JPS6158405B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention particularly relates to a negative expansion powder material and an improved low expansion sealing composition containing the same.
Relates to products used for sealing IC packages, etc. Conventional sealing compositions based on solder glass are used for sealing, adhering, or coating preformed articles, glass appliances, metal bodies, ceramic materials, or members of semiconductor elements and semiconductor devices. The properties required of the sealing composition for this purpose are low expansion, high insulation, and the ability to form a strong seal by low-temperature and short-time fusion, as well as appropriate fluidity. For example, sealing glass used for sealing IC packages, display tubes, and furnace seals for cathode ray tubes seals a low expansion metal such as Kovar as a metal member and a ceramic substrate whose main component is A ₂ O ₃ . Therefore, it is necessary to have a coefficient of linear thermal expansion smaller than that of A ₂ O ₃ and larger than that of Kovar, a transition point of 400°C or less, and good electrical insulation properties. It was hot.
However, all the low melting point glasses conventionally used for this purpose have a drawback of having a large coefficient of linear thermal expansion. To eliminate this drawback, e.g. Li ₂ O-A
Attempts have been made to use _{2O3 - SiO2-} based or PbO- _B2O3 - _{TiO2 -} based crystalline glass to precipitate lead titanate or β-eucryptite crystals during heat treatment. However, in the former case, the insulation of the sealed portion is reduced due to Li ions, and the performance of the covered or sealed semiconductor element is also deteriorated due to the diffusion of the Li ions. On the other hand, the latter type of glass has the disadvantage that its sealing temperature is high and requires a relatively long sealing process. As another _means , _{zircon , quartz ,} or
Alternatively, the addition of a low expansion filler such as β-eucryptite is disclosed in US Pat. Nos. 3,250,631 and 3,258,350. Zircon, one example, has good acid resistance, but its linear thermal expansion coefficient is approximately 45×10 ^-7 /°C, so it is necessary to increase the amount added to lower the linear thermal expansion coefficient to the required value. The problem was that the melting temperature was high. As an example of a filler other than the above, lead titanate exhibits a negative linear thermal expansion coefficient of -60×10 ^-7 /℃, and although it improves the fluidity of glass, it has the disadvantage of a high dielectric constant. . β-Eucryptite, which is another example, has the smallest linear thermal expansion coefficient of -120×10 ^-7 /°C, and therefore has the effect of reducing the linear thermal expansion coefficient with a small amount added, and also has a low dielectric constant. Although it is low, when added to glass, it dissolves into the glass, impairs the fluidity of the glass, and is included in β-eucryptite.
There was a problem that Li ₂ O impairs the electrical insulation properties of the glass. The present invention aims to eliminate the various drawbacks of the prior art as described above, and provides a new negative expansion powder material (filler) and a new sealing composition using this filler. That is, the negative expansion powder material according to the present invention is characterized by having a surface coating of titanium oxide and/or zirconium oxide with a thickness of 1 micron or less on the surface of the β-eucryptite powder. moreover,
The low-expansion sealing composition according to the present invention contains 30% by weight or less of the above-mentioned negative-expansion material powder, and the remainder is essentially low-melting glass. A low-expansion sealing composition or composite material can also be obtained by using a known synthetic resin instead of this low-melting glass. The negative expansion powder material according to the present invention is a β-eucryptite crystal powder obtained by a known method, which has an appropriate particle size depending on the purpose, and is mixed with TiO ₂ and/or
It is obtained by forming a ZrO ₂ coating to a thickness of 1 μm or less, preferably 0.2 to 0.8 μm. The preferred particle size of the β-eucryptite crystal powder is approximately 5 to 25μ when used as a filler for low-expansion sealing glass, but it is approximately the same when used as a filler for synthetic resin sealants, and for other uses. can be selected as appropriate. Formation of TiO ₂ and/or ZrO ₂ coating is performed using Ti or
It can be obtained by decomposing an organic compound of Zr on β-eucryptite powder particles. The TiO ₂ film is formed using, for example, isopropyl orthotitanate or titanium isopropoxide as the organic compound of Ti, and in the case of the former, it is hydrolyzed under water vapor and brought into contact with β-eucryptite powder, and then about 600 It is formed by heat treatment at ℃. The present invention may include other known titanium organic compounds such as acylates or chelates, and the coating may be formed by thermal decomposition, reaction, or other methods.
CVD, chemical plating, etc. can also be used. As a Zr organic compound for forming _ZrO2 film,
A ZrO ₂ film can be obtained by contacting β-eucryptite powder particles with Zrn propoxide while hydrolyzing it with water vapor, and heat-treating it at about 600° C. after deposition. Other organic zirconates may include acylates and chelates. The TiO ₂ or ZrO ₂ coatings formed as described above are usually formed individually, but they may be formed in layers or in a mixture. β-eucryptite powder with a TiO ₂ and/or ZrO ₂ film formed on the surface with a thickness of 1μ or less is β-eucryptite powder.
- Has an expansion coefficient close to the negative expansion coefficient of eucryptite, and 30% by weight of this powder is applied to low melting point sealing glass.
When mixed below, the expansion coefficient of the glass is significantly lowered. The TiO ₂ or ZrO ₂ film is stable in the glass, effectively prevents the diffusion of Li in β-eucryptite into the sealing glass, and functions as an isolation film. Therefore, the insulation resistance of the sealing composition is maintained high, and in particular, in a bias test, it exhibits a value that is four orders of magnitude higher than that of a composition using uncoated β-eucryptite. Note that the TiO ₂ film is composed of PbO in PbO−B ₂ O ₃ glass.
A trace amount that does not increase the dielectric constant by reacting with
It is assumed that PbTiO ₃ is produced, which also gives a good constant contribution to thermal expansion and fluidity. However, from the viewpoint of fluidity, the thickness of the coating is preferably about 0.8μ or less, and from the viewpoint of insulation, the thickness is preferably 0.4 to 0.8μ. The present invention provides the above-mentioned TiO ₂ and/or ZrO ₂ coating β
- Among the known low melting point sealing glasses mixed with eucryptite powder material, PbO and
A total amount of B ₂ O ₃ of 70% by weight or more can be used. In addition, the known sealing glass described in Japanese Patent Publication No. 49-4525 can also be used as long as it meets the following conditions. That is, in the present invention, it is suitable to use glass whose linear expansion coefficient is in the range of 80 to 130×10 ^-7 /°C ^-1 between 30 and 250°C, and such glass has a linear expansion coefficient of about 250 Low melting point glasses with transition points at ~400°C are known. A suitable example of the PbO glass is PbO75
~82, _B2O3 6.5~ ₁₂ , ZnO7~14, _SiO2 1.5~3.0,
A ₂ O ₃ 0 to 3 (% by weight). The present invention further provides a novel low-expansion material and a sealing composition by blending the negative-expansion powder material of the present invention with a known synthetic resin. Resins used for plastic packages include bisphenol epoxy resins and silicone resins, and the effects of fillers added to these resins include improved mold release, heat resistance, moldability, and material cost savings. (because resin materials are expensive), etc. The amount of filler added is generally within 50 wt%. Preferred embodiments of the present invention are described below. Example 1 Each raw material of Li ₂ CO ₃ , A ₂ O ₃ and SiO ₂ was converted into Li ₂ O:A
₂ O ₃ :SiO ₂ was mixed in a molecular ratio of 1:1:2, kept in an alumina crucible at a temperature of 1400℃ for 3 hours, melted, then cooled and fritted to 900℃.
Heat treatment was performed again at a temperature of 5 hours to crystallize β-
A eucryptite crystallized product was produced. This was ground in a ball mill to obtain β-eucryptite powder with an average particle size of about 10μ. Next, isopropyl orthotitanate was mixed and stirred in steam with the β-eucryptite powder to cause hydrolysis, and titanic acid was deposited on the β-eucryptite surface.
Thereafter, it was heat treated at 600°C for 1 hour to form a TiO ₂ film. Its thickness is as shown in Table 1. next,
TiO ₂ coated powder PbO78, B ₂ O ₃ 16, A ₂ O ₃ 3,
20% by weight in a low melting point glass (Tg=305℃, α=113× ^10-7 /℃ ^-1 ) with a composition of SiO ₂ 3 (wt%)
The mixture was mixed and heated until it became fluid, and after cooling, various properties were measured, and the results are shown in Table 1. However, when the TiO ₂ film was particularly thin, isopropyl orthotitanate was heated to 80° C., vaporized or atomized using N ₂ gas as a carrier, and brought into contact with the β-eucryptite powder while being mixed with water vapor. Example 2 Zr.n.propoxide was mixed and stirred in steam with β-eucryptite powder (particle size approximately 10μ) obtained in the same manner as in Example 1, and hydrolyzed, followed by heat treatment at 600°C for 1 hour. to form a ZrO ₂ film. This ZrO ₂ coated powder was mixed in an amount of 20% by weight with the same glass as in Example 1, heated until it became fluid, and after cooling, various properties were measured and the results are shown in Table 2.

【table】

【table】

[Table] As detailed above, the negative expansion powder material of the present invention can be used as a low expansion sealing composition (or sealant).
Extremely useful for molding or sealing IC packages. That is, when used in an IC package,
The compatibility with Kovar, the ceramic part, and the silicon element is improved, and by suppressing the diffusion of Li ions in β-eucryptite into the glass, the insulation resistance between the leads does not deteriorate under bias, for the same reason. This also improves the fluidity of the glass. For this reason,
The present invention makes it possible to utilize β-eucryptite, which was previously difficult to put into practical use, as a negative expansion filler.
Since this filler has a lower dielectric constant than, for example, PbTiO ₃ , it has become possible to lower the dielectric constant of the entire sealing composition.

Claims (1)

[Scope of Claims] 1. A negative expansion powder material characterized by having a surface coating of titanium oxide and/or zirconium oxide with a thickness of 1 micron or less on the surface of β-eucryptite powder. 2 Contains up to 30% by weight of a negative expansion powder material having a surface coating of titanium oxide and/or zirconium oxide with a thickness of 1 micron or less, and the balance is 30 to 30% by weight.
1. A low-expansion sealing composition essentially consisting of a low-melting glass having a linear expansion coefficient of 80 to 130×10 ^-7 °C ^-1 between 250 °C and 250 °C. 3. The low expansion sealing composition according to claim 2, wherein the low melting point glass has a transition point of 250 to 400°C. 4 The low melting point glass has a total amount of PbO and B ₂ O ₃
3. The low expansion sealing composition according to claim 2, which is glass containing 70% by weight or more. 5 β- having a surface coating of titanium oxide and/or zirconium oxide with a thickness of 1 micron or less
1. A low expansion sealing composition comprising 50% by weight or less of eucryptite, with the remainder essentially consisting of a bisphenol epoxy resin or a silicone resin.