Thermoelectric device and method of fabricating the same

Details Thermoelectric device and method of fabricating the same Thermoelectric device and method of fabricating the same

2000-05-23

2001-12-11

Chaudhuri, Olik (Department: 2814)

Semiconductor device manufacturing: process

Making device or circuit responsive to nonelectrical signal

C438S054000, C438S055000, C136S203000, C136S204000, C136S212000

Reexamination Certificate

active

06329217

ABSTRACT:

TECHNICAL FIELD
This invention relates to a structure of a thermoelectric device and a method of fabricating the thermoelectric device, and more particularly, a structure of a pad for a lead line to connect a thermoelectric device to another circuit, and a method of fabrication thereof.
BACKGROUND TECHNOLOGY
Various metal materials have been used for electric parts, and micronization of the electric parts is being developed every year. A typical example is a thermoelectric device. In the thermoelectric device, a voltage is generated by providing a difference in temperature between the opposite ends thereof. A device designed to extract the voltage as electric energy is a thermoelectric power generator. Such a thermoelectric device wherein heat energy can be converted directly into electric energy has attracted much attention as an effective means of utilizing heat energy, as represented by the case of waste heat utilization.
Meanwhile, the flow of a current caused to occur through the thermoelectric device results in generation of heat at one end thereof, and absorption of heat at the other end thereof. This is due to the Peltier effect, and a cooler can be manufactured by taking advantage of such a phenomenon of heat absorption. This type of cooler which does not comprise mechanical components and can be reduced in size has an application as a portable refrigerator, or a localized cooler for lasers, integrated circuits, and the like.
The thermoelectric device which is applicated the thermoelectric power generator or cooler is simple in construction, and is in a more favorable condition for miniaturization as compared with other types of power generators, and there will not arise a problem of leakage or depletion of electrolyte as with the case of a redox cell. Therefore, the thermoelectric device has promising prospects for application to portable electronic devices such as an electronic wrist watch.
The thermoelectric device is formed with plural thermocouples consisting of p-type and n-type thermoelectric semiconductors, aligned in series.
In the case of the difference in temperature between a cold junction and a hot junction of the thermoelectric device is 1.30° C., in order to obtain voltage of more than 1.5 V which is necessary for driving the wrist watch, more than 2000 pairs of thermocouples are required even with a BiTe-based thermocouples which is said to have a high performance index.
The thermoelectric device is required to be as small in size as possible, because it is disposed in a highly-limited space such as the interior of a wrist watch. Therefore, a highly-dense and minute thermoelectric device in size is required so that many thermocouples can be arranged in a limited area.
For example, Japanese Patent Laid-open No. 63-20880 discloses a method of fabrication of a miniaturized thermoelectric device with plenty of thermocouples in high density.
In this publication, mentioned is a method of fabrication to form a p-type bar-shaped device and an n-type bar-shaped devices in a manner such that the p-type and n-type thermoelectric materials in a thin sheet-like shape are laminated on top of each other in layers while interposing a heat insulating material between respective p-type and n-type thermoelectric material layers, and grooves are formed at fixed intervals in a perpendicular s direction to a laminated surface. The p-type bar-shaped device and the n-type bar-shaped device are connected in series with electrode materials at each end.
The thermoelectric device formed with the above-described method has a size of 30×20×3.5 (mm), containing 3500 pairs of thermocouples, which amounts to 7000 pieces of the total of the bar-shaped devices in an extremely high density.
However, in the case of connecting to another circuit from this thermoelectric device, current must be taken out from one of the electric patterns shown here. When ordinary solder is used to take out the lead line for this purpose, it needs very fine work and a special device. In addition, formation of a large electrode for the lead line requires a large thermoelectric device itself, which is inconvenient to dispose in a limited space.
It is an object of the present invention to solve the above-described disadvantages and to provide a structure of the thermoelectric device which takes out a lead line easily and efficiently while having a fine and high-density structure, and a method of fabrication thereof.
DISCLOSURE OF THE INVENTION
In order to achieve the above described objects, the present invention adopts a structure explained hereinafter in the thermoelectric device and the method of fabrication thereof.
The thermoelectric device of the present invention comprises a thermoelectric device block having two interconnecting end faces on which a plurality of n-type bar-shaped devices consisting of n-type thermoelectric semiconductors and a plurality of p-type thermoelectric devices consisting of p-type thermoelectric semiconductors are regularly disposed through an insulating layer and fixed, and both end faces of each of said n-type bar-shaped devices and p-type bar-shaped devices are exposed, an interconnection conductor connecting each end face of said n-type bar-shaped device and p-type bar-shaped device on said each interconnecting end face of said thermoelectric device block to connect said n-type bar-shaped devices and p-type bar-shaped devices in series, a pair of terminal conductors provided on a surface excluding said interconnecting end face of said thermoelectric device block, and electrically connected each bar-shaped device at least on one end portion and the other end portion of the n-type bar-shaped device and p-type bar-shaped device connected in series.
At this time, the bar-shaped devices at least on one end portion and the other end portion of the n-type and p-type bar-shaped devices connected in series may be exposed on one surface excluding the interconnecting end face of the above described thermoelectric device block, and respective one and the other of said pair of terminal conductors are may be made contact with and provided on the exposed surface of each bar-shaped device.
Alternatively, each bar-shaped device on the above-described one end portion and the other end portion can be exposed to one surface and the other surface of opposing two surfaces excluding the interconnecting end faces, and one and the other of the above-described pair of terminal conductors can be provided in contact with the exposed surfaces of the above described one surface and the other surface of each bar-shaped device to form the thermoelectric device.
Furthermore, it is also acceptable to make a thermoelectric device in a manner such that each bar-shaped device provided on at least one end portion and the other end portion of the n-type and p-type bar-shaped devices connected in series is exposed respectively to the chamfered oblique surface formed between one surface excluding the interconnecting end surface and the adjacent surface, and one and the other terminal conductors are respectively provided in contact with the exposed surface of the chamfered oblique surface and the exposed surface of the other chamfered oblique surface of each above-described bar-shaped device.
Alternatively, it is also possible to make a thermoelectric device in a manner such that the above-described thermoelectric device block has a plurality of device lines in which the n-type bar-shaped devices and the p-type bar-shaped devices align alternately, and consists of a first interconnection conductor connecting each end face of adjacent n-type and p-type bar-shaped devices, which are contained in the same device line among the plural device lines in a parallel direction to the device line, a second interconnection conductor connecting each end face of n-type and p-type bar-shaped devices spreading across the adjacent device line, and a pair of third interconnection conductor connected to each end face of each bar-shaped device provided at least on one end portion and the other portion of n-type and p-type

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