WO2016195024A1

WO2016195024A1 - Cooling device

Info

Publication number: WO2016195024A1
Application number: PCT/JP2016/066431
Authority: WO
Inventors: 智靖薄井
Original assignee: 株式会社村田製作所
Priority date: 2015-06-04
Filing date: 2016-06-02
Publication date: 2016-12-08
Also published as: JP6414636B2; JPWO2016195024A1

Abstract

The present invention provides a heat transfer device characterized by including: a pair of electrodes; and a dielectric part which is located between the pair of electrodes and which is formed from a material exhibiting an electrocaloric effect, wherein the material exhibiting an electrocaloric effect is represented by formula: (Pb_(1-x)yBa_x)ZrO₃ (in the formula, x is 0.15-0.34, and y is 0.95-1.03).

Description

Cooling device

The present invention relates to a heat transfer device.

In recent years, in electronic devices such as small portable devices (smartphones, tablet PCs) and data servers, the performance of electronic devices is reduced due to the heat generated by the central processing unit (CPU) and hard disk (HDD). Problems such as shortening of life and failure are becoming apparent. For such problems, thermal management in electronic devices is important, but small electronic devices such as smartphones have a small power supply capacity and no space for installing large cooling devices. Therefore, in such a small electronic device, the temperature is currently controlled only by means of heat radiation through the housing, and the heat source and the housing are thermally coupled by a thermal sheet or the like to release heat. On the other hand, large electronic devices such as servers have sufficient power capacity and space, and therefore air conditioning equipment such as air conditioners, Peltier cooling devices, and the like are used.

On the other hand, Non-Patent Document 1 reports Pd _0.8 Ba _0.2 ZrO ₃ as a material having an electrocaloric effect (hereinafter also referred to as “EC effect”). In Non-Patent Document 1, this Pd _0.8 Ba _0.2 ZrO ₃ is formed into a thin film by a sol-gel method, and the EC effect is measured. As a result, it is described that the Pd _0.8 Ba _0.2 ZrO ₃ thin film described in Non-Patent Document 1 shows a large EC effect at 290 K near room temperature. The electrocaloric effect is an endothermic phenomenon resulting from a change in entry peak when the electric dipole moment in a substance is aligned or disturbed by a change in electric field.

In small electronic devices, heat dissipation through the housing as described above is limited because the surface area of the housing is limited. Therefore, the temperature of each heat source is measured, and when the temperature exceeds a predetermined temperature, the performance of the CPU or the like is limited (suppressing heat generation itself). That is, the temperature rise of the housing may hinder the performance of the CPU or the like.

In addition, a large electronic device can obtain a sufficient cooling effect by the air-conditioning equipment as described above, but has a problem that power consumption is very high due to a very large power consumption.

Therefore, development of a small and low power consumption thermal management device is desired.

The inventors of the present invention have focused on the above-mentioned electrocaloric effect and have come to consider using the Pd—Ba—Zr composite oxide exhibiting this electrocaloric effect for a heat transfer device, thereby completing the present invention. A control voltage is required to develop the electrocaloric effect. However, since the Pd—Ba—Zr composite oxide is a ferroelectric substance that is an insulator, power consumption is very small. Therefore, the heat transfer device using the Pd—Ba—Zr composite oxide can be used even in a small portable device having a limited power source capacity.

According to a first aspect of the present invention, there is provided a heat transfer device comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes. ,
The material showing the electrocaloric effect has the following formula:
_{_{(Pb (1-x) y}} Ba x) ZrO 3
(In the formula, x is 0.15 or more and 0.34 or less, and y is 0.95 or more and 1.03 or less)
A heat transfer device is provided that is characterized by the material

According to a second aspect of the present invention, there is provided a heat transfer device comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes. ,
The material showing the electrocaloric effect is a composite oxide containing Pb, Ba and Zr,
The content mole part of Ba with respect to Zr100 mole part is p mole part,
The molar content of Pb with respect to 100 mol of Zr is q mol,
p is 15 or more and 34 or less,
There is provided a heat transfer device characterized in that q is (100−p) × r (wherein r is 0.95 or more and 1.03 or less).

According to the third aspect of the present invention, there is provided an electronic component having the above heat transfer device.

According to the fourth aspect of the present invention, there is provided an electronic apparatus having the above heat transfer device or the above electronic component.

According to the present invention, a Pd—Ba—Zr composite oxide having a specific composition, for example, the formula (Pb _{(1-x) y} Ba _x ) ZrO ₃ (wherein x is 0.15 or more and 0.34 or less) And y is 0.95 or more and 1.03 or less), a small-sized and low power consumption heat transfer device can be provided.

FIG. 1 is a schematic cross-sectional view of a heat transfer device according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a heat transfer device according to the second embodiment of the present invention.

Hereinafter, the heat transfer device of the present invention will be described in detail with reference to the drawings. However, the shape and arrangement of the heat transfer device and each component of the present embodiment are not limited to the illustrated example.

As shown in FIG. 1, the heat transfer device 1a according to the first embodiment of the present invention is a dielectric composed of a pair of electrodes 2 and 4 and a material exhibiting an electrocaloric effect located between the pair of electrodes. And a body portion 6. When a voltage is applied between the electrodes 2 and 4, an electric field is applied to the dielectric portion 6. As a result, the dielectric portion 6 generates heat. When the voltage between the electrodes 2 and 4 is removed, the electric field applied to the dielectric portion 6 disappears. As a result, the dielectric portion 6 absorbs heat.

The material showing the electrocaloric effect used in the present invention is a Pd—Ba—Zr composite oxide. A complex oxide containing Pd, Ba and Zr exhibits an EC effect that generates heat when an electric field is applied and absorbs heat when removed.

In one embodiment, the Pd—Ba—Zr composite oxide has the formula (Pb _{(1-x) y} Ba _x ) ZrO ₃ (wherein x is 0.15 or more and 0.34 or less, and y is 0. 95 or more and 1.03 or less).

X is preferably 0.20 or more and 0.34 or less, more preferably 0.20 or more and 0.30 or less, and even more preferably 0.20 or more and 0.25 or less. By setting the x value in such a range, insulation and a larger EC effect can be obtained. Further, the temperature at which ΔT exhibits a peak value can be adjusted by changing the value of x.

In one embodiment, y is 0.95 or more and less than 1.00, such as 0.95 or more and 0.995 or less, or 0.95 or more and 0.99 or less, or 0.96 or more and less than 1.00; It may be 97 or more and less than 1.00 or 0.98 or more and less than 1.00. By making y less than 1.00, grain growth hardly occurs, a dense ceramic is obtained, insulation is improved, and a larger electric field can be applied.

In another aspect, y is greater than 1.00 and 1.03 or less, preferably 1.005 or more and 1.03 or less, for example 1.010 or more and 1.025 or less. By making y larger than 1.00, the value of ΔT can be made larger.

In one embodiment, the Pd—Ba—Zr composite oxide is a composite oxide containing Pb, Ba and Zr,
The content mole part of Ba with respect to Zr100 mole part is p mole part,
The molar content of Pb with respect to 100 mol of Zr is q mol,
p is 15 or more and 34 or less,
q is (100−p) × r (wherein r is 0.95 or more and 1.03 or less).

P is preferably 20 or more and 34 or less, more preferably 20 or more and 30 or less, and even more preferably 20 or more and 25 or less. By setting the x value in such a range, insulation and a larger EC effect can be obtained. Moreover, the temperature at which ΔT exhibits a peak value can be adjusted by changing the value of p.

In one embodiment, r is 0.95 or more and less than 1.00, for example 0.95 or more and 0.995 or less, or 0.95 or more and 0.99 or less, or 0.96 or more and less than 1.00; It may be 97 or more and less than 1.00 or 0.98 or more and less than 1.00. When r is less than 1.00, grain growth hardly occurs, a dense ceramic is obtained, insulation is improved, and a larger electric field can be applied.

In another embodiment, r is greater than 1.00 and 1.03 or less, preferably 1.005 or more and 1.03 or less, for example 1.010 or more and 1.025 or less. By making r larger than 1.00, the value of ΔT can be made larger.

In one embodiment, the average particle size of the Pd—Ba—Zr composite oxide used in the present invention is preferably 0.5 μm or more, more preferably 10 μm or less, and even more preferably 1 μm or more and 5 μm or less. By having such a particle size, it is possible to further increase the withstand voltage and electrocaloric effect of the dielectric portion. The average particle diameter can be measured using an electron scanning microscope.

The Pd—Ba—Zr composite oxide used in the present invention exhibits an EC effect in the entire temperature range below the crystallization temperature, and particularly exhibits a large EC effect at 353 K to 453 K (80 ° C. to 180 ° C.). Further, the Pd—Ba—Zr composite oxide used in the present invention exhibits a very high insulating property. That is, a high voltage can be applied.

The Pd—Ba—Zr composite oxide used in the present invention can be obtained, for example, by mixing and firing Pb, Ba and Zr oxides or salts. Pb, Ba and Zr contents in Pd—Ba—Zr composite oxide obtained by mixing Pb, Ba and Zr so as to have a predetermined ratio and adjusting the Pb concentration in the atmosphere during firing Can be adjusted.

In the dielectric portion 6, the content of the material exhibiting the electrocaloric effect is 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably. It may be 98% by mass or more, for example, 98.0 to 99.8% by mass. The dielectric portion 6 may be made of a material that substantially exhibits an electrocaloric effect.

The shape of the dielectric portion 6 is not particularly limited, and can be formed into, for example, a sheet shape, a block shape, and other various shapes. The molding method is not particularly limited, and compression, sintering, or the like can be used. Moreover, you may mix and shape | mold with binders, such as resin or glass.

The material constituting the electrodes 2 and 4 is not particularly limited, and examples thereof include Ag, Cu, Pt, Ni, Al, Pd, Au, and alloys thereof (for example, Ag—Pd). Among these, Pt, Ag, Pd, or Ag—Pd is preferable.

The electrodes 2 and 4 may have a function of conveying the amount of heat of the dielectric part in addition to the function of applying an electric field to the dielectric part. Therefore, from the viewpoint of heat transfer, the material constituting the electrode is preferably a material having high thermal conductivity, such as Ag.

The shape of the electrodes 2 and 4 is not particularly limited, but a shape that covers the entire surface of the dielectric portion 6 is preferable from the viewpoint of heat transfer.

The heat transfer device of the present invention uses a dielectric portion made of a material that exhibits an EC effect in the entire temperature range below the crystallization temperature, and particularly exhibits a large EC effect at 353 K to 453 K (80 ° C. to 180 ° C.). ing. Therefore, the heat transfer device of the present invention is preferably used as a heat transfer device, typically a cooling device, in electronic devices such as smartphones, tablet PCs, and data servers that have a temperature of 353 K to 453 K during heat generation. it can.

The temperature range showing a large EC effect can be adjusted by changing the Pb and Ba contents, particularly the Ba content, in the Pd—Ba—Zr composite oxide.

Moreover, the dielectric part in the heat transfer device of the present invention exhibits very high insulation. Accordingly, since the withstand voltage is high and a high voltage can be applied between the electrodes, the change in the electric field can be increased. As a result, it is possible to increase the temperature change (hereinafter also referred to as “ΔT”) due to the change in the electric field.

The insulating property of the dielectric portion can be adjusted by changing the Pb content in the Pd—Ba—Zr composite oxide.

Although the heat transfer device according to the first embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made.

For example, a heat transfer device 1b as shown in FIG. In the heat transfer device 1b according to the second embodiment of the present invention, the plurality of

internal electrodes

12a and 12b and the plurality of dielectric portions 14 are alternately stacked. The

internal electrodes

12a and 12b are electrically connected to

external electrodes

16a and 16b disposed on the end face of the heat transfer device 1b, respectively. When a voltage is applied from the

external electrodes

16a and 16b, an electric field is formed between the

internal electrodes

12a and 12b. Due to this electric field, the dielectric portion 14 generates heat. When the voltage is removed, the electric field disappears, and as a result, the dielectric portion 14 absorbs heat.

By adopting such a structure, it becomes possible to apply a strong electric field to the dielectric portion 14, and a larger ΔT can be obtained. Further, since the internal electrode also functions as a heat propagation path to the inside of the dielectric portion, efficient heat management is enabled.

In the

heat transfer devices

1a and 1b described above, the electrode and the dielectric portion are substantially in contact with each other, but the present invention is not limited to such a structure, and an electric field can be applied to the dielectric portion. Any structure can be used. The

heat transfer devices

1a and 1b have a rectangular parallelepiped block shape, but the shape of the heat transfer device of the present invention is not limited thereto, and may be, for example, a cylindrical shape or a sheet shape. Etc. may be included.

The heat transfer device of the present invention absorbs heat generated by the heat source mainly when the electric field is released and absorbs heat, or when the temperature of the heat transfer device decreases due to this heat absorption. The heat transfer device of the present invention releases absorbed heat to the outside mainly when an electric field is applied to dissipate heat.

When absorbing the heat generated by the heat source, the heat transfer device of the present invention is preferably located in the vicinity of the heat source, more preferably directly or via a member having high thermal conductivity.

In one aspect, when dissipating the absorbed heat, the heat transfer device of the present invention is preferably located away from the heat source. More preferably, when dissipating the absorbed heat, the heat transfer device of the present invention is located away from the heat source, and in the vicinity of another cooling device that assists heat dissipation of the heat transfer device of the present invention. Or positioned to contact the cooling device directly or through a member with high thermal conductivity.

In another aspect, the heat transfer device of the present invention is preferably located in the vicinity of the heat source and more preferably efficiently absorbed heat while still in direct contact or through a member with high thermal conductivity. Can be released to the outside. Since the temperature of the heat transfer device of the present invention decreases when the electric field is released, the temperature difference from the heat source becomes larger, and heat generated by the heat source can be absorbed more efficiently. Further, the heat transfer device of the present invention rises in temperature when an electric field is applied, and becomes higher than the external temperature, or the temperature difference from the external becomes larger, so that the heat can be more efficiently transferred to the outside. Can be dissipated. Therefore, the heat transfer device of the present invention can be used as a cooling device.

Preferably, the heat transfer device of the present invention is connected to a heat conducting member and can release heat through this. The heat conducting member itself can function as a cooling device that dissipates heat to the outside. In another aspect, it may be connected to other cooling devices and function to transport heat absorbed from the heat transfer device of the present invention to the other cooling devices. Thus, more efficient cooling is attained by connecting the heat transfer device of the present invention to the heat conducting member.

The present invention also provides an electronic component having the cooling device of the present invention and an electronic apparatus having the cooling device or the electronic component.

Although it does not specifically limit as an electronic component, For example, a central processing unit (CPU), a hard disk (HDD), a power management IC (PMIC), a power amplifier (PA), a transceiver IC, a voltage regulator (VR), etc. Light emitting elements such as integrated circuits (ICs), light emitting diodes (LEDs), incandescent bulbs, semiconductor lasers, parts that can be heat sources such as field effect transistors (FETs), and other parts such as lithium ion batteries, substrates, heat sinks And parts commonly used in electronic devices such as housings.

The electronic device is not particularly limited, and examples thereof include a mobile phone, a smartphone, a personal computer (PC), a tablet terminal, a hard disk drive, and a data server.

-Preparation of heat transfer device The raw materials of Pb ₃ O ₄ , BaCO ₃ , and ZrO ₂ were weighed so as to have the composition shown in the following table, and pulverized and mixed with partially stabilized zirconia (PSZ: Partial Stabilized Zirconia) balls. After drying, it was calcined at 1000 ° C. for 4 hours, and an organic solvent and a binder were added to the calcined powder and pulverized and mixed to form a slurry. A green sheet (thickness: 40 μm) was formed from the obtained slurry by a doctor blade method. A Pt paste was screen printed on the green sheet. The green sheet on which the Pt paste was printed was pressure-bonded so as to have a layer structure as shown in FIG. 2, stacked, and then cut to produce a green chip (5 mm × 7 mm × 0.5 mm).

A green chip (2 g) was degreased at 450 ° C. to 550 ° C. and then enclosed with 10 g of PbZrO ₃ powder in an alumina hermetic sheath and baked at 1300 ° C. for 4 hours to produce a laminate chip. An Ag paste was applied to both ends of the obtained laminate chip, baked to form external electrodes, and a sample (heat transfer device) having the structure shown in FIG. 2 was manufactured. The composition of the sample was confirmed using ICP (inductively coupled plasma emission spectroscopy) and XRF (fluorescence X-ray measurement) in combination.

(Evaluation)
-Insulation evaluation The insulation was evaluated by PE hysteresis measurement by the PUND method. A sample in which a leakage current component was observed at 10 MV / m was marked with x, and a sample that was not observed was marked with ◯. The results are shown in the table below.

-Operating temperature The temperature dependence of the dielectric constant was measured, and the temperature at which the value of the dielectric constant was maximum was determined as the operating temperature. The results are shown in the table below.

・ Evaluation of electrical calorific effect (ΔT evaluation)
An ultrafine thermocouple was directly attached to the sample, and the temperature change (ΔT) at the time of applying and removing the electric field was measured. The results are shown in the table below.

In the table below, G indicates that the operating temperature is in the range of 353 K to 453 K (80 ° C. to 180 ° C.), no leakage current is observed in the insulation evaluation, and ΔT at 10 MV / m is 1.0 K or more. Those that did not satisfy even one were judged as NG. “*” Indicates a comparative example, “−” indicates that measurement is not performed, and “x” in the column of ΔT indicates that measurement is not possible.

From the above results, it was confirmed that the sample within the scope of the present invention has high insulation and a large ΔT at an operating temperature suitable for use in electronic equipment. In particular, it was confirmed that Sample Nos. 8 to 11, 14 to 17, and 20 to 23 maintained insulation even at 30 MV / m and exhibited a large ΔT.

The heat transfer device of the present invention can be used as a cooling device for various electronic devices, for example, small electronic devices such as mobile phones in which the problem of countermeasures against heat has become prominent.

DESCRIPTION OF

SYMBOLS

1a, 1b ... Heat transfer device 2, 4 ... Electrode 6 ...

Dielectric part

12a, 12b ... Internal electrode 14 ...

Dielectric part

16a, 16b ... External electrode

Claims

A heat transfer device comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes,
The material showing the electrocaloric effect has the following formula:
(Pb (1-x) y Ba x) ZrO 3
(In the formula, x is 0.15 or more and 0.34 or less, and y is 0.95 or more and 1.03 or less)
A heat transfer device, characterized by being a material indicated by
The heat transfer device according to claim 1, wherein y is 0.95 or more and less than 1.00.
The heat transfer device according to claim 1, wherein y is greater than 1.00 and 1.03 or less.
A heat transfer device comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes,
The material showing the electrocaloric effect is a composite oxide containing Pb, Ba and Zr,
The content mole part of Ba with respect to Zr100 mole part is p mole part,
The molar content of Pb with respect to 100 mol of Zr is q mol,
p is 15 or more and 34 or less,
A heat transfer device, wherein q is (100−p) × r (wherein r is 0.95 or more and 1.03 or less).
The heat transfer device according to claim 4, wherein r is 0.95 or more and less than 1.00.
The heat transfer device according to claim 4, wherein r is greater than 1.00 and 1.03 or less.
The heat transfer device according to any one of claims 1 to 6, wherein the electrode is made of Pt, Ag, Pd, or Ag-Pd.
The heat transfer device according to any one of claims 1 to 7, wherein a plurality of electrodes and a plurality of dielectric portions are alternately laminated.
The heat transfer device according to any one of claims 1 to 8, which is a cooling device.
An electronic component comprising the heat transfer device according to any one of claims 1 to 9.
An electronic device comprising the heat transfer device according to any one of claims 1 to 9 or the electronic component according to claim 10.