WO1988004981A1

WO1988004981A1 - Process and device for removing protective foils

Info

Publication number: WO1988004981A1
Application number: PCT/EP1987/000824
Authority: WO
Inventors: Christian Schmid
Original assignee: Gerbr. Schmid Gmbh & Co.; Dieter C. Schmid Gmbh
Priority date: 1987-01-10
Filing date: 1987-12-24
Publication date: 1988-07-14
Also published as: DE3700615A1

Abstract

In order to improve a process and device for removing a protective foil from a support, in particular a printed circuit board coated with a laminated photopolymer layer, by means of a stripping foil that can be linked to the protective foil, that is placed on the protective foil and that removes the protective foil by moving it relative to the support, in such a manner that any kind of foil can be removed by machine without damaging the photopolymer, a partial zone of the protective foil is welded to the stripping foil.

Description

Method and device for removing a protective film

The invention relates to a method for peeling off a protective film from a carrier, in particular from a printed circuit board with a laminated photopolymer layer, by means of a peelable film which can be connected to the protective film and which is placed on the protective film and by means of which the protective film is peeled off by a movement towards the carrier.

The invention further relates to a device for peeling off a protective film from a carrier with a holder for the carrier and a device for placing a peelable film that can be connected to the protective film on the protective film and for removing the peelable film with the protective film from the carrier by a relative movement between the carrier and protective film.

When manufacturing printed circuit boards for electrical circuits, the conductor tracks of these printed circuit boards are there produced by coating a printed circuit board with a photopolymer which, after exposure to a corresponding mask, forms an unassailable layer for the etching solution either at the exposed or the unexposed areas, so that when the printed circuit board is treated with the etching solution, the covered areas of the metal layer are formed stay while the other areas are removed.

To protect the Fotop polymer layer, it is necessary to cover it on its free surface with a transparent protective film, so that an exposure process can be carried out with the protective film on top. When coating the circuit board, the protective film is laminated together with the photopolymer layer as a unit. However, the protective film must be removed from the photopolymer layer before development. The photopolymer layer and the protective film are extremely thin, in the range of a few μm, and it is therefore difficult to grip and remove the protective film lying on the photopolymer layer.

Above all, it has so far only been possible in special cases to automatically remove the protective film. The previously known methods only work with very specific photo polymer layers and very specific foils.

One of these methods consists in pressing glasses into the protective film in the area of their front edge and on blow the resulting lift off with a strong air stream so that the protective film is blown off the photopolymer layer.

In another method, it is known to grip this protective film in the area of a corner with a pair of pliers and to pull it off diagonally to the carrier by moving the pliers.

The two methods described above have the disadvantage that there is a risk that photopolymer particles can be detached by the described procedure and fall or be blown uncontrollably onto the areas without protective film, which during development cause problems, in particular interruptions and short-circuits of the conductor tracks and thus too lead useless circuit boards.

Finally, from DOS 27 47 265 a method and a device is known in which an adhesive tape is unwound from a supply roll and rolled onto the protective film and then moved away from it again, so that when the adhesion between the adhesive tape and the protective film is greater is that between the protective film and the photopolymer the protective film is peeled off by the adhesive tape.

However, the rule of thumb is that an adhesive tape must always be found that adheres more strongly to the protective film than to the photopolymer itself. Furthermore, problems arise with the fact that the first lifting the front edge of the protective film off the

Photopolymer requires a far greater force than that

Lifting off a partially released protective film from the photopolymer so that the adhesive force between the

Tape and the protective film must be several times larger than that between the protective film and the photopolymer.

Such tapes are very expensive. Finally, the protective film should be removed as quickly as possible, so that an adhesive must be found which sets quickly in fractions of a second. This method therefore depends essentially on the adhesive force between the tape and the protective film, which immediately results in the fact that this cannot be used universally with different types of protective films and photopolymers.

Based on this prior art, the invention has for its object to improve a method of the generic type such that eir. mechanical peeling is possible regardless of the type of protective film, without causing damage to the photopolymer.

This object is achieved according to the invention in a method of the type described in the introduction in that the protective film is welded to the release film with a partial area.

The welding of the two foils to one another has the advantage that, with all types of protective foils, firm connection between these and the peelable film can be produced. In addition, the removal of the protective film in the method according to the invention has the advantage that it is carried out extremely gently, so that damage to the photopolymer layer can generally be ruled out.

As already described at the beginning, the protective film is only a few 10 μm, generally 25 μm thick, so that welding such thin films is particularly problematic. According to the current state of knowledge, it was even assumed that such thin films could not be reproducibly welded to one another, since it is very likely that in many cases no weld seam will be created, but holes will be melted into the film. For this reason, it has so far been refrained from welding the protective film to the release film. A significant improvement in the reproducibility can be achieved in that the peel-off film and the protective film underneath are pressed against the carrier during welding. As a result, good heat conduction between the protective film and the thin photopolymer layer and the underlying metallic layer of the printed circuit board is produced, so that the protective film is rarely cooled during welding of the photopolymer layer and thereby the melting of holes can also be prevented.

According to the present invention, it is sufficient to weld the protective film to the release film only with a partial area, since only the requirement stands to produce such a stable weld that the protective film can be removed by the peel-off film. It would therefore be theoretically possible to place the weld seam in any part of the release film. However, since the protective film adheres very firmly to the photopolymer layer and thus the first detachment from the photopolymer layer requires a very large tensile force, it is advantageous if the partial area is formed by part of an edge region of the protective film, so that the first pull when the protective film is removed this acts on an edge area which can be detached with the least force in relation to the central area. Furthermore, it should also be taken into account that welding the peel-off film to the protective film also slightly heats the underlying photopolymer layer, so that when the peel-off film is welded to the protective film, damage to the exposed photopolymer layer and thus unusability of the central part is achieved etching circuit board could come later. This risk is less with the edge area, since it is not difficult to design the lay-out in such a way that the area of the printed circuit board below the edge area to be welded does not have to be provided with conductor tracks.

For detaching the protective film from the photopolymer layer, it is most advantageous if the edge region is formed by the outer edge of the protective film running along a side edge. In this case, the outer edge of the protective film is welded to the peel-off film, so that the first tensile force when peeling off acts directly in this edge region, in which an easy detachment of the protective film from the photopolymer layer is possible.

In an advantageous embodiment of the method it is provided that the protective film is welded to the release film at least in sections along its side edge.

In one embodiment, the detachment can take place in that the first train acts simultaneously on the entire side edge as a whole.

On the other hand, in the case of protective foils which are very difficult to detach, it is advantageous if the first train, beginning at one end of a side edge, spreads along this side edge with a time delay to the other end thereof.

However, since difficulties could also arise when the side edge is welded in sections, it is easiest if the protective film is welded to the release film along one side edge, so that the first tensile force acts on the entire side edge

To weld the protective film along a side edge, it is also possible for the protective film to be welded to the peel-off film in the area of a corner, since it is particularly easy in the area of a corner to detach the protective film from the underlying photopolymer layer, so that only a very small area the protective film must be welded to the release film. To pull it off, however, the protective film would then have to be pulled diagonally to the circuit board. This would be conceivable, for example, in that the printed circuit board is moved forward parallel to a side edge forming the corner and the pull-off film exerts a pull on the protective film at an angle to the forward movement of the printed circuit board; but it would also be possible to move the circuit board forward in the direction of the bisector of the side edges forming the corner, so that the release film could exert a pulling force in the opposite direction to the forward movement of the circuit board.

As already explained above, very thin foils are extremely difficult to weld, since there is always the risk that no weld seam is created, but that holes are melted in the foil. For this reason, it is advantageous if a film made of material with a melting point similar to that of the protective film is used as the peel-off film, since there is no longer any risk that one of the films will already melt while the other film is still completely firm.

The simplest way to achieve the above requirement is to use a film made of the same material as the protective film as the release film.

Furthermore, when welding very thin foils, it is advantageous if a foil with a comparable thickness to the protective foil is used as the peeling foil, since the heat conduction takes place in the same way as seen over the thickness of the foils, so that the mutually abutting ones fuse well Areas is guaranteed.

Especially when a polyester film is used as the protective film, there is the problem that the peeled off Protective films can only be packed very bulky, since it is not possible to bend these films and thus permanently deform them for tight packaging. For this reason, it is advantageous if the peeled-off protective film is wound up with the peeled-off film, since this is the simplest method of achieving the tightest possible packing of the removed protective film.

In order to keep the tensile force required for detaching the protective film on the connection between the peel-off film and protective film as low as possible, it is provided in a preferred embodiment of the invention that the removed protective film includes an angle of <160 ° with the protective film still adhering to the carrier, which means that the deducted

Protective film with the free polymer layer encloses an angle of> 20 °. This is necessary so that the pulling force on the peel-off films is not too great. However, it is far more advantageous if the protective film removed forms an angle of <90 ° with the protective film adhering to the carrier, so that the force acting on the removed protective film points in the pulling direction.

The lowest release force is required if the removed protective film forms an acute angle of, for example, <20 ° with the protective film still adhering to the carrier, since the protective film then has a very strong curvature in its detachable area, as a result of which the adhesive forces between the two are overcome very quickly Protective film and the photo polymer layer is accessible. As an alternative to the process examples described above, in which the removed protective film runs at an angle to the protective film still adhering to the carrier, in an improved embodiment it is provided that the protective film adhering to the carrier is pulled off tangentially along a curved path, so that the protective film is lifted off the carrier very slowly. This has great advantages, in particular when the protective film is initially pulled off, since this method causes the protective film to be lifted off the support very slowly and thus results in a low load on the connection between the protective film and the release film.

It has proven to be particularly advantageous if the protective film adhering to the carrier is pulled off tangentially along the curved path at the beginning of the peeling process and then at an angle to the carrier. This initially takes advantage of the slow pulling along the curved path when the protective film is initially removed and then more efficient removal can take place in that the removed protective film forms an angle with respect to the protective film adhering to the carrier, which does not place any additional load on the connection between the Peel off film and the protective film, since once the protective film is removed, the forces that occur are lower. In addition, after the initial detachment, the welded connection between the peel-off film and the protective film has cooled and can therefore withstand greater loads.

Since the protective film is generally a very expensive film because of the required properties and the peel-off film should be as similar as possible, a very expensive one would necessarily have to be Use peel-off film. For this reason, it is advantageous if a protective film originating from a previous removal process is used as the release film. This also automatically solves all problems with regard to the requirements regarding the melting point and the thickness of the two foils to be welded together.

In general, the circuit boards are coated on both sides with protective films, so that a particularly economical process can be seen in the fact that the protective films are removed from both sides of the carrier at the same time

Furthermore, it is an object of the invention to provide an apparatus for performing the method.

This object is achieved according to the invention in a device according to the type described at the outset in that a device which attaches the release film to the protective film and welds it to one another is provided.

The device according to the invention has the advantage that it allows the production of a welded connection between the protective film and the release film with the advantages already mentioned above.

In order to be able to establish a good connection between the pull-off film and the protective film during welding, it is advantageous if the welding device and the carrier can be advanced in the direction of one another, it being irrelevant whether the carrier is directed in the direction of the welding device or the welding device in Are designed to be delivered to the carrier. Furthermore, as already described at the beginning, when welding very thin foils there is the problem that reproducible welded connections are produced and that, above all, holes are not melted into the foils instead of producing a weld seam. For this purpose, it is particularly necessary in the case of the thin foils to dissipate the heat generated during welding very quickly, so that it is advantageous if the peel-off foil can be pressed against the protective foil and the latter against the carrier with an adjustable force by the welding device in a welding position, so that the force can be selected so that, on the one hand, good heat dissipation from the protective film to the carrier takes place and, on the other hand, the force on the peel-off film and protective film is not so great that the melting film material immediately runs away to the side of the welding device and therefore no weld seam with sufficient strength arises.

Already in the context of the task mentioned at the beginning, it is mentioned that the device according to the invention should also be suitable for working with different protective and peel-off films. For this reason, it is advantageous if a welding temperature of the welding device can be set so that it can be adapted to the melting temperature of the protective and peeling films used.

Furthermore, it is also advantageous if a welding time can also be set, so that overall the force on the foils to be welded to one another, the welding temperature and also the welding time can be adapted to the respective circumstances. A wide variety of welding devices can be considered in the context of the solution according to the invention. For example, if fast welded connections are to be made, it is advantageous to use a laser to heat up the peel-off film to be connected and the protective film.

With mechanical welding devices, it is conceivable, for example, to drive along the weld seam with a hot roller or a hot stamp in order to produce the connection.

A particularly simple solution, which works with sufficient speed, provides that the welding device comprises welding jaws.

Since a force must be exerted on the peel-off film when the protective film is peeled off and the peel-off film must at least be held in place, it is advantageous if a removal device is provided for the peel-off film and the protective film welded to it, with which the peeled-off film pieces can be removed.

An extremely advantageous tight packing of the peeled film pieces is possible if the removal device comprises a winding device for the peeling film with the welded-on protective film.

The device described so far leaves open whether it is a device that is suitable for individual printed circuit boards or a device that is suitable for an automatic removal process. Since the manufacture of printed circuit boards is generally an ongoing process in which a large number of successive printed circuit boards have to be processed, a device suitable for this purpose provides that the holder is a transport device for a preliminary is a push track on which the carrier can be transported.

In particular in the embodiment of the device according to the invention described above, which is suitable for automatically removing the protective films, it must be ensured that the partial areas of the protective film to be welded to the release film are always the same. For this reason, it is advantageous if a positioning device is provided, by means of which the carrier and the welding device can be brought into a predeterminable welding position relative to one another in order to weld the protective film to the release film.

This would be possible, for example, by providing stop means for the carrier, which however presupposes that the photopolymer layer with its protective film is always laminated onto the carrier at the same position relative to its side edges. However, since this can generally only be ensured with great effort, it is provided in a preferred exemplary embodiment that the positioning device comprises sensors for detecting the protective film.

As has already been explained in detail in connection with the method according to the invention, it is advantageous if an edge region of the protective film is welded to the release film. For this reason, it is also advantageous if the sensors respond to side edges of the protective film, so that the side edges of the protective film can be detected directly. Even if the carrier is positioned relative to the welding device by means of sensors, it would also still be possible to ensure the exact position of the carrier, for example, by pivoting and adjustable stop means. However, since the carrier can already be moved into a defined position by the transport device, it is advantageous if the positioning device comprises a device for interrupting a feed movement of the transport device, so that the positioning of the carrier takes place by switching off the feed movement.

In a particularly preferred embodiment it is provided that in the welding position a welding active surface of the welding device both overlaps an edge area of the protective film to be welded with the peel-off film and also protrudes outwards over this edge area of the protective film, so that it is ensured that the foremost edge of the protective film is welded directly to the peel-off film and the force acting on the protective film upon first detachment acts directly on the edge thereof, so that detachment of the protective film from the polymer layer is possible with a small force on the peel-off film.

Even when using a positioning device, positioning inaccuracies can result due to the path and time resolution of the positioning device. If it is to be ensured that even slight positioning inaccuracies are to be compensated for, it is advantageous if the side edge of the protective film is in the welding position is a central region of an active welding surface of the welding device, so that the side edge is always overlapped by the active welding surface in the event of small positioning errors.

In one embodiment of the device according to the invention, which has a pushing track, it is advantageously provided that the welding device extends over the entire width of the feeding track, so that welding of the film to the peel-off film is possible for all carriers that can be transported on the feed track.

So that the peel-off film assumes a defined position when it is welded to the protective film and in particular also covers the respective welding device in the desired manner, it is advantageous if devices for holding a part of the peel-off film to be welded to the protective film are provided.

Since only the portion of the pull-off film covering the welding device is important, these devices should be as close as possible to the welding jaws, so that it is advantageous if the devices for holding the pull-off film are arranged on the side of the welding device.

The devices for holding the peel-off film can be of any design. For example, it is possible to use a clamping device for this. A far more elegant solution, however, provides that the facilities for Holding the peel-off film are suction openings through which the peel-off film is sucked in and thereby held.

The problem with these devices for holding the peel-off film is that the peel-off film does not automatically contact them. For this reason, it is expedient to provide a device for applying the peel-off film to the devices for holding the peel-off film.

In order for a position of the detachment area to be definable, in one embodiment a detachment guide element is provided, around which the peel-off film is guided, so that the detachment area of the protective film is also defined by the position of the detachment guide element.

With this detachment guide element, an angle between the detached protective film and the carrier can also be determined in a simple manner in that the detachment guide element and the carrier can be moved towards one another. All types of linear drives, in particular also pneumatic drives, are conceivable for this.

A particularly compact exemplary embodiment of the device according to the invention provides that the welding device is integrated in the detachment guide element on its side facing the carrier, whereby the use of separate actuating devices for feeding the detachment guide element and the welding device in the direction of the carrier is also eliminated.

Furthermore, it is particularly advantageous in the case of exemplary embodiments with a feed path if the detaching guide element extends transversely over the feed path. The detachment guide element can be arranged in a wide variety of ways. For example, it is conceivable that the detachment guide element is merely a fixed detachment shoe, around which the peel-off film is guided. As an alternative to this, however, it is advantageous if the detachment guide element can be rotated, in order to load the weld seam with the lowest possible forces, in particular at least when the protective film is initially detached.

A particularly preferred exemplary embodiment provides in this connection that the detachment guide element can be rotated between a welding position and a peel-off film application position, so that initially the detachment guide element is rotated when it is pulled off and this then remains in the peel-off film application position and then only acts as a deflection element.

In the same way as the welding device, it is also possible to integrate the devices for holding the protective film in the detachment guide element, so that in a particularly preferred embodiment the detachment guide element is provided with devices for holding a part of the release film to be welded to the protective film.

The arrangement is advantageously chosen so that the devices for holding the release film are arranged on a side of the detaching guide element facing the carrier. The device for applying the peel-off film to the devices for holding the same can be designed in a wide variety of ways. For example, it is conceivable to design these foils as contact rails, which are actuated by pivoting devices and paint over at least one surface area of the detaching guide element and thereby apply the peel-off foil to the latter. However, a device has proven to be more advantageous in which a pull-off film guide leading to the detaching guide element is provided for applying the pull-off film to the devices for holding the same. This guide can be designed, for example, in the manner of a guide shaft or, for example, also in the manner of a double belt drive, between which the release film is guided.

Furthermore, it has also proven to be particularly useful for monitoring the peeling process if the peeling film device has a sensor for detecting the peeling film.

In all of the previously described exemplary embodiments of the device according to the invention, it is not specified how the release film should look like. It is also generally assumed that the peel-off film and the protective film can be two different films. However, it is particularly simple and advantageous if the peel-off film is the peeled-off protective film from a previous peel-off process, since this eliminates the need to provide a separate peel-off film. In the context of the solution according to the invention, it has proven to be particularly advantageous if a weld seam cooling device is provided, since this creates the possibility of cooling the weld seam in a defined manner, so that it can be subjected to high forces as quickly as possible, which in turn allows the removal process to be carried out as quickly as possible perform.

Further features and advantages of the method according to the invention and the device according to the invention are the subject of the following description and the drawing of an exemplary embodiment. The drawing shows:

Fig. 1 is a perspective view of a

Embodiment of the performance according to the invention;

2 shows a section through the device according to FIG. 1 along line 2-2 in a process stage before a protective film is welded to a release film;

3 shows a section corresponding to FIG. 2 when the protective film is welded to the release film;

Fig. 4 is a section corresponding to Figure 2 and 5 ei.nem peeling off the protective film.

Fig. 6 shows a section corresponding to FIG. 2 shortly before the end of the pulling and

Fig. 7 shows a section corresponding to FIG. 2

Finish removing the protective film. 8 shows a section similar to FIG. 2 of a second exemplary embodiment;

9 shows a section similar to FIG. 8 in the starting position;

10 shows a section similar to FIG. 8 in the stage of film feeding;

FIG. 11 shows a section similar to FIG. 8 with the peel-off film applied to a detaching roller;

FIG. 12 shows a section similar to FIG. 8 in the welding position;

FIG. 13 is a section similar to FIG. 8 after an initial detachment;

FIG. 14 shows a section similar to FIG. 8 during the removal;

15 shows a section through a welding jaw.

A first exemplary embodiment of the device according to the invention shown in FIGS. 1 to 7 shows in detail a machine frame 10 with an essentially horizontal roller conveyor 12 arranged therein, which is composed of a plurality of rollers 14 arranged in one plane, which together form a feed plane 16 define for a board 18. In one In the central region of the roller conveyor 12, two pairs of rollers 20 and 22 and 24 and 26 are arranged at a distance from one another, the individual rollers 20 and 22 and 24 and 26 of each pair being arranged such that their axes of rotation are in a plane perpendicular to the feed plane 16 lie parallel to the feed plane and enclose it between them. The rollers 20 and 22 and 24 and 2β arranged in pairs lie in such a way that a plate 18 lying in the feed plane 16 can pass between the two rollers 20 and 22 and 24 and 26 and is acted upon by them in the direction of the feed plane 16, so that the circuit board 18 can be held by the rollers 20 and 22 and 24 and 26 arranged in pairs. For this purpose, the rollers 20 and 22 or 24 and 26 are preferably spring-loaded relative to one another. Each pair of rollers 20 and 22 and 24 and 26 is assigned a drive 28 or 30, each of which comprises a drive motor and corresponding gear means for driving the rollers 20 and 22 and 24 and 26 in opposite directions and also spring means for acting on the rollers in the direction of one another.

The rollers 20 and 22 as well as 24 and 26 arranged in pairs are driven in such a way that a board 18 inserted between them is moved in the feed direction, indicated by an arrow 32.

The board 18 inserted into the device described so far generally comprises a carrier 34, constructed from a central insulation body 36, which as a rule a metal liner 38, in particular a copper liner, bears on both surfaces. A photopolymer layer 40 with a protective film 42 covering it is laminated onto each of the metal claddings 33. Both the photopolymer layer 40 and the protective film 42 covering it generally do not extend to an outer edge of the carrier 34, but are at least set back with respect to its front edge.

The device described so far and also the platinum 18 in this form are known from the prior art. Details of the solution according to the invention are described below:

Between the rollers 20 and 22 as well as 24 and 26 arranged in pairs two detaching shoes serving as detaching guide elements 44 and 46 are provided which extend with their longitudinal axis across the roller conveyor 12 parallel to the rollers 14 and enclose the feed plane 16 between them. The release shoes 44 and 46 are expediently arranged with their longitudinal axes in a plane perpendicular to the feed plane 16, so that they lie vertically one above the other.

An actuator 48 or 50 is assigned to each of the detachment shoes 44 and enables the respective detachment shoe 44 to be displaced or in the plane perpendicular to the feed plane 16.

The detachable shoes 44 and 46 are expediently round on their side facing the feed plane 16 formed, in the simplest case, the release shoes 44 and 46 have a circular cylindrical shape. In the circumferential area of the detaching shoes 44 and 46 closest to the feed plane 16 there is in each case a welding jaw 52 and 54 which also extends over the entire length of the respective detaching shoe 44 and 46 and which according to the invention with its active front surface 56 or 58 is slightly above an upper surface of the respective release shoe 44 or 46 protrudes in the direction of the feed plane 16.

Furthermore, suction openings 64 are provided in the surface area 60 or 62 facing the feed plane 16, to which suction channels 66 extending into the interior of the detaching shoes 44 and 46 connect, which open into a suction channel 68 extending in the longitudinal direction of the detaching shoes 44 and 46, which is connected to a suction pump device, not shown in the drawing. With these suction openings 64, a peel-off film 70 can be held on the surface area 60 or 62 facing the feed plane 16.

To apply the peel-off film 70 to the surface area 60 or 62 facing the feed plane 16, an attachment rail 72 or 74 is assigned to each of the detaching shoes 44 or 46, which is provided over the surface area 60 or 62 of the respective detaching shoe 44 or 46 facing the feed plane 16. 46 is movable. Each contact rail 72 and 74 is assigned a swivel device 76 or 78 which is fixedly connected to the respective detaching shoe 44 or 46 and which guides the contact rail 72 or 74 on the surface 60 or 62 and between an extension Starting position, in which the contact rail 72 or 74 faces the rollers 24 or 26, can pivot into an end position, in which the contact rail 72 or 74 faces the rollers 20 or 22.

To detect a front edge 43 of the protective film 42, according to the invention, a sensor 80 or 82, which can be adjusted in the feed direction, is arranged between the roller 20 and the detachment shoe 44 and between the roller 22 and the detachment shoe 46, and the active surface 84 and 86 of the feeder 16 faces so that a board 18 moved along the feed plane 16 runs between the active surfaces 84 and 86 of the sensors 80 and 82, respectively. The sensors 80 and 82 are connected to a controller 88, which controls both the drive 28 of the rollers 20 and 22 and the actuators 48 and 50.

Finally, for winding up a peel-off film 70 wrapping around a detachment shoe 44 or 46, viewed in the feed direction 32, a take-up roll 90 and 92 is arranged behind the respective detachment shoe 44 and 46 and approximately above the roller 20 and 22, respectively Axis of rotation is also aligned parallel to the rollers 14. Each of the take-up reels 90, 92 is one

Drive 94 or 96 assigned.

The method according to the invention in connection with the execution according to the invention works as follows:

A board 18 is placed on the roller conveyor 12, which is then arranged in pairs in the feed direction 32 neten rollers fed and drawn between them. Characterized in that the rollers 20 and 22 are spring-loaded in the direction of the feed plane 16, the board 18 is firmly clamped between these rollers 20 and 22 and thus held. By driving the rollers 20 and 22 in opposite directions, the circuit board 18 is conveyed further in the feed direction 32, the front edges 43 of the protective films 42 held on both sides on the carrier 34 passing the active surfaces 84 and 86 of the sensors and thereby triggering a signal for the control 88. A distance between the respective sensor 80 and the welding jaw 52 and between the sensor 82 and the welding jaw 54 is already permanently stored in the control 88. The controller 88 thus allows the board 18 to be pushed forward in the feed direction 32 until the first front edge 43 of the protective film 42 lies exactly below the respective welding jaw 52 or 54. In this position, the drive 88 of the rollers 20 and 22 is stopped by the controller 88, so that the circuit board 18 stops.

Already from the previous peeling process, a remnant of the previously peeled protective film 42 is present on the surfaces 60 and 62 of the detaching shoes 44 and 46 facing the feed plane 16, which now represents the peeling film 70 and is held on the corresponding surface area 60 and 62 by the suction openings 64 becomes.

The corresponding release shoe 44 or 46, initiated by the control 88, is now loaded by the respective actuator 48 or 50 in the direction of the feed plane 16. moves so that the piece of the peel-off film 70 lying on the front surface 56 or 53 of the welding jaws 52 or 54 is pressed onto the front edge 43. According to the invention, the relative position of the front edge 43 is selected by the controller 83 such that the front edge 43 comes to lie approximately in the middle of the front surface 56 and 58 of the welding jaws 52 and 54, so that the welding jaws 52 and 54 become one when the pulse is heated the edge region of the protective film 42, which extends from the front edge 43 of the protective film 42 against the feed direction 32 to a rear edge of the respective front surface 56 or 53, is welded to the piece of the peel film 70 which extends over the same path. The central position of the front edge 43 is deliberately chosen so that even with a certain positioning tolerance it is ensured that the front edge 43 of the protective film 42 is always welded to the release film 70. The part of the peel-off film 70 which extends from the center of the front surface 56 or 53 of the welding jaws 52 or 54 in the feed direction 32 to a front edge of the front surface 56 or 53 cannot be welded, since there is no corresponding piece of protective film 42 opposite it.

This is consciously accepted, because for peeling off the protective film 42 strongly adhering to the photopolymer 40, it is extremely important that the peeling force acts directly on the front edge 43 in order to enable the protective film 42 to be easily removed from the photopolymer layer 40. Mach the welding of the peel-off film 70 to the protective film 42, the respective release shoe 44 or 46 is moved away from the feed plane 16 by means of the corresponding actuator 48 or 50, so that a tensile force on the front edge 43 of the protective film 42 with a perpendicular to the Feed plane 16 acts component, which leads to a detachment of the front edge 43 of the protective film 42 from the Fαtopolymer 40.

The method described above can thus be carried out with a different position of the front edges 43 on the different sides of the carrier 44, the drive 28 of the rollers 20 and 22 then having to be stopped and a pulling off in order to weld the respective front edge 43 to the associated release film 70 of the protective films 42 applied on both sides can only take place after the two leading edges 43 have been welded together. As a rule, however, it is possible to laminate the front polymer layer 40 with the protective film 42 on both sides of the carrier 34 such that the front edges 43 of the protective films 42 have the same distance from a front edge of the carrier 34. So that the respective distance between the sensors 80 and the welding jaw 52 or the sensor 82 and the welding jaw 54 can be the same size, so that, as shown in Fig. 3, the front edges 43 at the same time the drive 28 stops with the each peelable film can be welded. In addition, slight differences can be compensated for by adjusting the sensors 80 and 82 in the feed direction.

The subsequent simultaneous removal by moving the two release shoes 44 and 36 away from the feed plane 16 is shown in FIG. 4. As a result, the drive 28 is switched on again by the control 88, so that the board 18 is fed further in the feed direction 32 and at the same time the protective film 42 is removed in that the peel-off films 70 have the release shoes 44 and 46 on their rollers 24 and 26 respectively facing side are wound around the winding rollers 90 and 92, which wind up the pull-off film 70 and the protective film 42 welded to it by the drives 94 and 96. The drives 94 and 96 are expediently also controlled via the control 88.

When the board 18 is advanced further, the carrier 34 with the photopolymer layers 40 still laminated on both sides is inserted between the two rollers 24 and 26, which are likewise rotated in opposite directions by the drive 30 at the same speed as the rollers 20 and 22 and the carrier 34 with hold the laminated photopolymer layers 40. After the circuit board 18 has passed the rollers 20 and 22, the support with the laminated photopolymer layers is only held over the rollers 24 and 26.

The peeling process continues until a rear edge 41 passes the active surfaces 84 and 86 of the sensors 80 and 82, so that the sensors generate a further signal, after which the drives 94 and 96 of the take-up reel 90 and 92 are stopped. As a result, the removed protective film 42 is no longer wound up. At the same time, the swiveling devices 76 and 78 are set in motion, which move the two contact rails 72 and 74 from their starting position into their end position, as a result of which the remaining piece of protective film 42 to be removed is in each case on both sides of the carrier 34 to the surface areas 60 and 62 facing the feed plane 16 the release shoes 44 and 46 are put on and held by the suction openings 64. The suction device is expediently only switched on for as long as long as the piece of protective film 42 which has been removed has to be held on the surface regions 60 and 62. The peel-off film 70 has now become the peel-off film 70 for the next peel-off process.

Before the next pull-off operation begins, only the guide rails 72 and 74 have to be moved back from their end position into their starting position.

All conceivable sensors which are able to detect the front edge 43 and the rear edge 41 of the protective film 42 can be used for the exemplary embodiment described above. Optical sensors are preferably used for this purpose, since the photopolymer layer lying under the transparent protective film 42 is strongly colored by the previous exposure and thus has a clear contrast to the metal liner 38. However, electrical sensors can also be used, which on the one hand detect the conductivity on the metal lamination 38 and after passing the front edge 43 or the rear edge 41 determine the no longer existing conductivity on the protective film 42.

In a second exemplary embodiment of the device according to the invention, shown in FIGS. 8 to 14, parts identical to the first exemplary embodiment are provided with the same reference numerals, so that reference can be made to the statements relating to the first exemplary embodiment with regard to their description.

In contrast to the first embodiment, the detaching guide elements 44 and 46 are designed as detaching rollers, the outer cylinder jacket 100, 102 of which is rotatably mounted on a non-rotatable cylinder core 104, 106. The cylinder core 104, 106 is provided in a partial area facing the cylinder jacket 100, 102 with a cutout 108, 110 which forms the suction channel 68. The cutout 108, 110 is arranged in such a way that it adjoins an inner circumferential surface 112, 114 of the cylinder jacket 100 or 102 and is arranged on a side of the cylinder core 104, 106 facing the feed plane 16.

Just as in the first exemplary embodiment, the cylinder jacket 100, 102 is provided with suction openings 64 in a surface region 60 or 62 comprising a cylinder segment, to which the suction channels 66 penetrating the cylinder jacket 100 or 102 are connected. Through the suction openings 64 and the suction channels 66, the peel-off film 70 is then sucked in when the cylinder jacket 100 or 102 is rotated relative to the cylinder core 104 or 106 in such a way that the suction channels 66 open into the cutout 108 or 110 forming the suction channel . Each of the detaching rollers 44 and 46 can be moved by pneumatic actuators 48 and 50 in a plane perpendicular to the feed plane 16 towards or away from the feed plane 16. At the same time, the winding roller 90 or 92 is connected to the respective drive 94 or 96 via a clutch / brake device, not shown. The cylinder jacket 100 or 102 can thus be driven synchronously with the take-up roll 90 or 92.

In the second exemplary embodiment, the take-up rolls 90 and 92 are not driven directly by the respective drive 94 or 96, but the drive 94 or 96 comprises a drive roll 124 or 126, which with its outer circumference rests on the take-up roll 90 or 92 abuts and drives them on their outer circumference.

It is preferably provided in the second exemplary embodiment that the entire, jointly driven unit comprising the detaching roller 44 or 46, drive 94 or 96, drive roller 124 or 126 and take-up roller 90 or 92 as a whole in the direction of the feed plane 16 to or from this can be moved away. Furthermore, the axes of rotation of the detaching roller 44 or 46 of the drive roller 124 or 126 and of the take-up roller 90 or 92 lie in a plane 128 which runs transversely to the feed plane 16 and is preferably perpendicular thereto and are aligned parallel to one another and parallel to the feed plane 16 .

For guiding the peel-off film 70 and the protective film 42 which may be held on the peel-off roll 44 or 46 and the take-up roll 90 or 92 there is a guide shaft 134 or 136 extending from an outer surface area 130 or 132 of the cylinder shell 100 or 102 in the direction of the take-up reel 90 or 92, at the end opposite the cylinder shell 100 or 102 a pair of the release film 70 between holding conveyor rollers 138 and 140 is provided. These conveyor rollers 138 and 140 are rigidly coupled to the drive 94 and 96 for the take-up reel 90 and 92, the rotational speed of which is matched to the rotational speed of the drive rollers 124 and 126, in such a way that the pull-off film 70 is driven synchronously overall.

With these two pairs of conveyor rollers 138 and 140, the release film 70 is pushed back and forth in the guide shaft 134 and 136, respectively.

In addition, each guide shaft 134 or 136 is assigned a sensor 146 or 148 which determines whether or not peel-off film 70 is still guided in the guide shaft 134 or 136.

The guide shaft 134 or 136, with its shaft opening 150 or 152 facing the cylinder jacket 100 or 102, is designed in such a way that the peel-off film 70 guided therein can be applied directly to the outer jacket surface 130 or 132 of the cylinder jacket 100 or 102. The guide shaft 134 and 136 together with the sensors 146 and 148 and the conveyor rollers 138 and 140 as well as the drives 94, 96 with the drive rollers 124, 126 and the take-up rollers 90, 92 together with the detaching roller 44 and 46 are preferably also in Direction to the feed plane 16 to be moved. In addition, in the preferred exemplary embodiment shown, the guide shaft 134 or 136 is aligned parallel to the plane 128.

In the second exemplary embodiment, on both sides of the feed plane 16, behind the detaching roller 44 or 46, ie in the direction opposite to the feed direction 32, a blow pipe 154, 156 aligned parallel to the detaching roller 44 is provided, which coolant in the between the protective film 42 and the detaching roller 44th or 46 remaining space in order to cool the weld between the peel-off film 70 and the protective film 42 after the welding process. The blow pipe 154, 156 can also be arranged in front of the detaching roller 44, 46.

Furthermore, a cooling pipe 158 or 160 can advantageously be provided on the side of the detaching roller 44 or 46 facing away from the feed plane 16, in front of which the welding jaws 52 or 54 can be positioned by rotating the respective cylinder jacket 100 or 102 in order to rotate the welding jaws 52 or 54 cooling to a certain, selectable temperature.

The second exemplary embodiment of the device according to the invention now works as follows, as shown in FIGS. 9 to 14:

In the starting position, the detaching roller 44 or 46 is so far away from the feed plane by means of the pneumatic actuator 48 or 50 that the board 18 can be inserted. In addition, the peel-off film 70 is located in the guide shaft 134 or 136 with its edge 162 directly in an end position held by the sensor 146 or 148. This is achieved by winding the release film 70 onto the take-up roll 90 or 92 until the edge 162 has passed the sensor 146 or 148. At this point, the drive 94 or 96 is switched off by the control 88. Furthermore, the cylinder jacket 100 or 102 is rotated by the drive 94 or 96 during the winding of the peel-off film 70 onto the winding roller 90 or 92 to such an extent that the welding jaws 52 or 54, which is embedded in the cylinder jacket 100 or 102, respectively , the cooling pipe 158 or 160 faces. This position is at the same time the release film application position of the cylinder jacket 100 or 102.

Since, just as in the first exemplary embodiment, the suction jaws 66 and 54 are provided on both sides of the welding jaws 52 and 54, the suction channels 66 are arranged approximately opposite the shaft opening 150 and 152 or in the direction of the feed plane 16 with the clearance 108 forming the suction channel 68 or 110 in connection, so that 66 air can be sucked in through these suction channels.

Now that the board 18 has been advanced so far that it is detected by the sensors 80 and 82, the controller 88 switches on the drive 94 and 96 in the unwinding direction, whereby the winding roll 90 and 92 as well as the conveyor rollers 138 and 140 sets in motion and advances the peel-off film 70 via the point detected by the sensor 146 or 148 with its edge 162 in the direction of the feed plane until it comes to rest on the outer lateral surface 130 or 132 of the cylinder jacket 100 or 102 and is held on the cylinder jacket 100 or 102 by the suction openings 64 of the suction channels 66 connected to the suction channel 68. The distance by which the peel-off film 70 has to be displaced for this purpose is known from the geometrical structure, so that this is determined by detecting the revolutions of the conveyor rollers 138 of an angle encoder is precisely adjustable. This position is shown in Figure 10.

At the same time, the welding jaws 52 and 54 are heated by pulse heating while the pull-off film 70 is being advanced.

Subsequently, the cylinder jacket 100 or 102 is rotated by switching on the clutch / brake unit so far that the welding jaws 52 and 54 come into their welding position, in which they face the feed plane 16, the winding rollers being driven by the drive 94 and 96, respectively 90 or 92 and the conveyor rollers 138 and 140 must also turn in the unwinding direction.

During this turning back of the cylinder jacket 100 or 102, an increasing number of suction channels 66 comes into connection with the suction channel 68, so that their suction openings 64 additionally hold the peel-off film 70.

Furthermore, during this turning of the cylinder jacket 100 or 102 into the welding position, the plate 18 is simultaneously advanced so far that the front edge 43 of the protective film 42 is opposite the welding jaws 52 and 54 in the welding position (FIG. 11).

In this position, the pulse heating for the welding jaws 52 and 54 is also switched off.

By moving the detaching roller 44 in the direction of the circuit board 18, the peel-off film 70 is then welded to the protective film 42 in the area of the front edge 43 with its area resting on the welding jaws 52 and 54, just as in the first exemplary embodiment. This is shown in Figure 12.

After welding, the entire device remains until the blow pipes 154 and 156 have blown coolant into the space between the detaching roller 44 and 46 and the circuit board 18 for a sufficiently long time, around the weld seam between the peel-off film 70 and the protective film 42 to cool.

Subsequently, the drive 94 or 96 is switched on, the cylinder jacket 100 or 102, the conveyor rollers 138 or 140 and the winding roller 90 or 92 being driven at the same time, and at the same time the board 18 is also moved further in the feed direction 32 with a corresponding feed. As a result, the protective film 42 is lifted and detached from the photopolymer layer 40 by the peel-off film 70, the peeled-off protective film 42 wrapping lengthwise around the outer circumferential surface 130 or 132 before it enters the guide shaft 134 or 136 through the shaft opening 150 or 152 .

As soon as the cylinder jacket 100 or 102 is rotated so far that the welding jaws 52 or 54 are in their pull-off film application position, in which they are positioned opposite the cooling tube 158 or 160, the drive of the cylinder jacket 100 or 102 switched off. During this time, the weld seam between the protective film 42 and the peel film 70 has cooled down to such an extent that it has sufficient stability (FIG. 13)

Thus, as shown in FIG. 14, by moving the detaching roller 44 or 46 away from the feed plane 16 and thus from the plate 18, the part which has already been pulled off can be removed form an angle between the protective film 42 and the protective film 42 still adhering to the photopolymer layer 40 and is also deflected into the guide shaft 134 or 136 by the detaching roller 44 or 46, which remains rotationally fixed. In this actual pull-off position, shown in FIG. 14, the circuit board 18 is pushed forward until the protective film 42 has been pulled off completely. During this entire peeling process, the sensor 146 or 148 continuously monitors whether the peeled protective film 42 runs through the guide shaft 134 or 136 in order to determine and report to the controller 88 whether the weld seam between the peeling film 70 and the protective film 42 has broken, if necessary . As soon as the protective film 42 has been removed completely, it forms the new release film 70 and the drive 94 or 96 remains switched on until its edge 162 has passed the sensor 146 or 148. In this case, the drive is switched off and the entire device is again in the starting position, as shown in FIG. 9.

A preferred exemplary embodiment of a welding jaw 52 or 54 according to the invention, shown in FIG. 15, comprises a heating wire 170, which is insulated from the cylinder jacket 100 or 102 by a layer 172 of insulating material, in particular PTFE, and also externally by a layer 174 of insulation material, also in particular PTFE, is covered. This ensures that the release film 70 does not stick to the heating wire 170, which preferably has a rectangular cross section, and, moreover, is not locally overheated too much.

In other embodiments of the device according to the invention and of the method according to the invention, another guidance of the peel-off film 70 is also conceivable. This can be passed between the roller 20 and the detachment shoe 44 or the roller 22 and the detachment shoe 46, so that the release film 70 does not have to be looped around the detachment shoe 44 or 46 during the actual detaching process. Plierzu but the drives 94 and 96 for the take-up reel 90 and 92 may have to be provided with a separate control, since these now only control the detachment process. The advantage of this method can be seen in the fact that the protective film 42 is strongly bent backwards, i.e. counter to the feed direction 32, when detaching and thus has a small radius of curvature in the detaching area, which facilitates detaching from the photopolymer layer. After the pulling-off process has ended, the last piece of protective film 42 which has been pulled off would also have to be placed against surface areas 60 and 62 facing feed plane 16, so that welding with front edge 43 of subsequent protective film 42 is possible again for the next process.

Claims

Patent claims

1. Method for peeling off a protective film from a carrier, in particular from a printed circuit board with a laminated photopolymer layer. by means of a peelable film which can be connected to the protective film and which is placed on the protective film and with which the protective film is peeled off by means of a movement relative to the carrier, so that the protective film is welded to the peelable film with a partial area.

2. The method according to claim 1, characterized in that the peel-off film and the underlying protective film be pressed against the carrier during welding.

3. The method according to claim 1 or 2, characterized in that the partial region is formed by part of an edge region of the protective film.

4. The method according to claim 3, characterized in that the edge region is formed by the outer edge of the protective film extending along a side edge.

5. The method according to claim 4, characterized in that the protective film is welded along its side edge at least in sections to the release film.

6. The method according to claim. 5, characterized in that the protective film is welded along the side edge with the peeling film.

7. The method according to any one of the preceding claims, characterized in that the protective film is welded to the peel-off film in the region of a corner.

8. The method according to any one of the preceding claims, characterized in that a film made of material with a similar melting point as the protective film is used as a release film.

9. The method according to claim 8, characterized in that a film made of the same material as the protective film is used as the release film.

10. The method according to any one of the preceding claims, characterized in that a film with a thickness comparable to that of the protective film is used as the release film.

11. The method according to any one of the preceding claims, characterized in that the removed protective film is wound up with the release film.

12. The method according to any one of the preceding claims, characterized in that the removed protective film encloses an angle of <160 ° with the protective film adhering to the support.

13. The method according to claim 12, characterized in that the removed protective film with the protective film still adhering to the carrier encloses an angle of <90 °.

14. The method according to claim 13, characterized in that the removed protective film with the protective film still adhering to the carrier includes an acute angle <20 °.

15. The method according to any one of the preceding claims, characterized in that the protective film adhering to the carrier is removed tangentially along a curved path.

16. The method according to claim 15, characterized in that the protective film adhering to the carrier is peeled off tangentially along the curved path at the beginning of the peeling process and then at an angle to the carrier.

17. The method according to any one of the preceding claims, characterized in that a protective film originating from a previous peeling process is used as the peel-off film.

18. The method according to any one of the preceding claims, characterized in that the protective films are removed simultaneously on both sides of the carrier.

19. Device for peeling off a protective film from a carrier, in particular for carrying out the method according to one of claims 1 to 18, with a holder for the carrier and a device for placing a peelable film that can be connected to the protective film on the protective film and for removing the peelable film the protective film from the carrier by a series movement between the carrier and the protective film, characterized in that a welding device (52, 54) is provided, which attaches the peeling film (70) to the protective film (42) and welds it together.

20. The apparatus according to claim 19, characterized in that the welding device (52, 54) and the carrier (34) can be advanced towards each other.

21. The apparatus according to claim 19 or 20, characterized in that by the welding device (52, 54) in a welding position, the release film (70) against the protective film (42) and the latter (42) against the carrier (34) with an adjustable force are pressable.

22. Device according to one of claims 19 to 21, characterized in that a welding temperature of the welding device (52, 54) is adjustable.

23. Device according to one of claims 19 to 22, characterized in that a welding time is adjustable.

24. Device according to one of claims 19 to 23, characterized in that the welding device is designed as a welding jaw.

25. Device according to one of claims 19 to 24, characterized in that a removal device (90, 92, 94, 96) for the peel-off film (70 and the protective film (42) welded to it is provided.

26. The device according to claim 25, characterized in that the removal device comprises a winding device (90, 92, 94, 96) for the peel-off film (70) with a welded-on protective film (42).

27. Execution according to one of claims 19 to 26, characterized in that the Halterun-j is a transport device (rollers 20, 22, 24, 26) for a feed path (12) on which the carrier (34) can be transported.

28. Device according to one of claims 19 to 27, characterized in that a positioning device (80, 82, 83) is provided, through which for welding the protective film (42) to the release film (70) of the carrier (34) and the welding device (52, 54) can be brought into a predeterminable welding position relative to one another.

29. The device according to claim 28, characterized in that the positioning device (38) comprises sensors (30, 32; for detecting the protective film (42).

30. Performance according to claim 29, characterized in that the sensors (30, 82) respond to side edges (41, 43) of the protective film (42).

31. Execution according to one of claims 28 to 30, characterized in that the positioning device comprises a device (88) for interrupting a feed movement of the transport device (rollers 20, 22, 24, 26).

32. Execution according to one of claims 2 & to 31, characterized in that in the welding position a welding-active surface of the welding device (52, 54) both overlaps an edge region of the protective film (42) to be welded with the release film (70) and also over this edge region the protective film (42) protrudes outwards.

33. Apparatus according to claim 32, characterized in that in the welding position, the side edge (41, 43) of the protective film (42) lies in a central region of the active welding surface of the welding device (52, 54).

34. Device according to one of claims 19 to 33, characterized in that the welding device (52, 54) extends over the entire width of the feed path (12).

35. Device according to one of claims 19 to 34, characterized in that devices (64, 65) for holding one with the protective film (42) welding part of the release film (70) are provided.

36. Apparatus according to claim 35, characterized in that the devices (64, 66) for holding the peel-off film (70) are arranged on the side of the welding device (52, 54).

37. Apparatus according to claim 35 or 36, characterized in that the means for holding the release film are suction openings (64).

38. Device according to one of claims 35 to 37, characterized in that a device (72, 74,

76, 78; 134, 138, 136, 140) for applying the peel-off film (70) to the devices (64, 66) for holding the peel-off film (70).

39. Device according to one of claims 19 to 38, characterized in that a detaching guide element (44, 46) is provided, around which the peel-off film (70) is guided.

40. Apparatus according to claim 39, characterized in that the detaching guide element (44, 46) and the carrier

(34) are deliverable to each other.

41. Apparatus according to claim 38 or 39, characterized in that the welding device (52, 54) is integrated in the detaching guide element (44, 46) on its side facing the carrier (34).

42. Device according to one of claims 39 to 41, characterized in that the detaching guide element (44, 46) extends across the feed path (12).

43. Device according to one of claims 39 to 42, characterized in that the detaching guide element

(44, 46) is rotatable.

44. Apparatus according to claim 43, characterized in that the release guide element (44, 46) is rotatable between a welding position and a peel-off film application position.

45. Device according to one of claims 35 to 44, characterized in that the detaching guide element

(44, 46) is provided with the devices (64, 66) for holding a part of the release film (70) to be welded to the protective film (42) thereon.

46. Apparatus according to claim 45, characterized in that the means (64, 66) for holding the peel-off film (70) on a side (60, 62) of the detaching guide element (44, 46) which is facing the carrier (34) are arranged.

47. Device according to one of claims 38 to 46, characterized in that the device for applying the peel-off film (70) to the devices (64, 66) for holding the peel-off film (70) one to the detaching guide element

(44, 46) leading peel-off film guide (134, 138, 136, 140).

48. Apparatus according to claim 47, characterized in that the peel-off film guide (134, 138, 136, 140) has a sensor (146, 148) for detecting the peel-off film (70).

49. Device according to one of claims 19 to 48, characterized in that the peeling film (70) is the peeled protective film (42) from a previous peeling process.

50. Device according to one of claims 19 to 49, characterized in that a weld seam cooling device (154, 156) is provided.