JP2007039519A - Anisotropic conductive adhesive and electronic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hardly cause a short circuit and breaking even if moisture in an external atmosphere is infiltrated into an anisotropic conductive adhesive in a mounting structure of a semiconductor apparatus using an anisotropic conductive adhesive. <P>SOLUTION: The anisotropic conductive adhesive 21 is obtained by dispersing a conductive particle 23 and a water-absorbing particle 24 into an insulating adhesive 22. Moisture infiltrated into the anisotropic conductive adhesive 21 is absorbed in the water-absorbing particle 24 and a short circuit and breaking of the wiring 12 of a circuit board 11 caused by moisture hardly occur. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an anisotropic conductive adhesive and an electronic device using the same.

  For example, a semiconductor device mounting structure made of LSI or the like includes a semiconductor device mounted on a circuit board via an anisotropic conductive adhesive (see, for example, Patent Document 1). In this case, the anisotropic conductive adhesive is obtained by dispersing conductive particles in an insulating adhesive made of epoxy resin or the like, and the lower surface of the semiconductor device is circuit board by the insulating adhesive. The connection electrode provided on the lower surface of the semiconductor device is electrically connected to the wiring (connection terminal) provided on the upper surface of the circuit board by the conductive particles.

JP-A-9-191026

  By the way, an insulating adhesive made of an epoxy resin or the like of an anisotropic conductive adhesive is not completely moisture-resistant (non-moisture permeable, non-hygroscopic), so moisture in the external atmosphere is applied to the wiring portion of the circuit board. If so, the ionic impurities adhering to the circuit board wiring may be hydrolyzed by the infiltrated moisture, causing a short circuit between the circuit board wirings or corroding the circuit board wiring. There was a problem that there was something.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an anisotropic conductive adhesive capable of preventing a short circuit or disconnection from occurring even when moisture in an external atmosphere enters, and a highly reliable electronic device. And

In order to achieve the above object, the present invention is characterized in that an anisotropic conductive adhesive is obtained by dispersing a water-absorbing material in an insulating adhesive.
In order to achieve the above object, according to the present invention, in an electronic device, an electrical connection between electronic components is achieved using an anisotropic conductive adhesive in which a water-absorbing material is dispersed in an insulating adhesive. It is characterized by being made.

According to this invention, since the anisotropic conductive adhesive is made by dispersing the water-absorbing material in the insulating adhesive, even if moisture in the external atmosphere enters the anisotropic conductive adhesive, The infiltrated moisture can be absorbed by the water-absorbing material. Therefore, it is possible to prevent the occurrence of short circuit and disconnection due to the moisture.
In addition, according to the present invention, the electrical connection between the electronic components is made using the anisotropic conductive adhesive in which the water-absorbing material is dispersed in the insulating adhesive. High electronic equipment can be manufactured.

  FIG. 1 shows a cross-sectional view of a main part of an example of a semiconductor device mounting structure using an anisotropic conductive adhesive as one embodiment of the present invention. In this semiconductor device mounting structure, a semiconductor device 1 made of LSI or the like is mounted on a circuit board 11 via an anisotropic conductive adhesive 21. Among these, the semiconductor device 1 has a structure in which a plurality of connection electrodes 3 are provided on the periphery of the lower surface of the semiconductor body 2. Wirings (connection terminals) 12 are provided at predetermined locations on the upper surface of the circuit board 11.

  The anisotropic conductive adhesive 21 is formed by dispersing conductive particles 23 and water-absorbing particles 24 in an insulating adhesive 22. Among these, the insulating adhesive 22 is made of a thermosetting resin, a thermoplastic resin, a synthetic rubber, or the like. In particular, when heat resistance is required, a thermosetting resin such as an epoxy resin is used. The conductive particles 23 are made of nickel particles, a nickel nucleus whose surface is covered with a gold plating film, a resin nucleus whose surface is covered with a nickel plating film or a gold plating film, and the like.

  The water-absorbing particles 24 absorb water of several hundred to thousand times its own weight, and have high water-absorbing polymer having water retention property that a gel formed by swelling due to absorption of water does not separate even by some pressure. Structurally, the electrolyte water-absorbing polymer having an ionic group or a hydrophilic polymer having many hydroxyl groups is slightly crosslinked. The conventional anisotropic conductive adhesive did not contain the water absorbing particles 24.

Specific examples of the material for the water-absorbing particles 24 include a slightly cross-linked water-soluble polymer such as carboxymethyl cellulose, polyvinyl alcohol, and polyacrylic acid. In particular, a sodium polyacrylate type having a sodium carboxylate group (—COO—Na ⁺ ) as an ionic group is preferred from the viewpoint of water absorption performance (swelling ratio), ease of industrial production, and cost.

The principle of water absorption in this case is explained as follows. The state before water absorption has a three-dimensional network structure in which long molecular chains of the polymer are entangled and the molecules are partially cross-linked. This molecular chain is hydrophilic and has a sodium carboxylate group that is easily ionized into positive ions and negative ions in water. Therefore, if water is present, the network structure spreads in an attempt to dissolve in water. When water enters the network structure, the sodium ion (Na ⁺ ) in the sodium carboxylate group is dissociated, and the carbonyl group (—COO—) that is the residue remains in the molecular chain. Since these carbonyl groups are negative ions, they repel each other electrically, further expanding the network structure. Then, moisture is further absorbed and retained in the spread network structure.

  The lower surface of the semiconductor device 1 is bonded to the upper surface of the circuit board 11 via the insulating adhesive 22 of the anisotropic conductive adhesive 21, and the connection electrode 3 is different from the wiring 12 of the circuit board 11. It is mounted on the circuit board 11 in a state of being electrically connected through the conductive particles 23 of the isotropic conductive adhesive 21.

  Thus, in this semiconductor device mounting structure, since the anisotropic conductive adhesive 21 is formed by dispersing the conductive particles 23 and the water-absorbing particles 24 in the insulating adhesive 22, the external atmosphere Even when the moisture enters the anisotropic conductive adhesive 21, the moisture that has entered can be absorbed by the water-absorbing particles 24, so that the wiring 12 on the circuit board 11 is short-circuited or disconnected due to the moisture. It can be made difficult to occur.

  FIG. 2 shows an electronic device in which components are connected using such an anisotropic conductive adhesive 21 in which conductive particles 23 and water-absorbing particles 24 are dispersed in an insulating adhesive 22. 1 is a diagram illustrating an example of a cross-sectional view of a driver connection portion of a liquid crystal display device.

  The liquid crystal display device 40 includes a liquid crystal panel unit 401 (here, a simple matrix panel for simplicity), and the liquid crystal panel unit 401 is filled with liquid crystal 405 in a space surrounded by a lower substrate 402, an upper substrate 403, and a sealant 404. The lower polarizing plate 406 and the upper polarizing plate 407 are attached to the outside of the lower substrate 402 and the upper substrate 403, respectively.

  An ITO wiring 12 a is patterned on the lower substrate 402 of the liquid crystal panel 401, and the anisotropic conductive adhesive 21 is formed by dispersing the conductive particles 23 and the water absorbing particles 24 in the insulating adhesive 22. Is used to connect the silver wiring portion 3a of the TAB 1a on which the driver IC 2a is mounted. (Similarly, ITO wirings 12b, 12c,... Are also patterned on the upper substrate 403, and are connected to a TAB (not shown) in a direction perpendicular to the paper (not shown).)

  Here, an example of a liquid crystal display device using TAB is shown; however, it can be used for connection of not only TAB but also a liquid crystal display device using a COG connection technology, and not only a display device but also a general electronic device. Needless to say.

  Thus, the electrical connection between the electronic components is made using the anisotropic conductive adhesive 21 in which the conductive particles 23 and the water absorbing particles 24 are dispersed in the insulating adhesive 22. In the electronic device characterized in that, even if moisture in the external atmosphere enters the anisotropic conductive adhesive 21, the moisture that has entered can be absorbed by the water-absorbing particles 24. Higher ones can be manufactured.

Sectional drawing of the principal part of an example of the mounting structure of the semiconductor device using the anisotropic conductive adhesive as one Embodiment of this invention. Sectional drawing of the electronic device (driver connection part of a liquid crystal display device) using the anisotropic conductive adhesive as one Embodiment of this invention.

Explanation of symbols

1 Semiconductor Device 1a TAB
2 Semiconductor body 2a Driver IC
3 connection electrode 3a silver wiring part 11 circuit board 12 wiring (connection terminal)
12a, 12b, 12c ITO wiring 21 Anisotropic conductive adhesive 22 Insulating adhesive 23 Conductive particle 24 Water absorbing particle 40 Liquid crystal display device 401 Liquid crystal panel unit 402 Lower substrate 403 Upper substrate 404 Sealing material 405 Liquid crystal 406 Lower polarization Plate 407 Upper polarizing plate

Claims (5)

  An anisotropic conductive adhesive comprising a water-absorbing material dispersed in an insulating adhesive.   2. The anisotropic conductive adhesive according to claim 1, wherein the water absorbing material is made of a water absorbing polymer.   2. The anisotropic conductive adhesive according to claim 1, wherein the anisotropic conductive adhesive is a film.   2. The anisotropic conductive adhesive according to claim 1, wherein the anisotropic conductive adhesive is pasty.   An electronic device characterized in that an electrical connection is made between electronic components using an anisotropic conductive adhesive in which a water-absorbing material is dispersed in an insulating adhesive.

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