Magnetic disk device

Abstract

The magnetic disk device is a 3.5-inch magnetic disk device in which magnetic disks composed of an aluminum alloy substrate are mounted. The thickness (Td) of the stacked magnetic disks is 0.3 mm or more and 0.6 mm or less, the number (N) of the magnetic disks is 10 or more and 16 or less, and the outer diameter (2Rso) of the spacer disposed between the magnetic disks is 35 mm or more and 65 mm or less. The outer diameter (2Rso) (mm) of the spacer satisfies 2Rso ≧ -60Td + 70 and 2Rso ≦ -0.5N + 16.5 2 + 16.5N - 73.

Description

Technical Field

[0001] This invention relates to disk drives. Background Technology

[0002] With the widespread use of smartphones and smart home appliances, the amount of data used by each person has increased. This massive amount of data is stored on hard disk drives (HDDs) in data centers via the internet. To store such a large amount of data, high-capacity hard disk drives are required.

[0003] As an example of achieving high capacity in disk drives, there is a technological trend towards increasing the number of disks mounted in the disk drive, thereby expanding the data area of ​​each disk drive. To mount multiple disks in a disk drive, annular spacers are arranged between the disks. When using multiple substrates, the spacers also function to maintain a certain distance between the substrates. For example, Patent Document 1 discloses a glass spacer with an average surface roughness of 0.001 to 0.3 μm for the portion in contact with the disk.

[0004] [Prior Technology Documents]

[0005] [Patent Literature]

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-307452 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] Because the size of disk drives is standardized, improvements such as reducing the thickness of the disk are necessary to increase the number of disks that can be mounted. However, reducing the thickness of the disk reduces its rigidity, shock resistance, and vibration resistance. In other words, there is a dilemma between increasing the capacity of disk drives and improving their shock and vibration resistance.

[0009] This disclosure was made in view of such actual circumstances, and its purpose is to provide a disk device with excellent shock resistance and flutter resistance, and a large data area within the disk device.

[0010] [Technical solutions used to address technical problems]

[0011] To achieve the above objectives, the disk device of the first aspect of the present invention...

[0012] It is a 3.5-inch disk drive equipped with a disk made of an aluminum alloy substrate, characterized in that,

[0013] The thickness Td of the stacked disks is 0.3mm to 0.6mm, the number of disks N is 10 to 16, and the outer diameter 2Rso of the spacers disposed between the disks is 35mm to 65mm.

[0014] The outer diameter 2Rso (mm) of the spacer satisfies 2Rso ≥ -60Td + 70 and 2Rso ≤ -0.5N. 2 +16.5N-73.

[0015] It can be that the thickness Td of the disk is 0.47mm or more and 0.55mm or less, the number of disks N is 10, the outer diameter 2Rso of the spacer is 38mm or more and 42mm or less, the thickness of the spacer is 1.5mm or more, and the power consumption during startup is excellent.

[0016] To achieve the above objectives, the disk device of the second aspect of the present invention...

[0017] It is a 3.5-inch disk drive equipped with a disk made of a glass substrate, characterized in that,

[0018] The thickness Td of the stacked disks is 0.3mm to 0.6mm, the number of disks N is 10 to 16, and the outer diameter 2Rso of the spacers disposed between the disks is 35mm to 65mm.

[0019] The thickness Td of the disk is between 0.3 mm and 0.49 mm, and the outer diameter 2Rso (mm) of the spacer satisfies 2Rso ≥ -74Td + 69.3 and 2Rso ≤ -0.42N. 2 +14.8N-63.1.

[0020] It can be that the thickness Td of the disk is 0.37mm or more and 0.41mm or less, the number of disks N is 10, the outer diameter 2Rso of the spacer is 39mm or more and 42mm or less, the thickness of the spacer is 1.6mm or more, and the power consumption during startup is excellent.

[0021] Recording can be done using either heat-assisted magnetic recording or microwave-assisted magnetic recording.

[0022] [Invention Effects]

[0023] According to the present invention, a disk drive with excellent shock resistance and flutter resistance, and a large data area within the disk drive can be provided. Attached Figure Description

[0024] Figure 1 (A) is a top view of the disk device according to the embodiment. Figure 1(B) is a side view of the disk device.

[0025] Figure 2 This is a cross-sectional view showing the disk substrate and spacers included in the disk device according to the embodiment.

[0026] Figure 3 This is a perspective view showing the disk substrate and spacers included in the disk device according to the embodiment.

[0027] Figure 4 This is an enlarged cross-sectional view showing the disk substrate and spacers included in the disk device according to the embodiment.

[0028] Figure 5 This diagram shows that an impact has been applied to the disk substrate of the disk device in the embodiment.

[0029] Figure 6 This is a graph showing a comparison between the measured and calculated values ​​of the substrate deflection in the embodiment.

[0030] Figure 7 This is a graph showing the relationship between the outer diameter of the spacer of each thickness in the disk of the embodiment and the amount of deflection.

[0031] Figure 8 This is a graph showing the relationship between the outer diameter of the spacers and the quality of the data area for each number of disks in the embodiment.

[0032] Figure 9 This is a graph showing the relationship between the outer diameter of the spacer of each thickness in the disk of the embodiment and the amount of deflection.

[0033] Figure 10 This is a graph showing the relationship between the outer diameter of the spacers and the quality of the data area for each number of disks in the embodiment. Detailed Implementation

[0034] Hereinafter, a disk drive (HDD) and spacer according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0035] The disk drive 100 in this embodiment is a box-type recording and playback device, such as... Figure 1 (A) and Figure 1 As shown in (B), it includes: a housing 10, a base 20, multiple disks 30 arranged in an overlapping configuration, a head stack assembly 40, a voice coil motor 50, a ramp loading system 60, a clamp 70, a spindle motor (not shown), and other necessary components such as a circuit board. Additionally, as... Figure 2 and Figure 3 As shown, the disk drive 100 includes a plurality of spacers 80 disposed between a plurality of disks 30 and a hub 90 that rotates the plurality of disks 30 about a rotation axis Z.

[0036] return Figure 1 The dimensions of the disk device 100 are determined by common standards. For example, for data centers, a 3.5-inch disk device with dimensions conforming to a standard such as SFF-8301 is suitable. In this standard, the height H of the housing 10 is set to 26.1 mm, the width W is set to 101.6 mm, and the depth D is set to 147 mm.

[0037] The housing 10 is generally made of metal and has a cubic box shape with one side open. The necessary components such as the base 20, disk 30, head stack assembly 40, voice coil motor 50, ramp loading 60, clamp 70, spindle motor and circuit board are sealed by a top cover (not shown).

[0038] The base 20 is located at the bottom of the housing 10 and is the part that houses the voice coil motor 50, the spindle motor, and the circuit board. In many cases, the base 20 and the housing 10 are an integral unit.

[0039] like Figure 2 and Figure 3 As shown, the disk 30 is a disk-shaped medium for magnetically recording information, composed of a substrate, a base layer, a magnetic layer, a protective layer, and a lubricating layer, and rotates around the rotation axis Z. As a magnetic recording method, perpendicular magnetic recording (PMR) and shingled magnetic recording (SMR) are preferred. To achieve further high capacity, technologies such as heat-assisted magnetic recording (HAMR) and microwave-assisted magnetic recording (MAMR) have been developed. As a substrate, an aluminum alloy substrate or a glass substrate is preferred. Details regarding aluminum alloy substrates and glass substrates will be explained later.

[0040] The thickness Td of the disk 30 is 0.3 mm to 0.6 mm, the outer diameter 2Rd is 95 mm or 97 mm, and the inner diameter is 25 mm. Furthermore, the number N of disks 30 included in the disk drive 100 of this embodiment is 10 to 16. When the disk 30 is made of a glass substrate, the thickness Td of the disk 30 is preferably 0.3 mm to 0.49 mm. As an example of achieving high capacity in the disk drive 100, there is a technique that increases the number of disks 30 mounted, thereby expanding the data area of ​​each disk drive 100. However, as described above, the size of the disk drive 100 is determined by standards, and the space for mounting the disks 30 is limited. Therefore, in order to increase the number of mounted disks 30, the thickness of the disks 30 is reduced.

[0041] return Figure 1 The head stack assembly 40 has an arm 41 and a head 42 mounted on the front end of the arm 41. In the case of recording by HAMR, a laser element is mounted on the head 42, and in the case of storage by MAMR, a microwave generating element is mounted on the head 42.

[0042] The voice coil motor 50 is a drive motor that rotates the magnetic head stack assembly 40.

[0043] The rampload 60 is a resin component designed to retract the head 42 when the disk drive 100 is not in operation. It is mounted on the outer periphery of the disk drive 30 at the position closest to the disk drive 30.

[0044] The clamp 70 is used to secure the disk 30 to the hub 90.

[0045] like Figure 2 and Figure 3 As shown, the spacer 80 is an annular thin plate disposed between the plurality of disks 30. By distributing the spacer 80 between the plurality of disks 30, the disks 30 are securely fixed to the hub 90 of the spindle motor by the clamp 70. The function of the spacer 80 is to ensure the spacing between the plurality of disks 30 and to transmit the rotational driving force of the hub 90 to the disks 30 that are not in direct contact with the hub 90 or the clamp 70 by contacting and closely fitting with the disks 30.

[0046] The outer diameter 2Rso of the spacer 80 is 35 mm or more and 65 mm or less. This allows for the expansion of the data area within the disk drive 100 while maintaining its shock and vibration resistance. Shock and vibration resistance will be explained later. When the disk drive 100 is equipped with a disk 30 made of an aluminum alloy substrate, the outer diameter 2Rso (mm) of the spacer 80 preferably satisfies 2Rso ≥ -60Td + 70 and 2Rso ≤ -0.5N. 2+16.5N-73. When the disk drive 100 is equipped with a disk 30 made of a glass substrate, the outer diameter 2Rso (mm) of the spacer 80 preferably satisfies 2Rso≧-74Td+69.3 and 2Rso≦-0.42N. 2 +14.8N-63.1.

[0047] Regarding the thickness Ts of the spacer 80, a narrower spacing between the disks 30 allows for more disks 30 to be mounted within a limited space, which is preferable. However, space is required on the surface of the disks 30 for the head stack assembly 40 to operate. In particular, in the high-capacity technologies of HAMR and MAMR described above, a laser element needs to be mounted on the head 42 for HAMR recording, and a microwave generating element needs to be mounted on the head 42 for MAMR storage. Miniaturization of the head stack assembly 40 is not easy. The spacing between the disks 30, i.e., the thickness Ts of the spacer 80, needs to be at least 1 mm, preferably 1.5 mm, and more preferably 1.6 mm or more.

[0048] The spacer 80 is preferably shaped with low flatness on both surfaces. Furthermore, it is preferable to chamfer the boundaries between the surface of the spacer 80 and its inner and outer peripheral end faces (hereinafter referred to as the inner and outer peripheral portions of the spacer) for the purpose of deburring. This is because, during the stacking of the disk 30 and the spacer 80, burrs on the inner and outer peripheral portions of the spacer 80 may come into contact with the disk 30 and potentially cause damage. Figure 4 As shown, the spacer 80 preferably has a chamfered portion 81. If we denote the outer radius of the spacer 80 as Rso, the inner radius of the spacer 80 as Rsi, the length of the chamfered portion 81 of the outer periphery of the spacer 80 as Lso, the length of the chamfered portion 82 of the inner periphery of the spacer 80 as Lsi, the outer radius of the contact portion 83 between the spacer 80 and the disk as Rsso, and the inner radius of the contact portion 83 between the spacer 80 and the disk 30 as Rssi, then Rsso = Rso - Lso, and Rssi = Rsi + Lsi. The radial length of the contact portion 83 is Rst = Rsso - Rssi. Since the chamfered portions 81 and 82 of the spacer 80 do not contribute to the contact with the disk 30 and do not contribute to the transmission of the rotational driving force of the hub 90 to the disk 30, the lengths Lso and Lsi of the chamfered portions 81 and 82 of the spacer 80 are preferably as small as possible, specifically preferably less than 0.1 mm.

[0049] The spacer 80 is preferably made of a material with a smaller difference in the coefficients of thermal expansion between itself and the disk 30. If the difference in their coefficients of thermal expansion is large, changes in ambient temperature during disk 30 operation can cause misalignment between the spacer 80 and the surface of the disk 30, leading to read / write errors. When the disk 30 is made of an aluminum alloy substrate, the spacer 80 is preferably made of aluminum alloy. When the disk 30 is made of a glass substrate, the spacer 80 is preferably made of glass, stainless steel, titanium, etc. Furthermore, to prevent static electricity on the disk 30 and the spacer 80, the spacer 80 is preferably conductive. When the spacer 80 is made of glass, it is preferable to have a metal film such as Ni-P plating on the surface and sides of the glass spacer 80.

[0050] The case where multiple disks 30 are mounted within the disk drive 100 will be explained. For example... Figure 2 and Figure 3 As shown, the outer radius of the disk is denoted as Rd, the thickness of the disk as Td, the outer radius of the spacer as Rso, the thickness of the spacer 80 as Ts, and the stacking height of the disk and the spacer as T. The inner diameter of the disk 30 is equal to the inner diameter of the spacer 80, and the inner radius of the disk = the inner radius of the spacer Rsi. The inner diameter of the disk 30 and the inner diameter of the spacer 80, 2Rsi, is, for example, 25 mm.

[0051] Here, we consider a disk drive 100 with a housing 10 height H of 26.1 mm that conforms to SFF-8301. When N disks 30 of thickness Td and (N-1) spacers 80 of thickness Ts are alternately stacked in the disk drive 100, the stacking height T = N × Td + (N-1) × Ts needs to be less than 26.1 mm. However, besides the disks 30 and spacers 80, the disk drive 100 also houses components such as a base 20, circuit board, spindle motor, clamp 70, hub 90, and top cover within the device space. Therefore, the stacking height T of the disks 30 and spacers 80 is preferably 20 mm or less, more preferably 19 mm or less. As described above, the lower limit of the thickness Td of the disks 30 is 0.3 mm, the lower limit of the thickness Ts of the spacers 80 is 1 mm, and the upper limit of the stacking height T of the disks 30 and spacers 80 is 20 mm. Therefore, the upper limit of the number of disks N is 16. In addition, in order to achieve high capacity of disk device 100, the number of disks N in disk 30 is 10 or more.

[0052] The hub 90 has a cylindrical shape with a small-diameter portion 91 and a large-diameter portion 92 connected in the direction of the rotation axis Z, and rotates around the rotation axis Z via a spindle motor. The diameter of the small-diameter portion 91 is the same as the inner diameter of the disk 30 and the inner diameter 2Rsi of the spacer 80. The large-diameter portion 92, together with the clamp 70, clamps and fixes the disk 30 and the spacer 80.

[0053] As described above, the disk 30 is a disk-shaped medium used for magnetically recording information, and is composed of a substrate, a base layer, a magnetic layer, a protective layer, and a lubricating layer. The substrate is preferably an aluminum alloy substrate or a glass substrate.

[0054] (Aluminum alloy substrate)

[0055] Previously used Al-Mg alloys, such as JIS5086, have high strength and are suitable for use with aluminum alloy substrates. Alternatively, Al-Fe alloys have high rigidity and are therefore suitable for use.

[0056] Specifically, Al-Mg alloys are aluminum alloys containing Mg: 1.0 to 6.5% by mass, and one or more of Cu: less than 0.070% by mass, Zn: less than 0.60% by mass, Fe: less than 0.50% by mass, Si: less than 0.50% by mass, Cr: less than 0.20% by mass, Mn: less than 0.50% by mass, and Zr: less than 0.20% by mass, with the remainder consisting of aluminum and unavoidable impurities and other trace elements.

[0057] Al-Fe alloys are aluminum alloys containing Fe as an essential element and one or two of Mn and Ni as optional elements, with the total content of Fe, Mn and Ni being 1.00 to 7.00% by mass. Furthermore, they contain one or more of Si: less than 14.0% by mass, Zn: less than 0.7% by mass, Cu: less than 1.0% by mass, Mg: less than 3.5% by mass, Cr: less than 0.30% by mass, and Zr: less than 0.20% by mass. The remainder consists of aluminum and unavoidable impurities and other trace elements.

[0058] The manufacturing method of aluminum alloy substrate is described below.

[0059] First, ingots are produced using a semi-continuous casting method, followed by hot and cold rolling to produce plates of the desired thickness. Alternatively, plates are produced using continuous casting, followed by cold rolling to produce plates of the desired thickness. The ingots may also be heat-treated to homogenize the microstructure. Heat treatment may also be applied to the plates before, during, or after cold rolling to improve machinability.

[0060] Next, the sheet metal prepared as described above is punched using a stamping press to produce a disc-shaped blank with the desired inner and outer diameter dimensions. Then, to reduce the flatness of the blank, the blanks are stacked on top of each other, and a load is applied to the stacked blanks for heat treatment.

[0061] Next, the inner and outer diameter portions of the blank are machined using a lathe to produce a T-substrate with a chamfered portion having the desired inner diameter, outer diameter, and length. Furthermore, the surfaces of both sides of the blank can be machined to produce a T-substrate with the desired thickness. Furthermore, the T-substrate can be heat-treated to remove machining deformation caused within the material during machining.

[0062] Next, the surfaces of both sides of the T-substrate are ground using a grinding machine to produce a G-substrate of the desired thickness. Furthermore, in order to remove the processing deformation caused within the material by the grinding process, the G-substrate may also be subjected to heat treatment.

[0063] Next, an M-substrate is fabricated with a plating film of the desired thickness on all surfaces of the G-substrate, including the surface, side surfaces, and chamfered surfaces. First, the G-substrate is pretreated to improve the adhesion of the plating. Then, a plating process is performed. Ni-P electroless plating is preferably used. Furthermore, the M-substrate may be subjected to a heat treatment to remove internal stress from the Ni-P electroless plating.

[0064] Next, the surfaces of both sides of the M substrate are ground using a grinding machine to produce a substrate of the desired thickness, i.e., an aluminum alloy substrate. The minimum thickness of the aluminum alloy substrate produced by this method is 0.3 mm. This is because the thickness of the component called the carrier of the aluminum alloy substrate is maintained during grinding. The thickness of the carrier can be arbitrarily chosen as long as it is greater than or equal to the thickness of the aluminum alloy substrate being processed; however, if the carrier is too thin, its strength will be insufficient, and it will break during the grinding process. From the viewpoint of carrier strength, the thickness of the carrier is preferably 0.3 mm or more. Therefore, the minimum thickness of the aluminum alloy substrate being processed is 0.3 mm. Furthermore, a carrier made of resin such as aramid resin or epoxy resin is preferred. For the purpose of improving strength, fibrous reinforcing materials such as carbon fiber or glass fiber are sometimes also included.

[0065] Next, a base layer, a magnetic layer, a protective layer, and a lubricating layer are formed on the surface of the aluminum alloy substrate. Thus, the disk 30 is obtained.

[0066] (Glass substrate)

[0067] Aluminosilicate glass has high hardness and is suitable for use as a glass substrate. Specifically, aluminosilicate glass has the following composition: SiO2: 55-70% by mass as the main component, containing one or more of the following: Al2O3: less than 25% by mass, Li2O: less than 12% by mass, Na2O: less than 12% by mass, K2O: less than 8% by mass, MgO: less than 7% by mass, CaO: less than 10% by mass, ZrO2: less than 10% by mass, and TiO2: less than 1% by mass. The remainder consists of unavoidable impurities and other trace elements.

[0068] The manufacturing method of the glass substrate will be described below.

[0069] First, glass raw materials with a specified chemical composition are dissolved, and the molten block is pressed from both sides using a direct pressing method to produce a glass sheet with the desired thickness. The production of the glass sheet is not limited to the direct pressing method; it can also be done using float glass, melting glass, redrawing glass, etc.

[0070] Next, the glass plate is rolled into a ring shape, and then the inner and outer diameter parts are ground to produce a ring-shaped glass plate with the desired inner diameter, outer diameter and chamfer length.

[0071] Next, the surfaces of both sides of the annular glass plate are ground using a grinding machine to produce an annular glass substrate with the desired thickness and flatness.

[0072] Then, the surfaces of both sides of the annular glass plate are ground using a grinding machine to produce a substrate, i.e., a glass substrate, of the desired thickness. Alternatively, chemical strengthening treatment using sodium nitrate solution, potassium nitrate solution, or similar agents can be performed during the grinding process.

[0073] The minimum thickness of the glass substrate produced by this method is 0.3 mm. This is because the thickness of the component called the carrier is maintained during grinding. The carrier thickness can be arbitrarily chosen as long as it is equal to or greater than the thickness of the glass substrate being processed; however, if the carrier is too thin, its strength will be insufficient, and it will break during the grinding process. From the viewpoint of carrier strength, the carrier thickness is preferably 0.3 mm or more. Therefore, the minimum thickness of the glass substrate being processed is 0.3 mm. Furthermore, a carrier made of resin such as aramid resin or epoxy resin is preferred. To improve strength, fibrous reinforcing materials such as carbon fiber or glass fiber are sometimes also included.

[0074] (Impact resistance)

[0075] like Figure 5As shown, when the disk drive 100 is subjected to an external impact, the disk 30 flexes and collides with, for example, a ramp load 60. As described above, the ramp load 60 is a resin component mounted on the outer periphery of the disk 30, closest to the disk 30, with the purpose of retracting the head 42 when the disk drive 100 is not in operation. If the disk 30 collides with the ramp load 60, a portion of the ramp load 60 may be damaged, resulting in foreign matter, or damage may occur to the disk 30, causing a malfunction. The higher the rigidity of the disk 30, the smaller the flexing, and the lower the probability of malfunction. That is, the higher the rigidity of the disk 30, the better its impact resistance.

[0076] (Flutter resistance)

[0077] During the operation of the disk drive 100, the disk 30 rotates at a high speed, for example, 7200 rpm. When the disk 30 rotates at high speed, turbulence occurs within the disk drive 30, causing it to vibrate. This vibration phenomenon is called flutter. If the disk 30 vibrates, the positional accuracy of the head 42 decreases, leading to read errors. The higher the rigidity of the disk 30, the smaller the vibration, and the lower the probability of read / write errors. That is, the higher the rigidity of the disk 30, the better its flutter resistance. Furthermore, it is known that a technique of filling the disk drive 100 with helium instead of air is used to reduce gas turbulence within the disk drive 100.

[0078] (Disk rigidity)

[0079] The shock resistance of disk 30 is represented by the amount of deflection of disk 30 when subjected to acceleration caused by an impact. The flutter resistance of disk 30 is represented by the amount of deflection of disk 30 when subjected to turbulence of gas generated by the high-speed rotation of disk 30. That is, the shock resistance and flutter resistance of disk 30 are determined by how easily disk 30 deflects.

[0080] The deflection of disk 30 can be considered using the following model: disk 30 is a circular plate with its inner circumference fixed in region AX. It bears a symmetrical vertical load relative to the center of the circular plate, and deflection of the axial object occurs on the rotation axis Z. As shown in "Handbook of Mechanical Engineering / Volume 4 Mechanics of Materials / Chapter 5 / Table 36-18", it can be calculated using the following formula 1.

[0081] [Formula 1]

[0082]

[0083]

[0084]

[0085] ω is the deflection of the circular plate, 2a is the diameter of the circular plate, 2b is the diameter of the inner circumference fixed part of the circular plate, r is the distance from the center of the circular plate, p is the load per unit area, and D = Eh. 3 / 12(1-ν 2 ): The bending stiffness of the plate, E is the Young's modulus of the circular plate, h is the thickness of the circular plate, and ν is the Poisson's ratio of the circular plate.

[0086] This and Figure 2 and Figure 3 Corresponding to the parameters within the disk drive 100 shown, the outer radius of the disk Rd = a, the outer radius of the contact portion between the spacer 80 and the disk 30 Rsso = b, the thickness of the disk 30 Td = h, and the load per unit area of ​​the disk 30 p = ρTd, where ρ is the density of the disk 30. Furthermore, the deflection ωmax at the outermost periphery of the disk 30 is obtained by substituting r = Rd. Reflecting these parameters, Equation 1 can be transformed into Equation 2. Furthermore, Figure 2 and Figure 5 The area AX shown is the region where the disk 30 is firmly fixed by the large diameter portion 92 of the hub 90, the contact surface of the spacer 80, and the clamp 70, and is considered to be a rigid body.

[0087] [Equation 2]

[0088]

[0089]

[0090]

[0091]

[0092] That is, the deflection ωmax at the outermost periphery of the disk 30 can be expressed as a function of the outer radius Rd of the disk 30, the thickness Td of the disk 30, the outer radius Rsso of the contact portion between the spacer 80 and the disk 30, the Young's modulus E of the disk 30, the density ρ of the disk 30, and the Poisson's ratio ν of the disk 30. Furthermore, Equation 1 and Equation 2 derived from Equation 1 are applicable not only to the disk 30, but also to all circular plates that fix the inner periphery, such as disk substrates and disks other than those used for disk applications.

[0093] The density ρ of the disk 30 or the disk substrate can be determined using the Archimedes method, and the Young's modulus E and Poisson's ratio ν can be determined using methods such as the ultrasonic pulse method. Furthermore, when the substrate of the disk 30 is made of an aluminum alloy substrate, since the aluminum alloy substrate is a composite of aluminum alloy and Ni-P plating, ρ, E, and ν depend on the thickness of the aluminum alloy and the thickness of the Ni-P plating. However, as mentioned above, ρ can be determined using the Archimedes method, and E and ν can be determined using methods such as the ultrasonic pulse method.

[0094] (Data area of ​​the disk device)

[0095] If we denote the data area on both sides of each disk as Sd, the number of disks mounted as N, the inner radius of the data area of ​​the disk as Rddi, and the outer radius of the data area of ​​the disk as Rddo, then the data area S within the disk device is calculated by the following formula 3.

[0096] [Formula 3]

[0097] (Power consumption during startup of disk device 100)

[0098] The lower the power consumption of the disk drive 100, the better. Here, we focus on the amount of work done by the 25mm diameter hub 90, which houses the spindle motor, during the startup of the disk drive 100, i.e., until the disk 30 reaches a steady state (e.g., 7200 rpm) from a stationary state. The work done by the hub 90 is to rotate the stack (a hollow cylinder) consisting of the disk 30 and the spacer 80 about the rotation axis Z, and this work is proportional to the inertial torque of the stack consisting of the disk 30 and the spacer 80. The angular acceleration of the disk until it reaches a steady state from a stationary state is set to a constant value.

[0099] First, as shown in "Handbook of Mechanical Engineering / Part 3 Mechanics / Chapter 2 Center of Gravity and Moment of Inertia / 2.2.5e Hollow Straight Cylinder", the moment of inertia Iz of the hollow straight cylinder can be calculated by the following formula 4.

[0100] [Formula 4]

[0101]

[0102] m is the mass of the hollow straight cylinder, R is the outer radius of the hollow straight cylinder, and r is the inner radius of the hollow straight cylinder. The moment of inertia Ids of the stack consisting of disk 30 and spacer 80 is the sum of the moment of inertia Id of disk 30 and the moment of inertia Is of spacer 80. Equation 5 is obtained by calculation using Equation 4.

[0103] [Formula 5]

[0104] I ds =I d +I s …(Equation 5)

[0105]

[0106]

[0107] md is the total mass of disk 30, ρ is the density of disk 30, N is the number of disks in disk 30, Td is the thickness of disk 30, Rd is the outer radius of disk 30, ms is the total mass of spacer 80, ρs is the density of spacer 80, N-1 is the number of spacers in spacer 80, Ts is the thickness of spacer, Rso is the outer radius of spacer 80, and Rsi is the inner radius of spacer = the inner radius of disk = 25mm.

[0108] Based on these parameters, it is possible to estimate the amount of work done by the hub 90 from the disk 30 to the steady state from the stop state, that is, the power consumed when the disk device 100 starts.

[0109] When the disk drive 100 is equipped with a disk 30 made of an aluminum alloy substrate, the thickness Td of the disk 30 is 0.47 mm to 0.55 mm, the number of disks N is 10, the outer diameter 2Rso of the spacer 80 is 38 mm to 42 mm, and the thickness Ts of the spacer 80 is 1.5 mm or more. As a result, the power consumption during startup is excellent.

[0110] When the disk drive 100 is equipped with a disk 30 made of a glass substrate, the thickness Td of the disk 30 is 0.37 mm or more and 0.41 mm or less, the number of disks N is 10, the outer diameter 2Rso of the spacer 80 is 39 mm or more and 42 mm or less, and the thickness Ts of the spacer 80 is 1.6 mm or more. As a result, the power consumption during startup is excellent.

[0111] As described above, according to the disk drive 100 and spacer 80 of this embodiment, by setting the outer diameter 2Rso of the spacer 80 to the aforementioned value, a high-capacity 3.5-inch disk drive 100 can be provided that expands the data area within the disk drive 100 without increasing the deflection of the disk 30, i.e., while maintaining the shock resistance and flutter resistance of the disk drive 100. Furthermore, by setting the thickness of the spacer 80 to the aforementioned value, a disk spacing suitable for HAMR or MAMR applications can be ensured. In addition, by setting the outer diameter 2Rso of the spacer 80, the thickness Td of the disk 30, and the number of disks N to the aforementioned values, a disk drive 100 with excellent power consumption during startup can be provided. Therefore, a disk drive 100 and spacer 80 with excellent shock resistance and flutter resistance and a large data area within the disk drive 100 can be provided. By mounting the disk drive 100 in a data center, it is possible to contribute to the high capacity of the data center. Furthermore, the ideas of this embodiment, such as suppressing disk deflection by increasing the outer diameter of the spacer 80 within the disk drive 100 and expanding the data area by increasing the number of disks mounted by reducing the thickness of the disk 30, are not limited to the 3.5-inch disk drive 100 and can be applied to disk drives 100 of all sizes. The type of disk 30 is not limited to disks 30 made of aluminum alloy substrates or glass substrates, and can be applied to all types of disks 30.

[0112] (Modified Example)

[0113] In the above embodiment, an example was described where the inner diameter 2Rsi of the disk 30 and the spacer 80 is 25 mm. The spacer 80 serves to ensure spacing between the multiple disks 30 and, through contact and tight bonding with the disks 30, transmits the rotational driving force of the hub 90 to the disks 30 that are not in direct contact with the hub 90 or the clamp 70. If these functions can be achieved, the inner diameter 2Rsi is not particularly limited. Figure 4 The aforementioned function can be achieved when the radial length Rst = Rsso - Rssi of the contact portion 83 of the spacer 80 is 7 mm or more. When the length Lso of the chamfered portion 81 of the spacer 80 is sufficiently small relative to the length Rst, the inner radius Rsi of the spacer 80 is preferably the outer radius Rso - 7 mm or less. In this case, it can be ensured that the radial length Rst = Rsso - Rssi of the contact portion 83 of the spacer 80 is 7 mm or more.

[0114] Example

[0115] The present invention will now be described in more detail based on embodiments, but the present invention is not limited thereto.

[0116] (Disk flex)

[0117] Regarding the deflection ωmax at the outermost periphery of disk 30, the measured value of the deflection ωmax of disk 30 is compared with the calculated value obtained by Equation 2. Equation 2 indicates that the actual deflection ωmax of disk 30 can be predicted.

[0118] First, an aluminum alloy ingot with Fe = 0.7 wt%, Mn = 0.9 wt%, Ni = 1.7 wt%, Si = 0.06 wt%, Zn = 0.3 wt%, Cu = 0.02 wt%, and the remainder consisting of aluminum and unavoidable impurities and other trace elements is produced by a semi-continuous casting method.

[0119] Next, the ingots produced by the semi-continuous casting method are subjected to homogenization heat treatment, hot rolling, and cold rolling to produce sheet metal. The sheet metal is then punched using a stamping press, stacked, and subjected to load and heat treatment to produce billets. The inner and outer diameters of the billets are machined using a lathe, and both surfaces are machined and ground to produce aluminum alloy substrates (G substrates). The inner diameter of the aluminum alloy substrate is 25 mm, and the outer diameter is 97 mm. Three types of aluminum alloy substrates with thicknesses of 0.604 mm, 0.480 mm, and 0.461 mm were produced.

[0120] For these aluminum alloy substrates, the deflection ωmax of the substrates was measured using an impact testing apparatus. The apparatus included a hub and fixture that held and secured the aluminum alloy substrate with spacers, and a sensor to measure the displacement at the outermost periphery of the substrate. The spacers were made of aluminum, with an outer diameter of 32 mm, an inner diameter of 25 mm, and a thickness of 1.7 mm. The aluminum alloy substrates were held in place by the spacers within the impact testing apparatus and subjected to an impact with an acceleration of 50 G and a duration of 3 ms. The deflection ωmax at the outermost periphery of the substrate caused by the impact was measured. The deflection ωmax was measured three times for each sample. Then, the average deflection ωmax of a substrate with a thickness of 0.461 mm was set as 100%, and the relative values ​​of the deflection ωmax for each substrate thickness were calculated.

[0121] Furthermore, if the deflection of the disk 30 caused by the impact is large, it may collide violently with components within the disk drive 100, such as with the ramp loading 60, causing damage to a portion of the ramp loading 60 and resulting in foreign objects, or causing damage to the disk 30, thus becoming a cause of failure. Therefore, the smaller the deflection of the disk 30, the better its impact resistance. The disk 30 is formed by forming a base layer, a magnetic layer, a protective layer, and a lubricating layer on an aluminum alloy substrate, and the deflection ωmax of the disk 30 can be approximately the same as the deflection ωmax of the aluminum alloy substrate.

[0122] Next, Equation 2 is used to calculate the deflection at the outermost periphery of the aluminum alloy substrate. Let the outer diameter of the aluminum alloy substrate be 2Rd = 97 mm, and the thickness of the aluminum alloy substrate be Td at three levels: 0.604 mm, 0.480 mm, and 0.461 mm. The outer diameter of the contact portion between the spacer 84 and the aluminum alloy substrate is 2Rsso = 31.8 mm, E = 79 GPa, and ρ = 2.7 g / cm³. 3 ν = 0.33. Then, the deflection of the plate with a thickness of 0.461 mm was set to 100%, and the relative value was calculated.

[0123] The measured and calculated values ​​of the deflection at the outermost periphery of the aluminum alloy substrate, obtained in this way, are shown below. Figure 6 The measured values ​​are roughly consistent with the calculated values. Equation 2 indicates that the actual deflection of disk 30 can be predicted.

[0124] (Impact resistance and flutter resistance)

[0125] Next, using commercially available disk drives as a reference, it is shown that the disk drive 100 can expand the data area within the disk drive while maintaining shock resistance and flutter resistance.

[0126] The outer radius Rd of the disk, the thickness Td of the disk, the outer radius Rso of the spacer, the thickness Ts of the spacer, and the outer radius Rsso of the contact part between the spacer and the disk of commercially available disk drives were measured using vernier calipers.

[0127] Shock resistance and flutter resistance are evaluated using Formula 2, which measures the amount of deflection at the outermost periphery of the disk. A relative evaluation is performed with the baseline deflection set to 100%, and instances below 100% are considered good.

[0128] The data area S within the disk drive 100 is calculated using Formula 3. Here, the inner radius Rddi of the data area S of the disk 30 is calculated as Rddo = the inner radius Rsi + 2mm of the spacer 80, and the outer radius Rddo of the data area S of the disk 30 is calculated as Rso - 2mm of the outer radius Rso - 2mm. A baseline data area S is set to 100% for relative evaluation, and cases with a value of 100% or higher are recorded as good.

[0129] The power consumption of the disk drive 100 during startup is calculated using Equation 5 based on the moment of inertia Ids of the stack consisting of the disk 30 and the spacer 80. A baseline moment of inertia Ids is set to 100% for relative evaluation. Examples with values ​​below 100% are considered preferred examples.

[0130] (Aluminum alloy substrate)

[0131] A Toshiba MG07ACA14TE disk, equipped with nine disks made of aluminum alloy substrates, each with an outer diameter of 95 mm and an inner diameter of 25 mm, was designated as reference A. Reference A, the example disks, and the comparative examples are shown in Table 1. The disks of reference A, the example disks, and the comparative examples were compared at E = 74 GPa and ρ = 2.8 g / cm³. 3 ν = 0.3, spacer with ρs = 2.7 g / cm 3 Perform the calculation.

[0132] [Table 1]

[0133]

[0134] [Table 2]

[0135]

[0136] The deflection of the disks in Examples 1-1 to 1-27 is below the baseline, and the data area within the disk device is above the baseline. Figure 7 In this diagram, the horizontal axis represents the disk thickness Td, and the vertical axis represents the outer diameter 2Rso of the spacer. Examples of disk deflection below the baseline are indicated by "good" (○), comparative examples exceeding the baseline are indicated by "bad" (×), and baseline A is indicated by "□". Furthermore, in... Figure 8 In this diagram, the horizontal axis represents the number of disks N, the vertical axis represents the outer diameter 2Rso of the spacer, and the data area within the disk device is used as the reference. Examples of the above are represented by ○, comparative examples of the smaller than the reference are represented by ×, and the reference A is represented by □.

[0137] Based on the above, in the case of a 3.5-inch disk drive equipped with a disk made of an aluminum alloy substrate, if the disk thickness Td = 0.3~0.6mm, the number of disks N = 10~16, and the outer diameter 2Rso of the spacer satisfies 2Rso≧-60Td+70 and 2Rso≦-0.5N 2 +16.5N-73 means the disk flex is below the baseline and the data area is above the baseline.

[0138] Preferably, the disk-to-disk distance is at least 1.5 mm to ensure the operation of the head stacking assembly for HAMR equipped with laser elements or the head stacking assembly for MAMR equipped with microwave generating elements, and the power consumption of the disk device during startup is below a certain threshold. Examples 1-1 to 1-9, indicated by ◎ in Table 1, correspond to this.

[0139] As shown in Table 2, the disks in Comparative Examples 1-1 to 1-7 exhibit greater flexural strength than the baseline, and have poor shock and flutter resistance. The data areas within the disk devices in Comparative Examples 1-8 to 1-18 are smaller than the baseline, thus preventing the achievement of high capacity.

[0140] (Glass substrate)

[0141] A Seagate Exos X16ST16000NM001G disk, equipped with nine 97mm outer diameter and 25mm inner diameter disks made of glass substrates, was designated as reference B. Reference B, along with the embodiments and comparative examples, are shown in Tables 3 and 4. The disks of reference B, the embodiments, and the comparative examples were compared using E = 83 GPa and ρ = 2.5 g / cm³. 3 ν = 0.23, spacer with ρs = 4.4 g / cm 3 Perform the calculation.

[0142] [Table 3]

[0143]

[0144] [Table 4]

[0145]

[0146] In Examples 2-1 to 2-30, the deflection of the disk is below the baseline, and the data area within the disk device is above the baseline. Figure 9 In this diagram, the horizontal axis represents the disk thickness Td, and the vertical axis represents the outer diameter 2Rso of the spacer. Examples of disk deflection exceeding the baseline are represented by ○, comparative examples less than the baseline are represented by ×, and the baseline B is represented by □. Figure 10 In this diagram, the horizontal axis represents the number of disks N, the vertical axis represents the outer diameter 2Rso of the spacer, and examples with the data area within the disk device as the reference are represented by ○, comparative examples with a smaller data area as the reference are represented by ×, and the reference B is represented by □.

[0147] Based on the above, in the case of a 3.5-inch disk drive equipped with a disk made of a glass substrate, if the disk thickness Td = 0.3 to 0.49 mm, the number of disks N = 10 to 16, and the outer diameter 2Rso of the spacer satisfies 2Rso ≥ -74Td + 69.3 and 2Rso ≤ -0.42N, then... 2 +14.8N-63.1 means the disk flex is below the baseline and the data area is above the baseline.

[0148] More preferably, to ensure a sufficient inter-disk distance of 1.6 mm or more for the operation of the head stacking assembly for HAMR equipped with a laser element or the head stacking assembly for MAMR equipped with a microwave generating element, the power consumption of the disk device during startup is below a certain threshold. Examples 2-1 to 2-7, indicated by ◎◎ in Table 3, correspond to this.

[0149] As shown in Table 4, the disks in Comparative Examples 2-1 and 2-3 to 2-5 exhibited greater flexural strength than the baseline, and showed poor shock and flutter resistance. The disk devices in Comparative Examples 2-6 to 2-12 had smaller data areas than the baseline, thus failing to achieve high capacity.

[0150] Furthermore, regarding the disk, the range of disk deflection below the baseline and the data area above the baseline, for both aluminum alloy substrates and glass substrates, is as follows.

[0151] It is a 3.5-inch disk drive equipped with a disk made of an aluminum alloy substrate or a glass substrate, wherein the thickness of the disk Td = 0.3~0.49mm, the number of disks N = 10~16, and the outer diameter 2Rso of the spacer satisfies 2Rso≧-60Td+70 and 2Rso≦-0.5N. 2 The region is +16.5N-73.

[0152] As described above, by setting the outer diameter 2Rso of the spacer 80 to the aforementioned values, a high-capacity 3.5-inch disk drive 100 can be provided by expanding the data area within the disk drive 100 without increasing the deflection of the disk 30, i.e., while maintaining the shock resistance and flutter resistance of the disk drive 100. Furthermore, by setting the outer diameter 2Rso of the spacer 80, the thickness Td of the disk 30, and the number of disks N to the aforementioned values, a disk drive 100 with excellent power consumption during startup can be provided.

[0153] Various embodiments and modifications can be made to this invention without departing from its broad spirit and scope. Furthermore, the above embodiments are illustrative of the invention and do not limit its scope. That is, the scope of the invention is defined not by the embodiments, but by the claims. Moreover, various modifications implemented within the scope of the claims and their equivalents are considered to be within the scope of this invention.

[0154] This application is based on Japanese Patent Application No. 2020-192623, filed on November 19, 2020. The entire description, claims, and drawings of Japanese Patent Application No. 2020-192623 are incorporated herein by reference.

[0155] [Explanation of reference numerals in the attached figures]

[0156] 10. Shell

[0157] 20 abutment

[0158] 30 disks

[0159] 31 Aluminum alloy substrate

[0160] 40 Head Stacking Assembly

[0161] 41 arms

[0162] 42 Head

[0163] 50 voice coil motor

[0164] 60 Slope loading

[0165] 70 Fixture

[0166] 80 spacers

[0167] 81, 82 Chamfered sections

[0168] 83 Contact Department

[0169] 90 rims

[0170] 91. Small diameter section

[0171] 92 Large diameter part

[0172] 100 disk drives

[0173] D depth

[0174] W width

[0175] H height

[0176] N sheets

[0177] Z-axis of rotation

[0178] AX area

[0179] ωmax deflection

[0180] Rd outer radius

[0181] Td, Ts thickness

[0182] T Stack Height

[0183] Rsi Rssi Rddi Inner Radius

[0184] Rso Rsso Rddo Outer radius

Claims

1. A disk drive, a 3.5-inch disk drive housing a disk made of an aluminum alloy substrate, characterized in that, The thickness Td of the stacked disks is 0.3mm to 0.6mm, the number of disks N is 10 to 16, and the outer diameter 2Rso of the spacer disposed between the disks is 35mm to 65mm. The outer diameter 2Rso (mm) of the spacer satisfies 2Rso ≥ -60Td + 70 and 2Rso ≤ -0.5N. 2 +16.5N -73.

2. The disk drive as claimed in claim 1, characterized in that, The thickness Td of the disk is 0.47mm to 0.55mm, the number of disks N is 10, the outer diameter 2Rso of the spacer is 38mm to 42mm, the thickness of the spacer is 1.5mm or more, and the power consumption during startup is excellent.

3. The disk drive as claimed in claim 1 or 2, characterized in that, Recording is performed using either heat-assisted magnetic recording or microwave-assisted magnetic recording.

4. A disk drive, a 3.5-inch disk drive housing a disk made of a glass substrate, characterized in that, The number of disks N in the stacked configuration is 10 to 16, and the outer diameter 2Rso of the spacer disposed between the disks is 35 mm to 65 mm. The thickness Td of the disk is between 0.3 mm and 0.49 mm, and the outer diameter 2Rso (mm) of the spacer satisfies 2Rso ≥ -74Td + 69.3 and 2Rso ≤ -0.42N. 2 +14.8N -63.

1.

5. The disk drive as claimed in claim 4, characterized in that, The thickness Td of the disk is 0.37mm to 0.41mm, the number of disks N is 10, the outer diameter 2Rso of the spacer is 39mm to 42mm, the thickness of the spacer is 1.6mm or more, and the power consumption during startup is excellent.

6. The disk drive as claimed in claim 4 or 5, characterized in that, Recording is performed using either heat-assisted magnetic recording or microwave-assisted magnetic recording.

Images