System and method for determining the orientation of a device

Abstract

According to one aspect of the present disclosure, a system for determining the orientation of a device is provided, comprising a diffraction grating deployed on the surface of the device. By irradiating the diffraction grating with a collimating light beam, an m-th order light beam and an n-th order light beam are generated. By monitoring the position on the sensor surface where these light beams are detected, orientation information regarding the orientation of the device can be determined. According to one aspect, the diffraction grating is at least locally flat, perpendicular to a first direction at the center point of the diffraction grating, and the diffraction grating includes repeating pattern units in a second direction from the center point and in the direction opposite to the second direction from the center point, with the pattern units at the center point elongated in a third direction. The collimating light source is configured to emit a collimating light beam toward the center point of the diffraction grating.

Description

[Technical Field]

[0001] Aspects of this disclosure relate to systems and methods for determining the orientation of a device. Aspects of this disclosure further relate to pick-and-place devices comprising such devices. [Background technology]

[0002] A pick-and-place device is a known device that can pick up electronic components from a first carrier and place them on a second carrier. An exemplary application of a pick-and-place device is to pick up a semiconductor die from a semiconductor wafer and place the picked-up semiconductor die on a printed circuit board. In this case, the semiconductor wafer or the carrier supporting it is the first carrier, and the printed circuit board is the second carrier.

[0003] Typically, a pick-and-place device includes a pickup unit for picking up electronic components. This same unit or another unit may be used to place the picked-up electronic components onto a second carrier.

[0004] Known pickup units utilize vacuum force to pick up electronic components. In these units, the electronic component is attracted to a nozzle or tip. To place the electronic component onto a second carrier, the vacuum is removed and / or gas is released through the nozzle or tip, pushing the electronic component away from the pickup unit.

[0005] When deploying electronic components using the pickup unit described above, a problem can arise in the process of deploying multiple electronic components where the force used to deploy the components on the second carrier is not constant. Typically, an adhesive or other material (e.g., solder) is deployed on the second carrier in a predetermined amount to fix and electrically attach the electronic components to the printed circuit board. When the electronic components are pressed into or onto the adhesive, some of the adhesive, which may be at least partially liquid when the electronic components are deployed, may leak out from beneath the electronic components. The amount of leakage, and therefore the amount of adhesive remaining beneath the electronic components, depends, among other things, on the force used to deploy the electronic components on the second carrier. Therefore, if this force is not constant, variations may occur in the amount of adhesive deployed between the electronic components and the second carrier. This results in variations in the height position of the electronic components on the second carrier. In some applications, such as printed circuit boards with LED matrices, this type of variation is undesirable.

[0006] In addition to variations in the height of electronic components, variations can also occur in the orientation of electronic components relative to the second carrier.

[0007] A pickup unit is generally a moving device that is subject to variations in position and orientation. For example, the position in which a pickup unit can place an electronic component may differ slightly from the intended position. Similarly, the orientation in which a pickup unit can place an electronic component may differ slightly from the intended orientation. These variations can also be undesirable. Similar problems can arise when deploying electronic components on a second carrier.

[0008] Determining the orientation and position of a pickup unit is generally complex due to the large number of components within the pick-and-place device. Furthermore, because the pickup unit is in motion during operation, some known techniques for determining the orientation and / or position of the pickup unit cannot be used. [Overview of the Initiative]

[0009] According to an aspect of the present disclosure, a pick-and-place device is provided to address the above problems.

[0010] According to a first aspect of the present disclosure, a system for determining the orientation of a device is provided, and a diffraction grating is disposed on the surface of the device. The system includes a collimated light source configured to emit collimated light onto the diffraction grating to generate an m-th order light beam and an n-th order light beam by diffraction by the diffraction grating, where m is different from n.

[0011] It is known that a diffraction grating can generate different light beams traveling in different directions when irradiated with a beam of collimated light. The angle θ of the incident beam of collimated light with respect to the grating normal m and the angle θ of the m-th order light beam exiting the diffraction grating m For a transmission diffraction grating, the relationship between Equation 1 d(sinθ m - sinθ i ) = mλ where θ i and θ m are both positive when the incident beam and the diffracted beam are on opposite sides of the grating surface normal, m is the diffraction order (…, -2, -1, 0, +1, +2, …), λ is the wavelength of the incident collimated light, d is the characteristic size of the diffraction grating, and must be greater than λ. When the incident beam and the diffracted beam are on the same side of the grating normal, θ m must be considered negative.

[0012] For a reflective diffraction grating, this relationship is Equation 2 d(sinθ m + sinθ i ) = mλ where θ i is positive and θ m is negative when the incident beam and the diffracted beam are on opposite sides of the grating surface normal. When the beams are on the same side of the grating surface normal, both angles are considered positive.

[0013] When the diffraction grating includes multiple regularly arranged slits, d represents the distance from the center of one slit to the center of a directly adjacent slit. In the context of this disclosure, different diffraction orders are referred to using the integer m in Equations 1 and 2 above.

[0014] It should be noted that many different diffraction gratings conforming to the above equations 1 and 2 are known in the art. This disclosure is not limited to any particular form of diffraction grating.

[0015] A system according to a first aspect of the present disclosure further comprises a first photosensor having a first sensor surface. The first photosensor is configured to detect an m-th order light beam. More specifically, the first photosensor is configured to detect a first position on the first sensor surface where the m-th order light beam is detected. Similarly, the system further comprises a second photosensor having a second sensor surface. The second photosensor is configured to detect an n-th order light beam. More specifically, the second photosensor is configured to detect a second position on the second sensor surface where the n-th order light beam is detected, where m is different from n, and both m and n are integers other than zero. Preferably, m = -n, and m is preferably equal to 1.

[0016] The system further includes a processor for determining orientation information regarding the orientation of the device based on the detected first position and the detected second position.

[0017] For this purpose, the diffraction grating is preferably at least locally flat and perpendicular to the first direction at the center point of the diffraction grating. The diffraction grating may also include repeating pattern units in a second direction from the center point and in the direction opposite to the second direction from the center point. The pattern units at the center point can be elongated in a third direction. For example, the pattern unit may be a slit that is elongated in the third direction and has a width d / 2 in the second direction. Elongated stripes or slats with a width d / 4 are arranged on both sides of the slit. By repeating this pattern unit in the second direction and in the direction opposite to the second direction, a regular pattern is obtained in which the distance between the centers of adjacent slits is equal to d.

[0018] A collimating light source can be configured to emit a collimated light beam toward the center point of a diffraction grating. Furthermore, the device may be configured to change its orientation by yawing relative to the yaw axis, tilting relative to the tilt axis, and rolling relative to the roll axis. The orientation information of the device may include the yaw angle, tilt angle, and roll angle. When the device is oriented to a predetermined default orientation, the yaw axis may extend in a third direction, the tilt axis may extend in a second direction, and the roll axis may extend in a first direction.

[0019] The processor may be configured to determine the orientation of a device based on the assumption that a) the center point of the diffraction grating remains in a fixed position in space, b) a predetermined center point of the device remains in a fixed position in space, or c) neither the center point of the diffraction grating nor the center point of the device is fixed in space.

[0020] It may be determined by mechanical constraints which of the assumptions a), b), and c) apply. For example, the movement of the device may be mechanically restricted to any of the above assumptions. Further, in some cases, the determined difference in orientation information between assumptions a) and b) may be small. In such a case, the orientation information can be calculated based on assumption a), even though the actual movement of the device follows assumption b). This can occur, for example, when the center point of the diffraction grating substantially coincides with a predetermined center point of the device. Such a situation can occur when the device is relatively flat in a first direction.

[0021] When the movement of the device follows assumption a), the processor may determine the orientation information based on the detected first position and the detected second position.

[0022] When the movement of the device follows assumption b), the processor may determine the orientation of the device based on the detected first position, the detected second position, and the known positional relationship between the center point of the diffraction grating and a predetermined center point of the device.

[0023] The system may further include a third optical sensor having a third sensor surface, and the third optical sensor is configured to detect the zero-order light beam. More specifically, the third optical sensor can be configured to detect a third position on the third sensor surface where the zero-order light beam is detected.

[0024] When the movement of the device follows assumption c), the processor may determine the orientation of the device based on the detected first position, the detected second position, and the detected third position. In the latter case, the collimated light source should have a known orientation and position with respect to the first, second, and third optical sensors.

[0025] Note that the latter calculation method for determining the orientation and position of the device can be equally used when the movement of the device follows assumption a) or b).

[0026] The processor can be configured to control the orientation of the collimating light source. For example, the device may include a processor-controlled orientation unit for changing the orientation of the light source. Furthermore, the processor may implement a feedback control loop that modifies the orientation of the light source based on the device's determined position and / or orientation to ensure that the collimating light source continues to emit collimated light on the center point of the diffraction grating. This is particularly relevant when the device moves according to assumption b) or c).

[0027] The first sensor, the second sensor, and, where applicable, the third sensor may have fixed, known positions and orientations. Furthermore, the collimating light source may be a coherent light source such as a laser, and the orientation of the coherent light source is known and / or can be determined. The position and orientation information of the light source and / or the first, second, and / or third sensors may be used by the processor when determining the position and orientation of the device.

[0028] The system may further include memory operably coupled to the processor. The memory may include a lookup table containing data that correlates positional data acquired from a first sensor, a second sensor, and optionally a third sensor with the orientation and / or positional information of the device. Using the lookup table can reduce the computational effort and time required to determine the orientation and positional information.

[0029] The first sensor, the second sensor, and optionally the third sensor may be substantially flat sensors. Alternatively, the first sensor, the second sensor, and optionally the third sensor may be curved sensors, such that each point on the corresponding sensor surface is substantially the same distance from a common reference point. The common reference point may substantially coincide with the center point of the diffraction grating, as long as the movement of the device follows assumption a). Furthermore, the first sensor, the second sensor, and optionally the third sensor may be different parts of a single, integrated sensor.

[0030] The diffraction grating can be either a reflective grating or a transmissive grating.

[0031] According to a first aspect of this disclosure, a pick-and-place apparatus is provided for picking an electronic component from a first carrier and placing the component on a second carrier. The apparatus may comprise a pickup unit for picking the electronic component and a pickup unit for placing the electronic component. The pickup unit for picking the electronic component may be the same as the pickup unit for placing the electronic component. The apparatus may further comprise the above system in which a diffraction grating is provided on the pickup unit.

[0032] A first aspect of the present disclosure provides a method for determining the orientation of a device, wherein the surface of the device is provided with a diffraction grating. The method includes: i) emitting collimated light onto the diffraction grating to generate an m-order light beam and an n-order light beam by diffraction by the diffraction grating, where m is different from n and m and n are both integers other than zero; ii) detecting the m-order light beam using a first photosensor having a first sensor surface, wherein the detection step includes detecting a first position on the first sensor surface where the m-order light beam is detected; iii) detecting the n-order light beam using a second photosensor having a second sensor surface, wherein the detection step includes detecting a second position on the second sensor surface where the n-order light beam is detected; and iv) determining the orientation of the device based on the detected first position and the detected second position using a processor.

[0033] A second aspect of the present disclosure provides a pick-and-place apparatus for picking an electronic component from a first carrier and placing the electronic component on a second carrier. The apparatus comprises a pickup unit for picking the electronic component and a pickup unit for placing the electronic component, the pickup unit being the same pickup unit used for picking the electronic component. The outer surface of the pickup unit is provided with a diffraction grating having a repeating pattern unit in a first direction. The apparatus further comprises at least one collimating light source configured to emit collimating light onto the diffraction grating when picking an electronic component from the first carrier and / or placing the electronic component on the second carrier. The system further comprises a sensor system for sensing an nth-order light beam from the diffraction grating, wherein |n|>0, and a processor configured to determine a change in the length of the pickup unit in a first direction at the position of the diffraction grating based on the sensed nth-order light beam when picking an electronic component from the first carrier and / or placing the electronic component on the second carrier.

[0034] In short, according to the second embodiment, the nth-order optical shift is used to detect changes in the length of the pickup unit in a direction perpendicular to the diffraction grating. For example, when a pickup unit is pressed against a semiconductor die during the process of picking a semiconductor die, the pickup unit deforms slightly. More specifically, the length may decrease in a first direction perpendicular to the surface of the semiconductor die, and increase in a second direction perpendicular to this first direction. By positioning the diffraction grating perpendicular to either the first or second direction, it becomes possible to determine the corresponding change in length by inspecting the nth-order optical beam. This is reflected in equations 1 and 2, which show that the diffraction angle changes when the distance d changes due to the change in length.

[0035] It should be noted that by inspecting the nth-order light beam, the length change at the position of the diffraction grating can be determined. The length change does not need to be uniformly distributed throughout the entire pickup unit, nor does the force acting on the pickup unit cause a change restricted to a particular direction. Generally, if the correlation between the cause of the length change and the length change itself is known, for example by having a physical model of the pickup unit, it may be possible to determine the cause, i.e., force or strain, by monitoring the nth-order light beam.

[0036] The processor may be further configured to determine, based on a determined change in length, a first force acting on the electronic component and / or the first carrier by the pickup unit when picking the electronic component from the first carrier, and / or a second force acting on the electronic component and / or the second carrier by the pickup unit when placing the electronic component on the second carrier. The force acting on the electronic component or the first carrier by the pickup unit is generally the inverse of the reaction force acting on the pickup unit by these components. A similar consideration applies to the second force.

[0037] A physical model of the pickup unit may be used to determine the first and second forces. Such a model can, for example, explain how the pickup unit deforms as a result of forces acting on its outer surface. Such a physical model may be tensor-based.

[0038] The device may further include a movable support unit, such as a robotic arm, on which a pickup unit is mounted. In this case, the processor may be configured to adjust the force acting on the electronic component and / or the first carrier by the movable support unit via the pickup unit when picking an electronic component from the first carrier, and / or when placing an electronic component on the second carrier, by the movable support unit via the pickup unit. For this purpose, the processor can directly control the movable support unit. Alternatively or additionally, the processor can control the support unit on which the first or second carrier is placed. For example, by moving the support unit relative to the movable support unit, it becomes possible to adjust the force acting during component picking and / or placement.

[0039] The processor may be configured to determine a first force and / or associated length change during the picking of an electronic component, compare the determined first force and / or associated length change with a first reference change of the first reference force and / or associated length, and generate a first comparison result. Additionally or alternatively, the processor may be configured to determine a second force and / or associated length change during the placement of an electronic component, compare the determined second force and / or associated length change with a second reference change of the second reference force and / or associated length, and generate a second comparison result.

[0040] The first and second comparison results can be used in a manual or automatic feedback control loop. In an automatic feedback control loop, the processor can be configured to adjust, depending on the first and / or second comparison results, the force acting on the electronic component and / or the first carrier by the movable support unit via the pickup unit when picking the electronic component from the first carrier, and / or the force acting on the electronic component and / or the second carrier by the movable support unit via the pickup unit when placing the electronic component on the second carrier.

[0041] In a manual feedback control loop, the processor can be configured to output signals to the user corresponding to the first and / or second comparison results. In this case, the processor can be configured to receive user input to adjust the force acting on the electronic component and / or the first carrier by the movable support unit via the pickup unit when picking the electronic component from the first carrier, and / or when placing the electronic component on the second carrier by the movable support unit via the pickup unit.

[0042] The pick-and-place device may be operably coupled to a processor and further include a memory holding a lookup table that correlates changes in the length of the pickup unit in a first direction at the position of the diffraction grating to values ​​of force and / or strain acting on the pickup unit related to the length contraction. By using the lookup table, the computational strain or time required to determine the values ​​of force and / or strain acting on the pickup unit related to the length contraction is reduced.

[0043] The sensor system may be further configured to sense an m-th order light beam from a diffraction grating, where m is different from 0 and n. In this case, the processor may be configured to determine a change in the length of the pickup unit in the first direction at the position of the diffraction grating, based on the sensed n-th order light beam and the sensed m-th order light beam, when picking an electronic component from a first carrier and / or placing an electronic component on a second carrier. Preferably, m is equal to -n, and n is preferably equal to 1.

[0044] The processor may be configured to determine the orientation of the pickup unit when picking an electronic component from a first carrier and / or placing an electronic component on a second carrier, based on a sensed nth-order light beam and a sensed mth-order light beam. This determination may be performed as described in relation to a first aspect of the present disclosure.

[0045] If the orientation of the pickup unit is fixed, simply monitoring a single high-order light beam from the diffraction grating may be sufficient to determine the length change, provided that this light beam is not a zero-order light beam.

[0046] In some cases, the orientation of the pickup unit may change, for example, as a result of physical contact between the pickup unit and an electronic component, a first carrier, or a second carrier. In these cases, the orientation can be determined using a system according to a first aspect of the present disclosure.

[0047] For example, if the sensor system comprises a first sensor and a second sensor of a system according to a first aspect of the present disclosure, the orientation of the pickup unit can be determined regardless of the exact value of d, provided that the movement of the pickup unit conforms to assumption a) above. The value of d can then be determined using the detected first and second positions, thereby making it possible to calculate the first force or the second force. The determined orientation may also be taken into account in this calculation. For example, the fact that the pickup unit has changed orientation may mean that the force acting by the pickup unit on the electronic component, the first carrier, or the second carrier may be different from the force acting when the orientation has not changed.

[0048] The sensor system can be configured to sense a zero-order light beam from a diffraction grating. In this case, the processor can be configured to determine the change in the length of the pickup unit in the first direction at the position of the diffraction grating, based on the sensed zero-order light beam, the sensed n-order light beam, and the sensed m-order light beam, when picking an electronic component from a first carrier and / or placing an electronic component on a second carrier. Furthermore, the processor can be further configured to determine the orientation and position of the pickup unit, based on the sensed zero-order light beam, the sensed n-order light beam, and the sensed m-order light beam, when picking an electronic component from a first carrier and / or placing an electronic component on a second carrier. The calculation of the position and orientation of the pickup unit can be performed using a system according to a first aspect of this disclosure.

[0049] The pick-and-place device may further comprise at least one orientation unit for changing the orientation of at least one collimating light source, and the processor is configured to control at least one orientation unit in accordance with a determined orientation and / or position in order to ensure that light from at least one collimating light source collides with a diffraction grating during the picking of each of a plurality of electronic components to be picked from a first carrier, and / or that light from at least one collimating light source collides with a diffraction grating during the placement of each of a plurality of electronic components to be placed on a second carrier.

[0050] The first carrier can be a semiconductor wafer or a carrier supporting a semiconductor wafer, in which case the electronic component placed and deployed is a semiconductor die from the semiconductor wafer. Furthermore, the second carrier can be a printed circuit board. Alternatively, the electronic component can be a packaged semiconductor die or device.

[0051] The diffraction grating can be either a transmission type or a transparent type.

[0052] At least one collimating light source may include a first collimating light source configured to emit collimating light onto a diffraction grating when an electronic component is picked from a first carrier, and a second collimating light source configured to emit collimating light onto a diffraction grating when an electronic component is placed on a second carrier. In this case, the sensor system may include a first sensor subsystem for sensing the light beam from the diffraction grating when an electronic component is picked from the first carrier, and a second sensor subsystem for sensing the light beam from the diffraction grating when an electronic component is placed on a second carrier. The sensor system, i.e., the first sensor subsystem and the second sensor subsystem, may each include a sensor for sensing the 0th, mth, and nth order light beams from the diffraction grating, respectively.

[0053] A second aspect of the present disclosure provides a method for picking an electronic component from a first carrier. The method includes: i) using a pickup unit to pick an electronic component from a first carrier, wherein the outer surface of the pickup unit is provided with a diffraction grating having repeating pattern units in a first direction; ii) emitting collimating light onto the diffraction grating when picking the electronic component from the first carrier; iii) sensing an nth-order light beam from the diffraction grating, where |n| > 0; and iv) determining a change in the length of the pickup unit in the first direction at the position of the diffraction grating based on the sensed nth-order light beam when picking the electronic component from the first carrier.

[0054] A second aspect of the present disclosure provides a method for positioning an electronic component from a second carrier. The method includes: i) positioning an electronic component from a second carrier using a pickup unit, wherein the outer surface of the pickup unit is provided with a diffraction grating including repeating pattern units in a first direction; ii) emitting collimating light onto the diffraction grating when positioning the electronic component on the second carrier; iii) sensing an nth-order light beam from the diffraction grating, where |n| > 0; and iv) determining, based on the sensed nth-order light, a change in the length of the pickup unit in the first direction at the position of the diffraction grating when positioning the electronic component on the second carrier.

[0055] A third aspect of the present disclosure provides a pickup unit for a pick-and-place apparatus, the pickup unit comprising a deformable shaft having an outer surface that is elongated along its longitudinal axis and includes a flat portion. The pickup unit further comprises at least one diffraction grating formed on or disposed on the flat portion of the outer surface. The pickup unit can be used in a pick-and-place apparatus according to a second aspect of the present invention.

[0056] The shaft is deformable such that the forces acting on the shaft during the operation of the pick-and-place device cause deformation which can be determined by the pick-and-place device according to a second aspect of the present invention. For this purpose, the deformable shaft can be made from one or more polymers.

[0057] The deformable shaft may be a hollow deformable shaft defining a central bore. Furthermore, the pickup unit may further include a hollow tip portion fixedly connected to the end of the hollow deformable shaft. The hollow tip portion may have a central bore aligned with the central bore of the hollow deformable shaft, thereby forming a continuous central bore. The hollow tip portion may be made of a different material from the deformable shaft. In other embodiments, the hollow tip portion is integrally connected to the deformable shaft.

[0058] At least one diffraction grating may include a repeating of a first pattern unit in a first direction. This first direction may be perpendicular or parallel to the longitudinal axis. It should also be noted that this disclosure does not exclude other orientations of the diffraction grating with respect to the longitudinal axis, for example, it may be positioned at an angle of 40 to 50 degrees, preferably 45 degrees, with respect to the longitudinal axis.

[0059] At least one diffraction grating may include a repeating second pattern unit in a second direction, the second direction may be perpendicular to the first direction. Typically, when multiple diffraction gratings are used, each diffraction grating is supplied with its own incident light beam from a collimating light source. As described in relation to the first and second aspects of this disclosure, each diffraction grating may be used separately to determine force, orientation, or position, but components such as sensors may be shared. For example, the force acting on the pickup unit, the orientation of the pickup unit, and / or the position of the pickup unit may be determined as described above using only the first diffraction grating, or the force acting on the pickup unit, the orientation of the pickup unit, and / or the position of the pickup unit may be determined as described above using only the second diffraction grating. By combining these results, more refined values ​​may be obtained for the force acting on the pickup unit, the orientation of the pickup unit, and / or the position of the pickup unit.

[0060] A third aspect of the present disclosure provides a method for manufacturing the pickup unit. The method includes the steps of: providing a mold having an inner wall defining a mold cavity; providing a diffraction unit having a body having an outer surface on which a diffraction grating is provided; and positioning the diffraction unit in the mold cavity with its diffraction grating in contact with the inner wall. Next, a molding material is cast in the mold cavity, and the cast molding material is at least partially cured to form a solidified molding material body which is fixedly attached to the diffraction unit. In the final step, the body and the diffraction unit are removed from the mold. Further curing or processing steps may be performed on the body and the diffraction unit to form a pickup unit.

[0061] The method may further include the step of positioning a shaft within the mold cavity, preferably spaced apart from the diffraction unit, in order to form a central bore during a subsequent molding process.

[0062] A third aspect of the present disclosure provides a pick-and-place device for picking an electronic component from a first carrier and placing the electronic component on a second carrier. The device comprises the pickup unit described above, at least one collimating light source configured to emit collimating light onto a diffraction grating when picking an electronic component from the first carrier and / or placing an electronic component on the second carrier, a sensor system for sensing an nth-order light beam from the diffraction grating, wherein |n| > 0, and a processor configured to determine a change in the length of the pickup unit in a first direction at the position of the diffraction grating based on the sensed nth-order light beam when picking an electronic component from the first carrier and / or placing an electronic component on the second carrier.

[0063] The pickup unit may have a central bore as described above. In this case, the device may further include a pressure regulating unit connected to the central bore of the pickup unit. The processor can be configured to control the pressure regulating unit to lower the pressure in the central bore to pick up electronic components using suction and to raise the pressure in the central bore to position the electronic components. [Brief explanation of the drawing]

[0064] To enable a more detailed understanding of the features of this disclosure, a more specific description is given with reference to embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings show only typical embodiments and should therefore not be considered limiting to the scope. The drawings are for the purpose of facilitating the understanding of this disclosure and are therefore not necessarily drawn to scale. The advantages of the claimed subject matter will become apparent to those skilled in the art by reading this specification in conjunction with the accompanying drawings, and similar reference numerals are used in the accompanying drawings to indicate similar elements.

[0065] [Figure 1] The image shows a transmission-type diffraction grating (top) and a reflection-type diffraction grating (bottom). [Figure 2] A schematic diagram of a pick-and-place device in accordance with this disclosure is shown below. [Figure 3] An embodiment of a pick-and-place device according to this disclosure is shown. [Figure 4A] Figure 3 shows different detailed views of the apparatus. [Figure 4B] Figure 3 shows different detailed views of the apparatus. [Figure 4C] Figure 3 shows different detailed views of the apparatus. [Figure 4D] Figure 3 shows different detailed views of the apparatus. [Figure 5] Figure 3 shows the mold used to manufacture the pickup unit of the device. [Figure 6] Figure 2 shows the various rotations determined by the system. [Figure 7]A method for detecting the angle of a light beam is shown according to one aspect of this disclosure. [Modes for carrying out the invention]

[0066] Figure 1 shows the diffraction grating patterns for transmission (top) and reflection (bottom). In both cases, the collimated light beam 3 is at an angle θ with respect to the normal 2. i The light is then incident on the diffraction grating 1. Through diffraction, a higher-order light beam 5 is generated in addition to the 0th-order light beam 4.

[0067] Figure 1 shows two higher-order light beams, i.e., 2 and θ relative to the normal. m =θ 1,+1 and θ m =θ 1,-1 Two primary light beams forming an angle are shown. Both angles conform to Equation 1, and for transmission and reflection diffraction gratings,

number

[0068] When the distance d changes, the angle θ 1,+1 and θ 1,-1 It can be seen that this also changes. Furthermore, when the diffraction grating changes orientation, the light beams corresponding to the +1st and -1st orders change the paths they take as they propagate through space. According to one aspect of this disclosure, by deploying a diffraction grating in a device, it becomes possible to monitor changes in the orientation and length of the device. The applicant has recognized that this particular monitoring method is particularly effective in pick-and-place devices that pick and place electronic components with high precision. Furthermore, such non-contact measurement techniques are particularly useful when inspecting pickup units.

[0069] Figure 2 schematically shows a pick-and-place device 100 according to this disclosure. The device described above may correspond, for example, to a pickup unit of this pick-and-place device.

[0070] The apparatus 100 comprises a pickup unit 110, the outer surface of which a first diffraction grating 111 and a second diffraction grating 112 are provided. Each pattern 111, 112 includes a repetition of its respective pattern unit. The pattern units of the diffraction gratings 111, 112 may be different from each other. For example, the characteristic distance d and / or the configuration of the diffraction gratings 111, 112 may be different. Furthermore, the direction in which the pattern units are repeatedly arranged may be different for each pattern 111, 112.

[0071] The apparatus 100 further comprises a first collimating light source 121 and a second collimating light source 122, and their orientation may be changed using the respective orientation units 131 and 132.

[0072] The device 100 includes sensor systems 141 and 142, respectively, for sensing the light beams from the diffraction gratings 111 and 112. Each sensor system 141 and 142 includes three sensors 143, one for sensing the 0th order, one for sensing the +1st order, and one for sensing the -1st order.

[0073] The device 100 includes a processor 150 configured to process signals from sensor systems 141 and 142. The processor 150 controls a movable support unit 160 on which a pickup unit 110 is mounted.

[0074] The processor 150, together with the collimating light sources 121, 122 and the sensor systems 141, 142, may form a system for determining the orientation of the pickup unit 110, as described below. Furthermore, more light source sensor systems may be provided to determine changes in the orientation, position, and / or length of the pickup unit 110 at various locations within the apparatus 100, for example, at the location where an electronic component is picked up from the first carrier or at the location where an electronic component is placed on the second carrier. In addition, embodiments using fewer or more diffraction gratings on the surface of the pickup unit 110 are also possible.

[0075] Figure 3 shows an embodiment of a pick-and-place apparatus 200 according to the present disclosure. It comprises a carousel 201 on which four pickup units 110 are mounted. Also shown is a semiconductor wafer 300 comprising a plurality of semiconductor dies 301 deployed on a second carrier 302. The semiconductor wafer 300 is deployed on a film or foil and further supported by a stage (not shown) that is movable in the z, y directions as shown in Figure 3. In this case, the film or foil, or a film frame carrier to which the film or foil is attached, acts as the first carrier. Similarly, the second carrier 302 is supported by a stage (not shown) that is movable in the x, y directions as shown in Figure 3. A suitable electric motor can be used to move the aforementioned stage.

[0076] Next, we will explain the process of picking and positioning the semiconductor die 301.

[0077] To pick up a semiconductor die 301 from wafer 300, the stage supporting the semiconductor wafer 300 is moved to align the next semiconductor die on wafer 300 with the pickup unit 210_1.

[0078] To pick up the semiconductor die 301, the pickup unit 210 and the wafer 300 are moved toward each other. This can be achieved, for example, by moving the pickup unit 210 in the opposite direction to the x-direction using the movable support unit 160 shown in Figure 2, and / or by moving the stage supporting the semiconductor wafer 300 in the x-direction.

[0079] The needle-shaped element 303 is provided on the back surface of the semiconductor wafer 300. This element can be moved in the x-direction, and by punching or pressing it into the foil, the semiconductor die 301 at this position is at least partially separated from the rest of the wafer 300.

[0080] The pickup unit 210 is provided with a tip through which an attractive force can be applied. This attractive force causes the semiconductor die 301 to attach to the tip of the pickup unit 210. Next, the carousel 201 is rotated clockwise to align the last picked-up semiconductor die 301 with the second carrier 302. Typically, the second carrier 302 is provided with discrete spots of adhesive such as solder. Using a stage that supports the second carrier 302, the second carrier 302 is moved to align the empty position on the second carrier 302 with the pickup unit 210. Once the alignment is complete, the pickup unit 210 and the second carrier 302 are moved toward each other in the z direction. Again, this movement can be achieved by moving the pickup unit 210 and / or the second carrier 302. When the pickup unit 210 is sufficiently close to the second carrier 302, the attractive force at the tip of the pickup unit 210 is removed and / or pressure is applied to the tip to push the semiconductor die 301 away from the pickup unit. Note that even while a semiconductor die is being deployed on the second carrier 302, a new semiconductor die can be picked up from the semiconductor wafer 300. This is made possible by deploying multiple pickup units 210 on the carousel 201.

[0081] During the pick-and-place process, the pickup unit 210 may physically contact the semiconductor die 301. For example, the pickup unit 210 may contact the semiconductor die before picking it. In this case, the semiconductor die is positioned between the pickup unit 210 on one side and the foil and needle-shaped element 303 on the other side. Similarly, while positioning the semiconductor die 301, the pickup unit 210 may press the semiconductor die 301 against the second carrier 302.

[0082] To enable a uniform pick-and-place process, the force exerted by the pickup unit 210 on the semiconductor die 301 is ideally constant throughout the process and between wafers. Similarly, the orientation of the pickup unit 210 is preferably constant and / or known. For this purpose, the pick-and-place apparatus 200 may be provided with a system for determining the orientation of the pickup unit 210. This system uses a diffraction grating 211 positioned on the outer surface of the pickup unit 210. A collimated light source, comprising a light source 221 and a collimating lens 221A, generates a collimated light beam that collides perpendicularly with the diffraction grating 211. The +1st and -1st order light generated by the diffraction grating 211 is sensed using optical sensors 241 and 242, each having a sensor surface 241A. More specifically, the optical sensors output coordinates on the sensor surface 241A where the light beam is detected.

[0083] In Figure 3, the pick-and-place device 200 comprises a single carousel 201. As a result, the semiconductor dies 301 are picked up and placed from the same side using the same pickup unit. In some applications, the orientation of the semiconductor 301 should be reversed between picking and placing the semiconductor die 301. An example is the flip-chip application.

[0084] Reversing the orientation of the semiconductor die 301 can be achieved using a second carousel positioned next to carousel 201. The second carousel then receives the semiconductor die 301 from carousel 201. More specifically, the pickup unit on the second carousel is similar to the pickup unit on carousel 201 and receives the semiconductor die 301 from carousel 201. The pickup unit on the second carousel then performs the final placement of the semiconductor die 301 onto the second carrier 302.

[0085] A processor like the one shown in Figure 2, processor 150, is used to collect data from sensors 241 and 242 and to determine the change in length at the point where the collimated light beam strikes the diffraction grating 211. This is shown in more detail in Figures 4A to 4D.

[0086] As shown in Figure 4B, the pickup unit 210 is pushed toward the pickup unit 201 by, for example, the needle-shaped element 303, and thus comes into contact with the semiconductor die 301. The force exerted on the pickup unit 210 causes it to deform.

[0087] The pickup unit 210 is shown in detail in Figures 4C and 4D. The pickup unit 210 comprises a deformable shaft 2101 having a central bore 2102. The outer surface 2103 of the pickup unit 210 has a flat portion 2104 on which a diffraction grating 211 is provided. This pattern comprises multiple pattern units that are elongated in the x-direction and repeated in the y-direction. Note that Figure 4C shows the elongated shaft 2101 and diffraction grating 211 in a deformed state.

[0088] The pickup unit 210 further comprises a tip section 2105 having a central bore 2106. The tip section 2105 is typically fastened or attached to the shaft 2101 so that the central bore 2102 and the central bore 2106 are aligned. By reducing the pressure in the central bore 2101, an attractive force can be generated at the end of the tip section 2105. Similarly, by increasing the pressure in the central bore 2102, the semiconductor die 301 can be pushed away from the tip section 2105.

[0089] The tip 2105 can be attached to the shaft 2101 using several different techniques. For example, an intermediate fit or an adhesive such as glue may be used. Alternatively, the shaft 2101 and the tip 2105 can be formed integrally.

[0090] Figure 4D shows the shaft 2101 when no external force is applied to the pickup unit 210, and Figure 4C shows the shaft 2101 when an external force in the x direction is applied to the pickup unit 210. As a result of this force, the shaft 2101 deforms in the x and y directions. More specifically, the length of the shaft 2101 in the x direction decreases, and the width of the shaft 2101 in the y direction increases.

[0091] In Figures 4C and 4D, the diffraction grating 211 is arranged such that its elongated pattern units have their longitudinal axes aligned along the x-direction. As a result of the deformation in the y-direction, the effective value of the distance d in Equations 3 and 4 changes and becomes larger. This causes the +1st and -1st order light beams to separate from each other. This change can be detected by sensors 241 and 242. More specifically, using position data from sensors 241 and 242, the processor can determine the deformation at the position within the diffraction grating 211 where the collimated light beam collides with the diffraction grating 211. Using a physical model of the pickup unit 210, this deformation can be used to calculate the force acting on the tip 2105. This force is related to the reaction force acting on the semiconductor die 301.

[0092] The diffraction grating 211 is shown as an elongated pattern unit in the x-direction, but an elongated pattern unit in the y-direction can also be used similarly. However, in such a deployment, higher-order light beams are generated in the xz plane. In pick-and-place devices, generally, there is more space available to deploy the required light sources and sensors in the xz plane than there is available space to deploy them in the zy plane.

[0093] After establishing the deformation in the pickup unit 210 and / or the force acting on the pickup unit 210, the processor may control the drive used to bring the pickup unit 210 into physical contact with the semiconductor 301. For example, when the pickup unit 210 is driven by a movable support unit 160, such as the one shown in Figure 2, which may be in the form of a linear motor, the processor may control this unit to increase or decrease the force acting on the pickup unit 210. This adjustment may be made while picking the semiconductor die 301, or the adjustment may be made with respect to the semiconductor die 301 to be picked up next. In this way, the force acting on the semiconductor die 301 during picking can be uniformly controlled.

[0094] While the process has been described in relation to picking the semiconductor die 301, a similar approach can also be used when placing the semiconductor die 301 on a second carrier 302. This generally requires the use of a separate collimating light source and a separate sensor. Since the component is preferably placed in the zy-plane, the photosensor is preferably positioned to emit a collimating light beam onto the diffraction grating 211 in the x-direction. A sensor for detecting the resulting higher-order diffraction beam is then positioned next to the photosensor in the y-direction and the opposite direction to the y-direction. In Figure 3, the positions of the light source and photosensor for monitoring during component placement are indicated using a circle and a pair of triangles, respectively.

[0095] In the pick-and-place devices described in relation to Figures 3 and 4A-4D, a movable support unit for moving the pickup unit 210 in one direction has been described. This disclosure is not limited to such a movable support unit. In other embodiments, a robotic arm is used on which the pickup unit is mounted.

[0096] Figure 5 shows a mold 400 for manufacturing a pickup unit 210. The mold 400 comprises a retaining box 401 in which several mold parts 402A to 402C can be arranged. For this purpose, the retaining box 401 may also comprise a sealing door 403 which can be secured to the rest of the retaining box 401 using sealing screws 404. By opening the sealing door 403, the mold parts 402 and at least the partially solidified pickup unit 210 can be removed from the retaining box 401.

[0097] Typically, mold parts 402A and 402B are mirror images of each other. Furthermore, mold parts 402A and 402C are copies of each other. Note that Figure 5 does not show a mold part that is complementary to mold part 402C.

[0098] The inner walls of mold parts 402A, 402B, and 402C define the outer surface of the pickup unit 210. These walls also define the mold cavity 405. Inside the mold cavity 405 is a diffraction unit 406, which consists of a body having an outer surface on which a diffraction grating 211 is provided. The diffraction unit 406 is positioned inside the mold cavity 405 such that the diffraction grating 211 faces the inner walls of mold parts 402A, 402B, and 402C.

[0099] The shaft 407 is positioned within the mold cavity and is configured to create a central bore 2102. Furthermore, on the upper surface, mold parts 402A, 402B, and 402C come together to form a pair of injection cups 408. After closing the retaining box 401, the liquid molding material is injected into the injection cups. Gas in the mold cavity can escape through the gas vent channel 409. The molding material may include, for example, one or more resins and / or polymers.

[0100] Once at least partially solidified, the retaining box 401 can be opened and the mold parts 402A-402C, the shaft 406, and the pickup unit 210 can be removed. Optionally, additional processing can be performed on the pickup unit 210 to further harden it.

[0101] By using the method described above, a pickup unit 210 is obtained, in which the diffraction grating 211 is fixedly mounted on the deformable shaft 210. Other options exist in which the diffraction grating 211 may be formed on or inside the deformable shaft 210. For example, a pattern corresponding to the inversion of the diffraction grating can be formed on the inner wall of mold parts 402A-402C. In this case, the diffraction grating is formed during the molding process. Other imprint techniques are also possible in which the diffraction grating is press-fitted onto the deformable shaft.

[0102] Up to this point, we have assumed that the pickup unit 210 has a constant orientation during part picking and part placement. Under these conditions, a single higher-order diffraction beam can be measured to determine the force or strain acting on the pickup unit 210. However, this assumption is not always true, especially since the pickup unit 210 may be configured as a moving unit. Due to mechanical tolerances and clearances, the pickup unit 210 may exhibit yaw, tilt, and roll, as described in relation to Figure 6. This figure assumes a diffraction grating consisting of pattern units that are long in the z direction and repeated in the x direction. In Figure 6, yaw is defined as rotation around the z axis, tilt as rotation around the x axis, and roll as rotation around the y axis.

[0103] Figure 6 further shows the center point C1 of the diffraction grating and the center point C2 of the entire pickup unit 210. Note that Figure 7 shows a cross-sectional view of the pickup unit 210, where the cross-section in the zy-plane is shown midway along the pickup unit 210 in the x-direction.

[0104] Here, a method for determining the orientation of the pickup unit 210 is described based on three possible assumptions regarding the movement of the pickup unit 210.

[0105] In the first case, it is assumed that the orientation of the pickup unit 210 can change due to yaw, roll, and tilt relative to a center point C1 fixed in space. In this case, the collimating light source emits a collimated light beam at the center point C1. The higher-order light beam generated by diffraction is then captured using sensors. More specifically, in this case, two sensors are sufficient to uniquely determine the orientation of the pickup unit 210. The orientation can correspond to the yaw angle, tilt angle, and roll angle.

[0106] When using two sensors, the position data obtained from these sensors includes four independent parameters (e.g., x1, x2, y1, y2), where xn and yn represent the positions on the sensor surface where sensor n detects the higher-order diffraction beam. The orientation of the pickup unit 210 includes three degrees of freedom: yaw angle, tilt angle, and roll angle.

[0107] Using positional data from the two sensors, the processor can determine the orientation of the pickup unit 210. For this purpose, for example, the known positions and orientations of the two sensors relative to the center point C1 may be used. In addition, the orientation of the light source relative to the center point C1 may be known, and the processor may use this to determine the orientation of the pickup unit 210.

[0108] In the second case, we assume that the orientation of the pickup unit 210 can change due to yaw, roll, and tilt relative to a center point C2 fixed in space. In this case, the positional relationship between center points C1 and C2 is known. This information, in addition to the previously mentioned information, is used by the processor to determine the orientation of the pickup unit 210. In this case as well, there are three degrees of freedom, and it is possible to uniquely define the orientation using two sensors.

[0109] In the third case, we assume that both center points C1 and C2 can change position in space. In this case, there are six degrees of freedom, so additional information is needed to determine both the position and orientation of the pickup unit 210. This additional information can be obtained by using a third sensor that senses the zero-order diffraction beam. In this case, the processor uses position data from the first, second, and third sensors to determine the position and orientation of the pickup unit 210.

[0110] In the second and third cases described above, it was assumed that the collimating light source can emit a collimated light beam onto the diffraction grating. For this purpose, an orientation unit can be provided to change the orientation of the collimating light source. The processor can then be configured to control the orientation of the collimating light source. Furthermore, the processor may implement a feedback control loop that modifies the orientation of the light source based on the determined position and / or orientation of the device to ensure that the collimating light source continues to emit collimated light onto the center point of the diffraction grating.

[0111] Figure 7 shows a favorable method for determining the angle of the diffracted beam. In this figure, the diffracted beam passes through a pinhole 501 with radius R and an objective lens 502 before striking the sensor 503 at positions x, y. The distance between the objective lens 502 and the sensor 503 corresponds to the focal length f.

[0112] Light passing through a circular aperture is known to undergo diffraction. More specifically, an Airy pattern is created to include a central Airy disk surrounded by multiple concentric circles. The angle at which the first intensity minimum occurs, measured from the direction of the incident diffracted beam, is approximately as follows:

number

[0113] When using only the pinhole 501, the diffraction grating on the surface of the sensor 503 has a typical Airy pattern, i.e., a centrally bright disk surrounded by a group of bright and dark circles. The size of the Airy disk depends on the distance between the pinhole 501 and the sensor surface of the sensor 503. When the intensity of the incident light ray is weak, only the centrally bright disk can be clearly observed. The coordinates (e.g., x and y) of the Airy disk on the surface of the sensor 503 depend on the angle of incidence of the light beam in the transverse and longitudinal directions, respectively. As the angle of incidence changes, the coordinates change accordingly, even if the beam width widens due to divergence.

[0114] When using only the objective lens 502, a clear light spot of the Airy disk can be observed on the focal plane. The coordinates of the center of the Airy disk on the focal plane change with the change in the angle of incidence. Note that in some embodiments, both the pinhole 501 and the objective lens 502 are used.

[0115] To calibrate this system, the known incidence angle and the corresponding Airy disk coordinates are initially recorded as basic calibration data for the x and y directions, respectively. These data may be stored in the form of a lookup table.

[0116] The present invention has been described above using detailed embodiments. However, the present invention is not limited to these embodiments. Rather, various modifications are possible without departing from the scope of the invention as defined by the appended claims and equivalents.

[0117] Specific preferred embodiments of the present invention are described in the appended independent claims. Combinations of features from the dependent and / or independent claims may be used as appropriate, and are not limited to those described in the claims.

[0118] The scope of this disclosure includes any novel features or combinations of features, or any generalizations thereof, explicitly or implicitly disclosed, whether relating to the claimed invention or mitigating any or all of the problems addressed by the invention. The applicant hereby notifies that new claims may be made for such features during examination of this application or any further such application derived therefrom. In particular, with reference to the appended claims, the features of the dependent claims may be combined with the features of the independent claims, and each of the features of the independent claims may be combined in any suitable manner, not only in the specific combinations enumerated in the claims.

[0119] Features described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features described in the context of a single embodiment for the sake of brevity may also be provided separately or in any suitable secondary combination.

[0120] The term “comprising” does not exclude other elements or steps, and the terms “a” or “an” do not exclude plurals. Reference numerals in the claims should not be construed as limiting the claims.

Claims

1. A system for determining the orientation of a device, A diffraction grating is provided on the surface of the device, A collimating light source configured to generate an m-order light beam and an n-order light beam by diffraction by a diffraction grating by emitting collimated light onto the diffraction grating, wherein m is different from n, and both m and n are integers different from zero. A first photosensor having a first sensor surface and configured to detect the m-th order light beam, the first photosensor configured to detect a first position on the first sensor surface where the m-th order light beam is detected, A second photosensor having a second sensor surface and configured to detect the nth-order light beam, the second photosensor configured to detect a second position on the second sensor surface where the nth-order light beam is detected, A processor for determining orientation information relating to the orientation of the device based on the detected first position and the detected second position, A system equipped with these features.

2. The diffraction grating is at least locally flat, and perpendicular to the first direction at the center of the diffraction grating. The diffraction grating includes repeating pattern units in a second direction from the center point and in the direction opposite to the second direction from the center point. The system according to claim 1, wherein the pattern unit at the center point is elongated in a third direction.

3. The system according to claim 2, wherein the collimating light source is configured to emit a collimating light beam toward the center point of the diffraction grating.

4. The device described above, Yawing relative to the yaw axis, Tilt relative to the axis of rotation, Rolling relative to the roll axis, Its orientation can be changed by The orientation information of the device includes the yaw angle, tilt angle, and roll angle. Preferably, when the device is oriented to a predetermined default orientation, the yaw rotation axis extends in the third direction, the tilt rotation axis extends in the second direction, and the roll rotation axis extends in the first direction, according to claim 2 or 3.

5. The processor is configured to determine the orientation information based on the assumption that the center point of the diffraction grating remains in substantially the same position in space, or The processor is configured to determine the orientation of the device based on the assumption that the device moves while the predetermined center point of the device remains substantially in the same position in space, based on the detected first position and the detected second position and the known positional relationship between the center point of the diffraction grating and a predetermined center point of the device, or The system according to claim 4, further comprising a third photosensor having a third sensor surface and configured to detect a zero-order light beam, the third photosensor being configured to detect a third position on the third sensor surface where the zero-order light beam is detected, and the processor being further configured to determine the position of the device based on the detected first position, the detected second position, and the detected third position.

6. The system according to claim 5, wherein the processor is configured to control the orientation of the collimating light source, and the processor implements a feedback control loop that modifies the orientation of the light source based on a determined position and / or orientation of the device so as to ensure that the collimating light source continues to emit collimated light on the center point of the diffraction grating.

7. The system according to any one of claims 1 to 6, wherein m = -n, and m is preferably equal to 1.

8. The system according to any one of claims 1 to 7, wherein the first sensor, the second sensor, and the third sensor, if applicable, have fixed, known positions and orientations.

9. The system according to any one of claims 1 to 8, wherein the collimating light source is a coherent light source such as a laser.

10. The system according to any one of claims 1 to 9, further comprising a memory operably coupled to the processor, the memory comprising a lookup table containing data that correlates position data obtained from the first sensor, the second sensor, and optionally the third sensor with orientation and / or position information of the device.

11. The system according to any one of claims 1 to 10, wherein the first sensor, the second sensor, and optionally the third sensor are substantially flat sensors.

12. The first sensor, the second sensor, and optionally the third sensor are curved sensors such that each point on the corresponding sensor surface is substantially the same distance from a common reference point, and as far as can be seen in claim 5, the common reference point substantially coincides with the center point of the diffraction grating. The system according to any one of claims 1 to 10, wherein the first sensor, the second sensor, and optionally the third sensor are different parts of a single integrated sensor.

13. The system according to any one of claims 1 to 12, wherein the grid is a reflective grid or a transmissive grid.

14. A pick-and-place device for picking an electronic component from a first carrier and placing the component on a second carrier, comprising a pickup unit for picking the electronic component and a pickup unit for placing the electronic component, wherein the device further comprises the system described in any one of claims 1 to 13, and the diffraction grating is disposed on the pickup unit.

15. A method for determining the orientation of a device, wherein a diffraction grating is provided on the surface of the device, and the method is A step of generating an m-order light beam and an n-order light beam by diffraction by the diffraction grating by emitting collimated light onto the diffraction grating, wherein m is different from n, and both m and n are integers other than zero. A step of detecting the m-th order light beam using a first photosensor having a first sensor surface, wherein the detection step includes detecting a first position on the first sensor surface where the m-th order light beam is detected. A step of detecting the nth-order light beam using a second photosensor having a second sensor surface, wherein the detection step includes detecting a second position on the second sensor surface where the nth-order light beam is detected. A step of determining the orientation of the device based on the detected first position and the detected second position using a processor, Methods that include...

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