JPH0696902A - Electronic parts - Google Patents

Abstract

(57) [Abstract] [Purpose] With regard to the structure of a chip-shaped electronic component, the purpose is to eliminate a short circuit between pads (electrodes) when mounted on a circuit board, reliably, without impairing economic efficiency and productivity. To do. [Structure] A desired element pattern 3 is formed on the surface of an insulating base 12, and an electrode 5 connected to the pattern 3 extends to the back surface of the base 12 through the side surface of the base 12, and the electrode 5 on the back surface of the base extends. An electronic component in which the existing portion 5a is connected to the pad 7 of the circuit board 6 with solder or conductive resin 8, and a recess 13 for separating the extended portion 5a of the electrode 5 is formed on the back surface of the base 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electronic component mounted on a circuit board by using a heat-fluidic conductive material (solder, conductive resin, etc.), and particularly, when mounting, the conductive material for connection flows, The present invention relates to a configuration that prevents a short circuit between them.

In recent years, high-density mounting has progressed, and electronic components mounted on a circuit board, such as a chip resistor, have been miniaturized, and it has become difficult to mount without short-circuiting between electrodes.
Therefore, it is necessary to facilitate normal implementation.

[0003]

2. Description of the Related Art FIG. 2 is a side view showing a conventional chip resistor and its mounting state. In FIG. 2A, the chip resistor 1 has a film resistor 3 formed on the surface of a rectangular base 2 made of ceramic or the like. The electrode 5 is connected to the opposite end of the film resistor 3 covered with the protective film 4, and the extending portion 5 a of the electrode 5 extends to the back surface of the substrate 2 through the side surface of the substrate 2.

In FIG. 2 (B), the circuit board 6 on which the chip resistor 1 is mounted is formed with a pad 7 opposed to the electrode extension 5a, and the extension 5a and the pad 7 opposed to each other are made conductive. It is connected by the resin 8.

The conductive resin 8 is generally made of a thermoplastic resin mixed with conductive particles, and is softened and easily flows during the heating process for curing. The base 2 of the miniaturized chip resistor 1 has a length of 2 mm, a width of 1.25 mm, and a thickness of 2 mm.
Distance l of the electrode extension 5a on the back surface of the substrate 2 of 0.5 mm
Is about 1 mm.

On the other hand, the thickness t _-1 of the electrode extension portion 5a is 10 μm.
The thickness t ₋₂ of the pad 7 formed by printing is about 10 μm. Therefore, the gap D ₋₁ between the back surface of the mounted chip resistor 1 and the circuit board 6 is such that the thickness of the conductive resin 8 sandwiched between the electrode extending portion 5a and the pad 7 is α≈30 μm. Then, D ₋₁ = t ₋₁ + t ₋₂ + α≈50 μm.

[0007]

As described above, when the conventional chip resistor 1 is mounted, the conductive resin 8 which becomes fluid during the hardening process is caused by the capillary phenomenon during the hardening process. There is a problem in that it easily flows into the gap between the back surface of No. 1 and the circuit board 6 and short-circuits the opposing pad 7 which should be isolated.

As a method of preventing a short circuit between pads, a method of forming a pedestal layer on a circuit board and forming a conductor layer on the board including the pedestal layer is known (Japanese Patent Laid-Open No. 61-296).
794).

The thickness of such a pedestal layer is generally 50 μm for a chip capacitor having a backside electrode thickness of about 50 μm.
Since it may be about m, it can be formed by one or two printing steps.

However, the pedestal layer for a small chip resistor needs to have a thickness of about 100 μm. In such a base layer, the printing process (printing / firing) is repeated 4 to 5 times, which makes it difficult to form a printed resistance element on the substrate on which the base layer is formed, which impairs economic efficiency and productivity. Like

[0011]

The present invention, which aims at eliminating the above-mentioned short circuit between pads without impairing the economical efficiency and the productivity, shows an embodiment of the insulating substrate according to FIG.
The required element pattern 3 is formed on the surface of 12 and the pattern 3 is formed.
The electrode 5 connected to is extended to the back surface of the base 12 through the side surface of the base 12, and the electrode extending portion 5a on the back surface of the base 12 is connected to the pad 7 of the circuit board 6 by the conductive resin (or solder) 8. The electronic component 11 to be connected has an electrode extension 5a on the back surface of the base 12.
A recess 13 is formed to separate the two.

[0012]

According to the above means, by providing the recess on the back surface of the electronic component, the conductive resin is prevented from flowing out due to the capillary phenomenon, and the short circuit between the pads is eliminated.

A recess for preventing a capillary phenomenon, for example, a recess having a depth of about 100 μm formed in a base body made of ceramic, can be easily formed by providing a convex portion on the molding die of the base body or by one grinding step. It is possible to form a printed circuit board, and it is more economical and productive than the conventional method of forming a pedestal layer with a thickness of about 100 μm on a circuit board, and there is no risk of hindering the formation of printed resistance elements on the mounting board. .

[0014]

1 is a side view showing a chip resistor according to an embodiment of the present invention, its mounting method, and a mounted state.

In FIG. 1A, a chip resistor 11 forms a film resistor 3 on the surface of a rectangular base 12 made of ceramic or the like. The electrode 5 is connected to the opposite end of the film resistor 3 covered with the protective film 4, and the extending portion 5 a of the electrode 5 extends to the back surface of the base 12 through the side surface of the base 12.

A recess 13 is provided on the back surface of the base 12 to separate the electrode extension 5a. Thickness t is 0.5 mm due to grinding, etc.
The recess 13 formed in the base body 12 has a depth d of 100 μm, for example.
It is about 150 μm.

In FIG. 1B, a pad 7 opposed to the electrode extension 5a is formed on the circuit board 6 on which the chip resistor 11 is mounted, and a conductive resin 8 is printed on the pad 7. Then, so that the electrode extension portion 5a faces the pad 7,
When the chip resistor 11 is mounted on the circuit board 6 and the conductive resin 8 is cured (heated), the hardened conductive resin 8 causes the chip resistor 11 to move to the circuit board 6 as shown in FIG. 1 (C). Will be implemented in.

Therefore, the gap D ₋₂ between the bottom surface of the recess of the mounted chip resistor 11 and the circuit board 6 is the thickness t ₋₁ ≈10 μm of the electrode extension 5a, and the thickness of the pad 7 formed by printing. t _-2 ≈ 10
If the thickness of the conductive resin 8 sandwiched between the electrode extending portion 5a and the pad 7 is α≈100 μm, then D ₋₂ = t ₋₁ + t ₋₂ + α ≈150 μm.

Therefore, the conventional capillary phenomenon does not occur in the conductive resin 8 which becomes fluid by the heat treatment for hardening, and the conductive resin 8 can be prevented from almost flowing out from the pad 7. Becomes

[0020]

As described above, according to the present invention, by providing the recess on the back surface of the substrate of the electronic component, the conductive resin is prevented from flowing out due to the capillary phenomenon, and the short circuit between pads is eliminated. You can

Moreover, the recess of the electronic component in the present invention is easy to form, and the conventional circuit board on which the circuit element is printed and formed can be used (not obstructing the printed formation of the circuit element). By forming the pedestal layer on the circuit board by the conventional method, it is excellent in economy and productivity.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a chip resistor according to an embodiment of the present invention and its mounting.

FIG. 2 is a side view showing a conventional chip resistor and its mounting state.

[Explanation of symbols]

 3 is an element pattern formed on the surface of an insulating substrate 5 is an electrode connected to an element pattern 5a is an electrode extension 6 is a circuit board for mounting electronic parts 7 is a pad formed on the circuit board 8 is a conductive part for mounting electronic parts Resin (heat-flowable conductive material) 11 is an electronic component 12 is an insulating base of an electronic component 13 is a recess of an insulating base

Front page continuation (72) Inventor Kazuhisa Fujisawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited

Claims (1)

[Claims] 1. A desired element pattern (3) is formed on a surface of an insulating substrate (12), and an electrode (5) connected to the pattern (3) passes through a side surface of the substrate (12) to form the substrate (12). 12) extend to the back side,
An electronic component in which the extended portion (5a) of the back electrode (5) of the base body (12) is connected to the pad (7) of the circuit board (6) by solder or conductive resin (8). An electronic component characterized in that a recess (13) for separating the electrode extension (5a) is formed on the back surface of (12).