KR20200138117A - Multilayered capacitor - Google Patents

Abstract

The present invention includes: a body including a laminated structure of a dielectric layer and a plurality of internal electrodes; and an external electrode disposed at an end of the body and including a conductive layer connected to the plurality of internal electrodes and a plating layer covering the conductive layer. The conductive layer includes nickel (Ni) and barium titanate (BT), and provides a multilayer capacitor having an area occupied by nickel of 30 to 65% with respect to the total area of the conductive layer. The present invention provides the multilayer capacitor with improved reliability in moisture resistance.

Description

Multilayer capacitor {MULTILAYERED CAPACITOR}

The present invention relates to a multilayer capacitor.

Multilayer capacitors are small, high-capacity guaranteed, and easy to mount, so they can be used in imaging devices such as liquid crystal displays (LCDs) and plasma display panels (PDPs), computers, and smartphones. It is installed on the circuit board of various electronic products such as mobile phones and plays a role of charging or discharging electricity.

Conventional multilayer capacitors are made of barium titanate (BaTiO ₃ ) as the main material, and after preparing and firing a body including an internal electrode made of nickel (Ni), the internal electrode is exposed to one surface of the body by dipping. An external electrode is formed by applying a conductive paste containing copper (Cu) and firing.

In this case, the copper component of the external electrode is in contact with the nickel component of the internal electrode to realize electrical characteristics.

Accordingly, a first firing process of firing a body including a dielectric layer and an internal electrode and a second firing process of firing again after applying the external electrode are required, and the manufacturing process is lengthened.

In addition, in order to attach the external electrode to one surface of the body, glass must be included in the conductive paste.

The glass causes cracks during the sintering process, and causes the plating solution to penetrate into the body due to elution of the glass in the plating process.

As a result, the physical properties of the multilayer capacitor are deteriorated and moisture resistance reliability is deteriorated.

Korean Patent Publication No. 2012-0068622 Japanese Patent Publication No. 2009-147178

An object of the present invention is to provide a multilayer capacitor with improved reliability in moisture resistance.

An aspect of the present invention is a body including a laminated structure of a dielectric layer and a plurality of internal electrodes; And an external electrode disposed at an end of the body and including a conductive layer connected to the plurality of internal electrodes, and a plating layer covering the conductive layer. The conductive layer includes nickel (Ni) and barium titanate (BT), and provides a multilayer capacitor having an area occupied by nickel of 30 to 65% with respect to the total area of the conductive layer.

In an embodiment of the present invention, the conductive layer may have an area occupied by nickel of 40 to 55% with respect to the total area of the conductive layer.

In an embodiment of the present invention, the multilayer capacitor may further include a conductive resin layer disposed between the conductive layer and the plating layer.

In an embodiment of the present invention, the plating layer may include a copper (Cu) plating layer, a nickel plating layer covering the copper plating layer, and a tin (Sn) plating layer covering the nickel plating layer.

In an embodiment of the present invention, the plating layer may include a nickel plating layer and a tin plating layer covering the nickel plating layer.

In an embodiment of the present invention, the plating layer may be a tin plating layer.

In one embodiment of the present invention, the body may have an average thickness of a dielectric layer of less than 2.8 µm, an average thickness of an internal electrode of less than 1 µm, and an average thickness of a dielectric layer greater than twice the average thickness of an internal electrode. .

In an embodiment of the present invention, the external electrode may include a head formed on one surface of the body and connected to the internal electrode, and a band portion extending from the head to a part of the mounting surface of the body.

In an embodiment of the present invention, the multilayer capacitor further includes a conductive resin layer disposed between the conductive layer and the plating layer, and the distance from the cross section of the body to the end of the band portion of the conductive layer is the conductive layer. It may be shorter than the distance to the end of the band portion of the resin layer.

In an embodiment of the present invention, the body includes first and second surfaces facing each other, and third and fourth surfaces connected to the first and second surfaces and facing each other, and one end with a dielectric layer therebetween. It may include a plurality of internal electrodes disposed to be alternately exposed through the third and fourth surfaces of the body.

According to an embodiment of the present invention, it is possible to improve the moisture resistance reliability of the multilayer capacitor.

1 is a schematic perspective view of a multilayer capacitor according to an embodiment of the present invention.
2A and 2B are plan views, respectively, illustrating first and second internal electrodes applied to the multilayer capacitor of FIG. 1.
3 is a cross-sectional view taken along line II′ of FIG. 1.
4 to 6 are cross-sectional views each showing a structure of an external electrode according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, embodiments of the present invention may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below.

In addition, embodiments of the present invention are provided to more completely describe the present invention to those with average knowledge in the art.

In the drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

In addition, components having the same function within the scope of the same idea shown in the drawings of each embodiment will be described with the same reference numerals.

In addition, "including" a certain element throughout the specification means that other elements may be further included, rather than excluding other elements unless specifically stated to the contrary.

Hereinafter, when a direction of the capacitor body 110 is defined to clearly describe an embodiment of the present invention, X, Y, and Z indicated in the drawings represent the length direction, the width direction, and the thickness direction of the capacitor body 110, respectively. .

Further, in the present embodiment, the Z direction can be used in the same concept as the stacking direction in which the dielectric layers are stacked.

1 is a perspective view schematically showing a multilayer capacitor according to an embodiment of the present invention, FIGS. 2A and 2B are plan views each showing first and second internal electrodes applied to the multilayer capacitor of FIG. 1, and FIG. 3 is It is a cross-sectional view taken along line I-I' of FIG.

1 to 3, the multilayer capacitor 100 according to the present embodiment includes a body 110 including a dielectric layer 111 and a laminated structure of first and second internal electrodes 21 and 122, and a first And second external electrodes 130 and 140.

The body 110 is obtained by stacking a plurality of dielectric layers 111 in the Z direction and then firing, and the boundary between the dielectric layers 111 adjacent to each other of the body 110 uses a scanning electron microscope (SEM). It can be integrated to the extent that it is difficult to confirm without doing so.

In this case, the body 110 may have a substantially hexahedral shape, but the present invention is not limited thereto.

Further, the shape and dimensions of the body 110 and the number of stacked dielectric layers 111 are not limited to those shown in the drawings of the present embodiment.

In this embodiment, for convenience of explanation, both surfaces of the body 110 facing each other in the Z direction are connected to the first and second surfaces 1 and 2, and are connected to the first and second surfaces 1 and 2, Both sides facing each other in the X direction are connected to the third and fourth sides (3, 4), connected to the first and second sides (1, 2), connected to the third and fourth sides (3, 4), and Y Both surfaces facing each other in the direction are defined as fifth and sixth surfaces 5 and 6.

In addition, in this embodiment, the mounting surface of the multilayer capacitor 100 may be the first surface 1 of the body 110.

The dielectric layer 111 may include a ceramic material having a high dielectric constant, for example, barium titanate (BaTiO ₃ )-based or strontium titanate (SrTiO ₃ )-based ceramic powder, etc., but sufficient capacitance can be obtained. The present invention is not limited thereto.

In addition, ceramic additives, organic solvents, plasticizers, binders and dispersants may be further added to the dielectric layer 111 in addition to the ceramic powder.

The ceramic additive may be, for example, a transition metal oxide or a transition metal carbide, a rare earth element, magnesium (Mg) or aluminum (Al).

The body 110 may include an active region as a portion contributing to the formation of a capacitor, and upper and lower covers 112 and 113 respectively formed on the upper and lower portions of the active region in the Z direction as upper and lower margins.

The upper and lower covers 112 and 113 may have the same material and configuration as the dielectric layer 111 except that they do not include internal electrodes.

The upper and lower covers 112 and 113 may be formed by stacking a single dielectric layer or two or more dielectric layers on the upper and lower surfaces of the active region in the Z direction, respectively, and basically, the first and second dielectric layers caused by physical or chemical stress. It may play a role of preventing damage to the internal electrodes 121 and 122.

The first and second internal electrodes 121 and 122 are electrodes to which different polarities are applied, and are alternately disposed along the Z direction with the dielectric layer 111 interposed therebetween, and one end of the body 110 is the third and fourth electrodes. It can be exposed through surfaces 3 and 4, respectively.

In this case, the first and second internal electrodes 121 and 122 may be electrically insulated from each other by the dielectric layer 111 disposed therebetween.

The ends of the first and second internal electrodes 121 and 122 alternately exposed through the third and fourth surfaces 3 and 4 of the body 110 are the third and fourth surfaces of the body 110 to be described later. The first and second external electrodes 131 and 132 disposed at (3 and 4) may be connected to each other to be electrically connected.

According to the above configuration, when a predetermined voltage is applied to the first and second external electrodes 131 and 132, electric charges are accumulated between the first and second internal electrodes 121 and 122.

In this case, the capacitance of the multilayer capacitor 100 is proportional to the overlapped area of the first and second internal electrodes 121 and 122 overlapping each other along the Z direction in the active region.

In addition, the material forming the first and second internal electrodes 121 and 122 is not particularly limited, for example, noble metal materials such as platinum (Pt), palladium (Pd), and palladium-silver (Pd-Ag) alloy And a conductive paste made of at least one of nickel (Ni) and copper (Cu).

In this case, the printing method of the conductive paste may use a screen printing method or a gravure printing method, and the present invention is not limited thereto.

Meanwhile, in the body 110 of the present embodiment, the average thickness of the dielectric layer 111 is less than 2.8 μm, the average thickness of the first and second internal electrodes 121 and 122 is less than 1 μm, respectively, and the dielectric layer 111 The average thickness of may be greater than twice the average thickness of the first or second internal electrodes 121 and 122.

The first and second external electrodes 130 and 140 are provided with voltages of different polarities, are disposed at both ends of the body 110 in the X direction, and expose the first and second internal electrodes 121 and 122 It can be connected to each of the parts to be electrically connected.

At this time, the first and second external electrodes 130 and 140 are formed on the surface of the body 110 to connect the first and second internal electrodes 121 and 122 to the first and second conductive layers 131 and 141. ), and first and second plating layers formed to cover the first and second conductive layers 131 and 141, respectively.

In addition, the first and second external electrodes 130 and 140 include first and second heads formed on the third and fourth surfaces 3 and 4 of the body 110, and the first and second heads. It may include first and second band portions respectively extending from the portion to a portion of the first surface 1 that is the mounting surface of the body 110.

In this case, the first and second band portions may further extend to a portion of the fifth and sixth surfaces 5 and 6 of the body 110 and a portion of the second surface 2 to improve adhesion strength.

The first conductive layer 131 includes nickel (Ni) and barium titanate (BT).

In addition, the first conductive layer 131 may have an area occupied by nickel of 30 to 65% with respect to the total area.

Further, more preferably, the first conductive layer 131 may have an area occupied by nickel of 40 to 55% of the total area.

The second conductive layer 141 includes nickel (Ni) and barium titanate (BT).

In addition, the second conductive layer 141 may have an area occupied by nickel of 30 to 65% with respect to the total area.

In addition, more preferably, the second conductive layer 141 may have an area occupied by nickel of 40 to 55% with respect to the total area.

When the area occupied by nickel with respect to the total area in the first or second conductive layers 131 and 132 exceeds 65%, the bonding with the internal electrode is excellent, but the bonding between the external electrode and the body is not good, so the bonding surface of the body The probability of occurrence of a crack in is increased, resulting in a problem that the moisture resistance reliability is deteriorated.

On the other hand, when the area occupied by nickel with respect to the total area of the first or second conductive layers 131 and 132 is less than 30%, electrical connectivity is degraded due to poor contact between the internal electrode and the external electrode, resulting in a multilayer capacitor 100 ), it may cause a problem that the capacity is lowered.

At this time, the first and second plating layers of the first and second external electrodes 130 and 140 are copper (Cu) plating layers 132 and 142, and nickel plating layers 133 covering the copper plating layers 132 and 142, 143) and the tin (Sn) plating layers 134 and 144 covering the nickel plating layers 133 and 143 may be included.

As another embodiment, referring to FIG. 4, the plating layers of the first and second external electrodes 130 ′ and 140 ′ are nickel plating layers 133 and 143 and a tin plating layer covering the nickel plating layers 133 and 143. (134, 144) may be included.

As another embodiment, referring to FIG. 5, the plating layers of the first and second external electrodes (!30" and 140") may be tin plating layers 134 and 144.

According to the present invention, since the first and second conductive layers 131 and 132 are made of sintered electrodes containing nickel, the bonding and density of the external electrode and the dielectric are superior compared to conventional sintered electrodes containing copper. It is possible to improve the moisture resistance reliability of the capacitor 100.

In addition, since the body 110 and the first and second external electrodes 130 and 140 can be simultaneously fired after forming the first and second conductive layers 131 and 132, the process is simplified and the manufacturing cost Can be reduced.

Meanwhile, referring to FIG. 6, first and second conductive resin layers 135 and 145 may be disposed between the first and second conductive layers 131 and 141 and the first and second plating layers.

The first and second conductive resin layers 135 and 145 may be formed to cover ends of the first and second conductive layers 131 and 141.

That is, the distance from the end of the first surface 1 of the body 110 in the X direction to the end of the band portion of the first and second conductive layers 131 and 141 is the first and second conductive resin layers 135, 145) is shorter than the distance to the end of the band part.

In addition, the first and second conductive resin layers 135 and 145 provide a stress absorption effect, and may include a conductive metal and epoxy.

In this case, the conductive metal may be copper or nickel.

Experiment example

Table 1 shows the test of the moisture resistance reliability of the body and the average capacity of the multilayer capacitor according to the change of the area NA occupied by nickel with respect to the total area TA of the first or second conductive layer.

At this time, the embodiment of the multilayer capacitor has a length and width of 20 mm and 12 mm, has an electrical characteristic of 10.0 uF, and an external electrode is manufactured to include nickel and barium titanate.

Thereafter, a plating layer was formed in one of the structures of FIGS. 3 to 5, and evaluation was performed on 400 samples for 24 hours under conditions of 95°C, 95%RH, and 15Vdc/um.

At this time, the ratio of the cross-sectional area observed the ratio of the cross-sectional area of the head in the conductive layer.

In addition, in Sample 1, as a comparative example, the conductive layer contains copper instead of nickel.

Plating layer
rescue NA/TA Invasion reliability
Defective count Average capacity One Fig. 4 - 10/400 105% 2 Figure 3 0.55 0/400 104% 3 Fig. 4 0.55 0/400 107% 4 Figure 5 0.55 0/400 105% 5 Figure 3 0.13 0/400 56% 6 Figure 3 0.21 0/400 75% 7 Figure 3 0.30 0/400 100% 8 Figure 3 0.41 0/400 106% 9 Figure 3 0.65 0/400 107% 10 Figure 3 0.68 3/400 105% 11 Figure 3 0.79 8/400 104% 12 Figure 3 0.95 13/400 106%

Referring to Table 1, in the case of Sample 1, which is a comparative example, poor moisture resistance was confirmed.

In addition, Samples 2 to 4 were obtained by fixing the NA/TA to 0.55 and changing the structure of the plating layer to FIGS. 3 to 5, respectively.Comparing Samples 2 to 4, the moisture resistance reliability was not confirmed, and the average capacity Also appeared almost similar.

Accordingly, it can be seen that there is no significant difference in moisture resistance reliability and average capacity according to the structure of the plating layer of FIGS. 3 to 5.

Samples 5 to 12 are obtained by forming a plated layer in the plated layer structure of FIG. 3 and changing the numerical value of NA/TA.

In the case of samples 10 to 12 in which the NA/TA exceeds 0.65, it can be confirmed that moisture resistance reliability failure occurs.

In addition, in the case of samples 5 and 6 with NA/TA of less than 0.30, moisture resistance reliability did not occur, but the nickel content was too small, resulting in poor contact between the internal electrode and the external electrode, and the average capacity was 56% and 75%, respectively. It can be seen that it is significantly lowered compared to 7.

Accordingly, it can be seen that the preferable numerical range of NA/TA that can prevent poor moisture resistance reliability while securing an average capacity is 0.3 to 0.65.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical matters of the present invention described in the claims. It will be obvious to those of ordinary skill in the field.

100: stacked capacitor
110: body
111: dielectric layer
112, 113: cover
121, 122: first and second internal electrodes
130, 130', 130", 130"': first external electrode
140, 140', 140", 140"': second external electrode
131, 141: first and second conductive layers
132, 142: first and second copper plating layers
133, 143: nickel plating layer
134, 144: tin plated layer
135, 145: first and second conductive resin layers

Claims (16)

A body including a dielectric layer and a stacked structure of a plurality of internal electrodes; And
An external electrode including a conductive layer disposed at an end of the body and connected to the plurality of internal electrodes, a plating layer covering the conductive layer, and a conductive resin layer disposed between the conductive layer and the plating layer; Including,
The conductive layer is a multilayer capacitor comprising nickel (Ni) and barium titanate (BT).
The method of claim 1,
The multilayer capacitor in which the internal electrode contains nickel.
The method of claim 1,
The plating layer includes a copper (Cu) plating layer, a nickel plating layer covering the copper plating layer, and a tin (Sn) plating layer covering the nickel plating layer.
The method of claim 1,
The plating layer includes a nickel plating layer and a tin plating layer covering the nickel plating layer.
The method of claim 1,
A multilayer capacitor in which the plating layer includes a tin plating layer.
The method of claim 1,
A multilayer capacitor in which the dielectric layer includes at least one of magnesium or rare earth elements.
The method of claim 1,
The body, the upper and lower portions are formed of upper and lower covers that do not include internal electrodes,
A multilayer capacitor in which the upper and lower covers are made of the same material as the dielectric layer.
The method of claim 1,
The internal electrode is a multilayer capacitor comprising at least one of platinum (Pt), palladium (Pd), palladium-silver (Pd-Ag) alloy, and copper (Cu).
The method of claim 1,
The conductive resin layer is a multilayer capacitor comprising a conductive metal and an epoxy.
The method of claim 9,
The multilayer capacitor in which the conductive metal is copper or nickel.
The method of claim 1,
The body is a multilayer capacitor having a thickness of the dielectric layer of less than 2.8㎛.
The method of claim 1,
The body is a multilayer capacitor having a thickness of the internal electrode of less than 1 μm.
The method of claim 1,
The body is a multilayer capacitor having a thickness of the dielectric layer greater than twice the thickness of the internal electrode.
The method of claim 1,
The external electrode includes a head formed on one surface of the body and connected to the internal electrode, and a band portion extending from the head to a part of the mounting surface of the body.
The method of claim 14,
In the cross section of the body, a distance to an end of the band portion of the conductive layer is shorter than a distance to an end of the band portion of the conductive resin layer.
The method of claim 1,
The thickness of the internal electrode is less than 1 μm, and the thickness of the dielectric layer is less than 2.8 μm.

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