JP2010229000A - Production method of ceramic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of a ceramic substrate, capable of reducing a use amount of structural materials of a constraint layer while suppressing or preventing warpage or deformation of a ceramic molded product (ceramic substrate) in a firing process and capable of efficiently producing a ceramic substrate having good characteristics and no warpage or deformation. <P>SOLUTION: The production method of a ceramic substrate includes: a step of forming a green composite laminate 10 in a square form in a plan view, which comprises a sheet laminate 22 for a substrate and a constraint layer 1A disposed on at least either the one principal face side and the other principal face side of the laminate; and a step of firing the green composite laminate at a temperature where a sintering-resistant ceramic powder that constitutes the constraint layer 1A does not sinter. In the method, a green sheet 1 for a constraint layer is used for constituting the constraint layer 1A, the sheet 1 having a larger thickness in regions 2a close to opposing two sides than in other regions 2b, so as to prepare the green composite laminate 10 including the constraint layer 1A having a larger thickness at four corners in a plan view than in a center part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a ceramic substrate, and in particular, is manufactured through a so-called constrained firing process in which a constraining layer is disposed on a ceramic molded body that becomes a ceramic substrate after firing and firing is performed while suppressing shrinkage. The present invention relates to a method for manufacturing a ceramic substrate.

  Among ceramic electronic components, in a multilayer ceramic substrate or the like that requires high planar dimensional accuracy, firing shrinkage in the planar direction in the firing process, variations in the shrinkage, and the like greatly affect product quality.

  Therefore, as a method of firing the ceramic molded body while suppressing shrinkage in such a firing step, for example, as shown in FIG. 16, at the firing temperature of the ceramic molded body 51 on both main surfaces of the ceramic molded body 51. By firing in a state where the constraining layers 52a and 52b, which are made of a hardly sinterable material such as alumina, which does not substantially sinter, are formed as a main component, firing shrinkage in the plane direction is substantially prevented. There has been proposed a firing method that enables firing (see Patent Document 1).

  However, in the case of this method, the binding force by the constraining layer may be insufficient in the peripheral portion of the ceramic molded body, particularly in the vicinity of the corner portion, and the peripheral edge portion of the ceramic molded body such as a ceramic substrate obtained after firing is warped. Deformation may occur.

Therefore, as shown in FIG. 17, at least one of constraining layers (constraint layer green sheets) 62a and 62b disposed on both main surfaces of a ceramic molded body (laminated body) 61 formed by laminating ceramic green sheets. On the other hand (in this example, the constraining layer 62a disposed on the upper surface side of the laminate 61), the constraining layer 62a having the peripheral edge portion A thicker than the thickness of the central portion B is disposed and fired. A method for manufacturing a ceramic substrate has been proposed (see Reference 2).
In the case of this method, since the constraining layer in which the thickness of the peripheral edge portion A is thicker than the thickness of the central portion B is used, the peripheral edge portion of the laminate is reliably restrained with a restraining force larger than that of the central portion. It is possible to prevent warpage and deformation of the peripheral edge.

However, in the case of the method of Patent Document 2, normally, as described in paragraph 0058, the constraining layer green sheet is punched to punch out the central region, and the frame-shaped constraining layer green sheet (frame A constraining layer in which the thickness of the peripheral portion A is made larger than the thickness of the central portion B by, for example, laminating the frame-like sheet on another constraining layer green sheet having a uniform thickness. Since it is necessary to manufacture, there is a problem in that the production efficiency is reduced due to an increase in man-hours.
Moreover, since the punched portion generated in the punching process is discarded as it is, there is a problem that it is not desirable from the viewpoint of resource saving and environmental protection.

JP-A-4-243978 JP 2004-146701 A

  The present invention solves the above-described problems, and can suppress and prevent warping and deformation of a ceramic molded body (ceramic substrate) in a firing process, and can reduce the amount of constituent materials used in the constraining layer. Another object of the present invention is to provide a method for manufacturing a ceramic substrate, which can efficiently manufacture a ceramic substrate having good characteristics without deformation.

  In order to solve the above problems, the inventor has made various studies on causes and mechanisms of warping and deformation of a ceramic substrate formed by firing a laminate of ceramic green sheets, for example, In the case of a square ceramic substrate, it was found that the binding force at the peripheral edge, particularly at the four corners, is likely to be insufficient, and warpage and deformation are likely to occur.

  The reason why the restraining force tends to be insufficient at the four corners is considered to be that the four corners of the peripheral portion are surrounded by only 90 °, and these four corners are more than the other regions of the peripheral portion. It was speculated that the occurrence of warping and deformation could be suppressed by strongly restraining, and the present invention was completed through further experiments and studies.

That is, the method for producing a ceramic substrate of the present invention includes:
The main component is a non-sinterable ceramic powder that does not sinter at least at one of the principal surface side and the other principal surface side of the unfired ceramic molded body that becomes the ceramic substrate after firing at the sintering temperature of the unfired ceramic molded body. A step of forming an unfired composite laminate having a rectangular planar shape in which a constraining layer is disposed;
Firing the unfired composite laminate at a temperature at which the ceramic compact is sintered but the hardly sinterable ceramic powder constituting the constraining layer is not sintered;
A step of removing the constraining layer after the step of firing the unfired composite laminate is completed,
The constraining layer green sheet constituting the constraining layer is a constraining layer green sheet in which the thickness of one side region or the two side regions facing each other is made thicker than the other region. The unfired composite laminate including the constraining layer having a thicker corner than the center portion is formed.

  In the method for producing a ceramic substrate according to the present invention, the unfired ceramic molded body is a laminate formed by laminating a plurality of ceramic green sheets that become ceramic layers after firing, and the unfired composite laminate is fired. The ceramic substrate manufactured through the process is a multilayer ceramic substrate.

  Moreover, it is desirable that the constraining layer is disposed on both the one main surface side and the other main surface side of the ceramic molded body.

  In the method for producing a multilayer ceramic substrate of the present invention, a constraining layer green sheet that constitutes the constraining layer on the one main surface side and a constraining layer green sheet that constitutes the constraining layer on the other main surface side include: When the positional relationship between the one-side region or the two-side regions facing each other is viewed, it is desirable that they are arranged in such a manner that they are plane-symmetric.

  In the method for producing a multilayer ceramic substrate of the present invention, it is desirable to use a constraining layer green sheet that is integrally formed as a whole when forming the sheet, as the constraining layer green sheet.

  The method for producing a ceramic substrate of the present invention is a constraining layer green sheet in which a constraining layer green sheet constituting a constraining layer is formed such that one side region or two opposing side regions are thicker than other regions. Is used to form an unfired composite laminate having a constrained layer with four corners thicker than the central portion when viewed in plan, and is a ceramic to be fired, which becomes a ceramic substrate after firing. It is possible to suppress warpage and deformation at the four corners of the molded body.

In other words, a constraining layer green sheet in which the thickness of one side region or the two side regions facing each other is made thicker than the other region is rotated in a plane as necessary. The thickness of the four corners in the plan view can be obtained by arranging a predetermined number on one or the other main surface of the ceramic molded body without rotating or rotating 90 ° or 180 ° in a plane. It becomes possible to form an unfired composite laminate having a thicker constraining layer, sufficiently restraining the four corners of the ceramic molded body in the firing process, and causing warping and deformation at the four corners of the ceramic molded body Can be suppressed.
In addition, the arrangement | positioning aspect of the green sheet for constrained layers is demonstrated in detail in the below-mentioned Example.

  In the present invention, as described above, a constraining layer green sheet in which the thickness of one side region or the two side regions facing each other is thicker than the other region is used as the constraining layer green sheet. The green sheet for the constraining layer in which the thickness of the one side region or the two side regions facing each other is thicker than the other region is used as a constraining layer as a blade when the sheet is formed by, for example, the doctor blade method. By using a blade having a concave portion and a convex portion corresponding to a thick portion and a thin portion of the green sheet, the green sheet can be produced without requiring a special process.

  Therefore, after forming the frame-shaped constraining layer green sheet by punching the constraining layer green sheet separately, as in the case of manufacturing the constraining layer green sheet having a thick peripheral portion in the above-described conventional technology. This eliminates the need to stack this on another constraining green sheet with a uniform thickness, thereby improving productivity and preventing the occurrence of punched parts to be discarded, thus saving resources. It becomes possible to plan.

  Further, by applying the method for manufacturing a ceramic substrate of the present invention to a method for manufacturing a multilayer ceramic substrate, it becomes possible to efficiently manufacture a highly reliable multilayer ceramic substrate free from warping or deformation.

  In the present invention, a constraining layer is disposed only on one main surface side of the ceramic molded body (for example, a constraining layer having a sufficient thickness as a whole and having four corners thicker than other regions). Although it may be possible to obtain the basic effects of the present invention, it is possible to arrange the constraining layer on both the one main surface side and the other main surface side of the ceramic molded body. It becomes possible to more reliably manufacture a ceramic substrate with less warping and deformation at the four corners, and the present invention can be made more effective.

  Further, in the method for producing a ceramic substrate of the present invention, one side of the constraining layer green sheet constituting the constraining layer on one main surface side and the constraining layer green sheet constituting the constraining layer on the other main surface side When looking at the positional relationship between the side regions or the two side regions facing each other, by arranging them to be plane-symmetric, the balance of how to apply restraining force is improved, and warping and deformation of the ceramic molded body can be further improved. This is desirable because it can be reliably suppressed and prevented.

  In addition, by using a constraining layer green sheet that is formed integrally as a constraining layer green sheet, the constraining layer green sheet is punched, for example, as in the case of the prior art. After forming the frame-like sheet, it becomes unnecessary to laminate this frame-like sheet on a green sheet for a constraining layer having another uniform thickness, and the production efficiency can be kept high, and punching is performed. It is possible to prevent waste of resources due to discarding the portion and increase in environmental load.

It is a figure which shows the green sheet for constrained layers used for manufacturing a multilayer ceramic substrate in the Example (Example 1) of this invention, (a) is a top view, (b) is front sectional drawing. It is a figure which shows the green sheet for constrained layers used for manufacturing the multilayer ceramic substrate for a comparison in Example 1 of this invention, (a) is a top view, (b) is front sectional drawing. It is sectional drawing which shows the structure of the unbaking composite laminated body produced in Example 1 of this invention. It is a disassembled perspective view which shows typically the structure of the unbaking composite laminated body of FIG. 3 produced in Example 1 of this invention. It is a disassembled perspective view which shows typically the structure of the other unbaking composite laminated body produced in Example 1 of this invention. It is a disassembled perspective view which shows typically the structure of the other unbaking composite laminated body produced in Example 1 of this invention. It is a disassembled perspective view which shows typically the structure of the other unbaking composite laminated body produced in Example 1 of this invention. It is a disassembled perspective view which shows typically the structure of the unbaking composite laminated body for a comparison produced in Example 1 of this invention. It is a figure which shows the green sheet for constrained layers used for manufacturing a multilayer ceramic substrate in the other Example (Example 2) of this invention, (a) is a top view, (b) is front sectional drawing. . It is a disassembled perspective view which shows typically the structure of the unbaking composite laminated body produced in Example 2 of this invention. It is a disassembled perspective view which shows typically the structure of the other unbaking composite laminated body produced in Example 2 of this invention. It is a disassembled perspective view which shows typically the structure of the unbaking composite laminated body for comparison produced in Example 2 of this invention. It is a disassembled perspective view which shows typically the structure of the unbaking composite laminated body for comparison produced in Example 2 of this invention. It is a perspective view which shows typically an example of the method of forming the green sheet for constrained layers in enforcing the manufacturing method of the ceramic substrate of this invention. FIG. 6 is a front view schematically showing another example of a method for forming a constraining layer green sheet in carrying out the method for producing a ceramic substrate of the present invention. It is a figure which shows the conventional method of baking a ceramic molded object (constrained baking) using the constrained layer which makes a hardly sinterable material the main component. It is a figure which shows the other method of restraint baking of the ceramic molded object using the conventional constrained layer which makes a hardly sinterable material the main component.

  Hereinafter, the present invention will be described in more detail with reference to embodiments of the present invention.

[Production of green sheet for substrates]
A glass powder obtained by mixing each powder of SiO ₂ , CaO, Al ₂ O ₃ and B ₂ O ₃ was mixed with an alumina powder.

  To this mixed powder, an acrylic organic binder and toluene and ethanol as a solvent are added, mixed, and thoroughly mixed by a ball mill, and then uniformly dispersed, and then defoamed under reduced pressure. To obtain a slurry.

  This slurry was formed into a sheet on a carrier film by a casting method using a doctor blade to produce a glass ceramic green sheet having a thickness of 0.20 mm.

  And after drying this glass ceramic green sheet, it cut | disconnected the whole carrier film so that a plane dimension might be a magnitude | size of 150 mm (square).

  Then, an Ag conductor paste is formed on the cut green sheet (glass ceramic green sheet) by a screen printing method to constitute a ceramic layer of the multilayer ceramic substrate having the conductor pattern 21 (see FIG. 3). A substrate green sheet 20 (see FIG. 3) was produced.

[Preparation of green sheet for constraining layer]
To the alumina powder, polyvinyl butyral as an organic binder and toluene and ethanol as solvents are mixed, mixed thoroughly by a ball mill, and dispersed uniformly, and then subjected to defoaming treatment under reduced pressure to obtain a slurry. Got.

  By forming this slurry into a sheet on a carrier film by a casting method using a doctor blade, the thickness of the two side areas facing each other along the molding direction is 0.20 mm, A green sheet having a thickness of 0.10 mm in the central region sandwiched between the regions was obtained.

And after drying this green sheet, it cuts with the carrier film so that a plane dimension may become a magnitude | size of 150 mm (square), and as shown in FIG. 1, the thickness of the opposing 2 side area | region 2a is 0.20 mm. A constraining layer green sheet 1 in which the thickness of the central region 2b sandwiched between the two two-side regions 2a was 0.10 mm was produced.
In this example, for the constraining layer green sheet 1 having a planar dimension of 150 mm □, the planar dimension (width) of the central region 2b is 95 mm when viewed from the molding direction, and the planar dimension of the opposing two-side region 2a. Each (width) was made to be 27.5 mm.

Further, as shown in FIG. 2, a constraining layer green sheet 52 having a planar dimension of 150 mm □ and a thickness of the entire region in the plane of 0.10 mm was produced.
1 and 2 show the constraining layer green sheets 1 and 52 with the carrier film removed.

  In addition, for example, by the doctor blade method, the thickness of the two side regions facing each other along the molding direction is thick (thickness: 0.20 mm), and the thickness of the central region sandwiched between the two side regions is thin (thickness). : 0.10 mm) When producing a green sheet for a constrained layer, for example, as shown in FIG. 14, a doctor blade having a lower end side blade portion having two concave portions 31 on both sides and one convex portion 32 in the center. A pair of two sides along the molding direction is used by moving the carrier film 33 in the direction of arrow A (molding direction) using the equipment provided with the blade 30 (however, the doctor blade 30 can also be moved). By forming the constraining layer green sheet 1 in which the thickness of the region 2a is large and the thickness of the central region 2b is thin, the entire structure is efficiently formed integrally without going through a plurality of steps. It is possible to obtain a layer green sheet 1.

  Further, as shown in FIG. 15, a doctor blade 30 having a plurality of concave portions 31 and a plurality of convex portions 32 is used to form a sheet having concave portions and convex portions along the forming direction. Is cut along a cut line L, and further cut at a predetermined position perpendicular to the forming direction, whereby a plurality of constraining layer green sheets can be efficiently produced.

  In any case, in the present invention, there is no particular restriction on the method for producing the constraining layer green sheet, and the constraining layer green sheet can be formed using other methods. A method of adjusting the direction, a flat sheet is first produced, and then a second sheet molding is performed on both sides to form a green sheet for a constraining layer having a thick thickness on both sides, a strip-shaped sheet It is also possible to apply a method of laminating on both sides of a flat sheet, a method of printing a ceramic paste only on both sides of a flat sheet by screen printing, and the like.

[Production of multilayer ceramic substrate]
Using the substrate green sheet 20 and the constraining layer green sheet 1 produced as described above, an unfired composite laminate 10 as shown in FIGS. 3 and 4 was produced in the following procedure.

  In producing the unfired composite laminate 10, first, six layers of green sheets for substrates (glass ceramic green sheets) 20 provided with the conductor pattern formed as described above are laminated in a predetermined order. A body (sheet laminate for substrate) 22 was produced. In addition, each green sheet 20 for substrates was peeled off from the carrier film and laminated sequentially.

  Then, the constraining layer green sheet 1 (FIG. 1) peeled off from the carrier film is laminated on both principal surface sides of the substrate sheet laminate 22 and pressed in the laminating direction, whereby the planar dimension is as large as 150 mm □. An unfired laminate before cutting was prepared.

  Next, the unfired laminate before cutting is cut parallel to each edge at a position of 52.5 mm from the center, the planar shape is square, and the length of one side is 105 mm (that is, 105 mm □) green composite laminate 10 (FIGS. 3 and 4) was produced. As a result, the constraining layer green sheet 1 has a planar dimension (width) of the central region 2b of 95 mm and a planar dimension (width) of the opposing two-side region 2a of 5 mm.

  As shown in FIGS. 3 and 4, the unfired composite laminate 10 is a laminate (substrate sheet laminate) formed by laminating a plurality of ceramic green sheets (substrate green sheets) 20 having conductor patterns 21. ) 22 has a structure in which the constraining layer green sheets 1 are disposed on one main surface side and the other main surface side. Further, in this unfired composite laminate 10, as shown in FIGS. 3 and 4, the constraining layer green sheet 1 constituting the constraining layer 1A on one main surface side and the constraining layer 1A on the other main surface side are provided. The constraining layer green sheet 1 is arranged in such a manner that it is plane-symmetric when viewed from the positional relationship of the thick two-side region 2a.

  Then, this unfired composite laminate 10 was fired at a temperature at which the substrate sheet laminate 22 was sintered but the constraining layer green sheet 1 was not sintered, in this example, 800-1050 ° C.

  And the multilayer ceramic substrate of the sample number 1 was obtained by removing the constrained layer which remained on the both main surfaces from the composite laminated body after sintering.

Further, using the constraining layer green sheet 1 shown in FIG. 1, the following unfired composite laminates (1), (2), and (3) were produced.
(1) As shown in FIG. 5, the constraining layer green sheet 1 constituting the constraining layer 1A on the one main surface side of the laminate (substrate sheet laminate) 22 and the constraining layer 1A on the other main surface side are configured. The constraining layer green sheet 1 is an unfired composite laminate 10 disposed in a form rotated by 90 ° when the positional relationship between the thick two-side regions 2a is viewed, and the sample number 2 It becomes a multilayer ceramic substrate.

  (2) As shown in FIG. 6, the constraining layer green sheets 1 are arranged in two planes on both sides of one main surface side and the other main surface side of a laminate (substrate sheet laminate) 22 so as to be symmetrical. An unfired composite laminate 10 that is to be a multilayer ceramic substrate of sample number 3.

  (3) As shown in FIG. 7, two layers of constraining layer green sheets 1 are disposed on both sides of one main surface side and the other main surface side of the laminate (substrate sheet laminate) 22. The two layers of constraining layer green sheets 1 on the main surface side (upper surface side) and the other main surface side (lower surface side) are each arranged in a state rotated by 90 °, and the constraining layer green sheets 1 on the upper surface side and the lower surface side are arranged. Is a non-fired composite laminate 10 in which the constraining layer green sheet 1 is arranged in plane symmetry on the upper surface side and the lower surface side, and is a multilayer ceramic sample No. 4 What becomes a substrate.

  For comparison, the above-described embodiment is used by using a constraining layer green sheet 52 (see FIG. 2) having a planar dimension of 150 mm □ and a thickness of the entire region in the plane of 0.10 mm shown in FIG. As shown in FIG. 8, the constraining layer green sheets 52 are disposed one layer at a time on one main surface side and the other main surface side of the laminate (substrate sheet laminate) 22 in the same manner as in FIG. An unfired composite laminate 10 having a structure, which was cut into 105 mm □ after lamination and before firing, was prepared as a multilayer ceramic substrate of Sample No. 5 as a comparative example.

  And similarly about these unbaked composite laminated bodies 10 shown in FIGS. 5-8, the sheet | seat laminated body 22 for board | substrates is sintered similarly, but the green sheet 1 or 52 for constrained layers is not sintered, ie, Baked at 800-1050 ° C.

  And the multilayer ceramic substrate of the sample numbers 2-5 was obtained by removing the constrained layer which remained on the both main surfaces from the composite laminated body after sintering.

[Characteristic evaluation]
The warpage amount of the produced multilayer ceramic substrate (samples of sample numbers 1 to 5) was examined and evaluated by the following method.
First, the thickness of the central part of the multilayer ceramic substrate was measured with calipers or the like.
Then, a glass plate of 200 mm □ size and a glass plate of 200 mm × 40 mm size were prepared, a metal plate having a known thickness was sandwiched between the two glass plates, and fixed with a crocodile clip to produce a gap gauge. Then, each sample (multilayer ceramic substrate) was passed through the gap gauge, and whether or not it completely passed was examined to evaluate the warpage. For example, when a 0.500 mm thick multilayer substrate passes through a 0.700 mm gap and does not pass through a 0.690 mm gap, the warpage is considered to be 0.190 mm to 0.200 mm. The warp amount was 0.200 mm on the larger side.

  In Table 1, the measurement result and evaluation result of the curvature amount of the multilayer ceramic substrate of the sample of the sample numbers 1-5 obtained by baking each unbaking composite laminated body are shown.

  As shown in Table 1, in the case of the sample of the comparative example of sample number 5, the value of the warp amount was as large as 3.00 mm, whereas in the sample according to the example of the present invention of sample numbers 1 to 4, Both were confirmed to be less than 0.5 mm.

  In the case of sample numbers 1 to 4, this is a stage of an unfired composite laminate in which constraining layers (constraint layer green sheets) are arranged on both main surfaces of the substrate sheet laminate. When the layer is viewed, the requirement of the present invention is satisfied that the thickness of at least four corners includes a thicker layer than the central portion, and the four corners of the substrate sheet laminate are reliably restrained. It is considered that warpage and deformation of the sheet laminate (fired multilayer ceramic substrate) were suppressed.

  In addition, among sample numbers 1 to 4 which are samples of the examples, in the case of sample numbers 3 and 4 in which two constraining layer green sheets are disposed on both main surface sides of the substrate sheet laminate, It was confirmed that the amount of warpage was smaller than the samples Nos. 1 and 2 in which one constraining layer green sheet was disposed on each of the main surfaces.

In Example 2, as shown in FIG. 9, only one side region 12a is thicker than the other region 12b, the one side region 12a has a thickness of 0.20 mm, and the other region 12b has a thickness of 0.2 mm. A 10 mm constraining layer green sheet 11 was produced.
It should be noted that the constraining layer green sheet 11 of Example 2 in which only one side region 12a is thicker than other regions 12b can also be efficiently formed by a method according to the method shown in Example 1.
The planar dimensions when viewed from the molding direction were prepared so that the one side region 12a was 27.5 mm and the other region 12b was 122.5 mm. Thereby, when the laminated body after lamination pressure bonding is cut with respect to each edge at a position of 52.5 mm from the center, the width of the one side region 12a is 5 mm and the width of the other region 12b is 100 mm. .

  And the unfired composite laminated body 10 demonstrated below was produced using this green sheet 11 for constrained layers whose one side area | region 12a is thicker than the other area | region 12b.

  First, as shown in FIG. 10, two layers of constraining layer green sheets 11 are provided on both the one main surface side and the other main surface side of the laminate (substrate sheet laminate) 22. The two constraining layer green sheets 11 on the surface side are arranged in a state rotated by 180 °, and the two constraining layer green sheets 11 on the other main surface side are also arranged in a state rotated by 180 °. In addition, when the constraining layer green sheet 11 on the one main surface side and the other main surface side is considered as a set of two layers, the constraining layer green sheet 11 is plane-symmetrical on the one main surface side and the other main surface side. An unfired composite laminate (non-fired composite laminate provided with the requirements of the present invention) 10 provided with a constraining layer 1A having four corners thicker than the central portion.

  As shown in FIG. 11, four layers of constraining layer green sheets 11 are arranged on one main surface side and the other main surface side of the laminate (substrate sheet laminate) 22, respectively. The four constraining layer green sheets 11 on the main surface side are arranged in a state of being rotated by 90 ° in sequence, and the four layers of constraining layer green sheets 11 on the other main surface side are also being rotated in sequence by 90 °. And the constraining layer green sheet 11 on the one main surface side and the other main surface side is considered as a set of four layers, the constraining layer green sheet 11 on one main surface side and the other main surface side. Is a non-fired composite laminate (unfired composite laminate having the requirements of the present invention) 10 provided with a constraining layer 1A having four corners thicker than the central portion.

For comparison, the following unfired composite laminates (a) and (b) were produced in the same manner as described above.
(a) As shown in FIG. 12, only one side region 12a is thicker than the other region 12b on both main surface sides of the one main surface side and the other main surface side of the laminate (sheet laminate for substrate) 22 The constraining layer green sheets 11 are disposed one by one, and the two constraining layer green sheets 11 on one main surface side and the other main surface side are disposed in a state of being rotated by 180 ° relative to each other. When compared with either one of the constraining layers on the surface side and the other main surface side, the unfired for comparison not satisfying the requirement of the present invention that includes the constraining layer 1A having at least four corners thicker than the central portion. Composite laminate 10.

  (b) As shown in FIG. 13, two layers of constraining layer green sheets 11 are provided on each of the principal surface side and the other principal surface side of the laminate (substrate sheet laminate) 22. The two constraining layer green sheets 11 on the one main surface side are arranged in a state where they are rotated by 90 °, and the two constraining layer green sheets 11 on the other main surface side are also rotated by 90 °. An unfired composite laminate 10 disposed in a state where “when at least one of the constraining layers on one main surface side and the other main surface side is viewed, at least four corners are thicker than the central portion. A comparative unfired composite laminate 10 that does not satisfy the requirement of the present invention “comprising a layer”.

And similarly to the case of the said Example, although the board | substrate sheet | seat laminated body 22 sinters each unbaking composite laminated body 10 shown to FIGS. 10-13, the green sheet 11 for constrained layers is not sintered 800 Baking was performed at a temperature of 1050 ° C.
And each multilayer ceramic board | substrate was obtained by removing the constrained layer which remained on the both main surfaces from the composite laminated body after sintering.

  When the amount of warpage was measured by the same method as in Example 1 above, it was manufactured through the step of firing the unfired composite laminate 10 of FIG. 10 and FIG. In the case of the multilayer ceramic substrate, it was possible to obtain a multilayer ceramic substrate with a small amount of warping in accordance with Sample Nos. 1 to 4 of Example 1 above. In the case of the unfired composite laminate 10 of FIG. 10 and FIG. 11, “when one of the constraining layers on one main surface side and the other main surface side is viewed, the thickness of at least four corners is larger than the central portion. This is because the requirement of the present invention “having a thick constraining layer” is satisfied, and the four corners of the substrate sheet laminate can be sufficiently constrained.

  On the other hand, in the case of a multilayer ceramic substrate which is a comparative sample manufactured through the step of firing the unfired composite laminate 10 of FIGS. 12 and 13, the unfired composite laminate 10 of FIGS. It was not possible to obtain a multilayer ceramic substrate with a small amount of warping, such as a multilayer ceramic substrate manufactured through a firing step. This is because the unfired composite laminate 10 of FIG. 12 and FIG. 13 shows that “when one of the constraining layers on one main surface side and the other main surface side is viewed, the thickness of at least four corners is thicker than the central portion. This is due to the fact that the requirement of the present invention “comprising a layer” was not satisfied, and the four corners of the substrate sheet laminate could not be sufficiently restrained.

  In the above-described embodiment, the case where the constraining layers are arranged on both main surface sides of the laminate (substrate sheet laminate) has been described as an example. In some cases, warping and deformation can also be suppressed by disposing only on the one main surface side of the sheet laminate.

  In addition, as a constituent material of the constraining layer green sheet, there is no special restriction as long as it can exhibit the necessary restraining force in the firing step without sintering at the sintering temperature of the substrate sheet laminate, for example, Those containing a glass component can also be used. However, when glass is contained, the removability at the time of removal after the firing step tends to be lowered, so that it is preferable not to contain glass.

  The present invention is not limited to the above embodiments in other respects as well, and relates to the arrangement of the conductors such as the type of material constituting the ceramic substrate, the number of laminated ceramic layers, the internal electrode pattern, etc. Various applications and modifications can be added within the range.

DESCRIPTION OF SYMBOLS 1A Constrained layer 1 Constrained layer green sheet 2a 2 side area 2b Central area 10 Unfired composite laminate 11 Constrained layer green sheet 12a 1 side area 20 Substrate green sheet 21 Conductive pattern 22 Laminate (Sheet laminate for substrate)
30 Doctor blade 31 Concave portion of doctor blade 32 Convex portion of doctor blade 33 Carrier film A Arrow indicating the forming direction L Cut line

Claims (5)

At least one of the one main surface side and the other main surface side of the unfired ceramic molded body that becomes the ceramic substrate after firing is mainly composed of a hardly sinterable ceramic powder that does not sinter at the sintering temperature of the unfired ceramic molded body. A step of forming an unfired composite laminate having a rectangular planar shape in which a constraining layer is disposed;
Firing the unfired composite laminate at a temperature at which the ceramic compact is sintered but the hardly sinterable ceramic powder constituting the constraining layer is not sintered;
A step of removing the constraining layer after the step of firing the unfired composite laminate is completed,
The constraining layer green sheet constituting the constraining layer is a constraining layer green sheet in which the thickness of one side region or two side regions facing each other is made thicker than the other region. A method for producing a ceramic substrate, comprising: forming the unfired composite laminate including a constraining layer having a thicker corner than the center portion.   The unfired ceramic molded body is a laminate formed by laminating a plurality of ceramic green sheets that become ceramic layers after firing, and the ceramic substrate manufactured through the firing step of the unfired composite laminate is a multilayer ceramic substrate The method for producing a ceramic substrate according to claim 1, wherein:   3. The method of manufacturing a ceramic substrate according to claim 1, wherein an unfired composite laminate is formed in which a constraining layer is disposed on both the one main surface side and the other main surface side of the ceramic molded body.   The constraining layer green sheet constituting the constraining layer on the one main surface side and the constraining layer green sheet constituting the constraining layer on the other main surface side are opposed to the one side region or the two. 4. The method for manufacturing a ceramic substrate according to claim 3, wherein the ceramic substrate is disposed in a manner that is plane-symmetric when viewed from the positional relationship of the side regions.   The method for producing a ceramic substrate according to any one of claims 1 to 4, wherein the constraining layer green sheet is a constraining layer green sheet that is integrally formed when the sheet is formed.

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