JP2002293649A - Method of manufacturing ceramic sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing ceramic sintered compact at a low sintering temperature with the adding quantity of a sintering aid powder or glass powder reduced to the utmost and nevertheless making the product dense. SOLUTION: After the surface of ceramic powder is treated with plasma, the molded and fired ceramic sintered compact is used as an insulating board 2 (wiring layers 2a and 2b) to form a wiring board 1 having a wiring layer 3 formed on the surface and/or the inside of insulating board 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic sintered body, and more particularly to an improvement in the sinterability of a ceramic sintered body using a non-oxide powder, particularly, a glass ceramic.

[0002]

2. Description of the Related Art Hitherto, a method of firing a ceramic sintered body at a low temperature has been studied. For this purpose, a method of adding a sintering aid has been generally adopted.
JP-A-290565 describes that ceramic powder can be vaporized by thermal plasma treatment to produce ultrafine particles, and the powder can be fired to produce a dense, dense, and high-strength ceramic sintered body. .

On the other hand, as a wiring substrate for a package for housing a semiconductor device, a glass powder and a ceramic powder are mixed and molded, and then fired at a temperature lower than the melting point of a low-resistance metal such as Cu or Ag and a metal of 1050 ° C. or less. So-called glass ceramics have been developed. Among them, AlN powder and S
Glass ceramics to which a non-oxide ceramic powder such as i ₃ N ₄ powder is added are being developed.

[0004]

However, in the above method of adding a sintering aid to the ceramic sintered body, it is necessary to increase the amount of the sintering aid for low-temperature firing. There is a possibility that the characteristics of the ceramic sintered body may be deteriorated by the auxiliary agent.
In the method using ultra-fine particles as disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, it is difficult to handle the powder, and sometimes agglomeration of the ceramic powder occurs and a dense sintered body cannot be obtained.

As the above-mentioned glass ceramics, it is desirable to increase the content of non-oxide ceramic powder in the glass ceramics from the viewpoint of higher thermal conductivity and higher strength. In order to densify the relative density of the glass ceramic to 95% or more at a temperature of 1050 ° C. or less, the non- The addition amount of the oxide ceramic powder was limited to about 30% by weight of the total amount.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to produce a ceramic sintered body and a glass ceramic which can be fired at a low temperature.

[0007]

Means for Solving the Problems The present inventor has studied the properties of ceramic powder with respect to the above-mentioned problems, and as a result, the surface of the ceramic powder has been subjected to plasma treatment to modify the surface of the ceramic powder. Improving the degree of sintering activation of the ceramic powder surface by removing impurity components present on the surface of the ceramic powder, changing the surface of the ceramic powder, and forming fine irregularities on the surface of the ceramic powder. As a result, it has been found that the firing temperature of the ceramic sintered body can be lowered.

That is, the method of manufacturing a ceramic sintered body according to the present invention is characterized in that the surface of a ceramic powder is subjected to plasma treatment, and then molded and fired.

Here, the plasma is air plasma or nitrogen plasma, and the plasma irradiation is performed in an oxidizing atmosphere; the plasma is irradiated at room temperature and normal pressure; Desirably, it is an oxide powder.

A thickness of 0.05 to 50 nm from the surface of the ceramic powder is modified by the plasma;
It is desirable that the attached amount of -OH groups attached to the surface of the ceramic powder after the plasma treatment is larger than the attached amount before the plasma treatment.

Further, the method for producing a glass ceramic according to the present invention is characterized in that a glass powder and the above-mentioned ceramic powder are mixed, molded and fired. % By weight and the ceramic powder in a proportion of 30 to 70% by weight, and the relative density of the glass ceramic is 95%.
It is desirable that this is the case.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a ceramic sintered body of the present invention comprises the steps of:
It is molded and fired. That is, by subjecting the surface of the ceramic powder to plasma treatment, (1) the effect of removing impurities such as dirt and oxide film adhered to the surface of the ceramic powder, and (2) the effect of removing the surface of the ceramic powder The degree of activation of the ceramic powder surface is caused by the effect of changing the molecular bonding state of the surface by the collision of the plasma particles, and (3) the effect of the plasma particles colliding with the surface of the ceramic powder to form minute irregularities on the surface of the ceramic powder. As a result, the firing temperature can be lowered when firing after molding the ceramic powder.

According to the present invention, not only the case where the above-mentioned plasma-treated ceramic powder is used alone, but also, for example, the mixing of the above-mentioned ceramic powder with a sintering aid powder, a glass powder or another ceramic powder. Also in powder, it is possible to improve the wettability between the plasma-treated ceramic powder and the above-mentioned other powder, to reduce the firing temperature and to reduce the amount of addition of the sintering aid powder or glass powder. It works.

The order of the plasma treatment may be such that after the ceramic powder is irradiated with plasma, other powders may be added and mixed, or conversely, the mixed powder may be irradiated with plasma.

Further, as a method of plasma-treating the ceramic powder, for example, a method of irradiating the ceramic powder with plasma while laying the ceramic powder on a base such as a belt conveyor, or a method of placing the ceramic powder in a stirrable container. And then irradiating the ceramic powder with plasma while stirring.

The step of irradiating the plasma can be performed after the ceramic powder has been molded. However, in this method, only the ceramic raw material powder on the surface of the molded body is irradiated with the plasma, and the surface of the ceramic powder is irradiated. Since no modification is performed, it is desirable to irradiate the ceramic powder before molding with plasma.

The ceramic (raw material) powder to be irradiated with plasma is, for example, spherical or spherical, having a purity of 90% or more.
It is desirably composed of fibrous, plate-like, irregular shapes and the like, and is particularly preferably spherical or irregular particles (powder) having an average particle size of 0.5 to 50 μm, particularly 0.8 to 10 μm.

Further, according to the present invention, only the surface of the ceramic powder, particularly 0.05 to 50 nm from the surface, particularly 0.1 to 0.5 nm.
In order to modify only the desired thickness of 1 to 10 nm, and to change the molecular bonding state on the surface of the ceramic powder to a more active state, an apparatus for plasma processing is inexpensive and plasma processing can be easily performed. In this respect, it is desirable to use atmospheric plasma or nitrogen plasma as the plasma, and furthermore, an apparatus for plasma processing is inexpensive, and the plasma processing can be easily performed. It is desirable that the plasma irradiation be performed.

Further, it is desirable to irradiate the plasma at room temperature and normal pressure, since plasma processing can be performed easily and inexpensively, and there is no need to use a special device such as a vacuum vessel.

Here, according to the present invention, only a desired thickness of 0.05 to 50 nm, particularly 1 to 10 nm from the surface of the ceramic powder can be modified by using the above-described plasma.

Further, according to the present invention, as the ceramic powder, an oxide powder or a non-oxide powder can be used. Especially effective.

Further, according to the present invention, by performing plasma processing using the above-described plasma,
-O adhering to the surface of ceramic powder after plasma treatment
It is desirable that the amount of the H group attached is larger than the amount before the plasma treatment, that is, it is desirable to increase the amount of the attached —OH group on the surface of the ceramic powder by irradiating the plasma as described above. In the case of mixing the treated ceramic powder and glass powder,
A dense ceramic sintered body (glass ceramic) can be produced at low temperature without causing a decomposition reaction such as foaming between the ceramic powder and the glass powder and increasing the wettability between the two.

As a method for producing the above-mentioned glass ceramic, for example, 30 to 70% by weight, particularly 35 to 60% by weight, further 45 to 55% by weight of the above glass powder is used.
And 30 to 70% by weight, especially 40% by weight of the ceramic powder.
Weighed and mixed at a ratio of 65 to 65% by weight, and further 45 to 55% by weight, and molded into a predetermined shape by a known molding method such as press molding, extrusion molding, cold isostatic pressing (CIP) molding, tape molding and the like. After that, in an oxidizing atmosphere or a non-oxidizing atmosphere, 1050 ° C. or less, particularly 800 to 10 ° C.
A method of firing at 00 ° C., more preferably at 850 to 950 ° C., is preferable.

According to the above method, a dense sintered body can be obtained by increasing the relative density of the glass ceramic to 95% or more, particularly 97% or more.

(Method of Manufacturing Wiring Board) Next, a method of manufacturing a wiring board having a wiring layer using the above-described ceramic sintered body as an insulating substrate will be described as an example. The above-mentioned plasma-treated ceramic powder is prepared, and mixed with the above-mentioned glass powder or a suitable sintering aid using a suitable organic solvent or solvent to prepare a slurry.

Using this slurry, a conventionally known doctor blade method, calender roll method, or rolling method,
It is formed into a sheet by a press forming method. Then, after a through-hole is formed in this sheet-like molded body as required, a metal paste is filled in the through-hole. Then, a wiring pattern is printed and applied on the surface of the sheet-like molded body using a metal paste by a known printing method such as a screen printing method or a gravure printing method so that the thickness of the wiring layer is 5 to 30 μm. . Thereafter, the plurality of sheet-shaped molded bodies are aligned and laminated and pressed, and then fired at an arbitrary temperature and atmosphere, whereby a wiring board can be manufactured.

When W or Mo is mainly used as the metal paste, firing is preferably performed in a reducing atmosphere, and when Cu or Ni is a main component, firing is preferably performed in a non-oxidizing atmosphere such as N _2. , Ag or Au,
Baking in an oxidizing atmosphere or a non-oxidizing atmosphere such as in the air is possible. When the metal paste is mainly composed of Cu, the firing temperature is desirably 1050 ° C. or lower, and when the main component is Ag, the firing temperature is desirably 950 ° C. or lower.

On the surface of the wiring board, a semiconductor element is mounted and connected to a wiring layer so that signals can be transmitted. As a connection method, the semiconductor element is connected to the wiring layer by directly mounting it on the wiring layer, or by wire bonding, flip chip, or the like.

Further, if necessary, a cap made of the same kind of insulating material as the insulating substrate, another insulating material, or a metal having good heat dissipation properties may be provided on the surface of the wiring board on which the semiconductor element is mounted, by glass, resin, or brazing. By bonding with an adhesive such as a material or sealing with a resin, the semiconductor element can be hermetically sealed and a package for housing a semiconductor element can be manufactured.

(Structure of Wiring Board) Next, the structure of the wiring board manufactured by the above-described method will be described with reference to the schematic sectional view of FIG. According to FIG. 1, the wiring board 1 is
A plurality of insulating layers 2 made of the above-mentioned ceramic sintered body
a, a wiring layer 3 is formed on the surface and inside of an insulating substrate 2 made of a laminate of 2b.

The wiring layer 3 is mainly composed of a conductive material such as a metal, and is selected from the group consisting of copper, silver and gold in order to increase the signal transmission speed and, in particular, to reduce the transmission loss of high-frequency signals. It is desirable to be made of a sintered metal paste containing at least one low-resistance metal as a main component, a high-purity metal having a purity of 99% or more, and a metal foil.
Further, according to FIG. 1, the wiring layers 3 formed on both surfaces of the insulating layer 2a and the insulating layer 2b are electrically connected by the via hole conductor 4.

According to FIG. 1, an element 5 such as a semiconductor element such as Si, Si-Ge or Ga-As is mounted on the surface of the insulating substrate 2. The heat generated by the operation can be radiated to the outside of the insulating substrate 2 via the insulating substrate 2 and the insulating substrate 2
The mechanical strength of the wiring board 1 can be increased by increasing its own mechanical strength.

When transmitting a high-frequency signal to the element 5 and the wiring layer 3, particularly a high-frequency signal of 1 GHz or more, and furthermore, 20 GHz or more, the wiring layer 3 is formed of a strip line to reduce the transmission loss of the high-frequency signal. It is desirable to be composed of one of a microstrip line, a coplanar line and a dielectric waveguide.

[0034]

EXAMPLES (Example) A having a purity of 99% and an average particle diameter of 2 μm
1N powder and Si _{3 having a} purity of 98% and an average particle size of 2 μm.
N ₄ powder was spread on a belt conveyor moving at a speed of 1 cm per second, and 5 normal pressure plasma irradiators having a length of 2 cm and a width of 3 cm were arranged in two rows at intervals of 2 cm (pitch of 4 cm). Plasma was irradiated to the ceramic powder inside. In addition, as for the plasma output method, ON / OFF switching was performed with a pulse output of 10 ms, and atmospheric plasma was irradiated under normal temperature and normal pressure atmosphere.

Next, the following two types of glass powder (glass A and glass B) were added to the ceramic powder or the ceramic powder not subjected to the plasma treatment in the ratio shown in Table 1 and mixed. , An organic binder, a plasticizer,
After toluene was added to prepare a slurry, a green sheet having a thickness of 300 μm was prepared using the slurry by a doctor blade method. Glass A: SrO32 wt% -SiO ₂ 24 wt% -ZnO16 wt% -B ₂ O ₃ 13 wt% -Al ₂ O ₃ 7 wt% -MgO8 wt% Glass B: SiO ₂ 24 wt% -Al ₂ O ₃ 10 wt% -ZnO15 wt% -B ₂ O ₃ 18 wt% -BaO28 wt% -CaO5 wt% then, the pressure of the green sheet laminating a plurality to a desired thickness, 10 MPa at a temperature of 60 ° C. In addition, thermocompression bonding was performed. After debinding the obtained laminate at 500 ° C. in the air, it was fired in the air under the conditions shown in Table 1 to obtain a ceramic sintered body.

The bulk density of the obtained sintered body was measured by the Archimedes method and calculated as a relative density to the theoretical density.
Further, the obtained sintered body was processed into a diameter of 10 mm and a thickness of 1.5 mm, and the thermal conductivity was measured by a laser flash method. Further, the sintered body was processed into a size of 3 mm × 4 mm × 50 mm, and the three-point bending strength was measured using an autograph. The results are shown in Table 1.

[0037]

[Table 1]

As is evident from the results in Table 1, Sample No. 1 was subjected to plasma treatment by providing a step of irradiating the surface of the ceramic powder with plasma according to the present invention.
Sample Nos. 2, 4, 5, 7, 8, 10 to 15 are samples for which plasma treatment of ceramic powder is not performed. It was found that higher relative density, flexural strength, and thermal conductivity were obtained as compared with 1, 3, 6, and 9.

Example 2 Sample No. 1 of Example 1 A green sheet was prepared by mixing a ceramic powder and a glass powder which had been plasma-treated at a ratio of 7, a via hole was formed at a predetermined position of the green sheet, and a metal paste containing Cu as a main component was filled to form a via hole conductor. After that, a wiring layer was formed using a metal paste containing Cu as a main component while being positioned with the via-hole conductor by a screen printing method.

Then, six green sheets on which the via-hole conductors and the wiring layers are formed are laminated while being aligned, pressed at 60 ° C. and 10 MPa, and then subjected to a binder removal treatment at 700 ° C. in a steam-containing nitrogen atmosphere. , 9
It was baked at 00 ° C. for 1 hour to produce a wiring board.

A semiconductor element was mounted on the surface of the obtained wiring board, and the connection state between the wiring layer and the semiconductor element in the wiring board was confirmed. As a result, a good conductivity of 3.0 μΩ · cm was confirmed. Was.

Example 3 The same procedure as in Example 1 was carried out except that sintering aid components of the type and amount shown in Table 2 were added to the ceramic powder of Example 1 and calcined at the temperature shown in Table 2. Similarly, a ceramic sintered body was prepared and similarly evaluated. The results are shown in Table 2.

[0043]

[Table 2]

From the results in Table 2, it is found that the sample No. in which the ceramic powder was not subjected to the plasma treatment 16 and sample N
o. For Sample No. 20, which was subjected to plasma treatment, 1
7 to 19 and 21 to 23 were found to have a high relative density and to improve both the bending strength and the thermal conductivity.

[0045]

As described in detail above, according to the present invention, in producing a ceramic sintered body, the surface of the ceramic powder is subjected to plasma treatment, and is molded and fired.
Since it can be fired at a low temperature or can be densified by reducing the amount of the sintering aid powder or glass powder, various properties such as thermal conductivity and bending strength of the ceramic sintered body can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an example of a package for housing a semiconductor element manufactured by using the method for manufacturing a ceramic sintered body of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 2 Insulating board 2a, 2b Insulating layer 3 Wiring layer 4 Via hole conductor 5 Element

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 4G001 BA01 BA02 BA03 BA04 BA05 BA06 BA07 BA08 BA32 BA36 BB01 BB02 BB03 BB04 BB05 BB06 BB07 BB08 BB32 BB36 BC01 BC02 BC13 BC17 BC22 BD14 BE33 4G030 AA08 AA09 AA10 AA11A32A CA08 GA01 GA06 GA14 GA15 GA20

Claims (9)

[Claims] 1. A method for producing a ceramic sintered body, comprising: subjecting a surface of a ceramic powder to a plasma treatment; 2. The method for producing a ceramic sintered body according to claim 1, wherein said plasma is atmospheric plasma or nitrogen plasma, and said plasma irradiation is performed in an oxidizing atmosphere. 3. The method for producing a ceramic sintered body according to claim 1, wherein the plasma is irradiated at room temperature under normal pressure. 4. The method for producing a ceramic sintered body according to claim 1, wherein said ceramic powder is a non-oxide powder. 5. The method for manufacturing a ceramic sintered body according to claim 1, wherein the thickness of the ceramic powder is modified from 0.05 to 50 nm from the surface of the ceramic powder by the plasma. 6. The ceramic firing method according to claim 1, wherein the amount of attached --OH groups attached to the surface of the ceramic powder after the plasma treatment is larger than the amount attached before the plasma treatment. The method of manufacturing the aggregate. 7. A glass ceramic characterized by mixing a glass powder and a ceramic powder produced by the method for producing a ceramic sintered body according to any one of claims 1 to 6, followed by molding and firing. Manufacturing method. 8. The method according to claim 7, wherein the glass powder is mixed at a ratio of 30 to 70% by weight and the ceramic powder is mixed at a ratio of 30 to 70% by weight. 9. The glass ceramic has a relative density of 95.
%. The method for producing a glass ceramic according to claim 7, wherein the amount is not less than 10%.