Method for monitoring the application of a viscous mass by a dispenser in a production process, computer program, and computer system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SIEMENS AG
- Filing Date
- 2025-11-20
- Publication Date
- 2026-08-06
Smart Images
Figure EP2025083671_06082026_PF_FP_ABST
Abstract
Description
[0001] 202501103
[0002] 1
[0003] Description
[0004] Method for monitoring a dispenser application of a viscous mass in a manufacturing process, computer program and computer system
[0005] The invention relates to a method for monitoring a dispenser application of a viscous mass in a manufacturing process with the features of claim 1 and a computer program comprising a digital twin for controlling a method according to claim 14 and in a computer system with a computer program according to claim 15.
[0006] In manufacturing processes involving material application by dispensing a viscous mass (e.g., adhesives, solder pastes, conductive adhesives, underfill materials, varnishes, and others), a highly automated process must ensure that the viscous mass is safely applied to the intended location.
[0007] Current methods for verifying dispenser application include random checks using special product dummies, which are carrier plates with holes on the top and indicator paper applied there. Alternatively, detectors that detect the interruption of a light beam, for example using laser light barriers, can also verify the application. Detecting the viscous mass on the products being manufactured is difficult using visual methods, especially when the mass is transparent. Therefore, continuous, automated, and production-integrated monitoring of transfer quality at the product level is currently unsatisfactory.
[0008] The object of the invention is to provide a method for carrying out a dispenser application 2 of a viscous mass in a manufacturing process and monitoring it, by which defects in the application of the viscous mass can be detected before the actual irreversible manufacturing process.
[0009] The solution to the problem consists of a method for monitoring a dispenser order with the features of claim 1, as well as a computer program comprising a digital twin for controlling a method according to claim 14, and a computer system with a computer program according to claim 15. 202501103
[0010] 2
[0011] The inventive method for carrying out a dispenser application 2 of a viscous mass in a manufacturing process 4 with a method for monitoring the dispenser application comprises the following steps:
[0012] - Defining wetting areas in relation to an image of an application surface - Generating a thermographic image of the application surface selectively coated with viscous material,
[0013] - Defining adjustment points on the application surface that are identifiable on the illustration and on the thermographic image,
[0014] - Overlaying the image and the thermographic image using the adjustment points - Comparing the position of emissivity anomalies on the application surface, identified by the thermographic image, with the position of the wetting area on the image.
[0015] The described method has the advantage that the application surface, i.e., the surface onto which an adhesive layer is applied, is thermographically examined before the adhesive bonding process, thus allowing application defects to be corrected before final completion. It has been observed that after a certain period following application, temperature anomalies occur at the wetted surfaces compared to the surrounding area. These temperature anomalies, which will be defined in more detail below, result, among other things, from the enthalpy of vaporization that occurs during the partial evaporation of components of the viscous mass, particularly solvents, and draws heat from the wetted surface. For this reason, the wetted surfaces of the application are cooler than the unwetted surfaces.If the thermographic image is compared with an image taken before wetting (a photographic image or a digital twin of the image from a CAD system), it can be determined, using fixed points referred to here as adjustment points, whether the specified wetting areas are actually covered with the viscous mass and whether it is sufficiently applied, if the temperatures there are lower than on the other surfaces of the application surface.
[0016] In this way, targeted influence can be exerted on the manufacturing process, thus improving the quality assurance of the process compared to the state of the art.
[0017] The following definitions are given for the terms used in the patent claims: 202501103
[0018] 3
[0019] Manufacturing process: A manufacturing process generally encompasses all processes in which a viscous material is applied to a wetting surface, typically a substrate or component surface, using a dispenser. Such manufacturing processes include, in particular, those involving adhesives, solder pastes, conductive adhesives, underfill materials, sintering pastes, as well as silicones, lacquers, and / or resins, which are applied to the wetting surface using a dispenser. Here, the term dispenser is defined as a dispensing device for viscous materials with a viscosity greater than 50 mPa s, and especially greater than 500 mPa s. The dispensing of the viscous material is achieved using hydraulic pressure, air pressure, piston pressure, a spindle, and / or a jet valve, thereby applying a predefined quantity of the viscous material to the wetting surface.The dispenser therefore differs from other application methods such as a spray nozzle analogous to an inkjet printer or the spraying of a flux, since a dispenser, according to this definition, applies a viscous mass to the application surface, which in turn differs in its thermographic appearance from a low-viscosity liquid with a higher proportion of easily evaporating solvents.
[0020] The image of the application surface can be a design drawing, for example from a CAD program, or it can be a photographic image of the actual existing sample application surface. The image is stored in a computer system, for example in a plant control system such as a Siemens S71500 and / or its peripheral devices, or it is stored there after the image has been captured. Typically, the image is transferred to the computer system or plant control system in the form of pixels. The same applies to thermographic imaging, which is preferably carried out using infrared technology.
[0021] A thermographic image is a measurement of thermal radiation, which in the manufacturing environment under consideration typically manifests as infrared emission, and it allows conclusions to be drawn about different temperatures within the same environment. However, the varying emissivity of different materials must be determined through calibration. In the typical temperature environment, emission means emission in the form of IR radiation.
[0022] Different materials on the same surface with different IR emissions can exhibit different emissivities at the same temperature. This can be used to identify different materials on a surface. 202501103
[0023] 4
[0024] Alignment points are geometric shapes (not just points in the mathematical sense) on the application surface that are sufficiently distinctive to ensure an unambiguous correlation between the image and the thermographic image. For unambiguous alignment, at least two alignment points are preferably provided. The contact surfaces, for example, can already serve as alignment points. Based on the defined alignment points, the image of the application surface and the thermographic image can be superimposed. The term "superimposition" is used here in a figurative sense, analogous to an image and a transparent film.In the case of purely digital images, the superimposition consists of an electronic comparison, for example using an image analysis program, whereby the recording and the image are evaluated based on the defined adjustment points using individual pixels or pixel clusters.
[0025] Emissivity anomalies are generally temperature anomalies. These appear as points or areas visible in thermographic images that exhibit a temperature difference (or a material difference) compared to the surrounding surface. Typically, a temperature anomaly does not necessarily exhibit a constant temperature; rather, it contains a temperature range that does not intersect with the temperature range of the surrounding surfaces. Therefore, defining a threshold temperature—or more generally, an emissivity threshold—is useful for establishing a boundary between the temperature anomaly and the surrounding surface.
[0026] The term "time interval" refers to the period from the application of the flux to the flux-wetting surface until a defined point in time for a final thermographic image. However, since multiple thermographic images can be taken within this time interval (for example, using infrared video recording), it can also be useful to consider the temperature as a function of time and compare it to an empirically determined temperature-time profile (reference profile). In this case, the term "temperature" refers to a point on the temperature-time curve, such as the endpoint of the curve. For this purpose, it is advantageous to define a tolerance range for the reference profile. This could, for example, consist of one or two curves parallel to the reference profile, within whose range the considered temperature-time profile should lie.The temperature-time profile under consideration corresponds to the time interval. It is not absolutely necessary to evaluate multiple thermographic images within this time interval. 202501103.
[0027] 5
[0028] A digital twin is a digital representation of a tangible or intangible object or process from the real world in the digital world. Digital twins enable comprehensive data exchange. They are more than just data; they consist of models of the represented object or process and can also include simulations, algorithms, and services that describe or influence the properties or behavior of the represented object or process, or enable services based on it.
[0029] In a preferred embodiment of the invention, an emission threshold is defined for the temperature anomalies. This makes it easier to distinguish the emission anomalies from the surrounding surfaces of the application surface during evaluation.
[0030] In a further preferred embodiment of the invention, a measure to influence the manufacturing process is initiated if, within a time interval after the application of the viscous mass, an emissivity E, determined by thermographic imaging, is found at a wetting surface beyond the emission threshold. In this way, the quality of the component to be manufactured (for example, the adhesive bond) can be improved by directly intervening in the manufacturing process and in the upstream dispenser application.
[0031] One measure could be to reapply the viscous substance (for example, solder paste or adhesive paste) to the detected wetting area. Another advantageous measure could be to clean the dispenser, particularly its application opening.
[0032] The temperature within the temperature anomaly can be measured at a specific time after the application of the viscous mass. However, it is also useful to consider the temperature as a function of time. This allows for a more precise observation of the evaporation behavior of the applied viscous mass or its components, thus providing more reliable information about the actual quantity of mass applied to a specific location. This, in turn, enables even better quality assurance.
[0033] For this purpose, it is again useful to record a reference temperature-time curve at a defined wetting surface Z and compare it with the temperature under consideration.
[0034] 6
[0035] The temperature-time profile is compared. That is, an empirically determined reference profile of temperature development over time, where the applied quantity of viscous mass is precisely known, can be used to correlate the currently measured temperature-time profile with a specific quantity of mass. For this purpose, it is again advantageous to define a tolerance range for the reference profile. The measure to influence the manufacturing process is only initiated if the considered temperature-time profile lies outside this tolerance range.
[0036] The measure is only triggered if the temperature at the wetting surface exceeds the temperature threshold. If this occurs, too little viscous compound has been applied, since, as mentioned previously, the enthalpy of vaporization of components of the viscous compound leads to local cooling of the application surface. If this cooling does not occur due to insufficient application, the temperature remains higher than the temperature threshold.
[0037] In a further embodiment of the invention, the thermographic image is designed such that multiple images are captured within a given time period. This typically involves video recording, particularly using an infrared video camera. Alternatively, the image can be a photographic image of the application surface under observation. This photographic image can be taken of the actual application surface after the application of a viscous material and then transferred digitally into a computer program or system.
[0038] A further component of the invention is a computer program comprising a digital twin used to control a method for monitoring the application of a viscous mass in a manufacturing process according to any one of claims 1-13. In this computer program, the image is represented as a digital image, and the wetting surfaces and adjustment points are stored as components of the digital image. This computer program preferably serves to compare the image with the corresponding points marked on it with the thermographic images and to automatically generate an error message if, according to the aforementioned method claims, the dispenser application does not conform to the specified parameters shown in the image.
[0039] 7
[0040] Another component of the invention is a computer system with a computer program according to claim 14. The computer system can, for example, be a process control system. However, a cloud-based control solution can also be used.
[0041] Further examples and advantageous features of the invention are explained in more detail with reference to the following figures. These are purely exemplary embodiments and do not represent a limitation of the scope of protection. Features in a general designation and with a specific designation based thereon are identified by the same reference numeral.
[0042] This shows:
[0043] Figure 1 shows a schematic flow chart of the procedure and an exemplary process for applying a viscous mass using a dispenser.
[0044] Figure 2, a schematic representation of the application of a viscous mass to an application surface using a dispenser,
[0045] Figures 3a and c, thermographic images of the application surface,
[0046] Figure 3b, an illustration of the application surface and
[0047] Figure 3 shows a time-temperature curve of temperature anomalies on the application surface.
[0048] Figure 1 shows a schematic representation of a manufacturing process 4 in which a viscous mass 14, for example, adhesives, solder pastes, conductive adhesives, underfill materials, sintering pastes, but also silicones, lacquers and / or resins, is applied to an application surface by means of a dispenser 3. Furthermore, a logical sequence of a method integrated into the manufacturing process for monitoring a dispenser application within the manufacturing process is shown. First, a conveyor belt 32 is provided on which a component or semi-finished product 34 with an application surface 10 is transported. Figure 2 illustrates in more detail the actual application process (generally referred to as dispenser application 2 in Figure 1) of the viscous mass 14 by means of a dispenser 3.An application nose 5 of the dispenser 3 can be moved in its angle to the application surface 10 by means of a control unit, which can, for example, be an integral part of a computer system 30. Likewise, this described control unit 202501103.
[0049] 8
[0050] The dispenser application 2 is deliberately interrupted so that, at the intended time, viscous mass 14 hits the application surface 10 at the intended location.
[0051] The procedure for monitoring the dispenser application 2 is now carried out. For this purpose, a thermographic image 12 is taken using an infrared camera 36, and the thermographic image 12 is integrated into a computer system 30. A figure 8 of the application surface 10 is also stored in the computer system 30. This figure 8 can, for example, be an excerpt from a CAD system of the component 34 (the component 34 can also be a semi-finished product), but it may also be advantageous to simultaneously take a photometric image of the application surface 10 with the thermographic image 12. In this case, both the photometric image of figure 8 and the thermographic image 12 are entered into the computer system 30 during the process and digitally compared.
[0052] In this digital comparison, also referred to as the overlay of Figure 8 and the thermographic image 12, both Figure 8 and the thermographic image 12 are decomposed into individual pixels and compared with respect to predefined alignment points 16. The alignment points 16 are characteristic points that are electronically identifiable on both Figure 8 and the thermographic image 12. Suitable alignment points 16 can be the wetting surfaces 6. For example, in an adhesive bonding process, the wetting surfaces 6 can be the positions on the component 34 where an adhesive strip is applied; in a soldering process, they are the surfaces that are coated with solder paste.
[0053] It has been found that the application of the viscous mass 14 causes a local cooling of the application surface 10 due to the evaporation process of the volatile substances in the mass 14. This local cooling is due to the enthalpy of vaporization, which extracts heat from the wetting surface 10 precisely at the point of contact 6. This local cooling on the printed circuit board surface 10 can be observed as temperature anomalies in the thermographic image 12, which is usually in the form of an infrared image. The definition and evaluation of these temperature anomalies 18 will be discussed further below. An additional effect in this context is that different materials and differently treated surfaces exhibit different emissivities at the same temperature. These deviations can be seen in the thermographic image 202501103.
[0054] 9
[0055] They can either be calibrated out or they could be used directly for the detection of the applied viscous mass.
[0056] This described superimposition of image 12 and figure 8 takes place in the aforementioned computer system 30. This computer system 30 can contain a computer and a database. Furthermore, the computer system 30 can include a process control unit, such as a Siemens Simatic S 71500. This control unit, which is not explicitly shown here, controls the process and receives control information from other components of the computer system 30. It is also possible to perform the superimposition 40 directly in the control unit. Additionally, it may be advantageous to use cloud-based control for the manufacturing process 4 and for the described monitoring procedure. In this case, the computer system 30 would not be located, or would only be partially located, in close proximity to the manufacturing process 4.
[0057] Using the overlay 40, the computer system 30 calculates, based on determined reference data (which will be discussed in more detail later), whether the temperature anomalies 18 correspond to a satisfactory application of viscous mass 14 (temperature evaluation 42). If a positive temperature evaluation 44 is obtained, the manufacturing process 4 continues. In this case, the component 34 is fed into the production system 38 via the conveyor belt 32. The manufacturing process is carried out as planned, and the component 34 is then used for further processing. However, if the overlay 40 reveals that the determined temperature anomalies 18 do not meet the specifications (negative temperature evaluation 46), this may indicate a quality defect in the application of the viscous mass 14 to the defined wetting surfaces 6.
[0058] In this case, a data analysis 48 is carried out using the computer system 30.
[0059] Here, the available information from the thermographic image 12, Figure 8, as well as other, previously unmentioned process parameters, such as the functionality of the application nozzle 5 of the dispenser 3, are evaluated. The result may be, for example, that the application nozzle 5 is clogged or that the pressure for moving the viscous mass 14 in the dispenser 3 is too low. The movement control of the application nozzle 5 may also be faulty. Based on this information, a measure 22 is determined by means of data analysis 48, which counteracts possible quality defects in the dispenser application 2. This measure 22 may, for example, involve cleaning the application nozzle 5 or adapting the control of the 202501103.
[0060] 10
[0061] Application nose 5. Furthermore, measure 22 can also consist of removing the component 34 under consideration from the process and re-coating it with viscous mass 14.
[0062] Figure 3 shows an example of an application surface 10 designed as a printed circuit board surface 10. A viscous mass 14 in the form of a solder paste 14 is applied to this printed circuit board surface 10 using a dispenser 2. Figures 3a, 3b, and 3c each show the same section of the printed circuit board surface 10, with an infrared camera being used in Figure 3a. This is therefore a thermographic image 12, which is, however, very high-contrast. Temperature anomalies 18 occur, which, however, exhibit a certain gradual transition to their surroundings. At the defined wetting surfaces 6, which also serve as adjustment points 16, it is noticeable that the temperature is measurably lower than at the surrounding surfaces. Figure 3b shows Figure 8 of the same printed circuit board surface 10, which is an excerpt from the CAD model that was created for the design of the printed circuit board 34.In principle, a photographic image taken during the process would also be useful for this purpose. This would be particularly useful if further changes were to be expected as a result of the process, which would not be discernible using the purely calculated CAD figure 8. Figure 8 also contains the described wetting surfaces 6, which in turn represent the adjustment points 16.
[0063] Since, as shown in Figure 3a, the transitions of the thermographic image 12 are gradual, it is advantageous to define a temperature threshold 20 in order to represent a sharp boundary for the temperature anomaly 18. Figure 3c shows that the sharpened temperature anomalies 18 are particularly pronounced around the defined wetting area 6.
[0064] While the thermographic images 12 in Figure 3 allow for the visual representation of a sharply defined temperature anomaly 18 using the temperature threshold 20, for data analysis 48, electronic overlay 40 of Figure 8 and the thermographic image 12, and for further process control of the dispenser application 2 or the soldering process, it is advantageous to define more detailed criteria for the quality of the dispenser application 2. Several suitable and possible approaches exist for this purpose; one possible evaluation method will be described using Figure 4 as an example. Based on point Z, an exemplary wetting area in Figure 2b, the temperature recorded there is plotted in Figure 4 as a function of time.
[0065] described.202501103
[0066] 11
[0067] Figure 4 shows a time-temperature diagram at point Z from Figure 3. Here, point to and point h are defined on the time axis t. Point to is the time at which the viscous mass 14 is applied to the wetting surface 6, i.e., point Z, by means of the dispenser 3. Time h is the point of observation. The period between to and h is considered as a time interval 23. It is now possible to consider either a single point in time at h or the temperature profile at point Z during the temperature interval 23.
[0068] Considering the temperature profile during the time interval 23, it is advantageous to record a reference profile 24 in which a high-quality application of flux 14 was achieved by means of process evaluation. It is advantageous to define a tolerance range 28 around the reference profile 24, which results in upper and lower boundary lines for the reference profile 24. When considering only a singular point in time, this represents an upper and lower limit temperature at that point in time. The upper portion of the tolerance range 28 with respect to the temperature axis T preferably represents the temperature threshold 20 as a function of time t.
[0069] If we now consider the actual temperature-time profile in the time interval 23, this profile 26 should ideally lie within the tolerance range 28 around the reference profile 24. In this case, the quality criteria for applying the viscous mass 14 would be met, and the printed circuit board would (if these quality conditions are sufficient for all wetting surfaces 6) be transferred to a further process step (positive temperature evaluation 44 in Fig. 1). In the case of solder paste or sintering paste, this further process step would be heat treatment; in the case of adhesive paste, it would possibly be a curing step. However, if a considered temperature-time profile 26' lies outside the tolerance range 28, a measure 22 can be initiated in the manufacturing process 4, as described with respect to Figure 1 (negative temperature evaluation 46).As already explained, the application of a solder paste as a viscous mass 14 to a printed circuit board is only an example; alternatively, the same automated process can also be directed towards an adhesive bead or the dispenser application of a backing material or sintering paste.
[0070] When examining the temperature-time profile 26 according to Figure 4, a time-dependent thermographic image 12 is created using the infrared camera 36. A thermographic video is thus recorded along the time interval 23. A time-dependent image 202501103
[0071] 12
[0072] This has the advantage that a more detailed evaluation of the actual dispenser application 2 and the evaporation behavior can be carried out. The decision as to whether sufficient viscous mass 14 has been applied, which is made by data analysis 40, can thus be made more reliably, since it covers a longer period. In principle, however, a singular point in time, for example at time t1, can also be recorded and it can be examined whether the temperature measurement thus recorded is below the threshold value 20.
[0073] The advantage of the described method over the prior art is that the knowledge about local temperature anomalies 18 due to the evaporation of components of the viscous mass 14 is used to determine the amount of viscous mass 14 applied at defined locations, i.e., the wetting surfaces 6, and, if necessary, to implement quality assurance measures 22 for the manufacturing process 4. Through this knowledge and these implemented measures 22, the quality of the entire product, the component 34, can be improved and the reject rate reduced.
[0074] 13
[0075] Reference symbol list
[0076] 2 Dispenser Order
[0077] 3 Dispersers
[0078] 4. Manufacturing process
[0079] 5 application nose
[0080] 6 Wetting area
[0081] Figure 8
[0082] 10 Application interface
[0083] 12 Thermographic image
[0084] 14 viscous masses
[0085] 16 adjustment points
[0086] 18 emission anomalies
[0087] 20 emission threshold
[0088] 22 Measure
[0089] 23 Time interval
[0090] E Emission level
[0091] Temperature
[0092] 24 Reference history
[0093] 26 considered the Et course
[0094] Z defined wetting area
[0095] 28 Tolerance range
[0096] 30 computer systems
[0097] 32 conveyor belt
[0098] 34 Component
[0099] 36 Infrared camera
[0100] 38 Production plant
[0101] 40 Overlay Image / Recording 42 Evaluation
[0102] 44 positive temperature evaluation 46 negative temperature evaluation 48 data analysis
Claims
202501103 14 Patent claims 1. Method for carrying out a dispenser order (2) of a viscous mass (14) in a manufacturing process (4) with a method for monitoring the dispenser order (2) comprising the following steps: - Defining wetting areas (6) with respect to a representation (8) of an application surface (10) - Generating a thermographic image (12) of the application surface (10) selectively coated with viscous mass (14), - Defining adjustment points (16) on the application surface (10) that are identifiable on the illustration (8) and on the thermographic image (12), - Overlaying the image (8) and the thermographic image (12) using the adjustment points (16) - Comparing the position of emissivity anomalies (18) on the application surface (10), which are identified by means of the thermographic image (12), with the position of the wetting area (6) on the figure (8).
2. Method according to claim 1, characterized in that dispenser application (2) of the viscous mass is carried out by dispensing (3) adhesives, solder pastes, conductive adhesives, underfill materials and / or varnishes.
3. Method according to claim 2, characterized in that the viscous mass (14) applied by the dispenser (3) has a viscosity which is higher than 100 mPa s at 21 °C, in particular higher than 1000 mPa s 4. Method according to claim 3, characterized in that an emission threshold (20) is defined for the emission anomalies (18).
5. Method according to claim 4, characterized in that a measure (22) to influence the manufacturing process (4) is initiated if, within a time interval (23) after application of the viscous mass (14), an emissivity (E) determined by means of the thermographic image (12) at a wetting surface (6) is beyond the emission threshold (20).
6. The method of claim 5, characterized in that the emissivity (E) and / or the temperature (T) is considered as a function of time (t). 15 7. Method according to claim 6, characterized in that a reference profile (24) of an emissivity-time curve is recorded at a defined wetting surface (Z) and compared with the emissivity-time profile (26) under consideration.
8. Method according to claim 7, characterized in that a tolerance range (28) of the reference curve (24) is defined, and the measure (22) is initiated when the considered emissivity-time curve (26) lies outside the tolerance range (28).
9. Method according to claims 5 to 8, characterized in that the measure is carried out when the emissivity (E) at the wetting surface (6) is above the emission threshold (20).
10. Method according to one of the preceding claims, characterized in that the thermographic image (12) comprises a plurality of such images within a period of time.
11. Method according to one of claims 5 to 10, characterized in that as measure (22) a reapplication of the viscous mass (14) to the detected wetting surfaces is initiated.
12. Method according to one of claims 5 to 11, characterized in that, as measure (22), a cleaning of dispenser application nozzles is initiated.
13. Method according to one of the preceding claims, characterized in that the image (8) is a photographic image of the application surface (10) to be observed.
14. Computer program comprising a digital twin for controlling a method for monitoring a dispenser application (2) of a viscous mass (14) in a manufacturing process (4) according to one of claims 1 to 11, in which the image (8) is available as a digital image (8) and the wetting surfaces (6) and the adjustment points (16) are stored as part of the digital image (8).
15. Computer system with a computer program according to claim 14.