DE102017223501A1 - Method and device for detecting defects in electrical components or assemblies - Google Patents

Abstract

In a method for detecting defects in electrical components or assemblies, a scanning device with a plurality of magnetic field sensors is used, with which magnetic field components can be detected in three mutually perpendicular spatial directions. During a current flow through the electrical component or assembly to be measured, the magnetic field components in the three mutually perpendicular spatial directions are measured and recorded with the scanning device as a function of the location. The recorded magnetic field components are at least partially evaluated to detect defects in the electrical component or assembly. For the evaluation, a neural network is preferably used. The method and the associated device enable a non-contact detection of faults in electrical components or assemblies, in particular in the field of quality assurance.

Description

Technical application

The present invention relates to a method and a device for detecting and possibly localizing defects, in particular electrical defects, in electrical components or assemblies by measuring magnetic fields.

The timely detection of defects in electrical components or assemblies is an essential prerequisite for the reliable operation of the systems realized in all technical areas. The detection of defects and malfunctions is therefore important before use, for example in the production of the corresponding components or assemblies. This applies to all electrical components, for example in the fields of power electronics, electromobility or chip production. There is a need for suitable methods and apparatus for quality control of electrical components or assemblies during or after their manufacture.

State of the art

Defects within electrical components have heretofore been localized and identified in different ways. A defect is often only detected by improperly functioning assemblies. In some cases, thermographic methods are used because a changed or interrupted current flow leads to local heating or cooling compared to surrounding areas. However, many of the methods used so far are destructive, not sufficiently spatially resolved, not quantitative, e.g. the thermography or not sufficiently meaningful. Furthermore, only a few known methods can be integrated into a running process rail. Continuous quality control in the production of electrical components or assemblies is a major challenge.

The object of the present invention is to provide a method and a device for detecting defects in electrical components or assemblies, which can be integrated into a running process rail and also allows continuous quality control in the manufacture of electrical components or assemblies.

Presentation of the invention

The object is achieved with the method and the device according to claims 1 and 8. Advantageous embodiments of the method and the device are the subject of the dependent claims or can be found in the following description and the embodiments.

In the proposed method, a scanning device with a plurality of magnetic field sensors is used, with which magnetic field components can be detected in three mutually perpendicular spatial directions. During a current flow through the electrical component or assembly to be measured, the magnetic field sensors in the three mutually perpendicular spatial directions are measured with the scanning device at a constant distance of the magnetic field sensors to the surface of the electrical component or assembly to be measured at least over a two-dimensional portion of the surface as a function of location recorded. The recorded magnetic field components are then at least partially evaluated to detect defects in the electrical component or assembly. In this case, the current direction of the current flow can also be changed or even varied in order to gain additional information. The proposed method is preferably used for the detection of defects in all electrical components or assemblies in which electrical currents flow during operation, with the exception of solar cells and solar modules.

In the proposed method and the associated device is exploited that move in all electrically active components during operation of the components charge carriers. Moving charge carriers generate a magnetic field in their environment. Physics describes this phenomenon using the Maxwell equations. The magnitude and sign of the moving charges, as well as the magnitude and direction of their velocity, define the strength and direction of the magnetic forces and their underlying magnetic fields. In a rectilinear motion, a circular magnetic field is generated with respect to the direction of movement of the charge carriers. The magnitude of the magnetic field H is proportional to the quotient of the current I and the distance r to the conductor: $$\text{H}=\frac{I}{2\mathrm{\pi }r}$$

Each electrical component generates a specific for him three-dimensional magnetic field in space depending on the direction and number of moving charge carriers due to the moving charge carriers at each location. This corresponds to a very specific six-dimensional magnetic fingerprint of the component. For example, in power electronics, the magnitude of the magnetic field along the tracks at be highest. With a planar analysis of the magnetic field, in particular of the individual components Bz, Bx and By of the magnetic field, conclusions can be drawn about the direction and magnitude of the charge carriers. The term magnetic field is also used in the present patent application for the magnetic flux density. Defects and malfunctions in electrical components are always due to a changed current flow. This also changes the magnetic fingerprint of the component. Thus, with an at least two-dimensional analysis of the three magnetic field components Bx, By, Bz, it is possible to draw conclusions about specific defects. In the proposed method, the individual magnetic field components Bx, By and Bz are detected and evaluated by means of magnetic field sensors as a function of the location with the aid of a suitable scanning device. By means of a variation of the current (current and / or current direction) further information can be obtained.

Depending on the electrical component or assembly to be measured, the evaluation of the acquired measurement data is complex, but is preferably carried out fully automatically and self-learning. In a preferred embodiment of the method, this evaluation takes place via a neural network which automatically sorts the measurement data into classes. The higher the amount of data, the more significant the classification into the classes or the smaller the error of the classification. The measurement data are therefore fed in this preferred embodiment in a cloud-based evaluation, in which the measurement data are then classified and evaluated by the neural network. The classification preferably takes place in errors or error groups, one of the errors or error groups representing an error-free component or assembly.

Preferably, the scanning device used for area scanning comprises at least one line-shaped array of the magnetic field sensors, i. an arrangement of the magnetic field sensors along a straight or curved line. With such a scanning device with a linear array, the magnetic field components in the three mutually perpendicular spatial directions then by moving the linear array of magnetic field sensors at a constant distance to the surface of the measured electrical component or assembly - or the device in which this electrical component or assembly is measured and recorded as a function of location. As an alternative to the movement of the scanning device can of course also be moved to be measured electrical component or assembly relative to a stationary scanning device. In addition, the current, direction and voltage can be varied constantly or cyclically over all temperature ranges. Furthermore, it is also possible to use a planar arrangement of magnetic field sensors in the form of a planar array, which is to be understood as a distributed arrangement of the magnetic field sensors in a plane. The plane can also be curved. In this case, with sufficient expansion of the planar array, it is also possible to dispense with a relative movement between the electrical component or assembly and the scanning device if the array already covers the entire surface area of the component or assembly to be measured. It is also possible to arrange a plurality of line-shaped or planar arrays at different positions or in different orientations.

As magnetic field sensors, for example, Hall sensors or magnetoresistive sensors are used in the proposed device and the proposed method. In the preferred embodiment, the magnetic field sensors are 3D Hall sensors, so that with each of the magnetic field sensors, the magnetic field components in all three spatial directions can be detected.

In one embodiment, the magnetic field components recorded as a function of the location can be compared with reference data representing magnetic field components of a structurally faultless copy of the electrical component or assembly recorded as a function of the location. In this way, it is possible to conclude a faulty component by a simple comparison in the case of a deviation which occurs over a predefinable threshold value.

The proposed device for carrying out the method has a line-shaped or planar array of magnetic field sensors, with which magnetic field components can be detected in three mutually perpendicular spatial directions. The magnetic field sensors are arranged on one side of a carrier, in particular a carrier plate. On the opposite side of the carrier is a measuring unit, by means of which the magnetic field sensors can be used to measure and record the magnetic field components in the three mutually perpendicular spatial directions as a function of the location. In the support at least one metallic intermediate layer is integrated, by which a shielding of the magnetic field sensors against electromagnetic radiation of the measuring unit is achieved.

In an advantageous embodiment of the proposed device, the scanning device with the array of magnetic field sensors is designed such that a plurality of these scanning devices, preferably via a plug connection, can be mechanically and electrically connected to each other. The width or length of the linear or As a result, planar arrays of magnetic field sensors can be scaled as required.

In a further embodiment of the proposed device, when using a linear array of magnetic field sensors, it also has a device for position or displacement detection, which during the movement of the linear array determines a relative position of the array over a surface of an electrical component or assembly to be measured allows. In this embodiment, the line-shaped array preferably also has one or more spacers which allow the magnetic field sensors to be maintained at a constant distance from the surface of the electrical component or assembly to be measured during the movement of the linear array of magnetic field sensors. Furthermore, in such an embodiment, the device can also have a handle with which it can be moved manually at a constant distance from the surface of the component or assembly to be measured. In such an embodiment, the device is preferably approximated in shape to a window wiper or T-shape so that it can be pulled across the surface on the handle while simultaneously measuring and recording the magnetic field components as a function of location.

The surface of the component or assembly is scanned depending on the clock frequency with which the magnetic field sensors are read, and the movement speed of the scanning device relative to the surface (when using a linear array of magnetic field sensors) in a dense dot matrix. For each measuring point, the three magnetic field components (Bx, By, Bz) and two local components (x, y) corresponding to the location in the two-dimensional scanning area or scanning plane are obtained. During the measurement, a 5-dimensional result is thus obtained, which can be evaluated for the localization of any defects of the component or assembly. When using a flat array can be dispensed with a relative movement to the component or assembly, if the planar array is designed large enough to simultaneously detect all areas to be measured in a spatially resolved.

With the proposed method and the associated device a non-destructive and contactless detection of defects in electrical components or assemblies is possible. The method and the device are particularly suitable for the detection, characterization and localization of defects or defects also at the operating point of the different devices or electrical components or assemblies. In particular, the method and the device can also be easily integrated into a running process chain in order to enable a continuous quality control during the production of the electrical component or assembly or of a device equipped with these. It also enables observation of the development of individual faults, a time-dependent control of assemblies, an examination of the current state of an assembly as well as a prediction of faults with the help of a neural network. Compared to other known techniques, the scanning device used in the proposed method and apparatus represents a relatively inexpensive assembly.

The method and the device can be used in quality control and assurance in the manufacture of electrical components or assemblies or corresponding devices with such components or assemblies. It also allows for defect localization and classification in the advancement, research, and continuous control of assemblies and devices. The proposed method and associated apparatus can be applied to all assemblies and devices in which electrical currents flow, for example in power electronics, the automotive industry, in battery storage or in screen production.

list of figures

• 1 einen Querschnitt durch einen Abschnitt einer beispielhaften Ausgestaltung der vorgeschlagenen Vorrichtung;
• 2 eine Draufsicht auf die Sensorseite der Vorrichtung gemäß 1;
• 3 eine schematische Darstellung einer Steckverbindung zwischen zwei der linienförmigen Arrays bzw. Abtasteinrichtungen;
• 4 eine schematische Darstellung einer beispielhaften Ausgestaltung der vorgeschlagenen Vorrichtung für eine manuelle Messung;
• 5 eine schematische Darstellung einer beispielhaften Ausgestaltung der vorgeschlagenen Vorrichtung für eine Inline-Messung bei der Herstellung von Bauelementen;
• 6 eine schematische Darstellung einer weiteren beispielhaften Ausgestaltung der vorgeschlagenen Vorrichtung in Form einer Messbox; und
• 7 ein Beispiel für ein Messergebnis einer Messung der Magnetfeldkomponente By über einem zweidimensionalen Bereich der Oberfläche eines Bauteils.

The proposed method and the associated device will be explained in more detail below with reference to embodiments in conjunction with the drawings. Hereby show:

• 1 a cross-section through a portion of an exemplary embodiment of the proposed device;
• 2 a plan view of the sensor side of the device according to 1 ;
• 3 a schematic representation of a connector between two of the line-shaped arrays or scanning devices;
• 4 a schematic representation of an exemplary embodiment of the proposed device for a manual measurement;
• 5 a schematic representation of an exemplary embodiment of the proposed device for inline measurement in the manufacture of components;
• 6 a schematic representation of another exemplary embodiment of the proposed device in the form of a measuring box; and
• 7 an example of a measurement result of a measurement of the magnetic field component By over a two-dimensional area of the surface of a component.

Ways to carry out the invention

In the following, an exemplary implementation of the proposed device is described in which the scanning device has a line-shaped array of magnetic field sensors, with which the respective magnetic field components Bx . by and Bz can be detected in three spatial directions. The magnetic field sensors 1 are here on one side of a strip-shaped carrier 2 arranged along a line, hereinafter referred to as front, while the measuring unit with the components 3 for measuring, recording and transferring the measurement data on the opposite side of the carrier 2 are arranged, hereinafter referred to as the back. This is in 1 shown in cross section through an enlarged portion of the scanning device. The front side is as dense as possible with corresponding magnetic field sensors 1 , For example, commercially available geomagnetic sensors equipped. Front and back of the carrier 2 are through a metallic interlayer 4 (here: double layer) separated from each other, through which the magnetic field sensors 1 be shielded by electromagnetic fields of the measuring unit. The magnetic field sensors 1 should be as close as possible to the surface or the measuring range of the electrical components or assemblies to be measured.

The magnetic field sensors 1 are made in this example in a 3D packaging process to ensure mechanical stability and water resistance. The measurement data of the magnetic field sensors 1 are recorded in parallel and handed over unprocessed to a microcomputer. With the proposed device, a cross section through the space of a magnetic field of all three magnetic field components ( Bx . by . Bz ). Both the location and all spatial components of the magnetic field are detected at the same time, provided with a time or place stamp and transferred to the microcomputer. The 5 -dimensional result can then be evaluated as desired. In principle, a section of the complex magnetic field of each electrical component can be recorded in this way. Both the direction and the strength of the flowing streams can be qualitatively and quantitatively analyzed here.

2 shows still a plan view of the entire front of the device with the linear array of magnetic field sensors 1 , The carrier 2 In this example, it has a width of about 15 mm and a length of about 100 mm. In the present example, the scanning device is designed so that it can be extended with further scanning devices by a connector. 3 shows an example of such a connector with corresponding plug-in elements 5 , In this way, the proposed device can be scaled almost arbitrarily in size.

As already described, a functioning electrical component has a typical magnetic field distribution of the different spatial components of the magnetic field. Each defect now leads to a change in the current flow, which in turn leads to a change in the magnetic field. The 5D analysis of this magnetic field can be used both for quality control and for the localization and classification of defects. Also, a quantitative statement about the condition or the quality of the component can be made.

The 4 and 5 show two possible embodiments of the proposed device for manual measurement ( 4 ) as well as for an inline measurement ( 5 ). The two devices shown each have one or more magnetic field line sensors in order to be able to measure an entire area with one measurement. The funky way is in the design of the 4 with a mechanical or optical transducer, in the embodiment of 5 by the movement of the conveyor belt 7 detected. In the manual execution of the device 6 according to 4 The device is using the handle 8th moved manually over the components or assemblies to be measured. For this purpose, the device 6 corresponding wheels 9 at the same time ensure compliance with a constant distance of the scanning device or the linear array of magnetic field sensors relative to the surface. In case of inline measurement of 5 is the device 6 attached to a bridge-like arrangement over the conveyor belt 7 is arranged, on which move the components or assemblies to be measured. In both cases, the measurement data is stored in a computer and then transferred to a cloud for evaluation of the large amounts of data. The computer can in this case be provided separately from the device, wherein the data transmission can then take place, for example, wirelessly. The computer can also be designed as a small computer and installed in the device itself. Within the cloud is a self-learning neural network, which evaluates the measurement data and returns results or even recommended actions to the user. By means of a camera, for example, a label on the measured component or assembly can be identified and recorded, or even measured locations can be stored. It is also possible to equip the device with conventional electronics such as GPS sensors and Wifi connections for localization and / or external communication.

6 shows another example of a possible embodiment of the proposed device. Here the device becomes a measuring box 10 realized in at least two sides or wall surfaces in each case a planar array 11 is integrated by magnetic field sensors, as the example of 6 is recognizable. It can be a box of a size in which, for example, a smartphone can be inserted. The magnetic field distribution of the individual components can now also be determined over time. Common errors, such as a defective DC jack, can be quickly and efficiently detected and resolved. Committee is reduced. A complex troubleshooting is then no longer necessary. A suitable algorithm learns to classify the errors and assign the individual objects / devices to these classes.

It can also in all pages, including top and bottom, the measuring box 9 corresponding areal arrays 10 to get integrated. Both the lid or upper side as well as side surfaces and bottom surface can then be used for a spatially resolved determination of the magnetic field. In this way, the spatial distribution of the magnetic fields for each individual inserted into the measuring box device can be detected. The measurement data are divided into classes, for example reference, defect A, defect B etc.

7 shows an example of a measurement result of a measurement of the magnetic field component By as a function of the location over a two-dimensional portion (.DELTA.x, .DELTA.y) of the surface of a component having three parallel current-carrying conductor. From this two-dimensional measurement of the magnetic field component, the course and the correct function of the three conductors can be recognized very well.

With the proposed method and the associated device can also be a time-dependent continuous control of safety-related components. The device continuously records the state of a device and transmits the data to a platform that the user can view. A routine then automatically reports critical conditions. This can be done for example via a corresponding device with sensors, minicomputers and communication electronics such as Wifi, Bluetooth or GSM.

Due to the spatially resolved detection, the method and the device also make it possible to determine not only the two-dimensional, but also the three-dimensional location of a defect. For this purpose, for example, a triangulation based on the magnetic fields measured by a plurality of spatially separated magnetic fields can be made in order to enable a depth and position determination of defects.

With the method and the device can be next to live conductors, for example, in the power electronics and solder connectors analyze the measured magnetic fields.

LIST OF REFERENCE NUMBERS

1

magnetic field sensor

2

carrier

3

Components of the measuring unit

4

Metallic interlayer

5

plug-in elements

6

device

7

conveyor belt

8th

handle

9

bikes

10

measuring box

11

Flat array of magnetic field sensors

Claims (16)

Method for detecting defects in electrical components or assemblies, in which a scanning device with a plurality of magnetic field sensors (1) is used, with which magnetic field components can be detected in three mutually perpendicular spatial directions, the magnetic field components in the three mutually perpendicular spatial directions are measured and recorded as a function of the location during a current flow through the electrical component or module to be measured with the scanning device at a constant distance of the magnetic field sensors (1) to a surface of the electrical component or assembly to be measured, and - The recorded magnetic field components are at least partially evaluated to detect defects in the electrical component or assembly. Method according to Claim 1 , characterized in that the scanning device comprises at least one line-shaped array of magnetic field sensors (1), wherein the magnetic field components in the three mutually perpendicular spatial directions by movement of the linear array of Magnetic field sensors (1) are measured and recorded at a constant distance to the surface of the electrical component or assembly to be measured as a function of the location. Method according to Claim 1 or 2 , characterized in that the magnetic field components recorded as a function of location are compared with reference data representing magnetic field components of a faultless specimen of the electrical component or assembly recorded as a function of the location. Method according to one of Claims 1 to 3 , characterized in that the magnetic field components recorded as a function of the location are fed as measurement data into a cloud-based evaluation system, in which the measurement data are classified and evaluated by a neural network. Method according to Claim 4 , characterized in that the neural network assigns the measurement data due to their classification to errors or error groups. Method according to one of Claims 1 to 5 , characterized in that upon detection of a defect localization of the defect from the recorded magnetic field components by means of triangulation. Method according to one of Claims 1 to 6 , characterized in that the current flow through the electrical component or assembly to be measured in terms of current direction and / or current is varied to gain by the measurement of magnetic field components at different current directions and / or currents further information about defects in the electrical component or assembly. Device for carrying out the method according to one of the preceding claims, comprising at least one line or area array of magnetic field sensors (1), which are arranged on a first side of a carrier (2) and with which magnetic field components in three mutually perpendicular spatial directions are detectable, and a Measuring unit (3) which is arranged on a first side opposite the second side of the carrier (2) and by the magnetic field sensors (1) the magnetic field components in the three mutually perpendicular spatial directions as a function of the location can be measured and recorded, in the carrier (2) between the first and the second side at least one metallic intermediate layer (4) is integrated, by which a shielding of the magnetic field sensors (1) against electromagnetic radiation of the measuring unit (3) is achieved. Device after Claim 8 characterized in that it comprises a means for location or displacement detection, during a relative movement of the linear array of magnetic field sensors (1) relative to an electrical component or assembly to be measured, a determination of a relative position of the linear array of magnetic field sensors (1) over a Surface of the electrical component or assembly allows. Device after Claim 9 , characterized in that it comprises one or more spacers (9), which during the movement of the linear array of magnetic field sensors (1) allows the maintenance of a constant distance of the magnetic field sensors (1) to the surface of the electrical component or assembly to be measured. Device after Claim 9 or 10 , characterized in that it comprises a handle (8) with which it can be manually moved relative to the electrical component or assembly to be measured. Device according to one of Claims 8 to 11 , characterized in that the carrier (2) has connecting elements, via which a plurality of the carriers (2) with the linear or planar array of magnetic field sensors (1) and the measuring unit (3) are electrically and mechanically interconnected. Device after Claim 12 , characterized in that the connecting elements are plug connectors (5). Device after Claim 8 , characterized in that it has a plurality of planar arrays (11) of magnetic field sensors (1) and is designed as a measuring box (10) into which the electrical components or assemblies or devices to be measured with these components or assemblies for the measurement can be inserted, wherein the planar arrays (11) of magnetic field sensors (1) are integrated into one or more sides of the measuring box (10). Device according to one of Claims 8 to 14 , characterized in that it comprises a transmission module for the wireless transmission of magnetic field components measured with the magnetic field sensors (1) as a function of location as measurement data to an external data processing unit or a cloud-based evaluation system. Device according to one of Claims 8 to 15 , characterized in that it comprises a detection module which is connected to the measuring unit (3) and allows detection or readout of an attached to an electrical component or assembly to be measured marking, wherein the measuring unit (3) via the detection module, the identification of the can capture and record to measured or just measured electrical component or assembly.

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