【０００１】
【産業上の利用分野】
本発明は、絶縁被覆導線の接合方法及び接合体に係り、特にコイル状に形成された絶縁被覆導線の両端部と、その両端部を包み込む導体端子とを接合し、接合中に絶縁被覆を除去して導電性及び機械的強度、耐食性に優れた接合部を得る絶縁被覆導線の接合方法及び接合体に関する。
【０００２】
【従来の技術】
コイル状に形成された絶縁被覆導体と、その絶縁被覆導体の一部を包込む導体端子とを接続する方法は、特公昭５０−１８９４０号及び特公昭５６−２８３５５号の各公報に見られるように、熱圧着方式が用いられている。この方式では絶縁導体が絶縁被覆で覆われているため通電出来ず、そこであらかじめ平行な２つの側辺部材と、その側辺部材の一方の端のそれぞれを接続する半環状部材とからなるＵ字形の導体端子の溝に絶縁被覆導体を挿入し、両側辺部材を上電極と下電極とで挾んで加圧し、電極間に電流を流すことによってＵ字形の導体端子を発熱させ、その熱で絶縁被覆を炭化させて除去し、絶縁被覆導体の芯線と導体端子を接触させて接続している。この接合方法では、抵抗溶接機を用いており、通電時間は短く、絶縁被覆導体の芯線と導体端子は機械的に接触するのみで、金属的接合とはなっていない。そのため結合強度を確保する手段として、加圧力によるかしめを利用した接続を採用しているが、疲労強度が低く、また長期使用に際し電気的特性が著しく低下する欠点があった。
【０００３】
その改良技術として、特開昭６１−１９９５７５号公報には絶縁被覆導体と導体端子間に接合用導体を配置し、それを溶融して絶縁被覆導体と導体端子を接続する方法が開示されている。接合用導体としてＣｕ−５０ＳｎやＣｕ−４５Ｚｎなどを使用例として示しているが、これらは溶融温度が高く被覆の炭化除去処理の加熱中に酸化し、その結果信頼性の高い接続が得られない欠点があった。
【０００４】
【発明が解決しようとする課題】
上記従来技術において、絶縁被覆導体と導体端子との結合部は金属的接合の観点において十分でなく、そのため機械的な接続強度が低く、振動並びにヒ−トサイクルなどの負荷による端子のゆるみに伴い電気的特性にも信頼性上問題があった。つまり、従来の接合方法は絶縁被覆の除去には有効であるが、信頼性の高い金属的接合を達成するには問題があった。
【０００５】
そこで、本発明においては、絶縁被覆導線の絶縁被覆を炭化することと、金属的接合（冶金的反応）を別々に考えることにした。すなわち、Ｕ字形状の導体端子を、絶縁被覆導線を挿入し保持する保持部と、導体端子の溝開口部が絶縁被覆導線を挾んで閉じられるような開口端部とからなる構造とし、このＵ字形状の導体端子の開口端部内面に比較的低融点成分の接合助剤（ろう材）を予め付着させ、そのＵ字形状の導体端子の保持部に絶縁被覆導線を挿入した状態で導体端子を、加圧し、通電加熱して、絶縁被覆導線の絶縁被覆を炭化して排出すると共に、開口端部内面を接合助剤の成分と導体端子の成分からなる合金層を介して金属的接合することにより、絶縁被覆導線と導体端子とを接合する強固な接合継手を実現できることを見出した。
【０００６】
本発明の目的は、絶縁被覆導線を包む込むように収納した導体端子の開口端部内面を、上記のように合金層を介して金属的接合を行なうことにより、高い接合強度及び耐熱性を有する接合継手が得られる絶縁被覆導線の接合方法及び接合体を提供することにある。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、本発明の絶縁被覆導線の接合方法は、略Ｕ字状に形成され、内面に接合助剤が付着された導体端子を準備する第１のステップと、前記導体端子の対向内面間に、該導体端子の開口端部を残して絶縁被覆導線を配置する第２のステップと、前記開口端部と前記絶縁被覆導線が配置された部分とを前記対向内面の外側から加圧するとともに、該絶縁被覆導線の絶縁被覆を炭化しかつ前記接合助剤を溶融する温度に通電加熱する第３のステップと、前記開口端部の前記対向内面にそれぞれ形成される該導電体端子の成分と前記接合助剤の成分との合金層同士が接合される圧力で、前記開口端部と前記絶縁被覆導線が配置された部分とを前記対向内面の外側から加圧する第４ステップとを有し、前記接合助剤は前記絶縁被覆導線の絶縁被覆の炭化温度より低い融点を有することを特徴としている。
【０００９】
接合助剤は、絶縁被覆の熱破壊温度より低い融点を有し、導体端子の材料と反応して接合助剤より高い融点の合金層を生成するものがよく、導体端子がＣｕ又はＦｅ系の材料から構成されている場合、接合助剤はＳｎ又はＺｎ、あるいはＳｎ，Ｚｎ，Ａｕ，Ａｇ，Ｐｂ，Ｐ，Ｐｄ，Ｃｕ及びＢｉのうちの２種類以上からなり４５０℃以下の融点を有するものを用いるのが好ましい。
【００１０】
また、絶縁被覆がＪＩＳ Ｃ ４００３に規定するＹ種からＡ，Ｅ，Ｂ，Ｆ，Ｈ及びＣ種のいずれかの絶縁被覆導線を対象としている。
【００１１】
また、第２段階で加圧する圧力は１〜５ ｋｇ／ｍｍ２が好ましく、圧力が１ ｋｇ／ｍｍ２以下では接合強度が十分でなく、５ ｋｇ／ｍｍ２以上では接合部が過度に変形するので好ましくない。
【００１２】
さらに、絶縁被覆導線の接合方法は、内面に接合助剤が付着された長穴の貫通穴を有する導体端子を準備する第１のステップと、前記貫通穴内に絶縁被覆導線を配置する第２のステップと、前記導体端子の前記絶縁被覆導線が配置された部分を含む全体を外側から加圧するとともに、該絶縁被覆導線の絶縁被覆を炭化しかつ前記接合助剤を溶融する温度に通電加熱する第３のステップと、前記絶縁被覆導線が配置されていない部分の前記貫通穴の対向内面にそれぞれ形成される該導電体端子の成分と前記接合助剤の成分との合金層同士が接合される圧力で、前記導体端子の前記絶縁被覆導線が配置された部分を含む全体を外側から加圧する第４ステップとを有し、前記接合助剤は前記絶縁被覆導線の絶縁被覆の炭化温度より低い融点を有するものとすることができる。この場合、導体端子は、２つの辺部材を重ね合わせて貫通穴が形成されていてもよい。
【００１３】
【作用】
本発明の絶縁被覆導線の接合方法を実施する接合装置として、加圧と通電加熱を行うことができる抵抗溶接機を用いるのが都合が良い。加熱と加圧が同時に出来、しかも、短時間で接合が出来ることによる。実際の接合作業では、大気中で接合出来るのが、量産、低コスト接合に好都合であり、この場合接合時間は短ければ短いほど酸素との反応が少ないため良好な継手が得られる。また、抵抗溶接機は接合部の信頼性をより高めるために、二段加熱、加圧方式を採用することが好ましい。
【００１４】
即ち、最初の一段目の加圧、通電では、絶縁被覆導線の絶縁被覆を炭化させることで、またこのとき接合助剤はその間絶縁被覆材より溶融温度が低いため溶融し、導体端子との反応が進み接合助剤と導体端子の母材との界面に合金層が形成される。その後二段目の加圧、通電で、炭化した絶縁被覆を接合面外へ排出させると同時に、端子界面に形成された合金層同士を介して加圧により端子を接触させて接合するものである。
【００１５】
このような種々の条件を満足する接合助剤は４５０℃以下の溶融温度で、しかも導体端子の母材と合金層を形成しやすい金属元素である必要がある。ここで端子はＣｕ及びＣｕ合金とすると、Ｃｕと反応性の良好な元素はＳｎ，Ｚｎ，Ａｕ，Ａｇ，Ｐ，Ｐｄなどであるが、融点を調整するためにはＰｂ、Ｂｉなども含有されていても良い。むしろ低融点化された成分の接合助剤の方が短時間の加熱の場合には合金層が形成され易く好都合である。
【００１６】
例えば、接合助剤としてＰｂ−５０％Ｓｎを用いた場合、その溶融温度は約２００℃である。コイルはポリエステル絶縁被覆（ＰＥＷと呼ぶ）の場合、炭化温度は約５５０℃であることから、まず一段目の加熱、加圧で少なくとも５５０℃以上に加熱される。その間Ｐｂ−５０Ｓｎは溶融し導体端子のＣｕ母材と反応し、導体端子との界面にＣｕ−Ｓｎの合金層が、また母材間の中央部には未反応のＰｂ，Ｓｎが形成されている。次に二段目の加熱、加圧によってＰＥＷの炭化物が排出され、被覆が除去された絶縁被覆導線の芯線同士及び導体端子とが電気的に接続される。一方、導体端子の開口部の接合は未反応なＰｂ，Ｓｎが接合面外へ押しやられ、接合部にはＣｕ−Ｓｎ合金層だけが残存する。合金層の厚さはほぼ２μｍであった。
【００１７】
この成分をＥＰＭＡにより分析するとＣｕ−２０〜３０％Ｓｎであり、Ｃｕ−Ｓｎ二元状態図から分かるように融点が７００℃以上となり、それに伴って接合強度も１０ｋｇｆ／ｍｍ２以上と向上する。このように低融点のはんだを用いるが、接合後の継手は高強度、高耐熱特性を有する。他の成分の接合助剤を適用しても同様な結果が得られる。形成される合金層としてはＡｕ−Ｓｎの場合、Ｃｕ−Ａｕ−Ｓｎが、Ｓｎ−Ａｇの場合はＣｕ−Ｓｎ−Ａｇが、Ｓｎ− Ｚｎの場合Ｃｕ−Ｓｎ−Ｚｎが，Ｚｎの場合はＣｕ−Ｚｎが夫々得られる。
【００１８】
Ｆｅ系の端子母材を接合する場合は、Ｃｕの代わりにＦｅが合金層に含有される。このようにして形成された合金層は１５０℃以上にも耐え、たとえ絶縁被覆材が損傷しても接合部は十分耐えることが出来る。なお、このような優れた特性を得るために、接合面に１〜５ｋｇｆ／ｍｍ２の加圧を与えることが必要である。
【００１９】
本発明が適用可能な絶縁被覆材は、加熱により溶融又は、炭化するものであれば全て該当する。すなわち、エナメル銅線（ＥＷ），ホルマ−ル銅線（ＰＶＦ），ポリエステル銅線（ＰＥＷ），及びアミド イミド銅線 （ＡＩＷ）など低耐熱性から高耐熱性まで適用できる。
【００２０】
【実施例】
以下、本発明の絶縁被覆導線の接合方法の一実施例を示す。図１は、コイル状に形成された絶縁被覆導線９の両端部をＵ字状導体端子５のＵ溝内に挿入して、それら絶縁被覆導線９と導体端子５（以後、端子５という）とを抵抗溶接法で接合する基本的な工程を示す図である。図２は抵抗溶接条件である加圧力及び溶接電流を示すチャートである。
【００２１】
図１（ａ）は、接合される部材の配置状態を示す図で、図中、抵抗溶接機の相対する上電極１と下電極４との間に、略Ｕ字形状の端子５が横たわった状態で挟まれ、さらに端子５のＵ溝の底にあたる部分には、絶縁被覆導線１０の両端部が端を同一方向に向けて挿入されている。本実施例で用いられたＵ字形状の端子５は、下電極４に当接する下辺部材７が真っ直ぐであり、一方、上電極１に当接する上辺部材６はＵ溝開口側で開口を閉じる方向に２段に成形されており、上辺部材６と下辺部材７とをつなぐ底に当たる部分は半円形状の半環状部材８である。上辺部材６は、さらに絶縁被覆導線１０を包む把持部分６ｂと、絶縁被覆導線１０から張り出した張出し部分６ａから成る。そして端子５のＵ溝内面には接合助剤９を予め付着させておく。この接合助剤の付着方法は一般的なやり方で良く、端子にクラッドさせておくか、粉末をペ−スト状にして塗布するか、溶射による吹き付け、箔をくるませるか、めっきによるか等種々の方法が適用可能である。
【００２２】
上電極１の先端は端子５の上辺部の形状に合わせて２段に形成され、端子５の把持部分６ｂに当接して絶縁被覆導体１０を接合する部分２と、端子５の張出し部に当接して端子５の開口端部を接合する部分３とから構成され、下電極４の先端は端子５の下辺の形状に合わせて平坦としている。絶縁被覆導線１０はＣｕの芯材１２とそれを被覆する絶縁被覆１１とから成っている。このように部材を配置した状態では、図２に示すように加圧力Ｐ及び通電電流Ｉは零である。
【００２３】
図２（ｂ）は、第一段の通電加熱／加圧の工程における端子５と絶縁被覆導線１０の状態を示すもので、端子５が電極１，４により加圧されると共に、電流が上電極１、端子５及び下電極４を通じて流れ、端子５は抵抗熱を発生する。その抵抗熱により絶縁被覆１１が炭化される。加熱温度は絶縁被覆１１の炭化より少し高めとし、その時、接合助剤８も溶融し、端子５と接合助剤８の界面に端子中の成分と接合助剤の成分とが反応して合金層１３が形成される。通常この合金層の厚さは７μｍ以下である。
【００２４】
図１（ｃ） は第二段の通電加熱／加圧の工程を示すもので、図２に示すように加圧力Ｐ及び電流Ｉは第一段の通電加熱／加圧の工程におけるよりそれぞれ高くする。この時、炭化された絶縁被覆１１は溶融した接合助剤９の排出と共に端子５の接合面外へ排出され、Ｃｕの芯材１２同士、および芯材１２と導体端子５とが電気的に接続される。一方、加熱により端子５内面の合金層の反応が更に進み、加圧力の付与により、接合助剤８で端子５と未反応の成分のものが排出され、端子５の開口端部の合金層同士が金属的に接合される。この時の加圧力は１〜５ ｋｇ／ｍｍ２がよい。１ ｋｇ／ｍｍ２以下では接合強度が十分でなく、５ ｋｇ／ｍｍ２以上では接合部が過度に変形するので好ましくない。
【００２５】
〈実施例 １〉
Ｕ字形状の端子５としてＣｕ製のものを用い、絶縁被覆導線１０としてアミドイミド銅線（ＡＩＷ）を用い、また端子５の内面に形成する接合助剤８としてＳｎ−３．５％Ａｇ（溶融温度：約２３０℃）をめっきして付着させて、図１で説明した接合方法により絶縁被覆導線１０と端子５とを接合した。なお、抵抗溶接機の電極はＭｏで構成し、また端子接合面にかかる加圧力は２ｋｇｆ／ｍｍ２とした。
【００２６】
〈実施例 ２〉
端子５にＣｕ製のものを用い、絶縁被覆導線１０としてポリエステル銅線（ＰＥＷ）用い、接合助剤９にはＳｎ（溶融温度：約２４０℃）めっきを１０μｍ形成させ、図１で説明した接合方法によりＭｏ電極を介して通電加熱／加圧して、絶縁被覆導線１０と端子５とを接合した。その時の端子接合面にかかる加圧力は３ｋｇｆ／ｍｍ２とした。
【００２７】
〈比較例 １〉
実施例２の組合せで、端子接合面にかかる加圧力は、特別には付与しないで、同様に抵抗溶接機を用いて絶縁被覆導線１０と端子５とを接合した。
【００２８】
〈比較例 ２〉
図３に示すように端子５はその辺部の長さが短く、そのＵ溝に挿入した絶縁被覆導線から張り出す部分がなく、Ｃｕ製のものとし、絶縁被覆導線１０としてアミドイミド銅線（ＡＩＷ）を用い、接合助剤９にはＳｎ−３．５％Ａｇ（溶融温度：約２３０℃）をめっきして付着させ、通電加熱／加圧による抵抗溶接機を用いて絶縁被覆導線１０と端子５とを接合した。なお、電極材はＭｏを用い、加圧力は１ｋｇｆ／ｍｍ２とした。
【００２９】
以上の実施例１，２及び比較例１，２で得た接合体について引張試験を実施した。引張試験は、できるだけ真の接合強度が見られるように、端子５より突き出した導線１０の先端部分を切断して実施した。導線の先端部を切断したのは、先端部がそのまま残っていると、引張試験の際先端部が端子にひっ掛かって、くびれの効果がでるので、その効果を除去するためである。
【００３０】
その引張試験結果は、比較例１及び２で得た接合体においては、導線１０は導線１０と端子５との接合箇所からぬけた。又、１５０℃の高温引張試験においては、その高温引張強度は室温強度より低い値を示した。
【００３１】
それに対し、実施例１，２のごとく加圧力を付与して端子の開口部分の接合面を合金層を介して接合した接合体は、実施例のいずれの場合にも導線自身から破断した。また、１５０℃の高温引張試験においても導線から破断した。すなわち、接合箇所は母材以上の強度を有して健全であり、高い接合強度と高い耐熱性を示した。
【００３２】
また、接合部の接合状態を顕微鏡組織で観察したところ比較例の接合体では、端子と導線との接合界面に接合不良を示す黒い線が観察され、金属的接合は見られなかった。
【００３３】
それに対し、本発明の実施例１及び２では、導線と端子の接合部にも金属的接合が観察され、更に端子の両辺分部の接合部には良好な金属的接合が見られた。実施例１の合金層は、ＥＰＭＡ分析の結果からＣｕ−Ｓｎ−Ａｇが形成されていた。また、実施例２の合金層には、Ｃｕ−Ｓｎが形成されていた。これらの合金層は２〜４μｍ存在し、端子同士が合金層を介して金属的接合されている様子が観察された。
【００３４】
なお、この界面は最初の接合助剤の溶融温度、２３０℃，２４０℃より高い溶融温度に変化していることも確認され、耐熱性も向上することが分かった。
【００３５】
前述した引張試験で本発明の各実施例で得られた接合体が安定した強度を持つのは、接合助剤と導体端子の母材とが反応して合金層を形成し、その合金層同士で導体端子の開口部が閉じて金属接合（又は、冶金的接合とも呼ぶ）が十分達成されていることが大きな要因である。また、この状態は電気的にも非常に電気抵抗の低い安定した数値を示すことも分かった。
【００３６】
その他の接合助剤としてＡｕ−Ｓｎ，Ｚｎ単体もしくはＺｎ−Ｓｎ，Ｓｎ−Ｐｂ，Ｓｎ−Ｐなどのものを選択して使用しても良好な接合が行なわれ、長時間に渡る使用に際しても安定なものとなる。
【００３７】
上記各実施例では端子の接合面全面に助剤を付着させたが、本質的には端子同士が接合する部分だけで良い。端子としては実施例１，２で用いた変形Ｕ字形状の端子の他に、図４に示す断面がレーストラック形状のもの、図５に示す断面が長方形環状のもの、図６に示すように断面が凹状で両端にフランジ部を有する
フランジ付凹状片を一対にして構成した端子、図７に示すように短冊をレーストラック形状に巻いて両端部重ね合わせた端子、又は図８に示す様フランジ付凹状片と平板とを組み合わせた端子を用いても良い接合体が得られる。接合するべき導線として絶縁被覆付きのもの以外にも、予め被覆を剥離した導線と端子と組み合わせて用いても同様に耐熱性を有する接合体が得られる。また通電抵抗加熱の代りに超音波振動を付与することによっても、同様な被覆剥離及び端子部の合金層接合は達成することができる。
【００３８】
【発明の効果】
本発明によれば、導線絶縁被覆導線の接合方法を、Ｕ字形状の溝面の少なくとも開口端部に低融点の接合助剤を付着させたＵ字形状の導体端子のその溝内に絶縁被覆導線の端部を挿入し、第１段階の加圧／通電で絶縁被覆導線の絶縁被覆を炭化すると共に、接合助剤を溶融させて導体端子の開口端部の溝面に接合助剤より高い融点の合金層を形成し、第２段階の加圧／通電で炭化した絶縁被覆を導体端子と絶縁被覆導線の芯線間から排出すると共に、導体端子の溝の開口端を合金層を介して接合する方法としたので、導体端子が閉じて絶縁被覆導線の芯線を締め付け、合金層による金属接合により接合強度及び耐熱性に優れた、且つ電気的にも低い抵抗値を示す接合継手が得られ、この接合継手は長期間にわたり導電体として安定して使用することができる。
【００３９】
また、溝形状をＵ字形状の代わりに横長穴形状とした導体端子を用い、横長穴の端部に接合助剤を付着させて、上記同様の接合を行うことにより、接合強度及び耐熱性に優れ電気的接続の良好な、且つ耐久性のある接合継手を得ることができる。
【図面の簡単な説明】
【図１】本発明の一実施例における各段階での絶縁被覆導線とＵ字形状の導体端子の結合状態を示す断面図である。
【図２】本発明の一実施例における各段階での加圧力と通電電流を模式的に示す図である。
【図３】比較例の接合継手を示す断面図である。
【図４】横長穴を形成する導体端子の接合状態を示す断面図である。
【図５】横長穴を形成する導体端子の接合状態を示す断面図である。
【図６】本発明の応用例である導体端子の形状を示す断面図である。
【図７】本発明の応用例である導体端子の形状を示す断面図である。
【図８】本発明の応用例である導体端子の形状を示す断面図である。
【符号の説明】
１ 上電極
２ 上電極の先端部（絶縁被覆導線を加圧）
３ 上電極の先端部（導体端子の開口部を加圧）
４ 下電極
５ 導体端子
６ａ，６ｂ 導体端子の上側の側辺部材
７ 導体端子の下側の側辺部材
８ 導体端子の半環状部材
９ 接合助剤コイル
１０ 絶縁被覆導線
１１ 絶縁被覆
１２ Ｃｕ芯材
１３ 合金層[0001]
[Industrial applications]
The present invention relates to a method and a joined body for an insulated conductor, and more particularly, to joining both ends of a coil-shaped insulated conductor and conductor terminals wrapping both ends thereof, and removing the insulation during joining. TECHNICAL FIELD The present invention relates to a method and a joined body of an insulated wire for obtaining a joined portion having excellent conductivity, mechanical strength and corrosion resistance.
[0002]
[Prior art]
A method of connecting a coil-shaped insulated conductor and a conductor terminal enclosing a part of the insulated conductor is described in JP-B-50-18940 and JP-B-56-28355. In addition, a thermocompression bonding method is used. In this method, electricity cannot be applied because the insulated conductor is covered with an insulating coating, and there is a U-shape consisting of two parallel side members in advance and a semi-annular member connecting one end of each of the side members. Insert the insulating coating conductor into the groove of the conductor terminal, press the both side members between the upper electrode and the lower electrode, pressurize, and apply a current between the electrodes to generate heat in the U-shaped conductor terminal, and insulate with the heat The coating is removed by carbonization, and the core wire of the insulated coated conductor and the conductor terminal are brought into contact and connected. In this joining method, a resistance welding machine is used, the energization time is short, and the core wire of the insulated conductor and the conductor terminal only come into mechanical contact with each other, not metallic joining. For this reason, as a means for securing the bonding strength, connection using caulking by pressing force is employed, but there are drawbacks that the fatigue strength is low and the electrical characteristics are significantly reduced during long-term use.
[0003]
As an improved technique thereof, Japanese Patent Application Laid-Open No. 61-199575 discloses a method of disposing a joining conductor between an insulated conductor and a conductor terminal, melting the joint conductor and connecting the insulated conductor and the conductor terminal. . Although Cu-50Sn and Cu-45Zn are used as bonding conductors as examples, they have high melting temperatures and oxidize during heating of the carbonization removal treatment of the coating, and as a result, a highly reliable connection cannot be obtained. There were drawbacks.
[0004]
[Problems to be solved by the invention]
In the above prior art, the joint between the insulated conductor and the conductor terminal is not sufficient from the viewpoint of metallic bonding, so that the mechanical connection strength is low, and the terminal is loosened due to load such as vibration and heat cycle. The electrical characteristics also had a problem in reliability. That is, the conventional joining method is effective for removing the insulating coating, but has a problem in achieving highly reliable metallic joining.
[0005]
Therefore, in the present invention, carbonization of the insulating coating of the insulating-coated conductor and metallic bonding (metallurgical reaction) are separately considered. That is, the U-shaped conductor terminal has a structure comprising a holding portion for inserting and holding the insulated conductor, and an opening end in which the groove opening of the conductor terminal can be closed with the insulated conductor interposed therebetween. A bonding aid (brazing material) having a relatively low melting point component is previously adhered to the inner surface of the opening end of the U-shaped conductor terminal, and the conductor terminal is inserted in a state where the insulating coated conductor is inserted into the holding portion of the U-shaped conductor terminal. Is pressurized, energized and heated to carbonize and discharge the insulating coating of the insulated conductive wire and metallically join the inner surface of the open end via an alloy layer composed of a component of the joining aid and a component of the conductor terminal. As a result, it has been found that a strong joint for joining the insulated conductor and the conductor terminal can be realized.
[0006]
The object of the present invention is to have high bonding strength and heat resistance by performing metallic bonding on the inner surface of the open end of the conductor terminal housed so as to wrap the insulated conductor wire through the alloy layer as described above. An object of the present invention is to provide a method and a joined body of an insulated conductor wire from which a joint can be obtained.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a method of joining an insulated conductor of the present invention includes a first step of preparing a conductor terminal having a substantially U-shape and having a joining aid adhered to an inner surface thereof; A second step of disposing an insulated conductor while leaving the open end of the conductor terminal between the opposing inner surfaces of the conductor terminal; and disposing the open end and the portion where the insulated conductor is disposed from the outside of the opposing inner surface. with pressurized, the third step and the conductor collector terminals to the opposite inner surface Ru are respectively formed of the open end for electrically heating the insulating coating of the insulating coated conductive wire to a temperature to melt the carbonized and the joining auxiliary agent And pressurizing the opening end and the portion where the insulating coating conductor is disposed from outside the facing inner surface with a pressure at which the alloy layers of the component and the component of the bonding aid are bonded to each other. Yes, and the bonding aid the insulation to be It is characterized by having a lower carbonization temperature of the conductor of the insulating coating melting point.
[0009]
The joining aid has a melting point lower than the thermal breakdown temperature of the insulating coating, and preferably reacts with the material of the conductor terminal to form an alloy layer having a higher melting point than the joining aid. When made of a material, the joining aid is Sn or Zn, or Sn, Zn, Au, Ag, Pb, P, Pd, Cu and Bi, and has a melting point of 450 ° C. or less. It is preferable to use
[0010]
In addition, the insulating coating covers any of the insulating coating conductors of any of the types Y, A, E, B, F, H and C specified in JIS C 4003.
[0011]
Further, the pressure applied in the second stage is preferably 1 to 5 kg / mm 2. If the pressure is 1 kg / mm 2 or less, the joining strength is not sufficient, and if the pressure is 5 kg / mm 2 or more, the joint is excessively deformed. It is not preferred.
[0012]
Further, the method of joining the insulated conductors includes a first step of preparing a conductor terminal having a long through hole having an inner surface to which a joining aid is attached, and a second step of disposing the insulated conductor in the through hole. And pressurizing the entirety of the conductor terminal including the portion where the insulated wire is disposed from outside, and energizing and heating to a temperature at which the insulating coating of the insulated wire is carbonized and the bonding aid is melted. 3 and step, pressure alloy layers to each other are bonded with the component of the insulating coated conductive wire is component of the through-hole conductor conductor terminals on opposite inner surfaces Ru are respectively formed of the portion not arranged with the joining auxiliary agent in, the entire insulation coated conductive wire comprises a portion disposed possess a fourth step of pressure from the outside pressure, lower melting point than the carbonization temperature of the insulating coating of the joining aid the insulation coated conductive wire of the conductor terminal Have It can be as. In this case, the conductor terminal may be formed with a through hole formed by overlapping two side members.
[0013]
[Action]
It is convenient to use a resistance welding machine capable of performing pressurization and electric heating as a joining apparatus for performing the method of joining insulating coated conductors of the present invention. Heating and pressurizing can be performed simultaneously, and bonding can be performed in a short time. In the actual joining operation, joining in the atmosphere is convenient for mass production and low cost joining. In this case, a shorter joining time results in less reaction with oxygen, so that a better joint can be obtained. Further, it is preferable that the resistance welding machine employs a two-stage heating and pressurizing method in order to further enhance the reliability of the joint.
[0014]
That is, in the first stage of pressurization and energization, the insulating coating of the insulated conductive wire is carbonized, and at this time, the bonding aid melts because the melting temperature is lower than that of the insulating coating material, and reacts with the conductor terminal. And an alloy layer is formed at the interface between the joining aid and the base material of the conductor terminal. Then, the second stage of pressing and energizing discharges the carbonized insulating coating out of the bonding surface, and at the same time, the terminals are brought into contact with each other by pressing via the alloy layers formed at the terminal interface to join them. .
[0015]
It is necessary that the joining aid satisfying these various conditions be a metal element having a melting temperature of 450 ° C. or less and easily forming an alloy layer with the base material of the conductor terminal. Here, when the terminals are made of Cu and Cu alloy, elements having good reactivity with Cu are Sn, Zn, Au, Ag, P, Pd, etc., but Pb, Bi, etc. are also contained in order to adjust the melting point. May be. Rather, the bonding aid of the component whose melting point has been lowered is more convenient because the alloy layer is easily formed in the case of heating for a short time.
[0016]
For example, when Pb-50% Sn is used as a bonding aid, its melting temperature is about 200C. When the coil is made of polyester insulating coating (referred to as PEW), the carbonization temperature is about 550 ° C., so that the coil is first heated to at least 550 ° C. by heating and pressing. During that time, Pb-50Sn melts and reacts with the Cu base material of the conductor terminal, an alloy layer of Cu-Sn is formed at the interface with the conductor terminal, and unreacted Pb and Sn are formed at the center between the base materials. I have. Next, the carbides of the PEW are discharged by the second stage of heating and pressurization, and the cores of the insulated conductors and the conductor terminals, from which the coating has been removed, are electrically connected. On the other hand, unreacted Pb and Sn are pushed out of the bonding surface in the bonding of the opening of the conductor terminal, and only the Cu—Sn alloy layer remains in the bonding portion. The thickness of the alloy layer was approximately 2 μm.
[0017]
When this component is analyzed by EPMA, it is Cu-20 to 30% Sn. As can be seen from the Cu-Sn binary phase diagram, the melting point is 700 ° C or higher, and the bonding strength is accordingly improved to 10 kgf / mm 2 or higher. Although a solder having a low melting point is used, the joint after joining has high strength and high heat resistance. Similar results can be obtained by applying a bonding aid of another component. As an alloy layer to be formed, in the case of Au-Sn, Cu-Au-Sn, in the case of Sn-Ag, Cu-Sn-Ag, in the case of Sn-Zn, Cu-Sn-Zn, and in the case of Zn, Cu- -Zn are obtained respectively.
[0018]
When joining an Fe-based terminal base material, Fe is contained in the alloy layer instead of Cu. The alloy layer thus formed can withstand 150 ° C. or more, and even if the insulating coating material is damaged, the joint can sufficiently withstand it. In order to obtain such excellent characteristics, it is necessary to apply a pressure of 1 to 5 kgf / mm 2 to the joint surface.
[0019]
The insulating coating material to which the present invention can be applied corresponds to any material that can be melted or carbonized by heating. That is, it can be applied from low heat resistance to high heat resistance such as enameled copper wire (EW), formal copper wire (PVF), polyester copper wire (PEW), and amide imide copper wire (AIW).
[0020]
【Example】
Hereinafter, an embodiment of the method for bonding an insulated conductor of the present invention will be described. FIG. 1 shows a state in which both ends of an insulated conductor 9 formed in a coil shape are inserted into U-shaped grooves of a U-shaped conductor terminal 5, and the insulated conductor 9 and the conductor terminal 5 (hereinafter referred to as terminal 5) FIG. 3 is a view showing a basic process of joining the members by a resistance welding method. FIG. 2 is a chart showing a pressing force and a welding current which are resistance welding conditions.
[0021]
FIG. 1A is a view showing an arrangement state of members to be joined. In the figure, a substantially U-shaped terminal 5 is laid between opposing upper electrodes 1 and lower electrodes 4 of a resistance welding machine. Both ends of the insulated conductor 10 are inserted into the portion corresponding to the bottom of the U groove of the terminal 5 with the ends thereof facing in the same direction. In the U-shaped terminal 5 used in this embodiment, the lower side member 7 in contact with the lower electrode 4 is straight, while the upper side member 6 in contact with the upper electrode 1 closes the opening on the U groove opening side. The portion that contacts the bottom connecting the upper side member 6 and the lower side member 7 is a semicircular member 8 having a semicircular shape. The upper side member 6 further includes a grip portion 6b that wraps the insulated wire 10 and an overhang portion 6a that protrudes from the insulated wire 10. Then, a bonding aid 9 is previously attached to the inner surface of the U groove of the terminal 5. The method of adhering the bonding agent may be a general method, such as cladding the terminal, applying the powder in paste form, spraying by spraying, wrapping the foil, plating, etc. Is applicable.
[0022]
The tip of the upper electrode 1 is formed in two steps according to the shape of the upper side of the terminal 5, and contacts the gripping portion 6 b of the terminal 5 to join the insulated conductor 10 and the overhanging portion of the terminal 5. The lower electrode 4 is made flat in accordance with the shape of the lower side of the terminal 5. The insulated conductor 10 is composed of a Cu core material 12 and an insulative coating 11 covering the core material 12. In the state where the members are arranged as described above, the pressing force P and the conduction current I are zero as shown in FIG.
[0023]
FIG. 2 (b) shows the state of the terminal 5 and the insulated wire 10 in the first stage heating / pressing step, in which the terminal 5 is pressed by the electrodes 1 and 4 and the current is increased. It flows through the electrode 1, the terminal 5, and the lower electrode 4, and the terminal 5 generates resistive heat. The insulating coating 11 is carbonized by the resistance heat. The heating temperature is set to be slightly higher than the carbonization of the insulating coating 11, and at that time, the bonding aid 8 also melts, and the interface between the terminal 5 and the bonding aid 8 reacts with the component in the terminal and the component of the bonding aid to form an alloy layer. 13 are formed. Usually, the thickness of this alloy layer is 7 μm or less.
[0024]
FIG. 1 (c) shows a second-stage energizing heating / pressing process. As shown in FIG. 2, the pressing force P and the current I are higher than those in the first-stage energizing heating / pressing process, respectively. I do. At this time, the carbonized insulating coating 11 is discharged out of the bonding surface of the terminal 5 together with the discharge of the molten bonding aid 9, and the Cu cores 12 and the core 12 and the conductor terminals 5 are electrically connected. Is done. On the other hand, the reaction of the alloy layer on the inner surface of the terminal 5 further proceeds by heating, and by applying a pressing force, components that have not reacted with the terminal 5 are discharged by the bonding aid 8, and the alloy layers at the opening end of the terminal 5 are separated from each other. Are metallically joined. The pressure at this time is preferably 1 to 5 kg / mm 2 . If it is 1 kg / mm 2 or less, the joining strength is not sufficient, and if it is 5 kg / mm 2 or more, the joint is excessively deformed, which is not preferable.
[0025]
<Example 1>
A U-shaped terminal 5 made of Cu is used, an amide-imide copper wire (AIW) is used as the insulated wire 10, and Sn-3.5% Ag (melted) is used as a bonding aid 8 formed on the inner surface of the terminal 5. (Temperature: about 230 ° C.) was applied by plating, and the insulated conductor 10 and the terminal 5 were joined by the joining method described with reference to FIG. The electrode of the resistance welding machine was made of Mo, and the pressure applied to the terminal joining surface was 2 kgf / mm 2 .
[0026]
<Example 2>
The terminal 5 is made of Cu, the copper wire (PEW) is used as the insulated conductor 10, the Sn (melting temperature: about 240 ° C.) plating is formed to 10 μm on the bonding aid 9, and the bonding described in FIG. Heating / pressurization was carried out through the Mo electrode by the method to join the insulated conductor 10 and the terminal 5. The pressure applied to the terminal joining surface at that time was 3 kgf / mm 2 .
[0027]
<Comparative Example 1>
In the combination of Example 2, the insulating coating conductor 10 and the terminal 5 were similarly joined using a resistance welding machine without applying a pressing force to the terminal joining surface.
[0028]
<Comparative Example 2>
As shown in FIG. 3, the terminal 5 has a short side, has no portion protruding from the insulated conductor inserted into the U-groove, and is made of Cu. The insulated conductor 10 is an amide-imide copper wire (AIW). ), Sn-3.5% Ag (melting temperature: about 230 ° C.) is plated and adhered to the joining auxiliary agent 9, and the insulated conductor 10 and the terminal are connected by using a resistance welding machine by applying current / heating. 5 was joined. In addition, Mo was used for the electrode material, and the pressing force was 1 kgf / mm 2 .
[0029]
Tensile tests were performed on the joined bodies obtained in Examples 1 and 2 and Comparative Examples 1 and 2 above. The tensile test was performed by cutting the tip of the conductive wire 10 protruding from the terminal 5 so that the true bonding strength could be seen as much as possible. The reason why the leading end of the lead wire is cut off is that if the leading end remains as it is, the leading end is caught on the terminal during the tensile test, resulting in a necking effect.
[0030]
The results of the tensile test show that in the joined bodies obtained in Comparative Examples 1 and 2, the conducting wire 10 was removed from the joint between the conducting wire 10 and the terminal 5. In the high temperature tensile test at 150 ° C., the high temperature tensile strength showed a value lower than the room temperature strength.
[0031]
On the other hand, the joined bodies in which the pressing surfaces were applied and the joining surfaces of the opening portions of the terminals were joined via the alloy layer as in Examples 1 and 2 were broken from the conducting wire itself in each case of the Examples. In addition, the wire broke from the conductor even in a high-temperature tensile test at 150 ° C. In other words, the joints had a strength higher than that of the base material, were sound, and exhibited high joint strength and high heat resistance.
[0032]
When the bonding state of the bonding portion was observed with a microstructure, a black line indicating poor bonding was observed at the bonding interface between the terminal and the conductive wire in the bonded body of the comparative example, and no metallic bonding was observed.
[0033]
On the other hand, in Examples 1 and 2 of the present invention, metallic joining was also observed at the joining portion between the conductor and the terminal, and good metallic joining was seen at the joining portion on both sides of the terminal. According to the result of EPMA analysis, Cu-Sn-Ag was formed in the alloy layer of Example 1. Further, Cu-Sn was formed in the alloy layer of Example 2. These alloy layers existed at 2 to 4 μm, and it was observed that the terminals were metallically joined to each other via the alloy layer.
[0034]
In addition, it was also confirmed that this interface had changed to a melting temperature higher than the initial melting temperature of the joining auxiliary agent, 230 ° C. or 240 ° C., and it was found that the heat resistance was also improved.
[0035]
The joint obtained in each of the examples of the present invention in the tensile test described above has a stable strength because the bonding aid reacts with the base material of the conductor terminal to form an alloy layer, and the alloy layers are bonded together. A major factor is that the opening of the conductor terminal is closed and metal bonding (or metallurgical bonding) is sufficiently achieved. It was also found that this state shows a stable numerical value with very low electric resistance.
[0036]
Good bonding is achieved even when Au-Sn, Zn alone or Zn-Sn, Sn-Pb, Sn-P, etc. are selected and used as other bonding aids, and are stable even when used for a long time. It becomes something.
[0037]
In each of the above embodiments, the auxiliary agent is adhered to the entire joint surface of the terminals. However, only the portion where the terminals are joined is essentially required. As the terminals, in addition to the modified U-shaped terminals used in Examples 1 and 2, the cross-section shown in FIG. 4 has a racetrack shape, the cross-section shown in FIG. 5 has a rectangular ring shape, and as shown in FIG. A terminal composed of a pair of concave concave pieces with flanges having flanges at both ends with a concave cross section, a terminal obtained by winding a strip into a race track shape as shown in FIG. 7 and overlapping both ends, or a flange as shown in FIG. A joined body may be obtained in which a terminal combining the concave piece and the flat plate may be used. A joined body having heat resistance can also be obtained by using a conductor to be joined in combination with a terminal and a conductor whose coating has been peeled off in addition to the one with an insulating coating. The same coating peeling and bonding of the alloy layer of the terminal portion can be achieved by applying ultrasonic vibration instead of the electric resistance heating.
[0038]
【The invention's effect】
According to the present invention, a method of bonding a conductive wire with an insulated wire is performed by applying a low melting point bonding aid to at least an open end of a U-shaped groove surface in a U-shaped conductor terminal in the groove. The end of the conductor is inserted, and the insulation coating of the conductor is carbonized by the first stage of pressurization / energization, and the joining aid is melted to form a groove higher than the joining aid on the groove surface at the open end of the conductor terminal. Forming an alloy layer having a melting point, discharging the insulating coating carbonized by the second-stage pressurization / energization from between the conductor terminal and the core of the insulating-coated conductor, and joining the open end of the groove of the conductor terminal via the alloy layer. As a result, the conductor terminal is closed, the core wire of the insulated conductor is tightened, and a metal joint by the alloy layer is used to obtain a joint having excellent joining strength and heat resistance, and also exhibiting an electrically low resistance value, This joint is used stably as a conductor for a long time. It is possible.
[0039]
Also, by using a conductor terminal having a groove shape instead of a U-shape in the shape of a horizontally long hole and attaching a bonding aid to the end of the horizontally long hole and performing the same bonding as described above, the bonding strength and heat resistance are improved. A durable joint having excellent electrical connection and good durability can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a coupling state between an insulated conductor and a U-shaped conductor terminal at each stage in one embodiment of the present invention.
FIG. 2 is a diagram schematically showing a pressing force and an energizing current at each stage according to an embodiment of the present invention.
FIG. 3 is a sectional view showing a joint of a comparative example.
FIG. 4 is a cross-sectional view showing a joined state of conductor terminals forming a horizontally long hole.
FIG. 5 is a cross-sectional view showing a joining state of conductor terminals forming a horizontally long hole.
FIG. 6 is a sectional view showing a shape of a conductor terminal which is an application example of the present invention.
FIG. 7 is a sectional view showing a shape of a conductor terminal which is an application example of the present invention.
FIG. 8 is a sectional view showing a shape of a conductor terminal which is an application example of the present invention.
[Explanation of symbols]
1 Upper electrode 2 Tip of upper electrode (Pressing the insulation-coated conductor)
3 Tip of the upper electrode (pressing the opening of the conductor terminal)
Reference Signs List 4 Lower electrode 5 Conductor terminal 6a, 6b Upper side member of conductor terminal 7 Lower side member of conductor terminal 8 Semi-annular member of conductor terminal 9 Joining aid coil 10 Insulation-coated conductor 11 Insulation coating 12 Cu core material 13 Alloy layer
