JPH06290418A - Magnetic head and its production - Google Patents

Abstract

PURPOSE:To stably assure electromagnetic conversion characteristics without making a gap length substantially larger than the intrinsic gap length. CONSTITUTION:Code blocks 101A, 101B are integrated by fusion of fusing glass 8 holding an SiO2 film 7 therebetween. The gap length L1 is made slightly larger than the intrinsic gap length L by erosion (regions 9, 10) by the fusing glass 8 near the deepest position 0 of the magnetic gap but the gap length remains at the intrinsic gap length L in the position shown by an A-A line which is the surface of the finished core. The reason thereof lies in that the length in the depth length direction of the erosion regions mentioned above is reduced to <=1/2 the standard length of the depth (the size between the zero point and the A-A line).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head and its manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a magnetic head for, for example, a floppy disk, there is one having a structure as shown in FIGS. 18 to 21 (here, for 4 MB).

This magnetic head is shown as a composite head.
As shown in FIGS. 18 and 19, a main core 23 having a recording / reproducing magnetic gap G1 and an erasing magnetic gap G2, and a cross-section substantially E
Character-shaped auxiliary core (back core) 26 and drive coil 24
A magnetic circuit portion is constituted by a pair of coil bobbins 24 and 25 around which a and 25a are wound. And the main core 23 is
A pair of sliders 20 and 22 sandwich and fix the slider in order to secure the contact characteristics with the floppy disk.

The main core 23 and the auxiliary core 26 are
The coil bobbins 24 and 25 are joined to each other, and are pressed and supported by a U-shaped metal leaf spring 27 to form a magnetic coupling. These head components are housed in the magnetic shield member 28 after being assembled.

The magnetic head 29 thus configured
Is temporarily fixed to a predetermined position on the head mounting surface of the gimbal 30 with an instant adhesive. The magnetic head 29 is coated with an ultraviolet curable resin 32 between the side wall surfaces of the sliders 20 and 22 and the head mounting surface to be adhesively reinforced, and then covered with a magnetic shield member 28, both of which are gimbaled by the resin 32. Fixed at 30.

The gimbal 30 having the magnetic head 29 mounted thereon is further coupled to a flexible printed circuit 41 which is a head supporting member.

Thus, as shown in FIG. 21, the magnetic head assembly having the magnetic head 29 is mounted rotatably in the direction of the arrow X in FIG. The carriage 62 and the magnetic heads 29 provided on the tip side of the movable arm 63 perform recording and reproduction on both sides of the floppy disk 42. By the pivots 64 and 65, the contact state of the magnetic head 29 with the disk 42 is always kept constant.

As a magnetic head for a floppy disk, a composite magnetic head in which a recording / reproducing magnetic head portion and an erasing magnetic head portion are integrated is used. This composite magnetic head has a high capacity of 4 megabytes (4 MB). And, as shown in FIG. 31, the core is composed of a main core 90 and an auxiliary core 91.

The magnetic gaps G ₁ and G ₂ of the main core 23 shown in FIG. 18 have a predetermined depth length by grinding after several steps from the material enlarged and shown in FIG. In addition,
FIG. 17 shows an ideal state.

That is, the side core material block 101A and the center core material block 101B are fused and integrated by glass 7 with a film 6 of SiO ₂ or the like, which is formed by sputtering and becomes a magnetic gap having a predetermined size, sandwiched therebetween.
It consists of 16 materials.

Then, in a later step, by grinding, A-
The magnetic gap G ₁ (or G ₂ ) is formed by scraping from the surface of the material indicated by the line A to the surface of the finished core product indicated by the line BB. Since the gap length L has a great influence on the electromagnetic conversion characteristics, it is required that the gap length L is highly accurate and does not significantly change in the depth length D direction.

Mn-Zn type ferrite is used as the core material, and SiO ₂ -PbO type high melting point glass is used as the glass for fusing. The high-melting-point glass is used in order to prevent melting or softening due to subsequent fusion for forming the center glass.

Conventionally, in the state of the core material block before being sliced to form a head chip, the gap length is inspected on the surface (a line AA line) shown in FIG. The gap length of the head core sandwiching the chip is inspected (position BB in FIG. 16). However, of the core material blocks that passed the above inspection, 10% or more of them failed the head core inspection.

For example, while the average gap length in the core material block was 0.379 μm, the average gap length in the head core was 0.406 μm, and the average gap length was expanded by 0.027 μm. From this, it is considered that the gap length in the core material block is larger in the inner part.

As described above, many rejected products are generated from head cores manufactured through many steps even though they have passed the inspection once, which means that these rejected products cost much. It will be discarded after a long time, which is very economically inconvenient.

As a result of a study conducted by the present inventors, the regions of the core material blocks 101A and 101B facing the SiO ₂ film 6 when fused with the glass 7 react with the molten glass melted by the fused glass 8 and are shown in FIG. As such, it was found to be eroded by this molten glass.

The erosion regions 9 and 10 become non-magnetic and function as a magnetic gap, and the erosion regions including the depth length direction are in the track width direction (gap width direction).
If this occurs, the electromagnetic conversion characteristics will be adversely affected.

In FIG. 22, the erosion regions 9 and 10 extend beyond the position of the line BB to the inside. In this case, the length L ₂ of the regions 9 and 10 in the depth direction extends over the entire depth direction of the magnetic gap in the finished product, and the gap length becomes wider than the original gap length. In the 4 MB head, the gap length and the depth length are ½ of those in the 2 MB head, so that the gap length is likely to change.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses the erosion of the core by the fusion material, and the change in the gap length of the magnetic gap is small, which is excellent electromagnetic conversion. It is an object of the present invention to provide a magnetic head whose characteristics are guaranteed and a manufacturing method thereof.

[0020]

That is, according to the present invention, a first core and a second core are fused by a fusion material, and a magnetic gap formed between the first and second cores is formed. A magnetic head in which the length in the depth length direction of the portion of the first core and / or the second core that is eroded by the fusion material is less than or equal to 1/2 of the depth standard length Is.

In the present invention, it is preferable that the core is made of ferrite and the fusing material is made of silicon oxide-lead oxide.

According to the present invention, when fusing the first core material and the second core material with the fusing material, 670 to 700
The present invention relates to a method of manufacturing a magnetic head, which has a step of heating at a temperature in the range of ° C for about 90 minutes or more to perform fusion bonding. In the method of the present invention, it is desirable to carry out the fusion in a non-oxidizing atmosphere.

In the method of the present invention, the first and second core materials made of ferrite are used, and silicon oxide-
It is desirable to use a fusion material made of lead oxide.

[0024]

EXAMPLES Examples of the present invention will be described below.

First, the manufacturing process of the head chip (the material immediately before the main core in FIG. 18) will be described with reference to FIGS.

First, the ferrite block 101 shown in FIG.
(Both main surface lap finish) was prepared, and multiple
As described above, the jig 2 made of hardened steel is fixed with wax.

Next, the block 101 is ground as shown in FIG. 6 to obtain one block from each block.
101A and 101B are cut out, and a plurality of grooves 4 and grooves 6 between the grooves 4 are put in parallel in the length direction of the block 101A.

Next, as shown in FIG. 7, both blocks 101A
A large number of grooves 5 for forming magnetic gaps are formed in parallel with each other in 101B and orthogonal to the grooves 4 and 6.

After the grooving process, the surface of each block is lapped to be mirror-finished and removed from the jig 2. This state is shown in FIG.

Next, after the blocks 101A and 101B are vapor-deposited with a gap spacer 7 made of SiO ₂ or the like on the gap facing surface (shown in an enlarged sectional view in FIG. 9), primary tracks are aligned as shown in FIG. They are bonded and integrated with each other by a glass (not shown) (primary fusion).

At the time of this primary fusion bonding, both blocks 101
A and 101B are brought into contact with each other on the side facing the gap, and a fusion-bonding glass rod (not shown) is inserted into each groove 4, 6 while applying pressure from both sides using a fusion-bonding jig (not shown). Then, it is heated and melted, and further cooled. The primary fusion is performed by holding the temperature in the range of 670 to 700 ° C. for about 90 minutes or more in a non-acidified atmosphere (dry nitrogen atmosphere in this example).

Next, as shown in FIG. 11, the block 101B is ground to form a thin center core 101B.

Then, a pair of blocks shown in FIG. 11 is produced as shown in FIG. 12, and these are secondarily fused together with a center glass (not shown) as shown in FIG.

Next, this fused body is divided into two at the position of the groove 6 as shown in FIG. 14, and further sliced into individual head chips 123 as shown in FIGS. 15 and 16. These head chips 123 are sandwiched and fixed between the sliders 20-22 described above, and finally processed into the shape shown in FIGS. 18 and 19 by grinding.

Head chip manufactured as described above
123 is a core material made of fused glass by performing the primary fusion in a dry nitrogen atmosphere and by heating and holding it at a temperature within the range of 670 to 700 ° C (previously 720 ° C). Was slightly eroded and had substantially no adverse effect on electromagnetic conversion characteristics.

FIG. 1 is an enlarged partial front view similar to FIGS. 17 and 22, showing the state of core material erosion in this example.
As shown in the figure, the areas 9 and 10 of core material erosion are significantly smaller than those of FIG. 22, and the depth direction length L ₁ of the erosion area remains within the range of 1/2 or less of the depth length L. There is. That is, the gap length near the innermost part of the magnetic gap is larger than the original gap length, but the gap length is the same as the original gap length at the position of the line BB.

Next, the results of experiments conducted on the relationship between the heating temperature of the primary fusion and the degree of core material erosion by the fusion glass will be described.

The core material is Mn--Zn type ferrite, and the composition thereof is 70.045% Fe ₂ O ₃ by weight, 17.67.
% MnO, 12.285% ZnO, 0.05% ZnO ₂ . Fused glass is a high melting glass of silicon oxide-lead oxide,
Its composition is ≧ 30% by weight ratio SiO ₂ .PbO, 0.1-
A _{10% NaO · B 2 O 3} · Fe 2 O 3 · ZnO. Atmosphere gas at the time of fusion is dry nitrogen, and fusion temperature is 700
℃, 690 ℃, 680 ℃, 670 ℃, holding time is 90 minutes.

After fusion, as shown in FIG. 3 (a), 5 chip cores were sampled from the material block, and the gap length was measured at 18 points in the depth direction of the Tw width center shown in FIG. 3 (b). did. Use a 50K scanning electron microscope for measurement,
The platen supporting the chip core is a tin platen having a diamond finish of 1/4 μm.

The measurement points are the positions indicated by a to r in FIG. The distance from the deepest position of the magnetic gap called depth 0 is 5 μm for a and r, 10 μm for b and q, and c and p.
Is 13 μm, d and o are 17 μm, e and n are 21 μm, f and m are 80 μm, and g and l are 117 μm. Central groove 6
The distance from the side edge of is 10 μm for h and k, and 5 for i and j
μm.

The measurement results are as shown in FIG. For comparison, the same figure also shows the measurement results for the fusion temperature of 720 ° C. and the same as above (conventional method).

In the type of magnetic head in this example,
The depth length is standardized with a value within the range of 13 to 21 μm. In the conventional fusion method at 720 ° C, the erosion area extends to the depth standard length of 18 μm in the depth length direction. On the other hand, when the fusion temperature is 700 ℃, it is reduced to about 10.6μm, which is about half of that, and when the fusion temperature is further lowered, it is 7.2 at 690 ℃.
μm, 5.2 μm at 680 ° C and 3.4 μm at 670 ° C.

For example, in the case of a magnetic head having a depth standard length of 17 ± 4 μm, the erosion region stops at ½ or less of the depth standard length at a fusion temperature of 690 ° C. or lower. Also, the variation in the gap length is significantly smaller (about 1/3) at a fusion temperature of 700 ° C or lower, compared to 0.029 μm at the fusion temperature of 720 ° C. If the fusing temperature is lower than 670 ° C, fusing becomes uncertain.

From FIG. 2, by setting the fusion temperature to 700 ° C. or less, the erosion region is suppressed to 1/2 or less of the depth standard length, the gap length accuracy is improved, and the electromagnetic conversion characteristics are good and stable. You can understand what to do.

Although the embodiments of the present invention have been described above, the above embodiments can be further modified based on the technical idea of the present invention.

For example, the material of the core may be Mn-Zn-based ferrite, other ferrite, or a magnetic material other than ferrite (for example, permalloy or the like),
The high melting point glass may also be a glass other than the SiO ₂ —PbO system or another fusing material.

Further, although the erosion due to the fused glass usually occurs on both of the pair of cores, the erosion may occur on only one core.

Further, the present invention is for a floppy disk of 4 MB, and for a floppy disk of another size,
Alternatively, it can be applied to a head for a magnetic recording medium other than a floppy disk.

[0049]

According to the present invention, the fusion of the core material with the fusion material is performed at a temperature within the range of 670 to 700 ° C., and the length of the eroded portion of the core with the fusion material in the longitudinal direction of the magnetic gap depth is determined. Since the depth standard length is 1/2 or less, the increase in the gap length of the magnetic gap due to the eroded portion can be substantially eliminated.

As a result, the accuracy of the magnetic gap does not substantially decrease, stable and good electromagnetic conversion characteristics are guaranteed, and the yield is improved.

[Brief description of drawings]

FIG. 1 is an enlarged partial front view of a head chip according to an embodiment.

FIG. 2 is a graph showing the relationship between the fusion temperature and the core erosion state.

FIG. 3 is a schematic diagram for demonstrating a procedure for measuring the gap length of the magnetic gap.

FIG. 4 is a perspective view showing one process step in manufacturing the magnetic head.

FIG. 5 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 6 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 7 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 8 is a perspective view showing another process step of manufacturing the magnetic head.

9 is an enlarged cross-sectional view in the process of FIG.

FIG. 10 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 11 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 12 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 13 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 14 is a perspective view showing another process step of manufacturing the magnetic head.

FIG. 15 is a perspective view showing still another process step at the time of manufacturing the same magnetic head.

FIG. 16 is a perspective view showing a head chip cut out when the magnetic head is manufactured.

FIG. 17 is an enlarged partial front view similar to FIG. 1 of the head chip in an ideal state.

FIG. 18 is a perspective view showing a head chip of a conventional magnetic head for a floppy disk.

FIG. 19 is an exploded perspective view of the magnetic head.

FIG. 20 is a perspective view of the same magnetic head attached to a gimbal and a flexible printed circuit.

FIG. 21 is a schematic cross-sectional front view showing a usage state of the magnetic head.

FIG. 22 is an enlarged partial front view of the same head chip as in FIG. 1.

[Explanation of symbols]

1A, 1B, 101, 101A, 101B ... Ferrite block or core 4, 5, 6 ... Groove 7 ... SiO ₂ film 8 ... Fused glass 9, 10 ... Erosion region of core material 23, 123 ・ ・ ・ Head chip 29 ・ ・ ・ Magnetic head G ₁ , G ₂・ ・ ・ Magnetic gap L, L ₁ , L ₂・ ・ ・ Gap length

Claims (5)

[Claims] 1. A first core and a second core are fused by a fusion material, and in the region of a magnetic gap formed between the first and second cores, the first core and the second core / Or the magnetic head in which the length of the portion of the second core that is eroded by the fusion material in the depth length direction is ½ or less of the depth standard length. 2. The magnetic head according to claim 1, wherein the core is made of ferrite and the fusing material is made of a silicon oxide-lead oxide system. 3. When fusing the first core material and the second core material with a fusing material, a step of heating to a temperature within a range of 670 to 700 ° C. for about 90 minutes or more to perform fusing Have,
A method of manufacturing a magnetic head according to claim 1. 4. The method of manufacturing a magnetic head according to claim 3, wherein the fusion bonding is performed in a non-oxidizing atmosphere. 5. The method of manufacturing a magnetic head according to claim 3, wherein the first and second core materials made of ferrite are used, and the fusion material made of silicon oxide-lead oxide is used. .