JPH0447510A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To attain miniaturization by providing a magneto-resistance effect element (MR element) and a transformer for signal detection which converts a current change due to the change of electrical resistance of the MR element to a voltage change integrally on a substrate. CONSTITUTION:The transformer 13 for signal detection is comprised of lead wires 4a, 4b drawn out from both terminals of the MR element 3 and formed spirally on a first insulating layer 2, a magnetic substrate 1, and a magnetic layer 6. When the electrical resistance in the MR element 3 is changed corresponding to a magnetic field from the outside, the current on the lead wire 4a as the primary coil of the transformer 13 for signal detection is changed, and the voltage is induced on the lead wire 4b as a secondary coil, and the voltage changing corresponding to the magnetic field generated between a draw-out wire 9b and the lead wire 4b is outputted. Thereby, it is not required to use a capacitor for coupling with large volume, and the unification of the magneto-resistance effect element 3, the transformer 13 for signal detection, and an IC 14 for amplification can be realized, which attains the miniaturization.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetoresistive element (hereinafter abbreviated as MR element).
The present invention relates to a thin film magnetic head equipped with a thin film magnetic head.

[Conventional technology]

FIG. 8 shows a circuit configuration when recording information on a magnetic recording medium is detected by a thin film magnetic head equipped with an MR element.

A constant current 1c is supplied to the MR element 3 from a constant current source 19, and when a magnetic field that changes according to the recorded information is applied to the MR element 3 from the magnetic recording medium in this state, the electricity of the MR element 3 changes. The resistance changes according to the magnetic field, and the voltage across the MR element 3 changes accordingly, so that changes in the magnetic field depending on recorded information are detected as changes in voltage. Then, the DC component is removed by a coupling capacitor 20, and the AC component is transferred to an amplifying IC (integrated circuit).
14 and is amplified, and the information is reproduced from the output signal.

[Problem to be solved by the invention]

However, in the above conventional configuration, the SN ratio (signal to noise ratio)
When trying to manufacture a thin film magnetic head that integrates the MR element 3, condenser 20, and amplification IC 14 in order to improve have.

In particular, in the case of a multi-track type thin film magnetic head, it is necessary to provide the same number of capacitors 20 as the number of 3 MR elements.
This leads to an increase in the size of the thin film magnetic head, making it difficult to integrate it.

[Means to solve the problem]

In order to solve the above problems, the thin film magnetic head of the present invention includes a magnetoresistive element whose electrical resistance changes depending on a magnetic field, and a signal that converts a current change accompanying the electrical resistance change of the magnetoresistive element into a voltage change. A detection transformer is integrally provided on the substrate, and a primary winding and a secondary winding of the signal detection transformer are formed by lead wires taken out from the magnetoresistive element. It is said that

[For production]

According to the above configuration, the magnetoresistive element whose electrical resistance changes depending on the magnetic field and the signal detection transformer which converts the current change accompanying the electrical resistance change of the magnetoresistive element into a voltage change are integrally mounted on the substrate. In addition, since the primary and secondary windings of the signal detection transformer are formed from lead wires taken out from the magnetoresistive element, small-sized signals can be generated without using a large-capacity coupling capacitor. A detection transformer can be used to extract voltage changes in response to changes in the magnetic field. As a result, the magnetoresistive element,
It becomes possible to construct a compact thin-film magnetic head that integrates a signal detection transformer and an amplification IC.

[Embodiment 1] An embodiment of the present invention will be described below based on FIGS. 1 to 4. Note that members having the same functions as those shown in the drawings of the conventional example are given the same reference numerals.

As shown in FIG. 4, the circuit configuration of the thin film magnetic head used in this embodiment basically consists of an MR element 3 and a signal detection transformer 13. is connected in series with the primary winding of. On the other hand, the secondary winding of the signal detection transformer 13 is connected to an externally provided amplification IC 14.

In the above configuration, a constant voltage Vc is applied to the MR element 3 via the primary winding of the signal detection transformer 13. In this state, when a magnetic field that changes according to recorded information is applied to the MR element 3 from a magnetic recording medium (not shown), the M
The electrical resistance of the R element 3 changes according to the magnetic field, and the current flowing through the primary winding of the signal detection transformer 13 changes accordingly. Then, a voltage is induced across the secondary winding due to mutual induction, which is input to the amplification IC 14 and amplified, and information is reproduced from the output signal.

The thin film magnetic head of this example is shown in FIGS. 1(a) and (b).
As shown in FIG.
An MR element 3 made of a magnetic thin film having axial magnetic anisotropy, lead wires 4a and 4b taken out from both ends of the MR element 3 and formed in a spiral shape on the first insulating layer 2, and also a first insulating layer 2. Leading lines 9a and 9b formed on layer 2 and MR
A second insulating layer 5 formed to cover the element 3, lead wires 4a and 4b, and lead wires 9a and 9b, and a magnetic layer 8 formed on the second insulating layer 5 to cover the MR element 3. , a conductor 7a that electrically connects the end of the lead wire 4a and the end of the lead wire 9a, and the end of the lead wire 4b and the lead wire 9.
The conductor 7b electrically connects the end of the lead wire 4b from the magnetic substrate 1 through the center of the spiral of the lead wire 4a and returns to the magnetic substrate 1 through the center of the spiral of the lead wire 4b. A magnetic layer 6 is provided.

Here, the magnetic substrate 1 and the magnetic layer 8, which are provided to sandwich the upper and lower surfaces of the MR element 3, constitute a magnetic shield for the MR element 3, and unnecessary magnetic fields from the outside are transmitted to the MR element 3.
I try not to have any negative impact on the. Further, the magnetic substrate 1 and the magnetic layer 6 constitute a magnetic circuit, and the spirals of the lead wires 4a and 4b correspond to the primary winding and secondary winding wound around this magnetic circuit, respectively. are doing. In other words,
The magnetic substrate 1, the magnetic layer 6, and the lead wires 4a and 4b constitute a signal detection transformer 13.

In the above configuration, a constant voltage Vc is applied between the lead wire 9a and the lead wire 4b. When the electrical resistance of the MR element 3 changes in accordance with the external magnetic field, the lead wire 4 as the primary winding of the signal detection transformer 13 changes accordingly.
As the current flowing through a changes, a voltage is induced in the lead wire 4b as a secondary winding due to mutual induction, and a voltage that changes depending on the magnetic field is output between the lead wire 9b and the lead wire 4b.

In order to manufacture the above-mentioned thin film magnetic head, as shown in FIG. The MR element 30 of the 0th order forms the MR element 3
At the same time, lead wires 4a and 4b made of, for example, Affi are formed in a spiral shape so as to be electrically connected to both ends.
Lead lines 9a and 9b are also formed.

After that, as shown in FIG.
A second insulating layer 5 made of, for example, Sin is formed on the entire surface so as to cover the i4a and 4b and the lead wires 9a and 9b.
Next, in order to electrically connect the lead wire 4a and the lead wire 9a, the second insulating layer 5 on the end of the lead wire 4a and the second insulating layer 5 on the end of the lead wire 9a are subjected to RIE ( The contact holes 10a and 10a are formed by removing the contact holes 10a and 10a by a reactive ion etching method or the like. Similarly, in order to electrically connect the lead wire 4b and the extraction wire 9b,
Contact holes 10b/llb are formed. At the same time, the signal detection transformer 13 (FIG. 1(b)
), the first insulating layer 2 and the second insulating layer 5 on the center portions of the spirals of the lead wires 4a, 4b are removed to form contact holes 12, 12.

Next, a magnetic layer 8 (first
Figures (a) and (b)), the end of the lead wire 4a and the lead wire 9
A conductor 7a that electrically connects the end of the lead wire 4b and the end of the lead wire 9b, and a magnetic circuit of the signal detection transformer 13. A magnetic material Ji6 for closing is simultaneously formed using a metal soft magnetic material film such as a Ni--Fe alloy thin film.

[Embodiment 2] Another embodiment of the present invention will be described below based on FIGS. 5 to 7. For convenience of explanation, members having the same functions as those shown in the drawings of the above-mentioned embodiments are denoted by the same reference numerals, and their explanations will be omitted.

The circuit configuration of the thin film magnetic head used in this embodiment is the same as that of the previous embodiment (FIG. 4).

The thin film magnetic head of this example is shown in FIGS. 5(a) and (b).
As shown in FIG. layer 2, an MR element 3 made of a magnetic thin film having uniaxial magnetic anisotropy formed on the first insulating layer 2; The lead wires 4a and 4b formed on the first insulating layer 2, the lead wires 9a and 9b formed on the first insulating layer 2, and the MR element 3 and the lead wires 4a and 4.
b and the second line formed to cover the lead lines 9a and 9b.
An insulating layer 5, magnetic layers 16 formed on the second insulating layer 5 so as to surround the MR element j from left and right, and lead wires 4.
A conductor 7a that electrically connects the end of lead wire 9a and the end of lead wire 9a, a conductor 7b that electrically connects the end of lead wire 4b and the end of lead wire 9b, and a magnetic material. Read from board 1! 4a, and a magnetic layer 6 provided so as to return to the magnetic substrate 1 via the center portion of the lead wire 4b.

Here, the magnetic substrate 1 and the magnetic layers 16, 16, which are provided so as to sandwich the upper and lower surfaces of the MR element 3, each have an MR element.
The third insulating layer 15, which constitutes the lower yoke and the upper yoke of the element 3, and which is provided between the magnetic substrate 1 and the magnetic layer 16, constitutes a gap layer. That is, the magnetic field corresponding to the recorded information is guided by the upper and lower yokes made up of the magnetic substrate 1 and the magnetic layers 16 and 16, and reaches the MR element 3. Further, the magnetic substrate 1 and the magnetic layer 6 constitute a magnetic circuit, and the spirals of the lead wires 4a and 4b are the primary winding and the secondary winding wound around this magnetic circuit, respectively.
Compatible with the next winding. That is, the magnetic substrate 1, the magnetic layer 6, and the lead wires 4a and 4b are connected to the signal detection transformer 13.
It consists of

In the above configuration, a constant voltage Vc is applied between the lead wire 9a and the lead wire 4b. When the electrical resistance of the MR element 3 changes in accordance with the external magnetic field, the lead wire 4 as the primary winding of the signal detection transformer 13 changes accordingly.
As the current flowing through a changes, a voltage is induced in the lead wire 4b as a secondary winding due to mutual induction, and a voltage that changes depending on the magnetic field is output between the lead wire 9b and the lead wire 4b.

In order to manufacture the above-mentioned thin film magnetic head, as shown in FIG. After forming the first insulating layer 2 made of, for example, Stow so as to cover the insulating layer 15, an MR element 3 made of a magnetic thin film such as a Ni-Fe alloy thin film is formed. For example, A! While forming the lead wires 4a and 4b in a spiral shape,
Lead lines 9a and 9b are also formed.

After that, as shown in FIG. 7, the MR element 3 and the lead wire 4 are
A second insulation 1ii5 made of, for example, 5iCh is formed on the entire surface so as to cover the lead wires 9a and 9b and the lead wires 9a and 9b.
Next, in order to electrically connect the lead wire 4a and the lead wire 9a, the second insulating layer 5 on the end of the lead wire 4a and the second insulating layer 5 on the end of the lead wire 9a are subjected to RIE ( The contact holes 10a and 10a are formed by removing the contact holes 10a and 10a by using a reactive ion etching method or the like. Similarly,
Contact holes 10b and llb are formed to electrically connect the lead wire 4b and the extraction wire 9b. At the same time, the signal detection transformer 13 (Fig. 1 (
In order to provide the magnetic circuit of b)), lead wires 4a and 4b are
The first insulating layer 2 and the second insulating layer 5 on the central part of the spiral are removed to form contact holes 12, 12, and to provide magnetic layers 16, 16 as an upper yoke of the MR element. The first insulating layer 2 and the second insulating layer 5 on both the left and right sides of 3 are removed to form contact holes I7 and 18.

Next, the magnetic layer 16- as the upper yoke of the MR element 3
16 (FIGS. 5(a) and 5(b)), a conductor 7a that electrically connects the end of the lead wire 4a and the end of the lead wire 9a, and a conductor 7a that electrically connects the end of the lead wire 4b and the end of the lead wire 9b. A conductor 7b for electrically connecting the end portions and a magnetic layer 6 for closing the magnetic circuit of the signal detection transformer 13 are simultaneously formed using a metal soft magnetic film such as a Ni-Fe alloy thin film.

In the above embodiments, in order to improve production efficiency, the magnetic layers 6 and 8 (Fig. 1) or the magnetic layers 8 and 16 and the conductors 7a and 7b were simultaneously formed using the same metal soft magnetic film. However, it may be formed of a different material. By doing so, the magnetic layers 6, 8, and 16 do not necessarily need to be made of metal, and the conductors 7a and 7b also do not need to be soft magnetic materials, so that optimal materials can be selected for each. Moreover, instead of the magnetic substrate 1, a Sin.

A substrate in which a magnetic layer is formed on a non-magnetic substrate such as a substrate may also be used. By doing so, the selection range of substrates is expanded. Moreover, in the signal detection transformer 13,
The number of turns of the primary winding and the secondary winding consisting of the leads IA4a and IA4b is one, but by making more turns, the mutual induction becomes stronger and the induction loss becomes smaller. Furthermore, by increasing the number of turns of the secondary winding relative to the number of turns of the primary winding, voltage amplification can also be achieved.

〔Effect of the invention〕

As described above, the thin film magnetic head of the present invention includes a magnetoresistive element whose electrical resistance changes depending on a magnetic field, and a signal detection transformer which converts a current change caused by the change in electrical resistance of the magnetoresistive element into a voltage change. are integrally provided on the substrate, and the primary and secondary windings of the signal detection transformer are formed from lead wires taken out from the magnetoresistive element, so a large-capacity coupling capacitor can be used. At least, it is possible to extract voltage changes according to magnetic field changes from a small signal detection transformer. As a result, a small and thin Wi! It is now possible to configure a magnetic head, and the wiring from the magnetoresistive element to the amplification IC is short, making it difficult to pick up noise and significantly improving the S/N ratio.

It has the effect of In addition, when applied to a multi-trunk type spring-film magnetic head, by integrating part of the multiplexer for converting parallel processing into time-based processing, C output from multiple thin-film magnetic heads can be reduced to a small number of outputs. Since it can be pulled out with a wire, there are fewer electrical connection points between the pull-out FPC (flexible printed circuit board) and the thin film magnetic head, which simplifies the connection work and reduces the possibility of contact failure. play.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention. FIG. 1(a) is a plan view of the thin film magnetic head. FIG. 1(b) is a sectional view taken along the line AA in FIG. 1(a). FIG. 2 is a plan view showing a stage in which a magnetoresistive element and lead wires are formed. FIG. 3 is a plan view showing a stage in which contact holes are formed. FIG. 4 is a circuit diagram of the thin film magnetic head. 5 to 7 show other embodiments of the present invention. FIG. 5(a) is a plan view of the thin film magnetic head. FIG. 5(b) is a sectional view taken along the line BB in FIG. 5(a). FIG. 6 is a plan view showing a stage in which the magnetoresistive element and lead 1JIA are formed. FIG. 7 is a plan view showing a stage in which contact holes are formed. FIG. 8 shows a conventional example, and is a circuit diagram of a thin film magnetic head. 1 is a magnetic substrate, 3 is an MR element, 4a and 4b are lead wires, 6, 8, and 16 are magnetic layers, 13 is a signal detection transformer, and 15 is a third insulating layer.

Claims (1)

[Claims] 1. A magnetoresistive element whose electrical resistance changes depending on a magnetic field and a signal detection transformer which converts a current change caused by the change in electrical resistance of the magnetoresistive element into a voltage change are provided on the same substrate, and the signal detection transformer is provided on the same substrate. A thin film magnetic head, wherein the primary winding and the secondary winding of the detection transformer are formed by lead wires taken out from the magnetoresistive element.