JPH0864876A - Thermomodule - Google Patents

Abstract

PURPOSE: To prevent the damage to a thermoelectric semiconductor element and to improve the durability by connecting either the heat absorbing side electrode or the heat radiating side of a heat exchange board to the heat exchange board by an adhesive material having excellent heat conductivity and elasticity, and connecting the other electrode to the board by solder. CONSTITUTION: Either the heat absorbing side electrode or the heat radiating side of the heat exchange board of a thermomodule in which one pair or more of thermoelectric semiconductor element pair are disposed via an electrode on the board is connected to the board by an adhesive material having excellent heat conductivity and elasticity, and the other electrode is connected to the board by solder. For example, an electrode B is connected on the metal film C of the upper surface of a ceramic board A by solder D. N-type and P-type thermoelectric semiconductor elements E are connected to the electrode B via solder F. An electrode G is connected to the ceramic board H via an adhesive material having excellent heat conductivity and elasticity. The electrode G is connected to the element E by the solder F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode on either the heat absorbing side or the heat radiating side of a heat exchange substrate, which is joined to the heat exchange substrate by an adhesive material having good thermal conductivity and elasticity. The present invention relates to a thermo module having improved durability.

[0002]

2. Description of the Related Art Thermomodules are mainly used for precision temperature controllers, portable cool boxes, small dehumidifiers, etc. As shown in FIG. 1, in these thermomodules, N-type thermoelectric semiconductor elements 1 and P-type thermoelectric semiconductor elements 2 are alternately arranged, and the upper and lower surfaces of two adjacent thermoelectric semiconductor elements are connected by electrodes 3 made of metal or the like. As a result, the N-type thermoelectric semiconductor element 1 and the P-type thermoelectric semiconductor element 2
Are connected in series, and the electrodes 3 on the upper surface and the lower surface of each thermoelectric semiconductor element are fixed to the heat exchange substrate 4, respectively. When a direct current is applied to both terminals 5 and 5, the heat exchange substrate on one side becomes a heat absorption surface (low temperature) and the heat exchange substrate on the other side becomes a heat dissipation surface (high temperature) due to the Peltier effect. The most commonly used thermomodule has a maximum current of 10 A or less and a size of about 15 to 40 mm square.

Such a thermo module is manufactured by fixing a thermoelectric semiconductor element on an electrode fixed on a heat exchange substrate via a bonding material such as solder. Therefore, when the thermo module is energized, the heat exchange substrate on one side becomes low temperature, and the heat exchange substrate on the other side becomes high temperature, thermal stress is generated due to this temperature difference, and damage occurs near the junction of the thermoelectric semiconductor element,
Eventually, the thermomodule cannot be energized and it will fail. The thermal stress becomes larger especially as it approaches the end of the heat exchange substrate, and the corner becomes the largest. Therefore, a large thermomodule is more likely to generate large thermal stress than a small thermomodule. Considering these points, a plurality of small thermomodules will be used instead of a large thermomodule. However, even if you simply think about it, the case of using one large thermo module and the case of a small thermo module 2
In the case of using the individual pieces, the latter is unavoidable in terms of cost, for example, the inspection cost is doubled, and it is desirable that the number of pieces used is as small as possible.

It is an object of the present invention to provide a thermo module in which damage to a thermoelectric semiconductor element is prevented and durability is improved.

[0005]

This problem is solved by either the heat absorption side or the heat dissipation side of the heat exchange substrate in the thermomodule in which one or more pairs of thermoelectric semiconductor elements are arranged on the heat exchange substrate via electrodes. The one electrode and the heat exchange substrate are joined by an adhesive material having good thermal conductivity and elasticity, and the other electrode and the heat exchange substrate are joined by soldering.

In the present invention as described above, since either the heat absorbing side electrode or the heat radiating side electrode is joined to the heat exchange substrate by an adhesive material having good thermal conductivity and elasticity,
The adhesive material absorbs the thermal stress generated by energizing the thermomodule, and prevents the thermoelectric semiconductor element (particularly the corner) from being cracked.

FIG. 2 shows the structure of the thermo module according to the present invention. A case of producing such a thermo module will be described below in the order of steps. A ceramic substrate A having a metal film C formed on its upper surface is prepared. Then, the electrode B is bonded onto the metal film C of this substrate through the solder D. Then, the N-type and P-type thermoelectric semiconductor elements E are bonded onto the electrodes B via the solder F. A ceramic substrate H is prepared. Then, the electrode G is bonded onto the substrate H via the adhesive material I having good thermal conductivity and elasticity. Further, the electrode G and the thermoelectric semiconductor element E are solder F
To join through.

Here, it is conceivable that the electrodes and the heat exchange substrates on both the heat absorbing side and the heat radiating side are joined using an adhesive material having good thermal conductivity and elasticity. However, in this case, the heat transfer due to the Peltier effect is reduced, so that it is limited to only the one of the electrodes on the heat absorption side or the heat dissipation side of the heat exchange substrate as described above.

As the adhesive material having good thermal conductivity and elasticity used in the present invention, since solder is used for joining the heat exchange substrate on the side opposite to the side where this adhesive material is used, melting of cream solder ( Rubber-based or resin-based materials, or these materials, as long as they have good thermal conductivity and can withstand the melting temperature of the solder so that they do not deteriorate even when subjected to reflow, etc., and can absorb the thermal stress associated with thermal cycles. What added various fillers for thermal conductivity improvement, and also a metal, various compounds, and a mixture may be used. More specifically, silicone rubber, butadiene rubber, acrylic resin and the like can be exemplified.

In the present invention, the metal film formed on the heat exchanging substrate is for facilitating the joining of the heat exchanging substrate, which is usually made of ceramic, and the electrodes by using solder, such as tungsten, molybdenum-manganese, and copper. Etc. a coating is applied.

[0011]

Example 1 Thermoelectric semiconductor element pair 127 heat exchange substrate 40 × 40 mm, plate thickness 0.8 mm,
(Alumina substrate with molybdenum-manganese alloy coating) Liquid Si rubber (SE made by Toray Dow Silicone as an adhesive material with good thermal conductivity and elasticity for the heat exchange substrate on one side.
1815 CV) was applied and the electrodes were joined. This is 100 ~
After heating at about 120 ° C., the Si rubber was cured. A thermomodule was produced from this substrate (with electrodes) and another substrate to which electrodes were joined by solder.

[0012]

Example 2 A thermomodule was produced in the same manner as in Example 1 except that an allyl resin (3381 manufactured by Nippon ThreeBond) was used as an adhesive material having good thermal conductivity and elasticity.

[0013]

Example 3 A thermomodule was manufactured in the same manner as in Example 1 except that liquid Si rubber (1862 made by Shin-Etsu Silicone) was used as an adhesive material having good thermal conductivity and elasticity.

[0014]

[Comparative Example 1] For comparison, a thermo module was produced in which both the heat radiation surface and the heat absorption surface were soldered together.

[0015]

[Comparative Example 2] A thermo module was prepared by using liquid Si rubber (1862 made by Shin-Etsu Silicone), which is an adhesive material having good thermal conductivity and elasticity on both the heat radiating surface and the heat absorbing surface.

These were tested for durability. As a test method of durability, two thermomodules are attached to each other, and a maximum current is applied to each thermomodule so that the mating surface becomes a heat absorbing surface. In this test, it was 4.3 amps. The heat generation side radiated heat so that the temperature became constant. After energizing for 55 seconds in this state, the energizing current was reversed for 6 seconds so that the heat absorbing surface became hot immediately, and this was set as one cycle. Thereafter, this cycle was repeated to test the durability. If damage occurs in the vicinity of the junction of the thermoelectric semiconductor element of the thermomodule due to thermal stress, the resistance value of the thermomodule increases, so if this value is examined, the degree of failure will be known. Here, the period was taken until the resistance value became 1.1 times the initial value. The results are shown in Table 1. In Table 1, the values of Comparative Example 1 of solder joining (durability 400 cycles,
The endothermic amount of 19 watts is shown as 1. The maximum current means a current value when the temperature difference between the heat absorbing side and the heat radiating side obtained when the heat absorbing side of the thermomodule is adiabatic is maximized. It is said that the maximum temperature difference of the thermo module generally used is 60 ° C or more. Even if a current exceeding the maximum current is applied to the thermo module, a temperature difference exceeding the maximum temperature difference cannot be obtained. Further, the above-mentioned heat absorption amount is a value obtained by measuring the heat absorption amount on the heat absorption surface when the power is supplied and the wattage, when the heat radiation surface temperature is 30 ° C., the heat absorption surface temperature is 5 ° C., and the temperature difference is 25 ° C.

[0017]

[Table 1]

As shown in Table 1, in the examples, even the material having good thermal conductivity and elasticity, the endothermic property is reduced by up to 9% due to the increase of thermal resistance as compared with the solder, but the durability is 70%.
More than doubled.

[0019]

According to the present invention as described above, the bonding between the heat exchange substrate and the electrode on either the heat absorbing side or the heat radiating side is made of an adhesive material having good thermal conductivity and elasticity. Therefore, the thermal stress generated by energizing the thermomodule is absorbed by this adhesive material, the damage of the thermomodule due to the thermal stress is reduced, and the durability is remarkably improved. Therefore, even in the case of a particularly large thermomodule, the problem that the corners are easily damaged is solved.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a most common thermo module.

FIG. 2 is an explanatory view showing a cross-sectional structure of a thermo module according to the present invention.

[Explanation of symbols]

 1 N-type thermoelectric semiconductor element 2 P-type thermoelectric semiconductor element 3 Electrode 4 Heat exchange substrate 5 Terminal A Ceramic substrate B Electrode C Metal film D Solder E Thermoelectric semiconductor element F Solder G Electrode H Ceramic substrate I High thermal conductivity and elasticity A material

Claims (1)

[Claims] 1. A thermomodule in which one or more pairs of thermoelectric semiconductor elements are arranged on a heat exchange substrate via electrodes, wherein the heat exchange substrate has either one of the heat absorption side or the heat radiation side and the heat exchange substrate. The thermomodule, characterized in that the bonding is performed with an adhesive material having good thermal conductivity and elasticity, and the other electrode is bonded to the heat exchange substrate by soldering.