Large-scale array microsystem thermal control structure

Abstract

The invention discloses a thermal control structure of a large-scale array microsystem, which relates to the technical field of large-scale array microsystems and comprises seven microsystem sub-modules, a temperature information acquisition board, a structural framework, a cover plate and a heat conduction pad. Each microsystem sub-module is of a multi-layer structure, the middle layer is a ceramic carrier plate, an antenna array plane and a thermal resistor used for heating an equivalent chip are welded to the upper layer, and a molybdenum copper plate is welded to the lower layer to serve as a supporting structure; the micro-system sub-module is in threaded connection with the structural frame through a screw hole in the molybdenum copper plate, and the heat conduction pad is located between the micro-system sub-module and the structural frame; the temperature information acquisition board is used for reading the temperature near the thermal resistor and is connected with the micro-system sub-module through a low-frequency connector; the cover plate is in threaded connection with the structural frame, so that the problems that a large-scale array microsystem is poor in temperature uniformity and the performance is affected are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of large-scale array microsystems, and in particular relates to a thermal control component structure of a large-scale array microsystem. Background Art

[0002] Large-scale array microsystems contain a large number of RF chips, and the efficiency of RF chips is less than 40% or even lower. Therefore, more heat will be generated in the working process of the array microsystem. On the one hand, how to export heat to ensure the normal operation of the RF chip; more importantly, the performance of the RF chip is also affected by the thermal effect. Once the temperature difference between the chips is large, the working characteristics of the array surface will also deteriorate significantly. Similar to most electronic products, the heat dissipation of the array microsystem mainly transfers heat from the heat-generating chip to its own outer surface by heat conduction, and then radiates the heat to the environment by other means. In order to reduce the temperature of the microsystem chip and improve the temperature uniformity of the antenna array, the microsystem thermal management methods mainly include: efficient heat conduction and efficient heat absorption. Among them, heat conduction mainly includes optimizing the heat transfer path through structural design, improving the thermal conductivity of the heat conductor and reducing the contact thermal resistance. Common microsystem heat absorption methods mainly include air cooling, liquid cooling and passive heat dissipation relying on heat capacity and filling phase change materials.

[0003] In thermal analysis, the equivalent design is performed by combining heat source equivalence with equivalent thermal resistance extraction. The design and working conditions of the RF chip are simulated by using thermal resistors instead of ceramic chips. At the same time, the thermal conductivity and heat storage links of the array microsystem are equivalent in principle. In the equivalent process, the thermal resistance characteristics of different material properties, different heat transfer paths, and especially the thermal interface of different materials are fully considered. Compared with the principle equivalent method of single equivalent thermal resistance extraction, the effectiveness and accuracy of the equivalence can be further improved. After completing the extraction of the equivalent thermal resistance of each interface within the microsystem, the heat source equivalent model is combined to establish a thermal principle model, and the corresponding calculations are carried out.

[0004] The use of thermal controls can verify the accuracy of thermal design and thermal simulation, and provide an intuitive understanding of the thermal distribution of large-scale array microsystems. On the other hand, in the early stages of design, physical verification of thermal design can be carried out at a relatively low cost, thereby fundamentally eliminating disruptive thermal defects or thermal redundancy in product design.

[0005] The heat source of the array microsystem is mainly the chip in the antenna array. According to the currently common antenna array substrate materials of several highly integrated array microsystems, they include: HTCC (high temperature co-fired ceramic), LTCC (low temperature co-fired ceramic), PCB (printed circuit board), PCB + embedded copper. In addition, when using a substrate made of ceramic material, there will usually be a problem of thermal matching when installing the ceramic plate with a low thermal expansion coefficient with the metal structure frame, which will cause thermal stress to damage the ceramic. The commonly used thermal matching material is Kovar alloy (4J29 iron-cobalt-nickel alloy) with a low thermal expansion coefficient, but the thermal conductivity is only 17 (W / m·K), which makes it difficult to quickly export the heat generated by the chip. Summary of the invention

[0006] The purpose of the present invention is to provide a large-scale array microsystem thermal control structure to solve the problem of poor temperature uniformity of the large-scale array microsystem, which affects the performance.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] In one aspect, the present specification provides a large-scale array microsystem thermal control structure, comprising:

[0009] 7 microsystem submodules, a temperature information acquisition board, a structural frame, a cover plate and a thermal pad; the microsystem submodule is a multi-layer structure, the middle layer is a ceramic carrier board, the upper layer is welded with an antenna array and a thermal resistor for equivalent chip heating, and the lower layer is welded with a molybdenum copper plate as a supporting structure; the microsystem submodule is screwed to the structural frame through the screw holes on the molybdenum copper plate, and the thermal pad is located between the microsystem submodule and the structural frame; the temperature information acquisition board is used to read the temperature near the thermal resistor and is connected to the microsystem submodule through a low-frequency connector; the cover plate is screwed to the structural frame.

[0010] On the other hand, the present specification provides a method for verifying a large-scale array microsystem thermal control structure, comprising:

[0011] Step 102, using Ansys IcePak software to perform thermal simulation analysis on the simplified model of the thermal control structure to obtain a first maximum temperature difference value;

[0012] Step 104, using a contact thermocouple to directly measure the antenna array surface temperature of the microsystem submodule of the thermal control structure to obtain a second maximum temperature difference value;

[0013] Step 106, reading the temperature information of the temperature information acquisition board to obtain a third maximum temperature difference value;

[0014] Step 108 , performing performance verification based on the first maximum temperature difference value, the second maximum temperature difference value, the third maximum temperature difference value, and the maximum temperature difference threshold value to obtain a verification result.

[0015] Based on the above technical solution, this specification can achieve the following technical effects:

[0016] This structure uses thermal resistors to generate heat equivalently instead of large-scale array microsystems, which can verify the thermal performance of the system in advance. It uses the HTCC high-temperature co-fired ceramic substrate welded with a molybdenum-copper plate to quickly extract the heat from the chip / thermal resistor. It uses high thermal conductivity materials such as graphene thermal foam and copper alloy to achieve efficient heat dissipation of the system. This efficient heat dissipation structural design solves the problem of uneven temperature distribution in large-scale array microsystems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a schematic diagram of the structure of a large-scale array microsystem thermal control unit in one embodiment of the present invention.

[0018] Figure 2 Schematic diagram of the microsystem submodule structure in one embodiment of the present invention.

[0019] Figure 3 This is a temperature cloud diagram of a large-scale array microsystem thermal control unit thermal simulation system in one embodiment of the present invention.

[0020] Figure 4 This is a temperature cloud diagram of thermal resistors for thermal simulation of a large-scale array microsystem thermal control unit in one embodiment of the present invention.

[0021] Figure 5 The figure is a temperature curve of measurement points on the array surface read out from a large-scale array microsystem thermal control test in one embodiment of the present invention.

[0022] 1. Microsystem submodule 2. Thermal pad 3. Structural frame 4. Temperature information acquisition board 5. Cover plate 6. Antenna array 7. Thermal resistor 8. Ceramic carrier 9. Molybdenum copper plate DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0024] It should be noted that, in order to clearly explain the content of the present invention, the present invention specifically cites multiple embodiments to further illustrate different implementations of the present invention, wherein the multiple embodiments are enumerated rather than exhaustive. In addition, for the sake of brevity of explanation, the contents mentioned in the previous embodiments are often omitted in the subsequent embodiments. Therefore, the contents not mentioned in the subsequent embodiments can refer to the previous embodiments accordingly.

[0025] Example 1

[0026] Please refer to Figure 1 , Figure 1 The following is a large-scale array microsystem thermal control structure provided by this embodiment. In this embodiment, the structure includes: 7 microsystem submodules, a temperature information acquisition board, a structural frame, a cover plate and a thermal pad; the microsystem submodule is a multi-layer structure, the middle layer is a ceramic carrier board, the upper layer is welded with an antenna array and a thermal resistor for equivalent chip heating, and the lower layer is welded with a molybdenum copper plate as a supporting structure; the microsystem submodule is screwed to the structural frame through the screw holes on the molybdenum copper plate, and the thermal pad is located between the microsystem submodule and the structural frame; the temperature information acquisition board is used to read the temperature near the thermal resistor and is connected to the microsystem submodule through a low-frequency connector; the cover plate is screwed to the structural frame.

[0027] In this embodiment, the structural frame is an embedded box structure, the microsystem submodule is installed in the cavity and the structural frame has an opening for placing a low-frequency connector.

[0028] In this embodiment, the material of the thermal pad is flexible and is graphene foam; the thermal conductivity of the thermal pad in the thickness direction perpendicular to the mounting surface is 30 (W / m·K), and the thermal conductivity in the width direction facing the mounting surface is 100 (W / m·K).

[0029] In this embodiment, the material of the structural frame is copper alloy, and the thermal conductivity is 1100 (W / m·K).

[0030] In this embodiment, the ceramic carrier is used to carry a thermal resistor and serve as a mounting carrier for components; the material of the ceramic carrier is HTCC, and the thermal conductivity is 15.6 (W / m·K).

[0031] In this embodiment, the molybdenum-copper plate is used for heat dissipation, and its thermal conductivity is 200 (W / m·K).

[0032] Specifically, the large-scale array microsystem thermal control structure provided in this embodiment includes: a microsystem submodule, a temperature information acquisition board, a structural frame, a cover plate and a thermal pad.

[0033] Among them, reference Figure 2 The microsystem submodule is welded with a multi-layer structure. The middle layer is a ceramic carrier board, the upper layer is welded with antenna arrays and equivalent chips for heat resistance, and the lower layer is welded with molybdenum copper plates as structural support.

[0034] Among them, the thermal control antenna array surface is consistent with the array microsystem antenna array surface design, which improves the accuracy of verifying the heat dissipation performance of the array microsystem through the thermal control.

[0035] It should be noted here that the thermal resistor is the heat source for the thermal control to simulate the heat generation of the array microsystem chip. The thermal resistor is used in the design to perform equivalent calculations on the heat generation of the RF chip. The heat consumption of the chip in the array microsystem is 2.34W, and the heat consumption of the chip is 0.468W under the condition of 20% duty cycle. The total heat consumption of the 16 chips in a single microsystem submodule is 7.776W. The thermal resistor is a 0.5W chip resistor from Bedis Electronics Co., Ltd. The resistor brand is CRW1216-100R-5%-250PPM. The resistance of a single thermal resistor is 100 ohms. The 16 thermal resistors are connected in parallel in the design, and the total resistance of the microsystem submodule is 6.25 ohms (parallel resistance = 100 / 16 = 6.25 ohms). According to the equivalent calculation of the total resistance of the submodule of 6.25 ohms, under the working state of 7V / 1.11A, the microsystem thermal control submodule can achieve the heat consumption equivalent to the 7.776W microsystem submodule (20% duty cycle).

[0036] Among them, the structural frame material is metal, which serves as the main supporting structure and installation reference of the thermal control unit of the large-scale array microsystem. The microsystem submodule is screwed to the frame through the screw holes on the molybdenum copper plate, and a thermal pad is placed between the molybdenum copper plate and the structural frame. Among them, the structural frame material is a copper alloy with good thermal conductivity, and the thermal conductivity of the material is 1100 (W / m·K). Its structure is an embedded box structure, which provides an installation reference for the array microsystem and also serves as the main heat sink. The mounting surface of the microsystem submodule is flat. Except for the slots through which the connector passes, the contact area is as large as possible, which improves the heat dissipation efficiency, quickly conducts the heat transferred from the molybdenum copper and radiates the heat to the environment.

[0037] The temperature information acquisition board is an integrated circuit board, whose main function is to read the temperature near the thermal resistor and is connected to the microsystem submodule through a low-frequency connector. The temperature information acquisition board and the cover are fixed to the lower side of the frame by screws.

[0038] Among them, the thermal pad material is graphene foam, which has a certain compression ratio and good surface thermal conductivity. The thermal conductivity in the thickness direction perpendicular to the installation surface is 30 (W / m·K), and the surface thermal conductivity is 100 (W / m·K). The thermal conductivity has certain advantages in flexible interface thermal conductive materials, and can reduce the contact thermal resistance caused by the processing error and assembly error of the molybdenum copper plate and the structural frame.

[0039] Among them, the ceramic carrier is used as the mounting carrier for thermal resistors and components. Its material is HTCC, which has the best thermal conductivity among the same type of materials, with a thermal conductivity of 15.6 (W / m·K), which transfers the heat generated by the thermal resistor to molybdenum copper. Molybdenum copper is welded under the ceramic carrier, with a high thermal conductivity of 200 (W / m·K) and a low thermal expansion coefficient. Its function is to dissipate heat and provide thermal matching between the ceramic carrier and the structural frame of the metal material, avoiding damage to the fragile ceramic carrier due to stress caused by temperature changes.

[0040] For example, the overall dimensions of the large-scale array microsystem thermal control unit mentioned in this embodiment are 175 mm long and 140 mm wide, and the total thickness is controlled within 20 mm, which is only 19 mm. It aims to complete the heat dissipation design of the microsystem with extremely small thickness and improve the system integration.

[0041] The size of the microsystem submodule is 36.8mm×36.8mm. Seven microsystem submodules constitute the main working module of this thermal control. In the array microsystem design simulated by the thermal control, the microsystem submodule can control the antenna array to send and receive signals through the chip to realize the microsystem function. Among them, the chip is the main heat-generating component in the system. Through power calculation and in-situ replacement with a thermal resistor with the same heat-generating power, the thermal control and the array microsystem heat source position and heat-generating power are the same, which improves the accuracy of the thermal control to verify the heat dissipation and temperature uniformity.

[0042] The limited size in the thickness direction means that the system can only dissipate heat in the length and width directions. Therefore, the structural frame, as the main structural support of the system, also needs to play a role in heat dissipation. Copper is selected as the structural frame material to increase thermal conductivity and improve the heat dissipation performance of the microsystem. Affected by the processing and surface quality of the structural parts, there is a certain contact thermal resistance between the contact surface of the molybdenum copper and the structural frame after screw installation, and the coordination of the installation of each submodule will also lead to differences in contact thermal resistance. Therefore, adding a layer of interface thermal conductive material with a certain degree of compressibility between the molybdenum copper plate and the structural frame solves the problem of different contact thermal resistances of each submodule.

[0043] In summary, this structure uses thermal resistors to generate heat to replace large-scale array microsystems, which can verify the thermal performance of the system in advance. The HTCC high-temperature co-fired ceramic substrate welded with a molybdenum-copper plate is used to quickly extract the heat of the chip / thermal resistor. High thermal conductivity materials such as graphene thermal foam and copper alloy are used to achieve efficient heat dissipation of the system. This efficient heat dissipation structural design solves the problem of uneven temperature distribution in large-scale array microsystems.

[0044] Example 2

[0045] This embodiment provides a method for verifying the thermal control structure of a large-scale array microsystem. In this embodiment, the method includes:

[0046] Step 102, using Ansys IcePak software to perform thermal simulation analysis on the simplified model of the thermal control structure to obtain a first maximum temperature difference value;

[0047] In this embodiment, the simulation environment temperature of the thermal simulation analysis is 25° C., and the simulation working time is 100 seconds.

[0048] Step 104, using a contact thermocouple to directly measure the antenna array surface temperature of the microsystem submodule of the thermal control structure to obtain a second maximum temperature difference value;

[0049] In this embodiment, one implementation of step 104 is:

[0050] Step 202, first preheating the thermal control structure;

[0051] Step 204, after preheating is completed, a contact thermocouple is used to directly measure the center point temperature of the antenna array surface of the seven microsystem submodules;

[0052] Step 206, calculating the temperature difference between the center points of the antenna array surfaces of each of the microsystem submodules to obtain a second maximum temperature difference value.

[0053] Step 106, reading the temperature information of the temperature information acquisition board to obtain a third maximum temperature difference value;

[0054] Step 108 , performing performance verification based on the first maximum temperature difference value, the second maximum temperature difference value, the third maximum temperature difference value, and the maximum temperature difference threshold value to obtain a verification result.

[0055] In this embodiment, the maximum temperature difference threshold is 8°C;

[0056] In this embodiment, one implementation of step 108 is:

[0057] If the first maximum temperature difference value, the second maximum temperature difference value, and the third maximum temperature difference value are all smaller than the maximum temperature difference threshold value, the verification result is that the heat dissipation performance is good and the temperature uniformity is good.

[0058] Specifically, in order to verify the heat dissipation effect of the large-scale array microsystem thermal control structure of the present invention, the simplified structural model was simulated using Ansys IcePak thermal simulation software. The simulation environment was set to an ambient temperature of 25°C and a working time of 100s. The simulation results are shown in Figure 2. Figure 3 , 4 As shown in the figure, the temperature range of the large-scale array microsystem thermal control unit is 26.2282℃~45.2293℃, of which the temperature range of the thermal resistor is 38.2782℃~45.2293℃, and the temperature difference is 6.9509℃. The simulation results show that the uniformity of temperature is <8℃, which meets the use requirements of large-scale array microsystems.

[0059] At the same time, reference Figure 5 The heat dissipation effect of the large-scale array microsystem thermal control structure of the present invention is verified by experiments. The thermal control is preheated before testing, and the antenna array surface temperature of each microsystem sub-module is directly measured using a contact thermocouple. The center points of the array surfaces of 7 microsystem sub-modules are taken for testing. After testing, the maximum temperature difference of the array surface temperature monitoring points measured by the large-scale array microsystem thermal evaluation component is 7.67°C, which meets the array surface temperature uniformity of ≤8°C.

[0060] After the test, the temperature information was read. The temperature near the chip at the 100th second of operation measured by the temperature information acquisition board is shown in Table 2, where the position in the table corresponds to the actual position of the thermal resistor in the large-scale array microsystem submodule, in °C. From the temperature record table, it can be seen that the temperature range of the thermal resistor is 44.1°C to 51.5°C, and the maximum temperature difference is 7.4°C, which meets the array surface temperature uniformity of ≤8°C.

[0061] Table 2 The temperature data of each thermal resistor read by the temperature information acquisition board when the thermal control unit works for 100s

[0062] null null 47.6 48.1 48.5 48.0 44.8 45 44.6 44.4 null null null null 48.3 49.2 50.2 48.6 45.2 45.4 45.2 44.1 null null null null 49.1 50.3 50.6 50.2 46.1 45.5 45.2 44.1 null null null null 49.7 50.8 51.1 50.7 46.8 46.2 45.1 44 null null 48.5 49.2 50.5 51.5 50.9 50.5 50.1 49.5 46.4 45.9 45.9 45.1 47.2 47.5 49.4 50.6 50.2 50.4 50 49.5 46.4 45.9 45.9 44.6 45.2 45.9 47.2 49.2 50.2 50 49.9 49.4 46.4 45.2 45.5 44.4 44 44.5 46.8 48.8 50 50.2 49.9 48.6 45.5 44.9 44.8 44.2 null null 44.5 45.9 48.1 50.1 50.5 50.2 50.2 50.6 null null null null 44.9 46.6 47.9 49.2 48.5 48.1 48.1 48.9 null null null null 45.9 46.8 47.5 48.8 46.9 46.1 46.6 47.4 null null null null 46 46.9 47.4 48.2 45.2 45.1 46.2 46.8 null null

[0063] The large-scale array microsystem thermal control structure provided in this specification is measured by three test methods. The maximum temperature difference of each sub-module of the thermal control is 7.67°C. The temperature difference does not exceed 8°C, which proves that the structure of the present invention can minimize the performance gap caused by the temperature difference of each chip, and provides an effective and feasible structural scheme for the design of large-scale array microsystems, which can guide the design of corresponding large-scale array microsystems.

[0064] The above is a description of a specific embodiment of the present specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the specific order or sequential order shown in the process depicted in the drawings is not necessarily required to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0065] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A large-scale array microsystem thermal control structure, characterized in that: include: 7 microsystem submodules, temperature information acquisition board, structural frame, cover plate and thermal pad; The microsystem submodule is a multi-layer structure, the middle layer is a ceramic carrier, the upper layer is welded with an antenna array and a thermal resistor for equivalent chip heating, and the lower layer is welded with a molybdenum copper plate as a supporting structure; The microsystem submodule is screwed to the structural frame through the screw holes on the molybdenum copper plate, and the thermal pad is located between the microsystem submodule and the structural frame; the temperature information acquisition board is used to read the temperature near the thermal resistor and is connected to the microsystem submodule through a low-frequency connector; the cover plate is screwed to the structural frame.

2. The large-scale array microsystem thermal control structure according to claim 1, characterized in that: The structural frame is an embedded box structure, the microsystem submodule is installed in the cavity and the structural frame has an opening for placing a low-frequency connector.

3. The large-scale array microsystem thermal control structure according to claim 1, characterized in that: The material of the thermal pad is flexible and is graphene foam; the thermal conductivity of the thermal pad in the thickness direction perpendicular to the mounting surface is 30 (W / m·K), and the thermal conductivity in the width direction facing the mounting surface is 100 (W / m·K).

4. The large-scale array microsystem thermal control structure according to claim 1, characterized in that: The material of the structural frame is copper alloy, and the thermal conductivity is 1100 (W / m·K).

5. The large-scale array microsystem thermal control structure according to claim 1, characterized in that: The ceramic carrier is used to carry thermal resistors and as a mounting carrier for components; the material of the ceramic carrier is HTCC, and the thermal conductivity is 15.6 (W / m·K).

6. The large-scale array microsystem thermal control structure according to claim 1, characterized in that: The molybdenum copper plate is used for heat dissipation, and has a thermal conductivity of 200 (W / m·K).

7. A verification method for the thermal control structure of a large-scale array microsystem according to any one of claims 1 to 6, characterized in that: include: Using Ansys IcePak software to perform thermal simulation analysis on a simplified model of the thermal control structure to obtain a first maximum temperature difference value; Using a contact thermocouple to directly measure the antenna array surface temperature of the microsystem submodule of the thermal control structure to obtain a second maximum temperature difference value; Read the temperature information of the temperature information acquisition board to obtain the third maximum temperature difference value; Performance verification is performed based on the first maximum temperature difference value, the second maximum temperature difference value, the third maximum temperature difference value, and the maximum temperature difference threshold to obtain a verification result.

8. The verification method according to claim 7, characterized in that: The simulation environment temperature of the thermal simulation analysis is 25° C., and the simulation working time is 100 s.

9. The verification method according to claim 7, characterized in that: The step of directly measuring the antenna array surface temperature of the microsystem submodule of the thermal control structure by using a contact thermocouple to obtain the second maximum temperature difference value comprises: Firstly, the thermal control structure is preheated; After preheating, contact thermocouples were used to directly measure the center point temperature of the antenna array of the seven microsystem submodules; The temperature difference between the center points of the antenna array surfaces of each of the two microsystem submodules is calculated to obtain the second maximum temperature difference value.

10. The verification method according to claim 7, characterized in that: The maximum temperature difference threshold is 8°C; The performance verification is performed based on the first maximum temperature difference value, the second maximum temperature difference value, the third maximum temperature difference value and the maximum temperature difference threshold, and the verification result is obtained including: If the first maximum temperature difference value, the second maximum temperature difference value, and the third maximum temperature difference value are all smaller than the maximum temperature difference threshold value, the verification result is that the heat dissipation performance is good and the temperature uniformity is good.

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