EMBEDDED MULTILAYER CERAMIC ELECTRONIC COMPONENT AND METHOD OF MANUFACTURING THE SAME, AND PRINTED CIRCUIT BOARD HAVING EMBEDDED MULTILAYER CERAMIC ELECTRONIC COMPONENT THEREIN

There is provided an embedded multilayer ceramic electronic component, including: a ceramic body including dielectric layers; first and second internal electrodes facing each other with the dielectric layers interposed therebetween; a first external electrode and a second external electrode formed on external surfaces of the ceramic body, the first external electrode being electrically connected to the first internal electrodes and the second external electrode being electrically connected to the second internal electrodes; and a plating layer formed on the first external electrode and the second external electrode, wherein a surface roughness of the ceramic body is 500 nm or greater and not greater than a thickness of a ceramic cover sheet and a surface roughness of the plating layer is 300 nm or greater and not greater than a thickness of the plating layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a perspective view showing an embedded multilayer ceramic electronic component according to an embodiment of the present invention.

FIG. 3is an enlarged view of part A ofFIG. 2.

Referring toFIGS. 1 to 3, an embedded multilayer ceramic electronic component according to the embodiment of the invention may include: a ceramic body10including dielectric layers1; first and second internal electrodes21and22facing each other with the dielectric layers1interposed therebetween; a first external electrode31and a second external electrode32formed on external surfaces of the ceramic body10, the first external electrode31being electrically connected to the first internal electrodes21and the second external electrode32being electrically connected to the second internal electrodes22; and a plating layer33formed on the first external electrode31and the second external electrode32. Here, a surface roughness of the ceramic body10may be 500 nm or greater and not greater than a thickness of a ceramic cover sheet50, and a surface roughness of the plating layer33may be 300 nm or greater and not greater than a thickness of the plating layer33.

Hereinafter, the multilayer ceramic electronic component according to the embodiment of the invention, in particular, a multilayer ceramic capacitor, will be described, but the present invention is not limited thereto.

In the multilayer ceramic capacitor according to the embodiment of the invention, “a length direction”, “a width direction”, and “a thickness direction” will be defined as ‘L’ direction, ‘W’ direction, and ‘T’ direction, ofFIG. 1. Here, the ‘thickness direction’ may be used in the same concept as a direction in which the dielectric layers are laminated, that is, ‘lamination direction’.

According to the embodiment of the invention, a raw material for forming the dielectric layers1is not particularly limited as long as sufficient capacitance can be obtained thereby. For example, the raw material may be a barium titanate (BaTiO3) powder.

As a material for forming the dielectric layers1, various ceramic additives, organic solvents, plasticizers, binders, dispersants, or the like may be added to powder, such as the barium titanate (BaTiO3) powder, depending on the objects of the present invention.

The average particle diameter of ceramic powder used in forming the dielectric layers1is not particularly limited, and may be controlled in order to achieve objects of the present invention, for example, to 400 nm or lower.

A material for forming the first and second internal electrodes21and22is not particularly limited. For example, the first and second internal electrodes21and22may be formed by using a conductive paste composed of at least one of precious metal materials, such as, palladium (Pd), palladium-silver (Pd—Ag) alloy, and the like, nickel (Ni), and copper (Cu).

The first and second external electrodes31and32may be formed on external surfaces of the ceramic body10in order to form capacitance, and may be electrically connected to the first and second internal electrodes21and22, respectively.

The first and second external electrodes31and32may be formed of the same conductive material as the first and second internal electrodes21and22, but are not limited thereto. For example, the first and second external electrodes31and32may be formed of copper (Cu), silver (Ag), nickel (Ni), or the like.

The first and second external electrodes31and32may be formed by coating a conductive paste, which is prepared by adding glass frit to metal powder, followed by the firing thereof.

Referring toFIGS. 2 and 3, in the multilayer ceramic electronic component according to the embodiment of the invention, the surface roughness of the ceramic body10may be 500 nm to the thickness of the ceramic cover sheet50, and the surface roughness of the plating layer33may be 300 nm to the thickness of the plating layer33.

The ceramic body10may include a capacitance forming part contributing to capacitance formation and a cover layer provided on at least one surface of upper and lower surfaces of the capacitance forming part. The ceramic cover sheet may denote the cover layer, and the thickness of the ceramic cover sheet50may denote a thickness of the cover layer.

If the surface roughness of the ceramic body10is 500 nm or smaller and the surface roughness of the plating layer33is 300 nm or smaller, delamination between the multilayer ceramic electronic component and a printed circuit board may not be rectified. If the surface roughness of the ceramic body10is greater than the thickness of the ceramic cover sheet50, and the surface roughness of the plating layer33is greater than the thickness of the plating layer33, cracks may occur.

In addition, in the case in which the surface roughness of the ceramic body10is 700 nm or greater and not greater than the thickness of the ceramic cover sheet50, and the surface roughness of the plating layer33is 500 nm or greater and not greater than the thickness of the plating layer33, the delamination between the multilayer ceramic electronic component and the printed circuit board may be improved and cracks may be prevented.

The surface roughness is the degree of fine unevenness generated on a surface when a metal surface is processed, and is called surface profile. The surface roughness is generated by tools used in processing, depending on process suitability, and due to surface scratches, rust, or the like. With respect to the degree of roughness, when a surface of an element is cut perpendicularly thereto, a predetermined curve is shown in a cut cross-section thereof. The height from the lowest point of the curve to the highest point of the curve is taken, which is referred to as center line average roughness and expressed by Ra.

In the present invention, the surface roughness of the ceramic body10is designated by Ra1and the center line average roughness of the plating layer33is designated by Ra2.

The thickness of the plating layer33may be greater than 4 μm and smaller than 15 μm.

If the case in which the thickness of the plating layer33is 4 μm, when the multilayer ceramic electronic component is embedded in a printed circuit board100, there may occur a problem that a conductive via hole140is connected to the ceramic body10at the time of processing the conductive via hole140. If the thickness of the plating layer33is 15 μm, cracks may occur in the ceramic body10due to stress of the plating layer33.

The surface roughness of sandpaper may be transferred to a surface of the ceramic body10by placing the sandpaper on the surface of the ceramic body10at the time of a compressing process, and this is to generate surface roughness on the surface of the ceramic body10. Here, the sandpaper may have a P value of 100 to 3000.

The ‘P’ of the sandpaper is a symbol for a particle size standard of the European Federation of European Producers of

FIG. 3is a schematic view showing center line average roughness (Ra1) of the ceramic body10and center line average roughness (Ra2) of the plating layer33.

Referring toFIG. 3, the multilayer ceramic electronic component according to the embodiment of the invention may satisfy 500 nm≦Ra1≦thickness of ceramic cover sheet and 300 nm≦Ra2≦thickness of plating layer, when the center line average roughness of the ceramic body10is designated by Ra1and the center line average roughness of the plating layer33is designated by Ra2.

The center line average roughness of the ceramic body10(Ra1) and the center line average roughness of the plating layer33(Ra2) are values obtained by calculating the roughness of the ceramic body10and the plating layer33having a surface with roughness, and may mean roughnesses of the ceramic body10and the plating layer33, which are respectively calculated by obtaining an average value based on an imaginary center line of the roughness.

Specifically, referring toFIG. 3, as for a method of calculating the center line average roughness of the ceramic body10(Ra1) and the center line average roughness of the plating layer33(Ra2), the imaginary center line may be drawn with respect to the roughness formed on one surface of each of the ceramic body10and the plating layer33.

Then, respective distances based on the imaginary center line of the roughness (e.g., r1, r2, r3. . . r13) are measured, and then an average value of the respective distances is calculated according to the following equation. Through the average value, the center line average roughness of the ceramic body10(Ra1) and the center line average roughness of the plating layer33(Ra2) may be determined.

A multilayer ceramic electronic component having excellent withstand voltage characteristics and improved adhesive strength with a printed circuit board may be realized, by controlling the center line average roughness of the ceramic body10(Ra1) and the center line average roughness of the plating layer33(Ra2) to satisfy 500 nm≦Ra1≦thickness of ceramic cover sheet and 300 nm≦Ra2≦thickness of plating layer, respectively.

In the multilayer ceramic electronic component according to another embodiment of the invention, overlapping descriptions with the multilayer ceramic electronic component according to the above-described embodiment of the invention will be omitted.

FIG. 4is a view showing a process of manufacturing an embedded multilayer ceramic electronic component according to an embodiment of the present invention.

Referring toFIG. 4, there is provided a method of manufacturing an embedded multilayer ceramic electronic component according to an embodiment of the invention, the method including: preparing ceramic green sheets including dielectric layers1(S1); forming internal electrode patterns on the ceramic green sheets by using a conductive paste for internal electrodes containing a conductive metal powder and a ceramic powder (S2); laminating the ceramic green sheets having the internal electrode patterns formed thereon, to thereby form the ceramic body10including the first internal electrodes21and the second internal electrodes22facing each other therein (S3); placing sandpaper on each of an upper surface and a lower surface of the ceramic body10and performing compressing thereon (S4); removing the sandpaper from the ceramic body10and firing the ceramic body10(S5); forming the first external electrode31and the second external electrode32on the upper and lower surfaces and end surfaces of the ceramic body10(S6); forming a plating layer33formed on the first external electrode31and the second external electrode32(S7); and applying a sand blasting method to the ceramic body10and the plating layer33formed on the first external electrode31and the second external electrode32to control surface roughnesses thereof (S8). Here, a surface roughness of the ceramic body10may be 500 nm or greater and not greater than the thickness of the ceramic cover sheet,50, and the surface roughness of the plating layer33may be 300 nm or greater and not greater than the thickness of the plating layer33.

As for the method of manufacturing the multilayer ceramic electronic component according to the embodiment of the invention, first, a slurry prepared by including powder such as barium titanate (BaTiO3) or the like is coated and dried on a carrier film, to thereby prepare a plurality of ceramic green sheets, and this allows formation of dielectric layers.

The ceramic green sheet may be prepared by mixing a ceramic powder, a binder, and a solvent to prepare the slurry, and molding the slurry into a sheet shape having a thickness of several μm using a doctor blade method.

The conductive metal powder may be at least one of silver (Ag), lead (Pd), platinum (Pt), nickel (Ni), and copper (Cu).

In addition, the ceramic body10may include barium titanate (BaTiO3).

The placing of the sandpaper on each of the upper surface and the lower surface of the ceramic body10(S4) is provided to form the surface roughness of the ceramic body10. When sandpaper having a P value of 100 to 3000 is applied, artificial roughness may be formed. In this case, since only the roughness of a part of the surface of the ceramic body10is increased, only the surface roughness of the ceramic body10may be formed without affecting reliability of the multilayer ceramic electronic component.

In the forming of the plating layer33on the first external electrode31and the second external electrode32(S6), the sand blasting method is applied in order to artificially form the surface roughness of the first external electrode31and the second external electrode32after the firing of the ceramic body10is completed. The sand blasting method may also increase only the surface roughness of the first external electrode31and the second external electrode32, and thus does not affect reliability of the multilayer ceramic electronic component.

The other descriptions of the same features as the foregoing multilayer ceramic electronic component according to the embodiment of the present invention will be omitted.

FIG. 5is a cross-sectional view showing a printed circuit board having an embedded multilayer ceramic electronic component therein according to an embodiment of the present invention.

Referring toFIG. 5, there is provided the printed circuit board100having an embedded multilayer ceramic electronic component therein according to an embodiment of the invention, the printed circuit board including: an insulating substrate110; and an embedded multilayer ceramic electronic component including: the ceramic body10including the dielectric layers1; the first internal electrodes21and the second internal electrodes22disposed to face each other with the dielectric layers1interposed therebetween; the first external electrode31and the second external electrode32formed on external surfaces of the ceramic body10, the first external electrode31being electrically connected to the first internal electrodes21and the second external electrode32being electrically connected to the second internal electrodes22; and the plating layer33formed on the first external electrode31and the second external electrode32. Here, a surface roughness of the ceramic body10may be 500 nm or greater and not greater than a thickness of the ceramic cover sheet and a surface roughness of the plating layer may be 300 nm or greater and not greater than a thickness of the plating layer.

The insulating substrate110may include an insulating layer120, and, as necessary, may include a conductive pattern130and the conductive via hole140which constitute various types of interlayer circuits, as exemplified inFIG. 5. This insulting substrate11may be the printed circuit board100including a multilayer ceramic electronic component therein.

After being embedded in the printed circuit board100, the multilayer ceramic electronic component is subjected to several severe environments during post processes such as thermal treatment and the like, in a similar manner to the printed circuit board100. In particular, shrinkage and expansion of the printed circuit board100due to a thermal treatment process are directly transferred to the multilayer ceramic electronic component embedded in the printed circuit board100, thereby applying stress to an adhesive surface between the multilayer ceramic electronic component and the printed circuit board100. If the stress applied to the adhesive surface between the multilayer ceramic electronic component and the printed circuit board100is stronger than adhesive strength therebetween, delamination defects may occur, such as the adhesive surface may be delaminated.

The adhesive strength between the multilayer ceramic electronic component and the printed circuit board100is proportional to electrochemical binding force between the multilayer ceramic electronic component and the printed circuit board100and the effective surface area of the adhesive surface. Therefore, the delamination between the multilayer ceramic electronic component and the printed circuit board100can be reduced by controlling the surface roughness of the multilayer ceramic electronic component to increase the effective surface area of the adhesive surface between the multilayer ceramic electronic component and the printed circuit board100. In addition, the frequency of delamination of the adhesive surface between the multilayer ceramic electronic component and the printed circuit board100depending on the surface roughness of the multilayer ceramic electronic component embedded in the printed circuit board100may be confirmed.

Hereafter, the present invention will be described in detail with reference to inventive examples, but is not limited thereto.

In order to confirm the frequency of delamination of the adhesive surface depending on the surface roughness of the embedded multilayer ceramic electronic component according to the embodiment of the invention, a board having a multilayer ceramic electronic component embedded therein is allowed to be left for 30 minutes and then the frequency of delamination was measured and investigated at a temperature of 85° C. and relative humidity of 85%, which corresponds to a general severe condition of a chip component for a mobile phone mother board (Severe Condition 1) and at a temperature of 125° C. and relative humidity of 85%, which corresponds to a severe condition according to higher functions of an application processor (AP) (Severe Condition 2) while the center line average roughness of the ceramic body10(Ra1) and the center line average roughness of the plating layer33(Ra2) were varied according to the thickness of the plating layer33.

Experimental results in the case in which the thickness of the plating layer33was 5 μm were tabulated in Table 1; experimental results in the case in which the thickness of the plating layer33was 9 μm were tabulated in Table 2; and experimental results in the case in which the thickness of the plating layer33was 12 μm were tabulated in Table 3.

As seen from Tables 1 to 3 above, it can be seen that, as the surface roughness of the ceramic body10and the plating layer33becomes lower, the frequency of delamination is increased, and thus it can be confirmed that the surface roughness of the multilayer ceramic electronic component can affect occurrence of delamination.

In order to prevent delamination between the multilayer ceramic electronic component and the printed circuit board100and pass the reliability standard in the sever condition for evaluation reliability of the chip component for a mobile phone mother board (Severe Condition 1), surface roughness values of the ceramic body10and the first and second external electrodes31and32need to satisfy 500 nm or greater and 300 nm or greater, respectively. In order to pass the more severe condition (Severe Condition 2), surface roughness values of the ceramic body10and the plating layer33need to satisfy 700 nm or greater and 500 nm or greater, respectively.

In the case in which the thickness of the plating layer33is 4 μm, there may occur a problem that the conductive via hole140is connected up to the ceramic body10at the time of processing the conductive via hole140, and thus the effect of surface roughness was not confirmed. In the case in which the thickness of the plating layer33is 15 μm, cracks may occur in the ceramic body10due to stress of the plating layer33. Therefore, the thickness of the plating layer33may satisfy 4 μm<thickness of plating layer<15 μm.

In addition, the surface roughness of the ceramic body10may not be thicker than the thickness of the ceramic cover sheet and the surface roughness of the plating layer33may not be thicker than the thickness of the plating layer33, and thus, the maximum value of the surface roughness of the ceramic body10is limited to the thickness of the ceramic cover sheet50, and the maximum value of the surface roughness of the plating layer33is limited to the thickness of the plating layer.

As set forth above, according to the embodiments of the present invention, the sandpaper is placed on the surface of the ceramic body at the time of compressing of the ceramic body, to thereby transfer the roughness of the sandpaper to the ceramic body, and then the external electrodes are plated to form the plating layer, so that the surface roughness of the ceramic surface of the multilayer ceramic electronic component and the surface roughness of the plating layer can be controlled, thereby rectifying the delamination between the multilayer ceramic electronic component and the printed circuit board and thus improving adhesive characteristics.