JP3277804B2 - Plating method for ceramic electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for plating a ceramic electronic component.

[0002]

2. Description of the Related Art In a ceramic electronic component, a plating film is formed on an electrode provided on a ceramic body in order to increase heat resistance of the electrode or to improve solderability.

[0003]

The above-mentioned plating film is formed by immersing the ceramic body in a plating solution. However, a conventional plating solution is used to increase the plating speed.
An acid having an H of 6 or less was used.

[0004] However, when a plating film is formed using such an acidic plating solution, if the ceramic body contains a transition metal oxide, there is a problem that the strength is reduced.

[0005] The reason for the decrease in strength is that hydrogen ions in the acidic plating solution deprive transition metal oxides constituting the ceramic body of oxygen, and as a result, the transition metal becomes ions and becomes acidic. , Resulting in the ceramic body becoming thinner and thinner.

Accordingly, an object of the present invention is to prevent this reduction in strength.

[0007]

SUMMARY OF THE INVENTION In order to achieve this object, the present invention provides an internal electrode having a transition metal oxide.
A part of the internal electrode by chamfering the ceramic body
Is exposed outside the ceramic body, and then the ceramic
Annealing of the ceramic body, and then the ceramic
As if electrically connected to the internal electrodes exposed outside the body
An external electrode is provided on the surface of the ceramic body of
A plating film is formed on the surface of the substrate by using an alkaline solution having a pH higher than 7 as a plating solution, thereby achieving an intended purpose.

[0008]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, there is provided a ceramic element having an internal electrode and containing a transition metal oxide.
A part of the internal electrode is chamfered to make this ceramic
Exposed outside the ceramic body, and then
And then exposed outside the ceramic body
This ceramic element is electrically connected to the internal electrodes.
A method for plating a ceramic electronic component, wherein an external electrode is provided on a body surface, and a plating film is formed on the surface of the external electrode using an alkaline solution having a pH higher than 7 as a plating solution. , The pre-process by annealing
The surface of the ceramic body activated and roughened by chamfering
Deactivates, thereby causing this ceramic body surface
In addition to preventing the careless formation of plating films,
As a result, the use of an alkaline solution having a pH higher than 7 greatly reduces the concentration of hydrogen ions in the plating solution, so that the transition metal is less likely to be ionized and eluted into the plating solution. There is no thinning, and the strength does not decrease.

According to a second aspect of the present invention, there is provided a plating method for a ceramic electronic component according to the first aspect, wherein the transition metal oxide comprises at least one oxide of Mn, Ni, Co, Cu, Fe, and Cr. A method comprising: Mn, Ni, Co,
It is possible to prevent the strength of the transition metal oxide ceramic body made of at least one oxide of Cu, Fe, and Cr from decreasing.

Further, the invention according to claim 3 is the method for plating a ceramic electronic component according to claim 1 or 2, wherein the ceramic body is mainly composed of a transition metal oxide. It is possible to prevent a decrease in the strength of the ceramic body containing a metal oxide as a main component.

Further, the invention according to claim 4 is the method for plating a ceramic electronic component according to claim 3, wherein at least 80 at% of the ceramic body is composed of a transition metal oxide. It is possible to prevent a decrease in the strength of the ceramic body containing an oxide as a main component.

Further, the invention according to claim 5 is to form a ceramic body with an oxide of Mn as a main component, and to perform plating on the electrode surface using a plating solution having a pH higher than 7.6. Item 5. The method for plating a ceramic electronic component according to Item 1 or 4, wherein Mn is less likely to be rapidly ionized when the pH is higher than 7.6, so that elution into the plating solution does not occur. This can prevent a decrease in strength.

According to a sixth aspect of the present invention, there is provided the method for plating a ceramic electronic component according to any one of the first to fifth aspects, wherein the plating is performed at a low current density of 1 A / dm ² or less. This eliminates the inadvertent formation of a plating film on the surface of the ceramic body.

[0014]

[0015] The invention according to claim 7, an annealing temperature of 800 ° C. C. to 1100 ° C., at the annealing temperature below the temperature after application of the external electrodes, according to claim 1, baking the external electrodes to the ceramic body The method of plating a ceramic electronic component according to the above, wherein the annealing temperature is lower than the firing temperature of the ceramic body to suppress the fluctuation of the electrical characteristics of the ceramic body.

Furthermore the invention according to claim 8, the external electrodes Cu or after coating a conductive paste containing Ag on the ceramic body, in a neutral atmosphere, or in claim 1 which is formed by baking in a reducing atmosphere, The method of plating a ceramic electronic component according to the above, wherein the baking of the conductive paste in these atmospheres can increase the bonding strength between the external electrode and the ceramic body, but deprives the ceramic body surface of oxygen. Although activation is facilitated, if annealing is performed in advance, oxygen is less likely to be deprived from this surface, so that careless plating film formation on this surface does not occur.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a plating tank made of a synthetic resin having a resistance to a plating solution.
Is immersed. A large number of ceramic element bodies 4 and conductive balls 5 in the state shown in FIG. 3 are housed in the barrel 3, and are rotatably driven by a motor or the like (not shown).

As shown in FIG. 2, the ceramic body 4 is provided with two internal electrodes 6 on the upper and lower sides thereof opposed to each other at a predetermined interval. 68 at%), a composite of Ni oxide (23 at%) and Cu oxide (9 at%),
Sintered at 1200 ° C.

After sintering, chamfering is performed by a rotating barrel, thereby exposing the ends of the internal electrodes 6 to both ends of the ceramic body 4.

Thereafter, annealing is performed at 900 ° C. for 15 minutes, thereby inactivating the surface of the ceramic body 4.

Next, as shown in FIGS. 3 and 6, external electrodes 7 made of conductive paste are formed on both ends of the ceramic body 4 and on the upper, lower, front, and rear ends thereof.
Is made conductive.

The conductive paste contains Cu as a main component, and is baked at 800 ° C. in a neutral atmosphere to form the external electrodes 7.

The ceramic body 4 in the state shown in FIG.
Is stored together with the conductive balls 5 in the barrel 3 as shown in FIG.
To form

The plating solution 2 in the plating bath 1 for forming the plating film 8 is made of Ni chelate having a pH of 9 and having a pH of 9.
A plating solution is used, and the plating solution is heated to 50 ° C. in order to make the Ni chelate work effectively.

At this time, the current density of the cathode in the plating solution 2 is set so as to be as small as 0.55 A / dm ^2, and the plating time is extended as much as 45 minutes.

Thus, the plating film 8 having a thickness of about 2 μm is formed. The ceramic body 4 on which the plating film is formed as shown in FIG. 4 is lifted onto the plating tank 1, washed sufficiently with water, and drained. It is stored and immersed in.

In the next plating tank, a Sn plating solution having a pH of 8 and having a Sn chelate is placed at a temperature of 25 ° C. in order to make the Sn chelate act effectively. The current density of the cathode at that time was 0.33 A / dm.
^The plating time is as long as 60 minutes.

As a result, a Sn plating film 9 of 2 μm or more is formed on the plating film 8 as shown in FIGS. 5 and 6, and the size of the thus formed film is vertical. 0.6-0.8mm, width 0.8mm,
The length is 1.6 mm.

The ceramic electronic component formed in this way is called a chip thermistor, and is used in a portable telephone for temperature compensation for stabilizing the oscillation frequency.

[0031]

As described above, according to the present invention, a plating film is formed on an electrode surface provided on a ceramic body containing a transition metal oxide by using an alkaline solution having a pH higher than 7 as a plating solution. A method for plating a ceramic electronic component, wherein a transition metal is ionized and eluted into a plating solution due to a drastic decrease in a hydrogen ion concentration in the plating solution. There is no thinning of the elementary body, and the strength does not decrease.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of the ceramic body.

FIG. 3 is a sectional view of the ceramic body.

FIG. 4 is a cross-sectional view of the ceramic body.

FIG. 5 is a sectional view of the ceramic body.

FIG. 6 is a partially cutaway perspective view of the ceramic body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating tank 2 Plating solution 3 Barrel 4 Ceramic body 5 Conductive ball 6 Internal electrode 7 External electrode 8 Plating film 9 Plating film

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshiyuki Sato 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. No. (72) Inventor Yasutaka Baba 1006 Kadoma, Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (56) References JP 5-82386 (JP, A) JP 5-275240 (JP, A) JP-A-7-138782 (JP, A) JP-A-6-340994 (JP, A) JP-A-7-192927 (JP, A) JP-A-5-275273 (JP, A) JP-A-63-169015 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25D 5/54 C25D 7/00 H01G 4/10 H01G 4/12

Claims (8)

(57) [Claims] 1. A cell having an internal electrode and containing a transition metal oxide.
Laminate the chamfered body to part of the internal electrode.
Exposed outside the ceramic body of the
The body is annealed, and then the ceramic body is
As if electrically connected to the internal electrodes exposed to
An external electrode is provided on the surface of the
Alkaline solution with pH higher than 7 as plating solution on the surface
Of ceramic electronic components to form plating film using
The way. 2. The transition metal oxide is Mn, Ni, Co,
2. The method for plating a ceramic electronic component according to claim 1, comprising at least one oxide of Cu, Fe, and Cr. 3. The method for plating a ceramic electronic component according to claim 1, wherein the ceramic body is mainly composed of a transition metal oxide. 4. The plating method for a ceramic electronic component according to claim 3, wherein at least 80 at% of the ceramic body is composed of a transition metal oxide. 5. The electrode body according to claim 1, wherein the ceramic body is formed mainly of an oxide of Mn, and the electrode surface is plated using a plating solution having a pH higher than 7.6.
4. The method for plating a ceramic electronic component according to claim 1. 6. The method according to claim 1, wherein the plating is performed at a low current density of 1 A / dm ² or less. 7. An annealing temperature of 800 ° C. to 1100 ° C., after application of the external electrode, at a temperature lower than the annealing temperature,
The method for plating a ceramic electronic component according to claim 1 , wherein the external electrode is baked on a ceramic body. 8. The plating method for a ceramic electronic component according to claim 1 , wherein the external electrode is formed by applying a conductive paste containing Cu or Ag to the ceramic body and baking it in a neutral atmosphere or a reducing atmosphere. .