JP4205049B2 - Method for manufacturing ceramic green sheet and method for manufacturing electronic component using ceramic green sheet - Google Patents

Description

  The present invention relates to a method for manufacturing an electronic component, particularly a so-called multilayer ceramic formed by laminating ceramics, and a method for manufacturing a so-called ceramic green sheet used therefor. Specific examples of the multilayer ceramic electronic component described here include a multilayer ceramic capacitor, a multilayer ceramic inductor, an LC composite component incorporating these, an EMC-related component, and the like.

  In recent years, with the miniaturization and rapid spread of electronic devices such as mobile phones, there is a need for higher-density mounting and higher performance for electronic components used therefor. In particular, multilayer ceramic electronic components used as passive elements are required to be thinned, multi-layered, and uniform in each layer in order to meet such requirements. Consideration is required.

  A conventional manufacturing method used for manufacturing the above-described ceramic multilayer electronic component, for example, a multilayer ceramic capacitor having electrodes formed therein, and a technique capable of meeting these requirements is a so-called metal-ceramic integrated firing technique. Here, this metal-ceramic integrated firing technique will be briefly described. In this technique, first, a plurality of electrodes are formed simultaneously on the surface of a so-called ceramic green sheet using a conductive paste made of metal powder and an organic binder.

  Subsequently, a plurality of simple ceramic green sheets, ceramic green sheets after electrode formation, and the like are laminated to obtain a ceramic laminate. These electrodes serve as internal electrodes of the finished ceramic multilayer electronic component. Furthermore, the said ceramic laminated body is pressurized in the thickness direction, and the adhesiveness between green sheets is improved. The laminated body that has been brought into close contact is cut and separated into a predetermined size, and further fired. A ceramic multilayer electronic component can be obtained by appropriately forming external electrodes on the outer surface of the obtained sintered body.

JP-A-9-115766 JP-A-4-215414

  In recent years, the ceramic multilayer electronic components described above are required to be further reduced in size and thickness, and it is necessary to further reduce the thickness of a dielectric layer such as ceramic sandwiched between internal electrodes. Therefore, it is required to perform the above-described process by making the ceramic green sheet, which is a material of the ceramic laminate, thinner. In order to meet these requirements, the thickness of the thinnest ceramic green sheet currently used is about 2 to 3 μm.

  However, the thickness of the electrodes printed on these ceramic green sheets is about 1.5 to 2.0 μm. For this reason, when the ceramic laminate is obtained, the thickness of the portion where the internal electrodes overlap is extremely larger than the portion where the internal electrodes do not exist, and a partial step tends to occur. In addition, due to the step, there is a possibility that stacking deviation occurs when the green sheets are stacked.

As described above, pressurization in the thickness direction is performed after the formation of the laminated body, but the above-described step is preferably substantially eliminated by this pressurization step. However, in order to press-contact the green sheet and the internal electrode, for example, a press pressure of 1 ton / cm ² is required, and improvement in process is required. Furthermore, since these pressures are locally applied only to the portion where the internal electrodes overlap, there is a risk of insufficient pressure contact or deformation after pressurization in other regions. In addition, such local application of pressure has been considered to cause a delamination phenomenon called so-called delamination in the laminated body after sintering.

  Such deformation in the laminated body has caused a phenomenon such as variation in capacitance in a laminated ceramic capacitor. Such a problem facilitates the occurrence of variation in electrical characteristics or the expansion of variation in ceramic multilayer electronic components such as small and highly integrated multilayer ceramic inductors, LC composite components, and EMC related components.

  The technique disclosed in the above-described Patent Document 1 is a method devised to suppress the occurrence of such a step. Specifically, when an electrode is formed on a green sheet by screen printing, a conductive paste used for this is formed from an organic binder having a water repellent function and a metal powder. In addition, after forming the electrode, an aqueous ceramic slurry is applied thereon, and the slurry is repelled from above the electrode by the water repellent function, thereby forming a ceramic sheet for filling the step around the electrode pattern. It is said.

  However, in this technique, a gap is also generated between the side surface of the internal electrode and the aqueous slurry, and there is a risk of stacking deviation due to this. In addition, the adhesion strength at the interface between the water-repellent electrode surface and the ceramic green sheet pressed against the surface may be inferior to the conventional adhesion strength between the electrode and the sheet. Furthermore, in the region surrounded by the water-repellent electrode, it is considered that the aqueous slurry has a high tendency to increase the thickness due to the surface tension, and there is a possibility that the lamination accuracy is lowered due to this.

  Patent Document 2 discloses a technique for reducing the occurrence of a step on the sheet due to the electrode thickness by forming a recess in advance in the electrode forming portion on the ceramic green sheet and embedding a conductive paste in the recess by screen printing. Is disclosed. However, when the green sheet is thin, the green sheet follows the convex portion of the base on which the green sheet is formed, and the green sheet has a convex portion formed on the opposite surface of the concave portion forming surface corresponding to the concave portion forming position.

  For this reason, when the screen printing which embeds an electroconductive paste in the said recessed part is performed, the said recessed part may deform | transform and a problem may arise in the formation precision, formation position, etc. of a recessed part. Accordingly, it is practically difficult to match the formation accuracy of the recesses and the electrode formation accuracy by screen printing, and a step or a gap is formed on the sheet due to the difference in position accuracy or displacement in the individual formation. There is a risk. Furthermore, the presence of the convex portion promotes the generation of a molding density difference during the lamination and crimping as described in Patent Document 2. Therefore, even if the occurrence of a step is suppressed to some extent, it is considered that the above-described variation in electrical characteristics occurs.

  The present invention has been made in view of the above problems and the background, and includes a ceramic green sheet and an internal electrode formed on the ceramic sheet, and a sheet with fewer steps in each layer (hereinafter, description is facilitated). Therefore, in the present specification, the sheet is generically referred to as a ceramic green sheet.) The object is to provide a forming method. By providing this method, it is intended to reduce the variation in electrical characteristics of ceramic multilayer electronic components, and to reduce or avoid the frequency of delamination during firing of the laminate.

  In order to solve the above-described problems, a method for manufacturing a ceramic green sheet according to the present invention is a method for manufacturing a ceramic green sheet using exposure and development processing, and is based on a base that can transmit light used for exposure processing. A step of adhering a photosensitive material containing powder having predetermined electrical characteristics on the surface thereof and capable of being exposed to light; and irradiating the photosensitive material with the light from the back surface of the base. And a step of performing an exposure process at an exposure amount at which the photosensitive material is exposed to a predetermined thickness from the base, and a step of developing the photosensitive material after the exposure process.

  In order to solve the above problems, a method for manufacturing a ceramic green sheet according to the present invention is a method for manufacturing a ceramic green sheet using exposure and development processing, and is a base that can transmit light used for exposure processing. In contrast, a first photosensitive material containing a powder having a predetermined electrical property and exposed to light is attached on the surface of the first photosensitive material from the back surface of the base. The first photosensitive material is exposed to light at an exposure amount at which the first photosensitive material is exposed to the first predetermined thickness from the base, and development processing is performed on the first photosensitive material after the exposure processing. A step of forming a light-shielding portion made of a member that does not transmit light used for the exposure processing on the surface of the first photosensitive material after the development processing, and the first photosensitive material and the light-shielding portion after the development processing Powder with predetermined electrical characteristics is contained on the surface of In addition, a second photosensitive material that can be exposed by light is attached, light is applied to the second photosensitive material from the back surface of the base, and the second photosensitive material is made of the first photosensitive material. And a step of performing an exposure process at an exposure amount at which a second predetermined thickness is exposed from the surface, and performing a development process on the second photosensitive material after the exposure process.

  In the above manufacturing method, before the step of attaching the photosensitive material to the base, a step of forming a light shielding portion made of a member that does not transmit light used for the exposure process on the surface of the base is performed. Is preferred. Further, it is preferable that the predetermined thickness at which the photosensitive material is exposed is substantially equal to the thickness of the light shielding portion.

  Further, in the above-described manufacturing method, the first photosensitive material is attached to the base, exposed to light, and developed, before performing the step of exposing and developing, from the member that does not transmit light used for the exposure process on the base surface. It is preferable that a step of forming another light shielding portion different from the light shielding portion is performed, and further, the first predetermined thickness at which the first photosensitive material is exposed is equal to the thickness of the other light shielding portion. It is preferable that they are substantially equal. Or it is preferable that the 2nd predetermined thickness by which the 2nd photosensitive material is exposed is substantially equal to the thickness of a light-shielding part.

  In order to solve the above-described problem, a method for manufacturing a ceramic green sheet according to the present invention is a method for manufacturing a ceramic green sheet using exposure and development processing, and includes a portion that can transmit light used for exposure processing. A step of forming a predetermined thickness of a light-shielding member that does not transmit light with respect to a predetermined region on the surface of the member having the sheet-formed surface as a surface; A process of adhering a photosensitive material containing powder having electrical characteristics and capable of being exposed to light, and irradiating the photosensitive material with light from the back surface of the member, exposing the photosensitive material to a predetermined thickness from the member. The method includes a step of performing an exposure process at a given exposure amount and a step of performing a development process on the photosensitive material after the exposure process.

  In order to solve the above problems, a method for manufacturing a ceramic green sheet according to the present invention is a method for manufacturing a ceramic green sheet using exposure and development processing, and is made of a material that does not transmit light used for exposure processing. Forming a predetermined pattern on the surface of the base capable of transmitting light, and attaching a photosensitive material containing powder having predetermined electrical characteristics on the base and the material and capable of being exposed to light; The photosensitive material is irradiated with light from the back surface of the table, the photosensitive material is exposed to a predetermined amount of exposure from the base, and the exposure processing is performed on the photosensitive material after the exposure processing. It includes the process of giving.

  In the above-described manufacturing method, the adhesion thickness of the photosensitive material is larger than the material thickness for forming the pattern, and the predetermined thickness of the photosensitive material exposed by the exposure process is equal to the thickness of the material for forming the pattern. It is preferable that they are substantially equal. Further, it is preferable that the adhesion thickness of the photosensitive material is substantially equal to the material thickness for forming the pattern, and the predetermined thickness of the photosensitive material exposed by the exposure process is substantially equal to the thickness of the material for forming the pattern.

  In order to solve the above-described problem, an electronic component manufacturing method according to the present invention is a multilayer ceramic electronic component manufacturing method, including a ceramic green sheet formed by the above-described ceramic green sheet manufacturing method. A plurality of ceramic green sheets are laminated, and the laminated ceramic green sheets are pressed in the thickness direction to form a laminated body.

  In order to solve the above-described problem, a method for manufacturing a ceramic green sheet according to the present invention is a method for manufacturing a ceramic green sheet using exposure and development processing, and includes a portion that can transmit light used for exposure processing. A step of attaching a photosensitive material containing a powder having predetermined electrical characteristics and capable of being exposed to light to the surface of the member having the sheet-formed surface as a surface; A step of irradiating the material with light and performing an exposure process at an exposure amount at which the photosensitive material is exposed to a predetermined thickness from the surface of the member; and a process of performing a development process on the photosensitive material after the exposure process. It is characterized by including.

  In the present invention, the photosensitive material formed on the surface of the member is exposed from the back surface of the light-transmitting member, whereby the exposed photosensitive material remaining on the member after the exposure and development processing (described later) It is characterized in that the thickness of the slurry solidifying part) can be accurately controlled. Therefore, it can be said that the manufacturing method including the step of exposing the photosensitive material on the surface of the member from the back surface of the member having the light transmissive portion is the manufacturing method according to the present invention. That is, as described in detail in the examples, before carrying out the process, various layers on the base, specifically, layers for obtaining a releasing action, ceramic layers, conductor patterns and ceramic parts Even when a layer or the like is formed, it is included in the present invention. Further, the case where a sheet in which a plurality of layers are laminated is formed by repeating the method of exposing and developing from the back of the member is also included in the present invention.

  Therefore, in the above manufacturing method, before the step of attaching the photosensitive material to the surface of the member, a step of forming a light shielding portion made of a material that cannot transmit light to a predetermined region of the surface of the member is performed. It is good to be. In this case, it is preferable that the predetermined thickness is substantially equal to the thickness of the light shielding portion. Furthermore, in the manufacturing method described above, the member may be subjected to a mold release treatment for facilitating the peeling of the ceramic green sheet from the surface.

  Further, in the above-described manufacturing method, the member may include a portion that is peeled and removed from the previous ceramic green sheet and a portion that forms a part of the ceramic green sheet. In this case, a part of the ceramic green sheet may be a layer made of a material different from the photosensitive material. Further, a part of the ceramic green sheet may be made of a material obtained by exposing a photosensitive material and a material that cannot transmit light.

  In addition, the above-described manufacturing method can be obtained after performing the step of forming a light-shielding portion on the surface of the member, the step of attaching the photosensitive material, the step of exposing the photosensitive material, and the step of developing the photosensitive material. A step of forming a further light-shielding portion on the outermost surface of the sheet, a step of attaching a further photosensitive material, a step of exposing the further photosensitive material from the back surface of the member, and a step of developing the further photosensitive material. It may be given. In this case, the material for forming the light shielding portion and the material for forming the further light shielding portion do not need to be the same, and the photosensitive material and the further photosensitive material need not be the same.

  In order to solve the above-mentioned problems, an electronic component manufacturing method according to the present invention is a multilayer ceramic electronic component manufacturing method, including a ceramic green sheet formed by the above-described ceramic green sheet manufacturing method. A plurality of ceramic green sheets are laminated, and the laminated ceramic green sheets are pressed in the thickness direction to form a laminated body. Since the ceramic green sheet obtained by the production method according to the present invention is superior to the sheet obtained by the conventional production method in terms of thickness accuracy, etc., in order to obtain high-quality electronic components, all sheets are included in the present invention. It is desirable to form by such a manufacturing method. However, according to the characteristics required for the electronic component, manufacturing the electronic component including the sheet obtained by the conventional manufacturing method can provide effects such as reduction in manufacturing cost.

  According to the present invention, it is possible to form a ceramic green sheet having a smaller step in each layer including the ceramic green sheet and the internal electrode formed thereon. By providing the method, it is possible to reduce variation in electrical characteristics of the ceramic multilayer electronic component and to reduce or avoid the frequency of delamination during firing of the laminate.

  In addition, when an electrode or a ceramic green sheet is formed by a conventional screen printing or coating coater or the like, irregularities are generated on the surface due to various effects such as the viscosity of the slurry described above. Usually, it is maintained in the exposure development processing. Furthermore, horns or scumming may occur during the application of slurry or the like, and it is conceivable that a short circuit or energization failure may occur when assembled as an electronic component. When the coating thickness is further reduced, there is a lower limit depending on various conditions such as the viscosity, and it becomes difficult to reduce the dimensional variation in the thickness direction.

  According to the present invention, the thickness of the layer is accurately controlled by the exposure dose as the distance from the surface of the substrate on which the layer is formed. Therefore, compared with the conventional method of forming a ceramic green sheet made of a material having desired electrical characteristics using a slurry containing powder having predetermined electrical characteristics by screen printing or coating coater, The sheet thickness controllability is remarkably improved, and it becomes possible to provide a sheet having a thin thickness which has been impossible until now and having excellent thickness uniformity. Therefore, it is possible to obtain an electronic component that is smaller and has excellent electrical characteristics while suppressing manufacturing variations.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a method for forming a ceramic green sheet single layer including an electrode portion in relation to a method for manufacturing an electronic component according to an embodiment of the present invention. In the figure, the cross section of the sheet in each process is shown, and the process proceeds according to the arrows. In the figure, for the substrate 1, for example, a PET film having an appropriate mold release treatment applied using a transparent silicon resin or the like is used. Further, for example, the electrode portion 3 is formed on the surface of the substrate 1 subjected to the release treatment in Step 1 by a method of screen printing a conductive paste conventionally used for electrode formation. The electrode portion is formed as a predetermined pattern having a predetermined thickness by a light shielding portion made of a material that does not transmit ultraviolet rays used in an exposure process described later.

  Generally, an electrode formed by screen printing has irregularities on the upper surface 3a of each electrode due to surface roughness or the like. Therefore, in step 2, the sheet in this state is pressurized from the upper surface 3a of the electrode to flatten the upper surface 3a and make the thickness of the electrode portion 3 uniform. Note that this step may be omitted if the flatness of the upper surface 3a and the thickness of each electrode portion 3 satisfy the desired conditions.

  In the subsequent step 3, a photosensitive slurry 4 for forming a ceramic layer is applied to the upper surfaces of the substrate 1 and the electrode part 3. The photosensitive slurry 4 is mainly formed from a mixture of a negative organic binder that becomes insoluble in a developer upon irradiation of ultraviolet rays, for example, and a ceramic powder having electrical characteristics such as a predetermined dielectric constant. Yes. That is, the photosensitive slurry contains a powder having predetermined electrical characteristics and is used as a photosensitive material that can be exposed to ultraviolet rays. The photosensitive slurry 4 is applied and formed not only on the upper surface of the substrate 1 on which the electrode portions 3 are not formed, but also on the upper surfaces of the individual electrode portions 3.

  The photosensitive slurry 4 is exposed by irradiating the photosensitive slurry 4 with ultraviolet rays from a surface (back surface) opposite to the surface on which the electrode portion 3 is formed in the substrate 1. The photosensitive slurry 4 becomes a slurry solidified portion 5 through the exposure process and the development process described later. In the exposure step, the electrode unit 3 acts as a mask for exposing the photosensitive slurry 4 to shield ultraviolet rays, and prevents exposure of the photosensitive slurry 4 existing on the upper surface of the electrode unit 3. That is, in the next development process, the photosensitive slurry present on the upper surface of the electrode portion 3 is melted and removed. In addition, the thickness of the photosensitive slurry 4 (slurry solidified portion 5) that remains insoluble during development is controlled by optimizing the amount of ultraviolet light at the time of exposure, that is, the light intensity, the exposure time, and the development conditions. It becomes possible to do.

By passing through the above process, it becomes possible to form the electrode 3 part and the slurry solidification part 5 having a certain thickness on the surface of the substrate 1. As will be described later, in this method it is possible to accurately control the thickness of the slurry coated portion 5, it can also be matched as needed exactly the thickness of the electrode part 3 the thickness It becomes. Thereafter, the layer including the slurry solidifying part 5 and the electrode part 3 is separated from the base 1 and used as a ceramic green sheet for manufacturing an electronic component.

  As described above, in the present invention, the electrode portion 3 to be an internal electrode is first formed on the surface of the substrate 1, the photosensitive slurry 4 is applied thereon, and then exposed from the back surface of the substrate 1. At that time, the thickness of the slurry solidifying portion 5 can be controlled with high accuracy by appropriately controlling the irradiation conditions of ultraviolet rays used for exposure and optimizing the developing conditions. Therefore, it is possible to form a ceramic green sheet having the same thickness as that of the internal electrode portion 3 and having a ceramic dielectric portion and an internal electrode having almost no interface gap in the thickness direction.

  In addition, the dispersion | variation in the film thickness of the slurry solidification part 5 which passed through the process of exposure in the above process and image development is influenced by the properties, such as a ceramic powder contained. However, a value of about ± 2 to 3% is obtained by optimizing the conditions of each process. Usually, the ceramic green sheet is formed by using a doctor blade, and the film thickness variation at that time is about ± 3 to 5%. That is, by using the present invention, a ceramic green sheet having a more uniform film thickness can be formed.

  An example of the relationship between the irradiation amount of ultraviolet rays and the film thickness of the ceramic green sheet obtained after exposure and development is shown in FIG. In the figure, the horizontal axis represents the exposure amount per unit area of ultraviolet light having a wavelength of 405 nm, and the vertical axis represents the sheet thickness after development. As the photosensitive slurry, a mixture of barium titanate powder having a diameter of about 0.2 μm and a negative binder at a volume ratio of 1/1 is used. After this is formed on a substrate surface (not shown) to a thickness of about 8 μm, an exposure process or the like is performed from the back surface of the substrate. The illuminance of ultraviolet rays at the time of exposure is 50 mw per unit area, and the exposure amount is changed depending on the irradiation time.

  In the development, the sample was immersed for 30 seconds in a developer composed of a 1% by weight aqueous sodium carbonate solution maintained at 30 ° C., and then the sample was immersed for 90 seconds in pure water maintained at 30 ° C. As shown in the figure, a clear correlation is obtained between the exposure amount and the obtained sheet thickness. Further, as indicated by error bars in the figure, a value of ± 0.5 to 2.0% is obtained as a substantially constant thickness variation. As described above, it is possible to control the exposure thickness, that is, the sheet thickness, by changing the exposure amount of the photosensitive slurry containing the powder having the predetermined electric characteristics. Was confirmed. The present invention has been made based on this confirmed matter.

  In consideration of the matters described above, as a first application example of the present invention, a method for forming a ceramic green sheet composed only of a ceramic dielectric layer will be described below with reference to FIGS. 3A and 3B. It should be noted that the same reference numerals are attached to the same components as those in the embodiment shown in FIG. 3A and 3B show a cross section of the substrate 1 and the like and the slurry solidified portion 5 and the like regarding the step of forming the slurry solidified portion 5 having a predetermined thickness on the surface of the substrate 1.

  In step 11, the photosensitive slurry 4 is applied on the surface of the substrate 1 that has been subjected to the mold release treatment with a thickness greater than or equal to a predetermined thickness. In that case, the coating method is not particularly limited. In subsequent step 12, ultraviolet light is irradiated from the back surface of the substrate 1 to perform exposure processing up to a predetermined thickness of the photosensitive slurry 4. Furthermore, by optimizing the development processing, the photosensitive slurry 4 that becomes a portion having a predetermined thickness or more is melted and removed. After passing through the above steps, by removing the base 1, it becomes possible to obtain a ceramic green sheet with a small variation in film thickness (step 3).

  Usually, when an attempt is made to obtain a ceramic green sheet only by directly applying the slurry on the substrate, the thickness at which the slurry can be applied substantially uniformly on the substrate is limited by various conditions such as the viscosity of the slurry. For this reason, it has heretofore been difficult to obtain a ceramic green sheet having a thickness of a certain value or less. According to the present invention, the slurry is applied with a thickness that is easy to apply, and the sheet thickness is controlled in the subsequent exposure process. As described above, in this exposure process, it is possible to control the exposure thickness (the thickness of the ceramic green sheet remaining after the development process) regardless of the coating thickness. It becomes possible to control the thickness at a value below the lower limit.

  As described above, the surface of the substrate 1 has been subjected to a mold release process in advance. However, from the viewpoint of cost and the like, for example, a material that is difficult to perform a so-called mold release process may be used as the substrate 1. In this case, for example, as shown in FIG. 3B, a light-transmitting release layer (a layer indicated by reference numeral 2 in the figure) is previously applied to the surface of the substrate 1 that has not been subjected to any surface treatment in step 10. It is good also as forming and forming the layer which consists of the photosensitive slurry 4 on this. Further, as the layer 2, a layer having a so-called blur preventing function for preventing bleeding of the forming portion edge (end portion) at the time of forming the light shielding portion or the like may be formed. In this case, the layer 2 is finally peeled off and removed from the slurry solidifying portion 5 together with the substrate 1. That is, the base body 1 and the layer 2 function as a member having a part that transmits light as a whole.

  In addition, when an electronic component or the like is formed by laminating ceramic green sheets, for example, a sheet corresponding to the lowermost layer of the electronic component may be required to have characteristics different from predetermined electrical characteristics. In this case, it is preferable to form a sheet in which a plurality of layers corresponding to each required characteristic are laminated. The method shown in FIG. 3C corresponds to such a case.

  Specifically, the release layer 2 is formed on the substrate 1 (step 10), and the light-transmitting ceramic layer 6 is formed thereon (step 10 '). The ceramic layer 6 is formed for a purpose different from that of the slurry solidifying portion 5 formed in a later step. In this case, it may be considered that the ceramic layer 6 does not require the film thickness uniformity required at the time of forming the slurry solidified portion 5. That is, the ceramic layer 6 may be formed from the steps 10 to 12 in FIG. 3A or may be formed by a conventional coating method. In this case, the substrate 1 and the layer 2 are separated from the ceramic green sheet by a peeling operation, and the ceramic layer 6 forms a part of the ceramic green sheet.

  In the present invention, exposure of the photosensitive slurry adhering to the upper surface of the electrode is reliably prevented, and the slurry on the electrode surface can be surely removed through the development process. The second application example of the present invention described below pays attention to the effect. Specifically, there may be a case where the electrode portion and the ceramic green sheet in which the electrode portion is present are relatively thick, and for example, the allowable range of the electrical characteristics can be sufficiently satisfied by the conventional photosensitive slurry coating technique. Hereinafter, a second application example of the present invention will be described with reference to FIG.

  First, in step 2, the electrode part 3 is formed on the surface of the base 1 on which the mold release process has been performed. At that time, step 1 described in the embodiment of the present invention may be performed. Subsequently, a photosensitive slurry 4 for forming a ceramic layer is applied to the upper surfaces of the substrate 1 and the electrode unit 3. The photosensitive slurry 4 is applied on the base 1 by a thickness substantially equal to the thickness of the electrode portion 3 by a conventional application method. At this time, the slurry 4 is applied and formed not only on the upper surface of the substrate 1 on which the electrode portions 3 are not formed, but also on the upper surfaces of the individual electrode portions 3 (step 3 ').

  The photosensitive slurry 4 is irradiated with ultraviolet rays from the surface (back surface) opposite to the surface on which the electrode portion 3 is formed in the substrate 1 to expose the photosensitive slurry 4 over the entire film thickness and development described later. Through this process, the photosensitive slurry 4 becomes a slurry solidifying portion 5. In the exposure step, the electrode unit 3 acts as a mask for exposing the photosensitive slurry 4 to shield ultraviolet rays, and reliably prevents exposure of the photosensitive slurry 4 existing on the upper surface of the electrode unit 3. Therefore, the upper surface 3a of the electrode part 3 is exposed by the development process, and a good connection can be easily obtained, for example, when connecting another electrode to this.

  Furthermore, as a third application example of the present invention, a method of forming an electrode pattern and a so-called post for connecting the electrode pattern with a further electrode in another ceramic green sheet or the like in a ceramic green sheet. As shown in FIG. In the figure, in step 21, an electrode portion 3 to be a post is formed on the surface of the base 1 that has been subjected to the release treatment. The electrode unit 3 acts as a light shielding member in the exposure process. Further, the application of the photosensitive slurry 4 as the first photosensitive material, the exposure treatment of the first predetermined thickness with respect to the photosensitive slurry 4 from the back surface of the base 1, and the melting and removal of excess photosensitive slurry by the development processing. To form a sheet composed of the base 1, the post electrode 3 and the slurry solidifying portion 5 shown in Step 22.

  In step 23, the pattern electrode 7 serving as an internal electrode is formed on the upper surface of the sheet shown in step 2. The pattern electrode 7 functions as a light shielding member in the exposure process. Further, the photosensitive slurry 4 as the second photosensitive material is applied again on the upper surface of the pattern 7 electrode or the like. In the present embodiment, the first photosensitive material and the second photosensitive material are the same, but these may be different materials depending on the desired electrical characteristics. After the application, a second predetermined thickness exposure process is performed on the photosensitive slurry 4 applied again from the back surface of the base 1, and a developing process is performed to melt and remove excess portions of the photosensitive slurry 4 applied again. A sheet composed of the base 1, the post electrode 3, the pattern electrode 7, and the slurry solidifying portion 5 is formed in Step 24.

  Thereafter, by removing the base 1 from the sheet, a ceramic green sheet having internal pattern electrodes and posts can be obtained (step 25). In the implementation of this example, it is preferable to select materials in advance so that the slurry solidifying portion can transmit light for exposure when preparing the photosensitive slurry, and use these materials. In the present embodiment, a modification is included including the step of forming two layers. However, it is also possible to grasp the lower layer as a member having a portion that transmits light for exposure, that is, as a modification of the base. Thus, the present modification can be described as a simple repetition of the embodiment of the present invention.

  Further, for example, when forming a post, it may be necessary to form an electrode having a thickness that cannot be formed by a normal screen printing method for the sake of circuit design. The present invention is also applicable to such a case. Hereinafter, as a fourth application example of the present invention, a method of forming a thicker electrode will be described below with reference to FIG. In the figure, in step 31, an electrode portion 3 to be a post is formed on the surface of the base 1 that has been subjected to the release treatment. In the subsequent step 32, application of the photosensitive slurry 4 and exposure processing from the back surface of the base 1 are performed. At this time, the exposure amount is adjusted so that the photosensitive slurry 4 is exposed to a predetermined thickness regardless of the thickness of the electrode portion 3.

  After the exposure is completed, the excess photosensitive slurry 4 is melted and removed by development processing to form a sheet including the base 1, the post electrode 3, and the slurry solidifying portion 5 shown in Step 33. Since the electrode part 3 acts as a mask, the photosensitive slurry 4 on the upper surface 3a is not exposed, and the photosensitive slurry 4 is removed by development processing. That is, a through pattern 9 corresponding to the internal electrode portion 3 is formed on the slurry solidifying portion 5 having a predetermined thickness in a self-aligning manner.

  In step 34, the upper surface of the electrode part 3, that is, the penetrating pattern 9, is filled with, for example, a conductive paste, and the additional electrode part 11 is formed. Thereby, an internal electrode having the same upper surface as the upper surface of the slurry solidifying part 5 is formed. By performing the above steps, the electrode portions can be stacked with high accuracy, and a thick internal electrode portion that is usually difficult to form can be obtained by a relatively simple process.

  As described above, by implementing the present invention, it is possible to form a ceramic green sheet having a uniform film thickness in which an internal electrode and a dielectric layer, that is, an insulating layer having a predetermined specification are mixed. In practice, these ceramic green sheets are used as materials for forming electronic components such as multilayer ceramic capacitors and multilayer ceramic inductors. Examples of a method for forming a multilayer ceramic capacitor and a multilayer ceramic inductor will be described below. Note that in the drawings shown below, components having the same contents as the above-described components or steps are described with the same reference numerals or steps.

  FIG. 7 shows a main part of a method for forming a multilayer ceramic capacitor. First, in step 2, an electrode portion 3 having a predetermined thickness is formed on the substrate 1. In addition, the product in this method is a capacitor | condenser, and the electrode part 3 is used as an electrode in a capacitor | condenser. Therefore, although not clearly shown in the drawing showing the cross section, the electrode portion 3 is formed in a flat plate shape. Subsequently, through the processes shown in Steps 3 and 4, the electrode part 3 and the dielectric part (slurry solidifying part 5) having a predetermined thickness are formed on the substrate 1.

  In this method, in step 4 ′, a dielectric portion 6 having a predetermined thickness is further formed on the upper surfaces of these electrode portions 3 and the like. Thereafter, in step 5 ', the substrate 1 is removed from these electrode portions 3 and the like to obtain a ceramic green sheet for a capacitor. The ceramic green sheets obtained by the above-described method are laminated and further pressed in the thickness direction to improve the adhesion between the sheets. A multilayer ceramic capacitor is obtained by firing the multilayer ceramic green sheet after pressurization and forming terminal electrodes and the like outside thereof.

  In this method, from the viewpoint of reducing man-hours, the dielectric portion 6 is directly formed on the electrode portion 3 and the like in step 4 '. As the formation method, various methods such as a printing method and a doctor blade method can be applied. However, there may be a case where a higher uniformity of the dielectric portion 6 is required. In such a case, as shown in FIG. 8, the slurry solidification part 5 according to the first application example is formed in advance, and the sheet 5, the ceramic green sheet composed of the electrode part 3 and the dielectric part (5), Is preferably used. By laminating these sheets and passing through the pressurization and firing steps (steps 6 to 8), it is possible to obtain a multilayer ceramic capacitor with less variation in electrical characteristics than the above-described method.

  Furthermore, as shown in FIG. 9, the slurry solidification part 5 according to the first application example of the present invention is formed in advance on the base 1 (steps 11 ′ and 12 ′), and the base 1 and the slurry solidification part 5 are newly added. It is good also as forming the part which consists of the electrode part 3 and the dielectric material part (5) on it as a simple base (step 2'-4 '). In this case, since the slurry solidifying unit 5 needs to sufficiently transmit ultraviolet rays or the like used for the exposure process, there is a possibility that a material restriction with the photosensitive slurry may occur. However, as in the case shown in FIG. 8, it is possible to easily control the thickness of each sheet, and it is possible to obtain a multilayer ceramic capacitor with less variation in electrical characteristics.

  In this method, the thickness of the slurry solidified portion 5 formed on the substrate 1 is controlled by performing an exposure process from the back surface of the substrate 1. However, for example, a sheet obtained by the method may be used for the outermost layer of the multilayer capacitor, or the sheet may be used only for a wiring portion, not for capacitor formation. In this case, the thickness accuracy of the slurry solidifying part 5 is not so required. Therefore, from the viewpoint of simplifying the process, the layer is subjected to strict thickness control by performing exposure processing from the surface used conventionally. It is also possible not to perform.

  FIG. 10 shows a main part of a method for forming a multilayer ceramic inductor. First, in steps 2A and 2B, an electrode portion 3A or 3B having a predetermined thickness is formed on the substrate 1. The product in this method is an inductor, and the electrode portions 3A and 3B are used as an inductor body. Therefore, although not shown in this drawing showing a cross section, the electrode portion 3A is formed in a frame shape with a part cut away when viewed from the upper surface. Moreover, the electrode part 3B is used as a post electrode for connecting the electrode part 3A formed in the ceramic green sheet laminated above and below the ceramic green sheet including the electrode part 3B, and is formed in a column shape. By sequentially stacking these electrode portions 3A and 3B, an inductor body is formed. Subsequently, the photosensitive slurry 4 is applied onto the substrate 1 and the electrode portion 3A or 3B through the steps shown in Steps 3A and 3B, respectively.

  Each of these sheets is exposed from the back surface of the substrate 1 and further developed to form an electrode portion 3 and an insulator portion or magnetic body portion (5) having a predetermined thickness on the substrate 1. (Steps 4A and 4B). The ceramic green sheets (steps 5A and 5B) obtained by removing the substrate 1 from these sheets are sequentially laminated (step 6). After the laminated ceramic green sheets are pressed from the thickness direction (step 7) and fired (step 8), terminal electrodes and the like are formed outside thereof to obtain a laminated ceramic inductor.

  Note that, when an inductor is formed by the method shown in FIG. 10, the number of stacked layers may be increased in order to obtain an inductor having desired characteristics. In this case, the connection part of the electrode part between each layer increases, and connection reliability etc. may fall. In addition, it may be difficult to align the electrode portion 3A and the electrode portion 3B at the time of stacking, such as when the width (thickness in the paper direction shown in the drawing) of the electrode portion 3A as the inductor body becomes narrower. . 11A and 11B show an inductor manufacturing method for dealing with such a case. Specifically, the third application example shown in FIG. 5 is applied.

  In the method shown in FIG. 11A, in order to form an inductor, the post electrode portion 3 in FIG. 5 becomes the post electrode portion 3B, and the pattern electrode portion 7 becomes the frame-shaped pattern electrode portion 3A. A ceramic green sheet including the post electrode portion 3B and the pattern electrode portion 3A bonded to the post electrode portion 3B shown in step 25 is obtained according to the process shown in the second application example. As shown in Steps 6 to 8, the sheets are alternately laminated, pressed, fired, and then formed with terminal electrodes and the like, thereby obtaining a multilayer ceramic inductor with better lamination accuracy. By forming the inductor by this method, the number of stacked layers is reduced, and the number of connection portions of the electrode portions between the layers is also reduced. As a result, the stacking accuracy can be easily improved, and the connection reliability can be improved.

  In the case of forming a multilayer ceramic inductor, when the sheet obtained by the method is used at the end of the inductor, the thickness accuracy of the post electrode 3A in FIG. 11A may not be required so much. In this case, from the viewpoint of simplification of the process or reduction of processing costs, a layer including the post electrode 3A may be formed by a conventional technique as shown in FIG. 11B. Specifically, the slurry solidified portion 5 is formed on the substrate 1 by a conventional method (step 20 ′), and a through hole 3B ′ is formed by mechanical punching, laser processing, or the like (step 21 ′). The layer is formed by filling the hole 3B ′ with an electrode material. Alternatively, as shown in step 20, after forming a predetermined thickness of the photosensitive slurry 4 on the substrate 1, the through holes 3B 'may be formed by normal exposure, patterning processing, or the like.

As described above, according to the present invention, it is possible to form a ceramic green sheet including an internal electrode having excellent thickness uniformity. Since the ceramic green sheet according to the present invention is excellent in flatness, the pressing pressure in the step of pressing after lamination can be made 100 kg / cm ² or less. The numerical value varies depending on the arrangement of the electrodes in the sheet, the material or viscosity of the photosensitive slurry, and the like, but can be reduced to 50 kg / cm ² or less depending on conditions. Therefore, deformation at the time of pressurization can be suppressed small, and desired electrical characteristics can be obtained with high accuracy. In addition, it is possible to greatly reduce the frequency of deformation such as delamination during firing due to the pressure treatment. In addition, since the pressing pressure is significantly reduced, the manufacturing equipment can be simplified, and the manufacturing cost can be greatly reduced.

  Specific examples of the metal material used when forming the internal electrode include Ag, Ni, AgPd, Pd, Cu, and the like, and examples of the organic binder include ethyl cellulose. Alternatively, it is desirable that the material is appropriately selected from various materials depending on the method of forming the electrode portion. Further, although the screen printing method has been described as an example of the method for forming the electrode portion, it may be formed by so-called photo processing for performing exposure and development processing. According to the method, it is possible to control the shape, formation position, and the like of the electrode portion with higher accuracy.

  A method for forming an electrode portion by photolithography will be briefly described here with reference to FIGS. Both figures schematically show a state in which the base 1 and the electrode part 3 are viewed from the cross section, and the process proceeds according to the arrows in the figures. In FIG. 12, first, in step 1, for example, an ultraviolet-sensitive electrode portion 13 made of conductive metal powder and an organic binder is formed on the base 1 in order to form an electrode portion. Subsequently, in step 2, the pattern of the electrode unit 3 is exposed by irradiating ultraviolet rays through the photomask 15. By developing this, the electrode portion 3 can be formed with high accuracy. By performing the above steps, it is possible to control the shape, formation position, and the like of the electrode portion with higher accuracy. In addition, regarding the cross-sectional shape of the electrode, not only a vertical side surface is simply formed, but also taper processing can be easily performed. Therefore, by adjusting these, the integration between the electrode and the slurry solidified portion is expected to be improved. .

  For example, the case where the formation region of the electrode part 3 is smaller than the surface area of the base 1 can be considered. In this case, as shown in FIG. 13, it is preferable to limit the formation part of the photosensitive electrode part 13 to some extent by using screen printing or the like in advance. Thus, by forming the photosensitive electrode portion 13 only in the vicinity of the position where the electrode portion 3 is formed, it is possible to reduce the amount of photosensitive electrode material, developer, and the like, and to reduce the cost of the process. It becomes. Moreover, since the photosensitive electrode material which should be removed by development reduces, the effect of shortening the time which development requires can also be acquired.

  Further, as the material for forming the photosensitive slurry, an organic binder exhibiting negative characteristics and a dielectric material, particularly barium titanate have been described here, but the present invention is not limited to these materials. The organic binder is desirably determined as appropriate in consideration of various characteristics such as exposure characteristics, viscosity, and peelability. Furthermore, the present invention can be applied not only to capacitors and inductors but also to various laminated ceramic electronic components such as resistors, varistors, thermistors, and piezoelectric elements. Therefore, various materials such as dielectric materials, glass-based materials, ferrite-based materials, and other ceramic materials including metal oxides that have desired electrical characteristics and the like are also applicable to the powder material applied to the present invention. Can be used.

  Further, although ultraviolet rays are used for the exposure, it is desirable to appropriately change the exposure light appropriately according to the characteristics of the organic binder used, that is, the characteristics of the photosensitive material. In the present invention, the electrode portion is used as a mask during the exposure process. However, the present invention is not limited to this, and any material that does not transmit light used for the exposure process can be used as well as the electrode material. It is preferable to use various materials such as materials according to desired electrical characteristics and the like. In addition, photosensitive slurry is used to form a layer made of a dielectric material, but various methods can be used as long as a photosensitive material is attached to and formed on the base, such as attaching a photosensitive sheet to the base. These methods are applicable.

  In addition, although examples of manufacturing methods of a multilayer ceramic capacitor or a multilayer ceramic inductor are shown, the present invention is not limited to application to the example. A layer obtained by carrying out the present invention may be used as a part of the plurality of layers. By using the ceramic green sheet obtained according to the present invention in a timely manner to form a multilayer electronic component, it is possible to easily provide an electronic component with more excellent electrical characteristics than when using a sheet according to the prior art. It becomes possible to do.

It is a flowchart which shows the formation method of the ceramic green sheet which concerns on embodiment of this invention. It is a figure which shows the relationship between an exposure amount and the residual film thickness of the photosensitive slurry after image development. It is a flowchart which shows the formation method of the ceramic green sheet which is a 1st application example about embodiment of this invention. It is a flowchart which shows the formation method of the ceramic green sheet which is a 1st application example about embodiment of this invention. It is a flowchart which shows the formation method of the ceramic green sheet which is a 1st application example about embodiment of this invention. It is a flowchart which shows the formation method of the ceramic green sheet which is a 2nd application example about embodiment of this invention. It is a flowchart which shows the formation method of the ceramic green sheet which is a 3rd application example about embodiment of this invention. It is a flowchart which shows the formation method of the ceramic green sheet which is a 4th application example about embodiment of this invention. It is a flowchart which shows the principal part about the formation method of the multilayer ceramic capacitor using this invention. It is a flowchart which shows the principal part about the formation method of the multilayer ceramic capacitor using this invention. It is a flowchart which shows the principal part about the formation method of the multilayer ceramic capacitor using this invention. It is a flowchart which shows the principal part about the formation method of the multilayer ceramic inductor using this invention. It is a flowchart which shows the principal part about the formation method of the multilayer ceramic inductor using this invention. It is a flowchart which shows the principal part about the formation method of the multilayer ceramic inductor using this invention. It is a figure which shows an example of the formation method of the electrode part on a base. It is a figure which shows an example of the formation method of the electrode part on a base.

Explanation of symbols

1: Substrate 3: Electrode unit 4: Photosensitive slurry 5: Slurry solidification unit 6: Ceramic layer 7: Pattern electrode 9: Penetration pattern 11: Additional electrode unit 13: Photosensitive electrode unit 15: Photomask

Claims (7)

A method for producing a ceramic green sheet using exposure and development,
A layer made of a material capable of transmitting light used for the exposure process and having a predetermined pattern space is formed on the surface of the member capable of transmitting the light,
Filling the predetermined pattern space using a material that does not transmit light and forming a light-shielding portion having a first predetermined thickness on the basis of the surface of the layer,
Including a powder having predetermined electrical characteristics on the layer and the light-shielding portion, and attaching a photosensitive material that can be exposed by the light;
The light is applied to the photosensitive material from the back surface of the member, and the exposure processing is performed at an exposure amount at which the photosensitive material is exposed to a second predetermined thickness with respect to the surface of the layer. ,
A method for producing a ceramic green sheet, comprising a step of performing the development process on the photosensitive material after the exposure process.   The method for producing a ceramic green sheet according to claim 1, wherein the first predetermined thickness and the second predetermined thickness are substantially equal. The method for forming a ceramic green sheet according to claim 1, wherein the member includes a release layer made of a material capable of transmitting the light and a base capable of transmitting the light. The method for forming a ceramic green sheet according to claim 1 , wherein the light shielding portion is an electrode portion made of a conductive material . 5. The method of forming a ceramic green sheet according to claim 4, wherein the electrode portion is formed by photolithography that includes exposure and development processing. The method for forming a ceramic green sheet according to claim 5, wherein a side surface in the cross-sectional shape of the electrode portion is tapered. A method for producing a multilayer ceramic electronic component comprising:
A plurality of ceramic green sheets including a ceramic green sheet formed by the method of manufacturing a ceramic green sheet according to any one of claims 1 to 6, are laminated,
A method for manufacturing a ceramic electronic component, comprising pressing the laminated ceramic green sheets in the thickness direction to form a laminated body.

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