JP5218022B2 - Suspension board, suspension, suspension with head and hard disk drive - Google Patents

Description

  The present invention relates to a suspension substrate used in a hard disk drive (HDD), and more particularly to a suspension substrate having a pair of stacked wirings and capable of obtaining a predetermined low differential impedance.

  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 addition, a component called a magnetic head suspension that supports the magnetic head used in the HDD also has a signal line such as a copper wiring directly formed on a stainless steel spring from a conventional type in which a signal line such as a gold wire is connected. The so-called wireless suspension is now integrated into a wiring integrated type (flexure). Further, as the information transmission speed increases, it is necessary to design the suspension substrate as a distributed constant circuit.

  Generally, as shown in Patent Document 1, a pair of wirings formed on such a suspension substrate is formed on the same surface of the insulating layer. Usually, a read wiring composed of a pair of wirings and a write wiring composed of a pair of wirings are respectively formed on the same surface of the insulating layer. Further, such a pair of wires transmits an electric signal by differential transmission, and a differential impedance that is a characteristic impedance of a differential transmission line as a distributed constant circuit exists between the pair of wires. The differential impedance is required to be lowered from the viewpoint of impedance matching as the impedance of the magnetic head and the preamplifier is lowered.

  Here, as described above, in the case of a suspension substrate having a pair of wirings on the same surface of the insulating layer, the line width of the wiring is very wide (for example, several hundred μm) in order to reduce the differential impedance. Alternatively, it is necessary to further reduce the thickness of the insulating layer (for example, 5 μm or less). However, widening the line width of the wiring is not preferable from the viewpoint of increasing the density, and reducing the thickness of the insulating layer increases the occurrence of pinholes.

JP 2005-11387 A

  For the above problem, there is an attempt to change the arrangement of a pair of wirings. Conventionally, as described above, a pair of wirings are arranged (planar arrangement) on the same surface of the insulating layer. However, the pair of wirings are arranged vertically (stacked arrangement) via an insulating member. There is an attempt. The laminated arrangement is usually one wiring (lower wiring) formed on the surface of the first insulating layer (insulating layer formed on the metal substrate) and the second insulation formed so as to cover the lower wiring. And an other wiring (upper wiring) formed on the surface of the layer. The pair of wirings arranged in a stacked manner has the advantage that it is not necessary to increase the line width of the wiring and to reduce the thickness of the first insulating layer, as compared with the case of the conventional planar arrangement.

  However, such a stacked arrangement is not generally known, and the fact is that there is no knowledge to reduce the impedance. Further, in a suspension substrate, a metal substrate usually exists in the vicinity of a pair of wirings arranged in a stacked manner, and it is necessary to consider the influence of this metal substrate on differential impedance. For this reason, it is difficult to reduce the differential impedance in a suspension substrate having a pair of stacked wirings.

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a suspension substrate that has a pair of stacked wirings and can obtain a predetermined low differential impedance. .

  In order to achieve the above object, the present invention covers a metal substrate, a first insulating layer formed on the metal substrate, a lower wiring formed on the first insulating layer, and the lower wiring. A second insulating layer formed and an upper wiring formed on the second insulating layer, wherein the metal substrate is disposed so as not to overlap the lower wiring in plan view, and Provided is a suspension substrate characterized in that it is arranged at a distance that does not affect the differential impedance of a differential wiring comprising a lower wiring and the upper wiring.

  According to the present invention, the differential impedance can be easily designed by arranging the metal substrate at a distance that does not affect the differential impedance of the differential wiring. Thereby, a predetermined low differential impedance (for example, 20Ω ± 2Ω) can be obtained.

  In the above invention, the differential impedance of the differential wiring is preferably within a range of 20Ω ± 2Ω. This is because a suspension substrate suitable for matching with a magnetic head or a preamplifier can be obtained.

  In the present invention, the thickness of the second insulating layer existing from the top of the lower wiring to the bottom of the upper wiring is in the range of 5 μm to 15 μm, and the first insulating layer and the second insulating layer are The relative dielectric constant of the constituent material is in the range of 3.0 to 3.3, the thickness of the lower wiring and the upper wiring is in the range of 5 μm to 15 μm, and the lower wiring and the above It is preferable that the width of the upper wiring is the same and is in the range of 50 μm to 190 μm. This is because with such a configuration, a differential impedance within a range of 20Ω ± 2Ω can be realized.

  The present invention also provides a suspension including the above-described suspension substrate.

  According to the present invention, a suspension with higher functionality can be obtained by using the suspension substrate described above.

  According to the present invention, there is provided a suspension with a head including the above-described suspension and a magnetic head slider mounted on the suspension.

  According to the present invention, by using the suspension described above, it is possible to obtain a suspension with a head with higher functionality.

  The present invention also provides a hard disk drive including the suspension with a head described above.

  According to the present invention, a hard disk drive with higher functionality can be obtained by using the suspension with a head described above.

  The present invention has an effect that a predetermined low differential impedance can be obtained in a suspension substrate having a pair of stacked wirings.

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

A. First, the suspension substrate of the present invention will be described. The suspension substrate of the present invention includes a metal substrate, a first insulating layer formed on the metal substrate, a lower wiring formed on the first insulating layer, and a first wiring formed so as to cover the lower wiring. Two insulating layers and an upper wiring formed on the second insulating layer, and the metal substrate is disposed so as not to overlap the lower wiring in a plan view, and the lower wiring and the upper wiring It is characterized by being arranged at a distance that does not affect the differential impedance of the differential wiring composed of the upper wiring.

  According to the present invention, the differential impedance can be easily designed by arranging the metal substrate at a distance that does not affect the differential impedance of the differential wiring. Thereby, a predetermined low differential impedance (for example, 20Ω ± 2Ω) can be obtained. In addition, according to the present invention, since the lower wiring and the upper wiring have a stacked arrangement in which the second wiring is stacked via the second insulating layer, it is necessary to increase the line width of the wiring as compared with the above-described planar arrangement. This has the advantage that it is not necessary to reduce the thickness of one insulating layer. Therefore, the differential impedance can be sufficiently reduced.

  Next, the suspension substrate of the present invention will be described with reference to FIGS. FIG. 1 is a schematic plan view showing an example of the suspension substrate of the present invention. A suspension board 20 shown in FIG. 1 connects a gimbal part 11 formed at one tip part, a relay board connection part 12 formed at the other tip part, and the gimbal part 11 and the relay board connection part 12. Differential wiring 3 (read wiring 3x and write wiring 3y).

  FIG. 2 is a cross-sectional view taken along the line AA of the region R in FIG. In the present invention, the write wiring 3y is described in the same manner as the read wiring 3x. The suspension substrate shown in FIG. 2 covers the metal substrate 1, the first insulating layer 2a formed on the metal substrate 1, the lower wiring 3a formed on the first insulating layer 2a, and the lower wiring 3a. The second insulating layer 2b formed as described above and the upper wiring 3b formed on the second insulating layer 2b are provided. Furthermore, the metal substrate 1 is disposed so as not to overlap the lower wiring 3a when viewed in plan from the direction of the arrow α shown in FIG. Furthermore, the metal substrate 1 is formed so as not to affect the differential impedance of the differential wiring 3 composed of the lower wiring 3a and the upper wiring 3b.

Here, as shown in FIG. 2, the distance between the edges of the metal substrate 1 of the lower wiring 3a in sectional view, and X ₁ and X _2. X ₁ and X ₂ are independent and are not particularly limited as long as they do not affect the differential impedance of the differential wiring. For example, X ₁ and X ₂ are preferably 10 μm or more, preferably 20 μm or more. It is more preferable that On the other hand, the upper limit of X ₁ and X ₂ is not particularly limited as long as a desired spring property can be ensured, and is, for example, about 60 μm. In FIG. 2, the metal substrate 1 exists in the vicinity of both end portions (the right end portion and the left end portion in the figure) of the lower wiring 3a. In the present invention, either one of them is present. The metal substrate 1 may not be present. Further, the suspension substrate of the present invention may have a cover layer 4 formed so as to cover the upper wiring 3b as shown in FIG.

  Hereinafter, the suspension substrate of the present invention will be described separately for the suspension substrate member and the suspension substrate configuration.

1. First, materials for the suspension substrate of the present invention will be described. The suspension substrate of the present invention usually has at least a metal substrate, a first insulating layer, a lower wiring, a second insulating layer, and an upper wiring. Furthermore, as described above, a cover layer covering the upper wiring may be formed.

  The material of the metal substrate is not particularly limited as long as it has desired conductivity and springiness, and examples thereof include stainless steel. The thickness of the metal substrate is, for example, preferably in the range of 10 μm to 30 μm, and more preferably in the range of 15 μm to 25 μm.

  The material for the first insulating layer and the second insulating layer is not particularly limited as long as it has desired insulating properties, and examples thereof include polyimide (PI). The material of the first insulating layer and the second insulating layer may be a photosensitive material or a non-photosensitive material. Furthermore, the materials of the first insulating layer and the second insulating layer may be the same or different from each other. Moreover, it is preferable that the thickness of a 1st insulating layer and a 2nd insulating layer exists in the range of 5 micrometers-30 micrometers, respectively.

  The material of the lower wiring and the upper wiring is not particularly limited as long as it has desired conductivity, and examples thereof include copper (Cu). Note that a material having electrical characteristics similar to that of pure copper may be used as the wiring material. The thickness of the lower wiring and the upper wiring is preferably in the range of 5 μm to 15 μm, respectively. The line widths of the lower wiring and the upper wiring are preferably in the range of 50 μm to 210 μm, respectively. Note that the thickness and line width of the lower wiring and the upper wiring in the case of obtaining a predetermined differential impedance (for example, 20Ω ± 2Ω) will be described in detail in “2. Configuration of suspension substrate” described later. Further, the lower wiring and the upper wiring may have a protective plating layer formed of nickel (Ni) or gold (Au) on the surface thereof.

  In the present invention, as described above, a cover layer covering the upper wiring may be formed. Examples of the material for the cover layer include polyimide (PI). The material of the cover layer may be a photosensitive material or a non-photosensitive material. The thickness of the cover layer is preferably in the range of 3 μm to 30 μm, for example. In the present invention, it is preferable that the cover layer covers the upper wiring with a larger area so as not to hinder the transmission of the intended electric signal. This is because attenuation of electrical signals and deterioration of wiring can be suppressed.

2. Next, the configuration of the suspension substrate of the present invention will be described. As shown in FIG. 2 described above, in the present invention, the metal substrate 1 is disposed so as not to overlap the lower wiring 3a in plan view. Further, the metal substrate 1 is disposed at a distance that does not affect the differential impedance of the differential wiring 3 composed of the lower wiring 3a and the upper wiring 3b. Note that the distance (X ₁ and X ₂ in FIG. ₂ ) between the end of the lower wiring 3a and the end of the metal substrate 1 in the cross-sectional view is as described above.

  In the present invention, it is preferable that the differential impedance value of the differential wiring composed of the lower wiring and the upper wiring is appropriately selected in consideration of matching with the magnetic head and the preamplifier. Since magnetic heads and preamplifiers have recently been reduced in impedance, it is also required to reduce the differential impedance of the suspension substrate.

  In the present invention, the differential impedance of the differential wiring is preferably in the range of, for example, 20Ω ± 2Ω. This is because a suspension substrate suitable for matching with a magnetic head or a preamplifier can be obtained. Furthermore, in the present invention, the thickness of the second insulating layer (inter-wiring insulating layer) existing from the top of the lower wiring to the bottom of the upper wiring is in the range of 5 μm to 15 μm. The relative dielectric constant of the material constituting the insulating layer is in the range of 3.0 to 3.3, the thickness of the lower wiring and the upper wiring is in the range of 5 to 15 μm, and the lower wiring and the upper wiring It is preferable that the width of each wiring is 50 μm to 190 μm. This is because with such a configuration, a differential impedance within a range of 20Ω ± 2Ω can be realized. The value of the differential impedance may be measured by a known technique or may be calculated by a predetermined simulation.

  Here, the “thickness of the inter-wiring insulating layer” specifically corresponds to the distance Y in FIG. Furthermore, in the above case, it is preferable that the widths of the lower wiring and the upper wiring are the same. Similarly, in the above case, the cover layer is preferably formed so as to cover the upper wiring, and the relative dielectric constant of the material constituting the cover layer is in the range of 3.0 to 3.3. preferable. The members of the suspension substrate are as described above. For example, stainless steel can be used as the material of the metal substrate, copper (Cu) can be used as the material of the lower wiring and the upper wiring, and polyimide (as the material of the first insulating layer, the second insulating layer, and the cover layer) PI) can be used.

  In the present invention, the value of the differential impedance can be changed by adjusting the line width of the differential wiring. Usually, when the line width of the differential wiring is increased, the differential impedance is decreased, and when the line width of the differential wiring is decreased, the differential impedance is increased. The value of the differential impedance is preferably selected as appropriate from the viewpoint of matching with a magnetic head or a preamplifier.

  Further, in the present invention, a pair of wirings arranged in a stack (a pair of wirings as shown in FIG. 2 described above) can be used as at least one of a read wiring and a write wiring. Both of the write wirings are preferably a pair of wirings arranged in a stacked manner. This is because it can be a suspension substrate corresponding to high-speed data. Further, if both the read wiring and the write wiring are a pair of wirings arranged in a stacked manner, the balance can be improved and a suspension substrate can be obtained in which distortion is not easily generated.

  The suspension board of the present invention usually has a gimbal part for mounting the magnetic head slider and a relay board connection part, but the structure and position thereof are the same as those in a general suspension board. The description in is omitted. The method for producing a suspension substrate of the present invention is not particularly limited as long as it is a method capable of obtaining a suspension substrate having the above-described configuration. The suspension substrate of the present invention can be obtained by using a general etching method, coating method and plating method.

B. Suspension Next, the suspension of the present invention will be described. The suspension of the present invention includes the above-described suspension substrate.

  FIG. 5 is a schematic plan view showing an example of the suspension of the present invention. A suspension 40 shown in FIG. 5 includes the above-described suspension substrate 20 and a load beam 30 provided on the surface of the suspension substrate 20 opposite to the surface on which the magnetic head slider mounting region 13 is formed. Is.

  According to the present invention, a suspension with higher functionality can be obtained by using the suspension substrate described above.

  The suspension of the present invention has at least a suspension substrate, and usually further has a load beam. The suspension substrate is the same as the content described in “A. Suspension substrate”, and therefore, the description thereof is omitted here. The load beam can be the same as the load beam used for a general suspension.

C. Next, the suspension with a head according to the present invention will be described. The suspension with a head of the present invention includes the above-described suspension and a magnetic head slider mounted on the suspension.

  FIG. 6 is a schematic plan view showing an example of the suspension with a head of the present invention. A suspension 50 with a head shown in FIG. 6 has the above-described suspension 40 and a magnetic head slider 41 mounted on the magnetic head slider mounting region 13 of the suspension 40.

  According to the present invention, by using the suspension described above, it is possible to obtain a suspension with a head with higher functionality.

  The suspension with a head of the present invention has at least a suspension and a magnetic head slider. The suspension is the same as that described in “B. Suspension” above, and is not described here. Further, the magnetic head slider can be the same as the magnetic head slider used in a general suspension with a head.

D. Next, the hard disk drive of the present invention will be described. The hard disk drive of the present invention includes the above-described suspension with a head.

  FIG. 7 is a schematic plan view showing an example of the hard disk drive of the present invention. The hard disk drive 60 shown in FIG. 7 is connected to the suspension 50 with a head described above, a disk 61 on which the head suspension 50 writes and reads data, a spindle motor 62 that rotates the disk 61, and the suspension 50 with a head. The arm 63, the voice coil motor 64 that moves the magnetic head slider of the suspension 50 with head, and the case 65 that seals the above members are included.

  According to the present invention, a hard disk drive with higher functionality can be obtained by using the suspension with a head described above.

  The hard disk drive of the present invention has at least a suspension with a head, and usually further includes a disk, a spindle motor, an arm, and a voice coil motor. The suspension with a head is the same as the contents described in the above “C. Suspension with a head”, and therefore description thereof is omitted here. As other members, the same members as those used in a general hard disk drive can be used.

  The present invention is not limited to the above 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.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
According to a known method, a suspension substrate having a structure as shown in FIG. 4 was obtained. Here, the distances (X ₁ and X ₂ ) between the end of the lower wiring 3a and the end of the metal substrate 1 were each 40 μm. The first insulating layer 2a, the second insulating layer 2b, and the cover layer 4 are made of polyimide having a relative dielectric constant of 3.3, the lower wiring 3a and the upper wiring 3b are made of copper, and the metal substrate 1 is made of stainless steel. I used steel. The thickness of the first insulating layer 2a was 10 μm, and the thickness of the inter-wiring insulating layer Y was 12.5 μm. Further, the thicknesses of the lower wiring 3a and the upper wiring 3b were both 6 μm. Further, the lower wiring 3a and the upper wiring 3b have the same line width, and the line width was 150 μm. As a result of calculating the differential impedance of the differential wiring of the obtained suspension substrate, the differential impedance was 20 ± 2Ω.

It is a schematic plan view which shows an example of the board | substrate for suspensions of this invention. It is AA sectional drawing of the area | region R in FIG. It is a schematic sectional drawing explaining the board | substrate for suspensions of this invention. It is a schematic sectional drawing explaining the board | substrate for suspensions of this invention. It is a schematic plan view which shows an example of the suspension of this invention. It is a schematic plan view which shows an example of the suspension with a head of this invention. It is a schematic plan view which shows an example of the hard disk drive of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metal substrate 2a ... 1st insulating layer 2b ... 2nd insulating layer 3 ... Differential wiring 3x ... Lead wiring 3y ... Write wiring 3a ... Lower wiring 3b ... Upper wiring 4 ... Cover layer 11 ... Gimbal part 12 ... Relay board connection Part 13: Magnetic head slider mounting area 20 ... Suspension substrate 30 ... Load beam 40 ... Suspension 41 ... Magnetic head slider 50 ... Suspension with head 60 ... Hard disk drive 61 ... Disk 62 ... Spindle motor 63 ... Arm 64 ... Voice coil motor 65 … Case

Claims (6)

A metal substrate, a first insulating layer formed on the metal substrate, a lower wiring formed on the first insulating layer, a second insulating layer formed to cover the lower wiring, and the second An upper wiring formed on the insulating layer, and
The metal substrate is arranged so as not to overlap the lower wiring in plan view, and is arranged at a distance that does not affect the differential impedance of the differential wiring composed of the lower wiring and the upper wiring ,
Both the read wiring consisting of a pair of wirings and the write wiring consisting of a pair of wirings are a pair of wirings arranged in a stack consisting of the lower wiring and the upper wiring,
The upper wiring and the lower wiring are formed so as to overlap in plan view,
The distance that does not affect the differential impedance is such that the distance between the end portion of the lower wiring and the end portion of the metal substrate is 10 μm or more in sectional view.
The suspension substrate, wherein a width of the lower wiring and the upper wiring is in a range of 50 μm to 190 μm .   The suspension substrate according to claim 1, wherein the differential impedance of the differential wiring is within a range of 20Ω ± 2Ω. The thickness of the second insulating layer existing from the top of the lower wiring to the bottom of the upper wiring is in the range of 5 μm to 15 μm,
The relative dielectric constants of the materials constituting the first insulating layer and the second insulating layer are in the range of 3.0 to 3.3, respectively.
The thicknesses of the lower wiring and the upper wiring are in the range of 5 μm to 15 μm,
The suspension substrate according to claim 1 , wherein the lower wiring and the upper wiring have the same width.   A suspension comprising the suspension substrate according to any one of claims 1 to 3.   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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