Three-dimensionally integrated flexible thermoelectric refrigeration device and method of manufacturing the same

Abstract

The application discloses a three-dimensional integrated flexible thermoelectric refrigeration device and a preparation method thereof, and belongs to the technical field of thermoelectric device preparation. The island-bridge interconnection process is used to release all the stress in the serpentine line when the device is stretched, and the extensible performance of the device is given. The interlayer filling process is used to realize the interlayer thermal interconnection of the multilayer device. The multilayer device stacking process is used to control the power and the number of thermoelectric arms in different layers by layering, so that the cold end of the upper layer device is used to dissipate heat for the hot end of the lower layer device, and the traditional metal heat dissipation fin is replaced. Meanwhile, the multilayer device also improves the utilization efficiency of air cooling, and greatly improves the overall refrigeration performance of the device.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric device fabrication technology, specifically relating to a design method for three-dimensional integration of flexible thermoelectric refrigeration devices. Background Technology

[0002] Flexible electronics is a new and transformative technology that has emerged in recent years. It involves depositing electronic materials and devices on flexible substrates, thereby endowing traditional electronic materials and devices with novel properties such as bendability, foldability, and stretchability. In recent years, with the research on new materials and processes, it has been vigorously developed in academic and industrial circles at home and abroad.

[0003] Personalized temperature regulation plays a crucial role not only in human comfort and health but also significantly impacts energy consumption. Thermoelectric devices are well-suited for this purpose. Combining thermoelectric devices with flexible substrates to create wearable thermoelectric coolers can provide personalized temperature control and manage various physical conditions such as sclerosis, fever, burns, and neurological disorders. Furthermore, these devices can offer greater comfort for outdoor workers.

[0004] However, current flexible thermoelectric coolers have problems such as requiring a large heat sink to achieve active cooling, low thermal conductivity of flexible films resulting in poor heat conduction and heat dissipation capabilities, and being flexible but not stretchable.

[0005] Therefore, researching a three-dimensional integration method for flexible thermoelectric devices with stretchable and high cooling performance is of great significance for the practical application of wearable thermoelectric cooling devices. Summary of the Invention

[0006] To address the problem of poor flexibility in wearable thermoelectric cooling devices, which necessitate large heat sinks for active cooling, this invention aims to provide a three-dimensional integrated design method for flexible thermoelectric cooling devices. This invention designs a wearable thermoelectric cooling device structure that achieves thermal interconnection of multiple layers through three-dimensional integration technology. The cooling performance is enhanced by controlling the power of different layers. Furthermore, through island-bridge interconnection technology, stress is primarily released within the island-bridge structure when the device is subjected to tensile forces, endowing the device with stretchability and achieving high flexibility.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A three-dimensional integrated flexible thermoelectric cooling device is characterized in that the thermoelectric device is a multi-layered, sequentially stacked cooler, with each layer having the same structure. The cooler includes: an N-type thermoelectric arm, a P-type thermoelectric arm, an upper circuit, and a lower circuit. The N-type and P-type thermoelectric arms are located between the upper and lower circuits. The bottom layer of the lower circuit is a substrate, on which metal patches are arrayed. All adjacent metal patches are grouped in pairs, and the two metal patches within a group are connected by an "S"-shaped metal wire. An N-type or P-type thermoelectric arm is welded onto each metal patch. The N-type and P-type thermoelectric arms are cylindrical and stand upright on the metal patches. The electric arms and P-type thermoelectric arms are arranged in an alternating row configuration. The upper circuit and the lower circuit are mirror images of each other, but the adjacent metal patches connected by the "S"-shaped metal wires in the upper and lower circuits are different. The adjacent metal patches are connected by the "S"-shaped metal wires, so that all the N-type thermoelectric arms and P-type thermoelectric arms are connected in series. The lower circuit of the upper cooler and the upper circuit of the adjacent lower cooler are provided with through holes at corresponding positions. The through holes do not contact the metal patches and the "S"-shaped metal wires. A heat-conducting block is installed in the through hole. The heat-conducting block protrudes from the upper surface of the lower circuit of the upper cooler and the lower surface of the upper circuit of the adjacent lower cooler.

[0009] Furthermore, the three-dimensional integrated flexible thermoelectric refrigeration device includes two layers of coolers.

[0010] Furthermore, all thermoelectric arms in the upper cooler and the adjacent lower cooler are aligned one by one, so that the cooling end of the upper cooler corresponds to the hot end of the adjacent lower cooler.

[0011] Furthermore, a protective layer is provided in both the upper and lower circuits to encapsulate metal patches and "S"-shaped metal wires; the lower circuit of the upper cooler and the upper circuit of the adjacent lower cooler are bonded together with uncured silicone, and the shape is formed after the silicone cures.

[0012] Furthermore, the number of thermoelectric arms in the upper cooler is greater than the number of thermoelectric arms in the lower cooler.

[0013] A method for fabricating a three-dimensional integrated flexible thermoelectric refrigeration device includes the following steps:

[0014] Step 1. Spray silicone release agent onto glass slides and heat and dry them on an oven. Prepare high thermal conductivity ECOFLEX by combining ECOFLEX with 2ALN powder. Spin coat the ECOFLEX onto a spin coater and heat it on an oven to solidify it into a thin film.

[0015] Step 2. Apply water-soluble adhesive tape to one side of the copper foil with polyimide to fix it in place. Engrav the designed island bridge circuit on a UV laser micro-engraving machine. The island bridge circuit consists of metal patches and "S"-shaped metal lines connecting adjacent metal patches. Transfer the engraved island bridge circuit onto the surface of the film prepared in Step 1. Heat the film on an oven to improve the adhesion between the polyimide and the film. Wash the heated film under clean water to dissolve the water-soluble adhesive tape on the copper surface, resulting in a film with the island bridge circuit transferred onto its surface.

[0016] Step 3. Weld thermoelectric arms onto the island structure on which the island bridge circuit film was transferred in Step 2. Apply uncured ECOFLEX mixed adhesive dots between the thermoelectric arms. Spin coat the adhesive on a spin coater and heat it on a baking rack to form a sandwich structure with ECOFLEX sandwiching the island bridge circuit. Then weld the complementary circuit to the other end of the thermoelectric arm so that the two circuits are connected through the thermoelectric arm to form a circuit.

[0017] Step 4. Encapsulate the thin film from Step 1 onto the exposed circuit that was soldered in Step 3, and demold to complete the fabrication of the first layer of the device;

[0018] Step 5. On the demolded device film, use an ultraviolet laser engraving machine to engrave a groove matrix and fill it with interlayer filler;

[0019] Step 6. Spin-coat a layer of ECOFLEX and ALN mixture onto the surface of the interlayer filler film. Before the ECOFLEX solidifies, encapsulate the other prepared thermoelectric device together according to Step 4. Use the alignment process to align the upper and lower thermoelectric arms to complete the fabrication of the two-layer device. Repeat the above steps to complete the fabrication of the multilayer device.

[0020] Further, in step 1, the silicone release agent is heated and dried at 240°C for 10 minutes on a drying rack, the weight ratio of ALN to ECFLEX is 20% to 30%, the spin coating speed is 400 r / min for 2 minutes, the drying rack temperature is 100°C, and the heating time is 5 minutes; in step 2, the drying rack temperature is 120°C, and the heating time is 10 minutes.

[0021] Further, in step 3, the spin coater speed is 400 r / min for 2 minutes, the heating table temperature is 100°C, and the heating time is 5 minutes. The soldering method in step 3 involves applying solder paste to the island structure in the circuit, placing the P-type and N-type thermoelectric arms crosswise on the island structure, and heating at 230°C for 15 minutes on the heating table to complete the soldering of the thermoelectric arms to the island structure. Then, the complementary circuit with solder paste applied to its surface is placed on top of the thermoelectric arm, and a hot air gun at 300°C is used to melt the solder paste, completing the soldering of the complementary circuit.

[0022] Furthermore, the specific process of thin film encapsulation in step 4 is as follows: the unsolidified ECOFLEX and ALN mixture is spin-coated onto the thin film prepared in step 1 at 400 r / min for 2 min. Before solidification, the exposed circuit side that was soldered in step 3 is pressed onto the thin film, and the film is heated on a 100° baking table for 5 min to solidify the ECOFLEX.

[0023] Furthermore, the alignment method in step 6 is as follows: an alignment pattern is engraved on a thin film using an ultraviolet micro-engraving machine, and the thermoelectric arm alignment is completed by aligning the pattern.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] This invention provides a three-dimensional integrated design method for flexible thermoelectric cooling devices, which enables wearable flexible thermoelectric cooling devices to have stretchability. Furthermore, multi-layer devices improve their cooling performance through interlayer thermal interconnection and hierarchical adjustment of power and the number of thermoelectric arms. This three-dimensional integration method is applicable to multi-purpose flexible devices. Attached Figure Description

[0026] Figure 1 This is a diagram showing the circuit and thermoelectric arm welding in Example 1.

[0027] Figure 2 This is a diagram showing the welding of the complementary circuit and the thermoelectric arm in Example 1.

[0028] Figure 3 This is a detailed diagram of the sandwich structure in Example 1.

[0029] Figure 4 The diagram shows the flexible three-dimensional integrated thermoelectric cooling device fabricated according to the present invention (two layers as an example).

[0030] Figure 5 This is a performance comparison chart of single-layer and double-layer devices, as shown in Example 1. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0032] The mechanism of this invention is as follows: by using island-bridge interconnect technology, all stress is released in the serpentine line when the device is stretched, giving the device ductility; by using interlayer filling technology, interlayer thermal interconnection of multilayer devices is achieved; by using multilayer device stacking technology, by controlling the power and the number of thermoelectric arms in different layers, the cold end of the upper device can dissipate heat to the hot end of the lower device, replacing the traditional metal heat sink. At the same time, multilayer devices also improve the utilization efficiency of air cooling, greatly improving the overall cooling performance of the device.

[0033] Island-bridge interconnection process, interlayer filling process, multilayer device stacking process, and independent layer control;

[0034] The island-bridge interconnection process includes multiple thermoelectric materials and interconnection circuits; an island-shaped structure is designed as the electrode of the thermoelectric material and welded to one end of the thermoelectric material. The electrodes of the N-type thermoelectric material and the P-type thermoelectric material are connected by a designed serpentine circuit to achieve circuit interconnection. The serpentine circuit serves as the main stress relief structure when the device is stretched.

[0035] The multilayer device stacking process includes multiple sets of thermoelectric pairs connected by island-bridge interconnection technology, and a substrate elastomeric silicone film; wherein the elastomeric silicone film serves as the substrate, a layer of unsolidified silicone is coated on its surface, and it is encapsulated at one end of the thermoelectric interconnection structure, so that the island-bridge interconnection structure is encapsulated within the silicone film; alignment patterns are designed on the film, and the stacking of multilayer thermoelectric interconnection structures is achieved through the alignment structure.

[0036] The interlayer filling process includes a substrate silicone film and an interlayer filler. By designing alignment patterns on the film, a groove is made at the position of the film between two pairs of thermocouples using laser etching technology. The interlayer filler is filled into the groove, and an uncured silicone film is coated on top. After the silicone film solidifies, the encapsulation is completed, and thermal interconnection is achieved.

[0037] The layered independent control includes controlling the number of thermoelectric arms and the driving power of each layer; by controlling the number and power of thermoelectric arms of each layer, the cooling capacity of the upper layer is increased, and the cooling end of the upper layer thermoelectric device dissipates heat to the hot end of the lower layer device, replacing the traditional metal heat sink. At the same time, the multi-layer device also improves the utilization efficiency of air cooling and greatly enhances the overall cooling performance of the device.

[0038] Example 1

[0039] Step 1. A high thermal conductivity ECOFLEX thin film is prepared by combining ECOFLEX with 2ALN powder. The specific implementation plan is as follows: a silicone release agent is sprayed onto a glass slide and heated on a 240°C oven for 10 minutes. 20% ALN and EC FLEX by weight are stirred and mixed evenly. The mixed ECOFLEX is then applied onto the glass slide. The glass slide coated with ECOFLEX is placed on a spin coater and spin-coated at 400 r / min for 2 minutes. The glass slide is then removed and heated on a 100°C oven for 5 minutes to complete the fabrication of the high thermal conductivity thin film.

[0040] Step 2. Apply water-soluble adhesive tape to one side of the copper foil with polyimide to fix it in place. Engrave the designed island bridge circuit on a UV laser micro-engraving machine. Transfer the engraved island bridge circuit to the surface of the film prepared in Step 1. Heat it on a 120°C baking table for 10 minutes to improve the adhesion between the polyimide and the film. Wash the heated film under clean water to dissolve the water-soluble adhesive tape on the copper surface, and obtain a film with the island bridge circuit transferred to its surface.

[0041] Step 3. Weld thermoelectric arms onto the island structure on which the island bridge circuit film has been transferred in Step 2, such as... Figure 1 As shown, uncured ECOFLEX mixed adhesive is dotted into the gaps between the thermoelectric arms. After spin coating at 400 rpm for 2 minutes on a spin coater, it is heated on a 100°C oven for 5 minutes, forming a sandwich structure of ECOFLEX sandwiching the island bridge circuit. The complementary circuit is then soldered to the other end of the thermoelectric arm, connecting the two circuits into a single circuit via the thermoelectric arm. Figure 2 As shown. The soldering method involves applying solder paste to the island structure in the circuit, placing the P-type and N-type thermoelectric arms crosswise on the island structure, and heating at 230°C for 15 minutes on a heating platform to complete the soldering of the thermoelectric arms to the island structure. Then, the complementary circuit, with solder paste applied to its surface, is placed on top of the thermoelectric arms, and a hot air gun at 300°C is used to melt the solder paste, completing the soldering of the complementary circuit.

[0042] Step 4. Encapsulate the thin film from Step 1 onto the exposed circuitry soldered in Step 3 to form a sandwich structure, such as... Figure 3 As shown. Demolding and removal from the glass sheet completes the fabrication of the first layer of the device. The specific process of thin-film encapsulation is as follows: The unsolidified ECOFLEX and ALN mixture is spin-coated at 400 r / min for 2 min onto the thin film prepared in step one. Before solidification, the exposed circuit side that was soldered in step 3 is pressed onto the thin film, and the film is heated on a 100°C baking table for 5 min to solidify the ECOFLEX.

[0043] Step 5. On the demolded device film, use an ultraviolet laser engraving machine to engrave a groove matrix and fill it with a high thermal conductivity filler.

[0044] Step 6. Spin-coat a layer of ECOFLEX and ALN mixture onto the surface of the film containing the interlayer filler. Before the ECOFLEX solidifies, encapsulate the other prepared thermoelectric device together as in Step 4. Use a UV micro-engraving machine to engrave the alignment pattern onto the film. Align the upper and lower thermoelectric arms using an alignment process to complete the fabrication of the two-layer device. Repeat the above steps to complete the fabrication of the multilayer device. The three-dimensional structure diagram of the multilayer thermoelectric cooling device prepared in this embodiment is shown below. Figure 4 As shown,

[0045] Comparative Example 1

[0046] A single-layer thermoelectric cooling device and a double-layer thermoelectric cooling device were prepared according to the steps of Example 1. The single-layer device was supplied with a 0.25A constant current source. The double-layer device was supplied with a 0.3A constant current source on the lower layer and a 0.25A constant current source on the upper layer. Both devices were simultaneously cooled by airflow at a speed of 1.7 m / s. The current supplied to each device was the current that achieved the best cooling performance. Increasing the current further would cause the hot end temperature of the thermoelectric device to transfer to the cold end, resulting in an increase in the cold end temperature.

[0047] The performance graph is as follows Figure 4 As shown, it is clear that at a room temperature of 25°C, the single-layer device can only cool down by 2°C, reaching 23°C. In contrast, the double-layer device can cool down by 6°C, reaching 19°C, representing a nearly three-fold performance improvement.

Claims

1. A three-dimensional integrated flexible thermoelectric cooling device, characterized in that, This thermoelectric cooling device is a multi-layered, stacked cooler, with each layer having the same structure. The cooler includes: an N-type thermoelectric arm, a P-type thermoelectric arm, an upper circuit, and a lower circuit. The N-type and P-type thermoelectric arms are located between the upper and lower circuits. The bottom layer of the lower circuit is a substrate, on which metal patches are arrayed. All adjacent metal patches are grouped in pairs, and the two patches within a group are connected by an "S"-shaped metal wire. An N-type or P-type thermoelectric arm is soldered onto each metal patch. The N-type and P-type thermoelectric arms are cylindrical and stand upright on the metal patches. The entire structure of the N-type and P-type thermoelectric arms... The circuits are arranged in a staggered, column-by-column configuration. The upper and lower circuits are mirror images of each other, but the adjacent metal patches connected by the "S"-shaped metal wires in the upper and lower circuits are different. The adjacent metal patches are connected by the "S"-shaped metal wires, so that all the N-type and P-type thermoelectric arms are connected in series. The lower circuit of the upper cooler and the upper circuit of the adjacent lower cooler are provided with through holes at corresponding positions. The through holes do not contact the metal patches and the "S"-shaped metal wires. A heat-conducting block is installed in the through hole, and the heat-conducting block protrudes from the upper surface of the lower circuit of the upper cooler and the lower surface of the upper circuit of the adjacent lower cooler.

2. The three-dimensional integrated flexible thermoelectric cooling device as described in claim 1, characterized in that, The three-dimensional integrated flexible thermoelectric refrigeration device includes two layers of coolers.

3. The three-dimensional integrated flexible thermoelectric cooling device as described in claim 1, characterized in that, All thermoelectric arms in the upper cooler and the adjacent lower cooler are aligned one by one, so that the cooling end of the upper cooler corresponds to the hot end of the adjacent lower cooler.

4. The three-dimensional integrated flexible thermoelectric cooling device as described in claim 1, characterized in that, Both the upper and lower circuits are provided with a protective layer, which encapsulates metal patches and "S"-shaped metal wires; the lower circuit of the upper cooler and the upper circuit of the adjacent lower cooler are bonded together with uncured silicone, and the shape is formed after the silicone cures.

5. The three-dimensional integrated flexible thermoelectric cooling device as described in claim 1, characterized in that, The number of thermoelectric arms in the upper cooler is greater than the number of thermoelectric arms in the lower cooler.

6. The method for fabricating a three-dimensional integrated flexible thermoelectric refrigeration device as described in claim 1, comprising the following steps: Step 1. Spray silicone release agent onto glass slides, heat and dry on an oven table, prepare high thermal conductivity ECOFLEX by combining ECOFLEX with ALN powder, spin coat on a spin coater, and heat on an oven table to solidify ECOFLEX into a thin film. Step 2. Apply water-soluble adhesive tape to one side of the copper foil with polyimide to fix it in place. Engrav the designed island bridge circuit on a UV laser micro-engraving machine. The island bridge circuit consists of metal patches and "S"-shaped metal lines connecting adjacent metal patches. Transfer the engraved island bridge circuit onto the surface of the film prepared in Step 1. Heat the film on an oven to improve the adhesion between the polyimide and the film. Wash the heated film under clean water to dissolve the water-soluble adhesive tape on the copper surface, resulting in a film with the island bridge circuit transferred onto its surface. Step 3. Weld thermoelectric arms onto the island structure on which the island bridge circuit film was transferred in Step 2. Apply uncured ECOFLEX mixed adhesive dots between the thermoelectric arms. Spin coat the adhesive on a spin coater and heat it on a baking rack to form a sandwich structure with ECOFLEX sandwiching the island bridge circuit. Then weld complementary circuits to the other end of the thermoelectric arms so that the two circuits are connected through the thermoelectric arms to form a circuit. Step 4. Encapsulate the thin film from Step 1 onto the exposed circuit that was soldered in Step 3, and demold to complete the fabrication of the first layer of the device; Step 5. On the demolded device film, use a UV laser engraving machine to engrave a groove matrix and fill it with interlayer filler; Step 6. Spin-coat a layer of ECOFLEX and ALN mixture onto the surface of the interlayer filler film. Before the ECOFLEX solidifies, encapsulate the other prepared thermoelectric device together as in Step 4. Align the upper and lower thermoelectric arms using an alignment process to complete the fabrication of the two-layer device. Repeat the above steps to complete the fabrication of the multilayer device.

7. The method for fabricating a three-dimensional integrated flexible thermoelectric refrigeration device as described in claim 6, characterized in that, In step 1, the silicone release agent is heated and dried at 240°C for 10 minutes on an oven. The weight ratio of ALN to ECFLEX is 20% to 30%. The spin coating speed is 400 r / min for 2 minutes. The oven temperature is 100°C and the heating time is 5 minutes. In step 2, the oven temperature is 120°C and the heating time is 10 minutes.

8. The method for fabricating a three-dimensional integrated flexible thermoelectric refrigeration device as described in claim 6, characterized in that, In step 3, the spin coater speed is 400 r / min for 2 min, the baking table temperature is 100°C, and the heating time is 5 min. The welding method in step 3 is to apply solder paste to the island structure in the circuit, place the P-type and N-type thermoelectric arms crosswise on the island structure, and heat at 230°C for 15 min on the heating table to complete the welding of the thermoelectric arms and the island structure. Then, place the complementary circuit with solder paste applied to its surface on the top of the thermoelectric arm, and use a hot air gun to blow 300°C hot air to melt the solder paste to complete the welding of the complementary circuit.

9. The method for fabricating a three-dimensional integrated flexible thermoelectric refrigeration device as described in claim 6, characterized in that, The specific process of thin film encapsulation in step 4 is as follows: spin-coating the unsolidified ECOFLEX and ALN mixture onto the thin film prepared in step 1 at 400 r / min for 2 min. Before solidification, press the exposed circuit side that was soldered in step 3 onto the thin film and heat it on a 100° oven for 5 min to solidify the ECOFLEX.

10. The method for fabricating a three-dimensional integrated flexible thermoelectric refrigeration device as described in claim 6, characterized in that, The alignment method in step 6 is as follows: use an ultraviolet micro-engraving machine to engrave the alignment pattern on the film, and complete the thermoelectric arm alignment by aligning the pattern.

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