JP2007207782A - Composite flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive composite FPC with little waste wherein regions with different interconnection functions have high performances respectively. <P>SOLUTION: A first partial flexible substrate 10 and a second partial flexible substrate 20 are fabricated separately and are joined together with different materials for an insulating base material, different interconnection materials, and different interconnection rules. Thus, the partial flexible substrates having different interconnection functions are joined together to obtain the composite FPC having a targeted structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible printed wiring board (hereinafter referred to as FPC), and more particularly to a composite flexible printed wiring board (hereinafter referred to as composite FPC) formed by joining a plurality of partial flexible substrates.

  In recent years, electronic devices have been increased in frequency, digitized, and downsized. In connection with this, the printed wiring board used for an electronic device is requested | required that fine pitch reduction, size reduction, high-density mounting, and the freedom degree of installation are excellent. In particular, printed wiring boards used in portable electronic devices such as digital cameras, mobile phones, calculators, portable personal computers, and liquid crystal televisions are becoming smaller and more complicated in shape, and FPC is indispensable. It has become. Furthermore, when there is a mechanically movable part in the electronic device, wiring cannot be performed unless it is an FPC.

  Conventionally, in order to manufacture such an FPC, a plurality of formation regions are set on one insulating sheet, a wiring layer, a cover layer, and the like are sequentially formed on each forming region, and then, from one insulating sheet, A plurality of FPCs are taken out.

By the way, as a technique for connecting FPCs to each other, a device is known in which a connection allowance of at least twice the length necessary for connection is secured in the connection part of each FPC (for example, Patent Document 1).
Japanese Utility Model Publication No. 7-42594

  When an FPC is manufactured as described above, a plurality of FPCs are taken out from one insulating sheet. Therefore, when the shape of the FPC is complicated, the number of FPCs taken out per area is reduced and the material is wasted. There was a problem of becoming.

  Further, in the conventional manufacturing method, in order to satisfy some required characteristics of the FPC, it is necessary to manufacture the entire FPC using a material for satisfying the required characteristics. For example, when rough patterns and fine patterns are mixed in the FPC, it is necessary to use thin copper foil CCL (copper-clad laminate) so that the fine pattern can be etched. It was a factor of increase.

  Accordingly, an object of the present invention is to provide a composite FPC having high performance in each region having different wiring functions, low waste, and low cost.

  The gist of the composite FPC of the present invention is that a plurality of partial flexible boards having different wiring functions are joined to each other in a state where they are assembled in a target structure. Here, when the cases where the wiring functions are different are listed, when the constituent materials of the insulating base materials are different from each other, when the wiring rules are different, when the number of wiring layers is different, when the degree of flexibility is different, the manufacturing difficulty level is different. If they are different, the constituent material of the surface coating layer may be different, or may have different shapes.

  According to the present invention, since a plurality of partial flexible substrates having different wiring functions are joined so as to be conductive in a state where they are assembled to the target structure, there is no need to manufacture the target structure as a single substrate. Partial flexible substrates having different wiring functions can be manufactured separately. For this reason, it can manufacture according to each standard etc. of each partial flexible substrate from which a wiring function differs. Therefore, the individual performance of each partial flexible substrate can be enhanced. Further, by manufacturing according to the standard of each partial flexible substrate, waste is reduced, the composite FPC can be stably produced, and the yield can be improved.

  According to the present invention, since it has a flexible structure as a whole as a joined part of a partial flexible substrate having various functions, for example, it can be easily incorporated into an electronic device such as a mobile phone or a portable terminal device, and can be assembled. Improvement in space, space saving, and improvement in installation flexibility.

  Hereinafter, details of the composite FPC according to the embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic and the thicknesses and ratios of the material layers are different from the actual ones. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(First embodiment)
1 to 3 show a composite FPC 1 according to a first embodiment of the present invention. 1 is a perspective view of a main part showing the composite FPC 1, FIG. 2 is a cross-sectional view showing a state in which the connection terminal part showing the connection part of the composite FPC 1 is cut, and FIG. 3 is shown in FIG. It is sectional drawing which shows the state which bent one partial flexible substrate.

  The composite FPC 1 according to the present embodiment is generally configured by joining a first partial flexible substrate 10 having a relatively low degree of flexibility and a second partial flexible substrate 20 having a relatively high degree of flexibility. ing.

  As shown in FIGS. 1 to 3, the first partial flexible substrate 10 includes an insulating base material 11 having a relatively low degree of flexibility, and a wiring pattern formed on one surface of the insulating base material 11. 12 and a cover layer (protective layer) 13 that covers the surface of the insulating base material 11 on which the wiring pattern 12 is formed.

  In the present embodiment, polyimide is used as a constituent material of the insulating base material 11. The wiring pattern 12 is formed by patterning, for example, an electrolytic copper foil. Further, the wiring pattern 12 has a plurality of connection terminal portions 12 </ b> A drawn around the end portion of the insulating base material 11. Furthermore, the wiring pattern 12 has a pad part (not shown) for connecting to an electrode part (not shown) of the electronic component 14 shown in FIG. The cover layer 13 is formed so as to expose a region where the plurality of connection terminal portions 12A are formed and an electronic component mounting region (a region where the electronic component 14 is mounted in FIG. 1).

  In the present embodiment, an electronic component 14 is mounted in the electronic component mounting area of the first partial flexible substrate 10 as shown in FIG. In order to mount the electronic component 14, the electrodes (leads or bumps) of the electronic component 14 may be mounted on a pad portion (not shown) of the wiring pattern 12 via solder and processing such as solder reflow may be performed.

  As shown in FIGS. 1 to 3, the second partial flexible substrate 20 includes an insulating base material 21, a wiring pattern 22 formed on one surface of the insulating base material 21, and the wiring pattern 22. And a cover layer 23 that covers the surface of the insulating base material 21.

  The insulating base material 21 is formed of a liquid crystal polymer (LCP) having good moisture absorption dimensional stability. The wiring pattern 22 is formed by patterning a rolled copper foil having durability against repeated bending and bending operations. Further, the wiring pattern 22 has a connection terminal portion 22 </ b> A disposed at an end portion of the insulating base material 21. In the second partial flexible substrate 20, the same number of connection terminal portions 22 </ b> A as the connection terminal portions 12 </ b> A of the first partial flexible substrate 10 are formed at the same pitch.

  The first partial flexible substrate 10 and the second partial flexible substrate 20 having such a configuration are different in insulating base material, wiring material, and wiring rule between the wiring pattern 12 and the wiring pattern 22, and have a wiring function with each other. Is different. In the composite FPC 1 according to the present embodiment, the connection terminal portion 12A of the first partial flexible substrate 10 and the connection terminal portion 22A of the second partial flexible substrate 20 are joined by soldering, for example. In soldering, a solder plating layer may be formed on at least one surface of the connection terminal portion 12A and the connection terminal portion 22A. Further, in the present embodiment, the connection terminal portion 12A and the connection terminal portion 22A are soldered. However, the connection terminal portion 12A and the connection terminal portion 22A are joined using means such as joining using an anisotropic conductive adhesive film (ACF) or metal-to-metal bonding. May be.

  In the composite FPC 1 according to the present embodiment, since the electronic component 14 is mounted on the first partial flexible substrate 10, the insulating base material 11 made of polyimide having heat resistance against the reflow process is used. Further, the wiring pattern 12 of the first partial flexible substrate 10 is formed by patterning an electrolytic copper foil, and is a fine pattern in the vicinity of the mounting region. On the other hand, in the second partial flexible substrate 20, the constituent material of the insulating base material 21 is formed of a liquid crystal polymer having a high degree of flexibility. Moreover, the wiring pattern 22 uses the rolled copper foil which has durability with respect to bending | flexion operation | movement. In the composite FPC 1 having such a configuration, as shown in FIG. 3, the second partial flexible substrate 20 is bent with respect to the first partial flexible substrate 10.

  In the present embodiment, the pair of first partial flexible substrate 10 and second partial flexible substrate 20 having different wiring functions are assembled and joined so as to be conductive in a state of being assembled to the target structure. The first and second partial flexible substrates 10 and 20 having different wiring functions can be manufactured separately. For this reason, since the first and second partial flexible boards 10 and 20 having different wiring functions can be manufactured individually, the individual performances of the first and second partial flexible boards 10 and 20 can be improved. Further, by manufacturing according to the standards of the first and second partial flexible substrates 10 and 20, waste is reduced, the composite FPC 1 can be stably produced, and the yield can be improved.

  Further, in the present embodiment, since it has a flexible structure as a whole as a joined part of the partial flexible substrate having various functions, for example, it can be easily incorporated into an electronic device such as a mobile phone or a mobile terminal device, It is possible to improve assembly performance, save space, and improve the degree of freedom of installation.

(Second Embodiment)
FIG. 4 shows a composite FPC 30 according to the second embodiment of the present invention. In the composite FPC 30 according to the present embodiment, the first partial flexible substrate 40 is a substrate having a two-layer wiring pattern, whereas the second partial flexible substrate 50 is a substrate having a one-layer wiring pattern. FIG. 4 is a cross-sectional view showing a joint portion between the first partial flexible substrate 40 and the second partial flexible substrate 50 constituting the composite FPC 30.

  In the first partial flexible substrate 40, wiring patterns 43 and 44 are formed on both surfaces of an insulating base material (base layer) 41. On one surface of the end portion of the insulating base material 41, connection terminal portions 43 </ b> A of a plurality of wiring patterns 43 are arranged side by side. Also, cover layers 45 and 46 are provided on both surfaces where the wiring patterns 43 and 44 are formed. The cover layer 45 covering the wiring pattern 43 is formed so as to expose only the connection terminal portion 43A of the wiring pattern 43.

  The second partial flexible substrate 50 is generally composed of an insulating base 51, a wiring pattern 52 formed on one surface of the insulating base 51, and a cover layer 53. The wiring pattern 52 may have a connection terminal portion 52 </ b> A at the end of the insulating base 51.

  In the composite FPC 30 according to the present embodiment, the connection terminal portion 43A of the first partial flexible substrate 40 and the connection terminal portion 52A of the second partial flexible substrate 50 are joined, for example, by soldering. In the present embodiment, the connection terminal portion 43A and the connection terminal portion 52A are soldered. However, the connection terminal portion 43A and the connection terminal portion 52A are joined using means such as joining using an anisotropic conductive adhesive film (ACF) or intermetallic bonding. May be.

  In the composite FPC 30 having such a configuration, the wiring density of the first partial flexible substrate 40 is high, and the wiring density of the second partial flexible substrate 50 is low. In such a composite FPC 30, by separately manufacturing the partial flexible boards having different numbers of wiring layers, the performance of the individual partial flexible boards can be improved, the manufacturing becomes easy, and the manufacturing cost can be reduced.

(Third embodiment)
FIG. 5 shows a composite FPC 60 according to the third embodiment of the present invention. FIG. 5 is a cross-sectional view showing a joint portion between the first partial flexible substrate 70 and the second partial flexible substrate 80 constituting the composite FPC 60.

  The composite FPC 60 according to the present embodiment is configured by bonding a first partial flexible substrate 70 and a second partial flexible substrate 80. The first partial flexible substrate 70 is a substrate having three wiring layers, and the second partial flexible substrate 80 is a substrate having two wiring layers.

  The first partial flexible substrate 70 is bonded to each other, and wiring patterns 74 and 75 are formed on the outer surfaces of the insulating base materials 72 and 73 on which the wiring pattern 71 is formed at the interface, respectively. Cover layers 76 and 77 are provided on the outer surfaces of the insulating base materials 72 and 73. The wiring pattern 74 serves as a connection terminal portion 74 </ b> A at the end of the insulating base material 72. Therefore, the cover layer 76 is formed so as to expose the connection terminal portion 72A.

  The second partial flexible substrate 80 is a substrate having two wiring layers, and wiring patterns 82 and 83 are formed on both surfaces of the insulating base 81, respectively. Also, cover layers 84 and 85 are formed on both surfaces of the insulating base material 81. The wiring pattern 83 is a connection terminal portion 83 </ b> A at the end portion of the insulating base material 81. The cover layer 85 is formed so as to expose the connection terminal portion 83A.

  In the composite FPC 60 according to the present embodiment, the connection terminal portion 74A of the first partial flexible substrate 70 and the connection terminal portion 83A of the second partial flexible substrate 80 are joined by soldering, for example. In the present embodiment, the connection terminal portion 74A and the connection terminal portion 83A are soldered. However, the connection terminal portion 74A and the connection terminal portion 83A are bonded using a method such as bonding using an anisotropic conductive adhesive film (ACF) or metal-to-metal bonding. May be.

  In the composite FPC 60 having such a configuration, the number of wiring layers of the first partial flexible substrate 70 is three, and the number of wiring layers of the second partial flexible substrate 80 is different from two layers. By manufacturing the partial flexible substrates 70 and 80 separately, the performance of each partial flexible substrate can be enhanced, the manufacturing becomes easy, and the manufacturing cost can be reduced.

(Fourth embodiment)
FIG. 6 shows a composite FPC 90 according to the fourth embodiment of the present invention. The composite FPC 90 of the present embodiment is constructed by assembling the first to sixth partial flexible boards 100, 110, 120, 130, 140, and 150 as shown in FIG. Has been.

  In the present embodiment, the insulating bases of the first partial flexible substrate 100, the fifth partial flexible substrate 140, and the sixth partial flexible substrate 150 are formed of polyimide having a low degree of flexibility. Further, the insulating base material of the second partial flexible substrate 110, the third partial flexible substrate 120, and the fourth partial flexible substrate 130 has good moisture absorption dimensional stability and has durability against bending. It is made of polymer. The first partial flexible substrate 100, the second partial flexible substrate 110, the fifth partial flexible substrate 140, and the sixth partial flexible substrate 150 are formed in a substantially rectangular shape. The second partial flexible substrate 110 has a strip-shaped cable portion 111 that is joined to the first partial flexible substrate 100 and bent in accordance with the operation.

  An electronic component 160 is mounted on the first partial flexible substrate 100, and an electronic component 170 is mounted on the second partial flexible substrate 110. The third partial flexible substrate 120 and the fourth partial flexible substrate 130 are formed in a substantially L shape.

  The composite FPC 90 according to the present embodiment can be joined using means such as soldering, joining using an anisotropic conductive adhesive film (ACF), or intermetallic bonding between the partial flexible boards.

  In the composite FPC 90 having such a configuration, the first partial flexible substrate 100 and the second partial flexible substrate 110 on which the electronic components 160 and 170 are mounted are formed in a relatively fine pattern, and the degree of flexibility is relatively high. Is small. Here, when a fine pattern is formed, for example, a copper foil having a thickness of 9 μm can be used. On the other hand, the third partial flexible substrate 120 and the fourth partial flexible substrate 130 are formed in a relatively rough pattern. Here, when the rough pattern is formed, a copper foil having a thickness of, for example, about 18 μm can be used. Thus, although the wiring rule is different between the partial flexible boards, each partial flexible board is manufactured separately, so that the manufacturing becomes easy and the manufacturing cost can be reduced.

  In addition, the composite FPC 90 according to the present embodiment has a complicated shape, but each partial flexible substrate has a simple structure. In the complex FPC 90 having such a complicated structure, each partial flexible substrate can be easily manufactured separately, so that the yield of the partial flexible substrate is good. Therefore, the composite FPC 90 configured by combining these partial flexible substrates can also be manufactured with high yield.

  Further, in the composite FPC 90 of the present embodiment, since the shape of each partial flexible substrate is a simple shape (substantially rectangular shape), the number of sheets taken per sheet, which is the base plate of the insulating base material, is high and wasteful. The manufacturing cost can be reduced.

(Other embodiments)
It should not be understood that the descriptions and drawings which form part of the disclosure of the above-described embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above embodiment, the materials constituting the insulating base of the partial flexible substrate to be joined to each other are different from each other, and the function as a wiring board is different even when the thickness of the insulating base is different. Application is effective.

  Further, the wiring pattern includes the case where the conductor metal is different in addition to the type (rolled copper foil, electrolytic copper foil, etc.) and thickness of the copper foil used.

  Furthermore, in the said embodiment, although demonstrated as the example of the combination of 2 layers and 1 layer, and the combination of 3 layers and 2 layers as the number of layers of a wiring pattern, it is not limited to these.

It is a perspective view which shows the principal part of the composite FPC which concerns on the 1st Embodiment of this invention. It is sectional drawing of the junction part of the composite FPC which concerns on the 1st Embodiment of this invention. It is sectional drawing of the junction part of the composite FPC which concerns on the 1st Embodiment of this invention, and shows the state which bent one partial flexible substrate. It is sectional drawing of the junction part of the composite FPC which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the junction part of the composite FPC which concerns on the 3rd Embodiment of this invention. It is a top view of compound FPC concerning a 4th embodiment of the present invention.

Explanation of symbols

1, 30, 60, 90 Composite FPC (Composite Flexible Printed Circuit Board)
10, 40, 70, 100 1st partial flexible substrate 11, 21, 41, 51, 72, 73, 81 Insulating base material 12, 22, 43, 52, 71, 74, 75, 82, 83 Wiring pattern 12A, 22A, 43A, 52A, 72A, 74A, 83A Connection terminal portion 13, 23, 45, 46, 53, 76, 77, 84, 85 Cover layer 14, 160, 170 Electronic component 20, 50, 80, 110 Second part Flexible substrate 111 Cable portion 120 Third partial flexible substrate 130 Fourth partial flexible substrate 140 Fifth partial flexible substrate 150 Sixth partial flexible substrate

Claims (8)

  A composite flexible printed wiring board, wherein a plurality of partial flexible boards having different wiring functions are joined so as to be conductive in a state assembled to a target structure.   2. The composite flexible printed wiring board according to claim 1, wherein the plurality of partial flexible boards include different constituent materials of an insulating base material.   The composite flexible printed wiring board according to claim 1, wherein the plurality of partial flexible boards include ones having different wiring rules.   The composite flexible printed wiring board according to any one of claims 1 to 3, wherein the plurality of partial flexible boards include ones having different numbers of wiring layers.   The composite flexible printed wiring board according to any one of claims 1 to 4, wherein the plurality of partial flexible boards include ones having different degrees of flexibility.   The composite flexible printed wiring board according to any one of claims 1 to 5, wherein the plurality of partial flexible boards include ones having different manufacturing difficulty levels.   The composite flexible printed circuit board according to any one of claims 1 to 6, wherein the plurality of partial flexible boards include different constituent materials of a surface covering layer.   The composite flexible printed wiring board according to any one of claims 1 to 7, wherein the plurality of partial flexible boards include ones having different shapes.

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