EP0967048A1

EP0967048A1 - Two-sided flattening apparatus

Info

Publication number: EP0967048A1
Application number: EP99110960A
Authority: EP
Inventors: Shiro Furusawa; Yoshihiro Nakajyo
Original assignee: SpeedFam Co Ltd
Current assignee: SpeedFam Co Ltd
Priority date: 1998-06-22
Filing date: 1999-06-08
Publication date: 1999-12-29
Also published as: JP2000006005A

Abstract

A two-sided flattening apparatus configured to be able to continuously change the pressing force of an upper platen to the workpiece and thereby able to prevent damage to the workpiece at the time of contact and able to set the pressing force of the upper platen on the workpiece to a desired value, provided with a lower platen (1), an upper platen (2), and an elevator mechanism (3). A main elevator (6) of the elevator mechanism is formed by a cylinder (60), while a sub elevator (5) of the elevator mechanism is formed by air bags (70), hoses (71), and an air pump (72). The air bags (70) are connected to a connecting meter from the upper platen (2). By making the air bags (70) expand to make the piston rods (62) of the cylinders (60) contract, the upper platen (2) is made to descend to a position in close proximity to the workpiece (w). Suitably thereafter, the air bags (70) are made to contract to make the upper platen (2) softly contact the workpiece (w). The air bags (70) are made to further contract to make the pressing force of the upper platen (2) on the workpiece (w) continuously increase.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a two-sided flattening apparatus capable of finely adjusting the pressing force of an upper platen applied to a workpiece by a sub elevator of an elevator mechanism.

2. Description of the Related Art

FIG. 9 is a sectional view of a two-sided flattening apparatus according to the related art.
As shown in FIG. 9, the two-sided flattening apparatus makes a carrier 110 engaged with a sun gear 101 and an internal gear 102 rotate and revolve by the rotation of the sun gear 101 and makes the lower platen 100 and the upper platen 120 rotate opposite from each other so as to simultaneously polish the two sides of the workpiece W.
In such a two-sided flattening apparatus, an elevator mechanism 200 is provided for making the upper platen 120 rise or descend.
This elevator mechanism 200 is comprised of a large sized main cylinder 201 for simply making the heavy upper platen 120 rise or descend and a small sized sub cylinder 202 for fine adjustment of the pressing force.
Due to this, it is possible to make the heavy upper platen 120 rise and descend by the large horsepower main cylinder 201. Further, at the time of descent of the upper platen 120, the upper platen 120 is made to descend to a position directly above and in close proximity to the workpiece W. Suitably thereafter, the small horsepower sub cylinder 202 is used to bring the upper platen 120 into soft contact with the top of the workpiece W and the pressing force of the upper platen 120 on the workpiece W is increased a little at a time to the desired pressure by the sub cylinder 202.
In the above two-sided flattening apparatus of the related art, however, there were the following problems:
The sub cylinder 202, as shown in FIG. 9, is structured with a piston 204 fit air-tightly into a cylinder body 203. By changing the pressure difference inside an upper chamber 205 and lower chamber 206 defined by the piston 204, the upper platen 120 suspended from the piston rod 207 is made to gradually descend or the pressure on the upper platen 120 is made to gradually increase.
The sub cylinder 202, however, is structured with the piston 204 in facial contact with the inside wall of the cylinder body 203, so due to variations in the sliding friction etc., the piston 204 cannot move finely in accordance with the continuous changes in the pressure difference in the upper chamber 205 and the lower chamber 206.
Therefore, at the time of contact of the upper platen 120 on the workpiece W, the weight of the upper platen 120 may be rapidly applied to the workpiece W and may damage the workpiece W. Further, it is not possible to continuously change the pressing force applied by the upper platen 120 on the workpiece W after contact and not possible to press the workpiece W by a desired pressure. As a result, the problem arises of a different polishing rate of the workpiece W for each batch.

SUMMARY OF THE INVENTION

The present invention was made to solve the above problems and has as its object to provide a two-sided flattening apparatus configured to be able to substantially continuously change the pressing force of the upper platen on the workpiece so as to prevent damage to the workpiece at the time of contact and set the pressing force of the upper platen on the workpiece to a desired value.
To achieve the above object, according to the aspect of the invention, there is provided a two-sided flattening apparatus provided with a rotatable lower platen, an upper platen arranged elevatably above the lower platen, and an elevator mechanism for making the upper platen rise and descend with respect to the lower platen, the elevator mechanism comprising: a sub elevator for increasing, decreasing, heating or cooling a fluid inside a bag member having one end connected to a top part of the upper platen to make the bag member expand or contract; and a main elevator for making a piston rod disposed in a cylinder and connected to another end of the bag member rise or descend by adjustment of the pressure inside a cylinder.
Due to this configuration, if the main elevator of the elevator mechanism is used to make the piston rod connected to the other end of the bag member of the sub elevator move up and down by the adjustment of the pressure in the cylinder, the upper platen rises or descends together with the sub elevator. Further, if the sub elevator of the elevator mechanism is used to increase, decrease, heat or cool the fluid in the bag member connected to the top part of the upper platen to make the bag member expand or contract, the upper platen rises and falls continuously in accordance with the expansion or contraction of the bag member.
The sub elevator of the elevator mechanism may make the bag member expand or contract by increasing, decreasing, heating or cooling the fluid in the bag member. As one example, according to the aspect of the invention, the sub elevator of the elevator mechanism comprises: an air bag serving as the bag member having one end connected to a top part of the upper platen and having another end connected to a piston rod of the main elevator; a hose connected to the air bag; and an air pump for pumping air into and out of the air bag through the hose.
Due to this configuration, if the air pump of the sub elevator is used to pump air into and out from the air bag having one end connected to the top part of the upper platen and having another end connected to the piston rod of the main elevator, the air bag expands or contract and the upper platen rises or descends continuously in accordance with the expansion or contraction of the air bag.
Further, as another example of the sub elevator, according to the aspect of the invention, the sub elevator of the elevator mechanism comprises: an air bag serving as the bag member having one end connected to a top part of the upper platen and having another end connected to a piston rod of the main elevator; and a heating/cooling apparatus capable of heating and cooling the air in the air bag.
Due to this configuration, if the heating/cooling apparatus is used to heat or cool the air in the air bag, the air bag expands or contracts and the upper platen continuously rises or descends in accordance with the expansion or contraction of the air bag.
Further, it is also possible to adopt a structure making the upper platen descend by making the bag member of the sub elevator contract. Therefore, according to an aspect of the invention, the upper platen is provided with a connecting member extending sideways from the top part; the top end of the bag member of the sub elevator is connected to the connecting member; and the piston rod of the main elevator is connected to the bottom end of the bag member.
Due to this configuration, if the piston rod of the main elevator moves up or down, the connecting member connected to the top end of the bag member of the sub elevator moves up and down together with the bag member and the platen rises or descends linked with the connecting member. When the bag member shrinks, the platen descends continuously.
Further, it is also possible to adopt a structure of making the upper platen descend by making the bag member of the sub elevator expand. Therefore, according to an aspect of the invention, the bottom end of the bag member of the sub elevator is connected to the top part of the upper platen and the top end of the bag member is connected to the piston rod of the main elevator.
Due to this configuration, if the piston rod of the main elevator connected to the top end of the bag member of the sub elevator moves up or down, the upper platen connected to the bottom end of the bag member rises or descends together with the bag member. If the bag member expands, the platen descends continuously.
The two-sided flattening apparatus of the present invention may be a two-sided lapping apparatus or a two-sided flattening apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of presently preferred embodiments of the invention taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a partially cut away front view of a two-sided flattening apparatus according to a first embodiment of the present invention;
FIG. 2 is a sectional view along the line A-A of FIG. 1;
FIG. 3 is a perspective view of the structure of a bearing member;
FIG. 4 is a sectional view of the state of assembly of a bearing member on to a rail;
FIG. 5 is a schematic front view of the state of rise of the upper platen;
FIG. 6 is a schematic front view of the state of the upper platen made to descend to a position directly above and in close proximity to the workpiece;
FIG. 7 is a schematic front view of the state of the upper platen in contact with the workpiece;
FIG. 8 is a partially cutaway front view of a two-sided flattening apparatus according to a second embodiment of the present invention; and
FIG. 9 is a sectional view of the two-sided flattening apparatus according to an example of the related art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will be explained below with reference to the drawings.

(First Embodiment)

FIG. 1 is a partially cut away front view of a two-sided flattening apparatus according to a first embodiment of the present invention.
The two-sided flattening apparatus is provided with a lower platen 1, an upper platen 2, and an elevator mechanism 3 for making the upper platen 2 rise or descend with respect to the lower platen 1.
The lower platen 1 is a donut-shaped disk member arranged concentrically at the outside of the sun gear 10 attached to the top end of the shaft 10a rotating by a not shown motor and is driven to rotate by a not shown motor. An internal gear 11 is arranged concentrically with the lower platen 1 at the outside of the lower platen 1 and is rotated by a not shown motor.
A carrier 12 having a hole 12a for holding a workpiece W is placed on this lower platen 1 and is engaged with a sun gear 10 and internal gear 11.
Note that reference numeral 10b indicates a driver attached on the sun gear 10. A longitudinal groove 10c is cut into the periphery of the driver 10b.
On the other hand, the upper platen 2 is arranged above the lower platen 1. At the center of the bottom surface of the upper platen 2 is provided a recess 20 in which the driver 10b fits. In the recess 20 is attached a hook 21 engageable with the longitudinal groove 10 of the driver 10b.
Above the upper platen 2 is attached a connecting member 4 extending to the elevator mechanism 3 side from above the upper platen 2. Specifically, a shaft 22 of the upper platen 2 is inserted through a support member 40 fixed to the connecting member 4. A bearing 41 is attached between the support member 40 and the shaft 22.
With the lower platen 1 and the upper platen 2 being configured this way, if the upper platen 2 is made to descend to the lower platen 1 side to make the upper platen 2 contact with the workpiece W, the longitudinal groove 10c of the driver 10b is made to engage with the hook 21 in the recess 20, and in that state the lower platen 1, the sun gear 10 and the internal gear 11 are made to rotate, the carrier 12 will revolve around the sun gear 10 while rotating and the two sides of the workpiece W will be polished by the rotating lower platen 1 and upper platen 2.
The elevator mechanism 3 makes the upper platen 2 rise or descend by making the connecting member 4 move up or down and is provided with a main elevator 6 and a sub elevator 7 fixed to the base 5.
The main elevator 6 is comprised of three large sized cylinders 60 bolted to the base 5. The front end of the piston rod 61 of each cylinder 60 is connected to the movable plate 63. Note that the three cylinders 60, as shown by the broken lines of FIG. 2, are arranged point symmetrically around the male screw member 67 of an after-mentioned motor 65.
At the side part of the movable plate 63, as shown in FIG. 1, is attached a ball bearing 64 fit on a rail 50 provided projecting from the base 5. The movable plate 63 moves up and down guided by the rail 50.
At the bottom side of the center portion of the movable plate 63 is provided with a motor 65 for making the movable plate 63 move up or down linked with the cylinder 60. Specifically, the motor 65 is bolted to the bottom side of the base 5 and has a male screw member 67 connected to the front end of its shaft 66. The male screw member 67 is screwed into the female screw member 68 attached to the center part of the movable plate 63.
By configuring the main elevator 6 in this way, it is possible to change the air pressure in the cylinder 60 to make the piston 62 move up and down to make the piston rod 61 extend and retract. Further, by driving the motor 65 to make the male screw member 67 rotate either forward or reverse, the female screw member 68 engaged with the male screw member 67 rises or descends on the male screw member 67. That is, due to the cooperative action of the three cylinders 60 and the motor 65, it is possible to make the movable plate 63 move up or down.
The sub elevator 7 is comprised of three air bags 70 placed on and fixed to the movable plate 63, three hoses 71 connected to the air bags 70, and an air pump 72 pumping air into and out of the air bags 70 through the hoses 71. The three air bags 70, as shown by the solid lines in FIG. 2, are arranged point symmetrically directly above the three cylinders 60.
Above the air bags 70, as shown in FIG. 1, are attached shafts 73. The top parts of the air bags 70 are connected through these shafts 73 to the connecting member 4.
At the approximate center part of the connecting member 4 and the right end in FIG. 1 are suspended support members 42 and 43. A pair of bearing members 44 are attached to the support members 42 and 43.
These bearing members 44 are attached vertically movably to the frame member 51 provided projecting from the base 5. Specifically, the frame member 51 is formed by a plurality of column members 52 and a plate member 53 attached on these column members 52. The bearing members 44 are attached to rails 54 attached to the side parts of the column members 52.
FIG. 3 is a perspective view of the structure of a bearing member 44; while FIG. 4 is a sectional view of the state of assembly of a bearing member 44 on to a rail 54.
As shown in FIG. 3, each of the bearing members 44 form U-sectional shapes. Ball holders 44b are formed in the two inner side surfaces 44a. A plurality of balls 44c are accommodated in the ball holders 44b. On the other hand, the two side surfaces of the rails 54, as shown in FIG. 4, have V-shaped grooves 54a cut into them in the longitudinal direction. The exposed portions of the balls 44c of the bearing members 44 are made to abut against the grooves 54a.
By configuring the sub elevator 7 in this way, by making the three air bags 70 expand or contract by the air pump 72, the connecting member 4 moves up or down by exactly the distance corresponding to the amount of expansion or amount of contraction of the air bag 70, the bearing members 44 slide along the rails 54, and the upper platen 2 rises or descends with respect to the lower platen 1.
Next, an explanation will be made of the operation of the two-sided flattening apparatus of this embodiment.
First, as shown in FIG. 5, the air pump 72 is used to supply air through the hoses 71 to the three air bags 70 to make the three air bags sufficiently and equally expand. The three cylinders 60 of the main elevator 6 are driven to make the piston rods 61 extend equally upward and the motor 65 is driven so that the female screw member 68 of the movable plate 63 rises along the male screw member 67.
By performing this operation for a predetermined time, the upper platen 2 rises to separate from the lower platen 1, then a not shown loader is used to transfer the workpiece W to the lower platen 1 and place it in a hole 12a in the carrier 12 (see FIG. 1).
After the workpiece W finishes being placed in the carrier 12, the cylinders 60 are driven in reverse to make the piston rods 61 retract and the motor 65 is driven in reverse so that the female screw member 68 of the movable plate 63 descends along the male screw member 67.
Due to this, the upper platen 2 descends toward the lower platen 1, so, as shown in FIG. 6, when the upper plate 2 descends to a position directly above and in close proximity to the workpiece W, the cylinder 60 and the motor 65 stop being driven and the upper platen 2 is maintained at the position directly above and in close proximity to the workpiece W.
In this state, as shown in FIG. 7, the air pump 72 is used to draw the air out of the air bags 70 to make the air bags 70 contract, whereupon the upper platen 2 gradually descends toward the workpiece W and contacts the surface of the workpiece W.
In the two-sided flattening apparatus of the related art shown in FIG. 9, the above contact work is performed by the sub cylinder 202, but due to the variation in the sliding frictional resistance between the piston 204 and the cylinder body 203, the piston 204 does not move in accordance with the change in pressure in the cylinder body 203 and sometimes the upper platen 120 falls rapidly on the workpiece W.
In the two-sided flattening apparatus of this embodiment, however, there is no frictional resistance due to the contraction of the air bags 70. The problem becomes merely the friction between the balls 44c of the bearing members 44 and the rails 54. When the bearing members 44 descend together with the support members 42 and 43, the balls 44c roll on the side surfaces of the rails 54. Therefore, there is almost no frictional resistance between the balls 44c and the rails 54.
Therefore, the upper platen 2 descends continuously in accordance with the amount of contraction of the air bags 70. By making the rate of contraction of the air bags 70 smaller, it is possible to make the upper platen 2 come into soft contact with the surface of the workpiece W.
Further, by making the air bags 70 further contract gradually after the upper platen 2 comes into contact with the workpiece W, the pressing force of the upper platen 2 on the workpiece W increases continuously, so the air pump 72 is stopped when the desired pressing force is reached.
By driving the lower platen 1, sun gear 10, and internal gear 11 in this state, the two sides of the workpiece W held in the carrier 12 rotating and revolving around the sun gear 10 are polished by the desired polishing rate by the rotating lower platen 1 and upper platen 2.
In this way, according to the two-sided flattening apparatus of this embodiment, since it is possible to make the upper platen 2 softly contact the workpiece W, it is possible to prevent damage to the workpiece W during the contact work. Further, it is possible to achieve a high precision polishing rate, so it is possible to provide high quality workpieces W.

(Second Embodiment)

FIG. 8 is a partially cutaway front view of a two-sided flattening apparatus according to a second embodiment of the present invention.
The two-sided flattening apparatus of this embodiment differs from the first embodiment in the point of arranging the elevator mechanism 3 above the lower platen 1.
Specifically, as shown in FIG. 8, the elevator mechanism 3 as a whole is attached above the lower platen 1 in an upside-down state. Further, the connecting member 4' is connected to the lower ends of the three air bags 70 through the shafts 73. Therefore, the top ends of the air bags 70 are connected to the lower ends of the piston rods 61 of the cylinders 60 through the movable plate 63. The upper platen 2 is connected rotatably to the support mechanism 40' attached to the center portion of the connecting member 4'. That is, the shaft 22 is inserted through the support member 40' and a bearing 41 is attached between the shaft 22 and the support member 40'.
Due to this configuration, by making the main elevator 6 and the sub elevator 7 operate in reverse from the first embodiment, it is possible to perform the same operation as the rising and descending operation of the upper platen 2 in the first embodiment.
That is, when making the upper platen 2 rise so as to separate from the lower platen 1, the air pump 72 is used to drawn the air out from the three air bags 70 to make the air bags 70 contract. Further, the three cylinders 60 of the main elevator 6 are drive in reverse to retract the piston rods 61 equally and the motor 65 is driven in reverse so that the female screw member 68 of the movable plate 63 rises along the male screw member 67.
Further, when making the upper platen 2 descend to a position directly above and in close proximity to the workpiece W, the cylinders 60 are driven to make the piston rods 61 extend and the motor 65 is driven so that the female screw member 68 of the movable plate 63 descends along the male screw member 67.
Further, when making the upper platen 2 softly contact the surface of the workpiece W, the air pump 72 is used to supply air into the air bags 70 to make the air bags 70 gradually expand. Further, by making the air bags 70 gradually expand, it is possible to make the pressing force of the upper platen 2 on the workpiece W a desired pressing force.
The rest of the configuration, mode of operation, and advantageous effects are similar to those of the first embodiment, so descriptions of these are omitted.
Note that the present invention is not limited to the above embodiments. Various modifications and change may be made within the scope of the gist of the invention.
For example, in the above embodiments, a motor 65 was provided, but it is possible to leave this out and make the upper platen 2 rise or descend by just the three cylinders 60.
Further, three cylinders 60 and air bags 70 were provided, but the invention is not limited to this number.
Further, in the above embodiments, the invention was configured to make the three air bags 70 expand and contract by pumping in or out air, but the invention may also be configured to make the air bags 70 expand and contract by filling air into the air bags 70 in advance and then heating or cooling the air in the air bags 70 by a heating/cooling apparatus.
As explained in detail above, according to the two-sided flattening apparatus of the present invention, the main elevator of the elevator mechanism is used to make the upper platen descend to close to the workpiece on the top of the lower platen, then the sub elevator of the elevator mechanism is used to make the upper platen continuously descend toward the workpiece. Therefore, there are the superior effects that it is possible to bring even a heavy upper platen into soft contact with a workpiece and possible to prevent damage to the workpiece at the time of contact with the upper platen. Further, after contact, it is possible to use the sub elevator of the elevator mechanism to continuously increase the pressing force of the upper platen on the workpiece, so it is possible to set the pressing force on the workpiece to a desired value and as a result possible to obtain a high precision polishing rate in different batches.

Claims

A two-sided flattening apparatus provided with a rotatable lower platen, an upper platen arranged elevatably above the lower platen, and an elevator mechanism for making the upper platen rise and descend with respect to the lower platen, said elevator mechanism comprising:

a sub elevator for increasing, decreasing, heating or cooling a fluid inside a bag member having one end connected to a top part of said upper platen to make the bag member expand or contract; and

a main elevator for making a piston rod disposed in a cylinder and connected to another end of said bag member rise or descend by adjustment of the pressure inside said cylinder.
A two-sided flattening apparatus as set forth in claim 1, wherein said sub elevator of said elevator mechanism comprising:

an air bag serving as said bag member having one end connected to a top part of said upper platen and having another end connected to said piston rod of said main elevator;

a hose connected to said air bag; and

an air pump for pumping air into and out of said air bag through said hose.
A two-sided flattening apparatus as set forth in claim 1, wherein said sub elevator of the elevator mechanism comprising:

an air bag serving as said bag member having one end connected to a top part of said upper platen and having another end connected to a piston rod of said main elevator; and

heating/cooling apparatus capable of heating and cooling the air in said air bag.
A two-sided flattening apparatus as set forth in claim 1, wherein

said upper platen is provided with a connecting member extending sideways from the top part;

the top end of said bag member of said sub elevator is connected to said connecting member; and

said piston rod of said main elevator is connected to the bottom end of said bag member.
A two-sided flattening apparatus as set forth in claim 1, wherein

the bottom end of said bag member of said sub elevator is connected to the top part of said upper platen; and

the top end of said bag member is connected to said piston rod of said main elevator.