JPH02187911A - Magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To enhance the thickness accuracy of an insulating film and to decrease the degree of leak magnetic fluxes by a change in the film thickness of an adhesive agent by laminating thin films in order of the insulating film, conductive film and magneto-resistance effect element film on a substrate. CONSTITUTION:The above head is constituted by providing the insulating film 2 on the substrate 1 consisting of a magnetic material, providing the conductive film 9 and the magneto-resistance effect element film 10 thereon, and further, providing the insulating film 6 on the film 10, then adhering a magnetic cover 7 by the adhesive agent 8. The substrate 1 and the cover 7 can be formed of Ni-Mn ferrite, etc., the film 2 and the film 6 of alumina, etc., the film 9 of a highly conductive material, such as Ti, and the film 10 of a ferromagnetic material, such as Ni-Fe alloy, respectively. The leak magnetic fluxes by the difference in the film thickness of the adhesive agent 8 can be decreased according to this constitution and, therefore, the difference in the reproduced outputs between the heads is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetoresistive head among magnetic heads for reading data from a magnetic recording medium.

BACKGROUND OF THE INVENTION FIGS. 4 and 5 are a perspective view and a sectional side view of a conventional magnetoresistive head. 4 and 5, 1 is a substrate made of a magnetic material such as Ni-Mn ferrite;
Reference numeral 2 denotes an insulating film formed on the substrate 1, and the insulating film 2 is made of a nonmagnetic material such as alumina or silicon dioxide. Further, the insulating film 2 is formed using a thin film forming technique such as a sputtering method. Reference numeral 3 denotes a magnetoresistive element film (hereinafter abbreviated as MR element film) formed on the insulator III 2, and the MR element film 3 is made of a ferromagnetic material such as a Ni--Fe alloy. 4 is a conductive film formed on the MR element film 3, and the conductive film 4 is made of a highly conductive material such as Ti. 5
is a lead formed at the end of the conductive film 4, and the lead 5 is made of a material such as copper or gold. 6 is a conductive film 4
The insulating film 6 is formed on the insulating film 2, and the insulating film 6 is made of a non-magnetic material such as alumina or silicon dioxide, like the insulating film 2. 7 is a magnetic cover material, and the magnetic cover material 7 is bonded onto the insulating film 6 with an adhesive 8. Also, the magnetic cover material 7 is made of Ni like the substrate 1.
-Made of magnetic material such as Mn ferrite. Also, the fifth
In the figure, 61 is the thickness of the conductive film 4, the insulating film 6, and the adhesive 8. G2 indicates the thickness of the insulating film 2. Such a magnetoresistive head generally places emphasis on the smoothness of the MR element film 3, and uses an insulating film with good smoothness! Usually, an MR element film 3 is formed on top of the MR element film 2. Because MR
This is because the smoothness of the element film 3 is considered to affect the magnetic properties.

Regarding the conventional magnetoresistive head configured as described above, the relationship between the thickness G1, reproduction output, and second harmonic distortion will be explained. In this example, G2 is 0.6
It was fixed as μm. FIG. 6 is a graph showing the relationship between the thickness G1, reproduction output, and second harmonic distortion of a conventional magnetoresistive head, where the horizontal axis represents the thickness G1, and the unit is μm.

The left vertical axis is the standardized output. The right vertical axis shows second harmonic distortion, and the unit is dB. Here, standardized output is defined as follows. If the maximum reproduction output is Hl and the reproduction output of each thickness G1 is H, the standardized output P is expressed by the following equation.

P=H/H1 In this case, the playback output is maximum when the thickness G1 is 0.4μm, so when G1 is 0.4μm, the standardized output is 1
becomes. First, the relationship between the standardized output and the thickness G1 will be explained. As shown in Figure 6, the standardized output is 0.4 μm for G1.
It increases as the thickness G1 increases. When the thickness G1 further becomes larger than 0.4 μm, the standardized output decreases (The reason why the thickness G1 has such an extreme value is as follows.The adhesive 8 becomes thicker,
When the thickness G1 increases, the magnetic flux generated in the conductive film 4 tends to escape to the outside through the insulating film 6 and the adhesive 8 (as a result, sufficient magnetic flux does not flow into the MR element film 3, so the reproduction output decreases and the standardized output (.Also, as the adhesive 8 becomes thinner and the thickness G1 decreases below 0.4 μm, the magnetic flux generated in the conductive film 4 becomes difficult to escape to the outside, and the The magnetic flux flows into the MR element film 3, and the M
The R element film 3 becomes magnetically saturated. When the magnetic flux of the MR element film 3 becomes supersaturated, the reproduction output decreases and the standardized output decreases.Next, the relationship between the second harmonic distortion and the thickness G1 will be explained.When the thickness G1 is 0.3 μm, When the thickness G1 is thicker or thinner, the second harmonic distortion is the smallest (the second harmonic distortion becomes larger even if the thickness G1 is thicker or thinner than that).Therefore, both the standardized output and the second harmonic distortion are It varies considerably depending on the film thickness between the magnetic cup 7 on which the film 4 is not provided and the conductive film 3, that is, the thickness Gl.

Problems to be Solved by the Invention When the magnetic cover material 7 is bonded onto the insulating film with the adhesive 8, the thickness of the adhesive 8 varies by about 0.1 μm. For example, to minimize second harmonic distortion, 61 is 0.3 μm.
In this case, due to an error in the film thickness of the adhesive 8, a variation of about 0.25 occurs in the standardized output as shown in FIG. That is, the reproduction output of each magnetoresistive head varies considerably depending on the respective heads. Therefore, with the conventional technology, the finished products had considerable variations in reproduction output, resulting in poor yields.

The present invention solves the above-mentioned conventional problems, and can significantly reduce variations in playback output due to differences in adhesive film thickness than before, and reduce variations in magnetic properties, resulting in a magnetoresistive effect with a high yield. The purpose is to provide mold heads.

Means for Solving the Problems In order to achieve this object, an insulating film is provided on a substrate, and a conductive film and a magnetoresistive element film are sequentially provided thereon.

Function: With this configuration, there is only an insulating film between the substrate and the conductive film, and the thickness of the insulating film can be made with high accuracy, reducing the degree of leakage magnetic flux caused by thicker or thinner adhesive films. Can be done.

Embodiment FIGS. 1 and 2 respectively show a perspective view and a sectional side view of a magnetoresistive head according to an embodiment of the present invention. In FIGS. 1 and 2, 1 is a substrate, 2 is an insulating film, 5 is a lead, 6 is an insulating film, 7 is a magnetic cover material, and 8 is an adhesive, which are the same as the conventional structure. Reference numeral 9 denotes a conductive film formed on the insulating film 2, and the conductive film 9 is made of a highly conductive material such as Ti. Reference numeral 10 denotes an MR element film formed only on the conductive film 9, and is made of a ferromagnetic material such as a Ni-Fe alloy. Further, in FIG. 2, Fl is the thickness of the insulating film 6 and the adhesive 8. F2 indicates the film thickness of the insulating film 2 and the conductive film 9.

Regarding the conventional magnetoresistive head configured as described above, the relationship between the thickness Fl, reproduction output, and second harmonic distortion will be explained. In this example, F2 is 0.4μ
It was fixed as m. FIG. 3 is a graph showing the relationship between the thickness Fl, reproduction output, and second harmonic distortion of a conventional magnetoresistive head, where the horizontal axis represents the thickness Fl, and the unit is μm. The left vertical axis is the standardized output. The right vertical axis represents the second harmonic distortion, and the unit is dB. First, the relationship between the standardized output and the thickness Fl will be explained. As shown in Figure 3, the standardized output is for the thickness Fl up to 0.6 μm.
As it increases, it becomes thicker (becomes).
．． As the thickness increases beyond 6 μm, the standardized output decreases. Next, the relationship between second harmonic distortion and thickness Fl will be explained. 2 when the thickness Fl is 0.65 μm
The second harmonic distortion is small (the thickness Fl is thicker or thinner), but the second harmonic distortion is large. Overall, the change is more gradual than that of the normalized output curve.Thickness F that minimizes second harmonic distortion
Since l is 0.65 μm, the film thickness of the adhesive 8 is adjusted to a target of 0.65 μm. However, as mentioned above, there is an error of about 0.1 μm in the film thickness of the adhesive 8. Therefore, as shown in FIG. 3, when considering the variations, a variation of approximately 0.1 occurs in the standardized output. Conventionally, it was approximately 0.
25 had some variation, so a considerable improvement can be seen. The reason why the variation in the standardized output is smaller than before is that the distance of the conductive film 9 to the substrate 1 on which the MR element film 10 is not provided can be determined with great precision. This is because the distance is determined by the thickness of the insulating film 2, and the insulating film 2 is formed using a thin film forming technique such as sputtering. This is because it is formed with an accuracy of Olum-0,005 μm. This is 10 to 20 times better than the accuracy of the film thickness of the adhesive 8.

As described above, according to this embodiment, since the MR element film 10 is formed on the side of the conductive film 9 on which the adhesive 8 is provided, changes in reproduction output due to changes in the film thickness of the adhesive 8 are made more gradual than in the past. , variations in reproduction output due to film thickness errors of the adhesive 8 can be significantly improved.

Effects of the Invention In the present invention, an insulating film is provided on a substrate, and a conductive film and a magnetoresistive element film are sequentially provided on the insulating film, so that there is only an insulating film between the substrate and the conductive film, and the insulating film is Since the film thickness can be adjusted with high precision and the degree of leakage magnetic flux caused by the thickness of the adhesive film can be reduced, the difference in reproduction output between each head can be made much smaller than before. , the yield of magnetic properties can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a magnetoresistive head according to an embodiment of the present invention, FIG. 2 is a sectional view of the same side, and FIG. 3 is a diagram showing the adhesive film thickness, standardized output, and secondary harmonics of this embodiment. A graph showing the relationship between wave distortion, Figure 4 is a perspective view of a conventional magnetoresistive head, Figure 5 is a sectional view of the same side, and Figure 6 is adhesive film thickness, standardized output, and second harmonics. It is a graph showing the relationship between distortions. 1...Substrate 2...Insulating film 5...Lead 6...Insulating film 7...Magnetic cover material 8...・Adhesive 9... Conductive film 10... Name of MR element film agent Patent attorney Shigetaka Awano 1 idiot 1: Substrate 2: Insulating film 5: Lead 6: Insulating film Figure 7 : Magnetic cover material 8: Adhesive 9: Conductive film 10: MR element film Fl (pm) 1st: Substrate 2: Insulating film 3: Magnetoresistive element film 4: Conductive film 5 Figure 5: Lead 6: Insulating film 7: Magnetic cover 8: Adhesive material Gl (μm)

Claims (1)

[Claims] An insulating film is provided on a magnetic substrate, a conductive film is provided thereon, a magnetoresistive element film is provided on the conductive film, an insulating film is further formed to cover the magnetoresistive element film, and the insulating film A magnetoresistive head characterized by having a magnetic cover glued on top of the head.