Temperature sensor assembly with circuit board

Abstract

Temperature sensor arrangement (100, 100') comprising a temperature sensor element (10), wherein the temperature sensor element (10) is arranged on a printed circuit board (11) and is electrically connected to a terminal (13) of the printed circuit board (11) via conductor tracks (14a, b), wherein the printed circuit board (11) comprises a substrate (12), wherein the substrate (12) comprises or consists of a polyimide.

Description

The invention relates to a temperature sensor arrangement and a device comprising such a temperature sensor arrangement. Temperature measurement technologies are widely used in electronic systems to monitor and control thermal conditions for optimal performance and safety. Conventional temperature sensors such as thermistors, resistance temperature detectors (RTDs), and thermocouples are typically integrated into electronic circuits to provide real-time thermal feedback. These sensors operate based on changes in electrical resistance or voltage in response to temperature fluctuations. For specialized temperature sensor applications, such as use in cryogenic environments, the sensor must fit into compact spaces and withstand harsh conditions like temperature cycling and humidity. Therefore, solutions are needed to provide reliable sensors that meet these requirements. However, materials that might be suitable for such applications may not comply with regulations, for example, per- and polyfluoroalkyl substances (PFAS), which are slated for future bans. The aim of the invention is therefore to provide a sensor for reliable and compliant temperature measurement. The object of the invention is achieved by a temperature sensor arrangement comprising a temperature sensor element, wherein the temperature sensor element is arranged on a printed circuit board and is electrically connected to a terminal of the printed circuit board via conductor tracks, wherein the printed circuit board comprises a substrate, wherein the substrate comprises or consists of a polyimide. The temperature sensor assembly is configured to enable precise temperature measurement in a variety of applications, particularly in laboratory settings and / or cryogenic environments. The temperature sensor element is positioned on the printed circuit board (PCB) to ensure secure mounting and electrical connection. The electrical connection between the temperature sensor element and the terminal is preferably established by means of at least one conductive trace formed on or within the PCB. The terminal is provided for powering the temperature sensor element and / or for transmitting measurement data from the sensor element to external devices or systems. The printed circuit board (PCB) serves as a mechanical mount and electrical interface for the temperature sensor element. The PCB includes a substrate that provides the structural basis for the assembly. The substrate is either made entirely of polyimide or incorporates polyimide as its primary material. Polyimide is chosen for its advantageous properties, including high thermal stability, chemical resistance, and mechanical flexibility. These properties make polyimide particularly suitable for use in environments where the temperature sensor assembly may be exposed to extreme temperatures or harsh conditions. The conductive traces on the PCB are configured to establish reliable electrical connections between the temperature sensor element and the terminal. These traces can be formed using conventional PCB manufacturing processes such as etching or printing and are typically made of a conductive material like copper. The connector is mounted on the circuit board and configured for connection to external wires or terminals. This allows for easy integration of the temperature sensor assembly into larger systems or devices. Preferably, the electrical connection could be achieved using contact pads. The contact pads can be etched and applied to the substrate in a suitable manner, particularly in the same way as the conductor tracks or copper conductors. The use of polyimide as a substrate material gives the temperature sensor assembly improved durability and reliability. Polyimide is advantageous due to its ability to withstand repeated temperature cycling and exposure to chemicals, which is beneficial in demanding environments such as cryogenic environments. In a preferred embodiment, the temperature sensor element is arranged on the substrate such that it is integrated into the PCB and directly connected to the PCB's conductive traces. The PCB preferably comprises only the temperature sensor as a single electrical component, with only a single circuit on the PCB connecting the temperature sensor element to the power supply and / or data exchange interface. This configuration simplifies the design and manufacturing process and reduces the installation space required for the sensor. Preferably, the printed circuit board includes exactly one or more than one, for example, two, three, four, or more, temperature sensors. Each of the additional temperature sensors can be arranged on the PCB as described with respect to the first temperature sensor. In particular, each of the sensors can be associated with further circuitry, or some or all of the sensors can be associated with the same circuitry, especially for power supply. However, each sensor can have its own data exchange line. This arrangement can facilitate assembly. Polyimide as a substrate material offers environmental and regulatory advantages. It can be used as a replacement for, or instead of, per- and polyfluoroalkyl substances (PFAS), which are increasingly subject to regulatory restrictions due to their environmental persistence and potential health risks. Many available temperature sensor assemblies contain hazardous substances that are expected to be banned in Europe in the near future. The use of polyimide addresses these concerns by providing a solution free of such substances. The approach described here aims to provide a more cost-effective and readily available alternative while maintaining the required performance standards for temperature measurement. This makes the temperature sensor array particularly suitable for widespread use in various industries striving to comply with evolving environmental and safety regulations. In one embodiment, the printed circuit board (PCB) can be flexible. This flexibility allows the temperature sensor assembly to be adapted to various installation environments and geometries. The PCB can be designed to be bent or folded without compromising the integrity of the electrical connections between the temperature sensor element and the terminal. Such a flexible configuration can be achieved by selecting suitable materials and manufacturing processes that maintain the electrical and mechanical performance of the assembly while allowing for deformation. Depending on the requirements of the intended application, the flexible printed circuit board (PCB) can be either elastic or non-elastic. The PCB is specifically either dynamic or static. The elastic property refers in particular to the ability of the flexible PCB to be bent elastically. Specifically, the flexible PCB is not capable of expanding and contracting. In certain embodiments, the flexibility may be sufficient to allow the temperature sensor assembly to adapt to curved or irregular surfaces, thus facilitating installation in confined or complex spaces. Furthermore, depending on the specific requirements of the application, the flexible or bendable printed circuit board can be designed to be either elastic or non-elastic. The flexibility can be adjusted to allow either temporary deformation (elastic) or permanent shaping (non-elastic), depending on the installation needs. Furthermore, the choice of polyimide as the substrate material is particularly compatible with flexible printed circuit board (PCB) designs. Polyimide offers excellent thermal stability, moisture resistance, and mechanical flexibility, making it especially suitable for use in demanding environments, including cryogenic conditions. This material selection ensures that the flexible PCB retains its durability and performance even under extreme temperature fluctuations. In another embodiment, the temperature sensor element can be configured for measuring temperatures of -200 °C, preferably -150 °C, and even more preferably -100 °C and higher. The temperature sensor element can be selected or designed to operate reliably at very low temperatures, enabling accurate measurement in cryogenic or sub-zero environments. Such a configuration can be particularly advantageous in applications requiring the monitoring of extremely low temperatures, for example, in scientific research, industrial processes, or cryogenic storage systems. The temperature sensor arrangement can be configured to meet specific requirements for accurate measurement at temperatures down to, for example, -90 °C. It is also possible for the sensor to take the form of a layer bonded to the substrate. The layer would be bonded to the substrate in the same way as the copper conductors. The material of the sensor or the layer is preferably platinum or another suitable material. In another possible embodiment, the temperature sensor element can be a PT1000 or PT100 sensor. Alternatively, other suitable sensors can be used. The PT1000 or PT100 sensor is a type of resistance temperature detector (RTD) characterized by a nominal resistance of 1000 or 100 ohms at 0 °C. Using a PT1000 or PT100 sensor can provide high accuracy and stability in temperature measurement, especially at low temperatures. The PT1000 or PT100 sensor element can be mounted on the circuit board and electrically connected to the terminal via the traces, as previously described. The PT1000 or PT100 sensor can be selected based on its advantageous characteristics, including a predictable and nearly linear resistance-temperature ratio, which enables precise temperature monitoring over a wide temperature range. The PT1000 or PT100 sensor element can be designed in various forms, such as thin-film or wire-wound constructions, depending on the specific requirements of the application. In another embodiment, the printed circuit board (PCB) can have an elongated shape. This elongated configuration can be implemented such that the length of the PCB is significantly greater than its width. This form factor can be chosen to facilitate installation in narrow or confined spaces, or to allow the temperature sensors to be positioned along surfaces or within enclosures where space is limited. The elongated shape can also facilitate the placement of the temperature sensor element in close proximity to the area being monitored, thereby improving the responsiveness and accuracy of the temperature monitoring. The elongated shape can also support the arrangement of the temperature sensor element at a specific point along the length of the circuit board, enabling targeted temperature measurement at a desired point within the application environment. In particular, the elongated circuit board can be designed to optimize the routing of the conductor tracks between the temperature sensor element and the connection. Furthermore, the elongated circuit board can be implemented with a single temperature sensor element arranged along its length. This approach can simplify the design and reduce the overall area of ​​the temperature sensor array, making it particularly suitable for applications where space saving is a priority. In another possible embodiment, the connector can be located at a first end section of the printed circuit board (PCB), and the temperature sensor can be located at a second end section of the PCB. Positioning the connector at one end section and the temperature sensor at the opposite end section allows for a straightforward electrical connection and efficient spatial separation between the connection interface and the measurement point. This configuration can be particularly advantageous in applications where it is desirable to position the temperature sensor element at a specific location within a device or system, while simultaneously ensuring convenient access to the connector for integration with external wiring or electronics.This can be advantageous in scenarios where the measurement point is physically far from the available connection point, or where the sensor array needs to bridge a gap between two locations within the application environment. In particular, the conductive traces can extend the length of the circuit board and electrically connect the terminal at the first end section to the temperature sensor at the second end section. This arrangement can help minimize the overall area of ​​the temperature sensor assembly and facilitate easy installation in confined or elongated spaces. Furthermore, separating the terminal and the temperature sensor element at opposite end sections can reduce the risk of thermal interference from the terminal or associated electronics, thereby enabling more accurate temperature measurement at the desired location. In another embodiment, the length of the printed circuit board (PCB) can be between 100 mm and 300 mm. In some embodiments, the length can preferably be selected within a range of 150 mm to 250 mm. In a particularly preferred configuration, the length can even more preferably be between 180 mm and 220 mm. The specific length of the PCB can be selected according to the requirements of the intended application and the available installation space. By selecting a suitable length within these ranges, it is possible to optimize the arrangement with regard to both ease of installation and reliable operation. The elongated PCB, whose length optionally falls within the aforementioned ranges, can facilitate the placement of the temperature sensor element at a desired measuring point and simultaneously allow for convenient positioning of the connection for integration into external systems. It should be noted that the space-saving design made possible by the specified dimensions is particularly advantageous for laboratory applications. For example, laboratory equipment such as centrifuges often offers limited installation space and requires compact sensor solutions. The ability to provide a temperature sensor assembly with a circuit board length between 100 mm and 300 mm, and preferably within the narrower ranges described above, can facilitate efficient integration into such laboratory equipment. Alternative embodiments can also be considered for other laboratory equipment or compact systems with similar spatial and functional requirements. In another possible embodiment, the width of a first end section of the printed circuit board (PCB), where the connector can be located, can be greater than the width of a middle section and / or a second end section of the PCB. This configuration can offer advantages in terms of mechanical stability and ease of handling, particularly at the point where the connector is mounted. The increased width at the first end section can facilitate secure mounting of the connector and allow the use of larger or more robust connector types, if required by the application. Optionally, the middle section and / or the second end section of the printed circuit board (PCB), where the temperature sensor element can be located, can have a reduced width compared to the first end section. This reduction in width can contribute to a more compact and space-saving design, allowing the temperature sensor assembly to be installed in environments where space is limited. The narrower middle and / or second end section can also reduce overall material consumption and the weight of the PCB, which can be advantageous in applications where minimizing mass is important. The transition between the wider first end section and the narrower middle and / or second end section can be designed as a step, taper, or other suitable geometric transition. It can be advantageous if the width of the second end section, where the temperature sensor element is located, is identical to the width of the middle section. In such an arrangement, the circuit board can consist of a first strip-shaped section with a constant width, where the sensor is located at the first end, and a second section with a wider, constant width, where the connector is located. In another possible embodiment, the width of the first end section of the circuit board, where the connection can be located, can be selected to be between 3 mm and 8 mm. In some embodiments, the width of the first end section can preferably be in the range of 4 mm to 6 mm. In a particularly preferred configuration, the width of the first end section can even more preferably be between 4.5 mm and 5.5 mm. Additionally or alternatively, the width of the second end section, where the temperature sensor element can be located, can be between 8 mm and 16 mm. In certain embodiments, the width of the second end section can preferably be in the range of 10 mm to 14 mm, and in a even more preferred arrangement, between 11 mm and 13 mm. The selection of these width ranges for the first and second end sections can be made according to the requirements of the intended application and the available installation space. The specified dimensions can be particularly advantageous in laboratory or industrial applications, where compact sensor solutions are often required. In another possible embodiment, the width of the second end section can be between 30% and 50% of the width of the first end section. In certain configurations, the width of the second end section can preferably be selected in the range of 40% to 45% of the width of the first end section. In a particularly preferred arrangement, the width of the second end section can preferably be between 42% and 45% of the width of the first end section. This proportional ratio between the widths of the end sections can be selected to optimize the mechanical and spatial properties of the temperature sensor arrangement for specific installation requirements. Selecting the width of the second end section as a percentage of the width of the first end section can offer advantages in terms of compactness and adaptability.This proportional width configuration is particularly well-suited for specific applications in laboratory devices where installation space is often limited and compact sensor arrangements are desirable. However, it is also possible to implement the temperature sensor arrangement with alternative dimensions, depending on the requirements of other applications or devices. Preferably, the temperature sensor can comprise one or more mounting sections for securing the temperature sensor within a device. For example, one or more mounting tabs with a mounting opening can be provided, which are particularly integrated into or integrally formed with the PCB or the PCB substrate. The mounting sections are preferably provided in the first end section. For example, the mounting sections can be provided as a section with a greater width compared to the rest of the first end section, which is designed to include one or two mounting sections. The width of such a mounting section can be between 20 mm and 50 mm, preferably between 25 mm and 34 mm, and even more preferably between 30 mm and 35 mm. Further mounting openings can be provided on the PCB or the PCB substrate. Preferably, the width of the first end section can be between 3% and 15%, preferably between 5% and 13%, even more preferably between 8% and 10% of the length of the PCB. Preferably, the width of the second end section can be between 2% and 10%, more preferably between 2.5% and 7%, and even more preferably between 3% and 5% of the length of the PCB. In another possible embodiment, the thickness of the printed circuit board (PCB) can be selected to be between 10 µm and 350 µm. In some configurations, the thickness can preferably be in the range of 35 µm to 300 µm. In a particularly preferred arrangement, the thickness can even more preferably be between 100 µm and 150 µm. For example, the thickness can be 125 µm. A local thickness can be less than 1 mm, for example, 0.95 mm. This local thickness can be greater at both ends of the PCB. The specific thickness of the PCB can be selected according to the mechanical, electrical, and installation-related requirements of the intended application. Selecting a suitable thickness can strike a balance between mechanical stability, flexibility, and ease of handling, while ensuring reliable electrical performance.The thickness of the printed circuit board (PCB) can be adjusted to ensure sufficient rigidity for supporting the temperature sensor element and connector, while simultaneously allowing for any desired degree of flexibility, particularly in applications where the PCB needs to be bent or conform to specific installation geometries. A thinner PCB can offer increased flexibility and reduced weight, which can be advantageous in compact or space-constrained environments. Conversely, a thicker PCB can provide improved mechanical robustness and resistance to damage from handling or vibration. Preferably, the printed circuit board can be manufactured with a constant thickness along its entire length. In another embodiment, the connection can be implemented as a plug connector. Using a plug connector can provide a convenient and reliable way to electrically connect the temperature sensor assembly to external devices or systems. The plug connector can be a socket of any suitable type, such as a pin header, a plug socket, or a modular connector, and can be selected according to the requirements of the intended application and compatibility with existing connection standards. The plug connector can be mounted at an end section of the printed circuit board, allowing for easy connection and disconnection without special tools. Using a plug connector can simplify the process of making electrical connections by eliminating the need for soldering or manual connection.This design consideration can reduce installation time, minimize the risk of connection errors, and support efficient use in both new and retrofit applications. Preferably, the connector can be designed to support repeated mating cycles, thereby ensuring durability and long-term reliability in applications where the temperature sensor assembly may be installed, removed, or replaced multiple times. Preferably, the connector can be compatible with standard connector types used in industrial or laboratory equipment, thus enabling the temperature sensor assembly to be easily integrated into a wide variety of systems. In another possible embodiment, the connection can be a pin connector, in particular a two-, three-, or four-pin connector. The use of a pin connector can provide a simple and compact electrical interface between the temperature sensor assembly and external devices or systems. The pin connector can, for example, comprise two pins for mating with a corresponding connector. The pin connector can be mounted at an end section of the printed circuit board and can be configured to provide a reliable electrical contact for both powering the temperature sensor element and transmitting measurement signals. In some embodiments, the two-pole connector can be oriented so that, depending on the spatial limitations and integration requirements of the device or system, it can be connected either vertically or horizontally to a suitable socket or receptacle. The pin connection can be implemented in various standardized formats, such as pin headers, terminal blocks or connectors, depending on the specific requirements of the application. The object of the invention is further achieved by a device comprising a temperature sensor arrangement according to one of the embodiments described above. The device includes a temperature sensor arrangement comprising a temperature sensor element mounted on a printed circuit board, the printed circuit board comprising a substrate that includes or consists of a polyimide. The temperature sensor element is electrically connected to a terminal of the printed circuit board via conductive traces. The temperature sensor assembly can be integrated into the device such that the temperature sensor element is positioned at a measuring area within the device where the temperature is to be monitored. This measuring area can be a specific region or component of the device where precise temperature control or monitoring is required. The connection for the temperature sensor assembly is preferably located at a point that is easily accessible for maintenance purposes. In another embodiment, the device can be a laboratory device. The device can optionally be configured for use in laboratory environments where precise and reliable temperature measurement is frequently required. For example, the laboratory device can optionally be a centrifuge. In such a configuration, the temperature sensor array can be installed inside the centrifuge housing or rotor chamber to monitor the temperature of samples during operation. Alternative laboratory devices, such as incubators, freezers, or analytical instruments, can also incorporate the described temperature sensor array, depending on the specific application requirements. The invention is explained in more detail below with reference to exemplary embodiments. Figure 1 schematically shows a top view of a temperature sensor arrangement according to a first embodiment, and Figure 2 shows a top view of a temperature sensor arrangement according to a second embodiment. Fig. 1 shows a temperature sensor arrangement 100 comprising an elongated, flexible printed circuit board 11 formed from and encompassing a polyimide substrate 12, wherein the printed circuit board 11 carries a temperature sensor element 10 at a narrowed second end section 15b and a connector 13 at a widened first end section 15a. The printed circuit board 11 has a total length L of 193 mm, with the elongated central section 15c extending from the second end section 15b, which has a width of 5 mm, and from the widened first end section 15a, which has a width of 12 mm. Two parallel conductor tracks 14a, b run along the length L of the printed circuit board from the temperature sensor element 10 at the second end section 15b to corresponding contacts of the connector 13 at the first end section 15a, providing an electrical connection between the temperature sensor element 10 and the connector 13. The temperature sensor element 10 is designed as a PT1000 and is configured for temperature measurements down to at least -100 °C and beyond, with the flexible polyimide substrate 12 enabling placement and bending in confined spaces without affecting the integrity of the conductor tracks 14a, b or the connection to the connector 13. Fig. 2 shows a temperature sensor arrangement 100' according to a further embodiment. The embodiment shown here differs from that shown in Fig. 1 in that the first end section 15a comprises a mounting section with two mounting tabs 16 extending from two sides of the first end section 15a. The fastening section has a width W3, which can be 33 mm. Furthermore, the first end section 15a includes fastening holes arranged on the fastening tabs 16 in the fastening section, as well as a third fastening hole positioned centrally on the first end section 15a. List of reference symbols 100, 100' Temperature sensor assembly 10 Temperature sensor element 11 Printed circuit board 12 Substrate 13 Connection 14a, b Conductive traces 15a First end section 15b Second end section 15c Middle section 16 Mounting tabs L Length of printed circuit board W1 Width of first end section W2 Width of second end section W3 Width of mounting section

Claims

Temperature sensor arrangement (100, 100') comprising a temperature sensor element (10), wherein the temperature sensor element (10) is arranged on a printed circuit board (11) and is electrically connected to a terminal (13) of the printed circuit board (11) via conductor tracks (14a, b), wherein the printed circuit board (11) comprises a substrate (12), wherein the substrate (12) comprises or consists of a polyimide. Temperature sensor arrangement (100, 100') according to claim 1 , wherein the circuit board (11) is flexible. Temperature sensor arrangement (100, 100') according to one of the preceding claims, wherein the temperature sensor element (10) is configured for temperature measurement of temperatures of -200 °C, preferably -150 °C, more preferably -100 °C, and higher. Temperature sensor arrangement (100, 100') according to claim 3, wherein the temperature sensor element (10) is a PT1000 or a PT100 sensor. Temperature sensor arrangement (100, 100') according to one of the preceding claims, wherein the circuit board (11) has an elongated shape. Temperature sensor arrangement (100, 100') according to claim 5, wherein the connection (13) is arranged at a first end section (15a) of the circuit board (11) and the temperature sensor (10) is arranged at a second end section (15b) of the circuit board (11). Temperature sensor arrangement (100, 100') according to claim 5 or 6, wherein the length (L) of the circuit board is between 100 mm and 300 mm, preferably between 150 mm and 250 mm, more preferably between 180 mm and 220 mm. Temperature sensor arrangement (100, 100') according to one of claims 5 to 7, wherein the width of a first end section (W1) having the connection (13) is greater than the width of a middle section (15c) and / or a second end section (15b). Temperature sensor arrangement (100, 100') according to claim 8, wherein the width of the first end section (W1) is between 3 mm and 8 mm, preferably between 4 mm and 6 mm, more preferably between 4.5 mm and 5.5 mm, and / or wherein the width of the second end section (W2) is between 8 mm and 16 mm, preferably between 10 mm and 14 mm, more preferably between 11 mm and 13 mm. Temperature sensor arrangement (100, 100') according to claim 6 and one of claims 7 to 9, wherein the width of the second end section (W2) is between 30% and 50%, preferably between 40% and 45%, more preferably between 42% and 45% of the width of the first end section (W1). Temperature sensor arrangement (100, 100') according to one of the preceding claims, wherein the thickness of the circuit board (11) is between 10 µm and 350 µm, preferably between 35 µm and 300 µm, more preferably between 100 µm and 150 µm. Temperature sensor arrangement (100, 100') according to one of the preceding claims, wherein the connection (13) is a connector. Temperature sensor arrangement (100, 100') according to claim 12, wherein the connection (13) is a pin connection, in particular a two-, three- or four-pin connection. Device comprising a temperature sensor arrangement (100, 100') according to any one of claims 1 to 13. Device according to claim 14, wherein the device is a laboratory device.

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