TWI388533B - Manufacturing method of ceramic molded body - Google Patents

Description

Method for manufacturing ceramic formed body

The present invention relates to a method for producing a ceramic formed body mainly composed of a ceramic substrate, and more particularly to a method of disposing a restraint layer on a fired body and suppressing shrinkage of the fired body in a planar direction while passing through one side. A method of producing a ceramic molded body such as a ceramic substrate produced by performing a step of calcination in a so-called restraint calcination process.

In the ceramic electronic component, for a ceramic substrate or the like which requires high planar dimensional accuracy, the calcination shrinkage in the planar direction in the calcination step and the unevenness of the shrinkage may have a large influence on the quality of the product.

Therefore, as a method of calcining the ceramic formed body while suppressing the shrinkage in the calcination step, a calcination method is proposed. For example, as shown in Fig. 4, ceramics are formed on both main faces of the ceramic formed body 51. In the state in which the hardly sinterable material such as alumina which is substantially non-sintered at the calcination temperature of the molded article 51 is calcined (constrained and calcined) in the state of the layers (constrained layers) 52a and 52b which are main components, it is possible to substantially Calcination is carried out in such a manner as to cause calcination shrinkage in the planar direction (see Patent Document 1).

Further, in the above-described conventional calcination method, in order to enhance the binding force exerted by the restraint layer, it is necessary to make the particle size of the hardly sinterable material small. However, since the base material layer and the restraint layer are firmly adhered after the particle diameter is made small, it is difficult to remove the restraint layer after firing, and there is a problem that the surface of the base material layer and the electrode are damaged. For example, when a multilayer ceramic substrate in which a ceramic layer or an electrode layer is thinned or multilayered is produced, there is a problem that cracks or electrode peeling occur on the substrate in the step of removing the restraint layer.

[Patent Document 1] Japanese Patent Laid-Open No. 4-243978

The present invention has been made in view of the above problems, and an object of the invention is to provide a method for producing a ceramic formed body which can be easily removed after the completion of the calcination step, and thus does not cause damage to the fired body in the step of removing the restraining layer. A ceramic molded body having high dimensional accuracy can be manufactured reliably and efficiently.

In order to solve the above problem, the method for producing a ceramic formed body according to claim 1 of the present invention, comprising the step of producing a laminated body, wherein the unfired laminated body is provided with a substrate layer and restrained In the layer, the base material layer contains a ceramic powder and a glass material, and the restraining layer contains: after being calcined in a low-oxygen environment, it does not burn out, but after the oxygen partial pressure is higher than the low-oxygen environment, the calcination is performed. a burn-off material that is not burned, and a ceramic powder that is not sintered at a sintering temperature of the base material layer; and the restraining layer is disposed in contact with a main surface of at least one of the base material layers; and the calcining step is performed on the unburned portion a step of calcining the substrate layer to sinter the substrate layer; and removing the restraint layer; the calcining step includes: a first calcination step of calcining in a state of having the restraint layer in the low oxygen atmosphere The base material layer is sintered; and the second calcination step is performed by calcining the oxygen partial pressure higher than the first calcination step to burn out the burn-in material constituting the restraint layer .

Further, in the method of producing a ceramic formed body according to claim 2, the ceramic formed body is a ceramic substrate.

Further, in the method of producing a ceramic formed body according to claim 3, in the first baking step, the glass material contained in the base material layer is impregnated to the restraint layer.

Further, in the method of producing a ceramic molded body according to claim 4, the particle size of the loss-generating material is larger than the particle diameter of the ceramic powder contained in the restraint layer.

Further, in the method of producing a ceramic formed body according to claim 5, the loss-generating material is carbon powder.

Further, in the method of producing a ceramic formed body according to claim 6, the ceramic powder contained in the restraint layer is made of the same material as the ceramic powder contained in the base material layer.

Further, the method for producing a ceramic formed body according to claim 7 includes a debonding step of removing the binder contained in the base material layer before the first baking step in the calcining step; the debonding agent The step is carried out in an oxygen-containing environment at a temperature at which the loss-generating material does not burn out.

Further, in the method of producing a ceramic formed body according to claim 8, in the step of producing the laminated body, the restraining layer is formed by causing at least the sheet containing the burn-in material and the ceramic powder and the base material layer The main faces of one side are arranged in contact with each other.

Further, in the method of producing a ceramic formed body according to claim 9, in the step of producing the laminated body, the restraining layer is formed by applying a paste containing the burn-in material and the ceramic powder to at least one of the base material layers. Formed on the main surface.

Further, in the method of producing a ceramic molded body according to claim 10, the base material layer has a plurality of layers, and the plurality of layers includes a plurality of layers containing the ceramic powder and the glass material.

Moreover, in the method of manufacturing a ceramic molded body according to claim 11, the base material layer has a wiring pattern on at least one of the main surfaces.

Further, the method of producing a ceramic formed body of claim 12 further comprising the step of mounting an electronic component on the outer surface of the substrate layer after the calcination step.

In the method for producing a ceramic formed article according to claim 1 of the present application, as the restraining layer, a restraining layer containing a component which does not burn out after calcination in a low-oxygen environment, but is in a partial pressure of oxygen is used. a burn-in material that burns out after calcination is higher than the low-oxygen environment; and a ceramic powder that is not sintered at a sintering temperature of the base material layer, so that the burn-in material does not burn out in the first calcination step. In a low-oxygen environment, the calcination is carried out, and after the base material layer is not shrunk in the planar direction and sintered, in the second calcination step, the oxygen partial pressure is higher than the first calcination step, and calcination is performed. When the loss-generating material constituting the restraint layer is burned out, micropores can be generated in the portion where the loss-loss material in the restraint layer has been burnt, and the restraint layer can be easily removed. As a result, it is possible to effectively remove the restraint layer by using a stable method which causes less damage such as cracks or defects in the fired body.

Therefore, according to the present invention, it is possible to manufacture a ceramic molded body having high dimensional accuracy with a high yield without a complicated manufacturing step.

Further, in the method for producing a ceramic molded body of the present invention, in the first baking step (constrained firing step), the restraining layer exhibits shrinkage of the base layer in the planar direction (direction parallel to the main surface). Binding power. Further, under the action of the restraining force, the sintering shrinkage of the base material layer in the planar direction is suppressed, and the fired body is substantially sintered and shrunk only in the thickness direction, so that the ceramic having high dimensional accuracy in the planar direction can be surely produced. Shaped body.

In the present invention, the low-oxygen environment refers to an environment in which the partial pressure of oxygen is relatively low compared with the atmosphere, and specifically, the partial pressure of oxygen at a normal pressure is not more than 10 ^-2 atm (that is, the environment). The environment in which the oxygen concentration is less than or equal to 1 vol%.

As a more preferable condition of the low-oxygen environment, for example, a condition that the partial pressure of oxygen at a normal pressure is 10 ^-3 to 10 ^-6 atm (oxygen concentration is 0.1 to 0.0001 vol%) is exemplified.

Further, the condition that the oxygen partial pressure in the second calcination step is higher than the first calcination step refers to an environment in which the partial pressure of oxygen can be burned and burned out, and specifically, oxygen is exemplified at normal pressure. The partial pressure is an environment of 10 ^-1 atm or more (that is, an oxygen concentration in the environment of 10 vol% or more).

Further, according to the second aspect of the invention, in the ceramic molded body, particularly when applied to a method for producing a ceramic substrate having a desired dimensional accuracy and shape accuracy in a planar direction, the present invention is effective in the use of the present invention. A ceramic substrate with high dimensional accuracy is produced.

Further, in the method of producing a ceramic molded body of claim 3, in the first baking step, the glass material contained in the base material layer penetrates into the restraint layer to form a permeation layer. Then, the restraining layer and the base material layer are firmly joined via the permeation layer, and the shrinkage of the base material layer in the first baking step in the planar direction is surely suppressed and prevented by the permeation layer.

Further, in order to obtain binding force more reliably, it is preferable that the glass material of the substrate layer is surely impregnated into the restraint layer. Further, it is preferable that the restraining layer is disposed so as to be in close contact with the base material layer.

Further, in the method for producing a ceramic formed body according to claim 4, the particle size of the loss-generating material is larger than the particle diameter of the ceramic powder contained in the restraining layer, whereby the restraining layer and only the ceramic powder and the binder are used. Compared with the previous case, the amount of the organic binder contained in the restraining layer can be reduced, and the debonding agent can be easily carried out.

Further, in the method for producing a ceramic formed body according to claim 5, the carbon powder used as the loss-generating material is not burned after being calcined in a low-oxygen partial pressure environment in the first calcination step, and does not shrink. Therefore, the function of suppressing the calcination shrinkage of the base material layer is fully exerted, and in the second calcination step, the calcination is carried out under the condition of high oxygen partial pressure, and then burned and burned out, so that the residual ceramic can be used as the main Micropores are formed in the restraint layer of the component, so that the restraint layer is easily collapsed and becomes easily removed. Further, by appropriately selecting the particle diameter of the carbon powder, when the particle diameter of the ceramic powder for the restraint layer is made small, the increase in the average specific surface area of the entire constituent material of the restraint layer can be suppressed, and the use can be reduced. The amount of organic binder.

Further, as the carbon powder, it is preferred to use a particle size of 1 to 5 μm. The reason for this is that when the particle diameter exceeds 5 μm, the binding force is insufficient, that is, when the particle diameter is 5 μm or less, a large binding force can be obtained, and by making the particle diameter 1 μm or more, the first constraint can be prevented. The loss of burning in the calcination step, on the other hand, ensures the ease of burning loss in the second calcination step.

In addition, in the case of the ceramic powder contained in the restraint layer, the ceramic powder contained in the base layer is made of the same material as the ceramic powder contained in the base material layer, whereby the glass is easily penetrated from the base material layer to the restraint layer, and the restraining force can be improved. .

Further, in the method for producing a ceramic formed body according to claim 7, the debonding step before the first calcination step is carried out in an oxygen-containing atmosphere and the calorie loss material is not burned out, so that the smoothing can be carried out smoothly The first baking step of removing the binder contained in the base material layer and then performing the restraint firing, and the second baking step of burning out the loss-generating material constituting the restraint layer are carried out.

In addition, the oxygen-containing environment at the time of the debonding step is exemplified by an atmosphere, an atmosphere in which an inert gas is introduced into the atmosphere, and the like. In general, when it is carried out under conditions of a high partial pressure of oxygen such as an atmospheric environment, the debonding agent can be efficiently carried out.

Further, in the present invention, as a method of forming the restraint layer, a method of preparing a sheet containing a loss-generating material and a ceramic powder in advance and contacting the main surface of at least one of the base material layers is exemplified. In the case of claim 9, a paste containing a loss-generating material and a ceramic powder is applied to at least one of the main surfaces of the base material layer. By using these methods, the restraining layer can be effectively disposed on at least one of the main surfaces of the base material layer.

Further, in order to obtain binding force as desired, it is preferable to adhere the restraint layer to the base material layer so that the glass material of the base material layer is surely impregnated into the restraint layer to form the impregnation layer. In addition, for example, when a plurality of sheets of the restraint layer are laminated to form a restraint layer, the sheet for the restraint layer of the plurality of sheets is pressed against the base layer to form a restraining layer. Or, when a binding layer is formed by applying a paste for a restraint layer, a fixing pressure is applied so that the adhesive layer paste is adhered to the base material layer while being applied.

Further, in the method for producing a ceramic formed body of the claim 10, the base material layer has a plurality of layers, whereby various ceramic molded bodies mainly composed of ceramic substrates having excellent planar shape accuracy can be efficiently produced.

Further, in the method for producing a ceramic formed body according to claim 11, the wiring pattern is formed on at least one of the main surfaces of the base material layer, and therefore, the ceramic molded body produced by the method is used, as in claim 12, The electronic component can be mounted on the base material layer which has been calcined by the calcination step, whereby the ceramic molded body mainly composed of the ceramic substrate having the structure in which the electronic component is mounted on the outer surface can be efficiently produced.

Hereinafter, the embodiments of the present invention will be described, and the features of the present invention will be described in more detail.

(1) Fabrication of a substrate layer containing ceramic powder and glass material

In order to form a base material layer which is a main part of the ceramic substrate, first, a binder, a dispersant, a plasticizer, an organic solvent, and the like are added to the mixed powder obtained by mixing the ceramic powder and the glass material, and these are added. Mixing, thereby preparing a ceramic slurry.

As the ceramic powder, various materials can be used. However, as an example of a preferable material, alumina (Al ₂ O ₃ ) powder is exemplified.

The glass material may initially contain glass powder or may be attached to the glassy material during the calcination step. Further, the glass material may be formed by crystallizing and crystallizing at least in the final stage of the calcination step. As the glass material, for example, a boric acid glass-based glass powder obtained by precipitating a crystal having a small dielectric loss such as bismuth silicate, magnesite or diopside can be used.

Then, the ceramic slurry is formed into a sheet shape by a doctor blade method or the like to form a green sheet (a ceramic green sheet for a substrate) 1a (FIG. 3) for a base material layer. Further, more specifically, CaO: 10 to 55 wt%, SiO ₂ : 45 to 70 wt%, Al ₂ 0 ₃ : 0 to 30 wt%, impurities: 0 to 10 wt%, B ₂ 0 ₃ as the glass powder. a glass powder having a composition of 5 to 20% by weight (average particle diameter of 1.5 μm) of 50 to 64% by weight, and 35 to 50% by weight of Al ₂ O ₃ powder (average particle diameter of 1.0 μm) as a ceramic powder. The mixture is mixed and dispersed in an organic vehicle composed of an organic solvent, a plasticizer or the like to prepare a slurry. Then, the slurry is formed into a sheet shape by a doctor blade molding method or a casting method to prepare a ceramic green sheet for a substrate. Further, the Al ₂ O ₃ powder as the ceramic powder may be one containing 0 to 10% by weight of impurities.

Further, the substrate (base material layer) is usually formed by laminating a plurality of ceramic green sheets, but may be composed of one ceramic green sheet. Further, the ceramic green sheet for a substrate is preferably a ceramic green sheet formed by the above-described sheet forming method, but may be an unsintered thick film printed layer formed by a thick film printing method. Further, in addition to the above insulator material, a ceramic material such as ferrite or a dielectric material such as barium titanate may be used as the ceramic powder.

Further, as the ceramic green sheet for a substrate, it is preferred to use a low-temperature sintered ceramic green sheet which is sintered at a temperature of 1050 ° C or lower. Further, it is preferable that the above glass powder has a softening point of 750 ° C or lower.

(2) Constraint

In the method for producing a ceramic formed body of the present invention, the restraining layer must have the following two properties:

(a) in the first firing step until the low-temperature sintered ceramic material constituting the base material layer is sintered, that is, in the first firing step in which the base layer is fired, the original function of the restraining layer for suppressing shrinkage of the base material layer is exhibited;

(b) The second calcination step in which the oxygen partial pressure is higher than the first calcination step is burned out in the second calcination step.

As a restraint layer having the above properties, the present invention is used in a low-oxygen environment, and does not burn out after calcination in a low-oxygen environment, but is burned out after calcination by making the oxygen partial pressure higher than the low-oxygen environment. The loss-in material and the ceramic powder which is not sintered at the sintering temperature of the substrate layer are main components.

As a preferable example of the restraint layer, a carbon powder is contained as the burn-in material, and an alumina powder is contained as a ceramic powder which is not sintered at a sintering temperature of the base material layer. Specifically, the mixed powder of the ceramic powder or the carbon powder such as alumina powder which is substantially not sintered at the firing temperature of the ceramic green sheet for the substrate is dispersed in an organic binder, an organic solvent, a plasticizer or the like. A slurry is prepared from the organic medium of the composition, and the obtained slurry is formed into a sheet shape to prepare a ceramic green sheet for a restraint layer, and if necessary, laminated to form a restraint layer.

The alumina powder is a powder which is easy to obtain a property and a stable property, and is not sintered at the sintering temperature of the base material layer, and is an ideal condition for the ceramic powder to exert a binding force. Further, the sintering temperature of the ceramic green sheets for the restraining layer using the alumina powder and the carbon powder is 1400 to 1600 ° C, and is substantially not sintered at the sintering temperature of the ceramic green sheets for the substrate. Further, the restraining layer may be formed of a ceramic green sheet of the above-mentioned restraint layer, or may be formed by laminating a plurality of restraint layers with ceramic green sheets.

As the ceramic powder, it is preferred to use an average particle diameter of 0.1 to 5.0 μm. When the average particle diameter of the ceramic powder is less than 0.1 μm, the glass contained in the surface layer of the ceramic layer as the base material layer is violently reacted in the calcination, and after the calcination, the ceramic layer and the restraint layer are adhered to each other to be calcined. After the restraint layer is not removed, or the organic component such as the binder in the sheet is hardly decomposed and scattered in the calcination step due to the small particle size, delamination may sometimes occur in the substrate layer. On the other hand, when the average particle diameter of the ceramic powder exceeds 5.0 μm, the suppression force of the firing shrinkage decreases, and the base material layer tends to excessively shrink or bend in the plane direction (xy direction).

Further, the ceramic powder constituting the restraint layer may be a ceramic powder which is substantially not sintered in the calcination step of the base material layer, and various ceramic powders such as zirconia or magnesia may be used in addition to the alumina. Among them, since there is a large amount of glass on the surface layer region of the substrate layer, the substrate layer and the restraint layer have a certain degree of affinity, and it is ideal on the boundary between the surface layer of the substrate layer and the restraint layer. The glass of the surface layer of the substrate layer is moderately wetted and restrained. Further, it is preferable to use a ceramic powder similar to the ceramic powder constituting the base material layer as the ceramic powder constituting the restraint layer.

Further, since the carbon powder as the loss-generating material is slow in combustion rate in the atmosphere and does not disappear in the calcination temperature range of the base material layer by the partial pressure of oxygen, it can be used as a non-shrinkage calcination. Constraint material. Therefore, in the calcination step, the carbon powder does not burn out during the period until the shrinkage of the base layer (that is, until the end of the first calcination step), but maintains the restraining function, and can be burned and disappeared after the shrinkage is completed. . Further, by burning and disappearing the carbon powder, micropores can be generated in the restraint layer containing the residual ceramic as a main component, and the restraint layer is liable to collapse and become easily removed. In addition, by appropriately selecting the particle diameter of the carbon powder, even when the particle diameter of the ceramic powder for the restraint layer is small, the increase in the average specific surface area can be suppressed, thereby suppressing the constituent material as the restraint layer. The increase in the average specific surface area of the whole.

Further, the carbon powder is used in a larger particle size than the ceramic powder such as alumina used in the restraining layer, and it is preferred to use a particle diameter of 2 to 20 μm. When the particle diameter of the carbon powder is smaller than the particle diameter of the ceramic powder and is less than 2 μm, compared with the previous case where the restraint layer is composed only of the ceramic powder and the binder (in the case where the carbon powder is not contained), The amount of the organic binder used is increased, the time required for the debonding step is lengthened, and the specific surface area of the carbon powder is increased, and the base material layer is burned and disappeared before the end of the shrinkage of the substrate layer, thereby causing the restraining force to decrease without good. In addition, when the particle diameter of the carbon powder exceeds 20 μm, the surface smoothness of the restraint layer is deteriorated, and the unevenness is transferred to the surface of the base material layer (substrate), which is not preferable. Further, the proportion of the carbon powder in the restraining layer is preferably in the range of 10 to 50 vol%. The reason for this is that if the proportion of the carbon powder is less than 10 vol%, the effect of easily removing the restraining layer is small, and if the proportion of the carbon powder is more than 50 vol%, the binding force in the firing step is lowered.

In other words, the basic binding force of the restraint layer is ensured by ceramic powder such as alumina powder having a small particle size, and the carbon powder is present as an inorganic material until the end of shrinkage of the base material layer. In the restraint layer, until the end of the contraction, the restraint layer is carefully maintained, so there is no decline in restraint. Further, since the carbon is burned out after the shrinkage is completed, micropores are formed in the restraining layer. Therefore, when the ceramic powder has a smaller particle diameter, the restrained layer after firing is also porous and easily removed. Further, by using a carbon powder having a larger particle diameter than the ceramic powder, the average specific surface area is made small, so that even when a ceramic powder having a small particle diameter is used, the amount of the organic binder to be used can be reduced. The debinding step is quickly terminated.

Moreover, the thickness of the restraining layer is preferably 25 to 500 μm. The reason for this is that if the thickness is less than 25 μm, the suppression force for firing shrinkage is small, and the substrate shrinks or bends more than necessary in the plane direction (xy direction), and if the thickness exceeds 500 μm, the ceramic green sheets for the substrate are used. The organic component such as the binder is difficult to be decomposed and scattered during calcination, which may cause problems such as delamination in the substrate.

(3) a conductor formed on a substrate layer and a conductive material used therefor

On the substrate layer, a via hole conductor, a via hole conductor, a conductor pattern as an outer conductor and an inner conductor, and the like are formed at the unfired stage, but as a conductive material used therefor, it is preferable to use a low resistance. A metal material (for example, Ag) of a hardly oxidizable material is mainly composed. However, as the conductive material, other materials may be used. For example, Ag-Pd, Au, Pt, or the like may also be used.

In addition, when the bonding strength with the ceramic is necessary, one or more kinds of additives such as Al ₂ O ₃ may be added to the conductive material. Further, an organic medium is added to the main component (conductive material) in a specific ratio, stirred and kneaded to prepare a conductive paste, and a via-hole conductor, a via-hole conductor, and an external portion can be formed using the conductive paste. Conductor patterns of conductors and internal conductors, etc. The type and ratio of the main component, the additive component, and the organic vehicle constituting the conductive paste are not particularly limited.

Further, the organic vehicle is a mixture of a binder resin and a solvent, and as the binder resin, for example, ethyl cellulose, acrylic resin, polyvinyl butyral, methacrylic resin or the like can be used. Further, as the solvent, for example, terpineol, dihydroterpineol, dihydroterpineol acetate, butyl carbitol, butyl carbitol acetate, alcohol or the like can be used. Further, various dispersants, plasticizers, active agents, and the like may be added as needed.

Further, in consideration of printability, the viscosity of the conductive paste is preferably 50 to 700 Pa‧s. Further, the conductor pattern on the surface of the base material layer also includes a portion of the through-conductor such as a via-hole conductor and a via-hole conductor for connecting the conductor patterns between the upper and lower layers to the surface. The through conductors can be formed by printing the paste into a through hole formed in a glass ceramic green sheet by a punching process or the like.

(4) Debonding step

The debonding step is usually carried out by heating from room temperature to the decomposition or combustion temperature of the binder in the atmosphere for a fixed period of time. For example, in the atmosphere, the temperature is raised from room temperature to 400 ° C and held for 60 minutes, whereby the debonding agent can be carried out.

Further, in the method for producing a ceramic formed article of the present invention, the debonding agent step is carried out in an environment having a high oxygen partial pressure in the atmosphere, which is preferable in terms of achieving high efficiency. However, the debonding agent may be carried out under conditions in which the oxygen partial pressure is lower than the atmosphere, and depending on the case, it may be carried out in a low oxygen environment in which the oxygen partial pressure phase is very low.

(5) Calcination conditions

(a) The first calcination step is carried out by introducing nitrogen into the debonding step and heating the substrate layer to a temperature of, for example, 400 ° C to 950 ° C. In the present invention, the low-oxygen environment in the first calcination step refers to an environment in which the oxygen partial pressure is lower than the atmosphere, but particularly in the case where the partial pressure of oxygen is 10 ^-3 to 10 ^-6 atm, the carbon in the restraint layer It is preferred that the burn-in material such as powder does not lose weight and can reliably bind the substrate layer.

(b) The second calcination step is carried out under conditions in which the oxygen partial pressure is higher than the first calcination step, and the loss-in material in the restraint layer is burned out, thereby improving the removability of the subsequent restraint layer.

For example, after the completion of the first calcination step, the atmosphere is introduced, and under normal pressure, the oxygen partial pressure is maintained at 0.21 atm and 950 ° C for 10 minutes to burn off the carbon in the restraint layer.

Further, the first calcination step and the second calcination step may be carried out at the same calcination temperature as described above, but the temperatures in the first calcination step and the second calcination step may be different. Further, the first calcination step and the second calcination step may be continuously performed, or may be temporarily taken out from the furnace after the first calcination step, and then placed in the furnace again to carry out the second calcination step.

The embodiments of the present invention are shown below to explain the features of the present invention in more detail.

[Example 1]

1 is a view showing a ceramic substrate (multilayer ceramic substrate) produced by a method for producing a ceramic substrate according to an embodiment (Example 1) of the present invention, and FIG. 2 is a view showing a mounting member mounted on the ceramic substrate of FIG. FIG. 3 is a view showing an unfired laminated body having a restraining layer produced in the step of manufacturing the ceramic substrate of FIGS. 1 and 2.

The ceramic substrate A shown in FIG. 1 includes an insulating ceramic layer 1 obtained by firing a low-temperature sintered ceramic raw material composition containing a ceramic powder and a glass material, and a conductor portion 2 disposed on the insulating ceramic layer 1. In addition, the ceramic substrate A of the first embodiment is a multilayer substrate having a plurality of layers in which a plurality of insulating ceramic layers 1 are laminated.

As the low-temperature sintered ceramic composition constituting the insulating ceramic layer 1, a low-temperature sintered ceramic composition obtained by blending an alumina-based ceramic powder and a borosilicate glass-based glass powder is used.

Further, the conductor portion 2 is composed of a surface conductor (outer conductor) 21 on the surface of the ceramic substrate A, and an interlayer conductor (internal conductor) disposed between the plurality of insulating ceramic layers 1, 1 joined to each other. 22, and a via conductor 23 connecting the interlayer conductors 22 to each other or the surface conductor 21 and the interlayer conductor 22.

The surface conductor 21 and the interlayer conductor 22 are formed by firing an outer conductor film and an inner conductor film in which a conductive paste (for example, a silver-based conductive paste) is formed by printing. Moreover, the via-hole conductor 23 is formed, for example, by filling a through-hole with a conductive paste and a conductor powder, and baking.

In addition, the ceramic substrate (multilayer ceramic substrate) B on which the electronic component of FIG. 2 is mounted is formed by mounting the electronic components 3a and 3b such as a semiconductor element and a chip capacitor on the ceramic substrate (multilayer ceramic substrate) A of FIG. .

Next, a method of manufacturing the multilayer ceramic substrates A and B will be described.

Hereinafter, the description will be made with reference to FIGS. 1 to 3.

(1) First, a binder, a dispersant, a plasticizer, an organic solvent, and the like are added to a mixed powder obtained by mixing ceramic powder and a glass material, and these are mixed to prepare a ceramic slurry.

(2) Next, the ceramic slurry is formed into a sheet shape by a doctor blade method or the like to prepare a ceramic green sheet 1a for a substrate (Fig. 3). Again, here,

(a) 45 wt% of a glass powder having a composition of CaO: 43 wt%, SiO ₂ : 44 wt%, Al ₂ 0 ₃ : 7 wt%, and B ₂ 0 ₃ : 6 wt% as a glass powder, and

(b) Al ₂ 0 ₃ powder as a ceramic powder 55 wt%

The mixing is carried out, and the mixture is dispersed in an organic vehicle composed of an organic solvent, a plasticizer or the like to prepare a slurry. Then, the slurry is formed into a sheet shape by a doctor blade molding method or a casting method to prepare a ceramic green sheet for a substrate. Further, the ceramic green sheet for the substrate has a sintering temperature of 1050 ° C or lower.

(3) Next, on the obtained ceramic green sheet 1a for a substrate, a through hole 12 (FIG. 3) for forming a via conductor is formed as needed, and a conductive paste is filled in the through hole 12 Alternatively, the unfired via-hole conductor 23a (FIG. 3) is formed by the conductor powder (further, in the first embodiment, the through-hole 12 is filled with a conductive paste containing Ag as a conductive component).

(4) Further, on the ceramic green sheet 1a for a substrate, an unsintered outer conductor 21a and an inner conductor 22a (see Fig. 3) are formed, for example, by printing a silver-based conductive paste.

(5) Further, ceramic green sheets for the restraint layer for forming the restraint layer were produced in the following order.

First, a ceramic powder (aluminum powder in the first embodiment) and a mixed powder of carbon powder which are substantially not sintered at the calcination temperature of the ceramic green sheet for the substrate are dispersed in an organic binder or an organic solvent. An organic vehicle composed of a plasticizer or the like to prepare a slurry.

Then, the obtained slurry was formed into a sheet shape to prepare a ceramic green sheet for a restraint layer.

Further, in the first embodiment, the ratio of the carbon powder in the slurry was set to 20 vol%. Further, as the ceramic powder, alumina powder having an average particle diameter of 1 μm was used, and as the carbon powder, carbon powder having an average particle diameter of 3 μm was used. The sintering temperature of the ceramic green sheet for the restraint layer is 1400 to 1600 ° C, which is substantially not sintered at the sintering temperature of the ceramic green sheet for the substrate. Further, in the first embodiment, the thickness of the restraint ceramic green sheet was set to 300 μm in order to ensure sufficient binding force.

(6) Next, as shown in FIG. 3, a plurality of substrate ceramic green sheets 1a are laminated in a specific order, and the restraint layer 31 is disposed and laminated to have a plurality of layer structures formed by laminating the ceramic green sheets 1a for the substrate. The two main surfaces of the base material layer (unfired ceramic substrate) A' are pressed and pressure-bonded by a method such as hydrostatic pressing, for example, at a pressure of 5 to 200 MPa. Thereby, an unfired laminated body 32 having a structure in which the restraining layer 31 is disposed is formed on the upper and lower sides of the base material layer (unfired ceramic substrate) A' (see FIG. 3). In the first embodiment, the thickness of the base material layer (unfired ceramic substrate) A' was 300 μm, and the thickness of the restraint layer 31 was 300 μm.

Further, the unfired laminated body 32 may be cut into an appropriate size as needed. Further, in the first embodiment, a plurality of substrate ceramic green sheets 1a are laminated to form a base layer A' having a plurality of layers, but the number of the ceramic green sheets 1a for the substrate may be one by one. A base material layer of a layer structure, and a single-plate type ceramic substrate is produced.

Further, in the first embodiment, the restraining layer 31 is disposed on the upper and lower sides of the base material layer (unfired ceramic substrate) A', but the restraining layer 31 may be disposed on the base material layer ( On the main surface of only one of the unfired ceramic substrates) A'.

Further, the restraining layer 31 can be formed by laminating a plurality of restraint layers with a ceramic green sheet, and can also be formed by using a ceramic green sheet with a restraining layer.

(7) Next, the unfired laminated body 32 is heat-treated at a low temperature degreasing temperature (for example, a temperature of about 400 ° C) in the air to remove an organic substance such as a binder.

Thereafter, the base material layer (unfired ceramic substrate) A' is sintered, but the ceramic powder constituting the restraint layer 31 is not sintered, and the burn-in material constituting the restraint layer 31 is not burned, that is, the implementation In Example 1, the temperature was raised to 850 to 950 ° C in a low-oxygen atmosphere having an oxygen concentration of 1 vol% or less, and calcination was carried out to sinter the base material layer (unfired ceramic substrate) A' (first baking step).

At this time, the ceramic powder constituting the restraint layer 3 is not sintered, and the carbon powder remains without being burned out. Therefore, the restraint layer 31 sufficiently functions to suppress shrinkage of the base material layer A' in the planar direction.

(8) Thereafter, the oxygen partial pressure is higher than the first calcination step (in the first embodiment, the oxygen concentration is 10 vol%), and calcination is carried out (second calcination step) to form a constrained layer 31. Loss of material carbon powder burned out. As a result, micropores are formed in the portion where the carbon powder is lost in the restraint layer, so that the restraint layer is porous and easily removed.

(9) Then, the ceramic substrate A having the configuration shown in Fig. 1 is obtained by removing the confinement layer 31 in the porous state.

Further, according to the method of the first embodiment, in the composite laminate after the calcination, the restraint layer is substantially not sintered, and the carbon powder contained before the calcination is burned out to be in a porous state, so that it has been used in the past. The discharge pressure of the ceramic powder and the binder which are not contained in the burn-off material (the carbon powder in the first embodiment) is lower than that in the case of using the blasting method or the wet blasting method, for example, when the blasting method or the wet blasting method is used. And the time required to remove the restraint layer becomes shorter. As a result, the restraint layer can be removed without impairing the smoothness of the substrate surface and the electrode surface, so that a ceramic molded body having high dimensional accuracy can be produced with a good yield.

According to the first embodiment, it is confirmed that when the restraint layer for shrinkage suppression is formed by using the ceramic powder having high binding force (the alumina powder in the first embodiment), the binding force can be ensured by blending the carbon powder. Ensure ease of removal of the restraint layer after calcination.

Further, as a side effect, it is possible to obtain an effect of coloring the green sheets for the restraint layer by mixing the carbon powder, thereby easily distinguishing them from the ceramic green sheets for the substrate, thereby preventing an error in which the two are mistaken, thereby improving Reliability of the manufacturing steps. Further, in general, when the ceramic green sheet is colored, a transition metal element is often used to diffuse the base material layer to color the base material. However, according to the present invention, the base material layer is not colored, so that the appearance quality is not deteriorated. .

In the first embodiment, the case where the ceramic substrate is used as the ceramic formed body has been described as an example. However, the present invention is not limited to the ceramic substrate, and may be applied to ceramic coil parts, ceramic LC composite parts, and the like. A method of manufacturing various ceramic molded bodies mainly composed of ceramic electronic components.

Furthermore, the present invention is not limited to the above-described first embodiment, and the specific types and blending ratios of the ceramic powder and the glass material constituting the base material layer, the burn-in material constituting the restraint layer, and the ceramic powder are specifically The type, the specific conditions in the first and second calcination steps, the treatment conditions in the debonding step, and the like can be variously applied and modified within the scope of the invention.

[Industrial availability]

As described above, according to the present invention, the shrinkage suppressing effect in the calcination step can be sufficiently ensured, and the restraint layer can be easily removed after the completion of the calcination step, so that the ceramic molded body is not damaged in the step of removing the restraint layer, and it is possible to confirm Moreover, a ceramic molded body having high dimensional accuracy is efficiently produced. Therefore, the present invention can be widely utilized in the field of manufacturing ceramic shaped bodies produced by the calcination step.

1. . . Insulating ceramic layer

1a. . . Ceramic tile for substrate

2. . . Conductor

3a, 3b. . . Installing electronic parts

12. . . Through hole

twenty one. . . Surface conductor (outer conductor)

21a. . . Unsintered outer conductor

twenty two. . . Interlayer conductor (internal conductor)

22a. . . Unsintered internal conductor

twenty three. . . Through hole conductor

23a. . . Unsintered via conductor

31. . . Constraint

32. . . Unburned laminate

A. . . Ceramic substrate (multilayer ceramic substrate)

A'. . . Substrate layer (unfired ceramic substrate)

B. . . Ceramic substrate (multilayer ceramic substrate)

Fig. 1 is a view showing a ceramic substrate (multilayer ceramic substrate) produced by a method for producing a ceramic formed body (ceramic substrate) according to an embodiment (Example 1) of the present invention.

Fig. 2 is a view showing a state in which mounted components are mounted on the ceramic substrate of Fig. 1;

Fig. 3 is a view showing an unfired laminated body having a restraining layer produced in the step of manufacturing the ceramic substrate of Figs. 1 and 2;

Fig. 4 is a view showing a method of restraining and calcining a ceramic formed body using a restraint layer containing a hardly sinterable material as a main component.

1a. . . Ceramic tile for substrate

12. . . Through hole

21a. . . Unsintered outer conductor

22a. . . Unsintered internal conductor

23a. . . Unsintered via conductor

31. . . Constraint

32. . . Unburned laminate

A'. . . Substrate layer (unfired ceramic substrate)

Claims (13)

A method for producing a ceramic formed body, comprising: a layered body producing step of producing an unfired laminated body, wherein the unfired laminated body comprises a base material layer and a restraining layer, and the base material layer contains ceramic powder and In the glass material, the restraining layer contains a burn-in material that is not burned out after being calcined in a low-oxygen environment, but is burned out after being calcined by making the oxygen partial pressure higher than the above-described low-oxygen environment, and a ceramic powder which is not sintered at a sintering temperature of the base material layer; and the restraining layer is disposed in contact with at least one of the main surfaces of the base material layer; and in the calcining step, the unfired laminated body is calcined to make the substrate a layer sintering process; and a step of removing the above-mentioned restraint layer; the calcination step includes: a first calcination step of calcining the base material layer in a state of having the restraint layer in the low oxygen atmosphere; and second calcination The step of calcining the oxygen partial pressure is higher than the first calcination step to burn out the burn-in material constituting the restraint layer. The method of producing a ceramic formed body according to claim 1, wherein the ceramic formed body is a ceramic substrate. The method of producing a ceramic formed body according to claim 1, wherein in the first baking step, the glass material contained in the base material layer is impregnated to the restraint layer. A method of producing a ceramic formed body according to claim 2, wherein the first calcination is performed In the baking step, the glass material contained in the base material layer is impregnated into the restraint layer to be calcined. The method for producing a ceramic formed body according to any one of claims 1 to 4, wherein the particle size of the burn-in material is larger than a particle diameter of the ceramic powder contained in the restraint layer. The method for producing a ceramic formed body according to any one of claims 1 to 4, wherein the burn-in material is carbon powder. The method for producing a ceramic molded body according to any one of claims 1 to 4, wherein the ceramic powder contained in the restraining layer is made of the same material as the ceramic powder contained in the base material layer. The method for producing a ceramic formed body according to any one of claims 1 to 4, wherein the base material layer contains a binder, and includes a debonding agent step before the first calcination step in the calcining step, The binder is removed in the base layer; the debonding step is carried out in an oxygen-containing atmosphere and the burn-in material is not burned out. The method for producing a ceramic formed body according to any one of claims 1 to 4, wherein in the step of producing the laminated body, the restraining layer is formed by using a sheet containing the burn-in material and the ceramic powder and the base The main surface of at least one of the material layers is arranged to be in contact with each other. The method for producing a ceramic formed article according to any one of claims 1 to 4, wherein in the step of producing the laminated body, the restraining layer is formed by applying a paste containing the burn-in material and the ceramic powder to the substrate It is formed on the main surface of at least one of the layers. The method for producing a ceramic formed body according to any one of claims 1 to 4, wherein the base material layer has a plurality of layers having a plurality of layers containing the ceramic powder and the glass material. The method for producing a ceramic molded body according to any one of claims 1 to 4, wherein the base material layer has a wiring pattern on at least one of the main surfaces. The method of producing a ceramic formed body according to any one of claims 1 to 4, further comprising the step of mounting an electronic component on a surface of the substrate layer after the calcination step.