KR20170003259A

KR20170003259A - Sintered body, composition for sintering silicon nitride and preparation method of sintered body

Info

Publication number: KR20170003259A
Application number: KR1020150093682A
Authority: KR
Inventors: 도환수; 고정민; 이성수
Original assignee: 주식회사 엘지화학
Priority date: 2015-06-30
Filing date: 2015-06-30
Publication date: 2017-01-09
Also published as: KR101959485B1

Abstract

The present invention relates to a sintered body, a composition for sintering silicon nitride, and a method for producing the sintered body. According to the present invention, the sintered body can be used for sintering silicon nitride-based materials with a stable phase using specific transition metal when sintering the silicon nitride-based sintered body. In addition, it is also possible to produce the silicon nitride-based sintered body with increased heat conductivity as well as radiating materials for circuit substrate using the same.

Description

TECHNICAL FIELD The present invention relates to a sintered body, a composition for sintering silicon nitride, and a method for manufacturing a sintered body,

The present invention relates to a sintered body, a composition for sintering silicon nitride, and a method for producing a sintered body.

BACKGROUND ART A power semiconductor device (hereinafter referred to as a power device) is mainly used for an inverter or a circuit, and refers to a semiconductor device necessary for switching or changing power, and controlling a motor. Since the introduction of the Thyristor in 1957, the power electronics industry has also made remarkable progress with the development of power devices, power switching and control using them, and the power electronics industry using them. In recent years, technological innovation and technology dissemination have been actively promoted to transform the earth into a recycling society that reuses resources and energy. As a result, Power Electronics and its key component, Power Devices, play an increasingly important role It is becoming.

Typically, the power used in a power device is more than a few hundred amperes, and since the voltage is also high in the range of several hundred volts, the temperature of the heat generated from the semiconductor is also very high. Therefore, deterioration of the device, deterioration of performance, malfunction and breakage may occur due to such heat. Effective heat release from power devices is required to prevent and overcome this phenomenon. Since the ceramics material having electric insulation and high thermal conductivity has a very excellent heat radiation function for rapidly transferring and diffusing heat generated in the power device, it is preferable to use a heat dissipation member (for example, heat sinks and so on. The ceramic material is excellent in thermal and mechanical properties such as high strength and high heat resistance, but has a limited application because its ovoidity, hard workability and fracture toughness are remarkably lower than those of other materials.

On the other hand, silicon nitride generally has a flexural strength of 1,000 to 1,400 MPa, which is the best among the ceramics, and has a low coefficient of thermal expansion of 3.2 × 10 ^-6 / K. Also, it has a density of about 3.2 g / cm ³ , a thermal conductivity in the range of 30 to 178 W / (m · K), a thermal shock resistance in the range of 800 to 1000 K, And thus it is widely used as a new heat-dissipating material. Therefore, there is a growing demand for a substrate material that uses a silicon nitride material as a circuit substrate material and has an improved thermal conductivity property to emit high-temperature heat generated in a power device, among ceramics having excellent thermal conductivity. For example, it is known to use a silicon nitride-based sintered body on an insulating circuit board used in a power semiconductor module for mounting a semiconductor that operates with a large power. In such an insulating circuit board, it is necessary to diffuse and dissipate heat emitted from the power semiconductor have.

Silicon Nitride (Si ₃ N ₄ ) is an ovoid-forming material whose self-diffusion is difficult due to strong covalent bonds and whose sintering temperature is limited due to thermal decomposition at high temperatures. Accordingly, in the case of producing a silicon nitride sintered body, it is generally known to add an oxide such as Y ₂ O ₃ , Al ₂ O ₃ , MgO or the like as a sintering agent to sinter the liquid phase.

(Patent Document 1) KR2007-0103330 A

Embodiments of the present application provide a silicon nitride sintered body having improved thermal conductivity, a composition for sintering silicon nitride, and a method of manufacturing a sintered body.

One embodiment of the present application provides a sintered body. According to the exemplary sintered body of the present application, it is possible to sinter a stable phase of silicon nitride material by adding a specific transition metal at the time of manufacturing the sintered silicon nitride material. In addition, the oxide of the specific transition metal Thereby reducing the content of solid solution oxygen in the silicon nitride crystal. Thus, the silicon nitride sintered body having improved thermal conductivity can be provided.

1 is a cross-sectional view of a sintered body 1 of the present application.

In one embodiment, as in Fig. 1, the sintered body 1 of the present application comprises an amorphous region 11 and a crystalline region 12. As used herein, the term " crystalline region " means a region where crystallization occurs or crystal grains are observed in the sintered body 1, and " amorphous region " means a region where crystallization does not occur, It means the area that is not observed. In the above, " crystal grains are observed " means that at least one crystal grain is observed when the specimen is observed at 4000 times magnification by a transmission electron microscope.

In one example, the amorphous region 11 comprises SiO ₂ , and the crystalline region 12 is comprised of? -Si ₃ N ₄ Lt; / RTI > Silicon nitride (Si ₃ N ₄ ) is a low-temperature type α-Si ₃ N ₄ belonging to the hexagonal system Phase and high temperature type β-Si ₃ N ₄ Phase is in a stable state and is a homogeneous or higher-quality material, and at a temperature of 1400 to 1600 ° C, α-Si ₃ N ₄ The phase is composed of acicular β-Si ₃ N ₄ Phase transformation occurs. In one example, the phase transition is caused by a dissolution and re-precipitation process in which α-Si ₃ N ₄ melts into a liquid phase formed during liquid-phase sintering and is precipitated as thermodynamically stable β-Si ₃ N ₄ . The SiO ₂ is silicon nitride, a low-temperature before sintering, that is α-Si ₃ N as components present in the _four surfaces, the SiO ₂ and silicon nitride in the sintering process is the formation of eutectic liquid phase, and then sintering the SiO ₂ is the sintered body (1 ), And the? -Si ₃ N ₄ is present in the amorphous region (11) of? -Si ₃ N ₄ Phase, and the? -Si ₃ N ₄ Phase is contained in the crystalline region 12 of the sintered body 1. The thermal conductivity of the silicon nitride sintered body 1 is present on the surface of silicon nitride and largely depends on the SiO ₂ forming the eutectic liquid phase. On the other hand, a commercially available silicon nitride powder contains a small amount of oxygen as an impurity due to oxidation of the particle surface. The impurity, oxygen, can be transferred and solidified into the crystalline region 12 of the silicon nitride-based sintered body 1 during sintering of the silicon nitride powder. For example, when the α-Si ₃ N ₄ particles are dissolved in the liquid phase and re-precipitated in the sintering process of silicon nitride, the impurity oxygen is not contained in the precipitated β-Si ₃ N ₄ crystal grains, But if the oxygen is contained and remains in the β-Si ₃ N ₄ crystal grains, the dissolved oxygen may cause phonon scattering, which may interfere with the conduction of heat . Therefore, in order to produce the silicon nitride sintered body 1 having excellent heat conduction characteristics, it is necessary to lower the content of the dissolved oxygen in the crystalline region 12 of the sintered body 1.

In one embodiment, the amorphous region 11 comprises at least one selected from the group consisting of oxides of the transition metal. In one example, the electronegativity of the transition metal is from 1.23 to less than 1.9, such as from 1.3 to 1.7, from 1.3 to 1.66 or from 1.5 to 1.6, and the transition metal is from 600 to 730 kJ / mol, For example, it may have a primary ionization energy of 630 to 730 kJ / mol, 640 to 700 kJ / mol or 640 to 660 kJ / mol. The transition metal having the above-described range of electronegativity and primary ionization energy is an oxygen gettering material for removing the dissolved oxygen contained in the silicon nitride powder in the sintering process, The solid solution of oxygen in the sintered body 1 can be lowered as the oxides are contained in the amorphous region 11 at the beginning of the silicon nitride sintering reaction, It is possible to solve the problem that the thermal conductivity characteristic due to the generated phonon scattering is reduced. In addition, for example, when the electronegativity and the primary ionization energy are too small, the transition metal characteristic is lost and the characteristics are close to those of the alkali metal or alkaline earth metal. Accordingly, the reactivity becomes very high, And the sintering assistant may occur. If the amount is too large, the reactivity with oxygen is low and it is difficult to perform a role as an oxygen getter material. Therefore, a transition metal having the above-described range of electronegativity and primary ionization energy When used, it is possible to efficiently remove the dissolved oxygen. The term " transition metal " as used herein in the sense of " transition elements " is used herein to refer to elements belonging to Groups 3 to 12 in the periodic table, including the incomplete d, f orbitals Element. The term " electronegativity " as used herein refers to an intensity of a relative attracting force that pulls a pair of electrons forming a covalent bond. In the present specification, the term " electronegativity " is defined according to the value of the electronegativity proposed by LC Pauling in 1932 do. The term " primary ionization energy " refers to the energy required to take one electron out of a neutral or neutral molecule in a ground state and completely separate it into a single cation and a free electron.

Examples of the transition metal having the above-mentioned range of electronegativity and primary ionization energy are scandium, titanium, vanadium, chromium, manganese, zirconium, niobium, hafnium or tantalum, Or a mixture of two or more of them may be used, but the present invention is not limited thereto.

The melting point of the transition metal may be from 1600 캜 to 2500 캜, for example, from 1650 캜 to 2500 캜. The transition metal having such a melting point has a high reactivity with oxygen at a low temperature. Accordingly, the oxide of the transition metal is formed by bonding with oxygen preferentially at a low temperature at the time of sintering so that the content of dissolved oxygen in the sintered body 1 Can be reduced.

In one example, the transition metal may be a compound of Group 4 to Group 5 of the periodic table. The atomic weight of the transition metal may be in the range of 45 to 95. For example, the transition metal may be titanium, vanadium, zirconium or niobium, and preferably titanium or niobium may be used, but the present invention is not limited thereto.

In one embodiment, the amorphous region 11 may further comprise the non-oxidized transition metal in addition to the oxide of the transition metal.

The content of the transition metal may be included in an amount of 0.5 to 2 parts by weight based on the total amount of the components in the sintered body 1, and the oxygen gettering effect of the dissolved oxygen in the silicon nitride particles may be realized in the above- And the thermal conductivity of the silicon nitride sintered body 1 can be improved by removing the dissolved oxygen

In one embodiment, the amorphous region 11 may further comprise a sintering agent. Silicon Nitride (Si ₃ N ₄ ) is an ovoid-forming material which is difficult to self-diffusion due to strong covalent bonds and is limited in sintering temperature due to pyrolysis at high temperatures. In order to easily produce a liquid phase even at a low temperature , And can be further included in the sintering process. Accordingly, the sintering property of the silicon nitride-based sintered body 1 can be improved. After sintering, the sintering aids may be present in the amorphous region 11.

Wherein the sintering aid is selected from the group consisting of aluminum (Al), gadolinium (Gd), holmium (Ho), ytterbium (Yb), erbium (Er), dysprosium (Dy), yttrium (Y), and magnesium For example, a rare earth element oxide such as Y ₂ O ₃ , Gd ₂ O Ho ₂ O ₃ Er ₂ O ₃ , Yb ₂ O _3, or Dy ₂ O _3, or a rare earth element oxide such as Al ₂ O ₃ Or a metal oxide such as MgO may be used. Preferably, Y ₂ O ₃ , Al ₂ O _3, MgO, or the like can be used, but it is not limited thereto.

The content of the sintering auxiliary agent is 1 to 15 parts by weight, for example, 1 to 3 parts by weight, 5 to 15 parts by weight, 2 to 7 parts by weight or 2 to 5 parts by weight based on the total components in the sintered body 1 And in the content range of the above-mentioned range, a sufficient liquid phase can be formed to fill the spaces between the silicon nitride crystal grains in the silicon nitride sintering. If the content of the sintering aid is too large, the liquid quality region becomes too thick, and the thermal conductivity of the silicon nitride sintered body 1 may be lowered.

In addition, the sintered body 1 of the present application can have an appropriate range of density depending on the inclusion of the specific transition element, so that the content of SiO _{2 in} the amorphous region 11 per unit volume decreases, It is possible to solve the problem that the thermal conductivity is reduced due to SiO ₂ present in the region 11. [ In one example, the density of the sintered body 1 can be 3.240 g / cm ³ to 3.265 g / cm ^3, e.g., 3.245 g / cm ³ to 3.265 g / cm ³ or 3.247 g / cm ³ to 3.263 g / cm ^3, preferably, 3.249 g / cm ³ To 3.261 g / cm < ³ >, but is not limited thereto. The thermal conductivity of the sintered body 1 can be kept excellent in the density range of the above-mentioned range.

In one example, the sintered body 1 having a density in the above-mentioned range has excellent thermal conductivity, for example, at least 50 W / (m · K) at 25 ° C. and 45 W / (m · K ) Or higher, a thermal conductivity of at least 42 W / (mK) at 100 ° C, at least 40 W / (mK) at 150 ° C, or at least 30 W / (mK) at 200 ° C.

Another embodiment of the present application provides a composition for sintering silicon nitride. Exemplary compositions for sintering silicon nitride of the present application include a specific transition metal. Accordingly, it is possible to sinter a stable phase of silicon nitride material by using the composition for sintering silicon nitride of the present application, and also to provide a silicon nitride sintered body having improved thermal conductivity 1). &Lt; / RTI >

The composition comprises a transition metal and in one example the electronegativity of the transition metal is less than 1.23 to less than 1.9, for example 1.3 to 1.7, 1.3 to 1.66 or 1.5 to 1.6, To 730 kJ / mol, for example, 630 to 730 kJ / mol, 640 to 700 kJ / mol or 640 to 660 kJ / mol. The transition metal having the above range of electronegativity and primary ionization energy is an oxygen gettering material for removing the dissolved oxygen contained in the silicon nitride powder during the sintering process, It is possible to lower the solute oxygen content in the sintered body 1 as the oxides are contained in the amorphous region 11 in the initial stage of the silicon nitride sintering reaction and thereby the solute oxygen The problem that the thermal conduction characteristics due to phonon scattering is reduced can be solved. In addition, for example, when the electronegativity and the primary ionization energy are too small, the transition metal characteristic is lost and the characteristics are close to those of the alkali metal or alkaline earth metal. Accordingly, the reactivity becomes very high, And the sintering assistant may occur. If the amount is too large, the reactivity with oxygen is low and it is difficult to perform a role as an oxygen getter material. Therefore, a transition metal having the above-described range of electronegativity and primary ionization energy When used, it is possible to efficiently remove the dissolved oxygen.

Also, the melting point of the transition metal may be 1600 ° C to 2500 ° C, for example, 1650 ° C to 2500 ° C. The transition metal having such a melting point has a high reactivity with oxygen at a low temperature. Accordingly, the oxide of the transition metal is formed by bonding with oxygen preferentially at a low temperature at the time of sintering so that the content of dissolved oxygen in the sintered body 1 Can be reduced.

In one example, the transition metal may be a compound of Group 4 to Group 5 of the periodic table. The atomic weight of the transition metal may be in the range of 45 to 95. For example, titanium, vanadium, zirconium or niobium may be exemplified, and titanium or niobium may be preferably used, but the present invention is not limited thereto.

The content of the transition metal may be included in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the composition. In the range of the above-mentioned range, the oxygen gettering effect of the dissolved oxygen in the silicon nitride particles can be realized , And the thermal conductivity of the silicon nitride sintered body (1) can be improved by removing the dissolved oxygen.

In one embodiment, the composition for silicon nitride sintering may further comprise a sintering agent. Silicon Nitride (Si ₃ N ₄ ) is an ovoid-forming material which is difficult to self-diffusion due to strong covalent bonds and is limited in sintering temperature due to pyrolysis at high temperatures. In order to easily produce a liquid phase even at a low temperature , And can be further included in the composition. Thus, sintering property of the silicon nitride-based sintered body 1 can be improved.

Wherein the sintering aid is selected from the group consisting of aluminum (Al), gadolinium (Gd), holmium (Ho), ytterbium (Yb), erbium (Er), dysprosium (Dy), yttrium (Y), magnesium For example, a rare earth element oxide such as Y ₂ O ₃ , Gd ₂ O Ho ₂ O ₃ Er ₂ O ₃ , Yb ₂ O _3, or Dy ₂ O _3, or a rare earth element oxide such as Al ₂ O ₃ Or a metal oxide such as MgO may be used. Preferably, Y ₂ O ₃ , Al ₂ O _3, MgO, or the like can be used, but it is not limited thereto.

The content of the sintering auxiliary agent is 1 to 15 parts by weight, for example, 1 to 3 parts by weight, 5 to 15 parts by weight, 2 to 7 parts by weight or 2 to 5 parts by weight based on the total components in the sintered body 1 And in the content range of the above-mentioned range, a sufficient liquid phase can be formed to fill the spaces between the silicon nitride crystal grains in the silicon nitride sintering. If the content of the sintering aid is too large, the liquid quality region becomes too thick, and the thermal conductivity of the silicon nitride sintered body 1 may be lowered

Another embodiment of the present application provides a method of manufacturing the above-described sintered body (1).

Exemplary methods of the present application include the steps of: molding a composition comprising a transition metal having an electronegativity of less than 1.23 and less than 1.9 and a primary ionization energy of 600 to 730 kJ / mol to produce a molded article; And sintering the molded article. The content of the transition metal is the same as that described for the sintered product (1) and the sintering composition, and therefore will not be described.

The step of producing the molded article is a step of molding the composition into a molded article. In one example, the step of producing the molded article includes ball-milling and pulverizing the mixture, And molding.

The ball-milling in the step of ball-milling and crushing may be performed, for example, using a cylindrical ball mill or a vibrating mill apparatus, and the step of shaping into the film or sheet shape may be performed by a tape casting apparatus . In one embodiment, ball-milling and milling and shaping into a film or sheet shape may be performed simultaneously by an in-situ process.

The step of sintering the molded article is a step of sintering the molded article produced in the step of manufacturing the molded article, wherein the molded article is maintained under vacuum at a temperature of 1500 to 1800 캜 and a pressure of 20 to 40 MPa for 5 to 20 minutes Lt; / RTI >

The sintered product 1 of the present application can be applied to various application fields and, for example, due to its excellent thermal conductivity, various sorts of substrates such as a power semiconductor circuit board or a substrate for a multi-chip module, a heat conductive plate for a peltiert element, A heat sink for a heat generating element of an electronic component such as a heat sink.

For example, when the silicon nitride sintered body 1 of the present application is used for a substrate for a semiconductor device, cracks do not easily occur on the substrate even if a repeated thermal cycle is performed according to the operation of the semiconductor device, So that the substrate for a semiconductor device having excellent high-temperature reliability can be provided.

When the silicon nitride sintered body 1 having excellent thermal conductivity is used in the electrothermal substrate for a Peltier element, cracks do not occur in the substrate even if a repetitive thermal cycle accompanied by a change in the polarity of the voltage applied to the Peltier element occurs, Thus, it is possible to provide a substrate having high high temperature reliability.

The silicon nitride-based sintered body 1 of the present application can be widely used for structural members requiring heat resistance such as heat shock resistance and heat-resistance fatigue in addition to members for electronic parts. Examples of the structural member include various heat exchanger parts, heat pipe parts, heater tubes used for molten metal such as aluminum and zinc, Stokes, die cast sleeves, Ladle, and a thermocouple protection tube. It is also applicable to sink rolls, support rolls, bearings, shafts, and the like, which are used in molten metal plating lines such as aluminum and zinc as materials having a high resistance to cracking against abrupt heating and cooling . In addition, in the field of processing steel or non-ferrous metals, when used in rolling rolls, squeezing rolls, guide rolls, line drawing dies, tool chips and the like, excellent thermal fatigue resistance and thermal shock resistance, There is an advantage that heat dissipation is good, wear is small, and thermal stress cracks do not easily occur.

The silicon nitride sintered body 1 of the present application can also be applied to a sputter target material. For example, the silicon nitride sintered body 1 can be formed into an electric insulating film used for an MR head, a GMR head, a TMR head, It can be suitably used for forming a wear-resistant film used for a thermal head or the like. The coating obtained by sputtering has inherently high thermal conductivity and a high electric insulation withstand voltage. Therefore, the electrical insulating film for MR head, GMR head or TMR head formed from the sputter target has thermal conductivity and high withstand voltage It is possible to make the insulating film thinner. In addition, since the silicon nitride film for a thermal recording head formed from this sputter target has excellent abrasion resistance and thermal conductivity, the printing speed can be increased.

Fig. 2 is a plan view (a) schematically showing a circuit board to which the sintered body 1 of the present application is applied, Fig. 2 (b) is a sectional view taken along the line A- Fig.

2, the exemplary circuit board 100 includes circuit members 120a and 120b on the first main surface side of the support substrate 110 made of the sintered nitrile nitride substrate 1 of the present application, The circuit members 120a and 120b and the heat radiating member 130 are bonded to the supporting substrate 110 by the bonding layers 140a and 140b, respectively, And 140b.

The supporting substrate 110 made of the sintered silicon nitride material 1 of the present invention constituting the circuit board 100 may be of a flat plate type and may have a length of 20 mm to 200 mm , And the width (Y direction in FIG. 2) may be 10 mm to 120 mm, but is not limited thereto. The thickness of the support substrate 110 may vary depending on the application, and may be 0.2 mm to 1.0 mm in consideration of the insulation resistance and durability.

The circuit member 120a constituting the circuit board 100 may have a length (X direction in FIG. 2) of 15 mm to 155 mm, for example, and a width (Y direction in FIG. 2) mm to 100 mm, but is not limited thereto. 2) may be 1 mm to 10 mm, and the width (Y direction in Fig. 2) may be 8 mm to 100 mm. However, the circuit member 120b may have a length But is not limited to. The thickness of the circuit members 120a and 120b can be determined by the magnitude of the current flowing through the circuit members 120a and 120b and the amount of heat generated by electronic components (not shown) mounted on the circuit members 120a and 120b, But may be, for example, from 0.5 mm to 5 mm.

The heat dissipation member 130 included in the circuit board 100 has a function of emitting heat from a heat-generating electronic component (not shown). For example, when the length (X direction in FIG. 2) mm to 190 mm, and the width (Y direction in FIG. 2) may be 8 mm to 100 mm, and the thickness may be 0.5 mm to 5 mm, but is not limited thereto.

3 is a plan view (a) of an electronic device to which the sintered body 1 of the present application is applied, (b) is a cross-sectional view taken along the line D-D ' Fig.

3, the exemplary electronic device S may be one in which electronic components 160 and 170 such as one or more semiconductor devices are mounted on the circuit member 120 of the circuit board 100, The electronic components 160 and 170 may be electrically connected to each other by a conductor (not shown). That is, the electronic device S includes electronic components 160 and 170 mounted on the circuit member 120 of the circuit board 100, and even if the electronic components 160 and 170 repeatedly generate heat, The electronic device S having high durability can be provided since the substrate 110, the circuit member 120, and the heat radiation member 130 are not easily peeled off.

5 may be, for example, a length (X direction in FIG. 5) of 4 mm to 40 mm or less, and the widths (Y in FIG. 5) of the exemplary circuit member 120 and the heat radiation member 130 Direction) may be from 5 mm to 50 mm, and the thickness may be from 0.5 mm to 5 mm, but is not limited thereto.

5, the circuit member 120 and the heat radiation member 130 may be arranged in a plurality of rows and a plurality of columns, respectively, in a plane. Thus, the circuit member 120 and the heat radiation member 130 Are arranged in a plurality of rows and a plurality of rows in a plane so that the stress generated in the supporting substrate 110 is easily dispersed when the circuit member 120 and the heat radiation member 130 are bonded to the supporting substrate 110 The occurrence of warping of the supporting substrate 110 can be reduced. The circuit member 120 and the heat radiating member 130 may be arranged at regular intervals in a plurality of rows and a plurality of rows, respectively, as shown in Fig.

According to the sintered body of the present invention, it is possible to sinter a silicon nitride material having a stable phase by using a specific transition metal at the time of manufacturing a silicon nitride sintered body, and to provide a silicon nitride sintered body having improved thermal conductivity and a heat dissipation material of a circuit board using the sintered body .

1 is a cross-sectional view of an exemplary sintered body of the present application.
2 is a plan view schematically showing a circuit board to which the sintered body of the present application is applied.
3 is a plan view showing an exemplary electronic device to which the sintered body of the present application is applied.
4 is a graph showing the results of XRD analysis of the phase change of the silicon nitride-based sintered body manufactured in Examples and Comparative Examples.

Hereinafter, the present application will be described in detail by way of examples and comparative examples of the present application, but the scope of the present application is not limited by the following examples.

Preparation of Silicon Nitride Sintered Body

Example One

3.68 g of? -Si ₃ N ₄ powder, 0.2 g of yttrium oxide (Y ₂ O ₃ ) and 0.8 g of magnesium oxide (MgO) as sintering aids, and 0.1 g of magnesium oxide (MgO) as a transition metal were mixed to prepare a sintered body of silicon nitride (Si ₃ N ₄ ) (Si ₃ N ₄ : Y ₂ O ₃ : MgO: TM (Nb) = 92 wt%: 5, Nb, atomic weight 92.9, primary ionization energy 652 kJ / mol, electronegativity 1.6, melting point 2468 ° C) wt%: 2 wt%: 1 wt%) were mixed to prepare a mixed powder composition of Si ₃ N ₄ and weighed in a 4 g batch. The weighed powder was mixed in an alumina mortar. Thereafter, the mixed powder was charged into a plastic container of 250 ml and dry ball-milled with 200 g of zirconia (ZrO ₂ ) balls (? = 5 mm) for 24 hours. The milled powder was charged into a graphite mold for sintering (Φ = 20 mm), and then sintered in vacuum at a pressure of 30 MPa at a temperature of 1600 ° C. for 5 minutes to produce a silicon nitride sintered body.

Example 2

A silicon nitride sintered body was produced in the same manner as in Example 1, except that titanium (Ti, atomic weight: 47.9, primary ionization energy: 658 kJ / mol, electronegativity: 1.54, melting point: 1660 ° C) was used instead of niobium as a transition metal .

Comparative Example One

3.72 g of? -Si ₃ N ₄ powder, 0.2 g of yttrium oxide (Y ₂ O ₃ ) and 0.08 g of magnesium oxide (MgO) (Si ₃ N ₄ : Y ₂ O ₃ : MgO : 93 wt%: 5 wt%: 2 wt%) were mixed to prepare a Si ₃ N ₄ mixed powder, and a silicon nitride sintered body was produced in the same manner as in Example 1.

Comparative Example 2

A silicon nitride sintered body was produced in the same manner as in Example 1, except that tungsten (W, atomic weight 183.8, primary ionization energy 759 kJ / mol, electronegativity 2.36, melting point 3407 캜) was used as a transition metal instead of niobium .

Experimental Example

One. XRD Of the silicon nitride-based sintered body Phase change analysis

The phase change of the silicon nitride-based sintered body produced in the above Examples and Comparative Examples was analyzed using XRD. The results are shown in FIG.

In general, Si ₃ N ₄ is known to undergo phase transition from? Phase to? Phase in the temperature range of 1400 to 1600 占 폚, and most of the sintered bodies of Examples and Comparative Examples are phase transition from? Phase to? Phase Respectively. In addition, the peaks of MgO and Y ₂ O ₃ added as the sintering aid did not appear, and the peak of the added transition metal or the peak of the related corrosion was not observed. Thus, it was confirmed that stable phase transition and sintered body were produced.

That is, phase analysis of the silicon nitride-based sintered body produced in the examples and the comparative examples showed that the silicon nitride-based sintered body of the comparative example in which only MgO and Y ₂ O _{3, which} are general sintering aids, and the sintering composition containing the specific transition metal The silicon nitride-based sintered bodies in the examples used all had the same? -Si ₃ N ₄ Phase. From this, it is confirmed that a stable phase is formed.

2. Analysis of density change of silicon nitride sintered body

The densities of the sintered bodies produced in Examples and Comparative Examples were measured. Specifically, the density was measured using the Archimedes method. The results are shown in Table 1 below.

Furtherance Density (g / cm ³⁾ Example 1 Si ₃ N ₄ + Nb (1 wt%) 3.261 Example 2 Si ₃ N ₄ + Ti (1 wt%) 3.249 Comparative Example 1 Si ₃ N ₄ 3.237 Comparative Example 2 Si ₃ N ₄ + W (1 wt%) 3.267

Si ₃ N ₄ has a theoretical density of 3.19 to 3.20 g / cm ^3, but is known to exhibit, as shown in Table 1, while the average density of the transition metal silicon nitride sintered body is not added, is of 3.24g / cm ^3, a titanium the average density of added silicon nitride sintered body has an average density of 3.25g / cm ^3, the average density of the silicon nitride sintered body of niobium is added to the 3.26g / cm ^3, silicon nitride sintered bodies of the tungsten is added as about 3.27g / cm ³ , It can be confirmed that the sintered body of the present application has a value higher than the theoretical density value. The reason why the density value is higher than the theoretical density value is because the transition metal is contained in the composition for sintering. That is, the atomic number of titanium is 22, the atomic number of niobium is 41, and the atomic number of tungsten is 74 in the periodic table, and the density tends to increase as the atomic number of the added transition metal increases, This is because the density increases due to the increase in the atomic weight of the metal.

In other words, the sintered sintered body obtained by adding a specific transition metal to Si ₃ N ₄ has a result exceeding the known theoretical density, and the density of the silicon nitride-based sintered body to which the transition metal is added increases with the atomic number of the added transition metal And it is analyzed that it shows normal behavior increasing with increasing

3. Measurement of Thermal Conductivity of Silicon Nitride Sintered Body

The thermal diffusivity of the sintered bodies prepared in Examples and Comparative Examples was measured using a laser pulse method from room temperature to 200 ° C. The thermal conductivities of the sintered bodies prepared in Examples and Comparative Examples were calculated by the following methods.

In physics, thermal conductivity is defined as the numerical value representing the heat transfer of a material, expressed in k, and the unit is W / (m · K). The method of measuring the thermal conductivity can be classified into a hot wire method, a guarded heat flow method, a heated hot plate method, and a laser pulse method according to a measurement method. The thermal conductivity is calculated by the following equation (1).

[Formula 1]

In Equation 1, Q represents the heat flow (W), A represents the area (m2) of the sample, L represents the thickness (m) of the sample and ΔT represents the temperature difference (° C or K).

Among the methods of measuring thermal conductivity, the laser pulse method is known as a method of measuring thermal diffusivity. When the laser causes the energy pulse to heat the bottom surface of one side of the sample, the temperature of the upper side of the sample opposite to the sample rises by a given energy over time. At this time, if the thermal diffusivity of the sample is large, the amount of energy and the time to reach the opposite side is faster, and when the one-dimensional and adiabatic state is assumed, the thermal diffusivity calculated from the temperature increase is calculated by the following equation (2).

[Formula 2]

In equation 2 a is thermal diffusivity (thermal diffusivity), d is the time when the signal (signal) of the thickness of the sample, t _1/2 is dwirak delta function (Dirac delta function) is half the maximum value (maximum) .

Using the thermal diffusivity of the sample calculated according to Equation 2, the density of the measured sample, and the specific heat of the generally known sample, the thermal conductivity was calculated according to Equation 3 below.

[Formula 3]

In equation 3, K _T represents the degree (W / m · K) thermal conductivity, α denotes a sample thermal diffusivity ^{(m · m 2 / s)} , ρ denotes the density of the sample, and C _p is the sample Specific heat coefficient (J / g · K).

The results of the calculated thermal conductivity are shown in Table 2 below.

Furtherance Thermal conductivity (W / m · K) 25 ℃ 50 ℃ 100 ℃ 150 ℃ 200 ℃ Example 1 Si ₃ N ₄ + Nb (1 wt%) 54.871 50.682 46.679 41.394 39.960 Example 2 Si ₃ N ₄ + Ti (1 wt%) 52.401 48.733 42.684 40.031 33.526 Comparative Example 1 Si ₃ N ₄ 45.520 41.163 37.415 32.074 27.686 Comparative Example 2 Si ₃ N ₄ + W (1 wt%) 42.287 37.791 32.049 29.064 22.651

As can be seen from Table 2, the thermal conductivity of the sintered silicon nitride sintered using a specific transition metal is higher than that of the sintered body using general sintering additives MgO and Y ₂ O ₃ , Can be confirmed.

1: sintered body
11: amorphous region
12: crystalline region
100: circuit board
110: Support substrate (silicon nitride sintered body)
120a, 120b: circuit member
130:
140a, 140b: bonding layer
150a, 150b:
160, 170: Electronic parts
S: Electronic device

Claims

An amorphous region comprising SiO ₂ and at least one selected from the group consisting of oxides of transition metals having an electronegativity of less than 1.23 to less than 1.9 and a primary ionization energy of 600 to 730 kJ / mol; And a crystalline region comprising a beta -Si ₃ N ₄ phase.

The sintered body according to claim 1, wherein the transition metal is a compound of Group 4 to Group 5 of the periodic table.

The sintered body according to claim 1, wherein the transition metal has a melting point of 1600 캜 to 2500 캜.

The sintered body according to claim 1, wherein the atomic weight of the transition metal is 45 to 95.

The sintered body according to claim 1, wherein the transition metal comprises at least one selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, zirconium, niobium, hafnium and tantalum.

The sintered body of claim 1, wherein the amorphous region further comprises a transition metal having an electronegativity of less than 1.23 and less than 1.9 and a primary ionization energy of 600 to 730 kJ / mol.

The sintered body according to claim 1, wherein the amorphous region further comprises a sintering auxiliary agent.

The method according to claim 1, wherein the sintering aid is selected from the group consisting of Al, Gd, Ho, Yb, Er, Dy, Y, Wherein the sintered body contains at least one oxide selected from the group consisting of titanium oxide and titanium oxide.

The sintered body according to claim 1, wherein the density is 3.240 to 3.265 g / cm ³ .

The sintered body according to claim 1, wherein the thermal conductivity measured at 25 캜 is 50 W / (m K) or more.

A transition metal having an electronegativity of less than 1.23 to less than 1.9 and a primary ionization energy of 600 to 730 kJ / mol.

12. The composition for sintering silicon nitride according to claim 11, wherein the transition metal is a compound of Group 4 to Group 5 of the periodic table.

The composition for sintering silicon nitride according to claim 11, wherein the transition metal has a melting point of 1600 캜 to 2500 캜.

The composition for sintering silicon nitride according to claim 11, wherein the atomic weight of the transition metal is 45 to 95.

The composition for sintering silicon nitride according to claim 11, wherein the transition metal compound comprises at least one selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, zirconium, niobium, hafnium and tantalum.

12. The composition for sintering silicon nitride according to claim 11, wherein the transition metal is contained in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the composition.

12. The composition for sintering silicon nitride according to claim 11, further comprising a sintering auxiliary agent, wherein the sintering auxiliary agent comprises at least one oxide selected from the group consisting of aluminum, yttrium and magnesium.

Preparing a molded article by molding a composition comprising a transition metal having an electronegativity of less than 1.23 and less than 1.9 and a primary ionization energy of 600 to 730 kJ / mol; And sintering the molded article.

19. The method of manufacturing a sintered body according to claim 18, wherein the step of producing the molded article comprises ball-milling and pulverizing the mixture, and molding the pulverized material into a film or sheet.

18. The method of producing a sintered body according to claim 17, wherein the step of sintering the molded article comprises holding the molded article under vacuum at a temperature of 1500 to 1800 占 폚 and a pressure of 20 to 40 MPa for 5 to 20 minutes.