JPH04355211A - Magnetic head and production thereof - Google Patents

Abstract

PURPOSE:To prevent the generation of the defect by the trouble of a bias magnetic field by regulating the magnitude of a bias resistance by the post working of a resistance circuit for regulation. CONSTITUTION:A bias wire 2 and an MR element 4 are connected in parallel by an electrode terminal part 7. After bias magnetic field intensity HBias is checked in a stage for inspecting the characteristics of the MR magnetic head, plural resistance wires 8 are cut by a laser beam of a micropost or a prober for cutting. The resistance value of a bias circuit is merely required to be lowered and the bias current to be increased when the bias magnetic field after the characteristic inspection is weak. The bias magnetic field to be impressed to the element 4 can be regulated by cutting the resistance wires even if there are fluctuations in the respective element values of the MR type magnetic head, by which the generation of the defect by the trouble of the bias magnetic field is obviated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive magnetic head (hereinafter referred to as MR head) for reproducing magnetic signals.

0002

2. Description of the Related Art Conventionally, a method of applying a bias magnetic field has been used as one of the methods for adjusting the reproduced output waveform obtained by an MR head to a waveform suitable for a purpose.

[0003] This type of conventional MR head will be explained below with reference to the drawings. FIG. 6 shows the configuration of a general magnetoresistive element. A signal magnetic field HS and a bias magnetic field HB are applied to a magnetoresistive element (hereinafter referred to as an MR element) having an axis of easy magnetization in the length direction of the element in a direction perpendicular to the axis of easy magnetization. Further, FIG. 7 shows an operating state in which when an alternating current signal magnetic field HS is applied to the magnetic head of FIG. 6, the output (resistance change amount ΔR) changes depending on the bias magnetic field HB. In order to obtain a desired output waveform, for example, an output with the least waveform distortion, it is necessary to set the bias magnetic field HB to the state shown in FIG. 7(b).

FIG. 8 shows an example of a conventional MR element. Such a bias magnetic field is used in MR as an example of a method of applying HB.
A Ni--Fe alloy (hereinafter referred to as permalloy) 4 as an element and a Ti thin film as a bias line 11 are laminated in a pattern having the same shape. A constant current I between this terminal 12
By flowing, the current is divided into currents that are inversely proportional to the resistance RMR of the MR element 4 and the resistance RBias of the bias line, and the MR current IMR and bias current IBias flow, respectively. At this time, as shown in FIG.
A magnetic field HBias corresponding to Bias is generated.

[0005] In an MR head with such a structure,
Since the MR element and the bias line are connected to a common terminal and a bias magnetic field is applied, there is no need to separately provide a special electric circuit.

[0006]

However, in such a conventional configuration, the strength of the bias magnetic field HBias is
Resistance RMR and bias line resistance RBias, respectively, the specific resistance of the film and the thickness of the film vary from production lot to production lot due to the manufacturing process, so the bias state is not always ideal and the desired output waveform characteristics cannot be obtained. There was a problem in that some defective elements were generated.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and an object of the present invention is to provide a manufacturing method that can produce an MR magnetic head with a high yield and a constant bias current and a desired output waveform. It is something.

[0008]

[Means for Solving the Problem] In order to solve this problem, the MR type magnetic head of the present invention separates the MR element and the bias resistance wire by an insulating layer, and uses a bias resistance adjustment resistor separate from the bias wire main body. The pattern is provided outside the pattern area of the MR element, each resistance wire is connected in parallel at the terminal part, and after measuring the characteristics of the MR head, the resistance wire for bias resistance adjustment is connected so as to obtain the optimum bias magnetic field strength. Post-processing such as cutting or shaving the pattern width is performed.

[0009]

[Operation] By adjusting the size of the bias resistor RBias by post-processing the bias resistor adjusting resistor circuit, it is possible to form a bias magnetic field so as to provide optimum output characteristics.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a magnetoresistive magnetic head according to an embodiment of the present invention. As shown in the figure, a bias line 2, an insulating layer 3 made of Al2O3, etc., and an M
It is formed by stacking R elements 4, and a bias resistance adjustment pattern 6 is formed outside the region 5 of the MR element in the same layer as the bias line 2 and connected in parallel with the bias line. The bias line 2 and the MR element 4 are connected in parallel by an electrode terminal portion 7. In this MR magnetic head characteristic testing step, after confirming the bias magnetic field strength HBias, the plurality of resistance wires 8 are cut with a laser beam from a micro post or a cutting prober. If the resistance of one resistance line 8 of the bias resistance adjustment pattern is R1, then FIG.
), the total of n resistors is R1/n,
By cutting one of them, the resistance becomes R1/(n-1) as shown in FIG. 2(B), and the resistance increases. Figure 3
As shown in Figure 2, the head is manufactured without deviation from the central standard value, and the resistance of the entire bias line that provides an appropriate bias magnetic field is expressed as (Equation 1). This changes the bias resistance adjustment line to m
This is the resistance corresponding to the case of main cutting.

The current flowing through the MR element and the entire bias layer and the bias current are (Equation 2), (Equation 3), and (Equation 4), respectively.
is given by

[0013]

[Math 1]

[0014]

[Math 2]

[0015]

[Math 3]

[0016]

[Math 4]

If it is determined that the bias magnetic field is weak after the characteristic test, the resistance value of the bias circuit may be lowered and the bias current may be increased. At the time of this characteristic test, the number of bias resistance adjustment wires is set to be at least one more than the number of wires in the normal adjustment range (number of wires cut: m±l wires). Here, l is an integer and indicates the width of the number of cuts. In addition, in many cases, as shown in Figure 4, the final number of lines to be corrected can be easily estimated from experimental data by understanding the state of the output waveform during this test, even without pre-processing the bias adjustment line. It is possible. If set, the number of cuts may be m to lower the resistance value of the bias circuit. Conversely, if the bias magnetic field is estimated to be too strong, the number of cuts may be increased.

It should be noted that the bias adjustment of the present invention is not limited to the above embodiment, and as shown in FIGS. , the resistance value may be changed.

[0019]

As is clear from the above description of the embodiments, the MR type magnetic head of the present invention can control the bias magnetic field applied to the MR element even if there are variations in the values of each element of the MR type magnetic head. Adjustment can be made by cutting the resistance wire, so defects due to bias magnetic field problems do not occur.

The same effect as described above can also be obtained by changing the resistance by removing the width of the resistance pattern for bias adjustment using a laser beam or the like.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an MR magnetic head according to an embodiment of the present invention.

[Figure 2] (A) is the circuit diagram before bias resistance modification (B)
is the circuit diagram after bias resistance correction

[Figure 3] Circuit diagram after bias resistance correction

[Figure 4] Graph showing the relationship between the number of bias resistance adjustment patterns and bias magnetic field strength

FIG. 5(A) is a perspective view of an MR magnetic head according to another embodiment of the present invention; FIG. 5(B) is a plan view of the same bias resistance pattern;

[Figure 6] Configuration diagram of a conventional MR type magnetic head

[Figure 7] Graph showing the relationship between bias magnetic field strength and output

[Figure 8] Perspective view of the MR type head

[Figure 9] A perspective view showing the relationship between the bias current and bias magnetic field.

[Explanation of symbols]

1 Board 2 Bias layer 3 Insulating layer 4 MR element 6, 9 Bias resistance adjustment pattern 7 Terminal 8 Resistance wire

Claims (2)

[Claims] 1. A magnetic head in which a head chip is provided with a magnetoresistive element and a bias current line that are insulated from each other, and a resistance pattern is provided in parallel in the same film and layer as the bias current line. 2. A magnetic head in which a resistor pattern is provided in parallel in the same film and layer as the bias current line on a head chip that includes a magnetoresistive element and a bias current line that are insulated from each other. A method of manufacturing a magnetic head in which bias resistance can be independently varied by post-processing the number of patterns or pattern width.