Precision measurement circuit protection method and device

Abstract

The invention discloses a precision measurement circuit protection method and device, and the method comprises the following steps: providing an electromagnetic shielding housing which is provided with an accommodation cavity for accommodating a precision measurement circuit; a phase-change material layer is arranged on the inner wall of the accommodating cavity, and the phase-change temperature of the phase-change material is in a normal working temperature interval of the precision measurement circuit; the precision measurement circuit is arranged in the accommodating cavity and is connected with a uniform temperature plate through a heat-conducting medium layer, so that heat generated by the precision measurement circuit can be transmitted to the uniform temperature plate through the heat-conducting medium layer; a temperature detection control unit is arranged and used for detecting the temperature of the vapor chamber in real time; and when the temperature of the uniform temperature plate exceeds a preset threshold value, a temperature control execution mechanism is started to carry out active temperature adjustment on the uniform temperature plate.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit protection technology, and specifically to a method and apparatus for protecting precision measurement circuits. Background Technology

[0002] Precision measurement circuits on circuit boards (such as high-precision ADCs, reference voltage sources, and sensor signal conditioning circuits) have extremely high requirements for the operating environment during power-on. However, factors such as device self-heating, ambient temperature changes, and environmental electromagnetic interference can disrupt the ideal operating environment of the circuit at any time. These interferences can cause input / output signal drift and a decrease in signal-to-noise ratio, or even permanently damage circuit components, resulting in serious economic and research losses.

[0003] Existing protection methods for precision measurement circuits have significant shortcomings. Some methods focus on electromagnetic shielding, employing structures such as metal shielding covers, which can effectively suppress electromagnetic interference, but completely neglect temperature management of the circuit. Especially in confined spaces, the temperature rise caused by chip heating may actually be exacerbated. Other methods attempt to address both electromagnetic interference and temperature control simultaneously, but their structures are often bulky, have low temperature control efficiency, and exhibit response delays. They cannot adjust the temperature of core components in precision measurement circuits in a timely and rapid manner, making it difficult to meet the real-time requirements of high-precision measurements.

[0004] Therefore, there is an urgent need in this field for a precision measurement circuit protection solution that can integrate efficient electromagnetic shielding and rapid active temperature control, and is compact and responsive. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method and apparatus for protecting precision measurement circuits. This method and apparatus not only effectively shield against external electromagnetic interference, but also quickly detect and control the operating temperature of the circuit, ensuring that the precision measurement circuit always operates in a relatively electromagnetically pure and temperature-constant stable environment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for protecting a precision measurement circuit includes the following steps: An electromagnetic shielding enclosure is provided, the enclosure having a receiving cavity for accommodating precision measurement circuitry; A phase change material layer is provided on the inner wall of the accommodating cavity, and the phase change temperature of the phase change material is within the normal operating temperature range of the precision measurement circuit. The precision measurement circuit is placed inside the cavity and connected to a heat spreader plate through a thermally conductive medium layer, so that the heat generated by the precision measurement circuit can be transferred to the heat spreader plate through the thermally conductive medium layer. A temperature detection and control unit is set up to detect the temperature of the heat exchange plate in real time; When the temperature of the heat exchanger exceeds a preset threshold, a temperature control actuator is activated to actively adjust the temperature of the heat exchanger.

[0007] To achieve optimal broadband electromagnetic shielding while minimizing device size, in one alternative embodiment, the electromagnetic shielding shell is a multilayer composite material housing customized to the dimensions of the precision measurement circuit, incorporating both reflection and absorption losses. By combining reflection and absorption losses, the multilayer composite material can reduce electromagnetic interference by more than 40 dB and offers a wider effective bandwidth and better suppression than a single metallic shielding layer.

[0008] In order to make the same protection method flexibly applicable to various precision measurement circuits with different optimal operating temperature ranges, in one optional embodiment, the phase transition temperature is adjusted by adding dopants to the phase transition material to adapt it to the operating temperature range of different precision measurement circuits.

[0009] To address the issues of poor contact and varying thermal conductivity caused by different chip heights, in one optional embodiment, the thermally conductive medium layer is an insulating thermally conductive material. By controlling its coating thickness, multiple chips of different heights on the precision measurement circuit can achieve uniform planar contact with the heat spreader.

[0010] In order to ensure the electrical insulation safety of the circuit while guaranteeing extremely high thermal conductivity, in one optional embodiment, the insulating thermally conductive material is ceramic-based thermally conductive silicone grease.

[0011] To achieve rapid, accurate, and reversible active temperature control, in one optional embodiment, the temperature control actuator includes a thermoelectric cooler and a heat sink; when cooling is required, the thermoelectric cooler is activated, its cold end is attached to the vapor chamber, and the heat generated by its hot end is dissipated through the heat sink.

[0012] To ensure the stability of the connection between the protective device and the circuit board and the continuity of electromagnetic shielding, an edge mounting structure is provided. In an optional embodiment, the electromagnetic shielding shell is fixed to the circuit board by the mounting structure provided at its edge.

[0013] This embodiment also provides a precision measurement circuit protection device for implementing any of the methods described above, the device comprising: The electromagnetic shielding shell has an internal cavity for accommodating precision measurement circuits; A phase change material layer is attached to the inner wall of the accommodating cavity; A temperature distribution plate is disposed within the accommodating cavity; A thermally conductive medium layer is used to establish the connection between the precision measurement circuit and the heat spreader. Temperature detection and control unit, disposed on the heat spreader plate; and The temperature control actuator is connected to the temperature detection and control unit and actively adjusts the temperature of the heat exchange plate in a controlled manner.

[0014] In one optional embodiment, the temperature control actuator is a semiconductor refrigeration chip, with its cold end connected to the heat spreader and its hot end connected to a heat sink.

[0015] In one optional embodiment, the electromagnetic shielding shell is a detachable structure with an opening on one side, and is mounted on a circuit board through a screw hole structure at the edge of the opening.

[0016] The beneficial effects that the precision measurement circuit protection method and device disclosed in this application may bring include, but are not limited to: 1. High integration and comprehensive protection: Electromagnetic shielding, passive temperature control and active temperature control are integrated into a compact device, which solves the two major problems of electromagnetic interference and temperature fluctuation at the same time.

[0017] 2. Fast response and precise temperature control: Through rapid heat conduction between the heat-conducting medium and the heat spreader, combined with a high-response semiconductor cooling chip and real-time temperature feedback, the circuit temperature can be quickly and accurately adjusted.

[0018] 3. Strong thermal balance capability: The heat spreader eliminates the temperature gradient between multiple chips, the phase change material smooths out the drastic changes in ambient temperature, and the active temperature control handles the continuous heat load. The three work together to achieve dynamic thermal balance.

[0019] 4. High versatility and wide applicability: By customizing the shell size and adjusting the phase change material formula, this method and device can be flexibly adapted to precision measurement circuits of various sizes and with different operating temperature requirements. Attached Figure Description

[0020] Figure 1 This is a cross-sectional structural diagram of the protective device of the present invention.

[0021] Figure 2 This is a three-dimensional schematic diagram of the protective device of the present invention.

[0022] Illustration: 1-Outer shell, 2-Semiconductor cooling chip, 3-Heat sink, 4-Temperature detection and control unit, 5-Phase change material layer, 6-Heat conduction medium layer, 7-Precision measurement circuit, 8-Population plate. Detailed Implementation

[0023] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] like Figures 1 to 2 As shown, a method for protecting a precision measurement circuit includes the following steps: An electromagnetic shielding housing 1 is provided, the housing 1 having a accommodating cavity for accommodating a precision measuring circuit 7; A phase change material layer 5 is provided on the inner wall of the accommodating cavity, and the phase change temperature of the phase change material is within the normal operating temperature range of the precision measurement circuit 7. The precision measurement circuit 7 is placed inside the cavity and connected to a heat spreader 8 through a thermally conductive medium layer 6, so that the heat generated by the precision measurement circuit 7 can be transferred to the heat spreader 8 through the thermally conductive medium layer 6. A temperature detection and control unit 4 is set up to detect the temperature of the heat exchange plate 8 in real time; When the temperature of the heat exchanger 8 exceeds the preset threshold, a temperature control actuator is activated to actively adjust the temperature of the heat exchanger 8.

[0026] To address the two core issues of electromagnetic interference and temperature fluctuations, and to achieve rapid response, this solution organically combines four technical approaches: electromagnetic shielding, passive phase-change temperature control, active temperature equalization, and feedback control. The electromagnetic shielding shell 1 solves the problem of external electromagnetic interference; the phase-change material layer 5 provides a passive buffer against drastic changes in ambient temperature, increasing the system's thermal inertia; the combination of the temperature equalization plate 8 and the thermally conductive medium layer 6 solves the problem of temperature imbalance among multiple chips and provides a unified and efficient thermal interface for temperature detection and control; finally, the temperature detection and active control stage accurately and quickly responds to the circuit's own heating or continuous external temperature changes, achieving dynamic thermal balance.

[0027] Specifically, firstly, an electromagnetic shielding shell 1 is used to construct a physical barrier, isolating the precision measurement circuit 7 from the external electromagnetic environment. Secondly, a phase change material layer 5 is placed on the inner wall of the shell 1 as the first passive temperature buffer. When the ambient temperature changes abruptly, the phase change material absorbs or releases a large amount of latent heat through solid-liquid phase change, delaying the temperature change inside the shell. Then, through the thermally conductive medium layer 6 and the heat spreader 8, the heat from multiple chips on the circuit board that may have uneven heating is quickly conducted and balanced, forming a unified temperature monitoring plane. The temperature detection and control unit 4 monitors the temperature of this plane in real time. Once its temperature exceeds the preset safe operating threshold (e.g., upper limit 35°C, lower limit 15°C), the temperature control actuator (such as a cooling or heating device) is immediately activated to actively and precisely adjust the temperature of the heat spreader 8, thereby quickly pulling the circuit temperature back to the safe range.

[0028] To achieve optimal broadband electromagnetic shielding while minimizing device size, in one alternative embodiment, the electromagnetic shielding housing 1 is a shell made of a multi-layered composite material that combines reflection and absorption losses, custom-designed to fit the dimensions of the precision measurement circuit 7. By combining reflection and absorption losses, the multi-layered composite material can reduce electromagnetic interference by more than 40 dB and offers a wider effective bandwidth and better suppression than a single metal shielding layer.

[0029] It should be noted that the outer casing 1 is not a standard part, but a custom design based on the actual size and layout of the precision measurement circuit board 7 to be protected, in order to achieve a minimal volume footprint. Its material is a multi-layered composite material, consisting of, from the outside in, a conductive metal layer, a magnetic material layer, and an inner insulating protective layer. This structure enables wide-bandgap electromagnetic shielding (e.g., from MHz to GHz).

[0030] The conductive metal layer, such as copper foil or aluminum foil, is used to shield high-frequency electromagnetic waves through reflection; the magnetic material layer, such as ferrite coating or nanocrystalline ribbon, is used to absorb low-frequency electromagnetic waves through magnetic loss.

[0031] Optionally, the specific composition of the multilayer composite material can be changed. For example, the conductive layer can be made of conductive cloth or metal plating, and the absorbing layer can be made of carbon-based absorbing material.

[0032] To enable the same protection method to be flexibly applied to various precision measurement circuits 7 with different optimal operating temperature ranges, in one optional embodiment, the phase transition temperature of the phase change material is adjusted by adding dopants, thus adapting it to the different operating temperature ranges of the precision measurement circuits 7. This greatly enhances the versatility of the invention, eliminating the need to develop a dedicated phase change material for each circuit at a specific temperature; only formula adjustments to the base material are required.

[0033] Specifically, phase change materials can be paraffin wax, hydrated salts, fatty acids, etc. Their inherent phase change temperature may not meet the requirements of a specific circuit (e.g., a circuit requires an operating temperature of 25℃±5℃, while the phase change point of pure paraffin wax is 28℃). In this case, by adding dopants, such as nano-metal oxides (alumina, copper oxide), carbon nanotubes, or different types of salts, their crystal structure or intermolecular forces can be altered, thereby precisely raising or lowering their phase change temperature.

[0034] Of course, in addition to adding dopants, the desired phase transition temperature can also be obtained directly by selecting paraffin mixtures with different chain lengths or different types of hydrated salts.

[0035] To address the issues of poor contact and varying heat conduction efficiency caused by the different heights of multiple chips, in one optional embodiment, the thermally conductive medium layer 6 is an insulating and thermally conductive material. By controlling its coating thickness, multiple chips of different heights on the precision measurement circuit 7 can achieve uniform planar contact with the heat spreader 8. This technical solution ensures that an efficient and uniform thermal path can be established between the heat spreader 8 and all heat sources, avoiding the generation of localized hot spots and truly achieving the "uniform temperature" effect of the heat spreader 8.

[0036] Chip packages on circuit boards often have inconsistent heights. This invention uses insulating and thermally conductive materials with fluidity and compressibility, such as thermal grease and thermal pads. During installation, a thinner layer is applied to higher chips, and a thicker layer is applied to lower chips or blank areas on the PCB, ultimately ensuring that the upper surfaces of all thermally conductive media layers 6 in contact with the heat spreader 8 are at the same horizontal level. When the heat spreader 8 is pressed together, the contact pressure and thermal resistance at each point tend to be uniform.

[0037] To ensure both extremely high thermal conductivity and electrical insulation safety of the circuit, in one optional embodiment, the insulating thermally conductive material is ceramic-based thermal grease. Ceramic-based thermal grease is a high-performance thermal paste with silicone oil as the base oil and ceramic micropowders such as alumina and boron nitride as fillers. It fills the microscopic gaps between the chip and the vapor chamber 8, expelling air and significantly reducing contact thermal resistance. The ceramic filler itself is an excellent thermal conductor and electrical insulator, giving it both a high heat dissipation coefficient and excellent insulation, preventing the risk of chip short circuits.

[0038] In order to achieve fast, accurate and reversible active temperature control, in one optional embodiment, the temperature control actuator includes a thermoelectric cooler 2 and a heat sink 3; when cooling is required, the thermoelectric cooler 2 is activated, its cold end is attached to the heat spreader 8, and the heat generated by its hot end is dissipated through the heat sink 3.

[0039] The semiconductor cooling chip 2 is based on the Peltier effect, cooling one end and heating the other when energized. In this invention, its cold end is tightly attached to the heat spreader 8 using thermal paste, acting as a "heat pump" to draw heat away from the heat spreader 8. The heat generated at its hot end is then dissipated to the outside of the device or a larger system environment through a finned heat sink 3 via convection and radiation.

[0040] This solution boasts a fast response time and high reliability, capable of both cooling and heating via reverse current, making it ideal for precision temperature control applications. Heat sink 3 ensures that heat from the hot end of the cooling element is promptly dissipated, maintaining its operational efficiency.

[0041] To ensure the stability of the connection between the protective device and the circuit board and the continuity of electromagnetic shielding, an edge mounting structure is provided. In an optional embodiment, the electromagnetic shielding housing 1 is fixed to the circuit board by the mounting structure provided at its edge. This installation method is simple and reliable, ensuring good electrical contact between the housing 1 and the ground plane of the circuit board, and ensuring the lower limit integrity of the electromagnetic shielding effectiveness.

[0042] Specifically, the mounting structure can be screw holes, clips, or guide pins. For example, screw holes can be provided at the four corners of the opening edge of the housing 1, and screws can be used to directly lock it into the pre-set threaded holes on the circuit board or to fix it through a support, forming a sealed protective cavity.

[0043] It should be noted that the mounting structure can be a spring pin contact array for crimping, or it can be bonded with conductive adhesive.

[0044] like Figure 1-2 As shown, this embodiment also provides a protection device for a precision measurement circuit 7, and a method for implementing it. The device includes: The electromagnetic shielding shell 1 has an internal cavity for accommodating the precision measurement circuit 7; Phase change material layer 5 is attached to the inner wall of the accommodating cavity; Temperature distribution plate 8 is installed inside the accommodating cavity; The thermally conductive layer 6 is used to establish the connection between the precision measurement circuit 7 and the heat spreader 8; Temperature detection and control unit 4 is mounted on the heat spreader 8; and The temperature control actuator is connected to the temperature detection and control unit 4 and actively adjusts the temperature of the temperature distribution plate 8 in a controlled manner.

[0045] In one optional embodiment, the temperature control actuator is a semiconductor cooling chip 2, the cold end of which is connected to a heat spreader 8, and the hot end of which is connected to a heat sink 3.

[0046] In one alternative embodiment, the electromagnetic shielding housing 1 is a detachable structure with an opening on one side, and is mounted on a circuit board through a screw hole structure at the edge of the opening.

[0047] The technical solution of the present invention will be described in detail below with reference to a specific embodiment.

[0048] This embodiment protects a high-precision ADC data acquisition module. The module operates in the temperature range of 20℃-30℃ and is extremely sensitive to power supply noise and external electromagnetic interference.

[0049] First, based on the dimensions of the ADC module circuit board, such as 50mm x 50mm, a rectangular electromagnetic shielding housing 1 is custom-made. Housing 1 is made of a three-layer composite material: an outer layer of 0.1mm thick aluminum foil (reflective layer), a middle layer of ferrite coating (absorbing layer), and an inner layer of insulating plastic (protection and support). Housing 1 has an opening at the bottom and M2 screw holes at the four corners of the edges.

[0050] Then, a piece of paraffin-based phase change material with a phase change temperature of 25°C was adjusted from 28°C to 25°C by adding an appropriate amount of carbon nanotubes; it was pressed into a thin sheet and attached to all the inner surfaces of the outer shell 1 except the bottom.

[0051] A ceramic-based thermal grease with a thermal conductivity >3 W / m·K is evenly applied to the main heat-generating chips on the ADC module circuit board, such as the ADC chip and the reference voltage source. The amount of grease applied is controlled to ensure that all grease layers are at a consistent height after lamination. Subsequently, a copper vapor chamber 8 of similar size is gently pressed onto the thermal grease and secured to the circuit board with clips or screws.

[0052] A digital temperature sensor, such as a DS18B20, is installed at the center of the heat spreader 8; this sensor serves as the detection terminal for the temperature detection and control unit 4. This sensor is connected to a microcontroller (MCU). The MCU has preset temperature thresholds of 28°C (upper limit) and 22°C (lower limit).

[0053] A small thermoelectric cooler 2 (TEC1-12703) is attached to one edge of a vapor chamber 8 with thermal paste at its cold end, while its hot end is connected to an aluminum heat sink 3. The power supply of the thermoelectric cooler 2 is controlled by an MCU through an H-bridge driver circuit.

[0054] Finally, insert the assembled circuit board assembly into the housing 1 from the bottom, and use screws to fix the housing 1 to the mounting holes of the circuit board to form a complete protective device.

[0055] Work process: When the ambient temperature suddenly rises to 40℃, the phase change material inside the casing 1 absorbs heat and melts, maintaining the internal ambient temperature at around 25℃ for several minutes, providing the system with buffer time. Simultaneously, the circuit itself generates heat, which is conducted to the vapor chamber 8 via thermal grease, and a temperature sensor monitors the temperature of the vapor chamber 8 in real time. When the MCU detects that the temperature exceeds 28℃, it immediately supplies power to the thermoelectric cooler 2, causing its cold end to begin cooling, rapidly reducing the temperature of the vapor chamber 8 and the connected chips. The heat generated by the hot end of the cooler is dissipated to the outside by the heat sink 3. When the temperature drops below 22℃, the MCU can reverse the current to slightly heat the circuit, or simply stop cooling, utilizing the exothermic reaction of the phase change material to maintain temperature stability.

[0056] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for protecting a precision measurement circuit, characterized in that, Includes the following steps: An electromagnetic shielding enclosure is provided, the enclosure having a receiving cavity for accommodating precision measurement circuitry; A phase change material layer is provided on the inner wall of the accommodating cavity, and the phase change temperature of the phase change material is within the normal operating temperature range of the precision measurement circuit. The precision measurement circuit is placed inside the cavity and connected to a heat spreader plate through a thermally conductive medium layer, so that the heat generated by the precision measurement circuit can be transferred to the heat spreader plate through the thermally conductive medium layer. A temperature detection and control unit is set up to detect the temperature of the heat exchange plate in real time; When the temperature of the heat exchanger exceeds a preset threshold, a temperature control actuator is activated to actively adjust the temperature of the heat exchanger.

2. The method for protecting a precision measurement circuit according to claim 1, characterized in that, The electromagnetic shielding shell is a shell made of multi-layered composite material that combines reflection loss and absorption loss, customized according to the dimensions of the precision measurement circuit.

3. A method for protecting a precision measurement circuit according to claim 1 or 2, characterized in that, The phase transition temperature of the phase change material can be adjusted by adding dopants to make it suitable for the operating temperature range of different precision measurement circuits.

4. The method for protecting a precision measurement circuit according to claim 1, characterized in that, The thermally conductive medium layer is an insulating and thermally conductive material. By controlling its coating thickness, multiple chips of different heights on the precision measurement circuit can achieve uniform planar contact with the heat spreader.

5. The method for protecting a precision measurement circuit according to claim 4, characterized in that, The insulating and thermally conductive material is ceramic-based thermally conductive silicone grease.

6. The method for protecting a precision measurement circuit according to claim 1, characterized in that, The temperature control actuator includes a thermoelectric cooler and a heat sink; when cooling is required, the thermoelectric cooler is activated, its cold end is attached to the heat spreader, and the heat generated by its hot end is dissipated through the heat sink.

7. The method for protecting a precision measurement circuit according to claim 1, characterized in that, The electromagnetic shielding shell is fixed to the circuit board by a mounting structure set at its edge.

8. A precision measurement circuit protection device, characterized in that, For implementing the method of any one of claims 1-7, the apparatus comprises: An electromagnetic shielding shell, the interior of which is formed with a cavity for accommodating precision measurement circuits; A phase change material layer is attached to the inner wall of the accommodating cavity; A temperature distribution plate is disposed within the accommodating cavity; A thermally conductive medium layer is used to establish the connection between the precision measurement circuit and the heat spreader. Temperature detection and control unit, disposed on the heat spreader plate; and The temperature control actuator is connected to the temperature detection and control unit and actively adjusts the temperature of the heat exchange plate in a controlled manner.

9. The precision measurement circuit protection device according to claim 8, characterized in that, The temperature control actuator is a semiconductor refrigeration chip, with its cold end connected to the heat spreader and its hot end connected to a heat sink.

10. The precision measurement circuit protection device according to claim 8, characterized in that, The electromagnetic shielding shell is a detachable structure with an opening on one side, and is mounted on a circuit board through a screw hole structure at the edge of the opening.

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