JPH0474766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film integration head, and more particularly to a thin film integration head using a magnetoresistive element (hereinafter abbreviated as MR element).

Thin film magnetic heads have been widely adopted to increase recording density and improve frequency characteristics.

For example, this thin-film magnetic head is ideal for magnetic heads that require a large number of head elements and a high degree of integration for each head element in order to meet the demands for multi-channel use, such as in digital audio recorders. It is considered a thing.

However, when looking at playback heads, the playback voltage of the magnetic induction type thin-film magnetic head that has been widely used in the past is proportional to the relative speed between the head and the magnetic recording medium, so at low speeds, the playback output is also low. In order to accommodate this, it is necessary to increase the number of turns of the coil, from several hundreds to thousands of turns, making it practically difficult to use it as a thin film reproducing head.

On the other hand, in order to support such thin-film magnetic heads, thin-film magnetic heads (hereinafter referred to as MR heads) that use magnetic flux-responsive magnetoresistive elements that are unrelated to the relative velocity between the head and the magnetic recording medium are attracting attention. It's been a long time since I've been in the middle of a long time since I've been in the middle of a long time.

An example of such an MR head is shown enlarged in FIG.

In FIG. 1, what is indicated by the reference numeral 1 is a substrate;
On its side, facing the magnetic recording medium side, there is an MR element 2.
is formed by a thin film deposition method or the like, and both ends of the MR element 2 are connected to conductive parts 3 formed on the substrate by a similar method.

If a constant current is supplied to the MR element 2 of the MR head having the above structure through the conductive part 3, when an external magnetic field approaches, the resistance value of the MR element 2 will change, resulting in a change in voltage. The strength of the magnetic field can be extracted. Reproduction output voltage ΔV at this time
is expressed as ΔV=ΔRI. ΔR is due to the external magnetic field
In the resistance change of the MR element, I is the value of a constant current applied to the MR element. The rate of change in resistance of the MR element 2 caused by an external magnetic field is generally
-1 to 3% for MR elements made of Fe, Ni-Co, etc.
It is.

Therefore, in order to obtain a large reproduction output, it is necessary to increase the absolute resistance value of the MR element.
The resistance value R of the MR element is generally expressed by the following equation (1).

R=ρ _MR ×l/w×t...(1) In equation (1), ρ _MR is the specific resistance value of the MR element, l
represents the length of the MR element, w represents the width, and t represents the thickness. No.
As is clear from equation (1), in order to increase the resistance value of the MR element, the length of the MR element must be increased,
It is necessary to reduce the width and thickness.

However, the thickness of the MR element cannot be made very thin because the element is created using thin film technology.
The width of the MR element cannot be made very small due to limitations in photoetching technology.

In addition, the length of the MR element corresponds to the track width of the read head, and as the recent high-density magnetic recording and playback technology requires multichannel and high integration, it is necessary to reduce the track width.
There is a need to reduce the length of elements.
As a result, as is clear from equation (1), there is a drawback that the reproduced output also becomes smaller.

Furthermore, when mounting an MR element, it is necessary to connect the conductive part with a flexible lead wire and connect it to the preamplifier circuit part to obtain a reproduced output signal.

As a result, the resistance value of the conductive portion and the lead wire cannot be ignored, resulting in an output with a poor S/N ratio. Since the conductive parts and lead wires become long, when actually detecting the reproduced signal,
This causes noise to be induced in the surrounding area.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology.
The object of the present invention is to provide a thin film magnetic head using the device.

In order to achieve the above object, according to the present invention,
In a thin film integrated head in which a plurality of head sections formed of magnetoresistive elements, an integrated circuit section including a preamplifier circuit, and a plurality of output side electrode sections are arranged on the same silicon substrate, The silicon substrate is fixed on a first insulating substrate of large dimensions, the head portion on the silicon substrate is connected to the preamplifier circuit of the integrated circuit section, and is covered with a second insulating substrate, and A structure was adopted in which a flexible lead wire was fixed to a portion of the first insulating substrate where the silicon substrate was not present, and the output side electrode portion on the silicon substrate and the flexible lead wire were connected with a wire.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

The reference numeral 4 in FIG. 2 is an insulating substrate made of glass, quartz, alumina, ferrite, or the like.

Reference numeral 5 designates an integrated head section in which an MR element and an integrated circuit section are formed on a silicon substrate.

This integrated head section 5 is fixed on a substrate 4, and its tip end, that is, the magnetic recording medium side, is covered with an insulating substrate 6 for protecting the MR element part. This insulating substrate 6 is also made of glass, quartz, alumina, ferrite, or the like.

On the other hand, what is indicated by the reference numeral 7 is a lead wire for electrically connecting the integrated circuit formed in the integrated head section 5 to an external circuit. The connection is being made.

FIG. 3 shows a partially enlarged view of the collecting head section 5, and the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 3, the reference numeral 9 is an electrode portion, which is a portion that becomes an input terminal. Also code 10
What is shown by is the output side electrode part of the integrated circuit.

In FIG. 3, the part between the lines X-X and Y-Y is the integrated circuit part, and FIG. 4 shows an equivalent circuit diagram of the preamplifier circuit that is part of the integrated circuit part. In FIG. 4, the portion designated by reference numeral 11 is the MR element portion, and the portions designated by symbols A and B at both ends thereof correspond to the electrode portion 9 and the conductive portion 3 shown in FIG. 3, respectively.

The voltage change caused by the resistance change of the MR element section 11 is detected by the transistors T ₁ and T ₂ and amplified by the transistors T ₃ to _{T 5} .
It is taken out as the output OUT and sent to the external circuit.

Next, the integration head section 5 having such a structure will be described.
An outline of the manufacturing method is described below.

The preamplifier of the integrated head section 5 is the same as the general IC manufacturing process, except for the electrode sections 9 and 10, which are electrically protected by an insulating layer such as phosphate glass.

Next, an MR element part made of permalloy, Ni/Co alloy, etc. and a conductive part made of aluminum, copper, gold, etc. are formed thereon by a sputtering method, vapor deposition method, plating method, etc., and the conductive part 3 is formed by a photoetching method. , the electrode portion 9, and the MR element 2 may be formed by selective etching.

Since this embodiment is configured as described above,
Since the MR element and the preamplifier integrated circuit section are formed on the same silicon substrate, the distance between them can be shortened, and the S/N ratio of the reproduced signal can be improved.

When using an MR head, noise generated by the induced magnetic field crossing the signal line connecting the MR element and preamplifier becomes a problem, but the magnitude of this noise is proportional to the cross-sectional area of the closed loop formed by the signal line. do.

For this reason, in the conventional example, the MR element and the preamplifier located at a remote location were connected by a lead wire such as a flexible lead wire, which resulted in a large cross-sectional area of the aforementioned closed loop and a large amount of noise.

On the other hand, in the thin-film magnetic head of the present invention, the MR element and preamplifier are arranged extremely close to each other, so the cross-sectional area of the closed loop formed by the signal line connecting them can be almost ignored, and the amount of noise can also be reduced. can be significantly reduced.

On the other hand, the connection from the output end of the preamplifier to the input end of the next stage will be connected with a lead wire as before.
Noise is generated in this part due to the induced magnetic field, but in the structure of the present invention, the signal component is amplified by the preamplifier, so even if the same amount of noise is generated in this part as in the conventional case, the signal is amplified in advance. The S/N ratio can be improved by that amount.

Furthermore, the resistance of the conductive parts and lead wires that take out signals from the MR element is a source of noise, but in the conventional structure, this noise also occurred at a stage where the signal voltage was small before the preamplifier.
This caused a decrease in the S/N ratio.

However, in the structure of the present invention, since the resistor of the lead wire portion is located at the subsequent stage of the preamplifier, the noise caused by this can be ignored.

Furthermore, in the conventional structure, when using n MR elements, the number of connection terminals is 2n,
2n lead wires are also required when connecting the MR element to the preamplifier section using flexible lead wires.

In contrast, in the structure of the present invention, the preamplifier circuit has one common drive voltage application terminal and one common ground terminal.
A total of n + 2 terminals (n output terminals) is sufficient. As a result, as the number of MR elements mounted increases to two or more, the number of terminals is reduced, so the structure of the present invention becomes more advantageous, and not only improves the S/N ratio mentioned above, but also reduces the size. It is measured.

As is clear from the above description, according to the present invention, a plurality of head parts formed of magnetoresistive elements, an integrated circuit part including a preamplifier circuit, and a plurality of output side electrode parts are formed on the same silicon substrate. and a thin film integration head in which the silicon substrate is fixed on a first insulating substrate larger in size than the silicon substrate, and the head portion on the silicon substrate is connected to the preamplifier circuit of the integrated circuit portion. and covered with a second insulating substrate, and fixing a flexible lead wire to a portion of the first insulating substrate where the silicon substrate is not present;
By adopting a structure in which the output side electrode part on the silicon substrate and the flexible lead wire are connected with a wire, noise induction can be reduced, the S/N ratio can be improved, and miniaturization is possible. High-density packaging of multiple channels can be achieved. Additionally, flexible lead wires can be connected reliably.

[Brief explanation of the drawing]

Figure 1 is a partially enlarged plan view illustrating the conventional structure;
2 to 4 illustrate one embodiment of the present invention, in which FIG. 2 is a side view of a thin film magnetic head, FIG. 3 is a partially enlarged plan view of an integrated head section, and FIG. 4 is an integrated FIG. 3 is an equivalent circuit diagram of a preamplifier portion of the circuit. 2...MR element, 3...Conductive part, 5...Integration head part, 7...Flexible lead wire, 9, 10
……electrode.

Claims (1)

[Scope of Claims] 1. A thin film integrated head in which a plurality of head sections formed of magnetoresistive elements, an integrated circuit section including a preamplifier circuit, and a plurality of output side electrode sections are arranged on the same silicon substrate. In this step, the silicon substrate is fixed on a first insulating substrate having a larger size than the silicon substrate, a head portion on the silicon substrate is connected to a preamplifier circuit of the integrated circuit portion, and a second insulating substrate is connected to the preamplifier circuit of the integrated circuit portion. a flexible lead wire is fixed to a portion of the first insulating substrate that is covered with a substrate and where no silicon substrate is present, and the output side electrode portion on the silicon substrate and the flexible lead wire are connected with a wire; A thin film integrated head featuring: