JP6111771B2 - Circuit member, connection structure, and manufacturing method of connection structure - Google Patents

Description

  The present invention relates to a circuit member, a connection structure, and a method for manufacturing the connection structure.

  Conventionally, as a method of electrically connecting circuit members, a connection method using an anisotropic conductive adhesive is known (see, for example, Patent Documents 1 and 2). In this method, the electrodes between the circuit members are electrically connected by crimping the circuit members through an anisotropic conductive adhesive containing conductive particles and an adhesive component, and at the same time, in the same circuit member Insulation between adjacent electrodes is ensured.

JP-A-60-191228 JP-A-1-251787

  In recent years, with the miniaturization and thinning of electronic devices, the density of circuits has been increasing, and the area and spacing of electrodes have become very narrow. Therefore, when connecting circuit members using an anisotropic conductive adhesive, in order to capture a predetermined number of conductive particles between the circuit members, increasing the amount of conductive particles in the anisotropic conductive adhesive, There may be a short circuit between adjacent electrodes. On the other hand, in order to prevent said short circuit, there exists a problem that connection reliability will be impaired when the quantity of the electrically-conductive particle in anisotropic conductive adhesive is decreased.

  The present invention has been made in order to solve the above-described problems. A circuit member, a connection structure, and a circuit structure that can ensure connection reliability even when the amount of conductive particles in the anisotropic conductive adhesive is reduced. An object of the present invention is to provide a method for manufacturing a connection structure.

  A circuit member according to the present invention includes a substrate and an electrode formed on at least one surface of the substrate, and is a circuit that is crimped to another substrate via an anisotropic conductive adhesive containing conductive particles and an adhesive component. It is a member, Comprising: The hole part into which an anisotropic conductive adhesive flows in in the case of crimping | compression-bonding is formed, and it is characterized by the above-mentioned.

  In this circuit member, a hole into which the anisotropic conductive adhesive flows when the circuit member is pressure-bonded to another circuit member is formed in the electrode. By this hole portion, the anisotropic conductive adhesive flows toward the electrode during pressure bonding, and the conductive particles can be concentrated in the vicinity of the electrode. Therefore, connection reliability can be ensured even when the amount of conductive particles in the anisotropic conductive adhesive is small.

  The hole portion allows the inflow of the adhesive component even when the conductive particles are dammed by the particle damming portion that dams the conductive particles when the anisotropic conductive adhesive flows. It is preferable to have an adhesive inflow portion. In this case, the conductive particles can be concentrated near the electrode by the particle blocking portion. Further, even after the conductive particles are densely packed, the adhesive component can be caused to flow into the hole portion by the adhesive inflow portion, so that the dense effect of the conductive particles can be continuously generated.

  The hole is preferably formed to a depth penetrating the electrode. In this case, since the volume in which the anisotropic conductive adhesive flows into the hole can be ensured, the flow of the anisotropic conductive adhesive toward the electrode can be generated more reliably.

  It is preferable that the hole is formed with a depth reaching the inside of the substrate. In this case, since the volume in which the anisotropic conductive adhesive flows into the hole can be ensured, the flow of the anisotropic conductive adhesive toward the electrode can be generated more reliably.

  The hole is preferably formed to a depth penetrating the substrate. In this case, since the volume in which the anisotropic conductive adhesive flows into the hole can be ensured, the flow of the anisotropic conductive adhesive toward the electrode can be generated more reliably.

  In addition, the connection structure according to the present invention pressure-bonds circuit members each including a substrate and an electrode formed on one surface of the substrate via an anisotropic conductive adhesive containing conductive particles and an adhesive component. In this connection structure, at least one of the electrodes of the circuit member is formed with a hole into which the anisotropic conductive adhesive has flowed during the crimping.

  In this connection structure, a hole into which the anisotropic conductive adhesive has flowed when the circuit members are pressure-bonded is formed in the electrode. By this hole portion, the anisotropic conductive adhesive flows toward the electrode during pressure bonding, and the conductive particles can be concentrated in the vicinity of the electrode. Therefore, connection reliability can be ensured even when the amount of conductive particles in the anisotropic conductive adhesive is small.

  Furthermore, in the method for manufacturing a connection structure according to the present invention, circuit members including a substrate and an electrode formed on one surface side of the substrate are connected to each other via an anisotropic conductive adhesive containing conductive particles and an adhesive component. A connection structure formed by pressure bonding, wherein a hole is formed in at least one electrode of a circuit member, and an anisotropic conductive adhesive is allowed to flow into the hole during the pressure bonding. .

  In the manufacturing method of this connection structure, the anisotropic conductive adhesive flows toward the electrodes by flowing the anisotropic conductive adhesive into the holes formed in the electrodes when the circuit members are crimped together. Conductive particles can be concentrated in the vicinity of the electrodes. Therefore, connection reliability can be ensured even when the amount of conductive particles in the anisotropic conductive adhesive is small.

  According to the present invention, connection reliability can be ensured even when the amount of conductive particles in the anisotropic conductive adhesive is reduced.

It is sectional drawing which shows one Embodiment of the connection structure which concerns on this invention. It is a top view which shows one Embodiment of the circuit member applied to the connection structure shown in FIG. It is the II sectional view taken on the line of FIG. It is a top view which shows the electrode with which a circuit member is provided. It is sectional drawing which shows one Embodiment of the manufacturing method of the connection structure which concerns on this invention. It is a conceptual diagram which shows the effect | action of a hole. It is sectional drawing which shows the structure of the hole formed in the electrode which concerns on a modification. It is a top view which shows the structure of the hole formed in the electrode which concerns on a modification. Fig.9 (a) is a top view which shows the circuit member which concerns on a modification, FIG.9 (b) is the II-II sectional view taken on the line of Fig.9 (a).

  Hereinafter, preferred embodiments of a circuit member, a connection structure, and a method for manufacturing the connection structure according to the present invention will be described in detail with reference to the drawings.

[Configuration of connection structure]
FIG. 1 is a cross-sectional view showing a connection structure according to an embodiment of the present invention. As shown in FIG. 1, the connection structure 1 is configured by joining a circuit member 2 and a circuit member 12 via an anisotropic conductive adhesive 5 including conductive particles 51 and an adhesive component 52. ing.

  The circuit member 2 includes a substrate 3 and an electrode 4 formed on one surface side of the substrate 3. As the circuit member 2, an IC chip, an FPC (flexible printed wiring board), or the like is used. When the circuit member 2 is an IC chip, a semiconductor silicon substrate or the like is used as the substrate 3 and a bump electrode made of Au or the like is used as the electrode 4. When the circuit member 2 is FPC, a polyimide substrate or the like is used as the substrate 3, and an electrode made of copper foil or the like is used as the electrode 4.

  The circuit member 12 includes a substrate 13 and an electrode 14 formed on one surface side of the substrate 13. A liquid crystal display or the like is used as the circuit member 12. When the circuit member 12 is a liquid crystal display, a glass substrate or the like is used as the substrate 13, and an ITO (indium tin oxide) electrode or the like is used as the electrode 14.

  In the connection structure 1, the electrode 4 and the electrode 14 are pressed against each other via the anisotropic conductive adhesive 5, and the electrode 4 and the electrode 14 mesh with the conductive particles 51, thereby connecting the circuit member 2. Electrical connection with the circuit member 12 is realized.

  The anisotropic conductive adhesive 5 includes conductive particles 51 and an adhesive component 52. The conductive particles 51 and the adhesive component 52 are appropriately blended depending on the application in such a ratio that the conductive particles are, for example, 0.01 to 50% by volume, preferably 0.1 to 30% by volume with respect to 100% by volume of the adhesive component. The Thereby, a sufficient number of conductive particles can be interposed between the electrode 4 and the electrode 14.

  As the conductive particles 51, metal particles such as Au, Ag, Ni, Cu, and solder, or particles obtained by coating nonconductive particles such as carbon, glass, ceramic, and plastic with noble metals such as Au, Ag, and Pt are used. . When metal particles are used as the conductive particles 51, it is preferable to use a particle whose surface is coated with a noble metal in order to suppress oxidation of the particle surface.

  Among the conductive particles, the conductive particles obtained by coating plastic particles with Au, Ag, and the like and the metal particles that are thermally melted are deformed when the circuit members are pressed together to increase the contact area between the conductive particles and the electrodes. This is preferable because the connection reliability can be further improved. Conductive particles obtained by coating plastic particles with Au, Ag, or the like are more preferable because they can ensure insulation reliability between adjacent electrodes in the same circuit member.

  In order to ensure connection reliability, the thickness of the coating layer in the case where metal particles or non-conductive particles are coated with a noble metal is, for example, preferably 10 nm or more, and more preferably 30 nm or more. Moreover, it is preferable to further coat the conductive particles with an insulating material. In this case, it becomes easy to ensure connection reliability and insulation reliability by setting the thickness of the coating layer to 20 to 500 nm, for example. Moreover, it is preferable that the magnitude | size of the electrically-conductive particle 51 is 500-50000 nm in diameter, for example.

  The diameter of the conductive particles is appropriately selected depending on the electrode area to be joined and the distance between adjacent electrodes. However, if the diameter is less than 500 nm, the conductive particles enter the unevenness of the circuit surface to be joined, and the connection reliability is likely to decrease. Become. Moreover, when a diameter exceeds 50000 nm, it will become easy to short-circuit between adjacent electrodes.

  From the viewpoint of connection reliability, the adhesive component 52 is a thermosetting containing an epoxy resin, a (meth) acrylic resin, a maleimide resin, a citraconic imide resin, a nadiimide resin, or a phenol resin, and a thermal polymerization initiator, a curing agent, and the like. It is preferably composed of a photocurable resin; a photocurable resin containing an epoxy resin, a (meth) acrylic resin, etc. and a photopolymerization initiator; or a resin using these in combination. The adhesive component 52 contains a thermoplastic resin such as acrylic rubber, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer from the viewpoint of film moldability and stress relaxation during adhesion. Is preferred.

  In addition, from the viewpoint of the adhesion of the anisotropic conductive adhesive 5 and the stress relaxation property during curing, the adhesive component 52 is a polyvinyl butyral resin, a polyvinyl formal resin, a polyester resin, a polyamide resin, a polyimide resin, a xylene resin, Polymer components such as phenoxy resin, polyurethane resin, urea resin, and acrylic rubber can be included. These polymer components preferably have a molecular weight of 10,000 to 10,000,000, and preferably have a functional group such as a carboxyl group, a hydroxyl group, and an epoxy group from the viewpoint of improving adhesiveness.

[Configuration of circuit members]
FIG. 2 is a plan view showing an embodiment of the circuit member 2. 3 is a cross-sectional view taken along the line II of FIG. 2, and FIG. 4 is a plan view showing the electrode 4 provided in the circuit member 2. As shown in FIG. As shown in FIG. 2, in this circuit member 2, a plurality of electrodes 4 are arranged at a constant interval on one surface side of the substrate 3. Each electrode 4 is formed with a hole 41 through which the anisotropic conductive adhesive 5 flows during crimping.

  As shown in FIG. 3, the hole 41 is formed with a depth that penetrates the electrode 4 and the substrate 3. As shown in FIG. 4, the hole 41 has a planar shape in which a circle with a radius L1 and a circle with a radius L2 partially overlap each other. L1 and L2 are smaller than the diameter L of the conductive particles 51, and the length L3 from one end to the other end of the hole 41 in the longitudinal direction is larger than the diameter L of the conductive particles 51. Note that L1 and L2 may be the same or different.

  In such a hole 41, when the circuit member 2 is pressure-bonded to the circuit member 12, the two sharp inward wall portions positioned substantially at the center of the hole 41 cause the conductive particles 51 to enter the hole 41. Acts as a particle blocking portion 41a. Even when the conductive particles 51 are blocked by the particle blocking portion 41a, the portion of the hole 41 that protrudes from the conductive particles 51 blocked by the particle blocking portion 41a acts as the adhesive inflow portion 41b. (Details will be described later).

  The number of the holes 41 is not particularly limited, but the total volume of the holes 41 formed in the circuit member 2 is preferably 50 to 150% with respect to the volume of the anisotropic conductive adhesive 5. If the total volume of the holes 41 is smaller than 50%, the holes 41 are immediately filled with the anisotropic conductive adhesive 5, and the anisotropic conductive adhesive 5 not flowing into the holes 41 is removed from the electrode 4. Since the particles flow away from each other, the conductive particles 51 can be easily dispersed without being concentrated in the electrode 4. If the total volume of the holes 41 is larger than 150%, the holes 41 are not sufficiently filled with the anisotropic conductive adhesive 5, and moisture enters from the holes 41 and the connection reliability is likely to be lowered.

[Method of manufacturing connection structure]
FIG. 5 is a cross-sectional view showing a method for manufacturing a connection structure according to an embodiment of the present invention. As shown in FIG. 5A, first, the circuit member 2 and the circuit member 12 are prepared. A hole 41 is formed in the electrode 4 in advance. As a method for forming the hole 41 in the electrode 4, known methods such as mechanical drilling, punching, chemical etching, sand blasting, electron beam machining, electric discharge machining, and laser drilling can be used.

  Next, as shown in FIG. 5B, the circuit member 2 and the circuit are connected via the anisotropic conductive adhesive 5 including the conductive particles 51 and the adhesive component 52 so that the electrode 4 and the electrode 14 face each other. The member 12 is arrange | positioned, and as shown in FIG.5 (c), it press-fits to the circuit member 2 and the circuit member 12 by applying a pressure to the direction of the arrow A and the arrow B, respectively. At the time of this crimping, as shown by an arrow C, the anisotropic conductive adhesive 5 flows into the hole 41 formed in the electrode 4. Therefore, the adhesive component 52 flows toward the electrode 4, and accordingly, as indicated by an arrow D, the conductive particles 51 are concentrated near the electrode 4. Then, the connection structure 1 shown in FIG. 1 is obtained by hardening the adhesive agent component 52 by heating or light irradiation.

[Function and effect of hole]
FIG. 6 is a conceptual diagram showing the operation of the hole. When the circuit member 2 and the circuit member 12 are pressure-bonded, the anisotropic conductive adhesive 5 tends to flow into the hole 41. At this time, the two sharp inward wall portions located substantially in the center of the hole portion 41 act as a particle blocking portion 41 a for blocking the conductive particles 51. Therefore, the conductive particles 51 are caught by the particle damming portion 41 a and dammed at the inlet of the hole 41.

  On the other hand, even when the conductive particles 51 are blocked by the particle blocking portion 41a, both end portions of the hole portion 41 are maintained open, and act as an adhesive inflow portion 41b that allows the adhesive component 52 to flow in. To do. Therefore, as shown by the arrow C, the adhesive component 52 can flow into the hole 41 from the adhesive inflow portion 41b.

  As described above, during the pressure bonding, the adhesive component 52 continuously flows into the hole 41 from the adhesive inflow portion 41b, while the conductive particles 51 flow toward the electrode 4 as indicated by the arrow D, By being dammed by the damming portion 41a, it is concentrated near the electrode 4. Therefore, even when the amount of the conductive particles 51 in the anisotropic conductive adhesive 5 is small, the electrode 4 and the electrode 14 can reliably mesh the conductive particles 51, and the connection reliability between the circuit member 2 and the circuit member 12 can be ensured. Sex is secured.

  Even when the plurality of conductive particles 51 are densely arranged in the vicinity of the electrode 4 so as to cover the hole 41, the conductive particles 51 are substantially spherical, so that the conductive particles 51 may completely block the hole 41. In addition, the adhesive component 52 is not prevented from flowing into the hole 41 from the adhesive inflow portion 41b.

[Modification]
In the embodiment described above, the hole 41 is formed with a depth that penetrates the electrode 4 and the substrate 3, but the depth of the hole 41 is the amount of the anisotropic conductive adhesive 5 used during pressure bonding, It can be appropriately modified according to the blending ratio of the conductive particles 51 and the adhesive component 52 in the anisotropic conductive adhesive 5. For example, as shown in FIG. 7A, the hole 41 may be formed at a depth that does not penetrate the electrode 4, and the hole 41 penetrates only the electrode 4 as shown in FIG. 7B. The hole 41 may be formed with a depth that penetrates the electrode 4 and reaches the inside of the substrate 3 as shown in FIG. When the hole 41 is deep, the inflow amount of the anisotropic conductive adhesive 5 can be sufficiently secured, and when it is shallow, the strength of the substrate 3 or the electrode 4 can be further secured.

  In the above-described embodiment, the hole 4 having a planar shape as shown in FIG. 4 is formed in the electrode 4. However, the electrode 4 has a planar shape as shown in FIGS. A hole 41 may be formed.

  In FIG. 8A, the hole 41 has a rectangular shape. When the length L4 of the short side of the hole 41 is smaller than the diameter L of the conductive particle 51, the wall of the long side of the hole 41 acts as the particle blocking part 41a. Further, since the length L5 of the long side of the hole 41 is larger than the diameter L of the conductive particle 51, the portion of the hole 41 that protrudes from the conductive particle 51 blocked by the particle blocking portion 41a is adhesive. It acts as an inflow portion 41b.

  In FIG. 8B, the hole 41 has a planar shape in which three circles each having a radius of L6, L7, and L8 partially overlap each other so that the centers of the three circles form a vertex of a triangle. have. Note that L6, L7, and L8 may be the same as or different from each other.

  In the hole 41, L6, L7, and L8 are smaller than the diameter L of the conductive particles 51, so that a sharp wall located at the approximate center of the hole 41 acts as the particle blocking part 41a. Further, since the length L9 from one end to the other end of the hole 41 is larger than the diameter L of the conductive particle 51, a portion of the hole 41 protruding from the conductive particle 51 blocked by the particle blocking portion 41a is formed. It acts as an adhesive inflow portion 41b.

  In FIG. 8C, the hole 41 has a plane in which four circles each having a radius of L10, L11, L12, and L13 partially overlap or touch at least two of the other circles. It has a shape. L10, L11, L12, and L13 may be the same as or different from each other.

  In the hole 41, L10, L11, L12, and L13 are smaller than the diameter L of the conductive particles 51, so that the sharp wall located at the approximate center of the hole 41 acts as the particle blocking part 41a. . Further, when the length L14 from one end to the other end of the hole 41 is larger than the diameter L of the conductive particle 51, the portion of the hole 41 that protrudes from the conductive particle 51 blocked by the particle blocking portion 41a. Acts as the adhesive inflow portion 41b.

  In FIG. 8 (d), the hole 41 has a mesh shape composed of a plurality of rectangles arranged in parallel to each other at regular intervals and a plurality of rectangles arranged in parallel to each other at regular intervals so as to be orthogonal to the rectangles. It has the planar shape. Since the length L15 of the rectangular short side is smaller than the diameter L of the conductive particles 51, the electrode portion located at the approximate center of the hole 41 acts as the particle blocking portion 41a. Further, since the long side length L16 of the rectangle is larger than the diameter L of the conductive particles 51, the portion of the hole 41 that protrudes from the conductive particles 51 blocked by the particle blocking portions 41a flows into the adhesive. Acts as part 41b.

  In FIG. 8E, the hole 41 has a planar shape in which a plurality of circles are two-dimensionally arranged at regular intervals. Since the diameter L17 of each circular hole is smaller than the diameter L of the conductive particles 51, the electrode portion located between the holes acts as the particle blocking portion 41a. Further, when the length L18 from one end to the other end of the hole 41 is larger than the diameter L of the conductive particle 51, the portion of the hole 41 that protrudes from the conductive particle 51 blocked by the particle blocking portion 41a. Acts as the adhesive inflow portion 41b.

  In the above-described embodiment, the electrode 4 has a substantially square shape as shown in FIGS. 4 and 8 and the like. However, as shown in FIG. It may have a rectangular shape that is significantly longer than. In this case, the hole 41 has a rectangular shape with a length penetrating in the long side direction of the electrode 4.

  9B, which is a II-II diagram of FIG. 9A, the hole 41 is formed with a depth that does not penetrate the electrode 4. In the hole portion 41, the length L19 of the short side of the hole portion 41 is smaller than the diameter L of the conductive particles 51, so that a part of the wall portion on the long side of the hole portion 41 acts as the particle blocking portion 41a. To do. In addition, since the length L20 of the long side of the hole is larger than the diameter L of the conductive particle 51, the portion of the hole 41 that protrudes from the conductive particle 51 blocked by the particle blocking part 41a flows into the adhesive. Acts as part 41b.

  In the embodiment described above, the hole 41 is formed in the electrode 4 included in the circuit member 2, but the hole 14 similar to the hole 41 is formed in the electrode 14 included in the circuit member 12. Good. Alternatively, a hole similar to the hole 41 may be formed only in the electrode 14 without forming a hole in the electrode 4.

  DESCRIPTION OF SYMBOLS 1 ... Connection structure, 2 ... Circuit member, 3 ... Board | substrate, 4 ... Electrode, 5 ... Anisotropic conductive adhesive, 41 ... Hole part, 41a ... Particle damming part, 41b ... Adhesive inflow part, 51 ... Conductivity Particle, 52 ... adhesive component.

Claims (6)

A circuit member comprising a substrate and an electrode formed on one surface side of the substrate, and bonded to another substrate via an anisotropic conductive adhesive containing conductive particles and an adhesive component,
The electrode is formed with a hole into which the anisotropic conductive adhesive flows during crimping ,
The hole portion includes a particle damming portion that dams the conductive particles when the anisotropic conductive adhesive flows in, and even when the conductive particles are dammed by the damming portion. A circuit member comprising an adhesive inflow portion that allows inflow . The hole is characterized by being formed with a depth extending through the electrode, according to claim 1 Symbol mounting circuit member. The hole is characterized by being formed to a depth reaching the interior of the substrate, according to claim 1 or 2 circuit member according. The hole is characterized in that it is formed at a depth which penetrates the substrate, the circuit member according to any one of claims 1-3. A connection structure formed by pressure-bonding circuit members each including a substrate and an electrode formed on one side of the substrate via an anisotropic conductive adhesive containing conductive particles and an adhesive component,
At least one of the electrodes of the circuit member is formed with a hole into which the anisotropic conductive adhesive has flowed during crimping ,
The hole has a particle damming portion in which the conductive particles are dammed when the anisotropic conductive adhesive flows, and the bonding even when the conductive particles are dammed by the damming portion. An adhesive inflow portion that allows inflow of the agent component is formed . A method for producing a connection structure comprising a substrate and a circuit member comprising an electrode formed on one side of the substrate, and bonded by an anisotropic conductive adhesive containing conductive particles and an adhesive component. And
Wherein forming a hole having a particle blocking portion on at least one of the electrodes and the adhesive inflow portion of the circuit member, the allowed to flow into anisotropic conductive adhesive into the hole portion when the crimping, the anisotropic When the conductive adhesive flows, the conductive particles are dammed by the damming portion, and even when the conductive particles are dammed by the damming portion, the adhesive component is caused to flow by the inflow portion. A method for manufacturing a connection structure, which is characterized.

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