶接等で接合し、更に低融点可溶合金片３上にフラックス４を塗布し、次いで、樹脂ベ−スフィルム１１の片面上に延伸ポリエチレンテレフタレ−トフィルムのカバ−フィルム１２を配し、樹脂カバ−フィルム１２の周辺と樹脂ベ−スフィルム１１との間及び樹脂カバ−フィルム１２と他方の帯状リ−ド導体２との間をヒ−トシ−ルまたは超音波融着或いはレ−ザ照射により封止してある。
【００１８】
本発明に係る薄型温度ヒュ−ズは、例えばリチウムイオン二次電池を異常発熱から保護するために使用できる。
【００１９】
図４はリチウムイオン二次電池を示し、セパレ−タ５１を介在させた正極５２と負極５３とのスパイラル巻回体低融点可溶合金片を負極缶５４に収容して負極５３と負極缶５４の底面とを電気的に導通し、負極缶５４内の上端に正極集電極５５を配設して正極５２をこの集電極５５に電気的に導通し、負極缶５４の上端部５４１を防爆弁板外５６の外周端部及び正極蓋５７の外周端部にパッキング５８を介してかしめ加工し、防爆弁板５６の中央凹部を正極集電極５９に電気的に導通してある。
【００２０】
本発明に係る係る温度ヒュ−ズを上記電池に取付けるには、電池の負極缶に一方の帯状リ−ド導体及び温度ヒュ−ズ本体を密接させると共にその一方の帯状リ−ド導体と負極缶との間を電気的に接続し、他方の帯状リ−ド導体を負極缶から離隔や絶縁フィルムの介在により絶縁して当該電池に直列に挿入することができる。
【００２１】
また、温度ヒュ−ズをリチウムイオン二次電池の防爆弁板５６と正極蓋５７との間の空間に配し、防爆弁板５６の外周端部と正極蓋５７の外周端部との間に絶縁スペ−サリングｒを介在させ、一方の帯状リ−ド導体２を防爆弁板５６の外周端部と絶縁スペ−サリングｒとで挾持し、他方の帯状リ−ド導体２を正極蓋５７の外周端部と絶縁スペ−サリングｒとで挾持して電池内に直列に組み込むこともできる。
【００２２】
図５の（イ）及び図５の（ロ）〔図５の（イ）におけるロ−ロ断面図〕は、本発明に係る温度ヒュ−ズの上記とは別の実施例を示している。
図５において、Ｆはフレ−ムを示し、図６の（イ）に示す環状部２０１の内周に一方の帯状リ−ド導体２１を有する一方の箔状電極ｆ₁と、図６の（ロ）に示す環状の延伸ポリエチレンテレフタレ−トフィルムのスペ−サフィルムｓと、図６の（ハ）に示す環状部２００の内周に他方の帯状リ−ド導体２を有する箔状電極ｆ₂とをリ−ド部２，２１を１８０°互い違いにして重畳してあり、これらの箔状電極ｆ₁，ｆ₂と樹脂スペ−サフィルムｓの界面の接着には熱融着等を使用できる。
【００２３】
図５において、Ａはフレ−ムＦの中央空間に配した温度ヒュ−ズ本体であり、一方の帯状リ−ド導体２１の先端部を延伸ポリエチレンテレフタレ−トフィルムのベ−スフィルム１１の一面に固着すると共に該フィルム１１の一面より他面に局部的に表出させ、他方の帯状リ−ド導体２の先端部を前記ベ−スフィルム１１の他面に固着し、該先端部と前記局部的に表出された一方の帯状リ−ド導体２１先端部分との間に低融点可溶合金片３を溶接等で接続し、該低融点可溶合金片３にフラックス４を塗布し、このフラックス塗布低融点可溶合金片上に延伸ポリエチレンテレフタレ−トフィルムのカバ−フィルム１２を配し、樹脂カバ−フィルム１２周辺の樹脂ベ−スフィルム１１と樹脂カバ−フィルム１２との間及び樹脂カバ−フィルム１２と他方の帯状リ−ド導体２との間をヒ−トシ−ルまたは超音波融着或いはレ−ザ照射により封止してある。
【００２４】
この温度ヒュ−ズを図４に示す電池に組み込むには、前記絶縁スペ−サリングｒを介することなく防爆弁板５６の外周端部と正極蓋５７の外周端部との間に挾持して防爆弁板５６とフレ−ムＦの箔状電極ｆ₁との電気的接触→箔状電極ｆ₁のリ−ド導体２１→低融点可溶合金片３→箔状電極ｆ₀のリ−ド導体２→フレ−ムＦの箔状電極ｆ₀と正極蓋５７との電気的接触により、電池に温度ヒュ−ズを電気的に直列に接続することができる。
【００２５】
【実施例】
〔実施例〕
延伸ポリエチレンテレフタレ−トフィルムには、厚さ２００μｍ、熱収縮率１．５％のものを使用した。この延伸ポリエチレンテレフタレ−トフィルムのＤＳＣ曲線は図７の（イ）に示す通りである（ただし、示差走査熱量計には理学電機株式会社製のものを使用した。基準試料はα−アルミナ、雰囲気ガスはＮ₂、加熱速度は１０℃／min、サンプリング１．０sec、試料量は１５．０mg)。
薄型温度ヒュ−ズは図１の構成とし、樹脂ベ−スフィルム及び樹脂カバ−フィルムの平面寸法は５ｍｍ×７ｍｍとし、帯状リ−ド導体には厚み１００μｍ、巾３ｍｍのニッケル帯状体を使用し、低融点可溶合金片には、Ｉｎ４０重量％，Ｓｎ４６重量％，Ｃｄ１４重量％，断面積０．０６７ｍｍ²，厚み４８μｍのものを使用し、フラックスにはロジンを主成分とするものを使用した。また、封止及び接着はヒ−トシ−ルとした。
【００２６】
〔比較例〕
樹脂ベ−スフィルム及び樹脂カバ−フィルムに図７の（ロ）に示すＤＳＣ曲線の厚み２００μｍの非延伸ポリエチレンテレフタレ−トフィルムを使用した以外、実施例に同じとした。
【００２７】
実施例及び比較例の初期引張り強度を測定したところ、後者は前者の７０％前後であった。
また、実施例及び比較例につき加熱に対する寸法安定性を試験したところ、両者に差は認められず、何れも安定であった。
【００２８】
【発明の効果】
本発明に係る温度ヒュ−ズは、作動温度が８０〜１２０℃の合金型温度ヒュ−ズにおいて、良好な作動性を保証しつつ超薄厚化を可能としたものであり、２次電池の昇温防止用温度ヒュ−ズとしての超薄型・超小型合金型温度ヒュ−ズを提供できる。
【図面の簡単な説明】
【図１】本発明に係る温度ヒュ−ズの一例を示す図面である。
【図２】本発明に係る温度ヒュ−ズの上記とは異な一例を示す図面である。
【図３】本発明に係る温度ヒュ−ズの上記とは異な一例を示す図面である。
【図４】本発明に係る温度ヒュ−ズの使用状態の一例を示す図面である。
【図５】本発明に係る温度ヒュ−ズの上記とは異な一例を示す図面である。
【図６】図５に示す温度ヒュ−ズに使用されるフレ−ムを示す図面である。
【図７】図７の（イ）は本発明の実施例で使用した延伸ポリエチレンテレフタレ−トフィルムのＤＳＣ曲線、図７の（ロ）は比較例で使用した非延伸ポリエチレンテレフタレ−トフィルムのＤＳＣ曲線である。
【符号の説明】
１１延伸ポリエチレンテレフタレ−トフィルム
１２延伸ポリエチレンテレフタレ−トフィルム
２帯状リ−ド導体
２１帯状リ−ド導体
３低融点可溶合金片
４フラックス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin temperature fuse and is useful for preventing temperature rise of a battery such as a lithium ion secondary battery.
[0002]
[Prior art]
In the alloy type temperature fuse, heat generation due to the overcurrent of the equipment melts the fuse element of the low-melting-point soluble alloy to cut off the power supply to the equipment, thereby preventing abnormal heat generation of the equipment and fire. ing.
Recently, along with the downsizing and thinning of personal-use electronic devices such as mobile phones, notebook PCs, and video cameras, secondary batteries (lithium-ion batteries, nickel-metal hydride batteries, etc.) that are power supplies have also been downsized. Has been.
[0003]
In this lithium ion secondary battery, etc., the energy density is high and there is a possibility that a considerably large current flows during discharging or charging, so that the temperature rises. Therefore, an alloy-type temperature fuse is provided on the bottom or side of the secondary battery. Arrangement to prevent temperature rise has been studied.
The operating temperature required for this alloy type temperature fuse is 80-120 ° C. In addition, it is required to be thin in response to the miniaturization of the battery.
Therefore, the tip of the pair of strip-shaped lead conductors is fixed on one surface of the resin-based film, and a low melting point soluble alloy piece is connected between the tips of the strip-shaped lead conductors. Flux is applied to the resin base film, a resin cover film is disposed on one side of the resin base film, and the gap between the two resin films and between the resin cover film and the strip-shaped lead conductor is sealed. A thin temperature fuse has been proposed.
[0004]
[Problems to be solved by the invention]
If a resin film having a high mechanical strength is used in this thin temperature fuse, the thickness of the base film or cover film can be reduced accordingly, which is advantageous for thinning. Usually, in a resin film, mechanical strength, particularly tensile strength, is increased by stretching.
However, in the temperature fuse, it is heated and cooled by the heat cycle of the equipment before the operation, and in the stretched film, the forced orientation of the molecules due to stretching is released and the shrinkage is caused accordingly. As a result, there is a concern that the sealing property of the sealing portion is lowered.
For this reason, it is safe to use a non-stretched resin film with priority given to dimensional stability for the resin film of the above-mentioned thin temperature fuse, but this is disadvantageous for making the temperature fuse thin. .
[0005]
However, in the present inventors, if the stretched polyethylene terephthalate film is used for the operating temperature of 80 to 120 ° C. when the thin temperature fuse is used for preventing the temperature rise of the battery, the stretch rate (heat shrinkage rate) It was found that the temperature fuse can be effectively reduced in thickness while guaranteeing sufficient dimensional stability.
[0006]
An object of the present invention is to provide an ultra-thin temperature fuse having an operating temperature of 80 to 120 ° C.
[0007]
[Means for solving the problems]
The thin temperature fuse according to the present invention has a pair of strip-shaped lead conductors fixed on one side of a resin base film, and a low melting point soluble alloy piece between the tips of the strip-shaped lead conductors. Connect, apply flux to low melting point soluble alloy piece, place resin cover film on one side of resin base film, and between resin film peripheral film and resin cover film and strip lead conductor The temperature fuse or the tip of a pair of strip-shaped lead conductors is fixed to the resin base film by exposing it from the back side to the front side. A low melting point soluble alloy piece is connected between the exposed ends of the conductors, a flux is applied to the low melting point soluble alloy piece, and a resin cover film is disposed on the surface of the resin base film. Seal between the film around the resin film and between the resin cover film and the strip-shaped lead conductor. The tip of one of the belt-like lead conductors is fixed to the resin base film by exposing the tip of the belt-like lead conductor from the back side to the front side. Is fixed to the surface side of the resin base film, a low melting point soluble alloy piece is connected between the tips of the two strip-shaped lead conductors, a flux is applied to the low melting point soluble alloy piece, In the temperature fuse formed by placing a resin cover film on the surface of the film film and sealing between the films around both resin films and between the resin cover film and the other strip-shaped lead conductor, The solidus temperature of the melting point soluble alloy piece is 80 to 120 ° C., the liquidus temperature is 80 to 120 ° C., and the DSC curves of both resin films are straight and have no inflection point at the temperature of 80 to 120 ° C. in a stretched polyethylene terephthalate - for using Tofirumu A structure characterized.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A shows an example of a temperature fuse according to the present invention.
In FIG. 1 (a), 11 is a resin base film, 2 is a strip-shaped lead conductor, and as shown in (b) of FIG. It is fixed to one surface of the resin base film 11 by hot press, ultrasonic fusion, adhesive or the like.
In FIG. 1A, reference numeral 3 denotes a low-melting-point soluble alloy piece connected by welding between the strip-shaped lead conductors 2 and 2, and is fixed so that the operating temperature of the temperature fuse is 80 to 120 ° C. The phase line temperature is 80 to 120 ° C, and the liquidus temperature is 80 to 120 ° C. 4 is a flux applied to the low melting point soluble alloy piece, and 12 is a resin cover film disposed on the surface of the resin base film 11, between the films around the resin cover film and between the resin cover film and the belt shape. The lead conductor is sealed with a hot press, ultrasonic fusion, adhesive, or the like.
[0009]
A uniaxial or biaxially stretched polyethylene terephthalate film having a heat shrinkage rate (JIS C2318-72) of 3% or less is used for the resin base film and the resin cover film.
[0010]
As is well known, in a stretched plastic film, molecular chains are forcibly restrained in orientation, so when heated, the restraints are released and shrink.
However, in the stretched polyethylene terephthalate film having a heat shrinkage rate of 3% or less, the state is observed at 246.1 ° C. as is apparent from the DSC curve (heating rate 10 ° C./min) shown in FIG. It begins to change and melts completely at 263.0 ° C., but the change between the start of heating and the temperature from 80 to 120 ° C. is substantially linear with no inflection point. This is mainly due to the difference in heat capacity between the stretched polyethylene terephthalate film and the reference sample (α-alumina) of the differential scanning calorimeter], and the stretched polyethylene terephthalate up to a temperature of 80 to 120 ° C. The thermal shrinkage of the turret film is negligible.
Accordingly, it is possible to eliminate a decrease in sealing property due to thermal deformation of the resin base film or the resin cover film, and to ensure a reliable operation of the temperature fuse.
[0011]
Further, the strength (particularly, tensile strength) of the polyethylene terephthalate film can be increased by about 1.4% compared to the non-stretched film by stretching it by about 1.5% with a heat shrinkage ratio. It can be about 1.4 times. Therefore, for example, when the thickness of the strip-shaped lead conductor is 100 μm and the low melting point soluble alloy piece is φ300 μm, an unstretched polyethylene terephthalate film having a thickness of 280 μm is used for the resin base film and the resin cover film. Compared with the conventional one having a total thickness of 960 μm, according to the present invention, the total thickness can be reduced to about 800 μm and sufficiently reduced.
[0012]
As the strip-shaped lead conductor 2, for example, a rolled body such as a copper wire, an aluminum wire, a nickel wire, a copper-plated iron wire, or the like obtained by tin-plating the rolled body can be used, and the thickness is usually 50 to 250 μm. The width is preferably 100 μm and the width is usually 2 to 5 mm, preferably 3 mm.
[0013]
The stretched polyethylene terephthalate film has a thickness of usually 50 to 400 μm, preferably 200 μm.
[0014]
The low-melting-point soluble alloy piece 3 has (1) a temperature fuse operating temperature of 80 to 120 ° C., and (2) a low temperature fuse for ultra-thinness and miniaturization. Even if the melting point soluble alloy piece has a cross-sectional area of 0.03 to 0.13 mm ^2, it has a low specific resistance that can substantially eliminate the Joule heat generation under load current. An alloy composition having a temperature of 100 to 120 ° C., a liquidus temperature of 80 to 120 ° C., and a specific resistance (10 to 30 μΩcm) is used, for example, In 30 to 75 wt%, Sn 5 to 50 wt%, Cd 0.5 to 25 wt%, preferably Can use an alloy composition of In 40 to 60 wt%, Sn 25 to 50 wt%, Cd 10 to 15 wt%, particularly preferably In 40 to 55 wt%, Sn 30 to 46 wt%, and Cd 14 to 15 wt%.
In order to further reduce the specific resistance, one or more of Au, Ag, Cu, and Al can be added to the alloy composition in a total amount of 0.1 to 5% by weight.
[0015]
According to such a low melting point soluble alloy piece, even if the sectional area of the low melting point soluble alloy piece is reduced to 0.03 to 0.13 mm ² , the heat generation of the low melting point soluble alloy piece due to the load current can be substantially eliminated. When the width of the low-melting-point soluble alloy piece is 1.4 mm, the thickness of the low-melting-point soluble alloy piece can be made ultra-thin from 0.02 mm to 0.093 mm. The portion occupied by the melting point soluble alloy piece can be kept small.
[0016]
2 (a) shows another example of the temperature fuse according to the present invention. As shown in FIG. 2 (b), the tips of the pair of strip-shaped lead conductors 2 and 2 are resinated by hot pressing or the like. The base film 11 is exposed and fixed from the back surface side to the front surface side, and then the low melting point soluble alloy piece 3 is resistance-welded between the exposed portions of the fixed strip-shaped lead conductors 2 and 2. Are joined together. Other configurations are substantially the same as those shown in FIG. 1, and the resin base film 11 and the resin cover film 12 are made of a uniaxial or biaxially stretched polyethylene terephthalate film having a heat shrinkage rate of 3% or less. It is used.
2, the same reference numerals as those in FIG. 1 denote the same components.
[0017]
FIG. 3 (a) shows another example of the temperature fuse according to the present invention. As shown in FIG. 3 (b), the leading end of one strip-shaped lead conductor 21 is stretched by hot press or the like. A polyethylene terephthalate film is fixed to the base film 11 by being exposed from the back side to the front side, and the tip of the other strip-shaped lead conductor 2 is hot pressed on the surface of the resin base film 11 or the like. Further, in FIG. 3 (a), the low melting point soluble alloy piece 3 is joined between the ends of the strip-shaped lead conductors 2 and 21 by resistance welding or the like, and the low melting point soluble alloy piece 3 is further bonded. The flux 4 is applied on the resin base film 11, and then a stretched polyethylene terephthalate film cover film 12 is disposed on one surface of the resin base film 11, and the periphery of the resin cover film 12 and the resin base film 11 Between the resin cover film 12 and the other strip lead Between the 2 heat - tosylate - le or ultrasonic welding or Le - it is sealed by THE irradiation.
[0018]
The thin temperature fuse according to the present invention can be used, for example, to protect a lithium ion secondary battery from abnormal heat generation.
[0019]
FIG. 4 shows a lithium ion secondary battery, in which a spiral wound body low melting point soluble alloy piece of a positive electrode 52 and a negative electrode 53 with a separator 51 interposed is housed in a negative electrode can 54 and the negative electrode 53 and the negative electrode can 54. The positive electrode collector 55 is disposed at the upper end of the negative electrode can 54, the positive electrode 52 is electrically connected to the collector electrode 55, and the upper end 541 of the negative electrode can 54 is connected to the explosion-proof valve. The outer peripheral end of the outer plate 56 and the outer peripheral end of the positive electrode lid 57 are caulked through a packing 58, and the central recess of the explosion-proof valve plate 56 is electrically connected to the positive electrode collector electrode 59.
[0020]
In order to attach the temperature fuse according to the present invention to the battery, one belt-shaped lead conductor and the temperature fuse main body are brought into close contact with the negative electrode can of the battery and the one belt-shaped lead conductor and the negative electrode can. Can be electrically connected to each other, and the other strip-shaped lead conductor can be insulated from the negative electrode can by being separated or interposed by an insulating film and inserted into the battery in series.
[0021]
Further, a temperature fuse is disposed in a space between the explosion-proof valve plate 56 and the positive electrode cover 57 of the lithium ion secondary battery, and between the outer peripheral end of the explosion-proof valve plate 56 and the outer peripheral end of the positive electrode cover 57. Insulating spacer r is interposed, and one strip-shaped lead conductor 2 is held between the outer peripheral end portion of the explosion-proof valve plate 56 and the insulating spacer ring r, and the other strip-shaped lead conductor 2 is attached to the positive electrode lid 57. It can also be held in series by the outer peripheral end and the insulating spacer ring r and incorporated in the battery.
[0022]
5 (a) and 5 (b) (a cross-sectional view of the roll in FIG. 5 (a)) show another embodiment of the temperature fuse according to the present invention.
In FIG. 5, F indicates a frame, and one foil-like electrode f ₁ having one strip-shaped lead conductor 21 on the inner periphery of the annular portion 201 shown in FIG. B) a foil-like electrode f ₂ having the other strip-shaped lead conductor 2 on the inner circumference of the annular portion 200 shown in FIG. And the lead portions 2 and 21 are alternately overlapped by 180 °, and heat bonding or the like can be used for bonding at the interface between the foil electrodes f ₁ and f ₂ and the resin spacer film s. .
[0023]
In FIG. 5, A is a temperature fuse main body arranged in the central space of the frame F, and one end of the belt-like lead conductor 21 is attached to one surface of the base film 11 of a stretched polyethylene terephthalate film. And the other end of the film-like lead conductor 2 is fixed to the other surface of the base film 11, and the front end and the end of the film 11 are fixed. A low melting point soluble alloy piece 3 is connected by welding or the like to the tip portion of one of the strip-shaped lead conductors 21 that is locally exposed, and a flux 4 is applied to the low melting point soluble alloy piece 3. A cover film 12 of a stretched polyethylene terephthalate film is disposed on the flux-coated low melting point soluble alloy piece, and between the resin base film 11 and the resin cover film 12 around the resin cover film 12 and the resin cover. -Film 12 and Square of the strip re - heat between the de conductor 2 - tosylate - le or ultrasonic welding or Le - are sealed by THE irradiation.
[0024]
In order to incorporate this temperature fuse into the battery shown in FIG. 4, it is held between the outer peripheral end portion of the explosion-proof valve plate 56 and the outer peripheral end portion of the positive electrode cover 57 without using the insulating spacer r. valve plate 56 and the frame - electrical contact → foil electrodes f ₁ between the foil electrodes f ₁ of the beam F Li - de conductor 21 → the low melting-point fusible alloy piece 3 → foil electrodes f ₀ of the Li - de conductor Due to the electrical contact between the foil electrode f ₀ of 2 → frame F and the positive electrode lid 57, the temperature fuse can be electrically connected to the battery in series.
[0025]
【Example】
〔Example〕
A stretched polyethylene terephthalate film having a thickness of 200 μm and a heat shrinkage of 1.5% was used. The DSC curve of this stretched polyethylene terephthalate film is as shown in FIG. 7 (a) (however, a differential scanning calorimeter manufactured by Rigaku Corporation was used. Reference sample was α-alumina, atmosphere Gas is N ₂ , heating rate is 10 ° C./min, sampling is 1.0 sec, sample amount is 15.0 mg).
The thin temperature fuse has the configuration shown in FIG. 1, the plane dimensions of the resin base film and the resin cover film are 5 mm × 7 mm, and the strip lead conductor is a nickel strip having a thickness of 100 μm and a width of 3 mm. As the low melting point soluble alloy piece, In 40 wt%, Sn 46 wt%, Cd 14 wt%, cross-sectional area 0.067 mm ² and thickness 48 μm were used, and flux containing rosin as a main component was used. . Sealing and adhesion were heat seals.
[0026]
[Comparative Example]
It was the same as in the Examples, except that a non-stretched polyethylene terephthalate film having a DSC curve thickness of 200 μm shown in FIG. 7B was used for the resin base film and the resin cover film.
[0027]
When the initial tensile strength of the Example and the Comparative Example was measured, the latter was around 70% of the former.
Moreover, when the dimensional stability with respect to a heating was tested about the Example and the comparative example, the difference was not recognized but both were stable.
[0028]
【The invention's effect】
The temperature fuse according to the present invention is an alloy-type temperature fuse having an operating temperature of 80 to 120 ° C., which makes it possible to reduce the thickness of the secondary battery while ensuring good operability. An ultra-thin and ultra-small alloy type temperature fuse can be provided as a temperature fuse for prevention.
[Brief description of the drawings]
FIG. 1 is a view showing an example of a temperature fuse according to the present invention.
FIG. 2 is a drawing showing an example different from the above of the temperature fuse according to the present invention.
FIG. 3 is a drawing showing an example different from the above of the temperature fuse according to the present invention.
FIG. 4 is a view showing an example of a usage state of a temperature fuse according to the present invention.
FIG. 5 is a drawing showing an example different from the above of the temperature fuse according to the present invention.
6 is a view showing a frame used in the temperature fuse shown in FIG. 5. FIG.
7A is a DSC curve of the stretched polyethylene terephthalate film used in the examples of the present invention, and FIG. 7B is a DSC of the unstretched polyethylene terephthalate film used in the comparative example. It is a curve.
[Explanation of symbols]
11 Stretched polyethylene terephthalate film 12 Stretched polyethylene terephthalate film 2 Strip-shaped lead conductor 21 Strip-shaped lead conductor 3 Low melting point soluble alloy piece 4 Flux

Claims

A tip of a pair of strip-shaped lead conductors is fixed on one surface of a resin base film, a low melting point soluble alloy piece is connected between the tips of the strip-shaped lead conductor, and a flux is added to the low melting point soluble alloy piece. The resin cover film is placed on one side of the resin base film, and the gap between the films around the resin film and between the resin cover film and the strip-shaped lead conductor is sealed. The solidus temperature of the melting point soluble alloy piece is 80 to 120 ° C., the liquidus temperature is 80 to 120 ° C., and the DSC curves of both resin films are straight and have no inflection point at the temperature of 80 to 120 ° C. A thin temperature fuse characterized by using a stretched polyethylene terephthalate film.

A pair of strip-shaped lead conductors are fixed to the resin base film by exposing them from the back side to the front side, and a low melting point soluble alloy piece between the tip exposed portions of both strip-shaped lead conductors. And a flux is applied to the low-melting-point soluble alloy piece, and a resin cover film is disposed on the surface of the resin base film, and between the films around both resin films and between the resin cover film and the strip-shaped lead. The low-melting point soluble alloy piece has a solidus temperature of 80 to 120 ° C. and a liquidus temperature of 80 to 120 ° C., and the DSC curve is 80 % on both resin films. A thin temperature fuse characterized by using a stretched polyethylene terephthalate film that is straight and has no inflection point at temperatures up to 120 ° C.

The leading end of one strip-shaped lead conductor is fixed to the resin base film by exposing it from the back side to the front side, and the leading end of the other strip-shaped lead conductor is fixed to the front side of the resin base film. The low melting point soluble alloy piece is connected between the ends of the belt-like lead conductors, the flux is applied to the low melting point soluble alloy piece, and the resin cover film is formed on the surface of the resin base film. And between the films around both resin films and between the resin cover film and the other strip-shaped lead conductor, the solidus temperature of the low melting point soluble alloy piece is 80 to 120 ° C. The liquidus temperature is set to 80 to 120 ° C., and both resin films are characterized by using stretched polyethylene terephthalate films in which the DSC curve is straight and has no inflection point at the temperature of 80 to 120 ° C. Thin temperature fuse.