JP2003303736A - Electronic component with outer metal terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component that has large tensile strength between the terminal electrode and the outer metal terminals, i.e., has strong adhesion, and is superior in reflow soldering and in environmental distribution measures without containing lead. <P>SOLUTION: This electronic component with outer metal terminals is characterized in that the terminal electrodes 12 of a ceramic capacitor element 1 are electrically connected through a solder layer 5 to the outer metal terminals 3 and the conductive content in the terminal electrode 12 diffuses into the solder layers 4, 5 and forms a diffused layer 5 μm thick or thicker when the terminal electrodes 12 are connected to the outer metal terminals 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component with an external metal terminal such as a composite type multilayer capacitor.

[0002]

2. Description of the Related Art Generally, an electronic component such as a composite type multilayer capacitor is provided with an external metal terminal joined to an end electrode for electrical connection with a circuit board or the like. As a method of joining the external metal terminal of such an electronic component to a circuit board or the like, a soldering method is often used.
The external metal terminal of the electronic component has solder heat resistance because it is mounted on the circuit board using solder.
It also has solder wettability.

The structure of the external metal terminal described above is formed by applying paste to the material of the external metal terminal and baking it.
A base electrode made of u or the like is provided, and nickel plating is performed to provide solder heat resistance, and tin plating is provided to provide solder wettability. Then, conventionally, these plated layers and the end electrodes of the electronic component are joined by soldering.

[0004]

By the way, in recent years, measures for environmental problems have come to be emphasized.
Lead contained in solder, which has been frequently used, is also a problem. For this reason, lead-free solders have come to be used, and electronic parts are also being joined to external metal terminals using lead-free solder and further mounted on circuit boards and the like.

However, for electronic parts such as composite type multilayer capacitors and circuit modules, high temperature solder is generally used when soldering is used. In this case, the current situation is that sufficient materials have not been obtained due to problems such as bonding strength.

That is, the conventional solder joint between the electronic component and the external metal terminal is located outside the nickel plating formed for heat resistance of the external metal terminal (on the electronic component side).
However, the bonding strength between the electronic component and the external metal terminal was not sufficient, and there was a problem in practical use.

The present invention has been made in view of the above circumstances, and has a large tensile strength between the end electrodes and the external metal terminals, that is, a high bonding strength and an excellent reflowability.
Further, the present invention provides a joint structure of electronic components which does not contain lead and which is also suitable for environmental problems, and an electronic component with an external metal terminal having such a joint structure.

[0008]

The invention according to claim 1 is
In an electronic component with an external metal terminal, when electrically connecting the end electrode of the electronic component body and the external metal terminal via a solder layer, and when joining the end electrode of the electronic component body and the external metal terminal In addition, the conductive component of the end electrode of the electronic component body diffuses into the solder layer, and a diffusion layer having a thickness of 5 μm or more is formed at the solder joint portion.

According to the invention of claim 1, since the diffusion layer having a thickness of 5 μm or more is formed in the solder layer for joining the end electrode and the external metal terminal, the end electrode and the external metal terminal are formed. It is possible to obtain a high-quality electronic component with an external metal terminal that is excellent in tensile strength between.

According to a second aspect of the present invention, in the electronic component with an external metal terminal according to the first aspect, the solder layer is made of Sn-Sb type high temperature solder having a solidus temperature of 230 ° C. or higher. The end electrode of the main body is characterized in that Cu is the main component, and the metal component diffused in the solder layer is Cu.

According to the second aspect of the invention, since the diffusion layer having a metal component of Cu is formed in the solder layer made of Sn—Sb type high temperature solder for joining the end electrode and the external metal terminal, It is possible to obtain a high-quality electronic component with an external metal terminal that is excellent in tensile strength, has a high solidus temperature, is excellent in reflow resistance, and does not contain lead because it does not contain environmental pollution.

According to a third aspect of the present invention, in the electronic component with an external metal terminal according to the first or second aspect, the end electrode of the electronic component body has a conductive component as a main component of Cu, and the end face of the end electrode. Is plated with Ni, and Cu diffused into the solder layer diffuses through the Ni plated layer.
It is characterized in that a diffusion layer is formed in the solder layer portion.

According to the third aspect of the present invention, since the Cu diffusion layer through the Ni plating layer is formed in the solder layer joining the end electrode and the external metal terminal, the first aspect of the present invention is described. Similar to the invention, it is possible to obtain a high-quality electronic component with an external metal terminal which is excellent in tensile strength between the end electrode and the external metal terminal.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

FIG. 1 is a front view of a composite multilayer capacitor which is a component with external metal terminals according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of the composite multilayer capacitor shown in FIG.

The composite type multilayer capacitor shown in FIGS. 1 and 2 is, for example, a rectangular parallelepiped ceramic capacitor element 1 which is an electronic component body, and the ceramic capacitor element 1.
It has a pair of external metal terminals 2 and 3 joined to.
The ceramic capacitor element 1 is provided with end electrodes 11 and 12 on both end surfaces facing each other in the direction of the length L.

As shown in FIG. 2, the ceramic capacitor element 1 has a large number (for example, 100 layers) of internal electrodes 101 and 102 inside a ceramic dielectric substrate 100. One end of the internal electrode 101 is connected to the end electrode 11,
The other end is an open end, one end of the internal electrode 102 is connected to the end electrode 12, and the other end is an open end. The constituent materials of the end electrodes 11 and 12, the internal electrodes 101 and 102, the ceramic dielectric substrate 100, and the manufacturing method thereof are well known.

The external metal terminal 2 has one end 21 joined (connected) to the end electrode 11 and has a folded-back portion 22 at an intermediate portion. The protruding end side of the folded-back portion 22 is bent into an L shape to be externally connected. The terminal portion 23 is connected to a conductor (circuit board or the like).

The external metal terminal 3 also has one end 31 joined to the end electrode 12 and a folded-back portion 32 at an intermediate portion. The protruding end side of the folded-back portion 32 is bent in an inverted L shape to form an external conductor ( The terminal portion 33 is connected to a circuit board or the like).

The material of the external metal terminals 2 and 3 is formed of a material having low electric resistance and excellent spring property. A plate material of phosphor bronze is a typical example of the material. The plate thickness is not particularly limited, but is typically 0.1 m.
It is about m.

One ends 21, 31 of the external metal terminals 2, 3
Are solder layers 4 and 5 made of solder, each of which will be described in detail later.
Are joined to the end faces of the end electrodes 11 and 12.

FIG. 3 is a partial sectional view showing a state in which the composite type multilayer capacitor shown in FIGS. 1 and 2 is mounted on the circuit board 70. This composite type multilayer capacitor is mounted, for example, on the circuit board 70 via solder 81. Conductor patterns 71 and 72 are provided on the surface of the circuit board 70. The terminal portion 23 of the external metal terminal 2 provided in the composite type multilayer capacitor is formed by the solder 81 into the conductor pattern 7
1 is soldered to the external metal terminal 3
3 is also soldered to the conductor pattern 72 by the solder 81.

In the present embodiment, when the solder layer 5 is formed, a high temperature lead-free solder that does not melt or is difficult to melt (that is, has reflow resistance) at a reflow temperature of 200 ° C. or higher is used. . As the high temperature lead-free solder, specifically, the metal composition is Sn-Sb system, and Sn / Sb has a weight% ratio of, for example, 90/10, a solidus line of 230 ° C or higher, and a liquidus line of 268 ° C Is preferred.

Similarly, the terminal portion 23 of the external metal terminal 2
And the conductor pattern 71, and the solder 8 used for soldering the terminal portion 33 of the external metal terminal 3 and the conductor pattern 72, respectively.
1 can also use the above-mentioned high temperature lead-free solder.

Next, a joining structure of the end electrode 12 using the solder layer 5 of the present embodiment and the one end 31 of the external metal terminal 3 (the other end electrode 11 and the one end 2 of the external metal terminal 2).
The same applies to the joint structure with 1) with reference to FIG.

As shown in FIG. 4, the end electrodes 12 are made of Cu.
Is used as a main component, a nickel (Ni) plating layer 42 for providing solder heat resistance, and a tin (Sn) plating layer 43 for providing solder wettability.

Then, the end electrode 12 and the one end 31 of the external metal terminal 3 are joined by the solder layer 5 which is the Sn—Sb type high temperature lead-free solder. The tin-plated layer 43 is in a state of diffusively mixed with the solder layer 5 which is a Sn—Sb-based high temperature lead-free solder during heating for soldering.

That is, when the bonding structure of this embodiment is specifically described, from the left side of FIG. 4, the ceramic capacitor element 1, the base electrode 12a, the nickel plating layer 42, the tin plating layer 43, and the Sn—Sb system high temperature lead-free. The solder 5 and the one end 31 of the external metal terminal 3 are arranged in this order. Here, the end electrodes 1 of the four types of composite type multilayer capacitors configured by performing the reflow process in the reflow furnace using the above-mentioned high temperature lead-free solder
Regarding samples 1 to 12 and external metal terminals 2 and 3 (samples 1 to 4), temperature conditions (atmosphere temperature) during reflow in the reflow furnace, passage time conditions, and known EPM
The Cu component solder diffusion layer 45 around the base electrode 12a analyzed by A will be described with reference to FIGS. 6A to 6D show the solder diffusion layer 45.
3 schematically shows the structure of the solder diffusion layer 45 generated in the sample 1 and the samples 2 to 4 in which the solder does not occur.

In the case of sample 1, the solder diffusion layer 4 was formed under the temperature condition of 325 ° C. and the passing time condition of 5 minutes as shown in FIG. 6 (A).
5 was not found.

In the case of Sample 2, under the temperature condition of 325 ° C. and the furnace time condition of 7 minutes, the solder diffusion layer 45 having a thickness of 5 to 10 μm is introduced into the solder layer 5 through the nickel plating layer 42 as shown in FIG. 6B. (Indicated by cross hatching) occurred.

In the case of Sample 3, under the temperature condition of 350 ° C. and the furnace time condition of 5 minutes, the solder diffusion layer 45 having a thickness of 5 to 20 μm is introduced into the solder layer 5 through the nickel plating layer 42 as shown in FIG. 6C. (Indicated by cross hatching) occurred.

In the case of Sample 4, under the temperature condition of 350 ° C. and the passing time condition of 7 minutes, the solder diffusion layer 45 having a thickness of 5 to 40 μm is introduced into the solder layer 5 through the nickel plating layer 42 as shown in FIG. 6D. (Indicated by cross hatching) occurred.

The joining structure between the end electrode 11 of each of the samples 1 to 4 and the one end 21 of the external metal terminal 2 was similar to that described above.

Next, with respect to the above-mentioned Samples 1 to 4, the judgment results of the tensile strength by the tensile strength test will be described.

The tensile strength test is as shown in FIG.
Using the piano wire 51, the terminal portions 23 and 33 of the external metal terminals 2 and 3 of each of the samples 1 to 4 are opened to the outside, and the piano wire 51 bent in a key shape is provided in the holes of the external metal terminals 2 and 3. It is hooked on a part and the tensile strength is measured by a normal tensile strength tester.

As a result of the tensile strength test, in the case of sample 1,
There is no solder diffusion layer 45, and the tensile strength is 1.1 kg.
It was f, and the tensile strength was too small for practical use, and the judgment result was unacceptable.

In the case of Samples 2, 3, and 4, the tensile strengths were 7.5 kgf, 9.2 kgf, and 9.1 kgf, which were sufficient values for practical use.

From the above, the metal composition is Sn-Sb system and S
n / Sb is 90/10 by weight ratio, the solid phase line is 240 ° C. or higher, and the liquidus line is 268 ° C.
5 and subjected to the reflow treatment as in Samples 2, 3 and 4 described above and having a thickness of 5 to 40 μm in the base electrode 12a.
By generating the solder diffusion layer 45, the end electrode 12, the external metal terminal 3, and the end electrode 11 are excellent in tensile strength, have reflow resistance, and do not contain lead because they do not contain environmental pollution. It is possible to obtain a composite type multilayer capacitor having a joint structure between the external metal terminal 2 and the external metal terminal 2.

Similarly, the terminal portion 23 of the external metal terminal 2
And the conductor pattern 71, and the solder 8 used for soldering the terminal portion 33 of the external metal terminal 3 and the conductor pattern 72, respectively.
The above-mentioned Sn-Sb-based high temperature lead-free solder is used as 1. Also in this case, as in the case described above, a joining structure that has excellent tensile strength, has reflow resistance, and is unlikely to adversely affect the external circuit due to melting of the solder, etc. Obtainable.

In addition to the above-mentioned embodiment, the present invention is similarly applied to a composite type multilayer capacitor having a structure in which two or three ceramic capacitor elements 1 are connected and arranged between a pair of external metal terminals. it can.

Further, the composite multilayer capacitor of the present invention is
It is mainly suitable for use as a smoothing capacitor for a switching power supply.

Further, the present invention can be applied to an electrode joining structure such as a coil component or a resistance component.

[0043]

As described above, according to the present invention, the tensile strength between the end electrodes and the external metal terminals is excellent, the reflow resistance is excellent, and since lead is not contained, there is no fear of environmental pollution. An electronic component with an external metal terminal can be provided.

[Brief description of drawings]

FIG. 1 is a front view of a composite multilayer capacitor according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the composite multilayer capacitor of the present embodiment.

FIG. 3 is a partial cross-sectional view showing a connection state of the composite multilayer capacitor of the present embodiment with a circuit board.

FIG. 4 is a partial enlarged cross-sectional view showing a joint structure between an end electrode and an external metal terminal according to the present embodiment.

FIG. 5 is a diagram showing temperature conditions, reflow furnace time conditions, and tensile strength test results during reflow processing of samples 1 to 4 of the present embodiment.

FIG. 6 is an explanatory view schematically showing a solder diffusion layer generated between an end electrode and an external metal terminal in Samples 1 to 4 of the present embodiment.

FIG. 7 is an explanatory diagram showing a state of a tensile strength test of Samples 1 to 4 of the present embodiment.

[Explanation of symbols]

1 Ceramic capacitor element 2 External metal terminal 3 External metal terminal 4 Solder layer 5 Solder layer 11 Edge electrode 12 end electrodes 12a Base electrode 21 One end 22 Folding part 23 Terminal 31 one end 32 Folding part 33 terminal 42 Nickel plating layer 43 Tin plating layer 45 Solder diffusion layer 51 piano wire 70 circuit board 71 conductor pattern 72 conductor pattern 100 ceramic dielectric substrate 101 internal electrode 102 internal electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Takashi Kamiya, inventor             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. (72) Inventor Hiromi Kikuchi             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc.

Claims (3)

[Claims] 1. In an electronic component with an external metal terminal, an end electrode of an electronic component body and an external metal terminal are electrically joined via a solder layer, and an end electrode of the electronic component body and the external metal terminal are electrically connected. When joining and, the conductive component of the end electrode of the electronic component body diffuses into the solder layer and
An electronic component with an external metal terminal, wherein a diffusion layer having a thickness of μm or more is formed. 2. The solidus temperature of the solder layer is 230 ° C.
The above-mentioned Sn-Sb-based high-temperature solder, the end electrode of the electronic component body has Cu as a main component, and the metal component diffused into the solder layer is Cu. Electronic components with metal terminals. 3. An end electrode of the electronic component body has a Cu main component as a conductive component, and Ni is formed on an end surface of the end electrode.
Since the plating is formed and Cu that diffuses into the solder layer is N
The electronic component with an external metal terminal according to claim 1 or 2, wherein the electronic component is diffused through the i-plated layer and a diffusion layer is formed in a solder layer portion.