This application claims the benefit of priority from Japanese Patent Application No. 2009-289557 filed on Dec. 21, 2009, the entire contents of which are incorporated herein by reference.
1. Field
Embodiments discussed herein relate to thermoelectric conversion modules and methods for making the thermoelectric conversion modules.
2. Description of Related Art
Thermoelectric conversion elements may convert wasted thermal energy into electric energy. Because the output voltage of one thermoelectric conversion element is low, a thermoelectric conversion module including a plurality of thermoelectric conversion elements coupled in series may be used.
Related technologies are disclosed in Japanese Laid-open Patent Publication No. H8-43555, Japanese Laid-open Patent Publication No. 2004-288819, Japanese Laid-open Patent Publication No. 2005-5526, and Japanese Laid-open Patent Publication No. 2005-19767, for example.
One aspect of the embodiments, a thermoelectric conversion module includes: p-type semiconductor blocks, each including a p-type thermoelectric conversion material, a first column portion and a first coupling portion that projects in a horizontal direction from an end of the first column portion; and n-type semiconductor blocks, each including an n-type thermoelectric conversion material, a second column portion and a second coupling portion that projects in a horizontal direction from an end of the second column portion, wherein the first coupling portions of the p-type semiconductor blocks are respectively coupled to the other ends of the second column portions of the n-type semiconductor blocks, and the second coupling portions of the n-type semiconductor blocks are respectively coupled to the other ends of the first column portions of the p-type semiconductor blocks, and the p-type semiconductor blocks and the n-type semiconductor blocks are alternately arranged and coupled to each other in series.
The object and advantages of the invention will be realized and achieved by at least the features, elements, and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
A thermoelectric conversion module includes two heat transfer plates that sandwich a plurality of semiconductor blocks including a p-type thermoelectric conversion material (referred to as “p-type semiconductor blocks” hereinafter) and a plurality of semiconductor blocks including an n-type thermoelectric conversion material (referred to as “n-type semiconductor blocks” hereinafter). The p-type semiconductor blocks and the n-type semiconductor blocks are alternately arranged in an in-plane direction of the heat transfer plates and are coupled to each other in series through metal terminals disposed between the semiconductor blocks. Lead electrodes are respectively connected to two ends of the semiconductor blocks coupled in series.
When there is a difference in temperature between the two heat transfer plates, a potential is generated between a p-type semiconductor block and an n-type semiconductor block due to the Seebeck effect, and electric power is output through the lead electrodes. When a power source is coupled to a pair of lead electrodes and electric current is supplied to the thermoelectric conversion module, heat is transferred from one heat transfer plate to the other by the Peltier effect.
The number of pairs of the p-type semiconductor blocks and the n-type semiconductor blocks, for example, several ten to several hundreds of the pairs may be used.
A semiconductor substrate, e.g., a thermoelectric conversion material substrate may be divided to a large number of semiconductor blocks with a dicing saw. The semiconductor blocks are aligned on heat transfer plates to form a thermoelectric conversion module. The metal terminals electrically coupling between the semiconductor blocks include a metal thin film or a conductive paste.
A thermoelectric conversion module 10 includes heat transfer plates 13a and 13b, and p-type semiconductor blocks 11 and n-type semiconductor blocks 12 interposed between the heat transfer plates 13a and 13b. The p-type semiconductor blocks 11 include a p-type thermoelectric conversion material such as Ca3Co4O9, for example. The n-type semiconductor blocks 12 include an n-type thermoelectric conversion material such as Ca0.9La0.1MnO3, for example.
The p-type semiconductor block 11 has a letter-L shape and includes a column portion 11a having a shape of a rectangular prism and a coupling portion 11b that projects in a horizontal direction from an end of the column portion 11a and has a shape of a thin plate. The n-type semiconductor blocks 12 also has a letter-L shape and includes a column portion 12a having a shape of a rectangular prism and a coupling portion 12b that projects in a horizontal direction from an end of the column portion 12a and has a shape of a thin plate.
In the thermoelectric conversion module 10, the coupling portions 11b of the p-type semiconductor blocks 11 are disposed on the heat transfer plate 13a, and the coupling portions 12b of the n-type semiconductor blocks 12 are disposed on the heat transfer plate 13b. The coupling portions 11b of the p-type semiconductor blocks 11 are respectively superimposed on ends (ends remote from the coupling portions 12b) of the column portions 12a of the n-type semiconductor blocks 12. The coupling portions 12b of the n-type semiconductor blocks 12 are respectively superimposed on ends (ends remote from the coupling portions 11b) of the column portions 11a of the p-type semiconductor blocks 11. The p-type semiconductor blocks 11 and the n-type semiconductor blocks 12 are arranged alternately and coupled to each other in series.
The heat transfer plates 13a and 13b each include, for example, a plate-shaped member including a material having good thermal conductivity, such as aluminum or copper. At least the surfaces of the heat transfer plates 13a and 13b, which make contact with the semiconductor blocks 11 and 12, may be subjected to an electric insulating treatment.
In the thermoelectric conversion module 10, the coupling portion 12b of the rightmost n-type semiconductor block 12 may correspond to a lead electrode 14a. An n-type semiconductor thin plate coupling to the column portion 11a of the leftmost p-type semiconductor block 11 may correspond to a lead electrode 14b.
When a temperature difference is created between the heat transfer plates 13a and 13b, current flows between the p-type semiconductor blocks 11 and the n-type semiconductor blocks 12, and power may be output from the lead electrodes 14a and 14b. The thermoelectric conversion module 10 may be used as a peltier element. For example, when the voltage is applied to the lead electrodes 14a and 14b, the heat transfers from the heat transfer plate 13a to the heat transfer plate 13b or vise versa.
In operation S11, as illustrated in
The thickness of the p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 may be 900 μm. The p-type semiconductor substrate 21 may include Ca3Co4O9 and the n-type semiconductor substrate 22 may include Ca0.9La0.1MnO3. The p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 may include other thermoelectric conversion materials. The p-type thermoelectric conversion material may include NaxCoO2 or Ca3-xBixCo4O9, for example. The n-type thermoelectric conversion material may include La0.9Bi0.1NiO3, CaMn0.98Mo0.02O3, or Nb-doped SrTiO3, for example.
In operation S12, as illustrated in a plan view of
Referring to
Incisions (grooves) forming a grid pattern and having a depth of about 800 μm are formed in the n-type semiconductor substrate 22 so as to form column portions 12a of the n-type semiconductor blocks 12. The size of the column portions 12a may be 100 μm×100 μm, the height may be 800 μm, and the intervals between the column portions 12a may be 200 μm. The column portions 11a and 12a are formed by forming the incisions in the semiconductor substrates 21 and 22 with a dicing saw. Alternatively, for example, grooves may be formed in the semiconductor substrates 21 and 22 by blasting so as to form the column portions 11a and 12a.
In operation S13, as illustrated in
As illustrated in
Referring now to
In operation S14, as illustrated in
In
As illustrated in
In order to investigate the thermo-electric characteristics of the thermoelectric conversion module, the size of the thermoelectric conversion module may be set to about 2 mm×about 2 mm in size and about 1 mm in thickness. The number of the p-type semiconductor blocks 11 and the number of the n-type semiconductor blocks 12 may each be 100 (100 pairs). The temperature of one of the heat transfer plates of the thermoelectric conversion module may be set to room temperature and the temperature of the other heat transfer plate may be set to be 10° C. lower than the room temperature. Under such conditions, a voltage of about 0.1 V was generated between the output terminals.
In the thermoelectric conversion module 10, as illustrated in
The thermoelectric conversion module 10 illustrated in
In contrast, a thermoelectric conversion module 30 illustrated in
As illustrated in
Referring to
As illustrated in
As illustrated in
For example, the p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 are heat-treated at 700° C. to 900° C. to bond the p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 through the metal layers 31 to form a bonded substrate 35. The strong pressure may not be applied to the semiconductor substrates 21 and 22. The pressure may be sufficient to increase the bonding strength. The p-type semiconductor substrate 21 may be bonded to the n-type semiconductor substrate 22 through hot pressing by heating at 900° C. to 1000° C. while applying a pressure of about 10 MPa to 50 MPa.
The bonded substrate 35 is cut into pieces of a desired size. A dicing saw or the like forms incisions in the thin-plate portions of the p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 so that the p-type semiconductor blocks 11 and the n-type semiconductor blocks 12 are alternately arranged and coupled to each other in series, thereby forming a semiconductor block assembly. The heat transfer plates 13a and 13b are attached to the semiconductor block assembly with, for example, a heat-conducting adhesive, to form the thermoelectric conversion module 30 illustrated in
The metal layers 31 may reduce diffusion of atoms between the p-type semiconductor blocks 11 and the n-type semiconductor blocks 12 and improve the reliability of the joints between the semiconductor blocks 11 and 12.
The depth of the incisions may vary during formation of the incisions (grooves) with a dicing saw. However, since the p-type semiconductor substrate 21 is bonded to the n-type semiconductor substrate 22 through the metal layers 31, such a variation in depth may be compensated by the metal layers 31 working as a cushioning material. As a result, the connection between the p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 may be ensured, and the reliability of the joints between the semiconductor blocks 11 and 12 may be improved.
Prior to bonding the p-type semiconductor substrate 21 to the n-type semiconductor substrate 22, a silver paste may be applied on the metal layers 31. This may help ensure the connection between the p-type semiconductor substrate 21 and the n-type semiconductor substrate 22 even when the variation in depth of incisions is great. Alternatively, the metal layers 31 may not be formed and a conductive bonding layer including a conductive material such as a silver paste may be formed on the column portions 11a and 12a prior to bonding of the p-type semiconductor substrate 21 to the n-type semiconductor substrate 22.
The size of the thermoelectric conversion module may be about 2 mm×about 2 mm and the thickness may be about 1 mm. The number of the p-type semiconductor blocks 11 and the number of the n-type semiconductor blocks 12 may each be 100 (100 pairs). The temperature of one of the heat transfer plates of the thermoelectric conversion module may be set to room temperature and the temperature of the other heat transfer plate may be set to be 10° C. lower than the room temperature. A voltage of about 0.1 V may be generated between the output terminals.
The bonded substrate 25 is prepared by bonding the p-type semiconductor substrate 21 to the n-type semiconductor substrate 22 as illustrated in
The bonded substrate 25 is then pulled out from the resin bath and the resin is cured. In operation S13b, the resin adhering onto the outer side of the bonded substrate 25 is removed by polishing or the like. The subsequent processes may be substantially the same or similar to those of the method illustrated in
Number | Date | Country | Kind |
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2009-289557 | Dec 2009 | JP | national |