US20080182484A1

US20080182484A1 - Lapping apparatus and lapping method

Info

Publication number: US20080182484A1
Application number: US12/020,704
Authority: US
Inventors: Koji Sudo; Yoshiaki Yanagida; Teruaki Nishioka
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Ltd
Priority date: 2007-01-30
Filing date: 2008-01-28
Publication date: 2008-07-31
Also published as: JP2008183665A

Abstract

A lapping apparatus includes a lapping plate having a lapping surface thereon that moves relative to a work. The lapping apparatus can adjust an inclination of the work in a latitudinal direction, thereby obtained preferable parallelization of both a reading elements and writing element to the lapping surface. As a result, the lapping apparatus can provide magnetic heads suitable for the perpendicular recording.

Description

This invention relates to a lapping apparatus and a lapping method using the apparatus.

BACKGROUND OF INVENTION

Recently, hard disk drives are in use as standard memory for video equipment as well as for personal computers. The hard disk drive has a relatively higher storage capacity than other storage devices. Thus video equipment built with a hard disk drive enable the user to record video images for a longer period of time compared to conventional equipment. In television broadcasting, a shift to digital terrestrial broadcasting transmitting various types and a large amount of information to viewers has been announced. The video equipment built with a hard disk drive allows viewers to record information as much as they want, including information broadcast via digital terrestrial broadcasting.
In view of this trend, it is desired to increase the capacity of the hard disk drive much further. However, a technology known as longitudinal magnetic recording applied to current hard disk drives is unable to increase the capacity of the hard disk drive any more because the capacity has been improved to its limit.
Therefore a recording technology called perpendicular magnetic recording has been proposed recently to replace the longitudinal magnetic recording and further increase the capacity of the hard disk. The perpendicular recording method produces magnetic paths in a depth direction of a hard disk's recording surface, not in a parallel direction, thereby recording information. Consequently, a magnetic domain is narrowed so that the storage capability of the hard disk drive is increased further than that of the conventional one.
The hard disk drive adopting the longitudinal magnetic recording conventionally uses a combination-type magnetic head having both a writing element (for writing) and a reading element (for reading). This combination-type magnetic head is required to comply with a strict measurement precision of a distance between a head of the writing element or a head of the reading element and the hard disk's recording surface to write or read information onto or from the recording surface compatibly when built in the hard disk drive. Therefore the conventional combination-type magnetic head is processed and finished to predetermined height by lapping apparatus (refer to patent literature 1-5).
1. Japanese Patent No. 3504105 (Counterpart of U.S. Pat. No. 5,899,793)
2. Japanese Patent No. 3589546 (Counterpart of U.S. Pat. No. 6,196,897)
3. Japanese Patent No. 3638815 (Counterpart of U.S. Pat. No. 6,315,636)
4. Japanese Laid-open Patent Publication No. 2005-339781 (Counterpart of U.S. Pat. No. 6,884,148)
5. Japanese Laid-open Patent Publication No. 2006-73088 (Counterpart of US Laid-open Patent Publication No. 2006-0044683)
Before describing the lapping method to fabricate the combination-type magnetic head to required dimension, a production process of the combination-type magnetic head will be explained briefly.
In fabricating the combination-type magnetic head, wafer processing is a first step. A plurality of the combination-type magnetic heads having both writing and reading elements are formed on a wafer two-dimensionally. Concurrently, resistance elements for the writing and reading elements called ELG are arranged in the vicinity of the heads (refer to patent literature 5). Since resistance values of these resistance elements vary in accordance with the amount of material removed by lapping, the lapping apparatus can perform proper lapping of the combination-type magnetic heads by reading the resistance values of these resistance elements.
During a second step, a plurality of the magnetic heads formed two-dimensionally are sliced to bars, thereby obtaining bar-shaped raw bars having the combination-type magnetic heads arranged in a row thereon. During a third step, each raw bar is affixed to the lapping apparatus, then a plurality of the magnetic heads arranged thereon are lapped to be finished all together. During lapping, each resistance value of the resistance elements for the reading or writing elements formed onto the wafer during the first processing are read by the lapping apparatus. When the resistance values read by the lapping apparatus reach a predetermined value, the lapping terminates as the writing and reading elements are processed to required specification. During a fourth step, the raw bars are diced to chips, thereby separating a plurality of the combination-type magnetic heads into individual heads.
A structure of the lapping apparatus for performing lapping of the raw bar as finishing will be described here.
FIGS. 1-5 show the structure of the lapping apparatus described in patent literature 1 and 2.
FIG. 1 shows lapping apparatus 1 having a lapping plate 10 and a lapping base 11. FIG. 2 shows a structure of an adaptor 12 having an arm 120 supported at a support point 1210 positioned on the lapping base 11 shown in FIG. 1 and extending downwards from the end of the arm 120 to keep an under surface of the work (the word “work” used herein means the raw bar. Hereinafter the work is sometimes called raw bar 100) contacting a lapping surface of the lapping plate 10. FIG. 3 shows an overhead view of the adapter 12 shown in FIGS. 1 and 2. FIG. 4 shows a mechanism of the lapping apparatus 1 that is used for both an inclination correction and a load adjustment. FIG. 5 shows a bend correcting mechanism of the lapping apparatus 1.
With reference to FIGS. 1-5, the appearance of the lapping apparatus will be briefly described.
The lapping apparatus 1 shown in FIGS. 1-5 is a lapping apparatus to provide lapping processing to the raw bar 100 using the adaptor 12 and the lapping plate 10 having a lapping surface thereon which moves relative to the raw bar 100. The lapping base 11 has bottom faces which can contact the lapping surface. The arm 120 is supported at the given support point 1210 (refer to FIG. 2) positioned on the lapping base 11 and extending in a horizontal direction from the support point 1210 and the supporting portion 121 extending downwards from the ends of the arm 120 to keep the raw bar 100 in contact with the lapping surface of the lapping plate 10. The adapter 12 has a holder 1201 as shown in FIGS. 2 and 3 and the raw bar 100 is bonded onto the holder 1201 with an adhesive or other bond.
The supporting portion 121 has a pivotable mechanism to set the work 100 closer to or further away from the lapping plate 10 by pivoting the arm 120. Before lapping, the arm 120 is pivoted upward and the raw bar 100 is bonded onto the holder 1201 attached to the adaptor 12. Then the arm 120 is pivoted downward so that the raw bar 100 is set onto the lapping surface of the lapping plate 10. Probes to read the resistance values of the resistance elements for the writing and reading elements are not illustrated, however, they are also attached onto the arm 120.
With reference to FIGS. 1-5, a structure of lapping apparatus 1 will be described.
The lapping apparatus 1 shown as in FIGS. 1-5 has the lapping base 11 fixed onto the lapping base 13 of the lapping apparatus as it pivots and oscillates freely (refer to FIG. 1) so that a degree of parallelization between the lapped surface of the raw bar 100 attached to the adaptor 12 and the lapping surface of the lapping plate 10 is maintained even where the lapping plate 10 oscillates to some degree when rotating.
The lapping apparatus 1 also has the load adjustment mechanism 14 to adjust lapping load onto the work 100 by applying the load from above the arm 120 for optimum lapping. When the lapping load is applied onto the work 100 via the adapter 12 by the load adjustment mechanism 14, the lapped surface of the raw bar 100 contacts the lapping surface of the lapping plate 10 steadily and stable lapping is performed. The load adjustment mechanism 14 of the lapping apparatus 1 shown in FIGS. 1-5 can correct an inclination of the bar-shaped work 100 shown as in FIG. 3 in a longitudinal direction, i.e. a differential in height between right and left, by disposing three actuators 141-143 in an orthogonal direction to a direction that the arm 120 shown in FIGS. 1 and 2 extends as shown in FIG. 4.
Having a regard to the characteristic of the raw bar 100's bar like shape and certain length in a longitudinal direction shown as in FIG. 3, the lapping apparatus 1 shown in FIG. 1 has the bend correction mechanism to correct wave undulation or bend resulting on the raw bar 100.
The lapping apparatus 1 adopts a bend correction mechanism described in patent literature 3. FIGS. 5A and 5B are outline drawings of the bend correction mechanism disclosed in patent literature 3. The wave undulation and bend resulting on the lapped surface can be corrected by pressing holes 1201 h on the holder 1201 onto a fixture 36, 38.
The holder 1201, bonded to the raw bar 100, is attached to the end of the arm 120 extending from the end of the adaptor 12 equipped on the lapping apparatus having the foregoing mechanisms. The arm 120 pivots about the support portion 121 (refer to FIG. 2) downwards to set the raw bar 100 against the lapping surface of the lapping plate 10.
Then the lapping load applied from above the arm 12 is adjusted by the load adjustment mechanism 14, the lapped surface of the raw bar contacts the lapping surface of the lapping plate 10 and proper lapping is performed.
When the raw bar 100 is lapping with the rotating lapping plate 10, the load adjustment mechanism 14 acts as the inclination correction mechanism and keeps the inclination of the raw bar 100 in the longitudinal direction parallel to the lapping surface of the lapping plate 10. The bend correction mechanism corrects the wave undulation and bend of the raw bar 100.
In addition to the load adjustment mechanism, the lapping base 11 is fixed onto the lapping base support portion 13 equipped on the lapping apparatus 1 as it rotates and oscillates freely as mentioned above so that the lapped surface of the work 100 is kept fitly touching the lapping plate 10. Thus the lapped surface of the raw bar 100 can be maintained parallel to the lapping surface of the lapping plate 10 even where a cut plane of the raw bar 100 changes as lapping progresses and preferable lapping is performed.
The strict requirement of the dimension of the combination-type magnetic head mentioned above will be outlined here.
FIG. 6 is a pattern diagram showing a cross-section view of the raw bar in its shorter side.
FIG. 6 shows a structure of the combination-type magnetic head arranged within the raw bar 100.
As shown in FIG. 6, the writing and the reading elements are produced apart from each other and the resistance elements for the writing element WR are arranged in their vicinity. The resistance elements for the reading elements RD are arranged in their vicinity. However, these resistance elements are not shown in FIG. 6. Lapping is performed in a direction shown by an arrow in FIG. 6 as resistance values of these resistance elements are read by the lapping apparatus 1 shown in FIGS. 1-5. Hence dimensions called an MR-h or a neck height shown in FIG. 6 are adjusted within a required tolerance.
For the hard disk drive adopting the conventional longitudinal magnetic recording, since the reading element RD requires more strict dimension precision than that of the writing element WR, the lapping apparatus 1 reads the resistance value of the resistance element for the reading element and when the resistance value of the reading elements reaches the required value lapping terminates. Consequently, the neck height of the writing element in the combination-type magnetic head used for the hard disk drive adopting the longitudinal magnetic recording can be processed within the tolerance automatically when lapping terminates when the resistance value of the reading element reaches the required value. That is to say if the lapped surface of the combination magnetic head is beveled slightly in a latitudinal direction (a direction of the reading elements and writing element arranged in a row), it poses no problem for the combination-type magnetic head used for the hard disk drive adopting the longitudinal magnetic recording.
However, the perpendicular magnetic recording produces narrower magnetic domains as described above. Thus, not only the dimension of the reading element called the MR-h but also the dimension of the writing element called the neck height require stricter dimension precision.
As a result, it is not tolerable that the lap surface of the combination-type magnetic head shown as in FIG. 6 inclines to the lapping surface of the lapping plate in a latitudinal direction (the direction of the reading and writing elements arranged in a row) as in conventional manner. Thus the conventional lapping apparatus 1 as illustrated in FIGS. 1-5 cannot process the combination-type magnetic head used for the hard disk drive adopting perpendicular magnetic recording.

SUMMARY

In accordance with an aspect of an embodiment, a lapping apparatus for lapping a work includes a lapping plate having a lapping surface thereon that moves relative to the work. A lapping base has a bottom face contacting the lapping surface of the lapping plate. An adaptor having an arm supported at a given support point positioned on the lapping base extends in a horizontal direction from the support point and a supporting portion extends downwards from an end of the arm for holding an under surface of the work contacting the lapping surface. A tilt mechanism adjusts a contact angle of the work held by the supporting portion with the lapping surface of the lapping plate by adjusting a height of the support point positioned under the adaptor. In addition, in accordance with an aspect of another embodiment, a lapping method to lap a work including steps of contacting the work in which a plurality of heads are arranged along the longitudinal direction on a lapping surface of a lapping plate, rotating the lapping plate and lapping the work, and adjusting the contact angle of the lapped surface to the lapping surface about latitudinal direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the perspective view of the conventional lapping apparatus.

FIG. 2 is the side view of the adapter of the conventional lapping apparatus.

FIG. 3 shows the holder and the raw bar bonded to the holder.

FIG. 4 shows the inclination correction mechanism.

FIGS. 5A and 5B show a detailed structure of the holder.

FIG. 6 shows a pattern diagram of the raw bar 100's cross-section surface.

FIG. 7 shows a structures of a lapping base 11 a and an adopter 12 a in a lapping apparatus 1 a which is one embodiment of this invention.

FIG. 8 illustrates a structure of a control device 1000 a in the lapping apparatus 1 a.

FIG. 9 shows transition of the raw bar 100's form during lapping performed by control sections in the control device 1000 a.

DETAILED DESCRIPTION

The embodiment of this invention will be described hereinafter.
FIG. 7 shows the structures of the lapping base 11 a and the adopter 12 a in the lapping apparatus 1 a which is one embodiment of this invention.
In addition to the conventional structure, a linearlinear actuator 130 is added to the supporting portion 121 as a tilt mechanism as shown in FIG. 7.
The lapping base 11 a has a pivot PB supporting a support point 1210 a located under the adaptor 12 a. The tilt mechanism 130 is a linearlinear actuator having a body and a rod controlled its stroke length from the body by a control signal. The body of the linearlinear actuator 130 is embedded in an arm 120 a and the rod of the linearlinear actuator 130 touches and pushes the pivot PB with its head to adjust a height of the support point 1210 a finely. A stroke length of the linearlinear actuator is determined and fixed by using an optical flat method disclosed in patent literature 1 to parallelize the lapped surface of the raw bar 100 to the lapping plate before lapping. In this case, a linearlinear actuator MSD-23D23H10 (1 μm resolution, 10 mm stroke) manufactured by Chiba Seimitu Colo., LTD is used. When the support point 1201 a raises 200 μm from the predetermined height by protruding the rod of the linearlinear actuator 130, a differential between the reading elements RD and the writing element WR arranged in a row in a latitudinal direction can be measured. The linearlinear actuator 130 can accommodate a stroke of its rod by 1 μm as a minimum resolution so that the differential in height between the reading elements RD and the writing element WR can be reduced to less than 0.05 nm.
In other words, the linearlinear actuator 130 having the structure shown in FIG. 7 can adjust the inclination in a latitudinal direction shown in FIG. 6, thereby obtaining preferable parallelization of both the reading elements RD and writing element WR to the lapping surface.
FIG. 8 shows the structure of the control device 1000 a in the lapping apparatus 1 a.
The control device 1000 a shown in FIG. 8 has a CPU 1001 a. The CPU 1001 a drives each adjustment mechanism of each control section by executing processing programmed in a memory 1002 a in sequence.
The control device 1000 a shown in FIG. 8 has a common mechanism control section 1003 a therein to control a motor rotating the lapping plate 10 or to pour abrasive slurry onto the lapping plate 10. This common mechanism control section 1003 a has a driver to drive a motor within a lapping plate rotating mechanism 170 and a drive section to drive an electromagnetic valve in a slurry switching mechanism 160. When a command is sent from the CPU 1001 a to the driver or the drive section in the common mechanism control section 1003 a, the motor within the lapping plate rotating mechanism 170 a rotates the lapping plate 10. At the same time, the electromagnetic valve within the slurry control device 160 opens to pour the slurry onto the lapping plate 10 and then lapping starts.
When the lapping plate 10 rotates and the lapping of the raw bar 100 starts, the resistance values of both reading elements and writing element within the raw bar 100 are read by an ELG resistance measure 150 under a control of the CPU 1001 a.
The CPU 1001 a executes commands to remove noise impeding the reading by a denoising section 1004 a in the lapping apparatus 1 a, reading correct resistance values of each resistance element on individual combination-type magnetic heads arranged in the raw bar one by one. Based on the result of the bar-shape forming, the CPU 1001 a command an inclination correction mechanism 14 via an inclination correction control section 1005 a to correct an inclination between the right and left ends of the raw bar in the longitudinal direction. The CPU 1001 a also commands the bend correcting mechanism (refer to FIGS. 5A and 5B) via a bend control section 1007 a to correct the wave undulation or bend (which is equivalent to the word “bend” used herein) of the raw bar. In addition, the CP 1001 a commands the tilt mechanism 130 via a tilt mechanism control section 1006 a to correct the inclination of the raw bar in a latitudinal direction based on the result of foregoing processings. The slurry switching mechanism 160 and rotating mechanism 170 are controlled by common mechanism control section 1003 a.
FIG. 9 shows a raw bar's form transition during the lapping processing performed by each control section of the control device 100 a shown in FIG. 8.
At the top right of FIG. 9, a cross-section view of the work, i.e., the raw bar 100, before the foregoing correcting processing is applied thereto by the inclination correcting mechanism 14, the bend correction mechanism 110 (refer to FIGS. 5A and 5B) or the tilt mechanism 130 controlled by each control section. Under the cross-section view, cross-section views of the work after any of foregoing correction is applied.
The form of the raw bar 100 before lapping is a trapezoid as shown at the top right. Whereas the raw bar is lapped to a symmetrical square and the lapped surface of the combination-type magnetic head having the reading elements RD and writing element WR is parallelized as much as possible to the lapping surface at the end of the processings.
With reference to the cross-section views of FIG. 9 from the top to bottom, the transition of the raw bar 100's form will be explained.
First, the CPU 1001 a equipped in the control device 1000 a derives a bar like form from the resistance values of the resistance elements for the reading elements measured by the ELG resistance measure 150 and produces an image of the bar like shape shown at the top right. The illustration at the top right of FIG. 9 shows a form of the raw bar before lapping.
Recognizing the raw bar's form is as the trapezoid as shown at the top right of FIG. 9, the control device 1000 a commands the inclination correction mechanism 14 to correct the inclination in the longitudinal direction via the inclination correction control section 1005 a. The control device 1000 a also commands the bend correction mechanism 110 (refer to FIGS. 5A and 5B) to correct the wave undulation or bend via the bend control section 1007 a. Thus the lapped surface of the raw bar 100 becomes flatter than the surface before lapping shown as in the second cross-section view. Then the wave undulation or the bend is corrected by using only the bend correcting mechanism so that a given differential between the reading elements RD and the writing element WR is produced. When the differential becomes parallel, the tilt mechanism 130 adjusts the contact angle and then lapping is applied to parallelize both reading elements RD and the writing element WR to the lapping surface.
Conventional lapping processing terminates at a level shown as in the second cross-section view so that a required precision of the combination-type magnetic head for the hard disk drive adopting the perpendicular magnetic recording cannot be satisfied. However, an adoption of the tilt mechanism enables processing of the combination-type magnetic head for the hard disk drive adopting the perpendicular magnetic recording to a level shown at the bottom of FIG. 9. Thus the combination-type magnetic head used in the hard disk drive adopting perpendicular magnetic recording is lapped precisely.
In this embodiment, a contact angle of the raw bar's lapped surface with the lapping surface can be adjusted gradually by 0.005 degrees at 3 second intervals by the tilt mechanism, through the linearlinear actuator 130. Configuring the resolution to adjust the contact angle by micro-degrees enables lapping to parallelize both reading elements and writing element on the lapped surface as much as possible to the lapping surface of the lapping plate. In addition, this configuration to adjust the contact angle with the tilt mechanism also protects the lapping plate from suffering damage during lapping.
To protect the lapping plate from damage, it is effective to configure the load adjustment mechanism illustrated in FIG. 4 to reduce the load onto the work 100 before adjusting the contact angle by activating the tilt mechanism, i.e. the linearlinear actuator 130. The lapping plate 10 can also be protected from damage by having the driver in the common mechanism control section 1003 a reduce the speed of the motor in the lapping plate rotating mechanism or stopping the motor when adjusting the contact angle by the tilt mechanism 130.
The control section 1000 a has an operating section OP1 as shown in FIG. 8 so that the contact angle can be better set to perform preferable lapping. Thus, where an operator decides to perform further finishing after a parallelization between the reading components RD and the writing components WR with a CCD camera, the operator can configure the contact angle by the operation section OP1 to perform lapping as necessary by the lapping apparatus 1.
Highly accurate lapping processing for the combination-type magnetic head used in the hard disk drive adopting the perpendicular magnetic recording can be realized in the manner described above.

Claims

1. A lapping apparatus for lapping a work, comprising:

a lapping plate having a lapping surface thereon that moves relative to the work;

a lapping base having a bottom face contacting the lapping surface of said lapping plate;

an adaptor having an arm supported at a given support point positioned on said lapping base and extending in a horizontal direction from the support point and a supporting portion extending downwards from an end of the arm for holding an under surface of the work contacting with said lapping surface; and

a tilt mechanism for adjusting a contact angle of the work held by said supporting portion with said lapping surface of the lapping plate by adjusting a height of said support point.

2. The lapping apparatus according to claim 1,

wherein the work has a rectangle shape, and when the work is held by said supporting portion the work's longitudinal axis extends in a direction which crosses the direction in which said plate extends; and

wherein said tilt mechanism adjusts an inclination of the lapped surface of the work to said lapping surface in a latitudinal direction.

3. The lapping apparatus according to 2,

wherein said lapping base has a pivot to support the support point positioned under said adaptor; and

wherein said tilt mechanism is a linear actuator having a body and a rod that controls the position of the body by a control signal, the body being embedded in the arm, and a head of the rod touching the pivot to adjust a height of the support point positioned under the adaptor finely according to the stroke length of the rod.

4. The lapping apparatus according to claim 2, further comprising:

a plurality of actuators arranged in a horizontal direction to apply a load from above said plate; and

an inclination correcting mechanism to correct the inclination of the lapped surface of the work to said lapping surface of the lapping plate in a longitudinal direction by adjusting distributed lapping load in said second horizontal direction.

5. The lapping apparatus according to claim 2, further comprising:

a holder which the work is bonded, wherein the work is affixed to said holder and the work is held by said support point positioned under the lapping plate by attaching said holder to said supporting portion, wherein said holder has a bend correcting mechanism to correct a bend of the work.

6. The lapping apparatus according to claim 2,

wherein the work has a writing element and a reading element separately arranged in a latitudinal direction thereof, a plurality of the writing elements and the reading elements are arranged in a longitudinal direction, and the work has a plurality of resistance elements for said writing elements and read elements whose resistance values vary as lapping is progressing; and

wherein said tilt mechanism adjusts the inclination of the lapped surface of the work to the lapping surface in the latitudinal direction based on resistance values of said resistance element for the writing element and of the resistance element for the reading element.

7. The lapping apparatus according to claim 2, further comprising:

a control device to adjust the inclination of the lapped surface of the work to said lapping surface of the lapping plate in the latitudinal direction by controlling the tilt mechanism according to a value configured by a user.

8. A lapping method to lap a work comprising steps of:

contacting the work in which a plurality of heads are arranged along the longitudinal direction on a lapping surface of a lapping plate;

rotating the lapping plate; and

lapping the work, adjusting the contact angle of the lapped surface of the work to the lapping surface about a latitudinal direction.

9. The lapping method according to claim 8, further comprising a step of:

adjusting a lapping load on the work by applying the load from above said plate before adjusting the contact angle.

10. The lapping method according to claim 8, further comprising a step of:

adjusting a speed of said lapping plate before adjusting the contact angle.

11. The lapping method according to claim 8, wherein said adjusting step adjusts the contact angle gradually by a degree greater than 0, and equal or less than 0.01 degree at a time.

12. The lapping method according to claim 8,

wherein said adjusting step adjusts inclination of the lapped surface of the work to the lapping surface in the latitudinal direction based on the resistance values of the resistance elements.