JPS5864612A - Magnetic head - Google Patents

Abstract

PURPOSE:To increase junction strength and the stability of a gap, by welding two magnetic materials at winding window side end parts of back gap parts. CONSTITUTION:On the front gap surfaces 7 and 8 of core blocks 5 and 6, glass vapor-deposited films 14 and 15 for restricting gap length are formed. On back gap surfaces 9 and 10, glass vapor-deposited films 14a and 15a are formed similarly with the front gap surfaces without masking. Then, the core blocks 5 and 6 are butted to each other and the winding window side end parts of the back gap surfaces 9 and 10 are butt-welded so that the direction from the front gap to the back gap coincides with a welding depth direction. For the welding, an optical fiber is inserted into winding grooves 1 and 2, and a laser beam is guided through the optical fiber. The welded core blocks 5 and 6 are placed at a prescribed position and then cut into plate-like magnetic heads.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head, and particularly to a magnetic head suitable for use in a metal core video head. -' Conventionally, when constructing a video head using a metallic magnetic material such as sendust, a pair of core block materials were joined using silver solder, whereas glass was used in the case of ferrite. The main reason for this is that the thermal expansion coefficients of sendust and glass are apocryphal. A magnetic head made by bonding such sendust with a silver foil 6 is manufactured by the following manufacturing process. First, as shown in Fig. 1, winding grooves (1) and (2) for forming winding windows and notches (3i (4)
) are prepared, and then a suitable mask is applied to the back gap (7) and (8), and then the front YAP surface (9) and the mask are applied. On the back gap surface (7) (8),
A non-magnetic material, such as glass, is provided by vapor deposition to a thickness of around 0.8 gn. After this, back gap surface (7)
(8) Peel off the mask applied to expose the sendust surface, and remove the oxide film layer present on the surface with lapping tape or the like. The reason is that the two core blocks (s) (6) are connected to the back gap surface (7) (8)
This is because, if an oxide film layer exists on the surface when bonding with silver solder, the strength of the bond with silver solder will be significantly reduced.

Also, masking the para-multi-gap surfaces (7) and (8) to prevent the formation of a glass vapor deposited film is because strong bonding strength cannot be obtained between the silver solder and the glass vapor deposited film. Next, as shown in FIG.
) (8) A silver solder @Q foil with a thickness of several μm is sandwiched between them, and they are brought together and held with a jig (not shown) so that they can be pressed together. At this time, the accuracy of matching the track portions 01 (6) of the core blocks (6) (6) must be such that the deviation in the track width direction is 1 μm or less. The core block (5) (@) held in this way is heated to a temperature of several hundred degrees, softening the silver solder (2) and promoting diffusion into the core block (6) (6). Block (S
) Perform the silver soldering in (6). Also, at this time, since the core blocks (5) and (6) are pressurized by the jig so that the back gap surfaces (1 (II)) are pressed together, the core blocks (5) and (6) are Blocks (5) and (6) approach each other, and when the silver soldering of both core blocks is completed, as shown in FIG.
(to) contact each other to form a gap portion equal to the thickness of both deposited films.

In addition, in magnetic heads made of ferrite material, the notch parts (3) and (4) are filled with glass to fix and reinforce the track part (b) ring, but in the case of Sendust, glass with a matching coefficient of thermal expansion is used. Since there is no track portion (in(2)), no particular reinforcement is performed on the track portion (in(2)).

Then, in this way, the back gap surface (7) (8)
Core block (5) (6) silver soldered at
By cutting it at a predetermined position, a magnetic head with a thickness of about 200 μm can be obtained.

The magnetic head manufactured as described above has many problems as described below. First, as mentioned above (unlike ferrite heads, the track part is not fixed with glass, so the front gap part is basically free. Therefore, there is no risk of thermal effects, deformation of the head mounting board, vibration, etc.) Due to the influence, the front gap part fluctuates by 0.02 μm or more in gap length accuracy and track alignment accuracy,
As a result, the stability of the magnetic properties of the magnetic field was significantly impaired. In addition, it is extremely difficult to completely remove the fine powder that adheres to the core block that is generated when removing the surface oxidation layer on the back gap surface with roughing tape, and due to the influence of the fine powder that adheres to the front gap, it is difficult to join the core block with silver solder. The gap length accuracy cannot be stably ensured at this stage.
Yield was extremely poor. In addition, when the silver solder becomes soft during the silver soldering process, the silver solder acts like a lubricant, causing the core blocks (6) and (11) to have a relative slip of several degrees in the track width direction. There were many things that happened. For this reason, the yield rate decreased considerably due to track misalignment.

In addition, an extremely large number of man-hours were required for masking and removal of the back gap surface.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a magnetic head that has high bonding strength, high gap stability, and requires fewer manufacturing steps.

The present invention provides a magnetic head in which two magnetic bodies constituting the core of the magnetic head are joined by welding at least the winding window side end of the back gap portion of the core. This allows the molten part, which has an approximately inverted triangular cross section, to cool and solidify during welding.
Due to the volumetric contraction, the front gap parts strongly press against each other, and the dimensional accuracy of the front gap parts becomes stable.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 6. Components that are substantially the same as those in FIGS. 1 to 3 are designated by the same reference numerals, and description thereof will be omitted. First, to briefly explain the manufacturing process of the magnetic head, a glass vapor deposited film Q4w& is formed on the front gap surface (7) (8) of the core block (6) (6) made of a metal magnetic material to regulate the gap length. . At this time, there is no need to mask the back gap surface (9) (if), and the glass vapor deposited film (14i) (15
a) may be formed. Next, as shown in Figure 4, these core blocks (5) and (6) are brought together and the winding window side ends of the back gap surfaces (9 and 2) are moved from the front gap toward the back gap. Butt weld so that the direction is the weld depth direction. This welding is done in the winding groove (
1) This is possible by inserting an optical fiber into (2) and guiding a laser beam to this optical fiber. In the case of Jin, a glass vapor deposited film (14 m) (15 m) was applied to the back gap.
Even if .

Core flock (5) butt welded in this way (
6) is cut at a predetermined position to form a plate-shaped magnetic hood.

According to the configuration of the magnetic head obtained in this way, at the winding window side end of the back gap portion, the direction from the front gap to the back gap, that is, the direction substantially parallel to the depth direction of the gap, is Since welding is performed in the direction of the weld depth, the cross-sectional shape of the molten part a1) at the time of welding is approximately in the shape of an inverted triangle, as shown in Figure 5, and this part is once molten and then cooled and solidified. Therefore, due to the volumetric contraction at that time, the core blocks (6) (6) face each other as shown by arrow A at the fusion zone boundary and are subjected to stress in an oblique direction toward the front gap side. This stress generates a moment in the direction of pressing the glass deposited film axes (2) in the front gap part together between the core blocks (6) (6).
give to

Since this stress is resistant to thermal strain, it becomes quite strong, and therefore the front gap portions are pressed against each other with a considerably strong force. For this reason, the stability of the dimensional accuracy of the front gap is significantly improved compared to the prior art, even without providing a reinforcing glass in the front gap as in the case of a ferrite head. Furthermore, since silver solder is not used, there is no track misalignment that occurs due to silver solder acting as a lubricant, and there is no need for a process to remove the surface oxidation layer on the back gap surface, which occurs during that process. Gap length defects due to fine powder do not occur. Furthermore, since the two core blocks are joined by welding, workability is greatly improved, and the jig for butting the core blocks does not need to be concerned with high-temperature heat resistance, so the jig is simplified.

According to the magnetic head of the present invention, as is clear from the above description, since the two magnetic bodies are welded and joined at the winding window side end of the back gap portion, the joint strength is high and the gap is stable. It has many advantages, such as high performance and easy manufacturing with fewer manufacturing steps.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 to Fig. 8 show a conventional example, Fig. 1 is a perspective view showing the schematic structure of each core block, and Fig. 2 is a front view showing the state of the core blocks when they are joined. , FIG. 8 is a front view of the joined state, FIG. 4 and FIG. 6 show an embodiment of the present invention, and FIG. 4 is a front view of the state in which the core blocks are butted together.
FIG. 5 is an enlarged front view of the bonded state. (5) (6)... Core flock (tB magnetic material, (
7) (8)...Front gap surface, (9) αΦ...
・Back gap surface, axis (to) peak' glass vapor deposited film, (2
)...End of winding window side of back gap part, 0...
Melting zone agent Yoshihiro Morimoto f Fig. 2 B Fig. 2 7ηl Fig. 3 6 Fig. 4 Fig. 5

Claims (1)

[Scope of Claims] 1. A core made of two magnetic bodies that are aligned with each other, and the two magnetic bodies are arranged so that the back gap portion (both ends on the winding window side are connected to the back gear and the bottom gear → A magnetic head that is welded and coupled to a joint whose welding depth direction is substantially parallel to the depth direction of the weld. 1. Claim 1, wherein the magnetic body is a metal magnetic body.
The magnetic head described in section.