JP2008248044A - Anisotropic electroconductive adhesive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anisotropic electroconductive adhesive material surely carrying out conduction and connection at a low electric resistance value without causing short-circuiting even in conduction and connection in a high-definition device in which connection terminals are formed into fine pitches. <P>SOLUTION: The anisotropic electroconductive adhesive material 2 formed on a base sheet 1 as a separator is composed by including a mesh member 23 as a particle movement regulating member for regulating the movement of electroconductive particles 22 in a binder resin layer 21 starting softening and flowing by being pressurized while being heated in the binder resin layer 21 in which the electroconductive particles 22 are uniformly dispersed and held. The mesh member 23 is formed of a thermoplastic resin material melting in the binder resin layer 21 without adversely affecting an adhesion holding ability of the binder resin layer 21 even by melting in a process of heating the binder resin layer 21 to a curing temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an anisotropic conductive adhesive used when conducting connection between connection terminals.

  In recent years, display devices such as liquid crystal display panels have high-density pixels in order to display high-definition images such as so-called high-definition images, and accordingly, driver chip for driving the pixels and lead wiring connection terminal pitch Is also miniaturized.

In the conductive connection between the connection terminal of the high-definition display device as described above and the highly integrated driver chip or external wiring board, the anisotropic conductive adhesive as shown in Patent Document 1 is reliable and It is widely used because it is advantageous in terms of workability.
JP 11-329542 A

  When conducting connection between the connection terminals using an anisotropic conductive adhesive, the anisotropic conductive adhesive is sandwiched between the corresponding connection terminals, and heated while being heated to about 180 ° C. by a thermocompression bonding tool. At the time of crimping, the conductive particles flow from the facing portion of the connection terminal having a relatively high pressure to the adjacent connection terminals having a low pressure.

  When the conductive particles flow out between the opposing connection terminals, not only does the number of conductive particles sandwiched between the connection terminals to be connected decrease, the electrical resistance value of the conductive connection increases, but also the connection terminal pitch increases. In a high-definition device that has been miniaturized (fine pitch), there is a problem in that adjacent connection terminals are short-circuited by conductive particles that have moved between adjacent connection terminals.

  An object of the present invention is to provide an anisotropic conductive adhesive that can reliably conduct a connection with a low electric resistance value without causing a short circuit even in a conduction connection in a high-definition device in which connection terminals have a fine pitch.

  The anisotropic conductive adhesive according to claim 1 of the present invention includes a binder resin layer made of a thermosetting resin material, a plurality of conductive particles dispersed and held in the binder resin layer, and the binder resin layer. The thermosetting resin material is formed of a material having a melting point that is higher than the temperature at which the thermosetting resin material softens and exhibits fluidity and lower than the curing temperature of the thermosetting resin material, and the binder resin layer is softened And a particle movement regulating member that regulates the movement of the conductive particles accompanying the flow of the binder resin layer by being pressurized while being heated to a temperature exhibiting fluidity. .

  The anisotropic conductive adhesive according to claim 2 is the anisotropic conductive adhesive according to claim 1, wherein the particle movement restricting member is formed by knitting a yarn made of a thermoplastic resin material, and the binder It is a mesh cloth material included in the resin layer.

  The anisotropic conductive adhesive according to claim 3 is the anisotropic conductive adhesive according to claim 1, wherein the particle movement restricting member is formed on one surface of the binder resin layer holding the conductive particles. The braking layer is formed to be an uneven surface in which a plurality of protrusions having a triangular cross section are juxtaposed in parallel and the surface in contact with the binder resin layer is provided in an overlapping manner.

  The anisotropic conductive adhesive according to claim 4 is the anisotropic conductive adhesive according to claim 1, wherein the particle movement restricting member is formed on one surface of the binder resin layer holding the conductive particles. The braking layer is a braking layer which is provided in a superimposed manner and has a plurality of holes drilled in the thickness direction in a predetermined arrangement.

  According to the anisotropic conductive adhesive of the present invention, a reliable conductive connection is obtained, and the reliability of the conductive connection is improved.

(First embodiment)
Fig.1 (a) is typical sectional drawing which shows the anisotropic conductive adhesive sheet as 1st Embodiment of this invention.
The anisotropic conductive adhesive sheet of this embodiment is configured by molding an anisotropic conductive adhesive 2 on one surface of a base sheet 1 as a separator made of PET (polyethylene terephthalate).

  The anisotropic conductive adhesive 2 uses a thermosetting epoxy resin as a material for the binder resin layer 21, and includes a plurality of conductive particles 22 and a mesh member 23 included in the binder resin layer 21. It has become.

  The conductive particles 22 are prepared by making the surface of the acrylic resin beads a gold plating process and having an average particle diameter of about 5 μm.

  The mesh member 23 uses a thermoplastic resin material that can be uniformly melted in the epoxy resin that is the material of the binder resin layer 21 and does not adversely affect the physical properties of the binder resin, and the resin fibers spun using the thermoplastic resin material as a predetermined material. It is formed by weaving to the pitch. The thermoplastic resin material used for the mesh member 23 is a temperature higher than the temperature at which the thermosetting resin material of the binder resin layer softens and exhibits fluidity, and is lower than the curing temperature of the thermosetting resin material. It consists of a resin material having its melting point in the temperature range. As the thermoplastic resin material, propylene / ethylene / butadiene block copolymer, polystyrene spylene acrylic, or the like can be used.

  FIG. 1B is a schematic plan view showing the anisotropic conductive adhesive of this embodiment viewed through the binder resin layer 21. The pitch (transverse pitch) p1 between the warp yarns 231 and the pitch (vertical pitch) p2 between the weft yarns 232 of the mesh member 23 are set according to the use, that is, the connection terminal pitch of the device to be conductively joined. For example, in the case of an anisotropic conductive adhesive used for conductively bonding a driver chip to a lead wiring terminal of a high-definition liquid crystal display panel by a COG (Chip On Glass) method, the pitch between wiring terminals is about 20 μm. Therefore, it is preferable to set the longitudinal pitch of the mesh member 23, that is, the lateral pitch p1 to about 20 μm.

  The anisotropic conductive adhesive having the above-described configuration can be manufactured by various methods. Among them, the roll coater method is preferably used. In the case of this roll coater method, first, the mesh member 23 is manufactured using the thermoplastic resin material as described above, and it is easily obtained by roll coating a binder resin material in which the conductive particles 21 are dispersed and mixed. .

  Next, a perspective view of FIG. 2 and FIG. 3 (a) to FIG. Description will be made based on the schematic cross-sectional view of (c).

  As shown in FIG. 2, the thermocompression bonding apparatus used in the thermocompression bonding process includes a table 3 that supports a workpiece and a thermocompression bonding tool 4 that moves up and down with respect to the workpiece 3. The liquid crystal display panel 5 is set. The liquid crystal display panel 5 has a liquid crystal sandwiched between a pair of glass substrates 51 and 52, and a signal for driving the liquid crystal is provided in a protruding portion 521 that protrudes from a corresponding end surface of the other glass substrate 61 of one glass substrate 52. A wiring circuit 53 for supplying a voltage is provided, and the driver chip 6 is mounted on the wiring circuit 53.

  First, the anisotropic conductive adhesive 2 obtained by cutting the anisotropic conductive adhesive sheet to a required size and peeling the base sheet 1 is mounted on the driver chip on the protrusion 521 of one glass substrate 52 of the liquid crystal display panel 5. Place in position. At this time, as shown in FIG. 3A, the anisotropic conductive adhesive layer 2 is placed while positioning so that the warp 231 of the mesh member 23 is positioned between the wiring terminals 531 of the liquid crystal display panel 5. To do.

  Next, the driver chip 6 is placed on the anisotropic conductive adhesive layer 2 while being aligned. At this time, as shown in FIG. 3A, the wiring terminals 531 of the liquid crystal display panel 5 and the corresponding terminal electrodes 61 of the driver chip 6 are arranged to accurately face each other with the anisotropic conductive adhesive 2 interposed therebetween. Align as follows.

  Next, the thermocompression bonding tool 4 incorporating the heater 41 is lowered while the heater 41 is turned on, and the front end surface of the pressing head 42 is brought into contact with the upper surface of the driver chip 6 to start thermocompression bonding. As a result, as shown in FIG. 3B, the binder resin 21 having fluidity is heated and softened through the driver chip 6 and is pressed between the wiring terminals 531 and the terminal electrodes 61 facing each other. It flows between the adjacent wiring terminals 531 and 531 which are not pressed and between the adjacent terminal electrodes 61 and 61. As the binder resin 21 flows, the conductive particles 22 also follow and move. However, the mesh member 23 having a melting point higher than the temperature indicating the fluidity of the binder resin 21 is still softened at that temperature. Therefore, the movement is restricted by the mesh member 23. As a result, as shown in the drawing, most of the conductive particles 22 are collected in a region corresponding to the mesh where the mesh yarns 231 and 232 do not exist. The region corresponding to the mesh is a region where the corresponding wiring terminal 531 and the terminal electrode 61 face each other.

  Thereafter, when the thermocompression bonding tool 4 (see FIG. 2) is lowered to a predetermined maximum stroke position, as shown in FIG. 3 (c), the mesh member 23 made of thermoplastic resin is heated to the melting point or higher and the binder is heated. A state is obtained in which the resin 21 is melted in the resin 21 and most of the conductive particles 22 are selectively pressed and sandwiched between the corresponding wiring terminal 631 and the terminal electrode 71.

  As described above, since the anisotropic conductive adhesive sheet of the present embodiment is integrally formed in the binder resin layer 21 together with the conductive particles 22, the mesh member 23 is a member that regulates the follow-up movement of the conductive particles 22. When the anisotropic conductive adhesive 2 is heated and pressed in the thermocompression bonding process, the movement of the conductive particles 22 following the softened and rolled binder resin 21 is suppressed, and as a result, the corresponding wiring A necessary and sufficient amount of conductive particles 22 is selectively sandwiched and held between the terminal 531 and the terminal electrode 61, and a conductive connection state having a small electric resistance value and excellent reliability without a short circuit is obtained.

  Further, since the mesh member 23 is formed of a thermoplastic resin that melts into the binder resin in the process of heating the binder resin to the curing temperature and does not adversely affect the adhesion effect thereof, the adhesive strength necessary for the binder resin can be obtained. Sufficiently secured.

(Second Embodiment)
Next, 2nd Embodiment of this invention is described based on Fig.4 (a), (b). FIG. 4A is a perspective view showing the internal configuration of the anisotropic conductive adhesive sheet of the present embodiment through a binder resin layer, and FIG. 4B is a schematic cross-sectional view taken along line BB. . In addition, the same code | symbol is attached | subjected about the component same as the said 1st Embodiment, and the description is abbreviate | omitted.

  The anisotropic conductive adhesive sheet of this embodiment is formed by forming an anisotropic conductive adhesive 7 having a two-layer structure on one side surface of a base sheet 1. The anisotropic conductive adhesive 7 has a two-layer structure in which a conductive adhesive layer 72 is laminated on a braking layer 71 as a particle movement regulating member, and the conductive adhesive layer 72 is in a binder resin 721 made of a thermosetting resin. The conductive particles 722 are dispersed and held substantially uniformly.

  As with the mesh member 23 of the first embodiment, the braking layer 71 is at a temperature higher than the temperature at which the thermosetting resin material of the binder resin layer softens and exhibits fluidity, and the thermosetting resin material is cured. A resin material having a melting point in a temperature range lower than the temperature, and a thermoplastic resin that melts into the binder resin 721 while the binder resin 721 is heated up to its curing temperature and does not adversely affect its adhesion holding effect. The surface that is formed using and in contact with the conductive adhesive layer 72 is formed as an uneven surface in which a plurality of protrusions 711 having a triangular cross section are arranged in parallel. In this case, the juxtaposed pitch p3 of the protrusions 711 is set in a range larger than the average particle diameter of the conductive particles 722 and smaller than the juxtaposition pitch of connection terminals to be electrically connected.

  As described above, the anisotropic conductive adhesive 7 has a two-layer structure of the braking layer 71 and the conductive adhesive layer 72 as a particle movement restricting member, whereby the anisotropy according to the present invention including the particle movement restricting member is provided. The conductive adhesive 7 can be easily manufactured. That is, the anisotropic conductive adhesive 7 is formed by forming the braking layer 71 on the base sheet 1 in a predetermined shape by, for example, the injection method and laminating the conductive adhesive layer 72 thereon by the roll coating method or the like. Easy to get.

  When the anisotropic conductive adhesive sheet of this embodiment is used in the thermocompression bonding process, the anisotropic conductive adhesive 7 is aligned with the extending direction of the protrusions 711 parallel to the extending direction of the connection terminals to be connected. Is placed on one of the connection terminal arrays.

  When the placed anisotropic conductive adhesive 7 is pressed while being heated by a thermocompression bonding tool, the conductive particles 722 first enter the grooves 712 between the adjacent protrusions 711 and 711 in the braking layer 71. The conductive particles 722 entering the grooves 712 are not restricted from moving in the extending direction of the protrusions 711, but are restricted from moving in the direction perpendicular to the extending direction, that is, in the direction in which the connection terminals are arranged (array). The

  In a state where most of the conductive particles 722 have entered the groove 712, the anisotropic conductive adhesive 7 is further heated and pressed by a thermocompression bonding tool, so that the braking layer 71 is melted in the binder resin 721. Thereafter, the binder resin 721 in which the thermoplastic resin of the braking layer material is melted is cured. In this cured state, the conductive particles 722 are distributed substantially uniformly with respect to the juxtaposed direction of the protrusions 711 whose movement is restricted (array direction of the connection terminals).

  Accordingly, the corresponding connection terminals to be conductively connected are necessary and are securely connected in a state where a sufficient number of conductive particles are held and held, and insulation between adjacent connection terminals is ensured.

(Third embodiment)
Next, a third embodiment of the present invention will be described based on FIGS. 5 (a) and 5 (b). FIG. 5A is a perspective view showing the internal configuration of the anisotropic conductive adhesive sheet of the present embodiment through a binder resin layer, and FIG. 5B is a schematic cross-sectional view taken along line BB. . In addition, the same code | symbol is attached | subjected about the component same as the said 1st Embodiment, and the description is abbreviate | omitted.

  An anisotropic conductive adhesive 8 as a third embodiment includes a binder resin on a braking layer 81 in which a plurality of through holes 811 for restricting the movement of conductive particles are formed in a predetermined arrangement in the thickness direction. A conductive adhesive layer 82 having the same structure as the conductive adhesive layer 72 of the second embodiment, in which conductive particles 822 are uniformly dispersed and held in 821, is laminated.

  Like the braking layer 71 of the second embodiment, the braking layer 81 has a temperature higher than the temperature at which the thermosetting resin material of the binder resin layer softens and exhibits fluidity, and the curing temperature of the thermosetting resin material. A resin material having a melting point in a lower temperature range, and the binder resin 821 of the conductive adhesive layer 82 melts into the binder resin 821 in the process of being heated to the curing temperature and does not adversely affect the adhesion holding effect. It is formed using a plastic resin.

The through holes 811 are formed in a matrix arrangement, and at least one of the arrangement pitches p4 is preferably set to the same dimension as the pitch of the connection terminals to be conductively connected, and the inner diameter D is For the average particle diameter d of the conductive particles 822
3d ≦ D ≦ 5d
It is preferable to set the degree.

  In the anisotropic conductive adhesive material 8 of this embodiment configured as described above, the braking layer 81 and the conductive adhesive layer 82 are individually manufactured by a method suitable for each, and the completed conductive layer 8 is formed into a conductive layer. By attaching the adhesive layer 82, it can be easily obtained.

  When the anisotropic conductive adhesive material 8 of this embodiment is used in the thermocompression bonding process, the row of through holes 811 arranged at a pitch p4 set to the same dimension as the pitch of the connection terminal array to be joined is the corresponding connection terminal. The anisotropic conductive adhesive 8 is placed so as to be properly aligned.

  When the placed anisotropic conductive adhesive 8 is pressed while being heated by a thermocompression bonding tool, each conductive particle 822 enters into a through hole 811 close to each other. In a state where most of the conductive particles 822 have entered the through hole 811, the brake layer 81 is melted in the binder resin 821 by being further pressurized while being heated by the thermocompression bonding tool. The binder resin 821 in which the material is melted is cured. In this cured state, most of the conductive particles 822 whose follow-up movement is restricted by the through hole 811 are held between the opposing connection terminals. As a result, the corresponding connection terminals to be connected to each other are securely connected in a state in which a sufficient amount of conductive particles are necessary and held, and insulation between adjacent connection terminals is ensured.

The present invention is not limited to the above embodiment.
For example, in the first embodiment shown in FIG. 1, the mesh pitch p1 of the mesh member 23 is set, and in the third embodiment shown in FIG. 5, the arrangement pitch p4 of the through holes 811 is set to the connection terminal pitch to be conductively connected. The pitches p1 and p4 can be set smaller than the connection terminal pitch. This increases the braking effect that restricts the movement of the conductive particles that follow the rolled binder resin, and the distribution of the conductive particles held in the hardened binder tree is made more uniform. In positioning with respect to the connection terminal row when the adhesive is placed on the conductive bonding portion, a large allowable width can be expected, and the conductive bonding work is facilitated.

  In the first embodiment, the anisotropic conductive adhesive of the present invention is used for conductive bonding between the driver chip and the wiring terminal of the drive circuit disposed on the glass substrate of the liquid crystal display panel. The anisotropic conductive adhesive of the present invention can also be suitably used for conductive bonding between wiring boards such as a wiring board such as a flexible wiring board and a wiring terminal of a drive circuit board. For the conductive bonding between the wiring boards, the follow-up movement of the conductive particles is restricted in one direction (the direction in which the grooves 711 are arranged) as in the anisotropic conductive adhesive 7 as the second embodiment shown in FIG. An anisotropic conductive adhesive is more preferable.

  Furthermore, as an example of compromise between the first embodiment shown in FIG. 1 and the third embodiment shown in FIG. 5, a braking layer 81 provided with a through hole 811 is integrated into a binder resin 821 like the mesh member 24 in FIG. 1. May be included.

  In addition, the hole provided in the braking layer 81 in the third embodiment may not be a through hole but a recess having a depth that can effectively restrict the follow-up movement of the conductive particles.

(A) is typical sectional drawing which shows the anisotropic conductive adhesive sheet as 1st Embodiment of this invention, (b) is a top view which sees through and shows the principal part structure. It is a perspective view which shows the thermocompression bonding process using the anisotropic conductive adhesive material of the said 1st Embodiment. (A)-(c) is each typical sectional drawing for each step which showed the thermocompression bonding operation | movement in the said thermocompression bonding process in order of a step, respectively. (A) is a perspective view which shows the anisotropic conductive adhesive sheet as 2nd Embodiment of this invention, (b) is the BB sectional drawing. (A) is a perspective view which shows the anisotropic conductive adhesive sheet as 3rd Embodiment of this invention, (b) is the BB sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base sheet 2 Anisotropic conductive adhesive 21 Binder resin layer 22 Conductive particle 23 Mesh member 3 Table 4 Thermocompression bonding tool 41 Heater 42 Press head 5 Liquid crystal display panel 51, 52 Glass substrate 53 Wiring circuit 531 Wiring terminal 6 Driver chip 61 Terminal electrode 7, anisotropic conductive adhesive 71 braking layer 711 ridge 712 groove 72 conductive adhesive layer 8 anisotropic conductive adhesive 81 braking layer 811 through hole 82 conductive adhesive layer

Claims (4)

A binder resin layer made of a thermosetting resin material;
A plurality of conductive particles dispersed and held in the binder resin layer;
The binder resin layer is formed of a material having a melting point that is higher than the temperature at which the thermosetting resin material is softened and exhibits fluidity and lower than the curing temperature of the thermosetting resin material, A particle movement regulating member that regulates the movement of the conductive particles accompanying the flow of the binder resin layer by being pressurized while being heated to a temperature at which the resin layer is softened and exhibits fluidity, An anisotropic conductive adhesive.   2. The anisotropic conductive adhesive according to claim 1, wherein the particle movement regulating member is a mesh cloth material formed by knitting a yarn made of a thermoplastic resin material and included in the binder resin layer. .   The particle movement restricting member is arranged to overlap with one surface of the binder resin layer holding the conductive particles, and a plurality of protrusions having a triangular cross section in parallel with the surface in contact with the binder resin layer are arranged in parallel. The anisotropic conductive adhesive according to claim 1, wherein the anisotropic conductive adhesive is a braking layer formed on the uneven surface.   The particle movement restricting member is a braking layer that is superimposed on one surface of a binder resin layer that holds the conductive particles, and a plurality of holes are formed in a predetermined arrangement in the thickness direction. The anisotropic conductive adhesive according to claim 1.

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