JP2007027422A - Flexible printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed circuit board which can realize junction to a rigid printed board by a constitution of high junction strength and space saving without using an additional member such as a fastening member. <P>SOLUTION: A flexible printed circuit board 100 has an annular part 100a with a hole 103 in one end side, and a liner part 100b in the other end side. The annular part 100a is joined to a rigid board, and the linear part 100b has a signal extractor in its tip. The annular part 100a has three copper foil exposure portions 104 wherein one flexible film 102 is cut out in a regulated part of the hole 103 in one end side, and has two exposure portions 104a for junction wherein one flexible film 102 and a copper foil pattern 101 are cut out in both sides thereof. The copper foil exposure 104 of the flexible printed circuit board 100 is joined to a copper foil exposure of the ridge board, and the exposure 104a for junction of the flexible printed circuit board 100 is joined to a rigid board each by soldering. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible printed circuit board, and more particularly to a flexible printed circuit board connected to a rigid printed circuit board incorporated in an electronic apparatus.

  2. Description of the Related Art In recent years, electronic devices such as digital cameras and notebook personal computers have been remarkably improved in functionality, and are equipped with a large number of electrical components such as switches and large liquid crystal panels. With the demand for miniaturization of these electronic devices, the need for high-density mounting of electrical components is increasing.

  Such electrical components are arranged at various positions in the electronic device depending on the design and operability of the electronic device. Therefore, a flexible printed circuit board (hereinafter referred to as “flexible circuit board”) is generally used to electrically connect these electric components.

  In addition, there is a rigid printed circuit board (hereinafter referred to as “rigid circuit board”) equipped with a control circuit for each switch and a circuit for driving a liquid crystal in the electronic device, and the rigid circuit board and the flexible circuit board are electrically connected. .

As a conventional technique for connecting a rigid board and a flexible board, there is a technique in which a rigid board and a flexible board are fastened using a fastening member (see, for example, Patent Document 1).
JP-A-8-116145

  However, the above conventional technique requires a fastening member for fastening the rigid board and the flexible board, and thus has a problem that the number of parts increases and the cost increases.

  Further, in the conventional technology, not only the electrical connection portion of the flexible board but also the signal lead-out portion of the flexible board is almost in contact with the rigid board. Therefore, mounting components are placed on the rigid board where the signal lead-out portion is almost in contact. Can not be placed.

  An object of the present invention is to provide a flexible printed circuit board that can be bonded to a rigid printed circuit board with a high bonding strength and a space-saving configuration without using an additional member such as a fastening member.

  In order to achieve the above object, a flexible printed circuit board according to claim 1 is a flexible printed circuit board connected to a rigid printed circuit board. The flexible printed circuit board has an annular portion with a hole in one end and a straight line in the other end. And the annular portion is joined to the rigid printed circuit board at the hole defining portion on the one end side.

  According to the present invention, since the hole defining portion on the one end side of the annular portion of the flexible printed circuit board is bonded to the rigid printed circuit board, high bonding strength and space saving can be achieved with the rigid circuit board without using an additional member such as a fastening member. Can be joined in a simple configuration.

  Preferably, the annular portion of the flexible printed circuit board is configured to be engaged with the support member together with the rigid printed circuit board on the other end side, so that the flexible printed circuit board and the rigid printed circuit board can be positioned.

  Preferably, since it is folded back 180 ° in the vicinity of the boundary between the annular portion and the linear portion of the flexible printed circuit board, a mounting component can be mounted on the rigid printed circuit board below the linear portion, and thus an unmountable region due to bonding of the bonding material High mounting efficiency can be achieved with a space-saving configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view schematically showing a configuration of a flexible substrate according to an embodiment of the present invention.

  In FIG. 1, a flexible substrate 100 cooperates with one flexible film 102 made of polyimide, a copper foil pattern 101 formed by etching on one flexible film 102, and one flexible film 102. And the other flexible polyimide film 102 that sandwiches the copper foil pattern 101.

  In addition, the flexible substrate 100 has an annular portion 100a having a hole 103 on one end side, and a linear portion 100b on the other end side. The annular portion 100a is joined to a rigid substrate 200, which will be described later, and the straight portion 100b has a signal extraction portion at the tip thereof.

  Furthermore, the annular portion 100a has three copper foil exposed portions 104 (joined portions) in which one flexible film 102 is cut out in the defining portion of the hole 103 on one end side, The flexible film 102 and the copper foil pattern 101 have two exposed exposed portions 104a (joined portions) cut out, and these exposed portions are arranged at equal intervals.

  The copper foil pattern 101 is formed in a linear shape from the three copper foil exposed portions 104 to the annular portion 100a and the straight portion 100b, and is formed to the signal lead-out portion at the tip of the straight portion 100b.

  FIG. 2 is a perspective view of the flexible substrate 100 of FIG. 1 bonded to a rigid substrate.

  In FIG. 2, a rigid substrate 200 includes a base material such as one glass cloth base material epoxy resin, a copper foil pattern formed by etching on a base material such as one glass cloth base material epoxy resin, and one glass glass. And the other insulating layer sandwiching the copper foil pattern in cooperation with a base material such as a cloth base material epoxy resin.

  The rigid substrate 200 has a copper foil exposed portion 204 in which the other insulating layer used for electrical connection with the flexible substrate 100 is cut off at a predetermined position to expose the copper foil pattern. Has a plurality of exposed portions corresponding to the number of signals to be electrically connected.

  In FIG. 2, the copper foil exposed portion 104 of the flexible substrate 100 is electrically connected to the copper foil exposed portion 204 of the rigid substrate 200 by the solder 300, and the rigid substrate 200 is connected to the exposed portion 104 a for joining the flexible substrate 100. Are joined by solder 300 (joining material).

  FIG. 3 is a partial cross-sectional view of the flexible substrate 100 in FIG. 2, and shows a case where an external force in a direction substantially perpendicular to the joint surface with the rigid substrate 200 acts on the flexible substrate 100.

  In FIG. 3, the copper foil exposed portion 104 of the flexible substrate 100 is electrically connected to the copper foil exposed portion 204 of the rigid substrate 200 by solder 300, and the exposed portion 104 a for bonding of the flexible substrate 100 is connected to the rigid substrate 200. Bonded by solder 300.

  According to the present embodiment, in FIG. 3, for example, when the external force 1 acts on the flexible substrate 100 as illustrated in the assembly process of the electronic device, the flexible substrate 100 bends to serve as a buffer. The impact external force 2 applied to the solder 300, that is, the impact load peeled off from the copper foil exposed portion 204 of the rigid board 200 is weakened, and the electrical connection is not broken without the solder 300 being peeled off. Even if a stronger external force 1 is applied to the flexible substrate 100, first, the solder 300 that joins the exposed portions 104a on both outer sides is peeled off from the rigid substrate 200, or the solder 300 is cracked. Therefore, there is no effect on the solder 300 that connects the exposed copper foil pattern 101 for signal connection, and the electrical connection is not broken.

  In addition, according to the present embodiment, there is no need for a fastening member that is an additional member for fastening the flexible substrate 100 and the rigid substrate 200, which has been necessary in the past, so that the number of parts and cost can be reduced. . Furthermore, since the electrical connection can be performed only by the solder 300, the flexible substrate 100 can be replaced only by melting the solder 300, and the replacement cost can be reduced.

  FIG. 4 is a perspective view of a modification of the flexible substrate 100 in FIG.

  The configuration of this modification is basically the same as that of FIG. 2, and the same components are denoted by the same reference numerals and redundant description is omitted, and only different points will be described below.

  In FIG. 4, the flexible substrate 100 is bonded to the rigid substrate 200 and supported by the support member 400 together with the rigid substrate 200. The support member 400 is a resin molded product.

  The flexible substrate 100 has a pair of through holes 105 at both ends on the other end side of the annular portion 100 a, and similarly, the rigid substrate 200 has a pair of through holes 205 corresponding to the through holes 105. The support member 400 has two protrusions 401.

  The support member 400 supports the rigid substrate 200 so that the through hole 205 is fitted to the projection 401, and supports the flexible substrate 100 so that the through hole 105 is also fitted to the projection 401. The flexible substrate 100 and the rigid substrate are supported by the support member 400. It becomes a reference for positioning of the joint with 200.

  According to this modification, the flexible substrate 100 and the rigid substrate 200 can be supported and positioned by the protrusions 401 of the support member 400, so that the copper foil exposed portions 104 of the flexible substrate 100 and the rigid substrate 200 can be positioned. When joining 204 with the solder 300, the positional accuracy in the pitch direction of the copper foil exposed portions 104, 204 between the flexible substrate 100 and the rigid substrate 200 can be increased, and the plurality of exposed portions do not short-circuit between adjacent ones. The workability of joining with the solder 300 can be improved. Furthermore, it is possible to deal with the gorge pitch, and even if the number of signals is increased, it is possible to provide a joint with the solder 300 that saves space.

  FIG. 5 is a partial cross-sectional view of the flexible substrate 100 in FIG. 4, and shows a case where an external force in a direction substantially perpendicular to the bonding surface with the rigid substrate 200 acts on the flexible substrate 100.

  In FIG. 5, the flexible substrate 100 is bonded to the rigid substrate 200 and supported by the protrusion 401 of the support member 400 together with the rigid substrate 200.

  In FIG. 5, for example, when an external force 1 acts on the flexible substrate 100 as shown in the assembly process of the electronic device, first, the through hole 105 of the flexible substrate 100 first extends in the direction in which the protrusion 401 of the support member 400 is removed. However, since the copper foil exposed portion 104 of the flexible substrate 100 is joined to the copper foil exposed portion 204 of the rigid substrate 200 by the solder 300, it is not pulled out in the direction in which the protrusion 401 of the support member 400 is removed. Therefore, no stress is applied to the solder 300 and the electrical connection is not broken.

  FIG. 6 is a partial cross-sectional view of another modification of the flexible substrate 100 in FIG.

  In FIG. 6, the flexible substrate 100 is bonded to the rigid substrate 200 and supported by the protrusion 401 of the support member 400 together with the rigid substrate 200.

  Further, the flexible substrate 100 is configured to be folded back 180 ° with the vicinity of the boundary between the annular portion 100a and the straight portion 100b as a fulcrum.

  According to this modification, since the signal lead-out portion of the flexible substrate 100 is folded back 180 °, the mounting component 500 can be mounted on the rigid substrate 200 other than the annular portion 100a of the flexible substrate 100 in contact with the rigid substrate 200. In addition, it becomes possible to minimize the unmountable area due to the joining of the solder 300, and high mounting efficiency can be achieved with a space-saving configuration.

It is a perspective view showing roughly the composition of the flexible substrate concerning the embodiment of the present invention. It is a perspective view of the flexible substrate of FIG. 1 joined to a rigid substrate. It is a fragmentary sectional view of the flexible substrate in FIG. 2, and shows the case where the external force of a substantially perpendicular direction acts with respect to a joint surface with a rigid substrate on a flexible substrate. It is a perspective view of the modification of the flexible substrate in FIG. FIG. 5 is a partial cross-sectional view of the flexible substrate in FIG. 4, showing a case where an external force in a direction substantially perpendicular to the joint surface with the rigid substrate acts on the flexible substrate. It is a fragmentary sectional view of the other modification of the flexible substrate in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Flexible printed circuit board 101 Copper foil pattern 102 Flexible film 103 Hole 104,204 Copper foil exposure part 105,205 Through-hole 200 Rigid printed circuit board 300 Solder 400 Support member 401 Protrusion 500 Mounting component

Claims (11)

In flexible printed circuit boards connected to rigid printed circuit boards,
It has an annular part with a hole on one end side and a linear part on the other end side, and the annular part is joined to the rigid printed circuit board at a hole defining part on the one end side. Flexible printed circuit board.   The flexible printed circuit board according to claim 1, wherein the annular portion is configured to be engaged with a support member together with the rigid printed circuit board on the other end side.   The said support member has a pair of protrusion, The said cyclic | annular part has a pair of through-hole which fits into a pair of protrusion of the said support member in the said other end side. Flexible printed circuit board.   The flexible printed circuit board according to any one of claims 1 to 3, wherein the flexible printed circuit board is folded 180 ° in the vicinity of a boundary between the annular portion and the straight portion.   One flexible insulator, a conductor pattern formed by etching on the one flexible insulator, and the conductor pattern in cooperation with the one flexible insulator. The flexible printed circuit board according to any one of claims 1 to 4, wherein the flexible printed circuit board comprises the other flexible insulator.   The flexible printed circuit board according to claim 5, wherein the conductor pattern is a copper foil pattern, and the flexible insulator is a flexible film.   The flexible printed circuit board according to claim 1, wherein the annular portion is bonded to the rigid printed circuit board by a bonding material.   In the annular portion, one of the flexible insulators is cut out as a plurality of joining portions in the hole defining portion on the one end side, and the joining material is joined to the rigid printed circuit board at these joining portions. The flexible printed circuit board according to claim 7.   In the annular portion, on both sides of the plurality of joint portions, one of the flexible insulators and the conductor pattern are cut out as a plurality of other joint portions. The flexible printed circuit board according to claim 8, wherein the flexible printed circuit board is bonded to a rigid printed circuit board.   The flexible printed circuit board according to claim 7, wherein the bonding material is solder.   The flexible printed circuit board according to claim 1, wherein the straight line portion includes a signal lead-out portion that extracts a signal at a tip thereof.

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