JP2012077324A - Nickel plating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Ni plating liquid capable of reducing corrosion of a ceramic workpiece during plating.SOLUTION: In a preferred embodiment, the Ni plating liquid is used for forming a terminal electrode of a ceramic electronic part. The Ni plating liquid has a pH of ≥5.5 and contains at least one element chosen from the group consisting of Sr, Ba, Ca and Mg.

Description

  The present invention relates to a Ni plating solution, and more particularly to a Ni plating solution for forming a terminal electrode of a ceramic electronic component.

  As a ceramic electronic component, a structure in which a base electrode made of Ag, Cu, or the like, a terminal electrode including a Ni plating layer and a Sn plating layer is formed in order from the element body side on the end face of a ceramic body mainly formed of a ceramic material. Are known. In the terminal electrode having such a structure, the Ni plating layer is often formed by electric Ni plating using a Ni plating solution. As Ni plating solutions used for such electric Ni plating, those shown in the following Patent Documents 1 and 2 are known.

JP 2006-007731 A JP 2003-193284 A

  However, as a result of investigations by the present inventors, in the conventional Ni plating using the Ni plating solution, the Ni plating solution comes into contact with the element body during plating, which corrodes the surface portion of the element body. It has been found that inconvenience may occur. When corrosion occurs on the surface of the element body, the electrical characteristics of the ceramic electronic component tend to be easily deteriorated, for example, an insulation resistance (IR) defect is likely to occur.

  Then, this invention is made | formed in view of such a situation, and it aims at providing the Ni plating liquid which can reduce the corrosion of the ceramic body during plating.

  In order to achieve the above object, the Ni plating solution of the present invention is a Ni plating solution for forming a terminal electrode of a ceramic electronic component and has a pH of 5.5 or more, and Sr, Ba, Ca and Mg. It contains at least one element selected from the group consisting of:

  In electric Ni plating, as a technique for suppressing corrosion of a ceramic body that occurs during plating, a technique for raising the pH is first known. For example, in the case of normal Ni plating such as a watt bath or a sulfamic acid Ni plating bath, pH adjustment is performed using Ni carbonate. However, since Ni carbonate is a weak alkali, the practical upper limit of the pH is 5 to 5.3, but in this pH region, corrosion during plating of the ceramic body is still large, and IR failure after plating is poor. There is a tendency that it cannot be sufficiently suppressed. In addition, when the pH is raised to near the upper limit, it may be necessary to remove excess Ni carbonate by filtration. Furthermore, there is a problem in the stability of the plating solution, for example, the amount of carbonic acid in the plating solution increases and the plating solution becomes unstable, and the plating solution may decompose immediately after energization.

  Therefore, there is a method of adjusting the pH with an alkali metal hydroxide such as NaOH instead of Ni carbonate. In this case, although the pH easily rises, the surface corrosion of the ceramic body during plating is still unsatisfactory. There is a big tendency. This is because alkali metal has a high solubility in Ni plating solution, and during electro Ni plating, alkali metal cations concentrate on the cathode to generate strong alkali, which corrodes the surface portion of the element body. It is thought that this is because. Furthermore, it is conceivable to adjust the pH with a hydroxide containing ammonia or an ammonium salt, but in this case as well, corrosion during plating is increased by the same mechanism as that of an alkali metal hydroxide. In particular, when these are used, since ammonia is a chelating agent, elution occurs due to bonding with the metal oxide on the surface of the ceramic body, even just immersing the ceramic body in the plating solution without energization, This is not preferable because the surface corrosion is increased. Therefore, the preferable content in the plating solution of the compound containing ammonia and ammonium salt is usually 0.5 mol / L or less. As described above, in addition to having a pH high enough to prevent corrosion of the ceramic body during plating, it has been extremely difficult to suppress corrosion due to factors other than pH. It was.

  On the other hand, the Ni plating solution of the present invention contains at least one element selected from the group consisting of Sr, Ba, Ca and Mg. The Ni plating solution containing these elements can easily realize a pH of 5.5 or higher, and can satisfactorily suppress corrosion of the ceramic body after plating. This is because cations consisting of Sr, Ba, Ca, and Mg are concentrated on the cathode in the same manner as in the case of alkali metals, but the solubility in the Ni plating solution is small, so that the upper limit is higher than the solubility. This is considered to be because the concentration of the cation does not occur and the increase in pH around the cathode is suppressed. Therefore, according to the Ni plating solution of the present invention, corrosion of the element body can be reduced even when the Ni plating layer is formed on the terminal electrode of the ceramic electronic component by electric Ni plating. In particular, Sr or Ba is preferable among at least one element selected from the group consisting of Sr, Ba, Ca and Mg.

  The Ni plating solution of the present invention preferably has an alkali metal element content of 0.08 mol / L or less. When the content of the alkali metal element is not more than such a specific value, it is possible to further reduce the corrosion of the element body that occurs during the electric Ni plating.

  The Ni plating solution of the present invention is more preferably a chloride bath (a bath in which the Ni ion source is Ni chloride). Thus, when a chloride bath containing only Ni chloride is used as the Ni ion source, it is possible to further improve the plating rate while further suppressing corrosion of the element body. In addition, it is thought that the improvement of a plating rate is acquired when the electroconductivity of a plating solution goes up in the case of a chloride bath.

  Furthermore, it is preferable that the ceramic electronic component to which the Ni plating solution of the present invention is applied includes a ceramic body containing Zn and a terminal electrode formed at an end of the ceramic body. In particular, the ceramic body containing Zn tends to be eluted into the plating solution during plating, and therefore tends to be corroded during electric Ni plating. Since the Ni plating solution of the present invention is extremely unlikely to cause corrosion of the ceramic body, even when such a ceramic body containing Zn is used, a sufficient plating rate can be obtained while suppressing corrosion. Is possible.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide Ni plating solution which can reduce the corrosion of the ceramic body during plating.

It is a figure which shows typically the cross-sectional structure of a ceramic electronic component provided with the terminal electrode by which Ni plating layer was formed with Ni plating solution of suitable embodiment. 6 is a graph showing values of corrosion distances with respect to addition amounts of various alkali metal chlorides in Experimental Example 5.

  Preferred embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[Ni plating solution]
First, the Ni plating solution according to a preferred embodiment will be described.

  The Ni plating solution of this embodiment is a Ni plating solution containing Ni, has a pH of 5.5 or higher, and contains at least one element selected from the group consisting of Sr, Ba, Ca, and Mg.

  As the Ni plating solution, an Ni source containing, for example, nickel chloride, nickel sulfate, nickel sulfamate, nickel bromide, or nickel acetate can be applied. For example, a chloride bath containing only nickel chloride as a Ni source (total chloride bath), a watt bath containing a combination of nickel sulfate and nickel chloride, and a nickel sulfamate bath containing a combination of nickel sulfamate and nickel chloride are applicable. can do. Among them, the chloride bath tends to be preferable because a high plating rate can be obtained while suppressing the corrosion of the ceramic body.

  The Ni plating solution contains at least one element selected from the group consisting of Sr, Ba, Ca, and Mg in a metal or ion state. These elements are added to the Ni plating solution in the form of hydroxide, halide, sulfate or the like. However, when these elements are contained as halides, if they are contained as chlorides, the effect of suppressing corrosion tends to be obtained very well as compared with inclusion in the form of bromide or iodide. It is particularly preferable that at least one element selected from the group consisting of Sr, Ba, Ca and Mg is added as a hydroxide among the above-mentioned elements. By being contained as a hydroxide, it becomes easy to adjust the pH of the Ni plating solution to 5.5 or more, and there is a tendency that the effect of preventing corrosion by alkali metal in principle can be obtained better.

  The Ni plating solution preferably contains Sr or Ba as at least one element selected from the group consisting of Sr, Ba, Ca and Mg. The Ni plating solution containing these elements is easy to prepare and tends to further reduce the corrosion of the ceramic body.

  The content of at least one element selected from the group consisting of Sr, Ba, Ca and Mg in the Ni plating solution is preferably 0.0003 mol / L or more with respect to the entire Ni plating solution, and 0.001 mol. / L or more is more preferable, and 0.01 mol / L or more is more preferable. The more suitable the content of these elements is, the more the Ni plating solution has a good pH, but can further reduce the corrosion of the ceramic body during plating. However, if the content of these elements is too large, a large amount of Sr, Ba, Ca and Mg is co-deposited in the film formed by Ni plating, and this part is dissolved during the moisture resistance test, thereby moisture is absorbed. The upper limit of the content is preferably set to 1 mol / L because there is a possibility of inconvenience that the connection resistance increases due to intrusion into the joint between the internal electrode and the base electrode.

  The pH of the Ni plating solution is 5.5 or more, preferably 5.5 to 6, and more preferably 5.6 to 5.9. The more suitable PH, the better the plating bath stability can be obtained while suppressing the corrosion of the ceramic body.

  In the Ni plating solution, the content of the alkali metal element is preferably 0.4 mol / L or less, more preferably 0.2 mol / L, more preferably 0.08 mol / L with respect to the entire Ni plating solution. More preferably, The more the alkali metal content is in such a suitable range, the better the corrosion of the ceramic body during plating can be reduced. In particular, the Ni plating solution can easily adjust the pH by containing an alkali metal hydroxide such as NaOH. It is possible to effectively prevent the ceramic body from being corroded by adjusting the content to be within the above-mentioned preferable range.

  From the viewpoint of preventing the corrosion of the ceramic body, the Ni plating solution does not contain alkali metal (alkali metal hydroxide), that is, even if the content of alkali metal is 0 mol / L. Good. However, in that case, depending on the combination with other components, it may be difficult to obtain a good pH of the Ni plating solution. Therefore, from the viewpoint of obtaining a good pH, an alkali metal hydroxide may be added within a range in which the above-described suitable conditions for the alkali metal content are satisfied. In particular, when a hydroxide of at least one element selected from the group consisting of Sr, Ba, Ca and Mg and a hydroxide of an alkali metal are combined in the range of the above preferable conditions, a good pH is obtained. In addition to being easily obtained, corrosion of the ceramic body may be sufficiently prevented.

  In addition to the components described above, the Ni plating solution includes known components used in the Ni plating solution, such as nickel chloride, nickel bromide, boric acid, and other buffering agents, and alkali metal hydroxides. A pH adjusting agent (for example, nickel carbonate), a brightener, a conductive agent such as sodium sulfate, and the like may be further included.

[Ceramic electronic components]
Next, an example of a ceramic electronic component in which the Ni plating layer of the terminal electrode is formed using the Ni plating solution of the above-described embodiment will be described. FIG. 1 is a diagram schematically showing a cross-sectional configuration of a ceramic electronic component according to a preferred embodiment. A ceramic electronic component 100 shown in FIG. 1 includes a ceramic body 3 and terminal electrodes 7 provided at both ends of the ceramic body.

  The ceramic body 3 includes a plurality of (here, three) ceramic layers 1 made of a ceramic material, and internal electrodes 2 (internal electrodes 2a and 2b) provided between the ceramic layers 1. In other words, the ceramic body 3 is composed of a laminated body in which the ceramic layers 1 and the internal electrodes 2 are alternately laminated. In the ceramic body 3, the internal electrodes 2 a and 2 b are provided (extracted) so that one end of each of the internal electrodes 2 a and 2 b is exposed to different opposing end faces of the ceramic body 3. And connected to the terminal electrode 7 (base electrode 4).

  The ceramic material constituting the ceramic layer 1 is selected according to the required characteristics depending on the type of the ceramic electronic component 100. For example, according to the use of the ceramic electronic component 100 such as a capacitor, a varistor, or a thermistor, a known dielectric ceramic, semiconductor ceramic, magnetic ceramic, or the like can be appropriately selected and applied as the ceramic material.

  Examples of the ceramic material include those containing Zn. That is, the ceramic body 3 may contain Zn. For example, semiconductor ceramics include those containing a compound (oxide or the like) containing Zn as a main component, and dielectric ceramics include those containing Zn as a sintering aid. In particular, in the case of dielectric ceramics, thinning of the ceramic layer is progressing in order to reduce the size of electronic parts using the dielectric ceramic, and therefore, it is particularly preferable to contain Zn from the viewpoint of further lowering the sintering temperature. .

  In addition, the element body using the ceramic material containing Zn tends to have poor chemical resistance, and tends to be deteriorated, such as partial dissolution of the ceramic material in plating or the like when forming the terminal electrode. is there. However, since the ceramic electronic component 100 of the present embodiment has the Ni layer 5 formed using the Ni plating solution of the present embodiment, as will be described later, the corrosion of the element body after the Ni plating is small. .

More specifically, examples of semiconductor ceramics containing Zn include those having a composition containing ZnO as a main component. Dielectric ceramics include barium titanate (BaTiO ₃ ) as a main component, and subcomponents ( What further contains Zn as a sintering aid) is mentioned.

  The constituent material of the internal electrodes 2a and 2b is not particularly limited as long as it can reliably perform ohmic junction with the ceramic layer 1. For example, single metals of Ag, Pd, Ni, Cu, and Al, and materials (alloys, compounds, etc.) containing these as main components can be mentioned. When the main component of the ceramic layer 1 is barium titanate, for example, Ni, Cu, Ag / Pd alloy, Ag / Zn alloy, Ag / Al alloy, or the like is preferably used as the constituent material of the internal electrodes 2a and 2b.

  The pair of terminal electrodes 7 are provided on the end surfaces of the ceramic body 3 where the internal electrodes 2a and 2b are exposed. Each terminal electrode 7 includes a base electrode 4, a Ni layer 5, and a Sn layer 6 in order from the ceramic body 3 side.

  The base electrode 4 is provided mainly for the purpose of reducing the connection resistance with the internal electrodes 2a and 2b. From this viewpoint, it is necessary to be made of a metal or alloy that forms an ohmic junction with the internal electrodes 2a and 2b.

  More specifically, when the internal electrodes 2a and 2b are made of Ni, the material of the base electrode 4 is preferably Cu, an Ag / Zn alloy, an Ag / Al alloy, or the like. When the internal electrodes 2a and 2b are made of Ni, Ni can also be applied as the material for the base electrode 4. However, in that case, since it is necessary to fire at a high temperature in a reducing atmosphere, cracks are generated due to thermal stress generated between the ceramic body 3 and the ceramic body 3. It is preferred to note that the properties change due to reduction during firing.

  The Ni layer 5 is a layer mainly composed of Ni, and is a Ni plating layer formed using the Ni plating solution of the above-described embodiment. Here, “a layer mainly composed of Ni” means that 98% by mass or more of the layer is represented by Ni, and includes a case where it is composed only of Ni except for impurities inevitably mixed. . The Sn layer 6 described later is also a layer mainly composed of Sn, and its definition is the same as in the case of the Ni layer.

  Since the Ni layer 5 is formed by the Ni plating solution of the above-described embodiment, at least one element selected from the group consisting of Sr, Ba, Ca, and Mg is contained in the layer of a simple metal, an alloy, or a compound. Include in state. The content of these elements in the Ni layer 5 is preferably 5 to 2000 ppm, and more preferably 10 to 500 ppm. When these elements are contained in the Ni layer 5, the penetration of moisture and the like in the terminal electrode 7 is prevented, and the corrosion resistance of the ceramic electronic component 100 tends to be improved.

  The Sn layer 6 has a function of improving wettability with respect to solder. Since the Sn layer 6 is provided on the surface of the terminal electrode 7, the terminal electrode 7 can be soldered satisfactorily. Further, the Ni layer 5 functions as a barrier metal that prevents diffusion of metal between the base electrode 4 and the Sn layer 6 due to heat at the time of soldering, for example. By providing the Ni layer 5 between the base electrode 4 and the Sn layer 6, it is possible to suppress poor soldering and long-term reliability that are likely to occur due to the mutual diffusion of the metal in the terminal electrode 7. Can do.

  The Sn layer 6 is also preferably an Sn plating layer formed by Sn plating. By plating, the Sn layer 6 has a dense structure, and the corrosion resistance of the ceramic electronic component 100 can be improved. From the viewpoint of improving the corrosion resistance, the Sn layer 6 is also made of at least one element selected from the group consisting of Sr, Ba, Ca and Mg, preferably 5 to 2000 ppm, more preferably 10 like the Ni layer 5. It is preferable to contain -500 ppm.

  In the terminal electrode 7, the preferred thickness of each layer is as follows. That is, the thickness of the base electrode 4 is preferably 5 to 50 μm, and more preferably 10 to 40 μm. Moreover, the thickness of the Ni layer 5 is preferably 1 to 5 μm, and more preferably 2 to 3 μm. Furthermore, the thickness of the Sn layer 6 is preferably 2 to 10 μm, and more preferably 3 to 6 μm.

  Next, a preferred embodiment of a method for manufacturing the ceramic electronic component 100 having the above-described configuration will be described.

  First, the ceramic body 3 is formed by a known method. That is, a pattern of the internal electrodes 2a and 2b is formed on the surface of the ceramic layer green sheet for forming the ceramic layer 1 by screen printing of a conductive paste or the like. As a constituent material of the green sheet, a material capable of forming a desired ceramic layer 1 after firing may be applied. Then, after laminating the ceramic layer green sheet having the internal electrode pattern formed of the conductive paste on the surface so as to obtain the laminated structure of the ceramic body 3, the ceramic body 3 is obtained by firing. .

  Next, the base electrode 4 is formed on the end face where the internal electrodes 2a and 2b of the ceramic body 3 are exposed. The base electrode 4 can be formed by applying a conductive paste to the end face of the ceramic body 3 and firing it (sintering method). Examples of the conductive paste include those containing metal powder, organic vehicle (binder) and glass powder (frit) constituting the base electrode 4. Moreover, you may add additives, such as a viscosity modifier, an inorganic binder, and an oxidizing agent, to an electrically conductive paste as needed. By baking, the organic vehicle is volatilized, and the base electrode 4 containing a metal and a glass component is formed.

  Then, the Ni layer 5 is formed on the surface of the base electrode 4 by performing electric Ni plating using the Ni plating solution of the above-described embodiment. The temperature of the Ni plating solution when performing electric Ni plating is preferably 10 to 60 ° C, and more preferably 15 to 30 ° C.

  Next, the Sn layer 6 is formed on the surface of the Ni layer 5 by electric Sn plating. As the Sn plating solution used at this time, a known Sn plating solution can be applied. For example, methanesulfonic acid Sn may be used as a Sn ion source, sodium gluconate as a chelating agent, and sodium methanesulfonate as a conductive salt. The Sn plating solution may contain a component for adjusting pH (alkali metal hydroxide, ammonia, etc.), a brightener, and the like, if necessary. The concentration of Sn ions in the Sn plating solution is preferably 0.05 to 0.2 mol / L because the Sn layer 6 can be formed satisfactorily.

  The Sn plating solution may contain at least one element selected from the group consisting of Sr, Ba, Ca and Mg in the form of a metal, a compound or an ion. By containing these components in the Sn plating solution, the corrosion of the ceramic body 3 tends to be reduced even during the electric Sn plating. And the Sn layer 6 containing these elements comes to have a dense structure, and may improve the corrosion resistance of the ceramic electronic component 100 in some cases. When these elements are contained in the Sn plating solution, the concentration of ions of these elements is preferably 0.005 to 0.1 mol / L, and 0.01 to 0.05 mol / L. It is more preferable that

  In the plating for forming the Sn layer 6, for example, the pH of the Sn plating solution is preferably 4 to 8, and more preferably 6 to 7.8. The temperature of the Sn plating solution is preferably 10 to 40 ° C, and more preferably 15 to 30 ° C.

  After the Ni layer 5 and the Sn layer 6 are formed by the plating, a predetermined heat treatment may be performed on these layers. For example, by performing a heat treatment at 150 ° C. for about 30 minutes, the constituent components may diffuse between the Ni layer 5 and the Sn layer 6 and the adhesion between the two layers may be improved.

  The ceramic electronic component 100 is obtained by the manufacturing method as described above. In this manufacturing method, the Ni plating solution of the preferred embodiment described above is used when the Ni layer 5 in the terminal electrode 7 is formed. The Ni plating solution contains at least one element selected from the group consisting of Sr, Ba, Ca, and Mg, so that the amount of alkali metal that has conventionally been a cause of corrosion of the ceramic body 3 is small. In addition, it can have a pH (pH 5.5 or more) that can sufficiently inhibit the corrosion of the ceramic body during plating without adding an alkali metal.

  Therefore, during the electric Ni plating for forming the Ni layer 5, the corrosion of the ceramic body 3 by the Ni plating solution can be greatly reduced. As a result, it is possible to obtain the ceramic electronic component 100 with little deterioration in electrical characteristics such as IR failure.

  As described above, the Ni plating solution according to the preferred embodiment of the present invention and the method for manufacturing the ceramic electronic component using the same have been described. However, the present invention is not necessarily limited to the above-described embodiment, and the present invention is not limited thereto. Any change can be made without departing from the scope of the present invention.

  For example, in the embodiment described above, in the manufacture of the terminal electrode 7, the Ni layer 5 is formed on the surface of the base electrode 4 by electric Ni plating. However, the present invention is not limited to this. 3 may be directly applied to the surface of the electrode 3 or may be applied to the layer of the base electrode 4 or more. Further, the Sn layer 6 is not necessarily formed by plating, and may be formed by other methods.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not necessarily limited to these Examples.

[Experimental Example 1]
(Production of ceramic capacitors)
First, it has a composition containing barium titanate as a main component and 2% of ZnO added, on the end face of the ceramic body having an outer dimension of 1.6 × 0.8 × 0.8 (mm). Then, a copper paste was applied and baked to form a base electrode, and a plurality of chip capacitors in a state before the Ni layer and the Sn layer were formed were prepared. The insulation resistance (IR) of all chip capacitors was measured, and those with an IR of 10 ⁸ Ω or less were excluded.

  On the surface of the base electrode of the obtained chip capacitor, a Ni layer having a thickness of 2 μm and a Sn layer having a thickness of 4 μm are formed by sequentially performing Ni plating and Sn plating by an electric barrel plating method, respectively. (Ceramic electronic component) was obtained. The current value in electric barrel plating was adjusted so that a film thickness of 2 μm was obtained in 2 hours in the case of Ni plating and 5 μm in 2 hours in the case of Sn plating.

  Under the present circumstances, Ni plating and Sn plating were performed on the conditions using the following Ni plating solution and Sn plating solution. In Experimental Example 1, as shown in Table 1, Ni plating was performed under a plurality of conditions using Ni plating solutions with different amounts of strontium hydroxide added, and various ceramic capacitors were produced.

(1) Ni plating solution nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Strontium hydroxide octahydrate: addition amount shown in Table 1 pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(2) Sn plating solution methanesulfonic acid Sn: 0.1 mol / L
Sodium gluconate: 0.4 mol / L
Sodium methanesulfonate: 0.3 mol / L
Brightener: appropriate amount pH: 6.0 (adjusted with Na hydroxide)
Liquid temperature: 25 ° C

(Characteristic evaluation)
(1) Corrosion distance The corrosion distance of the ceramic body portion of each of the chip capacitors obtained above was examined. The corrosion distance means the thickness from the surface of the ceramic body of the portion of the ceramic body that is observed to be corroded by observing a cross section of the ceramic body with a scanning electron microscope. The obtained results are shown in Table 1. The corrosion distance was an average value of 10 samples subjected to Ni plating under the same conditions.

(2) Measurement of IR defect rate after plating Further, IR was measured for various chip capacitors, and those that were 10 ⁸ Ω or less were regarded as defective. And the ratio (IR defect rate (%) after plating) of what was unsatisfactory among 100 samples which performed Ni plating on the same conditions was calculated | required. The obtained results are shown in Table 1.

(3) Measurement of IR failure rate after moisture resistance load test Further, the moisture resistance load test was performed on the various chip capacitors obtained above under the condition of applying a voltage of 6V for 1000 hours in an atmosphere of 85 ° C. and 85% RH. Then, the IR of the chip capacitor after the test was measured, and those that were similarly 10 ⁸ Ω or less were regarded as defective. And the ratio (IR defect rate (%) after a moisture-proof load test) of what was unsatisfactory among 100 samples which performed Ni plating on the same conditions was calculated | required. The obtained results are shown in Table 1.

  As shown in Table 1, when the Ni plating solution contains Sr, the corrosion distance was smaller and the IR failure rate after plating and after the moisture resistance load test was smaller than when Sr was not included. It was confirmed that the ceramic body was hardly corroded, and that the ceramic body was hardly corroded in the moisture resistance load test.

[Experiment 2]
(Production of ceramic capacitors)
A ceramic capacitor was obtained in the same manner as in Example 1 except that the following plating solution containing barium hydroxide instead of strontium hydroxide was used as the Ni plating solution. That is, in Experimental Example 2, as shown in Table 2, various ceramic capacitors were prepared using Ni plating solutions with different amounts of barium hydroxide added.

(1) Ni plating solution nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Barium hydroxide octahydrate: addition amount shown in Table 2 pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(Characteristic evaluation)
For the various ceramic capacitors obtained, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test were determined in the same manner as in Experimental Example 1. The obtained results are shown in Table 2.

  From Table 2, it was confirmed that when the Ni plating solution contains Ba, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test can be reduced satisfactorily. Further, it has been found that the effect is good when the amount of barium hydroxide added is 0.001 or more.

[Experiment 3]
(Production of ceramic capacitors)
A ceramic capacitor was obtained in the same manner as in Example 1 except that the following plating solution containing calcium hydroxide was used instead of strontium hydroxide as the Ni plating solution. That is, in Experimental Example 3, as shown in Table 3, various ceramic capacitors were manufactured using Ni plating solutions with different amounts of calcium hydroxide added.

(1) Ni plating solution nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Calcium hydroxide octahydrate: added amount shown in Table 3 pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(Characteristic evaluation)
For the various ceramic capacitors obtained, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test were determined in the same manner as in Experimental Example 1. The obtained results are shown in Table 3.

From Table 3, it was confirmed that when the Ni plating solution contains Ca, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test can be reduced satisfactorily. The effect was found to be good when the amount of calcium hydroxide added was 0.001 moL / L or more.
[Experimental Example 4]
(Production of ceramic capacitors)
A ceramic capacitor was obtained in the same manner as in Example 1 except that the following plating solution containing magnesium hydroxide was used instead of strontium hydroxide as the Ni plating solution. That is, in Experimental Example 4, as shown in Table 4, various ceramic capacitors were manufactured using Ni plating solutions having different amounts of magnesium hydroxide.

(1) Ni plating solution nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Magnesium hydroxide octahydrate: added amount shown in Table 4 pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(Characteristic evaluation)
For the various ceramic capacitors obtained, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test were determined in the same manner as in Experimental Example 1. Table 4 shows the obtained results.

  From Table 4, it was confirmed that when the Ni plating solution contains Mg, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test can be reduced satisfactorily. Further, it has been found that the effect is good when the amount of magnesium hydroxide added is 0.001 or more.

[Experimental Example 5]
(Production of ceramic capacitors)
A ceramic capacitor was obtained in the same manner as in Example 1 except that the following was used as the Ni plating solution. That is, in Experimental Example 5, various ceramic capacitors were manufactured using Ni plating solutions having different pH values as shown in Table 5.

(1) Ni plating solution nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Strontium hydroxide octahydrate: 0.01 mol / L
pH: pH shown in Table 5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(Characteristic evaluation)
For the various ceramic capacitors obtained, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test were determined in the same manner as in Experimental Example 1. The results obtained are shown in Table 5.

  From Table 5, it was confirmed that when the pH of the Ni plating solution is 5.5 or more, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test can be reduced satisfactorily.

[Experimental Example 6]
(Production of ceramic capacitors)
A ceramic capacitor was obtained in the same manner as in Example 1 except that the following Ni plating solutions A, B, and C were used as the Ni plating solution. That is, in Experimental Example 6, various ceramic capacitors were manufactured using Ni plating solutions having different components added as Ni sources.

(1) Ni plating solution A
Nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Strontium hydroxide octahydrate: 0.01 mol / L
pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(2) Ni plating solution B
Nickel chloride hexahydrate: 0.5 mol / L
Boric acid: 0.3 mol / L
Strontium hydroxide octahydrate: 0.01 mol / L
pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(3) Ni plating solution C
Nickel sulfamate tetrahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Strontium hydroxide octahydrate: 0.01 mol / L
pH: 5.5
pH adjuster: nickel carbonate solution temperature: 25 ° C

(Characteristic evaluation)
For the various ceramic capacitors obtained, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test were determined in the same manner as in Experimental Example 1. The results obtained are shown in Table 6.

  From Table 6, it was confirmed that when the Ni plating solution used was only a chloride (chloride bath), the corrosion distance was particularly small and the corrosion of the ceramic body could be suppressed.

[Experimental Example 7]
A ceramic capacitor was obtained in the same manner as in Example 1 except that the following plating solution in which an alkali metal chloride was added to the Ni plating solution was used. That is, in Experimental Example 7, as shown in Table 7, various ceramic capacitors were prepared using Ni plating solutions having different types and concentrations of alkali metal chlorides.

(1) Ni plating solution nickel sulfate hexahydrate: 0.4 mol / L
Nickel chloride hexahydrate: 0.1 mol / L
Boric acid: 0.3 mol / L
Strontium hydroxide octahydrate: 0.01 mol / L
Alkali metal chlorides: types shown in Table 7 and added amounts pH: 5.5
Liquid temperature: 25 ° C

(Characteristic evaluation)
For the various ceramic capacitors obtained, the corrosion distance, the IR failure rate after plating, and the IR failure rate after the moisture resistance load test were determined in the same manner as in Experimental Example 1. The obtained results are shown in Table 7 and FIG.

  From Table 7 and FIG. 2, when there was too much content of the alkali metal in Ni plating solution, it was confirmed that a corrosion distance will become large and there exists a tendency for the IR defect rate after a plating and a moisture-proof load test to increase.

DESCRIPTION OF SYMBOLS 1 ... Ceramic layer, 2a, 2b ... Internal electrode, 3 ... Ceramic body, 4 ... Base electrode, 5 ... Ni layer, 6 ... Sn layer, 7 ... Terminal electrode, 100 ... Ceramic electronic component.

Claims (5)

Ni plating solution for forming terminal electrodes of ceramic electronic components,
A Ni plating solution characterized by having a pH of 5.5 or higher and containing at least one element selected from the group consisting of Sr, Ba, Ca and Mg. The Ni plating solution according to claim 1, wherein the content of the alkali metal element is 0.08 mol / L or less. The Ni plating solution according to claim 1, wherein the Ni plating solution is a chloride bath. The Ni plating solution according to claim 1, wherein the element is Sr or Ba. The said ceramic electronic component is equipped with the ceramic body containing Zn, and the said terminal electrode formed in the edge part of the said ceramic body, The any one of Claims 1-4 characterized by the above-mentioned. Ni plating solution as described in 4.

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