JP5057644B2 - Glass ceramic composition and method for producing glass ceramic sintered body - Google Patents

Description

The present invention is an electrical device housing package, a method of manufacturing a multilayer wiring board optimal glass-ceramic compositions applicable wiring board or the like, and the like and glass sintered ceramic ones.

  The rapid development of information communication technology in recent years has led to an increase in the speed of semiconductor devices and the like, and in connection with this, in wiring boards equipped with such devices, in order to reduce signal transmission loss, the wiring layer has been reduced. There is a demand for resistance and a low dielectric constant of the insulating substrate. Therefore, it can be densified by firing at 1000 ° C. or lower, and can be simultaneously fired with a wiring layer mainly composed of a low resistance metal such as gold, silver, copper, etc. A wiring board using a low glass ceramic insulating layer has been proposed.

For example, ceramic powder such as Al ₂ O ₃ , AlN and SiO ₂ is added to glass powder containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , MgO and BaO, and copper, silver, gold, etc. It is described that a glass ceramic sintered body having a small open porosity and high strength and high Young's modulus can be obtained even when fired in a non-oxidizing atmosphere as a wiring layer.
JP 2003-342060 A

  However, the glass-ceramic sintered body described in Patent Document 1 has a high bending strength and a high Young's modulus, so it is excellent in mechanical reliability, but is still used in mobile phones and the like. Therefore, there is a problem that the dielectric loss in the frequency band of 800 MHz or more is large, and thus the transmission loss at high frequency is increased.

Therefore, the present invention can be co-fired with a low resistance metal such as gold, silver, copper, has a lower dielectric constant than alumina, has high strength and high Young's modulus characteristics, and has a lower dielectric constant. If an object and the glass ceramic composition capable of obtaining a glass-ceramic sintered body, to provide a manufacturing how the glass ceramic sintered body having a low dielectric loss.

Glass-ceramic composition of the present invention, at least _SiO 2 20 to 60 _{wt%, B} 2 O 3 _{2~30 wt%, Al} 2 O 3 8 _~25 wt%, MgO 8 to 35 mass%, BaO 10 to 35 weight % As an essential component, the mass ratio of MgO / SiO ₂ is 0.29 to 0.85, the mass ratio of BaO / Al ₂ O ₃ is 0.88 to 2.45, and the mass ratio of MgO / BaO is 0. .3 6 is ～2.07 and the features and the glass powder 35 to 80 wt% which is not substantially free of ZnO and TiO _2, that the ceramic powder containing a 20 to 65 wt% To do.

In the above glass ceramic composition, as further optional components, the glass powder, rare earth oxide _(RE 2 _{O 3)} 1~15 wt% in its total amount of the CaO + SrO 0 to 15 _wt%, a ZrO 2 + SnO2 It is desirable to contain 0 to 5% by mass, and in the glass ceramic composition, it is desirable to contain 0.05% by mass or more of A ₂ O (A: alkali metal element) in the glass powder. Furthermore, it is desirable that the glass transition point (Tg) of this glass powder is 500 ° C to 800 ° C.

  Furthermore, it is desirable that the ceramic powder is at least one selected from the group consisting of alumina, zirconia, forsterite, and enstatite.

The manufacturing method of a glass ceramic sintered body of the present invention, by mixing the above-mentioned glass ceramic composition, molding mixed powder obtained into a predetermined shape, and then that you fired at 1000 ° C. below the temperature It shall be the feature.

According to the present invention, the above-mentioned composition is fired at a low temperature of , for example, 1000 ° C. or lower, so that it has high strength and high Young's modulus characteristics, and has a low dielectric constant and low dielectric loss. You can get a body.

In forming such a glass-ceramic sintered body, the glass-ceramic sintered body after firing is obtained by setting BaO / Al ₂ O ₃ and MgO / BaO to the above ratio in the glass-ceramic composition. In addition to the above-described constituent components, RE ₂ O ₃ (rare earth oxide) can be further added to further increase the Young's modulus and the bending strength, and CaO + SrO or ZrO _2. By containing + SnO ₂ , it becomes easy to control the softening characteristics and crystallization behavior of the glass powder, thereby increasing the crystallinity of the precipitated crystal phase, and the above-mentioned high Young's modulus, high strength In addition, the dielectric constant and dielectric loss can be further reduced.

Furthermore, by containing 0.05% by mass or more of A ₂ O (A: alkali metal element) in the glass powder constituting the glass ceramic composition of the present invention, the glass transition point of the glass ceramic composition is controlled, The sintered body can be densified. That is, in the glass ceramic composition of the present invention, the glass transition point can be controlled to the above-described range by the addition of the above metal oxide, and it becomes easy to control the softening characteristics and crystallization behavior of the glass powder, Thereby, the crystallinity degree of the crystal phase to precipitate can be raised, and the sinterability of a glass ceramic sintered compact can be improved. In this way, it is possible to further reduce the dielectric constant and loss as well as the high Young's modulus and high strength.

Furthermore, according to the present invention, the glass ceramic sintered body obtained after firing can be maintained at low dielectric constant and low dielectric loss by including the ceramic filler as ceramic powder in the glass powder described above. However, the bending strength and Young's modulus can be further increased.

Incidentally, according to the manufacturing method of a glass ceramic sintered body of the present invention, the use of the above glass ceramic composition, possible glass ceramic sintered body obtained after firing to those having high strength, a high Young's modulus.

Glass-ceramic composition of the present invention, at least _SiO 2 20 to 60 _{wt%, B} 2 O 3 _{2~30 wt%, Al} 2 O 3 8 _~25 wt%, MgO 8 to 35 mass%, BaO 10 to 35 weight % was contained as essential components, MgO / SiO ₂ mass ratio of 0.2 from 9 to 0.85, the weight ratio of BaO / _Al 2 _{O 3} is 0.88 to 2.45 and MgO / BaO mass ratio 0.3 6 a ～2.07 and characterized by containing the glass powder 35 to 80 wt% which is not substantially free of ZnO and TiO _2, and the ceramic powder 20 to 65 wt% And

Here, SiO ₂ is a glass network former, celsian contained in glass ceramic sintered body _(BaAl 2 _Si 2 _{O 8)} crystal phase and forsterite (Mg
₂ SiO ₄ ), a constituent component of the enstatite crystal phase (MgSiO ₃ ), and an essential component for precipitating these crystals from the glass during firing.

If the content is less than the above range, it becomes difficult to produce glass powder. Conversely, if the content is more than the above range, the glass transition point rises and the sintered body is sintered at 1000 ° C. or less. The open porosity may be increased. A particularly desirable range of SiO ₂ is 25 to 55% by mass.

Further, B ₂ O ₃ is a glass network former like SiO ₂ and has the effect of facilitating the production of glass powder and at the same time lowering the glass transition point.

When the content is less than the above range, it is difficult to produce glass powder. Conversely, when the content is more than the above range, the chemical resistance of the sintered body is lowered. A particularly desirable range of B ₂ O ₃ is 4 to 25% by mass.

Al ₂ O _{3 is} also a constituent component of the celsian crystal phase, and is an essential component for precipitating the celsian crystal phase from the glass during firing. When the content is less than the above range, the precipitation amount of the celsian crystal phase becomes insufficient and the bending strength is lowered. On the contrary, when the content is larger than the above range, the glass transition point becomes higher than the desired range, and it becomes difficult to achieve densification at a low temperature of 1000 ° C. or lower. A particularly desirable range of Al ₂ O ₃ is 8 to 20% by mass.

  MgO is a constituent component of the forsterite crystal phase, spinel crystal phase, and enstatite crystal phase, and in particular, is an essential component for precipitating the forsterite crystal phase and the enstatite crystal phase from the glass during firing. It is a component that suppresses the precipitation of monoclinic celsian crystal phase.

  When the content is less than the above range, the forsterite crystal phase and the enstatite crystal phase are difficult to precipitate, the dielectric constant increases, and at the same time, the precipitation amount of the monoclinic celsian crystal phase increases. Folding strength is reduced. On the other hand, when the content is larger than the above range, dissolution residue tends to remain during the production of the glass powder, and it becomes difficult to produce the glass powder. A particularly desirable range of MgO is 10 to 30% by mass.

  BaO is also a constituent component of the celsian crystal phase, and is an essential component for precipitating the celsian crystal phase from the glass during firing, and at the same time has an effect of lowering the glass transition point. When the content is less than the above range, the precipitation amount of the celsian crystal phase becomes insufficient and the bending strength is lowered. On the contrary, if the content is more than the above range, the glass transition point is lowered and the binder removal property at the time of firing is deteriorated, and the open porosity may be increased, and at the same time, in the residual glass phase As a result, the dielectric loss may be reduced. A particularly desirable range of BaO is 13 to 30% by mass.

In the present invention, among the above-mentioned essential components, the weight ratio of MgO / SiO ₂ is important to be 0.2 from 9 to 0.8 5. By the mass ratio of MgO / SiO ₂ in the above range, it is possible to properly control the amount of precipitation of celsian crystal phase and forsterite crystal phase, it is possible to improve the crystallinity of the glass ceramic sintered body As a result, the dielectric loss of the glass ceramic sintered body can be reduced. When the mass ratio is out of the above range, the dielectric loss increases, and particularly, the increase in the dielectric loss at a high frequency becomes remarkable. A particularly desirable range of the mass ratio of MgO / SiO ₂ is 0 . 40-0.8.

In the present invention, to obtain a 35 to 80 wt% of the glass powder, the Riga Las ceramic sintered body by the firing a mixed powder containing ceramic powder 25 to 65 wt% at a low temperature of 1000 ° C. or less Can do. This is because the glass powder can be densified at a low temperature of 1000 ° C. or lower as a result of efficient shrinkage of the ceramic powder due to the rearrangement of the ceramic powder due to the softening flow of the glass powder.

  Here, when the content of the glass powder is less than the above range, that is, when the content of the ceramic powder is more than the above range, a dense glass ceramic sintered body is obtained by firing at 1000 ° C. or less. It becomes difficult. Conversely, when the content of the glass powder is larger than the above range, that is, when the content of the ceramic powder is less than the above range, the bending strength of the glass ceramic sintered body, the Young's modulus is reduced, There is a risk of increasing the dielectric loss.

  A particularly desirable range of the glass powder is 40 to 75% by mass, optimally 45 to 70% by mass, and a particularly desirable range of the ceramic powder is particularly 25 to 60% by mass, optimally 30 to 55% by mass. %.

Furthermore, it is important that the glass powder constituting the glass ceramic composition of the present invention does not substantially contain ZnO and TiO ₂ . That is, the term “substantially not contained” means that it is not intentionally contained other than as an impurity. In particular, the content of ZnO and TiO ₂ is 0.1% by mass or less, particularly 0.05% by mass or less. To do.

Here, by setting the mass ratio of BaO / Al ₂ O ₃ within the above range, the amount of precipitation of the celsian crystal phase can be increased, and at the same time, the content of BaO in the residual glass described later can be reduced. It is possible to achieve both high bending strength and low dielectric loss .

  Further, by setting the mass ratio of MgO / BaO within the above range, the precipitation amount of each crystal phase of the celsian crystal phase, the forsterite crystal phase, the spinel crystal phase, and the enstatite crystal phase is within an appropriate range. As a result, it is possible to achieve both high bending strength, low dielectric constant, and low dielectric loss. A particularly desirable range of the mass ratio of MgO / BaO is 0.4 to 1.5.

In yet glass ceramic composition of the present invention, as an optional component of the glass powder, rare earth oxide _(RE 2 _{O 3)} 1 to 15 wt%, 0-15 _wt% of CaO + _SrO, a ZrO ₂ + SnO 2 0 It is desirable to contain -5 mass%.

  Here, the rare earth oxide has an effect of raising the glass transition point and a function as a crystallization accelerator. From the glass of the celsian crystal phase, the forsterite crystal phase, the spinel crystal phase, and the enstatite crystal phase. Precipitation can be promoted and the content of these crystal phases can be increased. At the same time, the inclusion in the residual glass has the effect of improving the Young's modulus of the residual glass phase, and therefore has the effect of improving the Young's modulus and the bending strength of the glass ceramic sintered body.

In particular, the particularly desirable range of the rare earth oxide is 2 to 10% by mass, and among the rare earth oxides, Y ₂ O ₃ and La ₂ O ₃ are particularly effective in improving Young's modulus and are relatively inexpensive. desirable. Here, Y ₂ O _{3 and} La ₂ O ₃ are also one kind of rare earth oxides.

Further, CaO and SrO contained as other optional components have an effect of controlling the softening behavior of the glass, and depending on the content thereof, CaAl ₂ Si ₂ O ₈ crystal phase, SrAl ₂ Si ₂ O ₈ crystal phase, Ca ₂ MgSi ₂ O ₇ crystal phase, CaMgSi ₂ O ₆ , Sr ₂ MgSi ₂ O ₇ crystal phase and other crystal phases containing CaO and SrO are preferable in that they also have an action of precipitating from the glass. . Therefore, by adding the above components, it is possible to control the bending strength, dielectric constant, thermal expansion coefficient, etc. of the glass ceramic sintered body according to the application. And the desirable range of CaO + SrO is 0-10 mass%.

Furthermore, ZrO ₂ and SnO ₂ contained as other optional components have an effect of increasing the glass transition point and a function as a crystallization accelerator, such as celsian crystal phase, forsterite crystal phase, spinel crystal phase. Further, precipitation of enstatite crystal phase from the glass can be promoted, and the content of these crystal phases can be increased. At the same time, it is effective in improving chemical resistance by being contained in the residual glass. A desirable range of ZrO ₂ + SnO ₂ is 0 to 2.5% by mass.

Further, in the glass ceramic composition of the present invention, in that densified sintered body, the glass powder, A 2 _O: the _(A alkali metal element), containing not less than 0.05 wt% Desirably, the amount is preferably 1% by mass or less as the degree of not lowering the insulating property of the sintered body. In particular, 0.1 to 0.5% by mass is more desirable. Note that Na and K are preferably used as the alkali metal element.

In addition, it is desirable that the glass ceramic composition does not substantially contain PbO, CdO, As ₂ O ₃ from the viewpoint of suppressing the influence on the human body and the environment, and high insulation as a glass ceramic sintered body. It is desirable also in terms of obtaining sex. “Substantially not contained” means that the composition is not intentionally contained, and unavoidable impurities may be contained.

  In the glass ceramic composition of the present invention, the glass transition point of the glass powder is from 500 ° C. to 800 ° C. In addition to controlling the softening characteristics and crystallization behavior of the glass powder used, the glass powder is further removed. This is desirable in terms of enhancing the binder property. That is, when the glass transition point is lower than the above range, the firing shrinkage start temperature becomes too low, and there is a possibility that the binder removal property may be impaired even in the air firing, and at the same time, the firing shrinkage occurs rapidly. It becomes difficult to ensure dimensional accuracy. When copper with excellent migration resistance is used for the wiring conductor, firing in a nitrogen atmosphere is performed to suppress copper oxidation. In this case, the temperature required for the binder removal increases. Therefore, the glass transition point is preferably 630 to 800 ° C.

  On the other hand, when the glass transition point is higher than the above range, it becomes difficult to obtain a dense glass ceramic sintered body at a low temperature of 1000 ° C. or lower. A particularly desirable range of the glass transition point is 550 to 750 ° C. in the case of air firing and 650 to 750 ° C. in the case of nitrogen firing.

  In the glass ceramic composition of the present invention, it is desirable that the ceramic powder is at least one selected from the group consisting of alumina, zirconia, forsterite and enstatite.

  These ceramic powders have a high Young's modulus and excellent chemical resistance, and are effective in improving the bending strength, Young's modulus and chemical resistance of the glass ceramic sintered body by mixing, molding and firing with the glass powder. is there. In particular, alumina, forsterite and enstatite powders have a low dielectric loss of the crystal phase itself, and have the effect of reducing the dielectric loss of the glass ceramic sintered body.

  Further, the alumina powder has an effect of partially reacting with the glass powder to increase the precipitation amount of the celsian crystal phase, and the forsterite powder and enstatite powder have the forsterite crystal phase from the glass powder as a core. There is an effect of increasing the precipitation amount of the enstatite crystal phase.

  Alumina is the most desirable as the ceramic powder in that the effect of increasing the bending strength is greatest, and it is desirable that the ceramic powder contains at least alumina, particularly as a main component.

Furthermore, in the present invention, the mixing ratio of the glass powder and the ceramic powder satisfies the quantitative ratio described above, and the bending strength, Young's modulus, dielectric constant, and dielectric loss of the sintered body are not impaired. Insofar as other ceramic powders other than those mentioned above, such as CaAl ₂ Si ₂ O ₈ , SrAl ₂ Si ₂ O ₈ , Ca ₂ MgSi ₂ O ₇ , Sr ₂ MgSi ₂ O ₇ , Ba ₂ MgSi ₂ O ₇ , ZrSiO ₄ , CaMgSi ₂ O ₆ , CaSiO ₃ , CaZrO ₃ , SrSiO ₃ , BaSiO _{3 and the} like can also be mixed.

  Next, the method for producing a glass ceramic sintered body of the present invention will be described in detail below.

First, glass powder and ceramic powder are prepared according to the glass ceramic composition of the present invention. If desired, an organic binder, a plasticizer, and a solvent are added and mixed to adjust the molding slurry.

  Thereafter, a molded body having a predetermined shape is formed by a known existing forming method, for example, a doctor blade method, a calender roll method, a pulling method, a rolling method, press forming, extrusion forming, injection forming, casting forming, or the like.

  The molded body obtained above was subjected to binder removal treatment at 450 to 750 ° C., particularly 450 to 700 ° C. in an air atmosphere and 650 to 750 ° C. in a nitrogen atmosphere, and then 1000 ° C. or less in the air or in a nitrogen atmosphere. The glass-ceramic sintered body of the present invention is obtained by firing at a temperature of preferably 700 to 1000 ° C, more preferably 800 to 950 ° C.

In the glass ceramic sintered body, a specific crystal phase (a) a celsian crystal phase comprising an anisotropic crystal having an aspect ratio of 3 or more, and (b) a forsterite crystal phase, a spinel crystal phase, an enstatite crystal phase, In order to precipitate at least one selected from the group of the above, and to reduce the open porosity of the glass ceramic sintered body, the temperature increase rate after the binder removal treatment is 20 ° C./hour or more, particularly 50 ° C. / Hour or more, optimally 100 ° C./hour or more, and the holding time at the firing temperature is 0.2 to 10 hours, particularly 0.5 to 5 hours, optimally 0.5 to 2 Time is desirable.

By adopting the manufacturing method described above, it can be a glass ceramic composition of the present invention to obtain a desired and to Ruga Las ceramic sintered body.

  Here, in the present invention, it is desirable that the crystal phases (a) and (b) are precipitated from the glass powder during firing at a temperature of 1000 ° C. or less, whereby the crystallinity of the glass is increased. Since the content of the crystal phase in the sintered body can be improved without increasing the content of the residual glass phase (d) and without inhibiting the sinterability, the open porosity is lowered. At the same time, Young's modulus and bending strength can be increased.

It will be described based on FIG. 1 with respect to the resulting Ruga Las ceramic sintered body by the above production method. That is , this glass ceramic sintered body is selected from the group consisting of (a) a celsian crystal phase comprising an anisotropic crystal having an aspect ratio of 3 or more, and (b) a forsterite crystal phase, a spinel crystal phase, and an enstatite crystal phase. At least one kind, (c) at least one kind of crystal phase among alumina crystal phase and zirconia crystal phase, and (d) a residual glass phase having a BaO content of 8 % by mass or less, and open porosity of Ru der 0.3% or less.

The crystal phase (a) is a celsian crystal phase and is represented by BaAl ₂ Si ₂ O ₈ as a stoichiometric composition. In the present invention, it is a glass ceramic that the celsian crystal phase contains an anisotropic crystal (shown as 11a in FIG. 1) having an aspect ratio of 3 or more, preferably 4 or more, and more preferably 5 or more. As a result of being able to improve the fracture energy of the sintered body, it is desirable in that the bending strength can be improved. The aspect ratio of the anisotropic crystal is large in the aspect ratio (major axis / minor axis ratio) of the celsian (BaAl ₂ Si ₂ O ₈ ) crystal phase observed by the cross-sectional SEM and EPMA analysis of the sintered body. It means the average value when 10 are selected, and the needle-like crystal 11a is particularly desirable to have a major axis of 1 to 10 μm and a minor axis of 0.1 to 2 μm. It is desirable that the acicular crystals 11a are randomly dispersed in that the bending strength is improved by improving the breaking energy.

  Further, the celsian crystal phase (a) may include granular crystals (indicated by 11b in FIG. 1) in addition to the anisotropic crystals 11a. In addition, the anisotropic crystal here refers to that the shape of a crystal grain has anisotropy, and specifically refers to having a needle-like or plate-like shape.

And it becomes contain the celsian crystal phase (a) is hexagonal (hex), or hexagonal (hex) and monoclinic (mon) both crystalline phase, X-rays obtained by the X-ray diffraction measurement The diffraction pattern is represented by the right formula: I (hex) / I (mon) (where I (hex) is the hexagonal main peak intensity and I (mon) is the monoclinic main peak intensity). The main peak intensity ratio of 3 or more, preferably 5 or more, and most preferably 7 or more is desirable from the viewpoint of improving the bending strength of the glass ceramic sintered body.

  That is, the hexagonal crystal forms the anisotropic crystal 11a, and the monoclinic crystal forms the granular crystal 11b. Therefore, when the main peak intensity ratio is within the above range, a large amount of anisotropic crystal 11a is precipitated, and as a result, the bending strength of the sintered body can be increased.

  The hexagonal crystal indicates the crystal phase of JCPDS card 28-0124, the monoclinic crystal indicates the crystal phase of 38-1450, and each main peak is the X-ray diffraction diagram of these crystal phases. It means the peak with the highest intensity. The hexagonal main peak corresponds to a peak with a d value of 3.900, and the monoclinic main peak corresponds to a peak with a d value of 3.355. Therefore, the peak intensity ratio is calculated as I (d = 3.900) / I (d = 3.355).

Next, the crystal phase (b) is at least one selected from the group of forsterite crystal phase, spinel crystal phase, and enstatite crystal phase (reference numeral 12 in FIG. 1), and the stoichiometric composition is Mg, respectively. _It has a chemical composition represented by ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ . Since these crystal phases have a high Young's modulus as a single crystal, it is possible to increase the Young's modulus of the glass ceramic sintered body by precipitating these crystal phases.

  The crystal phase (b) preferably has an average particle size of 1 μm or less. By dispersing such fine crystals in the sintered body, the structure of the sintered body can be refined and densified, so that the bending strength can be increased.

  Furthermore, the crystal phase (c) is a ceramic crystal phase resulting from the ceramic powder, and in particular, is at least one crystal phase of alumina and zirconia (reference numeral 13 in FIG. 1). As described above, the crystal phase (c) has an effect of improving the bending strength and chemical resistance of the glass ceramic sintered body.

Furthermore, the bending strength of the glass ceramic sintered body, the Young's modulus, dielectric constant, as long as the dielectric loss is not impaired, other ceramic crystal phases other than the above, for example, _{CaAl 2 Si 2 O 8, SrAl} 2 Si 2 O ₈ , Ca ₂ MgSi ₂ O ₇ , Sr ₂ MgSi ₂ O ₇ , Ba ₂ MgSi ₂ O ₇ , ZrSiO ₄ , CaMgSi ₂ O ₆ , CaSiO ₃ , CaZrO ₃ , SrSiO ₃ , BaSiO ₃ , YAlO ₃ , Y ₄ Al ₂ O ₉ , BaY ₂ O ₄ , Y ₄ Zr ₃ O ₁₂ , Y ₆ ZrO ₁₁ or the like may be contained.

Further, in the glass ceramic sintered body of that, A 2 _{O (A:} alkali metal element) may be contained 0.04 wt%, in that it does not impair the insulating properties of the sintered body, 0 .8% by mass or less, and more preferably 0.08 to 0.4% by mass.

As described above, it is desirable that the mixed powder, which is a glass ceramic composition, does not substantially contain PbO, CdO, As ₂ O ₃ in order to reduce environmental burden and obtain high insulation. Similarly to this, it is desirable that this sintered body does not substantially contain the metal oxide.

  Further, in FIG. 1, the residual glass phase (d) is obtained by forming and firing the mixed powder of the glass powder and the ceramic powder, thereby changing the crystal phase (a) and (b) from the glass powder during firing. This is a phase that remains as an amorphous glass phase in the sintered body after precipitation (reference numeral RG in FIG. 1).

Further, the content of BaO in the residual glass phase (d) is not more than 8 wt% may in order to achieve a low dielectric loss. That is, by reducing the amount of BaO contained in the residual glass phase (d), it is possible to reduce dielectric loss particularly at high frequencies.

  Therefore, when the content is larger than the above range, the dielectric loss of the glass ceramic sintered body becomes large and deviates from a desirable range. A particularly desirable range of the BaO content is 8% by mass or less, and optimally 4% by mass or less.

Further, the glass-ceramic sintered body this, the open porosity of Ru der 0.3% or less. That is, by using a dense glass ceramic sintered body, the bending strength and Young's modulus can be increased, and at the same time, a fine thin-film wiring layer to be described later can be formed with a uniform thickness with high accuracy.

  When the open porosity is larger than the above range, the bending strength and Young's modulus may be lower than desired ranges, and the thin film wiring layer can be formed with a uniform thickness and high accuracy. It becomes difficult. A particularly desirable range of open porosity is 0.25% or less, and optimally 0.2% or less.

And in the above-mentioned glass-ceramic sintered compact, by setting it as the structure explained in full detail above, the relative dielectric constant in 800 MHz-10 GHz is 9 or less, Especially 8.5 or less, Optimally 8.0 or less, The dielectric loss in the same frequency band can be 0.002 or less, particularly 0.0018 or less, and optimally 0.0015 or less. When the measurement frequency is 1 MHz, the dielectric loss value is 0. 0.001 or less, particularly 0.0008 or less, and optimally 0.0005 or less.

  Furthermore, the Young's modulus can be 100 GPa or more, particularly 120 GPa or more, optimally 140 GPa or more, and the bending strength can be 280 GPa or more, particularly 300 MPa or more, optimally 320 MPa or more.

Next, glass ceramic sintered body described above, is very useful as an insulating substrate for various wiring board. FIG. 2 shows a schematic cross-sectional view of a typical electrical element storage package as an example of such a wiring board.

  In FIG. 2, the package A includes an insulating substrate 1 composed of a plurality of insulating layers 1a to 1d, and a wiring made of a low resistance metal such as silver, copper, or gold on the surface and inside of the insulating substrate 1. Layer 2 is formed. A via-hole conductor 3 for electrically connecting the wiring layer 2 is formed so as to penetrate the insulating layers 1a to 1d. The via-hole conductor 3 contains a low resistance metal such as gold, silver, or copper. Further, a plurality of connection electrodes 4 are arranged on the lower surface of the package A, and the connection electrodes 4 are connected to connection electrodes 8 of an external circuit board B such as a printed circuit board. The electric element includes a semiconductor element such as Si or GaAs or an element such as a SAW device.

  At the center of the upper surface of the insulating substrate 1, a device 5 such as an electric element is bonded and fixed via an adhesive (not shown) such as glass or an underfill agent, and the surface of the device 5 is sealed with a potting agent or the like. Sealed with a stop resin 7. The device 5 is electrically connected to the wiring layer 2 through the wire bonding 6 or the like. Therefore, the device 5 and the plurality of connection electrodes 4 formed on the lower surface of the insulating substrate 1 are connected to the wiring layer 2 and via-hole conductors. 3 is electrically connected.

Thus, by forming the insulating substrate 1 using the glass ceramic sintered body described above, the bending strength and Young's modulus of the insulating substrate 1 can be increased, and at the same time, the dielectric constant and the dielectric loss are reduced. As a result, the mechanical reliability and high-frequency characteristics, particularly the transmission characteristics, of the package A can be improved.

  Moreover, since the insulating substrate 1 can be produced by low-temperature firing at 1000 ° C. or lower, a low-resistance conductor that has at least one low-resistance metal selected from the group of gold, silver, and copper as a main component is used. The wiring layer 2 can be formed by simultaneous firing. Therefore, the resistance of the wiring layer 2 can be reduced and the signal delay can be reduced.

  In FIG. 2, the device 5 is connected to the wiring layer 2 via the wire bonding 6, but the so-called flip chip mounting in which the device 5 is directly connected to the wiring layer 2 on the surface of the insulating substrate 1 by soldering or the like. You can also Further, without using the sealing resin 7, a cavity is formed on the surface of the insulating substrate 1 to store the device 5, and a sealing metal fitting (not shown) or the like is used to form a cavity in which the device 5 is stored by the lid. It can also be sealed. Further, if necessary, various heat sinks can be deposited on the surface of the insulating substrate via a brazing material.

Since the insulating substrate 1 made of the glass ceramic sintered body has a high Young's modulus of 100 GPa or more, the insulating substrate 1 can be deformed or warped even if a sealing metal fitting, a heat sink, or the like is formed on the insulating substrate 1. Furthermore, since the bending strength is as high as 280 MPa or more, it is possible to suppress the breakdown of the insulating substrate 1 when a sealing metal fitting, a heat sink, or the like is deposited, or due to a drop test or the like. It is possible to obtain excellent mechanical reliability.

  A wiring board such as the above-described package can be manufactured in the same manner as the above-described glass ceramic sintered body is manufactured. That is, a molding slurry is prepared using a mixed powder obtained by mixing the glass powder and ceramic powder described above in a certain quantitative ratio, and a ceramic green sheet (insulating) having a thickness of, for example, 50 to 500 μm is prepared using the molding slurry. Sheets for layers 1a-1d) are formed.

  A through hole is formed at a predetermined position of the green sheet, and a conductive paste containing a low resistance metal such as copper, silver, or gold is filled in the through hole. Further, on the surface of the green sheet corresponding to the insulating layer on which the wiring layer 2 is formed, the wiring layer 2 using the above-mentioned conductor paste and a known printing method such as a screen printing method or a gravure printing method. The wiring pattern is printed and applied so that the thickness of the film becomes 5 to 30 μm.

  Then, the plurality of green sheets prepared as described above were aligned and laminated and pressure-bonded, and then subjected to binder removal treatment at a temperature of 450 to 750 ° C. in the atmosphere or in a nitrogen atmosphere containing water vapor. Then, the insulating substrate 1 provided with the wiring layer 2 is produced by firing in the air at 1000 ° C. or lower or in a nitrogen atmosphere.

  Note that the binder removal atmosphere and firing atmosphere are appropriately determined according to the type of low-resistance metal used. For example, when copper is used as the wiring conductor, it is oxidized by firing in the air. Binder removal or firing is performed.

  A device 5 such as a semiconductor element is mounted on the surface of the insulating substrate 1 formed as described above, and is connected to the wiring layer 2 so that signals can be transmitted. As described above, the device 5 can be directly mounted on the wiring layer 2 to connect them, or the device 5 and the wiring layer 2 on the surface of the insulating substrate 1 are connected using the wire bonding 6. You can also Moreover, it is also possible to connect both by flip chip mounting.

  Further, the sealing resin 7 is applied to the surface of the insulating substrate 1 on which the device 5 is mounted and cured, or from the same type of insulating material as the insulating substrate 1, other insulating materials, or a metal with good heat dissipation. The device 5 can be hermetically sealed by bonding the lid body to be formed with an adhesive such as glass, resin, or brazing material, whereby the package A can be manufactured. Further, if necessary, various heat sinks can be deposited on the surface of the insulating substrate via a brazing material.

Thus, since the above-mentioned glass ceramic sintered body can be manufactured by firing at a low temperature of 1000 ° C. or lower, by using such a glass ceramic sintered body as an insulating substrate material, gold, silver, copper, etc. By simultaneous firing with the low-resistance conductor, the wiring layer made of these low-resistance conductors and the insulating substrate can be integrally manufactured, and the production efficiency of various wiring boards can be increased.

Moreover, since the above-mentioned glass ceramic sintered body has a high bending strength and a high Young's modulus and exhibits excellent mechanical reliability, the thickness of the insulating substrate 1 as described above is 0.5 mm or less, particularly It can also be 0.4 mm or less, and further 0.2 mm or less, and is useful for manufacturing a thin and highly reliable wiring board.

  Furthermore, since the dielectric constant and dielectric loss at high frequencies are particularly low, the loss of high-frequency signals is small and the high-frequency characteristics are excellent. It is.

As detailed above, according to the present invention, at least SiO ₂ : 20 to 60% by mass, B ₂ O ₃ : 2 to 30% by mass, Al ₂ O ₃ : 5 to 25% by mass, MgO: 8 to 35% by mass, Glass powder containing BaO: 10 to 35% by mass as an essential component, MgO / SiO ₂ mass ratio of 0.20 to 0.85, and substantially free of ZnO and TiO ₂ : 35 Since glass ceramic composition characterized by containing -80 mass% and ceramic powder: 20-65 mass% can be baked at low temperature of 1000 degrees C or less, it is low resistance, such as gold | metal | money, silver, copper A sintered body that can be co-fired with a metal, achieves a small open porosity, and has high bending strength, high Young's modulus, low dielectric constant, and low dielectric loss can be obtained.

Further, by using the above glass ceramic sintered body as an insulating substrate in a wiring substrate, it is possible to obtain a highly reliable wiring substrate that can withstand a drop test and the like, and a dielectric constant particularly at a high frequency. Since the dielectric loss is low, an insulating substrate exhibiting good high frequency characteristics can be obtained, so that it is suitably used for any wiring substrate.

Hereinafter, the thin film wiring board, based on the accompanying drawings which illustrate an embodiment will be described in detail. Figure 3 is a partially enlarged cross-sectional view for explaining the structure of the thin-film wiring layer Y formed on the surface of the semiconductor device package for housing, which is an example of the application of the wiring substrate.

  The thin film wiring substrate C includes a wiring substrate X and a thin film wiring layer Y having a laminated structure of a thin film metal layer 14 and a thin film insulating layer 15 formed on the surface of the wiring substrate X. The thin film wiring layer Y is a surface of the wiring substrate X. In addition, the thin film metal layer-thin film insulation layer --- thin film insulation layer-thin film metal layer are laminated in this order, and according to FIG. The layers 14a, 14b, and 14c are formed, and the thin film metal layers 14a-14b and 14b-14c are electrically connected at a position where a part of the thin film insulating layer 15 is removed. The electrode terminal 16 of the semiconductor element 5 as the device 5 is mounted and connected to the thin-film metal layer 14a on the outermost surface of the thin-film wiring layer Y.

The insulating substrate 17 constituting the front Symbol wiring board X, by forming a glass ceramic sintered body of low above the open porosity described above, a result of the surface can be smooth in the insulating substrate 17, on its surface A fine thin-film metal containing a metal selected from at least one selected from the group consisting of copper, silver, gold, and aluminum, for example, a wiring width of 20 μm or less, particularly 15 μm or less, and an interval between wirings of 20 μm or less, particularly 10 μm or less. Since the layer 14 can be accurately formed with a uniform thickness, a thin film wiring substrate C on which the thin film wiring layer Y is formed, which has a high bending strength, a high Young's modulus, a low dielectric constant, and a low dielectric loss, is produced. Can do.

  That is, when the open porosity of the insulating substrate 17 exceeds the above range, the positional accuracy of the thin film wiring layer Y is lowered, fine wiring cannot be formed, and variations in the wiring layer thickness and wiring width increase. The impedance characteristics of the signal transmitted through the wiring layer deteriorate, and in the worst case, it may cause an open or short circuit failure.

Furthermore, it is possible to reduce not only the open pores but also the closed pores by using the above-mentioned glass ceramic sintered body for the insulating substrate 17, and therefore the surface roughness of the polished surface can be reduced especially by performing a polishing process. (Ra) is 0.1 μm or less, particularly 0.07 μm or less, optimally 0.05 μm or less, and the area ratio of pores existing on the polished surface is 10% or less, particularly 8% or less, optimally 5% or less. can do.

  On the other hand, in order to omit the polishing process of the surface of the insulating substrate 17 to improve productivity and simplify the process, the surface roughness (Ra) of the surface of the glass ceramic is 1.0 μm or less, particularly 0.7 μm or less. It is desirable to be.

  Furthermore, the thin film metal layer 14 in the thin film wiring layer Y contains at least one low resistance metal selected from the group of copper, silver, gold, and aluminum, and includes Ti, W, Mo, Cr, Ni, Ta as other components. It is desirable that at least one metal layer selected from the Sn group has a structure in which a plurality of layers are stacked. Of the thin film metal layer 14, the thickness of the thin film metal layer 14c directly formed on the surface of the wiring board X is 0.1 to 3 μm, particularly 0.3 to 1.5 μm in order to increase the adhesive strength. It is desirable to form a metal layer containing W or Mo, whereby the adhesion strength of the thin film metal layer 14 to the wiring board can be increased.

  Further, the W, Mo-containing layer preferably contains W and / or Mo in an amount of 50% by weight or more, particularly 70% by weight or more, and particularly preferably an alloy layer with Ti.

  The thin metal layer 14c may be a laminated body of a copper layer and a W, Mo-containing layer. However, in order to increase the adhesive force between the wiring substrate X and the insulating substrate 17, a thickness of 0.05 on the surface of the wiring substrate X is provided. A W, Mo-containing layer is laminated through a Ti layer having a thickness of ˜0.5 μm, and a Cu-containing layer having a thickness of 1 to 10 μm is formed as the main conductor layer, so that the thickness is 1.5 to 15 μm as a whole. desirable. Further, a Cr layer may be formed on the surface in contact with the insulating film in order to improve the adhesion with the thin film insulating layer 15.

  Furthermore, the thin film metal layers 14a and 14b include at least one metal layer selected from the group of Cu, Ag and Au of at least 1 to 10 μm, and further from the group of Ti, W, Mo, Cr, Ni and Ta. It is desirable to include at least one selected metal layer, and in particular, by interposing a Cr layer between the Cu layer and the thin film insulating layer 15, the adhesive force with the insulating film can be enhanced. Similarly, the thickness of the thin metal layers 14a and 14b is suitably 1.5 to 15 μm.

  In addition, as the thin film insulating layer 15 in the thin film wiring layer Y, a polyimide-based or epoxy-based organic polymer material can be used. In particular, the polyimide-based organic polymer is low in terms of low dielectric constant and low dielectric loss. It is desirable to use materials. The thickness of the thin film insulating layer 15 is preferably 5 to 100 μm, particularly 10 to 50 μm.

The main surface of the wiring board X above SL, a thin film wiring layer Y. The thin film wiring layer Y is formed by the following process.

(1) A thin film composed of a plurality of metal layers on the entire upper surface of the wiring board X using a different deposition source by a thin film method such as sputtering, ion plating, vacuum deposition, etc. The metal layer 14 is formed with a thickness of 1.5 to 15 μm. Next, a photosensitive photoresist is applied on the entire surface of the thin film. Then, an etching mask is prepared by a well-known photolithography technique, and an unnecessary portion of the thin film metal layer is formed on the thin film metal layer 14 by reactive ion dry etching using an acidic etchant or a reactive gas (CCl ₄ , BCl ₃ ). Is removed to obtain a thin film metal layer 14c having a predetermined pattern. Thereafter, the etching mask is removed by peeling.

(2) Next, the thin film insulating layer 15 made of an organic polymer insulating material such as polyimide is formed on the thin film metal layer 14c. For example, a polymer solution of an organic polymer material is uniformly applied to the upper surface of the wiring board X by a spin coating method or the like, and heated to a temperature at which the organic polymer material is cured.

(3) Next, connection through holes for connecting the upper and lower thin film metal layers 14 are formed by using a conventionally well-known photolithography technique.

  By repeatedly performing the above steps (1), (2) and (3), a predetermined plurality of thin-film metal layers 14 and thin-film insulation layers 15 can be formed, whereby the thin-film wiring board C of the present invention. Can be produced.

  First, glass powder having the composition and glass transition point shown in Tables 1 to 3 (average particle size is 2 μm) and four ceramic powders shown in Tables 4 to 6 (average particle size is alumina, forsterite, enstatite) 2 μm and zirconia 0.8 μm).

  And using the said glass powder and ceramic powder, it mixed according to the composition of Tables 4-6, an organic binder, a plasticizer, and toluene were added to this mixture, and after preparing a slurry, doctor blade method was used using this slurry. Thus, a sheet-like molded body having a thickness of 300 μm was produced. Further, a plurality of the sheet-like molded bodies were laminated so as to have a desired thickness, and thermocompression bonding was performed by applying a pressure of 10 MPa at a temperature of 60 ° C.

  The obtained laminate was treated to remove the binder at 500 ° C. in the air, then heated at 200 ° C./hour, and fired in the air under the conditions shown in Tables 4 to 6 to obtain a glass ceramic sintered body. .

  Next, the open porosity of the obtained glass ceramic sintered body was measured by Archimedes method. Further, this glass ceramic sintered body was processed into 3 mm × 4 mm × 50 mm, and Young's modulus was measured by an ultrasonic pulse method. Moreover, the three-point bending strength based on JIS R-1601 was measured using the same sample using the autograph.

  Further, the glass ceramic sintered body was processed into a size of 50 mm × 50 mm × 1 mm, and the dielectric constant and dielectric loss at 2 GHz were measured by a dielectric-filled cavity resonator method. Furthermore, an In—Ga paste was applied to the front and back surfaces of the ceramic sintered body processed to 20 mmφ × 1 mmt, and dielectric loss at 1 MHz was measured using an LCR meter. At this time, the dielectric loss of the sapphire substrate was set to zero.

  Furthermore, the glass ceramic sintered body was pulverized, the crystal phase was identified from the X-ray diffraction measurement, and the magnitude of the main peak intensity was compared.

For the BaAl ₂ Si ₂ O ₈ crystal phase, the hexagonal main peak is d = 3.900, the monoclinic main peak is d = 3.355, and the peak intensity ratio I (d = 3.900). ) / I (d = 3.355).

Furthermore, the ceramic sintered body was mirror-polished, and the aspect ratio of the BaAl ₂ Si ₂ O ₈ crystal phase (needle crystals) was calculated from a scanning electron microscope (SEM) photograph. These results are shown in Tables 4-6.

  Further, the BaO content of the residual glass phase was measured using an X-ray microanalyzer (TEM-XMA) attached to the transmission electron microscope. The above measurement results are shown in Tables 4-6.

  On the other hand, it evaluated similarly using the glass N and P shown in Table 1 as a comparative example. Furthermore, the same evaluation was performed using quartz glass as the ceramic powder instead of the crystal phase (c). The results are shown in Tables 4-6.

The precipitated crystal phases shown in the table are H: celsian (hexagonal), M: celsian (monoclinic), Fo: forsterite, SP: spinel, En: enstatite, A: alumina, Z: zirconia, Abbreviated as DI: diopsite (CaMgSi ₂ O ₆ ), An: anorthite (CaAl ₂ Si ₂ O ₈ ), YZ: Y ₆ ZrO ₁₁ .

As is apparent from the results of Tables 1 to 6, Sample No. which is a glass ceramic sintered body obtained by firing at 1000 ° C. or lower using the glass ceramic composition of the present invention. About 2-20 , 22-29 , 34-52 , 54-63 , 64-85 , the crystal phase corresponding to the crystal phase (a)-(c) mentioned above is contained, and in residual glass (d) The BaO content was 8 % by mass or less, and the open porosity was 0.3% or less.

In these samples, the dielectric loss at 2 GHz was a low value of 0.002 or less .

Further, for these samples, hexagonal in X-ray diffraction measurement (hex.) And monoclinic (mon.) And the main peak intensity ratio I of (hex.) / I (mon .) There are at least 3 comprises celsian crystal phase (a) is at least an aspect ratio of 5 or more needles, a Young's modulus of 1 22 GPa or more, flexural strength than 280 MPa, dielectric constant at 2GHz 8. It was 5 or less.

  On the other hand, the amount of the glass powder is more than 80% by weight of the sample No. In No. 1, the filler was insufficient and the bending strength was less than 280 MPa. In No. 30, a dense sintered body could not be obtained at a temperature of 1000 ° C. or lower.

  Sample No. 21 and 53 do not contain any of the crystal phase (c), so that the Young's modulus is lower than 100 GPa, the bending strength is lower than 280 MPa, and the dielectric loss at 2 GHz is higher than 0.002. became.

  Furthermore, sample No. using glass N and P which are outside the composition range of this invention as glass powder of predetermined amount. In both 31 and 33, the dielectric loss at 2 GHz was larger than 0.002.

  Sample No. 1 of Example 1 An acrylic binder, a plasticizer, and toluene were added to and mixed with the raw material powder of 16 samples, and a sheet-like molded body having a thickness of 250 μm was produced by a doctor blade method. Next, a via hole is formed at a predetermined position of the sheet-shaped molded body, and after filling a conductor paste mainly composed of copper, a wiring pattern is formed on the surface of the sheet-shaped molded body using the conductor paste by a screen printing method. Formed.

And 4 sheets were laminated | stacked and thermocompression bonded, aligning the sheet-like molded object in which the said wiring pattern was formed. During this laminate _{N 2} / _H 2 O atmosphere, after binder removal treatment at 700 ° C., the temperature was raised at 200 ° C. / _time, in N ₂ / _H 2 O atmosphere, copper and calcined 1 hour at 900 ° C. 100 wiring boards having a cavity structure with an outer dimension of 5 mm □ × 0.8 mmt were prepared.

  About the obtained wiring board, after mounting a semiconductor element, it was sealed with a metal fitting made of Fe-Ni-Co alloy, and showed no warpage, deformation, cracking of the insulating board, etc., and good airtightness It was confirmed that it has a stopping property. Furthermore, when the continuity and high frequency characteristics of the wiring layer were confirmed, there was no disconnection or the like, and good continuity and transmission characteristics were exhibited with low resistance.

  Furthermore, the above wiring board is mounted on a printed board of 100 mm × 40 mm × 1 mmt, screwed to a plastic case, and subjected to a drop test 6 times × 3 times from a height of 2 m. It was confirmed that there was no destruction of the part.

  A Ti layer having a thickness of 0.2 μm was formed on the insulating substrate surface of the flat wiring board without a cavity by a vacuum evaporation method in the same manner as in Example 2, and then various TiW, TiMo, After forming various metal layers of Ni, Cr, and Ta with a thickness of 10 μm, a copper layer was formed with a thickness of 3 μm. The contents of W and Mo in the alloy layer of TiW and TiMo are 90% by weight.

  Thereafter, a photosensitive photoresist is applied to the entire surface of the thin film metal layer, an etching mask is formed by photolithography technique, and an unnecessary portion of the thin film is removed from the thin film layer with an acidic etching solution. A 1 mm evaluation pad was formed.

  Then, a copper pin is soldered to the pad, and the circuit board is held in a thermostat controlled at -40 ° C. and 125 ° C. for 15 minutes / 15 minutes. One cycle is 100 cycles. After the thermal cycle, this pin was pulled up vertically and the strength when the solder or thin film metal layer was separated was evaluated as the adhesion strength of the thin film metal layer. The adhesion strength was 22.5 MPa or more, and good adhesion Showed sex.

It is a figure which shows the structure of a glass ceramic sintered compact. It is a sectional side view which shows an example of the wiring board (semiconductor element storage package) which uses a glass ceramic sintered compact as an insulating substrate. It is a side sectional view showing an example of the thin film wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Wiring layer 3 Via-hole conductor 4 Connection electrode 5 Device, semiconductor element 11 Crystal phase (a)
12 Crystalline phase (b)
13 Crystalline phase (c)
RD Residual glass (d)
14 Thin Metal Layer 15 Thin Film Insulating Layer 16 Electrode Terminal 17 Insulating Substrate A Semiconductor Device Storage Package (Wiring Board)
B External circuit board C Package for housing semiconductor elements (thin film wiring board)
X Wiring board Y Thin film wiring layer

Claims (6)

At least SiO ₂ 20-60% by mass,
B ₂ O ₃ 2-30% by mass,
Al ₂ O ₃ 8 ~25 wt%,
MgO 8-35% by mass,
BaO 10-35% by mass
As an essential component,
The mass ratio of MgO / SiO ₂ is 0.29 to 0.85,
BaO / _Al mass ratio 2 _{O 3} is 0.88 to 2.45 and MgO / BaO weight ratio is 0.3 from 6 to 2.07,
And substantially and 35 to 80 wt% of a glass powder containing no ZnO and TiO _2, glass ceramic composition characterized by containing a 20 to 65% by weight of ceramic powder. Furthermore, as an optional component, the glass powder
1 to 15% by mass of the total amount of rare earth oxide (RE ₂ O ₃ ),
0-15 mass% of CaO + SrO,
0-5% by mass of ZrO ₂ + SnO ₂ ,
The glass ceramic composition according to claim 1, comprising: The glass ceramic composition according to claim 1, wherein the glass powder contains 0.05% by mass or more of A ₂ O (A: alkali metal element).   4. The glass ceramic composition according to claim 1, wherein the glass powder has a glass transition point (Tg) of 500 ° C. to 800 ° C. 5. The glass ceramic composition according to any one of claims 1 to 4, wherein the ceramic powder is at least one selected from the group consisting of alumina, zirconia, forsterite, and enstatite. A glass-ceramic sintering comprising mixing the glass-ceramic composition according to any one of claims 1 to 5, molding the obtained mixed powder into a predetermined shape, and then firing at a temperature of 1000 ° C or lower. Body manufacturing method.

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