JP2015191981A - Printed wiring board connection structure, electronic device, and printed wiring board connection method - Google Patents

Abstract

An object of the present invention is to provide a printed wiring board connection structure in which the adhesive strength between an anisotropic conductive adhesive layer and a connection region can be obtained easily and reliably and the production efficiency is high. The present invention relates to an anisotropic conductive adhesive in a connecting region where a pair of conductive patterns face each other in a pair of printed wiring boards having a base film having insulating properties and a conductive pattern laminated on one surface side thereof. It is a connection structure of a printed wiring board electrically connected through a layer, and has a convex portion on the opposite side of the connection region of at least one base film of the pair of printed wiring boards. The said convex part is good to be formed from a metal material. The region where the convex portion is formed is preferably smaller than the connection region. The base film of the printed wiring board having the convex portion may be recessed in the facing direction in the connection region. One of the pair of printed wiring boards may be a single printed wiring board and the other may be a plurality of printed wiring boards. [Selection] Figure 1

Description

  The present invention relates to a printed wiring board connection structure, an electronic device, and a printed wiring board connection method.

  In the mounting method in which the connection terminals of a plurality of printed wiring boards are electrically connected to each other, a high-density mounting method corresponding to the increasingly smaller and thinner devices is required. One such high-density mounting method is a method using an anisotropic conductive material (anisotropic conductive adhesive). Such anisotropic conductive adhesive presses the heating body against the printed wiring board during thermocompression bonding and is compressed in the thickness direction by heating and pressurization during thermocompression bonding so that the conductive particles contact each other. Thus, a conductive path in the thickness direction is formed. On the other hand, since the state of high insulation resistance is maintained in the plane direction of the anisotropic conductive material, a large number of connection terminals can be electrically connected independently.

  In such an electrical connection using an anisotropic conductive adhesive, pressure is applied. Therefore, if the pressure is high, the printed wiring board may be deformed or damaged. For this reason, the device which lowers the pressure at the time of pressurization is made (for example, refer to JP, 2012-160765, A).

JP 2012-160765 A

  When the pressure at the time of pressurization is lowered as in the above prior art, if the applied pressure varies between the plurality of connection terminals, the anisotropic conductive adhesive layer and the connection terminal at the connection terminal where the applied pressure is low There is a risk that the adhesive strength of the resin is insufficient and high connection reliability cannot be obtained. In order to avoid this, it is necessary to accurately superimpose the heating body and the printed wiring board and to overlap the connection terminals of the printed wiring board to suppress the occurrence of variations in applied pressure. However, in this case, it takes time to superimpose, and production efficiency may be deteriorated. In particular, when a plurality of printed wiring boards are connected to one printed wiring board, the accuracy of superposition is further required to collectively connect with one heating body, and further deterioration in production efficiency is inevitable.

  The present invention has been made in view of such inconveniences, and has a printed wiring board connection structure in which the adhesive strength between the anisotropic conductive adhesive layer and the connection region can be obtained easily and reliably, and the production efficiency is high. The purpose is to provide.

  In the present invention, an anisotropic conductive adhesive layer is interposed in a connection region where a pair of conductive patterns face each other in a pair of printed wiring boards having a base film having insulating properties and a conductive pattern laminated on one surface side thereof. It is a connection structure of a printed wiring board that is electrically connected, and has a convex portion on the side opposite to the connection region of at least one base film of the pair of printed wiring boards.

  Another invention made in order to solve the above-described problem is that a pair of printed wiring boards having an insulating base film and a conductive pattern laminated on one side of the base film are connected to each other in a connection region where the pair of conductive patterns face each other. A method of connecting a printed wiring board that is electrically connected through an anisotropic conductive adhesive layer, the step of overlapping the connection region of the pair of printed wiring boards through an anisotropic conductive adhesive film, and A step of thermocompression bonding a pair of printed wiring boards and an anisotropic conductive adhesive film in a connection region, and having a convex portion on the opposite side of the connection region of at least one base film of the pair of printed wiring boards. The convex portion is pressed with a heating body.

  In the printed wiring board connection structure of the present invention, the adhesive strength between the anisotropic conductive adhesive layer and the connection region can be obtained easily and reliably, and the production efficiency is high. Therefore, the connection structure of the printed wiring board can electrically connect the printed wiring board efficiently with high connection reliability. Moreover, since the electronic device of the present invention includes the connection structure for the printed wiring board, it has high connection reliability and high production efficiency.

FIG. 1 is a schematic end view (cut surface is a surface perpendicular to a base film) showing an embodiment of a printed wiring board connection structure of the present invention. FIG. 2A is a schematic end view (the cut surface is a surface perpendicular to the base film) for explaining the connection method of the printed wiring board of the present invention, and is anisotropic on the surface of the connection terminal of the first printed wiring board. The state which mounted the electroconductive adhesive film is shown. FIG. 2B is a schematic end view for explaining the connection method of the printed wiring board of the present invention (the cut surface is a surface perpendicular to the base film), and the first printed wiring board of the anisotropic conductive adhesive film; The state which mounted the 2nd printed wiring board in the surface of the other side is shown. FIG. 2C is a schematic end view (a cut surface is a surface perpendicular to the base film) for explaining the connection method of the printed wiring board according to the present invention, and the first print is interposed through the anisotropic conductive adhesive layer. The state which is crimping | bonding the connection terminal of a wiring board and the connection terminal of a 2nd printed wiring board is shown.

[Description of Embodiment of the Invention]
In the present invention, an anisotropic conductive adhesive layer is interposed in a connection region where a pair of conductive patterns face each other in a pair of printed wiring boards having a base film having insulating properties and a conductive pattern laminated on one surface side thereof. It is a connection structure of a printed wiring board that is electrically connected, and has a convex portion on the side opposite to the connection region of at least one base film of the pair of printed wiring boards.

  Since the connection structure of the printed wiring board of the present invention has a convex portion on the opposite side of the connection region of at least one base film, the pressure applied to the connection region can be increased by pressurizing the convex portion. For this reason, the connection structure of the said printed wiring board can obtain easily and reliably the high adhesive strength of an anisotropic conductive adhesive layer and a connection area | region, without performing exact superimposition with a heating body at the time of pressurization. Therefore, the connection structure of the printed wiring board can electrically connect the printed wiring board efficiently with high connection reliability.

  The said convex part is good to be formed from a metal material. Thus, the convex part is formed of a metal material, so that the convex part is not easily deformed during pressurization, and the pressure applied to the connection region can be reliably increased.

  The region where the convex portion is formed is preferably smaller than the connection region. Thus, since the area | region where the said convex part is formed is smaller than the said connection area | region, the pressure concerning a connection area | region can further be raised.

  The base film of the printed wiring board having the convex portion may be recessed in the facing direction in the connection region. Thus, since the base film of the printed wiring board which has the said convex part is dented in the opposing direction in the connection area | region, the connection area | region which opposes adjoins and adhesive strength further increases.

  The average thickness of the convex portions is the total average thickness of the pair of conductive patterns facing each other in the connection region from the total average thickness of one or more films disposed between the pair of base films in the pair of printed wiring boards. It should be larger than the value obtained by subtracting the thickness. Thus, since the average thickness of the convex portion is larger than the above value, the region where the convex portion exists can be projected most in the region where the heating body abuts, so that the pressure applied to the connection region reliably. Can be high.

  The connection region may be a region where the connection terminals are provided in the pair of printed wiring boards. As described above, since the connection area is an area for arranging the connection terminals in the pair of printed wiring boards, the connection area can be regularly arranged, and the overlay through the anisotropic conductive adhesive film can be easily and reliably performed. It can be carried out.

  One of the pair of printed wiring boards may be a single printed wiring board and the other may be a plurality of printed wiring boards. As described above, one of the pair of printed wiring boards is a single printed wiring board and the other is a plurality of printed wiring boards, so that the plurality of printed wiring boards are connected together by one heating body. Production efficiency can be increased.

  The present invention includes an electronic device having a connection structure for the printed wiring board. Since the electronic device includes the printed wiring board connection structure, the production efficiency is high. In addition, the electronic device has high adhesive strength between the anisotropic conductive adhesive layer and the connection terminal, and has high connection reliability.

  Another invention made in order to solve the above-described problem is that a pair of printed wiring boards having an insulating base film and a conductive pattern laminated on one side of the base film are connected to each other in a connection region where the pair of conductive patterns face each other. A method of connecting a printed wiring board that is electrically connected through an anisotropic conductive adhesive layer, the step of overlapping the connection region of the pair of printed wiring boards through an anisotropic conductive adhesive film, and A step of thermocompression bonding a pair of printed wiring boards and an anisotropic conductive adhesive film in a connection region, and having a convex portion on the opposite side of the connection region of at least one base film of the pair of printed wiring boards. The convex portion is pressed with a heating body.

  Since the connection method of the printed wiring board has a convex portion on the opposite side of the connection region of at least one base film, the pressure applied to the connection region can be increased by pressurizing the convex portion. For this reason, the connection structure of the said printed wiring board can obtain easily and reliably the high adhesive strength of an anisotropic conductive adhesive layer and a connection area | region, without performing exact superimposition with a heating body at the time of pressurization. Moreover, the connection method of the said printed wiring board can connect several printed wiring boards collectively with one heating body, and its production efficiency is good.

  Here, “one or a plurality of films disposed between a pair of base films in a pair of printed wiring boards” is a concept including a synthetic resin layer constituting a printed wiring board such as a solder resist in addition to a film-like layer. It is.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of a printed wiring board connection structure, an electronic device, and a printed wiring board connection method according to the present invention will be described in detail with reference to the drawings.

[First embodiment]
The connection structure of the printed wiring board shown in FIG. 1 is a pair of printed wiring boards 1 and 2 having a base film 1a and 2a having insulation properties and conductive patterns 1b and 2b laminated on one surface side thereof (first In the printed wiring board 1 and the second printed wiring board 2), the pair of conductive patterns 1b and 2b are electrically connected via the anisotropic conductive adhesive layer 3 at a plurality of facing connection regions. Moreover, the connection structure of the said printed wiring board has the convex part 4 on the opposite side to the said connection area | region of the base film 2b of said 2nd printed wiring board 2. FIG. In the plurality of connection regions, connection terminals 1c and 2c are disposed as part of the conductive patterns 1b and 2b, respectively, and the connection regions are regions for connection terminals 1c and 2c in a pair of printed wiring boards. .

<Printed wiring board>
The pair of printed wiring boards 1 and 2 includes insulating base films 1a and 2a and conductive patterns 1b and 2b formed on one surface side of the base films 1a and 2a. Further, portions of the conductive patterns 1b, 2b other than the plurality of connection terminals 1c, 2c (for example, wiring portions) are covered with cover lays 1d, 2d. The second printed wiring board 2 has flexibility. On the other hand, the first printed wiring board 1 may be either flexible or non-flexible.

(Base film)
The said base films 1b and 2b are comprised from the sheet-like member which has insulation. Although it does not specifically limit as this base film 1b, 2b, For example, a resin film is employable. As a material for this resin film, for example, epoxy, polyimide, polyethylene terephthalate and the like are preferably used. Further, when the first printed wiring board 1 is not flexible, the base film 1b can be, for example, epoxy glass.

  The base film 2a of the second printed wiring board 2 is recessed in the direction of the base film 1a of the first printed wiring board 1, which is the opposite direction in the connection region where the connection terminals 2c are disposed. Thus, since the base film 2a of the 2nd printed wiring board 2 which has the said convex part 4 is dented in the opposing direction in a connection area | region, the connection area which opposes adjoins and adhesive strength further increases.

  Although the average thickness of the said base films 1a and 2a is not specifically limited, As a minimum of the average thickness of the said base films 1a and 2a, 5 micrometers is preferable and 10 micrometers is more preferable. Moreover, as an upper limit of the average thickness of the said base films 1a and 2a, 300 micrometers is preferable and 50 micrometers is more preferable. When the average thickness of the base films 1a and 2a is less than the lower limit, the strength of the base films 1a and 2a may be insufficient. On the other hand, when the average thickness of the base films 1a and 2a exceeds the above upper limit, the connection structure of the printed wiring board becomes unnecessarily thick, which may be contrary to downsizing and thinning of the device. Moreover, when using what does not have flexibility as the base film 1b of said 1st printed wiring board 1, the average thickness of the said base films 1b and 2b can be 100 micrometers or more and 2 mm or less, for example.

(Conductive pattern)
The conductive patterns 1b and 2b are made of metal, and a plurality of connection terminals 1c and 2c for electrically connecting a connected body such as a mounting component or another printed wiring board, and wiring for constituting an electric circuit Etc. Among these, plating layers such as a gold plating layer and other noble metal plating layers (a silver plating layer, a platinum plating layer, a palladium plating layer, etc.) may be provided on the surfaces (exposed surfaces) of the connection terminals 1c and 2c.

  The conductive patterns 1b and 2b are formed in a desired planar shape (pattern) by etching, for example, a copper thin film laminated on one surface side of the base films 1a and 2a.

(Connecting terminal)
The average thickness of the connection terminals 1c and 2c is not particularly limited, but the lower limit of the average thickness of the connection terminals 1c and 2c is preferably 2 μm, and more preferably 5 μm. The upper limit of the average thickness of the connection terminals 1c and 2c is preferably 50 μm, and more preferably 40 μm. When the average thickness of the connection terminals 1c and 2c is less than the lower limit, the connection terminals 1c and 2c may be deformed during pressurization, and the anisotropic conductive adhesive layer and the connection terminals may not be sufficiently bonded. On the other hand, when the average thickness of the connection terminals 1c and 2c exceeds the upper limit, the connection structure of the printed wiring board is unnecessarily increased, which may be contrary to downsizing and thinning of the device. The other portions (for example, wiring portions) other than the connection terminals 1c and 2c of the conductive patterns 1b and 2b are provided with the same thickness as the connection terminals 1c and 2c. It is also an item that can be appropriately changed in design.

  Further, the shape and dimensions of the connection terminals 1c and 2c in plan view are not particularly limited, and the design can be appropriately changed depending on the product using the printed wiring boards 1 and 2 and the specifications of the mounted components. .

(Coverlay)
The coverlays 1d and 2d are films that have an insulating function and an adhesive function, and are laminated on one surface side of the conductive patterns 1b and 2b and the base films 1a and 2a. As the coverlays 1d and 2d, for example, a two-layer film having an insulating layer and an adhesive layer can be used.

  When the cover layers 1d and 2d have a two-layer structure of an insulating layer and an adhesive layer, the material of the insulating layer is not particularly limited, but the same resin film as that constituting the base films 1a and 2a is used. Can be used. As a minimum of average thickness of an insulating layer of coverlays 1d and 2d, 5 micrometers is preferred and 10 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the insulating layers of the coverlays 1d and 2d is preferably 60 μm, and more preferably 40 μm. If the average thickness of the insulating layers of the coverlays 1d and 2d is less than the above lower limit, the insulating property may be insufficient, and if the average thickness of the insulating layers of the coverlays 1d and 2d exceeds the above upper limit, it is flexible. There is a possibility that the flexibility of the printed wiring board 1 is insufficient.

  When the coverlays 1d and 2d have a two-layer structure of an insulating layer and an adhesive layer, the adhesive constituting the adhesive layer is not particularly limited, but has excellent flexibility and heat resistance. Examples of the adhesive include various resin adhesives such as nylon resin, epoxy resin, butyral resin, and acrylic resin. The average thickness of the adhesive layers of the coverlays 1d and 2d is not particularly limited, but is preferably 5 μm or more and 30 μm or less. If the average thickness of the adhesive layers of the coverlays 1d and 2d is less than the above lower limit, the adhesion may be insufficient, and if it exceeds the upper limit, the printed wiring boards 1 and 2 may be unnecessarily thick. .

  The coverlays 1d and 2d have openings. This opening becomes a region where the plurality of connection terminals 1c and 2c are exposed. Accordingly, the plurality of connection terminals 1c and 2c are surrounded by the coverlays 1d and 2d.

(Printed wiring board manufacturing method)
The method for manufacturing the printed wiring boards 1 and 2 includes, for example, a process of forming metal conductive patterns 1b and 2b having a plurality of connection terminals 1c and 2c (conductive pattern forming process) and a process of laminating a coverlay (coverlay). Laminating step).

  In the conductive pattern formation step, a conductive film 1b, 2b having a plurality of connection terminals 1c, 2c is obtained by processing a thin film made of metal on one side of the base films 1a, 2a and processing the thin film. Form. The method of laminating the metal thin film on the base films 1a and 2a is not particularly limited. For example, an adhesion method in which a metal foil is bonded with an adhesive, or a resin composition that is a material of the base films 1a and 2a on the metal foil. The casting method etc. which apply | coat an object can be used. The conductive patterns 1b and 2b can be formed by a conventionally known method. For example, the conductive patterns 1b and 2b can be formed by etching a desired portion of a metal thin film laminated on one surface side of the base films 1a and 2a. . Part of the conductive patterns 1a and 2a becomes the plurality of connection terminals 1c and 2c described above.

  In the cover lay stacking step, the cover lay is stacked so as to cover the conductive patterns 1b and 2b excluding the plurality of connection terminals 1c and 2c. The method for laminating the coverlay is not particularly limited, and for example, a known screen printing method or the like can be used.

<Convex>
The plurality of convex portions 4 are protrusions formed on the base film 2 a of the second printed wiring board 2 on the side opposite to the plurality of connection terminals 2 c. The convex portions 4 are arranged in a one-to-one relationship, one for each connection terminal.

  Although it does not specifically limit as a material which forms the said convex part 4, A metal, resin, a ceramic, etc. can be mentioned. Of these, metals are preferred. By forming the convex part 4 from a metal material, it becomes difficult to deform | transform a convex part at the time of pressurization, and the pressure concerning a connection terminal can be made high reliably. Although it does not specifically limit as a metal which forms the convex part 4, The thing similar to the metal which comprises the conductive pattern 2b, SUS used for a reinforcement board, etc. can be used. In the case of a double-sided printed wiring board, a part of the conductive pattern opposite to the connection terminal 2a may be used.

  The region where the convex portion 4 is formed is preferably smaller than the connection region where the connection terminal 2c is disposed. The upper limit of the ratio of the area of the region where the protrusions 4 are formed to the area of the connection terminal 2c in plan view is preferably 95%, more preferably 90%. Moreover, as a minimum of the said area ratio, 20% is preferable and 40% is more preferable. When the area ratio exceeds the upper limit, the pressure applied to the connection terminal 2c of the second printed wiring board 2 is insufficient, and the adhesive strength between the anisotropic conductive adhesive layer 3 and the connection terminals 1c and 2c may be insufficient. There is. On the other hand, when the area ratio is less than the lower limit, the pressure applied to the connection terminal 2c is locally increased, and the printed wiring board 2 may be deformed or damaged.

  A pair of the convex portions 4 facing each other in the connection region from the total average thickness of the coverlays 1d and 2d disposed between the pair of base films 1a and 2a in the pair of printed wiring boards 1 and 2 It may be larger than the value obtained by subtracting the total average thickness of the conductive patterns 1b and 2b. Thus, since the average thickness of the said convex part 4 is larger than the said value, since the area | region where a convex part exists can be protruded most within the area | region where a heating body contact | abuts, it starts on a connection area | region reliably. The pressure can be increased.

  The lower limit of the difference (average protrusion thickness) between the average thickness of the protrusions 4 and the value obtained by subtracting the total average thickness is preferably 5 μm, and more preferably 10 μm. Moreover, as an upper limit of the said average protrusion thickness, 50 micrometers is preferable and 30 micrometers is more preferable. When the average protrusion thickness is less than the lower limit, when the convex portion 4 is pressed by the heating body, the heating body contacts other than the convex portion 4 due to elastic deformation, and the pressure is not sufficiently applied to the convex portion 4. There is a fear. On the other hand, when the average protrusion thickness exceeds the upper limit, the connection structure of the printed wiring board becomes unnecessarily thick, which may be contrary to the downsizing and thinning of the device.

  Moreover, as a minimum of the average thickness of the said convex part 4, 20 micrometers is preferable and 30 micrometers is more preferable. As an upper limit of the average thickness of the said convex part 4, 150 micrometers is preferable and 100 micrometers is more preferable. When the average thickness of the convex portion 4 is less than the lower limit, the average protruding thickness is insufficient, and the pressure may not be sufficiently applied to the convex portion 4. On the other hand, when the average thickness of the convex part 4 exceeds the upper limit, the connection structure of the printed wiring board becomes unnecessarily thick, which may be contrary to downsizing and thinning of the device.

  Moreover, there may be other layers, such as a shield layer, between the said convex part 4 and the base film 2a, and the convex part 4 may be laminated | stacked directly on the base film 2a.

<Anisotropic conductive adhesive layer>
The anisotropic conductive adhesive layer 3 has an adhesive and a plurality of conductive particles dispersed in the adhesive. The anisotropic conductive adhesive layer 3 is a layer that allows electrical continuity only in one direction and does not allow electrical continuity in the other direction. Specifically, the anisotropic conductive adhesive layer 3 is a front-back direction of the connection structure of the printed wiring board. Electrical conduction is allowed, and planar electrical conduction is not allowed. The anisotropic conductive adhesive layer 3 can be formed using an anisotropic conductive adhesive such as a film or a paste.

  Although it does not specifically limit as said adhesive agent, For example, a thermoplastic resin and a thermosetting resin can be used. Specifically, examples of the thermoplastic resin include phenoxy resin, polyvinyl butyral, acrylic resin, and examples of the thermosetting resin include epoxy resin and acrylic resin. Moreover, when using an epoxy resin as an adhesive agent, the adhesive agent preferably contains a latent hardener as a hardener. When the adhesive contains a curing agent for accelerating the curing of the epoxy resin, a high adhesive force can be obtained. Examples of such latent curing agents include amines such as imidazoles, dicyandiamides, acid anhydrides, and phenols. Moreover, when using an acrylic resin as an adhesive agent, the said adhesive agent is good to contain a peroxide reaction initiator as a hardening | curing agent. When the adhesive contains the peroxide reaction initiator, the acrylic resin can be easily cured. Examples of such peroxide reaction initiators include dicumyl peroxide, propionitrile peroxide, and benzoyl peroxide.

  Moreover, as said electroconductive particle, what has the shape where the single spherical particle or the several spherical particle was connected in linear form can be used. Examples of the spherical particles include metal fine particles or metal-plated resin particles. Although it does not specifically limit as said metal, For example, nickel, copper, gold | metal | money, tin, solder etc. can be used. In addition, the plurality of spherical particles constituting the conductive particles having a shape connected in a straight chain may include a metal having magnetism. By including a metal having magnetism, it becomes easy to orient the conductive particles linearly using a magnetic field due to the magnetism of the metal itself. An example of such a metal having magnetism is nickel.

  The content of the conductive particles in the anisotropic conductive adhesive layer 3 is not particularly limited, and may be, for example, 0.01 volume% or more and 10 volume% or less.

<Advantages>
Since the connection structure of the printed wiring board has the convex part 4 on the opposite side to the connection area of the base film 2a of the second printed wiring board 2, the pressure applied to the connection area can be increased by pressurizing the convex part 4. Can be increased. For this reason, the connection structure of the printed wiring board can easily and reliably obtain a high adhesive strength between the anisotropic conductive adhesive layer 3 and the connection region without accurately overlapping with the heating body during pressurization. . Therefore, the connection structure of the printed wiring board can electrically connect the printed wiring board efficiently with high connection reliability. Further, since the connection area is an arrangement area of the connection terminals 1 c and 2 c in the pair of printed wiring boards 1 and 2, the connection area can be regularly arranged and overlapped via the anisotropic conductive adhesive film 3. Can be easily and reliably performed.

<Connection method of printed wiring board>
Next, with respect to the method of connecting the printed wiring boards, referring to FIGS. 2A, 2B and 2C, an example of connecting two first printed wiring boards and one second printed wiring board is used. However, it will be explained. The second printed wiring board has two sets of connection area groups, each corresponding to a connection area group of two first printed wiring boards.

  The method for connecting the printed wiring board includes a step of forming a convex portion on the opposite side of the base film connecting region of the second printed wiring board (convex portion forming step), and the connection terminals of the pair of printed wiring boards are anisotropic. A step of superposing via the conductive adhesive film (superposition step), and a step of thermocompression bonding the pair of printed wiring boards and the anisotropic conductive adhesive film in the connection region (thermocompression step).

  In the convex portion forming step, a plurality of convex portions 4 are formed on the side opposite to the connection region of the base film 2 b of the second printed wiring board 2. Although it does not specifically limit as a method of forming the convex part 4, For example, the method of sticking a metal plate is mentioned. Further, in a double-sided printed wiring board, a method of providing a convex portion 4 simultaneously with a conductive pattern by printing a conductive paste on the side opposite to the connection terminal 2c, or a metal foil for forming a conductive pattern on the side opposite to the connection terminal 2c The method of forming the convex part 4 at the time of an etching is mentioned.

  Next, in the superposition process, two first printed wiring boards 1 and one second printed wiring board 2 are superposed via an anisotropic conductive adhesive film. First, as shown in FIG. 2A, an anisotropic conductive adhesive film 30 is placed on the surface of the connection terminal 1 c of the first printed wiring board 1. Then, the anisotropic conductive adhesive film 30 is temporarily bonded to the surface of the connection terminal 1c by pressurizing the anisotropic conductive adhesive film 30 to the first printed wiring board 1 side while being heated to a predetermined temperature. To do. This temporary adhesion is performed on each of the two first printed wiring boards 1.

  Next, as shown in FIG. 2B, the connection terminal 2 c side of the second printed wiring board 2 faces the anisotropic conductive adhesive film 30, and the connection terminal 2 c and the connection terminal 1 c form the anisotropic conductive adhesive film 30. The two second printed wiring boards 2 are overlapped so as to be opposed to each other, and are overlapped on the surface opposite to the first printed wiring board 1 of the anisotropic conductive adhesive film 30.

  Finally, in the thermocompression bonding step, as shown in FIG. 2C, the first printed wiring board 1 and the second printed wiring board 2 are bonded with the anisotropic conductive adhesive film 30 heated to a predetermined temperature. Squeeze. Specifically, for example, using one heating body X heated to 100 ° C. or more and 300 ° C. or less, all the protrusions 4 formed on the second printed wiring board 2 via the cushion material Y are 1 MPa or more and 9 MPa. Press with pressure. Although it does not specifically limit as the heating body X, For example, the heat tool in which the material of the heater part was formed with aluminum nitride, an alumina, tungsten, molybdenum, silicon carbide etc. can be used. The material of the cushion material Y is not particularly limited, and examples thereof include silicon rubber and polytetrafluoroethylene (PTFE). Thus, the anisotropic conductive adhesive layer 3 is formed, and the connection terminals 1c of the two first printed wiring boards 1 and the connection terminals 2c of the second printed wiring board 2 are anisotropically conductive adhesive layers 3. The connection terminal 1c and the connection terminal 2c are electrically connected to each other at the same time.

<Advantages>
Since the printed wiring board has a convex portion 4 on the side opposite to the connection terminal 2c of the base film 2a, pressurizing the convex portion 4 can increase the pressure applied to the connection terminals 1c and 2c. it can. For this reason, the connection structure of the printed wiring board facilitates high adhesive strength between the anisotropic conductive adhesive layer 3 and the connection terminals 1c and 2c without accurate overlapping with the heating element X during pressurization. It is definitely obtained. Moreover, the connection method of the said printed wiring board can connect the two printed wiring boards 1 collectively with the one heating body X, and its production efficiency is good.

<Electronic equipment>
The electronic apparatus includes the connection structure for the printed wiring board. The electronic device has high production efficiency because the electronic device includes the connection structure for the printed wiring board. In addition, the electronic device has high adhesive strength between the anisotropic conductive adhesive layer and the connection terminal, and has high connection reliability.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  In the above embodiment, the printed wiring board in which one layer of the conductive pattern is laminated on one surface has been described as an example. However, the target of the connection method of the printed wiring board is not limited to this, and a multilayer The use of various types of printed wiring boards such as printed wiring boards and double-sided printed wiring boards is also a matter whose design can be changed as appropriate.

  Moreover, in the said embodiment, although the case where the connection area | region was a connection terminal was demonstrated as an example, other conductors, such as a land part, may be sufficient, for example.

  Moreover, in the said embodiment, although the method using an anisotropic conductive adhesive film was demonstrated as a method of electrically connecting a connection terminal, this invention is not limited to this. For example, a conductive adhesive in which conductive particles are contained in a paste adhesive may be employed. When using a paste-like conductive adhesive, the connection terminal is electrically connected by applying the conductive paste to the surface of the connection terminal by screen printing or the like and then heating and pressing the adhesive.

  Moreover, although the case where the conductive pattern portions other than the connection terminals are covered with the coverlay has been described in the above-described embodiment, the same effect can be obtained even if the conductive pattern portion is covered with another coating layer such as a solder resist.

  In the above embodiment, the case where one printed wiring board has a plurality of connection terminals and projections has been described, but this is the case where one printed wiring board has one connection terminal and projections. However, the same effect is obtained.

  Furthermore, in the said embodiment, although the connection method of the printed wiring board at the time of connecting two 1st printed wiring boards and one 2nd printed wiring board was demonstrated, three or more 1st printed wiring boards were connected. The printed wiring board and the second printed wiring board may be connected together. Also, one first printed wiring board and two or more second printed wiring boards can be connected together.

  In the above-described embodiment, the connection method of the printed wiring board has been described by taking an example in which only one second printed wiring board has a convex portion. However, the first printed wiring board has a convex portion. Further, both the pair of printed wiring boards may have a convex portion.

  Furthermore, in the connection method of the printed wiring board of the said embodiment, although the case where an anisotropic conductive adhesive film was temporarily bonded to two 1st printed wiring boards which do not have a convex part was demonstrated, anisotropic conductive The adhesive film may be temporarily bonded to a printed wiring board having a convex portion. Further, the anisotropic conductive adhesive film may be temporarily bonded to two sets of connection region groups of one second printed wiring board.

  In the printed wiring board connection structure of the present invention, the adhesive strength between the anisotropic conductive adhesive layer and the connection region can be obtained easily and reliably, and the production efficiency is high. Therefore, the connection structure of the printed wiring board can electrically connect the printed wiring board efficiently with high connection reliability. Moreover, since the electronic device of the present invention includes the connection structure for the printed wiring board, it has high connection reliability and high production efficiency.

DESCRIPTION OF SYMBOLS 1, 2 Printed wiring board 1a, 2a Base film 1b, 2b Conductive pattern 1c, 2c Connection terminal 1d, 2d Coverlay 3 Anisotropic conductive adhesive layer 4 Convex part 30 Anisotropic conductive adhesive film X Heating body Y Cushion material

Claims (9)

Electrical connection through an anisotropic conductive adhesive layer in the connection region where a pair of conductive patterns face each other in a pair of printed wiring boards having a base film having insulating properties and a conductive pattern laminated on one surface side thereof Printed wiring board connection structure,
The connection structure of the printed wiring board which has a convex part on the opposite side to the said connection area | region of at least one base film of a pair of said printed wiring board.   The printed wiring board connection structure according to claim 1, wherein the convex portion is formed of a metal material.   The printed wiring board connection structure according to claim 1, wherein a region where the convex portion is formed is smaller than the connection region.   The printed wiring board connection structure according to claim 1, wherein the base film of the printed wiring board having the convex portion is recessed in the facing direction in the connection region.   The average thickness of the convex portions is the total average thickness of the pair of conductive patterns facing each other in the connection region from the total average thickness of one or more films disposed between the pair of base films in the pair of printed wiring boards. The printed wiring board connection structure according to claim 1, wherein the printed wiring board connection structure is larger than a value obtained by subtracting the thickness.   The printed wiring board connection structure according to any one of claims 1 to 5, wherein the connection area is an arrangement area of connection terminals in a pair of printed wiring boards.   The printed wiring board connection structure according to any one of claims 1 to 6, wherein one of the pair of printed wiring boards is a single printed wiring board and the other is a plurality of printed wiring boards. .   An electronic apparatus comprising the printed wiring board connection structure according to any one of claims 1 to 7. A pair of printed wiring boards having an insulating base film and a conductive pattern laminated on one surface side thereof are electrically connected via an anisotropic conductive adhesive layer in a connection region where the pair of conductive patterns face each other. A printed wiring board connection method,
Overlaying the connection region of the pair of printed wiring boards via an anisotropic conductive adhesive film,
A step of thermocompression bonding the pair of printed wiring boards and the anisotropic conductive adhesive film in the connection region,
A method for connecting a printed wiring board, wherein a convex portion is provided on a side opposite to the connection region of at least one base film of the pair of printed wiring boards, and the convex portion is pressed by a heating body.

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