JPH0595069U - Circuit board - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the circuit board bends, the stress exerted on the components mounted thereon is reduced and the destruction of the components is prevented. [Structure] The circuit board 11 includes a flexible circuit board 12 on which a component 14 is mounted, and a backing plate 13 having a relatively high rigidity for backing the flexible circuit board 12.
It has a layered structure. A cavity 16 is formed in the backing plate 13 at a portion where the component 14 is to be mounted. [Effect] Even if the entire circuit board is bent, the flexible circuit board can be independently deformed at the position of the cavity, so that the stress can be absorbed here and the stress can be prevented from being transmitted to the components.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circuit board, and more particularly, to a circuit board improved so as to prevent the components mounted thereon from being broken even if the board is bent.

[0002]

[Prior Art]

 FIG. 2A shows a conventional structure in which the component 2 is mounted on the circuit board 1. When mounting the component 2 as described above, the circuit board 1 and the component 2 are connected by the solder 3. The application of the solder 3 is performed by, for example, a reflow method. That is, after solder paste is applied on the electrode pattern of the circuit board 1 and the component 2 is placed thereon, soldering is achieved by the reflow method.

[0003]

[Problems to be solved by the device]

 It is assumed that the mounting structure as described above is applied to a card type electronic device such as an IC memory card. It is desirable that such a card-type electronic device be made thinner. For this reason, the card-type electronic device is liable to be bent as a whole, and the circuit board provided therein has only a thickness of, for example, about 0.1 to 0.5 mm.

In such a situation, when the card-type electronic device is flexed as a whole by an unexpected force from the outside, the circuit board 1 provided therein is also similarly provided as shown in FIG. 2B. Bend. As a result, the stress is applied to the component 2 via the solder 3, and the component 2 may be broken.

In particular, in the case of a card type electronic device, in order to reduce the thickness, the exterior of the component 2 is often simplified or the exterior is omitted, and the element is often exposed. For example, when the component 2 is a chip type surface acoustic wave filter, the glass plate is exposed. Because of this, the component 2 is vulnerable to stress and is easily destroyed.

In addition, when the card type electronic device is portable, it is always exposed to the risk of drop impact as well as static bending, and even in this case, there is a risk that the parts will be destroyed. In minutes.

[0007] Therefore, an object of the present invention is to provide a circuit board that can reduce the possibility of component destruction due to the stress as described above.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned technical problems, the circuit board according to the present invention has a two-layer structure of a flexible circuit board on which components are mounted and a backing board having a relatively high rigidity for lining the flexible circuit board. It is characterized in that a cavity is formed in the backing plate in a portion where components are to be mounted.

[0009]

[Action]

 Even if the circuit board according to the present invention is flexed as a whole, a cavity is formed in the backing plate in the portion where the components of the flexible circuit board are to be mounted. it can.

[0010]

[Effect of the device]

 Therefore, when mounting the components on the circuit board according to the present invention, if the position is selected to correspond to the cavity of the backing plate, even if the entire circuit board is deflected, the stress due to the deflection will cause the stress in the cavity position. Since it is absorbed by the part of the flexible circuit board in, it is possible to reduce the possibility that stress is transmitted to the component and the component is destroyed.

Therefore, the circuit board according to the present invention can be advantageously applied to card-type electronic devices that are required to be thin.

[0012]

【Example】

 FIG. 1 is a sectional view of a circuit board 11 according to an embodiment of the present invention. The circuit board 11 has a two-layer structure including a flexible circuit board 12 and a backing plate 13 that backs the flexible circuit board 12 and has a relatively high rigidity. The flexible circuit board 12 is formed by forming a desired circuit pattern on a base material made of a material such as polyimide or polyphenylene sulfide. The backing plate 13 is made of any material such as metal, ceramics, plastic, etc., but as an example, it is preferably made of a phenol resin laminated plate. The flexible circuit board 12 and the backing plate 13 are integrated by, for example, bonding. The circuit board 11 thus obtained can have a thickness equal to or less than the thickness of a conventional glass epoxy substrate, for example, 0.5 mm or less.

The component 14 is mounted on the flexible circuit board 12 using solder 15. The method of applying the solder 15 is similar to the conventional case. In this way, the cavity 16 is formed in the backing plate 13 in the portion where the component 14 is mounted (including the component 14 and the electrode portion connecting the component 14). The cavity 16 is formed by punching or drilling with respect to the backing plate 13 before being bonded to the flexible circuit board 12, and its planar shape is arbitrarily determined in consideration of the shapes of the component 14 and the connection electrode. You can choose.

As shown in FIG. 1B, in such a circuit board 11, when the flexible circuit board 12 in the position of the cavity 16 has a flexure, the flexure of the circuit board 11 as a whole is In addition, it can be easily deformed, and the stress due to this bending can be advantageously absorbed in this portion of the flexible circuit board 12. Therefore, the degree to which stress is transmitted to the component 14 can be reduced, and the possibility that the component 14 will be destroyed is reduced. Even when the circuit board 11 is bent in the direction opposite to the state shown in FIG. 1B, the flexible circuit board 12 is only pulled while keeping the flat state, so The stress due to the flexure is not applied.

The backing plate 13 functions so as to give rigidity to the circuit board 11 as a whole. Therefore, the circuit board 11 can be handled easily, and the steps of mounting the component 14 and the step of soldering can be performed without problems.

Further, the above-described cavity 16 may be formed only in a portion where a component that is easily broken is mounted.

[Brief description of drawings]

1A and 1B are cross-sectional views showing a circuit board 11 according to an embodiment of the present invention, in which FIG. Shown respectively.

FIG. 2 is a front view showing a conventional circuit board 1, (a)
Shows a state where the circuit board 1 is not bent, and (b) shows a state where the circuit board 1 is bent.

[Explanation of symbols]

 11 circuit board 12 flexible circuit board 13 backing plate 14 parts 15 solder 16 cavity

Claims (1)

[Scope of utility model registration request] 1. A two-layer structure including a flexible circuit board on which a component is mounted and a backing plate having a relatively high rigidity for backing the flexible circuit board, and the backing plate at a portion where the component is to be mounted. A circuit board having a cavity formed therein.