CN114636727A

CN114636727A - Method for detecting inclusions in a fill-in medium of a micromechanical sensor and sensor system

Info

Publication number: CN114636727A
Application number: CN202111543998.6A
Authority: CN
Inventors: D·蒂森; M·克莱茵
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-12-16
Filing date: 2021-12-16
Publication date: 2022-06-17
Also published as: DE102020216003B3

Abstract

A method 100, 200 for detecting inclusions 340 in a fill medium 330 of a micromechanical sensor 305 and a sensor system 300 comprising the micromechanical sensor are presented. The method comprises the following steps: providing 105, 205 a micromechanical sensor 305 having a sensor element 315 arranged in a housing 325 comprising a filling medium 330, which surrounds the sensor element and/or an adjoining heating structure 310; during a heating time t, thermal energy Q is fed in by means of the heating arrangement, the filling medium acting as a heat conductor for the sensor element in the first operating mode 301, and the inclusions 340 in the filling medium are detected in such a way that: a warming T of the micromechanical sensor based on said thermal energy is detected, wherein the inclusion in the second operation mode 302 of the filling medium causes the thermal capacity of the micromechanical sensor to be changed with respect to an inclusion-free condition.

Description

Method for detecting inclusions in a fill medium of a micromechanical sensor and sensor system

Technical Field

The invention relates to a method for detecting inclusions in a filling medium of a micromechanical sensor. The invention also relates to a sensor system comprising such a micromechanical sensor.

Background

A micromechanical sensor having a filling medium and a heating structure for heating and a method for controlling and/or regulating the heating output of the heating structure are known from the publication DE 102005029841 a 1.

Disclosure of Invention

The object of the present invention is to provide an improved method for detecting inclusions in a filling medium of a micromechanical sensor and an optimized sensor system comprising such a micromechanical sensor.

This object is achieved by the method according to the invention for detecting inclusions in a filling medium of a micromechanical sensor and by the sensor system according to the invention. Further advantageous embodiments of the invention are explained below.

A method for detecting inclusions in a filling medium of a micromechanical sensor and a sensor system are proposed, which comprises a micromechanical sensor for detecting a measurement variable to be sensed and at least one electronic component for detecting a heating of the micromechanical sensor and an adjoining heating structure. The micromechanical sensor comprises a sensor element and an evaluation circuit for signal processing and is designed in particular as a pressure sensor. The sensor element and the evaluation circuit are arranged in a housing, wherein the housing comprises a filling medium which surrounds the sensor element and/or the evaluation circuit and/or an adjoining heating structure and is designed in particular to protect the gel. The at least one electronic component may also be arranged in the housing. The heating structure is designed for feeding thermal energy during a heating time, wherein the filling medium acts as a thermal conductor for the sensor element in the first operating mode. The evaluation circuit is designed to recognize inclusions, in particular air inclusions, in the filling medium in such a way that: warming of the micromechanical sensor occurring on the basis of thermal energy fed during the heating time is detected by means of at least one electronic component. This inclusion in the second operating mode of the filling medium results in a change in the thermal capacity of the micromechanical sensor relative to the inclusion-free condition.

With the proposed method and sensor system, a cost-effective and simple implementation is possible, in particular if a heating structure is already integrated in the micromechanical sensor, which heating structure has not been used up to now for detecting inclusions in the filling medium of the micromechanical sensor. Due to the flexible possibility of mounting the heating structure on the micromechanical sensor or in the housing of the micromechanical sensor itself, a subsequent retrofitting or expansion of the heating structure can also be achieved without great effort. The proposed method together with the sensor system can be used on the one hand during the production process of the micromechanical sensor (for example in End-of-Line (End-of-Line) control in production) and can be used to detect inclusions in the filling medium. The invention therefore provides an advantageous alternative to costly and time-consuming screening methods (Screeningverfahren), which are carried out, for example, by means of X-ray analysis or acoustic scanning microscopy. On the other hand, the method can also be used to identify possible performance deviations when using micromechanical sensors in various customer-specific terminals. Without the proposed invention, this check cannot be realized or can only be realized with great difficulty.

The proposed invention advantageously exploits the following facts: the materials of the evaluation circuit, of the sensor element, of the filling medium and possibly of other components arranged in the micromechanical sensor housing each have a specific thermal capacitance when they are heated by means of the heating structure. The sum of which, for example, forms the thermal capacity of the micromechanical sensor in proportion to the weight. With the inclusion of, for example, air inclusions in the filling medium, which is preferably designed as a protective gel, the heat capacity of the components mentioned changes during the heating by means of the heating structure. The change in the heat capacity or the deviation between the reference heating and the actual heating of the micromechanical sensor can then be used in a targeted manner to determine the presence of inclusions. The micromechanical sensor can advantageously be designed in the form of a pressure sensor, wherein the sensor element then corresponds to the pressure-sensitive membrane and the measured variable to be sensed corresponds to the external pressure acting on the membrane. The membrane may hermetically close the cavity with a vacuum.

In a further embodiment, the detection of inclusions in the filling medium by the evaluation circuit comprises comparing the heating of the micromechanical sensor with a reference heating detected by means of a further sensor on the basis of the thermal energy fed in during the heating time. Furthermore, the detection of inclusions in the filling medium by the evaluation circuit comprises determining the presence of inclusions if a deviation occurs between the heating of the micromechanical sensor and the reference heating. In an advantageous manner, no additional components are therefore required, since the evaluation circuit, which may be implemented as an ASIC, for example, takes over the signal processing and can detect such inclusions in the filling medium according to the above-mentioned criteria. In particular, the reliability of the proposed micromechanical sensor can be improved in this way, or a faster "error finding" (fehlesuche) in the case of sensors that are damaged due to inclusions can be facilitated. The comparability of the heating of the micromechanical sensor to the reference heating can be obtained here, for example, in the following manner: the same or similar conditions, such as heating power and measurement time, are selected for the different measurements.

In another embodiment, the determination of inclusions by the evaluation circuit further comprises the identification of a deviation between the heating of the micromechanical sensor and the reference heating by: a status report is assigned to the detected warming of the micromechanical sensor. The assigned status report can be identified, for example, as a faulty value or, in general, as a faulty micromechanical sensor. For example, the measured value can be "marked (geflag)", i.e. identified as faulty in an internal memory of the micromechanical sensor, which can be included, for example, by the evaluation circuit. It is conceivable that, if the evaluation circuit comprises a microcontroller, for example, the microcontroller can perform such a marking or identification by means of a status report. The identification can also be carried out by means of application software or an external data processing unit in the corresponding terminal device.

In another embodiment, to detect reference warming, calibration is performed based on multiple micromechanical sensors of the same type. For this calibration, reference warmings of the micromechanical sensors are determined for each of the micromechanical sensors of the same type. The proposed invention offers a high degree of flexibility, since the calibration of the heating of the micromechanical sensor can be carried out in various ways during the heating process by means of the heating structure, wherein the heating is then configured as a reference heating and can therefore be adapted as well as possible to the system and application requirements. In this embodiment, the calibration is carried out by means of the collective behavior of a plurality of micromechanical sensors of the same type, wherein the sensors can all be embodied, for example, as pressure sensors of the same type. Such a calibration can then advantageously be performed once, for example based on a study of 1000 pressure sensors of the same model.

In another embodiment, to detect reference warmth, calibration is performed based on a micromechanical sensor. For this calibration, reference warmings of the micromechanical sensor are determined at regular time intervals. The proposed invention offers a high degree of flexibility, since the calibration of the heating of the micromechanical sensor can be carried out in various ways during the heating process by means of the heating structure, wherein the heating is then configured as a reference heating and can therefore be adapted as well as possible to the system and application requirements. In this configuration, the calibration is carried out by means of an individualized behavior of the individual micromechanical sensors, wherein the sensors may be embodied, for example, as pressure sensors. Such a calibration can then advantageously be carried out over a longer period of time, for example over the entire year, and the reference warming of the micromechanical sensor can be detected at regular intervals, for example daily. Alternative time intervals and calibration periods are also possible.

In a further embodiment, the heating of the micromechanical sensor and the reference heating are each temperature variables. The temperature variable may be, for example, a directly measured temperature, which is detected by means of at least one electronic component. In this case, for example, at least one electronic component can likewise be integrated in the housing of the micromechanical sensor and operatively connected to the evaluation circuit. Alternatively, the evaluation circuit can also have at least one electronic component, for example, which is designed to detect the heating and reference heating of the micromechanical sensor. The at least one electronic component can be designed, for example, as a sensor. Furthermore, the temperature variable may also be an indirectly measured temperature, for example by means of a voltage or current signal which is proportional to the heating, i.e. the sensor temperature, and may be detected by means of at least one electronic component which is designed, for example, in the form of a capacitance/capacitor, a resistor and/or a substitute component which enables an indirect temperature measurement.

In a further embodiment, the heating structure is arranged on a surface of an evaluation circuit of the micromechanical sensor and the sensor element is arranged on a surface of the heating structure. Alternatively, the sensor element is arranged on a surface of the evaluation circuit and the heating structure is arranged on a surface of the sensor element. This results in a compact design of the micromechanical sensor as a whole, since the heating structure can be arranged flexibly and can be arranged not only in the housing, i.e. adjacent to the filling medium or adjacent to the sensor element and/or the evaluation circuit, but also outside the housing. Such a variable placeability of the heating structure can, depending on the placement, particularly advantageously act on the heating time and/or heating power used and can thus, for example, reduce the required measuring time.

In another embodiment, the housing has at least one side wall and a bottom region. The carrier element forms a base region, wherein the carrier element is designed in particular as a printed circuit board. The heating structure is at least partially adjacent to the side wall and/or to the carrier element. This results in a compact design of the micromechanical sensor as a whole, since the heating structure can be arranged flexibly and can be arranged not only in the housing, i.e. adjacent to the filling medium or adjacent to the sensor element and/or the evaluation circuit, and/or can be adjacent to the side wall and/or the carrier element within the housing, but also outside the housing. Depending on the placement, such a variable placeability of the heating structure can in particular advantageously have an effect on the heating time and/or heating power used and can thus, for example, reduce the required measuring time.

The advantageous configurations and embodiments of the invention described above and/or reproduced in the advantageous embodiments can be used alone or in any combination with one another, except, for example, in the case of only explicitly relevant or incompatible alternatives.

Drawings

The above features, characteristics and advantages of the present invention and the manner and method of attaining them will become more apparent and readily appreciated in connection with the following description of the embodiments set forth in greater detail in connection with the accompanying drawings. The figures show:

fig. 1a shows a schematic view of a method for detecting inclusions in a filling medium of a micromechanical sensor according to a first embodiment;

fig. 1b shows a schematic illustration of a first embodiment of the method for detecting inclusions in a filling medium of a micromechanical sensor according to fig. 1 a;

fig. 1c shows a schematic illustration of a second embodiment of the method for detecting inclusions in the filling medium of a micromechanical sensor according to fig. 1 a;

fig. 1d shows a schematic view of a method for detecting inclusions in a filling medium of a micromechanical sensor according to a second embodiment;

fig. 1e shows a schematic illustration of a first embodiment of the method for detecting inclusions in the filling medium of a micromechanical sensor according to fig. 1 d;

fig. 2a and 2b show schematic diagrams of a sensor system comprising a micromechanical sensor for implementing the proposed method according to fig. 1a to 1 d;

fig. 2c to 2d and 3 show further schematic views of the micromechanical sensor of fig. 2a and 2 b.

It should be noted that the figures are merely schematic in nature and are not to scale. To this extent, the components and elements shown in the figures may be illustrated in exaggerated or reduced form for better understanding. It is further noted that reference numerals in the figures are selected unchanged if identically constructed elements and/or components are referred to.

Detailed Description

Fig. 1a shows a schematic illustration of a method 100 for detecting inclusions 340 in a fill medium 330 of a micromechanical sensor 305 according to a first embodiment. The method 100 comprises: in a first step 105, micromechanical sensor 305 having sensor element 315 is provided, sensor element 315 being arranged in housing 325 and housing 325 comprising a filling medium 330. The fill medium 330 surrounds the sensor element 315 and/or the adjoining heating structure 310. The method 100 provides in a second step 110 that a heating structure 310 is used to feed thermal energy Q during a heating time t, wherein the filling medium 330 acts as a thermal conductor for the sensor element 315 in the first operating mode 301. In addition, an evaluation circuit 320 can be arranged in housing 325, which can be embodied, for example, as an ASIC, wherein in first operating mode 301 filling medium 330 also acts as a heat conductor for evaluation circuit 320 and/or other components of micromechanical sensor 305 present in housing 325. In a third step 115 of the method 100, inclusions 340, in particular air inclusions, in the filling medium 330 are identified by: the warming that occurs by the micromechanical sensor 305 on the basis of the thermal energy Q fed during the heating time t is detected.

The inclusion 340 in the second operating mode 302 of the filler medium 330 causes the thermal capacity of the micromechanical sensor 305 to be changed relative to the situation without the inclusion 340. The thermal capacity of the micromechanical sensor 305 can be calculated here, for example, by adding the individual specific heat capacities of the materials used for the components of the micromechanical sensor 305. The individual components of the micromechanical sensor 305 are subsequently explained on the basis of fig. 2a to 2d and fig. 3.

Fig. 1b shows a schematic illustration of a first embodiment of the method 100 for detecting an inclusion 340 in a fill medium 330 of a micromechanical sensor 305, which has been illustrated in fig. 1 a. Here, the third step 115 of fig. 1a comprises identifying inclusions 340, now comprising the first sub-step 120 and the second sub-step 125. The first sub-step 120 comprises a step of bringing the warming T of the micromechanical sensor 305 to a reference warming T that occurs on the basis of the thermal energy Q fed during the heating time T that is detected₀A comparison is made. The second substep 125 comprises: if the temperature T of the micromechanical sensor 305 is equal to the reference temperature T₀If there is a deviation therebetween, it is determined that there is an inclusion 340.

Fig. 1c shows a schematic illustration of a second embodiment of the method 100 in fig. 1a for detecting an inclusion 340 in the filling medium 330 of the micromechanical sensor 305. In a second embodiment in fig. 1c, the second substep 125 in fig. 1b comprises a third substepAnd a substep 130. That is, the determination of the inclusion 340 further includes a warming T of the micro-mechanical sensor 305 and a reference warming T₀The deviation between them is identified by: a status report is assigned to the detected warming T of the micromechanical sensor 305. The status report can be implemented, for example, as a so-called flag and integrated in the internal memory of the micromechanical sensor 305 and, for example, identifies a detection value of the warming T of the micromechanical sensor 305 as faulty. It is also conceivable to apply a status report to the entire micromechanical sensor 305 and to identify the micromechanical sensor 305 as faulty, for example.

The identification mentioned can be implemented at the end client, for example by means of application software, or alternatively also in the analysis processing circuit if it comprises a microcontroller, for example. Mentioned and reference warmings T of the micromechanical sensor 305₀For example, each of the temperature sensors is designed as a temperature variable, wherein the temperature variable may correspond to a directly measured temperature or an indirectly measured temperature, for example a temperature measured by means of at least one electronic component by means of a voltage signal or a current signal. Alternative configurations are also contemplated herein.

Fig. 1d shows a schematic illustration of a method 200 for detecting inclusions 340 in a fill medium 330 of a micromechanical sensor 305 according to a second embodiment. The first step 205 may be configured here, for example, analogously to the first step 105 of the method 100 in fig. 1a to 1 c. Likewise, the second step 210 may be configured similarly or identically to the second step 110 in the method 100, and therefore reference is made to the above description for

steps

205 and 210. In contrast to fig. 1a to 1c and the method 100 shown therein, the method 200 in fig. 1d can provide a third step 215, i.e. for example a calibration, which is carried out to detect a reference warm-up T for the micromechanical sensor 305₀. The calibration in the third step 215 may, for example, advantageously already be carried out beforehand, so that in the method 200 only the calibration result may be used in the third step 215.

The fourth step 220 in fig. 1d, which follows this, can for example correspond to the third step 115 in fig. 1a to 1c, i.e. the identification of the inclusion 340. The first sub-step 225 and the second sub-step in fig. 1dStep 230 may be constructed, for example, similarly to first substep 120 and second substep 125 in fig. 1 b. That is, the warming T of the micromechanical sensor 305 may be compared to the reference warming T generated based on the thermal energy Q fed during the heating time T detected in the third step 215₀Compare and if at a warm T with a reference warm T₀If there is a deviation therebetween, it can be determined that there is a possible inclusion 340. The method 200 in fig. 1d is exemplary and may also comprise or be combined with further method steps, as shown in fig. 1a to 1c, without detracting from the invention.

Fig. 1e shows a schematic illustration of a first embodiment of the method 200 from fig. 1d for detecting inclusions 340 in the fill medium 330 of the micromechanical sensor 305. The first embodiment relates to a third step 215 in fig. 1d, namely the calibration of the micromechanical sensor 305. For detecting reference warming T of micromechanical sensor 305₀The calibration performed may be performed, for example, in different ways. Thus, in branch 235 in fig. 1e, it is checked whether calibration should be performed based on multiple micromechanical sensors 305 of the same type. In the case of a positive check, indicated by the "y" branch in fig. 1e, the reference warmings T of the micromechanical sensors 305 are respectively determined for a plurality of micromechanical sensors 305 of the same type in a third substep 240 for calibration purposes₀. If the micromechanical sensor 305 is designed as a pressure sensor, for example, the reference temperature T of a plurality of pressure sensors of the same type and model, for example a number of 1000 sensors, can be determined by means of the proposed calibration₀. The collective behavior of pressure sensors of the same type can thus be studied and used for calibration and advantageously performed once.

In the case of a negative check result of branch 235, indicated by the "n" branch in fig. 1d, in a fourth substep 245 based on the determined reference warming T of the individual micromechanical sensor 305₀A calibration is performed. For calibration purposes, the reference warming T of the individual micromechanical sensors 305₀And therefore are evaluated at regular intervals (e.g., daily) over a longer period of time (e.g., a year). I.e. in the fourth substep 245For calibration, the individualized behaviour of the individual micromechanical sensors 305 is considered. Here, micromechanical sensor 305 may be configured as a pressure sensor, as described above. The method 200 in fig. 1d and 1e can be applied in the same way to the method 100 shown in fig. 1a to 1c and is not limited to the exemplary illustration. For example, the calibration may be performed under laboratory conditions, i.e. at a reference temperature of 25 ℃ (room temperature) and a reference pressure of 980 mbar.

Fig. 2a and 2b show a schematic representation of a sensor system 300 comprising a micromechanical sensor 305, which is suitable for carrying out the method according to fig. 1a to 1 d. The sensor system 300 comprises a micromechanical sensor 305 and an adjoining heating structure 310, wherein the heating structure 310 in fig. 2a and 2b is, for example, integrated in the micromechanical sensor 305. Micromechanical sensor 305 includes a sensor element 315 for detecting a measurement variable to be sensed and an evaluation circuit 320, which are operatively connected to one another. If micromechanical sensor 305 is configured as a pressure sensor, sensor element 315 comprises, for example, a pressure-sensitive membrane for detecting an external pressure. The sensor element 315 of the pressure sensor, which is embodied as a pressure-sensitive membrane, can seal the cavity, for example, in a vacuum and is not shown in the figure, which shows a simple schematic illustration of the micromechanical sensor 305. The filling medium 330 serves in particular here to transmit pressure from the surroundings to the membrane of the sensor element 315.

The sensor element 315 and the evaluation circuit 320, which is embodied for example in the form of an ASIC, are arranged for example in a housing 325 of the micromechanical sensor 305. The housing 325 includes a fill medium 330 configured to, among other things, protect the gel and thus the micromechanical sensor 305 from environmental or mechanical influences such as moisture, particles, or chemicals. Because the filling medium 330 is used in the micromechanical sensor 305, in particular in direct contact with the mentioned environmental influences. In the illustration of fig. 2a and 2b, the filling medium 330 surrounds, for example, the sensor element 315, the evaluation circuit 320 and the heating structure 310 adjacent to the sensor element 315. The sensor system 300 may, for example, have at least one sensor for detecting a reference warming T in FIG. 2a₀Or the electrons used to detect a warm-up T in FIG. 2bComponent 335, wherein in these illustrations at least one electronic component 335 is not arranged in housing 325 of micromechanical sensor 305, but is communicatively or operatively connected to evaluation circuit 320 and is configured, for example, as an external sensor.

Alternatively, however, it is conceivable to integrate at least one electronic component 335 into the housing 325 of the micromechanical sensor 305, so that the at least one electronic component 335 is likewise surrounded by the filling medium 330. In this alternative configuration, the at least one electronic component 335 may also be configured as a sensor. Furthermore, the at least one electronic component 335 can be designed, for example, as a capacitor, a resistor, or the like, and can be indirectly temperature-measured by means of a voltage signal or a current signal that is proportional to the heating, i.e., the heating, temperature of the micromechanical sensor 305. Furthermore, the analysis processing circuit 320 may comprise at least one electronic component 335, for example in an integrated manner. The heating structure 310 is designed for feeding thermal energy Q to the micromechanical sensor 305 during a heating time t, for example, in order to bring the micromechanical sensor 305 to an operating temperature different from a room temperature of 25 ℃, for example. Shown in fig. 2a is a first operating mode 301 of the filling medium 330, in which operating mode the filling medium 330 acts as a heat conductor for the sensor element 315 and the evaluation circuit 320. For example, in fig. 2a the reference heating T detected with at least one electronic component 335 without inclusions in the filling medium 330 of the micromechanical sensor 305₀A temperature rise of 20 kelvin or 20 ℃ of the micromechanical sensor 305, which occurs by feeding thermal energy Q via the heating structure 310 during the heating time t, may be caused.

For example, the dimension of the heating structure 310 is about 0.1mm²And a heating time t of 10 seconds, the mentioned temperature rise of 20 kelvin or 20 ℃ can be achieved. In the case of deviations from this of the dimensions of the heating structure 310 and/or deviations from this of the position of the heating structure 310, other heating times t or other heating powers can also be taken into account and thus other values of the temperature rise can be obtained. Furthermore, the corresponding heating time t is limited by the heating power used. The evaluation circuit 320 is designed in fig. 2b for the purpose of identifying, in particularAir-entrained inclusions 340 may be formed in the fill media 330 by: by means of the at least one electronic component 335, the warming T of the micromechanical sensor 305 occurring on the basis of the thermal energy Q fed by the heating structure 310 during the heating time T is detected. This may be done, for example, by recording a heating profile that may account for the characteristic heating of the micromechanical sensor 305 for a given heating power.

In this case, the inclusions 340 in fig. 2b act in the second operating mode of the filler medium 330 in such a way that the thermal capacity of the micromechanical sensor 305 is changed in relation to the situation in fig. 2a in which no inclusions are present. Due to the varying heat capacity, the temperature characteristics of the micromechanical sensor 305 also change when thermal energy Q is fed by means of the heating structure 310. If the sensor 305 is designed as a pressure sensor, the filling medium 330 in the second operating mode 302 has, in particular, a biased mechanical behavior under pressure and temperature variations, which leads to an error in the pressure value to be detected of the pressure sensor, due to a change in contact with the pressure-sensitive sensor element 315 caused by the inclusion 340.

The evaluation circuit 320 is designed in particular for comparing the heating T of the micromechanical sensor 305 with a reference heating T, which is detected in fig. 2a by means of at least one electronic component 335 and which occurs on the basis of the thermal energy Q fed in during the heating time T₀A comparison (i.e. a comparison of the two heating profiles) is made (e.g. in the form of another heating profile detected). If the temperature T of the micromechanical sensor 305 is equal to the reference temperature T₀If there is a deviation therebetween, the analysis processing circuit 320 can determine that there is an inclusion 340. For example, a deviation in the presence of an inclusion 340 in the filling medium 330 can result in a deviation of 2 times the operating temperature of the micromechanical sensor 305, i.e. where a temperature increase of 20 kelvin or 20 ℃ could previously be detected, for example, without an inclusion 340, the value now increases by a factor of 2 in the presence of an inclusion 340. Then, in the mentioned example, the deviation would comprise 20 kelvin or 20 ℃. If T is warmed or reference T is warmed₀Plotted separately as a heating curve, the heating curve can be compared to a reference, for example, in the presence of inclusions 340The curves deviate and describe completely different curve profiles. Alternatively, a computer simulation can be considered, which can be used in order to find the mentioned deviations. In order to warm up T with respect to the detected reference₀Calibration is carried out, making use of the variant shown in fig. 1e, and reference is therefore made to the above description.

Fig. 2c and 2d and fig. 3 are further schematic views of the micromechanical sensor 305 of fig. 2a and 2 b. The micromechanical sensors 305 in fig. 2c and 2d and fig. 3 can also each be designed as a pressure sensor as described above. For example, fig. 2c, 2d and 3 show the situation in which there are inclusions 340, i.e. the second mode of operation 302 of the filling medium 330, respectively. In contrast to the previous figures, the heating structure 310 in fig. 2c is arranged on the surface of the

evaluation circuits

350, 320 of the micromechanical sensor 305. For example, the heating structure 310 may cover approximately one third of the surface of the

analytical processing circuit

350, 320. The sensor element 315 is in turn arranged on a surface 355 of the heating structure 310. Additionally, bond wires 345 for electrically contacting the sensor elements 315 are drawn in fig. 2 c. Bonding wires 345 or other bonding wires not shown can also be used to turn on the heating structure. Fig. 2d shows an alternative configuration to fig. 2c, in which the sensor element 315 in fig. 2d is arranged on a surface 350 of the evaluation circuit 320. The heating structure 310 is arranged on a surface 360 of the sensor element 315.

In contrast to fig. 2a to 2d, the micromechanical sensor 305 in fig. 3 has a plurality of heating structures 310, the positions of which deviate from the previous figures. The housing 325 in fig. 3 has a first sidewall 365 and a second sidewall 370 and a bottom region 375. It is understood that first side wall 365 and second side wall 370 each form only a surrounding wall in the three-dimensional configuration of micromechanical sensor 305, which is not shown in fig. 3. Thus, the present invention is not limited to the schematic diagram in fig. 3. The carrier element 377 forms a base region 375, wherein the carrier element 377 can be designed, for example, as a printed circuit board.

For example, the heating structure may be double configured 380 such that the heating structure abuts not only the inner sidewall 385 of the first sidewall 365 but also the outer sidewall 390 of the first sidewall 365. Further, the heating structure 310 may, for example, abut an inner sidewall 392 of the second sidewall 370 of the housing 325. In addition, the heating structure 310 may also be adjacent to the outer sidewall 394 of the bottom region 375. However, with the proposed invention, the heating structure 310 does not necessarily have to have the structure shown in fig. 3, but can also be implemented in a configuration deviating from this. Fig. 3 is therefore intended to depict only schematically which installation possibilities are conceivable for the heating structure 310 on the micromechanical sensor 305 or in the micromechanical sensor 305. For example, the heating structure 310 adjacent to the outer side wall 394 of the base region 375 can also be formed in one piece and offset from the dimensions of the heating structure 310 on the inner side wall 392 of the second side wall 370, wherein the offset dimensions can then lead to an offset heating output or heating time in order to correspondingly warm the micromechanical sensor 305 by feeding thermal energy Q. In particular, commonly used materials can be used for the micromechanical sensor 305 and the micromechanical sensor 305 itself can be manufactured by means of MEMS technology (micro-electromechanical systems technology). The mentioned heating power of the heating structure 310 may be largely dependent on the respective application.

With the structure of the heating structure 310 shown in fig. 3, it is also conceivable to determine the position of the inclusions 340 by selective heating of the heating structure 310 if, for example, the heating structure 310 is mounted at four different locations on or in the housing 325 of the micromechanical sensor 305, namely on the

side walls

365, 370 and in the bottom region 375, and then only one heating structure 310 at a specific location is operated in each case. And then may gradually transition to operating the corresponding next heating structure 310 at a different location. Furthermore, if the

methods

100, 200 are performed prior to the curing process of the fill medium 330, the inclusions 340 may have been identified and removed during the manufacturing process. It is no longer possible to remove the inclusions 340 afterwards.

The present invention has been described in detail through preferred embodiments. Instead of the described embodiments, other embodiments are conceivable which may have other modifications or combinations of the features described. For this reason, the invention is not limited to the examples disclosed, since further modifications can be derived therefrom by those skilled in the art without departing from the scope of the invention.

List of reference numerals

100 method according to the first embodiment

105 first step

110 second step

115 third step

120 first substep

125 second substep

130 third substep

135 fourth step

200 method according to the second embodiment

205 first step

210 second step

215 third step

220 fourth step

225 first substep

230 second substep

Branch 235

240 third substep

245 fourth substep

300 sensor system

301 first mode of operation

302 second mode of operation

305 micromechanical sensor

310 heating structure

315 sensor element

320 analysis processing circuit

325 shell

330 filling medium

335 electronic component

340 is mingled with

345 bonding wire

350 analyzing the surface of a processing circuit

355 heating the surface of the structure

360 surface of sensor element

365 first side wall

370 second side wall

375 bottom region

377 Carrier element

380 double heating structure

385 inner side wall of first side wall

390 outer side wall of the first side wall

392 inner side wall of the second side wall

394 outside wall of the bottom region

time of heating

Q heat energy

T warming

T₀Reference warming

Claims

1. A method (100, 200) for detecting inclusions (340) in a fill medium (330) of a micromechanical sensor (305), the method comprising the steps of:

providing (105, 205) a micromechanical sensor (305) having a sensor element (315), wherein the sensor element (315) is arranged in a housing (325) and the housing (325) comprises a filling medium (330) which surrounds the sensor element (315) and/or an adjoining heating structure (310),

feeding thermal energy (Q) by means of the heating structure (310) during a heating time (t), wherein the filling medium (330) acts as a thermal conductor (110, 210) for the sensor element in a first operating mode (301), and

-identifying (115, 220) inclusions (340), in particular air inclusions, in the filling medium (330) by: detecting a heating (T) of the micromechanical sensor (305) occurring based on thermal energy (Q) fed during the heating time (T),

wherein the inclusion (340) causes a thermal capacitance of the micromechanical sensor (305) to be changed relative to an inclusion-free condition in the second mode of operation (302) of the fill medium (330).

2. The method (100, 200) of claim 1,

wherein the identifying (115, 220) of the inclusion (340) in the fill medium (330) further comprises:

comparing (120, 225) the heating (T) of the micromechanical sensor (305) with a reference heating (T) detected on the basis of the thermal energy (Q) fed during the heating time (T)₀) And are and

if the temperature (T) at the micromechanical sensor (305) is equal to the reference temperature (T)₀) If there is a deviation between them, it is determined (135, 230) that an inclusion (340) exists.

3. The method (100, 200) of claim 2,

wherein the determining (135) of the inclusion (340) further comprises:

identifying (135) the heating (T) of the micromechanical sensor (305) with the reference heating (T)₀) The deviation between them is in the following way: assigning a status report to the detected warming of the micromechanical sensor.

4. The method (100, 200) of claim 2 or 3,

wherein for warming the reference (T)₀) Detecting, performing (235) a calibration based on a plurality of micromechanical sensors of the same type,

wherein for the calibration, reference warmings of the micromechanical sensors (305) are respectively determined (240) for the plurality of micromechanical sensors of the same type.

5. The method (100, 200) of claim 2 or 3,

wherein, in order to detect the reference heating (T)₀) Performing a calibration based on the micromechanical sensor (305),

wherein the reference heating (T) of the micromechanical sensor (305) is determined at regular time intervals for the calibration₀)。

6. The method (100, 200) according to any one of claims 1 to 5,

wherein the heating (T) and the reference heating (T) of the micromechanical sensor (305)₀) Respectively, are temperature parameters.

7. A sensor system (300), comprising:

a micromechanical sensor (305) and an adjoining heating structure (310), wherein the micromechanical sensor (305) comprises a sensor element (315) for detecting a measurement variable to be sensed and an evaluation circuit (320) and is in particular designed as a pressure sensor,

wherein the sensor element (315) and the evaluation circuit (320) are arranged in a housing (325) and the housing (325) comprises a filling medium (330) which surrounds the sensor element (315) and/or the evaluation circuit (320) and/or the adjoining heating structure (310) and is in particular designed as a protective gel,

-at least one electronic component (335) for detecting a heating (T) of the micromechanical sensor (305),

wherein the heating structure (310) is designed for feeding thermal energy (Q) during the heating time (t), wherein the filling medium (330) acts as a thermal conductor for the sensor element (315) and/or the evaluation circuit (320) in a first operating mode (301), and

wherein the evaluation circuit (320) is designed to detect inclusions (340), in particular air inclusions, in the filling medium (330) by: detecting, by means of the at least one electronic component (335), a heating (T) of the micromechanical sensor (305) occurring on the basis of thermal energy (Q) fed during the heating time (T),

8. The sensor system (300) of claim 7,

wherein the evaluation circuit (320) is further designed for comparing the heating (T) of the micromechanical sensor (305) with a reference heating (T) occurring using the at least one electronic component (335) and being detected on the basis of the thermal energy (Q) fed in during the heating time (T)₀) Making a comparison, and

wherein the evaluation circuit (320) is designed to evaluate the temperature (T) of the micromechanical sensor (305) if the temperature (T) is equal to the reference temperature (T)₀) If there is a deviation, it is judged that there is a gap (340).

9. The sensor system (300) of claim 7 or 8,

wherein the heating structure (310) is arranged on a surface (350) of an evaluation circuit of the micromechanical sensor (305), and

wherein the sensor element (315) is arranged on a surface (355) of the heating structure, or,

wherein the sensor element (315) is arranged on a surface (350) of the evaluation circuit, and

wherein the heating structure (310) is arranged on a surface (360) of the sensor element.

10. The sensor system (300) of any of claims 7 to 9,

wherein the housing (325) has at least one side wall (365, 370) and a bottom region (375),

wherein a carrier element (377) forms the base region (375), wherein the carrier element (377) is designed in particular as a printed circuit board, and

wherein the heating structure (310) is at least partially adjacent to the at least one side wall (365, 370) and/or to the carrier element (377).