JPS61155253A - Mgo sintered body for insulation base material and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an MgO sintered body as an insulating base material, and more particularly, to an MgO sintered body for an electrically insulating base material having high thermal conductivity and excellent hydration resistance, and its production. It is about law.

Most of the insulating materials currently used in IC substrates, which are electronic materials, are Ah03 substrates.

On the other hand, MgO base material has excellent electrical insulation properties at high temperatures, and has better high frequency properties and thermal conductivity than Al703 base material, so it is expected to be used as this type of integrated circuit board material. As a result, it has not been possible to obtain a material that has high hydration properties and sufficient strength, so the actual situation is that the above characteristics cannot be fully utilized and it has not been put into practical use.

The present invention is based on the viewpoint that, even under these circumstances, the characteristics of the MgO base material will be extremely effective in the development of future highly functional IC substrates, such as the development of hybrid ICs and laminated packages. As a result of various studies, we have succeeded in developing a sintered body that provides an MgO substrate that has improved the above-mentioned drawbacks such as hydration, which had been a major obstacle to practical application.

That is, in the present invention, most of the MgO crystal particles have a size of 5 mm or less when viewed microscopically, and at least
It consists of a structure in which the 2MgO・Si02 phase is evenly distributed as a thin layer between the O crystal grains, and the thermal conductivity is 0.08 cal/cm sec*"C or more at room temperature.
Preferably, the dielectric constant at 100 KHz is 10 at room temperature.
Below, the dielectric loss (Tan δ) at 100KH2 is 3X10-4 or less at room temperature but exceeds lXl0-4, and the molded insulation resistance is lQI OΩ・cff at 300℃.
This is an MgO sintered body for insulating base materials, which is characterized by having an excellent hydration resistance property of at least MgO.
Fine MgO crystals are formed by thoroughly mixing MgO powder with a purity of gO of 99% or more by weight as a chemical analysis value and a specific surface area of 10 rn'/g or more in an organic solvent containing an organic silicate, followed by shaping and firing. 2MgOΦ between particles
Consists of a structure in which SiO2 phase is evenly distributed, and has a thermal conductivity of 0.08 cal/cms sec at room temperature.
/'O or more Electrical insulation resistance is 1010Ω at 300℃
The gist of the present invention is to provide a method for producing an MgO sintered body for an insulating base material, which is characterized in that the MgO sintered body has a hydration resistance of at least cm and has excellent hydration resistance.

As described above, the present invention has extremely excellent characteristics as an MgO sintered body for insulating substrates, and the structure of the sintered body that makes these characteristics possible is that of fine MgO crystal (periclase crystal) particles and between them. 2MgOφSi[l? (forftilite) as the main phase (hereinafter referred to as 2) 4g [l・5
It is thought that this is essentially caused by the presence of the iD2 phase) as a thin layer.

In the past, 2MgO・S was developed as an MgO substrate.
There have been several attempts and proposals to add water resistance by forming a coating layer of i07 phase, but
It had not achieved sufficient results.

Although it is not clear why the results of such past attempts did not result in satisfactory physical properties, it is essentially due to the differences in the fine structure and structure of the sintered body and the differences in the manufacturing method that bring about these differences. This may be due to this.

For example, one of the major reasons for this is that most of the conventional proposals of this kind, as disclosed in Japanese Unexamined Patent Publication No. 58-217480, have processed pre-formed substrates to make them water-resistant.
It is also considered that this was an attempt to form an O.SiO2 phase.

In other words, products made using such methods may not have sufficient water resistance, or may not have sufficient thermal conductivity.
In particular, it has not been possible to obtain a substrate that combines the various properties that make a highly functional substrate possible.

As another method, JP-A-58-181784 proposes mixing a magnesium compound and a liquid silicon compound such as a sodium silicate solution in order to obtain a dense sintered body, but I haven't reached the point where I have sex.

The reason for this is not clear, but since the sintered body targeted by the patent is translucent, the liquid silicon compound must be limited to a small amount, and whether it is related to this. I don't know, but before molding the mixture, it is 750~
It is conceivable that preliminary heat treatment at 1100° C. must be performed.

Regarding the sintered body of the present invention and its manufacturing method, if it is obtained by at least partially covering the individual surfaces of the MgO crystal particles located below, it is possible to completely obtain the sintered body and its manufacturing method. It is not necessary to be something,
Considering some properties such as thermal conductivity, 2MgO
・On the other hand, the presence of SiO2 phase may be small; in short, 2
It is sufficient that the MgO.SiO2 phase is distributed evenly in the cross-sectional structure of the sintered body, even if it is at least locally, rather than all around the individual M&0 particles. In the tree specification, uniform refers to such a structure.

In addition, the same structure can be considered at the so-called interface between MgO particles, where the particles should come into contact with each other. Solidarity is also one of the desirable things.

In such a sintered body of the present invention, this 2MgO・Si
The O2 phase exists between the MgO particles (including the interface) as a thin layer, and preferably the thickness is less than 0.5 yL, for example, about 0.1 to 0.5 yL. be.

In addition, this 2MgO・SiO2 phase is produced by SiQ of MgO fine powder and organic silicate, as shown in the production method described below.
Since it is produced by reacting with two components, it is originally Mg.
It often exists as an integral part on the surface of O particles.

Here, the sintered body of the present invention will be further explained in more detail with reference to microphotographs.

In the first round, 1 is MgO particles, 2 and 3 are 2MgO
It is LISiO2 phase.

In this way, Mg[1 particles 1 are tightly sintered through the 2MgO◆Si[12 phases 2 and 3, and most of them have a particle size of 5 or less. I understand.

It is also seen that the MgO*SiO2 phase exists not only between Mg particles 5 but also at the interface 6 between MgO particles.

Incidentally, some particles in the sintered body have a grain size of about 5 to 10 #L, but their purity is at most 20% by weight or less, and usually about 10% or less. be.

Here, 2MgO・SiO7 phase 2 covers the MgO particles (i.e., exists at the grain boundaries) 2MgO・S
It is an i07 phase, and 3 exists between a plurality of MgO particles and a 2MgOe SiO2 phase.

In addition, in the present invention, such 2MgO・S i02
The phase has a volume ratio of about 3% or more, preferably 5 to 8%.
It is desirable that the amount of

In order for the sintered body of the present invention to have the desired properties, it must be made by densely sintering high-purity MgO, and in terms of composition, the MgO purity of the MgO crystal particles is determined as a chemical analysis value. MgO is 99.5% or more in terms of %”-1, especially 9
It is desirable that it be 9.7% or more. In this specification, the purity of this MgO particle refers to the 2M produced on its surface.
g Refers to the purity of the part excluding the O・SiO2 phase.

In addition, as for the composition of the sintered body as a whole, as a chemical analysis value, Si02 is 0.1 to 5% by weight, and from the viewpoint of hydration resistance, it is 0.5 to 3%, and as a concentration of SiO2 and MgO. It is desirable that it be 99.5% or more, particularly 99.7% or more.

The sintered body having such a structure and composition is characterized as having the following characteristics as the present invention. Note that the values in parentheses are more desirable ranges.

Bulk density 3.
4 (3,45) or higher 1-Flexible strength (at room temperature, kg/m
rn') 20 (25) or more thermal conductivity
Room temperature 0.08 (0.10) or more (cat/cm*
see e 'C)300°CO,05(0,06)
-L dielectric constant (room temperature, 100KHz) 1
Dielectric loss below 0 (room temperature, 100KHz) IX
10. -4~3X 10-4 electrical insulation resistance (No. 0 cm
) 1010 or more water availability (?t)
0.02% or less (Note) 150 in autoclave
Weight increase rate when kept in 5 atm steam at °C for 2 hours (
The size of the sample is a plate-shaped body measuring 50 mm x 50 mm x 1 mm thick, but when the thickness is such a thin plate, the size has almost no effect, so it corresponds to the increase rate per unit area.

) As a test method for evaluating reliability as an electrically insulating board, a test is generally used in which the board is left in 120°C and 2 atm water vapor for 500 hours. As a result of testing the sintered body of the present invention using this test method, there was almost no increase in weight.

A manufacturing method for producing such a sintered body of the present invention, particularly a preferred method of the present invention for producing a sintered body of the present invention, will be described below.

First, high purity MgO powder is prepared as the MgO component which is the main raw material.

The MgO powder used here needs to have high purity MgO crystal particles in the sintered body, so the chemical analysis value is extremely high purity in terms of weight percent, specifically 98% or more. , preferably 99.5% or more.

In this way, high-purity MgO powder is highly pure Mg(OHh
can be obtained by calcining, for example, at 800° C. for 2 hours.

In addition, the particle size of the powder used must be fine in order to form a sintered body of fine crystal particles, and specifically, l
It is a fine powder having a specific surface area of 0 rn'/g or more, particularly 20 rn'/g or more.

Next, 2MgO・S i which essentially imparts hydration resistance.
As for the SiO2 component that brings about the 02 phase, it is also desirable to have a combined content of 99.5% or more with MgO as a sintered body, and at the same time, it is desirable to add 28g02 as a thin layer on the surface of each particle of the MgO powder as much as possible. - It has been found that it is desirable to use an organosilicate solution due to the need to generate the S i02 phase.

As the organic silicate, silicate alcoholades such as ethyl silicate, methyl silicate, butyl silicate-1, etc. are suitable, and among them, ethyl silicate is most suitable.

By mixing this organic silicate and high-purity finely powdered MgO, two particles are deposited on the surface of the MgO powder in a powder state by subsequent firing.
It is thought that it will be possible to form a SiO2 coat that can generate the MgO・SiO2 phase, but during this mixing,
Organic silicates such as ethyl silicate are normally highly hygroscopic in air, and they themselves become hydrated, causing the phenomenon of precipitating and separating Si02, making it difficult to achieve the desired surface coating in the form of MgO powder as described above. It is effective to take precautions to prevent ethyl silicate and the like from coming into contact with air.

This can be solved by mixing MgO powder in an organic solvent containing an organic silicate. As an organic solvent, M
Alcohols that do not hydrate with gO are suitable; for example, ethanol is sufficient.

It is believed that by thoroughly mixing MgO powder in a mixed solvent of ethyl silicate and ethanol in this way, it is possible to form a SiO2 coat that provides preferable water resistance on the surface of MgO powder.

Now, regarding the formulation of organic silicate added in the present invention, in order to provide sufficiently excellent water resistance, which is a more preferred embodiment of the present invention, a certain amount of 2MgO is required.
・It was found that a SiO2 phase is required, and for this purpose, as mentioned above, it is preferable that the SiO21 content of the sintered body is at least 0.5% in weight M% as the analytical value of the sintered body. As you can see, the content of SiO2 and MgO is 0.5% or more! It is desirable to have a - hanging.

In addition, if the amount of 5iO2Fil is too large, it will impair other properties necessary for electrically insulating substrates, such as thermal conductivity, so as mentioned above, the amount of 5iO2Fil should be limited to a maximum of 5% by weight as SiO, +jJ in the sintered body. It is necessary to mix them.

The optimum amount of organic silicate is the amount of 5 remaining in the sintered body.
The weight of 102M is 0.8 to 3.

In addition, the ratio of organic silicate to organic solvent is in weight%,
Among these contents, the former is 50-10% and the latter is 50-90%.
%.

Incidentally, the sintered body of the present invention has 2MgO・S i
The bonding state on the surface of the MgO powder that is thought to result in the 02 phase is 1. Before firing, the bonding state of Mg(OH)2 and (C2H5)4 Si,! l: It is thought that 0,021 (5) is reacted with C2Hs-OH.

Next, the mixture in such a state is formed into a predetermined shape, usually a sheet, by a known method such as a doctor blade method or a press method, and is fired to obtain the sintered body of the present invention. What matters is the firing temperature.

In other words, according to the method of the present invention, sintering can proceed easily even when the firing temperature is extremely low. Therefore, the grain growth of MgO crystals can be suppressed, and even low-temperature sintering is possible. This is because a dense sintered body can be obtained.

Specifically, to obtain a dense MgO sintered body, high-temperature firing of 1,600°C or higher is usually required;
According to the present invention, a temperature of 1500°C or lower, particularly 1450°C or lower is usually sufficient, and in many cases, a sufficiently dense sintered body can be obtained even at about 1400°C.

On the other hand, in order to achieve sufficient sintering, the temperature is usually 1300°C or higher.
Preferably, firing at a temperature of 1350°C or higher is effective.

Furthermore, in the method of the present invention, when forming the mixture into a sheet shape, etc., although the mixture may be dried without any preheating treatment, the mixture is directly formed and immediately heated to a predetermined firing temperature. Can be fired.

As described above, the MgO sintered body obtained by the present invention maintains the electrical properties such as strength and electrical insulation properties necessary for use as an electrically insulating MgO base material, takes advantage of the material's characteristic of high-temperature grooves, and overcomes the major drawbacks of the conventional material. This product has succeeded in significantly improving the hydration resistance problem, without requiring special water-resistance treatment after obtaining the sintered body (of course, additional treatment is acceptable and effective). And that T
The commercial value is enormous, such as making the development of high-performance IC boards more possible.

The present invention will be further explained by examples.

Example 99.9% high purity Mg (OHh was calcined at 800'0 for 2 hours to produce Mg with a specific surface area of 30-40 m'/g.
gO powder was obtained.

For 100 g of this MgO powder, ethyl silicate 1-
A mixture of 20 cc of ethanol and 50 cc of ethanol was prepared, and 100 cc of a 12% polyvinyl butyral solution was added as a binder and mixed. This mixture was formed into sheets, one at 1450 °C and the other at 144 °C.
After firing at 0°C for 1 hour, two types of sheet-like sintered bodies with wall thicknesses of 0 and 5 mm were obtained.

The results of microscopic observation and chemical analysis of the cross-sectional structure of this sintered body were as follows.

○ Cross-sectional structure Extremely fine MgO (periclase) crystal grains are sintered in a densely entangled state, and the 2MgO@SiO2 phase is present in most of the spaces between the MgO crystal grains at a volume ratio of about 4 to 5.
%, and a 2MgOΦSiO2 phase was also formed at some of the grain boundaries. The shape of this MgO crystal is approximately circular, and most of its size is l~
5 pL, 2MgO Si (the thickness of the b phase is approximately 0
．． It was about 1 to 0.5 ml.

○ Chemical analysis value (vertical part %) Whole sintered body MgO98.9% SiO2 1. Q% Also, the measurement results of various properties and characteristics of the sintered body are as shown in the following table. (A: 1450°C fired product, B: 1440°C
°C fired products, those without AB description are the same as A) Bulkyden
Degree A, 3.50. B; 3.49 (3
, 40) Flexural strength (kg/mm') Room temperature 2? (24) Thermal conductivity (cal/cm m 5eCe ℃) normal temperature
0.11 (0,07)300℃
o, oe (0,04) permittivity (1
00KH2) Room temperature 9.3 (9,3) Dielectric loss (100KHz) Room temperature A: 1.3 xtol, B: 2.4X1
0-” (2X101) Electrical insulation resistance (06cm) 300℃ 6×10 ports (OX 1011)
Hydration resistance (Note) 0.012% (0.03%) Comparative Example 1 A porous MgO sintered body disclosed in JP-A-58-217480 was impregnated with an organic silicon compound liquid to coat the surface. The data of the MgO sintered body obtained as a result of combustion to form a coating layer mainly composed of 2MgO.SiO2 on the surface is shown in parentheses in comparison with the product of the present invention.

2. Almost the same as in Example, but the molded body obtained by mixing in ethyl alcohol not containing ethyl silicate was insufficiently sintered at 1400°C, so 1.
When attempting to measure the hydration resistance of a sintered body fired at 600° C., it turned into powder and could not be measured.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional micrograph showing a typical example of the sintered body of the present invention. The scale is 31L in l scale. 1 is MgO particles, 2 and 3 are 2MgO.SiO2 phases.

Claims (1)

[Claims] (1) Microscopically, most of the MgO crystal particles have a size of 5 μ or less, and at least a 2MgO.SiO_2 phase is evenly distributed as a thin layer between these MgO crystal particles. It consists of a structure with a thermal conductivity of 0.08ca1/cm・s at room temperature.
Dielectric loss (tan
δ) exceeds 1 x 10^-^4 at room temperature and 3 x 10^-^4
Below, the electrical insulation resistance is 10^1^0Ω・cm at 300℃
An MgO sintered body for electrically insulating base materials, which is characterized by having the above properties and excellent hydration resistance properties. (2) 2M also exists at least partially at the MgO crystal grain interface.
Claim 1 in which gO・SiO_2 phase is present
MgO sintered body as described in section. (3) The chemical analysis value of MgO crystal particles is 99.5 in weight%
% or more of the MgO sintered body according to claim 1 or 2. (4) The MgO sintered body according to claim 1 or 3, which has a bulk density of 3.4 or more. (5) The chemical analysis value as a sintered body is in weight% of SiO
The MgO sintered body according to claim 1 or 4, which contains 0.5 to 5% of SiO_2 and the ratio of SiO_2 and MgO is 99.5% or more. (6) The MgO sintered body according to claim 1, which has a bending strength of 25 kg/mm^2 or more at room temperature. (7) Thermal conductivity is 0.1 cal/cm・sec・ at room temperature
The HgO sintered body according to claim 1, which has a temperature of at least .degree. (8) The hydration resistance of M
Weight increase due to gO becoming Mg(OH)_2 is 0
．． MgO according to claim 1, which is 0.02% or less
Sintered body. (9) The MgO sintered body according to claim 1, which has a dielectric constant of 10 or less at 100 kHz at room temperature. (10) The purity of MgO is 98% by weight as a chemical analysis value.
% or more, and a specific surface area of 10 m^2/g or more, is sufficiently mixed in an organic solvent and then molded and fired to form 2MgO・SiO_2 between fine MgO crystal particles.
It consists of a structure in which phases are evenly distributed and has a thermal conductivity of 0.08 cal/cm・sec・℃ or more in a greenhouse, 1
Dielectric loss (tanδ) at 00kHz is 1×10^
More than -^4 and less than 3 x 10^-^4, electrical insulation resistance is 3
A method for producing an MgO sintered body for an electrically insulating base material, characterized in that the MgO sintered body has a resistance of 10^1^0 Ω·cm or more at 00°C and has excellent hydration resistance. (11) The manufacturing method according to claim 10, wherein MgO powder having a specific surface area of 20 m^2/g or more is used. (12) SiO_ in which organic silicate remains in the sintered body
12. The method according to claim 10, wherein the two groups are fused in an organic solvent in an amount of 0.5 to 5% by weight. (13) The production method according to claim 10, wherein a silicate alcoholade is used as the organic silicate. (14) The production method according to claim 13, wherein ethyl silicate is used as the silicate alcoholade. (15) The manufacturing method according to claim 10 or 14, wherein the organic solvent is alcohol. (18) The production method according to claim 1, wherein the alcohol is ethanol. (17) The manufacturing method according to any one of claims 10 to 16, wherein the firing temperature is 1500°C or less. (18) The manufacturing method according to claim 17, wherein the firing temperature is 1450°C or less.