JP2010251597A - Method of manufacturing multilayer ceramic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To planarize a surface of a part of substrate with a surface conductor formed thereon, in order to achieve low-profile and high functionality. <P>SOLUTION: The method of manufacturing the multilayer ceramic substrate 30 includes: a step of forming an unsintered stacked body 10 with a base layer 20, constrained layers 40a, 40b arranged on at least one main surface of the base layer 20 and which can not be substantially sintered at the temperature where the base layer 20 is sintered, surface conductors 6a-6c formed at interfaces 3a, 3b between the base layer 20 and constrained layers 40a, 40b, dummy patterns 8a-8c formed on a main surface or inside opposite to the main surface of each constrained layer 40a, 40b in contact with the base layer 20 so as to cover a region where surface conductors 6a-6c are formed when perspectively seen from a stacking direction; and a step of compressing the stacked body 10. Surfaces of substrates 3a, 3b can be planarized by compressing surface conductors 6a-6c into the base layer 20, because a stronger pressure is applied in the stacking direction to a region with dummy patterns 8a-8c formed, therein than the other region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer ceramic substrate, and more particularly to a method for manufacturing a multilayer ceramic substrate by so-called non-shrinkage firing in which a constraining layer is disposed on the main surface of a base material layer that becomes a multilayer ceramic substrate after firing.

  With the recent development of information communication devices and car electronics, multilayer ceramic substrates used for them are required to have a low profile and high functionality. Here, it is effective to planarize the substrate surface as one of means for realizing a reduction in the height and functionality of the multilayer ceramic substrate.

  For example, as shown in FIG. 9, the surface conductor 6 has a surface 3a of the multilayer ceramic substrate 30 as shown in FIG. 10 as compared with the case where the surface conductor 6 protrudes from the surface 3a of the multilayer ceramic substrate 30 in a convex shape. If the surface 3a of the multilayer ceramic substrate 30 is flat, the thickness A of the multilayer ceramic substrate 30 can be reduced by the thickness of the surface conductor 6, and the height can be reduced.

  Further, the surface conductor 6 of FIG. 10 has a larger flat area B of the surface conductor 6 than the surface conductor 6 of FIG. 9, and the area capable of wire bonding can be increased. Thereby, many mounting components can be mounted on the surface 3 a of the multilayer ceramic substrate 30, and the functionality of the multilayer ceramic substrate 30 can be enhanced.

  Therefore, it is desirable that the surface conductor is embedded in the substrate surface and the substrate surface is made as flat as possible.

  By the way, in order to planarize the substrate surface, for example, a technique disclosed in Japanese Patent Laid-Open No. 9-249470 (Patent Document 1) can be used. Patent Document 1 discloses a technique in which a constraining layer having a smaller rate of change in thickness at the time of pressure bonding than that of a base material layer to be a multilayer ceramic substrate is disposed on both surfaces of the base material layer for pressure bonding. Thereby, even if there exists a part in which a conductor exists in the inside of a base material layer, it can prevent that a board | substrate surface protrudes in convex shape, and the flatness of the board | substrate surface is ensured.

  Patent Document 1 does not disclose that the surface conductor and the base material layer are fired simultaneously. However, if the technique of Patent Document 1 is used, the surface conductor is applied to the surface of the base material layer before pressing the constraining layer. Even when the surface conductor and the base material layer are simultaneously fired, the constraining layer with a small rate of change in thickness at the time of crimping works to push the surface conductor into the base material layer, and it is possible to improve the flatness of the substrate surface. It is thought that there is an effect.

JP-A-9-249470

  However, even by the method of Patent Document 1, it is difficult to flatten the surface of the substrate where the surface conductors that are raised in a convex shape are formed before pressure bonding. In this regard, if the rate of change in the thickness of the constraining layer is considerably reduced, the surface conductor can be pushed into the base material layer, but such a high density constraining layer may adversely affect the binder removal property of the base material layer. Because it is not practical.

  Accordingly, an object of the present invention is to provide a method for producing a multilayer ceramic substrate that can flatten the substrate surface even when the surface conductor and the substrate layer are simultaneously fired using various substrate layers and constrained layers. It is in.

  In order to solve the above problems, the multilayer ceramic substrate production method of the present invention first produces an unfired laminate. The unfired laminate is disposed on at least one main surface of the base material layer formed by laminating a plurality of unfired ceramic layers for the base material layer, and substantially at the sintering temperature of the base material layer. A constraining layer comprising a non-sintered unfired ceramic layer for constraining layer, a surface conductor formed at the interface between the base material layer and the constraining layer, a main surface of the constraining layer facing the main surface contacting the base material layer, and And / or a dummy pattern formed so as to substantially cover a region where the surface conductor is formed when projected from the stacking direction. Next, the laminate is pressed and fired at a temperature at which the base material layer is sintered, and then the constraining layer and the dummy pattern are removed to obtain a multilayer ceramic substrate.

  Here, when the dummy pattern is projected from the stacking direction, it is formed so as to substantially cover the region in which the surface conductor is formed when the dummy pattern has the same pattern shape as the surface conductor. In addition, the case where the dummy pattern is smaller than the surface conductor and does not cover a part of the surface conductor includes the case where the dummy pattern covers the surface conductor slightly larger than the surface conductor.

  Further, the dummy pattern is preferably formed so as to substantially cover only the region where the surface conductor is formed or the region where the surface conductor is formed and its periphery when projected from the stacking direction. .

  However, the dummy pattern here is formed in order to push the surface conductor into the base material layer, and for other purposes, the main surface of the constraining layer facing the main surface in contact with the base material layer and A pattern may be formed inside.

  In the method for producing a multilayer ceramic substrate of the present invention, it is preferable that the side surface of the multilayer body is fixed with a frame-shaped mold when the multilayer body is pressure-bonded.

  Moreover, in the manufacturing method of the multilayer ceramic substrate of this invention, it is preferable that the rate of thickness change at the time of crimping | bonding of a constraining layer is smaller than the rate of thickness change at the time of crimping | bonding of a base material layer.

  Moreover, it is preferable that the thickness change rate at the time of crimping | bonding a surface conductor is equal to or larger than the thickness change rate at the time of crimping | bonding of a base material layer.

  In the method for manufacturing a multilayer ceramic substrate of the present invention, it is preferable that the thickness change rate when the dummy pattern is pressed is equal to or smaller than the thickness change rate when the surface conductor is pressed.

  Furthermore, it is preferable that the thickness change rate when the dummy pattern is pressed is substantially the same as the thickness change rate when the surface conductor is pressed.

  In the method for manufacturing a multilayer ceramic substrate of the present invention, the dummy pattern is preferably made of the same material as the surface conductor.

  Here, the same material as the surface conductor refers to a conductive paste used when forming the surface conductor.

  In the method for producing a multilayer ceramic substrate of the present invention, it is preferable that the thickness change rate when the dummy pattern is pressed is substantially the same as the thickness change rate when the constraining layer is pressed.

  In the method for manufacturing a multilayer ceramic substrate of the present invention, the dummy pattern is preferably made of the same material as the constraining layer.

  Here, the same material as the constraining layer refers to a ceramic slurry used when forming the constraining layer.

  In the method for producing a multilayer ceramic substrate of the present invention, a dummy pattern is formed on the unfired ceramic layer for constraining layer, and further on the unfired ceramic layer for constraining layer on which the dummy pattern is formed. A fired ceramic layer is preferably formed.

  In the method for producing a multilayer ceramic substrate of the present invention, it is preferable that the surface conductor is once formed on the unfired ceramic layer for the constraining layer and transferred to the base material layer.

  According to the present invention, the constraining layer substantially covers the region where the surface conductor is formed when projected from the stacking direction on the main surface facing the main surface in contact with the base material layer and / or the inside thereof. Since the laminated body is pressure-bonded in a state where the dummy pattern is formed, the portion where the dummy pattern is formed is more strongly applied in the stacking direction than the other portions. Therefore, when the surface conductor is pushed into the base material layer at the time of pressure bonding, the portion of the substrate surface where the surface conductor is formed can be planarized. As a result, when various surface layers and constraining layers are used and the surface conductor and the substrate layer are fired at the same time, the multilayer ceramic substrate can be reduced in height and the flat area of the surface conductor can be expanded. The mounting area can be increased.

  In addition, when the dummy pattern is projected from the stacking direction, only the region where the surface conductor is formed, or the region where the surface conductor is formed and its surroundings are substantially covered. A pressure can be locally applied to a region where the surface conductor is formed, and the surface conductor can be pushed into the base material layer.

  Also, in the step of crimping the laminate, fixing the side surface of the laminate with a frame-shaped mold can prevent the unsintered laminate from extending in the plane direction during crimping, so it was added by a dummy pattern. The pressure can be reliably applied in the stacking direction.

  Also, if the rate of change in thickness of the constraining layer during pressure bonding is smaller than the rate of change in thickness of the base material layer during pressure bonding, the constraining layer is harder than the base material layer, so the surface conductor is closer to the base material layer than the constraining layer. Can be pushed into.

  In addition, according to the present invention, since the pressure is applied by the dummy pattern even when the thickness change rate during crimping of the surface conductor is equal to or greater than the thickness change rate during crimping of the base material layer, the surface conductor Can be pushed into the base material layer, and the flatness of the substrate surface can be secured.

  Further, when the thickness change rate at the time of crimping the dummy pattern is equal to or smaller than the thickness change rate at the time of crimping the surface conductor, the surface conductor can be pushed in because the dummy pattern is harder than the surface conductor.

  Also, if the thickness change rate at the time of crimping the dummy pattern is substantially the same as the thickness change rate at the time of crimping the surface conductor, the elongation rate in the planar direction at the time of crimping is the same, so the entire surface conductor Pressure by a dummy pattern can be applied.

  Also, if the dummy pattern is made of the same material as the surface conductor, the dummy pattern can be formed in the same process as the surface conductor formed on the base material layer, so that the flatness of the substrate surface can be improved without requiring new equipment. It can be secured.

  Further, when the thickness change rate at the time of pressure bonding of the dummy pattern is substantially the same as the thickness change rate at the time of pressure bonding of the constraining layer, the pressure applied by the dummy pattern at the time of pressure bonding is not dispersed in the constraining layer. Can exert a strong pressure on

  Further, when the dummy pattern is made of the same material as that of the constraining layer, the cost can be reduced as compared with the case where the same material as that of the surface conductor is used.

  Further, when the dummy pattern is formed on the unfired ceramic layer for the constraining layer, and the unfired ceramic layer for the constraining layer is further formed on the unfired ceramic layer for the constraining layer on which the dummy pattern is formed, the surface of the constraining layer, That is, since the surface of the laminate becomes flat, it is possible to apply pressure uniformly to the laminate surface during pressure bonding.

  Further, once the surface conductor is formed on the unfired ceramic layer for the constraining layer and transferred to the base material layer, the unfired ceramic layer for the constraining layer formed with the surface conductor and the unfired ceramic layer for the constraining layer formed with the dummy pattern; Therefore, if one sheet of the same sheet is further laminated, a dummy pattern can be easily formed, and the manufacturing process is not complicated.

It is a figure which shows the manufacturing process concerning Example 1 of this invention, and is a schematic sectional drawing which shows the state before lamination | stacking. It is a figure which shows the manufacturing process concerning Example 1 of this invention, and is a schematic top view which shows the state which projected the laminated body from the lamination direction. It is a figure which shows the manufacturing process concerning Example 1 of this invention, and is a schematic top view which shows the state which projected and looked at the laminated body different from FIG. 2 from the lamination direction. It is a figure which shows the manufacturing process concerning Example 1 of this invention, and is a schematic top view which shows the state which projected the laminated body different from FIG. It is a figure which shows the manufacturing process concerning Example 1 of this invention, and is a schematic sectional drawing which shows the state before producing the laminated body different from a figure. It is a figure which shows the manufacturing process concerning Example 1 of this invention, and is a figure which shows the state after crimping | compression-bonding. It is a schematic sectional drawing which shows the multilayer ceramic substrate produced by the manufacturing method concerning Example 1 of this invention. It is a figure which shows the manufacturing process concerning Example 3 of this invention, and is a schematic sectional drawing which shows the state before lamination | stacking. It is a figure for demonstrating the effect of this invention, and is a schematic sectional drawing which shows the state in which the surface conductor protruded convexly from the board | substrate surface. It is a figure for demonstrating the effect of this invention, and is a schematic sectional drawing which shows the state by which the surface conductor was pushed in to the board | substrate surface.

  Hereinafter, the manufacturing method of the multilayer ceramic substrate concerning the Example of this invention is demonstrated, referring FIGS.

  The multilayer ceramic substrate according to Example 1 is manufactured through the following steps (1) to (8).

(1) Preparation of the base layer for green ceramic layer _{First, CaO-SiO 2 -Al 2 O} 3 -B 2 O 3 system by mixing a glass powder and alumina powder, to produce a low-temperature sintering ceramic powder. Acrylic resin as a binder, a solvent, a dispersant, and a plasticizer are added to this low-temperature sintered ceramic powder and kneaded thoroughly. After uniform dispersion, defoaming is performed under reduced pressure to produce a slurry. To do.

  Next, this slurry is formed into a sheet on a carrier film by a casting method using a doctor blade. After drying this, it cuts so that a plane dimension may be set to 150 mm (square), and produces the unbaking ceramic layers 2a-2c for base material layers with a thickness of 190 micrometers as shown in FIG.

(2) Preparation of unfired ceramic layer for constrained layer Add butyral resin as binder, solvent, dispersant, and plasticizer to alumina powder, thoroughly knead and uniformly disperse, then remove under reduced pressure A slurry is prepared by foam treatment.

  Next, this slurry is formed into a sheet on a carrier film by a casting method using a doctor blade. After drying this, it cuts so that a plane dimension may be set to 150 mm (square), and produces the unbaking ceramic layers 4a-4d for constraining layers with a thickness of 150 micrometers as shown in FIG.

  Here, by using a butyral resin as the binder contained in the unfired ceramic layers 4a to 4d for the constraining layer, the thickness change at the time of pressure bonding than the unfired ceramic layers 2a to 2c for the base material layer using the acrylic resin as the binder The rate can be reduced, i.e. hardened. In order to reduce the rate of change in thickness at the time of pressure bonding, in addition to changing the type of binder as described above, it can be realized by various methods such as reducing the amount of plasticizer and dispersant and increasing the density of alumina powder.

(3) Formation of surface conductor A desired conductor pattern is formed on the unfired ceramic layers 2a to 2c for the base material layer. As shown in FIG. 1, the interfaces 3a and 3b between the base material layer 20 made of the unfired ceramic layers 2a to 2c for the base material layer and the constraining layers 40a and 40b made of the unfired ceramic layers 4a to 4d for the constraining layers The surface conductors 6a to 6c having a desired pattern are formed.

  In order to form the surface conductors 6a to 6c, a conductive paste mainly composed of Ag, Cu, or the like is applied to the surface 3a of the unfired ceramic layer 2a for the base material layer as in the case of the surface conductor 6a by screen printing, inkjet, or the like. It can be applied directly by a method.

  Further, a conductor pattern is formed on the surface 5c of the constraining layer unfired ceramic layer 4c in contact with the unfired ceramic layer 2c for the base material by the same method as the surface conductors 6b and 6c, and this is used for the base material layer. The surface conductors 6b and 6c can be transferred to the interface 3b by laminating and pressing with the unfired ceramic layer 2c.

  Although omitted in FIG. 1, interlayer connection conductors and in-plane conductors having a desired pattern are formed on the unfired ceramic layers 2a to 2c for the base material layer. The interlayer connection conductor is formed by forming a through hole with a laser or the like and filling the through hole with a conductive paste. The in-plane conductors are formed on the surfaces of the unfired ceramic layers 2a to 2c by a method such as screen printing or ink jet, similarly to the surface conductors 6a to 6c.

  Here, the in-plane conductor is formed at the interface between the unfired ceramic layers 2a and 2b for the base material layer and the interface between the unfired ceramic layers 2b and 2c for the base material layer. Formed at the interface 3a between the unfired ceramic layer 2a for the base material layer and the unfired ceramic layer 4b for the constrained layer and the interface 3b between the unfired ceramic layer 2c for the base material layer and the unfired ceramic layer 4c for the constraining layer It is.

(4) Formation of dummy pattern In Example 1, the dummy patterns 8a to 8c are formed only on the surfaces of the constraining layers 40a and 40b, only on the inside, or both on the surface and inside. For example, as shown in FIG. 1, dummy patterns 8a to 8c are formed on the surfaces 5a and 5d of the unfired ceramic layers 4b and 4d for the constraining layer.

  The dummy patterns 8a to 8c are formed so as to cover regions where the surface conductors 6a to 6c are formed when projected from the stacking direction. Specifically, it is preferable to form so as to cover only the region where the surface conductors 6a to 6c are formed. More specifically, it is preferable that the dummy patterns 8a to 8c have substantially the same pattern shape as the surface conductor. This is because a strong pressure is locally applied to a portion where the dummy patterns 8a to 8c are formed, that is, a region where the surface conductors 6a to 6c are formed in a crimping process described later. Here, “substantially the same” means that the surface conductors 6a to 6c and the dummy patterns 8a to 8c substantially coincide with each other when projected from the stacking direction, and as shown in FIG. 2, the surface conductors 6a to 6c. It means that there may be a part that protrudes. Moreover, as shown in FIG. 3, it means that the dummy patterns 8a to 8c may be smaller than the surface conductors 6a to 6c, and there may be portions that do not cover the surface conductors 6a to 6c. For example, substantially the same pattern shape can be realized by diverting the screen plate used for forming the surface conductors 6a to 6c to the formation of the dummy patterns 8a to 8c. In this case, since it is not necessary to manufacture a new screen plate or the like in order to form the dummy patterns 8a to 8c, the cost can be reduced.

  In addition, the shape of the dummy patterns 8a to 8c is not limited to the substantially same pattern shape as the surface conductors 6a to 6c, and can cover the region where the surface conductors 6a to 6c are formed. Good. For example, as shown in FIG. 4, when the surface conductors 6a to 6c are formed close to each other, the dummy patterns 8a to 8c may be formed so as to cover the plurality of surface conductors at a time. More specifically, the dummy pattern is preferably formed so as to cover only the region where the surface conductor is formed or the region where the surface conductor is formed and the periphery thereof.

  In the first embodiment, the dummy patterns 8a to 8c are made of the same conductive paste as the surface conductors 6a to 6c. In this case, since the dummy patterns 8a to 8c can be formed in the same manner in the facilities and processes for forming the surface conductors 6a to 6c on the unfired ceramic layer 2a for the base layer and the unfired ceramic layer 4c for the constraining layer, This is useful in that it is not necessary to introduce new equipment and processes to form the dummy patterns 8a to 8c.

(5) Production of Laminate The laminate 10 is produced by laminating the unfired ceramic layers 2a to 2c for the base layer and the unfired ceramic layers 4a to 4c for the constraining layer. More specifically, as shown in FIG. 1, the base layer 20 is produced by laminating three unfired ceramic layers 2a to 2c for the base layer, and both main surfaces 3a and 3b of the base layer 20 are formed. The constraining layers 40a and 40b are respectively disposed on the substrate.

  In producing the laminate 10, the green sheets produced by the above method may be laminated, or the unfired ceramic layers 2a to 2c for the base layer and the unfired ceramic layers 4a to 4d for the constraining layer may be formed. Each layer may be formed by printing.

  As shown in FIG. 1, it is preferable to produce a laminated body so that the dummy patterns 8a to 8c are located inside the constraining layers 40a and 40b. Specifically, a dummy pattern 8a is formed on the main surface 5a of the constraining layer unfired ceramic layer 4b that faces the main surface 5b that contacts the main surface 3a of the base material layer 20, and is further formed on the main surface 5a. The unfired ceramic layer 4a for the constraining layer is formed. Alternatively, like the unfired ceramic layer 4d for the constraining layer, the main surface 5d on which the dummy patterns 8b and 8c are formed is laminated toward the inner layer, so that the dummy patterns 8a to 8c are placed inside the constraining layers 40a and 40b. Can be formed.

  In this way, by forming the dummy patterns 8a to 8c only inside the constraining layers 40a and 40b, the outer surfaces of the constraining layers 40a and 40b, that is, the outer surface of the laminate 10 are flattened. The pressure can be uniformly applied to the laminate 10.

  As shown in the constraining layer unfired ceramic layers 4c and 4d in FIG. 1, once the surface conductors 6b and 6c are formed on the constraining layer unfired ceramic layer 4c and transferred to the base material layer 20, the surface conductor 6b is formed. , 6c and the constraining layer unfired ceramic layer 4c formed with the dummy patterns 8b and 8c are substantially the same, and therefore the constraining layer on which the surface conductor is formed. If one more unfired ceramic layer is laminated, a dummy pattern can be easily formed, and the manufacturing process is not complicated.

  Further, as shown in FIG. 5, the dummy patterns 8a to 8c are not inside the constraining layers 40a and 40b but on the main surface facing the main surface of the constraining layers 40a and 40b contacting the base material layer 20, that is, the outer surface. It may be formed. In this case, since the constraining layers 40a and 40b can each be formed by one unfired ceramic layer for constraining layers, the cost for the unfired ceramic layer for constraining layers can be reduced.

  The dummy patterns 8 a to 8 c may be formed on both the inside of the constraining layers 40 a and 40 b and the main surface facing the main surface in contact with the base material layer 20. However, it is necessary to be careful that the pressure applied to the surface conductors 6a to 6c is increased and the surface conductors 6a to 6c are not excessively recessed from the surfaces 3a and 3b of the base material layer 20.

(6) Crimping Next, the laminate 10 is crimped. At the time of this crimping, the portion where the dummy patterns 8a to 8c are formed is pressed more strongly in the stacking direction than the other portions, so that the surface conductors 6a to 6c can be pushed into the surface of the base material layer 20, The flatness of the substrate surface can be improved.

  In Example 1, as shown in FIG. 6, pressure is applied in the stacking direction in a state where the stacked body 10 is put in the mold 9. The mold 9 includes an upper part 9a, a frame-shaped side part 9b, and a lower part 9c. The frame-shaped side surface portion 9b fixes the side surface of the laminated body 10, so that the laminated body 10 can be prevented from extending in the plane direction at the time of pressure bonding. Therefore, the pressure applied by the dummy patterns 8a to 8c can be reliably applied in the stacking direction.

  Note that the frame-like side surface portion 9 b of the mold 9 is preferably slightly larger than the laminate 10. If there is a gap between the frame-shaped side surface portion 9b and the side surface of the laminated body 10, there is a margin when the laminated body 10 is put into the mold 9, and the end of the laminated body 10 is caught by the mold 9. It is because generation | occurrence | production of a burr | flash can be suppressed.

  Further, in the present invention, it is not always necessary to fix the side surface of the laminate 10 with a mold. For example, it is also possible to use a hydrostatic press that is placed in a water tank of a hydrostatic pressure press apparatus in a vacuum-packed state with a plastic bag as a packaging container and to which a hydrostatic pressure is applied. In the case of this hydrostatic press, it is possible to suppress the laminate 10 from extending in the plane direction during press bonding due to the hydrostatic pressure applied to the side surface. However, it is possible to surely prevent the laminate 10 from extending in the plane direction at the time of crimping by fixing the side surface of the laminate with the mold 9 rather than the hydrostatic pressure press, so the dummy patterns 8a to 8c. It is preferable in that the pressure applied by can be reliably applied in the stacking direction.

(7) Firing Next, the laminated body 10 is fired at a temperature at which the base material layer 20 is sintered. Specifically, when a low-temperature sintered ceramic material is used as the base material layer 20, firing is performed at 800 ° C. to 1050 ° C.

  Further, the constraining layers 40 a and 40 b arranged on both main surfaces of the base material layer 20 are not substantially sintered at the sintering temperature of the base material layer 20. Therefore, since the constraining layers 40a and 40b do not substantially contract in the firing step, the base material layer 20 in contact with the constraining layers 40a and 40b is substantially prevented from contracting in the plane direction and contracts only in the stacking direction. Thereby, the dimensional accuracy of the base material layer 20 can be improved.

  In the firing step, the laminate 10 need not be fired while being pressurized. When firing while applying pressure, the surface of the substrate can be flattened, but equipment for applying pressure is required, which is expensive. According to the manufacturing method of Example 1, even if the laminate 10 is baked without applying pressure, the flatness of the substrate surface can be improved.

(8) Removal of constraining layer and dummy pattern After firing, the constraining layers 40a and 40b and the dummy patterns 8a to 8c are removed, and the multilayer ceramic substrate 30 shown in FIG. 7 is taken out. Since the constraining layers 40a and 40b are not substantially sintered and are in a porous state, they can be easily removed by blasting or the like. Further, since the dummy patterns 8a to 8c are formed inside or on the outer surfaces of the constraining layers 40a and 40b, they can be removed together with the constraining layers 40a and 40b.

  In general, the glass contained in the base material layer 20 tends to soak in the vicinity of the surface conductor due to the diffusion of the metal contained in the conductive paste, and this glass is chemically combined with the ceramic powder constituting the constraining layers 40a and 40b. To form a reaction layer. This reaction layer is difficult to remove and tends to remain. In this respect, when the surface conductors 6a to 6c form convex portions, a contact layer between the surface conductors 6a to 6c and the constraining layers 40a and 40b is large, so that a reaction layer is likely to be generated, and the surface conductors 6a to 6c are not flat. It is difficult to remove the reaction layer on the side. However, according to the manufacturing method of Example 1, the surface conductors 6a to 6c are embedded in the base material layer 20, and the contact area between the surface conductors 6a to 6c and the constraining layers 40a and 40b is small. , 40b is improved.

(9) Evaluation Table 1 shows the results of measuring the unevenness of the surfaces 3a and 3b and the surface conductors 6a to 6c of the multilayer ceramic substrate 30 manufactured by the manufacturing method of Example 1 with a laser film thickness meter.

Sample 1 is a multilayer ceramic substrate 30 manufactured by the manufacturing method of Example 1 described above with reference to FIG. In Sample 1, the unfired ceramic layers 2a to 2c for the base layer are formed by laminating three green sheets having a thickness of 190 μm to form the base layer 20, and the unfired ceramic layers 4a to 4d for the constraining layer are formed on both main surfaces thereof. Two 150 μm green sheets were laminated. The thicknesses of the surface conductors 6a to 6c and the dummy patterns 8a to 8c are 18 μm. The pressure at the time of pressure bonding is 1800 kgf / cm ² . The surface 3b of the multilayer ceramic substrate 30 shown in FIG. 7 was measured.

  As a comparative example, Sample 2 is one in which constraining layers 40a and 40b are formed as unconstrained ceramic layers 4a and 4c for constraining layers without forming a dummy pattern.

  Further, in order to confirm that the difference in pressure between the sample 1 and the sample 2 is not caused by the difference in thickness between the constraining layers 40a and 40b, the constraining layers 40a and 40b as the sample 3 have the same thickness as the sample 1. The constraining layers 40a and 40b were each composed of two layers of unfired ceramic layers 4a and 4b, 4c and 4d for the constraining layer so that the number of the constraining layers 40a and 40b was increased. Note that a dummy pattern is not formed on the sample 3.

  In Samples 2 and 3, other conditions are the same as in Sample 1.

  As a result of the measurement, in the sample 1, the surface conductor did not form a convex portion with respect to the substrate surface, and the flatness of the substrate surface could be secured. Moreover, it was confirmed by the sample 3 that the effect of the sample 1 was caused not by the thickness of the constraining layer but by the dummy pattern.

  As an effect produced by the present invention, the fact that the substrate surface is flat is not necessarily limited to the case where the substrate surface is completely flat. As in sample 1 in Table 1, it is desirable that the surface conductor is embedded in the substrate surface to completely flatten the substrate surface. However, as an effect exhibited by the present invention, if the surface conductor thickness can be embedded about half. Good. This is because, as shown in Samples 2 and 3 in Table 1, about half the thickness of the surface conductor cannot be embedded unless the present invention is used.

  Next, Table 2 shows the relationship of the rate of change in thickness of each material used for the sample 1 during pressure bonding.

  Here, the thickness change rate at the time of pressure bonding is calculated by the following equation.

Thickness change rate during crimping = (thickness before crimping−thickness after crimping) / thickness before crimping × 100 (%)
From the sample 1 in Table 1, it can be confirmed that in the laminate in which the dummy pattern is formed, the surface conductor is pushed into the substrate surface, and the unevenness of the substrate surface due to the surface conductor can be eliminated.

  Further, from Samples 2 and 3 in Table 1, if a dummy pattern is not formed, more than half of the thickness of the surface conductor cannot be pushed into the surface of the base material layer, and the substrate surface is completely flattened. It can be confirmed that it is difficult to reach.

  Moreover, even if it is a case where the thickness change rate at the time of the crimping | bonding of a surface conductor is equivalent to or larger than the thickness change rate of a base material layer from the sample 1 and Table 2 of Table 1, the effect of this invention is acquired. Can be confirmed. In this regard, if the thickness change rate during pressure bonding of the surface conductor is smaller than the thickness change rate during pressure bonding of the base material layer, that is, if the surface conductor is harder than the base material layer, the surface conductor is It is thought that it is easy to be pushed into the material layer. On the other hand, according to the manufacturing method of Example 1, even when the surface conductor is difficult to be pushed into the base material layer, that is, when the surface electrode is not harder than the base material layer, the pressure is applied by the dummy pattern. Since it is added, the surface electrode can be pushed into the base material layer. Therefore, according to Example 1, it is not necessary to be concerned with the rate of change in thickness when the surface conductor, the base material layer, or the constraining layer is crimped, and the degree of freedom in selecting the material of the surface conductor or the material of the base material layer can be increased. it can.

  Steps (1) to (3) and (5) to (8) are the same as in Example 1.

(4) Formation of dummy pattern In Example 2, the same ceramic slurry as the constraining layer unfired ceramic layers 4a to 4d is used as the material of the dummy patterns 8a to 8c. Others are the same as in the first embodiment.

  In Example 1, the same conductive paste as the surface conductors 6a to 6c was used as the material of the dummy patterns 8a to 8c. However, as in Example 2, by using the same material as the constraining layers 40a and 40b, The following effects are obtained.

  First, since the ceramic slurry is cheaper than the conductive paste, the cost can be reduced. Further, since the rate of change in thickness when the constraining layers 40a and 40b and the dummy patterns 8a to 8c are bonded is the same, the pressure applied by the dummy patterns 8a to 8c during the pressing is not distributed to the constraining layers 40a and 40b. A strong pressure can be applied to the surface conductors 6a to 6c.

  Steps (1) to (3) and (6) to (8) are the same as those in Example 1.

(4) Formation of dummy pattern In Example 3, as shown in FIG. 8, dummy patterns 8a-8c are formed on carrier films 11a, 11b such as PET films. Others are the same as in the first embodiment.

(5) Production of Laminate Carrier films 11a and 11b are constrained layers 40a and 40b so that principal surfaces 15a and 15b on which dummy patterns 8a to 8c of carrier films 11a and 11b are formed are in contact with constraining layers 40a and 40b. Laminate. About others, it is the same as that of Example 1. FIG.

  When the dummy patterns 8a to 8c are formed on the carrier films 11a and 11b as in the third embodiment, there is no need to provide another unfired ceramic layer for constraining layers in order to form the dummy patterns 8a to 8c. Therefore, the amount of ceramic slurry used can be reduced. Moreover, since the outer surface of a laminated body becomes flat with the carrier films 11a and 11b, a pressure can be uniformly applied to the laminated body surface at the time of pressure bonding.

  In addition, in this invention, it is not limited to these Examples, A various laminated body can be produced using a various material as a dummy pattern.

2a, 2b, 2c Unfired ceramic layer for base layer 3a, 3b Main surface of substrate layer and substrate surface 4a, 4b, 4c, 4d Unfired ceramic layer for constraining layer 5a, 5b, 5c, 5d Unconstrained for constraining layer Surface of fired ceramic layer 6, 6a, 6b, 6c Surface conductor 8a, 8b, 8c Dummy pattern 9 Mold 10 Laminated body 11a, 11b Carrier film 15a, 15b Surface of carrier film 20 Base material layer 30 Multilayer ceramic substrate 40a, 40b Constrained layer

Claims (12)

A base material layer formed by laminating a plurality of unfired ceramic layers for the base material layer;
A constraining layer composed of an unsintered ceramic layer for constraining layers that is disposed on at least one main surface of the base material layer and is not substantially sintered at the sintering temperature of the base material layer;
A surface conductor formed at the interface between the base material layer and the constraining layer;
The constraining layer is formed on the main surface facing the main surface in contact with the base material layer and / or inside, and substantially covers the region where the surface conductor is formed when projected from the stacking direction. A dummy pattern formed on
Producing an unfired laminate having
Crimping the laminate; and
Firing the laminate at a temperature at which the substrate layer sinters;
Removing the constraining layer and the dummy pattern;
A method for producing a multilayer ceramic substrate comprising:   The dummy pattern is formed so as to substantially cover only a region where the surface conductor is formed or a region where the surface conductor is formed and its periphery when projected from the stacking direction. 2. A method for producing a multilayer ceramic substrate according to 1.   The method for manufacturing a multilayer ceramic substrate according to claim 1 or 2, wherein, in the step of pressure-bonding the laminate, the side surface of the laminate is fixed with a frame-shaped mold.   The method for manufacturing a multilayer ceramic substrate according to any one of claims 1 to 3, wherein a rate of change in thickness of the constraining layer during pressure bonding is smaller than a rate of change in thickness of the base material layer during pressure bonding.   5. The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein a thickness change rate when the surface conductor is pressed is equal to or greater than a thickness change rate when the base material layer is pressed.   The method for manufacturing a multilayer ceramic substrate according to any one of claims 1 to 5, wherein a rate of change in thickness of the dummy pattern during crimping is equal to or less than a rate of change in thickness of the surface conductor during crimping.   The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein a thickness change rate when the dummy pattern is pressed is substantially the same as a thickness change rate when the surface conductor is pressed.   The method for manufacturing a multilayer ceramic substrate according to claim 7, wherein the dummy pattern is made of the same material as the surface conductor.   The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein a thickness change rate when the dummy pattern is pressed is substantially the same as a thickness change rate when the constraining layer is pressed.   The method for manufacturing a multilayer ceramic substrate according to claim 9, wherein the dummy pattern is made of the same material as the constraining layer.   The dummy pattern is formed on the unfired ceramic layer for the constraining layer, and the unfired ceramic layer for the constraining layer is further formed on the unfired ceramic layer for the constraining layer on which the dummy pattern is formed, The method for producing a multilayer ceramic substrate according to claim 1.   The method for producing a multilayer ceramic substrate according to claim 1, wherein the surface conductor is once formed on the unfired ceramic layer for the constraining layer and transferred to the base material layer.

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