JPH11177154A - Thermoelectric conversion substrate and electric circuit device using the substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convert thermal energy into electric energy with no increase in size of an electric circuit device, by efficiently transferring heat generated at a power source, an electric circuit element, etc., to a thermoelectric conversion function before converting into electric energy. SOLUTION: Between voltage tap terminals 2a and 2b, a Cu conductive pattern 4a and an Ni conductive pattern 4B are alternately arrayed on the surface of a substrate 3, the end parts of both conductive patterns 4a and 4b are jointed together to form a thermo-couple 5 and a connection point 6, and the thermo-couples 5 are gathered at one end part of the substrate 3, while the connection points 6 are gathered at the other end part of the substrate 3. A thermoelectric conversion substrate 1 is integrated into a circuit board, while an electric circuit element with large heat generation is allocated so as to correspond to the region of the thermo-couple 5, and the heat of element is converted into electric energy by the thermoelectric conversion substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermoelectric conversion board and an electric circuit device using the thermoelectric conversion board.

[0002]

2. Description of the Related Art Energy loss in current electronic devices is caused by collector loss of a power transistor, switching elements (such as a CPU) for high-speed operation, and heat generated from elements such as a power resistor. . Efforts have been made to reduce the energy loss due to the heat generated by these elements, but it is generally held that the heat generated by the elements must be allowed in terms of the operation principle. In other words, the emphasis is on how the heat generated by the element is released to the outside of the device by the heat sink or the air-cooling fan and the damage of the element due to the heat is prevented rather than the reduction of the heat generated by the element.

On the other hand, thermoelectric conversion elements are being studied for practical use as a method capable of directly converting heat energy into electric energy, including the use of waste heat from a refuse incinerator (Japanese Patent Laid-Open No. Hei 8 (1996)).
No. 306965). In addition, studies have been made on a method of using micro thermoelectromotive force, such as using a human body temperature to generate micro electric power and using the generated power as a power source for a wristwatch (Japanese Utility Model Application No. 5-63264).

Further, it has been proposed to convert thermal energy generated in a power supply or an electric circuit element into electric energy by using a thermoelectric conversion element, and to return the electric energy to a power supply for the most use (Japanese Patent Application Laid-Open No. Hei 7-1995). -240538).

[0005]

However, so far, the use of thermoelectric conversion elements in electric circuit devices is only conceptual, and how thermoelectric conversion elements are arranged and generated in electric circuit elements and the like. No specific level of how to collect heat energy in the thermoelectric conversion element and convert it to electric energy has been considered. Especially,
As electronic circuits are miniaturized and integrated, it becomes more difficult to secure a space for arranging thermoelectric conversion elements, and it becomes more difficult to use thermoelectric conversion elements.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to efficiently transmit heat generated by a power supply, an electric circuit element, and the like to a thermoelectric conversion function. An object of the present invention is to provide a thermoelectric conversion board and an electric circuit device that can convert heat energy into electric energy without increasing the size of the electric circuit device.

[0007]

DISCLOSURE OF THE INVENTION A thermoelectric conversion substrate according to the present invention is a thermoelectric conversion substrate in which a conductive pattern of two or more different metal materials is formed on the substrate, wherein the conductive pattern forms a joint between different metal materials. It is characterized in that the conductive pattern is provided at a plurality of locations and the conductive pattern is formed so that the total sum of the thermoelectromotive forces generated at the respective junctions is taken out.

By using such a thermoelectric conversion board, heat generated by a power supply, an electric circuit element, or the like can be converted into electric energy. Therefore, the heat dissipated and wasted from a power supply, an electric circuit element, or the like can be converted into electric energy and recovered. Then, the converted electric energy can be supplied to an electric circuit or the like as an auxiliary power supply, or can be reused by charging a secondary battery or the like, so that energy can be saved.

Further, the thermoelectric conversion board converts heat into electric energy, so that it has a heat sink function and can suppress a rise in temperature of a power supply or an electric circuit element.

In addition, the thermoelectric conversion board of the present invention can mount an electric circuit element, a power supply, and the like thereon, or can be laminated and integrated with a circuit board on which the electric circuit element and the like are mounted. The heat generated in the above can be efficiently transmitted to the thermoelectric conversion substrate, and can be efficiently converted into electric energy. In addition, by also serving as a circuit board on which the electric circuit elements and the like are mounted, or by being integrated with the circuit board, it is possible to improve the use efficiency of electric energy without increasing the size of the electric circuit device.

Specifically, joints having a positive thermoelectromotive force in the direction of taking out the thermoelectromotive force are collectively arranged on the substrate, and the thermoelectromotive force is negative in the direction of taking out the thermoelectromotive force. If the joints are collectively arranged in another area, the elements with heat generation among the electric circuit elements mounted on the circuit board can be arranged in or near the positive joint area where the thermoelectromotive force is positive. , Heat of an electric circuit or the like can be efficiently converted into electric energy. On the other hand, in the junction region where the thermoelectromotive force is negative, an element or a heat sink that generates less heat is arranged or exposed in the air, thereby improving the conversion efficiency to electric energy in the positive junction region. Can be

When a sufficient electromotive force cannot be obtained with a thermoelectric conversion substrate formed on a single substrate, the thermoelectric conversion substrate is formed so that the regions where the junctions having positive thermoelectromotive forces are formed overlap each other. When the substrates are stacked and the conductive patterns of each substrate are connected in series, the electromotive force can be increased without increasing the size of the thermoelectric conversion substrate.

Further, if a heat separating means is provided on the circuit board between the heat-generating element on the circuit board and the junction region where the thermo-electromotive force is negative, the heat of the heat-generating element is converted into the junction where the thermo-electromotive force is negative. It is possible to prevent the conversion efficiency from lowering due to leakage into the region.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a plan view showing a thermoelectric conversion substrate 1 according to one embodiment of the present invention. The thermoelectric conversion board 1 has terminals 2a for taking out voltage,
Between 2b, conductive patterns 4a and 4b made of dissimilar metals are formed on the surface of the substrate 3 in a meandering manner. That is, one conductive pattern 4a and the other conductive pattern 4b having a stripe shape are alternately arranged, the ends of both conductive patterns 4a and 4b are joined, and both conductive patterns 4a and 4b are electrically connected in series. Are joined. Then, a junction having a positive thermoelectromotive force with respect to the voltage (thermal electromotive force) extraction direction (that is, a positive thermoelectromotive force between the voltage extraction terminals 2a and 2b with respect to the voltage extraction direction when the temperature becomes high) (Hereinafter, referred to as a thermocouple) 5 is arranged at one end of the substrate 3, and a junction (that is, a high temperature) having a negative thermoelectromotive force in a voltage (thermoelectromotive force) extraction direction is provided. At this time, the voltage extracting terminals 2a, 2
A junction 6 that generates a negative thermoelectromotive force between b; hereinafter, referred to as a connection point) 6 is arranged at the other end of the substrate 3.

Here, as the substrate material, a ceramic substrate having a small thermal conductivity, for example, a ceramic substrate (BAS) mainly containing barium, alumina and silica, or a resin substrate having excellent heat resistance (for example, a Teflon sheet)
Is desirable. Further, as a dissimilar metal forming the conductive patterns 4a and 4b, a combination of dissimilar metals (or alloys) having a large thermoelectromotive force is preferable.
i or a combination of Cu and a Ni alloy can be used. The combination of Cu and Ni has high mass productivity, versatility, and cost advantages.

The region where the thermocouple 5 is formed is defined as a high-temperature region. That is, the area of the thermocouple 5 is located at a position where heat generated from a power supply or an electric circuit element generating a large amount of heat is easily transmitted. The region where the connection point 6 is formed is a low temperature region as much as possible. For example, the temperature is set as close as possible to room temperature by placing the device away from a power source or an electric circuit element generating a large amount of heat, or by contacting a heat sink or the like. When the temperature of the region of the thermocouple 5 becomes high due to the heat of the power supply or the electric circuit element generating a large amount of heat, a thermoelectromotive force is generated in each thermocouple 5, and the sum of the thermoelectromotive forces is applied between the voltage extraction terminals 2a and 2b. Taken out of

Now, n thermocouples 5 are connected in series on the substrate 3 by a Cu conductive pattern 4a and a Ni conductive pattern 4b, and the conversion efficiency of each thermocouple 5, that is, the Seebeck coefficient (the thermocouple 5 is .Alpha. Is the thermoelectromotive force when the unit temperature is increased, and .DELTA.T1, .DELTA.T2,...
Then, the voltage (total thermal electromotive force) Vs generated between the voltage extraction terminals 2a and 2b is as follows: Vs = α (ΔT1 + ΔT2 +... + ΔTn).

In experiments, in the case of the conductive patterns 4a and 4b made of Cu and Ni, the Seebeck coefficient α is about 30 μm.
V / ° C, Cu and constantan (Cu 55%, N
In the case of the conductive patterns 4a and 4b made of (i45% alloy), the Seebeck coefficient α is about 60 μV / ° C. Therefore, in the case of the conductive patterns 4a and 4b made of Cu and Ni, if the average gradient temperature ΔT of each thermocouple 5 is 50 ° C.
In order to obtain a practical electromotive force (about 3 V), about 2000 thermocouples 5 are required as can be understood from the following equation. n = Vs / (αΔT) = 3000 / (0.03 × 50) = 2000

Here, a calculation example is shown for a combination of Cu and Ni, but the combination of conductive pattern materials is not limited to this. For example, in the case of Cu and constantan, the conversion efficiency is approximately doubled as described above, which is effective for downsizing the thermoelectric conversion substrate 1.

(Second Embodiment) In order to obtain a practical voltage (about 3 V), for example, in the case of the conductive patterns 4a and 4b made of Cu and Ni, about 2000 thermocouples 5 are required. For miniaturization, it is effective to stack the thermoelectric conversion substrates 1 as shown in FIG.

In this thermoelectric conversion substrate 1, a plurality of substrates 3a, 3b,... Having thermocouples 5 and connection points 6 formed by conductive patterns 4a, 4b made of dissimilar metals are laminated, and each substrate 3a , 3b,... Are formed at both ends of the conductive patterns 4a, 4b with through holes 7a, 8a, 7b, 8b,. As shown in FIG. 3, each of the substrates 3a, 3b,... Has the same conductive patterns 4a, 4b as in the first embodiment, and a thermocouple 5 is arranged at one end, and at the other end. The connection points 6 are arranged. Furthermore, the upper and lower substrates 3
a, 3b, ..., through holes 7a, 8a, 7b, 8b,
Are different from each other, and the high-voltage side through-hole provided in the lower layer substrate and the low-voltage side through hole provided in the upper layer substrate are provided at the same position, and the through holes 7a and 8a are provided. , 7b, 8b,... Provided on the upper and lower substrates 3a, 3b,.
b and the thermocouple 5 are connected in series. Also, in each of the vertically stacked substrates 3a, 3b,..., The regions where the thermocouples 5 are formed are vertically overlapped with each other.
The area where the connection points 6 are gathered also overlaps each other vertically.

The circuit board 10 on which the electric circuit elements 9 and 9A are mounted is superimposed on the thermoelectric conversion board 1 having the above-mentioned multilayer structure, and the through holes 7 of the uppermost board 3a are formed.
a and the through hole 8d of the lowermost substrate 3d
The electric circuit device 12 is connected to the through holes 11a and 11b. An electric circuit element 9A that generates a large amount of heat, such as a power transistor, is arranged so as to overlap above a region of the thermoelectric conversion substrate 1 where the thermocouple 5 is formed.

(Manufacturing method) Next, the thermoelectric conversion substrate 1
Will be described. The substrate 3 is made of barium, alumina,
A case where the material is formed of a ceramic mainly made of quartz will be described. A paste-like Ni conductive pattern 4b is printed on a ceramic green sheet having a thickness of 50 μm by screen printing and dried. The line width W of the Ni conductive pattern 4b is desirably 150 μm, and the print film thickness is desirably about 20 μm. Next, the paste Cu conductive pattern 4a is printed and dried on the ceramic green sheet so as to connect the ends of the Ni conductive pattern 4b. The line width W of the Cu conductive pattern 4a is desirably 150 μm and the printed film thickness is about 20 μm, similarly to the Ni conductive pattern 4b. The distance S between the conductive patterns 4a and 4b is 1
It was set to 00 μm. According to such a configuration, 10 cm
With the substrate 3a having a size of (= L1) × 20 cm (= L2), 200 thermocouples 5 can be obtained for each substrate, and therefore, the overall conversion efficiency (Seebeck coefficient: nα)
Is 6 mV / ° C.

The through holes 7a, 8a provided at both ends of the conductive patterns 4a, 4b of the substrate 3a are through holes having a diameter of 0.2 mm, and when the conductive patterns 4a, 4b are screen-printed, Cu or Ni paste is embedded at the same time. Substrate 3
Conduction is obtained on both sides of a.

The conductive patterns 4a, 4b and the through holes 7b, 8 are formed in the same manner on the substrates 3b,.
b, ... are formed. In addition, as shown in FIG. 2, the through holes 8a, 7b,..., 7d are aligned so that the connection of the conductive patterns 4a, 4b of the substrates 3a, 3b,. Are laminated and integrated. Finally, the circuit board 10 on which the wiring pattern is formed is stacked on the thermoelectric conversion board 1, and after pressing under pressure, baking is performed at 1000 ° C. for 1 hour in a nitrogen atmosphere. The electric circuit elements 9 and 9A are surface-mounted on the circuit board 10 thus formed on the thermoelectric conversion board 1 in the same manner as a normal circuit board.

If the average gradient temperature ΔT between the connection point 6 and the thermocouple 5 of the substrates 3a, 3b,... On which the large heat-generating electric circuit elements 9A are mounted is about 50 ° C., one thermoelectric conversion A thermoelectromotive force (conversion efficiency) of 6 mV / ° C. is obtained by the substrate 1. When ten such thermoelectric conversion substrates 1 are stacked and integrated, the output voltage Vab obtained is as follows. Vab = 6 [mV / ° C.] · 50 ° C. · 10 [sheets] = 3
[V] That is, a practical power supply of about 1 to 100 mA can be obtained at Vab = 3 V.

FIG. 4 is a diagram for explaining a method of using such a thermoelectric conversion board 1, in which a diode 14 is connected to the thermoelectric conversion board 1 in the forward direction of the voltage generated in the thermoelectric conversion board 1.
And this is connected in parallel with the secondary battery 13.

When the thermocouple 5 of the thermoelectric conversion board 1 is heated by heat radiation from the secondary battery 13 or the electric circuit element 9A that generates a large amount of heat on the circuit board 10, the voltage output terminal of the thermoelectric conversion board 1 is heated. An electromotive force (voltage) is generated between 2a and 2b. When the secondary battery 13 maintains the normal output voltage, no current flows out of the thermoelectric conversion board 1 due to the diode 14, but the output of the secondary battery 13 is lower than the voltage across the thermoelectric conversion board 1. Then, the secondary battery 13 can be charged from the thermoelectric conversion substrate 1. Therefore, energy can be saved, and the period until the secondary battery 13 is recharged can be extended.

Alternatively, when the main electric circuit 15 uses an AC power supply, an electromotive force is generated by heat obtained from the main electric circuit 15 as shown in FIG.
The electric energy can be supplied from the thermoelectric conversion board 1 to the auxiliary DC device 16 such as a display, a buzzer, an actuator, or the like to save power. At this time, rectification of the AC power supply becomes unnecessary.

Further, the thermoelectric conversion board 1 (auxiliary power supply) can continue to supply current by residual heat even after the power is turned off by the heat storage function, so that a new monitoring function such as various monitoring functions after the power is turned off is provided. Application spreads. For example, if the main switch is turned off by mistake or a power failure occurs suddenly, it is possible to avoid a problem that data in the volatile memory or data before being stored in the storage medium is lost. Therefore, it can be used as a substitute for a backup battery or a capacitor, or used for enhancing its functions.

Further, since the heat generated in the electric circuit elements 9 and 9A is converted into electric energy, a rise in temperature of the electric circuit elements 9 and 9A due to heat can be suppressed according to the law of conservation of energy. , 9A from temperature rise.

(Third Embodiment) FIGS. 6A and 6B are perspective views showing an electric circuit device 21 according to still another embodiment of the present invention from the front side and the back side. In this electric circuit device 21, conductive patterns 4a and 4b made of dissimilar metals are wired on the back surface of the substrate 3, and a thermocouple 5 is provided at one end.
Are arranged, and the connection points 6 are arranged at the other end to constitute the thermoelectric conversion board 1. Further, a wiring pattern (not shown) is formed on the surface of the substrate 3 to constitute the circuit board 10. Electric circuit elements 9, 9 mounted on the wiring pattern
Among A, the electric circuit element 9A that generates a large amount of heat is arranged to face the region where the thermocouples 5 are arranged, and the electric circuit element 9 that generates a small amount of heat is opposed to the region where the connection points 6 are arranged. Be placed.

When the average inclination temperature ΔT is large, the thermocouple 5
When the formation density is increased, or when a material having a higher conversion efficiency (Seebeck coefficient) is used as the conductive pattern material, a practical voltage can be obtained without using a laminated structure as in the second embodiment. Can be obtained.

For example, the size of the substrate 3 is 100 mm.
(= L1) × 200 mm (= L2), a 0.6 mm thick Teflon substrate, wiring patterns for mounting the electric circuit elements 9 and 9A are provided on the element mounting surface (front surface), and the back surface is made of dissimilar metal. Conductive patterns 4a and 4b are formed finely. The line width W of each of the Cu and Ni conductive patterns 4a and 4b is 15 μm, and the interval S between the conductive patterns 4a and 4b is 10 μm. According to such a configuration, 2,000 thermocouples 5 can be formed on one substrate 3, and the output voltage (3
V).

(Fourth Embodiment) FIG. 7 is a perspective view showing an electric circuit device 22 according to still another embodiment of the present invention. The thermoelectric conversion substrate 1 used here is formed by forming conductive patterns 4a and 4b made of different metals on a flexible substrate 3 such as polyimide. This flexible thermoelectric conversion board 1 is adhered on the circuit board 10 via silicone grease or the like. The thermocouple 5 of the thermoelectric conversion board 1 is arranged so as to correspond to the position of the electric circuit element 9A that generates a large amount of heat on the circuit board 10, and the area where the thermocouple 5 is formed is an electric circuit that generates a large amount of heat. It overlaps so that it may be directly attached to the element 9A.

(Fifth Embodiment) Conductive patterns 4a, 4
When the temperature at the connection point 6 of b rises, the average slope temperature ΔT decreases, and the output voltage decreases. Therefore, it is desirable that the heat of the electric circuit element 9A, which generates a large amount of heat, is not transmitted to the connection point 6 as much as possible.

For this purpose, the connection point 6 between the place where the electric circuit element 9A generating a large amount of heat is mounted and the thermoelectric conversion board 1
Between the circuit board 10 and the area where
Is provided with a heat separating means such as an opening, a groove, a hole, a notch, and a window for preventing heat transfer, and the electric circuit element 9A which generates a large amount of heat
What is necessary is just to achieve the thermal separation of the connection point 6 from the connection point 6. For example, FIG.
In the electric circuit device 23 shown in FIG. 1, a long hole-shaped opening 24 for thermal separation is provided in the circuit board 10. Or,
The area where the connection points 6 are formed may be made to protrude from the circuit board 10 or may be brought into contact with a heat sink for heat radiation.

[Brief description of the drawings]

FIG. 1 is a plan view showing a thermoelectric conversion substrate according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing an electric circuit device according to another embodiment of the present invention.

FIG. 3 is a perspective view showing one of the substrates.

FIG. 4 is a circuit diagram illustrating a method of using the thermoelectric conversion board according to the first embodiment.

FIG. 5 is a circuit diagram illustrating another method of using the thermoelectric conversion board of the above.

FIGS. 6A and 6B are perspective views showing an electric circuit device according to still another embodiment of the present invention.

FIG. 7 is a perspective view showing an electric circuit device according to still another embodiment of the present invention.

FIG. 8 is a perspective view showing an electric circuit device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion board 3 Substrate 4a, 4b Conductive pattern 5 Thermocouple 6 Connection point

Claims (5)

[Claims] 1. A thermoelectric conversion substrate having a conductive pattern made of two or more different metal materials formed on a substrate, wherein the conductive pattern has a plurality of junctions between different metal materials, and each junction has A thermoelectric conversion substrate, wherein the conductive pattern is formed so as to extract a total of generated thermoelectromotive forces. 2. A junction where a thermoelectromotive force is positive in the direction of taking out the thermoelectromotive force is collectively arranged on the substrate, and a junction in which the thermoelectromotive force is negative in the direction of taking out the thermoelectromotive force is provided. The thermoelectric conversion board according to claim 1, wherein the portions are collectively arranged in another area of the board. 3. A thermoelectric conversion substrate in which a plurality of substrates on each of which a conductive pattern made of a dissimilar metal material is formed are stacked, and the substrate is formed such that regions where bonding portions having a positive thermoelectromotive force are formed overlap each other. The thermoelectric conversion board according to claim 1, wherein the boards are stacked and the conductive patterns of each board are connected in series. 4. A circuit board on which an electric circuit element is mounted is laminated with the thermoelectric conversion board according to claim 2 or 3, and an element of the electric circuit element that generates heat has a thermoelectromotive force in the thermoelectric conversion board. An electric circuit device, wherein a positive junction is arranged so as to face a region where the junction is formed or its vicinity. 5. A heat separating means is provided on the circuit board, between the element having heat generation formed on the circuit board and a region where a junction where the thermoelectromotive force is negative is formed. The electric circuit device according to claim 4, characterized in that: