Integrated mold of multi-stage micro thermoelectric cooling chip and preparation method of integrated mold

Abstract

The invention provides an integrated mold of a multistage micro thermoelectric cooling chip and a preparation method. The preparation method comprises the following steps: preparing crystal grains; coating soldering paste on the single surface of the ceramic substrate to mount the crystal grains; welding the crystal grains to form all levels of refrigeration chips; the back face of the single face of the ceramic substrate is coated with soldering paste; sequentially placing the refrigeration chips in the notches of the bottom-layer positioning plate and the middle positioning plate, placing the top pressing plate at the top, positioning the bottom-layer positioning plate, the middle positioning plate and the top pressing plate by adopting the positioning pins, and welding the refrigeration chips; and welding a lead. The method has the beneficial effects that the problems of difficulty in double-sided soldering paste coating, poor center positioning precision, non-uniform welding pressure, complex integration process, non-uniform welding heating of a middle interface, difficulty in lead welding and the like of the micro ceramic substrate are solved, and high-precision assembly and preparation of the multi-stage micro thermoelectric cooling chip are realized; the method is suitable for batch production of multistage micro thermoelectric cooling chips.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoelectric devices, and in particular relates to an integrated mold and a preparation method of a multi-stage micro thermoelectric cooling chip. Background Art

[0002] The multi-stage thermoelectric cooler is stacked in a cascade manner. The cold end of the lower thermoelectric module contacts the hot end of the higher thermoelectric module, absorbing the heat released by the module and ensuring the cold end temperature of the higher thermoelectric module. The multi-stage cooling method can provide a larger temperature difference, thereby achieving deep cooling temperature control of the heat dissipated power device. Several pairs of thermocouples are connected in series or in parallel to form a single-stage thermoelectric cooling chip. When direct current passes through, electrons migrate to achieve cooling. Several single-stage thermoelectric cooling modules are stacked and arranged and electrically connected to form a multi-stage thermoelectric cooler. The lower thermoelectric module absorbs the heat released by the higher thermoelectric module to obtain a lower temperature.

[0003] As the integration of equipment used in the fields of photoelectric detection, 5G / 6G communications, and precision astronomical observation continues to increase, the size and integration density of multi-stage thermoelectric coolers continue to increase, and multi-stage thermoelectric coolers are gradually developing in the direction of ultra-micro chips, multi-levels, and high temperature differences. The bottom layer size of a multi-stage ultra-micro thermoelectric cooling chip is usually less than 10mm×10mm, the top layer size is usually less than 3mm×3mm, and the total height does not exceed 5.0mm. Integrating hundreds of pairs of P and N pairs of components in a small space, and the spacing between components does not exceed 200μm, the center positioning of each level and the double-sided solder coating are difficult, and it is urgent to develop a high-precision, high-reliability integrated preparation method for multi-stage micro thermoelectric cooling chips. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an integrated mold and preparation method for a multi-stage micro-thermoelectric cooling chip, which effectively solves the technical problems of center positioning of each stage of the multi-stage micro-thermoelectric cooling chip and difficulty in double-sided solder coating, and overcomes the shortcomings of the prior art.

[0005] The technical solution adopted by the present invention is: an integrated mold for a multi-stage micro-thermoelectric cooling chip, including a bottom positioning plate, an intermediate positioning plate and a top pressing plate, wherein slots are provided at relative positions of the bottom positioning plate and the intermediate positioning plate for placing cooling chips at each stage, and a positioning pin is provided at the bottom of the intermediate positioning plate.

[0006] The present invention also provides a method for preparing a multi-stage micro thermoelectric cooling chip, which is prepared using the integrated mold as described above, and comprises the following steps:

[0007] preparing grains;

[0008] Coating solder paste on one side of the ceramic substrate to mount the crystal grain;

[0009] Welding the crystal grains to form cooling chips at various levels;

[0010] Applying solder paste on the back side of one side of the ceramic substrate;

[0011] The cooling chips of each level are sequentially placed into the notches of the bottom positioning plate and the middle positioning plate, the top pressing plate is placed on the top, the bottom positioning plate, the middle positioning plate and the top pressing plate are positioned using the positioning pins, and the cooling chips of each level are welded;

[0012] Solder the leads.

[0013] Further, in the step of preparing the grains, the steps include:

[0014] cutting the bismuth telluride crystal rod into wafers;

[0015] Coating an interface barrier layer and a welding transition layer on both sides of the wafer;

[0016] The wafer is cut into the dies.

[0017] Furthermore, the step of cutting the bismuth telluride crystal rod into wafers is performed by one or more of electric spark wire cutting, inner circle cutting, and multi-wire saw cutting, and the wafer thickness is 0.2 mm to 2.0 mm.

[0018] Furthermore, the roughening solution used for coating the interface barrier layer is one or more of hydrochloric acid, nitric acid or sulfuric acid, the type of activation solution used is hydrochloric acid, and the coating method is one of electroplating or chemical plating; the welding transition layer is Sn, Sn 63 Pb 37 Sn 95 Sb5 or Au 80 Sn 20 One or more of the above, the coating method is electroplating, chemical plating, hot dipping or thermal spraying.

[0019] Furthermore, in the step of coating solder paste on one side of a ceramic substrate to mount the grains, the ceramic substrate is made of one of aluminum oxide, aluminum nitride or beryllium oxide ceramics. When there is a difference in the number of metallized patterns on the front and back sides of the ceramic substrate, single-sided coating is performed on the side with fewer metallized patterns. The coating method is screen printing or precision dispensing technology. The amount of solder paste coated occupies 50% to 80% of the area of ​​the metallized pattern. During coating, the ceramic substrate is placed in an outer notch of a coating carrier with one side of the ceramic substrate facing outward.

[0020] Furthermore, in the step of welding the crystal grains to form various levels of cooling chips, the welding heating temperature is 240-400° C., the welding pressure is 100-1000 g, and the welding time is 1-10 min.

[0021] Furthermore, in the step of coating solder paste on the back side of one side of the ceramic substrate, the ceramic substrate is placed in the outer notch of the coating carrier, with the ceramic substrate facing inward on one side, so that the welded grains are embedded in the inner notch of the coating carrier.

[0022] Furthermore, the cooling chips at each level are welded by reflow welding, the welding temperature is 240-420° C., the welding pressure is 100-1000 g, and the welding time is 1-10 min.

[0023] Furthermore, in the step of welding the lead, laser welding is used, the welding temperature is 50-400°C, the welding time is 10-100s, and an inert gas is introduced during the welding process. The type of inert gas is argon or nitrogen, and the lead is one of copper, aluminum, silver or magnesium aluminum.

[0024] The advantages and positive effects of the present invention are as follows: by coating solder paste in steps and adopting an integrated mold, the problems of difficulty in double-sided solder paste coating of a micro-ceramic substrate, poor center positioning accuracy, uneven welding pressure, complex integration process, uneven heating of the intermediate interface welding, difficulty in lead welding, etc. in the integrated assembly process of a multi-stage micro-thermoelectric cooling chip are solved, and high-precision assembly and preparation of the multi-stage micro-thermoelectric cooling chip is achieved. The operation is simple and the chip is suitable for mass production of the multi-stage micro-thermoelectric cooling chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the assembly structure of a method for preparing a multi-stage micro thermoelectric cooling chip according to an embodiment of the present invention.

[0026] Figure 2 This is a chip explosion diagram of a method for preparing a multi-stage micro thermoelectric cooling chip according to an embodiment of the present invention.

[0027] Figure 3 The present invention is a flowchart of a method for preparing a multi-stage micro thermoelectric cooling chip according to an embodiment of the present invention.

[0028] Figure 4 It is a three-dimensional diagram of a coating carrier for a method of preparing a multi-stage micro thermoelectric cooling chip according to an embodiment of the present invention.

[0029] Figure 5 It is a cross-sectional view of a coating carrier in a method for preparing a multi-stage micro thermoelectric cooling chip according to an embodiment of the present invention.

[0030] Figure 6 It is a three-dimensional diagram of a pressurized tooling for a method of preparing a multi-stage micro thermoelectric cooling chip according to an embodiment of the present invention.

[0032] 1. Bottom positioning plate 2. Middle positioning plate 3. Top pressing plate

[0033] 4. Positioning pin 5. Crystal grain 6. Ceramic substrate

[0034] 7. Outer notch 8. Inner notch DETAILED DESCRIPTION

[0035] The embodiment of the present invention provides an integrated mold and a preparation method of a multi-stage micro thermoelectric cooling chip. The embodiment of the present invention is described below in conjunction with the accompanying drawings.

[0036] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "set" and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0037] like Figure 1 and Figure 2 As shown, an integrated mold of a multi-stage micro thermoelectric cooling chip in an embodiment of the present invention includes a bottom positioning plate 1, an intermediate positioning plate 2 and a top pressing plate 3. Notches are provided at the relative positions of the bottom positioning plate 1 and the intermediate positioning plate 2, the notches on the bottom positioning plate 1 are set as blind holes, and the notches on the intermediate positioning plate 2 are set as through holes. After the cooling chips at each level are prepared, they are sequentially placed in the notches of the bottom positioning plate 1 and the intermediate positioning plate 2 for serial integration and assembly. The notches are adapted to the cooling chips at each level. A positioning pin 4 is provided at the bottom of the intermediate positioning plate 2, which not only plays a supporting role, but also ensures that the centers of the notches of the bottom positioning plate 1 and the intermediate positioning plate 2 are aligned, thereby accurately positioning the cooling chips at each level. The number of positioning pins 4 is not limited. The thickness of the bottom positioning plate 1 and the top pressing plate 3 is greater than the thickness of the intermediate positioning plate 2. The material of the bottom positioning plate 1, the intermediate positioning plate 2, the top pressing plate 3 and the positioning pin 4 is not limited, and is preferably set to one of stainless steel, aluminum alloy, alumina ceramic or aluminum nitride ceramic.

[0038] A method for preparing a multi-stage micro thermoelectric cooling chip, such as Figure 3 As shown, the integrated mold preparation as described above includes the following steps:

[0039] S1, preparing grain 5;

[0040] The bismuth telluride crystal rod is cut into wafers, and an interface barrier layer and a welding transition layer are coated on both sides of the wafer by a coating method. The wafers after surface coating are cut into micro-sized grains 5 and placed in the loading area of ​​the component mounting system.

[0041] In this step, the compression strength of the N-type and P-type bismuth telluride crystal rods used is ≥140 MPa, the room temperature ZT value of the N-type bismuth telluride material is ≥0.9; and the room temperature ZT value of the P-type bismuth telluride material is ≥1.1.

[0042] In the process of cutting the bismuth telluride crystal rod, the cutting method is one or more of electric spark wire cutting, inner circle cutting or multi-wire saw cutting, and the thickness of the cut wafer is 0.2mm to 2.0mm.

[0043] In the process of coating the interface barrier layer and the welding transition layer on the wafer, the roughening liquid used for coating the interface barrier layer is one or more of concentrated hydrochloric acid, concentrated nitric acid or concentrated sulfuric acid, the activation liquid used is 25% dilute hydrochloric acid, and the coating method is electroplating or chemical plating. The main components of the welding transition layer are Sn, Sn 63 Pb 37 Sn 95 Sb5 or Au 80 Sn 20 One or more of the above, the coating method is electroplating, chemical plating, hot dipping or thermal spraying.

[0044] During the cutting process of the micro-sized crystal grains 5, the cutting method is one or more of an inner circle cutting machine, an electric spark wire cutting machine or a precision dicing machine, and the cross-sectional area of ​​the cut crystal grains 5 is 0.1×0.1mm~2.0×2.0mm. Before being placed in the loading area of ​​the component placement system, the micro-crystal grains 5 should be pasted on a blue film, a UV film, a pyrolytic film or placed in the loading area using a tape device array.

[0045] S2, coating solder paste on one side of the ceramic substrate 6 and mounting the die 5;

[0046] The solder paste is uniformly coated on the metallized pattern on one side of the ceramic substrate 6, and the mounting of tiny material components, namely, crystal grains 5, is achieved through a component mounting and die bonding process.

[0047] In this step, the solder paste is evenly coated on the single-sided metallization pattern of the ceramic substrate 6. The coating method is screen printing or precision dispensing technology. The amount of solder paste applied should occupy 50% to 80% of the metallization pattern area. The micro-component placement accuracy range is within ±30μm, and the angle accuracy is ≤±0.5°. When coating, place the ceramic substrate 6 in the outer notch 7 of the coating carrier. Figure 4As shown, the ceramic substrate 6 is placed with one side facing outward. The first layer is the first, and the second layer, the third layer, ... to the n+1th layer of the ceramic substrate 6 are placed upward in sequence. The solder paste coating step is repeated n+1 times to complete the single-sided solder paste coating of the first to n+1th layers of the ceramic substrate 6. The component mounting step is repeated n times to complete the component mounting of the first to nth layers of the ceramic substrate 6. Preferably, when there is a difference in the number of metallized patterns on the front and back sides of the ceramic substrate 6, the side with the smaller number of metallized patterns is coated and mounted. The material of the ceramic substrate 6 is one of aluminum oxide, aluminum nitride or beryllium oxide ceramics.

[0048] S3, welding crystal grains 5 to form cooling chips at various levels;

[0049] The single-sided π-type welding of each level of cooling chips is completed by heating and pressurizing. If there are n levels of cooling chips, the above single-sided π-type welding steps are repeated n times.

[0050] In this step, during the single-sided π-type welding process of each level of cooling chip welding, the welding heating temperature is 240-400°C, the welding pressure is 100-1000g, and the welding time is 1-10min. Repeat the single-sided π-type welding n times to complete the welding and curing of the ceramic substrate 6 after the material components from the first layer to the nth layer are mounted.

[0051] S4, coating solder paste on the back side of one side of the ceramic substrate 6;

[0052] The solidified single-sided π-shaped ceramic substrates of each level are placed in a coating carrier respectively, and the solder paste is evenly coated on the back side of the n-level single-sided π-shaped ceramic substrate 6, that is, the side of the ceramic substrate 6 where the crystal grains 5 are not welded.

[0053] In this step, the π side of the finished die 5 is placed into the coating carrier with the surface facing downward. Figure 5 As shown, the length and width dimensions L1 of the outer notch 7 of the coating carrier match the length and width dimensions L2 of the ceramic substrate 6, satisfying L1>L2 and 10μm≤L1-L2≤50μm. The depth H1 of the outer notch 7 of the coating carrier matches the thickness H2 of the ceramic substrate 6, satisfying H2>H1 and 10μm≤H2-H1≤100μm. The π surface of the grain 5 welded is embedded in the inner notch 8, requiring the height of the grain 5 to be less than the depth of the inner notch 8. After being placed horizontally, the solder paste coating on the back is completed. Repeat this step n-1 times to complete the double-sided solder paste coating of the n-1 ceramic substrates 6 from the 2nd layer to the nth layer.

[0054] S5, placing the cooling chips of each level into the notches of the bottom positioning plate and the middle positioning plate in sequence, placing the top pressing plate on the top, using positioning pins to position the bottom positioning plate, the middle positioning plate and the top pressing plate, and welding the cooling chips of each level;

[0055] In this step, the bottom positioning plate is placed on a horizontal table, the bottom ceramic substrate 6 after the solidification and welding material element is completed is placed into the notch of the bottom positioning plate, the middle positioning plate is stacked upward, and the middle ceramic substrate 6 after solidification and welding is placed into the notch of the middle positioning plate. After the n+1th layer of ceramic substrate 6 is placed, the top pressing plate is placed on the n+1th layer of ceramic substrate 6, and each plate is aligned in series through positioning pins. The entire multi-stage micro-thermoelectric cooling chip is pressurized by a pressurizing tool, and then welded. Preferably, reflow soldering is used. The temperature range of reflow soldering is 240-420°C, the welding pressure is 100-1000g, and the welding time is 1-10min. After welding is completed, the molds are removed one by one.

[0056] S6. Welding leads.

[0057] The lead welding of fine pitch pads is completed by laser welding method.

[0058] In this step, the dispensing pressure adjustment range is 0-1.0MPa, the negative pressure setting range is 0-20KPa, the laser welding temperature is 50-400℃, the temperature fluctuation range is ±5℃, the laser welding time is 10-100s, and a stable inert gas is introduced during the laser welding process, and the inert gas type is argon or nitrogen. The lead material is one of copper, aluminum, silver or magnesium aluminum.

[0059] Embodiment: A method for preparing a multi-stage micro thermoelectric cooling chip Figure 1 As shown, it is used to prepare a four-stage micro thermoelectric cooling chip. The structure of the four-stage micro thermoelectric cooling chip is as follows Figure 2 As shown: the first layer of ceramic substrate 6 has a length and width of 7.40mm×7.40mm and a thickness of 0.5mm, and the first level can mount 60 pairs of N / P type material components; the second layer of ceramic substrate 6 has a length and width of 7.40mm×7.40mm and a thickness of 0.5mm, and the second level can mount 31 pairs of N / P type material components; the third layer of ceramic substrate 6 has a length and width of 4.80mm×4.80mm and a thickness of 0.5mm, and the third level can mount 10 pairs of N / P type material components; the fourth layer of ceramic substrate 6 has a length and width of 3.0mm×3.0mm and a thickness of 0.5mm, and the fourth level can mount 4 pairs of N / P type material components; the fifth layer of ceramic substrate 6 has a length and width of 2.60mm×2.60mm. The preparation method comprises the following steps:

[0060] S1, preparing grain 5;

[0061] P-type and N-type bismuth telluride crystal rods with compressive strengths of 160MPa and 180MPa respectively were selected, the room temperature ZT value of the N-type bismuth telluride material was 0.98, and the room temperature ZT value of the P-type bismuth telluride material was 1.15. The bismuth telluride crystal rods were cut using the inner circle cutting method, and the thickness of the cut wafers was 0.50±0.02mm.

[0062] Place an N / P type wafer with a thickness of 0.50±0.02mm in a beaker container, add 5mol% sodium hydroxide and metal cleaning agent, and place it in an ultrasonic cleaning device for cleaning for 15 minutes. Then place the wafer in a solution of 37% concentrated hydrochloric acid and 75% concentrated nitric acid in a ratio of 2:1 for roughening, the roughening time is 10 minutes, and after cleaning with deionized water, the wafer is placed in 25% dilute hydrochloric acid for activation. The interface barrier layer and welding transition layer are coated on the surface of the material sheet by electroplating. The main component of the nickel plating solution is nickel sulfate, the nickel plating time is 10 minutes, and the current is 0.05A. The main component of the tin plating solution is tin methanesulfonate, the tin plating time is 20 minutes, and the current is 0.2A.

[0063] A precision dicing machine is used to cut the coated N / P type material wafer, the cutting rate is 3mm / s, the cross-sectional area of ​​the cut grain 5 is 0.4mm×0.4mm, the wafer is heated and pasted on the pyrolytic film, and the pyrolytic film is debonded after cutting, and the cut N / P type grain 5 array is placed in the component mounting loading area using a taping device.

[0064] S2, coating solder paste on one side of the ceramic substrate 6 and mounting the die 5;

[0065] The solder paste is applied to one side of the 1-5-layer ceramic substrate 6 by screen printing. The ceramic substrate 6 is made of aluminum nitride AlN. The 1-5-layer ceramic substrate 6 is a single-sided metallized pattern, and only the pattern surface is screen printed on one side. The 2-layer, 3-layer, and 4-layer ceramic substrate 6 is printed on the side with a smaller number of metallized patterns. The 1-5-layer aluminum nitride ceramic substrate 6 is placed in a coating carrier in sequence. The coating carrier is as follows: Figure 4 As shown, the length and width of the outer notch 7 of each layer of the coating carrier are 7.43mm×7.43mm, 4.83mm×4.83mm, 3.03mm×3.03mm, and 2.63mm×2.63mm, respectively, and the depth of the outer notch 7 of the coating carrier is 0.53mm. Install the steel mesh and apply Sn on the corresponding position of the mesh. 95 Sb5 solder paste, set the scraper to press down to complete the solder paste printing. The amount of solder paste applied accounts for 70% of the metallized pattern, and the printed solder paste thickness is 50μm. Use component placement and die bonding equipment to accurately mount the N / P type material component, that is, the grain 5, on the center position of the solder paste coated on the 1-4 layers of aluminum nitride ceramic substrate 6 to form 1-4 levels of uncured π-type.

[0066] S3, welding crystal grains 5 to form cooling chips at various levels;

[0067] The above-mentioned 1 to 4 levels of uncured π-type are placed on the lower resistance heating table, and a ceramic indenter is used to apply a 300g welding pressure. The welding temperature of the lower heating table is set to 320°C, and the welding time is 3min. The welding and curing of 1 to 4 levels of π-type are completed respectively, and the preparation of each level of cooling chips is completed.

[0068] S4, coating solder paste on the back side of one side of the ceramic substrate 6;

[0069] Place the cured 2-4 layers with one side facing downward in the coating carrier. Figure 5 As shown, the dimensions of the outer notch 7 of the coating carrier are 7.43mm×7.43mm, 4.83mm×4.83mm, and 3.03mm×3.03mm, respectively. The dimensions of the inner notch 8 are 5.0mm×5.0mm, 3.0mm×3.0mm, and 2.0mm×2.0mm, respectively, and the depth of the outer notch 7 of the coating carrier is 0.53mm. Repeat the printing process to complete the back screen printing of 2 to 4 levels of single-sided π.

[0070] S5, placing the cooling chips of each level into the notches of the bottom positioning plate 1 and the middle positioning plate 2 in sequence, placing the top pressing plate 3 on the top, using the positioning pins 4 to position the bottom positioning plate 1, the middle positioning plate 2 and the top pressing plate 3, and welding the cooling chips of each level;

[0071] Place the bottom positioning plate 1 on a horizontal table, place the bottom ceramic substrate 6 after the solidification and welding material components are completed into the slot of the bottom positioning plate 1, stack the middle positioning plate 2 upwards, and place the middle ceramic substrate 6 after solidification and welding into the slot of the middle positioning plate 2. The length and width of the slot are 30μm larger than the length and width of the corresponding ceramic substrate 6. The slot of the bottom positioning plate 1 is a blind hole with a depth of 0.5mm, and the slot of the middle positioning plate 2 is 1.0mm deep and is a through hole. Accumulate upwards in sequence until the fifth layer of ceramic substrate 6 is placed, then place the top pressing plate 3 on the fifth layer of ceramic substrate 6, and each plate is connected in series and aligned by three positioning pins 4. The material of the mold is stainless steel. Use the following method: Figure 6 The C-type pressurizing tool shown completes the pressurization of the overall mold and each ceramic substrate 6, and the pressure applied by the pressurizing tool is about 500g. The above mechanism is placed in a reflow soldering machine, the soldering temperature is 350°C, the soldering time is 5 minutes, and the overall soldering of the 4-level micro cooling chip is completed. After the soldering is completed, the molds are removed one by one.

[0072] S6. Welding leads.

[0073] A silver wire with a diameter of 0.27 mm and a length of 50 mm was placed at the center of the (-) and (+) Pad pads corresponding to a layer of ceramic substrate. A dispensing machine was used to apply solder paste on the (-) and (+) Pad pads corresponding to a layer of ceramic substrate. The solder paste thickness was about 70 μm, the dispensing pressure was 0.5 MPa, and the negative pressure was set to 10 KPa. Laser was used to locally heat the silver wire solder joints. Ar gas was stably introduced for protection during the laser welding process. The laser welding temperature was 260 ° C and the welding time was 30 s.

[0074] The advantages and positive effects of the present invention are:

[0075] By applying solder paste in steps and using an integrated mold, the problems of difficulty in double-sided solder paste coating on micro-ceramic substrates, poor center positioning accuracy, uneven welding pressure, complex integration process, uneven heating of the intermediate interface welding, and difficulty in lead welding in the integrated assembly process of multi-stage micro-thermoelectric cooling chips are solved. High-precision assembly and preparation of multi-stage micro-thermoelectric cooling chips is achieved, which is simple to operate and suitable for mass production of multi-stage micro-thermoelectric cooling chips.

[0076] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. An integrated mold for a multi-stage micro thermoelectric cooling chip, characterized in that: It comprises a bottom positioning plate, an intermediate positioning plate and a top pressing plate. Notches are arranged at the relative positions of the bottom positioning plate and the intermediate positioning plate for placing cooling chips at various levels. A positioning pin is arranged at the bottom of the intermediate positioning plate.

2. A method for preparing a multi-stage micro thermoelectric cooling chip, characterized in that: The integrated mold preparation as claimed in claim 1 comprises the following steps: preparing grains; Coating solder paste on one side of the ceramic substrate to mount the crystal grain; Welding the crystal grains to form cooling chips at various levels; Applying solder paste on the back side of one side of the ceramic substrate; The cooling chips of each level are sequentially placed into the notches of the bottom positioning plate and the middle positioning plate, the top pressing plate is placed on the top, the bottom positioning plate, the middle positioning plate and the top pressing plate are positioned using the positioning pins, and the cooling chips of each level are welded; Solder the leads.

3. The method for preparing a multi-stage micro thermoelectric cooling chip according to claim 2, characterized in that: In the step of preparing the grains, the steps include: cutting the bismuth telluride crystal rod into wafers; Coating an interface barrier layer and a welding transition layer on both sides of the wafer; The wafer is cut into the dies.

4. The method for preparing a multi-stage micro thermoelectric cooling chip according to claim 3, characterized in that: The step cuts the bismuth telluride crystal rod into wafers by one or more of electric spark wire cutting, inner circle cutting and multi-wire saw cutting, and the wafer thickness is 0.2 mm to 2.0 mm.

5. The method for preparing a multi-stage micro thermoelectric cooling chip according to claim 3, characterized in that: The roughening liquid used for coating the interface barrier layer is one or more of hydrochloric acid, nitric acid or sulfuric acid, the type of activation liquid used is hydrochloric acid, and the coating method is one of electroplating or chemical plating; the welding transition layer is Sn, Sn 63 Pb 37 Sn 95 Sb5 or Au 80 Sn 20 One or more of the above, the coating method is electroplating, chemical plating, hot dipping or thermal spraying.

6. A method for preparing a multi-stage micro thermoelectric cooling chip according to any one of claims 2 to 5, characterized in that: In the step of coating solder paste on one side of a ceramic substrate to mount the crystal grains, the ceramic substrate is made of one of aluminum oxide, aluminum nitride or beryllium oxide ceramics. When there is a difference in the number of metallized patterns on the front and back sides of the ceramic substrate, single-sided coating is performed on the side with fewer metallized patterns. The coating method is screen printing or precision dispensing technology. The amount of solder paste coated occupies 50% to 80% of the area of ​​the metallized pattern. During coating, the ceramic substrate is placed in an outer notch of a coating carrier with one side of the ceramic substrate facing outward.

7. The method for preparing a multi-stage micro thermoelectric cooling chip according to claim 6, characterized in that: The step welds the crystal grains to form various levels of cooling chips, the welding heating temperature is 240-400° C., the welding pressure is 100-1000 g, and the welding time is 1-10 min.

8. The method for preparing a multi-stage micro thermoelectric cooling chip according to claim 6, characterized in that: In the step of coating solder paste on the back side of one side of the ceramic substrate, the ceramic substrate is placed in the outer notch of the coating carrier, with the ceramic substrate facing inward on one side, so that the welded grains are embedded in the inner notch of the coating carrier.

9. A method for preparing a multi-stage micro thermoelectric cooling chip according to any one of claims 2-5 and 7-8, characterized in that: The cooling chips at each level are welded by reflow welding, the welding temperature is 240-420° C., the welding pressure is 100-1000 g, and the welding time is 1-10 minutes.

10. The method for preparing a multi-stage micro thermoelectric cooling chip according to claim 9, characterized in that: In the step of welding the lead, laser welding is used, the welding temperature is 50-400°C, the welding time is 10-100s, inert gas is introduced during the welding process, the type of inert gas is argon or nitrogen, and the lead is one of copper, aluminum, silver or magnesium aluminum.

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