Field of application of the invention

The present invention is applied to the technical field of processing thin metal sheets in order to obtain electronic components or the like.

Namely, the present invention relates to an apparatus for reciprocally overlapping two metal sheets (e.g. copper) by interposing a double sided adhesive film therebetween so as to obtain a composite panel having a so-called "sandwich" structure (the core of which consisting of the double sided adhesive film and the "shells" of which consisting of the metal sheets).

Overview of the prior art

As is known, today's need for compactness ensures that electronics are increasingly evolving towards the miniaturization of the integrated circuits. In particular, the metal sheets, especially made of copper, to be processed for manu- facturing the aforesaid circuits and other similar electronic components, are increasingly thinner.

However, the thinner a metal sheet is, the less is the bending and torsional rigidity thereof. The poor rigidity makes certain mechanical processing to be performed on the sheet highly difficult, if not otherwise impossible. Accordingly, the thinner a metal sheet is, the more difficult it is to perform mechanical processing thereon.

To obviate this drawback, the metal sheets are laid on highly rigid supports be- fore being subjected to any mechanical processing. Once the mechanical processing is complete, each sheet should however be removed from the respective support and this operation is anything but easy. Mechanical processing indeed further compromises the rigidity of the sheet and therefore the risks are higher of damaging the sheets when they are removed from their respective supports.

Objects of the invention

It is the object of the present invention to overcome the aforesaid drawbacks by indicating an apparatus by means of which two metal sheets are adhered to two respective faces of a suitable double sided thermolabile adhesive film, such as CF 658™ from Feng Ting Co. or "Revalpha™" films from Nitto Denko. The double sided adhesive films of the aforesaid type are extremely thin (they have a thickness generally from 50 microns to 500 microns) and dissolve once a limit temperature is exceeded, generally from 90°C to 170°C.

A composite panel comprising a double sided adhesive film interposed between two thin metal sheets indeed has a much higher rigidity than that of each of the two sheets acting as shells of the panel. This ensures that each metal sheet may be mechanically processed by using the other sheet of the panel as a support. Once the mechanical processing of both sheets is complete, the latter can be easily separated from each other by heating the composite panel past the aforesaid limit temperature. This overcomes the drawbacks set forth above. It is thus the object of the present invention to indicate an apparatus which allows to manufacture the above composite panel from two thin metal sheets and from a double sided thermolabile adhesive film of the aforesaid type. For con- venience of disclosure, in the continuation of the present description the term "double sided adhesive film" indicates any double sided thermolabile adhesive film of the aforesaid type.

Summary of the invention

The present invention relates to an apparatus for manufacturing a composite panel comprising a first and a second metal sheet opposite to each other and adhering to a double sided adhesive film interposed therebetween, the apparatus comprising a first and a second lamination stage, the first lamination stage including:

• first support means suitable for supporting the first sheet;

• a first and a second cylinder opposite to each other and rotatable about a respective longitudinal axis, said first cylinder being suitable for allowing an at least partial winding of the double sided adhesive film thereon;

• first translation means suitable for causing the first support means to translate between the first and second cylinders;

• second translation means suitable for causing the first and second cylinders to translate with respect to each other, said second translation means being suitable for bringing the first and second cylinders at a reciprocal distance such as to press the double sided adhesive film against the first sheet when the latter passes between the two cylinders, so as to allow to obtain a semifinished panel comprising the first sheet and the double sided adhesive film adhering to each other,

the second lamination stage including:

• second support means suitable for supporting the semi-finished panel;

• overlapping means suitable for overlapping the second sheet on the semifinished panel at the double sided adhesive film;

• alignment means suitable for aligning the second sheet and the semi-finished panel with each other;

• a third and a fourth cylinder opposite to each other and rotatable about a respective longitudinal axis;

• third translation means suitable for causing the second support means to translate between the third and fourth cylinders;

· fourth translation means suitable for causing the third and fourth cylinders to translate with respect to each other, said fourth translation means being suitable for bringing the third and fourth cylinders at a reciprocal distance such as to press the second sheet, which is aligned with the semi-finished panel, against the double sided adhesive film when the semi-finished panel and the second sheet pass between the third and fourth cylinders, so as to allow to obtain the composite panel.

The first lamination stage of the apparatus of the invention serves to lay out (and accordingly cause to adhere) the double sided adhesive film on one of the two metal sheets so as to obtain a semi-finished panel comprising two of the three layers of the composite panel which is to be manufactured with the apparatus of the invention. The second lamination stage serves to lay out the other metal sheet on the semi-finished panel at the free face of the double sided adhesive film.

Further innovative features of the present invention are described in the dependent claims.

According to one aspect of the invention, the first lamination stage further com- prises:

• means suitable for removing a first protective layer adhering to the double sided adhesive film at a first face thereof,

> the first cylinder being suitable for allowing an at least partial winding of the double sided adhesive film, without the first protective layer, at a second pro- tective layer adhering to a second face of the film, opposite to said first face,

> the second translation means being suitable for bringing the first and second cylinders at a reciprocal distance such as to press the double sided adhesive film, at the first face, against the first sheet when the latter passes between the two cylinders,

> the second support means being suitable for supporting the semi-finished panel with the second face of the double sided adhesive film, without the second protective layer, facing the second sheet,

> the fourth translation means being suitable for bringing the third and fourth cylinders at a reciprocal distance such as to press the second sheet, which is aligned with the semi-finished panel, against the second face of the double sided adhesive film when the semi-finished panel and the second sheet pass between the two cylinders.

In the first lamination stage, the first metal sheet is laid on the first support means and is caused to translate between the first and second cylinders. Once the first protective layer has been removed, the double sided adhesive film is partially wound onto the first cylinder at the second protective layer (so as not to adhere to the first cylinder) and is pressed, at the first face (adhesive), against the first metal sheet so as to adhere to the latter. The feeding of the first metal sheet and of the double sided adhesive film between the first and second cylinders results in the formation of the semi-finished panel.

In the second lamination stage, once the second protective layer has been re- moved, the semi-finished panel is laid on the second support means so that the second face of the double sided adhesive film faces upwards. The second metal sheet is overlapped on the semi-finished panel at the aforesaid second face and is aligned with the latter. The second metal sheet is then pressed against and caused to adhere to the second face of the double sided adhesive film. The feeding of the semi-finished panel and of the second metal sheet between the third and fourth cylinders results in the formation of the composite panel.

Brief description of the drawings

Further objects and advantages of the present invention will become apparent from the detailed description provided below of an embodiment thereof and from the accompanying drawings merely given by way of a non-limiting example, in which:

- figure 1 shows a diagrammatic side view of a first lamination stage of an apparatus according to the present invention;

- figure 2 shows a diagrammatic side view of a second lamination stage of the apparatus in figure 1 , prepared for obtaining a composite panel;

- figure 3 shows a diagrammatic side view of the second lamination stage in figure 2, during the realization of the composite panel.

Detailed description of some preferred embodiments of the invention

For convenience of disclosure, in the present description reference is made only to a preferred exemplary embodiment in which the apparatus is used to manufacture a composite panel comprising two copper sheets opposite to each other and adhering to a CF 658™ or Revalpha™ film interposed therebetween. It is to be apparent that the apparatus described is not limited to the aforesaid embodiment, but may be used to manufacture any composite panel comprising two metal sheets opposite to each other and adhering to a double sided adhesive film interposed therebetween.

In the continuation of the present description, a figure may also be shown with reference to elements not expressly indicated in that figure but in other figures. The scale and proportions of the different elements depicted do not necessarily correspond to the actual ones.

Figure 1 shows a first lamination stage 1 of an apparatus of the invention for manufacturing a composite panel 28 (shown in figure 3) comprising a first and a second metal sheet 2, 3 (the latter is shown in figures 2 and 3) opposite to each other and adhering to a double sided adhesive film 4 interposed therebetween. The sheets 2 and 3 are preferably made of copper and preferably have a thickness from 10 microns to 100 microns. Film 4 is preferably a CF 658™ or Reval- pha™film.

The lamination stage 1 comprises a first and a second cylinder 5 and 6 having parallel axes, which are opposite to each other and are rotatable about the respective longitudinal axis, which is preferably arranged horizontally. The cylinders 5 and 6 are preferably arranged one above the other with the longitudinal axes parallel to each other and lying in a preferably vertical plane. Cylinder 6 (the lower one in figure 1) is preferably made of steel and preferably has a diameter from 50 mm to 70 mm, and even more preferably of 60 mm. Cylinder 5 is preferably made of steel and covered in silicone, preferably with a hardness of 45SH, and has a larger diameter than that of cylinder 6, preferably from 55 mm to 75 mm, even more preferably of 66 mm.

The lamination stage 1 further comprises a belt 7 sliding between the cylinders 5 and 6, supported by a pair of rollers 8 and 9, preferably idler, lying on opposite sides with respect to cylinder 6. Namely, belt 7 extends preferably horizontal from roller 8 (on the left in figure 1 ) to roller 9 (on the right in figure 1 ), thus touching cylinder 6 almost tangentially to the latter. Belt 7 has a width (measured orthogonally to the plane of the sheet in figure 1) which is preferably wider than the width of film 4. In particular, belt 7 has a width such as to reversibly cover the upper portion of cylinder 6, i.e. the portion at which belt 7 is in contact with cylinder 6. Belt 7 is preferably polymeric, and even more preferably made of PET. It has a thickness preferably from 10 microns to 100 microns, and even more preferably of 50 microns.

The cylinders 5 and 6 are motorized. Namely, the lamination stage 1 comprises a motor and a motion transmission system (not shown in the figures) by means of which the cylinders 5 and 6 are rotatable in opposite directions. The rolling friction between cylinder 6 and belt 7 is sufficient to result in a rotation of cylinder 6 causing belt 7 to slide integrally therewith. The means which cause the cylinders 5 and 6 to rotate thus act as first translation means of belt 7 between the cylinders 5 and 6.

The lamination stage 1 comprises another belt 10 sliding between the cylinders 5 and 6, supported by another pair of rollers 11 (only one of which is shown in the figure), preferably idler. Namely, belt 10 surrounds cylinder 5 almost at the middle thereof facing roller 8, to then extend, preferably horizontally, to roller 11 (lying on the same part of roller 9 with respect to the cylinders 5 and 6). Similarly to what is said for belt 7, belt 10 has a width which is preferably wider than the width of film 4. In particular, belt 10 has a width such as to reversibly cover the side portion (on the left in figure 1 ) of cylinder 5, i.e. the portion at which belt 10 is in contact with cylinder 5. The rolling friction between the latter and belt 10 is sufficient to result in a rotation of cylinder 5 causing belt 10 to slide integrally therewith. The means which cause the cylinders 5 and 6 to rotate thus also act as first translation means of belt 10 between the cylinders 5 and 6. Similarly to belt 7, belt 10 preferably is polymeric, and even more preferably is made of PET, and it has a thickness preferably from 10 microns to 100 microns, and even more preferably of 50 microns.

As shown in figure 1 , the copper sheet 2 may be laid on belt 7. The latter therefore acts as support means of sheet 2. When sheet 2 is laid on belt 7, a sliding of belt 7 causes sheet 2 to be transported between the cylinders 5 and 6.

The double sided adhesive film 4 is covered at both faces by two protective layers (non adhesive) 12 and 13 which adhere thereto. Due to the presence of the layers 12 and 13, film 4 may be rolled on itself to form a roll 14. The latter is partially unrolled so that film 4 is partially wound about cylinder 5, preferably at the portion thereof where belt 10 is wound. The latter is thus interposed between film 4 and cylinder 5. Film 4 is wound onto cylinder 5 at the protective layer 13. The latter prevents film 4 from being glued to belt 10. The rolling friction between the latter and the protective layer 13 is sufficient to result in a rotation of cylinder 5 causing film 4 to slide integrally therewith. A rotation of cylinder 5 thus causes roll 14 to be unrolled.

The lamination stage 1 comprises a roller 15, preferably idler, touched preferably tangentially by the double sided adhesive film 4 at the stretch of the latter which extends from roll 14 to cylinder 5. In particular, roller 15 is in contact with film 4 at the protective layer 12. The force of adhesion between film 4 and roller 5 is greater than the force of adhesion between layer 12 and film 4. This ensures that a sliding of film 4 on cylinder 5 causes the removal of the protective layer 12 which is collected by a known winding device (and therefore not shown) arranged downstream of roller 15. The stretch of film 4 wound on cylinder 5 thus does not have the protective layer 12.

In addition to being motorized, the cylinders 5 and 6 may be shifted with respect to each other. Namely, the lamination stage 1 comprises an actuator (not shown in the figures) by means of which the reciprocal distance of the cylinders 5 and 6 may be adjusted. The latter may be moved close to each other so that film 4 (partially wound on cylinder 5) may be pressed against the copper sheet 2 when the latter passes between the cylinders 5 and 6. Since film 4 is wound onto cylinder 5 at the protective layer 13, film 4 may be pressed by cylinder 5 against sheet 2 at the face of film 4 which has no protective layer 12. This ensures that when the aforesaid compression takes place, film 4 adheres to sheet 2 thus forming a semi-finished panel 16 comprising sheet 2 and film 4 (in conjunction with the protective layer 13) adhering to each other.

The first lamination stage 11 comprises means for removing the protective layer 13 from film 4 before the passage of the semi-finished panel 16 at a second lamination stage 20 of the apparatus of the invention. Said removal means are of known type. Therefore, further details will not be provided. Alternatively, the removal operation of the protective layer 13 from film 4 may be performed manually.

Figures 2 and 3 show the second lamination stage 20, successive to the lami- nation stage 1. The lamination stage 20 comprises a third and a fourth cylinder 21 and 22 having parallel axes, which are opposite to each other and are rotat- able about the respective longitudinal axis, which is preferably arranged hori- zontally. Similarly to the cylinders 5 and 6, the cylinders 21 and 22 are preferably arranged one above the other with the longitudinal axes parallel to each other and lying in a preferably vertical plane. The cylinders 21 and 22 are preferably made of steel and covered in silicone, preferably with a hardness of 60SH, and preferably have the same diameter. The latter is preferably from 40 mm to 100 mm, and even more preferably is 60 mm.

The lamination stage 20 further comprises a belt 23 sliding between the cylinders 21 and 22, supported by a pair of rollers, preferably idler (not shown in the figures). Namely, belt 23 surrounds cylinder 22 (the lower one in figures 2 and 3) almost at the quadrant thereof facing cylinder 21 and towards the left in figures 2 and 3 (i.e. at the "north-west" quadrant) to then extend, preferably horizontally, to the right. Belt 23 has a width which is preferably wider than the width of film 4. In particular, belt 23 has a width such as to reversibly cover the aforesaid quadrant of cylinder 22, i.e. the portion of the latter at which belt 23 is in contact with cylinder 22. Belt 23 is preferably polymeric, and even more preferably made of PET. It has a thickness preferably from 10 microns to 100 microns, and even more preferably of 50 microns.

Similarly to the cylinders 5 and 6, the cylinders 21 and 22 are motorized. Namely, the lamination stage 20 also comprises a motor and a motion transmission system (not shown in the figures) by means of which the cylinders 21 and 22 are rotatable in opposite directions. The rolling friction between cylinder 22 and belt 23 is sufficient to result in a rotation of cylinder 22 causing belt 23 to slide integrally therewith. The means which cause the cylinders 21 and 22 to rotate thus act as second translation means of belt 23 between the cylinders 21 and 22.

The lamination stage 20 comprises another belt 24 sliding between the cylinders 21 and 22, supported by another pair of rollers, preferably idler (not shown in the figures). Namely, belt 24 surrounds cylinder 21 almost at the quadrant thereof facing cylinder 22 and towards the left in figures 2 and 3 (i.e. at the "south-west" quadrant) to then extend, preferably horizontally, to the right. Similarly to what is said for belt 23, belt 24 has a width which is preferably wider than the width of film 4. In particular, belt 24 has a width such as to reversibly cover the aforesaid quadrant of cylinder 21 , i.e. the portion of the latter at which belt 24 is in contact with cylinder 21. The rolling friction between the latter and belt 24 is sufficient to result in a rotation of cylinder 21 causing belt 24 to slide integrally therewith. The means which cause the cylinders 5 and 6 to rotate thus also act as second translation means of belt 24 between the cylinders 21 and

22. Similarly to belt 23, belt 24 preferably is polymeric, and even more preferably is made of PET, and it has a thickness preferably from 10 microns to 100 microns, and even more preferably of 50 microns.

As shown in figures 2 and 3, the semi-finished panel 16 may be laid on belt 23. In particular, once the protective layer 13 has been removed from the double sided adhesive film 4, panel 16 may be laid on belt 23 at the copper sheet 2, i.e. with film 4 facing upwards in figures 2 and 3. Otherwise, panel 16 would be glued to belt 23. The latter therefore acts as support means of panel 16. When panel 16 is laid on belt 23, a sliding of belt 23 causes panel 16 to be transported between the cylinders 21 and 22.

The lamination stage 20 comprises a chute 25 tilted towards belt 23 and on which the copper sheet 3 may be laid. Chute 25 preferably lies on the opposite part of the horizontal stretches of the belts 23 and 24 with respect to the cylinders 21 and 22. The inclination of chute 25 is preferably from 20° to 40°, and even more preferably is 30°. Due to its own weight, when it is laid on chute 25, sheet 3 tends to slide towards belt 23, preferably in an intermediate position between the cylinders 21 and 22. When the semi-finished panel 16 is laid on belt

23, chute 25 allows an overlap of sheet 3 on panel 16 at the double sided adhesive film 4.

The lamination stage 20 further comprises a stop 26 which can be shifted by means of a linear actuator 27 (e.g. a pneumatic cylinder) between a first position (shown in figure 2) in which stop 26 is at least partially interposed between the cylinders 21 and 22 almost in contact with belt 23, and a second position (shown in figure 3) in which stop 26 is at a given distance from belt 23. Namely, when stop 26 is in the first position, it acts as stop means of the semi-finished panel 16 and of the copper sheet 3. When stop 26 is in the first position, it thus allows panel 16 and sheet 3 to be aligned with each other. When stop 26 is in the second position, it does not oppose a translation of panel 16 between the cylinders 21 and 22.

In addition to being motorized, the cylinders 21 and 22 may be shifted with respect to each other. Namely, the lamination stage 20 comprises an actuator (not shown in the figures) by means of which the reciprocal distance of the cylinders 21 and 22 may be adjusted. The latter may be moved close to each other so that sheet 3 may be pressed against panel 16 (at film 4) when the latter passes between the cylinders 21 and 22. Since film 4 (without the protective layer 12) faces cylinder 21 , the aforesaid compression ensures that film 4 ad- heres to sheet 3, thus forming the composite panel 28 comprising the sheets 2 and 3 opposite to each other and adhering to the double sided adhesive film 4 interposed therebetween.

Incidentally, when stop 26 is in the second position, it is sufficiently far from belt 23 so as to allow a translation of both panel 16 and sheet 3 overlapping the lat- ter between the cylinders 21 and 22.

It is now worth noting that the operation of the apparatus of the invention as a whole will be shown below in order to obtain panel 28 from the sheets 2 and 3 and from the roll 14 of film 4.

Sheet 2 is laid on belt 7 (of the lamination stage 1 ) at the stretch thereof be- tween roller 8 and cylinder 6. Roll 14 is partially unrolled so as to wind film 4 onto cylinder 5 without removing the protective layer 12 through the contact with roller 15. The cylinders 5 and 6 are therefore moved close to each other so as to cause film 4 to adhere to belt 7. The cylinders 5 and 6 are then placed in rotation so as to cause sheet 2 to slide towards them. When sheet 2 passes be- tween the rollers 5 and 6, the latter is inserted between belt 7 and film 4, thus adhering thereto and forming the semi-finished panel 6.

Once the formation of the semi-finished panel 16 is complete, the belts 7 and 10 are moved away from panel 16 by means of the rollers 9 and 11 and any excess portions of film 4 with respect to sheet 2 are removed manually or auto- matically by means of known cutting systems.

The belts 7 and 10 are "expendable" and perform a protective function towards the cylinders 5 and 6. In particular, they prevent the latter from coming in con- tact with the glue of film 4. Following the pressure of the latter against sheet 2, the glue of film 4 indeed tends to overflow from the semi-finished panel 16 during the formation thereof. The belts 7 and 10 prevent the deposit of glue onto the cylinders 5 and 6.

Panel 16 is then laid on belt 23 (of the lamination stage 20) below chute 25. Stop 26 is arranged in the first position and panel 16 is abutted against stop 26. Sheet 3 is laid on chute 25 and is also arranged so as to abut against stop 26. In this configuration (shown in figure 2), panel 16 and sheet 3 are vertically aligned (possibly also horizontally by means of a shoulder with which chute 25 is equipped, not shown in the figures). The cylinders 21 and 22 are therefore moved close to each other so as to cause sheet 3 to adhere to panel 16, which does not have the protective layer 13. Stop 26 is then moved away and the cylinders 21 and 22 are placed in rotation so as to cause sheet 3 and panel 16 to slide therebetween (as shown in figure 3). Therefore, the film 4 of panel 16 ad- heres to sheet 3, thus forming the composite panel 28.

Once the formation of the composite panel 28 is complete, the belts 23 and 24 are moved away from panel 28 by means of rollers (not shown in the figures) and any excess portions of film 4 with respect to sheet 3 are removed manually or automatically by means of known cutting systems.

Similarly to the belts 7 and 10, the belts 23 and 24 are "expendable" and perform a protective function towards the cylinders 21 and 22, thus also preventing the latter from coming in contact with the glue of film 4. Following the pressure of panel 16 against sheet 3, the glue of film 4 indeed tends to overflow from the composite panel 28 during the formation thereof. The belts 23 and 24 prevent the deposit of glue onto the cylinders 21 and 22.

The rollers 5, 21 and 22 being made of silicone ensures that they elastically deform as sheet 2 tightens against film 4 and as panel 16 tightens against sheet 3, thus making the adhesion therebetween optimal.

During the step of lamination (i.e. of compression of film 4 against sheet 2 and of sheet 3 against panel 16), the cylinders 5 and 6 and the cylinders 21 and 22 rotate at a speed such as to cause the belts 6 and 7 and the belts 23 and 24 to slide at a speed preferably from 0.4 m/minute to 0.6 m/minute, and even more preferably of 0.5 m/minute.

According to the description provided for a preferred embodiment, it is obvious that some changes can be made by those skilled in the art without departing from the scope of the invention as defined by the following claims.