JPH0450650B2 - - Google Patents
Info
- Publication number
- JPH0450650B2 JPH0450650B2 JP16133183A JP16133183A JPH0450650B2 JP H0450650 B2 JPH0450650 B2 JP H0450650B2 JP 16133183 A JP16133183 A JP 16133183A JP 16133183 A JP16133183 A JP 16133183A JP H0450650 B2 JPH0450650 B2 JP H0450650B2
- Authority
- JP
- Japan
- Prior art keywords
- support
- ions
- film
- coercive force
- magnetic recording
- 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
Links
- 150000002500 ions Chemical class 0.000 claims description 24
- 230000005291 magnetic effect Effects 0.000 claims description 21
- 238000007733 ion plating Methods 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 4
- 239000000956 alloy Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000010408 film Substances 0.000 description 26
- 230000015572 biosynthetic process Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 230000005415 magnetization Effects 0.000 description 6
- 239000010409 thin film Substances 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- -1 polyethylene terephthalate Polymers 0.000 description 4
- 229920000139 polyethylene terephthalate Polymers 0.000 description 4
- 239000005020 polyethylene terephthalate Substances 0.000 description 4
- 101700004678 SLIT3 Proteins 0.000 description 3
- 102100027339 Slit homolog 3 protein Human genes 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000010884 ion-beam technique Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000005566 electron beam evaporation Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910002058 ternary alloy Inorganic materials 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 229910020630 Co Ni Inorganic materials 0.000 description 1
- 229910000684 Cobalt-chrome Inorganic materials 0.000 description 1
- 229910002440 Co–Ni Inorganic materials 0.000 description 1
- 229910020517 Co—Ti Inorganic materials 0.000 description 1
- 229910020515 Co—W Inorganic materials 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000010952 cobalt-chrome Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Landscapes
- Manufacturing Of Magnetic Record Carriers (AREA)
Description
産業上の利用分野
本発明はCo系合金から成る薄膜を磁気記録層
とする磁気記録媒体の製造方法に関する。
従来例の構成とその問題点
磁気記録に於て高密度化を図るために媒体に要
求されるは薄い磁気記録層で大きい抗磁力を有す
るものであることは良く知られていることであ
る。
この要求に生産規模でこたえていくことは必ず
しも容易ではない。
特に媒体の表面と直交する方向の磁化を利用す
るいわゆる垂直磁化記録に用いる媒体の磁気記録
層を高速で得てしかも大きい抗磁力に制御するの
は容易ではない。
現状で大きい抗磁力を確実に制御できるのはグ
ロー放電によつて生じた陽イオンをCo−Cr合金
等のターゲツトに射突させ、ターゲツトよりCo，
Cr原子を叩き出して所定の支持体に付着せしめ
るいわゆるスパツタリング法であるが、前記した
メカニズムより予測できるよう膜形成速度は高々
10Å／secと極めて遅い。
一方真空蒸着法では支持体の温度を200℃以上
の高温にすることが初めて垂直方向の抗磁力が
1KO¨eを越える条件が現れるが、用いられる支持
体の耐熱性に制約があるのと蒸着時の支持体の温
度を精度良く、例えば±５℃に制御するのは難か
しく長尺の支持体上に連続して一定の特性の垂直
磁化膜を得るのは困難である。
しかしながらこの方法は膜形成速度としては
200Å／sec〜2000Å／secと大きくとれるのでこ
の方法の改良として支持体温度を下げるためにイ
オンプレーテイング法が鋭意検討されている。
イオンプレーテイング法は、支持体上に形成さ
れた膜と支持体との付着力が大きくなる、支持体
の温度を100℃以下でも大きい抗磁力が得られる
傾向をもつ等の利点はあるが例えば1000〔O¨e〕の
抗磁力を得る場合膜形成速度は第１図に示したよ
うに、グロー放電のパワーに依存する。
グロー放電のパラーを大きくしていくと膜形成
速度は途中まで大きくできるが、パワーを大きく
していても逆に抗磁力が下がつてしまう現象があ
ることがわかる。
第１図の結果は、厚さが20μｍのポリエチレン
テレフタレートを直径50cmの回転ドラムに沿つて
移動させ、ドラム直下25cmに配した電子ビーム蒸
発源より蒸発させたCo−Crをドラム２cm離れた
位置にポリエチレンテレフタレートの移動方向に
開孔部として2.5cmのスリツトを有する遮へい板
を配してイオンプレーテイングした場合である。
グロー放電は、２ターンの高周波コイルを遮へ
い板から５cmと16cmの間に配して、前記コイルに
13.56MHzの高周波電力を投入するようにして発
生させた。放電ガスはArを用い、真空度は4.2×
10-4TORRの場合でありCrの含有量は18重量％
で、Co−Crの膜厚は0.2μｍ一定とした。
従来のイオンプレーテイング法による改良は第
１図にみられるように限界がある。
この現象は、グロー放電パワーを大きくすると
イオンボンバードによる逆の作用効果である、結
晶に欠陥を発生させる作用が支配的になつてきて
かえつて結晶配向性が悪くなることによるもので
大きい抗磁力を得るには支持体温度をあげざるを
得ないことになり改良できる範囲は想像以上に狭
いものであつた。
発明の目的
本発明は、高速で高抗磁力のCo系合金から成
る磁気記録層を得る磁気記録媒体の製造方法を提
供するものである。
発明の構成
本発明は支持体の表面にイオンプレーテイング
法によつてCo系合金から成る磁気記録層を形成
する際に、Coに添加する元素のイオンの運動エ
ネルギーがCoのイオンの運動エネルギーより大
きいことを特徴とするものである。
Co及びCoに添加する元素のうちイオンが占め
る割合は高々10％程度である。
勿論100％イオンで構成することもできるが当
然膜形成速度はスパツタリング法と同程度であ
り、前記した程度即ち10％程度のイオンを有効に
利用するのが本発明の特徴的な作用効果をもたら
すポイントである。
即ちイオンをCoとCoに添加する元素の両者が
同一のエネルギーで構成された従来例と異なり、
Coに添加する元素の方の運動エネルギーを大き
くすることでCoより添加元素の易動度が大きく
なり結晶の表面にまで移動し易くなり、結果とし
て粒子間の磁気的相互作用を弱めることが抗磁力
が大きくなるものと推察できる。
この作用効果を明確に得るには、支持体の温度
にも依存するが、Coのイオンの運動エネルギー
の1.2倍以上から高々３倍の範囲に設定するのが
好ましい。
一方エネルギーからみると高々2KeVにおさえ
ることが好ましい。
これ以上になるとむしろ結晶配向性が悪化し、
抗磁力の分散が大きくなり、磁気記録媒体として
用いた時の記録感度が下がる欠点が生じるからで
ある。
従つてエネルギーの選択はCoイオンを基礎に
しての倍率と、絶対値の両者で前記条件の範囲内
で行われるものである。
実施例の説明
以下本発明の実施例を図面を参照しながら説明
する。
第２図は、本発明の実施例を説明するために用
いた蒸着装置の基本構成を示すものである。
支持体１は、図示していない巻取装置により巻
取られる過程で図示していない冷却装置で冷却さ
れながら遮へい板２の開孔部スリツト３を通過し
た蒸気流により磁気記録層となる強磁性金属薄膜
４の形成作用を受ける。
蒸発源５はCo用とCoに添加する元素（これを
Ｍと呼ぶ）の両者を隣接してスリツト３直下に配
置する。Co６とＭ７は夫々所定の蒸発温度に制
御され矢印で模式的に示したよにCo蒸気流８、
Ｍ蒸気流９として支持体１の一部に向う。
Co蒸気流８、Ｍ蒸気流９には例えば加熱源が
加速された電子ビームの時は一部イオンが含まれ
る。
ここでは、この両者のイオンは１％以下にして
且つ積極的には加速しないようにした。
イオン発生源は別々に配し、Coイオン源１０
より放出されたイオンは所定の運動エネルギーを
付与しCoイオンビーム１１とし偏向磁界１２で
偏向して、Co蒸気流８のうち支持体１にスリツ
ト３を通過して向うものと同じ方向に加速した。
同様にＭイオンビーム１４もＭイオン源１３よ
り偏向磁界１５で偏向して支持体１に向わせた。
実施例 １
10.5μｍポリエチレンテレフタレートフイルム
を支持体として用い５℃の媒体を表面近くに循環
させた２重円筒構造の直径50cmの円筒キヤンに沿
つて前記支持体を6.9ｍ／minで移動させた。
スリツト開孔部の支持体移動方向の幅は4.6cm
で、蒸発源は偏向型の電子ビーム蒸発源を一対用
いた。イオン源はマグネトロン放電型式の金属イ
オン源を用いた。
イオンは偏向磁界（ポールピースの直径は10
cm）を調整してCo+，M+イオンのみを用いるよ
うにした。
第３図はCoと、ＭとしてCrを選んでイオンの
割合をCo，Cr全体に占める割合を夫々８％とし
て、Co+のエネルギーを500eV、1000eVの２水準
選び、Co+に対してM+のエネルギーを変えて、
薄膜形成速度を約5000Å／sec一定として0.2μｍ
のCoCr膜の垂直抗磁力を示したものである。（但
しCrは18重量％である）
第１図と比較しても明らかなように5000Å／
secという高速で1000〔O¨e〕以上の大きい抗磁力
をもつた垂直磁化膜が得られる利点がある。
又、支持体は冷却していても垂直磁化膜が得ら
れ磁気テープ用として最も諸特性が優れたポリエ
チレンテレフタレートフイルムを支持体に選ぶこ
とができる点も利点である。
実施例 ２
実施例１の同じ装置条件でCo−Moの垂直磁化
膜の試作を行つた。
Co−Mo（Mo：20.5重量％）0.16μｍを約4000
〔Å／sec〕の膜形成速度で得た。
夫々のイオンの割合を５％と10％の２水準を選
びCo+を600eV一定としMo+イオンのエネルギー
を1000eV、1500eV、2000eVの３条件設定して得
たものの垂直抗磁力は次表のようであつた。
INDUSTRIAL APPLICATION FIELD The present invention relates to a method of manufacturing a magnetic recording medium using a thin film made of a Co-based alloy as a magnetic recording layer. Conventional Structure and Problems It is well known that in order to achieve high density magnetic recording, a medium is required to have a thin magnetic recording layer and a large coercive force. Meeting this demand on a production scale is not necessarily easy. In particular, it is not easy to obtain a magnetic recording layer of a medium used for so-called perpendicular magnetization recording, which utilizes magnetization in a direction perpendicular to the surface of the medium, at high speed and to control it to a large coercive force. Currently, a large coercive force can be reliably controlled by bombarding a target such as a Co-Cr alloy with cations generated by glow discharge.
This is the so-called sputtering method, in which Cr atoms are ejected and attached to a predetermined support, but as expected from the mechanism described above, the film formation rate is very high.
Extremely slow at 10 Å/sec. On the other hand, in the vacuum evaporation method, the vertical coercive force is achieved for the first time when the temperature of the support is raised to a high temperature of 200℃ or higher.
Conditions exceeding 1KO¨e appear, but there are restrictions on the heat resistance of the support used, and it is difficult to precisely control the temperature of the support during vapor deposition, for example to ±5°C, and long supports are difficult to control. It is difficult to obtain a continuous perpendicular magnetization film with constant characteristics. However, this method has a low film formation rate.
The ion plating method is being intensively studied as an improvement to this method in order to lower the support temperature, since it can achieve a high rate of 200 Å/sec to 2000 Å/sec. The ion plating method has advantages such as increased adhesion between the film formed on the support and the support, and a tendency to obtain a large coercive force even when the temperature of the support is below 100°C. When obtaining a coercive force of 1000 [O¨e], the film formation rate depends on the power of the glow discharge, as shown in FIG. It can be seen that although the film formation rate can be increased to some extent by increasing the glow discharge polarity, there is a phenomenon in which the coercive force decreases even if the power is increased. The results shown in Figure 1 show that polyethylene terephthalate with a thickness of 20 μm is moved along a rotating drum with a diameter of 50 cm, and Co-Cr evaporated from an electron beam evaporation source placed 25 cm directly below the drum is placed 2 cm away from the drum. This is a case in which ion plating was performed by arranging a shielding plate with a 2.5 cm slit as an opening in the direction of movement of polyethylene terephthalate. Glow discharge is performed by placing a two-turn high-frequency coil between 5 cm and 16 cm from the shielding plate, and
It was generated by inputting 13.56MHz high frequency power. Ar is used as the discharge gas, and the degree of vacuum is 4.2×
In the case of 10 -4 TORR, the Cr content is 18% by weight.
The Co-Cr film thickness was kept constant at 0.2 μm. Improvements made by conventional ion plating methods have limitations, as seen in FIG. This phenomenon is due to the fact that when the glow discharge power is increased, the opposite effect of ion bombardment, which is the effect of generating defects in the crystal, becomes dominant and the crystal orientation worsens, resulting in a large coercive force. In order to obtain this, the temperature of the support had to be raised, and the range of improvement was narrower than expected. OBJECTS OF THE INVENTION The present invention provides a method for manufacturing a magnetic recording medium that produces a magnetic recording layer made of a Co-based alloy with high coercive force at high speed. Structure of the Invention The present invention provides a method in which, when forming a magnetic recording layer made of a Co-based alloy on the surface of a support by an ion plating method, the kinetic energy of the ions of an element added to Co is greater than the kinetic energy of the Co ions. It is characterized by its large size. The ratio of ions to Co and the elements added to Co is about 10% at most. Of course, it is also possible to make the film composed of 100% ions, but the film formation rate is of course comparable to that of the sputtering method, and the characteristic effects of the present invention are brought about by effectively utilizing the ions described above, that is, about 10%. That's the point. In other words, unlike the conventional example in which both the ion and the element added to Co have the same energy,
By increasing the kinetic energy of the element added to Co, the added element has a higher mobility than Co, making it easier to move to the surface of the crystal, and as a result weakening the magnetic interaction between particles. It can be inferred that the magnetic force increases. In order to clearly obtain this effect, it is preferable to set the kinetic energy to a range of 1.2 times or more to at most 3 times the kinetic energy of Co ions, although it also depends on the temperature of the support. On the other hand, from the point of view of energy, it is preferable to keep it to at most 2 KeV. If it exceeds this, the crystal orientation will actually worsen,
This is because the dispersion of coercive force becomes large, resulting in a disadvantage that recording sensitivity decreases when used as a magnetic recording medium. Therefore, the energy selection is made within the range of the above conditions both in terms of magnification based on Co ions and in absolute value. DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows the basic configuration of a vapor deposition apparatus used to explain an embodiment of the present invention. The support 1 is made of ferromagnetic material that becomes a magnetic recording layer by a vapor flow that passes through the opening slit 3 of the shielding plate 2 while being cooled by a cooling device (not shown) during the process of being wound up by a winding device (not shown). Under the action of forming the metal thin film 4. The evaporation source 5 is arranged immediately below the slit 3 for both Co and an element added to Co (this is called M) adjacent to each other. Co6 and M7 are each controlled to a predetermined evaporation temperature, and as shown schematically by arrows, Co vapor flow 8,
M vapor stream 9 is directed towards a part of the support 1. The Co vapor flow 8 and the M vapor flow 9 contain some ions, for example, when the heating source is an accelerated electron beam. Here, both ions were kept at 1% or less and not actively accelerated. The ion sources are arranged separately, and the Co ion source 10
The emitted ions are given a predetermined kinetic energy and turned into a Co ion beam 11, which is deflected by a deflecting magnetic field 12, and accelerated in the same direction as the Co vapor flow 8 that passes through the slit 3 toward the support 1. . Similarly, the M ion beam 14 was also deflected by the deflection magnetic field 15 from the M ion source 13 and directed toward the support 1 . Example 1 A 10.5 μm polyethylene terephthalate film was used as a support and the support was moved at 6.9 m/min along a cylindrical can with a diameter of 50 cm and a double cylinder structure in which a medium at 5° C. was circulated near the surface. The width of the slit opening in the direction of movement of the support is 4.6cm.
A pair of deflected electron beam evaporation sources were used as the evaporation sources. A magnetron discharge type metal ion source was used as the ion source. The ions are deflected by a magnetic field (the diameter of the pole piece is 10
cm) was adjusted to use only Co + and M + ions. Figure 3 shows Co and Cr selected as M, the proportion of ions in the total Co and Cr being respectively 8%, two energy levels of Co + of 500eV and 1000eV selected, and M + with respect to Co + . change the energy of
0.2 μm with a constant thin film formation rate of approximately 5000 Å/sec
This figure shows the perpendicular coercive force of the CoCr film. (However, Cr is 18% by weight) As is clear from the comparison with Figure 1, 5000Å/
It has the advantage that a perpendicularly magnetized film with a large coercive force of 1000 [O¨e] or more can be obtained at a high speed of sec. Another advantage is that a perpendicularly magnetized film can be obtained even when the support is cooled, and polyethylene terephthalate film, which has the best properties for magnetic tapes, can be selected as the support. Example 2 A Co--Mo perpendicularly magnetized film was experimentally produced using the same equipment conditions as in Example 1. Co-Mo (Mo: 20.5% by weight) 0.16μm approximately 4000
The film was formed at a film formation rate of [Å/sec]. The perpendicular coercive force obtained by selecting two levels of the proportion of each ion, 5% and 10%, and setting Co + at a constant 600 eV and setting the energy of Mo + ions at 1000 eV, 1500 eV, and 2000 eV is as shown in the table below. It was hot.
【表】
比較例として第１図の結果を得た装置で約4000
Å／secで得たCo−Mo膜は605〔O¨e〕が最大の抗
磁力であつた。
尚、本発明は、垂直磁化膜に限らず、面内磁化
膜に於ても大きい抗磁力を得ることのできるもの
でありCo−Cr，Co−Moに限らず、Co−Ti，Co
−Si，Co−Ni，Co−Ru，Co−Ｗ、等のCo系二
元合金、Co−Cr−Mo，Co−Ni−Cr，Co−Cr−
Rh等の三元合金であつても効果は同じである。
なお三元合金の場合はCoの磁性を一番希釈す
る元素のイオンエネルギーをCO+のエネルギーよ
り大きくするようにして実施するものとする。
発明の効果
以上のように本発明によれば支持体温度を2000
℃以上の高温にしなくても、極めて大きい膜形成
速度で大きく抗磁力の垂直磁化膜が得られる。
従つて耐熱性の高い特殊なフイルムを用いなく
ても垂直磁化膜を有する金属薄膜型磁気記録媒体
が容易に高い生産性でできるため、磁気デイスク
のみに用途は留らず磁気テープとしても短波長記
録の要請にこたえることができる[Table] As a comparative example, approximately 4000
The Co-Mo film obtained at Å/sec had the maximum coercive force of 605 [O¨e]. The present invention is applicable not only to perpendicular magnetization films but also to in-plane magnetization films, and is applicable not only to Co-Cr and Co-Mo but also to Co-Ti and Co.
-Co-based binary alloys such as Si, Co-Ni, Co-Ru, Co-W, Co-Cr-Mo, Co-Ni-Cr, Co-Cr-
The effect is the same even with ternary alloys such as Rh. In the case of a ternary alloy, the ion energy of the element that dilutes the magnetism of Co the most is set to be greater than the energy of CO + . Effects of the Invention As described above, according to the present invention, the support temperature can be increased to 2000.
A perpendicularly magnetized film with a large coercive force can be obtained at an extremely high film formation rate without raising the temperature to a temperature higher than °C. Therefore, metal thin film magnetic recording media with perpendicular magnetization films can be easily produced with high productivity without the use of special films with high heat resistance, so their use is not limited to magnetic disks, but also as magnetic tapes with short wavelengths. Able to respond to requests for records
第１図は従来のイオンプレーテイング法によつ
て得られた垂直磁化膜の特性図、第２図は本発明
を実施するために用いたイオンプレーテイング装
置の基本構成を示す図、第３図は本発明により得
られる垂直磁化膜の特性図である。
１……支持体、２……遮へい板、３……スリツ
ト、４……強磁性金属薄膜、５……蒸発源、１
０，１３……イオン源、１１，１４……イオンビ
ーム。
Fig. 1 is a characteristic diagram of a perpendicularly magnetized film obtained by the conventional ion plating method, Fig. 2 is a diagram showing the basic configuration of the ion plating apparatus used to carry out the present invention, and Fig. 3 1 is a characteristic diagram of a perpendicularly magnetized film obtained according to the present invention. DESCRIPTION OF SYMBOLS 1... Support, 2... Shielding plate, 3... Slit, 4... Ferromagnetic metal thin film, 5... Evaporation source, 1
0,13...Ion source, 11,14...Ion beam.
Claims (1)
つてCo系合金から成る磁気記録層を形成する際
に、Coに添加する元素のイオンの運動エネルギ
ーがCoのイオンの運動エネルギーより大きくす
ることを特徴とする磁気記録媒体の製造方法。1. When forming a magnetic recording layer made of a Co-based alloy on the surface of a support by the ion plating method, the kinetic energy of the ions of the element added to Co is made larger than the kinetic energy of the Co ions. A method for manufacturing a magnetic recording medium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16133183A JPS6052931A (en) | 1983-09-01 | 1983-09-01 | Production of magnetic recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16133183A JPS6052931A (en) | 1983-09-01 | 1983-09-01 | Production of magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6052931A JPS6052931A (en) | 1985-03-26 |
| JPH0450650B2 true JPH0450650B2 (en) | 1992-08-14 |
Family
ID=15733049
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16133183A Granted JPS6052931A (en) | 1983-09-01 | 1983-09-01 | Production of magnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6052931A (en) |
-
1983
- 1983-09-01 JP JP16133183A patent/JPS6052931A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6052931A (en) | 1985-03-26 |
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