JP2005156551A - Flatness measuring device of workpiece equipped with workpiece pedestal, and the workpiece pedestal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a workpiece pedestal to inhibit generation of ESD and adhesion of dust, by making a contact area small and maintaining a stable support status on the workpiece. <P>SOLUTION: In the case of a flatness test, a central convex part 22 of a flat column-shaped pedestal body 21 is fixed on a hole part Wa of an annular shape workpiece W. Then, on the work-piece pedestal which supports horizontally at the inner circumference of the work-piece W from downward by an annular face 21a which encloses the central convex part 22, the fine projections 24A(64A)(74A) with their edges having the sharp points are allotted and formed to all regions equally at the annular face 21a in the pedestal body 21, the tops 24a(64a)(74a) of the fine projections 24A(64A)(74A) are set as a workpiece support face. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a work cradle used in a process of inspecting the flatness of a donut-shaped disk substrate such as a platter for a hard disk device, and a work flatness measuring apparatus including the work cradle.

  In the manufacturing process of a hard disk or the like, for example, there is a process of polishing both surfaces of a workpiece that is a substrate of a Ni-P aluminum magnetic disk. However, with the current technology, there is a limit to polishing both surfaces of the workpiece uniformly and with high accuracy, which causes a slight difference in film thickness, which tends to cause warpage and deformation of the workpiece. . Therefore, the flatness (warping amount) is inspected for the workpiece that has undergone the polishing step, and it is determined whether or not it falls within a certain standard.

  In general, this kind of flatness measuring apparatus for workpieces includes a workpiece cradle 100 as shown in FIGS.

  This work cradle 100 is a central convex part 102 fitted in a hole Wa of a donut-shaped work (see FIG. 1) W at the center of a flat cylindrical cradle base 101 made of metal such as SUS when flatness is measured. Are formed integrally, and a Cr plating layer 101a is formed on the surface, and the inner peripheral portion of the workpiece W is horizontally supported from below by an annular surface 103 surrounding the central convex portion 102 of the cradle base 101. The flatness of the workpiece W is measured by a known measuring unit using a laser or the like.

In addition, there exists a thing as described in the following patent documents 1 and 2 as a chucking method of donut type | mold work.
JP 2000-166627 A JP 2000-308508 A

  However, in the conventional work cradle, the entire annular surface 103 surrounding the central convex portion 102 of the cradle base 101 is a work support surface that comes into surface contact with the inner peripheral portion of the work W. Not much dust adheres.

  If the workpiece W is supported while dust is adhered to the annular surface 103, fine scratches may be formed on the workpiece W due to the weight of the workpiece W, and the dust is transferred and adhered to the workpiece W. May remain. In addition, arc discharge may occur due to the dust charged at that time, and electrostatic breakdown (ESD) may occur.

  The flatness measurement / inspection is performed in a clean room in order to avoid dust adhering to the work W as much as possible. Even in a clean room, there are a few suspended particles (particles). If these measures are not taken, the above problem cannot be solved.

  An object of the present invention is to reduce a contact area without impairing a stable support state for a workpiece, and to prevent the adhesion of dust and the occurrence of ESD, and the flatness measurement of a workpiece equipped with the workpiece cradle. To provide an apparatus.

The present invention solves the above problems by providing the following means. That is,
[1] At the time of measuring the flatness, the central convex portion of the flat cylindrical cradle base is fitted into the hole portion of the donut-shaped workpiece, and the inner peripheral portion of the workpiece is horizontally arranged from below by the annular surface surrounding the central convex portion. In the supporting work cradle,
A minute protrusion having a sharp point is formed on the annular surface of the cradle base so as to be evenly distributed over the entire area, and a surface formed by the top of the minute protrusion is set as a work support surface. Work cradle.

  [2] The work cradle according to item 1 above, wherein the minute protrusion is formed integrally with the cradle base.

  [3] The workpiece cradle according to item 1 or 2, wherein the top of the minute protrusion is a convex curved surface.

  [4] The workpiece cradle according to item 3 above, wherein the top of the minute protrusion is selected from a range of a radius of curvature of 0.01 to 1 mm.

  [5] The work cradle according to any one of [1] to [4], wherein the minute protrusion includes an annular ridge that is continuous in a circumferential direction of the cradle base.

  [6] The work cradle according to any one of [1] to [4], wherein the minute protrusion is configured by an arc-shaped ridge that is intermittently spaced in a circumferential direction of the cradle base.

  [7] The work cradle according to item 5 or 6, wherein the protrusions are arranged in a plurality of rows in the radial direction of the cradle base.

  [8] The work cradle according to any one of items 1 to 7, wherein the constituent material of the cradle base is a hard synthetic resin.

  [9] The work cradle according to item 8, wherein the constituent material of the cradle base is a polyether / ether / ketone resin.

[10] At the time of measuring the flatness, the central convex portion of the flat cylindrical cradle base is fitted into the hole of the donut-shaped workpiece, and the inner peripheral portion of the workpiece is horizontally arranged from below by the annular surface surrounding the central convex portion. Supporting workpiece cradle;
A workpiece delivery means for holding the workpiece fed from the previous process and delivering it to the cradle;
Flatness detecting means for detecting the flatness of the workpiece when the workpiece is placed on the cradle;
With
A minute protrusion having a sharp point is formed on the annular surface of the cradle base so as to be evenly distributed over the entire area, and a surface formed by the top of the minute protrusion is set as a work support surface. Workpiece flatness measuring device.

  According to the invention [1], since the surface constituted by the tops of the minute protrusions formed on the annular surface of the cradle base is used as the work support surface, the contact area with respect to the work is remarkably reduced and floats on the work support surface. The amount of dust such as fine particles attached becomes extremely small. For this reason, it is possible to eliminate the possibility that dust is transferred to and adhered to the supported workpiece, or that the workpiece is damaged by the dust, and further, the electric power generated between the workpiece and the cradle base by the minute protrusion is reduced. Since it is dispersed, the occurrence of ESD can be suppressed, whereby the flatness can be properly measured without damaging the workpiece, and the yield of the workpiece can be increased.

  According to the invention [2], since the minute protrusion is integrally formed on the cradle base, the minute protrusion can be easily formed by, for example, cutting.

  According to the invention [3], since the top of the minute protrusion is formed of a convex curved surface, the contact area with the workpiece can be reliably reduced while preventing the workpiece from being damaged.

  According to the invention [4], since the curvature radius of the top of the fine protrusion is selected and set from a range of 0.01 to 1 mm, contact with the workpiece while maintaining the machining accuracy of the fine protrusion. The area can be reduced.

  According to the above invention [5], since the minute protrusion is constituted by the annular protrusion that is continuous in the circumferential direction, the protrusion can be supported in a line contact state with respect to the workpiece, and the protrusion can be formed by cutting or the like. There is an advantage that it can be formed easily.

  According to the invention [6], since the minute protrusions are constituted by arc-shaped protrusions that are intermittently spaced in the circumferential direction, the contact area with the workpiece can be further reduced.

  According to the invention [7], since the protrusions are arranged in a plurality of rows in the radial direction of the cradle base, the support state of the workpiece becomes stable.

  According to the invention [8], since the constituent material of the cradle base is a hard synthetic resin, it is difficult to be scratched, the durability can be improved, and it can be provided at a relatively low cost.

  According to the invention [9], since the constituent material of the cradle base is a polyether-ether-ketone resin, fatigue resistance and wear resistance are improved.

  According to the invention [10], by providing the work cradle, the flatness inspection of the work can be properly executed without causing problems such as adhesion of dust to the work.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an external perspective view showing a flatness measuring apparatus provided with a work cradle according to the present invention. Note that the basic configuration and operation of the flatness measuring apparatus are the same as those known in the art, and therefore will be schematically described.

  In addition, the workpiece W such as a magnetic disk substrate, which is an object to be measured, here is, for example, one having a thickness of 0.8 mm, a diameter of 84 mm, and a diameter of the hole Wa of about 25 mm. However, it is not limited to this.

  In FIG. 1, the flatness measuring apparatus generally includes an apparatus main body 1, a work support 3, a work delivery unit 4, and a flatness detection unit 5 that detects the flatness of the work W.

  The apparatus body 1 includes an upper substrate 13 supported on a lower substrate 11 via a plurality of support columns 12 and a pedestal 14 having a rectangular planar shape fixed on the upper substrate 13. An origin side reference base 15 is disposed on one end side in the longitudinal direction (X-axis direction) on the pedestal 14, and a forward reference is provided on the other end side of the pedestal 14 so as to face the origin side reference base 15. A table 16 is arranged.

  Guide rails 17 extending along the longitudinal direction are fixed on the upper substrate 13 and located on both sides of the pedestal 14 in the width direction. The guide rails 17 are driven by a driving device (not shown). The slider 18 is slidably fitted.

  The origin-side reference table 15 and the forward-side reference table 16 are used to determine the scan start and end positions when the measurement head, which will be described later, scans the workpiece W by a predetermined range in the X direction.

  The workpiece support 3 is disposed between the origin-side reference table 15 and the forward-side reference table 16, and the workpiece support 2 that horizontally supports the inner peripheral portion of the workpiece W from below, A disk base 32 to which the work cradle 2 is fixed by screws 31 and the like, and a work W that is carried in a position that surrounds the work cradle 2 on the same axis so as to be movable up and down (Y-axis direction). Are provided on the workpiece cradle 2, and a lifting / lowering drive cylinder 34 of the cup member 33 is provided.

  The disk base 32 is attached to the base 14 side in a replaceable manner by screws (not shown) or the like.

  As shown in FIGS. 2 (A) and 2 (B), the cup member 33 is connected to the piston of the cylinder 34 via a reverse gate-shaped connecting member 35 that is arranged to pass through the pedestal 14 so as to be movable up and down. As shown in FIG. 2 (A), the workpiece W, which is connected to the tip end of the rod 34a, is received at the lifted position where the piston rod 34a is extended, and the piston rod 34a is contracted. As shown in FIG. 2 (B), the workpiece W is transferred to the workpiece cradle 2. In FIG. 2, reference numeral 36 denotes an ionizer disposed so as to face the upper surface of the work cradle 2.

  The workpiece transfer unit 4 is disposed, for example, on the other end side in the longitudinal direction of the apparatus main body 1 and is disposed between the reversing hand mechanism 41, the driving unit 42 of the reversing hand mechanism 41, and the reversing hand mechanism 41 and the driving unit 42. There is provided a joint mechanism 43 that is interposed so as to connect the reversing hand mechanism 41 so as to be reversible within a vertical plane along the Z axis.

  The reversing hand mechanism 41 has a pair of left and right hand members 44, 44 for sandwiching the work W from the outside in the radial direction. For example, the reversing hand mechanism 41 receives the work W supplied from the previous process in a predetermined posture, and in a reversed posture. The workpiece W is configured to be transferred to the cup member 33 and is configured to be advanced to a position where the workpiece W is transferred to the cup member 33 in an inverted posture.

  The flatness detection unit 5 is provided across the sliders 18 and 18 and is driven by a driving device (not shown) to irradiate the workpiece W with laser light. The plurality of sensors 52 and the cover 53 are provided, and the entire surface of the workpiece W is scanned as the slider 18 moves. For example, reflected light from the workpiece W caused by laser light irradiation and reference light are caused to interfere with each other, and the flatness of the workpiece W is detected from the phase change of the interference light. Of course, the configuration of the flatness detection unit 5 can employ any configuration such as a method using eddy current.

  The work cradle 2 is formed by integrally forming a circular central convex portion 22 that fits into a hole Wa of the work W on the upper surface of a flat cylindrical base 21 made of synthetic resin, for example. A screw insertion hole 23 is formed in the center of the base body 21 so as to penetrate the mounting screw 31 through the thickness direction (vertical direction).

  The size of the cradle base 21 is 30 mm in diameter, 7.5 mm in height, 24 mm in the diameter of the central protrusion, and about 1 mm in the height of the central protrusion 22. It can be changed according to the size of the workpiece W.

  The synthetic resin constituting the cradle base 21 includes, for example, an acrylic resin. In this example, a hard synthetic resin having excellent hardness, for example, a crystalline polymer having a combined structure of pheniketone and phenyl ether is used. Thus, it is possible to obtain a higher hardness than that using an acrylic resin or the like.

  Of the crystalline polymers, it is preferable to use a PEEK (polyether ether ketone) resin having the most excellent fatigue resistance and environmental resistance. This corresponds to what is called engineering plastic, which is a kind of special plastic.

  In order to make the contact surface with the workpiece W as small as possible in the entire area of the annular surface 21a surrounding the circular convex portion 22 in the cradle base 21, as shown in FIG. 5, the height is about 0.5 mm. A fine protrusion 24 having a sharp point is formed.

  The minute protrusions 24 are composed of, for example, minute protrusions 24A and 24A that are continuous in the circumferential direction of the cradle base 21 and have two rows of triangles in the radial direction, and these protrusions 24A and 24A. Each top part 24a is configured as a work support surface that supports the lower surface of the inner peripheral part of the work W from below. The ridges 24A and 24A can be formed separately from the cradle base 21, but in this example, the cradle base 21 is integrally formed by cutting, so that it has high accuracy. Can be processed. Of course, the formation of the protrusions 24A and 24A is not limited to the cutting method.

  Next, a procedure for measuring the flatness of the workpiece W will be briefly described.

  In the flat inspection standby state, as shown in FIG. 2A, the piston rod 34 a of the cylinder 34 is extended, and the cup member 33 is set at a raised position higher than the workpiece cradle 2.

  When the workpiece W fed from the previous process is held by the hand members 44 and 44 from the outer periphery side, the hand members 44 and 44 are reversed to move the workpiece W to the cup member 33. Delivered. When the cup member 33 receives the workpiece W, the piston rod 34a of the cylinder 34 contracts, so that the cup member 33 moves downward, and accordingly, the workpiece W of the cup member 33 is placed on the workpiece cradle 2. Is done.

  Thereafter, the measuring head 51 moves to a predetermined position via the slider 18 driven by the head driving device, scans the workpiece W placed on the workpiece cradle 2, and the sensor 52 flattens the workpiece W. The degree is measured according to a known operation.

  When the flatness inspection is completed, the cup member 33 is raised, and the work W on the work cradle 2 is supported by the cup member 33 accordingly. Then, the workpiece W held by the cup member 33 is gripped by the hand members 44 and 44 before feeding to the next process.

  By the way, when the workpiece W is transferred to the workpiece cradle 2 by the cup member 33, the workpiece W is, as shown in FIG. 6, the top portions 24 a of the two rows of protrusions 24 </ b> A and 24 </ b> A in the workpiece cradle 2. Thus, the workpiece support 2 is supported in a line contact state. The protrusions 24A and 24A are not particular about two rows, but the support state of the workpiece W is stabilized when there are two rows.

  In the clean room for measuring the flatness, there are a few suspended fine particles, but since the work supporting surface is constituted by the top portions 24a of the ridges 24A and 24A, most of the suspended fine particles do not stay at the top portions 24a. . For this reason, there is no possibility that the work W is damaged by suspended fine particles or the like while the work W is supported.

  Further, the contact surface with the workpiece W is dispersed over the entire area by the top portions 24a of the ridges 24A and 24A, so that the electric power generated between the two ridges 24A and W is dispersed. Therefore, the occurrence of ESD and the like is suppressed, and accordingly, the flatness can be properly measured without the possibility of a defect occurring in the workpiece W, thereby increasing the yield.

  The protrusion 24A is not limited to a triangular cross section as long as the tip is sharp, but if it is a triangular shape, it is less likely to be inadvertently broken during cutting.

  By the way, the protrusion 24A, 24A can reduce the contact surface with the workpiece W as the tip is sharpened. In addition to being difficult to form, wear and buckling deformation due to repeated contact with the workpiece W occur and become cheap, which is not preferable. In consideration of this point, in this example, the top 24a of the protrusion 24A is formed by a convex curved surface as clearly shown in FIGS.

  In order to achieve both reduction in the contact area with respect to the workpiece W and processing accuracy, the radius of curvature R of the top 24a is preferably selected from a range of 0.01 to 1 mm, and preferably 0.02 to 0. 0.5 mm, more preferably 0.05 to 0.15 mm.

  As a result of suppressing the adhesion of dust to the workpiece W in this flatness inspection, it is possible to omit the step of cleaning the workpiece W again for dust removal after the inspection.

  FIGS. 7 to 9 show modifications of the work cradle 2, respectively, and the same or corresponding parts as those in FIGS.

  7-9, the microprotrusions 24 are arranged in a plurality of rows in the radial direction of the cradle base 21, and from a plurality of arc-shaped ridges 64A... Intermittently spaced in the circumferential direction. Therefore, the top 64a of the protrusion 64A is configured as a work support surface.

  When such a workpiece cradle 2 is used, the same effect as described above is exhibited, and apart from the cutting workability of the protrusion 64A, the contact area with the workpiece W is reduced, and the adhesion of dust is further reduced. .

  10 to 12 show other modified examples of the work cradle 2, and the same or corresponding parts as those in FIGS. 3 to 6 are denoted by the same reference numerals and description thereof is omitted.

  10 to 12, the minute protrusion 24 includes a plurality of protrusions 74 </ b> A that are equally distributed in the circumferential direction of the cradle base 21 and extend radially, and the top 74 a of the protrusion 74 </ b> A is configured as a work support surface. ing.

  In this case as well, although there is a surface that makes it difficult to make the height of the protrusion 74A highly accurate by the cutting method, the contact surface with the workpiece W can be reduced.

  The minute protrusions 24 are not limited to the protrusions 24A (64A) (74A) as described above, but may be a number of pin-shaped minute protrusions that make point contact with the workpiece W. However, from the viewpoint of being easily formed integrally with the cradle base 21a by, for example, cutting or the like, the ridges 24A (64A) and (74A), in particular, the ridges 24A are recommended.

  Next, examples will be described.

  Two rows of protrusions continuous in the circumferential direction were formed by cutting on an annular surface of a pedestal base made of PEEK resin having a diameter of 30 mm and a height of 7.5 mm. The height of the ridge was 0.5 mm (± 0.01 mm), and the radius of curvature at the top was 0.1 mm. Using the workpiece cradle, the flatness inspection was performed. In this case, it was confirmed that defects such as scratches on the workpiece did not occur until 500,000 workpieces were inspected.

Comparative example

  The flatness inspection was performed using a work cradle having a hard Cr plating layer formed on the surface of a SUS cradle base having a diameter of 30 mm and a height of 7.5 mm. In this case, when 5000 workpieces were inspected, the work was damaged by the suspended fine particles adhering to the workpiece cradle, and the workpiece cradle had to be replaced.

It is an external appearance perspective view which shows the flatness measuring apparatus provided with the workpiece cradle concerning embodiment of this invention. (A) It is explanatory drawing of the standby state which mounts a workpiece | work on a workpiece cradle with the cup member in a flatness measuring device.

(B) It is explanatory drawing of the state which mounts a workpiece | work on a workpiece cradle with the cup member in a flatness measuring device.
It is a top view which shows a workpiece cradle. It is sectional drawing along the AA line of FIG. FIG. 5 is an enlarged cross-sectional view of a portion V in FIG. 4. It is explanatory drawing of the top part shape of the protrusion in a workpiece | work cradle. It is a top view which shows the modification of a workpiece cradle. It is sectional drawing along the BB line of FIG. It is an expanded sectional view of the part of IX of FIG. It is a top view which shows another modification of a workpiece | work cradle. It is sectional drawing along CC line of FIG. It is an expanded sectional view of the XII part of FIG. It is a top view which shows the conventional workpiece cradle. It is sectional drawing along the DD line of FIG. It is an expanded sectional view of the XV part of FIG.

Explanation of symbols

2 ································································································ 5・ Flatness detector 21 ..... Base body 21a ..... Annular surface 22 ...・ Center convex part 24 ・ ・ ・ ・ ・ ・ ・ ・ Micro projection 24A (64A) (74A) ・ ・ ・ Projection 24a (64a) (74a) ・ ・ ・ Top of the projection (work support) surface)
W ... Work Wa ... Work hole

Claims (10)

A workpiece in which a central convex portion of a flat cylindrical cradle base is fitted into a hole portion of a donut-shaped workpiece during flatness measurement, and an inner peripheral portion of the workpiece is horizontally supported from below by an annular surface surrounding the central convex portion. In the cradle,
A minute protrusion having a sharp point is formed on the annular surface of the cradle base so as to be evenly distributed over the entire area, and a surface formed by the top of the minute protrusion is set as a work support surface. Work cradle.   The work cradle according to claim 1, wherein the minute protrusion is formed integrally with the cradle base.   The workpiece cradle according to claim 1, wherein a top portion of the minute protrusion is configured by a convex curved surface.   The workpiece cradle according to claim 3, wherein the top of the minute protrusion is selected and set from a range of a curvature radius of 0.01 to 1 mm.   The work cradle according to any one of claims 1 to 4, wherein the minute protrusion is configured by an annular ridge that continues in a circumferential direction of the cradle base.   The work cradle according to any one of claims 1 to 4, wherein the minute protrusion is configured by an arc-shaped ridge that is intermittently spaced in a circumferential direction of the cradle base.   The work cradle according to claim 5 or 6, wherein the protrusions are arranged in a plurality of rows in the radial direction of the cradle base.   The work cradle according to any one of claims 1 to 7, wherein a constituent material of the cradle base is a hard synthetic resin.   The work cradle according to claim 8, wherein a constituent material of the cradle base is a polyether / ether / ketone resin. A workpiece in which a central convex portion of a flat cylindrical cradle base is fitted into a hole portion of a donut-shaped workpiece during flatness measurement, and an inner peripheral portion of the workpiece is horizontally supported from below by an annular surface surrounding the central convex portion. A cradle,
A workpiece delivery means for holding the workpiece fed from the previous process and delivering it to the cradle;
Flatness detecting means for detecting the flatness of the workpiece when the workpiece is placed on the cradle;
With
A minute protrusion having a sharp point is formed on the annular surface of the cradle base so as to be evenly distributed over the entire area, and a surface formed by the top of the minute protrusion is set as a work support surface. Workpiece flatness measuring device.

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