Patent Publication Number: US-2009236087-A1

Title: Heat exchange device

Description:
BACKGROUND OF THE INVENTION 
     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  FIG. 7  in which a plurality of thermoelectric elements  58  is aligned between a pair of substrates  51  and  56  which are positioned opposite to each other. Adjacent thermoelectric elements  58  are electrically connected together via electrodes  52  and  57  which are attached to the interior surfaces of the substrates  51  and  56 , thus forming a thermoelectric module  50   a . A plurality of corrugated fins  53  is attached to one of the exterior surfaces of the substrates  51  and  56  (e.g. the exterior surface of the substrate  56  in  FIG. 7 ) via an alloy layer  55  and a bonding material  54 , thus forming a heat exchange device  50 . 
     The corrugated fins  53  are aligned in connection with a plurality of joint regions  53   a  formed on the exterior surface of the substrate  56 , wherein they include heat exchange regions  53   b  which are projected from the thermoelectric module  50   a  and each of which is disposed to connect between two adjacent joint regions  53   a , and wherein the width of each joint region  53   a  is larger than the gap between two adjacent joint regions  53   a . 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  50   a  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  50   a  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  50   a  against thermal stress. 
     SUMMARY OF THE INVENTION 
     It 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, aspects, and embodiments of the present invention will be described in more detail with reference to the following drawings. 
         FIG. 1  is a cross-sectional view showing the constitution of a heat exchange device according to a first embodiment of the present invention. 
         FIG. 2  is a cross-sectional view showing the constitution of a heat exchange device according to a second embodiment of the present invention. 
         FIG. 3  is a cross-sectional view showing the constitution of a heat exchange device according to a third embodiment of the present invention. 
         FIG. 4  is a cross-sectional view showing the constitution of a heat exchange device according to a fourth embodiment of the present invention. 
         FIG. 5A  is a plan view showing an alignment of electrodes in two lines along a joint region of each corrugated fin in the heat exchange device of  FIG. 4 . 
         FIG. 5B  is a cross-sectional view of each corrugated fin whose joint region is increased in width in conjunction with  FIG. 5A . 
         FIG. 6A  is a plan view showing an alignment of electrodes in four lines along the joint region of each corrugated fin in a heat exchange device according to a variation of the fourth embodiment. 
         FIG. 6B  is a cross-sectional view of each corrugated fin whose joint region is further increased in width in conjunction with  FIG. 6A . 
         FIG. 7  is a cross-sectional view showing the constitution of a conventionally-known heat exchange device. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in further detail by way of examples with reference to the accompanying drawings. 
     1. FIRST EMBODIMENT 
       FIG. 1  is a cross-sectional view showing the constitution of a heat exchange device  10  according to a first embodiment of the present invention. The heat exchange device  10  is constituted of a substrate  11 , a heat-dissipation electrode  12  which is formed below the substrate  11 , a plurality of corrugated fins  13  (collectively serving as a heat exchanger on a heat-absorption side, a heat-absorption electrode  15  which is bonded onto the upper surfaces of the corrugated fins  13  via an insulating resin layer  14  having a high heat conductivity and an adhesive property, and a plurality of thermoelectric elements  16  which are electrically connected in series between the electrodes  12  and  15  via a soldering layer (or a metal)  16   a.    
     A pair of terminals  15   a  is formed on one end of the heat-absorption electrode  15  in order to establish electric connections with leads  17 . A thermoelectric module  10   a  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  16   a.    
     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 (Al 2 O 3 ), 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  13   b  which project downwardly from a gap between adjacent joint regions  13   a  (i.e. in a direction opposite to the heat-absorption electrode  15 ). The width (denoted by “x”) of the joint region  13   a  is larger than the base width (denoted by “y”) of the non-joint region  13 b. 
     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 (Al 2 O 3 ), 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  16   a . 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 Bi 0.5 Sb 1.5Te   3  while the composition of N-type semiconductor compounds is expressed as Bi 1.9 Sb 0.1 Te 2.6 Se 0.4 , 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  13   a  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  13   a  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  16 a such that the P-type and N-type semiconductor compounds thereof are alternately aligned. Thereafter, the leads  17  are soldered to the terminals  15   a  formed on one end of the heat-absorption electrode  15 . This completes the production of the heat exchange device  10 . 
     2. SECOND EMBODIMENT 
       FIG. 2  is a cross-sectional view showing the constitution of a heat exchange device  20  according to a second embodiment of the present invention. 
     In 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  20   a  which is similar to the thermoelectric module  10   a  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)  28   a , thus forming the thermoelectric module  20   a . A pair of terminals  27   a  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  21   a  and non-joint regions  21   b  which project upwardly from gaps between adjacent joint regions  21   a , while the second corrugated fins  25  are constituted of joint regions  25   a  and non-joint regions  25   b  which project downwardly from gaps between adjacent joint regions  25   a . Herein, the width x of the joint region  21   a  is larger than the width y of the lower end of the non-joint region  21   b , while the width x of the joint region  25   a  is larger than the width y of the upper end of the non-joint region  25   b . 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 (Al 2 O 3 ), 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  28   a . 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  25   a  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  21   a  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  25   a  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  28   a  such that P-type and N-type semiconductor compounds thereof are alternately aligned. Thereafter, the leads  29  are soldered to the terminals  27   a  on one end of the heat-absorption electrode  27 , thus completing the production of the heat exchange device  20 . 
     3. THIRD EMBODIMENT 
       FIG. 3  is a cross-sectional view showing the constitution of a heat exchange device  30  according to a third embodiment of the present invention. 
     In 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  FIG. 3 , the heat exchange device  30  has a thermoelectric module  30   a  similar to the thermoelectric module  10   a  installed in the heat exchange device  10 . 
     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)  37   a . A pair of terminals  36   a  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  31   a  and non-joint regions  31   b  which project upwardly from gaps between adjacent joint regions  31   a , while the second corrugated fins  34  are constituted of joint regions  34   a  and non-joint regions  34   b  which project downwardly from gaps between adjacent joint regions  34   a . The width x of the joint region  31   a  is larger than the width y of the lower end of the non-joint region  31   b,  while the width x of the joint region  34   a  is larger than the width y of the upper end of the non-joint region  34   b . 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 (Al 2 O 3 ), 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  37   a . 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  31   a  and  34   a  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  31   a  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  34   a  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  37   a  such that P-type and N-type semiconductor compounds thereof are alternately aligned. Thereafter, the leads  38  are soldered to the terminals  36   a  on one end of the heat-absorption electrode  36 , thus completing the production of the heat exchange device  30 . 
     4. FOURTH EMBODIMENT 
       FIG. 4  is a cross-sectional view showing the constitution of a heat exchange device  40  according to a fourth embodiment of the present invention. 
     In the heat exchange devices  10 ,  20 , and  30 , a series of electrodes (e.g. four electrodes in the illustrations of  FIGS. 1 to 3 ) is linearly aligned along the joint regions of the corrugated fins; however, plural electrodes are not necessarily aligned in a single line along the joint regions of the corrugated fins but can be aligned in plural lines. The heat exchange device  40  of the fourth embodiment is designed such that plural electrodes are aligned in two lines along the joint regions of the corrugated fins. As shown in  FIG. 4 , the heat exchange device  40  has a thermoelectric module  40   a  similar to the thermoelectric module  10   a  installed in the heat exchange device  10 . 
     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)  47   a . A pair of terminals  46   a  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  41   a  and non-joint regions  41   b  which project upwardly from gaps between adjacent joint regions  41   a , while the second corrugated fins  44  are constituted of joint regions  44   a  and non-joint regions  44   b  which project downwardly from gaps between adjacent joint regions  44   a . Specifically, as shown in  FIGS. 5A and 5B , four electrodes  43  are aligned in two lines respectively on the joint region  41   a  of the first corrugated fin  41 , while four electrodes  46  are aligned in two lines respectively on the joint region  44   a  of the second corrugated fin  44 . The width “X” of the joint region  41   a  (and  44   a  ) is expressed as X=2x+y, which is larger than the width “x” of the joint region  13   a  in the heat exchange device  10  (similarly the joint regions  21   a  and  25   a  in the heat exchange device  20 , and the joint regions  31   a  and  34   a  in the heat exchange device  30 ) by “x+y”. 
     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 (Al 2 O 3 ), 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  47   a . 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  41   a  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  44   a  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  41   a  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  44   a  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  FIG. 5A , the four heat-dissipation electrodes  43  are aligned in two lines respectively on the joint region  41   a  of the first corrugated fin  41 , while the four heat-absorption electrodes  46  are aligned in two lines respectively on the joint region  44   a  of the second corrugated fin  44 . Nickel plating is applied to the distal ends (i.e. opposite ends in the longitudinal direction) of P-type and N-type semiconductor compounds in the thermoelectric elements  47 . 
     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  47   a . Thereafter, the leads  48  are soldered to the terminals  46   a  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.  FIGS. 6A and 6B  show a variation of the fourth embodiment, i.e. a heat exchange device  40 A in which the four heat-dissipation electrodes  43  are aligned in four lines respectively on the joint region  41   a  of the first corrugated fin  41  and in which the four heat-absorption electrodes  46  are aligned in four lines on the joint region  44   a  of the second corrugated fin  44 . In the heat exchange device  40 A, 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 the joint regions  41   a  and the non-joint regions  41   b  (which project upwardly from gaps between adjacent joint regions  41   a ); and the second corrugated fins  44  are constituted of the joint regions  44   a  and the non-joint regions  44   b  (which project downwardly from gaps between adjacent joint regions  44   a ). In addition, the width “X” of the joint regions  41   a  and  44   a  is expressed as X=4x+3y, which is larger than the width “x” of the joint region  13   a  in the heat exchange device  10  (similar to the joint regions  21   a  and  25   a  in the heat exchange device  20 , and the joint regions  31   a  and  34   a  in the heat exchange device  30 ) by “3x+3y”. 
     5. EVALUATION TESTING 
     (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  40 A as well as the conventionally-known heat exchange device  50  shown in  FIG. 7 . 
     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 ,  40 A, 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. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Test 
                   
                 Insulating Resin Layer 
                 Corrugated Fins 
                 Qmax 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Example 
                 Substrate 
                 Material 
                 Filler 
                 Position 
                 Alignment 
                 (W) 
               
               
                   
               
               
                 A1 
                 One side 
                 Polyimide 
                 Alumina 
                 One side 
                 One line 
                 221 
               
               
                   
                   
                 (One side) 
                 (Substrate) 
               
               
                 A2 
                 One side 
                 Epoxy 
                 Alumina 
                 One side 
                 One line 
                 222 
               
               
                   
                   
                 (One side) 
                 (Substrate) 
               
               
                 B1 
                 None 
                 Polyimide 
                 Alumina 
                 Both sides 
                 One line 
                 221 
               
               
                   
                   
                 (Copper) 
               
               
                 B2 
                 None 
                 Epoxy 
                 Alumina 
                 Both sides 
                 One line 
                 220 
               
               
                   
                   
                 (Copper) 
               
               
                 B3 
                 None 
                 Epoxy 
                 Alumina: 50% 
                 Both sides 
                 One line 
                 223 
               
               
                   
                   
                 (Copper) 
                 AlN: 50% 
               
               
                 C1 
                 None 
                 Epoxy 
                 Alumina 
                 Both sides 
                 One line 
                 225 
               
               
                 C2 
                 None 
                 Epoxy 
                 AlN 
                 Both sides 
                 One line 
                 223 
               
               
                 C3 
                 None 
                 Epoxy 
                 MgO 
                 Both sides 
                 One line 
                 222 
               
               
                 C4 
                 None 
                 Polyimide 
                 Alumina 
                 Both sides 
                 One line 
                 222 
               
               
                 C5 
                 None 
                 Polyimide 
                 AlN 
                 Both sides 
                 One line 
                 220 
               
               
                 C6 
                 None 
                 Polyimide 
                 MgO 
                 Both sides 
                 One line 
                 224 
               
               
                 D1 
                 None 
                 Epoxy 
                 Alumina: 50% 
                 Both sides 
                 Two lines 
                 224 
               
               
                   
                   
                   
                 AlN: 50% 
               
               
                 D2 
                 None 
                 Polyimide 
                 Alumina: 50% 
                 Both sides 
                 Two lines 
                 225 
               
               
                   
                   
                   
                 MgN: 50% 
               
               
                 E1 
                 None 
                 Polyimide 
                 Alumina: 50% 
                 Both sides 
                 Four lines 
                 224 
               
               
                   
                   
                   
                 MgO: 50% 
               
               
                 E2 
                 None 
                 Epoxy 
                 Alumina: 50% 
                 Both sides 
                 Four lines 
                 225 
               
               
                   
                   
                   
                 MgO: 50% 
               
               
                 X 
                 Both 
                 Epoxy 
                 Alumina 
                 One side 
                 One line 
                 208 
               
               
                   
                 sides 
                   
                 (Substrate) 
               
               
                   
               
            
           
         
       
     
     In the measurement, the composition of P-type semiconductor compounds is expressed as Bi 0.4 Sb 1.6 Te 3 , while the composition of N-type semiconductor compounds is expressed as Bi 1.9 Sb 0.1 Te 2.7 Se 0.3 . 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  40 A 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  FIG. 7 , in which the support structures  51  and  56  are each composed of an epoxy resin doped with fillers composed of alumina powder and are each formed with a thickness of 20 μm, thus fabricating the heat exchange device X. 
     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  40 A 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 
               
             
            
               
                   
                   
               
               
                   
                 ACR variations (%) and Qmax variations (%) after thermal cycle 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Test 
                 10,000 
                 20,000 
                 40,000 
                 60,000 
                 80,000 
                 100,000 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Ex. 
                 ACR 
                 Qmax 
                 ACR 
                 Qmax 
                 ACR 
                 Qmax 
                 ACR 
                 Qmax 
                 ACR 
                 Qmax 
                 ACR 
                 Qmax 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 A1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 0 
                 1.2 
                 0.5 
                 1.8 
                 0.5 
               
               
                 A2 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 0 
                 1.1 
                 0.3 
                 1.9 
                 0.5 
               
               
                 B1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 0 
                 1.2 
                 0.4 
                 1.8 
                 0.5 
               
               
                 B2 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 0 
                 1.2 
                 0.3 
                 1.6 
                 0.6 
               
               
                 B3 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0.8 
                 0.2 
                 1.1 
                 0.4 
               
               
                 C1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0.8 
                 0 
                 1.1 
                 0.2 
               
               
                 C2 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0.7 
                 0 
                 1.1 
                 0.2 
               
               
                 C3 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0.8 
                 0 
                 1.1 
                 0.2 
               
               
                 C4 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0.2 
                 0 
                 0.7 
                 0 
                 1.2 
                 0.2 
               
               
                 C5 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0.3 
                 0 
                 0.8 
                 0.2 
                 1.1 
                 0.3 
               
               
                 C6 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 1.1 
                 1.5 
                 1.2 
                 1.8 
                 1.8 
               
               
                 D1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 1.1 
                 1.5 
                 1.5 
                 2.0 
                 2.0 
               
               
                 D2 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 1.1 
                 1.3 
                 1.3 
                 1.6 
                 1.5 
               
               
                 E1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.1 
                 1.1 
                 1.5 
                 1.5 
                 1.7 
                 1.7 
               
               
                 E2 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 1.2 
                 1.2 
                 1.4 
                 1.4 
                 1.3 
                 1.6 
               
               
                 X 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 3.2 
                 5.2 
                 7.1 
                 8.9 
                 12.3 
                 20.2 
               
               
                   
               
            
           
         
       
     
     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  40 A 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 APPLICABILITY 
     All 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.