JP4512692B2 - Thermoelectric element-based cooling method and apparatus - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a thermoelectric element-based cooling method and apparatus using a Peltier effect that occurs in a joining portion of dissimilar metals, and in particular, an electron at an arbitrary position using the Peltier effect that occurs in a portion where metals are joined via a semiconductor. The present invention relates to a cooling method using a thermoelectric element suitable for cooling a circuit element, a microreactor, and the like and a cooling device using the cooling method.

  When heat is generated by the operation of various devices, it is indispensable to perform cooling in order to function efficiently and not to cause functional damage. The cooling means is adopted.

  While recent advances in semiconductor technology have made it possible to incorporate many circuits in small elements, electronic devices such as high-density circuit elements such as CPUs generate more heat, and these are caused by heat. Degradation or damage of the device occurs.

  Conventionally, as a countermeasure, a cooling fan is driven to forcibly replace the surrounding air, and heat radiation fins are provided on the back surface of the circuit element substrate to circulate cooling air in a concentrated manner. I am doing so. In particular, laser light emitting diodes generate a lot of heat, and as the output increases, more heat is generated. Therefore, in addition to cooling the diode element and the substrate including its drive circuit by the above-mentioned means, Depending on the case, cooling may be performed.

  Such cooling means must be increased in size in the structure part of the radiating fin, the structure part of the cooling fan, etc., the entire apparatus including the electronic device is increased in size, and there is a problem that noise is generated by driving the cooling fan. there were. As a countermeasure, a thermoelectric material of a semiconductor composed of a specific component is used, and cooling is performed by bringing the cooling side by the Peltier effect caused by the energization into contact with the electronic device as described above. By using such a thermoelectric element, there are various merits such as small size, silence, long life, no maintenance, no waste, power generation by waste heat, cooling without chlorofluorocarbon, and many thermoelectric conversion elements have been studied. ing.

However, conventionally used thermoelectric materials are made of bulk materials, and there is a limit to miniaturization. As a countermeasure, for example, as shown in Japanese Patent Laid-Open No. 63-76463, it has been proposed to reduce the thickness of a thermoelectric element that generates the Peltier effect. Further, for example, as shown in Japanese Patent Laid-Open No. 6-318738, this thin film There has also been proposed a structure in which a large amount of current can be passed by stacking thermoelectric elements.
JP 63-76463 A JP-A-6-318738

The cooling of electrical devices is important as described above, and the cooling means is indispensable, and it is proposed to use a thin film Peltier thermoelectric element to reduce the size, but the Peltier effect For example, as described in JP-A-6-318736, a thermoelectric element that generates a P-type semiconductor metal oxide of Cu ₂ O, NiO, Mn ₂ O ₃ , ZnO, MoS, Fe ₃ O ₄ , FeO, CuO N-type semiconductor metal oxides and the like are used, and the production thereof requires a lot of work as described in the publication and requires advanced semiconductor manufacturing techniques.

  In recent years, technology development for forming a microscale reaction vessel, an analysis channel, or the like on a substrate such as silicon or glass by using a semiconductor microfabrication technique has been performed. The microchip manufactured in this way enables reaction analysis with higher speed and higher accuracy than before due to an effect such as an increase in the surface area / volume ratio, and a compact and automated system can be realized.

  It is attracting attention that such a system is established as a field of bio-chemical reaction technology in the future. At that time, it is necessary to carry out the reaction under predetermined conditions in the above-mentioned minute region. Therefore, it is important to control the temperature in the minute region. In particular, high-coherent solid-state lasers require high heat flux heat removal that exceeds the boiling limit heat flow rate by several orders of magnitude. Even in these technical fields, the temperature control means by the cooling device using the Peltier effect is effective in terms of downsizing and ease of temperature control, but even in that case, a more compact cooling means is necessary, and its development Is expected.

  In order to solve the above problems, the present inventors have proposed a technique as shown in Japanese Patent Application No. 2001-336940. Since the present invention is a technology developed by causing the endothermic action to be performed based on the same principle as the above-described technology, the part related to the basic principle of the present invention described in the first application will be described.

  When two kinds of metals are brought into contact with each other, due to the difference in the work function and the number of free electrons of each metal, electrons move from one metal to the other in a direction to fill the difference, and a potential difference occurs between the two metals. The electricity generated in this way is a contact potential, and when the contact of two kinds of metals is heated, the movement of free electrons becomes active, and exchange is performed between thermal energy and electrical energy, resulting in a thermoelectric effect. In this thermoelectric effect, both ends of two kinds of metals are connected to each other, and the Seebeck effect in which an electromotive force is generated by maintaining both connecting portions at different temperatures, and conversely, both ends of the two kinds of metals are connected to each other. It is known that there is a Peltier effect in which heat is generated or endothermic in addition to Joule heat when current is passed.

  When examining the surface potential distribution model when different kinds of metals are connected as described above, when using gold and platinum connected to each other in a linear form, the case of such a contact-type thin film thermoelectric element A surface potential distribution model as shown in FIG. 7 is conceivable. That is, the potential in the gold / platinum thin film becomes a potential as shown by a solid line A in FIG. 7 in consideration of the work functions of gold and platinum. The gold and platinum thin films each have a resistance, and the surface potential is as shown by the dotted line B because the potential has an inclination. In addition, considering the fact that electrons move from the gold thin film and the gold thick film to the platinum thin film due to the rearrangement of electrons in the gold / platinum junction, the chemical potentials in the gold / platinum junction match. It is considered that the potential distribution is as indicated by the alternate long and short dash line C.

  FIG. 7A shows the energization from the gold thin film to the platinum thin film, and FIG. 7B shows the energization from the platinum thin film to the gold thin film. It is apparent that the potential is increased by ΔVp at the point D when the energization is performed from the platinum thin film to the gold thin film than when the energization is performed from the gold thin film to the platinum thin film. From this, it can be seen that the surface potential distribution model is qualitatively consistent with the potential difference on the platinum side by surface potential distribution measurement, and the surface potential distribution model considering the potential by Fermi rank is correct.

  FIG. 8 shows a surface potential distribution model of a junction type thin film thermoelectric element in which gold and platinum are formed so as to overlap each other. In this case as well, the films are formed in the same manner as described above and have an overlap of about 1 mm. In this case, as in the case of the contact type, if a potential distribution model that takes into account the potential difference due to the Fermi rank is created, an endothermic process is performed at the junction when the gold thin film is energized to the platinum thin film. It can be seen that there is also the possibility of endotherm in the gold thick film when the platinum thin film is energized from the gold thin film.

  In the previous application, it was made on the basis of such a basic principle. FIG. 9A shows the first metal A thin film 1, the metal B thin film 2, and the second metal A thin film 3, and the semiconductor thin film 4 to each other. 5 schematically shows an example in which a cooling device composed of a dissimilar metal thin film connector is formed through connection.

  When actually manufacturing this cooling device, the first metal A thin film 1 and the second metal A thin film 3 are made of gold in the same manner as described above, and the metal B thin film is made of platinum. Although the thickness of this thin film can be set arbitrarily, a thickness of about 500 to 4000 mm is used as in the experimental example. Further, the width can be arbitrarily set, but a width of about 4 mm can be used as in the above embodiment.

  In the previous application, the semiconductor thin films 4 and 5 are provided in the portion where two kinds of metals are joined, so that the metal potential distribution can be maintained between the two metals to be joined. Note that this semiconductor is different from the conventional semiconductor for achieving the Peltier effect and is merely used to cut off the continuous flow of electrons. Therefore, each semiconductor may be a P-type semiconductor or an N-type semiconductor, and if one of them is a P-type semiconductor and the other side is an N-type semiconductor, the operation is the same. However, it is preferable that each semiconductor has a work function intermediate between that of metal A and metal B.

  In the cooling device using the dissimilar metal thin film connector as described above, when the work function is viewed, as shown in FIG. 9 (b), it is basically a concave type in the figure due to the difference in work functions of metal A and metal B. In the middle of this, there is a characteristic that a small step is generated in the height portion of the work function of the semiconductors 4 and 5. The difference in height between the small steps is the difference in work function between the two semiconductors. When the same semiconductor is used for both semiconductors, the heights of the two semiconductors coincide.

  When a current i is applied to such an apparatus as shown in FIG. 9C, a voltage change as shown in FIG. 9 occurs as a potential difference corresponding to the work function, and the second metal A thin film 3 The metal B thin film 2 generates heat and the metal B thin film 2 and the first metal A thin film 1 endotherm. Corresponding to this characteristic, the surface potential in consideration of the actual resistance of each thin film has a characteristic as shown in FIG.

  When actually manufacturing a cooling device comprising a dissimilar metal thin film connector based on the above principle, for example, as shown in FIG. 10A, a metal B thin film 11 is formed on a silicon substrate 10 and both ends thereof are formed. The first semiconductor thin film 12 and the second semiconductor thin film 13 are formed, the first metal A thin film 14 is formed so that the end is located on the first semiconductor thin film 12, and the end is formed on the second semiconductor thin film 13. The second metal A thin film 15 is formed so as to be positioned. Each metal can be selected arbitrarily, but the metal A may be set to gold and the metal B may be set to platinum as described above, or the first semiconductor and the second semiconductor may be P-type semiconductors. Alternatively, an N-type semiconductor may be used, and one of them may be a P-type semiconductor and the other side may be an N-type semiconductor.

  When such a cooling device is applied to an actual device, as shown in FIG. 10B, an electric current is passed in a direction in which an endothermic action is performed between the first metal A thin film 14 and the metal B thin film 11. In this state, the electronic element 16 to be cooled is formed or placed at the end position of the first metal A thin film 14. As a result, the electronic element 16 is cooled, and the cooling capacity is controlled by controlling the amount of current supplied to the cooling device, so that the temperature of the electronic element can be controlled.

  With the above-mentioned technology applied earlier, the endothermic part can be spatially independent, and more current can be flowed by stacking the endothermic part of the thin film separating thermoelectric element. , Cooling capacity increases, cooling capacity increases. For this reason, the application to the local high heat flux removal technique of a semiconductor element, the active control technique of a forced convection heat transfer surface, etc. came to be expected. After that, the present invention was obtained as a result of further research aimed at making it possible to cool various members more easily and more easily applied to an actual apparatus.

In order to solve the above-described problem, the thermoelectric element-based cooling method according to the present invention is configured such that the ends of the n-type semiconductor and the p-type semiconductor are joined to both ends of the first metal so as to be spaced apart from each other. The second metal is joined to the other end of the p-type semiconductor, and all of the metals are metals of different work functions. The metal electrode that is the positive electrode is the second metal having the highest work function. Joined to metal, then joined to the end of the first metal, which is the next largest work function metal, with the n-type semiconductor in between, and then sandwiched the p-type semiconductor in the other end of the first metal A third metal, which is the metal having the smallest work function, is joined to a metal electrode which is a negative electrode, and the n-type semiconductor, the first metal, and the p-type semiconductor are joined from the second metal. And a junction that conducts heat by energizing the other electrode through the third metal. By is obtained to perform the cooling action.

  In another thermoelectric element-based cooling method according to the present invention, at least the first metal is a thin film in the thermoelectric element-based cooling method.

  According to another thermoelectric element-based cooling method of the present invention, any one of the n-type semiconductor and the p-type semiconductor on the heat absorption side of the thermoelectric element-based cooling method is arbitrarily heated by the first metal or the lead wire. It is arranged at the place.

In the thermoelectric element-based cooling device according to the present invention, the ends of the n-type semiconductor and the p-type semiconductor are joined to both ends of the first metal so as to be separated from each other, and the second metal is attached to the other end of the n-type semiconductor. , A semiconductor isolation member formed by joining a third metal to the other end of the p-type semiconductor, and the metals are all kinds of metals having different work functions. Joined to a large second metal, then joined to the end of the first metal, which is the next largest work function metal, with an n-type semiconductor in between, and then a p-type semiconductor to the other end of the first metal A third metal, which is a metal having the lowest work function, is bonded to the third metal, and is bonded to a metal electrode that is a negative electrode. The n-type semiconductor, the first metal, Junction where the third metal is energized through a p-type semiconductor to absorb heat It is obtained to perform the more cooling.

  In another thermoelectric element-based cooling device according to the present invention, at least the first metal is a thin film in the thermoelectric element-based cooling device.

  According to another thermoelectric element-based cooling device of the present invention, in the thermoelectric element-based cooling device, any one of the n-type semiconductor and the p-type semiconductor may be heated arbitrarily by the first metal or the lead wire. It is arranged at the place.

  Further, another thermoelectric element-based cooling device according to the present invention incorporates the thermoelectric element-based cooling device into any of a laser transmitter, a semiconductor integrated circuit, a computer, a reactor, a heat exchanger, a machine tool, and a mobile phone. Is.

  The present invention has been made by conducting various experiments following the invention of the previous application by the present inventors as described above, and will be described along the course of the experiments.

  First, metal electrodes were connected in series with the upper and lower end surfaces of the semiconductor to produce a simulated thin film separation type thermoelectric element. The experiment was performed using three types of sample metals, Cu, Pt, and Pb, as the endothermic ends.

The electrode copper plate had a length of 30 mm, a width of 2.5 mm, and a thickness of 1 mm in order to suppress Joule heat of the electrode copper plate. For the semiconductor part, a commercially available bismuth tellurium-based semiconductor was used. The semiconductor is a cube having a side of 2 mm. The temperature distribution was measured using a radiation thermometer, assuming that the emissivity was constant. The outline of the experimental apparatus and the operating state are shown in FIG. In FIG. 1, the portions indicated as N and P mean n-type and p-type semiconductors, respectively. As shown in the figure, the experiment was conducted with a configuration of Cu (positive electrode) -n-type semiconductor-sample metal-p-type semiconductor-Cu (negative electrode). In order to align the heat generation end and the heat absorption end in one direction, a current is passed from the n-type to the p-type. At this time, the upper end has endotherm Q _h, heat generation Q _c occurs at the lower end.

  The performance of the thermoelectric element created this time is shown in FIG. When Cu plate was used as the sample metal, there was a maximum temperature drop of 10.2 ° C. at 24 mA. When the current was increased, the temperature drop was becoming saturated with an increase in Joule heat, so an experiment was conducted at 15 mA. Furthermore, by using bismuth tellurium type n-type and p-type semiconductors with higher electrical conductivity, a maximum temperature drop of 31 ° C. is realized with respect to a potential of 8 A, and the temperature drop increases up to 8 A. Continuing, experimental results that did not reach the maximum were also obtained.

  In FIG. 3, a copper material is used as an electrode, and a current of 15 mA is applied to a combination of Cu—Pt—Cu, Cu—Cu—Cu, Cu—Pb—Cu, and Pt—Au—Ag, Ag—Au—Pt. Shows the temperature distribution. With the Cu—Pt—Cu combination in (a), the n-type has a cooling effect about 4 ° C. larger than that of the p-type, and generates heat at the connection between the Cu electrode and the semiconductor. It can be seen that a sufficient cooling heat amount at the time exerts a cooling effect on those portions.

  Next, in the combination of Cu—Cu—Cu in FIG. 3B, the temperature is lowered by about 8 ° C. from room temperature. Moreover, the temperature of both semiconductors itself hardly changes, and is about 2 ° C. lower than room temperature. Further, there was not much difference in temperature drop between n-type and p-type. In the combination of Cu—Pb—Cu in (c), comparing the temperature difference between the two semiconductors, it can be seen that the p-type has a larger cooling effect by about 2 ° C. In addition, heat generation at the contact portion between the Cu electrode plate and the semiconductor is adjusted in the same manner as when Pt is used. Further, regarding the work function of Cu as a reference, it is considered that the n-type semiconductor has a larger cooling effect than when using Pt having a large work function. It can also be seen that the p-type has a greater cooling effect when a conducting wire having a work function smaller than that of Cu is used. Further, when Pt is used, the cooling effect extends to a portion where heat is considered to be generated, and the entire n-type semiconductor can be cooled. FIGS. 3D and 3E show the results of further experiments by the inventor. FIG. 3D shows the experimental results of the Pt—Au—Ag combination, and FIG. 3E shows the Ag—Au—Pt combination. These also show that the same effects as those in the previous combination can be obtained.

  The difference in the above cooling characteristics can be explained by the potential diagram seen from the electrons shown in FIG. The work functions are Pt: 5.65 eV, Cu: 4.65 eV, and Pb: 4.25 eV, respectively. This work function difference corresponds to the value of the Schottky barrier at the junction between the semiconductor and the metal. When energized, electrons are p-type and the n-type has a larger endothermic amount than the electrons move upward. In the case of Cu, there is no difference in the amount of endotherm because the amount of movement is almost the same for p-type and n-type. In the case of Pb, since the potential difference is larger in the p-type than in the n-type, it can be explained that the endothermic amount increases.

  If this principle is used, the phenomenon that the semiconductor part is cooled as a whole in the vicinity of the n-type semiconductor when using Pt and the vicinity of the p-type semiconductor when using Pb can be explained. Further, in the metal material connecting the n-type semiconductor and the p-type semiconductor, the portion connecting the two semiconductors can be a lead wire having an arbitrary length, and therefore the cooling portion can be easily disposed at an arbitrary position. it can. The above experiment also demonstrates that the entire n-type semiconductor is cooled in the case of Pt and Cu, and the entire semiconductor on one side can be cooled.

  FIG. 5 shows the time characteristics of the cooling effect of the semiconductor end portion on the endothermic portion side. The endotherm was calculated using the gradient in the figure. The endothermic amount of the thin film separated thermoelectric element used in the experiment was about 16.5 mW when calculated by multiplying the temperature change per unit time by the mass of the endothermic portion of the semiconductor and the specific heat. Further, the difference in work function of different metals is about 1 eV at the maximum, and it can be estimated that cooling of the order of 1 V corresponding to 1 eV occurs in consideration of the potential difference in the semiconductor portion. Since the current value during the experiment is 15 mA, the endothermic amount that can be expected from the work function is about 15 mW. This agrees quantitatively well with the endothermic amount obtained in this experiment, indicating that the present invention can be used as theoretically. Similarly, when 5 A was applied, the endothermic amount was about 1 W.

  As can be seen from this principle, the above example shows an example in which a thin film metal is used as a metal bonded to at least an n-type semiconductor and a p-type semiconductor. However, any metal can be used without being limited to a thin film metal. Also, the semiconductors can be connected by lead wires. In addition, as an electrode bonded to the other end of each semiconductor, for example, a metal bonded to the end of the n-type semiconductor and the p-type semiconductor is a first metal, and a metal bonded to the other end of the n-type semiconductor is a second metal, When the metal bonded to the other end of the p-type semiconductor is a third metal, the electrodes are connected to the second metal and the third metal, respectively, and a positive or negative potential is applied to these electrodes. In this case, the same effect can be produced. In such a configuration, in the above example, Pt, Cu, and Pb are used as the first metal, and Cu is used as the second metal and the third metal.

As this metal combination, for example, as shown in FIG. 6A, Ag is used as the first metal, Pt is used as the second metal, Ag is used as the third metal, and a Cu lead wire is connected to the power source. Cu (positive electrode) -Pt-n type semiconductor-Au-p type semiconductor-Ag-Cu (negative electrode) connection structure, or Cu as the first metal as shown in FIG. Pt is used as the metal, Pb is used as the third metal, and similarly connected to the power source with a Cu lead wire, such as Cu (positive electrode) -Pt-n type semiconductor-Cu-p type semiconductor-Pb-Cu (negative electrode). It has been found that the cooling effect is large when the connection structure is made to be low and the work function is continuously reduced.

  The cooling method and apparatus using a dissimilar metal thin film connector according to the present invention can be effectively used as an electronic element, for example, for cooling a semiconductor laser element. Therefore, it can be used in a wide range of fields such as cooling of a microscale reactor used for the purpose.

  Since the cooling method according to the present invention is configured as described above, the entire semiconductor on one side can be cooled in the same manner as the technique previously proposed by the present inventors, and the n-type and p-type semiconductors can be spatially separated. By separating, the cooling part can be spatially independent. At that time, the thin film junction warriors of both semiconductors can be connected by lead wires, and the degree of freedom is further increased. Therefore, a wide range of applications such as local high heat flow rate removal technology of semiconductor elements and active control technology of forced convection heat transfer surfaces are possible. In particular, in a metal material that connects an n-type semiconductor and a p-type semiconductor, a portion connecting the two semiconductors can be a lead wire having an arbitrary length, and thus the cooling portion can be easily disposed at an arbitrary position. it can.

  In particular, by selecting metal electrode materials having different work functions and arbitrarily selecting the direction of current flow, a cooling effect can be arbitrarily generated in any part of the n-type semiconductor and the p-type semiconductor. Therefore, application to an actual apparatus becomes easier, and various members can be cooled more efficiently.

  In addition, since the cooling effect almost quantitatively matches the value calculated by the model considering the work function difference of the metal, an appropriate cooling effect corresponding to each application can be set and designed.

  The cooling device according to the present invention can perform a cooling action using the Peltier effect generated only by connecting a metal thin film through a semiconductor, and can be easily manufactured only by using a simple semiconductor manufacturing technique, Since it can be extremely miniaturized, it can be applied compactly and easily as a cooling device for various members including a very small electronic member.

  In particular, the cooling device according to the present invention can be effectively incorporated into a laser transmitter, a semiconductor integrated circuit, a computer, a reactor, a heat exchanger, a machine tool, a mobile phone, and the like.

FIG. 1 is a diagram showing an outline of an operating state and an experimental apparatus in a basic configuration of an embodiment of the present invention.
FIG. 2 is a performance diagram of a simulated thin-film separation type thermoelectric element when the sample metal is Cu.
FIG. 3 is a diagram showing the results of measuring the temperature distribution using various metal materials in the present invention.
FIG. 4 is an electron potential diagram of a thermoelectric element in which the work function is changed according to the present invention.
FIG. 5 is a graph showing the maximum temperature drop of the sample metal when the current value is 15 mA.
FIG. 6 is a diagram showing another embodiment of the present invention.
FIG. 7 is a diagram showing a surface potential distribution when end portions of a metal film are line-connected to each other.
FIG. 8 is a diagram showing a surface potential distribution when the end portions of the metal film are superposed on each other and are in contact with each other.
FIG. 9 is a diagram showing the basic configuration and various characteristics of the embodiment of the present invention and the principle of cooling action.
FIG. 10 is a cross-sectional view of a cooling device according to the present invention, in which (a) shows a basic configuration of the cooling device and (b) shows a state in which an electronic element is cooled by the cooling device.

Claims (7)

Ends of the n-type semiconductor and the p-type semiconductor are joined to both ends of the first metal so as to be spaced apart from each other, a second metal is attached to the other end of the n-type semiconductor, and a third is attached to the other end of the p-type semiconductor. Joining metal,
The metals are all kinds of metals having different work functions. The metal electrode as the positive electrode is joined to the second metal having the highest work function, and then the n-type semiconductor is sandwiched between the metals having the next highest work function. Joining to the end of a certain first metal, then joining the other end of the first metal to a third metal having the smallest work function with a p-type semiconductor in between, and Bonded to the metal electrode that is an electrode,
A thermoelectric element characterized in that the second metal is energized to the other electrode through the n-type semiconductor, the first metal, the p-type semiconductor and the third metal, and a cooling operation is performed by a joint portion that performs an endothermic operation. Use cooling method.   The thermoelectric element-based cooling method according to claim 1, wherein at least the first metal is a thin film.   2. The method of cooling using a thin film separated thermoelectric element according to claim 1, wherein one of the n-type semiconductor and the p-type semiconductor has an endothermic side disposed at an arbitrary heat generation location by the first metal or the lead wire. . Ends of the n-type semiconductor and the p-type semiconductor are joined to both ends of the first metal so as to be spaced apart from each other, a second metal is attached to the other end of the n-type semiconductor, and a third is attached to the other end of the p-type semiconductor. It consists of a semiconductor isolation member formed by joining metals,
The metals are all kinds of metals having different work functions. The metal electrode as the positive electrode is joined to the second metal having the highest work function, and then the n-type semiconductor is sandwiched between the metals having the next highest work function. Joining to the end of a certain first metal, then joining the other end of the first metal to a third metal having the smallest work function with a p-type semiconductor in between, and Bonded to the metal electrode that is an electrode,
A thermoelectric element-based cooling device, wherein electricity is supplied from the second metal to the third metal through the n-type semiconductor, the first metal, and the p-type semiconductor, and cooling is performed by a joint portion that performs an endothermic action.   The thermoelectric element-based cooling device according to claim 4, wherein at least the first metal is a thin film. The thin-film-separated thermoelectric element-based cooling device according to claim 4 , wherein the heat absorption side of one of the n-type semiconductor and the p-type semiconductor is arranged at an arbitrary heat generation location by the first metal or lead wire. . Said thermoelectric element utilizing cooling device, a laser transmitter, a semiconductor integrated circuit, computer, reactor, heat exchanger, a machine tool, any of claims 4 to 6, characterized in that incorporated in one of the mobile phone The thermoelectric element utilization cooling device as described in any one.

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