High-reliability thermoelectric cooling fin and packaging method thereof

Abstract

This invention provides a high-reliability thermoelectric cooler, comprising a PN-type thermocouple pair with a nickel layer on its surface; an encapsulation connection layer laminated on the PN-type thermocouple pair; and a copper-clad substrate laminated on the encapsulation connection layer. The encapsulation connection layer is made of porous graphene-metal composite material. This invention connects the grains and the copper-clad ceramic substrate through the encapsulation connection layer, forming a conductive path. This invention utilizes a porous graphene-metal composite structure to replace traditional alloy solder. On one hand, the nano-needle-cone structure achieves low-temperature metallurgical bonding due to the nano-effect; on the other hand, porous graphene effectively enhances the strength of the connection layer. Simultaneously, as a flexible layer, it can absorb thermal stress. Furthermore, by changing the geometry of the porous graphene, the coefficient of thermal expansion of the interface layer can be controlled, thereby achieving effective thermal matching, reducing thermal stress under service conditions, improving device reliability, and extending service life.

Description

Technical Field

[0001] This invention relates to the field of semiconductor thermoelectric refrigeration technology, to a thermoelectric refrigeration chip and its preparation method, and particularly to a high-reliability thermoelectric refrigeration chip and its packaging method. Background Technology

[0002] Thermoelectric coolers utilize the Peltier effect of semiconductor materials. When direct current passes through a thermocouple made of two different semiconductor materials connected in series, heat is absorbed and released at the two ends of the thermocouple, achieving the purpose of cooling. Thermoelectric cooling systems have no sliding parts, making them suitable for applications with limited space, high reliability requirements, and no refrigerant contamination. They have broad application prospects in fields such as chip thermal management, high-frequency and high-speed optoelectronic devices, medical applications, and precise industrial temperature control. The structure of a thermoelectric cooler mainly includes a packaging substrate, P-type and N-type thermocouple pairs, and is formed by soldering. However, commonly used alloy solders gradually become brittle with increasing service time, leading to cracks under thermal stress and eventual failure. Simultaneously, frequent thermal shocks can cause defects due to thermal mismatch between the packaging substrate and the solder, and between the thermoelectric material and the metallization layer, thus affecting thermoelectric transport performance.

[0003] Therefore, finding a suitable way to solve the aforementioned problems of existing thermoelectric devices has become one of the focal points of widespread attention for many forward-thinking researchers in the field. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a thermoelectric cooler and its preparation method, particularly a high-reliability thermoelectric cooler and its packaging method. The present invention achieves solderless low-temperature metallurgical connection by constructing a nano-needle-cone structure layer at the packaging interface and using porous graphene as a flexible layer. This enhances the interface strength, and the resulting porous graphene-metal composite structure can effectively regulate interfacial thermal stress, reducing thermal stress damage to the interface during the service of the thermoelectric device.

[0005] This invention provides a thermoelectric cooling chip, comprising a PN-type thermocouple pair with a nickel layer laminated on its surface;

[0006] An encapsulation connection layer composited on the PN-type thermocouple pair;

[0007] A copper-clad substrate laminated on the encapsulation connection layer;

[0008] The encapsulation connection layer is made of porous graphene-metal composite material.

[0009] Preferably, the number of PN type thermocouple pairs includes one or more sets;

[0010] The PN type thermocouple pair includes P-type and N-type bismuth antimonide cuboid grain thermocouple pairs;

[0011] The thickness of the nickel layer is 1–3 μm.

[0012] Preferably, the copper clad layer on the surface of the copper-clad substrate is a patterned copper structure layer;

[0013] The copper-clad substrate includes a copper-clad ceramic substrate;

[0014] In the porous graphene-metal composite material, the metal includes copper and / or nickel.

[0015] Preferably, the porous graphene has a pore size of 100–300 nm;

[0016] The porous graphene includes monolayer graphene;

[0017] The porous graphene-metal composite material includes porous graphene and metal needles.

[0018] Preferably, a nano-metal needle-taper connection surface A is provided on the nickel layer on the surface of the thermocouple pair;

[0019] The copper layer on the surface of the copper-clad substrate is provided with a nano-metal needle-taper connection surface B.

[0020] The nano-metal needle-cone connecting surface A and the nano-metal needle-cone connecting surface B are heat-pressed and encapsulated with porous graphene to form the encapsulation connecting layer.

[0021] The nano-metal needles include nano-nickel needles and / or nano-copper needles.

[0022] Preferably, the diameter of the base of the nano-metal needle is 100–200 nm;

[0023] The length of the nano-metal needle-like cone is 300–500 nm;

[0024] The thermocouple pair and the copper-clad substrate are connected by an encapsulation connection layer, which connects the thermocouple pair die and the copper-clad substrate to form a conductive path.

[0025] Preferably, the thermoelectric cooling chip is obtained by hot-pressing and encapsulating a copper-clad substrate, a PN-type thermocouple pair, and porous graphene.

[0026] The pressure for the thermo-press packaging is 1–5 MPa;

[0027] The temperature for the hot-press encapsulation is 150–250°C;

[0028] The PN type thermocouple pair has an encapsulation connection layer and a copper-clad substrate on one or both sides.

[0029] This invention also provides a method for preparing a thermoelectric cooler, comprising the following steps:

[0030] 1) A nano-metal needle-cone structure is prepared on the surface of the copper structure layer of a copper-clad substrate to obtain a copper-clad substrate with nano-metal needle-cones on the surface.

[0031] A nickel metal barrier layer is deposited on the surface of a semiconductor material, and then a nano-metal needle-taper structure is fabricated on the nickel metal barrier layer to form the encapsulation connection surface A;

[0032] 2) Porous graphene is composited on the nano-metal needles on the copper-clad substrate with nano-metal needles on the surface obtained in the above steps to form the encapsulation connection surface B.

[0033] After the encapsulation connection surface A and the encapsulation connection surface B are joined together, they are thermo-pressed to form an encapsulation connection layer, thus obtaining a thermoelectric cooling chip.

[0034] Preferably, the surface comprises two sides;

[0035] After the encapsulation connection surface A, the process also includes the step of cutting cuboid grains;

[0036] In step 2), the specific steps for compositing porous graphene include:

[0037] a) Transferring graphene to porous SiN using a transfer medium x On the thin film, after removing the transfer medium, porous SiN X Porous graphene was prepared using a thin film as a template and plasma etching method.

[0038] b) Then, the porous graphene is transferred to the copper-clad substrate using a transfer medium, and after removing the transfer medium, a copper-clad substrate with porous graphene is obtained.

[0039] Preferably, the method for preparing the graphene includes CVD.

[0040] The porous SiN X Thin film preparation methods include photolithography and / or reactive particle etching;

[0041] The porous SiN X The pore size of the thin film is 100–400 nm;

[0042] The transfer medium includes PMMA.

[0043] This invention provides a thermoelectric cooler, comprising a PN-type thermocouple pair with a nickel layer laminated on its surface; an encapsulation connection layer laminated on the PN-type thermocouple pair; and a copper-clad substrate laminated on the encapsulation connection layer. The encapsulation connection layer is made of a porous graphene-metal composite material. Compared with existing technologies, this invention addresses the problem that in existing thermoelectric devices, the alloy solder gradually becomes brittle with increasing service time, leading to cracks under thermal stress and eventual failure. Frequent thermal shocks cause defects due to thermal mismatch between the encapsulation substrate and the solder, and between the thermoelectric material and the metallization layer, thus affecting thermoelectric transport performance. This invention argues that effectively absorbing and reducing thermal stress is a key issue in the structural design and packaging process of thermoelectric coolers.

[0044] This invention creatively designs a high-reliability thermoelectric cooler with a specific structure and composition, comprising a copper-clad ceramic substrate and a semiconductor thermocouple pair. A packaging connection layer connects the die and the copper-clad ceramic substrate to form a conductive path. The copper-clad ceramic substrate has a patterned copper structure layer, and the packaging connection layer is a composite structure of porous graphene, copper, and nickel. This invention utilizes the reinforcing effect of graphene and the nano-interface effect to achieve thermal matching at the packaging interface, reducing thermal stress under service conditions, improving device reliability, and extending service life.

[0045] The thermoelectric cooler provided by this invention includes a copper-clad ceramic substrate and multiple sets of nickel-plated P-type and N-type bismuth antimonide cuboid thermocouple pairs. The grains and the copper-clad ceramic substrate are connected by an encapsulation bonding layer to form a conductive path. This invention utilizes a porous graphene-metal composite structure to replace traditional alloy solder. On one hand, the nano-needle-cone structure achieves low-temperature metallurgical bonding due to the nano-effect; on the other hand, the porous graphene effectively enhances the strength of the bonding layer. Simultaneously, as a flexible layer, it can absorb thermal stress. Furthermore, by changing the geometry of the porous graphene, the thermal expansion coefficient of the interface layer can be controlled, thereby achieving effective thermal matching, reducing thermal stress under service conditions, improving device reliability, and extending service life. Attached Figure Description

[0046] Figure 1 This is a simplified schematic diagram illustrating the structure and packaging process of the thermoelectric cooling chip prepared according to an embodiment of the present invention. Detailed Implementation

[0047] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention and not for limiting the claims of the present invention.

[0048] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0049] There are no particular restrictions on the purity of any raw materials used in this invention. It is preferred to use analytical grade or conventional purity in the field of thermoelectric devices.

[0050] This invention provides a thermoelectric cooling chip, comprising a PN-type thermocouple pair with a nickel layer laminated on its surface;

[0051] An encapsulation connection layer composited on the PN-type thermocouple pair;

[0052] A copper-clad substrate laminated on the encapsulation connection layer;

[0053] The encapsulation connection layer is made of porous graphene-metal composite material.

[0054] In this invention, the number of PN-type thermocouple pairs preferably includes one or more sets.

[0055] In this invention, the PN-type thermocouple pair preferably includes P-type and N-type bismuth antimonide cuboid grain thermocouple pairs.

[0056] In this invention, the thickness of the nickel layer is preferably 1 to 3 μm, more preferably 1.4 to 2.6 μm, and even more preferably 1.8 to 2.2 μm.

[0057] In this invention, the copper cladding layer on the surface of the copper-clad substrate is preferably a patterned copper structure layer.

[0058] In this invention, the copper-clad substrate preferably includes a copper-clad ceramic substrate.

[0059] In this invention, the metal in the porous graphene-metal composite material preferably includes copper and / or nickel, more preferably copper or nickel.

[0060] In this invention, the pore size of the porous graphene is preferably 100-300 nm, more preferably 140-260 nm, and even more preferably 180-220 nm.

[0061] In this invention, the porous graphene preferably comprises monolayer graphene.

[0062] In this invention, the porous graphene-metal composite material preferably includes porous graphene and metal needles.

[0063] In this invention, a nano-metal needle-like connecting surface A is preferably provided on the nickel layer of the thermocouple pair surface. Specifically, it should be noted that in this invention, before hot-pressing encapsulation, a nano-metal needle-like surface A is preferably provided on the nickel layer of the thermocouple pair surface. In the encapsulation connecting layer formed after hot-pressing encapsulation, the nano-metal needle-like surface can partially retain its original morphology, completely retain its original morphology, or not retain its original morphology at all.

[0064] In this invention, a nano-metal needle-like connecting surface B is preferably provided on the copper layer of the copper-clad substrate surface. Specifically, it should be noted that in this invention, before thermoforming, a nano-metal needle-like surface B is preferably provided on the copper layer of the copper-clad substrate surface. In the encapsulation connecting layer formed after thermoforming, the nano-metal needle-like surface can partially retain its original morphology, retain its original morphology completely, or retain none of its original morphology.

[0065] In this invention, the nano-metal needle-cone connecting surface A, the nano-metal needle-cone connecting surface B, and the porous graphene are preferably encapsulated by hot pressing to form the encapsulation connecting layer.

[0066] In this invention, the nano-metal needle cone preferably includes a nano-nickel needle cone and / or a nano-copper needle cone, more preferably a nano-nickel needle cone or a nano-copper needle cone.

[0067] In this invention, the diameter of the cone base of the nano-metal needle is preferably 100-200 nm, more preferably 120-180 nm, and even more preferably 140-160 nm.

[0068] In this invention, the length of the nano-metal needle is preferably 300-500 nm, more preferably 340-460 nm, and even more preferably 380-420 nm.

[0069] In this invention, the thermocouple pair and the copper-clad substrate are connected by an encapsulation connection layer, which connects the thermocouple pair die and the copper-clad substrate, preferably forming a conductive path.

[0070] In this invention, the thermoelectric cooling chip is preferably obtained by hot-pressing and encapsulating a copper-clad substrate, a PN-type thermocouple pair, and porous graphene.

[0071] In this invention, the pressure of the hot-pressing encapsulation is preferably 1 to 5 MPa, more preferably 1.5 to 4.5 MPa, more preferably 2 to 4 MPa, and even more preferably 2.5 to 3.5 MPa.

[0072] In this invention, the temperature of the hot-press encapsulation is preferably 150-250°C, more preferably 170-230°C, and even more preferably 190-210°C.

[0073] In this invention, one or both sides of the PN-type thermocouple pair are preferably composited with an encapsulation connection layer and a copper-clad substrate.

[0074] This invention aims to complete and refine the overall manufacturing process, better ensure the specific thermoelectric cooler structure, improve the reliability of thermoelectric devices, and extend their service life. The aforementioned thermoelectric cooler can specifically have the following structure:

[0075] A thermoelectric cooling chip includes a copper-clad ceramic substrate and multiple sets of nickel-plated P-type and N-type bismuth antimonide cuboid thermocouple pairs. The grains and the copper-clad ceramic substrate are connected by an encapsulation connection layer to form a conductive path. The copper-clad ceramic substrate has a patterned copper structure layer, and the encapsulation connection layer is a composite structure of porous graphene, copper, and nickel.

[0076] Specifically, the porous graphene has a pore size of 100–300 nm.

[0077] Specifically, the composite structure of porous graphene with copper and nickel can be a composite structure of porous graphene-copper, a composite structure of porous graphene-nickel, or a composite structure of porous graphene-copper-nickel.

[0078] This invention provides a method for preparing a thermoelectric cooling chip, comprising the following steps:

[0079] 1) A nano-metal needle-cone structure is prepared on the surface of the copper structure layer of a copper-clad substrate to obtain a copper-clad substrate with nano-metal needle-cones on the surface.

[0080] A nickel metal barrier layer is deposited on the surface of a semiconductor material, and then a nano-metal needle-taper structure is fabricated on the nickel metal barrier layer to form the encapsulation connection surface A;

[0081] 2) Porous graphene is composited on the nano-metal needles on the copper-clad substrate with nano-metal needles on the surface obtained in the above steps to form the encapsulation connection surface B.

[0082] After the encapsulation connection surface A and the encapsulation connection surface B are joined together, they are thermo-pressed to form an encapsulation connection layer, thus obtaining a thermoelectric cooling chip.

[0083] The present invention first prepares a nano-metal needle-cone structure on the surface of the copper structure layer of a copper-clad substrate, thereby obtaining a copper-clad substrate with nano-metal needle-cones on the surface.

[0084] A nickel metal barrier layer is deposited on the surface of a semiconductor material, and then a nano-metal needle-taper structure is fabricated on the nickel metal barrier layer to form the encapsulation connection surface A.

[0085] In this invention, the surface preferably comprises two sides.

[0086] In this invention, after the encapsulation connection surface A is described, the step of cutting cuboid grains is preferably included.

[0087] In this invention, porous graphene is further composited onto the nano-metal needles on the copper-clad substrate with nano-metal needles on the surface obtained in the above steps to form the encapsulation connection surface B.

[0088] After the encapsulation connection surface A and the encapsulation connection surface B are joined together, they are thermo-pressed to form an encapsulation connection layer, thus obtaining a thermoelectric cooling chip.

[0089] In this invention, step 2), the specific steps of compositing porous graphene, preferably include:

[0090] a) Graphene was transferred onto a porous SiNx film using a transfer medium. After removing the transfer medium, porous graphene was prepared using a porous SiNx film as a template by plasma etching.

[0091] b) Then, the porous graphene is transferred to the copper-clad substrate using a transfer medium, and after removing the transfer medium, a copper-clad substrate with porous graphene is obtained.

[0092] This invention first uses a transfer medium to transfer graphene onto a porous SiNx film. After removing the transfer medium, porous graphene is prepared using the porous SiNx film as a template by plasma etching.

[0093] In this invention, the graphene is preferably prepared by CVD.

[0094] In this invention, the method for preparing the porous SiNX thin film preferably includes photolithography and / or reactive particle etching, and more preferably photolithography or reactive particle etching.

[0095] In this invention, the pore size of the porous SiNX thin film is preferably 100-400 nm, more preferably 150-350 nm, and even more preferably 200-300 nm.

[0096] In this invention, the transfer medium preferably comprises PMMA.

[0097] Finally, the invention uses a transfer medium to transfer porous graphene onto a copper-clad substrate, and then removes the transfer medium to obtain a copper-clad substrate with porous graphene.

[0098] This invention aims to complete and refine the overall manufacturing process, better ensure the specific thermoelectric cooler structure, improve the reliability of thermoelectric devices, and extend their service life. The packaging method for the aforementioned thermoelectric cooler can specifically include the following steps:

[0099] Bismuth antimonide material was sliced ​​and a nickel metal barrier layer was deposited on both sides. Then, a nano-metal needle-cone structure was prepared on the nickel barrier layer to form the encapsulation connection surface A. After that, cuboid grains of a certain size were cut out according to the design requirements.

[0100] Nanoneedle-cone structures were fabricated on the copper structure layer of a copper-clad ceramic substrate;

[0101] Porous graphene material was prepared and then transferred to the surface of a nano-needle-cone structure on a copper-clad ceramic substrate to form an encapsulation connection surface B.

[0102] After aligning the two package connector surfaces, apply a certain amount of pressure and temperature to achieve the package connection.

[0103] Specifically, the applied pressure is 1–5 MPa and the temperature is 150–250 °C.

[0104] Specifically, the metal type of the nano-metal needle-cone structure is copper or nickel, with a cone base diameter of 100-200 nanometers and a length of 300-500 nanometers.

[0105] The present invention provides a high-reliability thermoelectric cooler and its packaging method. By constructing a nano-needle-cone structure layer at the packaging interface and using porous graphene as a flexible layer, the present invention achieves solderless low-temperature metallurgical connection, enhancing interface strength. Simultaneously, the formed porous graphene-metal composite structure effectively regulates interface thermal stress, reducing thermal stress damage to the interface during thermoelectric device service. The high-reliability thermoelectric cooler with a specific structure and composition designed in this invention includes a copper-clad ceramic substrate and a semiconductor thermocouple pair. The grains and the copper-clad ceramic substrate are connected by a packaging connection layer to form a conductive path. The packaging connection layer is a composite structure of porous graphene, copper, and nickel. This invention utilizes the reinforcing effect of graphene and the nano-interface effect to achieve thermal matching at the packaging interface, reducing thermal stress under service conditions, improving device reliability, and extending service life.

[0106] The thermoelectric cooler provided by this invention includes a copper-clad ceramic substrate and multiple sets of nickel-plated P-type and N-type bismuth antimonide cuboid thermocouple pairs. The grains and the copper-clad ceramic substrate are connected by an encapsulation layer to form a conductive path. The encapsulation layer is a composite structure of porous graphene, copper, and nickel. This invention utilizes a porous graphene-metal composite structure to replace traditional alloy solder. On one hand, the nano-needle-cone structure achieves low-temperature metallurgical bonding due to the nano-effect; on the other hand, the porous graphene effectively enhances the strength of the bonding layer. Simultaneously, as a flexible layer, it can absorb thermal stress. Furthermore, by changing the geometry of the porous graphene, the thermal expansion coefficient of the interface layer can be controlled, thereby achieving effective thermal matching, reducing thermal stress under service conditions, improving device reliability, and extending service life.

[0107] To further illustrate the present invention, the following describes in detail a thermoelectric cooling chip and its preparation method provided by the present invention with reference to embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. They are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0108] Example 1

[0109] See Figure 1 , Figure 1This is a simplified schematic diagram illustrating the structure and packaging process of the thermoelectric cooling chip prepared according to an embodiment of the present invention.

[0110] In this diagram, 1 represents a nano-nickel needle-cone structure, 2 represents a metallic nickel layer, 3 represents a nickel needle-cone structure, 4 represents a nickel needle-cone structure, 5 represents a nickel needle-cone structure, 6 represents a copper surface layer of a copper-clad ceramic substrate, 7 represents a copper-clad ceramic substrate, 8 represents the applied pressure, and 9 represents a hot plate.

[0111] like Figure 1 As shown, the packaging method of the thermoelectric cooling chip of the present invention includes:

[0112] (1) The bonding surface of the thermoelectric element 3 was cleaned using the standard RCA process. Then, 1 μm thick nickel 2 (Ni) was deposited on the substrate by sputtering. Finally, nano-nickel needle-cone structures 1 were prepared on the nickel layer. The method included: the raw materials used were nickel chloride hexahydrate (200 g / L), boric acid (35 g / L), ammonia (10%), hydrochloric acid (10%), and crystallization adjuster (200 g / L). In the electrodeposition, the anode was an electrolytic nickel plate (99.9%), the cathode was a copper sheet (99.5%), the temperature was 60 degrees Celsius, the growth time was 12 min, the current density was 1 ASD, and the pH value was 4.0. The nano-nickel needle-cone structures 1 were obtained with an average cone diameter of 100 nm and an average length of 300 nm. After completion, they were granulated and cleaned.

[0113] (2) Using the method described in step (1), a nano-nickel needle-taper structure 5 is prepared on the copper surface 6 of the copper-clad ceramic substrate 7 as a connecting surface.

[0114] (3) Prepare porous graphene 4 and transfer it to the bonding surface described in step (2). Specific steps include: 1) preparing a single layer of graphene on copper foil using a CVD method; 2) preparing porous SiN using photolithography and reactive particle etching. x Thin film with a pore size of 300 nm; 3) Transferring monolayer graphene to porous SiN using PMMA x 4) After removing PMMA, porous graphene is prepared by plasma etching using porous SiNx film as template, with an average pore size of 100 nanometers; 5) The porous graphene is transferred to the connecting surface described in step (2) using PMMA, and then PMMA is dissolved and removed.

[0115] (4) After aligning the porous graphene encapsulation connection surface formed in step (3) with the encapsulation connection surface formed in step (1), apply a pressure of 1 MPa and apply a temperature of 250°C using a hot plate 9. The encapsulation connection is completed after 30 minutes.

[0116] (5) Use the same method to complete the encapsulation connection between the other side of the die and the ceramic substrate.

[0117] The above provides a detailed description of a high-reliability thermoelectric cooler and its packaging method provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the textual description of the claims, or if they include equivalent structural elements that are not substantially different from the textual description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A thermoelectric cooling element, characterized in that, Including PN-type thermocouple pairs with a nickel layer on their surface; An encapsulation connection layer composited on the PN-type thermocouple pair; A copper-clad substrate laminated on the encapsulation connection layer; The encapsulation connection layer is made of porous graphene-metal composite material; The porous graphene-metal composite material includes porous graphene and metal needles; The nickel layer on the surface of the thermocouple pair is provided with a nano-metal needle-taper connection surface A; The copper layer on the surface of the copper-clad substrate is provided with a nano-metal needle-taper connection surface B. The nano-metal needle-cone connecting surface A and the nano-metal needle-cone connecting surface B are heat-pressed and encapsulated with porous graphene to form the encapsulation connecting layer.

2. The thermoelectric cooling element according to claim 1, characterized in that, The number of PN-type thermocouple pairs includes one or more sets; The PN type thermocouple pair includes P-type and N-type bismuth antimonide cuboid grain thermocouple pairs; The thickness of the nickel layer is 1~3μm.

3. The thermoelectric cooling element according to claim 1, characterized in that, The copper clad layer on the surface of the copper-clad substrate is a patterned copper structure layer; The copper-clad substrate includes a copper-clad ceramic substrate; In the porous graphene-metal composite material, the metal includes copper and / or nickel.

4. The thermoelectric cooling element according to claim 1, characterized in that, The porous graphene has a pore size of 100~300nm; The porous graphene includes monolayer graphene.

5. The thermoelectric cooling element according to claim 1, characterized in that, The nano-metal needles include nano-nickel needles and / or nano-copper needles.

6. The thermoelectric cooling element according to claim 5, characterized in that, The diameter of the base of the nano-metal needle is 100~200nm; The length of the nano-metal needle-like cone is 300~500 nm; The thermocouple pair and the copper-clad substrate are connected by an encapsulation connection layer, which connects the thermocouple pair die and the copper-clad substrate to form a conductive path.

7. The thermoelectric cooling element according to claim 5, characterized in that, The thermoelectric cooling chip is obtained by hot-pressing and encapsulating a copper-clad substrate, a PN-type thermocouple pair, and porous graphene. The pressure for the thermo-press sealing is 1~5MPa; The temperature for the hot-press encapsulation is 150~250℃; The PN type thermocouple pair has an encapsulation connection layer and a copper-clad substrate on one or both sides.

8. A method for preparing a thermoelectric cooling element, characterized in that, Includes the following steps: 1) A nano-metal needle-cone structure is prepared on the surface of the copper structure layer of a copper-clad substrate to obtain a copper-clad substrate with nano-metal needle-cones on the surface. A nickel metal barrier layer is deposited on the surface of a semiconductor material, and then a nano-metal needle-taper structure is fabricated on the nickel metal barrier layer to form the encapsulation connection surface A; 2) Porous graphene is composited on the nano-metal needles on the copper-clad substrate with nano-metal needles on the surface obtained in the above steps to form the encapsulation connection surface B. After the encapsulation connection surface A and the encapsulation connection surface B are joined together, they are thermo-pressed to form an encapsulation connection layer, thus obtaining a thermoelectric cooling chip.

9. The preparation method according to claim 8, characterized in that, The surface includes two sides; After the encapsulation connection surface A, the process also includes the step of cutting cuboid grains; In step 2), the specific steps for compositing porous graphene include: a) Transferring graphene to porous SiN using a transfer medium x On the thin film, after removing the transfer medium, porous SiN X Porous graphene was prepared using a thin film as a template and plasma etching method. b) Then, the porous graphene is transferred to the copper-clad substrate using a transfer medium, and after removing the transfer medium, a copper-clad substrate with porous graphene is obtained.

10. The preparation method according to claim 9, characterized in that, The preparation methods of the graphene include CVD method; The porous SiN X Thin film preparation methods include photolithography and / or reactive particle etching; The porous SiN X The pore size of the thin film is 100~400nm; The transfer medium includes PMMA.

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