Method for calibrating a position of a vacuum pick-up tool

Abstract

This disclosure pertains to a method for calibrating a position of a vacuum pick-up tool relative to a reference position. The method comprises the steps of: providing the carrier having a foil facing the vacuum pick-up tool; contacting the foil with the vacuum pick-up tool at an intended contact position; creating a local suction marking at the intended contact position in the foil by applying a vacuum using the vacuum pick-up tool; disengaging the vacuum of the vacuum pick-up tool and displacing the vacuum pick-up tool away from the intended contact position; imaging, using vision means, the local suction marking to determine an actual position of the local suction marking relative to the intended contact position; and calibrating the position of the vacuum pick-up tool based on the actual position of the local suction marking and the intended contact position.

Description

[0001] TITLE

[0002] Method for calibrating a position of a vacuum pick-up tool.

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to a method for calibrating a position of a vacuum pick-up tool, which is adapted to be used during semiconductor package manufacturing by picking up and subsequently handling of electronic components, such as semiconductor dies, complete chips or semiconductor package, bond clips, capacitors, resistors, inductors, LEDs, or the like, through vacuum control.

[0005] BACKGROUND OF THE DISCLOSURE

[0006] In semiconductor package manufacturing delicate components need to be handled and placed on an assembly to form the semiconductor package, or the electronic component needs to be placed in a tape in case of the final product. The use of a pick-up tool with vacuum openings allows for contacting the delicate electronic components and subsequent application of a vacuum to pick them up to move them to their desired location. At the desired location the vacuum is released, such that the delicate electronic components remain and are thereby placed.

[0007] The vacuum pick-up tool therefore is an essential machine part, since it provides a gentle grip on the electronic component. However for proper functioning, its contact position with the electronic component must be known precisely. Otherwise the vacuum might leak, leading to potential falling of the electronic component during handling, or it might cause the vacuum pick-up tool to pick-up the electronic component at a position far from its center of mass, leading to potential falling of the electronic component as well, or it could place the semiconductor package at an incorrect position on the circuitry. Furthermore, if the pick-up tool position is not accurately aligned with a push needle, used for engaging and disengaging the electronic component, the electronic component may tilt, causing quality and yield issues of the final semiconductor device.

[0008] Therefore, it is indispensable to calibrate the position of the vacuum pick-up tool before use, which is commonly performed by pressing the vacuum pick-up tool into a substrate comprising a layer of foil. The impression of the vacuum pick-up tool leaves a visible imprint on the substrate’s foil, which can be compared against a reference position and the intended position of pressing. For assembling power electronic semiconductor packages or any other assemblies requiring fragile electronic components, this method of calibration however no longer functions. Namely, the vacuum pick-up tools that are used in those applications are made of a softer material in order to become surface conformal with the electronic components and to not damage the electronic component. This causes these types of vacuum pick-up tools to no longer leave visible imprints on the substrate’s foil during calibration, making it impossible to calibrate the vacuum pick-up tool’s position.

[0009] SUMMARY OF THE DISCLOSURE

[0010] Accordingly it is the goal of the present disclosure to provide a method to calibrate the vacuum pick-up tool’s position independent of vacuum pick-up tool material stiffness and size.

[0011] To do so, the disclosure pertains to a method for calibrating a position and / or an orientation of a vacuum pick-up tool relative to a reference position on a carrier or on a machine part of a machine onto which the vacuum pick-up tool is connected. The method comprises the steps of: i) providing the carrier having a foil facing the vacuum pick-up tool; ii) contacting the foil with the vacuum pick-up tool at an intended contact position; iii) creating a local suction marking at the intended contact position in the foil by applying a vacuum using the vacuum pick-up tool; iv) disengaging the vacuum of the vacuum pick-up tool and displacing the vacuum pickup tool away from the intended contact position; v) imaging, using vision means, the local suction marking to determine an actual position and / or an actual orientation of the local suction marking relative to the reference position; vi) calibrating the position and / or the orientation of the vacuum pick-up tool based on the actual position and / or the actual orientation of the local suction marking and the intended contact position, relative to the reference position.

[0012] A method as described above, utilizes a vacuum to exert a negative pressure on the substrate’s foil, instead of a positive pressure as is done in the already known calibration methods. This allows any vacuum pick-up tool, independent of its size and material properties, to leave a local suction marking on the substrate’s foil. Additionally, the calibration for instance can be performed with high resolution, such that the functional of the pick-up tool can be guaranteed to the micrometer level. It may be understood that these vacuum pick-up tools are provided with vacuum channels extending from a central vacuum line opening towards the outer periphery of the vacuum pick-up tool. The material of the vacuum pick-up tool surrounding the vacuum channels is intended to become surface conformal upon vacuum application and the vacuum channels form hollows when the electronic component is picked-up.

[0013] The local making will then be formed along these vacuum channels in the respective hollows. Note that, even if there are no vacuum channels the method according to the disclosure will leave a local suction marking, namely in the shape of the vacuum line opening of the vacuum pick-up tool.

[0014] A vacuum pick-up tool may be understood to be structured to pick-up, hold, and mount an electronic component at a particular position on the carrier or in a carrier tape. However, in order to function this way, the position and / or an orientation of the vacuum pickup tool should be calibrated. Otherwise the risk exists of breaking, letting fall, tilting, or mispositioning an electronic component, because of misalignment with a push needle for (dis)engaging the electronic components from the vacuum pick-up tool’s head, or because of the creation of vacuum leakage.

[0015] In another example of the method, a center point of a field of view of the vision means is used as a reference point during the determination of the actual position of the local suction marking in step v).

[0016] It may be understood that a vacuum pick-up tool is part of an apparatus comprising means for controllably moving the vacuum pick-up tool, which could for instance be achieved with stepper motors attached to encoders and limit switches, but is not limited thereto. Then, when utilizing vision means which are fixed with respect to the field of movement of the moving means, a reference point can be set virtually, removing the need of physical reference points or reference marking on the substrate’s foil.

[0017] For instance, the vision means could set one particular pixel as the intended contact position where the local suction marking should be created. Subsequently, the moving means based on pre-set encoder values would move the vacuum pick-up tool to said intended contact position to create a local suction marking having a local suction marking orientation. After local suction marking creation, the vision means (not having moved) take an image, which can be analyzed to calculate the difference between the pixel set as intended contact position and the pixel(s) showing the actual local suction marking. Furthermore, the pixels indicating an orientation can be used in reference to the image pixel array to obtain an orientation of the local suction marking, and indirectly thus also an orientation of the vacuum pick-up tool. The benefit of taking the center of the vision means as a reference position in the example described above allows to use the flat-field region of the optical vision means, such that no non-linear behavior can be expected during the calibration. It should namely be clear for the person skilled in the art that the optical aberration increase at the edges of the field of view of the vision means, since the outer extremes of the optical elements of the vision means are being used. Another beneficial effect is that this way the vision means can remain fixed with respect to the carrier. Having the vision means not moving, ensures that its imagery can be compared prior and after local suction marking creation and that the vision means’ position is maintained throughout the use of the vacuum pick-up tool.

[0018] It should also be noted that vision means can be understood to be cameras, webcams, video recorders, or the like.

[0019] Furthermore, it is preferable that the calibration of the pick-up tool is performed once at the beginning of the manufacturing process. This way, the pick-up tool can operate continuously and its calibration can be maintained throughout the manufacturing process not being hampered by drift of the individual parts, such as thermal drift, optical drift, etc.

[0020] In an alternative example of the method, a reference feature on the carrier is used as a reference point during the determination of the actual position of the local suction marking in step v).

[0021] Instead of utilizing the center of the field of view of the camera means, a reference feature on the carrier may be used. Such a reference feature could be a reference marking intentionally made on the carrier during fabrication which has no other function than for use in calibration, like a protrusions, indentation, discoloration, etc. Alternatively, a reference feature could also be an edge or a corner feature, obtained by image recognition or edge detection, of an element on the carrier having an intended different function than calibration.

[0022] For instance, the carrier may be provided with alignment slots, which are intended for objects to slot into during later processing of the carrier. However, during calibration they could also serve as reference points to relate the intended contact position to the actual position of the local suction marking.

[0023] As previously mentioned, it is preferred that the calibration method is only performed once at the starting of the manufacturing process. However, when a reference position is taken on carrier, the calibration method may also be performed for every pick-up and placement of an electronic component. For instance, this way small adjustments can be made to the calibration of the pick-up tool to correct drift. The example of the method with a reference position on the carrier (tape) is particularly useful for that, since said reference position is also present and visible during the normal use-process of the pick-up tool. In another example, a reference feature on a machine part to which the vacuum pickup tool is connected is used as a reference point during the determination of the actual position and / or an orientation of the local suction marking in step v).

[0024] For instance, a machine part may be used as reference position since this may act a true solid world. Namely, due to thermal fluctuations in the manufacturing process the pickup tool may drift relative to the camera, or the camera may drift relative to the machine. Therefore, a reference on a true stable point, such as a machine part can be beneficial in that regard. It is this important that this machine part is visible with the vision means and does not block the line of sight with the intended contact position.

[0025] In another example of the method, displacing the vacuum pick-up tool away from the intended contact location in step iv) is performed by displacing the vacuum pick-up tool to a rest position away from the carrier.

[0026] In order to properly execute step v) of imaging the local suction marking, a line of sight has to be created for the vision means to actually image the local suction marking. To guarantee that a line of sight is created a rest position for the vacuum pick-up tool may be used, for instance at an extreme end of the field of movement of the moving means.

[0027] The use of a rest position is beneficial, since next to ensuring a line of sight for the vision means the vacuum pick-up tool, by displacing it to a rest position, is also removed from the area of interest such that in case of malfunctioning of the vacuum pick-up tool after local suction marking creation, the calibration process is not disturbed nor hampered.

[0028] Additionally, the rest position may be used as the location to provide new electronic components to the vacuum pick-up tool.

[0029] The rest position may thus be understood to be a position out of direct sight of the vision means with the local suction marking and such that the vacuum pick-up tool is removed from the area of interest of the calibration process.

[0030] In yet another example of the method, the local suction marking being created in step iii) is a temporary marking due to the viscoelastic or coloration properties of the foil.

[0031] In an alternative example, the local suction marking being created in step iii) is a permanent marking due to the viscoelastic or coloration properties of the foil, or because of a deposition left by the vacuum pick-up tool on the foil.

[0032] As just described in the two examples above, the local suction marking may either be temporary or permanent. The exact behavior depends on the implementation of the method and the type of foil used during the calibration. For instance, one particular foil may be made of a polymeric material, which has viscoelastic properties such that upon deformation the foil would slowly return to its original shape. In said case, the local suction marking would thus be temporary and the vacuum pick-up tool after disengagement of the vacuum has to be moved out of a line of sight of the vision quite rapidly in order to still be able to image the local suction marking.

[0033] Alternatively in another case, a carrier with a discoloring foil may be used, which changes color after the vacuum is applied to create the local suction marking. This discoloration may be permanent, such that there is no rush to displace the vacuum pick-up tool away from the local suction marking. For instance, this could be achieved with pressure sensitive foils that discolor upon the application of pressure, also known as chromogenic polymer foils.

[0034] Therefore, in an example according to the disclosure it is described that the local suction marking that is created in step iii) may be formed due to a deformation or an optical marking of the foil.

[0035] According to another example of the method, the imaging of the local suction marking in step v) may be performed by darkfield, brightfield, differential interference contrast (DIC), phase contrast, or structured illumination imaging.

[0036] These different optical method have different utility based on the type of foil that is being used and thus the type of local suction marking that is being left. For instance, darkfield, and structured illumination imaging may be more effective for visualizing local deformations of the foil, whereas brightfield, DIC, and phase contrast may be more beneficial for observing local discolorations of the foil.

[0037] In yet another example of the method, determining an actual position and / or an orientation of the local suction marking in step v) is performed by template matching, shape recognition, or edge detection, or the like.

[0038] For instance, based on knowledge of the vacuum channel layout on the vacuum pickup tool, a template may be known a-priori which could be used for template matching of the imaged local suction marking to determine the actual position and / or the orientation. During the determination step, its position and / or orientation may be determined to be located at the center of the local suction marking, however it should be noted that it is not limited to determine the actual position of the local suction marking at the center of the template match. Furthermore, the orientation of the local suction marking can be determined with template matching, shape recognition, or edge detection as well. Namely, the orientation with respect to an intended orientation or with respect to the camera orientation can give the user of the method inside about the orientation of the pick-up tool as well.

[0039] In another exemplary case, edge detection could be used to determine the edges of the local suction marking, wherein the edges / contours can be bound by a bounding box. The center of said bounding box may then be taken as the actual position of the local suction marking and the corners may be utilized to determine the local suction marking’s orientation. Yet as another option, the position could also be determined by the location of the highest contrast value obtained from the edge detection in the image. Even further, the actual position could also be determined by a 2D-weighted average based on the contrast values from the edge detection. In the latter case, each pixel can be understood to have an X and Y position, which contribute to a calculated XY-average, wherein a weight is added based on the contrast of the edge detection.

[0040] All in all, the method as described above, allows for vacuum pick-up tool position calibration independent of the pick-up tool’s material properties and size.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figures 1A-D show the method according to the disclosure in 3D.

[0043] Figures 2A-D show side-views of the method according to the disclosure.

[0044] Figures 3A-B show side-views of another implementation of the method according to the disclosure.

[0045] Figures 4A-B show side-views of yet another implementation of the method according to the disclosure.

[0046] Figures 5A-G show various shapes of vacuum channels of a vacuum pick-up tool’s head.

[0047] DETAILED DESCRIPTION OF THE DISCLOSURE

[0048] In the following section, the disclosure is discussed by means of several exemplary figures. In order to aid the understanding of the examples of the disclosure, the same reference numbers are used in the figures, as are used throughout the text. Moreover, these figures should be understood to provide specific examples only to clarify the working principles, they should not be considered to limit the scope of the disclosure.

[0049] Throughout the disclosure the wording “vacuum” is used, but this should be understood to not be absolute vacuum, but rather an under pressure compared to the environment of the vacuum pick-up tool 100. This under pressure of the vacuum pick-up tool 100 should at least be capable of picking-up electronic components at an intended contact position 30 later during use of the device. Furthermore, the under pressure of the vacuum pick-up tool 100 should be at least sufficient to creating a local suction marking 41 on a foil 12 on a carrier 11.

[0050] Please note, that in the following figures the vision means 200 are depicted perpendicularly on top of the carrier 11. However, the vision means 200 do not necessarily have to be perpendicular to the carrier 11. They should at least have a clear line of sight onto the carrier, where the local suction marking 41 will be created and where during later use electronic components will be placed.

[0051] Furthermore, throughout the disclosure the wording “electronic component” is used which should be understood to be a semiconductor die, a complete chip or semiconductor package, a transistor, a capacitor, an inductor, a LED, a lead frame, or another component used in semiconductor manufacturing and / or electronic circuit building.

[0052] Figs. 1A-D show a semi-3D top view and Figs. 2A-D show a side view of the various steps comprised by the method to calibrate a vacuum pick-up tool 100 of the disclosure. In Fig. 1A and Fig. 2A a carrier 11 is provided having a foil 12 facing the vacuum pick-up tool 100. Indicated with the black bold arrow, the vacuum pick-up tool is brought into contact with the foil 12 on the carrier 11 at an intended contact position. Subsequently a (partial) vacuum is applied, as indicated with the three arrows in Fig. 1 B and Fig. 2B, removing air or gas at the vacuum pick-up tool’s head 110 through a suction tube adapted to be connected to vacuum means. Since the vacuum pick-up tool 100 is in contact with the substrate, or even if it were floating slightly above, the carrier 11 with the provided foil 12 would be attracted due to the lower pressure of the applied vacuum compared to the surrounding. This causes the head of the vacuum pick-and-place tool to become surface conformal with the foil 12 on the carrier 11. Only the vacuum channels 115 that are present in the vacuum pick-up tool’s head 110 will not become surface conformal, but these channels will form a hollow with the foil 12 on the carrier 11. Subsequently, due to the presence of the lower pressure and because of the foil’s material properties, the foil 12 may be deformed or colorized along the hollows formed by the vacuum channels 115 on the vacuum pick-up tool’s head. Thereby a local suction marking 41 is created in the same shape as the vacuum channels 115. A few of these shapes will be discussed later in Figs. 5A-G.

[0053] After local suction marking 41 creation, the (partial) vacuum of the vacuum pick-up tool 100 is disengaged and the vacuum pick-up tool is displaced from the intended contact position, as shown in Fig. 1C and Fig. 2C. By moving the vacuum pick-up tool 100 away a line of sight can be created for vision means 200 to image the local suction marking 41 to determine its actual position relative to the reference position 50. This is shown in Fig. 1 D and Fig. 2D. The actual position and / or an orientation of the local suction marking 41 in the image obtained with the vision means 200 can be analyzed through template matching, pattern recognition, edge detection, or the like. Subsequently, the position of the vacuum pick-up tool 100 can be calibrated based on the actual position of the local suction marking 41 and the intended contact position. In Fig. 1 D, template matching, edge detection, or image recognition is used to obtain the actual contact position 40 and / or an orientation of the local suction marking 41. As is shown, the local suction marking 41 has been obtained and a virtual bounding box may be placed around the marking in the image as obtained from the camera. The center of said bounding box may indicate the actual contact position 40 of the vacuum pick-up tool, whereas the crosshairs show the intended contact position. The mismatch between the two can be used to calibrate the vacuum pick-up tool’s position, by either adjusting the encoder settings of the moving means or by physically adjusting the vacuum pick-up tool’s orientation / position with actuators. Furthermore, the corners of the bounding box may be used to obtain an orientation of the local suction marking 41.

[0054] In Fig. 2D, it is shown that a virtual reference position 50 may be used. In said case, a position on the carrier 11 is determined with respect to a fixed position on the camera’s image. For instance, the center of the field of view may be used as said (virtual) reference position 50. Later, in Fig. 4B, it will be shown that this virtual reference position may not be needed in case a physical reference position 50 is used.

[0055] Such a virtual reference position may be used, when the vision means 200 fixed with respect to carrier 11 and when the vacuum pick-up tool 100 can move independently of the visual means’ position. Furthermore, the virtual reference position may be used upon alignment of the pick-and-place apparatus’ controller, driving means 300, and encoders. That way, a pixel position on the image obtained with the vision means 200 can correspond to settings that need to be given to the encoder of the moving means to position the vacuum pick-up tool 100. Then by means of the above-mentioned method of calibration it’s actual position and orientation can be calibrated effectively.

[0056] Furthermore, it is shown in Figs. 2C-D that the local suction marking 41 is created in the foil 12 by means of discoloration. This local suction marking 41 may either be temporary or permanent based on the material properties of the foil 12 that is being used.

[0057] Figs. 3A-B and Figs. 4A-B show side views of two different implementations of a vacuum pick-up tool 100 in pick-and-place apparatuses. The method according to the disclosure is able to be utilized, independently of the exact implementation of the pick-and- place apparatus 1000, in order to calibrate the position and / or orientation of a vacuum pickup tool 100.

[0058] In Fig. 3A, a carousel-like pick-and-place apparatus 1000 is depicted having, eight pick-up tools. The apparatus is, for instance, intended to pick-up electronic components directly opposite to the carrier 11. In order to calibrate the system, a camera is used as vision means, which is fixedly positioned and aimed at the foil 12 on the carrier 11 such that the vacuum pick-up tools are positioned in between the camera and the carrier 11. Then, to calibrate each vacuum pick-up tool, the steps as described in Figs. 1A-D and Figs. 2A-D will be followed. The initial step of providing the carrier 11 with the foil 12 facing the vacuum pick-up tool 100 is shown in Fig. 3A. With use of the camera an intended contact position 30 is chosen for the vacuum pick-up tool 100. Note that this may have happened before the vacuum pick-and-place apparatus 1000 has come into the arrangement as shown in Fig. 3A. Subsequently, the vacuum pick-up tool 100 would contact the foil 12 on the carrier 11 and create a local suction marking, which is not shown in Figs. 3A-B. However, the last few steps are depicted in Fig. 3B, wherein the vacuum is disengaged and the vacuum pick-up tool 100 is displaced from the intended contact position, such that a line of sight is created for the camera with the local suction marking 41 on the foil. The camera can then image the local suction marking 41 to determine its actual position and / or orientation, for instance based on edge detection, template matching, or image recognition to obtain a center point or any other point of interest of the local suction marking 41.

[0059] Thereafter, both the obtained actual position and the original intended contact position 30 are used to calibrate the position of the vacuum pick-up tool 100. This calibration may be understood as adjusting the encoder values or driving means 300 settings slightly, such that the vacuum pick-up tool 100 moves to the correct position, or it may be understood as adjusting some actuators to physically move the vacuum pick-up tool, without any adjustment to the driving means 300 or the settings thereof.

[0060] In case the intended contact position 30 was chosen to be the center of the field of view of the camera, then as shown in Fig. 3B, there is a slight mismatch between the intended contact position 30 and the actual position of the local suction marking 41. This mismatch would then adequately be used to calibrate and adjust the position and / or the orientation of the vacuum pick-up tool 100 in future positioning on the carrier 11. That way, it is ensured that picking-up and positioning electronic components will be done correctly.

[0061] Furthermore, a rest position 310 may be defined as the configuration shown in Fig. 3B, wherein the vacuum pick-up tools are displaced from area of interest and such that a line of sight for the camera is created.

[0062] Lastly, in Fig. 3B the local suction marking 41 is shown to be on top of the foil 12 on the carrier 11. This suggests that the deformation is formed by either deposition or by deformation. With deformation the vacuum of the vacuum pick-up tool 100 would suck in the foil 12 locally along the vacuum channels 115 of the vacuum pick-up tool’s head 110. Such a deformation may thus result in a relief pattern on the foil. Depending on the material properties of the foil, said local suction marking 41 may exist temporarily or permanently. For instance, the viscoelastic properties of a rubber or polymer type foil, would likely result in the creation of a temporal local suction marking 41. In those cases, the vacuum pick-up tool 100 should be displaced rapidly after local suction marking 41 creation in order to properly obtain an image to extract the actual contact location.

[0063] In Figs. 4A-B a pick-and-place apparatus 1000 having linear moving means is shown, having only one vacuum pick-up tool. Here, the linear moving means may extend past the carrier, such that electronic components may be picked-up at the side of the carrier 11.

[0064] Similarly to Fig. 3A-B a camera may be mounted aimed towards the foil 12 on the camera and the vacuum pick-up tool 100 may be movable between the two. Again, similar to the situation shown in Fig. 3A, in Fig. 4A, the camera may have previously been used to pick an intended contact position. Then the moving means are used to position the vacuum pick-up tool 100 at said intended contact position. However this time, the reference position 50 is not taken virtually from a projected position on the camera image, for instance the center of the field of view of the camera, but a physical features in / on the foil 12 on the carrier 11 is be used as the reference position 50.

[0065] In Fig. 4A a reference feature 51 is positioned in the foil 12 on the carrier, of which the position can be identified through imaging with the camera prior to contacting the foil 12 and creating a local mark. The camera may use edge detection, template matching, or image recognition in order to identify the reference feature 51 and find a characteristic position, such as the center point or a maximum of contrast or the like.

[0066] It should also be noted that multiple reference features may be used. Utilizing multiple reference features may aid in correcting for optical aberrations or any other variations.

[0067] Not shown is that the vacuum pick-up tool 100 would contact the foil 12 on the carrier 11 and create a local suction marking 41. But thereafter, when the vacuum is disengaged and the vacuum pick-up tool 100 is displaced from the intended contact position, is shown in Fig. 4B. By moving the vacuum pick-up tool 100 away, a line of sight is created for the camera with the local suction marking 41 on the foil. The camera can then image the local suction marking 41 to determine its actual position with reference to reference feature 51 in / on the foil. Again, the actual contact position and / or orientation of the local suction marking may be determined based on edge detection, template matching, or image recognition.

[0068] With both the actual contact position 40 and the intended contact position 30 known with reference to a reference position, the position of the vacuum pick-up tool 100 can be calibrated effectively. This calibration may be understood as adjusting the encoder values or adjusting driving means 300 settings slightly, such that the vacuum pick-up tool 100 moves to the correct position, or it may be understood as adjusting some actuators to physically move the vacuum pick-up tool, without any adjustment to the driving means 300 or the settings thereof.

[0069] Lastly, Figs. 5A-G show various vacuum pick-up tool 100 heads. As is shown these vacuum pick-up heads may have various shapes of vacuum channels 115. In these images the dark area is intended to contact the foil 12 on the carrier 11 and the white area are channels formed as a recess extending into the vacuum pick-up tool’s head 110. All vacuum pick-up tool 100 heads are provided with at least one vacuum line opening, which is adapted to be connected to vacuum means, such as a turbo pump, scroll pump, screw pump, diaphragm pump or the like. Further, the vacuum pick-up tool 100 may comprise at least one vacuum channel 115, but is not necessitated to have one at all. In case there is no vacuum channel 115, the vacuum pick-up tool 100 will just have at least one vacuum line opening 111 in its head.

[0070] In Fig. 5A, the vacuum pick-up tool 100 comprises two vacuum channels 115 overlapping at their centers and overlapping with the vacuum line opening, thereby forming a cross-like feature. This type of shape is beneficial for picking-up an electronic component, since negative pressure can be generated almost over the entire side of the vacuum pickup tool’s head 110. Furthermore, the shape of the local suction marking 41 left on the carrier’s foil 12 is easily identifiable and its center position can be determined rather easily by finding the center of the cross-like shape.

[0071] In a similar fashion the vacuum pick-up tool’s head 110 of Fig. 5B is formed as a cross-like shape comprising two vacuum channels 115. However, this time the length and the width of the vacuum pick-up tool’s head 110 are not equal creating a rectangular head.

[0072] Another rectangular vacuum pick-up tool’s head 110 is shown comprising twelve vacuum channels 115 oriented overlappingly to create a grid-like pattern, see Fig. 5C. The advantage of the grid-like pattern is that a greater area will experience an under pressure, further facilitating the picking-up of electronic components.

[0073] In Fig. 5D a rectangular vacuum pick-up tool’s head 110 is shown comprising twenty- three vacuum lines. These vacuum channels 115 are formed as circular openings oriented in a rhombic lattice. Note that they may be any type of lattice or array not just limited to rhombic, square, oblique, or random. Note that these vacuum channels 115 may all be connected to the vacuum line opening 111 in the center by an underlying vacuum chamber. Alternatively, the central vacuum line opening 111 splits into small separate lines toward every individual circular vacuum channel 115.

[0074] Then in Fig. 5E, a square vacuum pick-up tool’s head 110 is shown comprising one vacuum channel 115 formed as a circular opening with the vacuum line opening 111 in the middle of the circular opening. In Fig. 5F, a rectangular vacuum pick-up tool’s head 110 is shown comprising four vacuum channels 115 overlapping to form a pattern like in a manual transmission shifter of a car. In other wording, the vacuum channels 115 are oriented such that an H-like feature is obtained with an additional (third) parallel line at the center of the H.

[0075] Lastly, another rectangular vacuum pick-up tool’s head 110 is shown in Fig. 5G comprising three vacuum channels 115 circularly shaped, each having their own individual vacuum line opening 111. This way, each individual vacuum line of the vacuum pick-up tool 100 can be actuated and various sizes of electronic components may be picked-up.

[0076] Throughout all the Figs. 5A-G, the vacuum line opening 111 may be understood to be underlying the to the side the vacuum pick-up tool’s head 110 becoming conformal with the carrier 11. Further, the vacuum channels 115 themselves would form the shape of the local suction marking 41 on the foil.

[0077] It should also be noted that having multiple vacuum channels 115 allows to determine not only a position of the vacuum pick-up tool’s head, but also its orientation in the form of a rotation. Note that this statement assumes round-symmetrical vacuum line openings 111. However, one single asymmetrical vacuum line opening 111 could already suffice to provide information on the orientation of the vacuum pick-up tool 100.

[0078] All in all, the method as described by means on the figures, this disclosure provides a method of calibration the position of a vacuum pick-up tool 100 independent of material properties and size. It also allows to calibrate a vacuum pick-up tool 100 independent of implementation in a vacuum pick-and-place apparatus 1000.

[0079] REFERENCE NUMBERS

[0080] 11 carrier

[0081] 12 foil

[0082] 30 intended contact position

[0083] 40 actual contact position

[0084] 41 local suction marking

[0085] 50 reference position

[0086] 51 reference feature

[0087] 100 pick-up tool

[0088] 110 pick-up tool’s head

[0089] 111 vacuum line opening

[0090] 115 vacuum channel

[0091] 200 vision means

[0092] 210 bounding box

[0093] 300 driving means

[0094] 310 rest position

[0095] 1000 pick-and-place apparatus

Claims

CLAIMS1. A method for calibrating a position and / or an orientation of a vacuum pick-up tool relative to a reference position, the method comprising the steps of: i) providing the carrier having a foil facing the vacuum pick-up tool; ii) contacting the foil with the vacuum pick-up tool at an intended contact position; iii) creating a local suction marking at the intended contact position in the foil by applying a vacuum using the vacuum pick-up tool; iv) disengaging the vacuum of the vacuum pick-up tool and displacing the vacuum pickup tool away from the intended contact position; v) imaging, using vision means, the local suction marking to determine an actual position and / or an actual orientation of the local suction marking relative to the reference position; vi) calibrating the position and / or the orientation of the vacuum pick-up tool based on the actual position and / or the actual orientation of the local suction marking and the intended contact position, relative to the reference position.

2. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to claim 1 , wherein a center point of a field of view of the vision means is used as a reference point during the determination of the actual position and / or an orientation of the local suction marking in step v).

3. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to claim 1 , wherein a reference feature on the carrier is used as a reference point during the determination of the actual position and / or an orientation of the local suction marking in step v).

4. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to claim 1 , wherein a reference feature on a machine part to which the vacuum pick-up tool is connected is used as a reference point during the determination of the actual position and / or an orientation of the local suction marking in step v).

5. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to any of the preceding claims, wherein displacing the vacuum pick-up tool away from the intended contact location in step iv) is performed by displacing the vacuum pickup tool to a rest position away from the carrier.

6. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to any of the preceding claims, wherein the local suction marking being created in step iii) is a temporary marking due to the viscoelastic or coloration properties of the foil.

7. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to any of the claims 1-5, wherein the local suction marking being created in step iii) is a permanent marking due to the viscoelastic or coloration properties of the foil, or because of a deposition left by the vacuum pick-up tool on the foil.

8. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to any of the preceding claims, wherein the local suction marking being created in step iii) is formed due to a deformation or an optical marking of the foil.

9. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to any of the preceding claims, wherein imaging the local suction marking in step v) is performed by darkfield, brightfield, differential interference contrast (DIC), phase contrast, or structured illumination imaging.

10. The method for calibrating a position and / or an orientation of a vacuum pick-up tool according to any of the preceding claims, wherein determining an actual position and / or an orientation of the local suction marking in step v) is performed by template matching, shape recognition, or edge detection.

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