DE102020113002B3 - Determining the accuracy of a placement machine when a test component is used multiple times - Google Patents

Abstract

A method for determining the placement accuracy of a placement machine (100) and a placement machine are described. The method comprises (a) introducing a reference plate (280) into a placement area of the placement machine, the reference plate having a plurality of reference markings (282); (b) picking up a test component (290) from a placement head (130); (c) placing the gripped test component at a test placement position on the reference plate using the placement head; (d) determining an actual position of the placed test component taking into account the position of at least one reference marking by means of a camera and an evaluation unit (160) connected downstream of the camera; (e) renewed picking up of the placed test component by the placement head; (f) Repositioning the newly picked up test component, now at a further test placement position, on the reference plate using the placement head; (g) again determining, now a further actual position of the newly placed test component, taking into account the position of at least one further reference marking by means of the camera and the evaluation unit; and (h) determining the placement accuracy of the placement machine based on a deviation between (i) the determined actual position and (ii) a target position for the test placement position and a further deviation between (i) the further actual position determined again and (ii) a further target position for the further test placement position.

Description

Technical area

The present invention relates generally to the technical field of placement technology. The present invention relates in particular to a method for determining the accuracy of an automatic placement machine and a placement machine.

Background of the invention

Placement machines have long been used in a known manner for the production of electronic assemblies on circuit carriers. In this case, the components are picked up by a component feeding device from a placement head of the placement machine and placed on a circuit carrier to be fitted, for example a printed circuit board. For this purpose, a conductor track structure with suitable component connection surfaces is formed on the surface of the circuit carrier. Components for such surface mounting are also referred to as SMD (Surface Mount Technology) components. Corresponding placement machines are referred to as SMD placement machines or SMD placement machines.

As a result of the increasing miniaturization of electronic assemblies with ever smaller components, in addition to the placement performance (= number of components fitted per time), the placement accuracy in particular is the central parameter of a placement machine. Only with a sufficiently high placement accuracy can it be guaranteed that the components are placed precisely on the circuit carrier so that the connection contacts of the components are correctly contacted with the corresponding component connection surfaces on the circuit carrier. In this way, for example, short circuits between adjacent component connection surfaces, caused by incorrect placement of a component, can be avoided.

It is known that the placement accuracy can change during the operation of a placement machine. For example, the placement accuracy can be impaired by thermal expansion effects of components of the placement machine, in particular of components of a positioning or portal system with which a placement head is moved. It is therefore necessary to check the placement accuracy of a placement machine from time to time and to precisely determine the actual actual positions of attached components in relation to corresponding target positions. Based on the results of such a determination, the placement machine can then be (re) calibrated or adjusted so that the placement accuracy is improved again when further components are placed.

1. (A) Anstelle eines realen Schaltungsträgers wird eine Glasplatte bestückt, auf welcher sich, räumlich hochgenau angeordnet, optisch erfassbare Mess-Markierungen befinden. Die Glasplatte ist auf ihrer Oberseite mit einer dünnen doppelseitigen Klebefolie (oder alternativ mit einem Film eines Sprühklebers) versehen. Die Bestückung der Glasplatte auf der klebrigen Oberseite erfolgt mit speziellen Test-Bauelementen. Die Test-Bauelemente sind hochpräzise Glas- oder Keramikbausteine, welche häufig ebenfalls hochgenaue optisch erfassbare Markierungen aufweisen. Nach dem Bestücken mit den Test-Bauelementen wird die bestückte Glasplatte in einer speziellen Messmaschine mit hoher Genauigkeit vermessen. Dabei werden die Positionen der klebrig anhaftenden Test-Bauelemente relativ zu den Mess-Markierungen der Glasplatte erfasst. Das Ergebnis wird von der Messmaschine als Messprotokoll ausgegebenen.
2. (B) Auch bei diesem Verfahren wird anstelle eines realen Schaltungsträgers eine Glasplatte verwendet, auf welcher sich zusätzlich zu den o.g. Mess-Markierungen flächig über die Glasplatte verteilt noch weitere Markierungen befinden. Auch diese Glasplatte wird mit einer doppelseitigen Klebefolie oder einer Schicht aus Sprühkleber versehen und anschließend mit einer Vielzahl von Test-Bauelementen bestückt. Im Gegensatz zu dem o.g. Verfahren (A) verbleibt die bestückte Glasplatte jedoch in der Bestückmaschine und wird dort mit einer Kamera vermessen, welche im normalen Bestückbetrieb für eine Positionsvermessung von in einen Bestückbereich eingebrachten Schaltungsträgern verwendet wird. Hierbei wird pro Test-Bauelement mit der Kamera lediglich eine relative Positionsvermessung zwischen (i) den Markierungen der Glasplatte und (ii) den Test-Bauteilen durchgeführt. Zur Vermessung wird die Kamera typischerweise mit dem gleichen Positionier- bzw. Portalsystem über die bestückte Glasplatte bewegt. Bei einer relativen Positionsvermessung gehen auf vorteilhafte Weise mögliche Fehler des Positioniersystems nicht in das Messergebnis ein. Ferner steht das Messergebnis direkt auf der betreffenden Bestückmaschine zur Verfügung.
3. (C) Bei diesem Verfahren wird die Glasplatte (mit Mess-Markierungen und weiteren Markierungen) auf die gleiche Weise und mit dem gleichen Test-Bauelementen bestückt wie bei dem Verfahren (B). Die Vermessung des Bestückinhaltes erfolgt jedoch wie bei dem Verfahren (A) in einer externen Messmaschine. Allerdings werden im Unterschied zu dem Verfahren (A) auch hier wie bei dem Verfahren (B) relative Positionsvermessungen zwischen jeweils einem bestückten Test-Bauelement und zumindest einer in der Nähe befindlichen Mess-Markierung oder weiteren Markierung durchgeführt.

Various methods (A), (B) and (C) are currently known for determining the placement accuracy:

1. (A) Instead of a real circuit carrier, a glass plate is fitted on which, spatially arranged with high precision, there are optically detectable measurement markings. The top of the glass plate is provided with a thin double-sided adhesive film (or alternatively with a film of a spray adhesive). The assembly of the glass plate on the sticky top is done with special test components. The test components are high-precision glass or ceramic components, which often also have high-precision, optically detectable markings. After the test components have been fitted, the fitted glass plate is measured with high accuracy in a special measuring machine. The positions of the sticky test components are recorded relative to the measurement markings on the glass plate. The result is output by the measuring machine as a measurement report.
2. (B) In this method, too, instead of a real circuit carrier, a glass plate is used on which, in addition to the above-mentioned measurement markings, there are further markings distributed over the glass plate. This glass plate is also provided with a double-sided adhesive film or a layer of spray adhesive and then equipped with a large number of test components. In contrast to the above-mentioned method (A), however, the assembled glass plate remains in the assembly machine and is measured there with a camera which is used in normal assembly operation to measure the position of circuit carriers introduced into an assembly area. For each test component, the camera only performs a relative position measurement between (i) the markings on the glass plate and (ii) the test components. For the measurement, the camera is typically moved over the fitted glass plate with the same positioning or portal system. In the case of a relative position measurement, possible errors in the positioning system are advantageously not included in the measurement result. Furthermore, the measurement result is available directly on the relevant placement machine.
3. (C) In this method, the glass plate (with measurement marks and other markings) is equipped in the same way and with the same test components as in method (B). The measurement of the However, as with method (A), the contents are placed in an external measuring machine. However, in contrast to method (A), here too, as in method (B), relative position measurements are carried out between in each case a fitted test component and at least one measurement marking or further marking located in the vicinity.

WO 2015/191833 A1 discloses a test device for determining the placement accuracy of a placement machine. The test device consists of a magnetic carrier which has an inner area that can be equipped as well as edge areas in which pockets are formed. A magnetic test component can be stored in each of the pockets, which is removed from a placement head for checking the placement accuracy of a placement machine and placed at a predetermined location on the area that can be placed. The placement accuracy is then checked by means of a camera. For this purpose, the actual position of the relevant test component is recorded relative to at least one of a plurality of reference markings that are located on the top of the carrier. In the case of an optically transparent carrier, the camera can be arranged below the carrier and capture the test component from below through the carrier.

The known methods described above for determining the placement accuracy all have the disadvantage that, depending on the size of the placement area in which the placement accuracy is to be determined, a more or less large number of high-quality and thus expensive test components is required. These test components must be kept available by the operator of a placement line.

Summary of the invention

The invention is based on the object of determining the placement accuracy of a placement machine in a simple manner and, in particular, in an effective manner with regard to the costs of high-precision test components.

This object is achieved by the subjects of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a method for determining the placement accuracy of a placement machine is described. The method comprises (a) introducing a reference plate into a placement area of the placement machine, the reference plate having a plurality of reference markings; (b) picking up a test component from a placement head; (c) placing the gripped test component at a test placement position on the reference plate using the placement head; (d) determining an actual position of the placed test component taking into account (the position) of at least one reference marking by means of a camera and an evaluation unit connected downstream of the camera; (e) another picking up of the placed test component by the placement head; (d) a renewed placement of the newly picked up test component, now at a further test placement position, on the reference plate using the placement head; (e) a renewed determination, now of a further actual position of the newly placed test component, taking into account (the position) of at least one further reference marking by means of the camera and the evaluation unit; and (f) determining the placement accuracy of the placement machine based on a deviation between (i) the determined actual position and (ii) a target position for the test placement position and a further deviation between (i) the newly determined further actual position Position and a further target position for the further test placement position.

The method described is based on the knowledge that, in contrast to known methods for determining the placement accuracy, it is not absolutely necessary to use several typically very expensive test components, all of which are available before an optical inspection or measurement of the test placement content can be equipped or placed in different positions on a reference plate. Rather, according to the invention, one and the same test component is placed multiple times and one after the other on the reference plate and optically measured before it is transferred to another further test placement position. The placement accuracy within a placement area of the placement machine covered by the reference plate is thus determined by means of a plurality of sequentially performed placement and measurement procedures, each of these procedures picking up the test component, placing the test component and optically detecting the respective actual (Placement) position includes.

The determination of the actual position and the renewed determination of the further actual position typically comprise two steps. A first step is optically capturing an image of the placed test component and the at least one reference mark by means of the camera. The second step is an image evaluation of the captured image by the evaluation unit using known methods of (digital) image processing. The first step must naturally take place when the test component is at the respective (further) placement position. The second step can be immediate the above-mentioned acquisition of the image take place or are only carried out later, if necessary, together with further image evaluations, which are used to determine the placement accuracy within the placement area of the placement machine.

The number of sequentially carried out placement and measuring procedures can in principle be as high as desired. In practice, this number will (a) depend on the size of the placement area to be measured and on the desired spatial resolution when determining the placement accuracy and / or (b) depend on the accuracy with which the placement accuracy of the placement machine is to be determined.

In the method described, the dwell time of the test component at its respective placement position is only very short. In addition, the optical measurement of the component takes place immediately after the test placement, so that the reference plate remains in a rest position within the placement area of the placement machine. It is therefore not necessary to fix the assembled test component by means of a double-sided adhesive film or a layer of spray adhesive. However, in certain cases it may still be necessary to temporarily fix the test component to the reference plate. However, only very small adhesive forces are required for this, so that laborious removal of test components and subsequent cleaning of the reference plate after carrying out the described method is advantageously not necessary or is very simple.

Another advantage of the described method for determining the placement accuracy is that the placement accuracy can in principle be determined as often as required and also during the production of a batch of electronic assemblies. In any case, a longer interruption of the placement operation is not necessary. It is only necessary, in the meantime, instead of a circuit carrier to be fitted, to bring the mentioned reference plate into the fitting area and to repeatedly place or place the test component at different test fitting positions on the reference plate.

In addition, the method described can be carried out in an advantageous manner without manual operator intervention by an operator. This facilitates a so-called remote control of the placement machine and possibly an entire production line for electronic assemblies, which production line also has other machines such as a circuit board printing machine and a reflow oven in addition to at least one placement machine.

The test component can be placed at a suitable location on the placement machine during the conventional placement operation. This location is preferably at a location from which it can be picked up by the placement head without manual operator intervention.

If, after determining the placement accuracy by means of the method according to the invention, a suitable calibration or “readjustment” of the placement machine is carried out, a consistently high placement precision can be ensured in an effective manner and in particular without major time delays.

According to an exemplary embodiment of the invention, the further test fitting position is different from the test fitting position. This can mean in particular that the test component is placed multiple times and one after the other on the reference plate at different test placement positions and is measured there in a spatial relation to at least one reference mark in each case. The described implementation of the method with different placement positions has the advantage that the placement accuracy of the placement machine can be determined within a larger placement area.

According to a further exemplary embodiment of the invention, the test placement position and the further test placement position have a first distance from one another along a first direction, which is smaller than a first geometric dimension of the test component along this first direction. The geometric dimension of the test component along this first direction relates to an orientation of the test component when it is currently on the reference plate.

In clear terms, the relatively small spacing of the two test placement positions in relation to the size or dimension of the test component means that the optical recordings of one test component are carried out on overlapping test placement areas. A test placement area is to be understood as that surface area on the reference plate which is occupied by the test component at the respective test placement position.

The described determination of the placement accuracy with overlapping test placement positions or, more precisely, with overlapping test placement areas can be particularly advantageous if the test components are large-area components and / or if the placement precision of the placement machine has a high spatial resolution is to be determined in the placement area of the placement machine occupied by the reference plate.

The reference plate typically has a rectangular (or square) format. Said first direction then preferably runs parallel to a side edge of the reference plate.

According to a further exemplary embodiment of the invention, the test placement position and at least one other further test placement position have a second distance from one another along a second direction, which is smaller than a second geometric dimension of the test component along this second direction, the second direction is angled, in particular perpendicular, to the first direction. Furthermore, for the at least one other additional test placement position, another additional actual position is now also determined, taking into account (the position) of at least one other additional reference marking by means of the camera and the evaluation unit. The determination of the placement accuracy of the placement machine is also based on another further deviation between (i) the other further actual position determined and (ii) another further target position for the other further test placement position.

The geometric dimension of the test component along this second direction also relates to an orientation of the test component when it is currently located on the reference plate.

In clear terms, in this exemplary embodiment the test mounting areas also have an overlap along the second direction. As a result, in the case of a large-area test component, the placement accuracy can also be determined with a high resolution along the second direction.

According to a further exemplary embodiment of the invention, the further test fitting position is the same as the test fitting position. This means that the test component is placed several times at the same target position, with the actual test positions deviating more or less strongly from the one target position due to a naturally always finite placement accuracy. This deviation is naturally different for different assembly processes or different placements of the test component. In the case of multiple placement and subsequent measurement using one and the same nominal position, a repeat accuracy of the placement machine can be measured in relation to the respective (further) test placement position.

It should be noted that the method described can also be carried out in such a way that the test component is placed at different test placement positions and measured there, at least one test placement position or, more precisely, its target position being used more than once. This means that the sequence of steps (i) picking up, (ii) placing and (iii) determining (or measuring) is carried out with the test component at least three times, with at least two sequences with different target positions and at least two Sequences can be carried out with the same target position.

According to a further exemplary embodiment of the invention, the plurality of reference markings are distributed flat over the reference plate, in particular in the form of a one-dimensional or two-dimensional grid. This means that for each possible test placement position there is always at least one reference marking in the vicinity which can be used for the described relative distance measurement. As a result, a high level of accuracy can be guaranteed when determining the respective actual position of the placed test component.

The reference markings can be arranged spatially uniformly or statistically distributed on the reference plate.

According to a further exemplary embodiment of the invention, the determination of the actual position and / or the renewed determination of the further actual position includes a common optical detection of the test component and the relevant at least one reference mark by means of an image recording by the camera. This means that the test component and the relevant at least one reference marking can be detected at the same time. A camera movement between the detection of the test component and the reference marking is not necessary. As a result, a particularly high accuracy of the determination of the (relative) actual position of the placed test component or the renewed determination of the (relative) further actual position of the placed test component can be guaranteed.

According to a further exemplary embodiment of the method, the test component is picked up by a component feed device of the placement machine. This can mean in particular that the determination of the placement accuracy is carried out under very realistic conditions. This is because not only is component transport over a possibly very short transport route to the test placement position, but the entire component transport over a typically significantly longer one Transport route taken into account. This can be important because the behavior of a mechanical positioning or gantry system that carries the placement head can depend on the specific travel paths covered.

After it has been placed at the “last” test placement position and optically captured by the camera, the test component is preferably transported back by the placement head to the location of the component feed device from which it was picked up. Alternatively, it can also be brought to any other point on the component feed device, provided that it is “in good hands” there until the next determination of the placement accuracy of the placement machine.

The described “return” of the test component can be useful in particular in the case of a component feed device if it is a so-called “tray feeder”. With such a “tray feeder”, the (real) components to be assembled are presented to the assembly head for collection on a flat shelf. Each component is in its own pick-up position.

According to a further exemplary embodiment of the invention, the method further comprises, after the placed test component has been picked up again by the placement head and before the newly picked up test component is placed again, (a) transporting the test component from the test placement position the component supply device and (b) transporting the test component from the component supply device to the further test mounting position. As a result, the placement accuracy can be determined not only with regard to a one-off pickup of the test component but also advantageously with regard to each assembly or placement process of the test component under realistic conditions. As a result, inaccuracies in the positioning or portal system that are dependent on the transport path can in principle be taken into account for all possible (further) test placement positions, which can then flow into a particularly realistic determination of the placement accuracy.

According to a further exemplary embodiment of the invention, the test component is a real component. This has the (cost) advantage that even a single (expensive) precision component can be dispensed with. A real component can be used in an advantageous manner in particular if it can be easily recognized optically based on characteristic structures and / or if it has a structural shape that is at least approximately constant within a type of component. In the case of a real component that can be used for the method described in this document (instead of a precision component described below), the characteristic structures should be located on an upper side of the component, whereas the component connection contacts are located on a lower side of the component.

According to a further exemplary embodiment of the invention, the test component is a glass module or a ceramic module. This has the advantage that the placement accuracy can be determined particularly precisely. This applies in particular when modules are used which have suitable, high-precision markings for better optical recognition or measurement.

Due to the reuse of the test component according to the invention, it is advantageously not necessary for the operator of a placement line with one or more placement machines to keep a plurality of such test components, which are typically very expensive. In this way, investment costs can be saved without having to forego a highly precise determination of the placement accuracy. The cost advantage described is particularly important when the placement accuracy is to be carried out with a large test component in order to simulate the accuracy of the placement with large and typically very heavy components as precisely as possible. This is because large test components are particularly expensive.

According to a further exemplary embodiment of the invention, the test component is designed as a two-piece test component and has (a) a flat precision element, which is designed as a glass plate or ceramic plate, and (b) a weight element with a flat top on which the precision element is attached.

The purpose of the weight element is to determine the placement accuracy even under real placement conditions when the components to be actually placed are large or heavy components. The two-piece design of the test component described has the advantage, compared to a one-piece design exclusively with expensive glass or ceramic material, that the test component can be produced comparatively inexpensively. This is because a significantly more cost-effective material, for example aluminum, can be selected for the formation of the weight element.

The precision element can be designed as a small glass plate or ceramic plate. The precision element preferably has optically recognizable precision markings on its upper side.

The precision element and the weight element can be attached to one another with an adhesive. For example, a permanent adhesive such as a superglue can be used as the adhesive.

In this context, the expression “flat” can be understood in particular to mean that the thickness of the precision element is significantly smaller than at least one length or width dimension of the precision element. The thickness is preferably smaller by at least a factor of 10 than the length or the width of the precision element.

According to a further exemplary embodiment of the invention, the placement head is a multiple placement head which has a first plurality of component holding devices. Furthermore, the method is carried out with a second plurality of test components, the second plurality being smaller than or equal to the first plurality. This exemplary embodiment, in which a multiple placement head is used, is characterized in that (a) the second plurality of test components is picked up by the multiple placement head; (b) the second plurality of test components is placed on the reference plate using the multiple placement head in such a way that each test component is assigned a test placement position; (c) for each test component placed at a test placement position, an actual position is determined by means of the camera and the evaluation unit, taking into account (the position) in each case at least one reference marking; (d) the second plurality of placed test components is picked up again by the multiple placement head; (e) the second plurality of test components is placed again on the reference plate using the multiple placement head in such a way that each test component is assigned a further test placement position, the further test placement positions being different from the test Placement positions; (f) for each test component placed at a further test placement position, a further actual position is determined again by means of the camera and the evaluation unit, taking into account (the position) of at least one reference mark in each case; and (g) the placement accuracy of the placement machine is determined based on deviations between a determined actual position and an assigned nominal position for the respective test placement position and further deviations between a further determined actual position and an assigned further nominal position for the respective further test placement position.

In clear terms, in this exemplary embodiment, the (second) plurality of test components is first fitted and captured by the camera. A test component can be detected immediately after it has been placed and before the other test components have been placed. Alternatively, further test components of the remaining test components can also be placed before the optical detection and only then can several and preferably all test components be optically detected by the camera.

The described process sequence with a multiple placement head has the disadvantage that not only one test component is required, but that several possibly expensive test components are required. On the other hand, the method can be carried out particularly quickly, because several (test) components are picked up, transported together and then carried out within a comparatively short period of time due to the known capability of a multiple placement head according to the so-called “collect and place” principle can be equipped or placed within a very short period of time.

The number of test mounting positions is typically greater than the second plurality. The number of test fitting positions is preferably an integral multiple of the second plurality. However, it is also possible that not all test components picked up by the multiple placement head are placed (and measured) in at least one cycle.

According to a further exemplary embodiment of the method, the second plurality of test components is the same size as the first plurality of component holding devices. As a result, the above-described ability of the multiple placement head can be optimally used. This has the advantage that the method described can be carried out particularly effectively in terms of time. A longer interruption of a placement operation of the placement machine is also not necessary to achieve a high accuracy of the determination of the placement accuracy.

According to a further aspect of the invention, an assembly machine is described for assembling a circuit carrier with electronic components. The placement machine described has (a) a chassis; (b) a receiving device attached to the chassis for receiving a circuit carrier to be assembled; (c) a gantry system having a stationary component stationarily attached to the chassis and a movable component positioned relative to the stationary component can; (d) a placement head which is attached to the movable component and which is configured to pick up components and, after suitable positioning of the movable component, to fit the circuit carrier with the components, each component being mounted on the circuit carrier at a predetermined placement position; (e) a camera for optically detecting the position of the circuit carrier introduced into a placement area of the placement machine and for optically detecting the position of assembled components; and (f) a data processing device which communicates with the portal system ( 110 ), the placement head ( 130 ) and the camera is coupled and which is configured to control or carry out the method described above for determining the placement accuracy of the placement machine. The placement machine is set up to determine the accuracy of the placement machine to sequentially place test components instead of components on a reference plate which has been introduced into a placement area of the placement machine instead of the circuit carrier.

In order to be able to carry out the above-described method for determining the accuracy of the placement machine, it is necessary that the holding device can also hold the reference plate instead of a circuit carrier to be fitted. Furthermore, the placement head must also be able to pick up a test component (instead of a real component) and place it at a predetermined placement position on the reference plate. In addition, the camera, which can preferably be moved together with the placement head by suitable actuation of the portal system, must also be able, instead of a marking on a circuit carrier that is actually to be fitted, to also at least the placed test components as well as those in the vicinity to capture a reference mark. However, the provision of these three required functionalities does not require any equipment modifications to the structural configuration of a conventional placement machine. The method according to the invention can therefore be implemented in a simple manner by suitable programming of the data processing device. In addition, the function of the evaluation unit described above can also be provided by the data processing device by suitable programming of the data processing device.

It should be noted that embodiments of the invention have been described with reference to different subjects of the invention. In particular, some embodiments of the invention are described with method claims and another embodiment of the invention with a device claim. However, when reading this application, it will immediately become clear to the person skilled in the art that, unless explicitly stated otherwise, in addition to a combination of features belonging to one type of subject matter of the invention, any combination of features relating to different types of Subjects of the invention belong.

Further advantages and features of the present invention emerge from the following exemplary description of currently preferred embodiments.

Figure list

• 1 shows a placement machine according to an embodiment of the invention.
• 2a until 2c each show a sequential placement of one and the same test component on a reference plate, which was introduced into the placement area of the placement machine instead of a real circuit carrier.
• 3 shows a two-piece test component which has a precision element and a weight element.
• 4th shows the position of a placed test component on a reference plate on the basis of (i) markings on the test component and (ii) reference markings on the reference plate.

Detailed description

It is pointed out that in the following detailed description, features or components of different embodiments that are identical or at least functionally identical to the corresponding features or components of another embodiment are provided with the same reference symbols or with reference symbols which are shown in FIG the last two digits are identical to the reference symbols of corresponding identical or at least functionally identical features or components. To avoid unnecessary repetition, features or components that have already been explained using a previously described embodiment are no longer explained in detail at a later point.

1 shows a schematic representation of a placement machine 100 according to an embodiment of the invention. The placement machine 100 is used in the application described here to create components 190 from a shelf 125 a component feed device designed as a so-called “tray feeder” 120 to be taken and on a component carrier or circuit carrier 180 to put on or to assemble.

How out 1 can be seen, the placement machine 100 a chassis 102 on what a frame or. Support structure for various components of the placement machine 100 represents. The component feeding device 120 is (detachable) on the chassis 102 attached. Circuit carriers to be assembled 180 are made by means of a receiving device designed as a transport device 104 in a placement area of the placement machine 100 transported and provided there for the assembly process. The circuit carrier in question is at a placement position 180 fixed in a manner not shown. By means of the receiving device designed as a transport device 104 are the circuit carriers to be assembled 180 however, not only fed to the assembly process, but after at least partial assembly of the circuit carriers 180 also transported away, so that subsequently a next circuit carrier 180 can be equipped.

The actual placement process is carried out by a placement head 130 carried out. The placement head 130 is the circuit carrier in one to the transport direction (arrow x) 180 parallel direction (double arrow x) on a movable support arm 114 appropriate. The movable carrier arm 114 is on a stationary support arm 112 attached, which is firmly attached to the chassis 102 is connected and the receiving device designed as a transport device 104 overstretched. The movable carrier arm 114 can be moved transversely (double arrow y) to the transport direction. The stationary support arm 112 represents a stationary component of a portal system 110 the placement machine 100 represents, the movable carrier arm 114 represents a moving component of the portal system 110 The portal system 110 thus enables a two-dimensional movement or positioning of the placement head 130 in an xy plane, which is spanned by the x direction and the y direction.

Before the assembly process of at least one component 190 becomes the placement head 130 using the portal system 110 to the component feeder 120 driven where he has a component 190 records. Then it is over the circuit carrier to be assembled 180 proceed where he has the component 190 on the circuit carrier 180 settles. In the case of a so-called multiple placement head, several components are placed directly behind one another 190 each picked up with a component holding device which is designed, for example, as a suction gripper and is not shown. Then the multiple placement head is moved into the placement area and the components are picked up there 190 directly behind one another on the circuit carrier 180 placed.

The placement machine 100 furthermore has two cameras, a first stationary camera 140 and a second movable camera 150 .

The first stationary camera 140 is according to the embodiment shown here between the component feeding device 120 and the assembly area in which the circuit carrier to be assembled is located 180 is located. The stationary camera 140 is directly or indirectly related to the chassis 102 connected and has a field of view which is directed upwards, ie in 1 out of the plane of the drawing. Unless the placement head 130 above the first camera 140 is located, this can be a component 190 , which from the placement head 130 is held by means of a suction gripper, not shown, grasp from below. The first camera 140 is therefore also referred to as a component camera.

The second moving camera 150 is according to the embodiment shown here on the movable support arm 114 attached and can be just like the placement head 130 be moved along the x-direction illustrated by a double arrow. The second camera 150 , which are also directly on the placement head 130 can be attached, has a downward field of view, ie from above into the plane of the drawing 1 into it. The second camera 150 can thus on the circuit carrier 180 Detect attached or formed markings (not shown). This can change the position of the circuit board 180 can be determined in the placement area. The second camera 150 is often referred to as a circuit board camera.

The placement machine 100 also has a data processing device 160 on, which, shown schematically by dashed lines, in particular with the two cameras 140 and 150 as well as with the placement head 130 is communicatively coupled. The data processing device 160 ensures, through a suitable control of drive motors or actuators for the operation of the placement head 130 and for positioning the placement head 130 using the portal system 110 . Furthermore, according to the exemplary embodiment shown here, image processing is carried out by the two cameras 140 and 150 recorded images also by the data processing device 160 performed.

2a , 2 B and 2c each show a sequential placement of one and the same test component 290 on a reference plate 280 , which instead of a real circuit carrier 180 in the placement area of the in 1 illustrated placement machine 100 was introduced.

In the embodiment according to 2a becomes the test component 290 placed one after the other at four different test placement positions. The test component is placed at each of these test placement positions 290 together with at least one adjacent reference mark 282 from the movable second camera 150 the in 1 illustrated placement machine recorded. By evaluating an image from one of the cameras 150 downstream evaluation unit is the exact actual position of the placed test component for each test placement position 290 determined. The placement accuracy of the placement machine 100 is determined according to the embodiment shown here based on four deviations, each deviation being assigned to a test placement position. Specifically, there is a spatial deviation between the respectively determined actual position and a target position for each test placement position.

In the embodiment according to 2 B becomes the test component 290 placed sequentially at four test placement positions in such a way that it each occupies a test placement area, with at least two adjacent test placement areas having a certain spatial overlap. The four test placement positions lie on a straight line which runs along a first direction, which in 2 B with the arrow 290a is marked.

In the exemplary embodiment shown here, the first three test placement positions are so close to one another that there is even an overlap between the first test placement area and the third test placement area. In a corresponding manner, there is also an overlap between the second test placement area and the fourth test placement area. Due to the short distances between the different test placement positions, the placement accuracy can be along the first direction 290a can be determined with a significantly higher spatial resolution than would be the case with non-overlapping test placement areas.

In the embodiment according to 2c becomes the test component 290 placed sequentially at eight test placement positions. As can be seen from this figure, the corresponding test mounting surfaces do not only point along the first direction 290a but also along a second direction perpendicular thereto 290b an overlap. It should be noted that both along the first direction 290a as well as in particular along the second direction 290b more than the illustrated test placement positions are possible, despite the "large area" of the test component 280 over the whole reference plate 280 or the entire placement area of the placement machine 100 a high spatial resolution when determining the placement accuracy of the placement machine 100 to reach.

3 shows a two-piece test component 390 with which the placement accuracy of the placement machine 100 can be determined for large-area and comparatively heavy components under real conditions. The two-piece test component 390 has a highly precisely manufactured precision element 392 on. According to the embodiment shown here, the precision element 392 a comparatively small glass plate on which a plurality of highly precisely positioned, optically recognizable markings are formed, including four markings 393 in each corner of the glass plate.

In order to minimize optical parallax errors and thus an unwanted offset during optical detection through the glass plate, the glass plate should 392 be as thin as possible. In order to nevertheless create a test component which has a comparatively high weight and consequently can well simulate a real placement process of comparatively heavy components, the test component 390 a weight element 396 on. According to the embodiment shown here, the weight element is a metal carrier 396 made of aluminium. The weight element 396 and the precision element 392 are connected to one another in a non-slip manner by means of a thin, double-sided adhesive film.

How out 3 can be seen in the weight element 396 in four corner areas, which when the precision element is glued on 392 with the markings 393 overlap, recesses or openings 396a educated. Their function is described below in relation to 4th explained in more detail.

4th shows the position of the placed test component 390 on a reference plate 280 . In the representation of 4th the test component is located 390 with the glass plate 392 above or on the reference plate 280 . As already mentioned above based on the 2a until 2c described, the reference plate has a plurality of flatly distributed reference markings on its upper side 282 on. From these reference marks 282 are in 4th those not to be seen, which of the opaque weight element 396 of the placed test component 390 are covered. This means that only those reference marks 282 can be detected by a camera, which is located laterally next to the assembled test component 390 or which through the transparent glass plate 392 and through the openings 396a are visible through. In addition, the camera can of course also use the four markings 393 capture which ones on the glass plate 392 are trained. This means that the camera can capture both the markings with a single image 393 of the test component 390 or more precisely the glass plate 392 as well as some reference marks 282 the underlying reference plate 280 can capture. By suitable relative measurements of the spacing between the markings 393 and the reference marks 282 can be the actual position of the on the reference plate 280 equipped test component 390 can be recorded with a very high degree of accuracy.

List of reference symbols

100

Pick and place machine

102

chassis

104

Receiving facility

110

Portal system

112

stationary component / stationary support arm

114

movable component / movable support arm

120

Component feeder / tray feeder

125

Storage space

130

Placement head

140

first camera / stationary camera / component camera

150

second camera / moving camera / circuit board camera

160

Evaluation unit

180

Circuit carrier

190

Component

280

Reference plate

282

Reference marks

290

Test component

290a

first direction

290b

second direction

390

Test component

392

Precision element / glass plate

393

Structure / marking of precision element

396

Weight element / metal carrier

396a

opening

Claims (15)

A method for determining the placement accuracy of a placement machine (100), the method comprising Introducing a reference plate (280) into a placement area of the placement machine (100), the reference plate (280) having a plurality of reference markings (282); Picking up a test component (290, 390) from a placement head (130); Placing the gripped test component (290, 390) at a test placement position on the reference plate (280) using the placement head (130); Determining an actual position of the placed test component (290, 390) taking into account the position of at least one reference marking (282) by means of a camera (150) and an evaluation unit (160) connected downstream of the camera (150); renewed picking up of the placed test component (280) by the placement head (130); Repositioning the newly picked up test component (290, 390), now at a further test placement position, on the reference plate (280) using the placement head (130); again determining, now a further actual position of the newly placed test component (290, 390), taking into account the position of at least one further reference marking (282) by means of the camera (150) and the evaluation unit (160); and Determining the placement accuracy of the placement machine (100) based on a deviation between (i) the determined actual position and (ii) a target position for the test placement position and a further deviation between (i) the further actual position determined again and (ii) a further target position for the further test placement position. Procedure according to Claim 1 , the further test mounting position being different from the test mounting position. Procedure according to Claim 2 , wherein the test placement position and the further test placement position along a first direction (290a) have a first distance from one another which is smaller than a first geometric dimension of the test component (290, 390) along this first direction (290a). The method according to the preceding claim, wherein the test placement position and at least one other further test placement position along a second direction (290b) have a second distance from one another which is smaller than a second geometric dimension of the test component (290, 390) along this second direction (290b), the second direction (290b) being angled, in particular perpendicular, to the first direction (290a); and where for the at least one other further test placement position likewise, now another further actual position, taking into account the position of at least one other further reference marking (282) is determined by means of the camera (150) and the evaluation unit (160), the determination the placement accuracy of the placement machine (100) is also based on another further deviation between (i) the other further actual position determined and (ii) another further target position for the other further test placement position. Procedure according to Claim 1 , the further test mounting position being the same as the test mounting position. Method according to one of the preceding claims, wherein the plurality of reference markings (282) are distributed flat over the reference plate (280), in particular in the form of a one-dimensional or two-dimensional grid. The method according to the preceding claim, wherein the determination of the actual position and / or the renewed determination of the further actual position comprises joint optical detection of the test component (290, 390) and the relevant at least one reference marking (282) by means of an image recording by the camera (150). Method according to one of the preceding claims, wherein the test component (290, 390) is picked up by a component feed device (120) of the placement machine (100). Method according to the preceding claim, further comprising after the placed test component (290, 390) is picked up again by the placement head (130) and before the picked up test component (290, 390) is again placed, Transporting the test component (290, 390) from the test mounting position to the component feeder (120) and Transporting the test component (290, 390) from the component supply device (120) to the further test placement position. Method according to one of the preceding Claims 1 until 9 , wherein the test component (290, 390) is a real component. Method according to one of the preceding Claims 1 until 9 , wherein the test component (290) is designed as a glass block or ceramic block. Method according to one of the Claims 1 until 9 , wherein the test component (290) is designed as a two-piece test component (390) and has the following: a flat precision element (392), which is designed as a glass plate or ceramic plate, and a weight element (396) with a flat top on which the precision element (392) is attached. A method according to any one of the preceding claims, wherein the placement head (130) is a multiple placement head having a first plurality of component holding devices; and wherein the method is performed with a second plurality of test components (290), the second plurality being less than or equal to the first plurality; whereby the second plurality of test components (290) are picked up by the multiple placement head (130); the second plurality of test components (290) is placed on the reference plate (280) using the multiple placement head (130) in such a way that each test component (290) is assigned a test placement position; for each test component (290) placed at a test placement position, an actual position is determined by means of the camera (150) and the evaluation unit (160) taking into account the position of at least one reference marking (282) in each case; the second plurality of placed test components (290) is picked up again by the multiple placement head (130); the second plurality of test components (290) is placed again on the reference plate (280) using the multiple placement head (130) in such a way that each test component (290) is assigned a further test placement position, the further test -Equipment positions are each different to the test assembly positions; for each test component (290) placed at a further test placement position, a further actual position is determined again by means of the camera (150) and the evaluation unit (160), taking into account the position of at least one reference marking (282) in each case; and the placement accuracy of the placement machine (100) is determined based on deviations between a determined actual position and an assigned target position for the respective test placement position and further deviations between each determined further actual position and an assigned further target position for the respective further test placement position. The method according to the preceding claim, wherein the second plurality of test components (290) is the same size as the first plurality of component holding devices. Assembly machine (100) for assembling a circuit carrier (180) with electronic components (190), the assembly machine (100) having a chassis (102); a receiving device (104) attached to the chassis (102) for receiving a circuit carrier (180) to be assembled; a portal system (110) having a stationary component (112) stationarily attached to the chassis (102) and having a movable component (114) which can be positioned relative to the stationary component (112); an assembly head (130) which is attached to the movable component (114) and which is configured to pick up components (190) and, after suitable positioning of the movable component (114), to assemble the circuit carrier (180) with the components (190) wherein each component (190) is mounted on the circuit carrier (180) at a predetermined placement position; a camera for optically detecting the position of the circuit carrier (180) introduced into a placement area of the placement machine (100) and for optically detecting the position of assembled components (190); and a data processing device (160) which is communicatively coupled to the portal system (110), the placement head (130) and the camera and which is configured to control the method according to one of the preceding claims; wherein the placement machine (100) is set up to determine the accuracy of the placement machine (100) test components instead of components (190) on a reference plate (280), which instead of the circuit carrier (180) in a placement area of the placement machine (100) has been introduced to place sequentially.

Images