JP7092303B2 - Method for manufacturing negative thermal expansion manganese nitride fine particles and manganese nitride fine particles - Google Patents

Description

The present invention relates to a method for stably obtaining a manganese nitride exhibiting excellent negative thermal expansion.

With the advanced development of industrial technology, the precision, miniaturization, and complexity of equipment and devices have progressed, and the division, shape control, and management of constituent members have become extremely important. Therefore, it is required to control even thermal expansion, which can be said to be the fate of solid materials. Even with a slight displacement of about 10 ppm (10 ^-5 ) in line distortion from a general sense, semiconductor device manufacturing that requires high precision at the nanometer level and slight distortion of parts are serious in function. It is fatal in fields such as precision equipment that have a negative impact. Further, in a device in which a plurality of materials are combined, serious obstacles such as interface peeling may occur due to the difference in thermal expansion of each constituent material. For example, there is a strong demand for thermal expansion control in many industrial fields such as processing machines, semiconductor manufacturing equipment, optical equipment, measuring equipment, and electronic devices.

For this reason, various negative thermal expansion materials that "shrink when heated" have been developed as thermal expansion inhibitors. Among them, the manganese nitride Mn ₃ AN (A: Cu-Ge, Zn-Sn, Ga-Sn, etc.) developed by the present inventor is 1) cubic, isotropic, free from distortion and defects, and has a function. 2) High rigidity (Young's modulus E to 200 GPa), 3) It has excellent characteristics as a thermal expansion inhibitor, such as being composed only of inexpensive and environmentally friendly elements such as Mn, Zn, and Sn. (Patent Document 1).

In particular, in the field of electronic devices, where miniaturization, high functionality, and complexity are rapidly advancing, the difference in thermal expansion between constituent materials causes serious problems such as peeling and disconnection, and control of thermal expansion is an urgent issue. .. Thermal expansion control of members such as resin films, adhesives, interlayer fillers, and substrates is indispensable for thermal expansion control in the field of electronic devices, but it is assumed that these members will be used in a size of about several μm. In order to realize this, it is necessary to reduce the size of the thermal expansion inhibitor from submicron to about 1 μm. However, it is disclosed that when Mn ₃ Cu _0.5 Ge _0.5 N powder or Mn ₃ Zn _0.5 Sn _0.5 N powder is pulverized, the operating temperature range shifts to a lower temperature and the volume change due to linear thermal expansion becomes smaller. As described above (Non-Patent Document 1), there is a problem that the negative thermal expansion is significantly impaired by the fine particle formation of manganese nitride. Various attempts have been made to solve this. For example, in Non-Patent Document 2, when the average particle size <D> of GaN _x Mn ₃ powder (x = 1 or 0.9) is 30 nm or less, ΔT The linear thermal expansion coefficient α shows a negative thermal expansion property of −70 ppm / K in a temperature range of = 50 ° C., but when <D> is 10 nm or less, α is -30 ppm / K or in the range exceeding ΔT = 100K. It is disclosed that it will be -21 ppm / K. However, this <D> value gives an indication of the size of the single crystal region in X-ray diffraction, and is not directly related to the actual particle size, and still has both fine particle size and negative thermal expansion. The technology to control it has not been clarified.

Japanese Patent No. 5099478

Masayoshi Ichiko and Koji Takenaka, Journal of the Japan Institute of Metals 77, 415 (2013) J. C. Lin et al., Appl. Phys. Lett. 107, 131902 (2015) and its supplementary information

An object of the present invention is to provide a method for stably obtaining a group of manganese nitride fine particles having excellent negative thermal expansion by optimizing the composition of the manganese nitride raw material and the conditions for micronization.

In the method for producing the manganese nitride fine particle group of the present invention, the manganese nitride raw material is pulverized so that the volume frequency center particle size (median diameter) by the laser diffraction / scattering type particle size distribution evaluation method is 3 μm or less and It is characterized by obtaining a manganese nitride having a negative thermal expansion property.
According to the manufacturing method, by providing the above configuration, a manganese nitride having excellent negative thermal expansion can be stably supplied at low cost.

The pulverization is preferably a ball mill. As the ball mill, a planetary ball mill is more preferable, and a wet planetary ball mill is particularly preferable.
In the manufacturing method, it is preferable to carry out the ball mill under the conditions of a rotation speed of 30 to 400 rpm and a rotation time of 1 to 12 hours.
Further, it is preferable to put an organic solvent in a ball mill in addition to the manganese nitride raw material.
It is preferable that the manganese nitride fine particle group is an inverted perovskite type crystal.
When the manganese nitride fine particle group has a median diameter of 2 μm or less, it is preferable that the linear expansion coefficient α is −30 ppm / K or less in a temperature range of 250 to 450 K, at least in a temperature range of ΔT = 30 K. Here, when α is -30 ppm / K or less, it means that the absolute value of α is 30 ppm / K or more and takes a negative value.
Further, it is preferable to have a step of dispersing the manganese nitride fine particles in a liquid, allowing them to stand still, recovering the supernatant, and distilling and drying the supernatant to obtain a purified manganese nitride.

The group of manganese nitride fine particles of the present invention is characterized by exhibiting a negative thermal expansion having a median diameter of 2 μm or less and a linear expansion coefficient α of −48 ppm / K or less.
The manganese nitride fine particle group preferably has a composition represented by the general formula (1) in at least a part of its structure.
Mn _{3 + y} M ¹ _{1- (x + y)} M ² _x N _z … (1)
In the general formula (1), M ¹ is Ga, Zn or Cu, M ² is Ge or Sn, and 0 <x <1, −0.3 <y <1, 0 <z <1. It is 1.

According to the present invention, by optimizing the starting composition and the conditions for atomization, it is possible to stably and at low cost provide a group of manganese nitride fine particles having excellent negative thermal expansion.
By mixing and compounding such a group of manganese nitride fine particles with a resin having a positive expansion coefficient, it is possible to supply a material for controlling the thermal expansion coefficient.

FIG. 1 shows the particle size distribution of Mn ₃ Ga _0.9 Sn _0.1 N _0.9 before pulverization (coarse powder) (a) and after pulverization (b). FIG. 2 is a graph comparing the negative thermal expansion of Mn ₃ Ga _0.9 Sn _0.1 N _0.9 after coarse powder (as-grown) and pulverization (ball mill). FIG. 3 is a graph showing the particle size distribution of the raw material (a) of Smartec-H and the fine particles (b) after pulverization in Preparation Example 1. FIG. 4 is a graph showing the particle size distribution of the raw material (a) of Smartec-M and the fine particles (b) after pulverization in Preparation Example 1.

FIG. 5 is a graph showing the particle size distribution of the raw material (a) of Smartec-H and the fine particles (b) after pulverization in Preparation Example 2. FIG. 6 is a graph showing the particle size distribution of the raw material (a) of Smartec-M and the fine particles (b) after pulverization in Preparation Example 2. FIG. 7 is a graph showing the particle size distribution of the raw material (a) of Smartec-H and the fine particles (b) after pulverization in Preparation Example 3. FIG. 8 is a graph showing the particle size distribution of the raw material (a) of Smartec-M and the fine particles (b) after pulverization in Preparation Example 3. FIG. 9 is a graph showing the effect of pulverization on the negative thermal expansion of Smart-M.

The method for producing a group of manganese nitride fine particles of the present invention is a manganese nitride having a volume frequency center particle size (median diameter) of 3 μm or less and negative thermal expansion by a laser diffraction / scattering type particle size distribution evaluation method. Is obtained by crushing a manganese nitride raw material. Hereinafter, the present invention will be described in detail. The manganese nitride fine particles referred to in the present invention are aggregates or powders of a plurality of manganese nitride particles and do not refer to one of the particles. Therefore, they are simply "manganese nitride fine particles" or "manganese". Also referred to as "nitride".
As the method for pulverizing the manganese nitride raw material, either dry pulverization or wet pulverization can be used.
Dry crushers include, for example, high-speed rotary impact mills, jet mills, roll mills, ball mills (rolling type, vibration type) and medium stirring mills. In particular, the particles collide with each other, thereby removing the sharp edges of the crushed particles to form rounded particles, which can contribute to the prevention of contact short circuits between the particles during the subsequent insulation coating. , Jet mill is preferably used. Dry pulverization is mainly a continuous process, and is usually performed by a process combined with a classification process. The classification step is a process of loosening raw materials, removing foreign substances, or adjusting the particle size by providing a classification mechanism inside the crusher.

Wet grinders include, for example, ball mills (rolling, vibrating, planetary mills, etc.), medium stirring mills, colloidal mills, and the like. The batch type is the mainstream for wet pulverization, and it is suitable for producing particles having an average particle size of submicron or less, specifically 1 μm or less. However, liquid-soluble raw materials cannot be applied.

In the present invention, any of the above-mentioned pulverization methods may be used, or two or more of these methods may be combined, but a dry or wet pulverization method using a ball mill is preferable, and a dry or wet pulverization method using a planetary ball mill is preferable. More preferred. Among them, the crushing pot and media (crushing balls), which are the contact surfaces of manganese nitride, can be made of zirconia, which has a relatively high hardness and is hard, and crushing can proceed efficiently. Wet grinding with a ball mill is particularly preferred.

The ball mill is preferably performed under the conditions of a rotation speed of 30 to 400 rpm and a rotation time of 1 to 12 hours. Regarding this point, Non-Patent Document 2 describes that it takes 10 hours to atomize the GaNMn ₃ powder to a particle size of 3 to 4 μm and 35 hours to atomize it to a particle size of 1 μm or less by a ball mill. There is. On the other hand, the manufacturing method of the present invention is advantageous in terms of cost because the operating time of the ball mill required for micronization is significantly shorter than that of the conventional technique. If the number of rotations or the rotation time is too short, the manganese nitride may not be sufficiently atomized.
In the present invention, the manganese nitride raw material can be pulverized under predetermined conditions, preferably by a dry or wet pulverization method using a ball mill, to impart or maintain the function of negative thermal expansion to the obtained manganese nitride. ..

In the method for producing a manganese nitride of the present invention, the manganese nitride raw material may be put into a ball mill as it is and the manganese nitride raw material may be crushed, or a manganese nitride raw material to which an organic solvent is added may be added and crushed. May be. In the present invention, it is preferable to use an organic solvent from the viewpoint of effectively transmitting the energy of the powder. The type of organic solvent is not limited, but toluene, xylene, mesitylene, acetone, anhydrous ethanol, hexane, octane, ester (for example, ethylene glycol monomethyl ether), ether and the like are used. Among these organic solvents, those containing no oxygen atom in the molecule are preferably used.

The above-mentioned production method further includes a step of dispersing the manganese nitride fine particles in a liquid, allowing the particles to stand still, recovering the supernatant, and distilling and drying the supernatant to obtain purified manganese nitride. Is preferable. That is, by further applying such an operation to the manganese nitride after the micronization treatment, it is possible to classify the manganese nitride into a group of particles having a uniform particle size. As the liquid used at this time, water-based and organic solvent-based liquids can be widely applied.

The manganese nitride fine particles obtained by the above production method have a median diameter of 3 μm or less. Here, the median diameter is the volume frequency center particle size by the laser diffraction / scattering type particle size distribution evaluation method. In the particle size distribution measuring device based on the laser diffraction / scattering method, the particle size distribution is measured on a volume basis, and the particle size distribution on the number basis is calculated from the volume basis. The particle size distribution can be expressed by the volume frequency for each particle size. The median diameter D ₅₀ is the particle size at which the cumulative volume frequency is 50%, and the median diameter D ₉₀ is the particle size at which the cumulative volume frequency is 90%.

Specifically, the manganese nitride according to the present invention has a linear expansion coefficient α of -30 ppm / K or less in a temperature range of 250 to 450 K in a temperature range of at least ΔT = 30 K when the median diameter is 2 μm or less. .. Further, when the median diameter is 2 μm or less, it is more preferable that the linear expansion coefficient α has a negative thermal expansion property of −48 ppm / K or less. Further, the manganese nitride according to the present invention has a temperature range showing negative thermal expansion even when the median diameter is 1 μm or less.

Such manganese nitrides are not limited, but are preferably Mn, Ga, Zn, Cu, Ge, Sn, N, C, Fe, B, Si and In in at least a portion of their structure. A compound having one or more atoms selected from. In addition, N constituting manganese nitride may be defective. However, a preferred form of the manganese nitride of the present invention is a compound having a composition represented by the following general formula (1).
Mn _{3 + y} M ¹ _{1- (x + y)} M ² _x N _z … (1)

In the general formula (1), M ¹ is Ga, Zn or Cu, M ² is Ge or Sn, and 0 <x <1, −0.3 <y <1, 0 <z <1. It is 1. The composition represented by the general formula (1) is Mn ₃ Ga _0.9 Sn _0.1 N _0.9 (in the general formula (1), M ¹ is Ga and M ² is Sn, x = 0.1, y = 0. , Z = 0.9), Mn _3.1 Zn _0.5 Sn _0.4 N, (in general formula (1), M ¹ is Zn, M ² is Sn, x = 0.4, y = 0.1. , Z = 1), and Mn _3.27 Zn _0.45 Sn _0.28 N (in general formula (1), M ¹ is Zn, M ² is Sn, x = 0.28, y = 0.27, z. The form in which = 1) is particularly preferable.

The manganese nitride raw material used for producing the manganese nitride is a compound containing one or more atoms selected from Mn, Ga, Zn, Cu, Ge, Sn, N, C, Fe, B, Si and In. However, N constituting the manganese nitride raw material may be defective. For example, it may be a mixture composed of a plurality of components such as Mn _2N , Ga and Sn. Further, for example, a commercially available product such as Smartec (registered trademark) (manufactured by High Purity Chemical Laboratory Co., Ltd.), which is a Mn—Sn—Zn—N-based thermal expansion inhibitor, may be used. The manganese nitride raw material is usually an inverted perovskite type crystal. The manganese nitride produced from such a manganese nitride raw material usually has the same inverted perovskite type crystals as the manganese nitride raw material, but may change to an amorphous structure by pulverization.

According to the present invention, manganese nitride fine particles having excellent negative thermal expansion can be stably provided. Such a manganese nitride can be used, for example, by combining it with a resin having a positive expansion coefficient to form a mounting component such as a semiconductor device or an integrated circuit (IC), or a packing or sealing agent for a joint of a container. It can be used as a paste for heat sinks and their joint surfaces.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

[Example 1] Preparation of Mn ₃ Ga _0.9 Sn _0.1 N _0.9 particles Mn ₃ Ga _0.9 Sn _0.1 N _0.9 , which is a manganese nitride raw material, is prepared by a solid phase reaction method using Mn ₂ N, Ga and Sn as starting materials. did. The obtained Mn ₃ Ga _0.9 Sn _0.1 N _0.9 was pulverized in the air at room temperature for about 5 minutes using a mortar and pestle to obtain a crude powder. The crude powder was placed in an airtight pot together with a zirconia ball and acetone or absolute ethanol, and wet pulverized with a planetary ball mill (Letche PM100) for 2 hours to obtain a fine powder. The particle size distributions of both were evaluated by a laser light diffraction type particle size distribution meter (LA-950V2, HORIBA, Ltd.). The results are shown in FIG.
Before and after pulverization, the median diameter D ₅₀ decreased from 12.78 μm to 2.14 μm, and D ₉₀ decreased from 57.96 μm to 4.10 μm.

The negative thermal expansion is measured by the X-ray diffractometry, and the linear expansion coefficient α is -78.2 ppm / K in the temperature range of 340 to 360 K (ΔT = 20K) before crushing, and 320 to 360 K (ΔT) after crushing. In the temperature range of (= 40K), α changed to −49.6 ppm / K (FIG. 2). Such changes due to micronization are qualitatively consistent with the examples reported in the past, and the operating temperature range was extended to the lower side, and the slope of negative thermal expansion and the total volume change became smaller. However, the decrease in the total volume change is not large, and a sufficiently large negative thermal expansion is maintained. Rather, it can be said that the expansion of the operating temperature range by about 20 K is a preferable change as a thermal expansion inhibitor. This characteristic is, for example, the characteristic of a coarse powder of Smartec-M (Mn-Zn-Sn-N-based thermal expansion inhibitor; manufactured by High Purity Chemical Laboratory Co., Ltd.) (that is, the temperature is 293 to 338K (ΔT = 45K)). It is equal to or higher than α = -40 ppm / K).

As a result of electron microscope observation, when the median diameter D ₅₀ was about 2 μm, there was no particular change from the coarse powder, but when it was about 1 μm, lattice strain was observed. For example, according to Phys. Rev. Lett. 101 (2008) 205901, it is reported that the expansion of the operating temperature range of negative thermal expansion correlates with the strain of the local structure, and the origin of the change in physical properties due to micronization is investigated. The above is a suggestive result.

[Example 2]
<Preparation of manganese nitride>
Preparation Example 1
As a manganese nitride raw material, 3 kg each of Smartec-M (normal temperature negative expansion type) and Smartec-H (high temperature negative expansion type) (thermal expansion inhibitor; both manufactured by High Purity Chemical Laboratory Co., Ltd.) were used. The pulverization step was performed twice by a dry jet mill (single track jet mill FS-4 (Al ₂ O ₃ liner); manufactured by Seishin Co., Ltd.).

The particle size (median diameter) and negative thermal expansion of each of the obtained fine powders were measured. The results are shown in FIGS. 3 and 4.
The analysis / evaluation equipment used is as follows.
・ Laser diffraction / scattering type particle size distribution measuring device LA-920 (manufactured by HORIBA, Ltd.)
-Field emission scanning electron microscope (FE-SEM) JSM6700F (manufactured by JEOL Ltd.)
・ ICP-OES (Inductively coupled plasma emission spectrophotometer) ICPS-8100 (manufactured by Shimadzu Corporation)
・ Oxygen-nitrogen analyzer EMGA620WC (manufactured by HORIBA, Ltd.)

Preparation Example 2
200 g each of Smartec-M and Smartec-H were used, 80 to 150 mL of mesitylene was added to each of the raw materials, and the mixture was pulverized by a wet planetary ball mill (PM400; manufactured by Lecce).
The particle size and negative thermal expansion of each of the obtained fine powders were measured using the apparatus described in Preparation Example 1. The results are shown in FIGS. 5 and 6.

Preparation Example 3
3 kg each of Smartec-M and Smartec-H were used and pulverized using a dry jet mill + wind power classifier (Super Jet Mill SJ-500 + TC-15; manufactured by Nisshin Engineering Co., Ltd.).
The particle size and negative thermal expansion of the obtained fine powder were measured using the apparatus described in Preparation Example 1. The results are shown in FIGS. 7 and 8.

<Evaluation>
In terms of miniaturization median diameter, the wet planetary ball mill is superior to the jet mill, but it was found that the jet mill can obtain particles with less sharpness, more roundness, and an aspect ratio close to 1. Such particles are advantageous for future insulating coatings. In addition, jet mill crushing tended to have a smaller particle size distribution and less crushed residue than wet planetary ball mill crushing. Therefore, it can be said that a pulverization method combining jet mill pulverization and wet ball mill pulverization is effective.

Chemical composition In Preparation Example 1 using a dry jet mill for pulverizing the manganese nitride raw material, it was found that the amounts of Fe and Ni increased before and after pulverization in both Smartec-M and Smartec-H.
In Preparation Example 2 using a wet planetary ball mill for pulverizing the manganese nitride raw material, the amount of Zr increased before and after pulverization in both Smartec-M and Smartec-H. The reason for this is considered to be that the crushing pot and the media are made of zirconia.
In Preparation Example 3 using a dry jet mill + a wind classifier for pulverizing the manganese nitride raw material, there was almost no change in the chemical composition before and after pulverization in both Smartec-M and Smartec-H.

Negative thermal expansion With respect to Smartec-M, thermal expansion was evaluated at three points: raw material: M180 (coarse powder), a) dry jet mill crushed product: M20, b) wet planetary ball mill crushed product: M10. The linear thermal expansion of the sample obtained by sintering the manganese nitride after the fine powder by discharge plasma sintering was measured by the laser interferometry. As a result, it was confirmed that as the particle size became smaller, the operating temperature range expanded toward the low temperature side, and as a result, the slope of negative thermal expansion became smaller (FIG. 9). In M10, the coefficient of linear expansion α = -30 ppm / K at 270 to 330 K (ΔT = 60 K), which was not inferior to the characteristics reported in the bulk body / coarse powder (for example, Mn _3.27 Zn _0.45 Sn _0.28 N).

The material obtained by mixing and compounding the manganese nitride according to the present invention with a resin having a positive expansion coefficient is, for example, a mounting component such as a semiconductor device or an integrated circuit (IC), or a packing or a sealing agent for a joint of a container. , Or a paste used for heat sinks and their joint surfaces.

Claims (1)

A group of manganese nitride fine particles having a median diameter of 2 μm or less, a linear expansion coefficient α of −48 ppm / K or less , and having a composition represented by the general formula (1) in at least a part of the structure .
Mn _{3 + y} M ¹ _{1- (x + y)} M ² _x N _z … (1)
(In the general formula (1), M ¹ is Ga, Zn or Cu, M ² is Ge or Sn, and 0 <x <1, −0.3 <y <1, 0 <z <1. .1)

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