Manufacturing machine for electronic assembly production lines equipped with "Focus Depth Estimation Method" optical inspection system

Abstract

In electronic assembly manufacturing lines, this enables easily implemented and reliable 3D inspection of solder paste deposits and components to be mounted and / or already mounted. [Solution] The optical inspection system includes an illumination device (230) for illuminating an object (295), a camera system (240) for capturing a first image of the object illuminated with a first measuring light (242a) and a second image of the object illuminated with a second measuring light (244a), an optical system (250) arranged in the optical paths of the illumination light, the first measuring light and / or the second measuring light, and an image processing unit (260) located downstream of the camera system. The illumination device and camera system are configured and arranged such that the first image has a first blur and the second image has a second blur, and are configured to determine a three-dimensional elevation map relating to at least a portion of the object based on the first and second images.

Description

Technical Field

[0001] The present invention generally relates to the technical field of automated electronic device manufacturing. In particular, the present invention relates to a manufacturing machine equipped with an optical inspection system for capturing and processing images of images, particularly solder paste deposits, components, and / or component carriers.

Background Art

[0002] An assembly having a plurality of discrete electronic components is typically constructed on a component carrier, such as a printed circuit board. In the field of mass production of electronic devices, this is generally done using a special manufacturing line having a transport device for the component carrier and a plurality of manufacturing machines arranged along it. The manufacturing machines on the manufacturing line for electronic device manufacturing include a solder paste printer, typically a plurality of mounting machines and soldering machines arranged in sequence, all of which are arranged along the transport device.

[0003] In a solder paste printer, a high-viscosity solder paste is applied to the component carrier in the form of individual solder paste deposits. This is generally done using screen printing.

[0004] In a mounting machine, electronic components are placed on a component carrier. For this purpose, a typical mounting machine has a mounting head that (i) picks up the component to be mounted from the component pickup position of the component supply device, (ii) transports the picked-up component to the mounting area of the mounting machine where there is a component carrier to be mounted respectively, and (iii) places the component transferred to the mounting area at a predetermined component mounting position on the component carrier or the associated solder paste deposit. To pick up the component, a typical mounting head uses one or more component holding devices configured, for example, as a vacuum gripper.

[0005] In a soldering machine, the solder paste deposit is melted, and after it cools, the mounted components are soldered to the electrical component connection surface formed on the component carrier in a way that is permanent and conductive.

[0006] To ensure a reliable soldering process, each solder paste depot must contain a predetermined amount of solder paste. If the amount of solder paste in a solder paste depot is too small, the corresponding solder joint may be mechanically unstable and / or, in particular, have insufficient conductivity. If the amount of solder paste in a solder paste depot is too large, a short circuit may occur between adjacent component connection surfaces when melted in the soldering machine.

[0007] Patent Document 1 discloses an image processing system for detecting the three-dimensional (3D) structure of a solder paste deposit applied on a component carrier. In this system, based on the principle of "photometric stereo," such a deposit is illuminated from three different lighting angles, and an image is taken from each angle, with each image having a separate intensity distribution depending on the 3D shape of the deposit.

[0008] By combining and evaluating three images, it becomes possible to determine the 3D structure of each solder paste deposit, and consequently, its volume or the amount of solder paste it contains.

[0009] To ensure reliable and accurate mounting, it is necessary to optically capture the component held by the component holder using a camera and determine the precise spatial position of the held component relative to the (tip) of the component holder through appropriate image processing. If there is a deviation from the relative target position, it can be detected and corrected during the mounting process by appropriate positioning of the mounting head and / or rotation of the component holder around its longitudinal axis. Furthermore, it is possible to detect whether the component is held by the component holder in the correct orientation relative to the main face or in the wrong orientation relative to the smaller side (so-called upright position). Furthermore, it is possible to detect when the component is held in an oblique or inclined spatial orientation. Furthermore, it is possible to detect when the held component has a mechanical defect. Components held in the wrong orientation and defective components cannot be further processed and generally need to be removed from the mounting process.

[0010] However, for reliable and accurate implementation, it is also necessary to determine the precise position of each component carrier on which the components are to be mounted. Only then can it be guaranteed that each component is accurately placed on the component carrier at its designated mounting position. Typically, the position of a component carrier is determined by optically measuring at least one marking present on the component carrier.

[0011] Capturing not only two-dimensional (2D) images but also three-dimensional (3D) images is desirable for the optical inspection processes of solder paste depots, components, and component carriers described above, and is essential for a fast, accurate, and reliable manufacturing process. In this context, 3D images are also referred to as elevation maps, and the corresponding spatial 3D structures are also referred to as elevation features.

[0012] In the field of packaging technology, various techniques are known for optical 3D inspection. For example, Patent Document 2 describes a method and apparatus for determining the orientation of a component having curved connection contacts, which is held by a component holding device, based on characteristic optical reflections. Characteristic optical reflections occur when illumination light strikes various partial cross-sections of the curved connection contacts at oblique illumination angles.

[0013] Patent Document 3 discloses a mounting machine having an image processing system configured to inspect the mounting contents of electronic components for an electronic assembly that is at least partially mounted on a component carrier. In this inspection, a three-dimensional reference height profile of a reference mounting contents of electronic components arranged in a reference assembly is used. The three-dimensional height profile of the component in the mounting contents is detected, and the detected height profile is compared with the reference height profile. If at least a portion of the height profile differs from the corresponding portion of the reference height profile, the mounting contents are identified as an error. Otherwise, the mounting contents are identified as not an error. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] German Patent Application Publication No. 102013216196 Specification [Patent Document 2] German Patent Application Publication No. 102018102288 [Patent Document 3] German Patent Application Publication No. 102016122494 Specification [Overview of the project] [Problems that the invention aims to solve]

[0015] The object of the present invention is to enable easily achievable and reliable 3D inspection of (i) solder paste deposits and (ii) components to be mounted and / or already mounted in an electronic assembly manufacturing line.

[0016] This problem is solved by the subject matter of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims. [Means for solving the problem]

[0017] According to a first aspect of the present invention, a manufacturing machine for an electronic assembly production line is described. The manufacturing machine includes (a) a chassis, (b) manufacturing tools that are movable or fixedly mounted directly or indirectly to the chassis, and (c) an optical inspection system that is movable or fixedly mounted directly or indirectly to the chassis. The optical inspection system includes (c1) an illumination device for illuminating an object with illumination light, (c2) a camera system for capturing (i) a (two-dimensional) first image of the object illuminated with a first measuring light, and (ii) a (two-dimensional) second image of the object illuminated with a second measuring light, (c3) an optical system arranged in the optical paths of the illumination light, the first measuring light, and / or the second measuring light, and (c4) an image processing unit located downstream of the camera system. The illumination device, the optical system, 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) elevation map of at least a portion of the object based on the first and second images.

[0018] The manufacturing machinery described is based on the recognition that, in the field of electronic equipment manufacturing, particularly in manufacturing machinery for production lines for manufacturing electronic assemblies, particularly excellent optical inspection results can be easily and effectively obtained by using the already known "depth of focus estimation method."

[0019] Simply put, the "depth of focus estimation" technique described here creates a 3D elevation map from two images taken at different Z distances in the field of electronic assembly manufacturing.

[0020] For two images, by appropriately selecting the sharpness setting, each object pixel can have a characteristic blur through its individual distance from the respective focal plane in the two images. From this characteristic blur, the altitude position of each object pixel can be calculated.

[0021] The "depth of focus blur estimation method" technology can be implemented using an apparatus in various embodiments or methods, as will be described in more detail below. However, common to all embodiments described below is that each "depth of focus blur estimation method" optical inspection system can be realized with a structurally simple and particularly compact design. Therefore, the above-described optical inspection system can also be used in a very narrow space area of the above-described manufacturing machine.

[0022] Furthermore, the above-described optical inspection system can be realized using at least no moving parts or using a small number of mechanically movable parts. This simplifies manufacturing and increases the mechanical durability of the inspection system. Furthermore, there is no need to move the object between taking the first image and taking the second image. This makes it possible to take two different clear (blurred) images within a very short time, and in some cases, even to take them simultaneously. Therefore, the optical 3D inspection process is speeded up compared to known 3D methods, thereby providing a time advantage, which is particularly advantageous due to the cost pressure common in electronic device manufacturing.

[0023] Furthermore, an accurate image reconstruction of the object in focus can be calculated from the two images. This is because artifacts can be removed, in contrast to image reconstruction using only one image. This improves the accuracy and robustness in detecting marks, patterns, and barcodes, particularly when the object in question is not exactly positioned at the focus of the optical imaging, compared to simple and still frequently used 2D capture.

[0024] The object described above may be any arbitrary object that should be optically detected in 3D within the manufacturing scope of an electronic assembly.

[0025] In particular, as already suggested, the object can be a marking formed on a solder paste depot, a component, or a component carrier.

[0026] The manufacturing tool described above can be any kind of tool configured to perform at least one manufacturing step or to be involved in at least such steps in the manufacture or production of an electronic assembly built on a component carrier. Examples of manufacturing tools include the mounting head of a mounter, the squeegee device of a solder paste printer, etc.

[0027] The image processing unit described above may be incorporated within the casing of an optical inspection system, which is not described in detail, or may be attached to the casing. Alternatively, the image processing unit may be incorporated as a processor within a larger computing unit. Such a larger computing unit may be, for example, a master computer that controls and / or adjusts at least a part of the operation of a manufacturing machine. Further, the image processing unit may be realized in the form of software and / or in a hybrid form combining software and hardware components, not in a concrete form.

[0028] According to an embodiment of the present invention, there is no spatial overlap between the first depth of focus region assigned to the first blur of the optical imaging of the first image and the second depth of focus region assigned to the second blur of the optical imaging of the second image.

[0029] Due to the spatial difference between the two depth of focus regions described above, an accurate 3D height map can be determined even in the case of relatively tall objects where at least some object points of the object have a relatively large height difference from each other.

[0030] According to a further embodiment of the present invention, along the propagation direction of the illumination light, the first focal plane assigned to the first image is located in front of the objective plane of the object. The second focal plane assigned to the second image is located behind the objective plane of the object. This clearly means that with respect to the object, or more precisely the objective plane of the optical inspection system, the two focal planes described above are on different sides. In other words, the object is located between the two focal planes.

[0031] The spatial arrangement of the objective planes with respect to the two focal planes described above means that determining the 3D elevation map involves interpolation between the first image information of the first image and the second image information of the second image. Such interpolation favorably enables a particularly accurate and error-resistant determination of the 3D elevation map.

[0032] According to a further embodiment of the present invention, either the first or second blur is at least nearly zero. This means that the first focal plane assigned to the first image, or alternatively the second focal plane assigned to the second image, coincides at least approximately with the objective plane of the object. In other words, one of the two images is a sharp image. This has the advantage that, in addition to the identified 3D elevation map, a two-dimensional (2D) image is also automatically available by capturing a sharp image. In the optical inspection described above, the 2D image information of the sharp 2D image can be combined with the 3D elevation map information of the determined 3D elevation map. This makes it possible to optically recognize features of the object that cannot be recognized in 3D inspection without using 2D image information.

[0033] The evaluation combining the 3D elevation map information and 2D image information described herein can be used, for example, to ensure the recognition of low-contrast characters that are normally almost invisible to the naked eye, and / or characters on reflective surfaces.

[0034] In this regard, it should be noted that additional 2D images can be acquired regardless of time. A third image acquisition is not necessary beyond the two images required to determine the 3D elevation map.

[0035] According to a further embodiment of the present invention, the illumination light strikes the object along the z-axis, and the first and second measurement lights move away from the object along this z-axis (in opposite directions).

[0036] In this process, the first and second measurement beams are generated by the illumination light being at least partially reflected or (back)scattered by the surface of the object. Immediately after this reflection or scattering, the first and second measurement beams may be indistinguishable from each other. Only then do the optical paths of the two "measurement beams" split into two spatially separated optical path portions, with the first image being captured in the first optical path portion and the second image being captured in the second optical path portion.

[0037] The coaxial propagation of illumination and measurement light, implemented along a predetermined z-direction or z-axis as described here, has the significant advantage of enabling the creation of a three-dimensional elevation map without the influence of shading. This is true when the z-direction is perpendicular to the objective plane.

[0038] In other 3D inspection methods (e.g., triangulation or photometric stereo), the angle of illumination light and the angle of measurement light are different, so shaded areas can always exist due to the edges of the object causing obstruction. In such shaded areas, the 3D elevation map cannot be calculated accurately or at all. In contrast, the “focus blur depth estimation” technique described in this embodiment, to put it simply, both images are taken “from the front,” and the object is preferably illuminated from the front as well. This allows for the calculation of an accurate and shade-free elevation map even in the edge regions of tall objects, so that, for example, small parts near tall parts can be fully visible in the determined elevation map. For a qualitatively accurate elevation map, a telecentric camera system or a camera system with a telecentric optical system may be used on the object side.

[0039] According to a further embodiment of the present invention, the optical inspection system has a first beam splitter that spatially separates a portion of the illumination path of the illumination light from a portion of the measurement path of the measurement light.

[0040] The first beam splitter may be a semi-transparent or partially transparent mirror, or a beam splitter cube. Preferably, illumination light is reflected by the first beam splitter, and measurement light passes through the first beam splitter with a slight parallel offset caused by refraction within the first beam splitter.

[0041] According to a further embodiment of the present invention, at least one additional illumination beam is coupled to the object by reflection at the first beam splitter, and this additional illumination beam illuminates the object at a different angle from the aforementioned illumination beam.

[0042] As described above, according to this embodiment, the illumination light is directed vertically from above along the z-direction, which is perpendicular to the object plane on which the object is located. Therefore, the additional illumination light strikes the object at an oblique angle. In this embodiment, at most, shadows may be produced by the additional illumination light depending on the "inclination" at other angles. Since both the illumination light and the measurement light strike or move away from the object along the z-direction, no shadows are processed.

[0043] This specification describes various directions or angles of illumination light with respect to the z-direction. This means that the illumination light is so-called 0° illumination. This further illumination light can strike the object at angles of, for example, at least about 30°, 60°, 70°, or 80°.

[0044] In addition to the first additional illumination light, it is desirable to have a second additional illumination light, and possibly a third additional illumination light, or even a fourth additional illumination light.

[0045] Depending on the number of additional illumination lights, each illumination angle may include any selection from the angles of at least approximately 30°, 60°, 70°, or 80° as described above.

[0046] Additional oblique lighting, including at least one additional light source, can, advantageously, enable particularly accurate determination of 3D elevation maps. This is especially true for objects with "visually problematic surfaces," such as glossy surfaces or surfaces with visually dull structural features on a non-glossy surface.

[0047] According to a further embodiment of the present invention, the illumination light and the further illumination light have different light colors.

[0048] By appropriately combining the light color or spectral distribution of various illumination sources, error-resistant inspection results can be obtained according to each optical condition. In this case, the optical conditions are determined in particular by the optical properties of the object's surface, such as color and reflectivity (glossy or matte). The same applies, in some cases (in 2D image capture), to recognized markings, especially when the markings have low contrast against the rest of the object's surface.

[0049] According to further embodiments of the present invention, the optical system has at least virtually no chromatic aberration.

[0050] If chromatic aberration is absent (for example, if the imaging optical system includes a chromatic aberration correction lens), it can be advantageously ensured that each object point is imaged at an image point with a small scattering circle. This is particularly true in illumination scenarios with different illumination colors and is especially important when the object points are relatively far from the focal plane of the measurement light.

[0051] According to a further embodiment of the present invention, the optical system is telecentric.

[0052] A telecentric optical system may be configured to have telecentricity on both the object side and / or the image side. In particular, in an image-side telecentric imaging optical system, the object point is located at the same position in both images. If the object point is presented at a different z-distance (distance from the focal plane of the camera system on the object side), the image scale does not change. This is advantageous because the distance between high-altitude and low-altitude features of the object is the same at all z-distances. Therefore, since only perpendicular measurement rays contribute to imaging, shading of small parts near the edges of high-altitude objects cannot occur.

[0053] According to a further embodiment of the present invention, the camera system is configured to capture a third (two-dimensional) image of an illuminated object using a third measuring light, the illumination device, optical system and / or camera system are configured and arranged such that the third image has a third blur that is different from both the first and second blurs, and the image processing unit is configured to determine five further three-dimensional (3D) elevation maps based on the third image.

[0054] By considering two or more images from different distances, more optical information can be incorporated into the determination or calculation of the altitude map. This not only improves inspection accuracy but also expands the altitude measurement range, especially by taking additional images. However, for many applications, processing information from two images by an image processing unit is sufficient; therefore, this specification mainly describes the determination of a 3D altitude map from only two images. In this case, all relevant descriptions also apply when multiple images are taken from different focal lengths.

[0055] According to a further embodiment of the present invention, the manufacturing machine is a mounting machine. Furthermore, the manufacturing tool is a mounting head, which is configured to (i) pick up an electronic component from a component pickup position of a component supply device, (ii) transport the picked-up component to the mounting area of ​​the mounting machine where a component carrier to be mounted is located, and (iii) place the component transported to the mounting area onto the component carrier at a predetermined component mounting position.

[0056] The manufacturing machine configured as described above is based on the recognition that the aforementioned "focus blur depth estimation method" technology can be applied particularly advantageously and beneficially in the field of packaging technology.

[0057] For example, tilted parts can be detected with particular reliability. In particular, it can detect (undesirable) tilt angles relative to the longitudinal axis of part holding devices, such as vacuum grippers. That is, the tilt angle can be precisely determined from the difference in height values ​​of two different edges of the part. If this tilt angle exceeds a certain tolerance, the tilted part should be removed from the assembly process to prevent assembly errors.

[0058] Furthermore, inverted parts with curved connection contacts (so-called gull-wing parts) can also be accurately and reliably identified. This helps prevent mounting errors. In addition, wear inspections can be performed on the tips of part holders, particularly the front end faces of vacuum grippers. Such wear inspections can be used to promptly replace defective or worn part holders.

[0059] According to a further embodiment of the present invention, the camera system is fixedly mounted directly or indirectly to the mounting head. This has the advantage that the "focus depth estimation" camera system also moves automatically as the mounting head moves. Therefore, for example, it is possible to inspect the component carrier to be mounted either across the surface or at various positions on the component carrier, and a dedicated positioning system for the camera system is not required.

[0060] Furthermore, if the structure of the mounting machine is appropriate, the components to be mounted can be optically inspected in 3D with high precision even before pickup by the mounting head or by the component holding device of the mounting head. Also, the volume and / or shape of the solder paste deposit at the placement location can be examined before the components are placed by the mounting head. Furthermore, after mounting, at least a portion of the mounted contents can be optically inspected in 3D. In this context, the mounted contents are understood to be the totality consisting of multiple already mounted electronic components.

[0061] According to a further embodiment of the present invention, the camera system is fixedly mounted to the chassis, either directly or indirectly. This allows for easy and reliable 3D inspection of parts picked up by the mounting head or the part holding device of the mounting head using the “focus depth estimation method” technique described herein.

[0062] According to a further embodiment of the present invention, the manufacturing machine is a solder paste printing machine. This manufacturing machine, configured as a solder paste printing machine, is based on the recognition that the “focus blur depth estimation method” technique described above can be applied particularly advantageously and beneficially to printing on printed circuit boards or component carriers. Thus, by known methods using printing methods, particularly using the silkscreen method, it is possible to inspect the volume and / or 3D shape of the solder paste deposit with respect to the quality of the applied solder paste before preparing the component carrier, and defective component carriers with printed solder paste are not supplied to the mounting process at all.

[0063] According to a further embodiment of the present 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, both image sensors being fixedly positioned relative to the optical system and / or illumination device. This has the advantage of eliminating the need for moving parts in the optical inspection system to capture two images, and furthermore, allowing images to be captured simultaneously without loss of time.

[0064] Different blurs in two images can be easily created, for example, by placing two image sensors, which could be conventional CCD or CMOS camera chips, at different distances relative to the optical system. Simply put, the two image sensors are positioned at different focal lengths relative to the object.

[0065] According to a further embodiment of the present 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.

[0066] In this context, spatial separation can be understood as meaning that the two measurement beams, namely the first measurement beam and the second measurement beam, first move away from the object along a common measurement beam path (in this case, it is preferable that the propagation directions of the two measurement beams in the common measurement beam path are antiparallel to the direction of at least some of the illumination light hitting the object). Next, the second beam splitter divides the common measurement beam path into the two measurement beam paths described above: the first measurement beam path and the second measurement beam path.

[0067] The second beam splitter may also be a semi-transparent or partially-transparent mirror, or a beam splitter cube. Preferably, one of the two measurement beams is reflected by the second beam splitter, and the other passes through the first beam splitter, and possibly a slight parallel offset occurs due to refraction at the first beam splitter.

[0068] By using a second beam splitter, it can be achieved, in a particularly easy and advantageous way, that the optical inspection system no longer requires any mechanically moving parts.

[0069] This allows the optical inspection system to have high mechanical robustness and / or high thermal stability for the reliable creation of accurate 3D elevation maps. Furthermore, the second beam splitter enables the simultaneous acquisition of two images, allowing for particularly rapid determination of the 3D elevation map.

[0070] According to a further embodiment of the present invention, the first image sensor is a transparent image sensor that detects a first measurement light, and the second measurement light passes through the first image sensor to be detected by the second image sensor.

[0071] To put it simply, the first image sensor uses the first measurement light to extract a portion of the total measurement light reflected from the object, allowing the remaining second measurement light to pass through and strike the second image sensor. This means that, along the propagation direction of the measurement light, the first measurement light is blocked by the first image sensor as part of the total measurement light.

[0072] By using a transparent image sensor, it is advantageous that the aforementioned additional component, the "second beam splitter," can be omitted, and yet two images can still be captured simultaneously.

[0073] According to a further embodiment of the present invention, the camera system has only a single image sensor, which is spatially positionable with respect to the object plane and / or optical system, so that a first image can be captured at a first position of the single image sensor, and a second image can be captured at a second position different from the first position of the single image sensor.

[0074] The aforementioned mobility or portability of the image sensor has the advantage, from an apparatus standpoint, that only a single image sensor is needed to capture two images, and therefore, an optical inspection system can be easily and, in particular, at low cost.

[0075] Regardless of how the spatial positioning of a single image sensor is achieved, the corresponding "depth of focus estimation" measurement process (over two image captures) can be carried out as follows: 1. A single image sensor is placed at a first position Z1. 2. Take the first image. 3. Place a single image sensor at the second position Z2. 4. Take a second picture.

[0076] As a result, two images are obtained, and a 3D elevation map can be determined from the relative degree of blur of the object pixels contained in these images.

[0077] According to a further embodiment of the present invention, the camera system has only a single image sensor fixedly positioned relative to the objective plane and / or the optical system. Furthermore, since the optical system is an adaptive optical system with respect to focus, (i) in a first state, a first image can be captured at a first focus of the single image sensor, and (ii) in a second state, a second image can be captured at a second focus of the single image sensor.

[0078] The use of adaptive optics has the advantage of reducing the number of components in the optical inspection system, which allows the "depth of focus estimation" technique to be easily and inexpensively incorporated into the aforementioned manufacturing machinery.

[0079] An adaptive optical system may, in principle, be any optical refraction and / or diffraction component whose focal length can be changed. Examples include so-called "liquid lenses" or motorized lenses. Liquid lenses have the advantage of being spatially compact and mechanically stable, as well as allowing the focal plane to be moved in a very short time, for example, within 10 milliseconds. In particular, by changing the aperture of the adaptive optical system, the sharpness of the image can be changed to obtain two different blurred images. Changing the aperture does not necessarily mean changing the diameter of a circular aperture. Changing the aperture can also be achieved by transmission at any position within a given aperture range.

[0080] Regardless of how the adaptive optical system is implemented, the "depth of focus estimation" measurement process (over two image acquisitions) can be carried out as follows: 1. Adjust the adaptive optical system so that the focal plane is at the first position Z1. 2. Take the first image. 3. Adjust the adaptive optical system so that the focal plane is at the second position Z2. 4. Take a second picture.

[0081] As a result, two images are obtained, and the 3D elevation map can be determined again from the relative degree of blur of the object pixels contained in these images.

[0082] According to a further embodiment of the present invention, the optical system has chromatic aberration, and the illumination light has at least a first illumination color and a second illumination color. Furthermore, the first measurement light is assigned to the first illumination color, and the second measurement light is assigned to the second illumination color.

[0083] This embodiment, which utilizes the physical optical properties of chromatic aberration, has the advantages of eliminating the need for any spatially moving parts and minimizing the number of optical components required to realize an optical inspection system. This ensures high robustness and high thermal stability of the optical inspection system.

[0084] In this context, "assigning" is understood to mean that the first image is primarily captured with the first lighting color, and the second image is primarily captured with the second lighting color. In this case, "color mixing" within a certain range is not excluded.

[0085] According to a further embodiment of the present invention, (i) a first image can be captured in a first operating state of the optical inspection system in which the object is illuminated with a first illumination color, and (ii) a second image can be captured in a second operating state of the optical inspection system in which the object is illuminated with a second illumination color.

[0086] To put it simply, in this embodiment, which is particularly easy to implement with respect to the camera system, a temporal separation is performed between the capture of two images. Specifically, this means that a first image is captured with a first illumination color, and then a second image is captured with a second illumination color. This results in two images, and a 3D elevation map is calculated from their relative sharpness according to the "depth of focus estimation method" technique.

[0087] According to a further embodiment of the present invention, the camera system has an image sensor with spectral resolution, which is configured to extract a first image and a second image from an overall image of an illuminated object captured in both a first and a second illumination color. This embodiment has the advantage over the above-described embodiment, which also relies on the effect of chromatic aberration, that only a single image needs to be captured. This advantage is obtained at the cost of the image sensor having at least some spectral resolution (which is now relatively inexpensive).

[0088] The spectral resolution of an image sensor is obtained, for example, by the high sensitivity of the pixels on the image sensor to color. For example, a first sensor pixel can preferentially detect a first illumination color, and a second sensor pixel can preferentially detect two illumination colors.

[0089] Further advantages and features of the present invention will become apparent from the following exemplary description relating to currently preferred embodiments. [Brief explanation of the drawing]

[0090] [Figure 1] This figure shows a manufacturing machine according to an embodiment of the present invention. [Figure 2] This figure shows an optical inspection system equipped with a camera system having a first image sensor and a second image sensor positioned at different distances from a beam splitter that splits a common measurement light into a first measurement light assigned to a first image sensor and a second measurement light assigned to a second image sensor. [Figure 3] This figure shows an optical inspection system equipped with a camera system having a single image sensor that is displaceable relative to the optical system. [Figure 4] This figure shows an optical inspection system equipped with a camera system having a first image sensor and a second image sensor, which is a partially transparent image sensor, arranged in succession along a common optical path for measurement. [Figure 5] This figure shows an optical inspection system equipped with a camera system having a single fixed image sensor and an adaptive optical system. [Modes for carrying out the invention]

[0091] In the following detailed description, it should be noted that features or components of different embodiments that are identical or at least functionally identical to corresponding features or components of other embodiments are given the same reference numeral as the corresponding identical or at least functionally identical feature or component, or have the same last two digits. To avoid unnecessary repetition, features or components already described based on the embodiments described above will no longer be mentioned in detail below.

[0092] Furthermore, it should be noted that the embodiments described below are merely a limited selection of possible variations of the present invention. In particular, the features of each embodiment can be combined in appropriate ways, and to those skilled in the art, the variations of the embodiments explicitly shown herein will be considered to clearly disclose a number of different embodiments.

[0093] Furthermore, as shown in the drawings, spatial terms such as "front" and "back," "up" and "down," and "left" and "right" are used to describe the relationship between one element and another. Therefore, spatial terms may also apply to orientations different from those shown in the drawings. However, it is obvious that all such spatial terms are related to the orientations shown in the drawings for the sake of simplicity and are not necessarily limited to them. This is because the devices, parts, etc., shown may be used in orientations different from those shown in the drawings.

[0094] Figure 1 schematically shows a manufacturing machine 100 configured as a mounting machine for mounting electronic components 192 onto a component carrier or printed circuit board 190. The manufacturing machine 100 has a chassis 102 as a fixed support structure.

[0095] A fixed support rail 104 is attached to or formed on the chassis 102, extending along the y-direction. A support arm 106 is attached to the fixed support rail 104, extending along the x-direction, and the support arm 106 can be moved along the y-direction by a drive motor (not shown). The corresponding direction of movement is indicated by a double arrow "Y". A mounting element 108 is attached to the support arm 106, and the mounting element 108 can be moved along the x-direction by a further drive motor (not shown). The corresponding direction of movement is indicated by a double arrow "X". The components of the support rail 104, support arm 106, and mounting element 108, together with two drive motors (not shown), constitute a so-called planar positioning system, which allows the manufacturing tool 130, configured as a mounting head, to be positioned in the xy-plane.

[0096] The component carrier 190 is mounted in the mounting area 110. Before mounting, the component carrier 190 to be mounted is transported to the mounting area 110 using a transport device 112, such as a conveyor belt. After the component 192 is mounted at least partially, the component carrier 190 is unloaded by the transport device 112. The corresponding transport directions are indicated by arrows T in Figure 1.

[0097] As is clear from Figure 1, the mounting head 130 is fixed to the mounting element 108. By appropriately controlling a drive motor (not shown), the mounting head 130 can be moved between the part pickup position 116 of the part supply system 114 and the mounting area 110. The control device 118 communicates with the mounting head 130 in particular via a data line 118a (shown by a dashed line) and a drive motor (not shown), and functions to ensure that mounting proceeds smoothly in a known manner. In this process, the mounting head 130 moves to the part pickup position 116 and picks up part 192 at the part pickup position 116. Next, the mounting head 130 moves to the mounting area 110 with the picked-up part 192, and in the mounting area 110, places part 192 on the prepared part carrier 190. After that, the mounting head 130 is returned to the part supply system 114 in an "empty" state, and part 192 is picked up again by the part supply system 114.

[0098] As is clear from Figure 1, the mounting machine 100 further has two optical inspection systems: a first optical inspection system 120a and a second optical inspection system 120b. However, it should be noted that the manufacturing machine according to the present invention may also have only a single optical inspection system.

[0099] The first optical inspection system 120a is fixedly mounted to the chassis 102 and, according to the embodiment shown herein, is used for 3D measurement of a component 192 picked up by the mounting head. For this purpose, the mounting head 130 is positioned on the optical inspection system 120a so that the picked-up component 192 is within the detection range of the optical inspection system 120a. This 3D component measurement can, for example, reliably detect whether a component is damaged. Furthermore, it can detect, for example, whether the picked-up electronic component 192 was picked up at an angle by the component holder, i.e., whether this results in a mounting error of the component 192. In addition, the precise angular position of the picked-up component 192 can be measured. When placing the component 192, deviations in angular position can be appropriately corrected by appropriately rotating the corresponding component holder, thereby ensuring that the component 192 is placed on the component carrier 190 at the correct angular position.

[0100] In the embodiment described herein, the second optical inspection system 120b is used to accurately measure markings provided on the upper surface of the component carrier 190 to be mounted. This allows for the detection of the precise spatial position of the component carrier 190 within the mounting area 110, and ensures that when positioning the mounting head 130, the component 192 is accurately placed at each specific target position on the component carrier 190. In the embodiment described herein, the second optical inspection system 120b is mounted on the mounting head 130 and moves with the mounting head 130 to measure the markings on the component carrier 190.

[0101] However, the second optical inspection system 120b can be used in a particularly advantageous manner to measure the so-called mounting contents, i.e., the mounted components, in 3D, at least after partial mounting. This allows for the detection of mounting errors if they occur, and, if necessary, the component carrier 190, at least partially mounted, to be excluded from further processing. Furthermore, the solder depot on which the connection of component 192 is placed can also be measured in 3D before mounting component 192. This allows for verification of whether the shape and / or volume of the solder depot are within the specified tolerance range.

[0102] Figure 2 shows an optical inspection system 220 according to a first embodiment of the present invention. The inspection system 220 has an illumination device 230 that irradiates an object 295 to be inspected with illumination light 230a. The illumination path of the illumination light 230a extends by reflecting off a first beam splitter 262. The illumination device 230 and the first beam splitter 262 are arranged and configured so that the illumination light 230a strikes the front of the object 295 from above.

[0103] As described above, the object 295 can be any, preferably a physical structure in three-dimensional space, that should be measured in 3D in the field of electronic equipment manufacturing, particularly in the field of mounting technology. This includes, for example, electronic components to be mounted, electronic components that have already been mounted, solder paste depots, markings on component carriers to be mounted, and so on.

[0104] The optical inspection system 220 further includes a camera system 240, which detects the object 250 from the front and above through the optical system 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. A second beam splitter 264 is positioned above the optical system 250, which splits a common measurement light 242c, emitted upward from the object 295 through the optical system 250 along a common measurement path, into two beams. These partial beams are referred to herein as the first measurement light 242a and the second measurement light 244a. The first measurement light 242a propagates along a first optical measurement path extending from the second beam splitter 264 (through) to the first image sensor 242. Correspondingly, the second measurement light 244a propagates along a second optical measurement path that extends from the second beam splitter 264 (reflected) to the second image sensor 244.

[0105] The two image sensors 242 and 244 are positioned at different distances from the second beam splitter 264. The corresponding distances are indicated as "Z1" and "Z2" in Figure 2.

[0106] According to the embodiment shown herein, the optical system 250 is a refractive optical system with a fixed focal length. The optical system 250 has multiple lenses 252, and two lenses 252 are shown as an example in Figure 2.

[0107] The optical system 250 is preferably a telecentric imaging optical system. A telecentric imaging optical system has the advantage of having a constant magnification, in particular, with respect to the principle of the "depth of focus estimation method" described herein.

[0108] In other words, this is maintained regardless of the distance of the object 295 to the imaging optical system 250. This means that even if the object 295 moves slightly, the image of the object 295 (on the two image sensors 242 and 244) maintains the same dimensions. Correspondingly, the same is true even if the object 295 has a relatively high three-dimensional structure. Furthermore, in a telecentric optical system, there is no perspective distortion because the optical axis of the telecentric optical system is always parallel to the light rays. That is, the object appears to be the same size from any angle, even if it is far away from the camera system 240, and it never appears smaller. Because there is no distortion in a telecentric optical system, it is possible to recognize the edges of 3D objects better and more accurately, which makes 3D image processing easier and especially more robust.

[0109] The focal point (distance) of the optical system 250 is selected such that (i) in Figure 2, the first focal plane F1 assigned to the first image sensor 242 is located above the object 295, and (ii) in Figure 2, the second focal plane F2 assigned to the second image sensor 244 is located below the object 295. As a result, blurred images of the object 295 are generated in each of the two image sensors 242 and 244. These two images are processed by the image processing unit 260, which calculates a 3D elevation map of the object 295 in the process of "optical interpolation" based on the first image information of the first image and the second image information of the second image.

[0110] According to the embodiment described herein, the optical inspection system 220 further has an (optional) additional illumination device 232, which illuminates the object 295 with additional illumination light 232a at an oblique angle along the additional illumination path.

[0111] In the embodiment shown here, the additional illumination light 232a has a different color compared to the illumination light 230a. As described above, by appropriately combining the colors of the illumination light according to each optical condition, it is possible to obtain inspection results that are resistant to errors. In this case, the optical conditions may be determined in particular by the optical properties of the surface of the object, such as color and reflectivity (glossy or matte).

[0112] Figure 3 shows an optical inspection system 320 according to a further embodiment of the present invention. The inspection system 320 differs from the optical inspection system 220 of Figure 2 in that (i) there is no second beam splitter and (ii) a different camera system 340 is used. As is evident from Figure 3, the camera system 340 has only a single image sensor 342. Nevertheless, the single image sensor 342 is displaceable relative to the optical system 250 in order to produce two images of the object 295 at different sharpness levels. This displaceability is indicated in Figure 3 by a dashed vertical double arrow.

[0113] When the single image sensor 342 is in the upper position, the image sensor 342 is at a distance Z1 from the optical system 250. Here, a first blurred image of the object 295 can be captured using the first measurement light 342a along a relatively long first measurement path. When the single image sensor 342 is in the lower position (here, the single image sensor 342 is shown by a dashed line), the image sensor 342 is at a distance Z2 from the optical system 250. Here, a second blurred image of the object 295 can be captured using the second measurement light 344a along a relatively short second measurement path.

[0114] Figure 4 shows an optical inspection system 420 according to a further embodiment of the present invention. The inspection system 420 differs from the optical inspection system 320 of Figure 3 only in that, in the camera system 440, instead of a single displaceable image sensor, two image sensors are optically connected one after the other along a linear optical measurement path. The first image sensor, located at the end of the linear optical measurement path, is indicated by reference numeral 442 in Figure 4. The second image sensor, indicated by reference numeral 444, is a partially transparent image sensor. This means that the common measurement light 246 that strikes the second transparent image sensor 444 from below in Figure 4 is only partially "captured" by the image sensor 444.

[0115] Specifically, a portion of the common measurement light 246 is used in the form of a second measurement light 442a by the second transparent image sensor 444 to generate a (blurred) second image. The other portion of the common measurement light 246 passes through the second transparent image sensor 444 in the form of a second measurement light 442a and is used by the first image sensor 442 to generate a (blurred) first image.

[0116] Figure 5 shows an optical inspection system 520 according to a further embodiment of the present invention. The inspection system 520 differs from the optical inspection system 420 of Figure 4 in that the camera system 540 (again) has only a single image sensor 542, and the entire measurement light 246 strikes the image sensor 542. Despite using a single (fixed-position) image sensor, the optical inspection system 520 has an adaptive optical system 550 (with variable focus) instead of an optical system with fixed focus, in order to generate two blurred images to be transmitted to calculate a 3D elevation map of the object 295 based on the “focus blur depth estimation method” technique. A first (blurred) image can be captured when the adaptive optical system is first focused, and a second (blurred) image can be captured when the adaptive optical system is second focused.

[0117] It should be noted that the term "having" does not exclude other elements, and "one" does not exclude multiple elements. Furthermore, elements described in relation to different embodiments can be combined. It should also be noted that reference numerals in the claims should not be interpreted as limiting the scope of protection of the claims. [Explanation of symbols]

[0118] 100 Manufacturing Machines / Plating Machines 102 Chassis 104 Fixed support rail 106 Movable support arm 108 movable mounting elements 110 Implementation Area 112 Conveying device 114 Parts supply system 115 Parts supply device 116 Component Pickup Location 118 Control device 118a Data Line 119 Manufacturing Tools / Mounting Heads 120a Optical inspection system for parts (fixed type) 120b Optical inspection system for printed circuit boards (mobile type) 190 Component Carrier / Printed Circuit Board 192 Electronic Components 220 Optical Inspection System 230 Lighting devices 230a Lighting / Lighting Path 232 Further lighting devices 232a Further illumination light / Further 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 system 252 lenses 262 First beam splitter 264 Second beam splitter 260 Image Processing Units 295 Object Z1 Distance to the first image sensor Distance to the second image sensor on the Z2 F1 First focal plane F2 Second focal plane 340 Camera System 342 Single 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) 444a First and second measurement light 540 Camera System 542 Single Image Sensor 550 Optical System (Adaptive) 552 Lens (removable) 552a Displacement motion

Claims

1. A manufacturing machine (100) for an electronic assembly manufacturing line, wherein the manufacturing machine (100) is Chassis (102); Manufacturing tools (119) that are attached to the chassis (102) directly or indirectly, in a movable or fixed manner; and, Optical inspection systems (120a, 120b, 220, 320, 420, 520) that are mounted directly or indirectly to the chassis (102) in a movable or fixed manner; Includes, The optical inspection system (120a, 120b, 220, 320, 420, 520) includes an illumination device (230) for illuminating an object (295) with illumination light (230a), a camera system (240, 340, 440, 540) for capturing (i) a first image of the object (295) illuminated using first measurement light (242a, 342a, 442a), and (ii) a second image of the object illuminated using second measurement light (244a, 344a, 444a), and is arranged in the optical path of the illumination light (230a), the first measurement light (242a, 342a, 442a), and / or the second measurement light (244a, 344a, 444a). A manufacturing machine (100) having an optical system (250, 550) and an image processing unit (260) located downstream of the camera system (240, 340, 440, 540), wherein the illumination device (230), the optical system (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 the image processing unit (260) is configured to determine a three-dimensional elevation map relating to 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 region assigned to the first blur of the optical image of the first image and the second depth of field region assigned to the second blur of the optical image of the second image 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) assigned to the first image is located in front of the objective plane of the object (295), and the second focal plane (F2) assigned to the second image is located behind the objective plane of the object (295).

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

5. The manufacturing machine (100) according to claim 4, wherein the illumination light (230a) strikes the object (295) along the z axis, and the first measuring light (242a, 342a, 442a) and the second measuring light (244a, 344a, 444a) move away from 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. In particular, the manufacturing machine (100) according to claim 6, wherein at least one further illumination light (232a) is coupled to the object (295) through reflection at the first beam splitter (262), and the further illumination light (232a) irradiates 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 further illumination light (232a) have different light colors.

9. The manufacturing machine according to claim 1, wherein the optical system (250, 550) has at least substantially no chromatic aberration.

10. The manufacturing machine (100) according to claim 1, wherein the optical system (250, 550) is a telecentric optical system.

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, the illumination device, the optical system and / or the camera system are configured and arranged such that the third image has a third blur that is different from both the first blur and the second blur, and the image processing unit is further configured to determine a three-dimensional (3D) elevation map based on the third image.

12. The manufacturing machine is a mounting machine (100), the manufacturing tool is a mounting head (119), and the mounting head (119) is (i) Pick up an electronic component (192) from the component pickup position (116) of the component supply device (115), (ii) The picked-up component (192) is transported to the mounting area (110) of the mounting machine (100) where the component carrier (190) to be mounted is located, and (iii) The components transported to the mounting area (110) are placed on the component carrier (190) at predetermined component mounting positions. A manufacturing machine (100) according to claim 1, configured as described above.

13. The manufacturing machine (100) according to claim 12, wherein the camera system is fixedly attached to the mounting head directly or indirectly.

14. The manufacturing machine (100) according to claim 12, wherein the camera system (240, 340, 440, 540) is directly or indirectly fixed and attached to the chassis (102).

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

16. The manufacturing machine (100) according to claim 1, wherein the camera system comprises a first image sensor (242, 442) for capturing the first image and a second image sensor (244, 444) for capturing the second image, and the two image sensors (242, 442; 244, 444) are fixedly positioned relative to the optical system (250) and / or the illumination device (230).

17. The manufacturing machine (100) according to claim 16, wherein the optical inspection system (120a, 120b, 220) further includes a second beam splitter (264) that spatially separates a portion of the first measurement path of the first measurement light (242a) from a portion of the second measurement 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 a first measurement light (444a), and the second measurement light (442a) passes through the transparent image sensor (444) in order to be detected by the second image sensor (442).

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

20. The camera system (540) has only a single image sensor (542), the image sensor (542) is fixedly positioned with respect to the objective plane and / or the optical system (550), and the optical system (550) is an adaptive optical system (550) with respect to the focal point, thereby, (i) In the first state, the first image can be captured at the first focal point by a single image sensor (542), (ii) The manufacturing machine (100) according to claim 1, wherein in the second state, the second image can be captured at a second focal point by a single image sensor (542).

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

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

23. The manufacturing machine (100) according to claim 21, wherein the camera system has an image sensor having spectral resolution, and the image sensor is configured to extract a first image and a second image from an overall image of an illuminated object captured in both the first illumination color and the second illumination color.

Images