JP3520607B2 - Peltier module and manufacturing method thereof - 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 and a method for manufacturing the same.

[0002]

2. Description of the Related Art A Peltier device, which is a thermoelectric conversion device, is usually constructed as a Peltier module in which a plurality of Peltier devices are electrically connected in series and thermally arranged in parallel. 35-182
As disclosed in Japanese Patent No. 59, Japanese Patent Application Laid-Open No. 6-147329, etc., a structure in which P-type and N-type elements are connected in a π-type by a junction electrode is arranged.

By the way, in the case of electronic cooling or heating, thermal stress is generated in the joint surface between the element and the joint electrode in the direction parallel to the joint surface. In the above-mentioned conventional example, the Peltier element is directly connected to the joint electrode. Since soldering is performed, stress is often applied to the element due to the above-mentioned thermal stress, which often causes fatigue failure of the joint surface or failure of the element itself.

For this reason, the paper “FABLICATION OFSELENIDE” published in ICT3 in 1980.
SEGMENTED ELEMENTS N.M. B. E
lsner, J .; Chin, and G.C. H. Re
Yynolds ”and Japanese Patent Application Laid-Open No. 6-310765 disclose that a thermal stress is relaxed by interposing a relaxation member made of a copper alloy or copper between the element and the substrate.

[0005]

However, even in the structure as described above, destruction which seems to be caused by thermal stress occurs, and further countermeasures against thermal stress are required. Further, in manufacturing the Peltier module in which the relaxation member is interposed between the element and the substrate, since the relaxation member is individually bonded to the chips of each Peltier element, the labor required for the manufacturing is very large. The cost is high.

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 having high resistance to thermal stress and good thermal performance. Another object of the present invention is to provide a method of manufacturing a Peltier module that can manufacture the Peltier module at low cost.

[0007]

SUMMARY OF THE INVENTION The present invention, however, provides a Peltier module in which a plurality of Peltier elements are arranged side by side between a pair of substrates. The main feature is that the Peltier device is bonded to the substrate via a relaxation member for relaxing thermal stress having Young's modulus that is substantially equal.

As the relaxing member here, annealed copper can be preferably used. Further, it is preferable to set a soldering temperature for joining the Peltier element and the relaxing member higher than a soldering temperature for joining the relaxing member and the substrate. It is also preferable that at least one of the bonding between the substrate and the substrate is made of a noble metal conductive paste.

According to the present invention, relaxation members for thermal stress relaxation having high thermal conductivity and electric conductivity and having Young's modulus substantially equal to Young's modulus of the Peltier device are laminated and bonded to both surfaces of the Peltier device in a wafer state. Then, the obtained laminated body is cut to form a Peltier element chip in which a relaxation member is bonded to both surfaces, and the Peltier element chip is arranged side by side between a pair of substrates and a relaxation member for the Peltier device chip and the relaxation member. It has another feature in joining.

[0010]

According to the present invention, since the relaxation member having Young's modulus substantially equal to that of the Peltier element is interposed between the substrate and the Peltier element, thermal stress is applied to the integral member of the Peltier element and the relaxation member. Therefore, the thermal stress applied to the joint between the Peltier element and the relaxation member can be reduced.

At this time, if annealed copper is used as the relaxing member, the relaxing member having the required performance can be obtained at low cost. If the soldering temperature for joining the Peltier element and the relaxing member is set higher than the soldering temperature for joining the relaxing member and the substrate, the former soldering part will be It will not be remelted and the reliability will not be reduced. Even if at least one of the joining between the Peltier element and the relaxing member and the joining between the relaxing member and the substrate is made of the noble metal conductive paste, the noble metal conductive paste is not remelted, so that deterioration in reliability can be prevented.

Then, a relaxation member for thermal stress relaxation having a high thermal conductivity and an electrical conductivity and having a Young's modulus substantially equal to that of the Peltier device is laminated and bonded to both surfaces of the Peltier device in a wafer state. The laminated body is cut to form a Peltier element chip in which relaxation members are bonded to both surfaces, and the Peltier element chips are arranged side by side between a pair of substrates to bond the substrate and the relaxation member of the Peltier device chip. Since it is manufactured in this way, it is possible to easily and in large quantities obtain a Peltier element in which the relaxing member is bonded to both surfaces.

[0013]

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 bonding 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 an electric insulation property is a simple substance such as alumina or aluminum nitride, or a surface of aluminum whose surface is alumite treated, and a surface of aluminum having a layer of alumina or silicon oxide. Is a sheet-like member formed of a composite material such as a copper foil, a thin adhesive insulating layer formed on the surface of copper, and the bonding electrode 10, the lead electrode 11, the terminal portion 12, etc. It is formed by the thermal spraying method. Further, each substrate 2 is provided with a plurality of ridges 20 projecting toward the facing surface side of each other in a portion between the bonding electrodes 10 and 10 and a portion between the bonding electrode 10 and the lead electrode 11. Each board 2,
A heat exchange member is fixed to the outer surface side of 2 by a bolt that penetrates the cylindrical support 4.

When the substrate 2 has an aluminum layer provided on the surface of aluminum, the ridges 20 are formed by drawing a thin plate of aluminum (for example, a thickness of 0.1 mm) with a die or the like. The layers and electrodes 10, 11 are formed after the ridges 20 are formed. The ridges 20 are provided to reduce the thermal stress on the Peltier device 1 generated in the direction parallel to the substrate 2 by increasing the degree of freedom of expansion and contraction in the direction along the surface of the substrate 2. .

The seal frame 3 is for sealing the portion where the Peltier element 1 is arranged, and is formed of an insulating material such as ABS resin or non-hydrophilic treated paper in a tubular shape. 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 made 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 here 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, and both surfaces of the Peltier element 1 are preliminarily plated with a harmless metal, nickel, The Peltier element 1 is sandwiched between the pair of relaxation members 15 and 15 by soldering the relaxation member 15 plated with gold, solder or the like to both surfaces of the Peltier element 1, and the Peltier element 1 having the sandwich structure is formed. Is bonded to the bonding electrode 10 of the substrate 1 by solder bonding or metal paste.

In addition, when the Peltier device 1 is not directly bonded to the bonding electrode 10 but the relaxing member 15 is interposed, it is effective in relaxing the thermal stress. That is, assuming that the width of the Peltier element 1 is L, the height of the Peltier element 1 is 2H, the load applied in the direction parallel to the bonding electrode 10 is 2P, and the strain in the parallel direction due to this load is δ, the strain δ is δ = PH ³ · {1 + 0.71 (L / H) ² −0.1 (L / H) ³ } / 3EI E: Young's modulus, I: Moment of inertia of area, and if strain δ is constant, load P The height H can be increased to reduce the
If the height of the Peltier element 1 itself is increased, the resistance value of the element itself increases and the performance is degraded. Therefore, by arranging the relaxation members 15 and 15 at both ends of the Peltier element 1, the resistance value of the Peltier element 1 is reduced. The height is increased while keeping it small. Further, when the height is increased in this way, the distance between the substrate 2 on the heating side and the substrate 2 on the cooling side can be increased, so that the loss due to heat radiation is reduced and the performance is improved. It will also be possible.

As the relaxing member 15, annealed copper can be preferably used. Copper is generally used as a material having high electrical conductivity and thermal conductivity, but if this copper is used as it is, it causes the problems described above. Is to reduce the Peltier element 1 Young's modulus to almost the same value. In any case, when annealed copper is used as the relaxation member 15, not only is it cost effective, but it is also extremely effective in improving the resistance to thermal stress.

By the way, the Peltier element 1 and the relaxation member 15
When the solder is used for the joining with and the solder is also used for the joining between the relaxing member 15 and the joining electrode 10, the soldering temperature of the latter is set lower than the soldering temperature of the former. When the relaxation member 15 bonded to the Peltier element 1 is bonded to the bonding electrode 10 of the substrate 2, the Peltier element 1 and the relaxation member 1
Therefore, it is necessary to prevent the solder at the joint portion with No. 5 from being remelted and the reliability from being deteriorated. Considering a temperature profile at a level that does not affect the performance of the Peltier device 1, soldering with a peak temperature of 300 ° C. or less is performed for the former and soldering with a peak temperature of 230 ° C. or less for the latter. Good to do.

At least one of the joining portion between the Peltier element 1 and the relaxing member 15 and the joining portion between the relaxing member 15 and the joining electrode 10 may be joined together using a noble metal conductive paste that does not melt even when heat is applied. . When the noble metal conductive paste is used for joining the Peltier element 1 and the relaxing member 15, the plating process for the Peltier element 1 is not necessary. Also,
When at least the noble metal conductive paste is used for joining the Peltier element 1 and the relaxing member 15, the joining and assembling can be performed without concern about the curing temperature. In addition,
By soldering the Peltier element 1 and the relaxing member 15 together,
When the relaxing member 15 and the bonding electrode 10 are bonded with the noble metal conductive paste and the latter bonding is performed later, the curing temperature of the noble metal conductive paste must be lower than the solder melting temperature.

The Peltier device 1 includes a crystal type and a sintered type, but the crystal type is high in efficiency. Therefore, if high efficiency is required, the crystal type is used, but this crystal type has a problem that it is fragile against mechanical stress. On the other hand, the sintered type is less efficient but more resistant to mechanical stress than the crystalline type. For this reason, of the Peltier elements 1 arranged in large numbers, the Peltier elements 1 (P-type elements) located at the four corners and the central portion
If the Peltier element 1 is made of a sintered type and the remaining Peltier element 1 is made of a crystalline type, a mechanical load can be received by the Peltier element 1 of the sintered type, and the load resistance is high and the efficiency is high. Can be obtained. In some cases, it is possible to withstand the load even without the columns 4, which also contributes to downsizing of the module.

In this respect, as shown in FIG. 7, if the height X of the sintering type Peltier element 1 is made larger than the height Y of the crystal type Peltier element 1 by several μm to several hundreds of μm, the crystal type Peltier device 1 of the crystal type is produced. It is possible to more reliably prevent damage to the Peltier device 1. The height difference (X−Y) is filled with solder for joining with the joining electrode 10. Next, a method of manufacturing the Peltier module will be described. As is clear from the above description, in this Peltier module, the sandwich structure having the relaxation members 15 and 15 bonded to both surfaces of the Peltier element 1 is bonded to the substrates 2 and 2. 8 is not manufactured individually, but as shown in FIG. 8, both surfaces of the Peltier device 1 in a wafer state before dicing are preliminarily plated with a harmless metal and plated with nickel, gold, solder or the like. The thin plate-shaped relaxation members 15, 15 that have been applied are joined by solder or the like to form the material W, and then the material W is formed as shown in FIG.
By dicing, the chip having the above sandwich structure is obtained. Therefore, in the chip having the sandwich structure, the cross-sectional area of the relaxation member 15 and the cross-sectional area of the Peltier element 1 are substantially equal to each other, which is due to the thermal integration of the Peltier element 1 and the relaxation member 15. It is also preferable in terms of conversion.

Relaxing member 15 for each chip of Peltier element 1
Since the bonding is performed in a wafer state instead of bonding, the bonding work itself can be simplified and the amount of bonding work can be greatly reduced, which reduces the manufacturing cost. In addition to having a great effect, the stability and reliability of the joint between the Peltier element 1 and the relaxation member 15 are also improved.

[0028]

As described above, in the present invention, the Peltier element is provided on the substrate via the relaxation member for relaxing thermal stress having high thermal conductivity and electrical conductivity and having Young's modulus substantially equal to that of the Peltier element. Since it is joined to the Peltier element and the relaxation member, thermal stress is applied to the integral member, and the thermal stress applied to the joint between the Peltier element and the relaxation member can be reduced. It is possible to prevent damage to the Peltier element due to thermal stress, and it is possible to use a Peltier element having high thermoelectric performance as the Peltier element.

When annealed copper is used as the relaxation member, the relaxation member having the required performance can be obtained at low cost, and the soldering temperature for joining the Peltier element and the relaxation member can be relaxed. If the temperature is set higher than the soldering temperature for joining the member and the board, the former soldered part will not be remelted during the latter soldering, and therefore the remelting The reliability is not deteriorated. Even if at least one of the joining between the Peltier element and the relaxing member and the joining between the relaxing member and the substrate is made of the noble metal conductive paste, the noble metal conductive paste does not re-melt, so that it is possible to prevent deterioration of reliability. The one with high reliability can be obtained.

Then, on both surfaces of the Peltier element in a wafer state, relaxation members for thermal stress relaxation having high thermal conductivity and electrical conductivity and having Young's modulus substantially equal to Young's modulus of the Peltier element are laminated and bonded, respectively, and obtained. The laminated body is cut to form a Peltier element chip in which relaxation members are bonded to both surfaces, and the Peltier element chips are arranged side by side between a pair of substrates to bond the substrate and the relaxation member of the Peltier device chip. Since it is manufactured by that, that is, the relaxing member is not joined for each chip of the Peltier element but is joined in the wafer state, the joining work itself is simple and the amount of joining work is increased. Therefore, it has a great effect on the reduction of the manufacturing cost and also improves the stability and reliability of the joint between the Peltier element and the relaxation member. Also those having a significant effect.

[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 explanatory diagram of another example of the above.

8A and 8B are explanatory views of the manufacturing process of the above, wherein FIG. 8A is a schematic sectional view and FIG. 8B is a schematic plan view showing a cut line.

[Explanation of symbols]

1 Peltier element 2 substrates 15 Relaxation member

─────────────────────────────────────────────────── ─── 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, Osaka Prefecture Matsushita Electric Works, Ltd. (56) Reference JP-A-6-310765 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 35/32 F25B 21/02

Claims (5)

(57) [Claims] 1. A Peltier module having a plurality of Peltier elements arranged side by side between a pair of substrates, the thermal stress having a high thermal conductivity and a high electrical conductivity and having a Young's modulus substantially equal to the Young's modulus of the Peltier device. A Peltier module in which a Peltier element is bonded to a substrate via a relaxation member for relaxation. 2. The Peltier module according to claim 1, wherein the relaxation member is made of annealed copper. 3. The soldering temperature for joining the Peltier element and the relaxing member is set higher than the soldering temperature for joining the relaxing member and the substrate.
Peltier module as described. 4. The Peltier module according to claim 1, wherein at least one of the joining between the Peltier element and the relaxing member and the joining between the relaxing member and the substrate is made of a noble metal conductive paste. 5. A relaxation member for thermal stress relaxation, which has a high thermal conductivity and an electrical conductivity and a Young's modulus substantially equal to the Young's modulus of the Peltier device, is laminated and bonded to both surfaces of the Peltier device in a wafer state. The laminated body is cut to form a Peltier element chip in which relaxation members are bonded to both surfaces, and the Peltier element chips are arranged side by side between a pair of substrates to bond the substrate and the relaxation member of the Peltier device chip. Peltier module manufacturing method characterized by