Production of semiconductor refrigeration components

Under the action of an external electric field, the conductive property generated by the "hole" in the full band is called "hole" conductive, and the conductive property generated by the electron in the empty band is called "electron". A semiconductor that relies on hole conduction is a p-type semiconductor, and a semiconductor that relies on electron conduction is an n-type semiconductor.

When one end of the p-type semiconductor is soldered to one end of the n-type semiconductor, as shown in FIG.

Figure 1 Schematic effect diagram

When the current is applied in a certain direction, the solder joint becomes hot, and when the reverse current is passed, the solder joint becomes cold. This phenomenon is called the Peltier effect.

The Peltier effect of semiconductors is commonly used in the industry to make refrigerators. The refrigeration element is composed of a p-type semiconductor and an n-type semiconductor, and is surrounded by a plurality of refrigeration elements into a cooling well, which can be used in refrigerators and air conditioners.

The following is a brief introduction of a cooling element mainly composed of a bismuth telluride single crystal.

First, raw material technical standards

No part of the semiconductor is required to be prepared with pure or high-purity elements. The chemical purity requirements of various elements are: 铋 using No. 1 fine 铋; 碲 using No. 1 fine 碲; selenium using No. 1 refined selenium; 锑 using four nine rectifying 锑Lead is made of high-purity lead.

The fine sorghum is prepared by vacuum distillation of No. 1 hydrazine containing more than 99.85%; the fine sorghum No. 1 is purified by vacuum filtration to be a high-purity glutinous rice.

Second, the process

as shown in picture 2.

Figure 2 Process diagram of semiconductor refrigeration components

Third, the main technical conditions

(1) Ingredients

1, with four tellurium iodide. As an n-type material dopant.

The raw material Te ≥ 99.99%, and the iodine is pure reagent.

The enamel was ground into a powder of about 80 mesh.

Ratio (mass ratio) I: Te = 4:1

The degree of vacuum is not higher than 6.7 Pa.

Synthesis temperature: Slowly raise the temperature to 350 to 380 °C.

Synthesis time: 8 hours, then slowly cooled to room temperature.

Grinding: The synthetic material was ground to 100 mesh in a glass mortar, stored in a ground glass bottle, and placed in a desiccator.

2. Vacuum distillation. The raw material contains more than 99% bismuth.

Distillation temperature: 500 to 520 ° C; condensation temperature: 320 to 350 ° C.

The degree of vacuum is not higher than 6.7 Pa.

Time: 4 to 4.5 hours / furnace.

3. Vacuum distillation. The raw material contains more than 99.85% bismuth.

The distillation temperature is 700 to 720 ° C; the condensation temperature is 500 to 550 ° C.

The degree of vacuum is not higher than 1.3 Pa.

Time: 1 to 5 hours / furnace.

4. Vacuum filtration. The raw material contains not less than 99.99%.

Filtration temperature: 350 to 400 °C.

The degree of vacuum is not higher than 6.7 Pa.

Discharge temperature: room temperature.

5, the ratio of ingredients. As shown in Table 4.

Table 4 Chemical composition of semiconductors (%)

(2) Regional melting. Vertical crystal pulling.

Synthesis temperature: 620 ~ 630 ° C.

The degree of vacuum is not higher than 6.7 Pa.

(three) slice. Feeding speed ≥ 1.5 minutes / piece.

(4) Component 搪铋. Using Bi-Sb alloy (Bi90, Sb10).

The temperature of 350 ° C.

(E) element linked to tin. Temperature 380 ° C.

Solder composition (%) Sn60, Pb40.

(6) Metallization of the tiles. Including line printing, baking, plating, and tin on ceramic.

(7) Assembly. Including component array, welding cover, welded cold plate, power-on inspection.

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