TWI501708B - Shielded printed circuit boards - Google Patents

Description

Shielded printed circuit board

The present invention relates to a shielded printed circuit board for a portable telephone, a computer, or the like.

In the past, electronic devices such as mobile phones and computers have been affected by noise such as electromagnetic waves from the main board or the outside due to miniaturization and high-speed processing. Therefore, there is an increasing demand for a printed circuit board having a shielding film that shields noise such as electromagnetic waves. Further, such a printed circuit board is connected to an electronic component used in a portable telephone, a computer, or the like, and may be twisted and deformed at a mounting portion where an electronic component is mounted due to bending during use or the like. Therefore, the above problem is solved by providing the reinforcing member at a position opposite to the mounting portion where the electronic component is mounted.

For example, FIG. 5 is a schematic diagram of a conventional shielded printed circuit board 100. As shown in FIG. 5, the shield printed circuit board 100 includes a printed circuit board 110 including: a base member 112 formed with grounding circuit patterns 114, 115; and an insulating film 111 disposed on the base member through the bonding layer 113 The grounding circuit patterns 114, 115 are covered on 112. Further, a shielding film 120 including a conductive material 123, a conductive layer 122, and an insulating layer 121 in this order is provided on the insulating film 111 of the shield printed circuit board 100. Here, the hole portion 140 through which the ground circuit pattern 114 is exposed is formed in the insulating film 111 and the bonding layer 113 of the printed circuit board 110. Since the conductive material 123 of the shielding film 120 is filled in the hole portion 140, the conductive layer 122 and the grounding circuit pattern 114 are turned on to maintain both potentials. Thereby, the electromagnetic wave 90a radiated to the printed circuit board 110 can be shielded by the shielding film 120. Further, the electronic component 150 is connected to a mounting portion provided on the lower surface of the printed circuit board 110. Further, a reinforcing member 135 is provided at a position on the printed circuit board 110 opposite to the mounting portion of the electronic component 150.

Here, the printed circuit board 110 and the electronic component 150 connected thereto may be affected by noise from the external electromagnetic wave 90b or the like, and therefore, the portion where the electronic component 150 is mounted also needs to have a shielding effect. Therefore, a material having conductivity is used in the reinforcing member 135 so that the reinforcing member 135 has a shielding effect, so that the reinforcing member 135 achieves both the reinforcing effect and the shielding effect.

Here, in order to provide the reinforcing member 135 with a sufficient shielding effect, it is necessary to maintain the reinforcing member 135 and the grounding circuit patterns 114 and 115 at the same potential. For this reason, in the prior art, a grounding member (not shown) is separately provided outside the shield printed circuit board 100, and the reinforcing member 135 and the grounding circuit patterns 114 and 115 are held at the same potential by the grounding member. However, when the grounding member is provided outside the shield printed circuit board 100, for example, there is a problem in that the area for shielding the printed circuit board is required because wiring or the like for connecting the reinforcing member 135 and the grounding member needs to be provided. It will increase accordingly, resulting in limited design freedom.

Therefore, in the conventional shield printed circuit board 100, the grounding circuit pattern 115 is disposed directly under the reinforcing member 135, and the hole portion 160 is formed in the insulating film 111 and the bonding layer 113 to expose the grounding circuit pattern 115, and The hole portion 160 is filled with a branch-shaped conductive bonding agent 130 to maintain the reinforcing member 135 and the grounding circuit pattern 115 at the same potential.

For example, Patent Document 1 discloses a flexible printed circuit board in which a reinforcing member and a grounding circuit pattern are maintained at the same potential by the above method. In the flexible printed circuit board, the metal reinforcing plate and the grounding circuit are kept at the same potential by filling the opening for exposing the grounding circuit with the conductive bonding agent, thereby providing the metal reinforcing plate with a shielding effect.

Patent Document 1: Japanese Patent Application Publication No. 2009-218443

However, as described above, when the conductive bonding agent 130 is filled in the hole portion 160, voids 160a and 160b may be formed in the connection portion between the conductive bonding agent 130 and the grounding circuit pattern 115. The reason for this is that the connection portion of the conductive bonding agent 130 and the grounding circuit pattern 115 is sandwiched by a hard material such as the reinforcing member 135 and the base member 112, and the conductive bonding agent is applied when the reinforcing member 135 is attached. 130 does not fully meet the steps of the hole portion 160. In this case, in the reflow step of mounting the shield printed circuit board 100 on the main board of the portable telephone, the computer or the like, the gap 160a and the gap 160b are heated and expanded, thereby causing the conductive bonding agent 130 and the grounding circuit pattern 115. A sufficient electrical connection cannot be achieved between. As a result, there arises a problem that, for example, a defective appearance is caused, the reinforcing member 135 cannot be maintained at the ground potential, and it is difficult to secure a sufficient shielding effect or the like.

Further, in order to prevent the gaps 160a and 160b from being formed in the connection portion between the conductive bonding agent 130 and the grounding circuit pattern 115, it is necessary to thicken the thickness of the conductive bonding agent 130 as much as possible. In this case, in order to maintain conductivity The ratio of the conductive particles contained in the conductive bonding agent 130 needs to be increased, which leads to a corresponding increase in cost and inefficiency. Further, according to the above method, it is necessary to arrange the grounding circuit pattern 115 directly under the reinforcing member 135, and there is a problem that the degree of freedom in design is limited.

The present invention has been made in view of the above problems, and an object thereof is to provide a design that can ensure design freedom even when a reinforcing member is provided at a position facing an electronic component in a printed circuit board to which an electronic component is connected. A shielded printed circuit board that maintains a shielding effect on the mounting portion of an electronic component.

The shielded printed circuit board of the present invention comprises: a printed circuit board, a shielding film, and a reinforcing member, wherein the printed circuit board includes: a base member formed with a grounding circuit pattern; and an insulating film disposed on the base member and covering the above a circuit pattern for grounding, wherein an electronic component is connected to a mounting portion provided on a lower surface of the base member; the shielding film is provided on the printed circuit board, and includes a conductive layer that is equipotential to the grounding circuit pattern a part or all of a region disposed on the upper surface of the printed circuit board and covering the mounting portion; and an insulating layer disposed on the conductive layer; the reinforcing member having electrical conductivity and disposed on the shielding film and The shield printed circuit board according to the present invention is characterized in that the reinforcing member is bonded to the insulating layer by a conductive bonding agent containing spherical conductive particles; the insulating layer has a layer thickness smaller than the conductive particles. a state in which the conductive bonding agent is bonded to the insulating layer The conductive adhesive from protruding length, the conductive particles are in contact with the conductive layer in a state where the conductive adhesive and bonded to the insulating layer.

According to the above configuration, the conductive layer having the same potential as the grounding circuit pattern is disposed on the printed circuit board, and the conductive layer covers a part or all of the region facing the mounting portion of the electronic component. Thereby, electromagnetic waves radiated from the external mounting portion of the electronic component can be shielded by the shielding film having the conductive layer. Further, a region opposed to the mounting portion of the electronic component is reinforced by the reinforcing member provided on the shielding film. Thereby, deformation or the like at the mounting portion due to bending or the like can be prevented by the reinforcing member. Further, the reinforcing member is bonded to the insulating layer of the shielding film by the conductive bonding agent, and the conductive particles included in the conductive bonding agent are in contact with the conductive layer of the shielding film in a state where the conductive bonding agent is bonded to the insulating layer, and thus The potential of the reinforcing member having conductivity and the potential of the conductive layer are brought to the same potential, so that the reinforcing member can also have a shielding effect. Thereby, it is possible to more reliably provide a shielding effect to the mounting portion of the electronic component by the double effect, which includes the shielding effect of the shielding film and the shielding effect of the reinforcing member. Therefore, it is not necessary to expose the grounding circuit pattern for the potential of the reinforcing member to be equal to the ground potential as in the prior art and to connect the reinforcing member and the grounding circuit pattern together by the conductive bonding agent, so that it is not necessary to The position is configured to form a circuit pattern for grounding, thereby increasing design freedom. Further, since it is not necessary to connect the reinforcing member and the grounding circuit pattern by the conductive bonding agent, defects at the time of reflow due to the voids occurring in the connecting portion do not occur. As described above, both the design freedom and the shielding effect can be ensured. In addition, since the conductive particles are spherical, the length of the conductive bonding agent protruding from the conductive bonding agent is substantially constant in the layer thickness direction regardless of the direction in which the conductive particles are inclined. Thus, for example, the spherical conductive particles are more likely to break through the insulating layer and are more likely to come into contact with the conductive layer than the flake or dendritic shape. As a result, the reinforcing member and the conductive layer can be more reliably maintained at the same potential.

Further, in the shield printed wiring board of the present invention, the reinforcing member may be connected to an external grounding member, wherein the external grounding member and the grounding circuit pattern are kept at the same potential.

According to the configuration described above, the reinforcing member is held at the same potential as the grounding circuit pattern by the conductive particles contained in the conductive bonding agent, and the external grounding member and the grounding circuit pattern are kept at the same potential. Improve the shielding effect.

Further, in the shield printed wiring board of the present invention, the insulating layer of the shielding film is coated on the conductive layer.

According to the above configuration, since the insulating layer of the shielding film is applied to the conductive layer, for example, the insulating layer of the shielding film is thinner than the film-shaped insulating layer, and the conductive particles protruding from the conductive bonding agent are formed. It is easy to break through the contact of the insulating layer with the conductive layer.

Further, in the shield printed wiring board of the present invention, the reinforcing member is formed of a stainless steel material.

According to the above configuration, since the stainless steel material has hardness suitable for reinforcement and excellent corrosion resistance, it is possible to more effectively reinforce the mounting portion of the electronic component and provide a shielding effect to the mounting portion.

According to the shield printed circuit board of the present invention, electromagnetic waves radiated from the external mounting portion of the electronic component can be shielded by the conductive shielding film. Further, deformation or the like occurring at the mounting portion due to bending or the like can be prevented by the reinforcing member. Further, the potential of the conductive reinforcing member and the potential of the conductive layer can be at the same potential, and the reinforcing member can also have a shielding effect. Thereby, it is possible to more reliably provide a shielding effect to the mounting portion of the electronic component according to the double effect, which includes the shielding effect of the shielding film and the shielding effect of the reinforcing member. Therefore, it is not necessary to expose the grounding circuit pattern for the reinforcing member at the ground potential as in the prior art and to connect the reinforcing member and the grounding circuit pattern by the conductive bonding agent, and therefore, it is not necessary to follow the arrangement position of the reinforcing member. A circuit pattern for grounding is formed, thereby increasing design freedom. Further, since it is not necessary to connect the reinforcing member and the grounding circuit pattern by the conductive bonding agent, defects at the time of reflow due to the voids occurring in the connecting portion do not occur. As described above, both the design freedom and the shielding effect can be ensured. Further, for example, spherical conductive particles are more likely to break through the insulating layer and are more likely to come into contact with the conductive layer 22 than in the form of flakes or dendrites. As a result, the reinforcing member and the conductive layer can be more reliably maintained at the same potential.

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

(Shielding the overall structure of the printed circuit board 1)

First, the shield printed circuit board 1 of the present embodiment will be described using FIG. As shown in FIG. 1, the shield printed circuit board 1 includes a printed circuit board 10, a shielding film 20, and a reinforcing member 35. Further, an electronic component 50 is connected to a mounting portion provided on the lower surface of the printed circuit board 10. In addition, the shielding film 20 is disposed on the printed circuit board 10 and covers a part or all of a region opposing the mounting portion where the electronic component 50 is attached. Thereby, noise of the electromagnetic wave 90b or the like radiated from the externally mounted portion of the electronic component 50 is shielded by the shielding film 20.

Further, the reinforcing member 35 is provided on the shielding film 20, and is disposed at a position opposite to the mounting portion where the electronic component 50 is attached. The reinforcing member 35 is bonded to the conductive bonding agent 30 in a contact state, and is attached to the insulating layer 21 of the shielding film 20 by the conductive bonding agent 30. Here, the enlarged portion a of FIG. 1 is an enlarged view showing a state of bonding between the conductive bonding agent 30 and the insulating layer 21 of the shielding film 20, wherein the conductive bonding agent 30 is bonded to the reinforcing member 35 in a contact state. . As shown in the enlarged portion a, the conductive bonding agent 30 includes the conductive particles 32 and the bonding agent 31, and the conductive particles 32 protrude from the bonding agent 31. Further, the reinforcing member 35 joined to the upper surface of the conductive bonding agent 30 in a contact state is in contact with the conductive particles 32. On the other hand, the conductive particles 32 protruding from the lower surface of the conductive bonding agent 30 break through the insulating layer 21 of the shielding film 20 and are in contact with the conductive layer 22 therebelow. Thereby, the reinforcing member 35 and the conductive layer 22 of the shielding film 20 are electrically connected by the conductive particles 32 of the conductive bonding agent 30, so that the reinforcing member 35 having conductivity and the conductive layer 22 can be at the same potential. Therefore, the reinforcing member 35 having conductivity can be provided with a shielding effect.

Thereby, the reinforcing member 35 for shielding the printed circuit board 1 can at least have a dual function of reinforcing the mounting portion of the electronic component 50 and shielding the electromagnetic wave 90b radiated from the mounting portion of the electronic component 50 from the outside. The noise.

Hereinafter, each structure will be specifically described.

(printed circuit board 10)

The printed circuit board 10 includes a base member 12 formed with a plurality of circuit patterns such as a signal circuit pattern (not shown) and a ground circuit pattern 14 and the like; an adhesive layer 13 disposed on the base member 12; and an insulating film 11 Engaged with the bonding layer 13.

A signal circuit pattern (not shown), a ground circuit pattern 14 and the like are formed on the upper surface of the base member 12. These circuit patterns are formed by performing an etching treatment on the conductive material. Further, the grounding circuit pattern 14 therein refers to a pattern that maintains a ground potential.

The bonding agent layer 13 is a bonding agent between the signal circuit pattern and the grounding circuit pattern 14 and the like and the insulating film 11, and has an effect of maintaining insulation and bonding the insulating film 11 and the base member 12 to each other. Further, the thickness of the bonding layer 13 is from 10 μm to 40 μm, and may be appropriately set without particular limitation.

Both the base member 12 and the insulating film 11 are made of engineering plastic. For example, it may be polyethylene terephthalate, polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimide amide, polyetherimide, polyphenylene sulfide Resin. An inexpensive polyester film is preferred in the case where heat resistance is not required. When a flame retardancy is required, a polyphenylene sulfide film is preferable, and when heat resistance is also required, a polyimide film is preferable. Further, the base member 12 has a thickness of 10 μm to 40 μm, and the insulating film 11 has a thickness of 10 μm to 30 μm, which can be appropriately set without particular limitation.

Further, in the insulating film 11 and the bonding layer 13, the hole portion 40 is formed by laser processing or the like. The hole portion 40 is for exposing a partial region of the circuit pattern selected from the plurality of grounding circuit patterns and signal circuit patterns. In the present embodiment, the hole portion 40 is formed in the insulating film 11 and the bonding layer 13 along the laminating direction so that a partial region of the grounding circuit pattern 14 is exposed. In addition, the hole portion 40 is provided with an appropriate aperture so that adjacent other circuit patterns are not exposed.

(reinforcing part 35)

The reinforcing member 35 is formed of a material having electrical conductivity, such as a stainless steel material. Further, the reinforcing member 35 is provided at a position facing the mounting portion of the electronic component 50 on the shielding film 20, and the mounting portion of the electronic component 50 is reinforced to prevent distortion or the like from occurring at the mounting portion due to bending or the like. Further, the reinforcing member 35 is not limited to a stainless steel material, and any material capable of reinforcing the mounting portion and having electrical conductivity may be used. However, since the stainless steel material has hardness suitable for reinforcement and excellent corrosion resistance, the use of the stainless steel material can more effectively reinforce the electron. The mounting location of the component 50 can provide a shielding effect to the mounting location. Further, in order to improve the electrical connectivity of the electronic component 50, it is preferable to perform nickel plating on the surface of the stainless steel material. Further, the thickness of the reinforcing member 35 is 0.05 mm to 1 mm, and can be appropriately set depending on the configuration.

(conductive bonding agent 30)

The conductive bonding agent 30 is formed of any one of an isotropic conductive bonding agent and an anisotropic conductive bonding agent. Isotropic conductive bonding agents have the same electrical properties as existing solders. Therefore, when the conductive bonding agent 30 is formed of an isotropic conductive bonding agent, it is possible to ensure a conductive state in all directions of the three-dimensional space formed in the thickness direction, the width direction, and the longitudinal direction. On the other hand, when the conductive bonding agent 30 is formed of an anisotropic conductive bonding agent, it can be ensured that it is in a conductive state only in a two-dimensional direction constituted by the thickness direction.

Further, the conductive bonding agent 30 may be formed of a conductive bonding agent obtained by mixing the conductive particles 32 having a soft magnetic material as a main component and the bonding agent 31. In this case, the conductive particles 32 exhibit a high magnetization, and even for high-frequency electromagnetic waves, the decrease in magnetic permeability can be suppressed, and the radio waves can be absorbed. Thereby, the combination with the reinforcing member 35 has a function of absorbing electric waves in addition to the function of shielding effect.

Specifically, the conductive bonding agent 30 is formed as a mixture of the conductive particles 32 and the bonding agent 31. That is, the conductive bonding agent 30 is configured by dispersing the conductive particles 32 in the bonding agent 31. The electrical connection of the conductive bonding agent 30 is achieved by continuously contacting one or a plurality of conductive particles 32 in the bonding agent 31 in the thickness direction of the conductive bonding agent 30, and is held by the bonding force of the bonding agent 31.

Examples of the bonding agent 31 included in the conductive bonding agent 30 include an acrylic resin, an epoxy resin, an anthracene resin, a thermoplastic elastomer resin, a rubber resin, a polyester resin, and a urethane resin. Further, the bonding agent 31 may be a monomer of the above resin, or may be a mixture of the above resins. In addition, the bonding agent 31 may further contain a tackifier. Examples of the tackifier include a thickener such as a fatty acid hydrocarbon resin, a C5/C9 mixed resin, a rosin, a rosin derivative, a terpene resin, an aromatic hydrocarbon resin, and a heat-reactive resin.

A part or all of the conductive particles 32 included in the conductive bonding agent 30 are formed of a metal material. For example, the conductive particles 32 are copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders can be subjected to atomization or carbonylation. ) to prepare. Further, in addition to the above, particles obtained by coating a metal powder with a resin or particles obtained by coating a resin with a metal powder may be used. Further, the conductive particles 32 are preferably silver-coated copper powder or silver-coated nickel powder. The reason for this is because the conductive particles 32 having stable conductivity can be obtained from an inexpensive material. Further, the shape of the conductive particles 32 is not limited to a spherical shape, and for example, a convex shape may be formed on the spherical surface based on a spherical shape. In this case, the conductive particles 32 will more easily break through the insulating layer 21. In the case where the conductive particles 32 have a spherical shape, the conductive particles 30 are inclined in any direction regardless of the direction in which the conductive particles are inclined, and the length of the conductive particles protruding from the conductive bonding agent 30 is in the layer thickness direction. It is roughly certain. Thereby, for example, the conductive particles 32 will be more likely to break through the insulating layer 21 than the sheet shape or the branch shape, and are easily brought into contact with the conductive layer 22.

In the conductive bonding agent 30 having the structure as described above, the thickness of the bonding agent 31 is 5 μm to 40 μm, and the average particle diameter of the conductive particles 32 is 10 μm to 100 μm. Further, the average particle diameter of the conductive particles 32 is 1.5 to 3 times the thickness of the bonding agent 31. Therefore, a part of the conductive particles 32 protrudes from the bonding agent 31 of the conductive bonding agent 30. Further, the variation in the average particle diameter of the conductive particles 32 is preferably within ±5 μm. In this case, since the protruding length of the conductive particles 32 protruding from the conductive bonding agent 30 does not largely vary, the connection resistance with the conductive layer 22 is stabilized. Thereby, the reinforcing member 35 and the conductive layer 22 can be stably maintained at the same potential. Further, the amount of the conductive particles 32 to be mixed with the bonding agent 31 is 30% by weight to 70% by weight, and is preferably 50% by weight from the viewpoint of bonding strength and conductivity.

(Shielding film 20)

The shielding film 20 includes a conductive layer 22 bonded to the conductive material 23 in a contact state, and an insulating layer 21 disposed on the conductive layer 22.

The conductive material 23 is formed of an isotropic conductive bonding agent or an anisotropic conductive bonding agent. Isotropic conductive bonding agents have the same electrical properties as existing solders. Therefore, when the conductive material 23 is formed of an isotropic conductive bonding agent, it is ensured that the conductive state is in all directions in the three-dimensional space composed of the thickness direction, the width direction, and the longitudinal direction. On the other hand, in the case where the conductive material 23 is formed of an anisotropic conductive bonding agent, it is ensured that it is in a conductive state only in a two-dimensional direction constituted by the thickness direction. Further, when the conductive material 23 is formed of an isotropic conductive bonding agent, since the conductive material 23 may have the function of the conductive layer 22, the conductive layer 22 may not be provided.

Further, the conductive material 23 is composed of an insulating bonding agent and conductive particles dispersed in an insulating bonding agent. Specifically, the insulating bonding agent may be composed of the following materials as a bonding resin: thermoplastics such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, and acrylic. Resins, or thermosetting resins such as phenols, epoxies, urethanes, melamines, and alkyds. Further, conductive particles such as a metal or carbon are mixed into these conjugate resins to form a conductive conductive adhesive. When the heat resistance is not particularly required, a polyester-based thermoplastic resin which is not restricted by storage conditions or the like is preferably used. When heat resistance or excellent flexibility is required, it is preferable to use a highly reliable epoxy-based thermosetting resin. Further, in either case, a material having a small resin flow at the time of hot pressing is preferable. In addition, the thickness of the conductive material 23 is from 3 μm to 30 μm, but may be appropriately set without particular limitation.

Further, the conductive particles included in the conductive material 23 have an average particle diameter smaller than the pore diameter of the hole portion 40 so that the conductive particles enter the hole portion 40. Further, some or all of the conductive particles are formed of a metal material. For example, the conductive particles are copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders can be prepared by an atomization method, a carbonylation method, or the like. Further, in addition to the above, particles obtained by coating a metal powder with a resin or particles obtained by coating a resin with a metal powder may be used. Further, the conductive particles are preferably silver-coated copper powder or silver-coated nickel powder. The reason for this is because conductively stable conductive particles can be obtained from inexpensive materials. Further, the shape of the conductive particles of the conductive material 23 is not necessarily limited to a spherical shape, and may be, for example, a sheet shape or a dendritic shape.

The conductive layer 22 has a shielding effect, that is, shielding unnecessary radiation in an electric signal sent from the main board and noise from an external electromagnetic wave or the like. The conductive layer 22 is a metal layer formed of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium or zinc, or formed of an alloy containing any of these materials, or An alloy containing two or more of these materials is formed. Further, as the metal material, it may be appropriately selected depending on the desired shielding effect. However, copper has a problem that oxidation tends to occur when it comes into contact with the atmosphere, and gold is expensive, so inexpensive aluminum or highly reliable silver is preferable. . Further, the thickness of the film may be appropriately selected depending on the desired shielding effect and resistance to repeated bending and sliding, but the thickness is preferably from 0.01 μm to 10 μm. When the thickness is less than 0.01 μm, a sufficient shielding effect cannot be obtained, and when it exceeds 10 μm, flexibility is a problem. In addition, the method of forming the conductive layer 22 includes a vacuum deposition method, a sputtering method, a CVD method, an MO (metal organic method) method, a plating method, a sheet method, etc., and if mass production is considered, a vacuum deposition method is preferable, and An inexpensive and stable conductive layer 22 is obtained. Further, as described above, when the conductive material 23 is formed of an isotropic conductive bonding agent, the conductive layer 22 may not be provided.

The insulating layer 21 is formed of a resin such as epoxy, polyester, acrylic, phenol, or urethane or a mixture of these resins, and functions to maintain insulation and cover so that the conductive layer 22 is not directly exposed. . Further, the insulating layer 21 has a thickness of 1 μm to 10 μm, and the insulating layer 21 is formed by directly coating the conductive layer 22, which is formed thinner than the film shape, for example, so that the conductive particles 32 can be more easily broken. Insulation layer 21.

Further, when the reinforcing member 35 is provided on the shielding film 20 by the conductive bonding agent 30, the conductive bonding agent 30 is bonded to the insulating layer 21 in the shielding film 20. At the time of the above bonding, the insulating layer 21 is heated from the reinforcing member 35 side to be softened. Thus, the insulating layer 21 is softened by heating, and the conductive particles 32 of the conductive bonding agent 30 are likely to break through the insulating layer 21. Therefore, the resin such as epoxy which forms the insulating layer 21 is formed of a resin which can be softened at a heating temperature when the reinforcing member 35 is provided on the insulating layer 21.

Here, when the conductive bonding agent 30 and the insulating layer 21 are bonded as shown in the enlarged portion a of FIG. 1, a part of the conductive particles 32 included in the conductive bonding agent 30 protrudes from the lower surface of the bonding agent 31, and the conductivity The protrusion of the particle 32 breaks through the insulating layer 21 and is in contact with the conductive layer 22. Therefore, the layer thickness L1 of the insulating layer 21 is set to be smaller than the protruding length L2 of the conductive particles 32 protruding from the conductive bonding agent 30. Specifically, in the case where the thickness of the bonding agent 31 of the conductive bonding agent 30 is 5 μm to 15 μm and the average particle diameter of the conductive particles 32 is 10 μm to 20 μm, the protruding length L2 of the conductive particles 32 is 5 μm to 15 μm, The thickness of the insulating layer 21 is in the range of 2 μm to 12 μm. Further, as shown in FIG. 1, the conductive particles 32 are arranged one by one in the layer thickness direction of the conductive bonding agent 30 and arranged in a line in a direction orthogonal to the layer thickness direction. For example, two or three rows of conductive particles 32 may be stacked in the layer thickness direction of the conductive bonding agent 30. That is, in the present embodiment, the reinforcing member 35 and the conductive layer 22 are electrically connected by one conductive particle 32 in the layer thickness direction of the conductive bonding agent 30, but the present invention is not limited thereto, and the conductive bonding agent 30 may be used. A plurality of conductive particles 32 are superposed on each other in the layer thickness direction, and the reinforcing member 35 and the conductive layer 22 are electrically connected by the plurality of conductive particles 32. The layer thickness of the insulating layer 21 may be set to be smaller than the protruding length of the conductive particles 32 protruding from the conductive bonding agent 30.

In the shield film 20 having the above configuration, the conductive material 23 enters the hole portion 40 and comes into contact with the grounding circuit pattern 14 that is exposed. Thereby, the conductive layer 22 is electrically connected to the grounding circuit pattern 14 by the conductive material 23 joined in the contact state and is kept at the same potential. Thereby, the shielding film 20 has a shielding effect, so that noise such as electromagnetic waves 90a from the outside can be shielded.

Further, the shielding film 20 is disposed so as to cover a part or all of a region facing the mounting portion of the electronic component, and the electronic component is connected to the printed circuit board 10 at the mounting portion. Thereby, the noise of the electromagnetic wave 90b or the like radiated from the externally mounted portion of the electronic component 50 can be shielded by the shielding film 20.

Further, the conductive particles 32 protruding from the lower surface of the conductive bonding agent 30 can break through the insulating layer 21 of the shielding film 20 and come into contact with the conductive layer 22 therebelow. Thereby, the reinforcing member 35 and the conductive layer 22 of the shielding film 20 are electrically connected by the conductive particles 32 of the conductive bonding agent 30, so that the reinforcing member 35 having the conductivity and the conductive layer 22 can be at the same potential.

As described above, the shield printed circuit board 1 of the present embodiment includes the printed circuit board 10, the shielding film 20, and the reinforcing member 35, wherein the printed circuit board 10 includes the base member 12 on which the grounding circuit pattern 14 is formed, and is provided on the substrate. The insulating film 11 of the grounding circuit pattern 14 is covered on the member 12, and the electronic component 50 is connected to the mounting portion provided on the lower surface of the base member 12. The shielding film 20 is disposed on the printed circuit board 10, including: for grounding The circuit pattern 14 is at a potential potential and covers a part or all of the conductive layer 22 of the region opposite to the mounting portion, and the insulating layer 21 disposed on the conductive layer 22; the reinforcing member 35 is disposed on the shielding film 20 opposite to the mounting portion. Further, in the shield printed circuit board 1, the reinforcing member 35 is bonded to the insulating layer 21 by the conductive bonding agent 30 containing the spherical conductive particles 32, and the layer thickness of the insulating layer 21 is smaller than that of the conductive particles 32. The protruding length from the conductive bonding agent 30 in a state where the conductive bonding agent 30 is bonded to the insulating layer 21, and the conductive particles 32 are bonded to the insulating layer 30 at the conductive bonding agent 30. In contact with the conductive layer 22 in the state.

According to the above configuration, the conductive layer 22 having the same potential as the grounding circuit pattern 14 is disposed on the printed circuit board 10, and the conductive layer 22 covers a part or all of the region facing the mounting portion of the electronic component 50. Thereby, the electromagnetic wave 90a radiated from the mounting portion of the electronic component 50 by the outside can be shielded by the shielding film 20 having the conductive layer 22. Further, a region opposed to the mounting portion of the electronic component 50 is reinforced by the reinforcing member 35 provided on the shielding film 20. Thereby, deformation or the like which occurs in the mounting portion due to bending or the like can be prevented by the reinforcing member 35. Further, the conductive particles 32 included in the conductive bonding agent 30 are in contact with the conductive layer 22 of the shielding film 20 in a state where the conductive bonding agent 30 is bonded to the insulating layer 21, wherein the conductive bonding agent 30 is used for the reinforcing member. 35 is bonded to the insulating layer 21 of the shielding film 20. Therefore, the potential of the conductive reinforcing member 35 and the potential of the conductive layer 22 can be at the same potential, and the reinforcing member 35 can also have a shielding effect. Thereby, the double effect of the shielding effect of the shielding film 20 and the shielding effect of the reinforcing member 35 can more reliably provide a shielding effect to the mounting portion of the electronic component 50. Therefore, it is not necessary to expose the grounding circuit pattern 14 and connect the reinforcing member 35 and the grounding circuit pattern 14 by the conductive bonding agent in order to make the reinforcing member 35 at the ground potential as in the prior art, and therefore, it is not necessary to follow the reinforcing member 35. The position is arranged to form the grounding circuit pattern 14, thereby increasing the degree of design freedom. Further, since it is not necessary to connect the reinforcing member 35 and the grounding circuit pattern 14 by the conductive bonding agent, defects at the time of reflow due to the occurrence of voids in the connecting portion do not occur. As mentioned above, both design freedom and shielding effectiveness can be ensured. In addition, since the conductive particles 32 are spherical in the conductive bonding agent 30, the length of the conductive particles 32 protruding from the conductive bonding agent 30 is substantially constant in the layer thickness direction. Thus, for example, the conductive particles 32 will more easily break through the insulating layer 21 to be more easily in contact with the conductive layer 22 than in the form of flakes or dendrites. As a result, the reinforcing member 35 and the conductive layer 22 can be more reliably maintained at the same potential.

Further, in the shield printed circuit board 1 of the present embodiment, the printed circuit board 10 further includes: a base member 12 on which the grounding circuit pattern 14 is formed, and an insulating film 11 which is provided on the base member 12 and covers the grounding circuit pattern 14. A hole portion 40 for exposing the partial grounding circuit pattern 14 is formed in the insulating film 11. The conductive layer 22 of the shielding film 20 is disposed on the conductive material 23 and contacts the conductive material 23, wherein the conductive material 23 is disposed on the insulating layer. 11 is filled in and filled in the hole portion 40.

According to the above configuration, the potential of the conductive layer 22 of the shield film 20 and the potential of the ground circuit pattern 14 can be made equal by the conductive material 23, and the conductive material 23 can be filled in the hole portion 40 formed in the insulating film 11. Therefore, it is not necessary to intentionally connect the external grounding member in order to make the potential of the conductive layer 22 at the ground potential.

Further, in the shield printed circuit board 1 of the present embodiment, the insulating layer 21 of the shielding film 20 is applied onto the conductive layer 22.

According to the above configuration, since the insulating layer 21 of the shielding film 20 is applied to the conductive layer, it can be made thinner than the film-shaped insulating layer 21, for example, and the conductive particles 32 protruding from the conductive bonding agent 30 can be easily broken. The insulating layer 21 is in contact with the conductive layer 22.

Further, in the shield printed circuit board 1 of the present embodiment, the reinforcing member 35 is formed of a stainless steel material.

According to the above configuration, since the stainless steel material has hardness suitable for reinforcement and excellent corrosion resistance, it is possible to more effectively reinforce the mounting portion of the electronic component 50 and provide a shielding effect to the mounting portion.

Further, in the present embodiment, the reinforcing member 35 may be further connected to an external grounding member that maintains the same potential as the grounding circuit pattern 14. In other words, the grounding member having the same potential as the grounding circuit pattern 14 may be separately prepared externally, and the reinforcing member 35 may be further connected to the grounding member by using a wiring or the like. According to this, the reinforcing member 32 is kept at the same potential as the grounding circuit pattern 14 by the conductive particles 32 included in the conductive bonding agent 30, and can be held at the same potential by the external grounding member and the grounding circuit pattern 14. Therefore, the shielding effect can be further improved.

(Manufacturing method of shield printed circuit board 1)

Next, a method of manufacturing the shield printed circuit board 1 of the present embodiment will be described with reference to FIGS. 2 and 3. As shown in FIG. 2 and FIG. 3, the manufacturing method of the shield printed circuit board 1 of the present embodiment includes a hole forming step of forming a hole portion 40 in the insulating film 11 of the printed circuit board 10; a shielding film bonding step in printing A shielding film 20 is disposed on the upper surface of the circuit board 10; a peeling layer peeling step is performed to peel off the uppermost peeling layer 28 located on the shielding film 20; and a conductive bonding agent bonding step is performed to bond the conductive property on the upper surface of the insulating layer 21 of the shielding film 20. The bonding agent 30; the reinforcing member bonding step of bonding the reinforcing member 35 to the conductive bonding agent 30; and the electronic component connecting step of connecting the electronic component 50 at a position opposite to the reinforcing member 35 on the lower surface of the printed circuit board 10.

Hereinafter, each step will be specifically described. As shown in FIG. 2(a), in the hole forming step, the printed circuit board 10 is first prepared. Then, the hole portion 40 is formed by laser processing the insulating film 11 of the printed circuit board 10 and the bonding layer 13. By this step, a partial region of the grounding circuit pattern 14 selected from a plurality of signal circuit patterns and a grounding circuit pattern or the like is exposed through the hole portion 40.

Next, as shown in FIG. 2(b), in the mask film bonding step, the shielding film 20 is bonded on the insulating film 11 of the printed circuit board 10. In the bonding process, the printed circuit board 10 and the shielding film 20 are press-bonded in the vertical direction by the press P while the conductive material 23 of the shielding film 20 is heated by the heater h. Thereby, the conductive material 23 of the shielding film 20 is softened by the heating of the heater h, and is bonded to the insulating film 11 by the pressure applied by the press P, and is filled in the hole portion 40. Then, the conductive material 23 filled in the hole portion 40 is quickly brought into contact with the ground circuit pattern 14. By this step, the shielding film 20 is provided on the insulating film 11 of the printed circuit board 10, and the conductive layer 22 of the shielding film 20 and the grounding circuit pattern 14 are electrically connected by the conductive material 23. Thereby, the conductive layer 22 of the shielding film 20 and the grounding circuit pattern 14 are kept at the same potential, and noise such as electromagnetic waves 90a from the outside can be shielded by the shielding film 20.

Next, as shown in FIG. 2(c), the uppermost peeling layer 28 previously provided on the shielding film 20 is peeled off in the peeling layer peeling step.

Next, as shown in FIG. 3(d), in the conductive bonding agent bonding step, the conductive bonding agent 30 is bonded to the insulating layer 21 of the shielding film 20. Further, in this step, the conductive bonding agent 30 is temporarily bonded to the insulating layer 21.

Next, as shown in FIG. 3(e), in the reinforcing member joining step, the reinforcing member 35 is joined to the conductive bonding agent 30. In the bonding process, while the conductive bonding agent 30 is heated by the heater h, the shielding film 20 and the reinforcing member 35 provided on the printed circuit board 10 are pressed by the presser P through the cushioning material 60 in the vertical direction. Thereby, the bonding agent 31 of the conductive bonding agent 30 is softened by the heating of the heater h, and the conductive particles 32 protrude from the bonding agent 31 by the pressure applied by the press P. Further, the conductive particles 32 protruding from the conductive bonding agent 30 break through the insulating layer 21 which is softened by the heating of the heater h by the pressure applied by the press P, and are quickly brought into contact with the conductive layer 22. Further, the heating temperature of the heater h is 150 ° C to 190 ° C, and the pressure of the press P is 2 MPa to 5 MPa. Further, the press P is pressurized for 5 minutes to 60 minutes. By this step, the reinforcing member 35 is provided on the shielding film 20, and the reinforcing member 35 and the conductive layer 22 of the shielding film 20 are electrically connected by the conductive particles 32. Thereby, the reinforcing member 35 and the conductive layer 22 and the grounding circuit pattern 14 are kept at the same potential, and the reinforcing member 35 can also have a shielding effect.

Finally, as shown in FIG. 3(f), in the electronic component connecting step, the electronic component 50 is connected to the mounting portion of the lower surface (the lower surface in the drawing) of the printed circuit board 10. At this time, the conductive layer 22 of the shield film 20 is disposed on the upper surface (upper side surface in the drawing) of the printed circuit board 10 and the conductive layer 22 covers a part or all of the region opposed to the mounting portion of the electronic component 50. Thereby, the electromagnetic wave 90b radiated from the mounting portion of the electronic component 50 from the outside can be shielded by the shielding film 20. In addition, a reinforcing member 35 is provided on the upper surface (upper side surface in the drawing) of the shielding film 20 and is disposed at a position opposite to the mounting portion of the electronic component 50. Thereby, the electromagnetic wave 90b radiated from the mounting portion of the electronic component 50 by the outside can be more reliably shielded by the shielding effect of the reinforcing member 35.

Further, in the conductive bonding agent bonding step shown in FIG. 3(d) and the reinforcing member bonding step shown in FIG. 3(e), the conductive bonding agent 30 is first attached to the insulating layer 21, and then the reinforcing member 35 is applied. Bonded to the conductive bonding agent 30. It is also possible to bond the reinforcing member 35 and the conductive bonding agent 30 first, and then attach the bonding body to the insulating layer 21. However, the adhesion of the conductive bonding agent 30 to the insulating layer 21 is better than that of bonding the conductive bonding agent 30 to the reinforcing member 35. Therefore, the manufacturing method of the present embodiment is easy to handle and easy to handle. Manufacturing.

(Examples and Comparative Examples)

Next, the present invention will be specifically described using the embodiment and comparative example of the shielded printed circuit board 1 of the present embodiment. The details of the examples and comparative examples and the experimental results are shown in FIG.

As shown in FIG. 4, in Embodiments 1 to 5 and Comparative Examples 1 and 2, a shield printed circuit board having the same structure as that of the shield printed circuit board 1 of the embodiment of the present invention shown in FIG. 1 was used, and the use in Comparative Example 3 was used. A shield printed circuit board having the same structure as the conventional shield printed circuit board 100 shown in FIG. More specifically, in the connection form between the reinforcing member and the grounding circuit pattern, the first to fifth embodiments and the comparative examples 1 and 2 have the same connection form as the shield printed circuit board 1 of the present embodiment, and only the comparative example 3 It has the same connection form as the conventional shield printed circuit board 100. Here, in the printed circuit boards 10 and 110 used in the embodiments and the comparative examples, the thickness of the base members 12 and 112 is 25 μm, and the thickness of the ground circuit patterns 14, 114 and 115 is 18 μm, and the bonding layers 13 and 113 are formed. The thickness was 25 μm, and the thickness of the insulating films 11, 111 was 12 μm. Further, in the shielding films 20 and 120 used in the examples and the comparative examples, the thickness of the conductive materials 23 and 123 was 10 μm, the thickness of the conductive layers 22 and 122 was 0.1 μm, and the thickness of the insulating layers 21 and 121 was 5 μm. Further, the reinforcing members 35, 135 were made of a nickel-plated stainless steel material having conductivity and a thickness of 0.2 mm.

Further, in Examples 1 to 5 and Comparative Examples 1 and 2, the thickness of the conductive bonding agent 30 in which the reinforcing member 35 was bonded to the insulating layer 21 was 10 μm, and the average of the conductive particles 32 was separately provided as shown in FIG. 4 . Particle size. Further, the average particle diameter variation of the conductive particles 32 of the examples was within ±5 μm. For example, in the first embodiment, the average particle diameter of the conductive particles 32 is 5 μm, and the thickness of the conductive bonding agent 30 and the conductive particles 32 in the state where the reinforcing member 35 and the insulating layer 21 are joined is 10 μm. In the first embodiment, since the average particle diameter (5 μm) of the conductive particles 32 is smaller than the thickness (10 μm) of the conductive bonding agent 30, the conductive particles 32 exist in the form of being buried in the conductive bonding agent 30. The thickness (10 μm) in the joined state is also the same as the thickness of the conductive bonding agent 30. Further, in the first embodiment, since the particle diameter of the conductive particles 32 is at most 10 μm even when the variation is considered, the conductive particles 32 are present in the form of the conductive bonding agent 30. In the second embodiment, the conductive particles 32 have an average particle diameter of 10 μm, and the conductive bonding agent 30 and the conductive particles 32 have a thickness of 10 μm in a state where the reinforcing member 35 and the insulating layer 21 are joined to each other. In the second embodiment, the average particle diameter of the conductive particles 32 (15 μm in consideration of the variation) is larger than the thickness (10 μm) of the conductive bonding agent 30, and the conductive particles 32 protrude from the conductive bonding agent 30. The length (5 μm) is the same as the thickness (5 μm) of the insulating layer 21. Therefore, when the variation in the average particle diameter of the conductive particles 32 is considered, the conductive particles 32 protruding from the conductive bonding agent 30 just break through the insulating layer 21 and come into contact with the conductive layer 22 therebelow.

Further, as shown in FIG. 4, the conductive particles 32 of the conductive bonding agent 30 in the first to fifth embodiments have a spherical shape. Further, in Comparative Example 1, the shape of the conductive particles 32 of the conductive bonding agent 30 was a sheet shape, and in the comparative example 2, the shape of the conductive particles 32 of the conductive bonding agent 30 was a dendritic shape. Further, in Comparative Example 3, the shape of the conductive particles of the conductive bonding agent 130 was set to be dendritic. Further, the amounts of the conductive particles in all of the examples and the comparative examples were uniformly 50% by weight.

The connection resistance between the reinforcing member and the grounding circuit pattern was measured using the examples and comparative examples set as described above. Further, a comprehensive evaluation was made in conjunction with the measured value of the measured connection resistance and the result of judging the reflow resistance in the reflow step, in which the heating temperature was about 260 °C. Here, the measurement value of the connection resistance between the reinforcing member and the grounding circuit pattern is set to a value of "○" when it is less than 0.5 Ω, and "△" when it is 0.5 Ω or more and less than 10.0 Ω. When it is greater than or equal to 10.0 Ω, it is “×”. In addition, regarding the reflow resistance, it is judged whether it is "○", "△", and "X" according to electrical detection such as appearance inspection and shielding detection after mounting.

As a result, in the comparative example 3, in the case of the reflow resistance, expansion occurred due to the occurrence of voids, and it was judged to be unacceptable by the appearance inspection or the like, that is, "x". The reason for this is considered to be that the connection form between the reinforcing member and the grounding circuit pattern is the same as that of the conventional shield printed wiring board 100 shown in FIG. 5, and therefore, the conductive bonding agent 130 is used. A gap is formed in the connection portion with the grounding circuit pattern 115. In other words, in the conventional shield printed wiring board 100, since the connection portion between the reinforcing member 135 and the grounding circuit pattern 115 is sandwiched by a hard material, the conductive bonding agent is applied when the strong member 135 is attached. 130 does not fully meet the steps of the hole portion 160. As a result, voids 160a and 160b are formed in the joint portion between the conductive bonding agent 130 and the grounding circuit pattern 115, and the void is expanded by the heating of the reflow step, thereby causing defects such as poor appearance and lack of shielding effect. . Further, in the fifth embodiment, since a certain number of voids occurred, it was judged as "Δ" in the appearance detection or the like. In the case of the fifth embodiment, the average particle diameter of the conductive particles 32 is 30 μm, and the average particle diameter of the conductive particles 32 is excessively large with respect to the thickness of the conductive bonding agent 30 and the insulating layer 21, so that it is considered that the average particle diameter of the conductive particles 32 is too large. The gap between the conductive bonding agent 30 and the insulating layer 21 is large, so that some voids may occur.

On the other hand, in the first to fourth embodiments and the first and second embodiments, the connection form between the reinforcing member and the grounding circuit pattern is the same as that of the shielded printed circuit board 1 of the present embodiment, and does not exist. When the average particle diameter of the conductive particles 32 is too large, defects such as Comparative Example 3 or Example 5 do not exist, and the reflow resistance satisfies the acceptance criteria marked "○".

Further, in the connection resistance between the reinforcing member and the grounding circuit pattern, Examples 2 to 5 and Comparative Example 3 satisfy the "○" standard, Example 1 is "Δ", and Comparative Examples 1 and 2 are "X". The reason for this is considered to be that the conductive particles in the comparative examples 1 and 2 have a sheet shape or a dendritic shape. Therefore, the insulating layer 21 cannot be broken due to the inclined state of the conductive particles, and the reinforcing member 35 cannot be maintained at the ground potential. Further, in the first embodiment, the average particle diameter of the conductive particles 32 is the same as or smaller than the thickness of the conductive bonding agent 30 in consideration of variations in the presence of the conductive particles 32. Therefore, the conductive particles 32 are The conductive bonding agent 30 protrudes less, and thus it is difficult to contact the conductive layer 22.

On the other hand, in the second to fifth embodiments, the average particle diameter of the conductive particles 32 is appropriate with respect to the thickness of the conductive bonding agent 30 and the thickness of the insulating layer 21, and therefore, the conduction state of the reinforcing member 35 and the conductive layer 22 is made. stable. As a result, the connection resistance between the reinforcing member 35 and the grounding circuit pattern 14 can be maintained at 0.5 Ω or less. Further, in the comparative example 3, the gaps 160a and 160b are formed in the connection portion between the conductive bonding agent 130 and the grounding circuit pattern 115, but the conduction state of the reinforcing member 135 and the grounding circuit pattern 115 passes through the dendritic conductivity. The bonding agent 130 is held, so that the connection resistance between the reinforcing member 135 and the grounding circuit pattern 115 can be maintained at 0.5 Ω or less.

According to the above experimental results, if the determination of the connection resistance of the reinforcing member and the grounding circuit pattern and the determination of the backflow resistance are comprehensively evaluated by "○", "△", and "X", the evaluation results are as follows: Example 2 4 to "○", Examples 1 and 5 are "Δ", and Comparative Examples 1 to 3 are "X". According to the results, when the connection form of the reinforcing member 35 and the grounding circuit pattern 14 in the shield printed wiring board 1 of the present embodiment is used, the reflow resistance satisfies the acceptance criteria of "Δ" or more. Further, according to the results, in the shield printed circuit board 1 of the present embodiment, when the conductive particles 32 protruding from the conductive bonding agent 30 are in contact with the conductive layer 22, the connection resistance of the reinforcing member and the grounding circuit pattern is satisfied. Eligibility criteria above "△". Further, according to the results, it is understood that the average particle diameter of the conductive particles 32 is appropriate as compared with the thickness of the conductive bonding agent 30 and the insulating layer 21, and the gap generated between the conductive bonding agent 30 and the insulating layer 21 is considered even if the deviation is considered. In the case of not exceeding 10 μm (in the case of Example 4), the connection resistance and the reflow resistance were also good results, and the acceptance criteria of "○" were satisfied in the comprehensive evaluation.

The embodiments of the present invention have been described above. Further, the present invention is not limited to the above embodiment.

For example, in the shield printed circuit board 1 of the present embodiment, the protruding portion of the conductive particles 32 protruding from the conductive bonding agent 30 breaks through the insulating layer 21, so that the reinforcing member 35 contacts the conductive layer having the same potential as the grounding circuit pattern 14. twenty two. Other methods can also be used to maintain the stiffening member 35 and the conductive layer 22 at an equal potential. For example, a plurality of holes for exposing the conductive layer 22 to the surface of the insulating layer 21 may be formed by laser or the like, and a conductive bonding agent containing dendritic conductive particles may be attached thereto, thereby making conductivity The particles flow into the hole portion to bring the conductive particles into contact with the conductive layer 22. Thereby, the reinforcing member 35 and the conductive layer 22 can be held at the same potential by the conductive bonding agent, and the conductive bonding agent includes the dendritic conductive particles filled in the hole portion.

The embodiments of the present invention have been described above, but the embodiments are merely illustrative, and the present invention is not particularly limited, and appropriate design changes can be made to specific configurations and the like. In addition, the functions and effects described in the embodiments are merely illustrative of the optimal effects and effects produced by the present invention, and the actions and effects produced by the present invention are not limited to the description of the embodiments.

Industrial availability

The invention can be applied to a shielded printed circuit board used in electronic devices such as portable telephones and computers.

1. . . Shielded printed circuit board

10. . . A printed circuit board

11. . . Insulating film

12. . . Base part

13. . . Adhesive layer

14. . . Grounding circuit pattern

20. . . Shielding film

twenty one. . . Insulation

twenty two. . . Conductive layer

twenty three. . . Conductive material

30. . . Conductive bonding agent

31. . . Adhesive

32. . . Conductive particles

35. . . Reinforcement

40. . . Hole

50. . . Electronic components

90a. . . Electromagnetic wave

90b. . . Electromagnetic wave

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial cross-sectional view showing a shield printed circuit board of the present embodiment.

Fig. 2 (a) is a view showing a step of forming a hole portion in the method of manufacturing the shield printed wiring board of the embodiment. Fig. 2 (b) is a view showing a step of joining the shielding films in the method of manufacturing the shield printed wiring board of the present embodiment. Fig. 2 (c) is a view showing a peeling layer peeling step of the shielding film in the method of manufacturing the shield printed wiring board of the embodiment.

Fig. 3 (d) is a view showing a step of bonding a conductive bonding agent in the method of manufacturing a shield printed wiring board of the present embodiment. Fig. 3 (e) is a view showing a step of joining the reinforcing members in the method of manufacturing the shield printed wiring board of the embodiment. Fig. 3 (f) is a view showing a step of connecting electronic components to which electronic components are connected in the shield printed circuit board of the embodiment.

Fig. 4 is a view showing experimental results obtained by using the examples and comparative examples of the shield printed circuit board of the present embodiment.

Figure 5 is a partial cross-sectional view showing a conventional shield printed circuit board.

1. . . Shielded printed circuit board

10. . . A printed circuit board

11. . . Insulating film

12. . . Base part

13. . . Adhesive layer

14. . . Grounding circuit pattern

20. . . Shielding film

twenty one. . . Insulation

twenty two. . . Conductive layer

twenty three. . . Conductive material

30. . . Conductive bonding agent

31. . . Adhesive

32. . . Conductive particles

35. . . Reinforcement

40. . . Hole

50. . . Electronic components

90a. . . Electromagnetic wave

90b. . . Electromagnetic wave

Claims (5)

A shield printed circuit board comprising: a printed circuit board comprising: a base member formed with a grounding circuit pattern; and an insulating film disposed on the base member and covering the grounding circuit pattern, and disposed on the base member An electronic component is connected to the mounting portion of the lower surface; the shielding film is disposed on the printed circuit board, and the shielding film includes a conductive layer disposed on the upper surface of the printed circuit board at a potential equal to the grounding circuit pattern and Covering a part or all of a region facing the mounting portion; and an insulating layer disposed on the conductive layer; and a reinforcing member having electrical conductivity and disposed on the shielding film at a region opposing the mounting portion, wherein The reinforcing member is bonded to the insulating layer by a conductive bonding agent, wherein the conductive bonding agent includes spherical conductive particles, and the insulating layer has a layer thickness smaller than that of the conductive particles in the conductive bonding agent and the insulating layer. The protruding length protruding from the above-mentioned conductive bonding agent in the joined state The conductive particles are in contact with the conductive layer in a state where the conductive adhesive and bonded to the insulating layer. The shield printed circuit board according to claim 1, wherein the reinforcing member is further connected to an external grounding member, wherein the external grounding member and the grounding circuit pattern are kept at the same potential. The shield printed circuit board according to claim 1, wherein the insulating layer of the shielding film is coated on the conductive layer. The shield printed circuit board according to claim 2, wherein the insulating layer of the shielding film is coated on the conductive layer. The shield printed circuit board according to any one of claims 1 to 4, wherein the reinforcing member is formed of a stainless steel material.