JPH01133212A - Thin film magnetic head and its production - Google Patents

Abstract

PURPOSE:To attain low cost by constituting an area opposite to a gap so as to be smaller than the section of a core substantially orthogonal to the magnetic flux of a magnetic path forming circuit, providing a slant face in a coil side face to the gap and contracting the magnetic flux. CONSTITUTION:When the area opposite to the gap of the cores 1, 2 is defined to be S1 and the sectional area of the core part of a magnetic forming circuit orthogonal with the magnetic flux of the gap opposite part to be S2, S1<S2 is obtained. When the magnetic flux excited by the coil 4 has not convex part 11', a magnetic flux convergence substantially corresponding to Cw'/Cw is attained from the rear core part 12 of a core width Cw to the front core part 11 of a core width Cw'. When it has the convex part 11', the inclination 11'd of the gap 11'e0 of the convex part is spread to a lower core spreading core part 13a, so that the magnetic flux flows correspondingly to the lower core spreading angle theta2 and the inclination angle theta1 of the slant face. Thereby, the complete magnetic flux contraction is realized in the vicinity of the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head used in a magnetic recording/reproducing device such as a VTR, and particularly to a magnetic head that has long life and high 1g reliability. This article relates to a thin film magnetic head that can be used.

[Conventional technology]

In recent years, magnetic recording density has improved dramatically, and increasing the coercive force of tape is becoming the mainstream technology. Therefore,
The development of heads that use metal materials with high saturation magnetic flux as core materials is remarkable. Particularly in the case of heads used at high frequencies, the mainstream technology is to form them with thin films, and the thin film process is seen as promising in terms of performance and production. On the other hand, thin-film heads are structurally prone to core saturation during recording, requiring structural improvements including the volume of the core. A core structure that takes this point into consideration is described in, for example, Japanese Patent Laid-Open No. 74810/1983. This is to achieve a magnetic flux restriction effect within the plane of the thin core, and as shown in Figure 12, the core width decreases steadily from the rear end of the core 20 toward the tip, and the magnetic flux increases toward the tip. It has a structure that allows it to be squeezed. In addition, the head tip gap surface portion 22 is small because it is necessary to keep the track width constant. It is set to a value larger than zero.As an example of expecting a magnetic flux throttling effect depending on the film thickness,
There is No. 751. As shown in FIG. 13, this has a structure in which the lower core has a two-layer structure of a core 32a and a core 32, and the magnetic flux is narrowed down at the tip of the head.

[Problem to be solved by the invention]

However, in the former case, magnetic flux can be focused in the range where the core cross-sectional area decreases toward the head tip, but if the gap depth is increased considering head wear life, the track width remains constant within the gap depth range. Therefore, no magnetic flux focusing effect can be expected in this range. The situation is similar for the latter case, which aims to achieve a focusing effect based on the film thickness, and the focusing effect at the tip where the film thickness is constant cannot be determined. Therefore, with these heads, it is possible to drive the core at the tip of the gap to saturation only within a gap depth range smaller than the film thickness at the zero gap depth point of the core.For these reasons, the use of conventional thin film magnetic heads is It was limited to systems with little concern about sliding wear.

SUMMARY OF THE INVENTION An object of the present invention is to provide a four-film magnetic head which achieves sufficient magnetic flux restriction in the vicinity of the gap and which makes it possible to obtain long-life and highly reliable recording and reproducing characteristics.

[Means to solve the problem]

The above purpose is to prevent at least a part of the protrusion, which is formed so that the cross-sectional area of the core near the gap surface of the gap opposing part gradually increases as the core moves away from the gap surface from the gap surface, from the tape surface of the core. This is achieved by making it overlap with the widening part of the rear part when viewed from the moving surface. In particular, the protrusion shape is formed by etching a core made of a thin film at least twice so that there is no part parallel to the gap surface, and the shape of the sliding surface is approximately the track width from the gap material surface to a certain depth. Thereafter, this object is achieved by forming the gap into a shape that becomes wider as it moves away from the surface of the material.

[Effect]

In the present invention, the magnetic flux excited by the coil during recording is narrowed from the rear part of the lower core to the tape sliding side, which is the tip, by an amount corresponding to the change in core width, and reaches the tip, resulting in a flow with a constant magnetic flux density. On the other hand, a part of the magnetic flux of the 91 core flows into the convex portion located in the middle of the aperture, and this amount of magnetic flux is added compared to the conventional case where the convex portion does not overlap with the lower core aperture. Furthermore, this total magnetic flux flows through the truncated quadrangular pyramid of the convex part to the gap surface, and at that time, magnetic flux is focused according to the shape of the pyramid, flows to the upper core, reaches the rear of the lower core, passes through the upper and lower core joints, and enters the magnetic core. Go around. Therefore, the maximum value of the magnetic flux density in the magnetic path is at the gap portion, and the gap depth corresponding to the focusing ratio is ensured without impairing the recording ability.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of essential parts showing the thin film head of the present invention. The third factor is a front view of the upper and lower cores seen from the tape sliding surface. FIG. 1 is a plan view of the lower core before processing. FIG. 4 is a sectional view taken along line A-A'K in FIG. 1. In the figure, 1 and 2 are made of magnetic films, and the lower core is formed so that the tip has a constant width and the width gradually increases toward the rear.
The upper core is shown, the two cores forming a gap 5. As shown in FIG. 1, the lower core 1 has a front core part 11 having a core width U larger than the track width when viewed in plan, a rear core part 12 having a core width y larger than the core @y, and a gap between the front core part 11. It consists of a core part 13 whose core width is widened at an angle #2 (lower core spread angle) from the zero depth position tll A + toward the rear core part 12.The front core part 111C protrudes upward and the core thickness A rectangular gap surface 11e with a core width -r that is the same or approximately the same as the track width, and an inclined surface 114 formed by extending from the gap surface at an angle of 11 (inclination angle) in all directions.
A convex portion (truncated quadrangular pyramid) 11 having a diameter of 11j to 11j is formed. This does not have to be a truncated square pyramid as long as it is not close to the gap plane (and the volume of the core is ).
', i.e., the slope rfJ11 located at the end of the gap.
'd is as shown (from gap depth zero position L1 to core @1
In other words, the core width of the lower core 1 is wide by the five-direction width dimension X (it is expanded so as to overlap the core portion 134). Inclined surface 1 formed by forming a gap surface
A convex portion 12 is formed to grow 2'α to 12'd. The upper core 2 is formed similarly to the lower core 1. 4 is a coil, and 5 is an insulating layer.

Here, when the area of the gap-opposing part of the parts 11 and 2 is 81, and the cross-sectional area of the core part of the magnetic formation circuit in the direction perpendicular to the magnetic flux of the gap-opposing part is 82, it is formed so that the relationship St(Sg) is satisfied. It is.

Next, the magnetic flux focusing effect within the core plane will be explained.

When the convex part 11 is not present, the magnetic flux excited by the coil 4 flows from the rear core part 12 of the core @~ to the front core part 11 of the core width ', and the magnetic flux is concentrated in the front core part 11 approximately equivalent to ~'/CW K. is planned. On the other hand, when there is a convex part 11', the gap of the convex part 1t'eo (gap depth zero position)
Since the inclined surface 11'd extends to the lower core spread core portion 13cL, magnetic flux flows in corresponding to the lower core spread angle #2 and the slope angle #1. Regarding the position of the front core part 11, as shown in Figure 81, the gap end part 21. The slope of the lower core expansion start part 12 and the front core protrusion 11 is 0
(Zero)K is iδ, and the position of 15 with respect to Bu2 is X
(The rear is +). When 12 is located behind M, the smallest cross-sectional area in a plane perpendicular to the substrate is between 22 and Ls and is indicated by Cwxj (d is the film thickness FT-h). On the other hand, the cross-sectional area at 11 is -xd+(Tw+Cw')x''-.

In the case where the front core portion 11 overlaps the core widening portion, that is, 1. If z is in front of c, the minimum cross-sectional area is 22
The position of the translation to the busy position ~ xd 10 is indicated by hx. Cw)xCw
> Tw, so the second term is positive. Therefore 12 is 2
Thicker than the minimum surface area CWxd when coming after s (
Become.

When 22 overlaps 11, that is, when X=O, the minimum cross-section selection is Cw X cl + (Tw+Cw') at the position of Ll.
! It becomes A-, which can be said to be the best position. As mentioned above, 12
It is effective to have a structure in which the protruding portion of the front core portion 11 overlaps with the widening portion of the core. Xl
If is after 22, all (same).

The convex part of the front part 11 of the lower core 1 is removed (the cross-sectional area in the sliding direction of the front part 11 is Ss, and the lower core spreading start tI of the front part 11 is 5s (5s when the cross-sectional area on sj12Ii1 is 84). It is formed as follows.

Figure 5 K Tw = 5Qμs, Gd = 20%as
, FT = 25 μm, h = 5 μm, #+=50
．． The head performance data when #z=45°KLXt- is changed is shown. The horizontal axis is the value of X, and the vertical axis is the experimental result when the recording current value and head output are taken. In the same figure,
When X exceeds 23 μm, there is little change in both the reproduction output and the recording current, but when O<X<3 μm, the output decreases rapidly and the recording current increases. At X0, the optimum value of the recording current is not detected and the output settles at a low level regardless of the increase in current. This result shows that if X > 3, there is no problem with the recording performance, if X < 3 or later, deterioration begins, and if X < O, it is not practical. The conventional head corresponds to x OK. However, even in this case, it goes without saying that recording performance can be improved by reducing the gap depth Qd. The experimental conditions were: tape holding force = 650, Oersted running system VH8VTR, circumference mantissa 1z (wavelength 5
．． 8 μm] Head gap depth is 30 μm.

FIGS. 6 to 8 are diagrams showing other embodiments of the protrusion of the front core of the thin film magnetic head of the present invention.

6 is a front view of the head sliding surface, FIG. 7 is a sectional view of the head in the magnetic path length direction, and FIG. 8 is a perspective view of the shape of the lower core, where 6 is a substrate, 1 is a lower core, and 2 is a sectional view of the head in the magnetic path length direction. 5a and 5b are non-magnetic insulating materials; 34 is a gap material; 2
is an upper core, 8 is a protective film, 7 is a protective plate, and 4 is a coil.

In FIG. 6, the shape of the sliding surface of the upper core 2 is a fan shape that widens in a straight line with an angle l to the insulating material 5a as it leaves the surface of the gap material 34, and the maximum width L1 of the upper core width. angle! The insulating material made of 5a is formed so that the relationship with the width L2 of the upper surface of the through hole is L1≦L2. In addition, the shape of the sliding surface of the lower core 1 is
As shown in the perspective view in the figure, at least the gap forming portion is formed in two stages as follows. That is, from FIGS. 6 and 8, the angle α1 (first angle) is from the gap material 34 to a certain depth t, the angle α2 (third angle) from tl to t2, and the initial taper angle thereafter. r (second angle) is
α1〉α2)0. The lower core width is formed to increase as it moves away from the surface of the gap material 54 so as to satisfy the relationship α2cr, α1er.

In other words, the core cross section MR8rβ8 near the gap in the front portion of the lower core 1 is formed so as to become larger as the distance from the gap surface increases.

2, the track width is narrowed by making the t2 portion of the lower core non-parallel to the gap surface. The edges of the upper and lower cores on the side opposite to the gap material 34 are formed so as to be non-parallel to the gap surface.

By forming the upper core 2 and the lower core 1 into such a shape, the magnetic flux can be effectively narrowed in the thickness direction of the core. In addition, because the gap depth is increased (if the lower core thickness is increased for the purpose of increasing the thickness, as will be explained later in the manufacturing method), the width is defined within a certain depth of the steep taper angle α1. High precision can be easily achieved. Moreover, the track l is steep at angle α1! The part focused on Tw (
The generation of a pseudo gap can also be suppressed by connecting the part 1) with the part that widens at the initial angle r by a part tilted non-parallel to the gap plane at an angle tt2 (part t2). .

91st f! J shows another embodiment of the thin film magnetic head according to the present invention, and FIG. 9 is a cross-sectional view of the head corresponding to FIG. However, the inside of the protrusion may be filled with only non-magnetic insulating material and the coil conductor may be formed in the same manner as in the first embodiment.

According to this embodiment, in addition to the effects similar to those of the previous embodiment, there are the following effects.

Since the angle α1 is steep, leakage of magnetic flux between the upper and lower cores at this portion can be reduced, and head efficiency can be improved.

In addition, when embedding a coil in a protrusion, a steep angle α1
By making use of the two-stage taper with a gentle angle α2, the space in which the coil can be formed can be expanded, and there are effects such as lowering the resistance of the coil winding or increasing the number of turns.

FIG. 10 is a front view of the head sliding surface IJh showing still another embodiment of the ?V film magnetic head according to the present invention.

In the figure, the lower core 1 is sunk into the substrate 6 except for the gap forming part and the rear connecting part protrusion in the previous embodiment, and is formed to have the minimum thickness of the non-magnetic insulating material sbl in FIG.

As an effect unique to this embodiment, non-magnetic P! Since the thickness of the shielding material 5b is small and it only needs to be formed in a small portion, it is effective in shortening the process, improving precision by reducing warpage of the substrate, and preventing peeling of the film due to heat treatment in a post-process.

Next, a manufacturing method of the embodiment shown in FIGS. 6 to 8 will be explained.

FIG. 11 is a process diagram illustrating an example of the manufacturing method of the embodiment (FIG. 10(b)).

Hereinafter, each step 8(a) to (ri) will be explained in order.

(cL) A hole in the shape of a tie or lower core for embedding the 'F section cocoa is formed in the substrate 6 by ion milling, guising tooling, or the like. In this processing, the taper angle is set with a margin that does not adversely affect the magnetic properties of the magnetic film in the next step.

(b) Form the magnetic layer d1' for the lower core by sputtering.

(C) During ion milling, the magnetic film is patterned into a lower core shape to form the lower core 1.

(d) Non-magnetic insulating material 5b (for example 5i02.Id
hOs, etc.) is formed by sputtering, vapor deposition, etc., and then polished and planarized. In this case, polishing may be stopped before the substrate surface is exposed.

te) Lower core 1, non-magnetic I/I! The edge material 5b and the substrate 6 are etched to control the track width and to form protrusions on the front and rear parts to create the shape shown in FIG. 8 or 4. Etching at this time uses ion milling and etching at an appropriate beam incidence angle, resulting in taper angles α1 and α shown in Figures 6 and 8.
Two parts can be formed at the same time. For example, according to the inventor's experiments, when a Co-Nb-Zr film was used as the magnetic film and the beam incidence angle was set at 55°, α1 and α2 could be set to approximately 80° and 45°, respectively. .

After this protrusion formation step, the core width is determined in the previous step so that there is no part parallel to the gap surface, but by selecting a material with a faster etching rate than the magnetic film for the non-magnetic material 5b, this core Width specifications can be made more relaxed. For example, the core material is Co-Nb-Zr g ,
When using the non-magnetic material 5b KSiOz film, the above-mentioned oblique etching speed ratio (Sing-, /Co-Nb-Z
r) is about 13, which makes it difficult for parallel parts to form.

<r> After forming the nonmagnetic insulating layer, the coil, and the nonmagnetic insulating layer again, the gap forming surface 3 is polished.If the polishing at this time is within the thickness of t'1 in (e), Since it can be stopped anywhere, it is suitable for mass production.

(ω In the case of a two-layer coil, a second coil and a non-magnetic insulating layer 5a are formed, and through holes are made in the gap forming surface 3 and the 9-acoa connecting portion 12.

(h) Form the gap material 34 made of a non-magnetic material.

(i) A magnetic film is formed by sputtering, buttered by ion milling, and the upper core 2 is placed in the tapered part of the front through hole raised in the nonmagnetic insulating layer 58.
form. This etching is performed using a photoresist mask material that has undergone a predetermined post-baking process at an appropriate beam incidence angle to curve the edges, reduce the contour effect, and improve the step coverage of the protective film 8. be able to.

Through the steps described above, a head having the cross-sectional shape of the embodiment described above can be manufactured.

In this process, the shape of the sliding surface becomes different from the depth trap of the groove or hole shown in the example. Also, the other one of the last example (Fig. 10 (cL)) , can be manufactured by changing the process shown in FIG. 11 as follows.

That is, after (b), the gap forming surface 3 is made flat by JIIK and the track width is controlled first ((e
). Next, the lower core portion parallel to the gap plane is removed by etching again. Next, a non-magnetic insulating material is formed and flattened by polishing. This completes the process corresponding to (f), and the same goes for the rest.

As described above with reference to the embodiments, one of the features of the present invention is that the shape of the base when forming the magnetic film can be set to have a pest shape with magnetic properties.

Further, the above-mentioned thin film magnetic head is effective when installed in a device that partially overwrites adjacent tracks.

〔Effect of the invention〕

As explained above, according to the present invention, by using a thick magnetic film, it is possible to achieve sufficient magnetic flux restriction 1 in the vicinity of the gap and to achieve high accuracy in track width. It can simultaneously satisfy the conflicting demands of security and the resulting decline in recording performance, and the thin-film head, which was conventionally used only in systems where wear resistance was not a concern, can now be applied to tape-sliding type systems such as VTRs. Therefore, it goes without saying that these images will have higher image quality, but the mass production process can also be expected to be effective, and this will also have the effect of contributing to lower costs.

[Brief explanation of the drawing]

Fig. 8g1 is a plan view schematically showing the lower core of the thin film magnetic head of the present invention, Fig. 2 is a sectional view of essential parts of the thin film magnetic head of the present invention, Fig. 3 is a front view thereof, and Fig. 4 is a plan view schematically showing the lower core of the thin film magnetic head of the present invention. A- in Figure 1
A KG sectional view, FIG. 5 is a characteristic diagram for explaining the present invention, flEb to FIG. 8 are detailed explanatory views of the present invention, FIG. 8 is a perspective view showing the shape of the lower core, and FIG. 9 is a view showing another embodiment of the present invention.
Figure 0 is a front view of the head sliding surface of another embodiment of the present invention.
FIG. 11 is a process diagram for explaining the method of manufacturing a thin film head of the present invention, and FIGS. 12 and 13 are a plan view and a cross-sectional view of a main part showing the top surface of a core for explaining a conventional magnetic head. Explanation of symbols 1...Lower core, 2...Upper core, 6...
Gap, 4... Coil, 6... Board,
11...Front core part, 11...Convex part,
12... Rear core part. Broom I Z 2nd 83rd/-m-Lower Core 2-0. Upper sound P core 3-・gien・,fu・th,5″ ■ ゝ、χ−−− 6th Z party 7th 8th ward 9th drawing collection 10th (α) th!I @th tz 'Fi1 n string 73 m -9/

Claims (1)

[Claims] 1. A lower core, a gap material, a coil, an insulating layer,
In a thin film magnetic head (S_2) formed by laminating upper cores, etc., the area (S_1) of the gap opposing portion formed by the opposing upper and lower cores is equal to the magnetic flux of the magnetic path forming circuit formed by the upper and lower cores. 1. A thin film magnetic head characterized in that the cross section of the thin film magnetic head is smaller than the cross section of the substantially orthogonal core, and the coil side side surface of the front part of the core has an inclined surface with respect to the gap, so that the magnetic flux is narrowed. 2. The cross-sectional area (S_4) in the tape sliding direction of the end (l_2) of the end part (l_2) of at least one of the upper and lower cores of the thin-film magnetic head that widens rearward from the front part of the core and begins to widen in a plane is the gap. 2. The thin-film magnetic head according to claim 1, wherein the thin-film magnetic head is larger than a cross-sectional area (S_3) in the tape sliding direction excluding the core protrusion at the forming portion. 3. The thin film according to claim 2, wherein the inclined portion of the lower core protrusion located at the end of the gap at least overlaps the rearward end (l_2) of the lower core that starts to widen in a plane. magnetic head. 4. The lower core gap surface of the gap-opposing part is parallel to the gap depth direction, and the cross-sectional area of the core in the plane parallel to the gap increases as the distance from the gap surface increases, at least in the vicinity of the gap. Claim 1
, 2 or 3. 5. The core cross-sectional shape of the tape sliding surface is characterized in that the tapered shape of the side surface of the core is formed by a steep surface near the gap and two other gentle surfaces (total of 3 surfaces on each side). A thin film magnetic head according to any one of claims 1, 2, 3, or 4. 6. The thin film magnetic head according to claim 5, wherein the core width parallel to the gap of the lower core increases at least as the distance from the gap increases. 7. A magnetic recording and reproducing device equipped with the thin film magnetic head according to any one of claims 1, 2, 3, 4, 5, or 6 and having a function of partially overwriting. 8. In a method for manufacturing a thin film magnetic head in which a lower core, a gap material, a coil, an insulating layer, an upper core, etc. are laminated on a substrate, the lower core is subjected to at least two ion etching steps at different angles. 1. A method for manufacturing a thin film magnetic head, characterized in that the thin film magnetic head is formed using the following steps.