JPH0243248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wiring device for a multi-channel thin film magnetic head that is compatible with the increasing density of magnetic recording and reproducing devices, and in particular to a wiring device characterized by the structure of the lead line.

2. Description of the Related Art Recently, in magnetic recording and reproducing apparatuses, thin film heads have been widely used as recording and reproducing heads due to remarkable improvements in recording linear density and track density. Multichannel digital recording is rapidly progressing in magnetic tape devices for computers and compact cassette tape recorders for the purpose of increasing density and quality. Therefore, the recording density on magnetic tapes has increased significantly, and magnetic heads are strongly required to have narrower tracks and have multiple channels. The thin film magnetic head technology that makes this possible has improved significantly in recent years.

As recording heads and reproducing heads become multichannel, the wiring on the head chip, especially the structure of the lead lines, becomes important. In the conventional wiring pattern on a head chip, a large deviation occurs in the electrical resistance value between channels, which requires correction by an external circuit. To date, there has been no example of a thin film magnetic head that has been optimally designed for wiring.

Hereinafter, a conventional multi-channel thin film magnetic head wiring device will be explained with reference to the drawings. FIG. 5 shows an example of a conventional multi-channel thin film magnetic head wiring device. In FIG. 5, a magnetoresistive magnetic head (hereinafter referred to as an MR head) for the purpose of reproduction will be explained. In FIG. 5, reference numeral 1 denotes a substrate, which is made of a ferromagnetic material such as Mn--Zn single crystal ferrite. A non-magnetic insulator such as SiO ₂ is deposited on the substrate 1, and a magnetoresistive element (hereinafter referred to as
(referred to as MRE) 2 are arranged in channels 2 ₁ , . . . , 2 _o-1 , 2 _o , . . . 2 _l for l channels.
MRE2 consists of a ferromagnetic thin film such as a Ni-Fe film that has uniaxial magnetic anisotropy. The total track width W is equal to one channel. Each MRE in each channel of MRE2 has electrode terminals 3 (3 ₁ ,
…, 3 _o-1 , 3 _o , …, 3 _l ) and 4 (4 ₁ , …, 4 _o-1 ,
4 _o ,..., 4 _l ) are formed. dashed line 10
The area surrounded by is the magnetic flux sensor section of the reproducing head, which is composed of the MRE 2 and electrode terminals 3 and 4.
Each terminal 3 _{1 ,} . The area surrounded by the two-dot chain line 11 is a pad area for wire bonding, and each pad 7 is formed as a pair with each of the electrode terminals 4, such as pads 7 ₁ , 7 _o-1 , 7 _o , . . . 7 _l . Ru. The pads 7 are arranged at a constant pitch over almost the entire width of the track in the track width direction on the substrate 1. 8 is a group of lead wirings 8 ₁ , . . . , 8 _o-1 , _{8 o ,} .
The electrode terminal 4 ₁ and the pad 7 ₁ are connected by a lead wire 8 ₁ . The same applies to other channels. Both terminals 6 ₁ and 6 ₂ of the common ground line 6 are configured at both ends within the pad area 11 .

The operation of the multichannel MR head configured as described above will be explained. The lead wiring 8 of each channel has a straight line extending perpendicularly to the MRE 2 between the electrode terminal 4 and the pad 7, as shown in FIG.
It is composed of a diagonal line having an angle θ=45 degrees or 135 degrees with this straight line. Assuming that the line width of the electrode terminal 4 of each channel is d and the line width of the pad is constant D, the line widths of the straight portion and the diagonal line portion of the lead wire 8 are d and D/√2, respectively. The point of inflection between the straight line part and the diagonal line part of the lead wiring 8 changes in each channel;
In particular, _8l has no straight line, and only a 45 degree diagonal line extends to pad _8l .

Problems to be Solved by the Invention However, as high-density recording/reproduction progresses rapidly, high-density channel thin-film magnetic heads are required to simplify the head drive circuit, make the entire channel resistance uniform on the head chip, and lower the voltage. Drive is required. At the same time, low resistance is also required for the purpose of reducing heat generation and reproduction noise caused by the resistance value. In the conventional wiring device shown in FIG. 5, the deviation of the resistance values of each channel is large. This amount of deviation is due to resistance value deviation caused by the wiring pattern shape in each channel of the lead wiring 8. In particular, the longer the straight line area of the lead wiring 8, the greater the channel resistance.
The deviation from the channel resistance only in the shaded area becomes large.

As an example, track pitch is 80μm, electrode terminal
d8μm, pad 8 line width D100μm, line spacing 20μm,
Assuming that the number of channels is 20 and the distance between the magnetic flux sensor section 10 and the pad area 11 is approximately 2.7 mm, the lead wiring 8
The maximum to minimum resistance value ratio of (8 ₁ to 8 ₂₀ ) is about twice. In the case of MR heads, uneven channel resistances require channel correction to be made uniform on the external drive circuit side of the MRE2.The greater the number of channels, the more complex equalization becomes, and this becomes a factor in fluctuations in playback output. . In particular, in a recording head, the lower the voltage for thin film coil supply current is driven, the greater the influence of the channel resistance deviation value becomes, and the recording current deviation increases by the deviation value. On the other hand, in the MR playback head, MRE
A constant current sense current is passed through the channel, but in the past, it was necessary to insert a constant current resistance element with an extremely large value in order to absorb the channel resistance deviation, and fine adjustment between channels was required.

In view of the above-mentioned problems, the present invention provides a wiring structure for a multi-channel thin film magnetic head that can make the channel resistance of all channels uniform and reduce the resistance.

Means for Solving the Problems In order to solve the above problems, the wiring device of the present invention has a lead wiring pattern connecting the MR sensor part in the reproducing head or the thin film coil part in the recording head and the pad area for wire bonding. The structure is based on a combination of a straight line part of the lead wiring and a perspective part having a constant inclination angle with respect to the straight line part, and a rule is provided between the line width of the straight line part and the line width of the diagonal line part. That is, the line width of the diagonal line portion having a constant inclination angle is determined so that each resistance value of the channel becomes the same according to the inclination angle. Wiring adjustment for all channels is performed by controlling the lengths of straight lines and diagonal lines in accordance with the above rules. In addition, lower resistance can be achieved by making the straight line width as wide as possible in the above configuration.

Effects With the above-described configuration, the present invention can make the channel resistance values of multiple channels almost uniform and reduce the resistance using only the wiring pattern shape, simplifying the external drive circuit, lowering the voltage drive, and realizing the low resistance between the channels. In addition to suppressing variations in recording and playback sensitivity,
MR heads can suppress thermal noise due to lower resistance. Furthermore, since the wiring pattern can be composed of only a straight line part and a diagonal line part having a certain angle of inclination to the straight line part, for example, 45 degrees or 135 degrees, it is extremely easy to create a photomask.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a schematic plan view of a wiring device for a multi-channel thin film magnetic head according to an embodiment of the present invention.
The relative relationship between the wiring on the recording head or reproducing head chip and the flexible wire 60 in single-sided recording/reproducing with the total track width W is shown. In FIG. 4, 20 is a substrate, 30 is a thin film coil portion in the recording head, the tip of the head is a magnetic flux sensor portion in the MR reproducing head, 40 is a pad area for wire bonding, and 50 is a thin film which is the main part of the present invention. This is a group of lead wires that connect the coil section or magnetic flux sensor section 30 and the pad area 40. The pad area 40 extends over substantially the entire width of the substrate 20, and the pads of each channel are bonded to the conductors 80 of the flexible wire 60 by wires 70 for each channel.

FIG. 1 shows a plan view of a wiring device for a multi-channel thin film magnetic head for reproduction in one embodiment of the present invention. 20 is a highly permeable substrate made of Mn--Zn single crystal ferrite, Ni--Zn ferrite, etc., and a first insulating film (not shown) made of SiO ₂ or the like is attached to this substrate 20. A common ground line 25 is formed on the first insulating film. After forming the common ground line 25, a second insulating layer (not shown) such as SiO ₂ is deposited to form the through hole 24. On the second insulating layer, l MREs 21 (21 ₁ , ..., 21 _o-1 , 21 _o , ...,
21 _l ) is patterned with the required shape and pitch. 22 is an electrode terminal for common grounding of MRE21, respectively MRE21 ₁ ,..., 21 _o-1 , 2
1 _o , ..., 21 _l corresponding to each terminal 22 ₁ , ..., 22
_o-1 , 22 _o , . . . , 22 _l are formed and connected to a common ground line 25 through a through hole 24.
23 (23 ₁ ,…, 23 _o-1 , 23 _o ,…, 23 _l )
is the other electrode terminal of MRE21. MRE2
1. The electrode terminals 22 and 23 form a magnetic flux sensor section 30a surrounded by a dashed line. The area surrounded by the two-dot chain line is the padded area 40. Within the pad area 40, pads 26 (26 ₁ ,..., 2
6 _o-1 , 26 _o , ..., 26 _l ) are arranged. The pad 26 can be formed into a thick film to have a bump or beam lead structure, if necessary. 27 is a lead wire connecting the electrode terminal 23 and the pad 26, and the lead wire 27 (27 1 , 27 ₁ ,
..., 27 _o-1 , 27 _o , ..., 27 _l ) are formed. The electrode terminals 22, 23, lead wires 27, and pads 26 are formed by patterning in the same process after depositing a conductive thin film of Al, Au, Cu, or the like.

A wiring device for a multi-channel thin film magnetic head constructed as described above will be explained. The present invention reduces the track width of all channels to W as shown in FIG.
Then, the lead wires from the magnetic flux sensor section 30a can be wire bonded to the board 20.
When widening the lead wiring 27 to almost the full width, the lead wiring 27 is patterned optimally to make the channel resistance of all channels uniform.

First, l MREs 21 are arranged at a constant pitch U, and in FIG.
The tip line width d on the opposite side of 1 is the same as lead wiring 2.
The line width is the same as that of the straight line part of 7. In other words, the lead wiring 27 (27 ₁ , ..., 27 _o-1 , 2
7 _o , ..., 27 _l ) has a straight line width of d. The lead wiring 27 has an angle θ between the straight line portion and the straight line portion.
consists of a 45 degree or 135 degree diagonal line, and an inflection point between the straight line and the diagonal line (for example, channel n-
1, A and B, and channel n, C and D) change in the length direction of the straight portion by a constant difference for each channel. The line width S of the hatched portion is the same for all channels. The hatched part of the lead wiring 27 and the pad 26
For example, the side wires having inflection points A and C of the n-1 and n channels, respectively, are connected to pads 26 with a line width H that are parallel to the straight part of the lead wiring 27.
It intersects with the extended side lines of _o-1 and 26 _o at inflection points E and F, respectively. The other lateral line, which has one inflection point B, D, extends to the pad area 40 and intersects the other lateral line of the pad. The pads 26 are arranged with a line width H, a line spacing γ, and a pitch T (=H+γ).
The lead wiring 27 has an angle θ=135 degrees in the shaded portion as shown in 27 ₁ of the first channel, and θ changes to 45 degrees from a certain channel. This inflection channel varies depending on the formation position of the magnetic flux sensor portion 30a on the substrate 20, the total track width W, the number of channels, etc. Also,
The straight portion of the lead wire 27 (lead wire 27 _l in FIG. 1) of the channel having the longest distance between the electrode terminal 23 and the pad 26 may be omitted for the purpose of shortening the wire length. In the wiring structure as described above, in order to make the channel resistance of all channels (l channel in the case of Fig. 1) uniform, the lead wiring 27
The diagonal line width S is the straight line width d for all channels.
It should be multiplied by √2. At this time, the lead wiring of the adjacent channel, for example, the lead wiring 27 _o-1 ,
27 Straight line at _o , inflection points A, C and B of the shaded part,
The distance differences P and Q in the straight line length direction of D are both T-U. However, T and U are the arrangement pitches of the pad 26 and the magnetoresistive element 21, respectively. Further, the intersection E between the extended side line of the pad 26 and the side line of the lead wiring 27 is located at a distance of H-2d from the pad area 40.

This can be achieved by setting the straight line width of the lead wiring 27 to d', which is larger than the line width d of the electrode terminal 23, for the purpose of reducing the channel resistance value. In this case, the diagonal line width S' is √2 times d'.

FIG. 2 shows a second embodiment of the invention,
The common tangent line 25 in FIG. 1 is guided to the pads 31 and 26 in a pair, with the line width of the electrode terminals 28 and 23 at both ends of the MRE 21 not installed on the substrate 20 being d, respectively. This shows the channel. Compared to FIG. 1, each channel has an electrode terminal 28 and a lead wiring 29 connected thereto.
The wiring rules for the lead wirings 27 and 29 are the same as in the example shown in FIG. 1, although the pad 31 at the end thereof has been changed or added. That is, lead wiring 2
The diagonal line widths S of 7 and 29 are both √2 times the straight line width d. Adjacent channel lead wiring 27,
Inflection point at 29, e.g. lead wire 29 _o-1
The distance P between point A and point C in 29 _o is T-U. .
However, T is the pitch between each channel of the pad, in this case T=2H+2γ, and U is the arrangement pitch of the magnetoresistive elements 21. In this embodiment, the lead wiring 2 is also used for the purpose of reducing the channel resistance value.
This can be achieved by making the straight line width d' larger than the line width d of the electrode terminals 23 and 28, and the diagonal line width
S′ is √2 times d′.

FIG. 3 shows a third embodiment of the wiring device for a multi-channel thin film magnetic head according to the present invention.
In this figure, the read head is the same as the read head in FIG. 1 except for the thin film coil portion 30b, and the same parts are given the same numbers. The thin film coil section 30 has thin film coil elements 32 (32 ₁ , . . . , 3
2 _o-1 , 32 _o , . . . , 32 _l ) are formed into an l channel. The recording head of each channel has a substrate 20 as the lower magnetic layer and a magnetic pole 33 as the upper magnetic layer, and a conductive thin film coil element 32 is formed in an electrically insulated manner between both magnetic layers. The common ground line 25 formed in advance on the substrate 20 is connected to the thin film coil element 3 of each channel through a through hole 34 formed in an insulating layer on the common ground line 25.
It is connected to 2.

Lead wiring 2 for equalizing each channel resistance
The patterning for the straight line width and diagonal line width of 7 is the same as in the case of the reproducing head shown in FIG.

As described above, according to this embodiment, the resistance of each channel of the multi-channel can be made uniform by optimal patterning of the lead wiring, that is, by making the width of the diagonal line at 45 degrees or 135 degrees equal to √2 times the width of the straight line. Can be done. Further, by reducing the resistance of each channel, especially the resistance of the lead wiring, it is possible to widen the straight line width as long as the spacing between adjacent channels is allowed.

In each example, the angle formed by the straight line part and the diagonal line part of the lead wiring was set to 45 degrees or 135 degrees, and the line width ratio was set to √2, but other angles may be used, and in this case, Needless to say, the line width must be changed depending on the angle so that the resistance of each channel becomes uniform.

Effects of the Invention The present invention has the pitch spacing of the magnetic flux sensor portion or thin film coil portion formed in the same pattern in each channel as U, the pad pitch spacing for wire bonding as T, and connects the magnetic flux sensor of each channel and the pad. The basic structure of the lead wiring pattern is a combination of a straight line part and a diagonal line part inclined at a certain angle, the straight line width d of each channel is constant, the diagonal line width is set according to the inclination angle, and By setting the inflection point between the part and the shaded part, that is, the difference between adjacent channels in straight line length, to be T-U, the lead wiring resistance of each channel can be made uniform. Therefore, the drive current to each channel (the sense current in the MR read head and the write current in the write head) can be made constant without using a correction resistance element of an external drive circuit. This is particularly effective in reducing drive voltage. It is also possible to reduce the resistance by widening the straight line width d of the lead wiring within a range that allows spacing with adjacent tracks for practical purposes. It is possible to realize a multi-channel thin-film magnetic head that can be driven at a low voltage by reducing the resistance, and that can achieve a number of effects such as reducing thermal noise, especially in the reproduction head.

[Brief explanation of the drawing]

1 is a plan view of a wiring device for a multi-channel thin film magnetic head according to a first embodiment of the present invention; FIG.
3 is a plan view of the third embodiment, FIG. 4 is a schematic plan view for explaining the present invention, and FIG. 5 is a plan view of the main part of the second embodiment. FIG. 2 is a plan view of a wiring device for a channel thin film magnetic head. 20... Substrate, 21... Magnetoresistive element, 2
2, 23... Electrode terminal, 24, 34... Through hole, 25... Common ground line, 26, 31... Bump, 27... Lead wiring, 30a... Magnetic flux sensor section, 30b... Thin film coil section, 32... thin film coil element, 33... magnetic pole, 40... padded area.

Claims (1)

[Claims] 1. An element section consisting of magnetoresistive elements or thin film coil elements provided corresponding to the number of channels along the reproduction or recording track width along one edge of the substrate, and the other edge of the substrate. The portion includes bonding pad portions provided in accordance with the number of channels in the track width direction over approximately the width of the substrate, and a plurality of leads connecting the magnetoresistive element of each channel and the bonding pad portion. Basically, the lead wiring of each channel is configured by a combination of a straight part of the lead wiring and a diagonal part having a certain inclination angle with respect to the straight part. A multi-channel channel connected to the bonding pad section on the oblique side of the element section, and wherein the line width of the hatched section is determined so that the resistance value of each channel is the same. Wiring device for thin film magnetic head.