JPH0352128B2 - - Google Patents
Info
- Publication number
- JPH0352128B2 JPH0352128B2 JP60206791A JP20679185A JPH0352128B2 JP H0352128 B2 JPH0352128 B2 JP H0352128B2 JP 60206791 A JP60206791 A JP 60206791A JP 20679185 A JP20679185 A JP 20679185A JP H0352128 B2 JPH0352128 B2 JP H0352128B2
- Authority
- JP
- Japan
- Prior art keywords
- alumina
- substrate
- film
- less
- polishing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000758 substrate Substances 0.000 claims description 89
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 53
- 238000000034 method Methods 0.000 claims description 24
- 230000003746 surface roughness Effects 0.000 claims description 22
- 229910010293 ceramic material Inorganic materials 0.000 claims description 15
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 239000000843 powder Substances 0.000 claims description 6
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 4
- 239000000725 suspension Substances 0.000 claims description 4
- 239000010408 film Substances 0.000 description 43
- 238000005498 polishing Methods 0.000 description 31
- 239000000463 material Substances 0.000 description 15
- 239000000919 ceramic Substances 0.000 description 13
- 229910000838 Al alloy Inorganic materials 0.000 description 12
- 238000004544 sputter deposition Methods 0.000 description 12
- 239000010409 thin film Substances 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 239000013078 crystal Substances 0.000 description 9
- 230000007797 corrosion Effects 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- 239000000956 alloy Substances 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 238000001513 hot isostatic pressing Methods 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 238000003754 machining Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000007606 doctor blade method Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000003966 growth inhibitor Substances 0.000 description 1
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Manufacturing Of Magnetic Record Carriers (AREA)
- Magnetic Record Carriers (AREA)
Description
【発明の詳細な説明】
利用産業分野
この発明は、セラミツクス材料からなる磁気デ
イスク用基板に係り、表面が無孔・無歪アルミナ
スパツタ層からなり、すぐれた表面粗度を有する
磁気デイスク用基板並びにその製造方法に関す
る。Detailed Description of the Invention Field of Application The present invention relates to a magnetic disk substrate made of ceramic material, the surface of which is made of a non-porous, non-strained alumina spattered layer and has excellent surface roughness. and its manufacturing method.
背景技術
一般に、磁気デイスク用基板としては、次のよ
うな特性が要求される。BACKGROUND ART In general, magnetic disk substrates are required to have the following characteristics.
(1) 0.3μｍ以下の低い磁気ヘツド浮上高さに伴な
い磁気ヘツドの安定な浮上と記録特性の安定性
を得るため、研摩後の基板表面粗度がすぐれて
いること、
(2) 基板表面に形成される磁性薄膜の欠陥の要因
となる突起や孔状のへこみがないこと、
(3) 機械加工、研摩あるいは使用時の高速・回転
に十分耐える機械的強度を有すること、
(4) 耐食性、耐候性、及び耐熱性にすぐれるこ
と。(1) The substrate surface roughness after polishing must be excellent in order to achieve stable flying of the magnetic head and stability of recording characteristics due to the low magnetic head flying height of 0.3 μm or less; (2) The substrate surface (3) have sufficient mechanical strength to withstand machining, polishing, or high-speed rotation during use; (4) corrosion resistance. , excellent weather resistance, and heat resistance.
従来、磁気デイスク用基板には、アルミニウム
合金が使用されているが、アルミニウム合金基板
では、材料の結晶異方性、材料欠陥及び材料中に
存在する非金属介在物等のため、機械加工や研摩
加工において、非金属介在物が基板表面に突起と
して残存したり、あるいは脱落して凹みを生じ、
十分研摩を施しても精々200Å程度の表面粗度し
か得られず、突起や凹み、うねりのある表面状態
では、高密度磁気記録用磁気デイスク用基板材と
しては十分でない。 Conventionally, aluminum alloys have been used for magnetic disk substrates, but aluminum alloy substrates require machining and polishing due to the crystal anisotropy of the material, material defects, and nonmetallic inclusions present in the material. During processing, nonmetallic inclusions may remain on the substrate surface as protrusions or fall off, creating dents.
Even if sufficient polishing is performed, a surface roughness of only about 200 Å can be obtained at most, and a surface condition with protrusions, depressions, and undulations is not sufficient as a substrate material for a magnetic disk for high-density magnetic recording.
すなわち、磁気デイスク基板表面の加工の良否
が、そのまま、磁気デイスクのランアウト、加速
度成分、媒体の信号エラー等に影響するのであ
る。 In other words, the quality of the processing of the surface of the magnetic disk substrate directly affects the runout of the magnetic disk, the acceleration component, the signal error of the medium, and the like.
ところで、アルミニウム合金の基板の場合、金
属材料のため、ビツカース硬度も100Kg／mm2程度
（セラミツクの場合600Kg／mm2以上）であり、曲げ
強度も1000Kg／cm2（セラミツクの場合4000Kg／cm2
以上）であつて、高密度磁気記録となるに従つ
て、スクラツチ、疵、平坦度、うねりなどの形状
精度も厳しくなるため、加工は一層困難となつて
いる。 By the way, in the case of an aluminum alloy substrate, since it is a metal material, its Vickers hardness is around 100Kg/mm 2 (over 600Kg/mm 2 for ceramics), and its bending strength is 1000Kg/cm 2 (4000Kg/cm 2 for ceramics).
(above), and as high-density magnetic recording becomes available, shape accuracy such as scratches, flaws, flatness, and waviness becomes more severe, making processing even more difficult.
また、アルミニウム合金基板の場合、砥粒加工
の際に、砥粒が表面凹みに埋め込まれやすく、欠
陥となり、さらに、表面の耐食性、耐候性を高め
て汚染を防ぐ上で、旋削工程、ポリツシング工
程、保管の際、清浄度、防錆、汚れ等には十分な
配慮が必要となる。 In addition, in the case of aluminum alloy substrates, during abrasive processing, abrasive grains tend to become embedded in surface dents, resulting in defects.Furthermore, in order to improve the corrosion resistance and weather resistance of the surface and prevent contamination, When storing, sufficient consideration must be given to cleanliness, rust prevention, dirt, etc.
アルミニウム合金基板の改善のため、その表面
に高硬度の膜を形成する方法が提案されており、
例えば、アルミニウム合金基板表面にアルマイト
層を形成して硬度を増加させ、研摩加工性を向上
させる方法が取られるが、アルマイト形成中にア
ルミニウム合金中の微量不純物（Fe、Mn、Si）
が金属間化合物として析出するため、アルマイト
処理後、上記化合物部分が凹みの発生要因となつ
ている。 In order to improve aluminum alloy substrates, a method has been proposed to form a highly hard film on the surface.
For example, an alumite layer is formed on the surface of an aluminum alloy substrate to increase hardness and improve polishability, but trace impurities (Fe, Mn, Si) in the aluminum alloy are formed during alumite formation.
is precipitated as an intermetallic compound, so after the alumite treatment, the above-mentioned compound portion is the cause of the formation of dents.
また、アルミニウム合金母材の高純度化を計る
ことは、製造工程上至難に近く、さらに、耐食
性、清浄度の面でも取り扱いが問題となる。 In addition, achieving high purity of the aluminum alloy base material is almost extremely difficult in terms of the manufacturing process, and handling also poses problems in terms of corrosion resistance and cleanliness.
また、アルミニウム合金表面へのスパツタリン
グやメツキによつて薄膜磁性媒体を形成する場
合、該合金と磁性膜との化学反応や拡散の問題を
生じ、更に、磁性膜被着時の熱処理により、基板
の変形と共に基板回転時の面振れ、加速度が増加
する問題がある。 Furthermore, when a thin film magnetic medium is formed by sputtering or plating on the surface of an aluminum alloy, problems arise such as chemical reaction and diffusion between the alloy and the magnetic film, and furthermore, heat treatment during the deposition of the magnetic film may cause the substrate to deteriorate. Along with the deformation, there is a problem that surface runout and acceleration increase when the substrate is rotated.
一方、アルミニウム合金基板上に、SiO2、
Al2O3等の酸化物をスパツタリングによつて形成
する方法も提案されているが、該合金基板とスパ
ツタ形成後の被膜との密着力が弱いという欠点が
あつた。 On the other hand, on the aluminum alloy substrate, SiO 2 ,
A method of forming oxides such as Al 2 O 3 by sputtering has also been proposed, but this method has the disadvantage that the adhesion between the alloy substrate and the coating after sputtering is weak.
今日、アルミナ系セラミツク材料が、アルミニ
ウム合金材料に比べて、耐熱性、耐摩耗性、耐候
性、絶縁性、及び機械的強度のすぐれているた
め、各種分野の広範囲な用途に利用されている
が、磁気デイスク用基板としては、基板表面に薄
膜磁性媒体を形成する必要並びに、媒体の薄膜
化、高密度化に伴ない、アルミナ系セラミツク基
板表面の無孔化・無歪化を計ることが切望されて
いる。 Today, alumina ceramic materials are used for a wide range of applications in various fields because they have superior heat resistance, wear resistance, weather resistance, insulation properties, and mechanical strength compared to aluminum alloy materials. As substrates for magnetic disks, it is necessary to form a thin magnetic medium on the surface of the substrate, and as media become thinner and more dense, it is strongly desired to make the surface of the alumina ceramic substrate free of pores and distortion. has been done.
一般に、セラミツク基板の製造方法として、単
結晶法、金型成形、ラバープレス、ドクターブレ
ード法等により成形後に焼結する方法、さらに高
密度化のため、ホツトプレス法、熱間静水圧プレ
ス法が知られているが、前者の単結晶化法では製
造コストが高い上に、大口径基板の製造が困難で
あり、また、後者のホツトプレスや熱間静水圧プ
レスにより高密度化された基板であつても、5μ
ｍ以下の微細孔が基板に存在するため、磁気デイ
スク用基板に要することは、表面微細欠陥による
ドロツプアウトの発生、ヘツドクラツシユ等の信
頼性とを損う等の問題があつた。 In general, methods for manufacturing ceramic substrates include methods such as single crystal method, mold forming, rubber press, doctor blade method, etc. to form and sinter, and for higher density, hot press method and hot isostatic pressing method. However, the former single crystallization method has high production costs and is difficult to manufacture large-diameter substrates, and the latter method requires high density substrates using hot pressing or hot isostatic pressing. Also, 5μ
Since micropores of less than m in size exist in the substrate, the substrate for magnetic disks has problems such as occurrence of dropouts due to microscopic defects on the surface and loss of reliability of head crushing and the like.
また、一般に、磁気デイスク基板等に適用し得
る表面研摩法として、メカノケミカル研摩法は、
シリコン基板、GGG結晶、フエライト等の表面
物性を劣化させることなく精密表面に仕上げる方
法として公知であるが、微細孔の存在するセラミ
ツク材料にこのメカノケミカル研摩法を適用する
場合は、微細孔がセラミツクス表面に露出した状
態となり、薄膜媒体を被着する該基板材としては
不十分であり、また、アルミナ系セラミツク材料
にメカノケミカル研摩法を適用すると、各材質あ
るいは結晶面での化学侵蝕速度が異なるため、微
細孔の露出と同時に結晶段差を生ずる問題があつ
た。 In general, mechanochemical polishing is a surface polishing method that can be applied to magnetic disk substrates, etc.
This mechanochemical polishing method is known as a method for finishing precision surfaces without deteriorating the surface properties of silicon substrates, GGG crystals, ferrite, etc., but when applying this mechanochemical polishing method to ceramic materials that have micropores, The material is exposed on the surface and is not suitable as a substrate material to which a thin film medium is attached.Furthermore, when mechanochemical polishing is applied to alumina-based ceramic materials, the chemical erosion rate differs for each material or crystal plane. Therefore, there was a problem that crystal steps were created at the same time as the micropores were exposed.
発明の目的
この発明は、上述の問題点に鑑み、セラミツク
材料からなる磁気デイスク用基板の欠点を解決
し、すぐれた表面粗度を有し、かつ無孔で無歪み
の表面を有するセラミツクス系磁気デイスク用基
板を目的とし、さらに、かかる無孔・無歪表面の
セラミツクス系磁気デイスク用基板を容易にかつ
安価に得ることができる磁気デイスク用基板の製
造方法を目的としている。Purpose of the Invention In view of the above-mentioned problems, the present invention solves the drawbacks of magnetic disk substrates made of ceramic materials, and provides ceramic-based magnetic disks having excellent surface roughness, non-porous, and non-distorted surfaces. The object of the present invention is to provide a substrate for a magnetic disk, and also to provide a method for manufacturing a magnetic disk substrate that can easily and inexpensively obtain such a ceramic magnetic disk substrate with a non-porous, non-strained surface.
発明の構成
この発明は、磁気デイスク用基板として、要求
される無孔・無歪ですぐれた表面粗度を有するセ
ラミツクス系該基板を目的に種々検討した結果、
アルミナ系セラミツク材料表面に、アルミナをス
パツタし、被着後に特定の条件のメカノケミカル
研摩を施し、すぐれた表面粗度でかつ無孔・無歪
のアルミナスパツタ膜を設けることによつて、前
述した磁気デイスク用基板として要求される条件
を満足したアルミナ系セラミツク磁気デイスク基
板が得られることを知見したものである。Structure of the Invention The present invention was developed as a result of various studies aimed at creating a ceramic substrate with no pores, no distortion, and excellent surface roughness as a substrate for magnetic disks.
By sputtering alumina onto the surface of an alumina-based ceramic material and applying mechanochemical polishing under specific conditions after adhesion, a sputtered alumina film with excellent surface roughness, no pores, and no distortion is provided. It has been discovered that an alumina-based ceramic magnetic disk substrate can be obtained that satisfies the requirements for a magnetic disk substrate.
すなわち、この発明は、
5μｍ以下の微細孔を有し、相対理論密度が90
％以上のアルミナ系セラミツク材料からなる基板
表面に、該基板との熱膨張係数（20℃〜400℃）
差が２×10-6／deg以下、表面粗度（Rz）が100
Å〜180Åでかつ無孔無歪表面を有する0.3μｍ〜
50μｍ膜厚みの純度90％以上、ヌープ硬度600
Kg／mm2〜1500Kg／mm2のアルミナスパツタ膜を有す
ることを特徴とする磁気デイスク用基板であり、
また、
5μｍ以下の微細孔を有し、相対理論密度が90
％以上のアルミナ系セラミツク材料からなる基板
表面に、該基板との熱膨張係数（20℃〜400℃）
差が２×10-6／deg以下の0.5μｍ〜55μｍ膜厚みの
純度90％以上、ヌープ硬度600Kg／mm2〜1500Kg／
mm2のアルミナスパツタ膜を形成した後、該スパツ
タ膜を、粒径1.0μｍ以下のFe2O3、SiO2、MgO、
CeO2またはAl2O3微粉のうち少なくとも１種を、
0.1wt％〜50wt％純水中に懸濁した懸濁液で、
0.05Kg／cm2〜２Kg／cm2の相対的ラツプ荷重で研摩
加工し、表面粗度（Rz）が100Å〜180Åでかつ
無孔無歪表面を有する0.3μｍ〜50μｍ膜厚みの純
度90％以上、ヌープ硬度600Kg／mm2〜1500Kg／mm2
のアルミナスパツタ膜を設けることを特徴とする
磁気デイスク用基板の製造方法である。 That is, this invention has micropores of 5 μm or less and a relative theoretical density of 90
% or more of alumina-based ceramic material, the thermal expansion coefficient (20℃ to 400℃) with the substrate
Difference is 2×10 -6 /deg or less, surface roughness (Rz) is 100
Å~180Å and 0.3μm~ with a non-porous and strain-free surface
50μm film thickness, purity 90% or more, Knoop hardness 600
A magnetic disk substrate characterized by having an alumina spatter film of Kg/mm 2 to 1500 Kg/mm 2 , having micropores of 5 μm or less, and having a relative theoretical density of 90
% or more of alumina-based ceramic material, the thermal expansion coefficient (20℃ to 400℃) with the substrate
Purity of 0.5μm to 55μm with a difference of 2×10 -6 /deg or less, film thickness of 90% or more, Knoop hardness 600Kg/mm 2 to 1500Kg/
After forming an alumina sputtered film with a particle size of 1.0 μm or less , the sputtered film is coated with Fe 2 O 3 , SiO 2 , MgO,
At least one of CeO 2 or Al 2 O 3 fine powder,
0.1wt%~50wt% suspension in pure water,
Polished with a relative lap load of 0.05Kg/ cm2 to 2Kg/ cm2 , with a surface roughness (Rz) of 100Å to 180Å, and a 0.3μm to 50μm film thickness with a surface roughness of 100Å to 180Å and no distortion, and a purity of 90% or more. , Knoop hardness 600Kg/mm 2 ~1500Kg/mm 2
This is a method for manufacturing a magnetic disk substrate, characterized in that a sputtered alumina film is provided.
この発明による磁気デイスク用基板は、研摩後
の基板表面粗度がすぐれているため、0.3μｍ以下
の浮高さにおける磁気ヘツドの安定な浮上と記録
特性の安定性が得られ、また、基板表面に形成さ
れる磁性薄膜の欠陥の要因となる突起や孔状の凹
みがなく、さらに、機械加工、研摩あるいは使用
時の高速・回転に十分耐える機械的強度を有し、
耐食性、耐候性、及び耐熱性にすぐれており、該
基板に要求される条件をすべて満足する。 The magnetic disk substrate according to the present invention has excellent substrate surface roughness after polishing, so stable flying of the magnetic head at a flying height of 0.3 μm or less and stability of recording characteristics can be achieved. It has no protrusions or hole-like depressions that can cause defects in the magnetic thin film that is formed on the surface, and has sufficient mechanical strength to withstand machining, polishing, and high-speed rotation during use.
It has excellent corrosion resistance, weather resistance, and heat resistance, and satisfies all the conditions required for the substrate.
発明の限定条件
この発明において、アルミナ系セラミツク材
は、Al2O3を主成分とし、その他に金属酸化物を
含有するもので、金型成形、押出成形、射出成
形、シート成形等により成型され、焼成処理され
て得られるものである。また、アルミナ系セラミ
ツク材料の微細孔大きさが5μｍを越えると、材
料表面にアルミナスパツタした際に、微細孔部に
気泡が発生して膜精度が劣化するため、微細孔は
5μｍ以下が望ましく、好ましくは3μｍ以下にす
る必要がある。Limitations of the Invention In this invention, the alumina ceramic material has Al 2 O 3 as its main component and also contains metal oxides, and is molded by die molding, extrusion molding, injection molding, sheet molding, etc. , obtained by firing treatment. Additionally, if the micropore size of the alumina-based ceramic material exceeds 5 μm, when alumina is spattered onto the surface of the material, air bubbles will be generated in the micropores and the film accuracy will deteriorate.
The thickness is desirably 5 μm or less, preferably 3 μm or less.
さらに、アルミナ系セラミツク材料の相対理論
密度を90％以上としたのは、上記した微細孔の大
きさが5μｍ以上となりやすいためである。 Furthermore, the reason why the relative theoretical density of the alumina ceramic material is set to 90% or more is because the size of the above-mentioned micropores tends to be 5 μm or more.
アルミナスパツタ膜は、アルミナ基板との熱膨
脹係数の相対差が２×10-6／deg以下で、純度が
90％以上、かつヌープ硬度600Kg／mm2〜1500Kg／
mm2を有することを特徴とする。 The alumina spatter film has a relative difference in coefficient of thermal expansion of 2×10 -6 /deg or less with the alumina substrate, and has a high purity.
90% or more and Knoop hardness 600Kg/mm 2 ~ 1500Kg/
mm 2 .
アルミナスパツタ膜の純度を90％以上としたの
は、アルミナ純度が90％未満であると、スパツタ
時に異常放電現象が起りやすく、また製品品質の
安定性が悪くなるためである。 The reason why the purity of the alumina sputtering film is set to be 90% or more is because if the alumina purity is less than 90%, abnormal discharge phenomenon tends to occur during sputtering, and the stability of the product quality deteriorates.
また、ヌープ硬度600Kg／mm2〜1500Kg／mm2とし
たのは、600Kg／mm2未満では強度が弱く、耐摩耗
性が悪くなり、磁気ヘツドのCSS特性が悪くなり
好ましくなく、また、1500Kg／mm2を越えると硬度
が高くなりすぎ、磁気ヘツドを傷つけるため好ま
しくないためである。 In addition, the Knoop hardness of 600Kg/mm 2 to 1500Kg/mm 2 is undesirable because if it is less than 600Kg/mm 2 the strength will be weak, the wear resistance will be poor, and the CSS characteristics of the magnetic head will deteriorate. This is because if the hardness exceeds mm 2 , the hardness becomes too high and damages the magnetic head, which is undesirable.
アルミナスパツタ膜と前記基板との熱膨張係数
（20℃〜400℃）の差は、大きくなると相互応力が
増し、そりや破壊等の問題が生じるため、両者の
熱膨張係数の相対差が２×10-6／deg以下である
ことが必要であり、また、アルミナスパツタ膜表
面に圧縮応力が掛る方が好ましいため、スパツタ
膜材料の熱膨張係数が、該基板材料の熱膨張係数
より小さいほうが望ましい。また、アルミナスパ
ツタ膜と前記基板との熱膨張係数（20℃〜400℃）
は、同一傾向を有するものが最も好ましい。 As the difference in thermal expansion coefficient (20°C to 400°C) between the alumina spatter film and the substrate increases, mutual stress increases and problems such as warping and breakage occur. ×10 -6 /deg or less, and since it is preferable to apply compressive stress to the surface of the alumina sputtered film, the thermal expansion coefficient of the sputtered film material is smaller than the thermal expansion coefficient of the substrate material. It is more desirable. In addition, the coefficient of thermal expansion between the alumina spatter film and the substrate (20°C to 400°C)
It is most preferable that these have the same tendency.
アルミナスパツタ膜の厚みは、基板と表面に設
ける磁性薄膜との絶縁性を確保するのに必要でか
つ研摩精度を考慮すると0.3μｍ以上の膜厚みが必
要であるが、50μｍを越えると、基板との熱膨張
係数の差によつて生じる応力が、基板内に大きな
歪みをもたらす恐れがあるため、0.3μｍ〜50μｍ
とする。 The thickness of the alumina spatter film is necessary to ensure insulation between the substrate and the magnetic thin film provided on the surface, and in consideration of polishing accuracy, the film thickness must be 0.3 μm or more, but if it exceeds 50 μm, the substrate The stress caused by the difference in thermal expansion coefficient between the
shall be.
また、アルミナスパツタ膜表面粗度を100Å〜
180Åに限定するが、100Å未満では、ヘツド摺動
時に基板のアルミナスパツタ膜との吸着現象によ
り、回転開始時にデイスク盤を傷つける恐れがあ
り、また、180Åを越えるとデイスクの機械的特
性や基板上に形成される薄膜磁性媒体の特性を劣
化させるため好ましくない。 In addition, the surface roughness of the alumina spatter film is 100Å~
The thickness is limited to 180 Å, but if it is less than 100 Å, the disk may be damaged when rotation starts due to adsorption phenomenon with the alumina spatter film on the substrate when the head slides, and if it exceeds 180 Å, the mechanical properties of the disk or the substrate may be damaged. This is not preferable because it deteriorates the characteristics of the thin film magnetic medium formed thereon.
また、アルミナスパツタ膜の研摩加工前の被着
膜厚みを、0.5μｍ〜55μｍとしたのは、スパツタ
法で、均一な膜厚みを得て表面の研摩加工を可能
ならしめるのに必要な膜厚みであり、さらに熱膨
張係数差に起因して基板内に歪が発生するのを防
止するためである。 In addition, the thickness of the alumina sputter film before polishing was set at 0.5 μm to 55 μm because the sputter method was used to obtain a uniform film thickness and to make surface polishing possible. This is to prevent distortion from occurring in the substrate due to the thickness and the difference in thermal expansion coefficient.
アルミナスパツタ膜の研摩加工方法の条件は、
粒径1.0μｍ以下のFe2O3、SiO2、MgO、CeO2ま
たはAl2O3微粉のうち少なくとも１種を、0.1wt
％〜50wt％純水中に懸濁した懸濁液で、0.05Kg／
cm2〜２Kg／cm2の相対的ラツプ荷重で研摩加工する
が、粒径は1.0μｍを越えるとコーテイング膜表面
に疵が発生し、表面粗度が劣化するため好ましく
なく、また、懸濁液の該微粉末含有量が0.1wt％
未満であると研摩効果が少なく、50wt％を越え
ると微粉末による粘性の増加にともない、研摩抵
抗が増加するため、0.1wt％〜50wt％とする。 The conditions for the alumina spatter film polishing method are as follows:
0.1wt of at least one of Fe 2 O 3 , SiO 2 , MgO, CeO 2 or Al 2 O 3 fine powder with a particle size of 1.0 μm or less
%~50wt% suspension in pure water, 0.05Kg/
Polishing is performed with a relative lap load of cm 2 to 2 Kg/cm 2 , but if the particle size exceeds 1.0 μm, it is not preferable because it will cause scratches on the surface of the coating film and deteriorate the surface roughness. The fine powder content is 0.1wt%
If it is less than 50 wt%, the polishing effect will be small, and if it exceeds 50 wt%, the polishing resistance will increase due to the increase in viscosity due to the fine powder.
また、純水には、有機汚濁物や浮遊物を含まな
い水で、イオン交換水や蒸溜水がよく、ラツプ盤
には、Sn、はんだ合金、Pb等の軟質金属あるい
は硬質クロス等が適しており、ラツプ荷重は、
0.05Kg／cm2未満では所要の表面粗度が得られず、
かつ加工能率が悪く、また、２Kg／cm2を越える
と、加工能率の点では望ましいが、研摩精度が劣
化するため、0.05Kg／cm2〜２Kg／cm2の相対的ラツ
プ荷重とする。 In addition, pure water should be water that does not contain organic contaminants or suspended matter, such as ion-exchanged water or distilled water.For lap discs, soft metals such as Sn, solder alloy, Pb, or hard cloth are suitable. The lap load is
If it is less than 0.05Kg/ cm2 , the required surface roughness cannot be obtained.
Moreover, if it exceeds 2 Kg/cm 2 , it is desirable in terms of processing efficiency, but the polishing accuracy deteriorates, so the relative lap load is set at 0.05 Kg/cm 2 to 2 Kg/cm 2 .
好ましい実施態様
この発明におけるアルミナ系セラミツク材料の
組成は、Al2O3、Al2O3−TiC系、Al2O3−TiO2
系、Al2O3−Fe2O3−TiC系等、Al2O3を主成分と
し、そのほかに金属酸化物を含有するアルミナ系
セラミツクス材が好ましく、金型成形、ラバープ
レス、ドクターブレード法等により成形され、さ
らに熱間成形法（HP法）、熱間静水圧プレス法
（HIP）にて焼結処理して得られるものが好まし
い。また、該組成にMgO、NiO、Cr2O3等の公知
の粒成長抑制剤やその他の焼結助剤を含有させる
ことができる。Preferred Embodiment The composition of the alumina ceramic material in this invention is Al 2 O 3 , Al 2 O 3 -TiC system, Al 2 O 3 -TiO 2
Alumina-based ceramic materials containing Al 2 O 3 as a main component and metal oxides in addition, such as Al 2 O 3 -Fe 2 O 3 -TiC series, etc., are preferable, and are suitable for mold forming, rubber press, and doctor blade methods. Preferably, the material is formed by molding by a method such as the above, and then subjected to a sintering treatment by a hot forming method (HP method) or a hot isostatic pressing method (HIP). Furthermore, the composition may contain known grain growth inhibitors such as MgO, NiO, Cr 2 O 3 and other sintering aids.
また、アルミナ系セラミツク基板材の平均結晶
粒径は、5μｍ以下が好ましく、理論密度90％以
上の一般市販規格品を用いることができる。 Further, the average crystal grain size of the alumina ceramic substrate material is preferably 5 μm or less, and a commercially available standard product having a theoretical density of 90% or more can be used.
また、この発明によるアルミナスパツタ膜の厚
みは、用途や使用する材質等に応じて種々選定さ
れるが、膜厚みが0.5μｍ未満では、均一なコーテ
イング膜とすることが困難であり、基板表面の微
細孔を埋めることが困難であり、前述した条件の
メカノケミカル研摩によつて所要の表面粗度及び
無孔化無歪化が得られず、また、55μｍを越える
と、基板との熱膨張係数差により生じる応力によ
つて基板内に大きな歪を発生させる恐れがあるた
め、膜厚みは0.5μｍ〜55μｍとする必要があり、
さらに、膜形成速度の点から、好ましくは15μｍ
〜25μｍ厚みである。 Further, the thickness of the alumina spatter film according to the present invention can be selected depending on the application and the material used, but if the film thickness is less than 0.5 μm, it is difficult to form a uniform coating film, and the substrate surface It is difficult to fill in the fine pores of the substrate, and the required surface roughness, pore-free, and distortion-free surface cannot be obtained by mechanochemical polishing under the conditions described above. The film thickness must be between 0.5 μm and 55 μm, as the stress caused by the difference in coefficients may cause large distortion within the substrate.
Furthermore, from the viewpoint of film formation speed, preferably 15 μm
~25 μm thick.
また、アルミナスパツタ膜のメカノケミカル研
摩後の厚みは、研摩精度を考慮して、0.3μｍ〜
50μｍであり、さらに好ましくは10μｍ〜20μｍで
ある。 In addition, the thickness of the alumina spatter film after mechanochemical polishing is 0.3 μm ~
It is 50 μm, more preferably 10 μm to 20 μm.
発明の効果
この発明による磁気デイスク用基板は、研摩後
の基板表面粗度がすぐれているため、0.3μｍ以下
の浮上高さにおける磁気ヘツドの安定な浮上と記
録特性の安定性が得られ、また、基板表面に形成
される磁性薄膜の欠陥の要因となる突起や孔状の
凹みがなく、さらに、機械加工、研摩あるいは使
用時の高速・回転に十分耐える機械的強度を有
し、耐食性、耐候性、及び耐熱性にすぐれてお
り、該基板に要求される条件のすべてを満足す
る。Effects of the Invention The magnetic disk substrate according to the present invention has excellent substrate surface roughness after polishing, so stable flying of the magnetic head at a flying height of 0.3 μm or less and stability of recording characteristics can be achieved. , there are no protrusions or hole-like depressions that can cause defects in the magnetic thin film formed on the surface of the substrate, and it also has sufficient mechanical strength to withstand machining, polishing, and high-speed rotation during use, and is corrosion resistant and weather resistant. It has excellent hardness and heat resistance, and satisfies all the conditions required for the substrate.
また、この発明によるアルミナ系セラミツク基
板を、両面記録用磁気デイスクに用いる場合は、
該基板両面にアルミナスパツタ膜を形成し、両面
を同時にメカノケミカル研摩加工することによ
り、両面の薄膜中の内部応力は相殺され、平坦度
がすぐれ、かつ表面粗度並びに無孔化無歪化のす
ぐれた基板が得られる。 Furthermore, when the alumina ceramic substrate according to the present invention is used for a double-sided recording magnetic disk,
By forming an alumina spatter film on both sides of the substrate and mechanochemically polishing both sides at the same time, the internal stress in the thin film on both sides is canceled out, resulting in excellent flatness, surface roughness, and no porosity or distortion. An excellent substrate can be obtained.
所定のアルミナスパツタ膜を被着したアルミナ
系セラミツクからなるこの発明による磁気デイス
ク用基板は、研摩加工での形状精度の管理が従来
と比較して容易であり、さらに、基板自体の耐食
性、耐候性に特別配慮する必要がなく、表面の汚
染も、スパツタする際に、スパツタクリーニング
によつて静浄化することができる利点がある。 The magnetic disk substrate according to the present invention, which is made of alumina-based ceramic coated with a predetermined alumina spatter film, is easier to control shape accuracy during polishing than conventional methods, and the substrate itself has excellent corrosion resistance and weather resistance. It is advantageous that there is no need to pay special attention to the properties, and surface contamination can be statically cleaned by spatter cleaning during sputtering.
また、従来のアルミニウム合金のものは、合金
の旋削加工した際に、表面に加工変質層が残存す
るのに対して、この発明によるアルミナ系セラミ
ツク基板は、メカノケミカル研摩仕上げによつ
て、加工変質層が残存せず、表面にはバルクでの
応力歪が生じることがなく、基板に被着される磁
性薄膜への歪みの転写が生じない利点がある。 In addition, while conventional aluminum alloy substrates leave a damaged layer on the surface when the alloy is turned, the alumina-based ceramic substrate of the present invention has a mechanochemical polishing finish. There is an advantage that no layer remains, no bulk stress strain occurs on the surface, and no strain is transferred to the magnetic thin film deposited on the substrate.
すなわち、基板表面にアルミナスパツタ膜を設
けるため、薄膜結晶がアルモフアスの均一構造と
なつており、従来の多結晶アルミナ系セラミツク
をメカノケミカル研摩した際の微細孔の露出ある
いは結晶段差が発生しない。 That is, since the alumina sputtered film is provided on the substrate surface, the thin film crystal has an aluminous, uniform structure, and the exposure of micropores or crystal steps that occur when conventional polycrystalline alumina ceramics are mechanochemically polished are not generated.
上述したように、この発明の磁気デイスク用基
板を用いることにより、信頼性が著しく向上した
高密度磁気デイスク記録媒体を製作することがで
き、また、出発アルミナ系セラミツク材料に理論
密度90％以上の規格品が使用でき、量産性にすぐ
れている。 As mentioned above, by using the magnetic disk substrate of the present invention, it is possible to produce a high-density magnetic disk recording medium with significantly improved reliability. Standard products can be used and mass production is excellent.
実施例
実施例 １
基板には、組成がAl2O399.95％で、圧縮成形
後、焼結し、5μｍ以下の微細孔を有し、平均結
晶粒径が4.0μｍ有し、相対理論密度が97％で、熱
膨張係数が77×10-7／deg、寸法95mmφ×１mm厚
みのアルミナ系セラミツク基板を用いた。Examples Example 1 The substrate has a composition of 99.95% Al 2 O 3 , is sintered after compression molding, has micropores of 5 μm or less, has an average crystal grain size of 4.0 μm, and has a relative theoretical density of An alumina ceramic substrate with a thermal expansion coefficient of 97% and a thermal expansion coefficient of 77×10 -7 /deg and dimensions of 95 mmφ×1 mm thickness was used.
つぎに、上記アルミナ系セラミツク基板の表面
を精密ラツプ法により表面粗度（Rz）200Å以下
に精密研摩した。 Next, the surface of the alumina-based ceramic substrate was precisely polished to a surface roughness (Rz) of 200 Å or less by a precision lapping method.
基板と同一材質のアルミナからなる寸法直径
350mm×厚み６mmのターゲツト板を用い、高周波
スパツタ装置により、スパツタアルゴン圧１×
10-5mmbarに到達排気後に、基板表面の線状の
ため、スパツタクリーニングより、表面層を500
Å程度除去し、スパツタリングした。 Diameter made of alumina, the same material as the substrate
Using a target plate of 350 mm x 6 mm thickness, a sputtering argon pressure of 1 x was applied using a high frequency sputtering device.
After evacuation reached 10 -5 mmbar, the surface layer was cleaned by 500 mm due to the linearity of the substrate surface.
Approximately 1.5 Å was removed and sputtered.
正スパツタの投入パワーは5kWであり、基板
側に負のバイアス（−100V）を印加した。バイ
アス効果により、セラミツクボア部のステツプカ
バレージが図られ、ボア部にもアルミナが付着し
た。また、スパツタ膜面の表面粗度は500Åであ
つた。 The input power of the positive sputter was 5kW, and a negative bias (-100V) was applied to the substrate side. Due to the bias effect, step coverage of the ceramic bore was achieved, and alumina also adhered to the bore. The surface roughness of the sputtered film was 500 Å.
なお、従来の酸化物のスパツタ法では、スパツ
タ速度が遅く、被着に時間を要したが、電極間距
離を40mmとして投入パワーを大きくしたことによ
り、スパツタレートは500Å／minで、、20μｍ厚
み形成するのに400分を要した。 In addition, in the conventional oxide sputtering method, the sputtering speed was slow and it took time to deposit, but by setting the distance between the electrodes to 40 mm and increasing the input power, the sputtering rate was 500 Å/min, and a thickness of 20 μm was formed. It took 400 minutes to complete.
次に、該コーテイング膜を、粒径0.5μｍの
CeO2微粉末を、純水中に20wt％懸濁した懸濁液
で、ラツプ盤にSn盤を用い、0.5Kg／cm2の相対的
ラツプ荷重で研摩加工し、表面粗度（Rz）を160
Åに仕げた。この際の研摩代は3μｍで平坦度は
1μｍであつた。 Next, the coating film was coated with a particle size of 0.5 μm.
A suspension of 20 wt% of CeO 2 fine powder in pure water was polished using an Sn disc as a lapping disc with a relative lapping load of 0.5 kg/cm 2 to determine the surface roughness (Rz). 160
I served Å. The polishing allowance at this time is 3μm, and the flatness is
It was 1 μm.
接触針径0.1μｍＲの薄膜段差測定器
（Talystep）により、上記の研摩後のコーテイン
グ膜の表面状況を測定し、その結果を第１図Ａに
示す。また、同様に、コーテイング前の基板の表
面状況を測定し、その結果を第１図Ｂに示す。 The surface condition of the coating film after polishing was measured using a thin film step measuring device (Talystep) with a contact needle diameter of 0.1 μmR, and the results are shown in FIG. 1A. Similarly, the surface condition of the substrate before coating was measured, and the results are shown in FIG. 1B.
第１図より、アルミナ系セラミツク基板表面の
微細孔は、コーテイング膜の研摩により表面の無
孔化が得られており、表面粗度160Åに仕上げら
れたことが明らかである。 From FIG. 1, it is clear that the fine pores on the surface of the alumina-based ceramic substrate were made non-porous by polishing the coating film, and the surface was finished with a surface roughness of 160 Å.
また、アルミナスパツタ膜と基板との付着力を
判定する方法として、硬度計を用い、打重を50ｇ
から1000ｇまで順次増大させて、コーテイング膜
の剥離の有無を判定基準として測定したところ、
1000ｇまで剥離はなく、強固な付着力を示した。 In addition, as a method to judge the adhesion force between the alumina spatter film and the substrate, we used a hardness meter and set the casting weight to 50 g.
The weight was gradually increased from 1000g to 1000g, and the determination was made based on the presence or absence of peeling of the coating film.
There was no peeling up to 1000g, showing strong adhesion.
この発明によるアルミナセラミツク基板は、第
１図の如く、基板表面が無孔化、無歪化されたこ
とにより、従来の基板の微細孔に基因した素子の
歩留低下を防止し、無孔化された基板表面に形成
される被着磁性膜の特性及び信頼性の向上に寄与
することが明らかである。 As shown in Fig. 1, the alumina ceramic substrate according to the present invention has a non-porous and non-strained substrate surface, which prevents the reduction in device yield caused by the fine pores of conventional substrates. It is clear that this contributes to improving the characteristics and reliability of the magnetic film formed on the surface of the substrate.
第１図Ａ図とＢ図は、実施例において、薄膜段
差測定器（Talystep）により、基板表面に被着
して研摩後のコーテイング膜の表面状況と、コー
テイング前の基板の表面状況を示すグラフであ
る。
Figures A and B are graphs showing the surface condition of the coating film deposited on the substrate surface after polishing and the surface condition of the substrate before coating, which were measured using a thin film step measuring device (Talystep) in the example. It is.
Claims (1)
90％以上のアルミナ系セラミツク材料からなる基
板表面に、該基板との熱膨張係数差が２×10-6／
deg以下、表面粗度（Rz）が100Å〜180Åでかつ
無孔無歪表面を有する0.3μｍ〜50μｍ膜厚みの純
度90％以上、ヌープ硬度600Kg／mm2〜1500Kg／mm2
のアルミナスパツタ膜を有することを特徴とする
磁気デイスク用基板。 ２ 5μｍ以下の微細孔を有し、相対理論密度が
90％以上のアルミナ系セラミツク材料からなる基
板表面に、該基板との熱膨張係数差が２×10-6／
deg以下の0.5μｍ〜55μｍ膜厚みの純度90％以上、
ヌープ硬度600Kg／mm2〜1500Kg／mm2のアルミナス
パツタ膜を形成した後、該スパツタ膜を、粒径
1.0μｍ以下のFe2O3、SiO2、MgO、CeO2または
Al2O3微粉のうち少なくとも１種を、0.1wt％〜
50wt％純水中に懸濁した懸濁液で、0.05Kg／cm2〜
２Kg／cm2の相対的ラツプ荷重で研摩加工し、表面
粗度（Rz）が100Å〜180Åでかつ無孔無歪表面
を有する0.3μｍ〜50μｍ膜厚みの純度90％以上、
ヌープ硬度600Kg／mm2〜1500Kg／mm2のアルミナス
パツタ膜を設けることを特徴とする磁気デイスク
用基板の製造方法。[Claims] 1. Having micropores of 5 μm or less, and having a relative theoretical density of
The surface of the substrate made of 90% or more alumina-based ceramic material has a thermal expansion coefficient difference of 2×10 -6 /
degree or less, surface roughness (Rz) of 100 Å to 180 Å, 0.3 μm to 50 μm film thickness, purity of 90% or more, and Knoop hardness of 600 Kg/mm 2 to 1500 Kg/mm 2
A magnetic disk substrate characterized by having an alumina spattered film. 2. Has micropores of 5 μm or less, and has a relative theoretical density of
The surface of the substrate made of 90% or more alumina-based ceramic material has a thermal expansion coefficient difference of 2×10 -6 /
Purity of 90% or more with a film thickness of 0.5 μm to 55 μm below deg,
After forming an alumina sputtered film with a Knoop hardness of 600Kg/mm 2 to 1500Kg/mm 2 , the sputtered film was
Fe 2 O 3 , SiO 2 , MgO, CeO 2 or less than 1.0μm
At least one type of Al 2 O 3 fine powder, 0.1 wt% ~
0.05Kg/cm 2 - 50wt% suspension in pure water
Polished with a relative lap load of 2Kg/ cm2 , with a surface roughness (Rz) of 100Å to 180Å and a non-porous and undistorted surface, with a film thickness of 0.3μm to 50μm, purity of 90% or more,
A method for manufacturing a magnetic disk substrate, characterized by providing an alumina spattered film having a Knoop hardness of 600Kg/mm 2 to 1500Kg/mm 2 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20679185A JPS6266419A (en) | 1985-09-18 | 1985-09-18 | Substrate for magnetic disk and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20679185A JPS6266419A (en) | 1985-09-18 | 1985-09-18 | Substrate for magnetic disk and its production |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6266419A JPS6266419A (en) | 1987-03-25 |
| JPH0352128B2 true JPH0352128B2 (en) | 1991-08-09 |
Family
ID=16529152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20679185A Granted JPS6266419A (en) | 1985-09-18 | 1985-09-18 | Substrate for magnetic disk and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6266419A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02154309A (en) * | 1988-12-07 | 1990-06-13 | Tdk Corp | Production of substrate for thin-film magnetic head |
| JPH0577287U (en) * | 1992-03-26 | 1993-10-22 | 浩一 松岡 | Storage device for socks knitted fabric |
| JP2515842Y2 (en) * | 1992-08-07 | 1996-10-30 | 浩一 松岡 | Sock knitted fabric container |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4838107A (en) * | 1971-09-13 | 1973-06-05 | ||
| JPS60138730A (en) * | 1983-12-27 | 1985-07-23 | Kyocera Corp | Substrate for magnetic disc |
-
1985
- 1985-09-18 JP JP20679185A patent/JPS6266419A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4838107A (en) * | 1971-09-13 | 1973-06-05 | ||
| JPS60138730A (en) * | 1983-12-27 | 1985-07-23 | Kyocera Corp | Substrate for magnetic disc |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6266419A (en) | 1987-03-25 |
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