JP2021184411A - Heat dissipation member - Google Patents

Abstract

To provide a heat dissipation member that suppress the effects of heat and dissipate heat effectively even when a heat-generating component that is about to dissipate heat is placed in an environment that receives heat.MEANS: A heat dissipation member according to the present invention that dissipates heat from a heat-generating component includes a base material composed of a base portion that adheres to the heat-generating component and a fine concavo-convex structure portion that selectively radiates predetermined infrared rays, and a resin layer that covers the fine concavo-convex structure and transmits the predetermined infrared rays, and the resin layer contains a group of particles having a lower apparent density than the resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for a heat radiating member that dissipates heat from a heat-generating component, and more particularly to a heat-dissipating member that effectively dissipates heat even in an environment where another heating element is present in the vicinity of the heat-generating component.

In recent years, the performance and miniaturization of electronic devices including electronic parts and module parts have been progressing. Higher performance leads to an increase in heat generation of electronic parts and module parts, and miniaturization leads to high-density mounting of electronic parts and module parts, so the heat generation amount (heat generation density) per unit area of electronic devices tends to increase. be.

The increase in heat generation density induces the generation of heat spots in which heat is locally concentrated in the electronic device, which causes a failure of the electronic device (for example, a decrease in operational stability and a decrease in reliability). Therefore, it is important to effectively dissipate the heat generated in the electronic parts and the module parts to suppress the generation of heat spots.

As a heat dissipation measure for electronic parts and module parts, heat dissipation members such as metal plates and heat sinks have been conventionally attached near the heat generation parts of electronic parts and module parts, and the heat generated in the heat generation parts is thermally conducted to the heat dissipation members, such as air. It has been carried out to dissipate heat by transferring heat to the refrigerant of. On the other hand, a technique using heat radiation has been developed to realize more efficient heat dissipation.

For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-304200), a circuit board on which an electronic component including a heat-generating element is mounted, a cover made of a metal material for holding the circuit board, and a combination of the cover. An electronic control device for engine control including a case made of a metal material for accommodating the circuit board, and the outer and inner surfaces of the case have a black surface treatment for increasing the infrared absorption rate. A heat conductive member which is formed and conducts heat of an electronic component mounted on the circuit board to the cover is provided, and a contact portion of the cover in surface contact with the heat conductive member is used to enhance heat conduction. An electronic control device for engine control, characterized in that it has a metal surface that is not surface-treated, is disclosed.

Patent Document 2 (Japanese Patent Laid-Open No. 2010-027831) describes a large number of microcavities that form a periodic surface fine uneven pattern in an electronic device whose heat generation source is covered with a resin member having a specific infrared transmission wavelength range. A wavelength-selective heat-radiating material having a two-dimensionally arranged heat-radiating surface is arranged between the heat-generating source and the resin member so as to cover the heat-generating source, and heat energy from the heat-generating source is transferred or transferred. It is input to the wavelength-selective heat-radiating material by heat radiation, and the heat-radiated light corresponding to the infrared transmission wavelength range of the resin member is selected from the heat-radiating surface of the wavelength-selective heat-radiating material toward the resin member. Disclosed is a method of improving the heat dissipation efficiency of the electronic device by radiating the heat.

Japanese Unexamined Patent Publication No. 2004-304200 Japanese Patent No. 2010-027831

According to Patent Document 1, the heat-generating electronic component mounted on the circuit board can increase the amount of heat transferred to the accommodating member by radiant heat by the surface state that increases the infrared absorption rate of the inner surface of the cover or the case. It is said that it is possible to reduce the heat generation temperature.

Further, according to Patent Document 2, by applying a wavelength-selective thermal radiation material having a thermal radiation surface in which a large number of microcavities forming a periodic surface fine unevenness pattern are two-dimensionally arranged, the heat dissipation efficiency of an electronic device can be improved. As a result, it is said that an electronic device having a heat generating source can be sufficiently radiated and cooled without using a special device such as a cooling fan.

Recently, the miniaturization of electronic devices has been progressing more and more, and heat-generating components may be arranged close to each other. In that case, there is a concern that heat transfer from one heat-generating component (hereinafter referred to as heat transfer) may hinder heat dissipation from the other heat-generating component. In other words, there is a need for technology that can effectively dissipate heat even in an environment where heat is generated. On the other hand, in Patent Documents 1 and 2, unfortunately, no particular consideration or thought regarding fever is made.

The present invention has been made in view of the above-mentioned problems, and is affected by heat generation even in an environment in which another heating element exists in the vicinity of a heat-generating component to dissipate heat (environment in which heat generation is generated). It is an object of the present invention to provide a heat radiating member capable of effectively dissipating heat by suppressing the above.

One aspect of the present invention is a heat radiating member that dissipates heat from heat-generating components.
A base material composed of a base portion that adheres to the heat-generating component and a fine concavo-convex structure portion that selectively radiates predetermined infrared rays.
It covers the fine concavo-convex structure and is provided with a resin layer that transmits the predetermined infrared rays.
The resin layer provides a heat radiating member, characterized in that it contains a group of particles having a lower apparent density than the resin.

According to the present invention, it is possible to provide a heat radiating member that effectively dissipates heat by suppressing the influence of the receiving heat even if the heat generating component to be radiated is placed in an environment receiving heat.

It is sectional drawing which shows an example of the heat dissipation member which concerns on this invention. It is a schematic diagram which shows the experimental environment.

The present invention can make the following improvements and changes to the heat dissipation member described above.
(I) The fine concavo-convex structure portion is made of a metallic material, and the group of particles having a low apparent density includes at least one of hollow particles and porous particles.
(Ii) The group of particles having a low apparent density is contained in an amount of 3% by volume or more and 30% by volume or less with respect to the resin layer.
(Iii) The group of particles having a low apparent density has an average particle size of 1 μm or more and 200 μm or less.
(Iv) The thickness of the resin layer is 1 μm or more and 300 μm or less.
(V) The group of particles having a low apparent density is unevenly distributed in the surface region of the resin layer.

Hereinafter, embodiments according to the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the embodiments taken up here, and can be appropriately combined with a known technique or improved based on the known technique without departing from the technical idea of the invention. .. Further, the same reference numerals may be given to members having the same meaning, and duplicate description may be omitted.

FIG. 1 is a schematic cross-sectional view showing an example of a heat radiating member according to the present invention. As shown in FIG. 1, the heat radiating member 100 is a member for radiating the heat of the heat generating component 1, and has fine irregularities that selectively radiate a predetermined infrared ray and a base portion 11 adhering to the heat generating component 1. A base material 10 composed of a structural portion 12 and a resin layer 20 that covers the fine concavo-convex structural portion 12 and transmits the infrared rays are provided, and the resin layer 20 has particles 22 having an apparent density lower than that of the resin 21 (hereinafter, low). It contains a group of (abbreviated as density particles).

Since the heat radiating member 100 of the present invention has a fine concavo-convex structure portion 12 that selectively radiates predetermined infrared rays and a resin layer 20 that covers the fine concavo-convex structure portion 12 and transmits the infrared rays, the heat-generating component 1 Heat can be effectively dissipated. Further, since the group of the low-density particles 22 contained in the resin layer 20 has lower thermal conductivity than the resin 21 of the resin layer 20, the heat generated by the resin layer 20 becomes the heat-generating component 1 even in a heat environment. It can suppress conduction.

Each configuration of the heat radiating member 100 will be described in more detail.

As described above, the base material 10 is composed of the base portion 11 and the fine concavo-convex structure portion 12, but the base portion 11 and the fine concavo-convex structure portion 12 may be made of the same material or may be made of different materials. It may have been done. The thickness of the base material 10 is not particularly limited and can be appropriately selected in the range of, for example, 0.01 mm or more and 3 mm or less.

The base portion 11 is a metal material or ceramic having good thermal conductivity (for example, thermal conductivity of 100 W / m · K or more) so that the heat from the heat-generating component 1 can be easily transferred to the fine concavo-convex structure portion 12. It is preferably made of a material. For example, aluminum (Al), Al alloy, copper (Cu), Cu alloy, silicon carbide (SiC), aluminum nitride (AlN) and the like can be preferably used.

The fine concavo-convex structure portion 12 is preferably made of a metal material having ^{good conductivity (for example, an electrical resistivity of less than 1 × 10 -7} Ωm at room temperature) in order to efficiently generate surface plasmon resonance. For example, Al, Al alloy, Cu, Cu alloy, silver (Ag), gold (Au), nickel (Ni), cobalt (Co) and the like can be preferably used.

Further, the fine concavo-convex structure portion 12 is preferably formed so that the wavelength at which the surface plasmon resonance is maximum (the wavelength at which the absorption rate is maximum, also referred to as the peak wavelength) is infrared rays in the range of 1 μm or more and 8 μm or less. , It is more preferable that the infrared rays are formed in the range of 1 μm or more and 6 μm or less. Specifically, it is preferable that the in-plane pitch of the uneven structure is controlled within the range of 0.5 μm or more and 10 μm or less, and the gap in the thickness direction of the uneven structure is controlled within the range of 0.25 μm or more and 10 μm or less. ..

The method for forming the fine concavo-convex structure portion 12 is not particularly limited as long as a desired structure can be obtained, and conventional methods (for example, photolithography method, vapor deposition method, plating method, etc.) can be appropriately used. For example, when the base portion 11 and the fine concavo-convex structure portion 12 are made of the same material, the fine concavo-convex structure portion 12 may be formed directly on one main surface of the base portion 11. When the base portion 11 and the fine concavo-convex structure portion 12 are made of different materials, after forming a layer made of a metal material having good conductivity on one main surface of the base portion 11, fine particles are formed on the metal layer. The uneven structure portion 12 may be formed.

Further, if the surface of the heat-generating component 1 to be dissipated is made of a metal material having good conductivity and processing of the surface of the heat-generating component 1 is permitted, the surface of the heat-generating component 1 is directly applied to the surface of the heat-generating component 1. The fine concavo-convex structure portion 12 may be formed.

As the resin 21 of the resin layer 20 that covers the fine concavo-convex structure portion 12, if the resin has a high transmission rate of infrared rays (particularly infrared rays having a peak wavelength) emitted from the fine concavo-convex structure portion 12, it is a thermosetting resin or a thermoplastic. A resin or an ultraviolet curable resin can be used as appropriate. In the present invention, the high infrared transmittance means that the band having a wavelength of 1 μm or more and 8 μm or less includes a band having a transmittance of 50% or more.

Specifically, as the resin 21, phenol resin, alkyd resin, aminoalkido resin, urea resin, silicon resin, melamine urea resin, epoxy resin, polyurethane resin, vinyl acetate resin, acrylic resin, rubber chloride resin, vinyl chloride resin, A fluororesin or the like can be preferably used.

The thickness of the resin layer 20 is preferably 1 μm or more and 300 μm or less, more preferably 5 μm or more and 200 μm or less, and further preferably 10 μm or more and 150 μm or less. If the thickness of the resin layer 20 is less than 1 μm, the heat insulating effect of the group of low-density particles 22 cannot be sufficiently exhibited. On the other hand, when the thickness of the resin layer 20 exceeds 300 μm, the heat retaining action of the resin layer 20 becomes stronger and the heat dissipation property deteriorates.

As the low-density particles 22 contained in the resin layer 20, it is preferable to use hollow particles and / or porous particles in order to have lower thermal conductivity than the resin 21. In other words, since the hollow particles and the porous particles have a high porosity / porosity in the particles, the thermal conductivity can be made lower than that of the solid resin material. The material of the low-density particles 22 is not particularly limited as long as the transmittance of infrared rays is high, and oxides (for example, silica, alumina, glass, etc.) and organic substances (for example, phenol resin, epoxy resin, urea resin, etc.) are appropriately used. Available.

The average particle size of the low-density particles 22 is preferably 1 μm or more and 200 μm or less, more preferably 2 μm or more and 150 μm or less, and further preferably 5 μm or more and 100 μm or less. When the average particle size of the low-density particles 22 is less than 1 μm, the porosity / porosity in the particles decreases, so that the effect of reducing the thermal conductivity becomes insufficient. On the other hand, when the average particle size of the low-density particles 22 exceeds 200 μm, the low-density particles 22 tend to fall off from the resin layer 20 and the effect of lowering the thermal conductivity becomes insufficient.

The mixing ratio of the low-density particles 22 in the resin layer 20 is preferably 3% by volume or more and 30% by volume or less, more preferably 4% by volume or more and 25% by volume or less, and 5% by volume or more and 20% by volume or less with respect to the resin 21. More preferred. When the mixing ratio of the low-density particles 22 is less than 3% by volume, the effect of lowering the thermal conductivity becomes insufficient. On the other hand, when the mixing ratio of the low-density particles 22 exceeds 30% by volume, it becomes difficult to form the resin layer 20.

From the viewpoint of the effect of lowering the thermal conductivity, the group of the low-density particles 22 preferably uniformly covers the base material 10 when the resin layer 20 is projected / seen through in the thickness direction. Further, the resin layer 20 may be evenly dispersed in the resin layer 20 when viewed in the in-plane direction (direction orthogonal to the thickness direction), but is unevenly distributed in the surface region of the resin layer 20. Is more preferable.

The method for forming the resin layer 20 is not particularly limited as long as a desired structure can be obtained, and the conventional method can be appropriately used. For example, a method of applying a resin / particle paint in which a resin 21 and a low-density particle 22 are mixed to a base material 10, a method of attaching a resin sheet in which a low-density particle 22 is mixed to a base material 10, and a method of using a resin paint as a base material. A method of embedding low-density particles 22 after the resin paint is applied to 10 and before the resin paint is cured can be appropriately used.

When preparing a paint or a resin sheet for forming a resin layer, a solvent, a film-forming auxiliary, a plasticizer, a pigment, a silane coupling material, a viscosity modifier, or the like may be added or mixed as needed.

Hereinafter, the present invention will be described in more detail by various experiments. However, the present invention is not limited to the configurations and structures described in these experiments.

[Experiment 1]
(Preparation of Example 1)
Fine concavo-convex structure 12 (cylindrical recess: diameter 2 μm × depth 2 μm, using photolithography) on one main surface of Al plate (JIS A1100, length 30 mm × width 30 mm × thickness 1 mm) The base material 10 was prepared by forming an in-plane pitch of the columnar recess (4.2 μm).

On the other hand, hollow glass particles (manufactured by 3M Co., Ltd., Glass Bubbles, S42XHS, apparent density) are opposed to acrylic resin (manufactured by Toray Fine Chemical Co., Ltd., Coatax (registered trademark), LH series, density 1.1 g / cm ^3). (0.42 g / cm ³ , average particle diameter 22 μm) is mixed so as to be 5% by volume, and 30 parts by mass of butyl acetate as a solvent is mixed with 100 parts by mass of the mixed material to form a resin / particle for forming a resin layer. The paint was mixed.

Next, the resin / particle paint is spray-painted using a spray-coating device so as to cover the fine uneven structure portion 12 of the base material 10, and then the coating film is dried to dry the heat-dissipating member (resin layer 20 of the resin layer 20) of Example 1. A thickness of 100 μm) was prepared.

Next, in order to investigate the heat dissipation characteristics / heat insulation characteristics of the heat dissipation member, a planar heating element (manufactured by Shinwa Rules Co., Ltd., polyimide heater, FL heater 04_PI_20Ω, length 30 mm x width 30 mm) is used as a pseudo heating element. Was prepared, and the base portion 11 of the heat radiating member was attached to one main surface of the planar heating element. At this time, a K thermocouple for temperature measurement was sandwiched between the base portion 11 and the planar heating element. Further, on the other main surface of the planar heating element, a flat plate Al plate (JIS A1100, length 30 mm × width 30 mm × thickness 1 mm) on which the fine concavo-convex structure portion 12 was not formed was attached. From the above, the test sample of Example 1 was prepared.

When the cross section of the heat radiating member of Example 1 separately prepared for tissue observation was observed, it was confirmed that the heat radiating member had a structure corresponding to FIG. Since the apparent density of the low-density particles 22 was sufficiently smaller than the density of the resin 21, it was considered that the low-density particles floated up during the drying process of the coating film and were unevenly distributed in the surface region of the resin layer 20.

In addition, the difference in infrared absorption depending on the presence or absence of the formation of the fine concavo-convex structure portion 12 was measured by a Fourier transform infrared spectrophotometer. As a result, the integrated infrared absorption spectrum in the wavelength range of 1 to 8 μm in the fine concavo-convex structure portion 12 was 0.6 or more with respect to the integrated infrared absorption spectrum in the wavelength range of 1 to 20 μm. On the other hand, in the Al plate on which the fine concavo-convex structure portion 12 was not formed, the absorption spectrum of infrared rays having a wavelength of 1 to 8 μm was not substantially observed.

(Preparation of Example 2)
The low-density particles 22 of the resin / particle paint used in Example 1 were added to a 5% by volume silas balloon (Axies Chemical Co., Ltd., Winlight, MSB-3011S, apparent density 0.5 g / cm ³ , average particle diameter 30 μm). The heat radiating member and the test sample of Example 2 were prepared in the same manner as in Example 1 except that they were changed.

(Preparation of Example 3)
The heat dissipation member and the test sample of Example 3 were prepared in the same manner as in Example 1 except that the low density particles 22 of the resin / particle paint used in Example 1 were changed to 8% by volume hollow glass particles. ..

(Preparation of Example 4)
The low-density particles 22 of the resin / particle paint used in Example 1 were changed to 5% by volume hollow polymer particles (Sekisui Chemical Co., Ltd., Advancel, EML101, apparent density 0.02 g / cm ³ , average particle diameter 15 μm). Except for the above, the heat radiating member and the test sample of Example 4 were prepared in the same manner as in Example 1.

(Preparation of Comparative Example 1)
A resin paint was prepared in the same manner as in Example 1 except that the low-density particles 22 were not mixed. Next, a flat plate Al plate (JIS A1100, length 30 mm x width 30 mm x thickness 1 mm) on which the fine concavo-convex structure portion 12 is not formed is used as the base material 10, and one of the main surfaces is covered. After spray-coating the resin paint using a spray-coating device, the coating film was dried to prepare a heat-dissipating member (thickness 100 μm of the resin layer 20) of Comparative Example 1.

Then, a test sample of Comparative Example 1 was prepared in the same manner as in Example 1. Comparative Example 1 is a comparative sample in which the influence of the fact that the fine concavo-convex structure portion 12 is not formed on the base material 10 can be observed.

(Preparation of Comparative Example 2)
The heat dissipation member of Comparative Example 2 is the same as that of Comparative Example 1 except that the base material 10 used in Comparative Example 1 is changed to the same base material as that of Example 1 (a base material on which the fine concavo-convex structure portion 12 is formed). And a test sample were prepared. Comparative Example 2 is a comparative sample in which the influence of the resin layer 20 not containing the low-density particles 22 can be observed.

(Preparation of other heat-generating parts)
A flat plate Al plate (JIS A1100, length 30 mm × width 30 mm × thickness 1 mm) was attached to both main surfaces of a planar heating element similar to that in Example 1. At this time, a K thermocouple for temperature measurement was sandwiched between the Al plate and the planar heating element. As a result, we prepared other heat-generating parts to build a thermal environment.

[Experiment 2]
(Heat dissipation test in an environment without heat)
FIG. 2 is a schematic diagram showing an experimental environment. As shown in FIG. 2, other heat-generating components are placed 2 cm apart so as to face the heat-dissipating member of the test sample, and they are placed in a closed container (temperature at the start of the experiment, 25 ° C.) to prevent the influence of wind. ). The experimental environment in FIG. 2 was the same for Experiments 2 to 4.

In Experiment 2, the temperature of the test sample was measured by applying a constant power (5 W) only to the planar heating element of the test sample. Since a constant power is applied to the planar heating element, the measured temperature stabilizes when it is balanced with the amount of heat released. That is, it is expected that the test sample having higher heat dissipation shows a lower temperature. The results are shown in Table 1.

As shown in Table 1, looking at Comparative Examples 1 and 2, it can be seen that Comparative Example 2 is about 10 ° C. lower. From this, it is confirmed that the heat dissipation is improved by forming the fine concavo-convex structure portion 12 on the base material 10. Further, the temperatures of Examples 1 to 4 are equivalent to the temperatures of Comparative Example 2. From this, it is confirmed that the group of the low-density particles 22 contained in the resin layer 20 does not impair the heat dissipation.

[Experiment 3]
(Insulation test in a thermal environment)
In Experiment 3, constant power (4.5 W) was applied only to the planar heating element of other heating components, and the temperatures of the other heating components and the test sample were measured. In Experiment 3, it is expected that the test sample with higher heat insulation shows a lower temperature. The results are shown in Table 2.

As shown in Table 2, the temperatures of the other heat-generating components are the same in all of Comparative Examples 1 and 2 and Examples 1 to 4. That is, the conditions of heat reception can be regarded as equivalent for all test samples. Looking at Comparative Examples 1 and 2, it can be seen that Comparative Example 2 is about 5 ° C. lower. It is considered that this is because the fine concavo-convex structure portion 12 of the base material 10 receives and dissipates heat again. Further, it can be seen that the temperatures of Examples 1 to 4 are lower than the temperature of Comparative Example 2 by 5 ° C. or more. From this, it is confirmed that the group of the low-density particles 22 contained in the resin layer 20 enhances the heat insulating property in the heat environment.

[Experiment 4]
(Heat dissipation and heat insulation test in a thermal environment)
In Experiment 4, a constant power (4.5 W) was applied to the planar heating element of the other heat-generating component, and a constant power (2.5 W) was applied to the planar heating element of the test sample to apply the constant power (2.5 W) to the other heat-generating component and the planar heating element. The temperature of the test sample was measured. In Experiment 4, it is expected that the test sample with higher heat insulation shows a lower temperature. The results are shown in Table 3.

As shown in Table 3, the temperatures of the other heat-generating components are the same in all of Comparative Examples 1 and 2 and Examples 1 to 4. That is, the conditions of heat reception can be regarded as equivalent for all test samples. Looking at Comparative Examples 1 and 2, it can be seen that Comparative Example 2 is about 7 ° C. lower. It is considered that this is because the fine concavo-convex structure portion 12 of the base material 10 receives and dissipates heat again. Further, it can be seen that the temperatures of Examples 1 to 4 are lower than the temperature of Comparative Example 2 by 8 ° C. or more. From this, it is confirmed that the group of the low-density particles 22 contained in the resin layer 20 enhances the heat insulating property in the heat environment.

From the results of the above experiments 2 to 4, the heat radiating member according to the present invention suppresses the influence of the heat received and effectively dissipates heat even if the heat generating component to be radiated is placed in an environment where it receives heat. It was confirmed that it can be done.

The above-described embodiments and experimental examples have been described for the purpose of assisting the understanding of the present invention, and the present invention is not limited to the specific configuration described. For example, it is possible to replace a part of the configuration of the embodiment with the configuration of the common general technical knowledge of those skilled in the art, and it is also possible to add the configuration of the common general technical knowledge of those skilled in the art to the configuration of the embodiment. That is, the present invention may delete, replace with another configuration, or add another configuration to a part of the configurations of the embodiments and experimental examples of the present specification without departing from the technical idea of the invention. It is possible.

1 ... heat-generating parts, 10 ... base material, 11 ... base part, 12 ... fine uneven structure part,
20 ... resin layer, 21 ... resin, 22 ... low density particles, 100 ... heat dissipation member.

Claims (6)

It is a heat dissipation member that dissipates heat from heat-generating parts.
A base material composed of a base portion that adheres to the heat-generating component and a fine concavo-convex structure portion that selectively radiates predetermined infrared rays.
It covers the fine concavo-convex structure portion and is provided with a resin layer that transmits the predetermined infrared rays.
The resin layer is a heat radiating member containing a group of particles having a lower apparent density than the resin. In the heat dissipation member according to claim 1,
The fine concavo-convex structure is made of a metal material and is made of a metal material.
The heat-dissipating member, wherein the group of particles having a low apparent density contains at least one of hollow particles and porous particles. In the heat radiating member according to claim 1 or 2.
The heat-dissipating member, wherein the group of particles having a low apparent density is contained in an amount of 3% by volume or more and 30% by volume or less with respect to the resin layer. The heat radiating member according to any one of claims 1 to 3.
The group of particles having a low apparent density is a heat dissipation member having an average particle diameter of 1 μm or more and 200 μm or less. In the heat radiating member according to any one of claims 1 to 4.
The resin layer is a heat radiating member having a thickness of 1 μm or more and 300 μm or less. In the heat radiating member according to any one of claims 1 to 5.
The heat-dissipating member, characterized in that the group of particles having a low apparent density is unevenly distributed in the surface region of the resin layer.

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