JPH02276009A - Production of core for magnetic head - Google Patents

Abstract

PURPOSE:To shorten working time while maintaining high working accuracy by finding out the specific conditions and scanning speed of a laser beam at the time of a laser induced etching in an aq. soln. of an alkaline metal hydroxide. CONSTITUTION:A ferrite bar 51a and a ferrite bar material 51b having a groove 52 corresponding to a coil winding hole are joined to obtain a gap bar 53. The working to regulate the track width of gaps 54-1, 54-1 is then executed by the laser induced etching in an atmosphere contg. a halogen or halide of prescribed conditions. The point exclusive of the point to regulate the track width is then irradiated with the laser beam having 50 to 1300mW power P and <=20mum diameter at the scanning speed V in a 2 to 150mum/sec range and the scanning speed to simultaneously hold equations I+II in the aq. soln. of the alkaline metal hydroxide having 5 to 55wt.% concn. and is thus worked by the laser induced etching, by which the groove 55 is formed. The working time is shortened while high working accuracy is maintained.

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 more particularly to 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 is about the method.

(Prior Art) In recent years, the magnetic recording density of floppy disk drives (FDD), 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. The current dimensional accuracy of track width is VTR.

FDD requires ±2 μm or less, and RDD requires ±1 μm 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, as disclosed in Japanese Patent Laid-Open No. 5129118, Japanese Patent Laid-open No. 57-212617, etc. ing.

However, in these methods, the processing temperature of the workpiece reaches a temperature higher than the melting point temperature of the workpiece, resulting in heat-induced processing distortion and accompanying cracks on the processed surface, leading to deterioration of the characteristics of the magnetic head. 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.

In order to improve this point of accuracy, the present applicant has proposed
-45387 discloses that a highly accurate track width can be obtained by processing the portion of a magnetic head core that defines the track width by laser-induced etching in an atmosphere containing a predetermined halogen or halide. . Furthermore, in order to increase the overall speed, it is also disclosed that it is advantageous to perform laser-induced etching on areas other than those that define the track width in an acid such as phosphoric acid or an alkali such as potassium hydroxide. .

(Problems to be Solved by the Invention) However, the technique disclosed in Japanese Patent Application Laid-open No. 63-45387 mentioned above, in particular, performs laser-induced etching in an atmosphere containing halogen etc. for the portion defining the track width, and For example, laser etching in an acid or alkaline etching solution for areas other than the specified areas can shorten the overall processing time and obtain a highly accurate track width. Because the conditions for laser-induced etching were insufficient, there was a problem in that it was not possible to perform optimal and precise processing.

The purpose of the present invention is to solve the above-mentioned problems, improve the technology described in Japanese Patent Application Laid-Open No. 63-45387 by the applicant, and manufacture a core for a magnetic head that can achieve high processing accuracy and shorten processing time. It is intended to provide a method.

(Means for Solving the Problems) A first aspect of the method for manufacturing a magnetic head core of the present invention is to form a magnetic head core by laser processing, in which a portion defining a track width is treated with halogen or a halide. In an aqueous solution of alkali metal hydroxide with a concentration of 5 to 55 wt%, the parts other than those that define the track width are etched by laser-induced etching in an atmosphere containing The laser beam has a scanning speed of 2 to 150 μm.
/see, the relational expression of ■≦0.34P+13 and ■≦
It is characterized in that it is irradiated at a scanning speed that simultaneously satisfies the relational expression -0.17P+217, and is processed by laser-induced etching.

Further, a second invention of the method for manufacturing a magnetic head core of the present invention is a manufacturing method in which a magnetic head core is formed by laser processing, in which a portion defining a track width is laser-induced etched in an atmosphere containing halogen or a halide. The parts other than those that define the track width were treated with a phosphoric acid aqueous solution with a concentration of 10 to 9 wt%.
A laser beam with a diameter of 50 μm or less with a power P of 900 mW was scanned at a scanning speed V of 2 to 200 p m /
In the range of sec, the relational expression of VS2.31 P+34 and V≦
It is characterized in that it is irradiated at a scanning speed that simultaneously satisfies the relational expressions -0, 14P + 271, and is processed by laser-induced etching.

(Function) In the above-described configuration, the portions that define the track width are processed by laser-induced etching in an atmosphere containing halogen or halides, and the portions other than those that define the track width are etched in an aqueous solution of alkali metal hydroxide. Or, in a method for manufacturing a core for a magnetic head in which processing is performed by laser-induced etching in aqueous phosphoric acid solution = 6, the optimum laser beam conditions and scanning speed for laser-induced etching in each aqueous solution have been found. It has become possible to shorten machining time while maintaining high machining accuracy.

■Processing of the defining portion, that is, in both the first and second inventions of the present invention, first, the portion that defines the track width, which requires high precision, is preferably processed by the applicant in an atmosphere containing halogen or a halide. In an atmosphere containing halogen or halide at 10 to 200 Torr, a laser beam of 20 pm or less with a power of 50 to 1100 mW is heated at 2 to 110 μm as described in Japanese Patent Application Laid-Open No. 63-45387.
By irradiating at a scanning speed of m/sec and processing by laser-induced etching, processing with higher precision can be performed although it takes some processing time.

The conditions for achieving a machining depth of 20 μm or more, which is required for a normal magnetic head core, while maintaining a surface roughness of 2 μm or less and at an industrially acceptable machining speed are as follows:
Laser power is 50-1100mW.

The relative beam scanning speed is in the range of 2 to 110 μm/see, and when the laser power is kept constant within the above range, the upper limit of the scanning speed is determined by the processing depth and surface roughness. Furthermore, the surface roughness is 1μm or less and 20μ
The conditions for achieving a machining depth of m or more are a laser power of 50 to 650 mW and a relative beam scanning speed of 2 to 650 mW.
A range of 100 μm/sec is required, and when the laser power is kept constant within the above range, the upper limit of the scanning speed is determined by the processing depth and surface roughness.

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, a gas containing halogen or halide gas is suitable as the atmospheric gas, and among them, CCl4 is
It is stable and relatively low in toxicity, making it easy to handle.

In addition, in order to efficiently remove the workpiece by a thermochemical reaction, it is necessary to promptly remove the halide gas of the ferrite component element, which is a chemical reaction product, from the processing point, and to A sufficient amount of halogen or halogen compound-containing gas must be newly supplied. Therefore, the degree of vacuum of the atmosphere, that is, the gas pressure of the gas containing halogen or halide must be controlled within an appropriate range. When the gas pressure exceeds 200 Torr, it becomes difficult to volatilize the halide gas of the ferrite component element, which is a chemical reaction product, and the reaction product adheres to the processed surface and its surroundings, causing surface roughness. becomes lower. Also, depending on the amount to be removed and the shape to be processed, the width is 3
When drilling a hole with a depth of 50 μm and a depth of 50 μm, the gas pressure is 10 μm.
At temperatures below Torr, the surface to be processed takes on the appearance of a thermally processed surface, similar to conventional laser processing. Therefore, the gas pressure of gas containing halogen or halide is 10 to 2
It is desirable to set it to 00 Torr, and more preferably to set it to 40 to 100 Torr.

Furthermore, it is not always necessary to keep the atmosphere sealed during processing, and a method of circulating gas is also effective.

One such method is to forcibly supply a gas containing halogen or halide to the vicinity of the processing point using a nozzle or the like, which is effective for removing reaction products and supplying new gas. Furthermore, it is economically effective to carry out the laser etching at room temperature, and it is also possible to perform the processing under weak laser power after preheating to 500°C or less.

If the laser beam convergence diameter is 20 μm or less, the initial surface roughness and machining depth can be obtained, but the beam convergence diameter affects the removal of the workpiece at the machining point, so the machining conditions must be selected. In addition, it is necessary to take into consideration the convergence diameter of the laser beam, the gas pressure, and the temperature of the workpiece. In principle, the wavelength of the laser should be 20 μm or less in relation to the above-mentioned beam convergence diameter, and is appropriately selected within the range of 20 μm or less, taking into account the ability of the lens and other various conditions. Various lasers such as YAG, Co□, and Ar+ ion lasers can be used as laser light sources that meet this condition, but Ar' ion lasers are more suitable because of their excellent oscillation stability and small spread angle of laser light. used.

■ Machining other than specified parts Machining of parts that define the track width requires high precision and low machining distortion, but these may not be as important when machining other parts. Most of them. Therefore, it is advantageous in terms of reducing machining time to process parts other than the parts that define the track width using a method that has a relatively fast machining speed after or prior to machining the parts that define the track width. It is.

Therefore, in the present invention, areas other than the areas that define the track width are etched in an aqueous solution of alkali metal hydroxide (the first invention) or in a phosphoric acid solution, which enables faster processing than the laser-induced etching in the gas described above. Processing is performed by laser-induced etching in the middle (second invention).

That is, for a gap bar having a coil winding hole and a magnetic gap, a predetermined laser beam is applied to the gap bar surface in an aqueous solution of an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide or in a phosphoric acid solution. By irradiating at a scanning speed of cause a flow towards the rear of the Therefore, alkali metal hydroxide or phosphoric acid is constantly supplied to the processing point, and at the same time, cutting waste is quickly removed from the processing point, and laser-induced etching progresses. As a result, if grooves or holes are processed by the laser-induced etching of the present invention to form tracks, problems such as melting and solidification of the workpiece, processing distortion and deterioration due to heat, and cranking in conventional laser processing can be solved. I can do it.

The magnetic head core is made by forming a track by cutting grooves or holes to define the track width in a gap bar made of ferrite, sendust, etc. by laser-induced etching, and then adding glass to reinforce the track as necessary. The process of embedding inside the groove or hole, polishing the sliding surface until 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, the depth, reaches the required dimension. It is obtained through a process and further post-processing such as slicing into the required core width.

Depth is approximately 30μm for VTR and FDD, RDD
It is about 5 μm. Therefore, when forming a trunk for this gap bar, the depth of the groove or hole used to define the track must be at least 10 μm, taking into account post-processing such as polishing the sliding surface. Yes, preferably 30 μm or more, more preferably 50 μm
The above is necessary. Further, the dimensional accuracy for defining the track needs to be ±2 μm 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 alkali metal hydroxide or phosphoric acid, resulting in adhesion of molten solids and cracks on the machined surface. This will cause dimensional accuracy to deteriorate. Furthermore, if the scanning speed becomes too high, a sufficient chemical reaction cannot occur, and the same tendency occurs.

Therefore, in the first aspect of the present invention, in order to process the core for a magnetic head, a laser power of 50 mW or less is insufficient to cause laser-induced etching, and the required depth of 10 μm or more is insufficient. can't get it. Furthermore, in order to be able to implement this laser-induced etching industrially, compared to conventional machining, it requires 1
It is desirable to process in 30 seconds or less per track.
The scanning speed needs to be at least 2 μm/sec or more. The conditions for processing the track of the magnetic head core with a dimensional accuracy of ±2 μm or less, a processing depth of 10 μm or more, and at an industrially practicable processing speed are the laser power, which is the limiting condition in the first invention of the present invention. P is 50-1300m
The scanning speed V is in the range of 2 to 150 μm/sec, and the relational expression ■≦0.34P+13 and the relational expression ■≦−0
, 17P + 217 (
(See Figure 3 below).

In addition, in the second aspect of the present invention, in order to process the core for a magnetic head, a laser power of 50 mW or less is insufficient to cause laser-induced etching, and a depth of 10 μm or more is required. can't get it. Furthermore, in order to be able to carry out this laser-induced etching industrially, compared to conventional machining, it is desirable to perform the processing in 30 seconds or less per track, and the scanning speed must be at least 2 μm/sec or more.

The conditions for machining a track with a dimensional accuracy of ±2 μm or less and a machining depth of 10 μm or more at an industrially practicable machining speed are a laser power P of 50 to 1900 mW, which is a limiting condition in the second invention of the present invention. .

The scanning speed ■ is in the range of 2 to 200 μm/sec,
And the relational expression ■≦0.31 P +34 and the relational expression ■≦−0
, 14P+271 (see FIG. 4, which will be described later).

In this laser-induced etching method, an aqueous alkali metal hydroxide solution or phosphoric acid aqueous solution acts as an etching solution for the gapper that is the workpiece. Iron, the main component of ferrite and sendust, is well etched into alkali metal hydroxides or phosphoric acid. The machining depth also changes depending on the concentration of the alkali metal hydroxide aqueous solution or phosphoric acid aqueous solution. The higher the concentration, the greater the machining depth; however, if the concentration is too high, etching progresses excessively, roughening occurs on the machined surface, and dimensional accuracy decreases. On the other hand, if the concentration is too low, the amount of chemical reaction will decrease and sufficient laser-induced etching will not occur, making it impossible to obtain the required processing depth. Therefore, the concentration of the aqueous alkali metal hydroxide solution needs to be 5 to 55 wt%, and the concentration of the phosphoric acid aqueous solution needs to be 10 to 90-t%.

The convergence diameter of the laser beam is 20. If it is less than cnn, the required processing depth and dimensional accuracy can be obtained, but the convergence diameter of the laser beam will affect the processing shape, etc.
In selecting processing conditions, it is also necessary to consider the relationship between the convergence diameter of the laser beam and the concentration of the alkali metal hydroxide aqueous solution or phosphoric acid aqueous solution.

Various lasers can be used as a laser light source, but since ferrite and sendust have a high absorption rate at wavelengths of 1 μm or less, Ar ion lasers and YAG lasers, which have excellent oscillation stability and a small spread angle of laser light, are preferable. 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 carrying out the laser-induced etching of the present invention in an atmosphere of gas such as halogen. 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 halide. Furthermore, a quartz window 5 is provided on the top surface of this chamber 1.
Laser light from a laser light source 6 disposed above the quartz window 5 is irradiated into the chamber 1 through the quartz window 5.

In the chamber 1, the following gapper 11 to be etched is placed on the sampling holder 3, and the gapper 11 is subjected to laser-induced etching using the following means and conditions. There is.

That is, 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 CCP gas at a predetermined pressure. The vapor pressure of this CCL gas is about 60 Torr at room temperature, and this value is used as is in this invention. Next, the surface of the gapper 11 is irradiated with, for example, an Ar4 ion laser beam 7 (wavelength 514.5 nm, focal diameter 2.5 μm), the gapper 11 is scanned by an XY child table, and heated to a predetermined position. It causes a chemical reaction.

FIG. 2 is a diagram showing an example of an apparatus for carrying out the laser-induced etching of the present invention in an aqueous solution of alkali metal hydroxide or phosphoric acid. In this embodiment, the X-Y table 21
A processing container 22 is placed in the processing container 22, and a sample stage 2 is placed inside the processing container 22.
3 and the gapper 24 which is the workpiece placed on it
is located. The inside of the processing container 22 is filled with a phosphoric acid aqueous solution 25, and the gapper 24 is
The liquid level height of the alkali metal hydroxide or phosphoric acid aqueous solution 25 above is controlled. If the liquid level height is too small, the flow of the liquid will be slow and the aqueous solution will be excessively heated and bubbles will be generated easily, resulting in a decrease in the machining depth and a decrease in dimensional accuracy. When the liquid level is 200 μm or more, this effect is almost non-existent, but if the liquid level is too high, the amount of light lost while the laser beam passes through the aqueous solution increases, reducing the machining depth and causing problems with the flow of the liquid. This occurs as a convection in the vertical direction of the liquid surface, so cutting chips and air bubbles discharged from the machining point are picked up by this convection, scattering the laser light, and reducing the machining depth and dimensional accuracy. causing a decline. Therefore,
The liquid level height is desirably 200 μm or more, more preferably 300 to 1 ooooo μm.

Note that the quartz window 27 controls the liquid level height, and at the same time eliminates fluctuations in the liquid level and improves processing accuracy.

Laser light 28 is emitted from a laser light source 29 and is irradiated onto gapper 24 through lens system 30 and quartz window 27 . At this time, by moving the χ-Y table 21, a desired shape can be processed.

■Determination of processing conditions In the present invention, using the above-mentioned apparatus, first, the portions that define the track width are processed by laser-induced etching in an atmosphere containing halogen or halides, and then etched with alkali metal hydroxide. Laser-induced etching is performed in an aqueous solution (first invention) or laser-induced etching is performed in an aqueous phosphoric acid solution (second invention).

The case where the present invention is applied in an aqueous solution of an alkali metal hydroxide or an aqueous solution of phosphoric acid will be described below.

(i) Machining in an aqueous solution of alkali metal hydroxide Figure 3 is a graph showing the range of conditions for track machining of a magnetic head core with a machining depth of 10 μm or more and a dimensional accuracy of ±2 μm or less. . This range is the laser power P
is 50-1300mW, scanning speed V is 2-150μm/
The upper limit of the scanning speed in the range of sec and when the laser power is constant is a processing depth of 10 μm.
It can be understood that the range is limited by ≦0.34P+13 (solid line) and the relational expression V≦-0,17P+217 (broken line) indicating a dimensional accuracy of ±2 μm.

From Fig. 3, it is possible to obtain a machining depth of 10 μm or more with a dimensional accuracy of ±2 μm or less at a laser power of 300 mW and a scanning speed of 2 to 115 μm/sec, but with the same power and a scanning speed of 115 μm/sec. sec~1
It can be seen that in the range of 65 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. Furthermore, the scanning speed is 1658mls
It can be seen that dimensional accuracy of ±2 μm or less cannot be obtained at ec or more. Furthermore, when the laser power is 500 m, 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 135 μm/sec.
With the same power and scanning speed within the range of 135 to 185 μm/sec, a machining depth of 110l1 or more can be obtained, but ±
It can be seen that dimensional accuracy of 2 μm or less cannot be obtained. Furthermore, it can be seen that at a scanning speed of 185 μm/sec or more, a machining depth of 10 μm or more cannot be obtained.

The conditions shown in FIG. 3 above are based on experimental results under conditions where the potassium hydroxide aqueous solution concentration is 5 to 55 wt%, the sodium hydroxide aqueous solution concentration is 5 to 55 ivt%, and the laser beam diameter is 20 μm or less. However, even if the laser power and scanning speed are constant, the processing depth and dimensional accuracy will vary if the concentration or laser beam diameter changes. Therefore, appropriate conditions for the desired machining depth and dimensional accuracy must be selected within the range shown in FIG. 3 above, taking into account the concentration and laser beam diameter.

Especially regarding the laser beam diameter, when reducing the laser beam diameter, the laser power should be lowered to prevent the amount of melting due to the heat of the laser beam from becoming larger than the amount of chemical reaction with potassium hydroxide and sodium hydroxide. It is preferable. Conversely, when increasing the laser beam diameter, it is preferable to increase the laser power in order to sufficiently cause laser-induced etching.

(ii) Machining in an aqueous phosphoric acid solution FIG. 4 is a graph showing the range of conditions for machining with a machining depth of 10 μm or more and a dimensional accuracy of ±2 μm or less.

In this range, the laser power P is 50 to 1900 mW,
The scanning speed V is in the range of 2 to 200 tt m/sec,
In addition, the upper limit of the scanning speed when the laser power is constant is the relational expression ■≦0.31P+3 which indicates that the processing depth is 10 mm.
4 (solid line) and the relational expression showing dimensional accuracy ±2μm■≦-0
, 14P+271 (broken line).

From Figure 4, for example, a machining depth of 10 μm or more can be obtained with a dimensional accuracy of ±2 μm or less with a laser power of 300 mW and a scanning speed of 2 to 130 μm/sec, but with the same power and a scanning speed of 130 μm/sec. sec~2
It can be seen that in the range of 30 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. Furthermore, the scanning speed is 230μwl/
It can be seen that above SeC, dimensional accuracy of ±2 μm or less cannot be obtained. Furthermore, when the laser power is 600 m-, a processing depth of 10 μm or more can be obtained with a dimensional accuracy of ±2 μm or less when the scanning speed is within the range of 2 to 185 tt m/sec, but at the same power and the scanning speed is 185 to 225 p.
It can be seen that within the range of m 2 /sec, a machining depth of 108 m or more can be obtained, but a dimensional accuracy of ±2 μm or less cannot be obtained. Furthermore, it can be seen that at a scanning speed of 225 μm/sec or more, a machining depth of 10 μm or more cannot be obtained.

The conditions shown in Figure 4 above are such that the concentration of the phosphoric acid aqueous solution is 10W.
t% to 90wt%, laser beam diameter is 50. Based on experimental results under conditions below czm. However, even if the laser power and scanning speed are constant, the processing depth and dimensional accuracy will vary if the concentration or laser beam diameter changes. Therefore, appropriate conditions for the desired processing depth and dimensional accuracy must be selected within the range shown in FIG. 4 above, taking into account the concentration and laser beam diameter.

In particular, 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 phosphoric acid. Conversely, when increasing the laser beam diameter, it is preferable to increase the laser power in order to sufficiently cause laser-induced etching.

(2) Preparation of core for magnetic head (i) Concept of manufacturing method of the present invention FIGS. 5(a) to 5(C) are perspective views showing an example of the manufacturing process of the manufacturing method of the present invention, respectively. First, Figure 5(a)
As shown in FIG. 2, a gapper 53 is obtained by joining a ferrite rod 51a and a ferrite rod 51b having grooves 52 corresponding to the coil winding holes by means such as glass welding.

Next, as shown in FIG. 5(b), the gap 54-1.
The track width 54-2 is defined by laser-induced etching in an atmosphere containing halogen or halide under predetermined conditions. Finally, Figure 5 (C)
As shown in FIG.
Alternatively, the grooves 55 are formed by laser-induced etching in an aqueous phosphoric acid solution (second invention).

Table 1 lists suitable conditions when actually processing a magnetic head core made of ferrite and a magnetic head core made of ferrite and sendust by the above method.

(ii) Production of magnetic head core made of ferrite FIGS. 6(a) to 6(e) are perspective views showing an example of the manufacturing process of a VTR head core according to the present invention.

First, as shown in FIG. 6(a), a ferrite rod 71a
and a ferrite rod 71b having a coil winding hole 72 are bonded together by glass bonding, solid phase reaction bonding, or the like to form a gapper 64 having a magnetic gap 71.
form. Next, the laser power was 400 mW, the scanning speed was 20 μm/sec, and the laser beam diameter was 2.5 pm.
, CG! Under an atmospheric condition of 460 Torr, the prepared gear knob bar 64 is attached to the device shown in FIG. 1, and a groove 74 defining a track width 73 is formed in the gapper 64 as shown in FIG. 6(b). Process multiple pieces. next,
Laser power 400 mW, scanning speed 20 p m/s
ec.

Laser beam diameter 10μm, phosphoric acid aqueous solution concentration 77wt
%, the liquid level height is 500 μm, and the gapper 64 after machining the part that defines the track width 73 is mounted on the device shown in FIG. A plurality of locations other than the groove 74 defining the track width 73 are machined. Next, as shown in FIG. 6(d),
Glass 75 is embedded in the processed groove 74 and polished to a predetermined size. Finally, this was cut into a predetermined width to obtain a core 76 for a VTR head as shown in FIG. 6(e). The magnetic head core 76 thus obtained was highly reliable, with highly accurate tracks formed without adhesion of cranks or molten matter.

(iii) Production of MTG magnetic head core made of ferrite and sendust Figures 7(a) to (h) show an example of the manufacturing process according to the present invention for a composite VTR magnetic head core made of ferrite and sendust, respectively. FIG.

First, as shown in FIG. 7(a), a ferrite rod 81a
As shown in FIG. 7(b), a sendust film 84 with a thickness of 5 μm is formed on the gap facing surface 83 of the ferrite rod 81b having grooves 82 corresponding to the coil winding holes, and After forming a non-magnetic material 85 such as SiO□, which will serve as a magnetic gap, as shown in FIG. A gapper 91 having a magnetic gap 85 as shown in Figure (d) is formed. Next, the laser power was 400 ml, and the scanning speed was 20 ml.
μm/sec, laser beam diameter 2.5 pm XC
Under an atmosphere of Cj2460 Torr, the prepared gapper 91 was installed in the device shown in FIG.
As shown in Figure (e), the gap par 91 has a trough width 92.
A plurality of grooves 93 are machined. Next, the laser power was 500 mW, the scanning speed was 30 μm/sec, the laser beam diameter was 4 μm, and the potassium hydroxide aqueous solution concentration was 30%.
, Under the condition that the liquid level height is 500 μm, the gapper 91 after processing the part that defines the track width 92 is installed in the device shown in FIG. 2, and the track width 92 is defined as shown in FIG. The glass 8 is placed inside the groove 86 which is machined at a location other than the location.
8 is embedded as shown in FIG. 7(g) and polished to a predetermined size. Finally, cut it out to the specified width and cut it into the seventh
A composite VTR head core 88 as shown in Figure (h) was obtained. The magnetic head core 88 thus obtained had highly reliable tracks formed with no cracks or adhesion of molten matter.

Note 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 RDDs and FDDs. Furthermore, the present invention is not limited to I/rack processing, but includes various processing of ferrite materials, sendust materials, and composite materials of ferrite and sendust, such as coil winding hole processing and air bearing surface processing of cores for RDD magnetic heads. It is also suitably used.

(Effects of the Invention) As described above, according to the manufacturing method of the present invention, the portion that defines the track width is processed by laser-induced etching in an atmosphere containing halogen or a halide, and the track width is also defined. Since the other parts are processed by laser-induced etching in an aqueous solution of alkali metal hydroxide or phosphoric acid under specified conditions, there is no adhesion of molten solids or molten scatterings to the gap bar, and there is no heat-induced There is no deterioration, processing strain, or crank associated with it, and narrow, high-precision tracks can be formed at high speed, making it possible to manufacture highly reliable magnetic head cores in a short time.

[Brief explanation of drawings]

Figures 1 and 2 are conceptual diagrams showing an example of an apparatus implementing the present invention, respectively. Figure 3 shows a magnetic head core machined to a depth of 10 μm or more using an aqueous solution of alkali metal hydroxide, with a dimensional accuracy of ±2 μm.
The following graph shows the range of conditions for 1-rack machining. Figure 4 shows the conditions for track machining with a phosphoric acid aqueous solution to a magnetic head core with a machining depth of 10 μm or more and a dimensional accuracy of ±2 μm or less. Graphs showing the range, FIGS. 5(a) to (C) are perspective views showing an example of the manufacturing process of the manufacturing method of the present invention, and FIGS. 6(a) to (e) are respectively the second graphs of the present invention. A perspective view showing the processing procedure when the invention is applied to the manufacture of a core for a VTR magnetic head, and FIGS. FIG. 3 is a perspective view showing a processing procedure when applied to manufacturing a core for a head. 51a, 51b... Ferrite rod 52... Groove 53... Gap bar 54-1.54-2... Gap

Claims (1)

[Claims] 1. In a manufacturing method in which a magnetic head core is formed by laser processing, a portion that defines the track width is processed by laser-induced etching in an atmosphere containing halogen or a halide, except that the track width is defined. 20 μm with a power P of 50 to 1300 mW in an aqueous solution of alkali metal hydroxide with a concentration of 5 to 55 wt%.
A laser beam with the following diameter is scanned at a scanning speed V of 2 to 150.
A core for a magnetic head characterized in that it is irradiated at a scanning speed that simultaneously satisfies the relational expressions V≦0.34P+13 and V≦-0.17P+217 in the range of μm/sec, and is processed by laser-induced etching. Production method. 2. In a manufacturing method in which a magnetic head core is formed by laser processing, the portions that define the track width are processed by laser-induced etching in an atmosphere containing halogen or halides, and the portions other than those that define the track width are etched with a concentration of 10. 50-1 in ~90 wt% phosphoric acid aqueous solution
A laser beam with a diameter of 50 μm or less and a power P of 900 mW is scanned at a scanning speed V of 2 to 200 μm/sec using the relational expressions V≦0.31P+34 and V≦−0.14.
A method for manufacturing a core for a magnetic head, characterized in that the core is irradiated at a scanning speed that simultaneously satisfies the relational expression P+271 and processed by laser-induced etching.