JP4138844B2 - Cr-Cu alloy, manufacturing method thereof, heat sink for semiconductor, and heat dissipation component for semiconductor - Google Patents
Cr-Cu alloy, manufacturing method thereof, heat sink for semiconductor, and heat dissipation component for semiconductor Download PDFInfo
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本発明は、電子機器に搭載された半導体素子等の発熱体から発生する熱を速やかに放散させるために用いられ、低い熱膨張率と高い熱伝導率を要求される半導体用放熱板（すなわちヒートシンク材またはヒートスプレッダー材）や半導体用放熱部品、ならびにその素材となるCr−Cu合金およびその製造方法に関するものである。
なお、ここでは半導体用放熱板と半導体用放熱部品を総称して放熱用材料と記す。
The present invention is used to quickly dissipate heat generated from a heating element such as a semiconductor element mounted on an electronic device, and is used for a semiconductor heat sink (that is, a heat sink) that requires low thermal expansion coefficient and high thermal conductivity. The present invention relates to a heat radiating component for a semiconductor or a heat spreader material, a semiconductor heat radiating component, a Cr—Cu alloy used as the material, and a manufacturing method thereof.
Note that, here, the semiconductor heat dissipation plate and the semiconductor heat dissipation component are collectively referred to as a heat dissipation material.
半導体素子等の電子部品を搭載した電子機器を作動させる際には、電子回路への通電に伴い電子部品が発熱する。電子機器の高出力化に伴い、作動時の発熱量はますます増加する傾向にあるが、温度が上昇し過ぎると半導体素子の特性が変化し、電子機器の動作が不安定になる問題が生じる。また長時間にわたって使用することによって過剰な高温に曝されると、電子部品の接合材（たとえばハンダ等）や絶縁材（たとえば合成樹脂等）が変質して、電子機器の故障の原因になる。そのため、電子部品から発熱する熱を速やかに放散させる必要がある。そこで、放熱用材料を介して熱を放散させる技術が種々検討されている。 When an electronic device equipped with an electronic component such as a semiconductor element is operated, the electronic component generates heat as the electronic circuit is energized. As the output of electronic equipment increases, the amount of heat generated during operation tends to increase. However, if the temperature rises too much, the characteristics of the semiconductor element change and the operation of the electronic equipment becomes unstable. . Further, when exposed to an excessively high temperature after being used for a long period of time, a bonding material (for example, solder) or an insulating material (for example, synthetic resin) of an electronic component is altered, causing a failure of the electronic device. Therefore, it is necessary to quickly dissipate the heat generated from the electronic component. Therefore, various techniques for dissipating heat through a heat dissipation material have been studied.
半導体素子は、放熱用材料に直接、あるいはたとえば窒化アルミニウム（AlＮ）にAl電極をダイレクトボンディングした基板（いわゆるＤＢＡ基板）上にハンダ付けあるいはロウ付けされた後、放熱用材料の上に同様の方法により固定される。その際、ＤＢＡ基板の熱膨張率は５〜７×10-6Ｋ-1であるため、接合される放熱用材料としてはこれに近い熱膨張率を有することが要求される。現在使用されている放熱用材料としては、Ｗ−Cu系複合材料の熱膨張率が６〜９×10-6Ｋ-1であり、Mo−Cu系複合材料の熱膨張率が７〜14×10-6Ｋ-1である。このように接合される相手材に近い熱膨張率を有することにより、半導体素子の発熱によって発生する熱応力の影響を小さく抑えることができる。 A semiconductor element is soldered or brazed directly onto a heat dissipation material or onto a substrate (so-called DBA substrate) in which an Al electrode is directly bonded to, for example, aluminum nitride (AlN), and then a similar method is applied on the heat dissipation material. It is fixed by. At that time, since the DBA substrate has a thermal expansion coefficient of 5 to 7 × 10 −6 K −1 , the heat dissipation material to be joined is required to have a thermal expansion coefficient close to this. As heat dissipation materials currently used, the thermal expansion coefficient of W-Cu composite materials is 6-9 × 10 −6 K −1 , and the thermal expansion coefficient of Mo—Cu composite materials is 7-14 ×. 10 −6 K −1 . By having a coefficient of thermal expansion close to that of the counterpart material to be joined in this way, it is possible to suppress the influence of thermal stress generated by heat generation of the semiconductor element.
放熱用材料は、熱膨張が少ないことに加えて、熱伝導率が大きいことが要求されるが、両者を同時に達成することは難しい。そのため、熱膨張率の小さい材料と熱伝導率の大きい材料を組み合わせた複合材料が多く用いられている。
このような例として、たとえば特許文献１には、Ｗ−Cu，Mo−Cu等の金属−金属系複合材料が提案されている。Ｗ，Moは熱膨張率が低く、他方、Cuは熱伝導率が高いという特性を利用する技術である。
The heat dissipation material is required to have high thermal conductivity in addition to low thermal expansion, but it is difficult to achieve both at the same time. For this reason, a composite material in which a material having a low coefficient of thermal expansion and a material having a high thermal conductivity are combined is often used.
As such an example, for example, Patent Document 1 proposes a metal-metal composite material such as W-Cu and Mo-Cu. W and Mo are technologies that utilize the characteristic that the coefficient of thermal expansion is low, while Cu is high in thermal conductivity.
また特許文献２には、SiＣ−Al，Cu2Ｏ−Cu等のセラミックス−金属系の複合材料が開示されている。
さらに特許文献３にはCr−Cu，Nb−Cu等の金属−金属系複合材料が開示されている。この技術は、鋳造した後で熱間圧延し、さらに冷間圧延して所定の形状を得てから溶体化熱処理し、時効熱処理を行なってCuマトリックス中から粒子状Cr相を析出させ、それによって熱膨張率の低減を図るものである。特許文献３は、Cr−Cu系合金について、低熱膨張率と高熱伝導率を共に達成するための技術である。この技術は、２〜50質量％のCrを含有するCu合金について、第２相として存在する凝固の際に析出する初晶Cr相のアスペクト比を10以上とすることによって、複合則から予想されるよりも低い熱膨張率を得ることが可能になるというものである。しかしながら、製造方法は溶解鋳造法を前提としているので、開示されている方法ではCr含有量が増加すると、融点が高くなる上、凝固偏析により均質な合金製造が困難である。これを均質化するためには、高温長時間の均質化熱処理に加えて、熱間鍛造や熱間圧延工程が必要となる。したがって、特許文献３の実施例には、30質量％を超えるCrを含有する例は開示されていない。しかしながら、この方法では凝固の際の１次析出相であるCr相のアスペクト比を100以上として、やっと複合則より10％程度の熱膨張率低下が得られる程度である。Cr相のアスペクト比を100とするだけでも、たとえば冷間圧延では90％以上の圧下を必要とする。その結果、製造コストの上昇を招き、しかも製品として提供できる放熱用材料の寸法が制限されるという問題がある。
Further, Patent Document 3 discloses metal-metal composite materials such as Cr—Cu and Nb—Cu. This technology involves hot rolling after casting, and further cold rolling to obtain a predetermined shape, followed by solution heat treatment, and aging heat treatment to precipitate a particulate Cr phase from the Cu matrix, thereby This is intended to reduce the coefficient of thermal expansion. Patent Document 3 is a technique for achieving both a low thermal expansion coefficient and a high thermal conductivity for a Cr—Cu alloy. This technology is expected from the composite law by setting the aspect ratio of the primary Cr phase that precipitates during solidification existing as the second phase to 10 or more for Cu alloys containing 2 to 50 mass% of Cr. It is possible to obtain a lower coefficient of thermal expansion than the above. However, since the production method is premised on the melt casting method, when the Cr content increases, the melting point increases and the production of a homogeneous alloy is difficult due to solidification segregation. In order to homogenize this, a hot forging or hot rolling process is required in addition to the high temperature and long time homogenization heat treatment. Therefore, the example of Patent Document 3 does not disclose an example containing Cr exceeding 30% by mass. However, with this method, when the aspect ratio of the Cr phase, which is the primary precipitation phase during solidification, is 100 or more, a thermal expansion coefficient reduction of about 10% is finally obtained from the composite law. Even if the aspect ratio of the Cr phase is only 100, for example, cold rolling requires a reduction of 90% or more. As a result, there is a problem in that the manufacturing cost is increased and the size of the heat dissipating material that can be provided as a product is limited.
非特許文献１には、30質量％以上のCrを含むCr−Cu合金を溶解と冷間加工によって均一に製造する技術が開示されている。すなわち、CrとCuの混合粉末を焼結したものを消耗電極として用い、高価なアーク放電を用いた溶解鋳造法で鋳造し、さらに室温での延性が不十分なCrが変形し易いように押出し法によって丸棒を製造する方法である。押出し法は、Crに対してCuマトリックスからの静水圧が働くため、加工が容易となることを利用したものである。この技術では経済性に問題があり、かつ放熱材料のような薄い板状の材料の製造には適していない。 Non-Patent Document 1 discloses a technique for uniformly producing a Cr—Cu alloy containing 30 mass% or more of Cr by melting and cold working. In other words, a sintered powder of mixed powder of Cr and Cu is used as a consumable electrode, cast by melt casting using expensive arc discharge, and extruded so that Cr with insufficient ductility at room temperature is easily deformed. It is a method of manufacturing a round bar by the method. The extrusion method utilizes the fact that processing is easy because the hydrostatic pressure from the Cu matrix acts on Cr. This technique has a problem in economy and is not suitable for manufacturing a thin plate-like material such as a heat dissipation material.
非特許文献２には、15質量％のCrを含み、20μｍ程度の微細Cr相を析出させたCr−Cu合金に対し、冷間で強加工を施すことにより、低い熱膨張率を達成する技術が開示されている。この技術では、Cr相を１μｍほどの厚さとなるまで強加工を行なう必要があり、経済性に問題がある。また、たとえば30質量％以上のCrを含む場合に、このような強加工を行なうことは困難であると考えられる。
Non-Patent
また発明者らは、特許文献４に、熱処理によって熱膨張率を調整したCr−Cu材を放熱用材料に適用する技術を開示している。特許文献４に開示した粉末冶金法では、Cr粉末を使用し、Cuと焼結あるいは溶浸を行なって合金化し、同様に時効熱処理を行なってCrマトリックス中から粒子状Cr相の析出を図るものである。これらの方法では、粒子状Cr相の析出は３次元でランダムであり、どの方向に対しても膨張率は一定である。一方、半導体用放熱材料では、一般的に薄板形状が多く、この場合、板面上に半導体が接合されるので、半導体の接合部を含む面、つまり板の面内の方向の熱膨張率を小さくすることが要求される。 In addition, the inventors disclose a technique in which a Cr—Cu material whose thermal expansion coefficient is adjusted by heat treatment is applied to a heat dissipation material in Patent Document 4. In the powder metallurgy method disclosed in Patent Document 4, Cr powder is used, alloyed by sintering or infiltration with Cu, and similarly subjected to aging heat treatment to precipitate particulate Cr phase from the Cr matrix. It is. In these methods, the precipitation of the particulate Cr phase is random in three dimensions, and the expansion coefficient is constant in any direction. On the other hand, semiconductor heat-dissipating materials generally have many thin plate shapes. In this case, since the semiconductor is bonded onto the plate surface, the coefficient of thermal expansion in the direction including the semiconductor junction, that is, in the direction of the plate surface, is increased. It is required to be small.
また、特許文献４に開示されたCr−Cu材では、微細析出物の析出形態を制御することのみで、熱膨張率を低減させる技術であるため、ロウ付け接合のような750℃以上の高温に加熱する接合方法では、微細析出物が変化してしまう惧れがあり、低い熱膨張率が安定して得られない。
本発明は上記のような問題を解消し、面内の方向の熱膨張率が小さく、かつ熱伝導率が大きく、さらに高温に加熱する接合の後も低い熱膨張率を保持し、しかも加工性に優れたCr−Cu合金とその製造方法を提供し、さらに、そのCr−Cu合金を用いた半導体用放熱板と半導体用放熱部品を提供することを目的とする。
つまり本発明は、放熱用材料（すなわち半導体用放熱板，半導体用放熱部品）に要求される種々の形状、特に板状の製品あるいはプレス成形用の素材を提供するものであり、Crの原料として粉末を使用することによって、従来の溶解鋳造法では均質な材料の製造が容易ではない組成の放熱用材料に対して経済的に放熱用材料を製造するものである。さらに本発明では、Cr粉末の焼結体にCuを溶浸させた溶浸体に冷間圧延を施すという新規の工程を採用することによって、熱膨張率をさらに低減した材料を製造するものである。
The present invention solves the above-mentioned problems, has a low coefficient of thermal expansion in the in-plane direction, has a high thermal conductivity, and retains a low coefficient of thermal expansion even after bonding heated to a high temperature. An object of the present invention is to provide an excellent Cr—Cu alloy and a method for producing the same, and to provide a semiconductor heat dissipation plate and a semiconductor heat dissipation component using the Cr—Cu alloy.
In other words, the present invention provides various shapes required for heat-dissipating materials (that is, heat-dissipating plates for semiconductors and heat-dissipating parts for semiconductors), in particular, plate-shaped products or materials for press molding. By using the powder, the heat dissipation material is economically manufactured with respect to the heat dissipation material having a composition in which it is not easy to manufacture a homogeneous material by the conventional melting and casting method. Furthermore, in the present invention, by adopting a new process of cold rolling the infiltrated body in which Cu is infiltrated into the sintered body of Cr powder, a material having a further reduced thermal expansion coefficient is manufactured. is there.
Cr−Cu合金の熱膨張率は、下記の(1)式で表わされる複合則に従うことが知られている（特許文献３参照）。
αalloy ＝αCr×ＶCr＋αCu×（１−ＶCr） ・・・(1)
αalloy：Cr−Cu合金の熱膨張率
αCr ：Crの熱膨張率
αCu ：Cuの熱膨張率
ＶCr ：Crの体積分率
ただし、実際には(1)式のような単純な相加平均には従わず、(1)式から予測されるより大きい値になるようなモデルが多く提案されている。たとえばGermanらのモデルが知られている（R.M.German et al. Int. J. Powder Metall, vol.30(1994),p205）。
It is known that the thermal expansion coefficient of the Cr—Cu alloy follows a composite rule represented by the following formula (1) (see Patent Document 3).
α alloy = α Cr × V Cr + α Cu × (1-V Cr ) (1)
α alloy : Thermal expansion coefficient of Cr-Cu alloy α Cr : Thermal expansion coefficient of Cr α Cu : Thermal expansion coefficient of Cu V Cr : Volume fraction of Cr However, in reality, it is a simple phase like the equation (1) Many models have been proposed that do not follow the arithmetic mean, but have a larger value predicted from the equation (1). For example, the German model is known (RM German et al. Int. J. Powder Metall, vol. 30 (1994), p205).
公表されている純Crの熱膨張率のデータはばらつきが大きく、Cr−Cu合金の熱膨張率を正確に予測するのは難しいが、(1)式に従うとした場合、放熱用材料として好適な低熱膨張率（たとえば13×10-6Ｋ-1）を得るためのCr含有量がＶCr値から算出でき、その計算値は30質量％以上となる。このようなCrを30質量％以上含有するCr−Cu合金を製造する際には、従来の溶解鋳造法ではアーク放電等の特殊な方法を採用する必要があり、製造コストの上昇は避けられない。 The published data on the thermal expansion coefficient of pure Cr vary widely, and it is difficult to accurately predict the thermal expansion coefficient of Cr-Cu alloys. The Cr content for obtaining a low coefficient of thermal expansion (for example, 13 × 10 −6 K −1 ) can be calculated from the V Cr value, and the calculated value is 30% by mass or more. When producing such a Cr-Cu alloy containing 30% by mass or more of Cr, it is necessary to adopt a special method such as arc discharge in the conventional melting casting method, and an increase in production cost is inevitable. .
これに対して発明者らは、Crの含有量を広範囲にわたって調整可能な粉末冶金法を採用し、Cr粉末単独あるいはCr粉末とCu粉末を混合し焼結した後、Cuを溶浸する技術を開発した。Cuを溶浸する工程は、Cr粉末を単独で焼結し、多孔質体とした場合には必須であるが、Cr粉末とCu粉末を混合して焼結する場合には必ずしも必要ではない。Cr焼結体（すなわち多孔質体）またはCr−Cu焼結体にCuを溶浸させることにより、30質量％超え80質量％以下のCrを均一に分布させたCr−Cu合金を容易に製造することが可能となる。 On the other hand, the inventors adopt a powder metallurgy method in which the Cr content can be adjusted over a wide range, Cr powder alone or a mixture of Cr powder and Cu powder and sintering, and then infiltrating Cu. developed. The step of infiltrating Cu is essential when Cr powder is sintered alone to form a porous body, but is not necessarily required when Cr powder and Cu powder are mixed and sintered. By infiltrating Cu into a Cr sintered body (ie porous body) or Cr-Cu sintered body, a Cr-Cu alloy in which Cr of more than 30% by mass and 80% by mass or less is uniformly distributed is easily manufactured. It becomes possible to do.
発明者らは、このような溶浸体に冷間圧延で10％以上の圧下を加え、必要に応じて熱処理を施すことによって、面内の方向の小さい熱膨張率を得ることが可能であるという知見を得た。つまり、溶浸体に必要により均質化および時効のための熱処理（以下、均質化時効熱処理という）を300〜1050℃で行なった後、冷間圧延で10％以上の圧下を付与し、さらに必要に応じて軟質化および時効のための熱処理（以下、軟質化時効熱処理という）を300〜900℃で行なうことによって、面内の方向の熱膨張率の大幅な低減を達成できることを見出した。 The inventors can obtain a small coefficient of thermal expansion in the in-plane direction by applying a reduction of 10% or more to such an infiltrated body by cold rolling and performing a heat treatment as necessary. I got the knowledge. In other words, if necessary, heat treatment for homogenization and aging (hereinafter referred to as homogenization aging heat treatment) is performed on the infiltrated body at 300 to 1050 ° C., and then cold rolling is applied to at least 10% reduction. Accordingly, it has been found that by performing heat treatment for softening and aging (hereinafter referred to as softening aging heat treatment) at 300 to 900 ° C., a significant reduction in the coefficient of thermal expansion in the in-plane direction can be achieved.
冷間圧延前後の熱処理により、Cuマトリックス中に微細な粒子状Cr相が析出する。析出させる粒子状Cr相は、長径が100ｎｍ以下で、アスペクト比が10未満のものの密度が20個／μｍ2以上であることが熱膨張率低減の観点から好ましい。
ここでいう粒子状Cr相の数は、以下の方法で決定される。すなわち１〜５kVの低加速電圧による走査型電子顕微鏡（いわゆるＳＥＭ）観察を１万倍〜30万倍程度で行ない、視野中に見えるCr相の数から密度（個／μｍ2）を算出する。
A fine particulate Cr phase precipitates in the Cu matrix by heat treatment before and after cold rolling. The particulate Cr phase to be precipitated preferably has a major axis of 100 nm or less and an aspect ratio of less than 10 and a density of 20 / μm 2 or more from the viewpoint of reducing the thermal expansion coefficient.
The number of particulate Cr phases here is determined by the following method. That is, scanning electron microscope (so-called SEM) observation with a low acceleration voltage of 1 to 5 kV is performed at about 10,000 to 300,000 times, and the density (pieces / μm 2 ) is calculated from the number of Cr phases visible in the visual field.
観察に用いるサンプルは、以下のような方法でエッチングを行なってから実施する。すなわち、蒸留水80mlに対し、２クロム酸カリウム10ｇ，硫酸（96質量％）５ml，塩酸（37質量％）１〜２滴を溶解混合した溶液中に、室温で３〜15秒浸漬後、水洗乾燥を行なうことで、微細なCr相の観察が可能となる。
焼結したままの素材や溶浸したままの素材を用いる方法は、さらに切削等の加工が必要であるので、様々な形状が要求される多品種少量生産には適していない。これに対して本発明のCr−Cu合金は、様々な厚さの板形状への加工が容易であり、プレス加工による打ち抜きにも適用できるので、大量生産のみならず、多品種少量生産にも対応できる。
The sample used for observation is performed after etching by the following method. That is, in 80 ml of distilled water, 10 g of potassium dichromate, 5 ml of sulfuric acid (96 mass%), and 1 to 2 drops of hydrochloric acid (37 mass%) were dissolved and mixed at room temperature for 3 to 15 seconds, followed by washing with water. By performing drying, it becomes possible to observe a fine Cr phase.
The method using a raw material that has been sintered or a material that has been infiltrated requires further processing such as cutting, and thus is not suitable for high-mix low-volume production that requires various shapes. On the other hand, the Cr-Cu alloy of the present invention can be easily processed into plate shapes with various thicknesses, and can be applied to stamping by press working. Yes.
補足であるが、本発明のCr−Cu合金では、溶浸体を製造する段階で空隙が残留する惧れがあるが、冷間圧延を行なうことによって空隙が押し潰されて密着する。その結果、空隙の存在に起因する熱伝導率の低下も防止できる。
すなわち本発明は、Cuマトリックスと偏平したCr相からなる粉末冶金で得られたCr−Cu合金であって、Cr−Cu合金中のCr含有量が30質量％超え80質量％以下であり、偏平したCr相の平均アスペクト比が1.0超え100未満であるCr−Cu合金である。
As a supplement, in the Cr-Cu alloy of the present invention, there is a possibility that voids remain at the stage of manufacturing the infiltrant, but the voids are crushed and closely adhered by performing cold rolling. As a result, a decrease in thermal conductivity due to the presence of voids can also be prevented.
That is, the present invention is a Cr-Cu alloy obtained by powder metallurgy comprising a Cu matrix and a flat Cr phase, wherein the Cr content in the Cr-Cu alloy is more than 30% by mass and 80% by mass or less. The Cr-Cu alloy has an average aspect ratio of Cr phase exceeding 1.0 and less than 100.
本発明のCr−Cu合金においては、偏平したCr相の密度がCr−Cu合金の厚み方向の１mmあたり200個以下であることが好ましい。
また本発明のCr−Cu合金においては、Cuマトリックス中に、長径が100ｎｍ以下でアスペクト比が10未満の粒子状Cr相が析出し、粒子状Cr相の密度が20個／μｍ2 以上であることが好ましい。
In the Cr—Cu alloy of the present invention, the density of the flat Cr phase is preferably 200 or less per 1 mm in the thickness direction of the Cr—Cu alloy.
In the Cr—Cu alloy of the present invention, a particulate Cr phase having a major axis of 100 nm or less and an aspect ratio of less than 10 is precipitated in the Cu matrix, and the density of the particulate Cr phase is 20 particles / μm 2 or more. It is preferable.
また本発明は、上記のCr−Cu合金を使用した半導体用放熱板あるいは半導体用放熱部品である。
また本発明は、Cr含有量が30質量％超え80質量％以下であり、残部がCuおよび不可避的不純物からなるCr−Cu合金を冷間圧延で10％以上の圧下を加えることにより、Cr相の平均アスペクト比が1.0超え100未満とするCr−Cu合金の製造方法である。
Moreover, this invention is a heat sink for semiconductors or a heat sink component for semiconductors using said Cr-Cu alloy.
Further, the present invention provides a Cr phase by applying a reduction of 10% or more by cold rolling to a Cr-Cu alloy having a Cr content of more than 30% by mass and 80% by mass or less, and the balance being Cu and inevitable impurities. This is a method for producing a Cr—Cu alloy having an average aspect ratio of more than 1.0 and less than 100.
本発明のCr−Cu合金の製造方法においては、Crの原料としてCr粉末を使用することが好ましい。
さらに本発明は、Cr粉末を焼結して多孔質体とした後、多孔質体にCuを溶浸して、Cr含有量を30質量％超え80質量％以下とした溶浸体を得る焼結溶浸工程と、溶浸体に冷間圧延で10％以上の圧下を加えて圧延材を得る圧延工程とを有するCr−Cu合金の製造方法である。なお、多孔質体とは、多孔質状の焼結体を指し、溶浸体とは、多孔質体の気孔（空隙）にCuを溶浸させたもの、およびCr粉末とCu粉末を混合して焼結したCuマトリックス中にCr相が存在するものを指す。
また本発明は、Cr粉末を焼結して多孔質体とした後、多孔質体にCuを溶浸して、Cr含有量を30質量％超え80質量％以下とした溶浸体を得る焼結溶浸工程と、溶浸体に冷間圧延で10％以上の圧下を加えて圧延材を得る圧延工程と、圧延材を300〜900℃の温度範囲で加熱する熱処理工程とを有するCr−Cu合金の製造方法である。
In the method for producing a Cr—Cu alloy of the present invention, it is preferable to use Cr powder as a raw material of Cr.
Furthermore, the present invention sinters Cr powder to obtain a porous body, and then infiltrates Cu into the porous body to obtain an infiltrated body in which the Cr content exceeds 30 mass% and is 80 mass% or less. and infiltration process, a method for producing a Cr-Cu alloy and a rolling step to obtain a rolled material by adding pressure of more than 10% by cold rolling the infiltrated body. The porous body refers to a porous sintered body, and the infiltrated body refers to a mixture of porous body pores (voids) infiltrated with Cu, and Cr powder and Cu powder. This refers to the presence of a Cr phase in a sintered Cu matrix.
In addition, the present invention sinters Cr powder to form a porous body, and then infiltrates Cu into the porous body to obtain an infiltrated body in which the Cr content exceeds 30% by mass and is 80% by mass or less. Cr-Cu having an infiltration process, a rolling process for obtaining a rolled material by applying a reduction of 10% or more to the infiltrated body by cold rolling, and a heat treatment process for heating the rolled material in a temperature range of 300 to 900 ° C. It is a manufacturing method of an alloy.
また本発明は、Cr粉末とCu粉末を混合して焼結しCr含有量を30質量％超え80質量％以下とした溶浸体を得る焼結溶浸工程と、溶浸体に冷間圧延で10％以上の圧下を加えて圧延材を得る圧延工程とを有するCr−Cu合金の製造方法である。この発明では、焼結と溶浸を一つの工程で行なう。
また本発明は、Cr粉末とCu粉末を混合して焼結しCr含有量を30質量％超え80質量％以下とした溶浸体を得る焼結溶浸工程と、溶浸体に冷間圧延で10％以上の圧下を加えて圧延材を得る圧延工程と、圧延材を300〜900℃の温度範囲で加熱する熱処理工程とを有するCr−Cu合金の製造方法である。この発明では、焼結と溶浸を一つの工程で行なう。
また本発明は、Cr粉末とCu粉末を混合して焼結し、さらにCuを溶浸することでCr含有量を30質量％超え80質量％以下とした溶浸体を得る焼結溶浸工程と、溶浸体に冷間圧延で10％以上の圧下を加えて圧延材を得る圧延工程とを有するCr−Cu合金の製造方法である。
また本発明は、Cr粉末とCu粉末を混合して焼結し、さらにCuを溶浸することでCr含有量を30質量％超え80質量％以下とした溶浸体を得る焼結溶浸工程と、溶浸体に冷間圧延で10％以上の圧下を加えて圧延材を得る圧延工程と、圧延材を300〜900℃の温度範囲で加熱する熱処理工程とを有するCr−Cu合金の製造方法である。
The present invention also includes a sintering infiltration process in which Cr powder and Cu powder are mixed and sintered to obtain an infiltrant having a Cr content of more than 30% by mass and less than 80% by mass; by adding 10% or greater reduction in the rolling is a manufacturing method of the Cr-Cu alloy and a rolling step to obtain a rolled material. In the present invention, it row by sintering and infiltration one step.
The present invention also includes a sintering infiltration process in which Cr powder and Cu powder are mixed and sintered to obtain an infiltrant having a Cr content of more than 30% by mass and 80% by mass or less, and cold rolling to the infiltrated body Is a method for producing a Cr—Cu alloy having a rolling step of applying a reduction of 10% or more to obtain a rolled material and a heat treatment step of heating the rolled material in a temperature range of 300 to 900 ° C. In the present invention, sintering and infiltration are performed in one step.
In addition, the present invention is a sintering infiltration process in which Cr powder and Cu powder are mixed and sintered, and further infiltrated with Cu to obtain an infiltrated body having a Cr content of more than 30% by mass and 80% by mass or less. And a rolling process for obtaining a rolled material by applying a reduction of 10% or more to the infiltrated body by cold rolling.
In addition, the present invention is a sintering infiltration process in which Cr powder and Cu powder are mixed and sintered, and further infiltrated with Cu to obtain an infiltrated body having a Cr content of more than 30% by mass and 80% by mass or less. A Cr-Cu alloy comprising: a rolling process for obtaining a rolled material by applying a reduction of 10% or more to the infiltrated body by cold rolling; and a heat treatment process for heating the rolled material in a temperature range of 300 to 900 ° C. Is the method.
これらの溶浸体は、300〜1050℃の温度範囲で加熱した後、冷間圧延を行なうことが好ましい。
なお本発明のCr−Cu合金は、偏平なCr相と、わずかにCrを含有するCu相（すなわちCuマトリックス）とからなる、いわゆるCr−Cu複合材料である。
These infiltrates are preferably subjected to cold rolling after heating in a temperature range of 300 to 1050 ° C.
The Cr—Cu alloy of the present invention is a so-called Cr—Cu composite material composed of a flat Cr phase and a Cu phase containing a slight amount of Cr (ie, a Cu matrix).
本発明によれば、面内の方向の熱膨張率が小さく、かつ熱伝導率が大きく、さらに高温に加熱する接合の後も低い熱膨張率を保持し、しかも加工性に優れたCr−Cu合金を製造でき、さらに、そのCr−Cu合金を用いた半導体用放熱板と半導体用放熱部品を製造できる。 According to the present invention, the coefficient of thermal expansion in the in-plane direction is small, the thermal conductivity is large, and a low thermal expansion coefficient is maintained even after bonding heated to a high temperature, and excellent in workability. An alloy can be manufactured, and furthermore, a semiconductor heat dissipation plate and a semiconductor heat dissipation component using the Cr-Cu alloy can be manufactured.
まず、本発明におけるCr含有量の限定理由を説明する。
Crは、本発明のCr−Cu合金において、熱膨張率の低減を達成するための重要な元素である。Cr含有量が30質量％以下では、放熱用材料（すなわち半導体用放熱板，半導体用放熱部品）に要求される低熱膨張率（約14×10-6Ｋ-1以下）が得られない。一方、80質量％を超えると、熱伝導率が低下し、放熱用材料として十分な放熱効果が得られない。したがって、Crは30質量％超え80質量％以下とする。好ましくは40質量％以上70質量％以下である。なお、より好ましくは45質量％以上65質量％以下であり、50質量％超え65質量％以下が一層好ましい。
First, the reason for limiting the Cr content in the present invention will be described.
Cr is an important element for achieving a reduction in the coefficient of thermal expansion in the Cr—Cu alloy of the present invention. When the Cr content is 30% by mass or less, the low coefficient of thermal expansion (about 14 × 10 −6 K −1 or less) required for a heat radiating material (that is, a semiconductor heat radiating plate or a semiconductor heat radiating component) cannot be obtained. On the other hand, if it exceeds 80% by mass, the thermal conductivity is lowered, and a sufficient heat dissipation effect as a heat dissipation material cannot be obtained. Therefore, Cr is more than 30% by mass and 80% by mass or less. Preferably they are 40 mass% or more and 70 mass% or less. More preferably, it is 45% by mass or more and 65% by mass or less, and more preferably more than 50% by mass and 65% by mass or less.
本発明の特徴は、Crの原料をCr粉末として粉末冶金法を適用する点にある。粉末冶金法の採用によって、Cr粉末を用い、これを単独で、あるいはCu粉末と混合して焼結した焼結体に必要に応じてCuを溶浸させることによって、30質量％を超えるCrを均一に分布させたCr−Cu合金の製造が可能になった。
使用するCr粉末は、純度99質量％以上、ＪＩＳ規格Z2510:2004に準拠して篩分けした粒度10〜250μｍ（ＪＩＳ規格Z8801-1:2006に規定される公称目開き寸法）が好ましい。ただし、粒度が大きくなると、粉末を均一に充填することが困難になるほか、圧延後に板厚方向で十分な熱伝導率が得られ難いという傾向がある。また、粒度が小さくなるとCr粉末の表面積が増大して酸化し易くなり、焼結体（多孔質体）にCuを溶浸することが困難になる上、酸素含有量が増加して、後述するように加工性にも悪影響を及ぼす傾向がある。したがって、より好ましい粒度は30〜250μｍであり、50〜200μｍが一層好ましい。
A feature of the present invention resides in that a powder metallurgy method is applied using Cr raw material as Cr powder. By adopting the powder metallurgy method, Cr powder is used alone, or mixed with Cu powder and sintered into the sintered body as necessary to infiltrate Cu as necessary, so that Cr exceeding 30% by mass can be obtained. The production of uniformly distributed Cr-Cu alloys has become possible.
The Cr powder to be used preferably has a purity of 99% by mass or more and a particle size of 10 to 250 μm (nominal opening size defined in JIS standard Z8801-1: 2006) sieved according to JIS standard Z2510: 2004. However, when the particle size becomes large, it becomes difficult to uniformly fill the powder, and it is difficult to obtain sufficient thermal conductivity in the plate thickness direction after rolling. In addition, when the particle size is reduced, the surface area of the Cr powder increases and it becomes easy to oxidize, it becomes difficult to infiltrate Cu into the sintered body (porous body), and the oxygen content increases, which will be described later. As such, the workability tends to be adversely affected. Therefore, a more preferable particle size is 30 to 250 μm, and more preferably 50 to 200 μm.
また、Cr粉末中の不純物は、溶浸体の加工性向上の観点から、可能な限り低減することが好ましい。特にＯ，Ｎ，Ｃは多大な影響を及ぼし、大きい加工を施す場合には、Ｏ含有量を0.15質量％以下，Ｎ含有量を0.1質量％以下，Ｃ含有量を0.1質量％以下とすることが好ましい。より好ましくは、Ｏ含有量：0.08質量％以下，Ｎ含有量：0.03質量％以下，Ｃ含有量：0.03質量％以下である。 Further, impurities in the Cr powder are preferably reduced as much as possible from the viewpoint of improving the workability of the infiltrated body. In particular, O, N, and C have a great influence, and when performing large processing, the O content should be 0.15 mass% or less, the N content should be 0.1 mass% or less, and the C content should be 0.1 mass% or less. Is preferred. More preferably, the O content is 0.08 mass% or less, the N content is 0.03 mass% or less, and the C content is 0.03 mass% or less.
Cu粉末は、工業的に生産される電解銅粉，アトマイズ銅粉等を使用することが好ましい。
Cr粉末を焼結して得た多孔質体に溶浸させるCuは、工業的に製造されるタフピッチ銅，りん脱酸銅，無酸素銅等の金属Cu板、あるいは電解銅粉，アトマイズ銅粉等のCu粉末を使用するのが好ましい。なお、混合粉を用い、さらに十分な加圧を行ない、Cuを溶浸する必要がないものについては、実際には多孔質体ではない。すなわち本発明において、多孔質体とは溶浸技術の分野における通常の用法に従い、溶浸が可能な程度の気孔を有する物体を指す。好ましい気孔率としては、水銀圧下法（ＪＩＳ R1655：2003）で得られる値で15〜65体積％程度である。
The Cu powder is preferably an industrially produced electrolytic copper powder, atomized copper powder or the like.
Cu to be infiltrated into a porous body obtained by sintering Cr powder is an industrially manufactured metal Cu plate such as tough pitch copper, phosphorous deoxidized copper, oxygen-free copper, or electrolytic copper powder, atomized copper powder. It is preferable to use Cu powder such as. In addition, what does not need to infiltrate Cu by using mixed powder and performing sufficient pressurization is not actually a porous body. That is, in the present invention, the porous body refers to an object having pores that can be infiltrated in accordance with the usual usage in the field of infiltration technology. A preferable porosity is about 15 to 65% by volume obtained by a mercury reduction method (JIS R1655: 2003).
本発明では、偏平したCr相の平均アスペクト比が1.0超え100未満である。平均アスペクト比が1.0以下では、面内の方向の熱膨張率の低減効果が得られない。一方、100以上とするには圧延回数が多く、負担が大きくなる上、放熱用材料に要求される良好な薄板形状とすることが困難となる。
Cr相のアスペクト比は、Cr−Cu合金の厚み方向を含む断面のうち、偏平したCr相の長径が最大となる方向を含む断面、さらに具体的には溶浸体を冷間圧延した後の断面（圧延方向および圧下方向を含む断面）を光学顕微鏡で観察して求められ、下記の(2)式で算出される値である。そして、50〜100倍の光学顕微鏡で観察した任意の１視野の平均値を求める。なお、観察した視野に全体が入っているCr相について測定する。また複数のCr相が合体して形成されているように見えるものは、複数のCr相に分解し、分解した各Cr相のアスペクト比を求める。
In the present invention, the average aspect ratio of the flat Cr phase is more than 1.0 and less than 100. When the average aspect ratio is 1.0 or less, the effect of reducing the coefficient of thermal expansion in the in-plane direction cannot be obtained. On the other hand, when the number is 100 or more, the number of rolling is large, the burden is increased, and it is difficult to obtain a favorable thin plate shape required for the heat dissipation material.
The aspect ratio of the Cr phase is the cross section including the direction in which the major axis of the flat Cr phase is the largest among the cross sections including the thickness direction of the Cr-Cu alloy, more specifically, after cold rolling the infiltrant. It is a value calculated by observing the cross section (cross section including the rolling direction and the rolling direction) with an optical microscope and calculated by the following equation (2). And the average value of arbitrary 1 visual fields observed with the optical microscope 50-100 times is calculated | required. In addition, it measures about the Cr phase in which the whole is in the observed visual field. In addition, what appears to be formed by combining a plurality of Cr phases is decomposed into a plurality of Cr phases, and the aspect ratio of each decomposed Cr phase is obtained.
アスペクト比＝Ｌ1／Ｌ2 ・・・(2)
なお(2)式において、Ｌ1は、Cr−Cu合金の厚み方向を含む断面のうち、偏平したCr相の長径が最大となる方向を含む断面において長径が最大となる方向の最大長さを指し、Ｌ2は、Cr−Cu合金の厚み方向を含む断面のうち、偏平したCr相の長径が最大となる方向を含む断面において厚み方向の最大長さを指す。冷間圧延を施して得られるCr−Cu合金の場合には、上記の偏平したCr相の長径が最大となる方向は圧延方向である。また、２方向への圧延を行なう場合には、２方向のうち偏平したCr相の長径が最大となる圧延方向である。
Aspect ratio = L 1 / L 2 (2)
In the formula (2), L 1 is the maximum length in the direction in which the major axis is maximum in the cross section including the direction in which the major axis of the flat Cr phase is maximized among the sections including the thickness direction of the Cr—Cu alloy. L 2 indicates the maximum length in the thickness direction in the cross section including the direction in which the major axis of the flat Cr phase becomes the maximum among the cross sections including the thickness direction of the Cr—Cu alloy. In the case of a Cr—Cu alloy obtained by cold rolling, the direction in which the major axis of the flat Cr phase becomes the maximum is the rolling direction. In addition, when rolling in two directions, it is the rolling direction in which the major axis of the flat Cr phase in the two directions is maximized.
本発明では、溶浸体のまま、あるいは溶浸後に均質化時効熱処理を施した後、容易に冷間圧延が可能である。さらに必要に応じて軟質化時効熱処理を施す。これらの熱処理や冷間圧延によって、熱膨張率を低減することができる。ただし、その効果を得るためには、冷間圧延にて総圧下率（すなわち100×〔ｔ0 −ｔ〕／ｔ0 ；ｔ0 は初期の板厚，ｔは圧延後の板厚）が10％以上の圧下を付与することによって、1.0を超える平均アスペクト比を有するCr相を生成させることが必要である。 In the present invention, cold rolling can be easily performed with the infiltrated body or after performing homogenization aging heat treatment after infiltration. Further, softening and aging heat treatment is performed as necessary. The thermal expansion coefficient can be reduced by these heat treatments and cold rolling. However, in order to obtain the effect, the total rolling reduction (that is, 100 × [t 0 −t] / t 0 ; t 0 is the initial plate thickness, and t is the plate thickness after rolling) is 10 in cold rolling. It is necessary to produce a Cr phase having an average aspect ratio of greater than 1.0 by applying a reduction of at least%.
原料としてはアスペクト比が1.0〜2.0のCr粉末を使用することが好ましい。より好ましくは1.0〜1.5であり、さらに好ましくは1.0〜1.2である。ここでいうCr粉末のアスペクト比は、Cr粉末の個々のアスペクト比を平均した値であり、具体的にはたとえば紙面上にばらまいたCr粉末を上から観察し、個々の粒子の長径と短径の比を求めて算出した値であり、(2)式で定義されるアスペクト比とは異なる。 As a raw material, it is preferable to use Cr powder having an aspect ratio of 1.0 to 2.0. More preferably, it is 1.0-1.5, More preferably, it is 1.0-1.2. The aspect ratio of the Cr powder here is an average value of the individual aspect ratios of the Cr powder. Specifically, for example, the Cr powder dispersed on the paper surface is observed from above, and the major axis and minor axis of each particle are observed. This is a value calculated by calculating the ratio, and is different from the aspect ratio defined by equation (2).
発明者らが検討した結果、圧下率の増加（すなわち偏平Cr相のアスペクト比の増大）とともに、ハンダ付け接合の温度に比べて高温まで加熱した後も低い熱膨張率が安定して保たれるようになることが分かった。このため、特に800℃を超える高温まで加熱されるロウ付け接合を行なう場合には、圧下率を大きく設定することが好ましい。高温に加熱した後の熱膨張率の安定性という観点から圧下率は30％以上が好ましく、より好ましい範囲は50％以上である。圧下率から予測できるCr相のアスペクト比は、圧下率が10％のときは1.1程度，圧下率30％のときが1.4，圧下率50％のときが2.0，圧下率が90％のときが10程度，圧下率が99％のときが100程度となる。 As a result of investigations by the inventors, as the rolling reduction increases (that is, the aspect ratio of the flat Cr phase increases), a low thermal expansion coefficient is stably maintained even after heating to a higher temperature than the temperature of soldering. I found out that For this reason, it is preferable to set a large rolling reduction, especially when performing brazing joining heated to high temperature exceeding 800 degreeC. From the viewpoint of the stability of the coefficient of thermal expansion after heating to a high temperature, the rolling reduction is preferably 30% or more, and more preferably 50% or more. The aspect ratio of the Cr phase that can be predicted from the rolling reduction is about 1.1 when the rolling reduction is 10%, 1.4 when the rolling reduction is 30%, 2.0 when the rolling reduction is 50%, and 10 when the rolling reduction is 90%. About 100 when the rolling reduction is 99%.
ただし、圧延後の平均アスペクト比を実測すると、上記の値の通りにならないことも多く、しばしば予測値よりも大きい値となる。発明者らが多くの実験から実測される平均アスペクト比を求めたところ、圧下率80％の場合で20〜24であった。この値は、上記に従う予測値（＝5.0）より大きく、予測値の２乗（＝25）より小さかった。そのため実際には、たとえば圧下率30％のときに1.4の２乗程度、圧下率50％のときに2.0の２乗程度の平均アスペクト比を上限とする範囲でばらつきを持つと考えられる。 However, when the average aspect ratio after rolling is actually measured, the average value is often not as described above, and is often a value larger than the predicted value. When the inventors calculated the average aspect ratio actually measured from many experiments, it was 20 to 24 when the rolling reduction was 80%. This value was larger than the predicted value (= 5.0) according to the above and smaller than the square of the predicted value (= 25). Therefore, in practice, for example, it is considered that there is variation within a range in which the average aspect ratio is about 1.4 squared when the rolling reduction is 30% and the average aspect ratio is about 2.0 squared when the rolling reduction is 50%.
一方、99％を超える圧下を付与するためには、冷間圧延でのパス回数が顕著に増大し、冷間圧延に長時間を要するので、放熱用材料の生産効率が著しく低下する。したがって、99％以下の圧下を付与することが好ましい。ただし90％以上の圧下を付与すると溶浸体の端部に割れが生じ易くなり、歩留りの低下を招く。したがって、90％未満の圧下を付与することが一層好ましい。 On the other hand, in order to give a reduction exceeding 99%, the number of passes in the cold rolling is remarkably increased, and a long time is required for the cold rolling, so that the production efficiency of the heat radiation material is significantly reduced. Therefore, it is preferable to apply a reduction of 99% or less. However, if a reduction of 90% or more is applied, the end of the infiltrant tends to crack, leading to a decrease in yield. Therefore, it is more preferable to apply a reduction of less than 90%.
また、偏平したCr相の密度はCr−Cu合金の厚み方向の１mmあたり200個以下であることが好ましい。厚み方向に200個／mmを超えるCr相が存在すると、厚み方向の熱伝導率が著しく低下し、放熱部品としての十分な放熱性能が得られないという傾向があるからである。好ましくは100個／mm以下である。なお、合金の一様性の観点から10個／mm以上とすることが一層好ましい。
Further, the density of the flat Cr phase is preferably 200 or less per 1 mm in the thickness direction of the Cr—Cu alloy. This is because if there is a Cr phase exceeding 200 pieces / mm in the thickness direction, the thermal conductivity in the thickness direction is remarkably lowered, and sufficient heat dissipation performance as a heat dissipation component tends not to be obtained. Preferably it is 100 pieces / mm or less. Incidentally, the even more preferred child and 10 / mm or more from the viewpoint of the uniformity of the alloy.
なお本発明のCr−Cu溶浸体において、冷間圧延ができるほどに加工性が改善した理由は、現在までのところ明らかではないが、最適な焼結，溶浸条件を選択することによって溶浸体中のガス成分が低減したこと等が原因であると考えられる。
また発明者らは、溶浸体のＯ，Ｎ，Ｃの含有量を低減すれば、冷間での加工性が著しく向上するという知見を得た。すなわち、溶浸体中のＯ含有量を0.08質量％以下，Ｎ含有量を0.05質量％以下，Ｃ含有量を0.05質量％以下とすることによって、30％以上の圧下を加えたときのCr−Cu溶浸体の割れが大幅に減少することを見出した。さらに、溶浸体中のＯ含有量を0.03質量％以下，Ｎ含有量を0.02質量％以下，Ｃ含有量を0.01質量％以下とすることによって、60％以上の圧下を加えたときのCr−Cu溶浸体の割れを抑制できることを見出した。
The reason why the workability of the Cr-Cu infiltrate of the present invention has improved to such an extent that it can be cold-rolled is not clear so far. However, by selecting the optimum sintering and infiltration conditions, The cause is considered to be a reduction in gas components in the immersion body.
The inventors have also found that if the content of O, N, C in the infiltrated body is reduced, the workability in the cold is remarkably improved. That is, when the O content in the infiltrate is 0.08% by mass or less, the N content is 0.05% by mass or less, and the C content is 0.05% by mass or less, Cr- It has been found that the cracking of the Cu infiltrate is greatly reduced. Furthermore, when the O content in the infiltrate is 0.03% by mass or less, the N content is 0.02% by mass or less, and the C content is 0.01% by mass or less, Cr- It was found that cracking of the Cu infiltrate can be suppressed.
ここで、Ｏ，Ｎ，Ｃの含有量とCr−Cu溶浸体の割れとの関係について説明する。発明者らは、 Cr粉末を自然充填し、真空中あるいは水素雰囲気中で焼結して、気孔率45体積％（Cuを溶浸した後のCr含有量に換算すると50質量％に相当する）となる焼結体（70×70×10mm）を作製した。焼結温度は1200〜1500℃とした。得られた焼結体の上面にCu板を載置し、真空中で1200℃に加熱してCuを溶解し、焼結体に溶浸させて溶浸体を得た。 Here, the relationship between the content of O, N, and C and cracking of the Cr—Cu infiltrate will be described. The inventors naturally filled Cr powder, sintered in a vacuum or hydrogen atmosphere, and had a porosity of 45% by volume (corresponding to 50% by mass in terms of Cr content after Cu infiltration) A sintered body (70 × 70 × 10 mm) was prepared. The sintering temperature was 1200-1500 ° C. A Cu plate was placed on the upper surface of the obtained sintered body, heated to 1200 ° C. in vacuum to dissolve Cu, and infiltrated into the sintered body to obtain an infiltrated body.
また、Cr粉末とCu粉末を混合した後で加圧成形した成形体の上面にCu板を載置し、真空中で1200℃に加熱してCuを溶解し、焼結と溶浸を同時に行ない、溶浸体を得た。
これらの溶浸体に均質化時効熱処理（加熱温度600℃，保持時間１時間）を施した。次いでフライス盤を用いて、このCr−Cu合金の表面に残留するCuを除去して厚さ９mmのCr−Cu合金板とした。得られたCr−Cu合金板の冷間圧延を行なって、厚さ５mmあるいは2.5mmまで圧下した。圧下率は、それぞれ44％，72％に相当する。冷間圧延の後でCr−Cu合金板の表面を目視で観察して、割れの有無を調査した。その結果を表１に示す。
In addition, a Cu plate is placed on the upper surface of the compact that has been pressure-molded after mixing Cr powder and Cu powder, heated to 1200 ° C in vacuum to dissolve Cu, and sintering and infiltration are performed simultaneously The infiltrated body was obtained.
These infiltrates were subjected to homogenization aging heat treatment (heating temperature 600 ° C., holding time 1 hour). Next, using a milling machine, Cu remaining on the surface of the Cr—Cu alloy was removed to obtain a 9 mm thick Cr—Cu alloy plate. The obtained Cr—Cu alloy sheet was cold-rolled to reduce the thickness to 5 mm or 2.5 mm. The rolling reductions correspond to 44% and 72%, respectively. After the cold rolling, the surface of the Cr—Cu alloy plate was visually observed to check for cracks. The results are shown in Table 1.
さらに、Crの焼結体（すなわち多孔質体）にCuを溶浸させると、CrがCu中に0.1〜2.0質量％固溶する。そのCuマトリックスに固溶したCrを、均質化時効熱処理および／または軟質化時効熱処理によってCu中に長径100ｎｍ（ナノメートル）以下，アスペクト比10未満の粒子状Cr相を析出させることができる。この粒子状Cr相の析出が熱膨張率を低減させ、さらに冷間圧延を行なって粒子状Cr相に方向性を付与することによって、板の面内の方向の熱膨張率を一層低減することが可能となる。 Furthermore, when Cu is infiltrated into a Cr sintered body (that is, a porous body), Cr is dissolved in 0.1 to 2.0 mass% in Cu. The Cr dissolved in the Cu matrix can precipitate a particulate Cr phase having a major axis of 100 nm (nanometer) or less and an aspect ratio of less than 10 in Cu by homogenization aging heat treatment and / or softening aging heat treatment. This precipitation of the particulate Cr phase reduces the coefficient of thermal expansion and further reduces the coefficient of thermal expansion in the in-plane direction by cold rolling to impart directionality to the particulate Cr phase. Is possible.
なお、より低い熱膨張率が必要な場合など、Crの一部または全てをMoおよび／またはＷに置き換えることも可能である。
次に、本発明のCr−Cu合金の製造方法について説明する。
本発明のCr−Cu合金の製造方法は、
(a)Cr粉末を焼結して多孔質体とした後でCuを溶浸することによって、Cu中に多量のCrを均一に分布させた溶浸体を得る、あるいは、Cr粉末とCu粉末を混合して焼結し、これに必要に応じてCuを溶浸して溶浸体を得る、
(b)溶浸体を必要に応じて均質化時効熱処理し、さらに冷間圧延し、さらに必要に応じて軟質化時効熱処理することによって、溶浸体のままの状態に比べて熱膨張率を低減させる
という点に特徴がある。
It is also possible to replace some or all of Cr with Mo and / or W when a lower coefficient of thermal expansion is required.
Next, the manufacturing method of the Cr-Cu alloy of this invention is demonstrated.
The method for producing the Cr-Cu alloy of the present invention comprises:
(a) Sintering Cr powder to form a porous body and then infiltrating Cu to obtain an infiltrated body in which a large amount of Cr is uniformly distributed in Cu, or Cr powder and Cu powder Is mixed and sintered, and if necessary, Cu is infiltrated to obtain an infiltrated body,
(b) The infiltrated body is subjected to homogenization aging heat treatment as necessary, further cold-rolled, and further subjected to softening aging heat treatment as necessary, so that the coefficient of thermal expansion is increased as compared to the state of the infiltrated body. It is characterized in that it is reduced.
Cr−Cu合金を製造するにあたって、原料となるCr粉末を単独で、あるいはCu粉末と混合した後、型に充填して必要に応じて加圧成形し、その充填まま材または成形体を焼結して得られた焼結体に必要に応じてCuを溶浸させる。
加圧成形を行なう成形工程では、使用する原料の充填性や密度の目標値に応じて圧力を調整しながら成形する。Cr粉末を単独で使用する場合は、その後のCuの溶浸工程は不可欠である。Cr粉末とCu粉末を混合して使用する場合は、溶浸工程を省略してもかまわない。また焼結と溶浸を同時に行なうことも可能である。
When producing Cr-Cu alloy, Cr powder as a raw material is mixed alone or mixed with Cu powder, then filled into a mold and pressed as needed, and the material or compact is sintered as it is filled Cu is infiltrated into the sintered body obtained as necessary.
In the molding process in which pressure molding is performed, molding is performed while adjusting the pressure according to the target value of the filling property and density of the raw material to be used. When Cr powder is used alone, the subsequent Cu infiltration process is indispensable. When mixing and using Cr powder and Cu powder, the infiltration process may be omitted. It is also possible to perform sintering and infiltration at the same time.
焼結の条件は、1000〜1600℃の範囲内（望ましくは1050〜1450℃の範囲内）の温度で30〜300分保持することが好ましい。雰囲気は水素雰囲気または真空が好ましい。
溶浸は従来から知られている技術を使用する。たとえば多孔質体の上面および／または下面に純Cuの板や粉末を配置させ、1100〜1300℃の範囲内（望ましくは1150〜1250℃の範囲内）の温度で20〜120 分保持する。雰囲気は水素雰囲気または真空が好ましい。ただし、溶浸した後の加工性向上の観点から真空中で溶浸するのが好ましい。
The sintering condition is preferably maintained at a temperature in the range of 1000 to 1600 ° C. (desirably in the range of 1050 to 1450 ° C.) for 30 to 300 minutes. The atmosphere is preferably a hydrogen atmosphere or a vacuum.
For infiltration, a conventionally known technique is used. For example, a pure Cu plate or powder is placed on the upper surface and / or lower surface of the porous body, and held at a temperature in the range of 1100 to 1300 ° C. (preferably in the range of 1150 to 1250 ° C.) for 20 to 120 minutes. The atmosphere is preferably a hydrogen atmosphere or a vacuum. However, it is preferable to infiltrate in vacuum from the viewpoint of improving workability after infiltration.
なお本発明者らの研究によれば、CrとCuの混合粉を用い、焼結と同時に溶浸した後の冷却速度、あるいはCr粉末を焼結した多孔質体、またはCrとCuの混合粉を焼結した焼結体にCuを溶浸した後の冷却速度は、溶浸体の熱膨張率に影響を及ぼすことが判明した。具体的には、冷却速度が600℃／分以下であることが、より大きな熱膨張率の低減を達成できるので好ましい。現状では、冷却速度に応じて熱膨張率が変化する原因は明らかではないが、焼結中あるいは溶浸中にCuマトリックスに固溶したCrが熱処理によって析出する際に、冷却速度に応じて形態が変化するためと考えられる。 According to the study by the present inventors, a mixed powder of Cr and Cu, a cooling rate after infiltration simultaneously with sintering, a porous body obtained by sintering Cr powder, or a mixed powder of Cr and Cu It has been found that the cooling rate after infiltrating Cu into the sintered body obtained by sintering the material affects the thermal expansion coefficient of the infiltrated body. Specifically, it is preferable that the cooling rate is 600 ° C./min or less because a larger reduction in the coefficient of thermal expansion can be achieved. At present, the cause of the change in the coefficient of thermal expansion according to the cooling rate is not clear, but when Cr dissolved in the Cu matrix during sintering or infiltration precipitates by heat treatment, the form depends on the cooling rate. Is considered to change.
溶浸体に冷間圧延を行なう前に、必要に応じて均質化時効熱処理を施す。その温度は300〜1050℃の範囲内が好ましい。均質化時効熱処理の温度が300℃未満では、均質化や時効の効果が得られない。一方、1050℃を超えると、溶浸したCuが溶解して流れ出す惧れがある。保持時間は30分以上が好ましい。雰囲気は真空が好ましい。
溶浸した後、あるいはさらに均質化時効熱処理を施した後で、溶浸体の酸化層や表面に残留する純Cuを除去するために、Cr−Cu合金に機械加工（たとえばフライス盤による切削加工，砥石による研削加工等）を行なうことが好ましい。その後、冷間圧延を行なう。冷間で圧下を付与することによって、熱膨張率を低減できる。特に10〜90％という圧下率が比較的小さい通常の圧下であっても熱膨張率を低減できる。
Before performing cold rolling on the infiltrated body, homogenized aging heat treatment is performed as necessary. The temperature is preferably in the range of 300-1050 ° C. If the temperature of the homogenizing aging heat treatment is less than 300 ° C., the homogenizing and aging effects cannot be obtained. On the other hand, if it exceeds 1050 ° C., the infiltrated Cu may be dissolved and flow out. The holding time is preferably 30 minutes or longer. The atmosphere is preferably a vacuum.
After infiltration, or after further homogenization aging heat treatment, in order to remove the pure Cu remaining on the oxide layer and the surface of the infiltrant, machining to Cr-Cu alloy (for example, cutting with a milling machine, It is preferable to perform grinding with a grindstone. Thereafter, cold rolling is performed. By applying the cold reduction, the coefficient of thermal expansion can be reduced. In particular, the coefficient of thermal expansion can be reduced even at a normal reduction of 10 to 90%.
冷間圧延を行なった後、必要に応じて軟質化時効熱処理を施す。その温度は300〜900℃の範囲内が好ましい。300℃未満では、軟質化の効果が得られない。一方、900℃を超えると、溶浸したCuが溶解して流れ出す惧れがある。保持時間は30分以上が好ましい。雰囲気は真空が好ましい。
溶浸体に冷間圧延を行なうことに加え、さらに均質化時効熱処理，軟質化時効熱処理を組み合わせることによって熱膨張率が低減する原因は、現状では明らかではないが、焼結工程あるいは溶浸工程においてCuマトリックスに固溶したCrが熱処理によって析出し、圧延によってその析出物が有利な方向に配向するためと考えられる。この効果を得るためには上記の通り10％以上の圧下を付与することが必要である。
After cold rolling, softening and aging heat treatment is performed as necessary. The temperature is preferably in the range of 300 to 900 ° C. If it is less than 300 ° C., the effect of softening cannot be obtained. On the other hand, when the temperature exceeds 900 ° C., the infiltrated Cu may be dissolved and flow out. The holding time is preferably 30 minutes or longer. The atmosphere is preferably a vacuum.
The reason why the coefficient of thermal expansion is reduced by combining cold rolling to the infiltrated material, and further combining the homogenizing aging heat treatment and softening aging heat treatment is not clear at present, but the sintering process or the infiltration process. This is because Cr dissolved in the Cu matrix is precipitated by heat treatment, and the precipitate is oriented in an advantageous direction by rolling. In order to obtain this effect, it is necessary to apply a reduction of 10% or more as described above.
なお、たとえば高い強度や剛性が必要な部材として用いる場合には、冷間圧延後の軟質化時効熱処理を省略することも可能である。また、たとえば高温のロウ付け接合により組立てを行なう場合では、接合時の加熱により、冷間圧延後の熱処理と同様の効果を得ることができる。
なお、冷間圧延の代わりに、スウェージング加工，ダイス引き抜き，鍛造等の冷間加工を行なっても良い。
For example, when used as a member that requires high strength and rigidity, the softening aging heat treatment after cold rolling can be omitted. For example, in the case of assembling by high-temperature brazing joining, the same effect as that of the heat treatment after cold rolling can be obtained by heating at the time of joining.
Instead of cold rolling, cold working such as swaging, die drawing, and forging may be performed.
また冷間圧延材の面内異方性を減ずるためには、垂直な２方向への圧延（いわゆるクロス圧延）を行なうことも有効であると考えられる。
本発明によるCr−Cu放熱板は、冷延ままの状態、あるいはさらに軟質化時効熱処理を施した状態で使用することができる。また必要に応じて半導体の台座としての使用を想定した耐食性および電食に対する性能を向上させる目的で、表面にさらにNiめっき，Auめっき，Agめっき等を単独で、あるいは組み合わせて施すこともできる。各種のめっきを施すことで、各種のはんだ接合やロウ付け接合の適用が可能になる。粉末冶金法に圧延法を組み合わせた本発明材では、低い熱膨張率が800℃を超える高温に曝された後も保持されるので、接合温度が750℃以上と高くなるロウ付け接合を行なう用途に対し、本発明材は非常に有利に適用できる。
In order to reduce the in-plane anisotropy of the cold rolled material, it is considered effective to perform rolling in two perpendicular directions (so-called cross rolling).
The Cr—Cu heat sink according to the present invention can be used in a cold-rolled state or a state in which softening and aging heat treatment is applied. If necessary, Ni plating, Au plating, Ag plating, or the like can be further applied to the surface alone or in combination for the purpose of improving the corrosion resistance and performance against electric corrosion assuming use as a semiconductor pedestal. By applying various types of plating, various solder joints and brazing joints can be applied. In the present invention material, which combines the powder metallurgy method with the rolling method, the low thermal expansion coefficient is maintained even after being exposed to a high temperature exceeding 800 ° C., so that the bonding temperature is increased to 750 ° C. or higher. On the other hand, the material of the present invention can be applied very advantageously.
＜実施例１＞
Cr粉末（粒度：50〜200μｍ，Ｏ：0.04〜0.15質量％，Ｎ：0.01〜0.08質量％，Ｃ：0.01〜0.08質量％）を自然充填あるいは加圧成形し、真空中あるいは水素雰囲気中で焼結して、気孔率25〜55体積％（Cuを溶浸した後のCr含有量に換算すると70〜40質量％に相当する）となる焼結体（70mm×70mm×10mm）を作製した。焼結温度は1200〜1500℃、焼結時間は90分とした。得られた焼結体の上面にCu板を載置し、真空中で1200℃に加熱（保持時間：1.5時間）してCuを溶解し、焼結体に溶浸させて溶浸体（Ｏ：0.01〜0.07質量％，Ｎ：0.004〜0.04質量％，Ｃ：0.004〜0.04質量％）を得た。溶浸した後の平均冷却速度は1200〜200℃の温度領域にて200〜600℃／時間とした。
<Example 1>
Cr powder (particle size: 50 to 200 μm, O: 0.04 to 0.15 mass%, N: 0.01 to 0.08 mass%, C: 0.01 to 0.08 mass%) is naturally filled or pressure-molded and baked in vacuum or in a hydrogen atmosphere As a result, a sintered body (70 mm × 70 mm × 10 mm) having a porosity of 25 to 55% by volume (corresponding to 70 to 40% by mass in terms of Cr content after Cu was infiltrated) was produced. The sintering temperature was 1200-1500 ° C., and the sintering time was 90 minutes. A Cu plate is placed on the upper surface of the obtained sintered body, heated to 1200 ° C. in a vacuum (holding time: 1.5 hours) to dissolve Cu, and infiltrated into the sintered body to infiltrate (O : 0.01 to 0.07 mass%, N: 0.004 to 0.04 mass%, C: 0.004 to 0.04 mass%). The average cooling rate after infiltration was set to 200 to 600 ° C./hour in the temperature range of 1200 to 200 ° C.
また、Cr粉末（粒度：50〜200μｍ）とCu粉末を混合した後で加圧成形した成形体の上面にCu板を載置し、真空中で1200℃に加熱（保持時間：１時間）してCuを溶解し、焼結と溶浸を同時に行ない、溶浸体（Ｏ：0.01〜0.08質量％，Ｎ：0.004〜0.05質量％，Ｃ：0.004〜0.05質量％）を得た。
これらの溶浸体の一部には均質化時効熱処理（加熱温度：500〜650℃，保持時間：１時間，雰囲気：真空）を施した。
In addition, a Cu plate is placed on the upper surface of a compact that has been pressure-molded after mixing Cr powder (particle size: 50-200 μm) and Cu powder, and heated to 1200 ° C. in a vacuum (holding time: 1 hour). Cu was melted and sintered and infiltrated at the same time to obtain an infiltrated body (O: 0.01 to 0.08 mass%, N: 0.004 to 0.05 mass%, C: 0.004 to 0.05 mass%).
A part of these infiltrates was subjected to homogenization aging heat treatment (heating temperature: 500 to 650 ° C., holding time: 1 hour, atmosphere: vacuum).
次いでフライス盤を用いて、このCr−Cu合金の表面に残留するCuを除去して厚さ９mmのCr−Cu合金板とした。このCr−Cu合金板の冷間圧延を行なって、厚さ2.5mmまで圧下（圧下率：72％）した。圧下率から見積もられるCr相のアスペクト比は約3.6〜13の範囲である。
これらのCr−Cu合金板に、熱膨張率を調整するための軟質化時効熱処理（加熱温度：450〜800℃，保持時間：１時間，雰囲気：真空）を施した。
Next, using a milling machine, Cu remaining on the surface of the Cr—Cu alloy was removed to obtain a 9 mm thick Cr—Cu alloy plate. The Cr-Cu alloy sheet was cold-rolled and reduced to a thickness of 2.5 mm (reduction rate: 72%). The aspect ratio of the Cr phase estimated from the rolling reduction is in the range of about 3.6-13.
These Cr—Cu alloy sheets were subjected to softening aging heat treatment (heating temperature: 450 to 800 ° C., holding time: 1 hour, atmosphere: vacuum) for adjusting the coefficient of thermal expansion.
さらに、室温〜200℃の範囲の平均熱膨張率（圧延方向）を測定した。その結果を表２に示す。 Furthermore, the average coefficient of thermal expansion (rolling direction) in the range of room temperature to 200 ° C. was measured. The results are shown in Table 2.
なおＡ〜Ｑの発明例およびＴ，Ｕについてレーザーフラッシュ法にて熱伝導率を測定した。レーザーフラッシュ法を採用するにあたって、Ａ〜ＱおよびＴ，Ｕと同一成分のCr−Cu合金板を作製した。そのCr−Cu合金板の圧延前の厚さを変更することにより、Ａ〜Ｑの発明例と同じ圧下率の冷間圧延を行なうことによって２mm厚または0.8mm厚になるように調整した。Ｔ，Ｕは冷間圧延せず、最終板厚まで切削加工および研削加工によって減厚した。このようにしてＡ〜Ｑ，Ｔ，Ｕと同一履歴となるようにして得られた２mm厚のCr−Cu合金板から試験片を採取して、その厚さ方向の熱伝導率をレーザーフラッシュ法で測定し、0.8mm厚のCr−Cu合金板から試験片を採取して、その面内の方向の熱伝導率をレーザーフラッシュによる２次元法で測定した。その結果、Ａ〜Ｑの厚み方向の熱伝導率は約150Ｗ／ｍ・Ｋ，面内の方向の熱伝導率は約200Ｗ／ｍ・Ｋであり、いずれの方向も良好な熱伝導率を有することを確認した。 In addition, thermal conductivity was measured by the laser flash method for Invention Examples A to Q and T and U. In adopting the laser flash method, Cr—Cu alloy plates having the same components as A to Q and T and U were prepared. By changing the thickness of the Cr—Cu alloy plate before rolling, cold rolling was performed at the same reduction ratio as that of the inventive examples A to Q, so that the thickness was adjusted to 2 mm or 0.8 mm. T and U were not cold-rolled but were reduced to the final thickness by cutting and grinding. A test piece was taken from the 2 mm thick Cr-Cu alloy plate obtained so as to have the same history as A to Q, T, U in this way, and the thermal conductivity in the thickness direction was measured by the laser flash method. A test piece was taken from a 0.8 mm thick Cr—Cu alloy plate, and the thermal conductivity in the in-plane direction was measured by a two-dimensional method using a laser flash. As a result, the thermal conductivity in the thickness direction of A to Q is about 150 W / m · K, the thermal conductivity in the in-plane direction is about 200 W / m · K, and both directions have good thermal conductivity. It was confirmed.
Ｔでは面内方向，厚み方向ともに熱伝導率は180Ｗ／ｍ・Ｋであった。熱処理を施していないＵでは、面内方向，厚み方向とも熱伝導率は140Ｗ／ｍ・Ｋであった。
なお、走査型電子顕微鏡（いわゆるＳＥＭ）を用いて調査を行ない、Ａ〜ＷのうちのＵを除く全合金では、長径が100ｎｍ以下で、アスペクト比が10未満の粒子状Cr相がCu相中に25〜100個／μｍ2 の割合で析出していることを確認した。
In T, the thermal conductivity was 180 W / m · K in both the in-plane direction and the thickness direction. In U which was not heat-treated, the thermal conductivity was 140 W / m · K in both the in-plane direction and the thickness direction.
In addition, the investigation was conducted using a scanning electron microscope (so-called SEM). In all alloys except U among A to W, the particulate Cr phase having a major axis of 100 nm or less and an aspect ratio of less than 10 is in the Cu phase. It was confirmed that the particles were deposited at a rate of 25 to 100 / μm 2 .
これらとは別に、半導体用放熱体として、半導体素子にハンダ付けして、接合の状況を調査した。発明例Ｏの溶浸体を５mm厚まで減厚加工した後、冷間圧延を行ない作製したCr−Cu合金板（厚さ0.8mm）を10mm×５mm×0.8mmの大きさにプレス加工し、さらに３μｍの厚さに電解ニッケルめっきを施した後、Auめっき２μｍを施した。また、メタライズし、Ni＋Auめっき処理した面を有する５mm×３mm×１mmの大きさのアルミナ板を準備し、Cr−Cu合金板とアルミナ板をハンダ付け（使用したハンダ：Sn−３質量％Ag−0.5質量％Cu）した。その結果、接合部分に問題は認められなかった。 Apart from these, as a semiconductor heat sink, soldering was performed on a semiconductor element, and the bonding situation was investigated. After reducing the thickness of the infiltrated body of Invention Example O to 5 mm, cold-rolling the produced Cr-Cu alloy plate (thickness 0.8 mm) to a size of 10 mm x 5 mm x 0.8 mm, Furthermore, after electrolytic nickel plating was applied to a thickness of 3 μm, Au plating was applied with 2 μm. Also, a 5 mm × 3 mm × 1 mm alumina plate having a metallized and Ni + Au plated surface was prepared, and a Cr—Cu alloy plate and an alumina plate were soldered (solder used: Sn-3 mass% Ag— 0.5 mass% Cu). As a result, no problem was found in the joined portion.
これによって各種業務無線機，アマチュア無線機をはじめ、GSM/AMP方式自動車電話，広帯域無線インターネット接続モジュール等に用いられるシリコン半導体、GaAs半導体による高周波デバイス用台座，ベース，プレート用あるいは高輝度LED用台座に用いることが可能であることが確かめられた。
次に、発明例ＥのCr−Cu合金板（厚さ2.5mm ）を50mm×100mm×2.5mm の大きさに加工し、厚さ５μｍのNiめっきを施した。このCr−Cu合金板にＤＢＡ基板と半導体素子を、到達温度が 245℃となるリフロー処理によってハンダ付け（使用したハンダ：Sn−３質量％Ag−0.5質量％Cu）した。
As a result, silicon radios used for various business radios, amateur radios, GSM / AMP type automobile telephones, broadband wireless Internet connection modules, GaAs semiconductors, high frequency device bases, bases, plates or high brightness LED bases It was confirmed that it was possible to use it.
Next, the Cr—Cu alloy plate (thickness 2.5 mm) of Invention Example E was processed to a size of 50 mm × 100 mm × 2.5 mm and Ni plating with a thickness of 5 μm was applied. The DBA substrate and the semiconductor element were soldered to this Cr—Cu alloy plate by a reflow process at which the ultimate temperature was 245 ° C. (solder used: Sn-3 mass% Ag-0.5 mass% Cu).
この電子部品冷却体の熱衝撃試験（加熱温度：−40℃，120℃，保持時間：５分）を行なった。熱衝撃試験は WINTEC LT20型液槽式熱衝撃試験器（楠本化成製）を使用した。試験が終了した後、超音波探傷によってクラックの有無を調査した。
発明例の電子部品冷却体は、3000サイクル終了後、接合界面における剥離やクラックは認められなかった。
The electronic component cooling body was subjected to a thermal shock test (heating temperature: −40 ° C., 120 ° C., holding time: 5 minutes). For the thermal shock test, a WINTEC LT20 liquid tank thermal shock tester (manufactured by Enomoto Kasei) was used. After the test was completed, the presence or absence of cracks was investigated by ultrasonic flaw detection.
In the electronic component cooling body of the inventive example, peeling and cracking at the joint interface were not observed after 3000 cycles.
これによってインバーター等のパワーデバイス半導体の放熱板として使用できることが確かめられた。
＜実施例２＞
実施例１と同じCr粉末を自然充填し、真空中で焼結し、気孔率50体積％（Cuを溶浸した後のCr含有量に換算すると45質量％に相当する）となる焼結体（70×70×10mm）を作製した。焼結温度は1200〜1500℃とした。得られた焼結体の上面にCu板を載置し、真空中で1200℃に加熱してCuを溶解し、焼結体に溶浸させて溶浸体を得た。溶浸後の1200〜200℃の温度領域における平均冷却速度は200〜600℃／時間とした。この溶浸体をNo.１〜５の５個に分け、その一部に均質化時効熱処理（加熱温度600℃，保持時間１時間，雰囲気真空）を施した。
This confirmed that it can be used as a heat sink for power device semiconductors such as inverters.
<Example 2>
Sintered body in which the same Cr powder as in Example 1 is naturally filled and sintered in a vacuum to have a porosity of 50% by volume (corresponding to 45% by mass when converted to the Cr content after Cu is infiltrated). (70 × 70 × 10 mm) was produced. The sintering temperature was 1200-1500 ° C. A Cu plate was placed on the upper surface of the obtained sintered body, heated to 1200 ° C. in vacuum to dissolve Cu, and infiltrated into the sintered body to obtain an infiltrated body. The average cooling rate in the temperature range of 1200 to 200 ° C. after infiltration was set to 200 to 600 ° C./hour. This infiltrated body was divided into five pieces No. 1 to 5, and a part thereof was subjected to homogenization aging heat treatment (heating temperature 600 ° C., holding time 1 hour, atmosphere vacuum).
次いでフライス盤を用いて、このCr−Cu合金の表面に残留するCuを除去して厚さ1.6〜６mmのCr−Cu合金板とした。一部にはさらに冷間圧延を行なって、厚さ1.6mmまで圧下した。その後、実施例１と同様に室温〜200℃の範囲で平均熱膨張率（圧延方向）を測定した。各サンプルの処理条件を表３に示す。 Next, using a milling machine, Cu remaining on the surface of the Cr—Cu alloy was removed to obtain a Cr—Cu alloy plate having a thickness of 1.6 to 6 mm. Some were further cold rolled to reduce the thickness to 1.6 mm. Thereafter, the average thermal expansion coefficient (rolling direction) was measured in the range of room temperature to 200 ° C. as in Example 1. Table 3 shows the processing conditions for each sample.
なお、冷間圧延の後で圧延方向（No.５は合金板長手方向）の断面のサンプルを採取し、光学顕微鏡で観察するとともに、偏平したCr相のアスペクト比および厚み方向の個数を調査した。光学顕微鏡による観察面の一例を図１に示す（No.１：厚み方向１／２部，エッチング処理なし）。Cu相１中に偏平したCr相２が存在すること分かる。粒子状Cr相は光学顕微鏡では判別できない。図１中の黒点は、残留した研磨材である。
After cold rolling, a sample of a cross section in the rolling direction (No. 5 is the longitudinal direction of the alloy plate) was taken and observed with an optical microscope, and the aspect ratio of the flat Cr phase and the number in the thickness direction were investigated. . An example of an observation surface by an optical microscope is shown in FIG. 1 (No. 1: 1/2 part in the thickness direction, no etching treatment). It can be seen that a
実測されたアスペクト比は、No.１およびNo.２が約10，No.３およびNo.４が約3.5，No.５が約1.0であった。圧下率50％および73％で予想されるアスペクト比は2.0〜4.0および3.7〜13.7であるから、実測のアスペクト比は見積りの範囲内であった。偏平したCr相の厚み方向の個数は、No.１およびNo.２が約30個／mm，No.３およびNo.４が約20個／mmであった。 The actually measured aspect ratios of No. 1 and No. 2 were about 10, No. 3 and No. 4 were about 3.5, and No. 5 was about 1.0. Since the expected aspect ratios at the reduction ratios of 50% and 73% were 2.0 to 4.0 and 3.7 to 13.7, the measured aspect ratios were within the estimated range. The number of flattened Cr phases in the thickness direction was about 30 / mm for No. 1 and No. 2, and about 20 / mm for No. 3 and No. 4.
次に、走査型電子顕微鏡を用いた上記の調査法によって、No.１およびNo.３のみに、長径が100ｎｍ以下でアスペクト比が10未満（平均で約５）の粒子状の微細Cr相が、Cu相中に約30〜50個／μｍ2 の割合で析出していることを確認した。
以上の実施例１，２で説明した通り、本発明のCr−Cu合金は、低熱膨張率と高熱伝導率を併せ持ち、半導体用放熱板や半導体用放熱部品に好適な材料である。
Next, according to the above-described investigation method using a scanning electron microscope, only fine particles No. 1 and No. 3 have a particulate fine Cr phase having a major axis of 100 nm or less and an aspect ratio of less than 10 (average of about 5). It was confirmed that it was precipitated in the Cu phase at a rate of about 30 to 50 / μm 2 .
As described in Examples 1 and 2 above, the Cr—Cu alloy of the present invention has both a low thermal expansion coefficient and a high thermal conductivity, and is a suitable material for semiconductor heat sinks and semiconductor heat sink components.
１ Cu相
２ Cr相
1
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