JP6145975B2 - Suspension board, suspension, suspension with head, and hard disk drive - Google Patents

Description

  The present invention mainly relates to a suspension board on which a magnetic head slider used for a hard disk drive (HDD) and writing and reading data to and from a disk storing data is mounted.

  In recent years, due to the spread of the Internet and the like, there has been a demand for an increase in the amount of information processing of personal computers and an increase in information processing speed, and along with this, the capacity of hard disk drives (HDD) incorporated in personal computers has increased. Increasing information transmission speed is required.

In general, a hard disk drive (HDD) includes a suspension substrate on which a magnetic head slider for writing and reading data to and from a disk storing data is mounted.
The suspension substrate generally includes a metal support substrate having a spring property, a base insulating layer formed on the metal support substrate, and a plurality of wirings formed on the base insulating layer. ing.

  As a method for forming wiring for the above-described suspension board, a subtractive method and a semi-additive method that have been conventionally used for manufacturing flexible printed wiring boards are known (Patent Document 1).

The subtractive method is a method of forming wiring mainly by etching. For example, as shown in FIG. 12, a laminated body in which a metal support substrate 111, a base insulating layer 112, and a wiring material layer 114 are sequentially formed. (FIG. 12A), a resist pattern 117 is formed on the wiring material layer 114 (FIG. 12B), and the wiring material layer 114 exposed from the resist pattern 117 is etched ( In FIG. 12C, the resist pattern 117 is peeled and removed (FIG. 12D) to form desired wirings (for example, 114a and 114b).
In order to prevent deterioration due to corrosion or the like, the formed wiring is usually covered with a cover insulating layer 115 except for a portion to be a terminal portion as shown in FIG.

On the other hand, the semi-additive method is a method of forming wiring mainly by plating. For example, as shown in FIG. 13, a base insulating layer 212 is formed on a metal support substrate 211 (FIG. 13A )), A resist pattern 217 is formed on the insulating base layer 212 (FIG. 13B), and wiring (eg, 214a and 214b) is formed on the insulating base layer 212 exposed from the resist pattern 217. After the metal to be formed is plated to a required thickness (FIG. 13C), the resist pattern 217 is peeled and removed (FIG. 13D) to form desired wirings (for example, 214a and 214b). It is a method to do.
In this case as well, the formed wiring is usually covered with a cover insulating layer 215 except for a portion to be a terminal portion as shown in FIG. 13E in order to prevent deterioration due to corrosion or the like.

  And, the cross-sectional shape of the wiring of the conventional suspension board manufactured by using each of the above methods is, for example, the width (W102) of the wiring upper surface as shown in FIG. 14 (a) or (b). It has a substantially trapezoidal shape smaller than the width (W101) of the wiring bottom surface or a rectangular shape in which the width (W102) of the wiring top surface is the same as the width (W101) of the wiring bottom surface.

Conventionally, a rolled copper foil or the like has been used as the wiring material layer 114 in the subtractive method (FIG. 12). However, in recent years, the wiring material layer 114 is mainly used for miniaturization of wiring. It is becoming electrolytic copper formed by electrolytic plating, and a thin film conductor material layer for plating power supply may be provided between the base insulating layer 112 and the wiring material layer 114 in some cases. In this case, after the wiring is formed, an unnecessary portion of the thin film conductor material layer exposed between the wirings is removed.
Also in the semi-additive method (FIG. 13), the step of forming the base insulating layer 212 (FIG. 13A) and the step of forming the resist pattern 217 (FIG. 13) in order to form wiring by plating. 13 (b)), a step of forming a thin film conductor material layer for plating power supply on the insulating base layer 212 may be performed. Also in this case, after the wiring is formed, an unnecessary portion of the thin film conductor material layer exposed between the wirings is removed.

JP 2006-24521 A

  Some of the wiring of the suspension substrate as described above (for example, write wiring and read wiring) include a first signal wiring and a second signal wiring electrically independent of the first signal wiring. A differential impedance which is a characteristic impedance of a differential transmission line as a distributed constant circuit exists between the pair of differential wirings.

The above-mentioned differential impedance is required to be reduced from the viewpoint of impedance matching as the magnetic head and external circuit are reduced in impedance. As a method for achieving the low impedance as described above, for example, there is a method of reducing the distance between two wires constituting the pair of differential wires.
However, in the conventional suspension substrate, when the distance between the wirings is reduced as described above, the problem of ion migration tends to occur. The ion migration problem will be described below.

As described above, the cross-sectional shape of the wiring of the conventional suspension board is substantially the same as shown in FIG. 14A or 14B, in which the width (W102) of the upper surface of the wiring is smaller than the width (W101) of the lower surface of the wiring. It has a trapezoidal shape or a rectangular shape in which the width (W102) of the wiring top surface is the same as the width (W101) of the wiring bottom surface. Therefore, in the conventional suspension board, the distance between the bottom surfaces of the two wires is equal to the shortest distance between the two wires.
More specifically, for example, as shown in FIG. 15A, when the cross-sectional shape of the two wirings 114a and 114b is a substantially trapezoidal shape in which the width of the wiring upper surface is smaller than the width of the wiring bottom surface. The distance (S100) between the bottom surface of the wiring 114a and the bottom surface of the wiring 114b is the closest distance in the interval between the wiring 114a and the wiring 114b.
Further, as shown in FIG. 15B, when the cross-sectional shape of the two wirings 214a and 214b is a rectangular shape in which the width of the wiring upper surface is the same as the width of the wiring bottom surface, the wiring 214a and the wiring 214b The distance between them is the same distance (S200) from the upper surface of the wiring to the lower surface of the wiring. That is, the distance between the bottom surface of the wiring 214a and the bottom surface of the wiring 214b is also a distance (S200), and this distance (S200) is equal to the closest distance in the interval between the wiring 214a and the wiring 214b.

Here, a wiring structure as described above (a pair of differential wiring structures in which electrical signals transmitted to the respective wirings are in opposite phases to each other, that is, positive and negative electrodes are arranged on the insulating layer to face each other. As a problem that is likely to occur in such a structure, there is an electrical short circuit due to ion migration. Note that ion migration is a phenomenon in which a metal component moves across or inside a non-metallic medium due to the influence of an electric field.
This ion migration tends to occur at the interface of the insulating layer. Therefore, for example, as shown in FIG. 15A and FIG. 15B, two wirings constituting a pair of differential wirings are formed on the base insulating layer at positions close to each other, In the suspension substrate having a structure in which the distance between the bottom surfaces of the two wires is equal to the shortest distance between the two wires, the interface of the base insulating layer between the two wires ( For example, the ion migration is likely to occur in the insulating base layer 112 and the insulating cover layer 115 shown in FIG.

  Therefore, in the conventional suspension substrate, the distance between the pair of differential wirings in the portion close to the interface of the base insulating layer where ion migration is likely to occur is the shortest, and the pair of differential wirings is reduced in order to reduce the impedance. When the distance between the two wires constituting the differential wire is reduced, there is a problem that an electrical short circuit due to the ion migration is likely to occur between the wires.

  The present invention has been made in view of the above circumstances, and reduces differential impedance while suppressing the occurrence of an electrical short circuit due to ion migration between two wires constituting a pair of differential wires. An object of the present invention is to provide a suspension substrate, a suspension, a suspension with a head, and a hard disk drive that can be used.

  As a result of various studies, the inventor has found that the above problem can be solved by making the wiring of the suspension substrate a wiring having a portion having a width larger than the width of the bottom surface in the thickness direction. Is completed.

That is, the invention according to claim 1 of the present invention is a suspension substrate in which a plurality of wirings are formed on a base insulating layer formed on a metal supporting substrate , and the cover is formed on the base insulating layer. An insulating layer is formed, the wiring includes a portion having a width larger than the width of the bottom surface in the thickness direction, and the plurality of wirings are electrically connected to each other with a plurality of first signal wirings A plurality of second signal wirings that are electrically independent of the first signal wirings and electrically connected to each other, and arranged in parallel alternately in a plane, and the width of the bottom surface is the width of the portion with the largest width between the bottom surface from the top surface of the wiring, Ri 10% to 40% less width der, the portion with the largest width between the bottom surface from the top surface of the wiring Present in the body of the wiring, and the bottom of the wiring From the portion having the largest width of the trunk portion of the wiring to the upper surface of the wiring from the portion having the largest width of the trunk portion of the wiring. A suspension substrate characterized in that the wiring width gradually decreases .

The invention according to claim 2 of the present invention is the suspension substrate according to claim 1 , wherein the insulating cover layer is formed on the wiring.

According to a third aspect of the present invention, in the metal support substrate, the first signal wiring and the first signal wiring are disposed at a position overlapping with a region where the first signal wiring and the second signal wiring are arranged. than the width of were arranged and two signal wiring region is suspension substrate according to claim 1 or claim 2, characterized in that the opening is formed with a large opening width.

According to a fourth aspect of the present invention, there is provided a suspension comprising the suspension substrate according to any one of the first to third aspects and a load beam.

According to a fifth aspect of the present invention, there is provided a suspension with a head comprising the suspension according to the fourth aspect and a magnetic head slider mounted on the suspension.

According to a sixth aspect of the present invention, there is provided a hard disk drive including the suspension with a head according to the fifth aspect.

In the suspension substrate of the present invention, the differential impedance can be reduced while suppressing the occurrence of an electrical short circuit due to ion migration.
By using the suspension substrate of the present invention, it is possible to obtain a highly reliable suspension, a suspension with a head, and a hard disk drive that have a low impedance and suppress the occurrence of a short circuit.

It is a schematic plan view showing an example of a suspension substrate according to the present invention. It is AA sectional drawing of the area | region R in FIG. It is explanatory drawing which shows the example of the cross-sectional shape of the wiring of the board | substrate for suspensions concerning this invention. It is a schematic sectional drawing for demonstrating the difference between the suspension board | substrate which concerns on this invention, and the conventional suspension board | substrate. It is a schematic plan view which shows the other example of the board | substrate for suspensions concerning this invention. It is explanatory drawing which shows the circuit structure of the interleave wiring of the board | substrate for suspension shown in FIG.5 (b). It is a typical process figure showing an example of a manufacturing method of a substrate for suspensions concerning the present invention. FIG. 8 is a schematic process diagram illustrating an example of a method for manufacturing a suspension substrate according to the present invention following FIG. 7. 1 is a schematic plan view showing an example of a suspension according to the present invention. It is a schematic plan view showing an example of a suspension with a head according to the present invention. 1 is a schematic perspective view showing an example of a hard disk drive according to the present invention. It is a typical process figure showing an example of the manufacturing method of the conventional suspension board. It is a typical process figure showing other examples of the manufacturing method of the conventional suspension board. It is explanatory drawing which shows the example of the cross-sectional shape of the wiring of the conventional board | substrate for suspensions. It is a schematic sectional drawing which shows the example of the conventional board | substrate for suspensions.

  Hereinafter, the suspension substrate, suspension, suspension with head, and hard disk drive of the present invention will be described in detail.

[Suspension substrate]
First, the planar configuration of the suspension substrate of the present invention will be described.
FIG. 1 is a schematic plan view showing an example of a suspension substrate according to the present invention.
As shown in FIG. 1, a suspension substrate 1 according to the present invention has a tongue portion 2 for mounting a magnetic head slider at a tip portion, and is connected to an external reading circuit or writing circuit at a tail side end portion. A wiring group 4 including a write wiring for electrically connecting the magnetic head and the write circuit between the tongue portion 2 and the connection terminal portion 3; The wiring group 5 includes a reading wiring that electrically connects the magnetic head and the reading circuit.

  Here, the wiring group 4 including the write wiring and the wiring group 5 including the reading wiring are respectively used for the suspension substrate in order to avoid mutual electrical influence as much as possible and to maintain the mechanical balance of the suspension substrate. Are arranged along both outer edges in the longitudinal direction.

  Note that the arrangement relationship between the wiring group 4 including the write wiring and the wiring group 5 including the reading wiring in FIG. 1 is an example, and may be another arrangement relationship. For example, the wiring group 5 including the read wiring is disposed at the position of the wiring group 4 including the write wiring in FIG. 1, and the wiring group 4 including the write wiring is disposed at the position of the wiring group 5 including the read wiring. It may be provided.

Next, a cross-sectional configuration of the suspension substrate according to the present invention will be described.
The suspension substrate according to the present invention is a suspension substrate in which a plurality of wirings are formed on a base insulating layer formed on a metal supporting substrate, and the wirings are larger than the width of the bottom surface in the thickness direction. A portion having a large width is provided. Here, in the present invention, the “bottom surface” of the wiring refers to the surface of the wiring on the base insulating layer side, and the “top surface” of the wiring refers to the surface of the wiring on the side opposite to the base insulating layer side.
With such a configuration, in the suspension substrate according to the present invention, it is possible to suppress the occurrence of an electrical short circuit due to ion migration between the two wires constituting the pair of differential wires. The differential impedance can be reduced.
Hereinafter, the relationship between the configuration and effects of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a cross-sectional view showing a configuration example of the suspension substrate according to the present invention, and is a cross-sectional view taken along the line AA of the region R in FIG.
For example, in the suspension substrate 10 of the embodiment shown in FIG. 2, the wiring 14a and the wiring 14b are formed on the base insulating layer 12 formed on the metal support substrate 11. And both the wiring 14a and the wiring 14b are provided with the part which has a width | variety larger than the width | variety of a bottom face in the thickness direction.
Note that the wiring 14a and the wiring 14b in the present embodiment are a pair of configurations in which a first signal wiring and a second signal wiring electrically independent of the first signal wiring are arranged in parallel in a plane. Differential wiring.

As described above, the wiring according to the present invention includes a portion having a width larger than the width of the bottom surface in the thickness direction. In other words, the wiring according to the present invention only needs to have a portion wider than the bottom surface in a portion different from the bottom surface between the bottom surface and the top surface.
An example of a typical cross-sectional shape of the wiring having the above configuration is shown in FIG.
Here, FIGS. 3A and 3B exemplify a form in which the portion having the width (W2) larger than the width (W1) of the bottom surface is the upper surface of the wiring in the thickness direction of the wiring 14a. 3 (c) exemplifies a form in which a portion having a width (W2) larger than the width (W1) of the bottom surface exists in the body portion (between the top surface and the bottom surface) in the thickness direction of the wiring 14a. It is.

  More specifically, for example, in the form shown in FIG. 3A, the wiring width between the bottom surface and the top surface of the wiring 14a from the height H1 gradually increases from W1 to W2, but the height The wiring width from H1 to the height position (ie, the upper surface) obtained by adding H2 is substantially the same (W2). On the other hand, in the form shown in FIG. 3B, the wiring width continuously increases from W1 to W2 from the bottom surface to the top surface of the wiring 14a.

  In FIG. 3A, for ease of explanation, the cross-sectional shape of the wiring 14a is represented by a polygon having a linear outer shape, but the present invention is not limited to this form, and the wiring Between the bottom surface and the top surface, the wiring width changes significantly so as to increase to a certain height position (H1 shown in FIG. 3A). Includes a form in which even if there is a change in the wiring width, the degree of the change is smaller than the previous change (change from the bottom surface of the wiring to a certain height position).

On the other hand, in the embodiment shown in FIG. 3C, the wiring width between the bottom surface and the top surface of the wiring 14a from the height H3 gradually increases from W1 to W2, but the height H3 is further increased from the height H3. The wiring width between the added height position (that is, the upper surface) gradually decreases from W2 to W3.
In the example shown in FIG. 3C, the top surface wiring width W3 is larger than the bottom surface wiring width W1, but the present invention is not limited to this mode, and the top surface wiring width W3 is The form may be smaller than the wiring width W1 on the bottom surface.

Next, the effect of the suspension substrate according to the present invention having the above-described form of wiring will be described with reference to FIG.
4A and 4B are schematic cross-sectional views for explaining the difference between the suspension substrate according to the present invention and the conventional suspension substrate. FIG. 4A is a suspension substrate according to the present invention, and FIG. Each of the suspension substrates is shown. In FIG. 4, the description of the metal support substrate and the cover insulating layer is omitted for ease of explanation.

  For example, as in the example shown in FIG. 4B, in the conventional suspension substrate 100, the wiring 114a and the wiring 114b constituting the pair of differential wirings are arranged at the design pitch (the distance between the center lines of the respective wirings). ) Becomes P100, the shortest distance between the wiring 114a and the wiring 114b is the distance S100 between the bottom surfaces of the wirings. That is, the wiring 114a and the wiring 114b are closest to each other on the bottom surface.

  On the other hand, the wiring of the suspension substrate according to the present invention includes a portion having a width larger than the width of the bottom surface in the thickness direction. Therefore, for example, in the suspension substrate 10 according to the present invention having the configuration shown in FIG. When the distance is formed to be P1, the shortest distance between the wiring 14a and the wiring 14b is shorter than the distance S1 between the bottom surfaces of the wirings (in FIG. 4A, the shortest distance is Distance S2). That is, the wiring 14a and the wiring 14b are closest to each other at a portion different from the bottom surface.

Therefore, for example, even if the design pitch P1 and the design pitch P100 are the same, the distance S1 between the bottom surfaces of the wiring according to the present invention is larger than the distance S100 between the bottom surfaces of the conventional wiring. Become. That is, in the present invention, the distance between the wirings can be made larger than the conventional distance at the interface of the insulating layer where the ion migration is likely to occur (the surface of the base insulating layer 12 in FIG. 4A).
Therefore, in the present invention, even if the design pitch between the pair of differential wirings (the distance between the center lines of each wiring) is reduced in order to reduce the impedance, the occurrence of the ion migration between the wirings is suppressed. can do.
In other words, the suspension substrate according to the present invention can reduce the differential impedance while suppressing the occurrence of an electrical short circuit due to the ion migration.

Here, in the suspension substrate according to the present invention, a cover insulating layer is preferably formed on the wiring and the base insulating layer.
This is to prevent the wiring from deteriorating due to corrosion or the like. Moreover, it is because the capacity | capacitance of the capacitive coupling between wiring can also be enlarged by burying between both wiring with a cover insulating layer.
For example, in the suspension substrate 10 according to the embodiment of the present invention shown in FIG. 2, the insulating cover layer 15 is formed on the wirings 14 a and 14 b and the insulating base layer 12.

Further, thin film conductors 13a and 13b may be formed between the wirings 14a and 14b and the insulating base layer 12 as shown in FIG.
For example, when the wirings 14a and 14b are formed by an electrolytic plating method, a thin film conductor layer is formed as a seed layer on the base insulating layer 12, and a portion exposed from the wiring of the thin film conductor layer after the wiring is formed. Is removed by etching, but the portion of the thin film conductor layer under the wiring remains. The portions of the thin film conductor layer that remain are, for example, the thin film conductors 13a and 13b.
The thin film conductors 13a and 13b are formed, for example, by sputtering, and the material thereof is, for example, a metal containing Cu (copper), and the thickness thereof is, for example, in the range of 0.05 μm to 2.0 μm.

  In the above description, the case where the wiring of the suspension substrate according to the present invention is a differential wiring is described as an example in which the effect of preventing a short circuit is particularly significant, but the present invention is not limited to this. The suspension substrate according to the present invention can suppress the occurrence of ion migration at the interface of the base insulating layer by providing the wiring having a portion having a width larger than the width of the bottom surface in the thickness direction. Anything is acceptable.

On the other hand, the wiring of the suspension substrate according to the present invention may constitute an interleave wiring. That is, in the suspension board according to the present invention, the plurality of wirings are electrically connected to each other, and the plurality of first signal wirings electrically connected to each other are electrically independent from each other. A plurality of the second signal wirings arranged may be alternately arranged in a plane.
Also in this case, the differential impedance can be further reduced while suppressing the occurrence of an electrical short circuit due to ion migration.

For example, as shown in FIG. 5B, the suspension board according to the present invention includes two first signal wires (for example, 34a and 34c) and two second signal wires (for example, 34b). 34d) may be alternately arranged on the base insulating layer 12 in a planar manner.
Although not shown in FIG. 5B, the wiring 34a and the wiring 34c are electrically connected to each other, and the wiring 34b and the wiring 34d are electrically connected to each other. The first signal wiring constituted by the wiring 34a and the wiring 34c and the second signal wiring constituted by the wiring 34b and the wiring 34d are electrically independent from each other. The relationship of the electrical connection of each wiring will be described next with reference to FIG.

FIG. 6 is an explanatory diagram showing a circuit configuration of interleave wiring of the suspension substrate shown in FIG.
As shown in FIG. 6, the interleave wiring 40 is a first signal wiring that electrically connects the connection terminal 41a and the connection terminal 41c, and a second signal wiring that electrically connects the connection terminal 41b and the connection terminal 41d. The first signal wiring is branched into a wiring 34a and a wiring 34c at a branch point 42a, and similarly, the second signal wiring is a wiring 34b and a wiring 34d at a branch point 42b. Each of the branched wirings is arranged in parallel in the order of 34a, 34b, 34c, 34d from the left end of the drawing so that the wirings for transmitting electrical signals with opposite phases are adjacent to each other.
The wirings 34a and 34c through which electrical signals of the same phase are transmitted are electrically connected by the connection line 44a via the connection vias 43a and 43b, respectively. Similarly, the wirings 43b and 43d are connected to each other. The connection line 44b is electrically connected via the vias 43c and 43d.
For example, in the present invention, the connection vias 43a, 43b, 43c, and 43d are formed in the base insulating layer 12 shown in FIG. 5B, and the connection lines 44a and 44b are formed in the openings 36 of the metal support substrate 31. Can be formed.
As described above, the interleave wiring can reduce the differential impedance more than a normal differential wiring having no branch structure by branching and alternately arranging a pair of differential wirings.

In the present invention, the first signal wiring and the second signal wiring are arranged on the metal supporting board at a position overlapping with a region where the first signal wiring and the second signal wiring are arranged. An opening having an opening width larger than the width of the region may be formed.
This is to prevent an increase in transmission loss of high-frequency signals due to the formation of inductive or capacitive coupling between the wiring and the underlying metal support substrate.

For example, in the suspension substrate 20 according to the embodiment of the present invention shown in FIG. 5A, the wiring 14a and the wiring 14b are disposed on the metal support substrate 21 at a position overlapping the region where the wiring 14a and the wiring 14b are arranged. An opening 26 having an opening width larger than the width of the region where the two are arranged is formed.
The “width of the region in which the first signal wiring and the second signal wiring are arranged” is a direction perpendicular to the longitudinal direction in which the first signal wiring and the second signal wiring are arranged. For example, in FIG. 5A, the length from the left end of the bottom surface of the wiring 14a on the drawing to the right end of the wiring 14b is indicated.

Similarly, in the suspension substrate 30 according to the present invention of the form shown in FIG. 5B, the metal support substrate 31 has wirings 34a to 34d at positions overlapping the regions where the wirings 34a to 34d are arranged. An opening 36 having an opening width larger than the width of the region where the elements are arranged is formed.
The “width of the region in which the first signal wiring and the second signal wiring are arranged” is a direction perpendicular to the longitudinal direction in which the first signal wiring and the second signal wiring are arranged. For example, in FIG. 5B, the length from the left end of the bottom surface of the wiring 34a on the drawing to the right end of the wiring 34d is indicated.

  Next, each member constituting the suspension substrate of the present invention will be described.

[Metal support substrate]
The material for the metal support substrate according to the present invention is not particularly limited as long as it functions as a support for the suspension substrate and has a desired spring property. For example, stainless steel can be used. .
For example, the thickness of the metal supporting substrate is preferably in the range of 10 μm to 30 μm, and more preferably in the range of 15 μm to 25 μm.

[Base insulation layer]
The insulating base layer according to the present invention is formed on the surface of the metal support substrate, and electrically insulates each wiring formed on the insulating base layer from the metal support substrate.
The material of the base insulating layer is not particularly limited as long as it has a desired insulating property and dielectric constant, and examples thereof include polyimide. The material of the base insulating layer may be a photosensitive material or a non-photosensitive material. The thickness of the base insulating layer is, for example, in the range of 5 μm to 30 μm.

[wiring]
The wiring material according to the present invention is not particularly limited as long as it has a desired conductivity, and examples thereof include copper (Cu). When each wiring is exposed, a protective plating layer of nickel (Ni) or gold (Au) may be formed on the surface thereof.

  For example, the thickness of the wiring is preferably in the range of 3 μm to 18 μm, and more preferably in the range of 4 μm to 15 μm. This is because if the wiring thickness is too small, it may not be possible to achieve a sufficiently low impedance, and if the wiring thickness is too large, the suspension substrate may become too rigid.

The line width of the wiring is preferably in the range of 10 μm to 100 μm, for example. If the wiring line width is too small, the desired conductivity may not be obtained. If the wiring line width is too large, the suspension substrate may not be sufficiently dense. Because.
In the present invention, the wiring only needs to have a portion having a width larger than the width of the bottom surface in the thickness direction, and the width dimension of the bottom surface is not particularly limited as long as this condition is satisfied.
However, in order to stably form the wiring on the base insulating layer, the width of the bottom surface is 10% to 40% with respect to the width of the portion having the largest width between the top surface and the bottom surface of the wiring. Preferably, the width is as small as about%.
For example, when the width of the portion having the largest width between the upper surface and the bottom surface of the wiring is 20 μm, the width of the bottom surface is preferably in the range of 12 μm to 18 μm.

Further, the distance between the wirings on the same plane is preferably in the range of 10 μm to 30 μm, for example. If this distance is too small, it is not preferable because it requires high processing accuracy and increases costs. On the other hand, if this distance is too large, the suspension substrate may not be sufficiently dense. Because there is sex.
In the present invention, the wiring only has to have a portion having a width larger than the width of the bottom surface in the thickness direction, and the distance between the bottom surfaces of the wiring is not particularly limited as long as this condition is satisfied.
However, as described above, in order to stably form the wiring on the base insulating layer, the width of the bottom surface is larger than the width of the portion having the largest width between the top surface and the bottom surface of the wiring. The width is preferably about 10% to 40% smaller.
Therefore, for example, when the width of the portion having the largest width between the upper surface and the bottom surface of the wiring is 20 μm and the distance between the wirings in that portion is 20 μm, the distance between the bottom surfaces is 22 μm to 28 μm. It is preferable that it is the range of these.

[Cover insulation layer]
In order to prevent deterioration due to corrosion or the like, each wiring according to the present invention is preferably covered with a cover insulating layer. Moreover, the capacity | capacitance of the capacitive coupling between each wiring can also be enlarged by filling the clearance gap between each wiring with a cover insulating layer.
Examples of the material for the insulating cover layer include polyimide. Further, the material of the cover insulating layer may be a photosensitive material or a non-photosensitive material.
The thickness of the cover insulating layer is, for example, in the range of 4 μm to 30 μm on each wiring constituting the second wiring group.

[Method of manufacturing suspension substrate]
Next, the manufacturing method of the suspension substrate of the present invention will be described. In order to avoid complication, here, the embodiment shown in FIG. 5B will be described among various embodiments. In addition, the manufacturing method of the suspension substrate of the present invention is not particularly limited as long as it is a method capable of obtaining the suspension substrate having the above-described configuration.

7 and 8 are schematic process diagrams showing an example of a method for manufacturing a suspension substrate according to the present invention in the form shown in FIG. 5B.
In order to manufacture the suspension substrate 30 of the present embodiment, first, the base insulating layer 12 is formed on the metal supporting substrate material 31A (FIG. 7A), and then the insulating base layer is formed by sputtering. A thin film conductive material layer 33 is formed on 12 (FIG. 7B).
Next, a resist layer 37A is formed on the thin-film conductor material layer 33 (FIG. 7C), and a resist pattern 37 having openings at wiring portions is formed by using a photoengraving technique (FIG. 7D). )).

Here, in the present invention, the width of the bottom surface of the opening of the resist pattern 37 is made smaller than the width of the other part of the opening of the resist pattern 37. For example, as shown in FIG. 7D, the width (WR1) of the bottom surface of the opening of the resist pattern 37 is made smaller than the width (WR2) of the top surface of the opening of the resist pattern 37.
The opening having the shape as described above can be formed by adjusting the resolution and sensitivity of the resist and controlling the exposure amount during photoengraving. Further, in the resist pattern after development, a residue (bottoming) may be formed from the side walls on both sides of the bottom surface of the opening so that the width of the bottom surface of the opening is smaller than the width of the other part. The opening having the above shape may be formed by intentionally using this residue (bottoming).

Next, wirings 34a, 34b, 34c, and 34d are formed in the openings of the resist pattern 37 by electrolytic plating using the thin film conductor material layer 33 as a seed layer (FIG. 7E), and then the resist pattern 37 is formed. Stripping and removing (FIG. 8 (f)), and etching and removing the exposed thin film conductor material layer 33 other than the portions covered with the wirings 34a, 34b, 34c, and 34d (portions that become the thin film conductors 33a, 33b, 33c, and 33d) (FIG. 8 (g)).
Then, the wiring 34a, 34b, 34c, to form the insulating cover layer 15 to cover the 34d (FIG. 8 (h)), Finally, the metal supporting board having an opening 36 by etching the metal supporting board member 31A 31 is formed to give a suspension substrate 30 according to this embodiment (FIG. 8 (i)).

  Although not shown in order to avoid complication, in the present invention, for example, the connection vias 43a, 43b, 43c, and 43d shown in FIG. 6 are formed in the base insulating layer 12, and the connection lines 44a and 44a are formed. The connection line 44 b can be formed in the opening 36 of the metal support substrate 31.

[suspension]
Next, the suspension according to the present invention will be described. The suspension according to the present invention includes the above-described suspension substrate according to the present invention and a load beam.

  FIG. 9 is a schematic plan view showing an example of a suspension according to the present invention. A suspension 50 shown in FIG. 9 includes the suspension substrate 1 described above, a load beam 51 provided on the back surface side (metal support substrate side) of the suspension substrate 1, and a base plate (not shown). is there. The load beam and the base plate can be the same as the load beam and base plate used for a general suspension.

  In the present invention, by using the above-described suspension substrate according to the present invention, it is possible to obtain a highly reliable suspension that has low impedance and suppresses occurrence of a short circuit.

[Suspension with head]
Next, the suspension with a head according to the present invention will be described. A suspension with a head according to the present invention includes the suspension according to the present invention described above and a magnetic head slider mounted on the suspension.

  FIG. 10 is a schematic plan view showing an example of a suspension with a head according to the present invention. A suspension 60 with a head shown in FIG. 10 has the above-described suspension 50 and a magnetic head slider 61 mounted on the tongue 2 of the suspension 50.

  Since the suspension 50 is the same as described above, the description thereof is omitted here. The magnetic head slider 61 can be the same as the magnetic head slider used in a general suspension with a head.

  According to the present invention, by using the suspension substrate according to the present invention described above, it is possible to obtain a highly reliable suspension with a head that has a low impedance and suppresses occurrence of a short circuit.

[Hard disk drive]
Next, the hard disk drive according to the present invention will be described. A hard disk drive according to the present invention includes the suspension with a head according to the present invention described above.

FIG. 11 is a schematic perspective view showing an example of a hard disk drive according to the present invention.
A hard disk drive 70 shown in FIG. 11 has a case 71, a disk 72 that is rotatably attached to the case 71 and stores data, a spindle motor 73 that rotates the disk 72, and a desired flying on the disk 72. It has a suspension 60 with a head that is provided so as to be close to each other while maintaining a height and that includes a slider for writing and reading data to and from the disk 72. Of these, the suspension 60 with a head is movably attached to the case 71, and a voice coil motor 74 that moves the slider of the suspension 60 with a head along the disk 72 is attached to the case 71. The head suspension 60 is attached to the voice coil motor 74 via an arm 75.

  Note that the suspension with a head is the same as that described above, so description thereof is omitted here. As other members, the same members as those used in a general hard disk drive can be used.

  According to the present invention, by using the above-described suspension with a head, it is possible to obtain a hard disk drive with higher functionality and higher reliability.

  The suspension substrate, suspension, suspension with head, and hard disk drive according to the present invention have been described above, but the present invention is not limited to the above-described embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1, 10, 20, 30 ... Suspension board 2 ... Tongue part 3 ... Connection terminal part 4, 5 ... Wiring group 11, 21, 31 ... Metal support board 12 ... Base Insulating layer 13a, 13b ... Thin film conductor 14a, 14b ... Wiring 15 ... Cover insulating layer 26, 36 ... Opening 31A ... Metal support substrate material 33 ... Thin film conductor material layer 33a, 33b, 33c, 33d ... Thin film conductors 34a, 34b, 34c, 34d ... Wiring 37A ... Resist layer 37 ... Resist pattern 40 ... Interleaved wiring 41a, 41b, 41c, 41d ... Connection Terminal 42a, 42b ... Branch point 43a, 43b, 43c, 43d ... Connection via 44a, 44b ... Connection line 50 ... Suspension 51 ... Load beam 60. -Suspension with head 61-Magnetic head slider 70-Hard disk drive 71-Case 72-Disk 73-Spindle motor 74-Voice coil motor 75-Arm 100, 200 Suspension substrate 111, 211 ... Metal support substrate 112, 212 ... Base insulating layer 114 ... Wiring material layer 114a, 114b, 214a, 214b ... Wiring 115 ... Cover insulating layer 117, 217 ... Resist patterns

Claims (6)

A suspension substrate in which a plurality of wirings are formed on a base insulating layer formed on a metal support substrate,
A cover insulating layer is formed on the base insulating layer,
The wiring includes a portion having a width larger than the width of the bottom surface in the thickness direction,
A plurality of first signal wirings in which the plurality of wirings are electrically connected to each other; and a plurality of second signal wirings that are electrically independent from each other and electrically connected to each other. It has a configuration that is arranged alternately in parallel on a plane,
The width of the bottom surface, the width of the portion with the largest width between the bottom surface from the top surface of the wiring, Ri 10% to 40% less width der,
A portion having the largest width between the top surface and the bottom surface of the wiring is present in the body portion of the wiring, and the wiring width between the bottom surface of the wiring and the portion having the largest width of the wiring is gradually increased. A suspension substrate having a configuration in which the wiring width between the portion having the largest width of the wiring and the upper surface of the wiring is gradually reduced . The suspension substrate according to claim 1 , wherein the insulating cover layer is formed on the wiring.   The metal support substrate has a width that overlaps with a region where the first signal wiring and the second signal wiring are arranged, and is wider than a width of a region where the first signal wiring and the second signal wiring are arranged. The suspension substrate according to claim 1, wherein an opening having a large opening width is formed.   A suspension comprising the suspension substrate according to any one of claims 1 to 3 and a load beam.   A suspension with a head comprising the suspension according to claim 4 and a magnetic head slider mounted on the suspension.   A hard disk drive comprising the suspension with a head according to claim 5.

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