JPH08148596A - Electronic part - Google Patents

Abstract

PURPOSE: To provide a structure which can improve the moisture resistance of an electronic part with a resin encapsulation. CONSTITUTION: In an electronic part, metallic terminals 11, 12 are connected electrically with an electronic part element, and the residual sections other than respective terminal lead-out sections 11a, 12a of the metallic terminals 11, 12 are covered with an encapsulation resin, and further, each of the metallic terminals 11, 12 is so formed that the surface of the metallic material made of iron is plated with nickel and silver layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component provided with a resin exterior, and more particularly to an electronic component having an improved structure of a terminal that is drawn out from the exterior resin.

[0002]

2. Description of the Related Art In various electronic components including surface acoustic wave devices, a resin exterior is often provided around the electronic component elements in order to improve the environmental characteristics of the electronic component elements.
As such a resin exterior packaging method, there are a method of constructing the exterior resin with a resin dip and a method of constructing the exterior resin with a mold resin. With reference to FIG. 1, a method of forming the resin exterior by resin dip will be described.
First, the metal terminals 1 and 2 are prepared. In the example shown in FIG.
One metal terminal 2 has an element mounting portion 2a having a relatively large area. That is, in the metal terminal 2, the terminal lead-out portion 2b extends from the rectangular plate-shaped element mounting portion 2a. A surface acoustic wave element 3 as an electronic component element is fixed on the element mounting portion 2a. The surface acoustic wave element 3 has comb-teeth electrodes 5 and 6 which are inserted into each other on a rectangular plate-shaped piezoelectric substrate 4. The piezoelectric substrate 4 is polarized in the direction of arrow P. That is, the polarization direction P is parallel to the direction in which the electrode fingers of the comb electrodes 5 and 6 extend.

The surface wave element 3 is excited by applying an alternating voltage from the comb-teeth electrodes 5 and 6, and the excited surface wave is reflected by both end faces of the piezoelectric substrate 4 and is an end face using BGS wave. It is a reflection type surface wave resonator.

One of the comb-teeth electrodes 5 is electrically connected to the metal terminal 1 by a bonding wire 7 made of a metal wire such as Au wire. The other comb-teeth electrode 6 is
Similarly, it is electrically connected to the metal terminal 2 by a bonding wire 8 made of Au wire or the like.

When the exterior resin is made of a resin dip, the above structure is prepared before forming the exterior resin, and then silicon rubber is applied around the surface wave element 3. The silicon rubber 3 is used to prevent the characteristics of the surface acoustic wave element 3 from changing due to the tightening stress due to the exterior resin formed later.

After applying silicon rubber around the surface wave element 3, the above structure is dipped in a molten resin and then cured to form an exterior resin 9 as shown by a chain line in FIG. As a material for forming the exterior resin 9, an epoxy resin having excellent airtightness and mechanical strength after curing is used.

In the method of forming the exterior resin from the mold resin, the metal terminals 1 and 2 are prepared as described above,
The surface acoustic wave element 3 is joined, the bonding wires 7 and 8 are connected, silicon rubber is applied, and then the obtained structure is placed in a molding die and molded. FIG. 2 shows an electronic component whose exterior is made of such a mold resin. The shape of the surface of the mold resin 10 depends on the shape of the prepared mold. Therefore, like the rectangular parallelepiped mold resin 10 shown in FIG. 2, the resin exterior can be accurately made into a rectangular parallelepiped shape, and the dimensional variation of the exterior resin is small.

The metal terminals 1 and 2 shown in FIG.
Although shown separately, it is usually connected to a metal hoop (not shown) until the step of forming the exterior resin, and is cut from the metal hoop after the exterior resin is formed by a resin dip or resin mold. Further, as the metal terminals 1 and 2, as shown in the sectional view of FIG. 3, Cu and Ag are usually sequentially plated on the surface of an iron or stainless steel-based metal material 1a which is inexpensive and excellent in mechanical strength. Then Cu
What formed layer 1b and Ag layer 1c is used. Alternatively, after performing Cu plating and Ag plating,
Further, it has been attempted to enhance the solderability of the metal terminals 1 and 2 by plating the surface with solder.

[0009]

However, an electronic component in which an exterior resin is formed by the above-mentioned resin dip,
The electronic component in which the exterior resin 10 is formed by resin molding has a drawback that the moisture resistance is not sufficient. That is, when used under conditions of high humidity, water may penetrate into the interior from the boundary between the metal terminals 1 and 2 and the exterior resins 9 and 10, and the electrical characteristics may deteriorate or fluctuate. It was

It is an object of the present invention to provide an electronic component having a resin exterior and having a structure excellent in moisture resistance.

[0011]

Means and Actions for Solving the Problems The inventors of the present application have made extensive studies to improve the moisture resistance characteristics of the electronic parts shown in FIGS. As a result, the exterior resin 9, 10
In the heat treatment process such as baking to harden the
In the metal terminals 1 and 2, the plated Cu is Ag
It was found that the Cu layer 1b may be diffused into the layer 1c and the Cu layer 1b may be corroded. Further, it has been found that a gap is formed at the boundary between the corroded surface of the Cu layer 1b and the Ag layer 1c, and water may enter the exterior resins 9 and 10 through the gap.

Therefore, the inventors of the present invention have adopted the above Cu layer 1b.
As a result of diligent examination to solve the problems caused by the corrosion of
As a metal terminal, the surface of the metal material is plated with Ni,
It has been found that the moisture resistance can be effectively enhanced by plating Ag on the plating layer, and the present invention has been completed.

That is, according to the present invention, the electronic component element, the plurality of metal terminals electrically connected to the electronic component element, and the outer side of the electronic component element and the metal terminal except for the tip side portion of the metal terminal are left. And an exterior resin formed so as to cover the metal terminal, wherein the metal terminal has a metal material, a nickel layer plated on the surface of the metal material, and a silver layer plated on the nickel layer. It is an electronic component.

In the present invention, as described above, the surface of the metal material is plated with nickel, and then the nickel layer is plated with silver. The nickel layer is difficult to diffuse into the silver layer at the processing temperature for curing the epoxy resin or the like used as the exterior resin. Moreover, unlike Cu, corrosion is unlikely to occur in the heat treatment step.

That is, according to the present invention, by forming the plating layer on the surface of the metal terminal with the Ni layer and the silver layer, corrosion and the like at the boundary portion of the plating layer of the metal terminal can be prevented, whereby the moisture resistance of the electronic component can be prevented. It is characterized by having enhanced sex.

The shape and the like of the metal terminal are not particularly limited, and the portion drawn from the exterior resin may be bent and extended at a certain angle in the middle in a certain direction. . Also, the metal terminal that is pulled out is bent along the outer surface of the exterior resin,
A chip-type electronic component may be configured thereby.

The metal material forming the metal terminal is not particularly limited, but iron or stainless steel, which is inexpensive and has excellent mechanical strength, is preferably used.

In the electronic component of the present invention, nickel is first plated on the surface of the metal material. The plating of the nickel layer can be performed by any method such as electrolytic plating or electroless plating. Although silver is plated on the nickel layer, the silver layer may be plated by an appropriate method such as electrolytic plating and electroless plating.

Further, Sn or Pb is provided directly or indirectly on the outside of the silver layer in order to enhance solderability.
The -Sn alloy layer may be formed by plating. Further, the exterior resin formed in the present invention may be composed of the above-mentioned molding resin, or is composed of a resin dip type exterior resin formed by immersing the electronic component element in a molten resin and then curing the same. May be. As will be apparent from the examples described below, since the mold type exterior resin is superior in moisture resistance to the resin dip type exterior resin, the exterior resin is preferably composed of the mold resin.

Further, the present invention is characterized in that the structure of the metal terminal is improved in order to improve the moisture resistance in the electronic component from which the metal terminal is drawn out as described above. It is not particularly limited. That is, in addition to the surface acoustic wave resonator described in the embodiments described later, various surface acoustic wave devices or various electronic component elements such as capacitors and piezoelectric elements can be used.

Further, in the case of having a vibrating portion such as a surface wave resonator, as will be apparent from the examples described later, in order to prevent characteristic fluctuations due to the tightening stress of the exterior resin around the electronic component element, A material having excellent flexibility may be applied to the periphery of the electronic component element in order to relieve external tightening stress such as silicon rubber. Alternatively, a wax for forming a space around the electronic component element is applied to the outside of the electronic component element, and the wax is scattered by the heat treatment when the exterior resin is cured, so that the space around the electronic component element is formed in the exterior resin. May be formed.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be clarified by describing embodiments with reference to the drawings.

First Embodiment FIG. 4 is a perspective view for explaining a process of manufacturing an electronic component according to the first embodiment of the present invention. First, the metal terminal 1
Prepare 1 and 12. The metal terminal 11 has a plurality of concave portions 13a to 13d and a convex portion 13e in a portion covered with an exterior resin in a later step. Similarly, also in the metal terminal 12, a plurality of concave portions 14a to 14c and convex portions 14d are formed. These recesses 13a to 13d, 14a to 14c
And the convex portions 13e and 14d are the outer resin and the metal terminal 11,
12 to increase the contact area with the metal terminal 1
It is provided to increase the adhesion strength between the outer resin and the outer resin.

The metal terminals 11 and 12 have terminal lead-out portions 11a, which are drawn out from the portion covered with the exterior resin.
12a. Further, the metal terminal 12 is provided with an element mounting portion 12b on which the electronic component element 15 is mounted. The electronic component element 15 is attached to the element mounting portion 12b of the metal terminal 12 using an insulating adhesive.

Although not clearly shown in FIG. 4, the electronic component element 15 uses the surface acoustic wave resonator 3 shown in FIG. 1 in this embodiment. The electronic component element 15 is electrically connected to the metal terminal 11 by the bonding wire 16 and electrically connected to the metal terminal 12 by the bonding wire 17.

In this embodiment, the metal terminals 11 and 12 are
Is a metal material 1 made of iron, as shown in the cross-sectional view of FIG.
8 has a structure in which a nickel layer 19 formed by plating nickel on the surface of 8 is formed, and a silver layer 20 is formed by plating silver on the nickel layer 19.

Further, in FIG. 4, a silicon resin 21 is applied in advance around the electronic component element 15 in order not to disturb the vibration of the surface acoustic wave resonator. Next, the structure shown in FIG. 4 is placed in a molding die, and the exterior resin is molded around the remaining portions of the metal terminals 11 and 12 except the terminal lead portions 11a and 12a. In this way, the electronic component 21 shown in FIG. 5 is obtained. In the electronic component 21, a resin exterior is applied with a mold resin 22.

In this embodiment, the metal terminals 11 and 12 have a structure in which the nickel layer 19 and the silver layer 20 are formed by plating on the outer surface of the metal material 18 made of iron as described above. The metal terminals 11 and 12 are less likely to deteriorate in the heat treatment step for forming the metal. Therefore, the electronic component 21 having excellent moisture resistance can be obtained. This will be described based on a concrete experimental result.

A surface wave resonator having a designed resonance frequency of 40 MHz is used as the electronic component element 15, and the metal terminals 11 and 1 are used.
As No. 2, the surface of a metal material made of iron was plated with Ni to a thickness of 2 μm, and then Ag was plated to a thickness of 2 μm. In addition,
An epoxy resin was used as the exterior resin 22, and a heat treatment was applied at a temperature of 150 ° C. during molding.

A plurality of electronic components 2 obtained as described above
1 was placed in an environment of 60 ° C. and a relative humidity of 95%, the amount of change in resonance frequency after a lapse of a predetermined time was measured, and moisture resistance was evaluated. The results are shown in Fig. 7. In addition, in FIG.
The left coordinate indicates the amount of change in the resonance frequency fr, and the right coordinate indicates the resonance frequency change rate (Δfr / fr) × 100 (%).
Indicates. It should be noted that Δfr indicates the amount of change in the resonance frequency.

For comparison, an electronic component with lead terminals was obtained in the same manner as in the above example except that a copper layer was formed in place of the nickel layer, and this was designated as Comparative Example 1. A moisture resistance test was performed on Comparative Example 1 as in the example.

As is apparent from FIG. 7, in the above moisture resistance test, in the electronic component 21 of the embodiment in which the silver layer was plated on the nickel layer, the amount of change in the resonance frequency was small even after 6000 hours or more. Therefore, it can be seen that excellent moisture resistance characteristics can be exhibited. On the other hand, in the electronic component of Comparative Example 1, it can be seen that the change amount of the resonance frequency becomes very large with the passage of time.

Although the thickness of the nickel layer is set to 2 μm in the above embodiment, the same effect can be obtained even if the thickness is reduced to about 0.5 μm.

Second Embodiment In the second embodiment, the exterior resin is a resin dip type exterior resin. The other points are similar to those of the first embodiment. That is, as shown in FIG. 9, the metal terminals 11 and 12 and the electronic component element 15 are arranged in the chip-type exterior resin 32. The metal terminals 11 and 12 and the electronic component element 15 have the same structure as shown in FIG.
Therefore, the corresponding portions will be denoted by the corresponding reference numerals and omitted by using the description given with reference to FIG.

Also in the present embodiment, the silicon resin 21 is provided in order to alleviate the tightening stress from the exterior resin around the electronic component 15 which is the surface wave resonator and prevent the characteristic of the surface wave resonator from fluctuating. Has been applied.

In this embodiment, the same structure as shown in FIG. 4 is dipped in a molten epoxy resin for forming the exterior resin 32, and then pulled up and cured to form the exterior resin 32. There is.

Also in this embodiment, the metal terminals 11 and 12 are used.
Has a structure in which the surface of a metal material made of iron is plated with Ni and Ag in that order, so that the moisture resistance of the electronic component 31 of the second embodiment can be effectively improved.

Specific experimental results when the electronic component 31 of the second embodiment is used will be described. Resonance frequency is 40
A surface wave resonator utilizing a BGS wave of MHz was prepared, and as the metal terminals 11 and 12, the metal material surface was plated with Ni to a thickness of 2 μm and Ag to a thickness of 2 μm as in the first embodiment. The thing prepared was connected with the surface wave resonator by the bonding wire. Then, after applying a silicone resin around the electronic component element, a molten epoxy resin (24
C.) and then pulled up to apply a resin dip, and the attached molten resin was cured to form the exterior resin 32. The humidity resistance characteristics of the plurality of electronic components 31 of the second embodiment thus obtained were evaluated in the same manner as the humidity resistance test conducted in the first embodiment. The results are shown in Fig. 10.

For comparison, the second film is used except that a copper film is plated to the same thickness instead of the nickel film.
An electronic component of Comparative Example 2 obtained in the same manner as in Example 1 was obtained.
A moisture resistance test was performed on the electronic component of Comparative Example 2 as in the electronic component 31 of the second embodiment. The results are also shown in FIG.

As is apparent from FIG. 10, in the electronic component of Comparative Example 2, the resonance frequency fluctuates greatly with the passage of time, whereas in the electronic component 32 of the second embodiment,
Resonance frequency change rate is 0.2% even after 10,000 hours
You can see that it is as small as the following.

In the electronic component of the present invention, the metal terminal is drawn out from the resin exterior, but this metal terminal is drawn out in the form of an electronic part with leads as in the first and second embodiments. It does not necessarily have to be. That is, the electronic component of the present invention is not limited to an electronic component of a type that is inserted into a through hole provided in a printed board and mounted.
For example, as shown in FIG. 11, a plurality of metal terminals 34 to 3 drawn from an exterior resin 33 made of a molding resin.
The tip side portions 34a to 36a of 6 may be bent so that they can be mounted on a printed circuit board in the same manner as a chip type electronic component. Further, a metal terminal drawn out from the exterior resin may be formed along the outer surface of the exterior resin to be configured as a chip-type electronic component.

[0042]

As described above, according to the present invention, the metal terminal includes the metal material, the nickel layer formed on the surface of the metal material by plating, and the silver layer formed on the nickel layer by plating. Therefore, in the heat treatment step for forming the exterior resin, the metal terminal is less likely to deteriorate such as corrosion. Therefore, it is possible to reliably prevent the intrusion of moisture, humidity, or the like from the metal terminal into the inside of the electronic component covered with the exterior resin, and it is possible to effectively improve the moisture resistance of the electronic component.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a structure of a conventional electronic component to which a resin dip type exterior resin is applied.

FIG. 2 is a perspective view showing an electronic component that is provided with a conventional molding resin.

FIG. 3 is a cross-sectional view of a metal terminal used in a conventional electronic component.

FIG. 4 is a perspective view for explaining a metal terminal and an electronic component element used in the first embodiment.

FIG. 5 is a perspective view showing an electronic component of the first embodiment.

FIG. 6 is a cross-sectional view of the metal terminal used in the first embodiment.

FIG. 7 is a diagram showing the moisture resistance characteristics of the electronic component of the first example and the electronic component of Comparative example 1.

FIG. 8 is a perspective view showing an electronic component according to a second embodiment.

FIG. 9 is a partial cross-sectional perspective view for explaining the internal structure of the electronic component according to the second embodiment.

FIG. 10 is a diagram showing the moisture resistance characteristics of the electronic component of the second embodiment and the electronic component of Comparative Example 2.

FIG. 11 is a perspective view showing another example of the shape of the electronic component.

[Explanation of symbols]

 11, 12 ... Metal terminal 15 ... Surface wave resonator as an electronic component element 16, 17 ... Bonding wire 21 ... Electronic component 22 ... Exterior resin 18 ... Metal material 19 ... Nickel layer 20 ... Silver layer 32 ... Exterior resin 33 ... Mold resin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Asada 2-26-10 Tenjin Tenjin, Nagaokakyo, Kyoto Prefecture Murata Manufacturing Co., Ltd. (72) Inventor Junya Ago 2-26-10 Tenjin, Nagaokakyo, Kyoto Stock Company Murata Manufacturing

Claims (4)

[Claims] 1. An electronic component element, a plurality of metal terminals electrically connected to the electronic component element, and a tip end side portion of the metal terminal is left to cover the electronic component element and the outer side of the metal terminal. An exterior resin formed, wherein the metal terminal has a metal material, a nickel layer plated on the surface of the metal material, and a silver layer plated on the nickel layer. parts. 2. The electronic component according to claim 1, wherein the exterior resin is a mold resin. 3. The electronic component according to claim 1, wherein the exterior resin is a resin dip type exterior resin formed by immersing an electronic component element in a molten resin and then curing it. 4. The electronic component according to claim 1, wherein a Sn or Pb—Sn alloy layer is plated on the silver layer.