Planar heating structure, low-temperature equipment and preparation method of planar heating structure

Abstract

The invention relates to the technical field of low-temperature equipment, and provides a planar heating structure, low-temperature equipment and a preparation method of the planar heating structure, the planar heating structure comprises a resistance heating layer and a surface insulating layer, the resistance heating layer comprises a conductive trace, and the conductive trace is coated and cured in a target area of a heated part by a conductive material. The conductive trace is electrically insulated from the heated component, and two ends of the conductive trace are connected with an external power supply; the surface insulating layer is coated with an insulating material and cured outside the conductive trace. The conductive trace and the surface insulating layer are both formed through a coating process, the coating process can adapt to heated parts with different shapes, and even if the target area is a curved surface or other complex shapes, the conductive trace and the surface insulating layer can be well attached to the target area, so that the heating effect is ensured, and the heating efficiency is improved. The problem that in the prior art, a heating piece is poor in adaptability to a heated component with the complex appearance is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-temperature equipment, and in particular to a planar heating structure, a low-temperature equipment and a preparation method of the planar heating structure. BACKGROUND

[0002] In the fields of frontier such as cryogenics, space technology and semiconductor process, the accurate temperature control of the internal devices of the low-temperature and ultra-high vacuum equipment is crucial. The efficient and uniform heating is the key to ensure the stable performance of the devices and the success of the experiments.

[0003] At present, a common temperature control scheme is to use a pasting type thin film heater for heating. The scheme mainly realizes the heating by fixing a preformed heating sheet on the surface of a component to be heated through an adhesive. This way can provide the component with the required heat to a certain extent.

[0004] However, the heating sheet in the related art is usually a preformed sheet structure. When the outer shape of the component to be heated is relatively complex, for example, the component to be heated has a curved surface, a step or a special-shaped structure, the preformed heating sheet is difficult to perfectly fit the surface of the special-shaped structure. The incomplete fitting of the heating sheet and the surface of the component to be heated causes a gap between the heating sheet and the surface of the component to be heated, affects the heat conduction efficiency, causes uneven heat distribution, limits the heating effect and cannot meet the demand of high-precision temperature control.

[0005] Therefore, how to solve the problem that the heating sheet in the related art has poor adaptability to the complex outer shape of the heated component becomes an important technical problem to be solved by the person skilled in the art. SUMMARY

[0006] The present application provides a planar heating structure, a low-temperature equipment and a preparation method of the planar heating structure to solve the defect that the heating sheet in the related art has poor adaptability to the complex outer shape of the heated component.

[0007] The present application provides a planar heating structure, comprising: a resistive heating layer comprising a conductive trace coated and solidified by a conductive material on a target region of a heated component, the conductive trace being electrically insulated from the heated component, and two ends of the conductive trace being used for connecting an external power supply; a surface insulating layer coated and solidified by an insulating material on the outside of the conductive trace.

[0008] According to the planar heating structure provided by the present application, the planar heating structure further comprises: a bottom insulating layer coated and solidified by an insulating material on the target region of the heated component, and the conductive trace being formed on the surface of the bottom insulating layer.

[0009] According to the planar heating structure provided by the application, the conductive traces have a consistent distribution density in the target area. The conductive traces are formed by reciprocally arranging a plurality of spaced-apart trace segments and alternately connecting the ends of the trace segments, each of the trace segments has a periodic wave profile, the wave profiles of the plurality of trace segments are arranged in phase, and the spacing between any two adjacent trace segments is equal.

[0010] According to the planar heating structure provided by the application, the conductive traces are formed by a screen printing process.

[0011] According to the planar heating structure provided by the application, the planar heating structure further comprises: Conductive leads, each end of the conductive traces corresponds to one of the conductive leads, the conductive leads are electrically connected to the ends of the conductive traces, and the conductive leads are used to connect the external power supply.

[0012] According to the planar heating structure provided by the application, the conductive leads are fixed to the ends of the conductive traces by conductive glue.

[0013] According to the planar heating structure provided by the application, the insulating material comprises one of low-temperature insulating varnish and low-temperature epoxy resin. And / or, the conductive material comprises one of graphite-based conductive paint and nano-conductive material ink. And / or, the conductive leads are made of manganese-copper alloy.

[0014] The application also provides a low-temperature device comprising the planar heating structure.

[0015] The application also provides a preparation method of the planar heating structure, which is used to prepare the planar heating structure on a heated component, and the preparation method comprises the following steps: Preprocessing a target area of the heated component, the preprocessing comprises surface roughening treatment and surface cleaning treatment; Printing conductive material on the target area of the heated component by a screen printing process to form conductive traces, until the resistance value of the conductive traces reaches a preset resistance value; After the conductive material is solidified, conductive leads are bonded and fixed on both ends of the conductive traces by conductive glue, and the conductive glue is solidified; Coating insulating material on all exposed surfaces of the conductive traces and the conductive glue; Baking and solidifying in a vacuum environment.

[0016] The preparation method of the planar heating structure further comprises the following steps before printing the conductive material on the target region of the heated component: Applying an insulating material to the target region of the heated component and performing baking and curing.

[0017] The planar heating structure comprises a resistance heating layer and a surface insulating layer. The resistance heating layer comprises a conductive trace coated and cured on the target region of the heated component by a conductive material. The two ends of the conductive trace are used to connect an external power supply. The conductive trace has a certain resistance value. By passing current through the conductive trace, the conductive trace can generate Joule heat, thereby achieving heating of the target region of the heated component. The conductive trace is electrically insulated from the heated component, avoiding the problem of short circuit between the conductive trace and the heated component. The surface insulating layer is coated and cured on the outside of the conductive trace by an insulating material, providing electrical insulation and physical protection for the conductive trace. The conductive trace and the surface insulating layer are formed by a coating process, which can adapt to different shapes of the heated component. Even if the target region of the heated component has a complex profile such as a curved surface, the coating process can be performed along the complex profile. The conductive trace and the surface insulating layer can be well fitted to the target region, and there is no gap between the conductive trace and the target region of the heated component, ensuring heat conduction efficiency and heating effect. In this way, the problem of poor adaptability of the heating sheet to the heated component with complex shape in the related art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Fig. 1 is a cross-sectional structure schematic diagram of the planar heating structure formed on the circumferential surface of the heated component according to the present application.

[0020] Fig. 2 is a schematic diagram of the geometric shape of the conductive trace according to the present application.

[0021] Reference signs: 101, target region; 102, bottom insulating layer; 103, resistance heating layer; 104, surface insulating layer; 201, heated component; 202, conductive trace; 2021, trace segment; 203, electrical connection point; 301, external power supply; 302, conductive lead. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in conjunction with the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] The present application will be described below in conjunction with Figs. 1-2 The planar heating structure of the present application is described.

[0024] As Figs. 1-2 shown, the planar heating structure provided by the embodiment of the present application comprises a resistance heating layer 103 and a surface insulation layer 104.

[0025] Specifically, the resistance heating layer 103 comprises a conductive trace 202 coated and solidified on a target area 101 of a heated component 201 by a conductive material. Two ends of the conductive trace 202 are used to connect an external power supply 301, and the conductive trace 202 has a certain resistance value. By passing current through the conductive trace 202, the conductive trace 202 can generate Joule heat, thereby realizing heating of the target area 101 of the heated component 201.

[0026] The conductive trace 202 is electrically insulated from the heated component 201, avoiding the problem of short circuit between the conductive trace 202 and the heated component 201. The surface insulation layer 104 is coated and solidified on the outside of the conductive trace 202 by an insulating material, covering and packaging the conductive trace 202, providing electrical insulation and physical protection, and avoiding interference and mechanical damage from the external environment.

[0027] The conductive trace 202 and the surface insulation layer 104 are both formed by a coating process, which can adapt to different shapes of the heated component 201. Even if the target area 101 of the heated component 201 has a complex profile such as a curved surface, the coating process can still be performed along the complex profile. The conductive trace 202 and the surface insulation layer 104 can be well fitted to the target area 101, and there is no gap between the conductive trace 202 and the target area 101 of the heated component 201, ensuring the heat conduction efficiency and guaranteeing the heating effect.

[0028] In this way, the problem of poor adaptability of the heating sheet to the heated component 201 with a complex shape in the related art is solved.

[0029] It should be noted that before the conductive trace 202 is formed on the target region 101 of the heated component 201, roughening treatment such as sandblasting treatment can be performed on the target region 101 of the heated component 201 to increase the roughness of the target region 101 of the heated component 201, so as to enhance the bonding strength between the conductive trace 202 and the target region 101 of the heated component 201, to enable the conductive trace 202 to withstand the thermal expansion and contraction stress in the deep cryogenic cycle, to improve the structural reliability of the planar heating structure, and to avoid delamination or peeling failure.

[0030] The material of the heated component 201 is generally a metal or a non-metal with excellent thermal conductivity.

[0031] In some embodiments, the heated component 201 is made of insulating materials such as special ceramics, and in this case, the conductive trace 202 can be directly formed on the target region 101 of the heated component 201.

[0032] In other embodiments, the material of the heated component 201 is a conductive material such as oxygen-free copper or aluminum, and in this case, the target region 101 of the heated component 201 needs to be insulated to ensure that the conductive trace 202 is insulated from the heated component 201.

[0033] Specifically, the planar heating structure further comprises a bottom insulating layer 102, and the conductive trace 202 is formed on the surface of the bottom insulating layer 102. The bottom insulating layer 102 formed between the conductive trace 202 and the target region 101 of the heated component 201 can prevent short circuit between the conductive trace 202 and the heated component 201.

[0034] The bottom insulating layer 102 is coated and cured on the target region 101 of the heated component 201, and the bottom insulating layer 102 has excellent adhesion with the target region 101 of the heated component 201, which can ensure the adhesion of the conductive trace 202 with the bottom insulating layer 102 and the target region 101 of the heated component 201, and ensure the heating effect.

[0035] Since the bottom insulating layer 102 is in direct contact with the target region 101 of the heated component 201, the heat generated by the conductive trace 202 can be quickly and efficiently transferred to the heated component 201 through the extremely thin bottom insulating layer 102. Compared with the conventional technology of sticking a preformed heating sheet to the heated component 201 by an adhesive, the present embodiment can avoid the problems of high thermal resistance and thermal hysteresis caused by the adhesive, and is beneficial to improve the response speed of temperature control and heating efficiency.

[0036] The bottom insulating layer 102 is coated and cured in situ. The bottom insulating layer 102 completely wets and fills the micro-pits on the surface of the target area 101 at the molecular level, achieving a seamless and tight bond, eliminating the contact thermal resistance of traditional physical interfaces, and improving the continuity and efficiency of heat conduction.

[0037] The thickness of the bottom insulating layer 102 is 20~30 micrometers.

[0038] In this embodiment, the conductive traces 202 have a consistent distribution density in the target area 101, and the Joule heat generated when energized can be evenly distributed in the target area 101 of the heated component 201, which can ensure uniform heating of the target area 101 of the heated component 201.

[0039] The conductive trace 202 is formed by multiple spaced trace segments 2021 arranged back and forth and connected alternately at the ends, with equal spacing between any two adjacent trace segments 2021. Each trace segment 2021 has a periodic wavy profile, and the wavy profiles of multiple trace segments 2021 are arranged in phase.

[0040] In other words, a conductive trace 202 is provided, and both ends of the conductive trace 202 are used to connect to an external power supply 301. The conductive trace 202 has multiple trace segments 2021 connected in series. The axes of the multiple trace segments 2021 are parallel, and the multiple trace segments 2021 are distributed at intervals and evenly. The distribution direction of the multiple trace segments 2021 is perpendicular to the axis of the trace segments 2021.

[0041] This serpentine layout allows the conductive traces 202 to cover the entire target area 101 with a consistent distribution density. The conductive traces 202 as a whole form a uniform planar heat source, thereby ensuring uniform heating of the target area 101 of the heated component 201.

[0042] Specifically, the shape of the conductive trace 202 can be as follows: Fig. 2 As shown, Fig. 2 This diagram only illustrates the wave contours and relative positions of multiple trace segments 2021; the width of each trace segment 2021 and the distance between adjacent trace segments 2021 are not specified. The width of each trace segment 2021 and the distance between adjacent trace segments 2021 can be determined based on factors such as the resistance value and heating efficiency of the conductive trace 202. Generally, the distance between adjacent trace segments 2021 is on the order of millimeters, but the specific distance is not limited and can be determined through multiple experiments and adjustments. Relative to the thickness of the target area 101 of the heated component 201, heat will rapidly diffuse laterally and homogenize when conducted into the interior of the heated component 201.

[0043] In this embodiment, the conductive trace 202 is formed by a screen printing process. The screen printing process can accurately print the conductive material on the target area 101 of the heated component 201 according to a pre-designed path with a complex shape such as a snake shape, and can ensure that the conductive trace 202 has a uniform distribution density in the target area 101. Moreover, the screen printing process is standardized and controllable, and the resistance value of the conductive trace 202 can be accurately regulated by repeated printing, so as to accurately control the final heating power. Moreover, the performance of different batches of products can be highly consistent and repeatable.

[0044] In addition, the conductive trace 202 is integrally formed by the screen printing process. The plurality of trace segments 2021 are not connected together at a later stage, but are integrally formed during the screen printing.

[0045] In the embodiment of the present application, the planar heating structure further comprises a conductive lead 302, and the two ends of the conductive trace 202 correspond to one conductive lead 302 respectively. The conductive lead 302 is electrically connected to the end of the conductive trace 202, and the conductive lead 302 is used to connect an external power source 301, so as to provide stable power input for the conductive trace 202, so as to realize the heating function of the heated component 201.

[0046] The conductive lead 302 is fixed to the end of the conductive trace 202 by conductive glue, so as to form a high-strength and low-resistance electrical connection point 203. The electrical connection point 203 can ensure the reliability and low loss of current transmission, and can also ensure that the electrical connection point 203 is not easy to fall off or fail when subjected to repeated deep low-temperature and high-temperature cycle impact, so as to improve the long-term working reliability of the planar heating structure.

[0047] The conductive glue can be conductive silver epoxy resin.

[0048] The material of the conductive lead 302 is manganese copper alloy. The resistivity of the manganese copper alloy changes little with temperature. By using this characteristic, the power fluctuation caused by the significant change of the resistance of the conductive lead 302 itself in a low-temperature environment can be effectively avoided, so as to ensure the stability of the heating power and the accuracy of the temperature control in a wide temperature range.

[0049] In this embodiment, the insulating material used to form the bottom insulating layer 102 and the surface insulating layer 104 includes one of a low-temperature insulating varnish and a low-temperature epoxy resin. The low-temperature insulating varnish and the low-temperature epoxy resin can still provide excellent electrical insulation performance in a deep cryogenic environment, while having extremely low outgassing rate, and can completely remove residual gas through vacuum baking and curing, thereby ensuring perfect compatibility of the planar heating structure with an ultra-high vacuum environment and avoiding pollution to the vacuum system. In addition, the low-temperature insulating varnish and the low-temperature epoxy resin have good thermal conductivity and firm adhesion to the substrate, can effectively withstand severe temperature change impact, and improve the long-term reliability of the structure.

[0050] The conductive material includes one of a graphite-based conductive paint and a nano-conductive material ink.

[0051] The graphite-based conductive paint is used as the conductive material for forming the conductive trace 202, and the resistance value of the conductive trace 202 can be accurately controlled through processes such as screen printing, so as to accurately regulate the heating power.

[0052] The nano-conductive material ink, such as carbon nanotubes and graphene, has better performance, and specific electrothermal performance can be obtained.

[0053] The planar heating structure provided in the embodiments of the present application is integrated into the target region 101 of the heated component 201, and the formed assembly has both the structural function of the heated component 201 itself and the self-heating function. The planar heating structure provided in the embodiments of the present application is directly “grown” on the target region 101 of the heated component 201 through a multi-layer coating process to form a heating functional coating, which fundamentally eliminates the physical interface and adhesive, and realizes a highly uniform, ultra-reliable and perfectly compatible heating performance in a vacuum environment. There is no physical interface similar to the adhesive layer between the conductive trace 202 and the heated component 201 to match the thermal expansion coefficient, which ensures that it can withstand severe temperature cycle impact and improves its reliability in long-term deep cryogenic environment work. It can be widely used in all components that need to be heated in a low-temperature vacuum environment, such as refrigeration machine associated components, low-temperature sample tables, low-temperature optical elements and adsorption pumps, etc.

[0054] The same heated component 201 can have different target regions 101, and the planar heating structure provided in the embodiments can be integrated into different target regions 101, so as to individually and accurately control the temperature of different target regions 101 of the same heated component 201.

[0055] On the other hand, the present application also provides a preparation method of the planar heating structure for preparing the planar heating structure provided in any of the above embodiments on the heated component 201. The preparation method of the planar heating structure described below can be mutually referred to the planar heating structure described above.

[0056] When the heated component 201 is made of insulating material, the method for manufacturing the planar heating structure provided by the embodiment of the present application comprises steps 110-150.

[0057] Step 110: Pre-treatment is performed on the target area of the heated component, which includes surface roughening treatment and surface cleaning treatment.

[0058] The target area 101 of the heated component 201 is mainly subjected to mechanical polishing and chemical cleaning, so that the target area 101 becomes clean and rough. By increasing the micro-roughness of the target area 101 of the heated component 201, the adhesion area and bonding strength of the subsequent coating to the target area 101 can be enhanced, ensuring that the planar heating structure can still be firmly attached under repeated low-temperature heating and cooling cycle thermal shock.

[0059] Step 120: A conductive material is printed on the target area of the heated component by a screen printing process to form a conductive trace, until the resistance value of the conductive trace reaches a preset resistance value.

[0060] The screen printing process can accurately control the geometric shape and distribution density of the conductive trace 202, ensuring that the heating power is uniformly distributed in the target area 101. By precisely controlling the screen printing process, monitoring and repeating the printing until the preset resistance value is reached, the final rated power of the planar heating structure can be accurately controlled and excellent batch consistency can be achieved.

[0061] Step 130: After the conductive material is solidified, conductive leads are bonded and fixed at both ends of the conductive trace using conductive adhesive, and the conductive adhesive is solidified.

[0062] The use of conductive adhesive for connection can form a low-resistance, high-mechanical-strength electrical connection point 203, ensuring that the current of the external power source 301 can be efficiently and stably transmitted to the conductive trace 202, and ensuring the reliable realization of the heating function.

[0063] Step 140: An insulating material is applied to all exposed surfaces of the conductive trace and the conductive adhesive.

[0064] The layer of insulating material is used to form a surface insulating layer 104, which encapsulates and covers the conductive trace 202 and the electrical connection point 203, provides comprehensive electrical insulation to prevent short circuit or electric shock risk, and also has excellent physical protection effect, protecting the internal circuit from scratches or environmental corrosion, significantly enhancing the durability and safety of the entire planar heating structure.

[0065] Step 150: Baking and curing are performed in a vacuum environment.

[0066] All residual solvents, moisture and other small molecular volatile substances possibly existing in the coating are completely removed at high temperature, effectively reducing the outgassing effect of the planar heating structure in a vacuum working environment, ensuring the cleanliness of the ultra-high vacuum system, and enabling it to perfectly compatible with application fields such as deep cooling physics, space technology and semiconductor process which have strict requirements on vacuum environment.

[0067] The derivation process of the beneficial effects of the preparation method of the planar heating structure in the embodiment of the present application is similar to the derivation process of the beneficial effects of the planar heating structure described above, and thus is not described here.

[0068] In some embodiments, the heated component 201 is made of conductive material. Before step 120, an insulating material can be applied to the target area 101 of the heated component 201, and baking and curing can be performed to form a bottom insulating layer 102. The bottom insulating layer 102 can prevent short circuit between the conductive trace 202 and the heated component 201.

[0069] When the bottom insulating layer 102 is formed on the target area 101 of the heated component 201, a special low-temperature insulating varnish or low-temperature epoxy resin can be uniformly applied to the target area 101 by spraying, brushing or other methods. This ensures the insulating performance while ensuring the heat conduction performance, so that the heat generated by the conductive trace 202 can be effectively transferred to the heated component 201.

[0070] The following takes a 50K radiation shield in a dilution refrigerator as an example to specifically describe the preparation method of the planar heating structure provided by the embodiment of the present application. The radiation shield is made of oxygen-free copper and belongs to conductive material. The planar heating structure is prepared on the radiation shield and is mainly used for temperature control during system operation.

[0071] First, the radiation shield is pretreated to purify the surface of the radiation shield and increase the surface roughness of the radiation shield, so that the subsequent functional coating can be firmly and stably attached to the radiation shield, ensuring the long-term reliability of the entire planar heating structure.

[0072] Specifically, the radiation shield is first placed in a sandblasting machine and uniformly sandblasted with 80-120 mesh aluminum oxide sand to remove the oxide layer and dirt on the surface of the radiation shield and form a micro-rough structure to increase the adhesion area of the coating.

[0073] After sandblasting, the radiation shield is immersed in high-purity isopropyl alcohol in an ultrasonic cleaning tank for at least 20 minutes to completely strip and flush away the oil stains, metal dust and impurities remaining on the surface of the radiation shield by using the cavitation effect of ultrasonic waves.

[0074] After ultrasonic cleaning, the surface of the radiation shield is thoroughly purged with high-purity nitrogen gas with a purity of 99.999% to ensure that there is no liquid residue.

[0075] To ensure that all subsequent steps are carried out in a clean environment, the operator must wear a lint-free glove to prevent fingerprints and other contaminants from causing secondary pollution to the treated surface.

[0076] Second, a bottom insulating layer 102 is prepared on the surface of the radiation shield, and a solid and reliable electrical isolation layer is constructed between the conductive oxygen-free copper of the radiation shield and the subsequent conductive trace 202.

[0077] Specifically, a low-temperature insulating varnish with a model number of GE 7031 is selected as the insulating material, which is mixed with a special diluent according to a mass ratio of 5:1, and is fully stirred with a stirrer until a uniform liquid without sediment is formed, so that its viscosity is suitable for electrostatic spraying process.

[0078] First, the pretreated radiation shield is used as a working electrode and grounded, and then the prepared insulating paint is uniformly sprayed on the surface of the radiation shield by electrostatic spraying process. The thickness of the coating can be accurately controlled by controlling the spraying time and spraying distance, and the thickness of the bottom insulating layer 102 can be controlled within the range of 20-30 microns.

[0079] After spraying, the radiation shield is placed in a program-controlled temperature oven and heated and cured according to the preset program. For example, slowly heat to 100 degrees Celsius at a rate of 2 degrees Celsius per minute, and keep warm for two hours, and finally naturally cool to room temperature with the oven. During the heating and curing process, the coating is completely cross-linked to form a dense and solid insulating film.

[0080] Third, the conductive trace 202 is prepared on the bottom insulating layer 102, and the conductive trace 202 as the core functional layer can efficiently convert electrical energy into uniform heat energy.

[0081] Specifically, a hollow structure with a target geometric size is pre-set on a 200-mesh polyester screen, and a graphite-based conductive paint is accurately printed on the solidified bottom insulating layer 102 using a semi-automatic screen printing technology to form a conductive trace 202 with a shape that meets the pre-design requirements.

[0082] After printing, pre-drying is performed, and then the resistance value between the two ends of the conductive trace 202 is measured. The measured value is compared with the preset resistance value. In this embodiment, the preset resistance value is 50 ohms (symbol Ω). If the measured value is larger than the preset resistance value, one or more times of overprinting is repeated until the measured value enters the range of (50Ω±5%), and the control of the final heating power is realized by accurately controlling the resistance value.

[0083] At both ends of the conductive trace 202, a proper amount of two-component conductive silver epoxy is dispensed as the electrical connection point 203 by a precision dispensing equipment. Subsequently, the core of the pre-processed 30 AWG (AWG is the abbreviation of American Wire Gauge, which is a standard gauge system for representing the diameter and cross-sectional area of circular wires. In the AWG standard, the larger the number, the thinner the wire. 30 AWG represents a very thin wire) manganese copper lead is completely immersed in the conductive silver epoxy.

[0084] The entire anti-radiation screen and manganese copper lead is heated at 120 degrees Celsius for 1 hour to completely cure the conductive silver epoxy, thereby forming a low-resistance, high-strength electrical connection point 203.

[0085] Fourth, the surface insulation layer 104 is prepared outside the conductive trace 202 and is finally cured, aiming to provide all-round encapsulation protection for the conductive trace 202 and to perform thorough vacuum degassing to ensure that the planar heating structure formed meets the requirements of the ultra-high vacuum environment.

[0086] Specifically, the same electrostatic spraying process as that for the bottom insulation layer 102 is adopted, and the GE 7031 insulation varnish is uniformly sprayed outside the conductive trace 202 again, ensuring that the conductive trace 202 and the electrical connection point 203 are completely and pinhole-free covered.

[0087] The sprayed anti-radiation screen is moved into a high-vacuum oven, and the system vacuum degree is pumped to 10 -4 Pascal. Then the heating program is started to rise to 150 degrees Celsius at an extremely slow rate of 1 degree Celsius per minute, and then baking is maintained at this temperature and vacuum degree for 8 hours. On the one hand, it can completely cure the surface insulation varnish, and on the other hand, it can completely remove all residual solvents, moisture and other small molecular volatile substances that may exist in the coating, and complete the final vacuum degassing.

[0088] Fifth, the planar heating structure prepared is subjected to quality detection to verify whether the planar heating structure integrated in the anti-radiation screen meets the design requirements.

[0089] Specifically, after the anti-radiation screen and its planar heating structure are completely cooled to room temperature, the resistance between the two manganese copper leads is measured again using a high-precision micro-ohmmeter to confirm whether the resistance value is still within the range of (50Ω±5%).

[0090] A direct current voltage of 500 volts is applied between any one of the manganese copper leads and the oxygen-free copper of the anti-radiation screen, and then a high resistance meter is used to test the insulation resistance between the two, ensuring that the resistance value is greater than 1 Giga Ohm (symbol: GΩ) to ensure that there is no risk of electric leakage in subsequent experiments.

[0091] Visually inspect all coating surfaces to ensure that they are smooth and even, free of bubbles, cracks, peeling and other defects.

[0092] After all the above tests, the radiation protection screen integrated with the planar heating structure is confirmed as a qualified product, can be finally assembled, and can be connected with the controllable power supply in the low-temperature system, and then put into use.

[0093] It should be emphasized that in the embodiments of the present application, a low-temperature insulating varnish with a model number of GE 7031 is used as the insulating material, which is a special material in the field of low-temperature physics and still maintains excellent toughness at extremely low temperatures without becoming brittle. Moreover, the planar heating structure in the present application as a whole belongs to a micron-level film, and according to the principle of film mechanics, the thermal stress accumulated in the thickness direction of the extremely thin coating is extremely small. In addition, through sandblasting treatment, the surface of the target area 101 of the heated component 201 forms a micro-rough structure, and after the liquid paint penetrates and solidifies, a strong mechanical interlocking effect is formed, which has a physical anchoring effect. The above three safeguards are coupled, so that the planar heating structure can withstand repeated deep low-temperature cold and hot impact without cracking or falling off.

[0094] In another aspect, the embodiments of the present application also provide a low-temperature device, which comprises the planar heating structure provided by any of the above embodiments, and the planar heating structure is coated and solidified on the surface of a heated component of the low-temperature device. The planar heating structure provided by any of the above embodiments has strong adaptability to the heated component with a complex shape, so the low-temperature device provided by the present embodiment has excellent structural reliability and temperature control precision. The derivation process of the beneficial effects of the low-temperature device in the embodiments of the present application is similar to that of the planar heating structure, so it is not repeated here.

[0095] The above low-temperature device is a device capable of working in a low-temperature environment, which can be but is not limited to a refrigeration machine associated component, a low-temperature sample table, a low-temperature optical element, and a sorption pump, etc.

[0096] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A planar heating structure, characterized in that, include: The resistance heating layer includes a conductive trace (202), which is coated and cured with a conductive material in the target area (101) of the heated component (201). The conductive trace (202) is electrically insulated from the heated component (201), and the two ends of the conductive trace (202) are used to connect to an external power supply (301). The surface insulating layer (104) is coated and cured with insulating material on the outside of the conductive trace (202).

2. The planar heating structure according to claim 1, characterized in that, Also includes: The bottom insulating layer (102) is coated and cured with insulating material on the target area (101) of the heated component (201), and the conductive trace (202) is formed on the surface of the bottom insulating layer (102).

3. The planar heating structure according to claim 1, characterized in that, The conductive traces (202) have a consistent distribution density within the target region (101); The conductive trace (202) is formed by multiple spaced trace segments (2021) arranged back and forth and connected alternately at the ends. Each trace segment (2021) has a periodic wavy profile. The wavy profiles of multiple trace segments (2021) are arranged in phase. The spacing between any two adjacent trace segments (2021) is equal.

4. The planar heating structure according to claim 3, characterized in that, The conductive trace (202) is formed by screen printing.

5. The planar heating structure according to claim 1, characterized in that, Also includes: A conductive lead (302) is provided, with one conductive lead (302) corresponding to each end of the conductive trace (202). The conductive lead (302) is electrically connected to the end of the conductive trace (202), and the conductive lead (302) is used to connect to the external power supply (301).

6. The planar heating structure according to claim 5, characterized in that, The conductive lead (302) is fixed to the end of the conductive trace (202) by conductive adhesive.

7. The planar heating structure according to claim 5, characterized in that, The insulating material includes one of low-temperature insulating varnish and low-temperature epoxy resin; And / or, the conductive material includes one of graphite-based conductive paint and nano-conductive material ink; And / or, the conductive lead (302) is made of manganese copper alloy.

8. A cryogenic device, characterized in that, Includes the planar heating structure as described in any one of claims 1 to 7.

9. A method for preparing a planar heating structure, characterized in that, A method for fabricating a planar heating structure as described in any one of claims 1 to 7 on a heated component, the method comprising: The target area of ​​the heated component is pretreated, and the pretreatment includes surface roughening treatment and surface cleaning treatment. Conductive material is printed in the target area of ​​the heated component using a screen printing process to form conductive traces until the resistance value of the conductive traces reaches a preset resistance value. After the conductive material is cured, conductive leads are bonded and fixed at both ends of the conductive trace using conductive adhesive, and the conductive adhesive is then cured. Apply an insulating material to all exposed surfaces of the conductive traces and the conductive adhesive; Baking and curing are carried out in a vacuum environment.

10. The method for preparing the planar heating structure according to claim 9, characterized in that, Before printing conductive material in the target area of ​​the heated component, the method further includes: An insulating material is applied to the target area of ​​the heated component, and then baked and cured.

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