JP3794042B2

JP3794042B2 - Method for producing composite alloy member

Info

Publication number: JP3794042B2
Application number: JP26540295A
Authority: JP
Inventors: 正弘大町; 浩一高島; 紀人胡間
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 1995-10-13
Filing date: 1995-10-13
Publication date: 2006-07-05
Anticipated expiration: 2015-10-13
Also published as: JPH09111312A

Description

【０００１】
【発明の属する技術分野】
本発明は、粉末冶金法で製造される複合合金部材の製造方法に関する。より詳細には、本発明方法は、主成分としてＡｇ及び／又はＣｕと、Ｗ、Ｍｏ、Ｃｒ、ＷＣの少なくとも１種とを含む複合合金部材に関するものであり、主として電気接点、各種電極及び半導体装置等に用いられるものを対象とし、特に半導体装置用の各種部材の品質要求に応えるものである。
【０００２】
【従来の技術】
第１成分であるＡｇ及び／又はＣｕと、第２成分であるＷ、Ｍｏ、Ｃｒ、ＷＣの少なくとも１種とを主成分として組合せた複合合金材料は、Ａｇ及びＣｕの高い導電性及び熱伝導性と、Ｗ、Ｍｏ、Ｃｒ、ＷＣの高い耐熱性、耐アーク性及び剛性の特徴とを生かし、主として電気接点、スポット溶接ならびに放電加工等の各種電極、及びＳｉ等の半導体素子又はその集積回路を含む半導体装置用部材として広く用いられてきた。
【０００３】
これらの複合合金材料は、溶浸法又は焼結法と言われる周知の粉末冶金法によって製造される。溶浸法は、例えば半導体装置用Ｃｕ−Ｗ又はＣｕ−Ｍｏ基板を開示した特公平２−３１８６３号公報に記載されているように、主に上記第２成分からなる粉末成形体又は多孔質焼結体を形成し、これに第１成分を接触させた状態で溶融して成形体又は焼結体の空孔に溶浸充填する方法である。
【０００４】
一方、焼結法は、主に上記第１及び第２成分からなる混合組成の粉末成形体を、第１成分の溶融点以上の温度で焼成して第１成分の液相によって焼結するものである。又、予め、第１成分を少な目に混合し、その成形体又は多孔質焼結体を形成した後、これに追加の必要量の第１成分を接触状態で溶融して、成形体又は焼結体の残っている空孔に溶浸充填する、いわゆる予配合溶浸法という方法もある。
【０００５】
このような粉末冶金法では、いずれも第１成分の液相が焼成時に形成されるため、冷却後焼成物の外周表面に第１成分が溶出して残る。しかも、この溶出部分は凹部の底や凸部の立ち上がり外周部に多く残留しやすい。このため、最終製品にするためには、得られた溶浸体又は焼結体をほぼ全周にわたって加工除去し、第１成分の溶出部分を取り除く必要がある。
【０００６】
又、溶浸法での多孔質焼結体を形成する過程、及び焼結法での液相焼結の過程では焼成収縮が起こる。この焼成収縮は直前の成形体各部での成形密度差によって各部に収縮差が生じるため起こるのであり、その結果として変形が生じる。特に一軸の粉末プレス成形においては、成形型内への粉末の均一給粉がされていても、特にコーナー部分や外周の密度が高くなり、逆に内部の密度が低くなる傾向にあるため、成形時の形状が維持できない。なかでも本発明が対象とする剛性の高いＷ等の粉末成形においては、圧縮性の問題があるため、この収縮及び変形の現象が顕著に生じる。その結果、部品に要求される寸法精度のものを得るには、やはり全外周にわたって機械加工を施す必要がある。
【０００７】
本発明が対象とする素材、特にＷ、Ｍｏ、ＷＣ、Ａｇについては原料コストが高く、機械加工による取り代は要求寸法精度にもよるが極力少なくする必要があり、そのためには以上のような課題を克服しなければならない。又、複雑形状又は大型の成形体では密度差が生じると、最終的な複合合金材料中に第１成分の偏在が生じ、その結果、各部での熱膨張係数及び熱伝導度にもムラが発生したり、欠陥が生じたりする。例えば半導体装置用の部材にこの種のムラや欠陥が生じると、その熱膨張係数のムラからＮｉメッキ時の焼成によって変形が生じたり、欠陥による性能劣化や使用時の熱サイクルによって部分的又は致命的な損傷が生じ易くなり、高い信頼性の複合合金部材が得られない。このような事情は、電気接点並びに各種電極においても同様である。
【０００８】
静水圧成形によって成形体の密度差を解消することも考えられるが、この方法では粉末プレス成形のように連続した高速成形は不可能であり、生産性に乏しい。従って止むなく一軸の粉末プレス成形を行っている現状であるが、上記の理由から所望の製品形状寸法を得るためには外周をほぼ全周にわたって加工除去する必要があった。しかも、このようなプレス成形では、成形体一個一個の部分における密度の微妙な違いは、成形と同時に非破壊で解析することが難しく、仮に金型の上下杵の動きの微調整である程度は小さく抑えられたとしても、それとても金型費が嵩むという問題が潜在している。
【０００９】
例えば、図１に示すのような半導体装置用基板として段付形状部材１を製造する場合、粉末形成プレスによって部材と相似形の成形体を成形し、これを焼結するのであるが、焼結したものは鍔部２が変形する。このため、成形体を予め大き目に作り、焼結後の機械加工によって大き目の加工代部を除く方法か、又は予め突出部３を含むような最大厚みの単純な板状に成形すれば鍔部２の変形が緩和されるので、このような形状で焼結を行った後、機械加工により余分な箇所を大きく除去しているのが現状である。尚、段付形状部材に関しては、特開平５−２１１２４８号公報に記載のごとく、上段と下段の板に分けて成形し、これらを例えばＡｇ又はＣｕ板を介して重ね合わせ、焼成して一体化する方法も考えられる。しかし、この方法でも第２成分の溶出部を除去するため全面の機械加工は避けられない。
【００１０】
又、特開平７−１３５２７６号公報に記載のように、射出成形法によって第２成分粉末から成形密度が均一な相似形の成形体を作り、更に溶浸前に一面を残して各面に溶出防止剤を塗布して第１成分を溶浸し、溶出防止剤の存在しない一面を第１成分の溶出部と共に切削加工し、残る面は溶出防止剤残渣を簡単な加工によって取り除く方法が提案されている。しかしながら、この方法は、射出成形用の有機バインダーを用いるため、脱バインダー工程に手間がかかるという大きな問題がある。
【００１１】
更に、第１成分の液相での焼成を行う場合には、焼成時における成形体の収縮を予め抑えるために、成形体とする第２成分の出発原料粉末を粒径の粗い粉末と細かい粉末とで構成し、両粉末の配合によって充填性を上げる方法が“１９９４年ＩｎｔｅｒｎａｔｉｏｎａｌＣｏｎｆｅｒｅｎｃｅｏｎＴｕｎｇｓｔｅｎ”の２５３〜２５７頁に紹介されている。しかしながら、このような方法では、特殊な粒径のグレードの２種の原料粉末を準備しなければならず、原料費が嵩むという問題がある。
【００１２】
【発明が解決しようとする課題】
以上述べたように、Ｗ、Ｍｏ、Ｃｒ、ＷＣのような高剛性粉末を用いた粉末冶金法による複合合金部材においては、簡単且つ連続的な成形が可能で、しかも成形体各部の密度差による収縮や変形が少なく、後の除去加工箇所の削減などによる加工コストの低減が可能な製造方法は未だに提案されていない。
【００１３】
本発明は、かかる従来の事情に鑑み、Ａｇ及び／又はＣｕの第１成分と、Ｗ、Ｍｏ、Ｃｒ、及びＷＣの少なくとも１種の第２成分とからなる複合合金部材の製造における上記した問題点の解決法として、高い生産性で従来よりも均一な成形体が得られ、しかも溶浸体又は焼結体の仕上加工を削減し得る、安価且つ高品質な複合合金部材の製造方法を提供することを目的とする。
【００１４】
【課題を解決するための手段】
上記目的を達成するため、本発明が提供する複合金属材料の製造方法は、以下の第１の方法及び第２の方法からなる。
【００１５】
即ち、本発明の第１の方法は、Ａｇ及び／又はＣｕの第１成分と、Ｗ、Ｍｏ、Ｃｒ、及びＷＣの少なくとも１種の第２成分とからなる複合合金部材の製造方法であって、
(１ａ) 第２成分粉末を型押成形して、互いに平行な上面と下面を有し、その片方の面に一定の輪郭形状をなす凸部が形成され、他方の面の前記凸部とほぼ対応する位置に該凸部とほぼ同じ輪郭形状の凹部を有する成形体を得る工程と、
(１ｂ) 該成形体又は該成形体を焼成して得た多孔質焼結体において、その前記凸部又は凹部を設けた上面又は下面のいずれかを除く全ての面に、第１成分の溶出を防ぐ溶出防止剤を施す工程と、
(１ｃ) 該成形体又は多孔質焼結体の前記凸部又は凹部を設けた上面又は下面のうち溶出防止剤が施されていない面に第１成分を接触させた状態で、該第１成分を成形体又は多孔質焼結体の空孔に溶浸させて溶浸体を得る工程と、
(１ｄ) 該溶浸体の上面又は下面のうち溶出防止剤が施されていない面を溶出した第１成分と共に凸部又は凹部を含めて加工除去し、同時に又は前後してそれ以外の面の溶出防止剤残渣を除去する工程とを備えたことを特徴とする。
【００１６】
また、第２の方法は、Ａｇ又はＣｕの第１成分と、Ｗ、Ｍｏ、Ｃｒ、ＷＣの少なくとも１種の第２成分とからなる複合合金部材の製造方法であって、
(２ａ) 第１成分粉末と第２成分粉末との混合粉末を型押成形して、互いに平行な上面と下面を有し、その片方の面に一定の輪郭形状をなす凸部が形成され、他方の面の前記凸部とほぼ対応する位置に該凸部とほぼ同じ輪郭形状の凹部を有する成形体を得る工程と、
(２ｂ) 該成形体の前記凸部又は凹部を設けた上面又は下面のいずれかを除く全ての面に、第１成分の溶出を防ぐ溶出防止剤を施す工程と、
(２ｃ) 該成形体を第１成分の融点以上の温度で焼成して焼結体とする工程と、(２ｄ) 該焼結体の上面又は下面のうち溶出防止剤が施されていない面を溶出した第１成分と共に凸部又は凹部を含めて加工除去し、同時に又は前後してそれ以外の面の溶出防止剤残渣を除去する工程とを備えたことを特徴とする。
【００１７】
第１の方法において、一般的には(１ｂ)工程で成形体を焼結して多孔質焼結体とした後、この多孔質焼結体の空孔に(１ｃ)工程で第１成分を溶浸するのであるが、最終的な第１成分量が３０重量％を越える場合には(１ｂ)工程で焼結せず、成形体に溶出防止剤を施し、そのまま(１ｃ)工程で溶浸を行うことにより、溶浸と同時に成形体を焼成固化することができる。
【００１８】
尚、第１及び第２の方法で、(１ｄ)又は(２ｄ)工程により第１成分が溶出した面を加工除去した後、その状態のままでは要求寸法を達成できない寸法精度の厳しい部材については、更に熱間又は冷間での一軸再加圧を実施して精密な寸法調整（サイジング）を行うことができる。
【００１９】
【発明の実施の形態】
原料粉末において、Ａｇ及び／又はＣｕからなる第１成分粉末、及びＷ、Ｍｏ、Ｃｒ、ＷＣの少なくとも１種からなる第２成分粉末は、共に平均粒径が４０μｍ以下、好ましくは１０μｍ以下のものを用いる。平均粒径が４０μｍを越える粉末では、組成の均一性が低下するからである。又、第２成分粉末の平均粒径が４０μｍを越えると、成形時の圧縮性が著しく低下するため好ましくない。
【００２０】
成形用の第２成分粉末又は第１及び第２成分粉末の混合粉末中には、必要に応じて全体の１重量％までの鉄族元素、例えばＦｅ、Ｃｏ、Ｎｉの粉末を含ませてもよい。これによって第１成分の溶融物と第２成分固体との濡れ性が向上し、焼成時の緻密化が促進される。１重量％を越えた鉄族元素の添加は、複合金属材料の熱伝導性又は電気伝導性を必要とする用途には、それらが急激に低下するため好ましくない。
【００２１】
原料粉末の成形は、平行している上面と下面の対向するほぼ同じ位置に、それぞれ輪郭形状がほぼ等しい凸部と凹部が形成されるように行う。例えば、図１に示す段付形状部材１の場合には、図２のような形状の成形体４ａとなるように粉末成形を行う。即ち、一般的には平行な上下面の一方の面に一定の輪郭形状をなす凸部５を形成し、他方の対向する面には凸部５とほぼ対向する位置に凸部５とほぼ同じ輪郭形状の凹部６を形成するようにする。
【００２２】
成形方式は必ずしも限定されないが、最も簡単且つ容易な方法として、臼と上一段及び下一段の杵の組合せによる通常の一軸加圧による乾式成形プレス方式を用いることができる。例えば図１のような段付形状の複合合金部材を作る場合、図２の成形体形状となるように金型を設計する。このような成形体形状とすることによって、成形体の中央部と外周部の厚みの違いが小さくなるため、上下方向の圧縮力の充填粉末バルクへの伝播が全体的により一層均一になり、成形体中の成形密度差も従来の凸型断面形状とする場合に比べ顕著に小さく抑えられることが判った。
【００２３】
成形体密度がこのように均一になることにより、その後の焼成時の成形体の収縮レベルが全体でより一層均一になるため、焼成後の変形を著しく小さく抑えることができると共に、第１成分と第２成分の組成の部分的バラツキも著しく小さくなり、更に溶融した第１成分の外周への溶出についても例えば凹部の内側に偏在させうることも判明した。つまり、本発明の成形方法で成形されたものは、その後の焼成によっても成分偏析が小さく且つ成形時とほぼ相似形であって変形も小さく、更に第１成分の溶出物も凹部が貯りとなってそこに偏在させることができるのである。
【００２４】
以上のように金型の形状と成形時の動きの組合せを所望形状に応じて微調整することによって、成形体に凹凸があっても各部での粉末にかかる圧縮応力の均一化が図れるため、上面又は下面の一方にのみ凸部又は凹部を設けた場合に比べ、その各部での成分組成がより均一になり、各部での成形密度もより均一なものとなる。
【００２５】
上記した粉末成形においては、例えば図５に示す一軸加圧成形機のように、臼８に挿入される上杵９と下杵１０に設けた凸部又は凹部の周囲に小カットの面取りを施してＣ面１１を形成することが望ましく、これにより得られる成形体の凸部又は凹部の各外周コーナー部にラウンド部（Ｒ部）を付けることが望ましい。面取りとは、例えば図１０及び図１１のように、外周又はコーナーの部分を差し支えない程度に小さく削除することであり、削除によって作られた面をＣ面といい、図示するＣで面取りの大きさを定義する。また、Ｒ部取りとは、例えば図１２及び図１３に示すように、外周又はコーナーの部分を差し支えない程度に小さくラウンド面として削除することであり、削除によって作られた曲面をＲ面といい、図示する曲面の半径ＲでＲ部取りの大きさを定義する。
【００２６】
これらＣ面及びＲ部の具体的な大きさは、製品の寸法によって適切に付与するのが好ましい。Ｃ面を取ることによって成形体の金型からの離脱が容易になり、離脱時に生じ易い成形体の欠け及びクラック等の損傷が未然に防止される。又、Ｒ部の形成により、成形体の事後の取扱い時にコーナー部での成形体の欠けを未然に防止でき、形状の維持に有効である。
【００２７】
金型のその他の工夫としては、臼に上下方向の微小な抜きテーパーを付けることにより、成形体の離型が改善される。又、凸部と凹部の形成には、中杵（中駒）を上下に配して行うのが好ましい。このようにすることによって、上下杵と中杵の動きが分離され、より均一な圧縮条件の調節が可能となる。例えば、概ね軽く外形を成形したタイミングで中杵のみを作動させて、中杵に刻まれた特殊な形状部を成形すると共に、外形を圧縮して最終成形状を得ることが可能となる。かかる金型の工夫により、例えば図６に示すように、突出部３の周囲に溝１２を付したり、鍔部２の外周縁に小段差１３を設ける等、複雑形状の部材も自在に作製することが可能である。
【００２８】
次に、このような凸部と凹部を形成した成形体、又はこの成形体を焼結した多孔質焼結体の上面又は下面いずれかの一面を除く全ての面に、溶出防止剤を塗布する。例えば図１の段付形状部材１を作製する場合には、図２の成形体４ａのうち最終的に加工除去の必要な凹部６を含む一面を除く全ての面に溶出防止剤を塗布する。又、例えば図３のような箱型形状部材７の場合には、図４の成形体４ｂのうち最終的に加工除去を要する凸部５を含む一面を除く全ての面に溶出防止剤を塗布する。
【００２９】
溶出防止剤としては、焼成時において安定で、溶融した第１成分並びに固相の第２成分と反応せず、第１成分の溶融物と濡れない金属の酸化物、炭化物、窒化物等、又はそれらの２種以上の混合物を用いる。例えば、Ａｌ₂Ｏ₃、ＴｉＯ₂、ＳｉＯ₂、ＺｒＯ₂、ＡｌＮ、ＢＮ、Ｓｉ₃Ｎ₄、ＴｉＮ、ＺｒＮ、ＳｉＣ、ＺｒＣ、ＴｉＣ等が挙げられる。この中でも特にＴｉＮが、焼成時の安定性と加工除去の容易さの点で好ましい。尚、溶出防止剤を施すには、上記化合物の粉末をアルコール、アセトン等の揮発性有機溶剤中に分散させ、吹きつけるか又は刷毛等の手段で塗布する方法が簡単である。
【００３０】
溶出防止剤を施すことなく焼成すると、例えば溶浸法では第２成分からなる成形体の焼結によって形成される空孔の体積よりも若干多い第１成分を接触させ、第１成分を溶融して空孔中に浸透充填させるが、余剰の第１成分溶融物は冷却によって成形体焼成物の全表面に浸み出てくるため、全表面にわたって表層を加工除去しなければならない。又、焼結法においても同様に第１成分の液相が焼成とともに生じ、その第１成分が全表面にわたって浸み出てくるため、同様に全表面にわたる加工除去が必要となる。しかし、後に加工除去する一面以外の全ての面に予め溶出防止剤を施すことによって、溶出防止剤の存在する面への第１成分の溶出が防止されるため、その面の加工除去が必要でなくなる。
【００３１】
第１成分の浸み出しの大きな部分は溶出部と呼ばれ、通常この溶出部は焼成時の冷却の最も遅い部分に形成れるため、焼成物の一定の方向に溶出部を固めることはセッティングの状態をコントロールすることによりある程度可能であるが、この溶出部となる面以外の面にも第一成分の溶融析出膜が必ず形成される。
【００３２】
しかしながら、例えば図２の成形体４ａで、後の加工により必ず除去する面である凹部６を含む面に溶出部を集約すると共に、他の全面に上記溶出防止剤を予め塗布しておけば、その塗布面には第１成分の溶出が回避され、軽度に付着した溶出防止剤成分が残留した形態の焼成物が得られる。又、図４の成形体４ｂでも逆に凸部５に溶出部を集約し、他の全面に溶出防止剤を塗布すれば、同様の形態の焼成物が得られる。
【００３３】
この焼成物表面に残る溶出防止剤残渣は、簡単なブラストホーニング程度の加工で完全に除くことができる。しかも、当初から最終的に除去する予定の部分に溶出部が含まれるため、この溶出部を含む面のみを本格的な機械加工により除去すればよい。
【００３４】
そして、前記のごとく成形体は、従来のものに比べ密度が均一であり、組成も均一であるため、収縮による変形がほとんど生じない。従って、若干の変形が生じることに対応した成形時の肉盛りと、焼成後所望寸法公差に入るように成形形状を設計しておけば、溶出部を含む一面のみの加工除去によって所望形状の製品が得られる。又、加工によって生じる欠け、剥離等の加工欠陥の問題は、加工除去する面についてのみ配慮すればよい。更に、成形体でのこれら均質性は、得られる複合合金部材の不均質に基づく表面処理、接合時の加熱、冷却過程での変形を未然に回避するのに有効である。例えば半導体基板に利用する場合、事後のＮｉメッキ焼成時の反りの現象が回避され、また電極や電気接点に利用する場合のロウ付け時の変形が回避される。
【００３５】
又、溶出部を含めた溶出物の除去については、生産性の観点から焼成物の平行な面の一方を固定セットし、連続的に供給する両頭研磨による方法が望ましい。加工面の表面平滑性が要求される場合には、連続的に粗い砥石と細かな砥石を用い段階を分けて行う。例えば半導体基板の場合、溶出部と反対側の半導体素子の搭載面の面粗さを小さくするためには、図７に示すように、焼成物１４を超硬のチャック治具１５等を用いて固定し、砥石１６により溶出物１７を含む一面を最終加工面Ａまで除去すると同時に、反対側の面の凸部５も同時に研磨加工することができる。
【００３６】
更に、本発明の工程によって得られた最終の溶浸体又は焼結体では、溶出防止剤が存在せず従って溶出部を含んだ面が除去されれば、他の面には第１成分の溶出した皮膜が残らないため、一層高い寸法精度が要求れる場合であっても、除去加工後さらに熱間又は冷間の一軸再加圧を行うことで、再度精密な寸法調整（サイジング）ができる。この工程を取ることによって、かなり高い寸法精度の部材についても、切削や研磨加工による場合よりも、安価に且つ容易に最終寸法まで加工することが可能となる。
【００３７】
【実施例】
実施例１
図８はマイクロプロセッサーユニットの概略図であり、本発明の半導体用複合合金部材からなる保護カバー１８が基板１９に接合された半導体チップ２０を覆うように基板１９に固定されている。尚、この保護カバー１８は、図３に示す箱型形状部材７からなっている。
【００３８】
以下、上記保護カバー１８の製造工程を説明する。最初に、平均粒径３μｍのＷ粉末と平均粒径４μｍのＮｉ粉末とをそれぞれ９９.９重量％及び０.１重量％となるように配合し、混合して成形用混合粉末とした。尚、Ｎｉ粉末はＣｕの溶浸回りを良くする助剤である。次に、この混合粉末を１軸加圧成形機にて加圧成形し、図４に示す成形体を作製した。このとき用いた金型は図５とほぼ同じであり、上杵９の抜きテーパーは４５°、下杵１０の抜きテーパーは２°であった。段部寸法は、上杵９に比べ下杵１０を２割高くしたものを用いた。
【００３９】
この多孔成形体を水素ガス中において１２００℃で中間焼結した。このときの収縮率は５％であった。この時点での成形体は、収縮率が極くわずかであることもあり、反り及び変形等の歪みはなかった。得られた成形体の空孔率は３８体積％であった。図４に示すこの成形体の凸部５を含む一面を除いた表面全体に、溶出防止剤としてＢＮ粉末を塗布し、この成形体をその一面の寸法と同じ幅、長さに切り出した厚み１.０ｍｍの銅板の上に乗せ、水素雰囲気中で連続炉にて１１５０℃に加熱してＣｕの溶浸を行った。
【００４０】
溶浸後、塗布したＢＮ粉末を液体ホーニングで除去し、更にＣｕを溶浸させた一面の溶融Ｃｕ残渣を凸部と共に平面研磨により除去した。得られたＣｕ−Ｗ系複合合金部材を冷間にて５ｔｏｎ／ｃｍ²で再加圧し、図８の半導体装置用の保護カバー１８が完成した。この試料１と同様の方法により作製した各試料の複合合金部材について、中間焼結の温度、成形体の空孔率、溶浸防止剤、加圧法の有無を、試料１と共に下記１に示す。
【００４１】
【表１】

【００４２】
又、上記各試料の複合合金部材について、密度、熱伝導率及び熱膨張率を測定し、それぞれ表２に示した。尚、密度については、各試料共に５０個を測定した平均値であり、ほぼ理論密度通りになっており、成形体の空孔に完全にＣｕが溶浸したことがわかる。又、各部材の断面組織も欠陥がなく、溶出防止剤を塗布していた面にはＣｕ溶出物は全く見られなかった。
【００４３】
【表２】

【００４４】
又、各試料の複合合金部材について、半導体装置用の保護カバーとしての寸法精度のうち、特性上特に高精度が必要となる部分、即ち図３の箱型形状部材の外周縁の高さ及び凹部をなす底面の平面度をそれぞれ測定し、その寸法のばらつきを表３に示した。いずれも、要求精度を満たしていることが判る。
【００４５】
【表３】

【００４６】
実施例２
図９は本発明の複合合金部材である放熱基板２１を用いたマイクロプロセッサーユニットの概略図である。尚、この放熱基板２１は、図１に示す段付形状部材１で構成されている。前記実施例１と同様の方法により、下記表４に示す条件で各試料の放熱基板を作製した。ただし、一軸加圧成形機は、上２段及び下２段のプレスを用いた。
【００４７】
【表４】

【００４８】
又、上記各試料の複合合金部材について、密度、熱伝導率及び熱膨張率を測定し、それぞれ表５に示した。尚、密度については、各試料共に５０個を測定した平均値であり、形状が変わってもほぼ理論密度通りになっており、成形体の空孔に完全にＣｕが溶浸したことがわかる。又、各部材の断面組織も欠陥がなく、溶出防止剤を塗布していた面にはＣｕ溶出物は全く見られなかった。
【００４９】
【表５】

【００５０】
又、各試料の複合合金部材について、半導体装置用の放熱基板としての寸法精度のうち、特性上特に高精度が必要となる部分、即ち図１の段付形状部材の最大厚み部の厚み及び凸部をなす面の平面度をそれぞれ測定し、その寸法のばらつきを表６に示した。いずれも、要求精度を満たしていることが判る。
【００５１】
【表６】

【００５２】
実施例３
上記実施例１と同様にして、しかし中間焼結等の条件を下記表７のごとく変化させ、下記各試料のＣｕ−Ｗ接点及び放電加工用電極を作製した。又、得られた各試料について、密度を測定した結果を表７に併せて示した。
【００５３】
【表７】

【００５４】
密度については、実施例１と同様に各試料５０個について測定した平均値であり、形状が変わってもほぼ理論密度通りになっており、成形体の空孔に完全にＣｕが溶浸したことがわかる。又、各試料の断面組織も欠陥がなく、溶出防止剤を塗布していた面にはＣｕの溶出物は全く見られなかった。
【００５５】
このことから、得られた本発明の複合合金部材は、電気接点として、電気電導度、硬度及び合金組織を各部で確認し、又放電加工用電極として同様の特性を各部で確認したが、それぞれのレベル及びｎ＝５０個での特性のバラツキも少なく、十分な特性を有していることが判った。又、各部の寸法についても、要求精度に充分入るレベルであり、溶出部以外の加工は不要であった。
【００５６】
実施例４
前記実施例１と同じく図８に示す半導体装置用の保護カバーを、実施例１と同様にして作製した。ただし、Ｗ粉末の代わりにＭｏ粉末を使用した。即ち、平粒径３μｍのＭｏ粉末と平均粒径４μｍのＮｉ粉末とを、それぞれ９９.９重量％及び０.１重量％となるように配合し、混合して成型用の混合粉末とした。以下の工程は、実施例１のと同じであるが、中間焼結その他の条件は下記表８に示す通りとした。
【００５７】
【表８】

【００５８】
又、上記各試料の複合合金部材について、密度、熱伝導率及び熱膨張率を測定し、それぞれ表９に示した。尚、密度については、各試料共に５０個を測定した平均値であり、ほぼ理論密度通りになっており、成形体の空孔に完全にＣｕが溶浸したことがわかる。又、各部材の断面組織も欠陥がなく、溶出防止剤を塗布していた面にはＣｕ溶出物は全く見られなかった。
【００５９】
【表９】

【００６０】
又、各試料の複合合金部材について、半導体装置用の保護カバーとしての寸法精度のうち、特性上特に高精度が必要となる部分、即ち図３の箱型形状部材の外周縁の高さ及び凹部をなす底面の平面度をそれぞれ測定し、その寸法のばらつきを表１０に示した。いずれも、要求精度を満たしていることが判る。
【００６１】
【表１０】

【００６２】
実施例５
実施例１と同じＷ粉末及びＮｉ粉末を用い、Ｃｕ粉末は平均粒径４μｍのものを使用して、実施例１と同様の図８のごとく使用される保護カバーを作製した。即ち、Ｗ粉末とＮｉ粉末の量は実施例１と同様に９９.９重量％及び０.１重量％とし、これらの粉末とＣｕ粉末とを下記表１１に示す組成となるように配合して均一に混合し、成形用混合粉末とした。
【００６３】
次に、各混合粉末を実施例１と同様に加圧成形を行い、図４に示す成形体を作製した。この時用いた金型は実施例１と同じものである。図４に示す成形体の凸部５を含む一面を除いた表面全体に溶出防止剤としてＢＮ粉末を塗布した後、その成形体を水素ガス中においてそれぞれ表１１に示す温度で焼結した。得られた各焼結体の形状は、元の成形体の形状に比べて大きな歪み又は変形はなかった。また、得られた各焼結体の密度は９８％以上であった。
【００６４】
焼結体表面の残留ＢＮ粉末を液体ホーニングで除去し、更にＢＮ粉末が塗布されていない一面に溶出したＣｕ残渣を凸部と共に平面研磨により除去し、図３に示す形状の保護カバーを得た。また、一部の保護カバーについては、実施例１と同様に再加圧を施した。以上のごとく作製した各保護カバーの複合合金部材について、その組成を焼結温度及び加圧法の有無と共に、表１１に示す。
【００６５】
【表１１】

【００６６】
上記各試料の複合合金部材について、密度、熱伝導率及び熱膨張率を測定し、その結果を表１２に示した。尚、密度については各試料共に５０個を測定した平均値であり、ほぼ理論密度に近い値となっており、空孔は認められなかった。また、各部材の断面組織も欠陥がなく、溶出防止剤を塗布した面にはＣｕ溶出物は全く見られなかった。
【００６７】
【表１２】

【００６８】
更に、上記のごとく作製した各保護カバーの寸法精度を、実施例１と同様に測定し評価した。即ち、図３の箱型形状部材の外周縁の高さ及び凹部をなす底面の平面度をそれぞれ測定し、その寸法のばらつきを表１３に示した。いずれも要求精度を満たしていることが判る。
【００６９】
【表１３】

【００７０】
実施例６
上記実施例１と同じく図８に示す半導体用保護カバーを、Ｃｕの代わりにＡｇを溶浸させた以外は実施例１と同様に作製した。ただし、Ａｇの溶浸については、溶出防止剤を塗布した図４の成形体を、その一面の寸法と同じ幅及び長さに切り出した厚み１.０ｍｍの銀板の上に載せ、水素雰囲気中で連続炉にて溶浸を行った。
【００７１】
また、同じ保護カバーを、Ｗ粉末の代わりにＣｒ粉末を用いて実施例１と同様に作製した。即ち、平均粒径３μｍのＣｒ粉末を１軸加成形機にて加圧成形し、図４に示す形状の成形体を得た。以下の工程は実施例１と同様である。得られた各複合合金部材の合金組成を、中間焼結の温度、溶出防止剤、再加圧の有無と共に、表１４に示す。
【００７２】
【表１４】

【００７３】
得られた各複合合金部材の密度、熱伝導率、及び熱膨張率を表１５に、また得られた図３の箱型形状部材の外周縁の高さ及び凹部をなす底面の平面度をそれぞれ測定し、その寸法のばらつきを表１６に示した。いずれも実施例１〜５と同様の本発明の効果が得られた。また、Ｃｕの溶浸回りを良くするために、平均粒径４μｍのＮｉ粉末を上記Ｃｒ粉末９９.９重量％に対して０.１重量％となるように配合し、上記と同様にして作製した複合合金部材についても、同様の結果が得られた。
【００７４】
【表１５】

【００７５】
【表１６】

【００７６】
【発明の効果】
本発明によれば、Ａｇ及び／又はＣｕの第１成分と、Ｗ、Ｍｏ、Ｃｒ、及びＷＣの少なくとも１種の第２成分とからなる複合合金部材の製造において、成形体形状を工夫することで高い生産性で従来よりも均一な成形体が得られ、従ってこの成形体から得られる溶浸体又は焼結体の反りや変形等を低減させることができ、同時に溶出防止剤を用いて第１成分の溶出を所定の仕上加工箇所に限ることができるので、後の仕上げ加工を削減し、安価で且つ高品質な複合合金部材の製造方法を提供することができる。
【図面の簡単な説明】
【図１】本発明に係わる複合合金部材からなる段付形状部材の斜視図である。
【図２】図１の段付形状部材の製造に用いる成形体の断面図である。
【図３】本発明に係わる複合合金部材からなる箱型形状部材の斜視図である。
【図４】図３の箱型形状部材の製造に用いる成形体の断面図である。
【図５】成形体の作製に用いる一軸加圧成形機の金型部分を示す概略の断面図である。
【図６】本発明方法により製造される複雑形状の複合合金部材の一例を示す断面図である。
【図７】本発明方法において焼成体の一部を機械加工により除去する工程を示す概略の断面図である。
【図８】箱型形状部材の保護カバーを備えた半導体装置の概略の断面図である。
【図９】段付形状部材の放熱基板を備えた半導体装置の概略の断面図である。
【図１０】面取りの一例を示す斜視図である。
【図１１】面取りの他の例を示す斜視図である。
【図１２】Ｒ部取りの一例を示す斜視図である。
【図１３】Ｒ部取りの他の例を示す斜視図である。
【符号の説明】
１段付形状部材
２鍔部
３突出部
４ａ成形体
４ｂ成形体
５凸部
６凹部
７箱型形状部材
８臼
９上杵
１０下杵
１１Ｃ面
１２溝
１３小段差
１４焼成物
１５チャック治具
１６砥石
１７溶出物
１８保護カバー
１９基板
２０半導体チップ
２１放熱基板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a composite alloy member manufactured by powder metallurgy. More specifically, the method of the present invention relates to a composite alloy member containing Ag and / or Cu as main components and at least one of W, Mo, Cr, and WC, and mainly includes electrical contacts, various electrodes, and semiconductors. It is intended for use in devices and the like, and in particular, meets the quality requirements of various members for semiconductor devices.
[0002]
[Prior art]
A composite alloy material in which Ag and / or Cu as the first component and at least one of W, Mo, Cr, and WC as the main components are combined as a main component has high conductivity and heat conduction of Ag and Cu. And the high heat resistance, arc resistance, and rigidity characteristics of W, Mo, Cr, and WC, mainly various electrodes for electrical contacts, spot welding and electric discharge machining, and semiconductor elements such as Si or their integrated circuits It has been widely used as a member for a semiconductor device including
[0003]
These composite alloy materials are manufactured by a well-known powder metallurgy method called an infiltration method or a sintering method. For example, as described in JP-B-2-31863, which discloses a Cu-W or Cu-Mo substrate for a semiconductor device, the infiltration method is mainly a powder molded body or a porous sintered body composed of the second component. In this method, a kneaded body is formed, melted in a state where the first component is brought into contact therewith, and infiltrated and filled into the pores of the molded body or sintered body.
[0004]
On the other hand, in the sintering method, a powder molded body having a mixed composition mainly composed of the first and second components is fired at a temperature equal to or higher than the melting point of the first component and sintered by the liquid phase of the first component. It is. In addition, the first component is mixed in advance to form a compact or porous sintered body, and then an additional necessary amount of the first component is melted in contact with the molded body or sintered. There is also a so-called pre-mixed infiltration method in which the voids remaining in the body are infiltrated and filled.
[0005]
In such powder metallurgy, since the liquid phase of the first component is formed during firing, the first component is eluted and remains on the outer peripheral surface of the fired product after cooling. Moreover, a large amount of this elution portion tends to remain on the bottom of the concave portion and the rising outer periphery of the convex portion. For this reason, in order to obtain a final product, it is necessary to process and remove the obtained infiltrated body or sintered body over almost the entire circumference to remove the elution portion of the first component.
[0006]
Further, firing shrinkage occurs in the process of forming a porous sintered body by the infiltration method and in the process of liquid phase sintering by the sintering method. This firing shrinkage occurs because a shrinkage difference occurs in each part due to a molding density difference in each part of the molded body immediately before, and as a result, deformation occurs. Especially in uniaxial powder press molding, even if the powder is uniformly fed into the mold, the density of the corner and outer periphery tends to increase, and conversely the internal density tends to decrease. The shape of the time cannot be maintained. Among these, in the powder molding of high rigidity W or the like targeted by the present invention, there is a problem of compressibility, so that the phenomenon of shrinkage and deformation occurs remarkably. As a result, in order to obtain the dimensional accuracy required for the parts, it is also necessary to perform machining on the entire outer periphery.
[0007]
The raw material costs of the materials targeted by the present invention, particularly W, Mo, WC, and Ag, are high, and the machining allowance needs to be reduced as much as possible depending on the required dimensional accuracy. We must overcome the challenges. In addition, when a density difference occurs in a complex shape or large compact, uneven distribution of the first component occurs in the final composite alloy material, resulting in uneven thermal expansion coefficient and thermal conductivity in each part. Or cause defects. For example, when this kind of unevenness or defect occurs in a member for a semiconductor device, deformation occurs due to firing during Ni plating due to the uneven thermal expansion coefficient, or partial or fatal due to performance deterioration due to a defect or thermal cycle during use. Damage is likely to occur, and a highly reliable composite alloy member cannot be obtained. Such a situation is the same for electrical contacts and various electrodes.
[0008]
Although it is conceivable to eliminate the density difference of the molded body by isostatic pressing, this method cannot perform continuous high-speed molding like powder press molding, and is poor in productivity. Accordingly, the present situation is that uniaxial powder press molding is unavoidably performed. However, in order to obtain a desired product shape dimension, it has been necessary to process and remove the outer circumference over almost the entire circumference. Moreover, in such press molding, it is difficult to analyze the subtle differences in the density of each part of the molded body in a non-destructive manner at the same time as molding. Even if it is suppressed, there is a potential problem that the mold cost is very high.
[0009]
For example, when manufacturing the step-shaped member 1 as a substrate for a semiconductor device as shown in FIG. 1, a molded body similar to the member is formed by a powder forming press, and this is sintered. As a result, the collar 2 is deformed. For this reason, if the molded body is made large in advance and the large machining allowance is removed by machining after sintering, or if it is molded into a simple plate having the maximum thickness so as to include the protruding portion 3 in advance, the collar portion Since the deformation of No. 2 is relaxed, after the sintering is performed in such a shape, an excessive portion is largely removed by machining. As for the stepped shape member, as described in Japanese Patent Laid-Open No. 5-21248, it is divided into upper and lower plates, and these are laminated by, for example, Ag or Cu plates and integrated by firing. A way to do this is also conceivable. However, even with this method, machining of the entire surface is inevitable because the elution portion of the second component is removed.
[0010]
Also, as described in Japanese Patent Laid-Open No. 7-135276, a molded product having a uniform molding density with a uniform molding density is made from the second component powder by an injection molding method. A method is proposed in which the first component is infiltrated by applying an inhibitor, cutting one surface with no elution inhibitor together with the elution portion of the first component, and removing the dissolution inhibitor residue on the remaining surface by simple processing. Yes. However, since this method uses an organic binder for injection molding, there is a big problem that it takes time to remove the binder.
[0011]
Furthermore, when firing in the liquid phase of the first component, in order to suppress in advance the shrinkage of the molded body during firing, the starting raw material powder of the second component used as the molded body is a coarse powder and a fine powder. A method for improving the filling property by blending both powders is introduced in pages 253 to 257 of “1994 International Conference on Tungsten”. However, in such a method, there is a problem that two kinds of raw material powders having a special particle size grade must be prepared, and the raw material cost increases.
[0012]
[Problems to be solved by the invention]
As described above, in the composite alloy member by the powder metallurgy method using high-rigidity powder such as W, Mo, Cr, and WC, simple and continuous molding is possible, and further, due to the density difference of each part of the molded body. There has not yet been proposed a manufacturing method that has little shrinkage and deformation and that can reduce the processing cost by reducing the number of parts to be removed later.
[0013]
In view of such conventional circumstances, the present invention has the above-described problems in the production of a composite alloy member comprising a first component of Ag and / or Cu and at least one second component of W, Mo, Cr, and WC. As a point solution, a low-cost and high-quality composite alloy member manufacturing method is provided that can produce a more compact molded body with higher productivity than before and can reduce the finishing of the infiltrated body or sintered body. The purpose is to do.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing a composite metal material provided by the present invention comprises the following first method and second method.
[0015]
That is, the first method of the present invention is a method for producing a composite alloy member comprising a first component of Ag and / or Cu and at least one second component of W, Mo, Cr, and WC. ,
(1a) The second component powder is embossed and has an upper surface and a lower surface that are parallel to each other, and a convex portion having a constant contour shape is formed on one surface thereof, and substantially the same as the convex portion on the other surface. A step of obtaining a molded body having a concave portion having substantially the same contour shape as the convex portion at a corresponding position;
(1b) In the porous sintered body obtained by firing the molded body or the molded body, the first component is eluted on all surfaces except the upper surface or the lower surface provided with the convex portion or the concave portion. Applying an anti-elution agent to prevent
(1c) The first component in a state where the first component is brought into contact with the upper surface or the lower surface of the molded body or the porous sintered body provided with the convex portion or the concave portion, to which the elution inhibitor is not applied. Infiltrating into the pores of the molded body or porous sintered body to obtain an infiltrated body,
(1d) The surface of the infiltrated body that is not subjected to the dissolution inhibitor is removed together with the first component that has been eluted, including the convex portion or the concave portion, and simultaneously or back and forth on the other surface. And a step of removing the dissolution inhibitor residue.
[0016]
The second method is a method for producing a composite alloy member comprising a first component of Ag or Cu and at least one second component of W, Mo, Cr, and WC,
(2a) A mixed powder of the first component powder and the second component powder is embossed to have an upper surface and a lower surface parallel to each other, and a convex portion having a constant contour shape is formed on one surface thereof, Obtaining a molded body having a concave portion having substantially the same contour shape as the convex portion at a position substantially corresponding to the convex portion on the other surface;
(2b) applying an elution inhibitor that prevents elution of the first component to all surfaces except either the upper surface or the lower surface provided with the convex portion or the concave portion of the molded body;
(2c) firing the molded body at a temperature equal to or higher than the melting point of the first component to form a sintered body; and (2d) a surface of the sintered body on which no elution inhibitor is applied. And a step of processing and removing together with the eluted first component including the convex portion or the concave portion and removing the dissolution inhibitor residue on the other surface simultaneously or before and after.
[0017]
In the first method, generally, after the compact is sintered in the step (1b) to form a porous sintered body, the first component is added to the pores of the porous sintered body in the step (1c). If the final amount of the first component exceeds 30% by weight, it is not sintered in the step (1b), and an elution inhibitor is applied to the molded body, and the infiltration is performed in the step (1c) as it is. By performing this, the molded body can be fired and solidified simultaneously with the infiltration.
[0018]
For parts with severe dimensional accuracy that cannot achieve the required dimensions in that state after the first and second methods have processed and removed the surface from which the first component has eluted in step (1d) or (2d). Furthermore, precise dimensional adjustment (sizing) can be performed by performing uniaxial re-pressurization in hot or cold.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In the raw material powder, the first component powder composed of Ag and / or Cu and the second component powder composed of at least one of W, Mo, Cr and WC both have an average particle diameter of 40 μm or less, preferably 10 μm or less. Is used. This is because the uniformity of the composition is reduced when the average particle size exceeds 40 μm. On the other hand, if the average particle size of the second component powder exceeds 40 μm, the compressibility at the time of molding is remarkably lowered, which is not preferable.
[0020]
The second component powder for molding or the mixed powder of the first and second component powders may contain powder of iron group element, for example, Fe, Co, Ni up to 1% by weight of the total if necessary. Good. This improves the wettability between the melt of the first component and the second component solid, and promotes densification during firing. Addition of iron group elements in excess of 1% by weight is not preferable for applications that require the thermal conductivity or electrical conductivity of the composite metal material because they rapidly decrease.
[0021]
The raw material powder is molded such that convex portions and concave portions having substantially the same contour shape are formed at substantially the same positions on the parallel upper surface and lower surface, respectively. For example, in the case of the stepped shape member 1 shown in FIG. 1, powder molding is performed so as to obtain a molded body 4a having a shape as shown in FIG. That is, generally, a convex portion 5 having a constant contour shape is formed on one of the parallel upper and lower surfaces, and the other opposing surface is substantially the same as the convex portion 5 at a position substantially opposed to the convex portion 5. A contour-shaped recess 6 is formed.
[0022]
The forming method is not necessarily limited, but as the simplest and easiest method, a dry forming press method using a normal uniaxial pressing with a combination of a mortar and an upper one step and a lower one step can be used. For example, when a stepped-shaped composite alloy member as shown in FIG. 1 is made, the mold is designed so as to have the shape of the molded body shown in FIG. By adopting such a molded body shape, the difference in thickness between the central part and the outer peripheral part of the molded body is reduced, so that the propagation of the compressive force in the vertical direction to the filled powder bulk becomes more uniform overall, and the molding It has been found that the difference in molding density in the body can be significantly reduced as compared with the conventional convex cross-sectional shape.
[0023]
Since the density of the molded body becomes uniform in this way, the level of shrinkage of the molded body at the time of subsequent firing becomes even more uniform as a whole, so that deformation after firing can be significantly reduced, and the first component and It has also been found that the partial variation in the composition of the second component is remarkably reduced, and that the melted first component can be evenly distributed, for example, inside the recess. In other words, the material molded by the molding method of the present invention has small component segregation even by subsequent firing, is almost similar to that at the time of molding, and has little deformation. It can be unevenly distributed there.
[0024]
As described above, by finely adjusting the combination of the shape of the mold and the movement at the time of molding according to the desired shape, even if the molded body has irregularities, it is possible to equalize the compressive stress applied to the powder in each part. Compared with the case where the convex portion or the concave portion is provided only on one of the upper surface and the lower surface, the component composition in each portion becomes more uniform, and the molding density in each portion becomes more uniform.
[0025]
In the powder molding described above, for example, as in the uniaxial pressure molding machine shown in FIG. 5, small cut chamfering is performed around the convex portions or concave portions provided on the upper and

lower punches

9 and 10 inserted into the die 8. Thus, it is desirable to form the C surface 11, and it is desirable to add a round portion (R portion) to each outer peripheral corner portion of the convex portion or the concave portion of the molded body obtained thereby. The chamfering is, for example, as shown in FIG. 10 and FIG. 11, where the outer periphery or the corner portion is deleted as small as it does not interfere, and the surface created by the deletion is referred to as the C surface. Define Further, the R-part removal means, for example, as shown in FIG. 12 and FIG. 13, that the outer periphery or the corner portion is deleted as small as a round surface, and the curved surface created by the deletion is called the R surface. The size of the R portion is defined by the radius R of the curved surface shown in the figure.
[0026]
It is preferable that the specific sizes of the C surface and the R portion are appropriately given according to the dimensions of the product. By taking the C surface, the molded body can be easily detached from the mold, and damage such as chipping and cracking of the molded body, which is likely to occur at the time of separation, is prevented. In addition, the formation of the R portion can prevent the molded body from being chipped at the corner during subsequent handling of the molded body, and is effective in maintaining the shape.
[0027]
As another contrivance of the mold, mold release of the molded body can be improved by attaching a fine vertical taper to the die. Moreover, it is preferable to form a convex part and a recessed part by arranging a middle collar (medium piece) up and down. By doing so, the movements of the upper and lower kites and the middle kites are separated, and the compression conditions can be adjusted more uniformly. For example, it is possible to operate only the inner collar at the timing when the outer shape is formed lightly and form a special shape portion engraved in the inner casing, and compress the outer shape to obtain a final molded shape. By devising such a mold, for example, as shown in FIG. 6, a member having a complicated shape can be freely produced, for example, a groove 12 is provided around the protrusion 3 or a small step 13 is provided on the outer periphery of the flange 2. Is possible.
[0028]
Next, an elution inhibitor is applied to all surfaces except one surface of the molded body in which such convex portions and concave portions are formed, or the porous sintered body obtained by sintering the molded body. . For example, when the stepped shape member 1 shown in FIG. 1 is manufactured, an elution preventing agent is applied to all surfaces of the molded body 4a shown in FIG. For example, in the case of the box-shaped member 7 as shown in FIG. 3, an elution inhibitor is applied to all surfaces of the molded body 4b shown in FIG. To do.
[0029]
Anti-elution agents include metal oxides, carbides, nitrides, etc. that are stable during firing, do not react with the melted first component and the second component of the solid phase, and do not wet the melt of the first component, or A mixture of two or more of them is used. For example, Al₂O_ThreeTiO₂, SiO₂, ZrO₂, AlN, BN, Si_ThreeN_FourTiN, ZrN, SiC, ZrC, TiC and the like. Of these, TiN is particularly preferable in terms of stability during firing and ease of processing removal. In order to apply the dissolution inhibitor, it is easy to disperse the above-mentioned compound powder in a volatile organic solvent such as alcohol or acetone and apply it by spraying or using means such as a brush.
[0030]
When firing without applying an elution inhibitor, for example, in the infiltration method, the first component is brought into contact with the first component slightly larger than the volume of pores formed by sintering of the molded body composed of the second component, and the first component is melted. However, since the surplus first component melt oozes out on the entire surface of the fired product by cooling, the surface layer must be processed and removed over the entire surface. Similarly, in the sintering method, the liquid phase of the first component is generated along with the firing, and the first component oozes over the entire surface. However, since the elution of the first component to the surface where the anti-elution agent exists is prevented by preliminarily applying the elution inhibitor to all surfaces other than one surface to be processed and removed later, it is necessary to process and remove the surface. Disappear.
[0031]
The large portion of the first component that oozes out is called the elution part. Normally, this elution part is formed in the slowest part of cooling at the time of firing, so solidifying the elution part in a certain direction of the fired product is a setting. Although it is possible to some extent by controlling the state, a melt-deposited film of the first component is always formed on a surface other than the surface to be the elution portion.
[0032]
However, for example, in the molded body 4a of FIG. 2, if the elution part is concentrated on the surface including the recess 6 which is a surface that must be removed by subsequent processing, and the above-mentioned elution inhibitor is applied in advance to the other entire surface, On the coated surface, elution of the first component is avoided, and a fired product in a form in which a lightly attached elution inhibitor component remains is obtained. Also, in the molded body 4b of FIG. 4, if the elution part is concentrated on the convex part 5 and the other part is coated with an elution inhibitor, a fired product having the same form can be obtained.
[0033]
The dissolution agent residue remaining on the surface of the fired product can be completely removed by a process of a simple blast honing degree. And since the elution part is contained in the part which is finally planned to be removed from the beginning, only the surface including this elution part should be removed by full-scale machining.
[0034]
And as above-mentioned, since a molded object has a uniform density compared with the conventional one and a composition is uniform, the deformation | transformation by shrinkage hardly arises. Therefore, if the molding shape is designed so as to fall within the desired dimensional tolerance after firing corresponding to the slight deformation, the product of the desired shape can be obtained by processing and removing only one surface including the elution part. Is obtained. Further, the problem of processing defects such as chipping and peeling caused by processing need only be considered for the surface to be processed and removed. Furthermore, these homogeneities in the compact are effective in avoiding deformation during the surface treatment based on the heterogeneity of the obtained composite alloy member, heating during the joining, and cooling. For example, when used for a semiconductor substrate, a warping phenomenon at the time of subsequent Ni plating firing is avoided, and deformation at the time of brazing when used for an electrode or an electrical contact is avoided.
[0035]
Further, for removal of the eluate including the elution part, it is desirable to use a double-head polishing method in which one of the parallel surfaces of the fired product is fixedly set and supplied continuously from the viewpoint of productivity. When the surface smoothness of the processed surface is required, the steps are continuously performed using a rough grindstone and a fine grindstone. For example, in the case of a semiconductor substrate, in order to reduce the surface roughness of the mounting surface of the semiconductor element on the side opposite to the elution portion, as shown in FIG. At the same time, the entire surface including the eluate 17 is removed to the final processing surface A by the grindstone 16, and the convex portion 5 on the opposite surface can be simultaneously polished.
[0036]
Furthermore, in the final infiltrated body or sintered body obtained by the process of the present invention, there is no elution inhibitor, so if the surface including the elution portion is removed, the other surface contains the first component. Since the eluted film does not remain, even when higher dimensional accuracy is required, precise dimensional adjustment (sizing) can be performed again by performing hot or cold uniaxial re-pressurization after removal processing. . By taking this step, it is possible to process a member with considerably high dimensional accuracy to the final dimension at a lower cost and more easily than by cutting or polishing.
[0037]
【Example】
Example 1
FIG. 8 is a schematic view of a microprocessor unit, and a protective cover 18 made of a composite alloy member for semiconductor of the present invention is fixed to the substrate 19 so as to cover the semiconductor chip 20 bonded to the substrate 19. The protective cover 18 is composed of a box-shaped member 7 shown in FIG.
[0038]
Hereinafter, the manufacturing process of the protective cover 18 will be described. First, W powder having an average particle size of 3 μm and Ni powder having an average particle size of 4 μm were blended so as to be 99.9% by weight and 0.1% by weight, respectively, and mixed to obtain a mixed powder for molding. Ni powder is an auxiliary agent that improves the infiltration of Cu. Next, this mixed powder was pressure-molded with a uniaxial pressure molding machine to produce a molded body shown in FIG. The mold used at this time was almost the same as that shown in FIG. 5, and the upper taper 9 had a draft taper of 45 °, and the lower collar 10 had a taper taper of 2 °. The step size was 20% higher than that of the upper eyelid 9 by 20%.
[0039]
This porous molded body was subjected to intermediate sintering at 1200 ° C. in hydrogen gas. The shrinkage rate at this time was 5%. The molded body at this point had a very small shrinkage rate, and there was no distortion such as warpage and deformation. The porosity of the obtained molded body was 38% by volume. A thickness 1 obtained by applying BN powder as an elution inhibitor to the entire surface excluding one surface including the convex portion 5 of the molded body shown in FIG. 4, and cutting the molded body into the same width and length as the one surface. It was placed on a copper plate of 0.0 mm and heated to 1150 ° C. in a continuous furnace in a hydrogen atmosphere to infiltrate Cu.
[0040]
After infiltration, the applied BN powder was removed by liquid honing, and the molten Cu residue on one surface infiltrated with Cu was removed together with the convex portions by planar polishing. The obtained Cu—W based composite alloy member was cooled at 5 ton / cm.²Then, the protective cover 18 for the semiconductor device of FIG. 8 was completed. With respect to the composite alloy member of each sample produced by the same method as that of Sample 1, the intermediate sintering temperature, the porosity of the compact, the infiltration inhibitor, and the presence or absence of the pressurizing method are shown in Table 1 below together with Sample 1.
[0041]
[Table 1]

[0042]
Further, the density, thermal conductivity and coefficient of thermal expansion of the composite alloy member of each sample were measured and are shown in Table 2. In addition, about a density, it is an average value which measured 50 pieces for each sample, and it is almost according to a theoretical density, and it turns out that Cu infiltrated into the void | hole of a molded object completely. Moreover, the cross-sectional structure of each member was also free from defects, and Cu eluate was not seen at all on the surface where the dissolution inhibitor was applied.
[0043]
[Table 2]

[0044]
Further, for the composite alloy member of each sample, among the dimensional accuracy as a protective cover for a semiconductor device, a portion that requires particularly high accuracy in terms of characteristics, that is, the height and recess of the outer peripheral edge of the box-shaped member in FIG. The flatness of the bottom surface forming each was measured, and the dimensional variation was shown in Table 3. It can be seen that both satisfy the required accuracy.
[0045]
[Table 3]

[0046]
Example 2
FIG. 9 is a schematic view of a microprocessor unit using a heat dissipation substrate 21 which is a composite alloy member of the present invention. In addition, this thermal radiation board | substrate 21 is comprised by the step-shaped member 1 shown in FIG. By the same method as in Example 1, a heat dissipation substrate for each sample was produced under the conditions shown in Table 4 below. However, the uniaxial pressure molding machine used upper and lower two-stage presses.
[0047]
[Table 4]

[0048]
Further, the density, thermal conductivity and coefficient of thermal expansion of the composite alloy members of the above samples were measured and are shown in Table 5. The density is an average value obtained by measuring 50 samples for each sample, and it is almost the theoretical density even when the shape is changed, and it can be seen that Cu has completely infiltrated into the pores of the molded body. Moreover, the cross-sectional structure of each member was also free from defects, and Cu eluate was not seen at all on the surface where the dissolution inhibitor was applied.
[0049]
[Table 5]

[0050]
Further, regarding the composite alloy member of each sample, among the dimensional accuracy as a heat dissipation substrate for a semiconductor device, the portion that requires particularly high accuracy in terms of characteristics, that is, the thickness and convexity of the maximum thickness portion of the stepped shape member of FIG. The flatness of the surface forming the part was measured, and the dimensional variation was shown in Table 6. It can be seen that both satisfy the required accuracy.
[0051]
[Table 6]

[0052]
Example 3
In the same manner as in Example 1, but the conditions such as intermediate sintering were changed as shown in Table 7 below, Cu-W contacts and electric discharge machining electrodes of the following samples were produced. Moreover, the result of having measured the density about each obtained sample was combined with Table 7, and was shown.
[0053]
[Table 7]

[0054]
The density is the average value measured for each of the 50 samples in the same manner as in Example 1. The density was almost the same as the theoretical density even when the shape changed, and Cu was completely infiltrated into the pores of the molded body. I understand. Further, the cross-sectional structure of each sample was also free from defects, and Cu eluate was not seen at all on the surface where the dissolution inhibitor was applied.
[0055]
From this, the obtained composite alloy member of the present invention confirmed electrical conductivity, hardness and alloy structure in each part as an electrical contact, and confirmed similar characteristics in each part as an electrode for electric discharge machining. It was found that there was little variation in the characteristics at the level of n and n = 50, and sufficient characteristics were obtained. Also, the dimensions of each part are at a level that sufficiently satisfies the required accuracy, and processing other than the elution part is unnecessary.
[0056]
Example 4
A protective cover for the semiconductor device shown in FIG. 8 was prepared in the same manner as in Example 1, as in Example 1. However, Mo powder was used instead of W powder. That is, Mo powder having an average particle diameter of 3 μm and Ni powder having an average particle diameter of 4 μm were blended so as to be 99.9% by weight and 0.1% by weight, respectively, and mixed to obtain a mixed powder for molding. The following steps are the same as those in Example 1, but the intermediate sintering and other conditions were as shown in Table 8 below.
[0057]
[Table 8]

[0058]
Further, the density, thermal conductivity and coefficient of thermal expansion of the composite alloy member of each sample were measured and are shown in Table 9. In addition, about a density, it is an average value which measured 50 pieces for each sample, and it is almost according to a theoretical density, and it turns out that Cu infiltrated into the void | hole of a molded object completely. Moreover, the cross-sectional structure of each member was also free from defects, and Cu eluate was not seen at all on the surface where the dissolution inhibitor was applied.
[0059]
[Table 9]

[0060]
Further, for the composite alloy member of each sample, among the dimensional accuracy as a protective cover for a semiconductor device, a portion that requires particularly high accuracy in terms of characteristics, that is, the height and recess of the outer peripheral edge of the box-shaped member in FIG. The flatness of the bottom surface forming each was measured, and the dimensional variation was shown in Table 10. It can be seen that both satisfy the required accuracy.
[0061]
[Table 10]

[0062]
Example 5
Using the same W powder and Ni powder as in Example 1 and using Cu powder having an average particle diameter of 4 μm, a protective cover used as shown in FIG. That is, the amounts of W powder and Ni powder were 99.9% by weight and 0.1% by weight as in Example 1, and these powders and Cu powder were blended so as to have the composition shown in Table 11 below. The mixture was uniformly mixed to obtain a mixed powder for molding.
[0063]
Next, each mixed powder was subjected to pressure molding in the same manner as in Example 1 to produce a molded body shown in FIG. The mold used at this time is the same as in Example 1. After applying BN powder as an elution inhibitor to the entire surface excluding one surface including the convex portion 5 of the molded body shown in FIG. 4, the molded body was sintered in hydrogen gas at the temperatures shown in Table 11, respectively. The shape of each of the obtained sintered bodies was not greatly distorted or deformed compared to the shape of the original molded body. Moreover, the density of each obtained sintered compact was 98% or more.
[0064]
Residual BN powder on the surface of the sintered body was removed by liquid honing, and Cu residue eluted on one surface where BN powder was not applied was removed by planar polishing together with the convex portions to obtain a protective cover having the shape shown in FIG. . Further, some of the protective covers were re-pressurized in the same manner as in Example 1. About the composite alloy member of each protective cover produced as mentioned above, the composition is shown in Table 11 with the sintering temperature and the presence or absence of the pressurization method.
[0065]
[Table 11]

[0066]
The composite alloy member of each sample was measured for density, thermal conductivity, and thermal expansion coefficient, and the results are shown in Table 12. In addition, about the density, it is the average value which measured 50 pieces for each sample, and became a value substantially close to a theoretical density, and the void | hole was not recognized. Moreover, the cross-sectional structure of each member was also free from defects, and Cu eluate was not seen at all on the surface coated with the dissolution inhibitor.
[0067]
[Table 12]

[0068]
Furthermore, the dimensional accuracy of each protective cover produced as described above was measured and evaluated in the same manner as in Example 1. That is, the height of the outer peripheral edge of the box-shaped member of FIG. 3 and the flatness of the bottom surface forming the recess were measured, and the dimensional variation was shown in Table 13. It can be seen that both satisfy the required accuracy.
[0069]
[Table 13]

[0070]
Example 6
The semiconductor protective cover shown in FIG. 8 was prepared in the same manner as in Example 1 except that Ag was infiltrated instead of Cu. However, for the infiltration of Ag, the molded body of FIG. 4 coated with an elution inhibitor was placed on a silver plate having a thickness of 1.0 mm cut out to the same width and length as the one surface, and in a hydrogen atmosphere. Infiltration was performed in a continuous furnace.
[0071]
The same protective cover was prepared in the same manner as in Example 1 using Cr powder instead of W powder. That is, Cr powder having an average particle size of 3 μm was pressure-molded with a single-axis molding machine to obtain a molded body having the shape shown in FIG. The following steps are the same as in Example 1. Table 14 shows the alloy compositions of the obtained composite alloy members, together with the temperature of intermediate sintering, the elution inhibitor, and the presence or absence of repressurization.
[0072]
[Table 14]

[0073]
The density, thermal conductivity, and thermal expansion coefficient of each obtained composite alloy member are shown in Table 15, and the height of the outer peripheral edge and the flatness of the bottom surface forming the concave portion of the obtained box-shaped member in FIG. Table 16 shows the variation of the measured dimensions. In any case, the same effects of the present invention as in Examples 1 to 5 were obtained. Further, in order to improve the infiltration of Cu, Ni powder having an average particle diameter of 4 μm was blended so as to be 0.1% by weight with respect to 99.9% by weight of the Cr powder, and produced in the same manner as above. Similar results were obtained for the composite alloy members.
[0074]
[Table 15]

[0075]
[Table 16]

[0076]
【The invention's effect】
According to the present invention, the shape of the molded body is devised in the manufacture of a composite alloy member comprising a first component of Ag and / or Cu and at least one second component of W, Mo, Cr, and WC. Therefore, it is possible to obtain a molded body that is more uniform than the conventional one with high productivity, and therefore it is possible to reduce warpage or deformation of the infiltrated body or sintered body obtained from this molded body, and at the same time, using an elution inhibitor. Since elution of one component can be limited to a predetermined finishing position, a subsequent finishing process can be reduced, and an inexpensive and high-quality manufacturing method of a composite alloy member can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view of a stepped member made of a composite alloy member according to the present invention.
2 is a cross-sectional view of a molded body used for manufacturing the stepped shape member of FIG. 1. FIG.
FIG. 3 is a perspective view of a box-shaped member made of a composite alloy member according to the present invention.
4 is a cross-sectional view of a molded body used for manufacturing the box-shaped member of FIG. 3. FIG.
FIG. 5 is a schematic cross-sectional view showing a mold part of a uniaxial pressure molding machine used for producing a molded body.
FIG. 6 is a cross-sectional view showing an example of a complex-shaped composite alloy member manufactured by the method of the present invention.
FIG. 7 is a schematic sectional view showing a step of removing a part of a fired body by machining in the method of the present invention.
FIG. 8 is a schematic cross-sectional view of a semiconductor device provided with a protective cover of a box-shaped member.
FIG. 9 is a schematic cross-sectional view of a semiconductor device provided with a heat dissipation substrate of a stepped shape member.
FIG. 10 is a perspective view showing an example of chamfering.
FIG. 11 is a perspective view showing another example of chamfering.
FIG. 12 is a perspective view showing an example of R-part removal.
FIG. 13 is a perspective view showing another example of the R portion removal.
[Explanation of symbols]
1 Stepped shape member
2 buttocks
3 Protrusion
4a Molded body
4b Molded body
5 Convex
6 recess
7 Box-shaped member
8 mortar
9 upper arm
10 Shimojo
11 C surface
12 grooves
13 Small steps
14 Baked product
15 Chuck jig
16 Whetstone
17 Eluate
18 Protective cover
19 Substrate
20 Semiconductor chip
21 Heat dissipation board

Claims

Ａｇ及び／又はＣｕの第１成分と、Ｗ、Ｍｏ、Ｃｒ、及びＷＣの少なくとも１種の第２成分とからなる複合合金部材の製造方法であって、
(１ａ) 第２成分粉末を型押成形して、互いに平行な上面と下面を有し、その片方の面に一定の輪郭形状をなす凸部が形成され、他方の面の前記凸部とほぼ対応する位置に該凸部とほぼ同じ輪郭形状の凹部を有する成形体を得る工程と、
(１ｂ) 該成形体又は該成形体を焼成して得た多孔質焼結体において、その前記凸部又は凹部を設けた上面又は下面のいずれかを除く全ての面に、第１成分の溶出を防ぐ溶出防止剤を施す工程と、
(１ｃ) 該成形体又は多孔質焼結体の前記凸部又は凹部を設けた上面又は下面のうち溶出防止剤が施されていない面に第１成分を接触させた状態で、該第１成分を成形体又は多孔質焼結体の空孔に溶浸させて溶浸体を得る工程と、
(１ｄ) 該溶浸体の上面又は下面のうち溶出防止剤が施されていない面を溶出した第１成分と共に凸部又は凹部を含めて加工除去し、同時に又は前後してそれ以外の面の溶出防止剤残渣を除去する工程とを備えたことを特徴とする、前記複合合金部材の製造方法。A method for producing a composite alloy member comprising a first component of Ag and / or Cu and at least one second component of W, Mo, Cr, and WC,
(1a) The second component powder is embossed and has an upper surface and a lower surface that are parallel to each other, and a convex portion having a constant contour shape is formed on one surface thereof, and substantially the same as the convex portion on the other surface. A step of obtaining a molded body having a concave portion having substantially the same contour shape as the convex portion at a corresponding position;
(1b) In the porous sintered body obtained by firing the molded body or the molded body, the first component is eluted on all surfaces except the upper surface or the lower surface provided with the convex portion or the concave portion. Applying an anti-elution agent to prevent
(1c) The first component in a state where the first component is brought into contact with the upper surface or the lower surface of the molded body or the porous sintered body provided with the convex portion or the concave portion, to which the elution inhibitor is not applied. Infiltrating into the pores of the molded body or porous sintered body to obtain an infiltrated body,
(1d) The surface of the infiltrated body that is not subjected to the dissolution inhibitor is removed together with the first component that has been eluted, including the convex portion or the concave portion, and simultaneously or back and forth on the other surface. And a step of removing an elution inhibitor residue.

Ａｇ又はＣｕの第１成分と、Ｗ、Ｍｏ、Ｃｒ、ＷＣの少なくとも１種の第２成分とからなる複合合金部材の製造方法であって、
(２ａ) 第１成分粉末と第２成分粉末との混合粉末を型押成形して、互いに平行な上面と下面を有し、その片方の面に一定の輪郭形状をなす凸部が形成され、他方の面の前記凸部とほぼ対応する位置に該凸部とほぼ同じ輪郭形状の凹部を有する成形体を得る工程と、
(２ｂ) 該成形体の前記凸部又は凹部を設けた上面又は下面のいずれかを除く全ての面に、第１成分の溶出を防ぐ溶出防止剤を施す工程と、
(２ｃ) 該成形体を第１成分の融点以上の温度で焼成して焼結体とする工程と、
(２ｄ) 該焼結体の上面又は下面のうち溶出防止剤が施されていない面を溶出した第１成分と共に凸部又は凹部を含めて加工除去し、同時に又は前後してそれ以外の面の溶出防止剤残渣を除去する工程とを備えたことを特徴とする、前記複合合金部材の製造方法。A method for producing a composite alloy member comprising a first component of Ag or Cu and at least one second component of W, Mo, Cr, and WC,
(2a) A mixed powder of the first component powder and the second component powder is embossed to have an upper surface and a lower surface parallel to each other, and a convex portion having a constant contour shape is formed on one surface thereof, Obtaining a molded body having a concave portion having substantially the same contour shape as the convex portion at a position substantially corresponding to the convex portion on the other surface;
(2b) applying an elution inhibitor that prevents elution of the first component to all surfaces except either the upper surface or the lower surface provided with the convex portion or the concave portion of the molded body;
(2c) firing the molded body at a temperature equal to or higher than the melting point of the first component to obtain a sintered body;
(2d) Of the upper surface or lower surface of the sintered body, the surface that has not been subjected to the elution inhibitor is removed together with the first component that has been eluted, including the convex portion or the concave portion, and at the same time or before and after, And a step of removing an elution inhibitor residue.

前記第１成分粉末と第２成分粉末の合計に対して１重量％以下の鉄族元素の粉末を添加して用いることを特徴とする、請求項１又は２に記載の複合合金部材の製造方法。3. The method for producing a composite alloy member according to claim 1, wherein an iron group element powder of 1 wt% or less is added to the total of the first component powder and the second component powder. .

溶浸体又は焼結体中の第１成分の含有量が５〜４０重量％であることを特徴とする、請求項１〜３のいずれかに記載の複合合金部材の製造方法。The method for producing a composite alloy member according to any one of claims 1 to 3, wherein the content of the first component in the infiltrated body or the sintered body is 5 to 40% by weight.

前記溶出防止剤が、焼成時に第１又は第２成分と反応せず、溶融した第１成分と濡れない金属の酸化物、窒化物、又は炭化物であることを特徴とする、請求項１〜４のいずれかに記載の複合合金部材の製造方法。The said elution inhibitor is a metal oxide, nitride, or carbide which does not react with the first or second component during firing and does not wet with the molten first component. The manufacturing method of the composite alloy member in any one of.

前記(１ａ)又は(２ａ)の粉末成形工程において、上１段及び下１段の杵を用いた一軸加圧により成形することを特徴とする、請求項１又は２に記載の複合合金部材の製造方法。3. The composite alloy member according to claim 1, wherein in the powder forming step of (1a) or (2a), the composite alloy member is formed by uniaxial pressurization using upper and lower tiers of wrinkles. Production method.