JP3936990B2 - High thermal conductivity aluminum nitride, method for producing the same, and resin composite using the same - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an aluminum nitride powder having good thermal conductivity, a method for producing the same, and a resin composite having excellent insulation and thermal conductivity obtained by mixing the aluminum nitride powder and a resin.
[0002]
[Prior art]
After surface mounting electronic circuits and electrode wirings composed of semiconductor elements on a circuit board, in order to protect them, for example, an electronic component group is packaged by being covered with an ultraviolet curable insulating resin. Resin having insulation and thermal conductivity by mixing SiO ₂ powder, Al ₂ O ₃ powder, etc. with resin in order to advance heat dissipation from these electronic components as the density and functionality increase. Composites are used. These powders also have the effect of increasing flame retardancy.
[0003]
[Problems to be solved by the invention]
However, more recent electronic devices are required to be smaller, lighter, higher density, and higher reliability. With the increase in power circuits and high-power components in surface mounting, SiO ₂ powder and A resin composite using Al ₂ O ₃ powder is insufficient, and there is a problem that a resin composite having sufficiently high thermal conductivity is desired.
[0004]
Therefore, the object of the present invention is to replace the conventional resin composite using SiO ₂ or Al ₂ O ₃ with good insulation and excellent thermal conductivity that can be used for resin heat-dissipating sheets and heat-dissipating parts for electronic parts. Another object is to provide a resin composite.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor has advanced research focusing on aluminum nitride (AlN) as a thermally conductive filler such as a filler for protecting an IC circuit, as a substitute for SiO ₂ or Al ₂ O ₃ powder. It was.
[0006]
Since the AlN powder as manufactured by the conventional AlN manufacturing method is a fine powder, the high heat conductivity inherently cannot be obtained, but the heat conductivity is high and the heat conductivity is at least 100 W / m · K or more. When obtaining powder by grinding from the state of AlN sintered body with conductivity, if the particle size distribution is adjusted, a powder having a thermal conductivity relatively close to that of the sintered body can be obtained and composite with resin The present invention has been found.
[0007]
That is, according to the present invention, first, nitriding obtained by pulverizing an aluminum nitride sintered body having a thermal conductivity of 100 W / m · K or more obtained by sintering AlN powder together with a sintering aid in an N ₂ gas atmosphere. a aluminum powder, a content of 0.1 to 10 wt% in the powder of Y ₂ O ₃ added as the sintering aid, the bulk density of the powder is 0. 5~1. 8g / cm ³ , an aluminum nitride powder characterized by a tap density of 1.0 to 2.2 g / cm ³ , a specific surface area of 0.5 to ⁵ m ² / g by BET method, and an average particle size of 1 to 10 μm; 2. When grinding an aluminum nitride sintered body having a thermal conductivity of 100 W / m · K or more, which is obtained by sintering AlN powder together with a sintering aid in an N ₂ gas atmosphere , both are non-aqueous machines. The average particle size of 1 to 10 μm by combining the pulverization step and the sieving step a method of producing an aluminum nitride powder characterized by adjusting to m ; and third, an insulating property and a thermal conductivity characterized by curing the mixture of the aluminum nitride powder and the resin described in the first item above It is intended to provide a resin composite excellent in the above.
[0008]
[Action]
AlN has been put into practical use as a crucible for manufacturing compound semiconductors because of its excellent corrosion resistance and heat resistance, and as an electronic material that makes use of its excellent thermal conductivity and electrical insulation, it has a high thermal conductivity substrate or heat dissipation component. This material is attracting attention.
[0009]
The production method of AlN powder used as these materials includes a reduction nitriding method in which a mixed composition of Al ₂ O ₃ powder and carbon powder is fired in an N ₂ gas atmosphere, and Al powder is treated with N ₂ gas or ammonia. A direct nitriding method in which nitriding is performed in a gas atmosphere is typical. However, since the AlN powder produced by these methods has low crystallinity of the powder itself, its thermal conductivity is low, and it may be poorly compatible with the resin to be mixed. The heat dissipation of the composite is not improved.
[0010]
In the present invention, a sintered body obtained by sintering AlN powder by the above-described manufacturing method together with a sintering aid in an N ₂ gas atmosphere to grow crystals, that is, a sintered body having a thermal conductivity of at least 100 W / m · K or more. For example, the aggregate is coarsely crushed with a stamp mill, and further, AlN powder obtained by adjusting the particle size constitution while inserting a sieving machine into the step of pulverizing this with a ball mill and avoiding excessive pulverization is mixed with the resin. High thermal conductivity can be imparted to the resin composite. A sintered body having a thermal conductivity of less than 100 W / m · K cannot be mixed with the resin even by adjusting the particle size after pulverization, and the desired effect cannot be obtained.
[0011]
The reason why the powder characteristics when the AlN powder obtained by pulverizing the AlN sintered body is mixed with a resin to form a resin composite is as described above is as follows.
[0012]
Y ₂ O ₃ as a sintering aid promotes the growth of AlN crystal grains during sintering, takes in oxygen in the AlN grains, and is effective in enhancing thermal conductivity. However, in the powder, aluminum, nitrogen, oxygen When the Y content in the powder is less than 0.1% by weight in terms of Y ₂ O ₃ , there is no effect of improving the sinterability, while when it exceeds 10% by weight, the heat conduction In order to inhibit the property, the content of Y ₂ O ₃ was set to 0.1 to 10% by weight.
[0013]
As the sintering aid, in addition to the above Y ₂ O ₃ , any material that does not inhibit the thermal conductivity of the AlN sintered body and that can obtain a predetermined thermal conductivity may be used. For example, alkaline earth compounds such as oxides and various salts such as CaO, SrO and BaO, or rare earth oxidation such as La ₂ O ₃ , CeO ₂ , PrO ₂ , Nd ₂ O ₃ , Gd ₂ O ₃ and Dy ₂ O ₃ As in the case of Y ₂ O ₃ , one or more compounds selected from the products can be added in an appropriate amount without inhibiting the thermal conductivity of the AlN sintered body and sufficiently obtaining the thermal conductivity.
[0014]
As for the bulk density of the powder, since the particles are grown by sintering, a powder exceeding 1.8 g / cm ³ is substantially difficult to produce, whereas if it is less than 0.5 g / cm ³ , the volume increases when kneaded with the resin. Since it increased and it was difficult to adapt to resin, it was set to 0.5 to 1.8 g / cm ³ .
[0015]
The tap density is also called processing specific gravity, and is the mass per unit volume of the powder in the vibrated container. A powder having a tap density exceeding 2.2 g / cm ³ is substantially difficult to produce, whereas 1.0 g / If it is less than cm ³ , the familiarity with the resin becomes worse, so 1.0 to 2.2 g / cm ³ was set.
[0016]
As for the specific surface area, when the BET value exceeds 5 m ² / g, the surface activity is large, the stability cannot be obtained, and the familiarity with the resin is deteriorated due to the adhering gas, etc., and it is substantially less than 0.5 m ² / g. Since the particle size becomes too large, it is not suitable for use as a resin composite, so it was set to 0.5 to ⁵ m ² / g.
[0017]
When the average particle size is less than 1 μm, the filling property is poor, and when it exceeds 10 μm, the fluidity such as smoothness and injection molding when used as a resin composite is hindered.
[0018]
Moreover, as the above-mentioned pulverization process and sieving process, a vibration mill, a roll crusher, a ball mill, a stamp mill, etc. can be used for the former, and a vibration sieve, airflow classification, etc. can be used for the latter. In view of necessity, a wet process in an aqueous system is not preferable. Furthermore, the obtained AlN powder is mixed with an epoxy resin or the like to obtain a resin composite.
[0019]
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this.
[0020]
【Example】
Toyo in the AlN powder manufactured by (Corporation) were mixed Etsu Chemical Co. of Y ₂ O ₃ powder 3 wt% N _2, was obtained by calcining for 5 hours platelike sintered body at 1850 ° C.. The thermal conductivity of this sintered body was 150 W / m · K.
[0021]
About 200 g of this AlN sintered body was put in an alumina container, and an alumina hammer was used and pulverized for 6 hours in a stamp mill at a stroke length of 4 cm and a stroke number of 100 rpm. The obtained powder was then placed in a 200 mesh sieve, passed through a low-tap sieving machine at a stroke number of 138 rpm for 30 minutes, and sieved to obtain about 90 g of the sieved powder. The same stamp mill and low-tap sieving were repeated 8 times while reusing the sieving material as a raw material to obtain about 700 g of sieving powder. At this time, the yield of each time in the low tap sieving machine was 40 to 50%.
[0022]
Next, 670 g of the powder under the sieve was put in an alumina pot having a capacity of 3.61 together with 5 kg of 3 mmφ alumina balls, and pulverized for 6 hours on a dry ball mill at an amplitude of 7.5 mm and a rotation speed of 1000 rpm.
[0023]
The AlN powder thus obtained had a specific surface area of 2.94 m ² / g and an average laser diameter of 3.66 μm. The bulk density was 0.66 g / cm ^3, a tap density of 1.20 g / cm ^3. The specific surface area was measured by a one-point BET method using a monosoap device. The average laser diameter was measured by using a laser diffraction particle size analyzer SALD-1100 manufactured by Shimadzu Corporation and dispersing the sample in an aqueous 0.2% sodium hexametaphosphate solution with an ultrasonic wave for 3 minutes. The particle size distribution of the AlN powder obtained by the measurement is shown in FIG. The bulk density and the tap density were measured according to JISK5101. The content of Y ₂ O ₃ added as a sintering aid in the powder was 2.89% by weight.
[0024]
Next, AlN powder having the above characteristics was mixed with an epoxy resin and a curing agent (mixing ratio: 70% AlN powder, 20% epoxy resin, 10% curing agent) to obtain a resin composite.
[0025]
The composite obtained above was poured into a mold and cured while still having fluidity to produce a plate-like sample of 30 × 50 × 1 mm. A thermocouple was fixed with an adhesive at a position of 10 mm in the longitudinal direction of the sample, and the opposite end 10 mm was fixed on a small hot plate with a weight made of SUS. The hot plate was set to 40 ° C. in advance, and the temperature change from the time when the sample was placed on the hot plate was measured with time. At this time, the room temperature was 20 ° C.
[0026]
For comparison, resin composites prepared in the same manner as described above using SiO ₂ powder manufactured by Admatechs Co., Ltd., model number SO-25R, and AlN powder model number HF grade (direct nitrided powder) manufactured by Toyo Aluminum Co., Ltd. The temperature change was similarly measured for the sample of the product.
[0027]
The temperature change of each sample is shown in FIG. Comparing the temperature after 20 seconds, the sample in which the SiO ₂ powder and the AlN powder are mixed is 26 ° C. and 28 ° C., respectively, while the sample in which the AlN powder of the present invention is mixed is 33 ° C. It can be seen that the rate is high.
[0028]
【The invention's effect】
As described above, according to the present invention, a highly heat-conductive AlN powder can be obtained by pulverizing an AlN sintered body. By mixing this powder with a resin, a conventional SiO ₂ powder or Al ₂ powder can be obtained. Higher thermal conductivity than that using O ₃ powder can be imparted to the resin composite.
[Brief description of the drawings]
FIG. 1 is a particle size distribution diagram of AlN obtained in Examples.
FIG. 2 is a heat conduction characteristic diagram of a resin composite obtained in an example and a comparative resin composite.

Claims (3)

An aluminum nitride powder obtained by pulverizing an aluminum nitride sintered body having a thermal conductivity of 100 W / m · K or more obtained by sintering AlN powder together with a sintering aid in an N ₂ gas atmosphere, a content of 0.1 to 10 wt% in the powder of Y ₂ O ₃ added as sintering aid, the bulk density of the powder is ^{0. 5~1. 8g / cm 3} , a tap density of 1.0 An aluminum nitride powder having a specific surface area of 0.5 to ⁵ m ² / g and an average particle diameter of 1 to 10 μm, up to 2.2 g / cm ³ , a BET method. When pulverizing an aluminum nitride sintered body having a thermal conductivity of 100 W / m · K or more, which is obtained by sintering AlN powder together with a sintering aid in an N ₂ gas atmosphere, a non-aqueous mechanical pulverization process. And an sieving step to adjust the average particle size to 1 to 10 μm . A resin composite having excellent insulation and thermal conductivity, wherein the mixture of the aluminum nitride powder and the resin according to claim 1 is cured.

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