JP2004141937A - Surface coated au-sn alloy powder for solder paste - Google Patents
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Abstract
Description
【０００１】
【産業上の利用分野】
この発明は、はんだペーストを製造するために使用する表面被覆Ａｕ−Ｓｎ合金粉末に関するものである。
【０００２】
【従来の技術】
一般に、Ａｕ−Ｓｎ合金はんだペーストは、ＧａＡｓ光素子、ＧａＡｓ高周波素子、熱電素子などの半導体素子と基板との接合や微細かつ高気密性が要求されるＳＡＷフィルター、水晶発信子などの封止に使用されている。このＡｕ−Ｓｎ合金はんだペーストに含まれるＡｕ−Ｓｎ合金粉末は、Ｓｎ：１５〜２５質量％を含有し、残りがＡｕおよび不可避不純物からなる組成を有することが知られている。
【０００３】
このＡｕ−Ｓｎ合金はんだペーストに使用されるＡｕ−Ｓｎ合金粉末は、通常、Ａｕ−Ｓｎ合金を溶解して溶湯を作製し、温度：３００〜４００℃に保持し、この温度に保持された溶湯を自然落下させ、この自然落下する溶湯に周囲から不活性ガスを噴射して落下する溶湯に高圧不活性ガスを衝突させるガスアトマイズ法により製造する。かかる従来のガスアトマイズ法により得られたＡｕ−Ｓｎ合金粉末は平均粒径：１０〜１００μｍを有しているが、このガスアトマイズして得られたＡｕ−Ｓｎ合金粉末は表面が酸化されやすく、このＡｕ−Ｓｎ合金粉末の表面には一般に酸化膜が形成されている。この表面酸化膜を除去するためにロジン系のペースト化剤が使用されており、このＡｕ−Ｓｎ合金はんだペーストはＡｕ−Ｓｎ合金粉末にロジン系ペースト化剤と混合して製造している。
ところが、ロジン系ペースト化剤を混合したＡｕ−Ｓｎ合金はんだペーストは、ろう付け後にロジンの残渣が生じるために、これを洗浄で取り除かなければならず、洗浄行程を組み込めない前記ＧａＡｓ光素子、ＧａＡｓ高周波素子、熱電素子などの半導体素子と基板との接合には適用できない。
そのため、ロジンを含まないＡｕ−Ｓｎ合金はんだペーストが開発されており、流動パラフィン、テトラリン、ジエチルベンゼンを含むペースト化剤にＡｕ−Ｓｎ合金粉末：２〜２０質量％を添加した残渣の発生が極めて少ないＡｕ−Ｓｎ合金はんだペーストが開発されている（特許文献１参照）。
【０００４】
【特許文献１】
特開平６−２２６４８８号公報
【０００５】
【発明が解決しようとする課題】
しかし、Ａｕ−Ｓｎ合金粉末は製造後ただちにＡｕ−Ｓｎ合金はんだペーストの原料として使用されることは稀であり、通常は製造したのち一旦貯蔵され、必要に際して適宜取り出して使用される。そのために、ロジンを含まないペースト化剤を使用して作製したＡｕ−Ｓｎ合金はんだペーストはＡｕ−Ｓｎ合金粉末の表面に形成された表面酸化膜の除去が十分でないために、前記ロジンを含まないＡｕ−Ｓｎ合金はんだはロジンを含むペースト化剤を使用して作製したＡｕ−Ｓｎ合金はんだペーストに比べて十分な濡れ広がり性を確保することができなかった。そのため、ロジンを含まないペースト化剤を使用して洗浄工程を必要としない濡れ広がり性に優れたＡｕ−Ｓｎ合金はんだペーストの開発に迫られていた。
【０００６】
【課題を解決するための手段】
そこで、本発明者らは、濡れ広がり性に一層優れたロジンを含まないＡｕ−Ｓｎ合金はんだペーストを作製すべく研究を行った。その結果、
（ａ）Ａｕ−Ｓｎ合金粉末の表面に、貴金属（Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕ）からなる貴金属層を形成してＡｕ−Ｓｎ合金粉末の表面に形成される酸化膜の量を減らしたＡｕ−Ｓｎ合金粉末を作製し、この表面酸化膜の少ないＡｕ−Ｓｎ合金粉末をロジンを含まないペースト化剤と混合して得られたはんだペーストは、Ａｕ−Ｓｎ合金粉末がリフロー中に雰囲気から酸化されることを防ぐと共にロジンなどの活性成分を含まなくても十分な濡れ広がり性を実現できる、
（ｂ）その際、Ａｕ−Ｓｎ合金粉末の表面に形成される貴金属層の厚さは１０〜１０００ｎｍの範囲内にあることが好ましい、
（ｃ）Ａｕ−Ｓｎ合金粉末の表面に形成された極めて薄い貴金属層は加熱または長期間放置するとＡｕ−Ｓｎ合金粉末内部に拡散してＡｕ−Ｓｎ合金粉末の融点を上げるところから、Ａｕ−Ｓｎ合金粉末の表面にＦｅ、Ｃｒ、Ｎｉの内のいずれかの金属からなる拡散吸収防止層を形成し、この拡散吸収防止層の上に貴金属からなる貴金属層を形成すると、長時間保存しても貴金属層がＡｕ−Ｓｎ合金粉末に拡散吸収されることはなく、またろう付け加熱時に貴金属層がＡｕ−Ｓｎ合金粉末に拡散吸収されることを防止し、Ａｕ−Ｓｎ合金粉末の融点を上昇させることはない、
（ｄ）前記Ａｕ−Ｓｎ合金粉末の表面に形成される貴金属層または貴金属層および拡散吸収防止層からなる複合コーティング層は、それぞれＡｕ−Ｓｎ合金粉末の表面全面に形成されている必要はなく、Ａｕ−Ｓｎ合金粉末の表面の３０面積％以上に形成されていれば、その部分を起点として粉末の溶融が進み、はんだの濡れが問題なく達成される、という研究結果が得られたのである。
【０００７】
この発明は、かかる研究結果にもとづいてなされたものであって、
（１）Ｓｎ：１５〜２５質量％を含有し、残りがＡｕおよび不可避不純物からなる組成を有するＡｕ−Ｓｎ合金粉末の表面に、厚さ：１０〜１０００ｎｍを有するＡｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕの内のいずれかの貴金属からなる貴金属層を形成してなるはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、
（２）前記貴金属層は、Ａｕ−Ｓｎ合金粉末の表面の３０面積％以上に亘って形成されている（１）記載のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、
（３）Ｓｎ：１５〜２５質量％を含有し、残りがＡｕおよび不可避不純物からなる組成を有するＡｕ−Ｓｎ合金粉末の表面に、
厚さ：１０〜１０００ｎｍを有するＦｅ、Ｃｒ、Ｎｉの内のいずれかの金属からなる拡散吸収防止層と、この拡散吸収防止層の上に形成された厚さ：１０〜１０００ｎｍを有するＡｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕの内のいずれかの貴金属からなる貴金属層とからなる複合コーティング層を形成してなるはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、
（４）前記貴金属層および拡散吸収防止層からなる複合コーティング層は、Ａｕ−Ｓｎ合金粉末の表面の３０面積％以上に亘って形成されている（３）記載のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、に特徴を有するものである。
【０００８】
前記貴金属層は、貴金属（Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕ）を電解または無電解メッキにより形成したメッキ層であってもよく、貴金属粉末を凝集させた凝集粉末層であってもよく、また貴金属からなるターゲットを用いてスパッタリングして得られたスパッタリング層であってもよい。したがって、この発明は、
（５）前記貴金属層は、Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕの内のいずれかの貴金属を電解メッキして得られた電解メッキ層である前記（１）、（２）、（３）または（４）記載のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、
（６）前記貴金属層は、Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕの内のいずれかの貴金属からなるターゲットを用いてスパッタリングして得られたスパッタリング層である（１）、（２）、（３）または（４）記載のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、
（７）前記貴金属層は、Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕの内のいずれかの貴金属粉末を凝集させた凝集粉末層である前記（１）、（２）、（３）または（４）記載のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末、に特徴を有するものである。
【０００９】
Ｓｎ：１５〜２５質量％を含有し、残りがＡｕおよび不可避不純物からなる組成を有するＡｕ−Ｓｎ合金は、Ａｕ−Ｓｎはんだ合金として最も広く用いられており、その成分組成も既に知られているので、その成分組成範囲の限定理由の説明は省略する。また、この発明のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末は、通常のアトマイズ法により作製したＡｕ−Ｓｎ合金粉末を使用し、その平均粒径は１０〜１００μｍの範囲内にあり、この平均粒径は市販のＡｕ−Ｓｎ合金粉末の平均粒径と同じである。
【００１０】
かかる通常のＡｕ−Ｓｎ合金粉末の表面に形成される貴金属（Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕ）からなる貴金属層は、その厚さが１０ｎｍ未満ではＡｕ−Ｓｎ合金粉末溶融時に瞬時に溶融したＡｕ−Ｓｎ合金に吸収されて十分な効果が得られず、一方、１０００ｎｍを越えると、Ａｕ−Ｓｎ合金の組成の変動が大きくなり、融点が大きく変化し、それによって濡れ広がり性に悪影響を与えるので好ましくない。したがって、Ａｕ−Ｓｎ合金粉末の表面に形成される貴金属層の厚さは１０〜１０００ｎｍに定めた。貴金属層の厚さの一層好ましい範囲は電解メッキ層の場合は２００〜５００ｎｍ、スッパッタリング層の場合は１００〜５００ｎｍ、凝集粉末層の場合は３００〜７００ｎｍである。
【００１１】
また、この発明のＡｕ−Ｓｎ合金粉末の表面に形成されるＦｅ、Ｃｒ、Ｎｉの内のいずれかの金属からなる拡散吸収防止層は必要に応じて形成されるが、その厚さが１０ｎｍ未満では貴金属からなる貴金属層の拡散に対するバリア効果が薄いので好ましくなく、一方、１０００ｎｍを越えると、Ａｕ−Ｓｎ合金に不純物として取り込まれ、組成の変動が大きくなり、融点が大きく変化して濡れ広がり性に悪影響を与えるので好ましくない。したがって、Ａｕ−Ｓｎ合金粉末の表面に形成される拡散吸収防止層の厚さは１０〜１０００ｎｍに定めた。拡散吸収防止層の厚さの一層好ましい範囲は５０〜５００ｎｍである。
【００１２】
また、この発明のＡｕ−Ｓｎ合金粉末の表面に形成される貴金属（Ａｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕ）からなる貴金属層は、Ａｕ−Ｓｎ合金粉末の表面全面に形成されることが最も好ましいが、表面全面に形成されなくても所定の効果が得られ、その被覆率は３０％未満になると十分な効果が得られないので、Ａｕ−Ｓｎ合金粉末の表面に形成される貴金属層の被覆率は３０％以上に定めた。さらに拡散吸収防止層の被覆率は３０％未満になると、十分な効果が得られないので、Ａｕ−Ｓｎ合金粉末の表面に形成される拡散吸収防止層の被覆率は３０％以上に定めた。
【００１３】
【発明の実施の形態】
Ｓｎ：２０質量％を含有し、残部がＡｕおよび不可避不純物からなる成分組成を有し、平均粒径：２０μｍを有する市販のガスアトマイズＡｕ−Ｓｎ合金粉末を従来Ａｕ−Ｓｎ合金粉末として用意した。
【００１４】
実施例１
このＡｕ−Ｓｎ合金粉末に対し、シアン化第一金カリウムを水に溶解し、クエン酸を加えてＰＨを約５に調整した浴を用いて無電解メッキによりＡｕ−Ｓｎ合金粉末の表面全面に表１に示される厚さのＡｕからなる貴金属層を形成し、本発明はんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末（以下、本発明表面被覆Ａｕ−Ｓｎ合金粉末という）１〜５および比較はんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末（以下、比較表面被覆Ａｕ−Ｓｎ合金粉末という）１〜２を作製した。なお、Ａｕからなる貴金属層の厚さは無電解メッキ時間を調整することにより調節した。
かかる本発明表面被覆Ａｕ−Ｓｎ合金粉末１〜５、比較表面被覆Ａｕ−Ｓｎ合金粉末１〜２および先に用意した従来Ａｕ−Ｓｎ合金粉末のそれぞれに対し、流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金について、光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表１に示した。なお、表面光沢の有無は溶融はんだ部分における反射率を測定し、５０％以上の反射率を表面光沢「有」、５０％未満の反射率を表面光沢「無」として評価した。
【００１５】
【表１】
表１に示される結果から、本発明表面被覆Ａｕ−Ｓｎ合金粉末１〜５を含むはんだペーストは、従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末１〜２を含むはんだペーストは好ましくない特性があることがわかる。
【００１７】
実施例２
撹拌機構とメッシュ状のアノード及びカソードを備えたメッキ装置を用意し、市販のメッキ液（日本エレクトロプレイティング・エンジニヤース製のパラデックスＭＳ（商品名））を用い、このメッキ液中にＡｕ−Ｓｎ合金粉末を撹拌・分散しながら、電流密度：２Ａ／ｄｍ２、メッキ浴温度：６０℃で電解メッキ時間を変えることにより電解メッキを行い、Ａｕ−Ｓｎ合金粉末に表２に示される厚さのＰｄからなる貴金属層を形成することにより本発明表面被覆Ａｕ−Ｓｎ合金粉末６〜１０および比較表面被覆Ａｕ−Ｓｎ合金粉末３〜４を作製した。なお、Ｐｄからなる貴金属層の厚さは電解メッキ時間を調整することにより調節した。
かかる本発明表面被覆Ａｕ−Ｓｎ合金粉末６〜１０および比較表面被覆Ａｕ−Ｓｎ合金粉末３〜４のそれぞれに対し、流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表２に示した。
【００１８】
【表２】
表２に示される結果から、本発明表面被覆Ａｕ−Ｓｎ合金粉末６〜１０を含むはんだペーストは、表１の従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末３〜４を含むはんだペーストは好ましくない特性があることがわかる。
【００２０】
実施例３
撹拌機構とメッシュ状のアノード及びカソードを備えたメッキ装置を用意し、市販のメッキ液（日本エレクトロプレイティング・エンジニヤース製のスーパーロジウムＮｏ１（商品名））を用い、このメッキ液中にＡｕ−Ｓｎ合金粉末を撹拌・分散しながら、電流密度：１．３４Ａ／ｄｍ２、メッキ浴温度：５０℃で電解メッキ時間を変えることにより電解メッキを行い、Ａｕ−Ｓｎ合金粉末に表３に示される厚さのＲｈからなる貴金属層を形成し、本発明表面被覆Ａｕ−Ｓｎ合金粉末１１〜１５および比較表面被覆Ａｕ−Ｓｎ合金粉末５〜６を作製した。なお、Ｒｈからなる貴金属層の厚さは電解メッキ時間を調整することにより調節した。
かかる本発明表面被覆Ａｕ−Ｓｎ合金粉末１１〜１５および比較表面被覆Ａｕ−Ｓｎ合金粉末５〜６に対し、それぞれ流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表３に示した。
【００２１】
【表３】
表３に示される結果から、本発明表面被覆Ａｕ−Ｓｎ合金粉末１１〜１５を含むはんだペーストは、表１の従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末５〜６を含むはんだペーストは好ましくない特性があることがわかる。
【００２３】
実施例４
撹拌機構とメッシュ状のアノード及びカソードを備えたメッキ装置を用意し、市販のメッキ液（日本エレクトロプレイティング・エンジニヤース製のプラタネクス３ＬＳ（商品名））を用い、このメッキ液中にＡｕ−Ｓｎ合金粉末を撹拌・分散しながら、電流密度：２Ａ／ｄｍ２、メッキ浴温度：８０℃で電解メッキ時間を変えることにより電解メッキを行い、Ａｕ−Ｓｎ合金粉末に表４に示される厚さのＰｔからなる貴金属層を形成し、本発明表面被覆Ａｕ−Ｓｎ合金粉末１６〜２０および比較表面被覆Ａｕ−Ｓｎ合金粉末７〜８を作製した。なお、Ｐｔからなる貴金属層の厚さは電解メッキ時間を調整することにより調節した。
かかる本発明表面被覆Ａｕ−Ｓｎ合金粉末１６〜２０および比較表面被覆Ａｕ−Ｓｎ合金粉末７〜８に対し、それぞれ流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表４に示した。
【００２４】
【表４】
表４に示される結果から、本発明表面被覆Ａｕ−Ｓｎ合金粉末１６〜２０を含むはんだペーストは、表１の従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末７〜８を含むはんだペーストは好ましくない特性があることがわかる。
【００２６】
実施例５
撹拌機構とメッシュ状のアノード及びカソードを備えたメッキ装置を用意し、市販のメッキ液（日本エレクトロプレイティング・エンジニヤース製のルテネックス（商品名））を用い、このメッキ液中にＡｕ−Ｓｎ合金粉末を撹拌・分散しながら、電流密度：１Ａ／ｄｍ２、メッキ浴温度：６５℃で電解メッキ時間を変えることにより電解メッキを行い、Ａｕ−Ｓｎ合金粉末に表５に示される厚さのＲｕからなる貴金属層を形成し、本発明表面被覆Ａｕ−Ｓｎ合金粉末２１〜２５および比較表面被覆Ａｕ−Ｓｎ合金粉末９〜１０を作製した。なお、Ｒｕからなる貴金属層の厚さは電解メッキ時間を調整することにより調節した。
かかる本発明表面被覆Ａｕ−Ｓｎ合金粉末２１〜２５および比較表面被覆Ａｕ−Ｓｎ合金粉末９〜１０に対し、それぞれ流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表５に示した。
【００２７】
【表５】
表５に示される結果から、本発明表面被覆Ａｕ−Ｓｎ合金粉末２１〜２５を含むはんだペーストは、表１の従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末９〜１０を含むはんだペーストは好ましくない特性があることがわかる。
【００２９】
実施例６
直流マグネトロンスパッタリング装置を用意し、この装置に金ターゲットをセットし、一方、先に用意したガスアトマイズＡｕ−Ｓｎ合金粉末を金ターゲットの下方に位置するトレイに薄く広げ、さらにトレイを自転させて均一にコーティングすることにより厚さ：５０ｎｍのＡｕからなる貴金属層を形成した本発明表面被覆Ａｕ−Ｓｎ合金粉末２６〜３０および比較表面被覆Ａｕ−Ｓｎ合金粉末１１〜１２を作製した。この場合、コーティングされるのは粉末のターゲット方向を向いている面のみであるが、ＳＥＭ観察によりＡｕ−Ｓｎ合金粉末表面の貴金属層の被覆率を測定した。得られた本発明表面被覆Ａｕ−Ｓｎ合金粉末２６〜３０および比較表面被覆Ａｕ−Ｓｎ合金粉末１１〜１２に対し、それぞれ流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表６に示した。
【００３０】
【表６】
表６に示される結果から、貴金属層の被覆率が３０面積％以上の本発明表面被覆Ａｕ−Ｓｎ合金粉末２６〜３０を含むはんだペーストは、表１に示される従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、貴金属層の被覆率が３０面積％未満のこの発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末１１〜１２を含むはんだペーストは、はんだ広がり率が十分でないことがわかる。
【００３２】
実施例７
先に用意した平均粒径：２０μｍを有する市販のガスアトマイズＡｕ−Ｓｎ合金粉末と、市販の超微粒Ａｕ粉末（平均粒径：０．０１μｍ）を質量被４０：１の割合でヘキサン溶媒をとしてボールミルにより１２時間混合した。混合後、得られた混合粉末をＳＥＭで観察したところ、超微粒Ａｕ粉末がガスアトマイズＡｕ−Ｓｎ合金粉末の表面を、表７に示される厚さを有する超微粒Ａｕ粉末が凝集してなる凝集粉末層が形成された本発明表面被覆Ａｕ−Ｓｎ合金粉末３１〜３５および比較表面被覆Ａｕ−Ｓｎ合金粉末１３〜１４が得られた。これら本発明表面被覆Ａｕ−Ｓｎ合金粉末３１〜３５および比較表面被覆Ａｕ−Ｓｎ合金粉末１３〜１４に対し、それぞれ流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。
これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表７に示した。
【００３３】
【表７】
表７に示される結果から、貴金属層の被覆率が３０面積％以上の本発明表面被覆Ａｕ−Ｓｎ合金粉末３１〜３５を含むはんだペーストは、表１に示される従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末１３〜１４を含むはんだペーストは、はんだ広がり率が十分でないことがわかる。
【００３５】
実施例８
直流マグネトロンスパッタリング装置を用意し、この装置にまずＮｉターゲットをセットし、一方、先に用意したガスアトマイズＡｕ−Ｓｎ合金粉末を金ターゲットの下方に位置するトレイに薄く広げ、さらにトレイを自転させて均一にコーティングすることにより厚さ：５０ｎｍのＮｉからなる拡散吸収防止層を形成した。
引き続いて、同じ直流マグネトロンスパッタリング装置にＡｕターゲットをセットし、厚さ：５０ｎｍのＮｉからなる拡散吸収防止層を形成したガスアトマイズＡｕ−Ｓｎ合金粉末の上に、さらにＡｕからなる貴金属層を形成し、Ｎｉ層およびＡｕ層からなる複合コーティング層を形成することにより本発明表面被覆Ａｕ−Ｓｎ合金粉末３６〜４０および比較表面被覆Ａｕ−Ｓｎ合金粉末１５〜１６を作製した。この場合、コーティングされるのは粉末のターゲット方向を向いている面のみであるが、ＳＥＭ観察によりＡｕ−Ｓｎ合金粉末表面のＮｉ層およびＡｕ層の被覆率も測定した。得られた本発明表面被覆Ａｕ−Ｓｎ合金粉末３６〜４０および比較表面被覆Ａｕ−Ｓｎ合金粉末１５〜１６に対し、それぞれ流動パラフィン：２．４質量％、パラフィンワックス２．６質量％を添加し混合し、加熱溶解してはんだペーストを作製した。これらはんだペーストを用い、ＪＩＳ Ｚ ３１９７で規定される方法にしたがってはんだ広がり率を測定し、また同時に溶融後のＡｕ−Ｓｎ合金はんだについて、実施例１と同様にして光学顕微鏡によりＡｕ−Ｓｎ合金粉末が解けずに残る未溶融部分の有無を観察し、さらに表面光沢の有無を観察し、その結果を表８に示した。
【００３６】
【表８】
表８に示される結果から、本発明表面被覆Ａｕ−Ｓｎ合金粉末３６〜４０を含むはんだペーストは、表１に示される従来Ａｕ−Ｓｎ合金粉末を含むはんだペーストに比べてはんだ広がり率が大きいことがわかる。しかし、この発明の範囲から外れた比較表面被覆Ａｕ−Ｓｎ合金粉末１５〜１６を含むはんだペーストは、はんだ広がり率が十分でないことがわかる。
【００３８】
【発明の効果】
上述のように、この発明のはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末は、ロジンを含まないペースト化剤に添加しても、従来のはんだペーストに比べて濡れ広がり性に優れ、しかもロジンを含まないのでろう付け後の残渣の発生が少なく、ろう付け後の洗浄工程を省略することが出来、しかも良好なはんだ付けを行うことが出来るのでコストを低減することができ、産業上優れた効果をもたらすものである。[0001]
[Industrial applications]
The present invention relates to a surface-coated Au-Sn alloy powder used for producing a solder paste.
[0002]
[Prior art]
In general, Au-Sn alloy solder paste is used for bonding semiconductor devices such as GaAs optical devices, GaAs high-frequency devices, and thermoelectric devices to substrates, and for sealing SAW filters and quartz oscillators that require fine and high airtightness. It is used. It is known that the Au-Sn alloy powder contained in this Au-Sn alloy solder paste contains Sn: 15 to 25% by mass, and the remainder has a composition of Au and unavoidable impurities.
[0003]
The Au-Sn alloy powder used in the Au-Sn alloy solder paste is usually prepared by melting an Au-Sn alloy to prepare a molten metal, and maintaining the temperature at 300 to 400 ° C. Is spontaneously dropped, and an inert gas is injected from the surroundings into the molten metal that falls naturally to produce a molten metal by a gas atomization method in which high-pressure inert gas collides with the molten metal. The Au-Sn alloy powder obtained by the conventional gas atomization method has an average particle diameter of 10 to 100 µm. However, the surface of the Au-Sn alloy powder obtained by gas atomization is easily oxidized, Generally, an oxide film is formed on the surface of the -Sn alloy powder. A rosin-based paste agent is used to remove the surface oxide film, and the Au-Sn alloy solder paste is manufactured by mixing an Au-Sn alloy powder with a rosin-based paste agent.
However, the Au-Sn alloy solder paste mixed with the rosin-based paste agent has a rosin residue after brazing, and therefore must be removed by cleaning, and the GaAs optical element, GaAs, which cannot incorporate a cleaning step. It cannot be applied to bonding between a semiconductor element such as a high-frequency element or a thermoelectric element and a substrate.
Therefore, an Au-Sn alloy solder paste containing no rosin has been developed, and the generation of a residue obtained by adding 2 to 20% by mass of an Au-Sn alloy powder to a paste agent containing liquid paraffin, tetralin, and diethylbenzene is extremely low. Au-Sn alloy solder paste has been developed (see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-6-226488 [0005]
[Problems to be solved by the invention]
However, the Au-Sn alloy powder is rarely used as a raw material of the Au-Sn alloy solder paste immediately after production, and is usually stored once after production, and is taken out as needed when necessary. Therefore, the Au-Sn alloy solder paste prepared using a rosin-free paste agent does not include the rosin because the surface oxide film formed on the surface of the Au-Sn alloy powder is not sufficiently removed. The Au—Sn alloy solder could not secure sufficient wettability and spreadability as compared with the Au—Sn alloy solder paste produced using a rosin-containing paste agent. Therefore, there has been an urgent need to develop an Au—Sn alloy solder paste that uses a rosin-free paste agent and does not require a cleaning step and has excellent wet spreadability.
[0006]
[Means for Solving the Problems]
Then, the present inventors have studied to produce an Au—Sn alloy solder paste containing no rosin, which is more excellent in wet spreadability. as a result,
(A) A noble metal layer made of a noble metal (Au, Pt, Rh, Pd, Ru) is formed on the surface of the Au-Sn alloy powder to reduce the amount of an oxide film formed on the surface of the Au-Sn alloy powder. A solder paste obtained by preparing an Au-Sn alloy powder and mixing the Au-Sn alloy powder having a small surface oxide film with a rosin-free paste agent is obtained from the atmosphere during the reflow of the Au-Sn alloy powder. Prevents oxidation and can achieve sufficient wetting and spreading even without containing active ingredients such as rosin.
(B) At that time, the thickness of the noble metal layer formed on the surface of the Au—Sn alloy powder is preferably in the range of 10 to 1000 nm.
(C) The extremely thin noble metal layer formed on the surface of the Au—Sn alloy powder diffuses into the Au—Sn alloy powder when heated or left for a long period of time and raises the melting point of the Au—Sn alloy powder. When a diffusion prevention layer made of any one of Fe, Cr and Ni is formed on the surface of the alloy powder and a noble metal layer made of a noble metal is formed on this diffusion prevention layer, The noble metal layer is not diffused and absorbed in the Au-Sn alloy powder, and prevents the noble metal layer from being diffused and absorbed in the Au-Sn alloy powder during brazing heating, thereby increasing the melting point of the Au-Sn alloy powder. Never
(D) The noble metal layer formed on the surface of the Au—Sn alloy powder or the composite coating layer composed of the noble metal layer and the diffusion-absorption preventing layer need not be formed on the entire surface of the Au—Sn alloy powder, respectively. Research results have shown that if formed at 30% by area or more of the surface of the Au-Sn alloy powder, the melting of the powder proceeds from that portion as a starting point, and solder wetting can be achieved without any problem.
[0007]
The present invention has been made based on the results of such research,
(1) Sn: Au, Pt, Rh, Pd, having a thickness of 10 to 1000 nm on the surface of an Au—Sn alloy powder having a composition of 15 to 25% by mass and a balance of Au and unavoidable impurities. A surface-coated Au-Sn alloy powder for a solder paste formed by forming a noble metal layer made of any one of Ru.
(2) The surface-coated Au-Sn alloy powder for a solder paste according to (1), wherein the noble metal layer is formed over 30% by area or more of the surface of the Au-Sn alloy powder.
(3) Sn: 15 to 25% by mass of Au—Sn alloy powder having a composition consisting of Au and inevitable impurities,
A diffusion / absorption prevention layer made of any one of Fe, Cr and Ni having a thickness of 10 to 1000 nm, and Au and Pt having a thickness of 10 to 1000 nm formed on the diffusion / absorption prevention layer , Rh, Pd, and Ru, a surface-coated Au-Sn alloy powder for a solder paste formed by forming a composite coating layer composed of a noble metal layer made of a noble metal,
(4) The surface coating Au-Sn for a solder paste according to (3), wherein the composite coating layer comprising the noble metal layer and the diffusion-absorption preventing layer is formed over 30% by area or more of the surface of the Au-Sn alloy powder. Alloy powder.
[0008]
The noble metal layer may be a plating layer formed by electrolytic or electroless plating of a noble metal (Au, Pt, Rh, Pd, Ru), or may be an agglomerated powder layer in which a noble metal powder is agglomerated. It may be a sputtering layer obtained by sputtering using a target made of a noble metal. Therefore, the present invention
(5) The above-mentioned (1), (2), (3) or (3), wherein the noble metal layer is an electroplated layer obtained by electroplating any one of Au, Pt, Rh, Pd, and Ru. (4) The surface-coated Au-Sn alloy powder for a solder paste according to (4),
(6) The noble metal layer is a sputtering layer obtained by sputtering using a target made of any one of Au, Pt, Rh, Pd, and Ru. (1), (2), (3) )) Or surface-coated Au-Sn alloy powder for a solder paste according to (4),
(7) The noble metal layer is an agglomerated powder layer formed by aggregating any noble metal powder of Au, Pt, Rh, Pd, and Ru. (1), (2), (3) or (4) The surface-coated Au-Sn alloy powder for a solder paste described above has characteristics.
[0009]
An Au-Sn alloy containing 15 to 25% by mass of Sn and having a balance of Au and unavoidable impurities is most widely used as an Au-Sn solder alloy, and its component composition is already known. Therefore, description of the reason for limiting the component composition range is omitted. The surface-coated Au-Sn alloy powder for a solder paste of the present invention uses Au-Sn alloy powder produced by a normal atomizing method, and has an average particle size in a range of 10 to 100 µm. The diameter is the same as the average particle diameter of a commercially available Au-Sn alloy powder.
[0010]
When the thickness of the noble metal layer (Au, Pt, Rh, Pd, Ru) formed on the surface of the normal Au-Sn alloy powder is less than 10 nm, the noble metal layer is instantaneously melted when the Au-Sn alloy powder is melted. Absorbed by the Au-Sn alloy, a sufficient effect cannot be obtained. On the other hand, if it exceeds 1000 nm, the composition of the Au-Sn alloy fluctuates greatly, the melting point greatly changes, thereby adversely affecting the wet spreadability. It is not preferred. Therefore, the thickness of the noble metal layer formed on the surface of the Au—Sn alloy powder is set to 10 to 1000 nm. A more preferable range of the thickness of the noble metal layer is 200 to 500 nm for the electrolytic plating layer, 100 to 500 nm for the sputtering layer, and 300 to 700 nm for the aggregated powder layer.
[0011]
The diffusion / absorption prevention layer made of any one of Fe, Cr, and Ni formed on the surface of the Au—Sn alloy powder of the present invention is formed as necessary, but has a thickness of less than 10 nm. Is not preferable because the barrier effect against diffusion of the noble metal layer made of a noble metal is thin. On the other hand, if it exceeds 1000 nm, it is taken in as an impurity in the Au—Sn alloy, the composition fluctuates greatly, the melting point changes greatly, and the wet It is not preferable because it adversely affects the performance. Therefore, the thickness of the diffusion-absorption preventing layer formed on the surface of the Au—Sn alloy powder is set to 10 to 1000 nm. A more preferred range for the thickness of the diffusion absorption preventing layer is 50 to 500 nm.
[0012]
The noble metal layer made of a noble metal (Au, Pt, Rh, Pd, Ru) formed on the surface of the Au—Sn alloy powder of the present invention is most preferably formed on the entire surface of the Au—Sn alloy powder. However, a predetermined effect can be obtained even if it is not formed on the entire surface, and if the coverage is less than 30%, a sufficient effect cannot be obtained. Therefore, the coating of the noble metal layer formed on the surface of the Au—Sn alloy powder The rate was set to 30% or more. Further, if the coverage of the diffusion / absorption prevention layer is less than 30%, a sufficient effect cannot be obtained. Therefore, the coverage of the diffusion / absorption prevention layer formed on the surface of the Au—Sn alloy powder is set to 30% or more.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
A commercially available gas atomized Au-Sn alloy powder containing 20% by mass of Sn, the balance having a composition of Au and unavoidable impurities, and having an average particle diameter of 20 µm was prepared as a conventional Au-Sn alloy powder.
[0014]
Example 1
To this Au-Sn alloy powder, gold (II) cyanide was dissolved in water, and citric acid was added to adjust the pH to about 5 by electroless plating on the entire surface of the Au-Sn alloy powder. A noble metal layer made of Au having a thickness shown in Table 1 was formed, and a surface-coated Au-Sn alloy powder for a solder paste of the present invention (hereinafter, referred to as a surface-coated Au-Sn alloy powder of the present invention) 1 to 5 and a comparative solder paste Surface-coated Au-Sn alloy powders (hereinafter referred to as comparative surface-coated Au-Sn alloy powders) 1 and 2 were prepared. The thickness of the noble metal layer made of Au was adjusted by adjusting the electroless plating time.
Liquid paraffin: 2.4% by mass for each of the surface-coated Au-Sn alloy powders 1 to 5 of the present invention, the comparative surface-coated Au-Sn alloy powders 1 and 2, and the previously prepared conventional Au-Sn alloy powder. 2.6 mass% of paraffin wax was added, mixed, and dissolved by heating to prepare a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197, and at the same time, the unmelted portion of the Au-Sn alloy after melting without remaining unmelted by an optical microscope was observed using an optical microscope. Was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 1. The presence or absence of surface gloss was measured by measuring the reflectance at the molten solder portion, and the reflectance of 50% or more was evaluated as “presence”, and the reflectance of less than 50% was evaluated as “absence”.
[0015]
[Table 1]
From the results shown in Table 1, it can be seen that the solder paste containing the surface-coated Au-Sn alloy powders 1 to 5 of the present invention has a larger solder spread ratio than the solder paste containing the conventional Au-Sn alloy powder. However, it can be seen that the solder paste containing the comparative surface-coated Au-Sn alloy powders 1 and 2 which is out of the range of the present invention has unfavorable characteristics.
[0017]
Example 2
A plating apparatus having a stirring mechanism and a mesh-shaped anode and cathode was prepared, and a commercially available plating solution (Paradex MS (trade name) manufactured by Nippon Electroplating Engineers) was used. Electroplating was performed by changing the electroplating time at a current density of 2 A / dm 2 and a plating bath temperature of 60 ° C. while stirring and dispersing the Sn alloy powder, and the Au-Sn alloy powder had a thickness shown in Table 2 By forming a noble metal layer made of Pd, surface-coated Au-Sn alloy powders 6 to 10 of the present invention and comparative surface-coated Au-Sn alloy powders 3 to 4 were produced. The thickness of the noble metal layer made of Pd was adjusted by adjusting the electrolytic plating time.
Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax are added and mixed to each of the surface-coated Au-Sn alloy powders 6 to 10 of the present invention and the comparative surface-coated Au-Sn alloy powders 3 to 4. Then, it was heated and melted to produce a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of the unmelted portion remaining without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 2.
[0018]
[Table 2]
From the results shown in Table 2, it can be seen that the solder paste containing the surface-coated Au-Sn alloy powders 6 to 10 of the present invention has a larger solder spread ratio than the solder paste containing the conventional Au-Sn alloy powder shown in Table 1. . However, it can be seen that the solder paste containing the comparative surface-coated Au-Sn alloy powders 3 and 4 which is out of the range of the present invention has unfavorable characteristics.
[0020]
Example 3
A plating apparatus having a stirring mechanism and a meshed anode and cathode was prepared, and a commercially available plating solution (Super Rhodium No. 1 (trade name) manufactured by Nippon Electroplating Engineers) was used. Electroplating was performed by changing the electroplating time at a current density of 1.34 A / dm 2 and a plating bath temperature of 50 ° C. while stirring and dispersing the Sn alloy powder, and the Au-Sn alloy powder is shown in Table 3. A noble metal layer made of Rh having a thickness was formed, and surface-coated Au-Sn alloy powders 11 to 15 of the present invention and comparative surface-coated Au-Sn alloy powders 5 to 6 were produced. The thickness of the noble metal layer made of Rh was adjusted by adjusting the electrolytic plating time.
Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax were added to and mixed with the surface-coated Au-Sn alloy powders 11 to 15 of the present invention and the comparative surface-coated Au-Sn alloy powders 5 to 6, respectively. Then, it was heated and melted to produce a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of unmelted portions that remained without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 3.
[0021]
[Table 3]
From the results shown in Table 3, it can be understood that the solder paste containing the surface-coated Au-Sn alloy powders 11 to 15 of the present invention has a larger solder spread ratio than the solder paste containing the conventional Au-Sn alloy powder shown in Table 1. . However, it can be seen that the solder paste containing the comparative surface-coated Au-Sn alloy powders 5 to 6 out of the range of the present invention has unfavorable characteristics.
[0023]
Example 4
A plating apparatus having a stirring mechanism and a mesh-shaped anode and cathode was prepared, and a commercially available plating solution (Platanex 3LS (trade name) manufactured by Nippon Electroplating Engineers) was used. While stirring and dispersing the alloy powder, electrolytic plating was performed by changing the electrolytic plating time at a current density of 2 A / dm 2 and a plating bath temperature of 80 ° C., and the Au—Sn alloy powder having a thickness shown in Table 4 was obtained. A noble metal layer made of Pt was formed, and surface-coated Au-Sn alloy powders 16 to 20 of the present invention and comparative surface-coated Au-Sn alloy powders 7 to 8 were produced. The thickness of the noble metal layer made of Pt was adjusted by adjusting the electrolytic plating time.
Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax were added to and mixed with the surface-coated Au-Sn alloy powders 16 to 20 of the present invention and the comparative surface-coated Au-Sn alloy powders 7 to 8, respectively. Then, it was heated and melted to produce a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of unmelted portions remaining without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 4.
[0024]
[Table 4]
From the results shown in Table 4, it can be seen that the solder paste containing the surface-coated Au-Sn alloy powders 16 to 20 of the present invention has a larger solder spread ratio than the solder paste containing the conventional Au-Sn alloy powder shown in Table 1. . However, it can be seen that the solder paste containing the comparative surface-coated Au-Sn alloy powders 7 to 8 out of the range of the present invention has unfavorable characteristics.
[0026]
Example 5
A plating apparatus equipped with a stirring mechanism and a mesh-shaped anode and cathode was prepared, and a commercially available plating solution (Lutenex (trade name) manufactured by Nippon Electroplating Engineers) was used. While stirring and dispersing the powder, electrolytic plating was performed by changing the electrolytic plating time at a current density of 1 A / dm 2 and a plating bath temperature of 65 ° C., and the Au—Sn alloy powder had a Ru having a thickness shown in Table 5. Was formed, and surface-coated Au-Sn alloy powders 21 to 25 of the present invention and comparative surface-coated Au-Sn alloy powders 9 to 10 were produced. Note that the thickness of the noble metal layer made of Ru was adjusted by adjusting the electrolytic plating time.
Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax are added and mixed to the surface-coated Au-Sn alloy powders 21 to 25 of the present invention and the comparative surface-coated Au-Sn alloy powders 9 to 10, respectively. Then, it was heated and melted to produce a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of unmelted portions that remained without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 5.
[0027]
[Table 5]
From the results shown in Table 5, it can be seen that the solder paste containing the surface-coated Au-Sn alloy powders 21 to 25 of the present invention has a larger solder spread ratio than the solder paste containing the conventional Au-Sn alloy powder shown in Table 1. . However, it can be seen that the solder paste containing the comparative surface-coated Au-Sn alloy powders 9 to 10 out of the range of the present invention has unfavorable characteristics.
[0029]
Example 6
Prepare a DC magnetron sputtering device, set a gold target in this device, while spreading the previously prepared gas atomized Au-Sn alloy powder thinly on a tray located below the gold target, and further rotate the tray to make it uniform The surface-coated Au-Sn alloy powders 26 to 30 of the present invention and the comparative surface-coated Au-Sn alloy powders 11 to 12 in which a noble metal layer made of Au having a thickness of 50 nm was formed by coating were prepared. In this case, only the surface facing the target direction of the powder was coated, but the coverage of the noble metal layer on the surface of the Au—Sn alloy powder was measured by SEM observation. Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax were added to the obtained surface-coated Au-Sn alloy powders 26 to 30 of the present invention and the comparative surface-coated Au-Sn alloy powders 11 to 12, respectively. The mixture was mixed and dissolved by heating to produce a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of unmelted portions remaining without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 6.
[0030]
[Table 6]
From the results shown in Table 6, the solder paste containing the surface-coated Au-Sn alloy powders 26 to 30 of the present invention in which the coverage of the noble metal layer is 30 area% or more includes the conventional Au-Sn alloy powder shown in Table 1. It can be seen that the solder spread rate is larger than that of the solder paste. However, it can be understood that the solder paste containing the comparative surface-coated Au-Sn alloy powders 11 to 12 having a noble metal layer coverage of less than 30 area% out of the range of the present invention has insufficient solder spread.
[0032]
Example 7
A commercially available gas atomized Au-Sn alloy powder having an average particle diameter of 20 μm prepared above and a commercially available ultrafine Au powder (average particle diameter: 0.01 μm) were mixed with a hexane solvent at a mass ratio of 40: 1 using a ball mill. For 12 hours. After mixing, the obtained mixed powder was observed with a SEM. As a result, the ultrafine Au powder was agglomerated powder obtained by aggregating the surface of the gas atomized Au-Sn alloy powder with the ultrafine Au powder having the thickness shown in Table 7. The surface-coated Au-Sn alloy powders 31 to 35 of the present invention and the comparative surface-coated Au-Sn alloy powders 13 to 14 on which layers were formed were obtained. Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax are added and mixed to the surface-coated Au-Sn alloy powders 31 to 35 of the present invention and the comparative surface-coated Au-Sn alloy powders 13 to 14, respectively. Then, it was heated and melted to produce a solder paste.
Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of unmelted portions remaining without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 7.
[0033]
[Table 7]
From the results shown in Table 7, the solder paste containing the surface-coated Au-Sn alloy powders 31 to 35 of the present invention in which the coverage of the noble metal layer is 30 area% or more includes the conventional Au-Sn alloy powder shown in Table 1. It can be seen that the solder spread rate is larger than that of the solder paste. However, it can be seen that the solder paste containing the comparative surface-coated Au-Sn alloy powders 13 to 14 out of the range of the present invention has insufficient solder spread rate.
[0035]
Example 8
Prepare a DC magnetron sputtering device, first set a Ni target in this device, while spreading the previously prepared gas atomized Au-Sn alloy powder thinly on a tray located below the gold target, and further rotate the tray to make it uniform. To form a diffusion / absorption prevention layer made of Ni having a thickness of 50 nm.
Subsequently, an Au target was set in the same DC magnetron sputtering apparatus, and a noble metal layer made of Au was further formed on the gas atomized Au-Sn alloy powder on which a diffusion absorption preventing layer made of Ni having a thickness of 50 nm was formed. By forming a composite coating layer composed of a Ni layer and an Au layer, surface-coated Au-Sn alloy powders 36 to 40 of the present invention and comparative surface-coated Au-Sn alloy powders 15 to 16 were produced. In this case, only the surface facing the target direction of the powder was coated, but the coverage of the Ni layer and the Au layer on the surface of the Au—Sn alloy powder was also measured by SEM observation. Liquid paraffin: 2.4% by mass and 2.6% by mass of paraffin wax were added to the obtained surface-coated Au-Sn alloy powders 36 to 40 of the present invention and the comparative surface-coated Au-Sn alloy powders 15 to 16, respectively. The mixture was mixed and dissolved by heating to produce a solder paste. Using these solder pastes, the solder spread rate was measured in accordance with the method specified in JIS Z 3197. At the same time, the Au-Sn alloy solder after melting was Au-Sn alloy powder by an optical microscope in the same manner as in Example 1. The presence or absence of an unmelted portion remaining without melting was observed, and the presence or absence of surface gloss was observed. The results are shown in Table 8.
[0036]
[Table 8]
From the results shown in Table 8, the solder paste containing the surface-coated Au-Sn alloy powders 36 to 40 of the present invention has a larger solder spread ratio than the solder paste containing the conventional Au-Sn alloy powder shown in Table 1. I understand. However, it can be seen that the solder pastes containing the comparative surface-coated Au-Sn alloy powders 15 to 16 which are out of the range of the present invention have insufficient solder spread.
[0038]
【The invention's effect】
As described above, the surface-coated Au-Sn alloy powder for a solder paste of the present invention, even when added to a rosin-free paste agent, is superior in wet spreadability as compared with a conventional solder paste, and contains rosin. There is no residue after brazing, so the cleaning process after brazing can be omitted, and good soldering can be performed, so that the cost can be reduced and industrially superior effects can be obtained. To bring.
Claims (7)
厚さ：１０〜１０００ｎｍを有するＦｅ、Ｃｒ、Ｎｉの内のいずれかの金属からなる拡散吸収防止層と、この拡散吸収防止層の上に形成された厚さ：１０〜１０００ｎｍを有するＡｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕの内のいずれかの貴金属からなる貴金属層とからなる複合コーティング層を形成してなることを特徴とするはんだペースト用表面被覆Ａｕ−Ｓｎ合金粉末。Sn: 15 to 25% by mass, the balance being on the surface of an Au-Sn alloy powder having a composition of Au and unavoidable impurities,
A diffusion / absorption prevention layer made of any one of Fe, Cr and Ni having a thickness of 10 to 1000 nm, and Au and Pt having a thickness of 10 to 1000 nm formed on the diffusion / absorption prevention layer , Rh, Pd, and Ru. A surface-coated Au-Sn alloy powder for a solder paste, comprising: forming a composite coating layer comprising a noble metal layer made of any one of noble metals.
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| JP2002310476A JP2004141937A (en) | 2002-10-25 | 2002-10-25 | Surface coated au-sn alloy powder for solder paste |
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| JP2002310476A JP2004141937A (en) | 2002-10-25 | 2002-10-25 | Surface coated au-sn alloy powder for solder paste |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006287226A (en) * | 2005-03-31 | 2006-10-19 | Osram Opto Semiconductors Gmbh | Semiconductor chip having layer sequence regulated for forming solder joints, and method for forming solder joint between support and the semiconductor chip |
| JP2006311337A (en) * | 2005-04-28 | 2006-11-09 | Kyocera Kinseki Corp | Driven electrode structure for crystal resonator, and manufacturing method thereof |
| WO2014087896A1 (en) | 2012-12-04 | 2014-06-12 | 三菱マテリアル株式会社 | Au-sn-bi alloy powder paste, au-sn-bi alloy thin film, and method for forming au-sn-bi alloy thin film |
| CN104384747A (en) * | 2014-10-08 | 2015-03-04 | 深圳市唯特偶新材料股份有限公司 | Cold-storage-free soldering tin paste and preparing method of cold-storage-free soldering tin paste |
| JP2017064725A (en) * | 2015-09-28 | 2017-04-06 | 三菱マテリアル株式会社 | Au-BASED SOLDER POWDER AND SOLDER PASTE INCLUDING THE POWDER |
| CN113385857A (en) * | 2021-06-15 | 2021-09-14 | 广东工业大学 | Multi-size micro-nano metal particle soldering paste in-situ interconnection process and product thereof |
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2002
- 2002-10-25 JP JP2002310476A patent/JP2004141937A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006287226A (en) * | 2005-03-31 | 2006-10-19 | Osram Opto Semiconductors Gmbh | Semiconductor chip having layer sequence regulated for forming solder joints, and method for forming solder joint between support and the semiconductor chip |
| JP2006311337A (en) * | 2005-04-28 | 2006-11-09 | Kyocera Kinseki Corp | Driven electrode structure for crystal resonator, and manufacturing method thereof |
| WO2014087896A1 (en) | 2012-12-04 | 2014-06-12 | 三菱マテリアル株式会社 | Au-sn-bi alloy powder paste, au-sn-bi alloy thin film, and method for forming au-sn-bi alloy thin film |
| CN104384747A (en) * | 2014-10-08 | 2015-03-04 | 深圳市唯特偶新材料股份有限公司 | Cold-storage-free soldering tin paste and preparing method of cold-storage-free soldering tin paste |
| JP2017064725A (en) * | 2015-09-28 | 2017-04-06 | 三菱マテリアル株式会社 | Au-BASED SOLDER POWDER AND SOLDER PASTE INCLUDING THE POWDER |
| CN113385857A (en) * | 2021-06-15 | 2021-09-14 | 广东工业大学 | Multi-size micro-nano metal particle soldering paste in-situ interconnection process and product thereof |
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