JP4885749B2 - Manufacturing method of ceramic laminated substrate - Google Patents

Description

  The present invention relates to a method for producing a ceramic laminated substrate, and more specifically, can be produced by subjecting a ceramic laminated substrate having a high density and a small in-plane positional deviation due to firing to restrained firing at a low firing temperature. The present invention relates to a method for manufacturing a ceramic laminated substrate.

  An LTCC substrate (Low-Temperature Co-fired Ceramics) used for dielectric multilayer filters, multilayer wiring boards, dielectric antennas, dielectric couplers, dielectric composite modules, and the like includes a dielectric layer mainly composed of glass and ceramics, A ceramic laminated substrate having a laminated structure composed of internal conductor layers, generally formed by laminating and firing a ceramic green sheet having conductors disposed thereon. However, the above-described manufacturing method has a problem in that the XY plane (a plane parallel to the surface of the LTCC substrate) is distorted due to firing shrinkage, and the arrangement (pattern) of conductors and the like varies (the surface position accuracy is low). there were. And this variation becomes more conspicuous as the size of the LTCC substrate becomes larger. Therefore, there is a problem that it is difficult to increase the size of a sheet that can be obtained in large numbers.

  As one of the methods for suppressing the variation, there is a constrained firing method (see, for example, Patent Documents 1 to 4). In this method, a green sheet laminate having a conductive layer inside and mainly composed of glass ceramics is sandwiched and fired by a ceramic constraining layer that does not shrink at the sintering temperature of the substrate, thereby reducing shrinkage in the XY plane. This is a so-called non-shrinkage firing method in which a substrate can be produced while suppressing. In this method, when the densification is advanced until the density becomes close to 100%, there is a problem that the constraining layer is peeled off at the outer edge portion of the substrate surface and the constrained firing is not partially performed.

Recently, in order to achieve downsizing of electronic components such as filters, the main component of the green sheet laminate may be ceramics having a high dielectric constant. Normally, when ceramics are sintered, the whole ceramics shrink (fire shrinkage) while the pores in the inside decrease (dense as the densification proceeds), but in the XY plane When the shrinkage is suppressed and the firing shrinks only in the Z direction, the ceramic as a whole is in a state where it is difficult to shrink, and therefore firing is also difficult to proceed. When constrained firing is applied to such a material, densification of the green sheet laminate is insufficient, and in particular, in the surface layer portion of the green sheet laminate that is in close contact with the constraining layer, densification tends to be insufficient. . Although the surface layer portion becomes denser by firing at a higher temperature, raising the firing temperature until the entire laminate has a uniform dense structure causes problems such as the diffusion of the material forming the internal conductor layer. . In this case, there is a problem that the material of the inner conductor layer is limited due to the problem of the heat resistant temperature of the inner conductor layer.
Japanese Patent No. 2554415 Japanese Patent No. 2617643 JP 2001-210951 A JP 2004-165295 A

  The constrained layer peeling occurs in the constrained firing for the following reason. In constrained firing, the shrinkage in the XY plane of the dielectric layer (substrate) is constrained by the ceramic constraining layer, so that the firing shrinkage is limited in the Z direction (thickness direction of the substrate). Since the ceramic constraining layer constrains the dielectric layer (substrate) that is to shrink in the XY plane, shear stress is generated at the interface between the ceramic constraining layer and the dielectric layer (substrate). For this reason, in densification firing, if densification proceeds until the density becomes close to 100%, a large shear stress is applied to the interface between the ceramic constraining layer and the substrate. In particular, since there is no constraining layer on the side surface of the substrate, contraction in the XY plane is likely to occur compared to the central portion, and the shearing force acts greatly at the outer edge portion of the substrate surface that constrains it, resulting in constraining layer peeling. It is.

  Also, when the main component of the green sheet laminate is a ceramic with a high dielectric constant, the surface layer portion of the green sheet laminate is insufficiently densified because the ceramic with a high dielectric constant has a viscosity during firing. Since the flow hardly occurs, when the shrinkage in the XY plane is suppressed and contracts in the Z direction, the vicinity of the interface with the ceramic constraining layer that suppresses the shrinkage most in the XY plane (the surface layer portion of the green sheet laminate) is This is because it is not sufficiently fired and shrunk.

  The present invention has been made in view of the above-described problems, and can be manufactured by subjecting a ceramic laminated substrate having a high density and a small in-plane positional shift accompanying firing to a low firing temperature. A method for producing a ceramic laminated substrate is provided.

  In order to achieve the above object, the present invention provides the following method for producing a ceramic laminated substrate.

[1] Forming a plurality of dielectric green sheets containing ceramics and glass, disposing a conductor on at least one surface of the at least one dielectric green sheet, and laminating the plurality of dielectric green sheets. And forming a composite body by disposing a ceramic constrained layer that is not sintered at the firing temperature of the multilayer body on both surfaces of the multilayer body, and firing the composite body (first firing). The first firing is completed before the densification of the laminate is completed, and the laminate in the composite is used as a pre-densification laminate, and the ceramic constraining layer is removed from the composite. The resulting pre-densified laminate is removed and fired at a temperature (second firing temperature) equal to or lower than the firing temperature (first firing temperature) in the first firing (second firing), Density of the laminate before densification Method of manufacturing a ceramic multilayer substrate to the ceramic multilayer substrate to complete the reduction.

[2] The method for producing a ceramic laminated substrate according to [1], wherein the density of the laminate before densification is 85 to 95% by volume.

[3] The method for producing a ceramic laminated substrate according to [1] or [2], wherein a temperature difference between the first firing temperature and the second firing temperature is 50 ° C. or less.

[4] The production of the ceramic laminated substrate according to any one of [1] to [3], wherein a difference between the density of the pre-densified laminate and the density of the ceramic laminated substrate is 2 to 12% by volume. Method.

[5] The method for producing a ceramic laminated substrate according to any one of [1] to [4], wherein the ceramic content of the dielectric green sheet is 90% by mass or more.

[6] The ceramic laminated substrate according to any one of [1] to [5], wherein at least one of the plurality of dielectric green sheets is formed of a material different from that of the other dielectric green sheets. Production method.

[7] The method for producing a ceramic multilayer substrate according to any one of the dielectric constant of the ceramic multilayer substrate comprising a layer of 2 5-1 5 0 [1] to [6].

  According to the method for producing a ceramic laminated substrate of the present invention, in the first firing, the laminated body constituting the composite is used as a pre-densified laminated body before completion of densification, and then the ceramic constraining layer is removed, In the firing of, in order to complete the densification of the laminate before densification to obtain a ceramic laminate substrate, by forming a composite (by sandwiching the laminate with a ceramic constraining layer) and forming the laminate before densification A ceramic multilayer substrate with high surface position accuracy can be manufactured, and a ceramic multilayer substrate with high density can be manufactured at a lower firing temperature than removing the ceramic constraining layer in the second firing for the final densification completion. .

  Hereinafter, the best mode for carrying out the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the following embodiment and does not depart from the spirit of the present invention. Therefore, it should be understood that design changes, improvements, and the like can be made as appropriate based on ordinary knowledge of those skilled in the art.

  FIG. 1 is a schematic diagram for explaining one embodiment of a method for producing a ceramic laminated substrate of the present invention. FIG. 1 (a) shows a laminate and a ceramic constrained layer, and FIG. The composite body at the time of the 1st baking is shown, and FIG.1 (c) shows the laminated body (ceramics laminated substrate) before densification at the time of the 2nd baking. As shown in FIGS. 1 (a) to 1 (c), a method for manufacturing a ceramic laminated substrate according to the present embodiment forms a plurality of dielectric green sheets 1 containing ceramics and glass, and at least one dielectric. A conductor 2 is disposed on at least one surface of the green body 1 and a plurality of dielectric green sheets 1 are laminated to form a laminate 3, and the firing temperature of the laminate 3 is formed on both sides of the laminate 3. Then, the ceramic constrained layer 4 that is not sintered is disposed to form the composite 5, the firing of the composite 5 (first firing) is started, and the first firing is completed before the densification of the laminate 3 is completed. And the laminate 3 in the composite 5 is used as the pre-densified laminate 6, the ceramic constraining layer 4 is removed from the composite 5 and the pre-densified laminate 6 is taken out, and the resulting pre-densified laminate 6 is a firing temperature in the first firing (first firing Forming temperature) below the temperature (by firing at a second baking temperature) (second baking), in which to complete the densification front densification of the laminate 6 and the ceramic multilayer substrate 7.

  As described above, in the method for manufacturing a ceramic laminated substrate according to the present embodiment, the composite body 5 having the structure in which the multilayer body 3 is sandwiched between the ceramic constraining layers 4 is formed, and the composite body 5 is fired to form the laminated body before densification. Therefore, it is possible to suppress the generation of distortion on the XY plane (surface parallel to the surface of the ceramic multilayer substrate) as in the case where the densification is completed in an unconstrained state. Can be manufactured. Here, the surface position accuracy refers to a variation in dimensional change due to firing at an arbitrary distance between two points in the substrate surface. Further, by removing the ceramic constraining layer during the second firing for completing the densification, it is possible to advance the densification that was incomplete in the first firing at a low firing temperature. A ceramic laminated substrate with a high density can be manufactured while maintaining the above.

  In the method for manufacturing a ceramic multilayer substrate according to this embodiment, first, a plurality of dielectric green sheets 1 containing ceramics and glass are formed. The method for producing dielectric green sheet 1 is not particularly limited, and can be produced by a known method for producing dielectric green sheet. For example, a dielectric material, glass, an organic material such as a binder, a dispersion medium such as an organic solvent, etc. are mixed, and a slurry is formed into a dielectric green sheet by a doctor blade method or the like. . The thickness of the dielectric green sheet 1 is preferably 30 to 150 μm, and more preferably 40 to 80 μm. When the thickness is smaller than 30 μm, the diffusion of the conductor element (for example, Ag) at the time of co-firing with the conductor cannot be ignored and the quality characteristics may be deteriorated. When the thickness is larger than 150 μm, the device size may be increased. The size of the dielectric green sheet can be appropriately determined according to the application.

The dielectric material can be appropriately determined according to the application, but preferably contains 90% by mass or more of ceramics and 10% by mass or less of glass components. Further, it is more preferable that the ceramic content is 95 to 98% by mass and the glass component is 2 to 5% by mass. The glass component functions as a sintering aid. When the glass component is more than 10% by mass, the dielectric constant and unloaded Q of the ceramic laminated substrate are lowered, which is not preferable. The glass component is preferably contained in an amount of 2% by mass or more from the viewpoint of promoting the sintering. Examples of the dielectric material include a BaO—TiO ₂ —Re ₂ O ₃ system composition (Re: rare earth component) with some glass powder added, and a BaO—TiO ₂ —ZnO system composition containing a little glass. Components and / or glass powder added, BaO—Al ₂ O ₃ —SiO ₂ —Bi ₂ O ₃ system composition with some glass forming components and / or glass powder added and zinc oxide, bismuth oxide as required Or containing copper oxide, MgO—CaO—TiO ₂ —ZnO—Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ based composition, BaO—TiO ₂ based composition with some glass forming components and / or glass powder those obtained by _adding, that the addition of some of the glass powder in _{BaO-TiO 2 -Nd 2 O 3} -Bi 2 O 3 based _{compositions, BaO-TiO 2 -ZnO-MnO} -Al 2 O 3 Those obtained by adding a small amount of glass-forming components and / or glass powder in the _composition, having composition of _{(Ba 1-a Sr a)} 6 Nd 8 Yi 18 O 54 (a 0.20 or more, 0.50 or less), Examples thereof include those having a composition of Ba ₄ Sr ₂ (Nd _1-b Y _b ) ₈ Ti ₁₈ O ₅₄ (b is 0 or more and 0.40 or less). Here, the glass forming component and / or the glass powder is a glass component. Among these, a structure in which a layer having a high dielectric constant composition and a layer having a low dielectric constant composition are laminated (a laminated body in which a high dielectric constant material and a low dielectric constant material are combined) is preferable (Reference: JP 2001-267805 (Nippon Isogo)), for example, a composition having a high dielectric constant (relative dielectric constant of about 85) has a BaO—TiO ₂ —Nd ₂ O ₃ —Bi ₂ O ₃ composition and ZnO—SiO ₂ —B _2. the O ₃ based glass composition obtained by blending 2-5 wt% is preferred. As a composition having a low dielectric constant (relative dielectric constant of about 7), ₂ to 5 wt% of ZnO—SiO ₂ —B ₂ O ₃ glass is added to the BaO—Al ₂ O ₃ —SiO ₂ —Bi ₂ O ₃ composition. The composition is preferred.

  At least one of the plurality of dielectric green sheets 1 may be formed of a material (dielectric material) different from the other dielectric green sheets 1. When the materials (dielectric raw materials) constituting each dielectric green sheet 1 are different, the combination of the materials can be appropriately determined depending on the application.

  Next, the conductor 2 is disposed on at least one surface of at least one of the obtained dielectric green sheets 1. The conductor 2 may be disposed on both surfaces of the dielectric green sheet 1, or the conductor 2 may be disposed on all the dielectric green sheets 1. The arrangement method of the conductor 2 is not particularly limited, and examples thereof include a method of printing a conductor material on the surface of the dielectric green sheet. The formation pattern of the conductor 2 is not particularly limited, and can be appropriately determined according to the application. For example, when the ceramic laminated substrate to be produced is used as an LTCC substrate used for a high frequency filter or the like, the respective conductors 2 are arranged so as to form a filter, a diplexer, a resonator, a capacitor, etc. It is preferable to form the portion to be formed of the conductor 2. Examples of the conductor material include metals and cermets, and silver (Ag), copper (Cu), and the like are particularly preferable. In addition, Pd, Ag, Au, Ru, Rh, Re, Os, Ir, Pt, and Pd, Ag, Au, Ru, Rh, and the like are added to these materials for the purpose of improving heat resistance and suppressing component diffusion into the dielectric layer. Ti, Cr, Mn, Fe, Co, Ni, Zn, Zr, Nb, Mo, Ta, W, or the like may be blended. In the case of forming by printing or the like, composite particles obtained by coating a metal powder with an oxide or the like may be used. As a result, a good bonding state can be obtained by combining the firing shrinkage behavior of the dielectric and the conductor.

  Next, a plurality of dielectric green sheets 1 including the dielectric green sheet 1 provided with the conductor 2 are laminated to form a laminate 3, and the firing temperature of the laminate 3 is formed on both sides of the laminate 3. Then, the ceramic constraining layers 4 and 4 that are not sintered are disposed to form the composite 5. Here, as shown in FIG. 1 (a), the laminate 3 may be prepared first, and then the ceramic constraining layers 4 and 4 may be disposed (laminated), or the dielectric green sheet 1 and the ceramic constraining layer may be provided. 4 and 4 may be laminated all at once, and the composite 5 may be produced simultaneously with the production of the laminate 3. When laminating the dielectric green sheets 1, it is preferable to press and apply pressure. Uniaxial pressurization, hydrostatic pressure pressurization, etc. can be used for pressurization. Similarly, when all of the dielectric green sheet 1 and the ceramic constraining layers 4 and 4 are laminated at a time, it is also preferable to apply pressure to the entire laminated body and press-bond it.

  The firing temperature of the laminate 3 means a temperature when firing the composite 5 in the next step (first firing temperature). The ceramic constituting the ceramic constraining layer 4 can be appropriately determined depending on the dielectric material constituting the laminate 3, but any material that does not sinter at the sintering temperature of the laminate 3 may be selected. For example, alumina, magnesia, spinel and the like can be mentioned. The thickness of the ceramic constraining layer 4 is not particularly limited, but is preferably 50 to 500 μm, and more preferably 100 to 400 μm.

  As a method for producing the ceramic constraining layer 4 (constraint layer sheet), it is preferable to produce a constraining layer sheet in the same manner as the dielectric green sheet 1 is produced. At this time, it is preferable to use materials such as alumina, magnesia, and spinel in place of the dielectric material used for the production of the dielectric green sheet 1. A material close to the thermal expansion curve of the dielectric material is preferred.

  Next, firing of the composite 5 (first firing) is started, the first firing is finished before the densification of the laminate 3 is completed, and the laminate 3 in the composite 5 is before densification. Let it be the laminated body 6. In this way, since firing is performed with the ceramic constraining layers 4 disposed on both surfaces of the laminate 3 (constrained state), the pre-densification laminate 6 with small surface shrinkage and high surface position accuracy is obtained. Can do. This is because in the first firing, the ceramic constrained layer 4 does not sinter and does not shrink, and thus functions to suppress the shrinkage of the laminated body 3 sandwiched therebetween. The density of the pre-densified laminate 6 is preferably 85 to 95% by volume, and more preferably 90 to 94% by volume. Generation of constrained layer peeling that occurs when densification is completed in a constrained state by setting the density of the layered product 6 before densification within such a range without completing densification in the first firing. Can be prevented. If the density is lower than 85% by volume, the shrinkage in the XY plane may increase during the second baking, and the surface position accuracy may decrease. If it is higher than 96% by volume, the constrained layer peels off during the first baking. May occur. Here, “dense” means “100 (volume%) − porosity (volume%)”, and “porosity (volume%)” refers to the cross-sectional polished surface of the substrate by a scanning electron microscope ( It is a value measured from the area ratio of pores observed within 50 μm in length and width when observed with SEM. Further, the “pores” referred to here are pores that are formed inside the pre-densified laminate 6 and disappear as the sintering progresses. Accordingly, when there are no pores (porosity = 0% by volume), the density becomes 100% by volume. In addition, when “densification is completed”, it means that the density becomes 97% by volume or more.

  The firing temperature (first firing temperature) in the first firing is a temperature lower than the diffusion temperature of the metal or the like constituting the conductor 2, and the density of the pre-densified laminate 6 is set in the above range. It is preferable to set the temperature as possible. For example, among the metals constituting the conductor 2, the one having the lowest diffusion temperature is silver, and the dielectric material is the “laminated body combining the high dielectric constant material and the low dielectric constant material” described above. In such a case, the first baking temperature is preferably 880 to 920 ° C, and more preferably 910 to 920 ° C. If it is lower than 880 ° C., it becomes difficult to make the density of the laminate 6 before densification 85% by volume or more, and if it is higher than 920 ° C., silver may diffuse. The first firing temperature can be appropriately determined depending on the types of the conductor 2 and the dielectric material, and is not limited to the above examples.

  Next, the ceramic constrained layer 4 is removed from the composite 5, and the pre-densified laminate 6 is taken out. The method for removing the ceramic constraining layer 4 is not particularly limited, and wet blasting, sand blasting, water jet, ultrasonic cleaning, or the like can be used.

  Next, the obtained pre-densified laminate 6 is fired at a temperature (second firing temperature) equal to or lower than the firing temperature (first firing temperature) in “first firing” (second firing). Then, the densification of the laminate 6 before densification is completed to obtain the ceramic multilayer substrate 7. Since the second firing is performed on the pre-densification laminate 6 with the ceramic constrained layer 4 removed, the density is reduced while preventing the surface of the laminate 6 (ceramic laminate substrate 7) from peeling off. Ceramic laminated substrate 7 having a high (97 volume% or more) can be obtained. And since there is no restraint by the ceramic restraint layer 4, it becomes possible to complete densification at a low temperature compared with the case where there is restraint. Further, in the laminate 6 before densification, the densification of the central part in the thickness direction is more advanced than the densification of the surface layer part. Since there is little shrinkage | contraction, it plays the role as a constrained layer, and the function which suppresses baking shrinkage when the densification of a surface layer part advances. Therefore, at the time of the second firing, the shrinkage in the XY plane can be easily reduced, and a state with high surface position accuracy can be easily maintained.

  By setting the second baking temperature to be equal to or lower than the first baking temperature, dimensional change and substrate warpage can be suppressed. The temperature difference between the first firing temperature and the second firing temperature is preferably 50 ° C. or less, and more preferably 0 to 20 ° C. When the temperature difference is larger than 50 ° C., the time for completing the densification may be long in the second baking, and the densification may not be completed.

  The difference between the density of the pre-densified laminate 6 and the density of the ceramic laminated substrate 7 is preferably 2 to 12% by volume, and more preferably 3 to 8% by volume. By setting the difference in the fine density in such a small range, the change in the fine density is small, so that the shrinkage in the XY plane is reduced even if the second firing is not performed in a restrained state, and the surface position is reduced. It becomes possible to maintain a highly accurate state. When the difference between the density of the pre-densification laminate 6 and the density of the ceramic laminate substrate 7 is less than 2% by volume, it is assumed that the resulting ceramic laminate substrate 7 has been densified. Then, the density of the laminate 6 before densification is high, and the constrained layer peeling of the laminate 6 before densification may occur. If the volume is larger than 12% by volume, the change in density is large, so that the shrinkage in the XY plane of the pre-densification laminate 6 (ceramic laminate substrate 7) becomes large during the second firing, and the surface position accuracy is maintained high. There are things you can't do.

The obtained ceramic laminated substrate 7 preferably includes a layer having a relative dielectric constant of 25 to 150, and more preferably includes a layer of 40 to 100. In the case of sintering a material having a high relative dielectric constant such as ceramics, there is a characteristic that sintering is difficult to proceed and densification is difficult compared to the case of sintering a material having a low relative dielectric constant such as glass. Therefore, the method for producing a ceramic laminate of the present invention is particularly effective when producing a ceramic laminated substrate having a high relative dielectric constant such as the above-mentioned relative dielectric constant range. In the case of manufacturing a multilayer substrate consisting of only layers having a relative dielectric constant lower than 25, sintering is easy to proceed. Therefore, even in a constrained state, a dense multilayer substrate can be obtained without causing problems such as constrained layer peeling at a low temperature. Therefore, unlike the present invention, it is not necessary to perform the firing separately in the first firing and the second firing. On the other hand, when the relative dielectric constant is higher than 150, the conductor wiring becomes too fine for the design of the high-frequency circuit, so that it may be difficult to manufacture by a process excellent in mass productivity such as printing.

  When the ceramic laminated substrate is produced by the method for producing a ceramic laminated substrate of the present embodiment, the shrinkage in the XY plane from the state of the laminated body to the ceramic laminated substrate is preferably 5% or less, More preferably, it is 3% or less. The shrinkage in the XY plane is a value obtained by defining a position 10 mm inside from a corner as a measurement point in a substrate size of 150 mm, measuring a dimension between adjacent measurement points, and averaging the dimensional change. Thus, according to the manufacturing method of the ceramic laminated substrate of this Embodiment, since shrinkage | contraction in XY plane can be made small, it becomes possible to enlarge the magnitude | size of one ceramic laminated substrate. That is, even when the size of one ceramic laminated substrate is increased, for example, when used as an LTCC substrate, it is possible to avoid the problem of deformation such as an internal wiring pattern due to contraction in the XY plane. Thereby, a large number of large LTCC substrates can be formed in one ceramic laminated substrate. As for the size of one ceramic laminated substrate, when the shape is a square, the length of one side is preferably 500 mm or less, more preferably 100 to 300 mm, and more preferably 150 to 250 mm. It is particularly preferred.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(Preparation of molding raw materials)
Dielectric green sheet forming raw materials:
(Preparation of high dielectric constant material powder)
High purity barium carbonate, titanium oxide, neodymium oxide, each powder of bismuth _oxide, were weighed to a molar ratio of _{0.16BaO-0.67TiO} 2 -0.14NdO _1.5 -0.03BiO 1.5 Wet mixed. This powder was calcined at 1250 ° C. for 4 hours to obtain a calcined powder. In order to investigate the crystal phase and crystallinity of the calcined product, powder X-ray diffraction measurement was performed. Thereafter, the calcined powder was pulverized with a ball mill until the median diameter became 0.8 μm or less, and the powder was dried to obtain ceramic powder (high dielectric constant material powder). The particle size was measured by a dynamic light scattering method using a dynamic light scattering photometer DSL7000 manufactured by Otsuka Electronics Co., Ltd.

(Preparation of low dielectric constant material powder)
High purity barium carbonate, alumina, silica, powders of bismuth oxide _were weighed so that the molar ratio of _{0.27BaO-0.03AlO 1.5 -0.64SiO 2 -0.06BiO 1.5} . After that, a low dielectric constant material powder was produced by the same method as the high dielectric constant material.

(Preparation of glass powder)
Each powder of zinc oxide, boron oxide and silica was weighed and dry-mixed, the mixed powder was melted in a platinum crucible, and the melt was dropped into water and rapidly cooled to obtain a massive glass. This glass was wet pulverized until the median diameter became 4 μm or less to obtain a low-melting glass powder. The weight ratio of zinc oxide, boron oxide and silicon oxide was 62: 29: 9% by weight.

Example 1
To a mixture of equal amounts of toluene and isopropanol as a dispersion medium, the above-mentioned dielectric raw material (high dielectric constant material powder), glass powder, and polyvinyl butyral as a binder are mixed, respectively. A forming raw material was produced. The amount of each raw material used was 2.5 parts by mass of glass, 7.5 parts by mass of the binder, and 1.5 parts by mass of the dispersion medium with respect to 100 parts by mass of the dielectric material. Next, the obtained forming raw material was stirred and defoamed under reduced pressure to prepare a viscosity of 1500 to 2000 cP. The viscosity of the slurry was measured with an LVT viscometer manufactured by Brookfield.

Molding raw material for ceramic constrained layer:
To a mixture of equal amounts of toluene and isopropanol as a dispersion medium, alumina as a ceramic material and polyvinyl butyral as a binder were mixed, respectively, to prepare a forming material for a slurry-like ceramic constraining layer. The amount of each raw material used was 7.5 parts by mass of the binder and 1.5 parts by mass of the dispersion medium with respect to 100 parts by mass of the ceramic raw material. Next, the obtained forming raw material was stirred and defoamed under reduced pressure to prepare a viscosity of 1500 to 2000 cP. The viscosity of the slurry was measured with an LVT viscometer manufactured by Brookfield.

Molding:
Next, the forming raw material for the slurry-like dielectric green sheet and the forming raw material for the ceramic constraining layer obtained by the above method were each formed into a sheet using the doctor blade method. The thickness of the obtained dielectric green sheet was 40 μm and 80 μm. Moreover, the thickness of the obtained sheet | seat for constrained layers was 125 micrometers.

  A conductor was disposed on the surface of the obtained dielectric green sheet. To the silver powder, terpineol as a solvent and polyvinyl butyral as a binder were added and sufficiently kneaded to prepare a conductor paste. The obtained conductor paste was printed on the surface of the dielectric green sheet using screen printing to form a conductor in the shape of a capacitor electrode pattern and a resonator pattern.

  Next, sheets having a thickness of 40 μm and 80 μm are appropriately selected according to the element design, 10 dielectric green sheets are laminated, and a sheet for a constraining layer is laminated on both sides of the laminated dielectric green sheets, Pressurization was performed using a uniaxial press machine. Thereby, the composite_body | complex with which the ceramic constrained layer was arrange | positioned on both surfaces of the laminated body was obtained.

First firing:
The obtained composite was degreased at 400 ° C. for 5 hours, and further fired at 920 ° C. for 1.5 hours, whereby the laminate in the composite was used as a pre-densified laminate. The porosity of the laminate before densification after the first firing was 12% by volume. Accordingly, the density was 88% by volume. The porosity of the laminate before densification after the first firing was measured by cutting out a part of the composite after the first firing. The porosity was measured from the area ratio of the pores observed within 50 μm in length and breadth when the cross-section polished surface of the substrate was observed with a scanning electron microscope (JSM-6390 manufactured by JEOL). Firing was performed using an electric furnace.

(Removal of ceramic constrained layer)
From the first fired composite, the ceramic constrained layer was removed using a method of washing with water and ultrasonic cleaning, and the pre-densified laminate was taken out.

Second firing:
The laminated body before densification was fired at 920 ° C. for 1.5 hours to complete the densification, and a ceramic multilayer substrate was obtained. The porosity of the ceramic laminated substrate was 3% by volume. Accordingly, the density was 97% by volume.

(Evaluation methods)
About the obtained ceramic laminated substrate (laminated substrate), “peripheral peeling” and “dimensional accuracy” were evaluated by the following methods. The results are shown in Table 1. In Table 1, “Dense” in the first firing column is the density of the pre-densification laminate, and “Density” in the second firing column is the density of the ceramic laminated substrate.

(Peripheral peeling)
After peeling the constraining layer, the outer peripheral portion was less adhered to the constituent particles of the constraining layer than the inside, and further, when the substrate warp was considered to be caused by the fact that it was not constrained during firing, it was determined as defective. Warpage is defined as a deviation of the outer peripheral portion by 1 mm or more with respect to a horizontal plane at the center of the substrate when the surface of the substrate is measured with a contact surface roughness meter (Form Talysurf PGI 1240 manufactured by Taylor Hobson). Of the five substrates of the same level, the number of substrates on which peeling occurred and zero was accepted.

(Dimensional accuracy)
The shrinkage in the XY plane is defined as a measurement point 10 mm inward from the outer periphery at a substrate size of 150 mm, measuring four locations in the X direction and four locations in the Y direction, and calculating the ratio with the dimensions before firing. And the dimensional change rate. When the number of evaluation substrates was five, the difference between the maximum value and the minimum value of the dimensional change rate with respect to a total number of measurements of 40 was defined as dimensional accuracy (%), and 0.05% or less was accepted.

(Example 2)
By setting the firing temperature of the first firing to 950 ° C., the density of the laminate before densification is set to 95% by volume, and by setting the firing temperature of the second firing to 950 ° C., the density of the ceramic laminate substrate A ceramic laminated substrate was produced in the same manner as in Example 1 except that the content was changed to 99% by volume. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Example 3)
A ceramic laminated substrate was produced in the same manner as in Example 1 except that the low dielectric constant material was used as the dielectric material. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

Example 4
A ceramic laminated substrate was produced in the same manner as in Example 3 except that the firing temperature of the second firing was 870 ° C. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Example 5)
A ceramic laminated substrate was produced in the same manner as in Example 3 except that the firing temperature of the second firing was 860 ° C. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Example 6)
A ceramic laminated substrate was produced in the same manner as in Example 3 except that the firing temperature of the first firing was 940 ° C. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Example 7)
A ceramic laminated substrate was produced in the same manner as in Example 3 except that the firing temperature for the first firing was 860 ° C. and the firing temperature for the second firing was 870 ° C. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Comparative Example 1)
By setting the firing temperature of the first firing to 980 ° C., the density of the laminate before densification was set to 97% by volume, and the second firing was not performed, in the same manner as in Example 1, except that the ceramic laminate was laminated. A substrate was produced. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Comparative Example 2)
A ceramic laminated substrate was produced in the same manner as in Example 1 except that the firing temperature of the first firing was 880 ° C., so that the density of the laminate before densification was 84% by volume. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Comparative Example 3)
The dielectric material is the low dielectric constant material, and the firing temperature of the first firing is 950 ° C., so that the density of the laminate before densification is 96% by volume and the second firing is not performed. In the same manner as in Example 1, a ceramic laminated substrate was produced. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

(Comparative Example 4)
By using the dielectric material as the low dielectric constant material and setting the firing temperature of the first firing to 840 ° C., the density of the laminate before densification is 84% by volume, and the firing temperature of the second firing is 870 ° C. Thus, a ceramic laminated substrate was produced in the same manner as in Example 1 except that the density of the ceramic laminated substrate was 98% by volume. About the obtained ceramic laminated substrate, "peripheral peeling" and "dimensional accuracy" were evaluated by the above methods. The results are shown in Table 1.

  The method for producing a ceramic laminated substrate of the present invention can be suitably used for producing an LTCC substrate used for a high frequency filter or the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram explaining one Embodiment of the manufacturing method of the ceramic laminated substrate of this invention, Fig.1 (a) shows a laminated body and a ceramic constrained layer (sheet | seat for constrained layers), FIG.1 (b) Shows the composite at the time of the first firing, and FIG. 1C shows the pre-densified laminate (ceramic laminate substrate) at the time of the second firing.

Explanation of symbols

1: dielectric green sheet, 2: conductor, 3: laminate, 4: ceramic constrained layer (constraint layer sheet), 5: composite, 6: pre-densified laminate, 7: ceramic laminated substrate.

Claims (7)

Forming a plurality of dielectric green sheets containing ceramics and glass;
A conductor is disposed on at least one surface of the at least one dielectric green sheet;
A laminate is formed by laminating the plurality of dielectric green sheets, and a composite body is formed on both surfaces of the laminate by disposing ceramic constraining layers that are not sintered at the firing temperature of the laminate,
Firing of the composite (first firing) is started, and before the densification of the laminate is completed, the first firing is finished, and the laminate in the composite is pre-densified. age,
Removing the ceramic constraining layer from the composite;
The obtained layered body before densification is fired at a temperature (second firing temperature) that is equal to or lower than the firing temperature (first firing temperature) in the first firing, so that the layered body before densification is densified. A method for manufacturing a ceramic laminated substrate that is completed by completing the process.   The method for producing a ceramic laminated substrate according to claim 1, wherein the density of the laminate before densification is 85 to 95% by volume.   The method for producing a ceramic laminated substrate according to claim 1 or 2, wherein a temperature difference between the first firing temperature and the second firing temperature is 50 ° C or less.   The method for producing a ceramic laminated substrate according to any one of claims 1 to 3, wherein a difference between the density of the pre-densified laminate and the density of the ceramic laminated substrate is 2 to 12% by volume.   The method for producing a ceramic laminated substrate according to any one of claims 1 to 4, wherein a ceramic content of the dielectric green sheet is 90% by mass or more.   The method for producing a ceramic laminated substrate according to claim 1, wherein at least one of the plurality of dielectric green sheets is formed of a material different from that of other dielectric green sheets. The method for producing a ceramic laminated substrate according to claim 1, comprising a layer having a relative dielectric constant of 2 5 to 1 5 0.

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