JPS58185022A - Production of magnetic head - Google Patents

Abstract

PURPOSE:To produce easily a magnetic head having high accuracy, by pressure- welding the front gap faces of two core blocks via a nonmagnetic material, cutting the gap faces after welding the side edge part of the gap by a laser and then removing the welded part. CONSTITUTION:Core blocks 5 and 6 have winding grooves 1 and 2 as well as track parts 11 and 12 containing a fixed track width formed by notches 3 and 4. A back gap part 13 is brazed with silver; while the front gap part is pressure- welded via glass films 14 and 15. Then the track parts are laser-welded 16 for every other one at the edge part, and then both ends are laser-welded for all tracks after checking the gap size. Then the blocks 5 and 6 are cut at lines (a1)-(a1'), (a2)-(a2')- to obtain head chips, and then welded with a magnetic head base 17 at lines 18 and 19. The windings are applied to winding windows 1 and 2, and the front part is polished up to positions (b) and (b') to remove the laser welded part 16. In such a way, a magnetic head is produced with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic head, and is particularly useful when applied to manufacturing a magnetic head using a metal magnetic material as a magnetic material.

Hereinafter, as a magnetic head using sendust, which is a magnetic metal material, a video head will first be explained.

Unlike ferrite, sendust is a metal, so there is no glass with a matching coefficient of thermal expansion, so in conventional video and video manufacturing, the core block is joined with silver solder on the back gear and rear surface. Only with
No particular bonding is performed on the front gap surface. Problems caused by this will be explained below along with conventional manufacturing methods.

As shown in Fig. 1, a winding groove 1 for forming a winding window
, 2 and a track portion 11.12 having a constant track width W formed by notches 3, 4. Two core blocks 6.6 are prepared.

A non-magnetic material, usually glass, is provided on the front gap surfaces 9, 10 of the core plates 6, 6 with such a structure by vapor deposition to a thickness of about 0.1+5 μm. Next, as shown in FIG. 2, the core blocks 5 and 6 with the glass vapor deposited films 14 and 15 formed on the front gap surfaces 9 and 1o are
A foil of silver solder 13 with a thickness of several μm is sandwiched between the pack gap surfaces □ 7.8 and abutted against each other, and held with a jig (not shown) so that they can be pressed together. At this time, each track 11. of the core blocks 5, 6.
The accuracy of matching No. 12 is that the deviation in the width W direction is 1 μm.
It is necessary to do the following. During this butting, the front gap surfaces 9, 10 and the pack gap surfaces 7, 8 are flush with each other, whereas the silver solder 13 and the glass vapor deposited film 14.1
Since the thickness of the core block 6.6 is different from that of the core block 6.6 by several μm, the butt state of the core block 6.6 is, for example, extremely exaggerated in FIG. There should be.

The core block 6.6 held in this way is heated to a temperature of several hundred degrees to soften the silver solder 13 and promote the diffusion of the silver solder 13 into the core blocks 5 and 6. Perform the joining in step 6.

At this time, since the core block 6.6 is pressurized by the jig so that the pack gap surfaces 7 and 8 are pressed against each other, the silver solder 13 approaches as it softens, and the silver solder joint between the two core blocks At the time of completion, as shown in FIG. 3, the glass deposited films 14.15 on the front gap surfaces 9 and 1o are in uniform contact over the entire surface, and both deposited films 14.15
A gap portion equal to the total thickness of is formed. In addition,
In a magnetic head made of ferrite material, the notch part 3°4
Although the track portions 11 and 12 are fixed and reinforced by filling them with glass, such reinforcement is not performed in the case of Sendust for the reasons mentioned above.

The core plates 6, 6 which are silver soldered together at the pack gap surfaces 7, 8 in this way are shown in FIG.
a'+ + a2. 7. + --+ an a
The magnetic head shown in FIG. 4 having a thickness of about 200 μm is obtained by cutting with an n-In die.

The above-mentioned magnetic head and its manufacturing method include
There are major problems in terms of accuracy and mass production as described below. That is, as described above, the track portion is not provided with any fixed reinforcing means, and the front gap portion is basically free. For this reason, the joined core block is placed at a predetermined position "+"lTa2'-"2+...+an
Due to the cutting force when cutting at "n", the track portion 11
．． No. 12 easily caused permanent residual displacement of around 1 μm, and both gap length accuracy and track alignment accuracy were significantly deteriorated, resulting in extremely low yield. Furthermore, in order to reduce the working force as much as possible, the cutting efficiency has to be low.

The present invention provides such precision in the video head.
The following are solutions that can solve major problems in mass production all at once.
This will be explained together with an example.

In FIG. 6, only the dimension H of the front gap surface is several hundred μm larger than in the case of FIG. 1, and the other dimensions are exactly the same. Joined with silver solder 13, and at the front gap part, the front gear of the butt track part,
This figure shows the state in which the front end of the tube is laser welded. The shaded area 16 is the laser welded area. In this example,
Welding was performed using a pulse-excited YAG laser, which is suitable for microfabrication and whose irradiation energy can be set accurately and reproducibly. For tracks that have been laser welded, the gap length after welding cannot be optically inspected in the state shown in Figure 6.
It's impossible. However, there is a close correlation between the gap length of the butt track portion where welding was performed and the gear and gap length of the adjacent track portion that was intentionally not welded in this example. By optically measuring the gap length of the missing track portion, it is also possible to accurately determine whether the gap length of the adjacent welded portion is acceptable. After confirming the gap length of the butt track portion in this way, laser welding is performed on the front end of the front gap for the butt track portion that has not been welded, and the entire front gap portion is welded. .

According to the inventor's experience, if the gap length accuracy in the state of the core block is confirmed as described above, it is possible to guarantee the gap length accuracy after cutting into magnetic helad chips. Thus, the core block 6.6 is joined by laser welding the front side ends of the front gaps of all butt track portions, and by silver soldering joining the pack gaps p't. This core block 6.6
, the same a1~”+ + “2”2 as in Figure 3
1...

Cut is made at position t of an-aA. At this time, since the front gap portion is laser welded, the machining force during cutting will not degrade the gap length accuracy and track matching accuracy. In fact, in this example, the cutting efficiency is high, so it goes without saying that the cutting strength of the laser welded part is sufficient even for cutting with a thin-blade peripheral cutting machine that applies a relatively large processing force. Long accuracy and track matching accuracy did not deteriorate at all.

The front end of the front gap section obtained as described above is laser welded, and the pack gap section is connected to the plurality of magnets bonded with silver solder, as shown in Fig. 6.
At 18.19, it is fixed to the magnetic head base 17 by laser welding.

In this embodiment, stainless steel was used for the magnetic head base 17 in consideration of weldability, but at this time, the thermal expansion coefficient of the magnetic head chip is slightly smaller than that of the magnetic base 17. Laser welding is performed while the RAD chip and magnetic RAD base are heated and maintained at a temperature sufficiently higher than the maximum temperature expected in the actual usage environment. Heating can be easily performed by irradiating focused infrared rays. In this way, since the two are bonded at a temperature higher than the maximum temperature in actual use,
Regardless of any actual fluctuations in ambient temperature, the gap length is extremely stable because thermal stress based on the difference in thermal expansion between the magnetic base and the magnetic tip is generated so as to always press the front gap. In this way, the magnetic head tips are fixed to the magnetic head base by laser welding,
After winding the winding window (not shown), the front part is
-b is polished with a lapping tape to complete the final polishing process of the tape sliding portion of the magnetic herad tip, and the laser welded portion 16 is removed. Even after laser weld removal, the front gap surface has
As described above, the thermal stress in the direction of stabilizing the gap length accuracy is sufficiently applied, and the gap length accuracy and track alignment accuracy do not deteriorate in actual use.

Now, in FIG. 6, the laser welded part 16 of the front gear and the prong part is shown with diagonal lines, but in reality, the part melted by the laser and the base metal cannot be distinguished at all from the appearance.

Therefore, there is no problem if the amount of polishing is set to be large considering the variation in the penetration depth by the laser, but in some cases, as shown in Figure 7, there may be a track on the front gap forming surface. Providing the grooves 20 and 21 facing each other along the width direction also has sufficient merits.

In other words, due to the presence of the grooves 20 and 21, the upper limit of the laser penetration depth is regulated to a constant value by the width V in the figure, and the groove also prevents heat conduction along the front gap surface during welding. Therefore, when the laser welded part is later removed by polishing, by polishing only a certain dimension V, the magnetic head chip 2. is completely free from any thermal influence due to welding. can be obtained.

In the above embodiments, the pack gap surfaces were joined with silver solder, but it is of course possible to join the pack gear knob surfaces with laser welding.

Next, the case of an audio head will be described.

As shown in FIG. 8, Sendust's core block 21.
22 are opposed to each other, a front gap portion is formed by the glass vapor deposited films 14 and 15, and in this down position, laser welding 23 is performed at the front end of the front gap portion. This welding may be done continuously in a seam shape, but
As shown in Fig. 8, at the cutting position where chips of a predetermined thickness are to be cut, the unwelded part 2 is not intentionally welded.
4, it becomes possible to check the gap length accuracy in the unwelded portion, as in the embodiment for the video head described above. The core blocks 21 and 22 joined in this way are cut to a predetermined thickness, and
Obtain a magnetic herad tip.

At this stage, the magnetic circuit for the magnetic head has not yet been formed on this magnetic head chip. To this magnetism, as shown in Fig. 9, laser welding 18.19 is performed on the magnetic and Rad base 17, and other magnetic material 26 shown by the dashed line is joined to complete the magnetic circuit as the magnetic head. , a winding (not shown) is applied, and the laser welded portion at the front gap portion is removed to complete the magnetic head.

It should be noted that when a long gear tooth is brought into bath contact with a magnetic head base as in the case of an audio head, it is not necessarily necessary to adjust the temperature fluctuations in the usage environment and heat both of them.

As described above, according to the present invention, in both video heads and audio heads, when cutting a magnetic head member of a predetermined thickness from a joined core block state, the front gap portion is always cut by the laser beam. Because they are joined by welding, gap length accuracy and precision are ensured even for highly efficient cutting.
Track alignment accuracy is not degraded at all, and a highly accurate magnetic head can be manufactured with good mass productivity.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing one step in the conventional magnetic field manufacturing method, Figure 2 is a side view showing another step in the same manufacturing method, and Figure 3 is a side view showing another step in the same manufacturing method. (Perspective perspective) FIG. 4 is a perspective view showing another step of the same manufacturing method. FIG. 5 is a perspective view of one step in an embodiment of the magnetic head manufacturing method of the present invention, FIG. 6 is a side view of another step of the same manufacturing method, and FIG. 7 is a perspective view of another step of the manufacturing method of the present invention. FIG. 8 is a side view of one step in yet another embodiment of the present invention, and FIG. 9 is a side view of another step in the same embodiment. 6.6...Core block, 13...Silver solder adhesive part, 14.15...Glass thin film, 16, 18゜1
9...Laser welding department, 17...Magnetic base O Name of agent Patent attorney Toshio Nakao and 1 other list
2! l Figure 3 Figure 4 Figure 7 Figure 8 Figure 9 Figure 3

Claims (3)

[Claims] (1) Core plates made of two magnetic materials each having a front gear and a gap surface are pressed into contact with each other through a non-magnetic material of a predetermined thickness between the front gap surfaces, and in the pressed state, the above-mentioned opposing After joining the two core blocks by laser welding the front side ends of both front gap surfaces, the joined core blocks are sequentially cut to a predetermined thickness to form at least the front gear. 1. A method of manufacturing a magnetic head, comprising: forming a plurality of plate-like bodies having grooves, joining and fixing the plate-like bodies to a magnetic head base, and then cutting and removing the laser welded portions. (2) When the coefficient of thermal expansion of the plate-shaped body having a front gap is smaller than the coefficient of thermal expansion of the magnetic base, the use of the plate-shaped magnetic material, the magnetic base, the base, and the actual magnetic head. The temperature is kept at a temperature sufficiently higher than the maximum temperature of the environment so that the two are in contact with the laser beam, and conversely, when the coefficient of thermal expansion of the plate-shaped magnetic material is higher than that of the magnetic helad base, both are actually 2. The method of manufacturing a magnetic head according to claim 1, wherein the laser welding is carried out at a temperature sufficiently lower than the lowest temperature of the environment in which the magnetic head is used. (3) At the front end of the front gap surface,
2. The method of manufacturing a magnetic head according to claim 1, wherein laser welding is performed so as to partially leave a portion not to be welded.