JP3594644B2

JP3594644B2 - Temperature fuse with resistor

Info

Publication number: JP3594644B2
Application number: JP4527394A
Authority: JP
Inventors: 敏彦川元; 充明植村; 和男有山
Original assignee: Uchihashi Estec Co Ltd
Current assignee: Uchihashi Estec Co Ltd
Priority date: 1994-02-17
Filing date: 1994-02-17
Publication date: 2004-12-02
Anticipated expiration: 2019-12-02
Also published as: JPH07230747A

Description

【０００１】
【産業上の利用分野】
本発明は、基板タイプの合金型温度ヒュ−ズに抵抗体を内蔵させた抵抗体付き温度ヒュ−ズに関するものである。
【０００２】
【従来の技術】
抵抗体付き温度ヒュ−ズにおいては、合金型の温度ヒュ−ズエレメントと抵抗体とを近接配置で一体化し、抵抗体における過電流に基づく発生熱で温度ヒュ−ズエレメントを溶断させ、その過電流を遮断している。
【０００３】
従来、抵抗体付き温度ヒュ−ズとして、ケ−ス型並びに基板型が公知である。
図６の（イ）はケ−ス型抵抗体付き温度ヒュ−ズの断面図を、図６の（ロ）は図６の（イ）におけるロ−ロ断面図をそれぞれ示し、合金型温度ヒュ−ズ１４’、例えば、筒状ケ−スタイプの合金型温度ヒュ−ズ（一直線状のリ−ド線間に温度ヒュ−ズエレメントとしての低融点金属片を橋設し、この低融点金属片にフラックスを塗布し、このフラックス塗布低融点金属片上に筒状ケ−スを挿通し、このケ−スの各端と各リ−ド線との間をエポキシ樹脂等の接着剤で封止したもの）と巻線型抵抗体１７’とを直列に接続し、この接続体をＵ字状に曲げて、一端に開口を有するケ−ス２’（例えば、セラミックスケ−ス）内に収容し、該ケ−ス内に封止材３’、例えば白セメントを充填している。
【０００４】
図７の（イ）は片面タイプの基板型抵抗体付き温度ヒュ−ズの平面説明図を、図７の（ロ）は図７の（イ）におけるロ−ロ断面図をそれぞれ示し、熱伝導性絶縁基板１１’、例えば、セラミックス基板の片面に温度ヒュ−ズ用膜電極１２’，１２’と抵抗用膜電極１６’，１６’とを印刷し、温度ヒュ−ズ用電極１２’，１２’間に低融点金属片１４’を橋設し、この低融点金属片１４’にフラックス１５’を塗布し、また、抵抗用電極１６’，１６’間に膜抵抗体１７’を絶縁基板への焼き付けにより橋設し、各電極１２’（１６’）にリ−ド線１３’（１９’）を接続し、上記絶縁基板１１’の片面上にエポキシ樹脂のような硬化性樹脂層２’を滴下塗装法により被覆している。
【０００５】
図８の（イ）は両面タイプの基板型抵抗体付き温度ヒュ−ズの平面説明図を、図８の（ロ）は同じく底面説明図を、図８の（ハ）は図８の（イ）におけるハ−ハ断面図を、図８の（ニ）は図８の（ロ）におけるニ−ニ断面図をそれぞれ示し、熱伝導性絶縁基板１１’の片面に温度ヒュ−ズ用膜電極１２’，１２’を印刷し、この電極間に低融点金属片１４’を橋設し、この低融点金属片にフラックス１５’を塗布し、また、同絶縁基板１１’の他面に抵抗用膜電極１６’，１６’を印刷し、これらの電極間に膜抵抗体１７’を絶縁基板１１’への焼き付けにより橋設し、各電極１２’（１６’）にリ−ド線１３’（１９’）を接続し、上記絶縁基板１１’の全面にエポキシ樹脂のような硬化性樹脂層３’を浸漬塗装法により被覆している。
【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−ズにおいては、温度ヒュ−ズエレメントと膜抵抗体との相対的位置にずれがあると、抵抗体発生熱の温度ヒュ−ズエレメントへの熱伝達速度にバラツキが生じる。従って、作動特性にバラツキが生じる。
而るに、図６の（イ）並びに図６の（ロ）に示すケ−ス型抵抗体付き温度ヒュ−ズにおいては、抵抗体１７’と温度ヒュ−ズ１４’とを一定の相対的位置のもとでケ−ス内に挿入することは困難であり（その主な原因は、挿入時でのケ−ス内面との摩擦で抵抗体と温度ヒュ−ズとの間にずれが生じる）、作動特性にバラツキが生じ易い。
【０００７】
これに対し、基板型抵抗体付き温度ヒュ−ズにおいては、膜電極、膜抵抗体を印刷法により形成でき、高い印刷精度のために膜電極、膜抵抗体を実質上位置ずれなく形成でき、かつ、温度ヒュ−ズエレメントを電極に高い位置精度で溶接できるから、温度ヒュ−ズエレメントと膜抵抗体との相対的位置を充分に一定にできる。
【０００８】
しかしながら、本発明者等が行った基板型抵抗体付き温度ヒュ−ズについての作動特性の実験結果によれば、図７の（イ）並びに図７の（ロ）に示した片面タイプの基板型抵抗体付き温度ヒュ−ズにおいては、予想通り、作動特性のバラツキを無視できる程度にとどめ得たが、図８の（イ）乃至図８の（ニ）に示した両面タイプの基板型抵抗体付き温度ヒュ−ズにおいては、作動特性のバラツキが予想以上に大であった。
【０００９】
そこで、本発明者等において、その原因を究明したところ、両面タイプの基板型抵抗体付き温度ヒュ−ズにおいては、エポキシ樹脂層を浸漬塗装法により形成しており、エポキシ樹脂浴の硬化に基づくゲル化が経時的に進行し、それに伴い樹脂浴の粘度が変化して浸漬塗布厚が変化し、その結果、抵抗体付き温度ヒュ−ズの絶縁物の体積が変化し、熱容量にバラツキが生じる。而るに、抵抗体付き温度ヒュ−ズにおいて、抵抗体から温度ヒュ−ズエレメントに至る熱伝達路の熱抵抗をＲ、熱容量をＣとすれば、温度ヒュ−ズエレメントの温度上昇速度は、ＲＣにより評価され、その熱容量Ｃが絶縁物の体積の函数となるから、浸漬塗装厚のバラツキが温度ヒュ−ズエレメントが温度上昇速度、従って作動特性のバラツキを招来するのである。
これに対し、片面タイプの基板型抵抗体付き温度ヒュ−ズにおいては、一滴当りのエポキシ樹脂滴下量を計量できるので、Ｃのバラツキを排除できるのである。
【００１０】
本発明の目的は、絶縁基板の片面に温度ヒュ−ズエレメントを、同基板の他面に膜抵抗体をそれぞれ設けてなる抵抗体付き温度ヒュ−ズの作動特性のバラツキを低減乃至は防止することにある。
【００１１】
本発明に係る抵抗体付き温度ヒュ−ズは、熱伝導性絶縁基板の片面に低融点可溶金属片からなるヒュ−ズエレメントを設け、同基板の他面に膜抵抗体を設け、ヒュ−ズエレメント並びに膜抵抗体にそれぞれリ−ド線を接続してなる本体の絶縁基板に、下側を開放したケ−スを、当該基板のヒュ−ズエレメント側をケ−ス内上面側に向けて被設し、ケ−ス内に一定量の硬化性絶縁材を滴下充填したことを特徴とし、膜抵抗体をヒュ−ズエレメントに対し左右に２個設けること、更に、ケ−スの上面中央部に対し同上面の他の部分を絶縁基板に接近させて当該中央部を突出させ、該突出部内にヒュ−ズエレメントを配設することもできる。
【００１２】
以下、図面を参照しつつ本発明の構成について説明する。
図１の（イ）は本発明において使用する抵抗・温度ヒュ−ズ本体の平面図を、図１の（ロ）は同じく底面図を、図１の（ハ）は図１の（イ）におけるハ−ハ断面図を、図１の（ニ）は図１の（ロ）におけるニ−ニ断面図をそれぞれ示している。
図１の（イ）乃至図１の（ニ）において、１１は熱伝導性の絶縁基板であり、セラミックス基板が好適である。１２，１２は絶縁基板１１の片面に設けた一対の膜電極であり、リ−ド線取付部１２１と温度ヒュ−ズエレメント取付部１２２とを備え、縦方向中心線ａ−ａに対し左右対称の膜電極を横方向中心線ｂ−ｂに対し上下対称に配設してある。この膜電極１２は、印刷法、例えば、導電塗料をスクリ−ン印刷し、これを焼き付けたものを使用できる。１３は各膜電極１２に溶接またはろう接したリ−ド線である。１４は膜電極間に溶接により縦方向中央線ａ−ａに沿い橋設した温度ヒュ−ズエレメントであり、丸線または角線（例えば、丸線を扁平化したもの）の低融点可溶合金線材が使用されている。１５は温度ヒュ−ズエレメント１４上に塗布したフラツクスであり、ロジンを主成分とするものが使用されている。
【００１３】
【００１３】
１６，１６、１６，１６は絶縁基板１１の他面に、縦方向中心線ａ−ａに対し左右対称に設けた２対の膜電極であり、一端にリ−ド線取付部１６１を有する帯状膜電極１６２をリ−ド線取付部１６１を絶縁基板１１の左右両端側に位置させるように配設してある。この膜電極１６も上記の印刷法により形成してある。１７は各一対の膜電極１６，１６間に跨り、絶縁基板１１の他面に焼成した膜抵抗体であり、抵抗塗料（抵抗粒子とバインダ−との混合物であり、抵抗粒子には酸化ルテニウム等の酸化金属物の粉末、ニッケルや鉄等の高抵抗金属の粉末を使用でき、バインダ−にはガラスフリツトを使用できる）の印刷・焼き付けにより形成できる。１８は両膜抵抗体１７，１７を覆って設けた保護膜であり、前記ガラスフリツトよりも低融点のガラスフリツトが使用され、膜抵抗体に切り込みを入れる（トリミング）ことによりその抵抗値を調整する際での膜抵抗体のクラック等の発生防止に有効である。１９は膜電極１６に溶接またはろう接により接続したリ−ド線である。
【００１４】
図２の（イ）は本発明に係る抵抗体付き温度ヒュ−ズの一例を示す断面図、図２の（ロ）は図２の（イ）におけるロ−ロ断面図である。
図２の（イ）並びに図２の（ロ）において、１は上記した抵抗体付き温度ヒュ−ズ本体である。２は下側を開放したケ−スであり、上板部２１の周囲に枠縁２２を有し、このケ−ス２を抵抗体付き温度ヒュ−ズ本体１にヒュ−ズエレメント１４側をケ−ス内上面側に向けて被設し、枠縁２２に設けた各Ｖノッチ２２１から各リ−ド線１３，１９を引出してある。
【００１５】
このケ−ス２の枠縁２２の内郭は抵抗体付き温度ヒュ−ズ本体１の絶縁基板１１の外郭を実質上ギャップを残すことなく密嵌状態で被設し得るように設定してあり、当該内郭の縦寸法並びに横寸法を絶縁基板の縦寸法並びに横寸法のそれぞれに対し、１．１倍以下、好ましくは１．０７倍以下としてある。３はケ−ス２内に充填固化した絶縁材であり、ケ−ス開放側を上に向け、粘度が２００００ｃｐｓ〜２０００００ｃｐｓ程度のエポキシ樹脂液を該ケ−ス２内に計量滴下し、常温下で硬化させてある。
【００１６】
上記において、保護層１８を含めた膜抵抗体１７の厚みはリ−ド線１９の直径ｄよりも小であり、フラックス塗布温度ヒュ−ズエレメント１４の高さｈはリ−ド線１３の直径よりも大であり、膜抵抗体１７のリ−ド線１９上の必要絶縁厚みをｔ、絶縁基板の厚みをｅ、膜電極の厚さをｅ’とすれば、ケ−ス２内の高さＴは、
Ｔ≧ｔ＋ｈ＋ｄ＋ｅ＋ｅ’ ▲１▼
に設定される。
【００１７】
上記ケ−スには、電気絶縁物の他、アルミニウム、ステンレス等の金属のプレス成形品の使用も可能であるが、ケ−ス枠縁のＶノッチとリ−ド線との間の絶縁保証の面から、電気絶縁物、特にプラスチック、例えば、エポキシ樹脂、不飽和ポリエステル、ビニルエステル樹脂、フェノ−ル樹脂等の熱硬化性樹脂、ポリ塩化ビニル、塩素化ポリ塩化ビニル、ポリエチレン、ポリプロピレン、アクリロニトリル−ブタジエン−スチレン共重合体、ポリスチレン、ポリカ−ボネ−ト、ポリアミド、ポリフッ化ビニリデン、ポリフェニレンサルファイド、ポリスルホン、ポリエ−テル・エ−テルケトン等の熱可塑性樹脂等の射出成形品を使用することが好ましい。
【００１８】
上記抵抗体付き温度ヒュ−ズの各部の寸法は通常、次ぎのように設定される。
すなわち、基板の縦（温度ヒュ−ズエレメントの方向）寸法：５〜１２ｍｍ、同横寸法：６〜１８ｍｍ、厚み０．５〜１．５ｍｍ、膜電極の厚み：１０〜８０μｍ、膜抵抗体の厚み：１０〜３５μｍ、保護層の厚み：２０〜２００μｍ、温度ヒュ−ズエレメントの直径：０．３〜１．０ｍｍ、温度ヒュ−ズエレメント上の基板からのフラックスの塗布厚み：０．４〜２．０ｍｍ、リ−ド線の直径：０．３〜１．３ｍｍ、膜抵抗体リ−ド線の絶縁材厚み：０．１〜２ｍｍ、ケ−スの内郭：基板の外郭寸法の１．００５〜１．１倍、ケ−スの厚み：０．１〜１．０ｍｍとされ、ケ−ス内の高さＴは上記▲１▼式により設定される。
【００１９】
上記の抵抗・温度ヒュ−ズにおいては、保護すべき電気回路に対し、一方の膜抵抗体を回路のある部分に、他方の膜抵抗体を回路の他部分にそれぞれ挿入接続し、温度ヒュ−ズエレメントを回路の入力端に挿入接続することによって使用され、何れか一方の膜抵抗体に過電流が流れて当該膜抵抗体が発熱すると、その発生熱で温度ヒュ−ズエレメントが溶断され、回路の通電が遮断される。
【００２０】
本発明に係る抵抗体付き温度ヒュ−ズの膜抵抗体の箇数は、回路の如何によっては一箇または三箇とすることもでき、図３の（イ）は膜抵抗体１７が一箇の場合の抵抗・温度ヒュ−ズ本体の平面図を、図３の（ロ）は同じく底面図をそれぞれ示し、抵抗用の一対の膜電極１６，１６を絶縁基板１１の他面の左右両端側に縦方向中心線ａ−ａに対し対称な配置で設け、この膜電極１６，１６に跨って絶縁基板面に膜抵抗体１７を膜成固着し、この膜抵抗体１７を覆って保護膜１８を設けてある。図３の（イ）において、１４は温度ヒュ−ズエレメントを示している。
【００２１】
上記において、ケ−ス２の上面２１と絶縁基板１１との間は、少なくとも、温度ヒュ−ズエレメント１４の直径とフラックス１５の塗布厚みとの総和の間隔で隔離されており、この隔離部分には上記硬化性絶縁材を充填してもよいし、または、未充填の空間のままにしておくこともできる。
【００２２】
請求項２記載の発明においては、図４の（イ）に示すように、ケ−ス２の上面中央部２０に対し同上面の他の部分２０１を絶縁基板１１に接近させて当該中央部を突出させ、該突出部内にフラックス塗布ヒュ−ズエレメント１４を配設することにより、上記した、ケ−ス上面と絶縁基板との間の硬化性絶縁材充填部分または空間部分を極力排除しており、この排除した硬化性絶縁材充填部分または空間部分の分だけ熱容量を小にできる。
【００２３】
このケ−スの寸法は通常、図４の（ロ）に示すように、突出部の内部高さａ＝０．４ｍｍ〜３．０ｍｍ、内部巾ｂ＝１ｍｍ〜１０ｍｍ、他の部分の巾ｃ＝１ｍｍ〜８．５ｍｍ、他の部分の内部高さｄ＝０．９ｍｍ〜３．０ｍｍ、ケ−スの内部長さ＝６．０３〜１９．８ｍｍ、厚み＝０．１ｍｍ〜１．０ｍｍとされる。
また、請求項２記載の発明において使用するケ−ス２の上面は、図５の（イ）や（ロ）に示すような台形、かまぼこ型とすることもできる。
【００２４】
【作用】
抵抗体付き温度ヒュ−ズにおいて、膜抵抗体から温度ヒュ−ズエレメントに至る熱伝達経路の媒質の熱抵抗をＲ、熱容量をＣとすると、膜抵抗体の発生熱による温度ヒュ−ズエレメントの温度上昇速度は、既述した通りＲＣで制せられ、Ｃにバラツキがあれば、温度ヒュ−ズエレメントの温度上昇速度にもバラツキが生じる。
【００２５】
Ｃのバラツキには、第１に絶縁体の体積のバラツキが関与する。而るに、本発明に係る抵抗体付き温度ヒュ−ズにおいては、ケ−ス内に硬化性絶縁材を計量滴下して絶縁体を形成できるから、絶縁体の体積を高精度で一定にでき、更に、ケ−ス、絶縁基板の体積も高精度で一定とでき、絶縁体の体積のバラツキをよく排除でる。
【００２６】
Ｃのバラツキには、第２に外形の定形性が関与する。而るに、ケ−スの外形については、例えば射出成形により定形性をよく保証でき、更に、絶縁基板の膜抵抗体側の面がほぼ平坦であってケ−ス内に充填した絶縁材の表面も、容易に平坦にし得て定形性をよく保証できるから、外形のバラツキもよく排除できる（これに対し、絶縁基板の温度ヒュ−ズエレメント側に、充填絶縁材の表面を配すると、フラックス塗布温度ヒュ−ズエレメントの基板面からの突出高さが大であり、充填絶縁材厚さが薄いと充填絶縁材の表面を平坦にし難く不定形化が余儀なくされ、平坦定形とするには絶縁材の充填厚さを相当に厚くする必要がある。しかし、これでは熱容量が大となって抵抗体付き温度ヒュ−ズの作動速度が遅くなってしまう）。
【００２７】
Ｃのバラツキには、第３に温度ヒュ−ズエレメントと膜抵抗体との相対的位置の精度が関与する。而るに、膜電極、膜抵抗体を印刷法により形成でき、高い印刷精度のために膜電極、膜抵抗体を実質上位置ずれなく形成でき、かつ、温度ヒュ−ズエレメントを膜電極に高い位置精度で溶接できるから、温度ヒュ−ズエレメントと膜抵抗体との相対的位置精度を充分に高精度にできる。
従って、温度ヒュ−ズエレメントの温度上昇速度のバラツキを充分に低減若しくは防止でき、作動特性の一様な抵抗体付き温度ヒュ−ズを量産できる。
更に、請求項２記載の抵抗体付き温度ヒュ−ズにおいては、Ｃを小にできるので、迅速作動が可能となる。
【００２８】
【実施例】
実施例１
図２の（イ）並びに図２の（ロ）に示す構成を用い、抵抗体付き温度ヒュ−ズ本体には図１の（イ）乃至図１の（ニ）に示す構成を使用した。熱伝導性絶縁基板には、厚さ０．６ｍｍ、縦９ｍｍ、横１４ｍｍのセラミックス基板を使用し、全ての膜電極を銀ペ−ストの印刷・焼き付けにより形成し、電極厚みを２５μｍとした。温度ヒュ−ズエレメントには直径０．５ｍｍ、液相温度９６℃の低融点可溶合金線を使用し、フラックス（温度ヒュ−ズエレメントの融点以下の軟化点）の塗布厚みを１．２ｍｍとした。膜抵抗体は、抵抗塗料（酸化ルテニウム粉末とガラスフリットとの混合物）の厚み２０μｍの印刷・焼き付けにより、保護膜は低融点ガラスフリットの厚み８０μｍの焼き付けにそれぞれ膜成し、両膜抵抗体の抵抗値をトリミングにより共に１０００Ωに調整した。リ−ド線には、直径０．６ｍｍの銅線を使用した。ケ−スには、フェノ−ル樹脂の射出成形品で、内郭寸法が縦９．７ｍｍ，横１４．９ｍｍ、内部高さ２．７ｍｍであり、厚みが０．６ｍｍのものを使用し、硬化性絶縁材には、浸漬塗装用のエポキシ樹脂液を使用した。
【００２９】
比較例１
実施例１で使用した抵抗体付き温度ヒュ−ズ本体に、実施例で使用したエポキシ樹脂液を浸漬塗装法により塗布した抵抗体付き温度ヒュ−ズを製作した。
【００３０】
比較例２
実施例１に対し、抵抗体付き温度ヒュ−ズ本体の上下面を逆にし、絶縁基板の温度ヒュ−ズエレメント側に充填絶縁材の表面を配し、かつ、この充填絶縁材の表面を平坦にするように、ケ−ス内部の高さを３ｍｍにしてフラックス塗布温度ヒュ−ズエレメントの上面と充填絶縁材表面との間隔を０．３ｍｍにし、かつ、ケ−ス枠縁のリ−ド線引出用Ｖノッチの深さをリ−ド線の引出し高さに応じて変更した以外、実施例１に同じとした。
【００３１】
実施例並びに比較例で使用したエポキシ樹脂液の常温下でのポットライフは、ほぼ５時間であり、このエポキシ樹脂液のゲル化に起因する抵抗・温度ヒュ−ズの作動特性の変動をチェックするために、実施例１及び比較例２でのエポキシ樹脂液の滴下充填並びに比較例１でのエポキシ樹脂液の浸漬塗布を３０分経過ごとに行い、実施例１及び比較例２については滴下時点の異なるもの各５箇、比較例１については浸漬塗布時点の異なるもの５箇をそれぞれ作成した。
【００３２】
これらの実施例品並びに比較例品のそれぞれにつき、一の各膜抵抗体と温度ヒュ−ズエレメントとをそれぞれ直列に接続し、定格電力（１Ｗ）の９倍の電力を印加し、作動時間（通電開始の後、通電が遮断されるまでの時間）を測定したところ、実施例１では２４秒〜２７秒であったのに対し、比較例１においては、２１秒〜３１秒であり、実施例１では作動時間のバラツキが僅小であるのに対して比較例１においては極めて大であった。
また、比較例２においては、３２秒〜３６秒であり、バラツキは小であったが、作動時間が遅く、作動迅速性（感温性）の点で不合格であった。
【００３３】
実施例２
図４の（イ）に示す構成を用い、抵抗体付き温度ヒュ−ズ本体には、実施例１と同じものを使用した。ケ−スには、フェノ−ル製であり、図４の（ロ）において、突出部の内部高さａ＝１．２ｍｍ、内部巾ｂ＝６．３、他の部分の巾ｃ＝４．３ｍｍ、他の部分の内部高さｄ＝１．５ｍｍ、ケ−スの厚み＝０．６ｍｍとし、ケ−スの縦寸法（温度ヒュ−ズエレメントの方向の長さ）＝９．７ｍｍとした。
他は実施例１と同様とし、エポキシ樹脂液の滴下時点の異なるもの５箇を作成した。
【００３４】
これらの実施例品につき、実施例１と同様に、一の各膜抵抗体と温度ヒュ−ズエレメントとをそれぞれ直列に接続し、定格電力（１Ｗ）の９倍の電力を印加し、作動時間（通電開始の後、通電が遮断されるまでの時間）を測定したところ、２０秒〜２３秒であり、作動時間のバラツキは実施例１と同程度であって僅小であり、また作動時間は実施例１よりも短かった。
【００３５】
【発明の効果】
本発明の抵抗体付き温度ヒュ−ズは上述した通りの構成であり、作動時間のバラツキを低減若しくは防止でき、所定の過電流が流れたのち、バラツキをよく排除して一定時間で通電を遮断できるから、電気回路を高度の信頼性のもとで保護できる。
【図面の簡単な説明】
【図１】図１の（イ）は本発明において使用する抵抗体付き温度ヒュ−ズ本体の一例を示す平面図、図１の（ロ）は同じく底面図、図１の（ハ）は図１の（イ）におけるハ−ハ断面図、図１の（ニ）は図１の（ロ）におけるニ−ニ断面図である。
【図２】図２の（イ）は本発明の実施例を示す断面図、図２の（ロ）は図２の（イ）におけるロ−ロ断面図である。
【図３】図３の（イ）は本発明において使用する抵抗体付き温度ヒュ−ズ本体の別例を示す平面図、図３の（ロ）は同じく底面図である。
【図４】図４の（イ）は請求項２記載の発明の実施例を示す断面図、図４の（ロ）は図４の（イ）におけるケ−スを示す説明図である。
【図５】請求項２記載の発明において使用するケ−スの他の異なる例を示す正面図である。
【図６】図６の（イ）は従来のケ−ス型抵抗体付き温度ヒュ−ズを示す断面図、図６の（ロ）は図６の（イ）におけるロ−ロ断面図である。
【図７】図７の（イ）は従来の片面タイプの基板型抵抗体付き温度ヒュ−ズを示す平面説明図、図７の（ロ）は図７の（イ）におけるロ−ロ断面図である。
【図８】図８の（イ）は従来の両面タイプの基板型抵抗体付き温度ヒュ−ズを示す平面説明図、図８の（ロ）は同じく底面説明図、図８の（ハ）は図８の（イ）におけるハ−ハ断面図、図８の（ニ）は図８の（ロ）におけるニ−ニ断面図である。
【符号の説明】
１１絶縁基板
１２膜電極
１３リ−ド線
１４温度ヒュ−ズエレメント
１５フラックス
１６膜電極
１７膜抵抗体
１９リ−ド線
１抵抗体付き温度ヒュ−ズ本体
２ケ−ス
２０突出部
２１上板部
２２枠縁
３硬化性絶縁材[0001]
[Industrial applications]
The present invention relates to a temperature fuse with a resistor in which a resistor is built in a substrate type alloy type temperature fuse.
[0002]
[Prior art]
In the case of a temperature fuse with a resistor, an alloy-type temperature fuse element and a resistor are integrated in close proximity to each other, and the temperature fuse element is blown by generated heat based on overcurrent in the resistor. The current is interrupted.
[0003]
Conventionally, a case type and a substrate type are known as temperature fuses with resistors.
6A is a cross-sectional view of the temperature fuse with the case-type resistor, and FIG. 6B is a cross-sectional view of the roll in FIG. 14 ', for example, a cylindrical case type alloy type temperature fuse (a low melting point metal piece as a temperature fuse element is bridged between straight lead wires, and this low melting point metal piece is used). And a cylindrical case was inserted through the flux-coated low-melting metal piece, and the space between each end of the case and each lead wire was sealed with an adhesive such as epoxy resin. And a wire-wound resistor 17 'are connected in series, and this connection is bent into a U-shape and accommodated in a case 2' (for example, a ceramic case) having an opening at one end, The case is filled with a sealing material 3 ', for example, white cement.
[0004]
FIG. 7A is a plan view of a single-sided temperature fuse with a substrate-type resistor, and FIG. 7B is a cross-sectional view of FIG. The temperature fuse film electrodes 12 'and 12' and the resistance film electrodes 16 'and 16' are printed on one surface of a conductive insulating substrate 11 ', for example, a ceramic substrate, and the temperature fuse electrodes 12' and 12 'are printed. A low-melting point metal piece 14 'is bridged between them, a flux 15' is applied to the low-melting point metal piece 14 ', and a film resistor 17' is placed between the resistance electrodes 16 'and 16' on an insulating substrate. And a lead wire 13 '(19') is connected to each electrode 12 '(16'), and a curable resin layer 2 'such as an epoxy resin is formed on one surface of the insulating substrate 11'. Is coated by a drop coating method.
[0005]
8A is an explanatory plan view of a double-sided temperature fuse with a substrate-type resistor, FIG. 8B is an explanatory bottom view of the same, and FIG. 8C is FIG. 8 (a) and 8 (b) show a cross-sectional view of FIG. 8 (b). The temperature fuse film electrode 12 is formed on one surface of the heat conductive insulating substrate 11 '. ', 12' are printed, a low melting point metal piece 14 'is bridged between the electrodes, a flux 15' is applied to the low melting point metal piece, and a resistive film is formed on the other surface of the insulating substrate 11 '. Electrodes 16 ', 16' are printed, and a film resistor 17 'is bridged between these electrodes by baking on the insulating substrate 11', and a lead wire 13 '(19) is connected to each electrode 12' (16 '). 2), and the entire surface of the insulating substrate 11 'is covered with a curable resin layer 3' such as an epoxy resin by a dip coating method.
[0006]
[Problems to be solved by the invention]
In the above-mentioned temperature fuse with a resistor, if the relative position between the temperature fuse element and the membrane resistor is shifted, the speed of heat transfer of the heat generated by the resistor to the temperature fuse element varies. . Therefore, the operating characteristics vary.
In the case of the temperature fuse with the case-type resistor shown in FIGS. 6 (a) and 6 (b), the resistor 17 'and the temperature fuse 14' are fixed relative to each other. It is difficult to insert the case into the case (the main cause is that the friction between the case and the inner surface of the case at the time of insertion causes a deviation between the resistor and the temperature fuse. ), The operating characteristics tend to vary.
[0007]
On the other hand, in the temperature fuse with the substrate type resistor, the membrane electrode and the membrane resistor can be formed by a printing method, and the membrane electrode and the membrane resistor can be formed without a substantial displacement for high printing accuracy. In addition, since the temperature fuse element can be welded to the electrode with high positional accuracy, the relative position between the temperature fuse element and the membrane resistor can be kept sufficiently constant.
[0008]
However, according to the experimental results of the operating characteristics of the temperature fuse with the substrate type resistor conducted by the present inventors, the single-sided substrate type shown in FIG. 7A and FIG. In the temperature fuse with the resistor, as expected, the variation in the operating characteristics could be negligible. However, the double-sided board type resistor shown in FIGS. 8 (a) to 8 (d) was used. In the temperature fuse, the variation in the operating characteristics was larger than expected.
[0009]
The inventors of the present invention have investigated the cause, and found that the epoxy resin layer is formed by a dip coating method in a double-sided temperature fuse with a substrate-type resistor, based on the curing of an epoxy resin bath. Gelation progresses with time, and the viscosity of the resin bath changes with the change, so that the dip coating thickness changes. As a result, the volume of the insulator of the temperature fuse with the resistor changes, and the heat capacity varies. . Thus, in a temperature fuse with a resistor, if the thermal resistance of the heat transfer path from the resistor to the temperature fuse element is R, and the heat capacity is C, the temperature rise rate of the temperature fuse element is: Since the heat capacity C is evaluated by RC and the heat capacity C is a function of the volume of the insulator, the variation in the thickness of the dip coating causes the temperature fuse element to increase in temperature and thus the operating characteristics.
On the other hand, in the case of a single-sided temperature fuse with a substrate-type resistor, the amount of epoxy resin dripped per drop can be measured, so that the variation of C can be eliminated.
[0010]
SUMMARY OF THE INVENTION It is an object of the present invention to reduce or prevent variations in operating characteristics of a temperature fuse with a resistor having a temperature fuse element provided on one surface of an insulating substrate and a film resistor provided on the other surface of the substrate. It is in.
[0011]
A temperature fuse with a resistor according to the present invention is provided with a fuse element made of a low-melting-point fusible metal piece on one side of a thermally conductive insulating substrate and a film resistor on the other side of the substrate. A case with its lower side open is placed on the insulating substrate of the main body in which lead wires are connected to the fuse element and the film resistor, respectively, with the fuse element side of the substrate facing the upper surface inside the case. Characterized in that a fixed amount of curable insulating material is dripped and filled in the case, two film resistors are provided on the left and right sides of the fuse element, and furthermore, the upper surface of the case It is also possible to make the other part of the upper surface close to the insulating substrate with respect to the central part so that the central part protrudes, and the fuse element is disposed in the protruding part.
[0012]
Hereinafter, the configuration of the present invention will be described with reference to the drawings.
FIG. 1A is a plan view of the resistance / temperature fuse body used in the present invention, FIG. 1B is a bottom view thereof, and FIG. 1C is FIG. FIG. 1D shows a cross-sectional view taken along line II-II of FIG. 1B.
In FIGS. 1A to 1D, reference numeral 11 denotes a thermally conductive insulating substrate, preferably a ceramic substrate. Reference numerals 12 and 12 denote a pair of membrane electrodes provided on one surface of the insulating substrate 11, which are provided with a lead wire attaching portion 121 and a temperature fuse element attaching portion 122, and are symmetrical with respect to the longitudinal center line aa. Are arranged vertically symmetrically with respect to the horizontal center line bb. This membrane electrode 12 can be used by a printing method, for example, screen printing of a conductive paint and baking it. 13 is a lead wire welded or brazed to each membrane electrode 12. Reference numeral 14 denotes a temperature fuse element bridged between the membrane electrodes along the longitudinal center line aa by welding, and is a low melting point fusible alloy of a round wire or a square wire (for example, a round wire flattened). Wire is used. Reference numeral 15 denotes a flux applied on the temperature fuse element 14, which is mainly composed of rosin.
[0013]
[0013]
Reference numerals 16, 16, 16 and 16 denote two pairs of membrane electrodes provided on the other surface of the insulating substrate 11 symmetrically with respect to the vertical center line aa, and have a strip shape having a lead wire mounting portion 161 at one end. The membrane electrode 162 is disposed such that the lead wire attachment portions 161 are located on both left and right sides of the insulating substrate 11. This membrane electrode 16 is also formed by the above-mentioned printing method. Reference numeral 17 denotes a film resistor straddling between each pair of the membrane electrodes 16 and 16 and baked on the other surface of the insulating substrate 11, and is a resistive paint (a mixture of resistive particles and a binder; (A powder of a metal oxide, a powder of a high-resistance metal such as nickel or iron, and a glass frit as a binder) can be formed by printing and baking. Reference numeral 18 denotes a protective film provided so as to cover both the film resistors 17 and 17. A glass frit having a lower melting point than the glass frit is used. When a resistance is adjusted by cutting (trimming) the film resistor. This is effective in preventing the occurrence of cracks and the like in the film resistor in the above. Reference numeral 19 denotes a lead wire connected to the membrane electrode 16 by welding or brazing.
[0014]
FIG. 2A is a cross-sectional view showing an example of a temperature fuse with a resistor according to the present invention, and FIG. 2B is a cross-sectional view of FIG.
In FIGS. 2A and 2B, reference numeral 1 denotes the above-mentioned temperature fuse body with a resistor. Reference numeral 2 denotes a case whose lower side is opened, which has a frame edge 22 around an upper plate portion 21. The case 2 is connected to the temperature fuse body 1 with a resistor by connecting the fuse element 14 side. The lead wires 13 and 19 are extended from the respective V notches 221 provided on the frame edge 22 so as to extend toward the upper surface side of the case.
[0015]
The inner edge of the frame edge 22 of the case 2 is set so that the outer edge of the insulating substrate 11 of the temperature fuse body 1 with a resistor can be tightly fitted without substantially leaving a gap. The vertical and horizontal dimensions of the inner shell are 1.1 times or less, preferably 1.07 times or less with respect to the vertical and horizontal dimensions of the insulating substrate, respectively. Reference numeral 3 denotes an insulating material filled and solidified in the case 2, and an epoxy resin liquid having a viscosity of about 20,000 cps to 200,000 cps is metered and dropped into the case 2 with the case open side facing upward, and at room temperature. Has been cured.
[0016]
In the above description, the thickness of the film resistor 17 including the protective layer 18 is smaller than the diameter d of the lead wire 19, and the height h of the flux application temperature fuse element 14 is the diameter of the lead wire 13. If the required insulating thickness on the lead wire 19 of the film resistor 17 is t, the thickness of the insulating substrate is e, and the thickness of the membrane electrode is e ', the height in the case 2 is high. T
T ≧ t + h + d + e + e ′ (1)
Is set to
[0017]
As the above case, in addition to an electrical insulator, a press-formed product of a metal such as aluminum or stainless steel can be used, but insulation between the V notch on the edge of the case frame and the lead wire is guaranteed. In view of the above, electric insulators, especially plastics, for example, thermosetting resins such as epoxy resin, unsaturated polyester, vinyl ester resin, phenol resin, polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene, acrylonitrile -It is preferable to use an injection molded product such as a thermoplastic resin such as butadiene-styrene copolymer, polystyrene, polycarbonate, polyamide, polyvinylidene fluoride, polyphenylene sulfide, polysulfone, and polyether-etherketone. .
[0018]
The dimensions of each part of the temperature fuse with a resistor are usually set as follows.
That is, the vertical dimension (direction of the temperature fuse element) of the substrate: 5 to 12 mm, the horizontal dimension: 6 to 18 mm, the thickness of 0.5 to 1.5 mm, the thickness of the membrane electrode: 10 to 80 μm, the thickness of the membrane resistor Thickness: 10 to 35 μm, thickness of protective layer: 20 to 200 μm, diameter of temperature fuse element: 0.3 to 1.0 mm, thickness of applied flux from substrate on temperature fuse element: 0.4 to 2.0 mm, diameter of lead wire: 0.3 to 1.3 mm, thickness of insulating material of film resistor lead wire: 0.1 to 2 mm, inner casing: outer dimension of substrate 0.005 to 1.1 times, the thickness of the case: 0.1 to 1.0 mm, and the height T in the case is set by the above equation (1).
[0019]
In the above-mentioned resistance / temperature fuse, for the electric circuit to be protected, one of the film resistors is inserted and connected to a certain portion of the circuit, and the other is connected to the other portion of the circuit. When an overcurrent flows to one of the membrane resistors and the membrane resistor generates heat, the temperature fuse element is blown by the generated heat, and the temperature fuse element is blown. The circuit is de-energized.
[0020]
The number of the film resistors of the temperature fuse with a resistor according to the present invention may be one or three depending on the circuit. FIG. FIG. 3B is a plan view of the body of the resistance / temperature fuse, and FIG. 3B is a bottom view thereof. A pair of film electrodes 16 for resistance are provided on both left and right sides of the other surface of the insulating substrate 11. A film resistor 17 is provided on the insulating substrate surface across the film electrodes 16, 16 symmetrically with respect to the longitudinal center line aa, and a protective film 18 is covered over the film resistor 17. It is provided. In FIG. 3A, reference numeral 14 denotes a temperature fuse element.
[0021]
In the above, the space between the upper surface 21 of the case 2 and the insulating substrate 11 is separated by at least the total interval of the diameter of the temperature fuse element 14 and the thickness of the applied flux 15, and this separated portion May be filled with the curable insulating material, or may be left unfilled.
[0022]
According to the second aspect of the invention, as shown in FIG. 4A, the other portion 201 of the upper surface of the case 2 is brought closer to the insulating substrate 11 with respect to the central portion 20 of the upper surface of the case 2, and the central portion is By protruding and arranging the flux application fuse element 14 in the protruding portion, the above-mentioned curable insulating material filling portion or space portion between the case upper surface and the insulating substrate is eliminated as much as possible. In addition, the heat capacity can be reduced by the removed portion or space portion filled with the curable insulating material.
[0023]
Usually, the dimensions of this case are, as shown in FIG. 4 (b), the internal height a of the protruding portion a = 0.4 mm to 3.0 mm, the internal width b = 1 mm to 10 mm, and the width c of the other portion. = 1 mm to 8.5 mm, internal height d of other parts = 0.9 mm to 3.0 mm, internal length of the case = 6.03 to 19.8 mm, thickness = 0.1 mm to 1.0 mm. Is done.
Further, the upper surface of the case 2 used in the second aspect of the present invention may be trapezoidal or kamaboko-shaped as shown in FIGS.
[0024]
[Action]
In a temperature fuse with a resistor, when the thermal resistance of the medium in the heat transfer path from the membrane resistor to the temperature fuse element is R, and the heat capacity is C, the temperature fuse element is generated by the heat generated by the membrane resistor. As described above, the temperature rising speed is controlled by RC, and if there is a variation in C, the temperature rising speed of the temperature fuse element also varies.
[0025]
First, the variation in C involves variation in the volume of the insulator. In the temperature fuse with a resistor according to the present invention, the insulator can be formed by metering and dropping the curable insulating material into the case, so that the volume of the insulator can be made constant with high accuracy. In addition, the case and the volume of the insulating substrate can be made constant with high accuracy, and variations in the volume of the insulator can be eliminated.
[0026]
Second, the variation of C involves the formality of the outer shape. The outer shape of the case can be well-defined by, for example, injection molding, and the surface of the insulating substrate on the side of the film resistor is substantially flat, and the surface of the insulating material filled in the case is filled. In addition, since it can be easily flattened and the formability can be well guaranteed, variations in the outer shape can also be eliminated. (In contrast, if the surface of the filled insulating material is arranged on the temperature fuse element side of the insulating substrate, flux application The protruding height of the temperature fuse element from the substrate surface is large, and if the thickness of the filled insulating material is small, it is difficult to flatten the surface of the filled insulating material, and it is inevitable to make it irregular. It is necessary to increase the filling thickness of the resistor considerably, but this will increase the heat capacity and reduce the operating speed of the temperature fuse with the resistor.)
[0027]
Third, the variation in C involves accuracy of the relative position between the temperature fuse element and the film resistor. In addition, the membrane electrode and the membrane resistor can be formed by a printing method, the membrane electrode and the membrane resistor can be formed substantially without displacement for high printing accuracy, and the temperature fuse element can be formed on the membrane electrode with a high temperature. Since the welding can be performed with positional accuracy, the relative positional accuracy between the temperature fuse element and the film resistor can be made sufficiently high.
Therefore, it is possible to sufficiently reduce or prevent the variation of the temperature rising speed of the temperature fuse element, and mass-produce a temperature fuse with a resistor having uniform operating characteristics.
Further, in the temperature fuse with the resistor according to the second aspect, since C can be reduced, quick operation becomes possible.
[0028]
【Example】
Example 1
The configuration shown in FIGS. 2A and 2B was used, and the configuration shown in FIGS. 1A to 1D was used for the temperature fuse body with a resistor. A ceramic substrate having a thickness of 0.6 mm, a length of 9 mm, and a width of 14 mm was used as the heat conductive insulating substrate, and all the membrane electrodes were formed by printing and baking silver paste to make the electrode thickness 25 μm. For the temperature fuse element, a low melting point fusible alloy wire having a diameter of 0.5 mm and a liquid phase temperature of 96 ° C is used, and the applied thickness of the flux (softening point below the melting point of the temperature fuse element) is 1.2 mm. did. The film resistor is formed by printing and baking a resist coating (a mixture of ruthenium oxide powder and glass frit) with a thickness of 20 μm, and the protective film is formed by baking a low melting glass frit with a thickness of 80 μm. The resistance values were both adjusted to 1000Ω by trimming. As the lead wire, a copper wire having a diameter of 0.6 mm was used. The case used is a phenolic resin injection molded product with inner dimensions of 9.7 mm in height, 14.9 mm in width, 2.7 mm in internal height, and 0.6 mm in thickness. An epoxy resin liquid for dip coating was used for the curable insulating material.
[0029]
Comparative Example 1
A temperature fuse having a resistor was manufactured by applying the epoxy resin liquid used in the example to the temperature fuse body having a resistor used in Example 1 by a dip coating method.
[0030]
Comparative Example 2
In contrast to the first embodiment, the upper and lower surfaces of the temperature fuse body with the resistor are reversed, the surface of the filled insulating material is arranged on the temperature fuse element side of the insulating substrate, and the surface of the filled insulating material is flattened. The height of the inside of the case is set to 3 mm, the interval between the upper surface of the fuse application temperature fuse element and the surface of the filled insulating material is set to 0.3 mm, and the lead of the edge of the case frame is set. Example 1 was the same as Example 1 except that the depth of the wire drawing V-notch was changed according to the lead wire drawing height.
[0031]
The pot life at room temperature of the epoxy resin liquid used in Examples and Comparative Examples is about 5 hours, and the fluctuation of the operating characteristics of the resistance / temperature fuse due to the gelation of the epoxy resin liquid is checked. For this purpose, the drop filling of the epoxy resin liquid in Example 1 and Comparative Example 2 and the dip coating of the epoxy resin liquid in Comparative Example 1 were performed every 30 minutes. Five different samples were prepared, and five samples of Comparative Example 1 having different dip coating times were prepared.
[0032]
For each of these examples and comparative examples, one membrane resistor and a temperature fuse element are connected in series, and 9 times the rated power (1 W) is applied, and the operation time ( The time after the start of energization until the energization was interrupted) was measured. In Example 1, the time was 24 seconds to 27 seconds, whereas in Comparative Example 1, the time was 21 seconds to 31 seconds. In Example 1, the variation in the operation time was very small, while in Comparative Example 1, it was extremely large.
In Comparative Example 2, the time was from 32 seconds to 36 seconds, and the variation was small, but the operation time was long and the operation was unsatisfactory in terms of quickness (temperature sensitivity).
[0033]
Example 2
Using the configuration shown in FIG. 4A, the same temperature fuse body as in Example 1 was used as the temperature fuse body with a resistor. The case is made of phenol, and in FIG. 4B, the internal height a of the protruding portion is 1.2 mm, the internal width b is 6.3, and the width c of the other portion is 4. 3 mm, internal height d of other parts = 1.5 mm, case thickness = 0.6 mm, and vertical dimension of the case (length in the direction of the temperature fuse element) = 9.7 mm. .
The other conditions were the same as in Example 1, and five different epoxy resin liquid dropping points were prepared.
[0034]
As in the case of the first embodiment, each one of the film resistors and the temperature fuse element are connected in series with each other, and the power of 9 times the rated power (1 W) is applied to these products, and the operation time is increased. (The time from the start of energization to the interruption of energization) was measured to be 20 to 23 seconds, and the variation of the operation time was almost the same as that in Example 1 and was very small. Was shorter than Example 1.
[0035]
【The invention's effect】
The temperature fuse with a resistor according to the present invention has the same configuration as described above, and can reduce or prevent variations in the operation time. Because of this, the electrical circuit can be protected with a high degree of reliability.
[Brief description of the drawings]
FIG. 1A is a plan view showing an example of a temperature fuse body with a resistor used in the present invention, FIG. 1B is a bottom view thereof, and FIG. 1 (a) is a sectional view taken along the line c-c, and FIG. 1 (d) is a sectional view taken along the line d-b in FIG. 1 (b).
2A is a cross-sectional view showing an embodiment of the present invention, and FIG. 2B is a cross-sectional view of FIG.
FIG. 3A is a plan view showing another example of the temperature fuse body with a resistor used in the present invention, and FIG. 3B is a bottom view of the same.
FIG. 4A is a sectional view showing an embodiment of the invention according to claim 2, and FIG. 4B is an explanatory view showing a case in FIG. 4A.
FIG. 5 is a front view showing another different example of the case used in the invention described in claim 2;
6 (A) is a cross-sectional view showing a conventional temperature fuse with a case-type resistor, and FIG. 6 (B) is a cross-sectional view of FIG. 6 (A). .
7A is an explanatory plan view showing a conventional temperature fuse with a single-sided substrate-type resistor, and FIG. 7B is a cross-sectional view taken along the line B in FIG. 7A. It is.
8 (a) is a plan view showing a conventional double-sided temperature fuse with a substrate type resistor, FIG. 8 (b) is a bottom view, and FIG. 8 (c) is a plan view. FIG. 8A is a cross-sectional view taken along line c-c of FIG. 8, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Insulating substrate 12 Membrane electrode 13 Lead wire 14 Temperature fuse element 15 Flux 16 Membrane electrode 17 Membrane resistor 19 Lead wire 1 Temperature fuse body 2 with resistor 2 Case 20 Projection 21 Upper plate Part 22 frame edge 3 curable insulating material

Claims

A fuse element made of a low melting point fusible metal piece is provided on one side of a thermally conductive insulating substrate, and a film resistor is provided on the other side of the substrate. Lead wires are respectively provided on the fuse element and the film resistor. A case whose lower side is opened is placed on the insulating substrate of the connected main body with the fuse element side of the substrate facing the upper surface side of the case, and a fixed amount of the case is placed in the case. A temperature fuse with a resistor, wherein a curable insulating material is dropped and filled .

2. The temperature fuse with a resistor according to claim 1, wherein two film resistors are provided on the left and right of the fuse element.

3. The resistor according to claim 1, wherein the other portion of the upper surface is brought closer to the insulating substrate with respect to the central portion of the upper surface of the case so that the central portion protrudes, and the fuse element is disposed in the protruding portion. With temperature fuse.