JP6211942B2 - Insulating heat dissipation substrate, and LED element and module using the insulating heat dissipation substrate - Google Patents

Description

  The present invention relates to an insulating heat dissipation substrate having an insulating heat dissipation film on a metal substrate, and an LED element and a module using the insulating heat dissipation substrate.

  In modules equipped with LED (light emitting diode) elements, ICs, and the like, the amount of heat generated by the LED elements and the like increases with the demand for higher brightness and higher output, and the temperature rises. As a result, for example, in the LED element, there are problems that the emission color changes as the temperature rises and the deterioration of the LED element is promoted. Therefore, it is desired that the substrate on which the LED element is mounted not only has insulation but also efficiently radiates the generated heat (heat dissipation).

  Conventionally, a ceramic substrate such as an alumina substrate has been used as an insulating heat radiating substrate having such insulating properties and heat radiating properties. The alumina substrate is made of alumina (aluminum oxide) having high thermal conductivity and excellent durability against heat and light. However, since the alumina substrate needs to be fired at a high temperature of about 1600 ° C., it is expensive and has problems such as poor workability and difficulty in processing into an arbitrary shape and brittleness.

  Therefore, a resin substrate containing a high thermal conductivity material such as alumina in a resin has been proposed. For example, Patent Document 1 discloses a resin substrate in which both high thermal conductivity and insulating properties are improved by adding a high thermal conductive filler such as boron nitride powder or aluminum oxide powder to a silicone resin. The resin substrate has advantages such as low cost and excellent workability. However, since the resin substrate uses a resin for the base, there is a problem that the heat resistance is limited and the applied temperature range is limited.

  Patent Document 2 proposes a light-emitting element mounting enamel substrate in which a surface of a core metal such as alumina (alumina substrate or the like) is coated with an enamel layer. However, the thermal conductivity of the enamel itself is as low as 1 W / m · K or less, and good thermal conductivity is not exhibited.

JP2011-144234A (Electrochemical Industry) JP 2006-344694 A (Fujikura)

  As described above, an insulating heat dissipation substrate on which an LED element or the like is mounted is required to be excellent in workability, thermal conductivity, etc. in addition to heat dissipation and insulation, which are the original functions. In recent years, it has been desired to provide a substrate having a low firing temperature. This is because the above-mentioned alumina substrate has a very high firing temperature of about 1600 ° C., and therefore, copper having a melting point much lower than the firing temperature (copper has a melting point of about 1084 ° C.) cannot be used as a wiring material. On the other hand, when the firing temperature of the substrate is low, for example, an aluminum material having a melting point lower than that of copper (a melting point of aluminum is about 660 ° C.) can be used as a related member such as a wiring member. At the same time or because it can be integrally fired with the related member, productivity is improved.

  For example, copper wires, copper plates, copper materials plated with Sn and the like are widely used as wiring members, but recently, aluminum materials with high thermal conductivity are also used for the purpose of weight reduction. Specifically, in addition to wiring materials such as aluminum plates and aluminum wires, aluminum fins, fans, and the like are used as cooling bodies or casings that release heat to the periphery. Here, the melting point of pure aluminum is about 660 ° C. as described above, and when a pure aluminum material is used as a related member, the substrate needs to be able to be fired at a temperature lower than at least the melting point of pure aluminum. In addition to pure aluminum, aluminum alloys are also widely used for the related members. The temperature at which the aluminum alloy begins to melt is about 650 ° C. for 1000 series aluminum alloys, about 500 ° C. for 2000 series aluminum alloys, and 3000 series. The aluminum alloy is about 640 ° C, the 5000 series aluminum alloy is about 570 ° C, the 6000 series aluminum alloy is about 580 ° C, and the 7000 series aluminum alloy is about 480 ° C. The firing temperature of the substrate should be as low as possible. Considering the use of a 6000 series aluminum alloy that is widely used industrially, it is recommended that the substrate can be fired at a temperature of about 550 ° C. or less.

  The present invention has been made in view of the above circumstances, and an object thereof is an insulating heat dissipation substrate suitably used for mounting an LED element or the like, which has excellent thermal conductivity, and is about 550 ° C. or less. An object of the present invention is to provide an insulating heat dissipation substrate that can be fired even at a temperature.

  The insulated heat dissipation substrate of the present invention that has solved the above problems is an insulated heat dissipation substrate having an insulating heat dissipation film on at least one side of a metal substrate, and the heat dissipation film is amorphous with a firing temperature of 550 ° C. or less. An insulating heat dissipating material is dispersed in the inorganic oxide so that the thermal conductivity is 1.0 W / m · K or more, and the gist of the heat dissipating film is 10 to 250 μm. It is what you have.

  In preferable embodiment of this invention, the average value of the minimum distance of the said heat dissipation material which adjoins is 1.5 micrometers or less.

  In preferable embodiment of this invention, the content rate of the said thermal radiation material which occupies in the said thermal radiation film is 20 volume% or more and 45 volume% or less.

  In a preferred embodiment of the present invention, the heat dissipation material is at least one selected from the group consisting of aluminum nitride, aluminum oxide, silicon nitride, silicon carbide, boron nitride, magnesium oxide, and diamond.

  In a preferred embodiment of the present invention, the amorphous inorganic oxide is mainly composed of phosphate glass.

  In a preferred embodiment of the present invention, the metal substrate is made of aluminum, iron, copper, or stainless steel.

  The present invention also includes an LED element using any of the above-described insulated heat dissipation substrates and a module including the LED element.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in thermal conductivity, insulation, and heat dissipation, and the insulated heat dissipation board which can bake aluminum materials, such as pure aluminum and aluminum alloy, simultaneously can be provided. The insulated heat dissipation substrate of the present invention is useful as a substrate on which an LED element or the like is mounted, and a module in which the LED element or the like is mounted on the substrate has high performance.

FIG. 1 is a cross-sectional view schematically showing the configuration of an insulating heat dissipation substrate according to the present invention. FIG. 1A is an example having an insulating heat dissipation film on one side of the substrate, and FIG. This is an example having insulating heat dissipation films on both sides. FIG. 10 is a cross-sectional SEM image showing a part of the insulating heat dissipation film. FIG. 3 is a schematic cross-sectional view for measuring the thermal resistance of the insulating heat dissipation board in the embodiment.

  The insulating heat dissipation substrate of the present invention is an insulating heat dissipation substrate having an insulating heat dissipation film on at least one surface of a metal substrate, and the heat dissipation film is heated in an amorphous inorganic oxide having a firing temperature of 550 ° C. or less. The insulating heat dissipation material is dispersed so that the conductivity is 1.0 W / m · K or more, and the thickness of the heat dissipation film is 10 to 250 μm. In the present invention, since an amorphous inorganic oxide having a low firing temperature is used, not only copper, which is widely used for wiring materials, but also aluminum materials such as pure aluminum and aluminum alloys having a melting point lower than that of copper are used. can do. Furthermore, in the present invention, since the insulating heat dissipation material is appropriately dispersed in the amorphous inorganic oxide so as to exhibit high thermal conductivity, the heat conductivity of the heat dissipation film is improved. Furthermore, in this invention, since it has such an insulating heat dissipation film on a metal substrate, it is excellent in workability and can be processed into an arbitrary shape.

  Hereinafter, the insulating heat dissipation substrate 10 of the present invention will be described in detail with reference to FIG.

  As described above, the insulating heat dissipation substrate 10 of the present invention has the insulating heat dissipation film 2 on at least one surface of the metal substrate 1. Specifically, the heat dissipation film 2 may be provided on one side of the metal substrate 1 (the surface on which the LED element or the like is mounted) as shown in FIG. 1A, or as shown in FIG. As such, it may be provided on both surfaces of the metal substrate 1. Here, in consideration of thermal resistance and the like, a single-sided coating mode is preferably used. This is because the amorphous inorganic oxide such as phosphate glass contained in the heat dissipation film 2 adversely affects the thermal resistance showing the heat dissipation performance, and thus is preferably thinner. On the other hand, when flatness is required for the insulating heat dissipation substrate, a double-sided coating mode is preferable. In the case of single-sided coating, the thermal expansion coefficients of the amorphous inorganic oxide and the metal constituting the metal substrate are different, so that the insulating heat dissipation substrate is distorted.

The film thickness of the heat dissipation film 2 is preferably 10 to 250 μm in order to ensure insulation. If the film thickness of the heat dissipation film 2 is less than 10 μm, desired insulation (insulation resistance of 1.0 kV or more) cannot be obtained. On the other hand, if the film thickness of the heat dissipation film 2 exceeds 250 μm, the thermal resistance exceeds the target level of 1.0 × 10 ⁻⁴ K / W or less. The film thickness of the heat dissipation film 2 is more preferably 30 μm or more and 200 μm or less.

  The heat dissipation film 2 includes an amorphous inorganic oxide 3 having a firing temperature of 550 ° C. or less and an insulating heat dissipation material. Specifically, in the heat dissipation film 2, the insulating heat dissipation material 4 is dispersed in the amorphous inorganic oxide 3 so that the thermal conductivity of the heat dissipation film 2 is 1.0 W / m · K or more. . Here, the amorphous inorganic oxide 3 acts as a binder that connects the insulating heat dissipation materials 4, and its thermal conductivity is lower than that of the heat dissipation material 4.

  The amorphous inorganic oxide 3 used in the present invention satisfies the range where the firing temperature is 550 ° C. or less. When the firing temperature of the amorphous inorganic oxide 3 exceeds 550 ° C., the melting point of aluminum preferably used as a wiring material or a metal substrate is exceeded, and the aluminum material cannot be used.

  Here, the firing temperature is a temperature at which the amorphous inorganic oxide is actually fired, and is calculated by measuring the atmosphere inside the electric furnace with a thermocouple. Specifically, the firing temperature is a temperature at which the amorphous inorganic oxide is softened and fluidity appears, and is higher than a softening point or a glass transition point that is an index indicating characteristics of glass or the like. In this embodiment, firing is performed near the yield point. The yield point means that when the glass is heated to change from a solidified state to a liquid state (the temperature at this time is generally called the glass transition point), the coefficient of thermal expansion increases at this temperature, but the temperature is further increased. Then, a point where the coefficient of thermal expansion does not increase appears, which is called a yield point. The lower the firing temperature of the amorphous inorganic oxide 3, the better, and it is preferably 500 ° C. or lower. Note that the lower limit of the firing temperature of the amorphous inorganic oxide 3 is not particularly limited, but is preferably about 400 ° C. or higher considering the melting point of the amorphous inorganic oxide.

As the amorphous inorganic oxide 3 satisfying the above requirements, those containing a phosphate compound as a main component, such as phosphate glass, are preferable. This is because glass generally contains silicate as a main component and the firing temperature far exceeds 550 ° C. The amorphous inorganic oxide 3 mainly composed of a phosphoric acid compound used in the present invention contains the largest amount of phosphorus oxide (for example, P ₂ O ₅ ) in the amorphous inorganic oxide (for example, 50% by mass or more) and the balance is preferably at least one oxide such as Si, Ti, B, Zn, Sn, Ba, Li, K, Sb, and Na. Examples of such oxides include SiO ₂ , TiO ₂ , B ₂ O ₃ , ZnO, SnO, BaO, Li ₂ O, K ₂ O, Sb ₂ O ₃ , and Na ₂ O.

  Commercially available products can be used as the amorphous inorganic oxide 3 that satisfies the above requirements. In Examples described later, VQ0028 low melting point glass powder (standard firing temperature: 520 ° C.) manufactured by Nippon Frit Co., Ltd. was used, but the present invention is not limited to this. For example, in addition to the above, VQ0028M5 manufactured by Nippon Frit Co., Ltd. (the reference firing temperature is the same as VQ0028 and 520 ° C.) can also be used. This VQ0028M5 is a powder type, and this makes it possible to shorten the pulverization time compared to the case where the VQ0028 is used.

  Alternatively, a frit glass (powder glass) manufactured by Sekiya Rika Co., Ltd. having a firing temperature of 550 ° C. or lower can be used. Examples of the frit glass include glass containing phosphoric acid as a main component, such as phosphate glass frit; bismuth silicate glass frit, borosilicate glass frit, glass frit for low-temperature firing, and the like. In the above catalog, the glass transition point (Tg) or softening point (Ts) is described, and the firing temperature is not described. In this case, as described above, since the firing temperature is higher than Tg and Ts, it is necessary to select and use at least Tg and Ts below the upper limit of the firing temperature defined in the present invention, which is 550 ° C. or less. is necessary.

The heat dissipating material 4 used in the present invention has insulating properties and high thermal conductivity. As such an insulating heat dissipation material, for example, aluminum oxide (Al ₂ O _{3 has} a thermal conductivity of about 20 to 40 W / m · K), aluminum nitride (AlN has a thermal conductivity of about 70 to 270 W / m · K). K), silicon nitride (Si ₃ N _{4 has} a thermal conductivity of about 30-80 W / m · K), silicon carbide (SiC has a thermal conductivity of about 270 W / m · K), boron nitride (BN has a thermal conductivity) Is about 30 to 150 W / m · K), magnesium oxide (MgO has a thermal conductivity of about 40 to 70 W / m · K), diamond (a thermal conductivity is about 300 to 2000 W / m · K), and the like. Of these, aluminum oxide is most preferred because it is inexpensive and can reduce material costs.

  The insulating heat dissipation substrate 10 of the present invention is characterized in that the insulating heat dissipation material 4 is dispersed in the amorphous inorganic oxide 3 so that the thermal conductivity is 1.0 W / m · K or more. There is. In the present invention, “dispersed” means that the heat dissipation material 4 is an amorphous base material so that the insulating heat dissipation film can exhibit the above-described high thermal conductivity of 1.0 W / m · K or more. It means that the inorganic oxide 3 is uniformly dispersed in the film. Specifically, when the minimum distance is obtained by measuring the distance between adjacent heat dissipation materials 4 by the method described in the examples described later, the average value of the minimum distance may satisfy 1.5 μm or less. preferable. If the average value of the minimum distances exceeds 1.5 μm, the distance between the heat dissipating materials 4 will be too far, and there will be a low thermal conductive amorphous inorganic oxide 3 acting as a binder in the meantime. The heat conductivity of the heat dissipation film 2 itself is also lowered. The average value of the minimum distance is preferably as small as possible, more preferably 1.0 μm or less. The lower limit of the average value of the minimum distance is not particularly limited in relation to the thermal conductivity of the heat dissipation material 4, but the amorphous inorganic oxide 3 functions as a binder that connects the heat dissipation material 4, Considering the brittleness and adhesion of the heat dissipation film 2, the average value of the minimum distance of the heat dissipation material is preferably 0.05 μm or more.

  It is preferable to control the preferable content rate of the thermal radiation material 4 which occupies in the thermal radiation film 2 to 20 volume% or more and 45 volume% or less. Thereby, the average value of the minimum distance can be adjusted to an appropriate range. When the content of the heat dissipation material 4 is less than 20% by volume, the high thermal conductivity improvement effect due to the addition of the heat dissipation material 4 is not effectively exhibited. On the other hand, when the content of the heat dissipation material exceeds 45% by volume, when the heat dissipation film 2 is formed on the metal substrate 1, the content of the amorphous inorganic oxide 3 having a binder function that connects the heat dissipation materials 4 decreases. There is a possibility that the heat radiation film 2 is peeled off. More preferably, it is 25 volume% or more and 35 volume% or less.

  In order to form the heat-dissipating film 2, a mixed powder of the above-described amorphous inorganic oxide 3 and the heat-dissipating material 4; A well-known coating means may be performed using the dispersion liquid dispersed in (1). Examples of known coating means include a spray method, a dip method, a bar coater method, and a spin coat method. Thereby, it becomes possible to process into an arbitrary shape. Of the above-mentioned coating means, a spray method capable of uniformly coating a large area is most preferable.

  Here, the content rate of the heat dissipation material in the heat dissipation film is controlled by controlling the amount of the mixed powder containing the amorphous inorganic oxide 3 and the heat dissipation material 4 to the range of 20% by volume or more and 45% by volume or less of the heat dissipation material. Can be controlled within the preferred range described above.

  As the metal substrate 1, various metal substrates such as aluminum, iron, copper, and stainless steel can be used. As described above, since the amorphous inorganic oxide 3 having a low firing temperature is used in the present invention, a metal having a high melting point (for example, iron has a melting point of about 1538 ° C .; stainless steel has a different melting point depending on the type. From about 1370 to 1460 ° C .; the melting point of copper is about 1084 ° C.) to a metal having a low melting point (for example, the melting point of aluminum is about 660 ° C.), a metal substrate composed of various metals can be used. Of these, use of aluminum or copper having high thermal conductivity is more preferable.

In order to reduce the thermal resistance, which is one of the indexes representing the heat dissipation performance, it is preferable that the thickness of the metal substrate 1 is also appropriately controlled. Here, the thermal resistance is calculated by the following equation.
R _th = L / (A × λ)
In the formula, R _th : thermal resistance (K / W), L: thickness (m), A: cross-sectional area (m ² ), λ: thermal conductivity (W / m · K).

  Specifically, it is preferable to appropriately control as follows according to the type of the metal substrate 1 to be used.

  When an aluminum substrate is used as the metal substrate 1, the thickness is preferably controlled to 10 mm or less. If the thickness exceeds 10 mm, the thermal resistance of the aluminum itself increases, and the heat dissipation film 2 cannot be coated with a sufficient thickness. A more preferable thickness of the aluminum substrate is 5 mm or less. In addition, it is preferable that the minimum is about 0.1 mm or more in general.

  When an iron substrate is used as the metal substrate 1, the thickness is preferably controlled to 5 mm or less. If the thickness exceeds 5 mm, the thermal resistance of the iron itself increases, and the heat dissipation film 2 cannot be coated with a sufficient thickness. Moreover, the weight of the iron substrate is increased, and the production efficiency is reduced. The thickness of the iron substrate is more preferably 4 mm or less, further preferably 2 mm or less, and still more preferably 1 mm or less. In addition, it is preferable that the minimum is about 0.1 mm or more in general.

  When a copper substrate is used as the metal substrate 1, the thickness is preferably controlled to 20 mm or less. If the thickness exceeds 20 mm, the thermal resistance of the copper itself increases, and the heat dissipation film 2 cannot be coated with a sufficient thickness. Considering the manufacturing cost and the like, the thickness of the copper substrate is more preferably 10 mm or less, and further preferably 5 mm or less. In addition, it is preferable that the minimum is about 0.1 mm or more in general.

  When a stainless steel substrate is used as the metal substrate 1, the thickness is preferably controlled to 1 mm or less. If the thickness exceeds 1 mm, the thermal resistance of the stainless steel itself increases, and the heat dissipation film 2 cannot be coated with a sufficient thickness. A more preferable thickness of the stainless steel substrate is 0.7 mm or less. In addition, it is preferable that the minimum is about 0.1 mm or more in general.

  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
In this example, round alumina AS-30 (average particle diameter 18 μm) manufactured by Showa Denko KK was used as the heat dissipation material. An insulating heat dissipation substrate having an insulating heat dissipation film is produced using low melting point glass powder (standard firing temperature: 520 ° C.) of VQ0028 manufactured by Nippon Frit Co., Ltd. as an amorphous inorganic oxide, and occupies the heat dissipation film. The relationship between the content of the heat dissipation material, the thermal conductivity of the heat dissipation material, and the average value of the minimum distance between adjacent heat dissipation materials was investigated.

  First, 300 g of the amorphous inorganic oxide was pulverized using a ball mill under dry conditions until the average particle size became about 10 to 20 μm.

  Table 1 shows the content (volume%) of the heat radiating material in the total of (amorphous inorganic oxide + heat radiating material) of each powder of the amorphous inorganic oxide and the heat radiating material thus pulverized. These were mixed so as to be in the range, and dispersed in water to obtain various dispersions. The various dispersions thus obtained were sprayed onto a JIS1000 series aluminum substrate having a thickness of 2 mm by a spray method, and then heated and sintered at 450 ° C. to form an insulating heat dissipation film. The content ratio of the heat dissipation material contained in the heat dissipation film thus obtained is the same as the “content ratio of the heat dissipation material” described in Table 1.

  About the said heat radiating film, while measuring the thickness and thermal conductivity with the following method, the coating form was evaluated. Moreover, the average value of the minimum distance of the heat dissipation material dispersed and present in the heat dissipation film was measured as follows.

(Heat dissipation film thickness)
A total of five points were arbitrarily measured using an eddy current film thickness meter, and the average value was obtained.

(Thermal conductivity of heat dissipation film)
It measured by the laser flash method using the thermal constant measuring apparatus TC-7000 by ULVAC-RIKO. In the present example, a sample having a thermal conductivity of 1.0 W / m · K or more was regarded as acceptable.

(Applying form of heat dissipation film)
Each powder of the amorphous inorganic oxide and the heat-dissipating material was mixed, and a dispersion liquid dispersed in water was sprayed onto the substrate for coating, and then heated and sintered. The heat radiating film thus obtained was visually observed, and those in which peeling was not observed were judged good and those in which peeling was seen were judged as defective.

(Average value of the minimum distance of heat dissipating material dispersed in the heat dissipating film)
A cross section in the film thickness direction of the heat dissipation film was observed with a scanning electron microscope (SEM), and an SEM image was taken at a magnification of 500 times and an observation range of 35 mm. For the SEM image, the distance from the center of gravity of the heat dissipation material contained in the heat dissipation film to the center of gravity of the nearest heat dissipation material (distance between the centers of gravity) was measured. For all the heat dissipation materials, the distance between the centers of gravity was measured in the same manner as described above, and the average value thereof was calculated to calculate “the average value of the distances between the centers of gravity of adjacent heat dissipation materials”. Furthermore, the average value of the diameter of the said heat dissipation material was measured, and the average value of the minimum distance of the adjacent heat dissipation material was calculated | required from the following formula.
Average value of minimum distance of adjacent heat dissipation material = (Average value of distance between adjacent heat dissipation material centers of gravity)-(Average value of diameter of heat dissipation material)

  In this example, the average value of the minimum distances of the adjacent heat dissipation materials calculated in this way was determined to be 1.5 μm or less.

  These results are also shown in Table 1. The column of “Comprehensive evaluation” was provided in the rightmost column of Table 1, and all the above measurement / evaluation items were determined to be “Pass”, and any one failed was determined to be “Fail”.

  From Table 1, it can be considered as follows. First, no. As in 1 and 2, when the content of the heat dissipation material is below the preferable lower limit (20% by volume or more) of the present invention, the average value of the minimum distance between adjacent heat dissipation materials is increased, and the heat conductivity of the heat dissipation film is also low. became.

  In contrast, No. 1 in Table 1. When the content of the heat dissipation material increases as in 3 to 8 and exceeds the preferable lower limit (20% by volume or more) of the present invention, the average value of the minimum distances of adjacent heat dissipation materials is in a preferable range (1.5 μm or less). It was suppressed, and the heat conductivity of the heat dissipation film tended to increase.

  However, no. When the content of the heat dissipation material is too large as in FIG. 9 and exceeds the preferable upper limit (45% by volume or less) defined in the present invention, the average values of the thermal conductivity and the minimum distance were both good. The application form of the heat dissipation film was lowered, and the heat dissipation film was peeled off. From the above results, the heat dissipation material is appropriately dispersed in the heat dissipation film by controlling the content ratio of the heat dissipation material and the average value of the minimum distances of adjacent heat dissipation materials within a preferable range. It was found that high thermal conductivity can be secured.

Example 2
In this example, the various metal substrates described in Table 2 were used as the metal substrates; Insulating heat radiating substrates having various heat radiating films having the film thicknesses shown in Table 2 were prepared in the same manner as in Example 1 described above using 8 (heat radiating material content 45% by volume). The film thickness of the heat dissipation film was controlled by changing the number of spray coatings of the dispersion liquid on the substrate.

  With respect to the insulated heat dissipation substrate thus obtained, the thermal resistance and withstand voltage were measured as follows.

(Thermal resistance)
Using the apparatus shown in FIG. 3, the thermal resistance of the insulating heat dissipation substrate was measured based on JPCA-TMC-LED02T-2010 10.6. Specifically, an insulating heat dissipation substrate 6 is mounted on the stage 5, and an aluminum nitride heater “WALN-4” 7 manufactured by Sakaguchi Electric Heat Co., Ltd. is mounted as a heat source on the surface so that the heat dissipation film contacts the heater 7. And fixed. The periphery of the stage is covered with water and is forcibly cooled with water.

A load of 500 g was applied on the heater 7, and the heater 7, the insulating heat dissipation substrate 6 and the stage 5 were brought into close contact with each other and heated. After the temperature of the heater 7 and the temperature of the stage 5 reach a steady state, the temperature (Ts) of the heater 7, the temperature (Tb) of the stage 5, and the input power (W) are measured. The thermal resistance (Rth) of the substrate 6 was calculated. In this example, Rt of 1.0 × 10 ⁻⁴ K / W or less was accepted.
Rth (K / W) = (Ts−Tb) / W

(Insulation voltage)
Based on JISC2110-1, the withstand voltage was determined.

  Specifically, the dielectric breakdown voltage is measured when a spherical electrode with a diameter of 20 mm is grounded on the insulated heat dissipation substrate with a weight of 500 g and an electric current is applied so as to break down within 20 to 40 seconds using an AC power supply. did. In this example, the dielectric breakdown voltage measured in this way was evaluated as acceptable (with insulation) when the dielectric breakdown voltage was 1 kV or higher.

  These results are also shown in Table 2. In addition, the column “Comprehensive evaluation” is provided in the rightmost column of Table 2, and the film thickness, thermal resistance, and dielectric strength of the heat dissipation film are all marked “Pass”, and any one is not good. “Fail” was given to those that passed.

  From Table 2, No. 1 in which the film thickness of the heat dissipation film was appropriately controlled even when any of aluminum, iron, copper, and stainless steel was used as the metal substrate. Nos. 2 to 11 and 14 to 35 had low thermal resistance and good insulating properties, and were able to ensure both high thermal conductivity and high heat dissipation.

  On the other hand, No. 1 (using aluminum as the metal substrate), the thickness of the heat dissipating film was below the lower limit (10 μm) of the present invention, so that the withstand voltage of the heat dissipating film was reduced and the insulation was lowered.

  In Table 2, No. In both Nos. 12 and 13 (using aluminum as the metal substrate), the thermal resistance increased because the thickness of the heat dissipation film exceeded the upper limit (250 μm) of the present invention.

  In Table 2, No. 36 (using stainless steel as the metal substrate) is an example in which the film thickness of the substrate exceeds the preferable upper limit (1 mm or less) of the present invention, and the thermal resistance increased.

  For reference, no. FIG. 2 shows a cross-sectional SEM image showing a part of the heat dissipation film for No. 10 (Example of the present invention). In FIG. 2, the black part is a hole vacant inside the heat dissipation film. As shown in FIG. 2, it can be seen that the heat dissipation material is appropriately dispersed in the heat dissipation film.

DESCRIPTION OF SYMBOLS 1 Metal substrate 2 Heat dissipation film 3 Amorphous inorganic oxide 4 Heat dissipation material 5 Stage 6 Insulation heat dissipation substrate 7 Heater 10 Insulation heat dissipation substrate

Claims (8)

An insulating heat dissipation substrate having an insulating heat dissipation film on at least one side of a metal substrate,
The heat radiation film is softened to an amorphous inorganic oxide temperature fluidity appears is 550 ° C. or less, the so thermal conductivity is 1.0 W / m · K or more amorphous inorganic oxide Insulating heat dissipation material dispersed in the object ,
The insulating heat dissipation substrate, wherein the heat dissipation film has a thickness of 10 to 250 μm.   The insulating heat dissipation board according to claim 1, wherein an average value of minimum distances between adjacent heat dissipation materials is 1.5 μm or less.   The insulated heat dissipation substrate according to claim 1 or 2, wherein a content ratio of the heat dissipation material in the heat dissipation film is 20% by volume or more and 45% by volume or less.   The insulated heat dissipation substrate according to any one of claims 1 to 3, wherein the heat dissipation material is at least one selected from the group consisting of aluminum nitride, aluminum oxide, silicon nitride, silicon carbide, boron nitride, magnesium oxide, and diamond. .   The insulated heat dissipation substrate according to any one of claims 1 to 4, wherein the amorphous inorganic oxide is mainly composed of phosphate glass.   The insulated heat dissipation substrate according to any one of claims 1 to 5, wherein the metal substrate is made of aluminum, iron, copper, or stainless steel.   The LED element using the insulated heat dissipation board in any one of Claims 1-6.   A module comprising the LED element according to claim 7.