JP5566764B2 - Low temperature fired high strength low thermal expansion ceramic - Google Patents

Description

  The present invention relates to a low-temperature fired high-strength low-thermal-expansion ceramic and a method for producing the same. More specifically, the present invention is highly reliable as a multi-layer substrate material, can be co-fired with a low resistance metal such as Ag, Au, Cu, etc., can be fired at low temperature, can realize low thermal expansion, and can be anodic bonded. The present invention relates to a method for producing such a high-strength low thermal expansion ceramic and a high-strength low thermal expansion ceramic obtained by the method.

  In recent years, with the advent of advanced information technology, semiconductor devices are required to have higher integration, higher integration, and higher mounting density. The use of low-resistivity wiring materials (Ag, Au, Cu, etc.) is required for higher integration and higher packaging density. However, since these metals have a low melting point, the substrate is printed after the wiring pattern is printed. In a multilayer wiring board or the like to be fired, it is necessary to use a substrate material system (LTCC board) that can be fired at a low temperature. Therefore, there is a need for a material that can be fired at a low temperature in place of an alumina substrate that has been widely used as a substrate material for electronic equipment.

Recently, glass ceramic materials composed of glass and inorganic fillers have been studied. For example, JP 2000-188017 A (Patent Document 1) contains a glass phase capable of precipitating a diopside (CaMgSi ₂ O ₆ ) type crystal phase and Mg and / or Zn and Ti as fillers. A porcelain composition containing an oxide that can be fired at 1000 ° C. or lower is disclosed. Since this type of glass ceramic material can be fired at a temperature of 800 to 1000 ° C., it has a feature that it can be fired simultaneously with Ag, Au, Cu or the like having a low conductor resistance. In addition to the stability of characteristics resulting from dielectric constant and moisture resistance, it is possible to form built-in passive components using dielectrics and wiring inside ceramics, so LTCC substrates are used as high frequency applications as communication devices and measuring devices. Many are used. When actually applied to a product, the substrate is required to have not only functionality but also mountability and reliability at the time of secondary mounting. At this time, it is required that the thermal expansion coefficient is close to that of the substrate on which the thermal expansion coefficient is mounted. For example, when considering wafer level mounting with silicon in MEMS (Micro Electro Mechanical Systems) applications, etc., a material having a low thermal expansion coefficient that matches that of silicon is required.

  Conventionally, cordierite ceramics and lithium aluminosilicate ceramics are known as low thermal expansion ceramics. Cordierite ceramics are manufactured by adding a sintering aid to a raw material powder, forming it into a predetermined shape, and firing it at a temperature of 1000 to 1400 ° C. (JP-A-2-229760: Patent Document 2). As for lithium aluminosilicate ceramics, β-spodumene is produced by forming a raw material into a predetermined shape and firing it at a temperature of 1100 to 1400 ° C. (Japanese Patent Publication No. 53-9605: Patent Document 3).

  Thus, there is a demand for low thermal expansion ceramics that can be fired at low temperature and have low thermal expansion, but those having low thermal expansion have a problem of high firing temperature.

In order to solve this problem, the present inventors have previously described the formula: (1-x) (αLi ₂ O—βMgO—γAl ₂ O ₃ —δSiO ₂ ) · xBi ₂ O ₃ (wherein x is 0.01 to 0.1 by mass ratio, α, β, γ and δ are molar ratios of α: β: γ: δ = 2 to 5: 1 to 2: 1 to 2: 7 to 17) A high-strength, low-thermal-expansion porcelain containing a composite oxide having a low-temperature was proposed (Japanese Patent Laid-Open No. 2009-263189: Patent Document 4). This porcelain is (A) a molar ratio α: β: Li ₂ O or a lithium compound that becomes Li ₂ O when fired and MgO or a magnesium compound that becomes MgO when fired and Al ₂ O ₃ and SiO _2. Raw material composition containing 90 to 99% by mass of raw material powder mixture in which γ: δ is in the range of 2 to 5: 1 to 2: 1 to 2: 7 to 17 and (B) 1 to 10% by mass of Bi ₂ O ₃ powder. The material powder is calcined at 750 ° C. to 850 ° C. and then pulverized to obtain a powder having an average particle size (D ₅₀ ) of about 1 μm, which is formed into a predetermined shape and then fired at 850 ° C. to 900 ° C. By using 1 to 10% by mass of Bi oxide as a liquid phase forming component, a β-spodumene crystal phase and / or a Li ₂ O—Al ₂ O ₃ —SiO ₂ crystal phase, a Li ₂ O—SiO ₂ system A high-strength, low-thermal-expansion ceramic having a linear phase thermal expansion coefficient of 0 to 5 × 10 ⁻⁶ / ° C. at room temperature to 400 ° C. and a flexural strength of 150 MPa or more, having a crystal phase and a MgO—SiO ₂ crystal phase as a main phase It can be fired at a low temperature of 850 to 900 ° C., and a wiring made of Cu, Au, Ag or the like can be formed by simultaneous firing, and is therefore suitable as a low thermal expansion LTCC (low temperature fired multilayer substrate). It is.

  The inventors of the present invention have studied the composition of Example 5 in which a high bending strength of 305 MPa was obtained in the example of Patent Document 4 with the aim of further improving the bending strength. Was found to have a bending strength of 250 to 300 MPa.

In this examination, a method different from the method of Patent Document 4 was adopted as a method of manufacturing a high-strength low thermal expansion ceramic. That is, in Patent Document 4, a raw material composition powder composed of a lithium compound, a magnesium compound, Al ₂ O _3, SiO ₂ and Bi ₂ O ₃ is calcined and then pulverized to obtain a powder having an average particle size of about 1 μm. Whereas (A) a calcined product obtained by firing a raw material powder mixture of a lithium compound, a magnesium compound, Al ₂ O ₃ and SiO ₂ and pulverizing it to a predetermined particle size (B) ) Bi ₂ O ₃ powder was added and mixed, formed into a predetermined shape, and then fired at a predetermined temperature. According to this method, the effect of suppressing the reactivity of the main phase and reducing the grain size during sintering can be expected as compared with the method of Patent Document 4.

JP 2000-188017 A JP-A-2-229760 Japanese Patent Publication No.53-9605 JP 2009-263189 A

  An object of the present invention is to solve the problems of the above-mentioned high strength low temperature firing low thermal expansion porcelain of Patent Document 4 by the present inventors, and is a highly reliable porcelain as a material for a multilayer substrate, including Ag, Au, Cu The present invention provides a low-temperature-fired low-thermal-expansion ceramic that can be fired at the same time as a low-resistance metal such as low-temperature-expandable and can be anodically bonded, and a method for manufacturing the same.

The inventors of the present invention observed the porcelain obtained by the method of Patent Document 4 having a bending strength of 250 to 300 MPa using a scanning electron microscope (SEM), and the grain size was about 2 μm. It has been found. Although it can be expected that the strength is improved by making the grain size finer, Bi ₂ O _{3 as} a sintering aid forms an active liquid phase, and the reaction (growth of particles) proceeds. Therefore, although the calcination temperature was raised for the purpose of reducing the reactivity, no effect was observed (see Reference Example 4 described later). Next, when the particle size after calcination pulverization was increased, the grains were slightly refined but the strength was reduced (see the same reference example 3).

Therefore, an attempt was made to suppress particle growth by reducing the amount of Bi ₂ O ₃ blended (reducing reactivity). When Bi ₂ O ₃ was not blended, the particle size after calcination pulverization was not sintered when the particle size was 0.80 μm or more, but the particle size after calcination pulverization was refined to 0.3 to 0.4 μm. However, the sintered body was densified, the grain size was refined to 1 to 1.5 μm, the bending strength was improved to 300 to 330 MPa, and a stable result was obtained.
The present inventors have completed the present invention based on the above findings.

That is, the present invention relates to the following high-strength low-thermal-expansion ceramic manufacturing method and high-strength low-thermal-expansion ceramic.
[1] (A) Li ₂ O or a lithium compound (a1) that becomes Li ₂ O when fired, MgO or a magnesium compound (a2) that becomes MgO when fired, Al ₂ O ₃ (a3), and SiO ₂ A mixture of (a4) and the mass ratio of a1, a2, a3 and a4: a1: a2: a3: a4 = 7.0-14.0: 4.0-15.0: 12.0-24 0.0: 99.0 to 100 mass of calcined powder obtained by firing a raw material powder mixture in the range of 59.0 to 73.0 at a temperature of 750 to 1000 ° C. and finely pulverizing to an average particle size of 0.3 to 0.8 μm % (B) Bi ₂ O ₃ powder 0 to 1.0 mass% is added and mixed, a molding aid containing a binder is added to form a predetermined shape, and then calcined at a temperature of 900 to 1000 ° C. (1)
(Wherein, a is a mass ratio of 0 to 0.01, and α, β, γ and δ are molar ratios satisfying the mass ratio of a1: a2: a3: a4)
A method for producing a high-strength, low-thermal-expansion ceramic, characterized in that a composite oxide having the composition shown in FIG.
[2] The method for producing a high-strength low-thermal-expansion ceramic according to item 1, wherein Li ₂ CO ₃ , MgO, Al ₂ O ₃ , SiO ₂ , and Bi ₂ O ₃ are used as the raw material powder.
[3] The method for producing a high-strength low-thermal-expansion ceramic according to item 1 or 2, wherein the average particle diameter of each raw material powder is 0.3 to 2.0 μm.
[4] The method for producing a high-strength low-thermal-expansion ceramic according to item 1 above, wherein a green sheet for forming an insulating layer formed by a tape forming method is fired.
[5] Formula (1) obtained by the method according to any one of 1 to 4 above
(The meanings of the symbols in the formula are as described in the preceding item 1.)
A high-strength, low-thermal-expansion porcelain containing a composite oxide having a composition represented by:
[6] The composite oxide comprises a β-spodumene crystal phase and / or a Li ₂ O.Al ₂ O ₃ .SiO ₂ crystal phase, a Li ₂ O.SiO ₂ crystal phase, and an MgO.SiO ₂ crystal. 6. The high-strength low-thermal-expansion porcelain according to item 5 including a phase.
[7] β-spodumene-based crystal phase and / or Li ₂ O.Al ₂ O ₃ .SiO ₂ -based crystal phase, Li ₂ O.SiO ₂ -based crystal phase, and MgO.SiO ₂ -based crystal phase are added to the entire porcelain. 7. The high-strength, low-thermal-expansion porcelain according to the item 6, which contains 95% or more of the product.
[8] The high-strength low-thermal-expansion ceramic according to any one of items 5 to 7, wherein the bending strength is 150 MPa or more.
[9] The high-strength low-thermal-expansion ceramic according to any one of items 5 to 8, wherein the linear thermal expansion coefficient at 25 to 400 ° C. is 0 to 5 × 10 ⁻⁶ / ° C.
[10] The high-strength, low-thermal-expansion ceramic according to any one of items 5 to 9 above, wherein anodic bonding at a temperature of 260 to 350 ° C. is possible, in which conductive ions at the time of anodic bonding are Li ions.
[11] The high-strength low-thermal-expansion ceramic according to item 10, which can be anodically bonded to silicon, GaAs, Kovar, Al, or Ti.

The low-strength, high-strength, low-temperature-expandable porcelain of the present invention comprises Li ₂ O or a lithium compound (a1) that becomes Li ₂ O when fired and MgO or a magnesium compound (a2) that becomes MgO when fired and Al _By calcining the raw material powder mixture composed of ₂ O ₃ (a3) and SiO ₂ (a4) at a temperature of 750 to 1000 ° C., the calcined product is pulverized to an average particle size of 0.3 to 0.8 μm, thereby obtaining a liquid. The amount of Bi ₂ O ₃ used as a phase forming component is reduced, and the β-spodumene crystal phase and / or the Li ₂ O.Al ₂ O ₃ .SiO ₂ crystal phase, the Li ₂ O.SiO ₂ crystal phase This was realized as a porcelain having a MgO.SiO ₂ crystal phase as a main phase. The low thermal expansion ceramic according to the present invention can be sintered at a low temperature of 900 to 1000 ° C., and can form a wiring made of Cu, Au, Ag or the like by simultaneous firing. Therefore, low thermal expansion LTCC (Low Temperature Co-fired Ceramics) A low-temperature co-fired ceramic) substrate. Furthermore, since anodic bonding to silicon or the like is possible at a temperature of 260 to 350 ° C., it is also useful as a substrate for mounting MEMS (Micro Electro Mechanical Systems).

a to f are scanning electron microscope (SEM) photographs of porcelain for multilayer substrates sintered in Reference Examples 1 to 4, 6 and 8, respectively.

[High-strength, low-thermal-expansion porcelain]
The low-strength, high-strength, low-temperature-expandable porcelain of the present invention is
(A) Li ₂ O or lithium compound (a1) that becomes Li ₂ O when fired, MgO or magnesium compound (a2), Al ₂ O ₃ (a3), and SiO ₂ (a4) that becomes MgO when fired The ratio of a1, a2, a3, and a4 (mass% ratio) a1: a2: a3: a4 = 7.0-14.0: 4.0-15.0: 12.0-24 0.0: 99.0 to 100 mass of calcined powder obtained by firing a raw material powder mixture in the range of 59.0 to 73.0 at a temperature of 750 to 1000 ° C. and finely pulverizing to an average particle size of 0.3 to 0.8 μm % (B) Bi ₂ O ₃ powder 0 to 1.0 mass% is added and mixed, a molding aid containing a binder is added to form a predetermined shape, and then calcined at a temperature of 900 to 1000 ° C. (1)
(Wherein, a is a mass ratio of 0 to 0.01, and α, β, γ and δ are molar ratios satisfying the mass ratio of a1: a2: a3: a4). It is manufactured by the method characterized by forming the complex oxide which has this.

A raw material powder mixture (a mixture of a1, a2, a3, and a4) containing Li, Mg, Al, and Si is fired at a temperature of 750 to 1000 ° C., and an average particle size of 0.3 to 0.8 μm, preferably the calcined product from 99.0 to 100% by weight of finely divided into 0.3 to 0.5 [mu] m, by weight of (0 to 1.0% by weight of) Bi ₂ O ₃ powder traces, 900 to 1000 ° C. Sintering (firing densification) can be performed at a low temperature.

  In the general formula (1), the average particle size of the calcined product obtained by firing a raw material powder mixture (a mixture of a1, a2, a3, and a4) containing Li, Mg, Al, and Si at a temperature of 750 to 1000 ° C. If it is less than 0.3 μm, the moldability is remarkably deteriorated, and if it exceeds 0.8 μm, the sinterability is lowered.

In the general formula (1), Bi ratio a (mass ratio) of the ₂ O ₃ is 0 (i.e., Bi ₂ if O ₃ not added) to the narrow appropriate firing temperature range band disadvantage (nine hundred to nine hundred and twenty ° C.) However, by adding a very small amount of Bi ₂ O ₃ of 0.1% or less, the firing temperature range is widened to 900 to 1000 ° C., which facilitates production.

In the general formula (1), the ratio a1 (mass%) of Li ₂ O is 7.0 to 14.0, the ratio a2 (mass%) of MgO is 4.0 to 15.0, and Al ₂ O ₃ ratio of a3 (mass%) is from 12.0 to 24.0, the ratio of SiO ₂ a4 (mass%) is from 59.0 to 73.0. If the value of a1 is less than 7.0, sintering will not occur, and if it exceeds 14.0, it will melt. If the value of a2 is less than 4.0, sintering does not occur, and if it exceeds 15.0, thermal expansion increases. If the value of a3 is less than 12.0, thermal expansion increases, and if it exceeds 24.0, sintering does not occur. If the value of a4 is less than 59.0, it will not sinter, and if it exceeds 73.0, it will not sinter.

The main raw materials, Li ₂ O or a lithium compound that becomes Li ₂ O when fired, MgO or a magnesium compound that becomes MgO when fired, Al ₂ O ₃ , and SiO ₂ are metal oxides. A mixture of MgO and a complex oxide such as β-spodumene may be used. Li ₂ O that can be used as a starting material or a lithium compound that becomes Li ₂ O when fired, MgO or a magnesium compound that becomes MgO when fired, Al ₂ O ₃ , and SiO ₂ are each of the above metals In addition to the oxide powder, a salt capable of forming an oxide during the sintering process, such as carbonate, acetate, nitrate, hydroxide, etc., such as lithium carbonate (Li ₂ CO ₃ ), magnesium carbonate (MgCO ₃ ) or magnesium hydroxide (Mg (OH) ₂ ).

By adding a small amount of Bi ₂ O ₃ powder as a sintering aid to the main raw material, the sintering temperature range is expanded.

Raw material powders such as Li ₂ CO ₃ , MgO, Al ₂ O ₃ , SiO ₂ and Bi ₂ O ₃ have an average particle size of 0.3 to 2 in order to increase dispersibility and obtain desirable strength and low thermal expansion. It is desirable to use a fine powder of 0.0 μm, preferably 0.5 to 1.0 μm. When the average particle size is less than 0.3 μm, handling such as dispersion is difficult, and when it exceeds 2.0 μm, the reactivity decreases. It is preferable from the viewpoint of uniformity of mixing that the raw materials have uniform particle diameters.

Addition and mixing at the above ratio, after calcining at 750 to 1000 ° C., a small amount of Bi ₂ O ₃ powder is added to the mixed powder pulverized to an average particle size of 0.3 to 0.8 μm, and a binder, preferably an organic binder, For example, after adding an organic solvent such as toluene or methyl ethyl ketone (MEK) as necessary, such as an acrylic resin binder or the like, or a plasticizer such as a polyester resin such as dibutyl phthalate (DBP), for example, a die press, After molding into an arbitrary shape by extrusion molding, doctor blade method, rolling method, etc., firing in an oxidizing atmosphere or a non-oxidizing atmosphere such as nitrogen gas or argon gas at a temperature of 900 to 1000 ° C. for 1 to 3 hours By doing so, it can be densified to a relative density of 95% or more.

  If the firing temperature at this time is lower than 900 ° C., the porcelain will not be sufficiently densified, and if it exceeds 1000 ° C., densification is possible, but low melting point conductors such as Ag, Au, Cu, etc. should be used as the wiring material. Becomes difficult.

The high-strength, low-thermal-expansion porcelain of the present invention has the formula
(The symbols in the formula have the same meaning as described above.)
A composite oxide having a composition represented by:

High-strength and low-thermal-expansion ceramic according to the present invention, beta-spodumene based crystal phase and / or _{Li 2 O · Al 2 O 3} · SiO 2 type crystal phase, Li ₂ O · SiO ₂ type crystal phase, and MgO · SiO ₂ Mainly composed of a system crystal phase, and further mainly composed of a Bi ₂ O ₃ .SiO ₂ system crystal phase or / and a glass phase.

Here, “β-spodumene-based crystal phase” means a β-spodumene crystal and a crystal phase having a composition and a crystal structure similar to this, and “Li ₂ O.Al ₂ O ₃ .SiO ₂ -based crystal phase” means Li ₂ O.Al ₂ O ₃ .SiO ₂ crystal and a crystal phase of a composition and crystal structure similar to this, “Li ₂ O.SiO ₂ crystal phase” means a Li ₂ O.SiO ₂ crystal and a similar composition and Each of the crystal phases may include a crystal having the same type of crystal structure including elements other than the main constituent elements constituting each of the crystals.

The same applies to the MgO · SiO ₂ crystal phase and the Bi ₂ O ₃ · SiO ₂ crystal phase. The term “MgO · SiO ₂ crystal phase” refers to an MgO · SiO ₂ crystal and a similar composition and crystal structure. The “Bi ₂ O ₃ .SiO ₂ -based crystal phase” is a crystal phase of Bi ₂ O ₃ .SiO ₂ crystal and crystal structure, and each crystal phase includes the above crystals. A crystal having the same type of crystal structure including other elements than the main constituent element may be included.

The specific content ratio of each crystal phase is not particularly limited as long as it achieves a target physical property value. Usually, the β-spodumene crystal phase and / or Li ₂ O.Al ₂ O ₃ .SiO _{2 is used. The two} -phase crystal phase, the Li ₂ O.SiO ₂ -based crystal phase, and the MgO.SiO ₂ -based crystal phase include 95% or more, preferably 98% or more, of the total volume of the porcelain.

The high-strength low thermal expansion ceramic of the present invention has a linear thermal expansion coefficient of 0 to 5 × 10 ⁻⁶ / ° C., a bending strength of 150 MPa or more, and a relative density of 95 by low-temperature firing in a temperature range of 900 to 1000 ° C. % Densified.

[Applications of low thermal expansion ceramics]
According to the present invention, it can be fired at a low temperature of 900 to 1000 ° C., and can be fired simultaneously with a low melting point / low resistance conductor such as Ag, Au, Cu, etc., and the resulting porcelain has a room temperature (RT = 25 ° C.). The linear thermal expansion coefficient at ˜400 ° C. is as small as 0 to 5 × 10 ⁻⁶ / ° C.

  That is, the porcelain of the present invention can be fired at a low temperature of 900 to 1000 ° C., so that it can be used as an insulating substrate of a wiring substrate for wiring Ag, Au, Cu or the like.

When producing a wiring board using such a composition for porcelain of the present invention, for example, a mixed powder of Li ₂ O, MgO, Al ₂ O ₃ and SiO ₂ and Bi ₂ O ₃ powder prepared as described above. In accordance with a known tape molding method, for example, a doctor blade method, an extrusion molding method, etc., a green sheet for forming an insulating layer is prepared, and at least one of Ag, Au, and Cu is used as a wiring circuit layer on the surface of the sheet. Using a conductive paste containing one kind of metal, particularly Ag powder, a wiring pattern is printed on the surface of the green sheet by a screen printing method or the like. In some cases, after forming a through hole or via hole on the sheet, the conductor Fill with paste. Thereafter, the plurality of green sheets are laminated and pressure-bonded, and then fired under the above conditions, whereby the wiring layer and the insulating layer can be fired simultaneously.

[Anodic bonding]
The high-strength, low-thermal-expansion porcelain of the present invention is capable of anodic bonding, which is a bonding technique essential for the production of MEMS (Micro Electro Mechanical Systems) mounting substrates.

  In anodic bonding, a silicon containing porcelain containing alkali metal is in contact with silicon and heated to a temperature at which ant potassium metal ions such as sodium in the porcelain easily move, and the silicon side is connected to the positive electrode and the porcelain side is connected to the negative electrode. This is a method of joining porcelain and silicon by applying a DC voltage of about several hundred to 1,000 volts. Non-bridging oxygen ions generated when alkali metal ions move to the negative electrode side and silicon are electrostatically attracted to form a chemical bond at the porcelain-silicon interface, whereby a strong and reliable bond can be obtained.

The temperature at which the anodic bonding is performed is preferably a low temperature of 350 ° C. or less that has little influence on the MEMS, and a low bonding temperature of, for example, 260 to 330 ° C. or less is particularly suitable.
The high-strength, low-thermal-expansion porcelain of the present invention has a suitable temperature range (300 to 350 ° C.) that has little influence on MEMS by changing the conductive ions at the time of anodic bonding from conventional Na to Li having a smaller ion radius. ) Anodic bonding is possible.

  The anodic bonding can bond not only silicon but also GaAs, Kovar, Al, Ti and the like, and is not particularly limited in the porcelain of the present invention.

In anodic bonding, misalignment due to thermal expansion with the counterpart material becomes a problem, so the linear thermal expansion coefficient of the substrate material is required to approximate the linear thermal expansion coefficient of the counterpart material. The linear thermal expansion coefficient of the material is preferably within 0.5% of the linear thermal expansion coefficient of the counterpart material. If the counterpart material is silicon, the linear thermal expansion coefficient of porcelain of the invention, 0 to 5.0 × 10 ^-6 / ° C., preferably 3.0~4.0 × 10 ^-6 / ℃, more preferably Is 3.2 to 3.8 × 10 ⁻⁶ / ° C., particularly preferably 3.2 to 3.5 × 10 ⁻⁶ / ° C.

  Hereinafter, the present invention will be described in more detail with reference to reference examples, examples, and comparative examples, but these do not limit the present invention.

Reference Examples 1-8:
As a preliminary experiment, the composition of Example 5 of Patent Document 4 was examined with the aim of improving the bending strength.
That is, as shown in Reference Examples 1 to 8 in Table 1, Li ₂ CO ₃ , MgO, Al ₂ O ₃ and SiO ₂ having an average particle diameter of 1 μm or less are contained in terms of oxide (molar ratio = 2: 1: 1: 9)
, Mixed in a ball mill such that (1-a) has a composition of 1 and 0.95, held at 790 to 880 ° C. for 3 hours and calcined, and then pulverized to each average particle size (D ₅₀ ) Sample powder was obtained. Bi ₂ O ₃ is added to these calcined materials at the ratio shown in Table 1, an organic binder (polyvinyl alcohol), a plasticizer (dibutyl phthalate), and toluene are added and mixed, and a green sheet having a thickness of 150 μm is obtained by a doctor blade method. It was created. Five green sheets were laminated and thermocompression bonded by applying a pressure of 150 kg / cm ² at a temperature of 70 ° C. The obtained laminate was debindered at 500 ° C. in the air, and then fired in the air for 1 hour under the temperature conditions shown in Table 1 to obtain a multilayer substrate porcelain.

About the obtained sintered bodies of Reference Examples 1 to 4, 6 and 8, the grain size, water absorption (mass A of the sample in an absolute dry state and mass B of the surface dry saturated state were measured, and {(BA ) ÷ A} × 100.), Bulk density (according to Archimedes method), porcelain three-point bending strength (deflection strength) (according to JISR1601), fracture toughness value (according to IF method), linear thermal expansion coefficient ( Room temperature to 400 ° C., measured by TMA (thermomechanical analysis) method. These results are shown in Table 1.
The grain size was determined by the intercode method from a photograph taken with a scanning electron microscope (SEM). The reflected electron images obtained by the SEM as the basis are shown in FIGS.

In Reference Examples 1 and 2 in which 5% Bi ₂ O ₃ was blended with calcined powder having an average particle size of 0.32 to 0.48, the grain size was 2.1 to 2.2 μm and the bending strength was 274 to 293 MPa. Met. The calcining temperature was raised to reduce the reactivity (particle growth) with the sintering aid (Bi ₂ O ₃ ) with the aim of reducing grain size (improving strength), but no effect was observed. (Reference Example 4).
When the particle size after calcination pulverization was increased, the grains were slightly refined, but the strength decreased (see Reference Example 3).
Attempts were made to suppress particle growth by reducing the amount of Bi ₂ O ₃ to zero. When Bi ₂ O ₃ was not blended, sintering did not occur when the particle size after calcination pulverization was 0.80 μm or more (Reference Examples 5 and 7), but the particle size after calcination pulverization was 0.31 to 0.31. When the size was reduced to 0.40 μm, the sintered body was densified, the grain size was reduced to 0.9 to 1.4 μm, and the bending strength was improved to 303 to 329 MPa.

Examples 1-6 and Comparative Examples 1-7:
Li ₂ CO ₃ , MgO, Al ₂ O ₃ , and SiO ₂ having an average particle size of 1 μm or less were mixed in a ball mill so that the content ratio in terms of oxide was the ratio shown in Table 2, and temporarily mixed at 750 to 1000 ° C. After firing, it was pulverized to each particle size to obtain a sample powder. Bi ₂ O ₃ is added to these calcined materials in the ratio shown in Table 2, an organic binder (polyvinyl alcohol), a plasticizer (dibutyl phthalate), and toluene are added and mixed, and a green sheet having a thickness of 150 μm is formed by a doctor blade method. Created. Five green sheets were laminated and thermocompression bonded by applying a pressure of 150 kg / cm ² at a temperature of 70 ° C. The obtained laminate was debindered at 500 ° C. in the air, and then fired in the air for 1 to 3 hours under the temperature conditions shown in Table 2 to obtain a multilayer substrate porcelain.

  The bulk density of the obtained sintered body was measured by the Archimedes method. Moreover, based on JISR1601, the three-point bending strength (bending strength) of the porcelain was measured, and the linear thermal expansion coefficient from room temperature (RT = 25 ° C.) to 400 ° C. was measured by the TMA (thermomechanical analysis) method. Further, X-ray diffraction measurement was performed for each sample, and the constituent phases of the porcelain were identified by comparison with the X-ray diffraction peak of the standard sample. These measurement results are shown in Table 2.

In Table 1, Lithium Silicate, Lithium Aluminum Silicate, Enstatite, Bismus Silicate, and Forsterite each represent the following crystal phase.
Lithium Silicate: Li ₂ SiO ₃ , Li ₂ Si ₂ O ₅ etc.
Lithium Aluminum Silicate: Spodumene (LiAlSi ₂ O ₆ ), etc.
Enstatite: MgSiO ₃
Bismus Silicate: Eulytite, Bi ₂ O ₂ · SiO ₃ etc.
Forsterite: Mg ₂ SiO ₄ .

As described in the column of the crystal phase in Table 2, for the porcelain of the example, the β-spodumene crystal phase and / or the Li ₂ O.Al ₂ O ₃ .SiO ₂ crystal phase, Li ₂ O.SiO ₂ The existence of each phase of the system crystal phase and the MgO.SiO ₂ system crystal phase was confirmed.

As is apparent from the results shown in Table 2, Li ₂ O, MgO, Al ₂ O ₃ , SiO ₂ are included in the composition range of the present invention, and the β-spodumene crystal phase and / or Li ₂ O. The low-temperature fired ceramics of the present invention in which the Al ₂ O ₃ · SiO ₂ crystal phase, Li ₂ O · SiO ₂ crystal phase, and MgO · SiO ₂ crystal phase are mainly precipitated have a linear thermal expansion coefficient of 0 to 5 respectively. × 10 ^-6 / ° C low thermal expansion porcelain.

[Confirmation of anodic bonding]
The substrate 6 level sintered in the examples was prepared, and the anodic bonding performance was evaluated. Each of the six substrates and each one was diced to 20 mm □ and polished to a mirror thickness of 0.3 mm. On this hot plate where the substrate and silicon were heated, anodic bonding was performed by applying a DC voltage (600 VDC) so that silicon was a positive electrode and the substrate was a negative electrode. A resistance element for voltage detection was inserted on the anode junction circuit, and the voltage applied to the resistance element was monitored to check how the junction current changed with the junction time.
Although the surface roughness (Ra: centerline average roughness) of the baked substrate was about 200 nm, in the present invention, by increasing the mirror polishing level, Pyrex (registered trademark) glass (product) Name: Finished to a surface roughness (several nmRa) equivalent to Corning Borosilicate Glass). Using this mirror-polished substrate, anodic bonding was performed at 260, 300 ° C., 330 ° C., and 360 ° C.
The obtained anodic bonded body was scratched with glass and divided by hand, and the fractured surface was observed with SEM. As shown in Table 3, the results show that the silicon and the low-temperature sintered substrate have a continuous fracture surface at all levels, and there is no discontinuity (delamination), and it is observed that they are firmly bonded (OK). It was.

For comparison, delamination was confirmed for a bonded body obtained by anodically bonding silicon with low-temperature fired ceramics using Na as a conductive ion during anodic bonding. The LTCC for comparison was produced as follows.
That is, the glass powder which is commercially available as a glass capable of anodic bonding (SiO _2: 81.9 to 82.4 wt%, Al ₂ O _3: 2.9~3.2 wt%, B ₂ O _3: 10.5 ˜11.0 mass%, Na ₂ O: 3.9 to 4.7 mass%, K ₂ O, Fe ₂ O ₃ , CaO, and MgO are all 0.1 mass% or less) 55 to 60 mass% averaged ground to 0.6~2.5μm with particle size (D _50), the average particle diameter 1~3μm of alumina powder 8-25 mass% and an average particle size 1~3μm cordierite powder (glass recrystallized type) 18 Mixed with ~ 34% by weight. Toluene was added as a solvent to this mixture and dispersed in a ball mill, and then polyvinyl alcohol as a binder and dibutyl phthalate (DBP) as a plasticizer were added to prepare a slurry. The obtained slurry was formed into a sheet by a doctor blade method and dried to obtain a green sheet having a thickness of 125 μm. This is cut into a predetermined size, laminated into 8 layers, fired at 835 ° C. or 850 ° C. for 1 hour in the air, and glass / filler composite LTCC (BSW) using Na as a conductive ion at the time of anodic bonding. Produced. This substrate (BSW) could not be anodically bonded at 330 ° C. (NG).

  As described above, according to the porcelain of the present invention in which the conductive ions at the time of anodic bonding are Li ions, compared to the conventional low-temperature fired ceramics (LTCC) using Na ions as the conductive ions at the time of anodic bonding, 350 ° C. or less. Anodic bonding is possible even at low temperatures.

According to the present invention, sintering can be performed at a temperature of 900 to 1000 ° C., and simultaneous firing with a low melting point / low resistance conductor such as Ag, Au, Cu, etc. is possible. RT = 25 ° C.) The low thermal expansion ceramic of the present invention having a linear thermal expansion coefficient of as small as 0 to 5 × 10 ⁻⁶ / ° C. at 400 ° C. can be provided. That is, the porcelain of the present invention can be sintered at a temperature of 900 to 1000 ° C., and therefore can be used as an insulating substrate of a wiring substrate for wiring Ag, Au, Cu and the like. Further, anodic bonding is possible at a temperature of 260 to 350 ° C., and it is useful as a substrate for mounting MEMS (Micro Electro Mechanical Systems).

Claims (9)

(A) Li ₂ O or lithium compound (a1) that becomes Li ₂ O when fired, MgO or magnesium compound (a2), Al ₂ O ₃ (a3), and SiO ₂ (a4) that becomes MgO when fired The ratio α of the lithium compound (a1) is 7.0 to 14.0% by mass in terms of Li ₂ O, and the ratio β of the magnesium compound (a2) is 4.0 to 15 in terms of MgO. Raw material powder mixture in which 0% by mass, Al ₂ O ₃ (a3) ratio γ is 12.0 to 24.0% by mass, and SiO ₂ (a4) ratio δ is 59.0 to 73.0% by mass. Is then calcined at a temperature of 750 to 1000 ° C. and finely pulverized to an average particle size of 0.39 to 0.58 μm, and a molding aid containing a binder is added to form a predetermined shape, and then the temperature is 900 to 920 ° C. Baked in the formula (1 ')
(Wherein, α, β, γ, and δ are molar ratios satisfying the mass ratio of a1: a2: a3: a4), and a composite oxide having a composition is formed. The manufacturing method of the high intensity | strength low thermal expansible ceramic whose bending strength is 150 MPa or more and whose linear thermal expansion coefficient in 25-400 degreeC is 0-5 * 10 < ^-6 > / degreeC. Wherein as the raw material _{powder, Li 2 CO 3, MgO,} Al 2 O 3 and the method of producing a high-strength and low-thermal-expansion ceramic according to claim 1, wherein the use of SiO _2.   The method for producing a high-strength, low-thermal-expansion ceramic according to claim 1 or 2, wherein an average particle diameter of each raw material powder is 0.3 to 2.0 µm.   The method for producing a high-strength, low-thermal-expansion ceramic according to claim 1, wherein a green sheet for forming an insulating layer formed by a tape forming method is fired. Formula (1 ') obtained by the method according to any one of claims 1 to 4.
(In the formula, α, β, γ and δ have the same meaning as described in the formula (1 ′) of claim 1).
A high-strength, low-thermal-expansion porcelain having a flexural strength of 150 MPa or more and a linear thermal expansion coefficient at 25 to 400 ° C. of 0 to 5 × 10 ⁻⁶ / ° C., including a composite oxide having a composition represented by: The composite oxide includes a β-spodumene crystal phase and / or a Li ₂ O · Al ₂ O ₃ · SiO ₂ crystal phase, a Li ₂ O · SiO ₂ crystal phase, and an MgO · SiO ₂ crystal phase. The high-strength low-thermal-expansion ceramic according to claim 5. The β-spodumene-based crystal phase and / or the Li ₂ O.Al ₂ O ₃ .SiO ₂ -based crystal phase, the Li ₂ O.SiO ₂ -based crystal phase, and the MgO.SiO ₂ -based crystal phase are 95% of the total volume of the porcelain. The high-strength low-thermal-expansion porcelain according to claim 6 containing at least%. The high-strength low-thermal-expansion ceramic according to any one of claims 5 to 7 , wherein anodic bonding is possible at a temperature of 260 to 350 ° C, wherein the conductive ions at the time of anodic bonding are Li ions. The high-strength, low-thermal-expansion porcelain according to claim 8, capable of anodic bonding with silicon, GaAs, Kovar, Al, or Ti.