JP2007287280A - Transmission wiring structure and disk driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the transmission loss of a transmission line, and to suppress noise generated due to a structure therefor. <P>SOLUTION: A suspension is provided with a trace 122 for transmitting the signal of a head slider. The trace 122 is provided with an FPC and connection pads 232a to 232f. The trace 122 is provided with a group of holes 234 to 239 in a metal layer stacked on the connection pads 232a to 232f. In the group of holes 234 to 239, a hole pitch is set equal to or less than a predetermined value because of a relation between the higher harmonic wave of a transmission signal and a frequency. A transmission loss is reduced by the group of holes 234 to 239, and by setting a hole pitch to a predetermined value, the generation of noise by the group of holes 234 to 239 is effectively suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission wiring structure and a disk drive device, and more particularly to formation of a hole in a metal layer of the transmission wiring structure.

  As a disk drive device, there are known devices that use various modes of media such as an optical disk, a magneto-optical disk, or a flexivir magnetic disk. Among them, a hard disk drive (HDD) is a computer storage device. As one of the storage devices indispensable in the present computer system, it is widely used. In addition to computer systems, HDD applications such as moving image recording / playback devices, car navigation systems, and removable memories used in digital cameras are increasingly expanding due to their superior characteristics. .

  The HDD includes a magnetic disk that stores data, a head slider that reads and / or writes data from the magnetic disk, and an actuator that moves the head slider to a desired position on the magnetic disk. The actuator is driven by a voice coil motor, and moves about the rotation axis to move the head slider in the radial direction on the rotating magnetic disk.

  The head slider includes a slider and a head element portion formed on the surface of the slider. The head element section has a recording element that converts an electric signal into a magnetic field according to data stored in the magnetic disk and / or a reproducing element that converts a magnetic field from the magnetic disk into an electric signal. The actuator includes an elastic suspension, and the head slider is fixed to the suspension. The head slider supported by the actuator flies over the rotating magnetic disk with a certain gap.

  The suspension includes a gimbal that holds the head slider on the side facing the magnetic disk, and a load beam that holds the gimbal on the side facing the magnetic disk. A wiring structure (hereinafter referred to as a trace) for transmitting a signal between the preamplifier IC and the element on the head is formed on the actuator. A preamplifier IC is mounted on a flexible printed circuit (FPC) in the vicinity of the rotation axis on the actuator, and the trace is connected to the FPC. The transmission signal of the trace is amplified by the preamplifier IC.

As one structure of the trace, a metal layer continuously formed on the gimbal, a plurality of transmission lines formed on the metal layer, and an insulating layer for insulating each transmission line from the metal layer and other transmission lines What is provided with is known. When the trace has the metal layer, handling at the time of manufacture can be improved. For example, Patent Document 1 discloses that a plurality of holes that overlap with FPC-connected external connection pads are formed in a metal layer of a trace. By forming a hole in a position overlapping the external connection pad of the metal layer, it is said that the parasitic capacitance due to the metal layer can be reduced and the data transfer frequency of the trace can be increased.
JP 2002-251706 A

  However, easy formation of holes in the metal layer of the trace greatly impairs the transmission characteristics of the transmission line. When the transmission line transmits a high-frequency signal, a hole formed in the metal layer appears as a change in impedance with respect to the transmission signal, and multiple reflection of the transmission signal can occur. As a result, noise appears in the transmission signal, and signal quality is deteriorated or accurate signal transmission is impossible. Therefore, when the hole is formed in the metal layer overlapping the connection pad of the trace, a design in consideration of the signal transmission characteristic is required. In particular, the pitch of the holes formed in the metal layer is an important factor affecting the signal transmission characteristics.

  A transmission wiring structure according to one aspect of the present invention includes a metal layer, a transmission line that extends on the metal layer and transmits a signal, the transmission line formed on the metal layer, and other transmission lines. A connection terminal interconnecting the transmission line; and an insulating layer formed between the metal layer and the transmission line and between the metal layer and the connection terminal. The metal layer has a plurality of holes overlapping with the connection terminals. At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is 1/3 of the wavelength of the third harmonic of the transmission signal. 300 or less. Transmission characteristics can be improved by the plurality of holes of the above aspect overlapping the connection terminals.

  The average pitch in the input / output direction of the signal of the transmission line with respect to the connection terminal is preferably 1/300 or less of the wavelength of the third harmonic of the transmission signal. Furthermore, it is preferable that the maximum pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal is 1/300 or less of the wavelength of the third harmonic of the transmission signal. Alternatively, it is preferable that the maximum pitch in all directions of the plurality of holes is 1/300 or less of the wavelength of the third harmonic of the transmission signal. Thereby, it is possible to more reliably prevent adverse effects on the transmission signal due to the plurality of holes.

  In the region of the metal layer that overlaps with the connection terminal, the aperture ratio is preferably 40% or less. Thereby, the mechanical strength of the connection terminal at the time of handling or solder joining can be obtained.

  A transmission wiring structure according to another aspect of the present invention includes: a metal layer; a transmission line that extends on the metal layer and transmits a signal; the transmission line formed on the metal layer; A connection terminal interconnecting the transmission line; and an insulating layer formed between the metal layer and the transmission line and between the metal layer and the connection terminal. The metal layer includes a hole row that overlaps the transmission line and is arranged in a direction in which the transmission line extends, and a plurality of holes that overlap the connection terminal. At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is equal to or less than the main pitch of the hole row. Transmission characteristics can be improved by the plurality of holes of the above aspect overlapping the connection terminals.

  It is preferable that the average pitch in the input / output direction of the signal of the transmission line with respect to the connection terminal is equal to or less than the main pitch of the hole row. Furthermore, it is preferable that a maximum pitch of the plurality of holes in an input / output direction of a signal of the transmission line with respect to the connection terminal is equal to or less than a main pitch of the hole row. Furthermore, it is preferable that the maximum pitch in all directions of the plurality of holes is equal to or less than the main pitch of the hole row. Thereby, it is possible to more reliably prevent adverse effects on the transmission signal due to the plurality of holes.

  A disk drive device according to another aspect of the present invention includes a motor that rotates a disk that records data, a head that accesses the disk, a head that supports the head, and rotates about a rotation axis. An actuator having a wiring structure for moving a head floating above the disk and connecting the head and a wiring board is provided. The wiring structure portion includes a metal layer, a transmission line extending on the metal layer and connected to the head, a connection pad formed continuously with the transmission line and connected to the wiring board, An insulating layer is formed between the metal layer and the transmission line and between the metal layer and the connection pad. The metal layer includes a hole row that overlaps the transmission line and is arranged in a direction in which the transmission line extends, and a plurality of holes that overlap the connection terminal. At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is 1/3 of the wavelength of the third harmonic of the transmission signal. 300 or less.

  ADVANTAGE OF THE INVENTION According to this invention, the transmission characteristic in the wiring structure part which transmits a signal can be improved.

  Hereinafter, embodiments to which the present invention can be applied will be described. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In the drawings, the same elements are denoted by the same reference numerals, and redundant description of each element is omitted as necessary for clarity of explanation. In the following, preferred embodiments of the present invention will be described by taking a hard disk drive (HDD) as an example of a disk drive device as an example.

  The suspension used in the HDD of this embodiment includes a trace that is connected to the head slider and transmits a signal of the head slider. The trace includes a metal layer, a plurality of transmission lines formed on the metal layer, and an insulating layer that insulates each transmission line from the metal layer and other transmission lines. The trace further includes a plurality of connection pads, and each connection pad is connected to an FPC transmission line. The metal layer has a plurality of holes overlapping the connection pads, and the plurality of holes are arranged at a predetermined pitch. By having a plurality of holes with a predetermined pitch where the metal layer overlaps with the connection pads, transmission loss can be reduced without impairing high-frequency transmission characteristics.

  First, the entire configuration of an HDD to which the present invention is applied will be described with reference to FIG. FIG. 1 is a top view schematically showing the overall configuration of the HDD 100 according to the present embodiment. FIG. 1 shows a state of the HDD 100 in which the actuator is in an operating arrangement. A magnetic disk 101, which is an example of a disk for recording data, is a non-volatile recording disk, and records data by magnetizing a magnetic layer. The base 102 is fixed to a cover (not shown) that closes the upper opening of the base 102 via a gasket (not shown) to constitute a disk enclosure as an example of a housing, and accommodates each component of the HDD 100. be able to.

  The clamp 104 fixes the magnetic disk 101 to the spindle motor 103. A spindle motor 103 fixed to the bottom surface of the base 102 rotates the magnetic disk 101 at a predetermined angular velocity (speed). A head slider 105, which is an example of a head, accesses the magnetic disk 101. The head slider 105 has a head element portion having a read and / or write element and a slider to which the head element portion is fixed. The actuator 106 holds and moves the head slider 105. The actuator 106 is rotatably held on a rotary shaft 107 and includes a voice coil motor (VCM) 109 as a drive mechanism for rotating itself. The actuator 106 includes constituent members that are coupled in order of the suspension 110, the arm 111, and the coil support 112 from the tip portion where the head slider 105 is disposed.

  The configuration of the suspension 110 that supports the head slider 105 will be described in detail later. The coil support 112 holds the flat coil 113. The ramp 115 is close to the outer peripheral end of the magnetic disk 101 and has a retreat position for unloading the head slider 105 from the surface of the magnetic disk 101 when the rotation of the magnetic disk 101 stops. The tab 116 is formed at the tip of the suspension 110 and slides on the ramp 115 during loading / unloading. The present invention can also be applied to a CSS (Contact Start Stop) type HDD.

  In order to read / write data from / to the magnetic disk 101, the actuator 106 moves the head slider 105 onto the data area on the surface of the rotating magnetic disk 101. As the actuator 106 rotates, the head slider 105 moves along the radial direction of the recording surface of the magnetic disk 101. The head slider 105 floats over the magnetic disk 101 with a predetermined gap by balancing the force generated on the ABS (Air Bearing Surface) surface of the slider facing the magnetic disk 101 and the pressing force by the suspension 110. .

  A signal of the head slider 105 is transmitted by a trace 122 fixed to the actuator 106. One end of the trace 122 which is an example of the transmission wiring structure is connected to the head slider 105 and the other end is connected to an FPC (Flexible Printed Circuit) 143 on which the preamplifier IC 123 is mounted. The trace 122 transmits a signal between the head slider 105 and the preamplifier IC 123. The trace 122 of this embodiment is formed integrally with the suspension 110, extends from the suspension 110, and extends along the side surface facing the rotation direction of the arm 111 on the opposite side of the magnetic disk 101. The HDD 100 of this embodiment has one characteristic in the structure of the trace 122. This point will be described in detail later.

  The FPC 143 is connected in circuit with a control circuit board (not shown) mounted on the back surface of the base 101 via the connector 147. The FPC 143 transmits a signal between the control circuit and the preamplifier IC 123. The operation control of the HDD 100 and its signal processing are performed by a control circuit on the control circuit board. The FPC 143 transmits power and control signals to the preamplifier IC 123 in addition to read / write signals.

  FIG. 2 schematically shows the configuration of an HSA (Head Stack Assembly) 140 that is an example of a head assembly. The HSA 140 is an assembly including the actuator 106 and the head slider 13. The HSA 140 includes traces 122 a-122 d that extend along the side of the actuator 14. The traces 122a to 122d transmit the head slider 13 signal. The HSA 140 includes an FPC 143, a VCM coil 113 fixed in the coil support 112, a bearing unit hole 145, and HGAs (head gimbal assemblies) 120a to 120d. HGAs 120a to 120d, which are examples of a head assembly, are assemblies of a suspension 110 and a head slider 105 mounted thereon. HGAs 120a-120d are connected to arms 148a-148c of HSA 140, respectively. The arms 148a to 148c are made of a metal such as stainless steel or aluminum.

  FIGS. 3A and 3B are plan views schematically showing the configuration of the head gimbal assembly (HGA) 120 according to the present embodiment. 3A shows a surface facing the recording surface of the magnetic disk 101, and FIG. 3B shows the opposite surface. The suspension 110 according to the present embodiment includes a gimbal 301, a load beam 302, and a mount plate 303. The load beam 302 has a hinge portion 361. The hinge portion 361 has a hole 362 and its rigidity is weakened, and exhibits a spring function that applies a negative pressure against the buoyancy that the head slider 105 receives from the airflow due to the rotation of the magnetic disk 101. Further, the load beam 302 has a rigidity function for supporting the gimbal 301 in a stable posture when the actuator 106 rotates. The base plate 305 has a strength for fixing the load beam 302 to the arm 148.

  The gimbal 301 can be formed of stainless steel, for example, and has a desired elasticity. At the front part of the gimbal 301, a tongue-like gimbal tongue 308 is formed. The head slider 105 is fixed to the gimbal tongue 308 with a low elastic epoxy resin or the like. The gimbal tongue 308 rotates the head slider 105 in the pitch direction or the roll direction around the dimple of the beam plate 304.

  The trace 122 is formed continuously from the gimbal 301 and extends from the end of the gimbal 301. The trace 122 extends from the side of the gimbal 301 opposite to the rotation axis of the magnetic disk 101. The trace 122 extending from the gimbal 301 extends toward the rotation shaft 107 (actuator rear side) along the side of the load beam 302 and the arm (side opposite to the center of the magnetic disk 101). A portion of the trace 122 is welded to the base plate 305 by spot welding.

  In this embodiment, the trace 122 is formed integrally with the gimbal 301. Similar to the wiring structure on the gimbal 301, the trace 122 is formed by a stainless metal layer as a base material, a polyimide insulating layer on the metal layer, a transmission line on the polyimide insulating layer, and a polyimide protective layer (FIG. 5B). )reference). Each layer of the trace 122 is formed continuously with the corresponding layer of the wiring structure on the gimbal 301. The wiring structure on the trace 122 and the gimbal 301 can be formed by a known photolithography etching technique. One end of each transmission line is connected to a circuit on the head slider 105 and performs signal transfer between the preamplifier IC 123 and the head slider 105.

  FIG. 4 schematically shows a structure in which the polyimide protective layer is removed from the trace 122 in FIG. The trace 122 of this example includes six transmission lines, and further has a hole row 255 that overlaps a part of the transmission lines in its metal layer. FIG. 5A schematically shows the structure of a portion surrounded by a circle V in FIG. As shown in FIG. 5A, the trace 122 includes a write line pair 222, a read line pair 223, and a heater line pair 224. The write line pair 222 includes write lines 222a and 222b, the read line pair 223 includes read lines 223a and 223b, and the heater line pair 224 includes heater lines 224a and 224b.

  The write line pair 222 is connected to the write element and transmits a write signal. The lead line pair 223 is connected to the read element and transmits a read signal. The heater line pair 224 transmits a heater signal connected to the heater. A heater line pair 224 extends between the write line pair 222 and the read line pair 223. The head slider 105 of this example includes a heater, and adjusts the amount of protrusion of the head element portion by the heat to control the gap with the magnetic disk 101.

  As described above, the trace 122 has a row of holes 255 that overlap the light line pair 222 in its metal layer. Since the trace 122 has the hole array 255, the transmission loss of the light line pair can be reduced. This will be described in detail later. FIG. 5A illustrates seven holes 255a-255g. Each hole 255a-255g is spaced apart along the light line pair 222, and each hole 255a-255g overlaps the light line pair 222 and is spaced from the other transmission lines.

  FIG. 5B schematically shows a cross-sectional view of the trace 122 taken along the line BB in FIG. FIG. 5C schematically shows a cross-sectional view of the trace 122 taken along the line CC in FIG. 5B and 5C, the trace 122 includes a metal layer 123, a transmission wiring 222-224 formed thereon, and a polyimide insulating layer 124 between the transmission wiring 222-224 and the metal layer 123. And a polyimide insulating protective layer 125 covering the transmission wirings 222-224. As shown in FIG. 5C, the hole 255c overlaps with the light line pair 222 and does not overlap with other transmission lines.

  Returning to FIG. 4, the trace 122 extends from the suspension 110 to the opposite side of the magnetic disk 101, passes through a position facing the hinge portion 361, and further extends along the load beam 302. At the arm side end of the load beam 302, the trace 122 is slightly bent away from the load beam 302, and the tail 221 extends linearly. An end of the tail 221 opposite to the head slider 105 is connected to a tab 231 that is wider than the tail 221. The hole row 255 starts on the gimbal 301 and continues to the vicinity of the tab 231.

  A tab 231 for connecting to the FPC 143 is formed at the rear end portion (rotation shaft side end portion) of the trace 122. The width of the tab 231 is formed larger than the tail 221. The tab 231 is formed with a plurality of connection pads 232 a-232 f for enabling solder connection with the FPC 143. Each connection pad 232 a-232 f is connected to each transmission line 222-224 of the trace 122. The tab 231 is connected to the FPC 143 in the vicinity of the rotation shaft 15 and is connected to the preamplifier IC 123 disposed thereon in a circuit manner.

  6A is an enlarged view of a portion surrounded by a circle VIA in FIG. 3A, and FIG. 6B is an enlarged view of a portion surrounded by a circle VIB in FIG. 3B. As shown in FIG. 6A, the tab 231 has connection pads 232 a-232 f exposed from the protective layer 125. The connection pads 232a to 232f are connected to the FPC 143 by solder. The connection pads 232 a-232 f are separated from each other, and the insulating layer 124 exists between the connection pads 232 a-232 f and the metal layer 123. As shown in FIG. 6B, in the metal layer 123 of the tab 231, a plurality of holes 234-239 are formed in each region overlapping with the connection pads 232a-232f. FIG. 6B shows a part of the hole row 255 overlapping the write line pair.

  FIG. 7A is a perspective view transparently depicting each member of FIG. FIG. 7B schematically shows a cross-sectional structure of a portion indicated by a BB cutting line in FIG. As shown in FIG. 7A, the connection pads 232a and 232b are continuously connected to the write lines 222a and 222b, respectively. The connection pads 232c and 232d are continuously connected to the heater lines 224a and 224b, respectively, and the connection pads 232e and 232f are continuously connected to the lead lines 223a and 223b, respectively.

  The metal layer 123 has hole groups 234-239 each consisting of a plurality of holes, and each hole group 234-239 is formed to overlap with the connection pads 232a-232f, respectively. All or a part of each hole of each hole group 234-239 overlaps with the connection pads 232a-232f. By forming a plurality of holes that overlap with the connection pads 232a to 232f in the metal layer 123, transmission loss in each connection pad 232a to 232f can be reduced. As shown in FIG. 7B, the connection pad 232b is exposed from the insulating protective layer 125, and the insulating layer 124 is formed thereunder. Each hole 235a-235e of the metal layer 123 overlaps the entire area of the connection pad 232b. The insulating layer 124 is exposed from each hole 235a-235e.

  In the example of FIG. 7 (a), each hole group 234-239 is partially overlapped with each corresponding connection pad 232a-232f, and the other partial holes are Only a part overlaps. However, all the holes that overlap the connection pads 232a to 232f may be formed to completely overlap the corresponding connection pads. Moreover, in each hole group 234-239, the internal diameter of the one part hole can differ from the internal diameter of another hole. From the viewpoint of workability, the hole is preferably circular, but is not limited to this shape, and a preferable shape can be selected depending on the design.

  Here, in each hole group 234-239, it is preferable that a plurality of holes are arranged in two directions perpendicular to each other in the plane of the connection pads 232a-232f. In the example of FIG. 7A, a plurality of holes are formed in each of the X and Y axis directions in the figure, specifically, three holes in the X direction and 5 or 6 in the Y axis direction. A hole is formed.

  Here, the influence on the transmission characteristics by the hole group of the metal layer formed so as to overlap the connection pad will be described. When an AC signal flows through the connection pads 232a-232f, an induced current is generated in the metal layer 123. The induced current flowing through the metal layer 123 is induced by transmitting a signal and becomes a signal transmission loss represented by the product of the resistance of the metal layer 123.

  When each hole group 234-239 does not exist, the induced current of the metal layer 123 flows without being interrupted at all. On the other hand, each hole group 234-239 blocks a part of the flow of the induced current of the metal layer 123. Some of the current flows between these holes so as to bypass each hole of the hole group 234-239, but the hole group 234-239 can greatly reduce the value of the current flowing through the metal layer 123. Thereby, transmission loss in signal transmission can be greatly reduced.

  Although the transmission loss can be reduced by the hole group overlapping the connection pad, on the other hand, in the formation of the hole group, it is necessary to consider the influence of multiple reflection due to impedance change. That is, by forming a hole group that overlaps with the connection pad, the impedance with respect to a signal flowing through the connection pad changes between a portion with a hole and a portion without a hole. In order to suppress the occurrence of multiple reflections in signal transmission, the pitch of the holes in the hole group is an important factor.

  Here, the influence of the impedance change due to the presence of the hole group is particularly important in the direction in which the transmission signal current flows. In the connection pad, unlike the transmission line, the signal flows not only in a certain direction but also in all directions. On the other hand, there is a direction in which the transmission signal mainly flows in the connection pad. FIG. 8 schematically shows the connection pad 232b and the structure in the vicinity thereof. As indicated by D in FIG. 8, the input / output direction of the transmission signal with respect to the connection pad 232b is defined from the relationship between the connection pad 232b and the transmission line 222b, but the transmission signal mainly flows in that direction. Therefore, in the formation of holes, the hole pitch in this direction D is particularly important.

  According to the study by the inventors, in the connection pad, the average pitch of the holes in the input / output direction of the transmission signal or the average pitch of the holes in all directions is 1 / th of the wavelength of the third harmonic of the transmission signal. It is preferable that it is 300 or less. By satisfying this condition, an impedance change due to the presence of the hole group does not appear with respect to the transmission signal, and generation of noise that impairs the transmission signal can be prevented.

  In the example of FIG. 8, in the input / output direction D, each hole pitch is the same and is indicated by P1. Therefore, in this direction, both the average pitch and the maximum pitch are P1. Further, the pitch P2 between the holes adjacent in the direction perpendicular to the input / output direction D is larger than P1. The pitch P2 in this direction is all the same in the example of FIG. Therefore, P2 is the maximum pitch in all directions in the hole group 235. The pitch of the holes can be defined as the distance between the centers of adjacent holes. Depending on the design, the pitches P1 and P2 may change depending on the positions of the holes.

  As described above, the hole pitch in the input / output direction of the transmission signal is important for the influence of the impedance change on the transmission signal. Therefore, in particular, the average pitch of the holes in the input / output direction of the transmission signal is preferably 1/300 or less of the wavelength of the third harmonic of the transmission signal. Moreover, it is a more preferable aspect that the average pitch of the holes in the input / output direction of the transmission signal and in all directions is in the above range.

  The impedance change with respect to the transmission signal mainly appears as an average influence of a plurality of holes. In order to suppress the influence more reliably, it is preferable that the maximum pitch of the holes is in the above range. That is, when the maximum pitch of the holes is 1/300 or less of the wavelength of the third harmonic of the transmission signal, it is possible to more reliably prevent noise from being generated in the transmission signal. Again, the direction of the transmission signal is important. Since the maximum pitch in the input / output direction of the transmission signal is 1/300 or less of the wavelength of the third harmonic, the possibility of noise generation can be greatly reduced. In order to achieve a more reliable effect, it is preferable that the maximum pitch in all hole pitches be in the above range.

  In designing the hole pitch, the influence on the transmission characteristics can be effectively suppressed by considering up to the third harmonic. However, in order to perform a more reliable design in terms of noise reduction, it is preferable to consider higher frequency harmonics. According to the study by the inventors, in particular, the influence of the hole pitch on the impedance change can be more reliably suppressed by considering even the fifth harmonic of the transmission signal. Therefore, it is a more preferable design that the value of each hole pitch is set to 1/300 or less of the wavelength of the fifth harmonic of the transmission signal.

  It is necessary to consider a plurality of holes as a region affected by multiple reflection of transmission signals due to impedance changes. Furthermore, the pitch of the plurality of holes needs to be shorter than the wavelength of the third harmonic calculated from the data transfer rate of the HDD 1 or the like. Assuming that the data transfer rate of the HDD 1 is TR, the highest frequency f of the fundamental wave is αTR / 2. Here, α is a coefficient based on data added by data coding, and is typically about 1.1. Further, the wavelength λ of the third harmonic of the actual transmission signal is represented as v / 3f, where v is the propagation speed of the transmission signal.

  According to the study by the inventors, when multiple reflections are taken into account, if the length of at least 10 pitches of holes is 1/30 or less of λ, an effect of preventing noise generation in a transmission signal is expected. And noise generation in the transmission signal can be effectively suppressed. Although the maximum distance between the holes overlapping with the connection pad can be less than 10 pitches as in the above example, the same effect can be obtained when this average pitch satisfies the above-described conditions.

  Here, when the data transfer rate of the HDD 1 is 1 Gbps, the maximum frequency f of the fundamental wave of the transmission signal is 550 MHz (= 1.1 × 1 G / 2). The wavelength λ of the third harmonic is about 97 mm (= 1.6E8 / (3 × 550M)). Therefore, the pitch of the holes is set to about 323 μm (= λ / (30 × 10) = 97 mm / (30 × 10)) or less. Here, when considering up to the fifth harmonic, the pitch of the holes is about 194 μm or less.

  The current induced in the metal layer 123 increases as the frequency of the transmission signal increases. The signal to the heater is close to direct current compared to the read signal and the write signal. The read signal shows a waveform close to a sine wave, whereas the write signal shows a waveform close to a rectangular wave. For this reason, the harmonic component of the write signal is larger than that of the read signal. Therefore, the hole groups 234 and 235 are particularly important in the connection pads 232a and 232b for transmitting the write signal. On the other hand, the effect is small for a line pair such as the heater line pair 224 that hardly changes or whose transmission signal changes at a very low frequency.

  In the above-described example, the hole groups 234-239 are formed corresponding to the connection pads 232a-232f. For example, the hole groups 234 corresponding to only the connection pads 232a, 232b for transmitting a write signal. 235 can also be formed. Alternatively, hole groups 234, 235, 238, 239 corresponding only to the write and read signal connection pads can be formed.

  Thus, the hole group is important in the transmission of the write signal. In the above example, only the hole row 255 overlapping the light line pair 222 is shown as the hole row overlapping the transmission line. The hole row 255 can reduce the transmission loss of the transmission line 222 like the hole group corresponding to the connection pad. In forming the hole row 255, it is necessary to consider the impedance change due to the presence of the hole group, as in the case of the hole group. The hole pitch of the hole row 255 is determined in consideration of the transmission characteristics in the light line pair 222. However, in order not to impair the transmission characteristics of the transmission line defined by the hole row 255, the hole pitch of the hole groups 234 and 235 is preferably equal to or less than the pitch of the hole row 255. It is to be noted that transmission loss can be reduced by forming hole rows in the same manner for the lead line pair 223 as well. In this case, it is preferable to set the hole pitch from the same viewpoint as described above.

  The write signal and the read signal are transmitted by a differential signal transmission method (balanced transmission). For this reason, it is not preferable that there is a difference in transmission characteristics between the connection pads. Therefore, it is preferable that the hole groups 234 and 235 are formed in each of the connection pads 232a and 232b for transmitting the write signal, and that these hole groups 234 and 235 are formed under the same conditions. preferable. The same applies to the connection pads 232e and 232f that transmit the read signal.

  This point can be applied to the hole row 255 as well. That is, it is important that each hole 255a-255g similarly overlaps both lines of the write line pair 222. This is because if the hole overlaps only one of the line pairs, the transmission characteristics between the lines change, a common mode current is generated, and radiation problems may also occur. The heater signal (power) can be transmitted in a balanced or unbalanced manner.

  From the viewpoint of electrical characteristics, it is important that the pitch of the holes in the hole group satisfies the above conditions. On the other hand, the connection pads 232a-232f are connected to the FPC 143 by solder. For this reason, it is also important to design the hole group from the point of mechanical design. In the region overlapping the connection pad, the aperture ratio due to the hole group is preferably 40% or less.

  As a result, mechanical strength at the time of handling and solder joining can be obtained, and electrical contact by solder joining can also be reliably obtained. In particular, when solder is fixed to the connection pads 232a to 232f in advance and is crushed and then connected to the FPC 143, strength in the solder crushing process is important. For this reason, in such an HDD 1, the aperture ratio due to the hole group is preferably 30% or less in the region overlapping the connection pad.

  As mentioned above, although this invention was demonstrated taking preferable embodiment as an example, this invention is not limited to said embodiment. A person skilled in the art can easily change, add, and convert each element of the above-described embodiment within the scope of the present invention. For example, the trace may not include a heater line pair, or may have transmission lines that transmit other signals instead or in addition thereto. The present invention can be applied to both perpendicular magnetic recording and horizontal magnetic recording HDDs, as well as a head having only a read or write element. In addition to apparatuses using other types of recording disks, the present invention can be applied to various forms of transmission wiring structures that transmit high-frequency signals.

In this embodiment, it is a top view which shows typically the whole structure of a hard-disk drive. In this embodiment, it is a top view which shows typically the structure of a head stack assembly. In this embodiment, it is a top view which shows typically the structure of a head gimbal assembly. In this embodiment, it is the top view which has shown typically the structure which removed the polyimide protective layer from the trace in Fig.3 (a). FIG. 5 is a diagram schematically showing a structure of a part of a trace surrounded by a circle V in FIG. 4 in the present embodiment. In this embodiment, it is a figure which shows typically the tab structure of a trace. In this embodiment, it is a figure which shows typically the tab structure of a trace, Comprising: It is the figure which transparently drawn each member of Fig.6 (a). In this embodiment, it is a figure explaining the pitch of the hole in a connection pad, and the input-output direction of a transmission signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hard disk drive, 101 Magnetic disk, 102 Base 103 Spindle motor, 104 Top clamp, 105 Head slider 106 Actuator, 107 Actuator rotating shaft 109 Voice coil motor, 110 Suspension, 111 Arm 112 Coil support, 113 flat coil, 115 lamp, 116 tab 120 head gimbal assembly, 123 preamplifier IC, 122 trace 143 FPC, 147 FPC connector, 221 tail 222 light line pair, 223 lead line pair 224 heater line pair 232a-232f connection pad 234-239 hole group, 255 hole array, 255a-255g hole, 301 gimbal 302 load beam, 303 m Und plate, 308 gimbal tongue 361 hinge part, 362 hinge part hole

Claims (14)

A metal layer;
A transmission line extending over the metal layer and transmitting a signal;
A connection terminal interconnecting the transmission line and the other transmission line formed on the metal layer;
An insulating layer formed between the metal layer and the transmission line and between the metal layer and the connection terminal;
The metal layer has a plurality of holes overlapping with the connection terminals,
At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is 1 / wavelength of the third harmonic of the transmission signal. 300 or less,
Transmission wiring structure. The average pitch in the input / output direction of the signal of the transmission line with respect to the connection terminal is 1/300 or less of the wavelength of the third harmonic of the transmission signal.
The transmission wiring structure according to claim 1. The maximum pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal is 1/300 or less of the wavelength of the third harmonic of the transmission signal.
The transmission wiring structure according to claim 2. The maximum pitch in all directions of the plurality of holes is 1/300 or less of the wavelength of the third harmonic of the transmission signal.
The transmission wiring structure according to claim 1. In the region of the metal layer overlapping the connection terminal, the aperture ratio is 40% or less.
The transmission wiring structure according to claim 1. At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is 1/5 of the wavelength of the fifth harmonic of the transmission signal. 300 or less,
The transmission wiring structure according to claim 1. A metal layer;
A transmission line extending over the metal layer and transmitting a signal;
A connection terminal interconnecting the transmission line and the other transmission line formed on the metal layer;
An insulating layer formed between the metal layer and the transmission line and between the metal layer and the connection terminal;
The metal layer has a plurality of holes that overlap the transmission line and are arranged in a direction in which the transmission line extends, and a plurality of holes that overlap the connection terminal,
At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is equal to or less than the main pitch of the hole row,
Transmission wiring structure. The average pitch in the input / output direction of the signal of the transmission line with respect to the connection terminal is equal to or less than the main pitch of the hole row,
The transmission wiring structure according to claim 7. The maximum pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal is equal to or less than the main pitch of the hole row
The transmission wiring structure according to claim 8. The maximum pitch in all directions of the plurality of holes is equal to or less than the main pitch of the hole row.
The transmission wiring structure according to claim 7. In the region of the metal layer overlapping the connection terminal, the aperture ratio is 40% or less.
The transmission wiring structure according to claim 7. At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is 1/3 of the wavelength of the third harmonic of the transmission signal. 300 or less,
The transmission wiring structure according to claim 1. The average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes are 1/300 or less of the wavelength of the third harmonic of the transmission signal. is there,
The transmission wiring structure according to claim 1. A motor that rotates a disk for recording data;
A head for accessing the disk;
An actuator having a wiring structure for supporting the head and moving the head floating on the disk by rotating about a rotation axis and connecting the head and a wiring board; and
The wiring structure portion includes a metal layer, a transmission line extending on the metal layer and connected to the head, a connection pad formed continuously with the transmission line and connected to the wiring board,
An insulating layer formed between the metal layer and the transmission line and between the metal layer and the connection pad;
The metal layer has a plurality of holes that overlap the transmission line and are arranged in a direction in which the transmission line extends, and a plurality of holes that overlap the connection terminal,
At least one of the average pitch of the plurality of holes in the input / output direction of the signal of the transmission line with respect to the connection terminal and the average pitch in all directions of the plurality of holes is 1 / wavelength of the third harmonic of the transmission signal. 300 or less,
Disk drive device.

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