JP2012009478A - Connection structure, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure in which a pair of flexible printed wiring boards having connection regions are electrically connected in the mutual connection regions through an anisotropic conductive material, and the surfaces of which can be made almost flush with each other, and an electronic apparatus including the connection structure.SOLUTION: In a connection structure 1, a pair of flexible printed wiring boards 10, 20 having connection regions G are electrically connected to each other through an anisotropic conductive material 30 in the connection regions G. Among regions where a pair of the flexible printed wiring boards 10, 20 overlap each other, the total thickness W1 of the region which do not correspond to the connection regions G is made almost equal to the total thickness W2 of the connection regions G, and these thicknesses are made almost equal to the total thickness W3 of the region where a pair of the flexible printed wiring boards 10, 20 do not overlap each other, separated from the region where a pair of the flexible printed wiring boards 10, 20 overlap each other at a boundary L between a pair of the flexible printed wiring boards 10, 20.

Description

  The present invention relates to a connection structure in which a pair of flexible printed wiring boards including electrode terminals are electrically connected via an anisotropic conductive material, and an electronic apparatus including the connection structure.

A semiconductor package is mounted by so-called flip chip bonding or the like on a mounting connection portion where an electrode terminal provided on a flexible printed wiring board (FPC) is exposed, or a plurality of flexible printed wiring boards are attached to each wiring board. In the field of electronics mounting, where the electrode terminals that are provided are electrically connected to each other through the exposed connection parts, the miniaturization and thinning of devices are increasingly accelerating, and even higher density mounting and higher connection reliability are achieved. A technology that can be realized is required.
One mounting method in electronics mounting is a method using an anisotropic conductive material (ACF) having thermal adhesiveness.
The anisotropic conductive material has a structure in which, for example, a powdery conductive component is dispersed in a binder (binder) such as a thermoplastic resin or a thermosetting resin.
Such an anisotropic conductive material is compressed in the thickness direction by heating and pressurization during thermocompression bonding, and as a result, the conductive components come close to or in contact with each other to form a conductive network. (Referred to as connection resistance).
However, at this time, the plane direction of the anisotropic conductive material maintains the initial state where the insulation resistance is high and the conductivity is low. Therefore, according to the anisotropic conductive material, a large number of electrode terminals arranged in the connection region by the connection resistance in the thickness direction while maintaining insulation between the adjacent electrode terminals by the insulation resistance in the plane direction and preventing a short circuit- The electrode terminals can be electrically connected at once and independently of each other.
At the same time, the FPC can be mechanically firmly fixed by thermocompression bonding, and the connection region of these members can be sealed with a binder, so that the mounting operation is easy.
As an example of a connection structure using such an anisotropic conductive material, there is Patent Document 1 below.

Japanese Patent Laid-Open No. 2005-210011

The above Patent Document 1 is an invention related to a printed wiring board and its connection method. FIG. 4 shows a connection structure in which a pair of printed wiring boards are electrically connected via an anisotropic conductive material as a conventional example. Yes.
In such a conventional connection structure using an anisotropic conductive material, a step is formed on the surface of a region where a pair of printed wiring boards overlap each other, so that the surface of the connection structure is substantially flush. What was not possible was common.
When such a step occurs (especially when the step is large), the connection structure is disposed inside an electronic device such as a mobile phone and is further electrically connected to other electronic components. During use, there is a possibility that the stepped part may be the starting point, causing damage to the electronic component or the like, or the connection with the anisotropic conductive material may be peeled off and the pair of printed wiring boards in the connected state may be peeled off was there. In particular, when the connection structure is disposed under the liquid crystal panel with the touch panel, there is a problem that when the touch panel is pressed, the stepped portion becomes a starting point and the liquid crystal panel is damaged.

  Therefore, the present invention solves the above-described problems in the prior art, and a pair of flexible printed wiring boards having an electrode terminal region in which electrode terminals are arranged are electrically connected to each other in the connection region via an anisotropic conductive material. An object of the present invention is to provide a connection structure in which the surface of the connection structure can be substantially flush with the connected connection structure, and an electronic device including the connection structure.

  The connection structure of the present invention is an electrical connection in which a pair of flexible printed wiring boards having a connection region in which electrode terminals are arranged are electrically connected to each other in the connection region via an anisotropic conductive material. The total thickness of the areas not corresponding to the connection area among the areas where the pair of flexible printed wiring boards overlap each other is substantially the same as the total thickness of the connection area, and The total thickness of the region where the pair of flexible printed wiring boards is separated from the region where the pair of flexible printed wiring boards overlap each other at the boundary between the pair of flexible printed wiring boards. The first characteristic is that the thickness is substantially the same as the thickness.

  According to the first aspect of the present invention, a pair of flexible printed wiring boards having a connection region in which electrode terminals are arranged are electrically connected to each other in the connection region via an anisotropic conductive material. The total thickness of a region that does not correspond to the connection region in the region where the pair of flexible printed wiring boards overlap with each other is substantially the same as the total thickness of the connection region. The pair of flexible printed wiring boards are separated from each other by an area where the pair of flexible printed wiring boards overlap each other at the boundary between the pair of flexible printed wiring boards. Since the total thickness of the non-overlapping regions is substantially the same, the surface of the connection structure can be made substantially flush. Therefore, it is possible to provide a connection structure that has good workability and can maintain electrical and mechanical connection reliability.

  In addition to the first feature of the present invention, the connection structure of the present invention is such that the flexible printed wiring board is formed by laminating at least an insulating substrate layer, a copper foil layer, and a coverlay layer. In the region where the pair of flexible printed wiring boards overlap each other, the region not corresponding to the connection region is at least one of the substrate layer, the copper foil layer, and the coverlay layer. The second feature is that the above is removed.

  According to the second feature of the present invention, in addition to the function and effect of the first feature of the present invention, the flexible printed wiring board includes at least an insulating substrate layer, a copper foil layer, and a coverlay layer. And in the region that does not correspond to the connection region among the regions in which the pair of flexible printed wiring boards overlap each other, among the substrate layer, the copper foil layer, and the coverlay layer Since at least one of the layers is removed, the total thickness of the regions that do not correspond to the connection region in the region where the pair of flexible printed wiring boards overlap with each other with a simple configuration is calculated as the total of the connection regions. The thickness can be substantially the same as the thickness.

  In the connection structure of the present invention, in addition to the first or second feature of the present invention, the pair of flexible printed wiring boards are bonded to each other with an adhesive layer in the vicinity of the connection region. This is the third feature.

According to the third feature of the present invention, in addition to the function and effect of the first or second feature of the present invention, the pair of flexible printed wiring boards is provided with an adhesive layer in the vicinity of the connection region. Therefore, the connection between the pair of flexible printed wiring boards by the anisotropic conductive material can be effectively reinforced. Therefore, a connection structure with high peel strength can be obtained.
Therefore, it is possible to provide a connection structure that is more workable and that can maintain electrical and mechanical connection reliability.

  According to a fourth aspect of the present invention, there is provided an electronic apparatus comprising the connection structure according to any one of claims 1 to 3.

  According to the fourth aspect of the present invention, since the electronic apparatus includes the connection structure according to any one of claims 1 to 3, the workability is good, and electrical and mechanical connection reliability is achieved. It can be set as the electronic device which can maintain. In addition, it is possible to provide an electronic device that has a simple configuration, good workability, and can maintain electrical and mechanical connection reliability.

According to the connection structure of the present invention, the surface of the connection structure can be made substantially flush. Therefore, it is possible to provide a connection structure that has good workability and can maintain electrical and mechanical connection reliability. In addition, it is possible to provide a connection structure that is easy to work with a simple configuration and that can maintain electrical and mechanical connection reliability.
Further, according to the electronic device of the present invention, it is possible to provide an electronic device that has good workability and can maintain electrical and mechanical connection reliability. In addition, it is possible to provide an electronic device that has a simple configuration and good assembling workability and can maintain electrical and mechanical connection reliability.

It is a figure which shows the connection structure which concerns on the 1st Embodiment of this invention, (a) is a whole perspective view of a connection structure, (b) is a disassembled perspective view of a connection structure. It is a top view which shows the principal part of the connection structure which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the connection structure which concerns on the 1st Embodiment of this invention, (a) shows the state before thermocompression bonding with a heating bar, (b) shows the state after thermocompression bonding with a heating bar. It is sectional drawing which shows the conventional connection structure, (a) shows the prior art example which is not provided with an opening part in a coverlay, (b) shows the prior art example which is provided with an opening part in a coverlay. It is sectional drawing which shows the connection structure which concerns on the 2nd Embodiment of this invention.

  Embodiments of a connection structure according to the present invention and an electronic device including the connection structure will be described with reference to the following drawings for understanding of the present invention. However, the following description is an embodiment of the present invention, and does not limit the contents described in the claims.

First, a connection structure according to a first embodiment of the present invention will be described with reference to FIGS.
The connection structure 1 according to the first embodiment of the present invention is a connection structure in which a pair of flexible printed wiring boards are electrically connected to each other by an anisotropic conductive material, and is disposed inside an electronic device (not shown). It is what is done.
As shown in FIG. 1, the connection structure 1 includes flexible printed wiring boards 10 and 20 and an anisotropic conductive material 30.

  In the present embodiment, the so-called pressure-receiving side flexible printed wiring board that receives the heat and pressure from the heating bar 40 shown in FIG. The so-called pressure-side flexible printed wiring board that applies the heat and pressure from is applied to the anisotropic conductive material 30 is the flexible printed wiring board 20.

The flexible printed wiring board 10 is a so-called single-sided flexible printed wiring board having a conductive layer on one side of a substrate.
As shown in FIG. 1B, the flexible printed wiring board 10 mainly includes a substrate 11, electrode terminals 12 a, conductor wirings 12 b, and a cover lay 13.
It should be noted that the electrode terminals 12a and the conductor wirings 12b having the same line width are actually shown in different thicknesses in FIGS. 1 and 2 for convenience of explanation.

The said board | substrate 11 comprises the board | substrate layer used as the base of the flexible printed wiring board 10, and is formed with the insulating resin film.
As a resin film, what consists of a resin material excellent in the softness | flexibility is used. For example, any resin film may be used as long as it is normally used as a resin film for forming a flexible printed wiring board such as a polyimide film or a polyester film.
In particular, those having high heat resistance in addition to flexibility are desirable. For example, polyamide resin films, polyimide resin films such as polyimide and polyamideimide, and polyethylene naphthalate can be preferably used.
The heat-resistant resin may be any resin as long as it is normally used as a heat-resistant resin for forming a flexible printed wiring board, such as a polyimide resin or an epoxy resin.

The electrode terminal 12a is an electrode terminal that is electrically connected to the electrode terminal 22a of the flexible printed wiring board 20 through the anisotropic conductive material 30, and the cover lay 13 is not laminated as shown in FIG. It is disposed on the substrate 11 in an exposed state.
Moreover, in this embodiment, the connection area | region G is formed by arrange | positioning several electrode terminal 12a, 22a in parallel in the area | region shown with a broken line in FIG.1 (b) and FIG. 2 in the flexible printed wiring boards 10 and 20, respectively. It is.
Here, the “connection region” refers to a region in which a plurality of parallel electrode terminals 12 a and 22 a are sealed by the anisotropic conductive material 30 and are electrically connected to each other.
The electrode terminal 12a is formed using a known forming method such as etching the conductive layer 12 shown in FIGS. 1 to 3 made of a conductive metal laminated on the surface of the substrate 11. In the present embodiment, the conductive layer 12 is formed of a copper foil layer.

Further, in the present embodiment, as indicated by a broken line in FIG. 3A, the connection region G corresponds to the region where the pair of flexible printed wiring boards 10 and 20 corresponding to the length A portion overlap each other. The conductive layer 12 of the length A1 portion, which is a region that is not to be etched, is removed by etching.
By adopting such a configuration, as shown in FIG. 3 (b), it corresponds to the connection region G in the region where the pair of flexible printed wiring boards 10 and 20 corresponding to the length A portion overlap each other. The total thickness W1 of the length A1 portion, which is a region that is not, can be made substantially the same as the total thickness W2 of the length A2 portion, which is a region corresponding to the connection region G.
Therefore, the surface of the region where the pair of flexible printed wiring boards overlap each other can be made substantially flush.
Further, as shown in FIG. 3 (b), the total thickness W1 and the total thickness W2 are set at a boundary L between the pair of flexible printed wiring boards 10 and 20, and a pair of flexible printed wiring boards corresponding to the length A portion. The total thickness W3 of the region where the pair of flexible printed wiring boards 10 and 20 corresponding to the length B portion is separated from the region where the layers 10 and 20 overlap each other is substantially the same.
By setting it as such a structure, the surface of the connection structure 1 can be made substantially flush.
Therefore, it is possible to provide a connection structure 1 that has good workability and can maintain electrical and mechanical connection reliability.
Here, “total thickness” refers to the distance between the outermost surfaces of the front side and the back side of the connection structure 1.
Further, “substantially the same thickness” indicates that the ratio of the total thickness W1 and the total thickness W2 to the total thickness W3 is within ± 25%.
Further, the “boundary L” means the tip S of the flexible printed wiring board 20 among the boundaries between the flexible printed wiring board 10 and the flexible printed wiring board 20 formed on the surface of the connection structure 1 shown in FIG. And the boundary formed between the flexible printed wiring board 10 and the flexible printed wiring board 10.

  That is, a conventional connection structure, for example, as shown in FIG. 4A, a connection including a flexible printed wiring board 10 that is disposed on the substrate 11 in an exposed state without the electrode terminals 12a being covered with the coverlay 13. In the structure 2 and the connection structure 3 including the flexible printed wiring board 10 in which the electrode terminals 12a are exposed in the opening K formed in the cover lay 13 as shown in FIG. In general, the surface of the region where the pair of flexible printed wiring boards 10 and 20 corresponding to the portion A overlap each other cannot be flattened.

More specifically, the total thickness W1 of the length A1 portion that is a region not corresponding to the connection region G and the total thickness W2 of the length A2 portion that is a region corresponding to the connection region G are substantially the same. In general, a step is formed on the surface of the region where the pair of flexible printed wiring boards 10 and 20 overlap each other, and the surface of the connection structure 1 cannot be made substantially flush. .
When such a step occurs, the connection structures 2 and 3 are disposed inside an electronic device such as a cellular phone (not shown) and are further electrically connected to other electronic components. In some cases, the stepped portion is the starting point, the electronic component or the like is damaged, the connection by the anisotropic conductive material 30 is peeled off, and the flexible printed wiring boards 10 and 20 are peeled off.
In particular, when the connection structures 2 and 3 are disposed under a liquid crystal panel with a touch panel, the stepped portion may be a starting point when the touch panel is pressed, and the liquid crystal panel may be damaged.
In the conventional connection structures 2 and 3, the same members and the same functions as those of the connection structure 1 are denoted by the same reference numerals.

Therefore, with the configuration of the present invention, it is possible to prevent a step from being formed on the surface of the region where the pair of flexible printed wiring boards 10 and 20 overlap each other, and the surface of the connection structure 1 is substantially flush. It is possible to prevent the electronic component from being damaged or the connection with the anisotropic conductive material 30 is peeled off and the flexible printed wiring boards 10 and 20 are peeled off when being assembled or used. .
In particular, when the connection structure 1 is disposed under a liquid crystal panel with a touch panel, it is possible to reliably prevent the liquid crystal panel from being damaged due to a stepped portion when the touch panel is pressed.
Therefore, it is possible to provide a connection structure 1 that has good workability and can maintain electrical and mechanical connection reliability.

The conductive metal may be any metal such as copper, silver, gold, etc. as long as it is normally used for forming an electrode terminal of a flexible printed wiring board.
The number of electrode terminals 12a, the arrangement position on the flexible printed wiring board 10, and the like can be changed as appropriate.

The conductor wiring 12 b forms a wiring pattern of the flexible printed wiring board 10.
The conductor wiring 12b is formed by using a known forming method such as etching the conductive layer 12 which is a copper foil layer laminated on the surface of the substrate 11, similarly to the electrode terminal 12a described above.
In addition, the number of conductor wirings 12b, an arrangement position, etc. can be changed suitably.

The coverlay 13 forms a coverlay layer that is an insulating layer covering the conductive layer 12.
As the coverlay 13, a polyimide film with an adhesive, a photosensitive resist, a liquid resist, or the like can be used.
As shown in FIG. 3, in the present embodiment, the cover lay 13 is laminated on the surface of the conductive layer 12 via a cover lay adhesive 13 a that is a cover lay adhesive layer.

  In the present embodiment, the flexible printed wiring board 20 on the pressure side has the same members and functions as those of the substrate 11, the electrode terminals 12 a, the conductor wiring 12 b, and the cover lay 13 that mainly constitute the flexible printed wiring board 10. Since this is a so-called single-sided flexible printed wiring board composed of the substrate 21, the electrode terminal 22a, the conductor wiring 22b, and the cover lay 23, the following detailed description will be omitted.

The anisotropic conductive material 30 contains a conductive component in a binder (binder), has conductivity in the thickness direction by heating and pressurization during thermocompression bonding, and is insulated in the surface direction. And has an adhesive property for bonding members together.
The binder may be any material as long as it is normally used as a binder for forming the anisotropic conductive material 30, such as a thermoplastic resin or a thermosetting resin.
The conductive component may be any material as long as it is normally used as a conductive component for forming the anisotropic conductive material 30, such as nickel.

Further, as shown in FIG. 2, the size of the anisotropic conductive material 30 is set such that the lateral length C is larger than the length between the electrode terminals 12a disposed at both ends of the plurality of parallel electrode terminals 12a. It is desirable that the length is slightly longer and the length D in the vertical direction is slightly shorter than the length in the vertical direction of the electrode terminal 12a. As a result, after thermocompression bonding with the heating bar 40, the region G surrounded by a substantially square indicated by a dotted line can be covered. In this embodiment, the anisotropic conductive material 30 is formed in a film shape. The configuration uses a conductive film.
Of course, the configuration is not limited to such a configuration, and an anisotropic conductive paste may be used as the anisotropic conductive material 30.

Next, a method for forming the connection structure 1 will be described with reference to FIG.
The flexible printed wiring board 10 is placed on a fixed table (not shown) using a positioning jig, and the electrode terminal 22a faces the electrode terminal 12a in a state where the anisotropic conductive material 30 is temporarily bonded. The flexible printed wiring board 20 is disposed on the substrate. And after positioning with the guide hole and alignment mark which are formed in the mutual flexible printed wiring boards 10 and 20 for positioning and which are not shown in figure, it is predetermined temperature and pressure from the upper part of the flexible printed wiring board 20 with the heating bar 40. The connection structure 1 is formed by heating and pressurizing with time.
Here, the “guide hole” is a through-hole formed by punching the flexible printed wiring boards 10 and 20 with each other in order to roughly position the flexible printed wiring boards 10 and 20. It is.
The “alignment mark” is a mark made of a conductive metal or the like formed between the flexible printed wiring boards 10 and 20 in order to accurately align the electrode terminals 12a and 22a.
Of course, the method of forming the connection structure 1 is not limited to that of this embodiment, and any method can be used as long as the flexible printed wiring boards 10 and 20 can be electrically connected via the anisotropic conductive material 30. May be.

  The connection structure 1 formed in this way is disposed inside an electronic device such as a mobile phone (not shown). With such a configuration, it is possible to provide an electronic device that has a simple configuration, good workability, and can maintain electrical and mechanical connection reliability.

Next, a connection structure according to the second embodiment of the present invention will be described with reference to FIG.
The connection structure 4 according to the second embodiment of the present invention is different from the connection structure 1 described above in the configuration of the pressure-receiving side flexible printed wiring board and between the pair of flexible printed wiring boards. The connection agent layer is interposed in the vicinity of the connection region.
Since other configurations are the same as the connection structure 1 according to the first embodiment of the present invention described above, the same members and the same functions are denoted by the same reference numerals, and the following description is given. Omitted.
Further, in FIG. 5, the pair of flexible printed wiring boards 10 and 20 constituting the connection structure 4 are illustrated in a separated state in order to suitably explain the structure of the connection structure according to the second embodiment of the present invention. In addition, in the flexible printed wiring board 10, a layer removed with a gap between layers is illustrated. (In the completed state of the connection structure 4, the gap generated between the layers indicated by the broken line is filled.)

As shown in FIG. 5, the connection structure 4 is configured so that the pressure-receiving side flexible printed wiring board 10 is a so-called double-sided flexible wiring board.
Further, as shown by a broken line in FIG. 5, in the length A1 portion, which is a region not corresponding to the connection region G, in a region where the pair of flexible printed wiring boards 10 and 20 corresponding to the length A portion overlap each other. The conductive layer 12 that is the copper foil layer on the front side surface and the back side surface of the flexible printed wiring board 10 is removed, and the coverlay adhesive 13a that is the coverlay adhesive layer on the back side surface of the flexible printed wiring board 10 and the cover The cover lay 13 which is a lay layer is removed.
In the length A2 portion, which is a region corresponding to the connection region G, the conductive layer 12 that is the copper foil layer on the back side surface of the flexible printed wiring board 10 is removed.
By adopting such a configuration, as shown in FIG. 5, among the regions where the pair of flexible printed wiring boards 10 and 20 corresponding to the length A portion overlap each other, the region does not correspond to the connection region G. The total thickness W1 of the length A1 portion can be made substantially the same as the total thickness W2 of the length A2 portion, which is a region corresponding to the connection region G, and the pair of flexible printed wiring boards 10 and 20 can be mutually connected. It is possible to prevent a step from being formed on the surface of the overlapping region.
Further, the total thickness W1 and the total thickness W2 are separated from the region where the pair of flexible printed wiring boards 10 and 20 corresponding to the length A portion overlap each other at the boundary L between the pair of flexible printed wiring boards 10 and 20. The total thickness W3 of the region where the pair of flexible printed wiring boards 10 and 20 corresponding to the length B portion do not overlap each other is set to be substantially the same.
By setting it as such a structure, the surface of the connection structure 4 can be made substantially flush.
Therefore, it is possible to provide a connection structure 4 that has good workability and can maintain electrical and mechanical connection reliability.

  Moreover, in length A2 part which is a part corresponding to the connection area | region G, it can be set as the structure which does not arrange | position the insulating layer 12 which is a copper foil layer on the back side surface of the electrode terminal 12a. Therefore, it is possible to prevent heat from escaping to the conductive layer 12 disposed on the back side surface of the electrode terminal 12a during thermocompression bonding by the heating bar 40. Therefore, since the thermocompression bonding can be performed efficiently, the operation time for thermocompression bonding can be shortened, and the connection structure 4 capable of reducing the cost can be obtained.

Furthermore, an adhesive layer 50 is formed in the vicinity of the connection region G between the pair of flexible printed wiring boards 10 and 20, thereby forming an adhesive layer 50, thereby forming the pair of flexible printed wiring boards 10 and 20. Are adhered to each other by the adhesive layer 50.
The adhesive layer 50 is formed by a double-sided tape using a thermosetting resin as an adhesive. In this way, the adhesive layer 50 can be formed with a simple configuration, and simultaneously with the thermocompression bonding of the anisotropic conductive material 30 by the heating bar 40, the flexible printed wiring board 10 by the adhesive layer 50, Adhesion between 20 can be performed.

More specifically, with reference to FIG. 2 showing the first embodiment, a thermosetting resin is bonded to a region R indicated by a two-dot chain line between a pair of flexible printed wiring boards 10 and 20. A double-sided tape is interposed.
By adopting such a configuration, the load applied to the connection region G can be reduced, and therefore the connection strength of the flexible printed wiring boards 10 and 20 by the anisotropic conductive material 30 can be effectively reinforced, and peeling A strong connection structure 4 can be obtained. Therefore, it is possible to provide a connection structure 4 that is much more workable and that can maintain electrical and mechanical connection reliability.

The size and shape of the adhesive layer 50 are such that the lateral length E is equal to or greater than the lateral length of the connection region G, and the longitudinal length F is the longitudinal length of the connection region G. It is desirable to have a size and shape that can cover the region R surrounded by a substantially quadrilateral indicated by a two-dot chain line in FIG.
Of course, the present invention is not limited to such a configuration, as long as the adhesive strength that can reinforce the connection between the pair of flexible printed wiring boards 10 and 20 by the anisotropic conductive material 30 can be provided. The size and shape of the adhesive layer 50 can be changed as appropriate.
Further, the distance H between the adhesive layer 50 and the connection region G shown in FIG. 2 is preferably about 0 to 5 mm.
In the present embodiment, the adhesive layer 50 is formed of a double-sided tape using a thermosetting resin as an adhesive, but the present invention is not necessarily limited to such a configuration and may be an adhesive member having an adhesive force. For example, any other adhesive tape, thermosetting adhesive, thermoplastic adhesive, or the like may be used, and the properties may be any film, paste, film, or the like.

  In the first embodiment, the pressure-receiving side and pressure-side flexible printed wiring board 1020 is a so-called single-sided flexible printed wiring board. In the second embodiment, the pressure-receiving side flexible printed wiring board 10 is a so-called double-sided flexible printed wiring board. Although it was set as the structure which was set as the wiring board and the flexible printed wiring board 20 by the side of a pressurization was what was called a single-sided flexible printed wiring board, it does not necessarily restrict to such a structure. For example, the pressure-receiving side and pressure-side flexible printed wiring boards 10 and 20 may both be so-called double-sided flexible printed wiring. The pressure-receiving side flexible printed wiring board 10 may be a so-called single-sided flexible printed wiring board, and the pressure-side flexible printed wiring board 20 may be a so-called double-sided flexible printed wiring board.

  The layers constituting the flexible printed wiring boards 10 and 20 are not limited to those of the present embodiment, and can be changed as appropriate. For example, a shield layer may be separately provided. By adopting such a configuration, it is possible to provide a connection structure that can further maintain electrical connection reliability.

  In the first and second embodiments, by removing one or more copper foil layers or the like only on the pressure-receiving side flexible printed wiring board 10 side, a pair of flexible printed wiring boards 10 and 20 overlap each other. Among them, the total thickness W1 of the region not corresponding to the connection region G is set to be substantially the same as the total thickness W2 of the region corresponding to the connection region G, and the thickness is set between the pair of flexible printed wiring boards 10 and 20. A configuration in which the pair of flexible printed wiring boards 10 and 20 are separated from a region where the pair of flexible printed wiring boards 10 and 20 overlap each other at the boundary L, and the total thickness of the regions where the pair of flexible printed wiring boards 10 and 20 do not overlap each other is approximately the same. However, it is not necessarily limited to such a configuration. That is, among the regions where the pair of flexible printed wiring boards 10 and 20 overlap each other, the total thickness W1 of the region not corresponding to the connection region G is set to be substantially the same as the total thickness W2 of the region corresponding to the connection region G, and The pair of flexible printed wiring boards 10 and 20 is separated from the area where the pair of flexible printed wiring boards 10 and 20 overlap each other at the boundary L between the pair of flexible printed wiring boards 10 and 20. If it can be made substantially the same thickness as the total thickness of the areas that do not overlap each other, it may be configured to remove one or more copper foil layers only on the flexible printed wiring board 20 side on the pressure side, It is good also as a structure which removes multiple layers combining the copper foil layer etc. which comprise the flexible printed wiring boards 10 and 20 of a pressure receiving side and a pressurization side.

  Further, the layer to be removed is not limited to that of the present embodiment, and any layer that removes one or more of the layers constituting the pressure-receiving side and / or pressure-side flexible printed wiring boards 10 and 20 can be used. It is good also as a structure which removes a layer. However, in the region where the pair of flexible printed wiring boards 10 and 20 overlap each other, in the region not corresponding to the connection region G, at least one of the substrate layer, the copper foil layer, and the coverlay layer is used. It is desirable to remove more than one layer.

Moreover, the thickness of each layer, such as a substrate layer, a conductive layer, a coverlay layer, and an adhesive layer, constituting the pressure-receiving side and pressure-side flexible printed wiring boards 10 and 20 can be changed as appropriate. However, when the connection structure is formed, the total thickness W1 of the region not corresponding to the connection region G in the region where the pair of flexible printed wiring boards 10 and 20 overlap each other is the total thickness of the region corresponding to the connection region G. The thickness can be substantially the same as W2, and the thickness is separated from a region where the pair of flexible printed wiring boards 10 and 20 overlap each other at the boundary L between the pair of flexible printed wiring boards 10 and 20. The pair of flexible printed wiring boards 10 and 20 need to have a thickness that can be substantially the same as the total thickness of a region where they do not overlap each other.
Preferably, the total thicknesses W1, W2, and W3 are about 0.15 mm.
Further, the size, shape and the like of the pressure-receiving side and pressure-side flexible printed wiring boards need not be limited to those of the present embodiment, and can be changed as appropriate.

  According to the present invention, in a connection structure in which a pair of flexible printed wiring boards having a connection region in which electrode terminals are arranged are electrically connected to each other in the connection region via an anisotropic conductive material, The surface of the structure can be substantially flush. Therefore, since the workability is good and a connection structure that can maintain electrical and mechanical connection reliability can be obtained, a pair of flexible printed wiring boards having a connection region in which electrode terminals are arranged are anisotropic. Industrial applicability is high in the field of electronic equipment having a connection structure that is electrically connected to each other in a connection region via a conductive material.

DESCRIPTION OF SYMBOLS 1 Connection structure 2 Connection structure 3 Connection structure 4 Connection structure 10 Flexible printed wiring board 11 Board | substrate 12 Conductive layer 12a Electrode terminal 12b Conductor wiring 13 Coverlay 13a Coverlay adhesive 20 Flexible printed wiring board 21 Board | substrate 22a Electrode terminal 22b Conductor wiring 23 Coverlay 23a Coverlay adhesive 30 Anisotropic conductive material 40 Heating bar 50 Adhesive layer A Length A1 Length A2 Length B Length C Length D Length E Length F Length G Connection area H Distance K Opening L Boundary R Region S Front end W1 Total thickness W2 Total thickness W3 Total thickness

Claims (4)

  A pair of flexible printed wiring boards having a connection region in which electrode terminals are arranged are connected to each other in the connection region via an anisotropic conductive material, and the pair of flexible printed wiring boards are connected to each other. Of the areas where the flexible printed wiring boards overlap each other, the total thickness of the areas not corresponding to the connection areas is set to be substantially the same as the total thickness of the connection areas, and the thicknesses are set to the pair of flexible printed wiring boards. The total thickness of the region where the pair of flexible printed wiring boards are separated from each other and the region where the pair of flexible printed wiring boards do not overlap with each other is set to be approximately the same as the pair of flexible printed wiring boards. Connection structure.   The flexible printed wiring board is formed by laminating at least an insulating substrate layer, a copper foil layer, and a cover lay layer, and the connection region among the regions where the pair of flexible printed wiring boards overlap each other. 2. The connection structure according to claim 1, wherein at least one of the substrate layer, the copper foil layer, and the coverlay layer is removed in a region that does not correspond to 1.   The connection structure according to claim 1, wherein the pair of flexible printed wiring boards are bonded to each other with an adhesive layer in the vicinity of the connection region.   An electronic apparatus comprising the connection structure according to claim 1.

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