JP4687333B2 - Multilayer ceramic substrate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a multilayer ceramic substrate having a cavity and a method of manufacturing the same, and in particular, a multilayer ceramic substrate having a conductor film positioned so as to extend from above the bottom surface of the cavity to the inside of the laminate along the bottom surface. It relates to the manufacturing method.

  Japanese Unexamined Patent Publication No. 2000-25157 (Patent Document 1) discloses a multilayer ceramic substrate 1 having a structure as shown in FIG. The multilayer ceramic substrate 1 is manufactured by applying a so-called non-shrinkage process in which shrinkage in a firing step performed when manufacturing the multilayer ceramic substrate 1 is suppressed.

  More specifically, the multilayer ceramic substrate 1 includes a plurality of laminated base material layers 2 each including an aggregate of a first powder containing a glass material and a first ceramic material, and at least one of the main layers. Having an aggregate of second powders including a second ceramic material that is positioned so that the surface is in contact with the base material layer 2 and that does not sinter at a temperature at which at least a portion of the first powder can be sintered. The laminated body 5 which has the laminated structure which consists of the constrained layer 3 comprised and the conductor film 4 formed so that it may extend in the main surface direction of the base material layer 2 is provided. In addition, about the conductor film 4, only what is needed in order to demonstrate the subject which this invention tends to solve is shown in figure, and illustration is abbreviate | omitted about another thing. Although not shown in FIG. 15, the multilayer ceramic substrate 1 normally includes a via-hole conductor that is electrically connected to a specific conductor film and provided so as to penetrate the specific base material layer 2 in the thickness direction. .

  The multilayer body 5 provided in the multilayer ceramic substrate 1 is provided with a cavity 6 having an opening on one end side in the stacking direction. The cavity 6 is provided to meet the demand for downsizing and lowering the height of an electronic component constituted by the multilayer ceramic substrate 1. Although not shown, the cavity 6 is provided with a semiconductor element, a chip component, or the like. Other electronic components are mounted.

  In the multilayer ceramic substrate 1, at least a part of the first powder included in the base material layer 2 is in a sintered state. On the other hand, the second powder contained in the constraining layer is in an unsintered state, but a part of the first powder containing the glass material is fixed to each other by diffusing or flowing into the constraining layer 3. Yes.

  In order to manufacture such a multilayer ceramic substrate 1, a laminate 5 in a raw state is produced, and then this raw laminate 5 is fired. In this firing step, at least a part of the first powder is sintered. In this firing step, part of the first powder, typically part of the glass material contained in the first powder, diffuses or flows into the constraining layer 3. As a result, the second powder is not sintered, but is fixed to each other by a part of the first powder, particularly a glass material.

  According to the manufacturing method as described above, since the second powder is not sintered in the firing step, the constraining layer 3 including the second powder acts to suppress the shrinkage of the base material layer 2. The shrinkage of the multilayer ceramic substrate 1 as a whole due to firing can be suppressed, and as a result, variation in the dimensions of the obtained multilayer ceramic substrate 1 can be reduced or unwanted deformation can be prevented. Can do. Further, in the obtained multilayer ceramic substrate 1, the second powder contained in the constraining layer 3 is fixed to each other as a part of the first powder containing the glass material diffuses or flows into the constraining layer 3. Therefore, it is not necessary to remove the constraining layer 3 later.

  FIG. 16 shows an enlarged part of the side surface 7 of the multilayer ceramic substrate 1. As shown in FIG. 16, irregularities are formed on the side surface 7 of the multilayer ceramic substrate 1. More specifically, a recess is formed on the end surface of the base material layer 2. This is because the shrinkage suppression force by the constraining layer 3 decreases as the distance from the constraining layer 3 increases. Note that the unevenness on the side surface 7 is illustrated only in FIG. 16, and in other drawings, such unevenness is not illustrated, and the side surface 7 is illustrated as a flat surface.

  Refer to FIG. 15 again. The conductor film 4 illustrated in FIG. 15 is formed on the bottom surface 8 of the cavity 6. The conductor film 4 is laminated along the boundary surface between the cavity bottom wall portion 9 defining the bottom surface 8 of the cavity 6 and the cavity side wall portion 11 defining the side surface 10 of the cavity 6 from the bottom surface 8 of the cavity 6. 5 so as to extend into the interior of 5.

  The constraining layer 3 in contact with the conductor film 4 described above is located on the boundary surface between the cavity bottom wall portion 9 and the cavity side wall portion 11. When the laminated body 5 in which the cavity 6 is formed is fired, shrinkage stress tends to concentrate on the boundary surface between the cavity bottom wall portion 9 and the cavity side wall portion 11, and cracks may occur in this boundary surface. The constraining layer 3 located on the boundary surface described above also acts to relieve the shrinkage stress and suppress the generation of cracks.

  However, the conductor film 4 located on the boundary surface between the cavity bottom wall portion 9 and the cavity sidewall portion 11 tends to be disconnected near the side surface 10 of the cavity 6. The cause will be described with reference to FIG. FIG. 17A is an enlarged view showing a portion A of FIG. 15 which is a portion located on the bottom surface of the cavity 6 in the conductor film 4, and FIG. It is a figure which expands and shows the part B of FIG. 15, which is a part located in the inside.

  The disconnection of the conductor film 4 described above may greatly differ between the environment affecting the portion shown in FIG. 17A and the environment affecting the portion shown in FIG. Responsible. That is, in the portion shown in FIG. 17A, the constraining layer 3 is located under the conductor film 4, and the conductor film 4 is an open space. On the other hand, in the portion shown in FIG. 17B, the constraining layer 3 is similarly below the conductor film 4, but the base material layer 2 is located on the conductor film 4. In the firing step, the glass material from the base material layer 2 permeates into the constraining layer 3, but the glass material permeates into a portion that does not originally contain the glass component, so that the glass component is small. On the other hand, the base material layer 2 originally contains abundant glass components to such an extent that the glass material can penetrate into the constraining layer 3 therefrom. Of course, there is no glass component in the open space.

  In the firing step, (1) softening of the glass in the base material layer 2, (2) penetration of the glass into the conductor film 4, (3) penetration of the glass into the constraining layer 3, and (4) the conductor film from the constraining layer 3 It is considered that sintering of the laminated body 5 proceeds in the order of glass permeation into 4. Here, (2) and (3) may occur almost simultaneously, but obviously (2) occurs before (4).

  In the part shown in FIG. 17B, the conductor film 4 is in close contact with the base material layer 2 and starts sintering at a relatively early stage according to the above (2). On the other hand, since the above (4) occurs at the latest stage, glass penetration has not yet occurred in the portion of the conductor film 4 shown in FIG. Yui hasn't happened yet. For this reason, in the portion shown in FIG. 17A, the conductor film 4 has a low density and is easily peeled off. In this state, when sintering is started at the portion shown in FIG. 17B in the conductor film 4, the conductor film 4 in FIG. Pull the part shown in. However, in the portion shown in FIG. 17A, since the sintering has not started and the adhesive force with the constraining layer 3 is insufficient, the conductor film 4 is torn near the side surface 10 of the cavity 6. As a result, disconnection occurs.

The problem of the disconnection of the conductor film 4 as described above tends to occur more easily as the shrinkage of the base material layer 2 in the firing process for obtaining the multilayer ceramic substrate 1 is further suppressed. Even when the layer 3 is formed only along the boundary surface between the cavity bottom wall portion 9 and the cavity sidewall portion 11, the problem of disconnection of the conductor film 4 is more or less encountered.
JP 2000-25157 A

  Accordingly, an object of the present invention is to provide a multilayer ceramic substrate and a method for manufacturing the same, which can solve the above-described problems.

  A multilayer ceramic substrate according to the present invention includes a plurality of laminated base material layers each including an aggregate of a first powder containing a glass material and a first ceramic material, and at least one main surface thereof being a base. An aggregate of second powders including a second ceramic material that is positioned in contact with at least one of the material layers and that does not sinter at a temperature at which at least a portion of the first powder can be sintered; A laminated body having a laminated structure composed of a constraining layer and a conductor film formed to extend in the main surface direction of the base material layer is provided.

  At least a part of the first powder is in a sintered state. On the other hand, although the second powder is in an unsintered state, a part of the first powder containing the glass material is fixed to each other by diffusing or flowing into the constraining layer.

  The laminate is provided with a cavity having an opening on one end side in the lamination direction. The conductor film described above includes a bottom conductor film formed on the bottom surface of the cavity. The bottom conductor film is positioned so as to extend from above the bottom surface of the cavity along the boundary surface between the cavity bottom wall portion that defines the bottom surface of the cavity and the cavity sidewall portion that defines the side surface of the cavity into the multilayer body. .

  The constraining layer described above includes a bottom surface constraining layer positioned between the bottom surface conductor film and the base material layer. The bottom surface constraining layer is formed so as to sandwich the bottom surface conductor film in the thickness direction inside the multilayer body.

  In the multilayer ceramic substrate according to the present invention, the constraining layer may include a second constraining layer other than the bottom constraining layer. In this case, the second constraining layer is positioned so as to form the outermost layer of the stacked body even if the second constraining layer includes those positioned inside the cavity bottom wall portion and / or cavity side wall portion of the stacked body. May be included. In either case, the thickness of the bottom constraining layer is preferably thinner than the thickness of the second constraining layer.

  In the multilayer ceramic substrate according to the present invention, the cavity includes a stepped portion at an intermediate portion in the stacking direction, and the conductor film includes a stepped conductor film formed on the stepped portion, and the stepped conductor film May extend from the stepped portion into the laminated body. In this case, the constraining layer includes a step constraining layer positioned between the step conductor film and the base material layer, and the step constraining layer has a thickness of the step conductor film inside the laminate. It is formed so as to be sandwiched in the direction.

  In the multilayer ceramic substrate according to the present invention, it is preferable that the second powder constituting the constraining layer is mainly composed of zirconia.

  The present invention is also directed to a method for manufacturing a multilayer ceramic substrate. The method for manufacturing a multilayer ceramic substrate according to the present invention includes a laminate manufacturing process and a firing process.

  In the laminate manufacturing step, the substrate in a raw state includes a glass material or a first powder containing a glass component that can be converted into a glass material by vitrification by firing and a first ceramic material. And a second ceramic material that is positioned so that at least one main surface thereof is in contact with at least one layer of the base material layer and does not sinter at a temperature at which at least a part of the first powder can be sintered. A laminated body having a laminated structure including a constraining layer in a raw state including a second powder and a conductor film formed so as to extend in a main surface direction of the base material layer, A cavity having an opening at one end in the stacking direction is provided, and the conductor film includes a bottom conductor film formed on the bottom surface of the cavity, and the bottom conductor film defines the bottom surface of the cavity from the bottom surface of the cavity. Do The constraining layer is positioned between the bottom conductor film and the base material layer, and is positioned to extend into the laminate along the boundary surface between the cavity bottom wall portion and the cavity side wall portion that defines the side surface of the cavity. The raw constraining layer is formed in such a manner that the bottom constraining layer is formed so as to sandwich the bottom conductor film in the thickness direction inside the multilayer body.

  Next, in the firing step, at least a part of the first powder is sintered, and a part of the first powder containing the glass material is diffused or flown into the constraining layer, whereby the second powder. The green laminate is fired at a predetermined temperature so that the bodies are fixed to each other without being sintered.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, the raw laminate may include a surface shrinkage suppression layer formed on at least one main surface and having substantially the same composition as the constraining layer. In this case, after the firing step, a step of removing the unsintered surface shrinkage suppression layer is further performed.

  According to the present invention, the bottom conductor film positioned so as to extend from the bottom surface of the cavity to the inside of the multilayer body is in contact with the bottom constraining layer positioned between this and the base material layer. However, since the inside of the laminated body is sandwiched in the thickness direction by the bottom surface constraining layer, the bottom surface of the cavity in the bottom surface conductor film is about the path of penetration of the glass material from the base material layer to the conductor film. Regardless of the part located above or the part located inside the laminate, the base layer passes through the bottom constraining layer and reaches the bottom conductor film. Therefore, the timing of the penetration of the glass material into the bottom conductor film can be substantially the same between the portion located on the bottom surface of the cavity and the portion located inside the laminate, and hence the sintering The timing can be substantially the same between the portion located on the bottom surface of the cavity and the portion located inside the stacked body. As a result, it is possible to make it difficult for disconnection to occur in the bottom conductor film.

  The multilayer ceramic substrate is positioned as a constraining layer, for example, inside the cavity bottom wall portion and / or cavity side wall portion of the laminate, or positioned to form the outermost layer of the laminate. In the case where the second constraining layer other than the bottom constraining layer is provided, if no measures are taken, the bottom conductor film is more likely to be disconnected, and the effect of the present invention is more remarkable. To be demonstrated.

  In the multilayer ceramic substrate according to the present invention, when the second powder constituting the constraining layer is mainly composed of zirconia, the bottom conductor film after the firing step is thinned in the vicinity of the side surface of the cavity. Can be reduced.

  In the multilayer ceramic substrate according to the present invention, when the cavity forms a stepped portion and a stepped conductor film extending from the stepped portion to the inside of the laminate is formed, the stepped conductor film and the base material layer If the step constraining layer positioned between the two is formed so as to sandwich the step conductor film in the thickness direction inside the multilayer body, this principle is the same as the case of the bottom conductor film described above. It can be made hard to produce this also about the disconnection in a step part conductor film.

  When the thickness of the bottom surface constraining layer is made thinner than the thickness of the second constraining layer, when the bottom surface constraining layer is formed so as to sandwich the bottom surface conductor film in the thickness direction, two bottom surface constraining layers are formed around the bottom surface conductor film. Even if formed to be heavy, the bottom constraining layer can be prevented from becoming too thick in this double portion. Therefore, the glass material can be sufficiently permeated into the double portion, and it is easy to form the bottom constraining layer densely as a whole.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, if the raw laminate has a surface shrinkage suppression layer that is removed after the firing step, the shrinkage suppression effect by the surface shrinkage suppression layer can be sufficiently expected. Some of the second constraining layers described above, which are located inside the cavity bottom wall part and inside the cavity side wall part, can be omitted.

  FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic substrate 21 according to the first embodiment of the present invention. FIG. 2 is an enlarged view of a portion C in FIG.

  The multilayer ceramic substrate 21 includes a plurality of stacked base material layers 22, a constraining layer 23 a positioned so that at least one main surface thereof is in contact with the base material layer 22, and a main surface direction of the base material layer 22. A laminated body 25 having a laminated structure including conductor films 24 and 24a formed to extend is provided. In addition, several via-hole conductors 26 are provided inside the laminate 25 so as to penetrate the specific base material layer 22 in the thickness direction while being electrically connected to specific ones of the conductor films 24 and 24a. It has been.

  The base material layer 22 is comprised with the aggregate | assembly of the 1st powder containing a glass material and a 1st ceramic material. For example, borosilicate glass is used as the glass material, and alumina is used as the first ceramic material.

  The constraining layer 23a is configured by an aggregate of second powders including a second ceramic material that is not sintered at a temperature at which at least a part of the first powder can be sintered. For example, zirconia or alumina is used as the second ceramic material, and zirconia is particularly preferably used.

  The conductor films 24 and 24a and the via-hole conductor film 26 are obtained by sintering a conductive paste. As a conductive component contained in the conductive paste, for example, Ag is used.

  At least a part of the first powder contained in the base material layer 22 is in a sintered state. On the other hand, the second powder contained in the constraining layer 23a is in an unsintered state, but a part of the first powder containing the glass material is fixed to each other by diffusing or flowing into the constraining layer 23a. ing.

  Further, the laminate 25 provided in the multilayer ceramic substrate 21 is provided with a cavity 27 having an opening at one end side in the lamination direction. Inside the cavity 27, as shown by an imaginary line, an electronic component 20 such as a semiconductor element or a chip component is accommodated and mounted.

  Of the conductor films 24 and 24 a described above, the conductor film 24 a is formed on the bottom surface 28 of the cavity 27. Therefore, the conductor film 24 a is referred to as a “bottom conductor film” in order to distinguish it from the other conductor films 24. The bottom conductor film 24 a is formed along the boundary surface between the cavity bottom wall portion 29 defining the bottom surface 28 of the cavity 27 and the cavity side wall portion 31 defining the side surface 30 of the cavity 27 from above the bottom surface 28 of the cavity 27. It is positioned to extend into the interior.

  The illustrated constraining layer 23 a forms the bottom surface of the cavity 27 and is positioned between the bottom surface conductor film 24 a and the base material layer 22. In this embodiment, a constraining layer other than the illustrated constraining layer 23a is not provided, but an embodiment in which a constraining layer other than the constraining layer 23a is provided (an embodiment described later, for example, an embodiment shown in FIG. 5) is considered. The constraining layer 23a as described above is referred to as a “bottom constraining layer” so that it can be distinguished from other constraining layers.

  The bottom constraining layer 23a is characterized in that the bottom conductor film 24a is sandwiched in the thickness direction inside the multilayer body 25, as well shown in FIG. Therefore, there is no portion where the bottom conductor film 24a is in direct contact with the base material layer 22, and the base layer 22 is always in a state in which the bottom constraining layer 23a is interposed.

  According to such a configuration, regarding the path of the penetration of the glass material from the base material layer 22 to the bottom conductor film 24a during firing, the portion of the bottom conductor film 24a located on the bottom surface 28 of the cavity 27 and the laminated body In any of the portions located inside 25, the base layer 22 passes through the bottom constraining layer 23a and reaches the bottom conductor film 24a. Therefore, the timing of penetration of the glass material into the bottom conductor film 24 a can be made substantially the same between the portion located on the bottom surface 28 of the cavity 27 and the portion located inside the multilayer body 25. Therefore, the timing of sintering can be substantially the same between the portion located on the bottom surface 28 of the cavity 27 and the portion located inside the stacked body 25. As a result, it is possible to make it difficult for disconnection to occur in the bottom conductor film 24a.

  The multilayer ceramic substrate 21 is manufactured as follows.

  First, the raw material of the laminate 25 shown in FIG. 1 is prepared. This raw laminate 25 includes a raw substrate layer 22, a raw bottom constraining layer 23a, a raw conductor film 24 and 24a, and a raw via-hole conductor. 26.

  The base material layer 22 in the raw state includes a glass material or a first powder containing a glass component that can be converted into a glass material by being melted and vitrified by firing, and a first ceramic material. As an example, the base material layer 22 in a raw state includes a borosilicate glass powder as a glass material, an alumina powder as a first ceramic material, water as a dispersion medium, and polyvinyl alcohol as a binder, And a polycarboxylic acid-based dispersant as a dispersant.

  The bottom surface constraining layer 23a in the raw state includes a second powder containing a second ceramic material that is not sintered at a temperature at which at least a part of the first powder can be sintered. As an example, the bottom constraining layer 23a in the raw state includes a zirconia powder as a second ceramic material, water as a dispersion medium, polyvinyl alcohol as a binder, and a polycarboxylic acid-based dispersant as a dispersant. Is included.

  The conductor films 24 and 24a and the via-hole conductor 26 in the raw state are made of a conductive paste. As an example, this conductive paste contains Ag powder, ethyl cellulose as a binder, and terpenes as a solvent.

  The raw laminate 25 is also provided with a cavity 27 having an opening at one end in the lamination direction. The bottom conductor film 24 a is positioned so as to extend from the bottom surface of the cavity 27 along the boundary surface between the cavity bottom wall portion 29 and the cavity side wall portion 31 into the multilayer body 25. In addition, the bottom surface constraining layer 23 a is formed between the bottom surface conductor film 24 a and the base material layer 22 so as to sandwich the bottom surface conductor film 24 a in the thickness direction inside the multilayer body 25.

  Next, the process of baking the raw laminated body 25 having the structure as described above is performed. Conditions such as the temperature applied in this firing step are selected so that the following state is obtained after the firing step.

  That is, as a result of the firing step, at least a part of the first powder included in the base material layer 22 is sintered. Moreover, a part of 1st powder containing the glass material contained in the base material layer 22 is spread | diffused or flows into the bottom face constrained layer 23a. Thereby, the second powder contained in the bottom surface constraining layer 23a is fixed to each other without being sintered.

  In the firing step described above, a part of the glass material contained in the base material layer 22 diffuses or flows throughout the bottom constraining layer 23a, and it is preferable that all of the second powders are fixed to each other. .

  In the firing step, since the second powder contained in the bottom constraining layer 23a is not sintered, the bottom constraining layer 23a is not substantially contracted. Therefore, the bottom surface constraining layer 23 a exerts a shrinkage suppressing action on the base material layer 22 and suppresses shrinkage in the main surface direction of the base material layer 22. From this, undesired deformation hardly occurs in the obtained multilayer ceramic substrate 21, and the dimensional accuracy can be improved. In particular, the bottom surface constraining layer 23 a is located along the boundary surface between the cavity bottom wall portion 29 and the cavity side wall portion 31. When the raw laminate 25 is fired, shrinkage stress tends to concentrate on the boundary surface between the cavity bottom wall portion 29 and the cavity side wall portion 31, and cracks are likely to occur on this boundary surface. The above-described bottom constraining layer 23a also acts to relieve the contraction stress and suppress the generation of cracks.

  FIGS. 3 and 4 are diagrams corresponding to FIG. 2 for explaining the second and third embodiments of the present invention, respectively. 3 and 4, elements corresponding to those shown in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  When attention is paid to the overlapping state of the bottom surface constraining layer 23a around the bottom surface conductor film 24a, in the first embodiment shown in FIG. 2, the lower bottom surface constraining layer 23a is flat and the upper bottom surface constraining layer 23a is the bottom surface. It is bent by the thickness of the conductor film 24a. In contrast, in the second embodiment shown in FIG. 3, the upper and lower bottom surface constraining layers 23a are bent by approximately half of the thickness of the bottom surface conductor film 24a. Whether the state shown in FIG. 2 is obtained or whether the state shown in FIG. 3 is obtained depends on the crimping conditions in the crimping step performed when the laminate 25 is made in a raw state. Dependent.

  In the third embodiment shown in FIG. 4, the bottom surface constraining layer 23a formed so as to sandwich the bottom surface conductor film 24a in the thickness direction inside the multilayer body 25 does not overlap around the bottom surface conductor film 24a. Is formed. That is, the bottom surface constraining layer 23a located on the bottom surface conductor film 24a is formed with substantially the same pattern as the bottom surface conductor film 24a. The bottom constraining layer 23a shown in FIG. 2 and FIG. 3 is formed by laminating green sheets for forming the bottom constraining layer 23a. At least on the bottom conductor film 24a of the bottom constraining layer 23a shown in FIG. What is positioned is formed by printing.

  FIG. 5 is a view corresponding to FIG. 1 for explaining a fourth embodiment of the present invention. In FIG. 5, like reference numerals are given to corresponding elements as shown in FIG.

  The multilayer ceramic substrate 21a shown in FIG. 5 includes a second constraining layer 23 other than the bottom constraining layer 23a as a constraining layer. The second constraining layer 23 is positioned inside the cavity bottom wall portion 29, positioned inside the cavity side wall portion 31, and positioned so as to form the outermost layer of the laminate 25. There is.

  According to the multilayer ceramic substrate 21a shown in FIG. 5, the second constraining layer 23 is newly provided as compared with the multilayer ceramic substrate 21 shown in FIG. The shrinkage-suppressing effect is enhanced, and the dimensional variation and undesired deformation of the multilayer ceramic substrate 21a can be made less likely to occur.

  The second constraining layer 23 is not provided along all the interfaces between the base material layers 22, but the constraining layers can be omitted at some interfaces.

  FIG. 6 is a view corresponding to FIG. 2 for explaining a fifth embodiment of the present invention. The fifth embodiment is a modification of the above-described fourth embodiment. In FIG. 6, elements corresponding to the elements shown in FIG.

  The fifth embodiment shown in FIG. 6 is characterized in that the bottom surface constraining layer 23 a is thinner than the second constraining layer 23. In the fourth embodiment shown in FIG. 5, the bottom surface constraining layer 23a and the second constraining layer 23 have the same thickness. Therefore, when the bottom surface constraining layer 23a is formed so as to sandwich the bottom surface conductor film 24a in the thickness direction, and the bottom surface constraining layer 23a is formed around the bottom surface conductor film 24a, the bottom surface The thickness is twice the thickness of one layer of the constraining layer 23a. For this reason, the double portion of the bottom surface constraining layer 23a cannot be sufficiently infiltrated with the glass material from the base material layer 22 in the firing step, and a dense structure may not be obtained. On the other hand, in the fifth embodiment shown in FIG. 6, the thickness of the bottom surface constraining layer 23a is made thinner than the thickness of the second constraining layer 23, for example, about half the thickness. Also in the double portion around 24 a, the bottom surface constraining layer 23 a is not so thick, and can have a thickness substantially equal to that of the second constraining layer 23. Accordingly, the glass material can be sufficiently permeated into the double portion, and the bottom constraining layer 23a can be easily formed densely as a whole.

  FIG. 7 is a view corresponding to FIG. 1 for explaining a sixth embodiment of the present invention. In FIG. 7, elements corresponding to those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  In the multilayer ceramic substrate 21b according to the sixth embodiment shown in FIG. 7, the cavity 27 forms a stepped portion 34 in the intermediate portion in the stacking direction. And the step part conductor film 24b formed on the step part 34 is provided as a conductor film. The stepped conductor film 24 b extends from above the stepped portion 34 to the inside of the multilayer body 25.

  The multilayer ceramic substrate 21b includes a stepped constraining layer 23b positioned between the stepped conductor film 24b and the base material layer 22 as a constraining layer. The step portion constraining layer 23b is formed inside the multilayer body 25 so as to sandwich the step portion conductor film 24b in the thickness direction. As described above, the step conductor film 24b has a configuration that surrounds the step conductor film 24b, which is substantially the same as that of the bottom conductor film 24a. Therefore, the step conductor film 24b is less likely to be disconnected by the same principle as that of the bottom conductor film 24a. can do.

  FIG. 8 is a view corresponding to FIG. 1 or FIG. 5 for explaining a seventh embodiment of the present invention. In FIG. 8, elements corresponding to the elements shown in FIG. 1 or 5 are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 8 shows a raw laminate 25a produced for manufacturing a multilayer ceramic substrate. The raw laminate 25a includes a surface shrinkage suppression layer 37 having substantially the same composition as the constraining layers 23 and 23a. In this embodiment, the surface shrinkage suppression layers 37 are formed on both main surfaces of the raw laminate 25a. The thickness of the surface shrinkage suppression layer 37 is made thicker than the thicknesses of the constraining layers 23 and 23a. Compared with the laminate 25 shown in FIG. 5, the second constrained layer 23 positioned so as to form the outermost layer of the laminate 25 shown in FIG. The surface shrinkage suppression layer 27 is formed instead.

  The surface shrinkage suppression layer 37 is removed after the step of firing the raw laminate 25a is finished. Since the surface shrinkage suppression layer 37 is in an unsintered state and has a relatively large thickness, the surface shrinkage suppression layer 37 is not densified by the penetration of the glass material contained in the base material layer 22, and thus can be easily removed. can do.

  If the raw laminate 25 a includes the surface shrinkage suppression layer 37, it is possible to sufficiently expect the shrinkage suppression effect during firing by the surface shrinkage suppression layer 37. Therefore, the inside of the cavity bottom wall portion 29 and the cavity side wall portion 31. It is also possible to omit some of the second constraining layers 23 located inside the. Therefore, when the surface shrinkage suppression layer 37 is applied in an embodiment that does not include the second constraining layer such as the multilayer ceramic substrate 21 shown in FIG.

  Next, experimental examples carried out to confirm the effects of the present invention will be described.

1. Preparation of Sample FIGS. 9 to 12 show a stacked structure of a raw laminate prepared to obtain a multilayer ceramic substrate as a sample manufactured in this experimental example. In the raw laminates 41a to 41d shown in FIG. 9 to FIG. 12, 42 indicates a base material layer, 43a indicates a bottom surface constraining layer, 43 indicates the other second constraining layer, and 44a indicates a bottom surface. Reference numeral 45 denotes a conductor film, 45 denotes a cavity, and 46 denotes a surface shrinkage suppression layer.

  About the green sheet which should become the base material layer 42, it produced as follows. That is, 60 parts by weight of borosilicate glass powder having an average particle size of about 4 μm, 40 parts by weight of alumina powder having an average particle size of 0.35 μm, 50 parts by weight of water as a dispersion medium, and 20 parts by weight of polyvinyl alcohol as a binder. And 1 part by weight of a polycarboxylic acid-based dispersant as a dispersant are mixed to form a slurry. After removing bubbles from the slurry, the slurry is formed into a sheet by the doctor blade method and dried. A green sheet having a thickness of 100 μm to be the material layer 42 was obtained.

  About the green sheet which should become each of the bottom face constrained layer 43a and the 2nd constrained layer 43, two types, the thing containing a zirconia powder and the thing containing an alumina powder, were produced as follows.

  That is, for those containing zirconia powder, 100 parts by weight of zirconia powder having an average particle size of 0.4 μm, 50 parts by weight of water as a dispersion medium, 20 parts by weight of polyvinyl alcohol as a binder, and polycarboxylic acid as a dispersant. 1 part by weight of an acid-based dispersant was mixed to form a slurry, and after removing bubbles from this slurry, the slurry was formed into a sheet by a doctor blade method and dried, whereby the constraining layers 43a and 43 having a thickness of 5 μm were formed. The green sheet which should become each was obtained.

  In addition, for those containing alumina powder, green sheets to be the respective constraining layers 43a and 43 having a thickness of 5 μm were obtained by the same method except that alumina powder was used instead of the zirconia powder. .

  As the conductive paste for forming the bottom conductor film 44a, a paste containing 48 parts by weight of Ag powder having an average particle diameter of 2 μm, 3 parts by weight of ethyl cellulose as a binder, and 49 parts by weight of terpenes as a solvent was prepared.

  The green sheet to be the surface shrinkage suppression layer 46 was produced as follows. That is, 100 parts by weight of alumina powder having an average particle size of 0.4 μm, 50 parts by weight of water as a dispersion medium, 20 parts by weight of polyvinyl alcohol as a binder, and 1 part by weight of a polycarboxylic acid-based dispersant as a dispersant The slurry was mixed to form a slurry, air bubbles were removed from the slurry, and then the slurry was formed into a sheet by a doctor blade method and dried to obtain a green sheet to be the surface shrinkage suppression layer 46 having a thickness of 200 μm.

  The following samples were prepared using these green sheets and the like.

(1) Sample 1
Sample 1 corresponds to an example within the scope of the present invention, and a raw laminate 41a having a laminate structure as shown in FIG. 9 was produced, and this was fired at a temperature of 850 ° C. for 2 hours. Next, it is obtained by removing the surface shrinkage suppression layer 46. In Sample 1, a green sheet containing zirconia powder was used as the green sheet to be the bottom constraining layer 43a.

(2) Sample 2
Sample 2 corresponds to an example within the scope of the present invention, and a raw laminate 41b having a laminate structure as shown in FIG. 10 was produced, and this was fired at a temperature of 850 ° C. for 2 hours. Next, it is obtained by removing the surface shrinkage suppression layer 46. In Sample 2, the green sheet that should serve as the bottom constraining layer 43a was one containing zirconia powder.

(3) Sample 3
Sample 3 corresponds to an embodiment within the scope of the present invention, and a raw laminated body 41b having a laminated structure as shown in FIG. 10 is produced and fired at a temperature of 850 ° C. for 2 hours. Then, the surface shrinkage suppression layer 46 is removed and obtained. In Sample 3, a green sheet that should be the bottom constraining layer 43a is one containing alumina powder.

(4) Sample 4
Sample 4 corresponds to an embodiment within the scope of the present invention, and a raw laminate 41c having a laminate structure as shown in FIG. 11 was produced and baked at a temperature of 850 ° C. for 2 hours. It is obtained. In sample 4, a green sheet containing zirconia powder was used as the green sheet to be the bottom constraining layer 43a.

(5) Sample 5
Sample 5 corresponds to a comparative example outside the scope of the present invention, and a raw laminated body 41d having a laminated structure as shown in FIG. 12 was produced, and this was fired at a temperature of 850 ° C. for 2 hours. Next, it is obtained by removing the surface shrinkage suppression layer 46. In sample 5, the green sheet that should serve as the bottom constraining layer 43a was one containing zirconia powder.

(6) Sample 6
Sample 6 corresponds to a comparative example outside the scope of the present invention, and a raw laminate 41d having a laminated structure as shown in FIG. 12 is laminated and fired at a temperature of 850 ° C. for 2 hours. Then, the surface shrinkage suppression layer 46 is removed and obtained. In the sample 6, a green sheet containing alumina powder was used as the green sheet to be the bottom constraining layer 43a.

2. Evaluation The multilayer ceramic substrate according to each of the samples 1 to 6 obtained as described above has an appearance as shown in FIG. FIG. 13 is a view showing the multilayer ceramic substrate 40 from the opening side of the cavity 45. 13, elements corresponding to those shown in FIGS. 9 to 12 are denoted by the same reference numerals. As shown in FIG. 13, the bottom conductor film 44 a formed on the bottom surface 47 of the cavity 45 intersects the side surface 48 of the cavity 45 at 40 points.

  For each of Samples 1 to 6, as shown in Table 1, the disconnection rate, the thinning rate, and the shrinkage rate were evaluated.

  The disconnection rate is determined that the multilayer ceramic substrate 40 is disconnected if at least one of the 40 intersections of the bottom surface conductor film 44a and the side surface 48 of the cavity 45 is disconnected. For each of the 15 multilayer ceramic substrates 40, the number of disconnected multilayer ceramic substrates 40, that is, the number of disconnected substrates, is determined, and the disconnection rate is determined based on the formula (number of disconnected substrates / 15) × 100 [%]. It is a thing.

  Regarding the reduction ratio, the multilayer ceramic substrate 40 is observed from the opening side of the cavity 45, and the width of the bottom conductor film 44a at the center of the bottom surface 47 of the cavity 45 is x as shown in FIG. The width at the narrowest portion in the vicinity of the intersection with the side surface 48 is y, and the width is obtained based on the formula {(xy) / x} × 100 [%]. The thinning ratios shown in Table 1 are obtained by averaging the measurement results in the vicinity of 40 intersections of the bottom surface conductor film 44a and the side surface 48 of the cavity 45 for each of the 15 multilayer ceramic substrates 40. .

  The shrinkage rate is obtained by measuring the shrinkage rate during firing for 15 multilayer ceramic substrates 40 and averaging them.

  As shown in Table 1, with respect to the shrinkage rate, no significant difference was observed between Samples 1 to 4 within the scope of the present invention and Samples 5 and 6 outside the scope of the present invention, but the disconnection rate. As for the thinning rate, Samples 1 to 4 within the scope of the present invention have significantly better results than Samples 5 and 6 outside the scope of the present invention.

  Further, when comparing samples 1 to 4 within the scope of the present invention, samples 1, 2, and 4 show better results than sample 3 in terms of the thinning rate. This is presumably because, in Samples 1, 2, and 4, green sheets containing zirconia powder were used as the green sheets to be the bottom constraining layer 43a.

1 is a cross-sectional view schematically showing a multilayer ceramic substrate 21 according to a first embodiment of the present invention. It is an enlarged view of the part C of FIG. It is a figure equivalent to FIG. 2 for demonstrating the 2nd Embodiment of this invention. It is a figure equivalent to FIG. 2 for demonstrating the 3rd Embodiment of this invention. It is a figure equivalent to FIG. 1 for demonstrating the 4th Embodiment of this invention. It is a figure equivalent to FIG. 2 for demonstrating 5th Embodiment of this invention. It is a figure equivalent to FIG. 1 for demonstrating the 6th Embodiment of this invention. It is for demonstrating 7th Embodiment of this invention, and is sectional drawing which shows the raw laminated body 25a schematically. In the experiment example implemented in order to confirm the effect by this invention, it is sectional drawing which shows the laminated structure which the raw laminated body 41a prepared in order to produce the sample 1 has. It is sectional drawing which shows the laminated structure which the raw laminated body 41b prepared in order to produce each of the samples 2 and 3 in the said experiment example has. It is sectional drawing which shows the laminated structure which the raw laminated body 41c prepared in order to produce the sample 4 in the said experiment example has. It is sectional drawing which shows the laminated structure which the raw laminated body 41d prepared in order to produce each of the samples 5 and 6 in the said experiment example has. It is a top view which shows the external appearance of the multilayer ceramic substrate 41 which concerns on each of the samples 1-6 produced in the said experiment example. It is an enlarged plan view of the bottom conductor film 44a for explaining the measuring method of the thinning rate evaluated in the experimental example. 1 is a cross-sectional view schematically showing a conventional multilayer ceramic substrate 1 of interest to the present invention. It is a figure which expands and shows a part of side surface 7 of the multilayer ceramic substrate 1 shown in FIG. (A) is the figure which expands and shows the part A of FIG. 15, (b) is a figure which expands and shows the part B in FIG.

Explanation of symbols

21, 21a, 21b Multilayer ceramic substrate 22 Base layer 23a Bottom constraining layer 23b Step constraining layer 23 Second constraining layer 24a Bottom conductor film 24b Step conductor film 24 Conductor film 25, 25a Laminate 27 Cavity 28 Bottom 29 Cavity Bottom wall part 31 Cavity side wall part 34 Step part 37 Surface shrinkage suppression layer

Claims (9)

A plurality of laminated base layers composed of an aggregate of first powders including a glass material and a first ceramic material;
A second ceramic material which is positioned so that at least one main surface thereof is in contact with at least one of the base material layers and which does not sinter at a temperature capable of sintering at least a part of the first powder. A constraining layer composed of an aggregate of second powders;
A laminated body having a laminated structure composed of a conductor film, which is formed so as to extend in the main surface direction of the base material layer,
At least a part of the first powder is in a sintered state,
The second powder is in an unsintered state, but a part of the first powder containing the glass material is fixed to each other by diffusing or flowing into the constraining layer,
The laminate is provided with a cavity having an opening on one end side in the laminating direction,
The conductor film includes a bottom conductor film formed on a bottom surface of the cavity, and the bottom conductor film defines a cavity bottom wall portion defining the bottom surface of the cavity and a side surface of the cavity from the bottom surface of the cavity. Positioned to extend into the stack along the interface with the cavity sidewall portion
The constraining layer includes a bottom surface constraining layer positioned between the bottom surface conductor film and the base material layer, and the bottom surface constraining layer sandwiches the bottom surface conductor film in the thickness direction inside the multilayer body. Formed in the
Multilayer ceramic substrate.   The multilayer ceramic substrate according to claim 1, wherein the constraining layer includes a second constraining layer other than the bottom surface constraining layer.   3. The multilayer ceramic substrate according to claim 2, wherein the second constraining layer includes one disposed inside the cavity bottom wall portion and / or the cavity side wall portion of the multilayer body.   The multilayer ceramic substrate according to claim 2, wherein the second constraining layer includes one positioned so as to form an outermost layer of the laminate.   The multilayer ceramic substrate according to claim 2, wherein a thickness of the bottom constraining layer is thinner than a thickness of the second constraining layer. The cavity has a stepped portion at an intermediate portion in the stacking direction, the conductor film includes a stepped conductor film formed on the stepped portion, and the stepped conductor film is formed on the stepped portion. To the inside of the laminate,
The constraining layer includes a step constraining layer positioned between the step conductor film and the base material layer, and the step constraining layer has a thickness of the step conductor film inside the multilayer body. Formed so as to sandwich in the direction,
The multilayer ceramic substrate according to any one of claims 1 to 5.   The multilayer ceramic substrate according to claim 1, wherein the second powder is mainly composed of zirconia. A raw material base layer comprising a glass material or a first powder containing a first ceramic material and a glass component that can be melted and vitrified by firing to become a glass material, and at least one of them A second powder comprising a second ceramic material, the main surface of which is positioned so as to be in contact with at least one layer of the base material layer, and which does not sinter at a temperature at which at least a part of the first powder can be sintered. Including a constrained layer in a raw state and a conductive film formed to extend in the main surface direction of the base material layer, and a laminate in one of the laminating directions. A cavity having an opening on the end side is provided, and the conductor film includes a bottom conductor film formed on a bottom surface of the cavity, and the bottom conductor film defines a bottom surface of the cavity from above the bottom surface of the cavity. The constraining layer is positioned to extend into the laminated body along a boundary surface between a cavity bottom wall portion and a cavity side wall portion defining a side surface of the cavity, and the constraining layer includes the bottom conductor film, the base material layer, A bottom constraining layer positioned between the base material and the bottom constraining layer is formed so as to sandwich the bottom conductor film in the thickness direction inside the multilayer body. And a laminate manufacturing process,
Sintering at least a part of the first powder, and diffusing or flowing a part of the first powder containing the glass material into the constraining layer, thereby allowing the second powder to A method for producing a multilayer ceramic substrate, comprising: a firing step of firing the raw laminates at a predetermined temperature so that they are fixed to each other without being sintered.   The raw laminate is provided with a surface shrinkage suppression layer formed on at least one main surface thereof and having substantially the same composition as the constraining layer, and after the firing step, the unsintered surface shrinkage suppression. The method for producing a multilayer ceramic substrate according to claim 8, further comprising a step of removing the layer.

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