JP2004090037A

JP2004090037A - Resistance welding method, electronic parts, irreversible circuit element and communication device

Info

Publication number: JP2004090037A
Application number: JP2002254931A
Authority: JP
Inventors: Noriyuki Umebayashi; 梅林　憲之
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2002-08-30
Filing date: 2002-08-30
Publication date: 2004-03-25

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistance welding method by which metallic members can stably and surely be welded together in a multipoint projection resistance welding, and to provide electronic parts, an irreversible circuit element and a communication device, . <P>SOLUTION: In the resistance welding, after a gradient raise to 1,800A in 1 m/second, energization is performed for 2 m/second at 1,800A in the initial stage. By flowing such a comparatively large current, concentration of a welding current takes place successively on projections of small contact resistance among a plurality of projections, melting metallic plating layers (Ag and Cu plating layers) at the tip end contact part of the projections and exposing the base metal (Fe plate). Then, the energization is suspended for 50 m/second to cool the projections heated by Joule heat. After that, the welding current in the intermediate stage is rapidly raised and energized for 2 m/second at 1,800A. Further, the welding current is decreased in gradation to 900A in 8 m/second for the period from the intermediate to the last stage of the energization. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、抵抗溶接方法、電子部品、非可逆回路素子および通信装置に関する。
【０００２】
【従来の技術】
従来より、例えば、特開平１１−７６４号公報に記載されているように、複数の突起部で同時に抵抗溶接する方法、いわゆる多点同時プロジェクション抵抗溶接方法が知られている。
【０００３】
【発明が解決しようとする課題】
この多点同時プロジェクション抵抗溶接方法を用いて、例えばＡｇめっき層が表面に形成された母材Ｆｅ同士を接合する場合、母材Ｆｅの抵抗値よりもＡｇめっき層の方が小さく、抵抗溶接途中の抵抗値の変化は、Ａｇめっき層がないものに比較して格段に大きい。溶接電流は抵抗の小さい突起部に集中するため、そこに発熱が集中してそれぞれの箇所の溶接が別個に進行するため、抵抗値にばらつきが生じる。多点同時溶接では、抵抗値が違えば電流にばらつきが生じ、発熱量が異なってしまい、安定した抵抗溶接を実現することが困難であった。
【０００４】
抵抗溶接途中の抵抗値の変化に発熱量を影響されにくくするには、溶接電流を供給する電源を電圧設定制御型にすればよい。電圧設定制御型電源では、途中で抵抗値が変化すれば、電流が反比例するため、発熱量の変化は、一定電流を流す場合に比べ、小さくすることができる。しかし、電圧設定制御型電源では、抵抗溶接機の溶接電極端子と被溶接物間の接触抵抗（溶接電極表面抵抗）を含めた総抵抗値と電流値が反比例するため、溶接電極端子の表面状態（被溶接物との接触抵抗）に溶接が大きく左右される（接触抵抗が大きければ電流が小さくなり溶接が弱くなる）という欠点が存在する。電圧設定制御ではなく電力設定制御としても、制御に電圧のパラメータが含まれているため、溶接電極端子の表面状態に左右されてしまう現象は排除できない。
【０００５】
なお、特開平６−１１４５６３号公報および特開平７−８８６５９号公報には、金属母材より小さい電気抵抗値と金属母材より低い融点とを有した金属被覆層を表面に設けた金属母材同士を抵抗溶接する方法が記載されている。しかしながら、特開平６−１１４５６３号公報および特開平７−８８６５９号公報に記載された抵抗溶接方法では、一箇所づつ個別にしか抵抗溶接を行うことができない。なぜなら、単一電源で複数箇所を同時に抵抗溶接すると、それぞれの箇所の抵抗率の変化を個別に分析できないため、最適な通電電流条件を決定することが困難だからである。特に、特開平７−８８６５９号公報に記載された抵抗溶接方法は、被溶接物に通電される電流を検出して通電可能な状態か否かを判定する方法である。このため、複数の溶接箇所の溶接進行具合が異なった場合に、個別の抵抗値の変化と全体の抵抗値の変化が一致せず、正確な判定を得ることは非常に困難である。
【０００６】
そこで、本発明の目的は、複数の突起部で同時に抵抗溶接する多点同時プロジェクション抵抗溶接において、金属部材同士を安定して確実に抵抗溶接することができる抵抗溶接方法、電子部品、非可逆回路素子および通信装置を提供することにある。
【０００７】
【課題を解決するための手段および作用】
前記目的を達成するため、本発明に係る抵抗溶接方法は、金属被覆層を表面に設けた金属母材同士を、前記金属母材に形成した突起部で溶接する抵抗溶接方法であって、前記金属被覆層が、前記金属母材より小さい電気抵抗値を有するとともに、前記金属母材より低い融点を有し、前記金属母材に形成した複数の突起部で同時に溶接する際に、通電の中期から終期に到る期間の溶接電流を減少させることを特徴とする。
【０００８】
より具体的には、通電の初期の溶接電流を相対的に大きくし、かつ、通電時間を相対的に短くするとともに、通電の中期から終期に到る期間の溶接電流を徐々に減少させて相対的に小さくし、かつ、通電時間を相対的に長くする。
【０００９】
以上の方法により、通電の初期の溶接電流で、複数の突起部のうち、接触抵抗の小さい突起に順次、溶接電流の集中が起こり、突起部の金属めっき被覆層が溶融して金属母材が露出する。次に、通電の中期から後期に到る期間の溶接電流を減少させることにより、それぞれの突起部を流れる溶接電流を小さくして、金属母材の電気抵抗が大きいことによる過度の温度上昇を抑え、溶接過大を抑える。
【００１０】
また、溶接電流を電流設定制御することにより、電流の流し始めの条件、ピーク電流および流し終わりの条件を全て制御することができる。しかも、抵抗溶接機の電極端子と被溶接物との間の接触抵抗が変化しても、溶接電流値を所望の値にすることができ、抵抗溶接に与える影響が小さくなる。従って、抵抗溶接がさらに安定となる。
【００１１】
さらに、通電期間の途中に、通電休止期間を設けることにより、ジュール熱で熱くなった突起部が一時冷却され、この後に流される溶接電流が大き過ぎても、溶接過大によるスプラッシュが発生しにくくなる。
【００１２】
また、本発明に係る電子部品や非可逆回路素子は、前述の特徴を有する抵抗溶接方法を用いることにより、金属部材同士を安定して確実に抵抗溶接することができ、所定の接合強度を有し、接合強度のばらつきの小さい金属部品や金属ケースが得られる。
【００１３】
また、本発明に係る通信装置は、前述の特徴を有する電子部品や非可逆回路素子を備えることにより、低コストで高い信頼性が得られる。
【００１４】
【発明の実施の形態】
以下に、本発明に係る抵抗溶接方法、電子部品、非可逆回路素子及び通信装置の実施の形態について添付の図面を参照して説明する。
【００１５】
［第１実施形態、図１〜図８］
本発明に係る非可逆回路素子の一実施形態の構成を示す分解斜視図を図１に示す。図２（Ａ）は上側ケースの側面図、図２（Ｂ）はその底面図である。図３は上側ケースと下側ケースの抵抗溶接方法を示す概略断面図であり、両ケースのみを図示している。該非可逆回路素子１は、集中定数型アイソレータである。
【００１６】
図１に示すように、アイソレータ１は、概略、磁性体金属からなる下側ケース４と、樹脂ケース３と、中心電極組立体１３と、磁性体金属からなる上側ケース８と、永久磁石９と、抵抗素子Ｒと、整合用コンデンサ素子Ｃ１〜Ｃ３等を備えている。
【００１７】
上側ケース８および下側ケース４は軟鉄等の磁性体金属からなる所定厚みの金属板をプレス加工等により打ち抜きし、曲げ加工した後、表面にＡｕ，Ａｇ，Ｃｕ，Ｎｉ等をめっきしてなるものである。上側ケース８と下側ケース４とからなる金属ケースは、磁気回路を形成するとともに他の構成部材を収納保持する外部ケースとしての機能も有している。
【００１８】
このアイソレータ１は縦横約７．０ｍｍ、高さ約２．０ｍｍの外径寸法であり、上側ケース８および下側ケース４は、金属母材として厚みが１６０μｍのＦｅ板を用い、その表面に挿入損失減少の観点から１次（下地）めっきとして厚みが３μｍのＣｕめっき層を形成し、２次めっきとして厚みが３μｍのＡｇめっき層を形成している。つまり、ケース４，８は、金属母材より小さい電気抵抗値と金属母材より低い融点とを有した金属被覆層（Ａｇめっき層とＣｕめっき層）を表面に設けた金属母材（Ｆｅ板）からなる。表１にＡｇ，Ｃｕ，Ｆｅの諸特性を記載する。
【００１９】
【表１】

【００２０】
上側ケース８は、平面視略矩形状の上壁８ａと対向する２対（四つ）の側壁８ｂ，８ｂ，８ｃ，８ｃを有している。対向する二つの側壁８ｂの外面は下側ケース４の両側壁４ｂと接合される面であり、それぞれの側壁８ｂには略半球状の突起部３１が２箇所に形成されている。各突起部３１は下側ケース４の側壁４ｂ側に突出するようにプレス加工により一体に設けられている。各突起部３１は、例えば接合面での直径２５μｍ、接合面から先端までの高さ５０μｍの略半球状に形成されている。下側ケース４は、底壁４ａと１対の側壁４ｂ，４ｂを有している。それぞれの側壁４ｂの内面は上側ケース８の側壁８ｂとの接合面となる。
【００２１】
上側ケース８の両側壁８ｂ間の寸法と下側ケース４の両側壁４ｂ間の寸法は、上側ケース８と下側ケース４とを嵌合した状態で、上側ケース８の各突起部３１の先端部がそれぞれ下側ケース４の二つの側壁４ｂに押圧接触するように形成されている。そして、本第１実施形態のアイソレータ１は、後述するように、上側ケース８と下側ケース４が、上側ケース８の両側壁８ｂの突起部３１にて下側ケース４の両側壁４ｂに抵抗溶接により接合されている。
【００２２】
樹脂ケース３は、底部３ａと四つの側部３ｂを有している。この底部３ａの中央部には矩形状の窓部３ｃが形成されており、窓部３ｃの周縁にはそれぞれ後述する整合用コンデンサ素子Ｃ１〜Ｃ３や抵抗素子Ｒがそれぞれ収納される収納部３ｄが形成されている。樹脂ケース３には、入力端子１４、出力端子１５及びアース端子１６がインサートモールドされている。端子１４〜１６は、それぞれ一端が樹脂ケース３の外側面に露出し、他端が樹脂ケース３の底部３ａに露出して入力引出電極１４ａ、出力引出電極１５ａ及びアース引出電極１６ａとされている。端子１４〜１６は、それぞれ樹脂ケース３の対向する外側面から外方向へ導出している。
【００２３】
整合用コンデンサ素子Ｃ１〜Ｃ３は、誘電体セラミック基板の上面に位置するホット側端子電極と、下面に位置するコールド側（アース側）端子電極を有している。
【００２４】
中心電極組立体１３は、矩形状のマイクロ波フェライト２０の上面に中心電極２１〜２３を略１２０度ごとに交差するように配置している。これら中心電極２１〜２３は、各々の一端側のポート部Ｐ１〜Ｐ３を水平に導出するとともに、他端側の中心電極２１〜２３の共通のアース電極２５をフェライト２０の下面に当接させている。アース電極２５は、フェライト２０の下面を略覆っている。
【００２５】
ここで、中心電極２１〜２３及びアース電極２５は、金属薄板を打ち抜き加工又はエッチング加工することによって形成されたものである。
【００２６】
以上の構成部品は、以下のようにして組み立てられる。下側ケース４上に樹脂ケース３を配置する。このとき、窓部３ｃには下側ケース４の底壁４ａが露出し、下側ケース４とアース端子１６は電気的に接続する。樹脂ケース３内に抵抗素子Ｒや整合用コンデンサ素子Ｃ１〜Ｃ３や中心電極組立体１３等を収容する。
【００２７】
中心電極組立体１３は、フェライト２０の裏面に形成されたアース電極２５が、樹脂ケース３の窓部３ｃを通して、下側ケース４の底壁４ａにはんだ付け等の方法により接続され、接地される。
【００２８】
整合用コンデンサ素子Ｃ１〜Ｃ３は、ホット側コンデンサ電極がポート部Ｐ１〜Ｐ３に電気的に接続され、コールド側コンデンサ電極が樹脂ケース３の内側面に露出しているアース端子１６のアース引出電極１６ａにそれぞれ電気的に接続される。ポート部Ｐ１は入力引出電極１４ａに接続され、ポート部Ｐ２は出力引出電極１５ａに接続される。抵抗素子Ｒの一方の端子電極は、ポート部Ｐ３を介して整合用コンデンサ素子Ｃ３のホット側コンデンサ電極に接続され、他方の端子電極はアース端子１６のアース引出電極１６ａに接続される。つまり、整合用コンデンサ素子Ｃ３と抵抗素子Ｒとは、中心電極組立体１３のポート部Ｐ３とアース端子１６との間に電気的に並列に接続される（図８参照）。
【００２９】
さらに、上側ケース８が下側ケース４に嵌合される。上側ケース８の上壁８ａと中心電極組立体１３の間には永久磁石９が配置されており、この永久磁石９により中心電極組立体１３に直流磁界を印加するようになっている。この組み立ての過程において、両ケース４，８の接合部を除く、他の構成部材同士の接続部には、はんだペーストが塗布され、上側ケース８を下側ケース４に嵌合させた状態で、構成部品同士をはんだ付けする。
【００３０】
次に、図３に示すように、抵抗溶接機の一方の電極端子６１を上側ケース８の上壁８ａに、他方の電極端子６２を下側ケース４の底壁４ａに押し当てる。上側ケース８と下側ケース４を電極端子６１，６２で加圧した状態で溶接電流を流し、上側ケース８の突起部３１を溶融させて、この突起部３１の部分で上側ケース８と下側ケース４とを抵抗溶接により接合する。
【００３１】
さらに、本第１実施形態では、下側ケース４の両側壁４ｂを加圧治具６３により、矢印Ｐで示す方向に加圧している。これにより、各突起部３１での接触抵抗をさらに安定させることができ、より安定で確実な溶接を行うことができる。また、この場合、溶接時に各突起部３１がつぶれ、溶接後の突起部３１の高さを略０ｍｍとすることもでき、外形寸法を抑制するとともに、両ケース４，８の接合面間の隙間が小さくなり、両ケース４，８間の磁気抵抗を小さくでき、電気特性がさらに向上する。なお、左右の両加圧治具６３を下側ケース４に当接する抵抗溶接機の電極端子としてもよい。すなわち、６３と６２は両方を電極端子としてもよく、いずれか一方を電極端子としてもよい。
【００３２】
抵抗溶接機から供給される溶接電流は、単一の電流設定制御型電源から供給される。この電流設定制御型電源は、インバータ式電源で、電流の流し始めの条件、ピーク電流、流し終わりの条件を全て制御することができる。より具体的には、溶接電流の変化を検出し、その検出データをフィードバックして印加電圧を可変して所望の溶接電流を設定する。この電流設定制御型電源を用いれば、抵抗溶接機の電極端子６１，６２と被溶接物である上側ケース８との間の接触抵抗が変化しても、溶接電流値を所望の値にすることができる。従って、抵抗溶接に与える影響を小さくすることができ、さらに安定した抵抗溶接が可能となる。
【００３３】
溶接電流は、図４に示すように、初期段階では、１ｍ秒間で１８００Ａまで傾斜上昇された後、１８００Ａで２ｍ秒間通電される。このような比較的大電流を流すのは、表１に示すように、ＡｇやＣｕの熱伝導率がＦｅの５倍程度あり、小電流では金属めっき被覆層（Ａｇめっき層およびＣｕめっき層）で発生した熱が逃げてしまい、効果的に金属めっき被覆層を融かすことができないからである。
【００３４】
これにより、上側ケース８の接合面に形成された４個の突起部３１の中で、抵抗の小さい突起部３１に溶接電流が集中する。表１に示すようにＡｇやＣｕはＦｅよりも融点が低いため、この突起部３１の先端接触部の金属めっき被覆層（Ａｇめっき層およびＣｕめっき層）がジュール熱で溶融する。そして突起部３１の表面に上側ケース８の金属母材（Ｆｅ板）が露出した時点で、表１に示すようにＦｅの抵抗値はＡｇやＣｕの６倍と大きいため接触抵抗値は急上昇する。このため、この突起部３１に流れる溶接電流は小さくなり、金属めっき被覆層が残っている他の突起部３１の中で、次に抵抗の小さい突起部３１に溶接電流が集中する。こうして、４個の突起部３１に、順次、溶接電流の集中が起こり、突起部３１の先端接触部の金属めっき被覆層が溶融して金属母材（Ｆｅ板）が露出する。
【００３５】
この後、図４に示すように、通電を５０ｍ秒間休止し、ジュール熱で熱くなった４個の突起部３１を冷却する。このような冷却期間を設けることにより、中期段階での溶接電流の値が大き過ぎても、溶接過大によるスプラッシュ発生を防止することができる。
【００３６】
次に、中期段階での溶接電流は急峻に立ち上げられ、１８００Ａで２ｍ秒間通電される。初期段階で金属めっき被覆層が溶融しなかった突起部３１がたとえあったとしても、この大きな溶接電流により、全ての突起部３１の金属めっき被覆層が溶融し、安定かつ確実な溶接が可能となる。
【００３７】
こうして、全ての突起部３１の表面に金属母材（Ｆｅ板）が露出し、抵抗溶接が開始される。金属母材（Ｆｅ板）の抵抗値はＡｇやＣｕよりも大きいため、ジュール熱によるそれぞれの突起部３１での発熱量は極めて大きい。従って、溶接電流を１８００Ａにしたままであると、通電電流量が過大となり、突起部３１が発熱し過ぎて、最悪の場合には突起部３１が溶断してしまうおそれがある。
【００３８】
そこで、溶接電流を、通電の中期から後期に到る期間、８ｍ秒間で９００Ａまで傾斜減少させる。これにより、それぞれの突起部３１を流れる溶接電流が徐々に小さくなり、過度の温度上昇を抑えることができる。
【００３９】
このように、全ての突起部３１の表面に金属母材（Ｆｅ板）を露出させた後、突起部３１での過度の温度上昇を防止するために時間の経過に従い電流を減少させて各突起部３１での溶接を行うことにより、両ケース４，８は突起部３１で安定かつ確実に溶接され、接合（溶接）強度のばらつきも小さなものとなる。
【００４０】
また、本第１実施形態では、上側ケース８の接合面となる側壁８ｂと下側ケース４の接合面となる側壁４ｂは突起部３１のみで接触するようにしているので、両ケース４，８の接触抵抗は安定する。さらに、溶接される箇所（接合点）が突起部３１の箇所に限定されるので、金属ケースの電気・磁気回路のばらつきが小さくなる。したがって、電気特性のばらつきが小さくなり、電気特性が向上する。
【００４１】
なお、溶接電流条件は任意であって、例えば図５および図６に示すように、通電休止期間を有さないものであってもよい。図５に記載されている溶接電流は、初期で急峻に立ち上げられ、１８００Ａで２ｍ秒間通電された後、中期から後期に到る期間（８ｍ秒間）で９００Ａまで傾斜減少されている。また、図６に記載されている溶接電流は、１ｍ秒間で１８００Ａまで傾斜上昇された後、１０ｍ秒間で０Ａまで傾斜減少されている。
【００４２】
こうして、図７に示すようなアイソレータ１が得られる。図８は、アイソレータ１の電気等価回路図である。
【００４３】
［第２実施形態、図９］
第２実施形態は、本発明に係る通信装置として、携帯電話を例にして説明する。
【００４４】
図９は携帯電話１２０のＲＦ部分の電気回路ブロック図である。図９において、１２２はアンテナ素子、１２３はデュプレクサ、１３１は送信側アイソレータ、１３２は送信側増幅器、１３３は送信側段間用帯域通過フィルタ、１３４は送信側ミキサ、１３５は受信側増幅器、１３６は受信側段間用帯域通過フィルタ、１３７は受信側ミキサ、１３８は電圧制御発振器（ＶＣＯ），１３９はローカル用帯域通過フィルタである。
【００４５】
ここに、送信側アイソレータ１３１として、前記第１実施形態のアイソレータ１を使用することができる。このアイソレータ１を実装することにより、低コストで優れた電気特性を有する携帯電話を実現することができる。
【００４６】
［他の実施形態］
本発明は、前記実施形態に限定されるものではなく、本発明の要旨の範囲内で種々の構成に変更することができる。例えば、前記第１実施形態ではアイソレータに適用したが、本発明は、勿論サーキュレータにも適用できるとともに、複数の金属部材を接合して構成した金属部品を備えた他の電子部品にも適用できる。また、それぞれの中心電極２１〜２３の交差角は、１１０〜１４０度の範囲であればよい。さらに、金属ケースは三つ以上に分割されていてもよい。また、フェライト２０は直方体形状に限定されるものではなく、円板や六角形等の他の形状でもよい。
【００４７】
また、前記実施形態では、上側ケース８の接合面である両側壁８ｂにそれぞれ突起部３１を２個形成したが、一つの接合面に形成される突起部の数は１個以上形成されておればよい。
【００４８】
また、前記実施形態では、上側ケース８の接合面に溶接用の突起部３１を設けたもので説明したが、突起部３１を下側ケース４の接合面に設けるようにしてもよい。しかし、突起部３１での安定な接触を得るために、またケースのコストを低減するために、突起部３１はいずれか一方のケースの接合面に設けられる。
【００４９】
また、突起部の形状も前記実施形態のものに限るものではなく、略円筒状、略角筒状、略円錐状、略角錘状であってもよく、突起部は金属部材の接合面の溶接したい箇所にプレス加工等により所定の形状で形成される。
【００５０】
【発明の効果】
以上の説明から明らかなように、本発明によれば、金属母材より小さい電気抵抗値を有するとともに金属母材より低い融点を有した金属被覆層を表面に設けた金属母材同士を、単一電源回路で同時に複数の突起部を抵抗溶接する際に、通電の中期から終期に到る期間の通電電流を減少させることにより、金属部材同士を安定して確実に抵抗溶接することができる。従って、所定の接合強度を有し、接合強度のばらつきの小さい金属部品や金属ケースを得ることができ、信頼性が高く低コストの電子部品や非可逆回路素子や通信装置を得ることができる。
【００５１】
また、多点同時プロジェクション抵抗溶接を安定して行うことが可能となるため、一点一点を別々に抵抗溶接する場合に比較して、組立工数の削減、生産性の向上を図ることができる。
【図面の簡単な説明】
【図１】本発明に係る非可逆回路素子の一実施形態を示す分解斜視図。
【図２】（Ａ）は図１に示した上側ケースの側面図であり、（Ｂ）は上側ケースの平面図。
【図３】上側ケースと下側ケースの抵抗溶接方法を示す概略断面図。
【図４】通電電流条件の一例を示すグラフ。
【図５】通電電流条件の別の例を示すグラフ。
【図６】通電電流条件のさらに別の例を示すグラフ。
【図７】図１に示した非可逆回路素子の外観斜視図。
【図８】図７に示した非可逆回路素子の電気等価回路図。
【図９】本発明に係る通信装置の一実施形態を示すブロック図。
【符号の説明】
１…アイソレータ（非可逆回路素子）
４…下側ケース
８…上側ケース
９…永久磁石
１３…中心電極組立体
２０…マイクロ波フェライト
２１〜２３…中心電極
１２０…携帯電話（通信装置）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a resistance welding method, an electronic component, a non-reciprocal circuit device, and a communication device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as described in, for example, JP-A-11-764, a method of simultaneously performing resistance welding at a plurality of projections, that is, a so-called multipoint simultaneous projection resistance welding method has been known.
[0003]
[Problems to be solved by the invention]
For example, when joining base metals Fe having an Ag plating layer formed on the surface thereof by using the multi-point simultaneous projection resistance welding method, the resistance of the Ag plating layer is smaller than the resistance value of the base metal Fe. Is much larger than that without the Ag plating layer. Since the welding current is concentrated on the protrusion having a small resistance, heat is concentrated on the projection and welding at each portion proceeds separately, so that the resistance value varies. In simultaneous multi-point welding, if the resistance value differs, the current varies, and the calorific value varies, making it difficult to realize stable resistance welding.
[0004]
In order to make the amount of generated heat less affected by a change in resistance value during resistance welding, the power supply for supplying the welding current may be a voltage setting control type. In the voltage setting control type power supply, if the resistance value changes in the middle, the current is inversely proportional, so that the change in the amount of generated heat can be made smaller than when a constant current flows. However, in a voltage setting control type power supply, the total resistance value including the contact resistance (welding electrode surface resistance) between the welding electrode terminal of the resistance welding machine and the workpiece is inversely proportional to the current value. There is a drawback that welding is greatly affected by (contact resistance with the workpiece) (the larger the contact resistance, the smaller the current and the weaker the welding). Even when the power setting control is performed instead of the voltage setting control, since the control includes a voltage parameter, a phenomenon that is dependent on the surface state of the welding electrode terminal cannot be excluded.
[0005]
JP-A-6-114563 and JP-A-7-88659 disclose a metal base material provided on its surface with a metal coating layer having an electric resistance smaller than the metal base and a melting point lower than the metal base. A method of resistance welding the two is described. However, according to the resistance welding methods described in JP-A-6-114563 and JP-A-7-88659, resistance welding can be performed only one by one. This is because, when resistance welding is performed simultaneously at a plurality of locations with a single power supply, the change in resistivity at each location cannot be individually analyzed, so that it is difficult to determine an optimal energizing current condition. In particular, the resistance welding method described in Japanese Patent Application Laid-Open No. 7-88659 is a method of detecting a current supplied to an object to be welded and determining whether or not the current can be supplied. For this reason, when the welding progresses at a plurality of welding locations are different, the change in the individual resistance does not match the change in the overall resistance, and it is very difficult to obtain an accurate determination.
[0006]
Accordingly, an object of the present invention is to provide a resistance welding method, an electronic component, and a non-reciprocal circuit that can stably and reliably perform resistance welding between metal members in multipoint simultaneous projection resistance welding in which resistance welding is performed simultaneously on a plurality of protrusions. An element and a communication device are provided.
[0007]
Means and action for solving the problem
In order to achieve the above object, a resistance welding method according to the present invention is a resistance welding method in which metal base materials provided with a metal coating layer on the surface are welded to each other at a protrusion formed on the metal base material, The metal coating layer has an electric resistance value smaller than that of the metal base material, has a lower melting point than the metal base material, and when welding is simultaneously performed at a plurality of protrusions formed on the metal base material, the middle It is characterized in that the welding current in the period from to the end is reduced.
[0008]
More specifically, the welding current in the initial stage of energization is relatively large, and the energizing time is relatively short, and the welding current in the period from the middle stage to the end of energization is gradually reduced. And a relatively long energization time.
[0009]
According to the above method, the welding current is concentrated on the projection having the smaller contact resistance among the plurality of projections in the initial welding current at the time of energization, and the metal plating coating layer of the projections is melted and the metal base material is formed. Exposed. Next, by reducing the welding current in the middle to late stages of energization, the welding current flowing through each projection is reduced, and the excessive temperature rise due to the large electrical resistance of the metal base material is suppressed. , Suppress excessive welding.
[0010]
In addition, by controlling the welding current by current setting, it is possible to control all of the conditions at the beginning of the current, the peak current, and the end of the current. Moreover, even if the contact resistance between the electrode terminal of the resistance welding machine and the workpiece changes, the welding current value can be set to a desired value, and the effect on resistance welding is reduced. Therefore, resistance welding becomes more stable.
[0011]
Furthermore, by providing an energization suspension period in the middle of the energization period, the protrusion heated by Joule heat is temporarily cooled, and even if the welding current flowing thereafter is too large, splash due to excessive welding hardly occurs. .
[0012]
In addition, the electronic component and the non-reciprocal circuit device according to the present invention can stably and reliably perform resistance welding between metal members by using the resistance welding method having the above-described features, and have a predetermined bonding strength. As a result, a metal part or a metal case having a small variation in bonding strength can be obtained.
[0013]
In addition, the communication device according to the present invention includes the electronic component and the non-reciprocal circuit device having the above-described features, so that high reliability can be obtained at low cost.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a resistance welding method, an electronic component, a non-reciprocal circuit device, and a communication device according to the present invention will be described with reference to the accompanying drawings.
[0015]
[First Embodiment, FIGS. 1 to 8]
FIG. 1 is an exploded perspective view showing the configuration of one embodiment of the non-reciprocal circuit device according to the present invention. FIG. 2A is a side view of the upper case, and FIG. 2B is a bottom view thereof. FIG. 3 is a schematic cross-sectional view showing a resistance welding method for the upper case and the lower case, and shows only both cases. The non-reciprocal circuit device 1 is a lumped constant type isolator.
[0016]
As shown in FIG. 1, the isolator 1 generally includes a lower case 4 made of a magnetic metal, a resin case 3, a center electrode assembly 13, an upper case 8 made of a magnetic metal, and a permanent magnet 9. , A resistance element R, and matching capacitor elements C1 to C3.
[0017]
The upper case 8 and the lower case 4 are formed by punching a metal plate having a predetermined thickness made of a magnetic metal such as soft iron by pressing or the like, bending the metal plate, and plating the surfaces with Au, Ag, Cu, Ni, or the like. Things. The metal case including the upper case 8 and the lower case 4 forms a magnetic circuit and also has a function as an external case for storing and holding other components.
[0018]
The isolator 1 has an outer diameter of about 7.0 mm in length and width and a height of about 2.0 mm. The upper case 8 and the lower case 4 use a 160 μm-thick Fe plate as a metal base material and are inserted into the surface thereof. From the viewpoint of loss reduction, a Cu plating layer having a thickness of 3 μm is formed as primary (base) plating, and an Ag plating layer having a thickness of 3 μm is formed as secondary plating. That is, the

cases

4 and 8 are made of a metal base material (Fe plate) provided with a metal coating layer (Ag plating layer and Cu plating layer) having an electric resistance value smaller than that of the metal base material and a melting point lower than that of the metal base material. ). Table 1 describes various properties of Ag, Cu, and Fe.
[0019]
[Table 1]

[0020]
The upper case 8 has two pairs (four) of

side walls

8b, 8b, 8c, 8c opposed to the upper wall 8a having a substantially rectangular shape in plan view. The outer surfaces of the two opposing side walls 8b are surfaces that are joined to the side walls 4b of the lower case 4, and each side wall 8b has substantially hemispherical projections 31 formed at two places. Each projection 31 is provided integrally by press working so as to protrude toward the side wall 4 b of the lower case 4. Each projection 31 is formed in a substantially hemispherical shape with a diameter of 25 μm at the joint surface and a height of 50 μm from the joint surface to the tip, for example. The lower case 4 has a bottom wall 4a and a pair of

side walls

4b, 4b. The inner surface of each side wall 4b serves as a joint surface with the side wall 8b of the upper case 8.
[0021]
The dimension between the side walls 8b of the upper case 8 and the dimension between the side walls 4b of the lower case 4 are determined by the tip of each protrusion 31 of the upper case 8 in a state where the upper case 8 and the lower case 4 are fitted. The portions are formed so as to press and contact the two side walls 4b of the lower case 4 respectively. In the isolator 1 according to the first embodiment, as described later, the upper case 8 and the lower case 4 are connected to the side walls 4b of the lower case 4 by the protrusions 31 of the side walls 8b of the upper case 8. Joined by welding.
[0022]
The resin case 3 has a bottom 3a and four sides 3b. A rectangular window 3c is formed at the center of the bottom 3a, and a housing 3d for accommodating matching capacitor elements C1 to C3 and a resistance element R, which will be described later, is provided on the periphery of the window 3c. Is formed. The input terminal 14, the output terminal 15, and the ground terminal 16 are insert-molded in the resin case 3. One end of each of the terminals 14 to 16 is exposed to the outer surface of the resin case 3, and the other end is exposed to the bottom 3 a of the resin case 3 to be an input lead electrode 14 a, an output lead electrode 15 a, and a ground lead electrode 16 a. . The terminals 14 to 16 respectively extend outward from the opposing outer surfaces of the resin case 3.
[0023]
Each of the matching capacitor elements C1 to C3 has a hot-side terminal electrode located on the upper surface of the dielectric ceramic substrate and a cold-side (earth-side) terminal electrode located on the lower surface.
[0024]
The center electrode assembly 13 is arranged on the upper surface of the rectangular-shaped microwave ferrite 20 so that the center electrodes 21 to 23 intersect at approximately 120 degrees. The center electrodes 21 to 23 lead out the port portions P1 to P3 on one end side horizontally, and make the common ground electrode 25 of the center electrodes 21 to 23 on the other end side contact the lower surface of the ferrite 20. I have. The ground electrode 25 substantially covers the lower surface of the ferrite 20.
[0025]
Here, the center electrodes 21 to 23 and the ground electrode 25 are formed by punching or etching a thin metal plate.
[0026]
The above components are assembled as follows. The resin case 3 is arranged on the lower case 4. At this time, the bottom wall 4a of the lower case 4 is exposed to the window 3c, and the lower case 4 and the ground terminal 16 are electrically connected. The resistance element R, the matching capacitor elements C1 to C3, the center electrode assembly 13, and the like are housed in the resin case 3.
[0027]
In the center electrode assembly 13, the ground electrode 25 formed on the back surface of the ferrite 20 is connected to the bottom wall 4a of the lower case 4 through a window 3c of the resin case 3 by soldering or the like, and is grounded. .
[0028]
The matching capacitor elements C1 to C3 have the hot side capacitor electrodes electrically connected to the port portions P1 to P3, and the cold side capacitor electrodes are exposed on the inner side surface of the resin case 3 to the ground lead electrode 16a of the ground terminal 16. Are electrically connected to each other. The port P1 is connected to the input extraction electrode 14a, and the port P2 is connected to the output extraction electrode 15a. One terminal electrode of the resistance element R is connected to the hot-side capacitor electrode of the matching capacitor element C3 via the port portion P3, and the other terminal electrode is connected to the ground lead electrode 16a of the ground terminal 16. That is, the matching capacitor element C3 and the resistance element R are electrically connected in parallel between the port P3 of the center electrode assembly 13 and the ground terminal 16 (see FIG. 8).
[0029]
Further, the upper case 8 is fitted to the lower case 4. A permanent magnet 9 is disposed between the upper wall 8 a of the upper case 8 and the center electrode assembly 13, and a DC magnetic field is applied to the center electrode assembly 13 by the permanent magnet 9. In this assembling process, the solder paste is applied to the connection between the other components except for the joint between the two

cases

4 and 8, and the upper case 8 is fitted to the lower case 4, Solder the components together.
[0030]
Next, as shown in FIG. 3, one electrode terminal 61 of the resistance welding machine is pressed against the upper wall 8a of the upper case 8, and the other electrode terminal 62 is pressed against the bottom wall 4a of the lower case 4. A welding current is applied in a state where the upper case 8 and the lower case 4 are pressed by the

electrode terminals

61 and 62 to melt the projection 31 of the upper case 8, and the upper case 8 and the lower The case 4 is joined by resistance welding.
[0031]
Further, in the first embodiment, both side walls 4b of the lower case 4 are pressed by the pressing jig 63 in the direction indicated by the arrow P. Thereby, the contact resistance at each projection 31 can be further stabilized, and more stable and reliable welding can be performed. Further, in this case, each projection 31 is crushed during welding, and the height of the projection 31 after welding can be set to approximately 0 mm, so that the outer dimensions can be suppressed and the gap between the joint surfaces of the two

cases

4 and 8 can be reduced. And the magnetic resistance between the

cases

4 and 8 can be reduced, and the electrical characteristics can be further improved. The left and right pressing jigs 63 may be used as electrode terminals of a resistance welding machine that contacts the lower case 4. That is, both 63 and 62 may be electrode terminals, or one of them may be an electrode terminal.
[0032]
The welding current supplied from the resistance welding machine is supplied from a single current setting control type power supply. This current setting control type power supply is an inverter type power supply, and can control all of the conditions at the beginning of current flow, the peak current, and the end of current flow. More specifically, a change in the welding current is detected, and the detection data is fed back to vary the applied voltage to set a desired welding current. By using this current setting control type power supply, even if the contact resistance between the

electrode terminals

61 and 62 of the resistance welding machine and the upper case 8 which is the workpiece is changed, the welding current value can be set to a desired value. Can be. Therefore, the influence on resistance welding can be reduced, and more stable resistance welding can be performed.
[0033]
As shown in FIG. 4, in the initial stage, the welding current is ramped up to 1800 A in 1 msec, and then applied at 1800 A for 2 msec. As shown in Table 1, the flow of such a relatively large current is such that the thermal conductivity of Ag or Cu is about 5 times that of Fe, and the metal plating coating layer (Ag plating layer and Cu plating layer) at a small current. This is because the heat generated in step (1) escapes and the metal plating coating layer cannot be melted effectively.
[0034]
As a result, the welding current is concentrated on the projection 31 having the smaller resistance among the four projections 31 formed on the joint surface of the upper case 8. As shown in Table 1, Ag and Cu have a lower melting point than Fe, so that the metal plating coating layer (Ag plating layer and Cu plating layer) at the tip contact portion of the projection 31 is melted by Joule heat. Then, when the metal base material (Fe plate) of the upper case 8 is exposed on the surface of the projection 31, the contact resistance value sharply increases because the resistance value of Fe is six times larger than that of Ag or Cu as shown in Table 1. . For this reason, the welding current flowing through the projection 31 is reduced, and the welding current is concentrated on the projection 31 having the next lowest resistance among the other projections 31 where the metal plating coating layer remains. In this way, the welding current is concentrated on the four protrusions 31 sequentially, and the metal plating coating layer at the tip contact portion of the protrusions 31 is melted to expose the metal base material (Fe plate).
[0035]
Thereafter, as shown in FIG. 4, the power supply is stopped for 50 msec, and the four protrusions 31 heated by Joule heat are cooled. By providing such a cooling period, even if the value of the welding current in the middle stage is too large, it is possible to prevent the occurrence of splash due to excessive welding.
[0036]
Next, the welding current in the middle stage is sharply raised and is supplied with electricity at 1800 A for 2 ms. Even if there are projections 31 in which the metal plating coating layer did not melt in the initial stage, this large welding current melts the metal plating coating layers of all the projections 31 and enables stable and reliable welding. Become.
[0037]
Thus, the metal base material (Fe plate) is exposed on the surfaces of all the projections 31 and resistance welding is started. Since the resistance value of the metal base material (Fe plate) is larger than that of Ag or Cu, the amount of heat generated at each projection 31 due to Joule heat is extremely large. Therefore, if the welding current is kept at 1800 A, the amount of the supplied current becomes excessively large, and the projection 31 may generate too much heat. In the worst case, the projection 31 may be melted.
[0038]
Therefore, the welding current is ramped down to 900 A in 8 ms for a period from the middle stage to the late stage of energization. Thereby, the welding current flowing through each projection 31 gradually decreases, and an excessive rise in temperature can be suppressed.
[0039]
As described above, after exposing the metal base material (Fe plate) on the surfaces of all the projections 31, the current is reduced as time passes to prevent an excessive temperature rise at the projections 31. By performing the welding at the portion 31, the two

cases

4, 8 are stably and reliably welded at the protruding portion 31, and the variation in the joining (welding) strength is reduced.
[0040]
Further, in the first embodiment, the side wall 8b serving as the joining surface of the upper case 8 and the side wall 4b serving as the joining surface of the lower case 4 are brought into contact only with the projection 31, so that the two

cases

4, 8 The contact resistance is stable. Furthermore, since the welding location (joining point) is limited to the location of the protruding portion 31, variations in the electric and magnetic circuits of the metal case are reduced. Therefore, variation in electrical characteristics is reduced, and electrical characteristics are improved.
[0041]
Note that the welding current condition is arbitrary, and for example, as shown in FIG. 5 and FIG. The welding current shown in FIG. 5 rises sharply in the initial stage, and is supplied with electricity at 1800 A for 2 msec, and then is decreased to 900 A in a period from the middle period to the latter period (8 msec). Also, the welding current shown in FIG. 6 is ramped up to 1800 A in 1 ms, and then ramped down to 0 A in 10 ms.
[0042]
Thus, the isolator 1 as shown in FIG. 7 is obtained. FIG. 8 is an electrical equivalent circuit diagram of the isolator 1.
[0043]
[Second embodiment, FIG. 9]
In the second embodiment, a mobile phone will be described as an example of the communication device according to the present invention.
[0044]
FIG. 9 is an electric circuit block diagram of the RF portion of the mobile phone 120. 9, 122 is an antenna element, 123 is a duplexer, 131 is a transmitting isolator, 132 is a transmitting amplifier, 133 is a bandpass filter for transmitting stages, 134 is a transmitting mixer, 135 is a receiving amplifier, and 136 is a receiving amplifier. 137 is a reception-side mixer, 138 is a voltage controlled oscillator (VCO), and 139 is a local band-pass filter.
[0045]
Here, the isolator 1 of the first embodiment can be used as the transmission-side isolator 131. By mounting this isolator 1, a mobile phone having excellent electrical characteristics at low cost can be realized.
[0046]
[Other embodiments]
The present invention is not limited to the above-described embodiment, and can be changed to various configurations within the scope of the present invention. For example, in the first embodiment, the present invention is applied to an isolator. However, the present invention can be applied to a circulator as well as other electronic components having a metal component formed by joining a plurality of metal members. The intersection angle of each of the center electrodes 21 to 23 may be in a range of 110 to 140 degrees. Further, the metal case may be divided into three or more. Further, the ferrite 20 is not limited to the rectangular parallelepiped shape, and may be another shape such as a disk or a hexagon.
[0047]
Further, in the above-described embodiment, two projections 31 are formed on both side walls 8b, which are joint surfaces of the upper case 8, respectively. However, the number of protrusions formed on one joint surface is one or more. Just fine.
[0048]
Further, in the above-described embodiment, the description has been given of the case where the projection 31 for welding is provided on the joining surface of the upper case 8. However, the projection 31 may be provided on the joining surface of the lower case 4. However, in order to obtain stable contact at the protrusion 31 and to reduce the cost of the case, the protrusion 31 is provided on the joint surface of one of the cases.
[0049]
In addition, the shape of the projection is not limited to that of the above-described embodiment, and may be substantially cylindrical, substantially rectangular cylindrical, substantially conical, or substantially pyramid-shaped, and the projection may be formed on the joining surface of the metal member. It is formed in a predetermined shape at a portion to be welded by press working or the like.
[0050]
【The invention's effect】
As is clear from the above description, according to the present invention, metal base materials having an electric resistance value smaller than that of the metal base material and having a metal coating layer having a melting point lower than that of the metal base material on the surface are simply separated from each other. When a plurality of protrusions are resistance-welded simultaneously by one power supply circuit, by reducing the conduction current during the period from the middle to the end of the conduction, resistance welding of the metal members can be performed stably and reliably. Therefore, it is possible to obtain a metal component or a metal case having a predetermined bonding strength and a small variation in the bonding strength, and to obtain a highly reliable and low-cost electronic component, a nonreciprocal circuit device, and a communication device.
[0051]
In addition, since simultaneous multipoint projection resistance welding can be performed stably, the number of assembling steps can be reduced and productivity can be improved as compared with the case where resistance welding is performed at each point separately. .
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing one embodiment of a non-reciprocal circuit device according to the present invention.
2A is a side view of the upper case shown in FIG. 1, and FIG. 2B is a plan view of the upper case.
FIG. 3 is a schematic sectional view showing a resistance welding method of the upper case and the lower case.
FIG. 4 is a graph showing an example of an energizing current condition.
FIG. 5 is a graph showing another example of the energizing current condition.
FIG. 6 is a graph showing still another example of a current supply condition;
FIG. 7 is an external perspective view of the non-reciprocal circuit device shown in FIG.
8 is an electrical equivalent circuit diagram of the non-reciprocal circuit device shown in FIG.
FIG. 9 is a block diagram showing an embodiment of a communication device according to the present invention.
[Explanation of symbols]
1: Isolator (non-reciprocal circuit device)
4 Lower case 8 Upper case 9 Permanent magnet 13 Center electrode assembly 20 Microwave ferrites 21 to 23 Center electrode 120 Cellular phone (communication device)

Claims

A resistance welding method in which metal base materials provided with a metal coating layer on the surface are welded to each other with protrusions formed on the metal base material,
The metal coating layer has an electric resistance value smaller than that of the metal base material, has a lower melting point than the metal base material, and when welding is simultaneously performed on a plurality of protrusions formed on the metal base material, A resistance welding method characterized by reducing a welding current in a period from a middle period to a final period.

The welding current in the initial stage of energization is relatively large, and the energizing time is relatively short, and the welding current in the period from the middle to the end of energization is gradually reduced to be relatively small, and The resistance welding method according to claim 1, wherein the energization time is relatively long.

The resistance welding method according to claim 1, wherein the welding current is set and controlled by a current setting control type power supply.

The resistance welding method according to any one of claims 1 to 3, wherein an energization suspension period is provided in the middle of the energization period.

An electronic component including a metal component configured by joining a plurality of metal members,
2. The plurality of metal members are each formed of a metal base material provided with a metal coating layer on a surface, and a plurality of protrusions are formed on a joining surface of at least one metal member of the plurality of metal members. An electronic component, wherein the projection is joined to a joining surface of another metal member by the resistance welding method according to claim 4.

A metal case configured by joining a plurality of metal members,
A permanent magnet housed in the metal case,
A ferrite housed in the metal case and to which a DC magnetic field is applied by the permanent magnet;
A plurality of center electrodes housed in the metal case and disposed on or inside the ferrite in an electrically insulated state and crossing each other,
2. The plurality of metal members are each formed of a metal base material provided with a metal coating layer on a surface, and a plurality of protrusions are formed on a joining surface of at least one metal member of the plurality of metal members. The projection is joined to the joining surface of another metal member by the resistance welding method according to any one of claims 4 to 5,
Non-reciprocal circuit device characterized by the above.

A communication device comprising at least one of the electronic component according to claim 5 and the non-reciprocal circuit device according to claim 6.