JP2009200292A - Flexible printed wiring board, and forming method for projection structure of wiring board - Google Patents

Abstract

To provide a flexible printed wiring board capable of securely holding a convex structure by a simple convex structure forming method.
An FPC 10 is placed on a lower mold 21 with a bar-like spacer 16 extending in the width direction of a base film 11 and an adhesive sheet 17 sandwiched between the FPC 10 and a wiring 12 facing upward. The base film 11, the wiring 12, and the reinforcing plate 15 of the FPC 10 are deformed by pressing that lowers the upper die 22 at a high speed. A part of the base film 11, the wiring 12, and the reinforcing plate 15 is deformed by the spacer 16, and a convex portion 18 having a shape following the concave portion 22 a of the upper mold 22 is formed. And the spacer 16 is engage | inserted by the recessed part 19 formed in the back side of the convex part 18. As shown in FIG.
[Selection] Figure 1

Description

  The present invention relates to a flexible printed wiring board and a method for forming a convex structure of the wiring board.

  2. Description of the Related Art Conventionally, film-shaped wiring bodies, so-called flexible printed wiring boards, are often arranged particularly in small and light electrical devices such as mobile phones. Since the flexible printed wiring board is extremely convenient for electrical connection in a device having an opening / closing mechanism and a rotating mechanism such as a mobile phone, the frequency of use has increased in recent years.

The following methods are known as a method for connecting a flexible printed wiring board to a mother board or the like.
First, there is a method using a known ZIF connector. In this case, the electrical connection between the two is ensured by pressing the conductor layer of the flexible printed wiring board and the conductor layer in the mother board or the connector with a spring member provided in the connector.
On the other hand, in Patent Document 1 and the like, the closest conductive layers are conducted by interposing an anisotropic conductive film (ACF) between the conductive layer of the flexible printed wiring board and the conductive layer of the mother board. It has a structure.
In addition, as a well-known technique, an insulating film (NCF) such as epoxy is interposed between the conductor layer of the flexible printed wiring board and the conductor layer of the mother board, and the electrical connection between the two by the shrinkage force of NCF. Techniques for securing this are also known.

JP 2002-314216 A

By the way, when any of the above connection methods is used, reliable connection is ensured because the two conductor layers to be connected are in contact with each other in a concentrated region as much as possible.
Therefore, it is conceivable to form a protrusion on the conductor layer by etching or the like, or to form a convex structure on the flexible printed wiring board itself.

However, etching the conductor layer of the flexible printed wiring board requires considerable labor, such as forming a resist mask.
On the other hand, even if the flexible printed wiring board is simply pressed to form the convex portion, it is difficult to reliably hold the convex portion with the flexible flexible printed wiring board.

  The objective of this invention is providing the flexible printed wiring board which can hold | maintain the structure of a convex part reliably, employ | adopting a simple processing method.

  In the flexible printed wiring of the present invention, a convex portion formed by projecting the base film and the conductor layer to the conductor layer side is extended in the width direction of the base film, and a spacer is attached to the concave portion formed on the back side of the convex portion. is there. Only one place may be sufficient as a convex part, and it may be provided in multiple places.

Thus, even when various stresses are applied to the convex portion during connection or use of the flexible printed wiring board, the spacer attached to the concave portion is a structure of the convex portion of the base film and the conductor layer (hereinafter referred to as a convex structure). ) To prevent collapse. Therefore, the flexible printed wiring board which can hold | maintain a convex structure reliably is obtained.
Then, when the flexible printed wiring board is connected to the mother board or the like via various connectors such as ZIF connectors, ACF, NCF or the like, the convex portion of the conductor layer of the flexible printed wiring board and the conductor layer of the mother board or the like Since electrical connection is performed in a concentrated area, a highly reliable connection structure can be obtained.

  By sticking the reinforcing plate to the back surface of the base film, the convex structure can be more reliably held. In that case, convex portions and concave portions may be formed on the base film, the conductor layer, and the reinforcing plate, and the spacer may be fitted into the concave portions formed on the reinforcing plate, or the reinforcing plate may be placed on the back surface of the base film with the spacer interposed therebetween. The latter may have an advantage that the spacer can be held firmly.

  Moreover, when using a double-sided circuit type flexible printed wiring board, the convex part by which the spacer was attached to the back side can be formed in both surfaces.

  The method for forming a convex structure of a wiring board according to the present invention is a method in which a bar-shaped or cylindrical spacer extending in the width direction is disposed on the back surface side of a base film, and the base film and the conductor layer are deformed by press working with the spacer interposed therebetween. It is.

  By this method, the base film and the conductor layer are pressed to form a convex portion protruding by the spacer and a concave portion on the back side thereof, and the spacer is fitted into the concave portion. Therefore, a flexible printed wiring board having a convex structure whose shape is reliably held can be obtained by a simple processing method called press processing, and a highly reliable connection can be achieved while suppressing an increase in manufacturing cost.

When attaching a reinforcing plate to the base film, before placing the spacer, attach the reinforcing plate to the back of the base film, and sandwich the spacer to deform the base film, conductor layer and reinforcing plate by pressing There is a method in which a reinforcing plate is disposed on the back surface side of the base film with the spacer interposed therebetween, and the base film and the conductor layer are deformed by pressing with the reinforcing plate and the spacer interposed therebetween.
In any of the methods, a reinforcing plate is attached in addition to the spacer, thereby forming a convex structure that is less likely to collapse. However, the latter method holds the spacer more firmly.

  In addition, for a double-sided circuit type flexible printed wiring board, a convex structure in which a spacer is fitted on the back side can be formed on both sides by placing spacers on both sides and pressing.

  According to the flexible printed wiring board or the method for forming a convex structure of the wiring board of the present invention, it is possible to provide a flexible printed wiring board that can reliably hold the convex structure by a simple convex structure forming method.

(Embodiment 1)
-Method for forming convex structure-
1A to 1C are cross-sectional views illustrating a method for forming a convex structure according to Embodiment 1 of the present invention.
First, an FPC 10 (flexible printed wiring board) shown in FIG. The FPC 10 includes a base film 11, a wiring 12 (conductor layer) provided on the upper surface 11 a side of the base film 11, a cover lay 13 that exposes the tip of the wiring 12 and covers other portions, and the base film 11. And a reinforcing plate 15 made of an elastic material provided on the lower surface 11b side. That is, it has a single-sided circuit type structure.

As a material of the base film 11, a polyimide plate having a thickness of about 12.5 μm to 125 μm is used. Not only a polyimide board but a polyester board (low temperature use), a glass epoxy board (thin board), etc. can also be used.
The material of the wiring 12 is generally a copper alloy, but is not limited to this.

As the material of the reinforcing plate 15, generally, a paper phenol plate, a glass epoxy plate, a polyimide plate, a polyester plate, a metal plate, and the like are used. In the present invention, the elasticity when the base film 11 is bent is used. For the purpose of reinforcing the force, it is preferable to use a metal thin plate such as aluminum, copper, SUS or the like having a thickness of 30 μm to 100 μm. In that case, the reinforcing plate 15 is adhered to the base film 11 by a thermosetting adhesive such as an epoxy sheet or a pressure sensitive adhesive such as a double-sided pressure-sensitive adhesive sheet. Among them, it is preferable to use an adhesive sheet in terms of low cost and simple process.
Note that the reinforcing plate 15 is not necessarily provided.

  As a material of the cover lay 13, a film cover lay made of the same material as the base film 11, a cover coat ink formed by printing a liquid epoxy resin ink, or a resin such as epoxy, acrylic, polyimide, polyurethane, or the like is used. There is a photosensitive coverlay used, and any of them may be used.

Next, as shown in FIG. 1B, a lower die 21 having a flat upper surface and a press die having an upper die 22 having a recess 22a extending in the direction perpendicular to the paper surface on the lower surface is used. A state in which the wiring 12 faces the FPC 10 upward with a rod-like spacer 16 extending in the width direction (perpendicular to the paper surface) of the base film 11 and an adhesive sheet 17 such as an epoxy sheet on the mold 21 Place in.
The lower mold 21 may be formed with a pair of low protrusions for fixing the spacer 16.

  The material constituting the rod-shaped spacer 16 may be a conductor material or an insulating material such as various metals, ceramics, and hard plastic. Further, it may be a cylinder instead of a rod, and the cross-sectional shape may be any shape such as a circle, a rectangle, a triangle, a polygon, and an ellipse.

Next, as illustrated in FIG. 1C, the base film 11, the wiring 12, and the reinforcing plate 15 of the FPC 10 are deformed by press working that lowers the upper die 22 at a high speed. At this time, a part of the base film 11, the wiring 12, and the reinforcing plate 15 is deformed by the hard spacer 16, and the convex portion 18 having a shape following the concave portion 22 a of the upper mold 22 is formed. Then, the spacer 16 is fitted into the concave portion 19 formed on the back side of the convex portion 18.
Note that heat may be applied to the FPC 10 or the like during pressing.

  The diameter of the spacer 16 is about 0.1 mm to 0.2 mm, the outermost radius of curvature of the convex portion 18 is about 0.3 mm to 0.6 mm, and the width (front-rear direction) of the convex portion 18 is It is about 0.8 mm to 1.5 mm.

  According to the FPC 10 and the method for forming the convex structure in the present embodiment, the convex portion 19 from which the wiring 12 protrudes can be formed easily and quickly by a simple processing method called press processing. At that time, since the spacer 16 is fitted in the concave portion 19 on the back side of the convex portion 18, even when various stresses are applied to the convex portion 18 during connection or use of the FPC 10, the spacer 16 fitted in the concave portion 19. However, it plays the role which prevents that the structure (convex structure) of the convex part 18 of the base film 11 and the wiring 12 collapse | crumbles. Therefore, FPC10 which can hold | maintain a convex structure reliably is obtained.

  Note that the adhesive sheet 17 is not necessarily provided. This is because depending on the material of the reinforcing plate 15, the reinforcing plate 15 can hold the spacer 16 by pressing.

-Connection method 1
FIG. 2 is a perspective view showing an example in which the FPC 10 according to the present embodiment shown in FIG. 1C is connected to an existing connector.
As shown in the figure, a general-purpose connector 40 such as a ZIF connector is mounted on a mother board 30 such as a PWB (rigid printed wiring board). Then, by inserting the distal end portion of the FPC 10 having the convex portion 18 provided on the wiring 12, the concave portion 19 on the back side thereof, and the spacer 16 fitted in the concave portion 19 into the connector 40 and closing the lid, the FPC 10 The wiring 12 and the corresponding connecting member of the connector 40 are pressed by the spring mechanism and electrically connected in a concentrated area. Further, the FPC 10 can be easily removed by opening the cover of the connector 40. That is, the front end portion of the FPC 10 on which the convex portion 18 is formed has a structure that can be inserted into and removed from the connector 40.

-Connection method 2-
FIG. 3 is a cross-sectional view showing an example in which the FPC 10 according to the present embodiment shown in FIG. 1C is directly connected to the mother board.
As shown in the figure, the FPC 10 is placed on the mother board 30 on which the wiring 32 is formed on the board 31 with the projections 18 facing downward. An ACF 35 is interposed between the FPC 10 and the wiring board 30 in a state where the wiring 32 of the wiring board 30 and the convex portion 18 of the wiring 12 of the FPC 10 are in contact with each other.
Thereby, the wiring 12 of the FPC 10 and the wiring 32 of the wiring board 30 are reliably electrically connected by the ACF 35 in the concentrated region. Instead of the ACF 35, NCF may be used.

(Embodiment 2)
4A to 4C are cross-sectional views showing a method for forming a convex structure according to Embodiment 2 of the present invention.
As shown in FIG. 4A, the FPC 10 (flexible printed wiring board) exposes the base film 11, the wiring 12 (conductor layer) provided on the upper surface 11a side of the base film 11, and the tip of the wiring 12. However, the reinforcing plate 15 as in the first embodiment is not attached to the lower surface 11 b of the base film 11. The FPC 10 of the present embodiment also has a single-sided circuit type structure.
The materials and thicknesses of the base film 11, the wiring 12, and the coverlay 13 are the same as those in the embodiment.

Next, as shown in FIG. 4B, a reinforcing plate 15 and a rod-shaped spacer 16 are arranged on the lower die 21 using the same press die as in the first embodiment. Then, the FPC 10 is placed with the wiring 12 facing upward.
The thickness, shape, material, and the like of the reinforcing plate 15 and the spacer 16 are the same as those in the first embodiment. Note that an adhesive material is applied to the upper surface of the reinforcing plate 15 in advance.

Next, as shown in FIG. 4C, the base film 11 and the wiring 12 of the FPC 10 are deformed by press working for lowering the upper die 22 at a high speed. At this time, a part of the base film 11 and the wiring 12 is deformed by the hard spacer 16, and the convex portion 18 having a shape following the concave portion 22 a of the upper mold 22 is formed. Then, the spacer 16 is fitted into the concave portion 19 formed on the back side of the convex portion 18, and the reinforcing plate 15 is attached to the lower surface 11 b of the base film 11 with the spacer 16 interposed therebetween.
Note that heat may be applied to the FPC 10 or the like during pressing.

  The diameter of the spacer 16 is the same as in the embodiment, the outermost radius of curvature of the convex portion 18 is about 0.3 mm to 0.6 mm, and the width (front-rear direction) of the convex portion 18 is 0. It is about 8 mm to 1.5 mm.

  According to the FPC 10 and the method for forming the convex structure in the present embodiment, as in the first embodiment, the convex portion 18 from which the wiring 12 protrudes can be formed easily and quickly by a simple processing method called press processing. it can. In addition, as in the first embodiment, the spacer 16 fitted in the concave portion 19 serves to prevent the structure (convex structure) of the convex portions 18 of the base film 11 and the wiring 12 from being destroyed, so that the convex structure is ensured. The FPC 10 that can be held at the same time is obtained.

  In particular, in the present embodiment, since the reinforcing plate 15 is attached to the lower surface 11b of the base film 11 with the spacer 16 interposed therebetween, there is an advantage that the spacer 16 can be held more firmly than in the first embodiment. is there.

(Embodiment 3)
5A to 5C are cross-sectional views illustrating a method for forming a convex structure according to Embodiment 3 of the present invention.
As shown in FIG. 5A, the FPC 10 (flexible printed wiring board) has the wiring 12 and the coverlay 13 on the upper surface 11 a and the lower surface 11 b of the base film 11. That is, the FPC 10 of the present embodiment has a double-sided circuit type structure. In the present embodiment, the reinforcing plate 15 is not attached, but a reinforcing plate made of an insulating material may be attached on both sides.

  Next, as shown in FIG. 5B, it has a lower mold 21 in which a recess 21a extending in a direction perpendicular to the paper surface is formed, and an upper mold 22 in which a recess 22a extending in a direction perpendicular to the paper surface is formed. Using a press die, the reinforcing plate 15, the width direction of the base film 11 (direction perpendicular to the paper surface) and the adhesive sheet 17 are arranged on the lower die 21. The FPC 10 is placed with the wiring 12 facing upward, and a bar-like spacer 16 and an adhesive sheet 17 extending on the wiring 12 on the upper side of the FPC 10 in the width direction of the base film 11 (direction perpendicular to the paper surface). Is placed.

In this embodiment, since the spacer 16 is disposed on the wiring 12, it is preferable that the spacer 16 is made of an insulating material. However, when the spacer 16 and the wiring 12 can be reliably insulated by the adhesive sheet 17, it may be made of a conductive material.
At this time, the reinforcing plate 15 may be disposed so as to face the wiring 12 with the spacer 16 interposed therebetween.

  Next, as shown in FIG. 5C, the base film 11 and the wiring 12 of the FPC 10 are deformed by press working for lowering the upper die 22 at a high speed. At this time, a part of the base film 11 and the wiring 12 is deformed by the spacer 16 and protrudes upward in a shape following the recess 22a of the recess 22a of the upper mold 22, and the recess of the lower mold 22 The convex part 18 which protruded below in the shape which followed 21a is formed. Then, the spacers 16 are fitted into the respective concave portions 19 formed on the back side of the respective convex portions 18.

  According to the FPC 10 and the method for forming the convex structure in the present embodiment, the convex portion 18 from which the wirings 12 on both sides protrude is formed easily and quickly by using a simple processing method called press processing for the FPC 10 of double-sided circuit type. be able to. As in the first embodiment, the spacer 16 fitted in the concave portion 19 serves to prevent the structure (convex structure) of the convex portions 18 of the base film 11 and the wiring 12 from collapsing. The double-sided circuit type FPC 10 can be obtained.

  In the first embodiment, the press working is performed using the upper mold 22 having the recess 22a extending in the width direction of the base film 11, but the recess 22a is not necessarily required. This is because the convex portion 18 is formed only by pressing the portions corresponding to both sides of the spacer 16 with the upper mold 22 during the press working.

  The structure of the embodiment of the present invention disclosed above is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The present invention can be used not only for mobile phones but also for FPCs arranged in electronic devices such as cameras such as digital cameras and video cameras, portable audio players, portable DVD players, and portable notebook computers.

(A)-(c) is sectional drawing which shows the formation method of the convex structure which concerns on Embodiment 1 of this invention. It is a perspective view which shows the example which connects FPC shown in FIG.1 (c) to the existing connector. It is sectional drawing which shows the example which connects FPC shown in FIG.1 (c) directly to a motherboard. (A)-(c) is sectional drawing which shows the formation method of the convex structure which concerns on Embodiment 2 of this invention. (A)-(c) is sectional drawing which shows the formation method of the convex structure which concerns on Embodiment 3 of this invention.

Explanation of symbols

10 FPC
11 Base film 11a Front surface 11b Back surface 12 Wiring (conductor layer)
13 Coverlay 15 Reinforcement plate 16 Spacer 17 Adhesive sheet 18 Convex part 19 Concave part 21 Lower mold 21a Concave 22 Upper mold 22a Concave 30 Mother board 31 Substrate 32 Wiring 35 ACF
40 connectors

Claims (8)

A flexible printed wiring board comprising a base film and a conductor layer formed on the front surface of the base film,
A convex part extending in the width direction of the base film, the base film and the conductor layer projecting to the conductor layer side,
A rod-shaped or cylindrical spacer attached to a concave portion formed on the back side of the convex portion;
A flexible printed wiring board. In the flexible printed wiring board according to claim 1,
It further includes a reinforcing plate attached to the back surface of the base film,
The convex portion and the concave portion are formed on the base film, the conductor layer and the reinforcing plate,
The said spacer is a flexible printed wiring board attached to the recessed part formed in the said reinforcement board. In the flexible printed wiring board according to claim 1,
The flexible printed wiring board further provided with the reinforcement board affixed on the said back surface of the said base film on both sides of the said spacer. In the flexible printed wiring board according to claim 1,
Further comprising another conductor layer formed on the back surface of the base film,
The convex part and the concave part are formed in the base film, the conductor layer and another conductor layer,
Another convex part extending in the width direction of the base film, the base film, a conductor layer and another conductor layer projecting toward the another conductor layer;
Another rod-shaped or cylindrical spacer attached to another concave portion formed on the back side of the other convex portion;
A flexible printed wiring board. A method of forming a convex structure on a flexible printed wiring board comprising a base film and a conductor layer formed on the front surface of the base film,
Placing a rod-like or cylindrical spacer extending in the width direction on the back side of the base film (a);
After the step (a), the step (b) of deforming the base film and the conductor layer by press working with the spacer interposed therebetween;
A method for forming a convex structure of a wiring board including: In the formation method of the convex structure of the wiring board of Claim 5,
Before the step (a), further comprising a step of attaching a reinforcing plate to the back surface of the base film,
In the step (b), a method of forming a convex structure of a wiring board, wherein the base film, the conductor layer, and the reinforcing plate are deformed by pressing with the spacer interposed therebetween. In the formation method of the convex structure of the wiring board of Claim 5,
After the step (a) and before the step (b), further comprising a step of arranging a reinforcing plate on the back side of the base film with the spacer interposed therebetween,
In the step (b), a method for forming a convex structure of a wiring board, wherein the base film and the conductor layer are deformed by press working with the reinforcing plate and spacer interposed therebetween. In the formation method of the convex structure of the wiring board of Claim 5,
In the step (a), another bar-shaped or cylindrical spacer extending in the width direction is disposed on the front surface side of the base film,
In the step (b), a method for forming a convex structure of a wiring board, wherein the base film and the conductor layer are deformed by pressing while sandwiching the spacer and another spacer.

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