US20020153735A1

US20020153735A1 - Variable-pitch pick and place device

Info

Publication number: US20020153735A1
Application number: US10/170,250
Authority: US
Inventors: Lothar Kress
Original assignee: Micron Technology Inc
Current assignee: Micron Technology Inc
Priority date: 2000-03-03
Filing date: 2002-06-11
Publication date: 2002-10-24
Also published as: US6439631B1

Abstract

Improved variable-pitch pick and place devices may include one or more improvements such as a mechanical linkage such as pantograph linkage, the linkage itself linked to a plurality of device-gripping mechanisms arranged in a row so as to keep uniform, though variable, spacing between the device-gripping mechanisms, with the number of such mechanisms being increased relative to the number of parts in the linkage for reduced tolerance stack-up and improved positioning accuracy. The horizontal position of the linkage may be fixed at a position not at an end thereof, and desirably within the middle third or at the middle thereof. The linkage may be controlled at three points. These point may include a vertically flexible but horizontally fixed link to a supporting structure at the middle of the pantograph, a link at one end of the pantograph to one side of an endless loop of timing belt, and a link at the other end of the pantograph to the other side of the endless loop of timing belt. The links to the timing belt at the ends of the pantograph may be made via two end-most device-gripping mechanisms. The position of the timing belt may be controlled by a servomotor with a position encoder, the servomotor controlled by a controller such as a computer. The device-gripping mechanisms may include a vacuum tip grounded and supplied with vacuum by an electrically-conductive vacuum tube.

Description

FIELD

This invention relates to fabrication and testing of integrated circuit devices, and particularly to pick and place devices for assisting in processing and testing of integrated circuit devices.

BACKGROUND

Modem electronics devices, such as integrated circuits or semiconductor “chips” are rapidly increasing in performance and functionality, and in production quantity, while simultaneously decreasing in size and unit cost. To increase the productivity and decrease the cost of electronic devices, it is desirable to decrease the time and cost of all operations in the production cycle.

Cost efficiency and productivity of processes performed on individual chips, such as burn-in, various test processes, binning, and the like, require precise, high-throughput handling of many chips. Traditionally, chips were transported in a container such as a magazine—a container typically designed to hold a row of chips placed end-to-end by sliding them one-by-one into one end of the container. Chips were removed from a magazine and separated from one another for processing, and replaced in a magazine after processing, by the force of gravity.

Chip handling systems which utilize the force of gravity to separate and transfer the electronic devices have at least two inherent disadvantages.

First, since modem electronic devices have become smaller and lighter than before, an individual electronic device may not have sufficient weight to be efficiently separated from the others by gravity. This may cause jamming. If such jamming occurs, it is usually necessary to stop the operation of the system to clear the jam, thus causing a serious loss of time and efficiency. Furthermore, the risk of jamming is greatly increased due to the configuration of the new types of electronic devices, such as chips with leads (pins) on all sides of the package, instead of two opposing sides as in the conventional dual in-line package (DIP).

Second, to minimize jamming, the outer surface of the electronic device must be made sufficiently smooth so as to not cause any friction or unwanted engagement with other devices or the magazine. However, this is also impractical since the plastic molded packages of the devices often have some burrs remaining from the production process and it is not generally economically practical to completely eliminate such burrs.

More recently, trays holding arrays of chips have been used for transport and handling of chips instead of magazines. The individual chips occupy individual cells within the array, and are removed from and replaced in the tray by a “pick and place” device. A pick and place device typically employs multiple individual vacuum grippers, arranged in a row, to pick up and to place a row or column of chips. The pitch or spacing between the cells in the array is typically fixed, although the pitch may vary between different tray types. Also, the chips may have to be transported from one tray or other holder, such as a precisor, multi-track chip runway or the like, to another holder having a different pitch. This may occur as part of a processing, testing, or packaging operation or the like.

Some pick and place devices with multiple grippers have grippers positioned at a fixed pitch. The pitch of such devices may match the required pitch of an associated machine or process, or of a tray for such machine or process. However, a fixed-pitch pick and place device may often not match the pitch, of a tray or other type of chip holder, with which it must be used. In particular, where a tray or other chip holder does not match the pitch of a precisor, a multi-track runway, or any other chip holder to which the chips must be transferred, a fixed-pitch pick and place device will be mismatched to at least one of the chip holders. This results in the pick and place device having to pick-up or set-down of a row of chips one at a time rather than simultaneously.

Variable-pitch pick and place devices have been developed, such as the device disclosed in U.S. Pat. No. 5,290,134, to provide the capability of simultaneous pick-up and deposit even where the pitch of one holder may differ from that of another holder. Nevertheless, a need exists for improved variable pitch pick and place devices.

SUMMARY

A variable-pitch pick and place device with increased positioning precision and increased flexibility, with decreased complexity and cost and maintenance requirements, and with provision for electronic and thus easily-programmable pitch control is provided by the various aspects and embodiments of the present invention.

According to one embodiment, a variable-pitch pick and place device includes a plurality of device-gripping mechanisms supported in a horizontal row, the horizontal positions of the mechanisms being electronically controlled so as to maintain uniform, though variable, spacing or pitch between the device-gripping mechanisms. The desired pitch may be set via a look-up table stored in a controller such as a computer. An operator may select a tray type, or a machine or process type or the like, to trigger a look-up operation in the look-up table to obtain a value used to control the pitch. The computer may then use the value from the table to cause the adjustment of the pitch between the grippers to match a desired pitch. A controller or computer may also be used to control the pitch regardless of whether information on the desired pitch and/or the value used to control the grippers is obtained from a look-up table, entered manually, or calculated, or obtained by other means.

According to another embodiment, a variable-pitch pick and place device has a mechanical linkage, such as a scissors or pantograph linkage, itself linked to a plurality of device-gripping mechanisms so as to maintain uniform, though variable, spacing or pitch between the device-gripping mechanisms. The links to the plurality of device-gripping mechanisms are positioned so as to allow an increased number of device-gripping mechanisms to be positioned along the pantograph linkage relative to the number of links in the linkage. This yields improved positioning precision and decreased total number of linkage parts in the device.

According to yet another embodiment, a variable-pitch pick and place device has mechanical linkage such as a scissors or pantograph linkage, itself linked to a plurality of device-gripping mechanisms so as to keep uniform, though variable, spacing between the device-gripping mechanisms, and also linked to a supporting structure, the link between the linkage and the supporting structure not being at an end of the linkage, but desirably being within the middle third and most desirably at the middle of the linkage.

According to another aspect of an embodiment, a variable-pitch pick and place device may have a mechanical linkage, itself linked to a plurality of device-gripping mechanisms so as to keep uniform, though variable, spacing between the device-gripping mechanisms, and the position of the linkage may be controlled through three links to the linkage, one relatively near the middle compared to the other two, and two relatively near the ends, compared to the one.

According to another embodiment, in a device having a mechanical linkage such as a scissors or pantograph linkage for keeping uniform, though variable, spacing between electronic device-gripping mechanisms, the extension and contraction of the linkage is controlled by a timing belt or, if desired, a chain. The belt may be a continuous loop, the loop having two sides defined between a drive pulley or sprocket and an idler pulley. One end of the linkage may be attached to one side of the belt, the other end to the other. The linkage may also be anchored horizontally at the center thereof, such that the linkage is controlled from three points, providing improved position control due to decreased stack-up of mechanical tolerances. A servo or the like may be used to control the motion of the drive pulley. An encoder on the shaft of the servo motor can allow precise electronic control of the pitch of the electronic device gripping mechanisms. Such electronic control lends itself to programmed or otherwise automated pitch changes. As an aspect of the embodiment, the pitch of the grippers may be controlled using a programmed computer.

According to another embodiment, movable portions of device-gripping mechanisms are supplied with both vacuum and electrical ground via a single structure, such as an electrically conductive vacuum tube, eliminating the need for separate grounding wires for every such movable portion.

The invention is directed to these and other new and nonobvoius aspects, both individually and in combination, of improved variable-pitch pick and place apparatuses as disclosed herein. The above and other aspects, features, advantages, and benefits of the present invention will be apparent from the description bellow, which proceeds with reference to following figures:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a pick and place device according to one embodiment of the present invention. [0018]
FIGS. 2 and 3 are perspective views of a gripper mechanism that may be employed in an embodiment of the present invention, [0019]
FIG. 2 with a movable portion retracted, [0020]
FIG. 3 with the movable portion extended. [0021]
FIGS. 4 and 5 are perspective views of certain components, including a scissors or pantograph linkage, useful in an embodiment of the present invention, [0022]
FIG. 4 with the pantograph linkage contracted, [0023]
FIG. 5 with the pantograph linkage extended. [0024]
FIG. 6 is an elevation view of certain components, including a scissors or pantograph and a controller, useful in an embodiment of the present invention. [0025]
FIG. 7 is a schematic plan view of an example application of an embodiment of the present invention.[0026]

DETAILED DESCRIPTION OF EMBODIMENTS

An example embodiment of a pick and [0027] place head 41 for a pick and place device is shown in perspective in FIG. 1, including twelve individual example gripper mechanisms, some of which are indicated by reference character 31. An example embodiment of a single gripper mechanism 31 is shown in detail in the perspective view of FIG. 2 in retracted position, and in FIG. 3 in extended position.
The [0028] head 41 of FIG. 1 comprises a support structure in the form of a frame 2 on which are supported the illustrated twelve gripper mechanisms 31, six on one side and six on the other side of the frame. Each gripper mechanism 31 includes a gripper in the form of a vacuum tip 12 (FIG. 2). The vacuum tips 12 of the gripper mechanisms on each side of the frame 2 extend toward the center of the frame such that the vacuum tips from both sides are aligned together in a single row.
FIGS. 4 and 5 show the six example gripper mechanisms on the back-most side of FIG. 1, but with the [0029] frame 2 and the six gripper mechanisms from the front-most side of FIG. 1 omitted. FIG. 4 shows the back six gripper mechanisms in a retracted position, while FIG. 5 shows an extended position. As alternate embodiments, more or fewer gripper mechanisms may be included and such mechanisms may assume a form other than shown in these figures. Also, more than one row of gripper elements may be provided.
As shown in FIGS. 1 and 2, in the [0030] example gripper mechanisms 31, each gripper mechanism includes anchor block 32 to which a vertical motion or “z-” actuator is attached. One form of such an actuator includes an air cylinder 10 mounted by a bracket 35 (FIGS. 2, 3) to a sub-plate 33 which is coupled to an anchor block 32 (FIG. 1). Air cylinder 10 includes a piston 37 with a piston extension 38. Air ports 34 (FIGS. 2, 3) are in fluid communication with the cylinder 10 to allow delivery of driving air for driving the cylinder 10 in both the upward and downward directions in this embodiment. A fixed flow control valve 36 sets the speed of the downward stroke of the cylinder 10, which aids in preventing damage to electronic devices handled by the gripper mechanisms 31. In another embodiment, valve 36 is adjustable. As an alternative embodiment, the cylinder may also be driven only in one direction, (e.g. downwardly), with a biasing mechanism being used to return the cylinder.
The vertical position of the [0031] piston 37 of the cylinder 10 is transmitted to a vertically movable portion 23 of the gripper mechanism 31. The downward motion of the piston 37 is transmitted via the piston extension 38 to portion 23. A limiting spring 21 serves to limit the downward force applied to the movable portion 23, to aid in preventing damage to electronic devices handled by the gripper mechanism. The movable portion 23 is slidably supported on the sub-plate 33 by a linear bearing 13 for upward and downward movement as the piston is operated.
An example gripper in the form of a vacuum tip [0032] 12 (FIGS. 2, 3) is mounted on the vertically movable portion 23. The vacuum tip 12 is in fluid communication, through a passage in the movable portion 23, with the interior of a hose fitting 22 mounted on movable portion 23. Accordingly, suction may be supplied to fitting 22 via a hose 60 (shown in FIG. 2 in dashed lines) to provide suction at vacuum tip 12. In this example embodiment, the hose 60, the hose fitting 22, the body of the movable portion 23, and the vacuum tip 12 are optionally and desirably formed of electrically conductive material, with the hose connected (at the end not shown but indicated schematically by ground 43) to a grounded structure (not shown), to protect the handled electronic devices from electrical damage from electrostatic discharge, stray currents, or the like. This feature eliminates the need for a grounding wire for each movable portion 23 of each gripper mechanism 31 separate or discrete from the hose 60 by providing both a vacuum and a grounding path with a single element (the vacuum hose). The vacuum hose may be any suitable available conductive tubing, such as anti-static conductive nylon or polyurethane, such as the polyurethane tubing available from SMC Pneumatics, Inc., of Indianapolis, Ind. under the designation TAU. Related components, such as fitting 22 and other fittings, may be of metal or other suitable electrically conductive materials. The tip 12 has a suction cup end formed of a flexible material, such as conductive polyurethane, for example.
In the operation of an individual [0033] example gripper mechanism 31, air is supplied to the cylinder 10 to lower the movable portion 23 such that the gripper 12 approaches an electronic device to be gripped. A common hard stop such as in the form of a stop rail 14 is provided on the frame 2 in the example embodiment of FIG. 1 for each set of six gripper mechanisms, providing a reliable means for limiting the extended position of each movable portion 23 to match the extended positions of the other movable portions 23. A vacuum is supplied to the vacuum fitting 22 to cause the vacuum tip 12 to grip the electronic device. Air is then supplied to the cylinder 10 to retract the piston extension 38 and raise the movable portion 23 with the device to be gripped held by the vacuum tip 12. An individual stop 40 (FIGS. 2, 3) engages the lower ledge of sub-plate 33 and limits the upward travel of the movable portion 23. With the movable portion in the retracted position, the stop rail 14 (FIG. 1) also functions as a crash guard by extending below the lowest portion of the vacuum tip 12 in the retracted position. Optical through-beam sensors, such as optical through-beam sensor 20 (FIG. 1), may be used to detect, by beam interruption, for example, whether all of the movable portions 23 are up, and/or whether any are down, thus providing feedback on the operation of the movable portions 23.
The individual example gripper mechanisms may be operated individually when selective transfer of electronic devices is desired, by selectively supplying the desired air pressure and vacuum to the individual gripper mechanisms. This allows the example embodiment variable pitch pick and place head to perform sorting for testing, binning, and similar operations and to pick up a full load of devices from trays that may have gaps in various rows, with, for example, devices picked up from more than one row of a tray in order to fully load the grippers. [0034]
The individual example gripper mechanisms are supported for movement along the direction of the row of [0035] vacuum tips 12. In the illustrated example, the gripper mechanisms (FIGS. 1 and 4) are supported slidably on a guide rail 9, via a guide block 42 attached to each respective anchor block 32, with one rail 9 for each of the two sets of six gripper mechanisms. The guide block 42 and the guide rail 9 together constitute a form of linear bearing 8, as best shown in FIGS. 4 and 5. The guide rail is an elongated member having a longitudinal axis.
With reference to FIGS. 4, 5 and [0036] 6, even spacing or pitch between the gripper mechanisms is preserved in this example by a linkage desirably arranged in the form of a scissors mechanism or pantograph 44 comprised of rigid beams (some being indicated as 45) linked together to form a series of parallelograms. The parallelograms thus formed are desirably in a plane which may be horizontal or in some other orientation, such as desirably in a vertical plane, as shown in FIGS. 4 and 5. The pantograph 44 may then be disposed within a central slot 46 in the center of the frame 2 of the example embodiment of FIG. 1, allowing the head 41 to be of a narrower width than with a horizontally disposed pantograph. As shown in FIGS. 4 and 5, each beam within the interior portions of the illustrated pantograph is pivotally linked to another beam both at a crossover point, some being indicated at 17, located at the midpoint of each beam and at both upper and lower pivot points (such as indicted at 19 for some of the beams) located at the ends of the beam. The beams at the ends of the pantograph are linked similarly, but are shortened so as to extend only to the crossover point, or in the case of outermost beams 15 and 16, to respective link points 18 a, 18 b (FIGS. 4, 5). Alternative pitch control devices may of course be employed for the gripper elements, such as other linkage mechanisms or a screw-driven positioning block for each gripper mechanism, for example, but a pantograph linkage is generally desirable for overall simplicity and reliability.
In the illustrated pantograph embodiment, the link points [0037] 18 c at which the gripper mechanisms are pivotally attached via pins to the pantograph 44 are located midway between the crossover point 17 and the lower of pivot points 19 on each beam. Link points 18 a, 18 b are ate the same elevation. This location for the link points 18 a, 18 b and 18 c provides twelve of the link points with only five total parallelograms in the pantograph 44 (recall that the front-most set of six gripper mechanisms is not shown in FIGS. 4 and 5). This location for the link points 18 a, 18 b and 18 c provides about twice as many link points for the same number of pantograph beams as compared to the less desirable option in which the link points for the gripper mechanisms are at the midpoints 17. The link positions at link points 18 c provides two gripper link locations for every parallelogram, plus two more link locations at 18 a, 18 b in the respective last parallelograms, as compared to one link location for every parallelogram, plus one more at the last parallelogram. In other words, the number of complete parallelograms in the structure is one less than half the number of gripper link locations, as compared to simply one less than the number of link locations. As this embodiment is merely a desirable example, other link points may also be used, to achieve an equal or even greater increase in the number of link points per parallelogram. Increased link points per parallelogram provide more accurate position control, since fewer links mean that a lower total number of mechanical tolerances influences the total positioning error. Less total parallelogram parts also provides a lower cost, lower maintenance head.
The position of the [0038] pantograph 44 in the direction along the row of vacuum tips 12 relative to the frame 2 is controlled in this example by a ball-bearing supported roller 7 (See FIG. 1), in this case attached to uppermost pivot point 19 or a first point at the center of the pantograph 44. The roller 7 rolls vertically between two roller plates 49 attached to the frame 2 of the example embodiment of FIG. 1. The roller 7 thus serves to locate or fix the position of the first point and thus of the pantograph 44, in the direction along the row of vacuum tips 12, by a link at a position at or near the middle of the pantograph. It is desirable (but not precluded) that this first point or horizontal locating link not be at an extreme end of the pantograph 44 but rather at this center location, or at least within the middle third of the length of the pantograph so that tolerance stack-up is further reduced compared to positioning a horizontal locating link at or near an end of a pantograph linkage. Positioning a horizontal locating link at the midpoint also preserves the midpoint of the row of vacuum tips 12 during adjustment of the pitch of the tips 12. The roller 7 restrains the first point of the linkage against movement a direction along the longitudinal axis of the rail.
FIG. 6 is an elevation view of certain example components related to controlling the extension of the pantograph and the resulting spacing between adjacent ones of the [0039] vacuum tips 12, including the gripper mechanisms 31, the guide rails 9 (only one visible), and the pantograph 44 without the frame 2, but including a motor housing 3, a timing belt 4, and an idler pulley 11. The timing belt 4 constitutes one form of a ten side force transmitting member and extends in a loop around a drive pulley 52, past the gripper mechanisms 31, and around the idler pulley 11. The belt 4 may be a continuous belt. Desirably the belt may be an open ended loop for easier assembly and replacement. In this case, for example, the two ends of the belt may meet in one of the outermost gripper mechanisms 5, 6 and are held in place, for example, by a clamp. Only the frontward half of this loop 4 is visible in FIG. 6. Tension on the loop of the timing belt 4 is established by two springs 58, situated in respective bores 64. The idle pulley block 56 slides on two pins 66 that are mounted to the frame 2. After block 56 is positioned such that the springs appropriately tension the belt, the idle block is locked in position, such as by set screws 68 which are tightened to clamp the block to the pins.
In this example embodiment, the extension of the pantograph linkage is controlled by the positions of the [0040] outermost gripper mechanisms 5 and 6, which in turn are controlled by the position of the timing belt 11. The outermost gripper mechanism 5 is attached to the front-facing side of the loop (visible in the figure) of the timing belt 4, such as by a clamp 65 or other suitable means at a second location point. The outermost gripper mechanism 6, at the opposite end of the pantograph 44, may be similarly attached to the rear-facing opposite side of the loop (not visible in FIG. 6) of the timing belt 4 at a third point or location.
When the timing belt is rotated such that the front-facing surface of the belt moves to the right in FIG. 6, as shown by the arrow A, [0041] gripper mechanism 5 is moved toward the right in the figure, while gripper mechanism 6 is moved an equal distance to the left, thus contracting the pantograph 44 and uniformly reducing the pitch of the vacuum tips 12. Motion of the timing belt in the opposite direction expands the pantograph 44 and increases the pitch of the vacuum tips 12. Thus, the relative horizontal positioning and the expansion and contraction of the pantograph linkage is controlled in this specific example at three points: at the first point or location by the roller 7 which rolls against the roller plates 37, and at the outermost gripper mechanisms 5 and 6, rather than at only two points. That is, moving the timing belt adjusts the spacing between the second and third points along the longitudinal axis of the rails, resulting in an adjustment in the length of the linkage and of the spacing between the gripper mechanisms. Although not required, the use of three-point control reduces positioning errors due to stack-up of mechanical tolerances.
The position and motion of the [0042] timing belt 4 is controlled by a motor such as a servo motor 46 positioned within a motor housing 3. The servo motor 46 drives a drive shaft 50 through a gearbox 48. The drive pulley 52 that controls the motion of the timing belt 4 is mounted on the driveshaft 50. The servo motor 46 also drives an encoder 54 for detecting and controlling the position and motion of the servo motor 46 and the driveshaft 50 and drive pulley 52.
A [0043] controller 60 may be employed to electronically control the position of the servo motor 46. The controller may be in the form of a dedicated chip or a portion of a chip or the like, or of a programmable computer or the like, or virtually anything in between. The controller, of whatever type, may include or be connected to a user interface 62. The controller may have a look-up table with values stored therein that correspond to amounts of rotation or the positions of the shaft 50 that correspond to desired pitch settings. The user may enter a desired tray type or a desired pitch measurement or the like to trigger a look-up operation in the look-up table in the controller 60. The resulting value may then be used by the controller to determine and control the motion of the servomotor 46 so as to set the desired pitch. Alternatively, the controller may calculate the required motion or position of the servomotor 46 directly. The desired pitch information may be delivered to the controller from any source. Limit switches 24 and 25 (FIG. 1) may be used to detect the maximum and minimum extension of the pantograph by detecting the presence of the gripper mechanism 5. One of the limit switches 24, 25, may also serve as a home switch, to find a defined position after power-up, in the event that the motor's encoder/controller requires it.
Use of a non-slip tensile force-transmitting member such as the [0044] timing belt 4 allows efficient, direct conversion of rotary to linear motion and vice-versa, so that fine control of vacuum-tip pitch may be provided via the rotary servo motor 46 and the rotary encoder 54. This allows easy electronic and programmable control of the pitch, based on control of the servo motor 46. Furthermore, the pitch is always and immediately adjustable to virtually any pitch within the total range of adjustment, since the adjustment mechanism does not require nor rely on mechanical stops to define the pitches between which adjustment is desired. Of course other tensile-force transmitting members may be used, such as chain or similar drive mechanisms. Although less desirable, other drive mechanisms, including those with stops, may be used.
The present invention, as illustrated in the various examples above, provides improved positioning precision and improved flexibility in setting the pitch of a variable pitch pick and place device. The present invention is useful in any context where relatively large numbers of ICs need to be handled and/or sorted quickly and efficiently, particularly where a transfer between holders or containers of different pitch is required. The pick and place device of the present invention may thus be used to move or selectively move ICs to and from all kinds of holders or containers, including trays, bum-in-boards, and machine components such as precisors and multi-track IC runways. Devices typically utilizing such transfers include many or even most back-end processes, including, for example, Bum-in Board Loaders and Unloaders, Trim-Form Machines, and Test Handlers. [0045]
An example application is illustrated in a schematic plan view in FIG. 7. A variable pitch pick and place head (VPH) [0046] 41 is supported on an x-z actuator 80 for controlled motion in the x- and z-directions. Two VPHs (41, 41 a) may each be used at once in parallel for higher throughput, with each VPH picking devices from respective sets of two or more trays, such as trays 82, 84 and 82 a, 84 a. After a desired load of devices is picked by either VPH, the respective VPH, with the aid of the respective x-z actuator, moves the devices all at once to a respective precisor 86, 86 a. Each precisor comprises a plate 88, 88 a with precisely positioned cavities for holding the devices. The cavities typically have sloped sides so that gravity aligns the devices as they drop into the cavities in the precisor plate. The respective load head 90, 90 a then moves the devices all at once from the precisor to a burn-in board 92 for processing. The variable pitch of the VPH allows it to pick up all devices in a given tray row at once, and to set down all the devices it can carry into the respective precisor all at once, regardless of any pitch mismatch, thus markedly improving loading speed over non-variable pitch designs.
Variations within the scope and spirit of the invention discussed above will be apparent to those of skill in the art. For example: Not all of the gripper mechanisms need be movable with respect to the frame. One such gripper mechanism could, for example, be fixed relative to the frame, if desired, with the others being supportable by a pantograph or other structure so as to be movable along a first axis to establish a desired pitch between all of the grippers (including the fixed position gripper). Thus, at least a plurality of the grippers in this case are supported for this movement. Further, the number of vacuum tips or other device grippers need not be twelve in number, but can easily be more or less than this. Moreover, the device need not include only a single row of device grippers—multiple rows could be pitch-adjusted in parallel. Such variations are many and are not limited to these examples. Accordingly, the invention is defined not by the particular embodiments and variations explicitly described herein, but by the claims below. [0047]

Claims

I claim:

1. A method for moving electronic devices from a first location to a second location using a plurality of electronic-device grippers which are spaced apart from each other along a row, the method comprising:

picking up electronic devices with the electronic-device grippers at the first location and with the electronic-device grippers at a first pitch or spacing;

selecting a desired pitch or spacing for the electronic-device grippers; and

electronically controlling the adjustment of the pitch between the electronic-device grippers from the first pitch to the desired pitch.

2. The method of claim 1 further comprising moving the electronic-device grippers, and thereby the electronic devices carried by the electronic-device grippers, from the first location to the second location, and releasing the electronic devices from the electronic-device grippers at the second location.

3. The method of claim 1 further comprising picking up respective electronic devices with the electronic-device grippers from a first holder at the first location, adjusting the pitch between the electronic-device grippers to the desired pitch, and placing the electronic devices in a second holder at the second location.

4. A method for moving electronic devices from a first location to a second location with a plurality of electronic-device grippers arranged in a row and spaced apart from each other along the row, the method comprising:

picking up respective electronic devices with the electronic-device grippers at the first location and with the electronic-device grippers at a first pitch or spacing;

selecting a value corresponding to a desired pitch or spacing for the electronic-device grippers from a look up table; and

adjusting the pitch between the electronic-device grippers to a desired pitch based upon the value obtained from the look up table.

5. A method for moving electronic devices, comprising:

providing a plurality of electronic-device grippers arranged in a row and a frame supporting said plurality of electronic-device grippers for movement along the row;

picking up respective electronic devices with said plurality of electronic-device grippers; and

adjusting the spacing between adjacent electronic-device grippers to adjust the spacing between adjacent electronic devices while maintaining the center of the row of electronic-device grippers at a fixed position relative to the frame and maintaining equal spacing between adjacent electronic-device grippers.

6. The method of claim 5 wherein the act of picking up respective electronic devices with said plurality of electronic-device grippers comprises moving at least selected electronic-device gripper downwardly to a down position for picking up a respective electronic device, detecting whether all of the selected electronic-device grippers are in the down position, and activating each of the selected electronic-device gripper to grip a respective electronic device while in the down position.

7. The method of claim 6 comprising optically detecting whether all of the selected electronic-device grippers are in the down position.

8. The method of claim 6 wherein all of the electronic-device grippers are moved together to the down position.

9. A method for moving electronic devices with a plurality of gripper mechanisms, the method comprising:

moving at least one of the gripper mechanisms downward toward a down position for gripping a respective electronic device;

detecting whether the at least one of the gripper mechanisms is in the down position;

activating the at least one gripper mechanism to grip a respective electronic device;

moving the at least one gripper mechanism upward toward an up position; and

adjusting the spacing between gripper mechanisms.

10. The method of claim 9 further comprising optically detecting whether all of the gripper mechanisms are in the down position.

11. The method of claim 9 further comprising detecting whether all of the gripper mechanisms are in the up position prior to adjusting the spacing between the gripper mechanisms.

12. The method of claim 9 comprising the act of electronically controlling the adjusting of the spacing.

13. The method of claim 12 further comprising detecting whether all of the gripper mechanisms are in the up position prior to adjusting the spacing between the gripper mechanisms.

14. A method for moving electronic devices comprising:

providing a plurality of gripper mechanisms arranged in a row and carried by a pantograph linkage for movement along the row;

picking up the electronic devices with a respective gripper mechanism; and

applying a moving force to the pantograph linkage adjacent to one end of the row in a first direction and applying a moving force to the pantograph linkage mechanism adjacent to the other end of the row in a second direction opposite the first direction for varying the length of the pantograph linkage and thereby changing the spacing between the gripper mechanisms along the row.

15. The method of claim 14 wherein the moving force is applied in the first direction to the outermost gripper mechanism at the one end of the row to thereby apply the force in the first direction to the pantograph linkage through such gripper mechanism and wherein the moving force is applied in the second direction to the outermost gripper mechanism at the other end of the row to thereby apply the force in the second direction to the pantograph linkage through such gripper mechanism.

16. The method of claim 15 further comprising rotating a tensile-force transmitting member coupled to each of the outermost gripping mechanisms to apply the moving force in the first and second directions to the outermost gripper mechanisms to vary the length of the pantograph linkage.

17. A method for varying the spacing between electronic devices carried by a plurality of gripper mechanisms arranged in a row, the method comprising:

applying a vacuum to the gripper mechanisms to cause the gripper mechanisms to carry respective electronic devices;

electronically controlling the adjustment of the spacing between gripper mechanisms, to vary the spacing between the electronic devices carried by the gripper mechanisms from a first spacing to a second spacing.

18. The method of claim 17 further comprising moving the gripper mechanisms, and thereby the electronic devices carried by the gripper mechanisms, from a first location to a second location, and releasing the vacuum on the gripper mechanisms to place the electronic devices at the second location.

19. The method of claim 17 wherein the gripper mechanisms are supported on a pantograph linkage and the method further comprises the act of maintaining a first location of the pantograph linkage at a fixed position when the spacing between gripper mechanisms is adjusted to the second spacing.

20. The method of claim 19 wherein the first location is in the middle third of the row.

21. The method of claim 20 wherein the first location is at the center of the row.

22. The method of claim 17 wherein the gripper mechanisms are supported on a pantograph linkage and a tensile-force member is coupled to the outermost gripper mechanism at each end of the row, and the act of electronically adjusting the pitch between gripper mechanisms comprises electronically controlling the movement of the tensile-force member from a first position to a second position to cause a change in the length of the pantograph linkage and a corresponding change in spacing between the gripper mechanisms to the desired spacing.

23. A method of supporting electronic-device grippers so as to be of variable pitch or spacing, the method comprising:

supporting a plurality of electronic-device grippers on a pantograph having first and second ends at spaced apart locations;

extending the pantograph in a first direction to increase the pitch between the electronic-device grippers and retracting the pantograph in a second direction opposite of the first direction to decrease the pitch between the electronic-device grippers; and

restricting a first location of the pantograph from movement in the first and second directions, the first location being intermediate the first and second ends of the pantograph.

24. The method according to claim 23 wherein the first location is within the middle third of the pantograph.

25. The method according to claim 24 wherein the first location is at the center of the pantograph.

26. The method according to claim 23 wherein the act of supporting comprises supporting a plurality of electronic-device grippers on a vertically oriented pantograph.

27. The method according to claim 23 comprising the act of applying a force to respective second and third locations of the pantograph to extend and retract the pantograph, the second and third locations being on opposite sides of the first location from one another and adjacent to the respective first and second ends of the pantograph.

28. A method of extending and retracting a pantograph supporting a plurality of electronic-device grippers to vary the pitch or spacing between the electronic-device grippers, the method comprising:

coupling a tensile force transmitting member to the pantograph at first and second spaced apart locations;

driving the tensile force transmitting member in a first direction to extend the pantograph and increase the spacing between the electronic-device grippers;

driving the tensile force transmitting member in a second direction opposite to the first direction to retract the pantograph and decrease the spacing between the electronic-device grippers; and

electronically and selectively controlling the driving of the tensile force transmitting member.

29. The method according to claim 28 comprising the act of electronically controlling a drive motor to control the driving of the tensile force transmitting member.

30. The method according to claim 28 comprising the act of electronically controlling the driving of the tensile force transmitting member in response to values from a lookup table.

31. The method according to claim 28 wherein the act of driving a tensile force transmitting member comprises driving a timing belt.