Manufacturing machine for electronic component production line with "defocus ranging" optical inspection system

Abstract

The invention relates to a manufacturing machine for a production line of electronic components. The manufacturing machine comprises: (a) a machine frame; (b) a manufacturing tool which is directly or indirectly movably or spatially fixedly mounted on the frame; and (c) an optical inspection system which is directly or indirectly movably or spatially fixedly mounted on the frame. The invention relates to an optical inspection system comprising: (c1) an irradiation device for irradiating an object with irradiation light, (c2) a camera system for recording a first image of the irradiated object by means of first measurement light and a second image of the irradiated object by means of second measurement light, (c3) an optical device and (c4) an image processing unit downstream of the camera system, the optical device is arranged in the beam path of the irradiation light, the first measurement light and / or the second measurement light. The element image processing unit is configured to determine a three-dimensional height map of at least a part of the object on the basis of the first image and the second image.

Description

Technical Field

[0001] This invention generally relates to the technical field of automated electronic component manufacturing. More particularly, it relates to a manufacturing machine having an optical inspection system for capturing and processing images, especially images of solder paste storage areas, components, and / or component carriers. Background Technology

[0002] Components with multiple discrete electronic components are typically fabricated on component carriers, such as circuit boards. In the field of mass production of electronic components, this is usually achieved using specialized production lines with conveyor systems for the component carriers, along which multiple manufacturing machines are arranged. Manufacturing machines on production lines for electronic component production include solder paste printers, typically multiple assembly machines arranged in a front-to-back configuration, and soldering machines, all arranged along the conveyor system.

[0003] In a solder paste printer, high-viscosity solder paste, in the form of individual solder paste reservoirs, is applied to a component carrier. This is typically done when a printing stencil is used.

[0004] In an assembly machine, electronic components are placed on component carriers. For this purpose, the assembly machine typically has an assembly head that (i) picks up the components to be assembled from a component pick-up position of a component supply mechanism, (ii) transports the picked-up components to an assembly area of ​​the assembly machine, where the individual component carriers to be assembled are located, and (iii) places the components transported to the assembly area onto the component carriers or onto the associated solder paste reservoirs at pre-defined component loading positions. For picking up components, a typical assembly head uses one or more component holding devices, such as vacuum grippers.

[0005] The solder paste reservoir is melted in the welding machine, so that the components assembled after the solder paste reservoir cools are permanently and electrically welded to the electrical component connection surfaces constructed on the component carrier.

[0006] To ensure a reliable soldering process, each solder paste reservoir needs to contain a predetermined amount of solder paste. That is, if the reservoir contains too little solder paste, the resulting solder joints may be mechanically unstable and / or, in particular, insufficiently conductive. If the reservoir contains too much solder paste, short circuits may occur between adjacent component connection surfaces during melting in the soldering machine.

[0007] DE 10 2013 216 196 A1 discloses an image processing system for detecting the three-dimensional (3D) structure of a solder paste reservoir applied to a component carrier. Here, based on the principle of "photometric stereo," the reservoir is illuminated at three different illumination angles and an image is captured for each, wherein each image has a separate intensity distribution related to the 3D shape of the reservoir.

[0008] Image analysis combining three images can determine the 3D structure of the corresponding solder paste reservoir, and thus its volume or the amount of solder paste.

[0009] To ensure reliable and precise assembly, a camera is needed to optically detect the component held by the component holder, and appropriate image processing is used to determine the precise spatial position of the held component relative to the component holder (tip). If necessary, existing deviations from the relative nominal position can then be identified and compensated for during placement by properly positioning the assembly head and / or rotating the component holder about its longitudinal axis. Furthermore, it can be identified whether the component is held correctly on the main surface or incorrectly on a smaller side of the component holder (the so-called upright position). Additionally, it can be identified whether the component is held in a tilted or skewed spatial orientation. Furthermore, it can be identified whether the held component has mechanical defects. Components held incorrectly or with defects are not permitted to continue processing and must generally be removed from the assembly process.

[0010] However, for reliable and accurate assembly, it is also necessary to determine the precise position of each component carrier to be assembled. In other words, only in this way can it be ensured that the components are accurately placed on the component carrier at their respective pre-defined assembly positions. The position of the component carrier is typically determined by optical measurement of at least one mark present on the component carrier.

[0011] For the optical inspection process of the aforementioned solder paste storage section, components, or component carriers, it is desirable, and indispensable for a fast, accurate, and reliable production process, to capture not only two-dimensional (2D) images but also three-dimensional (3D) images. In this context, 3D images are also referred to as height maps, and the corresponding spatial 3D structures are referred to as height features.

[0012] In the field of assembly technology, various techniques are known for optical 3D inspection. For example, a method and apparatus are known from DE 10 2018 102288 A1 for determining the orientation of an element held by an element holding device with a curved connecting contact by means of characteristic optical reflections. Characteristic optical reflections are produced when illumination light is incident on different cross-sections of the curved connecting contact at an oblique illumination angle.

[0013] DE 10 2016 122 494 A1 discloses an automated assembly machine having an image processing system configured to inspect the assembly contents of an electronic component, at least partially assembled on a component carrier. In this inspection, a three-dimensional reference height profile of the reference assembly contents of the electronic component associated with a reference component is used. The three-dimensional height profile of the component in the assembly contents is detected, and the detected height profile is compared with the reference height profile. If at least a portion of the height profile deviates from the corresponding portion of the reference height profile, the assembly contents are identified as defective. Otherwise, the assembly contents are identified as defect-free. Summary of the Invention

[0014] The objective of this invention is to enable (i) a solder paste storage unit and (ii) simple and reliable 3D inspection of components to be assembled and / or already assembled in a production line for electronic components.

[0015] This task is addressed by the subject matter of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0016] According to a first aspect of the invention, a manufacturing machine for a production line of electronic components is described. The manufacturing machine includes: (a) a frame; (b) a manufacturing tool, which is directly or indirectly movably or spatially fixedly mounted on the frame; and (c) an optical inspection system, which is directly or indirectly movably or spatially fixedly mounted on the frame. The optical inspection system has: (c1) an illumination device for illuminating an object with illumination light; (c2) a camera system for (i) capturing a (two-dimensional) first image of the illuminated object with the aid of a first measuring light and (ii) capturing a (two-dimensional) second image of the illuminated object with the aid of a second measuring light; (c3) optics; and (c4) an image processing unit placed after the camera system, the optics being arranged in the optical paths of the illumination light, the first measuring light, and / or the second measuring light. The illumination device, the optics, and / or the camera system are configured and arranged such that the first image has a first blur and the second image has a second blur, different from the first blur. Furthermore, the image processing unit is configured to determine a three-dimensional (3D) height map of at least a portion of the object based on the first image and the second image.

[0017] The manufacturing machine described is based on the understanding that, using the well-known "defocusing distance measurement" technology employed independently, particularly good optical inspection results can be achieved in a simple and effective manner in the field of electronic component production, and especially in manufacturing machines on production lines used to manufacture electronic components.

[0018] As an illustration, in the "defocus ranging" technique described in this article, a 3D height map is constructed from two images from different Z distances in the field of electronic component manufacturing.

[0019] This can be achieved by appropriately selecting sharpness settings for the two images, allowing each object pixel to have a characteristic blur in each image based on its individual distance from the corresponding focal plane. The height position of each individual object pixel can then be calculated from these characteristic blurs.

[0020] The "defocus ranging" technology can be implemented in the form of a device or in various ways through different embodiments described in more detail below. However, what all the embodiments described below have in common is that the corresponding "defocus ranging" optical inspection system can be implemented in a simple and particularly compact manner. Therefore, the described optical inspection system can also be applied to very narrow areas of the manufacturing machine.

[0021] Furthermore, the described optical inspection system can be implemented with at least no moving parts or only a few moving mechanical parts. This allows for simple manufacturing and results in high mechanical robustness of the inspection system. Additionally, there is no need to move the object between the capture of the first and second images. This allows two distinct, sharp images to be captured within a very short time interval, and partially or even simultaneously. Therefore, the 3D optical inspection process is accelerated compared to known 3D methods, resulting in a time advantage that is particularly advantageous in electronic component manufacturing due to the cost pressures that typically exist there.

[0022] Furthermore, an accurate image reconstruction of the object in focus can be calculated from the two images themselves. This is because artifacts can be eliminated, unlike image reconstruction with only one image. Compared to simple and still frequently used 2D detection, this improves accuracy and robustness when detecting marks, patterns, and barcodes, especially when the object in question is not precisely in focus of the optical imaging.

[0023] The object described can be any object within the scope of electronic component production that should be inspected in 3D optical form.

[0024] As mentioned above, the object can be, in particular, a solder paste reservoir, a component, or a marking on a component carrier.

[0025] The manufacturing tool can be any type of tool configured to perform at least one single production step or at least participate in such a step when producing or manufacturing electronic components constructed on a component carrier. Examples of manufacturing tools are assembly heads of assembly machines, squeegee devices in solder paste printers, and so on.

[0026] The image processing unit may be housed or mounted in or on a housing of the optical inspection system (not described in detail). Alternatively, however, the image processing unit may also be housed as a processor within a larger computing unit. Such a larger computing unit may, for example, be a master computer that controls and / or coordinates at least a portion of the operation of the manufacturing machine. Furthermore, the image processing unit may also be implemented non-physically in software form and / or in a hybrid form through a combination of software and hardware components.

[0027] According to one embodiment of the present invention, there is no spatial overlap between a first depth of field range associated with a first ambiguity in the optical imaging of a first image and a second depth of field range associated with a second ambiguity in the optical imaging of a second image.

[0028] The spatial difference between the two depth ranges can result in the determination of an accurate 3D height map even for relatively tall objects (where at least some of the object points of the object have relatively large height differences).

[0029] According to another embodiment of the invention, along the direction of light propagation, a first focal plane associated with the first image is located in front of the object plane of the object. A second focal plane associated with the second image is located behind the object plane of the object. This intuitively means that the two focal planes are located on different sides with respect to the object, or more precisely, with respect to the object plane of the optical inspection system. In other words, the object is located between the two focal planes.

[0030] The spatial arrangement of the object plane with respect to the two focal planes means that the determination of the 3D height map involves interpolation between first image information from the first image and second image information from the second image. Such interpolation advantageously allows for the determination of the 3D height map with particular accuracy and, especially, without error.

[0031] According to another embodiment of the invention, the first ambiguity or the second ambiguity is at least approximately zero. This means that the first focal plane associated with the first image, or alternatively the second focal plane associated with the second image, at least approximately coincides with the object plane of the object. In other words, one of the two images is the sharp image. The advantage of this is that by capturing the sharp image, a two-dimensional (2D) image is automatically provided in addition to the determined 3D height map. In the optical inspection, the 2D image information of the sharp 2D image can then be combined with the 3D height map information of the determined 3D height map. Thus, features of the object that cannot be identified by 3D inspection without using the 2D image information can also be optically identified.

[0032] The combined analysis of 3D height map information and 2D image information described herein can, for example, be used to reliably identify markings on low-contrast, typically barely visible, and / or reflective surfaces.

[0033] In this context, it should be noted that acquiring additional 2D images can be done in a time-neutral manner. A third image capture is not required beyond the two images needed to determine the 3D height map.

[0034] According to another embodiment of the invention, the irradiating light is incident on the object along the z-axis, and the first measuring light and the second measuring light leave the object along the z-axis (in the opposite direction).

[0035] The first and second measuring lights are generated in such a way that the illuminating light is at least partially reflected or (reverse) scattered on the surface of the object. Immediately following this reflection or scattering, the first and second measuring lights may not be immediately distinguishable from each other. Only on another path can the optical paths of the two "measuring lights" be separated into two spatially separate path segments, thereby capturing a first image on the first path segment and a second image on the second path segment.

[0036] The coaxial propagation of the illumination and measurement light along a defined z-direction or z-axis, as described here, has a significant advantage: a 3D height map can be generated without shadows. This applies in all cases where the z-direction is perpendicular to the object's plane.

[0037] In other 3D inspection methods (such as triangulation or photometric stereo), shadowed areas caused by interfering object edges may always exist due to the different angles of the illuminating and measuring lights. In such shadowed areas, 3D height maps cannot be accurately calculated or cannot be calculated at all. In contrast, the "defocusing" technique described in this embodiment is intuitively represented by two images being taken "frontally" and the object preferably also being frontally illuminated. Therefore, accurate, shadow-free height maps can be calculated even in areas with high object edges, allowing, for example, small elements near tall elements in a defined height map to be fully visible. For particularly accurate height maps, a telecentric camera system or a camera system with telecentric optics can be used on the object side.

[0038] According to another embodiment of the invention, the optical inspection system has a first beam splitter that spatially separates a portion of the illumination path of the illuminating light from a portion of the measurement path of the measuring light.

[0039] The first beam splitter may be a semi-transparent or partially optically transparent mirror or a beam splitter cube. Preferably, the illumination light is reflected by the first beam splitter, and the measurement light passes through the first beam splitter, if necessary, induced by refraction within the first beam splitter with a slight parallel offset.

[0040] According to another embodiment of the invention, at least one other illumination light for the object is coupled in by reflection at a first beam splitter, wherein the other illumination light illuminates the object at an angle different from the illumination light.

[0041] As described above, according to this embodiment, the illumination light is directed vertically upwards along the z-direction, which is perpendicular to the plane of the object on which it is located. Therefore, another illumination light strikes the object at an angle. Depending on the angle of inclination, in this embodiment, shadows appear at most in the other illumination light. There is no need to worry about shadows in either the illumination light or the measuring light, because both the illumination light and the measuring light do indeed strike or depart from the object along the z-direction.

[0042] In this document, the directions or angles of different illumination lights are given with respect to the z-direction. This means that the illumination light is so-called 0° illumination. The other illumination light may, for example, strike the object at an angle of at least approximately 30°, 60°, 70°, or 80°.

[0043] Preferably, in addition to the first illumination light, there is a second illumination light, and if possible, there is a third illumination light or even a fourth illumination light.

[0044] Depending on the amount of additional illumination light, the corresponding illumination angle may include any selection from the angles described above, which are at least approximately 30°, 60°, 70°, or 80°.

[0045] Additional oblique illumination, including at least one other illumination light, can advantageously enable the determination of 3D height maps with particular precision. This is especially applicable to objects with "visually problematic surfaces," such as glossy surfaces or surfaces with optically matte structural features on matte surfaces.

[0046] According to another embodiment of the invention, the irradiating light and another irradiating light have different colors.

[0047] By appropriately combining light colors or the spectral distributions of different irradiated lights, inspection results that are less prone to error can be achieved based on the corresponding optical conditions. Here, optical conditions can be determined in particular by the optical properties of the object's surface, such as color and reflectivity (glossy or matte). This also applies to optional (in 2D image capture) identifiable markings, especially if the marking has low contrast relative to the rest of the object's surface.

[0048] According to another embodiment of the invention, the optical device has at least almost no chromatic aberration.

[0049] In the absence of chromatic aberration (in imaging optics including achromatic lenses), it is advantageous to ensure that each object point is imaged onto the image point with a small circle of divergence. This is particularly useful for illumination scenarios with different illumination colors, and is especially meaningful when the object point is relatively far from the focal plane used to measure the light.

[0050] According to another embodiment of the invention, the optical device is telecentric.

[0051] Telecentric optics can be configured to have object-side and / or image-side telecentricity. In particular, with image-side telecentric imaging optics, the object point is located at the same position in both images. The imaging scale does not change when the object point is presented at another z-distance (the distance to the focal plane of the camera system on the object side). Therefore, advantageously, the distance between the high and low height features of the object is the same across all z-distances. Consequently, no shadows are cast on small components near the edges of tall objects, as only the perpendicular measuring beam contributes to imaging.

[0052] According to another embodiment of the invention, a camera system is configured to capture a (two-dimensional) third image of an illuminated object by means of a third measuring light, wherein the illumination device, optics and / or camera system are configured and arranged such that the third image has a third ambiguity, which is different from both the first and second ambiguities, and wherein an image processing unit is set up to further determine a three-dimensional (3D) height map based on the third image.

[0053] By considering more than two images from different distances, more optical information can be acquired when determining or calculating height maps. This not only improves inspection accuracy but also, in particular, expands the range of height measurements through further image acquisition. However, since information technology processing of two images by an image processing unit is sufficient for many applications, this document describes the determination of 3D height maps from only two images. All conclusions drawn herein similarly apply to multiple image acquisitions from different focal distances.

[0054] According to another embodiment of the invention, the manufacturing machine is an assembly machine. Furthermore, the manufacturing tool is an assembly head configured to: (i) pick up electronic components from component pick-up positions of a component supply mechanism; (ii) transport the picked-up components to an assembly area of ​​the assembly machine, where a component carrier to be assembled is located; and (iii) place the components transported to the assembly area onto the component carrier at predetermined component loading positions.

[0055] The described construction of the assembly machine is based on the understanding that the aforementioned "defocusing distance measurement" technology can be applied particularly advantageously and beneficially in the field of assembly technology.

[0056] Therefore, it is possible to identify misaligned components with particular reliability. In particular, it is possible to identify (undesirable) misalignment angles with respect to the longitudinal axis of component holding devices, such as suction claws. That is, the misalignment angle can be precisely determined from the different height values ​​of two different edges of the relevant component. If the misalignment angle exceeds a certain tolerance value, the misaligned component should be removed from the assembly process to prevent incorrect assembly.

[0057] Furthermore, it can accurately and reliably identify overturned components with bent connecting contacts (so-called gull-wing components). This also helps prevent incorrect assembly. Additionally, wear tests can be performed on the tips of the component holding device, especially the front face of the suction claw. This wear test allows for the timely replacement of defective or worn component holding devices.

[0058] According to another embodiment of the invention, the camera system is spatially fixedly mounted directly or indirectly on the assembly head. This has the advantage that the "defocusing rangefinder" camera system moves automatically as the assembly head moves. Therefore, for example, the component carrier to be assembled can be inspected planarly or at different locations on the component carrier without requiring a positioning system for the camera system itself.

[0059] Furthermore, in a suitable assembly machine architecture, components to be assembled can be inspected with high precision using 3D optical methods before being received by the assembly head or before being received by the component holding device of the assembly head. Before placing the components, the volume and / or shape of the solder paste reservoir can also be measured at the placement position using the assembly head. Moreover, after assembly, at least a portion of the assembly contents can be optically inspected in 3D. In this context, the assembly contents should be understood as a whole composed of multiple assembled electronic components.

[0060] According to another embodiment of the invention, the camera system is spatially fixedly mounted directly or indirectly on a frame. Therefore, the "defocus ranging" technique described in this document enables reliable 3D inspection of components housed on the assembly head or on a component holding device housed on the assembly head in a simple manner.

[0061] According to another embodiment of the invention, the manufacturing machine is a solder paste printer. The described manufacturing machine, a solder paste printer, is based on the understanding that the aforementioned "defocusing" technique can also be used particularly advantageously and beneficially in conjunction with circuit boards or component carriers. Therefore, the volume and / or 3D shape of the solder paste reservoir printed by means of printing methods, especially screen printing methods, in terms of the quality of the applied solder paste can be studied before the component carrier is supplied, and component carriers printed with defective solder paste will not be supplied to the assembly process at all.

[0062] According to another embodiment of the invention, the camera system has (a) a first image sensor for capturing a first image and (b) a second image sensor for capturing a second image, wherein the two image sensors are spatially fixed with respect to optics and / or to illumination devices. This has the advantage that no movable parts of the optical inspection system are required to capture two images, and the images can be captured simultaneously without additional time loss.

[0063] The different levels of blur in two images can be achieved simply by separating two image sensors (which could be, for example, a traditional CCD or CMOS camera chip) at different distances from the optics. Intuitively, this means the two image sensors are located at different focal lengths relative to the object.

[0064] According to another embodiment of the invention, the optical inspection system further includes a second beam splitter that spatially separates a portion of the first measurement optical path of the first measurement light from a portion of the second measurement optical path of the second measurement light.

[0065] In this context, spatial separation can be understood as two measurement beams, namely a first measurement beam and a second measurement beam, first leaving the object along a common measurement beam path (here, the propagation directions of the two measurement beams in the common measurement beam path are preferably antiparallel to the direction of at least a portion of the irradiating light incident on the object). A second beam splitter is then used to split the common measurement beam path into two measurement beam paths, namely the first measurement beam path and the second measurement beam path.

[0066] The second beam splitter can also be a semi-transparent or partially optically transparent mirror or a beam splitter cube. Preferably, one of the two measurement beams is reflected by the second beam splitter, and the other of the two measurement beams passes through the first beam splitter with a slight parallel offset if necessary, the parallel offset being caused by refraction in the first beam splitter.

[0067] By using a second beam splitter, it is possible to achieve, in a particularly simple and advantageous manner, that at least the optical inspection system does not require mechanically movable parts.

[0068] Therefore, the optical inspection system can possess high mechanical robustness and / or high thermal stability in the reliable establishment of accurate 3D height maps. Furthermore, the second beam splitter allows for the simultaneous acquisition of two images, enabling particularly rapid determination of the 3D height map.

[0069] According to another embodiment of the present invention, the first image sensor is a transparent image sensor that detects the first measuring light, and the second measuring light passes through the transparent image sensor to be detected by the second image sensor.

[0070] Intuitively, the first image sensor uses a first measurement light to extract a portion of the total measurement light scattered back by the object and allows the remaining second measurement light to pass through, thus reaching the second image sensor. This means that, along the propagation direction of the measurement light, the first measurement light, as part of the total measurement light, passes through the first image sensor and stops.

[0071] By using a transparent image sensor, the aforementioned additional component, the "second beam splitter," can be conveniently omitted, while still allowing two images to be captured simultaneously.

[0072] According to another embodiment of the invention, the camera system has only one unique image sensor that can be spatially positioned about an object plane and / or about optics, so that a first image can be captured in a first position of the unique image sensor and a second image can be captured in a different second position of the unique image sensor.

[0073] From a device perspective, the mobility or displaceability described by image sensors has the following advantages: only one image sensor is needed to capture two images, and thus an optical inspection system can be implemented in a simple and, in particular, cost-effective manner.

[0074] Regardless of how to achieve the spatial localization of a unique image sensor, the corresponding "defocus ranging" measurement process (with two image captures) can be implemented as follows: 1. Position the only image sensor at the first position Z1.

[0075] 2. Take the first image.

[0076] 3. Position the only image sensor at the second location Z2.

[0077] 4. Take a second image.

[0078] Therefore, the result is that there are two images from which a 3D height map can be determined from the relative blurriness of the object pixels contained within them.

[0079] According to another embodiment of the invention, the camera system has only one unique image sensor, which is fixedly arranged with respect to the object plane and / or with respect to the optical space. Furthermore, the optics are adaptive in terms of focus, such that (i) in a first state, a first image can be captured by the unique image sensor using a first focus, and (ii) in a second state, a second image can be captured by the unique image sensor using a second focus.

[0080] The advantage of using adaptive optics is that the number of components in the optical inspection system can be kept small, so that the "defocus ranging" technology can be integrated into the described manufacturing machine in a simple and cost-effective manner.

[0081] Adaptive optics can, in principle, be any optical refractive and / or diffractive component capable of changing the focal length. Here, only the so-called "liquid lens" or electrodynamic objective is mentioned as an example. Besides the fact that liquid lenses can be realized in a spatially compact and mechanically stable manner, they offer the advantage that the focal plane can be moved particularly quickly, for example, within 10 milliseconds. In particular, by changing the aperture of the adaptive optics, the sharpness of the image can be altered to obtain two distinctly different, less sharp images. Changing the aperture does not necessarily mean changing the diameter of a circular aperture. The aperture can also be changed through arbitrary, position-dependent transmission within a pre-defined aperture range.

[0082] Regardless of how the adaptive optics are implemented, the "defocus ranging" measurement process (with two image captures) can be implemented as follows: 1. Adjust the adaptive optics so that the focal plane is located at the first position Z1.

[0083] 2. Take the first image.

[0084] 3. Adjust the adaptive optics so that the focal plane is located at the second position Z2.

[0085] 4. Take a second image.

[0086] Therefore, the result is that there are two images, from which a 3D height map can be determined from the relative blurriness of the object pixels contained within them.

[0087] According to another embodiment of the invention, the optical device has chromatic aberration, and the irradiated light has at least a first irradiated color and a second irradiated color. Furthermore, a first measuring light is associated with the first irradiated color, and a second measuring light is associated with the second irradiated color.

[0088] The implementation method utilizing the physical optical properties of chromatic aberration has the advantages of eliminating the need for spatially moving parts in the optical inspection system, and keeping the number of optical components relatively small. This ensures high robustness and thermal stability of the optical inspection system.

[0089] In this context, "associated with" should be understood as primarily capturing the first image with the first illumination color and primarily capturing the second image with the second illumination color. This does not exclude a certain degree of "color mixing" that remains within the boundaries.

[0090] According to another embodiment of the present invention, a first image can be captured in a first operating state of the optical inspection system, in which an object is illuminated using a first illumination color, and a second image can be captured in a second operating state of the optical inspection system, in which an object is illuminated using a second illumination color.

[0091] Intuitively, in this implementation, which is particularly simple to implement with respect to the camera system, the images are captured in two separate images in time. Specifically, this means that a first image is captured first with a first illumination color, and then a second image is captured with a second illumination color. There are then two images, and a 3D height map can be calculated from the relative sharpness of these two images using a "defocusing" technique.

[0092] According to another embodiment of the invention, the camera system has a spectral resolution image sensor configured to extract a first image and a second image from a whole image of an illuminated object captured using both a first illumination color and a second illumination color. This embodiment has the advantage of requiring only a single image capture, as opposed to the above-described embodiment which is also based on chromatic aberration effects. This advantage, however, (currently at a relatively low cost) comes at the consequence that the image sensor must have at least a certain spectral resolution.

[0093] The spectral resolvability of an image sensor can be achieved, for example, by making the pixels on the image sensor color-sensitive. For instance, a first sensor pixel may preferably detect a first illumination color, and a second sensor pixel may preferably detect a second illumination color.

[0094] Other advantages and features of the present invention will become apparent from the following exemplary description of the presently preferred embodiments. Attached Figure Description

[0095] Figure 1 A manufacturing machine is shown according to one embodiment of the present invention.

[0096] Figure 2 An optical inspection system with a camera system is shown, having a first image sensor and a second image sensor arranged at different distances from a beam splitter, wherein the beam splitter splits a common measurement light into a first measurement light associated with the first image sensor and a second measurement light associated with the second image sensor.

[0097] Figure 3 An optical inspection system with a camera system is shown, which has a unique image sensor that is movable relative to the optics.

[0098] Figure 4An optical inspection system with a camera system is shown, which has a first image sensor and a second image sensor arranged one behind the other in a common measurement optical path, wherein the second image sensor is a partially transparent image sensor.

[0099] Figure 5 An optical inspection system with a camera system is shown, featuring a unique fixed image sensor and adaptive optics.

[0100] Explanation of reference numerals in the attached figures: 100 Manufacturing Machines / Automatic Assembly Machines 102 racks 104 Fixed support rail 106 movable support arm 108 Displaceable assembly components Assembly Area 110 112 Conveying device 114 Component Supply System 115 Component Suppliers 116 Component Pickup Location 118 Control Mechanism 118a data cable 130 Manufacturing tools / assembly heads 120a Optical inspection system for (fixed) components 120b (Portable) Optical Inspection System for Circuit Boards 190 Component Carrier / Circuit Board 192 Electronic Components 220 Optical Inspection System 230 Irradiation Device 230a Irradiation light / irradiation path 232 Another irradiation device 232a Another illumination beam / another illumination path 240 camera system 242 First Image Sensor 242a First measurement light / first measurement path 244 Second Image Sensor 244a Second Measurement Light / Second Measurement Path 246 Common measurement light / Common measurement path 250 Optical Components 252 Lens 262 First beam splitter 264 Second beam splitter 260 Image Processing Units 295 objects Z1 distance from the first image sensor Distance of Z2 from the second image sensor F1 First focal plane F2 Second focal plane 340 camera system 342 The only image sensor 342a First measurement light / first measurement path 344a Second Measurement Light / Second Measurement Path 440 camera system 442 First Image Sensor 442a First Measurement Light 444a Second Measurement Light 444 Second Image Sensor (Transparent) 540 camera system 542 The only image sensor 550 (Adaptive) Optics 552 (Modible) Lens 552a Moving. Detailed Implementation

[0101] It should be noted that, in the following detailed description, features or components that are identical or at least functionally identical according to another embodiment are given the same reference numerals or are given reference numerals in the last two digits as the reference numerals of the corresponding identical or at least functionally identical features or components. To avoid unnecessary repetition, features or components already explained by means of the embodiments described above will not be elaborated in detail thereafter.

[0102] Furthermore, it should be noted that the embodiments described below are merely limited choices of possible variations of the invention. In particular, it is possible to combine features of the various embodiments with each other in a suitable manner, so that those skilled in the art can regard many different embodiments as clearly disclosed using the variations explicitly shown herein.

[0103] It should also be noted that spatially related terms, such as "front" and "back," "top" and "bottom," "left" and "right," etc., are used to describe the relationship of one element relative to another element or other elements as shown in the figure. Therefore, spatially related terms can be applied to orientations different from those shown in the figure. However, it should be understood that for ease of description, all these spatially related terms refer to the orientation shown in the figures and are not necessarily limiting, as in use, the corresponding devices, components, etc., may take orientations different from those shown in the figures.

[0104] Figure 1 A manufacturing machine 100, configured as an automated assembly machine, is illustrated in schematic. This machine is used to assemble electronic components 192 onto a component carrier, or circuit board 190. The manufacturing machine 100 has a frame 102 as a fixed support structure.

[0105] A fixed support rail 104 is mounted or constructed on the frame 102, extending along the y-direction. A support arm 106 is mounted on the fixed support rail 104, extending along the x-direction and movable along the y-direction by means of a drive motor (not shown). The corresponding movable direction is indicated by a double arrow "Y". An assembly element 108 is mounted on the support arm 106, movable along the x-direction by means of another drive motor (also not shown). The corresponding movable direction is indicated by a double arrow "X". The component support rail 104, support arm 106, and assembly element 108, together with the two drive motors (not shown), constitute a so-called planar positioning system, by means of which a manufacturing tool 130 configured as an assembly head can be positioned in the xy-plane.

[0106] Assembly of the component carrier 190 takes place in the assembly area 110. Before assembly, the component carrier 190 to be assembled is conveyed into the assembly area 110 by means of a conveying device 112, such as a conveyor belt. After at least partial assembly of the component 192, the component carrier 190 is transported away by means of the conveying device 112. The corresponding conveying direction is... Figure 1 The arrow T is used to represent the two.

[0107] As from Figure 1 As can be seen, the assembly head 130 is fixed to the assembly component 108. By appropriately manipulating a drive motor (not shown), the assembly head 130 can be moved between the component pick-up position 116 of the component supply system 114 and the assembly area 110. A control mechanism 118, responsible for the frictionless assembly process in a known manner, is communicatively coupled to the assembly head 130 via a data line 118a (shown in dashed lines) and a drive motor (not shown). Here, the assembly head 130 moves to the component pick-up position 116, where the component 192 is received. The assembly head 130 then moves together with the received component 192 into the assembly area 110, where the component 192 is placed on the provided component carrier 190. The assembly head 130 then moves "emptily" back to the component supply system 114, where it re-receives the component 192.

[0108] As by Figure 1As can be seen, the automatic assembly machine 100 also has two optical inspection systems, namely the first optical inspection system 120a and the second optical inspection system 120b. However, it has been pointed out at this point that the manufacturing machine according to the invention may also have only a single optical inspection system.

[0109] The first optical inspection system 120a is fixedly, or spatially fixedly, mounted on the rack 102, and according to the embodiment shown herein, is used to perform 3D measurement on the component 192 received by the assembly head. For this purpose, the assembly head 130 is positioned above the optical inspection system 120a, so that the received component 192 reaches the inspection area of ​​the optical inspection system 120a. In this 3D component measurement, for example, component damage can be identified with high reliability. Furthermore, for example, it can be identified whether the received electronic component 192 is misaligned and received by the associated component holding device, which would lead to incorrect assembly of the associated component 192. Furthermore, the accurate angular position of the received component 192 can be measured. When placing the associated component 192, the angular position deviation can then be compensated appropriately by rotating the corresponding component holding device, thereby placing the associated component 192 on the component carrier 190 at the correct angular position.

[0110] According to the embodiment shown herein, a second optical inspection system 120b is used to precisely measure markings mounted on the upper side of the component carrier 190 to be assembled. This allows identification of the precise spatial position of the component carrier 190 within the assembly area 110, and takes into account when positioning the assembly head 130 that the components 192 are also precisely placed on the component carrier 190 at a defined target position. According to the embodiment shown herein, the second optical inspection system 120b is mounted on the assembly head 130 and moves together with the assembly head 130 to measure the markings on the component carrier 190.

[0111] However, the second optical inspection system 120b can also be used, in a particularly advantageous manner, to measure the so-called assembly contents, i.e., to measure the assembled components in 3D, after at least partial assembly. This allows for the identification of possible malassemblies, and, if necessary, the removal of the associated at least partially assembled component carrier 190 from subsequent processing. Furthermore, the associated solder reservoir, on which the connector of component 192 rests, can be measured in 3D before assembling component 192. This allows for verification that the shape and / or volume of the solder reservoir is within specified tolerances.

[0112] Figure 2An optical inspection system 220 according to a first embodiment of the present invention is shown. The inspection system 220 has an illumination device 230 that guides illumination light 230a onto an object 295 to be inspected. The illumination path of the illumination light 230a extends via reflection through a first beam splitter 262. The illumination device 230 and the first beam splitter 262 are arranged and configured such that the illumination light 230a strikes the object 295 from above.

[0113] As explained earlier, object 295 can be the structure of any arbitrary preferred three-dimensional spatial entity, which should be measured in 3D within the scope of electronic component manufacturing and especially within the scope of assembly technology. Examples include electronic components to be assembled, already assembled electronic components, solder paste storage compartments, and markings on component carriers to be assembled.

[0114] The optical inspection system 220 also includes a camera system 240 that detects the object 250 from above via optics 250 and a first beam splitter 262. The camera system 240 has two image sensors: a first image sensor 242 and a second image sensor 244. The second beam splitter 264 is located above the optics 250 and splits a common measurement light 242c emitted upwards from the object 295 through the optics 250 along a common measurement path into two beams. In this document, these sub-beams are referred to as the first measurement light 242a and the second measurement light 244a. Here, the first measurement light 242a propagates along a first optical measurement path (in transmission) extending from the second beam splitter 264 to the first image sensor 242. Correspondingly, the second measurement light 244a propagates along a second optical measurement path (in reflection) extending from the second beam splitter 264 toward the second image sensor 244.

[0115] The two image sensors 242 and 244 are spaced apart from the second beam splitter 264 at different distances. The corresponding distances are... Figure 2 In Chinese, they are represented by "Z1" and "Z2".

[0116] According to the embodiment shown herein, the optical device 250 is a refractive optical device with a fixed focal point (distance). The optical device 250 has a plurality of lenses 252, wherein... Figure 2 Two lenses 252 are shown as an example.

[0117] Optical device 250 is preferably a telecentric imaging optical device. Telecentric imaging optical devices have the advantage of constant magnification, especially in relation to the "defocusing distance measurement" principle described herein.

[0118] This is because it maintains a distance independent of the object 295 from the imaging optics 250. This means that even if the object 295 moves slightly, the image of the object 295 (on both image sensors 242, 244) remains the same size. Accordingly, the object 295 has a relatively high height dimension in its three-dimensional structure. There is also no perspective distortion in the telecentric optics because the optical axis of the telecentric optics always remains parallel to the beam. Therefore, when the object is far from the camera system 240, it appears the same size from every viewpoint, and not smaller. Because there is no distortion in the case of the telecentric optics, the edges of 3D objects can be identified better and more accurately, making 3D image processing easier and particularly robust.

[0119] The focal point (distance) of the optical device 250 is selected such that (i) the first focal plane F1 associated with the first image sensor 242 is at... Figure 2 The center is located above object 295, and (ii) the second focal plane F2 associated with the second image sensor 244 is in Figure 2 The object is located below the object 295. This results in blurry images of the object 295 being generated on the two image sensors 242 and 244, respectively. These two images are processed by the image processing unit 260, which calculates a 3D height map of the object 295 using "optical interpolation" based on first image information from the first image and second image information from the second image.

[0120] According to the embodiment shown herein, the optical inspection system 220 also has another (optional) irradiation device 232, which uses another irradiation light 232a to irradiate the object 295 at an oblique angle along another irradiation path.

[0121] According to the embodiment shown herein, the other illumination light 232a has a different color than illumination light 230a. As described above, by appropriately combining illumination light colors according to the corresponding optical conditions, error-free inspection results can be achieved. Here, the optical conditions can be determined in particular by the optical properties of the object surface, such as color and reflectivity (glossy or matte).

[0122] Figure 3 An optical inspection system 320 according to another embodiment of the present invention is shown. The inspection system 320 is... Figure 2 The optical inspection system 220 differs only in that (i) a second beam splitter is absent, and (ii) a different camera system 340 is used. (As from...) Figure 3As can be seen, the camera system 340 has only one image sensor 342. In order to still produce two images of object 295 with different levels of sharpness, the single image sensor 342 can be moved relative to the optics 250. This mobility is... Figure 3 The vertical double arrow is represented by a dashed line.

[0123] If the sole image sensor 342 is in the upper position, it is spaced apart from the optics 250 by a distance Z1. Here, an unclear first image of the object 295 can be captured along a relatively long first measurement path using the first measurement light 342a. When the sole image sensor 342 is in the lower position (here, the sole image sensor 342 is shown in dashed lines), it is spaced apart from the optics 250 by a distance Z2. Here, an unclear second image of the object 295 can be captured along a relatively short second measurement path using the second measurement light 344a.

[0124] Figure 4 An optical inspection system 420 according to another embodiment of the present invention is shown. The inspection system 420 is... Figure 3 The only difference in the optical inspection system 320 is that, in the camera system 440, two image sensors are optically connected front and back, instead of a single, movable image sensor along a straight optical measurement path. The first image sensor is located at the end of the straight optical measurement path. Figure 4 The second image sensor, indicated by reference numeral 442, is a partially transparent image sensor. This means that, in... Figure 4 The common measurement light 246 that shines from below onto the second transparent image sensor 444 is only partially "captured" by the image sensor 444.

[0125] Specifically, a portion of the common measurement light 246, in the form of a second measurement light 444a, from the second transparent image sensor 444 is used to generate a (blurred) second image. Another portion of the common measurement light 246, in the form of a first measurement light 442a, passes through the second transparent image sensor 444 and is used by the first image sensor 442 to generate a (blurred) first image.

[0126] Figure 5 An optical inspection system 520 according to another embodiment of the present invention is shown. The inspection system 520 is... Figure 4The optical inspection system 420 differs in that the camera system 540 (re-)has only a single image sensor 542 onto which all the measuring light 246 is directed. However, in order to generate two blurry images using the single (fixedly arranged) image sensor, and to transmit these two blurry images based on a "defocusing" technique used to calculate a 3D height map of the object 295, the optical inspection system 520 has an adaptive optics 550 (with a variable focus) instead of a fixed-focus optics. A (blurry) first image can then be captured in a first focus setting of the adaptive optics, and a (blurry) second image can be captured in a second focus setting of the adaptive optics.

[0127] It should be noted that the term "having" does not exclude other elements, and the numeral "a" does not exclude a plurality. Furthermore, elements described in different embodiments may be combined. It should also be noted that the reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

1. A manufacturing machine (100) for a production line of electronic components, said manufacturing machine (100) comprising: Rack (102); Manufacturing tool (130), said manufacturing tool being directly or indirectly movably or spatially fixedly mounted on said frame (102); and Optical inspection systems (120a, 120b, 220, 320, 420, 520), wherein the optical inspection systems are directly or indirectly movably or spatially fixedly mounted on the frame (102), wherein, The optical inspection system (120a, 120b, 220, 320, 420, 520) includes an illumination device (230) for illuminating an object (295) with an illumination light (230a), a camera system (240, 340, 440, 540) for (i) capturing a first image of the illuminated object (295) with a first measuring light (242a, 342a, 442a) and (ii) capturing a second image of the illuminated object with a second measuring light (244a, 344a, 444a), optical components (250, 550), and an image processing unit (260) subsequently mounted on the camera system (240, 340, 440, 540). The illuminating device (230), the optical devices (250, 550) and / or the camera system (240, 340, 440, 540) are arranged in the optical paths of the illumination light (230a), the first measuring light (242a, 342a, 442a) and / or the second measuring light (244a, 344a, 444a), wherein the illumination device (230), the optical devices (250, 550) and / or the camera system (240, 340, 440, 540) are configured and arranged such that the first image has a first blur and the second image has a second blur different from the first blur, and wherein the image processing unit (260) is configured to determine a three-dimensional height map of at least a portion of the object (295) based on the first image and the second image.

2. The manufacturing machine (100) according to claim 1, wherein, The first depth of field range of the optical imaging of the first image associated with the first ambiguity and the second depth of field range of the optical imaging of the second image associated with the second ambiguity do not overlap.

3. The manufacturing machine (100) according to claim 1, wherein, Along the propagation direction of the illumination light (230a), the first focal plane (F1) associated with the first image is located in front of the object plane of the object (295), and the second focal plane (F2) associated with the second image is located behind the object plane of the object (295).

4. The manufacturing machine (100) according to claim 1, wherein, The first ambiguity or the second ambiguity is at least approximately zero.

5. The manufacturing machine (100) according to claim 4, wherein, The illumination light (230a) is directed onto the object (295) along the z-axis, and the first measuring light (242a, 342a, 442a) and the second measuring light (244a, 344a, 444a) leave the object (295) along the z-axis.

6. The manufacturing machine (100) according to claim 5, wherein, The optical inspection system (120a, 120b, 220, 320, 420, 520) has a first beam splitter (262) that spatially separates a portion of the illumination path of the illumination light (230a) from a portion of the measurement path of the measurement light (246).

7. The manufacturing machine (100) according to claim 6, wherein, At least one other illumination light (232a) provided to the object (295) is coupled in particular via reflection at the first beam splitter (262), wherein the other illumination light (232a) illuminates the object (295) at a different angle than the illumination light (230a).

8. The manufacturing machine (100) according to claim 7, wherein, The illumination light (230a) and the other illumination light (232a) have different colors.

9. The manufacturing machine according to claim 1, wherein, The optical devices (250, 550) have at least almost no chromatic aberration.

10. The manufacturing machine (100) according to claim 1, wherein, The optical devices (250, 550) are telecentric.

11. The manufacturing machine (100) according to claim 1, wherein, The camera system is configured to capture a third image of the illuminated object using a third measuring light, wherein the illumination device, the optics and the camera system are configured and arranged such that the third image has a third ambiguity that is different from both the first ambiguity and the second ambiguity, and wherein the image processing unit is configured to further determine a three-dimensional (3D) height map based on the third image.

12. The manufacturing machine (100) according to claim 1, wherein, The manufacturing machine is an assembly machine (100), and wherein the manufacturing tool is an assembly head (130), the assembly head being configured for: (i) Pick up electronic components (192) from the component pick-up position (116) of the component supply mechanism (115). (ii) The picked-up component (192) is conveyed to the assembly area (110) of the assembly machine (100), where the component support (190) to be assembled is located, and (iii) The components delivered to the assembly area (110) are placed on the component carrier (190) at the pre-given component loading positions.

13. The manufacturing machine (100) according to claim 12, wherein, The camera system is spatially and directly or indirectly mounted on the assembly head.

14. The manufacturing machine (100) according to claim 12, wherein, The camera systems (240, 340, 440, 540) are spatially fixed and directly or indirectly mounted on the frame (102).

15. The manufacturing machine according to claim 1, wherein, The manufacturing machine is a solder paste printing machine.

16. The manufacturing machine (100) according to claim 1, wherein, The camera system has a first image sensor (242, 442) for capturing a first image and a second image sensor (244, 444) for capturing a second image, wherein the two image sensors (242, 442, 244, 444) are spatially fixedly arranged with respect to the optics (250) and / or with respect to the illumination device (230).

17. The manufacturing machine (100) according to claim 16, wherein, The optical inspection system (120a, 120b, 220) also has a second beam splitter (264) that spatially separates a portion of the first measurement light path of the first measurement light (242a) from a portion of the second measurement light path of the second measurement light (244a).

18. The manufacturing machine (100) according to claim 16, wherein, The first image sensor is a transparent image sensor (444) that detects the first measuring light (442a), and the second measuring light (444a) passes through the transparent image sensor (444) to be detected by the second image sensor (442).

19. The manufacturing machine (100) according to claim 1, wherein, The camera system has only one image sensor (342) that is spatially positioned about the object plane and / or about the optics (250) such that the first image can be captured at a first position of the single image sensor (342) and the second image can be captured at a second position of the single image sensor (342) different from the first position.

20. The manufacturing machine (100) according to claim 1, wherein, The camera system (540) has only one image sensor (542), which is spatially fixed about the object plane and / or about the optics (550), and wherein the optics (550) are adaptive in terms of focus, such that (i) In a first state with a first focal point, the first image can be captured by the single image sensor (542), and (ii) In the second state with a second focus, the second image can be captured by the single image sensor (542).

21. The manufacturing machine (100) according to claim 1, wherein, The optical device has chromatic aberration, and the illumination light has at least a first illumination color and a second illumination color, wherein the first measuring light is associated with the first illumination color, and the second measuring light is associated with the second illumination color.

22. The manufacturing machine (100) according to claim 21, wherein (i) The first image can be captured in a first operating state of the optical inspection system, and the object is illuminated with the first illumination color in the first operating state, wherein... (ii) The second image can be captured in the second operating state of the optical inspection system, and the object is illuminated with the second illumination color in the second operating state.

23. The manufacturing machine (100) according to claim 21, wherein, The camera system includes a spectral resolution image sensor configured to extract the first image and the second image from a whole image of an illuminated object taken with the first illumination color and the second illumination color.

Images