JP2003176168A - Thermal shock resistant alumina-zirconia burning tool and method of producing the same (high temperature burning) - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burning tool free from silica components, which is made of an alumina-zirconia, has excellent thermal shock resistance, exhibits durability to repeated heat cycles, and is suitable especially, for burning electronic components, and to provide the burning tool for the electronic components, which is obtained by forming a zirconia layer on the surface of the alumina- zirconia core excellent in thermal shock resistance and is prevented from reacting with alumina, and which is composed of silica free base materials and is optimally used for firing MLCC (multilayer ceramic capacitor). <P>SOLUTION: The alumina-zirconia burning tool is composed of coarse particles and fine particles. In the alumina-zirconia burning tool, particles of zirconia are finely dispersed in alumina-based substance for binding alumina coarse particles by cooling from an alumina-zirconia partially molten phase. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for alumina / zirconia firing which requires thermal shock resistance, and more particularly to a jig for firing setters, shelves, caskets and the like.
The present invention relates to a firing jig used for firing electronic parts such as dielectrics, multilayer capacitors, ceramic capacitors, varistors, and chip inductors, and fine ceramics.

[0002]

BACKGROUND OF THE INVENTION Setters, shelves, sheets as jigs for firing electronic components used in firing electronic components such as dielectrics, multilayer capacitors, thermistors, varistors, and chip inductors. There are materials etc. Conventionally, a jig for firing such as alumina or alumina / mullite has been used. However, alumina has a poor thermal shock resistance, and there is a problem that cracks easily occur in an environment in which thermal shock is repeatedly raised and lowered in the firing furnace and the jig is broken. In recent years, a jig for alumina-mullite firing in which mullite is added to alumina is often used for the purpose of improving thermal shock resistance. Recently, electronic parts have been remarkably miniaturized and have high performance. When such small and high-performance electronic parts are fired on an alumina / mullite base material, SiO2 decomposed from mullite material contaminates the electronic parts to be fired. ,
There are problems that characteristics are deteriorated and yield is reduced.

The present invention has been made to solve the above problems, and is made of alumina having excellent thermal shock resistance.
The zirconia-based firing jig can provide a firing jig that is durable against repeated thermal cycles and has no silica component particularly in the firing of electronic components. Further, by forming a zirconia layer on the alumina-zirconia firing jig surface excellent in thermal shock resistance of the present invention, it is possible to prevent the reaction with alumina, and consisting of a silica-free base material,
It is possible to provide a jig for firing electronic components, which is optimal for firing MLCCs (multilayer ceramic capacitors) and the like.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a jig for burning alumina / zirconia composed of coarse particles and fine particles,
A material for firing electronic parts, characterized in that zirconia particles are finely dispersed in the alumina that binds coarse-grained alumina through the eutectic by cooling from the partially molten phase of alumina / zirconia, and the thermal shock resistance is remarkably enhanced. Can be provided.

The present invention will be described in detail below. The raw material composition is 20-70 for coarse-grained alumina having an average particle size of 30-500 μm.
2% by weight of fine-grained alumina having an average particle size of 0.1 to 20 μm
0 to 70 wt% and 5 to 30 wt% of zirconia particles having an average particle diameter of 0.1 to 100 μm. A partially molten phase is formed by firing such a molded body at a temperature of 1710 ° C. or higher, and a eutectic structure is formed in the cooling process. Mainly, zirconia particles are finely dispersed in an alumina material that bonds coarse particles to each other. As a result, it is possible to provide a jig for firing electronic components, which has significantly improved thermal shock resistance. The particle sizes of the coarse particles and the fine particles may be one kind or a combination of one or more kinds. For example, the average particle size of coarse-grained alumina is 70 μm and 250 μm.
Can be combined in the range of 20 to 70 wt%. The same applies to fine-grained alumina. As a result, it is possible to suppress the occurrence of cracks due to rapid heating and quenching, and it is possible to provide a jig for firing electronic components, which has a long life against repeated heating and cooling that is applied during actual firing of electronic components.

In the present invention, by combining coarse particles and fine particles, appropriate pores are contained, thermal stress is relieved, and thermal shock resistance is improved. Further, by dispersing the zirconia particles in the alumina that bonds the coarse-grained alumina particles together, the thermal shock resistance and the toughness are improved due to the stress strain due to the difference in thermal expansion due to heating and cooling of the zirconia. The raw material composition of the present invention is preferably 20 to 70 wt% of coarse-grained alumina,
Fine alumina is 20 to 70 wt% and zirconia is 5 to 30 wt%. The average particle size of the zirconia particles is 0.1 to 100 μm, more preferably 0.1 to 30 μm.
Is. Generally, if the number of coarse particles is increased, the thermal shock resistance is improved, but the strength is lowered, which is not practical. Here, by adding fine-grained alumina, sintering and densification are promoted, and the strength is improved. It is considered that the thermal shock resistance is improved by further adding zirconia.

In the present invention, it is possible to obtain a property having both thermal shock resistance and strength by controlling the ratio of coarse-grained alumina to fine-grained alumina appropriately and by controlling the addition amount of zirconia.

The firing temperature of ordinary alumina / zirconia-based materials is 1500 to 1700 ° C., but as a result of extensive studies, the present invention achieves a remarkable improvement in thermal shock resistance by firing at a temperature of 1710 ° C. or higher. Came to. According to the equilibrium diagram of the alumina-zirconia system, 1710 ° C
From the above, it can be seen that the partially molten phase appears and exhibits a eutectic composition by cooling from a temperature above this. In the present invention, sintering at a temperature of 1710 ° C. or higher promotes sintering of coarse-grained and fine-grained alumina, and alumina, particularly fine-grained alumina and zirconia particles react with each other to form a partially molten phase. A structure in which zirconia is finely dispersed is obtained. By finely dispersing the zirconia particles, the stress strain is dispersed and the development of cracks is suppressed.

As described above, according to the present invention, the pores properly introduced by the combination of coarse-grained and fine-grained alumina relax the stress. Furthermore, in the region where sintering has progressed, zirconia is finely dispersed and stress is relieved, and a material for firing electronic parts having both properties of strength and thermal shock resistance can be provided. A schematic diagram is shown in FIG. 1 as an example of such a structure.

As zirconia particles, unstabilized Ca
Zirconia partially stabilized and stabilized with O, MgO, Y2O3 or the like can be used. Moreover, 0.1 to 5 wt% of CaO, BaO, and Sr are added to alumina / zirconia.
One or more kinds of O, MgO, CeO2 or Y2O3 can be added. Such additives promote sintering and also act as stabilizers for zirconia.

The present invention as described above provides a jig for firing electronic parts which can be manufactured by various manufacturing methods such as pressed products, extruded sheet products and cast products, is excellent in strength and thermal shock resistance and is durable. Can be provided.

Further, a jig for firing electronic parts can be provided by forming a coating layer of zirconia on the alumina / zirconia-based fired body of the present invention and comprising a silica-free base material. As a coating method of zirconia, various methods such as spray coating, thermal spraying, dip coating, and casting can be appropriately adopted.

That is, the invention of [Claim 1] is an alumina / zirconia firing jig comprising coarse particles and fine particles,
Thermal shock-resistant alumina characterized by finely dispersing zirconia particles in alumina that binds coarse-grained alumina by cooling from the alumina-zirconia partially molten phase
A zirconia firing jig.

In addition,

2. The invention according to claim 2, wherein alumina particles composed of coarse particles and fine particles and zirconia particles are mixed to form a molded article,
By calcining the molded body at a temperature of 1710 ° C. or higher to form an alumina / zirconia partially molten phase, and then cooling this to finely disperse the zirconia particles in the alumina that binds the coarse-grained alumina. A method for manufacturing a heat-shockable alumina / zirconia-based jig for firing.

In addition,

According to a third aspect of the invention, the raw material composition has an average particle size of 30 to 50.
0-μm coarse-grained alumina 20-70 wt%, 0.1-2
Fine alumina of 0 μm is 20 to 70 wt% and 0.1 to
The thermal shock-resistant alumina according to claim 1, characterized in that the zirconia particles having a size of 100 μm are composed of 5 to 30 wt%.
A zirconia firing jig.

In addition,

According to a fourth aspect of the invention, the raw material composition has an average particle size of 30 to 50.
0-μm coarse-grained alumina 20-70 wt%, 0.1-2
Fine alumina of 0 μm is 20 to 70 wt% and 0.1 to
The thermal shock-resistant alumina according to claim 2, characterized in that the zirconia particles having a size of 100 μm are composed of 5 to 30 wt%.
It is a method for manufacturing a zirconia firing jig.

That is, the invention of [Claim 5] uses, as the zirconia, zirconia that is not stabilized, partially stabilized and stabilized with CaO, MgO, Y2O3 or the like. This is a jig for impact alumina / zirconia firing.

In addition,

6. The invention according to claim 6, which is unstabilized as zirconia,
3. The method for manufacturing a heat shock resistant alumina-zirconia firing jig according to claim 2, wherein zirconia partially stabilized and stabilized with CaO, MgO, Y2O3 or the like is used.

In addition,

7. The invention according to claim 7 relates to an alumina / zirconia material having a grain size of 0.
5-5 wt% CaO, BaO, SrO, MgO or Y
The heat-shockable alumina / zirconia firing jig according to claim 1, wherein one or more kinds of 2O3 are added.

In addition,

8. The invention according to claim 8 is based on alumina / zirconia.
5-5 wt% CaO, BaO, SrO, MgO or Y
3. The method for manufacturing a heat shock-resistant alumina / zirconia firing jig according to claim 2, wherein one or more kinds of 2O3 are added.

In addition,

9. The heat shock-resistant alumina / zirconia firing jig according to claim 1, wherein a zirconia coating layer is formed on the surface of the alumina / zirconia firing jig. .

In addition,

10. The heat shock resistant alumina according to claim 2, wherein the zirconia coating layer is formed on the surface of the alumina / zirconia firing jig.
It is a method for manufacturing a zirconia firing jig.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An example of manufacturing a jig for firing an electronic component of the present invention will be described, but the example does not limit the present invention.

Example 1 As an alumina raw material, # 220 (average particle size: about 70 μm)
50% by weight of coarse-grained alumina and 45% by weight of fine-grained alumina powder having an average particle size of about 10 μm are used as zirconia #
5 wt% of CaO-stabilized zirconia powder having an average particle size of 350 (about 30 μm) was used. Using a high-speed mixer, these raw materials were stirred and mixed with several wt% of powder binders such as Metroze and dextrin, and further, several wt% of binders such as methylcellulose and glycerin and water were added and mixed with stirring. Then, using three rolls, the raw material powder is uniformly dispersed.
Mixed. These compounds were molded into a sheet having a thickness of 2 to 3 mm using an extrusion molding machine and dried. These sheets were cut into 10 to 20 cm squares and baked at 1740 ° C. for 10 hours.

Bending test pieces were cut out from the alumina / zirconia sheet produced in this manner, and a three-point bending test was performed as room temperature strength, and 3 after quenching as thermal shock resistance evaluation.
A point bending test was conducted. To evaluate the thermal shock resistance, a method of holding a test piece for 20 minutes in an electric furnace set to a predetermined temperature and quenching it in water is adopted, and the point at which the strength sharply decreases by a three-point bending test after quenching The difference was evaluated as ΔT (holding temperature-water temperature). An example of measuring ΔT is shown in FIG. The results are shown in Table 1.

[0027]

[Table 1]

Examples 2 to 8 In the same manner as in Example 1, Table 1 shows the average particle size and blending wt% of coarse-grained alumina and fine-grained alumina, the type of zirconia raw material, the average grain size, and the blending wt%. Select 11710
It was fired at a temperature of ℃ or higher, and the strength and thermal shock resistance were evaluated. The results are shown in Table 1.

Comparative Examples 1 to 5 In the same manner as in Example 1, Table 1 shows the average particle size and blending wt% of coarse-grained alumina and fine-grained alumina, the type of zirconia raw material, the average grain size, and the blending wt%. It was selected and fired at various temperatures to evaluate strength and thermal shock resistance. The results are shown in Table 2.

[0030]

[Table 2]

[0031]

From the above description, an alumina / zirconia firing jig having excellent thermal shock resistance can be used to obtain a firing jig which is durable against repeated thermal cycles and has no silica component particularly in the firing of electronic parts. Can be provided. Further, by forming a zirconia layer on the alumina-zirconia firing jig surface excellent in thermal shock resistance of the present invention,
It is possible to provide a jig for firing electronic parts, which is capable of preventing a reaction with alumina and which is made of a silica-free base material and is optimal for firing MLCC (multilayer ceramic capacitor) or the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a fine structure according to the present invention.

FIG. 2 shows an example of thermal shock resistance evaluation relating to the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhisa Izutsu             Mitsui Kinzoku, 3-1 Asamu-cho, Omuta-shi, Fukuoka             Mining Co., Ltd. Ceramics Division Technology Development             Department (72) Inventor Satoshi Horiuchi             Mitsui Kinzoku, 3-1 Asamu-cho, Omuta-shi, Fukuoka             Mining Co., Ltd. Ceramics Division Technology Development             Department F-term (reference) 4G030 AA07 AA08 AA09 AA12 AA17                       AA36 BA23 BA25 GA11 GA27

Claims (10)

[Claims] 1. A jig for firing an alumina / zirconia material comprising coarse particles and fine particles, wherein the zirconia particles are finely dispersed in the alumina material which binds the coarse particle alumina by cooling from the alumina / zirconia partially molten phase. A jig for thermal shock resistance alumina / zirconia firing characterized by 2. Alumina particles comprising coarse particles and fine particles and zirconia particles are mixed to form a compact, and the compact is fired at a temperature of 1710 ° C. or higher.
By forming a zirconia partially molten phase and then cooling it, zirconia particles are finely dispersed in the alumina that binds coarse-grained alumina. Production method. 3. A raw material composition is 20 to 70 wt% of coarse alumina having an average particle diameter of 30 to 500 μm, 20 to 70 wt% of fine alumina of 0.1 to 20 μm, and 0.1 to 100 μm.
The heat-shockable alumina / zirconia firing jig according to claim 1, characterized in that the zirconia particles in (5) are composed of 5 to 30 wt%. 4. A raw material composition is 20 to 70 wt% of coarse alumina having an average particle size of 30 to 500 μm, 20 to 70 wt% of fine alumina of 0.1 to 20 μm, and 0.1 to 100 μm.
The method for manufacturing a heat shock resistant alumina-zirconia firing jig according to claim 2, characterized in that the zirconia particles of 5 are comprised of 5 to 30 wt%. 5. As zirconia, unstabilized, CaO, M
The jig for thermal shock resistance alumina-zirconia firing according to claim 1, wherein zirconia partially stabilized and stabilized with gO, Y2O3 or the like is used. 6. As zirconia, unstabilized, CaO, M
The method for producing a heat shock resistant alumina-zirconia firing jig according to claim 2, wherein zirconia partially stabilized and stabilized with gO, Y2O3 or the like is used. 7. Alumina / zirconia material with 0.5 to 5 wt.
% CaO, BaO, SrO, MgO or Y2O3 1
The heat-shockable alumina / zirconia firing jig according to claim 1, wherein more than one kind is added. 8. Alumina / zirconia material 0.5 to 5 wt.
% CaO, BaO, SrO, MgO or Y2O3 1
3. The method for manufacturing a heat shock-resistant alumina / zirconia firing jig according to claim 2, wherein more than one kind is added. 9. The thermal shock resistant alumina / zirconia firing jig according to claim 1, wherein a zirconia coating layer is formed on the surface of the alumina / zirconia firing jig. 10. The method for manufacturing a heat shock resistant alumina / zirconia-based jig according to claim 2, wherein a zirconia-based coating layer is formed on the surface of the alumina / zirconia-based jig.