Manufacturing methods for electronic components

Abstract

To provide a method for manufacturing electronic components that ensures stable quality. [Solution] A method for manufacturing an electronic component having external electrodes provided on a first end face and a second end face, comprising the steps of: moving a base body 110 downward so that the base body is immersed in a conductive paste layer 51 which is a precursor of the external electrodes from the first end face side; and after the base body has been immersed in the conductive paste layer from the first end face side, moving the base body upward so that it is pulled out of the conductive paste layer. In at least one of the steps of immersing the base body in the conductive paste layer from the first end face side and pulling the base body out of the conductive paste layer, the base body is moved up and down along a virtual helical trajectory ST. Viewed from the vertical, the virtual helical trajectory ST includes a portion in which the radius of the virtual helical trajectory ST decreases as it moves from top to bottom.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an electronic component.

Background Art

[0002] Conventionally, an electronic component including a substantially rectangular parallelepiped body portion in which a plurality of dielectric layers and internal electrode layers are alternately laminated, and external electrodes is known. The external electrodes are provided on a pair of end faces in the length direction of the body portion and on a part of each of the four side faces connecting the pair of end faces to each other. Japanese Patent Application Laid-Open No. 2006-319272 (Patent Document 1) discloses a method for manufacturing a multilayer ceramic capacitor as an example of such an electronic component.

[0003] [[ID=1--6]]In the method for manufacturing an electronic component disclosed in Patent Document 1, the body portion is immersed from the end face side in a conductive paste layer that is a precursor of the external electrode, and then pulled up from the conductive paste layer after the immersion. Thereby, an external electrode is formed on the end face of the body portion.

Prior Art Documents

Patent Documents

[0004] [[ID=2--6]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] From the viewpoint of stabilizing the quality of the electronic component, it is important to suppress the occurrence of so-called bubble entrainment in which bubbles are entrapped in the gap between the body portion and the external electrode when the external electrode is formed on the body portion. This is because if bubble entrainment occurs, there is a possibility that the electronic component may not have the desired performance.

[0006] From the perspective of stabilizing the quality of electronic components, it is also important to ensure sufficient thickness of the external electrodes and to reduce individual differences in the shape of the external electrodes. In particular, the shape of the edges of the external electrodes formed on the side of the base body is especially prone to individual differences because it depends on the degree to which the conductive paste constituting the conductive paste layer wets the side.

[0007] Therefore, this disclosure has been made to solve the above-mentioned problems and aims to provide a method for manufacturing electronic components with stable quality. [Means for solving the problem]

[0008] A method for manufacturing an electronic component according to the present disclosure is a method for manufacturing an electronic component comprising a base body having a first end face and a second end face opposite to each other in the longitudinal direction, and four sides connecting the first end face and the second end face, and external electrodes provided on each of the first end face and the second end face. The method for manufacturing an electronic component according to the present disclosure comprises the steps of: moving the base body downward so that the base body is immersed in a conductive paste layer which is a precursor of the external electrodes from the first end face side; and after the base body has been immersed in the conductive paste layer from the first end face side, moving the base body upward so that the base body is pulled up from the conductive paste layer. In at least one of the steps of immersing the base body in the conductive paste layer from the first end face side and pulling the base body up from the conductive paste layer, the base body is moved up and down along a virtual helical trajectory. When viewed from the vertical, the virtual spiral trajectory includes a portion where the radius of the virtual spiral trajectory decreases as it moves from top to bottom.

[0009] In the method for manufacturing an electronic component according to the above disclosure, the base body includes a ridge portion which is the portion where each of the four sides intersects with the first end face, and a rounded corner portion on the first end face side of each of the four sides. In this case, in the step of immersing the base body in the conductive paste layer from the first end face side, the base body is moved downward along the virtual helical trajectory, and the radius of the virtual helical trajectory is maintained until the ridge portion and the corner portion are immersed in the conductive paste layer, and from the time the ridge portion and the corner portion are immersed in the conductive paste layer, the radius of the virtual helical trajectory decreases as it moves from top to bottom.

[0010] In the method for manufacturing an electronic component based on the above disclosure, in the step of pulling up the base body from the conductive paste layer, the base body is moved upward along the virtual helical trajectory, the radius of the virtual helical trajectory increases as it moves from bottom to top, and the radius of the virtual helical trajectory is maximized when the first end face reaches the surface of the conductive paste layer. [Effects of the Invention]

[0011] According to this disclosure, it is possible to provide a method for manufacturing electronic components with stabilized quality. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic perspective view showing the appearance of a multilayer ceramic capacitor manufactured according to the manufacturing method for multilayer ceramic capacitors according to the embodiment. [Figure 2] Figure 1 is a schematic cross-sectional view of a multilayer ceramic capacitor. [Figure 3] Figure 1 is a schematic cross-sectional view of a multilayer ceramic capacitor. [Figure 4] This is a flowchart showing the manufacturing method of a multilayer ceramic capacitor according to an embodiment. [Figure 5] Figure 4 is a detailed flow chart of step S8 in the manufacturing flow shown. [Figure 6] It is a schematic front view for explaining steps S811 and S812 of the manufacturing flow shown in FIG. 5. [Figure 7] It is a schematic front view for explaining step S812 of the manufacturing flow shown in FIG. 5. [Figure 8] It is a schematic enlarged front view for explaining the movement of the base body in step S812 of the manufacturing flow shown in FIG. 5. [Figure 9] It is a schematic plan view for explaining the movement of the base body in step S812 of the manufacturing flow shown in FIG. 5. [Figure 10] It is a schematic plan view for explaining the movement of the base body in step S812 of the manufacturing flow shown in FIG. 5. [Figure 11] It is a schematic front view for explaining step S813 of the manufacturing flow shown in FIG. 5. [Figure 12] It is a schematic enlarged front view for explaining the movement of the base body in step S813 of the manufacturing flow shown in FIG. 5. [Figure 13] It is a schematic plan view for explaining the movement of the base body in step S813 of the manufacturing flow shown in FIG. 5. [Figure 14] It is a schematic plan view for explaining the movement of the base body in step S813 of the manufacturing flow shown in FIG. 5. [Figure 15] It is a schematic front view for explaining step S813 of the manufacturing flow shown in FIG. 5. [Figure 16] It is a schematic front view for explaining step S813 of the manufacturing flow shown in FIG. 5 in the manufacturing method of the multilayer ceramic capacitor according to the second modification.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments shown below exemplify a manufacturing method of a multilayer ceramic capacitor as a manufacturing method of an electronic component. Note that the manufacturing method of the electronic component according to the present embodiment shown below is also applicable to manufacturing methods of multilayer ceramic inductors, multilayer ceramic thermistors, and the like.

[0014] In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and their descriptions will not be repeated. In the drawings, the length direction of the element body is denoted by L, the width direction of the element body is denoted by W, and the stacking direction of the element body is denoted by T. The element body will be described in detail later.

[0015] (Embodiment) <A. Configuration of Multilayer Ceramic Capacitor> FIG. 1 is a perspective view schematically showing the appearance of a multilayer ceramic capacitor manufactured according to the manufacturing method of a multilayer ceramic capacitor according to an embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II of the multilayer ceramic capacitor shown in FIG. 1. FIG. 3 is a schematic cross-sectional view taken along line III-III of the multilayer ceramic capacitor shown in FIG. 1. First, referring to FIGS. 1 to 3, the configuration of a multilayer ceramic capacitor 100 manufactured according to the manufacturing method of a multilayer ceramic capacitor according to the present embodiment will be described.

[0016] As shown in FIGS. 1 to 3, the multilayer ceramic capacitor 100 according to the present embodiment includes an element body 110 and external electrodes.

[0017] The element body 110 has a substantially rectangular parallelepiped shape. The element body 110 has a first side surface 111 and a second side surface 112 that face each other in the stacking direction T, a third side surface 113 and a fourth side surface 114 that face each other in the width direction W orthogonal to the stacking direction T, and a first end surface 115 and a second end surface 116 that face each other in the length direction L orthogonal to the stacking direction T and the width direction W. These four side surfaces (that is, the first side surface 111, the second side surface 112, the third side surface 113, and the fourth side surface 114) connect the first end surface 115 and the second end surface 116 to each other. <00001​The base body 110 includes multiple corners 110a (see Figure 6). The multiple corners 110a are the rounded portions on the first end face 115 side of each of the four sides, and the rounded portions on the second end face 116 side of each of the four sides. In other words, the multiple corners 110a are formed by the rounded portions where three adjacent faces from the first side 111, second side 112, third side 113, fourth side 114, first end face 115, and second end face 116 intersect.

[0019] The base body 110 includes multiple ridge sections 110b (see Figure 6). The multiple ridge sections 110b are formed at the points where the first end face 115 intersects with each of the four sides, and at the points where the second end face 116 intersects with each of the four sides. All of the multiple ridge sections 110b are rounded.

[0020] The base body 110 includes multiple side ridge sections 110c (see Figure 6). Each of the multiple side ridge sections 110c is formed at the intersection of two adjacent faces among the four sides. All of the multiple side ridge sections 110c are rounded.

[0021] The dimensions of the base body 110 are, for example, 0.1 mm to 3.2 mm in the length direction L, 0.05 mm to 1.6 mm in the width direction W, and 0.05 mm to 1.6 mm in the stacking direction T. Tolerances are also taken into account in addition to the above dimensions.

[0022] The external electrode consists of a first external electrode 120 and a second external electrode 130. The first external electrode 120 is provided on the first end face 115. The second external electrode 130 is provided on the second end face 116.

[0023] The first external electrode 120 includes an end-face side first external electrode 121 and a side-side first external electrode 122. The end-face side first external electrode 121 is a portion provided across the entire first end face 115. The side-side first external electrode 122 is a portion extending from the first end face 115 to the first side surface 111, the second side surface 112, the third side surface 113, and the fourth side surface 114, respectively.

[0024] The second external electrode 130 includes an end-face side second external electrode 131 and a side-side second external electrode 132. The end-face side second external electrode 131 is a portion provided across the entire second end face 116. The side-side second external electrode 132 is a portion extending from the second end face 116 to the first side 111, the second side 112, the third side 113, and the fourth side 114, respectively.

[0025] The first external electrode 120 and the second external electrode 130 include a base electrode layer 160 and a plating layer 170. The plating layer 170 covers the base electrode layer 160.

[0026] The base electrode layer 160 includes at least one of a baked layer, a resin layer, and a thin film layer. In this embodiment, the base electrode layer 160 is composed of a baked layer.

[0027] The baked layer contains, for example, a metal component and a glass component. The metal component consists of one metal component selected from the group consisting of Ni, Cu, Ag, Pd, and Au, or an alloy containing this metal; for example, an alloy of Ag and Pd can be used. The glass component contains at least one of Si and Zn.

[0028] The baked layer may consist of a single layer or multiple stacked layers. The baked layer may be a layer baked after the conductive paste 53 is applied to the base part 110, or a layer fired simultaneously with the internal electrode layer 118. If the baked layer is a layer baked after the conductive paste 53 is applied to the base part 110, it is preferable that the baked layer contains a glass component. If the baked layer is a layer fired simultaneously with the internal electrode layer 118, it is preferable that the baked layer contains a dielectric. The conductive paste 53 and the internal electrode layer 118 will be described later.

[0029] The plating layer 170 is placed on the under electrode layer 160. The material constituting the plating layer 170 can be one metal selected from the group consisting of Ni, Cu, Ag, Pd, Au, and Sn, or an alloy containing this metal. As an example, the plating layer 170 can be made up of a layer of Ni and a layer of Sn laminated together.

[0030] Furthermore, a resin layer containing a metal filler may be provided between the base electrode layer 160, which is composed of a baked layer, and the plating layer 170. This resin layer can be formed by going through the same process as the process in which the base electrode layer 160 is formed in the manufacturing method of the multilayer ceramic capacitor according to this embodiment, which will be described in detail later (see steps S811 to S814 in Figure 5 later).

[0031] The base body 110 has a plurality of internal electrode layers 118 and a plurality of dielectric layers 119 that are alternately stacked along the stacking direction T.

[0032] The multiple internal electrode layers 118 include multiple first internal electrode layers 118a and multiple second internal electrode layers 118b. The multiple first internal electrode layers 118a and multiple second internal electrode layers 118b are stacked alternately in the stacking direction T.

[0033] The first internal electrode layer 118a is drawn out to the first end face 115. The first end face 115 is covered by the first external electrode 120. The first external electrode 120 is electrically connected to the first internal electrode layer 118a. The second internal electrode layer 118b is drawn out to the second end face 116. The second end face 116 is covered by the second external electrode 130. The second external electrode 130 is electrically connected to the second internal electrode layer 118b.

[0034] Although Figures 2 and 3 show examples in which seven first internal electrode layers 118a and seven second internal electrode layers 118b are provided, the number of each of the first internal electrode layers 118a and second internal electrode layers 118b is not particularly limited to seven.

[0035] The multiple dielectric layers 119 consist of an outer dielectric layer located between the first side surface 111 and the inner electrode layer 118 located on the first side surface 111 side in the stacking direction T, and between the second side surface 112 and the inner dielectric layer 118 located on the second side surface 112 side in the stacking direction T, and an inner dielectric layer located between adjacent inner electrode layers 118 in the stacking direction T.

[0036] Each of the first internal electrode layer 118a and the second internal electrode layer 118b contains Ni as its main component. Each of the first internal electrode layer 118a and the second internal electrode layer 118b may further contain a dielectric material of the same composition as the ceramic contained in the dielectric layer 119. Each of the first internal electrode layer 118a and the second internal electrode layer 118b may contain Sn at the interface with the dielectric layer 119.

[0037] Each of the multiple dielectric layers 119 is composed of a dielectric ceramic material, for example, a perovskite compound containing Ba and Ti as its main component. The dielectric layer 119 may also contain at least one additive selected from the group consisting of Si, Mg, Mn, V, Cr, and rare earth elements.

[0038] The base body 110 includes an inner layer portion C. The inner layer portion C has a capacitance by laminating in the stacking direction T a first internal electrode layer 118a at a portion facing a second internal electrode layer 118b adjacent in the stacking direction T and a second internal electrode layer 118b at a portion facing a first internal electrode layer 118a adjacent in the stacking direction T.

[0039] <B. Method for manufacturing a multilayer ceramic capacitor> FIG. 4 is a flowchart showing a method for manufacturing a multilayer ceramic capacitor according to an embodiment. FIG. 5 is a detailed flowchart of step S8 in the manufacturing flow shown in FIG. 4. FIGS. 6, 7, 11, and 15 are schematic front views for explaining each step of the manufacturing flow shown in FIG. 5. FIGS. 8 and 12 are schematic enlarged front views for explaining the movement of the base body in each step of the manufacturing flow shown in FIG. 5. FIGS. 9, 10, 13, and 14 are schematic plan views for explaining the movement of the base body in each step of the manufacturing flow shown in FIG. 5. Hereinafter, a method for manufacturing the multilayer ceramic capacitor 100 according to the present embodiment will be described with reference to FIGS. 4 to 15.

[0040] First, as shown in FIG. 4, a ceramic dielectric slurry is prepared (step S1). Specifically, a ceramic dielectric powder, an additive powder, a binder resin, a dissolving solution, etc. are dispersed and mixed. Thereby, a ceramic dielectric slurry is prepared.

[0041] The ceramic dielectric powder is, for example, perovskite dielectric particles such as BaTiO3, CaTiO3, SrTiO3, CaZrO3, or CaHfO3. The additive powder consists of, for example, at least one of Si compounds, Mg compounds, Mn compounds, Fe compounds, Cr compounds, Ni compounds, and Co compounds. As the binder resin, polyurethane resin, urea resin, melamine resin, epoxy resin, vinyl acetate resin, acrylic resin, or aqueous polymers such as polyvinyl alcohol (PVA) or polyvinyl butyral (PVB) can be used. These may be used individually or in mixtures of two or more. The ceramic dielectric slurry may be solvent-based or water-based. When the ceramic dielectric slurry is a water-based paint, the ceramic dielectric slurry is prepared by mixing a water-soluble binder and dispersant with dielectric raw materials dissolved in water.

[0042] Next, a ceramic dielectric sheet is formed (step S2). Specifically, the ceramic dielectric slurry is formed into a sheet on a carrier film using a die coater, gravure coater, or microgravure coater and then dried. This forms a ceramic dielectric sheet. From the viewpoint of miniaturizing and increasing the capacitance of the multilayer ceramic capacitor, the thickness of the ceramic dielectric sheet is preferably 0.4 μm or more and 0.8 μm or less.

[0043] Next, a mother sheet is formed (step S3). Specifically, a conductive paste is applied to a ceramic dielectric sheet so as to have a predetermined pattern. This forms a mother sheet on which a predetermined internal electrode pattern is provided on the ceramic dielectric sheet. The conductive paste contains Ni powder, a solvent, a dispersant, and a binder, and is prepared to have a constant viscosity. PVA or PVB can be used as the binder. Screen printing, inkjet printing, or gravure printing can be used as methods for applying the conductive paste. From the viewpoint of miniaturizing and increasing the capacitance of the multilayer ceramic capacitor, the thickness of the internal electrode pattern is preferably 0.3 μm to 0.8 μm. In addition to the mother sheet with the internal electrode pattern, a ceramic dielectric sheet that has not undergone step S3 is also prepared.

[0044] Next, multiple mother sheets are stacked (step S4). Specifically, a predetermined number of mother sheets consisting only of ceramic dielectric sheets and without an internal electrode pattern are stacked so that the thickness is, for example, between 10 μm and 30 μm. On top of that, a predetermined number of mother sheets with an internal electrode pattern are stacked. The number of stacked mother sheets with an internal electrode pattern is, for example, between 1 and 1000. Furthermore, a predetermined number of mother sheets consisting only of ceramic dielectric sheets and without an internal electrode pattern are stacked on top of that so that the thickness is, for example, between 10 μm and 30 μm. This constitutes a group of mother sheets.

[0045] Next, the mother sheets are pressed together to form a dielectric block (step S5). Specifically, the mother sheets are pressed together in the stacking direction by hydrostatic pressing or rigid pressing. This forms a dielectric block. At this time, the ceramic dielectric sheets are pressed at a predetermined temperature, causing them to adhere closely to each other. In addition, a ceramic dielectric sheet of a certain thickness is placed and pressed as the outermost layer in the stacking direction. This protects the dielectric sheet on which the internal electrode pattern is formed.

[0046] Next, the dielectric block is divided to form chips (step S6). Specifically, the dielectric block is divided into multiple chips by cutting, dicing, or laser cutting to form a matrix. When dividing the dielectric block, it may be heated and softened before division.

[0047] Next, the chip is fired (step S7). Specifically, the heating of the chip causes the dielectric material and conductive material contained in the chip to be fired, forming the base body 110. The firing temperature is, for example, 900°C to 1300°C. The firing temperature is set appropriately in accordance with the dielectric material and conductive material.

[0048] Next, the external electrodes are formed (step S8). As shown in Figure 5, step S8 includes steps S81 to S83, which will be described below.

[0049] First, the first external electrode 120 is formed (step S81). Step S81 further includes steps S811 to S815, which will be described below.

[0050] First, as shown in Figures 5 and 6, a conductive paste layer 51, which is a precursor to the external electrode, is formed on the flat plate portion 60 (step S811).

[0051] The conductive paste layer 51 is formed by a conductive paste 53 in which conductive particles are mixed with a binder, solvent, and dispersant, etc., and arranged in layers. The flat plate portion 60 is made of, for example, a metal material. The surface of the flat plate portion 60 extends in the horizontal direction.

[0052] Next, as shown in Figures 5 to 10, the base body 110 is immersed in the conductive paste layer 51 (step S812).

[0053] In detail, first, as shown in Figure 6, the multiple base body parts 110 are held by the holding part 20 such that each of the first end faces 115 of the multiple base body parts 110 faces the conductive paste layer 51. The holding part 20 is for holding the base body parts 110 such that one of the pair of end faces of the base body part 110 faces downward in the vertical direction.

[0054] The holding portion 20 includes a base layer 21 and an adhesive layer 22 provided on the main surface of the base layer 21. The base layer 21 is made of, for example, a metal material. The adhesive layer 22 is made of, for example, silicone rubber. In this embodiment, the base portion 110 is held by the holding portion 20 such that the second end face 116 of the base portion 110 is attached to the adhesive layer 22, causing the first end face 115 to face downward in the vertical direction.

[0055] An actuator 23 is attached to the holding part 20. Based on a signal from the control unit 90, the actuator 23 can move the holding part 20 in any direction. Specifically, the actuator 23 is driven so that the holding part 20 can move in three orthogonal axes: the length direction L, the width direction W, and the stacking direction T. The actuator 23 is composed of, for example, a servo motor, a stepping motor, or a robot cylinder, but the type of actuator 23 is not particularly limited to these.

[0056] The control unit 90 controls the operation of the actuator 23. The control unit 90 mainly consists of a CPU (Central Processing Unit) 91, a memory 92, and input / output devices (not shown) for inputting and outputting various signals. Note that the actuator 23, control unit 90, CPU 91, and memory 92 are not shown in Figure 7 and in Figures 11 and 15 described later.

[0057] The CPU 91 is responsible for executing programs. Memory 92 includes ROM (Read Only Memory) and RAM (Random Access Memory). ROM stores data non-volatilely. RAM stores data generated by the execution of programs by the CPU 91 volatilely.

[0058] Each component of the control unit 90 is connected to the others by a data bus. Processing in the CPU 91 is realized by each piece of hardware and software executed by the CPU 91. Such software is pre-stored in ROM / RAM. The control unit 90 is powered by an internal power supply (not shown) or an external power supply (not shown). For connection to the external power supply, for example, an AC adapter (not shown) is used.

[0059] As shown in Figure 7, the control unit 90 drives the actuator 23, causing the base body 110 to move downward. As a result, the base body 110 is immersed in the conductive paste layer 51 from the first end face 115 side.

[0060] Here, the base body 110 is moved downward along a virtual spiral trajectory ST. More specifically, the base body 110 is moved in a spiral motion along an axis of the base body 110 that is substantially parallel to the vertical direction.

[0061] The virtual spiral trajectory ST includes a portion where the radius of the virtual spiral trajectory ST, when viewed along the vertical direction, decreases as it moves from top to bottom. By moving the base body 110 in this way, the quality of the multilayer ceramic capacitor 100 can be stabilized, a point that will be described in detail later.

[0062] As shown in Figure 8, position P1 is defined as the vertical position of the first end face 115 where the corner 110a and the ridge 110b of the base body 110 are immersed in the conductive paste layer 51. Position P2 is defined as the vertical position of the first end face 115 where the first end face 115 of the base body 110 nearly reaches the bottom of the conductive paste layer 51. Here, "the corner 110a and the ridge 110b of the base body 110 are immersed in the conductive paste layer 51" means that the entire curved portion of the corner 110a and the entire curved portion of the ridge 110b are immersed in the conductive paste layer 51.

[0063] In this embodiment, the radius of the virtual helical trajectory ST when viewed along the vertical direction is maintained at radius R1 from the time the movement of the base body 110 along the virtual helical trajectory ST begins until the first end face 115 reaches position P1, as shown in Figures 8 and 9. Then, as shown in Figures 8 and 10, the radius of the virtual helical trajectory ST when viewed along the vertical direction gradually decreases from radius R1 as the first end face 115 moves from position P1 to position P2.

[0064] In other words, the radius of the virtual helical trajectory ST is maintained until the corner portion 110a and the ridge portion 110b are immersed in the conductive paste layer 51, and from the moment the corner portion 110a and the ridge portion 110b are immersed in the conductive paste layer 51, the radius of the virtual helical trajectory ST decreases as it moves from top to bottom.

[0065] The radius R1 is preferably 1.1 to 1.3 times half the length of the diagonal of the base body 110 in the WT plane. This effectively suppresses the occurrence of air bubbles, as will be described later, and allows a sufficiently thick conductive paste 53 to be applied to the base body 110.

[0066] As described above, the radius of the virtual helical trajectory ST after being reduced from radius R1 is preferably 1.01 times or more and 1.09 times half the length of the diagonal.

[0067] Next, as shown in Figure 5 and Figures 11 to 15, the base body 110 is lifted from the conductive paste layer 51 (step S813).

[0068] In detail, the control unit 90 drives the actuator 23, causing the base body 110 to move upward. This lifts the base body 110 away from the conductive paste layer 51.

[0069] Here, the base body 110 is moved upward along a virtual spiral trajectory ST. More specifically, the base body 110 is moved in a spiral motion along an axis of the base body 110 that is substantially parallel to the vertical direction.

[0070] The virtual helical trajectory ST includes a portion where the radius of the virtual helical trajectory ST, as viewed along the vertical direction, decreases as it moves from top to bottom. In other words, the virtual helical trajectory ST includes a portion where the radius of the virtual helical trajectory ST, as viewed along the vertical direction, increases as it moves from bottom to top. By moving the base body 110 in this way, the quality of the multilayer ceramic capacitor 100 can be stabilized, a point that will be explained in detail later.

[0071] As shown in Figure 12, position P3 is defined as the vertical position of the first end face 115 of the base portion 110, where the first end face 115 substantially reaches the bottom of the conductive paste layer 51. Position P4 is defined as the vertical position of the first end face 115 where the first end face 115 reaches the surface of the conductive paste layer 51.

[0072] In this embodiment, the radius of the virtual helical trajectory ST when viewed along the vertical direction gradually increases as the first end face 115 moves from position P3 to position P4, as shown in Figures 12 and 13, until the radius at position P4 becomes R2. Then, as shown in Figures 12 and 14, the radius of the virtual helical trajectory ST when viewed along the vertical direction is maintained at radius R2 as the first end face 115 moves from position P4 to the position where the lifting of the base body 110 is completed.

[0073] In other words, the radius of the virtual helical trajectory ST increases as it moves from bottom to top, and the radius of the virtual helical trajectory ST is maximized when the first end face 115 reaches the surface of the conductive paste layer 51.

[0074] As the base body 110 is pulled up from the conductive paste layer 51, as shown in Figure 11, the first end face 115 and the portions of the four sides near the first end face 115, and the conductive paste layer 51 are connected to each other by the conductive paste 53 stretched from the conductive paste layer 51.

[0075] The conductive paste 53 (hereinafter also referred to as "connecting paste 53a") connecting the first end face 115 and the portions of the four sides near the first end face 115 with the conductive paste layer 51 becomes thinner as the base body 110 is pulled away from the conductive paste layer 51. In other words, in the WT plane, the outer shape of the connecting paste 53a decreases as the base body 110 moves away from the conductive paste layer 51.

[0076] Then, as shown in Figure 15, the connecting paste 53a is torn off as the base body 110 is moved considerably away from the conductive paste layer 51. Here, the connecting paste 53a is more easily torn off at positions corresponding to the four sides of the base body 110, rather than at positions corresponding to the first end face 115 of the base body 110. This is because the base body 110 moves in a spiral motion.

[0077] Next, as shown in Figure 5, the conductive paste 53 is baked (step S814). Specifically, the conductive paste 53 applied to the first end face 115 and its surrounding area is heated, for example, in a drying oven, to form a baked layer that constitutes the base electrode layer 160. The baking temperature is, for example, 700°C to 900°C. Note that the baking temperature can be appropriately changed depending on the dielectric material and conductive material.

[0078] Next, as shown in Figure 5, a plating layer 170 (see Figure 2, etc.) is provided on the surface of the baked layer (step S815). This provides the first external electrode 120 on the first end face 115.

[0079] Next, as shown in Figure 5, the base body 110 is inverted (step S82). More specifically, first, a holding part 20 is prepared that has a configuration that is generally the same as the holding part 20 that holds the base body 110, but is constructed separately from the holding part 20. For the sake of explanation, the holding part 20 that holds the base body 110 will also be referred to as the first holding part, and the holding part 20 constructed separately from the first holding part will also be referred to as the second holding part.

[0080] Next, the second retaining part is positioned relative to the first retaining part so that the adhesive layer 22 of the second retaining part faces the first external electrode 120. Then, the first retaining part is moved relative to the second retaining part so that the first retaining part and the second retaining part are closer to each other. As a result, the first external electrode 120 is pressed against the adhesive layer 22 of the second retaining part.

[0081] Next, the first holding part, the second holding part, and the base body part 110 are inverted together so that their top and bottom are reversed.

[0082] Next, the first retaining part is moved relative to the second retaining part so that the first retaining part and the second retaining part are separated from each other. Here, the adhesive force of the adhesive layer 22 of the second retaining part is set to be stronger than the adhesive force of the adhesive layer 22 of the first retaining part. As a result, the base part 110 to which the first external electrode 120 is attached to the adhesive layer 22 of the second retaining part is peeled off from the adhesive layer 22 of the first retaining part.

[0083] As a result, the base body 110 is held by the second holding part such that the second end face 116 faces downward in the vertical direction.

[0084] Next, as shown in FIG. 5, a second external electrode 130 is formed on the second end face 116 (step S83). Step S83 further includes steps corresponding to the above-described steps S811 to S815. Since the contents of these steps are basically the same as those of steps S811 to S815, the description thereof is omitted.

[0085] Next, as shown in FIG. 4, the multilayer ceramic capacitor 100 is recovered (step S9). The recovery of the multilayer ceramic capacitor 100 is realized, for example, by inserting the tip of a recovery blade into the gap between the adhesive layer 22 of the second holding portion and the first external electrode 120 to remove the multilayer ceramic capacitor 100 from the second holding portion.

[0086] By going through the steps described above, the multilayer ceramic capacitor 100 can be manufactured according to the manufacturing method of the multilayer ceramic capacitor according to the present embodiment.

[0087] <C. Parentheses> In the manufacturing method of the multilayer ceramic capacitor according to the present embodiment, as described above, when the first external electrode 120 is provided on the element body 110, the element body 110 is immersed in the conductive paste layer 51 by being moved downward along the virtual spiral orbit ST.

[0088] Thereby, it is possible to effectively suppress the occurrence of air bubble entrainment in which air bubbles are entrapped in the gap between the element body 110 and the conductive paste 53 of the portion that becomes the first external electrode 120. This is because the inadvertently entrapped air bubbles in the above gap are pushed out from the above gap toward the outside by the spiral movement of the element body 110.

[0089] Further, when the element body 110 is immersed in the conductive paste layer 51, as described above, the virtual spiral orbit ST includes a portion where the radius of the virtual spiral orbit ST as viewed in the vertical direction decreases as it goes from above to below.

[0090] By moving the base body 110 along a virtual spiral trajectory ST with a relatively large radius, it becomes possible to apply a conductive paste 53 of sufficient thickness to the base body 110. Furthermore, by moving the base body 110 along a virtual spiral trajectory ST with a relatively small radius, it becomes possible to form the edges E (see Figures 11 and 15) of the conductive paste 53 applied to the four sides of the base body 110, which are located on the inside in the longitudinal direction L of the base body 110, in a substantially straight line.

[0091] Furthermore, in the manufacturing method of the multilayer ceramic capacitor according to this embodiment, as described above, when the first external electrode 120 is provided on the base body 110, the base body 110 is moved upward along a virtual helical trajectory ST, thereby being pulled up from the conductive paste layer 51. This also effectively suppresses the occurrence of air bubbles, as described above.

[0092] Furthermore, as the base body 110 is lifted from the conductive paste layer 51, as described above, the virtual helical trajectory ST includes a portion where the radius of the virtual helical trajectory ST, as viewed from the vertical, decreases as it moves from top to bottom (in other words, a portion where the radius of the virtual helical trajectory ST increases as it moves from bottom to top). This also makes it possible to apply a sufficiently thick conductive paste 53 to the base body 110, as described above, and to form the edge E of the conductive paste 53 in a substantially straight shape.

[0093] As described above, by using the manufacturing method for multilayer ceramic capacitors according to this embodiment, it becomes possible to manufacture a multilayer ceramic capacitor 100 in which the occurrence of bubble trapping is suppressed, sufficient thickness of the external electrodes is ensured, and the shape of the edges of the external electrodes, which are particularly prone to individual differences, is made into a substantially straight line.

[0094] Therefore, by configuring it as described above, a method for manufacturing electronic components with stable quality can be achieved.

[0095] Furthermore, among the effects achieved by the manufacturing method of the multilayer ceramic capacitor according to this embodiment described above, the effect of suppressing the occurrence of bubbles has been confirmed by verification tests described later.

[0096] Furthermore, in the manufacturing method of the multilayer ceramic capacitor according to this embodiment, as described above, in the step in which the base body 110 is immersed in the conductive paste layer 51, the radius of the virtual helical trajectory ST is maintained until the corner portion 110a and the ridge portion 110b are immersed in the conductive paste layer 51, and from the time the corner portion 110a and the ridge portion 110b are immersed in the conductive paste layer 51, the radius of the virtual helical trajectory ST decreases as it moves from top to bottom.

[0097] This allows the conductive paste 53 to be sufficiently applied to the corners 110a and ridges 110b, where it is generally difficult to form external electrodes of sufficient thickness, while also forming the edges E of the conductive paste 53 in a substantially straight shape.

[0098] Furthermore, in the manufacturing method of the multilayer ceramic capacitor according to this embodiment, as described above, in the step in which the base body 110 is pulled up from the conductive paste layer 51, the radius of the virtual helical trajectory ST increases as it moves from bottom to top, and the radius of the virtual helical trajectory ST is maximized when the first end face 115 reaches the surface of the conductive paste layer 51.

[0099] This makes it possible to easily tear off the connecting paste 53a. Furthermore, the connecting paste 53a is torn off at positions corresponding to the four sides of the base body 110. As a result, the thickness of the end-face side first external electrode 121 can be made thinner compared to the case where the connecting paste 53a is torn off at a position corresponding to the first end face 115 of the base body 110. Therefore, it becomes possible to miniaturize the multilayer ceramic capacitor 100. Note that this effect of being able to make the thickness of the end-face side first external electrode 121 thinner is more pronounced when the radius R2 is between 1.3 and 1.5 times half the length of the diagonal in the WT plane of the base body 110.

[0100] In the manufacturing method of the multilayer ceramic capacitor according to this embodiment, the example shows that the base body 110 is moved along a virtual helical trajectory ST in both the step of immersing the base body 110 in the conductive paste layer 51 and the step of pulling the base body 110 out of the conductive paste layer 51. However, the base body 110 only needs to be moved along the virtual helical trajectory ST in at least one of the two steps described above.

[0101] Furthermore, in the manufacturing method of the multilayer ceramic capacitor according to this embodiment, in the step of immersing the base body 110 in the conductive paste layer 51, the example given is that when the base body 110 is moved downward, it is always moved along a virtual helical trajectory ST. However, the base body 110 only needs to be moved downward along the virtual helical trajectory ST as described above, while at least a part of the base body 110 is immersed in the conductive paste layer 51. The same applies to the step of pulling the base body 110 out of the conductive paste layer 51.

[0102] Furthermore, in the method for manufacturing a multilayer ceramic capacitor according to this embodiment, after the step of immersing the base body 110 in the conductive paste layer 51, and before the step of pulling the base body 110 out of the conductive paste layer 51, the base body 110 may move in a spiral motion without vertical movement while immersed in the conductive paste layer 51.

[0103] Furthermore, in the manufacturing method of the multilayer ceramic capacitor according to this embodiment, in the step of immersing the base body 110 in the conductive paste layer 51, an example was given in which the first end face 115 of the base body 110 is immersed so as to substantially reach the bottom of the conductive paste layer 51. However, the base body 110 does not necessarily have to be immersed so that the first end face 115 substantially reaches the bottom of the conductive paste layer 51, and the first end face 115 may be immersed to a position spaced apart from the bottom of the conductive paste layer 51.

[0104] Furthermore, in the method for manufacturing a multilayer ceramic capacitor according to the present embodiment, in the step where the body part 110 is immersed in the conductive paste layer 51, the case where the virtual spiral orbit ST includes a portion where the radius of the virtual spiral orbit ST as viewed along the vertical direction is maintained at a predetermined radius has been exemplified. However, the virtual spiral orbit ST may not include a portion where the radius of the virtual spiral orbit ST as viewed along the vertical direction is maintained at a predetermined radius. In other words, the radius of the virtual spiral orbit ST as viewed along the vertical direction may continue to decrease from the start of the downward movement of the body part 110 until the completion of the movement. Similarly, in the step where the body part 110 is pulled up from the conductive paste layer 51, the radius of the virtual spiral orbit ST as viewed along the vertical direction may continue to increase from the start of the upward movement of the body part 110 until the completion of the movement.

[0105] Also, in the method for manufacturing a multilayer ceramic capacitor according to the present embodiment, the case where the holding part 20 including the base layer 21 and the adhesive layer 22 is used has been exemplified. However, instead of the holding part 20 having such a configuration, a holding part including a base layer in which a plurality of through holes are arranged in a lattice pattern and a substantially cylindrical adhesive part inserted into each of the plurality of through holes may be used.

[0106] In this case, the plurality of body parts 110 are held by the holding part by being inserted into each of the plurality of adhesive parts. Also, in this case, by pushing out the plurality of multilayer ceramic capacitors 100 from the through holes with pins or the like, the plurality of multilayer ceramic capacitors 100 can be transferred to a holding part configured separately from the holding part, or the plurality of multilayer ceramic capacitors 100 can be recovered.

[0107] <D. Verification Test> In this verification test, the occurrence rate of air bubbles in a multilayer ceramic capacitor manufactured based on the manufacturing method of a multilayer ceramic capacitor according to this embodiment (hereinafter also referred to as the multilayer ceramic capacitor according to the embodiment) was compared with the occurrence rate of air bubbles in a multilayer ceramic capacitor manufactured based on the manufacturing method of a multilayer ceramic capacitor according to the comparative example (hereinafter also referred to as the multilayer ceramic capacitor according to the comparative example). This verification was conducted to clarify the effects achieved by the manufacturing method of a multilayer ceramic capacitor according to this embodiment.

[0108] The manufacturing method of the multilayer ceramic capacitor according to the comparative example differs from the manufacturing method of the multilayer ceramic capacitor according to this embodiment only in that the base body 110 does not move along the virtual helical trajectory ST in steps S812 and S813 (see Figure 5) described above; all other points are the same.

[0109] The base body of the multilayer ceramic capacitors in the examples and comparative examples has dimensions of 1.0 mm in length, 0.5 mm in width, and 0.5 mm in thickness, excluding tolerances.

[0110] To check for the presence or absence of air bubbles, the multilayer ceramic capacitor was first polished so that the LT cross-section of the capacitor located in the center of the width direction W was exposed. Next, the cross-section was observed using an electron microscope or the like to check for the presence or absence of air bubbles. If air bubbles were present, a gap was created between the exposed part of the capacitor and the external electrode.

[0111] The sample size for both the multilayer ceramic capacitors in the example and the comparative example is 100 units. The occurrence rate of bubble trapping in the multilayer ceramic capacitors in the example is the total number of samples in which bubble trapping occurred divided by 100. The same applies to the occurrence rate of bubble trapping in the multilayer ceramic capacitors in the comparative example.

[0112] The results of this verification test showed that the occurrence rate of bubbles in the multilayer ceramic capacitor according to the comparative example was 3%. On the other hand, the occurrence rate of bubbles in the multilayer ceramic capacitor according to the embodiment was 0%. From these results, it was confirmed that the occurrence of bubbles can be suppressed by manufacturing a multilayer ceramic capacitor based on the manufacturing method of the multilayer ceramic capacitor according to this embodiment.

[0113] (First variation) Referring to Figures 12 to 14 described above, a method for manufacturing a multilayer ceramic capacitor according to the first modified example based on the above-described embodiment will now be explained.

[0114] The method for manufacturing a multilayer ceramic capacitor according to the first modified example differs from the method for manufacturing a multilayer ceramic capacitor according to the embodiment described above in that the virtual helical trajectory ST in step S813 is different.

[0115] In detail, as shown in Figure 12, position P5 is defined as the vertical position of the first end face 115 where the corner portion 110a and the ridge portion 110b are immersed.

[0116] In this modified example, the radius of the virtual helical trajectory ST when viewed along the vertical direction gradually increases as the first end face 115 moves from position P3 to position P5, as shown in Figures 12 and 13, until the radius at position P5 becomes R2. Then, as shown in Figures 12 and 14, the radius of the virtual helical trajectory ST when viewed along the vertical direction is maintained at radius R2 as the first end face 115 moves from position P5 to the position where the lifting of the base body 110 is completed.

[0117] Even with this configuration, effects similar to those described in the above-described embodiment can be obtained, resulting in a method for manufacturing electronic components with stabilized quality.

[0118] (Second variation) Figure 16 is a schematic front view illustrating step S813 of the manufacturing flow shown in Figure 5 in the manufacturing method of a multilayer ceramic capacitor according to the second modified example. The manufacturing method of a multilayer ceramic capacitor according to the second modified example based on the above-described embodiment will now be explained with reference to Figure 16.

[0119] As shown in Figure 16, the manufacturing method of the multilayer ceramic capacitor according to the second modified example differs from the manufacturing method of the multilayer ceramic capacitor according to the embodiment described above in that the direction of movement of the base body 110 in step S813 is different.

[0120] More specifically, in this modified example, the base body 110 is moved such that, while the base body 110 is being pulled up from the conductive paste layer 51, its axis, which is substantially parallel to the vertical direction, is moved in the in-plane direction of the first end face 115. That is, the base body 110 is pulled up from the conductive paste layer 51 diagonally upward.

[0121] Even with this configuration, effects similar to those described in the above-described embodiment can be obtained, resulting in a method for manufacturing electronic components with stabilized quality.

[0122] (Other forms, etc.) In the embodiments and modifications of the present disclosure described above, a multilayer ceramic capacitor was used as an example of an electronic component, and its manufacturing method was explained. However, the manufacturing method of the electronic component shown in these embodiments and modifications may also be applied to the manufacturing of other electronic components, such as a multilayer ceramic inductor or a multilayer ceramic thermistor. When the electronic component is a multilayer ceramic inductor, for example, the dielectric is made of magnetic ceramic and the internal electrodes are made of coil-shaped conductors. When the electronic component is a multilayer ceramic thermistor, for example, the dielectric layer is made of semiconductor ceramic.

[0123] Furthermore, the shape, configuration, size, number, material, etc., of each part shown in the embodiments and modified examples of the present disclosure described above can be modified in various ways, as long as they do not deviate from the spirit of the present disclosure.

[0124] Furthermore, the characteristic configurations shown in the embodiments and modifications of the present disclosure described above can naturally be combined with each other without departing from the spirit of the present disclosure.

[0125] Thus, the embodiments and their variations disclosed herein are illustrative in all respects and not restrictive. The technical scope of the present invention is defined by the claims and includes all modifications within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0126] 20 Holding part, 21 Base layer, 22 Adhesive layer, 23 Actuator, 51 Conductive paste layer, 53 Conductive paste, 53a Connecting paste, 60 Flat plate part, 90 Control unit, 91 CPU, 92 Memory, 100 Multilayer ceramic capacitor, 110 Base body part, 110a Corner part, 110b Ridge part, 110c Side ridge part, 111 First side, 112 Second side, 113 Third side, 114 Fourth side, 115 First end face, 116 Second end face, 118 Internal electrode layer, 118a First internal electrode layer, 118b Second internal electrode layer, 119 Dielectric layer, 120 First external electrode, 121 End face side first external electrode, 122 Side side first external electrode, 130 Second external electrode, 131 End face side second external electrode, 132 Side-side second external electrode, 160 base electrode layer, 170 plating layer, C inner layer, E edge, ST virtual helical trajectory.

Claims

1. A method for manufacturing an electronic component comprising a base body having a first end face and a second end face opposite to each other in the longitudinal direction, and four sides connecting the first end face and the second end face, and external electrodes provided on each of the first end face and the second end face, The process involves moving the base body downward so that the base body is immersed in the conductive paste layer, which is a precursor of the external electrode, from the first end face side, The process includes the step of immersing the base body portion in the conductive paste layer from the first end face side, and then moving the base body portion upward so that the base body portion is lifted out of the conductive paste layer, In at least one of the steps of immersing the base body in the conductive paste layer from the first end face side, and pulling the base body out of the conductive paste layer, the base body is moved up and down along a virtual helical trajectory. A method for manufacturing an electronic component, wherein, when viewed from the vertical, the virtual helical trajectory includes a portion where the radius of the virtual helical trajectory decreases as it moves from top to bottom.

2. The base portion includes a ridge portion which is the part where each of the four sides intersects with the first end face, and a rounded corner portion on the first end face side of each of the four sides. A method for manufacturing an electronic component according to claim 1, wherein in the step of immersing the base body in the conductive paste layer from the first end face side, the base body is moved downward along the virtual helical trajectory, the radius of the virtual helical trajectory is maintained until the ridge and corner portions are immersed in the conductive paste layer, and from the time the ridge and corner portions are immersed in the conductive paste layer, the radius of the virtual helical trajectory decreases as it moves from top to bottom.

3. A method for manufacturing an electronic component according to claim 1 or 2, wherein in the step of lifting the base body from the conductive paste layer, the base body is moved upward along the virtual helical trajectory, the radius of the virtual helical trajectory increases as it moves from bottom to top, and the radius of the virtual helical trajectory becomes maximum when the first end face reaches the surface of the conductive paste layer.

Images