JPH08148212A - Connection member and structure and method for connecting electrode using the same - Google Patents

Abstract

PURPOSE: To make an electrically conductive material difficult to mix with an insulating material and to eliminate accurate aligning of the positions of an electrically conductive particle and an electrode so as to improve workability by providing a difference in reaction between the binder component of an electrically conductive adhesive layer and an insulate adhesive layer. CONSTITUTION: A difference is provided in reaction between the binder component 4 of an electrically conductive adhesive layer 1 constituted of an electrically conductive material 3 and a binder and an insulate adhesive layer 2. A temperature for activating the component 4 is set low and its hardening speed is set faster than the layer 2. Thus, the material 3 is first brought into contact with an electrode because of pressure application and heating during connecting of the electrode, starting the hardening reaction of the component 4 and then, because of an increase in adhesiveness following the advance of the hardening reaction, the material 3 is fixed by the component 4. Subsequently, the layer 2 charges adjacent electrodes 12-12' and following the advance of the hardening reaction, this adheres and fixes both base boards. The same results when a temperature for activating the component 4 is set high and its shardening speed is se slow compared with that of the layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting member for bonding and fixing an electronic component and a circuit board, or circuit boards to each other, and electrically connecting both electrodes, and an electrode connecting structure using the connecting member.・ About connection method.

[0002]

2. Description of the Related Art In recent years, as electronic parts have become smaller and thinner, circuits used therein have become higher in density and higher in definition. Such electronic parts and fine electrodes can be connected by conventional solder or rubber connectors. Since it is difficult to cope with such problems, recently, anisotropic conductive adhesives and film materials (hereinafter,
Connection member) is often used. This connecting member is made of an adhesive containing a conductive material such as conductive particles in a predetermined amount, and the connecting member is provided between the electronic component and the electrode or circuit, and by applying pressure or heating / pressurizing means. The electrodes are electrically connected to each other, and the electrodes formed adjacent to the electrodes are provided with an insulating property so that the electronic component and the circuit are bonded and fixed. The basic idea for increasing the resolution of the above-mentioned connecting member is to make the particle size of the conductive particles smaller than the insulating portion between the adjacent electrodes to ensure the insulating property between the adjacent electrodes, and also to improve the conductive particles. The content of is set to such a degree that the particles do not come into contact with each other, and the particles are surely present on the electrode to obtain conductivity in the connection portion.

[0003]

The above-mentioned conventional method is
If the particle size of the conductive particles is reduced, the particles will undergo secondary aggregation due to the marked increase in the surface area of the particles, and the particles will be connected, making it impossible to maintain the insulation between adjacent electrodes.If the content of the conductive particles is reduced, the particles will be connected. Since the number of conductive particles on the power electrode also decreases, the number of contact points becomes insufficient, and conduction between the connection electrodes cannot be obtained, so it is difficult to improve the resolution of the connection member while maintaining long-term connection reliability. there were. That is, due to the recent remarkable high resolution, that is, the miniaturization of the electrode area and the space between adjacent electrodes (space), the conductive particles on the electrodes flow out between the adjacent electrodes together with the adhesive due to the pressure at the time of connection or the heat and pressure. This has been an obstacle to increasing the resolution of the members.

At this time, if the adhesive has a high viscosity in order to suppress the outflow of the adhesive, the contact between the electrodes and the conductive particles becomes insufficient, making it impossible to connect the electrodes facing each other. On the other hand, when the adhesive has a low viscosity, in addition to the outflow of the conductive particles, bubbles are likely to be included in the space portion, and the connection reliability, particularly the moisture resistance is deteriorated. From this, a conductive particle-containing layer and an insulating adhesive layer are separated into a multi-layered connecting member, and the viscosity at the time of connection is high.
Attempts have been made to retain the conductive particles, but they have not been put into practical use because the contact between the electrodes and the conductive particles is insufficient or the manufacturing method is troublesome.

Further, as a connection member which enables connection of such fine electrodes and circuits and is excellent in connection reliability, there is also a proposal of a connection member having a dense region of conductive particles in a necessary portion in the plane direction. According to this, although it is possible to connect a dot-shaped fine electrode such as a semiconductor chip, there is a drawback that workability is inferior because accurate alignment of the dense region of conductive particles and the dot-shaped electrode is required. The present invention has been made in order to eliminate the above drawbacks, it is possible to hold a small outflow of conductive particles from the electrode, and also excellent long-term connection reliability because it is difficult to contain bubbles in the connection portion, (EN) Provided are a high-resolution connecting member excellent in workability because accurate alignment between conductive particles and an electrode is unnecessary, and an electrode connecting structure and connecting method using the connecting member.

[0006]

According to the present invention, an insulating adhesive layer is formed on at least one side of an adhesive layer which is made of a conductive material and a binder and has conductivity in the pressing direction. A connecting member having a difference in reactivity with the component of the binder, at least one of the opposing electrode rows is projected, the conductive material of the connecting member is present between the opposing electrodes, and the insulating adhesive layer is An electrode connection structure covering at least the substrate side of the projecting electrode, and at least one projecting electrode so that the insulating adhesive layer of the connecting member is on the projecting electrode side between the electrode rows facing each other. The present invention relates to a method for connecting electrodes, which are arranged at a temperature higher than the activation temperature of the insulating adhesive layer and the binder component on the high temperature side or higher.

The present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a connecting member for explaining an embodiment of the present invention. The connecting member of the present invention is a multilayer connecting member made of a conductive material and a binder and having an insulating adhesive layer 2 formed on at least one surface of a conductive adhesive layer 1 having conductivity in the pressing direction. As shown in FIG. 2, insulating adhesive layers 2 and 2 ′ may be formed on both surfaces of the conductive adhesive layer 1. A peelable separator (not shown) may be present on these surfaces, if necessary, in order to prevent unnecessary adhesion and adhesion of dust and the like. FIG. 3 is a schematic cross-sectional view illustrating the conductive adhesive layer 1 having conductivity in the pressing direction. The conductive adhesive layer 1 is
It is composed of a binder 4 containing a conductive material 3. Here, as the conductive material 3, as shown in FIGS. 3A to 3D, the thickness of the binder 4 is reduced by applying pressure or heating / pressurizing means to obtain conductivity, that is, the thickness of the binder 4 or less. Those having a small particle size are preferred. Further, as shown in FIGS. 3E to 3G, the binder 4 may be projected from the front and back surfaces (not shown but only one may be provided).

When the conductive material 3 is less than the thickness of the binder 4, the binder 4 holds the conductive material 3, so that the conductive material 3 can be prevented from falling off during handling. If the conductive material 3 projects from the surface of the binder 4, the electrode can be easily contacted. Can be conducted with
Easy to obtain conductivity. The ratio of the conductive material 3 to the binder 4 is preferably about 0.1 to 30% by volume because conductivity anisotropy is easily obtained. Further, in order to easily obtain conductivity in the thickness direction, it is preferable that the thickness of the binder 4 is as thin as possible in the film formation range.
It is preferably 30 μm or less, more preferably 20 μm or less. As the conductive material 3, for example, FIG.
It is preferable to form the conductive particles as illustrated in (e) because the production is easy and the availability is easy. Further, the conductive material 3 is provided with a through hole in the binder 4 as shown in FIG.
A conductor may be formed by plating or the like, or a conductive fiber such as a wire may be formed as shown in FIG.

As the conductive particles, Au, Ag, Pt, N
There are metal particles such as i, Cu, W, Sb, Sn and solder, carbon powder, etc., and these conductive particles are used as a core material, or polymers such as non-conductive glass, ceramics or plastics. It is also possible to cover the core material made of (1) with a conductive layer made of the above material. Further, insulating coated particles obtained by coating a conductive material with an insulating layer, and combined use of conductive particles and insulating particles are also applicable. The particle diameter is preferably 15 μm or less, more preferably 7 μm or less, in order to secure one or more particles, preferably a large number of particles, on a fine electrode.

Among these conductive particles, those in which a conductive layer is formed on a hot-melt metal such as solder or a polymer core material such as plastic have heat pressurization or deformability due to pressurization and form a circuit when laminated. The contact area is increased and the reliability is improved, which is preferable. In particular, when polymers are used as the core, they do not exhibit a melting point like solder, so the softened state can be widely controlled at the connection temperature, and it is possible to obtain a connection member that can easily cope with variations in electrode thickness and flatness. preferable. Also, for example, Ni, W
In the case of hard metal particles such as or particles having a large number of protrusions on the surface, since the conductive particles pierce the electrode or wiring pattern,
Even if an oxide film or a contaminated layer is present, low connection resistance can be obtained, and reliability is improved, which is preferable.

As the binder 4, a material which is curable by heat or light can be widely applied and preferably has adhesiveness.
Since these have excellent heat resistance and moisture resistance after connection, application of a curable material is preferable. Among them, the epoxy adhesive is preferably applicable because it can be cured in a short time, has good workability in connection, and has excellent adhesiveness due to its molecular structure. Epoxy adhesives include, for example, high molecular weight epoxies, solid epoxies and liquid epoxies, epoxies modified with urethane, polyester, acrylic rubber, NBR, nylon, etc. as main components, and curing agents, catalysts, coupling agents, fillers, etc. Is generally added.

The present invention is characterized by providing a difference in reactivity between the binder component 4 and the insulating adhesive layer 2. As a preferred embodiment thereof, the activation temperature of the binder component 4 is set to a low temperature, that is, the curing speed is set faster than that of the insulating adhesive layer 2. Alternatively, the activation temperature of the binder component 4 is set to a high temperature, and the curing speed is set to be slower than that of the insulating adhesive layer 2. The activation temperature of the binder component 4 is set to a low temperature,
By making the curing faster than that of the insulating adhesive layer 2, the conductive material 3 first comes into contact with the electrode by heating and pressurizing at the time of electrode connection, the curing reaction of the binder 4 is started, and then the viscosity increases with the progress of the curing reaction. Thus, the conductive material 3 is fixed by the binder component 4. Subsequently, the insulating adhesive layer 2 is formed between the adjacent electrodes 12-1.
2'is filled, and both substrates are bonded and fixed as the curing reaction proceeds. In the latter case, since the insulating adhesive layer 2 forms the cured film first, bubbles are less likely to be generated, and the conductive material 3 is fixed by the binder component 4 so that both layers can be formed separately.

As a method of providing a difference in reactivity between the binder component 4 and the insulating adhesive layer 2, the kind and amount of curing agent,
It is common to select particle size and the like. The curing agent is preferably latent in order to maintain the storage stability of the connecting member. The term “latent” as used in the present invention means that it has a storage stability at 30 ° C. or lower for 2 months or more in the coexistence with a reactive resin (for example, an epoxy resin), and rapidly cures under heating. Further, the reactivity of the present invention refers to the activation temperature in the coexistence of the reactive resin and the latent curing agent. The activation temperature was 3 mg of the coexisting mixed sample of the reactive resin and the latent curing agent, and the DSC (Diff
erial scanning calorimeter (pointing scanning calorimeter) is used and the peak temperature showing the maximum calorific value when the temperature is raised from normal temperature (30 ° C) to 250 ° C at 10 ° C / min.

The difference in activation temperature between the conductive adhesive layer 1 and the insulating adhesive layer 2 is possible if it is set to 1 ° C. or more, and should be 50 ° C. or less in consideration of workability at the time of connection. . To clarify the difference in reactivity and enable connection, 1 ° C. or higher is required, and the preferable difference in activation temperature is 5 ° C. or higher, more preferably 10 ° C. or higher. Further, the reason why the upper limit of the activation temperature difference is set to 50 ° C. or less is that it takes a longer time to complete the curing of both layers at the time of connection as the temperature difference increases, which is not practical, and preferably 45 ° C. or less. , More preferably 40 ° C
The following makes the implementation of the present invention more reliable. As the method for producing the connecting member of the present invention, for example, a method of laminating the conductive adhesive layer 1 and the insulating adhesive layer 2 or a method of sequentially laminating and coating the layers can be adopted. 4 to 5 show an electrode connection structure using the connection member of the present invention and a manufacturing method thereof.
This will be described below.

FIG. 4 shows the protruding electrode 1 formed on the substrate 11.
2 shows a structure in which 2 and the planar electrode 13 of the substrate 11 'are connected via the connecting member of the present invention. That is, in the connection structure between the electrode rows in which at least one of the electrode rows facing each other protrudes, the conductive material 3 exists between the electrodes 12-13 of the electrode tips facing each other, and Also conductive material 3
Exist in a high density state, and the electrode rows facing each other are connected. Moreover, the insulating adhesive layer 2 covers at least the periphery of the protruding electrode of the protruding electrode 12. Here, the flat electrode 13 has no unevenness from the surface of the substrate 11 ′, or even if there is unevenness, it is a few μm or less. To exemplify these, the electrodes obtained by the additive method or the thin film method are typical.

FIG. 5 shows the case where the electrodes formed on the substrates 11 and 15 are the protruding electrodes 12 and 12 '. That is,
This is a structure in which both surfaces shown in FIG. 2 are connected via a connecting member having insulating adhesive layers 2 and 2 '. The insulative adhesive layers 2 and 2'cover the surroundings of the protruding electrodes of the protruding electrodes 12 and 12 ', respectively.
1 and 15 are connected. Examples of the substrate in FIGS. 4 and 5 are plastic films such as polyimide and polyester, composites such as glass epoxy, semiconductors such as silicone, and inorganic substances such as glass and ceramics. The protruding electrode may include various circuits and terminals in addition to the above. The various electrodes shown in FIGS. 4 and 5 can be applied in any combination. In the electrode connecting method using the connecting member of the present invention, the insulating adhesive layer 2 of the connecting member is arranged so as to be on the side of the protruding electrode, and heated and pressed at a temperature equal to or higher than the activation temperature of the conductive adhesive layer 1. .

[0017]

EXAMPLES Next, examples will be described, but the present invention is not limited to these examples. Example 1 (1) Preparation of Conductive Adhesive Layer The ratio of a phenoxy resin (polymer epoxy resin) as a film forming material to a liquid epoxy resin containing a microcapsule type latent curing agent (epoxy equivalent 185) was 20.
/ 80 to obtain a 30% solution of ethyl acetate. In this solution, Ni / A was added to polystyrene particles having a particle size of 5 ± 0.2 μm.
5% by volume of electroconductive particles having a metal coating of 0.2 / 0.02 μm in thickness of u were added and mixed and dispersed. This dispersion was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 110 ° C. for 20 minutes to obtain a conductive adhesive layer having a thickness 5 μm. The activation temperature of this adhesive layer was 108 ° C.

(2) Formation of Insulating Adhesive Layer and Preparation of Connection Member The conductive particles are removed from the conductive adhesive layer of (1) to increase the coating thickness of the microcapsule type latent curing agent and to activate it. Was set to 119 ° C. and a sheet having a thickness of 15 μm was prepared as in (1) above to form an insulating adhesive layer. First, (1)
The surface of the conductive adhesive layer of (1) and the surface of the adhesive layer of (2) were laminated while being rolled between rubber rolls. As described above, the multilayer connecting member having the two-layer structure shown in FIG. 1 was obtained. (3) Connection A two-layer FPC circuit board (circuit pitch 100 μm, parallel circuit electrodes with electrode width 50 μm) having a copper circuit 18 μm high on a polyimide film, and 1.1 mm thick on glass Connection was made with a flat electrode having a 0.2 μm (ITO, surface resistance 20 Ω / □) indium oxide thin film circuit. First, the conductive adhesive layer was placed on the flat electrode side. The connecting member was placed with a width of 1.5 mm, and the separator was peeled off and then attached. After this, peel off the separator,
Align the upper and lower circuits with other circuit boards,
The connection was made for 15 seconds at kgf / mm ² .

(4) Evaluation When a cross section of this connector was polished and observed with a microscope,
The connection structure was equivalent to that in FIG. In the space between the adjacent electrodes, particles were spherical without inclusion of bubbles, but the particles were compression-molded on the electrodes and held in contact with the upper and lower electrodes. As a result of evaluating the connection resistance between the electrodes facing each other and the insulation resistance between the adjacent electrodes, the connection resistance was 1 Ω or less and the insulation resistance was 10 ⁸ Ω or more, and these were 85 ° C. and 85% RH10.
After the treatment for 00 hours, there was almost no change and good long-term reliability was shown. In this example, since the adhesive force of the flat electrode on the glass side was relatively lower than that on the FPC side, when the film was forcibly peeled from the glass side, the interface was peeled off neatly and the subsequent cleaning was easy. . This is suitable for imparting repairability to the connection of liquid crystal panels that are often used in the same configuration at present.

Example 2 An insulating adhesive layer was further formed on the conductive adhesive layer of Example 1 to obtain a multi-layer connection member having a three-layer structure shown in FIG. The FPCs of Example 1 were similarly connected. In this case, the connection body shown in FIG. 5 was obtained and showed good connection characteristics as in Example 1. Example 3 The curing agents of the conductive adhesive layer and the insulating adhesive layer of Example 1 were replaced. That is, the activation temperature of the binder component was set to a high temperature, and the curing speed was set to be slower than that of the insulating adhesive layer.
Also in this case, as a result of evaluation in the same manner as in Example 1, since the insulating adhesive layer formed the cured film first, the conductive material was also fixed with the binder component, and both layers could be formed separately.

Example 4 The same as Example 1, except that instead of the FPC, there were 200 IC chips (2 × 10 mm, height 0.5 mm, 50 μm squares called bumps around the four sides, and 20 μm height gold electrodes). Formation) was used. The ITO electrode on the glass side was changed to correspond to the size of the bump electrode of the IC chip. In addition, the conductive material of the conductive sheet is conductive particles having an average particle size of 3 μm, the addition amount is 1% by volume, and the thickness of the matrix is 10 μm.
The sheet has a structure corresponding to that of FIGS.
The connection body had a structure corresponding to that shown in FIG. 4, but showed good connection characteristics. In this example, the bump was mushroom-shaped and had a top portion, but the particles were compressed and deformed and held in contact with the upper and lower electrodes. No bubbles are mixed between adjacent bumps,
It showed good long-term reliability. The degree of deformation of the conductive particles was different depending on the relative distance between the electrodes, and some of the conductive particles also partially penetrated into the bumps.

Example 5 The same as the connecting member of Example 2, except that the insulating adhesive layer was formed to have a thickness of 25 μm on one side and 50 μm on the other side. The electrodes are QFP type IC leads (thickness 100 μm, pitch 3
00 μm) and was connected to a terminal of copper having a thickness of 35 μm on the glass glass epoxy substrate. This configuration is equivalent to FIG. 5, but has no substrate on one side. In this example, electrodes having large heights were connected to each other, but there was no electrode displacement and good connection characteristics were exhibited. Although the conductive material in the conductive sheet is not shown, the particles were compressed and deformed and held in contact with the upper and lower electrodes. There were no bubbles mixed between adjacent electrodes, and good long-term reliability was shown. In this example, the adhesive layer was formed along the lead height even in the portion without the substrate, and the lead could be fixed.

Example 6 Similar to the connecting member of Example 1, the surface of the conductive particles was subjected to an insulating coating treatment. That is, the surface of conductive particles having an average particle diameter of 3 μm was coated with nylon resin having a glass transition point of 127 ° C. to a thickness of about 0.2 μm, and the amount of addition was increased to 10% by volume. The same evaluation as in Example 3 was performed, but good connection characteristics were shown. In this example, the number of particles on the electrode 12 increased remarkably. The electrode connecting portions 12-12 'can be conducted by softening the insulating layer 2 and the binder 4 due to the heat pressure at the time of connection, but the space portion of the adjacent electrode row has a small heat pressure and the surface of the conductive material 3 has the insulating layer 2 Since it was still covered with, the insulating property was also good. In this configuration, the concentration of the conductive material 3 with respect to the binder 4 can be set to be high.

[0024]

Since the connecting member of the present invention has a difference in reactivity between the binder component of the conductive adhesive layer and the insulating adhesive layer, the conductive material is hard to mix with the insulating adhesive layer, and the conductive material is not easily mixed with the conductive adhesive layer. There is little outflow. Since the conductive material of the conductive adhesive layer is uniformly dispersed on the entire surface, it is not necessary to accurately align the conductive particles and the electrodes, and therefore workability is excellent. Therefore, the resolution is high and the connection reliability is excellent. The electrode connection structure of the present invention is a structure in which the conductive material is present between the electrodes facing each other, and the insulating adhesive layer covers at least the substrate side periphery of the protruding electrode, so in the connection of the fine electrodes, Good conductivity in the thickness direction and good insulation in the plane direction are obtained together. The electrode connecting method of the present invention is arranged such that the insulating adhesive layer of the connecting member is on the protruding electrode side, and is heated and pressed at a temperature equal to or higher than the activation temperature on the high temperature side of the binder component and the insulating adhesive. Since this method is used, reliable in-plane insulation and strong mechanical connection can be obtained.

Since the adhesive layer can be combined according to the purpose, for example, in accordance with the material of the electrode substrate, the choice of materials is expanded, and the connection reliability is also improved due to the reduction of bubbles in the connection portion. Further, by making one of them soluble or swellable in a solvent, or by giving a difference in heat resistance, it is possible to preferentially separate from one substrate surface, and to provide so-called repairability for reconnection. . Alternatively, any combination suitable for the material of the electrode substrate can be used, the contact between the electrode and the conductive particles can be easily obtained, and the manufacturing method is also simple. In addition, the adhesive layer can be made to stick out of the connection portion to obtain a reinforcing effect and a moistureproof effect by the action of a sealing material.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a connecting member of the present invention.

FIG. 2 is a schematic sectional view of a connecting member of the present invention.

FIG. 3 is a schematic sectional view showing a conductive adhesive layer in the connecting member of the present invention.

FIG. 4 is a schematic cross-sectional view showing an electrode connection structure using the connection member of the present invention.

FIG. 5 is a schematic cross-sectional view showing a connection structure of electrodes using the connection member of the present invention.

[Explanation of symbols]

1 ... Conductive adhesive layer, 2 ... Insulating adhesive layer, 3 ... Conductive material,
4 ... Binder, 11 ... Substrate, 11 '... Substrate, 12 ... Projected electrode, 13 ... Planar electrode, 14 ... Surrounding, 15 ... Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Nakajima 1150 Gozamiya, Shimodate City, Ibaraki Prefecture Inside the Yuki Plant of Hitachi Chemical Co., Ltd. (72) Inventor Hiroshi Matsuoka 1150 Gogomiya, Shimodate City, Ibaraki Hitachi Seiko Co., Ltd. Yuki factory

Claims (4)

[Claims] 1. An insulative adhesive layer is formed on at least one surface of an adhesive layer which is made of a conductive material and a binder and has conductivity in the pressing direction, and the reactivity between the insulative adhesive layer and the components of the binder. Connection member with a difference. 2. The activation temperature shown by the DSC peak temperature is between 1 and 50 between the insulating adhesive layer and the binder component.
The connection member according to claim 1, wherein a difference of ° C is provided. 3. At least one of the electrode rows facing each other is projected, the conductive material of the connecting member according to claim 1 is present between the electrodes facing each other, and the insulating adhesive layer is at least the substrate of the projecting electrodes. The connection structure of the electrode that covers the periphery of the side. 4. At least one has a protruding electrode,
The insulating member of the connecting member according to claim 1 or 2 is arranged between the opposing electrode rows so that the insulating adhesive layer is on the protruding electrode side, and the insulating adhesive layer and the binder component have a temperature higher than the activation temperature on the high temperature side. A method of connecting electrodes, which comprises heating and pressurizing at a temperature.