JPH10251837A - Electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electronic parts with least deterioration of solder wettability having an external electrode and capable of being easily stored. SOLUTION: An external electrode 4 having a multilayer structure is used, its outermost electrode layer 4c is a thin-film electrode layer (to be wetted with solder) consisting of a metal with palladium as the main component, and a thin-film layer consisting of nonmagnetic nickel(Ni) alloy is used as the lower electrode layer 4b (solder heat-resistant layer). Further, the outermost electrode layer is obtained by forming the film of Pd or a Pd-Au alloy by physical vapor deposition aggregation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electronic component,
More specifically, the present invention relates to an electronic component having an external electrode provided on a surface of an element.

[0002]

2. Description of the Related Art For example, as shown in FIG. 3, a chip type (surface mount type) multilayer ceramic capacitor includes a plurality of internal ceramic elements 31 in a ceramic element 31 with a ceramic layer 33 interposed therebetween. While the electrodes 32 are laminated, external electrodes 34, which are electrically connected to the internal electrodes 32 alternately drawn to the opposite sides, are provided on both ends of the ceramic element 31.
34 is provided.

In recent years, the external electrodes 34 have been formed by a so-called dry plating method such as sputtering or vapor deposition. Specifically, for example, a fixed electrode layer (for example, a chromium (Cr) layer) 34a for securing the fixing property to the ceramic element 31 and a fixed electrode layer for securing the resistance to high temperature during soldering in the mounting process. A solder heat resistant layer (for example, a nickel (Ni) layer) 34b formed on the solder heat resistant layer 34b and a solder wettable layer (for example, a silver (Ag) layer or gold) formed on the solder heat resistant layer 34b to secure solder wettability. (Au) layer, A
a three-layer structure consisting of 34c is proposed,
It has been implemented.

As an application, a solder wetting layer is
As a two-layer structure including an initial solder wetting layer (eg, an Ag layer) and a solder wettability deterioration preventing layer (eg, a tin (Sn) layer), a four-layer structure as a whole, or a single layer having a plurality of functions Is considered to have a two-layer structure as a whole. As a whole having a four-layer structure, for example, as disclosed in JP-A-5-29176, a chromium electrode layer is formed as a fixed electrode layer, and Ni, Cu, An electrode layer made of an alloy of the above is formed, and an electrode layer made of Sn, Ag, an Ag alloy, a solder alloy, etc. is formed as a solder wetting layer, and a solder alloy, Sn, Sn alloy, etc. is made as a solder wetting deterioration preventing layer. Some have an electrode layer formed.

However, since Ni, which is generally used as a solder heat-resistant layer, has magnetic properties, it is difficult to form a film by a magnetron sputtering method widely used industrially, and the efficiency is low. There is.

Therefore, conventionally, copper (Cu), chromium (Cr), molybdenum (Mo), titanium (Ti),
Vanadium (V), aluminum (Al), silicon (S
i) and the like (hereinafter collectively referred to as “non-magnetizing metal”) are added to make Ni non-magnetic.

On the other hand, the thickness of a solder wetting layer such as an Ag layer, an Au layer, and an Ag alloy layer formed on a solder heat-resistant layer is usually about several μm, and the initial solder wettability is sufficient. When stored for a long period of time or left at a high temperature, there is a problem that the non-magnetic material in the solder heat-resistant layer diffuses into the solder wetting layer and deteriorates the solder wettability.

Further, the Sn layer used as a layer for preventing the deterioration of solder wettability in the conventional external electrode has low moisture resistance, causing deterioration in characteristics by a moisture resistance test, or reacting with the lower electrode layer to improve solderability. There is a problem in that an intermetallic compound having poor resistance is formed.

An object of the present invention is to solve the above-mentioned problems and to provide an electronic component which has less deterioration in solder wettability, has external electrodes excellent in moisture resistance, and is easy to store. And

[0010]

In order to achieve the above object, an electronic component according to the present invention is an electronic component having an external electrode disposed on an element surface, wherein the external electrode is formed of a plurality of electrode layers. And the outermost electrode layer constituting the external electrode is a thin film electrode layer containing palladium (Pd) as a main component, and the lower electrode layer in contact with the outermost electrode layer is made of a non-magnetic nickel (Ni) alloy. Characterized by a thin film electrode layer made of

When the thin film electrode layer made of a metal mainly composed of Pd is used as the outermost electrode layer and the thin film electrode layer made of a non-magnetic nickel alloy is used as the lower electrode layer, the lower electrode layer moves from the lower electrode layer to the outermost electrode layer. Suppress and prevent the diffusion of non-magnetic metal
Deterioration of solder wettability can be prevented, and since palladium has excellent moisture resistance, it is possible to improve the moisture resistance of the entire external electrode. In addition, since the thin-film electrode made of a non-magnetic Ni alloy is used as the lower electrode layer, it has excellent solder heat resistance, and it is possible to use industrially mass-produced magnetron sputtering, thereby reducing manufacturing costs. Can be. In the electronic component of the present invention, there is no particular limitation on the type of the fixed electrode layer for securing the fixation to the element. Various electrode layers can be used as fixed electrode layers.

Further, in the electronic component according to the present invention, the outermost electrode layer is preferably made of palladium (Pd) or palladium (Pd).
-It is characterized by being a thin film electrode layer formed by depositing a gold (Au) alloy by a physical vapor deposition aggregation method.

By forming a film of Pd or a Pd-Au alloy by a physical vapor deposition aggregation method, the outermost electrode layer, which is a thin film electrode layer, can be formed efficiently, and the present invention can be more effectively performed. It becomes possible to tighten. In addition, as the physical vapor deposition aggregation method, a sputtering method, a vapor deposition method, and the like are exemplified, but various other methods can be used.

Further, in the electronic component of the present invention, the thin film electrode layer made of the Ni alloy has a structure in which copper (Cu), chromium (Cr), molybdenum (Mo), titanium (Ti), Vanadium (V), aluminum (A
1) a thin film electrode layer formed by magnetron sputtering a nickel alloy made non-magnetic by adding at least one selected from the group consisting of silicon (Si).

Cu, Cr, Mo, Ti, V, Al, Si
By using at least one selected from the group consisting of as the non-magnetizing metal, it is possible to reliably demagnetize Ni, and it is possible to efficiently form Ni into a film by magnetron sputtering. External electrodes can be formed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described, and features thereof will be described in more detail.

[Embodiment 1] In this embodiment, a chip type multilayer ceramic capacitor as shown in FIG. 1 will be described as an example. As shown in FIG. 1, this chip type (surface mount type) multilayer ceramic capacitor includes a plurality of internal electrodes 2 in a ceramic element 1 via a ceramic layer 3.
And external electrodes 4 and 4 that are electrically connected to the internal electrodes 2 alternately drawn to the opposite sides are disposed on both ends of the ceramic element 1.

The external electrode 4 is connected to the ceramic element 1
The fixed electrode layer 4a for securing the fixability to the solder, and the solder heat resistant layer 4 formed on the fixed electrode layer 4a for securing the resistance to the high temperature during soldering in the mounting process.
b and solder heat resistant layer 4 to ensure solder wettability
b has a three-layer structure composed of a solder wetting layer 4c formed on the substrate b.

[Formation of External Electrodes] A multilayer ceramic capacitor element is mounted on a jig, and fixed by sputtering. Fixed electrode layer: Ti electrode layer having a thickness of 0.1 μm Solder heat resistant layer: NiCu having a thickness of 0.5 μm (Cu: 30)
%) Electrode layer Solder wet layer: An external electrode having a three-layer structure (Example 1) was formed by forming a thin film serving as a Pd electrode layer having a thickness of 0.2 μm.

The film forming conditions are as follows. Substrate temperature: 150 ° C. Degree of vacuum: 1 × 10 ⁻³ Torr Gas: Argon Method: DC sputtering

For comparison, a fixed electrode layer: a 0.1 μm thick Ti electrode layer, a solder heat resistant layer: a 0.5 μm thick NiCu (Cu: 30
%) Electrode layer Solder wetting layer: Ag electrode layer having a thickness of 0.7 μm (however, the film formation time of the solder wetting layer (Ag electrode layer): 0.1%).
5A for 11 minutes) and a three-layered external electrode (Comparative Example 1) and a fixed electrode layer: a 0.1 μm-thick Ti electrode layer; a solder heat-resistant layer: a 0.5 μm-thick NiCu (Cu: 30
%) Electrode layer Solder wetting layer: Au electrode layer having a thickness of 0.7 μm (however, the film forming time of the solder wetting layer (Au electrode layer): 0.
5A for 14 minutes) to form a three-layer external electrode (Comparative Example 2). The film forming conditions (substrate temperature, degree of vacuum, type of gas, and method) other than the film forming time are the same as those in the first embodiment.

[Evaluation] Next, in order to examine the weather resistance of each sample (multilayer ceramic capacitor), a high-temperature standing test at 150 ° C. for 96 hours was performed, and then the solder wettability was evaluated. Table 1 shows the results.

[0023]

[Table 1]

The evaluation of the solder wettability in Table 1 is based on the evaluation of the solder wettability when the ratio of the adhesion area to the external electrode area (adhesion area / external electrode area) exceeds 90%. Is good (○), 65 to 9
A range of 0% was judged to be slightly poor in solderability (△), and a case of less than 65% was judged to be poor in solder wettability (X).

According to Table 1, in the case of Comparative Example 1 in which the outermost electrode layer (solder wetting layer) was an Ag electrode, the solder wettability was poor after 24 hours, and the outermost electrode layer was an Au electrode. In Comparative Example 2, the solderability was slightly poor after 24 hours, and poor after 96 hours. On the other hand, in Example 1, solder wettability was observed after 96 hours. The properties were good.

When the surface of the sample after standing for 96 hours was examined by X-ray photoelectron spectroscopy (XPS), the surface of the Ag electrode (Comparative Example 1) and the surface of the Au electrode (Comparative Example 2) showed Cu
Was diffused to form copper oxide, which was a cause of deteriorating solder wettability. In the above embodiment, since the nonmagnetic NiCu containing 30% of Cu is used for the solder heat-resistant layer, film formation by magnetron sputtering was possible.

[Embodiment 2] In this embodiment, a plate-shaped ceramic capacitor will be described as an example. As shown in FIG. 2, this plate-shaped ceramic capacitor has external electrodes 12, 12 as capacitance electrodes disposed on both front and back surfaces of a plate-shaped ceramic element 11, and lead terminals 13, 13 on the external electrode 12. It has an attached structure. In the present invention, functional electrodes such as the external electrodes 12 are collectively referred to as external electrodes.

The external electrodes 12 are, in order from the ceramic element 11 side, a fixed electrode layer 12a for securing adhesion to the ceramic element 11, and a solder for securing resistance to high temperatures during soldering in a mounting process. It is formed by forming a heat resistant layer 12b and a solder wet layer 12c for ensuring solder wettability.

[Formation of External Electrodes] A plate-shaped ceramic capacitor element is mounted on a jig, and fixed by sputtering. Fixed electrode layer: Ti electrode layer having a thickness of 0.1 μm Solder heat-resistant layer: NiCr having a thickness of 0.5 μm (Cr: 10
%) Electrode layer Solder wet layer: An external electrode having a three-layer structure (Example 2) was formed by forming a thin film serving as a Pd electrode layer having a thickness of 0.2 μm.

The film forming conditions are as follows. Substrate temperature: 150 ° C. Degree of vacuum: 1 × 10 ⁻³ Torr Gas: Argon Method: DC sputtering

For comparison, a fixed electrode layer: a 0.1 μm-thick Ti electrode layer, a solder heat-resistant layer: a 0.5 μm-thick NiCr (Cr: 10
%) Electrode layer Solder wetting layer: Ag electrode layer having a thickness of 0.7 μm (however, the film formation time of the solder wetting layer (Ag electrode layer): 0.1%).
5A for 11 minutes) and a three-layer external electrode (Comparative Example 3) and a fixed electrode layer: a 0.1 μm thick Ti electrode layer; a solder heat resistant layer: a 0.5 μm thick NiCr (Cr: 10
%) Electrode layer Solder wetting layer: Au electrode layer having a thickness of 0.7 μm (however, the film forming time of the solder wetting layer (Au electrode layer): 0.
5A for 14 minutes) to form a three-layered external electrode (Comparative Example 4). The film forming conditions (substrate temperature, degree of vacuum, type of gas, and method) other than the film forming time are the same as those in the second embodiment.

[Evaluation] Next, in order to examine the weather resistance of each sample (plate-like ceramic capacitor), a high-temperature standing test at 150 ° C. for 96 hours was performed, and then the solder wettability was evaluated. Table 2 shows the results.

[0033]

[Table 2]

The evaluation criteria for the solder wettability in Table 2 are as shown in Table 1.
Is the same as From Table 2, in the case of Comparative Example 3 in which the outermost electrode layer (solder wetting layer) was an Ag electrode, the solder wettability was poor after 24 hours, and the outermost electrode layer was an Au electrode. In the case of Example 4, the solderability was slightly poor after 24 hours and was poor after 96 hours, whereas in Example 2, the solder wettability was good even after standing for 96 hours. Met.

When the surface of the sample after standing for 96 hours was examined by X-ray photoelectron spectroscopy (XPS), the surface of the Ag electrode (Comparative Example 3) and the surface of the Au electrode (Comparative Example 4) showed Cr.
Was diffused, which was a cause of deterioration of solder wettability. In the above embodiment, since non-magnetic NiCr containing 10% of Cr is used for the solder heat resistant layer, film formation by magnetron sputtering was possible.

[Embodiment 3] In this embodiment, a multilayer ceramic capacitor having a structure similar to that of FIG. 1 will be described as an example (not shown). [Formation of External Electrodes] A multilayer ceramic capacitor element was mounted on a jig, and fixed by sputtering. Fixed electrode layer: Cr electrode layer having a thickness of 0.5 μm Solder heat resistant layer: NiCu having a thickness of 0.5 μm (Cu: 30)
%) Electrode layer Solder wetting layer: An external electrode having a three-layer structure (Example 3) was formed by forming a thin film serving as a Pd electrode layer having a thickness of 0.2 μm.

The film forming conditions are as follows. Substrate temperature: 150 ° C. Degree of vacuum: 1 × 10 ⁻³ Torr Gas: Argon Method: DC sputtering

For comparison, a fixed electrode layer: a 0.5 μm thick Cr electrode layer, a solder heat resistant layer: a 0.5 μm thick NiCu (Cu: 30
%) Electrode layer Solder wetting layer: Sn electrode layer having a thickness of 0.7 μm (however, the film formation time of the solder wetting layer (Sn electrode layer): 0.
5A for 20 minutes) to form a three-layer external electrode (Comparative Example 5). The film forming conditions (substrate temperature, degree of vacuum, type of gas, and method) other than the film forming time are the same as those in the third embodiment.

For comparison, a fixed electrode layer: a 0.5 μm thick Cr electrode layer, a solder heat resistant layer: a 0.5 μm thick NiCu (Cu: 30
%) Electrode layer Solder wetting layer: Ag electrode layer having a thickness of 0.7 μm (however, the film formation time of the solder wetting layer (Ag electrode layer): 0.1%).
5A for 11 minutes) to form a three-layered external electrode (Comparative Example 6). The film forming conditions (substrate temperature, degree of vacuum, type of gas, and method) other than the film forming time are the same as those in the third embodiment.

[Evaluation] Next, in order to examine the weather resistance of each sample (multilayer ceramic capacitor), a high-temperature standing test at 150 ° C. for 96 hours was performed, and then the solder wettability was evaluated. Table 3 shows the results.

[0041]

[Table 3]

The criteria for evaluation of the solder wettability in Table 3 are as shown in Table 1.
Is the same as From Table 3, it can be seen that in each of Comparative Example 5 in which the outermost electrode layer (solder wetting layer) is an Sn electrode and Comparative Example 6 in which an Ag electrode is used, the solder wettability is poor after 24 hours. On the other hand, in the case of Example 3, the solder wettability was good even after being left for 96 hours.

When the sample after standing for 96 hours was analyzed by X-ray photoelectron spectroscopy (XPS) in the depth direction from the surface of the sample, in the sample of Comparative Example 5, Sn forming the solder wetting layer was not found. , Ni constituting the solder heat resistant layer
It was confirmed that the metal compound diffused into Cu to form a metal compound having poor solder wettability, which was a cause of poor soldering. In the above embodiment, Cu3
Since nonmagnetic NiCu containing 0% was used, film formation by magnetron sputtering was possible.

[Embodiment 4] In this embodiment, a multilayer ceramic capacitor having a structure similar to that of FIG. 1 will be described as an example (not shown). [Formation of External Electrodes] A multilayer ceramic capacitor element was mounted on a jig, and fixed by sputtering. Fixed electrode layer: Cr electrode layer having a thickness of 0.5 μm Solder heat resistant layer: NiCu having a thickness of 0.5 μm (Cu: 30)
%) Electrode layer Solder wet layer: An external electrode having a three-layer structure (Example 4) was formed by forming a thin film serving as a Pd electrode layer having a thickness of 0.2 μm.

The film forming conditions are as follows. Substrate temperature: 150 ° C. Degree of vacuum: 1 × 10 ⁻³ Torr Gas: Argon Method: DC sputtering

For comparison, a fixed electrode layer: a thick Ag electrode layer having a thickness of 80 μm, a solder heat-resistant layer: an electroplated Ni electrode layer having a thickness of 3.6 μm, and a solder wetting layer: an electroplated Sn electrode layer having a thickness of 3.6 μm. (Comparative Example 7) was formed.

[Evaluation] Next, in order to examine the weather resistance of these multilayer ceramic capacitors, the temperature was set to 100 ° C. and RH10.
It was left in a 0%, 12-hour wet condition, and then the solder wettability was evaluated. Table 4 shows the results.

[0048]

[Table 4]

The evaluation criteria for the solder wettability in Table 4 are as shown in Table 1.
Is the same as According to Table 4, in the case of Comparative Example 7 in which the Sn plating layer (the electroplated Sn electrode layer) was used as the solder wetting layer, the solder wettability was slightly poor after 8 hours, and after 12 hours, the solder wettability was poor. Poor wettability. On the other hand, in the case of Example 4, the solder wettability was good even after standing for 12 hours.

When the surface of the sample after standing for 12 hours was analyzed by X-ray photoelectron spectroscopy (XPS), in the case of Comparative Example 7, Sn constituting the solder wetting layer became hydroxide, It was confirmed that this was a cause of deteriorating solder wettability. In the above embodiment, since nonmagnetic NiCu containing 30% of Cu is used for the solder heat-resistant layer, film formation by magnetron sputtering was possible.

In each of the above embodiments, a multilayer ceramic capacitor and a plate-like ceramic capacitor have been described as examples. However, the present invention is not limited to ceramic capacitors, but includes resistance components such as varistors, piezoelectric resonance components, semiconductor devices, and LC composite capacitors. The present invention can be applied to various electronic components having components and other external electrodes.

In the above embodiment, the electronic component having the three-layered external electrode has been described as an example.
The present invention is not limited to electronic components having external electrodes having a three-layer structure, but can be applied to electronic components having a multilayer structure of four or more layers.

In the above embodiment, the outermost electrode layer is made of P
Although the case of the d thin film electrode has been described as an example, Pd-
It is also possible to use a thin film electrode containing Pd such as Au alloy as the outermost electrode layer.

In other respects, the present invention is not limited to the above-described embodiment. Specific types of the physical vapor deposition aggregation method for forming the outermost electrode layer and each electrode constituting the external electrode Regarding the thickness of the layer, the type of non-magnetizing metal added to Ni, etc., within the scope of the invention,
Various applications and modifications are possible.

[0055]

As described above, the electronic component of the present invention has a P
Since the thin film electrode layer made of a metal containing d as a main component is used as the outermost electrode layer and the thin film electrode layer made of a non-magnetic Ni alloy is used as the lower electrode layer, the lower electrode layer is not connected to the outermost electrode layer. It is possible to suppress and prevent the diffusion of the magnetized metal to prevent the deterioration of the solder wettability, and the metal composed mainly of Pd constituting the outermost electrode layer has excellent moisture resistance. In addition, the moisture resistance of the entire external electrode can be improved. In addition, since the thin-film electrode made of a non-magnetic Ni alloy is used as the lower electrode layer, it has excellent solder heat resistance, and it is possible to use industrially mass-produced magnetron sputtering, thereby reducing manufacturing costs. Can be.

In forming the outermost electrode layer,
When palladium (Pd) or a palladium (Pd) -gold (Au) alloy is formed by a physical vapor deposition aggregation method, the outermost electrode layer can be efficiently formed. It can be more effective.

The non-magnetic Ni constituting the lower electrode layer
Copper (Cu), chromium (C
r), by using at least one member selected from the group consisting of molybdenum (Mo), titanium (Ti), vanadium (V), aluminum (Al), and silicon (Si), to reliably demagnetize Ni. And the film can be formed by magnetron sputtering, and the external electrode can be formed industrially efficiently.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an electronic component (multilayer ceramic capacitor) according to an embodiment of the present invention.

FIG. 2A is a perspective view showing an electronic component (plate-shaped ceramic capacitor) according to another embodiment of the present invention, and FIG.
Is a sectional view.

FIG. 3 shows a conventional electronic component (multilayer ceramic capacitor).
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic element 2 Internal electrode 3 Ceramic layer 4 External electrode 4a Fixed electrode layer 4b Solder heat resistant layer 4c Solder wet layer 11 Plate-shaped ceramic element 12 External electrode 12a Fixed electrode layer 12b Solder heat resistant layer 12c Solder wet layer 13 Lead terminal

Claims (3)

[Claims] 1. An electronic component having an external electrode disposed on an element surface, wherein the external electrode is formed of a plurality of electrode layers, and an outermost electrode layer constituting the external electrode is palladium (P).
An electronic component, comprising: d) a thin film electrode layer as a main component, wherein the lower electrode layer in contact with the outermost electrode layer is a thin film electrode layer made of a non-magnetic nickel (Ni) alloy. 2. The method according to claim 1, wherein the outermost electrode layer comprises palladium (Pd);
The electronic component according to claim 1, wherein the electronic component is a thin film electrode layer formed by depositing a palladium (Pd) -gold (Au) alloy by a physical vapor deposition aggregation method. 3. The method according to claim 1, wherein the thin film electrode layer made of the Ni alloy is made of copper (Cu), chromium (Cr), nickel (Ni).
A magnetron sputtering method is applied to a nickel alloy demagnetized by adding at least one selected from the group consisting of molybdenum (Mo), titanium (Ti), vanadium (V), aluminum (Al), and silicon (Si). 2. The electronic component according to claim 1, wherein the electronic component is a thin-film electrode layer formed by the following method.