JP5008617B2 - Method for improving heat dissipation efficiency of electronic equipment in which heat source is covered with resin member, wavelength selective heat radiation material and method for producing the same - Google Patents

Description

  The present invention relates to a method for improving the heat dissipation efficiency of an electronic device, a wavelength-selective heat radiation material, and a method for producing the same, particularly for an electronic device in which a heat source is covered with a resin member having a specific infrared transmission wavelength region. The present invention relates to a method for improving heat dissipation efficiency of an electronic device by applying a wavelength-selective heat radiation material having a heat radiation surface in which a large number of microcavities forming a periodic surface fine unevenness pattern are two-dimensionally arranged.

  In recent years, the trend toward smaller, lighter, faster, and more multifunctional electronic devices, especially information processing equipment, has promoted higher speed and higher integration of semiconductor elements, which has increased the heat generation density of each element. Concentration of local fever has occurred. For this reason, problems such as an increase in the failure rate of semiconductor components due to such a temperature rise and a shortened life of each component have occurred.

  Furthermore, from the viewpoint of emphasizing environmental friendliness, it is difficult to solve the above-mentioned problems only by heat radiation by fans, which has been performed in the past, such as noise problems of equipment-enclosed cooling fans. As a heat dissipation means, a new heat dissipation measure using heat conduction or heat radiation is desired.

  However, as a recent trend, various types of resin are used for electronic equipment-related parts, so due to the effect of the poor thermal conductivity of the resin, heat measures such as sufficient heat dissipation should be taken only by thermal conduction. Is in a difficult situation. In other words, the heat source of an electronic device housed in a material with poor thermal conductivity such as a plastic material is captured by the resin cover that covers the heat source even if the heat radiation is efficiently radiated to store heat. As a result, the temperature rise of the device due to the heat source cannot be sufficiently suppressed.

  On the other hand, in recent years, it has been described in Japanese Patent No. 3472838, Japanese Patent Application Laid-Open No. 2002-069961 and Japanese Patent Application Laid-Open No. 2004-238230 (hereinafter referred to as “Patent Document 1,” “Patent Document 2,” and “Patent Document 3”). As described above, a technology has been developed in which a thermal energy radiated by using a wavelength-selective thermal radiation material is selected and concentrated to a specific wavelength, thereby improving heat utilization efficiency and the like.

However, since these technologies were considered to be technologies that can be used to efficiently supply "thermal energy" to devices, etc., in principle, it is not possible to promote the accumulation of heat by using such technologies. Even in such a case, it has been considered disadvantageous to use it to suppress heat accumulation in the device and to efficiently “release heat energy” from the device by heat radiation or the like.
Japanese Patent No. 3472838 JP 2002-069691 A JP 2004-238230 A

  Therefore, the present invention is described in Patent Documents 1-3 as means for efficiently and effectively releasing heat from a heat source of an electronic device housed in a material having poor thermal conductivity such as a plastic material. To improve the heat transmission efficiency of plastics such as plastic materials using such wavelength-selective thermal radiation materials, and to improve the heat dissipation efficiency of electronic equipment whose heat source is covered with resin material, wavelength selection An object of the present invention is to provide a heat-radiating material and a method for producing the same.

  As a result of intensive studies on the wavelength-selective heat radiating material and the structure of the electronic device covered with the wavelength-selective heat radiating material and the resin member, the inventors have found that the heat conductivity of the plastic material or the like As a means of effectively releasing the heat of the heat source of the electronic device housed in a bad material, a technology that emits specific heat radiation light using a wavelength selective heat radiation material is used. By controlling the wavelength range of emitted thermal radiation (infrared rays) to a specific wavelength range, heat storage due to infrared absorption of the resin is prevented (transparent), and heat dissipation of electronic equipment whose heat source is covered with resin members I found that efficiency can be improved.

  1 and 2 show the wave number (νcm-1) of the infrared ray irradiated on the horizontal axis, the infrared ray transmittance (T%) on the vertical axis, and an epoxy resin used as a component of electronic equipment by infrared spectroscopy. The result of having investigated the infrared absorption spectrum about resin materials, such as polycarbonate resin, is shown. When the infrared absorption spectrum of epoxy resin or polycarbonate resin is observed, as shown in FIGS. 1 and 2, infrared rays are absorbed in the wavelength range larger than this, with infrared wavelengths of 6 to 7 μm being the boundary, and in the wavelength range below this, the infrared rays are almost absorbed. There is a tendency to permeate without being absorbed.

  Therefore, in the present invention, a wavelength-selective thermal radiation material that radiates only infrared rays within the infrared transmission wavelength region of the resin material as described above is applied to the infrared rays emitted from the heat source, and the wavelength-selective thermal radiation is applied. By making the resin material covering the heat source of the electronic device substantially transparent to the infrared rays radiated from the heat source through the material, the heat energy radiated from the heat source can be efficiently dissipated.

  Specifically, according to the present invention, in an electronic device in which a heat source is covered with a resin member having a specific infrared transmission wavelength region, a number of microcavities forming a periodic surface fine unevenness pattern are two-dimensionally arranged. A wavelength-selective heat radiation material having a heat radiation surface is disposed between the heat generation source and the resin member so as to cover the heat generation source, and the heat radiation light emitted from the heat generation source is used as the wavelength-selective heat radiation material. Heat radiation from the heat radiation surface of the wavelength-selective heat radiation material toward the resin member, and selectively radiating heat radiation light having a wavelength corresponding to the infrared transmission wavelength region of the resin member. This is a method for improving efficiency, and preferably, the thermal radiation light is an infrared ray having a great influence on heat transfer.

  According to another aspect of the present invention, the wavelength selective heat used for improving the heat radiation efficiency of the heat source in an electronic device in which the heat source is covered with a resin member having a specific infrared transmission wavelength region. A plurality of microcavities substantially two-dimensionally arranged to form a fine uneven pattern that is periodically repeated on a plane, and is formed on and covers the microcavities. There is provided a wavelength selective heat radiation material comprising a heat radiation surface comprising a coating layer, and the heat radiation surface selectively emits heat radiation light corresponding to the infrared transmission wavelength region of the resin member. The

  In the present invention, the wavelength-selective heat radiation material is preferably arranged so as to cover the heat source between the heat source and the resin member in order to maximize the heat radiation efficiency of the heat source. The thermal radiation light is preferably intended for infrared rays having a large influence on heat transfer.

  There are a number of surface textured microcavities on the heat emitting surface of the inventive material. These microcavities have a rectangular or circular shape so as to have a predetermined opening ratio and a predetermined aspect ratio, and are substantially the same as the wavelength of the infrared transmission wavelength region of the resin member covering the heat source. It is preferable that it is formed in a cycle or a cycle shorter by 1 μm.

  If the period of the microcavity is set to be substantially the same as the wavelength of the infrared transmission wavelength region of the resin member covering the heat source, surface plasmon resonance occurs between the periodic structure and the electromagnetic field of the heat radiation light. This is because the emissivity in the infrared transmission wavelength band of the member increases (resonance effect).

  Also, if the microcavity has a period shorter by 1 μm than the wavelength of the infrared transmission wavelength region of the resin member covering the heat source, the wavelength of the mode having the strongest intensity among the electromagnetic waves confined in the microcavity And the wavelength of the infrared transmission wavelength region of the resin member can be matched. As a result, the emissivity increases in the infrared transmission wavelength region of the resin member (cavity effect).

  The microcavities are preferably arranged in a lattice pattern on the radiation surface in a planar view. This is because the lattice arrangement efficiently increases the emissivity of the thermal energy rays. Note that the present invention is not limited to the lattice arrangement, and may be other arrangements such as a honeycomb structure.

  Moreover, it is preferable that a coating layer (surface substance of a microcavity) consists of a metal material whose emissivity of the infrared region with a wavelength of 1-10 micrometers is 0.4 or less. This is because if the emissivity in the infrared region exceeds 0.4, there is a disadvantage that the selective radiation characteristic is deteriorated.

  It is preferable that the microcavity has a period of 4 to 7 μm so that only infrared rays in the infrared transmission wavelength region of the resin member covering the heat source can be selectively emitted. This is because although the infrared absorption wavelength range and the transmission wavelength range may be slightly different depending on the type of resin, the resin material currently used as a member for electronic devices often exhibits the above wavelength range.

  The cavity opening ratio a / Λ (see FIG. 2) is preferably in the range of 0.5 to 0.9. This is because when the aperture ratio a / Λ is less than 0.5, there is a disadvantage that the selectivity of heat radiation is lowered. On the other hand, if the aperture ratio a / Λ exceeds 0.9, there is a disadvantage that the thermal stability of the microstructure is lowered.

  Moreover, it is preferable to make the aspect ratio d / a (refer FIG. 2) of a microcavity into the range of 0.8-3.0. This is because when the aspect ratio d / a is less than 0.8, there is a disadvantage that the selective radiation intensity is lowered. On the other hand, if the aspect ratio d / a exceeds 3.0, there arises a disadvantage that the production of the material is extremely difficult.

  The semiconductor substrate of the wavelength-selective heat radiation material used in the present invention is preferably a single semiconductor such as Si or Ge, or a refractory metal such as W, Mo, Ta, or Nb, but is not necessarily a refractory metal. Absent. This is because a semiconductor such as Si or a metal such as tungsten has a unique thermal radiation band in the visible light and infrared regions.

  Note that, when a fine surface processing is performed on a metal substrate, a fast atom beam etching technique is used. The fast atomic beam etching technology is Kanamori, K .; Hane, H .; Sai and H.M. Yugami, 100 nm period silicon antireflecting structures fabricated using a porous alumina mask, Appl. Phys. Lett. 78 (2001) 142-143.

  The coating layer is preferably made of a low-resistivity metal excellent in electrical conductivity such as Pt, Au, Ag, Cr, Cu, Al, or Zn, or an alloy containing these metals as a main component.

The method for producing a wavelength-selective heat radiation material according to the present invention is used to improve the heat radiation efficiency of the heat source in an electronic device in which the heat source is covered with a resin member having a specific infrared transmission wavelength region. A method for producing a wavelength selective thermal radiation material comprising:
(A) opening a large number of periodically arranged holes opened in the metal thin film sheet using a photolithography process, thereby obtaining a porous metal mask;
(B) A resist is applied to a semiconductor substrate, the porous metal mask is disposed so as to face the resist coating film, and pattern exposure is performed by irradiating the resist coating film with light having a predetermined wavelength through the periodic array holes. Steps,
(C) contacting the resist coating film with a developer, and developing a pattern exposure latent image in the resist coating film;
(D) pattern-etching the semiconductor substrate using a predetermined etching method, thereby forming a fine concavo-convex pattern on the surface of the semiconductor substrate; and (e) removing the resist coating film from the semiconductor substrate. A metal coating film is laminated on the fine concavo-convex pattern on the surface of the semiconductor substrate using a physical vapor deposition method or a chemical vapor deposition method, thereby periodically two-dimensionally arranging the semiconductor substrate on the semiconductor substrate. Obtaining a modified microcavity;
It is characterized by comprising.

  In the above step (a), it is preferable that the periodic array holes of the porous metal mask have substantially the same period or 1 μm shorter than the wavelength of the infrared transmission wavelength region of the resin member covering the heat generation source. This is because when a microcavity is formed using a mask having such periodic array holes, thermal radiation of a specific wavelength can be expressed by the above-described resonance effect and cavity effect.

  According to the present invention, for an electronic device in which a heat source is covered with a resin member having a specific infrared transmission wavelength range, a heat in which a number of microcavities forming a periodic surface fine unevenness pattern are two-dimensionally arranged. A method for improving heat dissipation efficiency of an electronic device by applying a wavelength-selective heat radiation material having a radiation surface, a wavelength-selective heat radiation material, and a method for manufacturing the same are provided.

  As a result, according to the present invention, it is possible to sufficiently dissipate and cool an electronic device having a heat source without using a special device such as a cooling fan, and it is possible to manufacture a compact electronic device having a high degree of freedom in design. enable.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the examples shown below, and various modifications can be made without departing from the technical idea of the present invention.

1 and 2 show the infrared absorption spectrum of the resin material by irradiating an epoxy resin and a polycarbonate resin used as components of an electronic device with infrared rays and dispersing transmitted light. The horizontal axis represents the wave number (νcm ⁻¹ ) of irradiated infrared rays, and the vertical axis represents infrared transmittance (T%). As a result, as shown in FIGS. 1 and 2, the epoxy resin or the polycarbonate resin absorbs infrared rays in the wavelength range larger than this with the infrared wavelength of 6 to 7 μm as a boundary, and absorbs almost in the shorter wavelength range. It turns out that there is a tendency to permeate without.

  In order to simulate the thermal radiation characteristics of the microcavity periodic structure, a numerical analysis based on the RCWA (Rigorous Coupled-Wave Analysis) method was performed. As a result, it was demonstrated that the microcavity periodic structure has a spectral selectivity suitable for thermal radiation for substantially transparentizing the resin member with respect to infrared rays. The observed radiation band is presumed to be generated from the resonance effect between the electromagnetic wave and the surface standing wave and the standing wave mode generated in the microcavity.

  Next, an outline of numerical analysis based on the RCWA method will be described.

Numerical analysis The phenomenon that wavelength selective absorption characteristics can be obtained by periodic surface microstructure is explained by absorption by surface plasmon induced by periodic structure and absorption of standing wave mode by cavity structure. Since it is a complex event that also involves physical properties, quantitative explanation has not yet been made, and it is difficult to evaluate characteristics analytically.

[Analysis model]
Therefore, the present inventors have determined the optimal shape model of the microcavity periodic structure using the Rigorous Coupled-Wave Analysis (hereinafter referred to as RCWA method), which is an exact solution of the Maxwell equation. As shown in FIG. 3, the optimum shape model 1 has a structure in which rectangular microcavities 2 having an opening diameter a and a depth d are two-dimensionally arranged vertically and horizontally at a period Λ. These microcavities 2 are formed on one side of a silicon substrate 3 and covered with platinum 4.

[Calculation condition]
Numerical analysis based on the RCWA method was performed using an analysis model having the above structure, and the optical characteristics of a material having a submicron periodic structure on the surface were evaluated by simulation. In the RCWA method, since the dielectric constant distribution of the material is expressed by Fourier series expansion, analysis of an arbitrary periodic structure is possible. By inputting the geometric constant and the optical constant (complex refractive index) of the material and solving the Maxwell equation exactly, the response of the incident wave can be obtained. The RCWA method is a method for analyzing a general three-dimensional diffraction grating problem. The dielectric constant distribution in the fine structure region is expressed by Fourier expansion. The analysis accuracy depends on the number of spatial harmonic expansion terms of the electromagnetic field. In the present invention, a two-dimensional periodic structure is the object of analysis, but calculation is performed in consideration of a total of 225 diffracted waves in the x-axis and y-axis directions up to plus or minus 7th order, and the solution converges sufficiently. confirmed.

  Diffraction orders up to plus or minus 7th order are considered in the x-axis and y-axis directions, so the present invention calculates the diffraction efficiency for each wavelength of 225 diffraction orders for each wavelength. The present inventors have confirmed that the solution converges sufficiently under these conditions. The input data includes only the conditions of the incident wave, the structural profile, and the state of the optical constants (n, k) of the material, and no variable parameters are used in the calculation. The diffraction efficiency for each diffraction order is given by D.E. W. Lynch and W.M. R. Hunter, Handbook of Optical Constants of Solids I, E .; D. Palik, ed. (Academic Press, New York, 1985), pp. 333-341, and D.I. F. Edwards, Handbook of Optical Constants of Solids I, E.E. D. Palik, ed. (Academic Press, New York, 1985), pp. 547-569, calculated at room temperature platinum and Si optical constants, respectively. The calculation follows the procedure described in the specification of Japanese Patent Application No. 2002-131833 filed earlier by the present inventors.

  FIG. 4 is a spectral radiation characteristic diagram showing the result of numerical analysis of the structural model shown in FIG. 3 by the RCWA method, with the wavelength λ (μm) on the horizontal axis and the spectral emissivity on the vertical axis.

  The spectral emissivity was simulated by changing the period Λ of the rectangular microcavity to (1) 4.8 μm, (2) 6.3 μm, and (3) 7.0 μm. That is, (1) the period Λ = 4.8 μm is obtained by setting the radiation peak of the wavelength-selective heat radiation material in the wavelength region where the absorption of the resin is the smallest, and (2) the period Λ = 6.3 μm The radiation peak of the wavelength selective thermal radiation material is set in the wavelength region where the absorption energy of the black body is small and the radiation energy is large near the radiation peak of the black body at the set temperature, and (3) the period Λ = 7.0 μm is The radiation peak of the wavelength selective heat radiation material is set to the absorption peak of the resin.

[Calculation result]
From the calculation results, the emission peak appears at a wavelength that is about the same as the period Λ and a wavelength that is about 1 μm larger than the period Λ, and from the calculation results, when the period Λ = 6.3 μmΛ = or Λ = 4.8 μm, the infrared absorption of epoxy It was found that the wavelength can be almost controlled in the wavelength range where the coefficient is small.

EXAMPLE Next, a mask (reticle) for use in the manufacture of a wavelength-selective thermal radiation material (selective emitter) is prepared, and the wavelength-selective thermal radiation material (selective emitter) according to the present invention is used with the mask (reticle). ) Was produced.

  Specifically, (a) using a photolithography process to form a large number of periodically arranged holes that open in the metal thin film sheet, thereby obtaining a porous metal mask; and (b) applying a resist to the silicon substrate. A step of arranging the porous metal mask so as to face the resist coating film, and irradiating the resist coating film with light having a predetermined wavelength through the periodic array holes, and pattern exposing, (c) the resist coating film And a step of developing a pattern exposure latent image in the resist coating film, and (d) pattern-etching the semiconductor substrate using a predetermined etching method, thereby finely forming the surface of the silicon substrate. Forming a concavo-convex pattern; and (e) removing the resist coating from the silicon substrate, and performing physical vapor deposition or chemical vapor deposition. A metal coating film made of platinum is laminated on the fine concavo-convex pattern on the surface of the silicon substrate using the method, thereby obtaining microcavities periodically arranged in a two-dimensional manner on the silicon substrate, A wavelength selective thermal radiation material according to the invention was made.

  A more specific mask (reticle) manufacturing method and wavelength-selective thermal radiation material (selective emitter) manufacturing method are disclosed in Japanese Patent Application No. 2004-238230 (Patent Document 3) previously filed by the present inventors. Since it is described in detail in the specification, the mask manufacturing method and the wavelength selective thermal radiation material manufacturing method described in Patent Document 3 are adopted here as references.

FIGS. 5 and 6 are scanning electron micrographs obtained by enlarging the surface of the wavelength-selective thermal radiation material (selective emitter) according to the present invention to a magnification (1 × 10 ⁴ ) of about 10,000 times, and FIG. = 6.3 μm, aperture diameter a = 4.80 μm, FIG. 6 is produced under the setting conditions of period Λ = 4.8 μm and aperture diameter a = 3.84 μm. 5 and 6, it can be confirmed that both microcavities have a substantially rectangular shape and are periodically arranged in a vertical and horizontal lattice pattern.

Heat dissipation effect evaluation test
[Evaluation equipment]
Next, the heat radiation effect evaluation apparatus 5 shown in FIG. 7 is manufactured, and the heat radiation effect when the heater is covered with the wavelength selective heat radiation material (selective emitter) according to the present invention is applied to the heater covered with the resin member. evaluated.

  The heat radiation effect evaluation apparatus 5 shown in FIG. 7 has a heat generating body 10 in which a wavelength-selective heat radiation material or the like is applied to the surface of a heater and the outside is covered with a resin member, and the heat generating body 10 is insulated from the external atmosphere. In order to do so, it is composed of a heat insulating box 20 covering its periphery, and a thermotracer 30 and thermocouples 31a-31d for measuring thermal radiation intensity (temperature) from the heating element 10.

  The heating element 10 includes a heater 11 sandwiched between two aluminum plates 12, and the surface of the aluminum plate 12 of the heater has a heat radiating surface in which microcavities are two-dimensionally arranged. 13 and a structure in which the outside is surrounded by a resin member 14 made of epoxy resin. The thermotracer 30 measures the surface temperature of the resin member 14 covering the heating element 10, and the thermocouples 31a to 31d measure the temperature inside the housing, the temperature inside the resin member, and the temperature outside the resin member, respectively.

[Evaluation materials]
In order to promote the transmission of infrared rays to the resin member 14, the surface condition of the member covering the heater unit 11 is that the aluminum plate 12 of the heater unit 11 is used as it is without applying the wavelength selective heat radiation material. And a silicon substrate coated with a high-radiation paint (trade name: COOLTECH, Okitsumo Co., Ltd.) exhibiting a high emissivity over the entire infrared wavelength range as a wavelength-selective thermal radiation material As a wavelength-selective heat radiating material according to the present invention, a heat radiating material in which the period Λ of the rectangular microcavity produced by the above-described method is 4.8 μm (Example 1) is prepared. ), 6.3 μm heat radiation material (Example 2), and 7.0 μm heat radiation material (Example 3).

[test results]
Each of the above evaluation materials is heated under the conditions of heater input 60 mA, 36 V (as a result, the temperature of the heater unit 11 at that time is approximately 90 ° C.). did. The results are shown in Table 1.

  From Table 1, the wavelength-selective heat radiation material of Example 1-3 according to the present invention was obtained by applying the wavelength-selective heat radiation material (selective emitter) of Comparative Example 1 and the high emissivity of Comparative Example 2. Even when compared with a silicon substrate coated with a high-radiation paint indicating the above, it has been found that the heat source has a high heat radiation effect without increasing the temperature of the resin member 14 covering the heat generating element 10. In particular, when the period Λ of the rectangular microcavity of Example 1 is 4.8 μm with respect to the heating element 10 covered with the resin member 14, the heat radiation from the heater unit 11 is most effectively radiated. I found that I can do it.

  As described above in detail, the present inventors have demonstrated that the two-dimensional surface microstructure (microcavity) selectively emits thermal energy rays in the infrared transmission wavelength region of the resin member covering the heat source. . Moreover, it was confirmed by numerical analysis based on the RCWA algorithm that the surface microstructure having the rectangular microcavity has good spectral selectivity.

It is an infrared absorption spectrum characteristic diagram of an epoxy resin by infrared spectroscopy. It is an infrared absorption spectrum characteristic diagram of polycarbonate resin by infrared spectroscopy. It is a schematic diagram of the analysis model used for the computer simulation numerical analysis method (RCWA method). It is a characteristic diagram which shows the correlation of the wavelength / spectral emissivity obtained by carrying out the numerical analysis about the analysis model when changing the period (LAMBDA) of a rectangular cavity. It is the scanning electron microscope (SEM; magnification 10000 times) photograph which expanded the surface of the wavelength selective thermal radiation material (selective emitter) of this invention of setting period (LAMBDA) = 6.0micrometer. It is the scanning electron microscope (SEM; magnification of 10000 times) photograph which expanded the surface of the wavelength selective thermal radiation material (selective emitter) of this invention of setting period (LAMBDA) = 4.8micrometer. 1 is a schematic view (including a partial cross-sectional view) of a heat dissipation effect evaluation apparatus for a wavelength-selective heat radiation material (selective emitter) according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optimal shape model 2 ... Rectangular microcavity 3 ... Silicon substrate 4 ... Platinum coating layer 5 ... Radiation effect evaluation apparatus 10 ... Heating element 11 ... Heater member 12 ... Aluminum plate 13 ... Wavelength selective thermal radiation material 14 ... Resin member 20 ... Insulation box 30 ... Thermo tracer 31a ... Thermocouple (heater)
31b ... Thermocouple (inside the housing)
31c ... Thermocouple (resin member inner surface)
31d ... Thermocouple (resin member outer surface)

Claims (12)

In an electronic device in which a heat source is covered with a resin member having a specific infrared transmission wavelength range,
A wavelength-selective heat radiation material having a heat radiation surface in which a number of microcavities forming a periodic surface fine unevenness pattern are two-dimensionally arranged is covered between the heat generation source and the resin member. Placed in
Thermal energy from the heat source is input to the wavelength selective heat radiation material by heat transfer or heat radiation, and infrared rays of the resin member are directed from the heat radiation surface of the wavelength selective heat radiation material toward the resin member. A method for improving the heat dissipation efficiency of the electronic device by selectively radiating thermal radiation corresponding to a transmission wavelength region.   The method according to claim 1, wherein the heat radiation light is infrared light. In an electronic device in which a heat source is covered with a resin member having a specific infrared transmission wavelength region, a wavelength-selective heat radiation material used for improving the heat dissipation efficiency of the heat source,
The wavelength-selective heat radiation material is disposed between the heat source and the resin member so as to cover the heat source, and substantially forms a fine uneven pattern that is periodically repeated on a plane. A heat radiating surface comprising a plurality of microcavities arranged two-dimensionally and a coating layer formed on and covering the microcavities;
The wavelength selective heat radiation material, wherein the heat radiation surface selectively emits heat radiation light corresponding to an infrared transmission wavelength region of the resin member. The wavelength selective heat radiation material according to claim 3 , wherein the heat radiation light is infrared light. The microcavity opens in a rectangular shape or a circular shape so as to have a predetermined opening ratio and a predetermined aspect ratio, and has substantially the same period as the wavelength of the infrared transmission wavelength region of the resin member covering the heat source. The wavelength-selective heat radiation material according to any one of claims 3 to 4 , wherein the wavelength-selective heat radiation material is formed with a period shorter by 1 μm. The microcavities, wavelength-selective thermal radiation material according to one of claims 3 to 5, characterized in that it is arranged in a lattice pattern on the emitting surface in a plane field. The wavelength-selective thermal radiation material according to any one of claims 3 to 6 , wherein the coating layer is made of a metal material having an emissivity of 0.4 or less in an infrared region having a wavelength of 1 to 10 µm. The wavelength selective thermal radiation material according to claim 3, wherein a period of the microcavity is 4 to 7 μm. The wavelength selective thermal radiation material according to any one of claims 3 to 8 , wherein an opening ratio of the microcavity is in a range of 0.5 to 0.9. The wavelength-selective heat radiation material according to any one of claims 3 to 9 , wherein an aspect ratio of the microcavity is in a range of 0.8 to 3.0. 4. The wavelength-selective heat radiation material according to claim 3, which is used to improve heat dissipation efficiency of the heat source in an electronic device in which the heat source is covered with a resin member having a specific infrared transmission wavelength region. A way to
(A) opening a large number of periodically arranged holes opened in the metal thin film sheet using a photolithography process, thereby obtaining a porous metal mask;
(B) A resist is applied to a semiconductor substrate, the porous metal mask is disposed so as to face the resist coating film, and pattern exposure is performed by irradiating the resist coating film with light having a predetermined wavelength through the periodic array holes. Steps,
(C) contacting the resist coating film with a developer, and developing a pattern exposure latent image in the resist coating film;
(D) pattern-etching the semiconductor substrate using a predetermined etching method, thereby forming a fine concavo-convex pattern on the surface of the semiconductor substrate; and (e) removing the resist coating film from the semiconductor substrate. A metal coating film is laminated on the fine concavo-convex pattern on the surface of the semiconductor substrate using a physical vapor deposition method or a chemical vapor deposition method, thereby periodically two-dimensionally arranging the semiconductor substrate on the semiconductor substrate. Obtaining a modified microcavity;
A method for producing a wavelength-selective thermal radiation material, comprising: In the step (a), the periodic array holes of the porous metal mask are formed to have substantially the same period as the wavelength of the infrared transmission wavelength region of the resin member covering the heat source or a period shorter by 1 μm. The method for producing a wavelength-selective heat radiation material according to claim 11 .