JPH05275754A - Thermomodule - Google Patents

Abstract

PURPOSE:To prevent a damage in an angle part of a thermoelectric semiconductor element and improve durability by a method wherein a pair or more of thermoelectric semiconductor elements are arranged through an electrode on a heat exchange substrate and thermosetting resin is used as a connection material between the heat exchange substrate and the electrode in the electrodes of the angle part of the heat exchange substrate and solder is used as the connection material in the remaining electrodes. CONSTITUTION:On a metallic film K of a ceramic substrate A on the upper surface of which the metallic film K is formed, an electrode B is connected with a terminal C through solder D. N type and P type thermoelectric semiconductor elements E are connected through solder F on the electrode B and the terminal C, and the thermo-electric semiconductor element E is connected with an electrode G through the solder F in the same manner. The lower surface of the electrode G is connected with a ceramic substrate H formed with the metallic film K through solder I. At this time, an electrode in an angle part of the ceramic substrate H is connected with the ceramic substrate H with thermosetting resin J. Thus, a thermal stress caused by making contact with a thermomodule is absorbed by thermosetting resin J of the angle part, whereby a damage can be reduced and durability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermomodule in which the corner electrodes of a heat exchange substrate have improved durability by joining the heat exchange substrate and the electrodes with a thermosetting resin.

[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 surface and / or the lower surface of two adjacent thermoelectric semiconductor elements are provided with electrodes 3 made of metal or the like. By connecting the N-type thermoelectric semiconductor element 1 and the P-type thermoelectric semiconductor element 2 in series, 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 thermo module has a maximum current of 10A or less,
The size is about 15 to 40 mm square.

Such a thermomodule 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 thermomodule 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 occurs due to this temperature difference, and damage occurs near the junction of the thermoelectric semiconductor element,
Eventually, the thermomodule cannot be energized, resulting in failure. 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. In consideration of 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 at the corners of a thermoelectric semiconductor element is prevented and durability is improved.

[0005]

[Problems to be Solved by the Invention] Such a problem is that the electrodes at the corners of the heat exchange substrate in the thermomodule in which one or more pairs of thermoelectric semiconductor elements are arranged via electrodes on the heat exchange substrate are heat exchanged. This is achieved by using a thermosetting resin as the bonding material between the substrate and the electrodes and using solder as the bonding material for the remaining electrodes.

In the present invention as described above, the thermosetting resin, which is the joining material at the corners, is easily broken by the thermal stress generated by energizing the thermomodule, and the thermal stress is absorbed thereby. The damage in the vicinity of the joint of the thermoelectric semiconductor element is eliminated, and the durability of the thermo module is improved.

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 K formed on its upper surface is prepared. Then, the electrode B and the terminal C are bonded to each other on the metal film of this substrate through the solder D. Then, the N-type and P-type thermoelectric semiconductor elements E are bonded onto the electrodes B and the terminals C via the solder F. , To, the electrode G is bonded to the thermoelectric semiconductor element via the solder F, and the electrode G is bonded to the ceramic substrate H having the metal film formed on the lower surface via the solder I. At this time, the electrodes at the corners of the ceramic substrate H are bonded to the ceramic substrate H with the thermosetting resin J.

Here, it is conceivable that all the joining of the electrode and the heat exchange substrate is performed with a thermosetting resin. However, in this case, the heat transfer due to the Peltier effect is reduced by the thermosetting resin, so that it is desirable to limit to the electrodes at the corners of the heat exchange substrate as described above. As the thermosetting resin used in the present invention, a polyimide resin, an epoxy resin, or the like can be preferably applied, and solder is used as the remaining bonding material according to a conventional method.

[0009]

Example 1 Thermoelectric Semiconductor Element Pair 127 Heat Exchange Substrate 40 × 40 mm, Plate Thickness 0.8 mm Among the joint portions 127 of the heat exchange substrate on one side where a metal film pattern is formed in advance and the electrode, as shown in FIG. , Liquid polyimide (PIX-3400 manufactured by Hitachi Chemical Co., Ltd.) is applied to 32 places (B in FIG. 3) located in a square of the heat exchange substrate, and cream solder is applied to other bonding places (A in FIG. 3),
Assembled After heating this at about 2 to 300 ° C., the polyimide was cured, and further cooled to cure the solder to prepare a thermo module. For comparison, a thermo module in which all of the joints in FIG. 3 were soldered was separately prepared and used as a comparative example. These were tested for durability.

As a method of testing durability, the cooling side is surrounded by a heat insulating material, and a maximum current is applied so that heat does not flow. The heat generation side radiates heat so that the temperature becomes constant. 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 the degree of failure can be known by examining this value. Here, it is a period until the resistance value becomes 1.1 times the initial value. The results are shown in Table 1. Table 1 shows the case where the value of the comparative example is 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 thermo module is adiabatic is maximized. It is said that the maximum temperature difference of a 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.

[0011]

[Table 1]

From Table 1, in the examples, the endothermic property is reduced by about 2% due to the increase in the thermal resistance due to the polyimide, but the durability is improved five times.

The reason why the thermosetting resin is used in the present invention is that the resin can be cured in the same step as the melting (reflow etc.) of the cream solder. However, a thermoplastic resin, a metal, various compounds, or a mixture which is easily damaged by thermal stress may be used.

[0014]

As described above, according to the present invention, since the corner portions are bonded by the thermosetting resin as the bonding material between the heat exchange substrate and the electrodes in the thermo module, heat generated by energizing the thermo module Since the stress is absorbed by the thermosetting resin at the corners, damage to the thermomodule due to thermal stress is reduced, and durability is significantly improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a most general thermo module.

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

FIG. 3 is an explanatory diagram showing a joint portion between a heat exchange substrate and an electrode in the example.

[Explanation of symbols]

 1 N-type thermoelectric semiconductor element 2 P-type thermoelectric semiconductor element 3 Electrode 4 Heat exchange board 5 Terminal

Claims (1)

[Claims] 1. In a thermomodule in which one or more pairs of thermoelectric semiconductor elements are arranged on a heat exchange substrate via electrodes, the electrodes at the corners of the heat exchange substrate are heat-cured with a bonding material between the heat exchange substrate and the electrodes. Thermoplastic module with a conductive resin and solder for the remaining electrodes.