JP3077494B2 - Method of forming electrodes for feedthrough capacitors - 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 forming electrodes of a feedthrough capacitor used for noise suppression and the like, and more particularly, to easily adjust the peel strength between electroless plating layers constituting electrodes to an arbitrary value. The present invention relates to a method of forming electrodes of a feedthrough capacitor that can be performed.

[0002]

2. Description of the Related Art An electrode of a general feedthrough capacitor is shown in FIG.
As shown in FIG. 1, electroless plating layers 2a and 2a serving as base electrode layers are formed on the surface of the ceramic body 1 by electroless plating.
b, and a solder plating layer 3 or a tin plating layer is formed thereon by electroplating or the like.

[0003] In such an electrode of a feedthrough capacitor, the electroless plating layer is often in a multilayer structure of two layers or three or more layers as shown in the figure. This is because when soldering the electrodes of the feedthrough capacitor,
This is to prevent the element body from being broken by contraction stress due to heat during soldering. That is, by making the electroless plating layers provided in multiple layers easy to peel off, it is possible to prevent the shrinkage stress at the time of soldering from being applied to the element body.

Conventionally, there has been proposed a method of forming a silica layer between electroless plating layers in order to promote the separation between the electroless plating layers, that is, to facilitate the separation.

[0005]

However, the step of forming a layer such as a silica layer between the electroless plating layers for promoting the separation is a step different from the ordinary plating step, and requires a complicated operation. Furthermore, it is difficult to stably and reliably obtain a desired peel strength.

Further, since a layer for promoting peeling such as a silica layer is a kind of non-conductive layer, formation of such a layer may adversely affect characteristics (tan δ, etc.) as a capacitor. .

The present invention solves the above-mentioned conventional problems, and can easily and reliably adjust the peel strength between electroless plating layers to an arbitrary value without forming a layer for promoting peeling. An object of the present invention is to provide a method for forming electrodes of a feedthrough capacitor.

[0008]

According to a first aspect of the present invention, there is provided a method of forming an electrode of a feedthrough capacitor, comprising forming a plating layer on a surface of a ceramic body by electroless plating to form an electrode of the feedthrough capacitor. The plating layer formed by the electroless plating treatment includes a plurality of layers including at least a first plating layer on the surface of the ceramic body and a second plating layer on the first plating layer. In the method for forming an electrode of a feedthrough capacitor which is a plating layer, by controlling the content of a fluororesin which is eutectoid in the plating layer of the first layer, the plating layer of the first layer and the plating of the second layer and thereafter are controlled. It is characterized in that the peel strength between the layers is adjusted.

According to a second aspect of the present invention, there is provided the electrode forming method for the feedthrough capacitor, wherein the content of the fluorine resin co-deposited in the first plating layer is 1 to 15% by weight. And

According to a third aspect of the invention, there is provided a method for forming an electrode of a feedthrough capacitor, wherein the electroless plating layer is an electroless Ni plating layer.

Hereinafter, the present invention will be described in detail.

In the method of the present invention, for adjusting the content of the fluororesin co-deposited in the first electroless plating layer, for example, the fluororesin in the electroless plating solution for forming the first electroplating layer is used. What is necessary is just to increase or decrease the content.

That is, in the electroless plating, generally, the surface to be treated is immersed in a metal salt solution and subjected to a sensitizer treatment.
It is performed by immersing in an activator treatment by immersing in a catalyst solution, and then by immersing in an electroless plating solution. The content of the fluororesin in the formed electroless plating layer can be adjusted.

Thus, the higher the fluororesin content in the electroless plating solution, the higher the fluororesin content in the formed electroless plating layer, and the higher the fluororesin content in the electroless plating layer. The smaller the peel strength between the electroless plating layers of the first layer and the second layer, the smaller. Therefore, by adjusting the fluorine resin content in the electroless plating solution for forming the plating layer of the first layer according to the required peel strength, to form an electrode having a desired interlayer peel strength. Is made possible.

The method of the present invention is carried out in the same manner as in the prior art, except that the fluororesin content in the first electroless plating layer is controlled in accordance with the required peel strength between the electroless plating layers. There is no particular limitation on the type of electroless plating, the number of layers of electroless plating, the type of electroplating formed thereon, the thickness, and the like. ) Plating is desirable.

However, it is desirable that the uppermost electroless plating layer, that is, the electroless plating layer below the electroplating layer, is a fluorine resin-free electroless plating layer. This is because a fluorine resin-containing electroless plating layer may cause poor adhesion between the electroless plating layer and the electroplating layer.

The content of the fluororesin in the electroless plating solution for forming the first plating layer is preferably 0.7 to 10 g / l in order to obtain an electroless plating layer having an optimum peel strength. It is suitable. When an electroless plating solution having a fluororesin content of 0.7 to 10 g / l is used, generally, the content of fluorine co-deposited in the formed electroless plating layer is about 1 to 15% by weight.

The fluororesin contained in the electroless plating solution is polytetrafluoroethylene (PTF).
E) is most suitable. There are several other types of fluororesins, but they are not suitable because they contain chlorine and the like.

In the present invention, after forming the first plating layer, a heat treatment is performed at about 270 to 330 ° C. in order to increase the adhesion between the first plating layer and the element. Thereafter, it is preferable to form a second or subsequent plating layer.

In the present invention, when a plating layer having a two-layer structure is used, for example, the first plating layer is formed using an electroless Ni plating solution containing 0.7 to 10 g / l of a fluororesin. After the heat treatment, a second plating layer containing no fluorine resin is formed by the same treatment as the formation of the first plating layer except that a plating solution containing no fluorine resin is used. Thereafter, a solder plating layer may be formed by a conventional method such as electroplating. In addition,
It is preferable that the thickness of the first plating layer is about 1 to 3 μm, the thickness of the second plating layer is about 1 to 3 μm, and the thickness of the solder plating layer is about 5 to 10 μm.

[0021]

The anchor effect between the first and second electroless plating layers increases or decreases in accordance with the increase or decrease of the fluorine resin content in the first electroless plating layer. That is, when the fluororesin content of the first plating layer is small, the anchor effect is sufficiently obtained between the plating layers of the first layer and the second layer, the interlayer peel strength increases, and the peeling becomes difficult. On the other hand, if the content of the fluororesin in the first plating layer is large, the anchor effect is reduced, the interlayer peel strength is reduced, and the peeling is facilitated.

According to the present invention, only the processing conditions of the electroless plating at the time of forming the first layer plating layer, for example, the fluorine resin content in the electroless plating solution for forming the first layer plating layer, are changed. Easily without the need for a separate step of forming a layer for accelerating peeling as in the prior art, and without forming a layer that adversely affects the electrical characteristics of the feedthrough capacitor, such as a nonconductive layer. The peel strength between the electroless plating layers can be adjusted to an arbitrary value.

[0023]

The present invention will be described more specifically with reference to the following examples.

Example 1 According to the method of the present invention, electrodes of a feedthrough capacitor as shown in FIG. 1 were formed.

A predetermined amount of titanium oxide and barium carbonate were weighed, uniformly mixed and calcined. After finely pulverizing, an additive, a binder and the like were added, and a granulated powder was produced by a spray drying apparatus. This granulated powder was press-formed and fired to obtain a sintered body made of barium titanate (elementary body of a feedthrough capacitor).

After the surface of the body is roughened with an ammonium hydrogen fluoride solution, it is immersed in the order of a tin chloride solution (sensitizer), a palladium chloride solution (activator), and an electroless Ni plating solution containing a fluororesin (PTFE). And
First layer of fluororesin-containing electroless Ni plating layer (2 μm thick)
m) was formed. Here, the fluorine resin-containing electroless Ni plating solution has a fluorine resin content of 0.7 g / l,
Each of the four types of 3.3 g / l, 7 g / l, and 10 g / l was processed. Thereafter, in order to increase the adhesion between the formed first electroless Ni plating layer and the element body, heat treatment was performed at 300 ° C. in an electric furnace.

Next, the four types of samples prepared in the preceding step were immersed in a tin chloride solution (sensitizer), a palladium chloride solution (activator), and a fluorine resin-free electroless Ni plating solution, respectively. A second layer of a fluorine resin-free electroless Ni plating layer (thickness: 2 μm) was formed on the plating layer. Further, a solder plating layer (thickness: 10 μm) was formed thereon by electroplating to produce a feedthrough capacitor.

The relationship between the content of the fluororesin in the electroless Ni plating solution for forming the first plating layer and the content of the fluororesin in the formed electroless Ni plating layer of the first layer was determined. As shown in FIG. Further, the relationship between the content of the fluororesin in the electroless Ni plating layer containing the fluororesin and the peel strength between the first layer and the second layer was determined, and the results are shown in FIG.

As is apparent from FIG. 2, the higher the content of the fluororesin in the electroless Ni plating solution, the greater the content of the fluororesin in the formed electroless Ni plating layer. Also, as is clear from FIG. 3, the greater the fluorine resin content in the electroless Ni plating layer, the lower the delamination strength.

[0030]

As described in detail above, according to the electrode forming method of the feedthrough capacitor of the present invention, the peel strength between the electroless plating layers constituting the electrodes can be reduced without requiring any additional process. The formation can be easily controlled without forming a layer that adversely affects the characteristics of the feedthrough capacitor, and the electroless plating layer can be easily and stably formed so as to have a desired peel strength.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an electrode configuration of a feedthrough capacitor.

FIG. 2 shows the relationship between the fluororesin content in an electroless Ni plating solution for forming a first plating layer and the fluororesin content in a formed first electroless Ni plating layer in Example 1. It is a graph which shows a relationship.

FIG. 3 is a graph showing a relationship between a fluorine resin content in a fluorine resin-containing electroless Ni plating layer of a first layer and an interlayer peel strength between a first layer and a second layer in Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic body 2a, 2b Electroless plating layer 3 Solder plating layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-157016 (JP, A) JP-A-5-267092 (JP, A) JP-A 55-167637 (JP, U) Field (Int.Cl. ⁷ , DB name) H01G 4/00-4/40 H01G 13/00-13/06

Claims (3)

(57) [Claims] 1. A method for forming an electrode of a feedthrough capacitor by forming a plating layer on the surface of a ceramic body by electroless plating, wherein the plating layer formed by the electroless plating is at least a ceramic element. A method of forming an electrode of a feedthrough capacitor which is a plurality of plating layers including a first plating layer on a body surface and a second plating layer on the first plating layer, wherein the first layer By controlling the content of a fluorine resin that is eutectoid in the plating layer, the peel strength between the plating layer of the first layer and the plating layer of the second and subsequent layers is adjusted. A method for forming electrodes of a capacitor. 2. The method for forming an electrode according to claim 1, wherein
A method for forming an electrode of a feed-through capacitor, wherein the content of a fluorine resin co-deposited in a plating layer of the layer is 1 to 15% by weight. 3. The method for forming an electrode of a feedthrough capacitor according to claim 1, wherein the electroless plating layer is an electroless Ni plating layer.