JPS58224430A - Hybrid thin film integrated head - Google Patents

Abstract

PURPOSE:To reduce the induction of external noises, by forming a magneto- resistance (MR) head part on which an MR element and an electrode part are formed by thin film depositing method and a semiconductor integrated circuit chip on which a magnetic signal detecting circuit is formed on the same substrate and connecting both the electrodes by a wire bonding method. CONSTITUTION:The substrate 4 is formed by glass, quartz, alumina, ferrite, or the like, the MR head part 5 obtained by forming the MR element 2 and a conductive part 3 to be used as an electrode on a silicon substrate by a thin film depositing lating method is fixed on the substrate 4 and the magnetic recording medium side of the MR head part 5 is covered and protected with an inuslating substrate 5a formed by glass, quartz, or the like. The semiconductor integrated circuit chip 7 consisting of a magnetic signal detecting circuit and a preamplifier is also fixed on the substrate 4. The pad part 8 of the semiconductor integrated circuit chip 7 is electrically connected with the conductive part 3 of the MR head part 5 through a thin wire 9 by a wire bonding method or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hybrid thin film integrated head, and more specifically, 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 per 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 heads that have 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, which is practically difficult to use 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 (abbreviated as MR heads) are attracting attention.

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

In FIG. 1, the reference numeral 1 indicates a substrate, and an MR element 2 is formed on the side surface of the substrate by a thin film deposition method, facing the magnetic recording medium side, and both ends of the MR element 2 are formed on the substrate by a similar method. It is connected to a conductive part 3 formed above.

When 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 changes, resulting in a change in voltage. The strength of the magnetic field can be extracted. The reproduced output voltage ΔV at this time is expressed as Δ■=ΔRI. ΔR
is the resistance change of the MR element due to the external magnetic field, and I is the value of the 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−ρMRX '−・・・・・・・・・・・・・・・
... (1) Xt (]) In the formula, ρMR is the specific resistance value of the MR element, l is the length of the MR element, W is the width, and t is the thickness. As is clear from equation (1), in order to increase the resistance value of the MR element, it is necessary to increase the length and decrease the width and thickness of the MR element.

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

Furthermore, the length of the MR element corresponds to the track width of the reproducing head, and as the recent high-density magnetic recording and reproducing technology requires multi-channel 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 reproduction output also becomes small.

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 values of the conductive parts and lead wires are ignored (3), resulting in an output with a poor S/N ratio. Furthermore, since the conductive portions and lead wires are long, they are subject to the induction of surrounding noise when actually detecting a reproduced signal.

The present invention has been made to eliminate the above-mentioned conventional drawbacks, and provides a thin film magnetic head using an MR element configured to improve the S/N ratio and reduce the induction of external noise. The purpose is to

In order to achieve the above object, the present invention provides an MR head section in which an MR element and an electrode section are formed by a thin film deposition method and a semiconductor integrated circuit chip in which a magnetic signal detection circuit is formed on the same substrate. A structure was adopted in which the electrodes were connected using a wire bonding method.

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.

(4) The reference numeral 5 is an MR head section in which an MR element 2 and a conductive section 3 serving as an electrode are formed on a silicon substrate by a thin film deposition method, and this silicon substrate is fixed onto a substrate 4.

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

Made of alumina, ferrite, etc.

On the other hand, a semiconductor integrated circuit chip indicated by the reference numeral 7 has circuits such as a magnetic signal detection circuit and a preamplifier formed on a silicon substrate, and is fixed on the substrate 4. Then, a thin wire 9 made of aluminum or gold is used to connect the pad section 8, which serves as a connection terminal electrode of the semiconductor integrated circuit chip 1, and the conductive section 3 of the MR head section 5, and electrically conducts the connection by wire bonding or the like. It is connected.

FIG. 4 shows an equivalent circuit diagram of a preamplifier circuit, which is a part of the preamplifier circuit. In FIG. 4, the portion designated by the reference numeral 10 is the MR element portion, and the portions designated by the symbols A and B at both ends thereof correspond to the pad portion 8 and the conductive portion 3 shown in FIG. 3, respectively.

The voltage change caused by the change in resistance of the MR element section 11 is detected by the transistors T, . . . T2, amplified by the transistors 1-3 to T5, taken out as an output OUT, and sent to an external circuit.

Since the present embodiment is configured as described above, 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 of the reproduced signal can be reduced.
/N ratio can be changed.

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, resulting 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 according to 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 significantly reduced.

On the other hand, the output end of the preamplifier is connected to the input end of the next stage using a lead wire as before, and 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. Therefore, even if the same amount of noise occurs in this part as in the conventional case, the S/N ratio can be improved by the amount that the signal has been amplified in advance.

In addition, the resistance of the conductive part and lead wire that take out the signal from the MR element is a source of noise, but in the conventional structure, this noise was generated at a stage where the signal voltage is small before the preamplifier, so s/N (7 ), leading to a decline in

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, and when connecting the MR element to the preamplifier section with a flexible lead wire, 2n lead wires are required. It is.

In contrast, in the structure of the present invention, the preamplifier circuit has one common drive voltage application terminal, one common ground terminal, and four output terminals.
The total number of terminals is n+2.

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 as described above.
It can also be made smaller.

As is clear from the above description, according to the present invention, an MR head section and a semiconductor integrated circuit section are provided on the same substrate,
By adopting a structure in which both electrodes are connected by wire bonding, it is possible to reduce the induction of noise (8), improve the S/N ratio, and also enable miniaturization and high-density mounting. It can be realized.

[Brief explanation of the drawing]

Figure 1 is a partially enlarged plan view explaining the conventional structure, Figures 2-
FIG. 4 explains one embodiment of the present invention, FIG. 2 is a side view of a thin film magnetic head, FIG. 3 is a partially enlarged plan view of the thin film magnetic head, and FIG. 4 is a 14-curve integrated circuit. FIG. 2... MR element 3. S. Conductive part. 5...MR head part 7...Semiconductor integrated circuit chip 8...Pad part 9.R.Thin line Figure 4 Procedural amendment (voluntary) September 1, 1980 Mr. Commissioner of the Japan Patent Office ■, of the case Display 1982 Patent Application No. 108831 2,
Name of invention Hybrid thin film accumulating head 3, relationship with weight of person making correction Name of patent applicant (100) Gyanon Co., Ltd. 4
, agent telephone 03 (268) 2481
(N6, Contents of the Amendment Contents of the Amendment as shown in the attached sheet 1) Next to "silicon" in the first line of page 6 of the specification, add (insulating properties of glass, alumina, ferrite, etc.). 2) Item 6 of the specification Delete "silicon" in the third line of the page and add "the above insulation". 3) Delete ``formed on the same silicon substrate'' in line 1O from page 7, line 9] and add ``because they are formed extremely close to each other''. 4) Correct "4 output terminals" on the 12th line of page 9 to "n output terminals". 179-

Claims (2)

[Claims] (1) A hybrid thin film integrated head characterized in that a magnetoresistive element is formed on the same substrate by a thin film deposition method, an integrated circuit chip is fixed with a slight separation, and the two are electrically connected. (2) The hybrid thin film integrated head according to claim 1, wherein the electrode portion of the magnetoresistive element and the drive electrode portion of the integrated circuit chip are connected by wire bonding.