JP5774377B2 - Method for manufacturing aluminum nitride-metal bonded substrate - Google Patents
Method for manufacturing aluminum nitride-metal bonded substrate Download PDFInfo
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- JP5774377B2 JP5774377B2 JP2011118421A JP2011118421A JP5774377B2 JP 5774377 B2 JP5774377 B2 JP 5774377B2 JP 2011118421 A JP2011118421 A JP 2011118421A JP 2011118421 A JP2011118421 A JP 2011118421A JP 5774377 B2 JP5774377 B2 JP 5774377B2
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- 229910052751 metal Inorganic materials 0.000 title claims description 81
- 239000002184 metal Substances 0.000 title claims description 81
- 238000000034 method Methods 0.000 title claims description 34
- 229910052782 aluminium Inorganic materials 0.000 title claims description 21
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims description 20
- 238000004519 manufacturing process Methods 0.000 title claims description 17
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 139
- 239000006061 abrasive grain Substances 0.000 claims description 40
- 239000000463 material Substances 0.000 claims description 29
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- 239000002245 particle Substances 0.000 claims description 8
- 150000004767 nitrides Chemical class 0.000 claims description 4
- 239000010954 inorganic particle Substances 0.000 claims 1
- 238000002844 melting Methods 0.000 claims 1
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- 239000010949 copper Substances 0.000 description 22
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- 239000000843 powder Substances 0.000 description 8
- 239000010410 layer Substances 0.000 description 7
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- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 5
- 239000011230 binding agent Substances 0.000 description 4
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- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
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- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 2
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- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 2
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- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
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- ZXGIFJXRQHZCGJ-UHFFFAOYSA-N erbium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Er+3].[Er+3] ZXGIFJXRQHZCGJ-UHFFFAOYSA-N 0.000 description 1
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- UZLYXNNZYFBAQO-UHFFFAOYSA-N oxygen(2-);ytterbium(3+) Chemical compound [O-2].[O-2].[O-2].[Yb+3].[Yb+3] UZLYXNNZYFBAQO-UHFFFAOYSA-N 0.000 description 1
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Description
本発明は、各種電子素子の実装基板や回路基板などとして用いられる窒化アルミニウム−金属接合基板の新規な製造方法に関する。 The present invention relates to a novel manufacturing method of an aluminum nitride-metal bonded substrate used as a mounting substrate or a circuit substrate for various electronic elements.
従来から、半導体素子を始めとする各種電子素子を搭載するための基板として、優れた絶縁性、放熱性、機械的特性などを有するセラミックス基板が使用されている。特に、発熱量が大きいパワートランジスタのような高出力型半導体素子やレーザ素子を搭載する基板には、高熱伝導率を有する窒化アルミニウム焼結体基板が多用されている。このような窒化アルミニウム焼結体基板を実装基板や回路基板として使用する場合、その表面に素子搭載部や回路部などを構成する金属層を形成することが不可欠である。また、上記金属層の形成方法として、窒化アルミニウム焼結体基板と金属基板とを、ロウ材を介して接合して接合体を構成する方法が行われている。 Conventionally, ceramic substrates having excellent insulating properties, heat dissipation properties, mechanical properties, and the like have been used as substrates for mounting various electronic devices including semiconductor devices. In particular, an aluminum nitride sintered substrate having a high thermal conductivity is frequently used for a substrate on which a high-power semiconductor element such as a power transistor having a large calorific value or a laser element is mounted. When such an aluminum nitride sintered body substrate is used as a mounting substrate or a circuit substrate, it is indispensable to form a metal layer constituting an element mounting portion or a circuit portion on the surface thereof. In addition, as a method for forming the metal layer, a method in which an aluminum nitride sintered body substrate and a metal substrate are joined via a brazing material to form a joined body is performed.
ところで、該窒化アルミニウム焼結体基板の製造工程においては、通常、焼結を複数枚の成形体を積み重ねて行うため、基板同士の接着を防止するために離型材（ＢＮ粉など）が使用され、これが焼成後に窒化アルミニウム焼結体基板表面に残留する。前記窒化アルミニウム焼結体基板と金属基板との接合において、上記離型材の残存は、窒化アルミニウム焼結体基板と金属基板との接合強度を低下させる等の問題を誘発する。そのため、焼成後の窒化アルミニウム焼結体基板より離型材などの付着物（異物）を除去する程度の清浄化加工、例えば、ホーニング処理のような衝撃力が弱い表面加工を施した後、金属基板との接合を行う方法が提案されている（特許文献１参照）。
上記ホーニング処理は、研磨加工に比べて大量生産性に優れ、衝撃力が少ないため、研磨加工を実施した場合には基板表面に砥石の研削痕が残って特定方向の基板強度が低下するおそれがあるのに対して、基板強度の低下などを招くおそれもなく、金属基板を接合する際の前処理として多用されている。
By the way, in the manufacturing process of the aluminum nitride sintered body substrate, usually, the sintering is performed by stacking a plurality of formed bodies, and therefore a release material (BN powder or the like) is used to prevent the substrates from being bonded to each other. This remains on the aluminum nitride sintered substrate surface after firing. In the joining of the aluminum nitride sintered body substrate and the metal substrate, the remaining release material induces problems such as lowering the joining strength between the aluminum nitride sintered body substrate and the metal substrate. For this reason, after performing a cleaning process that removes deposits (foreign matter) such as a release material from the sintered aluminum nitride substrate after firing, for example, a surface process with low impact force such as a honing process is performed, and then the metal substrate Has been proposed (see Patent Document 1).
The above honing process is superior in mass productivity and less impact force than polishing, so if polishing is performed, grinding marks of the grindstone may remain on the substrate surface and the substrate strength in a specific direction may decrease. On the other hand, it is frequently used as a pretreatment when bonding metal substrates without causing a decrease in substrate strength.
かかる窒化アルミニウム焼結体基板のホーニング処理には、前記特許文献１に記載されているように、各種の砥粒が使用されるが、ホーニング処理の処理条件によっては基板表面に与えるダメージが大きくなり、窒化アルミニウム焼結体基板の強度や窒化アルミニウム焼結体基板と銅板のような金属基板との接合体（接合基板）の熱サイクル特性などが低下するという問題がある。 Various types of abrasive grains are used for the honing treatment of the aluminum nitride sintered substrate, as described in Patent Document 1, but depending on the processing conditions of the honing treatment, damage to the substrate surface increases. There is a problem that the strength of the aluminum nitride sintered body substrate, the thermal cycle characteristics of the joined body (joined substrate) of the aluminum nitride sintered body substrate and a metal substrate such as a copper plate, and the like are degraded.
上記問題に対して、窒化アルミニウム焼結体基板よりも硬度の低い砥粒を用い、また、砥粒を被処理物に衝突させる際の衝撃力を、前記離型材を除去する程度の最小限に抑えることによって、基板表面に与えるダメージを小さくすることが提案されている（特許文献２参照）。
For the above problem, abrasive grains having a hardness lower than that of the aluminum nitride sintered body substrate are used, and the impact force when the abrasive grains collide with the workpiece is minimized to the extent that the release material is removed. It has been proposed to reduce the damage given to the substrate surface by suppressing (see Patent Document 2).
一方、上記金属基板との接合体を構成する場合、窒化アルミニウム焼結体基板はその機械的特性、特に曲げ強度や破壊靱性値が十分ではなく、更なる向上が求められている。即ち、曲げ強度あるいは破壊靭性値が小さいと、窒化アルミニウム焼結体基板に接合された金属基板によって形成された金属回路層に半導体素子を実装する際の応力や熱などにより窒化アルミニウム焼結体基板が破損したり、半導体素子の作動に伴う熱サイクルの繰り返しによって、前記金属回路層の接合部付近の窒化アルミニウム焼結体基板にクラックが発生し易くなったりし、耐熱サイクル特性及び信頼性が低下するという問題が生じる。 On the other hand, when constituting a bonded body with the metal substrate, the aluminum nitride sintered body substrate is not sufficient in mechanical properties, particularly bending strength and fracture toughness value, and further improvement is required. That is, when the bending strength or fracture toughness value is small, the aluminum nitride sintered substrate is caused by stress or heat when the semiconductor element is mounted on the metal circuit layer formed by the metal substrate bonded to the aluminum nitride sintered substrate. May be damaged or cracks may easily occur in the sintered aluminum nitride substrate near the joint of the metal circuit layer due to repeated thermal cycles associated with the operation of the semiconductor element, resulting in reduced heat cycle characteristics and reliability. Problem arises.
特に、最近のパワーモジュール用セラミックス基板においては、従来以上に厳しい熱サイクル下における使用が多くなってきており、耐熱衝撃性ひいては曲げ強度や破壊靱性値の向上が一層強く求められる状況である。 In particular, recent ceramic substrates for power modules are increasingly used under severer heat cycles than before, and there is a strong demand for improvement in thermal shock resistance, as well as bending strength and fracture toughness.
ところが、前記特許文献１、２に示される従来のホーニング処理の技術によれば、窒化アルミニウム焼結体基板と金属基板との接合強度は強固になるものの、かかるホーニング処理により、得られる接合基板全体の強度や熱サイクル特性などの改善においては、更なる改善の余地があった。 However, according to the conventional honing treatment techniques disclosed in Patent Documents 1 and 2, the bonding strength between the aluminum nitride sintered body substrate and the metal substrate is strengthened, but the entire bonding substrate obtained by the honing treatment is obtained. There was room for further improvement in the improvement of the strength and thermal cycle characteristics.
従って、本発明は、窒化アルミニウム焼結体基板と金属基板との接合強度の向上効果を発揮するのみでなく、更に、高強度で熱サイクル特性に優れた窒化アルミニウム−金属接合基板を安定にかつ再現性よく得ることのできる窒化アルミニウム−金属接合基板の製造方法を提供することにある。 Therefore, the present invention not only exhibits the effect of improving the bonding strength between the aluminum nitride sintered body substrate and the metal substrate, but also stably provides an aluminum nitride-metal bonded substrate having high strength and excellent thermal cycle characteristics. An object of the present invention is to provide a method of manufacturing an aluminum nitride-metal bonded substrate that can be obtained with good reproducibility.
本発明者らは、上記目的を達成すべく研究を重ねた結果、従来は窒化アルミニウム焼結体基板自体の強度低下に繋がると考えられていた処理条件、即ち窒化アルミニウム焼結体基板よりも硬度の高い砥粒を用い、且つ、該砥粒を液体中に特定量存在せしめ、これを特定の圧力で、窒化アルミニウム焼結体基板の被処理面に衝突させることにより、基板表面に付着していた離型材などを確実に除去しつつ、該被処理面の表面に何らかの変化を生じせしめ、金属基板接合後の窒化アルミニウム−金属接合基板において、抗折強度や熱サイクル特性を著しく向上せしめることができることを見出し、本発明を提案するに至った。 As a result of repeated researches to achieve the above object, the present inventors have conducted processing conditions that were conventionally considered to lead to a decrease in strength of the aluminum nitride sintered body substrate itself, that is, a hardness higher than that of the aluminum nitride sintered body substrate. High-abrasive grains are used, and a certain amount of the abrasive grains are present in the liquid, and this is caused to collide with the surface to be treated of the aluminum nitride sintered substrate with a specific pressure, thereby adhering to the substrate surface. It is possible to cause some change in the surface of the surface to be processed while reliably removing the mold release material, etc., and to significantly improve the bending strength and thermal cycle characteristics in the aluminum nitride-metal bonded substrate after bonding the metal substrate. The present inventors have found that this is possible and have come to propose the present invention.
即ち、本発明は、窒化アルミニウム焼結体基板の被処理面に砥粒を衝突せしめて改質した後、上記窒化アルミニウム焼結体の被処理面に金属基板を接合するに際し、前記砥粒として、窒化アルミニウム焼結体より高い硬度を有する砥粒を使用し、該砥粒を１０〜３０体積％の濃度で含有する液体（以下、砥粒を含有する液体を「砥粒スラリー」ともいう。）を、前記窒化アルミニウム焼結体基板の被処理面に対して、該被処理面にかかる圧力が０．００７〜０．０１２ＭＰａとなるように噴射することを特徴とする窒化アルミニウム−金属接合基板の製造方法である。 That is, according to the present invention, the abrasive grains collide with the surface to be processed of the aluminum nitride sintered body substrate for modification, and then when the metal substrate is joined to the surface to be processed of the aluminum nitride sintered body, A liquid having higher hardness than the aluminum nitride sintered body and containing the abrasive grains at a concentration of 10 to 30% by volume (hereinafter, the liquid containing the abrasive grains is also referred to as “abrasive slurry”). ) With respect to the surface to be processed of the aluminum nitride sintered substrate, the pressure applied to the surface to be processed is 0. 0 07-0. It is a manufacturing method of an aluminum nitride-metal bonded substrate characterized by spraying so as to be 0 12 MPa.
本発明の窒化アルミニウム−金属接合基板の製造方法において、前記砥粒は、ビッカース硬度が１０６０を超え、１８００以下であることが好ましい。 In the method for producing an aluminum nitride-metal bonded substrate according to the present invention, the abrasive grains preferably have a Vickers hardness of more than 1060 and 1800 or less.
本発明の窒化アルミニウム−金属接合基板の製造方法によれば、従来のホーニング処理では採用されなかった前記特定の条件と特定の砥粒を選定した砥粒スラリーの噴射により窒化アルミニウム焼結体基板表面を処理（以下、かかる処理を「湿式噴射処理」ともいう。）することにより、従来のホーニング処理では達成することのできない、高い抗折強度と高い耐熱サイクル特性を窒化アルミニウム−金属接合基板に付与することが可能となる。この現象は、かかる湿式噴射処理により窒化アルミニウム焼結体基板自体の強度が若干低下ことなどより、窒化アルミニウム焼結体基板の被処理面に何らかの変化が生じているものと推定される。 According to the manufacturing method of an aluminum nitride-metal bonded substrate of the present invention, the surface of the aluminum nitride sintered body substrate is sprayed by the abrasive slurry selected with the specific condition and the specific abrasive grain not adopted in the conventional honing process. (Hereinafter, this process is also referred to as “wet spraying process”) gives the aluminum nitride-metal bonded substrate high bending strength and high heat cycle characteristics that cannot be achieved by conventional honing processes. It becomes possible to do. This phenomenon is presumed to be caused by some change in the treated surface of the aluminum nitride sintered body substrate due to a slight decrease in the strength of the aluminum nitride sintered body substrate itself due to the wet spraying process.
また、本発明の方法は、後述するようにノズルから砥粒スラリーを噴出せしめるため、比較的広範囲に均一に処理を行うことができ、処理効率が良く、しかも、本発明の効果を再現性良く発揮することができるため、工業的な実施において有利である。 In addition, since the method of the present invention ejects the abrasive slurry from the nozzle as will be described later, the treatment can be performed uniformly over a relatively wide range, the processing efficiency is good, and the effect of the present invention is also reproducible. This is advantageous in industrial implementation.
以下、本発明を実施するための形態について説明する。 Hereinafter, modes for carrying out the present invention will be described.
（窒化アルミニウム焼結体）
本発明の製造方法で使用する窒化アルミニウム焼結体としては、入手の容易さや所望の形状のものを容易に得ることができるといった理由から窒化アルミニウム焼結体の平均結晶粒径が０．５〜２０μｍ、より好適には２〜７μｍの窒化アルミニウム焼結体を使用するのが好適である。このような窒化アルミニウム焼結体は、平均粒子径が０．１〜１５μｍ、好適には０．５〜５μｍの窒化アルミニウム原料粉末からなる成形体を焼成することにより得ることができる。
(Sintered aluminum nitride)
As the aluminum nitride sintered body used in the production method of the present invention, the average crystal grain size of the aluminum nitride sintered body is 0.5 to 0.5 because it can be easily obtained or obtained in a desired shape. It is preferable to use an aluminum nitride sintered body of 20 μm, more preferably 2 to 7 μm. Such an aluminum nitride sintered body can be obtained by firing a molded body made of an aluminum nitride raw material powder having an average particle diameter of 0.1 to 15 μm, preferably 0.5 to 5 μm.
上記成形体は、必要に応じて焼結助剤、有機バインダ等を含んでいてもよい。例えば、焼結助剤としては窒化アルミニウム原料粉末の種類に応じて常用される焼結助剤が特に制限なく使用できる。具体的には、酸化イットリウム（Ｙ２Ｏ３）、酸化エルビウム（Ｅｒ２Ｏ３）、酸化イッテルビウム（Ｙｂ２Ｏ３）などの希土類金属酸化物、Ｃａ、Ｂａ、Ｓｒなどのアルカリ土類金属元素の酸化物などが挙げられ、これらのうちでも特に酸化イットリウムを使用することが好ましい。希土類金属酸化物の配合量は、窒化アルミニウム焼結体粉末に対して１〜１０質量％の範囲とすることが好ましい。希土類酸化物の配合量が１０質量％を超えると、窒化アルミニウム焼結体の熱伝導率の低下などを招くおそれがある。一方、希土類酸化物の配合量が１質量％未満であると、窒化アルミニウム焼結体の焼結性が低下してポアの増大などを招くおそれがある。
また、有機バインダとしては、ポリビニルブチラール、エチルセルロース類やアクリル樹脂類が使用され、成形体の成形性が良好になるという理由からアクリル樹脂類、ポリビニルブチラールが特に好適に使用される。
The molded body may contain a sintering aid, an organic binder and the like as necessary. For example, as the sintering aid, a sintering aid that is commonly used depending on the type of aluminum nitride raw material powder can be used without particular limitation. Specifically, rare earth metal oxides such as yttrium oxide (Y 2 O 3 ), erbium oxide (Er 2 O 3 ), and ytterbium oxide (Yb 2 O 3 ), and alkaline earth metal elements such as Ca, Ba, and Sr Among these, it is particularly preferable to use yttrium oxide. The blending amount of the rare earth metal oxide is preferably in the range of 1 to 10% by mass with respect to the aluminum nitride sintered powder. If the blending amount of the rare earth oxide exceeds 10% by mass, the thermal conductivity of the aluminum nitride sintered body may be lowered. On the other hand, if the blending amount of the rare earth oxide is less than 1% by mass, the sinterability of the aluminum nitride sintered body may be reduced, leading to an increase in pores.
Further, as the organic binder, polyvinyl butyral, ethyl celluloses, and acrylic resins are used, and acrylic resins and polyvinyl butyral are particularly preferably used because the moldability of the molded article is improved.
本発明で使用する窒化アルミニウム焼結体の形状は、その上にＣｕ板などの金属基板が接合できるような表面を有するものであれば特に限定されず、板状体或いは板状体の一部に切削加工や穿孔加工を施したもの或いは曲面を有する焼結体でも使用することができる。 The shape of the aluminum nitride sintered body used in the present invention is not particularly limited as long as it has a surface on which a metal substrate such as a Cu plate can be bonded, and is a plate or a part of the plate It is also possible to use a sintered body having a curved surface or a curved surface, or a sintered body having a curved surface.
また、窒化アルミニウム焼結体の大きさは特に限定されず、表面に接合される金属基板の大きさに応じて適宜決定すればよい。 Further, the size of the aluminum nitride sintered body is not particularly limited, and may be appropriately determined according to the size of the metal substrate bonded to the surface.
更に、窒化アルミニウム焼結体の厚さは一般的には０．１〜２．０ｍｍ、好ましくは０．３〜１．５ｍｍ程度とすればよい。窒化アルミニウム焼結体基板の板厚が１．５ｍｍを超えると、熱抵抗が増大して熱サイクルが印加された際に金属基板の剥離などが生じやすくなる。また、窒化アルミニウム焼結体基板の板厚が０．３ｍｍ未満であると基板強度の劣化が大きくなると共に、窒化アルミニウム焼結体基板の絶縁耐圧が低下するなどによって、窒化アルミニウム焼結体−金属接合基板の信頼性が低下する。 Furthermore, the thickness of the aluminum nitride sintered body is generally 0.1 to 2.0 mm, preferably about 0.3 to 1.5 mm. When the plate thickness of the aluminum nitride sintered body substrate exceeds 1.5 mm, the thermal resistance is increased and the metal substrate is easily peeled off when a thermal cycle is applied. Further, when the thickness of the aluminum nitride sintered body substrate is less than 0.3 mm, the deterioration of the substrate strength is increased, and the dielectric breakdown voltage of the aluminum nitride sintered body substrate is lowered. The reliability of the bonded substrate is reduced.
また、窒化アルミニウム焼結体の表面粗さは特に制限されず、焼結後のそのままの表面であっても良いし、焼結の際に用いた離型材（ＢＮなど）などの付着物（異物）を除去する程度の清浄化加工、例えば、公知のホーニング処理のような表面加工を施した面であっても良いし、研削・研磨加工を施した面であっても良い。 In addition, the surface roughness of the aluminum nitride sintered body is not particularly limited, and the surface after sintering may be the same as it is, or deposits (foreign matter) such as a release material (BN, etc.) used during sintering For example, a surface subjected to surface processing such as a known honing process, or a surface subjected to grinding / polishing.
更にまた、本発明において使用する窒化アルミニウム焼結体は、常温での熱伝導率が１００Ｗ／ｍＫ以上、さらには１５０Ｗ／ｍＫ以上の放熱性を有していることが好ましい。窒化アルミニウム焼結体の熱伝導率が１００Ｗ／ｍＫ未満であると、半導体素子特にパワートランジスタのような高出力型の半導体素子やレーザ素子などを搭載する基板に求められる放熱性を確保することができず、各種電子素子の実装基板や回路基板などに窒化アルミニウム−金属接合基板を適用することの利点が損なわれてしまう。また、窒化アルミニウム焼結体は１０１２Ωｃｍ以上の体積抵抗率を有していることが好ましい。 Furthermore, the aluminum nitride sintered body used in the present invention preferably has a heat conductivity at room temperature of 100 W / mK or more, more preferably 150 W / mK or more. When the thermal conductivity of the aluminum nitride sintered body is less than 100 W / mK, it is possible to ensure the heat dissipation required for a substrate on which a semiconductor element, particularly a high-power semiconductor element such as a power transistor or a laser element is mounted. In other words, the advantage of applying the aluminum nitride-metal bonded substrate to a mounting board or circuit board for various electronic elements is impaired. The aluminum nitride sintered body preferably has a volume resistivity of 10 12 Ωcm or more.
（窒化アルミニウム焼結体基板の表面処理）
本発明の製造方法においては、窒化アルミニウム焼結体より高い硬度を有する砥粒を使用し、該低粒を１０〜３０体積％の濃度で含有する液体を、該窒化アルミニウム焼結体基板の被処理面にかかる圧力が０．００７〜０．０１２ＭＰａとなるようにノズルより噴射して該基板の表面を処理することが特徴である。
(Surface treatment of aluminum nitride sintered substrate)
In the production method of the present invention, abrasive grains having a hardness higher than that of the aluminum nitride sintered body are used, and a liquid containing the low grains at a concentration of 10 to 30% by volume is coated on the aluminum nitride sintered body substrate. The pressure applied to the processing surface is 0. 0 07-0. It is characterized in that the surface of the substrate is treated by spraying from a nozzle so as to be 0 12 MPa.
本発明で用いる砥粒の材質は、窒化アルミニウム焼結体より硬度が高いものであることが本発明の目的を達成するために必要である。即ち、砥粒の硬度が上記範囲より低い場合は、従来のホーニング処理と同様、窒化アルミニウム焼結体基板の表面の付着物の除去は可能であるが、後述する吹付条件との組み合わせによる表面改質が十分でなく、得られる接合体に高い抗折強度と高い耐熱サイクル特性を付与することが困難となる。 In order to achieve the object of the present invention, the material of the abrasive grains used in the present invention is higher in hardness than the aluminum nitride sintered body. That is, when the hardness of the abrasive grains is lower than the above range, it is possible to remove the deposits on the surface of the aluminum nitride sintered substrate as in the conventional honing treatment, but surface modification by combination with spraying conditions described later. The quality is not sufficient, and it becomes difficult to impart high bending strength and high heat cycle characteristics to the resulting bonded body.
砥粒の材質は、窒化アルミニウム焼結体基板の材質である、窒化アルミニウム焼結体より硬度が高いものであれば特に制限されないが、本発明の効果をより発揮するためには、窒化アルミニウム焼結体の硬度より、ピッカース硬度で、５０Ｈｖを超える硬度、好ましくは、１００Ｈｖ以上高い硬度のものが使用される。かかる砥粒の材質としては、アルミナ、ジルコニア、炭化ケイ素等を挙げることが出来る。中でも、アルミナが入手が容易であり、工業的に好ましい。 The material of the abrasive grains is not particularly limited as long as the material of the aluminum nitride sintered body is higher than that of the aluminum nitride sintered body, but in order to achieve the effects of the present invention, the aluminum nitride sintered body is not limited. A hardness having a picker hardness of more than 50 Hv, preferably 100 Hv or higher is used. Examples of the material of the abrasive grains include alumina, zirconia, and silicon carbide. Among these, alumina is easily available and industrially preferable.
また、前記砥粒の平均粒径は特に制限されないが、３０〜７０μｍ、好ましくは、４０〜６０μｍであることが好ましい。即ち、砥粒の粒径が小さすぎると接合基板の強度や熱サイクル特性を向上させる効果が小さくなる傾向にあり、一方、粒径が大きすぎると局所的な衝撃力が増大してダメージが大きくなる傾向がある。 The average particle size of the abrasive grains is not particularly limited, but is preferably 30 to 70 μm, and preferably 40 to 60 μm. That is, if the grain size of the abrasive grains is too small, the effect of improving the strength and thermal cycle characteristics of the bonded substrate tends to be reduced. On the other hand, if the grain size is too large, the local impact force increases and the damage increases. Tend to be.
本発明で用いる砥粒は、１０〜３０体積％の濃度で液体中に含有させた状態で使用される。かかる砥粒の濃度が１０体積％未満の場合、接合基板の抗折強度や熱サイクル特性を向上させる効果が不十分となり、砥粒の濃度が３０体積％を超えるとノズル孔に詰まりが生じやすくなったり、砥粒の循環不良が起こり易くなったりする。 The abrasive used in the present invention is used in a state of being contained in a liquid at a concentration of 10 to 30% by volume. When the concentration of the abrasive grains is less than 10% by volume, the effect of improving the bending strength and thermal cycle characteristics of the bonded substrate is insufficient, and when the concentration of the abrasive grains exceeds 30% by volume, the nozzle holes are easily clogged. Or poor circulation of the abrasive grains.
また、上記液体としては、砥粒を分散することが可能であれば、特に制限されない。例えば、水が代表的であるが、その他にも、アルコール等、有機溶媒の液体が使用可能である。 Further, the liquid is not particularly limited as long as abrasive grains can be dispersed. For example, water is typical, but in addition, an organic solvent liquid such as alcohol can be used.
本発明の製造方法において、前記砥粒スラリーは、該窒化アルミニウム焼結体基板の被処理面に掛かる圧力が０．００７〜０．０１２ＭＰａとなるように噴射することが前記目的を達成するために必要である。 In the production method of the present invention, the abrasive slurry has a pressure applied to the surface to be processed of the aluminum nitride sintered substrate of 0. 0 07-0. In order to achieve the above-mentioned purpose, it is necessary to inject such that the pressure is 0 to 12 MPa.
ここで、窒化アルミニウム焼結体基板の被処理面にかかる圧力とは、砥粒スラリーを加圧して、ノズルから噴射させた際の圧力を、被処理面の面積あたりに作用する圧力に換算した値である。具体的には、砥粒スラリーを加圧する圧力をＰ１［ＭＰａ］、砥粒スラリーが噴射されるノズルの開口面積をＳ１［ｍ２］、砥粒スラリーが作用する面積をＳ２［ｍ２］とした場合、被処理面の面積あたりに作用する圧力Ｐ２［ＭＰａ］は下記式で表わされる。
Ｐ２＝Ｐ１×Ｓ１／Ｓ２
上記被処理面の面積は、砥粒を含む流体が吹き付けられる窒化アルミニウム焼結体基板表面に形成された縞模様を実測することにより、求められる。
Here, the pressure applied to the surface to be processed of the aluminum nitride sintered body substrate is the pressure when the abrasive slurry is pressurized and sprayed from the nozzle is converted to the pressure acting on the area of the surface to be processed. Value. Specifically, the pressure for pressurizing the abrasive slurry is P 1 [MPa], the opening area of the nozzle through which the abrasive slurry is injected is S 1 [m 2 ], and the area where the abrasive slurry acts is S 2 [m 2 ], the pressure P 2 [MPa] acting per area of the surface to be processed is expressed by the following formula.
P 2 = P 1 × S 1 / S 2
The area of the surface to be treated can be obtained by actually measuring a striped pattern formed on the surface of the aluminum nitride sintered body substrate to which a fluid containing abrasive grains is sprayed.
尚、本発明の方法において、砥粒を含む液体の噴射に使用する装置は公知のブラスト機等の砥粒噴射装置が特に制限無く使用される。また、かかる装置におけるノズル孔の形状および数も特に制限されないが、処理による表面改質効果や生産性を考慮すると、ノズル孔の開口面積は２〜４ｍｍ２であることが好ましく、２．５〜３．５ｍｍ２であることがより好ましい。 In the method of the present invention, a known abrasive jetting device such as a blasting machine is used without particular limitation as the device used for jetting the liquid containing abrasive grains. Further, the shape and number of the nozzle holes in such an apparatus are not particularly limited, but considering the surface modification effect and productivity by treatment, the opening area of the nozzle holes is preferably 2 to 4 mm 2 , and 2.5 to More preferably, it is 3.5 mm 2 .
因みに、本発明の実施例において用いた処理装置では、Ｓ１となるノズル開口面積が３ｍｍ２に対して、Ｓ２となる窒化アルミニウム焼結体基板の被処理面に作用する面積は１５９ｍｍ２であった。 Incidentally, in the processing apparatus used in Examples of the present invention, the nozzle opening area is 3 mm 2 to be S 1, the area acting on the target surface of the S 2 become sintered aluminum nitride substrate is 159 mm 2 there were.
また、砥粒スラリーを窒化アルミニウム焼結体基板の被処理面に噴射する際のノズル−被処理面間距離については、１００ｍｍ以下であることが好ましく、特に５０ｍｍ以下であることがより好ましい。上記ノズル−被処理面間距離が１００ｍｍよりも大きくなると、被処理面にかかる圧力の分布にムラが生じやすくなったり、接合基板の強度や熱サイクル特性を向上させる効果が不十分となったりするおそれがある。 Further, the distance between the nozzle and the surface to be processed when spraying the abrasive slurry onto the surface to be processed of the aluminum nitride sintered substrate is preferably 100 mm or less, and more preferably 50 mm or less. When the distance between the nozzle and the surface to be processed is greater than 100 mm, unevenness in the pressure distribution on the surface to be processed is likely to occur, and the effect of improving the strength and thermal cycle characteristics of the bonded substrate may be insufficient. There is a fear.
本発明において、前記窒化アルミニウム焼結体基板の被処理面にかかる圧力が０．００７ＭＰａ未満の場合、被処理面における変異が十分でなく、窒化アルミニウム焼結体基板の若干の強度低下も起こらず、その結果、得られる接合基板の強度や耐熱サイクル特性を向上させる効果が不十分となる。一方、窒化アルミニウム焼結体基板の被処理面にかかる圧力が０．０１２ＭＰａを超えると、ノズルに破損が生じて生産性が低下したり、また、窒化アルミニウム焼結体基板の被処理面がダメージを受け過ぎ、例えば、接合強度自体の低下が生じる。 In the present invention, the pressure applied to the surface to be processed of the aluminum nitride sintered substrate is 0. When the pressure is less than 0.7 MPa, the surface to be processed is not sufficiently deformed, and the strength of the aluminum nitride sintered body substrate does not slightly decrease. As a result, the effect of improving the strength and heat cycle characteristics of the obtained bonded substrate is ineffective. It will be enough. On the other hand, the pressure applied to the surface to be processed of the aluminum nitride sintered substrate is 0. 0 exceeds 12 MPa, the productivity or decreased nozzle breakage occurs, also, only receiving the treated surface of the aluminum nitride sintered body substrate damage, for example, decrease in the joining strength itself occurs.
尚、本発明において、上記のような高い硬度を有する砥粒の砥粒スラリーを窒化アルミニウム焼結体基板の被処理面に噴射する方法に対して、空気など気体の加圧流体と共に砥粒を噴射して被処理面に吹き付ける方法は、被処理面において同等の圧力で処理しようとした場合、噴射速度が毎時１００ｋｍ以上となり、砥粒の速度が圧倒的に速いため、離型材などの異物の除去効率は向上するものの、焼結体表面に与えるダメージが大きくなり過ぎ、逆に金属基板を接合した後の耐熱サイクル特性が低下することが懸念される。また、空気など気体の加圧流体で砥粒を加速させる場合において、噴射速度を毎時１００ｋｍ以下にしようとすると、吐出ノズル先端部につまりが発生し易くなるばかりでなく、砥粒による深い当たり斑が発生する等、制御が困難となる。 In the present invention, in contrast to the method of injecting the abrasive slurry of abrasive grains having high hardness as described above onto the surface to be processed of the aluminum nitride sintered body substrate, the abrasive grains are used together with a pressurized fluid such as air. The method of spraying and spraying on the surface to be processed is such that when the processing surface is treated with the same pressure, the spraying speed becomes 100 km / h or more, and the abrasive speed is overwhelmingly high. Although the removal efficiency is improved, there is a concern that the damage given to the surface of the sintered body becomes too large, and conversely, the heat cycle characteristics after the metal substrate is bonded are deteriorated. In addition, when accelerating the abrasive grains with a pressurized fluid such as air, if the injection speed is set to 100 km / h or less, not only is the clogging easily generated at the tip of the discharge nozzle, but also the deep contact spots due to the abrasive grains. Control becomes difficult.
本発明において、前記砥粒スラリーを被処理面に噴射する時間（処理時間）は、一般に、１５秒〜６００秒であることが好ましく、１５秒〜２００秒であることがより好ましい。即ち、処理時間が１５秒よりも短い場合、得られる接合基板の強度や耐熱サイクル特性を向上させる効果が不十分となるおそれがある。一方、処理時間が６００秒を超えると生産性が低下することが懸念される。 In the present invention, the time for spraying the abrasive slurry onto the surface to be processed (processing time) is generally preferably from 15 seconds to 600 seconds, and more preferably from 15 seconds to 200 seconds. That is, when the processing time is shorter than 15 seconds, the effect of improving the strength and heat cycle characteristics of the obtained bonded substrate may be insufficient. On the other hand, when the processing time exceeds 600 seconds, there is a concern that the productivity is lowered.
また、上記処理を施す際は、窒化アルミニウム焼結体基板は固定された状態である必要はなく、窒化アルミニウム焼結体基板表面の全面を効率良く、且つ、ムラなく処理するために、複数のノズルが予め配置された処理ゾーンを、該窒化アルミニウム焼結体基板をベルトコンベアなどによって搬送させても良い。また、前記処理は窒化アルミニウム焼結体基板の片面だけを行っても良いし、あるいは、片面ずつを交互に処理して両面を処理しても良く、両面同時に行っても良い。また、窒化アルミニウム焼結体を固定した状態で、ノズルを移動させることによって高速湿式処理を行っても良い。 Further, when performing the above treatment, the aluminum nitride sintered body substrate does not need to be in a fixed state, and in order to efficiently and uniformly treat the entire surface of the aluminum nitride sintered body substrate surface, a plurality of The aluminum nitride sintered body substrate may be transported by a belt conveyor or the like in a processing zone in which nozzles are arranged in advance. Moreover, the said process may perform only one side of an aluminum nitride sintered compact board | substrate, or may process both sides by processing one side alternately, and may perform both sides simultaneously. Alternatively, high-speed wet processing may be performed by moving the nozzle while the aluminum nitride sintered body is fixed.
（金属基板の接合）
本発明において、前記砥粒スラリーを噴射して被処理面を改質された窒化アルミニウム焼結体基板は、かかる被処理表面上に金属基板を接合することによって、窒化アルミニウム焼結体−金属接合基板が得られる。また、前記したように、窒化アルミニウム焼結体基板の処理表面の表面粗さは、ＪＩＳ Ｂ０６０１−１９９４で規定される算術平均粗さＲａで１．０μｍ以下であることが好ましい。窒化アルミニウム焼結体基板の処理表面の表面粗さＲａが１．０μｍを超えると、金属基板との接合強度の低下などを招くおそれがある。
(Metal substrate bonding)
In the present invention, the aluminum nitride sintered body substrate whose surface to be treated has been modified by spraying the abrasive slurry is joined to the aluminum nitride sintered body-metal joint by joining the metal substrate onto the surface to be treated. A substrate is obtained. As described above, the surface roughness of the treated surface of the aluminum nitride sintered body substrate is preferably 1.0 μm or less in terms of arithmetic average roughness Ra defined by JIS B0601-1994. If the surface roughness Ra of the treated surface of the aluminum nitride sintered body substrate exceeds 1.0 μm, the bonding strength with the metal substrate may be lowered.
窒化アルミニウム焼結体−金属接合基板を構成する金属基板は、接合基板の使用用途や使用形態などに応じて適宜に選択されるものであり、例えばＣｕもしくはＣｕ合金板、ＡｌもしくはＡｌ合金板、ＮｉもしくはＮｉ合金板などが使用される。ただし、金属基板はこれらに限定されるものではなく、必要に応じてＷやＭｏなどの高融点金属との合金やクラッド材などを使用してもよい。特に、接合法に活性金属法を適用する場合には、各種の金属材料からなる金属基板を窒化アルミニウム焼結体基板に接合することが可能である。 本発明において、前記金属基板は０．２〜０．４ｍｍの範囲の厚さを有することが好ましい。また、金属基板は回路構造を有しているもの、あるいは単純な板状のいずれでもよい。 The metal substrate constituting the aluminum nitride sintered body-metal bonded substrate is appropriately selected according to the use application or usage of the bonded substrate, for example, a Cu or Cu alloy plate, an Al or Al alloy plate, Ni or a Ni alloy plate is used. However, the metal substrate is not limited to these, and an alloy with a refractory metal such as W or Mo or a clad material may be used as necessary. In particular, when the active metal method is applied to the bonding method, a metal substrate made of various metal materials can be bonded to the aluminum nitride sintered body substrate. In the present invention, the metal substrate preferably has a thickness in the range of 0.2 to 0.4 mm. Further, the metal substrate may have either a circuit structure or a simple plate shape.
なお、前記説明では、便宜的に窒化アルミニウム焼結体基板の一方の基板面のみに金属基板を接合した状態を示したが、窒化アルミニウム焼結体基板の両面に金属基板を接合することもできる。 In the above description, the state in which the metal substrate is bonded to only one surface of the aluminum nitride sintered substrate is shown for convenience, but the metal substrate can also be bonded to both surfaces of the aluminum nitride sintered substrate. .
窒化アルミニウム焼結体基板と金属基板との接合方法は、必ずしも限定されるものではないが、活性金属ろう材層を用いた接合方法を適用することが好ましい。活性金属ろう材層を用いた接合方法（活性金属法）においては、基板表面の性状が接合基板の強度や熱サイクル特性などに対して大きな影響を及ぼすことから、特に本発明の製造方法を適用することで健全な窒化アルミニウム焼結体−金属接合基板を得ることができる。活性金属法以外には、窒化アルミニウム焼結体基板とＣｕ板とを加熱処理により直接接合するＤＢＣ法を適用することも可能であるが、ＤＢＣ法の場合には窒化アルミニウム焼結体基板の表面に酸化膜を形成することが一般的であるため、基板表面の性状がそれほど影響しない。このように、本発明は活性金属法を適用した窒化アルミニウム焼結体−金属接合基板の製造方法に対して好適である。 The joining method of the aluminum nitride sintered body substrate and the metal substrate is not necessarily limited, but a joining method using an active metal brazing material layer is preferably applied. In the joining method (active metal method) using the active metal brazing material layer, the manufacturing method of the present invention is particularly applied because the properties of the substrate surface have a great influence on the strength and thermal cycle characteristics of the joined substrate. By doing so, a sound aluminum nitride sintered body-metal bonded substrate can be obtained. In addition to the active metal method, it is also possible to apply the DBC method in which the aluminum nitride sintered body substrate and the Cu plate are directly joined by heat treatment, but in the case of the DBC method, the surface of the aluminum nitride sintered body substrate Since it is common to form an oxide film, the properties of the substrate surface are not so affected. Thus, this invention is suitable with respect to the manufacturing method of the aluminum nitride sintered compact-metal joining board | substrate which applied the active metal method.
活性金属ろう材層には、例えばＴｉ、Ｚｒ、Ｈｆ、Ｎｂ、Ａｌなどから選ばれる少なくとも１種の活性金属を、Ａｇ−Ｃｕの共晶組成（７２ｗｔ％Ａｇ−２８ｗｔ％Ｃｕ）もしくはその近傍組成のＡｇ−Ｃｕ系ろう材やＣｕ系ろう材などのろう材成分に配合した活性金属ろう材を適用することが好ましい。活性金属ろう材中の活性金属量は、ろう材の全量に対して０．５〜１０重量％の範囲とすることが好ましい。活性金属ろう材は適量のＳｎやＩｎ（例えばろう材の全量に対して２〜７重量％）などを含んでいてもよい。このような活性金属ろう材の塗布層などを介して窒化アルミニウム焼結体基板と金属基板とを積層し、この積層物を例えば７００〜９００℃程度の温度で熱処理することによって、窒化アルミニウム焼結体−金属接合基板が得られる。接合時の熱処理は不活性雰囲気中や真空中で実施することが好ましい。 For the active metal brazing material layer, for example, at least one active metal selected from Ti, Zr, Hf, Nb, Al, etc. is used, an Ag—Cu eutectic composition (72 wt% Ag-28 wt% Cu) or a composition in the vicinity thereof. It is preferable to apply an active metal brazing material blended with a brazing filler metal component such as an Ag-Cu brazing filler metal or a Cu brazing filler metal. The amount of active metal in the active metal brazing material is preferably in the range of 0.5 to 10% by weight with respect to the total amount of the brazing material. The active metal brazing material may contain an appropriate amount of Sn or In (for example, 2 to 7% by weight based on the total amount of the brazing material). An aluminum nitride sintered body substrate and a metal substrate are laminated through such an active metal brazing material coating layer, and the laminate is heat-treated at a temperature of about 700 to 900 ° C., for example. A body-metal bonded substrate is obtained. The heat treatment at the time of bonding is preferably performed in an inert atmosphere or in a vacuum.
上述したような製造方法により得られる窒化アルミニウム焼結体−金属接合基板は、窒化アルミニウム焼結体基板の基板表面、すなわち湿式噴射処理を施した処理面の性状に基づいて、高接合強度と優れた耐熱サイクル特性を有するものである。 The aluminum nitride sintered body-metal bonded substrate obtained by the manufacturing method as described above is based on the properties of the substrate surface of the aluminum nitride sintered substrate, that is, the treated surface that has been subjected to the wet spraying process. It has excellent heat cycle characteristics.
次に、本発明の具体的な実施例およびその評価結果について述べる。 Next, specific examples of the present invention and evaluation results thereof will be described.
尚、後述の実施例および比較例において、金属基板接合前の表面改質窒化アルミニウム焼結体基板について、まず表面粗さおよび曲げ強度を測定した。窒化アルミニウム焼結体基板の抗折強度は１０枚（ｎ＝１０）の窒化アルミニウム焼結体に対して、３点曲げ試験を行い、その平均値にて評価した。 In Examples and Comparative Examples described later, the surface roughness and bending strength of the surface-modified aluminum nitride sintered body substrate before joining the metal substrate were first measured. The bending strength of the aluminum nitride sintered body substrate was evaluated by an average value of a three-point bending test performed on 10 (n = 10) aluminum nitride sintered bodies.
次に、窒化アルミニウム−金属接合基板については、熱サイクル後の窒化アルミニウム−金属接合基板の抗折強度の測定、および、熱サイクル特性の測定、評価を実施した。熱サイクル後の窒化アルミニウム−金属接合基板の抗折強度は、１０枚（ｎ＝１０）の該接合基板に対して、３８０℃×１０分を１サイクルとする熱サイクル試験を３回繰返した後の３点曲げ試験を行い、その平均値にて評価した。 Next, the aluminum nitride-metal bonded substrate was subjected to measurement of the bending strength of the aluminum nitride-metal bonded substrate after thermal cycling, and measurement and evaluation of thermal cycle characteristics. The bending strength of the aluminum nitride-metal bonded substrate after the thermal cycle is 10 times (n = 10) after repeating the thermal cycle test with 1 cycle of 380 ° C. × 10 minutes for 3 times. The three-point bending test was conducted, and the average value was evaluated.
また、熱サイクル特性は、１０枚の窒化アルミニウム焼結体−Ｃｕ接合基板に対して、３８０℃×１０分を１サイクルとする熱サイクル試験を３５回繰返した後、クラックの発生枚数に基づく合格率により評価した。 In addition, the thermal cycle characteristics were passed based on the number of cracks generated after 35 cycles of a thermal cycle test of 10 cycles of 380 ° C. × 10 minutes for 10 aluminum nitride sintered body-Cu bonded substrates. The rate was evaluated.
熱サイクル特性評価の合格率が１００％であるということはクラックの発生が皆無であることを意味し、一方合格率が０％であるということは窒化アルミニウム焼結体基板の全数にクラックが発生していたことを意味する。 A pass rate of 100% for thermal cycle characteristics evaluation means that no cracks are generated. On the other hand, a pass rate of 0% means that all the aluminum nitride sintered substrates have cracks. It means that I was doing.
実施例１
まず、平均粒径が１．０μｍの窒化アルミニウム粉末に対して、焼結助剤として平均粒径が１．０μｍのＹ２Ｏ３粉末を５．０質量部加え、さらに適量の有機バインダと溶媒などを加えて混合してスラリー状とした。この原料スラリーをドクターブレード法により板状に成形した。このような窒化アルミニウム成形体を複数枚用意し、これら複数枚の窒化アルミニウム成形体を各成形体間にＢＮ粉（離型材）を介在させて重ね合わせた。
Example 1
First, 5.0 parts by mass of Y 2 O 3 powder having an average particle diameter of 1.0 μm as a sintering aid is added to aluminum nitride powder having an average particle diameter of 1.0 μm, and an appropriate amount of an organic binder and a solvent. Etc. were added and mixed to form a slurry. This raw material slurry was formed into a plate shape by the doctor blade method. A plurality of such aluminum nitride molded bodies were prepared, and the plurality of aluminum nitride molded bodies were overlapped with BN powder (release material) interposed between the molded bodies.
この状態で、この窒化アルミニウム成形体を５３０℃の温度で脱脂した。次に、脱脂後のこれら窒化アルミニウム脱脂体を窒素ガス雰囲気中にて１７６０℃×５時間の条件で焼成することによって、窒化アルミニウム焼結体基板（熱伝導率＝１７０Ｗ／ｍＫ、体積抵抗率＝１０１２Ωｃｍ、板厚０．６３５ｍｍ）を作製した。 In this state, the aluminum nitride molded body was degreased at a temperature of 530 ° C. Next, these aluminum nitride degreased bodies after degreasing are fired under a condition of 1760 ° C. × 5 hours in a nitrogen gas atmosphere, whereby an aluminum nitride sintered body substrate (thermal conductivity = 170 W / mK, volume resistivity = 10 12 Ωcm, plate thickness 0.635 mm).
次いで、得られた窒化アルミニウム焼結体の両面（全表面）に、砥粒スラリーとして、平均粒径が５０μｍ（粒度＝♯２８０）のアルミナ（組成：Ａｌ２Ｏ３）砥粒が２０体積％の濃度で含有された水を、０．５ＭＰａの圧力で加圧し、該窒化アルミニウム焼結体被処理面にかかる圧力が０．００９ＭＰａとなるようにノズルより噴出せしめることにより、焼結体表面を１００秒間、湿式噴射処理することによって表面改質窒化アルミニウム焼結体基板を得た。 Next, 20% by volume of alumina (composition: Al 2 O 3 ) abrasive grains having an average particle size of 50 μm (grain size = # 280) as abrasive slurry on both surfaces (all surfaces) of the obtained aluminum nitride sintered body. The water contained at a concentration of 0.5 MPa was pressurized at a pressure of 0.5 MPa, and the pressure applied to the treated surface of the aluminum nitride sintered body was 0. The surface-modified aluminum nitride sintered body substrate was obtained by performing a jet injection process for 100 seconds on the surface of the sintered body by ejecting from the nozzle so that the pressure became 0 09 MPa.
次に、上記表面改質窒化アルミニウム焼結体基板の両面に活性金属ろう材ペーストを塗布した後、厚さ０．３ｍｍのＣｕ板をそれぞれ配置し、この積層物を真空雰囲気中にて８００℃×０．５時間の条件で熱処理して、窒化アルミニウム焼結体基板とＣｕ板とを活性金属ろう材を介して接合することによって、目的とする窒化アルミニウム焼結体−Ｃｕ接合基板を得た。このような窒化アルミニウム焼結体−Ｃｕ接合基板を後述する特性評価に供した。 Next, after applying an active metal brazing paste on both surfaces of the surface-modified aluminum nitride sintered body substrate, a Cu plate having a thickness of 0.3 mm is disposed, and this laminate is placed in a vacuum atmosphere at 800 ° C. Heat treatment was performed under the conditions of × 0.5 hours, and the target aluminum nitride sintered body-Cu bonded substrate was obtained by bonding the aluminum nitride sintered body substrate and the Cu plate via the active metal brazing material. . Such an aluminum nitride sintered body-Cu bonded substrate was subjected to the characteristic evaluation described later.
なお、活性金属ろう材ペーストにはＴｉを４．０質量％含有するＡｇ−Ｃｕ共晶ろう材（活性金属ろう材）に適量の有機バインダと溶媒を加えてペースト化したものを使用し、このような活性金属ろう材ペーストを塗布厚が３０μｍとなるように、表面改質窒化アルミニウム焼結体基板の両面にスクリーン印刷した。 In addition, the active metal brazing material paste used is an Ag-Cu eutectic brazing material (active metal brazing material) containing 4.0% by mass of Ti, which is made into a paste by adding an appropriate amount of an organic binder and a solvent. Such an active metal brazing paste was screen-printed on both surfaces of the surface-modified aluminum nitride sintered substrate so that the coating thickness was 30 μm.
実施例２
上述した実施例１において、窒化アルミニウム焼結体基板の湿式噴射処理に、アルミナ砥粒が含有された水を０．４ＭＰａの圧力で加圧し、窒化アルミニウム焼結体の被処理面にかかる圧力が０．００８ＭＰａとなるようにした以外は、実施例１と同様に窒化アルミニウム焼結体−Ｃｕ接合基板を作製した。
Example 2
In Example 1 described above, water containing alumina abrasive grains is pressurized at a pressure of 0.4 MPa in the wet jet treatment of the aluminum nitride sintered body substrate, and the pressure applied to the treated surface of the aluminum nitride sintered body is increased. 0. An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure was set at 0 08 MPa.
比較例１
上述した実施例１において、窒化アルミニウム焼結体の湿式噴射処理に、アルミナ砥粒が含有された水を０．３ＭＰａの圧力で加圧し、窒化アルミニウム焼結体の被処理面にかかる圧力が０．００６ＭＰａとなるようにした以外は、実施例１と同様に窒化アルミニウム焼結体−Ｃｕ接合基板を作製した。
Comparative Example 1
In Example 1 described above, water containing alumina abrasive grains is pressurized at a pressure of 0.3 MPa in the wet jet treatment of the aluminum nitride sintered body, and the pressure applied to the treated surface of the aluminum nitride sintered body is 0. . Except that as a 0 06MPa was prepared sintered aluminum -Cu bonded substrate nitride in the same manner as in Example 1.
比較例２
上述した実施例１において、窒化アルミニウム焼結体の湿式噴射処理に、アルミナ砥粒が含有された水を０．２ＭＰａの圧力で加圧し、窒化アルミニウム焼結体の被処理面にかかる圧力が０．００４ＭＰａとなるようにした以外は、実施例１と同様に窒化アルミニウム焼結体−Ｃｕ接合基板を作製した。
Comparative Example 2
In Example 1 described above, water containing alumina abrasive grains was pressurized at a pressure of 0.2 MPa in the wet jet treatment of the aluminum nitride sintered body, and the pressure applied to the treated surface of the aluminum nitride sintered body was 0. . Except that as a 0 04MPa was prepared sintered aluminum -Cu bonded substrate nitride in the same manner as in Example 1.
比較例３
上述した実施例１において、窒化アルミニウム焼結体の湿式噴射処理に、平均粒径６０μｍのジルコン砥粒を用い、ジルコン砥粒が含有された水を０．４ＭＰａの圧力で加圧し、窒化アルミニウム焼結体の被処理面にかかる圧力が０．００８ＭＰａとなるようにした以外は、実施例１と同様に窒化アルミニウム焼結体−Ｃｕ接合基板を作製した。
Comparative Example 3
In Example 1 described above, the aluminum nitride sintered body was wet sprayed using zircon abrasive grains having an average particle diameter of 60 μm, and water containing the zircon abrasive grains was pressurized at a pressure of 0.4 MPa, and the aluminum nitride firing was performed. The pressure applied to the surface to be treated of the bonded body is 0. An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure was set at 0 08 MPa.
比較例４
上述した実施例１において、窒化アルミニウム焼結体の湿式噴射処理に、平均粒径６０μｍのジルコン砥粒を用い、ジルコン砥粒が含有された水を０．２ＭＰａの圧力で加圧し、窒化アルミニウム焼結体の被処理面にかかる圧力が０．００４ＭＰａとなるようにした以外は、実施例１と同様に窒化アルミニウム焼結体−Ｃｕ接合基板を作製した。
Comparative Example 4
In Example 1 described above, the aluminum nitride sintered body was wet sprayed using zircon abrasive grains having an average particle diameter of 60 μm, and water containing zircon abrasive grains was pressurized at a pressure of 0.2 MPa, so The pressure applied to the surface to be treated of the bonded body is 0. Except that as a 0 04MPa was prepared sintered aluminum -Cu bonded substrate nitride in the same manner as in Example 1.
比較例５
上述した実施例１において、窒化アルミニウム焼結体基板の湿式噴射処理の代わりに敷粉を除去する目的で超音波水洗を実施したこと、および、超音波水洗後の窒化アルミニウム焼結体基板とＣｕ板を活性金属ろう材を介して接合しなかったこと以外は、実施例１と同様に窒化アルミニウム焼結体を作製した。
Comparative Example 5
In Example 1 described above, ultrasonic water washing was carried out for the purpose of removing bed powder instead of wet spraying treatment of the aluminum nitride sintered body substrate, and the aluminum nitride sintered body substrate and Cu after ultrasonic water washing were performed. An aluminum nitride sintered body was produced in the same manner as in Example 1 except that the plate was not joined via the active metal brazing material.
比較例６
上述した実施例１において、窒化アルミニウム焼結体基板の湿式噴射処理を実施せずにラップ研磨を実施したこと、および、ラップ研磨後の窒化アルミニウム焼結体基板とＣｕ板を活性金属ろう材を介して接合しなかったこと以外は、実施例１と同様に窒化アルミニウム焼結体を作製した。
Comparative Example 6
In Example 1 described above, lapping was performed without performing wet spraying of the aluminum nitride sintered body substrate, and the active metal brazing material was used for the aluminum nitride sintered body substrate and the Cu plate after lapping. An aluminum nitride sintered body was produced in the same manner as in Example 1 except that the aluminum nitride sintered body was not joined.
表１に示したように、実施例１、２による窒化アルミニウム焼結体は、被処理物である窒化アルミニウムよりも硬度の高いアルミナ砥粒を、従来よりも高い衝撃力で衝突させているため、表面粗さが小さくなっていることが分かる。また、実施例１、２による窒化アルミニウム焼結体−Ｃｕ接合基板は、窒化アルミニウム焼結体表面の改質効果も高いため窒化アルミニウム焼結体−Ｃｕ接合基板の抗折強度および熱サイクル特性が優れていることが分かる。一方、弱い衝撃力でアルミナ砥粒を衝突させて湿式噴射処理を実施した比較例１、２では、窒化アルミニウム焼結体表面の改質効果が低いため窒化アルミニウム焼結体−Ｃｕ接合基板の抗折強度および熱サイクル特性が共に劣っている。更に、窒化アルミニウムよりも硬度の低いジルコン砥粒を用いて湿式噴射処理を行った比較例３、４においては、窒化アルミニウム焼結体表面の表面粗さが大きく、窒化アルミニウム焼結体−Ｃｕ接合基板の抗折強度および熱サイクル特性の向上が不十分となっていることが分かる。 As shown in Table 1, since the aluminum nitride sintered bodies according to Examples 1 and 2 collide with alumina abrasive grains having a hardness higher than that of aluminum nitride as an object to be processed with a higher impact force than before. It can be seen that the surface roughness is reduced. In addition, since the aluminum nitride sintered body-Cu bonded substrate according to Examples 1 and 2 has a high modification effect on the surface of the aluminum nitride sintered body, the bending strength and thermal cycle characteristics of the aluminum nitride sintered body-Cu bonded substrate are high. It turns out that it is excellent. On the other hand, in Comparative Examples 1 and 2 in which the wet abrasive treatment was performed by causing the alumina abrasive grains to collide with a weak impact force, the effect of modifying the surface of the aluminum nitride sintered body was low, so the resistance of the aluminum nitride sintered body to the Cu bonded substrate was low. Both folding strength and thermal cycle characteristics are inferior. Furthermore, in Comparative Examples 3 and 4 in which the wet jet treatment was performed using zircon abrasive grains having a hardness lower than that of aluminum nitride, the surface roughness of the aluminum nitride sintered body was large, and the aluminum nitride sintered body-Cu joint It can be seen that the bending strength and thermal cycle characteristics of the substrate are insufficiently improved.
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