JP2008112758A - Electronic component and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component in which intrusion of plating liquid into an underlying electrode film can be suppressed in plating, and to provide its manufacturing process. <P>SOLUTION: An outer electrode 3 includes an underlying electrode film 31, a protective film 32, and plating films 33 and 34. The underlying electrode film 31 is formed on the surface of an electronic component body 1. The protective film 32 is formed on the upper layer of the underlying electrode film 31 by vacuum film deposition. The plating films 33 and 34 are formed on the upper layer of the protective film 32 by electroplating. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component, and more particularly to an electronic component having an improved external electrode structure. Furthermore, the present invention relates to a method for manufacturing such an electronic component.

  The external electrodes of electronic components are required to have various characteristics such as heat resistance during soldering and solder wettability. Therefore, in order to satisfy these characteristics simultaneously, an external electrode having a structure in which a plurality of films is stacked is known. For example, Patent Document 1 discloses an external electrode having a structure in which a base electrode film, a Ni plating film, and a Sn plating film are sequentially stacked. The base electrode film is made of a sintered metal formed by applying and baking a Cu electrode paste. The Ni plating film and the Sn plating film are formed by a plating method such as electrolytic plating.

  A problem in the disclosed technique of Patent Document 1 is that when forming a Ni plating film or a Sn plating film, the plating solution tends to enter the base electrode film. The base electrode film is made of sintered metal and has a large number of holes on the surface, so that the plating solution easily enters the base electrode film. When the plating solution enters the inside of the base electrode film, the plating solution may ooze out to the outside as time passes, and the surface of the external electrode may be eroded. For this reason, it becomes difficult to prevent appearance defects due to discoloration of the external electrode surface and mounting defects due to a decrease in solder wettability.

However, since the plating method has a high film growth rate and is easy to handle, it is desirable to use the plating method from the viewpoint of improving the mass productivity of electronic components.
JP 2005-44875 A

  The subject of this invention is providing the electronic component which can suppress the penetration | invasion of the plating solution to a base electrode film in the case of plating, and its manufacturing method.

  In order to solve the above-described problems, an electronic component according to the present invention includes an electronic component main body and an external electrode. The external electrode includes a base electrode film, a protective film, and at least one plating film. The base electrode film is formed on the surface of the electronic component main body. The protective film is a film formed by a vacuum film formation method, and is formed in an upper layer of the base electrode film. The at least one plating film is a film formed by electroplating, and is formed in an upper layer of the protective film.

  In the electronic component according to the present invention described above, the external electrode includes a base electrode film, a protective film, and at least one plating film. The protective film is a film formed by a vacuum film formation method, and is formed in an upper layer of the base electrode film. The vacuum film forming method includes both a PVD (physical vapor deposition) method and a CVD (chemical vapor deposition) method. The vacuum film-forming method is a film-forming method that vaporizes the target once in a vacuum compared to the electroplating method that grows the plating film in the plating solution and the method that applies and burns the conductive paste, so the film structure is dense. It becomes.

  Furthermore, at least one plating film is a film formed by electroplating, and is formed in the upper layer of the protective film. In order to form such a plating film, even if a plating solution is allowed to act on the surface of the protective film, since the protective film has a dense film structure, the plating solution does not penetrate into the protective film. Therefore, it is possible to prevent the plating solution from entering the base electrode film positioned below the protective film.

  Furthermore, this invention provides the manufacturing method of an electronic component. In the electronic component manufacturing method according to the present invention, an electronic component including an electronic component main body and a base electrode film formed on the surface of the electronic component main body is prepared. Next, a protective film is formed on the base electrode film by a vacuum film forming method. Furthermore, at least one plating film is formed on the protective film by electroplating.

  According to the above-described method for manufacturing an electronic component, it is possible to prevent the plating solution from entering the base electrode film as in the case of the electronic component described above.

  As described above, according to the present invention, it is possible to provide an electronic component and a method for manufacturing the same that can suppress the penetration of the plating solution into the base electrode film during plating.

  FIG. 1 is a cross-sectional view showing an embodiment of an electronic component according to the present invention. The illustrated electronic component includes an electronic component main body 1 and external electrodes 3 and 4. In the illustrated embodiment, the present invention is applied to a multilayer ceramic capacitor, but can also be applied to other multilayer electronic components such as a multilayer inductor.

  The electronic component body 1 is made of, for example, a ceramic material mainly composed of barium titanate, and is typically a ceramic sintered body. The electronic component main body 1 has a substantially rectangular parallelepiped shape defined by a length direction X, a width direction Y, and a thickness direction Z. The two end surfaces 11 and 12 facing the length direction X and the width direction Y are relative to each other. Two side surfaces (not shown), and an upper surface 13 and a lower surface 14 facing the thickness direction Z.

  A plurality of internal electrodes 2 are embedded in the electronic component main body 1. The internal electrodes 2 are stacked in the thickness direction Z extending in the length direction X and perpendicular to the length direction X with an interval between them in the electronic component body 1. Furthermore, the internal electrodes 2 are alternately drawn out to the end faces 11 and 12 of the electronic component main body 1. The internal electrode 2 is made of, for example, Cu or Ni.

  The external electrode 3 has a structure in which a base electrode film 31, a protective film 32, a first plating film 33 and a second plating film 34 are laminated, and is formed on the end surface 11, the upper surface 13 and the lower surface 14 of the electronic component body 1. It is formed straddling. Unlike the illustrated embodiment, the external electrode 3 may be formed only on the end surface 11 of the electronic component main body 1.

  First, the base electrode film 31 is a sintered metal film attached to the end surface 11, the upper surface 13, and the lower surface 14 of the electronic component body, and is connected to the internal electrode 2 on the end surface 11 of the electronic component body 1. The base electrode film 31 made of a sintered metal film is prepared by mixing a metal powder or an alloy powder with a binder and a solvent to prepare a conductive paste, and applying this conductive paste to the end surface 11, the upper surface 13 and the lower surface 14 of the electronic component body. And can be formed by baking. Examples of the sintered metal film include a sintered film of Cu, Ni, Ag, or Ag—Pd.

  Next, the protective film 32 is formed in an upper layer of the base electrode film 31. Specifically, the protective film 32 is directly attached to the surface of the base electrode film 31 and covers the entire surface of the base electrode film 31. Further, the protective film 32 extends to the tip of the edge portion 311 of the base electrode film 31 on the upper surface 13 and the lower surface 14 of the electronic component body. The protective film 32 is a film formed by a vacuum film formation method. Furthermore, the protective film 32 is preferably made of an electrically conductive material. Examples of the vacuum film forming method include a sputtering method, a PVD method (physical vapor deposition method), and a CVD method (chemical vapor deposition method). In the case of the sputtering method, the protective film 32 is a sputtered film of metal or alloy. Examples of the sputtered metal film include a sputtered film of Cu, Ni, Pd, or Ag.

  Next, the first plating film 33 is formed in the upper layer of the protective film 32. Specifically, the first plating film 33 is directly attached to the surface of the protective film 32 so as to cover almost the entire surface of the protective film 32. The first plating film 33 is a plating film by electroplating, and an example of the plating film is a Ni plating film.

  Finally, the second plating film 34 is formed in the upper layer of the first plating film 33. Specifically, the second plating film 34 is directly attached to the surface of the first plating film 33 so as to cover almost the entire surface of the first plating film 33. Similar to the first plating film 33, the second plating film 34 is also a plating film by electroplating, and an example of the plating film is a Sn plating film.

  Similar to the external electrode 3, the external electrode 4 has a structure in which a base electrode film 41, a protective film 42, a first plating film 43 and a second plating film 44 are laminated, and the end face 12 of the electronic component body 1. The upper surface 13 and the lower surface 14 are formed. Hereinafter, description of the external electrode 4 will be omitted, and the external electrode 3 will be representatively described.

  The second plating film 34 located at the uppermost layer in the external electrode 3 is an Sn plating film. The 2nd plating film which consists of Sn plating film plays the role which ensures the affinity with solder at the time of soldering.

  The first plating film 33 located below the second plating film 34 is a Ni plating film. The first plating film 33 made of Ni plating film has a role of ensuring heat resistance during soldering, and Sn in the second plating film 34 made of Sn plating film enters the inside of the electronic component main body 1. Play a role to prevent.

  The base electrode film 31 located below the first plating film 33 is a sintered metal film. The sintered metal film can be formed by applying and baking a conductive paste on the end face 11 of the electronic component main body, and can secure a considerable film thickness. Therefore, the end face 11 of the electronic component main body can be secured. It is suitable for connecting with the internal electrode 2 in FIG. However, the sintered metal film is porous and has a large number of pores on the surface. For this reason, when a plating solution is applied to the base electrode film 31 made of a sintered metal film, the plating solution tends to enter the base electrode film 31.

  Therefore, in the electronic component shown in FIG. 1, the protective film 32 is provided between the base electrode film 31 and the first plating film 33. The protective film 32 is a film formed by a vacuum film formation method. The vacuum film forming method has a dense film structure as compared with an electroplating method for growing a plating film in a plating solution and a method for applying and baking a conductive paste. Therefore, even if a plating solution is allowed to act on the surface of the protective film 32 in order to form the first plating film 33, the protective film 32 has a dense film structure, so that the plating liquid is difficult to penetrate into the protective film 32. . Therefore, it is possible to prevent the plating solution from entering the base electrode film 31 located below the protective film 32.

  The protective film 32 by the vacuum film forming method can be distinguished from a sintered metal film or a plating film by electroplating in that there are few impurities in the film.

  Further, as a result of examination by the inventors, when the base electrode film 31 is made of a sintered metal film, there is a possibility that the glass component deposited during the sintering adheres to the surface of the base electrode film 31. For this reason, even if a plating solution is applied to the surface of the base electrode film 31 by the electroplating method, there is a problem of defective plating such that the plating film does not adhere to the portion of the surface of the base electrode film 31 where the glass component is deposited. Can happen.

  In this regard, in the electronic component shown in FIG. 1, a protective film 32 is formed between the base electrode film 31 and the first plating film 33 by a vacuum film forming method. According to the vacuum film formation method, the protective film 32 can be attached to the portion of the surface of the base electrode film 31 where the glass component is deposited. By causing the plating solution to act on the surface of the protective film 32, the first plating film 33 can be adhered without defective plating.

  Furthermore, since the protective film 31 formed by the vacuum film forming method has a dense film structure, it is possible to improve the results of the high temperature load test and the moisture resistance load test required for the electronic component. The experimental results regarding the high temperature load test and the moisture resistance load test are shown in Table 1 below.

  In the experiment, a high temperature load test and a moisture resistance load test were performed on each sample 1 to 5, and a defect rate of the high temperature load test and a defect rate of the moisture resistance load test were examined. The number of data N for each sample 1 to 5 was 40. In sample 1, the protective film thickness of 0 μm means that no protective film was provided.

  As shown in Table 1, when the protective film was not provided on the upper layer of the base electrode film (Sample 1), the defect rate of the high temperature load test and the defect rate of the moisture resistance load test were both 100%.

  On the other hand, when the protective film was provided on the upper layer of the base electrode film (samples 2 to 5), the defect rate of the high temperature load test and the defect rate of the moisture resistance load test could be reduced. In particular, when the thickness of the protective film was 10 μm or more (samples 4 and 5), the failure rate of the high-temperature load test and the failure rate of the moisture resistance load test could both be suppressed to 0%.

  In the electronic component shown in FIG. 1, the protective film 32 is preferably made of the same material as the base electrode film 31. For example, when the base electrode film 31 is a Cu sintered film, the protective film 32 is preferably a Cu sputtered film. By forming the protective film 32 from the same material as the base electrode film 31, the adhesion of the protective film 32 to the base electrode film 31 can be improved.

  Further, as a result of examination by the inventor, the base electrode film 31 is basically made of a metal material and is a different material from the electronic component main body 1 made of a ceramic material. There is a possibility that the plating solution enters from between the edge portion 311 of the film 31 and the upper surface 13 of the electronic component main body 1 and eventually reaches the end surface 11 of the electronic component main body 1. The internal electrode 2 is drawn out to the end surface 11 of the electronic component body 1, and when the plating solution penetrates into the internal electrode 2, the characteristics of the internal electrode 2 are deteriorated.

  Therefore, in the electronic component shown in FIG. 1, the protective film 32 is formed so as to cover the entire surface of the base electrode film 31. According to this aspect, it is possible to prevent the plating solution from entering from between the edge portion 311 of the base electrode film 31 and the upper surface 13 of the electronic component main body 1, and thus prevent deterioration of the characteristics of the internal electrode 2.

  In the electronic component shown in FIG. 1, when the external electrode 3 is connected to the substrate with a conductive adhesive, the second plating film 34 of the external electrode 3 may be composed of an Au plating film.

Next, a method for manufacturing such an electronic component will be described with reference to FIGS.
First, as shown in FIG. 2, the base electrode film 31 is formed on the end surface 11, the upper surface 13, and the lower surface 14 of the electronic component body 1. The base electrode film 31 is formed so as to be connected to the internal electrode 2 on the end surface 11 of the electronic component main body 1. Specifically, a conductive paste is prepared by mixing a metal powder or an alloy powder with a binder and a solvent. Then, the conductive paste is applied to the end surface 11, the upper surface 13, and the lower surface 14 of the electronic component body and baked. The same applies to the formation of the base electrode film 32 on the end surface 12, the upper surface 13, and the lower surface 14 of the electronic component body 1. As a result, the electronic component 10 including the electronic component main body 1 and the base electrode films 31 and 32 is obtained.

  Next, as shown in FIG. 3, a protective film 32 is formed on the upper layer of the base electrode film 31 by a vacuum film forming method. Specifically, the protective film 32 is directly attached to the surface of the base electrode film 31 and is formed so as to cover the entire surface of the base electrode film 31. As an example of the vacuum film forming method, a case where a sputtering method is employed will be described. First, the electronic component body 1 is supported by the support 5 so that the entire surface of the base electrode film 31 is exposed. Next, in this state, the electronic component main body 1 is placed in an inert gas atmosphere such as argon gas. Then, ions are struck against the target in an inert gas atmosphere, and particles 61 such as metal atoms jumping out of the target are deposited on the surface of the base electrode film 31 to form the protective film 32. The same applies to the point that the protective film 42 is formed on the base electrode film 41.

After the step shown in FIG. 3, electroplating is performed as shown in FIG. Here, barrel plating is employed as one aspect of electroplating. More specifically, the electronic component 10 is put in the barrel container 79 together with the energization medium 77 and the barrel container 79 is immersed in the plating solution 63 together. The electronic component 10 is energized while rotating the barrel container 79. The plating solution 63 is a Ni plating solution for depositing a Ni plating film, and contains Ni ions (Ni ⁺ ). The electrode plate 73 is immersed in the plating solution 63 and connected to the DC power source 71.

  FIG. 5 is a diagram showing a state of the electronic component 10 in the process shown in FIG. As shown in FIGS. 4 and 5, the electrode plate 73 is an anode, the protective film 32 of the electronic component 1 is a cathode, and a DC voltage is applied between the electrode plate 73 and the protective film 32 by a DC power source 71. As a result, the first plating film 33 can be deposited on the surface of the protective film 32 using not only the original base electrode film 31 but also the protective film 32 as the base electrode film. The same applies to the point where the first plating film 42 is deposited on the surface of the protective film 42.

  In the electronic component manufacturing method described above, as shown in FIG. 3, the protective film 32 is formed on the upper layer of the base electrode film 31 by a vacuum film forming method. As described above, the film structure of the protective film 32 becomes dense.

  Next, as shown in FIG. 5, the plating solution 63 is allowed to act on the surface of the protective film 32 to deposit the first plating film 33. Even if the plating solution 63 is allowed to act on the surface of the protective film 32, the protective film 32 has a dense film structure, so that the plating solution 63 hardly penetrates into the protective film 32. Therefore, it is possible to prevent the plating solution 63 from entering the base electrode film 31 located below the protective film 32.

  Further, according to the vacuum film forming method, the protective film 32 can be attached to the portion of the surface of the base electrode film 31 where the glass component is deposited. By causing the plating solution 63 to act on the surface of the protective film 32, the first plating film 33 can be adhered without defective plating.

After the step shown in FIG. 5, electroplating is performed again as shown in FIG. Also in this electroplating, barrel plating similar to that shown in FIG. 4 can be adopted, and redundant description is omitted. The plating solution 65 is an Sn plating solution for depositing an Sn plating film, and contains Sn ions (Sn ⁺ ). Then, an electrode plate (not shown) is used as an anode, the first plating film 33 of the electronic component 1 is used as a cathode, and a DC voltage is applied between the electrode plate and the first plating film 33 by a DC power source. Thus, the second plating film 34 can be deposited on the surface of the first plating film 33 using not only the original base electrode film 31 but also the protective film 32 and the first plating film 33 as the base electrode film. it can. The same applies to the point where the second plating film 44 is deposited on the surface of the first plating film 43.

  As shown in FIG. 6, even if the plating solution 65 is allowed to act on the surface of the first plating film 33, the protective film 32 located below the first plating film 33 has a dense film structure. It is difficult for the plating solution 65 to penetrate 32. Therefore, the plating solution 65 can be prevented from entering the base electrode film 31.

  While the present invention has been described with reference to the embodiment, it is needless to say that the present invention is not limited to this embodiment, and various modifications and changes can be made within the scope of the claims.

It is sectional drawing which shows one Embodiment of the electronic component which concerns on this invention. It is a figure which shows one process included in one Embodiment of the manufacturing method of the electronic component based on this invention. It is a figure which shows the process after the process shown in FIG. FIG. 4 is a diagram showing a step after the step shown in FIG. 3. It is a figure which shows the state of an electronic component in the process shown in FIG. FIG. 6 is a diagram showing a step after the step shown in FIGS. 4 and 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic component main body 3, 4 External electrode 31, 41 Base electrode film 32, 42 Protective film 33, 43 1st plating film 34, 44 2nd plating film

Claims (8)

An electronic component including an electronic component body and an external electrode,
The external electrode includes a base electrode film, a protective film, and at least one plated film,
The base electrode film is formed on the surface of the electronic component body,
The protective film is a film formed by a vacuum film formation method, and is formed in an upper layer of the base electrode film,
The at least one plating film is a film formed by electroplating, and is formed in an upper layer of the protective film.
Electronic components. The electronic component according to claim 1,
The protective film is made of the same material as the base electrode film,
Electronic components. An electronic component according to claim 1 or 2,
The protective film is formed so as to cover the entire surface of the base electrode film.
Electronic components. An electronic component according to any one of claims 1 to 3,
The electronic component main body includes a plurality of internal electrodes therein, and the internal electrodes extend in a certain direction and are stacked at intervals from each other in a direction perpendicular to the certain direction. It is drawn out to the end face of the main body facing the fixed direction,
The base electrode film is provided on the end face of the electronic component main body, and is connected to the internal electrode at the end face.
Electronic components. An electronic component including an electronic component main body and a base electrode film formed on the surface of the electronic component main body is prepared,
A protective film is formed on the base electrode film by a vacuum film formation method,
A method for manufacturing an electronic component, wherein at least one plating film is formed on the protective film by electroplating. It is a manufacturing method of the electronic component according to claim 5,
The protective film is formed from the same material as the base electrode film.
Manufacturing method of electronic components. It is a manufacturing method of the electronic component according to claim 5 or 6,
The manufacturing method of the electronic component which forms the said protective film in the aspect which covers the whole surface of the said base electrode film. A method of manufacturing an electronic component according to claim 5,
The electronic component main body includes a plurality of internal electrodes therein, and the internal electrodes extend in a certain direction and are stacked at intervals from each other in a direction perpendicular to the certain direction. It is drawn out to the end face of the main body facing the fixed direction,
The base electrode film is provided on the end face of the electronic component main body, and is connected to the internal electrode at the end face.
Manufacturing method of electronic components.

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