JPH0447511A - Magneto-resistance effect type thin film magnetic head - Google Patents

Abstract

PURPOSE:To attain the integration of a magneto-resistance effect element with an amplifier and to reduce the noise generated between the magneto-resistance effect element and the amplifier by providing a transformer which detects current change due to the resistance change of the magneto-resistance effect element. CONSTITUTION:In a head chip 4 on which the number of magneto-resistance effect elements (MR element) in accordance with a prescribed number of tracks are provided, surface packaging is applied to the transformers 2 same as the number of MR elements and an IC 6 for amplification provided as the amplifier. The head chip is adhered on a chip supporting board 5 with a flexible printed circuit board 7, and after they are connected electrically with other, the transformer 2 and the IC 6 for amplification, etc., re molded by using resin 8. In other words, such constitution is employed that the primary side coil of the transformer 2 is connected in series with the MR element 1, and the amplifier 3 is connected to the secondary coil side of the transformer 2. Thereby, it is possible to unify the MR element 1 with the amplifier, and to reduce the noise generated between the MR element 1 and the amplifier 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetoresistive type device that uses a magnetoresistive element to detect a signal magnetic field generated by a magnetic recording medium as a change in electrical resistance. This invention relates to thin film magnetic heads.

[Conventional technology]

Conventionally, in magnetoresistive thin-film magnetic heads, the signal magnetic field generated by the magnetic recording medium is transmitted through a magnetoresistive element (
It is detected as a resistance change of the MR element). As shown in FIG. 4, this resistance change is caused by a constant current (■) from the constant current power supply 12. is supplied to the MR element 11 and detected by converting the resistance change into a voltage change. At this time, since the terminal voltage also includes a DC voltage component that is significantly larger than the signal voltage, the DC component is usually cut by the capacitor 13, and then amplified by the amplifier 14 and output.

Since magnetoresistive thin film magnetic heads are magnetic flux responsive heads, they are considered more advantageous than wire-wound thin film magnetic heads, especially in the low frequency range. Furthermore, since the magnetoresistive thin film magnetic head can have a smaller size per track than the wire-wound thin film magnetic head, it is suitable for multi-track applications.

[Problem to be solved by the invention]

However, when constructing a multi-track magnetoresistive thin film magnetic head, the capacitor 13 for cutting the DC component becomes relatively large because the signal voltage includes a signal voltage in a relatively low frequency range. Moreover, since the number of capacitors 13 is required according to the number of trucks, usually the capacitor 13 and the amplifier 1 are
4 is constructed separately from the chip portion containing the MR element of the magnetic head, and a flexible printed wiring board (FP) is connected between the two.
C) etc. However, in this configuration, a very weak signal voltage is transmitted on the FPC, making it vulnerable to external disturbances, and the influence of incoming noise increases significantly, resulting in a decrease in the S/N ratio. .

[Means to solve the problem]

In order to solve the above problems, a magnetoresistive thin film magnetic head according to the present invention includes a magnetoresistive element that outputs a signal magnetic field generated from a magnetic recording medium as a resistance change, and a magnetoresistive element that outputs a signal magnetic field generated from a magnetic recording medium as a resistance change. The device is characterized in that it includes a transformer that detects a change in current due to a change in resistance.

[For production]

According to the above configuration, the signal magnetic field generated from the magnetic recording medium is output as a resistance change by the magnetoresistive element in the magnetoresistive thin film magnet. Then, this resistance change is converted into a current change by a transformer connected to the magnetoresistive element and detected.

At this time, since the volume of the transformer can be made smaller than that of conventionally used capacitors, especially in the case of multi-track magnetoresistive thin film magnetic heads,
It becomes possible to integrate the magnetoresistive element and the amplifier. Therefore, noise generated between the magnetoresistive element and the amplifier is reduced.

Further, when forming a head chip including a magnetoresistive element, a transformer can be incorporated into the head chip together with the magnetoresistive element. As a result, noise can be further reduced.

[Example 1] An example of the present invention will be described below using FIGS. 1 and 2.

The magnetoresistive thin film magnetic head according to this embodiment has a first
As shown in Figure (a), a magnetoresistive effect element (hereinafter referred to as MR
The primary winding of a transformer 2 is connected in series with an element (referred to as an element) 1, and an amplifier 3 is connected to a secondary winding of the transformer 2.

In the above configuration, when detecting a signal magnetic field from a magnetic recording medium, a constant voltage is applied to both ends of the MR element 1 and the transformer 2 on the primary winding side. When a resistance change occurs in the MR element 1, the current flowing through the primary winding of the transformer 2 changes, and this current change causes a voltage change at the secondary winding terminal. Further, by amplifying this voltage change by the amplifier 3, a signal voltage corresponding to the resistance change of the MR element 1, that is, a signal magnetic field from a magnetic recording medium (not shown) is obtained.

The magnetoresistive thin film magnetic head described above can also be configured as shown in FIG. 1(b) by changing the arrangement of the MR element 1 and the transformer 2.

Here, a method for manufacturing a multi-track magnetoresistive thin film magnetic head will be described below with reference to FIG.

First, a head chip 4 on which a number of MR elements corresponding to a predetermined number of tracks is provided is processed from a wafer (not shown) on which a plurality of MR elements are provided, as shown in FIG. 2(a).

On the other hand, as shown in FIG. 2(b), the same number of transformers 2 as the MR elements and an amplifier 1'C6 are surface-mounted on the chip support 5.

Then, as shown in FIG. 2(C), the head chip 4 and the FPC 7 are bonded to the chip support 5, and each is electrically connected by wire bonding or the like.
As shown in d), the above transformer 2...
- By molding the amplification IC 6 and the like, a magnetoresistive thin film magnetic head is obtained. Furthermore, transformer 2.
Although an example has been shown in which transformers 2 are mounted one by one on a support stand, it is also possible to use a structure in which a number of transformers 2 corresponding to the number of tracks are integrated.

[Embodiment 2] Another embodiment of the present invention will be described below with reference to FIGS. 1 and 3. For ease of explanation, members having the same functions as those shown in the drawings of the above embodiment are denoted by the same reference numerals, and their explanations will be omitted.

The magnetoresistive thin film magnetic head of this embodiment basically has the following features:
The configuration is similar to that of the previous embodiment shown in FIG. A method of manufacturing this magnetic head will be explained below with reference to FIG.

First, from a wafer on which a plurality of MR elements and a number of transformers 2 corresponding to the number of MR elements are integrally formed, a number of transformers corresponding to a predetermined number of tracks as shown in FIG. A head chip 9 provided with an MR element and transformers 2 . . . is processed.

On the other hand, as shown in FIG. 3(b), an amplification IC 6 is surface-mounted on the chip support 10.

Then, as shown in FIG. 3(C), the head chip 9 and the FPC 7 are bonded to the above-mentioned chip support 10, and each is electrically connected by wire bonding or the like. As shown, a magnetoresistive thin film magnetic head is obtained by molding the transformer 2, amplification IC, etc. using resin 8.

In addition, in the above embodiments 1 and 2, the number of secondary windings of the transformer 2 is greater than the number of primary windings (by doing so, it is also possible to provide a voltage amplification function.Furthermore,
Although only up to the amplification IC 6 is mounted on the chip support stands 5 and 10, up to a part of the multiplexer for converting parallel processing to time series processing is mounted on the chip support stands 5 and 1.
It is also possible to implement it on top of 0. In this case, there is an advantage that the number of wires in each of the FPCs 7, 7 connected to the chip support stands 5, 10 can be significantly reduced.

[Effects of the Invention] As described above, the magnetoresistive thin film magnetic head according to the present invention includes a magnetoresistive element that outputs a signal magnetic field generated from a magnetic recording medium as a resistance change, and a magnetoresistive element that outputs a signal magnetic field generated from a magnetic recording medium as a resistance change. This configuration includes a transformer that detects a change in current due to a change in resistance.

At this time, since the volume of the transformer can be made smaller than that of conventionally used capacitors, especially in the case of multi-track magnetoresistive thin film magnetic heads,
It becomes possible to integrate the magnetoresistive element and the amplifier. Therefore, there is an effect that the noise generated between the magnetoresistive element and the amplifier is significantly reduced.

Further, when forming a head chip including a magnetoresistive element, a transformer can be incorporated into the head chip together with the magnetoresistive element. As a result, it is possible to further reduce noise, improve the S/N ratio of the magnetoresistive thin film magnetic head, and obtain a high quality magnetoresistive thin film magnetic head.

[Brief explanation of drawings]

1 and 2 show one embodiment of the present invention. FIGS. 1A and 1B are circuit diagrams showing the structure of a magnetoresistive thin film magnetic head. FIGS. 2(a) to 2(d) are perspective views showing the manufacturing process of a magnetoresistive thin film magnetic head. FIGS. 3(a) to 3(d) show another embodiment of the present invention, and are perspective views showing the manufacturing process of a magnetoresistive thin film magnetic head. FIG. 4 shows a conventional example, and is a circuit diagram showing the structure of a magnetoresistive thin film magnetic head. 1 is a magnetoresistive element, and 2 is a transformer. Patent applicant Sharp Corporation Figure (a) Figure (b) 1st! ! (C) Figure (d) Figure (a) Figure (b) ]○ Part f! ! (C) Figure (d) Figure c

Claims (1)

[Claims] 1. A magnetoresistive thin film magnet that includes a magnetoresistive element that outputs a signal magnetic field generated from a magnetic recording medium as a resistance change, and a transformer that detects a current change accompanying the resistance change output from the magnetoresistive element. head.