JP2004017060A

JP2004017060A - Iron tip for soldering iron

Info

Publication number: JP2004017060A
Application number: JP2002172347A
Authority: JP
Inventors: Hisaharu Tamura; 田村　寿春
Original assignee: NIPPON BONKOOTO KK
Current assignee: NIPPON BONKOOTO KK
Priority date: 2002-06-13
Filing date: 2002-06-13
Publication date: 2004-01-22

Abstract

<P>PROBLEM TO BE SOLVED: To provide an iron tip for a soldering iron, which has sufficient corrosion resistance to lead-free solder as well as to conventional solder and has sufficient wettability, and whose temperature is easily controlled. <P>SOLUTION: The iron tip comprises: an iron tip part 1 which is formed into a tapered shape, a cylindrical part 2 which is extended rearward from the rear-end outer edge of the iron tip part 1, a heat storage part 3 which is internally installed and packed in the cylindrical part 2, a heater part 4 (a heating means) which is arranged on the outer circumference of the cylindrical part 2, and a thermocouple 5 which is firmly fixed on the tip of the iron tip part 1. The iron tip part 1 and the cylindrical part 2 are integrally formed of Fe-Si alloy containing 6% Si. The heat storage part 3 is composed of bar-like copper materials densely packed. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、種々の半田を用いた半田付け作業に用いる半田ごて用こて先に関するものであり、特に鉛フリーの半田を用いた半田付け作業にも有効に用いることができる半田ごて用こて先に関するものである。
【０００２】
【従来の技術】
従来より半田として融点が低く被接合材料に対して濡れ性の良い鉛−錫（Ｐｂ−Ｓｎ）系の合金が用いられてきた。しかし、近年、公害問題で鉛の使用が制限されるようになり、これまでの鉛−錫系の半田に代えて錫−銀（Ｓｎ−Ａｇ）系や錫−亜鉛（Ｓｎ−Ｚｎ）系のいわゆる鉛フリー半田が用いられるようになってきた。
【０００３】
このような錫−銀系又は錫−亜鉛系のいわゆる鉛フリー半田は、鉛による公害の発生を回避するという目的は達成し得るものの、半田ごてのこて先に対する侵食作用が大きいこと、濡れ性が悪いこと、更には融点が高いことのような問題点が明らかになっている。
【０００４】
古くは半田ごて用こて先は銅材で構成されており、従来の鉛−錫共晶半田であっても侵食されやすい物であったため、これを回避すべく、その表面に鉄メッキを施したものが広く採用され、今日に至っている。このような鉄メッキを施した半田ごて用こて先は、上記のように、鉛−錫系の半田に対しては充分な耐食性を有することが長い使用経験からも実証されているが、前記のような鉛フリー半田に対しては、耐食性が不充分で、容易に侵食されてしまうことが明らかになっている。
【０００５】
更に前記のような鉛フリー半田では、既述のように、濡れ性が悪いため、こて先先端部に施した半田メッキが、半田付け作業時のクリーニング操作等により除去されると、半田の再付着が行われ難く、その結果、こて先が露出状態となることが多くその酸化が促進されることとなる。またこのように半田メッキが除去されると該半田メッキによる熱伝導も当然失われるため、一層、濡れ性も悪くなり、半田付け作業の能率が著しく低下することとなっているものである。
【０００６】
加えて前記のような鉛フリー半田では、これも先に述べたように、融点が既存の鉛−錫系の半田と比べて高いため、これに応じてこて先温度を上昇させる必要があり、その結果、半田付け作業時に使用するフラックスが炭化し、こて先に焼き付きが生じ易くなる傾向もある。更には接合対象の電子部品の熱的損傷を防止するため、負荷時には必要な温度を確保し、他方負荷の終了後には設定値を越えた無用の温度上昇（オーバーシュート）を防止すべく、精密な温度コントロールを必要とするようになる。
【０００７】
【発明が解決しようとする課題】
本発明は、以上のような従来技術の問題点を解消し、従来の鉛を含有する半田は勿論のこと、鉛フリー半田に対しても充分な耐食性を備え、かつ濡れ性も充分であって、温度コントロールも容易な半田ごて用こて先を提供することを解決の課題とする。
【０００８】
【課題を解決するための手段】
本発明の１は、こて先先端部の少なくとも半田と接触する部位を鉄−硅素合金で構成した半田ごて用こて先である。
【０００９】
本発明の２は、本発明の１の半田ごて用こて先に於いて、前記こて先先端部のコア部分を鉄−硅素合金で構成し、その後端に加熱手段を直列状態に配し、かつ蓄熱部を該こて先先端部のコア部分の途中から末端まで及びこれに直列状態に配した加熱手段に外装したものである。
【００１０】
本発明の３は、本発明の１の半田ごて用こて先に於いて、前記こて先先端部の全体を鉄−硅素合金で構成し、その後端外縁から同材質の筒状部を延長すると共に該筒状部内に蓄熱部を内装し、かつ該筒状部の外周に加熱手段を外装したものである。
【００１１】
本発明の４は、本発明の１、２又は３の半田ごて用こて先に於いて、前記鉄−硅素合金に於ける硅素の含有割合を０．３〜１．０％に設定したものである。
【００１２】
本発明の５は、本発明の２又は３の半田ごて用こて先に於いて、前記蓄熱部を銅材で構成したものである。
【００１３】
【発明の実施の形態】
本発明は、こて先先端部の少なくとも半田と接触する部位を鉄−硅素合金で構成した半田ごて用こて先である。
【００１４】
前記鉄−硅素合金は、鉛フリー半田に対する耐食性に優れたものであり、これで少なくともこて先先端部の半田と接触する部位を構成することにより、こて先の半田による侵食を回避し、その長寿命化を図ろうとするものである。このような鉄−硅素合金の優れた耐食性は、鉛フリー半田による侵食の実態の観察、その観察の結果に基づく侵食のメカニズムの解明、及びこれらに基づく侵食回避手段の推定と実証実験から見出したものである。
【００１５】
鉛フリー半田（９５．２％Ｓｎ−３．８％Ａｇ−１．０％Ｃｕ）によって侵食された従来の半田ごて用こて先の鉄メッキ部分を侵食方向にカットして、その断面を分析電子顕微鏡（ＳＥＭ−ＥＤＸ）で観察して見ると、鉄（Ｆｅ）はその結晶粒界に沿って侵食されていることが分かる。半田中の錫（Ｓｎ）は鉄の結晶粒内及び粒界の全体に浸入しており、他方、銀（Ａｇ）は鉄の結晶粒界に浸入していることが分かる。このことから鉄の結晶粒界には錫及び銀のいずれもが侵食すること、更に錫の侵食力は大きく、鉄の結晶粒内にまで侵食すると云うことが分かる。
【００１６】
以上のような観察の結果から、特に錫の侵食力を抑制できれば、錫（Ｓｎ）が成分の大部分を占める殆どの鉛フリー半田による侵食をかなりの程度防止できるのではないかとの推測が可能となり、更にそのような観点から鉄−硅素合金が有力であると推定したものである。即ち、硅素は鉄に添加すると、ＦｅＳｉ等の金属間化合物を形成し易く、そのため鉄−硅素合金では、その結晶粒界中にＳｉ金属間化合物が析出している可能性があり、加えて硅素と錫とは相互に殆ど溶け合わない関係にあるからである。そのような性質の故に鉛フリー半田中の錫は鉄−硅素合金の結晶粒界に侵食し難いものであると推定される。
【００１７】
以上の推定の下に、硅素の鉄に対する含有割合を種々に変えて多数の耐食試験を行ったが、ここではその一部を示すこととする。即ち、以下の表に示す割合で硅素を添加した鉄−硅素合金を試験片として行った耐食試験の結果を後記表１に示す。
【００１８】
＜耐食試験の方法＞
▲１▼ヒータを備えた丸棒銅材の先端に試験片を取り付け、これを試験用ロボットにセットし、ヒータで試験片を加熱しながら糸半田を送り出して接触させ、こうして試験片に付着した半田はエアーによって除去する。このような動作を繰り返し行った。
▲２▼以上に於いて、
試験片：Ｎｏ．１〜３は２．０ｍｍ厚みの短冊状鉄−硅素合金片、Ｎｏ．４は１．６７０ｍｍ厚みの短冊状の銅片に０．３３０ｍｍのＦｅメッキを施したもの。
試験片に対する加熱温度　：　３９０℃
糸半田の１ポイント当たりの送り量　：　２０ｍｍ／回
繰り返しポイント数　：　１７０００回
糸半田の径　：　φ０．８
糸半田の材質　：　９５．２％Ｓｎ−３．８％Ａｇ−１．０％Ｃｕ（鉛フリー半田）
【００１９】
【表１】

【００２０】
表１に示す耐食試験の結果から、従来の半田ごて用こて先に採用されていた構成であるＮｏ．４のＦｅメッキ品よりＮｏ．１〜３の鉄−硅素合金の方が侵食量が小さく、かつ鉄−硅素合金の中では、硅素の割合が大きい程侵食量が小さくなっていることが分かる。
【００２１】
このような試験片間相互の関係を以下により具体的に検討する。
Ｎｏ．４のＦｅメッキ品の侵食量は、試験打ち切りとなった供給ポイント８０００回時点のものであるので、Ｎｏ．１〜３までの侵食量も全て８０００回時点のそれに換算すると、次の通りになる。
Ｎｏ．１　：　０．１８３（ｍｍ）
Ｎｏ．２　：　０．１３９
Ｎｏ．３　：　０．０９１
Ｎｏ．４　：　０．３３０
そこで、Ｎｏ．１〜３のそれぞれの侵食量の値をＮｏ．４の侵食量の値で除してみると、その値は、それぞれ
Ｎｏ．１　：　約０．５５４
Ｎｏ．２　：　約０．４２１
Ｎｏ．３　：　約０．２７５
となり、Ｎｏ．４の侵食量に対して、Ｎｏ．１は約５５％、Ｎｏ．２は約４２％、Ｎｏ．３は約２７％の侵食割合であることが分かる。これらを耐久性の観点、即ち、Ｎｏ．４の侵食量に達するまでの鉛フリー半田との接触回数の倍率の観点から換算すると、
Ｎｏ．４との比較に於ける耐久性は、
Ｎｏ．１　：　約１．８０倍
Ｎｏ．２　：　約２．３７倍
Ｎｏ．３　：　約３．６３倍
であるということができる。
【００２２】
以上の検討結果から、鉄−硅素合金は鉄よりも鉛フリー半田に対する耐食性に優れ、鉄−硅素合金の中では、硅素の含有割合が大きい程耐食性が大きいことが確認できる。
【００２３】
他方、半田ごて用こて先は、半田との濡れ性に優れたものである必要があるが、これについては、定量的な検討ではなく、耐久性の試験の過程に於けるそれぞれの試験片の半田による濡れ状態を目視観察することで結論を得た。これによれば、鉄−硅素合金は硅素の含有割合が１．４％になると濡れ性が悪くなり、実用的とは言い難いものになることが分かった。更に硅素の割合が１．２％の場合は、前記のような鉛フリー半田との接触回数が１５０００回を越えると濡れ性が悪くなることも明らかになった。
【００２４】
従って前記耐久性の観点と以上の半田との濡れ性の観点から、こて先先端部の半田と接触する部位を構成する鉄−硅素合金は、硅素の含有割合が０．３〜１．０％であるのが適当であり、０．５〜０．８％であるのが充分な耐久性と濡れ性を備えるものとなるためより好ましい。
【００２５】
以上のように、こて先先端部は、その少なくとも半田と接触することとなる部位を前記鉄−硅素合金で構成すべきものであり、その鉄−硅素合金の硅素の含有割合は、前記のように、耐久性及び濡れ性の観点から０．３〜１．０％が適当であり、０．５〜０．８％であればより好ましい。こて先先端部は、それ以外の部位は自由な素材で構成することができる。例えば、こて先先端部のコア部分を蓄熱性及び熱伝導性に優れた銅等の他の素材で構成し、その表面部分のみを該鉄−硅素合金で構成することも、こて先先端部全体を該鉄−硅素合金で構成することとすることもできる。なお前記こて先先端部の形状寸法等はその目的に応じて自由に設定することができる。
【００２６】
こて先には、鉄−硅素合金よりも熱容量の大きな材質で構成する蓄熱部を付加することができる。勿論、このような蓄熱部は、その材質、位置関係及び大きさ等を自由に設定することができる。
【００２７】
従って本発明の半田ごて用こて先によれば、こて先先端部の少なくとも半田と接触することとなる部位を鉄−硅素合金で構成したため、半田接合作業に於いて鉛フリー半田を使用したとしても、容易にこれが侵食を受けることなく、長期に渡って使用を継続することができる。またそのような鉛フリー半田を使用しても鉄−硅素合金の硅素含有割合を前記のように設定することにより、必要な濡れ性も確保でき、作業性に不都合を生じることもなく、良好な半田付け作業を行うことができる。
【００２８】
以上の本発明の半田ごて用こて先は、前記こて先先端部のコア部分を鉄−硅素合金で構成し、その後端に加熱手段を直列状態に配設し、かつ蓄熱部を該こて先先端部のコア部分の途中から末端まで及び該加熱手段に外装した構成とすることができる。
【００２９】
そして本発明の半田ごて用こて先をこのように構成すると、こて先先端部と蓄熱部との熱伝達が良好に行われるものであるため、前記耐久性及び濡れ性に関する効果に加えて、負荷時のこて先先端部の温度低下を極力抑えることができると共に、負荷終了後の急激な温度上昇（オーバーシュート）を抑える精密な温度制御を容易に行うことができるものとなる。
【００３０】
このような構成の半田ごて用こて先は、以下のような製造方法により極めて容易にこれを製造することができるものとなる。
即ち、鉄−硅素合金の芯材と蓄熱部素材の外周部とからなる棒状部材を予め用意しておき、該棒状部材をこて先の長さに切断し、その一端側を切削加工して鉄−硅素合金の露出する所望形状のこて先先端部を形成し、かつ他端部からその軸心に沿って穴開け加工をして筒状部を形成し、該筒状部中に加熱手段を装入する製造方法である。
【００３１】
このような製造方法によれば、前記長さに切断した棒状部材の一端をこて先先端部を形成すべく切削加工すると、自ずと、こて先先端部の先端付近では蓄熱部素材が削除されて鉄−硅素合金による芯材が露出し、芯材によるこて先先端部のコア部分が形成されることになり、かつこれに加えて他端から穴開け加工して加熱手段を装入する筒状部を形成すると、自ずと、こて先先端部の長さ方向途中からこて先後端部まで連続する蓄熱部素材による外周部が残存形成されることになり、云うまでもなく、これが蓄熱部となる。
【００３２】
そしてこのような製造方法を採用した場合は、こて先先端部のコア部分が鉄−硅素合金の無垢材で構成されることとなるため、表面にそのようなメッキを施したこて先先端部に比して索材組成が安定しており、長寿命となる。またメッキ品のこて先と異なりその研削等が可能である。加えてメッキ品のこて先より短時間で製造が可能である。
【００３３】
また本発明の半田ごて用こて先は、前記こて先先端部の全体を鉄−硅素合金で構成し、その後端外縁から同材質の筒状部を延長すると共に該筒状部内に蓄熱部を内装し、かつ該筒状部の外周に加熱手段を外装する構成を採用することができる。
【００３４】
そして本発明の半田ごて用こて先をこのように構成すると、こて先先端部と蓄熱部との熱伝達が良好に行われるものであるため、前記耐久性及び濡れ性に関する効果に加えて、負荷時のこて先先端部の温度低下を極力抑えることができると共に、負荷終了後の急激な温度上昇（オーバーシュート）を抑える精密な温度制御を容易に行うことができるものとなる。
【００３５】
なお本発明の半田ごて用こて先に於いて、蓄熱部は銅材で構成するのが最適であり、そうすれば、該蓄熱部が充分な蓄熱能力を有するものであるため、こて先先端部に対して、負荷時にはその蓄熱している熱エネルギーを速やかに供給することで温度低下を許容限度内に保持させることができることとなる。
【００３６】
【実施例】
以下、添付図を参照しつつ本発明の実施例を説明する。
【００３７】
＜実施例１＞
図１（ａ）は実施例１の半田ごて用こて先の縦断面図、図１（ｂ）は実施例１の半田ごて用こて先の側面図、図２は実施例１の半田ごて用こて先を使用して半田付け作業を行った場合のそのこて先先端部の温度変化を示すグラフである。
【００３８】
この実施例１の半田ごて用こて先は、図１（ａ）及び（ｂ）に示すように、先細りテーパ状に形成したこて先先端部１と、該こて先先端部１の後端外縁部から後方に向かって延長した筒状部２と、該筒状部２に内装充填した蓄熱部３と、該筒状部２の外周に配したヒータ部（加熱手段）４と、こて先先端部１の先端に固着した熱電対５とで構成したものである。
【００３９】
硅素の含有割合が６％の鉄−硅素合金の棒材を用意し、その一端を先細りテーパ状に切削加工してこて先先端部１を形成し、かつ他端側から穴開け加工して筒状部２を形成し、更に該筒状部２中に棒状銅材を密に嵌め込み充填して蓄熱部３を構成したものである。
【００４０】
この実施例１では、こて先の長さＬ１：６０ｍｍ、筒状部２の外径Ｄ１：５ｍｍ、こて先先端部１の長さＬ２：１０ｍｍ、蓄熱部３の長さＬ３：５０ｍｍ、蓄熱部３の径Ｄ２：４ｍｍに設定して構成した。
【００４１】
この実施例１のこて先について前記耐久試験と同様の耐久試験を行ったところ、侵食量は０．３５８ｍｍであり、従来品を代表する前記Ｆｅメッキ品のそれと比べると、約５１％の侵食量であり、前記と同様にして耐久性を計算すると、約１．９６倍であることが分かる。従ってこの実施例１の半田ごて用こて先は、その組成が９５．２％Ｓｎ−３．８％Ａｇ−１．０％Ｃｕである鉛フリー半田に対して充分実用性のある耐久性を備えていることが分かる。更にこの耐久試験中の目視観察の結果によれば、半田の濡れ性にも問題はなかった。
【００４２】
なおこの実施例１の半田ごて用こて先の耐久試験は、既にこて先形状が形成されたものの試験であるので、試験片をヒータを備えた丸棒銅材の先端に取り付けるのに代えて、こて先自体をセットして、他は全て前記耐久試験と同一の方法及び条件で行ったものである。
【００４３】
次にこの実施例１の半田ごて用こて先を半田ごてに取り付け、その半田ごてを用いて基板にセットした多数の３Ｗのカーボン抵抗を手作業で連続的に半田付けし、その際のこて先先端部１の温度変化を調べた。図２は、このこて先先端部１の温度変化をプロットしたグラフである。こて先温度は３９０℃に制御すべく設定した。この半田付け作業でも、９５．２％Ｓｎ−３．８％Ａｇ−１．０％Ｃｕの鉛フリー半田を用いた。
【００４４】
図２に示すように、カーボン抵抗の半田付けを開始して、負荷がかかると、こて先先端部１は約４０℃ほど温度が低下するが、作業が終了して負荷がなくなると、直ちに設定温度である３９０℃に復帰し、特に大きなオーバーシュートも生じていない。また半田付け作業中は、その作業を安定した速さで繰り返していれば大きな変化はなく、前記のように、４０℃程低下したレベルを中心に、負荷に対する接触時に若干低下し、離間時に若干上昇する繰り返しが継続するだけである。
【００４５】
従ってこの実施例１の半田ごて用こて先によれば、鉛フリー半田に対して実用的に充分な耐久性を確保できるし、濡れ性にも問題はない。また半田付け作業時に、負荷から離れた直後に大きなオーバーシュートを起こすこともなく、温度コントロールも容易である。
【００４６】
＜実施例２、３、４＞
図３（ａ）は実施例２、３、４の半田ごて用こて先の縦断面図、図３（ｂ）は実施例２、３、４の半田ごて用こて先の側面図、図３（ｃ）は実施例２、３、４の半田ごて用こて先を製造するのに最適な素材の一部切欠側面図、図４は実施例２の半田ごて用こて先を使用して半田付け作業を行った場合のそのこて先先端部の温度変化を示すグラフ、図５は実施例３の半田ごて用こて先を使用して半田付け作業を行った場合のそのこて先先端部の温度変化を示すグラフ、図６は実施例４の半田ごて用こて先を使用して半田付け作業を行った場合のそのこて先先端部の温度変化を示すグラフである。
【００４７】
実施例２、３、４の半田ごて用こて先は、各部の寸法の点でのみ異なる同構成であるので、纏めて説明する。
【００４８】
実施例２、３、４の半田ごて用こて先は、図３（ａ）及び（ｂ）に示すように、コア部分１１ａを鉄−硅素合金で構成したこて先先端部１１と、その後端に直列状態に配設したヒータ部（加熱手段）１４と、該こて先先端部１１のコア部分１１ａの途中から末端まで及び該ヒータ部１４に外装した概ね筒状の蓄熱部１３と、こて先先端部１１に於けるコア部分１１の先端に固着した熱電対１５とで構成したものである。
【００４９】
前記こて先先端部１１は、図３（ａ）及び（ｂ）に示すように、コア部分１１ａの先端部を先細りテーパ形状に形成し、それより後方のストレートな部分は、ヒータ部１４に外装する蓄熱部１３の先端付近が外装状態となるように構成する。該蓄熱部１３は、その先端部を、こて先先端部１１のコア部分１１ａのテーパ形状を後方に延長するように同様の角度でテーパ状に形成し、蓄熱部１３のストレートな部分との境界までは、こて先先端部１１を兼ねる構成とする。
【００５０】
またこて先先端部１１のコア部分１１ａは、先に述べたように、鉄−硅素合金で構成すべきものであるが、この実施例２、３、４では、硅素の含有割合が８％のそれを用いた。更に蓄熱部１３としては銅材を用いた。
【００５１】
この実施例２、３、４の半田ごて用こて先は、以上のような構成であるため、以下のような製造方法により極めて容易にこれを製造することができる。
【００５２】
図３（ｃ）に示すように、予め硅素の含有割合が８％の鉄−硅素合金の円柱状芯材２１と、蓄熱部素材である銅材の外周部２２とからなる棒状部材２０を用意しておく。
該棒状部材２０をこて先の長さＬ４と同一長さに切断し、図３（ｂ）に示すように、その一端側を切削加工して先細りテーパ状のこて先先端部１１を形成し、かつ他端部からその軸心に沿って穴開け加工をして筒状部を形成し、該筒状部中にヒータ部１４を装入する。
【００５３】
以上のようにして、前記棒状部材２０の一端を先細りテーパ状に切削加工すると、自ずと、その先端付近では銅材の外周部２２が削除されて鉄−硅素合金による芯材が露出し、該部位にはこて先先端部１１のコア部分１１ａが形成され、かつその後方には銅材の外周部２２によるこて先先端部１１の後半部が形成されることとなる。更にこれに加えて他端から穴開け加工をしてヒータ部１４を装入する筒状部を形成すると、自ずと、こて先先端部１１の長さ方向途中からこて先後端部まで連続する銅材による外周部が残存形成されることになり、云うまでもなく、これが蓄熱部１３となるものである。
【００５４】
各部の寸法は、実施例２では、こて先の長さＬ４：６０ｍｍ、こて先先端部１１の長さＬ５：１１ｍｍ、こて先先端部１１のコア部分１１ａの外径Ｄ３：２ｍｍ、蓄熱部１３の外径Ｄ４：５．５ｍｍに設定して構成した。
【００５５】
実施例３では、こて先の長さＬ４：６０ｍｍ、こて先先端部１１の長さＬ５：１２ｍｍ、こて先先端部１１のコア部分１１ａの外径Ｄ３：２．５ｍｍ、蓄熱部１３の外径Ｄ４：６．５ｍｍに設定して構成した。
【００５６】
実施例４では、こて先の長さＬ４：６０ｍｍ、こて先先端部１１の長さＬ５：１２ｍｍ、こて先先端部１１のコア部分１１ａの外径Ｄ３：３ｍｍ、蓄熱部１３の外径Ｄ４：６．５ｍｍに設定して構成した。
【００５７】
この実施例２、３、４のこて先について実施例１のそれの耐久試験と全く同様の耐久試験を行ったところ、侵食量は各々０．２９０ｍｍ、０．２９９ｍｍ、０．２９５ｍｍであり、従来品を代表する前記Ｆｅメッキ品のそれと比べると、各々約４１％、約４２％、約４１％の侵食量であり、前記と同様にして耐久性を計算すると、各々約２．４３倍、約２．３８倍、約２．４３倍であることが分かる。従ってこれらの実施例２、３、４の半田ごて用こて先は、その組成が９５．２％Ｓｎ−３．８％Ａｇ−１．０％Ｃｕである鉛フリー半田に対して充分実用性のある耐久性を備えていることが分かる。更にこの耐久試験中の目視観察の結果によれば、半田の濡れ性にも問題はなかった。
【００５８】
次に以上の実施例２、３、４の半田ごて用こて先を半田付け作業に用いた際のこて先温度の変化を順次調べた。この半田付け作業でも、９５．２％Ｓｎ−３．８％Ａｇ−１．０％Ｃｕの鉛フリー半田を用いた。これを順次以下に示す。
【００５９】
まず実施例２の半田ごて用こて先を半田ごてに取り付け、その半田ごてを用いて基板にセットした多数の２Ｗのカーボン抵抗及び３Ｗのカーボン抵抗を手作業で連続的に半田付けし、その際のこて先先端部１１のコア部分１１ａの温度変化を調べた。図４は、このこて先先端部１１のコア部分１１ａの温度変化をプロットしたグラフである。こて先温度は３９０℃に制御すべく設定した。
【００６０】
図４に示すように、まず２Ｗのカーボン抵抗から半田付けを開始する。負荷がかかると、こて先先端部１１のコア部分１１ａは約４０℃ほど温度が低下するが、作業が終了して負荷がなくなると、直ちに設定温度である３９０℃に復帰し、特に大きなオーバーシュートも生じない。また半田付け作業中は、その作業が安定した速さで繰り返されていれば大きな変化はなく、前記のように、４０℃程低下した３５０℃のレベルを中心に、負荷に対する接触時に若干低下し、離間時に若干上昇する繰り返しが継続するだけである。その後、すぐに３Ｗのカーボン抵抗の半田付けを開始すると、２Ｗのそれの半田付けを行った場合と殆ど同様の温度変化の経過が見られるのみで、特別に変わった変化は見られない。２Ｗのカーボン抵抗から３Ｗのそれ程度の負荷の変化は大きな影響を与えないようである。
【００６１】
以上の結果から分かるように、この実施例２の半田ごて用こて先によれば、鉛フリー半田に対して実用的に充分な耐久性を確保できるし、濡れ性にも問題はない。更に半田付け作業時に、負荷から離れた直後に大きなオーバーシュートを起こすこともなく、温度コントロールも容易である。
【００６２】
次に実施例３の半田ごて用こて先を半田ごてに取り付け、その半田ごてを用いて基板にセットした各多数の１／４Ｗ、１Ｗ、２Ｗ及び３Ｗのカーボン抵抗を手作業で連続的に半田付けし、その際のこて先先端部１１のコア部分１１ａの温度変化を調べた。図５は、そのこて先先端部１１のコア部分１１ａの温度変化をプロットしたグラフである。こて先温度は３９０℃に制御すべく設定した。
【００６３】
図５に示すように、まず１／４Ｗのカーボン抵抗から半田付けを開始する。負荷がかかると、こて先先端部１１のコア部分１１ａは約３０℃ほど温度が低下するが、作業が終了して負荷がなくなると、直ちに設定温度である３９０℃に復帰し、特に大きなオーバーシュートも生じない。また半田付け作業中は、こて先先端部１１が負荷から離れている時間が僅かでも長くなると温度が少し上昇し、その時間が短くなるとやや下降するが、その作業が安定した速さで繰り返されていれば大きな変化はなく、前記のように、３０℃程低下した３６０℃のレベルを中心に、負荷に対する接触時に若干低下し、離間時に若干上昇する繰り返しが継続する状態になる。
【００６４】
１／４Ｗのカーボン抵抗の半田接合作業の後、すぐに１Ｗのカーボン抵抗、その後すぐに２Ｗのカーボン抵抗、更にその後すぐに３Ｗのカーボン抵抗の半田付け作業が同様に行われ、図５に示すように、順次、少しずつ各半田付け作業毎に温度低下が大きくなっていくが、最後の３Ｗのカーボン抵抗の半田付け作業で概ね４０度程度の低下であり、それほど大きな低下とはなっていない。また半田付け作業中の温度変化は、基本的に１／４Ｗのカーボン抵抗の半田付け作業の際の温度変化と変わらない。また半田付け作業が終了して負荷がなくなると、いずれの場合も温度は急上昇し、３９０℃に復帰するが、その際、特にオーバーシュートも生じない。
【００６５】
以上の結果から分かるように、この実施例３の半田ごて用こて先によれば、鉛フリー半田に対して実用的に充分な耐久性を確保できるし、濡れ性にも問題はない。更に半田付け作業時に、負荷から離れた直後に大きなオーバーシュートを起こすこともなく、温度コントロールも容易である。
【００６６】
次に実施例４の半田ごて用こて先を半田ごてに取り付け、その半田ごてを用いて基板にセットした各多数の１／４Ｗ、２Ｗ及び３Ｗのカーボン抵抗を手作業で連続的に半田付けし、その際のこて先先端部１１のコア部分１１ａの温度変化を調べた。図６は、そのこて先先端部１１のコア部分１１ａの温度変化をプロットしたグラフである。こて先温度は３９０℃に制御すべく設定した。
【００６７】
図６に示すように、まず１／４Ｗのカーボン抵抗から半田付けを開始する。負荷がかかると、この場合も、こて先先端部１１のコア部分１１ａは約２０℃ほど温度が低下するが、作業が終了して負荷がなくなると、直ちに設定温度である３９０℃に復帰し、特に大きなオーバーシュートも生じない。また半田付け作業中は、こて先先端部１１が負荷から離れている時間が僅かでも長くなると温度が少し上昇し、その時間が短くなるとやや下降するが、その作業が安定した速さで繰り返されていれば大きな変化はなく、前記のように、２０℃程低下した３７０℃のレベルを中心に、負荷に対する接触時に若干低下し、離間時に若干上昇する繰り返しが継続する状態になる。
【００６８】
１／４Ｗのカーボン抵抗の半田接合作業の後、すぐに２Ｗのカーボン抵抗、その後すぐに３Ｗのカーボン抵抗の半田付け作業が同様に行われ、図６に示すように、順次、少しずつ各半田付け作業毎に温度低下が大きくなっていくが、最後の３Ｗのカーボン抵抗の半田付け作業で概ね３５℃程度の低下であり、それほど大きな低下とはなっていない。また半田付け作業中の温度変化は、基本的に１／４Ｗのカーボン抵抗の半田付け作業の際の温度変化と変わらない。また半田付け作業が終了して負荷がなくなると、いずれの場合も温度は急上昇し、３９０℃に復帰するが、その際、特にオーバーシュートも生じない。
【００６９】
以上の結果から分かるように、この実施例４の半田ごて用こて先によれば、鉛フリー半田に対して実用的に充分な耐久性を確保できるし、濡れ性にも問題はない。更に半田付け作業時に、負荷から離れた直後に大きなオーバーシュートを起こすこともなく、温度コントロールも容易である。
【００７０】
【発明の効果】
本発明の１の半田ごて用こて先によれば、鉛フリー半田を使用した半田接合作業に於いて、こて先先端部の少なくとも半田と接触することとなる部位が鉄−硅素合金で構成されている物であるため、容易にこれが侵食を受けることなく、長期に渡って使用することができる長寿命を確保できる。またそのような鉛フリー半田であっても濡れ性も比較的良好であり、作業性に於ける問題もない。
【００７１】
本発明の２の半田ごて用こて先によれば、本発明の１の半田ごて用こて先と同様の効果を有することは云うまでもなく、更にこれに加えて、こて先先端部と蓄熱部との熱伝達が良好に行われるものであるため、負荷時のこて先先端部の温度低下を極力抑えることができると共に、負荷終了後の急激な温度上昇（オーバーシュート）を抑える精密な温度制御を容易に行うことができるものとなる。
【００７２】
また本発明の２の半田ごて用こて先は、前記のような構成であるため、鉄−硅素合金の芯材と蓄熱部素材の外周部とからなる棒状部材をこて先の長さに切断し、その一端側を切削加工して鉄−硅素合金の露出する所望形状のこて先先端部を形成し、かつ他端部からその軸心に沿って穴開け加工して筒状部を形成し、該筒状部中に加熱手段を装入することによって容易に製造することができる。
【００７３】
このような製造方法によれば、こて先先端部は前記棒状部材の芯材である鉄−硅素合金によって構成され、外周側の蓄熱部は、前記棒状部材の外周部である蓄熱部素材によって構成されることとなる。
【００７４】
そしてこのような製造方法を採用した場合は、こて先先端部のコア部分が鉄−硅素合金の無垢材で構成されることとなるため、表面にそのようなメッキを施したこて先先端部に比して索材組成が安定しており、長寿命となる。またメッキ品のこて先と異なりその研削等が可能である。加えてメッキ品のこて先より短時間で製造が可能である。
【００７５】
本発明の３の半田ごて用こて先によれば、本発明の１の半田ごて用こて先と同様の効果を有することは云うまでもなく、更にこれに加えて、こて先先端部と蓄熱部との熱伝達が良好に行われるものであるため、負荷時のこて先先端部の温度低下を極力抑えることができると共に、負荷終了後の急激な温度上昇（オーバーシュート）を抑える精密な温度制御を容易に行うことができるものとなる。
【００７６】
本発明の４の半田ごて用こて先によれば、鉛フリー半田を使用した半田接合作業に於いて、容易にこれが侵食を受けることなく、長期に渡って使用することができる。またそのような鉛フリー半田であっても濡れ性も比較的良好であり、作業性に於ける問題もない。
【００７７】
本発明の５の半田ごて用こて先によれば、充分な蓄熱能力を有するものであるため、こて先先端部に対して、負荷時にはその蓄熱している熱エネルギーを速やかに供給することで温度低下を許容限度内に保持させることができる。
【図面の簡単な説明】
【図１】（ａ）は実施例１の半田ごて用こて先の縦断面図。
（ｂ）は実施例１の半田ごて用こて先の側面図。
【図２】実施例１の半田ごて用こて先を使用して半田付け作業を行った場合のこて先先端部の温度変化を示すグラフ。
【図３】（ａ）は実施例２、３、４の半田ごて用こて先の縦断面図。
（ｂ）は実施例２、３、４の半田ごて用こて先の側面図。
（ｃ）は実施例２、３、４の半田ごて用こて先を製造するのに最適な素材の一部切欠側面図。
【図４】実施例２の半田ごて用こて先を使用して半田付け作業を行った場合のこて先先端部の温度変化を示すグラフ。
【図５】実施例３の半田ごて用こて先を使用して半田付け作業を行った場合のこて先先端部の温度変化を示すグラフ。
【図６】実施例４の半田ごて用こて先を使用して半田付け作業を行った場合のこて先先端部の温度変化を示すグラフ。
【符号の説明】
１　　こて先先端部
２　　筒状部
３　　蓄熱部
４　　ヒータ部（加熱手段）
５　　熱電対
１１　こて先先端部
１１ａ　こて先先端部のコア部分
１３　蓄熱部
１４　ヒータ部（加熱手段）
１５　熱電対
２０　棒状部材
２１　円柱状芯材
２２　外周部
Ｄ１　筒状部の外径
Ｄ２　蓄熱部の径
Ｄ３　こて先先端部のコア部分の外径
Ｄ４　蓄熱部の外径
Ｌ１　こて先の長さ
Ｌ２　こて先先端部の長さ
Ｌ３　蓄熱部の長さ
Ｌ４　こて先の長さ
Ｌ５　こて先先端部の長さ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a soldering iron used for soldering using various solders, and particularly to a soldering iron that can be effectively used for soldering using lead-free solder. It concerns the tip.
[0002]
[Prior art]
Conventionally, a lead-tin (Pb-Sn) -based alloy having a low melting point and good wettability with a material to be joined has been used as solder. However, in recent years, the use of lead has been restricted due to the problem of pollution, and tin-silver (Sn-Ag) -based and tin-zinc (Sn-Zn) -based solders have been used in place of conventional lead-tin solders. So-called lead-free solder has come to be used.
[0003]
Such a tin-silver-based or tin-zinc-based so-called lead-free solder can achieve the object of avoiding the pollution caused by lead, but has a large erosion effect on a soldering iron tip, and has a wettability. Problems such as poor properties and high melting point have been clarified.
[0004]
In the old days, the soldering iron tip was made of copper material, and even conventional lead-tin eutectic solder was susceptible to erosion, so iron plating was applied to the surface to avoid this. What has been applied has been widely adopted and continues to this day. Such iron-plated soldering iron tips are, as described above, proven to have sufficient corrosion resistance to lead-tin-based solder from long use experience, It has been found that the lead-free solder as described above has insufficient corrosion resistance and is easily eroded.
[0005]
Further, as described above, since the lead-free solder has poor wettability, as described above, if the solder plating applied to the tip of the soldering tip is removed by a cleaning operation or the like at the time of the soldering operation, the solder is not soldered. Reattachment is difficult to perform, and as a result, the tip is often exposed, which promotes its oxidation. Further, when the solder plating is removed in this way, the thermal conductivity due to the solder plating is naturally lost, so that the wettability is further deteriorated and the efficiency of the soldering operation is significantly reduced.
[0006]
In addition, in the above-mentioned lead-free solder, as described above, the melting point is higher than that of the existing lead-tin-based solder, so it is necessary to increase the tip temperature accordingly. As a result, the flux used at the time of the soldering operation is carbonized, and there is a tendency that seizure easily occurs on the tip. Furthermore, in order to prevent thermal damage to the electronic components to be joined, the required temperature must be maintained at the time of load, and after the load has been completed, the temperature must be precisely adjusted to prevent unnecessary temperature rise (overshoot) exceeding the set value. Temperature control is required.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems of the prior art, and has sufficient corrosion resistance not only for conventional lead-containing solder but also for lead-free solder, and has sufficient wettability. Another object of the present invention is to provide a soldering iron tip that can easily control the temperature.
[0008]
[Means for Solving the Problems]
A first aspect of the present invention is a soldering iron tip in which at least a portion of the tip of the tip that comes into contact with the solder is made of an iron-silicon alloy.
[0009]
According to a second aspect of the present invention, in the soldering iron according to the first aspect of the present invention, the core at the tip of the iron tip is made of an iron-silicon alloy, and heating means is arranged in series at the rear end. In addition, the heat storage section is provided on a heating means arranged from the middle to the end of the core portion at the tip of the tip and in series with the tip.
[0010]
According to a third aspect of the present invention, in the soldering iron according to the first aspect of the present invention, the entire tip of the soldering tip is formed of an iron-silicon alloy, and a cylindrical portion of the same material is formed from the rear outer edge. The heat storage portion is extended inside the tubular portion, and a heating means is provided on the outer periphery of the tubular portion.
[0011]
According to a fourth aspect of the present invention, in the soldering iron of any one of the first to third aspects of the present invention, the content of silicon in the iron-silicon alloy is set to 0.3 to 1.0%. Things.
[0012]
According to a fifth aspect of the present invention, in the second or third aspect of the present invention, the heat storage section is made of a copper material.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is a soldering iron tip in which at least a portion of the tip of the iron tip that contacts the solder is made of an iron-silicon alloy.
[0014]
The iron-silicon alloy has excellent corrosion resistance to lead-free solder, and by configuring at least a portion of the tip of the tip that comes into contact with the solder, erosion by the solder of the tip is avoided. It is intended to extend the life. The excellent corrosion resistance of such iron-silicon alloys was found by observing the actual state of erosion by lead-free solder, elucidating the mechanism of erosion based on the results of the observation, and estimating erosion avoidance measures based on these and conducting demonstration experiments. Things.
[0015]
The iron-plated portion of a conventional soldering iron tip eroded by lead-free solder (95.2% Sn-3.8% Ag-1.0% Cu) is cut in the direction of erosion, and its cross section is cut. Observation with an analytical electron microscope (SEM-EDX) shows that iron (Fe) is eroded along its grain boundaries. It can be seen that tin (Sn) in the solder has penetrated into the crystal grains of iron and the entire grain boundary, while silver (Ag) has penetrated into the crystal grain boundaries of iron. From this fact, it can be understood that both tin and silver erode the crystal grain boundary of iron, and furthermore, the erosion power of tin is large and erodes into the crystal grains of iron.
[0016]
From the results of the above observations, it can be speculated that if the erosion power of tin can be particularly suppressed, erosion due to most of the lead-free solder in which tin (Sn) occupies most of the components can be prevented to a considerable extent. From such a viewpoint, it is presumed that the iron-silicon alloy is effective. That is, when silicon is added to iron, it is easy to form an intermetallic compound such as FeSi. Therefore, in an iron-silicon alloy, there is a possibility that the Si intermetallic compound is precipitated in the crystal grain boundaries, and in addition, silicon is added. This is because tin and tin hardly dissolve in each other. It is presumed that tin in the lead-free solder hardly erodes the grain boundaries of the iron-silicon alloy because of such properties.
[0017]
Under the above assumptions, a number of corrosion resistance tests were conducted with various ratios of silicon to iron, and some of them are shown here. That is, Table 1 shows the results of a corrosion resistance test performed using iron-silicon alloys to which silicon was added in the proportions shown in the following table as test pieces.
[0018]
<Corrosion resistance test method>
{Circle around (1)} A test piece was attached to the tip of a round bar copper material provided with a heater, and this was set on a test robot. The solder is removed by air. Such an operation was repeatedly performed.
(2) In the above,
Test piece: No. Nos. 1 to 3 are strip-shaped iron-silicon alloy pieces having a thickness of 2.0 mm. Reference numeral 4 denotes a strip-shaped copper piece having a thickness of 1.670 mm and Fe plating of 0.330 mm.
Heating temperature for test piece: 390 ° C
Feed amount per point of thread solder: 20mm / time
Number of repetition points: 17000 times
Diameter of thread solder: φ0.8
Material of thread solder: 95.2% Sn-3.8% Ag-1.0% Cu (lead-free solder)
[0019]
[Table 1]

[0020]
From the results of the corrosion resistance test shown in Table 1, it was found that No. 1 was the configuration adopted for the conventional soldering iron. No. 4 from the Fe plated product of No. 4. It can be seen that the iron-silicon alloys 1 to 3 have a smaller amount of erosion, and among iron-silicon alloys, the larger the proportion of silicon, the smaller the amount of erosion.
[0021]
The mutual relationship between the test pieces will be more specifically described below.
No. The amount of erosion of the Fe-plated product of No. 4 was at the point of 8000 times of the supply point where the test was terminated. When the erosion amounts of 1 to 3 are all converted to those at the time of 8000 times, the following is obtained.
No. 1: 0.183 (mm)
No. 2: 0.139
No. 3: 0.091
No. 4: 0.330
Then, No. The values of the erosion amounts of Nos. Dividing by the value of the erosion amount of 4
No. 1: About 0.554
No. 2: about 0.421
No. 3: About 0.275
No. For the erosion amount of No. 4, No. 1 is about 55%, No. 2 is about 42%, 3 indicates an erosion rate of about 27%. These were evaluated from the viewpoint of durability, that is, No. When converted from the viewpoint of the magnification of the number of contacts with lead-free solder until the erosion amount of 4 is reached,
No. The durability in comparison with 4,
No. 1: About 1.80 times
No. 2: About 2.37 times
No. 3: About 3.63 times
It can be said that.
[0022]
From the above examination results, it can be confirmed that the iron-silicon alloy is more excellent in corrosion resistance to lead-free solder than iron, and that the higher the content of silicon in the iron-silicon alloy, the greater the corrosion resistance.
[0023]
On the other hand, a soldering iron tip needs to have good wettability with solder, but this is not a quantitative study, but rather an individual test in the durability test process. The conclusion was obtained by visually observing the wet state of the piece with solder. According to this, it was found that the wettability of the iron-silicon alloy was deteriorated when the silicon content ratio was 1.4%, and it was not practical. Further, when the silicon content was 1.2%, it became clear that the wettability deteriorated when the number of contacts with the lead-free solder exceeded 15,000 times.
[0024]
Therefore, from the viewpoint of the durability and the wettability with the above solder, the iron-silicon alloy constituting the portion of the tip of the tip that comes into contact with the solder has a silicon content of 0.3 to 1.0. % Is appropriate, and 0.5 to 0.8% is more preferable because it has sufficient durability and wettability.
[0025]
As described above, the tip portion of the iron tip should have at least a portion that comes into contact with the solder made of the iron-silicon alloy, and the silicon-containing ratio of the iron-silicon alloy is as described above. In addition, from the viewpoint of durability and wettability, 0.3 to 1.0% is appropriate, and 0.5 to 0.8% is more preferable. The tip of the tip can be made of a free material at other portions. For example, the core portion of the tip of the tip may be made of another material such as copper having excellent heat storage and heat conductivity, and only the surface portion may be made of the iron-silicon alloy. The entire part may be made of the iron-silicon alloy. The shape and size of the tip of the tip can be freely set according to the purpose.
[0026]
A heat storage section made of a material having a larger heat capacity than an iron-silicon alloy can be added to the tip. Of course, such a heat storage unit can be freely set in its material, positional relationship, size, and the like.
[0027]
Therefore, according to the soldering iron tip of the present invention, since at least a portion of the tip of the tip that comes into contact with the solder is made of an iron-silicon alloy, lead-free solder is used in the soldering operation. Even so, it can easily be used for a long time without being eroded. Even when such a lead-free solder is used, the necessary wettability can be ensured by setting the silicon content ratio of the iron-silicon alloy as described above, and no problem occurs in workability and good Soldering work can be performed.
[0028]
In the above-mentioned soldering iron tip of the present invention, the core portion at the tip of the iron tip is made of an iron-silicon alloy, the heating means is arranged in series at the rear end, and the heat storage section is A configuration may be employed in which the heating means is provided from the middle to the end of the core portion at the tip of the tip and the heating means is provided.
[0029]
When the soldering iron tip of the present invention is configured in this manner, the heat transfer between the tip end of the soldering iron and the heat storage section is performed well, and in addition to the effects related to the durability and wettability described above. Thus, it is possible to minimize the temperature drop of the tip of the tip under load as much as possible, and to easily perform precise temperature control to suppress a sharp rise in temperature (overshoot) after the end of the load.
[0030]
The soldering iron tip having such a configuration can be manufactured very easily by the following manufacturing method.
That is, a rod-shaped member consisting of a core material of iron-silicon alloy and an outer peripheral portion of the heat storage section material is prepared in advance, the rod-shaped member is cut into a tip having a length, and one end side is cut. The tip of the iron-silicon alloy having a desired shape to be exposed is formed, and a hole is formed along the axis from the other end to form a cylindrical portion, and heating is performed in the cylindrical portion. It is a manufacturing method of charging means.
[0031]
According to such a manufacturing method, when one end of the rod-shaped member cut to the length is cut to form the tip of the tip, the heat storage portion material is naturally deleted near the tip of the tip of the tip. As a result, the core material of the iron-silicon alloy is exposed, and the core portion of the tip of the iron tip is formed of the core material. When the cylindrical portion is formed, an outer peripheral portion formed by the heat storage portion material that continues from the middle of the tip end portion of the tip in the length direction to the rear end portion of the tip naturally forms a residual portion. Department.
[0032]
If such a manufacturing method is adopted, the core portion of the tip of the iron tip is made of a solid material of iron-silicon alloy. The cord material composition is more stable than that of, and the life is long. Unlike the tip of a plated product, it can be ground or the like. In addition, it can be manufactured in a shorter time than the tip of a plated product.
[0033]
Further, in the soldering iron tip of the present invention, the entire tip of the iron tip is made of an iron-silicon alloy, and a cylindrical portion of the same material is extended from the outer edge of the rear end, and heat is stored in the cylindrical portion. It is possible to adopt a configuration in which the heating section is provided inside the cylindrical section and the heating means is provided on the outer periphery of the cylindrical section.
[0034]
When the soldering iron tip of the present invention is configured in this manner, the heat transfer between the tip end of the soldering iron and the heat storage section is performed well, and in addition to the effects related to the durability and wettability described above. Thus, it is possible to minimize the temperature drop of the tip of the tip under load as much as possible, and to easily perform precise temperature control to suppress a sharp rise in temperature (overshoot) after the end of the load.
[0035]
In the soldering iron tip of the present invention, it is optimal that the heat storage section is made of a copper material, and since the heat storage section has a sufficient heat storage capacity, When a load is applied to the tip end portion, the stored thermal energy is promptly supplied so that the temperature drop can be kept within an allowable limit.
[0036]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0037]
<Example 1>
FIG. 1A is a longitudinal sectional view of the soldering iron of the first embodiment, FIG. 1B is a side view of the soldering iron of the first embodiment, and FIG. It is a graph which shows the temperature change of the tip part when the soldering operation is performed using the soldering iron tip.
[0038]
As shown in FIGS. 1 (a) and 1 (b), the soldering iron tip of this embodiment 1 has a tip 1 formed in a tapered shape and a tip 1 of the tip 1. A tubular portion 2 extending rearward from a rear end outer edge portion, a heat storage portion 3 internally filled in the tubular portion 2, a heater portion (heating means) 4 arranged on an outer periphery of the tubular portion 2, The thermocouple 5 is fixed to the tip of the tip 1.
[0039]
An iron-silicon alloy bar having a silicon content of 6% is prepared, one end of the bar is cut into a tapered shape to form a tip 1 and a hole is drilled from the other end to form a cylinder. The heat storage portion 3 is formed by forming a cylindrical portion 2 and further tightly fitting and filling a rod-shaped copper material into the cylindrical portion 2.
[0040]
In the first embodiment, the length L1 of the tip is 60 mm, the outer diameter D1 of the cylindrical portion 2 is 5 mm, the length L2 of the tip 1 of the tip is 10 mm, the length L3 of the heat storage section 3 is 50 mm, The diameter D2 of the heat storage unit 3 was set to 4 mm.
[0041]
When a durability test similar to the above-described durability test was performed on the tip of Example 1, the amount of erosion was 0.358 mm, and the erosion amount was about 51% as compared with that of the Fe-plated product representing the conventional product. When the durability is calculated in the same manner as above, it is found that the amount is about 1.96 times. Therefore, the soldering iron tip of Example 1 has sufficient practical durability against lead-free solder having a composition of 95.2% Sn-3.8% Ag-1.0% Cu. It turns out that it is equipped with. Further, according to the result of visual observation during the durability test, there was no problem with the wettability of the solder.
[0042]
The endurance test of the soldering iron tip of the first embodiment is a test of a tip having a shape already formed. Therefore, it is necessary to attach a test piece to a tip of a round bar copper material provided with a heater. Instead, the tip itself was set, and all other steps were performed in the same manner and under the same conditions as in the above durability test.
[0043]
Next, the soldering iron tip of Example 1 was attached to the soldering iron, and a large number of 3 W carbon resistors set on the board were continuously soldered manually by using the soldering iron. The temperature change at the tip 1 of the tip was examined. FIG. 2 is a graph in which the temperature change of the tip 1 is plotted. The tip temperature was set to be controlled at 390 ° C. Also in this soldering operation, lead-free solder of 95.2% Sn-3.8% Ag-1.0% Cu was used.
[0044]
As shown in FIG. 2, when the load is applied after the soldering of the carbon resistor is started and the load is applied, the temperature of the tip portion 1 of the tip is lowered by about 40 ° C., but immediately after the work is completed and the load is removed. The temperature returns to the set temperature of 390 ° C., and no particularly large overshoot occurs. Also, during the soldering operation, there is no significant change if the operation is repeated at a stable speed, and as described above, the voltage slightly decreases at the time of contact with the load, and the voltage slightly decreases at the time of separation, centering on the level lowered by about 40 ° C. Only the rising repetition continues.
[0045]
Therefore, according to the soldering iron of the first embodiment, practically sufficient durability can be ensured with respect to lead-free solder, and there is no problem in wettability. Further, during the soldering operation, there is no large overshoot immediately after leaving the load, and the temperature control is easy.
[0046]
<Examples 2, 3, and 4>
FIG. 3A is a vertical cross-sectional view of the soldering irons of Examples 2, 3, and 4, and FIG. 3B is a side view of the soldering irons of Examples 2, 3, and 4. FIG. 3 (c) is a partially cutaway side view of a material most suitable for manufacturing the soldering iron tips of Examples 2, 3 and 4, and FIG. 4 is a soldering iron of Example 2. FIG. 5 is a graph showing the temperature change at the tip of the soldering tip when the soldering work is performed using the tip. FIG. 5 shows the soldering work performed using the soldering iron tip of the third embodiment. FIG. 6 is a graph showing the temperature change at the tip of the iron tip in the case shown in FIG. 6. FIG. 6 shows the temperature change at the tip of the iron tip when the soldering work is performed using the soldering iron of the fourth embodiment. FIG.
[0047]
The soldering iron tips of the second, third and fourth embodiments have the same configuration that differs only in the dimensions of each part, and will be described together.
[0048]
As shown in FIGS. 3 (a) and 3 (b), the soldering iron tips of Examples 2, 3, and 4 include a tip 11 having a core portion 11a made of an iron-silicon alloy. A heater portion (heating means) 14 disposed in series at the rear end; and a generally cylindrical heat storage portion 13 which is provided from the middle to the end of the core portion 11a of the tip portion 11 and is provided on the heater portion 14. And a thermocouple 15 fixed to the tip of the core portion 11 in the tip end portion 11.
[0049]
As shown in FIGS. 3 (a) and 3 (b), the tip portion 11 of the iron tip is formed by tapering the tip portion of the core portion 11a, and the straight portion behind the tip portion is connected to the heater portion 14. The heat storage unit 13 to be packaged is configured so that the vicinity of the distal end is in a packaged state. The heat storage section 13 is formed such that its tip end is tapered at a similar angle so as to extend the tapered shape of the core portion 11a of the tip end section 11 backward, and the heat storage section 13 is formed with a straight portion. Up to the boundary, the tip also serves as the tip 11.
[0050]
The core portion 11a of the tip portion 11 should be made of an iron-silicon alloy as described above. In Examples 2, 3, and 4, the silicon content was 8%. I used it. Further, a copper material was used for the heat storage unit 13.
[0051]
Since the soldering iron tips of Examples 2, 3, and 4 have the above-described configuration, they can be manufactured very easily by the following manufacturing method.
[0052]
As shown in FIG. 3 (c), a rod-shaped member 20 composed of a columnar core material 21 of an iron-silicon alloy having a silicon content of 8% and an outer peripheral portion 22 of a copper material as a heat storage part material is prepared in advance. Keep it.
The rod-shaped member 20 is cut to the same length as the length L4 of the tip, and as shown in FIG. 3B, one end is cut to form a tapered tip 11 having a tapered shape. Then, a hole is formed along the axis from the other end to form a tubular portion, and the heater portion 14 is inserted into the tubular portion.
[0053]
As described above, when one end of the rod-shaped member 20 is cut into a tapered shape, the outer peripheral portion 22 of the copper material is naturally deleted near the tip of the rod-shaped member 20 to expose the core material of the iron-silicon alloy. The core portion 11a of the tip end portion 11 is formed, and a rear half portion of the tip end portion 11 is formed behind the core portion 11a by an outer peripheral portion 22 of a copper material. In addition to this, if a cylindrical portion for inserting the heater portion 14 is formed by drilling from the other end, it naturally continues from the middle of the tip end portion 11 in the longitudinal direction to the tip rear end portion. The outer peripheral portion of the copper material is left, and it goes without saying that this becomes the heat storage section 13.
[0054]
In the second embodiment, the dimensions of each part are as follows: tip length L4: 60 mm, tip tip part length L5: 11 mm, outer diameter D3 of core part 11 a of tip tip part 11: 2 mm, The outer diameter D4 of the heat storage unit 13 was set to 5.5 mm.
[0055]
In the third embodiment, the length L4 of the tip is 60 mm, the length L5 of the tip 11 is 12 mm, the outer diameter D3 of the core portion 11 a of the tip 11 is 2.5 mm, and the heat storage section 13 is provided. The outer diameter D4 was set to 6.5 mm.
[0056]
In the fourth embodiment, the length L4 of the tip is 60 mm, the length L5 of the tip 11 is 12 mm, the outer diameter D3 of the core portion 11 a of the tip 11 is 3 mm, and the outer diameter of the heat storage section 13 is 3 mm. The diameter D4 was set to 6.5 mm.
[0057]
When the same durability test as that of Example 1 was performed on the tips of Examples 2, 3, and 4, the erosion amounts were 0.290 mm, 0.299 mm, and 0.295 mm, respectively. The erosion amounts are about 41%, about 42%, and about 41%, respectively, as compared with those of the above-mentioned Fe-plated products, which represent the conventional products. It turns out that it is about 2.38 times and about 2.43 times. Therefore, the soldering irons of Examples 2, 3, and 4 are sufficiently practical for lead-free solder whose composition is 95.2% Sn-3.8% Ag-1.0% Cu. It can be seen that it has a characteristic durability. Further, according to the result of visual observation during the durability test, there was no problem with the wettability of the solder.
[0058]
Next, changes in the temperature of the soldering iron tip when the soldering iron tips of Examples 2, 3, and 4 were used for a soldering operation were sequentially examined. Also in this soldering operation, lead-free solder of 95.2% Sn-3.8% Ag-1.0% Cu was used. This is shown below sequentially.
[0059]
First, the soldering iron tip of Example 2 was attached to the soldering iron, and a large number of 2W carbon resistors and 3W carbon resistors set on the substrate were continuously soldered manually using the soldering iron. Then, the temperature change of the core portion 11a of the tip portion 11 of the tip was examined. FIG. 4 is a graph in which the temperature change of the core portion 11a of the tip portion 11 is plotted. The tip temperature was set to be controlled at 390 ° C.
[0060]
As shown in FIG. 4, first, soldering is started from a 2 W carbon resistor. When a load is applied, the temperature of the core portion 11a of the tip portion 11 decreases by about 40 ° C., but when the work is completed and the load is removed, the temperature immediately returns to the set temperature of 390 ° C. No shoots occur. Also, during the soldering operation, there is no significant change if the operation is repeated at a stable speed, and as described above, the temperature slightly decreases at the time of contact with the load, centering on the level of 350 ° C. which has decreased by about 40 ° C. However, the repetition of slightly rising at the time of separation continues. Thereafter, when the soldering of the carbon resistor of 3 W is started immediately, almost the same temperature change as in the case of the soldering of 2 W is observed, and no special change is observed. A change in load from 2 W carbon resistance to 3 W does not appear to have a significant effect.
[0061]
As can be seen from the above results, according to the soldering iron of Example 2, practically sufficient durability can be ensured for the lead-free solder, and there is no problem in wettability. Further, during the soldering operation, a large overshoot does not occur immediately after leaving the load, and the temperature control is easy.
[0062]
Next, the soldering iron tip of Example 3 was attached to the soldering iron, and a large number of 1 / 4W, 1W, 2W, and 3W carbon resistors set on the substrate using the soldering iron were manually applied. The solder was continuously soldered, and the temperature change of the core portion 11a of the tip portion 11 of the soldering tip at that time was examined. FIG. 5 is a graph in which the temperature change of the core portion 11a of the tip portion 11 is plotted. The tip temperature was set to be controlled at 390 ° C.
[0063]
As shown in FIG. 5, first, soldering is started from a 1/4 W carbon resistor. When a load is applied, the temperature of the core portion 11a of the tip 11 decreases by about 30 ° C., but when the work is completed and the load is removed, the temperature immediately returns to the set temperature of 390 ° C. No shoots occur. Also, during the soldering operation, the temperature rises slightly when the time during which the tip 11 is away from the load is slightly increased, and decreases slightly when the time is reduced, but the operation is repeated at a stable speed. If there is no change, there will be no significant change, and as described above, the state will be such that the repetition of a slight decrease at the time of contact with the load and a slight increase at the time of separation is continued, centering on the level of 360 ° C. which has decreased by about 30 ° C.
[0064]
After the 1/4 W carbon resistance soldering operation, the 1 W carbon resistance immediately, 2 W carbon resistance immediately thereafter, and immediately thereafter, the 3 W carbon resistance soldering operation are similarly performed, as shown in FIG. As described above, the temperature drop gradually increases gradually with each soldering operation. However, the temperature drop is approximately 40 degrees in the last 3 W carbon resistance soldering operation, and is not so large. . The temperature change during the soldering operation is basically the same as the temperature change during the soldering operation of a 1/4 W carbon resistor. In addition, when the load is removed after the soldering operation is completed, the temperature rises rapidly in each case and returns to 390 ° C., but no particular overshoot occurs.
[0065]
As can be seen from the above results, according to the soldering iron of the third embodiment, practically sufficient durability can be ensured for the lead-free solder, and there is no problem in wettability. Further, during the soldering operation, a large overshoot does not occur immediately after leaving the load, and the temperature control is easy.
[0066]
Next, the soldering iron tip of Example 4 was attached to the soldering iron, and a large number of 1 / 4W, 2W and 3W carbon resistors set on the board were continuously and manually set using the soldering iron. Then, the temperature change of the core portion 11a of the tip 11 of the soldering tip at that time was examined. FIG. 6 is a graph in which the temperature change of the core portion 11a of the tip portion 11 is plotted. The tip temperature was set to be controlled at 390 ° C.
[0067]
As shown in FIG. 6, first, soldering is started from a 1/4 W carbon resistor. When a load is applied, the temperature of the core portion 11a of the tip portion 11 of the tip 11 drops by about 20 ° C., but when the work is completed and the load is removed, the temperature immediately returns to the set temperature of 390 ° C. No particularly large overshoot occurs. Also, during the soldering operation, the temperature rises slightly when the time during which the tip 11 is away from the load is slightly increased, and decreases slightly when the time is reduced, but the operation is repeated at a stable speed. If there is no change, there will be no significant change, and as described above, the state will be such that repetition of a slight decrease at the time of contact with the load and a slight increase at the time of separation continues, centering on the level of 370 ° C. which has decreased by about 20 ° C.
[0068]
After the soldering operation of the 1/4 W carbon resistor, the soldering operation of the 2 W carbon resistor and immediately thereafter the 3 W carbon resistor is performed in the same manner, and as shown in FIG. Although the temperature drop increases with each mounting operation, the temperature is reduced by about 35 ° C. in the last 3 W carbon resistance soldering operation, and is not so large. The temperature change during the soldering operation is basically the same as the temperature change during the soldering operation of a 1/4 W carbon resistor. In addition, when the load is removed after the soldering operation is completed, the temperature rises rapidly in each case and returns to 390 ° C., but no particular overshoot occurs.
[0069]
As can be seen from the above results, according to the soldering iron of the fourth embodiment, practically sufficient durability can be ensured for the lead-free solder, and there is no problem in wettability. Further, during the soldering operation, a large overshoot does not occur immediately after leaving the load, and the temperature control is easy.
[0070]
【The invention's effect】
According to the soldering iron according to the first aspect of the present invention, in a soldering operation using lead-free solder, at least a portion of the tip of the tip that comes into contact with the solder is made of an iron-silicon alloy. Since it is constituted, it is possible to secure a long life that can be used for a long period without being easily eroded. Even with such a lead-free solder, the wettability is relatively good, and there is no problem in workability.
[0071]
According to the soldering iron of the second aspect of the present invention, it is needless to say that the soldering iron has the same effect as the soldering iron of the first aspect of the present invention. Since the heat transfer between the tip portion and the heat storage portion is performed well, the temperature drop at the tip portion of the tip during loading can be suppressed as much as possible, and the temperature rises sharply after the load ends (overshoot). This makes it possible to easily perform precise temperature control for suppressing the temperature.
[0072]
In addition, since the soldering iron tip 2 of the present invention has the above-described configuration, a rod-shaped member composed of an iron-silicon alloy core material and an outer peripheral portion of the heat storage part material has a length of the tip. To form a tip having a desired shape in which the iron-silicon alloy is exposed, and drilling a hole along the axis from the other end to form a cylindrical portion. And can be easily manufactured by inserting a heating means into the cylindrical portion.
[0073]
According to such a manufacturing method, the tip of the tip is formed of an iron-silicon alloy which is the core material of the rod-shaped member, and the heat storage portion on the outer peripheral side is formed of a heat storage material which is the outer peripheral portion of the rod-shaped member. Will be configured.
[0074]
If such a manufacturing method is adopted, the core portion of the tip of the iron tip is made of a solid material of iron-silicon alloy. The cord material composition is more stable than that of, and the life is long. Unlike the tip of a plated product, it can be ground or the like. In addition, it can be manufactured in a shorter time than the tip of a plated product.
[0075]
According to the soldering iron of the third aspect of the present invention, it is needless to say that the soldering iron has the same effect as the soldering iron of the first aspect of the present invention. Since the heat transfer between the tip portion and the heat storage portion is performed well, the temperature drop at the tip portion of the tip during loading can be suppressed as much as possible, and the temperature rises sharply after the load ends (overshoot). This makes it possible to easily perform precise temperature control for suppressing the temperature.
[0076]
According to the soldering iron tip of the fourth aspect of the present invention, in a soldering operation using lead-free solder, the soldering tip can be easily used for a long time without being eroded. Even with such a lead-free solder, the wettability is relatively good, and there is no problem in workability.
[0077]
According to the soldering iron according to the fifth aspect of the present invention, since the soldering iron has a sufficient heat storage capacity, the stored heat energy is quickly supplied to the tip of the soldering tip when a load is applied. This allows the temperature drop to be kept within allowable limits.
[Brief description of the drawings]
FIG. 1A is a longitudinal sectional view of a soldering iron tip according to a first embodiment.
(B) is a side view of the soldering iron tip of Example 1. FIG.
FIG. 2 is a graph showing a temperature change at a tip of a soldering iron tip when a soldering operation is performed using the soldering iron tip of the first embodiment.
FIG. 3 (a) is a longitudinal sectional view of a soldering iron of Examples 2, 3 and 4.
(B) is a side view of the soldering iron tips of Examples 2, 3, and 4.
(C) is a partially cutaway side view of a material optimal for manufacturing the soldering iron tips of Examples 2, 3, and 4.
FIG. 4 is a graph showing a temperature change at a tip of a soldering iron tip when a soldering operation is performed using the soldering iron tip of the second embodiment.
FIG. 5 is a graph showing a temperature change at a tip of a soldering iron tip when a soldering operation is performed using the soldering iron tip of the third embodiment.
FIG. 6 is a graph showing a temperature change at a tip of a soldering iron tip when a soldering operation is performed using the soldering iron tip of the fourth embodiment.
[Explanation of symbols]
1 Tip of tip
2 tubular part
3 Thermal storage unit
4 heater part (heating means)
5 Thermocouple
11 Tip of tip
11a Core at tip of tip
13 Thermal storage unit
14. Heater section (heating means)
15 Thermocouple
20 bar-shaped members
21 cylindrical core material
22 Outer circumference
D1 Outer diameter of cylindrical part
D2 Diameter of heat storage unit
D3 Outer diameter of core at tip of tip
D4 Outer diameter of heat storage unit
L1 Tip length
L2 Length of tip of iron tip
L3 Length of heat storage unit
L4 Tip length
L5 Length of tip of iron tip

Claims

A soldering iron tip in which at least a portion of the tip of the tip that comes into contact with the solder is made of an iron-silicon alloy.

The core portion of the tip of the tip is made of an iron-silicon alloy, heating means is arranged in series at the rear end, and the heat storage section extends from the middle to the end of the core portion of the tip of the tip. 2. The soldering iron tip according to claim 1, wherein said soldering iron is provided on a heating means arranged in series with said soldering iron.

The entire tip of the tip is made of an iron-silicon alloy, a tubular portion of the same material is extended from the outer edge of the rear end, a heat storage portion is provided inside the tubular portion, and the outer periphery of the tubular portion is provided. The soldering iron tip according to claim 1, further comprising a heating means.

4. A soldering iron according to claim 1, wherein the iron-silicon alloy has a silicon content of 0.3 to 1.0%.

4. The soldering iron tip according to claim 2, wherein said heat storage section is made of a copper material.