JP2008016690A - Connection structure for connecting electrode of substrate and connection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection structure for connecting electrodes of substrates and a connection method, which need no formation of terminals having a specific cross-sectional shape, and attain electric connection between electrodes at a low cost with a high reliability by a simple manufacturing process regardless of the type and size of substrates. <P>SOLUTION: A rigid wiring board 1 is provided with electrodes 3, and a flexible wiring board 2 is provided with electrodes 4. The widths d of the ends of these electrodes 3 and 4 are 100 μm or below, preferably 30 μm or below. The electrodes 3 and 4 are aligned with each other, with the end faces thereof abutted against each other and in contact with each other. In this state, the wiring boards 1 and 2 are joined together by an insulating adhesive 5 arranged between them. The insulating adhesive 5 is pressurized and heated to be cured to join the wiring boards 1 and 2 together after the wiring boards 1 and 2 are aligned. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a substrate electrode connection structure and a connection method in which electrodes of a substrate such as a rigid wiring board, a flexible wiring board, and a glass substrate are electrically connected using a non-conductive adhesive.

  Conventionally, for example, when conductively connecting electrodes of a rigid wiring board and a flexible wiring board, an electrically conductive adhesive material such as an anisotropic conductive film (hereinafter referred to as ACF) or a conductive paste is often used. The conductive adhesive material is a material in which conductive particles are dispersed and contained in an insulating adhesive, and electrical connection is ensured by sandwiching the conductive particles between opposing electrodes.

  However, in the case of conductive connection using a conductive adhesive material, there is a limit to the number of conductive particles interposed between both electrodes. That is, when the number of conductive particles is large, a short circuit between adjacent electrodes or insulation deterioration is caused. For this reason, there exists a problem that a contact resistance value becomes high especially when an electrode pitch becomes narrow. In addition, since the ACF for narrow pitch electrodes needs to contain fine and uniform conductive particles in a dispersed manner, there is also a problem that the material cost is increased.

  Therefore, recently, a connection method that does not use a conductive adhesive material has been proposed for electrical connection between two wiring boards. For example, in the conventional connection method described in FIG. 3 of Patent Document 1, a protrusion is formed on a laminated body of a conductive layer and an insulating adhesive layer by embossing, and another conductive material is formed on the tip side of the protrusion of the conductive layer. A layer is disposed so that the tip of the protrusion is brought into contact with the other conductive layer, and the conductive layer and the other conductive layer are bonded and fixed by an insulating adhesive layer around the protrusion. As a result, both conductive layers are bonded and fixed by an insulating adhesive layer while being in electrical contact with the other conductive layer at the protruding portion provided on one conductive layer, so that the electrical connection can be made with a low load. Realized. In this way, the wiring boards (conductive layers) can be joined together using a non-conductive adhesive that does not contain conductive particles as a binder.

  Moreover, in patent document 2, the non-conductive adhesive agent of the said flexible wiring board is hardened by pressurizing and heating the flexible wiring board which does not provide especially the protrusion etc. with the tool which has an uneven | corrugated shape, A method has been proposed in which the connection state is the same as that of the prior art of Document 1.

  Furthermore, in Patent Document 3, a film substrate having a wiring pattern on the surface, a semiconductor chip having an electrode on the surface and mounted on the film substrate, and a film substrate or semiconductor chip previously applied, after the semiconductor chip is mounted A connection structure having an insulating resin filled between a film substrate and a semiconductor chip is disclosed. In this connection structure, the wiring pattern has a projecting portion having a cross-sectional shape that tapers toward the electrode of the semiconductor chip, and the projecting portion bites into the electrode so that the wiring pattern and the electrode are electrically connected. . Thus, in patent document 3, a protrusion part bites into an electrode (embodiment bump electrode), and the protrusion part and the electrode are connected. Patent Document 3 describes that the protrusion and the electrode may be thermocompression bonded.

  Furthermore, Patent Document 4 discloses a joined body in which terminals of a pair of members to be joined having a plurality of terminals are ultrasonically joined and a gap between the terminals is filled with an insulating resin. .

JP 2002-97424 A (FIG. 3) JP-A-9-281520 JP 2004-342903 A JP 2005-183589 A

  However, in the case of the prior art described in Patent Document 1, an embossing process or equipment dedicated to the embossing process is required, which raises a problem of increasing the material price.

  Further, in the case of the prior art of Patent Document 2, a large load is required to deform the conductive layer of the flexible wiring board, so that the other-side wiring board is destroyed particularly when the other side is a thin glass substrate. There is a risk. Moreover, since it is necessary to pressurize with a very high load when the number of electrodes increases, there is a problem that it is not possible to cope with commercial facilities.

  Furthermore, both of the known techniques of Patent Documents 1 and 2 have a drawback in that they are limited to wiring boards made of a flexible material such as a flexible wiring board in order to deform the wiring layer.

  Furthermore, in the prior art described in Patent Document 3, a bump electrode is provided on the semiconductor chip, and the protrusion having a cross-sectional shape that tapers toward the bump electrode of the semiconductor chip so that the wiring pattern easily bites into the electrode of the semiconductor chip. Therefore, there is a problem that the manufacturing process becomes complicated in order to form these shapes. Further, it is necessary to provide a bump for the protrusion to bite into one of the electrodes.

  Furthermore, in the prior art described in Patent Document 4, the terminals are ultrasonically bonded to each other. However, since the ultrasonic waves are hardly transmitted to the terminals (electrodes) to be bonded, the terminals are applied to the bonding between the resin substrates. Can not do it. Further, when the member to be joined is increased in size, ultrasonic waves are not transmitted uniformly and joining cannot be performed. For ultrasonic bonding, a large capital investment is required, for example, an expensive ultrasonic unit or the like is installed and equipment having high rigidity is required.

  The present invention has been made in view of such problems, and it is not necessary to form a terminal having a specially shaped cross section, and it is possible to reduce the number of substrates by a simple manufacturing process regardless of the type and size of the substrate. It is an object of the present invention to provide a substrate electrode connection structure and a connection method capable of obtaining electrical connection between electrodes with high cost and high reliability.

  In the substrate electrode connection structure according to the present invention, the first and second substrates each having an electrode having a tip width of 100 μm or less are provided between the electrodes of each substrate in a state in which the tips of the electrodes are in contact with each other. The electrodes of the first and second substrates are electrically connected to each other by being joined by the insulating adhesive.

  The substrate electrode connection method according to the present invention includes a step of forming a first electrode having a tip width of 100 μm or less on the surface of the first substrate, and a step of covering the first electrode with the first electrode. A step of providing an insulating adhesive on the surface, a step of forming a second electrode having a tip width of 100 μm or less on the surface of the second substrate, and the first and second substrates as the first and second substrates. And a step of joining the first substrate and the second substrate with the insulating adhesive.

  In the present invention, the tip width of the electrode is preferably 30 μm or less. Moreover, it is preferable that the front end surface of the said electrode is a plane.

  According to the present invention, substrates such as wiring boards intentionally formed thin with an electrode tip width of 100 μm or less are bonded and fixed using an insulating adhesive, and the electrodes are brought into contact with each other at their tip surfaces. Since the electrodes are electrically connected to each other, the electrodes can be electrically connected easily and at low cost.

  In other words, in the present invention, there is no need to emboss the wiring board, and there is no need to connect the electrodes by providing a protruding portion with a tapered tip and causing the protruding portion to bite into the bump electrode. The electrodes and the electrodes need not be thermocompression bonded, and the electrodes can be directly connected to each other without the need to ultrasonically bond the terminals of the members to be bonded. Therefore, the manufacturing process is simple and the manufacturing cost is low.

  Further, when the substrates are bonded to each other, the tip width of the electrodes is as narrow as 100 μm or less, preferably 30 μm or less. Therefore, the required load to be applied is low, and electrical connection is possible with a low load, thus increasing the number of electrodes. Even in the case, it is possible to cope with commercially available equipment without installing a special pressurizing device.

  In the present invention, since the adhesive does not contain conductive particles, the insulation between the electrodes can be easily ensured, and even when the electrode pitch is narrowed, the reliability of the insulation between adjacent electrodes can be ensured. it can. Thereby, also in the present invention, since the mounting occupation area can be reduced, high-density mounting is possible. In addition, when the first and second substrates are separated, even if an insulating adhesive remains between the electrodes of each substrate, insulation between the electrodes is ensured, so only the adhesive on the electrodes is removed. The adhesive removal work at the time of repair is easy. In addition, since the electrical connection between the electrodes can be obtained without deforming the conductive layer of the wiring board (substrate), the wiring board is not limited to the material (hardness) of the wiring board, and the wiring boards can be arbitrarily combined. Electrical connection is possible.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a substrate electrode connection structure according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. In the present embodiment, the flexible wiring board 2 is connected to the rigid wiring board 1. As shown in FIG. 2, the rigid wiring board 1 has an external electrode 3 that is intentionally thin, and the flexible wiring board 2 has an external electrode 4 that is intentionally thin at a position matching the external electrode 3. Has been placed. As shown in FIG. 3, these electrodes 3 and 4 have an electrode tip width d of 100 μm or less, preferably 30 μm or less. The electrode tip surface is a flat surface. In addition, if the base end part width | variety of the electrodes 3 and 4 is smaller than the arrangement pitch of an electrode, it is arbitrary.

  Both the wiring boards 1 and 2 are provided between the electrodes 3 and 4 in a state where both the wiring boards 1 and 2 are arranged and the tip surfaces of the electrodes 3 and 4 are brought into contact with each other. Joined by an insulating adhesive 5. The insulating adhesive 5 is cured by pressurizing and heating after aligning the wiring boards 1 and 2, and bonds both the wiring boards 1 and 2.

  At this time, the external electrodes 3 and 4 are thinly formed so that the electrode tip width d is 100 μm or less, preferably 30 μm or less. Therefore, the contact area of the electrode tip surface is reduced, so that by applying a small load, It is possible to obtain a pressure necessary for conduction between the external electrodes 3 and 4. Thus, in the present invention, the tip width of the electrode can be made sufficiently small, so that electrical connection is possible with a low load. Therefore, even when the number of electrodes is increased, a special pressurizing device is used. Without installation, it can be handled by commercially available equipment.

  Therefore, according to the present embodiment, it is not necessary to use a conductive adhesive containing conductive particles, and it is possible to ensure electrical connection between the wiring boards without forming a tapered tip in advance. it can.

  In this embodiment as well, since the adhesive does not contain conductive particles, the insulation between the electrodes is easily ensured, and even when the electrode pitch is narrowed, the reliability of the insulation between adjacent electrodes is ensured. Can do. Thereby, also in the present invention, since the mounting occupation area can be reduced, high-density mounting is possible. In addition, during the repair work for separating the first and second substrates, even if the insulating adhesive remains between the electrodes of each substrate, the insulation between the electrodes is ensured, so only the adhesive on the electrodes What is necessary is just to remove and the adhesive removal work at the time of repair is easy. In addition, since the electrical connection between the electrodes can be obtained without deforming the conductive layer of the wiring board (substrate), it is not limited to the material (hardness) of the wiring board, and the wiring boards can be arbitrarily combined. Electrical connection is possible.

  Moreover, in this embodiment, although the rigid wiring board and the flexible wiring board were mentioned as an example, the rigid wiring boards, the flexible wiring boards, the combination of a glass substrate and a flexible wiring board, and a ceramic wiring board and a flexible wiring board, The present invention can be applied to various combinations such as combinations of

  Next, with reference to FIGS. 4A to 4D, the substrate electrode connecting method of this embodiment will be described.

  First, as shown in FIG. 4A, on the rigid wiring board 1 having the external electrode 3 formed to have a thin tip width of 100 μm or less, preferably 30 μm or less as shown in FIG. Adhesive adhesive 5 is supplied. Next, a flexible wiring board 2 is prepared in which the external electrode 4 is formed so that the tip width is 100 μm or less, preferably 30 μm or less, at a position aligned with the external electrode 3. Are arranged so that they face each other. Thereafter, as shown in FIG. 4D, after the wiring boards 1 and 2 are aligned so that the positions of the electrodes 3 and 4 are aligned, the insulating adhesive 5 is cured by pressing and heating. Then, the wiring boards 1 and 2 are joined together with the insulating adhesive 5.

  In this embodiment, the electrode tip width is narrowed so that the contact area between the external electrodes is reduced in the wiring board manufacturing process (circuit formation process), so that the electrodes 3 and 4 are electrically connected with a small load. Is possible. Therefore, according to the present embodiment, it is not necessary to use an adhesive containing conductive particles and a wiring board in which protrusions are formed in advance on the electrodes, so that the member cost can be reduced. Moreover, since the electrical connection with a low load can be realized by reducing the contact area between the external electrodes 3 and 4, even when the number of electrodes is increased, the wiring board can be connected with a commercially available facility. In addition, in the present embodiment, the tip surfaces of the electrodes 3 and 4 may be flat, and it is not necessary to form protrusions with tapered tips or bumps, so that the manufacturing process is simple and the manufacturing cost is low. .

  The insulating adhesive 5 may be in the form of a film or a paste. Further, it may be provided on either of the wiring boards 1 and 2.

  Next, another embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 5, in the present embodiment, only one of the external electrodes 4 of the wiring boards 1 and 2 is thinned, and the other external electrode 3 has a normal width.

  Thus, in the present embodiment, since the other external electrode 3 has a normal electrode width, even if the relative positions of the two wiring boards 1 and 2 are slightly deviated as shown in FIG. Reliability and insulation reliability with adjacent electrodes can be easily ensured.

  In each of the above embodiments, a thermoplastic insulating adhesive can be used as the insulating adhesive 5. As described above, by using the thermoplastic insulating adhesive, it becomes easy to remove the adhesive, so that a connection structure having excellent repairability can be obtained.

  The present invention can be used for electrode connection of various substrates such as conductive connection between a liquid crystal module and a rigid wiring board and conductive connection between a liquid crystal (glass) substrate and a flexible wiring board (production of a liquid crystal module).

It is a perspective view which shows the connection structure of the board | substrate (wiring board) electrode which concerns on embodiment of this invention. It is sectional drawing by the AA line of FIG. It is sectional drawing which shows the electrode width d of a wiring board. (A) thru | or (d) is sectional drawing which shows the connection method of the connection structure of the board | substrate electrode shown in FIG. 2 in order of a process. It is sectional drawing which shows the connection structure of the board | substrate electrode which concerns on other embodiment of this invention. It is sectional drawing which similarly shows a connection part when the relative position of the both wiring boards has shifted | deviated.

Explanation of symbols

1: Rigid wiring board 2: Flexible wiring board 3, 4: Electrode 5: Insulating adhesive

Claims (6)

The first and second substrates, each having an electrode having a tip width of 100 μm or less, are joined with an insulating adhesive provided between the electrodes of each substrate in a state where the tips of the electrodes are butted, A substrate electrode connection structure, wherein the electrodes of the first and second substrates are electrically connected to each other. 2. The substrate electrode connection structure according to claim 1, wherein a tip width of the electrode is 30 [mu] m or less. The substrate electrode connection structure according to claim 1, wherein a tip surface of the electrode is a flat surface. Forming a first electrode having a tip width of 100 μm or less on the surface of the first substrate, and providing an insulating adhesive on the surface of the first substrate so as to cover the first electrode; A step of forming a second electrode having a tip width of 100 μm or less on the surface of the second substrate, and the first and second substrates are arranged such that the tip surfaces of the first and second electrodes abut each other. And a step of joining the first and second substrates with the insulating adhesive. The method for connecting substrate electrodes according to claim 4, wherein a tip width of the electrode is 30 μm or less. 6. The method for connecting substrate electrodes according to claim 4, wherein the tip surface of the electrode is a flat surface.

Images