JP6286273B2 - Shield film, shield printed wiring board, and method for manufacturing shield printed wiring board - Google Patents

Description

  The present invention relates to a shield film that shields a printed wiring board or the like used in a computer, a communication device, a printer, a mobile phone, a video camera, or the like, a shield printed wiring board using the shield film, and a shield printed wiring board Regarding the method.

  A flexible printed wiring board (hereinafter also referred to as “FPC”) is a printed circuit without using an adhesive or an adhesive on at least one surface of a flexible insulating film such as a polyimide film or a polyester film. And, if necessary, a flexible insulation in which an opening is formed on the upper surface of the printed circuit corresponding to a part for forming a terminal for mounting a circuit component or a terminal for connection to an external substrate. The surface protective layer is formed by a technique such as bonding the film with an adhesive, or forming an opening by a process such as application of photosensitive insulating resin, drying, exposure, development, heat treatment, etc. In electronic devices such as mobile phones, video cameras, and notebook computers that are rapidly becoming smaller and more functional, they are often used to incorporate circuits into complex mechanisms.Furthermore, taking advantage of its excellent flexibility, it is also used for connection between a movable part such as a printer head and a control part. In an electronic device in which FPC is frequently used, countermeasures against electromagnetic wave shielding are indispensable. Even in FPCs used in the apparatus, a shielded flexible printed wiring board (hereinafter referred to as “shielded FPC”) with countermeasures against electromagnetic wave shielding. Has come to be used.

  For example, in the shield FPC disclosed in Patent Document 1, a cover film (protective layer) is formed by coating a resin on one side of a separate film with a release agent, and a shield layer is formed on one side of the cover film (protective layer). Are bonded together to form a shield film, and a shield film is applied to at least one surface side of the FPC by applying heat and pressure using a conductive adhesive, and a ground circuit provided on the shield layer and the FPC Is disclosed. For example, Patent Document 1 discloses a shield printed wiring board obtained by electrically connecting the two through a conductive adhesive and then peeling off the separate film.

JP 2004-95566 A

  However, as described above, when a cover film (protective layer) coated with a release agent on one side of the separate film is used, the degree of adhesion (peel strength) of the separate film to the cover film (protective layer) is determined by the release agent. Therefore, it is difficult to control the degree of adhesion (peel strength). Therefore, when the separate film is peeled off from the cover film (protective layer), the cover film (protective layer) itself may be broken due to excessively large adhesive force, or the separate film may be covered during the manufacturing process due to excessively small adhesive force. The film (protective layer) sometimes peeled off.

  Therefore, the present invention appropriately controls the adhesion force of the separate film to the protective layer, and prevents a problem caused by bonding with an excessively large adhesive force or an excessively small adhesive force, a shield printed wiring board, and An object of the present invention is to provide a method for manufacturing a shield printed wiring board.

  The shield film of the present invention forms a protective layer by coating a resin via a release agent on the surface side of the separate film having the concavo-convex portion formed on the entire one surface thereof, A shield film having an electromagnetic wave shield layer, wherein the protective layer has a surface roughness (Ra) of 0.2 μm to 1.0 μm when the separate film is peeled from the protective layer. .

  In the state where the separate film is adhered to the protective layer via the release agent as in the above configuration, the surface roughness (which is formed by transferring the uneven portion on the surface of the separate film and the uneven portion on the surface of the separate film) Ra) is a protective layer when the shield film is immersed in the chemical solution in the subsequent step, due to the anchor effect by the irregularities on the surface of the protective layer of 0.2 μm to 1.0 μm. And the separation film can be increased to the extent that the separation film is prevented from peeling off from the protective layer. Further, in the process of applying the release agent to the separate film having the uneven portion, the release agent is naturally dispersed and arranged in a substantially uniform manner, and further, the protective layer resin is applied so that the uneven portion on the surface of the separate film is A protective layer having a surface roughness (Ra) of 0.2 μm to 1.0 μm formed by transfer. Thereby, when peeling a separate film from a protective layer, the adhesiveness of the separate film with respect to a protective layer can be suppressed to such an extent that the protective layer itself is not torn by excessively large adhesive force. Thus, since the adhesive force with respect to the protective layer of a separate film can be controlled moderately, the malfunction by adhering with an excessively large adhesive force or an excessively small adhesive force can be prevented.

  The shield film of the present invention may have a peel strength of the separate film with respect to the protective layer of 1 N / 50 mm to 20 N / 50 mm.

  According to said structure, the adhesive strength with respect to the protective layer of a separate film can be more optimized by making peeling strength with respect to the protective layer of a separate film into 1N / 50mm-20N / 50mm.

  Moreover, the peeling strength with respect to the said protective layer of the said separate film after mounting the said shielding film on a printed wiring board, and heating and pressurizing the shielding film of this invention is 1N / 50mm-10N / 50mm May be a feature.

  According to said structure, by putting the said shield film in a printed wiring board, and making the peeling strength with respect to the said protective layer of the said separate film after heating and pressurizing into 1N / 50mm-10N / 50mm, The adhesion force of the separate film to the protective layer can be further optimized.

  In the shield film of the present invention, the electromagnetic wave shield layer may include a conductive adhesive layer.

  According to said structure, the ground circuit of a printed wiring board and an electromagnetic wave shield layer can be electrically connected reliably.

  The shield film of the present invention may be characterized in that the electromagnetic wave shielding layer further includes a metal layer, and the conductive adhesive layer is composed of an anisotropic conductive adhesive layer.

  According to said structure, since there is little quantity of an electroconductive filler, it can be made the thing excellent in flexibility.

  The shield film of the present invention may be characterized in that the conductive adhesive layer is composed of an isotropic conductive adhesive.

  According to the above configuration, it is possible to provide a ground connection to a ground circuit or the like and to have an electromagnetic wave shielding effect only by providing a conductive adhesive layer.

  In addition, the present invention provides a separation film having a concavo-convex portion formed on at least one surface of a substrate including one or more printed circuits on one side, and a release agent on the surface side where the concavo-convex portion is formed. A shield printed wiring board provided with a shield film in which a protective layer is formed by coating a resin and further formed with an electromagnetic wave shield layer, and the surface roughness of the protective layer when the separate film is peeled off from the protective layer The thickness (Ra) is 0.2 μm to 1.0 μm.

  According to the above configuration, regarding the shield printed wiring board having the electromagnetic wave shielding layer and the protective layer on one side of the substrate, in the state where the separate film is adhered to the protective layer through the release agent, The separation film for the protective layer is formed by the anchor effect by the irregularities on the surface of the protective layer having a surface roughness (Ra) of 0.2 μm to 1.0 μm, which is formed by transferring the irregularities on the surface of the separation film. The degree of adhesion prevents the separation of the separation film from the protective layer without the chemical solution entering between the protective layer and the separation film when the shield film is immersed in a chemical solution such as plating in the subsequent process. Can be increased. Moreover, by providing the unevenness | corrugation part on the surface of a separate film and the unevenness | corrugation part on the surface of a separate film, and the unevenness | corrugation part of the surface of a separate film formed by transferring the unevenness | corrugation part of the surface of a separation film to 0.2 micrometer-1.0 micrometer. In addition, since the release agent is naturally dispersed in the process of applying the release agent to the separate film, the release agent can be dispersed and arranged substantially uniformly. Thereby, when peeling a separate film from a protective layer, the adhesiveness of the separate film with respect to a protective layer can be suppressed to such an extent that the protective layer itself is not torn by excessively large adhesive force. Thus, since the adhesive force with respect to the protective layer of a separate film can be controlled moderately, the malfunction by adhering with an excessively large adhesive force or an excessively small adhesive force can be prevented.

  In the shielded printed wiring board of the present invention, the substrate including the printed circuit may be a flexible printed wiring board.

  According to said structure, a shield printed wiring board can be made excellent in flexibility.

  The shield printed wiring board of the present invention may be characterized in that the substrate including the printed circuit is a TAB tape for a tape carrier package.

  According to the above configuration, it is possible to obtain a shield printed wiring board that is flexible and excellent in assemblability.

  Further, the present invention provides a shield film in which a release agent, a protective layer, and an electromagnetic wave shielding layer are laminated at least on a surface on the concave-convex shape side of a separate film whose one surface is made concave-convex by mat processing. Surface roughness (Ra) by placing on at least one surface of a substrate including a printed circuit, heating and pressing the shield film and the substrate in the laminating direction, and then peeling the separate film from the protective layer. Is a method for producing a shielded printed wiring board, wherein the protective layer has a thickness of 0.2 μm to 1.0 μm.

  According to the above method, in the state where the separate film is adhered to the protective layer via the release agent, the unevenness on the surface of the separate film and the unevenness on the surface of the separate film are transferred to form a surface roughness ( Ra) is 0.2 μm to 1.0 μm, and the anchor effect by the uneven portions on the surface of the protective layer causes the adhesion of the separate film to the protective layer, when the shield film is immersed in a chemical solution such as a plating solution in a later step. It can be increased to such an extent that the chemical solution does not enter between the protective layer and the separate film, and prevents the separate film from peeling from the protective layer. Moreover, by providing the unevenness | corrugation part on the surface of a separate film and the unevenness | corrugation part on the surface of a separate film, and the unevenness | corrugation part of the surface of a separate film formed by transferring the unevenness | corrugation part of the surface of a separation film to 0.2 micrometer-1.0 micrometer. In addition, since the release agent is naturally dispersed in the process of applying the release agent to the separate film, the release agent can be dispersed and arranged substantially uniformly. Thereby, when peeling a separate film from a protective layer, the adhesiveness of the separate film with respect to a protective layer can be suppressed to such an extent that the protective layer itself is not torn by excessively large adhesive force. Thus, since the adhesive force with respect to the protective layer of a separate film can be controlled moderately, the malfunction by adhering with an excessively large adhesive force or an excessively small adhesive force can be prevented.

It is explanatory drawing of the manufacturing method of the shield FPC of this Embodiment, (a) shows the state which has mounted the shield film on the base film, and has pressurized with heating with a press, (b) is a separate. The state which has peeled the film is shown, (c) shows the state after peeling of a separate film. It is a cross-sectional view of the shield film used when manufacturing a shield FPC, (a) is an electromagnetic wave shield layer formed of an adhesive layer and a metal layer, (b) is an electromagnetic wave shield layer only an adhesive layer It is formed with. It is a partial enlarged view of the shield film of the cross-sectional view of shield FPC. It is a cross-sectional view of shield FPC, (b), (c) is a cross-sectional view of shield FPC of double-sided shield. It is a cross-sectional view of the shield FPC when the protective layer constituting the shield film has a single layer structure. It is the table | surface which put together the result of the evaluation test which concerns on an Example and a comparative example. It is explanatory drawing of the test method of the evaluation test which concerns on an Example and a comparative example.

  Hereinafter, an example of an embodiment of a shielded FPC according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a method for manufacturing a shielded FPC according to the present embodiment, and FIG. 2 is a cross-sectional view of a shield film used when manufacturing the shielded FPC. FIG. 1 (a) is formed on a base film 2 and is covered with an insulating film 4 except for at least a part (non-insulating portion) 3c of the ground circuit 3b in the printed circuit 3 including the signal circuit 3a and the ground circuit 3b. A state in which the shield film 1 is placed on the base film 5 thus formed and heated by the press machine P (PA, PB) while being pressurized p is shown. FIG. 3 is a partially enlarged view of the shield film in the cross-sectional view of the shield FPC.

  Here, the base film 2 and the printed circuit 3 may be bonded together with an adhesive, or may be bonded in the same manner as a so-called adhesiveless copper-clad laminate that does not use an adhesive. The insulating film 4 may be formed by bonding a flexible insulating film using an adhesive, or by a series of techniques such as application of a photosensitive insulating resin, drying, exposure, development, and heat treatment. . Furthermore, the base film 5 includes a single-sided FPC having a printed circuit only on one side of the base film, a double-sided FPC having a printed circuit on both sides of the base film, and such an FPC (flexible printed wiring board). Multi-layer FPC with multiple layers, Flexboard (registered trademark) with multi-layer component mounting part and cable part, Flex-rigid board with rigid members constituting the multi-layer part, or TAB for tape carrier package A tape or the like can be employed as appropriate.

  Here, the shield film 1 shown in FIG. 2A is used. As shown in FIG. 2A, the shield film 1 includes a separate film 6a, a release layer 6b, and a shield film body 9. The shield film body 9 was formed by sequentially coating a hard layer 7a made of a resin excellent in wear resistance and blocking resistance and a soft layer 7b made of a resin excellent in cushioning properties on the release layer 6b. It has the protective layer 7 and the adhesive layer 8a provided on the surface opposite to the surface in contact with the release layer 6b of the protective layer 7 through the metal layer 8b. Here, the electromagnetic wave shielding layer 8 is formed by the adhesive layer 8a made of a conductive adhesive and the metal layer 8b. In this electromagnetic wave shielding layer 8, the adhesive 8a ′ softened by heating h flows into the insulation removing portion 4a as indicated by an arrow by the pressure p (see FIG. 1A).

  The protective layer 7 may not have a two-layer structure including the hard layer 7a and the soft layer 7b, and may have a single-layer structure as shown in FIG. When this single-layer structure is adopted, a thermosetting resin, a thermoplastic resin, an electron beam curable resin, or the like can be used as the resin constituting the protective layer 7.

  Further, as shown in FIG. 3, the surface of the separate film 6a on the protective layer 7 side is matted. Specifically, by spraying fine sand on one surface of the separate film 6a and attaching irregularities 61 (convex portions 61a, concave portions 61b) to the surface, the single surface of the separate film 6a is made uneven to increase the surface area. Yes. Examples of the mat treatment include a sand mat, an etching mat, a coating mat, a chemical mat, and a kneading mat.

  As shown in FIG. 3, the surface of the hard layer 7 a constituting the protective layer 7 on the side of the separate film 6 a has a plurality of concave and convex portions 71 formed on the entire surface. The concavo-convex portion 71 is composed of a combination of an adjacent concave portion 71b and convex portion 71a. The concavo-convex portion 71 formed on the hard layer 7a is coated with the hard layer 7a along the concavo-convex 61 formed by matting on one side of the separate film 6a after the release layer 6b is coated on one side of the separate film 6a. (See the enlarged view of FIG. 3). Further, the surface roughness (Ra) of the surface of the hard layer 7a on which the concavo-convex portion 71 is provided after the separation film is peeled off is preferably 0.2 μm to 1.0 μm, and more preferably 0.2 μm. ˜0.6 μm is preferred.

  Further, the hard layer 7a constituting the protective layer 7 has a frictional mass of 500 grams according to a friction test method using a Gakushin type friction tester specified in JIS L 0849, and the test piece is reciprocated 30 times per minute. When reciprocating horizontally at a speed of 120 mm, the soft layer 7b is formed of a resin having abrasion resistance that does not cause scratches even if it is reciprocated 1000 times. The soft layer 7b has a motion defined in JIS K 7244-4. It is made of a resin having a modulus of elasticity of 3 gigapascals or less measured at a frequency of 1 Hz, a measurement temperature range of −50 ° C. to 150 ° C., and a temperature increase rate of 5 ° C. Since it is necessary to peel the separate film 6a from the protective layer 7 in a later step, the hard layer 7a having excellent wear resistance plays a role as a protective layer after the separation of the separate film 6a, and wears the protective layer 7 To prevent. Further, since the hard layer 7a is excellent in blocking resistance, it adheres to other things such as a transporting jig or a transporting belt for mounting and transporting the wiring board in a process requiring heating such as a reflow process in the circuit component mounting process. There is nothing. The metal layer 8b provided on the soft layer 7b of the protective layer 7 is cracked / ruptured even when the protective layer 7 serving as the base is heated and pressurized by the excellent hardness of the hard layer 7a and the cushioning effect of the soft layer 7b. Does not cause destruction. Further, when the shield film 1 is placed on the base film 5 including the printed circuit 3 and heated and pressed by the press machine P (PA, PB), the hard layer 7a is applied by the cushioning effect of the soft layer 7b. Since the pressure is gently transmitted to the hard layer 7a, the hard layer 7a having high hardness is prevented from cracking. As the resin for the hard layer and the soft layer, a thermosetting resin, a thermoplastic resin, an electron beam curable resin, or the like can be used.

  Further, after the release layer 6b is coated on one side of the separate film 6a, the release layer 6b is naturally distributed in a substantially uniform manner, the hard layer 7a of the protective layer 7 is coated, and the separate film 6a Are transferred to the hard layer 7a to form the protective layer 7 having a surface roughness (Ra) of 0.2 μm to 1.0 μm (see an enlarged view of FIG. 3).

  Further, the release layer 6b is not particularly limited as long as it has releasability with respect to the protective layer 7. For example, the release layer 6b is coated with a silicon or non-silicon melamine release agent or an acrylic release agent. PET film etc. which were made can be used. The maximum value of the thickness of the release layer 6b is preferably thinner than the height of the unevenness formed by matting the surface of the separate film 6a (the thickness of the release layer 6b exceeds the height of the unevenness). And the unevenness is substantially eliminated and it becomes difficult to control the peel strength of the separate film 6a with respect to the protective layer 7). In addition, as a method of laminating the hard layer 7a and the soft layer 7b on one side of the separate film 6a, coating is preferable, but as a layer forming method other than coating, lamination, extrusion, dipping, or the like may be used.

  Moreover, the peeling strength with respect to the protective layer 7 (hard layer 7a) of the separate film 6a when the separate film 6a is peeled from the hard layer 7a of the protective layer 7 is 1 N / 50 mm to 20 N / in the state before heating h and pressure p. It should be 50 mm. Further, the peel strength with respect to the protective layer 7 (hard layer 7a) is preferably 1 N / 50 mm to 10 N / 50 mm after heating h and pressure p, and more preferably 1 N / 50 mm to 4 N / 50 mm. Is preferred.

  By changing the surface roughness due to the irregularities 61 (convex portions 61a, concave portions 61b) of the separate film 6a formed by the mat processing and the type / amount of the release agent in the manufacturing stage according to the purpose of use, the separate film 6a is obtained. The width of the adhesive strength (peel strength) to the protective layer 7 can be increased, and the control (adjustment) of the adhesive strength can be facilitated.

  Then, after the adhesive 8a ′ is sufficiently adhered to the non-insulating portion 3c and the insulating film 4 of the ground circuit 3b, the formed shield flexible printed wiring board 10 is removed from the press P as shown in FIG. When the separated film 6a of the shield film 1 is peeled off together with the release layer 6b, the shield FPC 10 ′ shown in FIG. 1C in which the uneven portion 71 is provided on the surface of the hard layer 7a is obtained.

  As shown in FIG. 2 (a), the shield film 1 is thicker than the shield film main body 9 by the amount of the separate film 6a. Therefore, the shield film 1 can be easily punched into a predetermined size and can be cut cleanly. Easy to align. In addition, the cushioning effect is increased by the separate film 6 at the time of heating and pressurization, and pressure transmission is performed gently, so that the adhesive 8a ′ can easily flow into the insulating removal portion 4a. Accordingly, since the adhesive 8a ′ is sufficiently adhered to the surface of the non-insulating portion 3c of the ground circuit 3b, the connection conductivity is improved. If the separate film 6a is peeled off together with the release layer 6b, a thin and flexible shield FPC 10 ′ can be easily obtained. In addition, the shield film 1 may be used for a rigid wiring board.

  Both the base film 2 and the insulating film 4 are made of engineering plastic. Examples thereof include resins such as polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, and polyphenylene sulfide (PPS). An inexpensive polyester film is preferable when heat resistance is not required, and a polyphenylene sulfide film is preferable when flame resistance is required, and a polyimide film is preferable when heat resistance is required.

  For the separate film 6a, the same engineering plastic as that for the base film 2, the insulating film 4, and the protective layer 7 is used. However, an inexpensive polyester film is preferable because it is removed in the manufacturing process. Further, as the release layer 6b, a silicon film can be formed and used by a known method.

  Adhesive layer 8a is a thermoplastic resin such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, acrylic, etc., phenolic, epoxy, urethane as adhesive resin. , Melamine-based and alkyd-based thermosetting resins. In addition, a conductive adhesive in which a conductive filler such as metal or carbon is mixed with these adhesive resins to provide conductivity can also be used. In this way, the ground circuit 3b and the metal layer 8b can be reliably electrically connected by using the conductive adhesive. Moreover, you may use the anisotropic conductive adhesive which reduced the quantity of the conductive filler as a conductive adhesive. As described above, when an anisotropic conductive adhesive is used as the conductive adhesive, the film becomes thinner than the isotropic conductive adhesive, and the amount of the conductive filler is small. Can do. Moreover, an isotropic conductive adhesive can also be used as a conductive adhesive. As described above, when an isotropic conductive adhesive is used as the conductive adhesive, the ground connection to the ground circuit 3b or the like can be achieved and the electromagnetic wave can be obtained only by providing a conductive adhesive layer with the isotropic conductive adhesive. A shield effect can be given. Further, when heat resistance is not particularly required, a polyester-based thermoplastic resin that is not restricted by storage conditions or the like is desirable. When heat resistance or better flexibility is required, the electromagnetic wave shielding layer 8 is provided. A highly reliable epoxy-based thermosetting resin after formation is desirable. In either case, it is needless to say that a resin having a small bleeding (resin flow) during heating and pressurization is desirable.

  Moreover, in the said embodiment, although the metal layer 8b and the adhesive bond layer 8a are used as the electromagnetic wave shielding layer 8, when an isotropic conductive adhesive is used as the adhesive bond layer 8a as mentioned above, a metal layer You may make the structure which excluded 8b.

  Examples of the conductive filler include silver-coated copper filler obtained by silver-plating carbon, silver, copper, nickel, solder, aluminum, and copper powder, and fillers obtained by metal-plating resin balls, glass beads, or the like. A mixture of Silver is expensive, copper lacks heat resistance reliability, aluminum lacks moisture resistance reliability, and solder is difficult to obtain sufficient conductivity. It is preferable to use a silver-coated copper filler or nickel having high reliability.

  The blending ratio of the conductive filler such as a metal filler to the adhesive resin depends on the shape of the filler and the like, but in the case of the silver-coated copper filler, 10 to 400 parts by weight with respect to 100 parts by weight of the adhesive resin. It is preferable that the amount be 20 to 150 parts by weight. If it exceeds 400 parts by weight, the adhesion to the ground circuit (copper foil) 3b is lowered, and the flexibility of the shield FPC 10 ′ is deteriorated. On the other hand, if the amount is less than 10 parts by weight, the conductivity is significantly lowered. Moreover, in the case of a nickel filler, it is preferable to set it as 40-400 weight part with respect to 100 weight part of adhesive resin, More preferably, it is good to set it as 100-350 weight part. If it exceeds 400 parts by weight, the adhesion to the ground circuit (copper foil) 3b is lowered, and the flexibility of the shield FPC 10 ′ is deteriorated. On the other hand, when the amount is less than 40 parts by weight, the conductivity is remarkably lowered. The shape of the conductive filler such as a metal filler may be any of a spherical shape, a needle shape, a fiber shape, a flake shape, and a dendritic shape.

  As described above, the thickness of the adhesive layer 8a is about 3 μm to 25 μm when conductive fillers such as metal fillers are mixed. Moreover, when not mixing a conductive filler, it is 1 micrometer-10 micrometers. For this reason, the electromagnetic wave shielding layer 8 can be made thin, and a thin shield FPC 10 'can be obtained.

  Examples of the metal material forming the metal layer 8b include aluminum, copper, silver, and gold. The metal material may be appropriately selected according to the required shielding properties. However, copper has a problem that it is easily oxidized when exposed to the atmosphere, and gold is expensive. Therefore, inexpensive aluminum or highly reliable silver is used. preferable. The film thickness is appropriately selected according to the required shielding properties and flexibility, but is generally preferably 0.01 to 1.0 μm. When the thickness is less than 0.01 μm, the shielding effect is insufficient. On the other hand, when the thickness exceeds 1.0 μm, the flexibility is deteriorated. As a method for forming the metal layer 8b, there are vacuum deposition, sputtering, CVD, MO (metal organic), plating, and the like. However, in consideration of mass productivity, vacuum deposition is desirable, and an inexpensive and stable metal thin film can be obtained. it can. The metal layer is not limited to a metal thin film, and a metal foil may be used.

  The shield film 1 ′ shown in FIG. 2 (b) is provided with an electromagnetic wave shield layer 8 ′ made of only an adhesive layer 8a formed of a conductive adhesive in which a conductive filler is mixed on one side of the protective layer 7 and shielded. It differs from the thing of Fig.2 (a) by the point used as film main body 9 '. Since the metal layer 8b has a higher electrical conductivity than the adhesive layer 8a, when the metal layer 8b is provided as shown in FIG. 2 (a), it is less necessary to use an isotropic conductive adhesive. Therefore, the electromagnetic wave shielding layer 8 can be made thin. The configuration of the electromagnetic wave shielding layer 8 is not limited to this, but a material having good conductivity and flexibility is preferable.

  FIG. 4 is a cross-sectional view of the shielded FPC obtained as described above. In the shielded FPC of the present invention, instead of the shield film main body 9 in FIG. 1 (c), an electromagnetic wave shielding layer 8 ′ is formed only with an adhesive layer 8a formed of a conductive adhesive as shown in FIG. 2 (b). Of course, the shield film main body 9 'is also included. Various materials and forming methods constituting the shield film main body 9 include various types as described above.

  Furthermore, it is not limited to a single-sided shield, but also includes a double-sided shield as shown in FIGS. 4 (b) and 4 (c). In the double-sided shielded FPC 10A of FIG. 4B, the base film 2 ′ is provided on the insulating film 4 and the base film 2 ′ side above and below the ground circuit 3b so that the adhesive layer 8a is connected to the ground circuit 3b. An insulation removal portion 4a and an insulation removal portion 2a ′ are provided, and are connected to the adhesive layer 8a in the non-insulation portion 3c on the upper and lower surfaces of the ground circuit 3b. Here, the base film 2 ′, the printed circuit 3 (the signal circuit 3a and the ground circuit 3b), and the insulating film 4 constitute the base film 5 ′.

  The double-sided shielded FPC 10B of FIG. 4C is provided with an insulation removal portion 4a and an insulation removal portion 2a ′ on the insulating film 4 and base film 2 ′ side above and below the ground circuit 3b as in the example of FIG. 4B. However, the ground circuit 3b is further provided with a through-hole 3d 'to form a ground circuit 3b'. The adhesive layer 8a also enters the through-hole 3d 'from both sides and joins at the interface s. The ground circuit 3 ′ is connected to the adhesive layer 8 a at the non-insulating portion 3 c and the through hole inner surface 3 c ′ on the upper surface. Here, the base film 2 ′, the printed circuit 3 ′ (the signal circuit 3a ′ and the ground circuit 3b ′), and the insulating film 4 constitute the base film 5 ″.

  Next, the results of evaluation tests conducted on the examples of the present invention will be described together with comparative examples.

(About test piece)
Shield film 1 (separate film 6a, release layer 6b, protective layer 7, electromagnetic wave shield layer 8 (conductive adhesive layer 8a) having the characteristics described in Comparative Examples 1 and 2 and Examples 1 to 18 shown in FIG. The metal layer 8b)) is used. Each test piece has a rectangular shape having a length of 200 mm and a width of 50 mm.
The PET of the separate film 6a in Examples 1 to 18 is subjected to mat processing. In Examples 1 to 12, sand mats are used, in Examples 13 and 16, etching mats are used, and Examples 14 and Examples are used. No. 17 was a coating mat, and Examples 15 and 18 were kneaded mats. Moreover, PET of the separate film 6a in Comparative Examples 1 and 2 is a clear type that is not matted.
Moreover, as a measuring method of the surface roughness (Ra (micrometer)) in Comparative Examples 1 and 2 and Examples 1-18, it measures with a stylus type surface roughness measuring meter. This is a probe that traces the surface of an object, and the needle moves up and down in accordance with the unevenness of the surface of the object. And it is the method of measuring the roughness of the surface of an object by measuring the movement of the needle.
Moreover, the kind of mold release layer 6b uses the melamine mold release agent (A type) in the comparative example 1, Examples 1-8, and Examples 13-15, and the comparative example 2, Examples 9- In Examples 12 and 16 to 18, an acrylic release agent (B type) was used, and the amount of adhesion was unified to 1.2 g / m ² . As a method for measuring the adhesion amount of the release layer, first, the solid content concentration of the release agent is measured using an infrared moisture meter. Next, after coating the release agent, the amount of the release agent used is divided by the processing quantity m ² to obtain the wet adhesion amount. Next, the amount of dry adhesion is determined from the amount of wet adhesion and the solid content concentration of the release agent, and this amount of dry adhesion is used as the amount of adhesion of the release agent in this test.

(1) Separation test of separate film against protective layer (Test method)
In the measurement of the peel strength before pressing (before heating / pressing), a double-sided tape is applied to the surface of the conductive adhesive layer 8a of the shield films 1 according to Comparative Examples 1 and 2 and Examples 1 to 18, Attach one side of the double-sided tape to the base of the tester (PAFTEK PFT-50S peel strength tester) to secure the shield film 1. And as shown in FIG. 7, the edge part of the separate film 6a of the shield film 1 is set to the chuck | zipper of a testing machine, and the peeling strength with respect to the protective layer 7 of the separate film 6a is measured. Here, as peeling conditions, as shown in FIG. 7, the peeling angle is 170 °, and the peeling speed of the separate film 6a by the chuck is 1000 mm / min. The test is performed 5 times, and the average of the minimum peel strength values obtained in each round is calculated as the peel strength value (N / 50 mm).

On the other hand, in the measurement of peel strength after pressing (after heating and pressurization), the surface of the conductive adhesive layer 8a of the shield films 1 according to Comparative Examples 1 and 2 and Examples 1 to 18 is defined as a polyimide surface. It heat-presses with a press to the polyimide surface side of the copper clad laminated board which has a copper foil surface. As thermocompression bonding conditions in the press machine at this time, the pressure is preferably 2 to 5 MPa, the temperature is 140 to 180 ° C., and the time is preferably 3 to 60 minutes. In this measurement, thermocompression bonding is performed by setting the set temperature to 170 ° C., applying a load for 60 sec at 0.5 MPa, and then applying a load for 180 sec at 3.0 MPa.
Then, a double-sided tape is attached to the copper foil side of the copper-clad laminate on which the shield film 1 is thermocompression-bonded. ) And the shield film 1 is fixed. After that, the peel strength value (N / 50 mm) is calculated in the same manner as the test method described in the measurement of the peel strength before pressing.

(2) Evaluation method The evaluation method of the peeling test of the separate film with respect to the said protective layer is demonstrated. In the peel test of the separate film, when the peel strength before pressing is smaller than 1 N / 50 mm, the evaluation is determined as “x”. If the peel strength value before pressing is 1 to 20 N / 50 mm and the peel strength value after pressing is 1 to 10 N / 50 mm, the evaluation is determined as “◯ (single circle)”. Here, as a condition for evaluating “◯”, the value of the peel strength before pressing was set to 1 to 20 N / 50 mm when the value of the peel strength was smaller than 1 N / 50 mm when immersed in a chemical solution. If the separation film is peeled off from the protective layer, and the peel strength value is larger than 20 N / 50 mm, the adhesion of the separate film to the protective layer is too strong, and the protective film is peeled off when the separate film is peeled off. This is because the protective layer is broken. In addition, as a condition for evaluating “◯”, the peel strength value after pressing was set to 1 to 10 N / 50 mm. When the peel strength value was smaller than 1 N / 50 mm, the separate film was protective layer after pressing. On the other hand, if the peel strength value is larger than 10 N / 50 mm, the workability when the person or the manufacturing apparatus peels the separate film from the protective layer is deteriorated. Yes (when peeling the separate film from the protective layer, it cannot be removed smoothly without using unnecessary force). Furthermore, in addition to the conditions of evaluation “◯”, in the shield film after pressing, if the peel strength value after pressing is 1 to 4 N / 50 mm, the separation film can be peeled off more smoothly, and the evaluation is “◎ (Double circle) ”.

  FIG. 6 shows the test results and determinations according to Comparative Examples 1 and 2 and Examples 1 to 18 described above.

  As is clear from the results and determination of the shield film peeling test shown in FIG. 6, the shield films 1 of Comparative Examples 1 and 2 using a clear type of PET that has not been matted are peeled before and after pressing. Since the strength is less than 1 N / 50 mm, even if the type of release agent is changed (Comparative Example 1 is a melamine release agent and Comparative Example 2 is an acrylic release agent), the separate film 6a is protected when immersed in a chemical solution. There is a possibility that the separation film 6a peels off from the layer 7 or the separation film 6a naturally peels off from the protective layer 7 after pressing, whereas the PET is matted (sand matting in Examples 1 to 12, Example 13 and Example 16 are Etching mat, Examples 14 and 17 are coating mats, and Examples 15 and 18 are kneading mats). Since the peel film 1 has a peel strength before pressing of 1 to 20 N / 50 mm and a peel strength after pressing of 1 to 10 N / 50 mm, even if the type of the release agent is changed (Examples 1 to 8 and execution) Examples 13 to 15 are melamine release agents, Examples 9 to 12 and Examples 16 to 18 are acrylic release agents), the separate film 6a does not peel from the protective layer 7 when immersed in a chemical solution or after pressing. In other words, it can be seen that the peel strength cannot be controlled even if the release film 6a is applied to the separate film 6a that has not been matted, and the penetration of the chemical is allowed.

  Further, as apparent from the peel strength values of Examples 1 to 8, the mat processing roughness was 1.000 μm → 0.853 μm → 0.679 μm → 0.489 μm → 0.352 μm → 0.308 μm → 0. By changing from 253 μm to 0.200 μm, the peel strength before press: 19.87 N / 50 mm (after press: 9.92 N / 50 mm) → before press: 9.48 N / 50 mm (after press: 5.67 N / 50 mm) ) → Before pressing: 7.12 N / 50 mm (After pressing: 4.89 N / 50 mm) → Before pressing: 4.97 N / 50 mm (After pressing: 3.50 N / 50 mm) → Before pressing: 3.42 N / 50 mm (Pressing) After: 2.78 N / 50 mm) → Before pressing: 2.18 N / 50 mm (After pressing: 1.52 N / 50 mm) → Before pressing: 1.55 N / 50 mm (After pressing: 1.15 N / 50 mm) Press before: 1.12N / 50mm (after pressing: 1.00N / 50mm) it can be seen that is smaller and so on. Thereby, it turns out that peeling strength can be controlled by changing the roughness of mat processing. This also applies to the results of Examples 9 to 12 in which the type of the release agent is changed (the value of the peel strength is reduced by changing the mat processing roughness value to be smaller). )

  In addition, when Examples 1 to 8 using a melamine release agent as a release agent and Examples 9 to 12 using an acrylic release agent as a release agent are seen, an acrylic release is used as the release agent. It can be seen that when the agent is used, the peel strength value before pressing and the peel strength value after pressing are higher than when the melamine release agent is used as the release agent. Further, a comparison between Example 13 (etching mat, surface roughness 0.418 μm, melamine release agent) and Example 16 (etching mat, surface roughness 0.418 μm, acrylic release agent), Example Comparison between 14 (coating mat, surface roughness 0.362 μm, melamine release agent) and Example 17 (coating mat, surface roughness 0.362 μm, acrylic release agent) and Example 15 (kneading) A comparison of the mat with a surface roughness of 0.245 μm and a melamine release agent) and Example 18 (kneading mat with a surface roughness of 0.245 μm and an acrylic release agent) shows a release agent. It can be seen that when an acrylic release agent is used, the peel strength value before pressing and the peel strength value after pressing are higher than when a melamine release agent is used as the release agent. . Thereby, it turns out that the value of peel strength can be controlled also by changing the kind of release agent.

Moreover, when Examples 1-18 are looked at, when the range of surface roughness exists in the range of 0.2 micrometer-1 micrometer, evaluation has acquired the determination of "(circle)". If the surface roughness is a value smaller than 0.2 μm, the surface of the protective layer (hard layer) is not uneven enough to exert the anchor effect, and the peel strength of the separate film to the protective layer cannot be controlled. It depends. On the other hand, when the surface roughness is larger than 1.0 μm, the anchor effect due to the unevenness on the surface of the protective layer (hard layer) works strongly (adhesion becomes strong), and protection is achieved when the separate film is peeled off from the protective layer. This is due to the fact that even the layer is peeled off.
Moreover, when peeling the separate film 6a from the protective layer 7, the shield film 1 according to Examples 1 to 18 can be peeled off without breaking the protective layer itself, and can be peeled off smoothly without using unnecessary force. It means you can do it.

  Moreover, in Examples 4-8 and Examples 12-18, evaluation "(double-circle)" is obtained by determination. Thereby, when the value of peel strength after pressing is between 1 and 4 N / 50 mm, it can be seen that the separate film can be peeled off more smoothly when the separate film is peeled off from the protective layer.

  As described above, the shield film 1 of the present embodiment has a resin film on the side of the separate film 6a having the concavo-convex portion 61 formed on one side thereof, on the surface side where the concavo-convex portion 61 is formed, via the release layer 6b. The protective layer 7 is formed by coating, the electromagnetic wave shielding layer 8 is further formed, and the surface roughness (Ra) of the protective layer 7 (hard layer 7a) when the separate film 6a is peeled from the protective layer 7 is set to 0. 2 μm to 1.0 μm. According to this, in the state where the separate film 6a is adhered to the protective layer 7 via the release layer 6b, the uneven portion 61 on the surface of the separate film 6a and the uneven portion 61 on the surface of the separate film 6a are transferred and formed. Further, the adhesion of the separate film 6a to the protective layer 7 is shielded in a later step by the anchor effect of the uneven portion 71 on the surface of the protective layer 7 (hard layer 7a) having a surface roughness (Ra) of 0.2 μm to 1.0 μm. When the film 1 is immersed in the chemical solution, the chemical solution does not enter between the protective layer 7 and the separate film 6a, and the separation film 6a can be prevented from peeling off from the protective layer 7. Further, the protective layer 7 (hard layer) having a surface roughness (Ra) of 0.2 μm to 1.0 μm formed by transferring the uneven portion 61 on the surface of the separate film 6a and the uneven portion 61 on the surface of the separate film 6a. 7a) By providing the uneven portion 71 on the surface, the release agent applied to the separate film 6a having the uneven portion 61 is naturally dispersed in the process of applying the release agent to the separate film 6a. It is possible to form the release layer 6b in a state where is distributed in a substantially uniform manner. Thereby, the adhesiveness of the separate film 6a to the protective layer 7 can be suppressed to such an extent that the protective layer 7 itself is not broken by an excessively large adhesive force when peeling the separate film 6a from the protective layer 7. Thus, since the adhesive force with respect to the protective layer 7 of the separate film 6a can be controlled moderately, the malfunction by adhering with an excessively large adhesive force or an excessively small adhesive force can be prevented.

  Moreover, in the shield film 1 of this embodiment, the peeling strength with respect to the protective layer 7 of the separate film 6a is made into the range of 1N / 50mm-20N / 50mm. According to this, the adhesive force with respect to the protective layer 7 of the separate film 6a can be optimized more.

  Moreover, the shield film 1 of the present embodiment has a peel strength with respect to the protective layer 7 of the separate film 6a after the shield film 1 is heated and pressurized to the base film 5 in a range of 1 N / 50 mm to 10 N / 50 mm. . According to this, the adhesive force with respect to the protective layer 7 of the separate film 6a can be optimized more.

  Further, in the shield film 1 of the present embodiment, the electromagnetic wave shielding layer 8 includes the conductive adhesive layer 8a, so that the ground circuit 3b and the electromagnetic wave shielding layer 8 can be reliably electrically connected.

  Moreover, in the shield film 1 of this embodiment, the electromagnetic wave shielding layer 8 further includes a metal layer 8b, and an anisotropic conductive adhesive is used for the conductive adhesive layer 8a, thereby reducing the amount of the conductive filler. By reducing the number, the flexibility can be improved.

  Further, in the shield film 1 of the present embodiment, by using isotropic conductive adhesive for the conductive adhesive layer 8a, it is possible to connect the ground to the ground circuit 3b only by providing the conductive adhesive layer 8a. In addition, an electromagnetic wave shielding effect can be provided.

  Moreover, in this embodiment, on the surface side where the said uneven | corrugated | grooved part 61 of the separate film 6a in which the uneven | corrugated | grooved part 61 was formed in the whole one surface on at least one side of the base film 5 containing the one or more printed circuit 3 was formed. The protective film 7 is formed by coating the resin through the release layer 6b, and the shield flexible printed wiring board 10 provided with the shield film 1 on which the electromagnetic wave shield layer 8 is further formed is formed by separating the separate film 6a with the protective layer 7 The surface roughness (Ra) of the protective layer 7 (hard layer 7a) when peeled from the substrate is in the range of 0.2 μm to 1.0 μm. According to this, regarding the shielded flexible printed wiring board 10 having the electromagnetic wave shielding layer 8 and the protective layer 7 on one surface of the base film 5, the adhesive force of the separate film 6a to the protective layer 7 can be appropriately controlled. Therefore, it is possible to prevent problems caused by bonding with an excessively large adhesive force or an excessively small adhesive force.

  Moreover, since the base film 5 including the printed circuit 3 is made of a flexible printed wiring board, the shielded flexible printed wiring board 10 of the present embodiment can be made excellent in flexibility.

  Moreover, since the base film 5 including the printed circuit 3 can be a TAB tape for a tape carrier package, the shielded flexible printed wiring board 10 according to the present embodiment is flexible and excellent in embeddability. Can be obtained.

  Moreover, in the manufacturing method of the shield flexible printed wiring board 10 which concerns on this embodiment, the release layer 6b and protection are carried out to the surface by the side of the said uneven | corrugated | grooved part 61 in the separate film 6a in which the uneven | corrugated | grooved part 61 was formed in the whole one surface by mat | matte process. The shield film 1 in which at least the layer 7 and the electromagnetic wave shield layer 8 are laminated is placed on at least one surface of the base film 5 including one or more printed circuits 3, and the shield film 1 and the base film 5 are heated in the stacking direction. After pressurization, the separate film 6a was peeled from the protective layer 7 so that the surface roughness (Ra) had the protective layer 7 of 0.2 μm to 1.0 μm. According to the above method, since the adhesive force of the separate film 6a to the protective layer 7 can be appropriately controlled, it is possible to prevent problems caused by bonding with an excessively large adhesive force or an excessively small adhesive force.

DESCRIPTION OF SYMBOLS 1,1 'Shield film 2, 2' Base film 2a 'Insulation removal part 3, 3' Print circuit 3a, 3a 'Signal circuit 3b, 3b' Ground circuit 3c, 3c 'Non-insulation part 3d' Through-hole 4 Insulation film 4a Insulation removal part 5,5 ', 5''Base film 6a Separate film 6b Release layer 7 Protective layer 7a Hard layer 7b Soft layer 8, 8' Electromagnetic wave shielding layer 8a Adhesive layer 8a 'Adhesive 8b Metal layer 9, 9 'Shield film body 10 Shield flexible printed wiring board 10' Shield FPC
10A Double-sided shielded FPC
10B Double-sided shielded FPC
11 Metal foil 12 Adhesive resin layer 13 Ground member 13a Ground member 71 Uneven portion 71a Convex portion 71b Concavity s Interface

Claims (10)

A shield film in which a protective layer is formed by coating a resin with a release agent on the surface side of the separation film having a concavo-convex portion formed on the entire surface thereof, and an electromagnetic wave shielding layer is further formed. A film,
The surface roughness (Ra) of the protective layer when the separate film is peeled from the protective layer is 0.2 μm to 1.0 μm,
The thermocompression bonding conditions for placing the shield film on a printed wiring board and pressurizing the shield film while heating the shield film are as follows: the pressure is 2 to 5 MPa, the temperature is 140 to 180 ° C., and the time is 3 ~ 60 minutes,
By placing the shield film on the printed wiring board, peel strength to the protective layer of the separate film before pressurizing to the printed wiring board side while heating the shield film, 1N / 50mm~20N / 50mm,
By placing the shield film on the printed wiring board, in the thermocompression bonding conditions, the peel strength with respect to the protective layer of the separate film after pressurized to the printed wiring board side while heating the shielding film Is 1 N / 50 mm to 10 N / 50 mm,
The peel strength of the separate film to the protective layer before being pressed to the printed wiring board side while heating the shield film is applied to the printed wiring board side while heating the shield film under the thermocompression bonding conditions. Greater than the peel strength to the protective layer of the separate film after pressing,
Shield film characterized by that.   The shield film according to claim 1, wherein the electromagnetic wave shielding layer includes a conductive adhesive layer. The electromagnetic wave shielding layer further includes a metal layer,
The said conductive adhesive layer is comprised by the anisotropic conductive adhesive layer, The shield film of Claim 2 characterized by the above-mentioned.   The shield film according to claim 2, wherein the conductive adhesive layer is formed of an isotropic conductive adhesive layer.   5. The shield film according to claim 1, wherein an uneven portion is formed on the surface of the protective layer on the side of the separate film by transferring the uneven portion.   6. The shield film according to claim 1, wherein the uneven portion of the separate film is formed by performing a mat treatment. On at least one side of the substrate including one or more printed circuits,
A shield film in which a protective layer is formed by coating a resin with a release agent on the surface side of the separation film having a concavo-convex portion formed on the entire surface thereof, and an electromagnetic wave shielding layer is further formed. A shield printed wiring board provided with a film,
The surface roughness (Ra) of the protective layer when the separate film is peeled from the protective layer is 0.2 μm to 1.0 μm,
The thermocompression bonding conditions for placing the shield film on a printed wiring board and pressurizing the shield film while heating the shield film are as follows: the pressure is 2 to 5 MPa, the temperature is 140 to 180 ° C., and the time is 3 ~ 60 minutes,
By placing the shield film on the printed wiring board, peel strength to the protective layer of the separate film before pressurizing to the printed wiring board side while heating the shield film, 1N / 50mm~20N / 50mm,
By placing the shield film on the printed wiring board, in the thermocompression bonding conditions, the peel strength with respect to the protective layer of the separate film after pressurized to the printed wiring board side while heating the shielding film Is 1 N / 50 mm to 10 N / 50 mm,
The peel strength of the separate film to the protective layer before being pressed to the printed wiring board side while heating the shield film is applied to the printed wiring board side while heating the shield film under the thermocompression bonding conditions. Greater than the peel strength to the protective layer of the separate film after pressing,
Shield printed wiring board characterized by the above.   The shield printed wiring board according to claim 7, wherein the substrate including the printed circuit is a flexible printed wiring board.   The shield printed wiring board according to claim 7, wherein the substrate including the printed circuit is a TAB tape for a tape carrier package. A shield film in which a protective layer is formed by coating a resin with a release agent on the surface side of the separation film having a concavo-convex portion formed on the entire surface thereof, and an electromagnetic wave shielding layer is further formed. A laminating step of laminating a film on at least one side of a substrate including one or more printed circuits;
After the laminating step, heating and pressurizing are performed while the shield film and the substrate are heated in the laminating direction under thermocompression bonding conditions in which the pressure is 2 to 5 MPa, the temperature is 140 to 180 ° C., and the time is 3 to 60 minutes. Pressure step, and after the heating and pressurizing step, including a peeling step of peeling the separate film from the protective layer,
The peel strength of the separate film before the heating / pressurizing step with respect to the protective layer is 1 N / 50 mm to 20 N / 50 mm,
The peel strength of the separate film after the heating / pressurizing step under the thermocompression bonding condition with respect to the protective layer is 1 N / 50 mm to 10 N / 50 mm,
The surface roughness (Ra) of the protective layer after the peeling step is 0.2 μm to 1.0 μm,
The peel strength of the separate film to the protective layer before being pressed to the printed wiring board side while heating the shield film is applied to the printed wiring board side while heating the shield film under the thermocompression bonding conditions. Greater than the peel strength to the protective layer of the separate film after pressing,
A method for producing a shielded printed wiring board, comprising: