JPH0557642B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to thin film magnetic heads.
A thin film magnetic head is usually formed to have the cross-sectional shape shown in FIG. That is, the lower core 2 is disposed on the base 1, the first insulator layer 3 is further provided thereon, and then the second insulator layer 3 is provided on the first insulator layer 3.
A first coil portion 4 having a planar shape as shown in FIG. A second coil part 6 having an end 6a connected to the end 4a is provided on top of the second coil part 6 as shown in FIG. The upper core 8 is arranged from above the body layer. Incidentally, the track width of this magnetic head is defined by the width P of the upper core 8 (FIG. 2 c), and the upper and lower cores 2, 8
The gap length is defined by the distance Q. The distance Q is between the first, second and third insulating layers 3, 5,
7, and since there is a limit to how small each layer thickness can be to ensure the necessary insulation, there is a limit to how small the gap length can be. For example, when each insulator layer 3, 5, 7 is formed with a SiO ₂ film, in order to eliminate pinholes in each film, the thickness must be 0.5 μm or more, and the integrity of the insulation and the height difference due to the coil (e.g.
0.7 μm for each membrane from the cover of 1 μm), so the gap length is 2.1 μm or more.

In thin-film magnetic heads, it is necessary to increase the number of turns in the coil in order to increase the generated magnetic field, prevent heat generation, and enable driving with minute currents.
In the magnetic head shown in the figure, the gap length inevitably increases in proportion to the multilayered coils. For this reason, a portion of the insulating layer in the front gap portion of the magnetic head is removed or omitted to reduce the layer thickness in that portion. Figures 3 and 4
The figure shows, in cross section, different examples of magnetic heads that have been devised for this purpose. In Figure 3, all of the insulator layer except for the area under the coil has been removed using the coil 4 as a mask, and in Figure 4, only the insulator layer in the gap area (front and rear sides) has been removed using photo-etching technology. After that, the upper core 8 is formed by providing a spacer 9 for defining the gap length. however,
The former has a large step between the lower core and the coil plane, and there is a high possibility that the R part in the figure will be incompletely covered when the insulating layer is formed to wrap around them. There were drawbacks such as a decrease in film thickness and a risk of magnetic flux leakage occurring at the stepped portion S between the core and the surface of the insulator layer.

The present invention aims to eliminate this drawback and provide a magnetic head with a good gap, which comprises a lower core and a plurality of insulating layers including coils formed on the lower core. In order to reduce or eliminate the step difference between the magnetic head and the magnetic head, the present invention aims to provide a magnetic head in which a second lower core is disposed on a lower core facing the upper core.

Next, the present invention will be explained based on illustrated embodiments.
FIG. 5 is a plan view of one embodiment, FIG. 6 is a sectional view taken along the line A-A' in FIG. 5, and FIG. 7 is a front view seen from the direction of arrow B in FIG. However, the protective member above the upper core is omitted in FIGS. 5 and 6. In this embodiment, 20 magnetic heads are provided on one substrate, and each magnetic head has a constant track width T (for example, 80μ) and is aligned at a constant track pitch U (for example, 165μ). A monitor pattern 40 for defining the gap depth V is provided on each side of the magnetic head at both ends, and the tape contact surface 41 is polished using the monitor pattern. Further, in the portion 42 removed by this polishing, an electrode introducing portion 43 for forming a second lower core to be described later is provided. Since each magnetic head is formed symmetrically, one magnetic head will be described in detail below as a representative.

In each figure, 10 is a base, 11 is a lower core attached to this base, 12 is a second lower core arranged on this lower core, 13, 14, 1
Reference numeral 5 indicates first, second, and third insulating layers; reference numerals 16 and 17 indicate first and second coil portions; reference numeral 18 indicates a spacer constituting a front gap portion; and reference numeral 19 indicates an upper core. Both the lower core 11 and the second lower core 12 are made of highly conductive permalloy, and the insulating layers 13, 14, 15 and each coil portion are made of silica (SiO ₂ ) and aluminum (Al), respectively. ing.

The second core portion 12 includes the first to third insulator layers 1
It is formed by electrodeposition on the lower core 11 to a thickness corresponding to the total thickness of these insulator layers using 3, 14, and 15 as masks, and the surface of the second lower core 12 and the third No substantial step is formed between the surface of the portion of the insulating layer 15 that does not include the coil portion below. Therefore, the upper core 19 that is commonly formed on the second lower core 12 and the third insulating layer 15 with the spacer 18 in between is connected to the coil portions 16 and 17 by the insulating layers 14 and 15. The upper core itself is sufficiently insulated, and unlike the conventional example shown in FIG. 4, which does not have a stepped portion S, the thickness of the upper core itself does not become extremely thin, and magnetic flux leakage can be prevented. .

The second lower core material is attached onto the monitor pattern 40 at the same time as the second lower core is molded, and a plurality of second lower core materials are attached to the monitor pattern 40 to determine the depth V of the magnetic head (the distance from the tape contact surface of the gap to the end of the gap). Comb teeth with different depths are formed.
As can be seen from the front view of FIG. 7, the depth V can be estimated based on the number of comb teeth in the monitor pattern. Instead of this method, as shown by the imaginary lines in FIG. 5, a monitor pattern 44 as shown in the figure is molded at the same time as the coil portion is molded, and a notch edge is formed on a portion 45 of the pattern at a position that determines the depth. Alternatively, the tape contact surface may be detected by a change in resistance value between the patterns 44a and 44b. In addition, in FIG. 7, 50 is a protective layer;
1 is a mounting material layer, 52 is a shield and a protective material, and these protective members are omitted from illustration in other drawings.

Next, the procedure for manufacturing such a magnetic head will be explained according to the process diagram of FIG. 8. On the surface of a photoceram base 80 with a thickness of about 1 mm, a thin film 81 made of a soft magnetic material (permalloy) with good conductivity is attached to a thickness of about 3 to 5 μm to serve as a lower core. (FIG. 8a) Next, on this thin film 81, a thin film 82 (film thickness of about 1.5 μm) made of an insulator, such as SiO ₂ , is attached (film thickness is about 1.5 μm), and then this A pattern 83 made of aluminum that will become the first coil portion is attached on the thin film (FIG. 8c),
Next, a thin film 84 serving as a second insulating film, a pattern 85 serving as a second coil portion, and a thin film 86 serving as a third insulating film are sequentially applied in the same manner (FIG. 8d).
Note that after the thin film 84 is attached, the thin film on the pattern 83a is removed, and when the pattern 85 is formed, a short circuit is made to the pattern 83a on the thin film 82.

After the coil portion is formed on the base 80 in this manner, thin films 82, 84, and 86 are punched out using photolithography to form the front and back gaps that sandwich the coil portion, and the portions that will form the monitor pattern. At the same time, an electrode introducing hole 43 is formed (FIG. 8e). Note that 87 is a punched hole.
Silica (SiO ₂ ) is used as the insulating layer as in this example.
When using a mixed solution of HF and NH ₄ F, _unnecessary parts can be removed by using a mixed solution of HF and NH ₄ F. be able to). Next, a thin film 88 made of permalloy and having a thickness of about 4.5 μm, which will become the second lower core, is attached by electrodeposition onto the thin film 81, which will become the lower core, on this punched part using the next bath (Fig. 8). f). The solution is
_NiSO4・_6H2O , _NiCl4・_6H2O , _FeSO4・_7H2O ,
H ₂ BO ₃ , saccharin sodium, and sodium laurate are 300, 25, 5-20, 15, 0.5, respectively.
0.2 [g/], and the anode is 78% Ni/Fe.

Thereafter, a thin film (made of silica, for example) to serve as a spacer is attached by sputtering, vapor deposition, etc. to a thickness of about 0.7 μm, for example. At this time, a mask may be provided on the part corresponding to the back gap to prevent the thin film from adhering to that part, but in this embodiment, in order to simplify the work, this thin film is applied over the entire surface. Next, a thin film of a soft magnetic material (for example, permalloy) is applied by sputtering, vapor deposition, etc. to a thickness of about 3 to 5 μm, and this is patterned using photolithography to form an upper core.
In order to form the notch 45 used for monitoring the gear depth, it is sufficient to use an etchant that selectively removes the pattern ₄₄ made of _aluminum . The pattern appearing in the notch 45 is removed in a specific manner.

FIG. 9 shows a sectional view corresponding to FIG. 6 of another embodiment, and the same functional elements in the figure are given the same number. These are the first to third insulator layers 13',
14' and 15' are molded by solidifying water glass. This makes it possible to eliminate all the steps except for the through holes for connecting the first and second coil sections, and it is possible to almost completely eliminate disconnections, dielectric breakdown, magnetic flux leakage, etc. at the step sections. Furthermore, film formation and patterning can always be performed on a flat surface, and film characteristics and processes can be stabilized.

FIGS. 10 and 11 are views corresponding to FIGS. 6 and 7 of still another embodiment, and in each figure, the same figure number indicates the same functional element. This makes the width W in the track width direction of the through hole 20 for attaching the second lower core 12 match the track width,
And the amount (thin film) of the second lower core installed in this through hole is determined by the total thickness Y of the first to third insulator layers.
The track width is regulated by a through hole in the insulating layer. This allows accurate track width control and eliminates the need for fine patterning of the upper core.

[Brief explanation of drawings]

FIG. 1 is a partial longitudinal sectional view of a conventional thin film magnetic head. Figures 2a, b, and c are partial plan views showing the procedure for forming the coil portion and the upper core. 3 and 4 are partial longitudinal sectional views of conventional examples, respectively. 5, 6, and 7 are a central sectional view, a partial plan view, and a front view of the magnetic head of the present invention. FIGS. 8a to 8f show manufacturing procedure diagrams of the magnetic head,
a, b, d, e, f are cross-sectional views, and c is a partial plan view. FIG. 9 is a sectional view of another embodiment, and FIGS. 10 and 11 are sectional views and front views of still other embodiments. Explanation of main drawing numbers, 11... lower core, 13, 1
4, 15...first, second, third insulator layers (insulator layers), 12...second lower core, 19...upper core.

Claims (1)

[Claims] 1. A flat lower core is provided on a base, and a coil is formed on the lower core, an insulator layer that encloses the coil and is formed except for the front and back gap components, and the insulator layer is not formed. a second section attached to the front and back gap components;
a lower core, and a spacer forming a gap on the insulator layer and the second lower core,
A magnetic head characterized in that an upper core is disposed on the spacer.