JPH02104681A - Production of core for magnetic head - Google Patents

Abstract

PURPOSE:To produce a core for a magnetic head having high reliability by irradiating a gap bar with laser light while specifying the power, beam diameter and scanning velocity when grooves regulating a track width are formed in the gap bar with laser. CONSTITUTION:A chamber 1 is evacuated and halide-contg. gas is introduced through a nozzle 2 to fill the chamber 1 with an atmosphere under 10-200Torr pressure. A gap bar 11 on a sampling holder 3 is irradiated with laser light 7 through a quartz window 5 and an X-Y table 4 is moved to form plural grooves 15 regulating a track width 14 in the bar 11. At this time, the bar 11 is irradiated with the laser light 7 under the conditions of 0.05-3.3 W laser power P, <=50mum beam diameter D and 2-250mum/sec scanning velocity V satisfying an inequality V <=-25+21/(P<3>/D+0.08) and the grooves 15 are formed by etching caused by laser. About <=+ or -2mum dimensional accuracy is attained and a small track width 14 having high accuracy is obtd.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a core for a magnetic head, and in particular a method for manufacturing a core for a magnetic head of a track using laser-induced etching in which a thermochemical reaction is induced by a laser. It's about how to do it.

(Prior art) In recent years, the magnetic recording density of floppy disk drives (PDD), fixed magnetic disk drives (RDD), VTRs, etc. has been steadily increasing, and as a result, the track width of magnetic heads has become narrower and more precise. There is a tendency to Currently, the dimensional accuracy of track width is ±2 μm or less for VTRs and PODs, and R
DD requires ±1tIr@ or less.

When forming the cores for these magnetic heads, it has been known that the track portions are processed by laser processing in the air. Disclosed. .

(Problem to be solved by the invention) However, in these methods, the processing temperature of the workpiece reaches higher than the melting point temperature of the workpiece, so processing distortion due to heat and accompanying cranking occur on the processing surface, and the magnetic head This resulted in deterioration of the characteristics of the In addition, there are problems such as thermal distortion and cracks, as well as adhesion of molten solidified matter and molten debris from the workpiece to the machined surface and its surrounding areas, resulting in a decrease in surface roughness and dimensional accuracy, which has become a requirement in recent years. There was a problem in that high-precision track machining with a high dimensional accuracy of ±2 μm or less could not be performed.

This invention was made in order to solve the above-mentioned conventional problems, and its purpose is to manufacture highly reliable magnetic head cores by processing highly accurate tracks using a laser-induced etching method. The purpose is to provide a method.

(Means for Solving the Problems) A method for manufacturing a core for a magnetic head according to the present invention is a manufacturing method in which the track width of the core for a magnetic head is defined by laser processing, in an atmosphere containing a halogen or a halogen compound at 10 to 200 Torr. So, 0.05~3.3W
When the scanning speed V is in the range of 2 to 250 p m/sec, the rape light has a power P of 50 μm or less and a beam diameter of 50 μm or less.
This method is characterized by irradiation at a scanning speed that satisfies the following relational expression and processing by laser-induced etching.

(Function) In the above-described configuration, a gap bar having a coil winding hole and a magnetic gap is irradiated with a predetermined laser beam at a predetermined scanning speed onto the gap bar surface in an atmosphere of halogen or a halogen compound. , a thermochemical reaction occurs between the gap bar and the gas component, and the reaction product evaporates and scatters, thereby progressing laser-induced etching.

As a result, if grooves or holes are processed by the laser-induced etching of the present invention to form tracks, problems such as processing distortion, deterioration, cracks, etc. due to melting and solidification of the workpiece in conventional laser processing due to heat can be solved. Can be done.

In one aspect of the present invention, the magnetic helad core is produced by forming grooves or holes to define the track width in a gap bar made of ferrite or the like by laser-induced etching.
After forming the track, the process of embedding glass into the groove or hole to reinforce the track as necessary, the depth of the magnetic gap from the sliding surface of the magnetic head with the recording medium to the coil winding hole. That is, it is obtained through post-processing such as polishing the sliding surface until the depth reaches the required dimension, and further slicing the core to the required width.

Depth is approximately 30μ steel for VTR, FDD, RDD
It is about 5 μm. Therefore, when forming a track on this gap bar, the depth of the groove or hole used to define the track must be at least 10 am, taking into consideration post-processing such as polishing the sliding surface. Yes, preferably 30 μm or more, more preferably 50 μm
m or more is required. Further, the dimensional accuracy for defining the track needs to be ±2 μI or less, preferably ±1 μm or less.

In the method of the present invention, processing depth and dimensional accuracy are discussed in relation to laser power and laser beam scanning speed. According to experimental results, the machining depth tends to increase as the laser power increases and the scanning speed decreases. However, if the laser power becomes too large, the amount of melting due to the heat of the laser beam will be greater than the amount of chemical reaction caused by the reaction gas, which will cause adhesion of molten solids and cracks on the machined surface, reducing dimensional accuracy. do. Furthermore, if the scanning speed becomes too high, a sufficient chemical reaction cannot occur, and the same tendency occurs.

Therefore, if the laser power is less than 0.05 W, the power is insufficient to cause laser-induced etching, and the required depth of 10 μI or more cannot be obtained. Furthermore, in order to be able to implement this laser-induced etching industrially, it is desirable that it can be processed in 30 seconds or less per track compared to conventional machining, and the scanning speed is low (both require 2 μya/sec or more). .

Even if the laser power and scanning speed are constant, if the convergence diameter of the laser beam changes, the dimensional accuracy and processing depth will also change. If the convergence diameter of the laser beam is 50μ or less, the required processing depth and dimensional accuracy can be obtained.
Since the convergence diameter of the laser beam affects the processed shape, it is also necessary to consider the convergence diameter of the laser beam when selecting processing conditions. When reducing the laser beam diameter, it is preferable to lower the laser power in order to prevent the amount of melting due to the heat of the laser beam from becoming larger than the amount of chemical reaction caused by the reaction gas. In this case, the laser power is preferably high in order to sufficiently cause laser-induced etching.

The conditions for machining tracks with a dimensional accuracy of ±2μ or less and a machining depth of 10μ or more at an industrially practical machining speed are the laser beam diameter, which is a limiting condition in the claims of the present invention. is 50 pm or less, laser power P is 0.05~3.3 匈, scanning speed ■ is 2~25
In the range of 0μs/sec, and the relational expression ■≦-2
5+21/(P'/D+0.08) (see FIG. 2, which will be described later).

In this laser-induced etching method, the atmospheric gas is preferably a substance that produces a substance that stably evaporates into the atmosphere through a thermochemical reaction with the workpiece. Iron, the main component of ferrite, forms a compound with a halogen element that has a relatively high vapor pressure.

Therefore, gas containing halogen or halogen compound gas is suitable as the atmospheric gas, and among them, CC1g
is preferred because it is stable and has relatively low toxicity, making it easy to handle.

If the gas pressure is too low, a sufficient chemical reaction will not occur, and the machined surface will appear to be processed only by heat, similar to conventional laser processing.If the gas pressure is too high, the ferrite and gas will It becomes difficult to volatilize chemical reaction products,
Reaction products adhere to the machined surface and its surroundings, reducing dimensional accuracy. Therefore, it is desirable to set the gas pressure of the gas containing halogen or halogen compound to 10 to 200 Torr, more preferably 40 to 100 Torr.
It is desirable to set it to r.

Various lasers can be used as a laser light source, but ferrite has a high absorption rate for wavelengths of 1 μm or less, so A, ion laser, and WAG laser have excellent oscillation stability and a small spread angle of laser light. It is desirable to use a laser light source such as a second harmonic.

(Example) (1) Apparatus configuration FIG. 1 shows an example of an apparatus for implementing the present invention. The chamber 1 placed on the x-y table 4 is directly connected to the vacuum pump 8 via the valve 9, and
The nozzle 2 that opens into the chamber 1 is a valve 10.
is connected to at least one type of gas source containing halogen or a halogen compound. Furthermore,
A quartz window 5 is provided on the upper surface of the chamber 1, and a laser beam 7 from a laser light source 6 disposed above the quartz window 5 passes through the quartz window 5 to the chamber 1.
It is designed to be irradiated internally.

Inside the chamber 1, a gapper 11 to be etched is placed on a sampling holder 3. In the processing procedure, first, the vacuum pump 8 is operated to evacuate the chamber 1, and then the valve 10 is opened to fill the chamber 1 with gas at a predetermined pressure. Next, by moving the XY table 4 while irradiating the laser beam 7 onto the gapper 11, processing into a desired shape can be performed.

(2) Determination of processing conditions A case in which the present invention is applied using the above-mentioned apparatus will be described below.

FIG. 2 is a graph showing the range of conditions for performing processing with a dimensional accuracy of ±2μ or less. In this range, the laser beam diameter is 50μ or less and the laser power P is 0.05.
~3.3 H, the scanning speed V is in the range of 2 to 250 μm8ec, and the upper limit of the scanning speed is the upper limit of the dimensional accuracy when the laser power and beam diameter are constant. It can be understood that the range is limited by 25+21/(P''/D+0.08).

From FIG. 2, for example, when the laser beam diameter is 2.2μ steel and the laser power is 0.2-, P3/D is 0.
004, and a dimensional accuracy of ±2μ or less can be obtained within the scanning speed range of 2 to 226 g s/see. At a laser power of 0.5-, P'/D is 0.057, which is ±2 μm within the scanning speed range of 2 to 128 μm/sec.
The following dimensional accuracy can be obtained. laser power 1
-, P3/D is 0.455 and scanning speed 2 to 14
Dimensional accuracy of ±2 μm or less can be obtained within the range of μm/sec.

Next, when the laser beam diameter is 4.5 μm, P”/D is 0.002 at a laser power of 0.2-, and a dimensional accuracy of ±2 μm or less can be obtained within the scanning speed range of 2 to 232 μm/see. is possible.Laser power 0.5
For W, P3/D is 0.028 and the scanning speed is 2 to 1.
Dimensional accuracy of ±2 μm or less can be obtained within the range of 70 μm/sec. At laser power 1-, P″/D
is 0.222, and a dimensional accuracy of ±2 μm or less can be obtained within the scanning speed range of 2 to 45 μn+/sec.

Next, when the laser beam diameter is 10.7 μm, P″l/D is 0.012 at a laser power of 0.5−, which is ±2 μm within the scanning speed range of 2 to 203 μm/sec.
The following dimensional accuracy can be obtained. laser power 1
P'/D is 0.093 and the scanning speed is 2-96.
Dimensional accuracy of ±2 μm or less can be obtained within the range of μm/see. At laser power 1.5-, P'/D
is 0.315, and the scanning speed is 2 to 28 um/se.
A dimensional accuracy of ±2 μm or less can be obtained within the range of c.

Next, when the laser beam diameter is 20 am, P3/D is 0.006 at a laser power of 0.5-, and a dimensional accuracy of ±2 μm or less can be obtained within a scanning speed range of 2 to 219 μm/sec. At laser power 1-, P'/D is 0.05 and scanning speed is 2-137 μm7
Dimensional accuracy of ±2 μm or less can be obtained within the range of sec. At a laser power of 1.5W, P3/D is 0.
169, and a dimensional accuracy of ±2 μm or less can be obtained within the scanning speed range of 2 to 60 pm/sec.

At a laser power of 2, P'/D is 0.4, and a dimensional accuracy of ±2 μm or less can be obtained within a scanning speed range of 2 to 19 μm and 7 seconds.

Further, when the laser beam diameter is 50 μm, P3/D is 0.003 at a laser power of 0.5-, and a dimensional accuracy of ±2 μm or less can be obtained within a scanning speed range of 2 to 228 μm and 17 seconds. Laser power 11I
For I, P3/D is 0.02 and the scanning speed is 2 to 185.
Dimensional accuracy of ±2 μm or less can be obtained within the range of μm/sec. At a laser power of 2 mm, P'I10 becomes 0.16, and a dimensional accuracy of ±2 μm or less can be obtained within a scanning speed range of 2 to 63 μm/sec.

At a laser power of 3 W, p2/mouth becomes 0.54, and a dimensional accuracy of ±2 μm or less can be obtained within a scanning speed range of 2 to 9 μIll/sec.

As mentioned above, it can be seen that even when the laser power and scanning speed are constant, the dimensional accuracy changes as the laser beam diameter changes. Furthermore, the machining depth also differs. Therefore, appropriate machining conditions should be selected by comprehensively determining laser power, scanning speed, and laser beam diameter, taking into account the desired dimensional accuracy and machining depth.

FIG. 3 is a graph showing the results of an experiment conducted using a laser beam diameter of 2.2 μm. The solid line is the upper limit of dimensional accuracy of ±2 μm, and the broken line is the upper limit of machining depth of 10 μm. For example, when the laser power is 0.2 W, and the scanning speed is 2 to 154 μH/sec, processing is performed with dimensional accuracy of ±2 μm or less. Although a depth of 10 uw1 or more can be obtained, at a scanning speed of 154 to 246 μm/sec, a dimensional accuracy of ±2 μm or less can be obtained, but a machining depth of 10 μm or more cannot be obtained. It can be seen that when the scanning speed is 246 μm/sec or more, it is not possible to obtain a dimensional accuracy of ±2 μm or less. When the laser beam diameter is 2.2 μm, the range of processing conditions for machining depth LOata or more and dimensional accuracy of ±2 μm or less is laser power 0.05 to 1.15 W, scanning speed 2 to 22
0 μm736c.

FIG. 4 is a graph showing the results of an experiment conducted using a laser beam diameter of 4.5 μm. The solid line is the upper limit of the dimensional accuracy of ±2 μm, and the broken line is the upper limit of the machining depth of 108 m. For example, when the laser power is 0.3 W, a machining depth of 10 μm or more can be obtained with a dimensional accuracy of ±2 μm or less at a scanning speed of 2 to 210 μl II/sec, but a machining depth of 10 μm or more can be obtained at a scanning speed of 210 to 232 μm/sec. ±2μ
Although it is possible to obtain a machining depth of 10 μm or less, it is not possible to obtain a machining depth of 10 μm or more.

Dimensional accuracy ±2μ at scanning speeds of 232μm/sec or higher
It can be seen that even less than m cannot be obtained. When the laser beam diameter is 4.5 μm, the processing conditions for machining depth of 10 μm or more and dimensional accuracy of ±2 μm or less are: laser power of 0.08 to 1.48 W, scanning speed of 2 to 226 μm.
m/sec.

FIG. 5 is a graph showing the results of an experiment with a laser beam diameter of 1007 μm. Solid line indicates dimensional accuracy ±2μm
The broken line is the upper limit of the processing depth of 10 μm.

For example, when the laser power is 0.3 W, a machining depth of 10 μm or more can be obtained with a dimensional accuracy of ±2 μm or less at a scanning speed of 2 to 200 μm/sec, but a machining depth of 10 μm or more can be obtained at a scanning speed of 200 to 258 μm/sec. Accuracy ±2μ
It is possible to obtain a machining depth of 10.m or less. czm or more cannot be obtained.

At scanning speeds of 258μm/sec or higher, dimensional accuracy is ±2μ
It can be seen that even less than m cannot be obtained. When the laser beam diameter is 10.7μm, the processing depth is 10μm or more,
The range of processing conditions for dimensional accuracy of ±2 μm or less is laser power 0.1 to 1.96 L scanning speed 2 to 145 μ@/s
It is ec.

FIG. 6 is a graph showing the results of an experiment conducted using a laser beam diameter of 20 μm. The solid line is the upper limit of the dimensional accuracy of ±2 μm, and the broken line is the upper limit of the processing depth of 10 μm. For example, if the laser power is 0.6-, the scanning speed is 2
At ~190 μra/sec, it is possible to obtain a machining depth of 10 μm or more with a dimensional accuracy of ±2 μm or less, but at a scanning speed of 1
At 90 to 206 μm/sec, a dimensional accuracy of ±2 μm or less can be obtained, but a machining depth of 10 am or more cannot be obtained.

Dimensional accuracy ±2μm at scanning speed of 206μm7sec or higher
It can be seen that it cannot be less than ±2μ steel or less than ±2μ.

When the laser beam diameter is 20 μm, the processing conditions for machining depth of 108 m or more and dimensional accuracy of ±2 μm or less are laser power of 0.2 to 2.4 W, scanning speed of 2 to 200
um/sec.

FIG. 7 is a graph showing the results of an experiment with a laser beam diameter of 50 μm. The solid line is the upper limit of the dimensional accuracy of ±2 μm, and the broken line is the upper limit of the processing depth of 10 μm. For example, if the laser power is 1-, the scanning speed is 2-
At 145μ@/sec, it is possible to obtain a machining depth of 10μ or more with a dimensional accuracy of ±2μm or less, but at a scanning speed of 14μ
At 5 to 185 μm/sec, a dimensional accuracy of ±2 μm or less can be obtained, but a machining depth of 10 μm or more cannot be obtained. Dimensional accuracy ±2μ at scanning speeds of 185μm/sec or higher
It can be seen that even less than m cannot be obtained. When the laser beam diameter is 50 μm, the processing conditions for machining depth of 108 m or more and 2 μm or less for dimensional accuracy are laser power 0.45 to 3.25 W, scanning speed 2 to 172 μn/
sec.

As mentioned above, it can be seen that if the laser beam diameter changes, the condition range of laser power and scanning speed to obtain the required dimensional accuracy and processing depth changes. The guidelines for determining the machining conditions are: To increase the machining depth, (1) increase the laser power, (2) decrease the scanning speed, and (3) decrease the laser beam diameter.

To increase dimensional accuracy, (1) lower the laser power, (2) lower the scanning speed. Furthermore, in order to increase the aspect ratio (processing depth/processing width) of the processed groove, the diameter of the laser beam may be reduced. As mentioned above, appropriate machining conditions can be determined by comprehensively determining laser power, scanning speed, laser beam diameter, and gas pressure, taking into account machining depth, dimensional accuracy, machining shape, etc. is necessary.

(2) Preparation of magnetic helad core FIGS. 8(a) to 8(d) are perspective views showing the manufacturing process of a core for a VTR magnetic head according to the present invention.

First, as shown in FIG. 8(a), a ferrite rod 12a
and a ferrite bar 12b having a coil winding hole 13 are bonded together by glass bonding, solid phase reaction bonding, or the like to form a gapper 1 having a magnetic gap 12.
form 1. Next, the laser power was 0.5-1, the scanning speed was 10 μ++/sec, and the laser beam diameter was 4.5 pI.
The prepared gapper 11 was installed in the apparatus shown in FIG. 1 under the condition of I%CCl4 gas pressure of 60 Torr, and the track width 14 was set on the gapper 11 as shown in FIG. 8(b).
A plurality of grooves 15 are machined. Next, Figure 8 (
As shown in c), glass 16 is embedded in the processed groove 15 and polished to a predetermined size. Finally, this was cut into a predetermined width to obtain a core 17 for a VTR head as shown in FIG. 8(d). The magnetic head core 17 thus obtained had highly accurate tracks formed with no adhesion of cranks or molten matter, and had high reliability.

It should be noted that the present invention is not limited to the method of manufacturing cores for VTR heads, but can also be suitably used for cores for various magnetic heads such as ROD and FDD.

Furthermore, the present invention is not limited to track machining, but can also be suitably used for various types of machining of ferrite materials, such as coil winding hole machining and air bearing surface machining of cores for RDD magnetic heads. Furthermore, it is suitably used for processing cores for composite magnetic heads made of magnetic alloys such as sendust and permalloy and ferrite.

(Effects of the Invention) As described above, according to the manufacturing method of the present invention, by irradiating search light with a predetermined relationship of laser beam diameter, laser power, and scanning speed in a predetermined atmosphere, gap There is no adhesion of molten solidified matter or molten spatter to the bar, there is no deterioration due to heat, there is no processing distortion, and there is no cranking associated with it, and narrow, high-precision tracks can be formed, making it possible to create a highly reliable core for magnetic heads. can be manufactured.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing an example of an apparatus for carrying out this invention. Figure 2 is a graph showing the range of conditions for processing with dimensional accuracy of ±2 μm or less. Figure 3 is an experiment using a laser beam diameter of 2.2 μm. Figure 4 is a graph showing the results of experiments conducted with a laser beam diameter of 4.5 μm. Figure 5 is a graph showing the results of experiments conducted with a laser beam diameter of 10.7 μm. The figure is a graph showing the results of experiments conducted with a laser beam diameter of 20 μm, Figure 7 is a graph showing the results of experiments conducted with a laser beam diameter of 50 μm, and Figures 8 (a) to (d) are graphs showing the results of experiments conducted with a laser beam diameter of 20 μm.
FIG. 2 is a perspective view showing a processing procedure when applied to manufacturing a core for a t-air head. 1... Chamber 2... Nozzle 3... Sampling holder 4... X-Y table 5... Quartz window 6... Laser light source 7... Laser light 8... Vacuum pump 9, 10... Valve 11... Gap par 12... Magnetic gap 12a, 12b... Ferrite bar material 13... Coil winding hole 14... Track width 1
5...Groove 16...Glass 17...
・Core 2nd figure φ (11/p'lR) 3rd figure Ol 2 3shifu-/zu7-
p(vr) Fig. 4 Laser l shear (Wn Fig. 5 Laser °-bar') - (W'') Fig. 6 θ/2
3 Laser puff (W-n Figure 7 Laser/f7-(w) Flash ρ Procedural amendment April 3, 1989 Director General of the Patent Office Yoshi 1) Moon Yi Lord 3. Relationship with the case of the person making the amendment Patent Applicant 6, Contents of the Amendment (as shown in the attached sheet) 1. Delete "±2 μm" on page 16, line 10 of the specification. 2. Correct "crack" in the first line of page 19 to "crack". 3. On page 19, line 17 of the same page, correct "saser light" to "laser light." 4. Correct "7...laser light" in the fourth line of page 21 to "7kawa laser light." 5. Change “8...vacuum pump” on page 21, line 5 of the same page to “8.
...Vacuum pump," he corrected.

Claims (1)

[Claims] 1. In a manufacturing method in which the track width of a magnetic head core is defined by laser processing, 0.0
It has a power P of 5 to 3.3 W and a beam diameter D of 50 μm.
The scanning speed V of the laser beam is 2 to 250 μm/
In the range of sec, V≦-25+21/(P^3/D+0.
A method for manufacturing a core for a magnetic head, characterized in that the core is irradiated at a scanning speed that satisfies the relational expression 08) and processed by laser-induced etching.