Reference system for singulated work

Abstract

To provide a referencing system for singulated workpieces in which the size and weight are reduced without adversely affecting reliability or accuracy compared to conventional systems.SOLUTION: The invention provides a method and apparatus for referencing a plurality of singulated workpieces within a printer prior to performing a printing operation, permitting a single referencing plate to be used both for horizontal and vertical referencing operations.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to tooling for supporting a plurality of singulated works during a printing operation, a printer for printing print media onto the plurality of singulated works during a printing operation, and a method for referencing the plurality of singulated works in the printer prior to performing a printing operation. [Background technology]

[0002] Industrial screen printers typically apply a conductive print medium, such as solder paste, silver paste, or conductive ink, onto one or more planar workpieces, such as circuit boards, by applying the conductive print medium through an aperture pattern in a thin flat layer or mask, such as a stencil (which is a patterned solid material, such as stainless steel, for example), or a screen, which is a mesh material coated with an emulsion. The present invention is equally applicable to both screen and stencil printing, and for convenience, the term "stencil" is used throughout the remainder of this document to refer to any such patterned mask. The print medium is applied using an angle blade or squeegee. The same machine can also be used to print certain non-conductive media, such as glue or other adhesives, onto the workpiece.

[0003] When printing multiple individual "singulated" workpieces in a single printing operation, it is necessary to support each work individually while allowing the works to align in their planes, i.e., in the horizontal plane in a standard printing press. It is also typically necessary to reference the supports in the vertical or Z direction.

[0004] A system for supporting singulated workpieces is known, for example from US Pat. No. 5,399,633. This system uses multiple towers, one for each singulated workpiece arranged in an array on top of a vertically movable tooling table. Each tower has a head section at its distal end, which can be moved in a horizontal plane relative to the rest of the tower. This movement occurs by the actuation of a separate horizontal reference plate (often also known as an "active surround") during a horizontal referencing operation. Furthermore, each tower is lockably deformable in the Z direction. To achieve Z referencing, a vertical referencing operation is performed in which the tower is raised by the tooling table to engage and deform the lower surface of a vertical reference plate (often known as an "upper reference plate" or TRP) and is then locked at the referenced Z height (often known as a "Z lock"). It is clear that this upper reference plate needs to be moved away from the tooling so as not to interfere with subsequent printing operations.

[0005] While this system works well, it does have some drawbacks. Specifically, the TRP must be a large, rigid structure capable of absorbing the total upward force from all towers, which can be significant. For example, each tower may exert an upward force of up to about 1 kg. This, in turn, requires relatively large components to move the upper reference plate to and from a reference position above the towers. Furthermore, the Z-lock system must hold each tower to withstand a downward force of about 3 kg to 5 kg due to pressure exerted by the squeegee during printing operations. Thus, the size and weight of these components are large, and it is desirable to reduce their size and weight without adversely affecting reliability or accuracy. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2014 / 166956 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention is directed to overcoming these problems and provides a tooling system that is significantly reduced in weight and size. [Means for solving the problem]

[0008] According to the present invention, this object is achieved in two ways: i) Proposing a new type of Z-actuated locking mechanism for the tower, thereby significantly reducing the weight, size and generated Z forces. ii) Utilizing an active surround for the top reference completely eliminates the need for a separate top reference plate.

[0009] In this manner, a single reference plate may be utilized for both horizontal and vertical referencing operations.

[0010] According to a first aspect of the present invention, there is provided tooling for supporting a plurality of singulated workpieces during a printing operation, the tooling comprising a plurality of towers, each tower extending along an axis and configured to support each workpiece in the plurality of workpieces in a horizontal orientation, each tower comprising: Body and a head, the head having a support surface provided at a distal end thereof and configured to support each workpiece, the support surface being displaceable relative to the body in a plane perpendicular to the axis; Equipped with the body having a pneumatic input for receiving compressed air and applying a lifting force to the head to move the head along said axial direction relative to the body; Each tower includes a locking mechanism for selectively locking the head to the body.

[0011] According to a second aspect of the invention, there is provided a printer for printing print media onto a plurality of singulated works during a printing operation, the printer comprising tooling of the first aspect.

[0012] According to a third aspect of the present invention, there is provided a method of referencing a plurality of singulated workpieces in a printer prior to performance of a printing operation, the printer comprising tooling for supporting the singulated workpieces and a reference plate having a plurality of reference surfaces movable in a horizontal plane, the method comprising: i) supporting a workpiece on tooling in a horizontal orientation; ii) performing, in any order, vertical and horizontal referencing operations, a vertical referencing operation including lifting the supported workpiece into contact with a lower surface of the reference plate and then locking the tooling to hold the supported workpiece at a locked vertical distance from a base of the tooling; a horizontal referencing operation including lifting a work supported within a respective aperture formed in the reference plate and moving a reference surface in a horizontal plane into contact with each supported work; Includes.

[0013] Other specific aspects and features of the present invention are set forth in the accompanying claims.

[0014] The invention will now be described with reference to the accompanying drawings (not to scale). [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional side view of tooling according to one embodiment of the present invention, positioned below a reference plate; FIG. [Figure 2A] 1A-1D are schematic cross-sectional side views of the tower at various stages during vertical referencing operation; [Figure 2B] 1A-1D are schematic cross-sectional side views of the tower at various stages during vertical referencing operation; [Figure 2C] 1A-1D are schematic cross-sectional side views of the tower at various stages during vertical referencing operation; [Figure 3A] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3B] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3C] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3D] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3E] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3F] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3G] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3H] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3I] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3J] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3K] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3L] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3M] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3N] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3O] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3P] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3Q] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3R] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. [Figure 3S] FIG. 2 is a schematic diagram of a step in a reference method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In FIG. 1, an embodiment of the present invention is shown in a schematic manner. The printer 1 is shown with a tooling 2 attached, which is supported on a lift table 3 of the printer 1. Although not explicitly shown, it will be understood that the tooling 2 is therefore located below the printing area of ​​the printer 1, such that the stencil is located above the tooling 2 and may be acted upon by the squeegee of the print head during the printing operation. In use (and as is known per se in the art), a number of unprinted workpieces (not shown in FIG. 1) may enter the printer 1 in a carrier (not shown) and overlap the tooling 2. The lift table 3 is then driven vertically upwards (i.e. parallel to the positive Z direction shown) to lift the unprinted workpieces from the carrier and into contact with the stencil for the printing operation. After completion of the printing operation, the lift table 3 is then lowered to move the printed workpieces away from the stencil and back to the carrier for further transport from the printer 1.

[0017] The tooling 2 comprises a number of vertically oriented towers 4, i.e. each tower extends parallel to the Z-axis direction. Each tower 4 is configured to support a respective workpiece (not shown) among the plurality of workpieces in a horizontal orientation. Each tower 4 comprises a head 5 and a body 7, the body 7 supporting the head 5. The body is supported on a base 8 of the tooling 2, which is shared by all towers 4. The heads 5 each have a support surface 6 at their distal end, the support surface 6 each configured to support a workpiece. The support surface 6 is displaceable relative to the body 7 in a plane perpendicular to the axis, i.e. parallel to the horizontal XY plane shown. This displaceability can be realized in various ways. For example, in the aforementioned patent document 1, the support surface 6 is connected to the tower via an elastically deformable material, for example a rubber material or other elastomeric material. As will be explained in more detail below, this displaceability allows the support surface 6 and its respective workpiece to be displaced away from a "neutral" XY position by the reference plate 11 during a horizontal referencing operation, and then returned to this neutral position when the reference plate 11 is disengaged after the horizontal referencing operation. The tooling 2 allows the support surface 6 to be coupled to the head 5, for example, via an elastically deformable material (not shown), or alternative configurations (such as using a spring rather than an elastically deformable material) as will be apparent to those skilled in the art.

[0018] Furthermore, the head 5 is movable relative to the body 7 in a direction parallel to the Z-axis, i.e., in a vertical direction. To control this vertical movement of the head 5, the body 7 is provided with an air pressure input for receiving compressed air and applying a lifting force to the head, thereby moving the head 5 vertically upward relative to the body 7. The compressed air is delivered to the body 7 of each tower 4 via an air channel 9 provided in the base 8. The air channel 9 is connected to an air pressure source 10, such as a pump (not shown). In this way, as will be explained in more detail hereinafter, during a vertical referencing operation, air is supplied to each tower 4, thereby lifting each head 5 into contact with the lower surface of the reference plate 11, as shown in FIG. 1. Each tower 4 also includes a locking mechanism (not shown in FIG. 1) for selectively locking the head 5 relative to the body 7. The locking mechanism is applied in the position shown in FIG. 1 to lock the head 5 of each tower 4 in the vertical referencing position established by the lower surface of the reference plate 11. Thereby, the head 5 remains in this position when the tower 4 and reference plate 11 are moved apart, as will be explained further below.

[0019] Although not shown in FIG. 1, each tower may further comprise means for securing a workpiece onto the support surface 6, such as a vacuum source or a relatively low pressure source, essentially as known in the art and therefore not described in detail herein.

[0020] 2A-2C show schematic side cross-sectional views of the tower 4 at various stages during a vertical referencing operation, illustrating a locking mechanism according to an embodiment of the present invention. As shown, in this embodiment, the head 5 comprises an elongated stem extending along the axis of the tower 4, i.e. parallel to the Z-axis, with the support surface 6 located at the uppermost end of the elongated stem. The body 7 comprises a sleeve having a central aperture dimensioned to slidingly receive the stem therein along the axis. Compressed air from a pneumatic supply 10 (see FIG. 1) can be selectively introduced via a pneumatic port (not shown) into a lift cavity 12 located in the lower part of the sleeve below the stem. An air bearing 13 is provided in the aperture adjacent to the stem. This reduces the frictional forces between the stem and the air bearing when an air supply is supplied to the air bearing via a separate air passage (not shown), thereby allowing the stem to slide against the air bearing 13 parallel to the axis. When no air supply is supplied to the air bearing 13, the stem is locked against the air bearing 13. More specifically, the sleeve is dimensioned such that, in the absence of air supply to the air bearing 13, the stem is held firmly by the air bearing 13. However, when air is supplied to the air bearing 13, the sleeve deforms slightly outward to allow movement of the stem, and the air bearing 13 thus actuated reduces or substantially eliminates frictional forces. As a result, the head 5 can be lifted by applying only a very small upward force via the lift cavity 12. When the air supply to the air bearing 13 is removed again, the sleeve contracts and the stem is locked relative to the air bearing and thus to the sleeve.

[0021] In Figure 2A, the head 5 is shown at or near the lower limit of its vertical travel relative to the body 7. A workpiece W supported on a support surface 6 is placed below the reference plate 11. Figure 2B shows the same tower 4 after the head 5 has been raised by supplying air to both the lift cavity 12 and the air bearings 13. The head 5 "floats" upward until the workpiece W contacts the underside of the reference plate 11. At this point, the air supply to the air bearings 13 is removed, locking the head 5 relative to the body 7, and optionally the air supply to the lift cavity may also be removed. As shown in Figure 2C, the reference plate 11 is moved away from the workpiece W, and the head 5 remains in its locked position.

[0022] Rather than using lift springs (as in known systems), a constant upward force is maintained by utilizing lift pressure by supplying air to the lift cavity 12. This eliminates the need to factor in maximum / minimum spring values ​​during design, as well as reducing the maximum force the reference plate must support. Thus, the reference plate 11 can be made significantly thinner and therefore lighter when compared to conventional upper reference plates. As will be explained in more detail below, this improvement allows the use of a common, relatively thin reference plate for both vertical and horizontal referencing operations.

[0023] Moreover, the use of such a flexible body has the added benefit of eliminating the need for high machining tolerances.

[0024] Such towers offer a great deal of freedom in design: for example, the stem can have a square cross section, in which case the air bearing can be flat and continuous with at least two opposite sides of the stem, or alternatively, for example, the stem can have a circular cross section, in which case the air bearing can be annular, completely surrounding the stem.

[0025] 2A-2C , the sleeve may be sized such that in the absence of air supply to air bearing 13 (or alternatively during periods of positive air pressure applied to air bearing 13), a gap is maintained between air bearing 13 and the stem to allow relative movement of air bearing 13 and the stem. Subsequent application of negative pressure to air bearing 13 causes air bearing 13 to buckle, locking the stem relative to air bearing 13.

[0026] In a further alternative embodiment, a separate locking component may be provided, which is actuable upon application of negative pressure.

[0027] Figures 3A-3S show schematic stages in a referencing method according to one embodiment of the present invention. In more detail, Figures 3A-3C show the tooling and reference plate before any referencing is performed, Figures 3D-3J show the vertical referencing operation, Figures 3K-3P show the horizontal referencing operation before the printing operation, and Figures 3Q-3S show the apparatus after the printing operation. For clarity, these figures show only the tooling 2 and reference plate 11, and in particular the lift table supporting the tooling 2, the carrier for feeding the workpiece W into the printer, and the stencil and print head required to perform the printing operation are omitted from these figures.

[0028] 3A-3C show the tooling and the reference plate in side cross-sectional view, plan view and enlarged plan view, respectively, before any referencing is performed. As shown, the tooling 2 comprises eight towers 4 arranged in a 4×2 array, where the support surface 6 of each tower 4 is connected to a respective head 5 via an elastically deformable material (not shown), such as rubber, as previously described. The reference plate 11 is shown in more detail than before, where it can be seen to comprise an upper plate 14 and a lower plate 15 connected by fasteners 16. This allows the upper plate 14 and the lower plate 15 to be held in a parallel horizontal (i.e. lying in the XY plane) configuration, but to be movable relative to each other within this horizontal (XY) plane. More specifically, the lower plate 15 can be moved parallel to a horizontal reference direction HR (shown in FIG. 3B) that is disposed at approximately 45° to the X and Y axes. As is known per se in the art, actuators (not shown) may be provided to move the lower plate 15 in the direction HR and vice versa while the upper plate 14 returns to a stationary state. After the tooling 2 is lifted, an aperture 17 extending through the reference plate 11, i.e. through both the upper plate 14 and the lower plate 15, configured and dimensioned to receive a workpiece W supported on each tower 4 therein, is formed with sufficient clearance to allow for moderate misalignment of the workpiece W on the tower 4. It can thus be seen that as the lower plate 15 is moved in the direction HR, the right and lower edges of the apertures 17 as shown move inwardly of the respective apertures 17, reducing their opening area. These edges thus function as reference surfaces 18, such that when the workpiece W is received within the apertures 17, as these edges move in the direction HR, the reference surfaces 18 contact the workpiece W and urge it towards the upper left corner of the apertures 17 as shown, i.e., towards the horizontal reference position.3C, the reference surface 18 is now made wider in the Z direction by providing an upwardly protruding "L-shaped" wall on the lower plate 15 below and to the right of the aperture 17 that extends into the aperture formed in the upper plate 14. For clarity, in the following description, the term "closed" is used to describe the lower plate 15 moving in the direction HR to reduce the open area of ​​the aperture 17, and the term "opened" is used to describe the lower plate 15 moving in the direction opposite to HR to increase the open area of ​​the aperture 17.

[0029] Optionally, at least one of the upper plate 14 and the lower plate 15 may be flexible or may tolerate small off-axis translational movements in the horizontal plane. This flexibility may be utilized to accommodate small variations in both aperture size and substrate size.

[0030] Figures 3D-3J show various stages of a vertical referencing operation. First, as shown in Figures 3D and 3E, with tooling 2 lowered (and as also shown in Figure 3A), aperture 17 is closed by moving reference surface 18 in direction HR. Note that workpiece W, visible in Figure 3D, is visible through the aperture, but is not received within the aperture.

[0031] The tooling 2 is then elevated by raising a lift table (not shown) closer to the reference plate 11 to a "pre-reference position," as shown in FIG. 3F.

[0032] Next, as shown in Figures 3G-3J, the workpieces W are lifted up to the reference plate 11 by raising the heads 5 of each tower 4 relative to the body 7, i.e., by supplying pneumatic working air to the lifting cavity 12 (see Figure 2). When the workpieces W contact the underside of the reference plate 11, further lifting of the workpieces W is prevented. As shown in Figures 3G and 3H, this lifting may optionally be performed sequentially, with only the leftmost workpiece W being lifted in Figure 3G, while the two leftmost workpieces W are lifted in Figure 3H, until all supported workpieces W are lifted as well. Such sequential lifting may be controlled by suitable control of the air pressure supply to the towers 4, for example using pneumatic logic, serially linked air feeds, or other control means known per se. Sequential lifting may be advantageous to mitigate the maximum upward impulse experienced by the reference plate 11. As shown in Figure 3I, the workpieces W are brought into contact with the underside of the reference plate 11, and more particularly with the underside of the lower plate 15, near the reference surface 18, which closes the aperture 17. This contact serves to reference the workpieces W in the vertical direction. Once all the workpieces W have been referenced in this manner, the locking mechanisms of all the towers 4 are disengaged, for example by removing the air supply to the air bearings 13 (see Figure 2) or by applying a negative pressure to the air bearings 13. The tooling 2 may then be lowered by movement of the lift table, so that the workpieces W are no longer in contact with the reference plate 11, as shown in Figure 3J.

[0033] 3K-3P show the stages of the subsequent horizontal referencing operation before the printing operation. As shown in FIG. 3K, the reference surface 18 is moved to open the apertures 17. Then, as shown in FIGS. 3L and 3M, the tooling 2 is raised towards the reference plate 11 so that the workpiece W approaches the apertures 17 and is then received in these apertures 17. Due to the above mentioned vertical referencing, the workpiece W protrudes upward from the reference plate 11 by the same reproducible distance. Once the workpiece W is fully received in the open apertures 17 (see FIG. 3N), the reference surface 18 moves in the direction HR to close the apertures 17, as shown in FIGS. 3O, 3P. As mentioned before, this serves to refer the workpiece W in the horizontal direction. Once the workpiece W is referenced both vertically and horizontally, it can undergo the printing operation.

[0034] Figures 3Q-3S show the apparatus after the printing operation. After printing, the reference surface 18 moves to open the aperture 17, as shown in Figures 3Q-3R. Finally, as shown in Figure 3S, the tooling 2 may be lowered by movement of the lift table, allowing the printed workpiece W to be returned to the carrier.

[0035] The above described embodiments are merely exemplary, and other possibilities and alternatives falling within the scope of the invention will be apparent to those skilled in the art. For example, as explained above, vertical referencing is performed before horizontal referencing, although this is not strictly necessary if the tower comprises means for locking the support surface in a referenced horizontal position. [Explanation of symbols]

[0036] 1. Printer 2 Touring 3. Climbing table 4. Tower 5 Head 6 Support surface 7. Body 8. Base 9 Air Channels 10 Air pressure supply source 11 Reference Plate 12 Lift cavity 13 Air bearings 14 Upper Plate 15 Lower Plate 16 Fixtures 17 Aperture 18 Reference surface HR horizontal reference direction W work

Claims

1. 1. Tooling for supporting a plurality of singulated workpieces during a printing operation, the tooling comprising a plurality of towers, each tower extending along an axis and configured to support a respective workpiece of the plurality of workpieces in a horizontal orientation, each tower comprising: Body and a head having a support surface provided at a distal end of the head and configured to support each of the workpieces, the support surface being displaceable relative to the body in a plane perpendicular to the axis; Equipped with the body having a pneumatic input for receiving compressed air, the compressed air applying a lifting force to the head to move the head along the axis relative to the body; Each tower includes a locking mechanism for selectively locking the head to the body.

2. 2. The tooling of claim 1, wherein the head comprises an elongated stem extending along the axis, and the body comprises a sleeve having a central aperture dimensioned to slidingly receive the elongated stem therein along the axis.

3. 3. The tooling of claim 2, wherein the locking mechanism comprises an air bearing disposed in the central aperture adjacent to the elongated stem such that when an air supply is supplied to the air bearing, the elongated stem can slide relative to the air bearing parallel to the axis and when the air supply is not supplied to the air bearing, the elongated stem is locked relative to the air bearing.

4. A printer for printing print media onto a plurality of singulated workpieces during a printing operation, the printer comprising the tooling of claim 1 .

5. 5. The printer of claim 4, further comprising a reference plate having a plurality of reference surfaces movable in a horizontal plane, each reference surface being arranged to be movable into contact with one of the singulated workpieces to align the singulated workpieces in the horizontal plane in a horizontal referencing operation.

6. The printer of claim 5 , wherein the reference plate has a lower surface, the lower surface being contactable by the singulated workpiece in a vertical referencing operation.

7. 7. The printer of claim 6, wherein the reference surfaces are movable in the horizontal plane between an open configuration in which the singulated workpieces supported by the respective support surfaces may enter respective apertures formed in the reference plate, and a closed configuration in which the apertures are at least partially closed by the reference surfaces.

8. The printer of claim 7 , wherein the lower surface of the reference plate is contactable by the singulated workpiece in the vertical referencing operation only when the reference surface is in the closed configuration.

9. 1. A method of referencing a plurality of singulated workpieces in a printer prior to performance of a printing operation, the printer comprising: tooling for supporting the singulated workpieces; and a reference plate having a plurality of reference surfaces movable in a horizontal plane, the method comprising: i) supporting the workpiece on the tooling in a horizontal orientation; ii) performing vertical and horizontal referencing operations in any order, the vertical referencing operation includes lifting the supported workpiece into contact with a lower surface of the reference plate and then locking the tooling to hold the supported workpiece at a locked vertical distance from a base of the tooling; the horizontal referencing operation includes lifting the supported workpieces into respective apertures formed in the reference plate and moving the reference surface in the horizontal plane into contact with each supported workpiece; A method comprising:

10. The method of claim 9 , wherein the tooling comprises the tooling of claim 1 .

11. 11. The method of claim 9 or 10, wherein the reference surface is movable in the horizontal plane between an open configuration in which the supported workpiece may enter the respective aperture, and a closed configuration in which the aperture is at least partially closed by the reference surface.

12. The method of claim 11 , wherein the vertical referencing operation includes moving the reference surface into the closed configuration before lifting the supported workpiece into contact with the lower surface of the reference plate.

13. The method of claim 11 , wherein the horizontal referencing operation includes moving the reference surface to the open configuration prior to lifting the supported workpiece into each of the apertures.

14. The method of claim 9 , wherein the vertical referencing operation includes sequentially lifting the supported workpiece into contact with the lower surface of the reference plate.

15. 10. The method of claim 9, including the step of lowering the tooling after the vertical referencing operation to move the supported workpiece away from the reference plate.

Images