JP2006237320A - Flexible mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manageable flexible mounting substrate having an improved bending resistance, requiring no special caution in the handling thereof after the mounting of an electronic component, and having less possibility of wire breaking. <P>SOLUTION: This flexible mounting substrate comprises: a flexible base 3 formed of an insulating material; a conductor film 4 having a predetermined pattern formed of an electrically conductive material provided on the flexible base 3; and a protective film 5 having openings 9, 10 for exposing predetermined portions of the flexible base 3 and the conductor film 4 and covering the flexible base 3 and the conductor film 4. Lands 6a, 6b for mounting LEDs 2 adjacently to each other with a spacing between them are plurally provided in the opening 9, respectively. Respective lands 6a, 6b are connected by connecting wiring 7 or 13 extending from one of them in the direction different from the adjacency direction between the corresponding lands, and reaching the corresponding other land. At least a part of the intermediate portion of the connecting wiring 7 or 13 is covered with the protective film 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flexible mounting board suitable for mounting electronic components at high density.

  As is well known, the mounting of electronic components in electronic devices uses flexible mounting boards and reduces the distance between the electronic components in response to demands for higher functionality, smaller size, and thinner devices. Densification is performed. For example, a liquid crystal display unit having a configuration in which electronic components such as a plurality of LEDs (light emitting diodes) are arranged close to each other, and the adjacent terminals corresponding to each other are connected to each other by connection wiring, and the LEDs are connected in series. In the case of a personal digital assistant (PDA) provided, the mounting state is as shown in FIG. 4 and FIG. FIG. 4 is a side view schematically showing a liquid crystal display portion of the PDA, and FIG. 5 is a plan view of a flexible mounting board on which LEDs are mounted.

  That is, in FIGS. 4 and 5, reference numeral 100 denotes a liquid crystal display portion of the PDA, which is composed mainly of a liquid crystal display element 101 and a front light 102 that illuminates the liquid crystal display element 101. The front light 102 has a light emitting surface 104a with respect to a substantially rectangular light guide plate 103 disposed on a viewing side surface of the liquid crystal display element 101 and a light incident surface 103a on a side surface substantially orthogonal to the viewing direction of the light guide plate 103. A light source including a plurality of LEDs 104 arranged to face each other is provided. In addition, the plurality of LEDs 104 are connected to each other between adjacent terminals so that adjacent LEDs are juxtaposed on the flexible mounting substrate 105 and juxtaposed in the longitudinal direction of the light incident surface 103a of the light guide plate 103. Connected in series. Reference numeral 106 denotes a wiring board arranged on one side of the liquid crystal display element 101. The board 106 is mounted with a driver IC for driving the liquid crystal display element 101, a power supply circuit for lighting the LED 104, and the like. One end side of the flexible mounting board 105 on which the LED 104 is mounted on the wiring board 106 is electrically connected and fixed by an anisotropic conductive adhesive or the like.

  The LED 104 and the light guide plate 103 are configured such that the light emission surface 104 a of the LED 104 faces the light incident surface 103 a of the light guide plate 103 and light emitted from the LED 104 is directly introduced into the light guide plate 103.

  In general, the light emitted from the LED 104 is excellent in straightness, and in such a configuration, uneven brightness is a concern. If the occurrence of uneven brightness is a concern, in that case, the occurrence of uneven brightness can be suppressed by increasing the number of LEDs 104 to be used or adopting the configuration shown in FIG. It becomes possible.

  That is, in FIG. 6, a sub light guide plate 114 provided with a prism (not shown) or the like is disposed facing the light incident surface 103 a side of the light guide plate 103, and is different from the light emission surface of the sub light guide plate 114. A plurality of LEDs 104 are arranged to face both side surfaces.

  By adopting such a configuration, the light emitted from each LED 104 is introduced into the sub light guide plate 114 from the side surface of the sub light guide plate 114, and is guided in a uniform manner by the prism action or the like of the sub light guide plate 114. Derived from the light exit surface side facing the light incident surface 103a of the light plate 103.

  Therefore, the sub light guide plate 114 operates as if it functions as a linear light source, and can supply the light guide plate 103 with emission light with little or no luminance unevenness.

  The flexible mounting substrate 105 includes a flexible substrate 107, a conductor film 108 having a predetermined pattern provided on the flexible substrate 107, and a protective film 109 covering the flexible substrate 107 and the conductor film 108. . The conductor film 108 is formed with lands 110 for mounting the LED 104 of the electronic component, connection wirings 111 for connecting the lands 110, and the like, and the protective film 109 is required for the lands 110, the connection wirings 111, and the like. Openings 112 and 113 are formed so that the portions are exposed.

  In this circuit pattern, since the two LEDs 104 are arranged close to each other, the distance between the lands 110 for fixing the corresponding terminal portions of the respective LEDs 104 is narrow, so the two lands 110 are connected in series. The protective film 109 cannot be provided on the connecting wiring 111 to be connected, and the two lands 110 are exposed in the same opening 112. Further, the connection wiring 111 that connects the lands 110 does not cause the solder to evenly adhere to the lands 110 or cause the misalignment of the mounted LEDs 104 when solder reflow for mounting the LEDs 104 is performed. A so-called H-shaped pattern of the conductive film 108 is formed in the opening 112. Such a conductor film having an H-shaped pattern is also found in other prior arts (see, for example, Patent Document 1).

However, in the above prior art, since the LED 104 is mounted on the flexible mounting board 105, it is necessary to pay attention to handling after mounting electronic parts, especially when careless handling or handling errors occur. The flexible mounting substrate 105 may be twisted or bent at a portion where the flexible mounting substrate 105 is easily bent due to a lateral stress applied to the electronic component or the like, or its own weight. This stress, bending stress, etc. are particularly likely to be applied to the thin wiring pattern 111 connecting the lands 110. If the stress, bending stress, etc. are excessive or repeatedly applied, the connection wiring 111 breaks and connects. There is a possibility that the wiring 111 is disconnected and the LED 104 cannot be turned on.
Japanese Patent Laying-Open No. 2003-8154 (FIG. 14)

  The present invention has been made in view of the situation as described above, and the object thereof is good bending resistance, and it is not necessary to pay special attention in handling after mounting electronic components, An object of the present invention is to provide a flexible mounting substrate that is easy to handle with little risk of disconnection, enables high-density mounting of electronic components, and can reduce the size and thickness of the device.

  The flexible mounting substrate of the present invention includes a flexible substrate formed of an insulating material, a conductor film having a predetermined pattern formed of a conductive material provided on the flexible substrate, and a predetermined portion of the flexible substrate and the conductor film. A flexible mounting substrate provided with an opening so as to be exposed and a protective film covering the flexible substrate and the conductor film, wherein the opening for mounting electronic components mounted adjacent to each other is provided in the opening, Each land is provided with a plurality of spaced apart, and each land is connected by a connection wiring extending from one of the corresponding lands to a direction different from the adjacent direction to another corresponding land, And at least one part of the intermediate part of this connection wiring is covered with the said protective film, It is characterized by the above-mentioned.

  As is clear from the above description, according to the present invention, the bending resistance is good, and it is not necessary to pay special attention in handling after mounting electronic components, and there is little risk of disconnection. It is easy to handle, enables high-density mounting of electronic components, and has the effect of enabling downsizing and thinning of equipment.

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

  First, a first embodiment will be described with reference to FIGS. FIG. 1 is a perspective view of a flexible mounting substrate showing a state where electronic components are mounted, and FIG. 2 is a plan view of the main part thereof.

  In FIG. 1 and FIG. 2, a flexible mounting substrate 1 is mounted so that a plurality of LEDs (light emitting diodes) 2 are connected in series and arranged close to each other, as in the prior art, and not shown, but a personal digital assistant (PDA) The front light which illuminates the liquid crystal display element provided in this liquid crystal display part is comprised.

  The flexible mounting substrate 1 is, for example, a conductive foil formed of a metal material such as a copper foil having a thickness of about 18 μm on the upper surface of a flexible substrate 3 having a thin plate structure made of an insulating material such as a polyimide film having a thickness of about 12.5 μm Is provided with a conductor film 4 having a predetermined pattern, and a part of the flexible substrate 3 and the conductor film 4 is left, and a polyimide film having a thickness of about 12.5 μm is formed so as to cover the upper surface thereof. A protective film 5 made of an insulating material is provided. Although not shown, the conductor film 4 having a predetermined pattern is formed by providing an adhesive layer having a thickness of about 10 μm on the upper surface of the flexible substrate 3, fixing a conductive foil thereon, and further patterning the conductive foil. The protective film 5 is fixed by providing an adhesive layer having a thickness of about 25 μm.

  In addition, rectangular lands 6 a and 6 b for connecting two LEDs 2 in series for mounting are formed on the conductor film 4 in correspondence with the respective LEDs 2. The lands 6a and 6b corresponding to the respective LEDs 2 are formed so as to be close to each other as long as the two LEDs 2 can be mounted, for example, with a gap of about 1.2 mm to 1.5 mm between the two LEDs 2. ing. Further, of the four lands 6a and 6b corresponding to the connection terminals of the LEDs 2, when the LEDs 2 are connected in series, the land 6a corresponding to one LED 2 to be conductively connected and the land 6b corresponding to the other LED 2 are: A predetermined small interval, for example, about 0.6 mm is provided between adjacent sides so as to be adjacent to each other.

  Also, between two adjacent lands 6a and 6b disposed with a small gap therebetween, the first connection wiring 7 formed in the conductor film 4 so as to be narrower than both lands 6a and 6b. The second connection wiring 8 is branched and connected to two systems. The first connection wiring 7 has a substantially square shape, and one end side extends from a side different from the opposite side of the land 6a in a direction orthogonal to the adjacent direction, and the other end side is different from the opposite side of the land 6b. It extends from the side in the same orthogonal direction as described above with respect to the adjacent direction, and is formed from an extending portion in the adjacent direction so as to return to the other land by folding back to the intermediate portion. The second connection wiring 8 is provided between the opposing sides of the two lands 6a and 6b so as to extend in a substantially adjacent direction which is the shortest direction in a narrower pattern than the shape of the lands 6a and 6b. ing.

  On the other hand, openings 9 and 10 are formed in the protective film 5 so that the lands 6a and 6b for mounting the LED 2, a part of the first connection wiring 7, and the second connection wiring 8 are exposed. It is provided so as to cover the upper surface of the conductor film 4 having a predetermined pattern in which the remaining wiring (not shown) and the like are formed and the conductor film 4 is not present.

  Accordingly, in one opening 9 of the protective film 5, two adjacent lands 6 a, 6 b and the second connection wiring 8 are exposed with a small interval, and one of the first connection wirings 7 is exposed. The extended portions from the two lands 6a and 6b, which are the portions, are exposed. Many portions of the intermediate portion including the folded portion of the first connection wiring 7 are covered with the protective film 5. In the other opening 10, other lands 6 a and 6 b for connecting the corresponding LED 2 are exposed.

  As described above, the first connection wiring 7 that connects the two lands 6a and 6b exposed in the same opening 9 extends in a substantially adjacent direction that is the substantially shortest distance between the lands 6a and 6b. Therefore, even when the LEDs 2 are arranged close to each other, the intermediate portion of the wiring can be covered with the protective film 5, and the strength (bending resistance) against the stress and bending stress on the first connection wiring 7 becomes strong. . For this reason, even if stress or repeated bending stress is applied to the flexible mounting substrate 1 and the second connection wiring 8 connecting the lands 6a and 6b at a substantially shortest distance is disconnected, the second connection wiring 8 is disconnected. Connection by the 1 connection wiring 7 is ensured, and generation | occurrence | production of malfunctions, such as non-lighting of LED2 by a disconnection etc., can be prevented.

  Even after the LED 2 and other electronic components are mounted, it is not necessary to pay special attention to the handling of the flexible mounting board 1. Furthermore, since the two LEDs 2 or other electronic components can be arranged closer to each other, they can be mounted at a high density, and the incorporated device can be made smaller and thinner.

  Further, the first connection wiring 7 and the second connection wiring 8 are arranged in different directions from the lands 6a and 6b, and the middle portion of the first connection wiring 7 in which both the wirings 7 and 8 are in the same direction. Since the (folded portion) is covered with the protective film 5, even if the connection wiring 7 or 8 on one side is subjected to stress or stress applied from one direction, the connection wiring 8 on the other side. Since 7 or 7 has a small influence, it is possible to improve the stress and the ability to cope with the stress, and it is also possible to produce an effect that can effectively prevent the occurrence of problems such as non-lighting of the LED 2. It becomes.

  Next, a second embodiment will be described with reference to FIG. FIG. 3 is a plan view of the main part. As in the first embodiment, this embodiment constitutes a front light that illuminates the liquid crystal display element by mounting a plurality of LEDs in series connection, and is the same as the first embodiment. The components are denoted by the same reference numerals, description thereof is omitted, and the configuration of the present embodiment that is different from the first embodiment will be described.

  In the second embodiment shown in FIG. 3, the second connection wiring 8 in the first embodiment is basically omitted, and adjacent to each other with a small interval between them. The two lands 6a and 6b are connected to the conductor film 12 by a connection wiring 13 formed narrower than both the lands 6a and 6b. The connection wiring 13 has a substantially square shape, and one end side extends from a side different from the opposite side of the land 6a in a direction perpendicular to the adjacent direction, and the other end side is adjacent to a side different from the opposite side of the land 6b. It extends in the same direction as described above perpendicular to the direction, and is formed from an extending portion in the adjacent direction so as to return to the other land by folding back to the middle portion.

  On the other hand, openings 9 and 10 are formed in the protective film 5 so that the lands 6a and 6b for mounting the LED 2 and a part of the connection wiring 13 are exposed, and the remaining wiring and the like (not shown) are formed. The conductive film 12 having a predetermined pattern and the upper surface of the flexible substrate 3 where the conductive film 12 does not exist are provided.

  In one opening 9 formed in this manner, there are extended portions from two lands 6a and 6b that are a part of the two lands 6a and 6b adjacent to each other and the connection wiring 13 with a small interval. Exposed. Many portions of the intermediate portion including the folded portion of the connection wiring 13 are covered with the protective film 5. In the other opening 10, other lands 6 a and 6 b for connecting the corresponding LED 2 are exposed.

  As described above, the connection wiring 13 that connects the two lands 6a and 6b exposed in the same opening 9 does not extend in the substantially adjacent direction that is the substantially shortest distance between the two lands 6a and 6b. Since it extends in a direction intersecting the substantially adjacent direction and reaches the other land, the intermediate portion of the connection wiring 13 can be covered with the protective film 5 even when the LEDs 2 are arranged close to each other. No. 13 has a strong strength (bending resistance) against stress and bending stress. As a result, even if stress or bending stress is applied to the flexible mounting substrate 1, the stress or bending stress is suppressed by the protective film 5, and even if the connecting wiring 13 portion is formed to be narrower than the lands 6a and 6b, this portion Is less likely to break, and it is possible to prevent the occurrence of problems such as non-lighting of the LED 2 due to breakage or the like.

  Even after the LED 2 and other electronic components are mounted, it is not necessary to pay special attention to the handling of the flexible mounting board 1. Further, since the two LEDs 2 or other electronic components can be arranged closer to each other, high-density mounting can be performed, and the equipment to be incorporated can be made smaller and thinner.

  In each of the above-described embodiments, the first connection wiring 7 and the connection wiring 13 that connect the two lands 6a and 6b adjacent to each other with a small interval are formed in a substantially square shape. However, the present invention is not limited to this. Rather than a pattern that connects at the shortest distance in the adjacent direction, such as a substantially U-shape or a substantially V-shape, a detour that extends from one land in a direction intersecting the adjacent direction and reaches the other land The same effect can be obtained by forming the pattern to be covered and covering the intermediate portion with the protective film 5 or forming the pattern portion covered with the protective film 5 with a narrower width.

  Further, the electronic component connected between the lands 6a and 6b is not limited to the LED 2, and may be other chip components or discrete components. Furthermore, although the case where the electronic components are connected in series is described, when the lands 6a and 6b connected by the connection wires 7, 8, and 13 are used as a common connection point, the electronic components are connected in parallel. Can also be applied. Furthermore, when there is a space in a direction orthogonal to the adjacent direction of the lands 6a and 6b, the connection wirings 7 and 13 are arranged not only on one side but also on both sides to further strengthen the stress and stress. It is also possible to configure as above.

It is a perspective view which shows the state which mounted the electronic component in the flexible mounting board | substrate in the 1st Embodiment of this invention. It is a top view which shows the principal part in the 1st Embodiment of this invention. It is a top view which shows the principal part in the 2nd Embodiment of this invention. It is a side view which shows typically the liquid crystal display part of PDA which concerns on a prior art. It is a top view which shows the state which mounted the electronic component in the flexible mounting board | substrate in a prior art. It is a top view which shows typically the front light structure in a prior art.

Explanation of symbols

1 ... Flexible mounting board 2 ... LED
DESCRIPTION OF SYMBOLS 3 ... Flexible base | substrate 4,12 ... Conductor film 5 ... Protective film 6a, 6b ... Land 7 ... 1st connection wiring 8 ... 2nd connection wiring 9, 10 ... Opening part 13 ... Connection wiring

Claims (3)

  A flexible substrate formed of an insulating material, a conductor film having a predetermined pattern formed of a conductive material provided on the flexible substrate, and an opening so as to expose a predetermined portion of the flexible substrate and the conductor film A flexible mounting board provided with a protective film covering the flexible substrate and the conductor film, wherein a plurality of lands for mounting electronic components mounted adjacent to each other are provided in the opening in a spaced manner And each land is connected by a connection wiring extending from one of the lands to a corresponding other land extending in a direction different from the adjacent direction between the corresponding lands. A flexible mounting board, wherein at least a part of an intermediate part is covered with the protective film.   The flexible mounting board according to claim 1, wherein the lands are connected by a connection wiring different from the connection wiring extending in a substantially adjacent direction between the corresponding lands.   The flexible mounting board according to claim 1, wherein the connection wiring has a narrower width than each land to which the connection wiring is connected.

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