JPS5848496A - Miniature electronic circuit part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to small electronic circuit components.

The purpose of this is to have a high degree of integration, excellent heat dissipation, dimensional stability, and mechanical strength of the conductor foil. It is an object of the present invention to provide a small leadless electronic circuit component having a structure that allows reliable connection.

Small electronic circuit components have traditionally been called hybrid integrated circuit components, and various types are used depending on the purpose and application. It has also contributed greatly to the development of technology, and the representative examples are shown in Figure 1. This small electronic circuit component is based on a synthetic resin substrate such as paper phenol or glass epoxy.
A chip resistor and a chip capacitor are mounted on a so-called small-sized wired circuit board on which wired circuit conductors 2 are formed on one surface or on the front and back surfaces depending on the circuit scale.

Furthermore, mini-package transistors and integrated circuits (ICs)
) and other small circuit elements 3a, 3b are mounted at high density, and each circuit element 3a, 31 is assembled using soldering technology.
) and a wiring circuit conductor 2 are electrically interconnected with solder 4.

Small electronic circuit components with such a structure have a low degree of integration, and furthermore, their base substrates are made of synthetic resin substrates.

In heat treatment during manufacturing process. Disadvantages include warpage, twisting, and reduced dimensional stability due to expansion and contraction of the pace board, as well as poor heat dissipation properties of the circuit board when using circuit elements with high power.

On the other hand, in the conventional type of small electronic circuit components mentioned above, lead wires are often used for the external connection terminals. A commonly used method is to insert the wire into a round through hole drilled in the hole and then solder it. but.

In order to improve the economic efficiency of small electronic circuit components and to simplify the installation work on the mother printed wiring board, we have created a small printed circuit board in which lead wires are removed from electronic circuit components and one circuit element is mounted as an external connection terminal. Using a conductor layer (copper foil pattern) previously formed on top, this external connection terminal pattern is inserted into an elongated slit hole drilled in the mother printed wiring board, and then connected by soldering. A so-called leadless connection method may also be used.

However, if such an installation is to be carried out in a structure, the conductor layer that serves as the external connection terminal of the small electronic circuit component must be formed on both the front and back sides of the printed circuit board, otherwise it will not match the mother printed wiring board with the slit holes. The circuit design of the mother printed wiring board becomes very complicated if the connection is not successful and if the connection terminal is configured on only one side. Furthermore, in the leadless connection structure of small electronic circuit components shown in the conventional example, if the clearance between the slit hole of the mother printed wiring board and the connection terminal part of the small electronic circuit component is large, the connection of the mother printed wiring board by dipping with solder There was a drawback that the solder connection with the terminal part could not be made reliably, and if the clearance was made small, the workability of attaching small electronic circuit components to the mother printed wiring board became extremely poor.

According to the small electronic circuit component according to the present invention, many of the drawbacks of the conventional example described above are solved.

It has many features, and its structure will be explained in detail below based on the illustrated embodiments.

First, FIG. 2 shows a sectional view of a small electronic circuit component according to the present invention. As shown in FIG. 2, the small electronic circuit component according to the present invention has flexibility, heat resistance,
For example, polyimide resin and polyamide-imide resin have excellent electrical insulation properties.

On one surface of a thin sheet-like insulating substrate 6 made of polyester resin, epoxy resin, or the like.

A wiring circuit conductor 6 made of copper foil is formed, and a sheet-like insulating material having the same type of flexibility as the base insulating substrate is formed on the entire surface so that a part of the wiring circuit conductor 2 is exposed. Glue film 7.

A metal substrate 8 is placed on the other surface (back surface) of the flexible wiring board at an opposing position so that a bent portion of a certain width remains in a part of the center of the flexible wiring board that has been coated with so-called overlay. For example, an aluminum plate or anodized aluminum plate can be bonded with a thermosetting adhesive 9 made of epoxy resin or phenolic resin.
Glue with.

Chip resistors, chip capacitors, and even mini-package transistors are mounted on the lined circuit board.
101L of small circuit elements such as IC.

1obf, and solder each circuit element 10&, 10b to the exposed wiring circuit conductor 6 of the flexible wiring board using solder reflow or solder dipping technology.
The structure is connected by . In the small electronic circuit component according to the present invention, the external connection terminals 6', 6'' are attached to opposite end surfaces of the flexible wiring board backed by the metal substrate 8, with the bending portion of the flexible wiring board as the center. It is formed of conductive foil on the same surface as the wiring circuit conductor 6, and has a so-called leadless type structure.Furthermore, external connection terminals other than the external connection terminals 6'6'' of this small electronic circuit component are allowed. Needless to say, we aim to improve the reliability of the system.

Such a small electronic circuit component having a leadless external connection terminal according to the present invention can exhibit many features when attached to a mother printed wiring board.

That is, when attaching this small electronic circuit component to a printed wiring board, as shown in FIG. The external connection terminals 6 are bent so that the metal substrates 8 glued on the back face each other and are in contact with each other.
', 6'' are directly inserted into the elongated slit holes 13 made in the mother printed wiring board 12, and the mother printed wiring board is immersed in a melted Kenta tank to form the external connection terminals 5/, e# of small electronic circuit components. and mother printed wiring board 12
゜The connection terminal is connected to the 76 conductor, foil, 4□ is shown below, and 6 is connected. Because the insulating sheet 7 is coated with the insulating sheet 7), its spring properties are extremely strong, so even if the clearance when inserted into the slit hole 13 of the mother printed wiring board 12 is large, the There is almost no gap between the slit hole and the connecting terminal portion afterward, and the soldering between the connecting terminals can be reliably achieved. Furthermore, since the flexible insulating sheet 7 is adhered to the copper foil pattern of the bent portion of the flexible wiring board, the mechanical strength of the copper foil pattern of the bent portion is firmly maintained, and one circuit is This has the advantage of significantly improving reliability.

Furthermore, when the small electronic circuit component according to the present invention is attached to the mother printed wiring board 12, circuits are formed on both the front and back sides of the metal substrate.

Since the structure is such that the circuit elements are mounted on top of the
The heat dissipation properties for heat generated from high-power circuit elements are extremely good, and the use of a metal substrate allows for dimensions as an electronic circuit component.Consistency 9. Mechanical strength and other properties are comparable to conventional ones. is significantly improved compared to .

According to another embodiment of the small electronic circuit component according to the present invention, as shown in FIG. By using such a structure, not only the economic effect but also the reliability of the solder joint and the reliability of the mechanical strength of the copper foil pattern at the bent part are maintained. Since the thickness of the flexible wiring board backed by the metal substrate 8 can be reduced, the heat dissipation of one circuit can be improved.Furthermore, the land for holding the wiring circuit conductor on which the circuit elements are mounted can be formed with solder resist. . This improves pattern accuracy and enables high-density electronic circuit components.

As is clear from the above description, the small electronic circuit component according to the present invention has a high degree of integration, excellent heat dissipation, one-dimensional stability, and mechanical strength of the conductor foil, and is suitable for mother printed wiring boards. It has many excellent features regarding installation, and its industrial value is great.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining a conventional example of a small electronic circuit component, FIG. 2 is a cross-sectional view for explaining an embodiment of a small electronic circuit component according to the present invention, and FIG. 3 is a cross-sectional view for explaining an example of a small electronic circuit component according to the present invention. FIG. 4 is a sectional view for explaining the state of attachment of the small electronic circuit component to the mother printed wiring board, and FIG. 4 is a sectional view for explaining another embodiment of the small electronic circuit component according to the present invention. 6...Flexible insulating substrate, 6...Wiring circuit conductor, 6', 6"...External connection terminal conductor, 7.7'... Flexible insulation sheet, 8...
... Metal substrate, 9. Mountain... Adhesive, 10&, 10b.
...Small circuit element, 11゜16...Solder, 12...Mother printed wiring board, 13...
...Slit hole, 14...Mother printed wiring board connection terminal conductor layer. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 3 Figure 4

Claims (1)

[Claims] (1) A wiring circuit conductor is formed on one main surface of a flexible insulating substrate, and a flexible insulating sheet is bonded to the surface so that a part of the wiring circuit conductor is exposed. A flexible wiring board is constructed by bonding a metal substrate to the other side of the flexible wiring board, leaving a bent part in a part, and placing the flexible wiring board on the flexible wiring board lined with the metal substrate. A plurality of small circuit elements are mounted and electrically connected, and a conductor layer serving as an external connection terminal is formed along both end faces facing the bent portion of the flexible wiring board. Small electronic circuit parts. (2. A small electronic circuit component according to claim (1), characterized in that a flexible insulating sheet is adhered only to the periphery of the bent portion of the flexible wiring board.