JP6190528B2 - Conductive adhesive film, printed circuit board, and electronic device - Google Patents

Description

  The present invention relates to a conductive adhesive film, a printed circuit board, and an electronic device.

  Conventionally, there is a shield cap for shielding an electronic component provided on a printed circuit board from an electromagnetic wave entering from the outside and preventing the electromagnetic wave radiated from the electronic circuit from being emitted to the outside (for example, Patent Documents). 1). Such a shield cap is formed in a lid shape by a metal layer such as SUS, and is disposed so as to cover the electronic component to be protected. In addition, the shield cap is improved in that the metal layer is connected to the ground wiring pattern on the printed circuit board to enhance the shielding effect.

  By the way, since it is necessary for the shield cap to provide a gap between the electronic component and the inner wall surface so that the inner wall surface does not contact the electronic component on the printed circuit board, it is difficult to make the printed circuit board thinner. Thus, as disclosed in Patent Documents 2 and 3, there is one that prints a conductive paste on a printed circuit board. Patent Document 4 discloses that the entire substrate including a mounted product is covered with a heat-softening electromagnetic shield material that matches the shape of the substrate, and at least the shield material is heated and then cooled to adhere to the substrate. Has been.

JP 2001-345592 A JP 2009-016715 A JP 2010-245139 A JP-A-5-327270

  However, in Patent Documents 2 to 4, the manufacturing process is complicated or burdensome. Therefore, in recent years, the shield cap as in Patent Document 1 has become mainstream. Moreover, when making an electromagnetic shielding material follow the shape of an electronic component like patent document 4, the raise of resistance by an electromagnetic shielding material deform | transforming was a problem that the shielding effect will be reduced.

  Therefore, the present invention has been made in view of the above-described problems, and even if an electronic component is covered using a simple method such as press working, it is difficult to cause a problem that a shield performance is deteriorated due to an increase in electrical resistance. It is an object to provide a conductive adhesive film, a printed circuit board, and an electronic device that can be used.

  The present invention is a conductive adhesive film that shields an electromagnetic wave by extending a portion corresponding to a cutting concave portion of a printed wiring board in a film surface direction by pressing to cover an electronic component, and the first conductive particles A conductive adhesive layer formed of an isotropic conductive material, and an anisotropic conductive material that is positioned closer to the electronic component than the conductive adhesive layer during the pressing and includes second conductive particles And a base adhesive layer formed by

  When the electronic component is covered with the conductive adhesive film by press working, the conductive adhesive film is stretched according to the concave shape for cutting of the printed wiring board. At this time, the conductive adhesive film is greatly extended as it moves away from the electronic component. According to the above configuration, the conductive adhesive layer located on the outermost side from the electronic component is formed of the isotropic conductive material including the first conductive particles, and the base adhesive layer located on the electronic component side is the first adhesive layer. It is formed of an anisotropic conductive material including two conductive particles. Since the isotropic conductive material has a higher proportion of conductive particles than the anisotropic conductive material, even if the conductive adhesive layer extends larger than the base adhesive layer, the first conductive particles It is possible to suppress a decrease in conductivity due to the separation. As a result, it is possible to make it difficult to cause a problem that the shielding performance is deteriorated due to an increase in electrical resistance.

  In the conductive adhesive film of the present invention, the first conductive particles may be dispersed at a density such that at least some of the first conductive particles are in contact with each other in the conductive adhesive layer after extension.

  According to said structure, the fall of the electroconductivity of the site | part extended to the maximum in the electroconductive adhesive layer which is a site | part in which electroconductive particle is the most easily separated can be prevented effectively.

  In the conductive adhesive film of the present invention, the first conductive particles contained in the conductive adhesive layer are an average of 15% to 25% of the layer thickness before the conductive adhesive layer is extended. It is a flaky particle having a long diameter, and may be contained in an amount of 40 to 80% by weight based on the total weight of the conductive adhesive layer.

  According to the above configuration, in the conductive adhesive layer where the conductive particles are most likely to be separated from each other, the major axis direction of the first conductive particles is aligned with the film surface direction of the conductive adhesive layer. Since it becomes easy for the first conductive particles to come into contact with each other when processing is performed, it is possible to effectively prevent a decrease in the conductivity of the portion that has been extended to the maximum.

  Further, in the conductive adhesive film of the present invention, the second conductive particles have an average particle size that is in the range of 10% to 50% of the layer thickness before the extension of the base adhesive layer, It may be contained in an amount of 40 to 80% by weight based on the total weight of the base adhesive layer.

  According to the said structure, the fall of the electroconductivity in the whole foundation | substrate adhesive bond layer by space | interval of 2nd electroconductive particle can be prevented, and the fall of the shield performance by the increase in electrical resistance can be made hard to generate | occur | produce.

  In the conductive adhesive film of the present invention, the second conductive particles may be dendritic particles.

  According to the said structure, since the 2nd electroconductive particle is a dendrite-like particle | grain, compared with the case where the particle | grains different from a dendrite form are used for the same weight%, the contact rate of 2nd electroconductive particle | grains Can be increased. Thereby, it can prevent reducing the quantity of the adhesive agent of a base adhesive layer, and can improve electroconductivity, without reducing the adhesiveness of a conductive adhesive layer and a base adhesive layer.

  In the conductive adhesive film of the present invention, the layer thickness of the conductive adhesive layer before extension is 1% to 3% with respect to the groove depth of the recess, and the base adhesive layer is not extended. The layer thickness is 4% to 8% with respect to the groove depth of the recess, and the total thickness of both before extension is 5% to 11% with respect to the groove depth of the recess. Also good.

  In the conductive adhesive film of the present invention, the conductive adhesive layer may have a layer thickness of 10 μm to 30 μm, and the base adhesive layer may have a layer thickness of 40 μm to 80 μm.

  Further, in the conductive adhesive film of the present invention, a transfer film is laminated on the surface opposite to the base adhesive layer with respect to the conductive adhesive layer, and the transfer film has a temperature condition of 150 ° C. or higher. The storage elastic modulus below may be 20 MPa or less.

  According to the said structure, a transfer film is easy to be extended | stretched at the time of a hot press process, and the embedding property of the electroconductive adhesive film with respect to the recessed part for a cutting | disconnection of an electronic component and a printed wiring board can be made favorable.

  A shield printed wiring board according to the present invention includes the above-described conductive adhesive film.

  An electronic apparatus according to the present invention includes the shield printed wiring board described above.

  Even if the electronic component is covered with a conductive adhesive film using a simple method of press working, it is possible to make it difficult to cause a problem of a decrease in shielding performance due to an increase in electrical resistance.

It is sectional drawing of a conductive adhesive film. It is explanatory drawing which shows the detail of a conductive adhesive film. It is explanatory drawing which shows the press work of an electroconductive adhesive film. It is explanatory drawing which shows the aspect of the electroconductive adhesive film laminated | stacked on the glass epoxy board | substrate in an Example. It is explanatory drawing which shows the measuring method of the surface resistance value of the electroconductive adhesive film in an Example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the conductive adhesive film 1 of the present embodiment is provided on the shield printed wiring board 100 and covers the electronic component 2 by extending a portion corresponding to the recess in the film surface direction by pressing. Shields electromagnetic waves.

  Specifically, the printed wiring board 100 is provided with a circuit pattern including wiring such as a signal pattern and a ground pattern, a passive component such as a capacitor and an inductance, and an electronic component 2 such as an integrated circuit chip on the substrate 4. Yes. These electronic components 2 are integrally sealed by a sealing material 3 such as a resin mold. On the substrate 4, a large number of unit modules composed of the electronic components 2 that are integrally sealed are formed, each of which is defined by a concave groove (concave portion). The substrate 4 is cut by a concave portion for each unit module, and provided as a printed wiring board 100 in various electronic devices 300 such as a notebook computer and a tablet terminal. In addition, the recessed part for cutting | disconnection of the printed wiring board in this invention means the said recessed part.

(Conductive adhesive film 1)
The conductive adhesive film 1 is disposed so as to cover a large number of unit modules provided on the substrate 4 and is pressed. Thereby, the electroconductive adhesive film 1 is extended in the film surface direction so that the site | part located on a recessed part may enter into the groove | channel of a recessed part.

  Such a conductive adhesive film 1 has a conductive adhesive layer 10 and a base adhesive layer 11 located on the electronic component 2 side with respect to the conductive adhesive layer 10. That is, the conductive adhesive film 1 is formed by laminating a conductive adhesive layer 10 and a base adhesive layer 11.

  The conductive adhesive layer 10 and the base adhesive layer 11 are formed of a conductive adhesive that is a mixture of conductive particles and a binder. The electrical connection of the conductive adhesive is realized by continuous mechanical contact of the conductive particles in the binder and is maintained by the adhesive force of the binder.

  Examples of the binder for the conductive adhesive layer 10 and the base adhesive layer 11 include acrylic resins, epoxy resins, silicon resins, thermoplastic elastomer resins, rubber resins, polyester resins, and urethane resins. Can be mentioned. The adhesive may be a single substance or a mixture of the above resins. The binder may further contain a tackifier. Examples of the tackifier include fatty acid hydrocarbon resins, C5 / C9 mixed resins, rosin, rosin derivatives, terpene resins, aromatic hydrocarbon resins, and thermally reactive resins.

  As the conductive particles of the conductive adhesive layer 10 and the base adhesive layer 11, silver-coated copper obtained by silver-plating carbon, silver, copper, nickel, solder, aluminum, tin, bismuth, and copper powder. Further, a filler obtained by performing metal plating on a resin ball or glass bead or a mixture of these fillers is used.

  The shape of the conductive particles 10a and 11a may be any of a spherical shape, a needle shape, a fiber shape, a flake shape, and a dendrite shape. As shown in FIG. 2, in this embodiment, flaky conductive particles are used for the conductive particles 10a (first conductive particles) of the conductive adhesive layer 10, and the base adhesive layer 11 Dendritic conductive particles are used as the conductive particles 11a (second conductive particles).

(Conductive adhesive film 1: conductive adhesive layer 10)
The conductive adhesive layer 10 is formed of an isotropic conductive material including conductive particles 10a. The conductive adhesive layer 10 may have a multilayer structure of two or more layers. The lower limit of the thickness of the conductive adhesive layer 10 before extension is preferably 1.0% and more preferably 1.5% with respect to the groove depth of the recess. Moreover, 3.0% is preferable and, as for the upper limit of the layer thickness before extending | stretching of the conductive adhesive layer 10, it is more preferable that it is 2.0%. More specifically, the lower limit of the thickness of the conductive adhesive layer 10 is preferably 10 μm, and more preferably 15 μm. The upper limit of the layer thickness of the conductive adhesive layer 10 is preferably 30 μm, and more preferably 20 μm. If the lower limit of the conductive adhesive layer is less than the above value, when the conductive adhesive film 1 is stretched, it becomes difficult for the conductive particles to come into contact with each other. Will be. On the other hand, if the upper limit of the conductive adhesive layer exceeds the above value, the embedding property in the fine recesses is deteriorated and the economic rationality is lacking.

  Since the conductive adhesive layer 10 is formed of an isotropic conductive material, the conductive adhesive layer 10 has an electrically conductive state in all three dimensions including the thickness direction, the width direction, and the longitudinal direction. It can be secured.

  The conductive particles 10a are preferably dispersed at a density such that at least a part of the conductive particles 10a is in contact with each other in the conductive adhesive layer 10 after extension. Note that “at least a part is in contact with each other” means that all the conductive particles 10 a included in the conductive adhesive layer 10 after the extension are in contact (so as to be electrically connected). The conductive particles 10a that are in contact with each other so that at least the thickness direction, the width direction, and the longitudinal direction are electrically connected are not limited thereto.

  Specifically, the lower limit of the content ratio of the conductive particles 10a is preferably 40% by weight and more preferably 50% by weight with respect to the total weight of the conductive adhesive layer 10. Further, the upper limit of the content ratio of the conductive particles 10a is preferably 80% by weight and more preferably 60% by weight with respect to the total weight of the conductive adhesive layer 10. When the lower limit of the content ratio of the conductive particles is less than the above value, when the conductive adhesive film 1 is stretched, it becomes difficult for the conductive particles to come into contact with each other. It will be damaged. Moreover, when the upper limit of the content rate of electroconductive particle exceeds said value, while adhesiveness falls, economical rationality is missing.

  Like the electroconductive particle 10a of this embodiment, as a 1st electroconductive particle contained in the electroconductive adhesive layer 10, flake shaped particle | grains are preferable. The lower limit of the average major axis of the conductive particles 10a is preferably 15% of the layer thickness of the conductive adhesive layer 10 before extension, and more preferably 18%. Further, the upper limit of the average major axis of the conductive particles 10a is preferably 25% of the layer thickness before the conductive adhesive layer 10 is stretched, and more preferably 22%. When the shape of the first conductive particles 10a is a flaky shape having a major axis, the major axis of the conductive particles 10a included in the laminating step of the conductive adhesive layer 10 in the method for producing the conductive adhesive film 1 to be described later. The direction is aligned with the film surface direction of the conductive adhesive layer. As a result, when press processing is performed on a printed wiring board having a recess for cutting, the conductive particles 10a can easily come into contact with each other, effectively preventing a decrease in conductivity at the maximum extended portion. can do. The average major axis and average particle diameter of the conductive particles can be measured by a laser diffraction scattering method. Moreover, when the lower limit of the average major axis of the conductive particles 10a is smaller than 15% of the layer thickness before extension, the conductive particles 10 are less likely to contact each other when the conductive adhesive layer 10 is extended. Therefore, the conductivity of the site extended to the surface is impaired.

  Note that “the conductive adhesive layer 10 is formed of an isotropic conductive material” means that the conductive adhesive layer 10 is electrically connected in the thickness direction, the width direction, and the longitudinal direction. Show. That is, an isotropic conductive material is obtained by appropriately adjusting the shape of the conductive particles of the conductive adhesive layer 10, the type of binder, the mixing ratio of the conductive particles to the binder, the pressure at the time of pressure pressing, the temperature, and the like. .

(Conductive adhesive film 1: base adhesive layer 11)
The base adhesive layer 11 is formed of an anisotropic conductive material including conductive particles 11a. The base adhesive layer 11 may have a multilayer structure of two or more layers. 4% is preferable with respect to the groove depth of a recessed part, and, as for the minimum of the layer thickness before extension of the base adhesive layer 11, it is more preferable that it is 5%. Moreover, 8% is preferable and, as for the upper limit of the layer thickness before extension of the base adhesive bond layer 11, it is more preferable that it is 6%. More specifically, the lower limit of the layer thickness before the base adhesive layer 11 is extended is preferably 40 μm, and more preferably 50 μm. The upper limit of the layer thickness of the base adhesive layer 11 is preferably 80 μm, and more preferably 60 μm. When the lower limit of the base adhesive layer is less than the above value, when the conductive adhesive film 1 is stretched, it becomes difficult for the conductive particles to come into contact with each other. It will be. On the other hand, if the upper limit of the conductive adhesive layer exceeds the above value, the embedding property in the fine recesses is deteriorated and the economic rationality is lacking.

  The anisotropic conductive material forming the base adhesive layer 11 has a property of conducting only in the pressing direction. Therefore, the base adhesive layer 11 formed of the anisotropic conductive adhesive can ensure an electrical conduction state only in the thickness direction.

  The lower limit of the content ratio of the conductive particles 11a is preferably 40% by weight and more preferably 50% by weight with respect to the total weight of the base adhesive layer 11. Further, the upper limit of the content ratio of the conductive particles 11a is preferably 80% by weight and more preferably 60% by weight with respect to the total weight of the base adhesive layer 11. When the lower limit of the content ratio of the conductive particles is less than the above value, when the conductive adhesive film 1 is stretched, it becomes difficult for the conductive particles to come into contact with each other. It will be damaged. Moreover, when the upper limit of the content rate of electroconductive particle exceeds said value, while adhesiveness falls, economical rationality is missing.

  Like the electroconductive particle 11a of this embodiment, as the 1st electroconductive particle contained in the base adhesive layer 11, a dendrite-like particle | grain is preferable. The lower limit of the average particle diameter of the conductive particles 11a is preferably 10% of the layer thickness before the base adhesive layer 11 is extended, and more preferably 20%. Further, the upper limit of the average particle diameter of the conductive particles 11a is preferably 50%, more preferably 40%, of the layer thickness of the base adhesive layer 11 before extension.

  Note that “the base adhesive layer 11 is formed of an anisotropic conductive material” indicates that the base adhesive layer 11 is in a state where conduction is ensured only in one direction (thickness direction). That is, the anisotropic conductive material is obtained by appropriately adjusting the shape of the conductive particles of the base adhesive layer 11, the kind of binder, the mixing ratio of the conductive particles to the binder, the pressure at the time of pressure pressing, the temperature, and the like.

  In addition, the layer thickness before extension of the conductive adhesive film 1 itself, that is, the total thickness before extension of the conductive adhesive layer 10 and the base adhesive layer 11 (the thickness of the conductive adhesive layer 10 and the base adhesive layer 11). The lower limit of the sum of the thickness and the thickness of the recess is preferably 5%, more preferably 7% with respect to the groove depth of the recess. The upper limit of the thickness of the conductive adhesive film 1 itself before extension, that is, the total thickness before extension of the conductive adhesive layer 10 and the base adhesive layer 11 is preferably 11%, and 9%. More preferably.

(Method for producing conductive adhesive film 1)
As shown in FIG. 3, the conductive adhesive film 1 is placed on the electronic component 2 in a state where the transfer film 12 is laminated, and further pressed from above with the cushion film 13 placed. As a method for producing the conductive adhesive film 1, first, the transfer film 12 is extrusion-molded by a T-die method or the like to be formed into a film shape. The transfer film 12 is not particularly limited as long as it has releasability from the conductive adhesive layer 10. For example, a silicon or non-silicon melamine release agent or an acrylic release agent is used. Can be used. The transfer film 12 preferably has a storage elastic modulus of 20 MPa or less under a temperature condition of 150 ° C. or higher. Thereby, the embedding property to the recessed part for cutting | disconnection of the printed wiring board of the conductive adhesive film 1 at the time of press work becomes a favorable thing.

  By applying an isotropic conductive material containing conductive particles 10 a to the transfer film 12, the conductive adhesive layer 10 is laminated on the transfer film 12. On the other hand, the base adhesive layer 11 is formed by applying an anisotropic conductive material containing the conductive particles 11a to a release film (not shown) formed by extrusion, separately from this. Thereafter, by laminating these two laminates, a laminated structure in which the transfer film 12, the conductive adhesive layer 10, the base adhesive layer 11, and a release film (not shown) are sequentially laminated is formed.

  Thus, the conductive adhesive film 1 is formed in a state of being sandwiched between the transfer film 12 and the release film. In addition, this laminated structure may be wound, stored, transported, etc. with the above four-layer structure. Moreover, it may be wound in a three-layer structure in which only the release film is peeled off, and may be stored / transferred. In the case of winding with a three-layer structure, it is preferable that a release treatment is performed on the opposite surface of the transfer film 12 on which the conductive adhesive layer 10 is laminated.

  Moreover, it is not limited to forming by a laminate as mentioned above, The anisotropic conductive material which contains the electroconductive particle 11a further with respect to the laminated body by which the conductive adhesive layer 10 was laminated | stacked on the transfer film 12 You may form the base adhesive bond layer 11 by apply | coating. As a result, the conductive adhesive film 1 is laminated on the transfer film 12.

(Press working)
As shown in FIG. 3, the electronic component 2 integrally sealed with the sealing material 3 on the substrate 4 is covered with the conductive adhesive film 1 laminated on the transfer film 12, and on the transfer film 12 side. The press work is performed with the cushion film 13 placed. In the present embodiment, pressing is performed using a flat plate, but the present invention is not limited to this, and a mold for pressing into a recess may be used. In this case, the cushion film 13 may not be used.

  In the above detailed description, the present invention has been described mainly with respect to characteristic parts so that the present invention can be more easily understood. However, the present invention is not limited to the embodiments described in the above detailed description, and other implementations are possible. It can also be applied to forms and its scope should be interpreted as widely as possible.

  The terms and terminology used in the present specification are used to accurately describe the present invention, and are not used to limit the interpretation of the present invention. Moreover, it would be easy for those skilled in the art to infer other configurations, systems, methods, and the like included in the concept of the present invention from the concept of the invention described in this specification. Accordingly, the description of the claims should be regarded as including an equivalent configuration without departing from the technical idea of the present invention. In addition, in order to fully understand the object of the present invention and the effects of the present invention, it is desirable to fully consider the literatures already disclosed.

(Examples 1-4, Comparative Examples 1-3)
As an example, a conductive adhesive layer formed of an isotropic conductive material containing flaky conductive particles, and a base adhesive layer formed of an anisotropic conductive material containing dendritic conductive particles The conductive adhesive film which laminated | stacked was used. The thicknesses of the conductive adhesive layers of Examples 1 to 4 before being stretched by pressing were 20 μm, 20 μm, 15 μm, and 10 μm, respectively. Moreover, the thickness before extension by the press of the base adhesive layer of Examples 1-4 was 40 micrometers, 60 micrometers, 60 micrometers, and 80 micrometers, respectively.

  As Comparative Examples 1 and 2, a conductive adhesive layer formed of an anisotropic conductive material including dendritic conductive particles and a base formed of an isotropic conductive material including flaky conductive particles A conductive adhesive film laminated with an adhesive layer was used. Further, as Comparative Example 3, a conductive adhesive layer formed of an anisotropic conductive material containing dendritic conductive particles and a base formed of an anisotropic conductive material containing dendritic conductive particles A conductive adhesive film laminated with an adhesive layer was used. The thickness of the conductive adhesive layers of Comparative Examples 1 to 3 before being stretched by pressing was 60 μm, 80 μm, and 60 μm. Moreover, the thickness before the extension by the press of the base adhesive layer of Comparative Examples 1-3 was 20 micrometers, 20 micrometers, and 60 micrometers.

  In addition, the compounding ratios of the conductive particles in each of the conductive adhesive layers and the base adhesive layers in Examples 1 to 4 and Comparative Examples 1 to 3 are all in the conductive adhesive layer and the base adhesive layer, respectively. It is 60 wt% with respect to the total amount. Moreover, the average major axis and the average minor axis of the flaky conductive particles used in the conductive adhesive layers of Examples 1 to 4 and the base adhesive layers of Comparative Examples 1 and 2 are 5 μm and 1 μm, respectively. The average particle diameter of the dentrite-like conductive particles used in the base adhesive layers of Examples 1 to 4 and Comparative Example 3 and the conductive adhesive layers of Comparative Examples 1 to 3 is 13 μm. A transfer film was laminated on these conductive adhesive films, and a cushion film was further placed on the object to be pressed.

  As the transfer film, a polyolefin resin (thickness 50 μm) having a storage elastic modulus at 150 ° C. of 10 MPa was used. As the cushion film, CR1012MT4 (thickness 150 μm) manufactured by Mitsui Chemicals Tosero Co., Ltd. was used. The pressing was performed at a heating temperature of 170 ° C., a pressing time of 30 minutes, and a pressure of 3 MPa.

  Further, as an object to be pressed, an electronic component mounting substrate was simulated, and a glass epoxy substrate having a grid-like (8 × 8 section) recess having a groove width of 0.6 mm and a groove depth of 1 mm was used.

  As mentioned above, the electroconductive adhesive film was affixed on the press object by press work. Next, as shown in FIGS. 4 and 5 for the conductive adhesive films of Examples 1 to 4 and Comparative Examples 1 to 3 where the cushion film and transfer film were peeled off, the surface between all adjacent sections The resistance value was measured (total of 112 times). Specifically, as shown in FIG. 4, the glass epoxy substrate 20 has sections 20 a divided into 8 × 8 by the groove-like recesses 20 b as described above. The recesses 20b are provided on the glass epoxy substrate 20 in a grid pattern at intervals of 10 mm. As for the glass epoxy board | substrate 20, the electroconductive adhesive film 1 is press-processed so that at least one part of all the divisions 20a may be covered. That is, the 6 × 6 section 20a in the center on the glass epoxy substrate 20 is entirely covered with the conductive adhesive film 1, and a part of the section 20a located at the edge on the glass epoxy substrate 20 is partially covered. It is covered with a conductive adhesive film 1. By being pressed in such a manner, the conductive adhesive film 1 is embedded in the concave portion 20 b of the glass epoxy substrate 20. As a result, the concave portion 1 b is formed in the conductive adhesive film 1. That is, the conductive adhesive film 1 is formed with a section 1a delimited by the recess 1b. And as shown in FIG. 5, the surface resistance value R between the adjacent divisions 1a which pinch | interpose the recessed part 1b of the electroconductive adhesive film 1 was measured. Such measurement of the surface resistance value R was performed between all the sections 1a in Examples 1 to 4 and Comparative Examples 1 to 3 (112 patterns once). Table 1 shows the maximum value, the minimum value, the average value, and the evaluation of the surface resistance value R in Examples 1 to 4 and Comparative Examples 1 to 3.

  The evaluation was performed as follows. Specifically, the case where the average value, the maximum value, and the minimum value of the surface resistance values were all less than 1Ω was defined as “◯”. Further, the case where the average value of the surface resistance value was less than 1Ω but the maximum value was 1Ω or more was defined as “Δ”. Further, the case where the average value and the maximum value of the surface resistance value were 1Ω or more was defined as “x”.

  According to Table 1, the conductive adhesive layer is formed of an isotropic conductive material including flaky conductive particles, and the base adhesive layer is formed of an anisotropic conductive material including dendritic conductive particles. It can be seen that good results were obtained in the case of the conductive films of the examples. For example, Example 2 and Comparative Example 1 are in a mode in which the stacking order is changed, but the average surface resistance value of Example 2 is 1/10 of the average surface resistance value of Comparative Example 1. This indicates that good results can be obtained by the above configuration.

DESCRIPTION OF SYMBOLS 1 Conductive adhesive film 1a Section 1b Recess 2 Electronic component 3 Sealing material 4 Substrate 10 Conductive adhesive layer 10a Conductive particle 11 Base adhesive layer 11a Conductive particle 12 Transfer film 13 Cushion film 20 Glass epoxy substrate 20a Section 20b Recess 100 Printed wiring board 300 Electronic device

Claims (7)

A conductive adhesive film that shields electromagnetic waves by covering the electronic component by extending the portion corresponding to the concave portion for cutting of the printed wiring board in the film surface direction by pressing,
A conductive adhesive layer formed of an isotropic conductive material containing first conductive particles;
A base adhesive layer that is located on the electronic component side of the conductive adhesive layer during the press processing and is formed of an anisotropic conductive material containing second conductive particles ;
The first conductive particles are:
Flaky particles having an average major axis that is 15% to 25% of the layer thickness before extension of the conductive adhesive layer;
40% to 80% by weight of the conductive adhesive film based on the total weight of the conductive adhesive layer . The second conductive particles are:
Having an average particle size in the range of 10% to 50% of the layer thickness before extension of the underlying adhesive layer;
2. The conductive adhesive film according to claim 1 , wherein the conductive adhesive film is contained in an amount of 40 wt% to 80 wt% with respect to the total weight of the base adhesive layer. The conductive adhesive film according to claim 2 , wherein the second conductive particles are dendritic particles. The conductive adhesive layer has a layer thickness of 10 μm to 30 μm,
The underlying adhesive layer, the conductive adhesive film according to any one of claims 1 to 3, characterized in that it has a layer thickness of 40Myuemu～80myuemu. For the conductive adhesive layer, a transfer film is laminated on the surface opposite to the base adhesive layer,
The transfer film, the conductive adhesive film according to any one of claims 1 to 4, wherein the storage elastic modulus is less than 20MPa at a temperature of more than 0.99 ° C.. Shielded printed circuit board, characterized in that it comprises a conductive adhesive film according to any one of claims 1 to 5. An electronic apparatus comprising the shield printed wiring board according to claim 6 .