Carousel pin stacker

Automation of stacking of lamina included in a modular circuit package is provided by use of a plurality of heads carried on a preferably rotating head transport assembly. The head transport assembly is movable between two locations in which heads simultaneously brought to respective supply, alignment and disposal stations alternately pick up or deposit lamina, plates, separator sheets or protective sheets, respectively. Each lamina, sheet or plate deposited at the alignment station is pressed down over elongated alignment pins while maintaining only a short protrusion of the alignment pins above the existing stack. Continuous production is provided by carousels which bring alignment fixtures to the alignment station and magazines containing lamina to the supply station. Selection among lamina is provided by an elevator assembly which moves a magazine to a location at which a desired lamina can be selected therefrom, preferably under computerized control. The capacities of the alignment fixtures, magazines, carousels and supply stations support production of a plurality of stacks of lamina on an alignment fixture and continuous production of a plurality of production runs without resupplying the apparatus with lamina or plates.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to the manufacture of modular 
electronic circuits and, more particularly, the automated manufacture of 
multi-layer modules (MLM), especially multi-layer ceramic modules (MLC). 
2 . Description of the Prior Art 
In electronic circuits and high-speed logic circuitry, in particular, 
reduction in size and increase in integration and packaging density has 
yielded substantial performance improvements due to reduced signal 
propagation time over shorter paths and increased noise immunity due to 
reduced capacitive and inductive coupling to conductors and other effects. 
For this purpose, modular circuits have been in use for several years to 
allow connection of numerous integrated circuit chips of diverse types and 
formed by different and potentially incompatible technologies within a 
single, compact package. Modular circuits also provide advantages of 
improved heat dissipation, regulation of temperature among chips, 
stability and protection for complex connection arrangements which are 
embedded therein and the possibility of electrostatic shielding being 
incorporated into the design. 
Modular circuits are formed by a plurality of lamina, each having a 
conductive pattern formed on one or both sides and perforations, known as 
vias, filled with conductive material for making connections between 
lamina. Generally, the conductive patterns and filling of vias is 
performed by screening of conductive paste through a mask using specially 
designed machinery. Each conductive pattern will generally be unique for 
each lamina of a modular circuit. The lamina are individually placed in a 
stack and carefully aligned with previously placed lamina. Once assembled 
and aligned, the lamina are joined by known methods into a unitary body 
such as by sintering of uncured ceramic lamina, known as green sheets, or 
fusing or bonding of thermoplastic lamina. 
Such modular circuits may be extremely complex and require hundreds of 
sequentially performed processes (with testing and repair between at least 
small groups of steps) to produce. For example, the lamina may be punched 
to form an array of vias, screening is done to fill vias and form 
conductive patterns (implying that a production run for each unique 
pattern will be performed for each required pattern forming a plurality of 
identical lamina to be eventually be placed in each of a like plurality of 
modular circuits), a covering to protect the pattern and avoid 
contamination applied to each lamina, selection and ordering of the 
lamina, removal of the covering, placement and alignment of the lamina and 
joining of the lamina. 
Most of the sequentially performed process steps subsequent to the 
screening process must be performed manually due to the requirement for 
extremely high alignment accuracy and only small groups of steps have, to 
date, been automated. In spite of the substantial expense of such labor 
intensive processes, the performance of modular circuits often justifies 
the expense since no reasonable alternatives providing comparable 
performance and manufacturing flexibility and reliability are available. 
The manufacturing process is further complicated by the need for avoidance 
of contamination of the lamina while being stacked together and the number 
of unique lamina which must be stacked together in a usually critical 
order to form the desired connection paths which will be embedded in the 
final modular circuit. While so-called clean rooms are well-known and 
utilized in many critical manufacturing processes, such clean rooms are 
expensive to build and maintain. Further, the presence of personnel 
represents an unavoidable source of contamination, as do the activities 
carried out in such an environment. Similarly, the possibility of human 
error in assembly (e.g. lamina order or alignment during assembly of the 
lamina stacks) is also unavoidable. While the possibility of repair (known 
as an engineering change or, simply, EC) of modules which may fail tests 
performed during the course of manufacture exists and is also provided for 
in the design of lamina, a gross error in lamina order or alignment is 
unlikely to be repairable; adding to the cost of functional modules 
produced. 
It has also been the trend in electronic devices that once a new technology 
has been introduced and experience gained with manufacturing and design of 
circuitry using that technology, the technology is applied to other more 
economically accessible devices. The increased performance and 
functionality provided by the new technology increases demand for 
application of the technology to an increased variety and quantity of 
products. By the same token, the increased experience with design and 
manufacturing processes tends to increase manufacturing yield and reduce 
cost of exploiting the new technology in a wide variety of products. 
However, both the compromise of the manufacturing yield and labor costs 
attributable to extensive human intervention in the manufacturing process 
for modular circuit packages has prevented sufficient reduction in cost of 
modular circuits for widespread use of modular circuits at the present 
time. Further, production volume is far too limited at the present time to 
satisfy demand which would accompany use of modular circuits in a wide 
variety of products or even data processors usable as personal computers. 
Efforts to accomplish some degree of automation of the assembly process 
has not provided for any significant increase in throughput since all 
parts of the assembly process must be not only automated but integrated in 
order to provide for a continuous assembly and to achieve the needed 
increase of production. 
It has similarly been a trend in microelectronics that, as a technology 
matures, complexity increases within that technology until another 
technology is found which overcomes that complexity. While modular 
circuits at the present time generally include from five to nine lamina, 
it is foreseeable that modular circuits will soon be designed having much 
greater numbers of lamina. This projection or expectancy also presents 
difficulty for automation of significant portions of the assembly process 
since the design and fabrication of machines for automation of the 
assembly process is very costly and such a machine might quickly become 
obsolete if larger numbers of lamina in a single modular circuit package 
could not be accommodated. Likewise and/or alternatively, it is 
foreseeable that modular circuit packages could be increased in chip 
mounting area to accommodate foreseeable increased complexity, as well, 
and there is a trade-off between the cost of larger apparatus for 
automation of an assembly process which would accommodate potentially 
larger modular circuits including the overhead expense of space to house a 
larger apparatus than currently necessary and the cost of a smaller 
apparatus which may become obsolete within its service lifetime. 
As alluded to above, it is the general practice to make production runs of 
each of a plurality of lamina for each required pattern in a modular 
circuit design and to store the lamina in accordance with the connection 
pattern formed thereon until the lamina are selected in an order specified 
by the design, placed in a stack, aligned and joined together into a 
unitary, modular structure. Therefore, division of the manufacturing 
process between the screening and assembly processes has been the general 
practice. However, since alignment has heretofore required manual 
performance and is inseparable from the selection and placement 
operations, it has not appeared feasible to automate this group of 
operations. Uncured ceramic green sheets are also very delicate and 
subject to damage during placement and alignment and such delicacy has 
hindered efforts at automation of the assembly process. 
Further, the number of operations in each of the selection and placement 
operations has complicated any attempts to automate any significant 
portion of the process. For example, once selection of a lamina suitable 
to the sequence in accordance with the design of the modular circuit has 
been made, a protective covering must be removed and disposed of. Then the 
surface must be cleaned of any contaminant particles which might reach a 
surface of the lamina while it is unprotected by covering before placement 
and alignment. Additionally, after alignment has been accomplished and 
assembly is complete, storage until the lamina can be joined has proven 
difficult and to require substantial space, as well as further precautions 
against contamination of exposed surfaces. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide automation of 
the assembly of modular circuit packages including ordering, cleaning, 
placement and alignment of lamina. 
It is another object of the present invention to provide for efficient 
handling and storage of a plurality of lamina assemblies. 
It is a further object of the invention to provide an arrangement which 
will provide for continuous assembly of modular circuit packages. 
It is yet another object of the invention to provide an arrangement which 
will provide for automation of the assembly of modular circuit packages 
while reducing the cost of maintaining a clean production environment and, 
at the same time, reducing the likelihood of lamina contamination during 
assembly. 
It is a yet further object of the invention to provide an apparatus for 
automation of assembly of modular circuit packages which can accommodate a 
plurality of stacks of modular circuit package lamina appropriate to 
current modular circuit designs as well as a plurality of production runs 
and yet accommodate manufacture of modular circuit packages of increased 
numbers of lamina. 
It is yet another object of the invention to provide a relatively 
inexpensive apparatus for automation of modular circuit package assembly 
which can be inexpensively modified to accommodate lamina of greater 
dimensions than currently in use. 
It is another, further object of the invention to provide for reduced 
restriction on the working environment of personnel during assembly of 
modular circuit packages. 
It is yet another, further object of the invention to provide a compact 
arrangement for automating assembly of modular circuits which can, 
nevertheless, accommodate the inclusion of many more lamina of 
substantially greater area than is currently the practice in modular 
circuit design. 
In order to accomplish these and other objects of the invention, an 
apparatus for assembly of a stack of lamina is provided including first 
and second supply stations, an alignment station, a first further station, 
a head transport assembly carrying first, second and third heads at 
locations allowing simultaneous alignment of the heads with a respective 
one of the stations, and an arrangement for moving the head transport 
assembly and controlling the respective heads such that materials at the 
first supply station are alternately transported to the alignment station 
and the further station and material from the second supply station is 
transported to the alignment between transportation of material from the 
first supply station to the alignment station. While elongated alignment 
pins are provided on alignment fixtures for precise registration during 
automated stacking, the alignment station provides for maintaining only a 
short and constant protrusion of alignment pins above the stack while 
supporting the lamina stack along the alignment pins as each lamina is 
added.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
Referring now to the drawings, and more particularly to FIGS. 1-3, there is 
shown, in plan view in FIG. 1 and perspective view in FIGS. 2 and 3, the 
preferred layout of an arrangement 100 for automating assembly of modular 
circuit packages in accordance with the invention. In general, as most 
clearly seen in the plan view of FIG. 1, the preferred form of the 
invention is laid out in two paths 110, 111 at a 90.degree. angle to each 
other. A carousel 120, 130 is located at each of the distal ends of the 
paths and a turntable 140 is placed at the juncture of the paths. (The 
term "carousel" will be used to connote unidirectional, though 
incremental, rotational movement and the term "turntable" will be used to 
connote bidirectional rotational movement, in the preferred case through 
only 90.degree., corresponding to the angle between the paths.) It should 
be understood that the layout of assembly 100 and motion of the carousels 
120, 130 and turntable 140 are not critical to the practice of the 
invention but are, nevertheless, considered highly preferred and 
advantageous to the efficiency and simplicity of design of the invention, 
as will be discussed. In particular, the common movement of heads carried 
by head assembly 140, regardless of how such movement is achieved, allows 
high speed and efficiency of operation to be realized together with high 
positional precision of lamina transportation and assembly and removal of 
protective material. 
It should also be understood that carousel 120, shown in FIG. 3 but omitted 
from the embodiment of the invention shown in FIG. 2, is not necessary to 
the practice of the invention for modular circuits of current designs but 
is, nevertheless, considered highly advantageous for continuous production 
and high throughput, at present, and potentially necessary for automated 
production of modular circuits having designs of increased complexity 
beyond that of current designs. Further, it is to be understood that while 
the present invention is considered particularly applicable to assembly of 
green sheets into multilayer ceramic (MLC) modules, with respect to which 
the invention will be discussed, the invention is not limited thereto but 
can be used to advantage with lamina formed of other materials and used to 
produce other devices which are assembled from such lamina where high 
alignment accuracy and freedom from contamination are important. 
The path 110 beginning with carousel 120 supplies lamina to the apparatus 
and includes at least one magazine transport assembly 160 for 
transportation of a magazine (e.g. 150) containing a plurality of green 
sheets having necessary connection patterning in accordance with a 
particular modular circuit design. If carousel 120 is included, the 
magazine transport assembly 160 includes a portion 170 for horizontal 
transportation of a magazine from carousel 120 to a location at which 
green sheets are removed therefrom. In either embodiment of the invention, 
an elevator portion 180 is provided for moving a magazine 150 vertically 
in accordance with the particular green sheet type (e.g. connection 
pattern) to be selected. 
In both embodiments, a further provision is preferably made for horizontal 
transport of a stack of green sheets from magazine 150 toward rotating 
head assembly 140 to a location at which they may be more readily accessed 
by one of the heads thereon without mechanical interference of a head 
(e.g. 605 of FIG. 6) and the magazine transport assembly 160. A preferred 
arrangement includes a track 181 and some suitable form of actuator to 
move a product tray 182, containing a stack of green sheets, from the 
magazine 150 to the location shown in FIGS. 2 or 3. 
As noted above, carousel 120 is not necessary to the practice of the 
invention and can be omitted. However, inclusion of carousel 120 is 
advantageous to continuous production, high manufacturing yield and 
accommodation of more complex modular circuit designs since it can provide 
for plural magazines to be loaded into the apparatus at a single opening 
of a clean enclosure which will be described below for continuous supply 
of green sheets or, alternatively, provide for a much increased number of 
types of green sheets from which selection can be made, or both. 
The path beginning (or terminating) with carousel 130 includes a plurality 
of alignment fixtures 190 and provides for a continuous supply of assembly 
trays on which MLCs are assembled from lamina and will hereinafter 
sometimes referred to as a tray feed assembly. The alignment fixtures 
cooperate with an alignment station 195 which provides for exact and 
reproducible alignment of the assembly trays with turntable 140 for 
stacking of the lamina. The alignment station 195 also provides for 
establishing a desired and favorable stacking hole pin depth, preferably 
about 0.040 inches, and seating of each green sheet against a previously 
stacked green sheet as it is assembled. 
The actual assembly of green sheets into MLCs is performed by a plurality 
(preferably four) heads mounted on turntable 140, hereinafter sometimes 
referred to as a rotating head assembly. The respective heads mounted 
thereon, as will be discussed in more detail below, provide the respective 
functions of removing protective covering from the green sheets and 
disposing of the covering as the green sheets are selected, gripping of 
the green sheet and transporting it to an assembly location and picking up 
and transporting spacer sheets (2) and plates which allow plural MLCs of 
current design to be assembled on a single assembly tray and sintered or 
otherwise laminated concurrently subsequent to the operation of the 
invention. This important feature of the invention also allows production 
of circuit package designs having much increased numbers of lamina than 
are needed in current MLC designs but which future designs may require. 
All of these functions are provided by the preferred form of the invention 
in the course of a single bi-directional excursion of the rotating head 
assembly through an angle of 90.degree.. 
Before proceeding to a discussion of the details of the apparatus 100 of 
FIGS. 1-3, it is important to an appreciation of the invention that 
automation of the electronic module manufacturing process in accordance 
with the invention allows enclosure of the apparatus within an environment 
which may be readily, effectively and inexpensively maintained at an even 
higher level of freedom from workpiece contamination than a so-called 
clean room, in which the apparatus will generally be placed in service. 
Specifically, clean rooms require elaborate and expensive air flow and 
filtration systems to remove particles and volatile chemicals from the 
atmosphere and regulate air flow to a generally vertical direction in 
order to trap and/or remove particles and gases over the shortest possible 
path before such particles can settle on work pieces being processed by 
human workers therein or chemicals affect exposed material surfaces. 
However, both machinery and human workers represent sources of contaminant 
particles and chemicals. While generation of particles by machines can be 
controlled to a substantial extent by placing covers and shrouds around 
moving parts, particles and vapors from human workers is much less readily 
controllable, even with special clothing and the like. Even movements of 
personnel can cause horizontal air currents which may dislodge particles 
from a surface and circulate them in the atmosphere. Therefore, separation 
of the environment of the manufacturing process to the extent possible 
from exposure to human workers will result in much reduced contamination 
of the articles manufactured. 
Specifically, FIG. 4 shows a suitable enclosure 400 for the embodiment of 
the invention shown in FIG. 2 (e.g. without carousel 120). Similarly, FIG. 
5 shows an enclosure 500 suitable for enclosure of the embodiment of the 
invention shown in FIG. 3. Both enclosures are formed of a framework of 
interconnecting elements 401, 501 such as formed tinplate or extruded 
aluminum which are arranged to interlock with each other or other pieces 
made for the joining thereof, details of which are not important to the 
invention. These elements are also preferably formed to support panels 
402, 502 and access doors 404, 504 which may be of any suitable material, 
transparent, translucent or opaque, which are oriented vertically to 
prevent horizontal air currents within the enclosure. Accessories such as 
light fixtures 503 and storage cabinets (e.g. 405, 505) are also supported 
by the interlocked framework of elements 401, 501. The panels extend as 
closely as is practical toward the floor and ceiling and the air currents 
developed by the clean room environment, itself, will be much more 
effective at removing particles and gases within the enclosure and 
separated from human workers. It is preferred to compensate for floor 
irregularities and adjust panel proximity to the floor with screw supports 
506. 
For access to the machine 100 under normal operation, doors 404, 504 
provide access to elevator mechanism 180 of the embodiment of FIG. 2 or 
carousel 120 of the embodiment of FIG. 3, respectively. Additionally, 
enclosures 400, 500 include similar workstations 410, 510, contiguous with 
and sharing a common wall with a wall of the enclosure at the termination 
of path 111. Access to carousel 130 for inserting alignment plates at 
locations 190 thereon and removal of assembled stacks of green sheets is 
provided through closeable window 507. The apparatus 100 is preferably 
computer controlled and the manufacturing process monitored by computer; 
the keyboard and monitor 508 of which may be conveniently located above 
window 507. The remainder of the workstation 410, 510 is unimportant to 
the practice of the invention but the form shown is considered to be 
preferable. 
Central to the arrangement and function of apparatus 100 is turntable 140, 
shown in plan view at a rest position in FIG. 6 and sometimes referred to 
hereinafter as a rotating head assembly or head transport assembly. 
Turntable 140 includes a circular base plate 610 pivotably mounted at and 
preferably driven from a central shaft 615. Plate 610 also advantageously 
carries pneumatic valve banks and pneumatic controllers 630, 640 for 
operation of the plurality of heads mounted thereon in order to simplify 
and reduce fatigue in connections necessary to control the various heads 
of the rotating head assembly. It should also be understood that rotation 
is considered to be a highly preferable arrangement for providing common 
motion of the heads, particularly when reciprocated as is also highly 
preferred. However, neither rotary motion nor reciprocation is 
indispensable to the practice of the invention and, for example, 
monodirectional rotation or reciprocating linear motion or other common 
motion of the heads could be used. 
It is important to an understanding of the features of the invention which 
will now be explained with reference to FIGS. 6, 6A and 6B to note that 
four stationary processing stations 601-604 cooperate with three or four 
heads 605-608 mounted on the rotating head assembly or turntable 140. Each 
of these heads has a different and specific function. Specifically, green 
sheet pick-up head 605 is arranged to pick up a green sheet from a 
magazine 150 (FIG. 1) at a supply station 601 and transport it to the 
alignment station 602. Plate pick up head 606 performs a similar operation 
for separation plates between plate supply station 603 and alignment 
station 602. Spacer sheets used for protection of green sheets and 
inserted therebetween in magazine 150 or other type of product tray 182 
(FIGS. 2 and 3), preferably useable together with magazine 150 to 
facilitate extraction from the magazine 150, are removed therefrom by 
spacer pick-up head 608 at the green sheet supply station 601 and 
transported for disposal at disposal station 604. A similar operation 
could be performed between stations 603 and 604 by head 607, if desired 
and a suitable head 607 provided. 
In FIGS. 6A and 6B, turntable/rotating head assembly 140 is schematically 
illustrated in the rest and active positions, respectively as dertermined 
at 620 of FIG. 6. The motion of the turntable 140 subsequent to head 
operations at these respective positions is shown by arrows A and B, 
respectively, whereby all heads are brought to the alternate positions at 
which each head performs another action, as may be required. 
More specifically, when turntable 140 is at the rest position as shown in 
FIG. 6A, green sheet pick up head 605 picks up a green sheet at supply 
station 601 while plate pick up head 606 may deposit a separator plate at 
alignment station 602, as required, and, in any case, is available as a 
mandrel against which green sheets (and separator plates and mylar 
separator sheets, if used) may be pressed for relative slight downward 
movement of a lamina on alignment pins as will be described in more detail 
below and with reference to concurrently filed U.S. patent application 
Ser. No. 08/650,078 (Attorney's Docket No. FI9-96-021), which is assigned 
to the assignee of the present invention and hereby fully incorporated by 
reference. Further, spacer pick up head 608 is in position to dispose of a 
protective spacer sheet at station 604 and, if provided, head 607 can pick 
up a similar sheet or other object at plate supply station 603 for 
transport to disposal station 604. It should be noted that each of these 
functions is either completed at the home position or begun at that 
position to be completed when the turntable 140 is rotated 90.degree. 
(counter-clockwise, as illustrated in FIG. 6A) to an active position which 
will now be described. 
When turntable 140 is rotated to an active position as shown schematically 
in FIG. 6B, green sheet/lamina pick up head 605 is in position to deposit 
a green sheet at an alignment station 602, plate pick up head is in a 
position at plate supply station 603 to pick up a separator plate from a 
stack of similar plates (provision of a six inch stack of ninety-six 
plates each 1/16 inch thick is preferred) raised by an actuator (not 
otherwise shown) as plates are removed therefrom, if a plate is needed, 
and spacer pickup head 608 is in position at product supply station 601 to 
pick up a protective spacer sheet from magazine 150 or product supply tray 
for return to disposal station 604 when turntable 140 is again rotated 
90.degree. in the opposite (clockwise as illustrated) direction to return 
to the rest position. If head 607 is provided and had picked up an object 
at plate supply station 603, it would be in a position to deposit it at 
station 604. 
It should be noted that at the active position, heads 606 and 608 can pick 
up items at supply stations 601 and 603 while green sheet pick up head 605 
deposits a green sheet at alignment station 602 (and, possibly, head 607 
deposits an item at disposal station 604). Conversely, at the rest 
position heads 606 and 608 deposit separation plates and protective spacer 
sheets at alignment station 602 and disposal 604, respectively, while head 
605 picks up a green sheet at green sheet supply station 601 from which 
the protective spacer sheet has been previously removed. Thus, when viewed 
from the standpoint of product supply station 601, a green sheet or a 
protective spacer sheet is picked up for each movement of turntable 140 
and both are accomplished, transporting green sheets and protective spacer 
sheets in opposite directions in a single cycle of movement from the rest 
position to the active position and return. Similarly, viewed from 
alignment station 602, a green sheet is deposited and either a separator 
plate is deposited and/or the most recently deposited green sheet or mylar 
separator sheet pressed down in a similar single cycle of turntable 
movement from the rest position to the active position and return. 
As a perfecting feature of the invention, while a green sheet is in transit 
between the home and rest positions, it is possible to further clean the 
green sheet by passing it adjacent an air supply nozzle 651 and vacuum 
arrangement 650. The pair of air nozzle and vacuum arrangement prevent 
particles dislodged from the green sheet from being placed into the 
environment atmosphere. Preferably such an air nozzle and vacuum 
arrangement are provided for each side of the green sheet. 
While turntable 140 is in motion between positions (or before and/or after 
such motion, as may be needed), elevator arrangement 180 is activated to 
raise or lower magazine 150 to a position at which the next design of 
green sheet to be stacked is stored. In the embodiment of FIG. 3, a 
magazine which is in use may be lowered onto carousel 120 and carousel 120 
rotated to present another magazine which is then lifted to a position 
required to access the next green sheet design. 
A side view of the elevator assembly (viewed in the direction parallel to 
path 110) is shown in FIG. 7. Many of the details shown in FIG. 7 are not 
critical to the successful practice of the invention and alternatives will 
be apparent to those skilled in the art in view of the following 
description just as the function and interaction of many of the details 
illustrated will be readily apparent to those skilled in the art and 
detailed description thereof is unnecessary. However, the detailed 
illustration and the following description are provided as being presently 
preferred by the inventor. 
Specifically, a track 700 is provided and supported by a stationary frame 
such as 701. A moveable elevator assembly includes bearings 702 which 
slidably engage track 700, preferably with bearings such as rollers, not 
shown, to prevent wear and reduce vibration and lost motion. A 
counter-weight system 703 including separate weights 704 and connected to 
the moveable elevator assembly at 706 by cable 705 which passes over 
pulleys at the top of the stationary frame 701, as shown. The 
counterweight assembly 703 is principally intended to balance the weight 
of magazine 150 including product trays 182 since the weight of green 
sheets and protective spacers as may be contained therein at any time will 
be substantially insignificant in comparison. Thus, movement of the 
elevator assembly will require little force and the particular actuator 
chosen is not important to the practice of the invention. However, a 
pneumatic actuator is preferred for ease of control, freedom from 
vibration, reduced wear and contaminant materials. 
The elevator assembly preferably includes a cantilevered shelf 707 affixed 
thereto for supporting a magazine 150. The stationary frame 701 provides 
for mounting of proximity or position sensors 708, preferably of the 
optical or magnetic type which sense a grid of perforations or other 
detectable elements 709' in an element 709 carried by the elevator 
assembly. A pawl or detent engaging a preferably saw-toothed surface or 
edge of element 709 or another element prevents the magazine 150 from 
falling to the level of carousel 120 if power is interrupted. Thus it is 
preferred that the pawl or detent be spring biased into contact with the 
saw-toothed surface and withdrawn only when positively actuated. 
The cantilevered shelf is also preferably provided with a pair of channels 
to engage a flanged bottom of a magazine 150 and securely hold it in a 
precise location during vertical motion. It is also preferred to provide a 
stop plate 711 to further insure correct positioning of a magazine 150, 
particularly when it is moved from carousel 120 to the elevator assembly 
including shelf 707 by operation of the embodiment of the invention 
illustrated in FIGS. 1 and 3. Similarly, it is preferred to provide a 
spring-loaded retractable pawl detent 712 to further secure the magazine 
150 during vertical motion. 
By virtue of the above described magazine transport assembly 160 a magazine 
can be lifted to bring a stack of green sheets, each protected by a spacer 
sheet to a vertical position corresponding to the heads carried by 
rotating head assembly 140. Preferably, as alluded to above, such a stack 
of green sheets is contained in a product tray 182 carried by the magazine 
150 which can be moved from the magazine on tracks 181 to a location 
directly below a head carried by the rotating head assembly. In this way, 
mechanical interference between motion of the heads and motion of a 
magazine 150 is readily avoided. 
The heads 605-608 (FIGS. 1-3 and 6) carried by rotating head assembly 140 
are important to the invention to the extent that they must be suitable 
for securely gripping a green sheet (or other lamina which are to be 
stacked by the invention) while moving it with high precision to another 
location without causing any damage to the edges or surfaces (particularly 
conductive patterns thereon) of the green sheets. For this reason and the 
fact that magnetic and electrostatic pick-up arrangements may not be 
suitable for some features possibly included in modular circuit package 
designs, a vacuum manifold is preferably attached to commercially 
available pneumatic actuators to form the heads for contact with green 
sheets, plates, protective spacer sheets etc. Forces derived from vacuum 
manifolds for pick-up and pneumatic actuators are readily adjusted by air 
pressure supplied thereto and modulated in a well-understood manner to 
provide adequately gentle handling of the green sheets and other 
materials. 
For example, in regard to the actuators, air pressure at about 40 psi. is 
preferably used and, given a green sheet area of about 50 square inches 
and a three-quarter inch piston, limits pressures applied to about eight 
ounces per square inch at the green sheet surface. Variations on the 
design of the vacuum manifolds will be apparent to those skilled in the 
art and should be provided in accordance with the particular functions to 
be achieved by each head. 
From the foregoing, it is seen how green sheets are selected in a desired 
order by vertical movement of a (selected) magazine 150, protective 
spacers removed individually from each green sheet and disposed of and the 
green sheet picked up and transported to an alignment station 602 in 
accordance with path 110. It has also been demonstrated how separator 
plates can be picked up from station 603 and also brought to the alignment 
station 602 for stacking with the green sheets. By virtue of the use of 
separator plates, plural modular circuits can be assembled vertically and 
maintained in that configuration through a sintering process. This process 
provides for equalization and uniformity of compressive forces through the 
stack of modular circuits during the sintering process and also 
facilitates storage and transportation of a greater number of modular 
circuits prior to sintering since they are stacked one upon another. The 
throughput capacity of the sintering presses and other sintering equipment 
is similarly increased. However, the increased height of stacking presents 
another problem which is solved by the invention, as will now be 
described. 
Specifically, if apertures on the green sheets are used for purposes of 
precise registration and alignment on pins (preferably four, corresponding 
to corners of the green sheet) provided on alignment trays during 
stacking, increased stack height requires an increased height of alignment 
pins. As the head 605 brings a green sheet to the alignment station and 
releases it in substantial registration with the alignment pins, the green 
sheet essentially settles on the alignment pins and its motion is 
well-described as free-falling or floating since it is not otherwise 
constrained. 
If the alignment pins are elongated, the likelihood that the green sheet 
will assume a diagonal or sloping orientation on the alignment pins is 
greatly increased. Such an orientation causes forces to be applied to the 
alignment apertures on the green sheet and is likely to cause tearing 
thereof. Further, if the green sheets are not individually pressed 
together as they are assembled, the potential for contamination is 
increased and it is inevitable that air inclusions will result if the 
green sheets are only pressed together as a group. Further, and perhaps 
more importantly, if the green sheets are pressed together from an angled 
orientation, it is inevitable that some wiping motion of one green sheet 
against another will result, having the potential effect of smearing the 
fine pattern of conductive paste on the surface thereof, potentially 
causing massive shorting of conductors and, at a minimum, deforming the 
cross-sectional shapes of the conductors. These potential problems and 
others are solved by the alignment station, similar to that disclosed and 
claimed in the above incorporated, concurrently filed application, 
particularly when taken together with carousel 130 in path 111. 
Specifically, carousel 130, shown in detailed plan view in FIG. 8, performs 
several functions. Most basically, the circumference of carousel 130 
allows for a plurality of assembly trays with alignment pins to be 
provided and to be ready for stacking of green sheets, as needed, to 
provide for continuous production. The diameter of carousel 130 also 
provides for physical separation of the alignment station, where the green 
sheets are stacked, from the operator to reduce the likelihood of 
contamination. After stacking, carousel 130 also returns the stacked 
modules to the operator for removal and transfer to lamination press 
apparatus. 
It should be noted, in this regard, that the size of fixtures 901 is 
determined in accordance with the physical transverse dimensions of a 
green sheet or other lamina and it is preferred to provide for six 
fixtures appropriate to lamina of currently preferred size (e.g. seven to 
eight inches on a side) on carousel 130 to provide suitable latitude for 
operator activity. Larger lamina could then be accommodated most 
inexpensively, if needed, by reducing the number of fixtures 901 on 
carousel 130 to four. Alternatively, and preferably, larger lamina could 
be accommodated at relatively low expense by increasing the diameter and 
circumference of carousel 130 to whatever size is required to hold six 
fittings 901 of corresponding dimensions. 
Further, the fittings 901 for receiving assembly trays allow the operator 
to establish an initial alignment of the assembly trays which is further 
refined at the alignment station 602. Specifically, fittings 901 are 
preferably sized to provide an alignment accuracy of about 0.005 inches 
simply by inserting an assembly tray therein. Alternatively, 
micrometer-like screw adjustments could be provided but are not required. 
By allowing the operator to bring alignment within certain tolerances that 
can be accommodated by the alignment station, the invention can achieve 
extremely precise positioning of the assembly trays. 
When the assembly tray reaches the alignment station, the alignment pins 
are gripped by a template, preferably provided by head 605 or 606, which 
can be placed over the tapered ends of the alignment pins or other 
mechanism and the latter brought to a precise location. Alternatively, 
robotic cams can be used to adjust alignment, as discussed in the 
above-incorporated patent application. The assembly tray is then 
preferably locked in this precise position by application of a vacuum to 
the underside thereof as discussed in the above-incorporated application. 
Fixture aligning pins 906 can also be used for either coarse or fine 
alignment. 
Once precise positioning of an assembly tray is achieved, stacking of green 
sheets can begin. 
The pressing of the green sheets together as each individual green sheet is 
added to the stack is achieved by a frictional linear clutch arrangement 
which is more specifically discussed in the above-incorporated U.S. patent 
application. But will be briefly discussed herein with reference to FIGS. 
9-12 in the interest of completeness. 
Essentially, when the stacking fixture 195 (FIG. 1) is brought to the 
alignment station 602 (FIG. 6), it will preferably have a stacker plate 
902 already fitted over stacking pins 904 by holes sized to readily 
provide of movement of stacker plate 902 thereon. Top cylinder 908 then 
raises plate 910 to engage the alignment fixture 195 at the vertical 
position to which it is brought by the carousel 130 and fine alignment is 
carried out. 
Referring now to FIG. 10, a middle cylinder 920 (omitted for clarity from 
FIG. 9) presses shaft 935 or other suitable linkage upward through a 
linear friction slip clutch 930 which, in turn, raises a platform 945 
(which may be of annular form if needed for clearance from upper cylinder 
908) to raise rods 940 through apertures 950 in plate 910 to lift stacker 
plate 902 to a position near the top (preferably proximate a tapered 
shoulder portion as discussed in the above-incorporated application) of 
alignment pins 904, effectively shortening the pins so that no significant 
diagonal positioning of the green sheet can occur to cause tearing or 
wiping action. The stacking plate is held at this location by friction 
slip clutch 930. 
Then, as the rotating head assembly is rotated, head 605 brings a green 
sheet into substantial registration with the alignment pins 904 with a 
small clearance (preferably about 1/16 inch) above them. As shown in FIG. 
11, the green sheet 1000 is then released and allowed to settle on the 
shoulder of the registration pins at the juncture of cylindrical and 
conical portions thereof, as discussed in the above incorporated patent 
application. The head 605 remains briefly in position above the alignment 
pins (or head 606 brought to that position) while the lower cylinder 960 
raises the upper cylinder 908 and the stacking fixture including the 
alignment pins, as shown in FIG. 12. Head 605 or 606 may be allowed to 
have small horizontal motion to self-align alignment bushings 970 with 
alignment pins 904 during this operation as the alignment pins are raised 
together with the alignment fixture 195. 
The most recently placed green sheet 1000 rises with the alignment pins 
until it contacts head 605 or 606 where it remains in fixed position while 
previously placed green sheets (or stacker plate or a separator plate) in 
the stack are raised against it, pressing all green sheets, separator 
plates and the stacker plate down the alignment pins against the action of 
the friction clutch 930. Thus when lower cylinder 960 is returned to the 
normal position, the most recently placed green sheet 1000 will assume the 
position previously occupied by the previously placed green sheet and the 
protrusion of alignment pins 904 above the stack will be precisely 
maintained. This operation can be repeated at will to the capacity of the 
alignment pins 904. 
As the process is repeated, each subsequently stacked green sheet is evenly 
and gently pressed against a previously stacked green sheet or plate in 
the stack. Further, as each green sheet is added and pressed down by the 
head 605 or 606, support rods 940 will be pressed lower through friction 
clutches 930 by precisely the thickness of the added green sheet, as 
indicated with particular clarity by movement of exemplary piston 980 of 
middle cylinder 920. Thus, tearing of the green sheets by the alignment 
pins and wiping actions between green sheets is avoided while each green 
sheet is pressed against the stack as it is added in order to avoid air 
inclusions and to reduce the possibility of contamination. 
After the required sequence of green sheets has been stacked, a separator 
plate can be added to the stack by head 606 (both preferably under data 
processor control) and the process can be repeated to form another module. 
(Mylar separator sheets are preferably added to the stack before and after 
each separator plate to prevent contact between a lamina and a plate.) It 
should be noted in this regard that plural stacks can be formed on the 
same stacking fixture 195 by separating them with separator plates 
supplied from plate supply station 603. In theory with the alignment 
station arrangement described above, there is no limit to the length of 
the alignment pins and the number of modules which can be assembled on a 
single assembly tray. However, in practice at the present time, it is 
preferred to limit the alignment pin height to about 0.85 inches as an 
incident of current lamination press dimensions and having nothing to do 
with the operation or successful practice of the invention or the 
alignment station thereof. Such a practical and conservative alignment pin 
height can accommodate about five to ten modular circuits of current 
design complexity, allowing a five -to ten-fold reduction in storage space 
and a five- to ten-fold increase on lamination press apparatus throughput. 
By the same token, a five- to ten-fold increase in complexity (in terms of 
number of green sheets required; the number of potential connections 
should increase exponentially) over current designs could be accommodated 
by the invention. 
It should also be appreciated that the invention allows very rapid green 
sheet selection, removal of protective spacers, cleaning of particles 
during transport, registration and pressing of each green sheet as it is 
stacked in very rapid sequence, allowing several modular circuits to be 
assembled with high manufacturing yield in a time comparable to the manual 
alignment and placement of a single green sheet in a stack. Considering 
that the invention provides for continuous production of modular circuits 
and other laminated structures while reducing the likelihood of 
contamination in a much less labor intensive fashion, the throughput of 
the invention together with increased manufacturing yield is far greater 
than could be achieved manually. For purposes of comparison, at the 
present time the invention is capable of stacking one sheet every 6.8 
seconds on a continuous production basis with much increased manufacturing 
yield over manual methods whereas manual placement of a single sheet would 
often exceed one minute. An operator need only use the time for the 
machine to stack 30-50 green sheets and separator plates (a few minutes) 
to remove a completed stack from carousel 130 and to replace the assembly 
tray/stacking fixture 195 with an empty assembly tray. 
In view of the foregoing, it is clearly seen that the invention provides 
for continuous automated production of multi-layered modular circuits 
including selection, cleaning placement and alignment of lamina while 
disposing of protective materials and providing stacking of plural such 
circuits for lamination, increasing efficiency of handling and storage as 
well as the lamination process itself. Manufacturing yield is increased 
and costs of maintaining an adequately clean environment while reducing 
contamination of lamina during the stacking process while reducing 
restriction on the working environment of a reduced number of assembly 
personnel. The apparatus also efficiently provides for accommodation of 
far more complex modular circuit designs than are currently in use while 
providing substantial manufacturing benefits as applied to current 
designs. The apparatus can also be readily and inexpensively modified to 
accommodate green sheets or lamina of any practical size. 
Further, in view of the fact that a job run is generally on the order of 
twenty stacks, each of which can be diced into, for example, nine or 
twelve modular circuit packages, and the capacity of the machine for green 
sheets, separator plates and the like will accommodate production of 
eighty pieces or stacks, it can be seen that four job runs can be 
performed without reloading the machine, thus reducing the possibility of 
contamination to a very low level. When it is considered that a stack of 
lamina for a current modular circuit design will consist of five to ten 
sheets and that a stack, once laminated, will be diced into nine or twelve 
modular circuits, a stacking rate of 6.8 seconds per sheet in continuous 
production translates into an average production of a modular circuit 
every 3 to 7 seconds at extremely high production yield and under the 
control of a single operator. Therefore, it is clear that the invention 
provides for very high volume production particularly when the complexity 
and precision of the modular circuit package is considered. It is also 
worthy of note that while the apparatus according to the invention is 
complex, the tooling cost thereof is only 10%-15% of the tooling required 
to support manual assembly in accordance with known assembly methods. 
While the invention has been described in terms of a single preferred 
embodiment, those skilled in the art will recognize that the invention can 
be practiced with modification within the spirit and scope of the appended 
claims.