HEAT EXCHANGE DEVICE
A heat exchange device includes a heat exchanger disposed in connection with at least one of a heat-dissipation electrode and a heat-absorption electrode, between which a plurality of thermoelectric elements is connected in series, via an insulating resin layer, which is composed of an epoxy resin or polyimide resin doped with fillers having high thermal conductivity, without intervention of a substrate. The heat exchanger corresponds to a plurality of corrugated fins which are constituted of a plurality of joint regions joining with one of the heat-dissipation electrode and heat-absorption electrode and a plurality of non-joint regions projecting externally from a plurality of gaps formed between the joint regions adjacently aligned together, wherein the joint regions and non-joint regions are alternately aligned. Thus, it is possible to achieve high reliability by reducing thermal resistance and thermal stress while increasing the maximum heat absorption coefficient (Qmax).
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1. Field of the Invention
The present invention relates to heat exchange devices including heat exchangers coupled with thermoelectric modules having thermoelectric elements connected in series between heat-dissipation electrodes and heat-absorption electrodes.
The present application claims priority on Japanese Patent Application No. 2008-71723, the content of which is incorporated herein by reference.
2. Description of the Related Art
Conventionally-known thermoelectric modules are designed such that different types of thermoelectric elements composed of P-type and N-type semiconductors are alternately aligned and connected in series between heat-dissipation electrodes and heat-absorption electrodes via bonding metals such as solders. Various techniques have been developed to improve heat dissipation efficiency in thermoelectric modules, wherein heat exchangers are coupled to heat-dissipation substrates or heat-absorption substrates so as to form heat exchange devices, for example.
Various heat exchange devices have been developed and disclosed in various documents such as Patent Document 1.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-93106
Patent Document 1 teaches a heat exchange device 50 as shown in
The corrugated fins 53 are aligned in connection with a plurality of joint regions 53a formed on the exterior surface of the substrate 56, wherein they include heat exchange regions 53b which are projected from the thermoelectric module 50a and each of which is disposed to connect between two adjacent joint regions 53a, and wherein the width of each joint region 53a is larger than the gap between two adjacent joint regions 53a. Thus, it is possible to achieve high reliability and high heat exchange performance with a heat exchange device having a simple structure.
It is essential for the thermoelectric module 50a of the heat exchange device 50 to have a pair of substrates 51 and 56 which cause thermal resistance. Hence, the heat exchange device 50 disclosed in Patent Document 1 suffers from degradation of the maximum heat absorption coefficient (Qmax) which is a significant factor determining the performance of a thermoelectric module.
Since the thermoelectric module 50a is designed such that the thermoelectric elements 58 are aligned in connection with the substrates 51 and 56 via the electrodes 52 and 57, the thermoelectric elements 58 must be restricted in positioning between the substrates 51 and 56. This makes it difficult to sufficiently release thermal stress from the thermoelectric elements 58, thus degrading the reliability of the thermoelectric module 50a against thermal stress.
SUMMARY OF THE INVENTIONIt is an object of the present invention to provide a heat exchange device which is improved in heat absorption by reducing thermal resistance and which achieves high reliability by reducing thermal stress.
A heat exchange device of the present invention includes a heat exchanger and a thermoelectric module constituted of a plurality of thermoelectric elements which are connected in series and aligned in connection with at least one of a heat-dissipation electrode and a heat-absorption electrode, which is coupled with the heat exchanger via an insulating resin layer having high thermal conductivity and an adhesive property. The heat exchanger corresponds to a plurality of corrugated fins which are constituted of a plurality of joint regions joining with one of the heat-dissipation electrode and heat-absorption electrode via the insulating resin layer and a plurality of non-joint regions projecting externally from a plurality of gaps formed between the joint regions adjacently aligned together, wherein the joint regions and non-joint regions are alternately aligned in connection with one of the heat-dissipation electrode and heat-absorption electrode.
Since one of the heat-dissipation electrode and heat-absorption electrode is not equipped with a substrate and is thus reduced in thermal resistance, it is possible to increase the maximum heat absorption coefficient (Qmax). The thermoelectric elements are bonded via the insulating resin layer so as to support one of the heat-dissipation electrode and heat-absorption electrode, thus eliminating the necessity of a substrate.
Thermal stress occurring in the corrugated fins is absorbed by the non-joint regions aligned in the gaps between adjacent joint regions, thus improving reliability against thermal stress. By completely eliminating the necessity of a substrate with respect to both of the heat-dissipation electrode and heat-absorption electrode, it is possible to further reduce thermal resistance, thus further increasing the maximum heat absorption coefficient (Qmax).
Since the width of the joint region is larger than the width of the gap formed between adjacent joint regions, it is possible to efficiently transmit heat generated by the thermoelectric elements to the corrugated fins, thus improving heat exchange efficiency. It is preferable that the insulating resin layer be composed of a polyimide resin or epoxy resin which is doped with fillers having high thermal conductivity such as alumina powder, aluminum nitride powder, and magnesium oxide powder.
These and other objects, aspects, and embodiments of the present invention will be described in more detail with reference to the following drawings.
The present invention will be described in further detail by way of examples with reference to the accompanying drawings.
1. FIRST EMBODIMENTA pair of terminals 15a is formed on one end of the heat-absorption electrode 15 in order to establish electric connections with leads 17. A thermoelectric module 10a is constituted of the heat-dissipation electrode 12, the heat-absorption electrode 15, and the thermoelectric elements which are connected together in series between the electrodes 12 and 15 via the metal 16a.
The substrate 11 has high thermal conductivity (which preferably ranges from 1 W/mK to 8 W/mK), an adhesive property, and an electric insulating property, wherein it is composed of a polyimide resin or epoxy resin with a thickness ranging from 10 μm to 100 μm. Fillers such as powder particles composed of alumina (Al2O3), aluminum nitride (AlN), or magnesium oxide (MgO) and having an average particle diameter of 15 μm or less are dispersed and doped in the polyimide resin or epoxy resin so as to improve its thermal conductivity.
The heat-dissipation electrode 12 is made of a copper film or copper alloy film whose thickness ranges from 70 μm to 200 μm. The corrugated fins 13 are composed of copper, a copper alloy, aluminum, or an aluminum alloy. Each of the corrugated fins 13 is constituted of a joint region 131 joining the insulating resin layer 14 and a non-joint region 13b which project downwardly from a gap between adjacent joint regions 13a (i.e. in a direction opposite to the heat-absorption electrode 15). The width (denoted by “x”) of the joint region 13a is larger than the base width (denoted by “y”) of the non-joint region 13b.
The insulating resin layer 14 is composed of a prescribed material having high thermal conductivity (which preferably ranges from 1 W/mK to 8 W/mK), an adhesive property, and an electric insulating property such as a polyimide resin or epoxy resin with a thickness ranging from 10 μm to 100 μm. Fillers such as powder particles composed of alumina (Al2O3), aluminum nitride (AlN), or magnesium oxide (MgO) and having an average particle diameter of 15 μm or less are dispersed and doped in the polyimide resin or epoxy resin so as to improve its thermal conductivity.
Similar to the heat-dissipation electrode 12, the heat-absorption electrode 15 is composed of a copper film or copper alloy film with a thickness ranging from 70 μm to 200 μm. A plurality of thermoelectric elements 16 is disposed and connected in series between the electrodes 12 and 15. The thermoelectric elements 16 are composed of compounds of N-type and P-type semiconductors. The thermoelectric elements 16 are electrically connected in series in the order of P, N, P, N, . . . in such a way that they are soldered to the electrodes 12 and 15 by use of soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, thus forming solder layers 16a. In this connection, nickel plating is adapted to soldered ends of each thermoelectric element 16.
It is preferable that the thermoelectric element 16 be formed as sintered body composed of Bi—Te (bismuth-tellurium) thermoelectric materials which demonstrate high performance at room temperature. It is preferable that P-type semiconductor compounds be composed of ternary elements such as Bi—Sb—Te, and N-type semiconductor compounds be composed of quadruple elements such as Bi—Sb—Te—Se. Specifically, the composition of P-type semiconductor compounds is expressed as Bi0.5Sb1.5Te3 while the composition of N-type semiconductor compounds is expressed as Bi1.9Sb0.1Te2.6Se0.4, wherein both of them are formed by way of hot-press sintering.
Since the heat exchange device 10 of the first embodiment is designed such that the substrate 11 is disposed in connection with only the heat-dissipation electrode 12, it is possible to reduce thermal resistance, thus improving the maximum heat absorption coefficient (Qmax). None of the insulating resin layer 14 and the heat-absorption electrode 15 is disposed in gaps between adjacent joint regions 13a among the corrugated fins 13, wherein these gaps absorb thermal stress. Thus, it is possible to avoid the occurrence of cracks and defects due to thermal stress in advance, and it is possible to achieve high reliability in the heat exchange device 10.
Next, an actual manufacturing method of the heat exchange device 10 will be described below.
The substrate 11 composed of an insulating resin such as a polyimide resin or epoxy resin is fabricated with a thickness ranging from 10 μm to 100 μm in such a way that the heat-dissipation electrode 12 is formed on the lower surface thereof. In addition, the corrugated fins 13 composed of copper, a copper alloy, aluminum, or an aluminum alloy are fabricated in such a way that the heat-absorption electrode 15 is attached to each of the joint regions 13a via the insulating resin layer whose thickness ranges from 10 μm to 100 μm. Furthermore, the thermoelectric elements 16 are fabricated using P-type and N-type semiconductor compounds.
The heat-dissipation electrode 12 and the heat-absorption electrode 15 each composed of a copper film or copper alloy film are each formed with a prescribed thickness (ranging from 70 μm to 200 μm) and a prescribed electrode pattern by way of DBC (Direct Bonding Copper), for example. Nickel plating is adapted to distal ends (opposite ends in the longitudinal direction) of P-type and N-type semiconductor compounds.
The thermoelectric elements composed of P-type and N-type semiconductor compounds are alternately aligned on the heat-absorption electrodes 15 (composed of a copper film or copper alloy film) attached to the corrugated fins 13, wherein the substrate 11 (composed of an insulating resin) having the heat-dissipation electrode 12 (composed of a copper film or copper alloy film) is disposed on the thermoelectric elements 16. The upper ends of the thermoelectric elements 16 (composed of P-type and N-type semiconductor compounds which are alternately aligned below the heat-dissipation electrode 12) are soldered to the lower surface of the heat-dissipation electrode 12 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, while the lower ends of the thermoelectric elements 16 are soldered to the upper surface of the heat-absorption electrode 15 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy.
Thus, the thermoelectric elements 16 are connected in series between the heat-dissipation electrode 12 and the heat-absorption electrode 15 via the solder layers 16a such that the P-type and N-type semiconductor compounds thereof are alternately aligned. Thereafter, the leads 17 are soldered to the terminals 15a formed on one end of the heat-absorption electrode 15. This completes the production of the heat exchange device 10.
2. SECOND EMBODIMENTIn contrast to the heat exchange device 10 where the corrugated fins 13 are arranged on the heat-absorption electrode 15 only, the heat exchange device 20 is designed such that corrugated fins are arranged on both of the heat-absorption and heat-dissipation sides. The heat exchange device 20 has a thermoelectric module 20a which is similar to the thermoelectric module 10a installed in the heat exchange device 10.
Specifically, the heat exchange device 20 includes first corrugated fins 21 (which collectively serve as a heat-dissipation side heat exchanger), a joint film 22 composed of a copper film or copper alloy film for entirely covering the lower surfaces of the first corrugated fins 21, and a heat-dissipation electrode 24 which is attached to the joint film 22 via an insulating resin layer 23 having high thermal conductivity and an adhesive property which is adhered to the lower surface of the joint film 22 entirely. In addition, the heat exchange device 20 includes second corrugated fins 25 (which collectively serve as a heat-absorption side heat exchanger) and a heat-absorption electrode 27 which is attached to the upper surfaces of the second corrugated fins 25 via an insulating resin layer 26 having high thermal conductivity and an adhesive property. A plurality of thermoelectric elements 28 is electrically connected in series and connected between the electrodes 24 and 27 via solder layers (or metals) 28a, thus forming the thermoelectric module 20a. A pair of terminals 27a is formed on one end of the heat-absorption electrode 27 so as to establish an electrical connection with leads 29.
Both of the first corrugated fins 21 and the second corrugated fins 25 are composed of the foregoing materials used for the corrugated fins 13. The first corrugated fins 21 are constituted of joint regions 21a and non-joint regions 21b which project upwardly from gaps between adjacent joint regions 21a, while the second corrugated fins 25 are constituted of joint regions 25a and non-joint regions 25b which project downwardly from gaps between adjacent joint regions 25a. Herein, the width x of the joint region 21a is larger than the width y of the lower end of the non-joint region 21b, while the width x of the joint region 25a is larger than the width y of the upper end of the non-joint region 25b. The joint film 22 composed of a copper film or copper alloy film is attached to the joint regions 21 a so as to entirely cover the lower surfaces of the first corrugated fins 21. The insulating resin layers 23 and 26 are each composed of the foregoing material used for the insulating resin layer 14; specifically, they are each composed of a polyimide resin or epoxy resin with a thickness ranging from 10 μm to 100 μm.
Fillers such as powder particles composed of alumina (Al2O3), aluminum nitride (AlN), or magnesium oxide (MgO) and having an average particle diameter of 15 μm or less are dispersed and doped in the polyimide resin or epoxy resin so as to improve its thermal conductivity. Similar to the heat-dissipation electrode 12 and the heat-absorption electrode 15, the heat-dissipation electrode 24 and the heat-absorption electrode 27 are each composed of a copper film or copper alloy film with a thickness ranging from 70 μm to 200 μm. A plurality of thermoelectric elements 28 is electrically connected in series and connected between the electrodes 24 and 27. The thermoelectric elements 28 are soldered to the electrodes 24 and 27 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, thus forming the solder layers 28a. The composition of the thermoelectric elements 28 is identical to the composition of the thermoelectric elements 16.
Since the heat exchange device 20 is fabricated without using the substrate, it is possible to reduce the thermal resistance, thus improving the maximum heat absorption coefficient (Qmax). None of the insulating resin layer 26 and the heat-absorption electrode 27 is disposed in gaps between the joint regions 25a of the corrugated fins 25, wherein these gaps absorb thermal stress. Thus, it is possible to avoid the occurrence of cracks and defects in the thermoelectric elements 28 due to thermal stress in advance, and it is possible to achieve high reliability in the heat exchange device 20.
Next, an actual manufacturing method of the heat exchange device 20 will be described below.
The first corrugated fins 21 composed of copper, a copper alloy, aluminum, or an aluminum alloy are fabricated in such a way that the joint regions 21a are attached to the joint film 22 so as to connect with the heat-dissipation electrode 24 via the insulating resin layer 23 whose thickness ranges from 10 μm to 100 μm. In addition, the second corrugated fins 25 composed of copper, a copper alloy, aluminum, or an aluminum alloy are fabricated in such a way that the joint regions 25a are attached to the heat-absorption electrode 27 via the insulating resin layer 26 whose thickness ranges from 10 μm to 100 μm. Furthermore, the thermoelectric elements 28 are formed using P-type and N-type semiconductor compounds.
The heat-dissipation electrode 24 and the heat-absorption electrode 27 each composed of a copper film or copper alloy film are each formed in a prescribed electrode pattern with a thickness ranging from 70 μm to 200 μm by way of DBC (Direct Bonding Copper). Nickel plating is adapted to the distal ends (i.e. opposite ends in the longitudinal direction) of P-type and N-type semiconductor compounds.
The thermoelectric elements 28 are arranged on the heat-absorption electrode 27 (composed of a copper or copper alloy film) attached to the second corrugated fins 25 such that P-type and N-type semiconductor compounds are alternately aligned. The first corrugated fins 21 attached to the heat-dissipation electrode 24 (composed of a copper film or copper alloy film) are disposed above the thermoelectric elements 28. The upper ends of the thermoelectric elements 28 (composed of P-type and N-type semiconductor compounds below the heat-dissipation electrode 24) are soldered to the lower surface of the heat-dissipation electrode 24 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, while the lower ends of the thermoelectric elements 28 are soldered to the upper surface of the heat-absorption electrode 27 via soldering materials such as an SnSb ally, SnAu alloy, and SnAgCu alloy.
The thermoelectric elements 28 are connected in series between the heat-dissipation electrode 24 and the heat-absorption electrode 27 via the solder layers 28a such that P-type and N-type semiconductor compounds thereof are alternately aligned. Thereafter, the leads 29 are soldered to the terminals 27a on one end of the heat-absorption electrode 27, thus completing the production of the heat exchange device 20.
3. THIRD EMBODIMENTIn the heat exchange device 20, the lower surfaces of the corrugated fins 21 are entirely covered with the joint film 22, the lower surface of which is entirely covered with the insulating resin layer 23; but this is not a restriction. It is possible to dispose an insulating resin layer in connection with only the joint regions of corrugated fins without intervention of a joint film. The heat exchange device 30 is designed to dispose an insulating resin layer in connection with only the joint regions of corrugated fins without using a joint film. As shown in
Specifically, the heat exchange device 30 includes first corrugated fins 31 (which collectively serve as a heat-dissipation side heat exchanger), a heat-dissipation electrode 33 which is attached below the first corrugated fins 31 via an insulating resin layer 32 having high thermal conductivity and an adhesive property, second corrugated fins 34 (which collectively serve as a heat-absorption side heat exchanger), and a heat-absorption electrode 36 which is attached above the second corrugated fins via an insulating resin layer 35 having high thermal conductivity and an adhesive property. A plurality of thermoelectric elements 37 is electrically connected in series between the electrodes 33 and 36 via solder layers (or metals) 37a. A pair of terminals 36a is formed on one end of the heat-absorption electrode 36 so as to establish an electrical connection with leads 38.
Both the first corrugated fins 31 and the second corrugated fins 34 are composed of the foregoing material used for the corrugated fins 13. The first corrugated fins 31 are constituted of joint regions 31a and non-joint regions 31b which project upwardly from gaps between adjacent joint regions 31a, while the second corrugated fins 34 are constituted of joint regions 34a and non-joint regions 34b which project downwardly from gaps between adjacent joint regions 34a. The width x of the joint region 31a is larger than the width y of the lower end of the non-joint region 31b, while the width x of the joint region 34a is larger than the width y of the upper end of the non-joint region 34b. Both the insulating region layers 32 and 35 are composed of the foregoing material used for the insulating region layer 14; specifically, they are each composed of a polyimide resin or epoxy resin with a thickness ranging from 10 μm to 100 μm.
Fillers such as powder particles composed of alumina (Al2O3), aluminum nitride (AlN), or magnesium oxide (MgO) and having an average particle diameter of 15 μm or less are dispersed and doped in the polyimide resin or epoxy resin so as to improve its thermal conductivity. Similar to the heat-dissipation electrode 12 and the heat-absorption electrode 15, the heat-dissipation electrode 33 and the heat-absorption electrode 36 are each composed of a copper film or copper alloy film with a thickness ranging from 70 μm to 200 μm. A plurality of thermoelectric elements 37 is electrically connected in series between the electrodes 33 and 36. The distal ends of the thermoelectric elements 37 are soldered to the electrodes 33 and 36 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, thus forming solder layers 37a. The composition of the thermoelectric elements 37 is identical to the composition of the thermoelectric elements 16.
Since the heat exchange device 30 does not use a substrate, it is possible to reduce thermal resistance, thus improving the maximum heat absorption coefficient (Qmax). None of the insulating resin layers 32 and 35 and the electrodes 33 and 36 is disposed in gaps between adjacent joint regions 31a and 34a of the corrugated fins 31 and 34, wherein these gaps absorb thermal stress. Thus, it is possible to avoid the occurrence of cracks and defects in the thermoelectric elements 37 due to thermal stress, and it is possible to achieve high reliability in the heat exchange device 30.
Next, an actual manufacturing method of the heat exchange device 30 will be described below.
The first corrugated fins 31 composed of copper, a copper alloy, aluminum, or an aluminum alloy are fabricated in such a way that the heat-dissipation electrode 33 is attached to the joint regions 31a via the insulating resin layer whose thickness ranges from 10 μm to 100 μm. In addition, the second corrugated fins 34 composed of copper, a copper alloy, aluminum, or an aluminum alloy are fabricated in such a way that the heat-absorption electrode 36 is attached to the joint regions 34a via the insulating resin layer whose thickness ranges from 10 μm to 100 μm. Furthermore, the thermoelectric elements 37 are formed using P-type and N-type semiconductor compounds.
The heat-dissipation electrode 33 and the heat-absorption electrode 36 are each composed of a copper film or copper alloy film, wherein they are each formed in a prescribed electrode pattern with a prescribed thickness ranging from 70 μm to 200 μm by way of DBC (Direct Bonding Copper). Nickel plating is adapted to the distal ends (i.e. opposite ends in the longitudinal direction) of P-type and N-type semiconductor compounds.
The thermoelectric elements 37 are arranged above the heat-absorption electrode 36 (composed of a copper film or copper alloy film) attached to the second corrugated fins 34 such that P-type and N-type semiconductor compounds are alternately aligned. The first corrugated fins 31 attached to the heat-dissipation electrode 33 (composed of a copper film or copper alloy film) are arranged above the thermoelectric elements 37. The upper ends of the thermoelectric elements 37 composed of P-type and N-type semiconductor compounds below the heat-dissipation electrode 33 are soldered to the lower surfaces of the heat-dissipation electrode 33 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, while the lower ends of the thermoelectric elements 37 are soldered to the upper surface of the heat-absorption electrode 36 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy.
The thermoelectric elements 37 are connected in series between the heat-dissipation electrode 33 and the heat-absorption electrode 36 via the solder layers 37a such that P-type and N-type semiconductor compounds thereof are alternately aligned. Thereafter, the leads 38 are soldered to the terminals 36a on one end of the heat-absorption electrode 36, thus completing the production of the heat exchange device 30.
4. FOURTH EMBODIMENTIn the heat exchange devices 10, 20, and 30, a series of electrodes (e.g. four electrodes in the illustrations of
The heat exchange device 40 includes first corrugated fins 41 (which collectively serve as a heat-dissipation side heat exchanger), heat-dissipation electrodes 43 which are attached to the lower surfaces of the first corrugated fins 41 via insulating resin layers 42 having high thermal conductivity and an adhesive property, second corrugated fins 44 (which collectively serve as a heat-absorption side heat exchanger), and heat-absorption electrodes 46 which are attached to the upper surfaces of the second corrugated fins 44 via insulating resin layers 45 having high thermal conductivity and an adhesive property. A plurality of thermoelectric elements 47 are electrically connected in series and disposed between the electrodes 43 and 46 via solder layers (or metals) 47a. A pair of terminals 46a is formed on one end of the heat-absorption electrode 46 so as to establish an electrical connection with a pair of leads 48.
Both of the first corrugated fins 41 and the second corrugated fins 44 are composed of the foregoing material used for the corrugated fins 13. The first corrugated fins 41 are constituted of joint regions 41a and non-joint regions 41b which project upwardly from gaps between adjacent joint regions 41a, while the second corrugated fins 44 are constituted of joint regions 44a and non-joint regions 44b which project downwardly from gaps between adjacent joint regions 44a. Specifically, as shown in
Both the insulating resin layers 42 and 45 are composed of the foregoing material used for the insulating resin layer 14; specifically, they are each composed of a polyimide resin or epoxy resin with a thickness ranging from 10 μm to 100 μm. Fillers such as powder particles composed of alumina (Al2O3), aluminum nitride (AlN), or magnesium oxide (MgO) and having an average particle diameter of 15 μm or less are dispersed and doped in the polyimide resin or epoxy resin so as to improve its thermal conductivity. Similar to the heat-dissipation electrode 12 and the heat-absorption electrode 15, the heat-dissipation electrodes 43 and the heat-absorption electrodes 46 are each composed of a copper film or copper alloy film with a thickness ranging from 70 μm to 200 μm. A plurality of thermoelectric elements 47 is electrically connected in series and disposed between the electrodes 43 and 46.
The upper ends of the thermoelectric elements 47 are soldered to the heat-dissipation electrodes 43 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, while the lower ends of the thermoelectric elements 47 are soldered to the heat-absorption electrodes 46 via soldering materials, thus forming the solder layers 47a. The composition of the thermoelectric elements 47 is identical to the composition of the thermoelectric elements 16.
Since the heat exchange device 40 does not use a substrate, it is possible to reduce thermal resistance, thus improving the maximum heat absorption coefficient (Qmax). None of the insulating resin layers 42 and the heat-dissipation electrodes 43 is formed in gaps between adjacent joint regions 41a of the first corrugated fins 41, wherein these gaps absorb thermal stress. None of the insulating resin layers 46 and the heat-absorption electrodes 46 is formed in gaps between the joint regions 44a of the second corrugated fins 44, wherein these gaps absorb thermal stress. Thus, it is possible to avoid the occurrence of cracks and defects in the thermoelectric elements due to thermal stress, and it is possible to achieve high reliability in the heat exchange device 40.
Next, an actual manufacturing method of the heat exchange device 40 will be described below.
The first corrugated fins 41 composed of aluminum or an aluminum alloy are fabricated in such a way that the heat-dissipation electrodes 43 are attached to the joint regions 41a via the insulating resin layers 42 whose thickness ranges from 10 μm to 100 μm. In addition, the second corrugated fins 44 composed of copper, a copper alloy, aluminum, or an aluminum alloy are fabricated in such a way that the heat-absorption electrodes 46 are attached to the joint regions 44a via the insulating resin layers 45 whose thickness ranges from 10 μm to 100 μm. Furthermore, the thermoelectric elements 47 are formed using P-type and N-type semiconductor compounds.
Both of the heat-dissipation electrodes 43 and the heat-absorption electrodes 46 are each composed of a copper film or copper alloy film and are each formed in a prescribed electrode pattern with a prescribed thickness ranging from 70 μm to 200 μm by way of DBC (Direct Bonding Copper). As shown in
The P-type and N-type semiconductor compounds of the thermoelectric elements 47 are alternately aligned on the heat-absorption electrodes 46 (composed of a copper film or copper alloy film) formed on the second corrugated fins 44. The first corrugated fins 41 having the heat-dissipation electrodes 43 (composed of a copper film or copper alloy film) are disposed above the thermoelectric elements 47. The upper ends of the thermoelectric elements 47 are soldered to the heat-dissipation electrodes 43 via soldering materials such as an SnSb alloy, SnAu alloy, and SnAgCu alloy, while the lower ends of the thermoelectric elements 47 are soldered to the heat-absorption electrodes 46 via soldering materials.
Thus, the P-type and N-type semiconductor compounds of the thermoelectric elements 47 are alternately aligned and connected in series between the heat-dissipation electrodes 43 and the heat-absorption electrodes 46 via the solder layers 47a. Thereafter, the leads 48 are soldered to the terminals 46a on one end of the heat-absorption electrode 46, thus completing the production of the heat exchange device 40.
The heat exchange device 40 is designed such that plural electrodes are aligned in two lines on the joint region of the corrugated fin; but this is not a restriction. It is possible to align plural electrodes in plural lines on the joint region of the corrugated fin.
(1) Performance Evaluation (i.e. Maximum heat Absorption Coefficient Qmax)
Maximum heat absorption coefficients (Qmax) which indicate indexes of performance evaluation were measured with respect to the heat exchange devices 10, 20, 30, 40, and 40A as well as the conventionally-known heat exchange device 50 shown in
Test examples A1-A2, B1-B3, C1-C6, D1-D2, E1-E2, and X were respectively produced in accordance with the heat exchange devices 10, 20, 30, 40, 40A, and 50. The test examples A1-A2, B1-B3, C1-C6, D1-D2, E1-E2, and X were each placed in a bell jar, in which they were each held by a soaking copper plate having high thermal capacity, silicon grease was applied to the joining area between the corrugated fins and the soaking copper plate, then, measurement was performed in a vacuum atmosphere. Measurement results are shown in Table 1.
In the measurement, the composition of P-type semiconductor compounds is expressed as Bi0.4Sb1.6Te3, while the composition of N-type semiconductor compounds is expressed as Bi1.9Sb0.1Te2.7Se0.3. The above semiconductor compounds are subjected to rapid cooling so as to produce foil powder, which is then subjected to hot pressing so as to bulk into a semiconductor material, which is cut into individual pieces each having dimensions of 1.5 mm (length)×1.5 mm (width)×1.0 mm (height). One hundred pairs of pieces are used for the measurement, wherein the electrodes 12, 15, 24, 27, 33, and 36 are all formed in a prescribed thickness of 120 μm, and each electrode has dimensions of 1.8 mm×3 mm. The corrugated fins 13, 21, 25, 31, 34, 41 and 44 composed of copper are each formed in dimensions of 40 mm (length)×40 mm (width)×10 mm (height).
The test examples A1 and A2 are produced based on the heat exchange device 10 of the first embodiment, in which the substrate 11 and the insulating resin layer 14 are each composed of a polyimide resin and epoxy resin doped with fillers composed of aluminum powder and are each formed with a thickness of 10 μm; specifically, the heat exchange device A1 is produced using the polyimide resin, while the heat exchange device A2 is produced using the epoxy resin.
The text examples B1, B2, and B3 are produced based on the heat exchange device 20 of the second embodiment, in which the insulating resin layers 24 and 26 are each composed of a polyimide resin and epoxy resin doped with fillers composed of alumina powder and a mixed powder consisting of 50% alumina power and 50% aluminum nitride (AlN) powder (in volume percentage) and are each formed with a thickness of 20 μm; specifically, the heat exchange device B1 is produced using the polyimide resin doped with alumina fillers, the heat exchange device B2 is produced using the epoxy resin doped with alumina fillers, and the heat exchange device B3 is produced using the epoxy resin doped with fillers composed of alumina powder (50%) and aluminum nitride powder (50%).
Test examples C1 to C6 are produced based on the heat exchange device 30 of the third embodiment, in which the insulating resin layers 32 and 35 are each composed of an epoxy resin and polyimide resin doped with fillers composed of alumina powder, aluminum nitride (AlN) powder, and magnesium oxide (MgO) powder and are each formed with a thickness of 20 μm; specifically, the heat exchange device C1 is produced using the epoxy resin doped with alumina fillers; the heat exchange device C2 is produced using the epoxy resin doped with aluminum nitride fillers; the heat exchange device C3 is produced using the epoxy resin doped with magnesium oxide fillers; the heat exchange device C4 is produced using the polyimide resin doped with alumina fillers; the heat exchange device C5 is produced using the polyimide resin doped with aluminum nitride fillers; and the heat exchange device C6 is produced using the polyimide resin doped with magnesium oxide fillers.
The test examples D1 and D2 are produced based on the heat exchange device 40 of the fourth embodiment, in which the insulating rein layers 42 and 45 are each composed of an epoxy resin and polyimide resin doped with fillers composed of 50% alumina powder together with 50% aluminum nitride (AlN) powder or 50% magnesium oxide (MgO) powder (in volume percentage) and are each formed with a thickness of 20 μm; specifically, the heat exchange device D1 is produced using the epoxy resin doped with alumina fillers (50%) and aluminum nitride fillers (50%), and the heat exchange device D2 is produced using the polyimide resin doped with alumina fillers (50%) and magnesium oxide fillers (50%).
The text examples E1 and E2 are produced based on the heat exchange device 40A according to a variation of the fourth embodiment, in which the insulating resin layers 42 and 45 are each composed of a polyimide resin or epoxy resin doped with fillers composed of 50% alumina powder and 50% magnesium oxide (MgO) powder (in volume percentage); specifically, the heat exchange device E1 is produced using the polyimide resin doped with alumina fillers (50%) and magnesium oxide fillers (50%), and the heat exchange device E2 is produced using the epoxy resin doped with alumina fillers (50%) and magnesium oxide fillers (50%).
The test example X is produced based on the conventionally-known heat exchange device 50 shown in
Table 1 clearly shows that all the heat exchange devices A1-A2, B1-B3, C1-C6, D1-D2, and E1-E2 based on the heat exchange devices 10, 20, 30, 40, and 40A are improved in the maximum heat absorption coefficient (Qmax) in comparison with the heat exchange device X corresponding to the conventionally-known heat exchange device 50. This is because the heat exchange devices according to the present invention are designed without using a substrate or only using a substrate on one side, thus reducing thermal resistance.
(2) Reliability Evaluation (i.e. Variations of Alternating-Current Resistance ACR)
By use of the heat exchange devices A1-A2, B1-B3, C1-C6, D1-D2, E1-E2, and X, variations (i.e. increase ratios) of alternating-current resistance (ACR) which indicates a significant index of reliability evaluation were measured in the following condition. The heat exchange devices A1-A2, B1-B3, C1-C6, D1-D2, E1-E2, and X were initially placed in a prescribed environmental condition of 95% humidity and 30° C. temperature and were then heated for two minutes such that the temperature difference between the upper portion and lower portion thereof increased from 10° C. to 90° C. and was then sustained for one minute; thereafter, they were cooled for three minutes such that the temperature difference decreased from 90° C. to 10° C. Such a temperature increase/decrease cycle (or a thermal cycle) was repeated for 10,000 times to 100,000 times.
At 10,000 cycles, 20,000 cycles, 40,000 cycles, 60,000 cycles, 80,000 cycles, and 100,000 cycles, alternating-current resistances (ACR) were measured with respect to the heat exchange devices A1-A2, B1-B3, C1-C6, D1-D2, E1-E2, and X, thus estimating ACR variations compared to ACR before the temperature increase/decrease cycle. In addition, at 10,000 cycles, 20,000 cycles, 40,000 cycles, 60,000 cycles, 80,000 cycles, and 100,000 cycles, maximum heat absorption coefficients (Qmax) were measured with respect to the heat exchange devices A1-A2, B1-B3, C1-C6, D1-D2, E1-E2, and X, thus estimating variations compared to Qmax before the temperature increase/decrease cycle. The results regarding variations of ACR and Qmax are shown in Table 2.
Table 2 clearly shows that, when the number of thermal cycles exceeds 60,000 cycles, both the ACR variations (%) and Qmax variations (%) are controlled with respect to the heat exchange devices A1-A2, B1-B3, C1-C6, D1-D2, and E1-E2 based on the heat exchange devices 10, 20, 30, 40, and 40A compared to the heat exchange device X corresponding to the conventionally-known heat exchange device 50. This is because the heat exchange devices of the present invention are designed without using a substrate or only using a substrate on one side while gaps are formed between the electrodes 15, the electrodes 27, the electrodes 33, the electrodes 36, the electrodes 43, and the electrodes 46, thus absorbing thermal stress.
6. INDUSTRIAL APPLICABILITYAll the embodiments of the present invention are designed to use polyimide resins and epoxy resins as composite resin materials; but this is not a restriction. It is possible to use other resins such as aramid resins and bismaleimide triazine (BT) resins other than polyimide resins and epoxy resins, thus achieving the aforementioned properties.
All the embodiments of the present invention are designed to use alumina powder, aluminum nitride powder, and magnesium oxide powder as filler materials; but this is not a restriction. It is possible to use other materials of high heat conductivity such as carbon powder, silicon carbide, and silicon nitride. One kind of filler material is satisfactory, but it is possible to mix two or more kinds of filler materials. In addition, fillers can be formed in arbitrary shapes such as spherical shapes and needle shapes as well as mixtures of such shapes.
Last, the present invention is not necessarily limited to the above embodiments and variations, which can be further modified within the scope of the invention as defined in the appended claims.
Claims
1. A heat exchange device including a heat exchanger and a thermoelectric module constituted of a plurality of thermoelectric elements which are connected in series and aligned in connection with at least one of a heat-dissipation electrode and a heat-absorption electrode, which is coupled with the heat exchanger via an insulating resin layer having high thermal conductivity and an adhesive property, wherein the heat exchanger corresponds to a plurality of corrugated fins which are constituted of a plurality of joint regions joining one of the heat-dissipation electrode and the heat-absorption electrode via the insulating resin layer and a plurality of non-joint regions projecting externally from a plurality of gaps formed between the joint regions adjacently aligned together, and wherein the plurality of joint regions and the plurality of non-joint regions are alternately aligned in connection with one of the heat-dissipation electrode and the heat-absorption electrode.
2. The heat exchange device according to claim 1, wherein a width of the joint region is larger than a width of the gap formed between the joint regions adjacently aligned in the corrugated fins.
3. The heat exchange device according to claim 1, wherein the insulating resin layer is composed of a polyimide resin or an epoxy resin.
4. The heat exchange device according to claim 1, wherein the insulating resin layer is doped with a plurality of fillers having high thermal conductivity.
5. The heat exchange device according to claim 4, wherein the fillers are composed of any one of an alumina powder, an aluminum nitride powder, and a magnesium oxide powder.
6. A heat exchange device comprising:
- a plurality of heat-dissipation electrodes which are separated from each other and are linearly aligned;
- a plurality of heat-absorption electrodes which are separated from each other and are linearly aligned;
- a plurality of thermoelectric elements which are connected in series and aligned between the plurality of heat-dissipation electrodes and the heat-absorption electrodes; and
- at least one heat exchanger which is disposed in connection with at least one of the heat-dissipation electrodes and the heat-absorption electrodes and which is constituted of a plurality of joint regions joining with one of the heat-dissipation electrodes and the heat-absorption electrodes via a plurality of insulating resin layers and a plurality of non-joint regions projecting externally from a plurality of gaps formed between the joint regions adjacently aligned together.
7. The heat exchange device according to claim 6, wherein the plurality of insulating resin layers is composed of a polyimide resin or an epoxy resin, which is doped with a plurality of fillers having high thermal conductivity.
Type: Application
Filed: Mar 13, 2009
Publication Date: Sep 24, 2009
Applicant: YAMAHA CORPORATION (Hamamatsu-Shi)
Inventor: YUMA HORIO (Hamamatsu-shi)
Application Number: 12/403,674
