WO2010101188A1

WO2010101188A1 - Resin-coated metallic material with excellent planar-direction thermal conductivity

Info

Publication number: WO2010101188A1
Application number: PCT/JP2010/053449
Authority: WO
Inventors: 岳志児嶋; 平野　康雄; 五十嵐　哲也
Original assignee: 株式会社神戸製鋼所
Priority date: 2009-03-04
Filing date: 2010-03-03
Publication date: 2010-09-10
Also published as: TWI430881B; MY161391A; KR101316981B1; JP2010228449A; CN102333646B; CN102333646A; KR20110111526A; JP5337742B2; TW201043456A

Abstract

A resin-coated metallic material comprising a metallic base, at least one surface of which has been coated with a resinous coating film containing thermally conductive particles. When a photograph of a planar-direction section of the resinous coating film taken with a scanning electron microscope is subjected to image analysis, the thermally conductive particles observed in the field of view satisfy the following requirements (1) to (3). (1) The thermally conductive particles have an aspect ratio, which is the value obtained by dividing the maximum length by the minimum length of the particles (maximum length/minimum length), of 3.0 or higher on average, (2) when the thermally conductive particles are examined for the angle of inclination of the longest axis with the planar-direction horizontal line, the frequency of thermally conductive particles having an angle of inclination of 0º or larger but less than 30º is 40% or higher, and (3) the areal proportion of the thermally conductive particles is 30% or higher.

Description

Resin-coated metal material with excellent surface direction thermal conductivity

The present invention relates to a resin-coated metal material having excellent surface direction heat conductivity, and in particular, an electronic device in which a heat source is in local contact with the metal material and high heat conductivity in the surface direction is strongly required. The present invention relates to a resin-coated metal material suitably used as a material for parts (including electrical equipment parts and optical equipment parts). Examples of such electronic equipment components include a heat sink, a back chassis such as a thin television, and a metal casing (casing) that houses an electronic equipment component incorporating a heat source.

As the performance and miniaturization of electronic devices and the like progress, research on heat dissipating members that dissipate the heat generated from the heat sources inside the electronic devices is actively conducted. Of these, heat dissipation members that are in local contact with heat sources, such as the back chassis of flat-screen televisions, can quickly diffuse the generated heat over a large area, that is, the thermal conductivity in the surface direction of the heat dissipation member. It is required to be excellent. If the thermal conductivity in the plane direction is low, a temperature gradient is generated in the plane direction, causing in-plane temperature dispersion, resulting in defects such as color irregularities on the light emitting surface and cracks in the glass substrate. .

In particular, when the heat dissipating member is made of a metal material such as a steel plate and the heat source is in contact with the metal material, the heat conductivity in the surface direction can be increased instead of the heat conductivity in the thickness direction of the metal material. Very important. When the heat source is in contact with a heat radiating member such as a steel plate, the heat transfer path from the heat source to the steel plate and the outside can be considered in two directions: the thickness direction and the surface direction. The heat transfer distance in the thickness direction is short, so the effect of increasing the heat transfer amount due to the improvement in the heat conductivity in the thickness direction is very small, whereas the heat transfer area in the surface direction is very wide, so the heat conductivity in the surface direction is This is because a dramatic increase in the amount of heat transfer due to can be expected.

However, much research on the heat dissipation member focuses on improving the thermal conductivity in the thickness direction of the heat dissipation member, from the viewpoint of quickly diffusing heat from the electronic device part incorporating the heat source to the outside. The fact is that the thermal conductivity in the surface direction of the heat dissipating member has not been paid much attention. For example, Patent Document 1 discloses a metal material having a coating layer containing minute carbon fibers (typically carbon nanotubes) having an average aspect ratio of 3 or more as a material that can efficiently absorb and dissipate heat. However, it is considered that only the thermal conductivity in the thickness direction is evaluated in consideration of the measurement method of thermal conductivity.

JP 2005-199666 A

The present invention has been made by paying attention to the above circumstances, and an object thereof is to provide a resin-coated metal material having excellent surface direction thermal conductivity.

The resin-coated metal material of the present invention is a resin-coated metal material in which at least one surface of a metal substrate is coated with a resin film containing thermally conductive particles, and image analysis is performed on a scanning electron micrograph of a cross section in the plane direction of the resin film. Then, the heat conductive particles observed in the measurement visual field satisfy the following requirements (1) to (3).
(1) The average value of the oblateness represented by the value obtained by dividing the maximum length of the heat conducting particles by the minimum length (maximum length / minimum length) is 3.0 or more,
(2) When the inclination angle between the maximum length of the heat conducting particles and the horizontal line in the plane direction is measured, the frequency ratio of the heat conducting particles existing in the range where the inclination angle is 0 ° or more and less than 30 ° is 40% or more. ,
(3) The area ratio of the heat conductive particles is 30% or more.

In a preferred embodiment of the present invention, the resin film has a surface direction thermal conductivity of 1.5 W / mK or more.

In a preferred embodiment of the present invention, the thermally conductive particles are copper, aluminum, or graphite.

In a preferred embodiment of the present invention, the resin-coated metal material is used for electronic equipment parts.

The present invention includes electronic device parts having the above resin-coated metal material within the scope of the present invention.

Since the present invention is configured as described above, a resin-coated metal material having high thermal conductivity in the surface direction could be provided. By using the metal material of the present invention, it is possible to prevent a decrease in temperature gradient caused by a heat source in contact with the metal material. Therefore, a heat sink or a back chassis such as a thin TV that is particularly required to have high thermal conductivity in the surface direction. It is suitably used as a material for electronic device parts.

FIG. 1 is a diagram schematically showing thermally conductive particles in a resin film. FIG. 9 is an inclination angle number distribution graph of 9 (example of the present invention). 3 shows No. 1 of Example 1. It is a photograph which shows the SEM image and image analysis result of 9 (invention example). 4 shows No. 1 of Example 1. It is a photograph which shows the SEM image of 11 (comparative example), and an image analysis result. FIG. 14 is a photograph showing SEM images of 14 and 16 (examples of the present invention) and image analysis results. 6A shows No. 1 of Example 1. FIG. 2 is a photograph showing SEM images and image analysis results of 2 to 5 (comparative examples). 6B shows No. 1 of Example 1. FIG. 6 is a photograph showing SEM images of 6 to 8 (comparative examples) and image analysis results. FIG. 7 is a schematic diagram for explaining the configuration of the measurement apparatus for the planar thermal conductivity used in the present invention. FIG. It is an inclination angle number distribution graph of 9, 14, and 16 (invention example). 9A shows No. 1 of Example 1. FIG. 6 is an inclination angle number distribution graph of 2 to 6 (comparative example). 9B shows No. 1 of Example 1. It is an inclination angle number distribution graph of 7, 8, and 11 (comparative example). 10A shows No. 1 of Example 1. FIG. It is a photograph which shows the SEM image and image analysis apparatus of 9, 10, 12, 15 (invention example). 10B shows No. 1 of Example 1. FIG. It is a photograph which shows the SEM image of 17, 19, and 20 (example of this invention) and an image-analysis apparatus. 11 shows No. 1 of Example 1. It is a photograph which shows the SEM image of 18 (comparative example), and an image analyzer. 12A shows No. 1 of Example 1. FIG. It is an inclination angle number distribution graph of 9, 10, and 12 (example of this invention). 12B shows No. 1 of Example 1. FIG. 15 is an inclination angle number distribution graph of 15 and 17 (examples of the present invention). 12C shows No. 1 of Example 1. FIG. 19 is an inclination angle number distribution graph of 19 and 20 (examples of the present invention). 13 shows No. 1 of Example 1. 18 is a graph showing the number of inclination angles distributed in 18 (comparative example).

Among the heat radiating members for electronic devices, the present inventors are particularly suitable as a material for a heat radiating member in which a heat source is locally in contact with the heat radiating member and high thermal conductivity in the surface direction is strongly required. In order to provide resin-coated metal materials, investigations have been repeated. As a result, the desired high surface direction thermal conductivity cannot be obtained by simply adding a large amount of high thermal conductivity particles having high thermal conductivity into the resin film (see, for example, Nos. 3 and 4 in Table 2). In the resin film, the shape and direction of the heat conduction particles (the degree of inclination of the particles with respect to the horizontal line in the plane direction, defined by the “inclination angle”) are appropriately controlled. As a result, the present invention was completed.

That is, the resin-coated metal material of the present invention is a resin in which a resin film containing heat conductive particles is coated on at least one surface (heat source side) of a metal substrate, and a scanning electron micrograph of a cross section in the plane direction of the resin film. When the (SEM photograph) is subjected to image analysis, the heat conductive particles observed in the measurement visual field satisfy the following requirements (1) to (3).
(1) The average value of the oblateness represented by the value obtained by dividing the maximum length of the heat conducting particles by the minimum length (maximum length / minimum length) is 3.0 or more,
(2) When the inclination angle between the maximum length of the heat conducting particles and the horizontal line in the plane direction is measured, the frequency ratio of the heat conducting particles existing in the range where the inclination angle is 0 ° or more and less than 30 ° is 40% or more. ,
(3) The area ratio of the heat conductive particles is 30% or more.

Thus, the characteristic part of the present invention is that the above requirements (1) to (3) are defined as requirements that greatly contribute to the improvement of the thermal conductivity in the plane direction. As demonstrated in the examples described later, in the present invention, it is necessary to satisfy all of the above three requirements. If any one of the requirements does not satisfy the present invention, desired characteristics cannot be obtained.

First, the flatness defined in the above (1) and the inclination angle defined in the above (2) will be described in detail with reference to FIG. FIG. 1 is a diagram schematically showing thermally conductive particles obtained by an image analysis means described in detail later.

The flatness defined in (1) above is calculated by the ratio (maximum length / minimum length) between the maximum length shown in FIG. 1 and the minimum length calculated based on the maximum length. The minimum length is the length when the width of the parallel line is the minimum when the heat conducting particles are sandwiched between two straight lines parallel to the maximum length. In the present invention, a value obtained by dividing the maximum length by the minimum length is defined as “the flatness of the heat conducting particles”.

The inclination angle (direction) defined in (2) above is the angle formed between the horizontal line in the surface direction and the line that extends the maximum length and intersects the horizontal line as shown in FIG. Here, the angle formed with the horizontal line in the surface direction means an angle with respect to a direction parallel to the surface of the resin film in a plane perpendicular to the surface of the resin film. Next, according to the analysis procedure described later, the number of thermal conductive particles (degrees) existing in the range of the tilt angle of 0 to 180 ° is measured every 10 °, and the tilt angle number distribution graph is created. For reference, No. 1 in Table 1 of Examples described later is used. The upper graph of FIG. The horizontal axis of FIG. 2 plots the inclination angle (10 °, 20 °, up to 180 °), and the heat conduction existing at 0 ° to less than 10 °, 10 ° to less than 20 °, etc. for each inclination angle. The frequency (number) of particles is shown as a bar graph. In the present invention, the results of the inclination angle of 0 ° or more and less than 10 ° and more than 170 ° and 180 ° or less are considered to be equivalent because of the relationship of the enantiomer, so that the heat conductive particles existing in the respective inclination angle ranges. Add the frequencies. When dividing the entire inclination angle range (0 to 180 °) every 10 °, as shown in the above example, 0 ° or more and less than 90 ° shall be “more than or less than” and from 90 ° to 180 ° or less. Is “super, below”. Note that only 90 ° is included in the region of “80 ° or more and less than 90 °” or “over 90 ° and 100 ° or less”. As a result, the frequencies of all the particles existing within the inclination angle range of 0 to 180 ° can be expressed as the frequencies of the particles existing within the inclination angle range of 0 to 90 °.

The lower diagram of FIG. 2 is an arrangement of the tilt angle number distribution graph (tilt angle 0 to 180 °) shown in the upper diagram of FIG. 2 as described above, and exists within the range of the tilt angle 0 to 90 °. The frequency of the heat conductive particles is shown in units of 10 °. In the present invention, based on the slope angle distribution graph shown in the lower part of FIG. 2 obtained as described above, the sum of the frequencies existing in the range of the tilt angle of 0 to 30 ° is set within the range of the tilt angle of 0 to 90 °. The value divided by the entire frequency (total frequency) existing in is defined as “frequency ratio of thermally conductive particles existing in a range where the inclination angle is 0 ° or more and less than 30 °”.

Next, the usefulness of the present invention will be described in detail with reference to FIG. 3 and FIG. Among these, FIG. 3 shows No. 1 of Example 1 that satisfies all the requirements (1) to (3). 9 is a photograph showing the SEM image of Example 9 (example of the present invention) and the image analysis result, and FIG. 11 (comparative example).

As shown in FIG. 3, in the example of the present invention, a large number of particles having a predetermined flat shape and having a predetermined inclination angle are present substantially continuously in the plane direction while being appropriately overlapped. As a result, it is considered that a heat path (path) is formed in the surface direction and the surface direction thermal conductivity is increased. For reference, the direction of heat flow is indicated by → in the image analysis result of FIG.

On the other hand, in the comparative example, as shown in FIG. 4, there are many hollow portions where no particles exist in the plane direction. Therefore, it is considered that the heat path in the surface direction is divided and the surface direction thermal conductivity is lowered.

For reference, the results of Example 1 other than the above are shown in FIG. 5, FIG. 6A, FIG. 6B, FIG. 10A to FIG. Among these, FIG. 5, FIG. 10A and FIG. 10B show No. 1 of Example 1 which satisfies all the requirements (1) to (3). 9, 10, 12, 14, 15, 16, 17, 19, and 20 (all of the examples of the present invention) are photographs showing SEM images and image analysis results, as in FIG. It can be seen that a heat path useful for improvement is formed. On the other hand, FIGS. 6A, 6B and 11 show No. 1 which does not satisfy any of the requirements (1) to (3). 2 to 8 and 18 (both are comparative examples). 6A, FIG. 6B, and FIG. 11, it can be seen that the heat path useful for improving the thermal conductivity in the plane direction is blocked, as in FIG. 4 described above.

In the resin-coated metal material that satisfies all the above requirements (1) to (3), the thermal conductivity in the surface direction of the resin film is 1.5 W / mK or more (preferably 1.55 W / mK or more, more preferably 1. 6 W / mK or higher, more preferably 1.65 W / mK or higher, and even more preferably 1.7 W / mK or higher). According to the present invention, as shown in the examples to be described later, a resin film having a very high thermal conductivity of 2.0 W / mK or more, and further 2.5 W / mK or more was obtained.

Here, the thermal conductivity in the surface direction is determined by the “optical AC method” manufactured by a dedicated measuring device [Shinku-Riko. Inc.] (currently Alpac Riko. Inc.). Based on the thermal diffusivity obtained using the thermal constant measuring device PIT-R1 type]], it is calculated based on the following formula (1). This apparatus is particularly useful as an apparatus for measuring the thermal diffusivity in the surface direction of a thin sample having a thickness of 0.3 mm or less.
Thermal conductivity in plane direction (W / mK)
= Thermal diffusivity (× 10 ⁻⁶ × m ² / sec) × specific heat (J / gK) × density (g / cm ³ )
... (1)

A method of measuring the thermal diffusivity in the above equation (1) will be described with reference to FIG. FIG. 7 is a schematic diagram illustrating the configuration of the measurement apparatus used in the present invention. As shown in FIG. 7, in the above measuring apparatus, a sample plate set in the apparatus (a manufacturing method will be described later) is irradiated with alternating waveform light, and the shutter is moved in the direction of the plate surface of the sample to emit light. The logarithm (ln | Tac |) of the absolute value of the AC temperature Tac measured by a moving distance L in the plate surface direction of the sample while being shielded and a thermocouple attached to the surface opposite to the surface irradiated with light And the thermal diffusivity D is calculated based on the following formula (2). In the following examples, the measurement environment was air and room temperature, and the measurement frequency [f in the following formula (2)] was 0.1 Hz.
Thermal diffusivity D (m ² / sec) = π × f (Hz) / d ² (m ⁻² ) (2)

The method for preparing the sample plate to be set in the above measuring apparatus is as follows.

First, a resin film sample for measuring the thermal diffusivity (in the examples described later, a resin-coated polyimide film cut into a width of about 5 mm and a length of about 10 mm is used) is prepared. The size of the sample to be cut may be about 5 mm in width, and the length may be slightly longer than 10 mm.

Next, as shown in FIG. 7, the light receiving surface of the sample is blackened. In detail, an attached carbon spray (not shown) is used, and the sample is blackened by spraying the carbon spray so that the surface is uniformly black from a location about 30 cm away from the sample. Furthermore, a sample plate with a thermocouple is attached to the side opposite to the light receiving surface of the sample. Specifically, as shown in FIG. 7, a necessary and minimum amount of silver paste is applied to the intersection of the thermocouple sample plate and the sample plate, and the sample and the thermocouple are bonded. At this time, if the resin film is thin, a warpage of the sample may be observed. In this case, the sample may be cut longer and fixed to the thermocouple sample plate.

Since the light receiving surface is blackened in this way and a sample plate having a couple sample plate attached to the opposite side of the light receiving surface is obtained, this sample plate is set in the above-described measuring apparatus.

In addition, the specific heat of the resin film sample in the above formula (1) was measured at room temperature using a differential scanning calorimeter (DSC220C manufactured by Seiko Instruments Inc.). In addition, in order to accurately measure the density [weight / (length × width × thickness)] of the resin film sample in the formula (1), the vertical and horizontal sizes (mm) are accurately measured using a caliper. And the film thickness (micrometer) was calculated | required from the SEM cross-sectional photograph used for the measurement of flatness.

The thermal diffusivity, specific heat, and density thus obtained were substituted into the above equation (1), and the thermal conductivity in the plane direction was calculated.

Next, the measurement procedures (1) to (3) will be described in detail.

First, cut in a plane parallel to the resin film of the resin-coated metal material to expose the cross section in the surface direction of the resin film. A cross-sectional photograph of the SEM cross section is taken of the cross section in the resin film surface direction using a scanning electron microscope (SUPRA35, manufactured by Carl Zeiss). The observation magnification was 1500 times, and SEM reflected electron images were taken in an observation region of 600 μm × 800 μm per field of view, and a total of 20 places were observed (n number = 20). The photographed SEM photograph was processed with an image analyzer (manufactured by Nireco, LUZEX AP AP 2006.11 version), and the maximum length, minimum length, and average area ratio were determined. Depending on the type of additive such as heat conductive particles contained in the resin film, the SEM image may be unclear. In that case, a SEM photograph is printed, a PET film is stretched thereon, and the part of the additive An image traced with black magic may be used for image analysis.

Regarding the above (1), in the present invention, the average value of the flatness of the heat conducting particles is preferably as large as possible, preferably 3.2 or more, and more preferably 3.5 or more. The upper limit of the average value of the flatness is not particularly limited from the viewpoint of the thermal conductivity in the surface direction, but is preferably about 20.0 in view of applicability and the like. More preferably 0.

As for the above (2), in the present invention, the higher the frequency ratio of the heat conducting particles existing in the range of the inclination angle of 0 ° or more and less than 30 °, the better, preferably 42% or more, more preferably 45% or more. It is.

As for the above (3), in the present invention, the area ratio of the heat conductive particles is preferably as large as possible, preferably 32% or more, more preferably 35% or more. The upper limit of the area ratio is not particularly limited from the viewpoint of the thermal conductivity in the plane direction. However, when workability and corrosion resistance are taken into consideration, the upper limit of the area ratio is preferably approximately 60%, more preferably 55%. .

The requirements (1) to (3) that characterize the present invention have been described above.

The heat conductive particles used in the present invention are not particularly limited, and those usually used for heat radiating members and the like can be used. Specifically, those having a high thermal conductivity of about 30 W / mK or more are preferably used, and representative examples include copper, aluminum, graphite, Al ₂ O ₃ , SiC, and the like. These are known per se as having high thermal conductivity, but when added to the resin film by appropriately controlling their shape, inclination angle, etc., as demonstrated in the examples below. The surface direction thermal conductivity of can be kept high.

The preferable average particle diameter of the heat conductive particles is generally 1 to 40 μm, more preferably 1.5 to 35 μm. The average particle diameter can be measured by, for example, a laser diffraction / scattering method (micro-track method). When using a commercial product as in the examples described later, the average particle size provided by the manufacturer may be referred to. Specifically, it is preferable to appropriately control the average particle diameter of the heat conductive particles in relation to the thickness of the resin film. If the average particle size of the heat conductive particles is too large with respect to the thickness of the resin film, the variation in the inclination angle of the heat conductive particles in the resin film becomes large, and the above requirement (2) may not be satisfied. It is. Specifically, it is preferable to control the average particle diameter of the heat conductive particles within a range of about 0.1 to 5 times the thickness of the resin film.

Commercially available products may be used as the heat conductive particles used in the present invention. Specifically, in addition to those used in the examples described below, for example, copper such as 1200YP manufactured by Mitsui Mining & Mining & Smelting Co., Ltd .; MH-8802 manufactured by Asahi Kasei Chemicals Corporation Aluminum such as MC-606, ME-12, M-701, GX-2134, BS-200; SP-20 manufactured by Nippon Graphite Industry Co., Ltd., Ito Graphite Mining Co., Ltd. And graphite such as SRP-7, CNP15, and the like.

The shape of the metal material used in the present invention is not particularly limited, and typically includes a metal plate, but other pipe materials, wire materials, bar materials, deformed materials, and the like can also be used. Further, the type of the metal material is not particularly limited, and those usually used for a housing of an electronic device component can be used. Taking a metal plate as an example, typically, a steel plate is exemplified, and a cold rolled steel plate, a hot rolled steel plate, a stainless steel plate and the like are exemplified. Also, various galvanized steel sheets such as electrogalvanized steel sheet (EG), hot dip galvanized steel sheet (GI), alloyed hot dip galvanized steel sheet (GA), Al-Zn galvanized steel sheet, and Cu galvanized steel sheet; A steel plate that has been subjected to a surface treatment such as chromate treatment or phosphate treatment; a steel plate that has been subjected to a non-chromate treatment may be used. Or a nonferrous metal plate is also applicable.

The resin film containing the heat conductive particles only needs to be formed on at least one surface (heat source side) of the metal material, and thereby, heat from the heat source is quickly diffused and transferred in the surface direction of the metal material. be able to. The resin film may be provided not only on one side but also on both sides.

The resin (base resin) constituting the resin film used in the present invention is not particularly limited, and it is preferable to select an appropriate resin mainly depending on the use of the metal material. As described above, the characteristic part of the present invention is the place where the requirements of the heat conductive particles useful for improving the planar thermal conductivity are specified, and the other requirements are not particularly limited as long as the effects of the present invention are not impaired. Because. In consideration of the fact that the metal material of the present invention is suitably used for a casing of an electronic device component and also requires good workability, it is preferable to use a polyester resin or an epoxy resin, a blend thereof or a modified resin. . Of course, the present invention is not limited to this, and various resins useful for improving processability can be appropriately selected and used. Furthermore, when corrosion resistance is also required, a resin suitable for improving corrosion resistance can be selected and used. Modification of the resin used in the present invention can be appropriately performed by those skilled in the art depending on the use of the metal material.

In addition to the above heat conductive particles and resin, the resin film may be added with additive components that are usually added to the resin film. Examples of the additive component include a rust preventive pigment, an antistatic agent, a weather resistance improving agent, and the like, and can be added within a range not impairing the function of the present invention. Alternatively, for the purpose of improving heat dissipation, well-known heat dissipation additives (typically carbon black, oxides such as Co, Ni, Cu, Mn, Ag, Sn, sulfide, carbide, etc., and further TiO 2. ₂ , ceramics, iron oxide, aluminum oxide, barium sulfate, silicon oxide, etc.) may be added.

Further, another film may be provided on the resin film, and such a metal material is also included in the scope of the present invention. For example, a known clear film may be coated on a resin film for the purpose of improving scratch resistance and fingerprint resistance.

The resin-coated metal material of the present invention is obtained by applying a coating material in which the above base resin, heat-conductive particles and, if necessary, other additives are dissolved or dispersed in a solvent, to the surface of the metal material by a known coating method and then drying. Alternatively, it can be manufactured by heat baking treatment. The coating method is not particularly limited. For example, a roll coater method is applied to the surface of a base material that has been subjected to a pretreatment (for example, phosphate treatment, chromate treatment, etc.) after cleaning the surface. And a coating method using a spray method, a curtain flow coater method, etc., passing through a hot air drying oven, drying, or baking hardening.

The content of the heat conductive particles contained in the paint differs depending on the kind of the particles and the kind of resin or solvent used in combination, and it is difficult to determine uniquely, but generally, the paint 100 The amount is preferably about 10 to 70 parts by weight, more preferably about 15 to 65 parts by weight with respect to parts by weight. Similarly, the content of the base resin contained in the paint is different depending on the type of the resin and the type of thermally conductive particles and solvent used in combination, and it is difficult to determine uniquely. In general, the amount is preferably about 5 to 35 parts by mass, more preferably about 7 to 33 parts by mass with respect to 100 parts by mass of the paint.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples, and can be implemented with modifications within a range that can meet the purpose described above and below. They are all included in the technical scope of the present invention.

Example 1
(I) Preparation of paint Heat conductive particles of symbols A to D shown below; a mixed solvent of xylene and cyclohexanone (xylene: cyclohexanone = 1: 1); polyester resin (TOYOBO CO., Ltd ) Organic solvent soluble polyester resin “VYLON (registered trademark) 650”) and melamine resin (Sumitomo Chemical Co., Ltd.) “SUMIMAL (registered trademark) M- 40ST ", solid content 80%) and a base resin (matrix resin) mixed at a mass ratio (drying ratio) of 100: 20, and mixed at a ratio shown in Table 1 and stirred vigorously with a hand homogenizer. Paints were prepared (Nos. 2 to 20 in Table 1). For reference, the average particle sizes (designated by manufacturers) of symbols A to D are also transcribed in Table 1. For comparison, a sample containing only the base resin without adding heat conductive particles was also prepared (No. 1 in Table 1).
Symbol A: Spherical copper powder (Mitsui Metal Mining 1300Y)
Symbol B1: Concave and convex copper powder (MA-C08J manufactured by Mitsui Metal Mine)
Symbol B2: Uneven copper powder (MA-C04J manufactured by Mitsui Mining & Mining)
Symbol C1: Flat copper powder (1100YP manufactured by Mitsui Mining Co., Ltd.)
Symbol C2: Flat copper powder (1400YP manufactured by Mitsui Mining & Mining)
Symbol C3: flat copper powder (1300YP manufactured by Mitsui Mining & Mining)
Symbol C4: (2L3N manufactured by Fukuda Metal Foil Industry)
Symbol D: Flat aluminum powder (GX-40A manufactured by Asahi Kasei Chemicals)

(II) Measurement of requirements (1) to (3) defined in the present invention The flatness of the heat conduction particles of requirement (1) defined in the present invention, and the inclination angle of requirement (2) is 0 ° or more and less than 30 ° The frequency ratio of the heat conductive particles existing in the range and the area ratio of the heat conductive particles of requirement (3) were measured as follows.

First, as an original plate, an electrogalvanized steel plate (plate thickness 0.8 mm, Zn deposition amount 20 g / m ² ) was prepared. Each of the coating materials prepared as described above was applied to the original plate with a bar coater, baked at a maximum temperature (PMT) of 220 ° C. for 2 minutes, and then dried to have a resin film having a thickness of 10 to 20 μm. A resin-coated metal plate was obtained.

The above-mentioned requirements (1) to (1) defined in the present invention are obtained by cutting the resin-coated metal plate obtained in this way on a surface parallel to the resin film and cutting it to about 15 mm × 25 mm according to the measurement procedure described above. 3) was measured.

(III) Measurement of thermal conductivity in the plane direction As a base material used for preparing a resin film sample for thermal diffusivity measurement, a TEFLON (registered trademark) -treated polyimide film ("Kapton 500F" manufactured by Toray DuPont, thickness 125 μm) is used. Prepared. Each paint was applied to the original plate in the same manner as in the above (II) to obtain a resin-coated polyimide film having a resin film with a thickness of 10 to 20 μm. The surface direction thermal conductivity was measured by the above-described method using a measurement sample cut from this resin film into a width of about 5 mm and a length of about 10 mm. The resin film sample used for the measurement was peeled off from the polyimide film. In the present example, the one having a surface direction thermal conductivity of 1.5 W / mK or more is regarded as acceptable (◯).

These results are summarized in Table 2.

For reference, No. 9, 10, 12, 14, 15, 16, 17, 19, 20 (examples of the present invention), and The inclination angle number distribution graphs (inclination angles 0 to 90 °) of 2 to 8, 11 and 18 (comparative examples) are shown in FIGS. 8, 9A, 9B, 12A to 12C and 13 respectively. No. in FIG. The graph of 9 is the same as the lower diagram of FIG.

From Table 2, it can be considered as follows. First, No. 1 in which the heat conductive particles in the resin film satisfy all the requirements (1) to (3) defined in the present invention. Nos. 9, 10, 12 to 17, 19, and 20 are No. in which no heat conducting particles are added. Compared to 1, a higher surface direction thermal conductivity was obtained.

In contrast, in spite of the addition of the same heat conductive particles as described above, the following examples that do not satisfy any of the requirements defined in the present invention did not provide the desired characteristics. In detail, No. which does not satisfy the aspect ratio of the above (1). 4; satisfying the flatness ratio of the above (1) and the frequency ratio of the above (2); 3: No. that does not satisfy the flatness ratio of (1) and the area ratio of (3). 2, 5, 7; No. that does not satisfy all the requirements (1) to (3) above. 6: No. not satisfying the area ratio of (3) above. No high thermal conductivity in the plane direction was obtained for 8, 10, and 18.

Claims

A resin-coated metal material in which a resin film containing heat conductive particles is coated on at least one side of a metal substrate,
When the scanning electron micrograph of the cross section in the plane direction of the resin film is subjected to image analysis, the heat conduction particles observed in the measurement visual field satisfy the following requirements (1) to (3): Resin-coated metal material with excellent thermal conductivity.
(1) The average value of the oblateness represented by the value obtained by dividing the maximum length of the heat conducting particles by the minimum length (maximum length / minimum length) is 3.0 or more,
(2) When the inclination angle between the maximum length of the heat conducting particles and the horizontal line in the plane direction is measured, the frequency ratio of the heat conducting particles existing in the range where the inclination angle is 0 ° or more and less than 30 ° is 40% or more. ,
(3) The area ratio of the heat conductive particles is 30% or more.
The resin-coated metal material according to claim 1, wherein the resin film has a surface direction thermal conductivity of 1.5 W / mK or more.
The resin-coated metal material according to claim 1 or 2, wherein the thermally conductive particles are copper, aluminum, or graphite.
Resin-coated metal material according to claim 1 or 2 used for electronic equipment parts.
An electronic device part having the resin-coated metal material according to claim 4.