JPS6042531B2 - Electrode formation method for recycled needles - Google Patents

Description

[Detailed Description of the Invention] Reproduction on a recording trace in an information recording medium disk (disc) having a recording trace formed by arranging bits corresponding to an information signal in a spiral or concentric form. By sliding the reproduction needle of the element (pickup) into sliding contact and detecting the change in capacitance value that occurs according to the state of the information signal in the recorded trace as a change in the amount of electricity, the information recorded at high density on the disk can be detected. In the so-called capacitance change detection type information recording and reproducing method that reproduces the signal, the information signal in the recorded trace on the disk is read by detecting the change in capacitance value using an electrode provided on the reproduction needle. Since this is done by detecting In addition to having the feature that it can be made smaller to improve resolution and thus enable recording and reproduction of information signals even at a low rotational speed of the disk, it has many other advantages, so its practical use has been greatly improved. research is being promoted.

By the way, a disc on which information signals are recorded at high density has a small recording trace interval (track pitch) and a significantly short recording wavelength on the disc surface, so the information signal from the disc is The playback stylus of the playback element used for reading out data has a minute shape at the tip, and since the disk rotates at a high rotational speed, the playback stylus used in sliding contact with the disk is is the time until it becomes unusable due to wear (lifetime)
becomes significantly shorter. The applicant company has been conducting continuous research in order to provide regenerated needles that can obtain good regeneration results even after long-term use, and has so far submitted patent applications, for example. Japanese Patent Application No. 1983-137216, Japanese Patent Application No. 1982-20065, Japanese Patent Application No. 1983-22764,
Research results have been revealed in other areas.

Now, FIG. 1d is a perspective view of a representative example of the above-mentioned already proposed regenerated needle, and FIGS. 1a to 1c are regenerated needles having the configuration shown in FIG. It is a figure which shows the manufacturing process of a needle.

Next, with reference to FIGS. 1A to 1D, the manufacturing process of the regenerated needle having the configuration shown in FIG. 1D, and the locations of problems will be briefly explained as follows.

Figure 1a shows a thin rod A made of a wear-resistant, high-hardness material (for example, sapphire) that is the raw material for a regenerated needle, and the surface Aa of the thin rod A described above is formed by adhering the electrode material of the regenerated needle. This is the aspect that should be taken care of.

A thin film B of an electrode material is deposited on the surface Aa of the thin sapphire rod A, as shown in FIG. 1B.

The thin rod with the thin film B of the electrode material adhered to the surface M as shown in FIG. an electrode part 4 which is polished over the surface M so that the apex angle is θ on the surface M;
The inclined surfaces 6 and 7 are formed symmetrically with respect to the center line 5 of the surface Aa.

Next, as shown in FIG. 1d, inclined surfaces 8 and 9 are formed symmetrically with respect to the center line 5 of surface Aa by polishing, so that the sliding surface 10 becomes 5 as shown in FIG. 1d. A rectangular recycled needle is completed.

The regenerated needle manufactured according to the manufacturing method explained with reference to FIGS.
Since the shape of is formed simultaneously with the formation of the inclined surfaces 6 and 7 by polishing, it is impossible to prevent the width of the electrode end appearing on the sliding contact surface 10 from changing due to wear of the recycled needle. In the regenerated needle shown in FIG. 1d, the width of the electrode portion 4 gradually increases as the regenerated needle wears, and the cross stroke increases as the regenerated needle wears, resulting in deterioration of regeneration characteristics. It is.

In order to keep the width of the electrode that appears on the sliding contact surface constant even when the regenerated needle is worn out, the sloped surfaces 6 and 7 are designed so that an electrode part of a constant width is formed near the tip of the electrode part 4. However, as the recording density of information signals on disks has become more sophisticated, the electrode width of the electrode section 4 of the playback needle has become smaller, for example, around 0.8 μm. If the electrodes are of a certain size, it is very difficult to form the slopes 6 and 7 by polishing as described above, and at the same time process them so that electrodes of a constant width are formed. It is difficult to suit.

In addition, in the manufacturing method of the regenerated needle shown in FIG. 1, in order to obtain a predetermined electrode width and to ensure that the length and width of the sliding contact surface are respectively predetermined sizes,
Since it is necessary to control the amount of polishing on the inclined surfaces 6 to 9, the manufacturing method of the recycled needle shown in FIG. 1 has the disadvantage of extremely poor productivity.

Furthermore, in the regenerated needle shown in FIG. 1d, the electrode portion 4 is formed at the same time as the sloped surface is formed by polishing the thin sapphire rod as described above, but the sapphire and the electrode material are different. There is an extremely large difference in hardness and coefficient of thermal expansion between the two, and because the electrode width is narrow and the adhesion area is small, chipping and peeling at the edges of the electrode part, and drips on the sides of the electrode part may occur. may occur.

The present invention provides a regenerated needle that satisfactorily solves the various problems encountered when manufacturing regenerated needles using the conventional method described above, and that makes it possible to easily obtain a regenerated needle equipped with an electrode having a predetermined shape and size. This invention has been made in order to provide a method for forming electrodes, and the method for forming electrodes on regenerated needles of the present invention will be specifically explained in detail below with reference to the accompanying drawings.

FIG. 2a is a perspective view of a regenerated needle body S made of a high-hardness material having wear resistance, and a conductive layer is preliminarily applied to at least a portion of the surface of the regenerated needle body S, including a portion where an electrode is formed. CR is formed.

The thickness of the conductive layer CR to be formed on the regenerated needle body S described above corresponds to the thickness of the electrode in the completed regenerated needle, and the constituent material of the regenerated needle body S is In the case of sapphire, the conductive layer CR
is a conductive adhesion layer CR formed by adhering a conductive substance to the back surface of the regenerated needle body by applying means such as vapor deposition, sputtering, ion blating, etc.;
When the constituent material of is diamond, the above-mentioned conductive layer CR may be used as a conductive adhesion layer, as in the case where the constituent material of the regenerated needle body S is sapphire.
The conductive layer CR may be formed by forming a conductive layer on the surface of diamond with carbon, which is a constituent element of diamond itself.

Conductive adhesive layer C to be formed on the surface of the recycled needle body S
R is a conductor such that when it is irradiated with energy rays such as laser light, X-rays, electron beams, gamma rays, heat rays, etc., the irradiated part becomes a high-resistance material as described below. For example, when a layer of hafnium, aluminum, copper, tin, etc. is used as the conductive adhesion layer, an energy beam is applied in an oxygen or air atmosphere as described below. When the irradiation of
The portion irradiated with the energy beam changes into an oxide due to heating and becomes a highly resistive material. In addition, if the constituent material of the regenerated needle body S is diamond and a conductive layer CR is formed on its surface, if the layer is irradiated with an energy beam in an oxygen or air atmosphere, , the part irradiated with the energy beam becomes a high-resistance material.

A supplementary explanation on this point is as follows.
First, conductive layer C is applied to the surface of the diamond regenerated needle body.
To form R, it is sufficient to treat the regenerated diamond needle body at high temperature in a vacuum containing a trace amount of oxygen or in an inert gas containing a trace amount of oxygen. Diamond recycled needle body 10-
Heating to 1200℃ in a vacuum of 5T0rr, then lowering the temperature to 1100℃ and reducing the degree of vacuum to 6×1
0-3T0rr', in this state for 30 minutes, 2 hours,
The conductive layer formed by graphitizing the surface of the regenerated needle body when subjected to high temperature treatment for different retention times of 4 hours and 9 hours, respectively, has a retention time of 3C.
If the holding time is between ＠, the sheet resistance is 20KΩ, if the holding time is 2 hours, the sheet resistance is BOΩ, and if the holding time is 4 hours, the sheet resistance is 600Ω. It will be done. Next, when the regenerated needle body on which the conductive layer exhibiting low sheet resistance is formed on the surface as described above is subjected to high temperature treatment in an oxygen atmosphere (same as in air), the conductive layer having the low sheet resistance described above is treated. changes into a high-resistance layer exhibiting high sheet resistance.

According to the experimental results, when a regenerated needle body having a conductive layer with a sheet resistance of 500 Ω is held in an oxygen atmosphere or air at temperatures of 280°C, 400°C, and 550°C for 4 hours, the temperature decreases. When the temperature is 280℃, the sheet resistance changes from the initial 500Ω to 600Ω, and when the temperature is 400℃, the sheet resistance changes from the initial 500Ω to 600Ω.
Ω? It has been found that the sheet resistance changes from the initial 500Ω to 1 when the temperature is 550°C. The method for forming electrodes of a recycled needle of the present invention involves forming a conductive layer CR or a conductive adhesive layer CR on the surface of a recycled needle body made of a highly hard material having wear resistance.
A laser beam is applied to a part other than the part of the predetermined electrode shape,
It is made by irradiating it with energy rays such as X-rays, electron beams, gamma rays, heat rays, etc. to make it a high-resistance material, and to give the function of an electrode to a part of a predetermined electrode shape, as shown in Figure 2b. 2 is a perspective view of a regenerated needle in which electrodes have been formed according to the above-described electrode formation method for regenerated needles, and the portions shown with hunting in FIG.・Indicates a high-resistance part. In order to make a portion of the conductive layer CR or conductive adhesion layer CR formed on the surface of the regenerated needle body other than the portion of the predetermined electrode shape into a high-resistance material, irradiating the portion with an energy beam is as follows: A conductive layer CR or a conductive adhesion layer formed on the surface of a reproducing needle body by deflecting an energy beam used for making the conductive layer CR or conductive adhesion layer CR high in resistance using a deflection device. The energy beam is irradiated onto the regenerating needle body so as to show a scanning pattern corresponding to a portion other than the portion of the predetermined electrode shape in CR, or the energy beam generated by the energy beam source is made to correspond to the predetermined electrode pattern. The conductive layer CR or the conductive adhesion layer CR in the regenerated needle body may be irradiated through a mask pattern.

The conductive layer CR formed on the surface of the regenerated needle main body S is irradiated with an energy beam, or the conductive adhesion layer CR formed on the surface of the regenerated needle main body S is made of a metal film, such as a thin film of hafnium, aluminum, copper, tin, etc. In such a case, the conductive adhesion layer CR is irradiated with energy rays in an oxygen atmosphere (or in the air), thereby reducing the irradiation of the energy rays on the conductive layer CR or the conductive adhesion layer CR. The exposed portion can be made into a high-resistance material.

According to the experimental results, the specific resistance of the electrode portion formed on the conductive layer CR or conductive adhesion layer CR formed on the surface of the regenerated needle body S and the other portions made of high resistance material is If the ratio differs by more than 1:100, it is clear that the electrode portion formed in the conductive layer CR or the conductive adhesion layer CR in a predetermined pattern functions well as the electrode of the regenerated needle. has been done.

Note that the processing of the recycled needle body S into a desired shape may be carried out before or after the process of forming a conductive layer or conductive adhesive layer on the recycled needle body S, or before or after the process of irradiating the conductive layer or the conductive adhesive layer with energy beams, etc. However, processing on the recycled needle body is
It is desirable that this be performed before the energy beam irradiation step.

As is clear from the detailed explanation above, the method for forming electrodes of regenerated needles according to the present invention is suitable for forming electrodes on parts other than the predetermined electrode shape in the conductive layer or conductive adhesive layer formed on the surface of the regenerated needle main body S. It is extremely simple to make a part of a predetermined electrode shape function as an electrode by irradiating the part with energy rays such as laser beams, X-rays, electron beams, gamma rays, heat rays, etc. to make it a high-resistance material. By carrying out the method of the present invention, it is possible to easily produce a regenerated needle with a desired electrode pattern. It will be resolved.

[Brief explanation of drawings]

Figures 1A to 1D are perspective views for explaining the manufacturing process of a recycled needle according to the conventional method, and Figures 2A and 2B are perspective views of the recycled needle body for explaining the method for forming electrodes of the recycled needle according to the present invention. FIG. S: Recycled needle body, CR: Conductive layer or conductive adhesive layer.

Claims (1)

[Claims] 1. A conductive layer or a conductive adhesive layer formed on the surface of a regenerated needle body made of a high-hardness material with wear resistance, in which a portion other than the predetermined electrode shape is irradiated with an energy beam to make it a high-resistance material. , a method for forming electrodes on recycled needles in which a portion of a predetermined electrode shape has an electrode function