JP3350986B2 - Electronic components for surface mounting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component for surface mounting, such as a ceramic capacitor for surface mounting.

[0002]

2. Description of the Related Art In recent years, electronic components for surface mounting have been increasingly used as electronic components mounted on various printed circuit boards. Hereinafter, a description will be given of a manufacturing process of a surface mount ceramic capacitor which is one of the conventional surface mount electronic components.

FIG. 9 is a perspective view of a terminal mounted product of a conventional surface mount ceramic capacitor as a surface mount electronic component. 1
Is a main body of a ceramic capacitor for surface mounting, which is made of a dielectric ceramic substrate such as ceramic. Reference numeral 2 denotes an electrode made of silver or the like formed on both main surfaces of the front and back surfaces of the main body 1,
Is a lead terminal made of iron, nickel, copper or the like. The tip 4 of the lead terminal 3 is adhered to the electrode 2 by a conductive adhesive 5 such as high-temperature cream solder. The planar shape of the tip 4 is quadrangular, and the lead terminal 3 is bent from the edge of the tip 4 and rises.

[0004]

However, in the above-mentioned conventional structure, the adhesive force between the tip portion 4 and the electrode 2 is weak, so that transfer molding for forming an exterior material for molding and protecting the main body 1 is performed. The external force F such as the resin pressure at the time or the thermal stress at the time of soldering to the printed circuit board by the reflow processing of the finished product is concentrated near the fold curve 7 which is the fulcrum of the lead terminal 3 as shown in FIG. As shown in FIG. 10 (b), the lead terminal 3 floats up, and microcracks tend to occur between the lead terminal 3 and the electrode 2. As a result, the electrical characteristics of the electronic component for surface mounting are stabilized. There was a problem that it could not be obtained.

Accordingly, an object of the present invention is to provide an electronic component for surface mounting that can firmly adhere a lead terminal to an electrode and obtain stable electrical characteristics.

[0006]

For this purpose, in the electronic component for surface mounting according to the present invention, the lead terminal is partially cut and raised from the front end portion to be bent so that the front end portion is a fulcrum of the lead terminal. It extends forward and backward from the fold curve.

[0007]

According to the above construction, the fold curve, which is the fulcrum of the lead terminal, is located near the center of the tip, so that the peeling of the lead terminal from the electrode due to external force during transfer molding or the like can be firmly prevented.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a terminal mounted product of a surface mounting ceramic capacitor as a surface mounting electronic component according to an embodiment of the present invention. In FIG. 1, 1 is a main body made of a dielectric ceramic substrate, 2 is an electrode formed on the front and back surfaces, which are main surfaces of the main body 1, 3 is a lead terminal, 5 is an adhesive between the electrode 2 and the lead terminal 3. For example, a conductive adhesive such as a high-temperature cream solder applied to the tip 4 of the lead terminal 3.

FIG. 2 is a perspective view of a lead terminal of a surface-mounting ceramic capacitor as a surface-mounting electronic component according to an embodiment of the present invention and a tip end thereof, and FIG. 3 is an electronic component for surface mounting according to an embodiment of the present invention. FIG. 2 is an enlarged perspective view of a cut-and-raised portion of a lead terminal of a surface mounting ceramic capacitor as a component. FIG.
In FIG. 3, the lead terminal 3 is partially cut and raised from a flat tip portion 4 and is bent. A slit 6 is formed after the lead terminal 3 is cut and raised, and three tongue pieces 4 extending rearward from a fold curve 7 are formed at the tip end 4.
a has occurred. That is, the fold curve 7 which is the fulcrum of the lead terminal 3 is slightly closer to the center than the rear edge of the tip 4,
The tip 4 extends horizontally forward and backward from the folding line 7. Next, a method of manufacturing the surface mounting ceramic capacitor will be described.

The main body 1, which is a dielectric porcelain substrate, is composed of barium titanate as a main component, and several additives such as calcium carbonate and silica as subcomponents, mixed and dried by a usual ceramic method, and dried with polyvinyl alcohol or the like. Granulation with a binder,
It is formed by molding and firing, and has dimensions of an outer diameter of 6.0 mm and a thickness of 0.5 mm. An electrode 2 having an outer diameter of 5.0 mm and having silver as a main component and copper, nickel or the like as a sub-component is formed on the front and back surfaces of the main body 1. Further, as shown in FIG. 2, a conductive adhesive 5 is applied to the inner surface of the distal end portion 4 of the lead terminal 3 joined to the electrode 2. Next, as shown in FIG. 1, the main body 1 is inserted between the distal ends 4 of the left and right lead terminals 3, and the upper distal end 4 and the lower distal end 4 are brought into contact with the electrode 2 so that the lead terminals 3 are formed. The main body 1 is elastically clamped from above and below by the spring force of the above to make a product with lead terminals.

Next, the lead terminal-attached product is heated in a 400 ° C. high-temperature atmosphere for 3 minutes to perform a reflow treatment, and the conductive adhesive 5 is melted and cured, and then preheated to 170 ° C. for transfer molding. It is fixed in a mold, and has an outer diameter of 30 mm and a thickness of 1 using a transfer molding machine.
100k of 5mm tablet-shaped epoxy resin
Surface mounting by coating with an epoxy resin exterior material 9 having dimensions of 9 mm in the X direction, 8 mm in the Y direction, and 3 mm in the Z direction shown in FIG. 4 by press-fitting with a plunger at a pressure of g / cm ² for 120 seconds. To obtain a semi-finished product 10 of a ceramic capacitor for use. Next, after cutting the base end 3a of the lead terminal 3 of the semi-finished product 10 as shown in FIG. 5, it is bent along the side surface of the exterior material 9 to obtain a finished product of the surface-mounting ceramic capacitor 11.

After the thermal shock test, the pressure cooker test (hereinafter abbreviated as “PCT”) was performed on the surface mount ceramic capacitor 11 prepared as described above.

First, in a thermal shock test, n = 100 samples were heated at a temperature of + 125 ° C. for 30 minutes and then at −40 ° C.
Was moved for 2 seconds and cooled for 30 minutes. This is 200
After repeating this process twice, the device was allowed to stand at a temperature of 20 ° C. for 24 hours. Then, the capacitance and the dielectric loss tangent were measured, and then PCT was performed. 121 ° C, 2atm, 100% RH atmosphere 10
After leaving for 0 hour, the capacitance and the dielectric loss tangent were measured. The results are shown in (Table 1) and (Table 2).

[0015]

[Table 1]

[0016]

[Table 2]

As shown in (Table 1), in the thermal shock test, the rate of change in capacitance was maximum with respect to the initial value before the test, and the product of the present invention was-
0.24%, -1.25% for the conventional product, and + 0.11% for the change in dielectric loss tangent of the present invention at the maximum, and +1.43 for the conventional product
%Met. The average values are as shown in (Table 1). As shown in (Table 2), in the PCT, the rate of change in capacitance is the largest at -0.54% for the product of the present invention and-
8.38%, the change of dielectric loss tangent of the present invention is +
0.44% and + 8.72% for the conventional product. The average values are as shown in (Table 2). As can be seen from the above, it can be seen that the product of the present invention has a good bonding property between the lead terminal 3 and the electrode 2, and has an effect that it is difficult to increase the contact resistance due to thermal shock and penetration of moisture.

Next, the reason will be described with reference to FIGS. 6 (a) to 6 (c). As described above, the fold curve 7 of the lead terminal 3, that is, the joining line with the tip 4 is slightly near the center of the tip 4, and the tip 4 extends forward from the fold curve 7, and the tongue extends backward. The piece 4a extends. Therefore, even if the above-described external force F is applied to the folding curve 7 which is the fulcrum of the lead terminal 3, the external force F can be sufficiently counteracted, and the tip 4 is not easily peeled off from the electrode 2.

The cut-and-raised structure of the lead terminal 3 is not limited to the embodiment described above, and may be cut and raised as shown in FIGS. 7 and 8.
The tongue piece 4a extends rearward of the fold curve 7 so as to be closer to the center of the distal end portion 4 so as to oppose the external force F acting on the fulcrum of the lead terminal 3.

[0020]

As described above, according to the present invention, the bent curve of the lead terminal serves as the fulcrum of the lead terminal, but this fulcrum is located near the center of the tip end portion bonded to the electrode of the main body. The peeling of the lead terminals from the electrodes due to external force such as resin pressure or thermal shock during transfer molding can be firmly prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view of a terminal mounted product of a surface mount ceramic capacitor as a surface mount electronic component according to an embodiment of the present invention.

FIG. 2 is a perspective view of lead terminals of a ceramic capacitor for surface mounting as an electronic component for surface mounting according to an embodiment of the present invention, and a tip end thereof.

FIG. 3 is an enlarged perspective view of a cut-and-raised portion of a lead terminal of a surface-mount ceramic capacitor as a surface-mount electronic component according to an embodiment of the present invention.

FIG. 4 is a perspective view of a semi-finished product of a ceramic capacitor for surface mounting as an electronic component for surface mounting according to one embodiment of the present invention.

FIG. 5 is a perspective view of a surface mounting ceramic capacitor as a surface mounting electronic component according to an embodiment of the present invention.

FIG. 6A is a view showing a bonding state of lead terminals of a surface mounting ceramic capacitor as a surface mounting electronic component according to an embodiment of the present invention; FIG. FIG. 3C is a diagram showing the bonding state of lead terminals of a surface-mounting ceramic capacitor as an electronic component. FIG. 3C is a diagram showing the bonding state of lead terminals of a surface-mounting ceramic capacitor as a surface-mounting electronic component according to one embodiment of the present invention.

FIG. 7 is a perspective view of a lead terminal of a surface mount ceramic capacitor as a surface mount electronic component according to another embodiment of the present invention.

FIG. 8 is a perspective view of a lead terminal of a ceramic capacitor for surface mounting as an electronic component for surface mounting according to another embodiment of the present invention.

FIG. 9 is a perspective view of a terminal-attached product of a conventional ceramic capacitor for surface mounting as an electronic component for surface mounting.

FIG. 10 (a) is a view showing a bonding state of lead terminals of a conventional surface mounting ceramic capacitor as a surface mounting electronic component. FIG. 10 (b) is a diagram showing a bonding state of a surface mounting ceramic capacitor as a conventional surface mounting electronic component. Diagram showing bonding state of lead terminals

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body part 2 Electrode 3 Lead terminal 4 Tip part 4a Tongue piece 5 Conductive adhesive 9 Exterior material 11 Porcelain capacitor for surface mounting

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ohno 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-1-259517 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01G 4/00-4/40

Claims (2)

(57) [Claims] An electronic component for surface mounting in which a leading end of a lead terminal is adhered to a main surface of a main body portion with a conductive adhesive, wherein the lead terminal is partially cut and raised from the leading end to form a bend. The electronic component for surface mounting, wherein the tip portion extends forward and backward from a fold curve which is a fulcrum of the lead terminal. 2. The electronic device according to claim 1, wherein the main body is a dielectric ceramic substrate, and the electronic component for surface mounting is a ceramic capacitor for surface mounting.
2. The electronic component for surface mounting according to claim 1, wherein the front ends of the lead terminals are bonded to the front and back surfaces of the dielectric ceramic substrate.