JPH0264059A - Low-temperature sintering ceramic composition for multilayer substrate - Google Patents

Abstract

PURPOSE:To obtain the title composition capable of sintering at a relatively low temperature, having small coefficient of thermal expansion and dielectric constant and high mechanical strength by adding GeO2 and/or TiO2 to a main ingredient consisting of cordierite, B2O3 and SiO2. CONSTITUTION:1-10wt.% GeO2 and/or TiO2 is added to a main ingredient consisting of 40-85wt.% cordierite, 10-40wt.% B2O3 and 5-50wt.% SiO2. Sintering of a ceramic can be carried out at relatively low temperature of <=1020 deg.C and the title composition having small coefficient of thermal expansion and dielectric constant and high mechanical strength by the above-mentioned blending. Thereby energy required to sintering is reduced and use of high-melting metal as a conductive material for forming circuit pattern is made unnecessary. Since a ceramic substrate having the aimed composition is small in coefficient of thermal expansion and has coefficient of thermal expansion close to that of silicon chip, crack occurrence by heat strain is extremely small even when the silicon chip is carried on the substrate porosity is decreased and high reliability is attained by further adding TiO2 and GeO2, since mechanical strength thereof is as high as that of alumina.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to a low-temperature sintered porcelain composition for a multilayer board, and particularly to a multilayer porcelain composition in which a plurality of porcelain layers are laminated and a circuit is formed between the porcelains. The present invention relates to a low-temperature sintered ceramic composition for multilayer substrates, which is suitable for substrates.

[Prior art] -e. With the miniaturization of electronic devices, ceramic substrates are widely used to mount various electronic components that make up electronic circuits, and recently, in order to further increase the packaging density, conductive materials are used on the surface. A multilayer porcelain board has been developed in which a plurality of unfired porcelain sheets on which circuit patterns are formed using paste are laminated and then fired and integrated. Conventionally, alumina has been used as a material for such multilayer ceramic substrates.

[Problem to be solved by the invention]

However, for alumina, ■ its sintering temperature is 1500 ~
Because the temperature is as high as 1,600°C, a large amount of energy is required for sintering, resulting in high costs. ■The conductive material of the internal circuit formed inside the substrate must be able to withstand the high sintering temperature, such as W or Mo. The circuit pattern itself has a high resistance value because it is limited to high melting point metals. ■The thermal expansion coefficient of alumina is larger than that of the silicon chip that makes up the semiconductor mounted on the alumina substrate, so the silicon chip does not receive heat. There were problems such as adding stress and causing cracks, and (2) the high dielectric constant of alumina itself, which increased the delay time of signals propagating inside the circuit.

Therefore, an object of the present invention is to provide a low-temperature sintered ceramic composition for a multilayer substrate that can be sintered at a relatively low temperature, has a small coefficient of thermal expansion, a small dielectric constant, and high mechanical strength.

[Means to solve the problem]

The low-temperature sintered ceramic composition for multilayer substrates of the present invention contains 40 to 85% by weight of cordierite and 10 to 40% by weight of Bz03.
It is characterized in that 1 to IO weight % of one or more of GeOt and TiO□ is added to the main component consisting of 5 to 50 weight % of SiO□ and SiO□ before external addition.

Here, cordierite is 2Mg0・2AhOi・5
In addition to SiO2, “Phase Diagrams for C” by E.N. Levin et al.
eramists”, The American
Ceramic 5ociety, Columbus,
1964. P, 246 (Fig, 712), and more specifically refers to the region in FIG.

Further, the composition range of the three main components mentioned above is shown in region B of FIG.

The reason for limiting the composition range as described above is as follows.

That is, if cordierite is less than 40% by weight, GeO□,
This is because even if T i O□ is added, the mechanical strength is still low, while if it exceeds 85% by weight, the sintering temperature becomes high.

Further, if the B2O3 content is less than 10% by weight, the sintering temperature will be high, while if it exceeds 40% by weight, the material will become porous and the mechanical strength will be low.

Further, if S i Oz is less than 5% by weight, the sintering temperature becomes high, while if it exceeds 50% by weight, the mechanical strength becomes low.

In addition, additives GeO□ and/or T i O
If Z is less than 1% by weight, the mechanical strength will be low;
If B20.% by weight is exceeded, the sintering temperature becomes high when the main component is a cordierite lynch group. This is because -3iO□ rich type has low mechanical strength and also has low specific resistance in both cases.

〔Example〕

First, raw materials for cordierite were prepared. As a raw material,
S i Ot , MgO or MgC0ff or T
alc(3Mg'0 ・4SiO2・HzO), Al
2O3 was weighed and mixed. Add this mixture to 1350-1
It was calcined at 400°C. In this way, the cordierite composition shown in FIG. 1 was obtained. This calcined cordierite was crushed and used as a new cordierite raw material.

Next, this cordierite raw material and other main constituent materials, namely B20. or BN or B, C and S
iO□ and additive constituent materials GeO□ and Ti12
to obtain porcelain with the composition shown in Table 1.
Weighed and mixed.

This mixture was then calcined at a temperature of 800 to 900°C and pulverized. An organic binder was added to the pulverized powder and kneaded, and the resulting slurry was formed into a sheet with a thickness of 1 mm using a doctor blade method. This ceramic green sheet was cut into a size of @130 mm and a width of 10 mm, and passed through water vapor in a nitrogen-steam reducing or non-oxidizing atmosphere using nitrogen as a carrier gas.
The binder component was burned at a temperature of .degree. C., and then fired for 1 hour at each temperature shown in Table 1 to obtain porcelain.

In addition, this ceramic green sheet is u3mm1 horizontal 4
Cut into 0mm square plates and stack them to 200k
It was pressurized at g/cni to form a prismatic shape of approximately 4 mm x 3 mm x 40 mm. Then, this was fired by the method described above and used as a measurement sample for measuring thermal expansion, bending strength, etc.

Table 1 shows the measurement results of each characteristic of each sample thus obtained.

The amounts of additives in the same table are based on the amount of external additives (wt.
), and more specifically, the amount of solid solution in cordierite and SiO□-B20. This is the sum of the amount added to the inside.

Further, the relative dielectric constant is a value measured at a frequency of IMHz.

The specific resistance is the value when a direct current of 100 cm is applied to the sample.

The coefficient of linear thermal expansion α is α=(ΔL/L (T2 T+))+αS i O2
Here, ΔL is the apparent elongation of the sample due to heating (mm), and L is the length of the sample at room temperature (mm).
), T, is room temperature, T2 is 500'C1αSiO□ is the coefficient of thermal expansion of quartz glass.

The bending strength is a value measured according to the three-point bending method of JIS standard (R1601).

The porosity is a value calculated from the density measured by the Archimedes method.

(Left below) In Table 1, those marked with an * are outside the scope of this invention, and all others are within the scope of this invention.

The reason for limiting the range is as follows.

That is, if cordierite is less than 40% by weight, G e O
Even if z, T i Oz is added, the mechanical strength is still low,
On the other hand, if it exceeds 85% by weight, the sintering temperature will be 1020°C or higher. Here, 1020°C is used as the standard because at lower temperatures, Ag, Ag
This is because Pd(80:20)%'Cu, etc. can be used.

Also, B20. is less than 10% by weight, the sintering temperature is 102
This is because if the temperature exceeds 0°C and the content exceeds 40% by weight, it becomes porous and the bending strength becomes less than 2500.

In addition, when SiO□ is less than 5% by weight, the sintering temperature is 1020
If the content exceeds 50% by weight, the bending strength becomes less than 2500.

Furthermore, if the additives GeO□ and/or TiOz are less than 1% by weight, the bending strength will be less than 2500, while if the content exceeds 10% by weight, the sintering temperature will be high in cordierite-rich systems, and B20 This is because the bending strength is low in the S i Oz rich system, and in both cases, the specific resistance is IQI2Ω·cm.

In the above examples, the firing atmosphere was set to a reducing or non-oxidizing atmosphere, but the properties shown in Table 1 can also be obtained even if firing is performed in an oxidizing atmosphere such as air. It was confirmed that

〔Effect of the invention〕

As described above, according to the low temperature sintered ceramic composition for multilayer substrates according to the present invention, the following effects can be obtained.

■ Since it can be sintered at a relatively low temperature of 1020°C or less, less energy is required for sintering, and there is no need to use high-resistance, high-melting-point metals as conductive materials to form circuit patterns. It's over.

For example, relatively inexpensive noble metals such as Ag and Ag-Pd can be used as the conductive material, and inexpensive base metals such as Cu and Ni can be used as they can be fired in either oxidizing or non-oxidizing atmospheres. You can also do it.

■ The coefficient of thermal expansion is about 3 x 10-h/'C, which is close to that of silicon (about 3.5 x IO-6/'C), so
Even if a silicon chip is mounted on this ceramic substrate, the incidence of cranks and the like due to thermal distortion is extremely small.

■ The relative dielectric constant is 4.9 or less, which is that of alumina (approximately 10)
Since it is smaller than , the signal propagation delay speed is small.

(2) The addition of GeO□ and TiO□ reduces the porosity of the fired body, and the mechanical strength is comparable to that of alumina, resulting in high reliability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the composition range of cordierite. FIG. 2 is a diagram showing the composition range of the main components of the composition according to the present invention. M9S Figure 1

Claims (1)

[Claims] (1) Cordierite is 40-85% by weight, B_2O_
310-40 wt% and 5-50 wt% SiO_2
For the main components consisting of GeO_2 and TiO_2
A low-temperature sintered ceramic composition for a multilayer substrate, characterized in that 1 to 10% by weight of one or more of the following is added as an external additive.