JP4958509B2 - Ceramic multilayer substrate with cavity and method for manufacturing the same - Google Patents

Description

  The present invention relates to a ceramic multilayer substrate having a cavity in which an electronic component is disposed, and a method for manufacturing such a ceramic multilayer substrate with a cavity.

  A ceramic multilayer substrate produced by pressing and firing a ceramic green sheet laminate is suitable for increasing the density of a circuit because a wiring pattern or the like can be provided not only on the surface layer but also between layers. Such ceramic multilayer substrates are often modularized by mounting electronic components on the surface, but if the electronic components are not thin, the overall height of the module may increase undesirably. 2. Description of the Related Art Conventionally, a technique for providing a cavity in which a component is placed in a ceramic multilayer substrate in advance is known.

Conventionally, such a cavity has been manufactured by the following procedure. First, among the ceramic green sheets corresponding to each layer of the ceramic multilayer substrate, through holes for cavities are formed in a plurality of green sheets arranged on the upper layer side. At this time, the diameters of the through holes are made different from each other for each layer, and the green sheets having a small diameter are sequentially stacked on the green sheet having no cavity through holes. In other words, the cavity through-hole of the green sheet to be stacked next is larger than the cavity through-hole of the green sheet located in the lower layer, and the diameter of the cavity through-hole of the green sheet stacked in the uppermost layer is the largest. Is set as follows. When the required number of green sheets are stacked in this manner, a stepped wall surface is formed by the peripheral portions of the through holes having different diameters, and this stepped wall surface becomes the inner wall surface of the cavity surrounding the electronic component mounting surface. Therefore, a ceramic multilayer substrate having a cavity in which an electronic component is disposed can be obtained by pressurizing and firing such a laminate of green sheets (see, for example, Patent Document 1).
JP-A-7-193163 (2nd page, FIG. 4)

  By the way, in the case of a ceramic multilayer substrate without a cavity, the routing of the wiring that becomes the conduction path of the electronic component mounted on the surface layer is more than the wiring structure in which the wiring patterns between the surface layer and the interlayer are made conductive by connecting via holes in series. The wiring structure in which the conductive paths are concentrated on the surface layer is easier to manufacture, and productivity and reliability of conduction can be improved. However, in the case of a conventional ceramic multilayer substrate with a cavity, when the conduction paths of electronic components arranged in the cavity are concentrated on the surface layer, the wiring pattern is a stepped shape of a cavity constituted by a plurality of green sheets. Since it must be provided along the inner wall surface, the manufacturing process becomes complicated and the reliability of conduction is also lowered. That is, when the inner wall surface of the cavity is formed in a stepped shape by a plurality of green sheets, there is a problem that it is not easy to provide a desired wiring pattern on the inner wall surface.

  When the electronic component mounted in the cavity of the ceramic multilayer substrate is a light emitting element such as a chip LED, the brightness is increased by providing a reflective film made of a reflective material such as silver on the inner wall surface of the cavity. However, if the shape of the inner wall surface of the cavity is stepped, even if a reflective film is provided on the inner wall surface, more light is reflected in an undesired direction. The problem that it cannot be used arises.

  The present invention has been made in view of the actual situation of the prior art, and a first object of the present invention is to easily provide a desired wiring pattern or reflecting film on the inner wall surface of the cavity in which the electronic component is disposed. It is to provide a ceramic multilayer substrate with a cavity. The second object of the present invention is to provide a method for producing such a ceramic multilayer substrate with a cavity.

  In order to achieve the first object described above, in the present invention, the electronic component is mounted on a ceramic multilayer substrate that is manufactured by pressing and firing a laminate of ceramic green sheets and has a cavity in which the electronic component is disposed. The inner wall surface of the cavity surrounding the surface is curved to be constricted, and the inner wall surface is formed by the uppermost ceramic green sheet.

  If a portion of the uppermost ceramic green sheet is curved in a constricted manner to form the inner wall surface of the cavity, a wiring pattern provided on the inner wall surface can be formed on the uppermost green sheet in advance. Therefore, a wiring pattern with high conduction reliability can be easily provided on the inner wall surface of the cavity. Further, since the inner wall surface of the cavity is not a stepped shape but a curved curved surface, it is easy to provide a desired reflective film on the inner wall surface.

  That is, in order to consolidate the conduction paths of the electronic components arranged in the cavity on the surface layer, when providing a wiring pattern to be a conduction path of the electronic components on the inner wall surface of the cavity, the wiring pattern is previously set in the uppermost layer. Since it suffices to form it on the green sheet, it becomes easy to provide a wiring pattern with high conduction reliability on the inner wall surface of the cavity. Further, when the electronic component disposed in the cavity is a light emitting element, a reflective film made of a reflective material such as silver may be provided on the inner wall surface of the cavity. Since the light emitted from the light emitting element is easily reflected in a desired direction by the reflective film, the reflected light can be effectively used.

In order to achieve the second object, in the present invention,
In the method of manufacturing a ceramic multilayer substrate having a cavity in which an electronic component is disposed, the cavity through-hole is formed on a ceramic green sheet on which the cavity through-hole is not formed, and the perforation is formed for each layer. A laminating step of laminating a plurality of layers of ceramic green sheets having different hole diameters to form an uncompressed laminate, and pressing the uncompressed laminate with an isotropic pressure pressing device to form a multilayer unfired block body By laminating each ceramic green sheet so that the diameter of the through hole gradually becomes smaller on the upper layer side in the laminating step, comprising a crimping step to bend and a firing step to fire the unfired block body, A curved surface in which the peripheral portion of the through hole of the uppermost ceramic green sheet is depressed in the crimping step so that the surface of the peripheral portion is constricted. None were as inner wall surface of the cavity surrounding the mounting surface of the electronic component is formed by 該湾 curved.

  In the step of laminating a plurality of layers of ceramic green sheets having cavity through holes in this way, if the diameters of the cavity through holes of each green sheet are laminated so as to gradually become smaller on the upper layer side, these through holes are continuous. Therefore, when an isotropic pressure (hydrostatic pressure) is applied in the next crimping process, the portion of each green sheet protruding to the recess is folded so as to overlap. Curves and sinks into the recess. As a result, since the peripheral portion of the cavity through hole of the uppermost green sheet covers the peripheral portion of the cavity through hole of the lower layer green sheet, the surface of the peripheral portion of the uppermost green sheet is the inner wall surface of the cavity. Thus, the shape becomes a curved surface with a constriction. Therefore, when it is desired to consolidate the conduction paths of electronic components arranged in the cavity on the surface layer, it is only necessary to form the wiring pattern on the uppermost green sheet in advance, and thus a wiring pattern with high conduction reliability. Can be easily provided on the inner wall surface of the cavity. Further, since the inner wall surface of the cavity is not a stepped shape but a curved curved surface, it is easy to provide a desired reflective film on the inner wall surface.

  Since the ceramic multilayer substrate with cavities of the present invention has a portion of the uppermost ceramic green sheet curved in a constricted manner to form the inner wall surface of the cavity, the electronic component disposed in the cavity on the inner wall surface is formed. A wiring pattern serving as a conduction path can be easily provided, and the conduction reliability of the wiring pattern can be easily ensured. In addition, since the inner wall surface of the cavity is not a stepped shape but a curved curved surface, if the electronic component placed in the cavity is a light emitting element, a desired reflective film is easily provided on the inner wall surface. be able to.

  The method for manufacturing a ceramic multilayer substrate with cavities according to the present invention includes a step of laminating a plurality of layers of ceramic green sheets having cavity through holes, wherein the diameter of the cavity through holes of each green sheet is gradually reduced on the upper layer side. When the isotropic pressure (hydrostatic pressure) is applied in the subsequent crimping process, the peripheral portion of the cavity through hole for the uppermost green sheet is depressed and the surface of the peripheral portion is constricted. The inner wall surface of the cavity is formed by the curved surface. Therefore, when it is desired to consolidate the conduction paths of electronic components arranged in the cavity on the surface layer, it is only necessary to form the wiring pattern on the uppermost green sheet in advance, and thus a wiring pattern with high conduction reliability. Can be easily provided on the inner wall surface of the cavity. Further, since the inner wall surface of the cavity is not a stepped shape but a curved curved surface, it is easy to provide a desired reflective film on the inner wall surface.

  An embodiment of the invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part of a ceramic multilayer substrate according to a first embodiment of the present invention, and FIG. 2 is a manufacturing process diagram of the ceramic multilayer substrate.

  A ceramic multilayer substrate 1 shown in FIG. 1 is obtained by laminating a plurality of (for example, seven layers) green sheets 1a to 1g made of a low-temperature fired ceramic (LTCC) and pressing and firing them. A cavity 2 in which the electronic component 40 is disposed is formed on the surface layer. The inner wall surface 21 of the cavity 2 is a curved curved surface, and the flat inner bottom surface of the cavity 2 surrounded by the inner wall surface 21 is a mounting surface 22 for the electronic component 40. The inner wall surface 21 is a part of the uppermost green sheet 1g, and the mounting surface 22 is a part of the third-layer green sheet 1c. Further, another electronic component 41 is mounted on the flat portion of the uppermost green sheet 1g, and wiring patterns 3 and 4 for conducting the electronic component 41 and the electronic component 40 in the cavity 2 are respectively green sheets 1g and 1c. Is provided on the surface.

  Next, a method for manufacturing the ceramic multilayer substrate 1 shown in FIG. 1 will be described with reference to FIG. First, after forming necessary wiring patterns, via holes, cavity through holes, and the like on the green sheets 1a to 1g, the green sheets 1a to 1g are sequentially stacked as shown in FIG. An uncompressed laminate 5 as shown in b) is formed. However, the through-holes for cavities are not formed in the green sheets 1a to 1c on the lower layer side of the uncompressed laminated body 5, and the through-holes for cavities 2d to 2g having different diameters are formed on the upper green sheets 1d to 1g. Is formed. The cavity through hole 2e of the upper green sheet 1e has a smaller diameter than the cavity through hole 2d of the green sheet 1d, and the cavity through hole 2f of the upper green sheet 1f has a smaller diameter. The cavity through-hole 2g of the upper green sheet 1g has the smallest diameter. That is, in this laminating step, the green sheets 1a to 1c are sequentially laminated, and then the green sheets 1d to 1g are sequentially laminated so that the cavity through holes 2d to 2g are continuous so that the upper layer side gradually becomes smaller in diameter. A recess 6 having a narrowed top is formed by the holes 2d to 2g. As shown in FIG. 2 (b), the recess 6 is formed by laminating the through-hole peripheral portions 10d to 10g of the green sheets 1d to 1g defining the through-holes 2d to 2g for the cavities in a reverse step shape. It is a space created by

  Then, after the uncompressed laminated body 5 is put in a bag (not shown) and vacuum-packed, a pressure-bonding process is performed in which the pressure-bonded laminate 5 is pressurized with an isotropic pressure press (not shown). In this crimping step, an isotropic pressure (hydrostatic pressure) as shown by an arrow in FIG. 2B is applied to the unbonded laminate 5, so that an unfired block having a multilayer structure as shown in FIG. A body 7 is obtained. That is, by this crimping step, the laminated green sheets 1a to 1g are crimped, and the through hole peripheral portions 10e to 10g of the green sheets 1e to 1g protruding to the inside of the recess 6 are folded so as to be folded. Curved into a recess and depressed into the recess 6. As a result, the through hole peripheral portion 10d of the fourth green sheet 1d is covered with the through peripheral portion 10e of the fifth green sheet 1e, and the through peripheral portion 10e of the fifth green sheet 1e is 6th. The through hole peripheral portion 10f of the sixth green sheet 1f is covered with the through peripheral portion 10g of the uppermost green sheet 1g. In this way, since the through hole peripheral portions 10d to 10f of the green sheets 1d to 1f are all covered by the through hole peripheral portion 10g of the uppermost green sheet 1g, the surface of the through peripheral portion 10g of the uppermost green sheet 1g is It becomes the inner wall surface 21 of the cavity 2, and its shape is a curved curved surface.

  Thereafter, the unfired block body 7 shown in FIG. 2 (c) is fired to obtain the ceramic multilayer substrate 1, and the electronic components 40, 41, etc. are mounted on the surface layer of the ceramic multilayer substrate 1 in FIG. The module shown is completed.

  As described above, in the present embodiment, in the step of laminating the plurality of green sheets 1d to 1g having the cavity through holes 2d to 2g, the cavity through holes 2d to 2g of the green sheets 1d to 1g are formed. Since lamination is performed so that the diameter gradually becomes smaller on the upper layer side, when isotropic pressure (hydrostatic pressure) is applied in the subsequent crimping process, the peripheral edge portion 10 g of the through hole of the uppermost green sheet 1 g is depressed and the surface thereof is The curved surface is narrow and the inner wall surface 21 of the cavity 2 is formed by the curved surface. Therefore, the wiring pattern 3 serving as a conduction path for the electronic component 40 disposed in the cavity 2 can be easily provided on the inner wall surface 21 of the cavity 2 by forming it in advance on the uppermost green sheet 1g. It is easy to ensure the conduction reliability of the wiring pattern 3. That is, in the conventional product, since the inner wall surface of the cavity is formed in a stepped shape by a plurality of green sheets, it was not easy to provide a wiring pattern on the inner wall surface. If the wall surface 21 is formed as a curved surface made of the uppermost green sheet 1g, it is easy to provide the wiring pattern 3 on the inner wall surface 21, so that the conduction paths of the electronic components 40 are concentrated on the surface layer of the ceramic multilayer substrate 1. Thus, productivity and conduction reliability can be improved.

  FIG. 3 is a cross-sectional view of an essential part of a ceramic multilayer substrate according to a second embodiment of the present invention, and FIG. 4 is a manufacturing process diagram of the ceramic multilayer substrate. Parts corresponding to those in FIGS. Since they are attached, overlapping description will be omitted as appropriate.

  In the ceramic multilayer substrate 31 shown in FIG. 3, the electronic component disposed in the cavity 2 is a light emitting element 42 made of a chip LED, and thus a reflective film 32 is provided on the inner wall surface 21 of the cavity 2. Further, in the ceramic multilayer substrate 31, the reflective film 32 is provided on almost the entire inner wall surface 21 of the cavity 2 by providing the via holes 33 and 34 and the interlayer wiring pattern 35 as a conduction path between the electronic components 42 and 41. Designed to.

  The manufacturing method of the ceramic multilayer substrate 31 shown in FIG. 3 is basically the same as that of the first embodiment described above. That is, first, a required wiring pattern, a via hole, a cavity through hole, and the like are formed in each of the green sheets 1a to 1g. At this time, as shown in FIG. 4A, a reflective film 32 is formed by printing a reflective material such as silver in a predetermined region including the peripheral edge portion 10g of the uppermost green sheet 1g. And each green sheet 1a-1g is laminated | stacked one by one, and the uncompressed laminated body 5 which has the recess 6 which is narrowed as shown in FIG.4 (b) is formed. In the same manner as in the first embodiment, the recess 6 is formed by continuing the cavity through holes 2d to 2g of the green sheets 1d to 1g so that the upper layer side gradually becomes smaller in diameter. Then, by performing a crimping process of pressing the uncompressed laminate 5 with an isotropic pressure press device (not shown), and applying an isotropic pressure (hydrostatic pressure) as indicated by an arrow in FIG. An unsintered block body 7 having a multilayer structure as shown in FIG. By this crimping process, the laminated green sheets 1a to 1g are crimped and the perforated peripheral edge portions 10e to 10g of the green sheets 1e to 1g protruding to the inside of the recess 6 are folded so as to be folded. Since it curves and sinks into the recess 6, the surface of the peripheral edge portion 10 g of the through hole of the uppermost green sheet 1 g becomes the inner wall surface 21 of the cavity 2, and its shape becomes a curved curved surface. As a result, the inner wall surface 21 of the cavity 2 is widely covered with the reflective film 32. Thereafter, the ceramic multilayer substrate 31 is obtained by firing the unfired block body 7 shown in FIG.

  As described above, in the present embodiment example, since the reflection film 32 is provided on the inner wall surface 21 of the cavity 2, the light emitted from the light emitting element 42 disposed in the cavity 2 is reflected along a narrow curved surface. The film 32 can be effectively reflected in a desired direction. That is, in the conventional product, since the inner wall surface of the cavity is formed in a stepped shape, even if a reflective film is provided on the inner wall surface, the emitted light of the light emitting element disposed in the cavity is undesired in the reflective film. However, if the reflecting film 32 is provided along a curved curved surface as in the present embodiment, the reflected light can be used effectively and the brightness is increased. Further, since the reflective film 32 can be formed in advance on the green sheet 1g, it is easy to provide the reflective film 32 on the inner wall surface 21 of the cavity 2.

It is principal part sectional drawing of the ceramic multilayer substrate which concerns on the example of 1st Embodiment of this invention. It is a manufacturing process figure of the ceramic multilayer substrate shown in FIG. It is principal part sectional drawing of the ceramic multilayer substrate which concerns on the example of 2nd Embodiment of this invention. FIG. 4 is a manufacturing process diagram of the ceramic multilayer substrate shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 Ceramic multilayer substrate 1a-1g Green sheet 2 Cavity 2d-2g Cavity through-hole 3,4 Wiring pattern 5 Uncrimped laminated body 6 Recess 7 Unfired block body 10d-10g Perforation peripheral part 21 Inner wall surface 22 Mounted Surface 32 Reflective film 40, 41 Electronic component 42 Light emitting element

Claims (4)

In a ceramic multilayer substrate that is manufactured by pressing and firing a laminate of ceramic green sheets and has cavities in which electronic components are placed,
An inner wall surface of the cavity surrounding the electronic component mounting surface is curved to be constricted, and the inner wall surface is formed by the uppermost ceramic green sheet. substrate.   2. The ceramic multilayer substrate with a cavity according to claim 1, wherein a wiring pattern serving as a conduction path for the electronic component is provided on the inner wall surface of the cavity.   2. The ceramic multilayer substrate with a cavity according to claim 1, wherein the electronic component is a light emitting element, and a reflection film is provided on the inner wall surface of the cavity. In a method for manufacturing a ceramic multilayer substrate having a cavity in which an electronic component is disposed,
A plurality of ceramic green sheets each having a hole for the cavity and having different apertures for each layer are laminated on the ceramic green sheet having no hole for the cavity. A laminating process for forming a pressure-bonded laminate;
A pressure bonding step of forming an unfired block body having a multilayer structure by pressurizing the unbonded laminate with an isotropic pressure press;
A firing step of firing the unfired block body,
In the laminating step, by laminating the ceramic green sheets so that the diameter of the through hole gradually becomes smaller on the upper layer side, the peripheral portion of the through hole of the uppermost ceramic green sheet is depressed in the crimping step. A cavity-coated ceramic multilayer characterized in that the surface of the peripheral portion is formed as a constricted curved surface, and an inner wall surface of the cavity surrounding the mounting surface of the electronic component is formed by the curved surface. A method for manufacturing a substrate.

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