JP2006253246A - Method of manufacturing multilayer ceramic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer ceramic substrate which offers more multilayering or reduction in size and improvement on a degree of freedom in designing of a multilayer ceramic substrate, which increases a degree of freedom in designing and makes the substrate more compact by electrically connecting different dielectric materials in the direction of the principal plane of a sheet, and which can form the dielectric materials in a required size at a required place compared with the conventional multilayer structure while alleviating the restrictions on the physical properties (calcination shrinking percentage and coefficient of thermal expansion) of the dielectric materials to be combined. <P>SOLUTION: A cutout or crack is formed in a predetermined part of a second green sheet. Then, with the predetermined part kept placed on a second support, other part than the predetermined part is peeled off with a tape. Then, a first green sheet having a punched hole is laid on top of the second support, and the predetermined part is fit into the punched hole to fabricate a composite green sheet composed of different materials. In fabricating the composite green sheet, the predetermined part of the second green sheet is always kept placed on the second support having no hole to prevent the dropout of the inserted green sheet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer ceramic substrate configured by combining a plurality of ceramic materials having different electrical and / or physical characteristics.

  The multilayer ceramic substrate is composed of a plurality of ceramic layers, and wiring conductors are formed between the ceramic layers along the interfaces thereof. Usually, multilayer ceramic substrates are laminated with multiple types of ceramic material green sheets having different electrical and physical properties for multi-functionality and higher performance, and the resulting composite laminate is fired simultaneously. Manufactured. This is because electronic elements such as capacitors and inductors that require different dielectric constant characteristics are integrally formed in the multilayer ceramic substrate.

In order to obtain such a multilayer ceramic substrate, conventionally, the following means have been proposed.
(1) A method of laminating a plurality of types of ceramic layers each containing ceramic materials that give different electrical characteristics. For example, a plurality of types of ceramic layers each including a dielectric ceramic material having different dielectric constants and a ceramic layer including a magnetic ceramic material are laminated (for example, see Patent Document 1).

(2) A method in which a space is formed inside the green sheet laminate before firing, a molded body block before firing is fitted into this space, and then the molded body block and the green sheet laminate are fired simultaneously (for example, (See Patent Documents 2 to 5.)

(3) A space is formed in the green sheet before firing by using a photolithographic method, a different material paste is filled into the space to produce a different material composite green sheet, and a conductor is formed thereon by the same method. A method of stacking and firing (see, for example, Patent Document 6).

(4) A method in which a gap is partially provided in a green sheet before firing, a green sheet of a different material is fitted into the gap, a composite is produced in units of sheets, stacked, and simultaneously fired (see, for example, Patent Document 7). ).

JP 2001-144438 A JP-A-61-288498 Japanese Patent No. 3322199 JP-A-11-163530 Japanese Patent Laid-Open No. 11-87918 Patent No. 30664455 JP 2004-148610 A

  However, the technique described in Patent Document 1 has a low degree of design freedom because the dielectrics are arranged in layers inside the substrate. In addition, since elements conforming to the dielectric constant are formed in the principal surface direction of each layer, a sufficient thickness of the layers must be secured, and the thickness of the entire multilayer ceramic substrate increases.

  In the techniques described in Patent Documents 2 to 5, the degree of freedom of design is low because each member can be connected only in the thickness direction of the substrate. Moreover, it is difficult to insert the molded body block into the space inside the laminate with high accuracy. Further, voids are easily generated between the respective members, and reliability is lacking. Moreover, since the lamination direction of a laminated body and a forming block differs 90 degree | times, it is difficult to adjust the space dimension of a laminated body and a molded object block dimension, and the unnecessary space for that is needed.

  The technique described in Patent Document 6 is expensive because it uses a photolithographic method. Each time the space shape and layout are changed, it becomes necessary to produce a mask, and the lead time becomes longer.

  In the technique described in Patent Document 7, a sheet made of a different material is inserted into a gap provided in a green sheet having a thickness of 50 to 300 μm at the same time as it is cut with a convex mold, but the work is performed in a large amount at a high speed. In this case, the bottom dead center stop position of the convex mold varies, and the green sheet is deformed into a concave shape by embedding air between the convex mold and the green sheet to be inserted, and the sheet having the insertion sheet and the gap is provided. The position is shifted in the thickness direction. If it deviates greatly, the inserted green sheet may fall off. This is particularly noticeable when the size of the inserted green sheet is large and thin. Furthermore, the inserted green sheet tends to fall off when handling the green sheet of the different material composite after insertion. This is also remarkable when the size of the inserted green sheet is large and thin. In addition, just by inserting the green sheet, the paste soaks into the dissimilar material boundary portion of the dissimilar material composite green sheet by subsequent printing, and lowers the insulation of the upper and lower layers after lamination.

  Further, in recent years, a multilayer ceramic substrate is required to be thinned per green sheet in order to increase the number of multilayers or reduce the size and to improve the degree of design freedom.

  Therefore, the object of the present invention is to provide a method for manufacturing a multilayer ceramic substrate. (1) When the green sheet is thicker than 50 μm, the multilayer ceramic substrate is made more multilayered or downsized and the degree of freedom in design is improved. Therefore, it is easy to control the thickness of different-material composite green sheets even if it is made thinner than 50 μm, (2) The different-material green sheets can be accurately inserted into predetermined parts, and (3) Different-material composite greens Of the sheets, green sheets fitted with different materials should not be dropped during the manufacturing process. (4) Even if conductor printing is performed across different material boundaries in different material composite green sheets, gaps in the boundary portions are eliminated. It is possible to prevent the penetration of the conductor, and (5) to reduce the size by handling the green sheet with the support attached. To prevent.

  And after realizing more multilayers or miniaturization of multilayer ceramic substrate and improvement of design flexibility, (1) electrically connect different dielectrics in the sheet main surface direction, and increase design flexibility. (2) The material properties (firing shrinkage rate, thermal expansion coefficient) of the dielectric material formed by combining the dielectric material with the required size only in the necessary part compared with the layered structure of Patent Document 1 The purpose is to relax the restrictions.

The inventors of the present invention have manufactured the different material composite green sheet without punching the support on which the green sheet is placed, so that among the different material composite green sheets, the green sheet fitted with the different material is dropped during the manufacturing process. As a result, the present invention has been completed. That is, the method for producing a multilayer ceramic substrate according to the present invention includes a step of punching a predetermined portion of the first green sheet adhered to the surface of the sheet-like first support with a convex mold to form a punch hole,
Peeling the first support from the first green sheet;
Cutting or cracking the periphery of a predetermined portion of the second green sheet in close contact with the surface of the sheet-like second support;
A step of attaching an adhesive tape punched through a hole of substantially the same shape corresponding to a predetermined portion of the second green sheet to the second green sheet so that the hole and the predetermined portion overlap;
The adhesive tape is peeled off from the second green sheet, and a portion other than the predetermined portion of the second green sheet is peeled off from the second support, and the predetermined portion of the second green sheet is formed on the surface of the second support. A process of making only the close contact,
Stacking the first green sheet on the second support so that a predetermined portion of the second green sheet is inserted into the punching hole of the first green sheet, and forming a different material composite green sheet;
Pressurizing the different material composite green sheet to eliminate the gap between the different material boundaries; and
Forming a green sheet laminate including at least one different material composite green sheet;
Firing the green sheet laminate;
It is characterized by having.

  The method for manufacturing a multilayer ceramic substrate according to the present invention includes a case where one or more green sheets having a thickness of 5 μm or more and less than 50 μm are used as the first green sheet. This is for increasing the number of multilayered ceramic substrates or miniaturizing them and improving the degree of freedom in design.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, the second green sheet includes using a green sheet temporarily stacked in two or more layers and having an internal conductor layer interposed between the layers. As a second green sheet to be inserted into the first green sheet, a green sheet in which two or more layers are temporarily stacked and an internal conductor layer is interposed between the layers is provided. The element can be fitted.

  The method for manufacturing a multilayer ceramic substrate according to the present invention includes a case of including a step of forming a via hole in one or both of the first green sheet and the second green sheet. The formation of the via hole in the first green sheet is performed either on the first green sheet portion of the dissimilar material composite green sheet or on the first green sheet before the second green sheet is fitted. Also good. The formation of the via hole in the second green sheet is performed on the second green sheet portion of the dissimilar material composite green sheet or on the second green sheet before the second green sheet is fitted. Also good. The first green sheet becomes a base substrate by firing, and the via hole provided therein can provide a three-dimensional circuit in order to ensure conduction between the stacked substrates. Of course, a via hole can also be formed on the second green sheet side.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, it is preferable to include a step of printing a conductor paste on the dissimilar material composite green sheet. Here, in the step of printing the conductor paste on the different material composite green sheet, it is more preferable to print the conductor paste across the boundary between the first green sheet and the second green sheet. Since the conductor paste is printed after the second green sheet is fitted in a predetermined position of the first green sheet, the conductor paste can be printed across the boundary between the first green sheet and the second green sheet. Therefore, the wiring layer can be designed very flexibly.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, when the green sheet laminate is formed, the predetermined portion of the first green sheet is formed so that the second green sheets have portions that overlap each other in the stacking direction. In addition, it includes a case where a conductor paste is printed on the surface of the second green sheet inserted in the predetermined portion, and an internal conductor layer is interposed between the layers of the second green sheets. A multilayer element such as a multilayer capacitor element can be disposed inside the multilayer ceramic substrate.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, it is preferable that the first green sheet and the second green sheet are formed of materials having different dielectric constants after firing. This is because capacitor elements and inductor elements are formed in the same ceramic substrate. In the present invention, each ceramic layer in the multilayer ceramic substrate is simply referred to as a ceramic substrate in order to distinguish it from the multilayer ceramic substrate that is the laminate.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, it is preferable that the first green sheet and the second green sheet have the same thickness. Although it is not necessary that the thickness of each ceramic substrate to be laminated is the same, the occurrence of delamination can be suppressed by making the surface (interface) flat in each ceramic substrate.

  In the method for manufacturing a multilayer ceramic substrate according to the present invention, the first green sheet and the second green sheet may have the same press compression rate and the same firing shrinkage and thermal expansion coefficient during firing. preferable. Peeling and cracking are suppressed.

  The ceramic substrate is preferably a low-temperature fired (hereinafter referred to as LTCC) substrate. The LTCC substrate can be easily formed as a multilayer substrate having electronic circuit elements or wirings therein, and the density and size of the device can be reduced.

  The manufacturing method of the multilayer ceramic substrate according to the present invention is less than 50 μm in order not only when the green sheet is thicker than 50 μm but also for increasing the number of multilayered ceramic substrates or reducing the size and improving the design flexibility. Even if the thickness is reduced, among the different-material composite green sheets, the green sheets fitted with different materials are not dropped during the manufacturing process, so that the yield is good and the dimensional accuracy is also good. Further, since different dielectrics can be electrically connected in the sheet main surface direction, the degree of freedom in circuit design is high and the substrate itself can be made compact. In addition, a dielectric having a required size can be formed only in a necessary portion, and a dielectric that can be combined relatively freely can be selected without being restricted by a firing shrinkage ratio or a thermal expansion coefficient. Furthermore, since different dielectrics are accurately fitted to predetermined portions, the occurrence of peeling and cracking is also suppressed.

  Hereinafter, although an embodiment is shown to the present invention and the present invention is explained in detail, the present invention is limited to these descriptions and is not interpreted. In addition, the same code | symbol is attached | subjected to the same member in the figure. First, a method for manufacturing a multilayer ceramic substrate according to this embodiment will be described. FIG. 1 is a schematic view showing a manufacturing process of the dissimilar material composite green sheet used in this embodiment.

  As shown in FIG. 1A, a first green sheet 1 is formed in close contact with the surface of a first support 2 such as a plastic sheet. The plastic sheet may be any sheet as long as it has a smooth surface. For example, it is a PET (polyethylene terephthalate) sheet. The thickness of the first support 2 is preferably a thickness that does not deform during the process and is easy to handle, and is generally 50 to 150 μm. As a method for producing a green sheet, for example, as a dielectric paste, a ceramic powder and an organic vehicle are mixed to form a slurry, and a film is formed on a resin sheet such as a PET sheet by a sheet molding method such as a doctor blade method. Get. In the case of obtaining a glass ceramic substrate, a slurry in which ceramic powder, glass powder and an organic vehicle are mixed is used. An organic vehicle is obtained by dissolving a binder in an organic solvent. Consists of a plasticizer. In addition, peptizers, wetting agents and the like may be added. The content of the organic vehicle is not particularly limited, and may be a normal content, for example, 1 to 5% by weight for the binder and 10 to 50% by weight for the solvent.

  In addition to the organic paint containing an organic vehicle, a water-soluble paint in which a water-soluble binder, a dispersant, and the like are dissolved in water may be used. Here, the water-based binder is not particularly limited, and may be appropriately selected from polyvinyl alcohol, cellulose, water-soluble acrylic resin, emulsion and the like.

  As the dielectric material of the dielectric paste, a material constituting the main component and the subcomponent is used according to the composition of the dielectric ceramic composition. The raw material form is not particularly limited, and an oxide constituting the main component and subcomponents and / or a compound that becomes an oxide by firing is used. These raw materials may be either a liquid phase synthesis method or a solid phase method. The powder obtained from may be sufficient. In addition, as a compound which becomes an oxide by baking, carbonate, nitrate, oxalate, an organometallic compound, etc. are illustrated, for example. Of course, you may use together an oxide and the compound which becomes an oxide by baking. What is necessary is just to determine content of each compound in a dielectric raw material so that it may become a composition of the above-mentioned dielectric ceramic composition after baking.

  When producing a glass ceramic substrate which is an LTCC substrate, the glass component and the ceramic component may be appropriately selected based on the intended relative dielectric constant and firing temperature, and alumina (crystals) obtained by firing at 1000 ° C. or less. And a substrate made of silicon oxide (glass phase). In addition, magnesia, spinel, silica, mullite, forsterite, steatite, cordierite, strontium feldspar, quartz, zinc silicate, zirconia, titania and the like can be used as the ceramic component. As the glass component, borosilicate glass, borosilicate barium glass, strontium borosilicate glass, zinc borosilicate glass, potassium borosilicate glass, and the like can be used. The glass component is preferably 60 to 80% by volume, and the ceramic component as an aggregate is preferably 40 to 20% by volume. If the glass component is out of the above range, it is difficult to form a composite composition, and strength and sinterability are reduced.

  The thickness of each first green sheet is determined by the use of elements, wirings, and the like that are formed in the substrate after firing, and is generally 20 to 245 μm. For example, in the case of an application in which many inductor elements are desired, it is preferable to reduce the thickness of the first green sheet. Moreover, when forming wiring with a high Q value or when forming a heat dissipation via hole, it is preferable to increase the thickness of the first green sheet. The number of stacked first green sheets is not particularly limited, but is 4 to 50. However, it is desirable to make the multilayer ceramic substrate thinner in order to reduce the size by further multilayering or thinning the multilayer ceramic substrate. In some cases, a thin ceramic substrate may be included in the multilayer ceramic substrate to improve the degree of freedom in circuit design. This embodiment will be described later in each step of FIGS. 1 (1) to (11), particularly in FIGS. 1 (8) to (9), which are steps of inserting a second green sheet into a predetermined portion of the first green sheet. Thus, in order to prevent the second green sheet 10a from falling off, the second green sheet 10a is always attached to the second support 9 without forming a punching hole in the second support 9 of the second green sheet in the process. Put it on. As a result, the first green sheet can be reduced to a thickness of 5 to 20 μm as well as a thickness of 20 to 245 μm. In the present embodiment, the thickness of the first green sheet can be 5 to 245 μm. However, when the ceramic substrate is thinned, the thickness is 5 μm or more and less than 50 μm, depending on the application, for example, 5 μm or more and less than 20 μm, 20 The case where it is less than 50 μm or less than ˜40 μm or 40 μm is included. In the multilayer ceramic substrate, the thickness of each layer may be set differently. For example, each green thinned to a thickness of 5 μm or more and less than 50 μm, for example, 5 μm or more, less than 20 μm, 20-40 μm or more than 40 μm and less than 50 μm. Each sheet may be included as one layer of the green sheet laminate.

  Next, as shown in FIGS. 1 (2) and (3), the predetermined portion 3 of the first green sheet 1 is held with the convex mold 4 while keeping in close contact with the surface of the sheet-like first support 2. A punching hole 6 is formed by punching. The shape of the punching hole 6 is determined by the shapes of the convex mold 4 and the mold 5.

  Next, as shown in FIG. 1 (4), the first support 2 is peeled from the first green sheet 1.

  Next, the second green sheet 10 is formed on the second support 9 such as a PET sheet by the same method as the first green sheet. The thickness of the second support 9 is preferably a thickness that does not deform during the process and is easy to handle, and is generally 50 to 150 μm. Here, the second green sheet 10 is preferably formed of a material having a different dielectric constant after firing as compared to the first green sheet 1. The dielectric constant of the second green sheet 10 is appropriately selected according to the characteristics of the capacitor element and inductor element to be formed. However, it is preferable that the first green sheet 1 and the second green sheet 10 have the same thickness in order to finally form a flat different material composite green sheet 11. Furthermore, the composition of the dielectric paste can be adjusted so that the first green sheet 1 and the second green sheet 10 have the same press compression ratio and the same firing shrinkage and thermal expansion coefficient during firing. preferable. However, according to the method of manufacturing the multilayer ceramic substrate according to the present embodiment, compared to the case where the dielectric material is changed at the layered structure level, a different dielectric can be formed in a necessary size only in a necessary portion. Restrictions on material properties (firing shrinkage ratio, thermal expansion coefficient) of the dielectric to be combined are loosened. Examples of combinations that satisfy these characteristics include the following combinations of material compositions.

If it is - (glass _{(SiO 2 -B 2 O 3 -A1} 2 O 3 -MgO-CaO-SrO) A1 2 O 3) for example the composition of the dielectric material of the first green sheet, an aluminum oxide-based dielectric material The composition of the dielectric material of the second green sheet is preferably the following composition. That is, aluminum oxide-titanium oxide based dielectric material (A1 ₂ O ₃ —TiO ₂ —glass (SiO ₂ —B ₂ O ₃ —A1 ₂ O ₃ —MgO—CaO—SrO)), aluminum oxide—titanium oxide—oxidation A strontium-based dielectric material (SiO ₂ —A 1 ₂ O ₃ —La ₂ O ₃ —B ₂ O ₃ —TiO ₂ —Bi ₂ O ₃ —Nd ₂ O ₃ —SrO) or the like is preferable.

  Next, as shown in FIG. 1 (5), a cut or crack 60 is made by punching with a convex die 4 at the periphery of the predetermined portion 7 of the second green sheet 10 in close contact with the surface of the second support 9. The shape of the predetermined portion 7 is determined by the shapes of the convex mold 4 and the mold 5. The edge of the pressing surface of the convex mold 4 may be raised so that the green sheet can be easily cut. In addition, when the predetermined portion 7 of the second green sheet 10 is punched, the predetermined portion 7 is pushed to cause a density difference or a step at the boundary between the predetermined portion 7 and the other portion of the second green sheet. In some cases, a crack 60 may enter the periphery of the predetermined portion 7. By forming these cuts or cracks, the predetermined portion 7 can be easily extracted at the periphery of the predetermined portion 7 in the step of FIG.

  Next, as shown in FIG. 1 (6), the adhesive tape 8 in which the hole 12 having the same position and substantially the same shape is punched out in correspondence with the predetermined portion 7 of the second green sheet 10, and the hole 12 and the predetermined portion 7 are formed. Affix on the second green sheet 10 so as to overlap. The hole 12 may be slightly larger than the dimension of the predetermined portion 7. As the pressure-sensitive adhesive tape, for example, a pressure-sensitive adhesive tape manufactured by Sumitomo 3M Limited was used, and pressure-sensitive adhesive tapes having different adhesive strengths were selected according to conditions such as the size of the green sheet and the predetermined portion.

  Next, as shown in FIG. 1 (7), the adhesive tape 8 is peeled off, and the portion 10 b other than the predetermined portion of the second green sheet 10 is peeled off from the second support 9. It can be easily removed leaving the predetermined portion 10a with the notch or crack 60 made by the convex mold 4 shown in the step of FIG. As a result, only the predetermined portion 10 a of the second green sheet is in close contact with the surface of the second support 9.

Next, as shown in FIG. 1 (8), the first green sheet 1 is placed on the second support 9 so that the predetermined portion 10 a of the second green sheet 10 is inserted into the punching hole 6 of the first green sheet 1. The different material composite green sheet 11 is formed by overlapping. Thereby, as shown in FIG. 1 (9), the different material composite green sheet 11 is obtained in which the predetermined portion 10 a of the second green sheet 10 is fitted into the punching hole 6 of the first green sheet 1 with high accuracy. Then, the different material composite green sheet 11 is pressed to eliminate the gap between the different material boundary portions 14. The pressurizing condition is appropriately changed depending on the thickness of the different material composite green sheet 11. For example, the pressure for pressure bonding is 3 to 8 MPa, the heating temperature is 35 to 90 ° C., and the pressure bonding time is 3 to 10 seconds. It is. Preferably, the temperature is 85 ° C., 4.9 MPa (50 kg / cm ² ), and 5 seconds. By this pressurization, the gap between the different material boundary portions 14 is eliminated, and the different material composite green sheet 11 is integrated. Thereby, the dissimilar material composite green sheet 11 is stably placed on the second support 9, and the predetermined portion 10a of the inserted second green sheet 10 is prevented from falling off during the process. Further, even if the second support 9 is peeled off in the subsequent steps, the different material composite green sheet 11 is integrated without any gap between the different material boundary portions 14, so that the inserted second green sheet 10 is not integrated. The predetermined portion 10a is prevented from falling off. Further, when the conductor paste is printed, the conductor paste does not penetrate into the gap between the different material boundary portions 14. Note that the step of eliminating the gap is preferably performed in order to prevent the conductor paste from penetrating into the gap even when it is thick, regardless of the thickness of the different-material composite green sheet 11.

  As shown in FIG. 1 (10), before printing the conductor paste, the first green sheet 1 side of the different material composite green sheet 11 adhered on the second support 9 or the predetermined portion 10a side of the second green sheet. A step of forming the via hole 15 by a via hole forming method such as laser processing may be added to one or both of them. The formation of the via hole 15 on the first green sheet 1 side is not limited to the formation of the dissimilar material composite green sheet 11, and may be performed, for example, after the formation of the first green sheet 1 (after FIG. 1 (1)). good. The formation of the via hole on the second green sheet 10 side is not limited to the formation after the dissimilar material composite green sheet 11 is formed, and may be performed, for example, after the formation of the second green sheet 10 (after FIG. 1 (7)).

  Next, as shown in FIG. 1 (11), a conductive paste is printed on the surface of the different material composite green sheet 11 and the via hole 15 to form a conductor layer 16 and a via 17. This is a sheet 18. Since the conductive paste is printed after the dissimilar material composite green sheet 11 is formed, printing can be performed on either the first green sheet 1 side or the surface of the predetermined portion 10a side of the second green sheet fitted therein. . Moreover, it is possible to print the conductor paste across the boundary between the first green sheet 1 side and the predetermined portion 10a side of the second green sheet. Therefore, regardless of the fitting position of the predetermined portion 10a of the second green sheet in the different material composite green sheet 11, the pattern of the wiring layer and the electrode can be freely printed.

  The conductive paste is prepared by kneading a conductive material made of various conductive metals or alloys such as Ag, Ag—Pd alloy, Cu, Ni, and the above-described organic vehicle. The content of the organic vehicle is not particularly limited, and may be a normal content, for example, 1 to 5% by weight for the binder and 10 to 50% by weight for the solvent. Each paste may contain additives selected from various dispersants, plasticizers, and the like as necessary.

  Then, the 2nd support body 9 is peeled off from the different material composite green sheet 11 (not shown).

  A different material composite green sheet is formed by the above steps. Next, a plurality of various green sheets are stacked so as to include at least one dissimilar composite green sheet, and a main sheet is pressed in the stacking direction to form a green sheet stack. At this time, in addition to the composite green sheet of different materials, the first green sheet and the second green sheet may be mixed to form a green sheet laminate. Although the pressure of this pressurization is not specifically limited, Preferably it is 40-100 MPa, The heating temperature is 35-80 degreeC.

  Thereafter, the binder removal treatment and the firing treatment are performed, and the fired multilayer ceramic substrate 100 shown in FIG. 2 is obtained. FIG. 2 is a schematic cross-sectional view showing one embodiment of the multilayer ceramic substrate according to the present embodiment.

The firing temperature is determined by the material of the green sheet and is not particularly limited, but is generally 850 to 1000 ° C. The firing atmosphere may be determined as appropriate according to the type of conductive material in the conductor paste, but when a base metal such as Cu, Ni, Cu alloy, Ni alloy or the like is used as the conductive material, a reducing atmosphere should be used. The oxygen partial pressure in the firing atmosphere is preferably 10 ⁻¹⁰ to 10 ⁻³ Pa, more preferably 10 ⁻⁷ to 10 ⁻³ Pa. If the oxygen partial pressure during firing is too low, the conductive material of the internal electrode tends to break due to abnormal sintering, and if the oxygen partial pressure is too high, the internal electrode tends to be oxidized.

  Thereafter, the circuit pattern 38 and the terminals 33 are printed on the surface of the multilayer ceramic substrate 100. The circuit pattern may be printed before the multilayer ceramic substrate 100 is fired.

  The multilayer ceramic substrate 100 can form a dielectric layer 31 and a dielectric layer 35 different from the dielectric layer 31 in a desired position and size in the substrate, and electrical connection in the main surface direction of each ceramic substrate. 39 can also be formed easily. In FIG. 2, the electrical connection 39 in the main surface direction of each ceramic substrate includes the outer electrode layer 36 and is integrally printed. Further, it is easy to form the conductive through hole 34 as in the prior art.

  For example, the multilayer ceramic substrate uses a first green sheet having a thickness of 5 μm or more and less than 50 μm to form a different material composite green sheet having the same thickness, and includes one or more different material composite green sheets. Then, the green sheet laminate is fired. At this time, the green sheet shrinks to 60 to 72% in the thickness direction and approximately two-thirds of the thickness by firing. That is, the dissimilar material composite green sheet having a thickness of 5 μm or more and less than 50 μm becomes a dissimilar material composite ceramic substrate having a thickness of 3.3 μm or more and less than 33.3 μm by sintering, and is sintered with the upper and lower ceramic substrates. Therefore, such a multilayer ceramic substrate has one or more layers of thin dissimilar composite ceramic substrates of 3.3 μm or more and less than 33.3 μm. In addition, the shrinkage rate in the substrate main surface direction is 80 to 90%. The multilayer ceramic substrate may be composed of, for example, a composite ceramic substrate of different materials having a size of 3.3 μm or more and less than 13.3 μm, 13.3 to 26.7 μm, or more than 26.7 μm and less than 33.3 μm. The thickness of each layer may be set to be different from 3.3 μm or more and less than 33.3 μm, for example, 3.3 μm or more and less than 13.3 μm, 13.3 to 26.7 μm, or more than 26.7 μm. Each layer thinned to be less than 3 μm may be included as one layer of the multilayer ceramic substrate. The multilayer ceramic substrate may have a layer made of a composite ceramic substrate of different material with a thickness of 3.3 μm or more and less than 33.3 μm, a layer with a thickness of 33.3 μm or more and 163 μm or less, or a layer with a thickness exceeding 163 μm. good. This thick layer includes a fired layer of a different composite green sheet, a fired layer of only the first green sheet, and / or a fired layer of only the second green sheet.

  A multilayer ceramic substrate including a thin layer substrate of 3.3 μm or more and less than 33.3 μm is manufactured only after a thin different material composite green sheet can be stably manufactured as in the method of manufacturing a multilayer ceramic substrate according to this embodiment. It can be. In the obtained multilayer ceramic substrate, the conductor layer is provided in the portion of the interface between the different ceramic composite substrates that crosses the boundary between the first ceramic substrate and the second ceramic substrate, thereby improving the degree of freedom in circuit design. ing.

  The present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the present invention.

  FIG. 3 shows a schematic cross-sectional view when a multilayer capacitor is formed in a multilayer ceramic substrate. Thus, when forming a multilayer capacitor in the multilayer ceramic substrate 200, the following process is performed. That is, when the green sheet laminated body is formed, the respective green sheets are formed by aligning the punched hole positions of the first green sheets so that the second green sheets overlap each other in the stacking direction. A conductor paste is printed on the surface of the second green sheet fitted in the punched hole. Thereby, when the multilayer ceramic substrate 200 is formed, the internal conductor layer 24 is interposed between the fired layers 22 of the second green sheet. In addition, the outer electrode layer 23 is formed. Thereby, a multilayer capacitor can be formed in the multilayer ceramic substrate 200. Since the internal electrode layer 24 can freely print a wiring layer or an electrode pattern regardless of the fitting position of the second green sheet in the dissimilar material composite green sheet, the electrical connection between the internal electrode layers is easy. is there.

  FIG. 4 is a view showing a structural example of the green sheet laminate according to the present embodiment. For example, the embodiment shown in FIG. 1 is a case where a second green sheet 51 having the same thickness as the first green sheet 50 is inserted as shown in FIG. On the other hand, as shown in FIG. 4B, the thicknesses of the second green sheets 52a and 52b are each half of the thickness of the first green sheet 50, and temporarily stacked in two layers, What provided the internal conductor layer 37 between the layers may be inserted into the first green sheet 50. Alternatively, as shown in FIG. 4C, the thickness of the second green sheets 53a, 53b, 53c is set to one third of the thickness of the two first green sheets 50, and then temporarily stacked in three layers. In addition, a structure in which the inner conductor layers 37 a and 37 b are provided between the layers may be inserted into the first green sheet 50. The same applies when four or more second green sheets are stacked and inserted into a smaller number of first green sheets. 4B and 4C, the thicknesses of the second green sheets 52a and 52b or the second green sheets 53a, 53b, and 53c are equal to each other, but may be different from each other.

Example 1
In accordance with the process shown in FIG. 1, after firing, a first green sheet having a composition (SiO ₂ —B ₂ O ₃ —A1 ₂ O ₃ —MgO—CaO—SrO) having a dielectric constant ε of 7.3, and firing Thereafter, the composition having a dielectric constant ε of 21.1 (SiO ₂ —A 1 ₂ O ₃ —La ₂ O ₃ —B ₂ O ₃ —BaO—TiO ₂ —Bi ₂ O ₃ —Nd ₂ O ₃ —SrO) Two green sheets were used to produce a composite green sheet of different materials. Thirty different composite green sheets each having a thickness of 240 μm, 120 μm, 60 μm, 30 μm, and 10 μm were prepared. The size of the inserted second green sheet was a 3 mm square, and 42 second green sheets were inserted so as to be evenly arranged in one sheet. In the step of FIG. 1 (9), the dropout rate of the inserted second green sheet was evaluated. That is, it is the dropout rate of the insertion portions of 1260 second green sheets inserted into 30 different-material composite green sheets of each thickness. This was designated Example 1. On the other hand, in the punching hole of the first green sheet without the support obtained in FIG. 1 (4), a second green sheet without an untreated support without being cut is placed on the support and punched by punching. The case of insertion was used as a comparative example. Also in the comparative example, 30 different-material composite green sheets having thicknesses of 240 μm, 120 μm, 60 μm, 30 μm, and 10 μm were prepared, respectively, and inserted into 30 different-material composite green sheets of each thickness. The dropout rate of the insertion part of the second green sheet was evaluated. The results are shown in Table 1.

In Example 1, even if the sheet thickness was as thick as 240 μm or as thin as 10 μm, for example, the process proceeded on the second support without punched holes, so the dropout rate was 0%. Therefore, it can be seen that a composite green sheet of different materials with high yield and high accuracy can be produced. On the other hand, in the comparative example, since there is no support, the dropout rate is 6.0% even if the sheet thickness is 120 μm, for example. If the sheet thickness is, for example, 60 μm, the drop-off rate is 28.8%, and considering the yield, it can be determined that a dissimilar composite green sheet cannot be produced economically. Furthermore, if the sheet thickness is 30 μm, for example, a dissimilar composite green sheet could not be produced. If the sheet thickness was 10 μm, for example, the second green sheet could not be inserted. Therefore, when the sheet thickness is 60 μm or less, for example, the superiority of Example 1 having the process of always using the support is shown.
(Example 2)

A multilayer ceramic substrate having the capacitor element shown in FIG. 3 was formed, and the capacitance and IR were measured. The thickness of the first green sheet fitted with the second green sheet was 30 μm, and the thickness of the first green sheet not fitted with the second green sheet was 60 μm. The fired layer 21 of the first green sheet has a composition (BaO—A1 ₂ O ₃ —SiO ₂ —B ₂ O ₃ ) having a dielectric constant ε of 5.9 after firing, and the fired layer 22 of the second green sheet is After firing, a composition (BaO—Nd ₂ O ₃ —TiO ₂ —B ₂ O ₃ —CaO—ZnO) having a dielectric constant ε of 72.3 was obtained. The size after firing of the second green sheet portion fitted in the first green sheet is 2.57 mm × 2.57 mm × 20 μm, and the size of the internal conductor layer (internal electrode) 24 is 1.71 mm × 1.71 mm. did. The first green sheet in which the second green sheet was not fitted had a thickness after firing of 40 μm. The outer electrode is 23. This was designated Example 2. The thickness of the multilayer ceramic substrate after firing was 220 μm.

Regarding Example 2, the relationship between the capacitor capacity and the insulation resistance is shown in FIG. 5 with a capacity measurement frequency of 1 kHz, a measurement temperature of 25 ° C., and an IR measurement applied voltage of 10 V. The measuring device used was a PRECISION LCR METER, model number: 4284A manufactured by HP. Referring to FIG. 5, it had an insulation resistance value of 10 ⁹ Ω or more, and had characteristics of a certain quality or higher.

The schematic diagram which shows the manufacturing process of the dissimilar-material composite green sheet used by this embodiment was shown. The schematic sectional drawing which shows one form of the multilayer ceramic substrate which concerns on this embodiment was shown. A schematic cross-sectional view when a multilayer capacitor is formed in a fired multilayer ceramic substrate is shown. It is a figure which shows the structural example of the green sheet laminated body which concerns on this embodiment, (a) is the case where the 2nd green sheet of the same thickness as a 1st green sheet is inserted, (b) is a 1st green sheet of one layer When the second green sheet having two layers temporarily stacked is inserted, (c) shows the case where the second green sheet having three layers temporarily stacked is inserted into the first green sheet having two layers. Regarding Example 2, the relationship between the capacitor capacity and the insulation resistance when the capacity measurement frequency is 1 kHz, the measurement temperature is 25 ° C., and the IR measurement applied voltage is 10 V is shown.

Explanation of symbols

1, 50, first green sheet 2, first support 3, predetermined portion of first green sheet 4, convex mold (incision processing / insertion processing machine)
5, mold 6, punching hole 7, predetermined portion 8 of second green sheet, adhesive tape 9, second support 10, 10a, 10b, 51, 52a, 52b, 53a, 53b, 53c, second green sheet 11 , Different material composite green sheet 14, different material boundary 15, via hole 16, conductor layer 17, via 18, different material composite green sheet (after conductor paste printing)
21, 30, fired layers 22, 31, 35 of the first green sheet, fired layer (dielectric layer) of the second green sheet
23, 36, conductor layer (outer electrode layer)
24, 37, inner conductor layer 32 wiring layer 33, terminal 34, through hole 35, dielectric layers 37, 37a, 37b, inner conductor layer 38, circuit pattern 39, electrical connection 60, notch or crack 100, 200, Multilayer ceramic substrate

Claims (10)

A step of punching a predetermined portion of the first green sheet adhered to the surface of the sheet-like first support with a convex mold to form a punching hole;
Peeling the first support from the first green sheet;
Cutting or cracking the periphery of a predetermined portion of the second green sheet in close contact with the surface of the sheet-like second support;
A step of attaching an adhesive tape punched out of a hole having the same position and substantially the same shape corresponding to a predetermined portion of the second green sheet to the second green sheet so that the hole and the predetermined portion overlap;
The adhesive tape is peeled off from the second green sheet, and a portion other than the predetermined portion of the second green sheet is peeled off from the second support, and the predetermined portion of the second green sheet is formed on the surface of the second support. A process of making only the close contact,
Stacking the first green sheet on the second support so that a predetermined portion of the second green sheet is inserted into the punching hole of the first green sheet, and forming a different material composite green sheet;
Pressurizing the different material composite green sheet to eliminate the gap between the different material boundaries; and
Forming a green sheet laminate including at least one different material composite green sheet;
Firing the green sheet laminate;
A method for producing a multilayer ceramic substrate, comprising:   2. The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein at least one green sheet having a thickness of 5 μm or more and less than 50 μm is used as the first green sheet.   The method for producing a multilayer ceramic substrate according to claim 1 or 2, wherein a green sheet that is temporarily stacked in two or more layers and an internal conductor layer is interposed between the layers is used as the second green sheet.   4. The method of manufacturing a multilayer ceramic substrate according to claim 1, further comprising a step of forming a via hole in one or both of the first green sheet and the second green sheet.   5. The method of manufacturing a multilayer ceramic substrate according to claim 1, further comprising a step of printing a conductive paste on the different material composite green sheet.   6. The multilayer ceramic substrate according to claim 5, wherein in the step of printing the conductor paste on the different composite green sheet, the conductor paste is printed across the boundary between the first green sheet and the second green sheet. Manufacturing method.   When the green sheet laminate is formed, the predetermined portions of the first green sheets are aligned so that the second green sheets overlap each other in the stacking direction, and the second green sheets are inserted into the predetermined portions. 7. The multilayer ceramic substrate according to claim 1, wherein a conductive paste is printed on a surface of the green sheet, and an internal conductor layer is interposed between the second green sheets. Manufacturing method.   The multilayer ceramic according to claim 1, wherein the first green sheet and the second green sheet are formed of materials having different dielectric constants after firing. A method for manufacturing a substrate.   9. The method of manufacturing a multilayer ceramic substrate according to claim 1, wherein the first green sheet and the second green sheet have the same thickness.   The said 1st green sheet and the said 2nd green sheet have comparable press compression rate, and the same baking shrinkage rate and thermal expansion coefficient at the time of baking, The 1, 2, 3, 4 characterized by the above-mentioned. A method for producing a multilayer ceramic substrate according to 5, 6, 7, 8 or 9.

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