Flow-sensor package

Abstract

The invention relates to a sensor package comprising a sensor chip for measuring at least one flow parameter of a fluid and also comprising a base plate and a covering. The sensor package has openings on the covering and / or the base plate, for providing an entry region and an exit region for the fluid, such that a flow channel is formed within the sensor package. Furthermore, the sensor chip has a thermal sensor, comprising a heating element for providing a thermal field and also comprising a sensor component for detecting a temperature response of the thermal sensor in dependence on an influence which the fluid flowing in the flow channel has on the thermal field. On an outer side of the sensor package, at least one opening is laterally enclosed by a sealing material. The invention also relates to a sensor-package assembly, to a system and to a use of the sensor-package assembly or of the system.

Description

[0001] FLOW SENSOR PACKAGE

[0002] DESCRIPTION

[0003] The invention lies in the technological field of MEMS flow sensors. The invention relates to a sensor package comprising a sensor chip for measuring at least one flow parameter of a fluid, a base plate, and a cover. The sensor package has openings on the cover and / or the base plate for providing an inlet region and an outlet region for the fluid, so that a flow channel is formed within the sensor package. Furthermore, the sensor chip has a thermal sensor comprising a heating element for providing a thermal field and a sensor component for detecting a temperature response of the thermal sensor as a function of an influence of the fluid flowing in the flow channel on the thermal field. On an outer side of the sensor package, at least one opening is laterally enclosed by a sealing material.

[0004] Furthermore, the invention relates to a sensor package arrangement, a system and a use of the sensor package arrangement or the system.

[0005] Background and state of the art

[0006] Flow sensors are used in various applications involving flowing fluids and are capable of measuring a fluid's flow parameter. For example, the velocity, flow direction, and / or viscosity of the fluid can be detected using a flow sensor, without being limited to the parameters mentioned above. Typically, the influence of the flow, i.e., the influence resulting from the movement of the fluid, is utilized to perform the measurement by the flow sensor.

[0007] In some applications, it is common to provide a so-called bypass configuration in which a flow parameter of a fluid is measured. In a bypass configuration, a flow restrictor or flow limiter is installed within a main channel through which the fluid flows. The main channel can be, for example, a pipeline for transporting a liquid or within an industrial plant. Furthermore, a bypass (also bypass channel or side channel) is fluidically connected to the main channel. The flow restrictor results in a pressure drop, so that a pressure difference exists in the main channel depending on the flow of the fluid. If the bypass is appropriately connected to the main channel upstream and downstream of the flow restrictor, the fluid is guided into the bypass due to the pressure difference. The sensor used to measure the fluid can be positioned inside or adjacent to the bypass.A bypass configuration ensures reliable fluid transfer in sufficient proximity to the sensor without requiring the sensor to be located in the main channel, which could disrupt the fluid flow. Furthermore, the flow velocity of the fluid in the bypass channel is directly dependent on the pressure difference created in the main channel by the flow restrictor. By measuring the flow velocity of the fluid in the bypass channel, the flow behavior of the fluid in the main channel can also be monitored.

[0008] A proven functional principle for the operation of flow sensors in the state of the art is the thermal measurement principle. The flow sensor typically comprises a heating element and at least one temperature sensor. The heating element generates a thermal field that can be detected by the temperature sensor. When a fluid flows, the thermal field generated by the heating element is modulated. The modulation is detectable by the temperature sensor, with the modulation of the thermal field dependent on the fluid flow. A flow parameter can be determined by modulating the thermal field. The described measurement principle is advantageous in that it eliminates the need for mechanically moving components, thus reducing manufacturing costs and achieving high robustness.

[0009] Using so-called MEMS (microelectromechanical systems), thermal flow sensors can also be provided that have a very compact design (in the micrometer range), excellent functionality, and can be produced at low manufacturing costs.

[0010] As is well known, MEMS devices usually require a platform in the form of a housing for protection and integration into an application. This is also referred to as the MEMS package. The specific design of the package depends on the type of MEMS and the requirements it must meet. These requirements, in turn, are related to the specific application.

[0011] Lee, Ramados & Hoivik (2018) present various variants for the structural design of MEMS packages. Package designs can generally be divided into ceramic, metallic, and plastic packages. A conventional ceramic or metallic package often comprises a base and a cover or cap. The MEMS is mounted on the base, which can also be electrically contacted to the base, for example, using wire bonds. To encapsulate the MEMS, the cover is applied, which covers the MEMS and is connected to the base. The base can be, for example, a conventional semiconductor substrate or a circuit board as a circuit carrier. The cover can, for example, comprise glass, metal, ceramic, or plastic. Whether the package is a ceramic or metallic package is determined primarily by the material selected for the package.A plastic package is essentially made of plastic and can be constructed in one piece or in multiple pieces. Plastic packages can be efficiently geometrically structured before or after the MEMS is inserted using primary forming processes to specify the desired shape for the package.

[0012] Package structures are also relevant for flow sensors. Kuo, Yu & Meng (2012) provides an overview of flow sensors and their packaging based on a thermal measurement principle. For example, polymer substrates with flexible properties that form a section of the flow sensor package are known in the art. This allows the flow sensors to be applied to curved surfaces while still being sufficiently stable to perform flow measurements. In particular, such packages can also detect high flow pressures. Polymer substrates can also be used in biological contexts for the packaging of flow sensors. For example, flexible polymer substrates based on Parylene C are known. These can be used for flow sensors, for example, to measure blood flow within an artery.The polymer substrate is connected to an electrically conductive catheter and implanted into the walls of the artery so that medical examinations can be carried out based on blood flow.

[0013] There are also known approaches to attaching flow sensors to ceramic substrates. These are well suited for enabling stable mounting of components such as thermopiles, heating elements, transistors, etc. The flow sensor can be mounted on the ceramic substrate, while copper pillar bumps are connected to the ceramic substrate. Copper pillar bumps (or simply copper bumps) not only provide electrical functionality but also serve a thermal management function, thus reducing adverse parasitic heat effects.

[0014] Furthermore, it is known, for example, to measure air flow, to design a package such that the actual flow sensor is mounted on a thin circuit board. The circuit board is mounted on a support structure, which may, for example, be made of aluminum, and extends across a gap in the support structure. The support structure, in turn, can be mounted on a holder made of plastic. The air to be measured flows above the actual sensor, i.e., above the circuit board on which the sensor is located.

[0015] Furthermore, approaches for flow sensors are also known in which the flow of a fluid is measured that does not flow directly above or at a sensor structure. For example, a sensor structure can be mounted on a membrane, and the flow can occur below the membrane. In particular, the package can provide a flow channel in which the fluid can flow. The flow channel runs within the package in such a way that the flow can be detected by the flow sensor, allowing conclusions to be drawn about one or more flow parameters of the fluid.

[0016] WO 2021 / 078770 A1, for example, discloses a package having a flow channel for the flow of a fluid. The package comprises at least two substrates that are connected to one another. The first substrate can be provided by a semiconductor substrate and comprises a cavity. The second substrate essentially forms the flow channel. Preferably, an inlet and an outlet for the fluid are present on the second substrate. The second substrate comprises a shape adaptation with respect to the cavity of the first substrate and can preferably be formed by a preformed plastic. Furthermore, a thermal sensor is present on a dielectric layer that adjoins the cavity of the first substrate. An electrical connection to the thermal sensor is enabled via bumps that are arranged between the dielectric layer and a circuit board.In preferred embodiments, a further third substrate can also be provided, which can in particular be provided as a preformed plastic and can be attached to the second substrate to provide an inlet and outlet for the fluid. Disadvantages of using preformed plastic materials are tolerances regarding the dimensioning of the flow channel, as well as their relatively high cost.

[0017] Palmer et al. (2012) presents an alternative approach to providing a flow channel for a flow sensor. The flow sensor described therein comprises a wafer stack comprising a bottom substrate and a lid substrate, each of which is provided by a silicon wafer. The lid substrate is connected to the bottom substrate by fusion bonding. The flow sensor is advantageously suited for integration into other silicon-based devices. A membrane is present on the lid substrate, onto which three or five meander-like structures are applied to function as at least one heating element and as temperature sensors. The flow channel extends within the wafer stack along the bottom substrate and the lid substrate.As a result, a fluid can pass through an inlet area within the base substrate into a cavity in the cover substrate and through the outlet area on the base substrate into the flow channel. For flow measurement, an interfacer is provided, consisting of two interconnected circuit boards. A sensor structure is connected to the interfacer to perform the flow measurement.

[0018] EP 0689036 B1 describes a flow sensor that can be used with a manifold (pipe). The flow sensor comprises a semiconductor body in which a notch is introduced, which acts as a flow path for the flow sensor. The flow sensor also comprises a metal film that carries an insulating material on a top and bottom surface. The semiconductor body is mounted on a plate. Furthermore, the semiconductor body has a sealing ring arranged around the notch. The sealing ring can comprise a non-corrosive material such as nickel, copper, gold, or a solderable metal such as tin. When the flow sensor is used with a manifold, the flow sensor is connected to the manifold via the sealing ring.

[0019] US 6124632 discloses a monolithic silicon structure for controlling mass flow. The structure comprises a silicon chip positioned on a substrate. A channel extends within the silicon chip, through which a fluid can flow. Furthermore, an inlet region for the inlet and an outlet region for the outlet of the fluid are attached to the substrate. Furthermore, the structure has a valve control system comprising a valve structure and a base. A control circuit can be used to expose a section between the valve structure and the substrate by heating the valve control system, allowing fluid to flow between the inlet region and the outlet region.

[0020] EP 2040046 A2 relates to a flow sensor unit. The flow sensor unit comprises a flow sensor that is installed in a cavity of a metal body and is fixed or covered from above by a metal plate. The flow sensor comprises a sensor chip with a thermal sensor and a glass chip in which a flow channel is formed. The flow channel comprises an inlet opening for the entry of a fluid and an outlet opening for the exit of the fluid from the flow channel. The inlet and outlet openings of the flow channel in the glass chip correspond to the corresponding inlet and outlet openings for the fluid in the metal body, with an O-ring provided for sealing each.

[0021] EP 3457093 A1 discloses a gas measuring device for a combustible gas. The gas measuring device comprises a main housing defining a gas inlet and a gas outlet for the gas. Furthermore, a flow resistance element is present, which is positioned between the gas inlet and the gas outlet. Upstream of the flow resistance element, a first bypass opening is formed in a housing wall. Downstream of the flow resistance element, a second bypass opening is located in the housing wall. A sealing element, which is designed, for example, as an O-ring, can be present at the first and / or second bypass opening. A sensor module is attached in the area above these openings on the main housing. Preferred structures of the sensor module are described in more detail in EP 3457093 A1. The sensor module comprises, in particular, a bypass housing that defines a bypass channel.A thermal flow sensor is arranged within the bypass housing adjacent to the bypass channel. The flow sensor can be a microthermal flow sensor. The bypass housing is preferably made of a preformed plastic material using an injection molding process and can serve not only to form a bypass channel but also to protect the sensor components.

[0022] Although several approaches to providing packages for flow sensors are known in the prior art, there is a need for further optimization in this regard. For example, known approaches using preformed plastics are cost-intensive and can lead to undesirable tolerances, which complicate calibration and thus precise flow measurement. Providing a flow channel through the use of an interface has also proven complex, labor-intensive, and cost-sensitive. In particular, it has proven difficult to create a simple and reliable fluidic connection to the package of a flow sensor. Therefore, in light of the state of the art, there is a need for improved or alternative package designs for flow sensors.

[0023] Object of the invention

[0024] The object of the invention is to provide a sensor package that eliminates the disadvantages of the prior art. In particular, one object of the invention is to provide a sensor package comprising a sensor chip for measuring at least one flow parameter of a fluid, which is characterized by a compact design, enables a robust connection to various applications, and can be produced using a simple manufacturing process.

[0025] Summary of the invention

[0026] The object of the invention is achieved by the independent claims. Advantageous embodiments of the invention are described in the dependent claims.In a first aspect, the invention relates to a sensor package comprising a sensor chip for measuring at least one flow parameter of a fluid, a base plate and a cover, wherein the sensor package has openings on the cover and / or the base plate for providing an inlet region and an outlet region for the fluid, so that a flow channel is formed within the sensor package and wherein the sensor chip further has a thermal sensor comprising a heating element for providing a heat field and a sensor component for detecting a temperature response of the thermal sensor as a function of an influence of the fluid flowing in the flow channel on the heat field, characterized in that at least one opening on an outer side of the sensor package is laterally enclosed by a sealing material.

[0027] Advantageously, the sealing material easily enables a stable and fluid-tight connection between the sensor package and an application component, for example, a motherboard and / or a fluidic connector. In particular, the sealing material can be applied using simple and proven methods, so that a person skilled in the art does not require significant effort to integrate the sensor package according to the invention into the application context.

[0028] Another advantage is that the sealing material can fulfill multiple functions. For example, in addition to mechanical fixation and fluidic sealing, an electrical contact option can also be provided by selecting an electrically conductive material for the sealing material. Thus, the sealing material not only enables a simple, mechanically stable, and fluid-tight connection to a main flow channel whose fluid is to be measured, but can also simultaneously ensure an electrical connection of the electronic components contained in the sensor package, such as a thermal sensor and / or an electronic circuit, to an external circuit carrier, such as a motherboard.

[0029] Furthermore, the sealing material, especially if it contains an elastic material, can also provide additional cushioning. For example, this can be advantageous in cases of strong fluid flows, achieving damping.

[0030] In the field of MEMS microphones, it is known to attach a solder ring for a so-called bottom-port configuration for MEMS microphones to a circuit board. The solder ring can enclose an area attached to the sound inlet opening for MEMS microphones and is intended, in particular, to serve as an acoustic seal. According to the invention, it was recognized that a concept that is at least partially similar enables a simplified connection of flow sensors to the respective application.

[0031] This was by no means obvious, as flow sensors and MEMS microphones differ in their intended use and structural design, and the solder ring of MEMS microphones serves primarily as an acoustic seal. However, the application of a sealing material, which provides an opening on the side and outside of a sensor package for thermal flow measurement, represents a departure from known approaches and a significant simplification of packaging in the technological field of flow sensors. For the purposes of the invention, the sensor package preferably refers to a combination formed by the sensor chip, the cover, and the base plate.Therefore, in the context of the invention, the sensor package preferably comprises both a housing-like component, which is formed in particular by the base plate and the cover, as well as sensor components, such as those provided by the sensor chip and located within the housing-like component. The package as a housing is preferably formed by the base plate and the cover.

[0032] The sensor chip serves, in particular, to measure at least one flow parameter of a fluid. Accordingly, in the context of the invention, the sensor chip can also be referred to as a flow sensor. The fluid preferably refers to a medium that can flow, in particular, through the flow channel for which at least one flow parameter is to be measured by the sensor chip. The fluid itself preferably refers to a medium that can continuously deform under the influence of shear forces. In particular, the fluid can be present as a liquid or as a gas.

[0033] The at least one flow parameter refers to a quantity with which the fluid can be characterized in its physical and / or chemical properties. Preferably, the flow parameter can be selected from a group comprising a flow velocity, a pressure, a volume flow, a flow frequency (in the case of an oscillating flow of the fluid), a concentration, and / or a composition of the fluid, without being limited to these preferred parameters.

[0034] The sensor chip comprises a thermal sensor, which enables the detection of the flow through the flow channel. The thermal sensor preferably has a heating element, which serves to provide the thermal field, and a sensor component, which detects a temperature response. The sensor component, in particular, detects the influence of the fluid on the thermal field within the flow channel. The sensor chip preferably has a membrane, on which the thermal sensor is mounted. In particular, the sensor chip can preferably comprise a support structure, which has a cavity, on which the membrane extends and preferably on which the thermal sensor is positioned.

[0035] The sensor chip can be designed for different thermal measuring principles and / or preferably configured to be operated, preferably using an electronic circuit, in one or different modes in order to measure at least one flow parameter.

[0036] For example, the sensor chip can utilize an anemometric measuring principle, in which a heating element is preferably applied to or embedded in a membrane, and the fluid flow is measured based on heat transfer in or through the fluid, which changes with the flow velocity. Thus, it may be preferable for the heating element to be supplied with a constant power or maintained at a constant temperature. The flow of the fluid within the thermal field results in a temperature decrease through convection or heat transfer if a constant power was supplied, or it results in a necessary increase in the power supplied to the heating element if the temperature of the heating element is to be kept constant.Convection is proportional to the fluid flow rate, so the fluid flow velocity can be determined by the temperature decrease or by increasing the power to maintain the temperature. Preferably, the sensor component can be formed by the heating element itself, which can determine a flow-dependent temperature decrease, for example, based on a temperature-dependent resistance.

[0037] It may also be preferred for the sensor chip to be designed for a calorimetric measuring principle. A calorimetric measuring principle preferably utilizes the fact that the temperature profile around the heating element changes due to convection caused by the flow of the fluid. Preferably, one, preferably two, temperature sensors are positioned downstream and upstream of the heating element. Depending on the flow of the fluid, the temperature measured downstream and upstream of the heating element will differ. By measuring the temperature difference, it is possible to draw conclusions about a flow parameter of the fluid. The heating element can be heated with a constant voltage, a constant current, a constant power, or to a constant temperature.

[0038] Furthermore, it may be preferable to design the sensor chip for a so-called time-of-flight (TOF) measurement principle. This preferably measures the time between the moment a control signal is passed through the heating element and the time at which a maximum temperature rise is measured on a sensor component, for example, a temperature sensor, at a known distance from the heating element. The higher the flow rate, the shorter the so-called TOF.

[0039] By means of the sensor chip, in particular the temperature response of the thermal sensor, further properties of the fluid can preferably be determined, such as a thermal conductivity, a density, a pressure, a specific heat capacity, a thermal conductivity, a concentration and / or a composition of the fluid.

[0040] Those skilled in the art will know that, for example, a frequency-dependent temperature response can be used by means of an oscillating control to draw conclusions about the thermal conductivity and / or volumetric heat capacity of a fluid. For example, determining a phase between an oscillating control signal and a temperature response can be used, in particular, to determine thermal conductivity. The amplitude of a temperature response in the case of an oscillating control can depend, in particular, not only on the thermal conductivity but also on the volumetric heat capacity. Thus, the phase and amplitude of a temperature response compared to an oscillating control can be used, for example, to determine the thermal conductivity and / or volumetric heat capacity of the fluid.These thermal parameters can also be used to draw conclusions about, for example, the composition of the fluid and / or the concentration of a component within a mixed fluid. For example, if the thermal conductivity and / or volumetric heat capacity of various components of a mixed fluid, e.g., a mixed gas, is known, conclusions about the proportions of the individual components can be drawn by determining the thermal conductivity and / or volumetric heat capacity of the entire fluid.

[0041] The sensor chip is preferably mounted on the base plate. The base plate thus functions as a carrier for the sensor chip, which is incorporated within the sensor package. The cover is preferably connected to the base plate. The base plate and the cover preferably together form a casing or housing, which completely shields the sensor chip except for the intended inlet and outlet areas of the fluid. The package comprising the base plate and cover preferably fulfills a supporting function and a protective function. While the base plate, as the carrier of the sensor chip, fulfills a supporting function and provides a protective effect along an underside, a protective function along an upper side is achieved by the cover.

[0042] The structural elements of the sensor package are therefore formed, in particular, by a package and the sensor chip, wherein the package is preferably formed by a base plate and a cover. The package comprising the base plate and cover preferably acts as a housing for the sensor chip, in particular with regard to fulfilling a protective function for the sensor chip. It is therefore preferred that the sensor chip is mounted on the base plate and that the cover contacts the base plate in such a way that the sensor chip is protectively enclosed by the cover and the base plate.

[0043] Except for the at least one opening on the outside of the sensor package on the cover and / or base plate, the base plate and the cover form an enclosure around the sensor chip. Thus, a barrier (except for the at least one opening) is provided by the cover and base plate between the sensor chip and the environment, which provides protection against external influences and supports the reliable entry of a fluid into the sensor package and the outlet from the sensor package. At least one opening on the outside of the sensor package is laterally enclosed by the sealing material.

[0044] Applying the sealing material to an outer side of the sensor package preferably means that the sealing material is applied to a side of the base plate and / or cover facing away from the sensor chip. The outer side of the base plate and / or cover faces the environment, while an inner side of the base plate and / or cover forms a side facing the sensor chip.

[0045] In a preferred embodiment, the cover is a cap or a cover substrate. Accordingly, it is preferred that the cover is designed as a cap or a cover substrate and contacts the base plate for protective enclosure of the sensor chip. Using a cap or a cover substrate as a cover can ensure a firm and, at the same time, simple, inexpensive connection to the base plate. In particular, it is preferably not necessary to enclose the sensor chip in a package using a preformed plastic injection molding process, which is costly to manufacture and leads to higher tolerances. The inlet region represents a transition region through which the fluid flows from the environment of the package into the flow channel. Accordingly, the outlet region represents a transition section of the flow channel through which the fluid can leave the flow channel.Therefore, when measuring the at least one flow parameter by the sensor chip, it is preferred that the fluid flows into the flow channel starting from the inlet region and leaves the flow channel starting from the outlet region.

[0046] The thermal sensor comprises, in particular, a heating element and a sensor component. The heating element serves, in particular, to provide a thermal field. The thermal field refers to the heat that emanates from the heating element and can spread within the flow channel and be flowed through by the fluid. The terms thermal field and heat flow can be used synonymously in the context of the invention.

[0047] Preferably, the fluid influences the thermal field through its flow within the flow channel. This influence and the associated change in the thermal field can be detected by the sensor component of the thermal sensor. The change in the thermal field due to the fluid flow can also be referred to as modulation of the thermal field. The influence of the fluid on the thermal field, or the modulation, is reflected in particular in the temperature response, which is recorded by the sensor component of the thermal sensor. In other words, the sensor component serves to record a temperature response, which in turn depends on the modulation of the thermal field by the fluid.

[0048] The temperature response preferably refers to a measurement signal that is detected by the sensor component. The temperature response thus preferably represents a reaction of the thermal sensor, in particular of the sensor component, with respect to the properties or the flow of the fluid with regard to its effect on the thermal field. The sensor component can preferably be present as a temperature sensor, so that the temperature response is preferably detected by the temperature sensor. It can also be preferred for the sensor component to be provided by the heating element itself, so that the temperature response preferably represents a measurement signal of the heating element that is influenced by the flow of the fluid. The temperature response can preferably relate to a thermal variable that can be read out in particular by the sensor component, such as the temperature itself.The temperature response may preferably also mean an electrical signal, which can preferably be described by an electrical voltage and / or an electrical current.

[0049] A flow channel is incorporated within the sensor package. The flow channel specifically defines a path through which the fluid to be measured can flow. Furthermore, the flow channel brings the fluid sufficiently close to the thermal sensor, allowing the fluid to influence the thermal field provided by the heating element. In other words, the flow channel provides a path for the fluid flow through which the fluid can spread to be measured by the thermal sensor. The flow path, which is used to influence the thermal field of the heating element, can be defined by the flow channel. The flow channel specifically includes the inlet region, the outlet region, and an intermediate spatial region.

[0050] For example, it can be exploited that heat transport through the sensor component can be detected as a result of the fluid flow, whereby the heat transport changes with the flow velocity. For example, it may be preferable for the heating element to be supplied with a constant power or to be kept at a constant temperature. The flow of the fluid within the heat field results in a decrease in temperature through convection or heat transport if a constant power was supplied, or it results in a necessary increase in the power supplied to the heating element if the temperature of the heating element is to be kept constant. Convection is proportional to the flow rate of the fluid, so that the flow velocity of the fluid can be determined, for example, by the decrease in temperature or by the increase in power to maintain the temperature.

[0051] The inlet region and the outlet region are formed by openings in the sensor package. An opening preferably refers to a recess in the sensor package, for example in the base plate and / or cover, through which the fluid can enter and / or exit. In preferred embodiments, the openings for providing the inlet region and the outlet region are located on the base plate. In preferred embodiments, the openings for providing the inlet region and the outlet region are located in the cover. It may also be preferred for the openings for providing the inlet region or the outlet region to be located on the base plate or cover.

[0052] At least one of the openings is laterally enclosed by the sealing material on the outside of the sensor package. Preferably, those openings on the outside of the sensor package are laterally enclosed by a sealing material, which are intended to enable a connection to an application, for example, a mainboard and / or a fluidic connection. The outside of the sensor package preferably refers to the side of the sensor package facing away from the interior of the sensor package and in which the sensor chip is inserted.

[0053] The fact that the sealing material laterally encloses the at least one opening preferably means that the sealing material has a self-contained configuration along the at least one opening. This can mean, for example, that the sealing material has an elliptical, preferably annular, structure on the outside laterally around the at least one opening. Other self-contained shapes can also be preferred, for example, triangular, square, pentagonal, hexagonal, or other polygonal contours.

[0054] The lateral enclosing is preferably intended to express that the sealing material applied to the outside of the sensor package completely encloses the at least one opening without covering the opening. The sealing material preferably borders the at least one opening on the outside of the sensor package. The sealing material therefore extends along the outside without getting into the opening itself, so that turbulence in the transition regions is reduced or avoided. The laterally enclosing sealing material is preferably essentially flat. A flat design preferably means that the sealing material has a circumference which is many times greater than a thickness or height of the sealing material, for example by a factor of 1, 5, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more. A thickness or height of the sealing material preferably means the protrusion orExpansion of the sealing material measured from an outer side of the sensor package, e.g., a base plate and / or cover, outward. A length or circumference preferably refers to the expansion along the closed shape of the sealing material, while a width is orthogonal to the height or thickness of the sealing material.

[0055] In the case of a ring shape, the width refers, for example, to a difference between an inner and outer radius. The sealing material can preferably have a thickness of 0.1 - 10 mm (millimeters), preferably 0.5 - 5 mm, and / or a width of 0.1 - 3 mm, preferably 0.2 - 2. The aforementioned preferred ranges for a thickness and / or a width have proven advantageous in ensuring a reliable fluidic connection. Preferably, the circumference of the sealing material essentially corresponds to the circumference of the inlet region and the outlet region, since the sealing material laterally encloses these regions. Thus, the dimensioning of the circumference of the sealing material is preferably dependent on the circumference of the inlet region and the outlet region.

[0056] In a further preferred embodiment, the sensor package is characterized in that the sealing material laterally encloses the at least one opening in an annular manner and forms a sealing ring.

[0057] An annular configuration of the sealing material preferably means a substantially circular configuration of the sealing material. A length preferably refers to the extent of the sealing material along a (central) circumference of the sealing ring or circle. A width of the sealing ring can preferably be formed by the difference between two concentric circles, i.e., an inner circle (along the inner circumference of the sealing ring) and an outer inner circle (along the inner circumference of the sealing ring). An annular configuration of the sealing material can also be referred to as a sealing ring in the context of the invention.

[0058] Advantageously, a sealing ring is particularly easy to install and is particularly suitable for circular openings that form an inlet and / or outlet area. Therefore, a sealing ring preferably ensures that it laterally encloses a circular opening, i.e., borders it on the outside, making it ideal for reliable fastening.

[0059] In a further preferred embodiment, the sensor package is characterized in that the sealing material comprises a solder material, a bonding material, an adhesive and / or a plastic, preferably an elastomer.

[0060] A bonding material preferably refers to a material that is used in bonding. Bonding. Bonding preferably describes a process step in semiconductor and / or microsystem technology in which a substrate can be connected to another substrate and / or another component. For this purpose, it is preferable to use the appropriate bonding material that is required for the respective bonding process in order to be able to provide the connection. The bonding material can, for example, be applied to the sensor package or to another application, such as a mainboard. The bonding process is then carried out to form a bond connection between the sensor package and the other application. Various methods can preferably be used for bonding. These are also referred to as bonding processes or bonding methods.Preferred bonding processes include direct bonding, anodic bonding, interlayer bonding, glass frit bonding, adhesive bonding, and / or selective bonding, which require the appropriate bonding materials.

[0061] An adhesive preferably refers to a substance that enables bonding. Advantageously, a laterally enclosed form of the adhesive can be provided at the opening without the need to apply heat and / or pressure. Instead, the adhesive solidifies after a certain time interval, leaving the adhesive as a self-contained form on the outside around the at least one opening. When using an adhesive, the application of mechanical pressure is advantageously sufficient to enable connection of the sensor package to another application, such as the base plate. In particular, it is not necessarily necessary to specify an external supply of heat and / or pressure.

[0062] It may also be preferable to provide the sealing material using a plastic. The plastic can preferably be present as an elastomer. An elastomer refers to a dimensionally stable plastic which is additionally deformable, in particular having a glass transition point which is below room temperature. Preferably, a sealing ring can be used which comprises a plastic, in particular an elastomer which, for example, comprises rubber, i.e. a sealing ring in the sense of a sealing ring for hydraulic applications. The sealing ring is preferably applied to a border of the inlet region and / or outlet region on the outside of the sensor package. In this case, a mechanical connection between the sensor package and an external application, in particular the base plate, is advantageously achieved by a pressure effect of the sealing ring.Even high mechanical pressure from the outside does not necessarily have to be applied to achieve a strong connection.

[0063] In a further preferred embodiment, the sensor package is characterized in that an electrical connection is present through the sealing material, which can be used for an electrical connection.

[0064] Advantageously, in addition to a stable mechanical connection, a robust and electrical connection is also achieved through the use of the sealing material. The provision of an electrical connection by the sealing material is particularly present when the sealing material comprises an electrically conductive material. This is preferably the case when a soldering material or as a sealing material for forming a solder ring is used. Usability for an electrical connection is preferably given if the electrically conductive sealing material enables an electrical connection from the outside to components within the sensor package. For this purpose, the electrically conductive sealing material therefore preferably has an electrical or galvanic connection to internal components of the sensor package (e.g., components of the thermal sensor).If an electrically conductive sealing material encloses, for example, an opening in a base plate, it is preferred that electrical lines lead through the base plate from the outer sealing material to an inner side, for example in the form of through-holes.

[0065] The electrically conductive sealing material thus advantageously not only enables a fluid-tight connection to an application component, e.g., a motherboard, but can also serve as an electrical connection.

[0066] This was not previously provided for in the prior art. For example, EP 0689036 B1 describes a flow sensor with a sealing ring, which can comprise a non-corrosive material such as nickel, copper, gold, or a solderable metal such as tin. However, the sealing ring is not attached externally, but rather positioned as an intermediate component between the flow sensor and a distributor. Furthermore, it cannot serve to provide an electrical connection.

[0067] Thus, the sealing material can advantageously provide a mechanical connection, a fluidic seal and additionally an electrical connection.

[0068] In a further preferred embodiment, the sensor package is characterized in that the sealing material comprises a solder material which is present as a solder ring, wherein the solder material preferably comprises a material selected from a group comprising tin, zinc, copper, silver, gold, their compounds and / or alloys.

[0069] A solder material preferably refers to a material that is used in particular for soldering. By melting the solder material, it can be structured in such a way that it can laterally enclose an opening on the outside of the sensor package, i.e. has a self-contained shape. For structuring the solder material, a temperature is preferably applied that is essentially the same as or higher than the melting temperature. By applying an appropriate melting temperature, the solder material on the outside of the sensor package can adapt to the inlet and outlet areas so that the solder material can form a closed ring (solder ring). Shortly after the solder ring has formed, the solder material can be used in the molten state to create a strong and robust connection to an external application, e.g. a motherboard.

[0070] A solder ring preferably refers to a ring-shaped solder material that is applied to the outside of the sensor package to enclose at least one opening. The use of a solder ring for the sealing material has proven particularly advantageous. In addition to a secure and long-lasting, fixed connection on the outside, the solder ring can also be used to fulfill electrical functions, for example, for supplying power and / or transmitting (measurement) signals. For this purpose, the solder ring preferably has an electrical connection to components of the thermal sensor, for example, a heating element, for its power supply, or a sensor component for reading measurement data.Furthermore, it is advantageous that the design of the solder ring is simple, so that a considerable process efficiency is achieved with regard to the application of the sealing material, which is intended to enclose at least one opening laterally on the outside.

[0071] The aforementioned preferred materials for forming the solder ring are particularly advantageous in that they preferably have a melting temperature that is lower than a critical temperature for the sensor package or for temperature-sensitive components of the sensor package, thus enabling reliable attachment of the solder ring. Furthermore, the listed materials for providing the solder ring are inexpensive to acquire and can be easily implemented during soldering, particularly in the sensor package according to the invention, to enclose the at least one opening laterally on the outside.

[0072] In a further preferred embodiment, the sensor package is characterized in that the base plate is present as a semiconductor substrate or as a circuit carrier, preferably as a printed circuit board.

[0073] A semiconductor substrate preferably refers to a round or square disc with a thickness in the millimeter or submillimeter range. Semiconductor substrates can also be synonymously referred to as a wafer. The semiconductor substrate preferably refers to a component to be processed and / or a component used for the placement of the sensor chip. Semiconductor substrates are typically manufactured from monocrystalline or polycrystalline (semiconductor) blanks, so-called ingots.

[0074] Semiconductor substrates are particularly easy and cost-effective to process in semiconductor and / or microsystem technology and are also well-suited for mass production. These materials are also particularly suitable for doping and / or coating to achieve the desired mechanical, electrical, thermal, and / or optical properties in specific areas.

[0075] A circuit carrier preferably refers to a component comprising an electrically insulating material on which electrically conductive connections (conductor tracks) and / or electronic components or assemblies are located. A circuit carrier therefore preferably refers to a carrier for electronic components or electrically conductive connections that serves both for mechanical fastening and electrical connection.

[0076] On or in the circuit carrier, there are preferably electronic components and electrical connections which enable an electronic connection, for example, through wire bonds, conductor tracks and / or conductor strips. The circuit carrier therefore functions both as a mechanical carrier and for an electrical connection for implementing electrical functions. The electrical connections of the circuit carrier are used, in particular, for the electrical contacting of components. The insulating material of the circuit carrier preferably specifies a basic shape of the circuit carrier, in particular to specify a mechanical contact with the sensor chip. The sealing material can, in particular, specify a mechanical connection with the circuit carrier. Furthermore, the sealing material, in particular if it comprises an electrically conductive material (e.g.as a solder ring) to enable an electrical connection between the circuit carrier and the sensor chip.

[0077] It may also be preferred that an electronic circuit is incorporated on the circuit carrier, which can send, receive and / or process electrical signals for measuring the at least one flow parameter.

[0078] A printed circuit board is preferably used as the circuit carrier. A printed circuit board preferably refers to a specific type of circuit carrier that includes electrical connections and provides mechanical support for surface-mounted and / or socketed components. A printed circuit board preferably comprises fiberglass, an epoxy, and / or another composite material as the insulating material.

[0079] A printed circuit board is advantageous in that it is particularly easy to provide two openings that correspond to the inlet and outlet areas of the flow channel on the sensor chip. Furthermore, printed circuit boards are characterized by their high stability, allowing even flows with high hydrodynamic pressure to be measured accurately and reliably using the flow sensor array, without the risk of possible mechanical deformation caused by the fluid and thus distorting the measurement results. Furthermore, printed circuit boards are readily available, allowing them to be used cost-effectively as a base plate for the sensor chip.

[0080] Another particular advantage is that, when a solder ring is attached to the circuit board, the sensor package can be provided as an SMD component. An SMD component (surface mounted device) is a component that enables direct connection to another or external application, for example, by directly connecting the sensor package to a motherboard using surface mounting technology. This eliminates the need to implement wire connections, etc., allowing considerable space savings in terms of positioning the sensor package. Furthermore, it is a major advantage that the solder ring achieves favorable electromagnetic compatibility (EMC) and prevents interference in signal transmission.Preferably, the solder ring and / or the cover, if the latter comprises an electrically conductive material, can be connected in such a way that one or both of the components are grounded or are connected to GND.

[0081] In a further preferred embodiment, the sensor package is characterized in that the cover is present as a cap or as a cover substrate.

[0082] The cover preferably means a solid and in particular protective enclosure for the sensor chip. For this purpose, the sensor chip is preferably attached to the base plate and the cover is connected to the base plate. By selecting the dimensions of the cover, it is possible in particular to select the design of the flow channel through which the fluid flows within the sensor package, i.e. in particular between the base plate and the cover. By applying the cover to the base plate, a hermetic enclosure of the sensor chip within the sensor package is advantageously enabled. Hermetic enclosure preferably means encapsulation of this type, whereby apart from the inlet and outlet regions, no fluidic mass exchange can take place with the sensor package. Thus, the cover in particular fulfills a protective function for the sensor chip.

[0083] In preferred embodiments, the cover can be designed to be substantially flat, so that the height of the cover is preferably substantially predetermined by the height of the sensor chip. In further preferred embodiments, the covers can have depressions and / or elevations, for example in the form of hollow spaces, cavities, corrugations and / or grooves. Furthermore, it can be preferred that the flow channel, in particular a course of the flow channel, is at least partially determined by the cover. For example, the flow channel can run at least partially between the sensor chip and the cover. It can also be preferred that the flow channel runs through the sensor chip. Furthermore, it can be preferred that the flow channel runs at least partially, preferably completely, within a cavity of the sensor chip.

[0084] In a further preferred embodiment, the sensor package is characterized in that the sensor chip is mounted on the base plate and the cover is connected to the base plate in such a way that the cover covers the sensor chip at least partially, preferably completely.

[0085] The design of the flow channel can be selected through the area between the base plate and the cover. In particular, the base plate and the covers represent boundaries for the fluid flowing through the flow channel within the sensor package. The sensor chip is preferably positioned on the base plate. The base plate can therefore be regarded as a lower boundary. Against this background, the cover can accordingly be regarded as an upper boundary. For this purpose, in particular the cover and the base plate are connected to one another. This results in at least partial coverage, preferably complete coverage, of the sensor chip by the cover. In particular, there is a fixed connection between the sensor chip and the base plate in order to be able to carry out a reliable measurement of the at least one flow parameter.

[0086] Preferably, the cover may be formed by a cap or a lid substrate.

[0087] A cap preferably refers to a curved cover with an upper cover and side walls that enclose a cavity in which the sensor chip can be arranged. The cap can preferably be connected to the base plate via the side walls, whereby the connection of the side walls to the base plate can be referred to as a sealing edge. The cap thus preferably seals a sensor chip on the base plate from above.

[0088] The cover substrate preferably refers to a substrate with which the sensor chip can also be covered or enclosed. The lid substrate can be a conventional wafer or an SOI substrate. It may be preferred that the lid substrate has a cavity, so that a side region of the lid substrate is connected to the base plate and the cavity is mounted above the sensor chip.

[0089] In a preferred embodiment, the cover comprises a dielectric, wherein the dielectric is preferably selected from a group comprising silicon nitride, silicon dioxide, aluminum oxide, aluminum nitride, polyimide and / or a polymeric material.

[0090] In a further preferred embodiment, the cover comprises a semiconductor, wherein the semiconductor is preferably selected from a group comprising monosilicon, polysilicon, germanium and / or chalcogenide.

[0091] In a further preferred embodiment, the cover comprises a conductor, wherein the conductor is preferably selected from a group comprising aluminum, titanium, zinc and / or a noble metal, preferably selected from a group comprising gold, platinum, iridium, palladium, osmium, silver, rhodium and / or ruthenium.

[0092] It may also be preferred for the cover to comprise one or more combinations of materials formed by a dielectric, a semiconductor, and / or a conductor. For example, the cover may comprise a metallically coated thermoplastic that has been provided by an injection molding and subsequently coated.

[0093] In a further preferred embodiment, the sensor package is characterized in that the sensor chip is connected to the base plate directly or via a connecting means, wherein the connecting means preferably comprises an adhesive, a solder material and / or a bonding material.

[0094] A direct connection between the sensor chip and the base plate preferably means a direct connection, i.e., a connection without an intermediate component (as a connecting means), but rather with the sensor chip mounted directly on the base plate. A direct connection can be achieved, for example, by a press connection. Some bonded connections can also be used for a direct connection, for example, after applying thermocompression bonding.

[0095] A connection via a connecting means preferably means that the connecting means that enables a long-lasting connection between the base plate and the sensor chip is present between the base plate and the sensor chip. The aforementioned preferred connecting means, comprising an adhesive, a solder material, and / or a bonding material, have proven advantageous for a particularly stable and fluid-tight connection. Any vibrations and / or shocks of the sensor chip during the fluid flow around it through the flow channel can be advantageously avoided, thus enabling a precise measurement of at least one flow parameter of the fluid.

[0096] The average person skilled in the art is able to select a preferred connection type between the sensor chip and the base component depending on the specific design, dimensions, and / or material selection. In a further preferred embodiment, the sensor package is characterized in that the heating element is an electrical heating element, preferably a heating resistor.

[0097] The heating element preferably refers to the component of the thermal sensor from which the heat field or heat flow emanates by releasing heat energy. An electric heating element preferably refers to a heating element capable of converting electrical energy into heat energy, which in the context of the invention is used as a heat field and transferred to the sensor component, preferably the temperature sensor. In an electric heating element, the heat energy or heat field is preferably generated by using an electrically conductive material through which an electric current flows and is heated by Joule heating. A heating resistor has proven particularly suitable for this purpose. This preferably comprises metallic alloys that do not melt and / or oxidize even at particularly high temperatures.

[0098] In a further preferred embodiment, the sensor chip is characterized in that the sensor component is formed by a temperature sensor, wherein the temperature sensor is preferably selected from a group comprising a thermocouple, a diode, a thermistor and / or a thermopile.

[0099] A temperature sensor, as a preferred sensor component, is capable of determining the influence of the fluid on the thermal field through temperature measurement. The aforementioned preferred options, including a thermocouple, a diode, a thermistor, and / or a thermopile, have proven particularly useful for reliable temperature measurement.

[0100] A thermistor preferably means a component comprising an electrical resistance whose value changes reproducibly with temperature. Thermistors are divided into thermistors and cold thermistors based on their temperature behavior. A thermistor has a negative temperature coefficient and is able to conduct electrical current better when hot than when cold. A cold thermistor has a positive temperature coefficient and is able to conduct electrical current better when cold than when hot. In the context of the invention, a thermistor or a cold thermistor can preferably be used as a thermistor. By means of a thermistor, conclusions about a modulation of the thermal field and thus at least one flow parameter of the fluid can be determined in a simple and precise manner based on a changing electrical resistance.

[0101] A thermocouple preferably refers to an arrangement comprising a pair of electrically conductive materials that are connected to one another at one end and, due to the thermoelectric effect, allow a conclusion to be drawn about the measured temperature. Electrical energy is provided when there is a temperature difference along the arrangement. A thermopile refers to an element that has several thermocouples. The thermocouples of the thermopile are preferably connected electrically in series and thermally in parallel. The measuring point of the thermocouple or thermopile is referred to as the hot junction, hot end, or by the English terms hot end or hot junction, and forms one end of a thermocouple. The other end, which is analogously referred to as the cold junction, cold end, or by the English terms cold end or cold junction, refers to a reference point for determining a temperature difference.Preferably, an electronic circuit and / or a computing unit for processing the temperature measurement is connected to the cold junction.

[0102] A diode can also function as a temperature sensor and thus as a preferred sensor component. This can be exploited, for example, by the fact that the forward voltage of a diode changes essentially linearly with temperature. The higher the temperature, the lower the forward voltage, and vice versa. Accordingly, the change in the forward voltage can be used to draw conclusions about a change in temperature.

[0103] In a further preferred embodiment, the heating element itself functions as a sensor component, i.e., a sensor component can preferably be provided by the heating element without a temperature sensor being used as a sensor component. The effect of the heating element as a sensor component can, for example, be enabled in the same way as the 3-omega method known from the prior art. In the 3-omega method, a thermal property, such as thermal conductivity, is determined. A heating element itself is used as a temperature sensor and is fed with an oscillating control signal. Due to the fed-in power, the temperature of the heating element changes at the same frequency as the control signal. The amplitude and the phase shift compared to the fed-in power depend on the thermal conductivity and the frequency.The temperature oscillations lead to resistance oscillations in the heating element, which can be described, among other things, by a resistance amplitude, which in turn depends on a temperature coefficient of the electrical resistance of the heating element. From this, the voltage across the heating element can be calculated by applying Ohm's law. This voltage contains a component with three times the frequency (3 μJ) and a corresponding amplitude proportional to the temperature amplitude of the heating element.

[0104] In a further preferred embodiment, the sensor package is characterized in that the sensor chip has a membrane on which the thermal sensor is positioned, wherein the membrane preferably comprises an electrically conductive material and / or a dielectric material, wherein the electrically conductive material is preferably selected from a group comprising semiconductors and / or metals, in particular silicon, polysilicon, graphene, chalcogenide, wherein the dielectric material is preferably selected from a group comprising silicon nitride, silicon dioxide, aluminum oxide, aluminum nitride, polyimide and / or a polymeric material.

[0105] The membrane denotes a preferred component of the sensor chip, which has a flat design. The flat design of the membrane preferably means that dimensions such as a length and / or width are many times greater than an orthogonal height or thickness of the membrane. Thus, the length and / or width can be greater than the thickness by a factor of 1.5, 2.5, 10, 100, 1,000, 10,000, or more. The thickness of the membrane is preferably between approximately 0.1 and 20 μm, preferably between approximately 0.2 and 10 μm, particularly preferably between approximately 0.5 and 5 μm, most preferably between approximately 0.5 and 2 μm.

[0106] The membrane serves, in particular, to position the thermal sensor. The preferred membrane is preferably intended to provide thermal insulation of the heat field provided by the heating element and to serve as a support for the thermal sensor. Furthermore, it may also be preferable to use the membrane to ensure reliable media separation by at least partially covering a flow channel running underneath.

[0107] The preferred materials for the membrane have proven advantageous in that, in addition to their excellent design options as a membrane, they also offer reliable thermal insulation, thus reducing or eliminating heat conduction through the membrane. This further improves the accuracy of the measurement results, so that the influence of the fluid on the thermal field essentially remains relevant. Furthermore, the preferred materials have proven particularly advantageous with regard to processing for providing the membrane and sufficient mechanical stability. In particular, the membrane is also preferably designed to avoid any vibrations caused by the flow of the fluid in order to reduce distortions of the measurement result.

[0108] The region of the membrane on which the thermal sensor is positioned preferably comprises a dielectric material. The membrane can also preferably comprise an electrically conductive material, so that electrical contact with the thermal sensor can be established.

[0109] In a further preferred embodiment, the sensor package is characterized in that the sensor chip has a cavity above which a membrane extends, on which the thermal sensor is positioned.

[0110] The sensor chip preferably comprises a support structure to which the cavity is attached. The support structure preferably comprises a lateral boundary, in particular in the form of side walls, along which the membrane extends above the cavity. Thermal insulation is advantageously achieved by the cavity. In particular, the introduction of the cavity on the sensor chip ensures that the thermal field provided by a heating element is predominantly, preferably substantially exclusively, influenced by the fluid, and that distortion of measurement results due to heat conduction through the sensor chip itself, in particular through the preferred support structure, is reduced.

[0111] In a further preferred embodiment, the sensor package is characterized in that the sensor chip has an aperture, which is preferably attached to the membrane, wherein the aperture is present as a section of the flow channel or the flow channel runs at least partially within the cavity. It may also be preferred for the flow channel to run substantially entirely beneath the cavity of the sensor chip. In a further preferred embodiment, the sensor package is characterized in that the flow channel runs within the sensor package, and the inlet and outlet regions of the flow channel are present through openings in the base plate and / or the cover.

[0112] The flow channel, in particular, defines a path through which the fluid can flow within the sensor package. The design of the flow channel can also ensure, in particular, sufficient proximity of the flowing fluid to the thermal sensor, so that measurement of flow parameters of the fluid based on a modulation or influence of the thermal field provided by the heating element is possible. In other words, the flow channel provides a path for the flow of the fluid through which the fluid can spread in order to be measured by the thermal sensor. The influence of the fluid flowing through the flow channel on the thermal field is determined, in particular, based on the temperature response. The at least one flow parameter of the fluid can be measured using the temperature response.

[0113] To enable flow into the flow channel through the sensor package, openings are introduced into the sensor package, which serve as inlet and / or outlet areas. Thus, the opening allows the fluid to enter the sensor package and exit it. A variety of options are advantageously available for the introduction of openings into the sensor package.

[0114] In a preferred embodiment, the sensor package is characterized in that the inlet region is present as an opening in the cover and the outlet region is present as an opening in the cover.

[0115] Thus, the fluid can enter the sensor package through the opening, which serves as the inlet area, and exit the sensor package through the cover, which serves as the outlet area. The preferred embodiment, in which the openings for an inlet area and an outlet area are incorporated into the cover, is particularly well suited for connecting the sensor package to a main board and / or a fluidic connection via the cover (see Fig. 4).

[0116] In a further preferred embodiment, the sensor package is characterized in that the inlet region is present as an opening in the base plate and the outlet region as an opening in the cover or the inlet region is present as an opening in the cover and the outlet region as an opening in the base plate.

[0117] In the first embodiment, the fluid enters the sensor package via the opening in the base plate, which acts as the inlet area. The fluid spreads within the flow channel and reaches sufficient proximity to the thermal sensor to influence the thermal field provided by the heating element. The temperature response recorded by the sensor component can be used, as described, to determine at least one flow parameter of the fluid. The fluid can exit the sensor package via the opening in the cover, which acts as the outlet area (see also Fig. 3).

[0118] In the second embodiment, the fluid enters the sensor package in the opposite direction via an opening in the cover, which acts as an inlet area, and flows out again through an opening in the base plate. In this case, too, the flow channel runs through the space formed by the base plate and cover.

[0119] In this respect, the length of the flow path can be influenced by a geometric design of the cover, for example a dimensioning of a cap and / or cover substrate.

[0120] In a further preferred embodiment, the sensor package is characterized in that at least one opening for forming the inlet region and / or the outlet region is present on the base plate and / or the cover, and an aperture is present within the sensor chip, so that the flow channel runs at least partially through the aperture on the sensor chip. The aperture in the sensor chip can be formed, for example, by an opening within a membrane on which the thermal sensor is positioned (see also Fig. 5). The thermal sensor can preferably comprise a heating element and a sensor component, for example a temperature sensor, which are mounted in sufficient proximity to the aperture. This allows a particularly strong influence of the fluid on the thermal field provided by the heating element to be utilized to carry out a sensitive measurement.

[0121] In a further preferred embodiment, the sensor package is characterized in that the inlet region is present as an opening in the base plate and the outlet region is present as an opening in the base plate.

[0122] The fluid enters the sensor package via the inlet area, which is provided as an opening in the base plate. After the fluid enters the sensor package, it is possible for the fluid to influence the thermal field provided by the heating element. The fluid can leave the sensor package via the opening in the base plate, which acts as the outlet area. It may be preferred that the openings are introduced into the base plate in such a way that the flow channel runs partially within the preferred cavity, which the sensor chip encompasses and above which the thermal sensor is located. The cavity preferably means a cavity beneath a membrane, on which the thermal sensor is preferably attached to detect a temperature response.

[0123] In a further preferred embodiment, the sensor package is characterized in that the sensor chip has a substrate, wherein the thermal sensor is positioned on a front side of the substrate and at least one section of the flow channel is formed below the thermal sensor within the substrate, which section was formed starting from a back side of the substrate by removing the substrate in regions, wherein the substrate is preferably designed monolithically.

[0124] The substrate preferably comprises a corresponding inlet region and a corresponding outlet region. This preferably means that the substrate comprises a corresponding inlet region into the section of the flow channel within the sensor chip, which is fluidically connected to the inlet region on the sensor package. Preferably, the corresponding outlet region on the substrate is fluidically connected to the outlet region on the sensor package. Thus, the fluid enters the sensor package via the inlet region and flows through the section of the flow channel within the substrate of the sensor chip, entering it via the corresponding inlet region. The fluid can leave the package again via the corresponding outlet region of the substrate and the outlet region on the sensor package (see also Figs. 7 and 8).

[0125] The substrate can, in particular, serve to form the preferred support structure for the sensor chip, on which the thermal sensor is mounted. Accordingly, it is preferred that the thermal sensor be mounted on a front side of the substrate to enable measurement of the fluid.

[0126] The substrate may comprise, for example, a glass, a ceramic and / or a semiconductor material, for example monosilicon, polysilicon, silicon carbide, silicon germanium, germanium, gallium arsenide and / or gallium nitride.

[0127] In particular, it is preferred that the substrate is monolithic. In the context of the invention, monolithic means, in particular, a one-piece substrate. It is therefore preferred that the substrate is present as a single substrate and is no longer obtained in pieces by connecting (e.g. bonding) two or more substrates. An unprocessed substrate, i.e. a substrate in which no flow channel has yet been introduced, can accordingly preferably be provided as a monolithic block, i.e. as a block which essentially consists of the substrate material. The monolithic design of the substrate in particular avoids a stack-like structure for the thermal sensor, i.e. multiple substrates are not stacked on top of one another and / or connected to one another.

[0128] Instead, in the preferred embodiment, the flow channel is preferably incorporated into a single monolithic substrate. The front side preferably refers to an upper side of the substrate on which the thermal sensor is mounted, preferably on a membrane held by the substrate, as explained above. The back side of the substrate refers to a surface opposite the front side, ie, preferably opposite an (upper) side of the substrate on which the thermal sensor is positioned.

[0129] The region-by-region removal of the substrate, starting from the rear side, can be carried out in such a way that the flow channel corresponds essentially, or preferably exactly, to the height of the substrate in terms of its height. It can also be preferred for the region-by-region removal of the substrate to be carried out in such a way that a residual thickness remains on the substrate. The region-by-region removal of the substrate to provide the flow channel means, in particular, the removal of sections of the substrate (e.g., using known etching processes for semiconductor materials) in order to configure the flow channel. In particular, as a result of or after the region-by-region removal of the substrate, a free volume exists within the substrate, which forms a section of the flow channel within the sensor chip.The section of the flow channel can thus preferably be bounded laterally by the substrate, while the section of the flow channel is bounded upwards by a membrane held by the substrate. However, the section of the flow channel can also be bounded upwards by the substrate itself, provided that a residual upper thickness preferably remains when the substrate is removed from the rear.

[0130] At the bottom, however, the section of the flow channel is preferably limited by the base plate, the openings of which, as explained, correspond to an inlet or outlet area for an inlet or outlet of the fluid into the section of the flow channel within the substrate of the sensor chip.

[0131] Advantageously, the structuring of the flow channel section can be performed in a single process sequence by removing the flow channel section in regions starting from the rear side. It may also be preferred to perform multiple process steps to create the flow channel section. The inlet region represents a transition region through which the fluid enters the flow channel section within the substrate. Accordingly, the outlet region represents a transition region of the flow channel through which the fluid can exit the flow channel section within the substrate.

[0132] This can advantageously be done under significantly controlled conditions so that, for example, turbulence is avoided and the quality and sensitivity of the measurement of at least one flow parameter is improved.

[0133] Furthermore, the fluidic properties of the flow channel section within the monolithic substrate can advantageously be adjusted with particular precision and consistency. For example, the width of the flow channel section can be adjusted extremely precisely using known etching processes for the partial removal of the substrate. Error tolerances that could inherently arise when forming flow channels in assembled stacks due to the connection technology are avoided. By forming the flow channel section within the monolithic substrate, it can also be ensured that the dimensions of the flow channel section remain constant and, in particular, are not influenced by the flow behavior of the fluid itself.

[0134] In a further aspect, the invention relates to a sensor package arrangement comprising a. a sensor package according to one of the preceding claims as described above, and b. a main board, characterized in that the sensor package is installed on the main board.

[0135] The sensor package assembly comprises, in particular, the sensor package described above and a mainboard. The mainboard refers to a central circuit board on which electronic components are mounted to ensure the functionality of the sensor package, particularly with regard to controlling the heating element and / or evaluating the temperature response. In particular, components such as a socket for an electronic circuit, the electronic circuit itself, slots, BIOS chips, interface modules, and / or slots for expansion cards can be mounted on the mainboard.

[0136] The sensor package is preferably installed on the mainboard. This can preferably mean that a mechanical and / or electronic connection is established between the sensor package and the mainboard. In particular, this connection is sufficiently stable, which applies to both a mechanical and an electronic connection.

[0137] This advantageously ensures that the flow of the fluid through the flow channel of the sensor package avoids any disadvantage to one type of connection.

[0138] A particular advantage is that when a solder ring is attached to the circuit board, the sensor package can be implemented as an SMD component, enabling direct connection of the sensor package to a circuit board using surface mounting. Advantageously, it is not necessary to implement wire connections, etc. This can result in significant space savings with regard to the positioning of the sensor package. Furthermore, it is a great advantage that the solder ring achieves advantageous electromagnetic compatibility (EMC) and prevents interference in signal transmission. Preferably, the solder ring and / or the cover, if the latter comprises an electrically conductive material, can be wired in such a way that one or both of the components are grounded or connected to GND.

[0139] In a further preferred embodiment, the sensor package arrangement is characterized in that the main board has main board openings and the openings are connected to the main board openings via the sealing material to provide an inlet region and an outlet region of the sensor package.

[0140] In other words, the sealing material on the sensor package can enable a connection between the main board and the sensor package assembly. In particular, direct attachment of the main board openings to the inlet and outlet regions of the sensor package can be enabled. This allows the fluid to enter the sensor package assembly by flowing through the inlet region via a main board opening and exiting the sensor package assembly via the flow channel through the outlet region and another main board opening. Furthermore, the sealing material can advantageously enable a precise connection between the inlet and outlet regions and the main board openings.

[0141] In a further preferred embodiment, the sensor package arrangement is characterized in that the sensor package arrangement comprises an electronic circuit configured to determine the at least one flow parameter based on a measurement by the sensor component, wherein the electronic circuit is preferably mounted on the main board.

[0142] For the purposes of the invention, an electronic circuit preferably refers to a combination of individual electrical or electromechanical elements in a functional arrangement. The electronic circuit preferably allows data or electrical signals to be sent, received, and / or processed.

[0143] Preferred electronic circuits include, without limitation, an integrated circuit (IC), application-specific integrated circuits (ASIC), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, a microcomputer, a programmable logic controller, and / or other electronic, preferably programmable, circuit.

[0144] Preferably, the electronic circuit is configured to receive measurement data from the sensor component and / or to send control signals, for example control commands, to the heating element in order to generate the heat field.

[0145] Preferably, the electronic circuit can be configured to regulate the heating element depending on the measurement data from the sensor component. Preferably, the electronic circuit is configured to issue a command to generate the heat field to the heating element after a measurement by the sensor component, for example, to increase, maintain, or decrease the heat output.

[0146] In preferred embodiments, the electronic circuit can also be configured to process the measurement data recorded by the sensor component with regard to the modulation of the heat field. Processing data preferably means that the electronic circuit is configured to perform computational operations and / or computational steps, for example, with recorded measurement data from the sensor component. In particular, the electronic circuit can be used to determine the difference between a baseline heat flow value and the measurement data measured at the sensor component.

[0147] The electronic circuit can thus be implemented as an evaluation, readout, and / or control electronics unit, which enables control of the heating element, readout of the sensor component, and / or evaluation of the measured data. If an evaluation is performed, the electronic circuit can also be referred to as a processing unit.

[0148] The term "computing unit" preferably refers to any device or unit that can be configured to perform computing operations. The computing unit is preferably, for example, a processor, a processor chip, a microprocessor, and / or a microcontroller, which is preferably configured to evaluate the modulation of the thermal field. The computing unit can also preferably be a programmable circuit board. The computing unit can also preferably comprise a computer-usable or computer-readable medium, such as a hard disk, random access memory (RAM), read-only memory (ROM), flash memory, etc.

[0149] Method steps for determining the at least one flow parameter of the fluid, as described herein, are preferably carried out by the electronic circuit or computing unit. The phrase "configured to" preferably means that computer code and / or software is installed on the electronic circuit or computing unit to carry out the method step, for example, to check the extent to which a modulation of the heat field was induced and which parameters of the fluid were decisive for this. The computer code and / or software for evaluating the modulation of the heat field can be written in any programming language or a model-based development environment, e.g., in C / C++, C#, Objective-C, Java, Basic / VisualBasic, MATLAB, Simulink, StateFlow, Lab View, and / or Assembler.

[0150] The computer code and / or software, which is preferably installed on the electronic circuit or processing unit, in particular to evaluate the modulation of the thermal field, can be considered technical features because a direct physical effect of the thermal sensor, for example, the supply of a control signal for a heating element or the detection of a temperature change by the sensor component, is utilized. Functional descriptions of the computer code and / or software can therefore be considered preferred and defining embodiments of the invention.

[0151] In a further aspect, the invention relates to a system comprising a) a sensor package as described above or a sensor package arrangement as described above and b) a fluidic connection, wherein the fluidic connection enables a connection to a main channel so that the fluid can flow from the main channel via the inlet region into the sensor package and via the outlet region from the sensor package back into the main channel.

[0152] A fluidic connection refers to a connecting component through which a fluid can flow. In the context of the invention, the fluidic connection enables, in particular, a transition of the fluid from a main channel into the sensor package. The transition refers, in particular, to an entry of the fluid from the main channel into the sensor package or into the sensor package arrangement and an exit of the fluid from the sensor package or from the sensor package arrangement back into the main channel. Thus, the fluidic connection defines a flow path for the fluid between the main channel and the sensor package or the sensor package arrangement.

[0153] This advantageously allows optimization of the flow path between a main channel and the region of the system in which the measurement of at least one flow parameter is to be performed. In particular, potential flow turbulence can be reduced or avoided, allowing a targeted, sensitive, and thus reliable measurement to be carried out. In a further preferred embodiment, the system is characterized in that the fluidic connection is connected to the sensor package via the base plate or via the cover, wherein at least one opening for providing an inlet region or an outlet region of the sensor package is connected to the fluidic connection via the sealing material (see also Figs. 8, 9).

[0154] Thus, the sealing material can advantageously achieve a sufficiently stable connection between the fluidic connection and the sensor package.

[0155] For example, it may be preferred that the sensor package comprising a sensor chip and a base plate is connected to a main board. The main board can be attached to the base plate or the cover. The main board preferably has main board openings. The fluidic connection can preferably be connected to the main board in such a way that a transition of the fluid from the main channel leads through the fluidic connection and then via the inlet region into the flow channel of the sensor package. The fluid can then leave the sensor package via the main board opening and the fluidic connection via the outlet region and return to the main channel. The electronic circuit can preferably be connected to the main board, which is connected to the sensor chip, in particular the thermal sensor, for controlling the heating element and / or evaluating the temperature response.

[0156] It may also be preferred for the sensor package to be directly connected to a fluidic connector without a main board being attached as an intermediate component. The connection of the sensor package to the fluidic connector can be enabled via the base component or the cover (see also Fig. 9 for a direct attachment of a fluidic connector to a cover of the sensor package).

[0157] The fluidic connection preferably comprises a component that allows the fluid to flow into openings, for example, openings in the sensor package and / or mainboard openings. The fluidic connection can preferably comprise one, two, or more connection regions designed to be connected to the openings in the sensor package and / or mainboard openings, in particular to thereby also provide a fluid connection. The fluidic connection can preferably be formed by one or more pipes and / or hoses. The fluidic connection preferably comprises a material selected from a group comprising plastic, plastic, metal, and / or glass.

[0158] In a further aspect, the invention relates to the use of a sensor package as described above, a sensor package arrangement as described above, or a system as described above for measuring a flow parameter of a fluid in a main channel in a bypass configuration.

[0159] The average person skilled in the art recognizes that explanations, technical features, definitions and advantages of the sensor package, the sensor package arrangement and / or the system described above as well as preferred embodiments of the aforementioned also apply to use in a bypass configuration, and vice versa. A bypass configuration preferably refers to the attachment of a side channel (or bypass) to a main channel into which the fluid to be measured can flow. In the context of the invention, the flow channel of the sensor package forms the bypass or a partial section thereof. A main channel in combination with a sensor package according to the invention or a sensor package arrangement according to the invention, whose flow channel forms the bypass or a partial section thereof, is also referred to as a bypass configuration in the context of the invention.

[0160] In a bypass configuration, the fluid to be detected or measured flows within the main channel. The bypass is fluidically connected to the main channel, allowing the fluid to be introduced from the main channel into the bypass and returned from the bypass back to the main channel. Furthermore, a bypass configuration preferably includes a flow restrictor within the main channel.

[0161] Preferably, a flow restrictor is incorporated in the main channel and a fluidic connection between the sensor package and the main channel is provided such that the inlet region of the sensor package adjoins a region of the main channel upstream of the flow restrictor, while the outlet region of the sensor package adjoins a region of the main channel downstream of the flow restrictor, so that a pressure difference across the flow restrictor can be measured based on a flow of the fluid through the flow channel of the sensor package.

[0162] The flow restrictor causes a pressure drop, resulting in a pressure difference, particularly between a region of the main channel at the inlet of the sensor chip (upstream of the flow restrictor) and a region of the main channel at the outlet of the sensor chip (downstream of the flow restrictor). Due to the pressure difference, the fluid enters the bypass, with the magnitude of the pressure difference determining the flow velocity through the bypass. The fluid flows from the main channel into the bypass and from the bypass back into the main channel.

[0163] The flow restrictor increases flow resistance within the main channel, resulting in a pressure difference. This can arise, without being limited to theory, from two effects. Firstly, the friction between the fluid and the surfaces of the flow restrictor (surfaces parallel to the flow) leads to a pressure drop that increases essentially linearly with the flow. Secondly, the end surfaces and their edges generate turbulence and thus a pressure drop that increases essentially quadratically with the flow. A pressure / flow characteristic curve therefore preferably includes a combination of linear and quadratic components.

[0164] A flow restrictor can preferably be selected from a group comprising a measuring orifice (flow restrictor) and / or a Venturi nozzle. It can also be preferred for the flow restrictor to comprise a honeycomb structure or a blade structure. The flow restrictor preferably comprises a surface area that is as large as possible and is directed parallel to the flow direction within the main channel, and a cross-section that is as small as possible. The bypass in particular provides a fluidic connection between the sensor package and the main channel such that the inlet region of the sensor package borders on a region of the main channel upstream of the flow restrictor. The outlet region of the sensor package, in turn, borders on a region of the main channel that borders downstream of the flow restrictor. Upstream and downstream are preferably related to the direction of the fluid flow in the main channel.Positioning the inlet area upstream means that the inlet area is located upstream of the flow restrictor in the direction of fluid flow, while the outlet area is located downstream of the flow restrictor in the direction of fluid flow in the main channel. The pressure difference across or along the flow restrictor in the main channel can thus be measured by the sensor chip inside the bypass.

[0165] The fluid flows from the main channel into the bypass. This is primarily due to the fact that the pressure at the inlet of the main channel is higher than at the outlet. This pressure difference results from the flow restrictor in the main channel and depends on the flow behavior of the fluid in the main channel, such as the flow velocity.

[0166] Within the bypass, the sensor package, particularly the thermal sensor, can detect the influence of the fluid on the thermal field via the temperature response. This can be used, for example, to determine the flow behavior within the fluid's flow channel.

[0167] The temperature response, for example, is sensitive to the flow velocity in the flow channel. Since the flow velocity in the bypass is directly related to the flow-dependent pressure difference in the main channel, this allows information about the flow in the main channel. The thermal sensor can also obtain other properties or flow parameters of the fluid, such as heat capacity and / or thermal conductivity. This enables monitoring not only of the flow behavior of the fluid in the main channel, but also of its composition.

[0168] The aspects of the invention will be described below by way of example with reference to figures, without being limited to these descriptions.

[0169] Figures

[0170] Short description of the characters

[0171] Fig. 1 - 6 Schematic representation of preferred embodiments of the sensor package.

[0172] Fig. 7 Schematic representation of a preferred embodiment of the flow sensor arrangement.

[0173] Fig. 8-9 Schematic representation of a preferred embodiment of a system according to the invention. Detailed description of the figures

[0174] Fig. 1 shows a preferred embodiment of the sensor package 1. The sensor package 1 comprises a sensor chip 3 for measuring at least one flow parameter of a fluid, a base plate 5 and a cover 19.

[0175] For this purpose, a sensor chip 3 with a thermal sensor (not shown) is provided on a base plate 5, which is closed by a cover 7 in the form of a cap.

[0176] A flow channel 7 is formed within the sensor chip 3. The thermal sensor comprises a heating element for providing a thermal field and a sensor component for detecting a temperature response of the thermal sensor as a function of the influence of the fluid flowing in the flow channel 7 on the thermal field.

[0177] Preferably, the thermal sensor can be positioned on a membrane, which is held by a support structure made of a substrate 4. A cavity 17 is located beneath the membrane with the thermal sensor, with the flow channel 7 extending at least partially within the cavity 17 beneath the thermal sensor.

[0178] For the inlet and outlet of a fluid to be measured, the sensor package 1 comprises openings 13, which in the embodiment shown are incorporated in the base plate 5. One of the openings 13 serves to provide an inlet region 9, and the other opening serves to provide an outlet region 11. Inlet and outlet regions 9 and 11 correspond to the section of the sensor channel 7 that runs within the substrate 4 of the sensor chip 3.

[0179] On an outer side of the sensor package 1, the openings are laterally enclosed by a sealing material 15.

[0180] Advantageously, the sealing material 15 achieves a stable and fluid-tight attachment, whereby the sealing material 15 can enable a connection between the sensor package 1, in particular the sensor chip 3, and an application, e.g., a mainboard and / or a fluidic connection. In particular, the sealing material 15 can be applied using simple methods proven in the prior art, so that a person skilled in the art does not require a great deal of effort to prepare the sensor package 1. Furthermore, the sensor package 1 according to the invention advantageously achieves significant cost savings.

[0181] Another advantage here is the fact that the sealing material 15 can fulfill multiple functions. For example, in addition to mechanical fixation and fluidic sealing, an electrical contact option can also be offered by selecting an electrically conductive material for the sealing material 15. Thus, the sealing material 15 not only enables a simple, mechanically stable and fluid-tight connection to a main flow channel whose fluid is to be measured, but can also simultaneously ensure an electrical connection of the electronic components contained in the sensor package 1, such as a thermal sensor 3 and / or an electronic circuit to an external circuit carrier, for example a main circuit board. Furthermore, the sealing material 15, particularly if it comprises an elastic material, can also additionally provide resilience.This can be particularly advantageous in the case of strong fluid flows in order to achieve damping.

[0182] In the field of MEMS microphones, it is known to attach a solder ring for a so-called bottom-port configuration for MEMS microphones to a circuit board. The solder ring can enclose an area attached to the sound inlet opening for MEMS microphones and is intended, in particular, to serve as an acoustic seal. According to the invention, it was recognized that a concept that is at least partially similar enables a simplified connection of flow sensors to the respective application.

[0183] This was by no means obvious, as flow sensors and MEMS microphones differ in their intended use and structural design, and the solder ring of MEMS microphones primarily serves as an acoustic seal. However, the application of a sealing material, which provides an opening on the side and outside of a sensor package for thermal flow measurement, represents a departure from conventional approaches in the field of flow sensors and a significant simplification of packaging.

[0184] Figs. 2 - 4 show further preferred embodiments of the sensor package 1. The sensor package 1 comprises a sensor chip 3 and a base plate 5, as well as a cover 19. The flow channel 7 is formed within the sensor package 1. In the embodiments, the flow channel 7 runs from the inlet region 9 to the outlet region 11 outside the sensor chip 3, which can in particular comprise a thermal sensor (not shown) on a membrane above a cavity 17.

[0185] In the embodiment according to Fig. 2, the openings 13 for providing the inlet region 9 and the outlet region 11 are each introduced into the base plate 5. The sealing material 15 laterally encloses the openings 13 on the outside of the sensor package (or in this case, an outside of the base plate 5).

[0186] In the embodiment according to Fig. 3, the opening 13 for providing an entry area 9 is provided in the base plate 5. The opening 13 for providing an exit area 11 is provided in the cover 19. The sealing material 15 laterally encloses the openings 13 on the outside of the sensor package, in particular on an outside of the base plate 5 and the cover 19.

[0187] In the embodiment according to Fig. 4, the openings 13 for providing the inlet region 9 and the outlet region 11 are introduced into the cover 19. The sealing material 15 laterally encloses the openings 13 on an outer side of the sensor package (or here an outer side of the cover 19).

[0188] Fig. 5 shows a further preferred embodiment of the sensor package 1. The sensor package 1 comprises a sensor chip 3, a base plate 5, and a cover 19. Analogous to the embodiment of Fig. 3, an opening 13 for providing an inlet region 9 is introduced into the base plate 5, while an opening 13 for providing an outlet region 11 is introduced into the cover 19. The sealing material 15 laterally encloses the openings 13 on the cover 19 and the base plate 5 on an outer side of the sensor package.

[0189] Deviating from the embodiment of Fig. 3, however, the flow channel 7 runs at least partially through the sensor chip 3, in particular through a cavity 17 above which a thermal sensor (not shown) is located on a membrane.

[0190] For this purpose, the inlet region 9 is located directly below the cavity 17, and an aperture 29 in the sensor chip 3 forms a section of the flow channel 7. The aperture 29 can be formed, for example, by an opening in the membrane on which the thermal sensor is located. The thermal sensor preferably comprises a heating element and a temperature sensor mounted in sufficient proximity to the aperture 29, preferably such that the aperture 29 is located between the heating element and the temperature sensor. This allows a particularly strong influence of the fluid on the thermal field provided by the heating element to be utilized to perform a sensitive measurement.

[0191] Fig. 6 shows a further preferred embodiment of the sensor package 1. The sensor package 1 comprises the sensor chip 3 and the base plate 5 as well as a cover 19.

[0192] Analogous to the embodiment of Fig. 5, the flow channel 7 extends at least partially through the sensor chip 3, in particular through a cavity 17 above which a thermal sensor (not shown) is located on a membrane. For this purpose, the inlet region 9 is again located below the cavity 17, and an aperture 29 in the sensor chip 3 forms a section of the flow channel 7. The aperture 29 can be formed, for example, by an opening in the membrane on which the thermal sensor is located.

[0193] Deviating from the embodiment of Fig. 6, the outlet area 11 is not located in the cover 19, but in the base plate 5.

[0194] Fig. 7 shows a preferred embodiment of a sensor package arrangement 21. The sensor package arrangement 21 comprises a sensor package 1 and a main board 25. The sensor package 1 is installed on the main board 25. Furthermore, the main board 25 has main board openings 25. The openings 13 for providing an inlet region 9 and an outlet region 11 of the sensor package 1 are connected to the main board openings 33 via the sealing material 15. The sealing material 15 is preferably designed as a solder ring, so that it can simultaneously serve as an electrical contact in addition to providing a fluidic seal.

[0195] The sensor package arrangement 21 further comprises an electronic circuit 31 configured to determine the at least one flow parameter based on a measurement by the sensor component. The electronic circuit 31 is mounted on the main circuit board 25. By providing the solder ring 15, the sensor package 1 can advantageously be provided as an SMD component, enabling a direct connection of the sensor package 1 to the main circuit board 25 by means of surface mounting. Advantageously, it is not necessary to implement, for example, wire connections, etc., thus enabling a more compact installation. Fig. 8 shows a preferred embodiment of a system 37. The system 37 comprises a sensor package arrangement 21 comprising a sensor package 1 installed on a main circuit board 25, as well as a fluidic connection 23.The fluidic connection 23 enables a connection to a main channel 27, so that the fluid can flow from the main channel 27 via the inlet area 9 into the sensor package 1 and via the outlet area 11 from the sensor package 1 back into the main channel 27. For this purpose, the fluidic connection 23 is connected to the sensor package 1 via the main board 25 or its main board openings 33. The openings 13 for providing the inlet area 9 or the outlet area 11 of the sensor package 13 are in turn connected to the main board 25 via the sealing material 15, preferably as a solder ring.

[0196] The system 37 is used in a bypass configuration in which the flow channel 7 of the sensor package 1 forms the bypass 41 or a partial section thereof.

[0197] For this purpose, a flow restrictor 39 is introduced into the main channel 27. A fluidic connection between the sensor package 1 and the main channel 27 is provided such that the inlet region 9 of the sensor package 1 borders a region of the main channel 27 upstream of the flow restrictor 39, while the outlet region of the sensor package 11 borders a region of the main channel 27 downstream of the flow restrictor 39.

[0198] The flow restrictor 39 causes a pressure drop, in particular a pressure difference, to occur, in particular in a region of the main channel 27 at the inlet area 9 and in a region of the main channel 27 at the outlet area 11. The pressure difference allows the fluid to enter the bypass 41. The fluid flows from the main channel 27 into the bypass 41 and from the bypass 41 back into the main channel 27.

[0199] Within the bypass 41, the sensor package 1, in particular the thermal sensor, can detect the influence of the fluid on the thermal field via the temperature response. This can be used, for example, to determine the flow behavior within the fluid's flow channel. Since the flow velocity in the bypass 41 is directly related to the flow-dependent pressure difference in the main channel 41, this provides information about the flow in the main channel 27.

[0200] Fig. 9 shows, analogous to Fig. 8, another preferred embodiment of a system 37 in a bypass configuration. The system 37 comprises a sensor package 1 and a fluidic connection 23 for connection to a main channel 27. Unlike the embodiment of Fig. 8, the sensor package 1 is not located on a main circuit board. Instead, the fluidic connection 23 is connected to the cover 19 of the sensor package via openings 13. The openings 13 in the cover for providing the inlet area 9 or the outlet area 11 of the sensor package 13 are laterally enclosed by the sealing material 15 to ensure a stable and fluid-tight connection to the fluidic connection 23. List of Reference Symbols

[0201] 1 sensor package

[0202] 3 Sensor chip

[0203] 4 Substrat

[0204] 5 Base plate

[0205] 7 Flow channel

[0206] 9 Entrance area

[0207] 11 Exit area

[0208] 13 Opening

[0209] 15 Sealing material, solder material

[0210] 17 Cavity

[0211] 19 Cover

[0212] 21 Sensor package arrangement

[0213] 23 Fluidic connection

[0214] 25 Motherboard

[0215] 27 Main Canal

[0216] 29 aperture

[0217] 31 Electronic circuit

[0218] 33 Mainboard opening

[0219] 37 systems

[0220] 39 flow restrictors

[0221] 41 Bypass Bibliography

[0222] Kuo, Jonathan TW, Lawrence Yu, and Ellis Meng. "Micromachined thermal flow sensors - A review." Micromachines 3.3 (2012): 550-573.

[0223] Palmer, Kristoffer, et al. "A highly integratable silicon thermal gas flow sensor." Journal of Micromechanics and Microengineering 22.6 (2012): 065015.

[0224] Lee, Y. C., Ramesh Ramadoss, and Nils Hoivik. "Introduction to MEMS packaging." Mems Packaging 5 (2018): 1 .

Claims

PATENT CLAIMS 1. Sensor package (1) comprising a sensor chip (3) for measuring at least one flow parameter of a fluid, a base plate (5) and a cover (19), wherein the sensor package (1) has openings (13) on the cover (19) and / or the base plate (5) for providing an inlet region (9) and an outlet region (11) for the fluid, so that a flow channel (7) is formed within the sensor package (1), and wherein the sensor chip (3) further comprises a thermal sensor comprising a heating element for providing a thermal field and a sensor component for detecting a temperature response of the thermal sensor as a function of an influence of the fluid flowing in the flow channel (7) on the thermal field, characterized in that at least one opening (13) on an outer side of the sensor package (1) is laterally enclosed by a sealing material (15).

2. Sensor package (1) according to the preceding claim, characterized in that the sealing material (15) laterally encloses the at least one opening (13) in an annular manner and forms a sealing ring.

3. Sensor package (1) according to one or more of the preceding claims, characterized in that the sealing material (15) comprises a solder material, a bonding material, an adhesive and / or a plastic, preferably an elastomer.

4. Sensor package (1) according to one or more of the preceding claims, characterized in that the sealing material (15) comprises a solder material which is present as a solder ring, wherein the solder material preferably comprises a material selected from a group comprising tin, zinc, copper, silver, gold, their compounds and / or alloys.

5. Sensor package (1) according to one or more of the preceding claims, characterized in that the sealing material (15) provides an electrical connection which can be used for an electrical connection.

6. Sensor package (1) according to one or more of the preceding claims, characterized in that the base plate (5) is in the form of a semiconductor substrate or a circuit carrier, preferably a printed circuit board.

7. Sensor package (1) according to one or more of the preceding claims, characterized in that the cover (19) is present as a cap or as a cover substrate, wherein the cover (19) preferably comprises a material selected from a group comprising a dielectric, a semiconductor, a conductor and / or combinations thereof, wherein the dielectric is preferably selected from a group comprising silicon nitride, silicon dioxide, aluminum oxide, aluminum nitride, polyimide and / or a polymeric material, wherein the semiconductor is preferably selected from a group comprising monosilicon, polysilicon, germanium and / or chalcogenide and / or wherein the conductor is preferably selected from a group comprising aluminum, titanium, zinc and / or a noble metal, preferably selected from a group comprising gold, platinum, iridium, palladium, osmium, silver, rhodium and / or ruthenium.

8. Sensor package (1) according to one or more of the preceding claims, characterized in that the sensor component is formed by a temperature sensor, wherein the temperature sensor is preferably selected from a group comprising a thermocouple, a diode, a thermistor and / or a thermopile and / or the heating element is an electrical heating element, preferably a heating resistor, wherein the thermal sensor preferably comprises two temperature sensors.

9. Sensor package (1) according to one or more of the preceding claims, characterized in that the sensor chip (3) has a membrane on which the thermal sensor is positioned, wherein the membrane preferably comprises an electrically conductive material and / or a dielectric material, wherein the electrically conductive material is preferably selected from a group comprising semiconductors and / or metals, in particular silicon, polysilicon, graphene, chalcogenide, and / or wherein the dielectric material is preferably selected from a group comprising silicon nitride, silicon dioxide, aluminum oxide, aluminum nitride, polyimide and / or a polymeric material.

10. Sensor package (1) according to one or more of the preceding claims, characterized in that the sensor chip (3) has a cavity (17), above which a membrane extends, on which the thermal sensor is positioned, wherein preferably the sensor chip has an aperture (29) which is preferably attached to the membrane, wherein furthermore the aperture (29) is present as a section of the flow channel (7) or the flow channel (7) runs at least partially within the cavity (17).

11. Sensor package (1) according to one or more of the preceding claims, characterized in that the flow channel (7) runs within the sensor package (1) and the inlet region (9) and the outlet region (11) of the flow channel (7) are present through openings (13) on the base plate (5) and / or the cover (19).

12. Sensor package (1) according to one or more of the preceding claims, characterized in that the sensor chip (3) has a substrate (4), wherein the thermal sensor is positioned on a front side of the substrate (4) and at least a section of the flow channel (7) is formed below the thermal sensor within the substrate (4), which was formed starting from a back side of the substrate by partially removing the substrate (4), wherein the substrate (4) is preferably designed monolithically.

13. Sensor package arrangement (21) comprising a. a sensor package (1) according to one of the preceding claims and b. a main board (25), characterized in that the sensor package (1) is installed on the main board (25).

14. System (37) comprising a) a sensor package (1) according to one or more of the preceding claims 1 - 12 or a sensor package arrangement (21) according to claim 13 and b) a fluidic connection (23), wherein the fluidic connection (23) enables a connection to a main channel (27) so that the fluid from the main channel (27) via the inlet region (9) into the Sensor package (1 ) and can flow back into the main channel (27) via the outlet area (11 ) from the sensor package (1 ).

15. Use of a sensor package (1) according to one or more of the preceding claims 1 - 12, a sensor package arrangement (21) according to claim 13 or a System (37) according to claim 14 for measuring a flow parameter of a fluid in a main channel (27) in a bypass configuration.

Images