JPH03224286A - Flexible wiring board utilizing conductive layer - Google Patents

Abstract

PURPOSE:To form an electrically stable shield structure having a simple structure on the flexible wiring board of a camera on which a photometric element and photometric IC are connected with each other by holding a conductive layer formed on a pattern at prescribed electric potential. CONSTITUTION:A flexible wiring board 1 on which a photometric IC 3 is mounted is provided in such a way that the IC 3 is united with a photometric element mounting section 10 through an interconnecting section 8. The wiring pattern 6 connected with a photometric element 2 is connected to the IC 3 through the section 8 along with the wiring of a guard ring 9 constituted so as to surround the element 2. A conduction land 5 is provided on the board 1 and the wiring extended from the land 5 is connected with GND potential. Moreover, insulating layers 7 are formed on both surfaces of the board 1 except the parts where the land 5, contacts between the IC 3 and pattern 6, and element mounting section are formed or mounted. A surface conductive layer 4a and rear-surface conductive layer 4b become the same potential as the GND potential through the land 5 and layer 4a and a punched hole 11, respectively, and all of the parts where the conductive layers are applied become shields against electro-magnetic noise.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to flexible wiring boards used in cameras, especially those that handle minute currents that are susceptible to electromagnetic noise.
The present invention relates to a flexible wiring board for a camera that has a pattern connecting a photometric element and a photometric IC.

Conventional technology Conventionally, in wiring boards that are commonly used,
Various methods have been proposed as methods for preventing electromagnetic noise from being generated in wiring patterns on a substrate. For example, in Utility Model Application No. 62-192699, a surface protective layer is formed of wiring batters and the like that require shielding. Further, a shield portion is provided which is integrally formed with the flexible wiring board main body. The width, length, and other shapes of this shield part are determined in accordance with the shape of the flexible wiring board body that requires the shield. linked. At this time, a shield pattern is arranged on the shield part, and a surface protective layer similar to the above is provided. Since this shield pattern is connected to the ground wiring of the flexible wiring board main body through the connecting portion, the shield pattern has a ground potential. After this shield portion is folded at the connecting portion and superimposed on the flexible wiring board main body, only both ends of the shield portion are bonded to the flexible wiring board main body using an adhesive. Although this makes it possible to obtain a shielding effect without reducing the bending characteristics of the flexible wiring board main body, it is necessary to newly provide a shield portion that is integrated with the flexible wiring board main body.

Furthermore, Japanese Utility Model Application No. 60-76092 discloses a method of obtaining a shielding effect by forming a conductive layer on a patterned flexible wiring board body through an insulating layer. Here, a conductive layer is formed by closely adhering a conductive sheet or applying a conductive material to both surfaces of the flexible wiring board main body having a pattern, except for the connection part or the mounting part, thereby creating a shield structure. This makes it possible to obtain a shielding effect with a simple structure, but
The influence of the potential of the conductive layer is not taken into consideration.

In addition, as a conventional example that solved the above problem, an insulating layer is formed on a substrate with a pattern, except for a part with a ground potential, and a conductive layer is further formed on top of the insulating layer, and the conductive layer and the ground potential are A printed wiring board is known in which a conductive layer is brought to a ground potential by contacting a circuit with a conductive layer. In this wiring board, it is necessary to have a shielding effect by having a conductive layer at a ground potential, or to provide a pattern having a ground potential on each of the front and back if shielding is required on both the front and back.

On the other hand, in the field of cameras, in order to reduce the influence of electromagnetic noise on the photometric output from the photometric element, it is known to combine a photometric element and an amplifier into one package. This reduces the influence of electromagnetic noise, but on the other hand, it increases the size of the photometric element, which imposes design constraints and inevitably increases costs.

Problems to be Solved by the Invention Conventionally, photometric ICs have been
There were issues to consider regarding the shield structure for the patterns formed during the process. One of the issues is how to simply configure the shield structure. Wiring boards that handle minute currents that require a shield structure are often housed in a limited space within a structure, and their volume is required to be as small as possible.

Furthermore, in order to shield minute currents, it was necessary to provide as electrically stable a shielding effect as possible.

An object of the present invention is to obtain a structure of a wiring board that can stably prevent electromagnetic noise to a pattern formed between a photometric element and a photometric IC using the simplest possible method.

Means for Solving the Problems In the present invention, an insulating layer is provided for surface protection and insulation on a flexible wiring board on which a pattern that requires shielding between a photometric element and a photometric IC of a camera is arranged, and an insulating layer is provided on the flexible wiring board for surface protection and insulation. Form a conductive layer. At that time, a part of the wiring pattern is exposed by opening the insulating layer. The exposed portion has a structure in which the conductive layer and the wiring pattern are in contact with each other.

In order to reduce the influence of electromagnetic noise on the photometric output from the photometric element in the camera, the above configuration simply forms the conductive layer on the insulating layer, leaving the conductive layer and wiring pattern exposed. The connected parts are electrically connected. As a result, if the connected wiring pattern has a predetermined potential, the conductive layer also has the same potential as the wiring pattern and has a shielding effect.

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

FIG. 1 is a schematic plan view of a noise countermeasure structure of a double-sided flexible wiring board l of a camera that handles signals from a photometric element to a photometric IC, and FIG. 2 is a sectional view taken along line A-A. In the figure, there is a flexible wiring board 1 on which a photometric IC 3 is mounted, which is integrally formed with a photometric element mounting section 10 via a connecting section 8 .

The wiring pattern 6 connected to the photometric element 2 is connected to the photometric element 2.
It is connected to the photometric IC 3 through the continuous portion 8 together with the wiring of the guard ring 9 configured to surround the photometric IC 3. A conductive land 5 is provided on the flexible wiring board l,
The wiring extending from there is connected to the GND potential. In addition, the conductive land 5 of the flexible wiring board 1, the photometric IC
An insulating layer 7 is formed on both surfaces except for the contact points between the wiring pattern 3 and the wiring pattern 6 and the mounting portion of the photometric element 2. A conductive layer 4 shown by hatched areas in FIGS. 1 and 2 is formed in the portion where the insulating layer 7 is formed, excluding the mounting portion of the photometric IC 3. Furthermore, before applying the conductive layer, a punch hole 11 is punched in the substrate, and the conductive layer is applied to both the front and back surfaces from above. Thereby, the conductive layers on the front and back surfaces are connected.

Here, silver paste or copper paste is used as the conductive material for the conductive layer, but it is not limited to these as long as it has a shielding effect to prevent electromagnetic noise. In addition, although coating is used as the method for forming the conductive layer in this example, it is also possible to form the conductive layer by thinly vapor-depositing indium tin oxide (ITo) or NESA film, or by closely adhering the conductive film. can be formed.

In this embodiment, the surface conductive layer 4 of the formed conductive layers is
The back side conductive layer 4b has the same potential as GND through the conductive land 5 and the front side conductive layer 4a and the punch hole 11, so that the entire portion coated with the conductive layer has a shield structure against electromagnetic noise.

In this embodiment, a double-sided flexible wiring board is used, but the present invention is not limited to this, and a single-sided flexible wiring board can also be used.

Further, FIG. 3 shows another embodiment for obtaining a shield structure in a single-sided flexible wiring board. In FIG. 3, the front surface has a structure similar to that of the embodiment shown in FIG. 1, but there is no punch hole 11, and the back surface is only coated with a conductive layer and has no pattern. In addition, the continuous part 8
There is a conductive land 13 similar to the conductive land 5 which is wired from the conductive land 5, and a protrusion 12 with a coverlay formed on the part other than the conductive land 13 is provided. This protruding portion 12 is turned from the front and bent toward the back side, so that the conductive land 13 and the back conductive layer are brought into contact with each other and electrically connected. Note that the protrusion 12 is fixed using conductive double-sided tape or the like. Figure 3a shows the protrusion 1
2 shows the unfolded state, and b shows the state in which the protrusion 12 is bent and brought into contact with the back conductive layer.

In such an embodiment, the front conductive layer is electrically connected to the ground through the conductive land 5, and the back conductive layer is electrically connected to the GND through the conductive land 13 provided on the protrusion 12. As a result, the entire portion coated with the conductive layer becomes a shield structure against electromagnetic noise.

In the embodiment shown in FIG. 3, the conductive land 13 may not be provided, but the protrusion 12 may also be coated with a conductive layer, and the protrusion 12 may be turned from the front and bent toward the back side to contact the back conductive layer. Here too, the protrusion 12 is fixed using conductive double-sided tape or the like. With this arrangement as well, the same effect as the embodiment shown in FIG. 3 can be obtained.

Further, FIG. 4 shows a first modification of a method for obtaining a shielding effect against electromagnetic noise by applying a conductive layer to the outside of a wiring pattern via an insulating layer in a flexible wiring board. In FIG. 4, the structure is very similar to the embodiment shown in FIG. 2, but the conductive land 5 is not provided. At this time, a conductor portion 12 of the body having a GND potential is brought into contact with a part of the surface conductive layer. As a result, the conductive layer has the same potential as GND, and has the same rolled effect as the embodiment shown in the second factor.

Figure 5 shows that in a flexible wiring board, by applying a conductive layer to the outside of the wiring pattern via an insulating layer,
This is a second variant of the method for obtaining a shielding effect against electromagnetic noise. A wiring pattern 6 is formed on the surface of the flexible wiring board l, and chip components 14 such as ICs are mounted thereon.

A coverlay 7 is formed thereon in a portion excluding the mounting portion of the chip component 14 and the connection portion between the wiring pattern and the chip component 14. Further, a conductive layer 4 is applied to the back surface of the flexible wiring board l. This flexible wiring board 1 is bent into a box shape with the surface coated with the conductive layer 4 facing outward. As a result, the shielding effect on the electric circuit surrounded by the conductive layer 4 is equivalent to that when the electric circuit is surrounded by a metal box. In addition, if this conductive layer 4 is brought into contact with a conductor portion of the body having a GND potential, a more stable shielding effect can be obtained.

In the embodiment shown above, the wiring pattern connected to the conductive layer at the conductive land 5 is not limited to the GND potential, but can also be a wiring pattern having a predetermined potential. Furthermore, it is useful not only for small signals from photometric elements but also for areas where noise countermeasures are required.

Effects of the Invention In a flexible wiring board for a camera that connects a photometric element and a photometric IC having the configuration shown in the present invention, a conductive layer formed on a pattern is held at a predetermined potential. As a result, it is possible to form a shield structure that is simpler and more electrically stable than the conventional example, and the photometric element can be used without being packaged with the amplifier, which requires ease of configuration and stability. It is ideal for shielding structures for minute currents.

[Brief explanation of drawings]

Fig. 1 is a schematic plan view of a double-sided flexible wiring board for a camera using the shield structure of the present invention, Fig. 2 is a sectional view taken along line A-A of the embodiment shown in Fig. 1, and Fig. 3 has a conductive land. A schematic plan view of a single-sided flexible wiring board for a camera in which the protruding part is bent and brought into contact with the back conductive layer. Figure 4 is a plan view of a double-sided flexible wiring board in which a part of the front conductive layer is brought into contact with the conductor part of the body having a GND potential. FIG. 5 is a schematic plan view of a modified example in which a single-sided flexible wiring board is bent into a box shape and has a shield structure. 1, flexible wiring board 2, photometric IC 3, photometric element 4, conductive layer 6, wiring pattern 7, insulating layer

Claims (1)

[Claims] A flexible wiring board for a camera that connects a photometric element and a photometric IC includes a board, a wiring pattern formed on the surface of the board and having a predetermined potential part, and a wiring pattern on the wiring pattern excluding at least a part of the predetermined potential part. 1. A flexible wiring board comprising: an insulating layer formed on a substrate; and a conductive layer formed on the insulating layer and in contact with the predetermined potential portion.