JPH0416841B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic head, and provides a method for manufacturing a magnetic head suitable for obtaining narrow track ferrite magnetic heads used in video tape recorders, for example. .

The track width of magnetic heads used in recent video tape recorders has been reduced to enable high-density recording and reproduction, and has been realized, for example, on the order of 30 .mu.m. However, it is becoming difficult to ensure accuracy when machining track widths, and the use of photoetching has been proposed as a solution to this problem. For example, as shown in FIG. 1a, the track width is machined with high accuracy in advance by photo etching, and then, as shown in FIG. 1b, the missing part of the etching is largely removed by machining. As shown in FIG. 1c, a winding groove 1 is formed on one of the pair of ferrite blocks that have been processed for track width in this way, and then both blocks are connected through a gap glass layer. After joining together, cut into individual chip cores.

However, conventional magnetic head manufacturing methods that include such steps have the following drawbacks.

(1) In order to process the groove shown in Figure 1b after the track width machining by etching shown in Figure 1a, it is necessary to cut grooves with high precision on both sides of the track part, but the edges of the groove may cause chipping. Alignment is difficult because the position of the groove cannot be measured accurately.

(2) It is necessary to align each bar for groove machining, which is inefficient.

(3) If glass is molded into the track width regulating groove at the same time when the blocks are joined, there is a risk that the gap glass layer will change in quality due to the influence of the molded glass and the performance will deteriorate.

In view of the above-mentioned drawbacks of the conventional magnetic head manufacturing method, the inventors proposed a method in which grooves were previously formed in the head block by machining and glass was molded in the head block in Japanese Patent Application No. 55-48352 (Japanese Unexamined Patent Publication No. 56-145518). Afterwards, we proposed a method for manufacturing magnetic heads in which track width regulating grooves are formed by etching.
That is, this method uses a rectangular bar-shaped ferrite core block and performs track width processing on the corner surface of one longitudinal side of the core block by machining and etching. The present invention is a further improvement on the above-mentioned earlier application, in that the head is fabricated using a substantially square or circular flat plate-shaped ferromagnetic material.
The accuracy when machining track width regulating grooves by etching depends on the pattern formation accuracy of the etching master, but in order to form the mask pattern with high accuracy, it is necessary to apply the photoresist to a uniform thickness. is important. When a photoresist is spin-coated on the square bar-shaped core block surface of the conventional example as is generally done,
The film thickness increases at the edges of the surface, that is, on each side, and the larger the aspect ratio of the core block surface, the more uneven the film thickness becomes. Therefore, the photoresist can be more uniformly applied to a flat material with a wider plane.
Furthermore, compared to printing a pattern on a single rectangular bar-shaped core block, it is clear that it is more efficient to print the pattern on multiple heads formed on a flat plate. This makes it possible to take full advantage of the advantages of photoetching, which allows printing of patterns.

Embodiments of the present invention will be described below with reference to the drawings. Figures 2a-f show a first embodiment of the invention.

First, as shown in Figure 2a, a core plate 2 (25
Grooves 3 are formed on the gap forming surface of mm□/1 mm thickness by machining means such as dicing at intervals narrower than the thickness of the completed head chip. In this example, the track width is 20 μm, so the spacing between the grooves 3 is
30 μm, depth is 200 μm. Next, this groove is molded with a non-magnetic material such as glass, and the surface is polished to a mirror finish.

Thereafter, a photoresist mask 4 for forming track width regulating grooves by electrolytic etching is formed on the surface provided with the gap. The interval between the windows in the track portion of the photoresist mask 4 is 26 μm, taking into account the amount of undercut during etching (the second
Figure b).

Using this photoresist mask 4, a groove with a depth of 3 μm is formed by electrolytic etching. The electrolytic conditions were as follows: using an electrolytic solution of phosphoric acid: sulfuric acid: glycerin = 1:1:1, an applied voltage of 8 V and about 1 μm/min.

In addition to electrolytic etching, track width regulating grooves can be formed with high precision by performing ion etching or sputter etching using a thin film of titanium or chromium, which has a lower sputter rate than ferrite, as a mask. Furthermore, grooves can be formed with high precision on metal magnetic materials such as sendust by electrolytic etching, sputter etching, ion etching, etc.

FIG. 2c shows an enlarged view of the groove section after etching. As shown in the figure, a track width regulating groove 5 is formed by etching in the lower part of the window of the photoresist mask 4. As shown in FIG.

Next, after removing the photoresist mask 4 for etching, a winding groove 1 is formed on the gap forming surface by machining such as dicing so that a winding window is formed on at least one side of the head chip. Figure 2 d).

Next, glass for regulating the gap length is formed on the gap forming surface by sputtering, and the core blocks 6 and 6' are cut along the broken lines shown in Fig. 2d, and then heated and bonded to the opposing core block (Fig. 2e). . By further cutting along the broken line in FIG. 2e, the head chip shown in FIG. 2f is obtained.

In the above-mentioned embodiments of the present invention, the magnetic head was fabricated from a square plate, but in view of the photoresist coating conditions, even better results can be obtained by using a disk.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3a to 3c. As in the first embodiment, Mn−
Grooves are formed on the gap forming surface of a ferromagnetic plate such as Zn ferrite, and after molding with a non-magnetic material such as glass, the surface is ground and polished to a mirror finish.

Next, a first mask 7 for track regulation and a second mask 8 for deep etching made of independently removable material are formed by means such as photo-application (FIG. 3a).

The material of this mask is, for example, a first mask 7 made of chromium for sputter etching.
and a second mask 8 made of photoresist for electrolytic etching. In this combination, the first mask 7 made of chromium is insoluble in the photoresist stripping agent, so that the two types of masks can be etched independently. That is, after etching the first groove 9 using a second mask 8 made of a second photoresist, the photoresist is removed with a remover, and then the track width is etched using a first mask 7 made of chrome. A regulating groove is formed by sputter etching (FIG. 2b).

Thereafter, the first mask 7 is removed and winding grooves are formed in the same manner as in the first embodiment, and then opposing core blocks are heat-bonded via a gap length regulating material and cut into head chips.

Next, a third embodiment of the present invention will be described with reference to FIGS. 4a and 4b.

Similar to the first embodiment, grooves are formed on the gap forming surface of a ferromagnetic plate such as Ni--Zn ferrite, and after molding with a non-magnetic material such as glass, the surface is ground and polished to a mirror surface. Next, track width regulating grooves are formed by photographing, winding grooves are processed, and then the core block is cut into core blocks. This is heat bonded to the head half that will become the slider via a gap regulating material (FIG. 4a).

After cutting the air bearing surface into grooves, it is cut into head chips to obtain a magnetic head for a magnetic disk (FIG. 4b). Note that 10 in Figure 4b is the slider, 1
1 is the core.

As described above, the following advantages can be obtained by forming track width regulating grooves on a square or circular plate by combining machining and photoetching.

1. Machining accuracy can be improved several times compared to machining accuracy of ±2μm.

2. Preliminary groove machining by machining can prevent a decrease in accuracy when large grooves are formed by etching alone.

3. Since the photoresist is applied to a square or circular plate, it is easy to make the resist thickness uniform and the precision of the mask can be achieved.

4. Most of the machining is done on the plate, making it easy to handle, and patterns can be printed on several core blocks at a time, greatly improving efficiency in the refining process.

Furthermore, according to the method of the second embodiment, since most of the etching is done when forming the first groove, only a small amount of etching is required for the track width regulating groove.
Furthermore, track width accuracy can be improved.

Furthermore, compared to the conventional method of forming grooves after etching, this method is superior in the following points.

1. Aligning a photomask with a groove formed by machining is easier and more accurate than aligning a machined groove with a convex portion of an etched ferrite block.

2. When bonding ferrite with glass, the reaction at the interface between the glass and ferrite depends on the bonding temperature, and the higher the temperature, the thicker the reaction layer becomes.
Therefore, when bonding parts that require extremely high dimensional accuracy, such as magnetic gaps whose length is controlled by the thickness of the glass, it is necessary to lower the bonding temperature to minimize the thickness of the reaction layer on the gap surface. is important. On the other hand, when bonding glass in a narrow area, in order to spread the glass to every corner, it is necessary to heat the glass to a high temperature until it becomes sufficiently fluid.

The above requirements regarding the glass bonding temperature are contradictory, so if you try to fill the groove with glass at the same time when bonding the gap of the opposing core block after forming a groove for regulating the track width in the ferrite, both temperature conditions will be met at the same time. That is difficult. In other words, in the conventional method of forming a groove after etching and simultaneously filling the entire groove with mold glass when gap-joining opposing core blocks, the mold glass has a viscosity that is sufficiently fluid to spread the glass to every corner of the groove. It is necessary to heat the product to a high temperature (approximately 700℃). Therefore, at the same time, the temperature of the gap portion rises too much, and the gap glass layer may change in quality, leading to performance deterioration.

However, according to the present invention, the glass that fills the grooves formed in the ferrite to roughly regulate the track width is poured in advance, so when bonding the gap, it is possible to precisely control the track width near the gap while bonding the opposing core block. It is only necessary to fill in the small groove (track width regulating groove) formed by etching to regulate the track width. When bonding opposing molded glass filled in the processed grooves, even if there is some unevenness on the glass surface, the size of the unevenness is about 2 to 3 μm. It is not necessary to lower the viscosity of the glass as high as when pouring it (approximately 10 μm);
By raising the temperature to a certain level, the molded glass becomes semi-fluid, and its surface tension fills the recesses in each glass and joins them together. Since the small grooves formed by etching at this time are approximately 3 μm in diameter, they are simultaneously filled in by the surface tension of the molded glass as it becomes semi-fluid.

Therefore, compared to the conventional case of pouring new glass into the processed groove, gap adhesion can be performed at a low temperature in a semi-fluid state, so reaction at the interface between ferrite and glass can be suppressed. Therefore, there is less possibility that the gap glass layer will change in quality and its performance will deteriorate.

[Brief explanation of drawings]

1A to 1C are diagrams for explaining a conventional method of manufacturing a magnetic head, FIGS. 2A to 2F are diagrams for explaining a method of manufacturing a magnetic head according to an embodiment of the present invention, and FIG. 4c are diagrams for explaining a method of manufacturing a magnetic head in another embodiment of the present invention, and FIGS. 4a and 4b are diagrams for explaining still another embodiment of the present invention. 2... Core plate, 3, 9... Groove, 4, 7,
8...Mask, 5...Track width regulation groove, 6,
6'...Core block, 10...Slider, 11
……core.

Claims (1)

[Claims] 1. Forming grooves at intervals wider than the track width on a substantially square or circular plate made of ferromagnetic material, and polishing the surface after molding a non-magnetic material into the grooves. 1. A method of manufacturing a magnetic head, comprising the steps of: forming track width regulating grooves by photoetching. 2. The method of manufacturing a magnetic head according to claim 1, wherein the track width regulating groove is formed by etching in two stages, deep and shallow.