Disk drive flexure

A first conductor member includes an amplifier-side first conductor, a head-side first conductor, and first and second interleaved conductors. A second conductor member includes an amplifier-side second conductor, a head-side second conductor, and third and fourth interleave conductors. The second interleaved conductor is connected to the amplifier-side first conductor through a first jumper conductor. The fourth interleave conductor is connected to the head-side second conductor through a second jumper conductor. The jumper conductors are formed by partially etching a metal base. The jumper conductors are individually inclined at angles of 45° or less to an axis which extends in a wiring direction of each of the interleaved conductors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2009-118631, filed May 15, 2009, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a flexure used in a disk drive for an information processing apparatus, such as a personal computer.

2. Description of the Related Art

A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The hard disk drive comprises a magnetic disk rotatable about a spindle, carriage turnable about a pivot, etc. A disk drive suspension is disposed on an arm of the carriage.

The disk drive suspension comprises a baseplate and load beam. A flexure is located on the load beam. A slider is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for accessing data, that is, for reading or writing data. The suspension, flexure, etc., constitute a head gimbal assembly.

The flexure is any of various available types used depending on the required specifications. A flexure with conductors is a known example. The flexure with conductors comprises a metal base formed of a thin stainless-steel plate, resin layer formed of an electrically insulating resin, such as polyimide, a plurality of conductors of copper, etc. The resin layer is formed on the metal base. The conductors are formed on the resin layer. One end of each conductor is connected to an amplifier or the like of the disk drive. The other end of each conductor is connected to an element (e.g., MR element) of the slider.

The impedance of a conductive circuit portion of the flexure is expected to be reduced in order to match the amplifier and the element of the slider and reduce energy consumption. The inductance is also expected to be reduced. For higher data transfer, moreover, such a property (low-attenuation property) is required that attenuation is low even in a high-frequency band.

A flexure with conductors comprising multi-trace transmission lines can effectively meet these requirements. A circuit provided with the multi-trace transmission lines is also called an interleave circuit. A flexure with an interleave circuit is disclosed in U.S. Pat. No. 5,717,547. The flexure of this type is suitable for high-speed data transfer because of its low attenuation in the high-frequency.

FIG. 16shows an example of a conventional interleave circuit. This interleave circuit comprises first to fourth interleaved conductors201to204. The first and second interleaved conductors201and202diverge from a first conductor member211. The third and fourth interleaved conductors203and204diverge from a second conductor member212.

Thus, the second and fourth interleaved conductors202and204three-dimensionally cross at an intersection220. Further, the second and third interleaved conductors202and203three-dimensionally cross at an intersection221. Connecting wires230and231with electrically insulating coatings are used to prevent short-circuiting of the intersections220and221.

If the connecting wires230and231are used for the intersections220and221, as in the prior art example shown inFIG. 16, they inevitably project vertically relative to the interleave circuit, so that the thickness of the interleave circuit cannot be reduced favorably. Since the connecting wires230and231are required in addition to the interleaved conductors201to204, moreover, there is also a problem of an increase in the number of components.

The inventor hereof carried out a test in which high-frequency data was transferred to the interleave circuit shown inFIG. 16. In this test, the respective phases of the waveforms of currents that flow through respective midpoints m1and m2of the interleaved conductors201and202were measured. Consequently, it was found that a substantial phase difference was produced between current waveforms W1and W2, as shown inFIG. 17, and variation in properties was caused by electrical interaction or the like. It was also found that, depending on the mounted state of the connecting wires230and231, high-frequency attenuation, in particular, may be so high that high-speed data transfer is hindered.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a disk drive flexure having excellent electrical properties, such as low high-frequency attenuation, and configured so that an interleave circuit can be prevented from becoming thick.

The present invention is a disk drive flexure, which comprises a metal base formed of a metal plate, an electrically insulating resin layer formed on the metal base and comprising a first surface in contact with the metal base and a second surface located opposite from the metal base, a first conductor member disposed on the second surface of the resin layer, and a second conductor member disposed parallel to the first conductor member on the second surface of the resin layer.

The first conductor member comprises an amplifier-side first conductor connected to an amplifier, a head-side first conductor connected to a magnetic head, a first interleaved conductor formed between the amplifier-side first conductor and the head-side first conductor, connecting with the amplifier-side first conductor through a first conductor branch section, and connecting with the head-side first conductor through a first conductor joint section, and a second interleaved conductor extending parallel to the first interleaved conductor and connecting with the head-side first conductor through the first conductor joint section.

The second conductor member comprises an amplifier-side second conductor connected to the amplifier, a head-side second conductor connected to the magnetic head, a third interleaved conductor formed between the amplifier-side second conductor and the head-side second conductor, connecting with the amplifier-side second conductor through a second conductor branch section, and connecting with the head-side second conductor through a second conductor joint section, and a fourth interleaved conductor located between and parallel to the first interleaved conductor and the second interleaved conductor and connecting with the amplifier-side second conductor through the second conductor branch section.

The flexure of the invention further comprises a first jumper conductor formed on the first surface of the resin layer so as to be flush with the metal base, electrically isolated from the metal base, connecting with the first conductor branch section through a first terminal which penetrates the resin layer relative to the thickness thereof, and connecting with the second interleaved conductor through a second terminal which penetrates the resin layer relative to the thickness thereof, and a second jumper conductor formed on the first surface of the resin layer so as to be flush with the metal base, electrically isolated from the metal base, connecting with the second conductor joint section through a third terminal which penetrates the resin layer relative to the thickness thereof, and connecting with the fourth interleaved conductor through a fourth terminal which penetrates the resin layer relative to the thickness thereof. The first jumper conductor and the second jumper conductor are individually angled less than 45° to an axis which extends in a wiring direction of each of the interleaved conductors.

According to this arrangement, the first and second jumper conductors that are flush with the metal base are angled at 45° or less to the axis which extends in the wiring direction of each interleaved conductor. Thus, the high-frequency attenuation can be reduced, and an interleave circuit suitable for high-speed data transfer can be obtained.

Further, the amplifier-side first conductor and the second interleaved conductor conduct to each other through the insular first jumper conductor that is flush with the metal base. Furthermore, the head-side second conductor and the fourth interleaved conductor conduct to each other through the insular second jumper conductor that is flush with the metal base. Thus, the jumper conductors never project outwardly relative to the thickness of the interleave circuit. If the jumper conductors are formed by partially etching the metal base, the number of components for the jumper conductors cannot be increased, and the respective surfaces of the jumper conductors can be made flush with that of the metal base.

Preferably, in the present invention, each of the first and second jumper conductors is an insular portion formed by partially etching the metal base. Preferably, moreover, the respective angles of the first and second jumper conductors are equal.

In the present invention, the flexure may further comprise a first bent portion formed between the first conductor branch section and the first interleaved conductor and bent opposite from the first jumper conductor with respect to the axis and a second bent portion formed between the second conductor joint section and the third interleaved conductor and bent opposite from the second jumper conductor with respect to the axis.

Further, an interleaved branch section formed on one end portion of the interleave circuit and an interleaved joint section formed on the other end portion of the interleave circuit may be point-symmetrical with respect to a longitudinal midpoint of the interleave circuit.

DETAILED DESCRIPTION OF THE INVENTION

A hard disk drive (hereinafter referred to as a “disk drive”)1shown inFIG. 1comprises a case2, magnetic disks4, carriage6, and positioning motor7. The magnetic disks4are rotatable about a spindle3. The carriage6is turnable about a pivot5. The positioning motor7turns the carriage6. The case2is covered by a lid (not shown).

FIG. 2is a sectional view typically showing a part of the disk drive1. As shown inFIG. 2, the carriage6comprises a plurality of (e.g., three) actuator arms8. Suspensions10are mounted individually on the respective distal end portions of the actuator arms8. A slider11, which constitutes a magnetic head, is disposed on the distal end of each of the suspensions10.

If the magnetic disks4rotate at high speed about the spindle3, an air bearing is formed between each disk4and slider11. If the carriage6is moved by the positioning motor7, each slider11moves to a desired track of the disk4. The slider11comprises elements, such as MR elements capable of performing conversion between electrical and magnetic signals. By means of these elements, data can be accessed, that is, written to or read from the recording surface of the disk4.

FIG. 3shows an example of a head gimbal assembly comprising the suspension10. The suspension10comprises a baseplate20, load beam21, and hinge member22formed of a thin spring plate. A boss portion20aof the baseplate20is fixed to the actuator arm8.

The suspension10is provided with a flexure30with conductors. The flexure30with conductors will hereinafter be referred to simply as the flexure30. The flexure30is located along the load beam21. Overlapping portions30aof the flexure30and load beam21are fixed to each other by fixing means, such as laser welding. A tongue31, which functions as a gimbal portion, is formed near the distal end of the flexure30. The slider11is mounted on the tongue31. A rear portion (tail portion)30bof the flexure30extends toward an amplifier35, which is located behind the baseplate20.

The flexure30comprises a conductive circuit portion40extending longitudinally relative to it (or in the direction indicated by arrow L inFIG. 3). One end of the circuit portion40is connected electrically to the amplifier35(FIG. 3) of the disk drive1through a circuit board or junction circuit (not shown). The other end of the circuit portion40is connected electrically to an element of the slider11that functions as the magnetic head.

An interleave circuit41is formed on a longitudinal part of the conductive circuit portion40.

FIG. 4shows an interleaved branch section42and interleaved joint section43. The interleaved branch section42is formed on one end portion of the interleave circuit41. The interleaved joint section43is formed on the other end portion of the interleave circuit41. The interleaved branch and joint sections42and43will be described in detail later.

FIG. 5is a sectional view showing a part of the conductive circuit portion40of the flexure30. The conductive circuit portion40comprises a metal base50formed of a metal plate, electrically insulating resin layer51, first and second conductor members55and56for writing, cover layer57, etc. The resin layer51is formed on the metal base50. The cover layer57is formed of an electrically insulating resin, such as polyimide, and covers the conductor members55and56. Arrow Z inFIG. 5indicates the thickness direction of the metal base50, resin layer51, and conductor members55and56. A part of the cover layer57is omitted from the flexure30shown inFIG. 3.

The metal base50is formed of a metal plate, such as a stainless-steel plate. The metal base50is thinner than the load beam21and is, for example, 15 to 20 μm thick. The load beam21is, for example, 30 to 62 μm thick.

The resin layer51has a first surface51ain contact with the metal base50and a second surface51blocated opposite from the metal base50. The first and second conductor members55and56are formed parallel to each other on the second surface51bof the resin layer51. An example of the thickness of the resin layer51is 10 μm, while that of the cover layer57is about 3 μm.

The first and second conductor members55and56are formed of a highly electrically conductive metal, such as deposited copper. The conductor members55and56are formed individually into predetermined patterns by etching along the second surface51bof the resin layer51. Alternatively, the conductor members55and56may be formed into the predetermined patterns by plating without involving etching. The first and second conductor members55and56are continuous longitudinally relative to the flexure30. An example of the thickness of each of the conductor members55and56is 10 μm. The flexure30also comprises a pair of reading conductors (not shown).

The interleave circuit41is formed on a longitudinal part of the conductive circuit portion40.FIG. 4shows the interleaved branch section42and interleaved joint section43. The interleaved branch section42is formed on the one end portion of the interleave circuit41. The interleaved joint section43is formed on the other end portion of the interleave circuit41. The interleaved branch and joint sections42and43are arranged substantially diametrically symmetrical with respect to a longitudinal midpoint C (FIG. 4) of the interleave circuit41.

The first conductor member55shown inFIG. 4comprises an amplifier-side first conductor55a, head-side first conductor55b, first interleaved conductor61, and second interleaved conductor62. The amplifier-side first conductor55ais connected to the amplifier35(FIG. 3). The head-side first conductor55bis connected to the element of the magnetic head (slider11).

The second conductor member56comprises an amplifier-side second conductor56aconnected to the amplifier35, head-side second conductor56bconnected to the element of the magnetic head (slider11), third interleaved conductor63, and fourth interleaved conductor64. The interleaved conductors61to64are arranged parallel to one another. The interleave circuit41has an axis X extending longitudinally relative to the interleaved conductors61to64(or in a reference wiring direction). The interleaved conductors61to64extend longitudinally relative to the flexure30along the axis X.

The first interleaved conductor61is formed between the amplifier-side first conductor55aand head-side first conductor55b. The first interleaved conductor61connects with the amplifier-side first conductor55athrough a first conductor branch section71. Further, the first and second interleaved conductors61and62connect with the head-side first conductor55bthrough a first conductor joint section72.

The third interleaved conductor63is formed between the amplifier-side second conductor56aand head-side second conductor56b. The third interleaved conductor63connects with the amplifier-side second conductor56athrough a second conductor branch section75. Further, the third interleaved conductor63connects with the head-side second conductor56bthrough a second conductor joint section76. The fourth interleaved conductor64connects with the amplifier-side second conductor56athrough the second conductor branch section75.

The fourth interleaved conductor64is located between and parallel to the first and second interleaved conductors61and62. The second interleaved conductor62is located between and parallel to the third and fourth interleaved conductors63and64.

FIG. 6is a sectional view showing the interleaved branch section42. In the example shown inFIG. 6, the load beam21does not exist relative to the thickness of the flexure30. Depending on the position of the interleave circuit41, however, the load beam21may exist relative to the thickness of the flexure30.

The interleaved branch section42comprises first and second terminals81and82and first jumper conductor91formed of an electrically conductive material. The first and second terminals81and82individually penetrate the resin layer51relative to its thickness. The terminals81and82are formed simultaneously with the conductor members55and56that are formed by plating. Specifically, the terminals81and82are formed of the same material as the conductor members55and56. Alternatively, however, the terminals81and82may be formed by depositing a material different from that of the conductor members55and56.

The first jumper conductor91is formed on the first surface51aof the resin layer51so as to be flush with the metal base50. The first jumper conductor91is formed of a metallic material (stainless-steel plate) shared by the metal base50. This conductor91is insular and is electrically insulated from the metal base50. The first jumper conductor91electrically conducts to the first conductor branch section71through the first terminal81. Further, the conductor91electrically conducts to the second interleaved conductor62through the second terminal82.

FIG. 7is a sectional view showing the interleaved joint section43. In the example shown inFIG. 7, the load beam21exists relative to the thickness of the flexure30. Depending on the position of the interleave circuit41, however, the load beam21may not exist relative to the thickness of the flexure30. The interleaved joint section43is formed at that part30aof the overall longitudinal length of the flexure30which overlaps of the load beam21. The interleaved joint section43comprises third and fourth terminals83and84and second jumper conductor92formed of an electrically conductive material.

The third and fourth terminals83and84individually penetrate the resin layer51relative to its thickness. The terminals83and84are formed of the same material as the conductor members55and56that are formed by plating, for example. Alternatively, however, the terminals83and84may be formed by depositing a material different from that of the conductor members55and56.

The second jumper conductor92, like the first jumper conductor91, is formed on the first surface51aof the resin layer51so as to be flush with the metal base50. The second jumper conductor92is formed of a metallic material (stainless-steel plate) shared by the metal base50. This conductor92is insular and is electrically insulated from the metal base50. The second jumper conductor92electrically conducts to the second conductor joint section76through the third terminal83. Further, the conductor92electrically conducts to the fourth interleaved conductor64through the fourth terminal84.

As shown inFIG. 7, the interleaved joint section43is formed at that part30aof the flexure30which overlaps of the load beam21. Therefore, the load beam21is formed with a depression100in a position opposite to the second jumper conductor92. The depression100serves to secure an electrically insulating space G between the second jumper conductor92and load beam21. The depression100is formed by, for example, half-etching a part of the load beam21. Instead of forming the depression100, an opening (through-hole) may be formed penetrating the load beam21relative to the thickness.

The first and second jumper conductors91and92are individually outlined by partially etching the metal base50. Specifically, the respective contours of the conductors91and92are defined by continuous annular slits95and96, as viewed vertically relative to the metal base50. Thus, the insular jumper conductors91and92that are electrically independent of the metal base50are formed by partially etching the stainless-steel plate as the material of the metal base50. In this case, each of the jumper conductors91and92is as thick as the metal base50. Accordingly, the respective surfaces of the conductors91and92are flush with that of the metal base50. Thus, the conductors91and92never project outwardly relative to the thickness of metal base50.

As shown inFIG. 4, the first jumper conductor91is angled at θ1of 30° to the axis X of the interleave circuit41. The axis X extends longitudinally relative to the interleave circuit41(or in the reference wiring direction). A first bent portion111is formed between the first interleaved conductor61and first conductor branch section71. The first bent portion111is bent opposite from the first jumper conductor91with respect to the axis X.

The second jumper conductor92is also angled at θ2of 30° to the axis X. A second bent portion112is formed between the third interleaved conductor63and second conductor joint section76. The second bent portion112is bent opposite from the second jumper conductor92with respect to the axis X.

In the interleave circuit41constructed in this manner, the first and second jumper conductors91and92are formed into independent insular shapes by partially etching the metal base50. Thus, the interleave circuit41can be prevented from becoming thick despite the arrangement of the jumper conductors91and92.

FIG. 8is a circuit diagram typically showing the interleave circuit41of the present embodiment. The interleave circuit41comprises respective midpoints M1and M2of the first and second interleaved conductors61and62.FIG. 9shows current waveforms A1and A2measured at the midpoints M1and M2, respectively. The waveforms of the interleave circuit41of the present embodiment, compared to those (FIG. 17) of the conventional interleave circuit, have better electrical properties involving a smaller phase difference.

FIG. 10shows an interleave circuit41according to a second embodiment of the invention. In the case of this embodiment, angles θ1and θ2of first and second jumper conductors91and92are 0°. Since other configurations of the interleave circuit41are the same as those of the first embodiment, common numbers are used to designate common portions of the first and second embodiments, and a description of those portions is omitted.

FIG. 11shows an interleave circuit41according to a third embodiment of the invention. In the case of this embodiment, angles θ1and θ2of first and second jumper conductors91and92are 45°. Since other configurations of the interleave circuit41are the same as those of the first embodiment, common numbers are used to designate common portions of the first and third embodiments, and a description of those portions is omitted.

FIG. 12shows an interleaved branch section42of an interleave circuit41′ according to a first comparative example. An interleaved joint section (not shown) is shaped to be point-symmetrical with the interleaved branch section42. Angles θ1and θ2of jumper conductors91and92of the first comparative example are 60°.

FIG. 13shows an interleaved branch section42of an interleave circuit41′ according to a second comparative example. An interleaved joint section (not shown) is shaped to be point-symmetrical with the interleaved branch section42. Angles θ1and θ2of jumper conductors91and92of the second comparative example are 90°.

FIG. 14shows an interleaved branch section42of an interleave circuit41′ according to a third comparative example. An interleaved joint section (not shown) is shaped to be point-symmetrical with the interleaved branch section42. Angles θ1and θ2of jumper conductors91and92of the third comparative example are 120°.

FIG. 15shows relationships between the angles θ1and θ2of the jumper conductors91and92and the bandwidth that allows transfer with a loss of 3 dB. The higher the bandwidth, the higher the density of possible data transfer is. The bandwidth of the second embodiment (FIG. 10) with the angles θ1and θ2at 0°, out of the embodiments described above, is as high as about 23a GHz, representing an electric property suitable for high-speed data transfer.

Further, a higher bandwidth is obtained in the case of the first embodiment (FIG. 4) with the angles θ1and θ2at 30°. Also, a bandwidth of 23 GHz or more is obtained in the third embodiment (FIG. 11) with the angles θ1and θ2at 45°.

In the first comparative example (FIG. 12) with the angles θ1and θ2at 60°, on the other hand, the bandwidth is much lower than in the first to third embodiments (with θ1and θ2at 0 to 45°). The bandwidth in the second comparative example (FIG. 13) with the angles θ1and θ2at 90° is substantially equal to that in the first comparative example. The bandwidth in the third comparative example (FIG. 14) with the angles θ1and θ2at 120° is further lower than those in the first and second comparative examples.

Thus, it is to be desired that the jumper conductors91and92be bent at their respective angles θ1and θ2of less than 45° to the axis X that extends in the wiring direction of the interleaved conductors61to64. In the interleave circuits41of the first to third embodiments, the jumper conductors91and92are inclined at their respective angles θ1and θ2of less than 45° to the axis X. In addition, the angles θ1and θ2of the first and second jumper conductors91and92are equal. Accordingly, the interleave circuits41of the first to third embodiments are suitable for data transfer in a high-frequency band.

In the first to third embodiments, the first jumper conductor91is formed flush with the metal base50that is located opposite from the interleaved conductors61to64with the resin layer51therebetween. The second jumper conductor92is also formed flush with the metal base50that is located opposite from the interleaved conductors61to64with the resin layer51therebetween. Thus, conductive paths including the jumper conductors91and92are individually cranked so that a phase difference may be produced between a high-frequency current that passes through the jumper conductors91and92and one that does not.

In the first to third embodiments, therefore, the first bent portion111for extending the corresponding conductive path is formed between the first interleaved conductor61and first conductor branch section71. Further, the second bent portion112is formed between the third interleaved conductor63and second conductor joint section76. Thus, the phase difference can be reduced.

According to the interleave circuit41of the present invention, as described above, high-frequency attenuation can be reduced, and the flexure30obtained is suitable for high-speed data transfer. Further, the amplifier-side first conductor55aand second interleaved conductor62electrically conduct to each other through the first jumper conductor91that is flush with the metal base50. Furthermore, the head-side second conductor56band fourth interleaved conductor64electrically conduct to each other through the second jumper conductor92that is flush with the metal base50. Thus, the jumper conductors91and92never project outwardly relative to the thickness of the interleave circuit41. Since the jumper conductors91and92are formed by partially etching the metal base50, moreover, dedicated components for the conductors91and92are unnecessary. In addition, the respective surfaces of the conductors91and92can be made flush with that of the metal base50.

It is to be understood, in carrying out the present invention, that the constituent elements of the invention, including the first and second conductor members, interleaved branch and joint sections, interleaved conductors, etc., as well as the metal base and resin layer that constitute the flexure, may be embodied in various forms without departing from the spirit or scope of the invention.