JP4083971B2 - Multilayer ceramic electronic component and manufacturing method thereof - Google Patents

Description

表１中、Ｃｐ：静電容量、Tanδ：損失係数、ＩＲ：絶縁抵抗である。
【００２５】
上記表１から下地電極層であるＣｕ焼付層厚１.００μｍ以上であれば、Ｃｐ，Tanδ，ＩＲ共に良好でＮｉ硫化物等の析出物も無く、従来品と同等であることが判る。特に実施例１の如く、層厚が薄いと内部電極のＮｉがイオン化し、Ｎｉ硫化物として内部電極層及び外部に析出し電気的特性を悪化させる要因になっている。これに対して実施例２、実施例３の如く、層厚が１.００μｍ以上になると、焼成温度で更にそのＮｉ硫化物と反応して、即ち、層上に形成されているＡｇ−Ｐｄが媒体となって内部電極の露出するＮｉ層とＣｕの下地電極層の界面にＣｕ−Ｎｉ合金接合部を形成して交互の接触を強固にすると共に、導電を良好にしていると推察できる。
【００２６】
従って、従来の場合は外部接続端子電極を形成するのにメッキ等の形成工程が必要であったのが、メッキ等の形成工程を省力化でき、煩雑な工程となるのを防ぐことができコスト的にも安価に製造することが可能となる。
【００２７】
（実験２）
次に、実施例１、実施例２及び実施例３の積層セラミックコンデンサを各１００個選び、ヒートサイクル試験後のクラック発生数及びＰｂフリーはんだ処理に対する耐熱性良否を検証し、その結果を以下の表２に示す。
【００２８】
【表２】

上記表２に示した如く、下地電極層であるＣｕ層厚が１.００μｍ以上の範囲でクラック発生が無く、耐熱性も良く、同様に良好な結果が得られた。厚さ１.００μｍ未満であると薄すぎて耐熱性が劣り、即ち、硫化物の析出で、空洞化が生じ、冷却（室温２５℃）時に収縮が起きヒートサイクル試験でクラックが発生する。このクラック発生数は少なく判断され易いが、大量生産においては大きな不良率を誘起し生産歩留の低下に繋がる。
【００２９】
従って、耐熱性から下地電極層であるＣｕ層膜を厚くすることは必要であるが、高張力や圧縮力を考慮すると、耐熱性が維持できる最低限の厚さに確保すればよく、その厚さの範囲は少なくとも１.００μｍで充分であることが理解できる。なお、下地電極層は必要以上に厚くないことが好ましく、３μｍ以下であることが望ましい。
【００３０】
以上本発明の実施の形態について説明してきたが、本発明はこれに限定されることなく請求項の記載の範囲内において各種の変形、変更が可能なことは当業者には自明であろう。
【００３１】
【発明の効果】
以上説明したように、本発明によれば、Ｎｉ又はＮｉ合金層の内部電極を内設した積層セラミック素体の両端に外部接続端子電極を形成する場合において、前記外部接続端子電極はＣｕ又はＣｕ合金を主成分とする下地電極層と、Ａｇ又はＡｇ合金を主成分とする最外部電極層との重層で形成されているので、鉛（Ｐｂ）フリーはんだで回路基板に電気的通電固着する際に生じる特性影響を防止でき、耐ヒートサイクル性の高い外部接続端子電極を形成できる。また、メッキ等の形成工程も省力化でき、煩雑な工程を防ぐことができコスト的にも安価に製造することが可能である。この結果、極小積層セラミックコンデンサ等にも適用できる積層セラミック電子部品を従来品と同等な電気的特性を維持すると共に廉価に実現することが可能となる。
【図面の簡単な説明】
【図１】本発明に係る積層セラミック電子部品の実施の形態を示す正断面図である。
【図２】従来の積層セラミック電子部品の正断面図である。
【符号の説明】
１，１１ 積層セラミックコンデンサ
２，１２ 誘電体
３，１３ 内部電極
４，１４ 積層セラミック素体
５，１５ 外部接続端子電極
５ａ 第１電極層
５ｂ 第２電極層
５ｃ 第３電極層
１５ａ 下地電極層
１５ｂ 最外部電極層
１６ 合金層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer ceramic electronic component such as a multilayer ceramic capacitor, a multilayer varistor, a multilayer dielectric resonator, a multilayer piezoelectric element, and a method for manufacturing the multilayer ceramic electronic component, and in particular, electrically conductively fixed to a circuit board with lead (Pb) -free solder. The present invention relates to a multilayer ceramic electronic component in which an external connection terminal electrode having high heat cycle resistance capable of preventing the influence of sulfurous acid gas generated during the process and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, electronic devices and the like have been miniaturized, and discrete components have become surface mount type miniature chip components. For example, multilayer ceramic capacitors used for high-voltage or low-voltage integrated circuits are also required to be miniaturized. It is getting stronger. For this reason, it has good bondability with electrical circuits, excellent electrical characteristics, reliability, and mechanical characteristics, and has high bonding strength with the multilayer ceramic body of the sintered body, as well as flexural strength and heat cycle resistance. The demand for highly external connection terminal electrodes is becoming stronger.
[0003]
For example, as shown in FIG. 2, a multilayer ceramic capacitor 1 as a conventional multilayer ceramic electronic component is formed by sequentially laminating and firing a ceramic green sheet of a dielectric 2 on which an internal electrode 3 using a base metal such as Ni is printed, At both ends of the multilayer ceramic body 4 formed by cutting into a plurality, the familiarity with the internal electrode 3 as the external connection terminal electrode 5 is improved, and Ag—Pd or A conductive paste obtained by adding glass frit to a metal powder such as Cu is applied and baked at 700 to 800 ° C. to form the first electrode layer 5a of the base electrode layer, which is fused with the noble metal or base metal of the internal electrode 3. The first electrode layer 5a and the internal electrode 3 are in a good coupled state.
[0004]
The external connection terminal electrode 5 is provided on the first electrode layer 5a in order to maintain wettability and solder resistance, particularly solder heat resistance, when connected to an electric circuit on a substrate to be mounted. In order to improve the consistency between the second electrode layer 5b made of a plating film of Ni or the like and the solder used for external electrical connection, the third electrode layer 5c made of Sn or Sn-Pb is further coated. Forming. The second electrode layer 5b is generally formed of a Ni plating layer having a thickness of 1.0 to 3.0 [mu] m. Since the coating is extremely small, a watt bath having a basic composition is used to ensure current efficiency. It is processed by the barrel plating used.
[0005]
Although it is ideally treated with a sulfamic acid bath having a low electrodeposition stress, that is, a NiCl ₂ .6H ₂ O (nickel chloride) bath composition that leaves a large residual stress, it is brominated by Ni ion supplementation. Since nickel (NiBr ₂ ) is used, a watt bath is generally used in consideration of safety and health and economic costs.
[0006]
However, when soldering with a large amount of solder is applied to the external connection terminal electrode 5 formed in this manner, the Ni plating layer tends to deteriorate with respect to the heat cycle resistance of -55 to 125 ° C. Has been addressed by increasing the film thickness. On the other hand, as the film thickness increases, tensile stress and compressive stress of the plating film are generated, resulting in a vicious circle in which heat cycle resistance deteriorates.
[0007]
However, in recent years, there has been a growing demand for electronic parts that support conductive adhesives for lead-free mounting, and as described above, the outermost electrode layer of the external connection terminal electrode is formed as an Sn or Sn-Pb electrode layer. The outermost electrode layer is made of Ag or an Ag-Pd alloy because the contact resistance is greatly increased in a high temperature and humidity environment, the reliability is inferior, and the deterioration of the fixing strength is observed in the heat cycle. Has been used.
[0008]
However, if the internal electrode is made of a base metal Ni or Ni alloy layer at a low cost, the internal electrode undergoes oxidative corrosion in a sulfurous acid gas (H ₂ SO ₃ ) test corresponding to a highly oxidizing plating bath atmosphere. Nickel sulfide (NiS) or nickel sulfate generated in (1) is deposited on the surface of the electronic component, which has the disadvantage of causing insulation failure (IR failure) and capacity reduction.
[0009]
[Problems to be solved by the invention]
The present invention eliminates the above-mentioned drawbacks, and forms an external connection terminal electrode with high heat cycle resistance that can prevent the influence of characteristics that occur when electrical conduction is fixed to a circuit board with lead (Pb) -free solder. An object of the present invention is to provide a multilayer ceramic electronic component that can be applied to a capacitor and the like, and a method of manufacturing the same.
[0010]
Other objects and novel features of the present invention will be clarified in embodiments described later.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a multilayer ceramic electronic component according to the present invention is a multilayer ceramic electronic component in which external connection terminal electrodes are formed at both ends of a multilayer ceramic body in which an internal electrode of a Ni or Ni alloy layer is provided. The external connection terminal electrode is formed of two layers of a base electrode layer mainly composed of Cu or Cu alloy and an outermost electrode layer mainly composed of Ag—Pd alloy. The base electrode layer is made of Cu or Cu alloy. The outermost electrode layer is formed by a conductive paint containing a conductive metal material mainly composed of an Ag-Pd alloy and a glass frit, and is formed by a conductive paint containing a conductive metal material containing glass frit as a main component. It is formed simultaneously with the underlying electrode layer in the layer are Cu-Ni alloy is formed at the interface between the Ni or Ni alloy layer and the underlying electrode layer of the internal electrodes are exposed at both ends of the multilayer ceramic element assembly Underlying electrode layer has a thickness of at 1μm or more.
[0012]
Preferably, the base electrode layer has a thickness of 1 μm or more.
[0015]
The method for manufacturing a multilayer ceramic electronic component according to the present invention includes a method for manufacturing a multilayer ceramic electronic component in which external connection terminal electrodes are formed at both ends of a multilayer ceramic body having an internal electrode of a Ni or Ni alloy layer. The manufacturing process of the terminal electrode includes a first conductive paste application process in which a conductive paste of a base electrode material including a conductive metal material mainly composed of Cu or Cu alloy and glass frit is provided at both ends of the multilayer ceramic body, Ag A second conductive paste application step in which a conductive paste of an outermost electrode layer including a conductive metal material mainly composed of a -Pd alloy and glass frit is provided on the first conductive paste; And a baking step of forming a base electrode layer and an outermost electrode layer, and the thickness of the base electrode layer is set to 1 μm or more .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a multilayer ceramic electronic component and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.
[0017]
An embodiment of a multilayer ceramic electronic component and a manufacturing method thereof according to the present invention will be described with reference to FIG.
[0018]
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor 11 as an example of a multilayer ceramic electronic component according to the present invention, and a dielectric 12 ceramic printed with an internal electrode 13 using a base metal mainly composed of Ni or Ni alloy. The external connection terminal electrodes 15 are formed on both ends of the multilayer ceramic body 14 formed by sequentially laminating and firing the green sheets and cutting them into a plurality. Here, as the external connection terminal electrode 15, the glass frit was added to the metal powder mainly composed of Cu or Cu alloy so as to improve the familiarity with the internal electrode 13 and prevent the connection failure at the connection portion. A first conductive paste layer is applied, and a second conductive paste layer obtained by adding glass frit to a metal powder mainly composed of Ag or an Ag—Pd alloy is applied on the layer, and then the first conductive paste layer is formed. The paste layer and the second conductive paste layer are simultaneously baked at 700 ° C., and the base electrode layer 15a and the outermost electrode layer 15b are overlaid. That is, the base electrode layer 15a is formed of a baking layer having a thickness of 1 μm or more made of a conductive paint containing a conductive metal material mainly composed of Cu or Cu alloy and glass frit, and the outermost electrode layer 15b is made of Ag or Ag alloy. It is formed by the baking layer by the electrically conductive coating material containing the electrically conductive metal material which has as a main component, and glass frit. The base electrode layer 15a is preferably not thicker than necessary, and is preferably 3 μm or less.
[0019]
The baked base electrode layer 15 a is fused with the base metal of the internal electrode 13 exposed at both ends of the multilayer ceramic body 14 to form a Ni—Cu alloy layer 16 at the interface, and the base electrode layer 15 a The internal electrode 13 is in a good coupled state.
[0020]
As described above, in the present embodiment, in the multilayer ceramic electronic component in which the external connection terminal electrodes are formed at both ends of the multilayer ceramic body in which the internal electrode of the Ni or Ni alloy layer is provided, the external connection terminal electrode is Cu Alternatively, it is formed in a two-layer structure of a base electrode layer mainly composed of Cu alloy and an outermost electrode layer mainly composed of Ag or Ag-Pd, and the base electrode layer is a conductive material mainly composed of Cu or Cu alloy. The outermost electrode layer is formed of a conductive layer composed of a metal material and glass frit, and the outermost electrode layer is composed of a conductive metal material mainly composed of Ag or Ag-Pd and a conductive layer composed of glass frit. And a Cu-Ni alloy is formed at the interface between the Ni or Ni alloy layer of the internal electrode and the base electrode layer exposed at both ends of the multilayer ceramic body, and Since the external connection terminal electrode is a multilayer ceramic electronic component formed by co-baking the base electrode layer and the outermost electrode layer, when electrically energizing and fixing to the circuit board with lead (Pb) -free solder Achieving low-cost multilayer ceramic electronic components that can be applied to ultra-thin multilayer ceramic capacitors with external connection terminal electrodes with high heat cycle resistance that can prevent the effects of the resulting characteristics while maintaining the same electrical characteristics as conventional products. Is possible.
[0021]
Hereinafter, the present invention will be described in detail with reference to examples.
[0022]
【Example】
The following experiment was conducted in order to verify the appearance defect in the environmental atmosphere and the accompanying electric characteristic defect based on the difference in ionization tendency due to Ni of the internal electrode of the present invention and Cu of the base electrode layer.
[0023]
(Experiment 1)
20 monolithic ceramic capacitors according to an embodiment of the present invention and 20 conventional monolithic ceramic capacitors (with external connection terminal electrodes having a three-layer structure as shown in FIG. 2) were selected, and Ni for the internal electrode and Cu for the base electrode layer were selected. Based on the difference in ionization tendency due to the above, the appearance defect in the environmental atmosphere and the accompanying electrical characteristic failure were reduced to 0.90 μm (Example 1), 1.00 μm (Example 2), 1.10 μm (Example). Example 3) was verified by a conventional corrosive gas test (SO ₂ : 5 ppm × 240 hours), and the results are shown in Table 1 below.
[0024]
[Table 1]

In Table 1, Cp: capacitance, Tan δ: loss factor, IR: insulation resistance.
[0025]
From Table 1 above, it can be seen that if the Cu baking layer thickness of the base electrode layer is 1.00 μm or more, Cp, Tan δ and IR are good and there is no precipitate such as Ni sulfide, which is equivalent to the conventional product. In particular, as in Example 1, when the layer thickness is thin, Ni of the internal electrode is ionized and deposited as Ni sulfide on the internal electrode layer and the outside, causing deterioration of electrical characteristics. On the other hand, as in Example 2 and Example 3, when the layer thickness is 1.00 μm or more, it reacts further with the Ni sulfide at the firing temperature, that is, Ag—Pd formed on the layer is reduced. It can be inferred that Cu—Ni alloy joints are formed at the interface between the Ni layer where the internal electrode is exposed and the underlying electrode layer of Cu serving as a medium to strengthen the alternating contact and improve the conductivity.
[0026]
Therefore, in the conventional case, a formation process such as plating was required to form the external connection terminal electrode. However, the formation process such as plating can be saved, and it can be prevented from being a complicated process. Therefore, it can be manufactured at a low cost.
[0027]
(Experiment 2)
Next, 100 multilayer ceramic capacitors of Example 1, Example 2 and Example 3 were selected, the number of cracks after heat cycle test and the heat resistance against Pb-free soldering were verified, and the results were as follows: It shows in Table 2.
[0028]
[Table 2]

As shown in Table 2 above, no crack was generated and the heat resistance was good when the thickness of the Cu layer as the base electrode layer was 1.00 μm or more, and good results were obtained. If the thickness is less than 1.00 μm, the heat resistance is inferior, that is, the heat resistance is inferior, that is, cavitation occurs due to precipitation of sulfides, shrinkage occurs during cooling (room temperature 25 ° C.), and cracks occur in the heat cycle test. Although the number of cracks generated is small, it is easy to judge, but in mass production, a large defect rate is induced, leading to a decrease in production yield.
[0029]
Therefore, it is necessary to increase the thickness of the Cu layer film, which is the base electrode layer, from the viewpoint of heat resistance, but considering the high tension and compressive force, it is sufficient to ensure the minimum thickness that can maintain heat resistance. It can be seen that a range of at least 1.00 μm is sufficient. The base electrode layer is preferably not thicker than necessary, and is preferably 3 μm or less.
[0030]
Although the embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims.
[0031]
【The invention's effect】
As described above, according to the present invention, when external connection terminal electrodes are formed on both ends of a multilayer ceramic body having internal electrodes of Ni or Ni alloy layers, the external connection terminal electrodes are Cu or Cu. Since it is formed of a multilayer of an underlayer electrode layer mainly composed of an alloy and an outermost electrode layer mainly composed of Ag or an Ag alloy, when electrically energizing and fixing to a circuit board with lead (Pb) -free solder Thus, the external connection terminal electrode having high heat cycle resistance can be formed. In addition, it is possible to save labor in the formation process such as plating, prevent a complicated process, and manufacture at a low cost. As a result, it is possible to realize a multilayer ceramic electronic component that can be applied to an extremely small multilayer ceramic capacitor or the like while maintaining the same electrical characteristics as a conventional product and at a low cost.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing an embodiment of a multilayer ceramic electronic component according to the present invention.
FIG. 2 is a front sectional view of a conventional multilayer ceramic electronic component.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,11 Multilayer ceramic capacitor 2,12 Dielectric body 3,13 Internal electrode 4,14 Multilayer ceramic body 5,15 External connection terminal electrode 5a First electrode layer 5b Second electrode layer 5c Third electrode layer 15a Base electrode layer 15b Outermost electrode layer 16 Alloy layer

Claims (2)

In a multilayer ceramic electronic component in which external connection terminal electrodes are formed at both ends of a multilayer ceramic body in which internal electrodes of Ni or Ni alloy layers are provided,
The external connection terminal electrode is formed of two layers of a base electrode layer mainly composed of Cu or Cu alloy and an outermost electrode layer mainly composed of Ag—Pd alloy,
The base electrode layer is formed by a baking layer made of a conductive paint containing a conductive metal material mainly composed of Cu or Cu alloy and glass frit,
The outermost electrode layer is formed at the same time as the base electrode layer with a baking layer made of a conductive paint containing a conductive metal material mainly composed of an Ag—Pd alloy and glass frit,
Cu-Ni alloy is formed at the interface between the Ni or Ni alloy layer of the internal electrode and the base electrode layer exposed at both ends of the multilayer ceramic body ,
A multilayer ceramic electronic component , wherein the base electrode layer has a thickness of 1 μm or more . In a method for manufacturing a multilayer ceramic electronic component in which external connection terminal electrodes are formed at both ends of a multilayer ceramic body in which internal electrodes of Ni or Ni alloy layers are provided,
The manufacturing process of the external connection terminal electrode comprises:
A first conductive paste application step of providing a conductive paste of a base electrode material including a conductive metal material mainly composed of Cu or Cu alloy and glass frit at both ends of the multilayer ceramic body;
A second conductive paste coating step in which a conductive paste of an outermost electrode layer containing a conductive metal material mainly composed of an Ag-Pd alloy and glass frit is provided on the first conductive paste;
A baking step of simultaneously baking the first and second conductive pastes to form a base electrode layer and an outermost electrode layer; and
A method for manufacturing a multilayer ceramic electronic component, wherein the thickness of the base electrode layer is 1 μm or more .

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