JP3520606B2 - Peltier module - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Peltier module composed of a plurality of Peltier devices.

[0002]

2. Description of the Related Art A plurality of Peltier elements, which are thermoelectric conversion elements, are arranged side by side between a pair of substrates, and the Peltier elements are electrically connected in series by joining the Peltier elements to the bonding electrodes provided on each substrate. In addition, in the Peltier module that is connected and arranged so as to be thermally parallel, one substrate acts as a heating side and the other substrate acts as a cooling side, which results in thermal expansion and contraction of both substrates. Due to the thermal expansion and thermal contraction, thermal stress is applied to the joint between the substrate and the Peltier element in the direction parallel to the joint surface. A heat exchange member is tightly fixed to each substrate, and the difference in thermal expansion coefficient between the heat exchange member and the substrate further increases the thermal stress. Such thermal stress lowers the performance of the Peltier module and also lowers the reliability of the joint. Occasionally, fatigue failure of the joint and destruction of the Peltier element are also caused.

For this reason, in the one disclosed in Japanese Utility Model Laid-Open No. 62-51770, a heat exchange member, which is closely fixed to the substrate on the thermal expansion side, is provided with a thermal stress absorbing portion for absorbing thermal stress by deformation. Things have been done.

[0004]

However, the thermal stress absorbing portion in the above structure is provided outside the joining region of the heat exchange member with the substrate, and reduces the thermal stress acting between the Peltier element and the substrate. Was almost ineffective. The present invention has been made in view of the above points, and an object of the present invention is to provide a Peltier module in which the reliability of the joint between the Peltier element and the substrate against thermal stress is further improved.

[0005]

SUMMARY OF THE INVENTION However, the present invention provides a Peltier module in which a plurality of Peltier elements are arranged side by side between a pair of substrates, and the Peltier elements are joined to the joining electrodes provided on the respective substrates. The substrate on which the bonding electrodes are provided is characterized mainly in that a thermal stress absorbing portion that deforms according to thermal stress is provided between the Peltier element bonding portions of the Peltier device mounting portion.

As the thermal stress absorbing portion here, a protrusion formed between the Peltier element joint portions can be preferably used.
It is more preferable if this projection also serves as an array positioning member for the Peltier elements. Further, the present invention provides a Peltier module in which a plurality of Peltier elements are arranged side by side between a pair of substrates whose heat exchange members are fixed to the respective outer surfaces, and the Peltier elements are joined to the joining electrodes provided on each substrate. The heat exchange member is closely fixed in the heat exchange member mounting area on the outer periphery of the Peltier element mounting area of the substrate, and a minute gap is provided between the outer surface of the Peltier element mounting area of the substrate and the heat exchange member. It has other characteristics in that

[0007]

According to the present invention, since the thermal stress absorbing portion that deforms in response to thermal stress is provided between the Peltier element joining portions of the Peltier element mounting portion of the substrate, the thermal stress absorbing portion is formed between the substrate and the Peltier element. Reliably absorbs the thermal stress that acts during.
At this time, if a ridge formed between the Peltier element joints is used as the thermal stress absorber provided on the substrate, the thermal stress absorber can be easily formed. If it also serves, it is possible to improve the assemblability.

Further, the heat exchange member is closely attached and fixed in the heat exchange member mounting region on the outer periphery of the Peltier device mounting region of the substrate, and a minute gap is provided between the outer surface of the Peltier device mounting region of the substrate and the heat exchange member. However, in order to allow the gap to bend due to the thermal expansion and contraction of the substrate, the heat applied to the joint between the substrate and the Peltier element is increased.
The stress can be reduced and thus the problems due to thermal stress can be practically eliminated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiments. As shown in FIG. 1, the Peltier module shown here includes a plurality of Peltier elements 1, a pair of substrates 2, 2 and a tubular seal. The frame 3 and the pair of substrates 2 and 2 at the four corners of the substrate 2
It is composed of a cylindrical support column 4 connecting the two.

In each Peltier element 1, a P-type element and an N-type element are sequentially connected in a π-type by a junction electrode 10 formed on the opposing surfaces of the substrates 2 and 2, so that they are electrically connected in series. Thermally connected in parallel. Further, both ends of the series circuit formed of the bonding electrode 10 and the Peltier element 1 on each substrate 2 are provided on the facing surfaces of each substrate 2 and provided with terminal portions 12 for connection to the outside. It is connected to the lead electrode 11.

FIG. 5 shows one substrate 2 and FIG. 6 shows the other substrate 2. The positions of the bonding electrodes 10 on the two substrates 2 are displaced due to the series connection of the Peltier devices 1. Further, as is apparent from the drawing, the lead electrode 11 provided on each substrate 2 is formed as an annular one that forms a closed loop surrounding the arrangement portion of the bonding electrode 10, that is, the arrangement portion of the plurality of Peltier elements 1. There is.

The above-mentioned substrate 2 having at least a surface having electrical insulation property is a simple substance such as alumina or aluminum nitride, or aluminized surface of aluminum, or an alumina or silicon oxide layer on the surface of aluminum. Is formed of a composite material such as a copper foil or a thin adhesive insulating layer formed on the surface of copper, and the bonding electrode 10, the lead electrode 11, the terminal portion 12 and the like are formed by, for example, a thermal spraying method on the surface of the substrate 2. Has been done.

The seal frame 3 is for sealing the portion where the Peltier element 1 is arranged, and is formed in a cylindrical shape with an insulating material such as ABS resin or non-hydrophilic treated paper. The opening edge is joined to the closed loop portion of the lead electrode 11 of each substrate 2, so that the space for arranging all the Peltier devices 1 together with the substrates 2 and 2 is sealed to prevent moisture. Here, the seal frame 3 and the lead electrode 11 are bonded to each other by previously forming a metal film of copper, nickel, tin or the like on the portion of the seal frame 3 to be bonded to the lead electrode 11 by plating or thermal spraying. The lead electrodes 11 are joined by brazing or soldering. This is to avoid the use of an adhesive that easily allows moisture to enter in the long term. The seal frame 3 here also bears a load in the direction in which the substrates 2 and 2 face each other.

Each of the cylindrical columns 4 is formed of, for example, fiber plastic having a low thermal conductivity, and metal films 40 of copper, nickel, tin or the like are formed on both ends thereof by plating or thermal spraying. Similar to the case of the seal frame 3, the metal portion 13 provided on the substrate 2 side by thermal spraying or the like is joined by brazing or soldering. The metal portion 13 is insulated from the lead electrode 11.

The Peltier element 1 is not directly bonded to the bonding electrode 10, but is bonded to the bonding electrode 10 via a relaxation member 15 for relaxing thermal stress.
The relaxation member 15 is made of a material having a high electric conductivity and a high thermal conductivity and a Young's modulus almost equal to that of the Peltier element 1, for example, annealed copper, and both surfaces of the Peltier element 1 are preliminarily plated with a harmless metal. The peltier element 1 is sandwiched between the pair of easing members 15 and 15 by soldering the easing member 15 plated with nickel, gold, solder or the like on both surfaces of the Peltier element 1 to form a sandwich structure. The Peltier device 1 which has become the bonding electrode 10 of the substrate 1
Are joined by soldering or metal paste.
Copper is used as the relaxing member 15 because it is a material having high electric conductivity and thermal conductivity and is inexpensive, and the annealed member 15 is annealed and has a higher copper Young's temperature than the Peltier element 1. This is to reduce the modulus to a value that is substantially the same as the Young's modulus of the Peltier device 1.

In this way, when the relaxation member 15 is interposed between the Peltier element 1 and the substrate 2, the substantial height can be increased while keeping the resistance value of the Peltier element 1 small, and 1 and the relaxation member 15 are applied with a thermal stress, the thermal stress applied to the joint between the Peltier element 1 and the relaxation member 15 can be reduced, and the substrate 2 on the heating side and the cooling can be reduced. Since the distance from the substrate 2 on the side can be increased, the loss due to heat radiation can be reduced and the performance can be improved.

Further, each substrate 2 has a plurality of ridges projecting toward the mutually opposing surfaces at the portion between the bonding electrodes 10 and 10 and the portion between the bonding electrode 10 and the lead electrode 11 to absorb thermal stress. The unit 20 is provided. A heat exchange member is fixed to the outer surface side of each of the substrates 2 and 2 by a bolt penetrating the cylindrical support 4. The thermal stress absorbing section 20 is the substrate 2
As shown in FIG. 7, the alumina layer 22 is formed on the surface of the aluminum 21.
In the case where the heat stress absorbing portion 2 is provided, the aluminum layer 22 and the electrodes 10 and 11 are formed by drawing the aluminum thin plate 21 (thickness 0.1 mm, for example) with a die or the like.
It is formed after the formation of 0.

The thermal stress absorbing portion 20 increases the degree of freedom of expansion and contraction due to heat in the direction along the surface of the substrate 2.
The thermal stress itself applied to the joint between the substrate 2 and the Peltier element 1 (relaxation member 15) is reduced. Moreover, a large number of thermal stress absorbers 20 are provided on both of the pair of substrates 2 and 2 so as to pass between the bonding electrodes 10, and thermal expansion and contraction of the substrate 2 are caused by mounting the Peltier device 1 on the substrate 2. In the region, these thermal stress absorbing parts 20 respectively absorb, and the thermal stress applied to each joint between the Peltier element 1 and the substrate 2 is extremely small, which may cause a problem due to the thermal stress. There is no such thing. In addition, the presence of the relaxation member 15 may reduce the stress applied to the Peltier element 1 itself as described above, so that the Peltier element 1 is not damaged by thermal stress.

Further, the thermal stress absorbing portion provided in the portion between the joining electrode 10 and the lead electrode 11 has the same screw tightening torque pressure as that when the heat exchanging member is attached to the substrate 2 by utilizing the supporting column 4. It also reduces the influence on the department. Since the substrate 2 is provided with a portion that is deformed by thermal expansion and thermal contraction in order to reduce the stress applied to the joint portion, as compared with the substrate 2 that has been conventionally used,
Thin sheet is preferably thick, preferably to the improvement of this point thermoelectric performance.

Further, as shown in FIG. 7, a part of the bonding electrode 10 is mounted on the thermal stress absorbing portion 20 formed as a ridge, and the Peltier element 1 is mounted on this mounting portion.
By restricting the position of (and the block of the relaxation member 15) so that the thermal stress absorbing portion 20 also serves as an array positioning member for the Peltier elements 1, variation during assembly is reduced and the Peltier elements 1 are separated from each other. The insulating pitch can be kept constant, which contributes to the improvement of the assemblability and the electrical characteristics. In forming the bonding electrode 10 in this way, an insulating material such as the solder resist 8 may be used. Bonding electrode 10 and lead electrode 11 by the thermal spraying method
Can be easily and accurately formed.
That is, even if powder of copper or the like during thermal spraying adheres to a portion other than the electrode forming portion, it can be easily removed, and insulation between the electrodes can be reliably performed.

FIG. 8 shows another embodiment. Here substrate 2
Between the mounting region of the Peltier device 1 and the joint portion of the seal frame 3 on the outer periphery of the Peltier device 1, a step portion 23 is provided to lower the mounting region. In this case, when a heat exchange member 9 such as a heat exchange fin is fixed to the outer peripheral portion of the mounting area on the outer surface of the substrate 2 by using bolts passing through the support columns 4, the heat exchange member 9 and the substrate 2 are not covered. A minute gap can be formed between the mounting area and the mounting area. The existence of this gap allows the substrate 2 to bend due to thermal expansion and thermal contraction, and accordingly, thermal stress is less likely to act on the joint between the substrate 2 and the Peltier element 1, Problems due to thermal stress can be avoided. Further, forming such a minute gap can almost completely prevent the tightening torque pressure of the bolt from being applied to the mounting area, and is orthogonal to the substrate 2 based on the tightening torque pressure. It is possible to avoid applying a directional stress to the joint between the substrate 2 and the Peltier element 1. The height H of the gap due to the stepped portion 23 is set to 1 μm in order to suppress deterioration of thermal performance.
m to 100 μm is suitable. In addition, the gap is filled with grease or the like to improve the heat transfer characteristic between the substrate 2 and the heat exchange member 9.

As shown in FIG. 9, if a stepped portion 23 is also formed with a bent portion having a U-shaped cross section, the stepped portion 23 absorbs thermal expansion and contraction of the substrate 2 by deformation of the bent portion. Therefore, the amount of bending of the substrate 2 can be suppressed.
Therefore, the thermal stress applied to the joint portion can be further reduced, and even if the height H of the gap is reduced, the mounting region of the Peltier element 1 on the substrate 2 hits the heat exchange member 9 in a curved manner. Therefore, the heat transfer characteristics between the substrate 2 and the heat exchange member 9 can be improved.

The gap may be obtained by forming a minute recess on the heat exchange member 9 side. Further, the thermal stress absorbing portion 20 and the gap may be used together. Further, although the thermal stress absorbing portion 20 formed by the ridge (concave groove) is shown, the thermal stress absorbing portion 20 may be formed by a hole provided in the substrate 2. The thermal stress absorbing portion 20 may be provided not intermittently but intermittently.

[0024]

As described above, in the present invention, since the thermal stress absorbing portion that deforms according to the thermal stress is provided between the Peltier element bonding portions of the Peltier element mounting portion on the substrate, the thermal stress absorbing portion is It reliably absorbs the thermal stress acting between the substrate and the Peltier element, and therefore the reliability of the joint between the Peltier element and the substrate against the thermal stress can be improved.

At this time, when a ridge formed between the Peltier element joints is used as the thermal stress absorber provided on the substrate,
The thermal stress absorption portion can be easily formed. In addition, if the protrusion also serves as an array positioning member for the Peltier element, the assembling property can be improved. Further, the heat exchange member is closely adhered and fixed in the heat exchange member mounting region on the outer periphery of the Peltier device mounting region of the substrate, and a minute gap is provided between the outer surface of the Peltier device mounting region of the substrate and the heat exchange member. Then, since the gap allows the curvature due to the thermal expansion and the thermal contraction of the substrate, the thermal stress applied to the joint portion between the substrate and the Peltier element can be reduced ,
Therefore, the problem due to thermal stress can be practically eliminated, and the reliability of the joint can be improved. In addition, since the stress generated by the force for attaching the heat exchange member acting on the joint between the Peltier element and the substrate can be reduced, the reliability of the joint can be improved also in this respect.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the above.

FIG. 3 is a perspective view of the above.

FIG. 4 is a sectional view of the same.

FIG. 5 is a cutaway front view showing the one substrate of the above.

FIG. 6 is a cutaway front view showing the other substrate of the above.

FIG. 7 is an enlarged sectional view of the above.

FIG. 8 is a sectional view of another example of the above.

FIG. 9 is a sectional view of still another example of the above.

[Explanation of symbols]

1 Peltier element 2 substrates 20 Thermal stress absorber

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Komatsu Lighting, 1048, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Works, Ltd. (72) Hiroaki Okada, 1048, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Works, Ltd. (72) Inventor Hiroyuki Inoue 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) Reference JP 59-167077 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 35/32 F25B 21/02

Claims (4)

(57) [Claims] 1. A Peltier module in which a plurality of Peltier devices are arranged side by side between a pair of substrates, and the Peltier device is joined to a joining electrode provided on each substrate.
The Peltier module, wherein the substrate on which the bonding electrodes are provided is provided with a thermal stress absorbing portion that deforms according to thermal stress between the Peltier element bonding portions of the Peltier device mounting portion. 2. The Peltier module according to claim 1, wherein the thermal stress absorber is a ridge formed between the Peltier element joints. 3. The Peltier module according to claim 2, wherein the protrusion also serves as an array positioning member for the Peltier element. 4. A Peltier module in which a plurality of Peltier elements are arranged side by side between a pair of substrates whose heat exchange members are fixed to their respective outer surfaces, and the Peltier elements are joined to the joining electrodes provided on each substrate. The heat exchange member is closely attached and fixed in the heat exchange member mounting area on the outer periphery of the Peltier element mounting area of the substrate, and a minute gap is provided between the outer surface of the Peltier element mounting area of the substrate and the heat exchange member. Peltier module that is characterized by being.