JPH0243245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a wiring device for a multi-channel thin film magnetic head that is compatible with high-density recording in a magnetic recording/reproducing device.

2. Description of the Related Art In recent magnetic recording and reproducing devices, thin film type recording and reproducing heads are being widely used as recording linear densities and track densities have significantly improved. Multichannel digital recording is rapidly progressing in magnetic tape devices for computers and compact cassette tape recorders for audio, with the aim of increasing density and quality. As a result, magnetic heads are strongly required to have narrower tracks and multiple channels, and thin film magnetic head technology to realize this has been improved significantly in recent years.

As the distance between channels becomes shorter as thin film magnetic heads become multi-channeled, the structure of lead wires becomes important for the wiring on the head chip, especially for the purpose of facilitating electrical connections with external circuits. In conventional lead line patterns, large deviations occur in electrical resistance values between channels, requiring correction for each channel using an external circuit. Until now, there has been no example of a thin film magnetic head that has been optimally designed with respect to the lead wire structure.

A conventional multi-channel thin film magnetic head wiring device will be described below with reference to the drawings.
Figure 5 shows an m-channel magnetoresistive magnetic head (hereinafter referred to as an MR head) used for reproduction.
I will explain. The MR head in Figure 5 shows an example of the arrangement of magnetoresistive elements (hereinafter referred to as MREs) and lead wire structures on a substrate.
Other components for the final head structure,
The final shape is omitted.

In FIG. 5, reference numeral 1 denotes a substrate, which is made of a ferromagnetic material such as Mn--Zn single crystal ferrite. Board 1
A first insulating layer (not shown) such as SiO ₂ is formed on top, and after a common ground conductor 6 is formed on this, a second insulating layer (not shown) such as SiO ₂ is deposited. be done. On this second insulating layer, MRE2 for m channels is patterned into the required shape and dimensions.
(2 ₁ ,..., 2 _o ,..., 2 _n ) are arranged.
MRE2 consists of a ferromagnetic thin film such as a Ni-Fe film that has uniaxial magnetic anisotropy. The total track width W is made up of m channels. MRE in each channel of MRE2 has electrode terminals 3 (3 ₁ ,..., 3 _o-1 , 3 _o ,
…, 3 _n ) and 4 (4 ₁ , …4 _o-1 , 4 _o , …, 4 _n )
are formed respectively. Inside the dashed line is the above-mentioned MRE 2 and electrode terminals 3 and 4 as the magnetic flux sensor part.
These components are collectively referred to as the magnetic flux sensor section 10.

Each terminal of the electrode terminal 3 is connected to a common ground line 6 through a respective through hole 5 formed in the second insulating layer.
It is connected to the. The area surrounded by the two-dot chain line is a pad area 11 for wire bonding, which forms a pair with each of the electrode terminals 3 of the magnetic flux sensor section 10, and connects the pads 7 (7 ₁ ,..., 7 _o-1 , 7 _o , ...,
_7n ) is formed. The pads 7 are arranged at constant pitch intervals over almost the entire width of the track in the track width direction on the substrate 1. Pads 6 ₁ and 6 ₂ of the common ground line 6 are also configured at both ends within the pad area 11 . The lead wire 8 connecting the magnetic flux sensor section 10 and the pad area 11 connects the electrode terminal 3 (3 ₁ ,...3 _o-1 , 3 _o ,..., 3 _n ) and the pad 7 (7 ₁ ,..., 7 ) in each channel. _o-1 , _7o ,..., _7n ), and is composed of each leader line ₈₁ ,... _8o-1 , _8o ,..., _8n .

Lead line 8 of each channel (8 ₁ ,..., 8 _o-1 ,
8 _o ,..., 8 _n ) is a straight line extending perpendicular to the MRE 2 between the electrode terminal 3 and the pad 7 as shown in FIG.
It is composed of a diagonal line having an angle θ=45° with this straight line. Note that this angle θ may be 135°. Assuming that the line width D of each pad is constant, the line width of the diagonal line portion of the leader line in the case of FIG. 5 is D/√2 (the line width of the straight line portion is d).

In the multi-channel thin-film magnetic head for high-density recording and reproducing configured as described above, it is strongly required to make the resistance of all channels uniform on the head chip and realize low-voltage driving in order to simplify the head drive circuit and reduce costs. Ru. Furthermore, low resistance is also required for the purpose of suppressing heat generation during recording and reproduction.

Problems to be Solved by the Invention However, in the structure of the conventional lead wire described above, the deviation in the resistance value of each channel is essentially large. If the pitch spacing of the pads 7, the pad width D, the line width d of the straight portion of the lead extraction line, and even the track pitch between each channel of the MRE 2 are all inappropriate, a resistance value deviation of each channel will occur. Conventionally, these series of optimal designs have not been performed, so for example, the track pitch of MRE2 is 80 μm, d = 17 μm, D = 100 μm distance between pads.
20 μm, the number of channels m = 20, and the distance between the magnetic flux sensor 10 and the pad area ₁₁ is approximately 2.7 mm. ₂₀ ), the resistance value ratio is approximately twice as high. Unevenness in channel resistance requires channel correction for uniformity using an external drive circuit, and as the number of channels increases, the correction process becomes more complicated and becomes a factor in fluctuations in reproduction output and recording level.

In view of the above-mentioned problems, the present invention provides a wiring device for a multi-channel thin-film magnetic head that can make the resistance of all channels uniform, and at the same time as lowering the resistance, it is easy to design the densest pattern and miniaturize the shape. This is what we provide.

Means for Solving the Problems In order to solve the above problems, the present invention connects the MR sensor part of the reproducing head or the thin film coil part of the recording head to the pad area for wire bonding, and the structure thereof is a straight line. The basic combination is a combination of a part and a shaded part with an angle of 45° or 135° with respect to the straight line, or a combination of a straight part and a shaded part of both 45° and 135°. If the line width is √2 times the line width of the straight part, and (2) the pad pitch in each channel and the interval between adjacent pitches in the straight part of the leader line are T and P', respectively, then the relationship T = 2P' is established. That's true.

Effects The present invention provides, among the above-mentioned configuration means, by making the diagonal line width of the leader line pattern shape √2 times the straight line width, so that the channel resistance over all channels becomes completely equal, and T = 2P'. The densest implementation can be achieved by the relationship. Further, by increasing the line width of the straight portions as much as possible by considering the pitch interval P' of the straight portions, the resistance value of each channel can be easily reduced. According to the configuration of the present invention, if film thickness distribution errors and line width errors across each channel are ignored in the lead wire manufacturing process, resistance value deviation between each channel is eliminated, and a resistance correction circuit is unnecessary. Energy consumption can be reduced to zero. In addition, the densest patterning reduces the head chip shape, which greatly contributes to the miniaturization of system equipment, as well as shortening the lead wire length.
This prevents deterioration of signal quality due to disturbance noise and stray capacitance, and enables good recording and reproduction over a wide band. Lower resistance makes it easier to drive MR playback heads and recording heads with thin film coils at low voltages.
Furthermore, it reduces thermal noise in the MR head.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a plan view showing the concept of the present invention, showing a magnetic tape device capable of reciprocating recording and reproducing. The figure shows the layout concept on the recording head or reproduction head chip in single-sided recording and reproduction, where the total tape width H is the total track width W for recording and reproduction, and the external circuits such as flexible wires and printed circuit boards. The relative relationship between the connecting member 60 and the connecting member 60 is shown. In FIG. 4, 20 is a head chip substrate (hereinafter referred to as a substrate), 30 is a thin film coil section in the case of a recording head, and a magnetic flux sensor section in the case of a reproducing head. 40 is a pad area for wire bonding, 27 is a main part of the present invention, and is a lead wire connecting the thin film coil section 30 (or magnetic flux sensor section) and the pad area 40, the number of which is equal to or twice the number of channels. be equivalent to. The pad area 40 extends over almost the entire width of the board 20 and is connected to the conductor 70 on the connecting member 60.
This facilitates bonding for each channel.

FIG. 1 mainly shows the lead line structure on a chip of a wiring device for a multi-channel thin film magnetic head for reproduction according to an embodiment of the present invention. Components for the final head structure are omitted and the final shape is not shown.

In FIG. 1, 20 is a highly permeable substrate made of Mn-Zn single crystal ferrite, Ni-Zn ferrite, etc., and a first insulating layer (not shown) made of SiO ₂ or the like is formed on this substrate 20. After the common ground line 25 for all channels is patterned, a second insulating layer (not shown), such as SiO ₂ , is deposited to form the through-holes 24 . On the second insulating layer, m MREs 21 (21 ₁ ,
21 ₂ ,..., 21 _n ) are arranged in the required shape and pitch. As is well known, the MRE 21 is made of a ferromagnetic thin film such as a Ni--Fe film having uniaxial magnetic anisotropy. The total track width W shown in FIG. 4 is obtained by m channels. The MRE in each channel of the MRE 21 has an electrode terminal 22 extending perpendicularly to the MRE.
(22 ₁ , 22 ₂ , ..., 22 _n ) and 23 (23 ₁ , 2
3 ₂ ,..., 23 _n ) are formed, respectively.
The electrode terminal 23 is connected to a common ground line 25 through a through hole 24 formed in the second insulating layer. The dot-dash dot area is mainly composed of the above-mentioned MRE 21 and the electrode terminals 22, 23, and is collectively referred to as the magnetic flux sensor section 30 as explained in FIG. The area surrounded by the two-dot chain line is a pad area 40 for connecting the head chip and an external circuit by wire bonding or the like. Within the pad area, pads 26 (2
6 ₁ ,..., 26 _n ) are arranged. Patsudo 26
If necessary, a thick film can be formed, and a bump or beam lead structure can also be formed. As a wiring group connecting the magnetic flux sensor section 30 and the pad area 40, a number of lead wires 27 (2
7 ₁ ,..., 27 _n ) are formed. Note that a pad for the common ground line 25 is also formed within the bump area 40. Electrode terminals 22 and 23, lead wire 2
7. In the manufacturing process of Pad 26 etc., Al,
After depositing a conductor thin film such as Au or Cu, it is patterned using the same process.

A wiring device for a multi-channel thin film magnetic head constructed as described above will be explained. The present invention is the fourth
As shown in the figure, when the track width of all channels is set to W and the lead wire from the magnetic flux sensor section 30 is expanded to almost the entire width of the board 20 to a size that allows connection to an external circuit such as wire bonding, the lead wire 27 is optimized. The purpose is to make the channel resistance of all channels uniform by patterning, and to miniaturize the head chip by forming the most dense structure.

In FIG. 1, m MREs 21 are arranged at a constant pitch P. The shape, film thickness, etc. of the electrode terminals 22 and 23 in the magnetic flux sensor section 30 and the pad 26 in the pad area 40 are the same in all channels. The lead line 27 of each channel consists of a straight part with a line width d and a diagonal part with a line width S, and the inclination angle of the diagonal part is θ=45° or 135° (only 45° in the case of Fig. 1). be. The pitch between the straight section and the adjacent channel is P', and in the configuration example shown in Figure 1,
It has the same pitch as MRE21 (P'=P). The distance between the lines is r. In other words, P'=d+r. One end of the straight portion of the lead wire 27 is connected to the electrode terminal 22, and one end of the diagonal line portion is connected to the pad 26, respectively.
The line width of the pads 26 is D, and the distance between the pads is G. Therefore, the pads of each channel are aligned in the track width direction at a pitch of T=D+G. The state of connection between the hatched part of the lead line 27 of each channel and the pad 26 will be explained, for example, in the third channel.The side line AB intersects with the extension line of one side line EC of the pad ₂₆₃ at B. Let the distance between BC be ΔX. The other diagonally shaded side line FJ intersects the pad side line KJ at J on the boundary line of the pad area 40.

Here, the following conditions are set for the leader line pattern as described above.

(1) Set S=√2d between the line width d of the straight line part and the line width S of the diagonal line part in each channel of the leader line 27.

(2) The distance ΔX between the intersection B of the diagonally shaded side line AB and the pad side line EC and the pad area 40 is ΔX = D-2d
shall be.

(3) Straight line pitch P' of leader line 27 and pad 26
T=2P' is satisfied between the pitch T of (therefore, T=2P is also satisfied).

Among the above condition settings, the channel resistance of all channels can be made equal from conditions (1) and (2), and from the condition (3), the inflection point between the straight part and the diagonal part of the leader line, for example, the In 3 channels, all points A and F are aligned on a straight line with α=135°. This means that the densest pattern with high space utilization efficiency (particularly in the track width direction) can be realized. Also, the amount of change in the length of the straight section between adjacent channels is T-
becomes P′.

For example, P'=80μm, d=40μm, ΔX=40μm
Then, D = 120 μm, G = 40 μm, r
= 40 μm and S = 56.6 μm are determined. In addition, when increasing the distance between lines in the diagonal areas or the spacing between pads during the mounting process, pattern design can be easily done by controlling ΔX. For example, P'=80μm, d=40μ
m, ΔX=0, then D=80μm, G=80μm, r
= 40 μm, S = 56.6 μm.

In order to reduce the resistance value of each channel of the lead wire, it is necessary to increase the line width d of the straight line part as much as possible in the mounting process while satisfying the three conditions (1) to (3) above, or shorten its length. Hidden. As shown in FIG. 1, it is possible to make the straight portion of the m-th channel zero, and the size of the head chip can be reduced.

As the number of channels increases and m′ (m′>m), the angle of inclination of the shaded area is not necessarily all θ = 45° as shown in Figure 1, but θ from the first channel to a certain channel is 135° (as shown in Fig. 1). α = 45°), and after that
Setting θ=45° up to the m′ channel means expanding the degree of freedom in design, regardless of the number of channels, from the purpose of optimal pattern design of the present invention.

FIG. 2 shows the electrode terminals 22 (22 ₁ , . . . , 22 _n ) and 28 (28 ₁ , .
28 _n ) are both lead lines 27 (27 ₁ , 27 1 ,
..., 27 _n ) and 29 (29 ₁ , ..., 29 _n ) and are led to the pad area 40 in terms of an electric circuit, indicating the first, second, and third channels. . In other words, MRE2 of each channel
This type has two lead lines in one part. Pads 31 (31 ₁ , . . . , 31 _n ) are formed in the pad area 40 in correspondence with the lead lines 29.
The optimal design of the leader line pattern in this case is based on the same idea as the structure shown in FIG. 1, and is formed by a straight line part and a diagonal line part with an inclination angle θ=45° or 135°. Let the array pitch of MRE21 be P, and the pad 2
As shown in Figure 2, the arrangement pitch of each of pads 6 and 31 is T, the pad width is D, and the distance between pads is G.
(Therefore, T=D+G). Lead line 26,2
In the example shown in FIG. 2, the connection between the diagonal line part 9 and the pads 26 and 31 is made by the side line AB of the diagonal line part of the leader line 29.
and the extension line of the side line EC of the bump 31 intersect at point B, and the distance between BC becomes ΔX. The other side lines FJ and KJ intersect at point J on the boundary of the padded area 40. Lead lines 27 and 29 of each channel
The line width of the straight line part is d, and the line width of the diagonal line part is S.

The following conditions are set for the above leader line pattern.

(1) Create the relationship S=√2d between the line width d of the straight line and the line width S of the diagonal line in each channel.

(2) Let ΔX at one leader line (the leader line 29 in FIG. 2) of each channel be ΔX=D−2d.

(3) The distances between the straight parts of the lead lines 27 and 29 are all set to the same r.

(4) The pitch P'=d+r of the straight line section is set to 1/2 of the arrangement pitch P of the MRE21.

(5) Set the pitch P′ of the straight part to the pitch T of the pads.
1/2 (therefore, P'=1/2P=1/2T).

Among the above condition settings, under conditions (1) and (2), the sum of the resistance values of the two lead wires 27 and 29 of each channel becomes equal in all channels. From the conditions (3), (4), and (5), all the inflection points between the straight and diagonal parts of the leader line are aligned on a straight line at α=135°. Therefore, the densest pattern with the highest space utilization efficiency can be achieved. Furthermore, the amount of change in length of the adjacent straight section is T-
becomes P′.

For example, if P′ = 40 μm, d = 20 μm, ΔX = 20 μm, D = 60 μm, G = 20 μm, r = 20 μm, S =
It becomes 28.3μm.

As with the configuration shown in FIG. 1, it is possible to achieve optimal patterning by controlling the straight line width d, length ΔX, etc. at a level that can be realized in the mounting process. Also, when the number of channels increases, the leader line 27, 2 of θ = 135°
It is also the same as the configuration shown in FIG. 1 that an optimized pattern can be created by introducing the hatched portion 9.

FIG. 3 shows the present invention applied to a magnetic induction type multi-channel thin film recording head or a recording/reproducing head. In this figure, the configuration is the same as that of the reproducing head in FIG. 1 except for the thin film coil section 30, and the same parts are given the same numbers. Thin film coil section 30
is the track pitch P and the thin film coil element 32 (32
₁ , 32 ₂ , . . . , 32 _n ) are arranged for m channels. The recording head of each channel has a lower magnetic layer as a substrate 20 and an upper magnetic layer as a magnetic pole 33.
A conductive thin film coil element 32 is patterned in an electrically insulated manner between both magnetic layers. A first insulating layer (not shown) is deposited on the substrate 20 and a common ground line 25 is formed thereon. A through hole 34 is provided on this common ground line 25.
There is a second insulating layer having a through hole 34.
One end of the thin film coil element 32 of each channel is connected to the common ground line 25 through the channel.

The pattern of the lead line 27 in the configuration shown in FIG. 3 has an inclination angle of θ
= 135°, and the inclination angle of each channel after that is θ =
This is an example in which the angle is 45°. The pattern design conditions for the leader line 27 are the same as those for the reproduction head shown in FIG.

As described above, the optimal design conditions for the leader line are established regardless of the type of recording/reproducing head and regardless of the number of channels.

Effect of the invention The effects of the present invention are summarized below.

(1) The voltage resistance value of each channel on the head chip of a multi-channel thin film magnetic head becomes equal over all tracks. As a result, electrical resistance correction means for each track using an external circuit becomes unnecessary, and manufacturing costs can be significantly reduced.

(2) Since the external resistance correction circuit can be removed, the drive voltage can be lowered.

(3) Since the leader line consists of only a straight line and a diagonal line at an angle of 45° or 135°, photomask design is extremely easy.

(4) The intersections of the straight line portion and the diagonal line portion of the leader line are arranged on a straight line with an inclination angle of 45° or 135° across all channels, resulting in the densest leader line pattern. Therefore, the area occupied by the lead wire on the chip can be reduced, and the head chip can be made smaller. Furthermore, as the lead wire is shortened, it is less susceptible to external noise and stray capacitance, and high-quality recording and playback becomes possible.

(5) While ensuring uniform electrical resistance of all channels, there is a large degree of freedom in reducing the resistance value, making it possible to design optimally according to the capabilities of the manufacturing process.

(6) As manufacturing capacity improves, it is possible to reduce the resistance by reducing the spacing between adjacent straight parts and increasing the line width of the straight part of the lead wire. This reduction in resistance has a significant effect on low voltage drive and thermal noise reduction.

[Brief explanation of drawings]

1 and 2 are plan views of a wiring device for a multi-channel thin film magnetic head according to an embodiment of the present invention;
FIG. 3 is a plan view of a wiring device for a multi-channel thin film recording head as another embodiment, FIG. 4 is a plan view for explaining the concept of the present invention, and FIG. 5 is a plan view of a conventional multi-channel thin film reproducing head. FIG. 3 is a plan view of the wiring device. 20... Substrate, 21... Magnetoresistive element, 2
2, 23... Electrode terminal, 24, 34... Through hole, 25... Common ground wire, 26, 31... Pad, 27... Lead wire, 30... Magnetic flux sensor section,
32... Thin film coil element, 33... Magnetic pole,
40... Pad area, 60... Connection member, 70
...Conductor, 80...Magnetic tape.

Claims (1)

[Scope of Claims] 1. A number of channels of magnetoresistive elements for reproduction or thin film coil elements for recording and reproduction are arranged along one edge of the substrate at intervals of pitch P in the track width direction; Along the other edge, in parallel with the direction in which the elements are arranged, bonding pads corresponding to the number of channels are arranged at intervals of pad line width D and pitch T over almost the entire width of the substrate, and each channel has the above bonding pads. It has a plurality of lead line groups connecting the element and the pad part, and each of the lead lines has a straight part with a line width d and an inclination angle of 45 degrees with respect to the straight part.
Basically, it is combined with the shaded part of 135 degrees,
The line width of the diagonal line part where one end connects to the pad part is √2d, and only one side line constituting the line width of the diagonal line part is on the extension line of one side line of the corresponding pad. If the number of lead wires intersecting at a distance of 2d and extending from each of the above elements is one with respect to the arrangement pitch P′ of the straight line part of the lead wires, then
P′=P=T/2, in the case of two wires, P′=P/2=T/2 is satisfied, and the amount of change in length of the adjacent straight part of the leader line is T−P′. A wiring device for a multi-channel thin film magnetic head.