KR20000003052A - External electrode forming of chip component - Google Patents

Abstract

PURPOSE: An external electrode forming of a chip component is provided to remove the plasticity process of the external electrode and to improve the contacting of the chip element with the external electrode. CONSTITUTION: An external electrode forming of a chip component comprises the steps of: printing the conductive pattern on the upper and lower ends of a laminate ceramic element; sintering the printed element; polishing the sintered element; and electroforming the external electrode on both sides of the polished element.

Description

External electrode formation method of chip parts

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an external electrode of a chip component by electroforming in the manufacture of a chip component such as a chip inductor or a multilayer ceramic capacitor (hereinafter, simply referred to as 'MLCC').

MLCC, a typical chip component, is composed of a ceramic element 1 and an external electrode (or terminal electrode) 2 as shown in FIG. 1A. The ceramic element 1 is formed of a metal oxide such as barium titanate, as shown in FIG. The metal forming the internal electrode 3 is laminated.

The MLCC is manufactured by firing chips formed by integrally stacking a ceramic dielectric and an internal electrode. Normally calcined MLCC, as shown in Fig. 1c, before the external electrode 2 is provided to prevent the internal electrode 3a of the body 1 from contracting and deteriorating the bond with the external electrode 2, as shown in Fig. 1d. Likewise, the internal electrodes 3b are protruded on both sides of the body through tumbling, and then external electrodes are formed on both sides of the body.

In order to form an external electrode that is combined with the protruding internal electrode, conventionally, the body 1 is impregnated in a conductive paste such as Pd or Ag, and then the desired amount of external electrode is applied, followed by electrode firing. However, the conventional paste coating method is complicated in that the process must be repeated after mounting, coating, and drying the body, and there is a limitation in making the external electrode have a constant shape and thickness. In addition, since the external electrodes are all expensive because they use precious metals, base metals such as Ni and Cu have recently been used as electrodes for cost reduction. For example, it is common to use Ni as an internal electrode and Cu as an external electrode. However, these metals have less interdiffusion than Pd or Ag pastes and are difficult to contact due to alloying, resulting in insufficient coupling between Ni as an internal electrode and Cu as an external electrode, thereby reducing capacity, loss coefficient, and series equivalent resistance (ESR). There is still a problem that the deterioration of the capacitor characteristics such as the rise of).

On the other hand, in order to solve the above problems caused by the formation of the external electrode in the manufacture of MLCC in the Republic of Korea Patent Publication No. 15-15432 and the conventional paste coating method in the state that the internal electrode to protrude more than the surface of the body after polishing of the body Alternatively, a method of first electroplating and then applying and firing an external electrode paste is disclosed. However, in the case of the above method, there is no suggestion regarding the specific electroplating conditions in the practical industry, and in particular, there is a problem of adhesion or cracking with external electrodes at both edges of the body 1, and thus the compactness of the external electrode structure itself is present. This lack tends to deteriorate the performance of the capacitor.

Accordingly, the present invention forms an external electrode of a chip component by using electroforming in barrel to solve the above problem, thereby improving adhesion between the chip body and the external electrode while eliminating the existing external electrode firing process. It is an object of the present invention to provide a method for forming an external electrode of a chip component.

1 is a view of a general chip component, FIG. 1A is a perspective view thereof, and FIGS. 1B to 1D are sectional views thereof.

2a to 2b is a structural diagram of a barrel plating apparatus according to the present invention

Figure 2c is a detailed view of the chip body and the medium embedded in the rotating container of Figure 2a

3A to D are cross-sectional views of chip components for explaining the process of the present invention.

Explanation of symbols on the main parts of the drawings

1 ..... Chip body 2 ..... External electrode

3 ..... Internal Electrode 4 ..... Conductive Media

5 ...... Electrolyte 10 .... Barrel Plating Equipment

11 ..... rotating container 12 .... cathode

13 ..... positive pole 15 .... rectifier

The present invention for achieving the above object is to print a base metal internal electrodes on a plurality of ceramic sheets, and by firing the laminated ceramic body by alternately stacking sheets printed with the internal electrode, and then fired In the method of manufacturing a chip component for polishing and forming an external electrode on both ends of the body,

Printing a conductive pattern on both upper and lower ends of the multilayer ceramic body, firing the body in which the conductive pattern is printed, and then polishing the fired body, and then transferring the external electrode layers to both sides of the polished body. The present invention relates to a method for forming an external electrode of a chip component.

Hereinafter, the present invention will be described in detail.

The pole for forming the external electrode of the present invention uses a barrel plating apparatus as shown in FIG. 2A and 2B show the schematic structure of the electroplating barrel plating apparatus 10 according to the present invention, and are deposited in the barrel plating tank 16 and the barrel plating tank 16 in which the electrolyte 5 is largely embedded. It consists of a rotary container (dangler) 11, the chip element 1 is contained, a rectifier 15 for supplying a current to the rotary container (11).

The rotary container 11 is configured to rotate by the electric motor 14, in which the chip body 1 and the medium 4 are mixed as shown in FIG. 2C. And, both ends of the rotating vessel 11 is connected to the cathode band 12 from the rectifier 15, the current is supplied through the medium (4). As the medium 4, steel balls or the like having electrical conductivity are mainly used.

The barrel plating tank 16 includes an electrolyte solution 5, and the electrolyte solution is provided with a positive electrode 13 connected to the rectifier 15.

Hereinafter, a method of forming an external electrode of the present invention through the plating apparatus will be described in detail.

The external electrode forming method of the chip component according to the present invention may be any chip element in which a plurality of internal electrodes are formed on a dielectric or ceramic sheet, in addition to the MLCC described above. Preferably, it is applied to a body having an interval of the inner electrode within 1/2 with respect to the thickness of the outer electrode to be formed. For example, in order to form a thickness of an external electrode about 200 µm, which is preferable for a chip component such as MLCC, it is preferable to apply to a printed chip component having a gap of up to 100 µm. That is, in the method of forming the external electrode of the present invention, as shown in FIG. 3B, since the plating layer is grown around one end of the internal electrode and connected to the plating layer formed on the neighboring internal electrode, when applied to a chip component with as many internal electrodes as possible. More preferred.

The chip body on which the internal electrodes are printed is cut after the internal electrodes are alternately stacked on a dielectric or ceramic sheet, and then fired, and the fired body exposes the internal electrodes to the outside through polishing. An external electrode is formed. The external electrode for the chip body of the present invention may be first electroplated in the order of Cu, Ni, Sn, or Sn / Pb, or both methods of electroplating the Ni, Sn, or Sn / Pb plating layer.

In the former case, the Cu plated layer may be poled in the range of 100 to 200 μm, and thereafter, the Ni plated layer may be formed to have a thickness of about 2 to 5 μm. That is, when forming a Cu layer, the Ni layer is plated to a minimum. On the other hand, in the latter case of forming only the Ni layer instead of the Cu layer, the thickness of the Ni plated layer is about 100 to 200 μm. It is preferable to perform Sn or Sn / Pb plating layer which electrophores in each layer both in thickness of 4-7 micrometers.

In the method of forming an external electrode for the chip body of the present invention, it is important to print the conductive patterns 1a and 1b on the upper and lower ends of both sides of the chip body 1 in advance as shown in Fig. 3A. The patterns 1a and 1b allow plating of Cu or Ni nonmetals on both upper and lower ends of the ceramic element as shown in FIG. The electric pole of the present invention begins to form a round plating layer around the inner electrode 3 on both sides of the body as shown in FIG. 3B. Later, as shown in FIG. 3C, a dense and uniform outer electroplating layer ( 2) is formed.

3 shows an example of a chip component having six internal electrodes, but the present invention is not limited thereto, and a chip component having a large number of internal electrodes is more advantageous to apply the present invention.

In the case of using barrel plating as shown in FIG. 2, the conductive medium 4 is charged into the rotary container 11 together with the chip body 1 having the conductive patterns formed on both upper and lower ends thereof, and the rectifier is rotated while rotating the rotary container 11. When the current is applied through 15), the external electrode layer is easily formed according to the electrolytic conditions and the type of the electrolyte. At this time, as shown in Figures 3b to 3c, it is necessary to appropriately adjust the electrolyte solution and the electrolytic conditions according to the formation of the external electrode by the pole.

Specifically, the Cu plating layer is copper sulfate: 180 ~ 220g / ℓ, sulfuric acid: 50 ~ 100g / ℓ, and chlorine ion: 20 ~ 100mg / ℓ using an electrolytic solution or copper pyrophosphate: 65 ~ 105g / ℓ, pyrophosphoric acid Gallium: 230 to 450 g / l, and ammonia: 1 to 5 mg / l containing an electrolyte solution can be used. At this time, when using a solution containing copper sulfate as the electrolyte solution, the Cu plating layer is 1 ~ 16A / dm while maintaining the temperature of the electrolyte in the temperature range of 25 ~ 30 ℃² It is preferable to give electric current density of and to roll. In the case of using a solution containing copper pyrophosphate as the electrolyte, the Cu plating bath has a pH of 8.2 to 9.0 and 1 to 8 A / dm while maintaining the temperature of the plating bath in the range of 50 to 60 ° C.² It is preferable to give electric current density of and to roll.

The Ni plated layer includes nickel sulfate: 350-600 g / l, nickel chloride: 20 g / l or less, boric acid: 40-50 g / l, stress relieving agent: 1-3 g / l, and anti-pitcher: 1-3 g / l It is preferable to use electrolyte solution. At this time, the electrolyte is preferably in the pH range of 3.5 to 4.5, the temperature of the solution in the range of 40 ~ 60 ℃. In addition, when forming the Ni plating layer, the current density is 1 to 16 A / dm from the rectifier 15.² It is preferable to give in the range of. In addition, the Ni plating layer of the present invention is preferably poled to form a thickness of 100 ~ 200㎛.

The Sn or Sn / Pb plating is preferably performed by applying a current density of 3 A / dm ² or less.

3D shows an external electrode layer formed in the order of the Cu layer 2, the Ni plating layer 6, and the Sn layer 7 according to the present invention.

Hereinafter, the present invention will be described in detail through examples.

Example 1

After firing the MLCC body after firing, the paste is printed on both upper and lower ends of the body, and the outer electrode is transferred to Cu / Ni / Sn-Pb on both sides of the chip body using barrel plating as shown in FIG. 2A. It was.

In the case of Cu plating, the temperature is 27 ° C., and its composition is 8 A / dm in an electrolyte solution containing copper sulfate: 200 g / l, sulfuric acid: 75 g / l, and chlorine ion: 60 mg / l.² The current density was given to the pole. The thickness of the formed Cu plating layer was about 150 micrometers.

In the case of Ni plating, the pH is 4, the temperature is 50 ° C., and the composition is nickel silpamate: 400 g / l, nickel chloride: 20 g / l, boric acid: 45 g / l, PO80 (juam doe industry) : 2 g / l, Naurisulfate as anti-pitcher: 2A / dm current density in electrolyte containing 2g / l² Applied in the range of to pole. The Ni plating layer was formed to a thickness of about 5 mu m. And, Sn / Pb plating layer is 0.01A / dm²The current density of was applied and the thickness was made into about 5 micrometers.

The MLCC prepared as described above had an excellent adhesion between the external electrode and the ceramic dielectric, and did not have cracks and formed an external electrode having a dense plating layer.

Example 2

After firing and polishing the MLCC body, paste was printed on both upper and lower ends of the body, and the external electrodes were transferred in the order of Ni / Sn to both sides of the chip body using barrel plating as shown in FIG. 2A.

The same electrolytic solution as in Example 1 was used, and the current density was 10 A / dm.² Applied in the range of to pole. The Ni plating layer was formed to a thickness of about 150 μm.

The Sn / Pb plating layer was applied with a current density of 0.01 A / dm ² , and the thickness thereof was about 5 μm.

The MLCC prepared as described above had an excellent adhesion between the external electrode and the ceramic dielectric, and did not have cracks and formed an external electrode having a dense plating layer.

As described above, the external electrode forming method for the chip body of the present invention has the advantage that it is easy to manufacture a chip component provided with an external electrode having a constant formation and thickness since the process is simple and does not require a firing process as compared to the conventional paste process.

As described above, according to the present invention, unlike the conventional paste coating method for forming the external electrode of the chip component, the adhesion between the chip element and the external electrode is improved while eliminating the existing external electrode firing process by using an appropriate electroforming process. An external electrode of a chip component is obtained, and this method of forming an external electrode has a useful effect of being very advantageous for the large-scale production of a chip component in which a plurality of sheets and internal electrodes are stacked.

Claims (16)

Base metal internal electrodes are printed on a plurality of ceramic sheets, and the laminated ceramic bodies are fired by alternately stacking sheets printed with internal electrodes, and then, the fired bodies are polished and externally disposed at both ends of the bodies. In the method of manufacturing a chip component for forming an electrode, Printing conductive patterns on both upper and lower ends of the multilayer ceramic body, firing the body on which the conductive pattern is printed, and then polishing the fired body, and then electroforming external electrode layers on both sides of the polished body. External electrode forming method of the chip component, characterized in that The method of claim 1, wherein the external electrode is applied to a body in which a spacing of the inner electrode is within 1/2 of a thickness to be formed. The method of claim 2, wherein the internal electrode spacing of the body is within at least 100㎛. The method of claim 2, wherein the external electrode is formed by electroforming in the order of Cu, Ni, Sn, or Sn / Pb. The method of claim 4, wherein the Cu plating layer is formed by electroforming the thickness in the range of 100 ~ 200㎛ The method of claim 4, wherein the Ni-plated layer is characterized in that the thickness in the range of 2 ~ 5㎛ The method of claim 2, wherein the external electrode is formed by electroforming in order of Ni, Sn, or Sn / Pb. The method of claim 7, wherein the Ni plating layer is formed by electroforming the thickness in the range of 100 ~ 200㎛ The method of claim 4 or 7, wherein the Sn or Sn / Pb plating layer is formed by electroforming with a thickness of 4 ~ 7㎛ The method of claim 4, wherein the Cu plating is performed in a plating bath containing copper sulfate: 180-220 g / l, sulfuric acid: 50-100 g / l, and chlorine ion: 20-100 mg / l. The method of claim 10, wherein the Cu plating is 1 ~ 16A / dm in a state in which the temperature of the plating bath is maintained in the range of 25 ~ 30 ℃² The method characterized in that the electric pole by giving the current density of The method of claim 4, wherein the Cu plating is performed in a plating bath containing copper pyrophosphate: 65-105 g / l, gallium pyrophosphate: 230-450 g / l, and ammonia: 1-5 mg / l. The method of claim 12, wherein the Cu plating is 1 ~ 8A / dm in a state in which the pH of the plating bath is in the range of 8.2 ~ 9.0 and the temperature is maintained in the range of 50 ~ 60 ℃² The method characterized in that the electric pole by giving the current density of The method of claim 4 or 7, wherein the Ni plating is silpamate nickel: 350 ~ 600g / l, nickel chloride: 20g / l or less, boric acid: 40 ~ 50g / l, stress remover: 1-3g / l, and Anti-pitcher: Method characterized in that performed by electroplating in a plating bath containing 1 ~ 3g / ℓ 15. The method of claim 14, wherein the Ni plating has a current density of 1 to 16 A / dm in a plating bath having a pH in the range of 3.5 to 4.5 and a temperature in the range of 40 to 60 ° C.² Method characterized by the fact that the electric pole The method of claim 9, wherein the Sn or Sn / Pb plating is performed by applying a current density of 3 A / dm ² or less.