JP2012036435A - Electrolytic tin plating solution, and method for manufacturing ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic tin plating solution that controls corrosion of a ceramic electronic component body, which is caused by plating, and achieves stable plating, and to provide a method for manufacturing a ceramic electronic component using the electrolytic tin plating solution.SOLUTION: The electrolytic tin plating solution for the ceramic electronic component contains stannous ion and a chelating agent, and whose pH is controlled between 6-9, and whose value of the relation (molar concentration of the chelate agent)/(molar concentration of stannous ion) is controlled higher than 2.4 and 4.5 or less.

Description

  The present invention relates to an electrotin plating solution suitably used for ceramic electronic components and a method for producing a ceramic electronic component using the plating solution.

  Electrotin (Sn) plating is widely used in the process of forming terminal electrodes of ceramic electronic parts made of thermistors, capacitors, inductors, LTCC (Low Temperature Co-fired Ceramics), varistors, and their composites. For example, a conductive paste such as silver or copper is applied to the surface of a ceramic electronic component having an internal electrode, and after baking it to form a base electrode, a nickel layer is selectively formed on the surface of the base electrode by electric barrel plating. And a tin layer is formed continuously and a terminal electrode is comprised. For the electroplating of the tin layer, a neutral tin plating solution having a pH of 4 to 9 is often used.

  Conventionally, there has been a problem that the electrical characteristics of a ceramic electronic component after plating are deteriorated as compared with the electrical characteristics before plating. One of the reasons is that the plating solution can enter the inside of the element body through a large number of pores present in the element body mainly made of ceramics and corrode the element body. From such a viewpoint, as shown in Patent Document 1, a method has been proposed in which the viscosity of the plating solution is increased to suppress the penetration of the plating solution into the pores.

Japanese Patent Publication No. 7-23554

  However, according to the inventor's research, it has been found that the method of simply adjusting the viscosity of the plating solution cannot sufficiently suppress the corrosion of the element body. For this reason, a plating solution that can sufficiently suppress the corrosion of the element body and prevent the deterioration of the electrical characteristics of the ceramic electronic component due to plating is desired.

  Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to suppress corrosion of the ceramic electronic component body due to plating and to enable stable plating, and the electrotin plating. An object of the present invention is to provide a method for manufacturing a ceramic electronic component using a liquid.

  In order to achieve the above object, the electrotin plating solution of the present invention is an electrotin plating solution for ceramic electronic components, containing tin ions and a chelating agent, having a pH of 6 or more and 9 or less, and the molarity of the chelating agent. The value of the ratio of concentration / molar concentration of tin ions (both molar concentration with respect to the entire electrotin plating solution) is greater than 2.4 and not greater than 4.5.

  When the pH exceeds 9, or when the ratio of the molar concentration of the chelating agent / the molar concentration of tin ions is 2.4 or less, precipitation occurs during standing or energization, and the composition of the plating solution fluctuates and is stable. Tends to be difficult. Further, when the pH is less than 6, or when the ratio of the chelating agent molar concentration / tin ion molar concentration exceeds 4.5, the ceramic electronic component body tends to corrode. Therefore, by adjusting the pH value of the electrotin plating solution and the ratio of the molar concentration of the chelating agent / the molar concentration of the tin ion within the above-described ranges, corrosion of the ceramic electronic component body is suppressed and stable plating is achieved. Can be done.

  Preferably, sulfamate ions derived from a tin ion supply substance or other additives are contained, and the sulfamate ion concentration relative to the entire electrotin plating solution is less than 0.5 mol / L. When the concentration of the sulfamate ions is 0.5 mol / L or more, precipitation is likely to occur when left standing or energized, and the composition of the plating solution fluctuates due to this, making stable plating difficult. There is a tendency.

  Preferably, the chelating agent concentration with respect to the entire electrotin plating solution is 0.3 mol / L or less. When the chelating agent concentration exceeds 0.3 mol / L, the body of the ceramic electronic component tends to corrode. Examples of chelating agents include gluconic acid, citric acid, pyrophosphoric acid and their salts, but gluconic acid and its salts have a stable plating solution or can form a tin plating film with good solderability. Yes, it is preferable.

  Preferably, ammonia or ammonium ions are further included, and the concentration of ammonia and ammonium ions in the electrotin plating solution is 0.3 mol / L or less. When the concentrations of ammonia and ammonium ions exceed 0.3 mol / L, the ceramic electronic component body tends to corrode.

  Preferably, a conductive agent that is an alkali or alkaline earth metal salt is further included, and the value of the ratio of the molar concentration of the conductive agent to the molar concentration of tin ions with respect to the entire electrotin plating solution is 2 or more and less than 12. If the value of the ratio of the molar concentration of the conductive agent / the molar concentration of tin ions is smaller than 2, when soldering is performed on the plating film, soldering defects tend to occur. Further, when the value of the molar concentration of the conductive agent / the molar concentration of tin ions is 12 or more, precipitation occurs when left standing or energization, the composition of the plating solution is likely to fluctuate, and as a result, stable plating becomes difficult. There is a tendency. Examples of the conductive agent include methanesulfonic acid, sulfuric acid, hydrochloric acid, and salts thereof, and methanesulfonic acid and salts thereof are preferable because precipitation hardly occurs and the plating solution is stable.

  Preferably, the temperature of the electrotin plating solution is greater than 5 ° C and less than 35 ° C. When the temperature of the electrotin plating solution is 5 ° C. or lower, precipitation occurs during standing or energization, the composition of the plating solution varies, and stable plating tends to be difficult. When the temperature of the electrotin plating solution is 35 ° C. or higher, poor soldering tends to occur when soldering is performed on the plating film.

  Furthermore, in order to achieve the above object, the method for producing a ceramic electronic component according to the present invention is a method that can be suitably carried out using the electrotin plating solution according to the present invention. A step of forming a tin layer using a plating solution, in which a tin ion and a chelating agent are included, the pH is 6 or more and 9 or less, and the molar concentration of the chelating agent in tin electroplating / the molar concentration of tin ions An electrotin plating solution having a ratio value greater than 2.4 and not greater than 4.5 is used.

  In particular, when the ceramic body containing zinc element is used, the effect of the present invention is remarkable. Since the element containing zinc element is poor in chemical resistance of the element, the corrosion of the element becomes undesirably large in the treatment with the conventional plating solution, and there is a possibility that defects such as defective insulation are likely to occur. On the other hand, by using the method for manufacturing a ceramic electronic component according to the present invention, such a problem can be sufficiently suppressed.

  According to the present invention, by preparing the plating solution so that the pH is 6 or more and 9 or less, and the value of the molar concentration of the chelating agent / the molar concentration of tin ions is greater than 2.4 and 4.5 or less, Corrosion of the element body of the ceramic electronic component by the plating solution can be suppressed, and stable plating can be performed.

It is a perspective view which shows schematic structure of a ceramic electronic component. It is sectional drawing of the II-II line of FIG. It is a schematic sectional drawing which shows the structure where the terminal electrode was formed by plating on the outer side of the base electrode of the ceramic electronic component. It is a figure which shows the relationship between the value of the molar concentration of a chelating agent in a plating solution / molar concentration of tin ion, and corrosion distance. It is a figure which shows the relationship between pH of a plating solution, and a corrosion distance. It is a figure which shows the relationship between the density | concentration of the chelating agent in a plating solution, and corrosion distance. It is a figure which shows the relationship between the density | concentration of the conductive salt in a plating solution, and a corrosion distance. It is a figure which shows the relationship between the temperature of a plating solution, and a corrosion distance.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. Further, the following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention only to the embodiments. Furthermore, the present invention can be variously modified without departing from the gist thereof.

<Examples of ceramic electronic components>
FIG. 1 is a perspective view showing an example of a ceramic electronic component to be subjected to electroplating processing according to the present invention. 2 is a cross-sectional view taken along line II-II in FIG.

  The ceramic electronic component 1 has a laminated body 4 including an element body 2 made of ceramics and a plurality of internal electrodes 3 formed in the element body 2. In other words, the element body 2 and the internal electrodes 3 are laminated. At least one unit structure 10 is provided. More specifically, the internal electrodes 3 having end portions exposed on one side surface of the multilayer body 4 and the internal electrodes 3 having end portions exposed on the other side surface of the multilayer body 4 are alternately stacked. . Base electrodes 5 and 5 are provided on both sides (ends) of the multilayer body 4 so as to cover the side surfaces thereof, and each ground electrode 5 is formed of the internal electrode 3 exposed from one side surface of the multilayer body 4. A group or a group of internal electrodes 3 exposed from the other surface of the laminate 4 is electrically connected.

  The element body 2 of the ceramic electronic component 1 is made of ceramics, specifically, semiconductor ceramics or dielectric ceramics. In both cases of semiconductor ceramics and dielectric ceramics, the element body 2 may contain a zinc element. For semiconductor ceramics, glass containing zinc element is preferably used as the main component of varistors, thermistors and the like, and for dielectrics, glass containing zinc element as a sintering aid. Particularly in the latter case, as the LTCC (parts) is miniaturized, the layer thickness is reduced. For this reason, the sintering temperature is further lowered, and the use examples are further increased.

  For the internal electrode 3, for example, a material mainly composed of silver, palladium, nickel, copper, or aluminum is used from the viewpoint of enabling reliable ohmic contact with the element body 2. There is no limitation.

  The base electrode 5 is obtained, for example, by applying and baking a conductive paste on the side surface of the multilayer body 4. Examples of the conductive paste for forming the base electrode 5 mainly include glass powder (frit), organic vehicle (binder), and metal powder. By firing the conductive paste, the organic vehicle is The base electrode 5 that volatilizes and finally contains a glass component and a metal component is formed. In addition, you may add various additives, such as a viscosity modifier, an inorganic binder, and an oxidizing agent, to an electrically conductive paste as needed. For example, the base electrode 5 contains silver, copper, or zinc as a metal component.

  As shown in FIG. 3, terminal electrodes 7 and 7 are further formed on the surfaces of the base electrodes 5 and 5 of the ceramic electronic component 1 by electroplating. These terminal electrodes 7 and 7 are joined to, for example, electrodes on the wiring board by solder or the like. Each terminal electrode 7 has, for example, a two-layer structure including a nickel layer 7a and a tin layer 7b that are stacked from the base electrode 5 side. The nickel layer 7a functions as a barrier metal that prevents poor soldering due to mutual diffusion between the tin layer 7b and the base electrode 5 due to heat during soldering, and has a thickness of, for example, about 2 μm. The tin layer 7b has a function of improving the wettability of the solder, and the thickness thereof is, for example, about 4 μm.

<Plating solution>
The plating solution according to the present embodiment is suitably used for forming an electrode of a ceramic electronic component such as the tin layer 7b described above. Hereinafter, the plating solution according to the present embodiment will be described.

  The plating solution according to the present embodiment includes, for example, tin ions, a chelating agent, a conductive salt (conductive agent), and a pH adjuster. Hereinafter, each component will be described.

  Examples of tin ion sources include tin alkane sulfonates such as tin methanesulfonate, tin sulfate, tin sulfamate, tin chloride, stannous acetate, stannous oxide, stannous borofluoride, 2-hydroxyethanesulfonic acid Examples thereof include stannous, stannous 2-hydroxypropane sulfonate, and stannous phenol sulfonate. Among these, it is preferable to use tin methanesulfonate from the viewpoints of handleability and stability.

  A chelating agent is added for solubilization and dissolution stabilization of tin ions. Examples of the chelating agent include gluconic acid, glucoheptonic acid, gluconolactone, glucoheptonolactone, citric acid, pyrophosphoric acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof. Specific examples include sodium gluconate (sodium gluconate), magnesium gluconate, calcium citrate, and strontium pyrophosphate. Of these, gluconate is preferred because it can enhance the stability of the plating solution.

  In this embodiment, the value of the molar concentration of the chelating agent / the molar concentration of tin ions (molar ratio) is adjusted to be larger than 2.4 and 4.5 or smaller. As shown in Examples described later, when the value of the molar concentration of the chelating agent / the molar concentration of tin ions is 2.4 or less, precipitation occurs during standing or energization, and the composition of the plating solution fluctuates and is stable. Tends to be difficult. Moreover, when the value of the molar concentration of the chelating agent / the molar concentration of tin ions exceeds 4.5, the element body of the ceramic electronic component tends to corrode.

  Since the chelating agent used for tin plating has a large complex ion formation constant, when the chelating agent is contained in a large amount, the element body itself made of ceramics tends to be easily dissolved. Specifically, when the concentration of the chelating agent is 0.3 mol / L or less, corrosion of the element body is significantly suppressed.

  In the present embodiment, the pH of the plating solution is adjusted to 6 or more and 9 or less. As shown in the examples described later, when the pH exceeds 9, precipitation occurs during standing or energization, the composition of the plating solution varies, and stable plating tends to be difficult. On the other hand, when the pH is less than 6, the body of the ceramic electronic component tends to corrode.

  There are no particular limitations on the type of pH adjuster, but for example, ammonia, hydroxides of alkali metals such as sodium hydroxide, and alkaline earth hydroxides such as strontium hydroxide and magnesium hydroxide are used. .

  The conductive salt is added as a conductive agent in order to increase the conductivity of the plating solution. Examples of the conductive agent include alkali metal, alkaline earth metal, or ammonia, alkanesulfonic acid such as methanesulfonic acid, sulfuric acid, sulfamic acid, acetic acid, borofluoric acid, 2-hydroxyethanesulfonic acid, and 2-hydroxypropanesulfone. Examples include acids and salts with acids such as phenolsulfonic acid, or chlorides. Specific examples include magnesium methanesulfonate, ammonium methanesulfonate, calcium chloride, strontium sulfate, sodium sulfate, ammonium chloride, sodium sulfamate and the like. Among these, ammonium salts such as ammonium chloride tend to corrode the element body, and sulfamate such as sodium sulfamate tends to precipitate when energized. In order to prevent such precipitation of sulfamate, the sulfamate ion concentration is preferably less than 0.5 mol / L.

  When an alkali metal salt or an alkaline earth metal salt is used as the conductive salt, for example, the molar concentration of the conductive salt / the molar concentration of tin ions is adjusted to be 2 or more and smaller than 12. If the value of the molar concentration of conductive salt / the molar concentration of tin ions is smaller than 2, soldering tends to occur when soldering is performed on the plating film. Further, when the value of the molar concentration of the conductive salt / the molar concentration of tin ions is 12 or more, precipitation occurs during standing or energization, the composition of the plating solution varies, and stable plating tends to be difficult.

  Here, it is preferable that ammonia and ammonium ions are not contained as much as possible, and may not be contained at all. When ammonia or ammonium ions are included, the corrosion of the element itself tends to proceed. Specifically, when ammonia and ammonium ions are set to 0.3 mol / L or less, corrosion of the element body is significantly suppressed.

  In addition, the plating solution according to the present embodiment may contain a known additive such as a brightener or a surfactant as necessary, and even in that case, the additive solution may satisfy the above-described condition. It is preferable to select the type and adjust the amount.

  The temperature of the plating solution is preferably larger than 5 ° C and smaller than 35 ° C. When the temperature of the plating solution is 5 ° C. or lower, precipitation occurs when left standing or energized, the composition of the plating solution varies, and stable plating tends to be difficult. If the temperature of the plating solution exceeds 35 ° C., soldering tends to occur when soldering is performed on the plating film.

  The plating method according to the present embodiment is a method in which tin is electroplated on a ceramic electronic component with the above-described electrotin plating solution. As a plating method, for example, barrel plating can be used. If necessary, the agitation can be carried out by a method of flowing the plating solution using a cathode swing or a pump.

  Known conditions can be used as the plating conditions. For example, tin metal is usually used as the anode, but insoluble electrodes such as platinum-plated titanium plates may be used in some cases. Plating conditions such as cathode current density and plating time can be appropriately determined by those skilled in the art according to the required film thickness of the tin layer. According to such a plating method according to the present embodiment, it is possible to suitably suppress the corrosion of the element body by the plating solution.

  Moreover, the plating solution and the plating method according to the present embodiment can be preferably used for a ceramic electronic component including an element body containing a zinc element. When zinc element is included, particularly when zinc element is included in the grain boundary component of the element body, the chemical resistance of the element body becomes poor, so the effect of the plating solution according to the present embodiment becomes more remarkable. .

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
In advance, 50 types of electrotin plating solutions having the compositions shown in Table 1 were prepared by changing the molar concentration of the chelating agent. A chip capacitor in which the main composition of the element body is barium titanate and the outer shape is 1.6 × 0.8 × 0.8 mm, and a copper base electrode is formed by applying a copper paste to the end portion and firing it. 10,000 pieces were prepared. Next, the insulation resistance (IR) of all the chips was measured, and those having an IR of 10 ⁸ Ω or less were evaluated as IR defects. Next, tin plating was performed with a plating solution in the table using a barrel plating apparatus to form a 4 μm tin layer. Next, the corrosion distance of the element body was examined for the chips treated with each plating solution. The corrosion distance indicates an average value when ten chips after plating are sampled (sampled), and the thickness of the corrosion layer on the element body surface is measured by cross-sectional observation of the SEM. The results are shown in Table 1 and FIG. In all the tables including Table 1 and FIG. 4, “chelating agent / tin (Sn) salt” indicates the molar concentration of the chelating agent / molar concentration of tin ion, and “conductive salt / tin salt” indicates the conductive salt. Mole concentration / tin ion molar concentration value is shown.

  As shown in FIG. 4, it was found that when the molar concentration of the chelating agent / the molar concentration of tin ions (molar ratio) exceeds 4.5, the corrosion distance increases rapidly. Further, as shown in Table 1, it was found that the overall corrosion distance increases as the pH decreases.

Further, an IR test was performed on all the chips after plating, and a chip having a resistance of 10 ⁸ Ω or less was regarded as defective. The results are shown in Table 1. It has been found that when the corrosion distance exceeds 1 μm, an IR defect occurs, and that when the pH is 5, an IR defect occurs in all cases.

  FIG. 5 shows the relationship between the pH and the corrosion distance when the value of the molar concentration of the chelating agent / the molar concentration of tin ions is 4.5. As shown in FIG. 5, it was found that the corrosion was smallest when the pH was 8, and the corrosion rapidly increased when the pH was lower than 6.

  In addition, 100 mL of each plating solution sample was collected and allowed to stand for 1 month to investigate the presence or absence of precipitation. The results are shown in Table 1. It was found that precipitation occurs when the pH is 6 or more and the molar concentration of the chelating agent / the molar concentration of tin ions is less than 2.5. In addition, 100 mL of each sample in which the molar concentration of the chelating agent / the molar concentration of tin ions was changed by 0.1 with a plating solution of pH 6, 7, 8, and 9 was prepared, and after standing for one month, the presence or absence of precipitation was examined. The minimum value at which precipitation occurred at pH was investigated. The results are shown in Table 2. When the pH exceeded 9, precipitation occurred regardless of the value of the molar concentration of the chelating agent / the molar concentration of tin ions.

  From the above results, the preferable range of the composition of the plating solution is that the molar concentration of the chelating agent / the molar concentration of tin ions (molar ratio) exceeds 2.4 and is 4.5 or less, and the pH is 6 or more and 9 or less. found. When the value of the molar concentration of the chelating agent / the molar concentration of tin ions is 2.4 or less, precipitation occurs in the set pH range, and when it is larger than 4.5, the corrosion distance exceeds 1 μm and IR failure occurs. When the pH is less than 6, the corrosion distance is long and IR failure occurs. When the pH exceeds 9, precipitation occurs regardless of the value of the molar concentration of the chelating agent / the molar concentration of tin ions.

(Example 2)
In Example 1, the value of the molar concentration of the chelating agent / the molar concentration of tin ions was kept constant, and the molar concentration of the chelating agent was changed. The results are shown in Table 3 and FIG.

  As shown in FIG. 6, when the molar concentration of the chelating agent exceeds 0.3 mol / L, the corrosion distance increases rapidly, and as shown in Table 3, when the molar concentration of the chelating agent exceeds 0.5 mol / L, the IR failure occurs. Was found to occur.

(Example 3)
Ten types of electrotin plating solutions were prepared in advance using sodium methanesulfonate as the alkali conductive salt and changing its molar concentration. The ten types of electrotin plating solutions were evaluated for the presence or absence of precipitation, the corrosion distance of the ceramic body, the IR failure rate, and the soldering failure. The results are shown in Table 4.

  As shown in Table 4, the corrosion distance does not depend on the molar concentration of alkali conductive salt / molar concentration of tin ions, but when the molar concentration of alkaline conductive salt / molar concentration of tin ions is less than 2, poor soldering occurs. Turned out to be. This is thought to be due to the fact that tin crystals become coarse and are easily oxidized. On the other hand, when the value of the molar concentration of alkali conductive salt / the molar concentration of tin ions is 12 or more, precipitation occurs. From the above, it was found that the preferable range of the molar concentration of the alkali conductive salt / the molar concentration of the tin ion is 2 ≦ alkali conductive salt / tin salt <12.

  Similar results were obtained when the alkali conductive salt was an alkali metal salt other than Na, such as potassium methanesulfonate and lithium methanesulfonate. The same results were obtained even when the salt of an acid other than methanesulfonic acid such as sodium carbonate or sodium sulfate and an alkali metal was used.

Example 4
The experiment was conducted by replacing the alkaline conductive salt of Example 3 with an alkaline earth conductive salt. That is, ten types of electrotin plating solutions were prepared using strontium metal sulfonate (Sr) as the alkaline earth conductive salt and changing its molar concentration. The ten types of electrotin plating solutions were evaluated for the presence or absence of precipitation, the corrosion distance of the ceramic body, the IR failure rate, and the soldering failure. The results are shown in Table 5.

  In Example 4, it was found that the same results as in Example 3 were obtained. That is, as shown in Table 5, the corrosion distance does not depend on the value of the alkaline earth conductive salt molar concentration / tin ion molar concentration, but the alkaline earth conductive salt molar concentration / tin ion molar concentration is less than 2. Then, it became clear that a soldering defect occurred. On the other hand, precipitation occurs when the value of the molar concentration of alkaline earth conductive salt / the molar concentration of tin ions is 12 or more. From the above, it was found that the preferable range of the molar concentration of alkaline earth conductive salt / the molar concentration of tin ions is 2 ≦ alkaline earth conductive salt / tin salt <12.

(Example 5)
An experiment was conducted by replacing the alkali conductive salt of Example 3 with an ammonia conductive salt. That is, nine types of electrotin plating solutions were prepared using ammonium methanesulfonate as the ammonia conductive salt and changing its molar concentration. And about nine types of electrotin plating solutions, the presence or absence of precipitation, the corrosion distance of the ceramic body, the IR failure rate, and the soldering failure were evaluated. The results are shown in Table 6.

  It has been found that when the molar concentration of the ammonium conductive salt exceeds 0.3 mol / L, the corrosion of the element increases and IR failure occurs. Accordingly, it has been found that the concentration of ammonium ions in the plating solution needs to be suppressed to 0.3 mol / L or less.

(Example 6)
A similar experiment was performed by changing the temperature of the plating solution. That is, nine types of electrotin plating solutions having different temperatures were evaluated for the presence or absence of precipitation, the corrosion distance of the ceramic body, the IR failure rate, and the soldering failure. The results are shown in Table 7.

  As shown in Table 7, the corrosion distance does not greatly depend on the plating solution temperature, but it has been found that poor solderability occurs when the temperature is 35 ° C. or higher. This is thought to be due to the fact that when the plating solution temperature rises, the tin crystals become coarse and are easily oxidized. In addition, precipitation occurs when the temperature reaches 5 ° C. As a result, it was found that the preferable range of the plating solution temperature was 5 ° C. <plating solution temperature <35 ° C.

(Example 8)
A similar experiment was performed by adding sulfamate to the plating solution. The results are shown in Table 8.

  As shown in Table 8, it was found that precipitation occurred when the molar concentration of sulfamate was 0.5 mol / L or more.

  INDUSTRIAL APPLICABILITY The present invention can be widely used for plating treatment of ceramic electronic parts including thermistors, capacitors, inductors, LTCC (Low Temperature Co-fired Ceramics), varistors, and composite parts thereof.

  DESCRIPTION OF SYMBOLS 1 ... Ceramic electronic component, 2 ... Element body, 3 ... Internal electrode, 4 ... Laminated body, 5 ... Base electrode, 7 ... Terminal electrode, 7a ... Nickel layer, 7b ... Tin layer, 10 ... Unit structure.

Claims (8)

An electrotin plating solution for ceramic electronic components,
Containing tin ions and chelating agents,
pH is 6 or more and 9 or less,
The ratio of the molar ratio of the chelating agent / the molar concentration of the tin ions in the electrotin plating solution is greater than 2.4 and not greater than 4.5.
Electro tin plating solution. Including sulfamic acid ions derived from the tin ion supply substance or other additives,
The sulfamic acid ion concentration in the electrotin plating solution is less than 0.5 mol / L.
The electrotin plating solution according to claim 1. The chelating agent concentration in the electrotin plating solution is 0.3 mol / L or less,
The electrotin plating solution according to claim 1 or 2. Contains ammonia or ammonium ions,
The concentration of the ammonia and the ammonium ion in the electrotin plating solution is 0.3 mol / L or less,
The electrotin plating solution according to claim 1. A conductive agent that is a salt of an alkali or alkaline earth metal;
The ratio of the molar concentration of the conductive agent to the molar concentration of tin ions in the electrotin plating solution is 2 or more and less than 12.
The electrotin plating solution according to claim 1. The temperature is greater than 5 ° C and less than 35 ° C,
The electrotin plating solution according to any one of claims 1 to 5. Comprising a step of forming a tin layer on the underlying electrode of the ceramic element using electrotin plating;
In the step, tin ions and a chelating agent are included, the pH is 6 or more and 9 or less, and the ratio of the molar concentration of the chelating agent / the molar concentration of the tin ions in the electrotin plating is greater than 2.4. .. using an electroplating solution that is 5 or less,
Manufacturing method of ceramic electronic components. The ceramic body contains zinc;
A method for manufacturing a ceramic electronic component according to claim 7.