Method and apparatus for mounting multilead components on a circuit board

A method for mounting one or a plurality of multilead components (25-28) on a circuit board (20) is herein disclosed. The method comprises the steps of loading a releasable template (32) with the component/components to be mounted, positioning the releasable template proximate to the board, releasing the component/components from the template onto the board such that each lead of each component is proximate to a corresponding aperture in the board, and imparting a vibratory motion (via 29 and 23) to the board thereby inserting the component/components into the board. Also disclosed are various embodiments of an apparatus for achieving this mounting method using a programmable robotic arm (FIG. 2).

TECHNICAL FIELD 
The present invention relates to the mass production of circuit boards, and 
more particularly to a method and an apparatus for simultaneously mounting 
one or a plurality of multilead components on circuit boards. 
BACKGROUND OF THE INVENTION 
The production of electrical and electronic circuit boards often requires 
the mounting of several multilead electrical components on each board. 
Usually, such mounting techniques involve manual insertion of the leads of 
the multilead components, one component at a time, in corresponding holes 
of a circuit board. Clearly, such techniques result in small throughput, 
are time consuming, and labor intensive. Moreover, with electrical 
component packages becoming smaller in size, and with the number of leads 
on each package substantially increasing to achieve higher packaging 
densities, the problem of operator fatigue becomes a major one. 
Several attempts were made to avoid the foregoing hindrances of manual 
insertion of a multilead component by resorting to automation. In the area 
of automatically mounting a multilead component or an I.C. package on a 
printed wiring board (PWB), the emphasis has been on achieving a high 
degree of accuracy in the positioning of the component held by a robotic 
hand or an automatic manipulator with respect to the holes of the PWB. 
Such high accuracies and close tolerances in the design and control of the 
robotic hand result in a complex and expensive automatic apparatus for 
accurately positioning the leads or terminals of the component with 
respect to their corresponding holes. Such an automatic apparatus is 
capable of mounting or inserting only one multilead component at a time 
into the PWB. Furthermore, the foregoing strict hand positioning 
requirements do not and cannot compensate for any dimensional deviations 
existing between the outer housing of the component and its leads. 
A technique for automatically mounting a multilead component on a board is 
described in U.S. patent application Ser. No. 382,263 filed on May 26, 
1982 and assigned to the assignee herein. Such a technique comprises the 
steps of placing the multilead component on the board such that each one 
of its leads is proximate to its corresponding hole in the board, and 
vibrating the board to cause the leads to fall into the holes. This 
technique clearly overcomes the above-mentioned strict design requirements 
on the robotic hand, as well as the component dimensional deviations 
problem. Although this technique operates satisfactorily for its intended 
purpose, it is capable of mounting only one multilead component at a time 
on the board. 
SUMMARY OF THE INVENTION 
The foregoing problems are solved in accordance with one illustrative 
embodiment of the present invention wherein a method for simultaneously 
mounting a plurality of multilead components on a board comprises the 
steps of holding the plurality of components proximate to the board, 
simultaneously placing the plurality of components on the board such that 
each lead of each component is proximate to its corresponding aperture in 
the board, and imparting a vibratory motion to the board thereby inserting 
each lead of the components into its corresponding aperture in the board. 
In a further embodiment of the invention, the holding step comprises the 
steps of loading a releasable template, having a plurality of openings 
substantially matching the dimensions of the components, with the 
plurality of components to be mounted; and positioning the loaded 
releasable template proximate to the board in a direction substantially 
parallel thereto. In another embodiment of the invention, the holding step 
comprises the steps of positioning a releasable template, having a 
plurality of openings substantially matching the dimensions of the 
components, proximate to the board in a direction substantially parallel 
thereto, and loading the openings of the releasable template with 
corresponding components to be mounted. In either one of these two 
embodiments, the positioniong step may comprise the step of controlling a 
programmable manipulator (e.g., a robotic arm) for holding the releasable 
template at a preselected coordinate position with respect to the board. 
In accordance with another illustrative embodiment, the above-mentioned 
releasable template and programmable robotic arm are used to mount a 
multilead electrical component on a printed wiring board (PWB). The method 
for achieving such a mounting comprises the steps of holding the multilead 
electrical component in an opening of the releasable template, holding the 
releasable template by means of the programmable robotic arm, placing the 
releasable template at a preselected coordinate position with respect to 
the PWB such that each lead of the component is proximate to its 
corresponding aperture in the PWB, releasing the component out of the 
opening of the template onto the PWB, and vibrating the PWB in directions 
substantially parallel to its plane thereby causing each lead of the 
multilead electrical component to be inserted in its corresponding 
aperture in the PWB. 
One advantage of the present invention is the ability to automatically 
mount a plurality of multilead components on boards regardless of 
reasonable dimensional deviations in the position of the outer housing of 
the components relative to their leads. 
Another advantage of the present invention is the ability to simultaneously 
mount several types of multilead components having diverse geometries on 
the same board without requiring operator assistance. 
A further advantage of the present invention is the capability of mounting 
a plurality of multilead components using a single programmable robotic 
arm. 
A still further advantage of the present invention is the ability to 
maximize circuit board throughput by minimizing the robotic arm motions. 
These and other advantages of this invention will appear more fully upon 
consideration of the illustrative embodiments now to be described in 
detail in connection with the accompanying drawings.

DETAILED DESCRIPTION 
Illustratively shown in FIG. 1 is a component 10 having a plurality of 
leads 11 arranged or aligned in accordance with a pattern 12 on one side 
or surface 13 of such component. The component 10, as shown, has an outer 
body housing 14 generally shaped as a parallelepiped. However, the 
hereafter described inventive concepts are also applicable to components 
having cylindrical, cubical or any other outer body shape. Also, the leads 
11 may be arranged in any type of pattern 12, such as circular, 
rectangular, square, or other geometric configurations. Moreover, the 
present inventive concepts and teachings are applicable to the mounting of 
multilead components on boards, such multilead components containing 
electrical devices, electronic circuits, other type of objects or 
articles, or any combination thereof. 
Shown in FIG. 2 is an apparatus for mounting components in accordance with 
one embodiment of the present invention. A board 20 having a plurality of 
holes or apertures 21 arranged in various patterns, e.g., 24, is mounted 
on a base 22 by means of a plurality of mounting bodies 23. A plurality of 
multilead components of various shapes 25, 26, 27, 28 are to be mounted on 
board 20. The leads of each one of the multilead components are to be 
inserted in predetermined apertures, such as pattern 24, of the board. The 
apertures 21 on the board 20 are arranged in patterns corresponding to 
those of the leads of the components 25 to 28 to be mounted thereon. As 
schematically shown in FIG. 2, the board 20 is further coupled to the base 
22 by means of a mechanism 29 capable of imparting a vibratory motion of 
controlled frequency and amplitude to the board. One way of accomplishing 
the vibratory motion of the board 20 is to use somewhat compliant mounting 
bodies 23 attached to the board. One such compliant coupling may be 
achieved by means of spring mounted legs having one end thereof secured to 
the base 22 and the other end coupled to the board 20. Alternatively, 
mounting bodies 23 may include suspension springs (not shown) having one 
end coupled to the board 20 and the other end secured to a fixed portion 
of the base 22. 
Such vibratory motion, which is preferably in the plane of the board 20, 
may be accomplished, for example, by means of a motor 30 having an 
eccentrically mounted shaft 31 thereon, which is attached to the board. 
However, other types of vibrating mechanisms, as well as vibratory motions 
in a direction substantially perpendicular to the plane of the board, are 
also within the spirit and scope of the present invention. 
In order to simultaneously mount the components 25 to 28 on the board 20, 
they are all initially held proximate to the surface of board 20. Next, 
these components 25 to 28 are simultaneously placed on the surface of the 
board 20 such that each component has its leads proximate to a 
corresponding aperture 21 in the board. The holding of the components 25 
to 28 prior to placing them on the board 20 is achieved by means of a 
releasable template 32 having a plurality of openings 34 to 37 adapted to 
receive the outer bodies of components 25 to 28, respectively. The 
dimensions of each opening 34 to 37 of the template 32 are selected to 
substantially match the outer dimensions of the components to be mounted. 
Also, each opening 34 to 37 of the template 32 is located therein to 
substantially match the position and orientation of its corresponding 
component aperture pattern 24 on the board 20. Furthermore, each opening 
34 to 37 of the template 32, such as opening 35, may comprise a pair of 
retaining protrusions or lips, e.g., 33, adapted to hold a corresponding 
component therein. As shown, the releasable template 32 comprises a 
central portion 38 releasably coupled to two outer portions 39 and 40 
along its two edges 41 and 42. The perspective view of the apparatus of 
FIG. 2 shows only one of the retaining protrusions of openings 34, 35 and 
37, the other protrusion of each opening being opposite to the one shown. 
In other words, template opening 35, for example, has one retaining 
protrusion or lip 33 located in the template outer portion 40 and the 
other retaining protrusion or lip located in the template central portion 
38. Further structural and operational details of the "opening" and 
"closing" of a releasable template in accordance with an embodiment of the 
invention will be described in connection with FIGS. 6 and 7. 
In operation of the illustrative embodiment of FIG. 2, the releasable 
template 32 is closed and the multilead components 25 to 28 are loaded in 
their corresponding openings 34 to 37 of the template. As shown in FIG. 2, 
edge 41 of the central portion 38 "cuts across" openings 36 and 37, while 
the other edge 42 of the central portion 38 "cuts across" openings 34 and 
35. The template 32 with the components loaded therein is positioned 
proximate to the board 20 in a direction substantially parallel thereto by 
means of a programmable manipulator 43, e.g. a robotic arm, operating 
under a computer control terminal 44. The programmable manipulator 43 is 
of a type capable of lifting a predetermined load comprising the 
releasable template 32 and the various components loaded therein, and of 
locating the template with sufficient accuracy proximate to the board such 
that each component is positioned near its corresponding location on the 
board. A commercially available programmable manipulator of the foregoing 
type is, for example, the PUMA Model 560 robotic arm manufactured by 
Unimation Inc. of Danbury, Conn. 
Once the loaded template 32, which is held by manipulator 43 at its wrist 
45, is positioned proximate to the board 20, the template portions 38, 39 
and 40 are separated from each other. This is achieved by laterally 
displacing portions 39 and 40 away from the central portion 38, as 
schematically shown by the directional arrows on the template portions 39 
and 40. This results in the enlargement of openings 34 to 37, and in a 
simultaneous release of the components 25 to 28 out of their respective 
openings 34 to 37 onto the surface of the board 20. The releasable 
template 32 is maintained in its parallel position proximate to the board 
20 for a delay period. During a portion of such delay period, each 
component which is placed on the surface of the board 20 is confined 
within its corresponding opening in the template 32. In other words, the 
template openings prevent each component from moving away from its 
corresponding aperture pattern on the vibrating board. At the end of the 
delay period, the template is withdrawn above the highest component 
inserted on the board, and is thus ready for a new loading cycle on a new 
empty board. 
The foregoing operational steps of the embodiment of FIG. 2 are illustrated 
in a flow chart configuration shown in FIG. 3. This flow chart diagram is 
given herein as one example for controlling and programming the 
programmable manipulator 43 to achieve the components mounting process in 
accordance with an embodiment of the invention. It is considered that 
those skilled in the art would be capable of programming the manipulator 
to interact with the various hardware elements of this illustrative 
embodiment. 
At the outset, the system is started with the START instruction of block 
50. Next, an empty board 20 is mounted on the base 22 as shown by the 
ACQUIRE EMPTY BOARD 20 instruction in block 51. The vibration mechanism 29 
is turned on thus imparting a vibratory motion to board 20 as per block 
52. Next, the template 32 which is held by the manipulator 43 at its wrist 
45, is "closed" by means of a control instruction given to the manipulator 
from its control terminal 44. Such control instruction of block 53 is of 
the type of a close hand, close grippers, or close fingers instruction 
available on most commercially available robotic arms. Subsequent to 
instruction block 53, the empty template 32 is closed, i.e., central 
portion 38 is brought in intimate contact with the two coplanar outer 
portions 39 and 40, and the template openings 34 to 37 are now reduced or 
smaller than in their "open" position. 
The loading of the template 32 with the respective components 25 to 28 to 
be mounted may be achieved manually or automatically by means of an 
appropriate component feeding mechanism. Subsequent to the loading step of 
block 54, the template 32 is positioned proximate and parallel to the 
board 20 by directing the wrist 45 of the manipulator 43 to a 
predetermined coordinate space position relative to the base 22. This is 
achieved in block 55 by feeding the programmable manipulator 43, via the 
control terminal 44, with a desired location in space for its wrist 45. 
Next, the template 32 is opened by means of a control instruction such as 
open hand, open grippers or open fingers instruction thereby releasing the 
components 25 to 28 to be mounted out of their now enlarged openings 34 to 
37 onto the surface of the vibrating board 20. Subsequent to the opening 
of the template 32 as per block 56, the template is maintained in its 
parallel position proximate to the board 20 for a period of time until the 
components are inserted, as shown by block 57. During the latter, the 
components to be mounted on the board 20 are confined within their 
respective template openings until their leads are inserted in their 
corresponding apertures 21 on the board. The foregoing period of time may 
be fixed, or may be responsive to sensing means indicative of the 
insertion state of the respective components. 
Shown in block 58 is the next step in the process which consists of 
withdrawing the open template 32 above the highest inserted component on 
the board 20 in order not to disengage any of the mounted components. The 
remaining blocks 59, 60 and 61 of the process are self explanatory in that 
the loaded board 20 is now to be removed and any new empty board is to be 
mounted on the base 22 prior to repeating the foregoing series of steps. 
Another embodiment of the invention is schematically shown in FIG. 4 
wherein the programmable robotic arm 43 of FIG. 2 is used to 
simultaneously mount a plurality of multilead components on a board 70. 
The latter is transported to a work station 71 by means of a conveyor 72. 
Work station 71 is illustratively of a vibratory type. Such a vibratory 
station 71 is capable of oscillating in a first direction 73, a second 
direction 74, or in any other direction resulting from any combination of 
the first and second directions 73 and 74. The board 70 is temporarily 
secured to the vibratory work station 71, and a vibratory motion is thus 
imparted to the board in accordance with an embodiment of the invention. A 
releasable template 75 comprising two coplanar portions 76 and 77 has a 
plurality of openings 78, 79, 80 and 81 adapted to receive a corresponding 
plurality of components (not shown) to be mounted on board 70. As shown, 
the template 75 is held at the wrist 45 of the programmable robotic arm 
43. In order not to obstruct the drawings, further structural details of 
the releasable template 75, such as its opening and closing mechanisms, 
are not shown in FIG. 4 but will be described in connection with FIG. 6. 
Illustratively shown in FIG. 4 is a components feeding arrangement 82 
comprising a plurality of differently shaped feeding tubes 83, 84 and 85. 
Each of the feeding tubes 83 to 85, which acts as a source of multilead 
components to be mounted, must be of a type capable of delivering one 
component at a time at a preselected speed or rate depending upon the 
overall speed requirements of the components mounting process. 
In accordance with an embodiment of the invention, the releasable template 
75 is loaded with the component or components to be mounted by locating 
one of its openings, e.g., 78, adjacent to the feeding tube 83, and by 
transferring a component out of tube 83 into opening 78 of template 75. 
During such an operation, template portions 76 and 77 are held together 
such that the component transferred into opening 78 is held within such 
opening by means of a pair of retaining protrusions or lips (not shown) 
similar to the one described above in connection with FIG. 2. In order to 
transfer a component out of the template 75, template portions 76 and 77 
are "separated" from each other thereby enlarging opening 78 and releasing 
the component out of its corresponding opening. 
The loading of the releasable template 75 with the plurality of components 
to be mounted on board 70 is illustratively accomplished by first locating 
each opening 78 to 81 underneath its corresponding feeding tube 83, 84 or 
85. Next, the components to be mounted are transferred from their 
respective feeding tubes to their corresponding matching openings of the 
template 75. Preferably, the loading of the releasable template 75 is 
achieved by sequentially locating each one of its openings underneath the 
appropriate feeding tube and by sequentially transferring the components 
out of the feeding tubes. The placing of the components on the board 70 is 
achieved by positioning the components-loaded-template 75 in substantially 
parallel spaced relation to the board 70 at predetermined coordinate 
positions with respect thereto, and by simultaneously releasing the 
components out of their respective openings 78 to 81 of the template onto 
the board. The positioning of the template 75 by means of the programmable 
robotic arm 43 may be substantially aided by using a set of auxiliary 
locating devices, e.g., tapered pins 86 and 87, attached to a 
non-vibrating portion 88 of the work station 71 and adapted to be inserted 
in mating apertures 89 and 90 of one portion (e.g., 77) of the releasable 
template 75. 
The various operational steps of the embodiment of FIG. 4 are illustrated 
in a flow chart configuration shown in FIG. 5. This flow chart diagram is 
given herein as one example for controlling and programming the 
programmable manipulator 43 to achieve the components mounting process in 
accordance with this embodiment of the invention. It is considered that 
those skilled in the art would be capable of programming the manipulator 
to interact with the various hardware elements of this illustrative 
embodiment. The flow chart of FIG. 5 is similar to the one described in 
FIG. 3, and comparable functional and programming steps in the former have 
the same reference numerals as their counterpart in the latter. In 
accordance with the embodiment of FIG. 4, the loading of the template 75 
is achieved by locating an unfilled template opening beneath the feeder 
(block 91), transferring a component from the feeder onto the template 
opening (block 92), and repeating the foregoing two steps (block 93) until 
the template is fully loaded. The remaining operational steps of this flow 
chart, i.e., steps 50 to 53 and 55 to 61, are similar to the corresponding 
steps described above in connection with FIG. 3. 
FIG. 6 illustratively shows a releasable template 100 in its "open" or 
released position in accordance with a further illustrative embodiment of 
the invention. The releasable template 100 may be used in the above 
embodiments of FIGS. 2 and 4 as a substitute for templates 32 and 75, 
respectively. For purpose of illustration only, releasable template 100 is 
shown as having two coplanar portions 101 and 102. However, releasable 
templates having more than two portions, such as template 32 of FIG. 2, 
are well within the spirit and scope of the present invention. As shown in 
FIG. 6, template portion 101 has a plurality of indentations 103', 104', 
105' and 106' along an edge 107 thereof. Similarly, template portion 102 
has also a plurality of indentations 103", 104", 105" and 106" along an 
edge 108. The two coplanar template portions 101 and 102 are positioned 
with respect to each other to form a plurality of resulting openings 103, 
104, 105 and 106 respectively comprising the combination of indentations 
103' and 103", 104' and 104", 105' and 105", and 106' and 106". Opening 
105, adapted to receive a circular component, comprises a reference notch 
109. The latter enables a proper positioning of a circular component (not 
shown) within the template by aligning the notch with a corresponding 
reference key located on the housing of the component. 
The overall dimensions of these openings 103 to 106 in their "closed" 
position are selected to be somewhat larger than the dimensions of the 
outer bodies of the components to be mounted. Each opening, e.g., 103, 
comprises a pair of retaining protrusions or lips 110 and 111, adapted to 
hold a corresponding component within such opening. These retaining lips 
110 and 111 are best shown in the cross-sectional view of FIG. 7. Also, 
the respective locations of the openings 103 to 106 within template 100 
are selected to substantially correspond to the intended locations of the 
components on the board on which they are to be inserted. 
As mentioned above in connection with the embodiment of FIG. 4, in order to 
facilitate the positioning of the template 100 with respect to a board, 
portion 101 of the template 100 comprises a pair of locating apertures 112 
and 113. The positions and shapes of these apertures 112 and 113 are 
selected to match those of a pair of mating locating pins (such as 86 and 
87 in FIG. 4) attached to a non-vibrating portion of the work station. In 
a preferred embodiment of the invention, both the locating pins (not 
shown) and their mating apertures 112 and 113 are tapered, thereby 
substantially aiding the positioning step of the template. 
One arrangement for coupling template portion 101 to template portion 102 
may comprise two pairs of permanent magnets of which only one pair of 
magnets 114 and 115, respectively embedded in opposite cavities 116 and 
117 within template portions 101 and 102, is shown. The magnets 114 and 
115 are poled to repel each other thereby causing a repulsion force 
between template portions 101 and 102. In other words, the repulsion force 
generated by the two magnets 114 and 115 causes the edges 107 and 108 to 
normally separate from each other resulting in the somewhat enlarged 
openings 103 to 106 when the template is in its "open" position. Other 
means for generating a repulsion force between portions 101 and 102 may be 
used, e.g., a spring arrangement or dual acting air cylinders inserted in 
cavities 116 and 117 of template portions 101 and 102 may be used to repel 
portions 101 and 102 from each other. 
The coupling arrangement further comprises a pair of fastening bolts 118 
and 119 attached to a coupling bar 120 by means of a pair of nuts 121 and 
122, respectively. Fastening bolts 118 and 119 are slidably engaged with 
at least one of the two template portions 101 and 102 in order to permit 
their coplanar relative movement when the template is to be opened or 
closed. Fastening bolt 119 is engaged in passages 123 and 124 of template 
portions 101 and 102, respectively. Similarly, fastening bolt 118 is also 
engaged with the two template portions. Since the coupling bar 120 is held 
against the template portion 102, the tightening or loosening of the nuts 
121 and 122 will control the maximum distance or gap between edges 107 and 
108, and in turn will control the dimensions of the openings 103 to 106 
when the releasable template is in its "open" or released position. As 
mentioned above, the repulsive permanent magnets 114 and 115 will insure 
that the foregoing distance or gap between the edges 107 and 108 is 
maintained. The releasable template 100 may be held from a portion 125 
thereof, the latter being dimensioned and adapted to be coupled to the 
wrist of the programmable robotic arm of the type described above in 
connection with FIGS. 2 and 4. However, holding the releasable template 
from any other part or portion thereof will not affect its operation 
provided that the two coplanar template portions 101 and 102 are not 
simultaneously held by the robotic arm. 
The closing of releasable template 100 is achieved by coupling an actuator 
126 to the bar 120 such that a displacement output cylinder 127 of the 
actuator is positioned against the template portion 102. Actuator 126 may 
be an electrical solenoid, an air cylinder, or any other well known device 
capable of displacing a cylinder or small shaft in response to a control 
signal. The template close/open control signal corresponds to the 
close/open hand or grippers signal usually available on programmable 
robotic arms. The close template control signal causes the actuator 126 to 
push its output cylinder 127 against template portion 102 and to close the 
template 100 by forcing the edge 108 of portion 102 against the edge 107 
of portion 101. In other words, since the template portion 101, the bolts 
118 and 119, and the coupling bar 120 are coupled together, template 
portion 102 is the only part of the template coupling arrangement capable 
of moving in response to the force exerted by cylinder 127. Opening or 
releasing of the template 100 is achieved by removing the control signal 
applied to the actuator 126 thus retracting its cylinder 127 and returning 
the template portion 102 to its initial position away from template 
portion 101 due to the repulsive force generated by permanent magnets 114 
and 115. 
Shown in FIG. 7 is an end cross-sectional view of template 100 of FIG. 6 
along line 7--7 thereof. The retaining protrusions or lips 110 and 111 are 
dimensioned such that a multilead component to be mounted is retained 
within its corresponding template opening 103 when the template 110 is in 
its "closed" position. In the "open" position of the template 100, as 
shown in FIG. 7, the lips 110 and 111 are separated from each other 
thereby enabling the multilead component to be released out of its opening 
onto a board. 
The above-described coupling principles are readily applicable to 
releasable templates comprising more than two coplanar template portions. 
For example, in the embodiment of FIG. 2, the releasable template 32 
comprises the central template portion 38 and the two outer template 
portions 39 and 40. The coupling between the central portion 38 and the 
outer portion 39 may be achieved by positioning in each one of these two 
template portions, along their common edge 41, a pair of permanent 
magnets. The magnets in the central portion 38 are poled to repel those in 
the outer portion 39. Similarly, the coupling between the central portion 
38 and the outer portion 40 may be achieved by positioning in each one of 
these portions 38 and 40, along their common edge 42, a pair of permanent 
magnets. The latter in central portion 38 are poled to repel the magnets 
in outer portion 40. Thus, due to the presence of these repelling magnets, 
a gap is formed on each side of the central portion 38 along its edges 41 
and 42. Furthermore, a pair of fastening bolts, a coupling bar and a 
selectively energizable actuator of the type described above, would enable 
the "opening" and "closing" of the three-portion releasable template 32 in 
a similar way as the one described above in connection with the 
two-portion releasable template 100. 
The foregoing illustrative embodiments have been presented merely to 
illustrate the pertinent inventive concepts of the present invention. 
Numerous modifications can be made by those skilled in the art without 
departing from the spirit and scope of the invention.