JP3363227B2 - Manufacturing method of ceramic sintered body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic sintered body and a manufacturing apparatus using the method, and particularly to a method for manufacturing a ceramic sintered body capable of ensuring high dimensional accuracy and high reliability, and manufacturing. Regarding the device.

[0002]

2. Description of the Related Art Since ceramics are generally high in processing cost, it is preferable to sinter the ceramic sintered body in a shape as close to the final dimension as possible. In addition, a semiconductor chip is mounted on a ceramic circuit board, etc., and in order to form a large number of electrical connections with the chip, the position of the wiring (connection terminals with the semiconductor chip) formed on the surface of the board must be highly accurate. Is mandatory. However, ceramics generally undergo a large dimensional change (shrinkage) during firing, and this shrinkage amount is easily affected by variations in raw materials and processes, and therefore it is a very difficult technique to maintain high dimensional accuracy after sintering.

A general method for producing a ceramic sintered body is as follows.
First, a ceramic powder containing a binder is molded into a predetermined shape or is machined after molding to have a predetermined shape. In the case of a circuit board or the like, a ceramic insulating layer and a multilayer laminate (molded body) in which a layer serving as a conductor is formed on at least the surface or the inside of the ceramic insulating layer are produced and then fired. The firing process basically consists of a process of removing the binder added for molding the ceramic powder (debinding process), a sintering process, and a cooling process. It is generally performed by pressure baking). However, this method cannot avoid variations in the firing shrinkage amount as described above, and it is very difficult to stabilize the dimensional accuracy of the substrate after firing with high accuracy. In particular, in the case of a circuit board having a complicated conductor layer inside, it is more difficult to secure the dimensional accuracy thereof, and further, warpage, swelling, and peeling between layers of the sintered body are major problems. Become.

In order to address these problems, the inventors of the present invention disclosed in Korean Patent Publication No. 92-6255 sinter a molded body (laminate) while applying a constant pressure through a binder removal process and a sintering process. Or a method of performing the binder removal step without pressure and then sintering it under a constant pressure. With this method, the amount of sintering shrinkage itself on the pressed surface of the sintered body can be suppressed small, and as a result, the dimensional variation after firing can be stabilized relatively easily within ± 0.5%, and It was shown that the warp, peeling, and blistering of the ties can be reduced.

[0005]

Further, the inventors of the present invention have subsequently developed a method for producing a sintered body with higher dimensional accuracy,
In addition, from the viewpoint of environmental resistance, the improvement of the binder has been studied aiming at the production of the laminate by a process using a water-soluble or water-dispersible binder without using a special organic solvent. As a result, in particular, in order to control the dimensional change rate after firing (sintered body) compared with before firing (molded body) within ± 0.3% with higher accuracy, a certain kind of binder material was used. In this case, it has been found that the pressurizing method disclosed in the above publication cannot be realized. As a result of investigating this cause,
It was found that a certain type of binder generated a considerably large shrinking force, which was not expected in the past, during debinding. Moreover, this force is much larger than the shrinking force generated during the sintering (densification) of ceramics, and the dimensional change during binder removal cannot be suppressed by the conventional process in which the sintering is performed under the conditions of constant pressure that is optimal for the sintering process. It turned out to be a good thing.

On the other hand, in order to utilize the ceramic sintered body with reliability in various applications, it is essential to reduce defects in the sintered body and increase the strength to improve the reliability. Therefore, it is important to reduce the amount of voids in the final sintered body that become defects and to reduce the diameter of the voids. The above-mentioned binder added for molding is preferably completely removed from the ceramic molded body in the binder removal step during the firing step, but in reality, some organic components are carbonized to form residual carbon. It remains in the molded body, which causes the generation of voids in the sintered body in the sintering process, and carbon itself acts as a defect in the sintered body. Therefore, it is important to reduce the residual carbon amount in the binder removal step as much as possible.

Therefore, the present invention improves the dimensional accuracy of the ceramic sintered body more than ever before through the binder removal step and the sintering step, and the residual carbon amount in the sintered body,
An object of the present invention is to provide a method for manufacturing a ceramic sintered body for reducing the void amount and the void diameter to improve the reliability of the sintered body, and a manufacturing apparatus using the manufacturing method.

[0008]

In order to achieve the above object, in the present invention, a forming step of forming a formed body containing a ceramic powder and a binder, and heating the formed body to remove the binder, In the method for manufacturing a ceramic sintered body, which further comprises a firing step of heating the shaped body to obtain a sintered body, and cooling the sintered body in this order, the firing step comprises:
In the step, there is a predetermined period for applying pressure to the molded body, and the pressure is set to be lower than the initial period of the period at the end of the period. A method for manufacturing a ceramic sintered body is provided.

Further, according to the present invention, a molded body manufacturing step of manufacturing a molded body containing ceramic powder and a binder, and a binder removal step of heating the molded body to remove the binder,
In the method for producing a ceramic sintered body, which comprises a sintering step of heating the molded body to form a sintered body and a cooling step of cooling the sintered body in this order, the binder removal step is performed on the molded body. There is provided a method for producing a ceramic sintered body, which is carried out while applying pressure, and the pressure is applied so as to be lower than that at the beginning of the process at the end of the process.

Further, according to the present invention, a molded body manufacturing step for manufacturing a molded body containing ceramic powder and a binder, a binder removal step for heating the molded body to remove the binder, and a heating for the molded body. In a method for producing a ceramic sintered body, which comprises a sintering step of forming a sintered body and a cooling step of cooling the sintered body in this order, the sintering step is performed while applying a pressure to the molded body while controlling a temperature. In a step of changing the temperature from a low temperature range to a high temperature range and performing firing, and the pressure applied in the low temperature range is higher than the pressure applied in the high temperature range. Provided.

Further, according to the present invention, a heating and firing mechanism having a furnace for heating and firing a molded body containing ceramic powder and a binder, a pressure applying mechanism for applying a pressure to the molded body during heating and firing, and the above heating A control device for controlling the firing mechanism and the pressure application mechanism and for performing binder removal and sintering in the heating and firing is provided, and the control device has a predetermined first temperature range in the furnace. Then, after applying a predetermined first pressure to the molded body and holding it for a predetermined time, the inside of the furnace is brought to a second temperature range higher than the first temperature range, and the molding is performed. An apparatus for producing a ceramic sintered body is provided, which has means for applying a second pressure smaller than the first pressure to the body and holding the second pressure for a predetermined time.

Further, in the present invention, a heating and firing mechanism including a furnace for heating and firing a molded body containing a ceramic powder and a binder, a pressure applying mechanism for applying a pressure to the molded body during heating and firing, and the above heating A control device for controlling the firing mechanism and the pressure application mechanism and for performing binder removal and sintering in the heating and firing is provided, and the control device has a predetermined first temperature range in the furnace. Then, after applying a predetermined first pressure to the molded body and holding it for a predetermined time, the inside of the furnace is brought to a second temperature range higher than the first temperature range, and the molding is performed. Applying a second pressure lower than the first pressure to the body and holding the binder for treating for a predetermined time, and setting the inside of the furnace to a third temperature range higher than the second temperature range, Above Body higher than the second pressure to the third
An apparatus for producing a ceramic sintered body is provided, which comprises: a sintering treatment means for applying a pressure of 1) and holding the pressure for a predetermined time.

[0013]

The above-described object is to apply a pressure to the outer surface of the compact in at least the binder removal step and the sintering step in the firing step of the compact mainly composed of the ceramic powder containing the binder, and to apply the maximum in the binder removal step. This can be achieved by making the pressure applied to the pressure higher than the pressure applied in the sintering step, and changing the pressure applied during the binder removal step and the sintering step. In particular, in order to reduce the amount of residual carbon in the sintered compact, it is important to maintain the open porosity in the compact in the binder removal process to a certain value or more. Optimizing the firing process conditions or material composition to achieve this By selecting, the amount of residual carbon can be reduced.

The inventors first examined in detail the dimensional change in the binder removal step. FIG. 2 shows the weight reduction and the dimensional change behavior of the molded body (without pressurization of the molded body) accompanying the general removal of the binder in these binder removal steps. Note that FIG.
Is the XY direction when the temperature is raised at a constant speed (pressurization direction is Z
2 is a graph schematically showing a relationship 201 between a dimensional change and a temperature and a relationship 202 between a weight change and a temperature in a direction orthogonal to the Z axis when the axis is used.

The dimensional change is the temperature range in which most of the binder is decomposed and removed (shown as A in FIG. 2) and the temperature range in which a very small amount of the binder residue after that is slowly removed (shown as B in FIG. 2). It became clear that it occurred in two stages. The amount of residual carbon is 0.1% or less, preferably 0.05% or less in consideration of the influence on the void amount and diameter of the final sintered body, and it is necessary to have electrical insulation in applications such as electronic materials. In some cases, the content is preferably 0.03% or less, and in the present invention, the step of obtaining binder residues at these levels according to the application is considered to be the binder removal step. In order to achieve this, the maximum temperature in the binder removal step is preferably set as high as possible to promote the binder removal reaction. However, if the temperature is raised too much, the sintering of the ceramic material itself proceeds, and the compact becomes denser, so that the binder removal property decreases. Generally, as the maximum temperature of the binder removal process, it is often the case that the ceramic material itself begins to sinter slightly, but depending on the type of ceramic material, sintering shrinkage does not occur and the binder removal reaction is sufficient. There is no guarantee that the temperatures that occur in both will be compatible. The shrinkage in the high temperature range (temperature range B) in FIG. 2 also indicates that the sintering shrinkage of the ceramic material itself has started.

Further, the dimensional change (shrinkage) in the binder removal step was examined under the condition that a pressure was applied. When pressure is applied in a direction orthogonal to the two front and back surfaces of the plate-shaped molded product and the binder is removed at a constant rate to remove the binder, the pressure applied in the binder removal step and the XY direction (pressurized surface) FIG. 1 shows the relationship of dimensional change in the direction orthogonal to the direction).

When the applied pressure is small (shown as 102 in FIG. 1), the two-stage contraction described above is smaller than that in the case where no pressure is applied (shown as 101 in FIG. 1), but both occur. . If the applied pressure is increased (103 in FIG. 1)
Of the two stages described above, the second stage contraction (contraction in the temperature range B) can be suppressed to a small level.
The first-stage shrinkage (shrinkage in the temperature range A), that is, the shrinkage in the temperature range where most of the binder is rapidly decomposed and removed, still occurs. When the applied pressure is further increased (104 in FIG. 1)
Both of the above-mentioned two stages of contraction can be suppressed. This study has revealed that the shrinkage force of the molded body generated when most of the binder is rapidly decomposed and removed is considerably larger than the shrinkage force generated when the ceramic material itself sinters and shrinks.

When it is necessary to apply a large pressure to suppress the dimensional change in the binder removal step as described above,
If the sintering process is performed at the same pressure as it is, there is a problem that the applied pressure is too large and the sintered body is crushed, or the sintered body reacts strongly with the jig on the pressing surface or the side surface and is fixed. Will occur. Therefore, the pressure applied in the firing step should be sufficient in the binder removal step to correspond to a large shrinkage force, and should be smaller in the range that can prevent crushing during sintering and suppress sintering shrinkage of the pressing surface. It is effective to change the pressure.

Further, in the sintering step, the pressing force is increased in the region where crushing does not easily occur at a relatively low temperature at the beginning to reduce the void amount and the void diameter, and in the higher temperature region, the pressing force is applied to prevent the crushing. It is also effective to reduce the amount of heat and to perform sufficient firing. The porosity in the sintered body after firing is 3% or less, preferably 2% or less, and the void diameter is 10 μm or less, preferably 5 μm or less. Therefore, it is desirable to set the pressure in advance so as to realize the porosity and the void diameter, and to use the pressure for sintering.

On the other hand, even in the binder removal process, the first temperature range A for suppressing the first stage shrinkage of the binder removal process (shrinkage due to abrupt decomposition and removal of the binder). When the temperature is further increased to accelerate the binder removal while maintaining the applied pressure to the second temperature range B which is higher than the first temperature range A, the contraction accompanying sintering is also promoted, and the binder removal property is rather deteriorated. . It is considered that this is because the voids in the molded body were reduced by the sintering shrinkage, but the relationship with the binder removal property has not been known in detail so far.

[0021] Therefore, as a result of examining the relationship between the voids in the molded body and the binder removal property, the inventors have found that among the voids (open pores, closed pores) in the molded body, the open porosity and the open porosity of the molded body are particularly preferable. It was found that there is a close relationship between the pore size and the binder removal property. The relationship between the open porosity and the residual carbon amount is shown in FIG. 3, and the relationship between the open pore diameter and the residual carbon amount is shown in FIG.
The open porosity and the open pore diameter were measured by a mercury porosimetry porosimeter. As can be seen from these figures, the binder escape path from the inside of the molded body, which is connected to the outside of the molded body, that is, the amount of open pores is sufficiently secured, and the size of the open pores is kept large to remove the binder. Sex can be greatly improved. From the results of the above examination, the open porosity of the molded body should be maintained at 15% or more, preferably 20% or more, and the open pore diameter should be 0.2 μm or more, preferably 0.3 μm or more. It has become clear that this is effective for binder removal. Therefore, if the applied pressure is increased, the open porosity and the open pore diameter tend to be smaller.Therefore, a pressure that achieves the above open porosity and open pore diameter is set in advance and decompression is performed using the pressure. It is desirable to perform binder processing.

Therefore, in order to reduce the residual carbon more effectively, as a process condition that can realize the above conditions, the pressing force is changed during the binder removal process, more specifically, the binder removal process. In order to suppress the shrinkage (shrinkage in the temperature range A) due to the rapid decrease of the binder in the first step, first, the first step of firing under the first large applied pressure is performed, and then the first step is performed. It is effective to perform the second step of reducing the residual carbon by firing while maintaining the open porosity and the open pore diameter of the molded body under the second pressurizing force smaller than the pressurizing force. The pressing force required to suppress the dimensional change can be reduced as the binder removal amount increases.
Therefore, more specifically, a method is preferable in which the pressing force in the binder removal step is kept large until at least 50% of the binder is decomposed and removed, and then the pressing force is continuously reduced. In order to secure higher dimensional accuracy, it is preferable to apply the second pressing force after 80% of the binder has been decomposed and removed.

Further, the applied pressure depends on the amount and type of binder added,
Although it should be determined according to the size of the molded body,
The pressures which are sufficient to suppress the dimensional change and which do not damage the molded body are preferably in the following ranges. That is, the pressing force in the binder removal step is 0.5 to
100 kg / cm ² is preferred. The first applied pressure in the binder removal step is desirably 1 to 100 kg / cm ² , preferably 5 to 50 kg / cm ² . The second pressing force in the binder removal step is 0.5 to 10 kg /
It is desirable to set it to be cm ² , preferably 0.5 to 5 kg / cm ² .

On the other hand, the pressure applied during sintering is 1 to ²⁰ kg / cm ² , preferably 1.5 to 10 as a pressure sufficient for suppressing dimensional change and maintaining the shape of the molded body. 10 kg / cm ² is preferred. When changing the pressing force in the sintering process, the first pressing force is 2 to 2
0 kg / cm ^2, preferably desirably 1.5~10kg / cm ^2, the second pressure is 1 to 10 kg / cm ^2, preferably 1-5 kg / cm ² is desirable.

The maximum temperature of the binder removal process is 400
~ 1000 ℃, the maximum temperature in the sintering process is 700 ~ 170
It is desirable to be performed in the range of 0 ° C. If it is too low, sufficient densification does not occur, and if it is too high, the shape of the molded article cannot be maintained.

Further, the binder removal step is preferably carried out in an oxidizing gas atmosphere or a humidified inert gas atmosphere. After completion of the binder removal step in an oxidizing atmosphere, it is preferable to carry out a step of firing in a reducing atmosphere as the case may be. In that case, it is preferable that the reduction step is performed at the same temperature as that of the binder removal step or at a lower temperature, and under a pressure condition smaller than the maximum pressure applied in the binder removal step or without pressure. This is for suppressing the dimensional change in the reduction step, suppressing the progress of sintering shrinkage of the ceramics as much as possible, and sufficiently performing the reduction reaction. Even in this case, the open porosity of the molded body is 15%.
Above, it is preferable to maintain at 20% or more.

Generally, the required pressing force changes depending on the type of binder material, the addition amount, and the thickness of the laminated body, and increases as the thickness of the laminated body to be fired increases. Further, as a result of studying various binders, it was found that a particularly large shrinkage force is generated when at least a part of the binder produces a liquid substance in the thermal decomposition process during the binder removal process. Further, as a result of examining the liquid pyrolyzed binder, the main components thereof were the monomer or the oligomer thereof constituting the original polymer binder. In particular, a binder which is water-soluble or water-dispersible exhibits this characteristic.
It is considered that the large contraction force at the time of removing the binder is due to the force of the liquid viscous substance generated in the voids of the aggregate of the ceramic powder, and the surface tension thereof causing the ceramic powder to aggregate. As the binder for molding the ceramic powder, in addition to the binder that is most added to bond the ceramic powder to mainly impart moldability, a plasticizer,
A small amount of additives such as dispersants and defoamers may be added.

In the present application, the expression that the firing shrinkage of the surface to which the pressing force is applied is suppressed is the case where the rate of change compared with the dimension before firing is within ± 0.3%. This is because it is considered that the dimensional change can be substantially ignored if the rate of change is in this range. However, in the case of a ceramic sintered body that is used for applications such as mounting boards that require higher dimensional accuracy, the negligible range is within ± 0.2%, preferably within ± 0.1%. Sometimes it should be. The surface of the molded body to which the pressing force is applied is preferably the surface having the largest area among the plurality of surfaces of the molded body.

The member that is in contact with the molded body and transmits the pressing force is
Dimensionally stable and porosity of 50 at firing temperature of molded body
% Or more, and more preferably 70% or more of a porous material is preferable. This is to secure a path for the binder released from the molded body to escape into the atmosphere. Since the thermal decomposition / combustion components of the binder can be easily discharged to the outside from the upper and lower surfaces through this porous plate, the porous plate is placed on the upper and lower surfaces of the molded body and Sintering while applying pressure through it is effective for removing the binder (debinding). In particular, a porous plate obtained by compounding a heat-resistant ceramic fiber material (prepared by using a mixture of ceramic fibers and ceramic particles) is an effective material because it can suppress the decrease in strength and increase the open porosity. .

When surface smoothness is particularly required,
A slight processing may be performed after sintering by a method such as grinding. In this case, since the sample obtained by the method of the present invention has very small dimensional accuracy and warp of the entire sample, there is an advantage that a grinding amount can be small.

The molding is fired in an oxidizing, inert or reducing atmosphere or in a vacuum. Also,
The firing atmosphere may be changed stepwise to two or more of them. In particular, in the case of a wiring board or the like in which a conductive material having low oxidation resistance is used, A
A binder removal step in a humidified atmosphere gas such as r / H ₂ O, N ₂ / H ₂ O, N ₂ / H ₂ / H ₂ O is preferable. Performing the binder removal step in an oxidizing atmosphere such as in air is effective in shortening the binder removal step time. However, when using a conductive material having low oxidation resistance, a step of reducing the oxidized conductive material is required after the binder removal step is completed.
It is also effective to perform firing in a gas pressure atmosphere larger than atmospheric pressure in order to accelerate the binder removal property if necessary.

The ceramic compact firing apparatus of the present invention comprises:
At least a part of the firing step (including binder removal, sintering, and cooling) is provided with means for applying a pressing force to at least a part of the molded body, and at least the first step in the firing step.
Controlling a first step of applying a first pressurizing force in a temperature range of, and a second step of applying a second pressurizing force lower than the first pressurizing force in a second temperature range higher than the first temperature Means for doing so. Further, the present apparatus has a control device for controlling the pressing force and the temperature as described above at the same time. Also, when applying the pressing force to the molded body,
It is preferable to have a mechanism that can apply pressure without giving an impact to the molded body or a mechanism that applies a member for pressurizing the molded body to the molded body at a constant speed. If such a mechanism is provided, the molded body after debindering is very brittle, so if it is necessary to newly apply a pressure after the debindering step, the pressure is applied without causing cracks or the like. This is an effective way to do

As the ceramic material used in the present invention,
Ceramics containing alumina, mullite, silica, zirconia, aluminum nitride, boron nitride, silicon nitride, silicon carbide, sialon or a mixture thereof as a main component, various glasses such as borosilicate glass, aluminosilicate glass, cordierite, β- Crystallized glass containing crystals such as eucryptite, and these, alumina, silica, mullite, zirconia, magnesia, silicon nitride,
Mainly composed of composite materials with ceramic fillers such as silicon carbide, sialon, aluminum nitride, boron nitride, diamond, cordierite, β-eucryptite, and complex perovskite compounds containing barium titanate, lead titanate and other lead Various ceramics can be used, such as a material suitable for a capacitor and a piezoelectric element to be used.

Particularly, as the ceramic raw material powder composition,
The open porosity of the molded product is 15% at the end of the binder removal process.
The above materials are preferable, and the material composition is preferably such that the porosity of the sintered body after the firing step is 3% or less. These raw material powder materials have an open pore diameter of 0.2 μm or more after the binder removal step in the range of 400 to 1000 ° C., and a void diameter of 10 μm or less after the sintering step of 700 to 1700 ° C. The powder composition is preferable. As the ceramic powder composition satisfying the above conditions, a single powder or a mixture of different kinds of powder can be selected. In particular, a ceramic raw material powder composition comprising a mixture of glass powder and crystalline ceramic powder, and further having a mixing ratio of crystalline ceramic powder of more than 50 vol%,
It is particularly suitable as a powder composition satisfying the above conditions.

As the material for forming the conductor layer on the surface and inside of the ceramic sintered body, Cu, Ag, Au, Ag are used.
A material selected from / Pd, Ni, W, Mo, Pd, Pt or a combination thereof is suitable. The conductor material selected from the above combination may be used as an alloy in advance, or may be one which reacts during printing and firing to form an alloy in at least a part thereof. Further, it may be a composite material that does not substantially react with each other even after firing and exists integrally as a composite material. Thereby, the firing atmosphere, the thermal expansion coefficient, the electrical conductivity (resistivity), etc. can be widely selected as the conductor material.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. (Example 1) oxide in terms of the SiO ₂ 60 to 75 wt%, Al ₂ O ₃ 15 to 30 wt%, Li ₂ O and 10 wt% or less, the composition others and 15 wt% or less Lithium aluminosilicate glass powder 4 having an average particle size of 2 μm
5% by volume, 25% by volume of alumina powder having an average particle size of 1 μm, 30% by volume of mullite powder having an average particle size of 2 μm, a water-soluble modified acrylic binder, and water were added, and the mixture was wet-mixed in a ball mill for 24 hours to form a slurry. Was produced. This was poured into a molding die to produce a plate-shaped molded body.

This compact was placed in a furnace with an alumina fiber / mullite composite porous plate (porosity about 60%, average pore diameter 8 μm) sandwiched between the upper and lower surfaces, and 900 The binder was sufficiently removed by raising the temperature to ℃.
In this embodiment, the period of applying pressure includes the binder removal step, the sintering step, and the first 6 minutes of the cooling step. Pressure during the binder removal, until first boost at a rate of 0.3 kg / cm ² to 10 kg / cm ² at room temperature, of about 600 ° C. the temperature most of the binder is removed 10
A pressure of kg / cm ² was maintained. After that, the applied pressure is 0.2 per minute.
slowly reduced to 1 kg / cm ² and the temperature was raised to 900 ° C. at a rate of kg / cm ^2, and held for 10 hours. At this stage, the dimensional change of the pressing surface of the molded body did not occur. Then, the applied pressure was further changed to 3 kg / cm ² (pressurized at a rate of 0.5 kg / cm ² per minute), the temperature was raised to 1200 ° C. in nitrogen, and the mixture was held for 2 hours for sintering. After holding, release pressure (0.5 min / min)
While lowering the pressure at a rate of kg / cm ² ), the sintered body was cooled to room temperature.

The dimensional change rate of the surface pattern of the pressure surface of the obtained sintered body was 0.2% or less. Further, as a result of taking out and examining a part of the sample at the end of the binder removal step, the open porosity in the molded body was 18%, the open pore diameter was 0.25 μm, and the residual carbon amount decreased to 0.02%. Was there.

(Example 2) Converting to oxide, 6 of SiO ₂ was used.
5 to 85% by weight, B ₂ O ₃ to 10 to 30% by weight, Al ₂ O ₃
Of 0 to 15% by weight, alkali metal oxides of 10% by weight or less, and other components of 1% by weight or less, and 48% by volume of borosilicate glass powder having an average particle size of 3 μm, and alumina powder 15 having an average particle size of 1 μm. % By volume, 22% by volume of cordierite powder with an average particle size of 2 μm, and 15% by volume of silica glass powder with an average particle size of 2 μm, and further mixed with a modified acrylic binder, a plasticizer, a dispersant, and a solvent. Was added and wet mixed for 24 hours with a ball mill to prepare a slurry. Next, using this slurry, a green sheet was obtained by a doctor blade method. Holes of 50 to 100 μmφ were punched in these green sheets by a punching method, and Cu-based conductor paste was filled in the holes to form vias. Wiring was also printed on the green sheet using a Cu-based paste. Forty-five green sheets printed with these various wiring circuits are stacked at 120 ° C, 150 kg / c
By thermocompression bonding under the condition of m ² , a multi-layer ceramic laminate having wiring formed in a three-dimensional shape was produced.

A mullite composite porous plate (a porosity of about 70%, a pore diameter of 12 μm) prepared by mixing this laminate with alumina fibers.
The upper and lower surfaces were sandwiched by m), and pressure was further applied from above to raise the temperature to 15 kg / cm ² at room temperature at a rate of 0.5 kg / cm ² . At this pressure, 80% or more of the binder is removed 50
It was kept in a nitrogen atmosphere up to 0 ° C. After that, the atmosphere,
A mixed gas stream of nitrogen, hydrogen, and water vapor, and a temperature of 85
0 decreases gradually applied pressure at a rate of 0.1 kg / cm ² until the temperature is raised to ° C. until 1 kg / cm ^2, and treated binder removal holding at 850 ° C. 20 hours. At this time, the binder was sufficiently removed by raising the temperature at a slow rate of 100 ° C./h or less and further increasing the gas atmosphere pressure above the atmospheric pressure to promote the diffusion of the humidified gas into the inside of the laminate. . 8
After the binder removal process is completed at 50 ° C., the first pressure without changing the temperature 10 kg / cm ² (boosting per minute 0.2 kg / cm ² speed)
And then, then was held for 2 hours at a heating to 950 ° C., and (Buck at a rate of 0.3 kg / cm ²⁾ the pressure 2 kg / cm ²
Was maintained at 1050 ° C. for 2 hours. This pressure was maintained even in the cooling step after sintering.

The void amount in the sintered body thus obtained was very small, 1% or less, and the void diameter was 5 μm or less. No large crushing of the sintered body was observed, and the Cu conductor portion formed inside was also sintered very densely. A part of the sample was taken out and examined at a time point after being held at 950 ° C. for 2 hours in the first half of the sintering process, and as a result, the void amount and the void diameter were almost the same as the state of the final sintered body, but they were formed inside. Some large voids were found in the Cu conductor portion.

(Embodiment 3) Converting to oxide, 6 of SiO ₂ is used.
5 to 85% by weight, B ₂ O ₃ to 10 to 30% by weight, Al ₂ O ₃
Of 0 to 10% by weight, alkali metal oxides of 10% by weight or less, and other components of 1% by weight or less, 65% by volume of borosilicate glass powder having an average particle size of 3 μm, and an average particle size of 2
15% by volume of alumina powder having a particle diameter of 2 μm and 20% by volume of cordierite powder having an average particle diameter of 2 μm are mixed, and two kinds of binders are added to the mixed powder in an amount of 1 with respect to the ceramic powder.
5 parts by weight each were added. As the binder, a water-soluble modified acrylic binder in which a part of the thermal decomposition product becomes liquid and a methacrylic acid-based binder with little liquid product were used. A small amount of a plasticizer, a dispersant, a defoaming agent, and a solvent containing water were added to each, and wet-mixed for 24 hours in a ball mill to prepare two types of slurries. Next, using this slurry, a green sheet was obtained by a doctor blade method. These green sheets are punched with 100
A hole having a diameter of ˜150 μm was opened, and a conductor paste of Cu was filled in the hole to form a via. C on the green sheet
Wiring was printed using u paste. Forty green sheets printed with these various wiring circuits are stacked,
By thermocompression bonding under the conditions of 100 ° C. and 150 kg / cm ² , a multilayer ceramic laminate having wiring formed in a three-dimensional shape was produced.

This laminated body was formed into upper and lower two alumina / silica composite porous plates (porosity about 70%, average pore diameter 10 μm).
m), and in the binder removal step, while applying a constant pressure of ² to 8 kg / cm ² respectively, apply nitrogen / humidification
Firing was performed at 700 ° C. for 50 hours in a hydrogen atmosphere. In the subsequent sintering process, while applying a pressure of ² kg / cm ² ,
Firing was performed at 950 ° C. for 1 hour in a nitrogen atmosphere, and cooling was performed while maintaining the applied pressure.

Table 1 shows each pressing force at the time of debinding, the dimensional change rate of the pressing surface (XY direction) after the debinding process, and the dimensional change rate after sintering at a pressing force of 2 kg / cm ^2. Indicated.
When using a methacrylic acid-based binder, the dimensional change during binder removal is 0.2% at a pressure of ² kg / cm ² , which is the same as the optimum pressure for sintering. In the case of using the modified acrylic binder contrast, can not be completely suppressed shrinkage in pressure of 2 kg / cm ^2, the first dimension was a 8 kg / cm ² by increasing further the pressing force The change was 0.2% or less.

[0045]

[Table 1]

(Example 4) Mullite (3Al ₂ O ₃ .2S)
iO _2: average particle size 3 [mu] m) 70 to 80 wt%, SiO ₂ 20 to 30% by weight as a sintering aid, Al ₂ O ₃ 0.3 to 10 wt%, in MgO0.3~2 wt%, the total amount A modified acrylic binder, a plasticizer and a solvent were added to 100% mixed powder and wet mixed for 24 hours with a ball mill to prepare a slurry. A green sheet was prepared in the same manner as in Example 3,
A wiring circuit and an electrode layer were formed on the via and the green sheet by using the W conductive paste. A large number of green sheets printed with these various kinds of wiring circuits were laminated and thermocompression-bonded to produce a multilayer ceramic laminate having wiring formed in a three-dimensional shape.

This laminate has a surface roughness (Ra) of about 2-3.
It was placed in a furnace sandwiched by a boron nitride plate of μm, heated to 1000 ° C. in a mixed gas stream of nitrogen, hydrogen, and steam to sufficiently remove the binder. In this binder removal process, the laminated body is pressurized to 10 kg / cm ² up to about 800 ° C. at which most of the binder is removed, and then the applied pressure is slowly reduced to 5 kg / cm ² to 1000 ° C. The temperature was raised to. At this stage, the dimensional change of the pressure surface of the laminate did not occur.

Thereafter, while applying a pressure of 5 kg / cm ² ,
Sintering was performed at 1600 ° C. for 5 hours in a mixed gas stream of nitrogen, hydrogen and steam. Immediately after the holding, the pressure was released and the sample was rapidly cooled. The dimensional change rate of the pressing surface pattern of the obtained ceramic multilayer circuit board was 0.2% or less.

(Embodiment 5) The amount of SiO ₂ converted to oxide is 6
5 to 85% by weight, B ₂ O ₃ to 10 to 30% by weight, Al ₂ O ₃
Of 0 to 15% by weight, alkali metal oxides of 10% by weight or less, and other components of 1% by weight or less and 55% by volume of borosilicate glass powder having an average particle size of 3 μm, and alumina powder 10 having an average particle size of 1 μm. % By volume, 25% by volume of cordierite powder having an average particle size of 2 μm, and 10% by volume of quartz glass powder having an average particle size of 1 μm, and further mixed with a water-soluble modified acrylic binder, a plasticizer, and a dispersion. The agent and water were added and wet-mixed for 24 hours with a ball mill to prepare a slurry. Next, a green sheet was formed by the same method as in Example 3, and wiring was printed on this using a Cu conductor paste by a printing method. A laminate was prepared by laminating 40 of these green sheets.

This laminated body was sandwiched between two upper and lower cordierite porous plates (porosity about 60%, average pore diameter 5 μm, coefficient of thermal expansion 3.5 × 10 ⁶ / ° C.), and further above it. 10kg up to 350 ° C where about 80% of the binder is removed from
A pressure of / cm ² was applied, and then the pressure was changed to 3 kg / cm ² , the temperature was raised to 800 ° C. in a mixed gas stream of nitrogen, hydrogen and steam, and the temperature was maintained for about 20 hours for binder removal treatment. In this binder removal treatment, the binder is removed by raising the temperature at a slow rate of 100 ° C./h or less and further increasing the gas atmosphere pressure above atmospheric pressure to promote the diffusion of the humidified gas into the laminate. Well done. Sintering pressure 2
It was carried out by holding at 950 ° C. for 2 hours at kg / cm ² . The dimensional change rate of the surface layer pattern of the sintered body is 0.1%
Met.

(Example 6) Converting to oxide, 4 of SiO ₂ was used.
0-60 wt%, B ₂ O ₃ 0-10 wt%, Al ₂ O ₃ 10-35 wt%, MgO 5-25 wt%, CaO 0
To 25% by weight, 0 to 5% by weight of alkali metal oxide, and a water-dispersible methacrylic acid binder and a plasticizer to a glass powder (average particle size 2 μm) of a crystallized glass composition selected so that the total amount is 100%. Then, a dispersant and a solvent containing water were added and wet mixed for 24 hours with a ball mill to prepare a slurry. In the same manner as in Example 3, a multilayer ceramic laminate having Cu wiring formed in a three-dimensional shape was produced.

This laminated body was placed on an alumina / mullite porous plate, a similar porous plate was placed on the upper surface, and a pressure of 20 kg / cm ² was applied from the top of the porous plate to the atmosphere, The binder removal treatment was performed at 600 ° C. for 3 hours.

Thereafter, the conductor portion was continuously subjected to reduction treatment in hydrogen / nitrogen gas at 600 ° C. for 3 hours.
In this reduction step, the pressure applied was 1 kg / cm ² .

Next, after applying a pressure of 3 kg / cm ² and heating at 900 ° C. for 2 hours mainly for densification of the substrate, for further crystallization treatment of the substrate part and final densification of the conductor and the substrate part. The sample was heat-sintered under the conditions of a pressing force of 2 kg / cm ² and 950 ° C. for 1 hour. After that, gradually increase the pressure (1 kg / min /
cm ² ) Cooling while decreasing.

The rate of dimensional change in the X and Y directions of the surface layer of the obtained ceramic multilayer circuit board was measured after removing the binder, after reducing, and after sintering.

(Embodiment 7) Next, an embodiment using a ceramic sintered body manufacturing apparatus will be described. The configuration of the ceramic sintered body manufacturing apparatus of this example is shown in FIG. The ceramic sintered body manufacturing apparatus according to the present embodiment includes a heating and firing unit 10 for heating and firing the molded body 2, a transport mechanism (not shown) for transporting the molded body 2, feeding it into the furnace 1, and taking it out. A pressure applying mechanism 20 for applying a pressure to the molded body 2 therein,
Heating / baking mechanism 10, transport mechanism, and pressure applying mechanism 20
It has a control mechanism (control device) 7 for controlling the above and a power source (not shown) for supplying electric power to each of the above mechanisms.

The heating / firing mechanism 10 includes a furnace 1, a heater 3 for raising the temperature in the furnace 1, a voltage controller 4 for controlling the voltage applied to the heater 3, and an atmosphere in the furnace. The atmosphere adjusting unit 11 and a temperature sensor (not shown) that measures the temperature inside the furnace 1 are provided. The atmosphere adjusting unit 11 includes a cylinder that holds various gases, and includes means for changing the atmosphere in the furnace 1 to a mixed airflow atmosphere of nitrogen, hydrogen, and steam, or a dry atmosphere.

The transport mechanism is provided with a motor section (not shown) and operates by driving the motor section. Further, the door (not shown) of the furnace 1 is adapted to open and close as the molded body is moved by the transfer mechanism.

The pressure applying mechanism 20 holds the molded body and applies a pressure, a pressure applying section 5, an actuator 6 for moving the pressure applying section 5 up and down, and a pressure applied by the pressure applying section 5. Pressure sensor (not shown). The pressure applying section 5 has two press plates 9 for holding the compact 2 and the press plate 9 vertically holds the compact 2.

The control mechanism 7 is connected to the voltage control section 4, the actuator 6, and the motor section of the transport mechanism by signal lines, and controls these devices via control signals. The control mechanism 7 includes a central processing unit and a storage device,
Perform processing according to a predetermined procedure. The processing flow of the control mechanism 7 is shown in FIG.

First, the control mechanism 7 conveys to the conveyance mechanism to a predetermined position (predetermined position on the lower press plate 9) in the compact body furnace 1 which is set at a predetermined position of the conveyance mechanism in advance. , Are set (step 601). In this example, as a molded body, the multilayer ceramic laminate 2 to be fired was sandwiched between two holding plates 8 and subjected to pressure and heat treatment. Further, since the control mechanism 7 applies pressure without giving an impact to the laminated body 2, the control mechanism 7 instructs the actuator 6 to start rising of the lower press platen 9 at a speed of 0.5 mm / min (step 602), the pressure applied to the molded body is the initial pressing pressure (0.05 kg / cm).
^{When the} pressure sensor detects that ( ² ) has been reached (step 603), it instructs the actuator 6 to stop the lifting of the lower press platen 9 (step 604). Next, the control mechanism 7 controls the actuator 6, the voltage controller 4 of the heater 3, and the atmosphere adjuster 11 to remove the binder (step 605) and the sintering (step 606).
To execute. As a result, when the sintering is completed, the control mechanism 7 instructs the actuator 6 to return the lower press platen 9 to the initial position (the position at the time of executing step 601) (step 607), and causes the transfer mechanism to move the molded body. Is removed from the furnace (608).

The above binder removal processing (step 605)
The flow of is shown in FIG. In the binder removal processing, first,
The control mechanism 7 causes the actuator 6 to have a flow rate of 0.5 kg / min.
Instruct to start pressurization at a speed of cm ² (step 70
1), the pressure of the press board 9 is 10 kg /
When it detects that it has reached cm ² (step 702),
The actuator 6 is instructed to stop boosting, and the pressure holding process is started (step 703). Here, the pressure holding process is a process of performing a feedback process in accordance with an input from the pressure sensor and constantly maintaining a constant pressure until the pressure holding is stopped. Pressure application part 5
Such a treatment is necessary in order to suppress the pressure fluctuation due to the thermal expansion of the.

Next, the control mechanism 7 controls the voltage control unit 4 to have one
When the temperature sensor detects that the temperature inside the furnace 1 has reached 500 ° C. (step 705), the control mechanism 7 controls the atmosphere. The section 11 is instructed to set the atmosphere in the furnace 1 to be a mixed air stream of nitrogen, hydrogen, and steam (step 706). Further, the control mechanism 7 stops the pressure holding and instructs the actuator 6 to reduce the pressure at a rate of 0.1 kg / cm ² per minute (step 707). Control mechanism 7
When the temperature in the furnace 1 reaches 800 ° C., the voltage control unit 4 is instructed to stop the temperature rise and the temperature holding process is started. When the pressurization of the press platen reaches 0.5 kg / cm ² , the actuator Is instructed to stop the pressure reduction and the pressure holding process is started (step 708). It should be noted that the temperature holding process is, like the pressure holding process described above, a process of performing a feedback process according to an input from the temperature sensor and maintaining the temperature inside the furnace 1 constant until the temperature holding is stopped. Finally, the control mechanism 7 waits for 50 hours while keeping the temperature and the pressure, and finishes the binder removal processing (step 7).
09).

When the binder removal processing is completed, the control mechanism 7
Performs the sintering process (step 606). The flow of the sintering process is shown in FIG. In the sintering process, first, the control mechanism 7 instructs the atmosphere adjusting unit 11 to make the inside of the furnace 1 a dry nitrogen atmosphere (step 801). Next, the control mechanism 7 stops holding the pressure (while continuing to start in step 708 of the binder removal processing), and instructs the actuator 6 to start increasing the pressure at a rate of 0.2 kg / cm ² per minute ( In step 803), when the pressure sensor detects that the pressurization of the press platen 9 has reached 8 kg / cm ² (step 8).
03), the actuator 6 is instructed to stop the pressurization, and the pressure holding process is started (step 804). Further, the control mechanism 7 stops keeping the temperature in the furnace 1 (similar to the pressure keeping and continues to start at step 708 of the binder removal processing) and causes the voltage control unit 4 to increase the speed at 100 ° C./hour. When the temperature sensor gives an instruction to start the temperature (step 805) and the temperature sensor detects that the temperature in the furnace 1 has reached 1050 ° C. (step 806), the voltage controller 4 is instructed to stop the temperature rise, and the temperature holding process is performed. Is started (step 807). Control mechanism 7
Waits for 2 hours while keeping the temperature and the pressure (step 808), stops the temperature keeping, and instructs the voltage controller 4 to start the temperature reduction (step 809).
When the temperature inside the furnace 1 reaches room temperature (step 810), the control mechanism 7
Stops holding pressure and puts 1 kg / min on the actuator 6.
Instruct to start the step-down at a speed of / cm ² (Step 81
1) When the press plate 9 is no longer pressed, the sintering process is finished (step 812).

In this embodiment, the holding plate 8 is 210 mm × 2, which is obtained by mixing and firing alumina fiber and silica powder.
Composite porous plate with a size of 10 mm x 10 mm (porosity 7
0%) was used. In addition, the multilayer ceramic laminate 2 includes
A multilayer ceramic laminate having a size of 200 mm × 200 mm × 10 mm was used. This multilayer ceramic laminate is
It was produced as follows. That is, in terms of oxide, 65 to 85% by weight of SiO ₂ , 10 to 30% by weight of B ₂ O ₃ , 0 to 15% by weight of Al ₂ O ₃ , 10% by weight or less of alkali metal oxide, and others 48% by volume of borosilicate glass powder having an average particle size of 3 μm and having a composition of 1% by weight or less
12% by volume of silica powder having an average particle size of 2 μm and 40% by volume of mullite powder having an average particle size of 2 μm are mixed, and a modified acrylic binder, a plasticizer, a dispersant, and a solvent are added to the powder. , Cu in the same manner as in Example 2
A multi-layer ceramic laminated body in which system wiring was formed three-dimensionally was produced.

The dimensional change rate of the pattern of the pressing surface of the ceramic multilayer circuit board obtained by firing using the ceramic sintered body manufacturing apparatus of this example was 0.2% or less.

When no pressure is applied in the sintering process or when the pressure in the binder removal process is not changed, the control mechanism 7 controls the inside of the furnace in a predetermined first temperature range. Then, after applying a predetermined first pressure to the molded body and holding it for a predetermined time, the inside of the furnace is brought to a second temperature range higher than the first temperature range, and A means for applying a second pressure smaller than the pressure of 1 and holding the pressure for a predetermined time is enough. As in the present embodiment, the third pressure is further applied and the third pressure is applied in advance. There is no need to have a means for holding for a fixed time.

When the temperature and the pressure are changed in two steps in the sintering process, the control mechanism 7 further changes the temperature and the pressure after the step 808 of the sintering process of the present embodiment, and the furnace is changed. Inside the fourth temperature higher than the third temperature range
The temperature range may be set to, and a means for applying a fourth pressure smaller than the third pressure to the molded body and holding it for a predetermined time may be further provided.

[0069]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a sintered body with high dimensional accuracy which could not be achieved by the conventional pressureless firing method which is generally used or the pressure firing method which is proposed thereafter with constant pressure. In addition, variations in firing shrinkage of the sintered body are small, and a sintered body free from warpage and peeling can be obtained. At the same time, it is possible to reduce the amount of residual carbon and realize a sintered body with few voids and excellent mechanical reliability. In particular, since the ceramic substrate obtained by the present invention can have extremely high dimensional accuracy of the component mounting surface, in addition to the LSI mounting substrate of a computer, a multilayer ceramic component used in various electronic devices such as high frequency electronic components, It can be widely used.

[Brief description of drawings]

FIG. 1 is a diagram showing a general relationship between a pressing force and a dimensional change (pressurized surface, XY direction) when a binder is removed while applying a constant pressing force to two opposing surfaces (XY directions) of a substrate. .

FIG. 2 is a diagram showing weight reduction and dimensional change behavior of a laminate (without pressurization of the laminate) due to removal of a binder in a binder removal step.

FIG. 3 is a diagram showing a relationship between a binder removal property and an open porosity in a molded body.

FIG. 4 is a diagram showing the relationship between the binder removal property and the open pore diameter in the molded body.

FIG. 5 is a diagram showing a configuration example of a ceramic sintered body manufacturing apparatus.

FIG. 6 is a flowchart showing an overall flow of processing of a control mechanism of the ceramic sintered body manufacturing apparatus.

FIG. 7 is a flowchart showing a flow of binder removal processing of a control mechanism of the ceramic sintered body manufacturing apparatus.

FIG. 8 is a flowchart showing a flow of a sintering process of a control mechanism of the ceramic sintered body manufacturing apparatus of the present invention.

[Explanation of symbols]

1 ... Furnace, 2 ... Multilayer ceramic laminate, 3 ... Heater, 4 ...
Voltage control unit, 5 ... Pressure applying unit, 6 ... Actuator, 7
... Control mechanism, 8 ... Holding plate, 9 ... Press board, 10 ... Heating and firing mechanism, 11 ... Atmosphere adjusting section, 20 ... Pressurizing mechanism.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shoichi Iwanaga 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Production Engineering Research Laboratory, Hitachi, Ltd. (72) Hideo Suzuki Inc. 1-7, Omika-cho, Hitachi-shi, Ibaraki No. 1 Hitachi Ltd. in Hitachi Research Laboratory (72) Inventor Masahide Okamoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi Ltd. Production Technology Research Laboratory (72) Inventor Masasaku Ishihara Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa 292 Hitachi, Ltd. Production Technology Research Laboratory (72) Inventor Shuichi Minagawa 1 Horiyamashita, Hadano City, Kanagawa Pref. Hitachi Ltd. General Computer Division (72) Inventor Takeshi Fujita 1 Horiyamashita, Hadano City, Kanagawa Prefecture Hitachi, Ltd. General-purpose computer division (56) References 63-35459 (JP, A) JP-A-5-8212 (JP, A) JP-A-2-305904 (JP, A) JP-A-2-5449 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) C04B 35/645, 35/638 H05K 3/46

Claims (6)

(57) [Claims] 1. A molded body manufacturing step of manufacturing a molded body containing ceramic powder and a binder, a binder removal step of heating the molded body to remove the binder, and heating the molded body to densify and sinter it. In a method for producing a ceramic sintered body, which comprises a sintering step for forming a body and a cooling step for cooling the sintered body in this order, in the sintering step, the temperature is low while applying pressure to the formed body. A method for producing a ceramic sintered body, which is a step of performing firing by changing from a temperature range to a high temperature range, wherein a pressure applied in the low temperature range is higher than a pressure applied in the high temperature range. 2. The molded body according to claim 1 , wherein the molded body is a laminated body formed by laminating a ceramic insulating layer containing at least one layer of ceramic powder and a binder, and a conductor layer made of at least one layer of conductor, The method for producing a ceramic sintered body, wherein the sintered body is a ceramic multilayer circuit board. 3. The method for producing a ceramic sintered body according to claim 1 , wherein the maximum temperature in the sintering step is in the range of 700 to 1700 ° C. 4. The pressure applied in the sintering step according to claim 1 , wherein the pressure is 1 to 20 kg.
/ Cm ^{2 A} method for producing a ceramic sintered body, characterized in that 5. The method of claim 1, the application of pressure in the sintering step is performed via a clamping plate sandwiching the shaped body, the clamping plate is dimensionally stable at the firing temperature of the shaped body, A method for producing a ceramic sintered body, which is made of a porous material having air permeability with a porosity of 50% or more. 6. A molded body producing step of producing a molded body containing ceramic powder and a binder, heating the molded body to remove the binder, and further heating the molded body to obtain a sintered body,
In the method for manufacturing a ceramic sintered body, which has a firing step of cooling the sintered body in this order, the firing step has a predetermined period of applying pressure to the molded body within the step, The method for producing a ceramic sintered body, wherein the pressure is set to be lower than that at the beginning of the period at the end of the period.