JP2558505B2 - Multi-stage electronic cooler - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cascade-type multistage electronic cooler in which thermoelectric element pairs having a Peltier effect are cascaded in a stepwise manner via a substrate. .

[Prior Art] The multi-stage electronic cooler has, for example, six stages as shown in FIG. 4, and each stage has a thermoelectric element pair A having an N-type semiconductor 1 and a P-type semiconductor 2 as a pair. The electrodes 4 are alternately and serially connected in series by the electrodes 4 joined to the substrate 3. By energizing the thermoelectric element pair A of each stage, the upper substrate side of each stage absorbs heat, and the uppermost substrate 3a is designed to be cooled at the maximum reached temperature. The multi-stage electronic cooler is in the shape of a pyramid, and the ratio of the number of thermoelectric element pairs A in each stage is such that the number gradually increases toward the lower stage.

[Problems to be Solved by the Invention]

The cooling principle of the multi-stage electronic cooler is that the head of each stage absorbs Peltier heat and the bottom produces Peltier heat. Since a constant heat absorption capacity and a constant cooling temperature are obtained, it is important to efficiently transfer the heat of the upper stage to the lower stage.

The insulating ceramics used for the substrate 3 of the multi-stage electronic cooler are usually made of aluminum oxide (Al ₂ O ₃ ) because of the basic requirements of electrical insulation and good thermal conductivity, price, strength and the like. As shown in Fig. 3, this is used, but it has a poor thermal conductivity of about 20w / m · k at room temperature, so the thermal loss in the substrate is large and the maximum cooling temperature of the cooler can be lowered. It was one of the causes.

On the other hand, beryllium oxide (BeO) is used as an insulating ceramic with good thermal conductivity and is actually used.
As shown in Fig. 3, the thermal conductivity is 10 times higher than that of aluminum oxide, but it is highly toxic enough to directly affect human life, and its strength is weak, about 2/3 that of aluminum oxide. Due to its high price, it was used only in special cases.

From this, it is possible to maintain sufficient bending strength,
Further, it is known that the above substrate is made of aluminum nitride due to its lack of identity.

However, as shown in FIG. 4, the conventional multi-stage electronic cooler has a configuration in which the thermoelectric element pair A in the upper stage is arranged substantially at the center of the upper side surface of the substrate 3 in each stage. This means that heat is locally generated at the lower heat absorbing surface to be taken over, and a temperature distribution is generated on the upper substrate 3 of each step due to thermal diffusion in each surface, and heat is efficiently transferred. Didn't.

In order to reduce the temperature distribution in the plane of the upper substrate of each stage, the thickness of the ceramics forming the substrate 3 may be increased.
As a result, the temperature difference between the two sides of the substrate 3 in the thickness direction becomes significantly large, and conversely the efficiency of heat transfer decreases.

It is also conceivable to make the size of the substrate 3 of each stage the same and to arrange the thermoelectric element pairs of each stage evenly, but the arrangement of the elements becomes sparser toward the upper stage, and the arrangement of these elements is Not only does the temperature difference in the plane not improve as much as it becomes sparse, but the area of the uppermost substrate increases, so the light-receiving area increases and the heat load due to radiant heat from the outside increases. The performance of the cooler deteriorates.

The present invention has been conceived in view of the above, in which heat diffusion in the plane of the substrate is good, the temperature distribution of this is minimized, heat transfer from the upper stage to the lower stage is efficiently performed, and the maximum cooling temperature is increased. It is an object to provide a multi-stage electronic cooler that can be lowered.

[Means for solving the problem]

In order to achieve the above object, a metal plate for improving the heat diffusion in the plane of the substrate is provided on the surface of each step of the substrate, and in the blank part where nothing is attached other than the part that becomes the electrode of the thermoelectric element pair. It has an attached structure.

[Work]

On the surface of each substrate, the heat diffusion in the plane of the substrate other than the portion of the thermoelectric element pair where the electrodes are attached is improved, and the temperature distribution of this portion is reduced.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

Example 1 (FIG. 1) Using a six-stage multi-stage electronic cooler shown in FIG. P of A
Type and N type semiconductor devices 1 and 2 were manufactured by using Bi-Te based ones. Then, at this time, a desired circuit pattern is formed on both surfaces of the substrate 3 by photolithography at the positions to be the electrodes of each thermoelectric element pair A, and at the same time, on the upper side surface of the substrate 3 except for the portions to be the electrodes. Make another pattern in the blank part, and attach a copper plate (thickness 300 μm) formed in the shape of each pattern using Bi-Sn eutectic solder to each of the above patterns, and attach the electrode 4 and nothing to the circuit pattern. A metal plate 5 was provided in the blank portion (Fig. 1). Then, the semiconductor elements 1 and 2 of the thermoelectric element pair A were soldered to the electrode 4 to manufacture the above-described 6-stage multi-stage electronic cooler.

When the multi-stage electronic cooler with the above configuration was placed in a vacuum chamber of 10 ^-6 torr, placed on a heat sink kept at 27 ° C, and a current of 3 A was passed, the temperature of the uppermost stage became -90 ° C.

Example-2 (Fig. 2) As in the case of Example-1 above, metallized substrate materials were used on the front and back sides, and on the front and back sides thereof, the parts (circuit patterns) necessary for the electric circuit configuration were formed. Only the electrode 4'made of a copper plate having a thickness of 300 .mu.m is attached by the same method as in the case of Example-1, and the metallization layer 6 is left as it is on the other portion, that is, the blank portion where nothing is attached. After that, the semiconductors 1 and 2 of the thermoelectric element pair A were soldered to the electrode 4 ', and the 6-stage multi-stage electronic cooler shown in FIG. 4 was manufactured.

When the performance measurement of the multi-stage electronic cooler having the above-mentioned configuration was conducted in the same manner as in the case of the above-mentioned Example-1, the temperature of the uppermost stage was −
It reached 88.5 ° C.

Comparative Example A six-stage multi-stage electronic cooler was produced in the same manner as in Examples 1 and 2, using an aluminum oxide DBC substrate manufactured by Nippon Carbide Co. and a P-type and N-type Bi-Te thermoelectric element pair A.

When this multistage electronic cooler was measured in the same manner as in Examples 1 and 2, the temperature of the uppermost stage was -85 ° C.

In both of the above-mentioned Examples, Example-2 is metallized on both sides of the substrate 3'and on the surface of the blank portion other than the electrode 4'on which nothing is attached, so that the material of the substrate 3'is nitrided. By using aluminum ceramics, the temperature at the uppermost stage could be lowered by 3.5 ° C compared to the comparative example.

Further, in Example-1, since the metal plate 5 made of a copper plate was attached to the upper surface of the substrate 3 and the surface of the blank portion where nothing other than the electrodes 4 adhered, a temperature of 1.5 ° C. was higher than that of Example-2. It was low, and it was possible to lower it by 5 ° C. as compared with that of the comparative example.

〔The invention's effect〕

According to the present invention, the heat diffusion in the plane of the substrates 3 and 3'is good,
The temperature distribution of this is minimized, heat is efficiently transferred from the upper stage to the lower stage, and the maximum cooling temperature can be lowered.

[Brief description of drawings]

1 and 2 are perspective views showing a substrate in an embodiment of the present invention, FIG. 3 is a diagram showing thermal conductivity of each material, and FIG. 4 is a perspective view showing an example of a multi-stage electronic cooler. . A is a thermoelectric element pair, 1 and 2 are semiconductor elements, 3 and 3'are substrates, 4 and
4'is an electrode and 5 is a metal plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Yamaguchi 1200 Manda, Hiratsuka, Kanagawa Komatsu Ltd. Research Laboratory (56) Bibliography Sho 61-110838 (JP, U) Sho 63-64048 (JP) , U)

Claims (1)

(57) [Claims] 1. A cascade-type multistage electronic cooler in which thermoelectric element pairs A having a Peltier effect are cascaded in a stepwise manner via substrates 3 and 3'made of insulating ceramics. Aluminum nitride is used for 3 ',
On the surface of the substrate 3, 3'of each step, and the electrode 4, of the thermoelectric element pair A,
In the blank part where nothing is attached except the part where 4'is attached,
A multi-stage electronic cooler characterized in that a metal plate 5 is attached to improve heat diffusion in the plane of the substrates 3 and 3 '.