JP2006181737A - Composite ceramic green sheet, method for manufacturing composite ceramic green sheet, and method for manufacturing multilayer ceramic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer ceramic in which insulating layers of two or more kinds of constituent materials are laminated, there are few regions where constituent materials are mixed at the interface between the insulating layers, the material characteristics are stable, and delamination does not occur between the insulating layers. A substrate is manufactured.
[Solution]
A composite in which a second insulating layer is formed by applying and drying a slurry containing the second inorganic powder and the second organic binder on the first insulating layer made of the first inorganic powder and the first organic binder. In the ceramic green sheet, a region where the first inorganic powder and the second inorganic powder exist in the vicinity of the interface between the first insulating layer and the second insulating layer, and / or the first organic The region where the binder and the second organic binder are mixed has a thickness of 0.3 to 8 μm.
[Selection] Figure 1

Description

  The present invention relates to a composite ceramic green sheet, a method for producing the same, and a method for producing a multilayer ceramic substrate using the same.

In recent years, various properties are required for multilayer ceramic substrates, and various properties are also required for ceramic green sheets used for manufacturing to realize them. Among them, there is a composite ceramic green sheet in which two kinds of materials are formed in layers in a ceramic green sheet, and this composite ceramic green sheet is composed of a first inorganic powder, a first organic binder, and a first solvent. A second slurry composed of a second inorganic powder, a second organic binder, and a second solvent is applied in a layer and dried on the first insulating layer formed by applying and drying the first slurry in a layer. Thus, a second insulating layer is formed. (For example, see Patent Document 1)
In the case of manufacturing a multilayer ceramic substrate, a plurality of the above-mentioned composite ceramic green sheets are prepared, via-hole conductors for establishing conduction between layers and wiring conductors constituting a circuit are formed on each composite ceramic green sheet, and the composite ceramic green sheets are formed. A plurality of ceramic green sheets are laminated, and then the laminate is fired. Here, the formation of the via-hole conductor is performed by punching or the like, filling and drying of the conductor paste, and the formation of the wiring conductor constituting the circuit is performed by printing or drying the conductor paste.
Japanese Patent Laying-Open No. 2004-235207 (page 5, FIG. 2)

  However, in the above-described composite ceramic green sheet, in the vicinity of the interface of the insulating layer, the thickness of the region where the powder, organic binder, or other constituent materials included in each layer are mixed is large, and the thickness and concentration of the mixed region are large. However, the material characteristics after firing fluctuated.

  FIG. 6 is a schematic view of a cross section near the interface between two insulating layers of a composite ceramic green sheet according to the prior art. 21 is a first inorganic powder, 22 is a second inorganic powder, 31 is a first organic binder, 32 is a second organic binder, and 33 is a mixture of the first organic binder and the second organic binder. It is an area. Further, 51 is a region composed only of the first insulating layer component, 52 is a region composed only of the second insulating layer component, and 53 is a first insulating layer component and the second insulating layer. This is a region where the layer components are mixed.

  As shown in FIG. 6, when the second slurry is applied, the second solvent dissolves the first organic binder contained in the first insulating layer. The region 53 where the components of the insulating layer are mixed becomes larger. Further, in this region 53, the respective components are non-uniform, and the region 51 is composed of only the first insulating layer component in the composite ceramic grease sheet, and is composed of only the second insulating layer component. The thickness variation of each layer of the region 53 in which the component of the first insulating layer and the component of the second insulating layer are mixed is large. Since the region 53 where the inorganic powder of the first insulating layer and the inorganic powder of the second insulating layer are mixed is increased, the composition is different from the originally designed composition. The shrinkage behavior of each material during firing may change and cause deformation and cracks. In addition, because the thickness variation of each layer in the composite ceramic green sheet is large, the characteristics of the elements in the multilayer ceramic substrate fluctuate, and the shrinkage during firing locally differs in the ceramic component, so deformation and cracking occur Sometimes happened.

  Therefore, as a method for producing a composite ceramic green sheet, it is conceivable to form the first insulating layer and the second insulating layer separately, and join them by thermocompression bonding or adhesion liquid.

  FIG. 7 is a schematic view of a cross section in the vicinity of the interface between two insulating layers of a composite ceramic green sheet bonded by thermocompression bonding or adhesion liquid. 21 is a first inorganic powder, 22 is a second inorganic powder, 31 is a first organic binder, and 32 is a second organic binder. Further, 61 is a region composed only of the first insulating layer component, 62 is a region composed only of the second insulating layer component, and 63 is the first insulating layer component and the second insulating layer. This is a region where the layer components are mixed.

  However, in these methods, as shown in FIG. 7, the first organic binder 21 and the second organic binder 22 cannot be closely bonded, and there is a problem that the insulating layer is not sufficiently bonded.

  The present invention has been devised in view of the above-mentioned problems, and its purpose is to form a composite ceramic green sheet in which two types of insulating layers are formed in layers and there are few regions where constituent materials are mixed at the interface between them. A composite ceramic green sheet having stable material properties after firing and having strong bonding between two insulating layers and no delamination, a manufacturing method thereof, and a multilayer ceramic substrate using the composite ceramic green sheet It is to provide a manufacturing method.

  The composite ceramic green sheet of the present invention is obtained by applying and drying a slurry containing the second inorganic powder and the second organic binder on the first insulating layer composed of the first inorganic powder and the first organic binder. In the composite ceramic green sheet forming the second insulating layer, a region where the first inorganic powder and the second inorganic powder are mixed in the vicinity of the interface between the first insulating layer and the second insulating layer. And / or a region in which the first organic binder and the second organic binder are mixed, and the thickness of the mixed region is 0.3 to 8 μm.

  Also, the method for producing a composite ceramic green sheet of the present invention includes a first insulation formed by applying and drying a first slurry comprising a first inorganic powder, a first organic binder, and a first solvent in layers. In a method for producing a composite ceramic green sheet, a second insulating layer is formed by applying and drying a second slurry composed of a second inorganic powder, a second organic binder, and a second solvent on a layer in a layered manner. The solubility of the first organic binder in the second solvent is 2% or less.

  Furthermore, the method for producing a composite ceramic green sheet of the present invention is characterized in that the solubility of the second organic binder in the second solvent is 5% or more.

  Furthermore, the method for producing a composite ceramic green sheet of the present invention is characterized in that the solubility parameter (hereinafter referred to as SP value) of the second solvent is 11 or more.

  Furthermore, in the method for producing a composite ceramic green sheet of the present invention, the second solvent is water, alcohol, polyhydric alcohol, polyhydric alcohol alkyl ether, amide, carbonyl, or a mixed solvent thereof. It is a feature.

  Furthermore, in the method for producing a multilayer ceramic substrate of the present invention, a wiring conductor constituting a circuit is formed on a composite ceramic green sheet, and a via-hole conductor penetrating the sheet is formed in the thickness direction, and a plurality of the composite ceramic green sheets are formed. It laminates | stacks and, after that, the said laminated body is baked.

  According to the composite ceramic green sheet of the present invention, the first inorganic powder and the second inorganic powder existing in the vicinity of the interface between the first insulating layer and the second insulating layer are mixed and / or The thickness of the region where the first organic binder and the second organic binder are mixed is set to 0.3 to 8 μm.

  First, regarding the region where the inorganic powder is mixed, the region where the inorganic powder is mixed is 8 μm or less, so that the composition of each layer becomes the originally designed composition. The shrinkage behavior of each material inside changes, and no deformation or cracking occurs. In addition, since the thickness of each layer is constant in the composite ceramic green sheet, the characteristics of the elements in the multilayer ceramic substrate may fluctuate, and the shrinkage during firing may vary locally within the ceramic component, causing deformation and cracks. I don't have to. Even if there is no adhesive force due to the organic binder between the first inorganic powder and the second inorganic powder after the binder removal is completed, the region where the inorganic powder is mixed is 0.3 μm or more. In addition, since the inorganic powders are not separated between the layers, the layers are not separated in the firing step.

  Next, regarding the area where the organic binder is mixed, the area where the organic binder is mixed is 8 μm or less, so that the strength, ease of deformation, density, etc. of the composite ceramic green sheet are constant within the composite ceramic green sheet. Thus, in the process of drying, laminating, etc. in the manufacturing process of the multilayer ceramic substrate, stress is generated due to non-uniformity of these characteristics, and deformation and cracks do not occur. In addition, even if the thermal decomposition characteristics of the binder are different, the binder is uniformly removed at the time of binder removal for firing, and deformation and cracks do not occur. Furthermore, since the region where the organic binder is mixed becomes 0.3 μm or more, the first organic binder and the second organic binder are closely bonded via the region where the organic binder is mixed. Even if a stress such as a stress due to processing of the ceramic green sheet or heat due to drying is applied, delamination does not occur in the composite ceramic green sheet processing step.

  Further, according to the method for producing a composite ceramic green sheet of the present invention, the first slurry composed of the first inorganic powder, the first organic binder, and the first solvent is formed and dried in a layered manner. On the first insulating layer, a second slurry composed of the second inorganic powder, the second organic binder, and the second solvent is applied in layers and dried to form a second insulating layer. In the composite ceramic green sheet preparation method, the solubility of the first organic binder in the second solvent is 2% or less. This makes it difficult for the second solvent to dissolve the organic binder of the first insulating layer when the second slurry is applied on the first insulating layer. For this reason, the thickness of the region where the inorganic powder, organic binder, or other constituent material of the first insulating layer and the inorganic powder, organic binder, or other constituent material of the second slurry are mixed decreases. The thickness and concentration non-uniformity of the mixed region is inevitably reduced, so that the material properties after firing are stable as described above, and deformation and cracks do not occur in the manufacturing process.

  Furthermore, according to the method for producing a composite ceramic green sheet of the present invention, since the solubility of the second organic binder in the second solvent is 5% or more, the second organic in the second slurry. Since the binder is uniformly dispersed and the distribution of the inorganic powder and the organic binder is uniform in the second insulating layer, the material characteristics after firing are stable, and deformation and cracks do not occur in the manufacturing process.

  Furthermore, according to the method for producing a composite ceramic green sheet of the present invention, a solvent having an SP value of 11 or more is used as the second solvent. A solvent having an SP value of 11 or more is difficult to dissolve the first organic binder. Therefore, when the second slurry is applied on the first insulating layer, the second solvent is the first solvent. It becomes difficult to dissolve the organic binder of 1. Therefore, the thickness of the region where the inorganic powder of the first insulating layer, the organic binder, or other constituent materials and the inorganic powder of the second slurry, the organic binder, or other constituent materials are mixed, is reduced. Since the thickness and concentration non-uniformity of the mixed region is inevitably reduced, as described above, the material characteristics after firing are stable, and deformation and cracks do not occur in the manufacturing process.

  Furthermore, according to the method for producing a composite ceramic green sheet of the present invention, water, alcohol, polyhydric alcohol, polyhydric alcohol alkyl ether, amide, carbonyl or a mixed solvent thereof is used as the second solvent. is doing. Since these solvents are difficult to dissolve the first organic binder, when the second slurry is applied on the first insulating layer, the second solvent removes the first organic binder. It becomes difficult to melt. Therefore, the thickness of the region where the inorganic powder of the first insulating layer, the organic binder, or other constituent materials and the inorganic powder of the second slurry, the organic binder, or other constituent materials are mixed, is reduced. Since the thickness and concentration non-uniformity of the mixed region is inevitably reduced, as described above, the material characteristics after firing are stable, and deformation and cracks do not occur in the manufacturing process.

  Still further, according to the method for manufacturing a multilayer ceramic substrate of the present invention, a via hole conductor for establishing electrical conduction between layers is formed on the composite ceramic green sheet, and a wiring conductor constituting a circuit is formed by combining the via hole conductor. A plurality of ceramic green sheets are laminated, and then the laminate is fired. In the method for producing a composite ceramic green sheet of the present invention, since the second insulating layer is applied on the first insulating layer in a slurry state, it can be closely bonded to obtain a strong bond. As a result, stress due to processing in the via hole conductor or wiring conductor formation step in the manufacturing method of the multilayer ceramic substrate, stress such as heat due to drying is applied, and the time from bonding to firing is increased. Even delamination can be eliminated.

  Hereinafter, a composite ceramic green sheet according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a composite ceramic green sheet according to the present invention, in which 1 is a first insulating layer and 2 is a second insulating layer. The first insulating layer 1 is composed of a first inorganic powder and a first organic binder, and the second insulating layer 2 is composed of a second inorganic powder and a second organic binder. The thickness of the 1st insulating layer 1 and the 2nd insulating layer 2 is set to 5-300 micrometers, for example. In FIG. 1, although the thickness of the 1st insulating layer 1 and the thickness of the 2nd insulating layer 2 are shown substantially the same, each thickness can be set separately so that the below-mentioned characteristic may be satisfy | filled.

Inorganic powder materials include insulator ceramics such as alumina and mullite, dielectric ceramics such as BaTiO ₃ and SrTiO ₃ , magnetic ceramics such as ferrite, and can be fired at a relatively low temperature of 800 ° C. to 1200 ° C. For example, glass ceramics in which 10 to 100% by weight of glass and 90 to 0% by weight of the above insulator ceramics, dielectric ceramics, and magnetic ceramics are mixed are used. It should be noted that by making the composition of the first insulating layer 1 and the second insulating layer 2 different, the multilayer substrate after firing has various characteristics, and the characteristics of each layer during the manufacture of the multilayer substrate are different. Thus, the manufacturing method can have various characteristics.

  Examples of the different characteristics imparted to each layer include the following. If insulating layers with different dielectric characteristics and magnetic characteristics are used, a part with a high dielectric constant, a part with a high Q, a part with a high magnetic property, etc. can be made. be able to. By using an insulating layer with strong bending strength, an insulating layer with few defects on the surface and an insulating layer with excellent corrosion resistance, the origin of cracks is eliminated (after chemical treatment such as plating), and a multilayer board is created. A substrate with excellent bending strength and drop impact resistance can be produced. If the temperature at which the insulating layer shrinks by firing is different, the behavior of shrinking each other is suppressed, so that the shrinkage in the planar direction during firing is reduced and a substrate with good dimensional accuracy can be obtained. If the strength, elongation, and fluidity of the organic binder are changed by the insulating layer, there is an insulating layer that is not easily deformed, so that the dimensional accuracy is maintained, and at the same time, there is an insulating layer that is easily deformed, thereby eliminating the occurrence of cracks. it can.

  Further, the case where the first and second insulating layers are glass ceramics will be specifically described.

As the composition of the glass powder, for example, as an essential component, SiO ₂ is 10 to 70% by weight, Al ₂ O ₃ is 0.5 to 30% by weight, MgO is 3 to 60% by weight, and optional components are CaO. 0 to 35 wt%, a BaO 0-35% by weight, the SrO _0-35% by _weight, B 2 _{O 3} 0 to 20 wt%, 0-30 wt% of ZnO, the TiO ₂ 0 wt%, Na ₂ O 0 to 3 wt%, the Li ₂ O can be exemplified those containing 0 and 5 wt%.

As the ceramic powder, at least one selected from Al ₂ O ₃ , SiO ₂ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ , Mg ₂ SiO ₄ , BaTi ₄ O ₉ , ZrTiO ₄ , SrTiO ₃ , BaTiO ₃ , TiO ₂ is used. Can be mentioned. Al ₂ O ₃ is a preferable material because it has high strength and is particularly excellent in corrosion resistance. Since SiO ₂ and Mg ₂ SiO ₄ have a relatively low dielectric constant, they are suitable for use in a low dielectric constant layer in a case where the dielectric constant is different. It is also possible to use a powder in which is hollowed. Since CaTiO ₃ , SrTiO ₃ , and TiO ₂ have a negative dielectric constant temperature characteristic, the temperature characteristic of the dielectric constant of the composite ceramic material is within about ± 60 ppm / ° C. in combination with other materials having a positive temperature characteristic. This is a preferable material for preventing the characteristics of capacitors and filters from fluctuating with temperature. MgTiO ₃ and CaTiO ₃ are materials that are easier to sinter than Al ₂ O _{3 and the} like, and are less than the temperature at which a metal with low conductor resistance such as gold, silver, and copper, such as gold, silver, and copper, melts in a small amount of glass. Since it can be sintered and has a high Q, it is a material suitable for a substrate constituting a high-frequency inductor, capacitor, filter or the like. BaTiO ₃ has a high dielectric constant and is a material suitable for incorporating a high-capacitance capacitor.

  According to the combination of glass powder 10 to 100% by weight and ceramic powder 90 to 0% by weight, low temperature sintering at 1000 ° C. or lower is possible, and silver (melting point 960 ° C.), copper as a conductor It can be formed using a low resistance conductor such as (melting point 1083 ° C.) or gold (melting point 1063 ° C.), and a low-loss circuit can be created. In addition, the dielectric constant and the temperature characteristics of the dielectric constant can be controlled, and the circuit is suitable for downsizing the circuit and reducing the loss by increasing the dielectric constant, or for high-speed transmission by reducing the dielectric constant. In addition, by controlling various compositions within the above range, the firing shrinkage behavior can be easily controlled and changed.

  Next, the average particle size of the first and second inorganic powders is 0.1 to 5.0 μm, and more preferably 0.3 to 3.0 μm. If the particle size is 5.0 μm or more, the powder is too large, and it is difficult to obtain a slurry in which the powder is uniformly dispersed. Therefore, an insulating layer having no defect cannot be obtained. In addition, if the average particle size is large, the sinterability is poor. For these reasons, the average particle size is preferably 5.0 μm or less, more preferably 3.0 μm or less. Conversely, if the average particle size is small, the powder tends to agglomerate due to van der Waals force, and it becomes difficult to loosen the agglomeration. As a result, it is difficult to obtain a slurry in which the powder is uniformly dispersed, and therefore, an insulating layer having no defect cannot be obtained. In addition, since the area where the powder and the solvent are in contact with each other increases, some of the components of the powder are eluted into the solvent, and the properties of the ceramic after firing fluctuate, and the eluted components cause viscosity characteristics abnormalities such as gelation of the slurry. This makes it impossible to continue the process. For these reasons, the average particle size is preferably 0.1 μm or more, more preferably 0.3 μm or more. In general, the smaller the average particle size, the better the sinterability, but the handling such as slurrying of the powder becomes difficult. In addition, if the powder is made by crushing the raw material, if the average particle size is reduced, there will be problems such as increased contamination during pulverization and increased cost due to increased pulverization time. Among the average particle diameters that can obtain the required sinterability, those having a relatively large average particle diameter are used. In particular, in insulating ceramics and dielectric ceramics, those having a thickness of 1.0 μm or less are used in order to sinter at a temperature below that at which a metal with low conductor resistance such as gold, silver and copper melts.

  Examples of the organic binder include acrylic resin, methacrylic resin, urethane resin, and vinyl acetal resin. Acrylic resins and methacrylic resins are preferable materials because of their good thermal decomposability, and among these, methacrylic acid resins are particularly preferable materials because of their particularly good thermal decomposability. Vinyl acetal resin is a preferable material because it has high toughness, can increase the strength and elongation of the composite ceramic green sheet, can effectively prevent the occurrence of cracks in the processing step before firing, and has high accuracy after processing.

  Then, the manufacturing method of the composite ceramic green sheet which is embodiment of this invention is demonstrated.

  2A and 2B are cross-sectional views of the manufacturing process of the composite ceramic green sheet. In the figure, 6 is a first slurry, 7 is a second slurry, 8 is a support film, and 9 is a doctor blade.

First, as a first inorganic powder, the composition is SiO ₂ 33 wt%, Al ₂ O ₃ 3.4 wt%, MgO 13 wt%, CaO 15 wt%, BaO 0.3 wt%, SrO 35% by weight, B ₂ O ₃ 0.2% by weight, Li ₂ O 0.1% by weight and an average particle diameter of 1.5 μm glass powder 55% by weight and Al ₂ O ₃ A mixture prepared by mixing 45% by weight of 1.6 μm ceramic powder is prepared. A carboxyl group is added to the acrylic resin as a first organic binder to the first inorganic powder to give an acid value of 0.5 KOH mg / g, toluene as the first solvent, DOP as the plasticizer, and polyoxy as the dispersant The alkylene acrylic ether is put in a ball mill and mixed and pulverized for 40 hours to obtain a first slurry. FIG. 2A is a cross-sectional view of a process in which the first slurry 6 is applied on the support film 8. The doctor blade 9 in the figure is fixed, and the thickness of the first support film 8 is fixed between the doctor blade 9 and the support film 8 by conveying the support film 8 below from the left to the right in the figure. The slurry 6 is applied in a thin layer on the support film 8. The first solvent is dried on the applied first slurry by heat, infrared rays or the like, and the first insulating layer 1 is formed. Examples of the first solvent include toluene, methyl ethyl ketone, ethyl acetate, or a mixture thereof.

Next, as the second inorganic powder, the composition is SiO ₂ 40 wt%, Al ₂ O ₃ 2 wt%, MgO 15 wt%, CaO 1 wt%, BaO 15 wt%, B ₂ O ₃ 20% by weight of ZnO, 1% by weight of ZnO, 0.5% by weight of TiO ₂ , 0.5% by weight of Na ₂ O and 5% by weight of Li ₂ O And 20% by weight of a ceramic powder having an average particle diameter of 0.8 μm made of Al ₂ O ₃ is prepared. A carboxyl group is added to the acrylic resin as a second organic binder to the second inorganic powder to give an acid value of 20 KOHmg / g, water as the second solvent, polyethylene glycol as the plasticizer, and an acid value of 100 KOHmg / g as the dispersant. g of a high acid value methacrylic acid resin is put in a ball mill and mixed and pulverized for 40 hours to obtain a second slurry. FIG. 2B is a cross-sectional view of a process in which the second slurry 7 is applied onto the first insulator layer 1 formed on the support film 8. The doctor blade 9 in the figure is fixed, and the support film 8 on which the first insulating layer 1 thereunder is formed is conveyed from the left to the right in the figure, whereby the doctor blade 9 and the first insulation are formed. The second slurry 7 having a constant thickness between the layers is thinly applied in layers on the first insulating layer 1 formed on the support film 8. The applied second slurry is dried by heat, infrared rays, or the like, and the second solvent is dried to form a second insulating layer, thereby obtaining a composite green sheet 3 composed of the first, insulating layer 1, and second insulating layer 2. I can do it. In addition to the doctor blade, examples of the molding method include a lip coater, a die coater, and a roll coater. Examples of the material of the support film 8 include PET and PEN. In addition, the first slurry and the second slurry may contain other additives such as pigments, antifoaming agents, pH adjusting agents, etc., and these additives are the same in the first slurry and the second slurry. Or it can be different. Furthermore, as a plasticizer, what has a high plasticizing effect with respect to a 1st organic binder is used suitably, DOP, DBP, DOA etc. can be illustrated. DOP and DBP are preferred materials because of their high plasticizing effect. Since DOP has a high boiling point and a low vapor pressure of about room temperature to 100 ° C., the amount of evaporation from the green sheet due to heat such as drying during the green sheet preparation process or the multilayer substrate preparation process is small, which is a particularly preferable material. It is. Furthermore, the dispersant is selected from the affinity for each inorganic material, the solubility in each solvent, and the like, such as polyoxyalkylene acrylic ethers, phosphate esters, high acid value acrylic resins, high acid value methacrylic resins, etc. Can be illustrated.

  FIG. 5 is a schematic view of a cross section near the interface between two insulating layers of the composite ceramic green sheet according to the present invention. 21 is a first inorganic powder, 22 is a second inorganic powder, 31 is a first organic binder, 32 is a second organic binder, and 33 is a mixture of the first organic binder and the second organic binder. It is an area. Further, 41 is a region composed only of the first insulating layer component, 42 is a region composed only of the second insulating layer component, and 43 is the first insulating layer component and the second insulating layer. This is a region where the layer components are mixed.

  In the present embodiment, as shown in FIG. 5, a region where the components of the first insulating layer and the second insulating layer are mixed at the interface between the first insulating layer 1 and the second insulating layer 2. 43, through which the first insulating layer 1 and the second insulating layer 2 are joined. The region 43 in which the components of the first insulating layer and the second insulating layer are mixed at the interface between the first insulating layer 1 and the second insulating layer 2 includes the first inorganic powder and the second insulating layer. The region where the inorganic powder is mixed and / or the region where the first organic binder and the second organic binder are mixed, and the thickness thereof is 0.3 to 8 μm.

  First, in the region where the inorganic powder is mixed, since the region 43 where the inorganic powder is mixed is 8 μm or less, the composition of each layer becomes the originally designed composition, and at the same time, the material properties after the baking are stabilized and the baking is performed. The shrinkage behavior of each material inside changes, and no deformation or cracking occurs. In addition, since the thickness of each material is constant in the composite ceramic green sheet, the characteristics of the elements in the multilayer ceramic substrate fluctuate, and the shrinkage during firing differs locally in the ceramic part, causing deformation and cracks. There's nothing to do. Since the region 43 where the inorganic powder is mixed is 0.3 μm or more, the adhesive force due to the organic binder is lost between the first inorganic powder 21 and the second inorganic powder 22 after the binder removal is completed. However, since the inorganic powders are not separated between the layers, the layers are not separated in the firing step.

  Next, regarding the area where the organic binder is mixed, the area 43 where the organic binder is mixed is 8 μm or less, so that the strength, ease of deformation, density, etc. of the composite ceramic green sheet are constant within the composite ceramic green sheet. Thus, in the process of drying, laminating, etc. in the manufacturing process of the multilayer ceramic substrate, stress is generated due to non-uniformity of these characteristics, and deformation and cracks do not occur. In addition, even if the thermal decomposition characteristics of the binder are different, the binder is uniformly removed at the time of binder removal for firing, and deformation and cracks do not occur. Furthermore, since the region 43 where the organic binder is mixed becomes 0.3 μm or more, the first organic binder 21 and the second organic binder 22 are closely bonded via the region 43 where the organic binder is mixed. Even when stress such as stress due to green sheet processing or heat due to drying is applied, delamination does not occur in the green sheet processing step.

  Moreover, in this embodiment, the solvent whose solubility of a 1st organic binder is 2% or less is used as a solvent of a 2nd solvent. Specific examples include water, isopropyl alcohol, ethanediol, propylene glycol monoethyl ether, dimethylformamide, butyl carbitol and the like. For this reason, when the second slurry is applied on the first insulating layer 1, the second solvent is unlikely to dissolve the first organic binder. This makes it difficult for the second solvent to dissolve the organic binder of the first insulating layer when the second slurry is applied onto the first insulating layer 1. For this reason, the thickness of the region where the inorganic powder, organic binder, or other constituent material of the first insulating layer and the inorganic powder, organic binder, or other constituent material of the second slurry are mixed decreases. The thickness and concentration non-uniformity of the mixed region is inevitably reduced, so that the material properties after firing are stable as described above, and deformation and cracks do not occur in the manufacturing process.

  Further, in this embodiment, a solvent having an SP value of 11 or more is used as the second solvent. The SP value is the square root of (aggregation energy per volume) and represents the ease with which the substance aggregates. When mixing substances A and B that do not cause a chemical reaction, if the SP value of A >> SP value of B, A is agglomerated, that is, dissolved rather than a state where A and B are uniformly mixed. Since the energy in the state where it is not is lower, A and B are not dissolved together. That is, substances having a small difference in SP value dissolve each other, and substances having a large difference do not dissolve each other. Therefore, whether or not the organic binder is dissolved in a solvent depends on the SP value of each substance. Judgment is possible. For this reason, when the second slurry is applied on the first insulating layer 1, the second solvent does not dissolve the first organic binder. Thereby, when the second slurry is applied on the first insulating layer 1, the second solvent does not dissolve the organic binder of the first insulating layer. For this reason, the thickness of the region where the inorganic powder, organic binder, or other constituent material of the first insulating layer and the inorganic powder, organic binder, or other constituent material of the second slurry are mixed decreases. The thickness and concentration non-uniformity of the mixed region is inevitably reduced, so that the material properties after firing are stable as described above, and deformation and cracks do not occur in the manufacturing process.

  Furthermore, in this embodiment, water, alcohol, polyhydric alcohol, polyhydric alcohol alkyl ethers, amides, and carbonyls are used as the solvent of the second solvent. In general, the SP value increases when the difference in the distribution of polarities in the molecule is large. That is, the SP value of a solvent of a saturated compound composed only of an alkyl group is as low as about 7 whereas water is 23.4, which is the highest SP value among substances normally used as a solvent. Each solvent has a value between about 7 and 23.4 depending on the distribution of its polarity, and the relationship of SP values is roughly saturated compounds <ketones <alcohols <polyhydric alcohols, polyhydric alcohol alkyls. Ethers, amides, carbonyls <water. For this reason, when the second slurry is applied on the first insulating layer 1, the second solvent does not dissolve the first organic binder. Thereby, when the second slurry is applied on the first insulating layer 1, the second solvent does not dissolve the organic binder of the first insulating layer. For this reason, by using water, alcohol, polyhydric alcohol, polyhydric alcohol alkyl ethers, amides, carbonyls as the solvent of the second solvent, the inorganic powder of the first insulating layer, the organic binder, Alternatively, the thickness of the region where the other constituent materials and the inorganic powder of the second slurry, the organic binder, or other constituent materials are mixed is reduced, and the thickness and concentration unevenness of the mixed regions are inevitably reduced. Therefore, as described above, the material characteristics after firing are stable, and deformation and cracks do not occur in the manufacturing process.

  Furthermore, in this embodiment, the solubility of the second organic binder in the second solvent is 5% or more. Specifically, acrylic resin, methacrylic resin, urethane resin, vinyl acetal resin, vinyl alcohol resin and the like are used. Vinyl alcohol resin is dissolved in the second solvent having a high SP value, but organic binders such as acrylic resin, methacrylic resin, urethane resin, and vinyl acetal resin are usually not dissolved in the second solvent as they are. Modified to dissolve in solvent. Modification is performed, for example, by adding a polar functional group such as a carboxyl group, a hydroxyl group, or an amine group to an acrylic resin, a methacrylic resin, a urethane resin, or a vinyl acetal resin, and the ratio of polar groups increases in the resin. It becomes soluble in the second solvent. Vinyl acetal resins are produced by condensation of vinyl alcohol resins and aldehydes, or saponification of esters of vinyl alcohol resins. These reactions are stopped halfway, and vinyl acetal resins are partially added to the vinyl acetal resins. By making the structure of the alcohol resin remain, it can be modified so as to be dissolved in the second solvent. Here, acrylic resin and methacrylic resin are preferable materials because they have good thermal decomposability, and among these, methacrylic acid resins are particularly preferable materials because they have particularly good thermal decomposability. Moreover, since addition of a polar functional group deteriorates the thermal decomposability of an organic binder, it is preferable to reduce the addition of a polar functional group.

  Next, a method for manufacturing a multilayer substrate using a composite ceramic green sheet according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  3 is a cross-sectional view of the multilayer ceramic substrate before lamination, in which 3a to 3c are composite ceramic green sheets, 1a to 1c are first insulating layers, 2a to 2c are second insulating layers, and 4 is a via hole. Conductors 5 are wiring conductors.

  4 is a cross-sectional view of the fired multilayer ceramic substrate, in which 11a to 11c are first insulating layers, 12a to 12c are second insulating layers, 14 are via-hole conductors, and 15 is a wiring conductor. A part of the outermost wiring conductor functions as a terminal for mounting a connection pad or a multilayer ceramic substrate as a mounting portion of an electronic component on another printed circuit board or the like. The wiring conductor and the via hole conductor electrically connect each circuit element. Further, some of the wiring conductors and via-hole conductors may function as circuit elements such as inductors, capacitors, filters, and the like.

  A composite ceramic green sheet 3 formed on the basis of the first embodiment is formed with a through hole by punching, laser, or the like, a conductive paste is filled in the through hole and dried to form a via-hole conductor 4, and the composite ceramic green sheet A wiring paste 5 is formed on the main surface by applying and drying a conductive paste by screen printing or the like.

  Examples of the material for the wiring conductor 4 and the via-hole conductor 5 include a paste formed by adding ethyl cellulose as an organic binder and 2-2-4-trimethyl-3-3-pentadiol monoisobutyrate as a solvent to silver powder. Used. When the baking temperature of the substrate is about 800 to 1000 ° C., conductors such as gold, silver, and copper are preferable conductor materials because of low conductor resistance. When the firing temperature of the substrate is about 1300 ° C. or less, a conductor such as silver palladium or nickel is used, and when the firing temperature is about 1500 ° C. or less, a conductor such as molybdenum or tungsten is used. The diameter of the via-hole conductor 4 can be arbitrarily set, but is set to 25 to 300 μm when the thickness of the composite ceramic green sheet 3 is 10 to 600 μm. The thickness of the wiring conductor 5 is set to 5 to 30 μm, for example. It should be noted that a cavity or an end surface through hole is formed by punching, laser, or the like as necessary.

  Next, the composite ceramic sheets 3a to 3c are stacked in a predetermined stacking order to form a stacked body. The laminated body is formed by applying and drying wiring conductors, terminal end electrodes for terminals, protective glass, and the like, if necessary, by screen printing or the like. Furthermore, a snap line is formed in the laminate as necessary, and the laminate is cut into a predetermined dimension.

  Subsequently, in the present embodiment, the laminate is fired at 900 ° C. At the initial stage of heating, the plasticizer is volatilized and debindered. Subsequently, sintering of the inorganic powder occurs. In this embodiment, the temperature at which the inorganic powders of the first insulating layers 1a to 1c and the insulating layers 2 of the second a to 2c start shrinking is different by 80 ° C., and sintering while suppressing the shrinking behavior of each other, Shrinkage in the plane direction during firing is reduced.

During the manufacturing process of the multilayer ceramic substrate described above, the composite ceramic green sheets 3a to 3c are subjected to stress such as processing stress and heat due to drying. However, the first insulating layers 1a to 1c and the second insulating layers 2a to 2c are applied. Since 2c is in close contact and a strong bond is obtained, it does not peel off during the process. Further, the area where the organic binder is mixed is small and uniform. As a result, there is no local variation in the strength, ease of deformation, density, etc. of the composite ceramic green sheet, and stresses generated in the composite ceramic green sheets 3a to 3c and uneven debonding due to variations in these characteristics. Therefore, no deformation or cracking occurs. Furthermore, when an insulating layer having a temperature at which shrinkage starts is different by 20 ° C. or more, or an insulating layer having a thermal expansion coefficient different by 0.5 × 10 ⁻⁶ or more is joined and sintered, a large stress is generated between the insulating layers. Occurs and peeling may occur. In this embodiment, peeling does not occur because the inorganic powder of each insulating layer is in close contact.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible within the range which does not deviate from the summary of this invention.

  For example, on the composite ceramic green sheet 3, a third slurry composed of a third inorganic powder, a third organic binder, and a third solvent is applied and dried to form a third insulating layer. A composite ceramic green sheet composed of multiple insulating layers may be formed. At this time, the solubility of the second organic binder in the third solvent is set to 2% or less, and the second inorganic powder and the third inorganic powder present near the interface between the second insulating layer and the third insulating layer. The composite ceramic green sheet has a thickness of 0.3 to 8 μm in a region where the inorganic powder is mixed and / or a region where the second organic binder and the third organic binder are mixed.

  Further, by appropriately designing each organic binder and the solvent, the first organic binder and the third organic binder, and the first solvent and the third solvent can be made the same. It is preferable to use the same material because the manufacturing conditions for forming each layer can be made common and restrictions on the binder removal conditions during firing are reduced.

  Furthermore, the first inorganic powder and the third inorganic powder may be the same. This configuration is preferable because a portion to be joined before firing becomes the same inorganic powder, and stress during firing due to different materials does not occur at the interface. Further, in this configuration, since the inorganic powder to be bonded to the conductor is one type, an inorganic powder that is difficult to bond to the conductor can be used as the second inorganic powder, which is preferable.

  Furthermore, in the above-described embodiment, a composite ceramic green sheet in which all the green sheets have the same layer structure is used, but the present invention is not limited to this. For example, a single-layer green sheet made of a single insulating layer or a composite ceramic green sheet having the three-layer structure described above may be combined and laminated. In this way, by using a green sheet having a different type of layer structure, the laminated body can have a layer structure symmetrical in the thickness direction. By using a symmetric layer structure in the thickness direction, it is possible to eliminate warping of the substrate even if the shrinkage behavior and thermal expansion coefficient of each layer are different.

  Furthermore, a wiring conductor may be formed on the insulating layer 1, and a second slurry may be applied and dried thereon to produce a composite ceramic green sheet including the wiring conductor. According to this configuration, peeling due to a difference in thickness between a portion with wiring and a portion without wiring can be prevented.

It is sectional drawing of the composite ceramic green sheet by this invention. It is sectional drawing of the manufacturing process of the composite ceramic green sheet by this invention. It is sectional drawing before lamination | stacking of the multilayer ceramic substrate by this invention. 1 is a cross-sectional view of a multilayer ceramic substrate according to the present invention. It is a schematic diagram of the cross section of interface vicinity of the two insulating layers of the composite ceramic green sheet by this invention. It is a schematic diagram of the cross section of the interface vicinity of the two insulating layers of the conventional composite ceramic green sheet. It is a schematic diagram of the cross section of the interface vicinity of the two insulating layers of the conventional composite ceramic green sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st insulating layer 1a-c ... 1st insulating layer 2 ... 2nd insulating layer 2a-c ... 2nd insulating layer 3 ... Composite ceramic green sheet 3a- c ... composite ceramic green sheet 4 ... via-hole conductor 5 ... wiring conductor 6 ... first slurry 7 ... second slurry 8 ... support film 9 ... doctor blade 10 ..Multilayer ceramic substrates 11a-c ... first insulating layers 12a-c ... second insulating layer 14 ... via hole conductor 15 ... wiring conductor 21 ... first inorganic powder 22 .. second inorganic powder 31... First organic binder 32... Second organic binder 33... Binder 41 mixed with first organic binder and second organic binder. A region 42 composed of only the insulating layer component of the second insulating layer Region 43 composed only of layer components. Region 51 where components of the first insulating layer and components of the second insulating layer coexist. 51… composed of only the components of the first insulating layer. Region 52... Region 53 composed of only the second insulating layer component 53... Region 51 where the first insulating layer component and the second insulating layer component coexist 51. Area 62 composed only of layer components ... Area 63 composed only of components of the second insulating layer ... Mixture of components of the first insulating layer and components of the second insulating layer region

Claims (6)

A composite in which a second insulating layer is formed by applying and drying a slurry containing the second inorganic powder and the second organic binder on the first insulating layer made of the first inorganic powder and the first organic binder. In ceramic green sheet,
In the vicinity of the interface between the first insulating layer and the second insulating layer, a region where the first inorganic powder and the second inorganic powder are mixed, and / or the first organic binder and the second A composite ceramic green sheet having a region in which organic binders are mixed and having a thickness of the mixed region of 0.3 to 8 μm. The first inorganic powder, the second organic powder, the second organic powder, and the second organic powder are formed on the first insulating layer formed by applying and drying the first slurry composed of the first inorganic powder, the first organic binder, and the first solvent in layers. In a method for producing a composite ceramic green sheet, a second slurry comprising a binder and a second solvent is applied in layers and dried to form a second insulating layer.
The method for producing a composite ceramic green sheet, wherein the solubility of the first organic binder in the second solvent is 2% or less. The method for producing a composite ceramic green sheet according to claim 2, wherein the solubility of the second organic binder in the second solvent is 5% or more. The method for producing a composite ceramic green sheet according to claim 2, wherein a solubility parameter (SP value) of the second solvent is 11 or more. 3. The composite ceramic green sheet according to claim 2, wherein the second solvent is water, alcohol, polyhydric alcohol, polyhydric alcohol alkyl ethers, amides, carbonyls or a mixed solvent thereof. Method. A wiring conductor constituting a circuit is formed on the composite ceramic green sheet according to any one of claims 1 to 5, a via-hole conductor penetrating the sheet is formed in a thickness direction, and a plurality of the composite ceramic green sheets are laminated, Then, the manufacturing method of the multilayer ceramic substrate which bakes the said laminated body.

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