JPH05238774A - Glass composition for low temperature sintered base plate and base plate obtained therefrom - Google Patents

Abstract

PURPOSE:To obtain a glass composition for a low temp. sintered base plate low in the coefficient of thermal expansion, dielectric constant and excellent in strength, etc., by constituting this composition with a glass having a specific composition depositing the double crystal phase of mullite and cordierite by a heat treating. CONSTITUTION:The glass having the composition of, by weight, 20-35% SiO2, 35-45% Al2O3, 5-15% B2O3, 8-20% MgO, 0-4% CaO, 0-4% BaO, 0-4% CaO+BaO, 0.5-5% ZnO, 0-2% Li2O, 0-2% NA2O, 0-2% K2O, 1-4% Li2O+Na2O+K2O, 0-3% ZrO2, 0-3% SnO2, 0.1-4% ZrO2+SnO2 and the double crystal phase depositing mainly mullite and cordierite by heat treating is prepared. The glass having preferably <=45X10<-7>/ deg.C and >=1800kg/cm<2> deflective strength is molded, sintered to produce the low temp. sintered base plate.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention can be easily produced and has excellent mechanical strength, electrical insulation, low thermal expansion coefficient and low dielectric constant by precipitating mullite and cordierite as main crystal phases after heat treatment of glass. And the like, and mainly relates to a glass composition for a low-temperature fired multilayer substrate which is most suitable for packaging and assembly of semiconductor elements.

[0002]

2. Description of the Related Art Conventionally, Al ₂ O ₃ (alumina) has been generally used as a substrate material for computers, consumer appliances, etc. With higher integration, higher speed, and higher packing density of semiconductor elements, a substrate material that replaces alumina has been required.

Therefore, glass, crystallized glass, a mixture of glass or crystallized glass and a refractory filler, which has a lower coefficient of thermal expansion and a lower dielectric constant than alumina and can be fired at a low temperature, such as Ag / Pd, Cu. Although various substrate materials that can use conductors such as Au and Au have been proposed and partially put into practical use, they do not satisfy all the required characteristics, and mechanical strength is a major issue that is less than that of alumina substrates. There is.

A mullite or cordierite-based crystallization that satisfies the above-mentioned required characteristics of the substrate material, that is, that it can be fired at a low temperature of about 1000 ° C. or less, low thermal expansion coefficient, low dielectric constant, high strength and high insulation resistance. There is glass. However, the conventional manufacturing of mullite or cordierite-based glass requires a high temperature of 1600 ° C. or higher, so that there is a drawback that the erosion of the furnace material and the consumption of electrodes and the like used during electric melting are severe. Further, when there is not much difference between the liquidus temperature and the molding temperature, there is a problem that crystallization progresses so quickly that molding becomes impossible, which is not suitable for continuous production or mass production.

In addition, generally known fluxes for lowering the melting temperature, such as R ₂ O (R is an alkali metal),
When B ₂ O ₃ or the like is added, the crystallization of the glass after heat treatment is suppressed, the mechanical strength is lowered, and the coefficient of thermal expansion is increased, and the advantages of mullite and cordierite crystals are high strength and low coefficient of thermal expansion. The phenomenon that it becomes impossible to keep etc. has occurred.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a glass composition for a low temperature baking substrate, which has been developed based on the above problems. That is, in weight percent on _{oxide: SiO 2: 20~35% Al 2} O 3: 35~45% B 2 O 3: 5~15% MgO: 8~20% CaO: 0~ 4% BaO: 0 2-4% However CaO + BaO: 0~ 4% ZnO : 0.5~5% Li 2 O: 0~ 2% Na 2 O: 0~ 2% K 2 O: 0~ 2% where _{Li 2 O + Na 2 O +} K 2 O : 1-4% (at least two _{essential) ZrO 2: 0~ 3% SnO} 2: 0~ 3% However ZrO ₂ + SnO _2: consists from 0.1 to 4%, mullite and co by heat treatment - cordierite as a main It is a glass composition that precipitates the above double crystal phase. In addition, it can be sufficiently melted at a temperature of 1530 ° C or lower, and the crystallinity of mullite and cordierite is sufficiently high, and the coefficient of thermal expansion is 45 × 10 ^-7 / ° C or lower and the bending strength is 1800 Kg / cm. It is characterized in that it is ² or more.

The present invention also uses the above glass composition,
Regarding a substrate manufactured by firing at a low temperature of about 1000 ° C. or less,
Physical properties such as low coefficient of thermal expansion, low dielectric constant, high strength, and high insulation resistance can be obtained.

The glass in the present invention is composed of B ₂ O ₃ , Mg
1530 by adding O, ZnO, R ₂ O (R = Li, Na, K, at least two essential) as essential components.
It became possible to melt sufficiently at a temperature of ℃ or less and to have characteristics suitable as a material for low temperature firing substrates.

By adding MgO to the glass, a new cordierite crystal ( ₂ Al ₂ O ₃ .2SiO ₂ ) is hardly added, while the crystallinity of the mullite crystal (3Al ₂ O ₃ .2SiO ₂ ) itself is not lowered.
MgO.2Al ₂ O ₃ .5SiO ₂ ) precipitates. Co-
Jellite crystals have lower thermal expansion coefficient and dielectric constant than mullite and physical properties similar to mullite in bending strength, and are suitable as materials for low-temperature fired substrates. Therefore, addition of MgO not only lowers the melting temperature but also increases the crystallinity of the total, which contributes to the improvement of strength and also has the function of lowering the thermal expansion coefficient and the dielectric constant.

Further, by adding the R ₂ O (R = Li, Na, K, at least two essential components) component, the electric conductivity of the glass at high temperature becomes large, so that electric melting can be applied, and -It is now possible to melt the glass in a stable state. When the R ₂ O component is used alone, it lowers the insulation resistance of the crystallized glass after heat treatment, but when two or more components are added at the same time and the mixed alkali effect is used, the reduction of the insulation resistance can be suppressed. Addition of three or more components of alkali metal oxides makes the effect more remarkable.

As the crystallization accelerator, SnO ₂ and ZrO are used.
It turns out that ₂ is the most effective. Generally, the crystallinity does not increase so much in the composition region where the vitrification region is wide and the melting is easy, but by adding the above-mentioned crystallization accelerator to the glass, even in the composition region where the melting is easy, the low temperature firing substrate can be used. A glass with sufficient crystallinity having sufficient characteristics was obtained.

However, TiO, which is one of the crystallization accelerators,
With _2, it was found that not available to appear is produced when black spots low temperature fired substrate. Further, although P ₂ O ₅ has a slight effect as a crystallization accelerator by lowering the melting temperature by adding P ₂ O _5, it cannot be used because a void appears during the production of a low temperature fired substrate.

The reasons for limiting the oxide of the present invention are as follows.

SiO ₂ is a glass-forming oxide, and the main precipitated crystal phase is mullite (3Al ₂ O ₃ .2Si).
O ₂ ) and cordierite (2MgO ・ 2Al ₂ O ₃・ 5)
Since it is a constituent component of SiO ₂ ), if it is less than 20 wt%, it becomes difficult for these crystals to precipitate. Conversely, 35 wt%
If it exceeds, the crystallinity does not increase because it enters a stable vitrification region.

Al ₂ O ₃ is a glass intermediate oxide and is a constituent component of mullite and cordierite, which are main precipitated crystal phases. When Al ₂ O ₃ is less than 35 wt%, the crystallinity is less than 50 vol%, and the bending strength is 1800 Kg /
Does not reach cm ² . On the other hand, if it exceeds 45 wt%, the melting temperature becomes high and devitrification is likely to occur. B ₂ O ₃ is used as a flux, and if it is less than 5 wt%, the melting temperature becomes too high. On the other hand, if it exceeds 15 wt%, the crystallinity is lowered, which is not preferable.

R'O (R '= Ca, Ba) is a glass-modified oxide. When R'O is added, it has the function of preventing devitrification of the glass and widening the vitrification region and lowering the melting temperature, but on the other hand, the crystallinity decreases as it is added. Therefore, if added in excess of 4 wt%, the coefficient of thermal expansion will be 45 x 1
It becomes higher than 0 ^-7 / ° C, and the matching property with the silicon chip (coefficient of thermal expansion = 30 × 10 ^-7 / ° C) mounted on the low temperature fired substrate is lowered, and the strength is also lowered.

MgO is a constituent component of cordierite crystals, and if it is less than 8 wt%, the amount of precipitated cordierite crystals is small and the crystallinity as total cannot be improved. On the other hand, if it exceeds 20 wt%, it enters the phase separation region and devitrifies during melting.

[0018] ZnO is used as same flux as B ₂ O _3, the B ₂ O ₃ can reduce volatilization easily the amount of B ₂ O ₃ in molten by replacing ZnO. It also has the function of improving the chemical durability of the glass itself. If ZnO is less than 0.5 wt%, it has no effect. On the contrary, if it exceeds 5 wt%, it enters a stable vitrification region, the crystallinity of mullite and cordierite does not rise, and spinel-type crystals appear. And the coefficient of thermal expansion is 45 ×
It cannot be kept below 10 ^-7 / ° C.

R ₂ O (R = Li, Na, K) is used as a fluxing agent and as a carrier for enhancing electric conductivity during electric melting. In order to keep the insulation resistance of the low temperature fired substrate as high as possible, it is necessary to use not only one component but two or more components at the same time. R ₂ O is 1w in total
If it is less than t%, there is no effect as a carrier during electric melting. On the contrary, either Li ₂ O, Na ₂ O, or K ₂ O is 2w
If it exceeds t% or if the total exceeds 4% by weight, not only the insulation resistance as a low temperature fired substrate lowers but also the thermal expansion coefficient becomes too large. R ₂ O is 1 to 1 for the above reason.
Although it is 4 wt%, the composition ratio of at least two kinds is 0.
It is preferably 3 wt% or more. When R ₂ O is used as the two components, any combination of two kinds may be used, but a combination of Li ₂ O and K ₂ O in which the mixed alkali effect is most remarkable is more preferable. The effect is more remarkable when three components of R ₂ O are added.

ZrO ₂ and SnO ₂ are used as crystallization accelerators. The total amount of ZrO ₂ and SnO ₂ is 0.1 wt
% Is less effective, one of them is 3 wt.
%, Or more than 4 wt% in total, 15
It cannot be completely melted at a temperature of 30 ° C. or lower, and unmelted residue is left at the bottom of the crucible or kiln. Further, in addition to the function as a crystallization accelerator, F ₂ having a function as a flux is SnO ₂ , ZrO.
May be used in combination with ₂ .

[0021]

By using the glass composition of the present invention, a low temperature fired substrate mainly having a double crystal phase of mullite and cordierite can be obtained. That is, B
₂ O ₃ , MgO, ZnO, R ₂ O (R = Li, Na,
By adding a fluxing agent such as K) and a crystallization accelerator such as ZrO ₂ , SnO ₂ or the like, it can be easily melted at a temperature of 1530 ° C. or lower and can be fired at a low temperature of about 1000 ° C. or lower. It is possible to obtain a low temperature fired substrate having characteristics such as a coefficient of thermal expansion of 45 × 10 ⁻⁷ / ° C. or less, a dielectric constant of 7 or less, a bending strength of 1800 Kg / cm ² or more, and an insulation resistance of 10 ¹⁴ Ω · cm or more.

[0022]

[Examples and Comparative Examples] According to a conventional method, each ingredient material is appropriately weighed and blended so as to obtain the target composition shown in the table to prepare a batch, which is melted at the melting temperature shown in the table for 2 to 3 hours and melted. Use glass. This molten glass is molded into flakes with a water-cooled roll. Finely crush this glass with a ball mill,
The glass fine powder has an average particle size of about 2 to 5 μm.

In the case of producing a substrate, an organic binder, a solvent and the like were added to the substrate to make a slurry, which was then molded into a green sheet by the doctor blade method. After cutting and stacking this, 850 to 850 at a heating rate of 200 ° C / h in the atmosphere.
The temperature was raised to 1000 ° C., the firing temperature was maintained for 2 hours to obtain a low temperature firing substrate, and the dielectric constant and insulation resistance were measured by the following methods. The results are shown in Table 1 (Examples) and Table 2 (Comparative Examples).

The differential thermal analysis (DTA), coefficient of thermal expansion, crystal phase, crystallinity, and bending strength were measured by the following methods using the glass fine powders obtained in this example and comparative examples. did. The results are shown in Table 1 (Examples) and Table 2.
(Comparative example).

Dielectric Constant Each glass powder was molded on a substrate as described above, and an electrode was applied to the substrate and impeded at 25 ° C.-60% RH and 1 MHz.
Measured with a dance meter. This value is required to be 7 or less.

Insulation Resistance Each glass powder was molded on a substrate as described above, an electrode was applied to the glass powder, and the resistance was measured by an insulation resistance meter at 25 ° C.-60% RH and 500V. This value is required to be 10 ¹⁴ Ω · cm or more.

Differential thermal analysis (DTA) 500 mg of each glass powder was put into a sample holder of a differential thermal analyzer, and the temperature was raised from room temperature at a temperature rising rate of 20 ° C./min to obtain a transition point, a softening point and a crystallization peak. The temperature was measured.

Coefficient of thermal expansion Each glass powder was pressed into a rod shape with a pelleter, and then D
The thermal expansion coefficient (average value of 30 to 400 ° C., unit: 10 ⁻⁷ / of the sample which was heated at 200 ° C./h to the crystallization peak temperature measured by TA and held at that temperature for 2 hours and sintered ℃)
Was measured.

Crystal Phase The same material as the sample obtained as described above was made into fine powder again and then measured by powder X-ray diffraction.

Crystallinity The peak intensity of powder X-ray diffraction was measured (5 to 5% of the main peak).
10 pieces) and calculated based on a calibration curve prepared in advance (vol%). This has a close relationship with the bending strength of the low temperature fired substrate, and unless the crystallinity is 50 vol% or more, a bending strength of 1800 kg / cm ² or more cannot be obtained.

Bending strength JIS-R16 is the same as the sample obtained above.
The sample was processed according to No. 01, and its strength was measured by three-point bending. This value is required to be 1800 Kg / cm ² or more.

[0032]

[Table 1]

[0033]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Kuribayashi Yamamura Glass Co., Ltd. 2-21 Hamamatsubara-cho, Nishinomiya-shi, Hyogo (72) Inventor Jun Tanaka 1-1-1 Yamashita-cho, Kokubun-shi, Kagoshima Kyocera Stock Company Kagoshima Kokubun Plant (72) Inventor Yoshihiro Morikami 1-1, Yamashita-cho, Kokubun City, Kagoshima Prefecture Kyocera Stock Company Kagoshima Kokubun Plant

Claims (3)

[Claims] 1. A glass in which a double crystal phase of mullite and cordierite is mainly deposited by heat treatment, and is expressed in weight% of oxide: SiO ₂ : 20 to 35% Al ₂ O ₃ : 35 to 45. _{% B 2 O 3: 5~15%} MgO: 8~20% CaO: 0~ 4% BaO: 0~ 4% provided that CaO + BaO: 0~ 4% ZnO : 0.5~5% Li 2 O: 0~ 2 % Na ₂ O: 0 to 2% K ₂ O: 0 to 2% However, Li ₂ O + Na ₂ O + K ₂ O: 1 to 4% (at least two kinds are essential) ZrO ₂ : 0 to 3% SnO ₂ : 0 to 3% However, a glass composition for a low-temperature fired substrate, which comprises ZrO ₂ + SnO ₂ : 0.1 to 4%. 2. Melting is possible at a temperature below 1530 ° C.,
After heat treatment of glass, it mainly has a mullite and cordierite double crystal phase and has a thermal expansion coefficient of 45 × 10 ⁻⁷ / ° C. or less,
The glass composition for a low temperature fired substrate according to claim 1, which has a bending strength of 1800 Kg / cm ² or more. 3. A low temperature fired substrate produced by molding and firing the glass composition according to claim 1 and / or 2.