Dual-stage thermoelectric refrigeration device with stepless ceramic substrate and method of manufacturing the same

Abstract

The application provides a two-stage thermoelectric refrigeration device without ceramic substrates between stages and a preparation method thereof. The two-stage thermoelectric refrigeration device comprises a lower substrate, an upper substrate, a conductive copper sheet, a first-stage thermoelectric particle array and a second-stage thermoelectric particle array, the first-stage thermoelectric particle array is arranged alternately by P-type thermoelectric particles and N-type thermoelectric particles, the second-stage thermoelectric particle array is arranged alternately by P-type thermoelectric particles and N type thermoelectric particles, the lower substrate is connected with the conductive copper sheet and the first-stage thermoelectric particle array in sequence, the upper substrate is connected with the conductive copper sheet and the second-stage thermoelectric particle array in sequence, and the first-stage thermoelectric particle array and the second-stage thermoelectric particle array are alternately stacked by P-type thermoelectric particles and N-type thermoelectric particles and are welded through the metalized surfaces of the thermoelectric particles. The application optimizes the stacking structure of the upper and lower P / N particles, avoids the use of the ceramic substrates between stages, significantly reduces the thermal resistance, reduces the production cost, and improves the refrigeration efficiency and reliability of the device.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor thermoelectric refrigeration technology, and particularly relates to a two-stage thermoelectric refrigeration device with a stepless ceramic substrate and its preparation method. Background Technology

[0002] Traditional single-stage thermoelectric coolers (TECs) achieve cooling based on the Peltier effect, but their maximum cooling temperature difference typically does not exceed 72K. In fields such as infrared detectors and cryogenic medical devices, multi-stage TEC structures are generally required to meet deep cryogenic conditions (maximum cooling temperature difference greater than 90K). Multi-stage TECs connect multiple single-stage TEC units electrically in series and thermally stacked, making the hot end of the previous stage the cold end of the next, thus achieving a larger temperature difference that single-stage devices cannot achieve. The fabrication of multi-stage TEC devices faces significant challenges, including low inter-stage interface resistance, low thermal resistance, and high reliability requirements; matching and integration processes of thermoelectric materials at each stage; and miniaturization, high yield, and cost-controllable manufacturing of the overall device. Therefore, developing innovative multi-stage TEC device structural designs, interface processing technologies, and efficient and stable fabrication methods is crucial for improving device performance and reliability and promoting their application in cutting-edge fields. Two-stage TEC devices are the most widely used multi-stage TEC products, achieving temperature differences of around 90K.

[0003] Currently, the lower and upper stages of a dual-stage TEC are mainly connected via high thermal conductivity ceramic substrates such as AlN and Al2O3, combined with copper filling through internal openings in the ceramic substrate or external soldering. This patent proposes to achieve the circuit connection between the upper and lower stages of a dual-stage TEC by changing the way the P / N particles are stacked themselves. This avoids the use of high thermal conductivity ceramic plates between the upper and lower stages of the dual-stage TEC, reducing costs while effectively reducing interlayer thermal resistance, improving the overall thermal conductivity of the device, and optimizing the cooling efficiency under actual operating conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the problems of high interstage thermal resistance, high manufacturing cost and complex process caused by the reliance on intermediate ceramic plate connection in the existing technology of two-stage thermoelectric cooling devices. The invention provides a two-stage thermoelectric cooling device without interstage ceramic substrate and its preparation method. By optimizing the stacking structure of P / N particles in the upper and lower layers, the use of interstage ceramic plates is avoided, the thermal resistance is significantly reduced, the production cost is reduced, and the cooling efficiency and reliability of the device are improved at the same time.

[0005] To address the aforementioned technical problems, this invention provides a two-stage thermoelectric cooling device with a stepless ceramic substrate. The two-stage thermoelectric cooling device includes a lower substrate, an upper substrate, a conductive copper sheet, a first-stage thermoelectric particle array, and a second-stage thermoelectric particle array. The first-stage thermoelectric particle array is composed of alternating P-type and N-type thermoelectric particles; the second-stage thermoelectric particles are also composed of alternating P-type and N-type thermoelectric particles. The lower substrate is sequentially connected to a conductive copper sheet and a first-stage thermoelectric particle array; the upper substrate is sequentially connected to a conductive copper sheet and a second-stage thermoelectric particle array. The first-stage thermoelectric particle array and the second-stage thermoelectric particle array are arranged vertically opposite each other. Between the two arrays, P-type thermoelectric particles and N-type thermoelectric particles are stacked in a crisscross pattern. The P-type thermoelectric particles of the first-stage array and the N-type thermoelectric particles of the second-stage array are alternately bonded, and the P-type thermoelectric particles of the second-stage array and the N-type thermoelectric particles of the first-stage array are alternately bonded. The electrical connection between the two arrays is achieved by welding the metallized contact surfaces of the thermoelectric particles.

[0006] Furthermore, in the aforementioned two-stage thermoelectric cooling device, the upper substrate and the lower substrate are made of highly thermally conductive insulating materials, such as alumina, aluminum nitride, or beryllium oxide.

[0007] Furthermore, in the aforementioned two-stage thermoelectric cooling device, the P-type thermoelectric particles and N-type thermoelectric particles are made of bismuth telluride-based thermoelectric materials.

[0008] Furthermore, in the aforementioned two-stage thermoelectric cooling device, both the upper and lower surfaces of the P-type and N-type thermoelectric particles are coated with nickel and copper metal films.

[0009] In the aforementioned two-stage thermoelectric cooling device, the nickel layer has a thickness of 1 μm to 20 μm, and the copper layer has a thickness of 1 μm to 100 μm.

[0010] Furthermore, in the aforementioned two-stage thermoelectric cooling device, the dimensions of the P-type thermoelectric particles and the N-type thermoelectric particles satisfy the condition that the length is greater than twice the width.

[0011] In the aforementioned two-stage thermoelectric cooling device, the conductive copper sheet on one side of the upper substrate is fixed using DBC (Direct Bonded Copper), AMB (Active Metal Brazing), DPC (Direct Plating Copper), or adhesive bonding processes, and the second-stage thermoelectric particle array is welded to the conductive copper sheet; the conductive copper sheet on one side of the lower substrate is fixed using DBC, AMB, DPC, or adhesive bonding processes, and the first-stage thermoelectric particle array is welded to the conductive copper sheet.

[0012] Based on a general technical concept, the present invention also provides a method for fabricating the aforementioned two-stage thermoelectric refrigeration device, the method comprising the following steps: S1. Cut the upper and lower substrates to the same size and fix the conductive copper sheet; prepare P-type bismuth telluride-based thermoelectric materials using zone melting, hot pressing, hot extrusion, or plasma discharge sintering; cut the P-type bismuth telluride-based thermoelectric materials into wafers using an inner circle dicing machine or a multi-wire dicing machine; deposit nickel and copper metal films on both sides of the wafers using electroplating, chemical plating, or magnetron sputtering processes; finally, cut the P-type thermoelectric particles using a dicing machine or a multi-wire dicing machine; prepare N-type thermoelectric particles using the same method. S2. Apply solder paste to the surface of the copper strip on the lower substrate. Use a die bonder to attach P-type and N-type thermoelectric particles to the corresponding positions on the copper strip. Through reflow soldering, the particles are firmly soldered to the lower substrate to form the first-stage thermoelectric particle array. Apply solder paste to the surface of the copper strip on the upper substrate. Use a die bonder to attach P-type and N-type thermoelectric particles to the corresponding positions on the copper strip. Through reflow soldering, the particles are firmly soldered to the upper substrate to form the second-stage thermoelectric particle array. S3. Apply solder paste to the surface of the first-stage thermoelectric particle array or the second-stage thermoelectric particle array, press and fix the upper and lower substrates together, and alternately stack the first-stage thermoelectric particle array and the second-stage thermoelectric particle array. Reflow soldering completes the device fabrication. Compared with the prior art, the advantages of the present invention are: (1) This invention provides a two-stage thermoelectric cooling device with a ceramic substrate without interstages. By eliminating the intermediate ceramic plate and interstage solder layer, the overall thermal resistance of the two-stage device can be significantly reduced, and the interface thermal resistance can be reduced by about 30%, thereby improving the overall heat conduction efficiency. This can directly reduce the cost of the device.

[0013] (2) This invention provides a two-stage thermoelectric cooling device with a stepless ceramic substrate. It proposes that the orthogonal stacking structure of P particles and N particles can disperse thermal stress, reduce thermal cycling fatigue failure, and improve the overall reliability and lifespan of the device.

[0014] (3) The present invention provides a method for preparing a two-stage thermoelectric refrigeration device with a stepless ceramic substrate. The preparation process is simple and can be applied to industrial production. Attached Figure Description

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0016] Figure 1 The particle arrangement in the dual-stage TEC2-179-179-XX device. Detailed Implementation

[0017] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0018] The materials, reagents, and instruments used in the following examples are all commercially available. Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art.

[0019] Example 1 A two-stage thermoelectric cooling device TEC2-179-179-XX based on a stepless ceramic substrate includes a lower substrate, an upper substrate, a conductive copper sheet, a first-stage thermoelectric particle array, and a second-stage thermoelectric particle array. The first-stage thermoelectric particle array is composed of P-type thermoelectric particles and N-type thermoelectric particles arranged alternately; the second-stage thermoelectric particles are also composed of P-type thermoelectric particles and N-type thermoelectric particles arranged alternately. The lower substrate is connected in sequence to a conductive copper sheet and a first-stage thermoelectric particle array; the upper substrate is connected in sequence to a conductive copper sheet and a second-stage thermoelectric particle array. The first-stage thermoelectric particle array and the second-stage thermoelectric particle array are arranged opposite each other. Between the two arrays, P-type thermoelectric particles and N-type thermoelectric particles are stacked in a crisscross pattern. The P-type thermoelectric particles of the first-stage array are alternately attached to the N-type thermoelectric particles of the second-stage array, and the P-type thermoelectric particles of the second-stage array are alternately attached to the N-type thermoelectric particles of the first-stage array. The electrical connection between the two arrays is achieved by welding the metallized contact surfaces of the thermoelectric particles.

[0020] Furthermore, both the P-type and N-type thermoelectric particles are made of bismuth telluride-based thermoelectric materials, and both types are coated with nickel and copper metal films. The nickel layer thickness is 1 μm to 20 μm; the copper layer thickness is 1 μm to 100 μm. Additionally, the thermoelectric particles are sized such that the length is greater than twice the width.

[0021] Furthermore, the upper substrate and the lower substrate are made of highly thermally conductive insulating materials such as aluminum oxide, aluminum nitride, or beryllium oxide.

[0022] Its preparation methods include: (1) Ceramic substrate processing: Two alumina ceramic plates are selected as the upper and lower substrates, and the dimensions of the upper and lower substrates are both 27mm×27mm×0.38mm. On the upper substrate, copper conductive strips with dimensions of 3.6mm×1.4mm×0.1mm and 1.7mm×1.7mm×0.1mm are prepared using the DBC process; on the lower substrate, copper conductive strips with dimensions of 3.6mm×0.75mm×0.1mm and 1.7mm×1.7mm×0.1mm are prepared using the DBC process (conductive copper sheets can also be fixed using DBC, AMB, DPC or adhesive processes).

[0023] (2) P-type bismuth telluride-based thermoelectric materials were prepared by hot pressing. The P-type bismuth telluride-based thermoelectric materials were cut into wafers with a thickness of 0.85 mm and a thickness of 0.50 mm using an inner circle dicing machine. A nickel layer with a thickness of 10 μm and a copper layer with a thickness of 50 μm were deposited on both sides of the wafer by magnetron sputtering. Finally, P-type thermoelectric particles with a length of 1.6 mm and a width of 0.65 mm were cut using a dicing machine or a multi-wire dicing machine.

[0024] N-type thermoelectric particles of the same size were prepared using the same method.

[0025] (3) Lower substrate assembly and soldering: Apply 10 μm thick solder paste to the surface of the copper strip of the lower substrate, and use a die bonder to bond the P-type thermoelectric particles and N-type thermoelectric particles according to... Figure 1 The method involves precisely attaching the particles to the corresponding positions of the current-guiding copper strip, and then using a reflow soldering process to achieve a stable bond between the particles and the substrate.

[0026] (4) Upper substrate assembly and soldering: Apply 10 μm thick solder paste to the surface of the copper strip on the upper substrate, and use a die bonder to bond the P-type thermoelectric particles and N-type thermoelectric particles according to... Figure 1 The method involves precisely attaching the particles to the corresponding positions of the current-guiding copper strip, and then using a reflow soldering process to achieve a stable bond between the particles and the upper substrate.

[0027] (5) Upper and lower layer stacking and sealing: Apply 10 μm thick solder paste to the metal end face of the upper P / N particle, and align and press the upper and lower substrates together. Figure 1 In the diagram, the green dashed block P represents the lower layer P particles, the yellow dashed block N represents the lower layer N particles, the green solid block P represents the upper layer P particles, the yellow solid block N represents the upper layer N particles, and the black part is the ceramic plate guiding copper strip (partially obscured by P / N particles). The placement angle is controlled, requiring the upper layer particles to be stacked along the length of the particles and perpendicular to the lower layer particles. Then, the device is fabricated by reflow soldering.

[0028] In this embodiment, the dual-level device includes upper and lower substrates, with three interface thermal resistances: the lower substrate and the lower die, the lower die and the upper die, and the upper die and the upper substrate. Compared with the four interface thermal resistances of conventional dual-level devices (lower substrate and lower die, lower die and middle substrate, middle substrate and upper die, and upper die and upper substrate), the interface thermal resistance can be reduced by about 30%.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A two-stage thermoelectric cooling device with a stepless ceramic substrate, characterized in that, The dual-stage thermoelectric cooling device includes a lower substrate, an upper substrate, a conductive copper sheet, a first-stage thermoelectric particle array, and a second-stage thermoelectric particle array. The first-stage thermoelectric particle array is composed of P-type thermoelectric particles and N-type thermoelectric particles arranged alternately. The second-stage thermoelectric particles are also composed of P-type thermoelectric particles and N-type thermoelectric particles arranged alternately. The lower substrate is sequentially connected to a conductive copper sheet and a first-stage thermoelectric particle array; the upper substrate is sequentially connected to a conductive copper sheet and a second-stage thermoelectric particle array. The first-stage thermoelectric particle array and the second-stage thermoelectric particle array are arranged vertically opposite each other. Between the two arrays, P-type thermoelectric particles and N-type thermoelectric particles are stacked in a crisscross pattern. The P-type thermoelectric particles of the first-stage array and the N-type thermoelectric particles of the second-stage array are alternately bonded, and the P-type thermoelectric particles of the second-stage array and the N-type thermoelectric particles of the first-stage array are alternately bonded. The electrical connection between the two arrays is achieved by welding the metallized contact surfaces of the thermoelectric particles.

2. The two-stage thermoelectric refrigeration device according to claim 1, characterized in that, The upper and lower substrates are made of highly thermally conductive insulating materials.

3. The two-stage thermoelectric refrigeration device according to claim 2, characterized in that, The high thermal conductivity insulating material is aluminum oxide, aluminum nitride, or beryllium oxide.

4. The two-stage thermoelectric refrigeration device according to claim 1, characterized in that, Both the P-type and N-type thermoelectric particles are made of bismuth telluride-based thermoelectric materials.

5. The two-stage thermoelectric refrigeration device according to claim 4, characterized in that, Both the upper and lower surfaces of the P-type and N-type thermoelectric particles are coated with nickel and copper metal films.

6. The two-stage thermoelectric cooling device according to claim 5, characterized in that, The thickness of the nickel metal film is 1 μm to 20 μm; the thickness of the copper metal film is 1 μm to 100 μm.

7. The two-stage thermoelectric refrigeration device according to claim 1, characterized in that, The dimensions of the P-type thermoelectric particles and the N-type thermoelectric particles satisfy the condition that the length is greater than twice the width.

8. The two-stage thermoelectric cooling device according to any one of claims 1 to 7, characterized in that, One side of the upper substrate is fixed with a conductive copper sheet using DBC, AMB, DPC, or adhesive bonding processes, and the second-stage thermoelectric particle array is connected to the conductive copper sheet by welding; one side of the lower substrate is fixed with a conductive copper sheet using DBC, AMB, DPC, or adhesive bonding processes, and the first-stage thermoelectric particle array is connected to the conductive copper sheet by welding.

9. A method for preparing a two-stage thermoelectric refrigeration device according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: S1. Cut the upper and lower substrates to the same size and fix the conductive copper sheet; prepare P-type bismuth telluride-based thermoelectric materials using zone melting, hot pressing, hot extrusion, or plasma discharge sintering; cut the P-type bismuth telluride-based thermoelectric materials into wafers using an inner circle dicing machine or a multi-wire dicing machine; deposit nickel and copper metal films on both sides of the wafers using electroplating, chemical plating, or magnetron sputtering processes; finally, cut the P-type thermoelectric particles using a dicing machine or a multi-wire dicing machine; prepare N-type thermoelectric particles using the same method. S2. Apply solder paste to the surface of the copper strip on the lower substrate. Use a die bonder to attach P-type and N-type thermoelectric particles to the corresponding positions on the copper strip. Through reflow soldering, the particles are firmly soldered to the lower substrate to form the first-stage thermoelectric particle array. Apply solder paste to the surface of the copper strip on the upper substrate. Use a die bonder to attach P-type and N-type thermoelectric particles to the corresponding positions on the copper strip. Through reflow soldering, the particles are firmly soldered to the upper substrate to form the second-stage thermoelectric particle array. S3. Apply solder paste to the surface of the first-stage thermoelectric particle array or the second-stage thermoelectric particle array, press and fix the upper and lower substrates together, and stack the first-stage thermoelectric particle array and the second-stage thermoelectric particle array alternately. Reflow soldering completes the device fabrication.

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