JP2006277911A - Head stack assembly and its manufacturing method and magnetic disk device having the head stack assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a head stack assembly which can effectively suppress deformation of an arm and to provide a magnetic disk device having the head stack assembly. <P>SOLUTION: The manufacturing method is for the head stack assembly which has a suspension 130 that supports a head, an arm 144 that drives the head and base plates 150 that mount the suspension 130 onto the arm 144. The base plates 150 are fastened, by caulking, to the arm 144 by inserting the base plates 150 having bosses that have openings into the through-hole of the arm 144 and by passing a processing member, whose size is larger than the openings, through the openings of the bosses in one direction within the through-hole. Let the surface, which makes the thickness of the arm 144 one half, be the neutral surface. Then, the caulking position, which is the middle position between a first position located at the uppermost stream side and a second position located at the most downstream side, is set within the range of ±10% of the thickness of the arm 144 from the neutral surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to a head stack assembly for supporting and driving a head and a magnetic disk apparatus having the head stack assembly, and more particularly to a method for connecting a suspension and an arm in a head stack assembly. The present invention is suitable for manufacturing a head stack assembly used in, for example, a hard disk drive (HDD).

  With the recent spread of the Internet and the like, the demand for recording a large amount of information including images and videos has increased. For this reason, the demand for increasing the capacity of magnetic disk devices such as HDDs is increasing. The HDD typically includes a disk to which a magnetic material is attached, and a head stack assembly (HSA) that supports the head and moves to a desired position on the disk. The HSA is a carriage that swings around an axis by a motor (“actuator”, also called “E block” or “actuator (AC) block” because the cross section is substantially E-shaped), and a support portion of the carriage (Hereinafter referred to as “arm”), a magnetic head portion supported by the suspension, and a base plate for attaching the suspension to the arm. The magnetic head unit is composed of a micro head core (hereinafter simply referred to as “head”) for recording and reproducing signals and a slider for supporting the head core.

  The suspension also has a leaf spring function that presses the slider against the disk with a predetermined pressing force. When the disk rotates, an air flow (air bearing) accompanying the rotation is formed between the slider and the disk, and the slider floats from the disk surface. The flying slider is separated from the disk by a certain distance due to the balance between the flying force and the pressing force. In this state, the arm turns to move (seek) the head to a desired position on the disk to read and write information.

  Recent high recording density disks require high precision head positioning accuracy, and it is necessary to manufacture HSA with high precision. For example, if the suspension is warped or twisted due to a manufacturing error, the pressing force acting on the slider, the flying height, the posture, the vibration characteristics and the like are changed from the design values, and the positioning accuracy is lowered.

  In HSA, the suspension and the base plate are laser welded, but the base plate and the arm are crimped. Caulking is a method in which a part of a base plate is crushed against an arm and plastically deformed to join the two. The base plate and the arm that have been crimped can be separated by inserting a sharp member such as a knife between them, and such crimping improves the economics of the magnetic disk drive. This is because if there is a defect in the suspension or the magnetic head, it is sufficient to replace only the base plate side, and there is no need to replace the entire HSA.

However, the force applied to plastically deform the base plate brings about deformation such as warping of the base plate, and reduces the positioning accuracy of the head. Therefore, a method has been proposed in which a thin portion is formed between a portion where the base plate receives the deformation force and a joint portion of the suspension to reduce the deformation of the base plate from affecting the suspension (for example, Patent Document 1). See
JP-A-7-192420

  The inventors of the present invention have found that the deformation of the base plate is a superposition of the deformation of the base plate itself subjected to the plastic deformation force and the deformation of the arm. For this reason, in the method of patent document 1 which tries to prevent only the former, it cannot fully reduce that the deformation | transformation by an arm reaches a baseplate.

  Accordingly, an object of the present invention is to provide a method of manufacturing an HSA that effectively suppresses deformation of the arm, and a magnetic disk device having the HSA.

  A method of manufacturing an HSA as one aspect of the present invention is a method of manufacturing a head stack assembly including a suspension that supports a head, an arm that drives the head, and a base plate that attaches the suspension to the arm. With the base plate having a boss having an opening inserted into the through hole of the arm, the base plate is formed by penetrating the opening of the boss in one direction in the through hole with a processing member larger than the opening. And a step of crimping the arm to the arm, and assuming that the surface that halves the thickness of the arm is a neutral surface, the base plate is positioned along the one direction out of the positions where the base plate contacts the arm after the crimping step. Intermediate position between the first position on the most upstream side and the second position on the most downstream side There crimping position is characterized in that it is in the range from the neutral plane of ± 10% of the thickness of the arm. If the caulking position is within such a range, the moment that the arm receives around the neutral plane by the base plate becomes small, so that deformation of the arm can be prevented. In consideration of manufacturing variations of the base plate, the caulking position is preferably within a range of ± 5% of the thickness of the arm from the neutral surface.

  The HSA according to another aspect of the present invention is a head stack assembly including a suspension that supports a head, an arm that drives the head, and a base plate that attaches the suspension to the arm. The base plate has a boss that is caulked to the arm, and the base plate has a boss that is caulked to the arm. It is characterized by that. If the caulking position is within such a range, the moment that the arm receives around the neutral plane by the base plate becomes small, so that deformation of the arm can be prevented. When the surface that halves the thickness of the arm is a neutral surface, the first position that is the most upstream in the direction in which the caulking fastening working member moves among the positions where the base plate contacts the arm The caulking position, which is an intermediate position between the second position and the most downstream side, may be within a range of ± 10%, preferably ± 5% of the thickness of the arm from the neutral plane. Thereby, there can exist an effect | action similar to the above-mentioned manufacturing method.

  A magnetic disk drive characterized by having the above-described HSA or the HSA manufactured from the above-described method can maintain high positioning accuracy, and constitutes one aspect of the present invention.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, it is possible to provide a method of manufacturing an HSA that effectively suppresses deformation of the arm, and a magnetic disk device having the HSA.

  Hereinafter, an HDD 100 as an embodiment of the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the HDD 100 houses a plurality of magnetic disks 104 serving as record carriers, a spindle motor 106, and an HSA 110 in a housing 102. Here, FIG. 1 is a schematic plan view of the internal structure of the HDD 100.

The casing 102 is made of, for example, an aluminum die-cast base or stainless steel, has a rectangular parallelepiped shape, and is coupled with a cover (not shown) that seals the internal space. The magnetic disk 104 of this embodiment has a high surface recording density, for example, 200 Gb / in ² or more. The magnetic disk 104 is mounted on the spindle of the spindle motor 106 through a hole provided in the center thereof.

  The spindle motor 106 rotates the magnetic disk 104 at a high speed such as 15000 rpm, and has, for example, a brushless DC motor (not shown) and a spindle that is a rotor part thereof. For example, when two magnetic disks 104 are used, a disk, a spacer, a disk, and a clamp are stacked in this order on the spindle and fixed by bolts fastened to the spindle. Unlike the present embodiment, the magnetic disk 104 may be a disk having a hub without having a central hole. In this case, the spindle rotates the disk through the hub.

  The HSA 100 includes a magnetic head unit 120, a suspension 130, a carriage 140, and a base plate 150.

As shown in FIG. 2, the magnetic head unit 120 is joined to an Al ₂ O ₃ —TiC (Altic) slider 121 formed in a substantially rectangular parallelepiped and an air outflow end of the slider 121 for reading and writing. And a head element built-in film 123 made of Al ₂ O ₃ (alumina) in which the head 122 is built. Here, FIG. 2 is an enlarged perspective view of the magnetic head unit 120. The slider 121 and the head element built-in film 123 define a medium facing surface that faces the magnetic disk 104, that is, a flying surface 124. The airflow 125 generated based on the rotation of the magnetic disk 104 is received by the air bearing surface 124.

  On the air bearing surface 124, two rails 126 extending from the air inflow end toward the air outflow end are formed. A so-called ABS (air bearing surface) 127 is defined on the top surface of each rail 126. In the ABS 127, buoyancy is generated according to the action of the airflow 125. The head 122 embedded in the head element built-in film 123 is exposed by the ABS 127. The flying method of the magnetic head unit 120 is not limited to this form, and a known dynamic pressure lubrication method, static pressure lubrication method, piezo control method, and other flying methods can be applied. The starting method may be a contact start / stop method in which the magnetic head unit 120 contacts the disk 104 at the time of stopping, or the magnetic head unit 120 is lifted from the disk 104 at the time of stopping and is magnetically displayed by a ramp outside the disk 104. A dynamic loading method or a ramp loading method in which the head unit 120 is held in non-contact with the disk 104 and dropped from the holding unit onto the disk 104 at the time of activation may be employed.

  The head 122 operates from an induction writing head element (hereinafter referred to as “inductive head element”) that writes binary information on the magnetic disk 104 using a magnetic field generated by a conductive coil pattern (not shown), and the magnetic disk 104. An MR inductive composite head having a magnetoresistive effect (hereinafter referred to as “MR”) head element that reads binary information based on a resistance that changes in accordance with a magnetic field. MR head elements include GMR (current magnetoplane) using CIP (Current in Plane) structure, GMR using Current Perpendicular to Plane (CPP) structure, Giant Magnetoresistive (TMR), and TMR (Tunneling Magnetive MR). (Anisotropic Magnetosensitive) etc. are not ask | required.

  The suspension 130 has a function of supporting the magnetic head unit 120 and applying an elastic force to the magnetic head unit 120 against the magnetic disk 104, and is, for example, a stainless steel Watras suspension. Such a suspension has a flexure (sometimes referred to as a gimbal spring or other name) for cantilevering the magnetic head portion 120 and a load beam (sometimes referred to as a load arm or other name) connected to a base plate. The load beam has a spring portion at the center so as to apply a sufficient pressing force in the Z direction. Therefore, the load beam has a rigid portion at the base end, a spring portion at the center, and a rigid portion at the distal end. Further, the load beam and the flexure are in contact with each other through a projection called a dimple (sometimes referred to as a pivot or other name) so that the ABS 124 always follows the warp and waviness of the disk and is always parallel to the disk surface. The magnetic head unit 120 is designed so that it can be pitched and rolled softly around the dimples. The suspension 130 also supports a wiring part 138 connected to the magnetic head part 120 via a lead wire or the like. The wiring part 138 is shown in FIG. Sense current, write information, and read information are supplied and output between the head 122 and the wiring unit 138 through such lead wires. The wiring part 138 is connected to a relay flexible circuit board (relay FPC) 143 that passes under the arm 144 shown in FIG.

  In the present embodiment, as will be described later, since the amount of warping of the base plate 150 is reduced, the flatness of the suspension 130 and the magnetic head unit 120 is improved. For this reason, it is possible to prevent a crash and a decrease in positioning accuracy due to excessive elastic force or twisting force.

  The carriage 140 has a function of rotating the magnetic head unit 120 in the direction of the arrow shown in FIG. 1, and as shown in FIGS. 1 and 3A to 3B, the carriage 140 and the support are supported. It has a shaft 142, an FPC 143, and an arm 144. 3A is a left side view of the HSA 110, FIG. 3B is a plan view of the HSA 110, and FIG. 3C is a right side view of the HSA 110. Here, the carriage 140 that drives the six magnetic head units 120 that record and reproduce both surfaces of the three disks 104 is shown, but it goes without saying that the number of disks is not limited to three.

  The voice coil motor 141 has a flat coil 141b sandwiched between two yokes 141a. The flat coil 141b is provided to face a magnetic circuit provided on the housing 102 side of the HDD 100 (not shown), and the carriage 140 swings around the support shaft 142 in accordance with the value of the current flowing through the flat coil 141b. . The magnetic circuit has, for example, a permanent magnet fixed to an iron plate fixed in the housing 102 and a movable magnet fixed to the carriage 140. The support shaft 142 is fitted into a cylindrical hollow hole provided in the carriage 140 and is disposed in the housing 102 so as to extend perpendicular to the paper surface of FIG. The FPC 143 supplies a control signal, a signal to be recorded on the disk 104, and power to the wiring unit 138 and receives a signal reproduced from the disk 104.

  The arm 144 is a rigid body made of aluminum provided to be rotatable or swingable around the support shaft 142, and a through-hole 145 described later is provided at the tip thereof. The suspension 130 is attached to the arm 144 through the through hole 145 of the arm 144 and the base plate 150. As shown in FIGS. 3A and 3C, the arm 144 is formed in a comb shape when viewed from the side.

  The base plate 150 has a function of attaching the suspension 130 to the arm 144. As shown in FIGS. 4A to 5B, the base plate 150 includes a flat plate portion 151, a welded portion 152, and a dent (dowel) 154. Have. The welded portion 152 is the tip of a flat plate portion 151 that is laser-welded to the suspension 130. The recess 154 is a portion that is fastened to the arm 144 by caulking. 4A is a schematic plan view of the suspension 130 to which the base plate 150 is joined, and FIG. 4B is a schematic cross-sectional view thereof. FIG. 5A is a schematic plan view of the base plate 150, and FIG. 5B is a schematic cross-sectional view of the base plate 150.

  Hereinafter, the connection between the fourth arm 144 from the top shown in FIG. 3A and the base plate 150 will be described with reference to FIG. The fourth arm 144 from the top shown in FIG. 3A has a single head structure to which the base plate 150 is attached on one side. Here, FIG. 6 is a flowchart for explaining the connection between the arm 144 and the base plate 150.

  First, as shown in FIGS. 5A and 5B, a base plate 150 is created (step 1002). In step 1002, the depression 154 is formed in the flat plate portion 151 of the base plate 150 by press working. As shown in FIG. 7, the recess 154 has a protruding portion 156 and an opening 157 at its tip. The overhanging portion 156 and the vicinity thereof constitute an L-shaped boss 155 that is plastically deformed. Here, FIG. 7 is a schematic enlarged plan view and a sectional view of the base plate 150. The depth of the recess 154 or the position of the boss 155 is set based on the relationship between a caulking position, which will be described later, and the neutral plane IS.

  Next, as shown in FIGS. 4A and 4B, the welded portion 152 of the base plate 150 and the suspension 130 are laser-welded (step 1004). The magnetic head unit 120 is attached to the suspension 130 before or after step 1004.

Next, as shown in FIG. 8, the base plate is arranged on the arm so that the recess 152 of the base plate 150 is inserted into the through hole 145 of the arm 144 (step 1006). Here, FIG. 8 is a diagram illustrating a state in which the base plate 150 is disposed on the arm 144. In this embodiment, as will be described later, the depth of the recess 154 is set so that the caulking position of the base plate 150 substantially coincides with the neutral plane. Next, caulking is performed (step 1008). In the caulking, as shown in FIG. 8, a ball 50 having a diameter slightly larger than the diameter of the opening 157 is passed through the through hole 145 along one direction indicated by an arrow. As a result, the boss 155 of the base plate 150 is crushed and plastically deformed as indicated by the horizontal arrow shown in FIG. 8, thereby joining the base plate 150 and the arm 144 together. In addition, as shown by a one-dot chain line in FIG. 8, a surface that halves the thickness of the arm 144 and is perpendicular to the central axis of the through hole 145 is called a neutral surface IS.

  The inventors of the present invention have examined the reason why the conventional base plate warps downward. The deformation of the base plate is affected not only by the deformation of the base plate itself subjected to the plastic deformation force by the balls 50 but also by the deformation of the arm 144. I found out that

First, if the shape of the conventional base plate is exaggerated and written, the result is as shown in FIG. Here, FIG. 9A is a partially enlarged sectional view showing the arrangement of the conventional base plate 30 and the arm 144 before the caulking is fastened. Position the ball 50 is in contact with the first base plate 30 (power point) _{P 2} is a position where the base plate 30 is in contact with the arm 144 (the fulcrum) above the _{P 1} (i.e., the neutral plane IS than the fulcrum _{P 1} is the power point _{P 2} On the side). This overhang 32 when the power point P ₂ is the ball 50 if the neutral plane IS side than the fulcrum P ₁ passes easily deformed in the direction of the arrow in the counterclockwise than deforms the arm 144 direction. If the deformation force applied by the ball 50 is spent much in the downward deformation of the overhanging portion 32 and the horizontal deformation is reduced, the fastening force or contact force exerted on the arm 144 by the boss 31 is weakened. This is because the arm 144 can be easily separated from the arm 144.

As it is shown in a simplified manner in FIG. 9 (b), the boss 31 the boss 31 receives a force F ₁ vertically downward by the ball 50 is deformed in both downward not only deformed in the horizontal direction. Further, a contact force F ₃ acts from the boss 31 to the arm 144. Here, FIG. 9B is a partially enlarged cross-sectional view showing the force acting on the base plate 30 by the caulking and the magnitude of the contact force from the base plate 30 to the arm 144.

Then, the arm 144 from the neutral plane IS around the contact force F ₃ is deformed to lower as shown in FIG. 9 (c) receiving FIG 9 (b) in the counterclockwise moment. Then, following the arm 144, the base plate 30 is deformed downward. This is the deformation that the base plate 30 is caused by the deformation of the arm 144. The base plate 30, due to the deformation of the protruding portion 32 by the force F ₁ itself also deformed. As a result, the deformation of the base plate 30 is an overlap of the deformation of the base plate 30 and the deformation of the arm 144. Here, FIG. 9C is a partial enlarged cross-sectional view showing the deformation of the base plate 30 and the arm 144 after the caulking.

In order to reduce the deformation of the base plate 30 due to the deformation of the arm 144, the present inventors have studied to configure the arm 144 so that the moment that the arm 144 receives around the neutral plane IS is minimized. That is, in FIG. 8, when the contact force exerted by the boss 155 of the base plate 150 on the arm 144 is F ₁₁ , and the distance between the point (caulking position) P _{11 at} which the contact force F ₁₁ acts and the neutral plane IS is L ₁₁ , In the present embodiment, the moment M ₁ = F ₁₁ × L ₁₁ exerted on the arm 144 around the neutral plane IS by the boss 155 of the base plate 150 is made zero by making L ₁₁ substantially zero. This is because the moment acting on the arm 144 becomes zero and the deformation of the arm 144 is reduced.

However, as shown in FIG. 10, the base plate 150 is actually crimped to the arm 144 by the surface. Here, FIG. 10 is a partially enlarged sectional view of the base arm 150 caulked by the arm 144. The cross section is a cross section including the central axis of the through hole 145 of the arm 144. Of the positions where the base plate 150 is in contact with the arm 144, the position that is an intermediate position (ie, (α + β) / 2) between the position α that is the most upstream side along the caulking direction C and the position β that is the most downstream side is the caulking position. it is a P _11.

FIG. 11 shows the relationship between the caulking position from the neutral plane and the amount of warpage. From the figure, when the caulking position coincides with the neutral plane, the amount of warping of the arm 144 and the base plate 150 is minimized. For this reason, as shown in FIG. 10, in this embodiment, the surface where the boss 155 contacts the arm 144 crosses the neutral surface IS and extends from the position α to the position β. In this embodiment, the thickness of the arm shown in FIG. 10 is 0.048 mm. From FIG. 11, if the caulking position is set within a range of ± 0.05 mm from the neutral plane IS, the amount of warpage is ± 0. It is about 01 mm and is an allowable range. The range of ± 0.05 mm corresponds to a range of about ± 10% of the arm thickness (± 0.048 mm). However, considering the variations in the manufacturing of the base plate 150, the crimping position _{P 11} in the range of ± 5% range for the thickness of the arm from the neutral plane IS (± 0.024 mm) are preferred.

FIG. 12 shows a control block diagram of the control system 160 of the HDD 100. The control system 160 is an example of control when the head 122 includes an inductive head and an MR head. The control system 160 of the HDD 100 includes a control unit 161, an interface 162, a hard disk controller (hereinafter referred to as “HDC”) 163, a write modulation unit 164, a read demodulation unit 165, a sense current control unit 166, and a head IC 167. It is embodied in the HDD 100 as a control board or the like. Of course, only the head IC 167 need not be configured integrally, such as being mounted on the carriage 140.

  The control unit 161 includes any processing unit such as CPU or MPU regardless of the name, and controls each unit of the control system 160. The interface 162 connects the HDD 100 to an external device such as a personal computer (hereinafter referred to as “PC”), which is a host device. The HDC 163 transmits the data demodulated by the read demodulation unit 165 to the control unit 161, transmits the data to the write modulation unit 164, and transmits the current value set by the control unit 161 to the sense current control unit 166. Or In FIG. 12, the control unit 161 servo-controls the spindle motor 106 and the carriage 140 (the motor thereof), but the HDC 163 may have such a servo control function.

  The write modulation unit 164 is supplied from the host device via the interface 162, for example, modulates data written to the disk 104 by the inductive head, and supplies the data to the head IC 162. The read demodulator 165 samples the data read by the MR head from the disk 104 and demodulates it into the original signal. The write modulation unit 164 and the read demodulation unit 165 may be grasped as an integral signal processing unit. The head IC 167 functions as a preamplifier. In addition, since any configuration known in the art can be applied to each part, the detailed structure is omitted here.

  In the operation of the HDD 100, the control unit 161 drives the spindle motor 106 to rotate the disk 104. An air flow accompanying the rotation of the disk 104 is wound between the slider 121 and the disk 104 to form a minute air film, and a buoyancy that floats from the disk surface acts on the slider 121. On the other hand, the suspension 130 applies an elastic pressing force to the slider 121 in a direction opposite to the buoyancy of the slider 121. Due to the balance between the buoyancy and the elastic force, the magnetic head unit 120 and the disk 104 are spaced apart from each other by a constant distance. As described above, since the amount of warping of the base frame 150 is suppressed, the elastic pressing force applied by the suspension 130, the posture, the flying height, the posture, the vibration characteristics, etc. of the slider 121 are close to the design values. The head 122 can be positioned with high accuracy by preventing the occurrence.

  Next, the control unit 161 controls the carriage 140 to rotate the carriage 140 around the support shaft 142 to cause the head 122 to seek on the target track of the disk 104. Although the present embodiment is a swing arm type in which the locus of the slider 121 draws an arc around the support shaft 142 in this way, the present invention does not prevent the application of a linear type in which the locus of the slider 121 is linear. Absent.

  At the time of writing, the control unit 161 receives data obtained from a host device such as a PC (not shown) via the interface 162, selects an inductive head, and transmits it to the write modulation unit 164 via the HDC 163. In response to this, the write modulation unit 164 modulates the data and then transmits the modulated data to the head IC 167. The head IC 167 amplifies the modulated data and supplies it to the inductive head as a write current. As a result, the inductive head writes data to the target track.

  At the time of reading, the control unit 161 selects the MR head, and transmits a predetermined sense current to the sense current control unit 166 via the HDC 163. In response to this, the sense current control unit 166 supplies the sense current to the MR head via the head IC 167. As a result, the MR head reads desired information from a desired track on the disk 104.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. Further, although the present embodiment has been described for the HDD, the present invention is also applicable to other types of magnetic disk devices (such as magneto-optical disk devices). Further, although the single head structure of the fourth arm 144 from the top shown in FIG. 3A has been described, FIG. 11 is substantially established for the uppermost arm 144 of FIG.

It is a top view which shows the internal structure of the hard disk drive as one Example of this invention. It is an expansion perspective view of the magnetic head part of the hard disk drive shown in FIG. 3A to 3C are a left side view and a plan view showing a detailed structure of the head stack assembly shown in FIG. 4 (a) and 4 (b) are a schematic plan view and a schematic cross-sectional view of a suspension to which a base plate is fixed. 5 (a) and 5 (b) are a schematic plan view and a schematic cross-sectional view of the base plate shown in FIGS. 4 (a) and 4 (b). It is a flowchart for demonstrating the manufacturing method of the baseplate shown to Fig.5 (a) and FIG.5 (b). It is the schematic plan view and schematic sectional drawing of the hollow of the baseplate shown to Fig.5 (a) and FIG.5 (b). It is a schematic sectional drawing for demonstrating the caulking fastening of the base plate and arm which are shown to Fig.5 (a) and FIG.5 (b). FIG. 9A to FIG. 9C are schematic cross-sectional views showing the structure of a conventional base plate. It is the elements on larger scale of the base plate crimped to the arm shown in FIG. It is a graph which shows the relationship between the distance of the crimping position of a base plate shown in FIG. 10, and a neutral surface, and the amount of curvature. FIG. 2 is a block diagram of a control system of the hard disk drive shown in FIG. 1.

Explanation of symbols

100 Magnetic disk unit (hard disk drive)
110 Head stack assembly 120 Magnetic head unit 130 Suspension 140 Carriage 144 Arm 150 Base plate

Claims (7)

A method of manufacturing a head stack assembly having a suspension for supporting a head, an arm for driving the head, and a base plate for attaching the suspension to the arm,
With the base plate having a boss having an opening inserted into the through hole of the arm, the base plate is formed by penetrating the opening of the boss in one direction in the through hole with a processing member larger than the opening. A step of caulking and fastening to the arm;
When the surface that halves the thickness of the arm is a neutral surface, after the caulking and fastening step, the first position that is the most upstream along the one direction among the positions where the base plate contacts the arm; 2. A method according to claim 1, wherein a caulking position, which is an intermediate position between the second most downstream positions, is within a range of ± 10% of the thickness of the arm from the neutral plane.   The method according to claim 1, wherein the caulking position is within ± 5% of the thickness of the arm from the neutral plane. A head stack assembly including a suspension that supports a head, an arm that drives the head, and a base plate that attaches the suspension to the arm,
The base plate is crimped to the through hole of the arm,
The head stack is characterized in that when the surface that halves the thickness of the arm is a neutral surface, the base plate has a boss that is crimped to the arm, and the boss is disposed across the neutral surface. Assembly.   When the surface that halves the thickness of the arm is a neutral surface, the first position that is the most upstream in the direction in which the caulking fastening working member moves among the positions where the base plate contacts the arm 4. The head stack assembly according to claim 3, wherein a caulking position that is an intermediate position between the second position and the most downstream second position is within a range of ± 10% of the thickness of the arm from the neutral surface. 5. .   5. The head stack assembly according to claim 4, wherein the caulking position is within a range of ± 5% of the thickness of the arm from the neutral plane.   3. A magnetic disk drive having a head stack assembly manufactured from the method according to claim 1.   6. A magnetic disk drive comprising the head stack assembly according to claim 3.