TWI700984B - Shielding film for printed wiring board and printed wiring board - Google Patents

Abstract

The present invention is to provide a shielding film for a printed wiring board and a printed wiring board that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm).

The shielding film (10) for printed wiring boards is provided with a metal layer (2) formed on one side of the insulating layer (1). The arithmetic average roughness of one side of the insulating layer (1) (JIS B 0601 (1994)) is 0.5~5.0μm, and the metal layer (2) is formed along one surface of the insulating layer (1) to become a bellows structure. In the printed wiring board of the present invention, a shielding film (10) for a printed wiring board is attached to a base film.

Description

Shielding film for printed wiring board and printed wiring board

The present invention relates to a shielding film for a printed wiring board and a printed wiring board used in devices such as computers, communication equipment, and cameras.

Conventionally, shielding films for printed wiring boards using metal layers are known. For example, there is one disclosed in Patent Document 1 below. Patent Document 1 discloses that a metal film sheet for transfer that can be easily transferred to FPC or the like is characterized in that a metal layer is provided on at least one surface area of a synthetic resin sheet base material, and the metal layer and the synthetic resin sheet The transfer metal film sheet with a peel strength of 5N/cm or less and a conductive adhesive layer is characterized in that metal powder, carbon powder, metal powder or carbon powder are used on the surface of the metal layer of the transfer metal film sheet The undispersed conductive adhesive is laminated on the resin composition.

[Patent Document 1] JP 2006-297714 A

In recent years, in devices such as computers, communication equipment, and video cameras, there is a demand for shielding films for printed wiring boards and printed wiring boards that are more resistant to repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). .

However, although Patent Document 1 has a certain degree of flexibility, it has not been considered for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm). Repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm) may cause damage to the metal layer, and may reduce the electromagnetic wave shielding characteristics.

Therefore, the object of the present invention is to provide a shielding film and printing for printed wiring boards that are less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). Wiring board.

(Means and effects to solve the problem)

(1) The shielding film for a printed wiring board of the present invention is provided with a first metal layer formed on one side of the insulating layer, and the arithmetic average roughness of one side of the insulating layer (JIS B 0601 (1994)) is 0.5 to 5.0 μm, and the first metal layer is formed so as to form a bellows structure along one surface of the insulating layer.

According to the above-mentioned structure, since the metal layer has a bellows structure with high bendability, it is possible to provide a method for repeated bending and sliding from a large bending radius to a small bending radius (1.0mm), which is less likely to produce metal Shielding film for printed wiring boards for layer destruction. Therefore, it is possible to provide a shielding film for a printed wiring board whose electromagnetic wave shielding characteristics are not easily reduced. In addition, when it is attached to a printed wiring board for use, the printed wiring board can be protected, and even if the printed wiring board is repeatedly bent and slid, the electromagnetic wave shielding characteristics can be maintained.

(2) In the shielding film for a printed wiring board of (1), the arithmetic average thickness of the surface of the first metal layer opposite to the insulating layer is 0.5 to 5.0 μm.

According to the above-mentioned structure, a bellows structure of a better shape can be formed, and the effect of (1) mentioned above can be exhibited more reliably.

(3) In the shielding film for printed wiring boards of (1) or (2), it is preferable that the first metal layer is made of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, or zinc. And any material layer containing any one or more alloys of these materials.

With the above configuration, a metal layer with high electromagnetic wave shielding characteristics can be obtained. In addition, when another metal layer made of a different material is formed on the surface of the metal layer, it becomes one that is easy to alloy.

(4) In the shielding film for a printed wiring board of (1) or (2), it is preferable that the first metal layer is a layer formed of one or more types of scaly metal particles.

With the above-mentioned structure, when the printed wiring board is attached and used by pressing and pressing at a predetermined temperature (for example, 150°C) or higher, a gap can be formed between the scaly metal particles, and at the same time, metal bonding is also generated. The metal layer is formed to be electrically connected, so it can become a more flexible conductive layer. Therefore, when used in a printed wiring board as described above, it is possible to provide a printed wiring that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). Shielding film for board.

(5) In the shielding film for a printed wiring board of (1) or (2), it is preferable that a conductive adhesive layer is formed on the side of the first metal layer opposite to the insulating layer.

According to the above configuration, it can be easily attached to a printed wiring board, and can be used as a layer having an electromagnetic wave shielding effect in addition to being used as an adhesive layer. Furthermore, in the shielding film for printed wiring boards of (4) above, when the printed wiring board is pressed and pressed for use, the conductive adhesive layer is filled in the gaps between the scaly metal particles, which can make the metal layer Strength and flexibility are improved.

(6) In addition, in the shielding film for a printed wiring board of (1) or (2), the first metal layer is a porous layer having plural holes, and the first metal layer is opposite to the insulating layer A conductive adhesive layer is formed on the side.

According to the above-mentioned structure, when the printed wiring board is pressed and pressed for pasting use, the conductive adhesive layer is filled in the voids of the holes, and the strength and flexibility of the metal layer can be improved.

(7) Furthermore, in the shielding film for a printed wiring board of (1) or (2), the first metal layer is formed on the side opposite to the insulating layer using nickel, copper, silver, tin, gold, The second metal layer of any one of palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these materials, wherein the first metal layer and the second metal layer are made of different types of materials .

According to the above configuration, the second metal layer can achieve the effect of preventing corrosion of the metal layer 12. In addition, when the printed wiring board is attached and used by pressure pressing at a predetermined temperature (for example, 150°C) or higher, an intermetallic compound may be formed between the first metal layer and the second metal layer. As a result, when the printed wiring board is pasted and used by pressure pressing at a predetermined temperature or higher, it can be a shielding film for printed wiring boards with improved strength and flexibility.

(8) In the shielding film for a printed wiring board of (7), it is preferable that the second metal layer is a layer formed of one or more types of scaly metal particles.

With the above-mentioned structure, when the printed wiring board is attached and used by pressure pressing at a predetermined temperature (for example, 150°C) or higher, a gap can be formed between the scaly metal particles constituting the second metal layer. It also produces intermetallic bonding to form an electrically connected metal layer, so it can become a more flexible conductive layer. Therefore, when used in a printed wiring board as described above, it is possible to provide a printed wiring that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). Shielding film for board.

(9) In the shielding film for a printed wiring board of (8), it is preferable that a conductive adhesive layer is formed on the side of the second metal layer opposite to the insulating layer.

According to the above configuration, it can be easily attached to a printed wiring board, and can be used as a layer having an electromagnetic wave shielding effect in addition to being used as an adhesive layer. When the printed wiring board is pressed and pressed for attaching, the conductive adhesive layer is filled in the gaps between the scaly metal particles, which can improve the strength and flexibility of the metal layer.

(10) In addition, in the shielding film for a printed wiring board of (7) above, the second metal layer may be a porous layer having a plurality of pores, and the second metal layer may be formed on the side opposite to the insulating layer. Conductive adhesive layer.

According to the above-mentioned structure, when the printed wiring board is pressed and pressed for pasting, a part of the conductive adhesive layer will be filled in the voids of the second metal layer, and the strength and flexibility of the metal layer can be made Sexual improvement.

(11) In the shielding film for printed wiring boards of the above (1) or (2), it is preferable that the first metal layer is a porous layer having a plurality of pores or is formed of one or more scaly metal particles Floor.

With the above-mentioned structure, when the printed wiring board is pressed and pressed for application, when the first metal layer is a porous layer with a plurality of pores, the gaps of the pores are filled with a part of the conductive adhesive layer , When it is a layer formed by more than one type of scaly metal particles, the gap between the scaly metal particles is filled with a part of the conductive adhesive layer, which can increase the strength and flexibility of the first metal layer .

(12) From another point of view, the shielding film for a printed wiring board of the present invention may include: a first metal layer formed on one side of the insulating layer; and a first metal layer formed on the side opposite to the insulating layer of the first metal layer 2 metal layers, the first metal layer and the second metal layer are any one of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these materials A layer of materials, and is composed of different kinds of materials.

According to the above configuration, the second metal layer can achieve the effect of preventing corrosion of the metal layer 12. In addition, when the printed wiring board is attached and used by pressure pressing at a predetermined temperature (for example, 150°C) or higher, an intermetallic compound may be formed between the first metal layer and the second metal layer. As a result, when the printed wiring board is pasted and used by pressure pressing at a predetermined temperature or higher, it can be a shielding film for printed wiring boards with improved strength and flexibility. Therefore, it is possible to provide a shielding film for a printed wiring board that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm).

(13) In the shielding film for a printed wiring board according to (12), it is preferable that the second metal layer is a layer formed of one or more types of scaly metal particles.

With the above-mentioned structure, when the printed wiring board is used by pressure pressing at a predetermined temperature (for example, 150°C) or higher, a gap can be formed between the scaly metal particles constituting the second metal layer. Intermetallic bonding is generated to form a metal layer that is electrically connected, so it can become a more flexible conductive layer. Therefore, it is possible to provide a shielding film for a printed wiring board that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm).

(14) In the shielding film for a printed wiring board of (13), it is preferable that a conductive adhesive layer is formed on the side of the second metal layer opposite to the insulating layer.

According to the above configuration, it can be easily attached to a printed wiring board. When the printed wiring board is pressed and pressed for attaching, the conductive adhesive layer is filled in the gaps between the scaly metal particles, which can improve the strength and flexibility of the metal layer.

(15) In addition, in the shielding film for a printed wiring board of (12), the second metal layer may be a porous layer having a large number of pores, and the second metal layer may be formed on the side opposite to the insulating layer. Conductive adhesive layer.

According to the above structure, when the printed wiring board is pressed and pressed for use, a part of the conductive adhesive layer will be filled in the voids of the holes of the second metal layer, and the strength and flexibility of the second metal layer can be made Sexual improvement.

(16) In the shielding film for a printed wiring board of (14) or (15), the first metal layer may be a porous layer having a plurality of pores or a layer formed of one or more types of scaly metal particles.

With the above-mentioned structure, when the printed wiring board is pressed and pressed for application, when the first metal layer is a porous layer with a plurality of pores, a part of the conductive adhesive layer existing in the pores will pass through Where the second metal layer is filled, when the first metal layer is a layer formed of one or more scaly metal particles, there is a part of the conductive adhesive layer in the gap between the scaly metal particles. By filling the place with the second metal layer, the strength and flexibility of the first metal layer can be improved.

(17) From another viewpoint, the shielding film for a printed wiring board of the present invention may include a metal layer formed on one side of the insulating layer, and the metal layer is a layer formed of one or more types of scaly metal particles.

With the above-mentioned structure, when it is applied by pressing and pressing at a predetermined temperature (for example, 150°C) or higher, gaps can be formed between the scaly metal particles, and metal-to-metal bonding can be formed to form an electrical connection. The metal layer can therefore become a more flexible conductive layer. Therefore, it is possible to provide a shielding film for a printed wiring board that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm).

(18) In the shielding film for a printed wiring board of (17), it is preferable that a conductive adhesive layer is formed on the side of the metal layer opposite to the insulating layer.

According to the above configuration, it can be easily attached to a printed wiring board. In addition, when the printed wiring board is pressed and pressed for pasting use, the conductive adhesive layer is filled in the gaps between the scaly metal particles, and the strength and flexibility of the metal layer can be improved.

(19) In addition, from another point of view, the shielding film for a printed wiring board of the present invention may include a metal layer formed on one side of the insulating layer. The metal layer is a porous layer having a plurality of pores, and the metal layer is insulated from the metal layer. A conductive adhesive layer is formed on the side opposite to the layer.

According to the above configuration, when the printed wiring board is pressed and pressed for pasting use, a part of the conductive adhesive layer is filled in the gaps of the holes of the metal layer, and the strength and flexibility of the metal layer can be improved. Therefore, it is possible to provide a shielding film for a printed wiring board that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm).

(20) In the above-mentioned (1), (2), (12)~(15), (17)~(19) shielding films for printed wiring boards, the lower limit of the bending radius can be repeated up to 1.0mm Shielding film for bending and sliding.

(21) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more printed circuits, and the shielding film for a printed wiring board described in (1) or (2) is coated on the first metal It is formed by pasting the conductive adhesive of the layer.

(22) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more printed circuits, and the shielding film for a printed wiring board described in (5) above is formed by applying the conductive film on the first metal layer. A part of the conductive adhesive layer will be filled in the gaps between the scaly metal particles.

(23) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more layers of printed circuits, and the shielding film for a printed wiring board described in (6) above is through the conductive layer coated on the first metal layer. A part of the conductive adhesive layer will be filled in the voids of the holes.

(24) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more layers of printed circuits, and the shielding film for printed wiring boards described in (1), (2), and (12) above is applied to A conductive adhesive for the second metal layer is attached, and between the first metal layer and the second metal layer, a material for forming the first metal layer and a material for forming the second metal layer are provided. Intermetallic compound layer of material.

(25) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more layers of printed circuits, and the shielding film for printed wiring boards described in (1), (2), and (13) is coated on The conductive adhesive of the second metal layer is pasted, and the second metal layer is an intermetallic bonding layer between one or more scaly metal particles.

(26) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more printed circuits, and the masking film for printed wiring boards described in (1), (2), and (14) above is coated on The conductive adhesive of the second metal layer is attached, and a part of the conductive adhesive layer is filled in the gaps of the scaly metal particles.

(27) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more printed circuits, and the masking film for printed wiring boards described in (1), (2), and (15) above is applied to The conductive adhesive of the second metal layer is attached, and a part of the conductive adhesive layer is filled in the gap of the hole.

(28) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more printed circuits, and the shielding film for a printed wiring board described in (11) above is formed by applying the conductive layer on the second metal layer. A part of the conductive adhesive layer is filled in the gaps of the scaly metal particles or the gaps of the holes in the first metal layer.

(29) The printed wiring board of the present invention is provided on at least one side of a substrate containing one or more layers of printed circuits, and the shielding film for a printed wiring board described in (16) above is formed through the conductive layer coated on the second metal layer. A part of the conductive adhesive layer is filled in the gaps of the scaly metal particles or the gaps of the holes in the first metal layer.

(30) The printed wiring board of the present invention is on at least one side of a substrate containing one or more printed circuits, and the shielding film for a printed wiring board described in (17) above is a conductive adhesive coated on the metal layer The metal layer is an intermetallic bonding layer between one or more scaly metal particles.

(31) The printed wiring board of the present invention is on at least one side of a substrate containing one or more printed circuits, and the shielding film for a printed wiring board described in (18) above is a conductive adhesive coated on the metal layer A part of the conductive adhesive layer will be filled in the gaps of the scaly metal particles.

(32) The printed wiring board of the present invention is on at least one side of a substrate containing one or more layers of printed circuits, and the shielding film for a printed wiring board described in (19) above is a conductive adhesive coated on the metal layer A part of the conductive adhesive layer will be filled in the gap of the hole.

According to the above-mentioned constitutions (21) to (32), it is possible to provide a printed wiring board having various effects of the shielding film for printed wiring boards of (1) to (19). In particular, it is possible to provide a printed wiring board that is physically protected even for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm), the electromagnetic wave shielding characteristics are not reduced.

1, 11, 21, 31, 41, 61a, 71a, 71b, 81‧‧‧Insulation layer

2, 12, 13, 22, 32, 33, 42, 62a, 62b, 82‧‧‧Metal layer

10, 20, 30, 40, 50, 60, 70a, 70b, 80a, 80b, 90‧‧‧Shielding film for printed wiring boards

43, 63, 74‧‧‧ base film

44、84‧‧‧Printed circuit

44a‧‧‧Signal circuit

44b, 64b, 75b‧‧‧Grounding circuit

44c, 64c‧‧‧non-insulating part

45, 65, 76, 85‧‧‧Insulating film

45a, 63a, 65a, 74a, 76a‧‧‧Insulation removal part

46, 66, 77, 86‧‧‧Matrix film

47, 67, 68, 78, 79, 87‧‧‧ Adhesive layer

48a‧‧‧Separation film

48b‧‧‧Release layer

49‧‧‧Press

75d‧‧‧through hole

91‧‧‧Metal foil

92‧‧‧Adhesive resin layer

93, 93a‧‧‧Grounding member

78a, 93a‧‧‧location

100, 101, 102, 103, 104, 111‧‧‧Printed wiring board

121‧‧‧Fixed plate

122‧‧‧sliding plate

Fig. 1 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a first embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a second embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a third embodiment of the present invention.

Fig. 4 is a schematic diagram of a scaly metal particle group forming a metal layer of the shielding film for a printed wiring board shown in Fig. 3.

Fig. 5 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a fourth embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view showing steps in a manufacturing method of a printed wiring board according to a fifth embodiment of the present invention.

Fig. 7 is a shielding film body for a printed wiring board according to a fifth embodiment.

Fig. 8 is a schematic cross-sectional view of a printed wiring board according to a sixth embodiment of the present invention.

Fig. 9 is a schematic cross-sectional view of a printed wiring board according to a seventh embodiment of the present invention.

Fig. 10 is a schematic cross-sectional view of a printed wiring board according to an eighth embodiment of the present invention.

Fig. 11 is a schematic cross-sectional view of a printed wiring board according to a ninth embodiment of the present invention.

Fig. 12 is a diagram showing a test method of a bending resistance test.

Fig. 13 (a) is an SEM photograph showing the shielding film for a printed wiring board of Example 1 of the present invention, and (b) is a schematic diagram showing the photographing direction of the SEM photograph of (a).

<First Embodiment>

The shielding film for printed wiring boards related to the first embodiment of the present invention will be described. Fig. 1 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a first embodiment of the present invention.

The shielding film 10 for a printed wiring board shown in FIG. 1 is provided with the metal layer 2 of a bellows structure on one surface of the insulating layer 1 (the arithmetic mean surface thickness (JIS B 0601 (1994)) is 0.5-5.0 micrometers).

The insulating layer 1 is composed of a cover film or a coating layer of insulating resin. The covering film is made of engineering plastics. For example, polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, polyimide, polyimide amide, polyetherimide, polyphenylene sulfide (PPS), polynaphthylene glycol Diol ester (PEN) and so on. When heat resistance is not required, inexpensive polyester film is preferable, when flame retardancy is required, polyphenylene sulfide film is more preferable, and when heat resistance is more required, polyimide film is more preferable. In the case of insulating resin, it is sufficient as long as it is a resin having insulating properties, and examples thereof include thermosetting resin and ultraviolet curable resin. Examples of thermosetting resins include phenol resins, acrylic resins, epoxy resins, melamine resins, silicone resins, and acrylic modified silicone resins. Examples of the ultraviolet curable resin include epoxy acrylate resin, polyester acrylate resin, and these methacrylate modified products. In addition, the curing form may be heat curing, ultraviolet curing, electron beam curing, etc., as long as it is cured.

The method of adjusting the surface roughness of the insulating layer 1 includes: sandblasting in which the surface of the insulating layer 1 itself is made thick with particles such as sand, and coating the surface of the insulating layer 1 with synthetic resin dispersed and mixed with fine particles. A chemical surface roughening method for providing unevenness, a stirring mixing method in which fine particles are mixed in the resin material itself before curing to harden to form the insulating layer 1, an etching method using chemicals such as acid or alkaline chemicals, and a plasma etching method.

The surface of the metal layer 2 opposite to the insulating layer has a bellows structure with an arithmetic average thickness of 0.5 to 5.0 μm. The metal material forming the metal layer 2 may include nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these materials. The metal material and thickness should correspond to the The required electromagnetic wave shielding characteristics and repeated bending and sliding resistance may be appropriately selected, and the thickness may be set to a thickness of about 0.1 μm to 8 μm. In addition, methods for forming the metal layer 2 include electrolytic plating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, CVD, MOCVD, and the like.

In addition, although not shown in the figure, a release layer and a separation film may be sequentially formed on the outside of the insulating layer 1. In addition, an adhesive layer may be formed outside the metal layer 2. With this, after the printed wiring board is attached via the adhesive layer, the mask film 10 for the printed wiring board can be heated and pressurized with a pressing machine to be bonded together, and after the bonding, it is peeled off together with the release layer Separate the film underneath to obtain a shielded printed wiring board.

Here, the adhesive layer can use thermoplastic resins such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, acrylic, etc., or phenol , Epoxy, urethane, melamine, alkyd and other thermosetting resins. When heat resistance is not particularly required, it is best to use a polyester-based thermoplastic resin that is not subject to storage conditions. When heat resistance or better flexibility is required, it is best to have high reliability after forming the shielding layer. The epoxy-based thermosetting resin. In either case, it is of course preferable that the exudation (resin flow) during hot pressing is small.

In addition, the adhesive layer is preferably composed of the above-mentioned resin containing a conductive filler. In addition to being used as an adhesive layer, it can also be used as a layer with electromagnetic wave shielding effect. Conductive fillers can use silver-covered copper fillers coated with silver plating on carbon, silver, copper, nickel, aluminum, and copper powder, and fillers coated with metal plating on resin balls or glass beads or the like A mixture of other fillers. Because of the high price of silver, the lack of reliability of heat resistance of copper, the lack of reliability of aluminum, and the difficulty of soldering to obtain sufficient conductivity, it is better to use a silver-covered copper filler that is cheaper, has good conductivity, and is highly reliable. Or nickel.

The blending ratio of conductive fillers such as metal fillers to adhesive resins is also affected by the shape of the fillers, but when silver-covered copper fillers are used, it is more preferable for 100 parts by weight of the adhesive resin It is 10 to 400 parts by weight, more preferably 20 to 150 parts by weight. If it exceeds 400 parts by weight, the adhesiveness to the ground circuit (copper foil) will decrease, and the flexibility of the printed wiring board or the like will deteriorate. Furthermore, if it is less than 10 parts by weight, the conductivity will be significantly reduced. In addition, in the case of a nickel filler, it is preferably 40 to 400 parts by weight, and more preferably 100 to 350 parts by weight for 100 parts by weight of the adhesive resin. If it exceeds 400 parts by weight, the adhesiveness to the ground circuit (copper foil) will decrease, and the flexibility of the shielded FPC etc. will deteriorate. Furthermore, if it is less than 40 parts by weight, the conductivity will be significantly reduced. The shape of the metal filler may be any of a spherical shape, a needle shape, a fiber shape, a flake shape, and a resin shape. In addition, the above-mentioned conductive filler is preferably a low melting point metal.

According to this embodiment, since the metal layer 2 has a bellows structure with high bendability, it is possible to provide a method that is not easy for repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). The shielding film 10 for a printed wiring board where the destruction of the metal layer 2 occurs. Therefore, it is possible to provide a shielding film for a printed wiring board whose electromagnetic wave shielding characteristics are not easily reduced. In addition, when it is attached to a printed wiring board for use, the printed wiring board can be protected, and even if the printed wiring board is repeatedly bent and slid, the electromagnetic wave shielding characteristics can be maintained.

<Second Embodiment>

Next, a mask film for a printed wiring board according to a second embodiment of the present invention will be described. Fig. 2 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a second embodiment of the present invention. In addition, the parts that are the same as the reference numerals 1 and 2 of the first embodiment are given the reference numerals 11 and 12 in order, and the description thereof may be omitted.

The shielding film 20 for a printed wiring board of this embodiment is a point where a metal layer 13 (second metal layer) having a bellows structure is provided on the surface of the metal layer 12 (first metal layer) opposite to the insulating layer 11 The shape is different.

The metal layer 13 is any material of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these materials, although a material different from the metal layer 12 is used. It is formed, but the metal material and thickness may be appropriately selected in accordance with the required electromagnetic wave shielding characteristics and repeated bending and sliding resistance. In addition, the thickness should just be about 0.1 μm to 8 μm. In addition, methods for forming the metal layer 13 include electrolytic plating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, CVD, MOCVD, and the like. In addition, the surface of the metal layer 13 opposite to the insulating layer has a bellows structure with an arithmetic average thickness of 0.5 to 5.0 μm. Here, as for a modified example, when the metal layer 13 is made of a relatively flexible metal material such as tin, the surface on the outer side may not have a bellows structure.

In addition, although not shown, a release layer and a separation film may be sequentially formed on the outer side of the insulating layer 11. In addition, the same adhesive layer as in the first embodiment may be formed on the outside of the metal layer 13. With this, after the printed wiring board is attached via the adhesive layer, the masking film 20 for the printed wiring board can be heated and pressurized with a pressing machine to be bonded together, and after the bonding, it is peeled off together with the release layer. Separate the film underneath to obtain a shielded printed wiring board.

According to this embodiment, the same effect as that of the first embodiment can be exhibited. In addition, the metal layer 13 can achieve an anti-corrosion effect on the metal layer 12. In addition, when the printed wiring board is attached and used by pressure pressing at a predetermined temperature (for example, 150° C.) or higher, an intermetallic compound may be formed between the metal layer 12 and the metal layer 13. As a result, when the printed wiring board is attached and used by pressing and pressing at a predetermined temperature or higher, the strength will increase, so it can provide a method for repeating from a large bending radius to a small bending radius (1.0mm). A shielding film for printed wiring boards that is less likely to cause damage to the metal layer in terms of bending and sliding.

<The third embodiment>

Next, a mask film for a printed wiring board according to a third embodiment of the present invention will be described. Fig. 3 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a third embodiment of the present invention.

The shielding film 30 for a printed wiring board shown in FIG. 3 is provided with the metal layer 22 formed by depositing one or more types of scaly metal particles on the substantially flat surface of the insulating layer 21.

The metal layer 22 is formed by stacking a large number of scaly metal particles as shown in the schematic diagram of FIG. 4. The average particle diameter of the scaly metal particles is 1 μm-100 μm, and the thickness is 0.1 μm-8 μm. However, if the thickness exceeds 8 μm, because the metal layer 22 is too thick, the film is too thick, which is not ideal. In addition, the material of the scaly metal particles may include nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these, but it can meet the requirements. The electromagnetic wave shielding characteristics and repeated bending and sliding resistance are suitable for selecting one or more materials. In addition, in the metal layer where the scaly metal particles are deposited, the pressure under heating at a predetermined temperature or higher can form gaps between the scaly metal particles and also generate intermetallic bonding, which can become an electrical connection.的层。 The layer. In addition, the metal layer 22 at this time is adjusted in advance so that when the shielding film containing the metal layer 22 is attached to a printed wiring board by pressure at a predetermined temperature (for example, 150°C) or higher, it can be formed to be 0.1μm~ Thickness like 8μm.

In addition, although not shown, a release layer and a separation film may be sequentially formed on the outside of the insulating layer 21. In addition, the same adhesive layer as in the first embodiment may be formed outside the metal layer 22. With this, after the printed wiring board is attached via the adhesive layer, the masking film 30 for the printed wiring board can be heated and pressurized with a pressing machine to be bonded together, and after the bonding, it is peeled off together with the release layer. Separate the film underneath to obtain a shielded printed wiring board. At this time, especially by heating and pressing a part of the adhesive layer in the gap formed between the scaly metal particles, the strength and flexibility of the metal layer can be improved.

According to the present embodiment, when the printed wiring board is attached by pressing and pressing at a predetermined temperature (for example, 150°C) or higher, a gap portion can be formed between the scaly metal particles and an intermetallic bond can also be produced. The metal layer that forms the electrical connection can therefore become a more flexible conductive layer. Therefore, when used in a printed wiring board as described above, it is possible to provide a printed wiring that is less likely to cause damage to the metal layer for repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). Shielding film for board.

<Fourth Embodiment>

Next, a mask film for a printed wiring board according to a fourth embodiment of the present invention will be described. Fig. 5 is a schematic cross-sectional view of a shielding film for a printed wiring board according to a fourth embodiment of the present invention.

The shielding film 40 for a printed wiring board of this embodiment has a metal layer 32 (a first metal layer) and a metal layer 33 (a second metal layer) in this order on the substantially flat surface of the insulating layer 31.

The metal layer 33 is any material of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these materials, although a material different from the metal layer 32 is used. It is formed, but the metal material and thickness may be appropriately selected in accordance with the required electromagnetic wave shielding characteristics and repeated bending and sliding resistance. In addition, the thickness of the metal layers 32 and 33 may be a thickness of about 0.1 μm to 8 μm. In addition, methods for forming the metal layers 32 and 33 include electrolytic plating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, CVD, MOCVD, and the like.

In addition, although not shown in the figure, a release layer and a separation film may be sequentially formed on the outer side of the insulating layer 31. In addition, the same adhesive layer as in the first embodiment may be formed on the outside of the metal layer 32. With this, after the printed wiring board is attached via the adhesive layer, the masking film 40 for the printed wiring board can be heated and pressurized with a pressing machine to be joined together, and after the joining, it is peeled off together with the release layer. Separate the film underneath to obtain a shielded printed wiring board.

According to this embodiment, the metal layer 33 can achieve an anti-corrosion effect on the metal layer 32. In addition, when the printed wiring board is attached and used by pressure pressing at a predetermined temperature (for example, 150° C.) or higher, an intermetallic compound (not shown) may be formed between the metal layer 32 and the metal layer 33. As a result, when the printed wiring board is attached and used by pressing and pressing at a predetermined temperature or higher, the strength will increase, so it can provide a method for repeating from a large bending radius to a small bending radius (1.0mm). A shielding film for printed wiring boards that is less likely to cause damage to the metal layer in terms of bending and sliding.

<Fifth Embodiment>

Next, the printed wiring board according to the fifth embodiment of the present invention will be described. Fig. 6 is a schematic cross-sectional view showing steps in a manufacturing method of a printed wiring board according to a fifth embodiment of the present invention. Fig. 7 is a shielding film body for a printed wiring board according to a fifth embodiment. In addition, the parts that are the same as the symbols 1, 2, and 10 of the first embodiment are given the symbols 41, 42, and 50 in this order, and the description thereof may be omitted.

The printed wiring board 100 of this embodiment, as shown in FIG. 6(c), has the same shielding film 50 for a printed wiring board and the base film 46 of the first embodiment connected by an adhesive layer 47. The base film 46 is provided with: a base film 43 and a printed circuit 44 (signal circuit 44a and ground circuit 44b) formed on the base film 43, and insulation formed on the printed circuit 44 except for at least a part (non-insulating portion) 44c膜45。 Film 45.

Both the base film 43 and the insulating film 45 are made of engineering plastics. For example, resins such as polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, polyimide, polyimide, polyetherimide, and polyphenylene sulfide (PPS) can be mentioned. When heat resistance is not required, it is preferably an inexpensive polyester film, when flame retardancy is required, a polyphenylene sulfide film is more preferable, and when heat resistance is more required, a polyimide film is more preferable.

Here, the bonding of the base film 43 and the printed circuit 44 may be performed by an adhesive, or the adhesive may not be used, and the so-called non-adhesive type copper laminate laminate may be joined together. In addition, the insulating film 45 can be formed by laminating a flexible insulating film using an adhesive or by a series of methods such as coating, drying, exposure, development, and heat treatment of photosensitive insulating resin. In addition, the base film 46 can be suitably used: a single-sided printed wiring board having a printed circuit on only one side of the base film, a double-sided printed wiring board having printed circuits on both sides of the base film, and this printed wiring board is Multi-layer laminated printed wiring boards, "FLEXBOARD" (registered trademark) with a multi-layer component mounting part and cable part, or a stretchable rigid substrate with rigid members constituting the multilayer part, or a tape-and-reel chip carrier package (TCP: Tape-Carrier Package) TAB tape, etc. are implemented.

Adhesive layer 47 is a thermoplastic resin such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, acrylic, etc., as an adhesive resin, or It is composed of thermosetting resins such as phenol, epoxy, urethane, melamine, alkyd, etc. In addition, conductive fillers in which metals, carbon, etc. are mixed with these adhesive resins can be used to provide conductive adhesives with conductivity. In addition, it is also possible to reduce the amount of conductive filler and the like to form an anisotropic conductive layer. When heat resistance is not particularly required, it is best to use a polyester-based thermoplastic resin that is not subject to storage conditions, etc., and when heat resistance or better flexibility is required, it is best to provide reliability after the shielding layer is formed. High epoxy-based thermosetting resin. In either case, it is of course preferable that the exudation (resin flow) during hot pressing is small.

Conductive fillers can use silver-covered copper fillers coated with silver plating on carbon, silver, copper, nickel, aluminum, and copper powder, and fillers coated with metal plating on resin balls or glass beads or the like A mixture of other fillers. Because of the high price of silver, the lack of reliability of heat resistance of copper, the lack of reliability of aluminum, and the difficulty of soldering to obtain sufficient conductivity, it is better to use a silver-covered copper filler that is cheaper, has good conductivity, and is highly reliable. Or nickel.

The blending ratio of the conductive filler to the adhesive resin is also affected by the shape of the filler, but when the copper filler is covered with silver, it is preferably 10 to 400 weight parts for 100 parts by weight of the adhesive resin Parts, more desirably 20 to 150 parts by weight. If it exceeds 400 parts by weight, the adhesiveness to the ground circuit (copper foil) 44b will decrease, and the flexibility of the printed wiring board 100 and the like will deteriorate. Furthermore, if it is less than 10 parts by weight, the conductivity will be significantly reduced. In addition, in the case of a nickel filler, it is preferably 40 to 400 parts by weight, and more preferably 100 to 350 parts by weight for 100 parts by weight of the adhesive resin. If it exceeds 400 parts by weight, the adhesiveness to the ground circuit (copper foil) 44b decreases, and the flexibility of the printed wiring board 100 deteriorates. Furthermore, if it is less than 40 parts by weight, the conductivity will be significantly reduced. The shape of the conductive filler such as a metal filler may be one of spherical, needle-shaped, fibrous, flake-shaped, and resin-shaped.

The thickness of the adhesive layer 47 is, as described above, when conductive fillers such as metal fillers are mixed, only the part of the fillers becomes thicker, and becomes about 20±5 μm. In addition, when no conductive filler is mixed, it is 1 μm to 10 μm. Therefore, the overall thickness of the shielding layer (metal layer 42 and adhesive layer 47) can be made thin, and the printed wiring board 100 can be made thin.

Next, the shielding film body used in the manufacture of the printed wiring board of the fifth embodiment of the present invention will be explained using FIG. 7. The shielding film body of FIG. 7 has: the same as that of the first embodiment, the shielding film 50 for a printed wiring board, and the insulating layer 41 (opposite to the metal layer 42) of the shielding film 50 for the printed wiring board formed in this order. The release layer 48b, the separation film 48a, and the aforementioned adhesive layer 47 formed on the surface of the metal layer 42 (opposite to the insulating layer 41). In addition, when the adhesive layer 47 is a conductive adhesive layer, it forms a shielding layer together with the metal layer 42.

The separation film 48a uses the same engineering plastic as the base film 43, the insulating film 45, and the insulating layer 41. However, since it is removed during the manufacturing process, it is preferably an inexpensive polyester film.

The release layer 48b is not particularly limited as long as it has releasability to the insulating layer 41. For example, a silicon-coated PET film or the like can be used.

Next, the manufacturing method of the printed wiring board concerning the 5th Embodiment of this invention is demonstrated. First, the above-mentioned shielding film body of FIG. 7 is placed on the base film 46, and the pressing machine 49 (49a, 49b) is used to heat and press the same. A part of the adhesive layer 47 softened by heating is pressurized to flow into the insulation removal part 45a like an arrow (see FIG. 6(a)).

In this way, after a part of the adhesive layer 47 is sufficiently bonded to the non-insulating portion 44c of the ground circuit 44b and the insulating film 45, the formed printed wiring board 10 is taken out from the press 49, and if the shielding film for the printed wiring board The separation film 48a of 50 is peeled f together with the release layer 48b (refer to FIG. 6(b)), and the printed wiring board 100 (refer to FIG. 6(c)) can be obtained.

According to this embodiment, the effect of the shielding film for printed wiring boards of 1st Embodiment can be exhibited.

In particular, it is possible to provide a printed wiring board 100 that is physically protected even for repeated bending and sliding from a large bending radius to a small bending radius (1.0 mm), the electromagnetic wave shielding characteristics are not reduced.

<Sixth Embodiment>

Next, the printed wiring board according to the sixth embodiment of the present invention will be described. Fig. 8 is a schematic cross-sectional view of a printed wiring board according to a sixth embodiment of the present invention. In addition, the parts that are the same as the symbols 11, 12, 13, and 20 in the second embodiment are given the symbols 51, 52, 53, and 50 in this order, and the description thereof may be omitted. In addition, the symbols 54 to 58 are assigned to the parts that are the same as the symbols 43 to 47 in the fifth embodiment in order, and the description thereof may be omitted.

The printed wiring board 101 of the present embodiment is different from the fifth embodiment in that it replaces the shielding film 50 for a printed wiring board and includes the shielding film 60 for a printed wiring board which is the same as that of the second embodiment. In addition, the printed wiring board 101 can be manufactured using the same manufacturing method as that of the fifth embodiment.

According to this embodiment, the same effect as the printed wiring board of the fifth embodiment can be exhibited. In addition, as a modified example, instead of the shielding film 60 for a printed wiring board, the shielding film for a printed wiring board of the third or fourth embodiment may be attached to the same type of printed wiring board as this embodiment.

<The seventh embodiment>

Next, the printed wiring board according to the seventh embodiment of the present invention will be described. Fig. 9 is a schematic cross-sectional view of a printed wiring board according to a seventh embodiment of the present invention. In addition, the symbols 61a, 62a, 70a (61b, 62b, 70b) (61b, 62b, 70b) are given to the parts that are the same as the symbols 21, 22, and 30 of the third embodiment in this order, and the description thereof may be omitted. In addition, the symbols 64 to 67 are assigned to the parts that are the same as the symbols 44 to 47 in the fifth embodiment in order, and the description thereof may be omitted.

The printed wiring board 102 of this embodiment is a point where (1) the same masking films 70a and 70b for printed wiring boards as in the third embodiment are attached to both sides of the base film 66 via the adhesive layers 67 and 68, ( 2) Insulation removal parts 65a and insulation removal parts 63a are provided on the upper and lower insulation film 65 and base film 63 sides of the ground circuit 64b. In the non-insulation part 64c on the upper and lower surfaces of the ground circuit 64b, the respective adhesive layers 67, 68 and The point at which the ground circuit 64b is connected is different from the fifth embodiment. In addition, the adhesive layer 68 uses the same material as the adhesive layer 67. In addition, the printed wiring board 102 can be manufactured using the same manufacturing method as that of the fifth embodiment.

According to this embodiment, it is possible to provide a printed wiring board 102 that can exhibit the same effect as the printed wiring board 100 of the fifth embodiment on both sides of the base film 66.

In addition, in its modification, it is possible to replace the shielding films 70a and 70b for printed wiring boards, and to attach the shielding films for printed wiring boards of the first, second, or fourth embodiments in the same manner as this embodiment. The printed wiring board. Moreover, you may use the shielding film for each printed wiring board of 1st-4th embodiment suitably in combination.

<Eighth Embodiment>

Next, the printed wiring board according to the eighth embodiment of the present invention will be explained. Fig. 10 is a schematic cross-sectional view of a printed wiring board according to an eighth embodiment of the present invention. In addition, the symbols 71a, 72a, 73a, and 80a (71b, 72b, 73b, and 80b) are assigned to the parts that are the same as the symbols 31, 32, 33, and 40 of the fourth embodiment in this order, and the description thereof may be omitted. In addition, the parts that are the same as the symbols 45 to 47 of the fifth embodiment are given the symbols 76 to 78 in order, and the description thereof may be omitted.

The printed wiring board 103 of this embodiment is (1) the points where the same masking films 80a, 80b for printed wiring boards of the fourth embodiment are attached to both sides of the base film 77 via the adhesive layers 78, 79, ( 2) The insulation removal part 76a and the insulation removal part 74a are provided on the upper and lower insulation film 76 and base film 74 sides of the ground circuit 75b, and the ground circuit 75b is provided with a through hole 75d connecting the insulation removal part 76a and the insulation removal part 74a The point at which the adhesive layers 78 and 79 contact at the position 78a in the through hole 75d is different from that of the fifth embodiment. In addition, for the adhesive layer 79, the same material as the adhesive layer 78 is used. In addition, the printed wiring board 103 can be manufactured using the same manufacturing method as that of the fifth embodiment.

According to this embodiment, it is possible to provide a printed wiring board 103 that can exhibit the same effects as the printed wiring board of the fifth embodiment on both sides of the base film 77.

In addition, in its modification, it is possible to replace the shielding films 70a and 70b for printed wiring boards, and to attach the shielding films for printed wiring boards of the first, second, or fourth embodiments in the same manner as this embodiment. The printed wiring board. Moreover, you may use the shielding film for each printed wiring board of 1st-4th embodiment suitably in combination.

<Ninth Embodiment>

Next, the printed wiring board according to the ninth embodiment of the present invention will be described. Fig. 11 is a schematic cross-sectional view of a printed wiring board according to an eighth embodiment of the present invention. In addition, the symbols 81, 82, and 90 are assigned to the parts that are the same as the symbols 1, 2, and 10 in the first embodiment in order, and the description thereof may be omitted. In addition, the symbols 83 to 87 are assigned to the parts that are the same as the symbols 43 to 47 of the fifth embodiment in order, and the description thereof may be omitted.

In the printed wiring board 104 of this embodiment, the shielding film 90 for a printed wiring board is covered on one side of the base film 86 via the adhesive layer 87, and the rectangular ground member 93 is provided in the edge part.

In the ground member 93, an adhesive resin layer 92 is provided on one surface of a rectangular metal foil 91 having a width W. The larger the width W of the ground member 93 is, the lower the ground impedance is, which is more desirable, but it is better to appropriately select it from the viewpoint of operability and economy. In this example, among the width W, the width W1 is exposed, and the width W2 is adjacent to the adhesive layer 87. As long as the exposed portion of the width W1 is connected to a nearby grounding portion with an appropriate conductive member, it can be grounded reliably. In addition, if the next step is performed reliably, the width W2 may be further reduced. Moreover, the length of the grounding member 93 is for ease of processing in this example, and is made to match the width of the shielding film 90 or the base film 86, but it is also shorter or longer as long as it is connected to the conductive adhesive layer 92 The part and the one that can be exposed and connected to the nearby grounding part is sufficient.

In the same way, the shape of the grounding member 93 is not limited to a rectangular shape, as long as one part is connected to the adhesive layer 87 and the other part can be connected to a nearby grounding part.

In addition, the arrangement position is not necessarily limited to the end of the printed wiring board 104, and may be a position 93a other than the end as shown by the imaginary line in FIG. 11(a). However, in this case, in order to be able to connect to a nearby ground portion, the ground member 93a is formed to protrude from the shielding film 90 to the side and is exposed. The extension lengths L1 and L2 to both sides may be the length that can be connected to the grounding part near the frame of the machine, etc., and the extension part may have only one end. In a manner that the surface of the metal layer 82 can be connected to the grounding portion, the connection is made by screw fixing or soldering.

The material of the metal foil 91 of the ground member 93 is preferably a copper foil from the viewpoints of conductivity, flexibility, economy, etc., but it is not limited to this. In addition, instead of metal foil, conductive resin may be used, but from the point of conductivity, metal foil is more preferable.

In addition, the adhesive resin layer 92 preferably uses thermoplastic resins such as polystyrene-based, vinyl acetate-based, polyester-based, polyethylene-based, polypropylene-based, polyamide-based, rubber-based, and acrylic-based resins, or Thermosetting resins such as phenol, epoxy, urethane, melamine, polyimide, alkyd, etc. are used for the metal foil, adhesive resin layer or base film 86 constituting the ground member 93 The insulating film 85 has better adhesiveness. In addition, when the ground member 93 is provided at a position other than the end portion and covered with a shielding layer (the metal layer 82, but when the adhesive layer 87 is a conductive adhesive layer, the adhesive layer 87 is also included), it is also It can be composed of only metal foil or metal wire.

As described above, the shielding layer of the shielding film 90 (the metal layer 82, but when the adhesive layer 87 is a conductive adhesive layer, the adhesive layer 87 is also included) is grounded by the grounding member 93, so it is not necessary to provide a wide The ground wire is used as a part of the printed circuit, which can increase the wiring density of the signal wire. In addition, the ground impedance of the ground member 93 is easier to reduce compared to the ground impedance of the ground line of the conventional printed wiring board, and therefore the electromagnetic wave shielding effect of the shielding layer also increases.

In addition, as in the past, a wide ground wire is provided to connect the shielding layer (the metal layer 82, but when the adhesive layer 87 is a conductive adhesive layer, the adhesive layer 87 is also included) is provided with a grounding member in the printed wiring board Those are of course included in the present invention. In this case, due to the additive effect of the substrate grounding of the broad grounding wire and the frame grounding of the grounding member, the electromagnetic wave shielding effect is better and more stable.

The front end of the base film 86 is exposed only by the width t1, and the printed circuit 84 is exposed. In addition, in this example, the ground member 93 can be connected at one end in the width direction from the end of the insulating film 85 by a width t2, and the width t2 ensures insulation resistance with the signal line.

In addition, the ground member may have various forms other than the form shown in FIG. 11. For example, it may be that the grounding member is a metal foil made of copper, silver, aluminum, etc., and a plurality of conductive bumps protruding from one side of the metal foil will penetrate the cover film to connect to the shielding layer, and the exposed metal foil will be It is connected to the ground near it.

In addition, it can also be: the grounding member is a plurality of protrusions formed on one side, a metal plate composed of copper, silver, aluminum, etc., the protrusions penetrate the cover film to connect to the shielding layer, and the exposed metal plate is connected to The shape of the ground near it.

Alternatively, the grounding member is a metal foil made of copper, silver, aluminum, etc., and a plurality of metal fillers protruding from one side of the metal foil penetrate the cover film to connect to the adhesive layer and the metal layer of the shielding layer , The exposed metal foil will be connected to the ground near it.

Alternatively, the cover film may be removed by using an excimer laser to form a window at a predetermined position of the shielding film, and the window may be connected to one end of the ground member of the conductor via a conductive adhesive mixed with a conductive filler The form. The other end of the grounding member is connected to a nearby grounding part. Or, the grounding part located nearby may be directly connected to the window part without the grounding member.

In addition, in the modification example, instead of the shielding film 90 for a printed wiring board, the shielding film for a printed wiring board of the 2nd to 4th embodiment may be a printed wiring board attached like this embodiment.

[Example]

(Example 1)

First, a shielding film for a printed wiring board having the same structure as the shielding film 10 for a printed wiring board shown in FIG. 1 was produced (for details of the metal layer, refer to Example 1 of Table 1 below). Fig. 13(a) is an SEM photograph showing the shielding film for printed wiring boards produced at this time. In addition, FIG. 13(b) is a schematic diagram showing the imaging direction of the SEM photograph of FIG. 13(a). After the shielding film for printed wiring boards having such a metal layer with a bellows structure is produced, the shielding film for printed wiring boards is bonded to the printed wiring board with a press machine through an adhesive to produce a shielded film Printed wiring board (width 10mm, length 170mm). Here, the insulating layer of the shielding film for a printed wiring board of this embodiment is a polyimide resin layer with a thickness of 12.5 μm. The adhesive layer is made of epoxy resin with a thickness of 17 μm. The printed wiring board produced in this manner was used as a sample of Example 1.

(Example 2)

Next, a shielding film for a printed wiring board having the same structure as the shielding film 10 for a printed wiring board shown in FIG. 1 was produced (for details of the metal layer, refer to Example 2 of Table 1 below). Then, this shielding film for a printed wiring board was bonded to a printed wiring board with a press machine via an adhesive, while heating and pressing, to produce a printed wiring board with a shield (width 10 mm, length 170 mm). In addition, the insulating layer and the adhesive were the same as in Example 1. The printed wiring board produced in this manner was used as a sample of Example 2.

(Example 3)

Next, a shielding film for a printed wiring board having the same structure as the shielding film 10 for a printed wiring board shown in FIG. 1 was produced (for details of the metal layer, refer to Example 3 of Table 1 below). Then, this shielding film for a printed wiring board was bonded to a printed wiring board with a press machine via an adhesive, while heating and pressing, to produce a printed wiring board with a shield (width 10 mm, length 170 mm). In addition, the insulating layer and the adhesive were the same as in Example 1. The printed wiring board produced in this manner was used as a sample of Example 3.

(Comparative example 1)

In place of the two metal layers of Example 1, a shielding film for printed wiring boards with a one-layer silver film layer with a thickness of 0.1 μm was produced. Then, this shielding film for a printed wiring board was bonded to a printed wiring board with a press machine via an adhesive, while heating and pressing, to produce a printed wiring board with a shield (width 10 mm, length 170 mm). In addition, the insulating layer and the adhesive were the same as in Example 1. The printed wiring board produced in this manner was used as a sample of Comparative Example 1.

(Comparative example 2)

In place of the two metal layers of Example 1, a shielding film for printed wiring boards in which a silver paste layer with a thickness of 20 μm was formed was produced. Then, this shielding film for a printed wiring board was bonded to a printed wiring board with a press machine via an adhesive, while heating and pressing, to produce a printed wiring board with a shield (width 10 mm, length 170 mm). In addition, the insulating layer and the adhesive were the same as in Example 1. The printed wiring board produced in this manner was used as a sample of Comparative Example 2.

〔Bending resistance test〕

According to the IPC standard, as shown in FIG. 12, a shielded printed wiring board 111 (any of the samples of the above-mentioned Example 1 and Comparative Examples 1 and 2) is set in curvature between the fixed plate 121 and the sliding plate 122 It is installed by bending into a U-shape in the state of 1.0mm. In a test environment of 23°C, it is verified that the sliding plate 122 is slid up and down under the conditions of a stroke of 30mm and a sliding speed of 100 times/min. The resistance of the metal layer of the shielding film (maintenance of electromagnetic shielding) and whether it can protect the printed wiring board. In addition, the printed circuit of each printed wiring board of the samples of the above-mentioned Example 1 and Comparative Examples 1 and 2 used 6 lines, a line width of 0.12 mm, and a space width of 0.1 mm. In addition, the resistance of the metal layer of the shielding film for printed wiring boards (maintenance of electromagnetic shielding properties) and whether the printed wiring board can be protected was verified by measuring the energization amount of the metal layer or printed circuit of each sample. The verification results are shown in Table 1 below.

It can be seen from Table 1 that the samples of Examples 1 to 3 are resistant to the metal layer and can protect the printed wiring board. On the other hand, it can be seen from Comparative Example 1 that although the printed wiring board can be protected, the electromagnetic shielding properties of the silver thin film layer cannot be maintained, and the current flow is reduced. In addition, it can be seen from Comparative Example 2 that although the electromagnetic shielding property of the silver paste layer can be maintained, the printed wiring board (disconnection) cannot be protected.

In addition, the present invention can be changed in design without departing from the scope of the patent application, and is not limited to the above-mentioned embodiments or examples. For example, in the above-mentioned embodiment, although the metal layer has two layers, the metal layer may have three or more layers.

In addition, in each metal layer of the above-mentioned embodiment, a porous one having plural pores or voids may be used. In the case of a porous metal layer with plural pores, the diameter of the pores is 0.1 μm to 10 μm, and in the case of a porous metal layer with plural pores, the size of the pores is 0.1 μm to 10 μm, and the porosity is 1 to 50%. In addition, if the porosity is less than 1%, it is almost impossible to have the effect described later, and if it exceeds 50%, the conductivity will be considerably reduced. In addition, the metal layer at this time is adjusted to a thickness of 0.1 μm to 8 μm when the shielding film containing the metal layer is attached to a printed wiring board by pressing at a predetermined temperature (for example, 150°C) or higher. Such thickness. In addition, the use of plural metal layers is also the same as in the second or fourth embodiment. When the metal layer 12 is attached to the printed wiring board by pressing at a predetermined temperature (for example, 150°C) or higher, An intermetallic compound is formed between the metal layers 13. With this, when the printed wiring board is pressed and pressed for attaching use, a part of the conductive adhesive layer will be filled in the gaps of the holes of the metal layer, which can improve the strength and flexibility of the metal layer. Therefore, it is possible to provide a shielding film for printed wiring boards that is less likely to cause damage to the metal layer and the film is attached to repeated bending and sliding from a large bending radius to a small bending radius (1.0mm). Printed wiring board.

Moreover, the shielding film for printed wiring boards, such as each layer of each embodiment of the shielding film for printed wiring boards, may be combined suitably. In addition, in the shielding film for a printed wiring board of each embodiment, although the metal layer is provided only on one side of the insulating layer, it may be provided on both sides of the insulating layer.

In addition, the shielding film for a printed wiring board of the present invention can be used in FPC, COF (Chip on Flex), RF (Retractable Printed Board), multilayer flexible substrate, rigid substrate, etc. It is not limited to these.

1‧‧‧Insulation layer

2‧‧‧Metal layer

10‧‧‧Shielding film for printed wiring board

Claims (5)

A shielding film for a printed wiring board, characterized by comprising: a first metal layer formed on one surface of an insulating layer; and a second metal layer formed on the surface of the first metal layer opposite to the insulating layer; 1 The metal layer and the above-mentioned second metal layer are layers using any material of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing any one or more of these materials, and The second metal layer is composed of materials of different types, and the second metal layer is a porous layer having many pores. For example, the shielding film for printed wiring boards of the first item of the scope of patent application, wherein a conductive adhesive layer is formed on the surface of the second metal layer opposite to the insulating layer. For example, the shielding film for printed wiring boards of the first or second patent application, wherein the first metal layer is a porous layer with a plurality of holes. For example, the shielding film for printed wiring board of the first or second patent application, wherein the first metal layer is a layer formed of scaly metal particles of one or more materials. For example, the shielding film for printed wiring boards of the first or second patent application, wherein the first metal layer and the second metal layer are formed between the first metal layer and the second metal layer. The way the compound is heated and pressurized.

Images