Heat balance high-stability digital temperature sensor packaging device and method

Abstract

The invention relates to the technical field of temperature sensors, and discloses a heat balance high-stability digital temperature sensor packaging device and method.The heat balance high-stability digital temperature sensor packaging device comprises a shell and a substrate installed in the shell, and is characterized in that a heat conduction base island is installed on the surface of the substrate, and a first chip is installed on the upper surface of the heat conduction base island; an annular cofferdam is further arranged on the surface of the substrate, and the heat conduction base island and the first chip are arranged in the annular cofferdam. The heat conduction base island is arranged on the surface of the substrate to bear the first chip, the second chip is suspended above the first chip, physical isolation in space is formed, directional migration of heat is achieved in cooperation with the capillary core section and the condensation section of the annular heat pipe and the heat conduction base island and the heat conduction column, the heat interference of heating of the first chip on the second chip is reduced, and the heat dissipation efficiency of the LED lamp is improved. Meanwhile, the annular cofferdam can prevent heat generated when other elements on the substrate work from being conducted to areas where the first chip and the second chip are located.

Description

Technical Field

[0001] This invention relates to the field of temperature sensor technology, and in particular to a thermally balanced, highly stable digital temperature sensor packaging device and method. Background Technology

[0002] The packaging structure of a digital temperature sensor is the component structure of the digital temperature sensor. It mainly involves mounting the digital temperature sensor chip through packaging to form the main body of the digital temperature sensor, which is then used in various temperature sensing devices.

[0003] An existing patent (publication number: CN113551789A) discloses a packaging structure for a digital temperature sensor, including a mounting plate. A chip packaging structure is provided on the upper surface of the mounting plate. A packaging cover base is fixedly installed on the upper surface of the mounting plate above the chip packaging structure. A chip packaging cover is fixedly installed on the upper surface of the packaging cover base.

[0004] While this application enables temperature contact via a thermally conductive resistor block below the thermally conductive opening, and the thermally conductive resistor block presses against the thermally conductive spring, firmly bonding the thermally conductive patch to the sensor chip and preventing it from detaching over time, and allowing for more accurate temperature sensing and a more comprehensive temperature sensing range through the thermally conductive opening, there are still some drawbacks. The chip inside the sensor generates heat during operation, becoming an internal "hot end." If this heat cannot dissipate quickly and evenly, it will create an uneven temperature field within the package, resulting in the measurement of a localized, "heated" temperature rather than the ambient temperature. If temperature equilibrium cannot be achieved quickly, the sensor chip will be susceptible to its own heat generation and fluctuations in the external ambient temperature during operation, making it difficult to guarantee the long-term stability and accuracy of temperature measurements. Summary of the Invention

[0005] The purpose of this invention is to provide a thermally balanced, highly stable digital temperature sensor packaging device and method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a thermal balance high-stability digital temperature sensor packaging device, comprising a housing and a substrate installed inside the housing, wherein a thermally conductive base island is mounted on the surface of the substrate, a first chip is mounted on the upper surface of the thermally conductive base island, and an annular dam is also provided on the surface of the substrate, wherein the thermally conductive base island and the first chip are disposed inside the annular dam.

[0007] The housing includes a mounting plate and a top cover. A connecting boss is fixed on the lower surface of the top cover. A support arm is fixed on the surface of the annular dam. A second chip is mounted on the surface of the support arm. The second chip is positioned above the first chip. A connecting arm is fixed on the lower surface of the connecting boss. The connecting boss can be connected to the second chip through the connecting arm. The first chip, the second chip, and the connecting boss are on the same axis.

[0008] Preferably, the annular cofferdam has a heat exchange chamber and a cooling chamber inside, and an annular heat pipe is also provided inside the annular cofferdam. The condensation section of the heat pipe is located inside the cooling chamber, which is filled with deionized water or ethanol, and the capillary wick section of the heat pipe is located inside the heat exchange chamber.

[0009] Preferably, the support arm is made of polyimide, there are multiple support arms, and the second chip is fixed at the intersection of multiple support arms. The connecting arm is made of shape memory alloy, and the lower end of the connecting arm maintains a gap of 5mm-8mm with the second chip at room temperature.

[0010] Preferably, the substrate is made of aluminum nitride ceramic, the first chip is bonded to the thermally conductive island with a high thermal conductivity adhesive, the second chip is bonded to the support arm with a thermally insulating adhesive, and the surface of the connecting boss is also coated with a thermally conductive coating.

[0011] Preferably, a heat-conducting pillar is fixed on the lower surface of the heat-conducting base island, the lower end of the heat-conducting pillar penetrates the substrate, a solder plate is fixed on the upper surface of the mounting plate, the upper surface of the solder plate is connected to the lower surface of the substrate, the lower end of the heat-conducting pillar is connected to the solder plate, and a receiving cavity is formed inside the heat-conducting base island, the receiving cavity is filled with phase change material.

[0012] Preferably, the heat-conducting pillar is divided into an extension section, a contraction section, and a connection section from top to bottom. The upper surface of the extension section is attached to the lower surface of the heat-conducting substrate island. The contraction section and the connection section are both inserted inside the substrate. The extension section is made of copper or graphene.

[0013] Preferably, a third chip is also mounted on the upper surface of the substrate. The third chip is disposed outside the annular dike, and the third chip is physically isolated from the first chip and the second chip through the annular dike.

[0014] The present invention also provides a packaging method for a thermally balanced, highly stable digital temperature sensor packaging device, comprising the following steps:

[0015] S1. The aluminum nitride ceramic substrate is cleaned and activated, and then the surface roughness is increased by plasma etching. Then, through holes for mounting heat conduction pillars are formed by laser etching at the preset position of the substrate, and the hole walls are metallized.

[0016] S2. The pre-fabricated thermally conductive island is attached to a designated area on the substrate surface using high thermal conductivity silver paste. Then, the annular dam is integrally formed on the substrate surface using low-temperature co-fired ceramic technology, so that the thermally conductive island is completely located in the central area of ​​the annular dam.

[0017] S3. Install annular heat pipes in the heat exchange chamber and cooling chamber inside the annular cofferdam. The condensing section of the heat pipe is completely immersed in the pre-injected deionized water in the cooling chamber. The capillary wick section is set inside the heat exchange chamber. After installation, the cooling chamber is sealed.

[0018] S4. Install the first chip on the upper surface of the heat-conducting base island, and use insulating adhesive to attach the second chip to the support arm surface of the annular cofferdam, ensuring that the vertical distance between the lower surface of the second chip and the upper surface of the first chip is 2.5-3mm.

[0019] S5. Pre-assemble the top cover with the connecting boss and the mounting plate to align the shape memory alloy connecting arm on the lower surface of the connecting boss with the second chip, and ensure that the lower end of the connecting arm maintains an initial gap of 5-8mm with the surface of the second chip at room temperature.

[0020] The technical effects and advantages of this invention are as follows:

[0021] 1. This invention forms a physical spatial isolation by setting a thermally conductive island on the surface of a substrate to support a first chip and suspending a second chip above the first chip. The capillary wick and condensation section of the annular heat pipe, as well as the thermally conductive island and thermally conductive pillar, enable directional heat transfer, reducing the thermal interference of the first chip's own heating on the second chip. At the same time, the annular dam can prevent the heat generated by other components on the substrate from being conducted to the areas where the first and second chips are located, ensuring that the first and second chips can perform temperature sensing in a relatively independent and stable thermal environment, thereby improving the overall measurement accuracy and anti-interference capability of the sensor.

[0022] 2. This invention achieves dynamic connection between the second chip and the connecting boss through a connecting arm made of shape memory alloy. When the ambient temperature changes, the connecting arm deforms due to the temperature change, adjusting the gap between it and the second chip. When the ambient temperature is low, a gap of 5mm-8mm is maintained to prevent the second chip from losing heat too quickly or being interfered with by external factors, ensuring its stability and sensitivity during low-temperature measurement. When the ambient temperature rises to the trigger point, the shape memory alloy undergoes a phase change, and the connecting arm bends downward to form a stable physical contact with the second chip, establishing a low thermal resistance channel from the top cover directly to the second chip, thereby achieving tracking and response to changes in external temperature at high temperatures. Attached Figure Description

[0023] Figure 1This is a three-dimensional structural diagram of a thermal balance high-stability digital temperature sensor packaging device according to the present invention;

[0024] Figure 2 This is a partial cross-sectional view of a thermal balance high-stability digital temperature sensor packaging device according to the present invention.

[0025] Figure 3 This is a partial cross-sectional view of the mounting plate in the thermal balance high-stability digital temperature sensor packaging device of the present invention.

[0026] Figure 4 This invention relates to a thermally balanced, highly stable digital temperature sensor packaging device. Figure 3 Enlarged view of point A in the middle;

[0027] Figure 5 This is a bottom view of the top cover in the thermal balance high stability digital temperature sensor packaging device of the present invention.

[0028] Figure 6 This invention relates to a thermally balanced, highly stable digital temperature sensor packaging device. Figure 5 Enlarged view of point B in the middle;

[0029] Figure 7 This is a detailed structural diagram of the thermally conductive base island and thermally conductive pillar in the thermal balance high-stability digital temperature sensor packaging device of the present invention;

[0030] Figure 8 This is a schematic diagram of the structure of the heat-conducting pillar in the thermal balance high-stability digital temperature sensor packaging device of the present invention;

[0031] Figure 9 This is a schematic diagram of the internal structure of the annular cofferdam in the thermal balance high-stability digital temperature sensor packaging device of the present invention.

[0032] In the diagram: 1. Shell; 101. Mounting plate; 102. Top cover; 2. Substrate; 3. First chip; 4. Annular dam; 401. Heat exchange chamber; 402. Cooling chamber; 403. Heat pipe; 404. Support arm; 5. Second chip; 6. Connecting boss; 601. Connecting arm; 7. Thermally conductive island; 701. Receiving cavity; 702. Thermally conductive pillar; 7021. Extension section; 7022. Contraction section; 7023. Connecting section; 8. Solder plate. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This invention provides, for example Figures 1 to 9 The thermal balance high stability digital temperature sensor packaging device shown includes a housing 1 and a substrate 2 installed inside the housing 1. A thermally conductive base island 7 is installed on the surface of the substrate 2, and a first chip 3 is installed on the upper surface of the thermally conductive base island 7. An annular dam 4 is also provided on the surface of the substrate 2, and the thermally conductive base island 7 and the first chip 3 are disposed inside the annular dam 4.

[0036] The housing 1 includes a mounting plate 101 and a top cover 102. A connecting boss 6 is fixed on the lower surface of the top cover 102. A support arm 404 is fixed on the surface of the annular dam 4. A second chip 5 is mounted on the surface of the support arm 404. The second chip 5 is positioned above the first chip 3. A connecting arm 601 is fixed on the lower surface of the connecting boss 6. The connecting boss 6 can be connected to the second chip 5 through the connecting arm 601. The first chip 3, the second chip 5, and the connecting boss 6 are on the same axis.

[0037] The annular dam 4 contains a heat exchange chamber 401 and a cooling chamber 402. An annular heat pipe 403 is also installed inside the annular dam 4. The condensation section of the heat pipe 403 is located inside the cooling chamber 402, which is filled with deionized water or ethanol. The capillary wick section of the heat pipe 403 is located inside the heat exchange chamber 401. The annular heat pipe 403 is embedded in both the heat exchange chamber 401 and the cooling chamber 402, with its capillary wick section located in the heat exchange chamber 401 near the heat source. This allows it to quickly absorb heat emitted by the first chip 3 and heat conducted laterally through the substrate 2. Excess heat is absorbed, causing the working fluid inside the tube to evaporate. Under the action of pressure difference, the vapor flows rapidly to the condensation section located in the cooling chamber 402 for condensation and heat release, transferring heat to the medium inside the cooling chamber 402. The condensed working fluid automatically flows back to the hot end by capillary force, forming a continuous phase change heat cycle. This not only avoids the second chip 5 from being affected by heat conducted laterally from other areas of the substrate 2 during the temperature sensing process, but also avoids the formation of local high temperature accumulation inside the annular dam 4, ensuring the temperature stability of the working environment of the first chip 3 and the second chip 5.

[0038] The support arms 404 are made of polyimide, and there are multiple support arms 404. The second chip 5 is fixed at the intersection of multiple support arms 404. The connecting arm 601 is made of shape memory alloy. The lower end of the connecting arm 601 maintains a gap of 5mm-8mm with the second chip 5 at room temperature. The multiple support arms 404 made of polyimide with low thermal conductivity not only provide support for the second chip 5, but also reduce the heat flow conducted from the annular dam 4 to the second chip 5, so as to achieve physical isolation between the first chip 3 and the second chip 5, and prevent the heat generated by the first chip 3 during operation from damaging the second chip 5. This has no impact on the system. Meanwhile, the connecting arm 601, made of shape memory alloy, maintains a small gap with the second chip 5 at room temperature. When the ambient temperature is low, it can prevent the second chip 5 from losing heat too quickly or being disturbed by external factors, ensuring its stability and sensitivity during low-temperature measurement. When the ambient temperature rises to the trigger point, the shape memory alloy undergoes a phase change, and the connecting arm 601 bends downward to form a stable physical contact with the second chip 5, instantly establishing a low thermal resistance channel from the top cover 102 directly to the second chip 5, thereby enabling the tracking and response to changes in external temperature under high-temperature conditions.

[0039] The substrate 2 is made of aluminum nitride ceramic. The first chip 3 is bonded to the thermally conductive base island 7 with high thermal conductivity adhesive, and the second chip 5 is bonded to the support arm 404 with thermal insulation adhesive. The surface of the connecting boss 6 is also coated with a thermally conductive coating. The use of high thermal conductivity adhesive to bond the first chip 3 to the thermally conductive base island 7 ensures that the heat generated by the first chip 3 can be conducted to the thermally conductive base island 7 below. The use of thermal insulation adhesive to bond the second chip 5 to the support arm 404 can block the heat conducted from the annular dam 4 to the support arm 404. At the same time, the thermally conductive coating on the surface of the connecting boss 6 improves the interface heat transfer efficiency between it and the shape memory alloy connecting arm 601 and between it and the top cover 102, ensuring that the ambient temperature signal can be transmitted quickly and with low loss when the connecting arm 601 is activated.

[0040] A heat-conducting pillar 702 is fixed on the lower surface of the heat-conducting base island 7, and the lower end of the heat-conducting pillar 702 penetrates the substrate 2. A soldering plate 8 is fixed on the upper surface of the mounting plate 101, and the upper surface of the soldering plate 8 is connected to the lower surface of the substrate 2. The lower end of the heat-conducting pillar 702 is connected to the soldering plate 8. A receiving cavity 701 is opened inside the heat-conducting base island 7, and the receiving cavity 701 is filled with phase change material. The heat-conducting pillar 702 forms a vertical heat flow path from the heat-conducting base island 7 to the soldering plate 8. When the heat generated by the first chip 3 is small, the phase change material is in a solid state. Its relatively low thermal conductivity helps to confine the limited heat in the base island area, making it a uniform temperature field and avoiding premature and excessive heat loss that would interfere with the accuracy of low-temperature measurement. When the power consumption and temperature of the first chip 3 increase, the phase change material absorbs heat and melts into a liquid state, and the thermal conductivity increases. This allows the heat-conducting base island 7 and the heat-conducting pillar 702 to work together to quickly conduct a large amount of heat downward, preventing the chip from overheating, thereby automatically adjusting the working state according to the actual heat load.

[0041] The heat-conducting pillar 702 is divided into an extension section 7021, a contraction section 7022, and a connecting section 7023 from top to bottom. The upper surface of the extension section 7021 is attached to the lower surface of the heat-conducting base island 7. The contraction section 7022 and the connecting section 7023 are both inserted inside the substrate 2. The extension section 7021 is made of copper or graphene, and the contraction section 7022 has honeycomb-shaped cavities inside. The top extension section 7021 is made of a high thermal conductivity material such as copper or graphene and has a large cross-sectional area, which can quickly transfer the point heat flow from the heat-conducting base island 7. Lateral diffusion and homogenization: at low power, the contraction section 7022 can suppress the downward loss of heat. Together with the phase change material above, it confines the heat locally, which is conducive to maintaining the stability of thermal balance. At high power, the strong heat flow is distributed over a large area by the extension section 7021 and impacts the contraction section 7022 with a high heat flow density. At this time, the equivalent total thermal resistance of the contraction section 7022 structure will be relatively reduced due to its large-area contact with the extension section 7021, thus transforming it into a heat conduction channel that allows a huge amount of heat flow to pass through.

[0042] A third chip 9 is also mounted on the upper surface of the substrate 2. The third chip 9 is located outside the annular dam 4. The third chip 9 is physically isolated from the first chip 3 and the second chip 5 through the annular dam 4. The placement of the third chip 9 outside the annular dam 4, together with the physical barrier of the annular dam 4, can prevent the heat generated by the third chip 9 during operation from being conducted to the areas where the first chip 3 and the second chip 5 are located. This ensures that the first chip 3 and the second chip 5 can perform temperature sensing in a relatively independent and stable thermal environment, thereby improving the overall measurement accuracy and anti-interference capability of the sensor.

[0043] When in use, under normal or low temperature measurement conditions, the connecting arm 601, made of shape memory alloy, maintains its initial shape because its temperature has not reached the phase change point, and maintains a preset gap with the second chip 5 above. At this time, the thermal resistance of the temperature sensing path is relatively high, and heat transfer is carried out by thermal radiation and limited air convection. The second chip 5 will absorb this radiant energy and gradually reach a thermal equilibrium with the top cover 102 and the connecting protrusion 6. This is beneficial to prevent the heat of the second chip 5 from being dissipated too quickly during low temperature measurement, avoid unnecessary fluctuations in its own temperature, and thus ensure the perception of small temperature changes in the environment.

[0044] Meanwhile, the weak heat generated by the first chip 3, after being conducted to the heat-conducting base island 7, is effectively confined within the area of ​​the heat-conducting base island 7 due to the combined limitation of the solid phase change material inside the base island and the high thermal resistance formed by the contraction section 7022 in the heat-conducting pillar 702. This makes the area of ​​the heat-conducting base island 7 a stable body with uniform temperature, rather than a source of heat interference. Combined with the physical isolation effect of the annular dike 4, it can prevent the second chip 5 from being affected by the heat conducted laterally from other areas of the substrate 2 during the temperature sensing process, ensuring that the second chip 5 can accurately reflect the temperature of the external environment or the object to be measured.

[0045] When the device is in a high-temperature environment or when the internal chip is in a high-power operating state, the ambient heat or the heat of the object to be measured will cause the temperature of the top cover 102 and the connecting boss 6 to rise, thereby heating the connecting arm 601 fixed on the lower surface of the connecting boss 6. When the shape memory alloy connecting arm 601 is heated to its phase transition temperature, it will bend downward and form a tight physical contact with the surface of the second unit, forming a low thermal resistance temperature sensing channel from the top cover 102 to the second chip 5, thereby enabling the external temperature change to be transmitted quickly and improving the response speed at high temperatures.

[0046] Simultaneously, the heat generated by the first chip 3 causes the temperature of the heat-conducting island 7 to rise rapidly. The phase change material inside the heat-conducting island 7 absorbs heat and quickly melts into a liquid state, increasing its thermal conductivity. This transforms the heat-conducting island 7 from a heat storage medium into a heat conductor. The heat is then transferred to the extension section 7021 at the top of the heat-conducting pillar 702. Because the extension section 7021 is made of highly thermally conductive materials such as copper or graphene and has a large cross-sectional area, it can rapidly diffuse and homogenize the heat from the heat source above, ensuring uniform heat distribution throughout the extension section 7021. Driven by the heat flow, it impacts the contraction section 7022, increasing the total heat flow through the contraction section 7022. At this point, the total thermal resistance of the contraction section 7022 is reduced due to the increased effective thermal conductivity. The area decreases, allowing heat to be quickly conducted through the contraction section 7022 to the connecting section 7023 below, and then to the soldering plate 8. When the heat generated by the heat-conducting base island 7 dissipates in all directions, it is absorbed by the capillary segment of the heat pipe 403 in the heat exchange chamber 401 inside the annular dam 4. The working fluid inside the heat pipe 403 evaporates into steam when heated, and flows to the condensation section located in the cooling chamber 402 under the action of pressure difference. After the steam exchanges heat with the deionized water in the cooling chamber 402, it condenses into liquid. The liquid flows back to the capillary segment under the action of capillary force, forming a complete phase change cycle heat dissipation path, avoiding the formation of local high temperature accumulation inside the annular dam 4, and ensuring the temperature stability of the working environment of the first chip 3 and the second chip 5.

[0047] Example 2

[0048] The present invention also provides a packaging method for a thermally balanced, highly stable digital temperature sensor packaging device, comprising the following steps:

[0049] S1. The aluminum nitride ceramic substrate 2 is subjected to surface cleaning and activation treatment. Ultrasonic cleaning is used to remove oil and impurities, followed by plasma etching to increase surface roughness and improve the bonding strength of subsequent materials. Then, through holes for mounting heat conduction pillars 702 are formed at predetermined positions on the substrate 2 by laser etching, and the hole walls are metallized to lay the foundation for welding the heat conduction pillars 702.

[0050] S2. The pre-fabricated thermally conductive island 7 is adhered to a designated area on the surface of the substrate 2 using high thermal conductivity silver paste. A pressure of 5-10N is applied and the substrate is cured at 150°C for 2 hours to ensure that the thermal resistance between the thermally conductive island 7 and the substrate 2 is less than 0.5°C / W. Subsequently, an annular dam 4 is integrally formed onto the surface of the substrate 2 using low-temperature co-fired ceramic technology, so that the thermally conductive island 7 is completely located in the central area of ​​the annular dam 4. The height of the annular dam 4 is set to 1.5 times the thickness of the substrate 2, and the distance between its inner wall and the edge of the thermally conductive island 7 is controlled at 0.8-1.2mm.

[0051] S3. Install annular heat pipes 403 in the heat exchange chamber 401 and cooling chamber 402 inside the annular cofferdam 4. The condensation section of the heat pipe 403 is completely immersed in pre-injected deionized water in the cooling chamber 402, with the injection volume being 2 / 3 of the volume of the cooling chamber 402. The capillary wick section is set inside the heat exchange chamber 401. The capillary wick is made of porous nickel metal material with a porosity controlled at 60%-70%. After installation, the cooling chamber 402 is sealed to ensure no leakage.

[0052] S4. The first chip 3 is mounted on the upper surface of the thermally conductive substrate island 7 using eutectic bonding (Au-Si eutectic bonding). The bonding temperature is controlled at 380±5℃, and the bonding time is 10-15 seconds, forming a bonding layer with a thickness of 3-5μm. The second chip 5 is bonded to the surface of the support arm 404 of the annular cofferdam 4 using insulating adhesive. The insulating adhesive is a polyimide-based adhesive with a thickness controlled at 50-80μm, ensuring that the vertical distance between the lower surface of the second chip 5 and the upper surface of the first chip 3 is 2.5-3mm. The electrical connection between the first chip 3, the second chip 5 and the substrate 2 pads is achieved by gold wire bonding. The gold wire diameter is 25μm, and the bonding strength is ≥15g.

[0053] S5. Pre-assemble the top cover 102 with the connecting boss 6 and the mounting plate 101, so that the shape memory alloy connecting arm 601 on the lower surface of the connecting boss 6 is aligned with the second chip 5. At room temperature, ensure that the lower end of the connecting arm 601 maintains an initial gap of 5-8mm with the surface of the second chip 5. Then, fasten the top cover 102 and the mounting plate 101 with bolts.

[0054] Example 3

[0055] Based on Example 1, the present invention also provides a method for preparing a thermally conductive coating, comprising the following steps:

[0056] S1. Base Treatment: The dome-shaped outer shell with protrusions is placed in a vacuum chamber, and a mixture of argon and oxygen is introduced to generate plasma. The surface of the protrusions is bombarded for 5-10 minutes to thoroughly remove organic contaminants and oxides and activate the surface.

[0057] S2, Deposited substrate bonding layer: While argon ions bombard the titanium target to generate titanium atoms, nitrogen gas is introduced to react with titanium on the substrate surface to form a titanium nitride film. The film thickness and density are controlled by controlling the N2 flow rate and sputtering time.

[0058] S3. Preparation and Coating of the Main Thermal Layer: Graphene nanosheets (negatively charged on the surface) and surface-modified micron-sized silver sheets (particle size 1-3 μm) are dispersed in a mixed solvent of deionized water and ethanol at a weight ratio of 3:7. A small amount of polyvinylpyrrolidone is added as a dispersant. The mixture is ultrasonically treated for 2 hours to form a stable and uniform slurry. The pretreated shell is grounded as the positive electrode. Using an electrostatic spray gun, the slurry is atomized and negatively charged. Under the action of the electric field, the slurry particles are directionally attracted to the surface of the protrusions to form a uniform coverage. The coated part is heat-treated in an inert atmosphere at 200-250℃ for 30-60 minutes to remove the solvent and dispersant, and to cause slight sintering on the surface of the silver particles to form a continuous thermally conductive network, firmly fixing the graphene sheets within it.

[0059] S4. Coating the surface functional layer: Surface-hydroxylated boron nitride nanotubes (BNNTs, accounting for 5-10 wt% of solid content) are uniformly dispersed in an N-methylpyrrolidone solution of polyamic acid; then, using a dispensing device, a small amount of composite solution is precisely dropped onto the top of the boss, and then a micro-area spin coating process (2000-3000 rpm, 30 seconds) is used to form an ultra-thin and uniform film; first, the temperature is maintained at 80℃ for 30 minutes to allow the solvent to evaporate, then the temperature is raised to 150℃ and maintained for 30 minutes, and then raised to 250℃ and maintained for 60 minutes. During this process, PAA dehydrates and cyclizes, transforming into stable polyimide, and BNNTs are firmly embedded in it.

[0060] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermally balanced, highly stable digital temperature sensor packaging device, comprising a housing (1) and a substrate (2) mounted inside the housing (1), characterized in that: A thermally conductive base island (7) is mounted on the surface of the substrate (2), and a first chip (3) is mounted on the upper surface of the thermally conductive base island (7). An annular dam (4) is also provided on the surface of the substrate (2). The thermally conductive base island (7) and the first chip (3) are located inside the annular dam (4). The housing (1) includes a mounting plate (101) and a top cover (102). A connecting boss (6) is fixed on the lower surface of the top cover (102). A support arm (404) is fixed on the surface of the annular dam (4). A second chip (5) is mounted on the surface of the support arm (404). The second chip (5) is located above the first chip (3). A connecting arm (601) is fixed on the lower surface of the connecting boss (6). The connecting boss (6) can be connected to the second chip (5) through the connecting arm (601). The first chip (3), the second chip (5), and the connecting boss (6) are on the same axis.

2. The thermal balance high-stability digital temperature sensor packaging device according to claim 1, characterized in that: The annular dam (4) is provided with a heat exchange chamber (401) and a cooling chamber (402). The annular dam (4) is also provided with an annular heat pipe (403). The condensation section of the heat pipe (403) is located inside the cooling chamber (402). The cooling chamber (402) is filled with deionized water or ethanol. The capillary wick section of the heat pipe (403) is located inside the heat exchange chamber (401).

3. The thermal balance high-stability digital temperature sensor packaging device according to claim 1, characterized in that: The support arm (404) is made of polyimide. There are multiple support arms (404), and the second chip (5) is fixed at the intersection of multiple support arms (404). The connecting arm (601) is made of shape memory alloy. The lower end of the connecting arm (601) maintains a gap of 5mm-8mm with the second chip (5) at room temperature.

4. The thermal balance high-stability digital temperature sensor packaging device according to claim 1, characterized in that: The substrate (2) is made of aluminum nitride ceramic. The first chip (3) is bonded to the thermally conductive island (7) with a high thermal conductivity adhesive. The second chip (5) is bonded to the support arm (404) with a thermally insulating adhesive. The surface of the connecting boss (6) is also coated with a thermally conductive coating.

5. The thermal balance high-stability digital temperature sensor packaging device according to claim 1, characterized in that: A heat-conducting pillar (702) is fixed on the lower surface of the heat-conducting base island (7). The lower end of the heat-conducting pillar (702) penetrates through the substrate (2). A welding plate (8) is fixed on the upper surface of the mounting plate (101). The upper surface of the welding plate (8) is connected to the lower surface of the substrate (2). The lower end of the heat-conducting pillar (702) is connected to the welding plate (8). A receiving cavity (701) is opened inside the heat-conducting base island (7). The receiving cavity (701) is filled with phase change material.

6. The thermal balance high-stability digital temperature sensor packaging device according to claim 5, characterized in that: The heat-conducting pillar (702) is divided into an extension section (7021), a contraction section (7022) and a connection section (7023) from top to bottom. The upper surface of the extension section (7021) is attached to the lower surface of the heat-conducting base island (7). The contraction section (7022) and the connection section (7023) are both inserted inside the substrate (2). The extension section (7021) is made of copper or graphene.

7. The thermal balance high-stability digital temperature sensor packaging device according to claim 1, characterized in that: A third chip (9) is also mounted on the upper surface of the substrate (2). The third chip (9) is located outside the annular dam (4). The third chip (9) is physically isolated from the first chip (3) and the second chip (5) through the annular dam (4).

8. A packaging method for a thermal balance high-stability digital temperature sensor packaging device, used in the thermal balance high-stability digital temperature sensor packaging device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. The aluminum nitride ceramic substrate (2) is cleaned and activated, and then the surface roughness is increased by plasma etching. Then, through holes for mounting heat conduction pillars (702) are formed by laser etching at a preset position on the substrate (2), and the hole walls are metallized. S2. The pre-made thermally conductive base island (7) is attached to a designated area on the surface of the substrate (2) using high thermal conductivity silver paste. Then, the annular dam (4) is integrally formed on the surface of the substrate (2) using low temperature co-fired ceramic technology, so that the thermally conductive base island (7) is completely located in the central area of ​​the annular dam (4). 9.S3. Install annular heat pipes (403) in the heat exchange chamber (401) and cooling chamber (402) inside the annular cofferdam (4). The condensation section of the heat pipe (403) is completely immersed in the pre-injected deionized water in the cooling chamber (402). The capillary core section is set inside the heat exchange chamber (401). After installation, the cooling chamber (402) is sealed. 10.S4. Install the first chip (3) on the upper surface of the heat-conducting base island (7), and use insulating glue to attach the second chip (5) to the surface of the support arm (404) of the annular cofferdam (4), ensuring that the vertical distance between the lower surface of the second chip (5) and the upper surface of the first chip (3) is 2.5-3mm. S5. Pre-assemble the top cover (102) with the connecting boss (6) and the mounting plate (101) so that the shape memory alloy connecting arm (601) on the lower surface of the connecting boss (6) is aligned with the second chip (5) and ensure that the lower end of the connecting arm (601) and the surface of the second chip (5) maintain an initial gap of 5-8mm at room temperature.

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