MULTILAYER ELECTRONIC COMPONENT

An example embodiment of the present disclosure provides a multilayer electronic component including an external electrode including an electrode layer and a conductive resin layer disposed on the electrode layer. The conductive resin layer includes conductive particles including at least one of Cu particles, Cu3Sn and Cu6Sn5, and a resin, and in cross-sections of the conductive resin layer, a ratio of an area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5 is 1.88% to 38.89%, and a ratio of an area occupied by Cu6Sn5 to the total area occupied by the Cu particles, Cu3Sn and Cu6Sn5 is 31.54% to 97.23%.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims benefit of priority to Korean Patent Application No. 10-2022-0175793 filed on Dec. 15, 2022, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

A multilayer ceramic capacitor (MLCC), a multilayer electronic component, is a chip-type condenser mounted on the printed circuit boards of various types of electronic products such as imaging devices, including a liquid crystal display (LCD) and a plasma display panel (PDP), computers, smartphones, and mobile phones, and serves to charge or discharge electricity therein or therefrom.

The multilayer ceramic capacitor may be used as a component of various electronic devices due to having a small size, ensuring high capacity and being easily mounted. With the miniaturization and high output power of various electronic devices such as computers and mobile devices, demand for miniaturization and high capacity of multilayer ceramic capacitors has also been increasing.

Meanwhile, conventionally, an external electrode having a two-layer structure of a sintered electrode layer and a conductive resin layer has been applied to protect a multilayer ceramic capacitor from tensile stress generated in a mechanical or thermal environment. However, when a high-temperature reflow environment is applied to the conductive resin layer, lifting defects may occur at an interface between the sintered electrode layer and a resin electrode layer due to out gas generated in the conductive resin layer.

In addition, a conductive resin layer is present in a form in which conductive metal particles are dispersed in a resin, and secures electrical connectivity through hopping conduction, which may cause a problem in that the conductive resin layer may have lower electrical connectivity than the sintered electrode layer.

In order to solve such a problem, a method for applying a conductive resin layer in which an intermetallic compound such as Cu3Sn, Cu6Sn5, or the like, is included in an external electrode may be considered. However, in order to more effectively prevent lifting defects at the interface between the sintered electrode layer and the resin electrode layer, it is necessary to appropriately adjust a presence ratio of Cu3Sn and Cu6Sn5.

SUMMARY

An aspect of the present disclosure is to prevent lifting defects from occurring due to out gas generated in a conductive resin layer.

An aspect of the present disclosure is to improve the electrical connectivity of the conductive resin layer.

An aspect of the present disclosure is to solve a problem in which the remaining Sn in the conductive resin layer is eluted to an outer surface of the conductive resin layer to reduce a plating property of multilayer electronic components.

However, the aspects of the present disclosure are not limited to the above-described contents, and may be more easily understood in the process of describing specific embodiments of the present disclosure.

According to an aspect of the present disclosure, a multilayer electronic component may include: a body in which a dielectric layer and an internal electrode are alternately arranged in a first direction, the body including first and second surfaces opposing each other in the first direction, third and fourth surfaces connected to the first and second surfaces and opposing each other in a second direction, and fifth and sixth surfaces connected to the first to fourth surfaces and opposing each other in a third direction; and an external electrode including an electrode layer disposed on the third and fourth surfaces and a conductive resin layer disposed on the electrode layer, and the conductive resin layer may include a resin and conductive particles including Cu particles, Cu3Sn, and Cu6Sn5, along the first and second directions, in a cross-section of the conductive resin layer, a ratio of an area occupied by Cu3Sn to a total area occupied by the Cu particles, Cu3Sn and Cu6Sn5may be 1.88% to 38.89%, and a ratio of an area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn and Cu6Sn5may be 31.54% to 97.23%.

According to an aspect of the present disclosure, a multilayer electronic component may include: a body in which a dielectric layer and an internal electrode are alternately arranged in a first direction, the body including first and second surfaces opposing each other in the first direction, and third and fourth surfaces connected to the first and second surfaces and opposing each other in a second direction; and an external electrode including an electrode layer disposed on the third and fourth surfaces and a conductive resin layer disposed on the electrode layer, wherein the conductive resin layer includes a resin and conductive particles including Cu particles, Cu3Sn, and Cu6Sn5, and along the first and second directions, in a cross-section of the conductive resin layer, a ratio of an area occupied by Cu3Sn to a total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is 1.88% to 38.89%.

According to an exemplary embodiment in the present disclosure, it is possible to prevent lifting defects from occurring due to out gas generated in a conductive resin layer.

According to an exemplary embodiment in the present disclosure, it is possible to improve the electrical connectivity of the conductive resin layer.

According to an exemplary embodiment in the present disclosure, it is possible to solve a problem in which the remaining Sn in the conductive resin layer is eluted to an outer surface of the conductive resin layer to reduce a plating property of multilayer electronic components.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described with reference to specific example embodiments and the attached drawings. The embodiments of the present disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. The example embodiments disclosed herein are provided for those skilled in the art to better explain the present disclosure. In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements.

In addition, in order to clearly describe the present disclosure in the drawings, the contents unrelated to the description are omitted, and since sizes and thicknesses of each component illustrated in the drawings are arbitrarily shown for convenience of description, the present disclosure is not limited thereto. In addition, components with the same function within the same range of ideas are described using the same reference numerals. Throughout the specification, when a certain portion “includes” or “comprises” a certain component, this indicates that other components are not excluded and may be further included unless otherwise noted.

In the drawings, a first direction may be defined as a thickness T direction, a second direction may be defined as a length L direction, and a third direction may be defined as a width W direction.

FIG.1is a perspective view schematically illustrating a multilayer electronic component according to an example embodiment of the present disclosure.

FIG.3is an exploded perspective view schematically illustrating a body of the multilayer electronic component according to an example embodiment of the present disclosure.

FIG.5is an enlarged view of region K1ofFIG.2.

Referring toFIGS.1to5, a multilayer electronic component according to an aspect of the present disclosure may include a body110in which a dielectric layer111and internal electrodes121and122are alternately arranged in the first direction, and which includes first and second surfaces1and2opposing each other in the first direction, third and fourth3and4surfaces connected to the first and second surfaces1and2and opposing each other in the second direction, and fifth and sixth surfaces5and6connected to the first to fourth surfaces and opposing each other in the third direction, and external electrodes131and132including electrode layers131aand132adisposed on the third and fourth surfaces and conductive resin layers131band132bdisposed on the electrode layer, and the conductive resin layer may include conductive particles31aincluding at least one of Cu particles, Cu3Sn and Cu6Sn5, and a resin31b, and in first and second directional cross-section of the conductive resin layer, a ratio of an area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn and Cu6Sn5may be 1.88% to 38.89%, and a ratio of an area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn and Cu6Sn5may be 31.54% to 97.23%.

As described above, when the conductive resin layer is applied to protect the multilayer electronic component from stress generated in a mechanical or thermal environment, lifting defects may occur at an interface between the electrode layer and the conductive resin layer due to out gas generated in the conductive resin layer, and electrical connectivity may be reduced.

On the other hand, in the case of a multilayer electronic component100according to an example embodiment of the present disclosure, in the first and second directional cross-section of the conductive resin layers131band132b, since the ratio of the area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is 1.88% to 38.89%, and the ratio of the area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is 31.54% to 97.23%, the lifting defects may be prevented at the interface between the electrode layers131aand132aand the conductive resin layers131band132b, thereby providing the multilayer electronic component having excellent reliability.

Hereinafter, each component included in the multilayer electronic component100according to an example embodiment of the present disclosure will be described in more detail.

There is no particular limitation on the specific shape of the body110, but as illustrated, the body110may have a hexahedral shape or a similar shape thereof. Due to contraction of the ceramic powder including in the body110or grinding of corner portions of the body110during a sintering process, the body110may not have a hexahedral shape with a complete straight line, but may have a substantially hexahedral shape.

The body110may have first and second surfaces1and2opposing each other in the first direction, third and fourth surfaces3and4connected to the first and second surfaces1and2and opposing each other in the second direction, and fifth and sixth surfaces5and6connected to the first, second, third and fourth surfaces1,2,3and4and opposing each other in the third direction.

The body110may have the dielectric layer111and the internal electrodes121and122which are alternately stacked with one another. In a state in which a plurality of dielectric layers111forming the body110are sintered, boundaries between adjacent dielectric layers111may be so integrated so as to be difficult to identify without using a scanning electron microscope (SEM).

The dielectric layer111may be formed by producing a ceramic slurry including ceramic powder, an organic solvent and a binder, coating and drying the slurry on a carrier film to prepare a ceramic green sheet, and then sintering the ceramic green sheet. The ceramic powder is not particularly limited as long as it may obtain a sufficient capacitance, but for example, barium titanate based (BaTiO3) powder may be used as the ceramic powder.

An average thickness of the dielectric layer111does not need to be particularly limited, but may be, for example, 10 μm or less. In addition, the average thickness of the dielectric layer111may be arbitrarily set according to desired characteristics or uses. For example, for electronic components for a high voltage electrical apparatus, the average thickness of the dielectric layer111may be less than 4.8 μm, and for electronic components for small IT, the average thickness of the dielectric layer111may be 0.5 μm or less in order to achieve miniaturization and high capacity, but the present disclosure is not limited thereto.

Here, the average thickness of the dielectric layer111denotes the size of the dielectric layer111disposed between the internal electrodes121and122in the first direction. The average thickness of the dielectric layer111may be measured by scanning first and second directional cross-section of the body110with a scanning electron microscope (SEM) of 10,000× magnification. More specifically, the average value may be measured by measuring the thickness at multiple areas of one dielectric layer111, for example, 30 points which are spaced apart from each other at equal intervals in the second direction. The 30 points with the equal intervals may be designated in a capacity forming portion Ac described below. In addition, when the average value is measured by extending an average value measurement up to 10 dielectric layers111, the average size of the dielectric layers111may be further generalized. Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

The internal electrodes121and122may be alternately disposed with the dielectric layer111. For example, a pair of electrodes121and122having different polarities may be disposed to face each other with the dielectric layer111interposed therebetween. A plurality of first internal electrodes121and a plurality of second internal electrodes122may be electrically separated from each other by a dielectric layer111disposed therebetween. The first internal electrode121may be connected to the third surface, and the second internal electrode122may be connected to the fourth surface.

Conductive metal included in the internal electrodes121and122may be at least one of nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), and alloys thereof, but the present disclosure is not limited thereto.

The internal electrodes121and122may be formed by coating and sintering a conductive paste for internal electrodes including a conductive metal with a predetermined thickness on a ceramic green sheet. As a method for printing the conductive paste for internal electrodes, a screen printing method or a gravure printing method may be used, and the present disclosure is not limited thereto.

The average thickness of the internal electrodes121and122does not need to be particularly limited, but may be, for example, 3 μm or less. In addition, the average thickness of the internal electrodes121and122may be arbitrarily set according to desired characteristics or uses. For example, for electronic components for a high voltage electrical apparatus, the average thickness of internal electrodes121and122may be less than 1.3 μm, and for electronic components for small IT, the average thickness of internal electrodes121and122may be 0.4 μm or less in order to achieve miniaturization and high capacity, but the present disclosure is not limited thereto.

The average thickness of the internal electrodes121and122denotes the size of the internal electrodes121and122in the first direction. Here, the average thickness of the internal electrodes121and122may be measured by scanning first and second directional cross-section of the body110with a scanning electron microscope (SEM) of 10,000× magnification. More specifically, the average value may be measured by measuring the thickness at multiple areas of one internal electrode121or122, for example, 30 points which are spaced apart from each other at equal intervals in the second direction. The 30 points with the equal intervals may be designated in the capacity forming portion Ac described below. In addition, when the average value is measured by extending an average value measurement up to 10 internal electrodes121and122, the average size of the internal electrodes121and122may be further generalized. Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

The body110may include the capacity forming portion Ac which is disposed in the body110and in which the capacity is formed by including the first and second internal electrodes121and122alternately disposed with the dielectric layer111interposed therebetween, and a first cover portion112and a second cover portion113respectively disposed on opposite surfaces opposing each other in the first direction of the capacity forming portion Ac. The cover portions112and113may basically serve to prevent damage to the internal electrode due to physical or chemical stress. The cover portions112and113may have the same configuration as the dielectric layer111except that the cover portions112and113do not include internal electrodes.

The thickness of the cover portions112and113need not be particularly limited. However, for miniaturization and high-capacity of the multilayer electronic component, the average thickness of the cover portions112and113may be 100 μm or less, 30 μm or less, or 20 μm or less. Here, the average thickness of the cover portions112and113denotes average thicknesses of each of the first cover portion112and the second cover portion113.

The average thickness of the cover portions112and113may denote an average size of the cover portions112and113in the first direction, and may be a value obtained by averaging first directional sizes measured at five points spaced apart from each other at equal intervals in the first and second directional cross-section of the body110.

The body110may include margin portions114and115disposed on opposite surfaces opposing each other in the third direction of the capacity forming portion Ac. That is, the margin portions114and115may denote a region between opposite ends of the internal electrodes121and122in a cross-section in which the body110is cut in the first direction and the third direction and a boundary surface of the body110. In this case, the margin portions114and115may include a first margin portion114connected to the fifth surface5of the body110and a second margin portion115connected to the sixth surface6of the body110.

The margin portions114and115may include the same material as the dielectric layer111except that the margin portions114and115do not include the internal electrodes121and122. The margin portions114and115may basically serve to prevent damage to the internal electrodes121and122due to physical or chemical stress.

The margin portions114and115may be formed by coating and sintering the conductive paste for internal electrodes except for an area in which the margin portions will be formed on the ceramic green sheet. Alternatively, in order to suppress step portions by the internal electrodes121and122, the margin portion114and115may be formed by stacking a single dielectric layer or two or more dielectric layers on opposite surfaces opposing each other in the third direction of the capacity forming portion Ac.

The average thickness of the margin portions114and115need not be particularly limited. However, for miniaturization and high capacity of the multilayer electronic component, the average thickness of the margin portions114and115may be 100 μm or less, 20 μm or less, or 15 μm or less. Here, the average thickness of the margin portions114and115denotes average thicknesses of each of the first margin portion114and the second margin portion115.

The average thickness of the margin portions114and115may denote the average size of the margin portions114and115in the third direction, and may be a value obtained by averaging third directional sizes measured at five points which are spaced apart from each other at equal intervals in the first and third directional cross-sections of the body110.

The external electrodes131and132may be disposed on the third and fourth surfaces3and4of the body110and may extend partially on the first, second, fifth and sixth surfaces. The external electrode may include a first external electrode131disposed on the third surface and connected to the first internal electrode121and a second external electrode132disposed on the fourth surface and connected to the second internal electrode122.

The first external electrode131may include a first electrode layer131adisposed on the third surface, a first conductive resin layer131bdisposed on the first electrode layer, and a first plating layer131cdisposed on the first conductive resin layer131b.

The second external electrode132may include a second electrode layer132adisposed on the fourth surface, a second conductive resin layer132bdisposed on the second electrode layer, and a second plating layer132cdisposed on the second conductive resin layer132b.

The electrode layers131aand132amay serve to connect the internal electrodes121and122and the external electrodes131and132. The electrode layers131aand132amay include a first metal and glass, for example, Cu and glass. However, the present disclosure is not limited thereto, and the first metal included in the electrode layers131aand132amay be, for example, one or more of Cu, Ni, Pd, Ag, Au, Pt, Sn, Ti, and alloys thereof. Meanwhile, the glass included in the electrode layers131aand132amay serve to improve coupling force between the body110and the external electrodes131and132.

The electrode layers131aand132amay be formed by dipping the third and fourth surfaces3and4of the body110into a conductive paste including the first metal and glass, transferring a sheet including the first metal and glass, and then sintering the sheet.

Hereinafter, the first external electrode131will be described in more detail with reference toFIG.5. However, since the first external electrode131and the second external electrode132are symmetrical with respect to the second direction, the description of the first external electrode131may be identically applied to the second external electrode132.

The first conductive resin layer131bmay include conductive particles31aincluding at least one of metal particles31a1and a first intermetallic compound31a2, and a resin31b. The resin31bincluded in the first conductive resin layer131bmay basically serve to absorb impact applied to the multilayer electronic component. Accordingly, cracks may be prevented from occurring in the multilayer electronic component by absorbing stress or tensile stress applied when mounting the substrate. The resin31bincluded in the first conductive resin layer131bis not particularly limited, but may be, for example, a thermosetting resin.

The metal particles31a1included in the first conductive resin layer131bmay be Cu particles. However, the present disclosure is not limited thereto, and at least some of the plurality of metal particles31a1may be Ag particles. As illustrated inFIG.5, the metal particles31a1may be spherical particles in shape, but the present disclosure is not limited thereto, and the metal particles31a1may include one or more of spherical particles and flake-type particles.

Here, the spherical particles may include a shape that is not completely spherical, for example, a shape in which the length ratio (long axis/short axis) between a long axis and a short axis is 1.45 or less. The flake-type particles refer to particles having a flat and elongated shape, and the present disclosure is not particularly limited, but the flake-type particles may have, for example, a length ratio (long axis/short axis) between a long axis and a short axis of 1.95 or more. The lengths of the long axes and short axes of the spherical particles and the flake-type particles may be measured from an image obtained by scanning a cross-section of the first conductive resin layer131bcut in the first and second directions in the center of the body110in the third direction with the scanning electron microscope (SEM). Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

The first intermetallic compound31a2included in the first conductive resin layer131bmay include Cu3Sn and Cu6Sn5. The Cu3Sn and the Cu6Sn5may be formed by reacting the Cu particles with a low melting point metal including Sn or a Sn alloy during a drying and hardening heat treatment process of the first conductive resin layer131b.

The first intermetallic compound31a2may be formed in the first conductive resin layer131bin a network form, and at least a portion of the first intermetallic compound31a2may connect the first electrode layer131aand the first plating layer131c. Accordingly, it is possible to prevent lifting defects from occurring at an interface between the first electrode layer131aand the first conductive resin layer131b, and improve electrical connectivity in the first conductive resin layer131b.

According to an example embodiment of the present disclosure, in the first and second directional cross-section of the first conductive resin layer131b, a ratio of an area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is 1.88% to 38.89%, and a ratio of an area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is 31.54% to 97.23%.

Since Cu6Sn5has a higher reaction speed than Cu3Sn in a mutual reaction process between Cu and Sn, Cu6Sn5may be preferentially formed among Cu6Sn5and Cu3Sn. Meanwhile, when an environment richer in Cu than Sn is formed in the first conductive resin layer131bsimultaneously with forming Cu6Sn5, a portion of Cu6Sn5may achieve phase transition to Cu3Sn.

On the other hand, since a thermal expansion coefficient of Cu3Sn is larger than that of Cu6Sn5, Cu3Sn has a larger expansion rate by reflow application and a larger contraction rate at room temperature than those of Cu6Sn5. Accordingly, when a formation ratio of Cu3Sn in the first conductive resin layer131bis excessive, lifting defects of the first conductive resin layer due to expansion and contraction of Cu3Sn may occur. Therefore, it is important to effectively prevent the lifting defects by controlling the ratio of the area occupied by Cu6Sn5and the ratio of the area occupied by Cu3Sn.

Accordingly, the present inventors have found that in the first and second directional cross-section of the first conductive resin layer131b, when the ratio of the areas occupied by each of Cu3Sn and Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5satisfies the aforementioned range, the lifting defects can be effectively prevented from occurring at the interface between the first electrode layer131aand the first conductive resin layer131b

Accordingly, it is expected that in the first and second directional cross-section of the first conductive resin layer131b, when the ratio of the area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is less than 31.54%, or when the ratio of the area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is more than 38.89%, since the first intermetallic compound31a2is not sufficiently formed, or a ratio of the area of Cu3Sn with a high thermal expansion coefficient in the first intermetallic compound31a2is excessive, an anti-lifting effect may be reduced.

According to an example embodiment of the present disclosure, in the first and second directional cross-section of the first conductive resin layer131b, the ratio of the area occupied by the Cu particles to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5may be 0.3% or more. When the ratio of the area occupied by the Cu particles to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is less than 0.3%, since Sn may be excessively included in the first conductive resin layer131bas compared to the Cu particles, the remaining Sn may be eluted to the outer surface of the first conductive resin layer131b. Accordingly, since a uniform plating layer may not be formed on the first conductive resin layer131b, mounting characteristics may be reduced.

In addition, according to an example embodiment of this disclosure, in the first and second directional cross-section of the first conductive resin layer131b, the ratio of the area occupied by the Cu particles to the total area occupied by Cu particles, Cu3Sn, and Cu6Sn5may be 58.79% or less. When the ratio of the area occupied by the Cu particles to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5is more than 58.79%, it may be difficult to satisfy the area ratio of the Cu3Sn and the Cu6Sn5, and a large amount of out gas may be generated due to oxidation of the resin by the Cu particles.

In this case, the first and second directional cross-section of the first conductive resin layer131bmay be cross-sections cut from the center of the body110in the third direction. The ratio of the area occupied by Cu3Sn and the ratio of the area occupied by Cu6Sn5may be measured by observing the first and second directional cross-section of the first conductive resin layer131bcut from the center of the body110in the third direction at a magnification of 2000 times or more with the scanning electron microscope (SEM). Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

In addition, in the first and second directional cross-section of the first conductive resin layer131b, the ratio of the area occupied by Cu3Sn and the ratio of the area occupied by Cu6Sn5may be measured in a region in which a first directional size is 59 μm to 149 μm and a second directional size is 25 μm to 50 μm based on the center in the second direction.

However, the present disclosure is not limited thereto, and for example, the ratio of the area occupied by Cu3Sn and the ratio of the area occupied by Cu6Sn5may be measured in the second and third direction cross-sections of the first conductive resin layer131b.

In a method of distinguishing Cu particles, Cu3Sn, and Cu6Sn5included in the conductive particles31afrom each other, the Cu particles, Cu3Sn, and Cu6Sn5may be distinguished from each other by performing, through an energy dispersive spectroscopy (EDS), a component analysis on an image obtained by captured the first and second directional cross-section of the first conductive resin layer131busing the scanning electron microscope (SEM) and measuring a component ratio of Cu and Sn included in each region of the conductive particles31a. Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

In addition, in an image obtained by capturing the first and second directional cross-section of the first conductive resin layer131busing the scanning electron microscope (SEM), since the Cu particles among the Cu particles, Cu3Sn, and Cu6Sn5appear the darkest and Cu6Sn5appears the brightest, the Cu particles, Cu3Sn, and Cu6Sn5may be distinguished from each other using such a contrast difference.

The ratio of the areas occupied by each of the Cu particles, Cu3Sn, and Cu6Sn5may be measured by obtaining an image in which the first and second directional cross-section of the first conductive resin layer131bare captured with the scanning electron microscope (SEM) and then processing the image with an ImageJ program. Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

In an example embodiment, the conductive particles31amay further include Ag3Sn. The Ag3Sn may be disposed in the first intermetallic compound31a2. Ag3Sn may be an intermetallic compound formed by reacting Ag included in the Ag particles or a Sn alloy with Sn.

Meanwhile, Ag corresponds to a metal having high reactivity with Sn among metals. In this case, when Ag is excessively added to the first conductive resin layer131b, a bending strength of the multilayer electronic component100may be reduced due to excessive intermetallic compound formation. Accordingly, in the first and second directional cross-section of the first conductive resin layer131b, the ratio of the area occupied by Ag3Sn to the total area occupied by the conductive particles31amay be smaller than the ratio of the area occupied by Cu3Sn to the total area occupied by the conductive particles31a. In some embodiments, the total area occupied by the conductive particles31amay be the total area occupied by the Cu particles, Cu3Sn, Cu6Sn5, and Ag3Sn.

As described above, the ratio of the area occupied by Ag3Sn to the total area occupied by the conductive particles31aand the ratio of the area occupied by Cu3Sn to the total area occupied by the conductive particles31amay be measured by obtaining an image in which the first and second directional cross-section of the first conductive resin layer131bare captured with a scanning electron microscope (SEM) and then processing the image with the ImageJ program. Other methods and/or tools appreciated by one of ordinary skill in the art, even if not described in the present disclosure, may also be used.

The first conductive resin layer131bmay be formed by, for example, coating Cu powder, low melting point metal powder including Sn or Sn alloy powder and a conductive resin composition including a thermosetting resin on the first electrode layer131aand then performing a hardening heat treatment thereon. The thermosetting resin may be, for example, a bisphenol A resin, a glycol epoxy resin, a novolac epoxy resin, or a resin with a small molecular weight that is liquid at room temperature among these derivatives. The low melting point metal powder may include at least one of Sn, Sn96.5Ag3.0Cu0.5, Sn42Bi58and Sn72Bi28.

Meanwhile, a method of controlling the ratio of the area occupied by Cu3Sn and the ratio of the area occupied by Cu6Sn5does not need to be particularly limited. For example, as the content of Cu powder in the conductive resin composition increases as compared to the low melting point metal powder, and the hardening heat treatment time increases, the ratio of the area occupied by Cu3Sn may increase, but the present disclosure is not limited thereto.

FIG.6is a modified example ofFIG.5. As described above, since the first external electrode131and the second external electrode132are symmetrical to each other with respect to the second direction, the description of the first external electrode131may be identically applied to the second external electrode132.

Referring toFIG.6, in an example embodiment, the first external electrode131may include a first interface layer131ddisposed between the first electrode layer131aand the first conductive resin layer131band including a second intermetallic compound131d1. The second intermetallic compound131d1may be an intermetallic compound between the first metal included in the first electrode layer131aand the low melting point metal having a melting point lower than that of the first metal. For example, in the case where the first metal includes Cu and the low melting point metal includes Sn or a Sn alloy, the second intermetallic compound131d1may include Cu3Sn.

The first interface layer131dmay further include a glass131d2in contact with the first electrode layer131a. When the second intermetallic compound131d1is formed by a mutual reaction between metal of the first electrode layer131aand the low melting point metal including the Sn or Sn alloy, a glass exposed to the surface of the first electrode layer among the glasses included in the first electrode layer131amay be unreacted and remain, and the remaining glass131d2may form the first interface layer131dtogether with the second intermetallic compound131d1.

The first interface layer131dmay be continuously disposed on the first electrode layer or discontinuously disposed on the first electrode layer.

In an example embodiment, at least some of the conductive particles31amay connect the first interface layer131dand the first plating layer131c. Accordingly, electrical connection between the first interface layer131dand the first plating layer131ccan be improved, and lifting defects can be prevented at an interface between the first conductive resin layer131band the first interface layer131dand an interface between the first conductive resin layer131band the first plating layer131c.

The first plating layer131cmay improve mounting characteristics. The type of first plating layer131cis not particularly limited, and the first plating layer131cmay be a plating layer including nickel (Ni), tin (Sn), palladium (Pd), and/or alloys including the same, or may be formed of a plurality of layers. For example, the first plating layer131cmay include a first-first plating layer131c1and a first-second plating layer131c2sequentially stacked on the first conductive resin layer. For example, the first-first plating layer131c1may include Ni, and the first-second plating layer131c2may include Sn, but the present disclosure is not limited thereto.

Experimental Example

First, a body including a dielectric layer and an inner electrode was prepared, and then the third and fourth surfaces of the body were dipped into a conductive paste including conductivity and glass and are then sintered to prepare an electrode layer. Then, a conductive resin composition including Cu powder, low melting point metal powder including Sn, and a thermosetting resin was coated on the body on which the electrode layer was formed, and a Ni plating layer and a Sn plating layer were sequentially formed on the conductive resin layer to prepare a sample chip including the first and second external electrodes.

Then, after cutting the external electrodes in the first and second directions in the center of the body in the third direction, an image of the conductive resin layer was obtained by scanning the cross-sectional area of the conductive resin layer with the scanning electron microscope (SEM) under the condition in which an acceleration voltage was 10 kV, a working distance (WD) was 10.4 mm, an analysis magnification was 5000 times.

FIG.7Aillustrates an image obtained by capturing the first and second directional cross-section of the conductive resin layer with the scanning electron microscope (SEM).FIG.7Bis an image illustrating an area in which Cu particles are disposed among the areas indicated by the box indicated inFIG.7A.FIG.7Cis an image illustrating an area in which Cu3Sn is disposed among the areas indicated by the box indicated inFIG.7A.FIG.7Dis an image illustrating an area in which Cu6Sn5is disposed among the areas indicated by the box indicated inFIG.7A.

Referring toFIGS.7A to7D, the area indicated by the box indicated inFIG.7Ain which a first directional size is 59 μm to 149 μm and a second directional size is 25 μm to 50 μm based on the center of the second direction among the cross-sectional areas of the conductive resin layer was analyzed by energy dispersion spectroscopy (EDS), and accordingly, Cu particles, Cu3Sn, and Cu6Sn5were specified and then treated with the ImageJ program.

FIG.7Billustrates that among areas indicated by the box, an area in which the Cu particles are disposed is marked in black, and the rest is marked in white, andFIG.7Cillustrates that among areas indicated by the box, an area in which Cu3Sn is disposed is marked in black, and the rest is marked in white, andFIG.7Dillustrates that among areas indicated by the box, an area in which Cu6Sn5is disposed is marked in black, and the rest is marked in white.

Next, with regard to 10 samples for each test number through the images ofFIGS.7B to7D, after measuring the ratio of the areas of each of the Cu particles, Cu3Sn, and Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5, average values thereof are described in Table 1 below.

Whether or not a lifting phenomenon of Table 1 occurs was evaluated by mounting 80 samples for each test number on a substrate and then applying reflow to the mounted samples. Then, the samples mounted on the substrate were cut in the first and second directions, and then the first and second external electrodes of each sample were captured with X-rays, respectively. In this case, when a bright band is present in the external electrode, it was evaluated that the lifting phenomenon occurred, and the number of samples in which the lifting phenomenon occurred among the 80 samples is listed in Table 1 below.

Whether Sn is eluted or not was determined in the following operations. After cutting each sample in the first and second directions before forming the plating layer, the first external electrode and the second external electrode of each sample were captured with the scanning electron microscope (SEM), respectively, and then, these results were indicated as a case in which Sn is eluted (NG) and a case in which Sn is not eluted (OK) to the outer surface of the conductive resin layer.

Referring to Table 1, in Test Nos. 1 to 8, it was confirmed that the ratio of the area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5was 1.88% to 38.89%, and the ratio of the area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5was 31.54% to 97.23%, which did not result in lifting defects and Sn elution defects.

On the other hand, in Test Nos. 9 to 10 and 12 to 17, it was confirmed that the area occupied by Cu3Sn to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5was more than 38.89%, or the ratio of the ratio of the area occupied by Cu6Sn5to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5was less than 31.54%, which resulted in the lifting defects.

In addition, in Test No. 11, it was confirmed that the ratio of the area occupied by Cu particles to the total area occupied by the Cu particles, Cu3Sn, and Cu6Sn5was less than 0.3%, which resulted in defects in which Sn was eluted to the outer surface of the conductive resin layer. For this reason, the plating layer could not be formed on the conductive resin layer, and thus it was impossible to evaluate the occurrence of the lifting defects.

The present disclosure is not limited to the above-described embodiments and the accompanying drawings, and is intended to be limited by the appended claims. Therefore, those of ordinary skill in the art may make various replacements, modifications, or changes without departing from the scope of the present invention defined by the appended claims, and these replacements, modifications, or changes should be construed as being included in the scope of the present invention.

In addition, the expression ‘one embodiment’ used in the present disclosure does not mean the same embodiment, and is provided to emphasize and explain different unique characteristics. However, the embodiments presented above do not preclude being implemented in combination with the features of another embodiment. For example, although items described in a specific embodiment are not described in another embodiment, the items may be understood as a description related to another embodiment unless a description opposite or contradictory to the items is in another embodiment.