Patent Publication Number: US-6663092-B2

Title: Holding apparatus

Description:
This application is a divisional of application Ser. No. 09/809,065, filed on Mar. 16, 2001, now U.S. Pat. No. 6,785,009 the entire contents of which are hereby incorporated by reference and for which priority is claimed under 35 U.S.C. §120; and this application claims priority of Application No. 2000-075271 filed in Japan on Mar. 17, 2000 under 35 U.S.C. §119. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device holding apparatus preferably used for an electric device testing apparatus for testing a variety of electric devices, such as semiconductor integrated circuit element (hereinafter, referred to representatively as ICs). 
     2. Description of the Related Art 
     A testing apparatus for testing a finally produced device, such as an IC chip, is necessary in a producing process of a semiconductor device, etc. As one kind of such testing apparatuses, an electric device testing apparatus for testing an IC chip under applying a thermal stress of a normal temperature, a higher temperature and a lower temperature than a normal temperature is known. It is because IC chips are required to guarantee as a feature thereof to operate well under a normal, high and low temperature. 
     In this kind of an electric device testing apparatus, a test is conducted after a large number of pre-test IC chips loaded on a customer tray are reloaded on a test tray conveyed in the testing apparatus, and tested IC chips are reloaded to customer trays of different categories in accordance with the test result. A device holding apparatus called pick-and-place is used for such a reloading operation of IC chips. 
     There is known a device holding apparatus of the related art using a vacuum suction force wherein a rubber pad is used for absorbing impacts device errors and in a portion contacting an IC chip. 
     However, in a testing apparatus of a type conducting the reloading operation of IC chips in a low temperature chamber, an error in picking up an IC chip was liable to occur due to the rubber pad becoming hard in the low temperature environment. Also, there has been a disadvantage that static electricity charged in an IC chip cannot be removed when the IC chip contact portion was comprised of an insulator like rubber, etc. 
     Accordingly, adoption of a highly conductive metal pad was considered, however, an impact by a metal pad becomes large at the time of contacting an IC chip and the IC chip is liable to be damaged, so a speed of approaching to the IC chip had to be slower to prevent this, and it has been a bottleneck of the reloading operation at a higher speed. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a device holding apparatus excelling in an effect of removing static electricity and an effect of preventing damages on devices. 
     (1) According to a first aspect of the present invention, there is provided a device holding apparatus, comprising a base plate; a hollow pad guard provided on the base plate; a pad pin inserted to the pad guard movably in an axis direction and having a through hole; a pad provided at a tip of the pad pin and having a through hole connected to the through hole of the pad pin; and a bellows pad provided on the base plate, having a through hole connected to the through hole of the pad pin and being elastic in the axis direction; for holding by suction a device by the pad by applying a negative pressure to the through hole of the bellows pad, the through hole of the pad pin and the through hole of the pad. 
     In this device holding apparatus, a pad is approached to a device to contact, and in this state, a negative pressure is applied to a through hole of a bellows pad, a through hole of a pad pin and a through hole of a pad. As a result, the device is sucked by the pad, and at the same time, the bellows pad is shrank due to the negative pressure applied to the through hole and the device is sucked and picked up together with the pad and the pad pin. 
     In the present invention, a force acting on the device at the time of bringing the pad close to the device to contact is only own weights of the pad and the pad pin and an elastic force of the bellows pad. Accordingly, even when the pad approaches at a high speed, the force acting on the device is small and possibility of damaging the device becomes small. Furthermore, since the force acting on the device is small, the pad can be comprised of conductive metal materials and an effect of removing static electricity is large. 
     Note that when releasing the device, the negative pressure having been applied to the through hole of the bellows pad, through hole of the pad pin and through hole of the pad until then is stopped, or a positive pressure is brought to act to the contrary. As a result, the bellows pad having been shrank until then is stretched and the pad and the pad pin are lowered and the device is released. 
     (2) According to a second aspect of the present invention, there is provided a device holding apparatus comprising a base plate; a hollow pad guard provided on the base plate; a pad pin inserted to the pad guard movably in an axis direction and having a through hole; a pad provided at a tip of the pad pin and having a through hole connected to the through hole of the pad pin; and an elastic body provided between the base plate and the pad pin for giving to the pad pin a force in its tip direction; and a sealing body for forming an airtight chamber on a base end side of the pad pin; for holding by suction a device by the pad by applying a negative pressure to the airtight chamber, the through hole of the pad pin and the through hole of the pad. 
     In this device holding apparatus, a pad is brought close to a device to contact, and in this state, a negative pressure is applied to an airtight chamber, a through hole of a pad pin and a through hole of a pad. As a result, the device is sucked by the pad, and at the same time, an elastic body is shrank due to the negative pressure applied to the through hole and the device is sucked and picked up together with the pad and the pad pin. 
     In the present invention, since the pad and the pad pin are provided on a base plate via the elastic body, it is possible to surely hold a device by suction without using a rubber pad and it becomes particularly suitable to a use in a low temperature environment. 
     Also, a force acting on the device at the time of bringing the pad close to the device to contact is only own weights of the pad and the pad pin and a reacting force of the elastic body. Accordingly, by suitably adjusting an elasticity coefficient of the elastic body, the force to be acted on the device is small even if the pad approaches at a high speed, and the possibility of damaging the device becomes less. Furthermore, since the force acting on the device is small as such, the pad can be comprised of conductive metal materials and an effect of removing static electricity is large. 
     Note that when releasing the devices, the negative pressure having been applied to the airtight chamber, through hole of the pad pin and through hole of the pad until then is stopped, or a positive pressure is brought to act to the contrary. As a result, the elastic body having been shrank until then is stretched and the pad and the pad pin were lowered and the device is released. 
     (3) It is not particularly limited in the above invention, but it is preferable that a tip of the pad is more protruding than that of the pad guard when the negative pressure is not applied. 
     Also, it is not particularly limited in the above invention, but it is preferable that the pad, pad pin and base plate are comprised of a conductive material. 
     Alternately, instead of this, it is more preferable that the pad guard is comprised of a conductive material and the device contacts the tip of the pad guard when the negative pressure is applied. 
     It is not particularly limited in the above invention, but the pad pin preferably comprises a rotation stop mechanism. An angle of a held device is aligned by the pad pin because of the provision of the rotation stop mechanism to it. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be explained in more detail below with reference to the attached drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a disassembled perspective view of a device holding apparatus according to an embodiment of the present invention; 
     FIG. 2 is a perspective view from below of the device holding apparatus shown in FIG. 1; 
     FIG. 3 is a sectional view for explaining an operation of the device holding apparatus shown in FIG. 1; 
     FIG. 4 is a sectional view for explaining an operation of the device holding apparatus shown in FIG. 1; 
     FIG. 5 is a sectional view of another embodiment of a device holding apparatus of the present invention; and 
     FIG. 6 is a sectional view for explaining an operation of the device holding apparatus shown in FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     FIG. 1 is a disassembled perspective view of a device holding apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view from below of the device holding apparatus shown in FIG. 1, and FIGS. 3 and 4 are sectional views for explaining an operation of the device holding apparatus shown in FIG.  1 . 
     A device holding apparatus  1  of the present embodiment comprises a base plate  11 , a hollow pad guard  12  provided on the base plate  11 , a pad pin  13  having a through hole  131  inserted to the pad guard  12  movable in the axis direction, a pad  14  having a through hole  141  connected to the through hole  131  of the pad pin  13  and a bellows pad  15  provided on the base plate  11 , having a through hole  151  connected to the through hole  131  of the pad pin  13 , and stretchable in the axis direction. 
     The base plate  11  is mounted on an XYZ-axis drive mechanism outside the drawing and the entire base plate  11  is movable about an X-axis, Y-axis and Z-axis of an electric device testing apparatus, etc. The base plate  11  is provided with an alignment pin  111  for aligning to a tray, etc. loaded with an IC chip  2  to be held and a push pin  112 . 
     The pad guard  12  is fixed on a lower surface of the base plate  11  with a screw, etc. and a pad pin  13  is inserted therein as shown in FIG. 3 so that the pad pin  13  is movable up and down only in the Z-axis direction. 
     The pad pin  13  is formed a through hole  131  inside and the above pad guard  12  is inserted thereto. A not circle flange  132  (a long circle in the present embodiment) is formed at an upper end of the pad pin  13 , and by fitting the long circle flange  132  in a also long circle through hole  113  formed on the base plate  11 , the pad pin  13  is unable to rotate about the Z-axis direction. Note that the pad pin  13  is movable in the Z-axis direction about the pad guard  12  and base plate  11  as shown in FIG.  3 . 
     A pad  14  contacting the IC chip  2  is airtightly fit in at the tip of the pad pin  13  and a through hole  141  is formed inside. The pad  14  can be suitably changed for use in accordance with a size and shape of the IC chip to be held. 
     On the other hand, a block  16  for supporting the bellows pad  15  is fixed on the upper surface of the base plate  11  and an upper end of the bellows pad  15  is fixed by using a pin  161 . The block  16  is formed a through hole  162  connecting to a vacuum generation apparatus (negative pressure generation apparatus) outside the drawing, also the bellows pad  15  is formed a through hole  151 . The through hole  162  of the block  16 , the through hole  151  of the bellows pad  15 , the through hole  131  of the above pad pin  13  and the through hole  141  of the pad  14  are connected in an airtight state. 
     The bellows pad  15  is comprised of an elastic material, such as rubber, and its bellows portion is elastic. The lower end of the bellows portion is provided so as to contact the flange  132  of the pad pin  13 . 
     Note that on the junction face of the lower surface of the block  16  and an upper surface of the base plate  11 , a diameter (width) of an concave portion  163  of the block  16  is set smaller than the diameter of the through hole  113  of the base plate  11 . As a result, even if the pad pin  13  moves up, an upper limit is decided by the flange  132  contacting the pad pin  13 . Namely, the block  16  has a stopper function of the pad pin  13 . 
     Also, in the present embodiment, the pad  14 , pad pin  13 , pad guard  12  and base plate  11  are comprised of a highly conductive metal material and static electricity charged in the IC chip is released to the ground via the pad  14 , pad pin  13 , pad guard  12  and base plate  11 . 
     An operation will be explained next. 
     When holding an IC chip, the base plate  11  is first moved to right above the IC chip  2  loaded on the tray  3 , etc. and then lowered until the pad  14  touches the IC chip  2 . 
     FIG. 3 shows the state, where a force acting on the IC chip  2  at this time is only own weights of the pad  14  and the pad pin  13  and a reacting force of an elastic force of the bellows pad  15 . Accordingly, if the pad  14  collides with the IC chip  2  at the time of lowering the base plate  11  at a high speed, a force to be acted on the IC chip  2  is small and likeliness to be damaged is small. Also, since the force to be acted on the IC chip  2  is small as such, the pad  14  can be comprised of a conductive metal material, etc. as explained above. As a result, static electricity charged on the IC chip  2  can be released to the ground via the pad  14 , pad pin  13 , pad guard  12  and base plate  11 , so that it is possible to prevent the IC chip from being damaged by the static electricity. 
     As shown in FIG. 3, the pad  14  is brought to contact the IC chip  2 , the vacuum drawing is performed in this state, and a negative pressure is applied to the through hole  162  of the block  16 , the through hole  151  of the bellows pad  15 , the through hole  131  of the pad pin  13  and the through hole  141  of the pad  14 . As a result, the IC chip adheres by suction to the pad  14 . At the same time, the negative pressure applied to the through holes  141 ,  131 ,  151  and  162  shrinks a bellows portion of the bellows pad  15  as shown in FIG. 4, and the IC chip  2  together with the pad  14  and the pad pin  13  is picked up by suction. Note that the bellows pad  15  continues to shrink until the flange  132  of the pad pin  13  touches the lower surface of the block  16 . 
     As shown in FIG. 4, after the IC chip  2  is held, the base plate  11  is elevated to be moved to a desired position. 
     It is sufficient to conduct an inversed operation to release the held IC chip  2 . Namely, the base plate  11  is moved to right above a desired tray  3  and lowered until the pad  14  holding the IC chip  2  comes to a slightly upper position of the desired position of the tray  3 . The vacuum drawing is stopped in this state and the negative pressure having been applied to the through hole  162  of the block  16 , the through hole  151  of the bellows pad  15 , the through hole  131  of the pad pin  13  and the through hole  141  of the pad  14  is released. At this time, a positive pressure may be applied for improved releasing of the IC chip  2 . Consequently, the bellows pad  15  having been shrank until then stretches due to its own elasticity, the pad  14  and the pad pin  13  are pressed downward as shown in FIG. 3, and the IC chip  2  touches the tray  3  and is released there. 
     Second Embodiment 
     FIG. 5 is a sectional view of another embodiment of a device holding apparatus of the present invention and FIG. 6 is a sectional view for explaining an operation of the device holding apparatus. 
     The device holding apparatus  1  of the present embodiment uses a spring  17  instead of the bellows pad  15  comparing with the above first embodiment. 
     Namely, there comprises a base plate  11 , a hollow pad guard  12  provided on the base plate  11 , a pad pin  13  having a through hole  131  inserted to the pad guard  12  movably in the axis direction, a pad  14  having a through hole  141  connected to the through hole  131  of the pad pin  13  attached to a tip of the pad pin  13 , a pad holder  18  provided to surround the pad pin  13  and the pad  14 , a spring  17  (an elastic body of the present invention) for giving a force to the pad pin  13  in the direction to its tip, and a packing  20  (a sealing body of the present invention) for forming an airtight chamber  19  on the base end side of the pad pin  13 . 
     Here, the spring  17  is provided between the spring holder  21  provided at the base end of the pad pin  13  and the block  22 . Also, the packing  20  is held at its outer diameter by being sandwiched between the block  22  and the block  23  and held at its inner diameter being sandwiched between the pad pin  13  and the spring holder  21  via a retainer  24 . The airtight chamber  19  is to be formed between the through hole  131  of the pad pin  13  and the through hole  251  of the block  25  due to the existence of the packing  20 . 
     In the present embodiment, the pad  14 , pad pin  13 , pad guard  12  and base plate  11  are comprised of a highly conductive metal material and static electricity charged on an IC chip is released to the ground via the pad  14 , pad pin  13 , pad guard  12  and base plate  11 . 
     An operation will be explained next. 
     When holding an IC chip, the base plate  11  is first moved to right above the IC chip  2  loaded on the tray  3 , etc. and then lowered until the pad  14  touches the IC chip  2 . 
     FIG. 5 shows the above state. In the device holding apparatus  1  of the present embodiment, since the spring  17  gives to the pad  14  movability in the Z-axis direction without using a rubber material, etc. which becomes hard in a low temperature environment, etc., there is no possibility of a positioning error caused by shrink of such a rubber material and the IC chip  2  can be precisely held. 
     Also, a force acting on the IC chip  2  in the state shown in FIG. 5 is only own weights of the pad  14  and the pad pin  13  and an elastic force of the spring  17 . Accordingly, when an elasticity coefficient of the spring  17  is adjusted in accordance with need, even if the pad  14  collides with the IC chip  2  at the time of lowering the base plate  11  at a high speed, a force acting on the IC chip  2  is small and the possibility of damaging the IC chip  2  is small. Also, since the force acting on the IC chip  2  is small as such, the pad  14  can be comprised of a conductive metal material as explained above. As a result, static electricity charged on the IC chip  2  can be released to the ground via the pad  14 , pad pin  13 , pad guard  12  and base plate  11 , so that it is possible to prevent the IC chip from being damaged by static electricity. 
     As shown in FIG. 5, the pad  14  is brought to contact the IC chip  2 , the vacuum drawing is performed in this state, and a negative pressure is applied to the through hole  251  of the block  25 , the airtight chamber  19 , the through hole  131  of the pad pin  13  and the through hole  141  of the pad  14 . As a result, the IC chip  2  adheres by suction to the pad  14 . At the same time, the negative pressure applied to the through holes  141 ,  131 , airtight chamber  19  and through hole  251  shrinks the spring  17  as shown in FIG. 6, and the IC chip  2  together with the pad  14  and the pad pin  13  is picked up by suction. Note that the spring  17  continues to shrink until the upper end of the spring holder  21  touches an inner surface of the block  22 . 
     As shown in FIG. 6, after the IC chip  2  is held, the base plate  11  is elevated to be moved to a desired position. 
     It is sufficient to conduct an inversed operation to release the held IC chip  2 . Namely, the base plate  11  is moved to right above a desired tray  3  and lowered until the pad  14  holding the IC chip  2  comes to a slightly upper position of the desired position of the tray  3 . The vacuum drawing is stopped in this state and the negative pressure having been applied to the through hole  251  of the block  25 , the airtight chamber  19 , the through hole  131  of the pad pin  13  and the through hole  141  of the pad  14  is released. At this time, a positive pressure may be applied for improved releasing of the IC chip  2 . Consequently, the spring  17  having been shrank until then stretches due to its own elasticity, the pad  14  and the pad pin  13  are pressed downwardly as shown in FIG. 5, and the IC chip  2  touches the tray  3  and is released there. 
     Note that the embodiments explained above were described to facilitate the understanding of the present invention and not to limit the present invention. Accordingly, elements disclosed in the above embodiments include all design modifications and equivalents belonging to the technical field of the present invention.