JPS6224845B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic head.
It is particularly effective when applied to a magnetic head with a narrow gap length, such as a recording/reproducing head of a video tape recorder.

A method of manufacturing a narrow gap magnetic head for a videotape recorder by forming a thin glass film on the gap forming surfaces of a pair of magnetic head core blocks made of ferrite or the like by a method such as sputter deposition, and press-bonding the film while heating. However, when sputtering lead glass, the lead content of the formed film varies greatly depending on the sputtering power density, and accidents often occur in which the lead glass peels off from the gap.

When forming a gap in a magnetic head by joining the front gap and rear gap with glass, in order to accurately obtain the effective gap length of the front gap, it is desirable to reduce the lead content of the lead-based glass to reduce the reaction layer as much as possible. On the other hand, for the rear gap, it is preferable to use glass with a high lead content in order to increase the adhesive strength, rather than the presence or absence of a reaction layer.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, and to easily obtain a narrow gap with high precision by controlling a glass film of a desired composition from high lead glass used as a sputtering target within an acceptable range. A method of manufacturing a magnetic head is provided.

In general, SiO ₂ , Al ₂ O ₃ ,
For a single glass composition such as PbO, the sputter rate increases as the sputter power density increases. However, PbO is added to constituent glasses such as SiO ₂ , Al ₂ O ₃ , and ZnO.
We have found that when a glass substrate containing PbO is used as a target, the amount of PbO in the sputtered film changes rapidly depending on the sputtering power density. Although the cause of this is not clear, it is thought to be due to a change in adhesion efficiency due to an increase in the temperature of the substrate or selective sputtering. The lead content in the sputtered film decreases rapidly as the power density increases, and at a power density of 3 W/cm ² it becomes less than 1/10 of the target composition.

For example, in the case of glass containing 70 wt% PbO, if the power is set at 1.2 W/cm ² or more, the lead content in the sputtered film will decrease by 20% or more. If the amount of lead in the lead glass decreases by more than 20%, the adhesive strength of the gap will decrease, resulting in delamination from the gap during magnetic head chip assembly, and a decrease in head yield. This is because the melting point of the glass film itself increases due to the decrease in lead, and in order to eliminate this, the gap formation temperature must be raised, and when the formation temperature is raised, the reaction with ferrite progresses rapidly. However, this causes deterioration of recording and reproducing characteristics.

The gap formation conditions in the present invention are carried out in a nitrogen atmosphere at 700 DEG C. to 800 DEG C. In this case, a suitable rear gap bonding has a lead content of 50 to 70 wt%. At this time, the sputter power density is 0.5~
1.2 W/cm ² is appropriate, and 0.7 W/cm ² to 1.0 W/cm ² is optimal. If it is less than 0.5 W/cm ² , the sputtering speed becomes extremely slow and is not practical.

According to the present invention, a glass thin film is formed by sputter evaporation on the gap forming surfaces of a pair of blocks made of high permeability magnetic materials constituting the magnetic head, and the opposing surfaces of the gaps are abutted against each other under constant pressure. In a method for manufacturing a magnetic head, which includes a step of heating and bonding to form a gap in the magnetic head, using lead-containing glass as a sputter target,
When forming a lead glass thin film on the gap forming surface of a magnetic headblock, the sputtering power density is set to 0.5~
The above object was achieved by using a method of manufacturing a magnetic head characterized by bonding under constant pressure in the range of 1.2 W/cm ² at around the melting temperature of the lead glass to form a gap in the magnetic head. be done.

The present invention will be explained in detail below with reference to Examples.

The lead glass target used in the examples of the present invention had the following composition. PbO70wt%, _SiO2 5wt
%, Al ₂ O ₃ 5wt%, B ₂ O ₃ 12wt%, ZnO 8wt%, and the softening temperature is 435°C.

The device used was an RF sputtering device, and the sputtering target substrate had a diameter of 200 mm. Do this 5x
Sputter deposition was performed in an argon atmosphere of 10 ^-3 Torr, and the sputter power density was 0.5 W/cm ² to 4.8 W/
It was carried out in the cm ² range.

FIG. 1 is a diagram showing sputtering power density and film composition variation, and shows the detected ion intensity of each component element analyzed by an X-ray microanalyzer. As is clear from the figure, the amount of Pb 1 decreases rapidly as the sputtering power density increases. for example,
At 1.7 W/cm ² , the Pb amount 1 decreases to 1/15 or less, and the softening temperature becomes around 700°C. On the other hand, the Si amount 2, the Al amount 3, and the B amount 4 hardly change.
However, since the amount of Zn amount 5 decreases somewhat, it is necessary to increase the amount.

In order to obtain a glass film with a composition comparable to that of the sputter target, it is recommended to conduct the process at 0.5 W/cm ² .

Next, the structure of the sputtered film for specifically forming the gap in the magnetic head will be described.

FIG. 2 shows blocks 6 and 7 of a narrow track magnetic head used in a video tape recorder after narrow track processing, with a coil winding groove 8 formed in one of the blocks. Grooves 9 and 10 are for restricting narrow tracks only at the tip of the magnetic head.
The grooves are finally filled with glass to strengthen them.

Next, the gap is formed on the gap facing surfaces 11 and 12.
A sputter-deposited film is formed by the method of the present invention.

The glass film was formed using the configuration shown in FIG. FIG. 3a shows a sectional view of one of the magnetic headblocks, in which a glass film was formed on the front gap forming surface 13 and the rear gap forming surface 14 by the following method.

In order to prevent reaction with ferrite, a lead-free SiO ₂ film with a thickness of 0.24 μm is formed on the front part 13, and a glass film with a power density of 1 W/cm ² is formed on the rear part 14.
After forming a gap of 0.28 μm, a pair of blocks were placed facing each other, held at 770° C. for 3 minutes under pressure in a nitrogen atmosphere, and joined to form a gap of 0.5 μm.
In this case, the front part does not have sufficient adhesive strength, but at the same time it is sufficiently reinforced by the glass filling the narrow track groove. The reason for increasing the film thickness in the rear part is to take into account the fact that the low melting point glass will be slightly crushed in order to raise the temperature to its melting point.

In other embodiments, as shown in Figure 3b, the first layer of the front and rear parts does not contain lead.
A SiO ₂ film 17 of 0.2 μm is formed, and a 0.05 μm glass film 18 containing 60% lead is formed at 0.70 W/cm ² only on the rear part, and is heated under pressure in a nitrogen atmosphere.
They were held at 780°C for 3 minutes and bonded to form a gap of 0.5 μm.

The magnetic head block thus obtained is cut into magnetic head cores 19 as shown in FIG. The groove portion is filled with reinforcing glass 20.

As described above, according to the present invention, a magnetic head having a gap with high precision and high strength can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram illustrating changes in sputter power density and sputter film composition, Figure 2 is a perspective view of a pair of magnetic head processing blocks, Figure 3 is a configuration diagram of a sputter glass film, and Figure 4 is a diagram of the present invention. FIG. 3 is a diagram showing a magnetic head core obtained by.

Claims (1)

[Claims] 1. A thin glass film is formed by sputter deposition on the gap forming surfaces of a pair of blocks made of high magnetic permeability magnetic materials constituting the magnetic head, and the opposing surfaces of the gaps are butted and heated and bonded under constant pressure.
In a method for manufacturing a magnetic head that includes a step of forming a gap in a magnetic head, a lead-containing glass is used as a sputter target, and a sputter power density is set to 0.5 to 1.2 W when forming a lead glass thin film on the gap forming surface of the magnetic head block. ^2. A method for manufacturing a magnetic head, characterized in that the gap of the magnetic head is formed by bonding under constant pressure near the melting temperature of the lead glass.