JPH0226864A - Ceramic composition sinterable at low temperature - Google Patents

Abstract

PURPOSE:To obtain a ceramic compsn. sinterable at a low temp., having a low coefft. of thermal expansion and enabling the production of a circuit using an Ag-rich Ag/Pd conductor by incorporating specified amts. of Al2O3, SiO2 and PbO powders. CONSTITUTION:A ceramic compsn. sinterable at a low temp. is obtd. by incorporating 45-60wt.% Al2O3 powder, 15-30wt.% SiO2 powder and 20-35wt.% PbO powder. When the compsn. is mixed with <=5wt.% powder of at least one among ZnO, CaO, MgO, SrO and CaF2, the crystallization of a sintered body takes place at a lower temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-temperature fired ceramic composition, and more particularly to a low-temperature fired ceramic composition suitable for use in a ceramic substrate used in a circuit of an electronic device.

[Conventional technique #I] With the miniaturization and higher performance of electronic devices in recent years, IC, L
There is also a trend towards higher integration of circuits such as SI, and multilayer circuits are being put into practical use as highly integrated circuits. This multilayer circuit consists of ceramic substrates, conductor materials such as Ag/Pd, W, and MO, resistive materials such as RuQt/glass, and capacitor materials such as PbO/5iOz/Bz.
It is obtained by providing multiple layers of glass materials such as O3-based materials. This multilayer circuit is manufactured by a thick film wiring method, a co-firing method, or a thin film wiring method. In the thick film wiring method, a paste-like conductive material or the like is sequentially screen printed on a sintered ceramic substrate and fired each time. Also,
In the co-firing method, first, the ceramic substrate material (green sheet) created by the doctor blade method is cut into predetermined dimensions, a paste-like conductive material, etc. is printed on it, and these are laminated, crimped, and co-fired. and manufacture it. Further, in the thin film wiring method, a conductive material is applied on a sintered ceramic substrate by vacuum deposition or sputtering, and a circuit pattern is formed thereon by photolithography. Of these methods, the most commonly used and most efficient is the co-firing method.

Incidentally, the recent development of circuits requires higher performance of ceramic substrates. One way to improve the performance of this ceramic substrate is to lower the firing temperature.

In other words, the conventional general ceramic substrate is Affi2.
03, in order to sinter it, it is necessary to sinter it at a high temperature of about 1600° C. and in a reducing atmosphere using a hydrogen furnace or the like. Therefore, for example, it is necessary to use a high melting point material such as W or MO which has high electric resistance and price as the conductive material fired at the same time in the above-mentioned simultaneous firing method, and multilayer circuits etc. have problems such as signal delay and high cost. It had

Three types of low-temperature fired ceramic compositions for multilayer circuits have been studied: a glass composite system in which a filler is added to glass, a crystallized glass system, and a non-glass system that does not use glass. As a glass composite type low temperature fired ceramic composition, for example, S i Of-Aiz 03-P
A circuit board composition comprising bO-based glass powder and alumina, zircon or cordierite ceramic powder (
JP-A No. 61-205658), low-temperature fired ceramics made of alumina and glass powder with a yield point of 700° C. or more (Japanese Patent Laid-Open No. 61-222957), and the like are known. In addition, as a crystallized glass-based low-temperature fired ceramic composition, for example, cordierite (2Mg0.2A
ffizO3.5SiOz) type materials are known. Examples of non-glass-based low-temperature fired ceramic compositions include aluminum oxide, lead oxide, boron oxide,
A multilayer ceramic substrate with a ceramic layer consisting of silicon dioxide, oxides of group II elements, and oxides of group II elements
17474), Ag2O3 and 5ioz and 8203
and one or more of Cab, SrO, BaO and ZnO.
Publication No.) etc. are known.

[Problems to be Solved by the Invention] However, the low-temperature fired ceramic compositions that have been studied so far are not fully satisfactory in terms of low-temperature firing and thermal expansion coefficient. Moreover, among the conventional low-temperature fired ceramic compositions, the glass composite system uses expensive glass and has a problem in terms of cost.

Furthermore, the Aq/Pd conductor used as the conductor material is
It is known that a composition with a high proportion of Ag has a small sheet resistance, so signal processing is fast, and the cost is low, which is excellent. However, Ag/Pd conductors with a high proportion of AQ have a low melting point. Therefore, it has been desired to develop a low-temperature firing ceramic composition that can be fired even when using this low melting point Aq/Pd conductor.

The present invention was made with attention to the above-mentioned problems, and it is possible to create a circuit using an AQ/PcJ conductor that can be fired at a low temperature, has a small coefficient of thermal expansion, and therefore has a high proportion of Ag. The purpose of the present invention is to provide a low-temperature fired ceramic composition that can be manufactured.

[Means for Solving the Problems] The low-temperature firing ceramic composition of the present invention contains A-mon 203 powder: 45 to 60% by weight (hereinafter referred to as %).

), 5iOz powder: 15-30% and pb○ powder = 2
It is characterized by consisting of 0 to 35%.

Furthermore, the low-temperature fired ceramic composition of the present invention contains the above-mentioned main components, ZnO powder, CaO powder, MqO powder, and SrO powder.
It can also be composed of 5% or less of at least one of powder and CaFz powder.

AffizO3 is used to increase thermal conductivity (T-) and bending strength after sintering. If it is less than 45%, these effects will be small, and if it exceeds 60%, the effect of low-temperature firing will be reduced and the density will be poor.

Furthermore, 5iOz produces silicate crystals after sintering and provides low thermal expansion. If it is less than 15%, it becomes difficult to sinter and the effect of low thermal expansion is small, and if it exceeds 30%, the thermal conductivity decreases and the coefficient of thermal expansion increases.

In general, PbO provides low thermal expansion at low temperatures.

If it is less than 20%, it will be difficult to sinter at low temperatures, and if it exceeds 35%, the adhesiveness with the conductor will deteriorate and conversely it will become difficult to sinter.

ZnO, Cab, MqOSSrO and CaF2 allow even lower firing temperatures. If at least one of these exceeds 5%, densification will actually become worse. A more preferable range is 1 to 3%.

These Aλ203 powder, 5iOz powder and PbO powder or ZnO powder, CaO powder, M
At least one of the qO powder, SrO powder, and CaFt powder may be used in a total amount of 100%, and may be prepared, mixed, and fired by a conventionally known method.

Incidentally, unavoidable impurities may be included to the extent that they do not affect the circuit.

Further, the raw material used may be either crystalline or amorphous.

[Function] The relationship between the coefficient of thermal expansion, the firing temperature, and the degree of crystallinity and the firing temperature in a sintered body obtained by sintering the low-temperature fired ceramic composition of the present invention consisting of AffitO3, 5ift and PbO is shown below. If you do this, it will look like Figure 1.

Also shown in the figure are X-ray diffraction patterns showing crystals and crystallinity when fired at 700°C, 875°C, and ioooo°C. In this three-component system, as shown in FIG. 1, it is found that as the firing temperature rises, there is partial eutectic melting and vitrification, resulting in densification. Furthermore, by firing at high temperature, some of the glass phase becomes PbARzsiz
It can be seen that it changes into an OA crystal and imparts low thermal expansion.

In addition, the above main components, ZnO powder, CaO powder, MgO
In the sintered body obtained by sintering the low-temperature fired ceramic composition of the present invention comprising 5% or less of at least one of powder, SrO powder and CaF2 powder, the PbA
J! Crystallization of zsizoa occurs at even lower temperatures.

[Example] Next, embodiments embodying the present invention will be described.

In this example, six low-temperature fired ceramic compositions having the compositions shown in Table 1 were prepared. Then, a multilayer circuit was manufactured using these low-temperature fired ceramic compositions by the above-mentioned co-firing method. The manufactured multilayer circuits are referred to as samples (1 to 20). Note that in each sample, the composition (%) of the low-temperature fired ceramic composition, the firing temperature (°C), and the ratio of conductor paste (AQ/Pd) were varied. Below, sample 9 will be explained as an example.

First, particle size 1. 0μm Al1tO3 powder 466Q, particle size 5μm S i Ot 1>) powder 204g, particle size 5μm
PBO powder 300Q having a particle size of 1 μm and 30 g of a 2nQ powder having a particle size of 1 μm were mixed to prepare a low-temperature fired ceramic composition.

Then, ethanol:n-butanol:5ec-butanol-1:1:
A mixed solvent 400Q of No. 1 and peptizer E503 (manufactured by Chukyo Yushi Co., Ltd.) 69 were added, and the mixture was mixed and ground in a ball mill for 70 hours. Next, 40 g of polyvinyl butyral (PVB) and dibutyl phthalate (DBP > 50 g) were added as a binder into this ball mill, and the mixture was further mixed for 40 hours, and then stirred and defoamed in a vacuum to achieve a viscosity of 5.000 to 5.000.
A slurry of 20.0OOcps was produced. Then, using this slurry, a thickness of 0.2 was obtained using the doctor blade method.
A plurality of green sheets of 5111111 were made and cut into 100 mm squares. Additionally, through holes were formed in these green sheets. And Ag/Pd=1
A commercially available conductive paste such as No. 0010 was printed on this green sheet by screen printing to form a circuit pattern. Six green sheets with this circuit pattern formed thereon were stacked and a pressure of 200 ko/C1 was applied to form a plate-shaped body with a thickness of about i and 2 mm. From this plate-shaped body 6
A 60 mm plate was cut out, heated at a rate of 100°C per hour, and held at 500°C for 2 hours.
B1DBP was removed to obtain a ceramic degreased body. This ceramic degreased body was heated in air at a rate of 300°C per hour, held at a firing temperature of 900°C for 1 hour, and cooled in a furnace. In this way, a multilayer circuit was obtained. This multilayer circuit is Sample 9 in Table 1.

Similarly, a total of 20 samples were manufactured. Note that Table 1 also shows the proportion of the conductive paste used and the firing temperature.

Then, the coefficient of thermal expansion, degree of crystallinity, and crystallization temperature of the ceramic substrate of each sample were measured.

The coefficient of thermal expansion is 20 to 500 for the ceramic substrate of each sample.
The coefficient of linear thermal expansion (07°C) between temperatures of 0°C was measured.

The degree of crystallinity is determined by crushing the ceramic substrate of each sample with a mortar and measuring it in the angle range of 2θ-10 to 700 using an X-ray diffraction device, and comparing the crystalline peak and non-crystalline peak after removing the background. It was determined as the ratio (%) of the crystalline peak to the total diffraction intensity of the crystalline peak.

These thermal expansion coefficients and crystallinity degrees are also shown in Table 1.

In addition, a plurality of low-temperature fired ceramic compositions with the same composition as Sample 2.9 were prepared, and the coefficient of thermal expansion was measured in the same manner as above when the firing temperature was varied from 700 to 1000°C, and the results are shown in Figure 2. .

The crystallization temperature ('C) was determined by heating a powder sample obtained by pulverizing the ceramic substrate of each sample with an agate mortar at a rate of 10°C per minute using a differential thermal analyzer (D-A), and measuring the exothermic peak. I asked for more. The results are also shown in Table 1. Further, a differential thermal diagram of the temperature of the ceramic substrate of sample 2.9.11.13.14 is shown in FIG.

(Left below) As can be seen from Table 1, the low temperature firing ceramic compositions of this example (Samples 1 to 5) have crystallization temperatures of 950 to 1
Since it is as low as 040°C, it can be fired at a low temperature of 900 to 950°C, and has a low coefficient of thermal expansion of 5.2 to 7°5X10-6/'C.

Also, from FIG. 2, an example containing ZnO (sample 9)
It can be seen that lower thermal expansion is imparted by firing at a lower temperature than in the example (sample F12) which does not contain anything other than a three-component system.

Further, from FIG. 3, it can be seen that the examples containing ZnO1Cab, SrO, or CaFt (sample 9.11.13.14) can be crystallized at a lower temperature than the examples (sample 2) that do not contain anything other than the three-component system.

Note that the sample to which Mgo was added is not shown.

As can be seen from FIG. 2, FIG. 3, and Table 1, the low-temperature fired ceramic compositions of this example (Samples 6 to 6)
20) has a lower crystallization temperature of 848°C to 993°C, so when fired at a low temperature of 900 to 950°C, the crystallinity is as high as 60% to 80% or more, which is more excellent.

It also has an even lower coefficient of thermal expansion of 4.5 to 6.5X10-6/'C.

Note that a slurry was prepared using a method different from that in the above example, and a ceramic substrate for a multilayer circuit was fired. First, 470g of AR203 powder, 2649g of 5if2 powder, 264g of PbO powder
9 and ZnO powder 109 were prepared to prepare a low-temperature fired ceramic composition. And in this ceramic composition,
500q of ethanol and 6g of peptizer E503 (manufactured by Chukyo Yushi Co., Ltd.) were added, mixed and ground in a ball mill for 70 hours, and then dried at 100°C to obtain a mixed powder with an average particle size of 1 μm. Then, this mixed powder was held at 650° C. for 2 hours to become amorphous, cooled, and ground with a mortar to an average particle size of 3 μm to obtain a ceramic calcined powder.

In this case, for 1000g of this calcined powder, deflocculant E5
03 (Chukyo Yushi) 6Q, PVB40a, DBP50
Add Q and further ethanol:n-butanol:5ec
- 40 g of a mixed solvent with a mixing ratio of butanol of 1:1:1 was added, and the mixture was heated in a ball mill for 40 hours, and then defoamed to obtain a slurry with a viscosity of 5.000 to 20°000 Cps. The rest was a ceramic substrate using the same manufacturing method as in the above example. This method also gave the same results and had the effects and effects of the low-temperature fired ceramic composition of the present invention.

Moreover, although the low-temperature fired ceramic compositions of the examples were formed into multilayer circuits by the simultaneous firing method, the present invention is not limited to this, and may be manufactured by other methods.

[Effect of the invention] In the low temperature fired ceramic composition of the present invention, Aλ203
It has a composition consisting of powder: 45 to 60% by weight, 3iQz powder: 15 to 30% by weight, and PbO powder = 20 to 3511%, or this main component and ZnO powder, CaO powder, MgO powder, SrO powder and Since it has a composition consisting of at least one type of CaF2 powder = 5% by weight or less, it can be fired at low temperatures and has a small coefficient of thermal expansion. Therefore, circuits for electronic devices can be manufactured using an Ag/Pd conductor with a high proportion of A9.

[Brief explanation of the drawing]

Figure 1 shows the original t11(7)A1zO3,5iOt,
A microcosm showing the relationship between the coefficient of thermal expansion and the firing temperature, and the relationship between the degree of crystallinity and the firing temperature in a sintered body obtained by sintering a low-temperature fired ceramic composition of a three-component system of Nibi PbO, and an X-ray diffraction pattern. be. FIG. 2 shows PbAλxsiz containing ZnO in the example. 8 is a miniature diagram showing the relationship between the firing temperature and the coefficient of thermal expansion of No. 8. FIG. 3 shows ZnO1CaO1SrO, C
It is a differential thermal diagram due to aFz content. Patent applicant Nippondenso Co., Ltd. Agent Patent attorney Hiroshi Okawa

Claims (2)

[Claims] (1) Al_2O_3 powder: 45-60% by weight, SiO
A low-temperature firing ceramic composition comprising _2 powder: 15 to 30% by weight and PbO powder: 20 to 35% by weight. (2) Al_2O_3 powder: 45-60% by weight, SiO
The main components are _2 powder: 15 to 30% by weight and PbO powder: 20 to 35% by weight, and at least one of ZnO powder, CaO powder, MgO powder, SrO powder and CaF_2 powder: 5% by weight or less. Characteristic low-temperature firing ceramic composition.