JP2008124082A - Wiring board connection structure and connection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure and a connection method of a wiring board that reduces the manufacturing cost as well as the miniaturization of electronic devices. <P>SOLUTION: A bonded wiring board 50 is formed by connecting a rigid wiring board 1 including a first electrode 4 formed on a first rigid base material 6 and a flexible wiring board 3 including a second electrode 5 formed on a second flexible base material 7. On the first base material 6, a recess part 11 for storing the second electrode 5 is formed and the first electrode 4 is formed on the front surface 12 of the recess part 11. The first the second electrodes 4, 5 are electrically connected by storing the second electrode 5 in the recess part 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a connection structure and a connection method for a wiring board used as a component of an electronic device.

  In recent years, in the electronic equipment field, with the increase in the density of electronic equipment, for example, flexible wiring boards are widely used for applications such as wiring to movable parts of electronic equipment. In addition, along with downsizing and higher functionality of electronic devices, for example, flexible wiring boards and rigid wiring boards, or wiring board assemblies having various shapes formed by connecting a plurality of flexible wiring boards Is used.

  Here, as a connection structure of a plurality of wiring boards, for example, a connection structure using a connector is used. More specifically, a flexible wiring board is disclosed in which a connector connection portion is formed at an end portion, and a connection terminal is formed on a conductor circuit layer whose surface is exposed in the connector connection portion. And it is the structure which connects a some flexible wiring board by inserting the said connection terminal in the connector insertion port formed in the connector (for example, refer patent document 1).

A structure in which a plurality of flexible wiring boards are connected using an anisotropic conductive adhesive is also known. More specifically, the first electrode provided on the first substrate of the first flexible wiring board and the second by performing heat and pressure treatment via an anisotropic conductive adhesive, The structure which connects the 1st, 2nd flexible wiring board by electrically connecting the 2nd electrode provided on the 2nd base material of this flexible wiring board is disclosed (for example, patent) Reference 2).
JP 2003-101167 A JP 2002-314216 A

  However, in the connection using the connector described in Patent Document 1, it is necessary to provide a connector for connecting the flexible wiring board, so that a space depending on the thickness of the connector is required. As a result, there is a problem that the entire thickness of the wiring board assembly is increased, and the electronic devices cannot be reduced in size. Moreover, since the connector is used, there is a problem that the manufacturing cost of the wiring board assembly increases.

  Also, in the connection structure described in Patent Document 2, since it is necessary to use a thick anisotropic conductive adhesive, the thickness of the anisotropic conductive adhesive is the same as in the case of using the connector described above. Space is required. As a result, there is a problem that the entire thickness of the wiring board assembly is increased, and the electronic devices cannot be reduced in size. Moreover, since the usage-amount of anisotropic conductive adhesive increases, there existed a problem that the manufacturing cost of a wiring board assembly became high.

  Accordingly, the present invention has been made in view of the above-described problems, and provides a wiring board connection structure and a connection method that can cope with downsizing of electronic devices and can reduce the manufacturing cost of a wiring board assembly. The purpose is to provide.

  In order to achieve the above object, the invention according to claim 1 is the first electrode formed on the first substrate of the first wiring board and the second substrate of the second wiring board. A wiring board connection structure for electrically connecting the second electrode formed above, wherein the first substrate is provided with a recess for accommodating the second electrode, and the recess A first electrode is formed on the surface, and the first and second electrodes are electrically connected by housing the second electrode in the recess.

  According to this configuration, when manufacturing the wiring board assembly by connecting the first wiring board and the second wiring board, a connector is unnecessary and a thick anisotropic conductive adhesive is used. There is no need to do it. Therefore, it is possible to reduce the overall thickness of the wiring board assembly including the first wiring board and the second wiring board. As a result, it is possible to obtain a wiring board assembly that can cope with downsizing of electronic devices. Moreover, it becomes possible to reduce the manufacturing cost of the wiring board assembly.

  Invention of Claim 2 is the connection structure of the wiring board of Claim 1, Comprising: The 1st, 2nd electrode is electrically connected via the conductive adhesive containing electroconductive particle. It is connected.

  According to this configuration, the first and second electrodes can be connected with a low conductive resistance, so that the conductivity between the first and second electrodes can be improved. In addition, even when the first and second electrodes are electrically connected via a conductive adhesive, the thickness of the conductive adhesive can be reduced. Compared to the structure, the amount of conductive adhesive used can be reduced. As a result, it becomes possible to reduce the manufacturing cost of the wiring board assembly. In addition, after connecting the electrodes via an adhesive, if the connected electrodes are misaligned, they are peeled off without causing damage or damage between the electrodes once connected, and the adhesive is removed from the solvent. After removal with (toluene, acetone, alcohol, etc.), the electrodes are connected again using an adhesive (hereinafter referred to as “repair”), but the amount of conductive adhesive used is reduced. Therefore, when performing repair, it becomes easy to completely remove the adhesive with a solvent, and the repairability of the adhesive can be improved.

  The invention according to claim 3 is the wiring board connection structure according to claim 2, wherein the conductive particles are a metal having a shape in which a large number of fine metal particles are connected in a straight chain or a needle shape. It is characterized by being a powder.

  According to this configuration, in the surface direction of the adhesive, insulation between adjacent electrodes is maintained to prevent a short circuit, and in the thickness direction, a large number of first electrodes and second electrodes are once connected. In addition, each can be connected independently to obtain a low resistance. Further, even when an expensive anisotropic conductive adhesive is used as the conductive adhesive, the amount of the anisotropic conductive adhesive used can be reduced. As a result, it is possible to reduce the manufacturing cost of the wiring board assembly as compared with the conventional connection method using the anisotropic conductive adhesive having a thickness.

  Invention of Claim 4 is the connection structure of the wiring board in any one of Claim 1 thru | or 3, Comprising: At least one of a 1st electrode and a 2nd electrode is formed with an electrically conductive paste. It is characterized by being. According to this configuration, at least one of the first electrode and the second electrode can be formed at low cost, and as a result, the manufacturing cost of the wiring board assembly can be reduced.

  According to a fifth aspect of the present invention, the first electrode formed on the surface of the recess formed in the first base member of the first wiring board and the second electrode connected to the first wiring board. A step of aligning the first electrode and the second electrode so that the second electrode formed on the second base member of the wiring board is connected, and the second electrode in the recess The wiring board connection method includes at least a step of electrically connecting the first electrode and the second electrode by housing.

  According to this configuration, when manufacturing the wiring board assembly by connecting the first wiring board and the second wiring board, a connector is unnecessary and a thick anisotropic conductive adhesive is used. There is no need to do it. Therefore, it is possible to reduce the overall thickness of the wiring board assembly including the first wiring board and the second wiring board. As a result, it is possible to obtain a wiring board assembly that can cope with downsizing of electronic devices. Moreover, it becomes possible to reduce the manufacturing cost of the wiring board assembly.

  According to the sixth aspect of the present invention, the first electrode formed on the surface of the recess formed in the first substrate of the first wiring board is electrically conductive mainly composed of a thermosetting resin. The step of placing the adhesive, the first electrode, and the second electrode formed on the second substrate of the second wiring board connected to the first wiring board are connected. And a step of aligning the first electrode and the second electrode with a conductive adhesive interposed between the first and second wiring boards, and storing the second electrode in the recess. By placing the second wiring board on the conductive adhesive and interposing the conductive adhesive between the first and second electrodes and performing heat and pressure treatment, thermosetting A method of connecting a wiring board, comprising: curing a resin and electrically connecting the first electrode and the second electrode;

  According to this configuration, when manufacturing the wiring board assembly by connecting the first wiring board and the second wiring board, a connector is unnecessary and a thick anisotropic conductive adhesive is used. There is no need to do it. Therefore, it is possible to reduce the overall thickness of the wiring board assembly including the first wiring board and the second wiring board. As a result, it is possible to obtain a wiring board assembly that can cope with downsizing of electronic devices. Moreover, it becomes possible to reduce the manufacturing cost of the wiring board assembly. In addition, since the first and second electrodes can be connected with a low conductive resistance, the conductivity between the first and second electrodes can be improved. In addition, even when the first and second electrodes are electrically connected via a conductive adhesive, the thickness of the conductive adhesive can be reduced. Compared to the structure, the amount of conductive adhesive used can be reduced. As a result, it becomes possible to reduce the manufacturing cost of the wiring board assembly. In addition, since it becomes possible to reduce the amount of conductive adhesive used, it is easy to completely remove the adhesive with a solvent when repairing, and the repairability of the adhesive can be improved. it can.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to obtain the wiring board assembly which can respond to size reduction of electronic devices. Moreover, it becomes possible to reduce the manufacturing cost of the wiring board assembly.

  Hereinafter, a preferred embodiment of the present invention will be described. FIG. 1 is a cross-sectional view for explaining a wiring board connection structure according to the present invention. In addition, in this embodiment, it has a rigid wiring board which has the 1st electrode formed on the rigid base material, and the 2nd electrode formed on the flexible base material as a to-be-joined member. A wiring board assembly using a flexible wiring board will be described as an example.

  As shown in FIG. 1, in the wiring board connection structure according to the present embodiment, an adhesive 2 is applied between a rigid wiring board 1 that is a first wiring board and a flexible wiring board 3 that is a second wiring board. And electrically connecting between the first electrode 4 formed on the rigid wiring board 1 and the second electrode 5 formed on the flexible wiring board 3 by performing heat and pressure treatment. It has become.

  As shown in FIG. 1, the rigid wiring board 1 includes a plurality of first electrodes 4 (in the present embodiment, two pieces) on one side of a rigid first substrate 6 formed of a glass substrate or the like. ) Is provided. In addition, as shown in FIG. 1, the flexible wiring board 3 includes a plurality of second electrodes 5 constituting a conductor circuit layer on one side of a flexible second substrate 7 formed of a flexible resin film. This is a so-called single-sided flexible wiring board provided (two in this embodiment). In addition, it is good also as a structure which provides the 2nd electrode 5 on the 2nd base material 7 through an adhesive bond layer (not shown).

  As a resin film which comprises the 2nd base material 7, what consists of a resin material excellent in the softness | flexibility is used. As such a resin film, for example, any resin film that is versatile for flexible wiring boards, such as a polyester film, can be used. In addition, it is particularly preferable that the resin film has high heat resistance in addition to flexibility, and examples of the resin film include polyamide resin films, polyimide resin films such as polyimide and polyamideimide, and polyethylene. Naphthalate is preferably used.

  Moreover, as the 2nd electrode 5 of this invention, metal foil, such as copper foil, is laminated | stacked on the surface of the 2nd base material 7, for example, the said metal foil is exposed, an etching, and a plating process by a conventional method. A copper electrode with a metal gold plating formed by doing so is used. Moreover, as the 1st electrode 4, the copper electrode by which the above-mentioned metal gold plating was given, and the metal ITO electrode formed on the 1st base material 6 are used, for example.

  In the present embodiment, the first and second electrodes 4 and 5 are formed on the surfaces of the first and second substrates 6 and 7 using the metal foil such as the copper foil described above. However, the first and second electrodes 4 and 5 may be formed by printing a conductive paste. By using such a method, exposure and etching required when using the metal foil are not required, and the manufacturing cost of the rigid wiring board 1 and the flexible wiring board 3 is reduced. Examples of the method for printing the conductive paste include a screen printing method and an intaglio printing method. Further, only one of the first and second electrodes 4 and 5 may be formed of a conductive paste.

  As the conductive paste, for example, a thermosetting conductive paste containing conductive powder, a binder resin, a curing agent, and a solvent as main components can be used. Here, for example, nickel, copper, silver, gold, or graphite can be used as the conductive powder. Moreover, a polyester resin, an epoxy resin, and a polyimide resin can be used for binder resin, for example. As the curing agent, for example, an isocyanate compound can be used when a polyester resin is used as a binder resin, and an amine compound or an imidazole compound can be used when an epoxy resin is used. Furthermore, as the solvent, for example, cellosolve, butyl acetate, cellosolve acetate, or butyl carbitol acetate can be used. Then, by applying the conductive paste to the surfaces of the first and second base materials 6 and 7 by the above-described screen printing method or the like, and applying the heat treatment to cure the binder resin, Two electrodes 4 and 5 are formed.

  In addition, as the adhesive 2 used in the present invention, an epoxy resin, which is an insulating thermosetting resin, which has been conventionally used for connecting the rigid wiring board 1 and the flexible wiring board 3, is mainly used. A conductive adhesive in which conductive particles are dispersed in a resin can be used. For example, an epoxy resin in which powder of conductive particles such as nickel, copper, silver, gold, or graphite is dispersed can be used. By using an epoxy resin as the thermosetting resin, it is possible to improve the film formability, heat resistance, and adhesive strength of the adhesive 2.

  The epoxy resin to be used is not particularly limited. For example, bisphenol A type, F type, S type, AD type, or a copolymer type epoxy resin of bisphenol A type and bisphenol F type, or naphthalene type epoxy is used. Resin, novolac type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin and the like can be used. A phenoxy resin that is a high molecular weight epoxy resin can also be used.

  The molecular weight of the epoxy resin can be selected as appropriate in consideration of the performance required for the adhesive 2. When a high molecular weight epoxy resin (that is, the above-mentioned phenoxy resin) is used, the film forming property is high, the dissolution viscosity of the resin at the connection temperature can be increased, and the connection can be made without disturbing the orientation of the conductive particles described later. There is. On the other hand, when a low molecular weight epoxy resin is used, the effect of increasing the crosslink density and improving the heat resistance is obtained. Moreover, the effect of reacting with the above-mentioned hardening | curing agent rapidly at the time of a heating, and improving adhesive performance is acquired. Therefore, it is preferable to use a combination of a high molecular weight epoxy resin having a molecular weight of 15000 or more and a low molecular weight epoxy resin having a molecular weight of 2000 or less in order to balance performance. In addition, the compounding quantity of a high molecular weight epoxy resin and a low molecular weight epoxy resin can be selected suitably. In addition, the “average molecular weight” here refers to a polystyrene-reduced weight average molecular weight obtained from gel permeation chromatography (GPC) developed with THF.

  Moreover, as the adhesive 2 used in the present invention, an adhesive containing a latent curing agent can be used. This latent curing agent is a curing agent that is excellent in storage stability at a low temperature and hardly undergoes a curing reaction at room temperature, but rapidly undergoes a curing reaction by heat or light. As this latent curing agent, imidazole series, hydrazide series, boron trifluoride-amine complex, amine imide, polyamine series, tertiary amine, alkyl urea series and other amine series, dicyandiamide series, acid anhydride series, phenol series These modified products are exemplified, and these can be used alone or as a mixture of two or more.

  Among these latent curing agents, an imidazole-based latent curing agent is preferably used from the viewpoint that it is excellent in storage stability at a low temperature and fast curability. As the imidazole-based latent curing agent, a known imidazole-based latent curing agent can be used. More specifically, an adduct of an imidazole compound with an epoxy resin is exemplified. Examples of the imidazole compound include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-dodecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 4-methylimidazole.

  In particular, these latent curing agents coated with a polymer material such as polyurethane and polyester, a metal thin film such as nickel and copper, and an inorganic material such as calcium silicate, This is preferable because it is possible to achieve both contradictory properties of storage stability and fast curability. Therefore, a microcapsule type imidazole-based latent curing agent is particularly preferable.

  As the adhesive 2, an anisotropic conductive adhesive containing conductive particles can also be used. More specifically, as the anisotropic conductive adhesive, for example, the above-described epoxy resin is the main component, and in the resin, fine metal particles (for example, spherical metal fine particles or metal) shown in FIG. Conductive particles 10 made of metal powder having a large number of metal fine particles (plated spherical resin particles) having a linear shape, a needle shape, or a so-called high aspect ratio shape are dispersed. Can be used. The aspect ratio referred to here is the ratio of the short diameter (the length of the cross section of the conductive particles 10) R and the long diameter (the length of the conductive particles 10) L of the conductive particles 10 shown in FIG. Say.

  By using such conductive particles 10, as an anisotropic conductive adhesive, in the surface direction of the adhesive 2 (the direction perpendicular to the thickness direction X and the direction of the arrow Y in FIG. 1), In the thickness direction X, while maintaining insulation between adjacent electrodes and preventing a short circuit, a large number of first electrodes 4 -second electrodes 5 are connected at a time and independently to each other. It becomes possible to obtain resistance.

  The aspect ratio of the conductive particles 10 is preferably 5 or more. By using such conductive particles 10, when an anisotropic conductive adhesive is used as the adhesive 2, the contact probability between the conductive particles 10 is increased. Therefore, the first electrode 4 and the second electrode 5 can be electrically connected without increasing the blending amount of the conductive particles 10.

  In this anisotropic conductive adhesive, a magnetic field applied in the direction of the long diameter L of the conductive particles 10 in the thickness direction X of the anisotropic conductive adhesive at the time of forming the film-like anisotropic conductive adhesive. It is preferable to use it in the thickness direction X by passing through the inside. By adopting such an orientation, the above-described insulation between adjacent electrodes is maintained to prevent a short circuit, and a large number of first electrodes 4 to the second electrodes 5 are formed at once, and each is independent. Thus, the effect of being able to conduct conductive connection is further improved.

  In addition, the metal powder used in the present invention preferably contains a ferromagnetic material in part, such as a single metal having ferromagnetism, two or more kinds of alloys having ferromagnetism, a metal having ferromagnetism and others. It is preferably any one of an alloy with the above metal and a composite containing a metal having ferromagnetism. This is because by using a metal having ferromagnetism, the conductive particles 10 can be oriented using a magnetic field due to the magnetism of the metal itself. For example, nickel, iron, cobalt, and two or more kinds of alloys containing these can be used.

  The aspect ratio of the conductive particles 10 is directly measured by a method such as observation with a CCD microscope. In the case of the conductive particles 10 whose cross section is not a circle, the aspect ratio is obtained by setting the maximum length of the cross section as the short diameter. Further, the conductive particles 10 do not necessarily have a straight shape, and can be used without any problems even if they are slightly bent or branched. In this case, the aspect ratio is obtained by setting the maximum length of the conductive particles 10 as the major axis.

  Here, in the present embodiment, as shown in FIGS. 1 and 3, a recess 11 for housing the second electrode 5 is formed in the first base 6, and the surface of the recess 11 is formed. This is characterized in that the first electrode 4 is formed on 12. And in the connection structure of the wiring board of this embodiment, it has the structure by which the 1st, 2nd electrodes 4 and 5 are electrically connected by accommodating the 2nd electrode 5 in the recessed part 11. FIG. .

  Such a configuration eliminates the need for a connector necessary for the above-described conventional connection method and eliminates the need to use a thick anisotropic conductive adhesive, so that the rigid wiring board 1 and the flexible wiring board 3 are connected. It becomes possible to reduce the thickness of the part. Accordingly, it is possible to reduce the thickness of the entire wiring board assembly 50 composed of the rigid wiring board 1 and the flexible wiring board 3, and as a result, the wiring board assembly 50 that can cope with downsizing of electronic devices. Can be obtained. In addition, since a connector is not necessary and it is not necessary to use a thick anisotropic conductive adhesive, the manufacturing cost of the wiring board assembly 50 can be reduced.

  Moreover, in order to improve the electroconductivity between the 1st, 2nd electrodes 4 and 5, even when it is a case where the above-mentioned electroconductive adhesive is used as the adhesive agent 2, the thickness of the said electroconductive adhesive agent is set. Since the thickness can be reduced, the amount of conductive adhesive used can be reduced, and the manufacturing cost of the wiring board assembly 50 can be reduced.

  In particular, when an expensive anisotropic conductive adhesive is used as the conductive adhesive, the amount of the anisotropic conductive adhesive used can be reduced. Compared to a connection method using a conductive adhesive, the manufacturing cost of the wiring board assembly 50 can be reduced.

  Moreover, in the connection method using the anisotropic conductive adhesive with the above-mentioned conventional thickness, since the amount of the anisotropic conductive adhesive is large, the adhesive is completely removed with a solvent when repairing. There is a problem that the repairability of the adhesive is lowered.

  On the other hand, in this embodiment, as described above, the thickness of the conductive adhesive can be reduced and the amount of the conductive adhesive used can be reduced. It is easy to remove the adhesive, and the repairability of the adhesive can be improved.

  When the rigid wiring board 1 is manufactured, for example, laser processing or sand blasting is performed on one side of the rigid first base 6 formed of a glass base or the like shown in FIG. As a result, as shown in FIG. 3B, a recess 11 for accommodating the second electrode 5 is formed. Next, for example, a conductive paste is printed on the surface 12 of the recess 11 by the above-described screen printing method, so that the first electrode is formed on the surface 12 of the recess 11 as shown in FIG. 4 to form a rigid wiring board 1 having a plurality of first electrodes 4.

  Moreover, the flexible wiring board 3 can be manufactured in the same manner as in the past. That is, for example, when using the above-described conductive paste, by printing the conductive paste on one side of the second substrate 7 formed of a flexible resin film by the above-described screen printing method, A flexible wiring board 3 having a plurality of second electrodes 5 is produced.

  In addition, as a method of connecting the rigid wiring board 1 and the flexible wiring board 3 using the anisotropic conductive adhesive that is the adhesive 2, heating and pressurizing treatment is performed via the anisotropic conductive adhesive. By performing, a method of curing and connecting the thermosetting resin in the anisotropic conductive adhesive can be adopted.

  More specifically, as shown in FIG. 4A, the first formed on the surface 13 of the first substrate 6 and the surface 12 of the recess 11 of the rigid wiring board 1 manufactured by the above-described method. On the surface of the electrode 4, an anisotropic conductive adhesive, which is the adhesive 2 containing the above-described conductive particles 10, which is mainly composed of an epoxy resin that is an insulating thermosetting resin, is placed. Next, while the anisotropic conductive adhesive is heated to a predetermined temperature, the anisotropic conductive adhesive is pressurized with a predetermined pressure in the direction of the rigid wiring board 1 to temporarily bond the anisotropic conductive adhesive onto the rigid wiring board 1. The anisotropic conductive adhesive can be used in the form of a paste, but an anisotropic conductive adhesive having a film shape can also be suitably used.

  Next, as shown in FIG. 4B, the rigid wiring board 1 and the flexible wiring board are connected so that the flexible wiring board 3 faces downward and the first electrode 4 and the second electrode 5 are connected. The first electrode 4 formed on the surface 12 of the concave portion 11 of the rigid wiring board 1 and the second electrode formed on the surface of the flexible wiring board 3 with an anisotropic conductive adhesive interposed between them. Alignment with the electrode 5 is performed.

  Next, as shown in FIG. 4C, the flexible wiring board 3 is placed on the anisotropic conductive adhesive by accommodating the second electrode 5 in the recess 11, and the first and second electrodes are placed on the anisotropic conductive adhesive. An anisotropic conductive adhesive is interposed between the electrodes 4 and 5.

  Next, in the state where the anisotropic conductive adhesive is heated to a predetermined temperature, the anisotropic conductive adhesive is shown in the direction of the rigid wiring board 1 through the flexible wiring board 3 (that is, as shown in FIG. 4C). , In the direction of arrow A) at a predetermined pressure, the anisotropic conductive adhesive is heated and melted. As described above, since the anisotropic conductive adhesive is mainly composed of an epoxy resin which is a thermosetting resin, the anisotropic conductive adhesive softens once when heated at the above temperature. However, it will be cured by continuing the heating. Then, after the preset curing time of the anisotropic conductive adhesive has elapsed, the anisotropic conductive adhesive is released from the state of maintaining the curing temperature of the anisotropic conductive adhesive and the pressurized state, and starts cooling. The first electrode 4 and the second electrode 5 are connected via an adhesive, and the flexible wiring board 3 is mounted on the rigid wiring board 1. With the above-described wiring board connection method, the wiring board assembly 50 including the rigid wiring board 1 and the flexible wiring board 3 shown in FIG. 1 can be manufactured.

According to the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment, the first substrate 6 is formed with the recess 11 in which the second electrode 5 is accommodated, and the first electrode 4 is formed on the surface 12 of the recess 11. It is said. The first electrode 4 and the second electrode 5 are electrically connected by housing the second electrode 5 in the recess 11. Accordingly, when the rigid wiring board 1 and the flexible wiring board 3 are connected, a connector is not necessary and it is not necessary to use a thick anisotropic conductive adhesive. It becomes possible to reduce the thickness of the whole wiring board assembly 50 made of the above. As a result, it is possible to obtain the wiring board assembly 50 that can cope with the downsizing of electronic devices. Further, the manufacturing cost of the wiring board assembly 50 can be reduced.

  (2) In the present embodiment, a conductive adhesive containing conductive particles is used as the adhesive 2, and the first and second electrodes 4 and 5 are electrically connected via the conductive adhesive. It is configured to connect to. Accordingly, since the first and second electrodes 4 and 5 can be connected with a low conductive resistance, the conductivity between the first and second electrodes 4 and 5 can be improved. Further, even when the first and second electrodes 4 and 5 are electrically connected via a conductive adhesive, the thickness of the conductive adhesive can be reduced. It becomes possible to reduce the usage-amount of an agent. As a result, it becomes possible to reduce the manufacturing cost of the wiring board assembly 50, and it becomes easy to completely remove the adhesive 2 with a solvent when repairing, thereby improving the repairability of the adhesive 2. Can be improved.

  (3) In the present embodiment, as the adhesive 2, a conductive adhesive containing conductive particles 10 that are metal powder having a shape in which a large number of fine metal particles are connected in a straight chain or a needle shape. Thus, the first and second electrodes 4 and 5 are electrically connected. Therefore, in the surface direction Y of the adhesive 2, while maintaining insulation between adjacent electrodes to prevent a short circuit, in the thickness direction X, a large number of first electrodes 4-between the second electrodes 5, It is possible to obtain a low resistance by connecting each at a time and independently. Further, even when an expensive anisotropic conductive adhesive is used as the conductive adhesive, it is possible to reduce the amount of the anisotropic conductive adhesive used. As a result, it is possible to reduce the manufacturing cost of the wiring board assembly 50 as compared with the conventional connection method using the anisotropic conductive adhesive having a thickness.

  (4) In the present embodiment, at least one of the first electrode 4 and the second electrode 5 is formed of a conductive paste. Therefore, at least one of the first electrode 4 and the second electrode 5 can be formed at low cost, and as a result, the manufacturing cost of the wiring board assembly 50 can be reduced.

In addition, you may change the said embodiment as follows.
In the above embodiment, the wiring board assembly 50 using the rigid wiring board 1 and the flexible wiring board 3 has been described as an example. However, instead of the rigid wiring board 1 used in the above embodiment, other wiring board 1 It is good also as a structure which uses a flexible wiring board and uses a some flexible wiring board as a to-be-joined member. Similarly, another rigid wiring board may be used instead of the flexible wiring board 3 used in the above-described embodiment, and a plurality of rigid wiring boards may be used as members to be joined.

  -In the said embodiment, by performing a heating-pressing process between the rigid wiring board 1 and the flexible wiring board 3 via the adhesive agent 2, between the 1st electrode 4 and the 2nd electrode 5, Although it is configured to be electrically connected, the first electrode 4 and the second electrode 5 may be directly contacted to be electrically connected without using the adhesive 2.

  In the above embodiment, the first and second electrodes 4 and 5 are formed of a metal foil such as a copper foil or a conductive paste. However, the first and second electrodes are formed by an inkjet method. It is good also as a structure formed by. Here, the ink jet method uses a material obtained by dissolving or dispersing the materials of the first and second electrodes in a liquid, which is a fluid, as an ejected material, and a predetermined amount of the ejected material is placed at a predetermined position. The first and second electrodes are formed by injecting into

  Examples of utilization of the present invention include connection structures and connection methods for wiring boards used as components of electronic equipment.

It is sectional drawing which shows the connection structure of the wiring board which concerns on embodiment of this invention. It is the schematic for demonstrating the electroconductive fine particles which the anisotropic conductive adhesive used in the connection structure of the wiring board which concerns on embodiment of this invention contains. (A)-(c) is sectional drawing for demonstrating the manufacturing process of the rigid wiring board which has a recessed part. (A)-(c) is sectional drawing for demonstrating the manufacturing method of the wiring board assembly which has the connection structure of the wiring board which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rigid wiring board, 2 ... Adhesive (conductive adhesive), 3 ... Flexible wiring board, 4 ... 1st electrode, 5 ... 2nd electrode, 6 ... 1st base material, 7 ... 2nd Base material, 10 ... conductive particles, 11 ... concave portion, 12 ... surface of concave portion, 13 ... surface of first base material, 50 ... wiring board assembly

Claims (6)

Wiring for electrically connecting the first electrode formed on the first substrate of the first wiring board and the second electrode formed on the second substrate of the second wiring board Board connection structure,
The first base is formed with a recess for storing the second electrode, the first electrode is formed on the surface of the recess, and the second electrode is stored in the recess. Thus, the wiring board connection structure, wherein the first and second electrodes are electrically connected.   The wiring board connection structure according to claim 1, wherein the first and second electrodes are electrically connected via a conductive adhesive containing conductive particles.   3. The wiring board connection structure according to claim 2, wherein the conductive particles are metal powder having a shape in which a large number of fine metal particles are connected in a straight chain or a needle shape.   4. The wiring board connection structure according to claim 1, wherein at least one of the first electrode and the second electrode is formed of a conductive paste. 5. A first electrode formed on a surface of a recess formed in a first substrate of the first wiring board, and a second electrode of the second wiring board connected to the first wiring board. A step of aligning the first electrode and the second electrode so that the second electrode formed on the substrate is connected;
A method of connecting a wiring board, comprising: at least a step of electrically connecting the first electrode and the second electrode by housing the second electrode in the recess. Placing a conductive adhesive mainly composed of a thermosetting resin on the first electrode formed on the surface of the recess formed in the first substrate of the first wiring board;
The first and second electrodes are connected so that the first electrode is connected to a second electrode formed on a second substrate of a second wiring board connected to the first wiring board. A step of aligning the first electrode and the second electrode with the conductive adhesive interposed between the two wiring boards;
By housing the second electrode in the recess, the second wiring board is placed on the conductive adhesive, and the conductive adhesive is placed between the first and second electrodes. An intervening step;
A wiring board comprising: at least a step of curing the thermosetting resin by performing a heat and pressure treatment and electrically connecting the first electrode and the second electrode. Connection method.

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