Pick-up unit and corresponding manufacturing method

Abstract

According to one aspect of the disclosure, a pick-up unit for a pick-and-place apparatus is provided. The pick-up unit includes a deformable shaft that is elongated in a longitudinal axis and has an outer surface with a flat portion. At least one diffraction grating is formed or arranged in the flat portion of the outer surface.

Description

Technical Field

[0001] Various aspects of this disclosure relate to pickup units for pickup and placement devices. Various aspects of this disclosure also relate to molds for manufacturing such pickup units, and pickup and placement devices including such pickup units. Background Technology

[0002] Pick-and-place devices are known apparatuses that can pick up electronic components from a first carrier and place them onto a second carrier. An exemplary application of a pick-and-place device is picking up a semiconductor die from a semiconductor wafer and placing the picked-up semiconductor die onto a printed circuit board. In this case, the semiconductor wafer or the carrier supporting the semiconductor wafer is the first carrier, and the printed circuit board is the second carrier.

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

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

[0005] When using a pickup unit to arrange electronic components as described above, a problem may arise where the force applied to the electronic components onto the second carrier is not constant during the arrangement of multiple electronic components. Typically, adhesives or other materials, such as solder, that hold and electrically attach the electronic components to the printed circuit board are applied to the second carrier in a predefined amount. When the electronic components are pressed into or onto the adhesive, some adhesive, which may be in at least partially liquid form, may flow out from beneath the electronic components during arrangement. The amount of outflow, and therefore the amount of adhesive remaining beneath the electronic components, depends particularly on the force applied to the second carrier. Therefore, when this force is not constant, the amount of adhesive applied between the electronic components and the second carrier may vary. This will result in variations in the height of the electronic components on the second carrier. For some applications, such as printed circuit boards with LED matrices, this type of variation is undesirable.

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

[0007] The pickup unit is typically a mobile device subject to changes in position and orientation. For example, the location where the pickup unit can place electronic components may differ slightly from the intended location. Similarly, the orientation where the pickup unit can place electronic components may differ slightly from the intended orientation. These changes may also be undesirable. Similar problems may occur when electronic components are arranged on a second carrier.

[0008] Determining the orientation and position of a pickup unit is often complex due to the large number of components in a pickup device. Furthermore, some known techniques for determining the orientation and / or position of a pickup unit are unavailable when the pickup unit is moving during operation. Summary of the Invention

[0009] According to various aspects of this disclosure, a pick-and-place device is provided, which solves the aforementioned problems.

[0010] According to a first aspect of this disclosure, a system for determining the orientation of an apparatus is provided, wherein a diffraction grating is arranged on the surface of the apparatus. This system includes a collimating light source configured to emit collimated light onto the diffraction grating, thereby generating an m-th order beam and an n-th order beam through diffraction by the grating, where m is different from n.

[0011] It is known that once the diffraction grating is illuminated by a collimated beam, it can generate different beams propagating in different directions. For a transmission diffraction grating, the angle between the incident collimated beam and the grating normal is... The angle between the m-th order beam leaving the diffraction grating The relationship between them is given below:

[0012] Equation 1

[0013] If the incident beam and the diffracted beam are on opposite sides of the normal to the grating surface, then and Both are positive, and where m is the diffraction order, ..., -2, -1, 0, +1, +2, ... It is the wavelength of the incident collimated light, and among which... It is the characteristic dimension of the diffraction grating, and this characteristic dimension should be greater than... If the incident beam and the diffracted beam are on the same side of the grating normal, then it is necessary to... It is considered negative.

[0014] For a reflection diffraction grating, the relationship is equal to:

[0015] Equation 2

[0016] If the incident beam and the diffracted beam are on opposite sides of the normal to the grating surface, then It is positive, and It is negative. If the beam is on the same side of the normal to the grating surface, then both angles are considered positive.

[0017] If the diffraction grating includes multiple regularly arranged slits, then This represents the distance from the center of one slit to the center of the slit immediately adjacent to it. Within the context of this disclosure, the integer m in equations 1 and 2 above is used to refer to different diffraction orders.

[0018] It should be noted that many different diffraction gratings conforming to Equations 1 and 2 above are known in the art. This disclosure is not limited to a particular form of diffraction grating.

[0019] The system according to the first aspect of this disclosure further includes a first optical sensor having a first sensor surface. The first optical sensor is configured to detect the m-th order beam. More specifically, the first optical sensor is configured to detect a first position on the first sensor surface where the m-th order beam is detected. Similarly, the system also includes a second optical sensor having a second sensor surface. The second optical sensor is configured to detect the n-th order beam. More specifically, the second optical sensor is configured to detect a second position on the second sensor surface where the n-th order beam is detected, where m is different from n, and where both m and n are integers other than zero. Preferably, m = -n, and m is preferably equal to 1.

[0020] The system also includes a processor for determining orientation information regarding the orientation of the device based on the detected first position and the detected second position.

[0021] Therefore, the diffraction grating is preferably at least partially flat and perpendicular to the first direction at its center point. Furthermore, the diffraction grating may include repeating pattern units from the center point along a second direction and from the center point along a direction opposite to the second direction. The pattern unit at the center point may be elongated along a third direction. For example, the pattern unit may be elongated along the third direction and have a width along the second direction. Corresponding to the slit. On both sides of the slit, there are arranged [features] with a width of [missing information]. Slender strips or slats. Repeating this pattern unit along a second direction and in the opposite direction will produce a regular pattern, wherein the distance between the centers of adjacent slits is equal to... .

[0022] The collimating light source can be configured to emit a collimated beam toward the center point of the diffraction grating. Furthermore, the device can be configured to change its orientation by yaw relative to the yaw rotation axis, tilt relative to the tilt rotation axis, and roll relative to the roll rotation axis. The device's orientation information can include the yaw angle, tilt angle, and roll angle. When the device is oriented in a predetermined default orientation, the yaw rotation axis can extend along a third direction, the tilt rotation axis can extend along a second direction, and the roll rotation axis can extend along a first direction.

[0023] The processor can be configured to determine the orientation of the device based on the following assumptions: a) the center point of the diffraction grating is held in a fixed position in space, b) the predetermined center point of the device is held in a fixed position in space, or c) both the center point of the diffraction grating and the center point of the device are not fixed in space.

[0024] Mechanical constraints can be used to determine which of the following assumptions applies: a), b), and c). For example, the movement of the device can be mechanically restricted to any of the aforementioned assumptions. Furthermore, in some cases, the difference in the determined orientation information between assumptions a) and b) may be small. In such cases, even if the actual movement of the device is according to assumption b), the orientation information can still be calculated based on assumption a). This can occur, for example, when the center point of the diffraction grating substantially coincides with the predetermined center point of the device. This may happen when the device is relatively flat along a first direction.

[0025] When the device moves according to assumption a), the processor can determine orientation information based on the detected first position and the detected second position.

[0026] When the device moves according to assumption b), the processor can 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 the predetermined center point of the device.

[0027] The system may also include a third optical sensor having a third sensor surface, wherein the third optical sensor is configured to detect a 0th-order beam. More specifically, the third optical sensor may be configured to detect a third location on the third sensor surface where a 0th-order beam has been detected.

[0028] When the device moves according to assumption c), the processor can 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 collimating light source should have a known orientation and position relative to the first, second, and third light sensors.

[0029] It should be noted that when the movement of the device is based on assumption a) or b), the latter calculation method used to determine the orientation and position of the device can be used equivalently.

[0030] The processor can be configured to control the orientation of the collimated 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 in which the orientation of the light source is changed based on the determined position and / or orientation of the device to ensure that the collimated light source continues to emit collimated light onto the center point of the diffraction grating. This is particularly relevant if the device moves according to assumptions b) or c).

[0031] The first and second sensors, and, if applicable, the third sensor, can have fixed and known positions and orientations. Furthermore, the collimated light source can be a coherent light source, such as a laser, whose orientation is known and / or can be determined. When determining the position and orientation of the device, the processor can use the position and orientation information of the light source and / or the first, second, and / or third sensors.

[0032] The system may also include a memory operatively coupled to the processor. The memory may include a lookup table containing data that correlates position data obtained from a first sensor, a second sensor, and optionally a third sensor with the orientation and / or position information of the device. Using a lookup table reduces the computational workload and time required to determine the orientation and position information.

[0033] The first sensor, the second sensor, and optionally the third sensor can be substantially flat sensors. Alternatively, the first sensor, the second sensor, and optionally the third sensor can be curved sensors, wherein each point on the corresponding sensor surface has substantially the same distance to a common reference point. With respect to the movement of the device, according to assumption a), the common reference point can substantially coincide with the center point of the diffraction grating. Furthermore, the first sensor, the second sensor, and optionally the third sensor can be different parts of a single integral sensor.

[0034] A diffraction grating can be a reflection grating or a transmission grating.

[0035] According to a first aspect of this disclosure, a pick-and-place device is provided for picking up an electronic component from a first carrier and placing the component onto a second carrier. The device may include a pick-up unit for picking up the electronic component and a pick-up unit for placing the electronic component. The pick-up unit for picking up the electronic component may be the same as the pick-up unit for placing the electronic component. The device may also include the system described above, wherein a diffraction grating is arranged on the pick-up unit.

[0036] According to a first aspect of this disclosure, a method for determining the orientation of an apparatus is provided, wherein a diffraction grating is disposed on the surface of the apparatus. The method includes the steps of: i) emitting collimated light onto the diffraction grating to generate an m-th order beam and an n-th order beam through diffraction by the diffraction grating; wherein m is different from n, and wherein both m and n are integers other than zero; ii) detecting the m-th order beam using a first photosensitive sensor having a first sensor surface, the detection including detecting a first position on the first sensor surface where the m-th order beam is detected; iii) detecting the n-th order beam using a second photosensitive sensor having a second sensor surface, the detection including detecting a second position on the second sensor surface where the n-th order beam is detected; and iv) determining the orientation of the apparatus using a processor based on the detected first position and the detected second position.

[0037] According to a second aspect of this disclosure, a pickup and placement device is provided for picking up an electronic component from a first carrier and placing the electronic component onto a second carrier. The device includes a pickup unit for picking up the electronic component and a pickup unit for placing the electronic component, the pickup unit being the same as the pickup unit for picking up the electronic component. A diffraction grating is disposed on the outer surface of the pickup unit, the diffraction grating including repeating patterned units along a first direction. The device further includes at least one collimating light source configured to emit collimated light onto the diffraction grating when picking up the electronic component from the first carrier and / or when placing the electronic component onto the second carrier. The system further includes: a sensor system for sensing an nth-order beam from the diffraction grating, where |n|>0; and a processor configured to determine, based on the sensed nth-order beam, a change in the length of the pickup unit along the first direction at the position of the diffraction grating when picking up the electronic component from the first carrier and / or when placing the electronic component onto the second carrier.

[0038] In short, according to the second aspect, the length change of the pickup unit along a direction perpendicular to the diffraction grating is detected using the offset of the nth-order beam. For example, during the process of picking up a semiconductor die, the pickup unit will slightly deform when it is pressed against the semiconductor die. More specifically, the length will decrease along a first direction perpendicular to the surface of the semiconductor die, and the length may increase along a second direction perpendicular to the first direction. By arranging the diffraction grating perpendicular to the first or second direction, it becomes possible to determine the corresponding length change by examining the nth-order beam. This is reflected in Equations 1 and 2, which indicate that if the distance... If the length changes, the diffraction angle will change.

[0039] Note that by examining the nth-order beam, the length change at the location of the diffraction grating can be determined. The length change does not need to be uniformly distributed across the pickup unit, nor is the force applied to the pickup unit causing the change limited to a specific direction. Typically, if the correlation between the cause of the length change and the length change itself is known, for example, by having a physical model for the pickup unit, the cause—i.e., force or strain—can be determined by monitoring the nth-order beam.

[0040] The processor can also be configured to determine a first force applied by the pickup unit to the electronic component and / or the first carrier based on a determined change in length when picking up the electronic component from the first carrier, and / or a second force applied by the pickup unit to the electronic component and / or the second carrier when placing the electronic component onto the second carrier. The force applied by the pickup unit to the electronic component or the first carrier is generally opposite to the reaction force applied by these components to the pickup unit. A similar consideration applies to the second force.

[0041] To determine the first and second forces, a physical model of the picking unit can be used. Such a model can, for example, describe how the picking unit deforms due to forces applied to its outer surface. This physical model can be tensor-based.

[0042] The device may also include a movable support unit, such as a robotic arm, on which a pickup unit is mounted. In this case, the processor can be configured to adjust the force applied by the movable support unit to the electronic component and / or the first carrier via the pickup unit when picking up the electronic component from the first carrier, and / or to adjust the force applied by the movable support unit to the electronic component and / or the second carrier via the pickup unit when placing the electronic component onto the second carrier. 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 disposed. For example, by moving the support unit relative to the movable support unit, the force applied during component pickup and / or placement can be adjusted.

[0043] The processor can be configured to determine a first force and / or associated length change during the pickup of an electronic component, compare the determined first force and / or associated length change with a first reference force and / or associated first reference length change, and generate a first comparison result. Additionally or alternatively, the processor can 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 force and / or associated second reference length change, and generate a second comparison result.

[0044] The first comparison result and the second comparison result can be used in a manual or automatic feedback control loop. In an automatic feedback control loop, the processor can be configured to adjust the force applied by the movable support unit to the electronic component and / or the first carrier through the pickup unit, based on the first comparison result and / or the second comparison result, when picking up the electronic component from the first carrier, and / or adjust the force applied by the movable support unit to the electronic component and / or the second carrier through the pickup unit, when placing the electronic component onto the second carrier.

[0045] In a manual feedback control loop, the processor can be configured to output a signal to the user corresponding to a first comparison result and / or a second comparison result. In this case, the processor can be configured to receive user input for adjusting the force applied by the movable support unit to the electronic component and / or the first carrier via the pickup unit when the electronic component is picked up from the first carrier, and / or for adjusting the force applied by the movable support unit to the electronic component and / or the second carrier via the pickup unit when the electronic component is placed onto the second carrier.

[0046] The pick-and-place device may also include a memory operatively coupled to a processor and holding a lookup table that associates the length change of the pick-up unit along a first direction at the location of the diffraction grating with the values ​​of forces and / or strains applied to the pick-up unit in relation to length contraction. Using a lookup table reduces the computational burden or time required to determine the values ​​of forces and / or strains applied to the pick-up unit in relation to length contraction.

[0047] The sensor system can also be configured to sense the m-th order beam from the diffraction grating, where m is different from 0 and n. In this case, the processor can be configured to determine, based on the sensed n-th order beam and the sensed m-th order beam, the change in length of the pickup unit along a first direction at the location of the diffraction grating when picking up the electronic component from the first carrier and / or when placing the electronic component onto the second carrier. Preferably, m equals -n, and n preferably equals 1.

[0048] The processor can be configured to determine the orientation of the pickup unit based on the sensed nth-order beam and the sensed mth-order beam when picking up an electronic component from a first carrier and / or when placing the electronic component onto a second carrier. This determination can be performed as described in conjunction with the first aspect of this disclosure.

[0049] If the orientation of the pickup unit is fixed, monitoring a single higher-order beam from the diffraction grating is sufficient to determine the length change, as long as the beam is not a 0th-order beam.

[0050] In some cases, such as when the pickup unit is in physical contact with an electronic component, a first carrier, or a second carrier, the orientation of the pickup unit can be changed. In these cases, the system according to the first aspect of this disclosure can be used to determine the orientation.

[0051] For example, if the sensor system includes a first sensor and a second sensor according to the first aspect of this disclosure, then the orientation of the pickup unit can be determined simply by observing the movement of the pickup unit according to the above assumption a), without considering... The precise value can then be determined using the detected first and second positions. The value of this value allows for the calculation of either the first or second force. This calculation can also take into account the determined orientation. For example, a change in the orientation of the pickup unit may result in a different force exerted by the pickup unit on the electronic component, the first carrier, or the second carrier compared to a scenario where the orientation has not changed.

[0052] The sensor system can be configured to sense a 0th-order beam from a diffraction grating. In this case, the processor can be configured to determine, based on the sensed 0th-order beam, the sensed nth-order beam, and the sensed mth-order beam, the change in length of the pickup unit along a first direction at the location of the diffraction grating when picking up an electronic component from a first carrier and / or when placing the electronic component onto a second carrier. Furthermore, the processor can also be configured to determine the orientation and position of the pickup unit based on the sensed 0th-order beam, the sensed nth-order beam, and the sensed mth-order beam when picking up an electronic component from a first carrier and / or when placing the electronic component onto a second carrier. The calculation of the position and orientation of the pickup unit can be performed using the system according to the first aspect of this disclosure.

[0053] The pick-and-place device may further include at least one orientation unit for changing the orientation of at least one collimating light source, wherein the processor is configured to control at least one orientation unit according to the determined orientation and / or position to ensure that light from at least one collimating light source illuminates a diffraction grating during each of a plurality of electronic components to be picked up from a first carrier, and / or to ensure that light from at least one collimating light source illuminates a diffraction grating during each of a plurality of electronic components to be placed onto a second carrier.

[0054] The first carrier can be a semiconductor wafer or a carrier supporting a semiconductor wafer, in which case the electronic component to be placed and arranged is a semiconductor die from that semiconductor wafer. Alternatively, the second carrier can be a printed circuit board. Or, the electronic component can be a packaged semiconductor die or device.

[0055] A diffraction grating can be a transmission diffraction grating or a transparent diffraction grating.

[0056] At least one collimating light source may include a first collimating light source and a second collimating light source. The first collimating light source is configured to emit collimated light onto a diffraction grating when an electronic component is picked up from a first carrier, and the second collimating light source is configured to emit collimated light onto the diffraction grating when an electronic component is placed onto a second carrier. In this case, the sensor system may include a first sensor subsystem and a second sensor subsystem. The first sensor subsystem is configured to sense the light beam from the diffraction grating when the electronic component is picked up from the first carrier, and the second sensor subsystem is configured to sense the light beam from the diffraction grating when the electronic component is placed onto the second carrier. The sensor system, or the first sensor subsystem and the second sensor subsystem, may each include a corresponding sensor for sensing a corresponding light beam from a corresponding order of the 0th, mth, and nth orders of the diffraction grating.

[0057] According to a second aspect of this disclosure, a method for picking up an electronic component from a first carrier is provided. This method includes the steps of: i) picking up the electronic component from the first carrier using a pickup unit, wherein a diffraction grating is disposed on the outer surface of the pickup unit, the diffraction grating comprising repeating patterned units along a first direction; ii) emitting collimated light onto the diffraction grating when picking up the electronic component from the first carrier; iii) sensing an nth-order beam from the diffraction grating, where |n|>0; and iv) determining, based on the sensed nth-order beam, a change in the length of the pickup unit along the first direction at the location of the diffraction grating when picking up the electronic component from the first carrier.

[0058] According to a second aspect of this disclosure, a method for placing an electronic component from a second carrier is provided. This method includes the steps of: i) placing the electronic component from the second carrier using a pickup unit, wherein an outer surface of the pickup unit is provided with a diffraction grating, the diffraction grating comprising repeating patterned units along a first direction; ii) emitting collimated light onto the diffraction grating when the electronic component is placed onto the second carrier; iii) sensing an nth-order beam from the diffraction grating, where |n|>0; and iv) determining, based on the sensed nth-order beam, a change in the length of the pickup unit along the first direction at the location of the diffraction grating at the position of the electronic component being placed onto the second carrier.

[0059] According to a third aspect of this disclosure, a pickup unit for a pickup and placement device is provided, the pickup unit including a deformable shaft that is elongated along a longitudinal axis and has an outer surface with a flat portion. The pickup unit also includes at least one diffraction grating formed or arranged in the flat portion of the outer surface. This pickup unit can be used in a pickup and placement device according to a second aspect of this disclosure.

[0060] The shaft is deformable, such that forces applied to the shaft during operation of the pick-and-place device cause deformation, which can be determined by the pick-and-place device according to the second aspect of this disclosure. For this purpose, the deformable shaft can be made of one or more polymers.

[0061] The deformable shaft may be a hollow deformable shaft defining a central hole. Furthermore, the pickup unit may also include a hollow tip portion fixedly connected to an end of the hollow deformable shaft. The hollow tip portion may have a central hole aligned with the central hole of the hollow deformable shaft to form a continuous central hole. The hollow tip may be made of a different material than the deformable shaft. In other embodiments, the hollow tip is integrally connected to the deformable shaft.

[0062] At least one diffraction grating may include the repetition of a first pattern unit along a first direction. This first direction may be perpendicular to or parallel to the longitudinal axis. It should be noted that this disclosure does not preclude other orientations of the diffraction grating relative to the longitudinal axis, such as placement at an angle between 40 and 50 degrees, preferably 45 degrees, relative to the longitudinal axis.

[0063] At least one diffraction grating may include the repetition of second patterned units along a second direction, which may be perpendicular to the first direction. Typically, when multiple diffraction gratings are used, each diffraction grating is provided with its own incident beam from a collimated source. To determine force, orientation, or position, as described in conjunction with the first and second aspects of this disclosure, each diffraction grating may be used individually, but components such as sensors may be shared. For example, as described above, only the first diffraction grating may be used to determine the force applied to the pickup unit, the orientation of the pickup unit, and / or the position of the pickup unit, and as described above, only the second diffraction grating may be used to determine the force applied to the pickup unit, the orientation of the pickup unit, and / or the position of the pickup unit. These results can then be combined to provide more accurate values ​​for the force applied to the pickup unit, the orientation of the pickup unit, and / or the position of the pickup unit.

[0064] According to a third aspect of this disclosure, a method for manufacturing the aforementioned pickup unit is provided. This method includes: providing a mold having an inner wall defining a mold cavity; providing a diffraction unit comprising a body having an outer surface on which a diffraction grating is disposed; and arranging the diffraction unit in the mold cavity, wherein the diffraction grating of the diffraction unit abuts against the inner wall. Next, molding material is cast into the mold cavity and the cast molding material is allowed to at least partially harden, thereby forming a body of cured molding material fixedly attached to the diffraction unit. As a final step, the body and the diffraction unit are removed from the mold. Additional curing or processing steps may be performed on the body and the diffraction unit to form the pickup unit.

[0065] The method may also include arranging a shaft in the mold cavity, preferably spaced apart from the diffraction unit, to form a central hole during a subsequent molding process.

[0066] According to a third aspect of this disclosure, a pickup and placement device is provided for picking up an electronic component from a first carrier and placing the electronic component onto a second carrier. This device includes: the pickup unit described above; at least one collimating light source configured to emit collimated light onto a diffraction grating when picking up the electronic component from the first carrier and / or when placing the electronic component onto the second carrier; a sensor system for sensing an nth-order beam from the diffraction grating, where |n|>0; and a processor configured to, based on the sensed nth-order beam, determine a change in the length of the pickup unit along a first direction at the location of the diffraction grating.

[0067] The pickup unit may be provided with a central hole as described above. In this case, the device may further include a pressure regulating unit connected to the central hole of the pickup unit. The processor may be configured to control the pressure regulating unit to reduce the pressure in the central hole for picking up electronic components using suction, and to increase the pressure in the central hole for placing electronic components. Attached Figure Description

[0068] To provide a more detailed understanding of the features of this disclosure, reference has been made to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings show only typical embodiments and should not be considered as limiting the scope thereof. The drawings are for ease of understanding of this disclosure and are not necessarily drawn to scale. The advantages of the claimed subject matter will become apparent to those skilled in the art when this specification is read in conjunction with the accompanying drawings, in which the same reference numerals are used to denote the same elements, and in the drawings:

[0069] Figure 1 The transmission diffraction grating (top) and the reflection diffraction grating (bottom) are shown.

[0070] Figure 2 The pick-and-place device according to this disclosure is shown schematically;

[0071] Figure 3 An embodiment of the pick-and-place device according to this disclosure is shown;

[0072] Figures 4A to 4D It shows Figure 3 Different detailed views of the device;

[0073] Figure 5 It shows the manufacturing process. Figure 3 The mold for the pickup unit of the device;

[0074] Figure 6 It shows the result of Figure 2 The various rotations determined by the system; and

[0075] Figure 7 A method for detecting the angle of a light beam according to one aspect of this disclosure is shown. Detailed Implementation

[0076] Figure 1 The transmission (top) and reflection (bottom) diffraction grating patterns are shown. In both cases, the collimated beam 3 is angled relative to the normal 2. The light is incident on diffraction grating 1. Due to diffraction, in addition to the 0th order beam 4, a higher order beam 5 is also generated.

[0077] exist Figure 1 The image shows two higher-order sub-beams, which are angled relative to the normal 2. and The two first-order beams. Both angles satisfy Equation 1. For both transmission and reflection diffraction gratings, the equation yields:

[0078] Equation 3

[0079] Equation 4

[0080] It can be seen that if the distance Change, then perspective and This will also change. Furthermore, if the diffraction grating changes orientation, the beams corresponding to the +1st and -1st orders will change their propagation paths in space. According to one aspect of this disclosure, changes in the orientation and length of the device can be monitored by arranging diffraction gratings on the device. The applicant has recognized that this particular monitoring method is particularly effective in pick-and-place devices requiring high-precision pickup and placement of electronic components. Moreover, such non-contact measurement techniques are particularly useful when inspecting pickup units.

[0081] Figure 2 A pickup and placement device 100 according to the present disclosure is schematically shown. The above-described device may correspond, for example, to the pickup unit of this pickup and placement device.

[0082] The device 100 includes a pickup unit 110, wherein a first diffraction grating 111 and a second diffraction grating 112 are disposed on the outer surface of the pickup unit 110. Each pattern 111, 112 includes a repetition of corresponding pattern units. The pattern units of the diffraction gratings 111, 112 may be different from each other. For example, the characteristic distances of the diffraction gratings 111, 112... And / or the construction can be different. In addition, for patterns 111 and 112, the direction in which the pattern units are repeated can be different.

[0083] The device 100 also includes a first collimating light source 121 and a second collimating light source 122, the orientation of which can be changed using corresponding orientation units 131 and 132.

[0084] The device 100 includes corresponding sensor systems 141 and 142 for sensing light beams from diffraction gratings 111 and 112, respectively. Each sensor system 141 and 142 includes three sensors 143: one sensor for sensing the 0th order, one sensor for sensing the +1st order, and one sensor for sensing the -1st order.

[0085] Device 100 includes a processor 150 configured to process signals from sensor systems 141, 142. Processor 150 controls a movable support unit 160 on which a pickup unit 110 is mounted.

[0086] The processor 150, together with collimating light sources 121, 122 and sensor systems 141, 142, can form a system for determining the orientation of the pickup unit 110, as will be explained below. Furthermore, additional light sources and sensor systems can be provided, for example, to determine the orientation, position, and / or length changes of the pickup unit 110 at various locations within the device 100, such as at the location where an electronic component is picked up from a first carrier, or at the location where an electronic component is placed onto a second carrier. Furthermore, implementations using fewer or more diffraction gratings on the surface of the pickup unit 110 are possible.

[0087] Figure 3 An embodiment of a pick-and-place device 200 according to the present disclosure is shown. It includes a disc conveyor 201 on which four pick-up units 110 are mounted. A semiconductor wafer 300 is also shown, the semiconductor wafer including a plurality of semiconductor dies 301 to be disposed on a second carrier 302. The semiconductor wafer 300 is disposed on a film or foil and is further provided with the ability to... Figure 3 A stage (not shown) that moves in the directions z and y is supported. In this case, the membrane or foil, or the membrane frame carrier to which the membrane or foil is attached, acts as the first carrier. Similarly, the second carrier 302 is supported by a structure capable of moving in the directions z and y. Figure 3 A stage (not shown) that moves in the directions x and y is supported. A suitable electric motor can be used to move the stage.

[0088] The process of picking up and placing semiconductor die 301 will be explained next.

[0089] In order to pick up semiconductor die 301 from wafer 300, the stage supporting semiconductor wafer 300 is moved so that the next semiconductor die on wafer 300 is aligned with the pickup unit 210_1.

[0090] To pick up the semiconductor die 301, the pickup unit 210 and the wafer 300 are moved toward each other. This can be done by driving the pickup unit 210 to move in the opposite direction to the x-direction, for example using... Figure 2 The movable support unit 160 shown is implemented by moving the stage supporting the semiconductor wafer 300 along the x-direction.

[0091] A needle-like element 303 is disposed on the back side of the semiconductor wafer 300. This element can be moved along the x-direction to press or push it onto the foil, thereby causing the semiconductor die 301 at this location to be at least partially separated from the rest of the wafer 300.

[0092] The pickup unit 210 is provided with a tip through which a suction force can be applied. Due to this force, the semiconductor die 301 is attached to the tip of the pickup unit 210. Next, the disc conveyor belt 201 is rotated clockwise to align the most recently picked-up semiconductor die 301 with the second carrier 302. Typically, the second carrier 302 is provided with discrete points of adhesive such as solder. Using a stage supporting the second carrier 302, the second carrier 302 is moved to align the empty space on the second carrier 302 with the pickup unit 210. Once aligned, 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 by moving the second carrier 302. When the pickup unit 210 is sufficiently close to the second carrier 302, the suction force in 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. It should be noted that when a semiconductor die is positioned on the second carrier 302, a new semiconductor die can be picked up from the semiconductor wafer 300. This is possible due to the arrangement of the multiple pick-up units 210 on the disk conveyor belt 201.

[0093] During the pick-up and placement process, the pick-up unit 210 can physically contact the semiconductor die 301. For example, the pick-up unit 210 can contact the semiconductor die before picking it up. In this case, the semiconductor die is positioned between the pick-up unit 210 on one side and the foil and needle element 303 on the other side. Similarly, during the placement of the semiconductor die 301, the pick-up unit 210 can push the semiconductor die 301 toward the second carrier 302.

[0094] To achieve a uniform pick-and-place process, the force applied to the semiconductor die 301 by the pick-up unit 210 is ideally constant throughout the process and from wafer to wafer. Similarly, the orientation of the pick-up unit 210 is preferably constant and / or known. For this purpose, the pick-and-place device 200 may be provided with a system for determining the orientation of the pick-up unit 210. This system uses a diffraction grating 211 arranged on the outer surface of the pick-up unit 210. A collimated light source, including a light source 221 and a collimating lens 221A, generates a collimated beam that perpendicularly illuminates the diffraction grating 211. The +1st and -1st order beams generated by the diffraction grating 211 are sensed using photosensitive sensors 241 and 242, each including a sensor surface 241A. More specifically, the photosensitive sensors output the detected beam coordinates on the sensor surface 241A.

[0095] exist Figure 3 In this configuration, the pick-and-place device 200 includes a single disc conveyor belt 201. Therefore, semiconductor dies 301 are picked up and placed from the same side using the same pick-up unit. In some applications, the orientation of the semiconductor 301 should be flipped between picking up and placing the semiconductor die 301. An example is a flip-chip application.

[0096] The orientation of the semiconductor die 301 can be flipped using a second disc conveyor belt arranged alongside the first disc conveyor belt 201. The second disc conveyor belt then receives the semiconductor die 301 from the first disc conveyor belt 201. More specifically, a pickup unit on the second disc conveyor belt, similar to the pickup unit on the first disc conveyor belt 201, receives the semiconductor die 301 from the first disc conveyor belt 201. The pickup unit on the second disc conveyor belt then performs the final placement of the semiconductor die 301 onto the second carrier 302.

[0097] Processors, such as Figure 2 The processor 150 is used to collect data from sensors 241 and 242 and to determine the length change at the position where the collimated beam illuminates the diffraction grating 211. This is in Figures 4A to 4D It is shown in more detail below.

[0098] like Figure 4B As shown, the pickup unit 210 contacts the semiconductor die 301, for example, because the semiconductor die is pushed towards the pickup unit 201 by the needle element 303. The force applied to the pickup unit 210 will deform the pickup unit.

[0099] exist Figure 4C and Figure 4DThe pickup unit 210 is shown in more detail below. The pickup unit 210 includes a deformable shaft 2101 with a central hole 2102. The outer surface 2103 of the pickup unit 210 includes a flat portion 2104, where a diffraction grating 211 is disposed. This pattern includes multiple pattern units that are elongated along the x-direction and repeat along the y-direction. It should be noted that... Figure 4C The slender shaft 2101 and the diffraction grating 211 in a deformed state are shown.

[0100] The pickup unit 210 also includes a tip 2105 having a central hole 2106. The tip 2105 is typically fastened or attached to the shaft 2101 such that the central hole 2102 is aligned with the central hole 2106. By reducing the pressure within the central hole 2101, a suction force can be generated at the tip 2105. Similarly, by increasing the pressure within the central hole 2102, the semiconductor die 301 can be pushed away from the tip 2105.

[0101] Several different techniques can be used to attach the tip 2105 to the shaft 2101. For example, a transition fit or an adhesive such as glue can be used. Alternatively, the shaft 2101 and the tip 2105 are integrally formed.

[0102] Figure 4D The image shows the shaft 2101 when no external force is applied to the pickup unit 210, while... Figure 4C The diagram illustrates the shaft 2101 when an external force along the x-direction is applied to the pickup unit 210. Due to this force, the shaft 2101 deforms along both the x and y directions. More specifically, the length of the shaft 2101 decreases along the x-direction, while the width of the shaft 2101 increases along the y-direction.

[0103] exist Figure 4C , Figure 4D In the diffraction grating 211, its elongated patterned units are arranged such that the longitudinal axis of the elongated patterned units is in the x-direction. Therefore, due to deformation along the y-direction, the effective value of the distance d in equations 3 and 4 changes, i.e., it becomes larger. This causes the +1st and -1st order beams to move away 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 location in the diffraction grating 211 where the collimated beam illuminates the diffraction grating 211. Using the physical model of the pickup unit 210, this deformation can be used to calculate the force applied to the tip 2105. This force is related to the reaction force applied to the semiconductor die 301.

[0104] Although shown as elongated patterned units along the x-direction, the diffraction grating 211 could similarly use elongated patterned units along the y-direction. However, such an arrangement would result in the generation of higher-order sub-beams in the xz-plane. In pickup and drop-off devices, the space available for arranging the required light source and sensor is typically smaller in this plane compared to the zy-plane.

[0105] After deformation and / or force have been established in pickup unit 210 and applied to pickup unit 210, the processor can control a driver to bring pickup unit 210 and semiconductor 301 into physical contact. For example, when pickup unit 210 is subjected to a driver such as... Figure 2 When the movable support unit 160, which may be in the form of a linear motor, is driven, the processor can control this unit to apply less or more force to the pickup unit 210. This adjustment can be performed simultaneously with the pickup of the semiconductor die 301. Alternatively, the adjustment can be made with respect to the next semiconductor die 301 to be picked up. In this way, the force applied to the semiconductor die 301 during pickup can be controlled in a uniform manner.

[0106] Although described in conjunction with the pickup semiconductor die 301, a similar method can be used when placing the semiconductor die 301 onto the second carrier 302. This typically requires the use of a separate collimating light source and a separate sensor. Because the components are preferably arranged in the zy plane, preferably, the photosensor emits the collimated beam onto the diffraction grating 211 along the x-direction. Then, sensors for detecting the resulting higher-order diffracted beams are arranged next to the photosensor along the y-direction and in the opposite direction. Figure 3 In the diagram, circles and a pair of triangles are used to indicate the location of the light source and the location of the light sensor used for monitoring during component placement.

[0107] In combination Figure 3 , Figures 4A to 4D The described pick-and-place device includes a movable support unit for moving the pick-up unit 210 in a single direction. This disclosure is not limited to such movable support units. In other embodiments, a robotic arm on which the pick-up unit is mounted is used.

[0108] Figure 5 A mold 400 for manufacturing the pickup unit 210 is shown. The mold 400 includes a holding housing 401 in which a plurality of mold components 402A-402C can be arranged. For this purpose, the holding housing 401 may include a sealing door 403, which can be secured to the rest of the holding housing 401 using sealing screws 404. By opening the sealing door 403, the mold components 402 can be removed from the holding housing 401 and the at least partially cured pickup unit 210.

[0109] Typically, mold components 402A and 402B are mirror copies of each other. Furthermore, mold component 402A and mold component 402C are copies of each other. It should be noted that... Figure 5 A mold component complementary to mold component 402C is not shown.

[0110] The inner walls of mold components 402A, 402B, and 402C define the outer surface of pickup unit 210. These walls also define mold cavity 405. Within mold cavity 405, a diffraction unit 406 is arranged, comprising a body having an outer surface on which a diffraction grating 211 is disposed. The diffraction unit 406 is arranged within mold cavity 405 such that the diffraction grating 211 faces the inner walls of mold components 402A, 402B, and 402C.

[0111] A shaft 407 is arranged in the mold cavity, wherein the shaft 407 is configured to realize the center hole 2102. Furthermore, on the upper surface, mold components 402A, 402B, and 402C collectively form a pair of pouring cups 408. After closing the retaining box 401, liquid molding material is poured into the pouring cups. Gas within the mold cavity can escape from the mold cavity through a gas venting channel 409. The molding material may, for example, include one or more resins and / or polymers.

[0112] Once at least partially cured, open the retaining box 401 to allow removal of mold components 402A-402C, shaft 406, and pickup unit 210. Optionally, additional processing may be performed on pickup unit 210 to further harden it.

[0113] Using the method described above, a pickup unit 210 in which the diffraction grating 211 is fixedly attached to the deformable shaft 210 is obtained. There are other options where the diffraction grating 211 can be formed on or within the deformable shaft 210. For example, a pattern corresponding to the opposite pattern of the diffraction grating can be formed on the inner wall of the mold components 402A-402C. In this case, the diffraction grating is formed during the molding process. Other imprinting techniques for pressing the diffraction grating into the deformable shaft are possible.

[0114] In the description so far, it has been assumed that the pickup unit 210 has a constant orientation during component pickup and during component placement. Under these conditions, it is sufficient to measure a single higher-order diffraction beam to determine the force or strain on the pickup unit 210. However, this assumption may not always hold, especially since the pickup unit 210 can be configured as a moving unit. Mechanical tolerances and clearances can cause the pickup unit 210 to exhibit characteristics such as... Figure 6 Explaining yaw, tilt, and roll. In this figure, it is assumed that the diffraction grating consists of pattern units that are elongated along the z-direction and repeat along the x-direction. Figure 6In this context, yaw is defined as rotation about the z-axis, roll is defined as rotation about the x-axis, and pitch is defined as rotation about the y-axis.

[0115] Figure 6 The center point C1 of the diffraction grating and the center point C2 of the pickup unit 210 are also shown as a whole. Here, it should be noted that... Figure 7 A cross-sectional view of the pickup unit 210 is shown, wherein the cross-section in the zy plane is shown as being in the middle of the pickup unit 210 along the x direction.

[0116] Now, the method for determining the orientation of the pickup unit 210 will be explained based on three possible assumptions about the movement of the pickup unit 210.

[0117] In the first case, it is assumed that the orientation of the pickup unit 210 may change due to yaw, roll, and tilt relative to a fixed center point C1 in space. In this case, a collimated light source emits a collimated beam onto the center point C1. Then, sensors are used to capture higher-order beams generated by diffraction. More specifically, in this case, two sensors will be sufficient to uniquely determine the orientation of the pickup unit 210. The orientation may correspond to the yaw angle, tilt angle, and roll angle.

[0118] When using two sensors, the position data obtained from these sensors includes four independent parameters, such as x1, x2, y1, and y2, where xn and yn represent the positions on the sensor surface where higher-order diffracted beams are detected. The orientation of the pickup unit 210 includes three degrees of freedom: yaw, tilt, and roll.

[0119] Using position data from two sensors, the processor can determine the orientation of the pickup unit 210. For this purpose, the processor can use the known positions and orientations of the two sensors relative to the center point C1. Alternatively, the orientation of the light source relative to the center point C1 can be known and used by the processor to determine the orientation of the pickup unit 210.

[0120] In the second case, it is assumed that the orientation of the pickup unit 210 may change due to yaw, roll, and tilt relative to a fixed center point C2 in space. In this case, the positional relationship between the center points C1 and C2 is known. In addition to the previously mentioned information, this information is used by the processor to determine the orientation of the pickup unit 210. Again, there are three degrees of freedom, allowing the use of two sensors to uniquely define the orientation.

[0121] In the third case, it is assumed that both center points C1 and C2 may change their positions in space. In this case, there are six degrees of freedom, requiring additional information to determine both the position and orientation of the pickup unit 210. This additional information can be obtained using a third sensor that senses the 0th-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.

[0122] In the second and third scenarios above, it is assumed that the collimated light source can emit a collimated beam onto the diffraction grating. For this purpose, an orientation unit can be provided to change the orientation of the collimated light source. The processor can then be configured to control the orientation of the collimated light source. Furthermore, the processor can implement a feedback control loop in which the orientation of the light source is changed based on the determined position and / or orientation of the device to ensure that the collimated light source continues to emit collimated light onto the center point of the diffraction grating.

[0123] Figure 7 An advantageous method for determining the angle of the diffraction beam is illustrated. In this figure, the diffraction beam passes through a pinhole 501 with radius R, and an objective lens 502, and then strikes a sensor 503 at positions x, y. The distance between the objective lens 502 and the sensor 503 corresponds to the focal length f.

[0124] It is known that light passing through a circular aperture undergoes diffraction. More specifically, an Airy pattern is produced, which comprises 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 given by the following:

[0125] Equation 5

[0126] Where R is the radius of the aperture, which corresponds to the radius of the pinhole 501 when light passes through the pinhole 501, and corresponds to half of the numerical aperture when light passes through the objective lens 502.

[0127] When only pinhole 501 is used, the diffraction grating on the surface of sensor 503 exhibits a typical Airy pattern, where a central bright spot is surrounded by a set of bright and dark circles. The size of the Airy disk depends on the distance between pinhole 501 and the sensor surface of sensor 503. When the incident beam has a weak intensity, only the central bright spot can be clearly observed. The coordinates of the Airy disk on the surface of sensor 503, such as x and y, depend on the incident angles of the beam in the lateral and vertical directions, respectively. As the incident angle changes, the coordinates change accordingly, even as the beam width expands due to divergence.

[0128] When using only objective lens 502, a clear 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 angle of incidence. It should be noted that in some embodiments, both pinhole 501 and objective lens 502 are used.

[0129] To calibrate this system, the known incident angles and the corresponding Airy disk coordinates along the x and y directions are first recorded as basic data for calibration. This data can be stored in the form of a lookup table.

[0130] The invention has been described above using detailed embodiments. However, the invention is not limited to these embodiments. Instead, various modifications are possible without departing from the scope of the invention as defined by the appended claims and their equivalents.

[0131] Specific and preferred aspects of the invention are set forth in the appended independent claims. Combinations of features from dependent and / or independent claims may be appropriately combined, not merely those set forth in the claims.

[0132] The scope of this disclosure includes any novel feature or combination of features, or any generalization thereof, explicitly or implicitly disclosed herein, whether or not it relates to the claimed invention or alleviates any or all problems solved by the present invention. The applicant hereby informs that new claims may be made for such features during the examination of this application or any such further application derived therefrom. Specifically, with reference to the appended claims, features from dependent claims may be combined with features from independent claims, and features from the respective independent claims may be combined in any suitable manner, not merely in the specific combinations listed in the claims.

[0133] Features described in the context of individual embodiments may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, various features described in the context of a single embodiment may also be provided individually or in any suitable sub-combination.

[0134] The term "comprising" does not exclude other elements or steps, and the terms "a" or "an" do not exclude multiple. Reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

1. A pick-up unit for a pick-and-place apparatus, comprising: a deformable shaft, which is elongated in a longitudinal axis and has an outer surface with a flat portion; and at least one diffraction grating formed in or arranged in the flat portion of the outer surface.

2. The pick-up unit according to claim 1, wherein the deformable shaft is a hollow deformable shaft defining a central bore.

3. The pick-up unit according to claim 2, further comprising a hollow tip portion fixedly connected to an end of the hollow deformable shaft, the hollow tip portion having a central bore aligned with the central bore of the hollow deformable shaft, thereby forming a continuous central bore.

4. The pick-up unit according to any one of the preceding claims, wherein the at least one diffraction grating comprises a repetition of first pattern units along a first direction.

5. The pick-up unit according to claim 4, wherein the first direction is perpendicular to the longitudinal axis.

6. The pick-up unit according to claim 4, wherein the first direction is parallel to the longitudinal axis.

7. The pick-up unit according to claims 4, 5 and 6, wherein the at least one diffraction grating comprises a repetition of second pattern units along a second direction.

8. The pick-up unit according to claim 7, wherein the second direction is perpendicular to the first direction.

9. The pick-up unit according to any one of the preceding claims, wherein the deformable shaft is made of one or more polymers.

10. A method for manufacturing a pick-up unit according to any one of the preceding claims, comprising: providing a mold having inner walls defining a mold cavity; providing a diffraction unit comprising a body having an outer surface on which a diffraction grating is provided; arranging the diffraction unit in the mold cavity with the diffraction grating of the diffraction unit against the inner walls; casting a molding material in the mold cavity; allowing the cast molding material to at least partially harden, thereby forming a body of solidified molding material fixedly attached to the diffraction unit; and removing the body and diffraction unit from the mold.

11. The method according to claim 10, further comprising arranging a shaft, preferably spaced apart from the diffraction unit, in the mold cavity to form the central bore during the subsequent molding process.

12. A pick-and-place apparatus for picking up electronic components from a first carrier and placing the electronic components on a second carrier, the apparatus comprising: a pick-up unit according to any one of claims 1 to 9; at least one collimated light source configured for emitting collimated light onto the diffraction grating when picking up electronic components from the first carrier and / or when placing electronic components on the second carrier; a sensor system for sensing an nth order beam of light from the diffraction grating, wherein |n| > 0; and a controller configured for controlling the pick-up unit and the at least one collimated light source. ​ a processor configured for determining, based on the sensed position of the nth order light beam, a change in length of the pick-up unit in the first direction at the position of the diffraction grating when picking up an electronic component from the first carrier and / or when placing an electronic component on the second carrier.

13. The pick-and-place apparatus according to claim 12, wherein the pick-up unit is configured as described in claim 2 or 3, the apparatus further comprising a pressure regulation unit connected to the central hole of the pick-up unit; wherein the processor is configured to control the pressure regulation unit to lower the pressure in the central hole for picking up an electronic component using suction and to raise the pressure in the central hole for placing an electronic component.

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