JP6795732B2 - Flexible printed wiring board, manufacturing method of flexible printed wiring board and electronic components - Google Patents

Description

The present invention relates to a flexible printed wiring board, a method for manufacturing a flexible printed wiring board, and an electronic member, and more particularly to a flexible printed wiring board having a shield film that shields electromagnetic waves, a method for manufacturing a flexible printed wiring board, and an electronic member.

A flexible printed wiring board (FPC) is a printed wiring board in which a signal circuit or the like is formed on a flexible insulating film. For this reason, the flexible printed wiring board can be bent, and with the recent improvement in performance and miniaturization of OA equipment, communication equipment, mobile phones, etc., electronic devices are inside the housing having a narrow and complicated structure. It is often used to incorporate circuits. In recent years, with the high-density mounting of electronic components due to downsizing of electronic devices and the increase in signal frequency due to the increase in the amount of communication information, countermeasures against unnecessary radiation noise generated from flexible printed wiring boards have become increasingly important. ing.

The shield film is attached so as to be sandwiched from the upper surface and the lower surface of the flexible printed wiring board to reduce the radiation noise leaking from the flexible printed wiring board.

Japanese Unexamined Patent Publication No. 2000-269632 JP-A-2003-234022

Patent Document 1 discloses a conventional flexible printed wiring board. As shown in FIG. 10, in the flexible printed wiring board 1001 of the conventional example, a signal circuit 1003 and a ground circuit 1004 are provided on the insulating layer 1002. Insulating layers 1005 and 1006 are provided so as to cover the signal circuit 1003 and the ground circuit 1004. Further, it has a laminated structure in which a shield film 1009 including a conductive layer 1007 and an insulating coating layer 1008 is attached to the upper surface of 1006 and the lower surface of the insulating layer 1002, respectively. The conductive layer 1007 in the shield film 1009 is connected to the ground circuit 1004 via vias 1011 in through holes 1010 formed in the insulating layers 1005 and 1006.

In the method of attaching the electromagnetic wave shield film 1009 as shown in FIG. 10, radiation noise 1012 leaks from both end faces of the flexible printed wiring board 1001 especially when a high frequency signal is passed. Since the radiation noise 1012 leaked to the outside adversely affects peripheral devices, there is an increasing need to three-dimensionally shield the signal circuit 1003.

Patent Document 2 discloses a flexible flat cable covered with an electromagnetic wave absorber. As shown in FIG. 11, the flexible flat cable 1021 used in a digital camera has both upper and lower surfaces covered with an electromagnetic wave absorber 1022 in the form of a thin sheet of an electrical insulator composed of magnetic metal powder and rubber. There is. The electromagnetic wave absorber 1022 is bonded from above and below using an extremely thin thermosetting adhesive 1023 to cover the flexible flat cable 1021. In Patent Document 2, the high-frequency electromagnetic noise directly radiated from the flexible flat cable 1021 is absorbed by the sheet-shaped electromagnetic wave absorbing material, and the high-frequency electromagnetic noise is thermally lost. However, the electromagnetic wave absorber 1022 may not sufficiently absorb high-frequency electromagnetic noise.

The present invention has been made to solve such a problem, and is a flexible printed wiring board capable of suppressing radiation noise even when a high frequency signal is passed, a method for manufacturing the flexible printed wiring board, and an electronic member. I will provide a.

The flexible printed wiring board according to the present invention is a shield film in which a laminated wiring board extending in one direction and a conductive shield layer are formed on one side of an insulating insulating coating layer, and is an upper surface of the laminated wiring board. The lower surface is covered with the shield layer side, and at least a part of both end faces of the laminated wiring board in the plane parallel to the upper surface in the other direction orthogonal to the one direction is covered with the shield layer side. A shield film is provided, and the laminated wiring board is provided on the first conductive layer, the first insulating layer provided on the first conductive layer, and the first insulating layer, and extends in the one direction. The shield layer includes a signal circuit having a portion, a first insulating layer, a second insulating layer provided on the signal circuit, and a second conductive layer provided on the second insulating layer. Is connected to the second conductive layer.

In the method for manufacturing a flexible printed wiring board according to the present invention, a first conductive layer, a first insulating layer provided on the first conductive layer, and a first insulating layer provided on the first insulating layer and extending in one direction. A laminated wiring board including a signal circuit having a portion, the first insulating layer, a second insulating layer provided on the signal circuit, and a second conductive layer provided on the second insulating layer is prepared. A step of preparing a shield film having a conductive shield layer formed on one side of an insulating insulating coating layer, and a step of covering the lower surface of the laminated wiring board with the shield layer side of the shield film. The upper surface of the laminated wiring board is covered with the shield layer side of the shield film, and at least a part of both end faces of the laminated wiring board in a plane parallel to the upper surface in the other direction orthogonal to the upper surface is described. A step of covering the shield film on the shield layer side and a step of pressing the laminated wiring board and the shield film covering the laminated wiring board in the vertical direction are provided.

The electronic member according to the present invention is the one to which the flexible printed wiring board is connected.

According to the present invention, it is possible to provide a flexible printed wiring board, a method for manufacturing a flexible printed wiring board, and an electronic member capable of suppressing radiation noise even when a high frequency signal is passed.

It is sectional drawing which illustrates the flexible printed wiring board which concerns on Embodiment 1. FIG. It is a flowchart which illustrates the manufacturing method of the flexible printed wiring board which concerns on Embodiment 1. It is sectional drawing which illustrates the flexible printed wiring board which concerns on a comparative example. It is sectional drawing which illustrates the main part of the flexible printed wiring board which concerns on Embodiment 1. FIG. It is sectional drawing which illustrates the flexible printed wiring board which concerns on Embodiment 2. It is sectional drawing which illustrates the flexible printed wiring board which concerns on Embodiment 3. It is sectional drawing which illustrates the flexible printed wiring board which concerns on the modification 1 of Embodiment 3. It is sectional drawing which illustrates the flexible printed wiring board which concerns on modification 2 of Embodiment 3. It is sectional drawing which illustrates the flexible printed wiring board which concerns on the modification 3 of Embodiment 3. It is sectional drawing which illustrates the flexible printed wiring board. It is a perspective view exemplifying a flexible flat cable covered with an electromagnetic wave absorber. It is sectional drawing which illustrates the flexible printed wiring board which concerns on the modification of Embodiment 1. It is a figure which illustrated the kind of a shield film. It is a figure which illustrated the structure and the measurement result of Examples 1-10. It is a graph exemplifying the measurement results of Examples 1 to 10, the horizontal axis shows the Example, and the vertical axis shows the shielding effect.

(Embodiment 1)
The flexible printed wiring board according to the first embodiment will be described. First, the configuration of the flexible printed wiring board will be described. FIG. 1 is a cross-sectional view illustrating the flexible printed wiring board according to the first embodiment. As shown in FIG. 1, the flexible printed wiring board 1 includes a laminated wiring board 100, a shield film portion 201, a shield film portion 202, a cover layer 301, and a cover layer 302. The flexible printed wiring board 1 has flexibility because it includes a film-like member, a thin member, a flexible member, and the like. The flexible printed wiring board 1 extends in one direction in a flat state.

Here, for convenience of explanation of the flexible printed wiring board 1, an XYZ Cartesian coordinate system is introduced. With the flexible printed wiring board 1 flattened, the direction in which the flexible printed wiring board 1 extends is defined as the X-axis direction. The direction orthogonal to the upper surface of the flexible printed wiring board 1 is defined as the Z-axis direction. Therefore, the thickness direction of the flexible printed wiring board 1 is the Z-axis direction. Both end faces of the flexible printed wiring board 1 face in the Y-axis direction.

The laminated wiring board 100 extends in one direction, that is, in the X-axis direction. The laminated wiring board 100 is, for example, a flexible wiring board. The laminated wiring board 100 includes a conductive layer 11, a conductive layer 12, an insulating layer 21, an insulating layer 22, an insulating layer 23, a signal circuit 30, and a ground circuit 40. The laminated wiring board 100 is laminated in the order of the conductive layer 11, the insulating layer 21, the insulating layer 22, the insulating layer 23, and the conductive layer 12 from the bottom. A signal circuit 30 and a ground circuit 40 are provided between the insulating layer 21 and the insulating layer 22. In the laminated wiring board 100, another conductive layer or an insulating layer may be inserted between the layers. Both end faces face each other in the other direction orthogonal to one direction in the plane parallel to the upper surface 102 of the laminated wiring board 100, that is, in the Y-axis direction.

The conductive layer 11 is formed, for example, over the lower surface 101 of the laminated wiring board 100. The insulating layer 21 is provided on the conductive layer 11. The signal circuit 30 is provided on the insulating layer 21. The signal circuit 30 has a portion extending in the X-axis direction on the insulating layer 21. A plurality of signal circuits 30 may be provided. The signal circuit 30 may include, for example, a signal circuit 31 and a signal circuit 32. For example, the signal circuit 31 is arranged on the −Y axis direction side of the signal circuit 32.

The ground circuit 40 is provided on the insulating layer 21. The ground circuit 40 has a portion extending in the X-axis direction on the insulating layer 21. The ground circuit 40 is provided at a distance from the signal circuit 30. The ground circuit 40 has a portion extending in the X-axis direction along the signal circuit 30. A plurality of ground circuits 40 may be provided. The ground circuit 40 may include, for example, a ground circuit 41 and a ground circuit 42. For example, the ground circuit 41 is arranged on the −Y axis direction side of the signal circuit 31. The ground circuit 42 is arranged on the + Y axis direction side of the signal circuit 32. The ground circuit 41 and the ground circuit 42 are provided so as to sandwich the signal circuits 31 and 32 from both the + Y axis direction side and the −Y axis direction side. Therefore, the signal circuit 30 is arranged between the ground circuit 41 and the ground circuit 42.

The insulating layer 22 is provided on the insulating layer 21, the signal circuit 30, and the ground circuit 40. The insulating layer 22 is provided on the insulating layer 21 so as to cover the signal circuit 30 and the ground circuit 40 from above. The insulating layer 23 is provided on the insulating layer 22. The conductive layer 12 is provided on the insulating layer 23.

The laminated wiring board 100 may be formed by using, for example, a double-sided flexible copper-clad laminate (hereinafter referred to as double-sided FCCL) and a single-sided flexible copper-clad laminate (hereinafter referred to as single-sided FCCL). The double-sided FCCL has copper foils formed on both sides of a film-like insulating base material layer. The single-sided FCCL has a copper foil formed on one side of a film-like insulating base material layer.

The copper foil on one side of the double-sided FCCL is used as the conductive layer 11, and the insulating base material layer is used as the insulating layer 21. The copper foil on the other side is patterned and used as the signal circuit 30 and the ground circuit 40. Further, the copper foil on one side of the one-sided FCCL is used as the conductive layer 12, and the insulating base material layer is used as the insulating layer 23. When double-sided FCCL and single-sided FCCL are used, the laminated wiring board 100 is formed as follows. That is, the signal circuit 30 and the ground circuit 40 are formed by patterning the other surface of the double-sided FCCL. Next, the insulating base material layer side of the single-sided FCCL is adhered to the patterned surface of the double-sided FCCL. As a result, the laminated wiring board 100 is formed. The insulating adhesive used for bonding is the insulating layer 22.

The insulating base layer of the double-sided and single-sided FCCL is preferably polyester, polycarbonate, polyimide, polyphenylene sulfide, or liquid crystal polymer, and more preferably liquid crystal polymer or polyimide. Among these, a liquid crystal polymer having a low relative permittivity and a low dielectric loss tangent is more preferable in consideration of the use of a flexible printed wiring board for transmitting a high frequency signal. By providing an insulating base material such as these, the flexible printed wiring board 1 can obtain high heat resistance.

The signal circuit 30 sends an electric signal to an electronic member connected via the flexible printed wiring board 1. The ground circuit 40 is set to a ground potential for grounding. The material used for the conductive layer 11, the conductive layer 12, the signal circuit 30, and the ground circuit 40 is not limited to copper foil as long as it is conductive. Further, the laminated wiring board 100 is not limited to the one formed by using the double-sided FCCL and the single-sided FCCL. For example, the conductive layer 11, the insulating layer 21, the signal circuit 30, the ground circuit 40, the insulating layer 22, the insulating layer 23, and the conductive layer 12 may be laminated in this order.

The thickness of the conductive layer 11, the conductive layer 12, the signal circuit 30, and the ground circuit 40 is, for example, 18 [μm]. The thickness of the insulating layer 21 and the insulating layer 23 is, for example, 50 [μm]. The thickness of the insulating layer 22 is, for example, 35 [μm]. The thickness of each layer included in the laminated wiring board 100 is not limited to the above-mentioned thickness as long as the laminated wiring board 100 is flexible, and may be about 1 to 200 [μm].

The insulating cover layer 301 is provided below the laminated wiring board 100. The insulating cover layer 302 is provided above the laminated wiring board 100. The cover layers 301 and 302 are insulating materials that cover the laminated wiring board 100 and protect it from the external environment. Since the conductive layers 11 and 12 are exposed over the lower surface 101 and the upper surface 102 of the laminated wiring board 100, the cover layers 301 and 302 cover the conductive layers 11 and 12. The cover layers 301 and 302 include, for example, a coverlay 61 and an insulating adhesive layer 62. The coverlay 61 contains, for example, a resin such as polyimide as a material. The insulating adhesive layer 62 is, for example, an insulating adhesive. The cover layers 301 and 302 are not limited to the configuration including the coverlay 61 and the insulating adhesive layer 62, but are thermosetting or ultraviolet curable solder resists, photosensitive coverlay films, and photosensitive suitable for fine processing. It may be a coverlay film or the like, or a thermosetting adhesive or the like. The thickness of the cover layers 301 and 302 is, for example, 10 to 100 [μm], preferably 60 [μm]. The thickness of the coverlay 61 is, for example, 25 [μm], and the thickness of the insulating adhesive layer 62 is, for example, 35 [μm].

In the cover layers 301 and 302, the insulating adhesive layer 62 side is adhered to the laminated wiring board 100. Through holes 63 are formed in the cover layers 301 and 302. The through hole 63 penetrates the coverlay 61 and the insulating adhesive layer 62. An earth via 64 is formed inside the through hole 63. Therefore, the earth via 64 penetrates the cover layers 301 and 302.

The shield film portions 201 and 202 include an insulating coating layer 52 having an insulating property and a shielding layer 51 having a conductive film. The shield film portions 201 and 202 have a shield layer 51 formed on one side of the insulating coating layer 52. The shield film portions 201 and 202 are collectively referred to as a shield film 200. Therefore, the shield film 200 includes a shield film portion 201 that covers the lower surface 101 of the laminated wiring board 100, and a shield film portion 202 that covers the upper surface 102. The shield film 200 shields the laminated wiring board 100.

The shield layer 51 is, for example, a cured conductive adhesive of the shield film 200. Therefore, the shield film 200 includes the shield layer 51 and the insulating coating layer 52 in the flexible printed wiring board 1, and is a conductive adhesive layer and an insulating coating layer as a single unit before becoming a member of the flexible printed wiring board 1. 52 and is included. The shield layer 51 of the shield film 200 is not limited to the one obtained by curing the conductive adhesive as long as it has conductivity.

Further, as shown in FIG. 12, the shield film 200 may include a metal layer 53 formed between the insulating coating layer 52 and the shield layer 51. That is, in the flexible printed wiring board 1, the shield film 200 is composed of a shield layer 51 in which the conductive adhesive is cured, an insulating coating layer 52, and a metal layer 53 between the two, and the flexible printed wiring board. As a single unit before becoming the member of No. 1, the conductive adhesive layer, the metal layer 53, and the insulating coating layer 52 may be laminated. The metal layer 53 is, for example, a copper foil.

Here, the conductive adhesive layer and the insulating coating layer 52 in the shield film 200 will be described.

<< Conductive Adhesive Layer >>
The conductive adhesive layer can be appropriately selected from an isotropic conductive adhesive layer or an anisotropic conductive adhesive layer. The isotropic conductive adhesive layer has conductivity in the vertical direction and the horizontal direction when the shield film 200 is placed horizontally. Further, the anisotropic conductive adhesive layer has conductivity only in the vertical direction when the shield film 200 is placed horizontally. The conductive adhesive layer may be either isotropically conductive or anisotropically conductive, and in the case of isotropic conductivity, the connection reliability with the earth via 64 is improved, which is preferable. It is also effective in reducing noise leakage from the end faces 103 and 104 of the flexible printed wiring board 1. The conductive adhesive layer can be formed using a conductive adhesive. As the conductive adhesive, conventionally known ones containing a thermosetting resin, a curing agent, and conductive fine particles can be arbitrarily used. The thermosetting resin, the curing agent, and the conductive fine particles will be described below.

<Thermosetting resin>
A thermosetting resin is a resin having a plurality of functional groups capable of reacting with a curing agent. Functional groups include, for example, hydroxyl groups, phenolic hydroxyl groups, methoxymethyl groups, carboxyl groups, amino groups, epoxy groups, oxetanyl groups, oxazoline groups, oxazine groups, aziridine groups, thiol groups, isocyanate groups, blocked isocyanate groups and blocked functional groups. Examples thereof include a carboxyl group and a silanol group. The thermosetting resin includes, for example, acrylic resin, maleic acid resin, polybutadiene resin, polyester resin, polyurethane resin, polyurethane urea resin, epoxy resin, oxetane resin, phenoxy resin, polyimide resin, polyamide resin, polyamideimide resin, and phenolic resin. Known resins such as resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins and fluororesins can be mentioned.

The thermosetting resin can be used alone or in combination of two or more. Among these, polyurethane resin, polyurethane urea resin, epoxy resin, phenoxy resin, polyimide resin, polyamide resin, and polyamide-imide resin are preferable from the viewpoint of flexibility. The acid value of the thermosetting resin is preferably 1 to 50 mgKOH / g, more preferably 3 to 30 mgKOH / g. The weight average molecular weight of the thermosetting resin is preferably 20000 to 100,000. The content of the thermosetting resin in the solid content of the conductive adhesive layer is preferably 5 to 99% by weight, more preferably 7 to 80% by weight, still more preferably 10 to 60% by weight.

<Hardener>
The curing agent has a plurality of functional groups capable of reacting with the functional groups of the thermosetting resin. Examples of the curing agent include known compounds such as epoxy compounds, acid anhydride group-containing compounds, isocyanate compounds, aziridine compounds, amine compounds, phenol compounds, and organic metal compounds. The curing agent can be used alone or in combination of two or more. The curing agent is preferably contained in an amount of 1 to 50 parts by weight, more preferably 3 to 30 parts by weight, still more preferably 3 to 20 parts by weight, based on 100 parts by weight of the thermosetting resin.

<Conductive fine particles>
The conductive fine particles have a function of imparting conductivity to the conductive adhesive layer. As the material, the conductive fine particles are preferably conductive metals such as gold, platinum, silver, copper and nickel and their alloys, and fine particles of the conductive polymer, and silver or copper is preferable from the viewpoint of price and conductivity. More preferred.

Further, composite fine particles having a coating layer covering the surface of the nuclei with a metal or resin as the nuclei instead of the fine particles of a single material are also preferable from the viewpoint of cost reduction. Here, the nucleolus is preferably selected from nickel, silica, copper and alloys thereof, and resins, which are inexpensive. The coating layer is preferably a conductive metal or a conductive polymer. Conductive metals include, for example, gold, platinum, silver, nickel, manganese, indium and the like, and alloys thereof. Examples of the conductive polymer include polyaniline and polyacetylene. Among these, silver or copper is preferable from the viewpoint of price and conductivity.

The shape of the conductive fine particles is not limited as long as the desired conductivity can be obtained. Specifically, for example, spherical, flake-shaped, leaf-shaped, dendritic-shaped, plate-shaped, needle-shaped, rod-shaped, and grape-shaped are preferable. Further, two kinds of conductive fine particles having different shapes may be mixed.
The conductive fine particles can be used alone or in combination of two or more.

The average particle size of the conductive fine particles is the average particle size of D50, and is preferably 2 μm or more, more preferably 5 μm or more, and further preferably 7 μm or more, from the viewpoint of sufficiently ensuring conductivity. On the other hand, from the viewpoint of achieving compatibility with the thinness of the conductive adhesive layer, it is preferably 30 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less. The D50 average particle size can be determined by a laser diffraction / scattering method particle size distribution measuring device or the like.

The content of the conductive fine particles in the solid content of the conductive adhesive layer is preferably 1 to 95% by weight, more preferably 20 to 93% by weight, still more preferably 40 to 90% by weight. It is preferable to mix 10 to 700 parts by weight with respect to 100 parts by weight, and more preferably 20 to 500 parts by weight. When the content is 20 to 500 parts by weight, the shield film 200 having better electromagnetic wave shielding property can be obtained.

Conductive adhesives include silane coupling agents, rust preventives, reducing agents, antioxidants, pigments, dyes, tackifier resins, plasticizers, UV absorbers, defoaming agents, leveling adjusters, etc. Fillers, flame retardants, etc. can be blended.

The conductive adhesive can be obtained by mixing and stirring the materials described above. For stirring, for example, a stirring device known for a dispermat, a homogenizer, or the like can be used.

A known method can be used for producing the conductive adhesive layer. For example, a method of forming a conductive layer by applying a conductive adhesive on a peelable sheet and drying it, or using an extrusion molding machine such as a T-die to extrude the conductive adhesive into a sheet. It can also be formed by.

The coating method is, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, dip coating method. A known coating method such as a method can be used. It is preferable to carry out a drying step at the time of coating. For the drying step, for example, a known drying device such as a hot air dryer or an infrared heater can be used.

The thickness of the conductive adhesive layer is preferably 2 to 100 μm, more preferably 4 to 50 μm, and even more preferably 6 to 30 μm. When the thickness is in the range of 2 to 100 μm, it becomes easy to balance the electromagnetic wave shielding property and the flexibility.

<< Insulation coating layer >>
The insulating coating layer can be formed by using a conventionally known insulating resin composition. The insulating resin composition may contain the thermosetting resin and the curing agent described in the conductive adhesive, if necessary. The thermosetting resin and the curing agent used for the insulating layer and the conductive adhesive layer may be the same or different. The insulating resin composition can be obtained in the same manner as the conductive adhesive. Further, as the insulating layer, a film formed of an insulating resin such as polyester, polycarbonate, polyimide, or polyphenylene sulfide can also be used. The thickness of the insulating layer is usually about 2 to 20 μm.

The shield film portion 201 covers the lower surface 101 of the laminated wiring board 100 with the shield layer 51 side. Therefore, the surface on the shield layer 51 side faces the lower surface 101 on the laminated wiring board 100 side. The shield film portion 201 covers the laminated wiring board 100 and is in contact with the cover layer 301. Therefore, the cover layer 301 is provided between the lower surface 101 of the laminated wiring board 100 and the shield film portion 201 that covers the lower surface 101. The shield film portion 201 covers the lower surface 101 of the laminated wiring board 100 with the shield layer 51 side, and covers at least a part of both end faces of the laminated wiring board 100 in the Y-axis direction with the shield layer 51 side. For example, the shield film portion 201 covers both end faces of the conductive layer 11, the insulating layer 21, and the insulating layer 22 of the laminated wiring board 100. Therefore, the shield film portion 201 comes into contact with both end faces of the conductive layer 11. Further, the shield film portion 201 covers both end faces of the cover layer 301.

The shield film portion 202 covers the upper surface 102 of the laminated wiring board 100 with the shield layer 51 side. Therefore, the surface on the shield layer 51 side faces the upper surface 102 on the laminated wiring board 100 side. The shield film portion 202 covers the laminated wiring board 100 and is in contact with the cover layer 302. Therefore, the cover layer 302 is provided between the upper surface 102 of the laminated wiring board 100 and the shield film portion 202 that covers the upper surface 102. The shield film portion 202 covers the upper surface 102 of the laminated wiring board 100 with the shield layer 51 side, and covers at least a part of both end faces of the laminated wiring board 100 in the Y-axis direction with the shield layer 51 side. For example, the shield film portion 202 covers both end faces of the conductive layer 12, the insulating layer 23, and the insulating layer 22 of the laminated wiring board 100. Therefore, the shield film portion 202 comes into contact with both end faces of the conductive layer 12. Further, the shield film portion 202 covers both end faces of the cover layer 302.

Both end faces of the laminated wiring board 100, that is, end faces 103 and 104 are covered with a shield layer 51 from the conductive layer 11 to the conductive layer 12. Both end faces of the laminated wiring board 100 are covered with the shield layer 51 of the shield film portion 201 and the shield film portion 202 over the entire surface.

The boundary where the shield film portions 201 and 202 cover both end faces of the laminated wiring board 100 in the Y-axis direction is not limited to both end faces of the insulating layer 22. For example, the shield film portion 201 covers both end faces of the cover layer 301 and the conductive layer 11, and the shield film portion 202 covers both ends of the cover layer 302, the conductive layer 12, the insulating layer 23, the insulating layer 22, and the insulating layer 21. The boundary between both end faces of the shield film portions 201 and 202, such as covering the faces, may be anywhere on both end faces.

The shield layer 51 of the shield film portions 201 and 202 may cover both end faces so as to extend in the X-axis direction along the signal circuit 30. Further, the shield layer 51 may cover the entire surface of both end surfaces along the signal circuit 30. The shield layer 51 of the shield film portions 201 and 202 may have portions extending from both end faces of the laminated wiring board 100 in the outer Y-axis direction. The shield layer 51 may have a portion extending in the −Y axis direction from the end surface 103 on the −Y axis direction side and a portion extending in the + Y axis direction from the end surface 104 on the + Y axis direction side.

The earth via 64 penetrating the cover layers 301 and 302 may contain the same material as the conductive material contained in the shield layer 51. For example, the earth via 64 may contain the same material as the conductive material contained in the shield layer 51 by filling the inside of the through hole 63 with a part of the shield layer 51. The shield layer 51 is connected to the conductive layer 11 and the conductive layer 12 via the earth via 64. The earth via 64 penetrating the cover layers 301 and 302 may be arranged directly above the ground circuit 40.

Next, a method of manufacturing the flexible printed wiring board 1 according to the first embodiment will be described. FIG. 2 is a flowchart illustrating a manufacturing method of the flexible printed wiring board 1 according to the first embodiment.

As shown in step S11 of FIG. 2, first, the laminated wiring board 100 is prepared. The laminated wiring plate 100 includes a conductive layer 11, an insulating layer 21 provided on the conductive layer 11, a signal circuit 30 provided on the insulating layer 21 and having a portion extending in the X-axis direction, an insulating layer 21 and the insulating layer 21. The insulating layers 22 and 23 provided on the signal circuit 30 and the conductive layer 12 provided on the insulating layer 23 are included.

Next, as shown in step S12, the shield film 200 is prepared. Specifically, the shield film portions 201 and 202 in which the conductive shield layer 51 is formed on one side of the insulating coating layer 52 are prepared. The order of step S11 and step S12 may be reversed or may be simultaneous.

Next, as shown in step S13, the laminated wiring board 100 is covered with the shield film 200. Specifically, the lower surface 101 of the laminated wiring board 100 is covered with the shield layer 51 side of the shield film portion 201 via the insulating cover layer 301, and the upper surface 102 of the laminated wiring board 100 is covered with the insulating cover layer. It is covered with the shield layer 51 side of the shield film portion 202 via 302. At the same time, at least a part of both end faces of the laminated wiring board 100 in the Y-axis direction is covered with the shield layer 51 side of the shield film portions 201 and 202. The cover layer 302 is provided with a through hole 63. Further, it is desirable that the cover layer 301 is also provided with the through hole 63.

Next, as shown in step S14, pressing is performed. For example, heat is applied and heat pressed. Specifically, the shield films 201 and 202 covering the laminated wiring board 100 and the laminated wiring board 100 are pressed in the vertical direction. For example, the heat press preferably has a temperature of about 150 to 190 [° C.], a pressure of about 1 to 3 [MPa], and a time of about 1 to 60 [min]. As a result, the laminated wiring board 100, the cover layers 301 and 302, and the shield film portions 201 and 202 are crimped. At this time, the through hole 63 is filled with a part of the shield layer 51. In this way, the flexible printed wiring board 1 can be manufactured.

Next, a comparative example will be described before explaining the effect of the present embodiment. Then, the effect of this embodiment will be described in comparison with the comparative example. FIG. 3 is a cross-sectional view illustrating the flexible printed wiring board 1110 according to the comparative example. As shown in FIG. 3, in the flexible printed wiring board 1110, both end faces of the laminated wiring board 100 are not covered with the shield film 200. Therefore, it is not possible to suppress leakage of radiation noise 1012 from both end faces of the laminated wiring board 100.

FIG. 4 is a cross-sectional view illustrating a main part of the flexible printed wiring board 1 according to the first embodiment. As shown in FIG. 4, the flexible printed wiring board 1 of the present embodiment includes not only the upper surface 102 and the lower surface 101 of the laminated wiring board 100, but also both end faces of the laminated wiring board 100, that is, the end faces 103 on the −Y axis direction side. And the end face 104 on the + Y axis direction side is covered with the shield layer 51. Therefore, leakage of radiated noise from both end faces of the laminated wiring board 100 can be suppressed.

Further, the signal circuit 30 through which the high frequency signal flows is arranged so as to be sandwiched between the ground circuits 40. As a result, the shielding property of radiated noise can be improved.

The conductive layer 11 and the shield layer 51 are arranged below the signal circuit 30, and the conductive layer 12 and the shield layer 51 are arranged above the signal circuit 30. Since it is doubly shielded in this way, the shielding property can be improved.

Below the signal circuit 30, the conductive layer 11 and the shield layer 51 are connected by an earth via 64. As a result, the conductive layer 11 and the shield layer 51 can be surely at the same potential. Further, above the signal circuit 30, the conductive layer 12 and the shield layer 51 are connected by an earth via 64. As a result, the conductive layer 12 and the shield layer 51 can be surely at the same potential. Therefore, the shielding property of radiated noise can be improved.

The earth via 64 penetrates to the conductive layers 11 and 12 and does not penetrate to the ground circuit 40. The earth via 64 is formed in the through hole 63 formed in the cover layers 301 and 302. Therefore, since the earth via 64 does not have to penetrate through the conductive layers 11 and 12, the manufacturing can be facilitated and the cost can be reduced. Further, when the conductive layer 11 and the conductive layer 12 are not formed from the conductive adhesive layer but are formed from a metal layer such as a copper foil of FCCL, they are formed from the conductive adhesive layer. Compared with, the shielding property can be improved. This also applies to the case where the metal layer 53 is arranged between the shield layer 51 and the insulating coating layer 52 in the shield film 200 as shown in FIG. That is, the metal layer 53 of the shield film 200 can improve the shielding property.

Further, the fact that the conductive layers 11 and 12 are metal layers brings about an effect that the transmission characteristics in a high frequency region are excellent in addition to the effect of shielding properties. As a result, it is possible to cope with high frequency signal and high speed data processing. By such merits, that is, high shielding property and excellent transmission characteristics, it is possible to protect the signal propagating through the flexible printed wiring board 1 (FPC) from external noise and signal deterioration during propagation. It can also be used in places where it could not be used in terms of performance in the past.

Further, since the shield layer 51 of the shield film 200 is formed of the conductive adhesive layer, the adhesion to the laminated wiring board 100 can be improved.

The earth via 64 is formed directly above or directly below the ground circuit 40. Therefore, the spatial potential between the conductive layer 11 and the conductive layer 12, the spatial potential between the conductive layer 11 and the shield layer 51, and the spatial potential between the conductive layer 12 and the shield layer 51 should be made equal. It is possible to improve the shielding property.

The shield layer 51 of the shield film portion 201 and the shield film portion 202 has portions extending from both end surfaces of the laminated wiring board 100 in the outer Y-axis direction. As a result, leakage of radiated noise from both end faces of the laminated wiring board 100 can be suppressed.

(Embodiment 2)
Next, the flexible printed wiring board according to the second embodiment will be described. FIG. 5 is a cross-sectional view illustrating the flexible printed wiring board according to the second embodiment. As shown in FIG. 5, the flexible printed wiring board 2 has a different configuration of the shield film 200 from the flexible printed wiring board 1. That is, the flexible printed wiring board 2 includes one shield film 203 instead of the shield film portions 201 and 202 of the first embodiment. Since the configurations of the laminated wiring board 100, the cover layer 301, and the cover layer 302 are the same as those in the first embodiment, the description thereof will be omitted.

In the flexible printed wiring board 2, the laminated wiring board 100 is covered with one shield film 203. The shield film 203 starts to cover, for example, from the central portion of the lower surface 101 of the laminated wiring board 100. The portion at the beginning of covering is called the starting point portion 203a. The shield film 203 covers the end face 103, the upper surface 102, and the end face 104 of the laminated wiring board 100 in this order from the start point portion 203a, and overlaps the start point portion 203a at the central portion of the lower surface 101 of the laminated wiring board 100. The portion that overlaps the start point portion 203a and is completely wound is referred to as the end point portion 203b.

In the central portion of the lower surface 101 of the laminated wiring board 100, the end point portion 203b overlaps with the start point portion 203a. Therefore, in the overlapped portion, the shield layer 51 of the end point portion 203b is overlapped on the insulation coating layer 52 of the start point portion 203a. As described above, in the flexible printed wiring board 2, the shield film 203 has a portion in which the insulating coating layer 52 is sandwiched between the shield layer 51 and the shield layer 51 by overlapping.

Further, the shield layer 51 of the shield film 203 has portions extending from both end faces in the Y-axis direction of the laminated wiring board 100 in the outer Y-axis direction. The shield layer 51 has a portion extending in the −Y axis direction from the end surface 103 on the −Y axis direction side and a portion extending in the + Y axis direction from the end surface 104 on the + Y axis direction side. For example, when the shield film 203 covering the laminated wiring board 100 and the laminated wiring board 100 is hot-pressed in the vertical direction, the shield layer 51 extends from both end faces in the Y-axis direction of the laminated wiring board 100 in the outer Y-axis direction. Can be done.

Next, a method of manufacturing the flexible printed wiring board 2 according to the second embodiment will be described. The manufacturing method of the flexible printed wiring board 2 of the present embodiment is different from the manufacturing method of the first embodiment in the step of preparing the shield film 200 and the step of covering the laminated wiring board 100 with the shield film 200.

In the second embodiment, in the step of preparing the shield film 200, one shield film 203 is prepared instead of preparing the shield film portions 201 and 202. The shield film 203 has a conductive shield layer 51 formed on one side of an insulating insulating coating layer 52.

Further, in the step of covering the laminated wiring board 100 with the shield film 203, the shield film 203 is applied from the lower surface 101 of the laminated wiring board 100 in the order of the end surface 103 on the −Y axis direction, the upper surface 102, and the end surface 104 on the + Y axis direction. , Cover the laminated wiring board 100 so as to wrap around it. Then, by stacking the shield film 203, the portion where the insulating coating layer 52 is sandwiched between the shield layer 51 and the shield layer 51 is provided. In this way, the flexible printed wiring board 2 can be manufactured.

According to the flexible printed wiring board 2 of the present embodiment, the shield film 203 covers the laminated wiring board 100 so as to wrap around it. Therefore, leakage of radiated noise can be suppressed. Further, in the joint portion of the shield film 203, the start point portion 203a and the end point portion 203b overlap each other. As a result, leakage of radiated noise from the joint portion can be suppressed. Other configurations and effects are included in the description of Embodiment 1.

(Embodiment 3)
Next, the flexible printed wiring board 3 according to the third embodiment will be described. FIG. 6 is a cross-sectional view illustrating the flexible printed wiring board according to the third embodiment.

As shown in FIG. 6, the flexible printed wiring board 3 includes a extending conductive layer 71 extending in the Y-axis direction from the conductive layer 11 and an extending insulating layer 72 extending in the Y-axis direction from the insulating layer 21. It further includes an extension 70. Therefore, the extending portion 70 is provided on the side in the −Y axis direction from the end surface 103 of the laminated wiring board 100 and on the + Y axis direction side from the end surface 104. The extending portion 70 extends outward in the Y-axis direction from both end faces of the insulating layer 22, the insulating layer 23, and the conductive layer 12. Further, when the conductive layer 11 and the insulating layer 21 are formed by using the double-sided FCCL, the extending portion 70 may include the conductive layer remaining by patterning the signal circuit 30 and the ground circuit 40 in the double-sided FCCL.

The plurality of connecting vias 74 penetrate the extending portion 70. The plurality of connecting vias 74 are arranged along the X-axis direction in the extending portion 70. The plurality of connecting vias 74 may contain the same material as that contained in the shield layer 51. Further, the plurality of connecting vias 74 may include a conductive material plated on the inner surface of the through hole 73 penetrating the extending portion 70.

The shield film 200 includes a shield film portion 201 that covers the lower surface 101 of the laminated wiring board 100, and a shield film portion 202 that covers the upper surface 102. The shield film portion 201 covers both end faces of the cover layer 301 in the Y-axis direction. Further, the shield film portion 201 covers the lower surface of the extending portion 70. The shield film portion 202 covers both end surfaces of the insulating layer 22, the insulating layer 23, the conductive layer 12, and the cover layer 302 in the Y-axis direction. Further, the shield film portion 202 covers the upper surface of the extending portion 70. Therefore, the shield layer 51 of the shield film portion 201 and the shield film portion 202 has portions extending from both end faces in the Y-axis direction of the laminated wiring board 100 in the outer Y-axis direction. Further, the shield film portion 202 is connected to the shield film portion 201 via a plurality of connecting vias 74 penetrating the extending portion 70.

Next, a method of manufacturing the flexible printed wiring board 3 according to the third embodiment will be described. The manufacturing method of the present embodiment is different from the manufacturing method of the first embodiment in the step of preparing the laminated wiring board 100, the step of covering the laminated wiring board 100 with the shield film 200, and the step of pressing.

In the manufacturing method of the third embodiment, in the step of preparing the laminated wiring board 100, the extending conductive layer 71 extending in the Y-axis direction from the conductive layer 11 and the extending insulating layer 72 extending in the Y-axis direction from the insulating layer 21. The extension portion 70 including the above is also prepared. A plurality of through holes 73 are formed in the extending portion 70. The inner surfaces of the plurality of through holes 73 may be plated with a conductive material. Further, the inside of the plurality of through holes 73 may be filled with the conductive paste.

In the step of covering the laminated wiring board 100 with the shield film 200, the lower surface 101 of the laminated wiring board 100 is covered with the shield layer 51 side of the shield film portion 201. At the same time, both end faces of the cover layer 301 in the Y-axis direction and the lower surface of the extending portion 70 are covered with the shield layer 51 side of the shield film portion 201. Further, the upper surface 102 of the laminated wiring board 100 is covered with the shield layer 51 side of the shield film portion 202. At the same time, both end faces of the insulating layer 22, the insulating layer 23, the conductive layer 12, and the cover layer 302 in the Y-axis direction, and the upper surface of the extending portion 70 are covered with the shield layer 51 side of the shield film portion 202.

In the pressing step, the through hole 73 is filled with a part of the shield layer 51. When the inner surfaces of the plurality of through holes 73 are plated with a conductive material, it is not necessary to fill the through holes 73 with a part of the shield layer 51.

According to the flexible printed wiring board 3 of the present embodiment, since the extending portion 70 is provided, handling can be facilitated. In addition, the shield film portions 201 and 202 can be easily attached. Other configurations and effects are included in the description of embodiments 1 and 2.

(Modification example)
Next, a modified example of the third embodiment will be described. FIG. 7 is a cross-sectional view illustrating the flexible printed wiring board according to the first modification of the third embodiment, and FIG. 8 is a sectional view illustrating the flexible printed wiring board according to the second modification of the third embodiment. FIG. 9 is a cross-sectional view illustrating the flexible printed wiring board according to the third modification of the third embodiment.

As shown in FIG. 7, in the flexible printed wiring board 3a, the laminated wiring board 100a includes a conductive layer 11, an insulating layer 21a, an insulating layer 22a, and a conductive layer 12. A signal circuit 30 and a ground circuit are provided between the insulating layer 21a and the insulating layer 22a. The insulating layer 21a and the insulating layer 22a contain a liquid crystal polymer as a material.

The laminated wiring board 100a may be formed by using, for example, a double-sided FCCL and a single-sided FCCL. The insulating substrate layer of the double-sided FCCL and the single-sided FCCL contains a liquid crystal polymer as a material. The copper foil on one side of the double-sided FCCL is used as the conductive layer 11, and the insulating base material layer is used as the insulating layer 21a. The copper foil on the other side is patterned and used as the signal circuit 30 and the ground circuit 40. Further, the copper foil on one side of the one-sided FCCL is used as the conductive layer 12, and the insulating base material layer is used as the insulating layer 22a. When double-sided FCCL and single-sided FCCL are used, the laminated wiring board 100a is formed as follows. That is, the signal circuit 30 and the ground circuit 40 are formed by patterning the other surface of the double-sided FCCL. Next, the insulating base material layer side of the single-sided FCCL is adhered to the patterned surface of the double-sided FCCL. As a result, the laminated wiring board 100a is formed.

In the flexible printed wiring board 3a, the extending portion 70 includes the extending conductive layer 71 and the extending insulating layer 72a. The extending conductive layer 71 and the extending insulating layer 72a contain the same materials as the conductive layer 11 and the insulating layer 21a. When the conductive layer 11 and the insulating layer 21a are formed by using the double-sided FCCL, the extending portion 70 may include the conductive layer remaining by patterning the signal circuit 30 and the ground circuit 40 in the double-sided FCCL.

A resist layer 303 is formed on the lower surface 101 of the laminated wiring board 100a instead of the cover layer 301. Further, a resist layer 304 is formed on the upper surface 102 of the laminated wiring board 100a instead of the cover layer 302. A through hole 63 is formed in the resist layer 304. An earth via 64 is formed inside the through hole 63. The shield layer 51 in the shield film portions 201 and 202 covers the laminated wiring board 100a via the resist layers 303 and 304.

The resist layers 303 and 304 may be omitted as in the flexible printed wiring board 3b shown in FIG. In this case, the shield layer 51 in the shield film portions 201 and 202 directly covers the laminated wiring board 100a without passing through the cover layers 301 and 302 or the resist layers 303 and 304. Therefore, since the surfaces of the conductive layers 11 and 12 are covered with the shield layer 51 formed from the conductive adhesive layer, the adhesiveness can be improved. Further, since the conductive layers 11 and 12 are formed of a metal layer such as a copper foil of FCCL, the effect of shielding property and the effect of transmission characteristics can be improved as described above. Other configurations and effects are included in the description of Embodiments 1-3.

As in the flexible printed wiring board 3c shown in FIG. 9, the cover layers 301 and 302 of the flexible printed wiring board 1 according to the first embodiment may be omitted. That is, the flexible printed wiring board 3c is a laminated wiring board 100 extending in the X-axis direction and a shield film 200 in which a conductive shield layer 51 is formed on one side of an insulating insulating coating layer 52. A shield film 200 is provided which covers the upper surface 102 and the lower surface 101 of the plate 100 with the shield layer 51 side, and covers at least a part of both end surfaces of the laminated wiring board 100 in the Y-axis direction with the shield layer 51 side. .. Here, the laminated wiring plate 100 is insulated from the conductive layer 11, the insulating layer 21 provided on the conductive layer 11, and the signal circuit 30 provided on the insulating layer 21 and having a portion extending in the X-axis direction. It includes an insulating layer 22 provided on the layer 21 and the signal circuit 30, and a conductive layer 12 provided on the insulating layer 22. The shield layer 51 is connected to the conductive layer 11 and the conductive layer 12.

Even in such a configuration, since the surfaces of the conductive layers 11 and 12 are covered with the shield layer 51 formed from the conductive adhesive layer, the adhesiveness can be improved. Further, since the conductive layers 11 and 12 are formed of a metal layer such as a copper foil of FCCL, the shielding property can be improved. Other configurations and effects are included in the description of Embodiments 1-3.

<Example>
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. First, a method for preparing a measurement sample will be described.

[Measurement sample preparation]
(Example 1)
The laminated wiring board 100 is manufactured by using double-sided FCCL and single-sided FCCL. The double-sided FCCL is obtained by laminating a rolled copper foil having a thickness of 12 [μm] on both sides of a polyimide film having a thickness of 50 [μm]. Signal circuits 31 and 32 and ground circuits 41 and 42 are formed on one of the rolled copper foils in the double-sided FCCL. The lengths of the signal circuits 31 and 32 and the ground circuits 41 and 42 in the X-axis direction are, for example, 10 [cm]. The ground circuits 41 and 42 are formed on the outside of both sides of the signal circuits 31 and 32 in parallel with the signal circuits 31 and 32. The appearance and tolerance inspection specifications of the circuit shall be the JPCA standard (JPCA-DG02). The other rolled copper foil in the double-sided FCCL becomes the conductive layer 11. The polyimide film in the double-sided FCCL becomes the insulating layer 21.

The single-sided FCCL is obtained by laminating a rolled copper foil having a thickness of 12 [μm] on one side of a polyimide film having a thickness of 12.5 [μm]. The rolled copper foil in the single-sided FCCL is the conductive layer 12. The polyimide film in the single-sided FCCL is the insulating layer 23.

Next, the polyimide film side of the single-sided FCCL and the circuit-forming surface side of the double-sided FCCL are laminated via an insulating adhesive. Then, the pressure is applied under the condition of 30 [min] at a temperature of 150 [° C.] and a pressure of 2.0 [MPa]. The insulating adhesive is an insulating layer 22 having a thickness of 35 [μm].

Then, a through hole having a diameter of 0.1 [mm] (not shown) is provided, and then the electroless plating treatment is performed, and then the electrolytic plating treatment is performed to obtain the conductive layers 11 and 12 and the ground circuits 41 and 42. Ensure continuity.

Further, cover layers 301 and 302 are attached to the outer surfaces of the conductive layers 11 and 12 so as to cover the conductive layers 11 and 12, and 30 [min] at a temperature of 150 [° C.] and a pressure of 2.0 [MPa]. ] Crimping under the conditions of. The cover layers 301 and 302 are composed of a polyimide film having a thickness of 12.5 [μm] and an insulating adhesive layer having a thickness of 15 [μm]. The cover layers 301 and 302 are provided with through holes 63. After that, the circuit forming surface exposed in the through hole 63 and the conductive layers 11 and 12 are nickel-plated (not shown), and then gold-plated (not shown). Then, the ground circuit 41 is cut at a position of 300 [μm] on the −Y axis direction side, and the ground circuit 42 is cut at a position of 300 [μm] on the + Y axis direction side. As a result, the laminated wiring board 100 is formed.

Next, two shield films 200 shown in FIG. 13 are prepared for type A, and 150 with each shield layer 51 inside so as to cover both end faces 103 and 104 in the Y-axis direction of the laminated wiring board 100. Crimping is performed under the condition of 30 [min] at a temperature of [° C.] and a pressure of 2.0 [MPa]. Then, the shield film 200 is cut at positions of 1000 [μm] from both end faces of the laminated wiring board 100 in the + Y-axis direction and the −Y-axis direction side. As a result, the portions of the shield film 200 where only the shield film 200 overlaps are provided with a width of 1000 [μm] at both ends in the Y-axis direction. In this way, the flexible printed wiring board 1 is obtained.

As shown in FIG. 13, in the type A shield film 200, the thickness of the insulating coating layer 52 is 15 [μm], and the thickness of the shield layer 51 made of the insulating adhesive layer is 7 [. μm]. The conductive filler ratio of the insulating adhesive layer is 80 [wt%]. The type A shield film 200 does not include the metal layer 53. On the other hand, in the type B shield film 200, the thickness of the insulating coating layer 52 is 15 [μm], and the shield layer 51 includes an insulating adhesive layer and a metal layer 53. The thickness of the insulating adhesive layer is 7 [μm]. The conductive filler ratio of the insulating adhesive layer is 80 [wt%]. The thickness of the metal layer 53 is 3 [μm]. The metal layer 53 contains, for example, an electrolytic copper foil.

(Examples 2 to 9, Comparative Examples 1 and 2)
FIG. 14 is a diagram illustrating the configuration and measurement results of Examples 1 to 10. As shown in FIG. 14, except that the configuration of the flexible wiring board (FPC) of the first embodiment, the type of the shield film, and the width of the overlapped portion of the shield film only determined by the cutting position after the shield film 200 is attached are changed. Obtains flexible printed wiring boards of Examples 2 to 9 and Comparative Examples 1 and 2 by preparing a sample in the same manner as in Example 1.

In the second embodiment, the cutting position of the shield film 200 in the Y-axis direction is different from that of the first embodiment, and the shield film 200 is cut at 5000 [μm] from both end faces of the laminated wiring board 100. Therefore, the feature of the second embodiment is that the width of the overlapped portion of the shield film 200 extending from both end faces of the laminated wiring board 100 is 5000 [μm]. Other configurations are the same as in the first embodiment.

In the third embodiment, the cutting position of the shield film 200 in the Y-axis direction is different from that of the first embodiment, and the shield film 200 is cut at 200 [μm] from both end faces of the laminated wiring board 100. Therefore, the feature of Example 3 is that the width of the overlapping portion of the shield film 200 extending from both end faces of the laminated wiring board 100 is 200 [μm]. Other configurations are the same as in the first embodiment.

In the fourth embodiment, the cutting position of the shield film 200 in the Y-axis direction is different from that of the first embodiment, and the shield film 200 is cut at 100 [μm] from both end faces of the laminated wiring board 100. Therefore, the feature of the fourth embodiment is that the width of the overlapping portion of the shield film 200 extending from both end faces of the laminated wiring board 100 is 100 [μm]. Other configurations are the same as in the first embodiment.

In the fifth embodiment, the type of the shield film 200 is different from that of the first embodiment, and the type B shield film 200 is used. Therefore, the feature of Example 5 is that the type B shield film 200 is used. Other configurations are the same as in the first embodiment.

The sixth embodiment is different from the first embodiment in that the laminated wiring board 100 is provided with the extending portion 70 as shown in FIG. Therefore, the feature of Example 6 is the extending portion 70 shown in FIG. Other configurations are the same as in the first embodiment.

Example 7 is different from Example 6 in that the insulating layer 21a and the insulating layer 22a contain a liquid crystal polymer as a material, as shown in FIG. Further, it is different in that the resist layers 303 and 304 are used instead of the cover layers 301 and 302. Therefore, the features of Example 7 are the insulating layer 21a and the insulating layer 22a shown in FIG. 7, and the resist layers 303 and 304. Other configurations are the same as in the sixth embodiment.

Example 8 is different from Example 7 in that the resist layers 303 and 304 are omitted as shown in FIG. Therefore, the feature of Example 8 is the configuration of FIG. Other configurations are the same as in the seventh embodiment.

The ninth embodiment is different from the first embodiment in that the cover layers 301 and 302 of the flexible wiring board 1 are omitted as shown in FIG. Therefore, the feature of Example 9 is the configuration of FIG. Other configurations are the same as in the first embodiment.

In Comparative Example 1, the width of the overlapping portion of only the shield film covering the flexible printed wiring board 1001 shown in FIG. 10 is 0 [μm], that is, the cross section of the shield film and the laminated wiring board in the Y-axis direction is the same.

Comparative Example 2 is the case of the flexible printed wiring board shown in FIG. 3, and is not covered with the shield film.

(Example 10)
One shield film 203 is covered so as to wrap around the laminated wiring board 100, and the start point portion 203a and the end point portion 203b of the shield film 203 overlap each other. When the shield film 203 and the laminated wiring board 100 are hot-pressed in the vertical direction, the width of the portion where only the shield film 203 overlaps the both end surfaces of the laminated wiring board 100 is set to 1000 [μm].

The tenth embodiment is characterized by having a start point portion 203a and an end point portion 203b as shown in FIG. 5 with respect to the first embodiment. Other configurations are the same as in the first embodiment.

[Radiation noise evaluation]
A signal in the range of 1 MHz to 20 GHz is sent to the obtained flexible printed wiring board using a network analyzer, and radiation noise via a near magnetic field probe is measured. The probe position at the time of measurement is the position where the X-axis direction is +20 [mm] from the connection point with the high-frequency measuring instrument on the flexible printed wiring board, the Y-axis direction is the cross-sectional portion obtained by cutting the shield film, and the Z-axis. The direction is +100 [μm] from the top of the flexible printed wiring board. In Examples 1 to 10 and Comparative Examples 1 and 2, the width of the signal circuits 31 and 32 is 70 [μm], the distance between the signal circuits 31 and 32 is 100 [μm], and the ground circuits 41 and 42 are separated from each other. The width is 100 [μm], and the distance between the ground circuit 41 and the signal circuit 31 is 400 [μm].

Shields how much the output signal from the high frequency measuring instrument to the flexible printed wiring board and the input signal emitted from the flexible printed wiring board and input to the high frequency measuring instrument via the near magnetic field probe are attenuated. Measured as effect [dB]. The larger the attenuation, that is, the shielding effect [dB], the more the radiation noise can be shielded. Therefore, the larger the shielding effect [dB], the better the shielding property, and the closer it is to 0 [dB], the more radiated noise, and the flexible printed wiring board having poor shielding property. The radiation noise is measured in a frequency range of 300 kHz to 20 GHz in an atmosphere having a temperature of 25 ° C. and a relative humidity of 50%.

As shown in FIG. 14, in Example 1, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 93 [dB], 84 [dB] and 78 [dB], respectively. In Example 2, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 93 [dB], 84 [dB] and 78 [dB], respectively. In Example 3, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 93 [dB], 84 [dB] and 78 [dB], respectively.

In Example 4, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 88 [dB], 81 [dB] and 76 [dB], respectively. In Example 5, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 96 [dB], 89 [dB] and 87 [dB], respectively. In Example 6, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 84 [dB], 77 [dB] and 73 [dB], respectively.

In Example 7, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 83 [dB], 77 [dB] and 73 [dB], respectively. In Example 8, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 83 [dB], 77 [dB] and 73 [dB], respectively. In Example 9, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 83 [dB], 77 [dB] and 73 [dB], respectively.

In Example 10, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 94 [dB], 85 [dB] and 78 [dB], respectively. In Comparative Example 1, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 73 [dB], 69 [dB] and 66 [dB], respectively. In Comparative Example 2, the shielding effects at 1 [GHz], 2 [Ghz] and 3 [GHz] are 73 [dB], 70 [dB] and 76 [dB], respectively.

FIG. 15 is a graph illustrating the measurement results of Examples 1 to 10, where the horizontal axis shows the examples and the vertical axis shows the shielding effect. As shown in FIGS. 14 and 15, in Examples 1 to 10, radiation noise is reduced as compared with General Comparative Examples 1 and 2. Hereinafter, the viewpoint of the configuration of the FPC, the type of the shield film, and the width in which only the shield film overlaps will be described.

<FPC configuration>
As shown in FIGS. 14 and 15, the laminated wiring board 100 in the flexible wiring board has a greater shielding effect when it does not have the extending portion 70. However, even if the extending portion 70 is provided, the shielding effect is larger than that of the comparative example. Further, in the case of Example 10 wound with one shield film 203, the shielding effect is larger in the range of 1 to 2 [GHz] than in the case of using two shield sheets 200.

<Type of shield film>
As shown in Examples 1 and 5, the shielding effect when the type B shield film is used is larger than that when the type A shield film is used. Further, when the type B shield film is used, the shielding effect is large over the range of 1 to 3 [GHz].

<Width where only the shield film overlaps>
When the width of the overlapped portion of the shield film is 200 [μm] or more, the shielding effect is larger than that of 100 [μm]. When the width of the overlapped portion of the shield film is 200 to 1000 [μm], there is no significant difference in the shielding effect in the range of 1 to 3 [GHz].

[Handling property evaluation]
After cutting the obtained flexible printed wiring board to a length of about 30 mm to prepare a sample piece, 10 sample pieces are sealed in a container, a stroke of 40 [mm], a speed of 120 [times / min] with a shaker. ], The resistance of the flexible printed wiring board when shaken for 10 [min] is evaluated. Good (◎) indicates no scratches or damage, good (○) indicates no damage although scratches are seen, and 1 to 2 out of 10 are good (△). Shown.

As shown in FIG. 14, the flexible wiring boards of Examples 6 to 9 have excellent handleability. On the other hand, the flexible wiring board of the second embodiment has low handleability and is good. Other than that, it is good.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit. For example, the members constituting the flexible printed wiring boards of the first to third embodiments and the first and second modifications may be combined with each other.

Further, the flexible printed wiring boards of the first to third embodiments and the first and second modifications may be connected to the electronic member. The electronic member includes a member used for a communication device. The electronic member to which the flexible printed wiring boards of the first to third embodiments and the first and second embodiments are connected effectively suppresses high frequency noise radiated from the flexible printed wiring board, and at the same time shields high frequency noise from the outside. be able to. Further, in the communication device to which the flexible printed wiring boards of the first to third embodiments and the first and second modifications are connected, the influence of high frequency noise radiated from the flexible printed wiring boards is reduced.

The conductive layer 11 and the conductive layer 12 are also referred to as a first conductive layer and a second conductive layer. The insulating layer 21 is referred to as a first insulating layer, and any of the insulating layer 22 and the insulating layer 23 is also referred to as a second insulating layer. The cover layer 301 and the cover layer 302 are also referred to as a first cover layer and a second cover layer. The shield film portion 201 and the shield film portion 202 are also referred to as a first shield film portion and a second shield film portion.

1, 2, 3, 3a, 3b Flexible printed wiring board 11, 12 Conductive layer 21, 22, 23 Insulation layer 30, 31, 32 Signal circuit 40, 41, 42 Ground circuit 51 Shield layer 52 Insulation coating layer 53 Metal layer 61 Coverlay 62 Insulating Adhesive Layer 63 Through Hole 64 Earth Via 70 Extended Part 71 Extended Conductive Layer 72, 72a Extended Insulated Layer 73 Through Hole 74 Connection Via 100, 100a, 100b Laminated Wiring Board 101 Bottom 102 Top 103, 104 End face 200, 203 Shield film 201, 202 Shield film part 203a Start point part 203b End point part 301, 302 Cover layer 303, 304 Resist layer 1001 Flexible printed wiring board 1002 Insulation layer 1003 Signal circuit 1004 Ground circuit 1005, 1006 Insulation layer 1007 Conductive layer 1008 Insulation coating layer 1009 Shield film 1010 Through hole 1011 Via 1012 Radiation noise 1021 Flexible flat cable 1022 Electromagnetic wave absorber 1023 Thermocurable adhesive 1110 Flexible printed wiring board

Claims (9)

A laminated wiring board extending in one direction and
A shield film in which a conductive shield layer is formed on one side of an insulating insulating coating layer, the upper surface and the lower surface of the laminated wiring board are covered with the shield layer side, and the upper surface of the laminated wiring board. A shield film that covers at least a part of both end faces in the other direction orthogonal to the one direction in a plane parallel to the shield layer side.
With
The laminated wiring board is
With the first conductive layer
The first insulating layer provided on the first conductive layer and
A signal circuit provided on the first insulating layer and having a portion extending in one direction,
The first insulating layer and the second insulating layer provided on the signal circuit,
The second conductive layer provided on the second insulating layer and
Including
The shield layer is connected to the second conductive layer,
An extending portion including an extending conductive layer extending in the other direction from the first conductive layer and an extending insulating layer extending in the other direction from the first insulating layer is further provided.
The shield film is
The first shield film portion that covers the lower surface and
The second shield film portion that covers the upper surface and
Including
The shield layer of the first shield film portion and the second shield film portion has portions extending from both end faces in the other direction on the outside.
The second shield film portion is connected to the first shield film portion via a plurality of connecting vias penetrating the extending portion.
Flexible printed wiring board. The plurality of connecting vias contain the same material as that contained in the shield layer.
The flexible printed wiring board according to claim 1 . The plurality of connecting vias include a conductive material plated on the inner surface of the through hole penetrating the extending portion or a conductive material filled inside the through hole.
The flexible printed wiring board according to claim 1 . The laminated wiring board is
Further including a first ground circuit and a second ground circuit provided on the first insulating layer and having a portion extending in the one direction.
The second insulating layer is provided on the first ground circuit and the second ground circuit.
The signal circuit is arranged between the first ground circuit and the second ground circuit.
The flexible printed wiring board according to any one of claims 1 to 3 . The earth via penetrating the insulating second cover layer provided between the upper surface and the shield layer covering the upper surface is arranged directly above the second ground circuit.
The flexible printed wiring board according to claim 4 . The flexible printed wiring board according to any one of claims 1 to 5 , wherein the shield film includes a metal layer formed between the insulating coating layer and the shield layer. With the first conductive layer
The first insulating layer provided on the first conductive layer and
A signal circuit provided on the first insulating layer and having a portion extending in one direction,
The first insulating layer and the second insulating layer provided on the signal circuit,
The second conductive layer provided on the second insulating layer and
And the process of preparing a laminated wiring board including
The process of preparing a shield film in which a conductive shield layer is formed on one side of the insulating coating layer, and
The lower surface of the laminated wiring board is covered with the shield layer side of the shield film, the upper surface of the laminated wiring board is covered with the shield layer side of the shield film, and parallel to the upper surface of the laminated wiring board. A step of covering at least a part of both end faces in the other direction orthogonal to the one direction in the plane with the shield layer side of the shield film.
A step of pressing the laminated wiring board and the shield film covering the laminated wiring board in the vertical direction, and
With
The shield film is
The first shield film portion that covers the lower surface and
The second shield film portion that covers the upper surface and
Including
In the process of preparing the laminated wiring board,
An extending portion including the extending conductive layer extending in the other direction from the first conductive layer and the extending insulating layer extending in the other direction from the first insulating layer is also prepared.
In the step of covering with the shield layer side,
The lower surface and the lower surface of the extending portion are covered with the first shield film portion, and the upper surface and the upper surface of the extending portion are covered with the second shield film portion.
Manufacturing method of flexible printed wiring board. In the step of covering with the shield layer side,
The lower surface of the laminated wiring board is covered with the shield layer side of the shield film via an insulating first cover layer, and the upper surface of the laminated wiring board is covered with an insulating second cover having through holes. Cover with the shield layer side of the shield film via the layer,
In the pressing process
The through hole is filled with a part of the shield layer.
The method for manufacturing a flexible printed wiring board according to claim 7 . An electronic member to which the flexible printed wiring board according to any one of claims 1 to 6 is connected.

Images