JP5592581B1 - Pre-coated aluminum plate and heat sink for in-vehicle LED lighting - Google Patents

Abstract

Provided are a precoated aluminum plate material and a heat sink for in-vehicle LED illumination that are excellent in heat dissipation and can suppress adhesion fatigue at a bonding portion between a heat sink and an LED element.
[Solution]
It is the precoat aluminum board | plate material 10 used for the heat sink 1, Comprising: The thermal conductivity of the aluminum board | plate material 20 is 150 W / m * K or more, The resin film 3 contains a thermosetting resin, The film thickness of the resin film 3 Is 15 to 200 μm, the resin-based film 3 has an integrated emissivity of 0.80 or more at 25 ° C. in the infrared region having a wavelength of 3 to 30 μm, and the glass transition temperature of the resin-based film 3 is that of the heat sink 1. When the temperature at which the resin-based coating 3 becomes lowest during use is T1 ° C., the temperature is T1 + 20 ° C. or less.
[Selection] Figure 1

Description

  The present invention relates to a heat sink for in-vehicle LED illumination for mounting a light emitting diode (LED) element and a pre-coated aluminum plate material for a heat sink for in-vehicle LED illumination.

  Lighting that uses a light emitting diode (LED) element as a light source is gradually penetrating the market due to its low power consumption and long life. Among them, in-vehicle LED lighting such as automobile headlights has attracted particular attention in recent years.

  However, the LED element which is a light emitting source of this LED illumination is very weak to heat, and there is a problem that when the temperature exceeds the allowable temperature, the light emission efficiency is lowered, and further, the life is affected. In order to solve this problem, since it is necessary to dissipate heat at the time of light emission of the LED element to the surrounding space, the LED lighting is provided with a large heat sink.

  Many LED die heat sinks made of aluminum (including an aluminum alloy) are used, and Patent Documents 1 to 4 disclose heat sinks having typical configurations among these heat sinks. Is disclosed.

JP 2007-172932 A JP 2007-193960 A JP 2009-277535 A JP 2010-278350 A

However, the conventional heat sink for in-vehicle LED lighting has the following problems.
Since LED lighting is repeatedly turned on and off during use, a difference in thermal expansion between the heat sink and the LED element occurs repeatedly. This repeated thermal expansion difference causes adhesion fatigue at the bonding portion between the heat sink and the LED element, creating a gap between the heat sink and the LED element, and cracking at the bonding portion of the LED element on the heat sink. Sometimes. Thereby, there exists a problem that durability of LED lighting falls.
Moreover, since the heat sink for vehicle-mounted LED illumination needs heat dissipation, the further improvement of heat dissipation is calculated | required.
Furthermore, conventional heat sinks for in-vehicle LED lighting made of aluminum die cast have a problem of low productivity and high cost, and continuous pressing with a plate material is required. Die-cast aluminum alloys are generally disadvantageous for heat dissipation because they have lower thermal conductivity than aluminum alloys for extension, and there is a limit to thin-wall molding that is effective for weight reduction. From this point, it is expected to be made into a plate.

  This invention solves the said subject, and while providing heat dissipation, while providing the precoat aluminum plate material which can suppress the adhesion fatigue of the adhesion | attachment site | part of a heat sink and an LED element, and the heat sink for vehicle-mounted LED illumination is provided. Let it be an issue.

  In order to solve the above-mentioned problems, a pre-coated aluminum sheet material according to the present invention includes an aluminum sheet material and a resin-based film (hereinafter referred to as a film as appropriate) formed on the surface of the aluminum sheet material. A pre-coated aluminum plate material used for a heat sink (hereinafter, appropriately referred to as a heat sink), wherein the aluminum plate material has a thermal conductivity of 150 W / m · K or more, and the resin film includes a thermosetting resin, The resin-based film has a film thickness of 15 to 200 μm, and the resin-based film has an integrated emissivity of 0.80 or more in an infrared region having a wavelength of 3 to 30 μm at 25 ° C., and the glass transition of the resin-based film. When using the heat sink for in-vehicle LED lighting, the temperature at which the resin-based film is lowest is T1 ° C. In other words, T1 + 20 ° C. or lower.

  According to such a structure, the heat conductivity of the heat sink using this precoat aluminum plate material is ensured because the thermal conductivity of the aluminum plate material is 150 W / m · K or more. In addition, by defining the resin type, film thickness, and glass transition temperature of the film within a predetermined range, a film having cushioning properties is formed, so that the adhesion fatigue durability of the bonded portion between the heat sink and the LED element is ensured. The Further, by defining the integral emissivity of the film, the heat dissipation of the heat sink is improved.

In the precoated aluminum sheet according to the present invention, the resin-based film preferably has a glass transition temperature of 10 ° C. or lower.
According to such a configuration, the film becomes rubbery in most use environments except for extremely severe environments.

In the precoated aluminum sheet according to the present invention, it is preferable that the resin-based film further includes a black pigment component.
According to such a configuration, the color tone of the film becomes black, and the heat dissipation of the heat sink is further improved.

In the precoated aluminum sheet according to the present invention, the resin-based film preferably has a film thickness of 15 to 50 μm.
According to such a configuration, the economic efficiency is further improved while maintaining the adhesion fatigue durability of the bonded portion between the heat sink and the LED element and the heat dissipation of the heat sink.

In the precoated aluminum sheet material according to the present invention, the crystal structure of the aluminum sheet material is preferably fiber-like.
According to such a structure, the roughness at the time of a bending process becomes small, and it is hard to produce a crack in a coating film at the time of the bending process of a precoat aluminum plate material.

  The heat sink for in-vehicle LED lighting according to the present invention includes a heat sink molded body formed by molding an aluminum wrought material (hereinafter, appropriately referred to as an aluminum plate material), and a resin-based film formed on the surface of the heat sink molded body. A heat sink for in-vehicle LED lighting, wherein the aluminum wrought material has a thermal conductivity of 150 W / m · K or more, the resin-based film includes a thermosetting resin, and the film thickness of the resin-based film Is 15 to 200 μm, and the resin-based film has an integrated emissivity of 0.80 or more at 25 ° C. in the infrared region having a wavelength of 3 to 30 μm, and the glass transition temperature of the resin-based film is the vehicle-mounted LED. When the temperature at which the resin-based film is lowest when the lighting heat sink is used is T1 ° C., it is T1 + 20 ° C. or less.

  According to such a structure, the heat dissipation of a heat sink is ensured because the heat conductivity of an aluminum extending material is 150 W / m * K or more. In addition, by defining the resin type, film thickness, and glass transition temperature of the film within a predetermined range, a film having cushioning properties is formed, so that the adhesion fatigue durability of the bonded portion between the heat sink and the LED element is ensured. The Further, by defining the integral emissivity of the film, the heat dissipation of the heat sink is improved.

The heat sink for in-vehicle LED lighting according to the present invention preferably has a glass transition temperature of the resin-based film of 10 ° C. or lower.
According to such a configuration, the film becomes rubbery in most use environments except for extremely severe environments.

In the heat sink for in-vehicle LED lighting according to the present invention, it is preferable that the resin-based film further includes a black pigment component.
According to such a configuration, the color tone of the film becomes black, and the heat dissipation of the heat sink is further improved.

In the vehicle-mounted LED heat sink according to the present invention, the resin-based film preferably has a film thickness of 15 to 50 μm.
According to such a configuration, the economic efficiency is further improved while maintaining the adhesion fatigue durability of the bonded portion between the heat sink and the LED element and the heat dissipation of the heat sink.

The precoated aluminum sheet material of the present invention is excellent in heat dissipation. Moreover, since it can suppress the adhesion fatigue | exhaustion of the adhesion | attachment site | part of a heat sink and an LED element when it uses as a heat sink, durability of LED lighting can be improved.
The heat sink for in-vehicle LED illumination of the present invention is excellent in heat dissipation. Moreover, since the adhesion fatigue | exhaustion of the adhesion | attachment site | part of a heat sink and an LED element can be suppressed, durability of LED lighting improves.

(A) is sectional drawing which shows typically the structure of the heat sink for vehicle-mounted LED illumination concerning this invention, (b) is sectional drawing which shows typically the structure of the precoat aluminum plate material of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
≪Heat sink≫
As shown to Fig.1 (a), the heat sink 1 which concerns on this invention is used for the vehicle-mounted LED lighting 100, and the surface of the heat sink molded object 2 by which an aluminum extending material is shape | molded, and the heat sink molded object 2 And a resin-based film 3 formed thereon. And the heat sink 1 prescribes | regulates the heat conductivity of an aluminum extending material, the component of the resin-type membrane | film | coat 3, a film thickness, an integral emissivity, and a glass transition temperature.
Each configuration will be described below.

<Heat sink molding>
The heat sink molded body 2 is made of aluminum formed by molding an aluminum wrought material. “Aluminum wrought material” is intended to differentiate it from current aluminum die-casting, resin, iron and other metals by limiting it to wrought material. However, an aluminum plate material excellent in productivity, precoat processability and the like is preferable. Hereinafter, the aluminum plate material will be described.
The aluminum plate material referred to in the present invention is made of aluminum or an aluminum alloy, and the aluminum plate material (aluminum plate material or aluminum alloy plate material) used in the present invention is not particularly limited, and may be a product shape or a molding method, It can be selected based on the strength required at the time of use. Generally, as the aluminum plate material for press forming, a non-heat treatment type aluminum plate, that is, a 1000 series industrial pure aluminum plate, a 3000 series Al-Mn alloy plate, a 5000 series Al-Mg series alloy. Some 6000 series Al—Mg—Si alloy plates, which are plates or heat treated aluminum plates, are used. However, since the heat sink molded body 2 has a thermal conductivity of 150 W / m · K or more as will be described later, the aluminum plate material is almost limited to 1000 series, some 3000 series, and some 6000 series.

The aluminum plate material is preferably 1000 series, and the particularly preferred composition is as follows.
[Preferable range of Si content: 0.03 to 1.00% by mass]
Si has the effect of being dissolved in the matrix and increasing the strength of the aluminum alloy plate, and the effect is improved as the Si content is increased. If the Si content is 0.03% by mass or more, the effect is more sufficient, and if it is 1.00% by mass or less, the thermal conductivity is improved and the performance as a heat sink material is improved.

[Preferable range of Fe content: 0.10 to 0.80 mass%]
Fe has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Fe content increases. If the Fe content is 0.10% by mass or more, the effect is more sufficient, and if it is 0.80% by mass or less, the thermal conductivity is improved and the performance as a heat sink material is improved.

[Preferable range of Cu content 0.30% by mass or less]
Cu has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Cu content is increased. If Cu content is 0.30 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

[Preferable range of Mn content: 0.20% by mass or less]
Mn has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Mn content increases. If Mn content is 0.20 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

[Preferable range of Mg content: 0.20% by mass or less]
Mg has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Mg content increases. If Mg content is 0.20 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

[Preferable range of Cr content: 0.10% by mass or less]
Cr has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Cr content increases. If the Cr content is 0.10% by mass or less, the thermal conductivity is improved and the performance as a heat sink material is improved.

[Preferable range of Zn content: 0.20 mass% or less]
Zn has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Zn content increases. If Zn content is 0.20 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

[Preferable range of Ti content is 0.10% by mass or less]
Ti has the effect of refining and homogenizing (stabilizing) the aluminum alloy cast structure, and has the effect of preventing casting cracks during ingot formation of the slab for rolling. If the Ti content exceeds 0.10% by mass, the effect is saturated. Moreover, if it is 0.10 mass% or less, thermal conductivity will improve. Therefore, the content exceeding 0.10% by mass is unnecessary.

In the heat sink molded body 2, the thermal conductivity of the aluminum plate is set to 150 W / m · K or more. Since the use of the heat sink molded body 2 is the heat sink 1, heat dissipation is required. In order to ensure the desired heat dissipation in the present invention, the heat conductivity of the heat sink molded body 2, that is, the aluminum plate constituting the heat sink molded body 2 needs to be 150 W / m · K or more. Therefore, the thermal conductivity of the aluminum plate is set to 150 W / m · K or more. Preferably, it is 200 W / m · K or more. The upper limit is not particularly specified, but is preferably 240 W / m · K or less from an economical viewpoint. Examples of the aluminum alloy having such characteristics include alloys having a specific product number and composition as described above.
The thermal conductivity can be measured by, for example, a laser flash method.
The aluminum plate material used for the heat sink molded body 2 may be a precoat material or an aftercoat material, but a precoat material is desirable from an economical viewpoint.

<Resin film>
The resin film 3 is formed on the surface of the heat sink molded body 2 and improves the heat dissipation of the heat sink molded body 2 and the adhesion fatigue durability of the LED element bonding portion. Here, the front surface means a surface on which the LED element is bonded to the heat sink molded body 2, and a film may be arbitrarily formed on the back surface according to the structure of the heat sink.
The resin film 3 includes a thermosetting resin. Examples of the thermosetting resin include two or more types selected from polyester resins, epoxy resins, phenol resins, melamine resins, urea resins, and acrylic resins, and the hydroxyl groups, carboxyl groups, glycidyl groups, and amino groups that both resins have. , And a combination in which isocyanate groups and the like are chemically bonded to each other. When two or more kinds of such combinations of resins are included, one resin and the other resin undergo thermosetting reaction as a main agent and a curing agent, and thus become a thermosetting resin. When the thermosetting reaction does not proceed sufficiently by the combination, it may be combined with a curing agent such as an isocyanate compound.
When these resins are included alone (for example, when the polyester resin is used alone), the coating 3 may be melted when the heat sink 1 is used. In this case, the adhesion between the heat sink 1 and the LED element 4 may occur. Since the force decreases, the durability of the heat sink 1 decreases. However, even if it is used alone, if it is combined with a curing agent such as an isocyanate compound, it becomes a thermosetting resin.

  Among film combinations that combine two or more types of resin components, for example, amino-cured polyester resins, isocyanate-cured polyester resins, melamine-cured polyester resins, phenol-cured epoxy resins, urea (urea) -cured epoxy resins, etc. When used, heat resistance and adhesion are further improved, which is more preferable. In addition, modified resins such as acrylic-modified epoxy resins and urethane-modified polyester resins can also be suitably used.

[Film thickness]
The film thickness of the resin film 3 is 15 to 200 μm. When the film thickness is less than 15 μm, the cushioning property of the coating 3 is lowered. Therefore, when the heat cycle is repeated, the bonded portion between the heat sink 1 and the LED element 4 is easily subjected to thermal fatigue, and the durability of the heat sink 1 is lowered. On the other hand, if the film thickness exceeds 200 μm, the heat resistance of the heat sink 1 decreases because the thermal resistance of the coating film becomes too large. However, in the range where the film thickness exceeds 50 μm and is 200 μm or less, the effect of improving the cushioning property and the integral emissivity is saturated. Therefore, the film thickness is preferably 15 to 50 μm from the economical viewpoint.

  As a measuring method of the film thickness of the resin film 3, it can be measured by, for example, an eddy current film thickness meter isoscope (ISOSCOPE: registered trademark).

[Integrated emissivity]
In the present invention, the resin-based film 3 has an integral emissivity in the infrared region having a wavelength of 3 to 30 μm of 0.80 or more at 25 ° C. The emissivity is a proportional coefficient obtained by dividing the infrared radiation from the object surface by the infrared radiation from the black body surface, and is defined for light of a specific wavelength at a specific temperature. Possible numerical values range from 0 (white body) to 1 (black body). The larger the number, the greater the infrared radiation. The integral emissivity is obtained by integrating this in a certain wavelength range. According to Planck's radiation type, the wavelength of infrared rays that can be generated in the practical temperature range of 0 to 100 ° C., in the vicinity of room temperature, which is the temperature range of the present invention, is in the range of 3 to 30 μm focusing. In other words, infrared light in a wavelength region that is out of the range of this wavelength region may be ignored. For these reasons, the present invention is limited to infrared rays in the wavelength region of 3 to 30 μm at 25 ° C.

  If the integral emissivity of infrared rays at a wavelength of 3 to 30 μm with respect to the resin-based coating 3 is less than 0.80 at 25 ° C., the ability to release heat as infrared rays from the surface of the resin-based coating 3 is lowered, and the product is cooled. Lack of ability to do. Therefore, the heat dissipation of the heat sink 1 is reduced. The integral emissivity of the infrared rays is preferably 0.85 or more, and more preferably 0.90 or more. Further, the upper limit value is not particularly defined, but is preferably 0.99 or less from an economical viewpoint. The integral emissivity of infrared rays at a wavelength of 3 to 30 μm can be controlled by combining the color of the film, the film thickness, the type of film, and the like.

  The integral infrared emissivity of the resin-based film 3 at a wavelength of 3 to 30 μm can be measured using a commercially available simple emissometer, or a Fourier transform infrared spectrophotometer (FTIR) or the like. Can be measured. More specifically, it can be a value measured using an emissivity system D & S AERD apparatus manufactured by Kyoto Electronics Industry Co., Ltd.

[Glass transition temperature of resin film]
The glass transition temperature of the resin-based coating 3 is T1 + 20 ° C. or lower, where T1 ° C. is the lowest temperature of the resin-based coating 3 when the heat sink 1 is used.
The glass transition temperature is one of the transition temperatures of the resin. Generally, a resin at a temperature higher than the glass transition temperature is a soft rubber, and a resin at a temperature lower than the glass transition temperature is a hard glass. In addition, the glass transition temperature here means what was measured by the differential scanning calorimetry (DSC method).

Here, “T1 ° C., which is the temperature at which the resin-based coating 3 is lowest when the heat sink 1 is used” refers to an environment in which the vehicle-mounted LED lighting 100 using the heat sink 1 is actually used, such as nighttime in the winter or morning. This means that the temperature of the use environment itself is low and there is no heat generation from the LED element 4 and the temperature is lowest. That is, it is the lowest temperature reached by the heat sink in a temperature use environment where the heat sink 1 is not exposed to a low temperature any more.
In the present invention, the cushioning property of the resin-based film 3 at the portion where the LED element 4 and the heat sink 1 in the heat sink 1 are in contact with each other, but the glass transition temperature of the resin-based film 3 is exposed to a lower temperature. If the temperature is equal to or lower than the temperature at which there is no resin, the resin-based coating 3 is always in a high temperature state above the glass transition temperature in any use environment, that is, in a rubbery state. Thereby, the resin film 3 is always soft and rich in cushioning properties. If the state is rich in cushioning properties, when the heat cycle is repeated, the bonded portion between the heat sink 1 and the LED element 4 is less susceptible to thermal fatigue, and the durability of the heat sink 1 is improved. However, in reality, the high molecular structure of a macromolecular substance is not uniform, such as the molecular weight is wide and a branched structure is formed in the molecule. I can't say that. The glass transition temperature is merely a representative value, and the transition gradually occurs in a temperature range having a certain width. In addition, since an actual automobile is designed according to a certain usage environment such as “cold region specification”, even if the glass transition temperature exceeds T1, good durability may be ensured depending on the environment. Therefore, in consideration of such circumstances, the glass transition temperature of the resin-based film 3 is T1 + 20 ° C. or less, which is a certain range to T1 ° C. that is the lowest temperature of the resin-based film 3 when the heat sink 1 is used. It shall be. A preferable range of the glass transition temperature of the resin-based film 3 is T1 ° C. or lower, and a more preferable range is T1-10 ° C. or lower.

  Since such temperature T1 is completely different depending on the country or region where the vehicle-mounted LED of the present invention is used, an optimal temperature may be selected depending on the location. More specifically, if the tropical region is assumed, it is considered that the glass transition temperature of the resin-based film 3 may be T1 + 20 = 55 ° C. or lower when T1 = 35 ° C. However, since it seems preferable to be able to target as many cars as possible, it is more preferably 10 ° C. or less. If the glass transition temperature of the resin-based film 3 is 10 ° C. or lower, the resin-based film 3 becomes rubbery in most use environments except for extremely severe environments. In addition, although it does not prescribe | regulate especially about a lower limit, Preferably it is -40 degreeC or more. The desirable range of the glass transition temperature is 5 ° C. or less, −20 ° C. or more, more desirably 0 ° C. or less, and −10 ° C. or more. The glass transition temperature here can be adjusted by changing the type and combination of resins forming the resin film 3 and the molecular structure of the resin.

It is preferable that the resin film 3 further contains a black pigment component. When the resin film 3 contains a black pigment component, the color tone of the resin film 3 becomes black. Since black has high heat dissipation, the heat dissipation of the heat sink 1 is further improved.
Specific examples of the black pigment component include carbon-based materials such as carbon black and graphite, and metal oxide-based materials such as copper, manganese, and iron. The black pigment component is preferably added in an amount of 3 to 50% by mass with respect to the resin material forming the resin film 3.

[Others]
The resin-based film 3 can contain a small amount of a colorant and additives that impart various functions within a range where the effects desired by the present invention are exhibited. For example, in order to further improve the moldability, for example, a lubricant such as polyethylene wax, carnauba wax, microcrystalline wax, lanolin, Teflon (registered trademark) wax, silicone wax, graphite lubricant, molybdenum lubricant, etc. One, two or more can be contained. In addition, as the conductive fine particles for imparting conductivity required for securing the earth required in electronic devices, for example, metal fine particles including nickel fine particles, metal oxide fine particles, conductive carbon, graphite, etc. One, two or more can be contained. Furthermore, when antifouling property is required, a fluorine compound or a silicone compound may be contained. In addition, antibacterial agents, fungicides, deodorants, antioxidants, ultraviolet absorbers, rust preventive pigments, extender pigments and the like can be included as long as the desired effects of the present invention are exhibited.

≪Pre-coated aluminum sheet≫
As shown in FIG. 1 (b), a pre-coated aluminum plate 10 according to the present invention includes an aluminum plate 20 and a resin film 3 formed on the surface of the aluminum plate 20 and is used for the heat sink 1. is there. And the thermal conductivity of the aluminum plate material 20, the component of the resin film 3, the film thickness, the integrated emissivity, and the glass transition temperature are defined.
Each configuration will be described below. In addition, about the part which is common in the heat sink 1 of above-described this invention, description is abbreviate | omitted suitably.

<Aluminum plate>
The aluminum plate 20 has a thermal conductivity of 150 W / m · K or more. The aluminum plate material 20 is almost limited to 1000 series, some 3000 series, and some 6000 series, similarly to the aluminum plate in the heat sink molded body 2.

The aluminum plate material 20 preferably has a fiber structure in crystal structure. “Fibrous” refers to a state having an elongated structure in which the aspect ratio between the major axis direction and the minor axis direction of the crystal structure is 10 times or more.
If the crystal structure of the aluminum plate member 20 is a fiber, the skin roughness during bending is reduced. Here, in the case of after-coating material, even if the skin is rough, it is only necessary to paint so that the coating film is covered from the top of the plate material, so such a limitation is unnecessary, but in the case of pre-coating material, the bent portion If the surface of the material is too rough, the coating film may crack. Therefore, it is preferable that the aluminum plate member 20 has a fiber structure in crystal structure.
The crystal structure of the aluminum plate can be determined with a microscope. When discriminating the crystal structure with a microscope, a cross section of aluminum parallel to the direction in which the aluminum is extended by rolling (rolling direction) is observed.

Next, preferable annealing conditions for realizing a fiber-like structure will be described.
The annealing conditions for realizing a fiber-like structure and providing good bending workability are preferably 130 to 280 ° C. and 1 to 10 hours. When the annealing temperature is less than 130 ° C., the characteristics vary in the annealed aluminum coil. On the other hand, when it exceeds 280 ° C., recovery and recrystallization proceed, yield strength decreases, and crystal grains become coarse. Also, when the annealing time is less than 1 hour, the characteristics in the aluminum coil vary as in the case where the temperature is low. On the other hand, if it exceeds 10 hours, factory productivity will fall.

<Resin film>
The resin-based film 3 is formed on the surface of the aluminum plate material 20 and improves the heat dissipation of the heat sink molded body 2 and the adhesion fatigue durability of the LED element bonding portion. Here, the front surface means a surface on which the LED element is bonded to the heat sink molded body 2, and a film may be arbitrarily formed on the back surface according to the structure of the heat sink.
The resin film 3 includes a thermosetting resin. Examples of the thermosetting resin include two or more types selected from polyester resins, epoxy resins, phenol resins, melamine resins, urea resins, and acrylic resins, and the hydroxyl groups, carboxyl groups, glycidyl groups, and amino groups that both resins have. , And a combination in which isocyanate groups and the like are chemically bonded to each other. And the membrane | film | coat 3 is 15-200 micrometers in film thickness, and the integral emissivity in an infrared region whose wavelength is 3-30 micrometers is 0.80 or more in 25 degreeC. Furthermore, the glass transition temperature of the resin-based film 3 is T1 + 20 ° C. or lower, where T1 ° C. is the lowest temperature of the resin-based film 3 when the heat sink 1 is used.
Since the resin-based film 3 is the same as the resin-based film 3 in the heat sink 1, description thereof is omitted here.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the scope of the present invention.
For example, a surface treatment film (not shown) may be provided on the surface of the aluminum plate material 20 by surface treatment.

<Pretreatment>
The surface of the aluminum plate 20 is preferably subjected to a ground treatment in order to improve the adhesion with the resin-based film 3. As a preferable base treatment, a conventionally known reactive type base coat and coating type base coat containing Cr, Zr or Ti can be used. That is, a phosphoric acid chromate film, a chromate chromate film, a zirconium phosphate film, a zirconium oxide film, a titanium phosphate film, a coating type chromate film, a coating type zirconium film, and the like can be used as appropriate. Organic-inorganic hybrid-type ground treatment coatings obtained by combining these coatings with organic components may also be used. In recent years, there has been a tendency to dislike hexavalent chromium due to the trend toward environmental protection. It is preferred to use.

In the present invention, as the film thickness of the base treatment film, the amount of Cr, Zr or Ti contained in the base treatment film component to the aluminum plate 20 (metal Cr, metal Zr or metal Ti equivalent value) is, for example, Using a conventionally known fluorescent X-ray method, it can be measured relatively easily and quantitatively. Therefore, quality control of the precoated aluminum sheet 10 can be performed without impeding productivity. In addition, it is preferable that it is 10-50 mg / m < ² > as a metal Cr, metal Zr, or metal Ti conversion value as an adhesion amount of a base-treatment film. When the adhesion amount is 10 mg / m ² or more, the entire surface of the aluminum plate 20 can be uniformly coated, and the corrosion resistance is improved. Moreover, if it is 50 mg / m < ² > or less, when the precoat aluminum plate material 10 is shape | molded, it will become difficult to produce a crack in the membrane | film | coat itself of a surface treatment.

  In addition, when productivity is not taken into consideration, a conventionally known process such as an anodizing process or an electrolytic etching process can be performed on the surface of the aluminum plate 20. When these treatments are performed, fine irregularities are formed on the surface of the aluminum plate member 20, so that the adhesion of the resin coating 3 is greatly improved.

  Furthermore, when the corrosion resistance is not required so much and a simple method is desired, a method of only degreasing the surface of the aluminum plate material 20 may be used. As a method of degreasing, conventionally known methods such as degreasing with an organic drug, degreasing with a surfactant drug, degreasing with an alkaline drug, degreasing with an acid drug, and the like can be used. However, in the case of organic chemicals and surfactant chemicals, the degreasing ability is slightly inferior, and therefore degreasing with an alkaline chemical or an acid chemical is more productive. The degreasing capacity of alkaline chemicals can be controlled by the main component, concentration, and processing temperature of the alkali used. However, if the degreasing capacity is strengthened, a lot of smut will be generated, and subsequent washing with water will not be performed sufficiently. On the contrary, the adhesion of the resin film 3 may be lowered. In addition, when a variety containing a large amount of magnesium as an additive element is used for the aluminum plate material 20, magnesium may remain on the surface and the adhesiveness of the resin coating 3 may be deteriorated with an alkaline chemical. Therefore, in this case, it is preferable to use or use an acid drug.

≪Pre-coated aluminum sheet manufacturing method≫
Next, an example of a method for producing a precoated aluminum sheet will be described with reference to FIG. 1 as appropriate.
About the manufacturing method of the precoat aluminum board | plate material 10, it does not restrict | limit in particular, After apply | coating the coating material containing the resin used as the base resin, and a hardening | curing agent on an aluminum board by a conventionally well-known method, it is by heating. It can be obtained by crosslinking reaction. In addition, it is preferable that the baking temperature at the time of baking a coating material shall be about 150-285 degreeC.

  Here, the coating may be applied by any means such as a brush, a roll coater, a curtain flow coater, a roller curtain coater, an electrostatic coating machine, a blade coater, or a die coater. At the same time, it is preferable to use a roll coater that is easy to work. When coating with a roll coater, the film thickness of the resin-based film 3 is controlled by appropriately adjusting the conveying speed of the aluminum plate 20, the rotation direction and rotation speed of the roll, the pressing pressure between the rolls (nip pressure), and the like. However, in general, the thickness of the resin-based film 3 that can be applied by one application operation is generally 1 to 20 μm. In the present invention, the thickness of the resin film 3 is adjusted to 15 to 200 μm.

  And when manufacturing the heat sink 1 using the precoat aluminum board | plate material 10, the precoat aluminum board | plate material 10 should just be bend | folded and shape | molded by a conventionally well-known method, and should just make it the shape of the heat sink 1. FIG.

Next, the present invention will be specifically described by comparing an example that satisfies the requirements of the present invention with a comparative example that does not satisfy the requirements of the present invention.
In this example, a heat sink for simulated in-vehicle LED lighting created by bending aluminum alloy plates with different thermal conductivities and plate thicknesses was manufactured, and a “continuous lighting test” for confirming the heat dissipation performance, and lighting on / off were performed. A “thermal cycle test” was conducted assuming durability of adhesion fatigue due to thermal expansion and heat shrinkage when repeated.

  An aluminum alloy having the composition shown in Table 1 was melted and cast into an ingot, and the ingot was chamfered and then subjected to a homogenization heat treatment at 480 ° C. The homogenized ingot was subjected to hot rolling, further cold rolling, and annealing treatment to obtain a rolled plate having a thickness of 1.0 mm. The rolling rate in cold rolling was 75%, and the annealing treatment was 240 ° C. for 4 hours. As will be described below, a coating film was formed on the surface of this rolled plate to obtain a test material. Specifically, it is as follows.

  First, a commercially available 10 W LED lighting unit was purchased and dismantled, and a die-cast heat sink was taken out and used as a benchmark heat sink. Next, the shape of this benchmark heat sink was simulated, and heat sinks as examples and comparative examples manufactured from aluminum alloy plates were manufactured. In simulating the shape, particular attention was paid to faithfully reproducing only the shape of the LED element mounting portion and the joint portion required when reassembling the LED lighting unit. The reason is that a shape that cannot be incorporated into the lighting unit before disassembly is not practical. In consideration of productivity, the shape can be made from a single plate.

  The heat sink as an example was prepared as follows. First, the surface of a rolled plate made of an aluminum alloy having various plate thicknesses and thermal conductivities was subjected to phosphoric acid chromate treatment after weak alkali degreasing. Next, the coating material which becomes the component described in the table | surface of the Example after a heating was apply | coated to the surface of one side first with the bar coater used as target thickness. Then, temporary drying was performed at 100 ° C. for 60 seconds so that the crosslinking reaction was not promoted, and the same component paint as the first surface was then applied to the opposite surface with the same bar coater. Then, the precoat aluminum plate was produced by heating the baking temperature at a material arrival temperature of 230 ° C. and a holding time in the furnace of 60 seconds. The pre-coated aluminum plate had a size of 30 cm × 30 cm, and was formed into a shape substantially equivalent to a die-cast heat sink by bending, and used as a heat sink for the test material. When the LED element substrate and the heat sink were attached, they were joined using M3 bolts and nuts. Commercially available silicon grease was applied to the bonding surface between the LED element substrate and the heat sink in order to increase the degree of contact.

Regarding the heat sink of the comparative example, the heat sink using the resin film was prepared by the same method as in the example. However, for the anodized one, an aluminum plate not subjected to any surface treatment was first bent into a predetermined shape and then subjected to sulfuric acid anodization. As sulfuric acid anodizing treatment conditions, sulfuric acid was set to 15%, and voltage, current density, and energization time were appropriately set to conditions for obtaining a predetermined film thickness. In particular, for black anodization, sealing is performed after dyeing with a black dye. Others are the same as the embodiment.
These test materials were measured and evaluated as follows.

[Thermal conductivity]
The thermal conductivity was measured by a laser flash method.

[Integrated emissivity]
The integral emissivity was measured using an emissivity D & S AERD apparatus manufactured by Kyoto Electronics Industry Co., Ltd.

[Film thickness]
The film thickness of the film was measured using an eddy current film thickness isoscope (ISOSCOPE: registered trademark).

[Heat dissipation: Continuous lighting test]
In-vehicle LED lighting is assumed to be used in various environments around the world, but lighting is actually used only at night. Under such conditions, it is considered that the most severe heat dissipation is required at night in the tropical region. Therefore, assuming such an environment, a continuous lighting test was performed in a 35 ° C. environment.
A 10 W LED element was attached to each of the heat sinks of the benchmark, the example, and the comparative example to emit light, and the heat sink temperature immediately below the LED element when the temperature reached a steady state was measured. In this case, heat dissipation was good (◯) when the temperature was equal to or lower than the benchmark, and heat dissipation was poor (x) when the temperature reached higher than the benchmark.

[Adhesion fatigue durability: Thermal cycle test]
Among the environments where in-vehicle LED lighting is used, the minimum temperature T1 ° C. is considered to be at night in winter or when it is turned off in the morning. T1 ° C. is considered to be almost the same as the environmental temperature because it is turned off. In polar regions, the temperature is about minus 40 ° C, but conversely in tropical regions it is about 35 ° C, and the usage environment is greatly different. The typical usage environment of automobiles is considered to be an environment in which the world's population is concentrated, so T1 = 10 ° C. was assumed as a representative value assuming a temperate region. Here, the adhesion fatigue durability was evaluated based on 10 ° C. or less, which is a more preferable glass transition temperature of the resin-based film.

  As a result of checking with a benchmark heat sink, in this environment, the heat sink when turned off was 10 ° C., which was the same as T1, but reached 60 ° C. when turned on. Therefore, a thermal shock test at 10 ° C. and 60 ° C. was performed by simulating repetition of turning on and off. The heat cycle condition was repeated for 1 hour at 10 ° C. and 1 hour at 60 ° C. for 1 cycle, and this was repeated 3000 cycles.

  After sticking the LED element to each heat sink of the benchmark, the example, and the comparative example via heat-resistant grease, a thermal shock test was performed, and the number of cycles when the LED element was peeled off from the heat sink was measured. When the number of cycles was equal to or higher than the benchmark, the durability of adhesion fatigue was good (◯), and when it was less than the benchmark, the durability was poor (x).

  However, since an actual automobile is designed according to the usage environment to some extent such as “cold region specification”, even if the durability becomes (×), good durability may be ensured depending on the environment. Therefore, a thermal shock test at T1 = 35 ° C. was additionally performed for those that were (x) under the above conditions, assuming a tropical region. As a result of checking with a benchmark heat sink, in this environment, the heat sink when turned off is 35 ° C., but the heat sink when turned on reaches 75 ° C. Therefore, in the additional test, thermal cycle tests at 35 ° C and 75 ° C were conducted, and the durability was changed from (x) to (△) when the number of cycles when the LED element was peeled off the heat sink was equal to or higher than the benchmark. However, in the case of being inferior to the benchmark, the durability was left as (x).

[Weight saving]
This time, when making the benchmark die-casting heat sink into a plate, the weight reduction target was set to 50% of the benchmark separately from the performance. Therefore, when the weight of the heat sink of the prototype or comparative example manufactured as a prototype is 50% or less of the benchmark, it is light (◯), and when it exceeds 50%, it is not particularly lightweight, but there is no problem in use (△). It was.
These results are shown in Table 2. In addition, the underline part in a table | surface shows having no requirements or an effect of this invention.

  As shown in Table 2, no. Since 1-11 satisfy | fill the structure of this invention, the favorable result was obtained. On the other hand, no. Since 12 to 21 did not satisfy the configuration of the present invention, the following results were obtained.

No. No. 12 was inferior in heat dissipation because the thermal conductivity was less than the lower limit.
No. No. 13 was inferior in heat dissipation because the thermal conductivity was less than the lower limit.
No. No. 14 is a white anodic oxide film, and the film thickness and integrated emissivity are less than the lower limit values, so the heat dissipation and adhesion fatigue durability were inferior.
No. No. 15 was inferior in adhesion fatigue durability because the film material was a black anodized film.
No. No. 16 was inferior in heat dissipation and adhesion fatigue durability because the film thickness and integrated emissivity were less than the lower limit values.

No. No. 17 was inferior in adhesion fatigue durability because the glass transition temperature of the film did not satisfy the regulation.
No. No. 18 was inferior in heat dissipation because the film thickness exceeded the upper limit.
No. No. 19 was inferior in adhesion fatigue durability because the film thickness was less than the lower limit.
No. No. 20 was inferior in heat dissipation because the integrated emissivity was less than the lower limit.
No. In No. 21, since the material of the film was polyester alone, the test material was melted in the thermal cycle test.

In addition, the LED heat sinks described in Patent Documents 1 to 4 are all inventions in which a shape having fins is essential or recommended, and in order to realize these shapes with aluminum, there is no choice but to do it by die casting, It corresponds to a benchmark heat sink in the present invention. The casting alloy used in the die-casting method basically has a low thermal conductivity and it is difficult to reduce the weight, so that the present invention is not satisfied. Moreover, the surface of any of the heat sinks is not described, and the adhesion durability between the LED element and the heat sink, which is a feature of the present invention, is not considered.
As shown in the present embodiment, this conventional aluminum sheet does not satisfy a certain level in the above evaluation. Therefore, this example objectively revealed that the aluminum plate according to the present invention is superior to the conventional aluminum plate.

  Although the present invention has been described in detail with reference to the embodiments and examples, the gist of the present invention is not limited to the above-described contents, and the scope of the right is interpreted based on the description of the claims. There must be. Needless to say, the contents of the present invention can be modified and changed based on the above description.

DESCRIPTION OF SYMBOLS 1 Heat sink for vehicle-mounted LED illumination 2 Heat sink molded object 3 Resin-type film | membrane 4 LED element 10 Precoat aluminum plate material 20 Aluminum plate material 100 Vehicle-mounted LED illumination

Claims (9)

An aluminum plate material and a resin-based film formed on the surface of the aluminum plate material, and a pre-coated aluminum plate material used for a heat sink for in-vehicle LED lighting,
The aluminum plate has a thermal conductivity of 150 W / m · K or more,
The resin-based film includes a thermosetting resin,
The film thickness of the resin-based film is 15 to 200 μm,
The resin-based film has an integrated emissivity of 0.80 or more at 25 ° C. in an infrared region having a wavelength of 3 to 30 μm,
The glass transition temperature of the resin-based film is T1 + 20 ° C. or less, where T1 ° C. is the lowest temperature of the resin-based film when using the heat sink for in-vehicle LED lighting. .   The precoated aluminum sheet according to claim 1, wherein the resin-based film has a glass transition temperature of 10 ° C or lower.   The precoated aluminum sheet according to claim 1 or 2, wherein the resin-based film further contains a black pigment component.   The precoated aluminum sheet according to any one of claims 1 to 3, wherein the resin-based film has a thickness of 15 to 50 µm.   The precoated aluminum plate according to any one of claims 1 to 4, wherein the crystal structure of the aluminum plate is in a fiber form. A heat sink for in-vehicle LED illumination comprising a heat sink molded body formed by molding an aluminum wrought material, and a resin-based film formed on the surface of the heat sink molded body,
The thermal conductivity of the aluminum wrought material is 150 W / m · K or more,
The resin-based film includes a thermosetting resin,
The film thickness of the resin-based film is 15 to 200 μm,
The resin-based film has an integrated emissivity of 0.80 or more at 25 ° C. in an infrared region having a wavelength of 3 to 30 μm,
The glass transition temperature of the resin-based film is T1 + 20 ° C. or less, where T1 ° C. is the lowest temperature of the resin-based film when the heat sink for vehicle-mounted LED lighting is used. Heat sink.   The heat sink for in-vehicle LED illumination according to claim 6, wherein the resin-based film has a glass transition temperature of 10 ° C. or lower.   The heat sink for in-vehicle LED illumination according to claim 6 or 7, wherein the resin-based film further contains a black pigment component.   The heat sink for in-vehicle LED illumination according to any one of claims 6 to 8, wherein the resin-based film has a thickness of 15 to 50 µm.

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