JPH0342704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermoelectric device, and particularly to its mounting structure.

[Prior art and its problems]

For example, a U-shaped thermoelectric power generator is formed by bonding a P-type semiconductor and an N-type semiconductor, each made of iron silicide (FeSi ₂ ) doped with appropriate impurities such as manganese (Mn) or cobalt (Co), at one end. Elements can easily generate an electromotive force just by applying a temperature difference, exhibit excellent heat resistance and oxidation resistance, and can maintain safe characteristics, so today there is a growing demand for more efficient use of thermal energy. This is a device that is expected to be put into practical use.

In such a thermoelectric power generation element, the electromotive force is determined by the temperature difference Δt between the PN junction on the high temperature side and the anode side and cathode side ends on the low temperature side. Therefore, in order to efficiently acquire electrical energy, it is important to improve the heat dissipation of the open ends (opposite the bonding side) of the anode and cathode sides, which are the low temperature sides.

Therefore, the present inventors coated the low-temperature side end of the thermoelectric power generation element with a conductive film, and formed two ends so that the low-temperature side end came into contact with one end and the other end served as an external connection terminal. The low-temperature side end of the thermoelectric power generation element is placed on a heat sink having a wiring pattern, which is sandwiched and crimped between the top plate and the bottom plate of the heat sink case, and then heated as a whole;
An assembly method is proposed in which the conductive film and the wiring pattern are fused together. (Special application
60-241187) According to this method, the heat sink, which has the low-temperature side end of the thermoelectric generating element fixed on the pattern, is sandwiched between the top plate and the bottom plate of the heat dissipation case in a constantly pressed state, and the element The electrical contact between the device and the external connection terminal (electrode wiring pattern) and the thermal contact between the element and the heat dissipation case are improved.

However, since thermoelectric power generation elements are subject to severe temperature changes, thermal stress may cause cracks in the elements or breakage of the elements.

For example, as shown in Fig. 2, one of the low-temperature side terminals LE of a U-shaped thermoelectric power generation element is fixed, and the high-temperature side end HE is heated by the flame of a gas burner, etc. with the other left free. Let's consider a case.

First, when it is ignited (SP) and the temperature begins to rise,
At first, the temperature of the outer portion of the U-shape increases rapidly and expands, causing the free low-temperature side terminal LE1 to move inward (in one direction) as shown in FIG. (In Fig. 3, time is plotted on the horizontal axis.) Then, as the entire high-temperature side end HE is gradually heated, the low-temperature side terminal LE gradually opens.
The free side is moved outward (in the + direction).

Also, if the gas burner is suddenly turned off (point FP),
As the outside of the high temperature side end is first rapidly cooled, the free low temperature side terminal LE1 temporarily moves outward, and as the whole is further cooled, it gradually returns to its original position.

On the other hand, if both of the low-temperature side elements are fixed as described above, thermal stress due to temperature changes is applied to the elements, so it is thought that the elements are likely to be destroyed. Furthermore, even if the element itself did not break, stress was applied to the heat sink, causing cracks.

The present invention was made in view of the above circumstances, and
The purpose is to provide thermoelectric devices with high reliability and long life.

[Means for solving problems]

Therefore, in the present invention, one of the low-temperature side terminals of the thermoelectric element is fixed on the heat sink, while the other one is not fixed on the heat sink and can be freely shifted, thereby establishing electrical connection. I try to do it separately.

[Effect]

According to this configuration, only one of the low-temperature side terminals of the thermoelectric element is bonded and fixed on the heat sink, and the other one is only placed on the heat sink without being fixed. Therefore, thermal stress is not applied to the element or heat sink, improving durability.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a thermoelectric power generation device according to an embodiment of the present invention.

In this thermoelectric power generation device, low temperature side terminals 1a and 1b of a U-shaped thermoelectric power generation element 1 made of iron silicide are connected to a first terminal disposed on a heat sink 2 made of an alumina ceramic substrate.
The low-temperature side terminal 1b is placed on at least 3b of the second electrode wiring patterns 3a and 3b, and the low-temperature side terminal 1b of the two low-temperature side terminals of this thermoelectric generation element 1 is placed on at least 3b. A zinc-based solder alloy layer 4 is formed on the upper surface of the first terminal 1a, and one end of a first lead wire 5a for taking out the output is buried therein. The first lead wire is slightly loosened so that the middle portion thereof is buried in the solder alloy layer 6 formed on the first wiring pattern 3a, and the other end is connected to the outside.

On the other hand, the lower surface of the second terminal 1b of the low-temperature side terminals is connected to the second electrode wiring pattern 3 on the heat sink 2.
b through a zinc-based solder alloy layer 4.

Furthermore, a second lead wire 5b is formed in the solder alloy layer 6 formed on the second electrode wiring pattern 3b.
is buried.

Here, the zinc-based solder alloy layer used to connect the low temperature side terminals 1a, 1b with the first lead wire 5a and the second electrode wiring pattern 3b has a melting point of approximately
It is a high melting point solder designed to have a temperature of 400°C or higher, and if boric acid or fluorine based flux is used during bonding, it will melt on the oxide film formed on the surface of the low temperature side terminals 1a and 1b. Good electrical and mechanical connections are also achieved with direct solder joints.

In addition, thermoelectric power generation elements are made by directly powder molding and bonding a P-type semiconductor made of iron silicide (FeSi ₂ ) doped with manganese (Mn) and an N-type semiconductor made of iron silicide doped with cobalt (Co). It is a U-shaped element in which one end forms a PN junction and constitutes a high temperature side end, and the other end constitutes two low temperature side terminals of P type and N type.

The following method is used for manufacturing.

First, the first lead wire 5a is placed on the upper surface of one of the low-temperature side terminals 1a of the thermoelectric power generating element, and is fixed with the zinc-based solder alloy layer 4.

Next, the first and second electrode wiring patterns 3
A heat sink 2 having electrodes a and 3b formed thereon is prepared, and a zinc-based solder alloy layer 4 is placed on the second electrode pattern 3b.
The other low-temperature side terminal 1b is fixed through the terminal 1b.

Finally, the middle part of the first lead wire 5a is soldered onto the first electrode wiring pattern 3a with some clearance, and one end of the second lead wire 5b is connected to the second electrode. Wiring pattern 3
Solder joint on b.

In the thermoelectric power generation device formed in this way,
One of the low-temperature side terminals 1a of the thermoelectric generation element is placed freely on the heat sink without being fixed, and only the other terminal 1b has good contact with the electrode wiring pattern on the heat sink. Because it is bonded and fixed to the metal, it does not crack or break even under thermal stress, making it highly reliable.

In addition, since zinc-based high melting point solder is used to bond the low-temperature side terminals of the thermoelectric power generation element, it can withstand high temperatures and maintain sufficient bonding strength.

Although lead wires were used for the electrical connection of the free terminals of the low-temperature side terminals of the thermoelectric power generation element, heat dissipation would be improved if flexible conductive thin plates were used. Thermoelectric efficiency is increased.

Further, this thermoelectric power generation device may be used as is, or the low temperature side may be covered with a suitable case.

Further, in the embodiment, the case where one thermoelectric generation element is used has been described, but it goes without saying that the present invention can also be applied to a case where a plurality of thermoelectric generation elements are disposed on the same heat sink. For example, two thermoelectric power generation elements may be arranged in a horizontal line, adjacent terminals may be connected by lead wires, and the terminals at both ends may be bonded and fixed onto the electrode wiring pattern on the heat sink. It is also applicable to a structure in which a plurality of thermoelectric power generation elements are stacked.

〔Effect of the invention〕

As described above, according to the thermoelectric device of the present invention, the low temperature side terminal of the U-shaped thermoelectric element is placed on the heat sink, and one of the terminals is connected to the electrode wiring formed on the heat sink. While the terminal is bonded and fixed on the pattern, the other terminal is not fixed and electrical connection is made, so even if it is repeatedly heated and thermal deformation occurs, stress will not be generated due to it, and the crack will not occur. Good characteristics can be maintained without causing damage or destruction.

[Brief explanation of drawings]

Figure 1 is a diagram showing a thermoelectric power generation device according to an embodiment of the present invention, Figure 2 is an explanatory diagram of a normal thermoelectric element, and Figure 3 is a diagram showing the low temperature when a temperature change is applied to the thermoelectric element in Figure 2. It is a figure which shows the position (movement) of a side terminal. 1... Thermoelectric power generating element, 1a, 1b... Low temperature side terminal, 2... Heat sink, 3a... First electrode wiring pattern, 3b... Second electrode wiring pattern, 4...
Solder alloy layer (high melting point solder), 5a...first lead wire, 5b...second lead wire, 6...solder alloy layer, HE...high temperature side end, LE...low temperature side terminal,
SP...ignition point, FP...extinguishing point.

Claims (1)

[Claims] 1. A P-type semiconductor and an N-type semiconductor at one end thereof.
Two terminals of a thermoelectric element, which are bonded to form a PN junction, are placed on a heat sink provided with an electrode wiring pattern, and one terminal of the two terminals is bonded onto the electrode wiring pattern. 1. A thermoelectric device characterized in that one terminal is fixed and the other terminal is electrically connected to an external lead via a flexible electrode wiring material. 2. The thermoelectric device according to claim 1, wherein at least an end portion of the electrode wiring material is fixed on a heat sink.