Abstract:
Solar cells are produced using a method for producing solar cells, wherein silicon containing vitreous substrates is provided, wherein each substrate is provided with an electrically conductive material on at least one side thereof. In the method, at least a portion of each substrate is successively transported through an electrolytic solution that is present in an electrolytic bath, and the electrically conductive material as the cathode is connected during the transport of the substrates through the electrolytic bath for the purpose of electrodepositing material from the electrolytic solution onto the electrically conductive material during said transport, wherein the substrates are suspended from a conveyor element during transport and extend in the transport direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority to International Patent Application No. PCT/NL2009/000083 filed 7 Apr. 2009, which further claims the benefit of priority to Dutch Patent Application No. 1035265 filed 7 Apr. 2008, the contents of which are incorporated herein by reference in their entirety. 
     The present invention relates to a method for producing solar cells, comprising the steps of 
     providing silicon containing vitreous substrates, each provided with an electrically conductive material on at least one side thereof, 
     successively transporting at least a portion of each substrate through an electrolytic solution that is present in an electrolytic bath, 
     connecting said electrically conductive material to act as the cathode during the transport of the substrates through the electrolytic bath for the purpose of electrodepositing material from the electrolytic solution onto the electrically conductive material during said transport. 
     The invention relates exclusively to a method for producing solar cells. At the moment at least, the manufacture of such solar cells mainly takes place on the basis of rectangular silicon panels. Such substrates typically have a thickness of only 50 to 300 μm and, also on account of the nature of the material, are very fragile and difficult to handle manually. A conductive track is frequently present on the silicon panel, on the side thereof where the light is incident, via which track electrons released in the silicon panel by incident light can be discharged, and which track forms part of an electrical circuit together with the connected load. For reasons of efficiency it is best if such tracks cover as little surface area of the silicon panel as possible. On the other hand, the cross-sectional area of the tracks must be adapted to deal with the electric current that is to pass through said tracks. 
     In the manufacture of solar cells it is known to use silicon panels as the substrates, to which a so-called seed layer of the electrically conductive material, such as Ag, is applied in the shape of the desired final track. Said seed layer is subsequently made thicker or higher through the addition of an electrically conductive material by means of an electrolytic or electroless plating process. An example of such a method, in which an electroplating process is used, is described in German patent application DE 10 2006 033 353 A1. The method described in the introduction relates to the method as described in said publication. 
     Said publication more specifically describes how substrates are passed through an electrolytic bath in a horizontal orientation, one behind the other. To that end, use is made of conveyor rollers arranged one behind the other, on which the substrates are supported, and of contact rollers disposed directly above said conveyor rollers, via which cathodic contact can be made with the tracks on the upper side of the substrate. The substrates move with the light incidence side facing downwards, just below the liquid level of an electrolytic solution in the electrolytic bath, so that the contact rollers extend only partially below the liquid level. Each contact roller is connected via an electrical switch to an electronic circuit which also comprises a rectifier and the anode. A control system ensures that the switch is only in the closed position (conductive state) during those moments in which the associated contact roller is in contact with a track. In addition to that, a blow nozzle is provided, which blows electrolytic solution away from the region of a contact roller so as to prevent the contact roller itself from being contaminated through electroplating. 
     The known method has a number of drawbacks. In the first place it is pointed out in this connection that the required electroplating apparatus requires a comparatively large floor area. In addition to that, the inevitable screening caused by the conveyor rollers will have an adverse effect on the quality of the electroplating process on that portion of the substrate where the substrate is conveyed over the conveyor rollers. Moreover, the process is comparatively difficult to control because of the required synchronisation of the switches and the blow nozzle on the one hand and the movement of the substrate through the electrolytic bath on the other hand. For reasons pertaining to the process, it is furthermore disadvantageous if the deposition rate is limited by the conductive capacity of the (semiconductor) substrate material. In practice this necessitates a comparatively long dwell time of the substrates in the electrolytic bath. 
     It is an object of the present invention to eliminate or at least alleviate the aforesaid drawbacks, which may or may not be realised by means of preferred embodiments of the invention. In order to achieve this object, the method according to the invention is in the first place characterised in that the substrates are suspended from a conveyor element during transport and extend in the transport direction. Since the substrates are transported in a suspended condition, the substrates are vertically oriented, and since the substrates extend in the transport direction, the electrolytic bath can be relatively narrow, thereby reducing the required floor area. In addition, since the substrates are conveyed in this suspended condition, a major portion of the surface area of the substrates remains clear and can thus be optimally electroplated. The invention is based on the surprising recognition that, in spite of the vulnerable nature of the vitreous substrates, which as a rule will have a maximum thickness of 500 .mu.m, said substrates can nevertheless be conveyed in the suspended condition through an electrolytic solution in an electrolytic bath. 
     Quite preferably, the substrates are freely suspended from the conveyor element during transport, so that no additional facilities, which may or may not move along with the substrates, are required for supporting the substrates in the bath. 
     When the present invention is used in the manufacture of solar cells, it is preferable if the electrically conductive material is applied to at least one side of the substrates in the form of at least one track. A limited number of main tracks can usually be distinguished in practice, and perpendicular thereto a larger number of parallel auxiliary tracks which intersect the main tracks. A solar cell often has two main tracks, while the auxiliary tracks are provided with an interspacing of between 3 and 5 mm. Because of the required current carrying capacity, the main tracks are significantly wider than the auxiliary tracks. 
     Advantageously, the substrate is clamped in at an upper edge thereof during transport by at least one clamping element that forms part of the conveyor element. 
     According to a further preferred embodiment the at least one track extends vertically and said at least one clamping element engages the substrate at an upper end of said at least one track for connecting this track as the cathode. The at least one vertically extending tracks preferably are busbars for the solar cell to be produced. Thus, said at least one clamping element is used not only for suspending the substrates therefrom but also for connecting the track as the cathode. 
     Preferably, furthermore, each substrate is clamped in at its upper edge during transport by means of not more and not fewer than two clamping elements that form part of the conveyor element. The use of exactly two clamping elements for each substrate offers the possibility of suspending the substrate in a stable manner, while it was also surprisingly found that the substrates, when fitted with exactly two clamping elements each, can move during their transport along an at least partly curved transport path in accordance with a further preferred embodiment. Such a curved transport path may be realised, for example, in that the conveyor element is guided around a transport wheel having a diameter of, for example, between 1.0 and 2.0 m, preferably approximately 1.5 m. 
     In a very advantageous embodiment, the substrates have their regions that are clamped in by the at least one clamping element located above the electrolytic solution. It is true that this implies that the portion of each substrate located above the electrolytic solution will not be electroplated, but at the same time this also holds for the clamping elements themselves, which can also be located above the electrolytic solution by virtue of this preferred embodiment. The at least one clamping element thus requires no or at least hardly any cleaning after a substrate has been guided through the electrolytic solution in the electrolytic bath by means of the at least one clamping element. 
     The present invention further relates to a device for producing solar cells, comprising an electrolytic bath for an electrolytic solution, transport means for transporting successive silicon containing substrates in a transport direction through the electrolytic solution, each substrate having an electrically conductive material provided on at least one side thereof, and contact means for connecting the tracks as cathodes during at least part of the transport. Such a device is known from the publication DE 10 2006 033 353 A1 cited above. The device according to the invention is characterised first of all in that the transport means comprise a conveyor element that is fitted with clamping elements designed to clamp in, by means of clamping ends thereof, an upper edge of a substrate so as to suspend said substrate, which clamping elements are at least in part also integral with the contact means, so that high electroplating currents are made possible and a high deposition rate of electroplating material can be achieved. 
     Quite preferably, the clamping elements are designed for freely suspending the substrate. 
     It is preferred that the conveyor element comprises a flexible tape of electrically conductive material that extends along a continuous horizontal track in order first to achieve a simple construction of the conveyor element and second to be able to use the conveyor element also for the necessary cathode connection of the electrically conductive material provided on the substrates. 
     For driving the conveyor element, advantageously, indentations are provided at regular intervals in the flexible tape, and the transport means further comprise at least one drive gear whose teeth engage said indentations. 
     If said indentations are rectangular and the teeth have an at least substantially triangular shape in horizontal cross-sections, an extremely stable and rectilinear transport of the substrates through the electrolytic solution can be obtained without even limited undulating movements of the substrates in vertical direction. 
     It is preferred inter alia for constructional reasons that each conveyor element comprises two parts, the lowermost ends of the respective two parts constituting the clamping ends. 
     To reduce the number of parts to be assembled it is advantageous if one of the two parts is integral with the flexible tape which one part preferably is a lip extending downwardly from a lower edge of the flexible tape. 
     Quite preferably, the clamping ends extend below a lower edge of the flexible tape, so that there is definitely no need for the flexible tape itself to pass through the electrolytic solution, which would necessitate a regular cleaning or etching of the flexible tape, irrespective of whether the clamping ends are located above or inside the electrolytic solution during electroplating of the substrates. 
     The above advantage does not only apply when producing solar cells but does also apply when substrates are electroplated in general. For this reason the present invention also relates to a device for electroplating substrates, comprising an electrolytic bath for an electrolytic solution, transport means for transporting successive substrates in a transport direction through the electrolytic solution, the transport means comprising a conveyor element that is fitted with a flexible tape of an electrically conductive material that extends along a continuous horizontal track and with clamping elements designed to clamp in, by means of clamping ends thereof, an upper edge of a substrate so as to suspend said substrate at least partly in said bath, in which the clamping ends extend below a lower edge of the flexible tape. 
     The use of two parts for each clamping element has the advantage for the process that it offers a possibility of connecting electrically conductive material on one or on both sides of the substrate to the cathode, as desired. It is advantageous in this connection if one of the two parts is made from an electrically conductive material and the other one of the two parts is at least partly made from an electrically insulating material. The part which at least partly is made from an electrically insulating material could for instance be made from a ceramic, a synthetic resin but could also be coated with an insulating layer. 
     It is constructionally advantageous, furthermore, if the two parts bear on one another under the influence of their own spring force. The clamping elements can thus be quickly assembled together with the conveyor element, but can also be quickly disassembled again, for example for replacing a clamping element. 
     To reduce mechanical loads on the substrates as much as possible, both while the loads enter the electrolytic bath and while they leave the electrolytic bath, a sloping slot, preferably a slot sloping in a direction opposed to the transport direction, is provided in at least one wall, more preferably in two mutually opposed walls, of the electrolytic bath. Such a sloping slot renders it possible for each substrate to be gradually entered into the electrolytic bath such that the upper side of each substrate is the first to enter the bath and/or is the first to leave the bath again. 
     A further possibility for reducing the mechanical loads on the substrates during traversing the electrolytic bath is offered in that panels with holes therein are provided at mutually opposed sides of the path followed by the substrates through the electrolytic bath. The panels as it were screen off the substrates against a too rough flow of the electrolytic solution, which is continuously circulated by a pump, as is known to those skilled in the art. 
     It is advantageous, furthermore, if an anode is provided between at least one of the panels and a wall of the electrolytic bath that extends parallel to said at least one panel, such that this anode itself definitely does not interfere with the flow of the electrolytic solution between said panels and the substrates. 
     The flow of the electrolytic solution in the immediate vicinity of the substrates can be further reduced in that at least one upright wall of the electrolytic bath is provided with an overflow edge for the electrolytic solution at the outer side of the panels. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention will be explained in more detail below with reference to a description of a preferred embodiment and to the accompanying figures, in which: 
         FIG. 1  is an isometric view of part of a preferred embodiment of a device according to the invention, wherewith at the same time the method according to the invention can be clarified; 
         FIG. 2  shows the device of  FIG. 1  in side elevation; 
         FIG. 3  shows the device of  FIG. 1  in a vertical sectional view; 
         FIG. 4  is an isometric view of part of a conveyor element as used in the device of  FIG. 1 , with substrates suspended therefrom; 
         FIG. 5  shows the conveyor element of  FIG. 4  in vertical sectional view; and 
         FIG. 6  shows the conveyor element of  FIG. 4  in an isometric view at the area of a transport wheel. 
     
    
    
     DETAILED DESCRIPTION 
     The  FIGS. 1 ,  2 , and  3  show (portions of) a preferred embodiment of a device according to the invention in various elevations and sectional views. The device  1  is designed for the electroplating of rectangular, panel-shaped substrates  2 . Specifically in the present invention, these substrates are composed of a non-metallic, vitreous material such as especially square silicon panels whose sides have a length of between approximately 125 mm and 210 mm and whose thickness lies between 50 μm and 300 μm. It is characteristic of this type of material that it is very vulnerable and is easily fractured. Such substrates are used in the manufacture of solar cells. In the present example, an electrically conductive material, here in the form of two (vertically oriented) straight main tracks  81  or busbars  81  and a larger number of (horizontally oriented) straight auxiliary tracks  82 , has been provided on one side of each substrate  2  (on the side facing the viewer in  FIGS. 1 and 2 ), for example by means of vapour deposition or printing, such that said auxiliary tracks  82  each intersect the main tracks  81  and accordingly are in electrical contact therewith. Prior to electroplating, the thickness of the main tracks  81  and the auxiliary tracks  82  is at most 5 μm, and preferably 2 to 3 μm, while the width of the auxiliary tracks  82  lies between 50 and 150 μm and preferably is approximately 80 μm. 
     The device  1  comprises an electrolytic bath  3  for an electrolytic solution with mutually opposed side walls  4 , mutually opposed end walls  5 , and a bottom  6 . The side wall  4  facing the viewer and the end wall  5  facing the viewer have not been shown in  FIG. 1  for the sake of clarity, so that the interior of the bath  3  is visible. Each end wall  5  is provided with two recesses  7 , each having two mutually facing U-shaped guide slots  8  by means of which a slide (not shown) can be accommodated in the recesses  7 . The upper edge of such a slide serves as an overflow and defines the liquid level of the electrolytic liquid in the bath  3 . A vertical feed tube  11  is provided for the supply of the electrolytic liquid, which is continuously circulated by pumping means (not shown) during operation, which feed tube  11  extends through the bottom  6  and issues inside the bath  3  adjacent the bottom  6  into a horizontal tube  12  which issues at two mutually opposed sides relative to the centre of the bath  3 , as is visible in  FIG. 3 . 
     Inside the bath  3 , furthermore, there is an anode  13  (not shown in  FIG. 2  for the sake of clarity) which extends parallel to one of the, side walls  4 . The anode  13  is planar and in fact has a grid shape, as is depicted in the right-hand bottom corner of  FIG. 1 . The anode  13  is suspended from two strips  14  which are (anodically) connected to a rectifier  16  (not shown) via inter alia a contact strip  15 . 
     Furthermore, two mutually opposed distributor plates  17 , which are yet to be described in more detail and which are provided with a regular, relatively dense pattern of holes  18 , are present inside the bath  3 . The space between the distributor plates  17  is to accommodate substrates  2 , i.e. the latter are to be transported through the electrolytic liquid in the bath  3  in this space. 
     The device  1  further comprises a continuous conveyor element  21 , which is yet to be described in more detail and from which substrates  2  can be suspended, for the transport of the substrates  2 . The frontmost end wall  5  is provided with a vertical slot  23  for affording the substrates  2  access to the bath, said substrates  2  being transported in the transport direction  22  by the continuous conveyor element  21 . Said slot  23  has an oblique orientation with respect to the transport direction  22 , such that the upper side of a substrate  2  will pass the slot  23  earlier than the lower side of the same substrate  2 . Thus each substrate  2  enters the bath  3  through the slot  23  in a gradual manner, which limits the mechanical loading of the substrate  2 . It should be borne in mind here that the electrolytic solution in bath  3  has a tendency to leave the bath  3  through the slot  23 . 
     To limit this outflow of electrolytic liquid through the slot  23  as much as possible, tubes (not shown) extending over the full height of the substrates are provided on either side of the substrate  2  at the area of the slot  23 . These tubes are provided inside the mutually facing U-shaped recesses  24  belonging to the sloping profiles  25  which jointly define the slot  23  and which form part of the respective end wall  5 . The tubes tend to move towards one another under the influence of the liquid pressure. While a substrate is passing through the slot  23 , said tubes will bear on mutually opposed sides of the substrate  2 , whereas the vertical slot can be fully closed by the tubes lying against each other when no substrate  2  is present in the slot  23 . The tubes can be positioned by a portion  65  of a strip part  55  or by the tape  51  (both to be described further below) such that the entry of substrates  2  can take place unhindered. 
     For exiting the bath  3 , a vertical slot is also provided in the opposite end wall  5 , which slot is oriented in parallel and can also be closed off by means of tubes. The slope of the slot at the exit side is such that the upper side of the substrate  2  leaves the bath through the relevant slot first and the lower side of the substrate  2  last. Thus there is a gradual emergence of the substrate  2  from the bath  3 , which limits the mechanical loading of the substrate. 
     While in the bath  3 , the substrate  2  is electrolytically treated. During this treatment the electrolytic solution is continuously circulated in the bath  3 , as was noted above. More in particular, purified electrolytic liquid enters the bath  3  through the two mutually opposed sides of the horizontal tube  12  at an angle of 45.degree. to the bottom  6  and the walls  4  and flows mainly in the direction of the mutually opposed side walls and from there in upward direction. Particularly at the side of the anode  13 , the electrolytic solution may be enriched with metal ions that are dissolved in the electrolytic solution from this anode. A comparatively large portion will subsequently leave the bath again over the upper edges of the slides provided in the recesses  7  at the upper sides of the end walls  5 . A limited amount of the electrolytic solution will enter the space between the distributor plates  17  through holes  18  in these distributor plates so as to contribute metal ions to the substrate  2  for the growth of the electrically conductive material present thereon. The use of the distributor plates  17  creates a comparatively quiet flow of electrolytic solution in the immediate vicinity of the substrates  2 , which reduces to a minimum mechanical loads on the substrates  2  caused by the flow of the electrolytic solution. 
     As was noted above, a continuous conveyor element  21  is used for transporting the substrates  2  through the bath  3 . The continuous conveyor element  21  comprises a continuous tape  51 , for example arranged around two transport wheels,  FIG. 6  showing a possible embodiment of a transport wheel  52 . The conveyor element  21  is guided by pairs of one gear  75  and one pressure roller  76  each, while the drive of the conveyor element  21  is provided by driven transport wheels such as wheel  52  in  FIG. 6  around which the conveyor element is tensioned. A pair  75 ,  76  is provided both upstream and downstream of the bath  3 . The gears  75  and pressure rollers  76  are made from a dielectric material. The teeth  78  of the gear  75  are an exception to this, they are made from a metal, such as stainless steel, on account of the favourable wear properties thereof. A groove  77  is provided in each pressure roller  76  at the same height as the teeth  78 , into which groove the teeth  78  extend at the side of the gear  75  facing the pressure roller. The tape  51  is provided at regular intervals with rectangular holes  79  which cooperate with the teeth  78  of the gears  75 . Thus the conveyor element  21  is guided. It is noted in this connection that the teeth  78  in cross-section are at least substantially triangular, so that the tape  51  remains at the same level during the cooperation mentioned above. To make the tape  51  more flexible in the present preferred embodiment, a vertical slit  88  extending from the hole  79 , or at least from every second hole  79 , right through to the upper edge of the tape  51  was opted for. 
     The continuous conveyor element  21  further comprises resilient clamping elements  53  at regular intervals. The pitch of these clamping elements  53  corresponds to the distance between two main tracks  81  on a substrate  2 . Furthermore, the substrates  2  are at a distance from one another such that adjoining main tracks  81  are also at the same pitch or distance. This renders it possible to grip each substrate  2  with clamping force by means of two clamping elements  53  adjacent the upper edge of the substrate  2  exactly in the locations of the two main tracks  81  of the relevant substrate  2 . 
     As in particular can be seen in  FIG. 5 , each clamping element  53  comprises two parts, i.e. a clip part  54  and a strip part  55 . The clip part  54  is in fact a bent strip comprising, from top to bottom, an upwardly bent finger  56 , a horizontal portion  57 , an oblique downward portion  58 , and a downwardly bent finger  59 . The horizontal portion  57  and the oblique downward portion  58  enclose an angle of approximately 45°. The horizontal portion  57  is passed through a narrow horizontal passage  60  in the continuous tape  51  adjacent the upwardly bent finger  56 . Such narrow passages  60  are provided at regular intervals over the full length of the continuous tape  51 . 
     The strip part  55  is a little wider than the strip from which the clip part  54  was manufactured. The strip part  55  extends vertically, except for a slight offset bend  61 . The portion  64  of the strip part  55  situated above the offset bend  61  extends parallel to the continuous tape  51 , whereas the portion  65  of the strip part  55  situated below the offset bend  61  lies in line with this tape. The strip part  55  is provided with an upwardly bent tag  62  just above the offset bend  61 , which tag enters a recess (not visible in the figures) provided in the lower edge of the continuous tape  51  at the area of each clamping element  53 . A hole  63 , through which the oblique downward portion  58  of the clip part  54  is passed close to the downwardly bent finger  59 , is provided in the strip part  55  partly above and partly below the offset bend  61 . The substrate  2  is now clamped in between the downwardly bent finger  59  of the clip part  54  and the portion of the strip part  55  located below the hole  63 . 
     The conveyor element  21  is automatically loaded with substrates  2 . At a loading station, substrates  2 , stacked below and next to the track of the conveyor element  21 , are presented to convex vacuum grippers. These vacuum grippers take an uppermost substrate  2  from the stack and pivot it about their horizontal axis parallel to the transport direction  22  until the substrate  2  is in a vertical orientation as shown, for example, in  FIG. 1 . Two clamping elements  53  are opened at the loading station in that a stud present there presses in the direction of arrow  85  (not shown) against the oblique downward portion  58  of the clip part  54  while at the same time another stud blocks the strip part  55  at the area of arrow  86  and the tape  51  is held by a clamping mechanism. As a result, the downwardly bent finger  59  will move away from the lower portion  65  of the strip part  55  in an oblique upward direction against the resilience of the clip part  54 . As soon as this open condition has been achieved, manipulation means will position the vertically oriented substrate  2  against the lower portion  65  of the strip part  55 , during which the substrate  2  is moved along with the conveyor element  51  by the manipulation means. The studs mentioned above are subsequently moved away from the clamping element  53 , so that the clamping element  53  closes again, whereupon the action of the grippers on the substrate is ended. The cycle described above repeats itself continuously. To increase the capacity, the substrates may alternatively be fed from a number of stacks of substrates, for example two stacks, such that the uppermost substrates of the stacks are simultaneously suspended from the conveyor element. Discharging of the conveyor element takes place in the exactly opposite sequence. 
     It is important to note that the clamping parts of the clamping elements  53  extend below the tape  51 . This brings with it the major advantage that the tape  51  itself need not be immersed, not even in part, in the electrolytic solution while transporting the substrates  2  through the electrolytic solution in the bath  3 . This would imply, because of the cathode voltage on the tape  51 , that the tape  51  would also be electroplated, which would necessitate a thorough cyclical cleaning of the tape  51  to remove material deposited on the tape  51 . If it is desired that each substrate  2  is fully immersed in the electrolytic solution, the clamping parts of the clamping elements  53  will necessarily also be immersed in the electrolytic solution. These parts will then have to be cyclically thoroughly cleaned in as far as these parts are connected to the cathode. On the other hand, it may be highly advantageous alternatively to immerse the substrates  2  almost completely in the electrolytic solution, i.e. up to a level where the clamping elements  53  are still just above the electrolytic solution. This offers the advantage that the clamping elements themselves are not electrochemically treated. A disadvantage of this is that the portion of each substrate  2  located above the electrolytic solution is not treated either. The latter disadvantage, however, may be very limited in practice in view of the fact that the clamping elements  53  grip the substrates  2  very close to their upper edges. 
     The connection of the main tracks  81 , and also of the auxiliary tracks  82  via the main tracks  81 , to the cathode is effected through contact shoes  91  which are provided in fixed positions above the electrolytic bath  3  and which make a sliding conductive contact with both sides of the stainless steel continuous tape  51 . The contact shoes  91  are provided with pivoting blocks  92  at their lower sides, which blocks are capable of limited pivoting movements about horizontal pivot axes  93  that extend parallel to the transport direction  22 . The action of a tension spring  94  on arms  95 , each of which bears on the outer side of a respective pivoting block  92 , urges said pivoting blocks  92  and thus the contact shoes  91  towards one another. The contact shoes  91  are in electrical contact with the cathode side of the rectifier  16  via inter alia cables  96  and a contact strip  97 . 
     In the present example, the clip part  54  of each clamping element  53  is made from an electrically conductive material, such as stainless steel, so that the electrically conductive contact with an auxiliary track is established via the downwardly bent finger  59 . Electrically conductive contact between the clip part  54  and tape  51  is achieved by contact between horizontal portion  57  and tape  51  at the location of passage  60 . 
     If electroplating is to be obtained also at the other side of the substrate  2 , the strip part  55  will also have to be made from an electrically conductive material, and the lower end of the strip part  55  will then have to make electrically conductive contact with the electrically conductive material on the relevant side of the substrate  2 . 
     If electroplating is required at one side only, the strip part  55  should preferably be manufactured from an insulating material, such as a synthetic resin or ceramic, or at least should strip part  55  not be in electrical conductive contact with clip part  54  or with tape  51 . This would for instance be achieved if at the location of contact between substrate  2  and strip part  55 , strip part  55  would be provided with a contacting member which is made from an insulating material such as rubber or if a metallic strip part  55  would be used which would be coated with a insulating layer such as HALAR® ECTFE. 
     In particular an embodiment as described above having one of the strip part  55  and the clip part  54  being made from an electrically conductive material which one of the strip part  55  and the clip part  54  is also in electrically conducting contact with tape  51  and the other one of the strip part  55  and the clip part  54  being made from an electrically insulating material could very advantageously be used for plating (metallic) leadframes. Such a tape would result in a more homogeneous plating process with no or less Sn plating on tape  51 . Furthermore only the clip part  54  which would be plated as far as in electrolytic bath  3  would need regular cleaning. The life time of tape  51  would increase. 
     In an alternative embodiment strip part  55  or at least the lower part thereof which in  FIG. 5  is aligned with tape  51  there below, could be an integral part of the tape  51  and in that case clearly be made from a similar material. These integral parts would form lips which would extend downwardly from the lower edge  89  (not shown) of tape  51 .