Thermoelectric elements

Abstract

A thermoelectric element according to one embodiment of the present invention includes a first insulating layer, a first substrate disposed on the first insulating layer, a second insulating layer disposed on the first substrate, a first electrode disposed on the second insulating layer, P-type thermoelectric legs and N-type thermoelectric legs disposed on the first electrode, second electrodes disposed on the P-type thermoelectric legs and N-type thermoelectric legs, a third insulating layer disposed on the second electrode, and a second substrate disposed on the third insulating layer, wherein the first insulating layer includes a first aluminum oxide layer, the first substrate is an aluminum substrate, and the second substrate is a copper substrate, the first substrate being a low-temperature part and the second substrate being a high-temperature part.

Description

[Technical field]

[0001] The present invention relates to thermoelectric devices, and more particularly to substrates and insulating layers of thermoelectric devices. [Background technology]

[0002] Thermoelectricity is a phenomenon that occurs due to the movement of electrons and holes inside a material, and refers to the direct energy conversion between heat and electricity.

[0003] A thermoelectric element is a general term for elements that utilize the thermoelectric phenomenon, 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 PN junction pair.

[0004] Thermoelectric elements can be classified into elements that use a change in electrical resistance due to temperature, elements that use the Seebeck effect, which is a phenomenon in which an electromotive force is generated due to a temperature difference, and elements that use the Peltier effect, which is a phenomenon in which heat is absorbed or generated due to an electric current.

[0005] Thermoelectric elements are widely used in home appliances, electronic components, communication components, etc. For example, thermoelectric elements can be used in cooling devices, heating devices, power generation devices, etc. Accordingly, the demand for thermoelectric performance of thermoelectric elements is increasing.

[0006] The thermoelectric element includes a substrate, electrodes and thermoelectric legs, with a plurality of thermoelectric legs disposed between an upper substrate and a lower substrate, a plurality of upper electrodes disposed between the plurality of thermoelectric legs and the upper substrate, and a plurality of lower electrodes disposed between the plurality of thermoelectric legs and the lower substrate.

[0007] There has been an increasing attempt to use metallic substrates to improve the heat transfer performance of thermoelectric devices.

[0008] Generally, a thermoelectric element is manufactured by sequentially laminating a resin layer, electrodes, and thermoelectric legs on a pre-installed metal substrate. When a metal substrate is used, it has an advantageous effect in terms of thermal conduction, but has a problem of low reliability over long-term use due to its low withstand voltage.

[0009] To solve these problems, there have been attempts to increase the withstand voltage by oxidizing the surface of the metal substrate. However, a heat sink must be bonded to the substrate on the high temperature side, and bonding between the oxidized metal substrate and the heat sink is difficult.

[0010] Accordingly, there is a need for a thermoelectric element that has improved not only thermal conductivity performance but also voltage resistance performance and bonding performance with a heat sink. Detailed Description of the Invention Summary of the Invention [Problem to be solved by the invention]

[0011] The technical problem to be solved by the present invention is to provide a substrate and insulating layer structure for a thermoelectric element which has improved thermal conductivity, voltage resistance and bonding performance with a heat sink. [Means for solving the problem]

[0012] A thermoelectric element according to one embodiment of the present invention includes a first insulating layer, a first substrate disposed on the first insulating layer, a second insulating layer disposed on the first substrate, a first electrode disposed on the second insulating layer, a P-type thermoelectric leg and an N-type thermoelectric leg disposed on the first electrode, a second electrode disposed on the P-type thermoelectric leg and the N-type thermoelectric leg, a third insulating layer disposed on the second electrode, and a second substrate disposed on the third insulating layer, wherein the first insulating layer includes a first aluminum oxide layer, the first substrate is an aluminum substrate, and the second substrate is a copper substrate, the first substrate being a low temperature portion and the second substrate being a high temperature portion.

[0013] The second insulating layer and the third insulating layer may each be made of a resin layer including at least one of an epoxy resin composition and a silicone resin composition.

[0014] The second insulating layer may have a thickness equal to or smaller than a thickness of the third insulating layer.

[0015] The second insulating layer may include a second aluminum oxide layer, and the third insulating layer may be a resin layer including at least one of an epoxy resin composition and a silicone resin composition.

[0016] The second insulating layer is disposed on the second aluminum oxide layer and may further include a resin layer including at least one of an epoxy resin composition and a silicone resin composition.

[0017] The resin layer included in the second insulating layer may have a thickness smaller than that of the second aluminum oxide layer and that of the third insulating layer.

[0018] At least one of the first aluminum oxide layer and the second aluminum oxide layer may be formed by anodizing an aluminum substrate.

[0019] At least one of the first aluminum oxide layer and the second aluminum oxide layer may extend along a side of the aluminum substrate and be connected to each other.

[0020] The sum of the thicknesses of the first and second insulating layers may be 80 μm or more.

[0021] The device may further include a heat sink disposed on the copper substrate.

[0022] There may be no oxide layer disposed between the copper substrate and the heat sink. Effect of the Invention

[0023] According to the embodiments of the present invention, a thermoelectric element having excellent performance and high reliability can be obtained. In particular, according to the embodiments of the present invention, a thermoelectric element having improved not only thermal conductivity but also voltage resistance and bonding performance with a heat sink can be obtained.

[0024] Furthermore, according to the embodiment of the present invention, a thermoelectric element that satisfies all the required performance differences between the low temperature portion and the high temperature portion can be obtained.

[0025] The thermoelectric device according to the embodiment of the present invention can be applied not only to small applications but also to large applications such as vehicles, ships, steelworks, and incinerators. [Brief description of the drawings]

[0026] [Figure 1] FIG. 2 is a cross-sectional view of a thermoelectric element. [Diagram 2] FIG. 2 is a perspective view of a thermoelectric element.

[0027] [Diagram 3] FIG. 2 is a perspective view of a thermoelectric element including a sealing member.

[0028] [Figure 4] FIG. 2 is an exploded perspective view of a thermoelectric element including a sealing member.

[0029] [Diagram 5] 1 is a cross-sectional view of a thermoelectric element according to an embodiment of the present invention.

[0030] [Figure 6] FIG. 4 is a cross-sectional view of a thermoelectric element according to another embodiment of the present invention.

[0031] [Figure 7] FIG. 11 is a cross-sectional view of a thermoelectric element according to still another embodiment of the present invention.

[0032] [Figure 8] FIG. 11 is a cross-sectional view according to still another embodiment of the present invention. [Figure 9] FIG. 11 is a cross-sectional view according to still another embodiment of the present invention.

[0033] [Figure 10] This is the result of simulating the withstand voltage depending on the thickness of the insulating layer.

[0034] [Figure 11] 13 shows the results of a simulation of changes in thermal resistance depending on the thickness of the insulating layer in the structures according to the comparative example, the second embodiment, and the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0036] However, the technical concept of the present invention is not limited to the described embodiments, but may be embodied in various different forms, and one or more of the components of the embodiments may be selectively combined or substituted within the scope of the technical concept of the present invention.

[0037] Furthermore, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted in a manner that is commonly understood by a person having ordinary knowledge in the technical field to which the present invention belongs, unless otherwise clearly defined and described, and commonly used terms, such as terms defined in a dictionary, may be interpreted in light of the contextual meaning of the relevant art.

[0038] Furthermore, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0039] In this specification, the singular can include the plural unless otherwise specified in the context, and when it is stated that "A and (and) at least one (or more) of B and C" it can include one or more of all possible combinations of A, B, and C.

[0040] In addition, terms such as first, second, A, B, (a), (b), etc. may be used in describing components of embodiments of the present invention.

[0041] Such terms are merely used to distinguish a component from other components, and are not intended to limit the nature, order, or sequence of the components.

[0042] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it includes not only cases where the component is directly coupled, coupled, or connected to the other component, but also cases where the component is "coupled," "coupled," or "connected" by yet another component between the component and the other component.

[0043] In addition, when described as being formed or disposed "above or below" each component, "above" or "below" includes not only the case where two components are in direct contact with each other, but also the case where one or more other components are formed or disposed between the two components. In addition, when described as "above or below," it can include not only the upper direction but also the lower direction based on one component.

[0044] Fig. 1 is a cross-sectional view of a thermoelectric element, Fig. 2 is a perspective view of the thermoelectric element, Fig. 3 is a perspective view of the thermoelectric element including a sealing member, and Fig. 4 is an exploded perspective view of the thermoelectric element including a sealing member.

[0045] 1 and 2, a thermoelectric device 100 includes a lower substrate 110 , a lower electrode 120 , a P-type thermoelectric leg 130 , an N-type thermoelectric leg 140 , an upper electrode 150 and an upper substrate 160 .

[0046] 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 bottom surfaces of the P-type thermoelectric legs 130 and the N-type thermoelectric legs 140. Accordingly, 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 legs 130 and the N-type thermoelectric legs 140 disposed and electrically connected between the lower electrode 120 and the upper electrode 150 may form a unit cell.

[0047] For example, when a voltage is applied to the lower electrode 120 and the upper electrode 150 through the lead wires 181, 182, the substrate in which a current flows from the P-type thermoelectric leg 130 to the N-type thermoelectric leg 140 due to the Peltier effect absorbs heat and acts as a cooling part, and the substrate in which a current flows from the N-type thermoelectric leg 140 to the P-type thermoelectric leg 130 is heated and can act as a heating part. Alternatively, when a temperature difference is applied to 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, generating electricity.

[0048] Here, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 may be bismuth telluride (Bi-Te)-based thermoelectric legs containing bismuth (Bi) and tellurium (Te) as main raw materials. The P-type thermoelectric leg 130 may be a bismuth telluride (Bi-Te)-based thermoelectric leg containing 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 may contain 99 to 99.999 wt% of Bi-Sb-Te as a main raw material with respect to a total weight of 100 wt%, and may contain at least one of nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), and indium (In) at 0.001 to 1 wt%. The N-type thermoelectric leg 140 may be a bismuth telluride (Bi-Te)-based thermoelectric leg containing at least one of selenium (Se), nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), tellurium (Te), bismuth (Bi), and indium (In). For example, the N-type thermoelectric leg 140 may contain 99 to 99.999 wt% of the main raw material Bi-Se-Te with respect to a total weight of 100 wt%, and may contain at least one of nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), and indium (In) with a weight of 0.001 to 1 wt%.

[0049] The P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 may be formed in a bulk type or a laminate type. In general, the bulk type P-type thermoelectric leg 130 or the bulk type N-type thermoelectric leg 140 may be obtained by heat treating a thermoelectric material to manufacture an ingot, crushing and sieving the ingot to obtain powder for the thermoelectric legs, sintering the powder, and cutting the sintered body. In this case, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 may be polycrystalline thermoelectric legs. For the polycrystalline thermoelectric legs, the powder for the thermoelectric legs may be compressed at 100 MPa to 200 MPa when sintering. For example, when sintering the P-type thermoelectric leg 130, the powder for the thermoelectric legs may be sintered at 100 MPa to 150 MPa, preferably 110 MPa to 140 MPa, and more preferably 120 MPa to 130 MPa. When sintering the N-type thermoelectric leg 130, the powder for the thermoelectric leg can be sintered at 150 to 200 MPa, preferably 160 to 195 MPa, and more preferably 170 to 190 MPa. In this manner, when the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 are polycrystalline thermoelectric legs, the strength of the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be increased. The stacked P-type thermoelectric leg 130 or the stacked N-type thermoelectric leg 140 can be obtained through a process of forming unit members by applying a paste containing a thermoelectric material onto a sheet-like substrate, and then stacking and cutting the unit members.

[0050] In this case, the pair of P-type thermoelectric legs 130 and N-type thermoelectric legs 140 may have the same shape and volume or may have different shapes and volumes. For example, since the P-type thermoelectric legs 130 and the N-type thermoelectric legs 140 have different electrical conduction characteristics, the height or cross-sectional area of ​​the N-type thermoelectric legs 140 may be formed to be different from the height or cross-sectional area of ​​the P-type thermoelectric legs 130.

[0051] In this case, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 may have a cylindrical shape, a polygonal column shape, an elliptical column shape, or the like.

[0052] Alternatively, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 may have a laminated structure. For example, the P-type thermoelectric leg or the N-type thermoelectric leg may be formed by laminating a plurality of structures in which a semiconductor material is applied to a sheet-like substrate, and then cutting the laminate. This can prevent material loss and improve electrical conductivity. Each structure may further include a conductive layer having an opening pattern, which can increase the adhesive strength between the structures, reduce thermal conductivity, and increase electrical conductivity.

[0053] Alternatively, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 may be formed to have different cross-sectional areas within one thermoelectric leg. For example, the cross-sectional area of ​​both ends arranged toward the electrodes within one thermoelectric leg may be formed to be larger than the cross-sectional area between the two ends. This can increase the temperature difference between the two ends, thereby increasing thermoelectric efficiency.

[0054] The performance of the thermoelectric device according to an embodiment of the present invention can be expressed by a thermoelectric figure of merit (ZT). The thermoelectric figure of merit (ZT) can be expressed as in Equation 1.

[0055] TIFF0007633946000001.tif10136

[0056] where α is the Seebeck coefficient [V / K], σ is the electrical conductivity [S / m], and α 2 σ is the power factor (PowerFactor, [W / mK 2 ]), where T is temperature and k is thermal conductivity [W / mK]. k can be expressed as a·cp·ρ, and a is thermal diffusivity [cm 2 / S], cp is the specific heat [J / gK], and ρ is the density [g / cm 3 ].

[0057] To obtain the thermoelectric figure of merit of a thermoelectric element, a z-meter is used to measure the Z value (V / K), and the measured Z value is used to calculate the thermoelectric figure of merit (ZT).

[0058] Here, the lower electrode 120 disposed between the lower substrate 110 and the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140, and the upper electrode 150 disposed between the upper substrate 160 and the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 may include at least one of copper (Cu), silver (Ag), aluminum (Al) and nickel (Ni) and have a thickness of 0.01 mm to 0.3 mm. If the thickness of the lower electrode 120 or the upper electrode 150 is less than 0.01 mm, the function as an electrode may be deteriorated and the electrical conduction performance may be reduced, and if the thickness exceeds 0.3 mm, the conduction efficiency may be reduced due to an increase in resistance.

[0059] The lower substrate 110 and the upper substrate 160 facing each other may be metal substrates, and may have a thickness of 0.1 mm to 1.5 mm. If the thickness of the metal substrate is less than 0.1 mm or exceeds 1.5 mm, the reliability of the thermoelectric element may be reduced since the heat dissipation characteristic or thermal conductivity may be excessively high. In addition, when the lower substrate 110 and the upper substrate 160 are metal substrates, an insulating layer 170 may be further formed between the lower substrate 110 and the lower electrode 120 and between the upper substrate 160 and the upper electrode 150, respectively. The insulating layer 170 may include a material having a thermal conductivity of 5 to 20 W / K.

[0060] At this time, the lower substrate 110 and the upper substrate 160 may be formed to have different sizes. For example, the volume, thickness or area of ​​one of the lower substrate 110 and the upper substrate 160 may be formed to be larger than the volume, thickness or area of ​​the other one. Accordingly, the heat absorption or heat dissipation performance of the thermoelectric element may be improved. Preferably, the volume, thickness or area of ​​the lower substrate 110 may be formed to be larger than at least one of the volume, thickness or area of ​​the upper substrate 160. At this time, when the lower substrate 110 is disposed in a high temperature region due to the Seebeck effect, when it is applied to a heat generation region due to the Peltier effect, or when a sealing member for protecting the thermoelectric module from the external environment described below is disposed on the lower substrate 110, at least one of the volume, thickness or area may be larger than that of the upper substrate 160. At this time, the area of ​​the lower substrate 110 may be formed to be 1.2 to 5 times larger than the area of ​​the upper substrate 160. If the area of ​​the lower substrate 110 is less than 1.2 times that of the upper substrate 160, the effect on improving heat transfer efficiency is not significant, and if it exceeds 5 times, the heat transfer efficiency may decrease significantly and it may be difficult to maintain the basic shape of the thermoelectric module.

[0061] In addition, a heat dissipation pattern, for example, a concave-convex pattern, may be formed on the surface of at least one of the lower substrate 110 and the upper substrate 160. Accordingly, the heat dissipation performance of the thermoelectric device may be improved. When the concave-convex pattern is formed on the surface in contact with the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140, the bonding characteristics between the thermoelectric legs and the substrate may be improved. The thermoelectric device 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.

[0062] 3 and 4, a sealing member 190 may be further disposed between the lower substrate 110 and the upper substrate 160. The sealing member may be disposed on the sides of the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the upper electrode 150 between the lower substrate 110 and the upper substrate 160. Accordingly, the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the upper electrode 150 may be sealed from external moisture, heat, contamination, and the like. Here, the sealing member 190 may include a sealing case 192 disposed at a predetermined distance from the outermost periphery of the plurality of lower electrodes 120, the outermost periphery of the plurality of P-type thermoelectric legs 130 and the plurality of N-type thermoelectric legs 140, and the outermost periphery of the plurality of upper electrodes 150, a sealant 194 disposed between the sealing case 192 and the lower substrate 110, and a sealant 196 disposed between the sealing case 192 and the upper substrate 160. In this manner, the sealing case 192 may contact the lower substrate 110 and the upper substrate 160 through the sealants 194 and 196. Accordingly, when the sealing case 192 directly contacts the lower substrate 110 and the upper substrate 160, heat conduction occurs through the sealing case 192, and as a result, a problem of a decrease in temperature difference between the lower substrate 110 and the upper substrate 160 may be prevented. Here, the sealant 194, 196 may include at least one of epoxy resin and silicone resin, or may include a tape coated with at least one of epoxy resin and silicone resin on both sides. The sealant 194, 194 serves to seal between the sealing case 192 and the lower substrate 110 and between the sealing case 192 and the upper substrate 160, and may enhance the sealing effect of the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the upper electrode 150, and may be mixed with a finishing material, a finishing layer, a waterproofing material, a waterproofing layer, etc. Here, the sealant 194 sealing between the sealing case 192 and the lower substrate 110 may be disposed on the upper surface of the lower substrate 110, and the sealant 196 sealing between the sealing case 192 and the upper substrate 160 may be disposed on the side of the upper substrate 160. For this reason, the area of ​​the lower substrate 110 may be larger than the area of ​​the upper substrate 160.Meanwhile, the sealing case 192 may be formed with a guide groove G for leading out the lead wires 180, 182 connected to the electrodes. For this purpose, the sealing case 192 may be an injection molded product made of plastic or the like, and may be mixed with a sealing cover. However, the above description of the sealing member is merely an example, and the sealing member may be modified into various forms. Although not shown, a heat insulating material may be further included to surround the sealing member. Alternatively, the sealing member may include a heat insulating component.

[0063] Meanwhile, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 may have the structure shown in Fig. 1(a) or 1(b). Referring to Fig. 1(a), the thermoelectric legs 130, 140 may include thermoelectric material layers 132, 142, first plating layers 134-1, 144-1 stacked on one side of the thermoelectric material layers 132, 142, and second plating layers 134-2, 144-2 stacked on the other side disposed opposite to the one side of the thermoelectric material layers 132, 142. Alternatively, referring to FIG. 1( b ), the thermoelectric legs 130, 140 may include thermoelectric material layers 132, 142, first plating layers 134-1, 144-1 stacked on one side of the thermoelectric material layers 132, 142, second plating layers 134-2, 144-2 stacked on the other side opposite the one side of the thermoelectric material layers 132, 142, and first buffer layers 136-1, 146-1 and second buffer layers 136-2, 146-2 respectively positioned between the thermoelectric material layers 132, 142 and the first plating layers 134-1, 144-1 and between the thermoelectric material layers 132, 142 and the second plating layers 134-2, 144-2, respectively. Alternatively, the thermoelectric legs 130, 140 may further include a metal layer laminated between the lower substrate 110 and the upper substrate 160, respectively, by forming the first plating layers 134-1, 144-1 and the second plating layers 134-2, 144-2, respectively.

[0064] Here, the thermoelectric material layers 132, 142 may include semiconductor materials such as bismuth (Bi) and tellurium (Te). The thermoelectric material layers 132, 142 may have the same material or shape as the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 described above. When the thermoelectric material layers 132, 142 are polycrystalline, the adhesive strength between the thermoelectric material layers 132, 142, the first buffer layers 136-1, 146-1, and the first plating layers 134-1, 144-1 and the adhesive strength between the thermoelectric material layers 132, 142, the second buffer layers 136-2, 146-2, and the second plating layers 134-2, 144-2 may be increased. As a result, even if the thermoelectric element 100 is applied to an application where vibration occurs, such as a vehicle, the first plating layers 134-1, 144-1 and the second plating layers 134-2, 144-2 can be prevented from detaching from the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 and carbonizing, thereby improving the durability and reliability of the thermoelectric element 100.

[0065] And, the metal layer may be selected from copper (Cu), copper alloy, aluminum (Al) and aluminum alloy, and may have a thickness of 0.1-0.5 mm, preferably 0.2-0.3 mm.

[0066] Next, the first plating layers 134-1, 144-1 and the second plating layers 134-2, 144-2 may each contain at least one of Ni, Sn, Ti, Fe, Sb, Cr, and Mo, and may have a thickness of 1 to 20 μm, preferably 1 to 10 μm. The first plating layers 134-1, 144-1 and the second plating layers 134-2, 144-2 prevent a reaction between the metal layer and the semiconductor material Bi or Te in the thermoelectric material layers 132, 142, and therefore can prevent not only a decrease in the performance of the thermoelectric element but also oxidation of the metal layer.

[0067] In this case, the first buffer layers 136-1, 146-1 and the second buffer layers 136-2, 146-2 may be disposed between the thermoelectric material layers 132, 142 and the first plating layers 134-1, 144-1 and between the thermoelectric material layers 132, 142 and the second plating layers 134-2, 144-2. In this case, the first buffer layers 136-1, 146-1 and the second buffer layers 136-2, 146-2 may include Te. For example, the first buffer layers 136-1, 146-1 and the second buffer layers 136-2, 146-2 may include at least one of Ni-Te, Sn-Te, Ti-Te, Fe-Te, Sb-Te, Cr-Te, and Mo-Te. According to the embodiment of the present invention, when the first buffer layers 136-1, 146-1 and the second buffer layers 136-2, 146-2 containing Te are disposed between the thermoelectric material layers 132, 142 and the first plating layers 134-1, 144-1 and the second plating layers 134-2, 144-2, it is possible to prevent the diffusion of Te in the thermoelectric material layers 132, 142 into the first plating layers 134-1, 144-1 and the second plating layers 134-2, 144-2. As a result, it is possible to prevent the problem of an increase in electrical resistance in the thermoelectric material layers due to a Bi-rich region.

[0068] In the above, the terms lower substrate 110, lower electrode 120, upper electrode 150 and upper substrate 160 are used, but these are merely arbitrarily referred to as upper and lower for ease of understanding and explanation, and the positions may be reversed so that the lower substrate 110 and lower electrode 120 are disposed at the upper part and the upper electrode 150 and upper substrate 160 are disposed at the lower part.

[0069] Fig. 5 is a cross-sectional view of a thermoelectric element according to one embodiment of the present invention, Fig. 6 is a cross-sectional view of a thermoelectric element according to another embodiment of the present invention, Fig. 7 is a cross-sectional view of a thermoelectric element according to yet another embodiment of the present invention, Fig. 8 is a cross-sectional view of yet another embodiment of the present invention, and Fig. 9 is a cross-sectional view of yet another embodiment of the present invention. Duplicate explanations of the same contents as those described in Figs. 1 to 4 will be omitted.

[0070] 5 to 7, a thermoelectric device 300 according to an embodiment of the present invention includes a first insulating layer 310, a first substrate 320 disposed on the first insulating layer 310, a second insulating layer 330 disposed on the first substrate 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. As shown in the drawings, a heat sink 390 may be further disposed on the second substrate 380. Although not shown in the drawings, a sealing member may be further disposed between the first substrate 320 and the second substrate 380.

[0071] Here, the first electrode 340, the P-type thermoelectric leg 350, the N-type thermoelectric leg 360, and the second electrode 370 may correspond to the upper electrode 150, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the lower electrode 120 described in Figures 1 and 2, respectively, and the contents described in Figures 1 and 2 may be applied in the same or similar manner.

[0072] Generally, since a power source is connected to an electrode disposed on the low temperature side of the thermoelectric element 300, the low temperature side may be required to have a higher withstand voltage performance than the high temperature side. Here, the (+) terminal and the (-) terminal are illustrated as being connected to the first electrode 340 and extending downward through the first insulating layer 310, the first substrate 320, and the second insulating layer 330, but are not limited thereto, and the (+) terminal and the (-) terminal may be connected to the first electrode 340 and then extended to the side on the first insulating layer 310, the first substrate 320, and the second insulating layer 330.

[0073] On the other hand, when the thermoelectric element 300 is operated, the high temperature side of the thermoelectric element 300 may be exposed to high temperatures, for example, about 180° C. or more, and peeling between the electrodes, the insulating layer, and the substrate may become an issue due to the different thermal expansion coefficients of the electrodes, the insulating layer, and the substrate. Accordingly, the high temperature side of the thermoelectric element 300 may be required to have higher thermal conductivity performance than the low temperature side. In particular, when a heat sink is further disposed on the substrate on the high temperature side of the thermoelectric element 300, the bonding strength between the substrate and the heat sink may also have a significant effect on the durability and reliability of the thermoelectric element 300.

[0074] Hereinafter, it will be assumed that the first substrate 320 is disposed on the low temperature side of the thermoelectric element 300, and the second substrate 380 is disposed on the high temperature side of the thermoelectric element 300. As shown in FIG.

[0075] According to an embodiment of the present invention, the first substrate 320 is an aluminum substrate, and the second substrate 380 is a copper substrate. The copper substrate has high thermal conductivity and electrical conductivity compared to the aluminum substrate. Accordingly, when the first substrate 320 is an aluminum substrate and the second substrate 380 is a copper substrate, it is possible to satisfy both high voltage resistance performance on the low temperature side and high heat dissipation performance on the high temperature side.

[0076] Then, the first substrate 320 is disposed on the first insulating layer 310, and the second insulating layer 330 is disposed on the first substrate 320. In this manner, when insulating layers are disposed on all sides of the first substrate 320, the voltage resistance performance of the first substrate 320 side can be further improved.

[0077] In this case, the first insulating layer 310 may be an aluminum oxide layer. When the first insulating layer 310 is an aluminum oxide layer, the voltage resistance performance can be improved without increasing the thermal resistance on the first substrate 320 side. In this case, the thickness of the first insulating layer 310 may be 20 to 100 μm, preferably 30 to 80 μm, and more preferably 35 to 60 μm. When the thickness of the first insulating layer 310 satisfies such a numerical range, high thermal conductivity performance and voltage resistance performance can be simultaneously satisfied.

[0078] At this time, the total thickness of the insulating layers on the first substrate 320 side, i.e., the sum of the thickness of the first insulating layer 310 and the thickness of the second insulating layer 330, may be 80 μm or more, preferably 80 to 480 μm. In general, the thicker the insulating layer, the higher the voltage resistance performance. However, the thicker the insulating layer, the higher the thermal resistance becomes. However, in the embodiment of the present invention, the insulating layers on the first substrate 320 side are arranged separately on both sides of the first substrate 320, and in particular, an aluminum oxide layer is arranged under the first substrate 320, so that it is possible to simultaneously satisfy high thermal conductivity performance and voltage resistance performance.

[0079] 3, the second insulating layer 330 and the third insulating layer 370 may be made of a resin layer including at least one of an epoxy resin composition including an epoxy resin and an inorganic filler and a silicone resin composition including PDMS (polydimethylsiloxane). Accordingly, the second insulating layer 330 can improve the insulation, bonding strength, and thermal conductivity between the first substrate 320 and the first electrode 340, and the third insulating layer 370 can improve the insulation, bonding strength, and thermal conductivity between the second electrode 360 ​​and the second substrate 380.

[0080] Here, the inorganic filler may be contained in an amount of 68 to 88 vol% of the resin layer. If the inorganic filler is contained in an amount of less than 68 vol%, the thermal conductivity effect may be low, and if the inorganic filler is contained in an amount of more than 88 vol%, the resin layer may easily break.

[0081] The epoxy resin may include an epoxy compound and a curing agent. At this time, the epoxy compound may be included in a volume ratio of 10 to 10 of the curing agent. Here, the epoxy compound may include at least one of a crystalline epoxy compound, a non-crystalline epoxy compound, and a silicon epoxy compound. The inorganic filler may include aluminum oxide and a nitride, and the nitride may be included in an amount of 55 to 95 wt% of the inorganic filler, more preferably 60 to 80 wt%. When the nitride is included in such a numerical range, the thermal conductivity and the bonding strength can be increased. Here, the nitride may include at least one of boron nitride and aluminum nitride.

[0082] In this case, the particle size D50 of the boron nitride aggregates may be 250 to 350 μm, and the particle size D50 of the aluminum oxide may be 10 to 30 μm. When the particle size D50 of the boron nitride aggregates and the particle size D50 of the aluminum oxide satisfy these numerical ranges, the boron nitride aggregates and the aluminum oxide may be uniformly dispersed in the resin layer, and therefore the resin layer as a whole may have uniform heat conduction effect and adhesive performance.

[0083] At this time, it is advantageous in terms of thermal conductivity that the second insulating layer 330 made of a resin layer is arranged as thin as possible within the limits of maintaining the insulating performance and adhesive performance between the first substrate 320 and the first electrode 340. According to the embodiment of the present invention, since the first insulating layer 310 made of an aluminum oxide layer is arranged together with the second insulating layer 330 with the first substrate 320 sandwiched therebetween, the low temperature part side can have sufficient voltage resistance performance even if the thickness of the second insulating layer 330 made of a resin layer is the same as the thickness of the third insulating layer 370 made of the same material or is smaller than the thickness of the third insulating layer 370. Accordingly, the thickness of the second insulating layer 330 made of a resin layer may be the same as the thickness of the third insulating layer 370 or may be smaller than the thickness of the third insulating layer 370.

[0084] In particular, the third insulating layer 370 may be formed to be thicker than the second insulating layer 330. As described above, the temperature of the high temperature portion may rise to about 180° C. or more when the thermoelectric element 300 is operated. If the third insulating layer 370 is made of a soft resin layer according to an embodiment of the present invention, the third insulating layer 370 may serve to reduce thermal shock between the second electrode 360 ​​and the second substrate 380.

[0085] Meanwhile, referring to FIG. 6, the second insulating layer 330 may include a second aluminum oxide layer, and the third insulating layer 370 may be formed of a resin layer including at least one of an epoxy resin composition including an epoxy resin and an inorganic filler, and a silicone resin composition including PDMS (polydimethylsiloxane). As described above, the withstand voltage performance is more important on the low temperature side, and the bonding performance is more important on the high temperature side. Accordingly, when the second insulating layer 330 is formed of a second aluminum oxide layer, it can have a higher withstand voltage performance than when it is formed of a resin layer. Also, when the third insulating layer 370 is formed of a resin layer, the bonding performance between the second electrode 360 ​​and the second substrate 380 can be ensured.

[0086] 7, the second insulating layer 330 includes the second aluminum oxide layer 334 disposed on the first substrate 320, and may further include a resin layer 332 disposed on the second aluminum oxide layer 334. In this case, the resin layer 332 included in the second insulating layer 330 may increase the adhesive strength between the second aluminum oxide layer 334 and the first electrode 340. That is, the resin layer 332 included in the second insulating layer 330 may be formed only to the extent that it provides adhesive strength between the second aluminum oxide layer 334 and the first electrode 340, and therefore the thickness of the resin layer 332 included in the second insulating layer 330 may be smaller than the thickness of the second aluminum oxide layer 334 and the thickness of the third insulating layer 370.

[0087] As described above, according to the embodiment of the present invention, a thermoelectric element is obtained in which the structure of the substrate and the insulating layer is modified to match the difference in characteristics between the low temperature portion and the high temperature portion of the thermoelectric element.

[0088] At this time, at least one of the first aluminum oxide layer 312 and the second aluminum oxide layer 334 may be formed by anodizing the aluminum substrate of the first substrate 320. Alternatively, at least one of the first aluminum oxide layer 312 and the second aluminum oxide layer 334 may be formed by a dipping process or a spray process.

[0089] Meanwhile, as shown in Figures 8 and 9, at least one of the first aluminum oxide layer 312 and the second aluminum oxide layer 334 may be connected to each other at a side of the aluminum substrate by forming an extension 340 extending along the aluminum substrate of the first substrate 320. As a result, an aluminum oxide layer may be formed on the entire surface of the aluminum substrate, which can further improve the voltage resistance performance of the low temperature portion.

[0090] Meanwhile, as described above, a heat sink may be further disposed on the high temperature side. The second substrate 380 and the heat sink 390 on the high temperature side may be integrally formed, or the second substrate 380 and the heat sink 390 may be bonded to each other separately. In this case, if a metal oxide layer is formed on the second substrate 380, it may be difficult to bond the second substrate 380 and the heat sink 390. Accordingly, in order to increase the bonding strength between the second substrate 380 and the heat sink 390, a metal oxide layer may not be formed between the second substrate 380 and the heat sink 390. That is, if the second substrate 380 is a copper substrate, a copper oxide layer may not be formed on the surface of the copper substrate. To this end, the copper substrate may be surface-treated in advance to prevent oxidation of the copper substrate. For example, when the copper substrate is plated with a metal layer such as nickel, which is less easily oxidized than copper, it is possible to prevent the formation of a metal oxide layer on the copper substrate.

[0091] In this way, according to the embodiment of the present invention, a thermoelectric element can be obtained in which the substrate and insulating layer structure on the low temperature side is different from the substrate and insulating layer structure on the high temperature side, reflecting the difference in characteristics between the low temperature and high temperature parts of the thermoelectric element.

[0092] Table 1 and Figure 10 show the results of a simulation of the effect of insulating layer thickness on the withstand voltage. An insulating layer was formed on an aluminum substrate by anodizing, and the withstand voltage was measured according to the thickness of the insulating layer.

[0093] [Table 1]

[0094] 10, it can be seen that the thicker the insulating layer is, the higher the withstand voltage performance is. In particular, when the insulating layer is 80 μm or thicker, it can be seen that a withstand voltage performance of 3.6 kV or more is obtained.

[0095] Table 2 shows the results of measuring the thermal resistance of the thermoelectric elements according to the comparative example and the embodiment.

[0096] In the comparative example, an insulating layer made of a resin layer was placed on a copper substrate, in Example 1, an aluminum substrate was placed on an aluminum oxide layer, and then an insulating layer made of a resin layer was further placed on it, in Example 2, an aluminum oxide layer was formed on both sides of the aluminum substrate, and in Example 3, an aluminum oxide layer was formed on both sides of the aluminum substrate, and then an insulating layer made of a resin layer was further placed on it.

[0097] [Table 2]

[0098] Referring to Table 2, it can be seen that the comparative example has a higher thermal resistance than Examples 1 to 3, even though the total thickness of the insulating layer is 40 μm, which is smaller than the total thickness of the insulating layer in Examples 1 to 3. It can also be seen that, compared to Example 1 in which an aluminum oxide layer is disposed on only one side of the aluminum substrate, Examples 2 and 3 in which aluminum oxide layers are disposed on both sides of the aluminum substrate have significantly lower thermal resistance. In addition, in the case of Example 3 in which a resin layer is further disposed on the aluminum oxide layer, the thermal resistance is similar to that of Example 2, but the bonding performance between the aluminum substrate and the electrodes may be even higher.

[0099] On the other hand, FIG. 11 shows the results of a simulation of the change in thermal resistance depending on the thickness of the insulating layer in the structures according to the comparative example, the second embodiment, and the third embodiment.

[0100] 11, it can be seen that the thermal resistance increases rapidly as the thickness of the resin layer is increased in the structures according to the comparative example and Example 3. In contrast, it can be seen that the thermal resistance level when the resin layer is 40 μm thick is obtained even when the thickness of the aluminum oxide layer is increased to 480 μm in the structure according to Example 2.

[0101] The thermoelectric element according to the embodiment of the present invention may be used in power generation devices, cooling devices, heating devices, etc. In particular, the thermoelectric element according to the embodiment of the present invention may be mainly applied to optical communication modules, sensors, medical devices, measuring devices, the aerospace industry, refrigerators, chillers, automobile ventilation seats, cup holders, washing machines, dryers, wine cellars, water purifiers, power supply devices for sensors, thermopiles, etc.

[0102] Here, an example of a medical device to which the thermoelectric element according to the embodiment of the present invention is applied is a PCR (Polymerase Chain Reaction) device. The PCR device is a device for amplifying DNA to determine the base sequence of the DNA, and requires precise temperature control and thermal cycling. For this purpose, a Peltier-based thermoelectric element can be applied.

[0103] Another example of a medical device to which the thermoelectric element according to the embodiment of the present invention may be applied is a photodetector. Here, photodetectors include infrared / ultraviolet detectors, CCD (Charge Coupled Device) sensors, X-ray detectors, TTRS (Thermoelectric Thermal Reference Sources), etc. A Peltier-based thermoelectric element may be applied to cool the photodetector. As a result, it is possible to prevent changes in wavelength, reductions in output, and reductions in resolution caused by an increase in temperature inside the photodetector.

[0104] Further examples of applications of the thermoelectric device according to the embodiment of the present invention to medical devices include the immunoassay field, in vitro diagnostics field, general temperature control and cooling systems, physical therapy field, liquid chiller systems, blood / plasma temperature control field, etc. Accordingly, precise temperature control is possible.

[0105] Another example of a medical device to which the thermoelectric element according to the embodiment of the present invention is applied is an artificial heart, which can be used to supply power to the artificial heart.

[0106] Examples of applications of the thermoelectric element according to the embodiment of the present invention in the aerospace industry include star tracking systems, thermal imaging cameras, infrared / ultraviolet detectors, CCD sensors, Hubble Space Telescope, TTRS, etc. Accordingly, the temperature of the image sensor can be maintained.

[0107] Other examples of applications of thermoelectric devices according to embodiments of the present invention in the aerospace industry include cooling devices, heaters, and power generation devices.

[0108] In addition, the thermoelectric device according to the embodiment of the present invention may be applied to other industrial fields for power generation, cooling, and heating.

[0109] Although the present invention has been described above with reference to preferred embodiments, it will be understood that those skilled in the art can make various modifications and variations of the present invention without departing from the spirit and scope of the present invention as set forth in the following claims.

Claims

1. A first insulating layer; a first substrate disposed on the first insulating layer; a second insulating layer disposed on the first substrate; a first electrode disposed on the second insulating layer; a P-type thermoelectric leg and an N-type thermoelectric leg disposed on the first electrode; a second electrode disposed on the P-type thermoelectric leg and the N-type thermoelectric leg; a third insulating layer disposed on the second electrode; a second substrate disposed on the third insulating layer; and a heat sink disposed on the second substrate; the first insulating layer is a first aluminum oxide layer; the first substrate is an aluminum substrate; the second substrate is a copper substrate; The first substrate is a low temperature portion and the second substrate is a high temperature portion, A thermoelectric element, the surface of the copper substrate disposed between the copper substrate and the heat sink being plated with nickel.

2. The thermoelectric element according to claim 1 , wherein the second insulating layer and the third insulating layer are each made of a resin layer containing at least one of an epoxy resin composition and a silicone resin composition.

3. The thermoelectric element of claim 2 , wherein the second insulating layer has a thickness equal to or smaller than a thickness of the third insulating layer.

4. The thermoelectric element according to claim 1 , wherein the second insulating layer includes a second aluminum oxide layer, and the third insulating layer is a resin layer including at least one of an epoxy resin composition and a silicone resin composition.

5. The thermoelectric element according to claim 4 , wherein the second insulating layer is disposed on the second aluminum oxide layer and further comprises a resin layer including at least one of an epoxy resin composition and a silicone resin composition.

6. The thermoelectric element according to claim 5 , wherein the resin layer included in the second insulating layer has a thickness smaller than the thickness of the second aluminum oxide layer and the thickness of the third insulating layer.

7. The thermoelectric element of claim 5 , wherein at least one of the first aluminum oxide layer and the second aluminum oxide layer is formed by anodizing an aluminum substrate.

8. The thermoelectric element of claim 5 , wherein at least one of the first aluminum oxide layer and the second aluminum oxide layer extends along and is connected to a side surface of the aluminum substrate.

9. The thermoelectric element of claim 1 , wherein no copper oxide layer is disposed between the copper substrate and the heat sink.

10. The thermoelectric element of claim 1 , wherein a power source is coupled to the first electrode.

11. 11. The thermoelectric element of claim 10, wherein the positive and negative terminals of the power source are coupled to the first electrode and extend down through the second insulating layer, the first substrate and the first insulating layer.

12. The thermoelectric element of claim 10 , wherein the positive and negative terminals of the power source are connected to the first electrode and are brought out laterally onto the first insulating layer, the first substrate, and the second insulating layer.

13. The thermoelectric element according to claim 1 , wherein the first insulating layer has a thickness of 20 μm to 100 μm.

14. 2. The thermoelectric element according to claim 1, wherein the sum of the thicknesses of the first insulating layer and the second insulating layer is 80 μm to 480 μm.

15. 3. The thermoelectric element according to claim 2, wherein the resin layer forming the second insulating layer and the resin layer forming the third insulating layer are made of the same material, and the thickness of the third insulating layer is greater than the thickness of the second insulating layer.

16. A first insulating layer; a first substrate disposed on the first insulating layer; a second insulating layer disposed on the first substrate; a first electrode disposed on the second insulating layer; a P-type thermoelectric leg and an N-type thermoelectric leg disposed on the first electrode; a second electrode disposed on the P-type thermoelectric leg and the N-type thermoelectric leg; a third insulating layer disposed on the second electrode; a second substrate disposed on the third insulating layer; and a heat sink disposed on the second substrate; the first insulating layer is a first aluminum oxide layer; the first substrate is an aluminum substrate; the second substrate is a copper substrate; The first substrate is a low temperature portion and the second substrate is a high temperature portion, A power generating device including a thermoelectric element, wherein the surface of the copper substrate disposed between the copper substrate and the heat sink is plated with nickel.

17. A first insulating layer; a first substrate disposed on the first insulating layer; a second insulating layer disposed on the first substrate; a first electrode disposed on the second insulating layer; a P-type thermoelectric leg and an N-type thermoelectric leg disposed on the first electrode; a second electrode disposed on the P-type thermoelectric leg and the N-type thermoelectric leg; a third insulating layer disposed on the second electrode; a second substrate disposed on the third insulating layer; and a heat sink disposed on the second substrate; the first insulating layer is a first aluminum oxide layer; the first substrate is an aluminum substrate; the second substrate is a copper substrate; The first substrate is a low temperature portion and the second substrate is a high temperature portion, A cooling and heating device including a thermoelectric element, wherein the surface of the copper substrate disposed between the copper substrate and the heat sink is plated with nickel.

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