Force sensor architecture

Abstract

The invention relates to a force sensor architecture. The described technology relates to a force sensor package comprising a force sensor and a temperature sensor combined in a monolithic integrated circuit. The force sensor package may also include other components, such as memory and on-board processing circuitry (e.g., microcontroller), which allow temperature compensation to be performed on the force measurement signal generated by the force sensor. Force sensors including integrated deformable bodies, such as planar springs, are also described. Various types of deformable bodies are described to which a force sensor chip is coupled. Structures and coupling between the force sensor chip and the deformable body help generate stresses of different values in two orthogonal directions in the force sensor chip in response to an applied force.

Description

TECHNICAL FIELD

[0001] The aspects described herein generally relate to force sensors, and more particularly, to force sensor packages and various architectures thereof. BACKGROUND

[0002] Force sensors can be used in various applications, such as in the automotive industry, for example, for measuring braking forces. However, conventional force sensors implement sensor elements, such as strain gauges, that are physically small and thus difficult to mount to a deforming body to measure an applied force. Mounting of force sensor elements also presents significant difficulties, as asymmetries between the sensor elements can amplify errors in the measured force, and the material to which the sensor elements are mounted needs to be carefully considered to ensure that the measured stress / strain is due to the applied force. For example, conventional force sensors are affected by temperature changes, as various sensor components can have different coefficients of thermal expansion and thus expand at different rates, introducing additional strain that can cause errors in the force measurement. Thus, conventional force sensors have various disadvantages in their implementation and use. SUMMARY

[0003] Likewise, applications such as the automotive industry can implement force sensors or other sensors, particularly for braking systems or other subsystems that are critical to driving safety. Typically, the oil pressure of a hydraulic braking system can be measured to determine the applied force, verifying proper operation of the braking system. For example, such a hydraulic braking system can utilize a brake booster, where a sensor is placed within a reservoir to monitor the level of hydraulic fluid, which would detect leaks in the system.

[0004] However, as vehicles tend to drive with more electrical power in their operation, the established purely mechanical parts of the braking system will be replaced by electromechanical braking (EMB) components. Such EMB systems can use a braking system where a motor pushes a lever to actuate a brake disc. These newer EMB systems are only electrically connected to the brake shoe, avoiding the use of hydraulic fluid. To date, there is no specific force sensor for this application, and thus as one example of an application, the embodiments described herein enable a force sensor to be mounted directly on the brake shoe or other location, such that the force sensor measures the force due to the deformation of the object it is coupled to.

[0005] Further, the embodiments described in Section II can implement a force sensor package that implements an integrated deformable body, such as a planar spring (e.g., with a particular geometry). Thus, the force sensor packages described in Section II implement various geometries of the deformable body integrated to the force sensor package, which enables measurement of either the in-plane shear stress (sigXY) or the difference in the in-plane normal stress components (sigxx - sigyy) caused by an applied force. Additionally, the deformable body can be captured within the sensor package in a particular manner, and the sensor element can be wire-bonded in a particular manner at the center of the deformable body, affecting the geometry of the deformable body. The deformable body and the applied load / force are also clamped in a manner that allows for improved sealing of the sensor element. BRIEF DESCRIPTION OF DRAWINGS

[0006] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the aspects of the present disclosure and, together with the description, further serve to explain the principles of the aspects and to enable a person skilled in the relevant art to make and use the aspects.

[0007] FIG. 1A illustrates an example first force sensor package architecture according to embodiments of the present disclosure;

[0008] FIG. 1B illustrates an example second force sensor package architecture according to embodiments of the present disclosure;

[0009] FIG. 2 illustrates an example output of a force sensor package measuring an applied force according to embodiments of the present disclosure;

[0010] FIG. 3 illustrates an example physical-mechanical interface between a force sensor package and a deformable body according to embodiments of the present disclosure;

[0011] FIG. 4A-4C illustrates an example of an electrical interface between a force sensor package and an external device according to embodiments of the present disclosure;

[0012] FIG. 5A illustrates a first view of a portion of an example force sensor package according to embodiments of the present disclosure;

[0013] FIG. 5B illustrates a second view of a portion of an example force sensor package according to embodiments of the present disclosure;

[0014] FIG. 6A illustrates an example block diagram of a force sensor chip including electronic circuitry and external connections according to embodiments of the present disclosure;

[0015] FIG. 6BAn example electronic circuit including a PMOS force sensor element is illustrated according to an embodiment of the present disclosure;

[0016] FIG. 6C An example electronic circuit including an NMOS force sensor element is illustrated according to an embodiment of the present disclosure;

[0017] FIG. 6D The illustration shows an embodiment of the present disclosure, regarding... FIG. 6B and FIG. 6C Additional details regarding the orientation of the stress sensor element shown;

[0018] FIG. 7 The illustration shows an example of deformation of a deformable body in response to a force applied in the normal direction on the surface of a force sensor chip, according to an embodiment of the present disclosure.

[0019] FIG. 8 An example finite element (FEM) numerical simulation illustrating the stability of in-plane stress components according to an embodiment of the present disclosure is shown.

[0020] FIG. 9 The illustration depicts an example deformable attractive force according to an embodiment of the present disclosure;

[0021] FIG. 10 The diagram shows a deformation of the force sensor package, which is caused by thermally induced stress generated by the attraction force at each corner of the deformed body.

[0022] FIG. 11 The diagram illustrates the process of... FIG. 10 The shear stress on the surface of the force sensor chip caused by thermally induced stress is shown.

[0023] FIG. 12 The illustration shows an example of bonding lead wiring and placement for a force sensor chip according to an embodiment of the present disclosure;

[0024] FIG. 13A-13C The illustrations show alternative variant shapes according to embodiments of the present disclosure;

[0025] FIG. 14A The illustration shows a variant of the H shape according to an embodiment of the present disclosure;

[0026] FIG. 14B The illustration shows an embodiment of the present disclosure, such as FIG. 14A The H-shaped deformable body shown is an example of deformation in response to a force applied in the normal direction on the surface of the force sensor chip;

[0027] FIG. 14C The illustration shows alternative variations of the H-shape according to embodiments of the present disclosure;

[0028] FIG. 15 Alternative deformation body shapes and force sensor package structures are illustrated in accordance with embodiments of the present disclosure;

[0029] FIG. 16A-16B Alternative deformation body shapes and force sensor package structures are illustrated in accordance with embodiments of the present disclosure;

[0030] FIG. 17 An example configuration in which a force sensor chip is mounted to a PCB placed between the force sensor chip and a deformation body is illustrated in accordance with embodiments of the present disclosure;

[0031] FIG. 18 Alternative U-shaped deformation bodies are illustrated in accordance with embodiments of the present disclosure;

[0032] FIG. 19 Example deformations of a U-shaped deformation body in response to a force applied normal to the surface of a force sensor chip are illustrated in accordance with embodiments of the present disclosure; FIG. 18

[0033] FIG. 20 An example configuration in which a force sensor chip is sealed as part of a force sensor package is illustrated in accordance with embodiments of the present disclosure.

[0034] Example aspects of the present disclosure will be described with reference to the accompanying drawings. The drawings, in which like reference numerals refer to like elements throughout, generally illustrate the aspects described herein. The drawings and description provided herein are intended to be illustrative and explanatory rather than restrictive. DETAILED DESCRIPTION

[0035] In the following description, numerous specific details are set forth to provide a thorough understanding of the various aspects of the disclosure. However, it will be apparent to one skilled in the art that the aspects, including the structural, system, and method aspects, can be practiced without these specific details. The description and representation herein are used to enable others skilled in the art to best utilize the present disclosure in conjunction with the existing technology, and to best enable the practice of the aspects, including the structural, system, and method aspects. In other instances, well-known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring aspects of the disclosure.

[0036] ​For ease of explanation, the embodiments herein are presented in two separate sections. The first section relates to the use of a force sensor package that includes a force sensor and a temperature sensor combined in a monolithic integrated circuit. The force sensor package can also include other components, such as memory and on-board processing circuitry (e.g., a microcontroller) that allow for temperature compensation to be performed on force measurement signals generated by the force sensor. Section II, for example, relates to force sensor packages that include an integrated deformable body, such as a planar spring. The force sensor packages discussed in Section II can utilize different types of uniquely shaped deformable bodies to which a force sensor chip is coupled. The structure and coupling between the force sensor chip and the deformable body facilitates the generation of normal stresses in the force sensor chip in two orthogonal directions having different values in response to a force applied normal to the surface of the force sensor chip. Additionally, the manner in which the force sensor package is constructed and the coupling arrangement between the deformable body and the force sensor chip allows for a reduction in the number of sensor elements and provides various mounting options. The shape of the deformable body can also facilitate coupling particularly short bond wires to the force sensor chip, thereby simplifying manufacturing design and reducing cost.

[0037] While embodiments of force sensor packages are discussed separately in each section, it should be noted that any of the embodiments described in either Section I or Section II can be combined with one another, and any of the architectures, deformable bodies, sensor elements, force sensor chips, and / or techniques described in Section I are also applicable to the embodiments described in Section II, and vice versa. For example, any of the embodiments described herein with respect to force sensor package Section I can optionally be implemented as any appropriate portion of the force sensor package embodiments described in Section II.

[0038] I. Single-chip force sensor package with temperature regulation

[0039] Similarly, existing force sensors rely on changes in a mechanical deformable body to measure an applied force. For example, an applied force can push down on a steel membrane, causing a strain near the anchor of the membrane. This strain is typically measured at four locations in a Wheatstone bridge configuration, however, complicating its design and use. Accordingly, the embodiments discussed in this section relate to an integrated force sensor package that can provide additional functionality compared to conventional force sensors while facilitating a simplified mounting process given its monolithic design. The force sensor package can include a force sensor chip that can be mounted directly to a deformable body (e.g., a brake shoe), for example, depending on where the strain is to be measured. The force sensor package can include one or more force sensor elements that can be implemented as any suitable type of material having an electrical parameter that changes in response to an applied force.

[0040] FIG. 1AAn example first force sensor package architecture according to an embodiment of the present disclosure is illustrated. FIG. 1A The force sensor package 100 shown includes a force sensor 102 (e.g., a force sensor element as discussed in further detail herein), a temperature sensor 104, analog-to-digital converters (ADCs) 106 and 108, processing circuitry 110, a memory 112, and a data interface 114. FIG. 1B An example second force sensor package architecture according to an embodiment of the present disclosure is illustrated. Besides using ADCs 106, 108, and 154, respectively... FIG. 1A and 1B The force sensor packages 100 and 150 shown are identical to each other. Therefore, regarding FIG. 1A Any statement in the description of the force sensor package also applies. FIG. 1B The force sensor packages, and vice versa, are further explained in this paper, where the differences between these force sensor packages are further pointed out.

[0041] The force sensor package 100 can be implemented as a monolithic integrated circuit, which includes, for example, FIG. 1A Additional, fewer, or replaceable components are shown. The force sensor package 100 can therefore include, for example, a monolithic application-specific integrated circuit (ASIC). The force sensor package 100 can alternatively be referred to as a force sensor chip. As discussed in further detail below, the force sensor package 100 is configured to perform temperature compensation on the measurement provided by the force sensor 102 using a temperature measurement provided by the temperature sensor 104. Furthermore, FIG. 1A The arrows shown can indicate any suitable number and / or type of connection between the various components of the force sensor package 100, which may include buses, leads, conductive traces, etc.

[0042] like FIG. 1A The force sensor package 100 shown includes a force sensor 102. The force sensor 102 can include any suitable type of force sensor, including known types. The force sensor may alternatively be referred to herein as a strain sensor, stress sensor, or strain / stress sensor. In this context, it should be understood that it is assumed that Young's modulus (a mechanical property of a solid material that measures tensile or compressive stiffness when a force is applied longitudinally) is a predefined parameter known about the operation of the force sensor package 100. For example, the Young's modulus of the force sensor package 100 can be known from the material on which the force sensor package 100 is placed, or derived from experimental testing prior to the operation of the force sensor package 100.

[0043] In any case, the force sensor 102 can be configured to generate a force measurement signal that is derived from a strain imparted to the sensor package as a result of the object deforming due to the applied force. However, the force sensor 102 can additionally or alternatively generate a force measurement signal that is derived from a stress imparted to the sensor package as a result of the object deforming due to the applied force, with the understanding that the relationship between stress and strain is a known Young’s modulus constant for the force sensor package 100 as described above.

[0044] The force sensor 102 can be implemented with any suitable number and / or type of strain or stress elements configured to measure strain and / or stress, including known types in which the measured strain or stress is output as a corresponding force measurement signal in either case. For example, the force sensor 102 can be implemented as one or more resistors, transistors, or xMR-based sensor elements that output a force measurement signal indicative of strain and / or stress resulting from an applied force. To provide additional examples, the force sensor 102 can be implemented as a metal oxide semiconductor field effect transistor (MOSFET) current mirror that can include two or more orthogonal PMOS or NMOS elements that deliver a current that is a function of stress imparted in one or more directions resulting from an applied force. The strain and / or stress that is introduced into the force sensor elements 102 and measured as a force measurement signal results from an applied force that deforms the body to which the force sensor package 100 is coupled, as discussed further herein. In the example of an EMB system as noted above, the body to deform can be a brake shoe that deforms when braking, although embodiments are not limited to this application or to this particular type of body to deform.

[0045] With continued reference to FIG. 1A , the force sensor 102 outputs the force measurement signal as an analog voltage or current value that can be within any suitable range of values depending on the particular application. The force sensor 102 is configured to generate the force measurement signal continuously or according to any suitable measurement sampling rate, and thus the force sensor package 100 can output force measurement data as discussed herein in either case. The force measurement signal output by the force sensor 102 is coupled to an analog-to-digital converter (ADC) 106. The ADC 106 can include an ADC having any suitable resolution that is configured to transform the analog force measurement signal into a digital value that includes any suitable number of bits. The digital force measurement signal is then coupled to a processing circuitry 110 for further processing as discussed in further detail below.

[0046] The temperature sensor 104 can be placed within the force sensor package 100, proximate to the force sensor 102, and thus the temperature measurement signal can be indicative of a measured temperature of a region of the force sensor package 100 that is also proximate to the force sensor 102. The temperature sensor 104 can be implemented with any suitable number and / or type of temperature sensor element and / or accompanying circuitry to generate a temperature measurement signal indicative of a measured temperature. For example, the temperature sensor 104 can include one or more negative temperature coefficient (NTC) thermistors, one or more resistance temperature detectors (RTDs), a PN junction of a bipolar transistor, one or more thermocouples, one or more semiconductor-based sensors (e.g., utilizing a same diode with temperature sensitive voltage-to-current characteristics), etc.

[0047] The temperature sensor 104 outputs the temperature measurement signal as an analog voltage or current value, which can be within any suitable range of values depending on the particular application. The temperature measurement signal output by the temperature sensor 104 is coupled to an analog-to-digital converter (ADC) 108. The ADC 108 can include an ADC with any suitable resolution, and is configured to transform the analog temperature measurement signal into a digital value including any suitable number of bits. The ADC 108 can be the same as the ADC 106, or alternatively, the ADC 106, ADC 108 can operate using different bit resolutions, different reference voltages and / or currents, or differ in their configuration and / or operation. The digital temperature measurement signal is then coupled to processing circuitry 110 for further processing, as discussed in further detail below.

[0048] Referring now to FIG. 1B , the force sensor package 150 includes a single ADC 154 rather than separate ADCs 106, 108 as shown in FIG. 1A . For the force sensor package 150, the ADC 154 can operate in the same manner with respect to digitization of the received force measurement signal and temperature measurement signal. However, for the force sensor package 150, the force sensor 102 and the temperature sensor 104 share the ADC 154. Thus, the ADC 154 can receive the force measurement signal and the temperature measurement signal at different times, sharing a common connection between the force sensor 102 and the temperature sensor 104. This can be implemented, for example, using time-division multiplexing (TDM) of the received force measurement signal and temperature measurement signal. The sampling rate and period of each of the force measurement signal and the temperature measurement signal output by the force sensor 102 and the temperature sensor 104 can be synchronized with one another, for example, according to a predetermined asynchronous timing schedule or in response to any suitable clock signal (not shown).

[0049] The processing circuitry 110 can be implemented as any suitable number and / or type of components configured to execute machine-readable instructions, perform processing operations, or otherwise execute various functionalities as discussed herein. To this end, the processing circuitry 110 can be implemented as, for example, one or more processors and / or cores, any suitable number and / or type of special-purpose hardware components (such as microcontrollers, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), system-on-chip (SoC), dedicated logic, and / or other circuitry), and / or the like.

[0050] The memory 112 can comprise any suitable type of non-transitory computer- readable medium, such as volatile memory, non-volatile memory (e.g., electrically erasable programmable read-only memory (EEPROM)), or a combination of these. To the extent that the processing circuitry 110 implements a software-based solution to perform various functionalities discussed herein, this can be implemented, for example, via the processing circuitry 110 accessing the electrical parameters 112.1 and executing instructions stored in the temperature compensation control module 112.2.

[0051] Accordingly, the processing circuitry 110 can execute computer-readable instructions stored in the temperature compensation control module 112.2 to perform any of the various functionalities discussed in further detail herein with respect to generating force measurement data for the force sensor package 100. Alternatively, the processing circuitry 110 can use hardware components (such as adders, bit shifters, logic components, and / or the like) to perform the various functionalities discussed in further detail herein. According to such embodiments, the processing circuitry 110 can access the electrical parameters 112.1 stored in the memory 112 to perform such operations.

[0052] Although the memory 112 is shown in FIG. 1A in an example manner and for ease of explanation. As FIG. 1A indicated, the memory 112 can be integrated as part of the processing circuitry 110. Additionally or alternatively, the memory 112 can be implemented in addition to the integrated memory of the processing circuitry 110, and in such cases, any of the data stored in the memory 112 can alternatively be stored in the memory that is integrated as part of the processing circuitry 110, and vice versa.

[0053] In any case, the electrical parameters 112.1 can represent any suitable electrical parameters associated with the force sensor 102 and / or the temperature sensor 104. The processing circuitry 110 can thus utilize the electrical parameters 112.1 to generate temperature-corrected force measurement data using one or more of the stored electrical parameters, as further discussed below. For example, changes in temperature will introduce errors into the force measurement signals generated by the force sensor 102 due to heat-induced strain. The processing circuitry can access the electrical parameters 112.1 to compensate for this temperature error.

[0054] To this end, the electrical parameters 112.1 can represent any suitable information about the operational characteristics of the force sensor 104 or other components of the force sensor package 102 as a function of temperature. This information can be derived, for example, based on calibrated force measurements or other measurements performed at different temperatures, which can be performed prior to operation of the force sensor package 100. For example, the electrical parameters 112.1 can include thermal operating curves representing strain or stress data measurements of the force sensor 102 and / or data identifying strain or stress measurement offsets related to respective operating temperatures. As an additional example, the electrical parameters 112.1 can include information about temperature coefficients of reference voltages used by the ADC 106 and / or the ADC 108.

[0055] In any case, the processing circuitry 110 can access the electrical parameters 112.1 to map a measured temperature to a corresponding strain or stress measurement offset value. The processing circuitry 110 can then use this strain or stress offset to compensate for temperature errors in the received digital force measurement signals. Additionally, the processing circuitry 110 can utilize temperature coefficients of reference voltages used by the ADC 106 to further compensate the received digital force measurement signals, which can include, for example, compensating for voltage drift by offsetting the received digital force measurement signals by a digital bit value related to the current temperature measurement. Thus, when receiving the digital force measurement signals, the processing circuitry 110 uses a temperature measurement signal indicative of the temperature of the force sensor 102 (or at least proximate to the temperature of the force sensor 102) to generate temperature-corrected force measurement data. Likewise, this temperature-corrected force measurement data compensates for temperature errors introduced in the force measurement signals and / or the ADC 106.

[0056] The electrical parameters 112.1 can additionally represent any appropriate data that can be used to compensate temperature measurements provided by the temperature sensor 104. For example, the electrical parameters 112.1 can include any appropriate information to enable relative changes in force measurement data to generate temperature-corrected force measurement data. As one example, this can include calibration to an external reference temperature sensor and / or system temperature. Thus, any appropriate data representing such an external temperature can be included as part of the electrical parameters 112.1.

[0057] In various embodiments, the processing circuitry 110 can provide digital data to a data interface 114, which is configured to output the digital data to an external device, such as a microcontroller, electronic control unit, etc. The data interface 114 can also enable the force sensor package 100 to receive data from the external device, which can include, for example, control and / or configuration data. Thus, the data interface 114 can be implemented as any appropriate number and / or type of components to facilitate the force sensor package 100 transmitting data and / or receiving data from an external device, as discussed herein. For example, the data interface 114 can include any appropriate number of ports, pins, drivers, bond pads, leads, buffers, etc. In various embodiments, one or more portions of the data interface 114 can be integrated with the processing circuitry 110. Thus, the data interface 114 can include external connections (e.g., bond pads) of the force sensor package 100 and / or internal connections from the processing circuitry 110 and / or within the processing circuit 110 within the force sensor package 100, or any appropriate combination thereof that enables data to be communicated as noted herein.

[0058] Additionally or alternatively, the data interface 114 can output the force measurement data as an analog signal. To this end, the processing circuitry 110 can include any appropriate type of analog driver circuitry configured to output the force measurement data as an analog value (e.g., a voltage value or a current value) transmitted via the data interface 114. Additionally or alternatively, the force sensor package 150 can include any appropriate number of digital-to-analog converters (DACs), which can have any appropriate bit resolution. These DACs may, for example, be implemented as part of the processing circuitry 110 and / or the data interface 114, or as separate components (not shown) between the processing circuitry 110 and the data interface 114. Thus, the force sensor package 150 can output the force measurement data via the data interface 114 as a digital signal (e.g., as shown) and / or as an analog signal representing these values via an analog signal scheme. FIG. 2

[0059] As FIG. 1A ​As shown, the digital data can include force measurement data, which can include temperature corrected force measurement data as discussed above. Alternatively, the force measurement data can include data indicative of an applied force that has been calculated by the processing circuitry 110. That is, the force measurement data can include data indicative of an applied force that has been calculated by the processing circuitry 110 from temperature corrected force measurement data. Alternatively, the temperature corrected force measurement data can be transmitted as the force measurement data, with additional calculations converting the temperature corrected force measurement data to force measurement data offloaded to an external device to determine the applied force.

[0060] To provide an illustrative example, the processing circuitry 110 can receive a digital force measurement signal from the ADC 106, which can include stress or strain measurements performed by the force sensor 102 that have been digitized as described above. The processing circuitry 110 can then perform temperature compensation on the digital force measurement signal to provide temperature corrected strain or stress data. Again, regardless of the type of sensor, the processing circuitry 110 can convert between stress and strain using Young’s modulus. The processing circuitry 110 can then use, for example, the temperature corrected strain measurements to obtain temperature corrected stress measurements. FIG. 2 An example of such strain measurement is shown in the middle, which maps digital values to a range of micro-strain measurements. Once a stress measurement is calculated, the resulting calculation can be multiplied by an area over which the measurement is performed to convert to a force measurement (stress = force / area). For example, the area can correspond to a surface of the force sensor package 100 that is coupled to the deformable body. Alternatively, the temperature corrected stress or strain measurements can be generated as force measurement data that is transmitted to an external device that then performs the force calculation.

[0061] In either case, it should be noted that given the implementation of the processing circuitry 110 on the board, the overall force sensor package 100 can advantageously be coupled to the deformable body. This is in contrast to conventional practices where only the force sensor 102 is mounted to the deformable body, in which case it is preferable to avoid stress and strain being introduced into other parts of the structure where the sensor is mounted, which would otherwise introduce errors. Thus, given the larger area of the force sensor package 100, this allows for an easier setup process, and this can be performed via the use of the processing circuitry 110 as well as the mechanical architecture of the force sensor package 100, which will be discussed in further detail below.

[0062] FIG. 3 An example physical mechanical interface between the force sensor package and the deformable body according to embodiments of the present disclosure is illustrated. For clarity, in FIG. 3The force sensor 102 is shown as being physically positioned on the force sensor package 100, 150, but it should be understood that the force sensor 102 is integrated within and as part of the force sensor package 100, 150. Thus, the force sensor 102 can not necessarily be physically positioned on the force sensor package 100, 150 as shown. As FIG. 3 The force sensor package 100, 150 is shown as being directly bonded to the deformer 302 via a bonding material 304. The deformer 302 can include any suitable type of body that can deform as part of a particular application, where the deformation introduces stress and strain into the force sensor package 100, 150, and in turn, the force sensor 102. For example, the deformer can include a brake shoe that forms part of an EMB system as noted above.

[0063] The bonding material 304 can include any suitable type of material used according to any suitable bonding process to ensure that the stress / strain resulting from the deformation of the deformer 302 is transferred into the force sensor package 100, 150 and the force sensor 102. For example, the force sensor package 100, 150 can be placed on the deformer 302 using a bonding process such as glass frit bonding or a similar metallurgical process. The use of glass frit bonding or a similar metallurgical process is particularly useful because these processes ensure very good strain transfer from the carrier material to the force sensor package 100. This strain can then be translated into stress that can be detected by the force sensor 102, for example.

[0064] As an illustrative example, when a force is applied to the deformer 302, the deformer 302 is caused to elongate. This strain is transferred into the force sensor package 100, 150 via the bonding material 304. Again, the relationship between strain ε and stress σ is defined via the material-specific Young's modulus E according to σ = εE. Thus, this correlation can be used because the Young's modulus E of the force sensor package 100, 150 can be known in advance, and thus the correlation between force and stress is also known.

[0065] FIG. 3 The use of bond pads 306 is also illustrated, which are shown as being placed on the force sensor package 100, 150. The force sensor 100, 150 can include any suitable number of bond pads 306, which can include or be electrically coupled to the data interface 114, as shown in FIG. 1A and FIG. 1B The bond pads 306 as shown in FIG. 3 may be indicated with external connections as shown in FIG. 1A and FIG. 1B

[0066] FIG. 4A-4C ​An example of an electrical interface between a force sensor package and an external device according to embodiments of the present disclosure is illustrated. In FIG. 4A-4C , it is shown that the force sensor package 100, 150 can be connected to any suitable type of substrate 404, which can include a printed circuit board FR4, etc. For clarity, the interposer is not shown in FIG. 4A-4C , but can be coupled to the force sensor package 100, 150 at the opposite side of the bond pads 306 in each case.

[0067] For example, as shown in FIG. 4A , the bond balls 402 can be used to solder or otherwise electrically couple the force sensor package 100, 150, which is then flipped and directly coupled to the substrate 404 in this manner. Thus, for this mechanical configuration, each of the bond pads 306 is coupled to the substrate 404 via a corresponding one or more bond balls 402. The substrate 404 can include, for example, a PCB that includes one or more connections to an external computing device. Although any number of such electrical cables can be implemented for this purpose, in the example shown in FIG. 4A , a single electrical cable 406 is shown. For example, as shown in FIG. 4A-4C , the force sensor package 100, 150 can include an embedded wafer-level ball grid array (eWLB) whose backside is exposed to facilitate the shown bonding process.

[0068] Alternatively, as shown in FIG. 4B , the force sensor package 100, 150 can be connected to the substrate 404 via bond wires 422. For example, and as shown in FIG. 4B , the bond wires 422 can be used to directly electrically couple the bond pads 306 of the force sensor package 100, 150 to corresponding bond pads 408 of the substrate 404. Thus, each of the bond pads 306 is coupled to the substrate 404 via one or more corresponding bond wires 422 that are coupled to a corresponding bond pad 408. Each bond pad 408, in turn, is coupled to a corresponding electrical cable 406 via a bridge connection 410. Again, the substrate 404 can include, for example, a PCB that includes one or more connections to an external computing device. Although any suitable number of electrical cables can be implemented to electrically couple the force sensor package 100, 150 to an external device in this manner, in the example shown in FIG. 4B , a single electrical cable 406 is shown.

[0069] As another example, FIG. 4C embodiments in which the force sensor package 100, 150 is partially embedded within the substrate 404 are illustrated. The electrical connections shown in FIG. 4C are the same as those shown in FIG. 4B , although in the case of the former the force sensor package 100, 150 is partially embedded within the substrate 404.FIG. 4C In the illustrated embodiment, the substrate 404 includes holes or recesses as FIG. 4C illustrated, and the force sensor package 100, 150 is inserted into the hole and thus covered by the substrate 404. Additionally, the substrate 404 can be modified so that the force sensor package 100, 150 can be fully embedded within the substrate 404, thereby further increasing the mechanical connection between the force sensor package 100, 150 and the substrate 404.

[0070] II. Force sensor package with integrated deformable body

[0071] As noted above, this section relates to a force sensor package that implements an integrated deformation body and addresses problems associated with conventional force sensors as further described herein. However, the force sensor package in this section can include a force sensor die, which can include force sensor elements and other optional components, as well as additional components such as an integrated deformation body. Thus, the force sensor die described in Section I can be synonymous with a force sensor package, while the force sensor die described in Section II can be considered in some embodiments to be a part of a force sensor package.

[0072] In any case, it should be noted that conventional force sensor package designs can implement an integrated spring / deformation body that deflects under an applied force to be measured. Strain gauges can then be glued or otherwise fixed to the deformation body so that their resistance changes due to the applied strain. The strain gauges are typically connected in a Wheatstone bridge fashion, which is powered by a voltage circuit and whose output is connected to an amplifier. The small output voltage of the bridge is thus amplified and corrected for temperature drift and offset, and then output.

[0073] However, as noted above, thermal-induced stresses can introduce errors in force measurements, which in this design can be caused by a difference in the coefficient of thermal expansion (CTE) between the strain gauges and the integrated spring. As one illustrative example, assume that the strain gauges are glued to the spring at 25°C, the spring has a CTE of 15 ppm / °C, and the strain gauges have a CTE of 10 ppm / °C. At 26°C, the spring expands 5 ppm more than the strain gauges, and thus the strain gauges appear to output the deflection of the spring, but this deflection is not present (i.e., not due to an applied external force to be measured). This results in a temperature-dependent zero-point error in force measurements.

[0074] Conventionally, and with reference to the illustrative example above, this error is managed by fine-tuning the temperature coefficient of the strain gauge resistor to -5 ppm / °C, which roughly compensates for the additional 5 ppm / °C of CTE mismatch between the spring and the strain gauge. However, the accuracy of this approach is limited, and the strain gauge resistor must be matched to the CTE mismatch between the spring and the strain gauge, i.e., for each spring material, a dedicated strain gauge material or tempering process is required. In other words, the CTE of the strain gauge resistor is fine-tuned by a tempering process rather than by a change in material or alloy composition.

[0075] Additionally, conventional strain gauge based force sensors require four strain gauge elements, which complicates their design and increases cost. Embodiments of the force sensor package described in further detail in this section can reduce the use of such sensor elements by implementing at least two strain / stress sensitive electronic devices. These strain / stress sensitive electronic devices can also be referred to herein as force sensor elements, strain sensor elements, stress sensor elements, or strain / stress sensor elements. The force sensor elements form part of a force sensor chip and respond differently to at least one strain / stress component. An integrated deformable body on which the force sensor chip is mounted can generate different in-plane stress component values in different directions in response to an applied force, and the force sensor elements can be arranged orthogonally to each other to exploit this feature.

[0076] The force sensor package also includes sensor circuitry, which is alternatively referred to herein as electronic circuitry, and converts the electrical parameters of the force sensor elements into a force measurement signal in response to an applied force. The force sensor elements can have any suitable implementation, as discussed in further detail herein. For example, the force sensor elements can include: strain gauges aligned in two different directions, metal resistors placed on a substrate surface in two different directions, piezoresistive resistors, piezoelectric MOSFETs (e.g., arranged in a current mirror configuration), Hall effect devices, capacitors aligned in two different directions on a semiconductor chip, etc. The two different directions may, for example, include orthogonal directions, as shown in further detail in this section.

[0077] Due to the orthogonal arrangement between the force sensor elements, the force sensor elements are configured to measure in-plane shear stress (sigXY) or the difference between in-plane normal stress components (sigXX - sigYY) in / near the main X-Y surface of the force sensor chip and near the center of the chip surface. To facilitate these measurements, the force sensor chip including at least the force sensor elements can be rigidly fixed (e.g., glued or otherwise bonded) to a deformable body (e.g., a spring) included as part of the force sensor package.

[0078] As discussed in further detail in this section, the deformable body can have a particular geometry that utilizes symmetry and / or rotational symmetry, as well as other unique shapes, to induce only sigXY or sigXX-sigYY when the applied force to be measured causes the deformable body to deflect. Additionally, the deformable body can be clamped or otherwise fixed at a particular location within the force sensor package and supported by sliding contact surfaces on opposite sides to prevent measurement errors due to thermal expansion. Furthermore, the deformable body can have a slot shape with wires of the force sensor package running into (e.g., routed through) the slots to reduce the overall length of the coupled bond wires. The force sensor package can include a lower housing and an upper housing, which can alternatively be referred to as“halves,” and which seal the force sensor elements. Both of these halves can be loosely coupled to one another (in a mechanical sense) and can optionally be coupled to one another via a mechanism having a spring constant that is significantly smaller (e.g., 1 / 10, 1 / 100, etc.) than the spring constant of the integrated deformable body of the force sensor chip placed. Such a loose coupling arrangement is particularly useful to facilitate a snap-type sealing and assembly process of the force sensor package.

[0079] A. Use of two-dimensional body to prevent temperature-induced measurement error

[0080] Likewise, conventional force sensors can include strain gauges mounted to a spring that measure the applied force by deformation of the spring caused by the applied force. However, such strain gauges are typically implemented as metal grids with long, thin parallel traces, and thus their resistance increases if the long traces are lengthened due to strain of the spring in the longitudinal direction. However, if the spring expands perpendicular to the longitudinal direction, the strain gauges do not respond or respond very little. This leads to problems with thermal strain, as a single strain gauge cannot distinguish between measured strain in the longitudinal direction due to an external force or thermal expansion.

[0081] In contrast, embodiments described in this section involve the use of a two-dimensional body, referred to herein as a force sensor chip, which can also simply be referred to herein as a sensor chip and includes two or more force sensor elements, which can also be referred to herein as sensor elements. The two or more force sensor elements FIG. 5AA force sensor element (not shown in FIG. 5, but which can also be placed in the center of the force sensor chip 502) can be embedded within and / or proximate to a top surface or a bottom surface of the force sensor chip 502. The force sensor chip 502 can include a semiconductor chip having any suitable number of components, which are discussed in further detail herein. The force sensor element can include any suitable type of components, each of which includes an electrical parameter that differentially responds to an orthogonal in-plane stress component of the deformable body 504 introduced due to an applied force, which can be perpendicular to a surface of the force sensor chip 502, as discussed further herein. To this end, the deformable body 504 can have a geometry and configuration such that two different normal stress values are generated in two orthogonal directions in response to the applied force. Further, the force sensor element can be oriented, for example, perpendicular to each other and aligned parallel to edges of the force sensor chip 502 in order to measure these different normal stress values. Additional details regarding the geometry and operation of the force sensor element are provided further below.

[0082] FIG. 5A An example of such a force sensor chip is shown in FIG. 5, which includes a portion of a force sensor package 500 as shown. The force sensor package 500 can include additional components than those discussed herein, fewer components, or alternative components. For example, the force sensor package 500 can include the force sensor chip 502, the deformable body 504, various supports 506, 508, a lower housing 510.1 and an upper housing 510.2 (see FIG. 5B ), and any other suitable components that can facilitate the full sealing and operation of the force sensor package 500.

[0083] For example, the force sensor package 500 includes the force sensor chip 502 coupled to a center of the deformable body 504. The force sensor chip 502 can be directly coupled to the deformable body 504 in this manner using any suitable bonding technique, such as, for example, an adhesive, a solder (solder paste, solder wire, diffusion solder), brazing, welding, etc. The force sensor chip 502 can be attached to the deformable body 504 along a fully planar major (e.g., bottom) surface of the force sensor chip 502, with an opposite (i.e., top) side of the force sensor chip 502 in FIG. 5A FIG. 5. Alternatively, the force sensor chip 502 can be coupled to the deformable body 504 via an intermediate substrate, such as a printed circuit board, which can increase the physical robustness of the force sensor package 500 to applied forces, as discussed further herein.

[0084] The deformable body 504 can comprise any suitable type of material to ensure proper deflection and generation of in-plane stress components in response to applied forces, as discussed herein. The deformable body 504 can have any suitable thickness to ensure desired stiffness and deformation in response to applied forces. Additionally, the deformable body 504 can have a uniform thickness, or alternatively, a variable thickness with respect to different regions. For example, the deformable body 504 can have a center portion (e.g., where the force sensor chip 502 is placed) that is thicker or thinner than the outer arms (e.g., where the supports 506.1, 506.2, 508.1, 508.2 are located, as discussed herein). It is particularly useful for the deformable body 504 to be thicker in the center region to provide additional protection to the force sensor chip 502 from breaking.

[0085] As some illustrative examples, the deformable body 504 can comprise a metal (e.g., spring steel, bronze, CuBe, etc.). As additional illustrative examples, the deformable body 504 can comprise FR4 material, glass, plastic / polymer / hard plastic / thermoplastic / resin / Kapton, ceramic, fiberglass or carbon fiber layers, Kevlar, etc. To provide additional illustrative examples, the deformable body 504 can comprise a multi-layer laminate. For example, the deformable body 504 can be composed of a lower steel spring and an upper FR4 spring, where the layers are joined to each other in any suitable manner (e.g., glued, bonded, bolted, riveted, etc.), or alternatively, the layers can be loosely stacked such that the layers can slide laterally with respect to each other, where the former provides a stiffer composite material than the latter. It should be noted that the different CTEs of the layers can cause a bow, but since this is isotropic (e.g., the same in all lateral directions), it does not affect the sigXY or sigXX-sigYY measurements performed by the force sensor chip 502.

[0086] The force sensor chip 502 can have a square shape or any other suitable shape, where the thickness of the force sensor chip 502 is significantly smaller (e.g., 10%, 1%, 1%, etc.) than the length and width dimensions of the force sensor chip 502. As an illustrative example, the force sensor chip 502 can have a regular size of approximately 1 mm x 1 mm x 0.1 mm. However, as discussed in further detail below, it is particularly useful for the force sensor chip 502 to have a square shape so as to not support a stress in one direction that is more than a stress in another perpendicular direction.

[0087] In any case, given the two-dimensional nature of the force sensor chip 505, stress from the biaxial state of the deformable body 504 can be effectively coupled into the force sensor chip 502. This stress can be caused by a force applied to the force sensor package 500 in the normal direction to the surface of the force sensor chip 502. Furthermore, due to two or more force sensor elements forming part of the force sensor chip 502, the force sensor chip 502 is configured to generate one or more force measurement signals in response to an applied force that causes deformation of the deformable body 504 and results in one or more measurement signals, which are measured by changes in the electrical parameters of the force sensor elements. These one or more measurement signals indicate the measurement of the in-plane stress component. In this way, the force sensor chip 502 outputs at least one force measurement signal indicating the measurement of the in-plane stress component sensed in the deformable body 504.

[0088] To illustrate the in-plane stress components measured in this way via the force sensor chip 502, it is useful to provide a reference coordinate system. Therefore, continuing to refer to... FIG. 5A The force sensor chip 502 can primarily occupy the xy-plane relative to this coordinate system, such that the measured in-plane stress components are defined by the alignment of the force sensor chip 502 with respect to the x-axis and y-axis of the xy-plane. For example, for FIG. 5A In the illustrated embodiment, the x-axis and y-axis are parallel to the edge of the force sensor chip 502. Therefore, it should also be noted that although the embodiment is not limited to this arrangement, the force sensor elements of the force sensor chip 502 can be placed perpendicular to each other and parallel to the edge of the force sensor chip 502 (e.g., aligned with the x-axis and y-axis).

[0089] Continuing this example, the force sensor package 500 can be mounted for a specific application such that the force applied to the force sensor package 500 is in the normal direction to the surface of the force sensor chip 502, for example, primarily in the -z direction. Additionally, the deformable body 504 may include two lines of symmetry that... FIG. 5A The axis is also labeled as the '1' axis and the '2' axis. Therefore, for FIG. 5A In the embodiment shown, the xy axis is rotated 45 degrees from axis 1-2, which is associated with the line of symmetry of deformable body 504.

[0090] Considering the coordinate system and configuration, now consider as follows: FIG. 5AThe arrangement and coupling between the force sensor chip 502 and the deformable body 504 shown, for example, when the x-y axes are rotated 45 degrees from the 1-2 axes associated with the line of symmetry of the deformable body 504. In this case, the force sensor chip 502 can detect an in-plane shear stress component (i.e., sigXY) of the deformable body 504 in response to an applied force in the -z direction. However, if the force sensor chip is rotated such that the x-y axes are aligned with the 1-2 axes associated with the line of symmetry of the deformable body 504, then the pure shear stress becomes a biaxial normal stress state with sigXX = -sigYY and zero shear stress. Thus, measuring sigXY by the shear stress sensor is the same as measuring sigXX - sigYY in the 45° rotated frame. In other words, the force sensor chip 502 can be configured to measure in-plane stress components of the deformable body 504 parallel to the chip edges or along the chip diagonals based on the manner in which the force sensor chip (and its accompanying force sensor elements) is aligned with the geometry of the deformable body 504.

[0091] In other words, the force sensor elements can be placed on the force sensor chip 502 as noted herein, and one or more measurement signals provided by the force sensor elements facilitate detection of sigXX and sigYY (or, alternatively, sigXX - sigYY and sigXX + sigYY). That is, if the deformable body 504 is deflected in the x direction, then a positive sigXX and a small negative sigYY (due to Poisson contraction) is induced on the force sensor chip 502. However, if the deformable body 504 is heated, then it expands in the x and y directions in a predominantly uniform manner. Thus, the force sensor chip 502 detects a very small sigXX - sigYY and a much larger sigXX + sigYY, from which it can then be inferred that no external force is acting on the deformable body 504. In this manner, temperature-dependent zero-point errors for force measurements are avoided by the force sensor package 500 as discussed herein.

[0092] It should be noted that instead of the force sensor elements of the force sensor chip 502, conventional strain gauges can be used by orienting the strain gauges perpendicular to each other and using electronic circuitry to compare the resistance of the two strain gauges in response to an applied force. For example, if one strain gauge is aligned with the x-direction and the other strain gauge is aligned with the y-direction, uniform strain in both directions results in the same change in resistance of both strain gauges (Rx / Ry ~ constant), and deflection of the deformable body 504 in the x-direction increases Rx and slightly decreases Ry (thus Rx / Ry increases). For example, Rx and Ry can be implemented as metal resistors placed on top of the force sensor chip 502 without using the aforementioned force sensor elements. However, it should be noted that metal resistors change very little with stress (about 1% / GPa in silicon), whereas the mobility in other types of force sensor elements described herein, such as low-doped resistors or MOSFETs in single silicon crystals, for example, respond to stresses of about 20-50% / GPa in silicon. Another problem with using conventional strain gauges is the precise relative alignment of the two strain gauges and their large size compared to the much smaller microelectronic devices. Thus, the use of the two-dimensional force sensor chip 502 and its accompanying force sensor elements as discussed in this section can be particularly advantageous to address these issues.

[0093] B. Various shapes and implementations of integrated deformable body

[0094] In FIG. 5A the deformable body 504 is shown as a planar spring having a cross shape, although this is by way of example and not limitation, and embodiments as discussed herein can include deformable bodies 504 having any suitable shape, as discussed in further detail below. However, it can be particularly useful to implement deformable bodies having symmetry or rotational symmetry, as discussed in further detail herein. Referring now to FIG. 5A the shape of the deformable body 504 shown, the deformable body 504 can include a cross shape having four arms of equal length, and can include rounded corners or slots as shown positioned with each of the arms.

[0095] The force sensor package 500 also includes an upper housing 510.2 and a lower housing 510.1, the upper housing 510.2 being placed on a first side of the deformable body 504 and the lower housing 510.1 being placed on a second side of the planar spring opposite the first side. In other words, the upper housing 510.1 and the lower housing 510.2 can be substantially parallel to each other, except for manufacturing tolerances. To ensure that forces are coupled into the force sensor package 500, the deformable body 504 can have any suitable number of supports 506, 508, and any of these supports 506, 508 can be coupled to one of the upper housing 510.1 and the lower housing 510.2, for example as shown in FIG. 5A and 5BAs shown, it can be a function of a particular shape of deformable body 504. Therefore, either of the supports 506, 508 as discussed herein can be alternatively referred to as a force coupler, which is configured to introduce stress into deformable body 504 by deformation (e.g., bending) of deformable body 504, as discussed in further detail herein.

[0096] For example, such as FIG. 5A The deformable body 504 shown may include a first support member 506.1, a second support member 506.2, a third support member 508.1, and a fourth support member 508.2. For ease of illustration, when given support members 506.1, 506.2 are adjacent to the upper housing 510.2, support members 506.1, 506.2 may be referred to herein as an upper support pair, and when given support members 508.1, 508.2 are adjacent to the lower housing 510.1, support members 508.1, 508.2 may be referred to herein as a lower support pair. Support members 506.1, 506.2 and 508.1, 508.2 may each be formed as part of the deformable body 504, for example, by bending or otherwise forming the respective portions of the deformable body 504 via any suitable manufacturing process. In this configuration, the deformable body 504 and any of the supports 506.1, 506.2 and 508.1, 508.2 can form a single, integral component. In other embodiments, the supports 506.1, 506.2 and 508.1, 508.2 can include separate components fixed to their respective portions of the deformable body 504 via any suitable joining process (such as adhesive, brazing, welding, etc.). In other embodiments discussed in further detail below, one or more of the supports 506.1, 506.2 can be formed as part of the upper housing 510.2. Additionally or alternatively, one or more of the supports 508.1, 508.2 can be formed as part of the lower housing 510.1. Embodiments may also include combinations of these configurations. For example, one of the support members 506.1, 506.2, 508.1, and 508.2 may be formed as part of the upper housing 510.1 or the lower housing 510.2, while the other of the support members 506.1, 506.2, 508.1, and 508.2 may be formed as part of the deformable body 504.

[0097] In any case, and as stated above, the deformable body 504 can be shape-symmetrical, having 90-degree rotational symmetry, and includes... FIG. 5AThe lines of symmetry are labeled as the '1' and '2' axes. Because the supports 506.1, 506.2 and 508.1, 508.2 are implemented to couple applied forces into the deformable body 504, which will be discussed in further detail below, the supports 506.1, 506.2 and 508.1, 508.2 can be placed on the deformable body 504 according to these lines of symmetry. By way of example, each of the supports 506.1, 506.2 and 508.1, 508.2 can be placed at a distal end of each respective one of the four arms of the deformable body 504, as shown in FIG. 5A

[0098] In this arrangement, each of the supports 506.1, 506.2 is placed at a respective position on the deformable body 504 opposite one another with respect to a first line of symmetry of the deformable body 504, which in this example can be defined by the '1' axis, as shown in FIG. 5A Additionally, each of the supports 508.1, 508.2 is arranged at a respective position on the deformable body 504 opposite one another with respect to a second line of symmetry of the deformable body 504, which in this example can be defined by the '2' axis, as shown in FIG. 5A The first and second lines of symmetry can be orthogonal to one another.

[0099] Accordingly, an applied force, which can likewise be applied in a normal direction to a surface of the force sensor chip 502, can be distributed to the deformable body 504 via each of the supports 506.1, 506.2 and 508.1, 508.2. As discussed in greater detail below, because the force sensor chip 502 is coupled to the deformable body 504, this also results in a stress being generated in the force sensor chip 502, which can be measured via the force sensor elements discussed herein. In this way, when a force is applied to the force sensor package 500 in a normal direction to a surface of the deformable body 504, the arrangement between the force sensor chip 502, the deformable body 504, and each of the supports 506.1, 506.2 and 508.1, 508.2 results in in-plane normal stresses being generated in the force sensor chip 502 in two orthogonal directions with different values. Also, because the force sensor chip 502 can be placed at a center of the deformable body 504, the force sensor chip 502 is positioned away from distal ends of the arms of the deformable body 504 at which the force is coupled to the deformable body 504. Accordingly, the stress measured by the force sensor package 500 is less affected by misplacement of the force sensor chip 502 on the deformable body 504.

[0100] ​Likewise, the force sensor chip 502 can include two (or more) force sensor elements, which can be used to measure stresses induced into the force sensor chip 502 due to an applied force, which can then be measured by the force sensor chip 502. To this end, and as noted above, the force sensor chip 502 can include two force sensor elements placed perpendicular to one another, each having an electrical parameter that differentially responds to orthogonal in-plane stress components induced into the deformable body 504 due to an applied force.

[0101] Additionally, to measure the applied force, the force sensor chip 502 can include an electronic circuit configured to generate a force measurement signal. This force measurement signal can be generated, for example, from one or more measurement signals based on changes in the electrical parameters in each of the sensor elements in response to stresses distributed into the deformable body due to the applied force. As discussed in further detail herein, these measurement signals can be indicative of different types of in-plane stress components. For example, the measurement signals can include stress measurement signals indicative of in-plane shear stress (sigXY) or the difference in in-plane normal stress components (sigXX - sigYY). The types of in-plane stress components that can be measured in this manner can be a function of various factors, such as the geometric orientation of the force sensor chip 502 relative to the deformable body 504, the types of force sensor elements, and the type of silicon material used to implement the force sensor elements (or its crystal orientation relative to the surface of a silicon wafer during a semiconductor fabrication process), as discussed in further detail below.

[0102] Details of the electronic circuit and the measurement of the applied force are provided below with reference to FIG. 6A-6C Further details are discussed in further detail below. However, as the functionality of the electronic circuit is dependent on various factors as noted above, it is prudent to provide a brief discussion regarding an exemplary configuration of the force sensor 500 that can be implemented to perform such a measurement of the applied force. Thus, it is noted that to ensure that the applied force is distributed into the force sensor chip 502, one of the supports in the upper support pair can be mechanically coupled to the upper housing 510.2, and one of the supports in the lower support pair can likewise be mechanically coupled to the lower housing 510.1. Although the mechanical coupling configuration of the upper and lower support pairs is not limited to this particular implementation, this particular implementation is used to facilitate explanation in further providing additional examples below to describe the operation of the force measurement sensor 500 in further detail.

[0103] Accordingly, and continuing with this example, which serves as a primary example to describe the operation of force sensor 500, one of the supports 506.1, 506.2 can be mechanically coupled to the upper housing 510.2, which can be subjected to an applied force. Additionally, one of the supports 508.1, 508.2 can be mechanically coupled to the lower housing 510.1. Thus, one of the supports 506.1, 506.2, 508.1, 508.2 can be mechanically coupled to the lower housing 510.1 or the upper housing 510.2, as the case can be, using any suitable joining technique (e.g., adhesive, welding, brazing, etc.).

[0104] According to such embodiments, it can be particularly advantageous to couple a single support of the upper and lower support pairs to its respective lower housing 510.1 or upper housing 510.2, while the other support of the upper and lower support pairs remains mechanically decoupled. For example, only one of the supports 508.1, 508.2 can be mechanically coupled to the lower housing 510.1, while the other of the supports 508.1, 508.2 can remain mechanically decoupled (e.g., unjoined or otherwise fixed). Continuing with this example, only one of the supports 506.1, 506.2 can be mechanically coupled to the upper housing 510.1, while the other of the supports 506.1, 506.2 can remain mechanically decoupled (e.g., unjoined or otherwise fixed). Such an arrangement allows one of the supports of each of the upper and lower support pairs to “float” relative to the lower housing 510.1 or upper housing 510.2, as the case can be. This ensures that thermal expansion of the deformable body 504 does not cause the deformable body 504 to twist due to the attractive forces of all of the supports 506.1, 506.2, 508.1, 508.2, which will be discussed in further detail below. Additionally, in such an arrangement, a force can act on the one of the supports in each of the lower or upper support pairs that is not mechanically coupled to its respective respective lower housing 510.1 or upper housing 510.2.

[0105] Turning now to the operation of the electronic circuitry included as part of the force sensor chip 502, FIG. 6A an example block diagram of a force sensor chip including electronic circuitry and external connections is illustrated, in accordance with an embodiment of the present disclosure. For example, various components of the force sensor chip 502 can be utilized to identify FIG. 6A the illustrated block diagram. Thus, as FIG. 6A illustrated, the force sensor chip 502 can include electronic circuitry 602, at least two force sensor elements 604, which can likewise be placed orthogonally to one another, and a data interface 606.

[0106] Similarly, the sensor element 604 (also referred to herein as a force sensor element) can include any suitable type of force sensor element. Thus, piezoelectric MOSFETs arranged in a current mirror configuration are used to further describe the operation of the electronic circuit 602 by way of example and not limitation below. Similarly, the electronic circuit 602 is configured to generate a force measurement signal from one or more stress measurement signals, which can be indicative of an in-plane stress component resulting from an applied force. As described above, the force measurement signal can include converting a measured stress indicative of an in-plane shear stress (sigXY) or an in-plane normal stress component difference (sigxx - sigyy) to a corresponding force measurement using any suitable technique, including known techniques such as those discussed in Section I above. For example, the force measurement signal can represent a calculation using Young’s modulus and known properties of the force sensor die 502. Alternatively, as described above, the force measurement signal can represent an in-plane shear stress (sigXY) or an in-plane normal stress component difference (sigxx - sigyy), which is then sent to an external device to perform such a calculation.

[0107] In any case, the electronic circuit 602 can provide the force measurement signal to a data interface 606, which is configured to output the force measurement signal to an external device, such as a microcontroller, electronic control unit, or the like. The data interface 606 can also enable the force sensor die 502 to receive data from the external device, which can include, for example, control and / or configuration data. Thus, the data interface 606 can be implemented as any suitable number and / or type of components to facilitate the force sensor die 502 transmitting and / or receiving data from the external device as discussed herein. For example, the data interface 606 can include any suitable number of ports, pins, drivers, bond pads, leads, buffers, or the like. In various embodiments, one or more portions of the data interface 606 can be integrated with the electronic circuit 602. Thus, the data interface 606 can include internal connections within the force sensor die 502 from and / or within the electronic circuit 602 and / or external connections (e.g., bond pads) of the force sensor die 502, or any suitable combination thereof that enables data to be communicated as described herein.

[0108] Examples of the electronic circuit 602 and force sensor element 604 are described in FIG. 6B and 6Care shown in greater detail. Again, the electronic circuit 602 and the sensor elements 604 can form part of the force sensor chip 502, which can be implemented using any suitable type of semiconductor material (e.g., silicon). For ease of explanation, the operation of the electronic circuit 602 and the sensor elements 604 are described herein with respect to standard {100} oriented silicon (due to its common use in CMOS technology), which is used by the force sensor chip 502 as FIG. 6B and 6C indicated in the upper right corner of the diagram, are related to Miller indices. However, for other embodiments, different orientations of silicon can be implemented for the force sensor chip 502, which would modify the operation of the force sensor elements in response to applied forces, as discussed further below.

[0109] Accordingly, as one example, the force sensor chip 502 can be implemented as any suitable type of semiconductor having any suitable crystallographic configuration. For example, the force sensor chip 502 can include a cubic semiconductor (e.g., silicon and germanium) having three mutually perpendicular axes. Two of the crystal axes of the force sensor chip 502 can include in-plane axes that are orthogonal to each other, which can be aligned with the first and second lines of symmetry of the deformable body, as shown in FIG. 6B In this case, a PMOS current mirror configuration can be implemented. The third crystal axis of the force sensor chip 502 can include, for example, a z-axis that is mutually perpendicular to the other two in-plane axes as described above. As another example, the crystal axes of the force sensor chip 502 can be rotated 45 degrees from the first and second lines of symmetry of the deformable body 504 (e.g., rotated around the z-axis or third crystal axis, which can represent the same axis, as described above), as shown in FIG. 6C In this case, an NMOS current mirror configuration can be implemented.

[0110] In addition to using a particular orientation of silicon, the orientation of the force sensor chip 502 relative to the deformable body 504 also affects the operation of the force sensor chip 502, with the resulting stress measurement signals representing different types of orthogonal in-plane stress components in each respective case as described above. For example, the force sensor chip 502 can include a first crystal axis and a second crystal axis, as shown in FIG. 6B and 6CAs shown, they are identified as the x and y axes. The force sensor elements 604 can be placed on the silicon of the force sensor chip that are aligned with these crystal axes, such that the force sensor elements are aligned (e.g., parallel) to the edges of the force sensor chip 502 with respect to the directions that are sensitive to the induced stress. In other words, the force sensor elements 604 can be orthogonal to each other, as discussed in further detail herein. For example, one force sensor element can be placed on the x-axis oriented force sensor chip 502 such that its electrical parameter changes in response to stress on the x-axis, while another force sensor element can be placed on the y-axis oriented force sensor chip 502 such that its electrical parameter changes in response to stress on the y-axis. In this document, "orientation" refers to the direction of the primary current, where "primary" refers to the portion of the current that generates the primary voltage drop in the resistor. For example, in a MOSFET, this would be equivalent to the direction of the current in the channel.

[0111] The operation of the sensor elements 604 and the electronic circuit 602 is described with respect to the orientations shown in FIG. 6B and 6C , in each case assuming standard {100} silicon. It should be noted that in both cases, it is {100} silicon because {100} specifies a wafer plane that is orthogonal to the <100> crystal axis. However, when implementing rotated {100} silicon for the force sensor chip 502, the operation of the force sensor chip 502 can be modified to reverse these use cases. For example, using rotated {010} silicon, the circuit arrangement as shown in FIG. 6C can be used according to the orientation of the first and second lines of symmetry of the deformed body as shown in FIG. 6B , and vice versa.

[0112] Thus, FIG. 6B and 6C the difference between the use cases is that the chip edges in ordinary {100} silicon are aligned as shown in FIG. 6C , while the chip edges in rotated {100} silicon are aligned as shown in FIG. 6B . In other words, the silicon implemented for the force sensor chip 502 can have a set of crystal axes in any suitable direction specified with respect to the crystal (e.g., with respect to the

[100] direction). Thus, the embodiments discussed herein can utilize a force sensor chip 502 having particular axes. For example, these axes can include those from the set of <100> axes (using Miller index notation) that are aligned or rotated (e.g., 45 degrees) with respect to the 1 and 2 axes of the deformed body 504, as shown and discussed with respect to FIG. 6B and 6C in this document.

[0113] As shown in FIG. 6BAs shown, the sensor elements include PMOS transistors Q2 and Q3, which are orthogonally oriented to each other in their physical layout (this is achieved by rotation). FIG. 6B (represented by the transistor symbol in the schematic diagram), and can be aligned with the x and y axes of the force sensor chip 502 as described above, so that the current through the MOSFET channel flows along the silicon single crystal. <110> Directional flow. PMOS transistors Q2 and Q3 may include, for example, piezoelectric MOSFETs, and therefore the electrical parameters responsive to the in-plane stress components introduced into the deformable body 504 may include the current gain of PMOS transistors Q2 and Q3. In such an arrangement, electronic circuitry 602 may include input transistor Q2, which is coupled to a current source and arranged in a current mirror configuration together with sensor element transistor Q3. Therefore, a current signal provided by the current source is input to transistor Q2, which is electrically coupled to transistors Q1 and Q3, causing transistors Q1 and Q3 to output corresponding current signals, as shown. It should be noted that in FIG. 6B In the configuration shown, PMOS transistors Q2-Q3 form one current mirror, and PMOS transistors Q2-Q1 form another. However, Q1 and Q2 have the same orientation, and therefore the current mirror ratio of PMOS transistors Q2-Q1 does not depend on mechanical stress. However, because the PMOS current mirrors formed by PMOS transistors Q2-Q3 are orthogonally oriented relative to each other, the current mirror ratio does depend on mechanical stress.

[0114] In this configuration, the input current I(in) provided by the current source is output from the drain terminal of the force sensor element transistor Q1, and the resulting output current I(out) is output from the drain terminal of the force sensor element transistor Q3. In this configuration, it should be noted that each of transistors Q1 and Q3 responds to stress in both the x and y directions. Therefore, if one of transistors Q1 and Q3 increases its drain current with increasing sigXX, it decreases its drain current with increasing sigYY. Thus, if the other transistor Q1 or Q3 is rotated 90° such that the drain currents through transistors Q1 and Q3 are orthogonal to each other, then by symmetry, the rotated transistor now operates in the opposite manner, i.e., by decreasing its drain current with increasing sigXX and increasing its drain current with increasing sigYY.

[0115] Accordingly, the I(in) and I(out) currents can represent the corresponding stress measurement signals, as discussed herein. And because the x- and y-axes of the force sensor chip are aligned with the 1- and 2-axes of the deformable body 504, the induced stresses do not generate an in-plane shear stress (sigXY), but rather result in generation of in-plane normal stress components sigXXand sigYY. Accordingly, the I(in) and I(out) currents output by the PMOS transistors Q1, Q3 can represent these in-plane normal stress components sigXXand sigYY. In other words, each of the PMOS transistors Q1, Q3 is responsive to both sigXXand sigYY. That is, at a constant gate-source voltage, the drain current increases with sigXXand decreases with sigYY, or the drain current decreases with sigXXand increases with sigYY (depending on its alignment on the x- or y-axis).

[0116] The electronic circuit 602 can also include a differential amplifier 610, and the current signals output by the PMOS transistors Q1, Q3 can be coupled to inputs of the differential amplifier 610, as shown. FIG. 6B Accordingly, the differential amplifier 610 outputs a difference between the in-plane normal stress components sigXXand sigYYas a force measurement signal in this example, in response to a force applied in the normal direction of the surface of the force sensor chip 502.

[0117] Accordingly, the force sensor package 500 is configured to be responsive to an applied longitudinal force with a horizontal induced stress measurement. This is due to the shape and orientation of the deformable body 504 and the manner in which the various portions of the deformable body 504 are mechanically coupled and decoupled with the force sensor package components, as discussed in further detail herein. For example, by coupling the force into the deformable body via the tip (e.g., distal arm), the applied longitudinal force causes the deformable body 504 and the force sensor chip 502 to bend. This bending action enables only the transverse stresses sigXX, sigYYto be introduced into the force sensor chip 502, as discussed herein.

[0118] Turning now to FIG. 6C , the sensor element includes NMOS transistors Q6, Q7, which are oriented orthogonal to one another in physical layout (this is by rotating FIG. 6Ctransistors (as indicated by the symbols of the transistors in the schematic) and can be aligned with the x- and y-axes of the force sensor chip 502 as described above, such that the current through the MOSFET channel flows along the <100> axis. Also, as described above, the NMOS transistors Q6, Q7 can comprise, for example, piezoelectric MOSFETs, and thus the electrical parameter responsive to the in-plane stress component induced into the deformable body 504 can comprise the current gain of the NMOS transistors Q6, Q7. In this configuration, the electronic circuit 602 can comprise input transistors Q1, Q2, Q3 and output transistors Q4, Q5. The input transistors Q1, Q2, Q3 can form a first current mirror, as shown, with the drain terminals of the Q1 and Q3 transistors coupled to a current source. Additionally, the output transistors Q4, Q5 can form a second current mirror, with the drain terminal of the transistor Q4 providing an output current I(out), as shown. The current mirror ratios of Q1-Q2, Q1-Q3, and Q4-Q5 can be independent of mechanical stress, as the directions of the drain currents of their input and output transistors are parallel to each other.

[0119] In this configuration, an input current I(in) provided by the current source is coupled to the NMOS transistor Q6, and an output current I(out) is coupled to the NMOS transistor Q7. Thus, the I(in) and I(out) currents can represent respective stress measurement signals, as discussed herein, which are also identified with their respective induced voltage signals provided to the differential amplifier 610, as shown. FIG. 6C And due to the alignment of the x- and y-axes of the force sensor chip 502 with the 1- and 2-axes in this example, an applied force generates an in-plane shear stress (sigXY) without generating in-plane normal stress components sigXX and sigYY. Thus, the stress measurement signals can represent the in-plane shear stress component sigXY, which is measured by the pair of orthogonally oriented NMOS transistors Q6, Q7. The electronic circuit 602 can also comprise a differential amplifier 610, and the stress measurement signals can be coupled to inputs of the differential amplifier 610, as shown. FIG. 6C Thus, the differential amplifier 610 outputs the in-plane shear stress sigXY as a force measurement signal in this example in response to a force applied in the normal direction of the deformable body 504 and coupled to the surface of the force sensor chip 502.

[0120] FIG. 6D Additional details are also illustrated with respect to the alignment of the stress sensor elements with the standard

[100] crystal axis of the force sensor chip 502. Although the stress sensor elements have been described above in terms of MOSFET stress sensor elements, FIG. 6B and 6C Additional details are also illustrated with respect to the orientation of the stress sensor elements as shown in FIG. 6D FIGS. 6A and 6B illustrate additional details with respect to the alignment of the stress sensor elements with the standard

[100] crystal axis of the force sensor chip 502. Although the stress sensor elements have been described above in terms of MOSFET stress sensor elements, FIG. 6B and6C The operation of the circuit shown in FIG. 6 is described above, but the stress sensor elements implemented via force sensor chip 502 are not limited to these examples. For example, force sensor chip 502 can alternatively or additionally implement resistors as stress sensor elements or as part of stress sensor elements (e.g., in combination with MOSFETs as described above). Such resistors can be formed in the same silicon on which force sensor chip 502 is fabricated, which can include implementation using any suitable technique, including known techniques. For example, stress sensor elements implemented as resistors can be formed in the silicon of force sensor chip 502 via diffusion, implantation, sputtering on top of the silicon (such as polysilicon resistors).

[0121] In any case, such resistors can also have a resistance that depends on mechanical stress, and thus can be formed on force sensor chip 502 in addition to or instead of the MOSFETs described herein to measure mechanical stress. The use of resistors as stress sensor elements is generally known, and such configurations can be combined with other components of force sensor package 500 as discussed herein to provide force measurement data. To provide an illustrative example, resistors Rl and R2 can be implemented as mechanical stress-dependent resistance stress sensor elements, and can be physically rotated 90° with respect to each other (e.g., aligned with the flow of current through the MOSFET channels of the respective Q2 and Q3 MOSFET stress sensor elements). This configuration enables amplification of the stress-dependent signals of MOSFETs Q2, Q3. Likewise, the configuration shown in FIG. 6 can be modified to replace resistors Rl and R2 with mechanical stress-dependent resistance stress sensor elements. As shown in FIG. 7, resistors Rl and R2 can be replaced with mechanical stress-dependent resistance stress sensor elements Rl'and R2', which can be physically rotated 90° with respect to each other (e.g., aligned with the flow of current through the MOSFET channels of the respective Q6 and Q7 MOSFET stress sensor elements). FIG. 6C FIG. 6C

[0122] To further explain the operation of force sensor package 500, reference is now made to FIGS. 8A and 8B, which illustrate the deformation of deformable body 504 in response to an applied force in the -z direction (i.e., in the normal direction of the surface of force sensor chip 502 as discussed above). For example, the applied force results from the compression of upper housing 510.2 in a direction toward force sensor chip 502, as shown in FIG. 8A. For the configuration shown in FIG. 8A, the applied force is transmitted to force sensor chip 502 via the upper housing 510.2 and the deformable body 504, which causes the deformable body 504 to deform in the -z direction. As a result, the deformable body 504 deforms the force sensor chip 502 in the -z direction, which causes the force sensor chip 502 to deform in the -z direction. FIG. 7 8 FIG. 7 FIG. 8B illustrates the deformation of deformable body 504 in response to an applied force in the +z direction (i.e., in the opposite direction of the normal direction of the surface of force sensor chip 502 as discussed above). For example, the applied force results from the compression of lower housing 510.1 in a direction away from force sensor chip 502, as shown in FIG. 8B. For the configuration shown in FIG. 8B, the applied force is transmitted to force sensor chip 502 via the lower housing 510.1 and the deformable body 504, which causes the deformable body 504 to deform in the +z direction. As a result, the deformable body 504 deforms the force sensor chip 502 in the +z direction, which causes the force sensor chip 502 to deform in the +z direction. FIG. 5B FIG. 7 ​​​​​For the example shown, assume that the upper housing 510.2 is displaced -30 pm in the -z direction under the action of an external force. In response, the two supports 508.1, 508.2 are pulled upwards, and the two supports 506.1, 506.2 are pushed downwards. Thus, along the direction of the 2-axis, the force sensor chip 502 surface is compressed, while the force sensor chip 502 surface is in tension in the orthogonal direction (i.e., the 1-axis). This corresponds to a difference in in-plane normal stress components: sig11 - sig22. Thus, if the force sensor chip 502 is placed as shown, then the force sensor chip 502 surface has a large shear stress sigXY, which can be on the order of -90 MPa (assuming x and y are parallel to the chip edges). FIG. 7

[0123] FIG. 8 The results of a finite element (FEM) numerical simulation are illustrated, which show that the shear stress sigXY (or normal stress difference sigXX - sigYY if the chip is rotated by 45°) is very stable. This is the case even if the applied force is not perfectly balanced between the two supports 506.1, 506.2, or when the force is not precisely in the normal direction of the surface of the force sensor chip 502.

[0124] C. Attractive force of deformable body

[0125] Likewise, it can be particularly advantageous to mechanically couple one single support of a pair of supports 506.1, 506.2, 508.1, 508.2 to its respective upper housing 510.2 or lower housing 510.1, while the other support of the pair of supports remains mechanically decoupled. To this end, it should be noted that a conventional spring for a strain gauge is a strip that is two-dimensional opposed, and thus, it is a simple process to capture the spring on one side when a force is applied to the right side, which is illustrated in the left side of FIG. 9 Thus, by mechanically coupling one of the pair of supports 506.1, 506.2, 508.1, 508.2 to its respective upper housing 510.2 or lower housing 510.1, a similar effect can be achieved. It should be noted that although one of the pair of supports 506.1, 506.2, 508.1, 508.2 can be mechanically coupled to its respective upper housing 510.2 or lower housing 510.1, there should be no gap (or minimal gap, except for manufacturing tolerances) between the deformable body 504 and the lower housing 510.1 and the upper housing 510.2.

[0126] ​In contrast, clamping each of the pairs of supports 506.1, 506.2, 508.1, 508.2 to its respective upper housing 510.2 or lower housing 510.1 would create a temperature-dependent zero-point error. For example, the lower housing 510.1 can be formed of a polymer that shrinks at a colder temperature compared to the deformable body 504. This would cause a bending of the deformable body 504 that cannot be distinguished by the electronic circuit 602 from a deflection of the deformable body 504 due to an applied force. In FIG. 10 This problem is shown in more detail in FIG. 10 Fig. 4 illustrates a deformation curve of the force sensor package 500 in this case. For FIG. 10 The illustrated curve assumes that each of the lower housing 510.1 and the upper housing 510.2 is made of a polymer with a much larger CTE than the deformable body 504. Each of the pairs of supports 506.1, 506.2, 508.1, 508.2 is glued to its respective upper housing 510.2 or lower housing 510.1 at a hotter temperature. FIG. 10 The curve in Fig. 4 shows the deformation due to the thermal shrinkage of the polymer lower housing 510.1 and upper housing 510.2 at room temperature. Thus, the lower housing 510.1 and the upper housing 510.2 shrink too much, and the shrinkage of the lower housing 510.1 creates a tensile stress on the surface of the force sensor chip 502 in the direction of the 1-axis, while the shrinkage of the upper housing 510.2 creates a compressive stress on the force sensor chip 502 in the direction of the 2-axis.

[0127] In fact, the shear stress on the surface of the force sensor chip 502 due to this thermal shrinkage looks similar to the shear stress due to an applied external force, which is shown in Fig. 5 as a hot-induced shear stress pattern (compared to the FIG. 11 FIG. 8 ​In other words, the thermal shrinkage wrinkles induce shear stresses sigXY on the surface of the force sensor chip 502, and the force sensor chip 502 cannot distinguish this thermally induced stress from the stress induced by the applied external force pushing the upper housing 510.2 downwards. Therefore, in order to avoid this thermal shrinkage problem, as described above, only one single support pair 506.1, 506.2, 508.1, 508.2 of the support pairs 506.1, 506.2, 508.1, 508.2 is clamped (e.g. mechanically coupled) to its respective upper housing 510.2 or lower housing 510.1, while the other support pair 506.1, 506.2, 508.1, 508.2 of the support pairs 506.1, 506.2, 508.1, 508.2 is free to slide laterally to prevent this thermally induced stress. Moreover, as described above, both support pairs 506.1, 506.2 can be mechanically decoupled from the upper housing 510.2, since the upper housing 510.2 in any case is pushed towards the deformation body 504 in response to the applied external force. Therefore, according to such embodiments, the upper housing 510.2 can be mechanically decoupled from the deformation body 504. Such embodiments can for example be implemented by forming the supports 506.1, 506.2 as part of the upper housing 510.2, such that the upper housing 510.2 and the supports 506.1, 506.2 form an integral component, e.g. as described above.

[0128] D. Wire bonding of sensor chip

[0129] The force sensor chip 502 can comprise any suitable electrical connections to one or more external devices, which can receive for example the force measurement signals provided by the force sensor chip 502 as described above. Therefore, the sensor elements 604 and / or the electronic circuitry 602 can do so via any suitable number of lead wires, which can be coupled to for example FIG. 6A The shown external connections, which can be coupled to the data interface 606 or form part of the data interface 606. However, such connections introduce a significant problem when the force sensor chip 502 is mounted on the deformation body 504. Therefore, due to this mounting configuration, the force sensor chip 502 also moves slightly in response to the applied external force, and thus the electrical connections between the force sensor chip 502 and any external devices need to be flexible enough to accommodate these movements, and do so in a robust and reliable manner.

[0130] Therefore, as FIG. 12 shown in one embodiment, this can be achieved using long flexible bond wires 1202. It should be noted that FIG. 12The number of bond wires shown in FIG. 12 is provided by way of example and not limitation, and force sensor package 500 can implement any suitable number and / or type of bond wires. Bond wires 1202 can be bonded to corresponding areas of force sensor chip 502 using any suitable technique. For example, external connections of force sensor chip 502 can include bond pads, bond balls, conductive traces, etc., which are then coupled to bond wires 1202 using any suitable technique, including known techniques. It should be noted that bond wires 1202 can have a suitable length so as not to compromise the reliability of the wire bonding process. Thus, the cross shape of deformable body 504 can advantageously achieve this result, as bond wires 1202 can be routed between the arms of deformable body 504 (e.g., in the slots), as shown in FIG. 12 In other words, one or more of bond wires 1202 can be coupled to force sensor chip 502 and routed between at least one pair of adjacent arms of deformable body 504.

[0131] E. Sealing of force sensor chip

[0132] Force sensor package 500 can be packaged in various ways. In one embodiment, force sensor package 502 can be of the open cavity type. For example, force sensor chip 502 and deformable body 504 can be inserted into force sensor package 500 from an opening in the top of force sensor package 500 prior to assembly of upper housing 510.2. For example, force sensor chip 502 can be bonded to deformable body 504 to form an assembly, which can then be inserted toward lower housing 510.2. Deformable body 504 can then be mechanically coupled to lower housing 510.2, for example by bonding one of support pairs 508.1, 508.2 to lower housing 510.1, as discussed herein. Alternatively, force sensor chip 502 can be bonded to deformable body 504 after deformable body 504 is mechanically coupled to lower housing 510.1.

[0133] In any case, bond wires 1202 can then be formed between force sensor chip 502 and packaged leads 1204, as shown in FIG. 12 Thus, force sensor chip 502 and deformable body 504, and lower housing 510.1 and upper housing 510.2, can be formed as an assembly, which can include optionally bonding one of support pairs 506.1, 506.2 to upper housing 510.2, as discussed herein. In FIG. 20 An example of such an alternative force sensor package 500 is shown in FIG. 20 A force sensor package 2000 is illustrated. Force sensor package 2000 can include the same components as force sensor package 500 discussed herein, with the differences between these force sensor packages being further described herein. For example, as FIG. 20As shown, the force sensor package 2000 includes a top plate 2010.2, which serves as an upper housing 510.2, as discussed herein with respect to the force sensor 500. Additionally, the force sensor package 2000 includes a substrate 2010.1, which can serve as a lower housing 510.2 as discussed herein. In any case, the top plate 2010.2 can be used to close the opening of the force sensor package 2000, thereby providing an assembled force sensor package. The top plate 2010.2 may have, for example, an outward protrusion (e.g., a rivet or boss) 2020, at which applied forces can be concentrated to a clearly defined point. The force sensor package 2000 may further include two support members 2006.1, 2006.2 and two pillar portions 2008.1, 2008.2, wherein the two support members 2006.1, 2006.2 may serve as support members 506.1, 506.2, and the two pillar portions 2008.1, 2008.2 may serve as support members 508.1, 508.2 and for applying force to the deformable body 504. The top plate 2010.2 may be non-rigidly attached to the other components of the force sensor package 2000, because the top plate 2010.2 can then transmit the applied force without loss. The top plate 2010.2 may have a snap-fit ​​mechanism as shown, which prevents the top plate 2010.2 from separating from the force sensor package 2000.

[0134] F. Additional embodiments and variations

[0135] This article is about having such FIG. 5A and 5B The use of the deformable 504 of the shape shown in the illustration is used to describe these embodiments, and the deformable 504 can be implemented to provide a single force sensor package 500. However, as discussed in further detail below, the deformable 504 and the accompanying supports 506, 508 can vary in their shape and configuration. Additionally, the force sensor package 500 may include an additional deformable 504 and a force sensor chip 502.

[0136] For example, using FIG. 5A and 5BThe deformable body 504 shown is by way of example, and the force sensor package 500 can include any suitable number of deformable bodies 504, each including a mounted force sensor chip 502 as described above. By way of illustrative example, the force sensor package 500 can include two deformable bodies 504, each having a respective force sensor chip 502 mounted thereon. The two deformable bodies 504 can be configured to act in opposite ways with respect to the in-plane stress component that arises in response to the thermal induced stress. For example, the force sensor chip of one deformable body can provide a force measurement signal that indicates an applied force that increases as temperature increases, while the force sensor chip of the other deformable body can provide a force measurement signal that indicates an applied force that decreases as temperature increases. Thus, an external device can receive these force sensor measurement signals and average them to determine the applied force. In this way, this configuration can help to compensate for errors caused by thermal induced stress. Additionally or alternatively, multiple force sensor packages can be implemented as part of a multi-sensor system to provide two different force measurement signal outputs to provide redundancy. The outputs of these force measurement signals from each force sensor chip can then be used to verify the measurement of the applied force by confirming matching measurements within a threshold tolerance, to provide a secondary measurement for safety critical applications, etc.

[0137] Likewise, the deformable body 504 can have various different shapes other than the cross shape in FIG. 5A-5B For example, the deformable body 504 can have a shape of a circle, as shown in FIG. 13A-13C Alternative shapes of the deformable body 504 are shown. For each of the alternative deformable body shapes shown, the deformable body 504 is pushed downward at the corners shown due to the interaction between the deformable body 504 and the supports 506.1, 506.2 and the upper housing 510.2 as a result of the applied force. Additionally, the deformable body is pushed upward at the corners shown due to the interaction between the deformable body 504 and the supports 508.1, 508.2 and the lower housing 510.1 as a result of the applied force. FIG. 13A-13C

[0138] FIG. 13A A deformable body 504 is shown that can have a square shape. As shown in FIG. 13A The deformable body 504 itself includes four slots extending from the center of each edge to the force sensor chip 502, as shown. Alternatively, the four slots can extend from other portions of the square perimeter, such as from the corners (not shown). FIG. 13B The deformable body 504 is shown as a square without slots. In this implementation, the deformable body 504 has increased stiffness. FIG. 13C A spiral is shown that has four arms parallel to the perimeter of the square. For each of the alternative deformable body shapes shown, the deformable body 504 is pushed downward at the corners shown due to the interaction between the deformable body 504 and the supports 506.1, 506.2 and the upper housing 510.2 as a result of the applied force. Additionally, the deformable body is pushed upward at the corners shown due to the interaction between the deformable body 504 and the supports 508.1, 508.2 and the lower housing 510.1 as a result of the applied force. FIG. 13A and 13C ​The illustrated morph, the cutout can also be used to route the bond wires, as discussed above with respect to FIG. 12 .

[0139] To provide additional examples, the morph 504 can include an H-shape, as discussed further below with respect to FIG. 14A-14C . The H-shape is topologically similar to the cross-shape, although two opposite notches are made larger, and the other two notches are absent. Thus, as compared to the 90° rotational symmetry of the cross-shape as illustrated in FIG. 5A and 5B , the H-shape includes 180° rotational symmetry. FIG. 14B FIG. 4 illustrates FEM numerical simulations of the H-shape morph 504 as illustrated in FIG. 14A , indicating the force transmitted to the H-shape morph 504 in response to an applied force in the -z direction, as discussed herein.

[0140] Additionally, it should be noted that the H-shape morph 504 includes two longitudinal edges 1402.1, 1402.2, as illustrated in FIG. 14A . In alternative embodiments, the H-shape morph 504 can be reinforced by bending it out of plane along these two longitudinal edges 1402.1, 1402.2, as illustrated in FIG. 14C . This modification makes the H-shape morph 504 less deflected for the same amount of shear stress on the force sensor chip 502.

[0141] Additionally or alternatively, the H-shape morph 504 can be further modified to adjust the implementation of any of the supports 506.1, 506.2, 508.1, 508.2. For example, continuing to refer to FIG. 14C , the support 506.2 can be replaced with a support oriented in the same way as one of the supports 508.1, 508.2 (not shown). In other words, the support 506.2 can be replaced with a separate support 508.3 placed on the opposite side of the H-shape morph 504 relative to the support 506.2, as illustrated in FIG. 14C . The H-shape morph 504 modified in this way can be mechanically coupled to the support 508.3 in any suitable way, but mechanically decoupled from the other supports 508.1, 508.2. Thus, the H-shape morph 504 can rest on the supports 508.1, 508.2 with the ability to slide laterally. In this configuration, it should be noted that an applied force in the -z direction is coupled to the H-shape morph 504 only via the support 508.3, i.e., the force is coupled to the H-shape morph 504 at a single location.

[0142] To provide additional examples, instead of supports 506.1, 506.2, 508.1, 508.2, the deformable body 504 can implement a single support 1506.1, which can be arranged relative to the deformable body 504 and the upper housing 510.2 according to any of the techniques discussed herein with respect to supports 506.1, 506.2. Thus, and as one example, the force sensor package 500 can implement a U-shaped deformable body 1502, which can include, for example FIG. 15 illustrated lead or spring lead, and can be mechanically coupled to the lower housing 510.1. The U-shaped deformable body 1502 can include two leg portions 1502.1, 1502.2, which can pass under the deformable body 504, which in this example is square, but can be any other suitable shape, while a central leg portion 1502.3 of the deformable body 1502 passes over the deformable body 504. In this implementation, either the deformable body 504 or the U-shaped deformable body 1502 can be bent out of plane.

[0143] Additionally or alternatively, and now referring to FIG. 16A-16B , the lower housing 510.1 can be implemented as any suitable type of material, such as a sheet of metal, and for example, have a protrusion (not shown) instead of any of the supports 508.1, 508.2, 508.3 as discussed herein. In this configuration, the lower housing 510.1 can be replaced with a lower housing 1610.1, as FIG. 16A-16B illustrated. The lower housing 1610.1 can include one longitudinal wall 1612, which includes a slot 1614 on one side as illustrated, into which the deformable body 504 is inserted. The slot 1614 is used to clamp the deformable body 504, and if a force presses down on the right side of the deformable body 504 at the support 1506.1, causes a resistance to movement of the deformable body 504 in the +z or -z direction.

[0144] Additionally or alternatively, instead of a protrusion in the lower housing 510.1, a cylindrical deformable body 1616 (e.g., a lead) can be implemented from one corner of the deformable body 504 to an opposite corner (e.g., along the line of the aforementioned protrusion). As FIG. 16A-16B illustrated, the cylindrical lead can be slightly bent down (e.g., 20 pm) in the center portion to avoid mechanical contact with the deformable body 504 below the force sensor chip 502.

[0145] Additionally or alternatively, instead of the cylindrical deformable body 1616 extending diagonally from one corner of the force sensor chip 502 to the opposite corner underneath the central portion of the force sensor chip 502, the deformable body 504 can rest on two balls (not shown) placed underneath these opposite corners of the deformable body 504. These balls (e.g., from a ball bearing) can be press-fit or glued into holes of the lower housing 510.1, for example, to ensure accurate positioning.

[0146] Additionally, it can be particularly advantageous to use a substrate (e.g., a printed circuit board, PCB) made of FR4 or similar material, which can include metal traces that can be in electrical contact with the force sensor chip 502. For example, instead of mounting the force sensor chip 502 directly to the deformable body 504, embodiments include assembling the force sensor chip in a package (e.g., an SMD-type package with exposed die pads and peripheral wires) and mounting the force sensor package 500 on top of the substrate. FIG. 17 An example of such an embodiment is shown in FIG. 17, which illustrates a force sensor module 1700 that can operate in a similar manner as the force sensor package 500 discussed herein. However, the force sensor module 1700 includes a substrate 1702, which in this example is a PCB. In this example, the substrate 1702 can be placed on the deformable body 504, and the force sensor package is mounted on the substrate 1702 and coupled to the deformable body 504 via the substrate 1702, as shown. Thus, in this case, the force sensor package can include the force sensor chip 502, the molding compound, and various wires, bond leads, etc., as shown and discussed further below. FIG. 17

[0147] In FIG. 17 ​In the example embodiment shown, the force sensor package can be coupled to the substrate 1702 using any suitable technique, including known techniques. For example, the force sensor package can be coupled to the substrate 1702 using an adhesive and / or solder, and inside the force sensor package, the force sensor die can be mounted face up or face down (flip chip). The top plate 1710.2 can then be mounted to the substrate 1702, which can serve the same purpose as the upper housing 510.2 discussed herein. This arrangement is particularly useful for force sensor applications that implement large full-scale forces in excess of 100 N. This is because, in this case, the primary component of the composite stiffness is defined by the deformable body 504, while the other parts of the force sensor module 1700 (e.g., the substrate 1702 and the force sensor die 502) are relatively more compliant. That is, because the substrate material and the other parts of the force sensor module 1700 have less well-defined mechanical properties (stiffness, Young’s modulus, Poisson’s number), and are more susceptible to manufacturing tolerances and environmental influences (such as temperature and humidity), the overall stiffness of the composite structure is primarily defined by the deformable body 504.

[0148] A molding compound or any other suitable technique can also be implemented to seal the force sensor die 502 and any bond wires, etc., to form the force sensor package. As shown, the force sensor package can also be sealed via use of the top plate 1710.2. Sealing the force sensor package in this way can be beneficial to protect the force sensor die 502 from dust, moisture, light exposure, mechanical failure (breakage of bond wires), etc. The mechanical coupling between the substrate 1702 and the force sensor package can be implemented, for example, any suitable bonding technique (such as an adhesive) to glue the molded force sensor package to the substrate 1702, solder one or more exposed die pads to the substrate 1702 (e.g., hard or soft soldering). This can also include, for example, soldering the bumps and balls on the bottom surface of the flip-chip of the force sensor package to the substrate 1702, and soldering the wire around the entire perimeter of the force sensor package to the substrate 1702.

[0149] Additionally or alternatively, for better mechanical coupling, more bumps, balls, and / or wires can be implemented than are needed to provide electrical connections. For example, a subset of the bumps, balls, and / or wires can provide only mechanical coupling. For example, arranging such bumps, balls, and / or wires symmetrically (e.g., over the entire contact surface of the force sensor package or along the entire perimeter) can be particularly useful to ensure isotropic strain from CTE mismatch between the force sensor package and the substrate 1702. Additionally or alternatively, embodiments include a substrate 1702 having a different lateral shape than the deformable body 504, for example, the substrate 1702 can have additional traces to route electrical traces away from the force sensor package and connect one end to a mating socket.

[0150] For example, the force sensor package can have a corresponding wire frame, e.g., as shown in FIG. 17 the two figures below. The wire frame can include a first type of wire 1720 (black) near the four corners of the force sensor package 1700, which does not cut the die paddle, and a second type of wire 1730 (gray) between the first type of wire 1720, which cuts the die paddle and is used for electrical connections to the force sensor chip 502. The first type of wire 1720 can be used to establish a better mechanical coupling between the force sensor package and the substrate 1702, e.g., near the corners of the force sensor package as shown, where large shear strain coupling. The wire frame can also be 90° rotationally symmetric so as not to break the strain pattern from the deformable body 504 onto the force sensor package, and the traces on the substrate 1702 can likewise be symmetric. This is shown in the left figure of FIG. 17 Additionally, if the force sensor chip 502 is rotated 45° with respect to the deformable body 504, the stress component is sigXX - sigYY (biaxial normal stress component). In this case, the black anchor pins of the first type of wire 1720 are also rotated, and the pins for electrical connections are also rotated. This is shown in the right figure of FIG. 17 which illustrates the use of slightly longer bond wires.

[0151] Additionally, the embodiments described herein can facilitate measuring other stress components in addition to shear stress. To do so, and to provide additional examples, the deformable body 504 can include a U-shape, as discussed further below with respect to FIG. 18-19 The force sensor chip 502 can be mechanically coupled to the center portion of the U-shaped deformable body 504 (e.g., via adhesive or other suitable bonding process as described herein, such as gluing, soldering, frit attachment with glass, etc.). As FIG. 18-19 shown, the U-shaped deformable body 504 can include two arms 504.1, 504.2, one of which (e.g., 504.2) is mechanically coupled at its distal end to the lower housing 510.1. The other arm (e.g., arm 504.1) can include a force coupling point at its distal end, which can include a protrusion as shown or any suitable standoff structure, such as any of those discussed herein. The deformable body 504 can be biased such that the mechanical coupling of arm 504.2 to the lower housing 510.1 pushes the distal end of arm 504.1 out of the plane in this way. In this way, in addition to sigXY, the applied force generates sigXX and sigYY on the force sensor chip 502 (e.g., if the x-y axes are parallel to the chip edges as described above). Thus, a force can be applied to the end of arm 504.1 of the U-shaped deformable body 504 in the -z direction.

[0152] As an illustrative example, the force sensor chip 502 can have dimensions of 1 mm x 1 mm x 0.2 mm (x-y axes parallel to the chip edges). The U-shaped deformable body 504 can be 0.4 mm thick, and the central portion of the U-shaped deformable body 504 can be 2 mm wide. The arms 504.1, 504.2 of the U-shaped deformable body 504 can be 4 mm long.

[0153] Thus, due to the applied force in the -z direction, the central portion of the U-shaped deformable body 504 is under torsion and bending action. The bending generates in-plane normal stress components (sigxx, sigyy). Also, the CTE mismatch between the U-shaped deformable body 504 material and the force sensor chip 502 generates in-plane normal stress components. In contrast, the torsion induces in-plane shear stress sigxy on the force sensor chip 502. Thus, the stress sensor elements on the force sensor chip 502 can include shear stress sensors to distinguish between force and thermal stress. Continuing the example, a force of 1 N produces a shear stress of sigxy = 55 MPa at the top and center of the force sensor chip 502. The deflection of the U-shaped deformable body 504 under the applied force is about 0.1 mm.

[0154] Thus, it can be observed that the U-shaped deformable body 504 has a rather small stiffness, regardless of its thickness (e.g., 0.4 mm). Therefore, this type of deformable body geometry is well suited for measuring small forces (1 N). An advantage of this deformable body geometry is also that the force sensor chip 502 moves very little compared to the arms of the U-shaped deformable body 504 under the applied force. This protects the dedicated bond wires that establish electrical connections between the force sensor chip 502 and the force sensor package's leads. These leads can be placed in any suitable location, such as the central portion of the U-shaped deformable body 504, fixed to the lower housing 510.1, etc. Alternatively, embodiments include attaching the leads to the central portion of the U-shaped deformable body 504 via a molded body, such as those used for conventional plastic-sealed packages. In this case, the leads should not be too short, because otherwise the leads will be slightly deformed due to the action of the applied force. FIG. 19 FEM numerical simulations of the deformations and stress components generated for this example scenario are shown.

[0155] Examples

[0156] The techniques of this disclosure can also be described in the following examples.

[0157] Example 1. A sensor package configured to be coupled to an object that is subject to mechanical deformation, the sensor package comprising: a force sensor configured to generate a force measurement signal, the force measurement signal resulting from a strain imparted to the sensor package due to an applied force causing the object to deform; a temperature sensor configured to generate a temperature measurement signal, the temperature measurement signal indicative of a temperature of a region of the sensor package proximate to the force sensor; and a processing circuitry configured to: generate temperature-corrected force measurement data based on the temperature measurement signal, the temperature-corrected force measurement data compensating for temperature errors introduced into the force measurement signal; and generate force measurement data indicative of the applied force from the temperature-corrected force measurement data.

[0158] Example 2. The sensor package of Example 1, wherein the sensor package comprises a monolithic integrated circuit (IC).

[0159] Example 3. The sensor package of any combination of Examples 1-2, wherein the force measurement signal and the temperature measurement signal are analog signals, and further comprising: an analog-to-digital converter (ADC) configured to convert the force measurement signal and the temperature measurement signal to respective digital signals, the analog-to-digital converter coupled to the processing circuitry.

[0160] Example 4. The sensor package of any combination of Examples 1-3, wherein the force sensor is mechanically coupled to the sensor package via glass frit.

[0161] Example 5. The sensor package of any combination of Examples 1-4, further comprising: a data interface coupled to the processing circuitry; and one or more bond pads coupled to the data interface and an external computing device, wherein the processing circuitry is configured to transmit the force measurement data to the external computing device via the data interface.

[0162] Example 6. The sensor package of any combination of Examples 1-5, wherein the one or more bond pads are coupled to a printed circuit board (PCB) via corresponding one or more bond balls, the PCB comprising one or more connections to the external computing device.

[0163] Example 7. The sensor package of any combination of Examples 1-6, wherein the one or more bond pads are coupled to a printed circuit board (PCB) via corresponding one or more bond leads, the PCB comprising one or more connections to the external computing device.

[0164] Example 8. The sensor package of any combination of Examples 1-7, wherein the sensor package is at least partially embedded within the PCB.

[0165] Example 9. The sensor package of any combination of examples 1-8, further comprising: a non-volatile memory configured to store electrical parameters associated with the force sensor and / or the temperature sensor, wherein the processing circuitry is configured to generate temperature-corrected force measurement data using one or more of the stored electrical parameters.

[0166] Example 10. A sensor package comprising: a deformable body; first and second supports, each of the first and second supports placed at respective locations on the deformable body opposite each other about a first line of symmetry of the deformable body; third and fourth supports, each of the third and fourth supports placed at respective locations on the deformable body opposite each other about a second line of symmetry of the deformable body, the first and second lines of symmetry being different from each other; and a force sensor chip coupled to the deformable body and configured to generate one or more measurement signals resulting from an applied force deforming the deformable body, wherein the applied force is distributed to the deformable body via the first, second, third, and fourth supports.

[0167] Example 11. The sensor package of example 10, wherein the deformable body, the force sensor chip, and the first, second, third, and fourth supports are configured to generate, in response to the applied force, normal stresses in two orthogonal directions having different values in the force sensor chip due to coupling between the force sensor chip and the deformable body.

[0168] Example 12. The sensor package of any combination of examples 10-11, wherein the force sensor chip is directly coupled to the deformable body and placed at a center of the deformable body.

[0169] Example 13. The sensor package of any combination of examples 10-12, further comprising: a printed circuit board (PCB) placed on the deformable body, wherein the force sensor chip is mounted on the PCB and coupled to the deformable body via the PCB.

[0170] Example 14. The sensor package of any combination of examples 10-13, further comprising: an upper housing placed at a first side of the deformable body; and a lower housing placed at a second side of the deformable body, the second side being opposite the first side, wherein one of the first and second supports is mechanically coupled to the upper housing, and wherein one of the third and fourth supports is mechanically coupled to the lower housing.

[0171] Example 15. The sensor package of any combination of examples 10-14, further comprising: an upper housing placed at a first side of the deformable body and mechanically decoupled from the deformable body; and a lower housing placed at a second side of the deformable body, the second side opposite the first side, wherein the first and second supports are part of the upper housing such that the upper housing forms an integral part with the first and second supports, and wherein one of the third and fourth supports is mechanically coupled to the lower housing.

[0172] Example 16. The sensor package of any combination of examples 10-15, wherein the force sensor chip comprises a pair of orthogonal metal oxide semiconductor field effect transistor (MOSFET) current mirrors or a pair of orthogonal resistors.

[0173] Example 17. The sensor package of any combination of examples 10-16, wherein the force sensor chip comprises two sensor elements, and wherein each of the two sensor elements has a respective electrical parameter that responds differently to an orthogonal in-plane stress component introduced in the deformable body due to the applied force.

[0174] Example 18. The sensor package of any combination of examples 10-17, wherein the force sensor chip comprises two sensor elements placed perpendicular to each other.

[0175] Example 19. The sensor package of any combination of examples 10-18, wherein the force sensor chip is placed on the deformable body such that the one or more measurement signals are indicative of a measurement of the in-plane stress component.

[0176] Example 20. The sensor package of any combination of examples 10-19, further comprising: an electronic circuit configured to generate a force measurement signal from the one or more measurement signals, the force measurement signal indicative of the applied force.

[0177] Example 21. The sensor package of any combination of examples 10-20, wherein the force sensor chip comprises a first and a second crystal axis from a set of <100> directions, each aligned with a first and a second symmetry line of the deformable body, respectively.

[0178] Example 22. The sensor package of any combination of examples 10-21, wherein the force sensor chip comprises a first and a second crystal axis from a set of <100> directions, each rotated by 45 degrees from a first and a second symmetry line of the deformable body, respectively.

[0179] Example 23. The sensor package of any combination of examples 10-22, wherein the deformable body comprises a planar spring having a cross shape with four arms of equal length, and wherein each of the first, second, third, and fourth supports is placed at a distal end of each respective arm of the four arms.

[0180] Example 24. The sensor package of any combination of examples 10-23, further comprising: an upper housing placed at a first side of the planar spring; a lower housing placed at a second side of the planar spring, the second side opposite the first side; and one or more bond wires coupled to the force sensor chip, wherein the one or more bond wires are routed between at least one pair of adjacent arms of the four arms of the planar spring.

[0181] Example 25. The sensor package of any combination of examples 10-24, wherein the first support, the second support, the third support, and the fourth support are part of the deformable body, such that the deformable body forms an integral component with the first support, the second support, the third support, and the fourth support.

[0182] Example 26. A sensor package comprising: a deformable body; a force sensor chip coupled to the deformable body; an electronic circuit; and at least one force coupler configured to introduce stress into the deformable body due to an applied force that deforms the deformable body, wherein the force sensor chip is configured to generate one or more measurement signals, the one or more measurement signals resulting from the stress introduced in the deformable body, and wherein the electronic circuit is configured to generate a force measurement signal from the one or more measurement signals, the force measurement signal indicative of the applied force.

[0183] Example 27. The sensor package of example 26, wherein the force sensor chip is directly coupled to the deformable body and placed at a center of the deformable body.

[0184] Example 28. The sensor package of any combination of examples 26-27, wherein the deformable body comprises a planar spring.

[0185] Example 29. The sensor package of any combination of examples 26-28, wherein the planar spring comprises a spiral, a U-shape, or an H-shape.

[0186] Example 30. The sensor package of any combination of examples 26 to 29, wherein the force sensor chip comprises a pair of orthogonal metal oxide semiconductor field effect transistors (MOSFET) current mirrors or a pair of orthogonal resistors.

[0187] CONCLUSION

[0188] While specific embodiments have been illustrated and described in this specification, it will be appreciated that any arrangement of the application described herein is made only by way of example and illustration and is not a limitation of the application. The description herein of any arrangement should therefore not be taken as limiting the scope of the application. Those skilled in the art will readily contemplate alterations and modifications of the application and embodiments thereof that are or can be suggested by the disclosure without departing from the scope and spirit of this application.

[0189] It should also be noted that specific terminology used in the specification and claims can be interpreted in a very broad sense. For example, the term "circuitry" or "circuit" used herein is interpreted to also include software, firmware, or any combination thereof in addition to hardware. The term "data" can be interpreted to include any form of representation of data. The term "information" can include other forms of representation of information in addition to any form of digital information. In embodiments, the term "entity" or "unit" can include any device, apparatus circuit, hardware, software, firmware, chip or other semiconductor, and physical implementation of logical units or protocol layers, etc. Furthermore, the term "coupled" or "connected" can be interpreted in a broad sense to include not only direct coupling but also indirect coupling.

[0190] It should also be noted that the methods disclosed in the specification or in the claims can be implemented by devices having means for performing each of the steps of these methods.

[0191] While specific embodiments are illustrated and described herein, it will be appreciated that various alternative and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This disclosure is intended to cover any and all adaptations or variations of various embodiments discussed herein.

Claims

1. A sensor package configured to couple to an object undergoing mechanical deformation, the sensor package comprising: A force sensor configured to generate a force measurement signal, the force measurement signal originating from strain transmitted to the sensor package due to deformation of the object caused by the applied force; A temperature sensor configured to generate a temperature measurement signal indicating the temperature of a region adjacent to the force sensor encapsulated in the sensor package; as well as The processing circuit device is configured as follows: Temperature-corrected force measurement data is generated based on the temperature measurement signal, and the temperature-corrected force measurement data compensates for the temperature error introduced into the force measurement signal. as well as Force measurement data indicating the applied force is generated based on the temperature-corrected force measurement data.

2. The sensor package according to claim 1, wherein the sensor package comprises a monolithic integrated circuit (IC).

3. The sensor package according to claim 1, wherein the force measurement signal and the temperature measurement signal are analog signals, and further comprising: An analog-to-digital converter (ADC) is configured to convert the force measurement signal and the temperature measurement signal into corresponding digital signals, and the ADC is coupled to the processing circuit device.

4. The sensor package of claim 1, wherein the force sensor is mechanically coupled to the sensor package via glass fusion.

5. The sensor package according to claim 1, further comprising: The data interface is coupled to the processing circuit device; as well as One or more bonding pads are coupled to the data interface and an external computing device. The processing circuitry is configured to transmit the force measurement data to the external computing device via the data interface.

6. The sensor package of claim 5, wherein the one or more bonding pads are coupled to a printed circuit board (PCB) via corresponding one or more bonding balls, the PCB including one or more connections to the external computing device.

7. The sensor package of claim 5, wherein the one or more bonding pads are coupled to a printed circuit board (PCB) via corresponding one or more bonding leads, the PCB including one or more connections to the external computing device.

8. The sensor package of claim 7, wherein the sensor package is at least partially embedded within the PCB.

9. The sensor package according to claim 1, further comprising: A non-volatile memory is configured to store electrical parameters associated with the force sensor and / or the temperature sensor. The processing circuitry is configured to use one or more of the stored electrical parameters to generate the temperature-corrected force measurement data.

10. A sensor package, comprising: Deformable body; A first support member and a second support member, each of which is placed at a corresponding position opposite to each other about a first line of symmetry of the deformable body; A third support member and a fourth support member, each of which is placed at a corresponding position opposite to each other about a second line of symmetry of the deformable body, wherein the first line of symmetry and the second line of symmetry are different from each other; as well as A force sensor chip is coupled to the deformable body and configured to generate one or more measurement signals, the one or more measurement signals originating from an applied force that causes the deformable body to deform. The applied force is distributed to the deformable body via the first support member, the second support member, the third support member, and the fourth support member.

11. The sensor package of claim 10, wherein the deformable body, the force sensor chip, and the first support, the second support, the third support, and the fourth support are configured to generate, in response to the applied force, normal stresses with different values ​​in two orthogonal directions in the force sensor chip due to the coupling between the force sensor chip and the deformable body.

12. The sensor package of claim 10, wherein the force sensor chip is directly coupled to the deformable body and is placed at the center of the deformable body.

13. The sensor package according to claim 10, further comprising: A printed circuit board (PCB) is placed on the deformed body. The force sensor chip is mounted on the PCB and coupled to the deformable body via the PCB.

14. The sensor package of claim 10, further comprising: Upper housing, the upper housing being positioned on the first side of the deformable body; as well as The lower housing is positioned on the second side of the deformable body, opposite to the first side. One of the first support member and the second support member is mechanically coupled to the upper housing, and One of the third support member and the fourth support member is mechanically coupled to the lower housing.

15. The sensor package according to claim 10, further comprising: An upper housing, which is positioned on a first side of the deformable body and is mechanically decoupled from the deformable body; as well as The lower housing is positioned on the second side of the deformable body, opposite to the first side. The first support member and the second support member are part of the upper housing, such that the upper housing and the first and second support members form a single component. One of the third support member and the fourth support member is mechanically coupled to the lower housing.

16. The sensor package of claim 10, wherein the force sensor chip comprises an orthogonal metal-oxide-semiconductor field-effect transistor (MOSFET) current mirror or a pair of orthogonal resistors.

17. The sensor package of claim 10, wherein the force sensor chip comprises two sensor elements, and in, Each of the two sensor elements has a corresponding electrical parameter that responds differently to the orthogonal in-plane stress components introduced into the deformable body due to the applied force.

18. The sensor package of claim 10, wherein the force sensor chip comprises two sensor elements placed perpendicularly to each other.

19. The sensor package of claim 10, wherein the force sensor chip is placed on the deformable body such that the one or more measurement signals indicate the measurement of in-plane stress components.

20. The sensor package of claim 10, further comprising: An electronic circuit is configured to generate a force measurement signal based on one or more measurement signals, the force measurement signal indicating the applied force.

21. The sensor package of claim 10, wherein the force sensor chip comprises components from a set of <100> The first and second crystal axes in the direction are respectively aligned with the first and second symmetry lines of the deformed body.

22. The sensor package of claim 10, wherein the force sensor chip comprises from a set of <100> The first and second crystal axes in the direction, each crystal axis is rotated 45 degrees from the first and second symmetry lines of the deformed body, respectively.

23. The sensor package of claim 10, wherein the deformable body comprises a planar spring having a cross shape, the cross shape having four arms of equal length, and Each of the first, second, third, and fourth supports is placed at the distal end of each of the four arms.

24. The sensor package according to claim 23, further comprising: Upper housing, which is placed on the first side of the planar spring; The lower housing is placed on the second side of the planar spring, the second side being opposite to the first side; as well as One or more bonding leads are coupled to the force sensor chip. The one or more connecting leads are wired between at least one pair of adjacent arms of the four arms of the planar spring.

25. The sensor package of claim 10, wherein the first support member, the second support member, the third support member, and the fourth support member are part of the deformable body, such that the deformable body and the first support member, the second support member, the third support member, and the fourth support member form an integral component.

26. A sensor package, comprising: Deformable body; A force sensor chip is coupled to the deformable body; Electronic circuits; as well as At least one force coupler is configured to introduce stress into the deformable body due to the applied force that causes the deformable body to deform. The force sensor chip is configured to generate one or more measurement signals, which originate from the stress introduced into the deformable body. The electronic circuitry is configured to generate a force measurement signal based on the one or more measurement signals, the force measurement signal indicating the applied force.

27. The sensor package of claim 26, wherein the force sensor chip is directly coupled to the deformable body and is placed at the center of the deformable body.

28. The sensor package of claim 26, wherein the deformable element comprises a planar spring.

29. The sensor package of claim 28, wherein the planar spring comprises a helical, U-shaped, or H-shaped spring.

30. The sensor package of claim 26, wherein the force sensor chip comprises an orthogonal metal-oxide-semiconductor field-effect transistor (MOSFET) current mirror or a pair of orthogonal resistors.

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