NL2009678C2

NL2009678C2 - Solar panel manufacture.

Info

Publication number: NL2009678C2
Application number: NL2009678A
Authority: NL
Inventors: Jan Bakker; Jan Verschoor; Simon Hartigh
Original assignee: Eurotron B V
Priority date: 2012-10-22
Filing date: 2012-10-22
Publication date: 2014-04-23
Also published as: WO2014065658A1

Abstract

The solar panel manufacture comprises a step of patterning an electrically conductive foil with a predefined pattern. Thereto, a sheet with a carrier layer and the foil is secured on a table. A head with a milling means protruding from a gliding face of the head is provided, said head being movable across at least a portion of said table. The head is positioned at a height above the table, such that the milling means extend through the conductive foil without extending through the underlying carrier layer. The head is then moved relative to the table, wherein the head glides with its gliding surface over a surface of the sheet and wherein the milling means mill a track in the foil in accordance with the predefined pattern without patterning of the underlying carrier layer.

Description

Solar panel manufacture

FIELD OF THE INVENTION

The invention relates to a method of manufacture a panel, 5 particularly a solar panel , wherein a plurality of electronic components, particularly solar cells, is assembled to a sheet comprising an electrically conductive foil, comprising the steps of: - providing the sheet with a patterned conductive foil; 10 - assembling the electronic components to the sheet, such that an electrical connection is established between terminals on the electronic components and individual conductor patterns in the foil; - encapsulating the electronic components, so as to 15 establish the panel.

The invention further relates to a method of patterning the conductive foil, and to an apparatus for use therein.

BACKGROUND OF THE INVENTION

20 An assembly line for assembly of solar cells is for instance known from the manuscript Ά novel module assembly line using back contact solar cells' as published on the IEEE Photovoltaics Specialists Conference, San Diego, USA, from May 11-15, 2008, authors M. Spath, P.C. de Jong, I.J.

25 Bennett, T.P. Visser and J. Bakker. The assembly line

presented therein is suitable for handling extremely thin and fragile solar cells with thicknesses of less than 200 microns and even less than 150 microns. The assembly line allows an assembly process comprising the steps of as 30 outlined above. After the provision of an interconnect foil (more precisely a back sheet provided with a conductive foil), conductive material in the form of paste is deposited on the electrical conductors of the interconnect foil. A

2 pre-processed sheet of thermoplast material, such as polyethylenevinylacetate (EVA) is hereon provided. Then, the solar cells are assembled to the thermoplast material. Use is made of a pick and place unit for adequate positioning.

5 It further allows coupling of the cells to the conductive material. After provision of a further sheet of thermoplast material and a cover plate, the solar panel is laminated in a vacuum laminator while simultaneously forming connections between the contact pads of the solar cells and those of the 10 interconnect foil. The module assembly line is capable of assembling solar panels comprising 4x9 and 6 x 10 solar cells, each solar cell having a size of 156 x 156 mm2 (6x6 inch). Improved versions of the assembly line are capable of assembling even more solar cells per panel, for instance 15 6x12 solar cells, at a total size of 2 x 1 meter. The assembly line is designed for supporting any type of solar cells provided with contact pads at its rear side. Examples of such solar cells include Integrated Back Contact (IBC), Heterojunction with Intrinsic thin layer (HIT), Emitter Wrap 20 Through (EWT), Metallisation Wrap Through (MWT), Metallisation Wrap Around (MWA) solar cells.

The known assembly line of Eurotron comprises a plurality of stations. In a first station the interconnect foil is provided to a carrier table. The carrier table is movable by 25 means of a transport system so as to move the stack of foils through the stations. The carrier table is provided with vacuum means. In a second step, conductive material, such as conductive adhesive, is applied, for instance with screen printing. The subsequently provided first foil is provided 30 with through-holes in locations aligned to those of the conductive material. In a subsequent station precise alignment is achieved between the contact pads of the solar cells and the through-holes in the first foil. The aligned 3 solar cells are then positioned onto the contact pads. Further stations are designed for applying the second foil and the cover plate and for flipping the solar panel upside down. Thereafter, it is placed into a vacuum laminator. The 5 station for the flipping of the solar panel comprises a clamping system to avoid shifting or breakage of solar cells. Use of the assembly line provided good results in terms of yield (100%) and performance (small deviation from the average).

10 Notwithstanding the good performance of such solar panels, it turns out that there is a hurdle for the adoption of the manufacturing process for which Eurotron's assembly line is designed. This hurdle is effectively the price of the back sheet provided with the patterned interconnect or conductor 15 foil. Commercially available back sheets comprise a laminate of a carrier of polyvinylfluoride, an intermediate layer of PET and a copper conductor foil. The conductor foil is herein patterned by means of etching. An insulation coating is printed on top of the conductor foil. Conductive adhesive 20 is printed on the conductor foil for contact improvement. As is exemplified by W. Eerenstein et al., SolarCon/CPTIC China, 20-22 March 2012, Shanghai, China, potential routes for cost reduction relate to the choice of cheaper materials for use in the backsheet, and optionally the omission of 25 certain layers.

It is therefore an object to improve the manufacturing of the solar panel in relation to the back sheet. However, particular attention needs to be paid to reliability. The interconnect between the solar cell and the back sheet is 30 known as a vulnerable element in the lifetime of the solar panel due to so-called thermal cycling. This effect is due to differential thermal expansion between the silicon based solar cells and the polymer-based back sheet. As a result of 4 the differential expansion, interconnects at an edge of a solar cell are subject to higher forces than interconnects in the center of the solar cell. Furthermore, the cells are interconnects at the edge of the panel may be more sensitive 5 than those in the center.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, a method of patterning an electrically conductive foil with a predefined 10 pattern is provided, which method comprises the steps of: - providing a sheet with a carrier layer and the foil adhered to the carrier layer; - securing the sheet on a table; - providing a head with a milling means protruding from a 15 gliding face of the head, said head being movable across at least a portion of said table; - positioning the head at a height above the table, such that the milling means extend through the conductive foil without extending through the underlying carrier layer; 20 - moving the head relative to the table, wherein the head glides with its gliding surface over a surface of the sheet and wherein the milling means mill a track in the foil in accordance with the predefined pattern without patterning of the underlying carrier layer.

25 According to a second aspect of the invention, a method of manufacturing a panel, wherein a plurality of electronic components is assembled to a sheet comprising an electrically conductive foil in accordance with a predefined pattern, comprising the steps of: 30 - patterning the conductive foil in accordance the invention; - assembling the electronic components to the sheet, such that an electrical connection is established between 5 terminals on the electronic components and individual conductor patterns in the foil, and - encapsulating the electronic components, so as to establish the panel.

5 According to a third aspect of the invention, a head for use in the method of the invention is provided, comprising a gliding face for gliding across a surface of an object; a milling means protruding from the gliding surface for milling tracks into the object; a motor for driving the 10 milling means; and means for moving the head across the surface of the object, and towards and away from the surface of said object.

According to a fourth aspect of the invention, an apparatus is provided comprising a carrier table provided with 15 securing means for the sheet, and at least one head according to the invention, said head being coupled to a frame and being movable by means of moving means.

The inventors of the present invention have understood that milling may be used rather than etching for a cost-down of 20 the back sheet. However, the mere use of milling does not lead to appropriate results. It was found that the carrier foil easily has a thickness variation over 10%. With a typical thickness of the carrier layer in the order of 200 microns, and a significantly smaller thickness of the 25 conductor foil, for instance of less than 80 microns, preferably less than 50 microns, there is a significant risk that the milled conductor tracks would not be extending through the conductor foil over the full area of the sheet. That would lead to short circuits and malfunctioning of the 30 resulting panel. It is therefore not surprising that Eerenstein of the institute ECN only envisaged cheaper materials for a cost down rather than an alternative manufacturing of the sheet.

6

The invention is based on the insight that the head of the milling apparatus is to follow the surface of the sheet on a microscopic level. Thereto, the head is provided with a gliding surface for gliding over the surface. This moreover 5 increases speed of the milling process. If the extension of the milling means into the sheet would vary as a consequence of the thickness variation, the milling means would be subject to a variation in resistance that could give rise to shocks, and a higher risk of deviation from the predefined 10 pattern. This potential shocking and deviation should be compensated with a reduction in speed. Contrarily, with the invention, such speed reduction is not necessary. Rather, a sufficiently high speed can be chosen so as to ensure patterning within a suitable time span.

15 More precisely, in one suitable embodiment, the head follows the sheet surface such that the tip of the milling means, typically a milling cutter, just enters the layer under the conductor foil. This layer is suitably a separate adhesion layer. This layer typically comprises polymer material. This 20 accurate "control" of the depth reached by the rotating milling cutter substantially prevents that- polymer -material below the conductor foil is removed. Such removal of material below the conductor foil would be analogous to the phenomenon of underetching a stack of layers in the 25 course of etching. The "under-milling" is however deemed to be more problematic, since the viscous-fiber like nature of polymer material may give rise to large and uncontrollable material removal and possibly deformation of the sheet surface .

30 In one suitable embodiment, thereto, the gliding face is provided with at least one fluid aperture, through which a fluid can flow while the head is moved over the surface of the sheet. The fluid may be any type of gas, or even a 7 liquid, but is most suitably air. The air may be provided at increased pressure, but alternatively at atmospheric pressure. The benefit hereof is the generation of a fluid film, particularly an air film between the gliding face and 5 the sheet surface. Such fluid film has been found to improve the conformity of the gliding face with the sheet surface. Alternative solutions for the gliding across the surface are not excluded. For instance, the gliding face may be provided with distance keepers in the form of rollers, rolling balls 10 or the like. A further alternative could be the use of a hard slider without air.

In a further embodiment, the head is provided with a suction chamber to which a connection to a suction source may be coupled. The suction chamber has an aperture in the gliding 15 face, particularly directly around the milling means.

Therewith milled material may be removed. Such removal is beneficial so as to prevent generation of any short circuit due to any strings of conductive material remaining in a generated track. It moreover has the benefit that the 20 milling means remains clean, i.e. that the strings do not form a winding around the milling means, typically embodied as a pin-like element with sharp edges.

Alternatively, the head may be provided with waste containers rather than a connection to a suction source. The 25 suction chamber may then be shaped as a channel along the milling means. The suction of the milled material may then be generated by the rotation of the milling means itself. This suction may further be improved by optimizing the shape of the milling means, i.e. in that the shape induces already 30 an upward movement of the removed material. The suction may additionally or alternatively be generated by means of air available in the head, for instance as used to operate an air cylinder for moving the motor upward and downward so as 8 to ensure good accomodation of the head to the sheet surface. Rather than integrating a suction chamber in the head, suction could be applied separately, for instance in a follower head, which follows a path of the head with the 5 milling means. Such a solution appears more expensive.

The combination of a gliding face with an aperture to a suction chamber, and circumferential thereto one or more fluid apertures, has turned out to lead to excellent results, such that a conductor foil of a sheet could be 10 patterned effectively without errors or remaining conductive material so as to generate a short-circuit. The fluid film could herein be generated by virtue of the existence of a fluid chamber within the head, and without the need for application of pressurized air.

15 Form and shape of the gliding face are open for optimization. Suitably, the gliding face is free of any corners, more particularly sharp corners of an angle up to 90 degrees. The gliding face may be round, oval or the like. Furthermore, the gliding face may be provided with an edge 20 that is retracted relative to the main surface. The retracted edge, suitably a ring, thus lays at a larger distance from the sheet surface that the main surface. This appears beneficial for accomodation to height variations and/or for inlet of air into the fluid chamber.

25 In one embodiment, the head is provided with means for accomodating a vertical position of the head to the surface variation. This is particularly desired for the embodiment in which an air film is to be present between the gliding face and the sheet surface during use. This means may be 30 embodied, for instance in the form of a magnetic attraction in the head relative to an underlying table. An alternative implementation makes use of an air cylinder that provides 9 air under pressure. Such an air cylinder may be hydraulically or electrically operated.

In again another implementation, use is made of elastic forces, such as an elastic member. The elastic member may be 5 embodied as a layer in the head, for instance of a rubber-elastic or foam-type material. The elastic member may alternatively be embodied as a spring, so that a first and a second portion of the head may be mutually movable. The spring suitably has a spring constant that is optimized for 10 the materials of the sheet and the further design of the head, as well as the speed of the head over the surface. Rather than an elastic member as part of the head, the connection of the head to a support member could be made to comprise an elastic element.

15 The milling means are suitably provided with a spindle. The spindle is preferably a high-speed spindle. For instance, the spindle may have a rotation speed of more than 10, 000 rpm, for instance more than 25, 000 rpm or more than 50, 000 rpm or even 100,000 rpm or more. The combination of a high 20 speed spindle with the simultaneous suction has turned out to work well.

The suction chamber is preferably provided with a tip portion having a shape of a truncated cone. Such a shape primarily prevents accumulation of removed materials in 25 corners wherein the suction is less effective. Moreover, this shape leaves space for the provision of a the fluid chamber.

The head is typically movable in three dimensions by means of its connection to a frame. Suitably, the head is 30 connected to a support member with an ability of movement in a vertical direction, i.e. towards and away from the sheet surface. In case of the presence of more than one head, this 10 embodiment allows that the heads are movable towards and away from the sheet surface individually.

The support member is again coupled to moving means for movement across the sheet surface. In one suitable 5 embodiment, the support member is coupled to a bar with an ability of movement in one direction. The bar, which preferably extends from a first to an opposed second side of the sheet without touching the sheet, may then be translated as a whole in the other lateral direction (i.e. x versus y). 10 The connection of a head to a bar allows in a straightforward manner the provision of more than one head to one bar, therewith increasing overall speed. However, alternative configurations for coupling of the head to a frame and for movement across and towards or away from the 15 sheet surface are not excluded.

When using a plurality of heads, it is not deemed necessary that all of them are milling with the same speed or diameter. Particularly, for some features, such as an outer ring, a head with a milling means for a larger diameter 20 appears suitable. It will be clear that the exact arrangement of heads is subject to variation, and to the design of the conductive foil. Particularly, the apparatus and the method of the present invention allow a larger flexibility to the solar panel manufacturer. This is in view 25 thereof that the patterning is done in house and that the solar panel manufacturer thus have control over the pattern. Preferably, the apparatus is provided with testing means for testing that conductor patterns in the foil are individualized appropriately, so that no short-circuit is 30 formed. The testing is preferably carried out electrically, i.e. through the provision of electrodes to the individual patterns and the detection of any current between adjacent patterns. Visual inspection may be used alternatively or 11 additionally. Particularly, a visual inspection device, such as a movable light source, for instance a laser or LED may be used. More specifically, such a light source may be moved along a generated track which, on the basis of the electric 5 detection, comprises an error. The error may then be identified more quickly, and subsequently be corrected by renewed material removal.

In a further embodiment, the apparatus may be provided with a device for the printing of material onto the sheet with 10 the patterned conductor. Particularly, the generated tracks, i.e. channels, in the conductor foils may be filled with an insulating material. The printed material may further extend above and/or on top of the conductor patterns, so as to define a barrier. The filling of the tracks takes away a 15 potential risk of short circuit formation. This risk is that any conductive material such as conductive adhesive that is subsequently deposited on the patterned conductor would flow away into the channels. The risk effectively depends on the type of deposited material, and the details of the further 20 assembly process.

Suitably, such a printing device could be integrated into the patterning device, particularly before the sheet is removed from the carrier table. For instance, the printing device could be coupled to the same frame.

25 After completion of the patterning step, the sheet may be transferred to a subsequent station in an assembly line for a subsequent step in the assembly process, such as the provision of conductive means on predefined locations on the conductor patterns, or the provision of a first foil of 30 insulating material on top of the sheet. Suitable subsequent steps are known from a.o. W02011154025, which is included herein by reference.

12

In one embodiment, the transfer process is embodied by removal of the sheet from the carrier table and transfer to another carrier table.

In an alternative embodiment, the process is embodied in 5 that the sheet is transported on the carrier table to a subsequent station. Preferably, then, the sheet remains on the carrier table throughout the assembly process. This embodiment has the advantage that the carrier foil of the sheet looses its function to carry a patterned foil.

10 Particularly in that case, the carrier foil may be reduced in thickness, for instance to at most 150 microns, more preferably at most 100 microns. This will further reduce the cost price of the sheet. For this embodiment, it is most suitable that the carrier table is movable, while the vacuum 15 remains. Fore the preceding embodiment with foil removal, the carrier table need not to be movable, or may be movable without the need to maintain the vacuum.

While the current method is foreseen to start with sheet having unpatterned conductor foils, it is not excluded that 20 the method is used for conductor foils that have been prepatterned, for instance on a very low resolution.

BRIEF INTRODUCTION OF THE FIGURES

These and other features of the invention will be further elucidated with reference to the figures, which are not 25 drawn to scale and are purely intended for illustrative purposes, in which:

Fig. 1 shows in a diagrammatical cross-sectional view a head in accordance with the invention, as coupled to a support member; 30 Fig. 2 shows in a diagrammatical cross-sectional view a combination of a head with a sheet applied on a carrier table; and 13

Fig. 3 shows in a diagrammatical cross-sectional view a second embodiment of a head.

Equal reference numerals in the figures refer to identical or equivalent elements.

5 DEFINTIONS

The term 'station' as used in the present application will be used interchangeably with 'assembly station' and is particularly referred to a station, wherein the moving of the mobile carrier table is interrupted and wherein 10 typically one step in the assembly method is carried out.

The term 'assembly line' herein refers to assembly equipment comprising a plurality of assembly stations. In a preferred embodiment, the device to be assembled is transported from one to a following assembly station by means of a mobile 15 carrier table.

The term 'encapsulant material' is herein used most broadly as a material known from the field of packaging of semiconductor components and similar electronic components. It may be a material suitable for use in underfill purposes, 20 for the application of a layer on the rear side of a slice of semiconductor material, as an encapsulating material (such as a polyimide). It is preferably elastic, but its structure and properties may be subject to change in any of the heat treatments. More specifically, the material is 25 flowable, i.e. as an underfill type material upon heating to a desired temperature, so as to fill any gaps between individual electronic components. While the first and second foils of encapsulant material are shown hereinafter to be applied separately, it is not excluded that at least one of 30 these foils is applied to a surface of an adjacent layer prior to the integration into the solar panel 30.

14 ELABORATED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT Fig. 1 shows in cross-sectional diagrammatical view a first embodiment of a head 10 according to the invention. The head 10 is held by a support member 40 that is provided with a 5 head fixation 45. The head comprises a spindle 13, within which a milling cutter 12 is present. The spindle 13 is driven by a motor 14. For the mechanical stability, a bearing ring 15 is present, either separately or as part of the motor. It goes without saying that the mechanical 10 construction of the head 10 can be further detailed by a skilled person using common general knowledge.

According to the invention the head 10 is provided with a gliding face 11. A tip 12a of milling cutter 12 protrudes from the gliding face 11 over a predefined distance. Such a 15 distance may be amended, for instance by exchange of the milling cutter 12. Alternative manners, such as the displacement in vertical direction of the spindle 13 are not excluded. An elastic member may be present in the head 10, which is however not indicated in the figure. The gliding 20 face 11 has for instance a round or oval shape. Its surface area is suitably at least 1 cm2, more preferably at least 3 cm2, for instance in the range of 5-50 cm2, such as 10-30 cm2. A retracted ring, not shown in the figure - may be present, but is not included in the above mentioned 25 dimensions. Such retracted ring is retracted in that its distance to a sheet surface is increased relative to that of the gliding face 11. The gliding face 11 is preferably made of a material with a smooth surface, for instance a metal or alloy such as steel or aluminum, or an engineering plastic, 30 suitably a rigid plastic.

Suitably, the head 10 is provided with a fluid chamber 31 and with fluid apertures 32 in the gliding face 11. These fluid chamber 31 and fluid apertures 32 serve to provide a 15 fluid film between the gliding face 11 and a sheet surface. In this example, the fluid is air. Air will be drawn into fluid chamber 31 by virtue of the movement of the head across the sheet surface. A separate air inlet may be 5 provided, for instance at a side face of the head 10. A pump may be present, and the fluid, such as air, may be provided at atmospheric pressure or higher pressure. Further design features may be provided for its optimization, as known per se also in the art as a bearing, such as a hydrostatic 10 bearing or particularly a hydrodynamic bearing.

More preferably, the head 10 is provided with a suction chamber 21 and with an aperture 22 thereto in the gliding face 11. The aperture 22 is most suitably located in a center of the gliding face 11, directly around the milling 15 cutter 12. This is most beneficial to apply the suction at the desired location, in the channel formed in the course of the milling process. It is however not excluded that more than one aperture 22 is present. The suction chamber 21 is provided with a tip portion substantially in the shape of a 20 truncated cone. This prevents accumulation of waste material. One or more tubes may be coupled to the suction chamber 21 by means of connection means 23. A suction source coupled to the connection means 23 will ensure the presence of a vacuum, sufficient for the desired suction.

25 Alternatively or additionally, suction source into the milled channel may be generated in that a motor 14 with an air cylinder is used. This air cylinder will bring the motor 14 upwards and/or downwards so as to follow the sheet surface 101, and thus also the gliding face 11 of the head 30 10 itself. The transport of the air into or out of the air cylinder may be exploited for providing suction.

The support member 40 is a construction part suitable for vertical movement, i.e. towards and away from the sheet 16 surface. The support member 40 is typically provides with a first shaft 41 and a second shaft 42. A rail 43 is present so as to allow variation in the height of the head 10. The height setting is controlled with height setting means 44.

5 While Fig. 1 merely locates a single head fixation 45, it is not excluded that the motor 14 is fixated separately.

Fig. 2 shows a system of a head 10 with a sheet 100 provided on a carrier table 60. The sheet 100 comprises a carrier foil 110, an adhesion layer 120 and a conductive foil 130, 10 and is provided with a sheet surface 101. Adhesive is typically present at the interfaces of said layers, and/or adhesive forces may be generated by chemical functionalisation of the polymers. This is known to the skilled person in the art of these commercially available 15 sheets. Commercially available sheets comprise a carrier foil of polyvinylfluoride (PVF) as traded by DuPont under the tradename Tedlar™. The thickness of the carrier foil is typically in the order of 200 microns. A further protection layer may be present on a bottom side of the carrier foil 20 110. In fact, said bottom side constitutes one of the surfaces of the resulting solar panel and is therefore suitably a moisture barrier. However, such a moisture barrier could be applied separately at the end of the assembly process.

25 The adhesion layer 120 is for instance made of PET

(polyethylene terephthalate), but may be an alternative material onto which a conductor foil is suitably deposited or fixated. The adhesion layer typically has a relatively small thickness of less than 25 microns. The adhesion layer 30 120 could further comprise a conductive polymer suitable as plating base for electroplating the subsequent conductive foil. The adhesion layer 120 typically includes an adhesive sublayer at its top side, at the interface with the 17 conductive foil. It is the intention of a most suitable embodiment of the method of the invention that the tip of the milling cutter does not extend through this adhesive sublayer. It goes without saying that the adhesion layer 120 5 may be limited to an adhesive sublayer. It is not even essential for the method of the invention that the sheet comprises an adhesion layer 120 at all. If no adhesion layer 120 is present, the tip 12a of the milling cutter 12 will reach the carrier layer 110.

10 The conductive foil 130 is suitably made of copper. An alternative conductor may be used instead or in addition.

For instance, use could be made of aluminum, an aluminum alloy, or a bilayer such as copper with a top layer of nickel. The thickness of the conductive foil is for instance 15 in the range of 20-50 microns. While the sheet 100 is shown in the Figure with a fully uniform thickness, this is not the case in practice, where a variation of 10%-20% within a sheet is not exceptional.

The sheet 100 is present on top of a carrier table 60. This 20 carrier table 60 is provided with securing means so as to ensure a correct and stable positioning of the sheet 100. In this embodiment, use is made of vacuum, for which chambers 61 are provided. The vacuum is exerted on the sheet 100 through apertures 62. Further means for application of the 25 vacuum such as pumps will be known per se, and a most suitable embodiment is indicated in EP2182549, which is a mobile carrier table suitable for moving said stack of foils in different stages of said method between stations for carrying out steps of the method. In one embodiment, it is 30 provided with vacuum means for local application of vacuum. It is observed for clarity that the term 'vacuum' as used in the context of the present invention refers to a situation of controlled underpressure relative to the atmospheric 18 pressure. Suitably, this pressure is 1 promille (0.1%) or less of the atmospheric pressure as known to the skilled person in the art. Preferably, the mobile carrier table comprises means for generating a vacuum - a vacuum generator 5 -, such as described in EP-A 2182549, which is included by reference herein. This known mobile carrier table is provided with vacuum chambers that allow the limitation of the vacuum to selected areas only (e.g. also referred to herein as local application of vacuum). In a most preferred 10 implementation disclosed in EP-A 2182549 use is made of a vacuum generator comprises one venturi device, and an overpressure tank is present. The venturi device is provided with a suction side and a pressure side, of which the suction side is connected to an aperture in the mobile 15 carrier table. The pressure side is connected to the overpressure tank. Such a mobile carrier table is typically made of metal such as steel or aluminum and intended for reuse .

According to the invention, the milling cutter 12 enters 20 through said sheet surface 101 into the sheet 100. It extends through the conductor layer 130, so that its tip 12a reaches into the adhesion layer 120. The head is provided with a gliding face 11 that glides across the sheet surface 101. In order to ensure that the tip 12a of the milling 25 cutter 12 reaches into the adhesion layer 120 notwithstanding the variation in thickness of the sheet 100, the head 10 follows the sheet surface 101 conformally. Thereto, the head 10 is provided with a gliding face 11. A fluid film 19, particularly an air film, develops and is 30 maintained between the gliding face 11 and the sheet surface 101. Small arrows in the figure indicate how air flows from the fluid chamber 31 through apertures 32 to the fluid film 19. Simultaneously, a suction source, coupled via tubes 24 19 to a suction chamber 21, suets milled material away. Large arrows in the figure indicate the flow of such milled material.

Fig. 3 shows a further embodiment ofa head 10. Indicated 5 herein is a waste container 25 for container removed material. The embodiment further shows a construction suitable for a high speed spindle, for instance of 30,000 rpm, and with air bearings 35 and a pressure feed 36 for the air bearings.

10 While the method of the invention is designed for sheets for use in the assembly of solar panels, particularly those with back contacted solar cells, the benefits of the method could be applied as well to the assembly of other panels, such as outdoor display panels and outdoor lighting panels. As will 15 be understood, the method is particularly suitable for large scale panels of a size of at least 1 m2.

20

List of reference numerals 10 head 11 gliding face 5 12 milling cutter 12a tip of milling cutter 13 spindle 14 motor 15 bearing ring 10 21 suction chamber 22 aperture to the suction chamber 23 connection means for a tube 24 tube 31 fluid chamber 15 32 fluid aperture 40 support member 41 first shaft 42 second shaft 43 rail 20 44 height setting means 45 head fixation 60 carrier table 61 internal cavity 62 aperture 25 100 sheet 101 sheet surface 110 carrier foil 120 adhesion layer 130 conductive foil

Claims

A method for patterning an electrically conductive film with a predetermined pattern, comprising the steps of:

2. Method as claimed in claim 1, wherein the sliding surface is provided with at least one opening 20 for fluid, through which the fluid can flow, while the head is moved over the surface of the sheet.

3. Method as claimed in claim 1 or 2, wherein an adhesive layer is present between the carrier layer and the conductive foil and wherein the head is positioned with respect to a length over which the milling means protrudes, that the milling means extends into the adhesive layer .

A method according to any one of the preceding claims, further comprising the step of removing milled conductor material by suction with a source under vacuum.

Method according to claim 4, wherein the head is provided with a suction chamber which is coupled to a suction source and is provided with an opening in the sliding surface, so that the conductor material is removed via the head.

5. Providing a sheet with a carrier layer and the foil. • Securing the sheet on a table; • Providing a head with a milling means protruding from a sliding surface of the head that is movable over at least a portion of the table; Positioning the head at a height above the table such that the milling means extends through the conductive film without extending through the underlying support layer; Applying a fluid film between the sliding surface of the head and the surface of the sheet from a chamber for the fluid of the head; Moving the head relative to the table, wherein the head slides with its sliding surface over a surface of the sheet and wherein the milling means mills a track in the film according to the predetermined pattern without patterning the underlying support layer.

6. Method as claimed in claim 5, wherein the one or more openings for fluid are located around the opening to the suction chamber.

The method of claim 1, wherein the fluid used is a gas, such as air.

8. Method as claimed in any of the foregoing claims, wherein the table comprises means for applying an underpressure via openings in a primary side thereof and wherein the sheet is fixed to the table by applying an underpressure in the table and to the sheet.

9. Method as claimed in any of the foregoing claims, wherein the sheet has an area of at least 1 m2.

A method according to any one of the preceding claims, wherein in the patterning is carried out with a plurality of heads which mill simultaneously.

A method according to any one of the preceding claims, further comprising a testing step for verifying that the individual conductor patterns made are electrically isolated from each other.

12. Method of manufacturing a panel, in which a plurality of electronic components are applied to a sheet containing an electrically conductive film with a predetermined pattern, which method comprises the steps of: • Patterning the conductor film according to one of the preceding claims; • Applying the electronic components to the sheet, such that an electrical connection is established between contacts on the electronic components and individual conductor patterns in the foil; • Enclosing the electronic components, whereby the panel is realized.

13. Method as claimed in claim 12, wherein the sheet is fixed in the patterning step to a table with means for applying an underpressure, which table is movable, and wherein the table is subsequently moved to a next station for performing a next one manufacturing step, wherein the table continues to serve as a carrier table for the sheet.

A head for use in a method according to any one of the preceding claims 1-11, 35 comprising: • A chamber for a pressurized fluid; A sliding surface for sliding over a surface of an object, with a first opening for the fluid therein, through which opening a film of the fluid can be created between the sliding surface and the surface of the object; 5. a milling means that protrudes above the sliding surface and which is intended for milling tracks in the object; • a motor for driving the milling means; Means for moving the head over the surface of the object, and towards and away from the surface of said object. 10

15. Head as claimed in claim 14, further comprising a suction chamber which is provided with a connector for a connection to a suction source and with an opening in the working surface, so that milled material can be removed through the opening and via the chamber.

The head of claim 14, wherein the milling means is in a spindle axis.

17. Head as claimed in claim 15, wherein the opening for the fluid is situated around the opening to the suction chamber.

The head of any one of claims 15 to 17, wherein the suction chamber includes an upper portion that is substantially in the form of a truncated cone.

The head of claim 18, wherein the fluid pressure chamber is located around the upper portion of the suction chamber. 25

The head of any one of claims 14 to 19, wherein the fluid is air, which is provided by means of an air line to the chamber for the pressurized fluid.

An apparatus for patterning a conductor film of a sheet, comprising: 30. a carrier table provided with fastening means for securing the sheet, and at least one head according to any of claims 14-20, which head is on a frame is coupled and is movable with the aid of movement means.

An apparatus according to claim 21, wherein the frame of the apparatus comprises a rod extending over the table from a first side to a second side, which rod is movable in a direction at least substantially perpendicular to an axis of the first side to the second side, and in which the head is coupled to the rod and is provided with first movement means for movement to and from the table and with second movement means for movement along the rod. 5

Apparatus as claimed in claim 21 or 22, wherein the securing means are means for providing an underpressure within the carrier table and on the sheet through openings in said carrier table.

The apparatus of claim 23, wherein the carrier table is movable between a first station and a second station, and wherein the means for providing the underpressure maintain an underpressure during said movement from the first to the second station.

25. Assembly line for the assembly of a solar panel comprising the device according to one of claims 21-24.