thermoelectric element

Abstract

A thermoelectric element according to one embodiment of the present disclosure includes a first substrate, a first insulating layer provided on the first substrate, a second insulating layer provided on the first insulating layer, a first electrode provided on the second insulating layer, and a semiconductor structure provided on the first electrode, wherein the first insulating layer includes a concave-convex portion, a partial region of the first electrode is buried in the second insulating layer, the second insulating layer includes a concave portion that is concave in a direction from a side surface of the first electrode toward the first insulating layer, and the concave portion overlaps the concave-convex portion perpendicularly.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a thermoelectric element, and more particularly to a substrate and an insulation layer of a thermoelectric element. BACKGROUND

[0002] The thermoelectric phenomenon is a phenomenon that occurs due to the movement of electrons and holes in a material, meaning direct energy conversion between heat and electricity.

[0003] A thermoelectric element is a general term for an element in which the thermoelectric phenomenon is used, and has a structure in which a P-type thermoelectric material and an N-type thermoelectric material are joined between metal electrodes to form a pair of PN junctions.

[0004] Thermoelectric elements can be classified into elements using a change in resistance with temperature, elements using the Seebeck effect in which electromotive force is generated due to a temperature difference, and elements using the Peltier effect in which heat absorption or heating occurs due to an electric current.

[0005] Thermoelectric elements are being applied in various ways to home appliances, electronic components, communication components, etc. For example, thermoelectric elements can be applied to cooling devices, heating devices, power generation devices, etc. Thus, the demand for thermoelectric performance of thermoelectric elements is gradually increasing.

[0006] A thermoelectric element includes a substrate, electrodes, and thermoelectric legs, in which a plurality of thermoelectric legs are disposed between an upper substrate and a lower substrate, a plurality of upper electrodes are disposed between the upper substrate and the plurality of thermoelectric legs, and a plurality of lower electrodes are disposed between the plurality of thermoelectric legs and the lower substrate.

[0007] There are increasing attempts to use a metal substrate to improve the heat transfer performance of a thermoelectric element.

[0008] In general, a thermoelectric element can be manufactured according to a process of sequentially stacking electrodes and thermoelectric legs on a metal substrate prepared in advance. When a metal substrate is used, an advantageous effect can be obtained in terms of heat conduction, but when the metal substrate is used for a long time, there is a problem of reduced reliability due to low withstand voltage.

[0009] In order to solve such a problem, attempts have been made to improve the withstand voltage by anodizing the surface of an aluminum substrate, but there is a problem in that the anodized metal substrate is difficult to combine with the electrodes.

[0010] Thus, there is a need for a thermoelectric element having improved heat conduction performance as well as improved withstand voltage performance and combination performance. SUMMARY

[0011] TECHNICAL PROBLEM

[0012] The present disclosure aims to provide a structure of a substrate and an insulating layer of a thermoelectric element in which thermal conductivity, withstand voltage, and bonding properties are improved.

[0013] Technical Solution

[0014] According to an aspect of the present disclosure, there is provided a thermoelectric element including a first substrate, a first insulating layer disposed on the first substrate, a second insulating layer disposed on the first insulating layer, a first electrode disposed on the second insulating layer, and a semiconductor structure disposed on the first electrode, wherein the first insulating layer includes an uneven portion, a partial area of the first electrode is embedded in the second insulating layer, the second insulating layer includes a concave portion that is concave in a direction from a side surface of the first electrode toward the first insulating layer, and the concave portion vertically overlaps the uneven portion.

[0015] At least one of a component and elasticity of the first insulating layer can be different from at least one of a component and elasticity of the second insulating layer, and a withstand voltage of the first insulating layer can be greater than a withstand voltage of the second insulating layer, and a thermal conductivity of the second insulating layer can be greater than a thermal conductivity of the first insulating layer.

[0016] The first insulating layer can include a composite material containing silicon and aluminum, and the second insulating layer can be a resin layer made of a resin component containing at least one of an epoxy resin and a silicone resin and an inorganic filler.

[0017] The composite material can include at least one of an Al-Si bond, an Al-O-Si bond, a Si-O bond, an Al-Si-O bond, and an Al-O bond.

[0018] The uneven portion can be formed on a surface of the first insulating layer, which contacts the second insulating layer, among two surfaces of the first insulating layer, and have a surface roughness (Ra) of 0.1 μm or more.

[0019] The first insulating layer can have a thickness of 20 μm to 35 μm.

[0020] The second insulating layer can have a thickness of 20 μm to 70 μm.

[0021] The concave portion can be disposed between two adjacent first electrodes, and a thickness of the second insulating layer can decrease from a side surface of each of the two adjacent first electrodes toward a central region between the two adjacent first electrodes.

[0022] A thickness of the second insulating layer disposed on a side surface of the first electrode can be greater than a thickness of the second insulating layer disposed on a lower surface of the first electrode.

[0023] The thermoelectric element can further include a second electrode disposed on the semiconductor structure, a third insulating layer disposed on the second electrode, and a second substrate disposed on the third insulating layer, wherein at least one of the first substrate and the second substrate can be made of at least one of aluminum, copper, an aluminum alloy, and a copper alloy.

[0024] Advantageous Effects

[0025] According to embodiments of the present disclosure, a thermoelectric element having excellent performance and high reliability can be provided. In particular, according to embodiments of the present disclosure, a thermoelectric element having improved thermal conductivity performance, as well as improved withstand voltage performance and bonding performance can be provided. According to embodiments of the present disclosure, a thermoelectric element having high bonding force between a substrate and an electrode, as well as high bonding force between a substrate and a heat spreader can be provided.

[0026] The thermoelectric element according to embodiments of the present disclosure can be applied to large-size applications such as vehicles, ships, steel plants, incinerators, etc., as well as small-size applications. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a cross-sectional view of a thermoelectric element;

[0028] Figure 2 is a perspective view of a thermoelectric element;

[0029] Figure 3 is a perspective view of a thermoelectric element including a sealing member;

[0030] Figure 4 is an exploded perspective view of a thermoelectric element including a sealing member;

[0031] Figure 5 is a cross-sectional view of a thermoelectric element according to an embodiment of the present disclosure;

[0032] Figure 6 is a cross-sectional view of a thermoelectric element according to another embodiment of the present disclosure;

[0033] Figure 7 is a cross-sectional view of a thermoelectric element according to yet another embodiment of the present disclosure;

[0034] Figures 8a to 8c shows results of measuring surface roughness of an insulating layer according to an example; and

[0035] Figures 9a to 9c shows results of measuring surface roughness of an insulating layer according to a comparative example. DETAILED DESCRIPTION

[0036] Exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0037] However, the technical spirit of the disclosure is not limited to some embodiments to be described and can be embodied in various forms, and one or more elements in the embodiments can be selectively combined and replaced to be used within the scope of the technical spirit of the disclosure.

[0038] Further, the terms used in the embodiments of the present application, including technical and scientific terms, are interpreted as having meanings that are commonly understood by those skilled in the art unless they are specifically defined and described, and the terms generally used, such as terms defined in a dictionary, can be interpreted to have meanings that are consistent with the context of the related technology.

[0039] Further, the terms used in the embodiments of the present application, including technical and scientific terms, are interpreted as having meanings that are commonly understood by those skilled in the art unless they are specifically defined and described, and the terms generally used, such as terms defined in a dictionary, can be interpreted to have meanings that are consistent with the context of the related technology.

[0040] In the present specification, unless the context clearly indicates otherwise, the singular form includes the plural form, and in the case of describing "at least one of A, B, and C (or one or more of A, B, and C)," this can include at least one of all combinations that can be combined with A, B, and C.

[0041] In addition, terms such as first, second, A, B, (a), (b), etc. can be used to describe elements of the embodiments of the disclosure.

[0042] These terms are provided only to distinguish the elements from other elements, and the nature, sequence, order, etc. of the elements are not limited by the terms.

[0043] In addition, when an element is described as being "connected", "coupled", or "linked" to another element, the element can not only include a case where it is directly connected, coupled, or linked to the other element, but also include a case where it is connected, coupled, or linked to the other element through yet another element between them.

[0044] Further, when an element is described as being formed "on (over)" or "under" another element, the terms "on (over)" or "under" include a case where the two elements are in direct contact with each other, or a case where one or more elements are disposed between the two elements (indirectly). In addition, when an element is referred to as being disposed "on or under" another element, such a description can include a case where the element is disposed on the upper side or the lower side with respect to the other element.

[0045] Figure 1 is a cross-sectional view of a thermoelectric element, Figure 2 is a perspective view of a thermoelectric element. Figure 3 is a perspective view of a thermoelectric element including a sealing member, Figure 4 is an exploded perspective view of a thermoelectric element including a sealing member. is a cross-sectional view of a thermoelectric element, Figure 2 is a perspective view of a thermoelectric element. Figure 3 is a perspective view of a thermoelectric element including a sealing member, Figure 4 is an exploded perspective view of a thermoelectric element including a sealing member. is a cross-sectional view of a thermoelectric element, Figure 2 is a perspective view of a thermoelectric element. Figure 3 is a perspective view of a thermoelectric element including a sealing member, Figure 4 is an exploded perspective view of a thermoelectric element including a sealing member.

[0046] Reference Figure 1 and Figure 2 The thermoelectric element 100 includes a lower substrate 110, a lower electrode 120, P-type thermoelectric legs 130, N-type thermoelectric legs 140, an upper electrode 150, and an upper substrate 160.

[0047] The lower electrode 120 is disposed between the lower substrate 110 and the lower bottom surfaces of the P-type thermoelectric legs 130 and the N-type thermoelectric legs 140, and the upper electrode 150 is disposed between the upper substrate 160 and the upper surfaces of the P-type thermoelectric legs 130 and the N-type thermoelectric legs 140. Thus, the plurality of P-type thermoelectric legs 130 and the plurality of N-type thermoelectric legs 140 are electrically connected by the lower electrode 120 and the upper electrode 150. A pair of the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 disposed between the lower electrode 120 and the upper electrode 150 and electrically connected to each other can form a cell.

[0048] For example, when a voltage is applied between the lower electrode 120 and the upper electrode 150 by the lead wires 181 and 182, the substrate of the P-type thermoelectric leg 130 to which the current flows from the N-type thermoelectric leg 140 due to the Peltier effect can absorb heat and thus serve as a cooling component, and the substrate of the N-type thermoelectric leg 140 to which the current flows from the P-type thermoelectric leg 130 can be heated and thus serve as a heating component. Alternatively, when a temperature difference is provided between the lower electrode 120 and the upper electrode 150, charges in the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 move due to the Seebeck effect, so electricity can be generated.

[0049] Here, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be bismuth telluride (Bi-Te) based thermoelectric legs with bismuth (Bi) and tellurium (Te) as main raw materials. The P-type thermoelectric leg 130 can be a Bi-Te based thermoelectric leg including at least one of antimony (Sb), nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), tellurium (Te), bismuth (Bi), and indium (In). For example, the P-type thermoelectric leg 130 can include Bi-Sb-Te based main raw materials in a range of 99 to 99.999 wt% and a material containing at least one of Ni, Al, Cu, Ag, Pb, B, Ga, and In in a range of 0.001 to 1 wt% based on a total weight of 100 wt%. The N-type thermoelectric leg 140 can be a Bi-Te based thermoelectric leg including at least one of selenium (Se), Ni, Al, Cu, Ag, Pb, B, Ga, Te, Bi, and In. For example, the N-type thermoelectric leg 140 can include Bi-Se-Te based main raw materials in a range of 99 to 99.999 wt% and a material containing at least one of Ni, Al, Cu, Ag, Pb, B, Ga, and In in a range of 0.001 to 1 wt% based on a total weight of 100 wt%.

[0050] Thus, the thermoelectric leg can be referred to herein as a semiconductor structure, a semiconductor device, a semiconductor material layer, a thermoelectric structure, a thermoelectric material layer, a thermoelectric semiconductor structure, a thermoelectric semiconductor device, a thermoelectric semiconductor material layer, etc.

[0051] The P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be formed in a bulk type or a stacked type. In general, the P-type thermoelectric leg 130 of the bulk type or the N-type thermoelectric leg 140 of the bulk type can be obtained by performing a heat treatment on a thermoelectric material to manufacture an ingot, crushing and sieving the ingot to obtain a powder for a thermoelectric leg, sintering the powder, and cutting the sintered body. Here, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be a polycrystalline thermoelectric leg. To obtain the polycrystalline thermoelectric leg, the powder for the thermoelectric leg can be compressed at a pressure of 100 MPa to 200 MPa when sintering. For example, when sintering the P-type thermoelectric leg 130, the powder for the thermoelectric leg can be sintered at a pressure of 100 to 150 MPa, preferably 110 to 140 MPa, more preferably 120 to 130 MPa. In addition, when sintering the N-type thermoelectric leg 140, the powder for the thermoelectric leg can be sintered at a pressure of 150 to 200 MPa, preferably 160 to 195 MPa, more preferably 170 to 190 MPa. As described above, when the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 are polycrystalline thermoelectric legs, the strength of each of the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be improved. The P-type thermoelectric leg 130 of the stacked type or the N-type thermoelectric leg 140 of the stacked type can be obtained by coating a sheet-shaped substrate with a paste including a thermoelectric material to form a unit member, stacking the unit members, and cutting the stacked unit members.

[0052] In this case, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 pair can have the same shape and volume, or can have different shapes and volumes. For example, since the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 have different conductive properties, the height or cross-sectional area of the N-type thermoelectric leg 140 can be formed differently from that of the P-type thermoelectric leg 130.

[0053] Here, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 can have a cylindrical shape, a polygonal prism shape, an elliptical cylindrical shape, or the like.

[0054] Alternatively, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 can have a stacked structure. For example, the P-type thermoelectric leg or the N-type thermoelectric leg can be formed by stacking a plurality of structures each having a sheet-shaped substrate coated with a semiconductor material, and then cutting the plurality of structures. Thus, it can be possible to prevent material loss and improve the conductive properties. Each structure can further include a conductive layer having an open pattern, thereby improving adhesion between the structures, reducing thermal conductivity, and improving electrical conductivity.

[0055] Alternatively, the P-type thermoelectric arm 130 or the N-type thermoelectric arm 140 can be formed such that a cross-sectional area thereof is different in one thermoelectric arm. For example, in one thermoelectric arm, the cross-sectional areas of two end portions respectively arranged to face the electrodes can be formed to be greater than the cross-sectional area between the two end portions. Thus, a large temperature difference can be formed between the two end portions, and thus, the thermoelectric efficiency can be improved.

[0056] The performance of the thermoelectric element according to one embodiment of the present disclosure can be represented by a figure of merit ZT. The figure of merit ZT can be represented by Equation 1.

[0057] [Equation 1]

[0058]

[0059] where α is a Seebeck coefficient [V / K], σ is an electrical conductivity [S / m], α 2 σ is a power factor [W / mK 2 ]. In addition, T is a temperature, and k is a thermal conductivity [W / mK]. k can be represented as a·cp·p, where a is a thermal diffusivity [cm 2 / S], cp is a specific heat [J / gK], and p is a density [g / cm 3 ].

[0060] In order to obtain the figure of merit of the thermoelectric element, a Z value [V / K] is measured using a Z meter, and the figure of merit ZT can be calculated using the measured Z value.

[0061] Here, the lower electrode 120 disposed between the lower substrate 110 and the P-type thermoelectric arm 130 and the N-type thermoelectric arm 140, and the upper electrode 150 disposed between the upper substrate 160 and the P-type thermoelectric arm 130 and the N-type thermoelectric arm 140 can include at least one of Cu, Ag, Al, and Ni, and have a thickness of 0.01 mm to 0.3 mm. When the thickness of the lower electrode 120 or the upper electrode 150 is less than 0.01 mm, the function thereof as an electrode is reduced, and thus, the electrical conductivity can be degraded, and when the thickness thereof exceeds 0.3 mm, the electrical conductivity efficiency can be degraded due to an increase in resistance.

[0062] In addition, the lower substrate 110 and the upper substrate 160, which face each other, can be metal substrates, and can have a thickness of 0.1 mm to 1.5 mm. When the thickness of the metal substrate is less than 0.1 mm or more than 1.5 mm, a heat radiation characteristic or a thermal conductivity can excessively increase, thereby possibly reducing reliability of the thermoelectric element. In addition, when the lower substrate 110 and the upper substrate 160 are metal substrates, an insulating layer 170 can be further formed between the lower substrate 110 and the lower electrode 120 and between the upper substrate 160 and the upper electrode 150. The insulating layer 170 can include a material having a thermal conductivity of 1 to 20 W / mK.

[0063] In this case, the lower substrate 110 and the upper substrate 160 can be formed to have different sizes. For example, a volume, a thickness, or an area of one of the lower substrate 110 and the upper substrate 160 can be formed to be greater than a volume, a thickness, or an area of the other. Thus, heat absorption performance or heat dissipation performance of the thermoelectric element can be improved. Preferably, at least one of a volume, a thickness, or an area of the lower substrate 110 can be formed to be greater than a volume, a thickness, or an area of the upper substrate 160. Here, in a case where the lower substrate 110 is disposed in a high temperature region of the Seebeck effect, the lower substrate 110 is used as a heating region of the Peltier effect, or a sealing member (to be described below) for protecting the thermoelectric module from an external environment is disposed on the lower substrate 110, at least one of a volume, a thickness, or an area of the lower substrate 110 can be greater than a volume, a thickness, or an area of the upper substrate 160. In this case, an area of the lower substrate 110 can be formed in a range of 1.2 to 5 times an area of the upper substrate 160. When the area of the lower substrate 110 is formed to be less than 1.2 times the area of the upper substrate 160, an effect of improving heat transfer efficiency is not great, and when the area of the lower substrate 110 is formed to be greater than 5 times the area of the upper substrate 160, heat transfer efficiency is significantly reduced, and a basic shape of the thermoelectric module can be difficult to maintain.

[0064] In addition, a heat dissipation pattern, for example, an irregular pattern, can be formed on a surface of at least one of the lower substrate 110 and the upper substrate 160. Thus, heat dissipation performance of the thermoelectric element can be improved. In a case where the irregular pattern is formed on a surface in contact with the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140, bonding between the thermoelectric leg and the substrate can also be improved. The thermoelectric element 100 includes the lower substrate 110, the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, the upper electrode 150, and the upper substrate 160.

[0065] As Figures 3 to 4As shown in the middle, the sealing member 190 can be disposed between the lower substrate 110 and the upper substrate 160. The sealing member can be disposed on one side surface of the lower electrode 120, the P-type thermoelectric arm 130, the N-type thermoelectric arm 140, and the upper electrode 150 between the lower substrate 110 and the upper substrate 160. Thus, the lower electrode 120, the P-type thermoelectric arm 130, the N-type thermoelectric arm 140, and the upper electrode 150 can be sealed from external moisture, heat, contaminants, etc. Here, the sealing member 190 can include a sealing case 192 disposed at a predetermined distance from the outermost sides of the plurality of lower electrodes 120, the plurality of P-type thermoelectric arms 130 and the plurality of N-type thermoelectric arms 140, and the plurality of upper electrodes 150, a sealing material 194 disposed between the sealing case 192 and the lower substrate 110, and a sealing material 196 disposed between the sealing case 192 and the upper substrate 160. As described above, the sealing case 192 can be in contact with the lower substrate 110 and the upper substrate 160 through the sealing materials 194 and 196. Thus, it is possible to prevent the problem in which heat conduction occurs through the sealing case 192 when the sealing case 192 is in direct contact with the lower substrate 110 and the upper substrate 160, and as a result, the temperature difference between the lower substrate 110 and the upper substrate 160 is reduced. Here, the sealing materials 194 and 196 can include at least one of an epoxy resin and a silicone resin, or can include a tape having both sides on which at least one of an epoxy resin and a silicone resin is applied. The sealing materials 194 and 194 can function to hermetically seal between the sealing case 192 and the lower substrate 110 and between the sealing case 192 and the upper substrate 160, can improve the sealing effect of the lower electrode 120, the P-type thermoelectric arm 130, the N-type thermoelectric arm 140, and the upper electrode 150, and can be mixed with a decorative material, a decorative layer, a waterproof material, a waterproof layer, etc. Here, the sealing material 194 that seals between the sealing case 192 and the lower substrate 110 can be disposed on the upper surface of the lower substrate 110, and the sealing material 196 that seals between the sealing case 192 and the upper substrate 160 can be disposed on the side surface of the upper substrate 160. To this end, the area of the lower substrate 110 can be greater than the area of the upper substrate 160. Meanwhile, a guide groove G for guiding the lead wires 180 and 182 connected to the electrodes can be formed in the sealing case 192. To this end, the sealing case 192 can be an injection-molded product made of plastic or the like, and can be used together with a sealing cover plate. However, the above description of the sealing member is merely exemplary, and the sealing member can be modified in various forms. Although not shown in the drawings, a heat insulating material can be further included to surround the sealing member. Alternatively, the sealing member can include a heat insulating component.

[0066] Meanwhile, the P-type thermoelectric arm 130 and the N-type thermoelectric arm 140 can have Figure 1 A and Figure 1the structure shown in B. Referring to Figure 1 A, the thermoelectric arms 130 and 140 can include thermoelectric material layers 132 and 142, first plating layers 134-1 and 144-1 stacked on one surface of the thermoelectric material layers 132 and 142, and second plating layers 134-2 and 144-2 stacked on the other surface (opposite to the one surface) of the thermoelectric material layers 132 and 142, respectively. Alternatively, referring to Figure 1 B, the thermoelectric arms 130 and 140 can include thermoelectric material layers 132 and 142, first plating layers 134-1 and 144-1 stacked on one surface of the thermoelectric material layers 132 and 142, second plating layers 134-2 and 144-2 stacked on the other surface (opposite to the one surface) of the thermoelectric material layers 132 and 142, first buffer layers 136-1 and 146-1 disposed between the thermoelectric material layers 132 and 142 and the first plating layers 134-1 and 144-1, respectively, and second buffer layers 136-2 and 146-2 disposed between the thermoelectric material layers 132 and 142 and the second plating layers 134-2 and 144-2, respectively. Alternatively, the thermoelectric arms 130 and 140 can further include metal layers stacked between the lower substrate 110 and each of the first plating layers 134-1 and 144-1, and between the upper substrate 160 and each of the second plating layers 134-2 and 144-2.

[0067] Here, the thermoelectric material layers 132 and 142 can include Bi and Te as a semiconductor material. The thermoelectric material layers 132 and 142 can have the same material or shape as the above-described P-type thermoelectric arm 130 or N-type thermoelectric arm 140. When the thermoelectric material layers 132 and 142 are polycrystalline, the bonding force between the thermoelectric material layers 132 and 142, the first buffer layers 136-1 and 146-1, and the first plating layers 134-1 and 144-1, and the bonding force between the thermoelectric material layers 132 and 142, the second buffer layers 136-2 and 146-2, and the second plating layers 134-2 and 144-2 can be enhanced. Thus, even when the thermoelectric element 100 is applied to an application in which vibration occurs (e.g., a vehicle, etc.), the problem of the first plating layer 134-1 or 144-1 and the second plating layer 134-2 or 144-2 being separated from the P-type thermoelectric arm 130 or N-type thermoelectric arm 140 and thus carbonizing can be prevented, thereby improving the durability and reliability of the thermoelectric element 100.

[0068] In addition, the metal layer can be formed of one selected from Cu, a copper alloy, Al, and an aluminum alloy, and can have a thickness of 0.1 to 0.5 mm, and preferably 0.2 to 0.3 mm.

[0069] Next, each of the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 can include at least one of Ni, Sn, Ti, Fe, Sb, Cr, and Mo, and can have a thickness of 1 to 20 µm, preferably 1 to 10 µm. The first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 prevent a reaction between Bi or Te, which is a semiconductor material of the thermoelectric material layers 132 and 142, and the metal layers, so that a performance decrease of the thermoelectric element can be prevented, and oxidation of the metal layers can also be prevented.

[0070] Here, the first buffer layers 136-1 and 146-1 can be respectively disposed between the thermoelectric material layers 132 and 142 and the first plating layers 134-1 and 144-1, and the second buffer layers 136-2 and 146-2 can be respectively disposed between the thermoelectric material layers 132 and 142 and the second plating layers 134-2 and 144-2. In this case, each of the first buffer layers 136-1 and 146-1 and the second buffer layers 136-2 and 146-2 can include at least one of Ni-Te, Sn-Te, Ti-Te, Fe-Te, Sb-Te, Cr-Te, and Mo-Te. According to an embodiment of the present disclosure, when the first buffer layers 136-1 and 146-1 including Te are respectively disposed between the thermoelectric material layers 132 and 142 and the first plating layers 134-1 and 144-1, and the second buffer layers 136-2 and 146-2 including Te are respectively disposed between the thermoelectric material layers 132 and 142 and the second plating layers 134-2 or 144-2, Te in the thermoelectric material layers 132 and 142 can be prevented from diffusing into the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2. Thus, a problem of an increase in resistance in the thermoelectric material layers due to a Bi-rich region can be prevented.

[0071] Although the terms "lower substrate 110", "lower electrode 120", "upper electrode 150", and "upper substrate 160" are used above, they are arbitrarily called "upper" and "lower" to facilitate understanding and convenience of explanation, and thus it can be understood that the positions can be reversed such that the lower substrate 110 and the lower electrode 120 are disposed on the upper side, and the upper electrode 150 and the upper substrate 160 can be disposed on the lower side.

[0072] Figure 5 is a cross-sectional view of a thermoelectric element according to another embodiment of the present disclosure, Figure 6 is a cross-sectional view of a thermoelectric element according to another embodiment of the present disclosure, Figure 7 is a cross-sectional view of a thermoelectric element according to another embodiment of the present disclosure. Explanation will be omitted with respect to the above regardingFigures 1 to 4 The repeated description of the same content as described above.

[0073] Reference Figures 5 to 7 The thermoelectric element 300 according to an embodiment of the disclosure includes a first substrate 310, a first insulating layer 320 disposed on the first substrate 310, a second insulating layer 330 disposed on the first insulating layer 320, a plurality of first electrodes 340 disposed on the second insulating layer 330, a plurality of P-type thermoelectric legs 350 and a plurality of N-type thermoelectric legs 355 disposed on the plurality of first electrodes 340, a plurality of second electrodes 360 disposed on the plurality of P-type thermoelectric legs 350 and the plurality of N-type thermoelectric legs 355, a third insulating layer 370 disposed on the plurality of second electrodes 360, and a second substrate 380 disposed on the third insulating layer 370. Although not shown in the drawing, a heat sink can be further disposed on the first substrate 310 or the second substrate 380. Although not shown in the drawing, a sealing member can be further disposed between the first substrate 310 and the second substrate 380. Although not shown in the drawing, a power source can be connected to the first electrodes 340 or the second electrodes 360, and a lead wire can be drawn out through the insulating layers and the substrates or can be drawn out laterally on the substrates and the insulating layers.

[0074] Here, the first electrodes 340, the P-type thermoelectric legs 350, the N-type thermoelectric legs 355, and the second electrodes 360 can correspond to the lower electrodes 120, the P-type thermoelectric legs 130, the N-type thermoelectric legs 140, and the upper electrodes 150, respectively, described with reference to Figure 1 and Figure 2 The descriptions of the lower electrodes 120, the P-type thermoelectric legs 130, the N-type thermoelectric legs 140, and the upper electrodes 150 described with reference to Figure 1 and Figure 2 may be applied in the same or similar manner.

[0075] At least one of the first substrate 310 and the second substrate 380 can be made of at least one of aluminum, an aluminum alloy, copper, and a copper alloy. The first substrate 310 and the second substrate 380 can be made of different materials. For example, among the first substrate 310 and the second substrate 380, a substrate requiring higher withstand voltage performance can be formed of an aluminum substrate, and a substrate requiring higher thermal conductivity performance can be formed of a copper substrate.

[0076] The withstand voltage performance according to an embodiment of the disclosure can refer to a feature of maintaining 10 seconds without dielectric breakdown at an AC voltage of 2.5 kV and a current of 1 mA. In the present specification, the withstand voltage performance is measured by disposing an insulating layer on a substrate, connecting one terminal to the substrate, connecting the other terminal to nine points of the insulating layer, and testing whether the feature maintains 10 seconds without dielectric breakdown at an AC voltage of 2.5 kV and a current of 1 mA.

[0077] Meanwhile, according to embodiments of the present disclosure, a double-layered insulating layer can be provided between the first substrate 310 and the first electrode 340. That is, the first insulating layer 320 can be provided on the first substrate 310, the second insulating layer 330 can be provided on the first insulating layer 320, and the first electrode 340 can be provided on the second insulating layer 330. In this case, one surface of the first insulating layer 320 can be in direct contact with the first substrate 310, and the other surface of the first insulating layer 320 can be in direct contact with the second insulating layer 330. In addition, the second insulating layer 330 can be in direct contact with the first electrode 340.

[0078] Here, the first insulating layer 320 and the second insulating layer 330 can have different compositions and elasticity. That is, the first insulating layer 320 can be formed of a composition having insulating properties and thermal conductivity properties, and the second insulating layer 330 can be formed of a composition having bonding properties and thermal shock mitigation properties as well as insulating properties and thermal conductivity properties. Further, both the first insulating layer 320 and the second insulating layer 330 can have insulating properties and thermal conductivity properties, the withstand voltage properties of the first insulating layer 320 can be higher than those of the second insulating layer 330, and the thermal conductivity properties of the second insulating layer 330 can be higher than those of the first insulating layer 320. Here, the relatively high withstand voltage properties can mean that a characteristic is maintained for a relatively long time without dielectric breakdown under an AC voltage of 2.5 kV and a current of 1 mA.

[0079] To this end, the first insulating layer 320 can include a composite material including silicon and aluminum. Here, the composite material can be at least one of an oxide, a carbide, and a nitride including silicon and aluminum. For example, the composite material can include at least one of an Al-Si bond, an Al-O-Si bond, a Si-O bond, an Al-Si-O bond, and an Al-O bond. The composite material including at least one of the Al-Si bond, the Al-O-Si bond, the Si-O bond, the Al-Si-O bond, and the Al-O bond has excellent insulating properties, and thus high withstand voltage properties can be achieved. Alternatively, the composite material can be an oxide, a carbide, or a nitride further including titanium, zirconium, boron, zinc, or the like, as well as silicon and aluminum. To this end, the composite material can be obtained by mixing aluminum with at least one of an inorganic binder and an organic-inorganic hybrid binder and then heat-treating the mixture. The inorganic binder can include, for example, at least one of silicon dioxide (SiO2), a metal alkoxide, boron oxide (B2O3), and zinc oxide (ZnO2). The inorganic binder can be an inorganic particle and can function as a binder by dissolving or gelling when in contact with water. In this case, at least one of silicon dioxide (SiO2), a metal alkoxide, and boron oxide (B2O3) can be used to increase adhesion between aluminum or to the first insulating layer 320, and zinc oxide (ZnO2) can be used to increase the strength of the first insulating layer 320 and to increase the thermal conductivity.

[0080] Here, the composite material can be included in an amount of at least 80 wt%, preferably at least 85 wt%, and more preferably at least 90 wt% of the entire first insulating layer 320.

[0081] Here, the first insulating layer 320 can include an uneven portion. For example, a surface roughness Ra of 0.1 μm or more can be formed in the first insulating layer 320. The surface roughness can be formed by particles of the composite material protruding from the surface of the first insulating layer 320, and can be measured using a surface roughness measuring device. The surface roughness measuring device can be provided to measure a cross-sectional curve using a probe and to calculate the surface roughness using a peak line, a valley bottom line, an average line, and a reference length of the cross-sectional curve. In the present specification, the surface roughness can refer to an arithmetic mean roughness Ra obtained by a method of calculating a center line average. The arithmetic mean roughness Ra can be obtained by Equation 2 below.

[0082] [Equation 2]

[0083]

[0084] That is, when a cross-sectional curve obtained by a probe of a surface roughness measuring apparatus is extracted as much as a reference length L and expressed as a function (f(x)), an average line direction is set as an x-axis and a height direction is set as a y-axis, a value obtained by Equation 2 can be expressed in μm.

[0085] Here, the uneven portion of the first insulating layer 320 can be formed on a surface of the first insulating layer 320 which contacts the second insulating layer 330. As described above, when the surface roughness Ra of the first insulating layer 320 is 0.1 μm or more, the contact area with the second insulating layer 330 is widened, thereby improving the bonding strength between the first insulating layer 320 and the second insulating layer 330. In particular, as will be described below, when the second insulating layer 330 is formed of a resin layer, the resin layer of the second insulating layer 330 can penetrate between grooves formed by the surface roughness of the first insulating layer 320, so the bonding strength between the first insulating layer 320 and the second insulating layer 330 can be further improved.

[0086] Here, the first insulating layer 320 can be formed on the first substrate 310 by a wet process. Here, the wet process can be a spray coating process, a dip coating process, a screen printing process, etc. Thus, the thickness of the first insulating layer 320 can be easily controlled, and a composite material of various components can be applied.

[0087] According to an embodiment of the present disclosure, the first insulating layer 320 is made of a composite material containing silicon and aluminum and is formed by a wet process, so that the surface roughness can be formed to be 0.1 μm or more. Figures 8a to 8c is a graph showing results of measuring surface roughness of three samples in which the first insulating layer 320 is formed on an aluminum substrate, Figures 9a to 9c is a graph showing results of measuring surface roughness of three samples in which an aluminum substrate is subjected to an anodizing process. Reference Figures 8a to 8c and Figures 9a to 9c It can be seen that the surface roughness of the first insulating layer according to an embodiment of the present disclosure can be formed to be 0.1 μm or more.

[0088] Meanwhile, the second insulating layer 330 can be formed of a resin layer including at least one of an epoxy resin component containing an epoxy resin and an inorganic filler and a silicone resin component containing polydimethylsiloxane (PDMS). Thus, the second insulating layer 330 can improve the insulation, the bonding force, and the thermal conductivity between the first insulating layer 320 and the first electrode 340.

[0089] Here, the content of the inorganic filler can be 60 to 80 wt% of the resin layer. When the content of the inorganic filler is less than 60 wt%, the heat conduction effect can be reduced, and when the content of the inorganic filler is greater than 80 wt%, the inorganic filler can be difficult to uniformly disperse in the resin, and the resin layer can be easily broken.

[0090] In addition, the epoxy resin can include an epoxy compound and a curing agent. In this case, the curing agent can be included in a volume ratio of 1 to 10 with respect to the volume ratio of the epoxy compound of 10. Here, the epoxy compound can include at least one of a crystalline epoxy compound, an amorphous epoxy compound, and a silicone epoxy compound. The inorganic filler can include at least one of alumina and nitride. When the inorganic filler includes nitride, the content of the nitride can be 55 to 95 wt% of the inorganic filler, and more preferably 60 to 80 wt%. When the nitride is included in the above numerical range, the thermal conductivity and the bonding strength can be improved. Here, the nitride can include at least one of boron nitride and aluminum nitride.

[0091] In this case, the particle size D50 of the boron nitride aggregate can be in the range of 250 to 350 μm, and the particle size D50 of the alumina can be in the range of 10 to 30 μm. When the particle size D50 of the boron nitride aggregate and the particle size D50 of the alumina satisfy the above numerical range, the boron nitride aggregate and the alumina can be uniformly dispersed in the resin layer, and thus the entire resin layer can have uniform heat conduction effects and bonding properties.

[0092] When the second insulating layer 330 is a resin composition including a PDMS resin and alumina, the content (e.g., weight ratio) of silicon in the first insulating layer 320 can be greater than the content of silicon in the second insulating layer 330, and the content of aluminum in the second insulating layer 330 can be greater than the content of aluminum in the first insulating layer 320. Thus, the silicon in the first insulating layer 320 can mainly contribute to the improvement of the withstand voltage property, and the alumina in the second insulating layer 330 can mainly contribute to the improvement of the heat conduction property. Thus, although the first insulating layer 320 and the second insulating layer 330 both have insulating properties and heat conduction properties, the withstand voltage property of the first insulating layer 320 can be higher than that of the second insulating layer 330, and the heat conduction property of the second insulating layer 330 can be higher than that of the first insulating layer 320.

[0093] Meanwhile, the second insulating layer 330 can be formed by coating the first insulating layer 320 with a resin component in an uncured or semi-cured state, then disposing a plurality of the first electrodes 340 in advance, and then applying pressure. Thus, the resin component forming the second insulating layer 330 can penetrate into recesses due to the surface roughness Ra of the first insulating layer 320, thereby improving the bonding strength between the first insulating layer 320 and the second insulating layer 330. In addition, a portion of the side surfaces of the plurality of first electrodes 340 can be embedded in the second insulating layer 330. In this case, the height H1 of the side surfaces of the plurality of first electrodes 340 embedded in the second resin layer 330 can be 0.1 to 1.0 times, preferably 0.2 to 0.9 times, and more preferably 0.3 to 0.8 times the thickness H of the plurality of first electrodes 340. As described above, when a portion of the side surfaces of the plurality of first electrodes 340 is embedded in the second insulating layer 330, the contact area between the plurality of first electrodes 340 and the second insulating layer 330 is widened, and thus the heat transfer performance and the bonding strength between the plurality of first electrodes 340 and the second insulating layer 330 can be further improved. When the height H1 of the side surfaces of the plurality of first electrodes 340 embedded in the second insulating layer 330 is less than 0.1 times the thickness H of the plurality of first electrodes 340, it can be difficult to obtain sufficient heat transfer performance and bonding strength between the plurality of first electrodes 340 and the second insulating layer 330, and when the height H1 of the side surfaces of the plurality of first electrodes 340 embedded in the second insulating layer 330 exceeds 1.0 times the thickness H of the plurality of first electrodes 340, the second insulating layer 330 can rise above the plurality of first electrodes 340, and thus there is a possibility of electrical short-circuiting.

[0094] In more detail, the second insulating layer 330 can include a concave portion concaved from the side surface of the first electrode 340 toward the direction of the first insulating layer 320. In this case, the concave portion is disposed between two adjacent first electrodes 340, and the thickness of the second insulating layer 330 can decrease from the side surface of each of the two adjacent first electrodes 340 toward the central region between the two adjacent first electrodes 340. That is, the thickness of the second insulating layer 330 between the plurality of first electrodes 340 decreases from the side surface of each electrode toward the central region therebetween, such that the apex of the concave portion can have a smooth "V" shape. As such, the second insulating layer 330 between the plurality of first electrodes 340 has a varying thickness, and the height T2 of the region in direct contact with the side surface of the plurality of first electrodes 340 is the greatest, and the height T3 of the central region can be less than the height T2 of the region in direct contact with the side surface of the plurality of first electrodes 340. That is, the height T3 of the central region of the second insulating layer 330 between the plurality of first electrodes 340 can be the least in the second insulating layer 330 between the plurality of first electrodes 340. In addition, the height T1 of the second insulating layer 330 under the plurality of first electrodes 340 can be less than the height T3 of the central region of the second insulating layer 330 between the plurality of first electrodes 340. As such, since the second insulating layer 330 can be disposed on the lower surface of the first electrode 340 as well as the side surface of the first electrode 340, the contact area between the first electrode 340 and the second insulating layer 330 can increase, and the bonding force and heat transfer performance between the first electrode 340 and the second insulating layer 330 can improve. Here, the concave portion of the second insulating layer 330 can vertically overlap the uneven portion of the first insulating layer 320, and the concave portion of the second insulating layer 330 can be formed on the surface of the two surfaces of the second insulating layer 330 opposite to the surface bonded to the uneven portion of the first insulating layer 320. As such, an uneven portion corresponding to the uneven portion of the first insulating layer 320 can also be formed on the surface of the two surfaces of the second insulating layer 330 bonded to the uneven portion of the first insulating layer 320, such that the bonding force and heat transfer performance between the first insulating layer 320 and the second insulating layer 330 can improve.

[0095] Meanwhile, depending on the composition of the first insulating layer 320 and the second insulating layer 330, at least one of the hardness, the elastic modulus, the elongation, and the Young's modulus of the first insulating layer 320 and the second insulating layer 330 can vary, and thus the voltage resistance performance, the heat conduction performance, the bonding performance, the thermal shock mitigation performance, etc. can be controlled.

[0096] For example, the weight ratio of the composite material to the entire first insulating layer 320 can be greater than the weight ratio of the inorganic filler to the entire second insulating layer 330. As described above, the composite material can be a composite material containing silicon and aluminum, and more particularly, a composite material containing at least one of an oxide, a carbide, and a nitride. For example, the weight ratio of the composite material to the entire first insulating layer 320 can be greater than 80 wt%, and the weight ratio of the inorganic filler to the entire second insulating layer 330 can be 60 to 80 wt%. As described above, when the content of the composite material contained in the first insulating layer 320 is greater than the content of the ceramic particles contained in the second insulating layer 330, the hardness of the first insulating layer 320 can be greater than the hardness of the second insulating layer 330. Thus, the first insulating layer 320 can have both high withstand voltage properties and high thermal conductivity properties.

[0097] Thus, the second insulating layer 330 can have greater elasticity than the first insulating layer 320. Thus, the second insulating layer 330 can improve the bonding properties between the first insulating layer 320 and the first electrode 340, and can alleviate thermal shock when the thermoelectric element 300 is driven. Here, the elasticity can be expressed as tensile strength. For example, the tensile strength of the second insulating layer 330 can be in the range of 2 to 5 MPa, preferably 2.5 to 4.5 MPa, and more preferably 3 to 4 MPa, and the tensile strength of the first insulating layer 320 can be in the range of 10 MPa to 100 MPa, preferably 15 MPa to 90 MPa, and more preferably 20 MPa to 80 MPa.

[0098] Here, the thickness of the first insulating layer 320 can be in the range of 20 to 35 μm, and the thickness of the second insulating layer 330 can be in the range of 20 to 70 μm, preferably 30 to 60 μm, and more preferably 35 to 50 μm. In this case, the thickness of the second insulating layer 330 can be 1 to 3.5 times, preferably 1 to 3 times, and more preferably 1 to 2 times the thickness of the first insulating layer 320.

[0099] When the thickness of the first insulating layer 320 and the thickness of the second insulating layer 330 satisfy the above numerical ranges, the withstand voltage properties, the thermal conductivity properties, the bonding properties, and the thermal shock alleviating properties can be simultaneously obtained. In particular, when the thickness of the first insulating layer 320 is less than 20 μm, it is difficult to obtain high withstand voltage properties, and the first insulating layer 320 can be easily broken due to thermal expansion of the second insulating layer 330, and when the thickness of the first insulating layer 320 exceeds 35 μm, the thermal conductivity properties can be reduced.

[0100] The insulation layer 370 disposed on the second substrate 380 can have the same structure as the insulation layers 320 and 330 disposed on the first substrate 310. That is, the insulation layer 370 disposed on the second substrate 380 can include a third insulation layer 372 formed of a resin layer including at least one of an epoxy resin component and a silicone resin component, and a fourth insulation layer 374 formed of a composite material including silicon and aluminum.

[0101] In this case, the fourth insulation layer 374 can be in direct contact with the second substrate 380, and the third insulation layer 372 can be disposed between the fourth insulation layer 374 and the second electrode 360. Detailed descriptions of the third insulation layer 372 can be applied in the same manner as the second insulation layer 330, and detailed descriptions of the fourth insulation layer 374 can be applied in the same manner as the first insulation layer 320.

[0102] Alternatively, the third insulation layer 372 can be formed of a resin layer including at least one of an epoxy resin component and a silicone resin component, and the fourth insulation layer 374 can be formed of a resin layer including at least one of an epoxy resin component and a silicone resin component. In this case, the resin layer forming the third insulation layer 372 and the resin layer forming the fourth insulation layer 374 can have the same component or different components. Here, the different components can mean at least one of a type of resin, a content of resin, a type of inorganic filler, and a content of inorganic filler.

[0103] Meanwhile, a power source is generally connected to the electrode disposed at the cold side of the thermoelectric element 300, and thus the cold side can require higher withstand voltage performance than the hot side. In contrast, when the thermoelectric element 300 is driven, the hot side of the thermoelectric element 300 can be exposed to high temperature, for example, at least about 180 °C, and delamination between the electrode, the insulation layer, and the substrate due to different coefficients of thermal expansion between the electrode, the insulation layer, and the substrate can be an issue. Thus, higher thermal shock mitigation performance can be required at the hot side of the thermoelectric element 300 than at the cold side of the thermoelectric element 300. Thus, the structure of the insulation layer at the hot side can be different from the structure of the insulation layer at the cold side.

[0104] Hereinafter, descriptions will be made based on the assumption that the first substrate 310 is disposed at the cold side of the thermoelectric element 300 and the second substrate 380 is disposed at the hot side of the thermoelectric element 300.

[0105] With reference to Figure 6 , the thickness of the fourth insulation layer 374 at the second substrate 380 side can be less than the thickness of the first insulation layer 320 at the first substrate 310 side, and the thickness of the third insulation layer 372 at the second substrate 380 side can be greater than the thickness of the second insulation layer 330 at the first substrate 310 side. Alternatively, with reference to Figure 7The insulating layer at the first substrate 310 side can include a first insulating layer 320 and a second insulating layer 330, and the insulating layer 370 at the second substrate 380 side can be made only of a resin layer including at least one of an epoxy resin component and a silicone resin component.

[0106] Thus, the thermal shock alleviation performance of the hot side can be improved, and the possibility of delamination that can occur due to different coefficients of thermal expansion between the substrate and the hot side electrode can be minimized.

[0107] The thermoelectric element according to the embodiments of the disclosure can be applied to power generation devices, cooling devices, and heating devices. In more detail, the thermoelectric element according to the embodiments of the disclosure can be mainly applied to optical communication modules, sensors, medical devices, measuring devices, aerospace industries, refrigerators, cold water machines, vehicle ventilation seats, cup holders, washing machines, dryers, wine cellars, water purifiers, sensor power sources, thermoelectric piles, etc.

[0108] Here, examples in which the thermoelectric element according to the embodiments of the disclosure is applied to medical devices include a polymerase chain reaction (PCR) device. The PCR device is a device that amplifies deoxyribonucleic acid (DNA) to determine the DNA base sequence, and requires precise temperature control and thermal cycling. For this, a Peltier-based thermoelectric element can be applied.

[0109] Another example in which the thermoelectric element according to the embodiments of the disclosure is applied to medical devices includes a photodetector. Here, the photodetector includes an infrared / ultraviolet detector, a charge-coupled device (CCD) sensor, an X-ray detector, a thermoelectric thermal reference source (TTRS), etc. A Peltier-based thermoelectric element can be applied to cool the photodetector. Thus, it is possible to prevent wavelength variation, output reduction, and resolution reduction due to temperature increase in the photodetector.

[0110] Still other examples in which the thermoelectric element according to the embodiments of the disclosure is applied to medical devices include the immunological analysis field, the in-vitro diagnosis field, general temperature control and cooling systems, the physical therapy field, liquid cooling systems, the blood / plasma temperature control field, etc. Thus, accurate temperature control is possible.

[0111] Yet another example in which the thermoelectric element according to the embodiments of the disclosure is applied to medical devices includes an artificial heart. Thus, it is possible to supply power to the artificial heart.

[0112] Examples in which the thermoelectric element according to the embodiments of the disclosure is applied to aerospace industries include a star tracking system, a thermal imaging camera, an infrared / ultraviolet detector, a CCD sensor, a Hubble space telescope, a TTRS, etc. Thus, it is possible to maintain the temperature of an image sensor.

[0113] Other examples in which the thermoelectric element according to the embodiments of the present disclosure is applied to the aerospace industry include cooling devices, heaters, power generation devices, and the like.

[0114] In addition to the above description, the thermoelectric element according to the embodiments of the present disclosure can be applied to power generation, cooling, and heating in other industrial fields.

[0115] While exemplary embodiments of the present disclosure have been described above, it will be understood by those skilled in the art that various modifications and changes can be made thereto without departing from the scope and spirit of the concepts disclosed in the present disclosure, which are to be limited only by the scope of the appended claims.

Claims

1. A thermoelectric element, comprising: substrate; A first insulating layer is disposed on the substrate; A second insulating layer is disposed on the first insulating layer; An electrode, wherein the electrode is disposed on the second insulating layer; as well as A semiconductor structure disposed on the electrode. The upper surface of the second insulating layer includes a first recess on which the electrode is disposed and a second recess surrounding the first recess. The height between the second recessed lower surface and the substrate is greater than the height between the first recessed lower surface and the substrate. The thickness of the second insulating layer is greater than the thickness of the first insulating layer.

2. The thermoelectric element according to claim 1, wherein, A portion of the electrode is embedded in the first recess.

3. The thermoelectric element according to claim 2, wherein, The side surface of the electrode includes a first surface that contacts the first recess of the second insulating layer, and The height of the first surface is 0.1 to 0.9 times the thickness of the electrode.

4. The thermoelectric element according to claim 2, wherein, The highest height of the electrode is higher than the highest height of the second insulating layer relative to the substrate.

5. The thermoelectric element according to claim 1, wherein, The thickness of the first insulating layer is less than 35 μm, the thickness of the second insulating layer is greater than 35 μm, and the thickness of the electrode is greater than 10 μm.

6. The thermoelectric element according to claim 5, wherein, An uneven pattern is provided on the upper surface of the first insulating layer, and the lower surface of the second insulating layer includes an uneven pattern corresponding to the uneven pattern on the upper surface of the first insulating layer.

7. The thermoelectric element according to claim 6, wherein, The surface roughness of the uneven pattern disposed on the upper surface of the first insulating layer is 0.1 μm or greater.

8. The thermoelectric element according to claim 1, further comprising: Upper electrode, wherein the upper electrode is disposed on the semiconductor structure; A third insulating layer is disposed on the upper electrode; as well as An upper substrate is disposed on the third insulating layer.

9. The thermoelectric element according to claim 8, wherein, The thickness of the third insulating layer is greater than the thickness of the second insulating layer.

10. The thermoelectric element according to claim 8, wherein, The second recess overlaps perpendicularly with the upper electrode.

11. The thermoelectric element according to claim 10, wherein: The lower surface of the third insulating layer includes a third recess that is recessed toward the upper substrate, and The third recess overlaps perpendicularly with a portion of the second recess and the first recess.

12. A thermoelectric element, comprising: First substrate; A first insulating layer is disposed on the first substrate; A second insulating layer is disposed on the first insulating layer; A first electrode, wherein the first electrode is disposed on the second insulating layer; A semiconductor structure disposed on the first electrode. The second electrode is disposed on the semiconductor structure; A third insulating layer is disposed on the second electrode; as well as The second substrate is disposed on the third insulating layer. The upper surface of the second insulating layer includes a first recess on which the first electrode is disposed and a second recess surrounding the first recess. The third insulating layer includes a third recess on which the second electrode is disposed. The third recess of the third insulating layer perpendicularly overlaps with the second recess of the second insulating layer and a portion of the first recess of the second insulating layer, and The thickness of the third insulating layer is greater than the thickness of the first insulating layer.

13. The thermoelectric element according to claim 12, wherein, The side surface of the first electrode includes a first surface that makes first recessed contact with the second insulating layer, and The height of the first surface is 0.1 to 0.9 times the thickness of the first electrode.

14. The thermoelectric element according to claim 12, wherein, The highest height of the first electrode is higher than the highest height of the second insulating layer relative to the first substrate.

15. The thermoelectric element according to claim 14, wherein, The height between the second recessed lower surface and the first substrate is greater than the height between the first recessed lower surface and the first substrate.

16. The thermoelectric element according to claim 15, wherein: The first recess in the second insulating layer includes a side surface that contacts the side surface of the first electrode, and The first recessed lower surface of the second insulating layer corresponds to the lower surface of the first electrode.

17. The thermoelectric element according to claim 16, wherein: The second recess is disposed between the two first recesses and spaced apart from each other, and includes a curved surface with curvature. The region including the center between the two first recesses and each side surface includes the region of the curved surface closest to the first substrate.

18. The thermoelectric element according to claim 14, wherein, The thickness of the first insulating layer is less than 35 μm, the thickness of the second insulating layer is greater than 35 μm, and the thickness of the first electrode is greater than 10 μm.

19. The thermoelectric element according to claim 12, wherein: The upper surface of the first insulating layer includes an uneven pattern with a surface roughness of 0.1 μm or greater, and The thickness of the third insulating layer is greater than the thickness of the second insulating layer.

20. The thermoelectric element of claim 12, further comprising a fourth insulating layer disposed between the third insulating layer and the second substrate. in, The thickness of the third insulating layer is greater than the thickness of each of the first insulating layer, the second insulating layer, and the fourth insulating layer.

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