Laminator for cut-sheet lamination

Described is a cut-sheet lamination using a laminator for the single or double-sided application of a film cut onto a printed circuit board using heated overlay rollers located opposite to each other in a housing. The printed circuit board and the cut film are fed to the overlay rollers simultaneously in the overlay region. The printed circuit board is led in with input rollers, and the film is pulled off a supply reel and is guided over input rollers to the printed circuit board. A cutting fixture is provided within the region of the input rollers. The cutting fixture cuts the film corresponding to the length of the printed circuit board in accordance with a sensor scan. The cutting fixture is put onto a lever capable of swivel motion. The cutting fixture travels along with the film at the cutting of the film, and the lead-in rollers for the film in the region where the cutting occurs are constructed as suction rollers. This provides continuous through movement of the printed circuit boards through the overlay rollers which reliably avoids damage to the photo-materials there.

FIELD OF THE INVENTION 
The invention concerns a laminator for applying cut film to either one side 
or to both sides of a printed circuit board. 
BACKGROUND OF THE INVENTION 
Laminator equipment is used to apply to one or both sides of a printed 
circuit board a resistive layer using a dry process. For the same purpose, 
wet photoresist material is applied. The circuit board consists of 
polyester material as carrier. The attached photoresist layer is generally 
designated here as film. The film has a protective layer and is stored on 
a supply reel, and after the protective layer is pulled off, the film 
features a sticky underside. After cutting of the film with a cutting 
fixture, the film is pressed onto (laminated) the printed circuit board in 
the presence of pressure and heat using heated laminating rollers. 
It is particularly important that the cut overlay for the printed circuit 
board be accurately and cleanly cut and applied, and especially that the 
film overlay be cut slightly shorter than the printed circuit board. By 
this method, otherwise considerable consumption of material is saved and a 
protruding sticky rim of cut film on the printed circuit board is avoided. 
In the course of further work with a board having a rim of this kind, 
following boards may stick together or the border of the film layer may 
crumble off. Because of the sticky nature of the debris, it is to be 
expected that operational interruptions may occur with this type of 
machinery. Because these debris particles are very sticky, it must be 
expected that they will reach the boards, disturb the subsequent 
photo-illumination process, and damage the conductor trace paths. 
Consequently, the film is always cut shorter than the plate. This also 
results in financial saving of expensive film. 
A laminator for cut-sheet lamination of the described kind is already 
known, especially with cutting the film shorter than the printed circuit 
board. In that device for laminating, the film is positioned at the front 
edge of the printed circuit board, and both are led through the overlay 
rollers together with the printed circuit boards using swiveling feed 
rollers which guide the film in and stretch the film using positioning 
devices. 
In that laminating device, the cutting device moves against the direction 
of the film transport upwards and cuts the film somewhat shorter than the 
printed circuit board. A disadvantage is that a relatively complicated 
construction with many failure-prone parts is needed resulting also in 
high fabrication costs. A further disadvantage of that version is that 
transport of the film and movement of the printed circuit board are 
stopped as the film is cut from the plate which results in the 
disadvantage that, with heated overlay rollers, the rollers come to rest 
against the printed circuit boards which have film already applied, 
resulting in local overheating of the film in the region of the overlay 
rollers. 
SUMMARY OF THE INVENTION 
In order to aid in the understanding of this invention, it can be stated in 
essentially summary form that it is directed to a laminator which has 
suction rollers provided for the transport of the film, which starts with 
the reversing roller at the film supply reel, and for guiding the film to 
the printed circuit board in the region of the overlay rollers between 
which the cutting fixture is guided back and forth. The film transport is 
simplified and performed with precision, especially with different film 
materials. This secure film guiding is retained even if the film is cut 
while moving between suction rollers. The beginning of the film is 
positioned into a starting position to ensure that, when a new printed 
circuit board is fed in, the film is redirected to the beginning of the 
printed circuit board. The cut-off, free end of the film is easily grasped 
by the following suction roller after cutting of the film, and the film is 
put into an initial position in the region of the printed circuit board. 
It is, therefore, a purpose and advantage of this invention to provide a 
laminator such that, with few and simple means, good operational integrity 
at small fabrication cost can be obtained and the printed circuit boards 
are capable of running through the overlay rollers continuously without 
being damaged. 
It is another purpose and advantage of this invention to provide a cutting 
device which moves along with the film in its transport direction, 
depending on the values of the sensor signals which correspond to the 
length of the printed circuit board, as soon as, depending upon the length 
of the printed circuit board, the film length to be cut is established. 
It is another purpose and advantage of this invention to provide a 
high-speed laminator wherein the transport speed of the film is 
approximately between 0.25 and 2.5 meter/minute. With a cutting duration 
of the cutting fixture of approximately 1 second, the film can be cut 
without difficultly while it is moving, especially when preselecting a 
shorter length than the corresponding length of the printed circuit board. 
The laminator avoids requiring positioning fixtures, such as fixtures going 
back and forth; and the laminator operates with the printed circuit boards 
running through the overlay rollers continuously, while the film is fed 
intermittently but is cut continuously during the film transport. High 
operational integrity and exact film guiding are obtained at low 
fabrication cost with few and simple means. In the preferred version, the 
lever of the cutting fixture is on its front side implemented as a cog 
rail, which is engaged to a motor-driven pinion wheel. The cutting fixture 
is mounted on a carriage having a motor and another driven pinion wheel 
which is engaged with a cog rail that is perpendicular to the film. A 
pneumatic drive for the running carriage may be used instead of the motor. 
It is advantageous if the cutting fixture has single motor or pneumatically 
driven oscillating knives which rest under spring tension against a 
cutting edge, with the film being guided on top of the cutting edge. In 
the preferred version, within the region of the run-along path of the 
cutting fixture, there is a first suction roller on top and a second 
suction roller below with sheet metal guides in the region of guiding the 
film at the second suction roller. In an advantageous version, the first 
suction roller is preceded by a reversal roller for the film, and the 
suction region of the first and second suction rollers is made adjustable 
according to the angles by moving the suction rollers and/or the reversal 
roller and the sheet metal guides. 
In a preferred implementation example, in the area of film guiding, the 
suction rollers, the reversal rollers, or in the area of the roller pairs, 
a rotational pulse emitter is located. The pulse emitter in connection 
with a pulse selector switch puts out pulses from the sensors according to 
the length of the printed circuit board. Thereafter, emission of the 
pulses and the drive of the cutting fixture is started, and a motor and 
electromagnetic clutch and the pinion wheel for initiating the swivel 
motion of the cutting fixture is started synchronized to the transport 
speed of the film. 
The invention is further described using drawings which depict only one 
possible implementation of the invention. 
In the following, the invention is further described using drawings which 
depict only one possible implementation of the invention. With this, 
further features and advantages of the invention which are essential to 
the invention, emerge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The laminator shown in FIG. 1 consists of a housing 1 which contains a 
feed-in device 2 to transport the printed circuit board 37 in the 
direction of the arrow 3 into the housing 1, according to FIG. 1 and as 
seen in FIG. 2 from the opposite side. The printed circuit board 37 first 
reaches the roller gap of a first roller pair 4 to obtain guiding of the 
plate 37. Afterwards, the not-yet overlayed printed circuit board or plate 
37 arrives at the roller gap of a second roller pair 5, with the drive of 
the first roller pair 4 being dependent on the drive of the second roller 
pair 5 such that it is always provided that the plates 37 are led into the 
overlay region 6 with an accurately defined distance or gap, depending on 
the plate length despite the fact that initially the printed circuit 
boards 37 are fed in laying in a stack. 
At the inputting of the plate 37, it is grasped by the first pull-in roller 
pair 4 and transported somewhat slower than with the following second 
roller pair 5. As the board 37 is then gripped by the roller pair 5, the 
first roller pair 4 runs faster (free run) until the end of the board is 
reached. As plate 37 leaves the first roller pair 4, this roller pair 4 
turns back by the amount of the speed differential and turns slower 
establishing thereby the necessary distance (gap) from the preceding plate 
37. The plates are placed stack-on-stack onto the input device 2 where, 
however, to differentiate between the individual plate dimensions, the two 
input roller pairs 4, 5 do not turn synchronously. The first roller pair 4 
is equipped with coasting and a backspace element. By this, a defined gap 
between the entered plates is established independent of the length of the 
printed circuit plates. 
Board 37 arrives after further input travel through the second roller pair 
5 in the region of a top-mounted suction roller 7, which serves for 
leading in of the film 10. Board 37 is then pushed or pulled into the 
overlay region 6 by the overlay rollers 15 where the film 10 has come from 
above into the contacting area 36 to rest with its sticky surface at the 
beginning area of board 37. With further pulling in of board 37 together 
with the applied film 10 into the press-on region of the overlay rollers 
15, the film 10 is then laminated onto the board 37 by heat and pressure. 
Depending upon the length of board 37, as determined prior within the 
input region between roller pairs 4 and 5 using sensors 20, 21, cutting of 
the film 10 is accomplished within the region between suction rollers 7 and 
13 using a cutting fixture 14, which moves along with the film 10. 
A rotation measuring device within the region of the film input counts 
pulses according to plate length. After the count is completed, or 
preferably somewhat earlier as determined by a preselect switch, the 
pinion wheel 22 at the cog rail 23 is started over a run-along clutch, 
which makes the cutting fixture 14 move along with the film 10. At the 
same time, drive 28 of the cutting knife 27 is started. After completion 
of starting of drive 28, the film is cut prior to reaching suction roller 
7. After the cut is completed, the cutting fixture traverses back into the 
rest position. 
The sensors 20, 21 consist of a fiber-optical recognition system where the 
beginning or end of a printed circuit board 37 is recognized using two 
separate dual sense heads. In connection with scanning of the printed 
circuit board, a rotation measuring pulse emitter with, for example, 1,000 
pulses/revolution is provided in the region of the film input or at the 
pull-in roller pair, which makes a resolution of less than 0.1 millimeter 
possible. At the exit of the overlay rollers 15, the printed circuit board 
37 is then transferred out by the pull-out roller pair 16, where additional 
cold laminating pressure is preformed to the output table 17. Considering 
synchronization of plate input and film feed, first the printed circuit 
board 37 is pulled in by roller pairs 4 and 5, where the beginning of 
printed circuit board 37 passes the sight gate to signal the front edge of 
the board at sensor 21 immediately behind the roller pair 5, which gives 
the signal to the rotational pulse emitter to count off a certain number 
(A) of pulses for moving (within the region of the suction rollers 7, 13) 
prior cut-off, free end of the film 10 from a reference position to the 
contact region 36. The printed circuit board and the film are then grasped 
by the overlay rollers 15 within the contact area 36 and pulled in. The 
plate end passes light gate 20. With this, the pulse counter is started. 
After a number of pulses (B) corresponding to the preselected counter 
setting is run off, the cutting fixture 14 is started and cuts the film 
while it is in motion. 
As the cutting process is executed, again a constant number of pulses (C) 
is put to work, which brings the film into an always constant initial 
position closely behind the suction roller 7. The pulse count (A) of the 
film advance after the front edge of the printed circuit board has passed 
the sensor 21 influences the distance from the board edge of the edge of 
the film, which will be applied. The pulse number (A) can be preselected 
by a decade switch (e.g., for 1 to 10 millimeter distance from edge of 
film to edge of board plate). After the pulse count is reached, the 
suction rollers 7, 13 are engaged and transport the film 10 in the 
direction to the circuit board 37 synchronously with the motion of the 
circuit board 37 to the contact region 36, where film and circuitboard are 
grasped by the overlay rollers 15. The film 10 is thereby correctly 
positioned at one or both sides to be cemented by the overlay rollers 15. 
The overlay rollers may be heated or may be cold. The pressure of the 
rollers is pneumatic, and the pressure as well as the roller gap is 
continuously adjustable. As the end of the printed circuit board 37 
reaches the light gate of the sensor 20 after the first pull-in roller 
pair, a pulse count (B), which may also be preselected, is put to work 
analogous to the start process. After reaching the pulse count, a further 
clutch (not shown here) is activated, which is provided for the 
synchronous transport of the whole cutting fixture 14 in parallel to the 
film in its lengthwise direction. At the same moment, drive 28 located on 
the cutting fixture is started, with the drive requiring less than a 
second for cutting the film 10 in the perpendicular direction to itself. 
After cutting of the film with the cutting knife 26 by moving a sled 29, as 
shown in FIG. 3a, and after the cutting knife 27 has reached the other side 
of the film, within 15 milliseconds the whole cutting fixture 14 is 
clutched out again and pivoted back to its initial position. The suction 
rollers 7, 13 move the film on until a preselected pulse count (C) that 
was started with the cutting process is reached. This pulse count (c) 
corresponds to the distance between the cutting edge and suction roller 7 
in front of the overlay rollers 15 (initial position of the film). With 
pull-in of an additional printed circuit board 37, the film 10 is pushed, 
started by the signal from sensor 21, from its initial position moving 
synchronously with the printed circuit board 37 as far as the contact 
region 36. The single or both-sided overlayed board 37 is removed from the 
machinery by the following pull-out roller pair 16 and over a run-out table 
17. With this system, continuous laminating of board 37 independent of its 
length dimension is possible; i.e., the board 37 run without stopping 
through the overlay rollers 15. 
Film guiding in connection with the cutting process considering the 
construction aspects of the run-along cutting fixture is further described 
as follows. First, it is pointed out that the overlay process for the 
printed circuit board with a film from the top side or the bottom side of 
the board 37 are identical. Therefore, for reasons of simplicity, only the 
film input from above with the cutting device 14 and the laminating are 
described further. The film input from above consists of FIG. 1 of the 
supply reel 8 in the vicinity of which a pull-off roller 9 is located, as 
shown in FIGS. 1 and 2. This pull-off roller 9 winds up the protective 
film 11, which is pulled off of the film 10 within the region of the 
reversal roller 12. The uncovered film 10 reaches with its sticky 
underside, which is on the other side of suction roller 13, via suction 
roller 13 the region of cutting fixture 14 and moves thereover a support 
plate 33 of the cutting fixture and continues on into the area of suction 
roller 7. The film is, therefore, held firm in the vicinity of reversal 
roller 12 by suction rollers 7 and 13. The reversal roller 12 is 
implemented as a rubber roller, while rollers 7, 13 have suction 
construction. Responding to the pulse controlled drive between the 
reversal roller 12 and the rollers 7, 13, the film is herewith led to the 
board 37 at the contact region 36 in an intermittent manner, while the 
boards 37 and the accompanying film run through the overlay region 6 in a 
continuous manner. The cutting fixture 14 which follows the motion of the 
film in the transport direction, its function being described hereinafter, 
is located between the suction rollers 7 and 13. 
According to FIGS. 2, 3 and 3a, the whole cutting fixture 14 is arranged in 
an angular region between suction rollers 7, 13 such that it can swivel in 
pivot direction 26. Cutting fixture 14 moves along with the film 10 
whenever, at the completion of pulse count (B), the film has to be cut. 
There is a preselector switch provided to limit the pulse count (B) to 
enable cutting the film shorter than the length of the plate. With another 
preselect switch, the pulse count (A) can also be limited. After the sensor 
20, 21 recognizes the beginning or the end of a printed circuit board 37, a 
pulse count (A) or (B), which can be adjusted using separate preselect 
switches, is put to work. The length of the pulse counts (A or B) can be 
chosen arbitrarily using a freely programmable controller. A pulse 
emitter, in connection with a preselector switch, is provided within the 
film-guiding region; e.g., at the suction rollers 7 or 13, which, after 
reaching a predetermined pulse count, starts pinion wheel 22 and drive 28 
causing the film 10 to be cut by the cutting fixture 14 after a short run. 
After this, the cutting fixture 14 swivels back within a short time period. 
Accordingly, in connection with a preselect switch, the drive 28 of the 
rotating knife 27 is eventually started. After the start of pinion wheel 
22, the cutting fixture 14 pivots in the traversing direction 26, and the 
film 10 is cut while in motion between suction rollers 7 and 13. As it is 
advantageous here, the pull-in motion of the printed circuit boards 37 
together with the film 10 moving along is not interrupted in the region of 
the overlay rollers 15, so that overheating of the film 10 on single points 
of the printed circuit board 37, which may influence the consecutive 
treatment procedure of the photo-overlayed printed circuit board 
unfavorably, is avoided. The total cutting fixture 14 is herewith located 
on the free end of arm 24, which is fastened capable of swiveling to 
housing 1 at the pivot point 25. The swivel motion of the arm 24 is caused 
by the fact that there is a cog rail 23 firmly attached to the lower end of 
the cutting fixture 14, which engages to a correspondingly rotating pinion 
wheel which is driven and has a fixed location in the housing. The drive 
and the cog rail are constructed in such a way that, at the pressure 
support plate 33, a speed synchronous to the film is obtained. Pinion 
wheel 22 is started over an electromagnetic clutch by a motor (not shown) 
and also pivots the cog rail 23 into cog rail position 23'. The cutting 
fixture 14 is started simultaneously with the start of pivoting motion in 
traversing direction 26. 
The cutting process is, according to FIG. 3a, initiated by shifting the 
sled 29 with the cutting knives 27' simultaneously with the start of drive 
motor 28 for the cutting knives 27. During the time pinion wheel 22 moves 
cog rail 23 with the cutting fixture 14, as shown in FIGS. 2 and 3, sled 
29 leads the cutting knife 27' across the film 10 to cut it, as shown in 
FIG. 3a. According to FIG. 3a, a second cog rail 31 is provided which is 
engaged to a pinion wheel on motor 30 to move the sled 29, including the 
drive 28 with the rotating knives 27, perpendicularly across film 10 in 
the direction of arrow 32. The cutting knives 27 rest here spring-loaded 
against a support plate 33. Because of the choice of using rotating 
cutting knives 27, excellent cutting quality is achieved. 
Because of the intermittent feed-in of the film, it is now possible to 
assign film cuts of different lengths to the respective printed circuit 
board 37 of the right size. Depending upon the adjustment of the 
equipment, the film cuts may be shorter than the printed circuit boards, 
which brings about the advantages described hereinabove. The film cuts, 
however, may also be the same length as the printed circuit boards. 
Furthermore, according to FIG. 2, sheet metal guides 18, 19 are provided 
for feeding the film from the initial position appropriately to the 
overlay gap at the overlay rollers 15. FIG. 4 shows schematically the 
drive of the film 10 in the region of the suction rollers 7, 13. Here, it 
can be recognized that the upper suction roller 13 holds the film 10 
within a region of angle 35, while lower suction roller 7 contacts the 
film 10 in a substantially smaller angular range 34. By the intermittent 
drive of these two suction rollers 7, 13, the film is advanced in an exact 
manner and is held extremely well, especially during cutting, and it cannot 
free itself accidentally from these suction rollers thereby making it 
possible to apply the film with the highest accuracy to the printed 
circuit board 37. The choice of both angles 34, 35 are dependent on the 
weight of the film, the strength of the film, and the transport speed. The 
range and the position of angles 34, 35 is adjustable specifically by 
changing the position of the suction rollers 7, 13 also possible in 
connection with a shift in the location of the reversal roller 12. 
Furthermore, the guiding range of the sheet metal guides 18, 19 can also 
be changed and additional drums and reversal rollers may be installed 
within the region of the film-guiding range for changing the angular range 
of the angles 34, 35. 
In summary, there is, therefore, a cut-sheet lamination with continuous 
operation of the boards 37 to be overlayed, which can be entered 
stack-on-stack into the input device 2. Boards of different lengths with 
an arbitrary mix can be entered in any sequence. The film is cut shorter 
than the boards, and the difference can be preset. There is a 
lamination-free space at the beginning/end of the printed circuit board 
that can be preselected independent from the length of the plates. Through 
rotation-segment-suction according to the invention, the film is brought 
into position free of tension over the suction rollers 7, 13, which makes 
it possible to achieve exact guiding and cutting of the film by simple 
means. The rotation-segment-suction according to the invention permits a 
very simple construction, because back-and-forth moving components are not 
used. The film is uniformly driven and can be synchronized very easily 
using an electromagnetic clutch where switching durations of less than 15 
milliseconds can be achieved. By this means, the use of expensive servo or 
stepper motors is not necessary. For the total drive, a DC-motor with 
toothed belt drive is provided. With the construction of the laminator 
according to the invention, a wear and tear resistant total solution has 
been provided which has the advantage of long equipment life without 
further adjustment work. 
The subject of the present invention is not only the subject of each 
individual claim alone, but also the combination of the individual patent 
claims in relation to each other. All the data and features disclosed in 
the write-up, including the summary and especially the spatial layouts 
shown in the drawings, are claimed to be important parts of the invention 
as far as they are new in themselves or in combination relative to the 
status of technology.