Apparatus for holding a planar workpiece and system and method for transporting a planar workpiece through a vessel of an apparatus for wet chemical processing - Patents.com

Abstract

A system for transporting planar workpieces (4; 32) through a bath of an apparatus for wet-chemically processing the workpieces (4; 32) includes a plurality of workpiece holding devices (1; 29). Each workpiece holding device (1; 29) includes at least one clamping device (2, 3; 30, 31) for holding the workpiece (4; 32) in a plane and a structure that surrounds a planar area (8) on at least three sides, viewed perpendicularly to the plane, when no workpiece is present. The structure includes first and second members (9; 34) and (10; 35) arranged on first and second sides of the area (8) and having respective longitudinal axes extending in a first direction (z) parallel to the plane. The system further includes a conveyor for transporting the workpiece holding devices (1; 29) in a second direction (x) parallel to the plane and transverse to the first direction (z). When viewed in the second direction (x), the longitudinal axis of the leading one of the first and second members (9,10; 34,35) of a first one of the workpiece holding devices (1; 29) and the longitudinal axes of the trailing members of the first and second members (9,10) of the next one of the workpiece holding devices (1; 29) in the second direction (x) are offset relative to the planes of these workpiece holding devices (1; 29) in opposite directions perpendicular to the plane, so that the leading member (9,10; 34,35) of the first workpiece holding device (1; 29) and the trailing member (9,10) of the next workpiece holding device (1; 29) at least partially face each other.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for holding a planar workpiece in a bath of an apparatus for wet chemical treatment of the workpiece, the apparatus comprising: at least one clamping device for holding the workpiece in a plane; a structure that encloses an area of the plane on at least three sides when viewed perpendicular to the plane and without a workpiece; the structure includes a first member and a second member disposed on first and second sides of the region and having respective longitudinal axes extending in a first direction parallel to the plane; the structure includes an interconnect interconnecting the first and second members on a third side of the region; at least one component for attaching the interconnect to a conveyor for transporting the device in a second direction parallel to the plane and transverse to the first direction; Includes:

[0002] The present invention also relates to a system for transporting a planar workpiece through a bath of an apparatus for wet chemical processing of the workpiece, The system includes a plurality of workpiece holding devices, each of which: at least one clamping device for holding the workpiece in a plane; a structure that encloses an area of the plane on at least three sides when viewed perpendicular to the plane and without a workpiece; Including, the structure includes a first member and a second member disposed on first and second sides of the region and having respective longitudinal axes extending in a first direction parallel to the plane; The system further includes a conveyor for transporting the workpiece holder in a second direction parallel to the plane and transverse to the first direction.

[0003] The present invention also relates to an apparatus for wet chemical processing of a planar workpiece.

[0004] The present invention also relates to a method of conveying a planar workpiece through a bath of an apparatus for wet chemical processing of the workpiece, comprising: A workpiece is mounted on each workpiece holding device, and each workpiece holding device is at least one clamping device for holding the workpiece in a plane; a structure that encloses an area of the plane on at least three sides when viewed perpendicular to the plane and without a workpiece; Including, the structure includes a first member and a second member disposed on first and second sides of the region and having respective longitudinal axes extending in a first direction parallel to the plane; The workpiece holding device is conveyed in a second direction parallel to the plane and transverse to the first direction, whereby the trailing edge of the first workpiece is separated from the leading edge of the second workpiece by a gap. [Background technology]

[0005] Chinese Utility Model No. 209428629 discloses a frame-like bracket for an electroplating machine, particularly suitable for carrier substrates (printed circuit boards) passing through the plating machine for processing. The bracket includes a horizontal bar, an opposing bar parallel to the horizontal bar, a right rod vertical in use (and thus perpendicular to the horizontal bar and bottom bar), and a left rod opposite the right rod and parallel to the right rod. The top bar, bottom bar, left rod, and right rod are connected to each other by two upper and lower connectors to form a rectangular frame-like structure. Multiple upper clamps are attached to the top bar for releasably gripping the top edge of the workpiece. Multiple bottom clamps are attached to the bottom bar for releasably gripping the bottom edge of the workpiece. One of the upper connectors is fixedly engaged (e.g., by welding) at or near the upper longitudinal end of the left rod. Similarly, the other upper connector is fixedly engaged at or near the upper longitudinal end of the right rod. Each top connector has a rectangular recess or groove to accommodate the longitudinal end of the top bar. The bottom connector is covered with an electrically insulating material. Both the left and right rods are cylindrical and electrically conductive. Because the left and right rods are electrically conductive, electroplating occurs on the left and right rods. This reduces the amount of metal plated on the left and right edges of the workpiece, thereby achieving better plating uniformity. Compared to vertical rods with rectangular cross sections, the cylindrical left and right rods do not induce localized currents during plating. The left and right rods are shown adjacent to the left and right edges of the workpiece, but are not shown exactly in the plane of the workpiece. Therefore, the effect achieved by the rods is not the same on the two surfaces of the workpiece. Furthermore, process uniformity is only achieved in electrochemical processes; the rods must be worn or replaced, and the position of the rods requires some spacing between successive workpieces mounted in brackets as they are transported through the plating bath. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide an apparatus, system, device and method of the type described above in the opening paragraph that allows for the surface treatment of workpieces that are conveyed in close succession so that a relatively uniform surface treatment is achieved at the leading and trailing edges of the workpieces on both sides of the workpiece. [Means for solving the problem]

[0007] This object is achieved in a first aspect by a device according to the invention, characterized in that the longitudinal axis is offset relative to the plane in the opposite direction to that perpendicular to the plane.

[0008] Because their longitudinal axes are offset in opposite directions perpendicular to the plane, the two holding devices can be transported closely in succession in the second direction, with only a small gap between the leading edge of the workpiece held by the upstream device and the trailing edge of the workpiece held by the downstream device. The leading one of the first and second members of the upstream holding device faces the trailing one of the first and second members of the downstream holding device across the gap. This creates a shielding effect in that the liquid in the bath cannot flow through the gap in large quantities. This prevents excessive processing, such as material deposition or removal, in areas near the edges of the workpiece's main surface. If the liquid is an electrolyte and the processing is electrochemical, less conductive liquid is present near the edge area. Therefore, the electric field lines are deflected away from the edge area.

[0009] The offset distances may be selected to optimize uniformity and may be adjustable in one embodiment.

[0010] The apparatus includes at least one clamping device for holding the workpiece in a plane. Typically, there are two or more clamping devices. They may be positioned along one or more edges of the region. By their configuration and position, the clamping devices define a plane, and therefore their position and orientation can be determined even when a workpiece is not present. The clamping devices are generally configured to grip the workpiece at one or more edges of the workpiece such that the arms of the clamping devices engage a major surface of the workpiece near one or more edges of the workpiece. In the case of a rectangular workpiece, the clamping devices may be positioned to engage the workpiece along only one or two edges of the workpiece. This may include, for example, an edge proximal to the interconnect and, optionally, an opposite edge.

[0011] The structure included in the apparatus surrounds at least three sides of the area of the plane when viewed perpendicular to the plane. The area generally does not exactly correspond to the complete area of the plane occupied by the workpiece. When viewing the plane in a direction perpendicular to the plane, in the absence of the workpiece, the structure appears to surround the area on at least three sides. Note, however, that the structure generally does not lie within the plane. In particular, the first member and the second member are offset relative to the plane, such that the first member and the second member may intersect the plane, but generally do not intersect.

[0012] The structure includes a first member and a second member disposed on first and second sides of the region, each having a longitudinal axis extending in a first direction parallel to the plane. Here, the terms "first side" and "second side" refer to the appearance of an observer when viewing the plane in a direction perpendicular to the plane, in the absence of a workpiece. In the presence of a workpiece, only one of the first and second members is generally fully visible, since the other is at least partially behind the workpiece. The first and second members generally have corresponding shapes and dimensions to achieve better uniformity of the flow field across both surfaces of the workpiece.

[0013] The structure includes an interconnection that interconnects the first and second members on the third side of the region. The interconnection need not be a single element, but may be an assembly. The interconnection can be attached to the conveyor by at least one part for attaching the interconnection to the conveyor. The attachment can be a hook or an arm. Thus, in use, the interconnection that interconnects the first and second members on the third side of the region is generally the upper interconnection. The third side is higher than the region. The apparatus can be thought of as a hanger for workpieces.

[0014] At least one component is provided for mounting the interconnection component to a conveyor for transporting the device in a second direction parallel to the plane and transverse to the first direction. The conveyor may include, for example, a chain or belt, or a shuttle on a guide rail or track. Thus, the direction of travel is such that one of the first and second components is at the leading edge of the workpiece and the other is at the trailing edge of the workpiece.

[0015] Because the longitudinal axes are offset relative to the plane in opposite directions perpendicular to the plane, as opposed to being offset in the same direction, the workpiece can be loaded and unloaded from one side using only one of the first and second members. This can include moving the workpiece along a track that includes a pivot about an axis parallel to the longitudinal axes of the first and second members. Also, by providing a holding device in which the longitudinal axes of the first and second members of the upstream holding device are offset in the same direction, a shielding effect can be achieved by having the leading one of the first and second members of the upstream holding device face the trailing one of the first and second members of the downstream holding device across a gap between the edge of the workpiece. In this case, every other device is rotated to face in the opposite direction from the adjacent holding device. However, every other holding device has both a first and second member so that the workpiece can be loaded or unloaded. Therefore, the workpiece cannot be loaded or unloaded from the same side of each device. In contrast, here, at least a portion of each of the first and second members between any attachment points to the components interconnecting the first and second members faces open space in the direction of the plane, which open space is available for manipulating the workpiece.

[0016] In one embodiment, the interconnect is releasably connected to at least one of the first and second members by a respective locking device, and the position of engagement between the locking device and the associated one of the first and second members is variable in a first direction.

[0017] This provides a simple method for adjusting the structure to workpieces of varying dimensions in a first direction. The structure can remain relatively rigid. To allow for variation in other dimensions, the interconnects can be an assembly of parts whose relative positions are adjustable to adjust the dimension of the interconnects parallel to a second direction.

[0018] In one embodiment, at least one of the at least one clamping device is supported by the interconnect.

[0019] The interconnectors are for attachment to the conveyor. Thus, the load of the workpiece is transferred to the conveyor via the clamping devices and the interconnectors. The first and second members only need to be load-bearing to a limited extent. Furthermore, in embodiments where the clamping devices are provided only on one or both sides of the area other than the area where the first and second members are located, as viewed perpendicular to the plane, the shielding effect is not impeded by the clamping devices. Limiting the number of sides on which the clamping devices are provided also simplifies the attachment and detachment of workpieces to and from the device.

[0020] In one embodiment, the interconnect includes a third member extending in the second direction, the first and second members being connected to the third member at opposite ends of the third member.

[0021] In this embodiment, the structure is relatively simple and strong. The third member need not be, and generally is not, rod-shaped.

[0022] In one example embodiment in which at least one of the at least one clamping devices is supported by an interconnect, the interconnect includes a third member extending in the second direction, the first and second members are connected to the third member at opposite ends of the third member, and the clamping device supported by the interconnect is supported by the third member.

[0023] This further simplifies the interconnections.

[0024] In one example of any embodiment in which at least one of the at least one clamping device is supported by the interconnect, the clamping device supported by the interconnect is journaled for movement in a first direction relative to the interconnect, and the device includes at least one biasing device for biasing the journaled clamping device for movement in the first direction away from the region.

[0025] An effect is that workpiece loading and unloading is simplified because the clamping device can be moved toward an area past the edge of the workpiece in an unclamped configuration, grip the workpiece, and then release. To unload, the grip is released and the clamping device automatically moves out of the way. In embodiments in which the workpiece is gripped by the clamping device at opposing edges, relatively flexible workpieces can be held under tension to maintain their surfaces flat, thus providing a more uniform surface treatment.

[0026] In one example of any embodiment in which at least one of the at least one clamping devices is supported by an interconnect, the clamping device supported by the interconnect is journaled for movement in a first direction relative to the interconnect, the device includes at least one biasing device for biasing the journaled clamping device for movement in the first direction away from the region, and the multiple clamping devices are mounted on a single common support member journaled for movement in the first direction relative to the interconnect, and the at least one biasing device acts on the common support member.

[0027] This makes it easier to move all of the clamping devices supported by the interconnected components together and provide uniform tension on the workpiece. Furthermore, there can be a relatively large number of clamping devices and few biasing devices, resulting in a savings in components. The biasing devices may be pre-tensioned, in which case the level of pre-tension may be adjustable. The biasing devices may include, for example, any type of resilient device (such as a spiral spring, a leaf spring, an elastomeric structure, etc.) or a gas spring.

[0028] In one embodiment of the device, the structure includes a further interconnection interconnecting the first member and the second member and located on a fourth side of the region.

[0029] This makes the structure more rigid and facilitates maintaining the first and second members in the correct orientation and position. Additionally, the further interconnects can function to support other portions of the device, such as one or more of the clamping devices. Generally, the fourth side is lower than the region, such that the further interconnects are lower interconnects compared to the interconnects on the third (opposite) side of the region, which are upper interconnects.

[0030] In one example of any embodiment in which the structure interconnects the first and second members and includes a further interconnection located on a fourth side of the region, the further interconnection is releasably connected to at least one of the first and second members by a respective locking device, and the position of engagement between the locking device and the associated one of the first and second members is variable in a first direction.

[0031] In this embodiment, the dimensions of the device parallel to the first direction can be adjusted, which may be required to adapt the device to different types of tanks, different conveyor positions, or workpieces of different sizes with corresponding dimensions.

[0032] In one example of any embodiment in which the structure interconnects the first and second members and includes a further interconnection located on a fourth side of the region, the further interconnection includes a further member extending in the second direction, and the first and second members are connected to the further member at opposing ends of the further member.

[0033] This makes further interconnections easier. The device is easier to operate, especially since the fourth side is generally the bottom and is therefore submerged in the tank near its bottom. The straight members are less likely to collide with or get caught on components located at the bottom of the tank.

[0034] In one example of any embodiment in which the structure interconnects the first and second members and includes a further interconnection portion located on a fourth side of the region, the further interconnection portion includes at least one follower portion for engaging a guide that defines a path through the vessel in the second direction.

[0035] In particular, in an apparatus for electrochemical surface treatment of workpieces, the guide assists the conveyor in holding the workpiece surface at a predetermined distance relative to an electrode disposed in a bath of the apparatus. Furthermore, the conveyor and the components for attaching the interconnecting components to the conveyor can be of lighter construction without increasing the risk of shaking of the apparatus and workpieces.

[0036] In one example of any embodiment in which the structure interconnects the first member and the second member and includes a further interconnect located on a fourth side of the region, at least one of the clamping devices is supported by the further interconnect.

[0037] This helps to reduce movement, especially rocking, of the workpiece relative to the device. Additionally, the workpiece can be tensioned in a first direction. This allows the device to hold relatively thin, flexible workpieces, such as foils.

[0038] In one embodiment of the device, the first and second members are rod-shaped along at least a majority of their respective lengths.

[0039] In this embodiment, it is relatively easy to manipulate the workpiece relative to the device during installation and removal. The risk of the workpiece striking the first or second member is low. Furthermore, the shielding effect provided by the first and second members is relatively uniform in the first direction. The majority of the first and second members may include a central longitudinal section, so that only the ends deviate from the rod shape, for example, because fastening devices or structures for engaging such devices are provided at the longitudinal ends of the first and second members.

[0040] In one example of any embodiment in which the first and second members are rod-shaped along at least a majority of their respective lengths, the first and second members are cylindrical along at least a majority of their respective lengths.

[0041] This helps improve the uniformity of the shielding effect because the flow of liquid through the first and second members is relatively smooth. There is little or no vortex. Furthermore, the risk of serious damage is reduced if a workpiece is accidentally struck by the first or second member during loading or unloading.

[0042] In one embodiment of the device, at least the surfaces of the first and second members are formed of an electrically insulating material along at least the majority of their respective lengths.

[0043] This makes the device particularly suitable for use in combination with devices for electrochemical processing, such as plating or etching. The first and second members are not plated or weakened; they only provide a shielding effect that enhances the uniformity of processing of the workpiece surface in the edge region. The first and second members may be integrally made of an electrically insulating material (e.g., extruded or molded), may be co-molded with an outer layer of electrically insulating material, or may include a sheath of such material.

[0044] In one embodiment of the device, at least one of the first and second members is the only part of the structure extending from the interconnect in the first direction for the distance that the member extends on the side of the area in which it is located.

[0045] This ensures that the shielding effect between two consecutive devices is provided on one side of the gap between the workpiece edges by only one of the first and second members of one device, and on the other side by only one of the first and second members of the adjacent device. Structures that may impede the flow of liquids or electrochemical processing devices are avoided in an unpredictable manner, avoiding electric fields. Furthermore, this simplifies the manipulation of the workpiece relative to the devices during installation and removal. In particular, relative movement, including pivoting of the workpiece about an axis parallel to the longitudinal axes of the first and second members, is possible while the workpiece is positioned between the first and second members and traverses a plane. Here, the term "side" again refers to the perspective of an observer looking at the area in a direction perpendicular to the plane in which the clamping devices are positioned to hold the workpiece.

[0046] In one embodiment of the apparatus, the components for attaching the interconnect to the conveyor are configured to attach the interconnect to an overhead conveyor to suspend the apparatus from the overhead conveyor.

[0047] Therefore, the apparatus does not need to include components for transporting the apparatus through the bath at a position where it is likely to be immersed in the liquid of the bath of the apparatus for wet chemical processing.Raising and lowering can be achieved by changing the level at which the conveyor is located, rather than including the necessary components in the apparatus.

[0048] According to another aspect, the system according to the invention for transporting planar workpieces is characterized in that, when viewed in the second direction, the longitudinal axis of a leading one of the first and second members of the first workpiece holding device and the longitudinal axis of a trailing one of the first and second members of the next workpiece holding device in the second direction are offset relative to the respective planes of these workpiece holding devices in opposite directions perpendicular to the plane, such that the leading member of the first workpiece holding device and the trailing member of the next workpiece holding device at least partially face each other.

[0049] In one embodiment of the system, the workpiece holding devices are devices according to the invention, however, in another embodiment of the system, in each workpiece holding device, the first member and the second member are provided on the same side of the plane.

[0050] Thus, the system provides the same shielding effect for the edge regions of the workpieces that follow each other in the second direction. The leading one of the first and second members of the first workpiece holding device and the trailing one of the first and second members of the next workpiece holding device are opposed at least partially across a gap between the leading edge of the workpiece held by the first workpiece holding device and the trailing edge of the workpiece held by the second workpiece holding device. The first and second members generally have corresponding shapes and dimensions to achieve good uniformity of the flow field across both surfaces of the workpiece.

[0051] In one embodiment of the system in which the first and second members in each workpiece holding device are provided on the same side of the plane, in each workpiece holding device the structure includes an interconnection interconnecting the first and second members on a third side of the area, the interconnection being releasably connected to at least one of the first and second members by a respective locking device, and an engagement position between the locking device and the associated one of the first and second members being variable in a first direction.

[0052] This provides a simple method for adjusting the structure to workpieces of varying dimensions in a first direction. The structure can remain relatively rigid. To allow for variation in other dimensions, the interconnects can be an assembly of parts whose relative positions are adjustable to adjust the dimension of the interconnects parallel to a second direction.

[0053] To vary the other dimension, the interconnect may be an assembly of parts whose mutual position is adjustable to adjust the dimension of the interconnect parallel to the second direction.

[0054] In one example of any embodiment of the system in which, in each workpiece holding device, the first and second members are provided on the same side of the plane, in each workpiece holding device, the structure includes an interconnection interconnecting the first and second members on a third side of the region, and at least one of the at least one clamping device is supported by the interconnection.

[0055] The interconnectors are for attachment to the conveyor. Thus, the load of the workpiece is transferred to the conveyor via the clamping devices and the interconnectors. The first and second members only need to be load-bearing to a limited extent. Furthermore, in embodiments where the clamping devices are provided only on one or both sides of the area other than the area where the first and second members are located, as viewed perpendicular to the plane, the shielding effect is not impeded by the clamping devices. Limiting the number of sides on which the clamping devices are provided also simplifies the attachment and detachment of workpieces to and from the device.

[0056] In any example embodiment of the system where, in each workpiece holding device, the first and second members are provided on the same side of the plane, in each workpiece holding device, the structure includes a third member interconnecting the first and second members on a third side of the region, and the first and second members are connected to the third member at opposite ends of the third member.

[0057] In this embodiment, the structure is relatively simple and strong. The third member need not be, and generally is not, rod-shaped.

[0058] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, the structure includes an interconnection interconnecting the first and second members on a third side of the region, at least one of the at least one clamping device is supported by the interconnection, the structure includes a third member interconnecting the first and second members on the third side of the region, the first and second members are connected to the third member at opposite ends of the third member, and the clamping device supported by the interconnection is supported by the third member.

[0059] This further simplifies the interconnection.The clamping device does not need to be attached in a fixed position relative to the third member in this embodiment.

[0060] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, the structure includes an interconnection interconnecting the first and second members on a third side of the region, at least one of the at least one clamping device is supported by the interconnection, the clamping device supported by the interconnection is pivoted for movement in a first direction relative to the interconnection, and the workpiece holding device includes at least one biasing device for biasing the pivoted clamping device for movement in the first direction away from the region.

[0061] An effect is that workpiece loading and unloading is simplified because the clamping device can be moved toward an area past the edge of the workpiece in an unclamped configuration, grip the workpiece, and then release. To unload, the grip is released and the clamping device automatically moves out of the way. In embodiments in which the workpiece is gripped by the clamping device at opposing edges, relatively flexible workpieces can be held under tension to maintain their surfaces flat, thus providing a more uniform surface treatment.

[0062] In one example of any embodiment of the system in which the first and second members in each workpiece holding device are provided on the same side of the plane, the structure includes an interconnection interconnecting the first and second members on a third side of the region, at least one of the at least one clamping device is supported by the interconnection, the clamping device supported by the interconnection is journaled for movement in a first direction relative to the interconnection, the workpiece holding device includes at least one biasing device for biasing the journaled clamping device for movement away from the region in the first direction, and the multiple clamping devices are mounted on a single common support member journaled for movement in the first direction relative to the interconnection, and the at least one biasing device acts on the common support member.

[0063] This makes it easier to move all of the clamping devices supported by the interconnected components together and provide uniform tension on the workpiece. Furthermore, there can be a relatively large number of clamping devices and few biasing devices, resulting in a savings in components. The biasing devices may be pre-tensioned, in which case the level of pre-tension may be adjustable. The biasing devices may include, for example, any type of resilient device (such as a spiral spring, a leaf spring, an elastomeric structure, etc.) or a gas spring.

[0064] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, in each workpiece holding device the structure includes a first interconnection portion interconnecting the first and second members on a third side of the region and a further interconnection portion interconnecting the first and second members on a fourth side of the region.

[0065] This makes the structure more rigid and makes it easier to keep the first and second members in the correct orientation and position. Additionally, further interconnects can serve to support other parts of the device, such as one or more of the clamping devices.

[0066] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, the structure includes a first interconnection portion interconnecting the first and second members on a third side of the region and a further interconnection portion interconnecting the first and second members on a fourth side of the region, the further interconnection portion being releasably connected to at least one of the first and second members by a respective locking device, and a position of engagement between the locking device and the associated one of the first and second members being variable in the first direction.

[0067] In this embodiment, the dimensions of the workpiece holding device parallel to the first direction can be adjusted, which may be required to adapt the workpiece holding device to different types of tanks, different conveyor positions, or workpieces with corresponding dimensions of different sizes.

[0068] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, the structure includes a first interconnection portion interconnecting the first and second members on a third side of the region and a further interconnection portion interconnecting the first and second members on a fourth side of the region, the further interconnection portion including a further member extending in the second direction, the first and second members connected to the further member at opposing ends of the further member.

[0069] This makes further interconnections easier. The workpiece holding device is easier to manipulate, especially since the fourth side is generally lower and is therefore submerged in the bath near its bottom. A straight member reduces the risk of collision with or getting caught on a part located at the bottom of the bath.

[0070] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, the structure includes a first interconnection portion interconnecting the first and second members on a third side of the region and a further interconnection portion interconnecting the first and second members on a fourth side of the region, the further interconnection portion including at least one follower portion for engaging with a guide that defines a path through the tank in the second direction.

[0071] In particular, in an apparatus for electrochemical surface treatment of workpieces, the guide assists the conveyor in holding the workpiece surface at a predetermined distance relative to an electrode disposed in a bath of the apparatus. Furthermore, the conveyor and the components for attaching the interconnecting components to the conveyor can be of lighter construction without increasing the risk of rocking of the workpiece holding device and the workpiece.

[0072] In one example of any embodiment of the system in which the first and second members are provided on the same side of the plane in each workpiece holding device, the structure includes a first interconnection interconnecting the first and second members on a third side of the region and a further interconnection interconnecting the first and second members on a fourth side of the region, and at least one of the clamping devices is supported by the further interconnection.

[0073] This helps to restrict movement, particularly rocking movement, of the workpiece relative to the workpiece holding device. Additionally, the workpiece can be tensioned in a first direction. This allows the workpiece holding device to hold relatively thin, flexible workpieces, such as foils.

[0074] In one embodiment of the system in which the first and second members in each workpiece holding device are provided on the same side of a plane, the first and second members in each workpiece holding device are rod-shaped along at least a majority of their respective lengths.

[0075] In this embodiment, it is relatively easy to manipulate the workpiece relative to the workpiece holding device when attaching or detaching the workpiece. There is a low risk of the workpiece striking the first or second member. Furthermore, the shielding effect provided by the first and second members is relatively uniform in the first direction. The majority of the first and second members may include a central longitudinal section, so that only the ends deviate from the rod shape, for example, because fixing devices or structures for engaging such devices are provided at the longitudinal ends of the first and second members.

[0076] In one example of any embodiment of the system in which the first and second members are provided on the same side of a plane in each workpiece holding device, the first and second members are rod-shaped along at least a majority of their respective lengths, and the first and second members are cylindrical along at least a majority of their respective lengths.

[0077] This helps improve the uniformity of the shielding effect because the flow of liquid through the first and second members is relatively smooth. There is little or no vortex. Furthermore, the risk of serious damage is reduced if a workpiece is accidentally struck by the first or second member during loading or unloading.

[0078] In one embodiment of the system in which the first and second members in each workpiece holding device are provided on the same side of a plane, at least a surface of the first and second members in each workpiece holding device is formed of an electrically insulating material along at least a majority of their respective lengths.

[0079] This makes the system particularly suitable for use in combination with equipment for electrochemical processing, such as plating or etching. The first and second members are not plated or weakened; they only provide a shielding effect that enhances the uniformity of processing of the workpiece surface in the edge region. The first and second members may be integrally made of an electrically insulating material (e.g., extruded or molded), may be co-molded with an outer layer of electrically insulating material, or may include a sheath of such material.

[0080] In one embodiment of a system in which the first and second members are provided on the same side of the plane in each workpiece holding device, in each workpiece holding device at least one of the first and second members is the only part of the structure extending in the first direction from the interconnection for the distance that member extends on the side of the area in which it is provided.

[0081] This ensures that the shielding effect between two consecutive workpiece holding devices is provided on one side of the gap between the workpiece edges by only one of the first and second members of one workpiece holding device, and on the other side by only one of the first and second members of the adjacent workpiece holding device. Structures that may impede the flow of liquids or electrochemical processing devices are avoided in an unpredictable manner, avoiding electric fields. Furthermore, the handling of the workpiece relative to the workpiece holding devices during installation and removal is simplified. In particular, relative movement, including pivoting of the workpiece about an axis parallel to the longitudinal axes of the first and second members, is possible while the workpiece is positioned between the first and second members and traverses a plane. Here, the term "side" again refers to the perspective of an observer looking at the area in a direction perpendicular to the plane in which the clamping devices are positioned to hold the workpiece.

[0082] One embodiment of the system further includes at least one of a loading device for attaching a workpiece to one of the workpiece holding devices and an unloading device for removing a workpiece from one of the workpiece holding devices, wherein the loading device includes a manipulator for moving the workpiece and is configured to move the workpiece to a position in a plane where the first and second members at least partially overlap an edge region of the workpiece when viewed in a direction perpendicular to the plane, and the unloading device includes a manipulator for moving the workpiece and is configured to move the workpiece from a position in the plane where the first and second members at least partially overlap an edge region of the workpiece when viewed in a direction perpendicular to the plane, and the movement includes a pivot component about a pivot axis parallel to the longitudinal axes of the first and second members.

[0083] In particular, in embodiments where the workpiece holding device is an apparatus according to the present invention and at least the longitudinal axes of the first and second members are offset in opposite directions relative to the plane, the workpiece can be loaded and / or unloaded from the workpiece holding device from one side without removing the workpiece holding device from the conveyor. The pivoting movement allows the workpiece to be moved around the first and second members that would otherwise be in the way. Note that the loading device and unloading device may be the same device.

[0084] In an embodiment of the system, the conveyor is an overhead conveyor and the workpiece holding device is suspended from the overhead conveyor.

[0085] In this embodiment, because the workpiece is vertically oriented, it is relatively easy to ensure that the liquid flow field is similar on both sides of the workpiece. The gravitational effect on the flow field is equal on both sides. Furthermore, no part of the conveyor needs to be immersed in the liquid in the bath of the wet chemical processing device.

[0086] According to another aspect, an apparatus for wet-chemical treatment of planar workpieces according to the invention comprises at least one system according to the invention.

[0087] Wet chemical treatments can include rinsing, electroless plating, pickling, etc. The treatment can specifically include electrochemical treatments. In that case, the apparatus includes one or more electrodes disposed in the bath and at least one device for establishing a potential difference between one or both surfaces of the workpiece and the electrodes. At least one of the clamping devices of each workpiece holding device is then positioned in electrical contact with the surface of the workpiece and configured to electrically connect to the device for establishing the potential difference.

[0088] According to another aspect, the method according to the invention for transporting planar workpieces through a bath of an apparatus for wet-chemically processing workpieces is characterized in that a first member of a workpiece holding device on which a first workpiece is mounted and one of the first member and second member of a workpiece holding device on which a second workpiece is mounted face each other with a gap therebetween.

[0089] The method may comprise the use of a system according to the invention. Similarly, devices and systems according to the invention may be suitable for and / or configured to carry out methods according to the invention.

[0090] The invention will now be explained in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0091] [Figure 1] 1 is a cross-sectional view of an electroplating tank in a wet chemical treatment apparatus for planar workpieces. [Figure 2] FIG. 2 is a front view of a first workpiece holding device for holding a planar workpiece in a bath of the device. [Figure 3] FIG. 3 is a side view of the workpiece holding device shown in FIG. 2. [Figure 4]FIG. 4 is a front view of the pair of workpiece holding devices shown in FIGS. 2 and 3. [Figure 5] 5 is a detailed top view of adjacent end regions of the pair of workpiece holders of FIG. 4. [Figure 6] 6 is a perspective view of the lower region of the workpiece holding device of FIGS. 2 to 5 without a workpiece, in use. FIG. [Figure 7] 7 is a first perspective view of the upper region of the workpiece holding device of FIG. 6 in use without a workpiece; [Figure 8] 8 is a second perspective view of the upper region of the workpiece holding device of FIGS. 6 and 7 without a workpiece. FIG. [Figure 9] 9 is a view corresponding to FIG. 8, but showing a state in which the support member to which the clamping device is fixed has been removed. [Figure 10] FIG. 10 is a front view of the second workpiece holding device. [Figure 11] 11 is a perspective view of a lower region of the workpiece holding device of FIG. 10. [Figure 12] 12 is a side view of the upper region of the workpiece holding device of FIGS. 10 and 11. FIG. [Figure 13] FIG. 13 is a first perspective view of an upper region of the workpiece holding device of FIGS. 10-12. [Figure 14] FIG. 14 is a second perspective view of the upper region of the workpiece holding device of FIGS. 10 to 13. [Figure 15A] 1 is a schematic diagram showing a basic transport system including a first workpiece holding device. [Figure 15B] FIG. 1 is a schematic diagram showing a basic transport system including a second workpiece holding device. DETAILED DESCRIPTION OF THE INVENTION

[0092] The following describes two types of systems for conveying planar workpieces through one or more baths of an apparatus for wet chemical processing of the workpieces. The apparatus may be configured specifically for electrochemical processing of the workpieces, such as electroplating or etching, although the systems are not limited to use with such types of apparatus. The apparatus may also, or alternatively, be configured to perform stripping, cleaning, degreasing, etc.

[0093] Both systems include multiple workpiece holding devices, also known as fixtures, and a conveyor to which the workpiece holding devices are connected. The conveyor is an overhead conveyor, and the workpiece holding devices are suspended from the conveyor, allowing at least the lower regions of the workpiece holding devices and the workpieces to be submerged in one or more device baths. The workpieces are transported through the baths in a substantially upright orientation, moving in a direction parallel to the plane of the workpieces. While being transported through the at least one or more baths, the workpiece holding devices and the workpieces are positioned close to each other in the direction of movement, with the trailing edge of one of the workpieces slightly forward of the leading edge of the next workpiece. The gap between the leading and trailing edges is shielded on one side by (only) one of the two workpiece holding devices and on the other side by (only) the other of the two workpiece holding devices. The gap remains unobstructed by the workpiece holding devices, allowing the edges to move closer together. The shielding limits the amount of (fresh) processing liquid passing through the workpiece in the area adjacent to the edges. In one system, all workpiece holders are identical, but the placement of the shielding members is asymmetric with respect to the plane in which the workpiece lies and the plane across it. The members are offset in opposite directions with respect to the plane in which the workpiece lies. In the second system, the placement of the shielding members is the same for each workpiece holder, but the sides on which the shielding members are located alternately face in opposite directions during use.

[0094] The workpiece holding apparatus 1 for the first system (FIGS. 2-9, 15A) includes a plurality of upper clamping devices 2a-f (FIGS. 7-9) and a plurality of lower clamping devices 3a-f (FIG. 6) for holding a planar workpiece 4. In the illustrated embodiment, there are an equal number of upper clamping devices 2a-f and lower clamping devices 3a-f. In alternative embodiments, the numbers may be different. In particular, there may be fewer lower clamping devices 3a-f. If the workpiece 4 is relatively rigid or has a relatively large mass, the lower clamping devices 3a-f may be omitted.

[0095] In the illustrated embodiment, at least some of the clamping devices 2a-f, 3a-f are electrically positioned to contact at least one, e.g., both, major surfaces of the workpiece 4. If the processing of the workpiece includes electroplating, the processing device is configured to apply a potential difference that causes one or more surfaces of the workpiece 4 to function as a cathode. Anodes 5a, b (FIG. 1) are positioned within a tank 6 of the device. Spray bars 7a, 7b are positioned within the tank 6 to direct an electrolyte solution onto the workpiece 4.

[0096] In a typical electroplating apparatus, the surface of the workpiece 4 is pre-coated with a (thin) layer of conductive material, for example by vapor deposition. Thus, the workpiece 4 enters the tank 6 already with its surface in a conductive state. Thus, in one embodiment, only the upper clamping device 2 may be electrically positioned to contact one or both major surfaces of the workpiece 4. In such an embodiment, the lower clamping devices 3a-f simply hold the workpiece 4.

[0097] The clamping devices 2 a - f, 3 a - f, through their position and configuration, define a plane in which the workpiece 4 lies when held by the workpiece holding device 1.

[0098] The workpiece holding device 1 includes a structure that, when viewed perpendicular to the plane, surrounds a planar area 8 on at least three sides (FIG. 2). However, area 8 does not correspond to the complete area occupied by the workpiece 4 because a first member 9 and a second member 10 included in the structure overlap edge regions of the workpiece 4. The first and second members 9, 10 are disposed on first and second opposite sides of area 8 when viewed perpendicular to the plane. The first and second members 9, 10 have respective longitudinal axes extending in a first direction z parallel to the plane. This direction z corresponds to the upright or vertical orientation of these longitudinal axes in use. Movement in use is in a second direction x parallel to the plane and transverse to the first direction.

[0099] In the illustrated embodiment, when viewed perpendicular to the plane, a structure that surrounds region 8 on at least three sides actually surrounds region 8 on four sides, so that region 8 appears to be framed. The structure includes an upper interconnect 11 and a lower interconnect 12 (also referred to as a further interconnect). Upper clamping devices 2a-f are supported by upper interconnect 11. Lower clamping devices 3a-f are supported by lower interconnect 12.

[0100] First and second parts 13, 14 for attaching the upper interconnection part 11 to a conveyor (FIG. 7) are provided for attaching the upper interconnection part 11 to an overhead conveyor that transports the workpiece holding device 1 in the second direction x. The first and second parts 13, 14 for attaching the upper interconnection part 11 to a conveyor attach the workpiece holding device 1 to the conveyor so that the workpiece holding device 1 is suspended from the conveyor. In the illustrated embodiment, the first and second parts 13, 14 for attaching the upper interconnection part 11 to a conveyor are hooks. Other types of attachment are contemplated, and the number of such parts may vary.

[0101] At least the longitudinal axes of the first and second members 9, 10 are offset in opposite directions perpendicular to the plane. These directions are also perpendicular to the first and second directions z, x. In the illustrated embodiment, the first and second members 9, 10 are completely offset relative to the plane. They may be spaced apart from the plane by a distance equal to at least half the thickness of the workpiece 4 that the workpiece holding device 1, more specifically the clamping devices 2a-f, 3a-f, are configured to hold. This may be on the order of millimeters, e.g., at least 1, 2, or 5 mm.

[0102] In the illustrated embodiment, the upper interconnection 11 includes a third member 15 extending in the second direction x. The first member 9 and the second member 10 are connected to the third member 15 at opposite ends of the third member 15 by first and second fastening devices 16 and 17. In the illustrated embodiment, the first and second fastening devices 16 and 17 are configured to releasably connect the first and second members 9 and 10 to the third member 15, respectively. The engagement position between the fastening devices 16 and 17 and the first and second members 9 and 10 is variable along the first direction z, in this case along the length of the first and second members 9 and 10. This allows the workpiece holding device 1 to accommodate workpieces 4 of different sizes, at least within a certain range. In the illustrated embodiment, the first and second fastening devices 16 and 17 are clamps. Alternatives that provide the same variability in the position of engagement are contemplated.

[0103] It is possible for the upper clamping devices 2a-f to be directly attached to the third member 15 in fixed positions. Instead, in the illustrated embodiment, the upper clamping devices 2a-f are attached to a single support member 18 in fixed positions relative to the support member 18. The support member 18 is journaled for movement in the first direction z relative to the third member 15. The biasing devices 19a-19c bias the support member 18, and therefore the upper clamping devices 2a-2f, in the first direction z away from the region 8. In the illustrated embodiment, the biasing devices 19a-19c act on the support member 18 and the third member 15. In the illustrated embodiment, the biasing devices 19a-19c are helical springs. In other embodiments, for example, gas springs can be used. In the illustrated embodiment, the biasing devices 19a-19c are pretensioned, and the pretension is adjustable.

[0104] The movably journaled support member 18 facilitates attachment of the workpiece 4 to the workpiece holding device 1. The biasing by the biasing devices 19a-19c also contributes to this effect, stretching the thin, flexible, planar workpiece 4 in the first direction z.

[0105] The lower interconnect 12 includes a fourth member 20 (FIG. 6) extending in the second direction x. The first member 9 and the second member 10 are connected to the fourth member 20 at opposite ends of the fourth member 20. The first and second members 9, 10 may be welded or otherwise joined to first and second mounting blocks 21, 22 (FIGS. 3 and 6) on either side of the fourth member 20 to define an offset relative to a plane in which the clamping devices 2, 3a-f are positioned to hold the workpiece 4.

[0106] The lower clamping devices 3a-f are attached to the fourth member 20 in fixed positions by fasteners, such as bolts or screws.

[0107] In other embodiments, mounting blocks 21, 22 may be replaced with fixing devices such as first and second fixing devices 16, 17. Additionally, lower clamping devices 3a-f may be journaled relative to fourth member 20 for movement in first direction z and biased in first direction z away from region 8.

[0108] In the illustrated embodiment, first and second followers 23, 24 in the form of guide rollers are attached to the fourth member 20 and project outwardly from the fourth member 20 in a first direction z. The followers 23, 24 interact with a guide 25 (FIG. 1) that defines a path through the tank 6 in the first direction x. Instead of guide rollers, other types of followers 23, 24 for engaging the guide 25 are contemplated.

[0109] In the illustrated embodiment, the first and second members 9, 10 are cylindrical with circular cross-sections. Other cross-sectional shapes, such as square, are also contemplated. The constant cross-sections at the ends of the first and second members 9, 10 over at least a portion of their lengths allow for variable engagement points with the first and second fastening devices 16, 17 used in the illustrated embodiment. The circular cross-sectional shapes allow for deflection with little risk of damage if the workpiece 4 contacts the first member 9 or the second member 10 during attachment or detachment of the workpiece 4 to or from the workpiece holding device 1. Additionally, movement of the workpiece holding device 1 in the second direction x is less likely to disrupt the flow of processing liquid over the surface of the workpiece 4.

[0110] In other embodiments, for example, embodiments not including first and second fixing devices 16, 17, one or more ends of the first and second members 9, 10 may deviate from the shape of a rod, while the central portions forming the majority of the length of the first and second members 9, 10 may be rod-shaped, for example cylindrical.

[0111] For electrochemical processing purposes, at least the surfaces of the first and second members 9, 10 are formed of an electrically insulating material along at least a majority of their respective lengths. This includes the central portions of the first and second members 9, 10. In one embodiment, the first and second members 9, 10 are made entirely of an electrically insulating material. Alternatively, they may be made of a metal or metal alloy and provided with an electrically insulating sheath or coating along at least a majority of their respective lengths. In all embodiments, the first and second members 9, 10 may be tubular, thereby saving weight. Additionally, an electrical cable may be disposed inside at least one of the first and second members 9, 10. This may be useful in embodiments in which the lower clamping devices 3a-f are configured to electrically contact one or both major surfaces of the workpiece 4. Similar advantages may be achieved if one or both of the first and second members 9, 10 have an electrically conductive core and an electrically insulating cladding.

[0112] In a system including at least two workpiece holding devices 1a, 1b (FIGS. 4, 5, 15A), successive workpiece holding devices 1a, 1b are mounted on the conveyor such that there is a gap between the leading edge 26 (FIG. 15A) of the workpiece 4a held by the upstream workpiece holding device 1a and the trailing edge 27b of the workpiece 4b held by the downstream workpiece holding device 1b. The first member 9a of the upstream workpiece holding device 1a faces the second member 10b of the downstream workpiece holding device 1b across a gap. This is because the first member 9a and the second member 10b are offset in opposite directions perpendicular to the plane in which the workpiece holding devices 1a, 1b are disposed to hold each workpiece 4a, 4b. In the illustrated embodiment, the distances by which the first member 9a and the second member 10b are offset relative to their respective planes are at least approximately equal.

[0113] When a potential difference is applied between the anodes 5a,b and the workpieces 4a,b, the first and second members 9a, 10b, which face each other across a gap between the leading edge 26a and the trailing edge 27b, provide a shielding effect. The electric field lines 28a,b are deflected away from the edge regions of the workpieces 4a,b. The offset distance to the plane on which the workpieces 4a,4b are held can be optimized for surface uniformity at the edges 26a,27b.

[0114] A loading and unloading device (not shown) is provided for attaching and detaching the workpiece 4 to and from each workpiece holding device 1. Each includes a manipulator for moving the workpiece 4. The workpiece holding devices 1a, b may be moved somewhat apart in the second direction x for attachment and detachment. The manipulator is configured to grasp the workpiece 4 and, in the case of the attachment device, move the workpiece 4 to an attachment position relative to the workpiece holding device 1. Similarly, the manipulator of the unloading device is configured to grasp the workpiece 4 and move the workpiece 4 from the attachment position relative to the workpiece holding device 1. At this time, the attachment device and unloading device are positioned adjacent to the workpiece holding device 1, opposite the plane on which the workpiece 4 is arranged to be held. Because the first member 9 and the second member 10 are offset in opposite directions, the workpiece 4 needs to move around only one of the first member 9 and the second member 10. This is done by a threading movement which includes a pivoting movement of the workpiece 4 about a pivot axis which is parallel to the longitudinal axis of the first and second members 9, 10. Thus, one of the leading and trailing edges 26, 27 of the workpiece 4 is moved rearward of one of the first and second members 9, 10 which is proximal to the plane in which the workpiece 4 is held, from the point of view of the associated mounting or unloading device. This means that the workpiece holding device 1 can remain attached to the conveyor during the mounting and unloading operations.

[0115] This is not the case for systems including a second workpiece holding device 29 (FIGS. 10-14, 15B) where all other workpiece holding devices 29 must be pivoted through 180° or where the loading and unloading devices are located on either side of the path of the workpiece holding device 29 and must operate on all other workpiece holding devices 29.

[0116] The second workpiece holding device 29 includes a plurality of upper clamping devices 30a-d (FIGS. 12-14) and a plurality of lower clamping devices 31a-d (FIG. 11) for holding a planar workpiece 32 (FIG. 15B). In the illustrated embodiment, there are an equal number of upper clamping devices 30a-30d and lower clamping devices 31a-31d. In alternative embodiments, the numbers may be different. In particular, there may be fewer lower clamping devices 31a-31d. If the workpiece 32 is relatively rigid or has a relatively large mass, the lower clamping devices 31a-31d may be omitted.

[0117] In the illustrated embodiment, at least some of the clamping devices 30a-d, 31a-d are electrically positioned to contact at least one, for example both, major surfaces of the workpiece 32.

[0118] The clamping devices 30a-d, 31a-d, through their position and configuration, define a plane in which the workpiece 32 lies when held by the workpiece holding device 29.

[0119] The workpiece holding device 29 includes a structure that, when viewed perpendicular to the plane, surrounds a planar area 33 on at least three sides (FIG. 10). The area 33 does not correspond to the complete area occupied by the workpiece 32. In use, the structure includes first and second members 34, 35 that overlap an edge area of the workpiece 32.

[0120] The first and second members 34, 35 are disposed on first and second opposite sides of the region 33 when viewed perpendicular to the plane. The first and second members 34, 35 have respective longitudinal axes extending in a first direction z parallel to the plane, which corresponds to the upright or perpendicular orientation of their longitudinal axes in use. Movement in use is in a second direction x parallel to the plane and transverse to the first direction.

[0121] In the illustrated embodiment, when viewed perpendicular to the plane, a structure that surrounds region 33 on at least three sides actually surrounds region 33 on four sides, so that region 33 appears to be framed. The structure includes an upper interconnect 36 and a lower interconnect 37 (also referred to as a further interconnect). Upper clamping devices 2a-d are supported by upper interconnect 36. Lower clamping devices 31a-d are supported by lower interconnect 37.

[0122] In the illustrated embodiment, a hanger arm 38 (FIG. 10) is attached to the upper interconnect 36. The hanger arm 38 is included in an overhead conveyor system for transporting the workpiece holding device 29 in the second direction x. The workpiece holding device 29 is suspended from the hanger arm 38. In an alternative embodiment, the second workpiece holding device 29 can be attached to the conveyor using hooks that form the first and second parts 13, 14 of the first workpiece holding device 1 for attaching the upper interconnect 11 of the first workpiece holding device 1 to the conveyor.

[0123] At least the longitudinal axes of the first and second members 34, 35 are offset relative to the plane, relative to a direction perpendicular to the plane. This direction is also perpendicular to the first and second directions z and x. In contrast to the first workpiece holding device 1, the first and second members 34, 35 of any one workpiece holding device 29 are offset in the same direction. They are therefore on the same side of the plane.

[0124] In the illustrated embodiment, the first and second members 34, 35 are fully offset relative to the plane. They may be spaced from the plane by a distance equal to at least half the thickness of the workpiece 32 that the workpiece holding device 29, and more specifically, the clamping devices 30a-d, 31a-d, are configured to hold. This may be a distance on the order of millimeters, for example, at least 1, 2, or 5 mm.

[0125] In the illustrated embodiment, the upper interconnect 36 includes a third member 39 ( FIGS. 10 , 13 , 14 ) extending in the second direction x. The first and second members 34, 35 are connected to the third member 39 at opposite ends thereof by mounting plates (not shown in detail) to which they are secured, for example, by welding. The mounting plates are secured to the third member 39 by fasteners (not shown), for example, screws. In alternative embodiments, the first and second members 34, 35 may be welded or adhesively bonded directly to the third member 39. In yet another alternative embodiment, fastening devices, such as fastening devices 16, 17 of the first workpiece holding device 1, may be used to vary the engagement position between the upper interconnect 36 and the first and second members 34, 35, respectively, in the first direction z.

[0126] The upper clamping devices 30a-d are attached to a support member 40 (FIG. 13) in a fixed position by fasteners, e.g., bolts or screws. The support member 40 is journaled for movement in a first direction z relative to the third member 39. The biasing devices 41a-c bias the support member 40, and thus the upper clamping devices 30a-f, in the first direction z away from the region 33. In the illustrated embodiment, the biasing devices 41a-c act on the support member 40 and the third member 39. In the illustrated embodiment, the biasing devices 41a-41c are helical springs. In other embodiments, for example, gas springs can be used. In the illustrated embodiment, the biasing devices 41a-41c are pretensioned, and the pretension is adjustable.

[0127] The movably journaled support member 40 facilitates attachment of the workpiece 32 to the workpiece holding device 29. The biasing by the biasing devices 41a-c also contributes to this effect, stretching the thin, flexible, planar workpiece 32 in the first direction z.

[0128] The lower interconnect 37 includes a fourth member 42 extending in the second direction x. The first member 34 and the second member 35 are connected to the fourth member 42 at opposite ends of the fourth member 42. The first and second members 34, 35 may be welded or otherwise joined to first and second mounting blocks attached to the fourth member 42 to define an offset relative to a plane in which the clamping devices 30a-d, 31a-d are positioned to hold the workpiece 32.

[0129] The lower clamping devices 31a-d are attached to the fourth member 42 in fixed positions by fasteners, such as bolts or screws.

[0130] In other embodiments, the mounting blocks may be replaced by fixtures such as the first and second fixtures 16, 17 of the first workpiece holding device 1.

[0131] In the illustrated embodiment, first and second followers 43, 44 (FIGS. 10, 11) are attached to the fourth member 42 and project outwardly from the fourth member 42 in the first direction z. The followers 43, 44 interact with a guide 25 (FIG. 1) that defines a path through the tank 6 in the first direction x. Again, types of followers 43, 44 other than guide rollers are contemplated for engaging the guide 25.

[0132] In the illustrated embodiment, the first and second members 34, 35 are cylindrically shaped with a circular cross-section over at least a majority of their respective lengths, including the central portion extending between the third member 39 and the fourth member 42. Other cross-sectional shapes, such as square, are also contemplated, particularly at one or both longitudinal ends of the first and second members 34, 35. A circular cross-sectional shape allows for deflection with little risk of damage if the workpiece 32 contacts the first or second members 34, 35 during loading or unloading from the workpiece holding device 29. It also minimizes disruption of the flow of processing fluid over the surface of the workpiece 32 as the workpiece holding device 29 moves in the second direction x. Other cross-sectional shapes may be more suitable for securing the ends of the first and second members 34, 35 to the third and fourth members 39, 42.

[0133] For electrochemical processing purposes, at least the surfaces of the first and second members 34, 35 are formed of an electrically insulating material along at least a majority of their respective lengths. This includes the central portions of each of the first and second members 34, 35. In one embodiment, the first and second members 34, 35 are made entirely of an electrically insulating material. Alternatively, they may be made of a metal or metal alloy and provided with an electrically insulating sheath or coating along at least a majority of their respective lengths. In all embodiments, the first and second members 34, 35 may be tubular, thereby conserving weight. Additionally, an electrical cable may be disposed inside at least one of the first and second members 34, 35. This may be useful in embodiments in which the lower clamping devices 31a-31d are configured to electrically contact one or both major surfaces of the workpiece 32. A similar effect can be achieved if one or both of the first and second members 34, 35 have an electrically conductive core and an electrically insulating cladding.

[0134] In a system including two second workpiece holding devices 29 (FIG. 15B), successive workpiece holding devices 29 are mounted on the conveyor such that a gap exists between the leading edge 45 of the workpiece 32a held by the upstream workpiece holding device 29 and the trailing edge 46b of the workpiece 32b held by the downstream workpiece holding device 29. The first member 34a of the upstream workpiece holding device 29 faces the second member 35b of the downstream workpiece holding device 29 across a gap. This is because the two workpiece holding devices 29 face in opposite directions, and the first member 34a and the second member 35b are offset in opposite directions perpendicular to the plane in which the workpiece holding devices 29 are positioned to hold each workpiece 32a, b. The distances by which the first member 34a and the second member 35b are offset relative to their respective planes are at least approximately equal in the illustrated embodiment.

[0135] When a potential difference is applied between the anodes 5a,b and the workpieces 32a,b, the first and second members 34a, 35b, which face each other across a gap between the leading edge 45a and the trailing edge 46b, provide a shielding effect. The electric field lines 47a,b are deflected away from the edge regions of the workpieces 32a,b. The offset distance to the plane on which the workpieces 32a,b are held can be optimized for surface uniformity at the edges 45a, 46b.

[0136] The present invention is not limited to the above-described embodiments and can be modified within the scope of the appended claims. For example, the lower interconnection 12, 37 may be omitted and the upper interconnection 11, 36 may be formed as an assembly for holding the first and second members 9, 10; 34, 35 at a variable distance from each other in the second direction x. Methods for doing this are disclosed, for example, in WO 2018 / 225535. [Explanation of symbols]

[0137] 1 First workpiece holding device 2a~f; 30a~d Upper clamping device 3a~f; 31a~d Lower clamping device 4;32 workpiece 5a,b Anode 6 Tank 7a,b Spray bar 8;33 Planar area 9;34 First member 10;35 Second member 11;36 Upper Interconnect 12;37 Lower Interconnect 13 First part for attaching to conveyor 14 Second part for attachment to conveyor 15;39 Third member 16 First Fixation Device 17 Secondary Fixation Device 18;40 Support member 19a~c;41a~c Biasing device 20;42 Fourth member 21 First Mounting Block 22 Second Mounting Block 23;43 First follower 24;44 Second driven part 25 Guide 26;45 leading edge 27b;46 trailing edge 28a~d; 47a~d Electric field lines 29 Second workpiece holding device 38 Hanger Arm

Claims

1. 1. A device for holding a planar workpiece (4) in a bath of an apparatus for wet chemical treatment of the workpiece (4), comprising: at least one clamping device (2, 3) for holding the workpiece (4) in a plane; a structure surrounding said planar area (8) on at least three sides, viewed perpendicularly to said plane and in the absence of said workpiece; the structure includes a first member (9) and a second member (10) disposed on first and second sides of the region (8) and having respective longitudinal axes extending in a first direction (z) parallel to the plane; the structure includes an interconnection (11) interconnecting the first and second members (9, 10) on a third side of the region (8); at least one part (13) for attaching said interconnection (11) to a conveyor for transporting said device in a second direction (x) parallel to said plane and transverse to said first direction (z); Including, 10. The apparatus of claim 9, wherein said longitudinal axis is offset relative to said plane in a direction opposite to that perpendicular to said plane.

2. the interconnection (11) being releasably connected to at least one of the first and second members (9, 10) by respective fastening devices (16, 17); the engagement position of the fixing device (16, 17) with one of the associated first and second members (9, 10) is variable in the first direction (z); 10. The apparatus of claim 1.

3. At least one of the at least one clamping device (2) is supported by the interconnection (11); 3. The device according to claim 1 or 2.

4. the interconnection portion (11) includes a third member (15) extending in the second direction (x); The first and second members (9, 10) are connected to the third member (15) at both ends of the third member (15).

4. An apparatus according to any one of claims 1 to 3.

5. The clamping device (2) supported by the interconnection part (11) is supported by the third member (15).

5. The device according to claim 4, which relies on claim 3.

6. The clamping device (2) supported by the interconnection portion (11) is pivotally supported so as to move in the first direction (z) relative to the interconnection portion (11); the device includes at least one biasing device (19a-19c) for biasing the pivotally supported clamping device (2) to move in the first direction (z) away from the region (8), 6. The device according to claim 3 or 5.

7. a plurality of clamping devices (2) mounted on a single common support member (18) journalled for movement in the first direction (z) relative to the interconnection portion (11); said at least one biasing device (19a-19c) acting on said common support member (18); 7. The apparatus of claim 6.

8. the structure includes a further interconnection (12) interconnecting the first and second members (9, 10) and located on a fourth side of the region (8); 8. An apparatus according to any one of claims 1 to 7.

9. At least one of the clamping devices (3) is supported by the further interconnection (12), 9. The apparatus of claim 8.

10. 1. A system for conveying a planar workpiece (4; 32) through a bath of an apparatus for wet-chemical treatment of said workpiece (4; 32), comprising: The system comprises a plurality of workpiece holding devices (1; 29), each of which has: at least one clamping device (2, 3; 30, 31) for holding the workpiece (4; 32) in a plane; a structure surrounding said planar area (8) on at least three sides, viewed perpendicularly to said plane and in the absence of said workpiece; Including, the structure comprises a first member (9; 34) and a second member (10; 35) arranged on first and second sides of the region (8) and having respective longitudinal axes extending in a first direction (z) parallel to the plane, the system further comprises a conveyor for transporting the workpiece holding device (1; 29) in a second direction (x) parallel to the plane and transverse to the first direction (z), characterized in that, viewed in the second direction (x), the longitudinal axis of a leading one of the first and second members (9, 10; 34, 35) of a first one of the workpiece holding devices (1; 29) and the longitudinal axis of a trailing one of the first and second members (9, 10) of a next one of the workpiece holding devices (1; 29) in the second direction (x) are offset relative to the respective planes of these workpiece holding devices (1; 29) in opposite directions perpendicular to the plane, so that the leading member (9, 10; 34, 35) of the first workpiece holding device (1; 29) and the trailing member (9, 10) of the next workpiece holding device (1; 29) at least partially face each other, system.

11. The workpiece holding device (1) is a device according to any one of claims 1 to 9, The system of claim 10.

12. In each of the workpiece holding devices (29), the first and second members (34, 35) are provided on the same side of the plane. The system of claim 10.

13. the conveyor is an overhead conveyor and the workpiece holding device (1; 29) is suspended from the overhead conveyor; 13. A system according to any one of claims 10 to 12.

14. Apparatus for the wet-chemical treatment of planar workpieces (4; 32), comprising at least one system according to any one of claims 10 to 13.

15. 1. A method for conveying a planar workpiece (4; 32) through a bath of an apparatus for wet-chemical treatment of said workpiece, comprising: The workpieces (4; 32) are mounted in respective workpiece holding devices (1; 29), each workpiece holding device (1; 29) comprising: at least one clamping device (2, 3; 30, 31) for holding the workpiece (4; 32) in a plane; a structure surrounding said planar area (8; 33) on at least three sides, viewed perpendicularly to said plane and in the absence of said workpiece; Including, the structure comprises a first member (9; 34) and a second member (10; 35) arranged on first and second sides of the region (8; 33) and having respective longitudinal axes extending in a first direction (z) parallel to the plane, the workpiece holding device (1; 29) is conveyed in a second direction (x) parallel to the plane and transverse to the first direction (z), whereby a trailing edge (27; 46) of the first workpiece (4; 32) is separated from a leading edge (26; 45) of the second workpiece (4; 32) by a gap; the first workpiece (4; 32) is attached to one of the first and second members (9, 10; 34, 35) of the workpiece holding device (1; 29), and the second workpiece (4) is attached to one of the first and second members (9, 10; 34, 35) of the workpiece holding device (1; 29) opposite to each other across the gap. method.

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