Nickel-based thin-wall cold shield of refrigeration type infrared detector enhanced by surface multilayer composite coating material and preparation method thereof

Abstract

The present application relates to surface multilayer composite coating material reinforced heat conduction refrigeration type infrared detector Dewar nickel-based thin-wall cold shield and its preparation method, belong to refrigeration type infrared detector technical field. The method is that the nickel-based thin-wall cold shield with blackened inner surface is loaded into electron beam evaporation coating fixture; the electron beam evaporation coating equipment is pumped to high vacuum; when the vacuum degree of the electron beam evaporation coating equipment is greater than 1x10 ‑3 Pa, the surface of the thin-wall cold shield to be plated is baked at 200 DEG C; when the vacuum degree of the electron beam evaporation coating equipment is greater than 5x10 ‑4 Pa, the cold shield is cleaned by argon plasma; the nickel adhesion layer, copper heat conduction layer and silver heat conduction layer are plated on the surface of the cold shield in sequence; the present application does not significantly increase the heat mass of Dewar cold head on the basis of keeping the mechanical properties and thermodynamic properties of nickel-based thin-wall cold shield unchanged, can significantly enhance the heat conduction performance of the cold shield, speed up the heat transfer, and realize the rapid start of refrigeration type infrared detector.

Description

Technical Field

[0001] This invention belongs to the field of cooled infrared detector technology, specifically relating to a Dewar nickel-based thin-walled cold screen for cooled infrared detectors with enhanced thermal conductivity through a multi-layer composite coating material on the surface, and its preparation method. Background Technology

[0002] Cooled infrared focal plane detector (FFP) Dewar products are vacuum-insulated devices used for the vacuum packaging of infrared detector chips. Coupled with a cooler, they form an infrared FFP detector assembly. Dewar not only provides a suitable low-temperature operating environment for the detector chip but also provides optical, mechanical, and electrical interfaces, making it one of the core components of the FFP assembly. The Dewar cold head structure is a crucial part of the Dewar product, providing low-stress mechanical support for thermal expansion matching of the chip, and also serving as a heat coupling channel between the detector chip and the cooler's cold fingers. A typical Dewar cold head includes a ceramic substrate, detector chip, thin-walled metal cold shield, and filters. In rapidly cooled infrared FFP detector assemblies, the Dewar cold head structure and the properties of the materials used directly determine the cooling time.

[0003] For a given Dewar cold head structure with a fixed thermal mass, the amount of heat that needs to be extracted when the temperature drops from room temperature t0 (~300K) to operating temperature t1 (~77K) can be expressed as:

[0004]

[0005] Where Q represents heat; m n For the quality of the material; c n Δt = t0 - t1 is the specific heat capacity of the material; Δt = t0 - t1 is the operating temperature difference of the detector; n is a positive integer representing the types of materials contained in the cold head structure.

[0006] Typically, for a given Dewar cold head structure and material, the cold shield is the primary heat source during the cooling process. The material used to fabricate the cold shield is usually a nickel-based alloy; nickel and its alloys are widely used in Dewar cold shields due to their excellent mechanical properties and ease of fabrication. However, nickel has a thermal conductivity of approximately ~70 W / (m·K). This low thermal conductivity results in a slow cooling rate of the cold shield during the detector's cooling process, thus affecting the overall cooling time of the detector product.

[0007] In summary, the thermal conductivity of the cold screen made of nickel and its alloys in the rapid-cooling infrared focal plane detector is affected by the low thermal conductivity of the material, and it is difficult to improve the thermal conductivity of the cold screen by structural design alone. That is, the disadvantage of traditional single-layer thin-walled cold screens made of nickel and its alloys is that, due to the low thermal conductivity of the material, the cooling rate of the detector components is slow, which seriously affects the rapid cooling start-up of the cooled infrared focal plane detector.

[0008] Therefore, overcoming the shortcomings of existing technologies is an urgent problem to be solved in the field of cooled infrared detector technology. Summary of the Invention

[0009] The purpose of this invention is to solve the problems of low thermal conductivity and slow cooling speed of single-layer structure materials in the Dewar nickel-based thin-walled cold shield of cooled infrared focal plane detectors. It provides a Dewar nickel-based thin-walled cold shield for cooled infrared detectors with enhanced thermal conductivity through a multi-layer composite coating material on the surface, as well as its preparation method. This improves the thermal conductivity of the Dewar nickel-based thin-walled cold shield, ensures rapid cooling of the cold head, and enhances the rapid start-up performance of cooled infrared focal plane detector products.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material includes the following steps:

[0012] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0013] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0014] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0015] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0016] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0017] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm to 1 μm.

[0018] The copper thermal conductive layer is made of metallic copper and has a thickness of 5μm to 50μm.

[0019] The silver thermal conductive layer is made of metallic silver and has a thickness of 5μm to 50μm.

[0020] Furthermore, preferably, in step one, the thickness of the nickel-based thin-walled cold shield is 0.08 mm to 0.30 mm.

[0021] Furthermore, preferably, the baking time in step three is 10 minutes.

[0022] Furthermore, preferably, in step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0023] Furthermore, preferably, in step five, a 0.5μm thick nickel adhesion layer, a 5μm thick copper thermal conductive layer, and a 5μm thick silver thermal conductive layer are sequentially deposited on the surface of the cold screen.

[0024] Furthermore, preferably, in step five, the total thickness of the copper thermal conductive layer and the silver thermal conductive layer is 9.5% to 10.5% of the thickness of the nickel-based thin-walled cold screen.

[0025] The present invention provides a method for preparing a Dewar nickel-based thin-walled cold shield for a cooled infrared detector with enhanced thermal conductivity using a multi-layer composite coating material on the surface.

[0026] This invention enables thin-walled cold shields to overcome the limitations of low thermal conductivity in nickel-based materials, and functionally achieve high thermal conductivity, thereby improving the cooling rate of Dewar cold heads.

[0027] The multilayer composite coating material structure of this invention has a material system of nickel / copper / silver (Ni / Cu / Ag). Except for the nickel layer, silver (~430 W / (m·K)) and copper (~400 W / (m·K)) both have better thermal conductivity than nickel (~70 W / (m·K)). The multilayer composite coating material includes an adhesion layer and a thermally conductive enhancement layer. The nickel layer serves as the adhesion layer to ensure reliable bonding to the surface of the nickel-based thin-walled cold shield. The thermally conductive enhancement layer comprises high thermal conductivity metal layers of silver and copper. A copper thermally conductive layer is used as a transition between the nickel adhesion layer and the silver thermally conductive layer to prevent poor adhesion due to the low miscibility between nickel and silver. The surface emissivity of silver is lower than that of nickel, which reduces the emissivity of the outer surface of the cold shield, further reducing radiative heat leakage.

[0028] The present invention provides a Dewar nickel-based thin-walled cold shield for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material. While maintaining the high reliability of the mechanical properties of traditional nickel-based thin-walled cold shields, the invention significantly enhances the thermal conductivity of the cold shield without significantly increasing the thermal mass of the Dewar cold head.

[0029] This invention allows for flexible adjustment of the thickness ratio between the nickel-based thin-walled cold screen and the multi-layer composite coating material on its surface, based on the detector's cooling rate requirements, thus obtaining the cooling rate requirements for different application scenarios. A preferred parameter is that the total thickness of the copper and silver thermally conductive layers is 10% of the thickness of the nickel-based thin-walled cold screen. At this value, the thermal conductivity of the enhanced nickel-based thin-walled cold screen is significantly increased, without a significant change in its thermal mass.

[0030] In this invention, the outermost metal of the multilayer composite coating material is silver. Silver has lower loss than nickel in the infrared band, thereby achieving higher reflectivity and reducing the radiative heat leakage of the Dewar.

[0031] The preparation method of this invention can select physical vapor deposition technology such as electron beam evaporation coating equipment, which is highly feasible and suitable for mass production.

[0032] Compared with the prior art, the beneficial effects of this invention are as follows:

[0033] This invention avoids the limitations of traditional nickel-based thin-walled cold shield designs that rely on a single material and thus struggle to simultaneously achieve optimal mechanical and thermal properties. It employs a multi-layered composite surface coating material to enhance the thermal conductivity of the nickel-based thin-walled cold shield, enabling it to possess both highly reliable mechanical properties and excellent thermal conductivity. Since silver and copper in the enhanced thermal conductivity layer have thermal conductivity several times higher than nickel, a few micrometers thick enhanced thermal conductivity layer is sufficient to significantly improve the thermal conductivity of the cold shield without a significant increase in the overall thermal mass. The nickel-based thin-walled cold shield with the multi-layered composite surface coating material readily meets the requirements of highly reliable mechanical support and rapid cooling in cooled infrared detectors.

[0034] This invention significantly enhances the thermal conductivity of the cold shield without significantly increasing the thermal mass of the Dewar cold head, while maintaining the mechanical and thermodynamic properties of the nickel-based thin-walled cold shield and accelerating heat transfer, thus enabling rapid startup of the cooled infrared detector.

[0035] The preparation process of this invention is simple. It can be completed by physical vapor deposition using conventional electron beam evaporation coating equipment, etc. The process is mature and highly operable.

[0036] The outermost layer of the multilayer composite coating material of this invention is silver, which can improve the reflective properties of the outer surface of the cold screen, reduce radiative heat transfer between the cold screen and the Dewar shell, reduce heat leakage of the Dewar cold head, and reduce the power required by the refrigeration unit. Attached Figure Description

[0037] Figure 1 This is a structural diagram of a conventional cooling-type Dewar nickel-based thin-walled cold shield;

[0038] Figure 2 This is a schematic diagram of the structure of the Dewar nickel-based thin-walled cold shield for a cooled infrared detector, which uses a multi-layer composite coating material to enhance thermal conductivity.

[0039] Figure 3 A schematic diagram of the layered structure of the Dewar nickel-based thin-walled cold shield for a cooled infrared detector, which enhances thermal conductivity with a multi-layer composite coating material on the surface, according to the present invention.

[0040] Figure 4The cooling simulation curve of the Dewar nickel-based thin-walled cold screen for a cooled infrared detector, which uses a multi-layer composite coating material to enhance thermal conductivity according to the present invention;

[0041] In the figure, 1-nickel-based thin-walled cold screen, 2-black coating of cold screen, 3-multi-layer composite coating material on the surface, 4-nickel adhesion layer, 5-copper thermal conductive layer, 6-silver thermal conductive layer. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the embodiments.

[0043] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the field or according to the product instructions. Materials or equipment whose manufacturers are not specified are all conventional products that can be obtained by purchase.

[0044] Example 1

[0045] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0046] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0047] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0048] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0049] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0050] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0051] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.8 μm;

[0052] The copper thermal conductive layer is made of metallic copper and has a thickness of 20μm.

[0053] The silver thermal conductive layer is made of metallic silver and has a thickness of 10μm.

[0054] Example 2

[0055] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0056] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0057] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0058] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0059] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0060] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0061] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm;

[0062] The copper thermal conductive layer is made of metallic copper and has a thickness of 5μm.

[0063] The silver thermal conductive layer is made of metallic silver and has a thickness of 5μm.

[0064] In step one, the thickness of the nickel-based thin-walled cold shield is 0.08 mm.

[0065] In step three, the baking time is 10 minutes.

[0066] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0067] Example 3

[0068] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0069] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0070] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0071] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0072] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0073] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0074] The nickel adhesion layer is made of metallic nickel and has a thickness of 1 μm;

[0075] The copper thermal conductive layer is made of metallic copper and has a thickness of 50μm.

[0076] The silver thermal conductive layer is made of metallic silver and has a thickness of 50μm.

[0077] In step one, the thickness of the nickel-based thin-walled cold shield is 0.30 mm.

[0078] In step three, the baking time is 10 minutes.

[0079] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0080] Example 4

[0081] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0082] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0083] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0084] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0085] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0086] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0087] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.5 μm;

[0088] The copper thermal conductive layer is made of metallic copper and has a thickness of 25μm.

[0089] The silver thermal conductive layer is made of metallic silver and has a thickness of 25μm.

[0090] In step one, the thickness of the nickel-based thin-walled cold shield is 0.25 mm.

[0091] In step three, the baking time is 10 minutes.

[0092] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0093] Example 5

[0094] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0095] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0096] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0097] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0098] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0099] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0100] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.5 μm;

[0101] The copper thermal conductive layer is made of metallic copper and has a thickness of 5μm.

[0102] The silver thermal conductive layer is made of metallic silver and has a thickness of 5μm.

[0103] In step one, the thickness of the nickel-based thin-walled cold shield is 0.2 mm.

[0104] In step three, the baking time is 10 minutes.

[0105] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0106] Example 6

[0107] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0108] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0109] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0110] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0111] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0112] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0113] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm;

[0114] The copper thermal conductive layer is made of metallic copper and has a thickness of 5μm.

[0115] The silver thermal conductive layer is made of metallic silver and has a thickness of 5μm.

[0116] In step one, the thickness of the nickel-based thin-walled cold shield is 0.095 mm.

[0117] In step three, the baking time is 10 minutes.

[0118] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0119] The total thickness of the copper and silver thermal conductive layers is 9.5% of the thickness of the nickel-based thin-walled cold shield.

[0120] Example 7

[0121] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0122] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0123] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0124] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0125] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0126] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0127] The nickel adhesion layer is made of metallic nickel and has a thickness of 1 μm;

[0128] The copper thermal conductive layer is made of metallic copper and has a thickness of 10μm.

[0129] The silver thermal conductive layer is made of metallic silver and has a thickness of 10μm.

[0130] In step one, the thickness of the nickel-based thin-walled cold shield is 0.21 mm.

[0131] In step three, the baking time is 10 minutes.

[0132] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0133] The total thickness of the copper and silver thermal conductive layers is 10.5% of the thickness of the nickel-based thin-walled cold shield.

[0134] Example 8

[0135] A method for fabricating a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material is characterized by comprising the following steps:

[0136] Step 1: Place the nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0137] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0138] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 At Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃;

[0139] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0140] Step 5: Sequentially deposit a nickel adhesion layer, a copper thermal conductive layer, and a silver thermal conductive layer on the surface of the cold screen;

[0141] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.5 μm;

[0142] The copper thermal conductive layer is made of metallic copper and has a thickness of 5μm.

[0143] The silver thermal conductive layer is made of metallic silver and has a thickness of 5μm.

[0144] In step one, the thickness of the nickel-based thin-walled cold shield is 0.10 mm.

[0145] In step three, the baking time is 10 minutes.

[0146] In step four, when using argon plasma cleaning, the cleaning time is 300 seconds.

[0147] The total thickness of the copper and silver thermal conductive layers is 10% of the thickness of the nickel-based thin-walled cold shield.

[0148] Application Examples

[0149] like Figure 2 and Figure 3 As shown, a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity using a multi-layer composite coating material is described. The cold screen comprises: a nickel-based thin-walled cold screen 1, a cold screen blackening coating 2, and a multi-layer composite coating material 3. The multi-layer composite coating material 3 includes: a nickel adhesion layer 4, a copper thermally conductive layer (5), and a silver thermally conductive layer 6.

[0150] Preparation steps of surface multilayer composite coating material 3:

[0151] Step 1: Place the 0.1mm thick nickel-based thin-walled cold screen, whose inner surface has been blackened, into the electron beam evaporation coating fixture;

[0152] Step 2: Evacuate the electron beam evaporation coating equipment to a high vacuum;

[0153] Step 3: The vacuum degree of the electron beam evaporation coating equipment must be greater than 1×10⁻⁶. -3 When Pa, the surface of the thin-walled cold screen to be plated is baked at 200℃ for 10 minutes.

[0154] Step 4: The vacuum degree of the electron beam evaporation coating equipment must be greater than 5×10⁻⁶. -4 At Pa, the cold screen is subjected to argon plasma cleaning for 300 seconds;

[0155] Step 5: Sequentially deposit a 0.5μm thick nickel coating layer, a 5μm thick copper thermal conductive layer, and a 5μm thick silver thermal conductive layer on the surface of the cold screen.

[0156] The simulation analysis of the cooling process of the nickel-based thin-walled cold shield with enhanced thermal conductivity through the aforementioned multi-layer composite coating material is shown below. Figure 4As shown in the figure. For a cold screen structure with a length l = 5 mm, a boundary condition of -200 °C is applied at end A, and the room temperature of 22 °C is applied at end B, with a cooling time of 1 s. Without the use of a multi-layer composite coating material to enhance thermal conductivity, the cooling rate of the nickel-based thin-walled cold screen is 151 °C / s, while the cooling rate of the nickel-based thin-walled cold screen with the multi-layer composite coating material to enhance thermal conductivity is 213 °C / s. The total thickness of the copper and silver thermal conductive layers is 10 μm, which is only 10% of the thickness of the 0.1 mm nickel-based thin-walled cold screen, yet the cooling rate is increased by 41%, indicating that the cooling rate of the nickel-based thin-walled cold screen is significantly improved after using a multi-layer composite coating material to enhance thermal conductivity.

[0157] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a refrigeration-type infrared detector dewar nickel-based thin-wall cold shield with surface multilayer composite coating material enhanced thermal conductivity, characterized in that, It comprises the following steps: Step one: put the nickel-based thin-wall cold shield with blackened inner surface into the electron beam evaporation coating fixture; Step two: draw high vacuum on the electron beam evaporation coating equipment; Step three: when the vacuum degree of the electron beam evaporation coating equipment is greater than 1x10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C; Step four: when the vacuum degree of the electron beam evaporation coating equipment is greater than 5*10 -4 Pa, the cold screen is subjected to 300s argon plasma cleaning treatment; Step five: successively coat nickel adhesion layer, copper heat conduction layer and silver heat conduction layer on the surface of the cold shield; The nickel adhesion layer is made of metal nickel and has a thickness of 0.1-1 μm; The copper heat conduction layer is made of metal copper and has a thickness of 5-50 μm; The silver heat conduction layer is made of metal silver and has a thickness of 5-50 μm.

2. The method of claim 1, wherein the method is for preparing a nickel-based thin-walled cold shield for a cryogenically cooled infrared detector, the cold shield comprising a surface multi-layer composite coating material for enhancing thermal conductivity, the method comprising: depositing a first layer of a first material on a substrate; depositing a second layer of a second material on the first layer; and depositing a third layer of a third material on the second layer, wherein the first material, the second material, and the third material are different materials. In step one, the thickness of the nickel-based thin-wall cold shield is 0.08-0.30 mm.

3. The method of claim 1, wherein the method is for preparing a nickel-based thin-walled cold shield for a cryogenically cooled infrared detector, the cold shield comprising a surface multi-layer composite coating material for enhancing thermal conductivity, the method comprising: depositing a first layer of a first material on a substrate; depositing a second layer of a second material on the first layer; and depositing a third layer of a third material on the second layer, wherein the first material, the second material, and the third material are different materials. In step three, the baking time is 10 min.

4. The method of claim 1, wherein the method is for preparing a nickel-based thin-walled cold shield for a cryogenically cooled infrared detector, the cold shield comprising a surface multi-layer composite coating material for enhancing thermal conductivity, the method comprising: depositing a first layer of a first material on a substrate; depositing a second layer of a second material on the first layer; and depositing a third layer of a third material on the second layer, wherein the first material, the second material, and the third material are different materials. In step four, when argon plasma cleaning is used, the cleaning time is 300 s.

5. The method for preparing a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity using a multi-layer composite coating material on the surface, as described in claim 1, is characterized in that... In step five, 0.5-μm-thick nickel adhesion layer, 5-μm-thick copper heat conduction layer and 5-μm-thick silver heat conduction layer are successively coated on the surface of the cold shield.

6. The method for preparing a Dewar nickel-based thin-walled cold screen for a cooled infrared detector with enhanced thermal conductivity through a multi-layer composite coating material as described in claim 1, characterized in that... In step five, the total thickness of the copper heat conduction layer and the silver heat conduction layer is 9.5-10.5% of the thickness of the nickel-based thin-wall cold shield.

7. The nickel-based thin-wall cold shield of a refrigeration-type infrared detector with surface multi-layer composite coating material enhanced heat conduction prepared by the method of any one of claims 1-6.

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