Pick and place method and apparatus

A turret assembly is movable in X and Y and a turret of the assembly is rotatable to position a selected one of a plurality of spindles at a transfer station of the turret. The selected spindle is telescopic to pick a component from a supply point and to place the component at a placement point on a circuit board or the like. An assembly for squaring, centering, orienting, and/or testing a component being held by another spindle of the turret is actuated generally concurrently with extending of the selected spindle. Alternatively, the spindle at the transfer station may be retained in the retracted position during actuation of the squaring assembly. Much time is saved by loading components on the plurality of the spindles of the turret at one or more supply stations and then placing all of these components without the need for transferring back and forth between the supply and P.C. board.

PRIOR ART CROSS REFERENCES 
U.S. Pat. No. 4,458,412--Dean, et al., "LEADLESS CHIP PLACEMENT MACHINE FOR 
PRINTED CIRCUIT BOARDS":, issued July 10, 1984. 
U.S. Pat. No. 4,611,397--Janisiewicz, et al., "PICK AND PLACE METHOD AND 
APATUS FOR HANDLING ELECTRICAL COMPONENTS", issued Sept. 16, 1986. 
U.S. Pat. No. 4,721,907--Dean, et al., "APATUS FOR AUTOMATED TESTING OF 
SURFACE MOUNTED COMPONENTS", issued Jan. 26, 1988. 
BACKGROUND OF THE INVENTION 
The present invention relates to apparatus for the precision placement of 
electronic components on a hybrid circuit substrate and, more 
particularly, to the placement of small articles such as semiconductor 
chips, capacitor chips and integrated circuit chips on a ceramic substrate 
which has been preprinted with a thick film conductor pattern. 
As the name suggests, hybrid circuits are a combination of discrete and 
integrated circuit techniques. As in integrated circuits, conductors, 
resistors and conductive lands are printed on a ceramic substrate. In 
thick film technology, the printed elements are generally several mils 
thick. Then discrete chips are precisely positioned over the conductive 
lands and subsequently bonded in position in a manner to complete the 
electrical circuit. The printed conductor lands provide a pattern which 
precisely matches to the corresponding conductive portions of the chips 
that connect to the circuit elements within the chip as by solder. The 
bonded chips and substrate, with an exposed lead frame, are frequently 
encapsulated in toto in a potting compound for protection against physical 
and environmental damage. Use of unencapsulated chips on the circuit board 
allows for the manufacture of physically smaller circuits than those where 
discrete components which have already been encapsulated have their leads 
inserted into circuit boards fitted with receiving connectors or into 
predrilled holes wherein the leads are subsequently cut and clinched. A 
primary advantage of chips is their small size, some being nearly 
microscopic. Chips in the order of 0.030 by 0.030 inches square and 0.010 
thick and solder connection portions and conductor lands in the order of 
0.005 inches in height and width, and spaced apart by similar distances, 
are not uncommon. Nevertheless, for the hybrid circuit technique to be 
successful, the small chips must be positioned and oriented such that when 
placed on the substrate, all solder connection portions and lands are 
properly connected without error. This requires a high degree of precision 
in positioning which was achieved in early development of these techniques 
by human operators using microscopes and tweezers. 
The need for automatic, rapid, precise, repeatable and low cost means to 
position and bond chips on substrates was apparent if the burgeoning 
requirements of mass production in the electronics industry were to be 
met. Generally speaking, in the apparatuses which have been developed in 
the past, the chip or other small component, e.g., beam leaded components, 
are picked up by a hollow probe device which is connected to a vacuum 
source. When the probe touches the upper flat surface of the chip, the 
vacuum within the probe holds the chip against the probe end. The chip is 
then raised, translated in X and Y to the appropriate location above 
substrate, and lowered in Z onto the substrate. Prior attempts have been 
made to improve the precision of placement of the components onto the 
circuit board by combining centering fingers with the vacuum probe. Thus, 
while the probe supports the component by vacuum, the fingers center the 
component relative thereto prior to placement. Permanent bonding of chip 
to substrate is accomplished in some systems while the probe continues to 
hold the chip. In other systems, the conductive lands are pretreated with 
some form of tacky adhesive or soldering flux. The probe gently presses 
the chip surface into the tacky adhesive so that electrical contact is 
made with the conductive lands. Then the vacuum within the probe is 
released and the chip remains adhered to the substrate as the probe is 
withdrawn. A positive gas pressure within the probe is sometimes used to 
separate the chip from the probe. 
In one form of the prior art, the substrate and the chip are both 
separately, fixedly and precisely oriented and located. A transfer 
mechanism, usually utilizing a vacuum probe as described above, travels an 
invariable, repetitive path to pick up the chip and place it at one 
selected position on the substrate. Then, a new substrate and new chip are 
fed into their respective positions and the operation repeats. In another 
form, the chips start out with a degree of disorientation, for example, at 
random in a vibratory feeder bowl. The feeder bowl, in the known manner, 
operates to bring each chip in turn to a precise position. From that 
point, the design is similar to the first category; although additional 
steps to angularly orient the chip may be required intermediate the feeder 
bowl and the precisely located substrate. Still other prior art has 
combined these two categories. 
In the device of U.S. Pat. No. 4,611,397, components are successively 
placed by a hollow pick and placement spindle having motion in the X-Y and 
Z planes. The spindle, using a vacuum, picks up components individually 
from a plurality of precisely fixed input stations, e.g., component trays, 
racks, feeder bowls, behind the machine and delivers them to varied 
locations on the substrate until the component placements have been 
completed. To assure precision placement of components, the substrate 
edges and the spindle housing provide X-Y reference points, and pivoted 
fingers attached to the spindle housing center the chip on the spindle 
while correcting for slight misorientations about the Z-axis i.e., less 
than 45.degree., prior to placement, so the chip need not be precisely 
positioned at the input station for selection. Additionally, the support 
for the centering fingers is rotated about the vacuum probe axis, while 
the fingers are closed on the component, to provide control of the chip 
during angular orientation as the circuit board layout requires. 
In. U.S. Pat. No. 4,458,412, a carousel provides random vertical supply of 
taped components to a feeder assembly which feeds individual chips onto a 
nozzle of a turret-type vacuum head at a pick-up station. The turret-type 
head has four nozzles spaced 90.degree. apart about the central axis of 
the head. As the turret is rotated, a chip is transported by a nozzle 
sequentially from the pick-up station to a centering and testing station, 
a centering and orienting station, and a placement station. Located 
between the testing and orienting stations is a chip removal station for 
ejecting defective or inverted chips. Sensors are located at the adhesive 
and placement stations to detect defective P.C. boards so that they may be 
bypassed. A controller, such as a digital computer, provides additional 
monitoring and controls the operation of the machine. 
None of the prior art teaches a turret with multiple spindles thereon 
whereby the turret addresses one or more supply stations to load the 
spindles and then translates to a circuit board to place the components 
selectively at various points on the circuit board. 
SUMMARY OF THE INVENTION 
A turret assembly is movable in X and Y and a turret of the assembly is 
rotatable to position a selected one of a plurality of spindles at a 
transfer station of the turret. The selected spindle is telescopic to pick 
a component from a supply point and to place the component at a placement 
point on a circuit board or the like. An assembly for squaring, centering, 
orienting, and/or testing a component being held by another spindle of the 
turret is actuated generally concurrently with extending of the selected 
spindle. Alternatively, the spindle at the transfer station may be 
retained in the retracted position during actuation of the squaring 
assembly. Much time is saved by loading components on the plurality of the 
spindles of the turret at one or more supply stations and then placing all 
of these components without the need for transferring back and forth 
between the supply and P.C. board.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to the drawings, a component handling "pick" and "place" 
head may be attached to an overhead arm (not shown) which is translatable 
in X and Y so as to address various supply stations with the head for 
retrieving or "picking" components therefrom and subsequently "placing" 
the components at selected locations on a printed circuit board or the 
like. Hub 74 is affixed to a main bracket 20 of the pick and place head so 
as to support a turret 50 for rotation upon hub 74. A timing wheel 57 is 
attached to turret 50 so that turret 50 may be driven via timing belt 56, 
and servo motor 52 according to a programmable controller, in order to 
selectively position any of eight different spindles 64 for component 
picking or placing and/or for squaring a component which is already held 
by one of the vacuum spindles 64. 
Turret 50 has eight radially projecting tubular members 58 for guidingly 
supporting the spindles 64. Referring to FIGS. 4 and 5, each guide 58 has 
a lengthwise slot 60 through which a pin 66 of a corresponding spindle 64 
projects so as to ride in annular groove 24 of a ring 22 affixed to main 
bracket 20. The engagement of pins 66 in groove 24 maintains the retracted 
condition of the spindles 64 during rotation of turret 50. 
A gap is provided in ring 22, and a portion of spindle displacer 42 extends 
into the gap and is slidable radially relative to hub 74. Displacer 42 has 
arcuate groove 44 which cooperates with annular groove 24, when displacer 
42 is in the upward or retracted position, such that pin 66 of a spindle 
64 may pass from the annular groove 22 into arcuate groove 44 during 
rotation of turret 50. Thus, when a spindle 64 has been situated at the 
lowermost position (with reference to FIGS. 1 and 2), it can be extended 
and retracted by vertical movement of displacer 42. 
Turret 50 has holes 70 corresponding to each spindle 64, with each hole 70 
accommodating a spool valve 68 therein. When a particular spindle is 
positioned for extension and retraction via displacer 42, the 
corresponding spool valve 68 is displaceable (laterally as viewed in FIG. 
2). Extension of the piston rod of either air cylinder C2 or air cylinder 
C3 will displace the spool valve so as to provide negative, positive or 
neutral air pressure at the tip of the extended spindle. 
Spindle displacer 42 has a "dashpot" type of sliding attachment to the 
lower end of the double ended piston rod 40 of cylinder C1. This 
connection between displacer 42 and rod 40 allows spindle 64 to retract 
slightly against an air spring when the tip of spindle 64 is advanced into 
engagement with a component body during "picking" of the component as well 
as when the component body engages the printed circuit board during 
"placing" of the component. Fluid is admitted to and evacuated from 
cylinder C1 via fittings 46 and 48 according to the controller program. 
In addition to picking and placing components, it is also possible to 
square, center, and orient components about the longitudinal axis of the 
vacuum spindle and to test electrical functioning of the component. To 
that effect, a squaring assembly 90 is rotatably mounted within a support 
bracket 92 which, in turn, is slidable radially toward and away from 
turret 50 on main bracket 20 and is biased toward turret 50 by a tension 
spring 94. Bracket 92 has a screw 96 for engaging main bracket 20 so as to 
provide an adjustable limit of movement of bracket 92 in one direction 
(approximately 3/16 of an inch in a prototype of the device). Bracket 92 
is raised against the tension of spring 94 (to the position of FIG. 2) by 
means of member 36 which is attached to an upper end of double ended 
piston rod 40. Moving rod 40 so as to lower member 36 allows spring 94 to 
bias bracket 92 downwardly until screw 96 engages bracket 20, resulting in 
squaring fingers 100 of tooling 98 being positioned appropriately for 
subsequent closing upon a component being held by the uppermost spindle 
64. 
Member 38 also is attached to the upper end of the double ended piston rod 
40 of cylinder C1. Actuation rod 102 normally is biased upwardly by 
compression spring 104, and the normally opened component engaging fingers 
100 are closed when rod 102 is depressed by member 38. 
Gears 106 and 112 intermesh so that tooling 98 is rotatable about its 
longitudinal axis, upon actuation of stepping motor 110 according to the 
programmed control, so as to reorient a component which has been squared 
by and is still held in the fingers 100. Any well known connection is 
provided between the hub of gear 106 and rod 102 so that squaring fingers 
100 are reorientable about the longitudinal axis of tooling 98 in both the 
raised and lowered conditions. 
According to programmed control of an X-Y positioning system, the pick and 
place head illustrated in FIGS. 1, 2, and 8 is moved to an appropriate 
component supply such as a reeled tape feeder. When so positioned, spindle 
64 is lowered by actuation of cylinder C1 to move spindle displacer 42 
from the solid line position to the bottom most phantom line position of 
FIG. 2 for extension of spindle 64. The dashpot-like connection between 
displacer 42 and rod 40 allows displacer 42 to move (for instance, to the 
phantom line middle position of FIG. 2) during picking and placing of 
components in order to accommodate components of various heights. 
Thus, spindle 64 is extended to engage a component and hold it by vacuum 
during retraction of the spindle by cylinder C1, whereupon the turret 50 
is rotated to position another spindle for the subsequent picking 
operation. In a prototype of the invention, the pick and place head is 
provided with a transmitter which is aligned with a corresponding receiver 
located at each supply station during picking of a component therefrom so 
as to control indexing of the next component into position for a 
subsequent pick up. Having picked up a component, turret 50 is rotatable 
to position another spindle for "picking" from the same supply station. 
Alternatively, the pick and place head could be moved in X and Y to 
position each spindle at a different supply according to the needs of the 
user and the program provided to the controller. 
A reverse operation generally is performed in placing the component at a 
selected location on the circuit board. Before, during, and/or after X-Y 
positioning of the head, the turret is rotatable to position any one of 
the eight spindles for placement of a component at the selected location 
on the circuit board. Further, assembly 90 provides squaring, centering, 
orienting and/or electrical function testing of the component held on the 
uppermost vacuum spindle 64 when lowermost spindle 64 is extended. 
Alternatively, it is contemplated that relative movement could be provided 
between assembly 90 and the uppermost spindle 64 to accomplish these 
functions without the necessity of extending the lowermost spindle 64. 
OPERATION 
In preparation for performing the "picking" mode of operation: (a) 
solenoids S1 and S2 are not actuated, (b) air is routed to the bottom of 
cylinder C1 via valve V1 to ensure that the picking spindle is in the 
retracted position, (c) air is always available to an input of valve V4, 
and a plunger thereof normally is spring biased upwardly to prevent a 
fluid path through V4, (d) vacuum is always available to the hub at 76, 
and (e) spool valve 68 is displaced leftward from the position of FIG. 3 
so that the tip of the spindle is at atmospheric pressure. 
For picking, the pick and place head is positioned in X and Y such that the 
picking spindle 64 (the bottom most spindle as viewed in FIGS. 1 and 2) is 
located above a component at a supply station. Then, solenoid S1 is 
actuated to change the state of valve V1 such that positive air is 
supplied to the top and evacuated from the bottom of cylinder C1, 
resulting in extension of piston rod 40 and, in turn, extension of spindle 
64 by spindle displacer 42. With such extension, member 36 depresses the 
plunger of valve V4 so that air is ported through V4 to cylinder C2 by way 
of V2, whereupon cylinder C2 causes the spool valve 68 to be displaced to 
the position of FIG. 3. Thus, spool valve 68 completes a path between hub 
74 and spindle 64 for vacuum to hold a component on the tip of the 
spindle. 
Sensor 25 is actuated by member 36 during such extension of the spindle 64 
so that solenoid S1 is deactivated and a spring changes the state of valve 
V1 to reroute positive air through valve V1, causing cylinder C1 to 
retract the vacuum spindle 64 which is holding a component. Complete 
retraction of the spindle is detected by engagement of member 38 with a 
sensor 23 (FIG. 2) whereupon a transmitter 27 and receiver 29 are used to 
detect presence or absence of the component on the tip of the retracted 
spindle. If a component is detected on the spindle tip, turret 50 is 
indexed (a selectable amount according to the controller) so as to 
position the next appropriate spindle for extension and pick up of a 
component. 
Hub 74 is provided with an annular groove 75 (FIG. 3) by which vacuum is 
maintained on all of the spindles which are not in position for extension 
by displacer 42. During rotation of turret 50, the corresponding spool 
valve 6 for each of these spindles 64 is retained (in the position of FIG. 
3) by the friction of an O-ring 69 with the internal diameter of port 70. 
As many of the spindles 64 as desired may be loaded with components by this 
"picking" procedure. It should be noted that member 36 clears the spring 
biased plunger of valve V4 when the spindle is raised so as to disconnect 
the air path between V4 and V2 and prevent actuation of cylinders C2 and 
C3. 
For "placing" the components held on vacuum spindles 64, turret 50 is 
rotated selectively to present the appropriate spindle for extension. 
Turret 50 can be rotated prior to, during, or after repositioning of the 
overall head in X and Y so as to locate the appropriate spindle over the 
appropriate placement location on a circuit board. Solenoid S2 is 
activated to change the state of valve V2 and is maintained in this 
activated state until all of the placing operations are completed. Thus, a 
fluid path is made available from valve V2 to cylinder C3 and the control 
portion of valve V3, although no air is actually supplied via this path 
until the plunger of valve V4 is engaged by member 36. 
Next, solenoid S1 is activated to change the state of valve V1 so that the 
supply and exhaust of air for cylinder C1 is reversed so as to displace 
piston rod 40 and extend the appropriate spindle 64 for placement of a 
component on the circuit board. With lowering of rod 40, member 36 
depresses the plunger of valve V4 so that air is ported therethrough to 
valve V2 which, in turn, ports air to cylinder C3 and to the control inlet 
of valve V3. Thus, cylinder C3 displaces spool valve 68 (to the left as 
viewed in FIG. 3) so as to provide a path between positive air inlet 78 of 
hub 74 and the spindle 64. The control air supply to valve V3 causes a 
pulse of air which was previously stored therein to be supplied to the 
inlet 78 of hub 74 so that an "air kiss" ensures release of the component 
from the tip of spindle 64 during placing of the component. Valve V3 
automatically resets to capture another pulse of air therein. 
Sensor 25 detects the lowered position of member 36 so as to indicate that 
the spindle 64 is fully extended and that the controller may deactivate 
solenoid S1. Thus, the state of valve V1 is changed to reroute air 
therethrough for retraction of the spindle. It may be advantageous to 
program a delay for changing of solenoid S1 when the spindle is fully 
extended so as to allow for settling time of the spindle and/or additional 
time for orienting or testing another component by assembly 90. 
With the spindle retracted, turret 50 is rotated to link the next 
appropriate spindle 64 with displacer 42, and the pick and place head is 
repositioned over the circuit board for placing the next component 
thereon. This process is continued as required for placement of the other 
components. It should be noted that the retracted position of the spindle 
is detected by sensor 23 being activated by member 38, at which time 
transmitter and receiver system 27, 29 is used to detect the presence or 
absence of a component on the spindle. 
During each displacement of double ended piston rod 40 of cylinder C1, a 
bracket 92 is lowered and fingers 100 of a squaring assembly 90 are closed 
upon any component which is held by the uppermost spindle 64. For an 
understanding of the structure and operation of assembly 90, the reader is 
referred to U.S. Pat. No. 4,721,907 illustrating tester fingers utilized 
in testing electrical functioning of a component during squaring and 
centering thereof and U.S. Pat. No. 4,611,397 illustrating centering 
fingers which may be rotated about a central longitudinal axis of the 
device so as to reorient the component. It is contemplated in the instant 
invention to incorporate the squaring, centering, and orienting feature 
into the device of U.S. Pat. No. 4,721,907 or, alternatively, to 
incorporate the electrical function testing feature into the device of 
U.S. Pat. No. 4,611,397, in order to provide the functions required of 
assembly 90. It is preferred that the component remains on the tip of the 
spindle 64 while being operated on by assembly 90, as practiced at the 
test and orient stations of U.S. Pat. No. 4,458,412, but without extending 
spindle 64 for these functions. 
Referring to FIGS. 6 and 7, a spindle located at the component transfer 
station of the turret may be selectively extended or held in the retracted 
position during lower of piston rod 40 which, in turn, actuates the 
squaring assembly 90. In FIG. 6, the displacer 42' acts in much the same 
way as the earlier described displacer 42. However, in FIG. 7, during 
lowering of piston rod 40, air is supplied via hose 43 so as to prevent 
lowering of displacer 42' along with rod 40. Thus, a spindle located at 
the component transfer station of the turret assembly will not be extended 
during actuation of squaring assembly 90. 
The following claims are intended to cover all of the generic and specific 
features of the invention herein described and all statements of the scope 
of the invention which as a matter of language, might be said to fall 
therebetween.