JP2009160840A - Ceramic substrate and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic substrate restrained in the deformation of ceramic green sheets, and to provide a method for production thereof. <P>SOLUTION: The ceramic substrate 1 consists of a ceramic laminate formed by stacking ceramic green sheets 2 having a predetermined thickness, pressurizing and sitering them. From the surface of the ceramic substrate 1 to the depth D1 the opening dimension of the cavity 5 is set to gradually become larger and from the depth D2 deeper than D1 to the depth D3 the opening dimension of the cavity 5 is set to gradually become smaller. Between the depths D1 and D2 the opening dimension of the cavity is set to become largest. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceramic substrate and a manufacturing method thereof, and more particularly to a multilayer ceramic substrate formed by stacking ceramic green sheets having a predetermined thickness and a manufacturing method thereof.

  The laminated ceramic substrate is formed by pressing the laminated ceramic green sheets under heating to integrate the ceramic green sheets, and then firing and plating. A through hole or a via hole is previously formed in the ceramic green sheet by a die punching or a laser processing machine, and a wiring pattern is formed by a screen printing method or the like.

  As one form of such a ceramic substrate, there is a ceramic substrate in which a cavity for mounting an integrated circuit IC is formed. In this type of ceramic substrate, when pressurization using an upper mold and a lower mold is used, it is necessary to pressurize the ceramic green sheet for each number of cavities. For this reason, the dimensions of the ceramic substrate may vary due to the difference in density between the pressed ceramic green sheet and the newly laminated ceramic green sheet, the warpage of the substrate due to the alteration due to heating, or the like.

In order to reduce such dimensional variations, various methods have been proposed in which a laminate of ceramic green sheets is pressed by various isostatic pressing methods. In this method, the ceramic green sheet laminate is pressed in a state where the ceramic green sheet laminate that has been waterproofed by a vacuum pack or the like is immersed in a high-pressure water tank. In particular, in this isostatic pressing method, it is possible to pressurize the ceramic green sheet regardless of the presence or absence of a cavity. In addition, there exist patent document 1 and patent document 2 as a hydrostatic pressure press system in case there exists a cavity. Patent Document 1 proposes a method of manufacturing a ceramic substrate using an elastic body that follows a cavity. Patent Document 2 proposes a method of reducing the opening size toward the bottom of the cavity.
JP 2002-76623 A JP 2003-224360 A

  However, the conventional ceramic substrate manufacturing method has the following problems. When the ceramic green sheet is covered with an elastic body and pressed by an isostatic pressing method, the elastic body is deformed from the surface of the ceramic green sheet toward the bottom of the cavity. At this time, since the elastic body is largely bent at the upper part (opening end) of the cavity and the bottom part of the cavity, a gap is formed between the ceramic green sheet and the elastic body at the bent part. . Pressure does not act on the ceramic green sheet in which the gap is formed, and after pressurization, a difference occurs in the density of the ceramic green sheet. As a result, the ceramic green sheet may be deformed when the ceramic green sheet is sintered.

  The present invention has been made to solve the above problems, and one object is to provide a ceramic substrate in which deformation of the ceramic green sheet is suppressed, and another object is to provide such a ceramic substrate. It is to provide a manufacturing method.

  The ceramic substrate according to the present invention includes a ceramic laminate and a cavity. In the ceramic laminate, ceramics having a predetermined thickness are laminated. The cavity is formed in the ceramic laminate, and the opening dimension from the outermost surface of the ceramic laminate to the first depth is set to be gradually increased, and the second depth from the second depth deeper than the first depth to the second depth is set. The opening size up to the third depth deeper than the depth is set to be gradually reduced.

  The method for manufacturing a ceramic substrate according to the present invention includes the following steps. A 1st laminated body is formed by laminating | stacking the several ceramic green sheet in which the opening part from which a magnitude | size differs for every ceramic green sheet in the aspect which becomes large gradually. A second laminated body is formed by laminating a plurality of other ceramic green sheets in which openings having different sizes for each ceramic green sheet are formed on the first laminated body in such a manner that the openings gradually become smaller. To do. The surface of the second laminate including the surface of the cavity formed by the first laminate and the second laminate is covered with an elastic body having a predetermined thickness. Pressure is applied to the elastic body. The first laminate and the second laminate are sintered.

  According to the ceramic substrate of the present invention, in the cavity formed in the ceramic laminated body, the opening dimension from the outermost surface of the ceramic laminated body to the first depth is set to be gradually increased. The opening dimension from the deep second depth to the third depth deeper than the second depth is set to be gradually reduced. Thereby, when the ceramic green sheet used as a ceramic laminated body is covered and pressurized with an elastic body, the inner wall of a cavity can be pressurized uniformly and a deformation | transformation of a ceramic substrate can be suppressed.

  According to the method for manufacturing a ceramic substrate according to the present invention, in the first laminated body of ceramic green sheets, the openings are laminated in such a manner that the opening gradually increases, and in the second laminated body formed on the first laminated body, The surface of the second laminated body including the surfaces of the cavities formed by the first laminated body and the second laminated body is laminated on the first laminated body in such a manner that the opening is gradually reduced. The inner wall of the cavity can be uniformly pressurized when covered and pressurized by the elastic body having a thickness. As a result, deformation of the ceramic substrate can be suppressed.

Embodiment 1
A ceramic substrate according to an embodiment of the present invention will be described. As shown in FIGS. 1 and 2, the ceramic substrate 1 having a cavity 5 is made of a ceramic laminate formed by laminating, pressing and sintering a ceramic green sheet 2 having a predetermined thickness. Become. For example, Al ₂ O ₃ is applied as the material of the ceramic green sheet 2. The dimensions of the cavity 5 are, for example, C1 = 5 mm and C2 = 10 mm. The corner of the cavity 5 is rounded (for example, R 0.5 mm) so that the ceramic green sheet portion is not broken when the cavity 5 is formed.

  The thickness of the ceramic green sheet before pressing is, for example, about 0.1 mm. The cavity 5 is formed by laminating, for example, nine layers of ceramic green sheets in which openings having predetermined dimensions are formed. Therefore, the depth of the cavity before pressurization in this case is about 0.9 mm, and the depth becomes slightly shallower after pressurization and sintering treatment. The ceramic substrate is formed by laminating, for example, 14 layers of ceramic green sheets. The thickness of the ceramic substrate before pressurization is about 1.4 mm, and the thickness after pressurization and sintering is performed. Is a little thinner than this.

  In the present ceramic substrate 1, the opening size of the cavity 5 is set so as to gradually increase from the surface of the ceramic substrate 1 to the depth D1. On the other hand, from the depth D2 to the depth D3 which is deeper than the depth D1, the opening size of the cavity 5 is set to be gradually reduced. Between the depth D1 and the depth D2, it sets so that the opening dimension of a cavity may become the largest. As will be described later, the cavity 5 is formed by laminating ceramic green sheets having openings with gradually increasing opening dimensions, and ceramic green sheets having opening portions with gradually decreasing opening dimensions. It is formed by laminating. In the sintered ceramic substrate 1, the boundary of each layer of the ceramic green sheet is lost and cannot be discriminated, but in FIG. 2, the boundary is shown for convenience of explanation.

Embodiment 2
Here, the manufacturing method of the ceramic substrate mentioned above is demonstrated. The ceramic substrate is formed by laminating ceramic green sheets having a predetermined thickness. When laminating ceramic green sheets, a laminating jig is used. As shown in FIG. 3, the stacking jig 11 is provided with positioning pins 12 and guides (not shown) at predetermined positions. The ceramic green sheet has a guide hole through which the positioning pin is inserted. The stacking accuracy of the ceramic green sheets is determined by the processing accuracy of the positioning pins 12. In this case, the entire surface of the ceramic green sheets is about 5 μm.

  As shown in FIG. 4, the first ceramic green sheet 2a is laminated so that the guide hole 3 of the ceramic green sheet 2a is aligned with the position of the positioning pin 12, and the positioning pin 12 is inserted into the guide hole 3. 11 is mounted. Next, as shown in FIG. 5, the second ceramic green sheet 2b is placed on the first ceramic green sheet 2a. Similarly, the third to fifth ceramic green sheets 2c, 2d, and 2e are sequentially laminated on the second ceramic green sheet 2b.

  Next, as a ceramic green sheet, a green sheet in which openings serving as cavities are formed is laminated. As shown in FIG. 6, a sixth-layer ceramic green sheet 2f having an opening 4a is laminated on the fifth-layer ceramic green sheet 2e. On the sixth ceramic green sheet 2f, a seventh ceramic green sheet 2g having an opening 4b and an eighth ceramic green sheet 2h having an opening 4c are sequentially laminated. The

  At this time, as shown in FIG. 7, the dimension of the opening 4b of the ceramic green sheet 2g is set to be 20 μm (one side length L = 10 μm) larger than the dimension of the opening 4a of the ceramic green sheet 2f immediately below, The size of the opening 4c of the ceramic green sheet 2h is set to be 20 μm (one side length L = 10 μm) larger than the size of the opening 4b of the ceramic green sheet 2g immediately below.

  Next, as shown in FIG. 8, a ninth ceramic green sheet 2i having an opening 4d is laminated on the eighth ceramic green sheet 2h. The size of the opening 4d of the ceramic green sheet 2i is set to be 20 μm larger than the size of the opening 4c of the ceramic green sheet 2h immediately below. On the ceramic green sheet 2i, a tenth ceramic green sheet 2j having an opening 4e and an eleventh ceramic green sheet 2k having an opening 4f are sequentially laminated. The dimensions of the openings 4d to 4f are the same.

  Next, as shown in FIG. 9, a 12th ceramic green sheet 2m having an opening 4g is laminated on the 11th ceramic green sheet 2k. A 13th ceramic green sheet 2n having an opening 4h and a 14th ceramic green sheet 2p having an opening 4i are sequentially laminated on the 12th ceramic green sheet 2m. The

  At this time, as shown in FIG. 10, the size of the opening 4g of the ceramic green sheet 2m is set to be 20 μm (one side length L = 10 μm) smaller than the size of the opening 4f of the ceramic green sheet 2k immediately below, The size of the opening 4h of the ceramic green sheet 2n is set to be 20 μm (one side length L = 10 μm) smaller than the size of the opening 4g of the ceramic green sheet 2m immediately below. The dimension of the opening 4i of the ceramic green sheet 2p is set to be 20 μm (one side length L = 10 μm) smaller than the dimension of the opening 4h of the ceramic green sheet 2n immediately below.

  Next, as shown in FIG. 11, a metal plate 13 for suppressing deformation of the ceramic green sheet 2p is disposed on the uppermost ceramic green sheet 2p. The metal plate 13 is formed with openings 13a having the same size as the openings 4d to 4f formed in the ceramic green sheets 2i to 2k. The cavity 5 is formed by laminating the ceramic green sheets 2f to 2p in which the openings 4a to 4i are formed.

  Next, as shown in FIG. 12, silicon rubber 14 having a thickness of about 1 mm is formed as an elastic body so as to cover the inner wall surface of the cavity 5 and the metal plate 13 formed in the laminated ceramic green sheets 2a to 2p. Laminated. Next, as shown in FIG. 13, the laminated ceramic green sheets 2a to 2p and the like are put in a predetermined vacuum bag 15 together with the lamination jig 11, and as shown in FIG. The air is extracted by a vacuum pump (not shown) to be in a vacuum packed state.

  Next, an isostatic pressing process is performed on the ceramic green sheets 2a to 2p and the like in a vacuum packed state. The conditions of the hydrostatic press treatment are, for example, a temperature of about 20 ° C., a pressure of about 35 MPa to 50 MPa, and a water temperature of 90 ° C. The water temperature is determined by the softening temperature of the binder material in the ceramic green sheet, and the pressure is determined by the density and shrinkage after the ceramic green sheet is sintered.

  After the isostatic pressing, the stacking jig 11 is taken out from the vacuum bag. Next, the metal plate 13 is removed from the lamination jig 11, and the laminated ceramic green sheets are removed. Next, the ceramic green sheet taken out is subjected to a sintering process. An example of the sintering process is shown in FIG. As shown in FIG. 15, the ceramic green sheet is first heated from room temperature to a predetermined temperature (first temperature) over several hours, and is held for several hours under the first temperature. Next, the temperature is raised to a predetermined temperature (second temperature) higher than the first temperature over several minutes to several hours, and the temperature is held for several minutes to several hours under the second temperature. Thereafter, the temperature is lowered to room temperature over several hours to several tens of hours. Thus, as shown in FIG. 16, the ceramic substrate 1 having the cavity 5 is manufactured.

  The ceramic substrate described above is formed by laminating ceramic green sheets in which openings having gradually different opening dimensions are formed, so that the inner wall of the cavity of the ceramic green sheet is almost the same when the hydrostatic pressing process is performed. Uniform pressure can be applied. This will be described using a ceramic substrate according to a comparative example as an example.

  As shown in FIG. 17, in the ceramic substrate 101 according to the comparative example, first, predetermined green sheets including a ceramic green sheet in which an opening serving as a cavity is formed are sequentially stacked on the stacking jig 111. A metal plate is placed on the uppermost ceramic green sheet 102, and an elastic body 114 such as silicon rubber is placed so as to cover the inner wall of the cavity and the metal plate.

  In the ceramic substrate according to the comparative example, the ceramic green sheet 102 in which openings having the same dimensions as the openings serving as cavities are used as the ceramic green sheets. Therefore, the elastic body 104 is deformed from the surface of the ceramic green sheet 102 toward the bottom of the cavity 105. At this time, in particular, the elastic body 104 is largely bent at the top (opening end) and the bottom of the cavity 105.

  In the portion where the elastic body 104 is bent, a gap 116 is formed between the elastic body 104 and the ceramic green sheet 102, and the pressure does not uniformly act on the ceramic green sheet 102 when the isostatic pressing is performed. The sheet 102 has a relatively high density portion and a low density portion. That is, the density is relatively low at the top (opening end) and bottom of the cavity 105 where the gap 116 is formed. Therefore, as shown in FIG. 18, when the sintering process is performed, the ceramic green sheet 102 is deformed at the upper part (inside the dotted line round frame A) and the bottom part (in the dotted line round frame B) of the cavity 105.

  On the other hand, in the ceramic substrate 1 described above, when the hydrostatic pressure treatment is performed, the ceramic green sheets 2 each having the opening 4 whose dimensions are adjusted so that the elastic body 14 follows the surface of the cavity 5 are laminated. It is formed by doing. Therefore, the formation of a gap between the elastic body 4 and the ceramic green sheet 2 is suppressed, and the pressure acts on the ceramic green sheet 2 almost uniformly when the hydrostatic pressure pressing process is performed. Variation is reduced. As a result, deformation of the ceramic green sheet 2 can be suppressed.

  Actually, in the bottom part of the cavity, the region where the ceramic green sheet is deformed is evaluated, and as shown in FIG. 19, this is from the end of the region P where the hydrostatic pressure acts uniformly to the side wall of the cavity. The distance S was obtained. As a result, it was confirmed that in the ceramic substrate according to the comparative example, the distance S was about 0.6 mm, whereas in this ceramic substrate, the distance S was reduced to about 0.1 mm. This is considered to indicate that in the present ceramic substrate, the pressurizing region on the wall surface and the bottom surface of the bottom of the cavity is expanded along the step of the ceramic green sheet.

  Further, in the ceramic substrate according to the comparative example, deformation of the ceramic green sheet due to the misalignment of the ceramic green sheets was recognized in the upper part of the cavity, and generation of foreign matters was confirmed. On the other hand, in the present ceramic substrate, the difference in the opening size of the cavity in the ceramic green sheet is set to be equal to or larger than the maximum deviation amount when the ceramic green sheets are laminated. Accordingly, it was confirmed that the influence of the positional deviation of the opening serving as the cavity on the deviation at the time of stacking the ceramic green sheets is relatively small, and the deformation of the ceramic green sheet at the upper part of the cavity is extremely small.

  These results show that in the region from the top to the bottom of the cavity, the elastic body is deformed so as to follow the step of the ceramic green sheet even when the gap is generated by the conventional method and can not be pressurized. This is considered to indicate that pressurization is possible.

  In addition, the difference between the size of the opening serving as a cavity in one ceramic green sheet and the size of the opening of another ceramic green sheet laminated thereon is the size of the cavity, the material of the elastic body, and the size of the elastic body. The thickness varies depending on the thickness, the number of ceramic green sheets forming the cavity, the applied pressure, the pressing time, the lamination accuracy, and the like.

  For example, when the hydrostatic pressure treatment is performed using an elastic body having a thickness of 1 mm, when the ceramic green sheets are laminated using laminated pins, the amount of lamination deviation of each ceramic green sheet is about 5 μm. Therefore, as shown in FIG. 20, the dimensional difference L between the openings in each ceramic green sheet is required to be about 10 μm or more. On the other hand, if the dimensional difference L of the opening exceeds about 30 μm, the ceramic green sheet may break. Therefore, the size difference L of the opening in each ceramic green sheet is preferably about 10 μm to 30 μm.

  Further, as shown in FIG. 21, the dimensional difference L1 of the opening on the bottom side of the cavity and the dimensional difference L2 of the opening on the opening side of the cavity may be changed. In particular, when the dimensional difference L1 is set larger than the dimensional difference L2, the dimensional difference L1 may be set to 30 μm or more.

  In the above-described method for manufacturing a ceramic substrate, the planar shape of the cavity of the ceramic substrate has been described by taking, as an example, a substantially rectangular shape with curved corners. As the plane of the cavity, as shown in FIG. 22, even if the cavity 5 is a combination of a straight line and a curve, the elastic body is deformed so as to follow the step of the ceramic green sheet 2, so that the ceramic green sheet 2 deformation can be suppressed.

  In the above-described ceramic substrate manufacturing method, the case where the metal plate is disposed on the uppermost ceramic green sheet has been described as an example. Since the main purpose of the metal plate is to maintain the flatness of the ceramic green sheet, it is not always necessary to dispose the metal plate. Therefore, as shown in FIG. 23, when the metal plate is not provided, the portion 6 around the opening of the cavity 5 is deformed so as to be inclined toward the cavity 5.

Furthermore, the description has been made by taking Al ₂ O ₃ as an example of the material of the ceramic green sheet. The material of the ceramic green sheet may be a general ceramic manufactured by a green sheet lamination method, for example, a material such as TiO ₂ or MgO, or a mixed material system obtained by mixing these materials. Even when these ceramic green sheet materials are used, uniform pressure can be applied and deformation of the ceramic green sheet can be suppressed. It is also possible to apply glass ceramic as a low-temperature sintered material.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the scope described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a top view which shows the ceramic substrate which concerns on Embodiment 1 of this invention. FIG. 2 is a partial cross-sectional view taken along a cross-sectional line II-II shown in FIG. 1 in the embodiment. It is sectional drawing which shows 1 process of the manufacturing method of the ceramic substrate which concerns on Embodiment 2 of this invention. FIG. 4 is a cross-sectional view showing a step performed after the step shown in FIG. 3 in the same embodiment. FIG. 5 is a cross-sectional view showing a step performed after the step shown in FIG. 4 in the same embodiment. FIG. 6 is a cross-sectional view showing a step performed after the step shown in FIG. 5 in the same embodiment. FIG. 7 is a partial enlarged cross-sectional view in the step shown in FIG. 6 in the same embodiment. FIG. 7 is a cross-sectional view showing a step performed after the step shown in FIG. 6 in the same embodiment. FIG. 9 is a cross-sectional view showing a step performed after the step shown in FIG. 8 in the same embodiment. FIG. 10 is a partially enlarged cross-sectional view in the step shown in FIG. 9 in the same embodiment. FIG. 10 is a cross-sectional view showing a step performed after the step shown in FIG. 9 in the same embodiment. FIG. 12 is a cross-sectional view showing a step performed after the step shown in FIG. 11 in the same embodiment. FIG. 13 is a cross-sectional view showing a step performed after the step shown in FIG. 12 in the same embodiment. FIG. 14 is a cross-sectional view showing a step performed after the step shown in FIG. 13 in the same embodiment. FIG. 15 is a diagram showing a processing process of a step performed after the step shown in FIG. 14 in the same embodiment. FIG. 16 is a cross-sectional view showing a step performed after the step shown in FIG. 15 in the same embodiment. It is sectional drawing for demonstrating the manufacturing method of the ceramic substrate which concerns on a comparative example. It is sectional drawing for demonstrating the problem of the ceramic substrate which concerns on a comparative example. In the same embodiment, it is a fragmentary sectional view for explaining the operational effect. In the same embodiment, it is the 1st partial sectional view for explaining the size difference of the opening formed in a ceramic green sheet. In the same embodiment, it is the 2nd partial sectional view for explaining the size difference of the opening formed in a ceramic green sheet. In the same embodiment, it is a figure showing the plane shape of the cavity of the ceramic substrate concerning a modification. In the same embodiment, it is a figure showing the section structure of the cavity of the ceramic substrate concerning other modifications.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Ceramic substrate, 2, 2a-2p Ceramic green sheet, 3 Guide hole, 4, 4a-4i opening part, 5 cavity, 6 Cavity opening edge periphery part, 11 Lamination jig, 12 Positioning pin, 13 Metal plate, 14 Elasticity Body, 15 vacuum bag, 16 gap.

Claims (6)

A ceramic laminate in which ceramics of a predetermined thickness are laminated;
An opening dimension formed from the outermost surface of the ceramic laminate to the first depth is set so as to gradually increase, and the second depth that is deeper than the first depth is set to the first depth. And a cavity set so that an opening size to a third depth deeper than a depth of 2 is gradually reduced.   2. The ceramic substrate according to claim 1, comprising a portion where an opening dimension of the cavity is set to be the largest between the first depth and the second depth.   3. The ceramic substrate according to claim 2, wherein the portion having the largest opening dimension of the cavity includes a portion in which at least two layers of the ceramic having a predetermined thickness are laminated. Forming a first laminate by laminating a plurality of ceramic green sheets each having an opening having a different size for each ceramic green sheet in a manner in which the opening gradually increases;
A plurality of other ceramic green sheets in which openings having different sizes are formed for each ceramic green sheet are laminated on the first laminate in such a manner that the openings are gradually reduced. Forming, and
Covering the surface of the second laminate including the surface of the cavity formed by the first laminate and the second laminate with an elastic body having a predetermined thickness;
A method for manufacturing a ceramic substrate, comprising: applying pressure to the elastic body; and sintering the first laminated body and the second laminated body.   Between the step of forming the first laminate and the step of forming the second laminate, at least two ceramic green sheets each having an opening having the largest size are laminated to form an intermediate layer. The manufacturing method of the ceramic substrate of Claim 4 provided with the process of forming.   In the step of forming the first laminate and the step of forming the second laminate, the difference in the size of the opening is set to be larger than the maximum deviation amount when the ceramic green sheets are laminated, The method for manufacturing a ceramic substrate according to claim 4 or 5.

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