JP2008052882A - Magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a projection amount of a medium facing surface under a high-temperature and worst environment in which write electric power is large, even in a structure of high heater efficiency in which the medium facing surface is largely projected with low electric power. <P>SOLUTION: A magnetic head 18 has a read head 36 in which a read element 46 which converts recording magnetic flux emitted from a magnetic disk 14 into an electric signal is disposed between a pair of shield layers 42, 44 on a substrate 34, and magnetically records information by emitting magnetic flux generated by a write current flowing through a write coil 54 from a magnetic pole unit 48 to the magnetic disk 14. A heater coil 60 is disposed to face the write coil 54 via an insulating layer, and a medium facing surface 40 is caused to protrude toward the recording medium side by thermal expansion caused by electric power distribution and heating. Subsequent to the shield layer in the substrate side, a low thermal conducting layer 62 made of a material having a low thermal conductivity which suppresses transmission of the heat caused by electric power distribution to and heating of the heater coil 60 and a low thermal expansion layer 64 which is disposed in the substrate 34 side of the low thermal conducting layer 62 and is made of a material having a low thermal expansion coefficient are disposed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a magnetic head that can control a clearance between a head and a recording medium by changing a protrusion amount of a medium relative surface by thermal expansion accompanying energization heating of a heater coil, and in particular, with a small heater coil power. The present invention relates to a magnetic head capable of obtaining a large amount of protrusion of a medium relative surface.

  Conventionally, it is necessary to reduce the flying height of the magnetic head with respect to the recording surface of the magnetic disk in order to realize a high recording density of the magnetic disk device, and in recent years, a flying height of the order of 10 nm has been realized.

  However, if the flying height of the magnetic head decreases, collisions with small protrusions on the magnetic disk surface are likely to occur, and clearance variations between heads exist within the mechanical tolerance range. Cannot be set lower than the tolerance range.

  As a method for solving this problem, Patent Document 1 in which a heater is incorporated in the head and the clearance between the head and the recording surface of the magnetic disk is controlled by utilizing a protrusion phenomenon due to thermal expansion of the head flying surface accompanying energization of the heater. ~ 3 have been proposed.

  In Patent Document 1, a thin film resistor that functions as a heater is formed in an insulator layer of a thin film magnetic head, and the thin film resistor is energized to generate heat as necessary, thereby thermally expanding the tip of the magnetic pole. It is made to protrude.

  In Patent Document 2, the device temperature and the recording / reproduction increase the device temperature, and the power applied to the electric conductive film provided on the head is changed to keep the device temperature constant. To keep the clearance.

Patent Document 3 discloses a heating apparatus for increasing the flying height that expands and projects a part of the air bearing surface of the head by heating to increase the distance between the recording / reproducing element and the magnetic disk surface, and other head air bearing surfaces by heating. A flying height reduction heating device that reduces the distance between the read / write element and the magnetic disk surface by expanding and projecting part of the head is provided on the head, and the flying height is corrected so that playback can be performed without causing a collision when the device is started. is doing.
JP 2003-303405 A JP 2004-192665 A Japanese Patent Laying-Open No. 2005-078706 JP-A-5-20635 JP 2005-071546 A JP 2005-276284 A

  In a conventional magnetic head incorporating such a heater, the heat generated by energizing the heater coil propagates to the substrate side of the magnetic head configured as a slider and escapes to the medium-facing surface, and the write head recording There is a problem that the medium relative surface side where the write gap functioning as an element and the read gap where the reading element of the read head is located cannot be efficiently overheated and protruded.

  For this reason, the power supplied to the heater coil is increased to increase the amount of protrusion due to thermal expansion. However, if the heater coil becomes too hot, the influence of the heater coil migration and the heat on the read element and write element will increase. Thus, there is a problem in that the durability and performance of the magnetic head deteriorates.

  In order to solve such a problem, it is conceivable to provide the head with a structure that prevents the heat generated by energizing the heater coil from escaping. However, if the heat generated by the heater coil becomes difficult to escape, even if the heater coil is not energized, if the write power increases in a high temperature environment, the medium relative surface will protrude due to the ambient temperature and the heat generated by the light coil, and the substrate side However, since the structure is such that heat does not easily escape, there is a problem that the amount of protrusion due to the ambient temperature and the heat generation of the light coil is further increased.

Usually, the design value of the clearance with respect to the medium surface of the magnetic head is such that when the upper limit temperature of the usable temperature range of the magnetic disk device is 60 ° C., the temperature inside the housing is about 70 ° C., which is higher than that. Set the worst condition under which AC current was passed through the light coil in a high temperature environment and measure the protrusion amount of the head. Based on the protrusion amount under the worst condition, set the clearance design value so as not to cause contact collision with the medium. I have decided.

  However, if a structure that prevents the heat from the heater coil from escaping is used for the head, the amount of protrusion of the head under the worst condition will increase, and therefore the clearance design value to avoid contact collision with the medium will be increased. There must be. Thus, when the design value of the clearance is increased, the amount of protrusion due to energization of the heater must be further increased.To this end, it is necessary to increase the heater power. There is a problem that it is difficult to improve.

  Further, in recent years, a magnetic disk device using a contact type magnetic head that accesses a conventional floating type head while the head is in contact with the medium surface has been proposed. With respect to such a contact type magnetic head, heater control that maintains contact with the medium surface by arranging a heater coil in the head and overheating the current and projecting the medium contact surface by thermal expansion can be considered.

  In the contact control by the heater coil of such a contact type magnetic head, the clearance between the head and the medium becomes an atomic level world. In such a situation, the atoms on the head side and the atoms on the medium side They are attracted by the interatomic force generated by this interaction, that is, the Coulomb force.

  Therefore, in a contact type magnetic head, it is necessary to maintain a contact state so as to maintain a balance with the Coulomb force between the head and the medium by a head actuator. However, when the amount of protrusion is controlled by energization of the heater coil in the world where the Coulomb force is applied, the medium-relative surface of the head protrudes entirely toward the medium centering on the portion of the write coil that is overheated by the heater coil. For this reason, there is a problem that the relative area of the head side where the Coulomb force is generated with the medium increases, the Coulomb force increases, the balance of the head actuator is lost, and the head is pressed against the medium surface with a strong force.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic head having a structure with high heater efficiency capable of projecting a medium relative surface with a small amount of electric power with respect to a heater coil.

  In addition, the present invention can secure the heater efficiency by reducing the clearance at the time of designing by reducing the amount of protrusion of the medium relative surface in the worst environment where the write power is high and the power environment is high even if the heater efficiency is high. It is an object of the present invention to provide a magnetic head having a structure.

It is another object of the present invention to provide a magnetic head capable of appropriately controlling the protrusion of the medium relative surface by energizing a heater coil in a contact head in which the Coulomb force is a problem.

The present invention provides a read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a magnetic flux generated by a write current flowing in a write coil as a magnetic pole. In a magnetic head sequentially arranged with a write head for magnetically recording information by discharging toward the recording medium from the section,
A heater coil that is disposed through an insulating layer with respect to the write coil, and that causes the medium relative surface to protrude toward the recording medium side by thermal expansion by energization overheating;
A low thermal conductive layer made of a material having a low thermal conductivity, which is arranged subsequent to the shield layer on the substrate side in the read head, and suppresses the propagation of heat due to overheating of the heater coil;
A low thermal expansion layer disposed on the substrate side of the low thermal conductive layer and made of a material having a low coefficient of thermal expansion;
It is provided with.

Here, the low thermal conductive layer is made of silicon oxide (SiO ₂ ) or a resin material. The low thermal expansion layer is any one of silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), aluminum nitride (AlN), tungsten (W), molybdenum (M), or Invar material. Comprising one.

The low thermal expansion layer has a thermal expansion coefficient of 0.0 / K to 7.5E-6 / K (= 0.0 / K to 7.5 × 10 ⁻⁶ / K). The low thermal conductive layer has a thermal conductivity of 0.1 W / m to 1.5 W / m.

Another embodiment of the present invention is generated by a read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a write current flowing in a write coil. A magnetic head in which a write head for magnetically recording information by releasing the magnetic flux from the magnetic pole part toward the recording medium is sequentially arranged.
A heater coil that is disposed relative to the write coil via an insulating layer, and that causes the medium relative surface to protrude toward the recording medium by thermal expansion due to energization overheating;
A low thermal conductive layer made of a material having a low thermal conductivity, which is arranged subsequent to the shield layer on the substrate side in the read head, and suppresses the propagation of heat due to overheating of the heater coil;
It is provided with.

Here, the low thermal conductive layer is made of silicon oxide (SiO ₂ ) or a resin material. The low thermal conductive layer has a thermal conductivity of 0.1 W / m to 1.5 W / m.

Another embodiment of the present invention is generated by a read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a write current flowing in a write coil. A magnetic head in which a write head for magnetically recording information by releasing the magnetic flux from the magnetic pole part toward the recording medium is sequentially arranged.
A heater coil that is disposed through an insulating layer with respect to the write coil, and that causes the medium relative surface to protrude toward the recording medium side by thermal expansion by energization overheating;
A low Young's modulus layer made of a material having a low Young's modulus, which is arranged following the shield layer on the substrate side in the read head and is easily deformable against thermal expansion;
It is provided with.

  Furthermore, a low thermal expansion layer made of a material having a low coefficient of thermal expansion may be provided on the substrate side of the low Young layer.

  Here, the low Young's modulus layer comprises any of resist, polyimide, or amorphous fluororesin. The low Young's modulus layer has a Young's modulus of 1 GPa to 50 GPa.

  The low Young's modulus layer locally protrudes the medium relative surface including the reading element and the recording element with respect to the substrate side due to overheating of the heater coil.

The low Young's modulus layer keeps the contact state with the medium by locally projecting the medium relative surface including the reading element and the recording element with respect to the substrate side due to overheating of the heater coil.

  According to the present invention, a low thermal conductive layer made of a material having low thermal conductivity is arranged in a path through which heat due to energization overheating of the heater coil propagates to the substrate side, so that heat due to energization overheating of the heater coil is recorded on the recording element. (Write gap) and the reading element (read gap) can be encapsulated on the medium facing surface side to sufficiently heat the write coil, and the heater efficiency can be improved by projecting with a small heater power.

  At the same time, a low thermal expansion layer made of a material with a low coefficient of thermal expansion is arranged on the substrate side following the low thermal conductivity layer, so that the heat transmitted by the energization of the heater coil can be suppressed by the low thermal conductivity layer and at the same time Since the thermal expansion coefficient is low, the low thermal expansion layer functions as a fixed portion with little deformation against thermal expansion. Due to the presence of this fixed portion, there is a recording element (write gap) and a reading element (read gap). The protruding amount of the relative surface can be suppressed.

  For this reason, the amount of protrusion of the medium relative surface under the worst condition that results in high write power in a high-temperature environment can be suppressed, and the amount of protrusion under the worst condition is suppressed, thereby providing a low heat conduction layer to increase heater efficiency. Even with this structure, it is not necessary to increase the design value of the clearance set to avoid the collision with the medium surface, and the medium relative surface can be projected with good heater efficiency without increasing the heater power.

  In another embodiment of the present invention, the main objective is to improve the heater efficiency, and a low thermal conductive layer made of a material having low thermal conductivity is provided in a path through which heat generated by energization overheating of the heater coil propagates to the substrate side. By arranging it, the heat due to energization overheating of the heater coil can be sealed and mixed on the medium facing surface side where the recording element (write gap) and reading element (read gap) are present, and the write coil can be heated sufficiently. Further, the heater efficiency can be improved by greatly projecting the medium relative surface with a small heater power.

Furthermore, in another embodiment of the present invention, a low Young's modulus layer made of a material having a low Young's modulus that is easily deformable against thermal expansion is disposed after the shield layer on the substrate side in the read head, The recording element and the reading element projecting due to thermal expansion due to energization overheating of the heater coil are arranged via a soft low Young's modulus layer that is easily deformed with respect to the substrate side, which is the fixed side. The medium relative surface side where the recording and reading elements exist is locally projected from the rate layer, minimizing the area of the medium relative surface between the medium side and reducing the increase in Coulomb force due to the protrusion. The amount of protrusion can be controlled appropriately without breaking the balance of the head actuator that is in contact.

  FIG. 1 is an explanatory diagram of a magnetic disk apparatus in which the magnetic head of the present invention is used. In FIG. 1, the magnetic disk device 10 shows the internal structure of the housing base 12 with the housing cover removed. A magnetic disk 14 that is rotated at a constant speed by a spindle motor is provided in the housing base 12, and a rotary actuator 16 is rotatably disposed on the magnetic disk 14 by a shaft portion 15.

  The rotary actuator 16 supports the magnetic head according to the present invention at the tip, and the coil 22 is disposed at the rear. The coil 22 can be rotated along a magnet 26 on a lower yoke 24 fixed to the housing base 12 side, and an upper yoke having the same shape as the lower yoke 24 (not shown) is disposed on the coil 22. In this embodiment, the upper yoke is removed.

  A magnetic circuit part is formed by the lower yoke 24, the magnet 26 and the upper yoke (not shown), and the coil 22 is arranged in the magnetic circuit part, thereby constituting a voice coil motor for driving the rotary actuator 16. ing. The rotary actuator 16 is in a latched state by retracting the magnetic head 18 from the magnetic disk 14 to the ramp load mechanism 20 in the illustrated state.

  FIG. 2 is a cross-sectional view showing an embodiment of a magnetic head according to the present invention. In FIG. 2, the magnetic head 18 of this embodiment is provided on the leading end side of the slider, and a read head 36 and a write head 38 are sequentially arranged following the substrate 34.

  The magnetic head 18 has a medium relative surface 40 facing the medium surface of the magnetic disk 14, and the medium relative surface 40 is a part of an air bearing that floats in response to an air flow caused by the movement in the disk rotation direction 32 indicated by the arrow of the magnetic disk 14. Part.

The read head 36 provided on the substrate 34 side is formed between shield layers 42 and 44 by forming shield layers 42 and 44 in an insulating layer 45 using aluminum oxide Al ₂ O ₃ known as alumina. A read element 46 is disposed at a position corresponding to a read gap on the medium facing surface 40, and a GMR element (Giant Magneto Resistance) or a TMR element (Tunneling Magneto Resistance) is used as the read element 46.

  Following the read head 36, a write head 38 is provided. The write head 38 has a magnetic pole portion 48, and the magnetic pole portion 48 includes an inner magnetic pole 50 on the read head 36 side and an outer magnetic pole 52 on the tip side. As the magnetic pole portion 48, a magnetic material such as permalloy or iron cobalt alloy is used.

  The outer magnetic pole 52 is located on the medium relative surface 40 side and protrudes forward, and a write gap 56 is formed between the medium magnetic surface 40 and the inner magnetic pole 50. A coil passing portion is formed below the connecting portion between the inner magnetic pole 50 and the outer magnetic pole 52, and the light coil 54 is arranged in a spiral shape with the connecting portion between the inner magnetic pole 50 and the outer magnetic pole 52 as the center.

  The write coil 54 of this embodiment has a double winding structure. The write coil 54 generates a recording magnetic flux by flowing a write current, and this magnetic flux is emitted from the write gap 56 of the magnetic pole portion 48 toward the magnetic disk 14 to record magnetic information on the magnetic disk 14. .

  Further, in the magnetic head 18 of the present embodiment, the heater coil 60 is disposed on the inner magnetic pole 50 side as viewed from the write coil 54 in the write head 38. The heater coil is made of a high resistance heating material such as tungsten (W) or titanium tungsten (TiW).

  When the heater coil 60 is energized to generate heat, the heat is transmitted to the opposing write coil 54 via the insulating layer 45, and the write coil 54 is thermally expanded, so that the read element 46 and the write element of the medium facing surface 40 are used. A portion including the functioning write gap 56 is projected to the magnetic disk 14 side.

  In addition to the basic shape of the magnetic head 18, in the present embodiment, the low thermal conductive layer 62 is disposed after the shield layer 42 in the read head 36, and further, the low thermal expansion layer 64 is followed by the low thermal conductive layer 62. Is arranged.

  The low thermal conductive layer 62 conducts heat toward the medium facing surface 40 after the heat generated by the energization heating of the heater coil 60 is propagated to the substrate 34 side, and dissipates the heat, so that the heat propagation path from the heater coil 60 is blocked. Thus, it arrange | positions behind the shield layer 42, and suppresses the propagation of the heat | fever to the board | substrate 34 side.

As a material for forming the low thermal conductive layer 62 that suppresses the propagation of heat in this way, a material having a low coefficient of thermal expansion, such as silicon oxide SiO ₂ or a resin material, is used. The low thermal conductive layer 62 of the present embodiment has a thermal conductivity of 0.1 W / m to 1.5 W / m.

The low thermal expansion layer 64 formed subsequent to the low thermal conductive layer 62 includes any one of silicon carbide SiC, silicon nitride Si ₃ N ₄ , silicon oxide SiO ₂ , aluminum nitride AlN, or Invar material. In the present embodiment, the thermal expansion coefficient of the low thermal expansion layer 64 is 0.0 / K to 7.5E-6 / K (= 0.0 / K to 7.5 × 10 ⁻⁶ / K).

  Even if the low thermal expansion layer 64 is heated by the propagation of heat from the heater coil 60, the low thermal expansion coefficient has a low thermal expansion coefficient. Therefore, the low thermal expansion layer 64 functions as a fixed layer from the viewpoint of the thermal expansion coefficient. Positioning the functioning low thermal expansion layer 64 serves to suppress the protrusion of the medium relative surface 40 due to the thermal expansion of the portion having a high thermal expansion coefficient on the tip side including the read head 36 and the write head 38.

  That is, the low thermal conductive layer 62 suppresses the propagation of heat to the substrate 34 side due to the heating energization of the heater coil 60 and confines heat to the light coil 54 side that determines the amount of protrusion of the medium relative surface 40, thereby reducing the heater coil. The amount of protrusion can be increased with the amount of electric power of 60, and the heater efficiency is increased.

  On the other hand, the low thermal expansion layer 64 acts as a fixing portion because it has little thermal expansion when receiving heat from the heater coil 60, and the medium relative surface 40 on the read head 36 and write head 38 side protrudes. Therefore, the low thermal expansion layer 64 acts to reduce the heater efficiency.

  However, the low thermal expansion layer 64 serves to suppress the protrusion of the medium relative surface 40 due to heat generation when the power of the write coil 54 is high at a high temperature, thereby avoiding the collision of the magnetic head 18 due to the unevenness of the magnetic disk 14. Therefore, it acts to minimize the design value of the clearance.

That is, in the design stage of the magnetic head 18, the upper limit temperature of the operating temperature range of the magnetic disk device, for example, 60 ° C., the temperature of the magnetic head 18 in the housing is 70 ° C., which is 10 ° C. higher than that. A worst-case condition for passing an AC current to the write coil 54 in this high temperature state is set, and the clearance design value is set such that the clearance with the magnetic disk 14 does not cause a collision from the amount of protrusion of the medium relative surface 40 under this worst-case condition. Have decided.

  However, in the present embodiment, the low thermal conductive layer 62 is arranged so that the heater efficiency on the read head 36 and write head 38 side, that is, the degree of protrusion with respect to heat, increases, and the worst condition that the recording power is maximized at a high temperature. When set, the medium relative surface 40 on the side of the read head 36 and the write head 38 protrudes greatly by suppressing the diffusion of heat by the low thermal conductive layer 62.

  For this reason, it is necessary to take a large design value of the clearance in consideration of an increase in the protruding amount of the medium relative surface 40 in the worst condition. However, when the clearance design value is increased, the amount of protrusion when the medium relative surface 40 is protruded by energization heating of the heater coil 60 in a normal use state must be increased as the clearance design value increases.

  As a result, the amount of electric power flowing to the heater coil 60 is increased and the magnetic head 18 is locally heated to a high temperature, and the write gap functions as a migration element of the heater coil 60 or a read element 46 of the read head 36 or a write element in the write head 38. 56 is adversely affected.

  Therefore, in the present embodiment, the low thermal expansion layer 64 is disposed after the low thermal conductive layer 62 to reduce the thermal expansion coefficient, and the amount of protrusion of the medium relative surface 40 under the worst condition where the recording temperature is high and the recording power is large. By suppressing the presence of the low thermal expansion layer 64, it is possible to avoid increasing the clearance design value, and as a result, the heater efficiency can be increased.

  In the present embodiment, the low thermal conductive layer 62 has a thickness of 0.5 μm to 4.0 μm, for example, and the low thermal expansion layer 64 has a thickness of 0.5 μm to 4.0 μm, for example.

  FIG. 3 is an explanatory diagram of a protruding state due to thermal expansion when the heater coil 60 is energized. In FIG. 3, when the heater coil 60 is energized, the heat generated by the heater coil 60 is transmitted to the write coil 54, and the write coil 54 is heated and expanded.

  Further, the heat transmitted from the heater coil 60 to the substrate 34 side through the shield layers 44 and 42 is suppressed by the low heat conductive layer 62, and the heat generated by the heater coil 60 is on the tip side as viewed from the low heat conductive layer 62. Contained in the head area.

  As a result, the medium facing surface 40 of the magnetic head 18 forms a protruding portion 66 that protrudes toward the magnetic disk 14 centering on the write gap position 70 facing the write coil 54, and the read gap position 68 where the read element 46 is disposed is also the same. The clearance between the write gap 56 and the read element 46 with respect to the magnetic disk 14 can be controlled by the protrusion amount of the protrusion 66.

  FIG. 4 is a perspective view showing the internal structure of the magnetic head 18 of the present embodiment, excluding the insulating layer. In FIG. 4, an inner magnetic pole 50 constituting a magnetic pole portion of the write head 38 is disposed on the front side of the substrate 34 via a read head 36 composed of two shield layers 42 and 44, and forward from the inner magnetic pole 50. An outer magnetic pole 52 is disposed on the protruding portion.

  The outer magnetic pole 52 has a tip 55 formed on the medium-facing surface with respect to the magnetic disk, and the width of the tip 55 determines the recording width of the magnetic disk. A write coil 54 is formed between the outer magnetic pole 52 and the inner magnetic pole 50 in a spiral manner with a double winding. That is, the write coil 54 is pulled in from the upper right side of the front, wound in a spiral shape by the outer magnetic pole 52, bent toward the substrate 34 at the center and unwound in the same direction, and then taken out to the right side. Yes.

  In addition to such a basic shape of the magnetic head 18, a low thermal conductive layer 62 is disposed subsequent to the shield layer 42 on the substrate side of the read head 36, so that heat is propagated to the substrate 34 side by energization heating of the heater coil 60. Suppressed.

  A low thermal expansion layer 64 is provided subsequent to the low thermal conductive layer 62. The low thermal expansion layer 64 functions as a fixed side due to low thermal expansion, and has a high temperature and a maximum recording power. The protrusion of the medium relative surface is suppressed.

  FIG. 5 is a cross-sectional view of FIG. 4 cut at the center position. As is apparent from the cross-sectional view of FIG. 5, it can be seen that the write coil 54 is disposed in a spiral manner around the connecting portion connecting the outer magnetic pole 52 and the inner magnetic pole 50. A write gap 56 is formed inside the tip 55 of the outer magnetic pole 52. Further, a read element 46 is disposed between the shield layers 42 and 44 on the substrate 34 side, thereby constituting a read head 36.

  Further, a low thermal conductive layer 62 and a low thermal expansion layer 64 are laminated on the substrate 34 side with respect to the basic shape of the magnetic head 18 including the read head 36 and the write head 38.

  FIG. 6 is an explanatory view showing the internal structure excluding the write coil 54 of FIG. Except for the write coil 54, a heater coil 60 is disposed behind the write coil 54. The heater coil 60 forms a coil pattern having a constant width at a position opposite to the write coil 54 shown in FIG. 4, and a wide terminal pattern is connected to and pulled out from both ends of the coil pattern.

  FIG. 7 is a cross-sectional view showing another embodiment of the magnetic head according to the present embodiment in which only the low thermal conductive layer is arranged with respect to the basic shape of the magnetic head. In the embodiment of FIG. 7, the configuration of the read head 36 and the write head 38 disposed on the front end side of the substrate 34 is the same as that of the embodiment of FIG. 2, and similarly the heater on the substrate 34 side of the write coil 54. A coil 60 is arranged so that the medium facing surface 40 can protrude toward the magnetic disk 14 by energization heating of the heater coil 60.

  Subsequent to the shield layer 42 on the substrate 34 side of the read head 36, only the low thermal conductive layer 62 is disposed. For this reason, the embodiment of FIG. 7 in which only the low thermal conductive layer 62 is arranged with respect to the basic shape is an embodiment intended to improve the heater efficiency mainly by increasing the amount of protrusion of the medium relative surface 40 with a small energization amount of the heater coil 60. It can be said.

  FIG. 8 is a sectional view showing, as a comparative example, a magnetic head having a basic shape that does not have a low thermal conductive layer and a low thermal expansion layer. In the magnetic head 18-2 of FIG. 8 shown as a comparative example, a read head 36 and a write head 38 are provided following the substrate 34, and this structure is the same as that of the embodiment of FIG.

  FIG. 9 is an explanatory diagram showing the measurement result of the protruding position of the present embodiment in the high-temperature energized state, which is the worst condition, in comparison with the comparative example. The high temperature energized state in FIG. 9 means that when the operating temperature range of the magnetic disk device is 0 ° C. to 60 ° C., for example, the temperature of the magnetic head is 10 ° C. to 70 ° C. which is higher by about 10 ° C. The measurement result of the protruding position when the heater coil is not energized, with the maximum environmental temperature of 70 ° C. and the AC current giving the maximum power as the recording current to be passed through the write coil.

  In FIG. 9, the horizontal axis indicates the position of the medium relative surface 40 of the magnetic head, where the read gap position 68 is 0 μm, the tip side where the write gap position 70 of the write head is located is positive, and the substrate side is negative. . The vertical axis represents the protruding position, and shows the protruding position in the high-temperature energized state with the position of the medium relative surface in the room temperature state being 0 nm.

  First, the protrusion position profile 72 is a case of the embodiment in which the low thermal conductive layer 62 and the low thermal expansion layer 64 shown in FIG. 2 are arranged. In the negative position on the substrate side, the protrusion amount is as small as 1 nm or less. However, as the read gap position 68 is approached, the amount of protrusion sharply increases, and the peak protrusion amount increases to around 4.0 nm before the write gap position 70, and then protrudes toward the head tip side, which is the plus side. The position is lowered, and a protrusion amount of about 3.5 nm is obtained at the write gap position 70.

  Moreover, the protrusion position profile 74 shown with a dashed-dotted line is a case of embodiment in which only the low thermal conductive layer 62 shown in FIG. 7 is provided and the low thermal expansion layer is not provided. In this case, by providing the low thermal conductive layer 62, the diffusion of heat to the substrate side is suppressed and confined to the tip side. As a result, the peak protrusion amount increases to 4.6 nm, and the heater coil is energized. Although not done, the ratio of the amount of protrusion to heat is large.

  On the other hand, the protruding position profile 76 shown by a dotted line is a comparative example of only the basic shape without the low thermal conductive layer and the low thermal expansion layer of FIG. 8, and the protruding position profile 72 of the embodiment in which the low thermal conductive layer and the low thermal expansion layer are provided. And the protrusion position profile 74 of only the low heat conduction layer.

  From the comparison with the protruding position profile 76 as a comparative example, it can be seen that when the low thermal conductive layer is provided, the degree of the protruding amount with respect to heat is increased as in the protruding position profile 74. Moreover, about embodiment of the protrusion position profile 72 which added the low thermal expansion layer in addition to the low thermal conductive layer, it turns out that the protrusion amount is suppressed as a whole by providing the low thermal expansion layer.

  For this reason, according to the protrusion position profile 72 of the embodiment in which both the low thermal conductive layer and the low thermal expansion layer in FIG. 2 are provided, the protrusion amount of the medium-relative surface of the head in the worst condition in which the high temperature energization state is achieved The protrusion position profile 74 of the embodiment and the protrusion position profile 76 as a comparative example are suppressed to a lower value, and thereby the clearance design value can be minimized when determining the clearance design value under the worst condition.

  FIG. 10 is an explanatory view showing the protruding position of this embodiment in comparison with the comparative example in the case where the heater coil is energized at 100 mW in the high temperature energized state of FIG. In FIG. 10, the protruding position profile 78 indicated by a solid line is a case where both the low thermal conductive layer and the low thermal expansion layer of FIG. 2 are provided, and the protruding position profile 80 is a case where only the low thermal conductive layer of FIG. Furthermore, a broken protrusion position profile 82 is a comparative example of FIG.

  With respect to the protruding position when the heater is energized, both the protruding position profile 78 of the embodiment of FIG. 2 and the protruding position profile 80 of the embodiment of FIG. 7 can conduct heat to the substrate side by disposing the low thermal conductive layer. Thus, a protrusion amount of about 17 nm is secured at the read gap position 68 and a protrusion amount of 22 nm substantially corresponding to the peak value is secured at the write gap position 70.

  On the other hand, in the protruding position profile 82 according to the comparative example having only the basic shape without the low thermal conductive layer and the low thermal expansion layer, the lead gap position 68 is about 18 nm, and the write gap position 70 is about 17.5 nm. For the example protrusion position profile 82, both the embodiment of FIG. 2 and the embodiment of FIG. 7 obtain a sufficiently large head protrusion amount for the same heater energization amount.

  FIG. 11 is an explanatory diagram of an embodiment in which a piezoelectric sensor structure using aluminum nitride AlN is disposed in the low thermal expansion layer in the embodiment of FIG. 2 and used as a collision sensor. FIG. 11 shows the low thermal expansion layer 64 of FIG. 2 taken out. The low thermal expansion layer 64 of the present embodiment realizes a piezoelectric sensor structure with the aluminum nitride layers 102 and 104 sandwiched between electrodes 96, 98, and 100. The electrodes 96 and 100 are grounded by the ground terminal 108, and the center electrode 98 is connected to the signal output terminal 106 and taken out to the outside.

  The piezoelectric sensor having the laminated structure of the aluminum nitride layers 102 and 104 and the electrodes 96, 98, and 100 performs C-axis orientation of the aluminum nitride thin film so as to maintain the piezoelectricity of the aluminum nitride layers 102 and 104, and the metal It forms on the electrodes 96 and 98 used as foil.

  When such a low thermal expansion layer 64 has a piezoelectric sensor structure, as shown in FIG. 3, when the clearance is controlled by causing the medium relative surface 40 to project like the projecting portion 66 by energizing the heater coil 60, the magnetic disk When a collision with the protrusion 66 occurs due to the unevenness of the medium surface 14, the impact due to this collision is applied to the piezoelectric sensor structure constituting the low thermal expansion layer 64, and the voltage corresponding to the impact due to the collision due to the piezoelectric action is applied from the signal output terminal 106. Can be taken out.

  FIG. 12 is a cross-sectional view of another embodiment according to the present invention in which a low Young's modulus layer is disposed. 12, the magnetic head 18-4 of this embodiment has a read head 36 and a write head 38 disposed on the front side with respect to the substrate 34. The structures of the read head 36 and the write head 38 are the same as those of the embodiment of FIG. Similarly, a heater coil 60 for controlling the protruding amount of the medium facing surface 40 by thermal expansion is arranged.

  In the present embodiment, the low Young's modulus layer 84 is arranged after the shield layer 42 on the substrate 34 side in the read head 36, with respect to the basic shape composed of the read head 36 and the write head 38. It is connected to the substrate 34 via 84. The low Young's modulus layer 84 is made of a material having a low Young's modulus that can be easily deformed against thermal expansion when the heater coil 60 receives heat from energization heating.

  As the low Young's modulus layer 84, for example, a material having a Young's modulus that is one digit or two digits lower than the Young's modulus of each layer constituting the read head 36 and the write head 38, such as resist, polyimide, and amorphous fluororesin is used. is doing. The low Young's modulus layer 84 of this embodiment has a Young's modulus of 1 GPa to 50 GPa. The low Young's modulus layer 84 has a thickness of 0.4 μm to 4.0 μm, for example.

  FIG. 13 is an explanatory diagram of a protruding state due to thermal expansion when the heater coil 60 of FIG. 12 is energized. The magnetic head 18-4 of the present embodiment is a contact type magnetic head that performs writing and reading in a state where the medium relative surface 40 is always in contact with the medium surface of the magnetic disk 14.

  The contact type magnetic head 18-4 is characterized in that the medium facing surface 40 is locally projected as shown by a projecting portion 94 by thermal expansion due to energization heating of the heater coil 60. That is, the protrusion 94 comes into contact with the magnetic disk 14 with the peak amount at the lead gap position 68 and protrudes to a very close position at the write gap position 70 located on the front side, though not contacting.

  In the case of keeping the contact with the magnetic disk 14 by projecting by the thermal expansion by such energization control of the heater coil 60, in the rotary actuator 16 shown in FIG. It is desirable that 94 is in contact with the medium surface in a state where almost no pressing load is generated, and such a contact state is maintained by the balance of the rotary actuator.

  However, in the floating type magnetic head, for example, as shown in FIG. 3, the portion including the write gap position 70 and the read gap position 68 of the medium facing surface 40 is entirely projected by energization heating of the heater coil 60. In the case where the medium is brought into contact with the medium surface of the magnetic disk 14 in the same thermal expansion state as this, the relative area of the protrusions close to the medium surface increases.

  In the contact type magnetic head 18-4 as shown in FIG. 12, the distance between the head side and the magnetic disk 14 side is in a contact state, and this contact state is an interatomic state that causes an interaction between atoms. Power It is a world where the so-called Coulomb force acts.

  For this reason, when the medium relative surface 40 protrudes as a whole as a result of expansion as in the conventional floating head of FIG. 8, the relative area due to the protrusion with the disk surface increases, and the Coulomb force increases with the increase in area. The rotary actuator that brings the contact force to almost zero with the increase in the contact force loses balance, and the protruding contact by the heater coil is pressed against the disk surface with a strong force, causing problems such as head wear and disk surface wear, resulting in reduced durability. It will be.

  On the other hand, in the embodiment of FIG. 12, by providing the low Young's modulus layer 84, as in the heating energized state of FIG. On the side, a locally protruding portion 94 that protrudes greatly can be formed, the relative area with the magnetic disk 14 is reduced to suppress the increase of the Coulomb force, and the balance of the rotary actuator that maintains the medium contact of the magnetic head is maintained. be able to.

  FIG. 14 is a cross-sectional view of another embodiment of the present invention in which a low thermal expansion layer is disposed following a low Young layer. In FIG. 14, the magnetic head 18-5 of the present embodiment is the same as the embodiment of FIG. 12 in that the low Young layer 84 is disposed after the shield layer 42, but further, following the low Young layer 84. A low thermal expansion layer 94 is disposed between the substrate 34 and the substrate 34.

  Since the low thermal expansion layer 94 has a low expansion coefficient when receiving heat conduction due to the energization of the heater coil 60, the low thermal expansion layer 94 functions as a fixed portion with little deformation with respect to the low Young layer 84, thereby the read head 36 and the write head. The local protrusion on the side 38 is relatively large. Other structures are the same as those of the embodiment of FIG.

  FIG. 15 is an explanatory view showing the protruding position of the embodiment of FIGS. 12 and 14 in a high-temperature energized state that is the worst condition in comparison with the comparative example of FIG.

  In FIG. 15, the protruding position profile 88 is a case where the low Young's modulus layer is arranged in the basic shape of FIG. 12, and the protruding position profile 87 is a case where the low Young layer and the low thermal expansion layer of FIG. This is the case of the comparative example in which the position profile 86 does not have the low Young's modulus layer of FIG.

  As is apparent from the protruding position profile in the high-temperature energized state in FIG. 15, the head position protrudes as a whole for the protruding position profile 88 of only the basic shape having no low Young's modulus layer. With respect to the protrusion position profile 86 of the embodiment shown in FIG. 12, the protrusion amount rises substantially linearly before the lead gap position 68 and reaches a peak protrusion amount of about 6.8 nm, and then gradually increases toward the head tip. It is falling.

  Further, the protrusion position profile 87 of the embodiment provided with the low Young's modulus layer and the low thermal expansion layer of FIG. 14 rises substantially linearly after the protrusion amount shifts to the minus side before the lead gap position 68, and peak protrusion. The amount reaches around 6.3 nm, and then gradually decreases toward the head tip, and an effect of increasing local deformation due to the provision of the low thermal expansion layer is obtained.

  FIG. 16 shows the protruding position of the embodiment of FIGS. 12 and 14 when the heater coil is energized and heated at 100 mW in the high temperature energized state of FIG. 15 in comparison with the comparative example of FIG. In FIG. 16, the protrusion position profile 90 is a case where the low Young's modulus layer of FIG. 12 is provided, the protrusion position profile 91 is a case where the low Young layer and the low thermal expansion layer of FIG. 92 is the case of the comparative example which does not have the low Young's modulus layer of FIG.

  As is apparent from the measurement result of the protruding position in FIG. 16, when the low Young's modulus layer 84 is provided, it is almost linear before the lead gap position 68 as shown in the protruding position profile 90 by heating by energization of the heater coil. After that, it gradually increased and decreased.

  In addition, when a low Young's modulus layer and a low thermal expansion layer are provided, it increases almost linearly before the lead gap position 68 as shown by the protruding position profile 91 by heating by energization of the heater coil, and then gradually increases. Therefore, the deformation is suppressed by providing the low thermal expansion layer, and the projection amount profile 90 is lower than that when the low Young's modulus layer 84 is provided.

  Such a local protruding position profile greatly reduces the relative area associated with the contact with the disk medium in which the Coulomb force at the read gap position 68 and the write gap position 70 is a problem, and the rotary actuator in the contact type magnetic head. Contact balance due to balance can be maintained.

  Although the embodiment shown in FIGS. 12 and 14 is used as an example for a contact type magnetic head, it can be used for a floating type magnetic head and a near contact type because a local projecting profile can be used. A head structure in which a low Young's modulus layer 84 is similarly arranged for a (near contact-type) magnetic head.

  The invention is not limited to the above-described embodiments, and includes appropriate modifications that do not impair the objects and advantages thereof. Further, the present invention is not limited by the numerical values shown in the above embodiments.

Here, the features of the present invention are enumerated as follows.
(Appendix)

(Appendix 1)
A read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed on a substrate between a pair of shield layers, and a magnetic flux generated by a write current flowing in a write coil is recorded from the magnetic pole portion to the recording head. In a magnetic head in which a write head that emits information toward a medium and magnetically records information is sequentially arranged,
A heater coil that is disposed through an insulating layer with respect to the write coil, and that causes the medium relative surface to protrude toward the recording medium side by thermal expansion by energization overheating;
A low thermal conductive layer made of a material having a low thermal conductivity, which is arranged subsequent to the shield layer on the substrate side in the read head, and suppresses the propagation of heat due to energization overheating of the heater coil;
A low thermal expansion layer disposed on the substrate side of the low thermal conductive layer and made of a material having a low coefficient of thermal expansion;
A magnetic head comprising: (1)

(Appendix 2)
The magnetic head according to appendix 1, wherein the low thermal conductive layer is made of silicon oxide (SiO ₂ ) or a resin material. (2)

(Appendix 3)
In the magnetic head according to appendix 1, the low thermal expansion layer includes silicon carbide (SiC), silicon nitride (Si3N4), silicon oxide (SiO ₂ ), aluminum nitride (AlN), tungsten (W), molybdenum (M), A magnetic head comprising any one of Invar materials. (3)

(Appendix 4)
The magnetic head according to claim 1, wherein the low thermal expansion layer has a piezoelectric sensor structure in which an aluminum nitride layer is disposed between electrodes. (4)

(Appendix 5)
The magnetic head according to claim 1, wherein the low thermal expansion layer has a thermal expansion coefficient of 0.0 / K to 7.5E-6 / K.

(Appendix 6)
The magnetic head according to claim 1, wherein the low thermal conductive layer has a thermal conductivity of 0.1 W / m to 1.5 W / m.

(Appendix 7)
A read head in which a reading element for converting a recording magnetic flux emitted from the recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a magnetic flux generated by a write current flowing in a write coil is recorded from a magnetic pole portion. In a magnetic head in which a write head that emits information toward a medium and magnetically records information is sequentially arranged,
A heater coil that is disposed relative to the write coil via an insulating layer, and causes the medium relative surface to protrude toward the recording medium side by thermal expansion due to energization overheating;
A low thermal conduction layer made of a material having a low thermal conductivity, which is arranged subsequent to the shield layer on the substrate side in the read head, and suppresses the propagation of heat due to overheating of the heater coil;
A magnetic head comprising: (5)

(Appendix 8)
The magnetic head according to appendix 7, wherein the low thermal conductive layer is made of silicon oxide (SiO ₂ ) or a resin material. (6)

(Appendix 9)
The magnetic head according to claim 7, wherein the low thermal conductivity layer has a thermal conductivity of 0.1 W / m to 1.5 W / m.

(Appendix 10)
A read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a magnetic flux generated by a write current flowing in the write coil from the magnetic pole portion to the recording medium In a magnetic head in which a write head that emits information toward and magnetically records information is sequentially arranged,
A heater coil that is disposed through an insulating layer with respect to the write coil, and that causes the medium relative surface to protrude toward the recording medium side by thermal expansion due to energization overheating;
A low Young's modulus layer made of a material having a low Young's modulus, which is arranged subsequent to the shield layer on the substrate side in the read head and is easily deformable against thermal expansion;
A magnetic head comprising: (7)

(Appendix 11)
The magnetic head according to claim 10, further comprising a low thermal expansion layer that is disposed on the substrate side of the low Young layer and made of a material having a low coefficient of thermal expansion.

(Appendix 12)
The magnetic head according to appendix 10, wherein the low Young's modulus layer includes any of resist, polyimide, or amorphous fluororesin. (8)

(Appendix 13)
The magnetic head according to appendix 10, wherein the low Young's modulus layer has a Young's modulus of 1 GPa to 50 GPa. (8)

(Appendix 14)
The magnetic head according to appendix 10, wherein the low Young's modulus layer is formed by projecting a medium relative surface including the reading element and the recording element locally with respect to the substrate side by overheating of the heater coil. A magnetic head characterized by maintaining a contact state.

Explanatory drawing of a magnetic disk apparatus in which the magnetic head of the present invention is used Sectional drawing which showed embodiment of the magnetic head by this invention Explanatory drawing of protruding state due to thermal expansion when energizing heater coil The perspective view which showed this embodiment except the insulating layer Sectional view of FIG. 4 cut at the center position The perspective view which removed the write coil of FIG. 4, and showed arrangement | positioning of a heater coil Sectional drawing which showed other embodiment of the magnetic head by this invention which has arrange | positioned only a low heat conductive layer Sectional view showing a basic magnetic head without a low thermal conductive layer and low thermal expansion layer as a comparative example Explanatory drawing which showed the protrusion position of this embodiment with respect to the position of a medium relative surface in a high temperature energization state in contrast with a comparative example Explanatory drawing which showed the protrusion position of this embodiment at the time of energizing and heating a heater coil in the high temperature energization state of FIG. 9 in contrast with the comparative example. Explanatory drawing used as a collision sensor by arranging a piezoelectric sensor structure using aluminum nitride in the low thermal expansion layer Sectional view of another embodiment according to the present invention with a low Young's modulus layer Explanatory drawing of the protrusion state by thermal expansion at the time of supplying with electricity to the heater coil of embodiment of FIG. Sectional view of another embodiment according to the present invention in which a low thermal expansion layer is disposed following a low Young's modulus layer Explanatory drawing which showed the protrusion position of embodiment of FIG.12 and FIG.14 with respect to the position of the medium relative surface in a high temperature electricity supply state with a comparative example Explanatory drawing which showed the protrusion position of embodiment of Drawing 12 and Drawing 14 at the time of energizing and heating a heater coil in the high temperature energization state of Drawing 14 in contrast with a comparative example

Explanation of symbols

10: Magnetic disk device 12: Housing base 14: Magnetic disk 15: Shaft portion 16: Rotary actuator 18, 18-1 to 18-5: Magnetic head 20: Ramp load mechanism 22: Coil 24: Lower yoke 26: Magnet 32 : Disk moving direction 34: substrate 36: read head 38: write head 40: medium facing surfaces 42 and 44: shield layer 45: insulating layer 46: read element 48: magnetic pole part 50: inner magnetic pole 52: outer magnetic pole 54: write coil 54-1: Upper coil part 54-2: Lower coil part 55: Tip part 56: Write gap 58: Overcoat layer 60: Heater coil 62: Low thermal conductive layer 64, 85: Low thermal expansion layer 66, 94: Projection part 68 : Lead gap position (RG position)
70: Write gap position (WG position)
84: Low Young's modulus layer 96, 98, 100: Electrode 102, 104: Aluminum nitride layer 106: Signal output terminal 108: Ground terminal

Claims (8)

A read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed on a substrate between a pair of shield layers, and a magnetic flux generated by a write current flowing in a write coil is recorded from the magnetic pole portion to the recording head. In a magnetic head in which a write head that emits information toward a medium and magnetically records information is sequentially arranged,
A heater coil that is disposed through an insulating layer with respect to the write coil, and that causes the medium relative surface to protrude toward the recording medium side by thermal expansion due to energization overheating;
A low thermal conduction layer made of a material having a low thermal conductivity, which is arranged subsequent to the shield layer on the substrate side in the read head, and suppresses the propagation of heat due to overheating of the heater coil;
A low thermal expansion layer disposed on the substrate side of the low thermal conductivity layer and made of a material having a low coefficient of thermal expansion;
A magnetic head comprising:
)
2. The magnetic head according to claim 1, wherein the low thermal conductive layer is made of silicon oxide (SiO ₂ ) or a resin material.
2. The magnetic head according to claim 1, wherein the low thermal expansion layer includes silicon carbide (SiC), silicon nitride (Si3N4), silicon oxide (SiO ₂ ), aluminum nitride (AlN), tungsten (W), and molybdenum (M). A magnetic head comprising any one of Invar materials.
2. The magnetic head according to claim 1, wherein the low thermal expansion layer has a piezoelectric sensor structure in which an aluminum nitride layer is disposed between electrodes.
A read head in which a reading element for converting a recording magnetic flux emitted from the recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a magnetic flux generated by a write current flowing in a write coil is recorded from a magnetic pole portion. In a magnetic head in which a write head that emits information toward a medium and magnetically records information is sequentially arranged,
A heater coil that is disposed relative to the write coil via an insulating layer, and causes the medium relative surface to protrude toward the recording medium side by thermal expansion due to energization overheating;
A low thermal conduction layer made of a material having a low thermal conductivity, which is arranged subsequent to the shield layer on the substrate side in the read head, and suppresses the propagation of heat due to overheating of the heater coil;
A magnetic head comprising:
6. The magnetic head according to claim 5, wherein the low thermal conductive layer is made of silicon oxide (SiO ₂ ) or a resin material.
A read head in which a reading element for converting a recording magnetic flux emitted from a recording medium into an electric signal is disposed between a pair of shield layers on a substrate, and a magnetic flux generated by a write current flowing in the write coil from the magnetic pole portion to the recording medium In a magnetic head in which a write head that emits information toward and magnetically records information is sequentially arranged,
A heater coil that is disposed through an insulating layer with respect to the write coil, and that causes the medium relative surface to protrude toward the recording medium side by thermal expansion due to energization overheating;
A low Young's modulus layer made of a material having a low Young's modulus, which is arranged subsequent to the shield layer on the substrate side in the read head and is easily deformable against thermal expansion;
A magnetic head comprising:
  8. The magnetic head according to claim 7, wherein the low Young's modulus layer includes any one of resist, polyimide, and amorphous fluororesin.

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