TWI522236B - Electromagnetic wave shielding material and electromagnetic wave shielding material manufacturing method - Google Patents

Description

Electromagnetic wave shielding material and electromagnetic wave shielding material manufacturing method

The present invention relates to a case where a defective portion of a copper foil composite which is an electromagnetic wave shielding material is removed during processing of a shielding material, or a case where a length of a copper foil composite is insufficient, and the like, and the present invention relates to an electromagnetic wave shielding material and electromagnetic wave shielding. In the method of producing a material, a copper foil composite in which a copper foil and a resin film are laminated is joined in a plurality of directions in the longitudinal direction.

In the electromagnetic wave shielding material, a copper foil composite in which a copper foil and a resin film are laminated can be used as long as the shielding property is excellent and corrosion resistance can be improved by performing Sn plating. The method of attaching the copper foil composite as a shielding material to a shield such as a cable, or a method of longitudinally winding (spiral) the shielding material on the shielded body or longitudinally coating (so that the shielding material is along the cable) The method of winding in the axial direction and the longitudinal direction of the copper foil composite is wound around the axial direction when the outer periphery of the shield is wound.

In the case where a copper foil is used for the shielding material, a copper foil is laminated with a resin film such as PET in order to impart insulation or to facilitate handling (Patent Document 1). Further, such a copper foil laminate is usually combined with a drain wire, and the copper foil and the drain wire are placed on the cable side to be electrically connected, and the PET film is positioned on the outer side, and the outer side of the PET film is covered with a sheath.

Patent Document 1: Japanese Patent Laid-Open No. Hei 7-290449

However, when the shield processing is performed on the production line, the coil-shaped copper foil composite is wound up and wrapped on the shielded body, so that the two are inserted into the mold and the like, and when the coil length is insufficient, the coil may be insufficient. A plurality of copper foil composites are joined in the longitudinal direction. The bonding is performed by tape-bonding a portion of the copper foil composite that overlaps in the longitudinal direction or abutting portions, or fixing it with an adhesive such as an acrylic resin or an adhesive.

However, when the shielded copper foil composite is used for the shield processing, the shield structure such as the sheath of the electric wire is inflated or recessed in the vicinity of the joint portion.

Therefore, an object of the present invention is to provide an electromagnetic wave shielding material and a method for producing an electromagnetic wave shielding material, which are shielded by using an electromagnetic wave shielding material in which a plurality of copper foil composites are joined in the longitudinal direction. It will prevent the deformation of the shape of the shield structure.

The inventors of the present invention have found that the defect of the outer shape of the shield structure (hereinafter, referred to as "concave defect" as appropriate) is caused by a decrease in the strength of the joint when the temperature of the joint portion between the copper foil composites rises, and the shield structure The problem of the expansion of the shape outside the body (hereinafter referred to as "expansion failure" as appropriate) is caused by the fact that the rigidity of the joint portion between the copper foil composites is increased and the thickness is increased, and the present invention has been completed.

In other words, the electromagnetic wave shielding material of the present invention is an electromagnetic wave shielding material in which a plurality of copper foil composites are joined in the longitudinal direction, and the copper foil composite copper foil and the resin film are laminated, and the copper foil composites are mutually The overlapping portion is followed by an epoxy-based adhesive, which is epoxy resin and is selected from nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber. A resin which imparts flexibility as a main component of one or more of the group consisting of ethylene propylene rubber, isoprene rubber, urethane rubber, and acryl rubber, and the above-mentioned ring sandwiched between the copper foil composites The length LA of the oxygen-based adhesive in the longitudinal direction is 1 to 6 mm.

The overlapping portions of the copper foil composites are cut out in such a manner that the length in the direction perpendicular to the longitudinal direction is 7 mm, and a rectangular sheet is formed, and one of the rectangular sheets is fixed at one end. At this time, the force P per unit width required to displace the point 5 mm from the fixed end to the deflection amount of 3 mm is preferably 5 N/m ≦ P ≦ 15 N/m.

Further, P × LA ≦ 45 mN is preferable.

Further, the electromagnetic wave shielding material of the present invention is obtained by joining a plurality of electromagnetic wave shielding materials in which a plurality of copper foil composites are joined in the longitudinal direction, and the copper foil composite resin copper foil and the resin film are laminated, and the copper foil composites are mutually The overlapping portion is followed by an epoxy-based adhesive, which is an epoxy resin and is selected from the group consisting of nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, and the like. A softening resin composed of one or more of a group of a pentadiene rubber, an amine ester rubber, and an acrylic rubber is used as a main component, and a bonding strength per unit width of the overlapping portion of the copper foil composites at 150 ° C is 1.5. N/mm or more.

The method for producing an electromagnetic wave shielding material according to the present invention has the steps of: overlapping steps: a plurality of copper foil composites in which a copper foil and a resin film are laminated are stacked in the longitudinal direction; and a bonding step: the copper foil composites are mutually The overlapping portion is sandwiched between a group selected from the group consisting of nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, isoprene rubber, amine ester rubber, and acrylic rubber. One or more types of epoxy-based adhesives of epoxy resins are followed.

According to the present invention, when the electromagnetic wave shielding material obtained by joining a plurality of copper foil composites in the longitudinal direction is shielded, the deformation of the shield structure outside the shape can be prevented.

The electromagnetic wave shielding material of the present invention is obtained by joining a plurality of copper foil composites in which a copper foil and a resin film are laminated in the longitudinal direction. Usually, the longitudinal direction is an axial direction when the electromagnetic wave shielding material is wound around the outer circumference of the shielded body.

<copper foil>

The higher the conductivity (the higher the purity), the higher the shielding performance. Therefore, the composition of the copper foil is preferably higher in purity, and the purity is preferably 99.0% or more, more preferably 99.8% or more. The rolled copper foil which is excellent in flexibility is preferably an electrolytic copper foil.

Further, the thickness of the copper foil is preferably 4 to 20 μm, more preferably 4 to 15 μm. When the thickness is less than 4 μm, the shielding property is lowered, the strength is lowered, and the manufacturability is poor. When the thickness is more than 20 μm, the shielding property is improved, but the rigidity is increased, and it is difficult to coat the shape of the object to be adhered, or rebound after the coating, and a gap is formed at the joint of the shielding material to provide shielding. Deterioration. Further, when the thickness exceeds 20 μm, the quality of the shield material may become heavy. In addition, when the thickness of the copper foil exceeds 15 μm, even if the component of the epoxy-based adhesive or the thermocompression bonding condition in the overlapping portion is adjusted or the LA is shortened, P described later exceeds 15 N/m, or The value of P × LA tends to exceed 45 mN, so the thickness of the copper foil is more preferably 15 μm or less.

<Resin film>

The resin film is not particularly limited, and a PET film can be preferably used. In particular, strength can be improved by using a biaxially stretched film as a PET (polyethylene terephthalate) film. The thickness of the resin film is not particularly limited, but is usually about 7 to 25 μm. When the thickness of the resin film is thinner than 7 μm, there is a case where the production line is easily broken and the manufacturability is inferior. On the other hand, when the thickness of the resin film is thicker than 25 μm, P tends to exceed 15 N/m or P×LA exceeds 45 mN, and therefore the thickness of the resin film is preferably about 12 μm.

As a method of laminating the resin film and the copper foil, an adhesive may be used between the resin film and the copper foil, or the resin film may be thermocompression bonded to the copper foil without using an adhesive. However, from the viewpoint of not applying excess heat to the resin film, it is preferred to use an adhesive.

Further, the overall thickness of the copper foil composite in which the resin film and the copper foil are laminated is preferably about 20 to 40 μm.

<Electromagnetic wave shielding material>

FIG. 1 is a cross-sectional view showing a configuration of an electromagnetic wave shielding material 50 in which a plurality of copper foil composites 10 are joined in the longitudinal direction L.

The copper foil composite 10 is formed by laminating a copper foil 2 of 8 μm thick and a resin film (PET film) of 12 μm thick, and an adhesive layer 3 (3 μm thick) is interposed between the copper foil 2 and the PET film 4. Further, on the surface of the copper foil 2, a Sn-plated layer 9 having a thickness of 1 μm was formed to improve corrosion resistance (salt resistance). Further, a thermoplastic adhesive layer 8 (3 μm thick) is formed on the surface of the PET film 4, and when the copper foil composite 10 (electromagnetic wave shielding material) is wrapped around the outer side of the shielded body and covered with a sheath, The electromagnetic wave shielding material is then brought into contact with the sheath, or the electromagnetic wave shielding material is wrapped around the end portion, and does not have an adhesive force at normal temperature.

In addition, the overlapping portion 50k of the end portions of the two copper foil composites 10 in the longitudinal direction L is joined by an epoxy-based adhesive (layer) 6 to form the electromagnetic wave shielding material 50. In addition, when the length of the epoxy-based adhesive (layer) 6 in the longitudinal direction L is LA, LA is equal to or less than the length of the overlapping portion 50k.

Further, the insulating layer 8 for shielding of one of the copper foil composites 10 is overlapped with the Sn-plated layer 9 of the other copper foil composite 10 so as to face each other.

Further, there is also a case where the Sn-plated layer 9 of each of the copper foil composites 10 is not formed, or the case where the layer 8 is not required. Further, there is a case where neither the Sn-plated layer 9 nor the subsequent layer 8 of each of the copper foil composites 10 is required. In such a case, the respective surfaces of the respective copper foil composites 10 overlap the back surface.

<Shielding processing>

FIG. 2 is a view showing a state in which the copper foil composite 10 (electromagnetic wave shielding material 50) is covered on the shielded body (core wire) 20 and shielded.

In FIG. 2, the longitudinal direction L of the copper foil composite 10 is along the axial direction of the shield 20, and the axial direction at this time is the longitudinal direction L, and the PET of the copper foil composite 10 is used. The film is wound (longitudinally coated) so that the film side faces outward. In addition, the copper foil composite 10 covering the outer periphery of the shielded body 20 is sequentially inserted into the first die 201 and the second die 202 to reduce the diameter, and when the third die 203 is inserted, the copper foil composite 10 is used. When the outer side flows into the molten sheath material (PVC or the like) 30a, the shield structure (shield cable) 100 covered by the sheath 30 on the outer side of the copper foil composite 10 is exposed from the third mold 203.

Here, the overlapping portion 50k of the copper foil composite 10 also passes through the respective molds 201 to 203, but at this time, the outer shield structure 100 is defective in depression.

FIG. 3 is a view showing the appearance of the failure of the shield structure 100 passing through the respective molds 201 to 203. As shown in FIGS. 3(a) and 3(b), a concave portion 10x or an expanded portion 10y is formed in the vicinity of the overlapping portion 50k.

As a result of investigations by the inventors of the present invention, it has been clarified that the concave shape of the outer shape of the shield structure is caused by a decrease in the strength of the joint when the temperature of the joint portion between the copper foil composites rises. In other words, when the respective molds 201 to 203 are held at a temperature of about 180 ° C and the copper foil composite 10 is inserted into the respective molds 201 to 203, the temperature of the copper foil composite rises to about 150 °C. At this time, in the overlapping portion 50k, the bonding strength between the joint portions of the copper foil composites 10 is lowered, and the overlapping portion 50k is shifted in the longitudinal direction (the length LA of the joint portion 50k is shortened), so that a concave deformation occurs.

In addition, the reason why the expansion of the shape outside the shield structure is considered to be poor is as follows. In other words, since the rigidity of the overlapping portion 50k is increased or the thickness is increased, the winding diameter of the shielded body 20 is increased in the overlapping portion 50k. As a result, the overlapping portion 50k is caused to remain when passing through the respective molds 201 to 203, or a step is generated in front of the overlapping portion 50k due to the increase in the winding diameter, and the sheath material 30a adheres in a large amount.

Therefore, the present inventors have found the following ring in order to maintain the bonding strength between the copper foil composites 10 at a temperature in the vicinity of 150 ° C and to maintain the bonding strength, and the thickness is small and the rigidity is low. Oxygen based adhesive.

<epoxy adhesive>

An epoxy-based adhesive containing an epoxy resin and a resin imparting flexibility as a main component is used as an adhesive for the subsequent overlapping portion 50k.

The resin imparting flexibility is preferably selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), and ethylene propylene rubber (EPDM). One or more of a group of isoprene rubber (IR), amine ester rubber (PUR), and acrylic rubber (ACM-ANM).

It is considered that these rubbers are interposed between the cured epoxy skeletons as particles or the like, and absorb the energy at the time of plastic deformation of the adhesive layer to lower the rigidity of the epoxy-based adhesive, thereby imparting flexibility.

From the viewpoint of compatibility with an epoxy resin, a nitrile butadiene rubber (NBR: acrylonitrile-butadiene copolymer) is particularly preferable.

Further, although a large amount of a component containing a softening resin in the epoxy-based adhesive can reduce the value of P or the value of P×LA, there is a tendency that the shear strength is lowered. If the shear strength at 150 ° C is less than 1.5 N/mm, there is a case where the overlap portion 50k is peeled off due to the tension of the production line.

The epoxy resin may, for example, be a bisphenol A epoxy resin, a dicyclopentadiene epoxy resin, a naphthol epoxy resin or a phenol novolak epoxy resin, and any known epoxy resin may be used.

As the hardener, a known hardener for curing an epoxy resin can be used, and for example, various amine-based hardeners can be used.

In addition, the ratio of the epoxy resin to the rubber is not particularly limited, and the rubber is usually used in an amount of about 10 to 400 parts by mass based on 100 parts by mass of the epoxy resin.

An additive such as a filler may be blended in the epoxy-based adhesive as needed. Usually, the amount of the additive other than the epoxy resin and the rubber is preferably less than 10 parts by mass relative to 100 parts by mass of the epoxy-based adhesive. Share.

The epoxy-based adhesive may be applied to the overlapping portion 50k by an adhesive solution obtained by mixing an epoxy resin, the above-mentioned rubber, a curing agent, and other additives as necessary with an organic solvent, or may be carried on the base by the adhesive solution. The form of the adhesive tape on the film is attached to the overlapping portion 50k. Thereafter, the overlapping portion 50k in which the epoxy-based adhesive is interposed is thermocompression bonded to cure the epoxy resin and then proceed.

In addition, when the epoxy-based adhesive is used in the overlapping portion 50k, the adhesion strength to the Sn layer 9 is sufficient, but the adhesion strength to the PET film layer 8 (actually, the barrier layer 8 for shielding) tends to decrease. Further, it has been found that the temperature at the time of thermocompression bonding is preferably 30 ° C or more higher than the Tg (glass transition temperature) of the resin film. Since the Tg of PET is about 110 ° C, it is preferred to make the thermocompression bonding temperature exceed 140 ° C. Further, in the case of thermocompression bonding, it is preferred to perform pre-compression bonding at room temperature first, followed by heating to perform pressure bonding. Further, when thermocompression bonding is performed while gradually increasing from room temperature to a predetermined temperature, shape defects such as wrinkles caused by thermocompression bonding do not occur.

The length LA of the epoxy-based adhesive (layer) 6 sandwiched in the overlapping portion 50k in the longitudinal direction is preferably from 1 to 6 mm. When LA is less than 1 mm, the bonding strength of the overlapping portion 50k is lowered to easily cause the above-described concave defect. On the other hand, when LA exceeds 6 mm, the rigidity becomes high and the expansion failure is likely to occur.

Fig. 3(b) is a schematic view showing the appearance of poor expansion. Although the reason is not clear, it is considered that the hardness of the overlapping portion 50k has an influence.

As shown in Fig. 4, the overlapping portion 50k of the copper foil composite 10 is cut into a rectangular sheet 50s so that the length in the direction perpendicular to the longitudinal direction L becomes 7 mm, and the rectangular sheet 50s is formed. When a short side single end is fixed to the fixed wall 300, the value of P described later is preferably the following. Here, Fig. 4(a) shows a plan view of the rectangular sheet 50s when it is fixed at one end (the upper surface of the rectangular sheet 50s is the direction of the paper surface), and Fig. 4(b) shows the side view (the cut surface of the rectangular sheet 50s is the paper surface). Direction). Further, the length of the short side of the rectangular piece 50s is equal to the length LA of the overlapping portion 50k.

Further, in Fig. 4(b), a downward force is applied as indicated by the arrow from the point where the fixed end 50e of the rectangular piece 50s is inclined toward the free end by 5 mm. At this time, as shown in Fig. 4(c), the force P of the unit width of the rectangular piece 50s required to displace the downward rectangular piece 50s to the deflection amount of 3 mm is preferably 5 N/m ≦ P ≦ 15 N/m.

In the case where P is less than 5 N/m, there is a case where the overlapping portion 50k has a bonding strength of less than 1.5 N/mm at 150 ° C, and a concave defect is likely to occur. On the other hand, when P exceeds 15 N/m, the rigidity of the overlapping portion 50k becomes high, and convexity defects are likely to occur, and even if LA is controlled to 1 to 6 mm, a convex defect occurs.

In addition, when the copper foil or the resin film is thick, P becomes high. Therefore, when the copper foil or the resin film is thickened, the adjustment P is returned by the following method: (1) Improvement of the epoxy-based adhesive (2) The thickness of the epoxy-based adhesive is reduced, and (3) the temperature of the thermo-compression bonding of the epoxy-based adhesive is lowered.

Further, when P × LA ≦ 45 mN, the occurrence of convex defects can be further suppressed. Further, if the rectangular sheet 50s is warped, it is difficult to measure the P described above with high precision. Therefore, it is preferable to use a flat copper foil composite which is wrapped around the shielded body for measurement.

Further, the bonding strength of the overlapping portion 50k at 150 ° C is preferably 1.5 N/mm or more. As described above, since the concave defect is insufficient in the strength of the overlapping portion 50k, the bonding strength, that is, the bonding strength at 150 ° C is 1.5 N/mm or more, whereby the bonding strength can be improved and the concave defect can be prevented. In addition, when the bonding strength at 150 ° C is 2 N/mm or more, the copper foil composite (electromagnetic wave shielding material) is overcoated under the manufacturing conditions for shielding processing by covering the shielded body. The tension can also prevent concave defects and is therefore better. Further, the measurement of the adhesion strength of the overlapping portion 50k is such that the tensile strength of the two copper foil composites 10 including the overlapping portion 50k is pulled apart in the L direction, and therefore, unlike the above P, the package may be wrapped in The copper foil composite (warped in the diameter direction) after being shielded was used for measurement.

The thickness of the epoxy-based adhesive (layer) 6 is preferably 35 μm or less. When the thickness of the epoxy-based adhesive (layer) 6 exceeds 35 μm, there is a case where the overlapping portion 50k is hardened and the expansion failure occurs as in the case of the LA described above. In addition, as long as the adhesion strength of the overlapping portion 50k at 150 ° C is 1.5 N/mm or more and an adhesive (layer) can be formed, the lower limit of the thickness of the epoxy-based adhesive (layer) 6 can be made thinner. . Usually, the lower limit of the thickness of the epoxy-based adhesive (layer) 6 is about 1 to 2 μm, and it is preferably about 6 to 25 μm in terms of ease of work.

Example 1

<Manufacture of Copper Foil Composite>

The copper ingot is hot-rolled, and the oxide is removed by surface cutting, and then cold rolling, annealing, and pickling are repeated until the thickness is 8 μm, and finally, annealing is performed to obtain a copper foil having ensured workability. In order to make the copper foil uniform in the width direction, the tension during cold rolling and the rolling conditions in the width direction of the rolled material are uniform. In order to make the temperature distribution uniform in the width direction in the next annealing, a plurality of heaters are used for temperature control, thereby measuring and controlling the temperature of the copper.

A commercially available biaxially stretched PET film having a thickness of 12 μm was attached to the above copper foil with an adhesive having a thickness of 3 μm. Further, a Sn plating layer of 1 μm was formed on the surface of the copper foil opposite to the surface layer of the PET film to produce a copper foil composite. The copper foil composite was cut into a predetermined strip test piece.

<Manufacture of electromagnetic wave shielding material>

The test piece of the two copper foil composites is overlapped with the Sn-plated layer 9 of the other copper foil composite 10 in a masking layer 8 of one of the copper foil composites 10, and is sandwiched in the overlapping portion 50k. After placing an epoxy adhesive tape (a commercially available tape containing nitrile butadiene rubber (NBR) and epoxy resin), pre-compression bonding was performed at room temperature, and hot pressing was performed at the temperature shown in Table 1. The electromagnetic wave shielding material is manufactured by connecting (pressure is 1 MPa or less). Further, the length LA of the epoxy-based adhesive tape in the longitudinal direction was changed to set the thickness to 25 μm.

The electromagnetic wave shielding materials of Experimental Examples 1 to 5 were prepared by changing the thermocompression bonding temperature and LA.

<Continue strength>

Both ends of the electromagnetic wave shielding material were attached to a predetermined tensile tester, and the adhesion strength of the overlapping portion of the obtained electromagnetic wave shielding material was measured at a temperature of 150 °C. The width of the test piece was set to 11.5 mm.

<With or without concave defects>

The obtained electromagnetic wave shielding material is longitudinally coated on a predetermined core wire, inserted into a predetermined mold, and visually judged whether or not there is a concave defect.

In Comparative Example 1, an electromagnetic wave shielding material was produced in the same manner as in Experimental Example 5 except that the length LA of the epoxy-based adhesive (layer) in the longitudinal direction was 10 mm, and the evaluation was performed in the same manner.

In Comparative Example 2, an electromagnetic wave shielding material was produced in the same manner as in Experimental Example 2 except that an acrylic resin (manufactured by Sumitomo 3M Co., Ltd., trade name: F-9460 PC) was used as an adhesive for the overlapping portion 50k, and the evaluation was carried out in the same manner.

In Comparative Example 3, an electromagnetic wave shielding material was produced in the same manner as in Comparative Example 2 except that the thermocompression bonding temperature was 180° C. and LA was 10 mm, and the evaluation was performed in the same manner.

In the comparative example 4, an electromagnetic wave shielding material which is attached to the opposite side of the two copper foil composites by the tape (manufactured by Teraoka Manufacturing Co., Ltd., trade name: 631S) is attached and fixed in the same manner as described above. Between 9 and the adhesive layer 8, the adhesive 6 was used instead of the overlapping portion 50k, and evaluation was performed in the same manner.

The results obtained are shown in Table 1.

As is clear from Table 1, in the case of each of Experimental Examples 1 to 4, the overlapping portion of the copper foil composites at 150 ° C has an adhesive strength of 1.5 N/mm or more and 18 N/11.5 mm or more, and copper foil is not produced. The outer side of the composite has a concave shape.

On the other hand, in the case of Comparative Example 1 in which the length LA of the epoxy-based adhesive tape in the longitudinal direction exceeded 6 mm, expansion failure occurred outside the electromagnetic shielding material.

In the case of Comparative Examples 2 and 3 in which an acrylic resin was used as an adhesive for the overlapping portion, the adhesion strength at 150 ° C of the overlap portion was less than 1.5 N/mm, resulting in a concave defect on the outer side of the electromagnetic wave shielding material. Further, in the case of Comparative Example 3 in which LA exceeded 6 mm, expansion failure also occurred.

In the case of Comparative Example 4 in which an adhesive was used without using an adhesive in the overlapping portion, the bonding strength at 150 ° C was less than 1.5 N/mm, which caused not only a concave defect on the outer side of the electromagnetic wave shielding material but also a poor expansion. .

Further, in the case of Comparative Examples 2 and 3, since an epoxy-based adhesive layer (layer) was used instead of the epoxy-based adhesive layer in the overlapping portion, LA corresponds to an acrylic adhesive (layer). The length in the side direction. On the other hand, the length of the overlap portion of Comparative Example 4 in the longitudinal direction was 10 mm, but since the adhesive layer was not present in the overlapping portions, only the tape of 25 mm was adhered to both sides of the overlapping portion, so Comparative Example 4 The length of the overlapping portion in the longitudinal direction is not equivalent to the LA of each embodiment.

Example 2

Using the sample of the above Experimental Example 1, the wedge-shaped indenter attached to the tip end of the load cell was pressed into the overlapping portion to a predetermined depth, and the load required for the press-in was measured.

For the purpose of comparison, an electromagnetic wave shielding material was produced in the same manner as in Experimental Example 1 except that the LA of the adhesive of the overlapping portion 50k was 10 mm, and the evaluation was performed in the same manner.

The results obtained are shown in Fig. 5. It is known that in the case of Experimental Example 1 in which LA is set to 3 mm, the indenter is pressed into the overlapping portion with a lower load, and the rigidity of the overlapping portion becomes low (softened). Further, the sample of Experimental Example 1 was longitudinally coated on a predetermined core wire so as to be inserted into a predetermined mold, and as a result, no swelling was caused.

Example 3

An electromagnetic wave shielding material was produced in the same manner as in the first embodiment. The thickness of the copper foil in the electromagnetic wave shielding material, the thickness of the PET film, the thickness of the epoxy-based adhesive layer, and LA were changed as shown in Table 2, respectively. Further, the adhesion strength at 150 ° C and P were measured. The measurement of P was carried out by cutting a rectangular sheet 50s as shown in Fig. 4 .

The results obtained are shown in Table 2.

As is clear from Table 2, in the case of each of Experimental Examples 10 to 16, it was in the range of 5 N/m ≦ P ≦ 15 N/m, and no concave defect or poor expansion was caused outside the copper foil composite.

On the other hand, in the case of lowering the temperature of the thermocompression bonding (130 ° C), hardening reaction of the epoxy resin hardly occurred, so in the case of Comparative Example 10 where the value of P was less than 5 N/m, the bonding strength at 150 ° C Less than 1.5 N/mm, resulting in a concave defect.

In the case of the comparative example 11 in which the epoxy resin in the epoxy-based adhesive is twice as large as the other examples, and the thickness of the copper foil and the thickness of the epoxy-based adhesive layer are thicker In the case of Comparative Example 13, P exceeded 15 N/m and the rigidity became high, resulting in poor expansion.

Even if P is higher to some extent, the overlap distance LA is not shortened. Therefore, in the case of Comparative Example 12 in which P × LA exceeds 45 mN, P is less than 15 N/m, but expansion failure occurs.

2. . . Copper foil

3, 8. . . Next layer

4. . . Resin film (PET film)

6. . . Epoxy adhesive (layer)

9. . . Sn-plated layer

10. . . Copper foil composite

10x. . . Concave

10y. . . Expansion department

20. . . Shielded body (cable)

30. . . jacket

30a. . . Jacket material

50. . . Electromagnetic wave shielding material

50e. . . Fixed end

50k. . . The overlap of the copper foil composites

50s. . . Rectangular piece

100. . . Shielding structure

201～203. . . Mold

300. . . Fixed wall

L. . . Long-side direction of copper foil composite

LA. . . Length of epoxy-based adhesive (layer) in the longitudinal direction

P. . . Unit width force

Fig. 1 is a cross-sectional view showing the configuration of an electromagnetic wave shielding material.

Fig. 2 is a view showing a state in which a copper foil composite (electromagnetic wave shielding material) is covered on a shielded body to perform shielding processing.

Fig. 3 is a view showing the appearance of a defect in a copper foil composite (shield structure) passing through each mold.

Fig. 4 is a schematic view showing a method of measuring p.

Fig. 5 is a view showing the relationship between the press-in depth of the indenter press-fitting portion and the press-in load when the length of the epoxy-based adhesive (layer) in the overlap portion is changed in the longitudinal direction.

2. . . Copper foil

3, 8. . . Next layer

4. . . Resin film (PET film)

6. . . Epoxy adhesive (layer)

9. . . Sn-plated layer

10. . . Copper foil composite

50. . . Electromagnetic wave shielding material

50k. . . The overlap of the copper foil composites

L. . . Long-side direction of copper foil composite

LA. . . Length of epoxy-based adhesive (layer) in the longitudinal direction

Claims (4)

An electromagnetic wave shielding material obtained by joining a plurality of copper foil composites in a longitudinal direction, wherein the copper foil composite is formed by laminating a copper foil and a resin film, and the copper foil composites are mutually The overlapping portion is followed by an epoxy-based adhesive, which is an epoxy resin and is selected from the group consisting of nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, and the like. A softening resin composed of one or more of a group of a pentadiene rubber, an amine ester rubber, and an acrylic rubber is used as a main component, and the epoxy-based adhesive which is interposed between the copper foil composites is long. The length LA in the side direction is 1 to 6 mm; the adhesion strength per unit width at 150 ° C of the overlapping portion of the copper foil composites is 1.5 N/mm or more. The electromagnetic wave shielding material according to the first aspect of the invention, wherein the overlapping portion of the copper foil composites is cut into a long side of a length of 7 mm in a direction perpendicular to the longitudinal direction to form a rectangular sheet. When one of the rectangular sheets is fixed at one end with a short side, the force P per unit width required to displace the point 5 mm from the fixed end to a deflection amount of 3 mm is 5 N/m ≦ P ≦ 15 N/m. For example, the electromagnetic wave shielding material of claim 2, wherein P×LA≦45mN. A method for producing an electromagnetic wave shielding material, comprising the steps of: overlapping steps: a plurality of copper foil composites in which a copper foil and a resin film are laminated in a longitudinal direction; and a bonding step: in which the copper foil composite overlaps each other, and the interlayer contains a material selected from the group consisting of nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, and isoprene rubber. One or more of the group of the urethane rubber and the acryl rubber are bonded to the epoxy-based adhesive of the epoxy resin; the overlapping strength of the copper foil composites at 150 ° C is 1.5 N per unit width. Mm or more.