Dewar cold table, preparation method thereof and refrigeration infrared detector

Abstract

The invention provides a Dewar cold table and a preparation method thereof and a refrigeration infrared detector, and relates to the technical field of infrared detectors, the Dewar cold table comprises a cold table body, a plurality of bosses are distributed on the upper surface and / or the lower surface of the cold table body, and the bosses are inverted cones. The Dewar cold table has the beneficial effects that the boss in the shape of the inverted cone is formed on the surface of the cold table body, so that the surface area of the Dewar cold table is effectively increased, the heat conduction efficiency is improved, meanwhile, glue has more adsorption sites, and the bonding strength is effectively enhanced; due to the arrangement of the boss, the surface of the cooling table body is roughened, so that before the cooling table body and glue with the surface infiltrated and solidified generate relative displacement, the glue and the inverted cone generate an interlocking effect, and relative movement of an interface is hindered; and due to the shape of the inverted cone, the glue in a fluid state can easily enter a groove structure formed between the adjacent inverted cones, so that once the glue is solidified, a riveting structure is formed between the glue and the boss, and the bonding strength is further enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of infrared detectors, and in particular to a Dewar cooling stage and a preparation method thereof, and a refrigerated infrared detector. Background Art

[0002] Rapid cooling of infrared detectors has always been a key development direction of the industry. At present, rapid cooling is mainly achieved by reducing the thermal mass of the cold head (including: reducing the thickness of the cold stage to 0.1-0.2mm, reducing the thickness of the substrate to 0.4-0.6mm, reducing the diameter of the cold head, etc.), increasing the power of the refrigerator, and gold-plating the cold head to reduce the radiation absorption rate. The rapid cooling direction has reached a bottleneck.

[0003] The surface of the existing Dewar cold table is usually not specially treated, and in order to make its upper and lower surfaces flat, the cold table surface is often processed to be relatively smooth, which is not conducive to the glue on the cold head to adhere to the cold table. At present, the gain effect of reducing the mass of the cold head and changing the glue material on the cold head bonding strength has reached its limit. At a temperature of around 77K, due to the difference in thermal expansion coefficients between glue and metal and the ductile-brittle transition of the glue, the glue-metal interface is very likely to separate.

[0004] In addition, rapid cooling technology is not limited to the power of the refrigerator; the flat and smooth surface of the cold table means that it only has a very small surface area, which is not conducive to heat exchange between the gas and the cold table; it limits the amount of cold that the refrigerator can deliver to the cold head. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a Dewar cooling stage, comprising a cooling stage body, wherein a plurality of bosses are distributed on the upper surface and / or the lower surface of the cooling stage body, and the bosses are inverted cones.

[0006] Preferably, a plurality of grooves are formed on the surface of the cold stage body and are located between the bosses. The grooves are unidirectional grooves, annular grooves, spiral grooves, or staggered grooves.

[0007] Preferably, the projection of the boss on the surface of the cold stage body is in the shape of a regular hexagon, a triangle, a circle or a rectangle.

[0008] Preferably, the side length of the regular hexagon is 0.1 mm-0.5 mm, and the height of the boss is 0.1 mm-0.5 mm.

[0009] Preferably, at least one step is stacked between the boss and the cold stage body.

[0010] Preferably, the steps in each layer are regular cones, and / or prisms, and / or inverted cones.

[0011] The present invention also provides a method for preparing a Dewar cooling stage, which is used to prepare the above-mentioned Dewar cooling stage, comprising:

[0012] Step A1, using a laser to vertically etch the surface of the cold stage body to form a columnar microstructure;

[0013] Step A2, aligning the focused spot of the laser to the bottom of the columnar microstructure, so as to perform tilted rotation cutting on the columnar microstructure to obtain a Dewar cooling stage with a plurality of bosses distributed on the surface.

[0014] The present invention also provides a method for preparing a Dewar cooling stage, which is used to prepare the above-mentioned Dewar cooling stage, comprising:

[0015] Step B1, using wire cutting to flatten the surface of the cold stage body, and using the flattened surface as a reference surface for cutting processing;

[0016] Step B2, performing wire cutting on the reference surface along a preset direction according to a preset path to obtain an inverted tapered strip groove, and then performing wire cutting on the reference surface along a direction perpendicular to the preset direction according to the preset path to obtain a Dewar cooling table with a plurality of bosses distributed on the surface;

[0017] The preset path is a Z-shape and an inverted Z-shape connected in sequence, and the inverted Z-shape is obtained by mirroring the Z-shape.

[0018] The present invention also provides a method for preparing a Dewar cooling stage, which is used to prepare the above-mentioned Dewar cooling stage, comprising:

[0019] Step C1, using a milling head to perform multi-layer milling on the surface of the cold stage body in a direction perpendicular to the cold stage body to form a columnar microstructure;

[0020] Step C2, tilting the milling head to mill the side of the columnar microstructure to obtain a Dewar cooling table with a plurality of bosses distributed on the surface.

[0021] The present invention also provides a refrigerated infrared detector, comprising the above-mentioned Dewar cooling stage.

[0022] The above technical solution has the following advantages or beneficial effects:

[0023] 1) By forming an inverted cone-shaped boss on the surface of the cooling platform body, the surface area of ​​the Dewar cooling platform is effectively increased, which improves the thermal conductivity and provides more adsorption sites for the glue, effectively enhancing the bonding strength;

[0024] 2) The setting of the boss makes the surface of the cold platform body rough, so that before the relative displacement between the cold platform body and the glue infiltrated and solidified on the surface occurs, the glue and the inverted cone will have an interlocking effect, hindering the relative movement of the interface;

[0025] 3) The shape of the inverted cone allows the glue to easily enter the groove structure formed between adjacent inverted cones when in a fluid state, so that once the glue is cured, it forms a riveted structure with the boss, further enhancing the bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a Dewar cooling stage with bosses distributed on the surface in a preferred embodiment of the present invention;

[0027] Figure 2 It is a side view of a Dewar cooling stage with bosses distributed on the surface in a preferred embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of a staggered arrangement of triangular bosses in a preferred embodiment of the present invention;

[0029] Figure 4 The figure is a side view of a Dewar cooling stage with bosses having steps distributed on the surface in a preferred embodiment of the present invention;

[0030] Figure 5 The figure is a schematic flow chart of a method for preparing a Dewar cooling stage in a preferred embodiment of the present invention;

[0031] Figure 6 The process diagram of the laser rotary cutting method in the preferred embodiment of the present invention;

[0032] Figure 7 The figure is a schematic flow chart of a method for preparing a Dewar cooling stage in a preferred embodiment of the present invention;

[0033] Figure 8 A process diagram of a wire cutting method in a preferred embodiment of the present invention;

[0034] Fig. 9 The figure is a schematic flow chart of a method for preparing a Dewar cooling stage in a preferred embodiment of the present invention;

[0035] Fig.10 A process diagram of a milling method in a preferred embodiment of the present invention;

[0036] Fig.11 In a preferred embodiment of the present invention, the process diagram of a Dewar cooling table having bosses with steps distributed on the surface is processed by combining milling, wire cutting and laser peeling. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment, and other embodiments may also fall within the scope of the present invention as long as they conform to the gist of the present invention.

[0038] In a preferred embodiment of the present invention, based on the above problems existing in the prior art, a Dewar cooling stage is provided. Figure 1 and Figure 2 As shown, it comprises a cold stage body 1, and a plurality of bosses 2 are distributed on the upper surface and / or the lower surface of the cold stage body 1, and the bosses 2 are inverted cones.

[0039] Specifically, the present invention forms a plurality of bosses 2 on the surface of the cold platform body 1 through microstructuring, thereby effectively increasing the surface area of ​​the cold platform body 1 and enhancing the bonding strength and thermal conductivity of the surface of the cold platform body 1. The bosses 2 may be distributed only on the upper surface of the cold platform body 1, or only on the lower surface of the cold platform body 1, or may be formed on both the upper and lower surfaces of the cold platform body 1, which is not limited here and can be flexibly adjusted according to actual needs.

[0040] Furthermore, the microstructure on the surface of the cold platform body 1 is designed to be a boss type, which is more suitable for the fluid to flow between the grooves formed between the bosses 2, thereby enhancing the heat exchange capacity between the bosses 2 and the fluid, where the fluid can be either gas or liquid. Compared with the pit type microstructure, since the pit is a semi-enclosed chamber, fluids with poor fluidity, such as glue, are prone to form air pockets when passing through the pit type microstructure, which not only does not increase the bonding area, but reduces the bonding area, and increases the residual gas inside the vacuum system. Based on this, the boss type microstructure of the present invention solves the above problems well, and can effectively enhance the bonding strength and thermal conductivity of the surface of the cold platform body 1.

[0041] Specifically, when applying glue, you can use a needle to inject glue and let the glue slowly infiltrate under the action of gravity; you can also use rubber tweezers to pull the glue to speed up the infiltration rate. After the infiltration is completed, use a rubber scraper to scrape off the excess glue.

[0042] In a preferred embodiment of the present invention, a plurality of grooves 3 are formed on the surface of the cold stage body 1 and are located between the bosses 2. The grooves 3 are unidirectional grooves, annular grooves, spiral grooves, or staggered grooves.

[0043] In a preferred embodiment of the present invention, the projection of the boss 2 on the surface of the cold stage body 1 is a regular hexagon, a triangle, a circle or a rectangle, wherein the regular hexagon and the triangle are preferably arranged in a staggered manner due to their special shapes to obtain a larger surface area. Figure 1 The circular bosses 2 are arranged in sequence to form a unidirectional groove. Figure 3 The bosses in the middle triangle are also arranged in a staggered manner to form staggered grooves.

[0044] In a preferred embodiment of the present invention, the side length of the regular hexagon is 0.1 mm-0.5 mm, and the height of the boss is 0.1 mm-0.5 mm.

[0045] Specifically, it has been verified through experiments that the hexagonal microstructure with a side length of 0.1 mm-0.5 mm and a height of 0.1 mm-0.5 mm can not only ensure its own structural strength, but also increase the surface area of ​​the cold stage body 1 to 4 times of the original, as shown in the following Table 1:

[0046] Table 1 Relationship between surface area and tensile strength and the height of regular hexagon

[0047] Height of regular hexagon (mm) 0 0.1 0.3 0.5 Area after processing / original area (times) 1 1.6 2.8 4.0 Tensile strength(kg) 40.1 76.4 163.8 217.3

[0048] The increase in surface area can not only provide more adsorption sites for glue, but also roughen the surface of the cold platform body 1. Before the rough surface and the glue infiltrated and solidified on its surface want to have relative displacement, the glue and the microstructure will have an interlocking effect, hindering the relative movement of the interface, thereby improving the bonding strength. As shown in Table 1 above, when the surface area is increased to 4 times the original, the tensile strength can reach 217.3 kg. Compared with the tensile strength of 40.1 kg of the cold platform body with the original metal surface that has not been treated, it can be seen that the tensile strength has increased to 5 times the original.

[0049] Furthermore, the bonding strength is not only related to the surface area, but also to the shape of the microstructure. The inverted cone microstructure is easy to enter its groove structure when the glue is in a fluid state. Once solidified, it forms a riveted structure with the inverted cone microstructure. If you want to separate the glue from the cold table, you not only need to separate the interface between the glue and the cold table, but also need to destroy the glue riveting structure to further improve the bonding strength.

[0050] Furthermore, by etching a boss-type microstructure on the surface of the cold platform body 1, the heat exchange rate of the gas-solid interface is effectively increased. Experimental verification shows that the cooling time can be reduced by 20s to 251s at most, as shown in Table 2 below:

[0051] Table 2 Relationship between surface area and cooling time and the height of the regular hexagon

[0052] Height of regular hexagon (mm) 0 0.1 0.3 0.5 Area after processing / original area (times) 1 1.6 2.8 4.0 Cooling time(s) 271 266 256 251

[0053] In summary, the use of the Dewar cooling stage of the present invention can not only reduce the time required for chip cooling, but also enhance the reliability of the cold head in resisting vibration and impact.

[0054] In a preferred embodiment of the present invention, Figure 4 As shown, at least one layer of steps 4 is stacked between the boss 2 and the cold stage body 1 .

[0055] In a preferred embodiment of the present invention, each layer of steps 4 is a regular cone, and / or a prism, and / or an inverted cone.

[0056] Specifically, in this embodiment, the multiple steps form a nested structure, which can be formed by stacking up and down different shapes of positive cones, prisms, and inverted cones, and the upper structure is often smaller than the lower structure; it can be a multi-level stacking. Figure 4 A schematic diagram of a layer of prismatic steps and bosses 2 stacked together is provided, but the present invention is not limited thereto.

[0057] The present invention also provides a method for preparing a Dewar cooling stage, which is used to prepare the above-mentioned Dewar cooling stage. Figure 5 As shown, it is prepared by laser peeling method, including:

[0058] Step A1, using a laser to vertically etch the surface of the cold stage body to form a columnar microstructure;

[0059] Step A2, aligning the focused spot of the laser to the bottom of the columnar microstructure, so as to perform tilted rotation cutting on the columnar microstructure to obtain a Dewar cooling stage with a plurality of bosses distributed on the surface.

[0060] Specifically, millisecond and nanosecond lasers will produce phase explosions during the processing, resulting in incomplete structure damage and accompanied by an oxide layer of more than 10 microns, which will seriously affect the bonding strength. Therefore, the laser used in this embodiment is preferably a 355-1064nm wavelength, a picosecond or femtosecond laser, a spot diameter of 5-50 microns after focusing, and a power of 1-50W (usually only a laser with a power of 5-20W is sufficient).

[0061] As a preferred embodiment, Figure 6 As shown in (a), the surface of the cold stage body 1 can be etched by an ultrafast laser along the dotted line direction in the figure to obtain a columnar microstructure 5, which includes but is not limited to a cylinder and a prism. The removal depth of a single etching is preferably 0.01-0.1 mm, and low-power multi-layer removal can be performed to achieve the molding of the microstructure, which not only ensures the integrity of the microstructure obtained by etching, but also reduces the thermal effect, so that the oxide layer formed on the surface of the cold stage body after etching is shallower and more uniform, and is easier to remove by strong acid corrosion.

[0062] After etching to obtain the columnar microstructure 5, in order to obtain the boss 2, as shown in FIG. Figure 6 As shown in (b), it is preferred that the laser be tilted by a mechanical arm to hold the laser, and then the focused spot is aligned with the bottom of the microstructure, and etching and cutting are performed from the outside to the inside. A circular inverted cone structure can be obtained by circular cutting; a straight line cutting can also be selected to obtain a triangular, square or hexagonal inverted cone structure. The inverted cone structure can also be achieved by multi-layer cutting.

[0063] After etching to obtain a plurality of bosses, the surface oxide of the cold platform body is corroded with a strong acid, and then cleaned with alcohol and acetone and then vacuum dried to make the surface dry and clean. The strong acid here can be nitric acid, sulfuric acid or aqua regia, and the corrosion time is preferably 20s-10min.

[0064] The laser rotary cutting method in this embodiment can be used to process microstructures of 5-10 microns, with a fast processing speed, a high diversity of structures that can be achieved, and almost no mechanical processing stress on the surface of the cold stage.

[0065] The present invention also provides a method for preparing a Dewar cooling stage, which is used to prepare the above-mentioned Dewar cooling stage. Figure 7 As shown, it is prepared by wire cutting method, including:

[0066] Step B1, using wire cutting to flatten the surface of the cold stage body, and using the flattened surface as a reference surface for cutting processing;

[0067] Step B2, performing wire cutting along a preset direction on a reference surface according to a preset path to obtain an inverted tapered strip groove, and then performing wire cutting along a direction perpendicular to the preset direction on the reference surface according to a preset path to obtain a Dewar cooling table with a plurality of bosses distributed on the surface;

[0068] The preset path is a Z shape and an inverted Z shape connected in sequence, and the inverted Z shape is obtained by mirroring the Z shape.

[0069] Specifically, in this embodiment, the knife is firstly aligned before cutting, such as Figure 8 As shown, it is preferred to first cut the upper and lower end surfaces of the cold stage body 1 along the XZ plane, and the cut surface is the reference surface for wire cutting processing, ensuring the consistency of the processed surface and the coordinates of the wire cutting equipment.

[0070] Then preferably according to Figure 8 The preset path shown is used to cut the Z-axis inverted cone structure. The pre-cut plane does not need to be cut again, that is, only the cutting Figure 8 The dotted part in the figure can quickly complete the empty routing path, saving processing time.

[0071] The wire cutting method of this embodiment can be used to prepare a rectangular inverted cone structure with high cutting accuracy, and the taper of the inverted cone can be precisely adjusted.

[0072] The present invention also provides a method for preparing a Dewar cooling stage, which is used to prepare the above-mentioned Dewar cooling stage. Fig. 9 As shown, a milling method is used, including:

[0073] Step C1, using a milling head to perform multi-layer milling on the surface of the cold stage body in a direction perpendicular to the cold stage body to form a columnar microstructure;

[0074] Step C2, tilting the milling head to mill the side of the columnar microstructure to obtain a Dewar cooling table with a plurality of bosses distributed on the surface.

[0075] Specifically, in this embodiment, Fig.10 As shown in (c), it is preferred to use a 0.1 diameter milling head for processing, which has low strength and a small feed amount each time. The microstructure can be formed into a columnar microstructure 5 through multi-layer milling, wherein each layer is preferably milled off 0.05 mm.

[0076] Then Fig.10 As shown in (d), the milling head is tilted by the robot arm to mill the side of the columnar microstructure, and finally an inverted cone structure is formed. During the milling process, cutting fluid can be sprayed on the processing point to improve the processing quality and efficiency.

[0077] The milling method of this embodiment has a high processing speed, and there is no oxide layer on the surface, so there is no need for corrosion (corrosion will increase the risk of material outgassing and there is a risk of reducing the vacuum life).

[0078] As a preferred embodiment, Fig.11 As shown, for bosses with at least one layer of steps, since the processing depth is usually greater than 1mm, and the spacing between bosses is usually greater than 4mm, and since ultrafast lasers are most efficient in processing microstructures with a depth of 0-1mm, as the depth increases, the thickness of the surface oxide layer increases, and the cone formed by the processed sidewalls becomes larger, making it difficult for the laser to be efficiently absorbed, the columnar microstructure can be processed by milling or wire cutting, and then the sidewalls of the columnar microstructure can be etched by laser, and can be layered and etched into a multi-level structure. Among them, if the columnar microstructure is in the shape of a cylinder, it can only be completed by milling.

[0079] The present invention also provides a refrigerated infrared detector, comprising the above-mentioned Dewar cooling stage.

[0080] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of this specification and illustrations should be included in the protection scope of the present invention.

Claims

1. A Dewar cooling stage, characterized in that: It comprises a cold platform body, wherein a plurality of bosses are distributed on the upper surface and / or the lower surface of the cold platform body, and the bosses are inverted cones.

2. The Dewar cooling stage according to claim 1, characterized in that: A plurality of grooves are formed on the surface of the cold stage body and are located between the bosses. The grooves are unidirectional grooves, annular grooves, spiral grooves, or staggered grooves.

3. The Dewar cooling stage according to claim 1, characterized in that: The projection of the boss on the surface of the cold stage body is in the shape of a regular hexagon, a triangle, a circle or a rectangle.

4. The Dewar cooling stage according to claim 3, characterized in that: The side length of the regular hexagon is 0.1 mm-0.5 mm, and the height of the boss is 0.1 mm-0.5 mm.

5. The Dewar cooling stage according to claim 1, characterized in that: At least one step is stacked between the boss and the cold stage body.

6. The Dewar cooling stage according to claim 5, characterized in that: The steps at each layer are in the shape of a regular cone, and / or a prism, and / or an inverted cone.

7. A method for preparing a Dewar cooling stage, characterized in that: For preparing the Dewar cooling stage as claimed in any one of claims 1 to 6, comprising: Step A1, using a laser to vertically etch the surface of the cold stage body to form a columnar microstructure; Step A2, aligning the focused spot of the laser to the bottom of the columnar microstructure, so as to perform tilted rotation cutting on the columnar microstructure to obtain a Dewar cooling stage with a plurality of bosses distributed on the surface.

8. A method for preparing a Dewar cooling stage, characterized in that: For preparing the Dewar cooling stage as claimed in any one of claims 1 to 6, comprising: Step B1, using wire cutting to flatten the surface of the cold stage body, and using the flattened surface as a reference surface for cutting processing; Step B2, performing wire cutting on the reference surface along a preset direction according to a preset path to obtain an inverted tapered strip groove, and then performing wire cutting on the reference surface along a direction perpendicular to the preset direction according to the preset path to obtain a Dewar cooling table with a plurality of bosses distributed on the surface; The preset path is a Z-shape and an inverted Z-shape connected in sequence, and the inverted Z-shape is obtained by mirroring the Z-shape.

9. A method for preparing a Dewar cooling stage, characterized in that: For preparing the Dewar cooling stage as claimed in any one of claims 1 to 6, comprising: Step C1, using a milling head to perform multi-layer milling on the surface of the cold stage body in a direction perpendicular to the cold stage body to form a columnar microstructure; Step C2, tilting the milling head to mill the side of the columnar microstructure to obtain a Dewar cooling table with a plurality of bosses distributed on the surface.

10. A refrigerated infrared detector, characterized in that: The method comprises a Dewar cooling stage as claimed in any one of claims 1 to 6.

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