JP2009136848A - Heat radiation coated metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiation coated metal plate which efficiently conducts heat from a heat generation source to a face at which heat radiation is performed, efficiently performs heat radiation in the face at which heat radiation is performed, and has satisfactory workability. <P>SOLUTION: A chemical film 3 is formed on the surface of a metal plate 4, the face of a part of the chemical film surface 3 is provided with a thermally conductive organic resin film 5 containing a heat conductive filler of 5 to 80 vol% and having a film thickness of 1 to 50 μm, and further, the surface of a part of the chemical film surface is provided with a heat radiative organic resin film 1 comprising a heat radiative filler 2, thus a heat radiation coated metal plate 7 having high thermal conductivity, heat radiability and workability can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-dissipating coated plate for the purpose of heat dissipation from a heat generating part of a general electronic device or heat generation from a heat generating part such as a plasma display panel, a liquid crystal backlight, an organic EL panel, an inverter.

  In recent years, electronic components such as ICs used in various electronic devices have been highly integrated, and in order to meet the demand for miniaturization of electronic devices, etc., electronic components such as ICs are densely packed in a small space. By disposing, heat dissipation measures against heat generation in the housing are a big problem. In other words, when the temperature rises, the characteristics of the electronic component such as an IC may change the characteristics of the electronic component and cause malfunction of the device, or the electronic component itself may fail.

  On the other hand, while the amount of heat generated from semiconductor devices such as CPUs, which are increasing in speed, is increasing, various types of electronic devices are becoming smaller and lighter and thinner. In order to maintain its performance and function, it is necessary to sufficiently remove the generated heat, and an efficient heat dissipation system is required.

  For this purpose, conventionally, a heat sink is sometimes used to suppress the temperature rise of the electronic component during use of the electronic device or the like. This heat radiating plate radiates heat from the electronic component by conducting heat generated by contacting the heat generating portion to the heat radiating plate, and is generally made of a material having high thermal conductivity such as copper or aluminum. However, in a method in which heat generated from electronic components such as ICs is simply released to the outside by heat conduction, it is necessary to forcibly cool the heat sink when the amount of heat generation becomes large. There are a heat sink type that increases the surface area, and a method of forcibly cooling the heat generating portion using a fan motor. With such a method, it has been difficult to reduce the size and weight of the apparatus as described above.

In order to solve this problem, a method of dissipating heat by attaching a sheet made of a material having a high thermal emissivity and a laminated product of a sheet made of a material having a high thermal conductivity to a heat generating portion has been proposed. (Patent Document 1)
In this method, instead of forcibly cooling, some heat is radiated from the side of a sheet made of a material having a high thermal emissivity, which is effective in miniaturizing the apparatus. However, as described above, in the situation where the speed of the CPU and the like and the high integration of the electronic parts such as the IC are required, and the device is becoming smaller and lighter and thinner, the heat dissipation performance is sufficient. There was a need for a more efficient heat dissipation system.

JP-A-8-167682

In addition, there is a heat radiating sheet corresponding to the reduction in size and weight of various electronic devices for solving the above-mentioned problems and efficiently guiding the heat generated from the electronic components to the outside and further radiating the heat by heat radiation. Proposed. (Patent Document 2)
However, the heat-dissipating sheet is a laminate of a heat-radiating precoat material and a heat-conducting pressure-sensitive adhesive layer sheet, which causes a problem that it is very expensive. Moreover, when a heat conductive adhesive layer is as thick as about 400 micrometers described in the Example, there exists a problem that heat resistance becomes large and the heat dissipation effect is not enough. Also, because the heat conductive adhesive layer sheet is soft and the adhesiveness with the heat radiation precoat material is not sufficient, when press molding, there are cases where severe processing may not be possible, even if it can be processed, In the case of a quality problem that the corrosion resistance of the processed part is inferior, and in the case of a crack or scratch of a large pressure-sensitive adhesive layer, there is a problem that the product value is lost and the productivity is lowered and the cost is increased.

JP 2005-101025 A

  An object of the present invention is to obtain a heat-dissipation-coated metal plate having good thermal conductivity, heat dissipation, and formability at low cost.

  As a result of intensive research, the present inventors have provided a chemical conversion film on a metal plate, provided a part of the surface with a heat conductive organic resin film containing a heat conductive filler, and further provided a part of the surface with a heat conductive film. It has been found that by providing a heat-radiating organic resin film containing a radioactive filler, moldability and heat dissipation can be improved at low cost. And further experiment was repeated, and those appropriate amounts were found and it came to complete this invention.

  That is, a chemical conversion film is formed on the surface of the metal plate, and a part of the chemical conversion film surface is provided with a heat conductive organic resin film containing 5 to 80 vol% of a heat conductive filler and having a film thickness of 1 to 50 μm. Furthermore, a heat-radiating organic resin film containing a heat-radiating filler is provided on a part of the surface of the chemical conversion film.

  The heat-dissipation-coated metal plate described above, wherein the heat conductive organic resin film has a surface roughness (Ra) of 1 μm or less.

  The heat-dissipating metal plate described above, wherein the glass transition temperature (Tg) of the thermally conductive organic resin film is 60 ° C. or less.

  The heat conductive organic resin film contains at least one of heat conductive fillers composed of boron nitride, aluminum nitride, silicon nitride, silicon carbide, alumina, zirconia, magnesium hydroxide, and aluminum hydroxide. The heat-dissipation-coated metal plate.

  The heat-dissipating coated metal sheet, wherein the heat-radiating organic resin film contains one or more of heat-radiating fillers composed of titanium oxide, carbon black, graphite, and carbon fibers.

  The heat-dissipation-coated metal sheet of the present invention has good heat dissipation at low cost and has excellent moldability, so that heat generated from electronic components can be dramatically improved especially in a small space that has not been available in the past. It is suitably used as a heat-dissipating painted metal plate that escapes to the outside.

  In the present invention, the base metal plate is not particularly limited, for example, an aluminum plate, a stainless steel plate, a low carbon steel, a high carbon steel, a steel plate made of a low alloy steel used for a high tensile steel plate, or the like, or A plated steel sheet having a surface plated with these steel sheets as a base material is used. In particular, it has sufficient strength to form and hold a heat radiating member, has sufficient moldability during drawing and bending, and can dissipate heat generated inside more quickly to the outside. 1000 series, 3000 series, and 5000 series aluminum plates having excellent thermal conductivity are preferred.

  The chemical conversion film provided on the metal plate is not particularly limited as long as it is interposed between the surface of the metal plate and the organic resin film to enhance the adhesion between them. Specifically, there are a coating type and a reactive type, and there is no particular limitation, but a reactive chemical conversion film having good adhesion is mainly used for both the metal plate and the resin film. The reactive chemical conversion film is specifically a film formed with a treatment liquid such as phosphate chromate, chromate chromate, zirconium phosphate, and titanium phosphate. In particular, a phosphoric acid chromate-treated film is preferable in terms of cost and versatility. Such a chemical conversion film is applied by spraying a predetermined chemical conversion treatment liquid on the aluminum plate or immersing the alloy plate in the treatment liquid at a predetermined temperature for a predetermined time. In addition, in order to remove dirt on the metal surface or adjust the surface properties before providing the chemical conversion film, the metal plate may be acid-treated (washed) with sulfuric acid, nitric acid, phosphoric acid, etc., or caustic soda, phosphorus It is desirable to perform alkali treatment (washing) with acid soda, sodium silicate, or the like. Surface treatment by such cleaning is also performed by spraying a predetermined surface treatment liquid on the metal plate or immersing the metal plate in the treatment liquid at a predetermined temperature for a predetermined time.

  Next, a heat conductive organic resin film and a heat radiation organic resin film are formed on the chemical conversion film surface. As for the surface on which the resin film is formed, a heat conductive organic resin film is appropriately formed on a surface where heat conductivity is required, and a heat radiation organic resin film is appropriately formed on a surface where heat radiation is required. It ’s fine.

  The heat conductive organic resin film is formed by baking a paint containing a base resin and a heat conductive filler as essential components, and dissolving and dispersing them in a suitable solvent. The base resin and the thermal radiation filler are contained as essential components, and a paint in which these are dissolved and dispersed in an appropriate solvent is baked and applied.

  As a method of applying and baking the thermally conductive organic resin film and the thermally radiative organic resin film, a paint is directly applied to the surface of the chemical film by a roll coater or a bar coater, and is processed in an oven at a predetermined temperature for a predetermined time. It is appropriate to bake and dry.

  The base resin of the heat conductive organic resin film and the heat radiation organic resin film provided on the surface of the chemical film is an epoxy resin, a fluorine resin, an acrylic resin, a polyester resin, or a silicon polyester generally used for a pre-coated metal. An epoxy resin, an acrylic resin, a polyester resin, and the like are preferable in terms of cost and versatility.

  The said heat conductive organic resin film | membrane contains 5-80 vol% of heat conductive fillers in a film | membrane. When the heat conductive filler is less than 5 vol%, the absolute amount of the heat conductive filler is small, and the heat dissipation is reduced. Moreover, when it exceeds 80 vol%, the ratio of the resin component used as a binder will be low, and a film | membrane will become weak, and workability will fall.

  The film thickness of the heat conductive organic resin film is 1 to 50 μm. When the film thickness is less than 1 μm, the material is partially exposed from the thermally conductive organic resin film, or even if it is not exposed, a very thin portion increases and the workability deteriorates. On the other hand, if it exceeds 50 μm, the thermal resistance of the film increases and the heat dissipation performance decreases. Moreover, bending workability falls.

  The surface roughness (Ra) of the thermally conductive organic resin film is preferably 1 μm or less. By setting the surface roughness (Ra) to 1 μm or less, the adhesion with the heat generating part is improved, and the heat conduction from the heat generating part becomes smooth, so that the heat dissipation is improved.

  The glass transition temperature (Tg) of the thermally conductive organic resin film is preferably 60 ° C. or lower. By setting the glass transition temperature (Tg) to 60 ° C. or lower, flexibility and deformability of the heat conductive organic resin film are improved, and as a result, adhesion to the heat generating portion is improved, and heat conduction from the heat generating portion. Improves the heat dissipation.

  The thermally conductive filler contained in the thermally conductive organic resin film is preferably at least one selected from boron nitride, aluminum nitride, silicon nitride, silicon carbide, alumina, zirconia, magnesium hydroxide, and aluminum hydroxide. It consists of more than seeds. Particularly preferably, aluminum nitride is preferable in terms of thermal conductivity, and alumina is preferable in terms of cost and versatility. In general, the thermal conductivity of organic resins is as low as about 0.1 to 0.5 W / m · K. In order to improve thermal conductivity, the thermal conductivity is several W / m · K to several It is necessary to add a material having a high thermal conductivity of 100 W / m · K and higher than that of the organic resin, and this high thermal conductivity material is referred to as a thermally conductive filler.

  The heat radiation organic resin film provided on the chemical conversion film surface contains a heat radiation filler. The thermal radiation filler is composed of at least one selected from titanium oxide, carbon black, graphite, and carbon fiber. Particularly preferred are carbon black and graphite from the viewpoint of thermal radiation. The thermal radiation filler is a substance that lowers the temperature of the material by a heat radiation mechanism called “thermal radiation” different from “thermal conduction”. That is, when the heat-radiating filler absorbs heat and the temperature rises, the molecules and atoms constituting it become excited. However, since the excited state is unstable, molecules and atoms try to return to a stable state by releasing energy in the form of infrared rays. Due to the energy released at this time, the temperature of the material decreases.

The thermal radioactive filler is added in an amount of 1 to 20 parts by mass with respect to the organic resin component 100. When the addition amount is less than 1 part by mass, the absolute amount of the heat-radiating filler is small and the heat dissipation is reduced. Moreover, when it exceeds 20 mass parts, since the further improvement of thermal radiation property is not seen even if the addition amount is increased, it becomes a cost increase.

  A lubricity imparting component may be added to the heat conductive organic resin film and the heat radiating organic resin film for the purpose of further improving processability. As addition amount, it is preferable that it is 30 mass parts or less with respect to 100 mass parts of organic resins. When the lubricity-imparting component exceeds 30 parts by mass, the solvent resistance and blocking properties are reduced, and coating film residue is generated during processing, which is not suitable as a material for electronic equipment. The types of lubricity-imparting agents used at this time include olefinic waxes such as polyethylene wax, fluororesins such as PTFE (polytetrafluoroethylene), paraffinic wax, microcrystalline wax, beeswax, lanolin, carnauba wax, etc. Is mentioned.

  Solvent, matting agent, leveling agent, pigment dispersion used in ordinary paints to ensure the paintability and general performance as a precoat material to the heat conductive organic resin film and the heat radiation organic resin film An agent, an anti-bacterial agent, and the like may be appropriately contained.

Hereinafter, the present invention will be described in detail with reference to examples. An aluminum plate (material: JIS A5052, plate thickness: 0.5 mm) is degreased with a commercially available aluminum degreasing agent, washed with water, and then treated with a commercially available phosphoric acid chromate treatment solution. The paint was applied on both sides with a roll coater under the conditions shown in Table 1, and baked at a PMT (maximum plate temperature) of 200 ° C to 250 ° C. Thus, a heat-dissipation-coated metal plate schematically shown in FIG. 1 was manufactured. In the figure, 1 is a heat conductive organic resin film, 2 is a heat conductive filler, 3 is a chemical conversion film, 4 is an aluminum alloy, 5 is a heat radiation organic resin film, 6 is a heat radiation filler, and 7 is a heat-dissipation coated metal plate. is there.
The obtained heat-dissipation-coated metal plate for electronic device parts was subjected to a performance test by the following test method.

  The heat dissipation is an evaluation method for confirming the heat dissipation capability from the electronic parts of the heat-dissipated coated metal plate. The temperature of the power transistor after 10 minutes was measured by the following method, and the temperature drop difference from the comparative product was ◎: 25 ° C. or more, ○: 15 ° C. or more to less than 25 ° C., Δ: 5 ° C. or more to less than 15 ° C., × : Evaluation was made based on the standard of less than 5 ° C. and no effect. In addition, the comparative product assumed the conventional heat sink, and produced it by sticking a commercially available heat conductive sheet on the aluminum plate used for the said Example. The obtained heat-dissipation-coated metal plate and a comparative product were cut into 30 mm × 30 mm, attached to a power transistor upright with a support as shown in FIG. 2, and the electronic component was heated by applying an applied power of 4 W, The temperature after 10 minutes with a constant applied power was measured. In the figure, 1 is a heat conductive organic resin film, 2 is a heat conductive filler, 3 is a chemical conversion film, 4 is an aluminum alloy, 5 is a heat radiation organic resin film, 6 is a heat radiation filler, 7 is a heat-dissipation coated metal plate, 8 is a power transistor and 9 is a thermocouple.

Bending workability is 180 degree 3T bending with the heat conductive organic resin film surface outside, and the crack of the resin film layer is visually observed, ◎: No crack of coating film, ○: Very slight coating film Evaluation was made based on the criteria of cracking but good, Δ: cracking of a small coating film can be used, and x: not being usable with cracking of a large coating film.
Furthermore, after the crack was observed, a cellophane tape was adhered to the bent part, and a tape test was conducted to observe the degree of peeling of the coating film when the tape was peeled off rapidly. ○: No peeling, Δ: Minor peeling Possible, x: Evaluation was made based on the criteria for use with peeling.
The obtained performance test results are shown in Table 1.

As is apparent from the results shown in Table 1, Invention Example No. As for 1-24, both heat dissipation and bending workability are favorable.
On the other hand, No. which is a comparative example. Any one of 25-28, heat dissipation, and bending workability is inferior, and it is unsuitable as a heat-radiation coating metal plate for electronic devices. That is, no. No. 25 has a thin film of the heat conductive organic resin film, the heat conductive filler falls off, and the bending workability is inferior. No. No. 26 has a thick thermally conductive organic resin film, a large thermal resistance, poor heat dissipation, and poor bending workability. No. No. 27 is inferior in heat dissipation because the absolute amount of the thermally conductive filler in the thermally conductive organic resin film is small. No. No. 28 is inferior in bending workability because the absolute amount of the heat conductive filler in the heat conductive organic resin film is large.

It is sectional drawing which shows typically the thermal radiation coating metal plate of this invention. It is sectional drawing which shows typically the apparatus which evaluates the heat dissipation using the heat-radiation coating metal plate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal conductive organic resin film 2 Thermal conductive filler 3 Chemical conversion film 4 Aluminum alloy 5 Thermal radiation organic resin film 6 Thermal radiation filler 7 Heat-dissipation coating metal plate 8 Power transistor 9 Thermocouple

Claims (5)

A chemical conversion film is formed on the surface of the metal plate, and a part of the chemical conversion film surface is provided with a heat conductive organic resin film containing 5 to 80 vol% of a heat conductive filler and having a film thickness of 1 to 50 μm. A heat-dissipating coated metal sheet, characterized in that a heat-radiating organic resin film containing a heat-radiating filler is provided on a part of the chemical film surface. The heat-dissipating coated metal sheet according to claim 1, wherein the heat conductive organic resin film has a surface roughness (Ra) of 1 µm or less. The heat-dissipating metal plate according to claim 1, wherein a glass transition temperature (Tg) of the thermally conductive organic resin film is 60 ° C or lower. The heat conductive organic resin film contains at least one of heat conductive fillers composed of boron nitride, aluminum nitride, silicon nitride, silicon carbide, alumina, zirconia, magnesium hydroxide, and aluminum hydroxide. The heat dissipating coated metal plate according to claim 1. The heat-radiating coated metal sheet according to claim 1, wherein the heat-radiating organic resin film contains at least one of heat-radiating fillers composed of titanium oxide, carbon black, graphite, and carbon fibers.

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