Magnetic recording device and method for manufacturing the same

Abstract

The objective is to provide a magnetic recording device and a method for manufacturing the same that can suppress the deterioration of the head and recording medium and maintain constant performance over a long period of time. [Solution] According to the embodiment, the magnetic recording device comprises a housing with an internal dew point of 5°C or less, a disk-shaped recording medium provided inside the housing, and a magnetic head provided inside the housing for performing information processing on the recording medium.

Description

Technical Field

[0001] Embodiments of this invention relate to a magnetic recording device and a method of manufacturing the magnetic recording device.

Background Art

[0002] As a magnetic recording device, a magnetic recording device using a magnetic head of a heat assisted magnetic recording (HAMR) method has been proposed. HAMR is a technique for increasing the recording capacity by heating a recording medium to a temperature equal to or higher than the Curie temperature (Tc) by a heating source such as a laser during recording.

[0003] In heat assisted magnetic recording, although it is local, high temperature regions occur in the head and the recording medium. Therefore, the environment inside the magnetic recording device affects the deterioration modes of the head and the recording medium. For example, moisture contained in the magnetic recording device can cause various deterioration modes such as corrosion of the head or decomposition of the lubricant of the recording medium to generate acid in a high temperature state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the embodiments of the present invention is to provide a magnetic recording apparatus and a method for manufacturing the same that can suppress the deterioration of the head and recording medium and maintain constant performance over a predetermined period of time. [Means for solving the problem]

[0006] According to one embodiment, the magnetic recording device comprises a housing with an internal dew point of 5°C or less, a disk-shaped recording medium provided inside the housing, and a magnetic head provided inside the housing for performing information processing on the recording medium. It is equipped with. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is an exploded perspective view of a hard disk drive (HDD) according to the first embodiment, showing the top cover disassembled. [Figure 2] Figure 2 is a schematic side view showing the tip of the suspension assembly and the magnetic head in the HDD. [Figure 3] Figure 3 is a cross-sectional view showing an enlarged view of the head portion of the magnetic head. [Figure 4] Figure 4 is a cross-sectional view showing an enlarged view of the recording head and heat assist element portion of the magnetic head. [Figure 5] Figure 5 is a block diagram that schematically shows the overall configuration of the HDD. [Figure 6] Figure 6 shows the relationship between relative humidity and dew point in the aforementioned HDD. [Figure 7] Figure 7 is an enlarged cross-sectional view showing the head portion of the magnetic head in the HDD according to the second embodiment. [Figure 8] Figure 8 is a cross-sectional view showing an enlarged view of the recording head and electric field assist element portion of the magnetic head. [Modes for carrying out the invention]

[0008] A magnetic recording apparatus according to an embodiment will be described below with reference to the drawings. Furthermore, the disclosure is merely an example, and any modifications that can be easily conceived by a person skilled in the art while maintaining the spirit of the invention are naturally included within the scope of the present invention. In addition, the drawings may schematically represent the size, shape, etc. of each part in order to clarify the explanation, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0009] (First Embodiment) A hard disk drive (HDD) according to the first embodiment will be described in detail as a magnetic recording device. Figure 1 is a disassembled perspective view of the HDD according to the first embodiment, showing the cover removed. As shown in Figure 1, the HDD has a roughly rectangular enclosure 10. The enclosure 10 has a rectangular box-shaped base 12 with an open top, an inner cover 14 that is screwed to the base 12 by a plurality of screws 13 and closes the upper end opening of the base 12, and an outer cover (top cover) 11 that is placed on top of the inner cover 14 and whose peripheral edge is welded to the base 12. The base 12 has a rectangular bottom wall 12a that faces the inner cover 14 with a gap between them, and side walls 12b that are erected along the periphery of the bottom wall 12a, and is integrally molded from, for example, an aluminum alloy. The side walls 12b include a pair of opposing long side walls and a pair of opposing short side walls. Roughly rectangular frame-shaped fixing ribs 12c are provided protruding from the upper end surface of the side walls 12b.

[0010] The inner cover 14 is formed in the shape of a rectangular plate, for example, from stainless steel. The inner cover 14 is fixed to the inside of the fixing rib 12c by screws 13 at its periphery to the upper surface of the side wall 12b. The outer cover 11 is formed in the shape of a rectangular plate, for example, from aluminum. The outer cover 11 is formed to have a planar dimension slightly larger than that of the inner cover 14. The outer cover 11 is fixed to the base 12 in an airtight manner by welding its periphery all the way around to the fixing rib 12c of the base 12.

[0011] Ventilation holes 31 and 33 that communicate the inside and the outside of the housing 10 are formed in each of the inner cover 14 and the outer cover 11. The air inside the housing 10 is exhausted through the ventilation holes 31 and 33, and further, a low-density gas (inert gas) having a lower density than air, for example, helium (He), is enclosed in the housing 10 through these ventilation holes 31 and 33. For example, a seal (sealing body) 35 is attached to the outer surface of the outer cover 11 so as to block the ventilation hole 33. In the present embodiment, the low-density gas contains, for example, about 5% oxygen. The oxygen ratio (oxygen concentration) is preferably set in the range of 1% or more and less than 20%.

[0012] A plurality of, for example, 10 magnetic disks 18 as disk-shaped recording media and a spindle motor (SPM) 19 as a drive motor that supports and rotates the magnetic disks 18 are provided in the housing 10. The spindle motor 19 is disposed on the bottom wall 12a. Each magnetic disk 18 is formed, for example, in a disk shape with a diameter of 96 mm (3.5 inches). Each magnetic disk 18 has a substrate made of a non-magnetic material, for example, glass or aluminum, and magnetic recording layers formed on the upper and lower surfaces of the substrate.

[0013] The magnetic disks 18 are coaxially fitted to a hub, which will be described later, of the spindle motor 19, and are further clamped by a clamp spring 20. The plurality of magnetic disks 18 are rotated at a predetermined rotational speed by the spindle motor 19. Note that the number of mounted magnetic disks 18 is not limited to 10, and may be 9 or less, or 11 or more.

[0014] Inside the housing 10, there are provided a plurality of magnetic heads 17 for recording and reproducing information with respect to the magnetic disk 18, and an actuator assembly 22 that supports these magnetic heads 17 so as to be movable with respect to the magnetic disk 18. Further, inside the housing 10, there are provided a voice coil motor (VCM) 24 for rotating and positioning the actuator assembly 22, a ramp load mechanism 23 for holding the magnetic head 17 at an unload position where the magnetic head 17 is separated from the magnetic disk 18 when the magnetic head 17 moves to the outermost circumference of the magnetic disk 1, a substrate unit (FPC unit) 21 on which electronic components such as a conversion connector are mounted, a spoiler 71, and a circulation filter F. The ramp load mechanism 23 has a ramp 80.

[0015] A humidity sensor HS for detecting the relative humidity inside the housing 10 is provided inside the housing 10. The relative humidity inside the housing 10 is adjusted to 3% or less. Furthermore, inside the housing 10, a moisture absorbent (desiccant) M, for example, a moisture absorbent M with excellent moisture absorption such as zeolite, calcium oxide, silica gel, etc., is arranged. By adjusting the amount of the moisture absorbent M, the dew point inside the housing 10 is set to 5°C or less. More specifically, in a temperature range of at least 25 to 40°C, the inside of the housing 10 is set to be below the environmental temperature and the dew point is 5°C or less. In a temperature range of at least -5 to 60°C, it is preferable that the dew point inside the housing 10 is below the environmental temperature and 5°C or less.

[0016] A printed circuit board 41 is screwed to the outer surface of the bottom wall 12a of the base 12. The printed circuit board 41 constitutes a control unit that controls the operation of the spindle motor 19, the operation of the VCM 24, and the operation of the magnetic head 17.

[0017] As shown in Figure 1, the actuator assembly (sometimes referred to as a head stack assembly: HSA) 22 comprises an actuator block 29 having a through hole 26, a bearing unit 28 provided in the through hole 26, a plurality of arms 32 extending from the actuator block 29, for example, 11 arms, a suspension assembly (sometimes referred to as a head gimbal assembly: HGA) 30 attached to each arm 32, and a magnetic head 17 supported by the suspension assembly 30. A support shaft (pivot), not shown, is erected on the bottom wall 12a of the base 12. The actuator block 29 is rotatably supported around the support shaft by the bearing unit 28. The actuator assembly 22 has a support frame (not shown) that extends from the actuator block 29 in the opposite direction to the arm 32, and this support frame supports the voice coil, which forms part of the VCM 24.

[0018] Figure 2 is a schematic side view showing the tip of the suspension assembly 30 and the magnetic head 17. As shown in Figure 2, the suspension assembly 30 includes a base plate (not shown) attached to the arm 32, an elongated leaf spring-shaped load beam 38 extending from the base plate, and an elongated strip-shaped flexure (wiring member) 40. The flexure 40 has a displaceable gimbal section 42, on which the magnetic head 17 is mounted.

[0019] The magnetic head 17 is configured as a levitation head and has a substantially rectangular slider 15 and a head portion 16 formed at the end of the slider 15. The head portion 16 is formed of multiple layers of thin film. The slider 15 has a substantially rectangular disk-facing surface (air bearing surface (ABS)) 43 that faces the surface of the magnetic disk 18 and a back surface attached to the gimbal portion 42. A laser oscillator, such as a laser diode unit (LDU) 25 that functions as a light source, is fixed to the back surface of the slider 15. The slider 15 is maintained in a state where it is floating a predetermined amount above the surface of the magnetic disk 18 by the airflow generated between the disk surface and the ABS 43 due to the rotation of the magnetic disk 18.

[0020] As shown in Figure 2, the magnetic disk 18 has a substrate 101 made of a non-magnetic material formed in the shape of a disc. A heat sink layer 102, a crystal orientation layer 103, a magnetic recording layer 104 having magnetic anisotropy perpendicular to the surface of the magnetic disk 18, and a protective layer 105 with a lubricant 106 (see Figure 4) applied to its surface are sequentially laminated on the upper and lower surfaces of the substrate 101. The crystal orientation layer 103 is provided to improve the orientation of the magnetic recording layer 104. The heat sink layer 102 is placed below the crystal orientation layer 103 to suppress the spread of the heated area.

[0021] Figure 3 is a cross-sectional view showing an enlarged view of the head portion 16 of the magnetic head 17 and the magnetic disk 18. As shown in Figure 3, the head unit 16 has a read head (sometimes referred to as a regeneration element) 54 and a write head (sometimes referred to as a recording element) 58 formed by a thin-film process on the trailing end 15b of the slider 15. The read head 54 and the write head 58 are covered with a non-magnetic protective insulating film 53, except for the portion exposed to the ABS 43 of the slider 15. The protective insulating film 53 forms the outer shape of the head unit 16.

[0022] The magnetic head 17 constitutes a magnetic head for a heat-assisted magnetic recording system. Specifically, the magnetic head 17 has a heat assist element that heats the magnetic disk 18 as an assist element to assist magnetic recording. In one example, the heat assist element of the magnetic head 17 includes an LDU 25 mounted on a slider 15, a light-emitting element that irradiates the surface of the magnetic disk with laser light (in this case, a near-field light generating element 63), and a waveguide 66 that propagates the laser light emitted by the LDU 25 to the near-field light generating element 63. Furthermore, the magnetic head 17 has a thermal resistance sensor HRS that detects the surface state (defect state) of the magnetic disk surface, a first thermal actuator that controls the protrusion amount of the write head 58, and a second thermal actuator that controls the protrusion amount of the read head 54.

[0023] The read head 54 has a magnetic film 55 that exhibits a magnetoresistive effect, and shield films 56 and 57 that are positioned to sandwich the magnetic film 55 on the trailing and leading sides of the magnetic film 55. The magnetic film 55 and the shield films 56 and 57 extend almost perpendicularly to the ABS 43. The lower ends of the magnetic film 55 and the shield films 56 and 57 are exposed to the ABS 43 of the slider 15.

[0024] The write head 58 is provided on the trailing end 15b side of the slider 15 relative to the read head 54. The write head 58 has a main magnetic pole 60 that generates a recording magnetic field perpendicular to the surface of the magnetic disk 18, a trailing shield 62 made of a soft magnetic material that is joined to the trailing side of the main magnetic pole 60 and allows magnetic flux to flow through the main magnetic pole 60, a return shield magnetic pole 64 made of a soft magnetic material that is positioned opposite the main magnetic pole 60 with a write gap, a joining portion 67 that physically joins the upper part of the trailing shield 62 to the return shield magnetic pole 64, and a recording coil 70 that is arranged to wrap around the magnetic path including the trailing shield 62 and the return shield magnetic pole 64 in order to allow magnetic flux to flow through the main magnetic pole 60.

[0025] The main magnetic pole 60 is formed of a soft magnetic material having high permeability and high saturation magnetic flux density, and extends almost perpendicularly to the ABS 43. The main magnetic pole 60 has a front surface exposed to the ABS 43 and a magnetic pole end surface that extends upward from the ABS 43, i.e., away from the ABS 43, and faces the near-field light generating element 63.

[0026] The near-field light generator (plasmon generator, near-field transducer) 65 is provided between the main magnetic pole 60 and the return shield magnetic pole 64, and is parallel to and facing the magnetic pole end face of the main magnetic pole 60 with a gap (gap length) between them. The end of the near-field light generator 63 on the ABS 43 side is formed parallel to and flush with the ABS 43. The near-field light generating element 63 is preferably formed of an alloy consisting of Au, Pd, Pt, Rh, or Ir, or several combinations thereof. An insulating layer is interposed between the main magnetic pole 60 and the near-field light generating element 63, and this insulating layer is preferably an oxide consisting of SiO2, Al2O3, etc.

[0027] Waveguide 66 extends from ABS43 to the back of slider 15, i.e., the end face on the suspension side, and is optically connected to LDU25. The end of waveguide 66 on the ABS43 side (extended end) faces the near-field light generating element 63 with a gap between them, almost parallel to each other. An insulating layer is interposed between waveguide 66 and the near-field light generating element 63.

[0028] As described above, the leading surfaces of the main magnetic pole 60, the trailing shield 62, the leading edge of the near-field light generating element 63, and the leading surface of the return shield magnetic pole 64 are exposed to the ABS 43 of the slider 15 and are covered by a protective layer (not shown).

[0029] The first thermal actuator has, for example, a heater 76a as a heating element. The heater 76a is embedded in a protective insulating film 53 and is located near the light head 58. The second thermal actuator has, for example, a heater 76b as a heating element. The heater 76b is embedded in a protective insulating film 53 and is located near the read head 54.

[0030] The thermal resistance sensor HRS is embedded within the protective insulating film 53 and is located between the light head 58 and the read head 54. The detection end (tip) of the thermal resistance sensor HRS is exposed to or slightly protruding from the ABS 43. The thermal resistance sensor HRS is used as an example of an HDI (Head-Disk Interface) sensor.

[0031] Figure 5 is a block diagram that schematically shows the overall configuration of the HDD, including the control system. As shown in Figure 5, the magnetic disk 18, actuator assembly 22, magnetic head 17, and VCM 24 are arranged inside the housing 10. Furthermore, a moisture absorbent M, a humidity sensor HS, and a temperature sensor TS are provided inside the housing 10.

[0032] The HDD includes a controller that includes a head amplifier IC 34 for driving the magnetic head 17, a main controller 47, and a driver IC 48. The head amplifier IC 34 is provided, for example, in the actuator assembly 22 and is electrically connected to the magnetic head 17 via an FPC and a flexi 40. In one example, the head amplifier IC 34 includes a recording current supply circuit (recording current supply unit) 34a that supplies recording current to the recording coil 70 of the magnetic head 17, a heater power supply circuit 34b that supplies drive power to the thermal actuators (first heater 76a and second heater 76b) of the magnetic head 17, a sensor output amplification circuit (not shown) that amplifies the detection signal of the thermal resistance sensor HRS, a read signal amplification circuit 34c that amplifies the signal read by the magnetic head 17, a drive power supply circuit 34d that supplies drive power to a light source, for example, a laser diode unit (LDU) 25, and so on.

[0033] The main controller 47 and driver IC 48 are configured, for example, on a control circuit board 41 located on the rear side of the enclosure 10. The main controller 47 includes a read / write channel (R / W channel) 36, a hard disk controller (HDC) 37, a microprocessor (MPU) 46, memory 44, etc. The main controller 47 is electrically connected to the magnetic head 17 via a head amplifier IC 34. The main controller 47 is electrically connected to the VCM 24 and spindle motor 19 via a driver IC 48. The HDC 37 can be connected to a host computer 49.

[0034] In the main controller 47, the MPU 46 includes a light control unit 46a for controlling the light head, a reed control unit 46b for controlling the reed head, a heater control unit 46c for controlling the power supplied to the thermal actuator, a conversion circuit 46d, a monitoring circuit 46e, a light source control unit 46f for controlling the driving of the light source, and the like. The main controller 47 includes an alarm 48, which is connected to the monitoring circuit 46e. Furthermore, the temperature sensor TS and humidity sensor HS are electrically connected to the main controller 47. The temperature sensor TS and humidity sensor HS each input detection signals to the MPU 46.

[0035] The conversion circuit 46d converts the relative humidity RH inside the housing 10, detected by the humidity sensor HS, into a dew point based on the temperature inside the housing 10 detected by the temperature sensor TS, and sends the converted dew point to the monitoring circuit 46e. An example of the conversion formula is shown below. Saturated water vapor pressure e at a certain temperature T w According to Sonntag's formula,

number

number

number

[0036] The monitoring circuit 46e monitors the dew point sent from the conversion circuit 46d and checks whether it exceeds the predetermined dew point (e.g., 5°C) mentioned above. If it exceeds the predetermined dew point, the monitoring circuit 46e outputs a drive signal to the alarm 48. The alarm 48 emits an alarm, such as an alarm sound or an alarm light, in response to the drive signal. When a drive signal is output from the monitoring circuit 46e, the light source control unit 46f, which is the control unit for the assist element, controls the drive power supply circuit 34d to reduce the assist current supplied to the assist element, in this case the drive current supplied to the LDU25.

[0037] In the HDD configuration described above, during information writing, the main magnetic pole 60 is excited by the recording coil 70, and a recording magnetic field perpendicular to the magnetic recording layer 104 of the magnetic disk 18 directly below is applied from this main magnetic pole 60, thereby recording information on the magnetic recording layer 104 with a desired track width. Furthermore, in heat-assisted magnetic recording, during information writing, laser light is supplied from the LDU 25 to the near-field light generating element 63 through the waveguide 66, and the near-field light generating element 63 generates near-field light. By locally heating the magnetic recording layer 104 of the magnetic disk 18 with the near-field light generated from the near-field light generating element 63, the coercivity of the recording area is reduced. The recording magnetic field from the main magnetic pole 60 is applied to this coercivity-reduced area, and the recording signal is written. In this way, by locally heating the magnetic recording layer 104 and writing the signal to an area where the coercivity has been sufficiently reduced, high-density recording becomes possible.

[0038] On the other hand, when a magnetic disk is locally heated by near-field light, the protective film on the magnetic head may deteriorate, or the lubricant on the magnetic disk may undergo thermal decomposition and chemically react with the material of the light-emitting element. In this case, it is possible that corrosion of the magnetic head and deformation of the light-emitting element may occur due to moisture inside the enclosure. Therefore, it is desirable to control the amount of gaseous moisture inside the enclosure to an amount that does not cause the above-mentioned corrosion or deformation.

[0039] Furthermore, when defining moisture content by relative humidity, the amount of moisture inside the enclosure differs between high-temperature and low-temperature conditions, even at the same relative humidity. Therefore, the actual amount of moisture in the atmosphere is higher at higher temperatures, which accelerates reactions caused by moisture. Therefore, in the HDD according to this embodiment, relative humidity is defined by the dew point, which is the absolute amount of moisture, and the device is configured to maintain the amount of moisture inside the device below a desired value even in a wide temperature range. In other words, as described above, according to this embodiment, the amount of moisture inside the enclosure 10 is defined by the dew point, and the dew point inside the enclosure is set to 5°C or lower.

[0040] Figure 6 shows the relationship between relative humidity (RH), which corresponds to the amount of moisture, and the dew point for ambient temperatures (temperature inside the enclosure) of 30°C and 60°C, respectively. The corrosion state of the magnetic head and the deformation state of the optical elements were investigated under temperature conditions of 25 to 60°C and moisture content of relative humidity of 0.2 to 10% RH. As a result, it was found that corrosion of the magnetic head and deformation of the optical elements can be suppressed by setting the inside of the housing 10 to below the ambient temperature and with a dew point of 5°C or less, at least in the temperature range of -5 to 60°C, and more preferably in the temperature range of 25 to 40°C.

[0041] As mentioned above, the dew point inside the housing 10 can be set to a desired value by adjusting the amount and type of moisture-absorbing material M installed. In one example, the amount of moisture-absorbing material M installed is set to approximately 0.5 to 8% of the internal volume of the enclosure 10. As an example, in a 3.5-inch HDD, we investigated the change in dew point by changing the amount of moisture-absorbing material (zeolite) M installed. We found that by setting the amount of moisture-absorbing material M to approximately 0.1 to 5 g, we were able to maintain the dew point inside the enclosure 10 at 5°C or below.

[0042] As described above, according to the HDD of the first embodiment, the amount of moisture inside the device (HDD) is defined by the dew point, and the dew point inside the device is set to 5°C or lower. This makes it possible to maintain the absolute amount of moisture inside the device in a state where there is no deterioration of the magnetic head and recording medium, or if there is, only minor deterioration, and to maintain the performance of the magnetic recording device at a constant level within a predetermined period. Furthermore, the dew point inside the device is monitored by the controller 47, and if it exceeds the specified dew point, an alarm 48 can be triggered. This allows the operator to take appropriate action in response to the alarm.

[0043] Furthermore, if the dew point inside the device exceeds a specified dew point, the controller is configured to reduce the driving power of the assist element. This suppresses the deterioration of the magnetic head and recording medium caused by moisture inside the device. Based on the above, the first embodiment provides a magnetic recording device that can suppress the deterioration of the head and recording medium and maintain constant performance over a predetermined period of time.

[0044] Next, an example of a manufacturing method for an HDD having the above configuration will be described. In the manufacturing method of HDDs, some or all of the manufacturing processes up to the welding are carried out in a constant temperature chamber with an extremely low humidity environment, such as one with a dew point of 0°C or lower. First, prepare the base 12, inner cover 14, and outer cover 11 of the housing 10. Next, install the spindle motor 19, magnetic disk 18, and lamp 80 on the base 12. Furthermore, install the actuator assembly 22, including the magnetic head 17, and the VCM 24 on the base 12.

[0045] The amount of desiccant needed to maintain a dew point of 5°C or lower inside the enclosure 10 is determined in advance, and the set amount of desiccant M is prepared. Then, the prepared desiccant M is placed inside the base 12.

[0046] Next, the inner cover 14 is screwed to the base 12, closing the upper opening of the base 12. Furthermore, the outer cover 11 is placed on top of the inner cover 14, and the peripheral edge of the outer cover 11 is welded to the base 12 around its entire circumference. This securely fixes the outer cover 11 to the base 12.

[0047] Next, the air inside the housing 10 is exhausted through the ventilation holes 31 and 33 of the inner cover 14 and outer cover 11. Then, a low-density gas (inert gas) with a lower density than air, such as helium (He), is sealed into the housing 10 through these ventilation holes 31 and 33. The low-density gas contains, for example, about 5% oxygen. The oxygen ratio (oxygen concentration) is preferably set to a range of 1% or more and less than 20%. After sealing, a seal 35 is attached to the outer cover 11 to close the ventilation holes 33, thereby sealing the ventilation holes 33.

[0048] Subsequently, a printed circuit board 41 is attached to the bottom surface of the base 12 and electrically connected to the actuator assembly 22 and the spindle motor 19. HDDs (magnetic recording devices) are manufactured through the processes described above.

[0049] Next, the magnetic head of the HDD according to another embodiment will be described. In the other embodiments described below, the same reference numerals are used for parts that are the same as those in the first embodiment described above, and their detailed descriptions are omitted or simplified. The description will focus on the parts that differ from the first embodiment.

[0050] (Second Embodiment) Figure 7 is an enlarged cross-sectional view showing the head portion of the magnetic head in the HDD according to the second embodiment, and Figure 8 is an enlarged cross-sectional view showing the recording head and electric field assist element of the magnetic head. In the HDD according to the second embodiment, the magnetic head has an electric field assist element as an assist element. More specifically, as shown in Figure 7, the head portion 16 of the magnetic head 17 has a read head 54 and a recording head 58 formed by a thin-film process. The read head 54 and the recording head 58 are covered with a protective insulating film 53, except for the portion exposed to the ABS 43 of the slider 15. The head portion 16 may also include a first heater 76a for heating the recording head 58 and a second heater 76b for heating the read head 54.

[0051] The recording head 58 includes a main magnetic pole 60 that generates a recording magnetic field perpendicular to the surface of the magnetic disk 18, a trailing shield (light shield magnetic pole) 62 that faces the main magnetic pole 60 with a light gap WG placed between them, a return shield magnetic pole 64 that faces the reading side of the main magnetic pole 60, a first recording coil 70 wound between the main magnetic pole 60 and the trailing shield 62, and a second recording coil 72 wound between the main magnetic pole 60 and the return shield magnetic pole 64.

[0052] The trailing shield 62 has a first connection portion 50 connected to the main magnetic pole 60. The first connection portion 50 is magnetically connected to the upper part of the main magnetic pole 60 via a non-conductive material 52. The return shield magnetic pole 64 has a second connection portion 68 joined to the main magnetic pole 60 at a position spaced apart from the ABS 43. This second connection portion 68 is formed of, for example, a soft magnetic material and is magnetically connected to the upper part of the main magnetic pole 60 via a non-conductive material 59.

[0053] The recording head 58 is equipped with a high-frequency oscillator, such as a spin-torque oscillator (STO) 65, which functions as an electric field assist element. As shown in Figure 8, the STO65 is provided between the main magnetic pole 60 and the trailing shield 62 within the light gap WG. In one example, the STO65 has a spin injection layer 65a, an intermediate layer (non-magnetic conductive layer) 65b, and an oscillation layer 65c, and these layers are stacked sequentially from the main magnetic pole 60 side to the trailing shield 62 side. The spin injection layer 65a is bonded to the main magnetic pole 60 via a non-magnetic conductive layer (underlayment layer) 67a. The oscillation layer 65c is bonded to the trailing shield 62 via a non-magnetic conductive layer (cap layer) 67b. Note that the stacking order of the spin injection layer 65a, intermediate layer 65b, and oscillation layer 65c may be reversed from the above, that is, they may be stacked sequentially from the trailing shield 62 side to the main magnetic pole 60 side.

[0054] As shown in Figure 7, the main magnetic pole 60 and trailing shield 62 are connected to connection terminal 45 via wiring, and further connected to the head amplifier IC 34 and main controller 47 via a flexi-shape. A current circuit is configured to supply the STO drive current (bias voltage) in series from the head amplifier IC through the main magnetic pole 60, STO 65, and trailing shield 62. The first recording coil 70, the second recording coil 72, the first heater 76a, and the second heater 76b are connected to connection terminal 45 via wiring, and further connected to the head amplifier IC 34 via a flexi-shape 40. The HDD according to the second embodiment includes the head amplifier IC 34 and main controller 47 shown in Figure 5. However, when using an electric field assist element (STO65), the drive power supply circuit 34d of the head amplifier IC 34 shown in Figure 5 constitutes a drive power supply circuit that supplies drive current to the STO65. In addition, the light source control unit 46f of the MPU 46 constitutes a drive control unit that controls the driving of the STO65.

[0055] In the second embodiment, the configuration of the HDD, excluding the magnetic head, is the same as that of the HDD according to the first embodiment. That is, similar to the first embodiment, the inside of the housing of the HDD according to the second embodiment is set to be below the ambient temperature and have a dew point of 5°C or less in the temperature range of at least 25 to 40°C. Furthermore, it is preferable that the dew point inside the housing is below the ambient temperature and 5°C or less in the temperature range of at least -5 to 60°C.

[0056] With the HDD configured as described above, when writing information, the drive power supply circuit 34d of the head amplifier IC 34 applies a bias voltage to the main magnetic pole 60 and trailing shield 62 under the control of the MPU 46, thereby supplying a drive current in series through the connection terminal 45, wiring, main magnetic pole 60, STO 65, and trailing shield 62. The drive current flows in a direction perpendicular to the stacking surface of the STO 65. The STO 65 oscillates a spin torque, applying a high-frequency magnetic field to the magnetic recording layer 104 of the magnetic disk 18.

[0057] Simultaneously, the recording current supply circuit 34a of the head amplifier IC 34 supplies recording current to the first and second recording coils 70 and 72 according to the recording signal and recording pattern generated from the R / W channel 36. The first and second recording coils 70 and 72 excite the main magnetic pole 60 to generate a recording magnetic field, and apply a recording magnetic field perpendicular to the magnetic recording layer 104 directly below the main magnetic pole 60. This records information on the magnetic recording layer 104 with the desired track width. By superimposing the high-frequency magnetic field of STO 65 on the recording magnetic field, the magnetization reversal of the magnetic recording layer 104 is promoted, enabling magnetic recording with high magnetic anisotropy energy.

[0058] In the HDD according to the second embodiment configured as described above, the same effects and advantages as those of the HDD according to the first embodiment can be obtained. That is, by setting the dew point inside the housing to 5°C or lower, it is possible to suppress the deterioration of the head and recording medium and provide a magnetic recording device that can maintain constant performance over a predetermined period of time.

[0059] The present invention is not limited to the embodiments described above, and in the implementation stage, the components can be modified and implemented without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. For example, the assist element of the magnetic head is not limited to a thermal assist element or an electric field assist element; other assist elements may be used. It is also possible to apply a magnetic head without an assist element. Furthermore, the type of moisture absorbent is not limited to the embodiments described above; other moisture absorbents can be selected. [Explanation of symbols]

[0060] 10...Housing, 12...Base, 12a...Bottom wall, 12b...Side wall, 17...Magnetic head 18...Magnetic disk, 19...Spindle motor, 22...Actuator assembly, 25... Laser oscillator, 30... Suspension assembly, 34...Head amplifier IC, 46...MPU, 47...Controller, 58...Recording head 60...Main magnetic pole, 63...Near-field light generating element, 65...High-frequency oscillator, M...Moisture-absorbing material

Claims

1. A housing with an internal dew point of 5°C or lower, A disk-shaped recording medium provided inside the aforementioned housing, A magnetic head provided inside the housing performs information processing on the recording medium, A magnetic recording device equipped with the following features.

2. The magnetic recording apparatus according to claim 1, wherein, in a temperature range of at least -5 to 60°C, the dew point inside the housing is below the ambient temperature and 5°C or less.

3. The magnetic recording apparatus according to claim 1, further comprising a moisture-absorbing material provided inside the housing.

4. The magnetic recording apparatus according to claim 1, wherein the magnetic head includes a heat assist element.

5. The magnetic recording apparatus according to claim 4, wherein the heat assist element includes a laser light source and an optical element that irradiates the recording medium with laser light.

6. The magnetic recording apparatus according to claim 1, wherein the magnetic head includes an electric field assist element.

7. The magnetic recording apparatus according to claim 1, wherein the inside of the housing contains 1% or more and less than 20% oxygen.

8. A humidity sensor is provided inside the aforementioned housing, The magnetic recording apparatus according to claim 1, further comprising a controller including a conversion circuit for converting relative humidity measured by the humidity sensor into a dew point.

9. The magnetic recording device according to claim 8, wherein the controller includes a monitoring circuit for monitoring the dew point and an alarm that outputs an alarm when the dew point exceeds 5°C.

10. The magnetic head includes an assist element that assists magnetic recording. The magnetic recording apparatus according to claim 9, wherein the controller includes a drive power supply circuit that supplies a drive current to the assist element, and a drive control unit that reduces the drive current when the alarm is output.

11. A method for manufacturing a magnetic recording device, Prepare a quantity of desiccant to maintain the dew point inside the magnetic recording device housing at 5°C or below. In a constant temperature chamber with a dew point below 0°C and low humidity, A spindle motor, a disk-shaped recording medium, an actuator assembly including a magnetic head, a voice coil motor, and the moisture-absorbing material are installed on the base of the housing. The cover is fixed to the base to form the housing. A method for manufacturing a magnetic recording device.

12. A method for manufacturing a magnetic recording apparatus according to claim 11, wherein a low-density gas having a lower density than air and an oxygen concentration of 1% or more and less than 20% is sealed inside the housing.

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