JP2001060532A - Formation of external electrode of laminated ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form highly reliable external electrodes which can be applied to an extremely small laminated ceramic capacitor, etc., and have high heat cycle resistance and high solderability. SOLUTION: In a method for forming external electrodes, external electrodes are formed of Ag or Cu base electrode layers which are formed on both ends of an elemental laminated ceramic body, in a state where the electrode layers are connected with internal electrodes, intermediate plated Ni layers which are formed on the base electrode layers, and outermost Sn, Sn/Pb, Sn/Cu, Sn/Bi, or Sn/Zn layers formed on the intermediate plated Ni layers. The intermediate plated Ni layers are formed through the use of an Ni-plating solution containing at least one or more kinds of sulfonic acid-based compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component including a multilayer ceramic capacitor, a multilayer varistor, a multilayer dielectric resonator, a multilayer piezoelectric element, and the like. This is a method for forming external electrodes of the multilayer ceramic electronic component to be formed.

[0002]

2. Description of the Related Art As electronic devices and the like have been reduced in size, discrete components have become smaller as surface mount type components. In particular, there is an increasing demand for miniaturization of multilayer ceramic capacitors used in high- and low-voltage integrated circuits. Accordingly, it is desired that the external electrodes have good bonding properties with the electric circuit, excellent electrical characteristics, reliability, and mechanical characteristics, and also have high bonding strength with the multilayer ceramic body which is a sintered body. ing.

Generally, multilayer ceramic electronic components are Pd,
An internal electrode made of a conductive paste containing a noble metal such as Pt or Ag / Pd as a main component is printed on a dielectric ceramic green sheet, and the ceramic green sheet is alternately laminated and fired with the internal electrode in a plurality of layers. And external electrodes are formed at both ends of the multilayer ceramic body.

Conventionally, as an external electrode, a conductive paste containing a metal powder such as Ag or Cu as a main component and a glass frit as a main component so as to improve the familiarity with the internal electrode and prevent a connection failure from occurring is used. 2. Description of the Related Art A base electrode layer is provided as a first electrode layer in a well-bonded state that is applied to both ends and baked to fuse with a noble metal of an internal electrode and has a good bonding state.

Further, in order to improve wettability and solder resistance for soldering and fixing to an electric circuit of a mounted board,
An external electrode is formed by depositing an intermediate electrode layer made of a plating film of Ni or the like on a base electrode layer and further laminating an outermost electrode layer made of a plating film of Sn or Sn / Pb or the like. .

[0006] Among the layers forming the external electrodes, an intermediate electrode layer is mainly formed of a Ni plating film. This N
Since the i-plated film is extremely thin as a film portion, it is processed by barrel plating using a watt bath having a basic composition because it is necessary to ensure current efficiency.

[0007] It is originally desirable to treat with a sulfamic acid bath having a low electrodeposition stress, that is, a low NiCl ₂ .6H ₂ O (nickel chloride) bath composition which leaves a large residual stress. However, since it is necessary to use nickel bromide (NiBr ₂ ) for replenishing Ni ions, a watt bath is used in consideration of safety and health and economic costs.

However, when a large amount of solder is used for the above-mentioned external electrodes and soldering is performed, there is a tendency that the heat cycle resistance at −55 to 125 ° C. is deteriorated. Therefore, Ni
If the thickness of the plating film is increased, the tensile stress of the plating film increases as the thickness increases, and conversely, the heat cycle resistance deteriorates, resulting in a vicious cycle.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks and can be applied to very small multilayer ceramic capacitors, etc., and has excellent heat cycle resistance, good solderability and high reliability. An object of the present invention is to provide a method for forming external electrodes of a multilayer ceramic electronic component for forming electrodes.

[0010]

According to a first aspect of the present invention, there is provided a method for forming an external electrode of a multilayer ceramic electronic component, wherein the underlayer of Ag or Cu is attached to both ends of a multilayer ceramic body by being connected to an internal electrode. An electrode layer, an intermediate Ni plating layer deposited on the base electrode layer, and Sn or Sn / Pb, Sn / Cu, S of the outermost layer deposited on the Ni plating layer.
An external electrode is formed from any one of n / Bi and Sn / Zn plating layers. An intermediate Ni plating layer is formed by a Ni plating solution containing at least one or more sulfonic acid compounds. Have been.

In the method for forming an external electrode of a multilayer ceramic electronic component according to a second aspect of the present invention, the additive amount is 1 to 40.
An intermediate Ni plating layer is formed by a Ni plating solution containing a sulfonic acid compound at a concentration of ml / L.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming an external electrode of a multilayer ceramic electronic component according to the present invention is a method of forming an internal electrode made of a conductive paste containing a noble metal such as Pd, Pt, Ag / Pd as a main component. The method is applied to printing on a sheet, firing a plurality of the ceramic green sheets alternately with the internal electrodes and firing them to form a multilayer ceramic body, and then providing external electrodes at both ends of the multilayer ceramic body.

[0013] The external electrode is composed of an Ag or Cu base electrode layer connected to the internal electrode and attached to both ends of the multilayer ceramic body, an intermediate Ni plating layer attached to the base electrode layer, and Sn or Sn / Pb, Sn / Cu, Sn / Bi, Sn / Zn of the outermost layer adhered to the Ni plating layer
Are formed by laminating any one of the plating layers.

Among the layers forming the external electrodes, an intermediate Ni plating layer is formed by a Ni plating solution containing at least one sulfonic acid compound. In particular, N containing a sulfonic acid compound in an addition amount of 1 to 40 ml / L
It is preferable to use an i plating solution. This makes it possible to form an external electrode having good heat cycle resistance and good solderability.

In order to confirm its effectiveness, RSO ₂ NH ₂ (sulfonamide) having SO ₃ H groups as shown in Table 2 was obtained under the Ni plating composition bath and operating conditions shown in Table 1 below. Using a Ni plating solution with a different addition amount,
External electrodes having an intermediate plating layer formed from a plating solution were provided at both ends of the multilayer ceramic capacitor body, and the number of occurrences of poor heat cycle resistance and poor solderability was inspected for each of 20 pieces.

[0016]

[Table 1]

[0017]

[Table 2]

Regarding heat cycle resistance and soldering resistance, as shown in Table 2, the amount of RSO ₂ NH ₂ (sulfonic acid amide) having SO ₃ H group added to the plating solution was 1.
Good results were obtained with an external electrode having an intermediate Ni plating layer formed with a Ni plating solution of 0 to 40.0 ml / L.

On the other hand, the amount of sample 1 added was 0.5 ml /
In the case of L, the solderability is slightly improved as compared with the addition amount 0 of the conventional example, but the defective rate of heat cycle resistance is as high as 5%, which is not suitable for mass production.

When the addition amount of the sample 9 is 45.0 ml / L or more, the defective rate of the heat cycle resistance is 10% or more,
The defective rate of solderability is 5% or more, which is not suitable for mass production. Thereby, RSO ₂ NH having an SO ₃ H group is obtained.
₂ (sulfonic acid amide) added amount is 1.0 to 40.0 m
It can be understood that an external electrode having an intermediate Ni plating layer formed with 1 / L Ni plating solution is preferable.

Generally, RSO ₂ NH having an SO ₃ H group
₂ According to the watt bath which does not contain (sulfonamide) as an additive, the electrodeposition stress is large, but as it is added or its amount is increased, the hardness and tensile strength increase, and the elongation decreases. Gives brittleness. For this reason, RS
By adding O ₂ NH ₂ (sulfonamide), the electrodeposition stress, that is, the tensile stress is reduced and the stress is changed to the compressive stress, whereby the heat cycle resistance can be improved.

On the other hand, RSO ₂ NH ₂ having an SO ₃ H group
When the amount of (sulfonamide) added is 40.0 ml / L or more, the tensile strength increases, the brittleness increases, and the heat cycle resistance and the solderability deteriorate. In addition, it can be inferred that the tensile stress of the Ni plating layer due to RSO ₂ NH ₂ is reduced by changing the inside of precipitated Ni crystal grains.

[0023]

As described above, according to the method for forming an external electrode of a multilayer ceramic electronic component according to the first aspect of the present invention, Ag or Cu which is connected to an internal electrode and adheres to both ends of a multilayer ceramic body is provided. , An intermediate Ni plating layer deposited on the underlying electrode layer, and Sn or Sn / Pb, Sn / Cu, Sn / B of the outermost layer deposited on the Ni plating layer.
An external electrode is formed from any one of i, Sn / Zn and a plating layer. An Ni plating solution containing at least one or more sulfonic acid compounds is used to form an intermediate Ni.
By forming the plating layer, a highly reliable external electrode having excellent heat cycle resistance and good solderability is provided on the multilayer ceramic electronic component.

According to the method for forming an external electrode of a multilayer ceramic electronic component according to claim 2 of the present invention, the additive amount is 1 to 40 m.
By forming an intermediate Ni plating layer with a Ni plating solution containing 1 / L of a sulfonic acid-based compound, the heat cycle resistance is excellent based on a specific value of the addition amount, and the solderability is good. High external electrodes are provided on the multilayer ceramic electronic component.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayuki Okabe 151 Maeda, Hirasawa, Nikaho-cho, Yuri-gun, Akita F-term in TDCMCC Co., Ltd. FF05 FG06 FG26 GG10 GG11 GG28 JJ03 JJ12 JJ23 PP03

Claims (2)

[Claims] 1. An Ag or Cu base electrode layer connected to an internal electrode and applied to both ends of a multilayer ceramic body, an intermediate Ni plating layer applied to the base electrode layer, and an Ni plating layer Sn or Sn / Pb, Sn of the outermost layer to be deposited
/ Cu, Sn / Bi, Sn / Zn, in a method for forming an external electrode from a plating layer of any one of Sn / Zn, a Ni plating solution containing at least one or more sulfonic acid compound. A method for forming external electrodes of a multilayer ceramic electronic component, wherein an intermediate Ni plating layer is formed by the method described above. 2. An external electrode for a multilayer ceramic electronic component according to claim 1, wherein an intermediate Ni plating layer is formed by a Ni plating solution containing a sulfonic acid compound in an addition amount of 1 to 40 ml / L. Method.