JPH08148213A - Connection member and structure and method for connecting electrode using the same - Google Patents

Abstract

PURPOSE: To provide a connection member with high resolution, reliability for a long period and excellent workability by causing the component of the binder of an electrically conductive adhesive layer and that of an insulating adhesive layer formed in one surface thereof to be adhesive materials of the same reaction. CONSTITUTION: An insulating adhesive layer 2 is formed at least in one surface of an electrically conductive adhesive layer 1 constituted of a binder 4 containing an electrically conductive material 3 having electric conductivity in a pressurizing direction. The layer 2 may be formed in both surfaces of the layer 1. For the binder 4 and the layer 2, adhesives of the same reaction, such as epoxy adhesives and the like, showing hardening when exposed to heat and lights are used. Thus, adhesive stress in a connection section is not diffused, reliability can be improved and manufacturing costs can be reduced.

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 electronic parts and circuit boards, or circuit boards to each other, and electrically connecting both electrodes, and an electrode connecting structure using the connecting members. And 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 which is excellent in workability because accurate alignment between conductive particles and an electrode is unnecessary, an electrode connecting structure using the connecting member, and a connecting method.

[0006]

According to the present invention, an insulating adhesive layer is formed on at least one surface of an adhesive layer having a conductive material containing a conductive particle having a uniform particle size and a binder, and having conductivity in the pressing direction. However, at least one of the insulating adhesive layer and the connecting member made of the same reactive adhesive having the same binder component and the electrode rows facing each other is projected, and the conductive material of the connecting member is placed between the electrodes facing each other. There is one or more and an insulating adhesive layer has a connection structure of electrodes in which at least the substrate side of the protruding electrodes covers at least the periphery of the protruding electrodes, and at least one of the electrodes has a protruding electrode, and the connecting member of the connecting member is provided between electrode rows facing each other The present invention relates to a method for connecting electrodes in which an insulating adhesive layer is arranged so as to be on the protruding electrode side and heated and pressed at a temperature equal to or higher than the activation temperature of the reactive adhesive.

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 FIG. 3E, 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. Among these, FIG. 3 (c) to (e)
As described above, the case where the conductive material 3 can be present in a single layer having almost the same thickness as the binder 4 is preferable because of the holding property of the conductive material 3 at the time of connection, and FIGS. 3D and 3E are particularly preferable. is there. The ratio of the conductive material 3 to the binder 4 is 0.1 to 3
About 0% by volume is preferable because conductivity anisotropy is easily obtained. Also,
In order to easily obtain conductivity in the thickness direction, the thickness of the binder 4 is preferably as thin as possible in the film formation range, and preferably 3
It is 0 μm or less, more preferably 20 μm or less.

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 upper limit of particle size is
Small particle size is suitable for securing a large number of particles of 1 or more, preferably 5 or more on a minute electrode.
Or less, more preferably 7 μm or less. The lower limit of the particle size should be 0.5 μm or more, preferably 1 μm or more in order to be able to deal with the cohesiveness of the particles and the unevenness of the electrodes.

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.

The conductive particles are preferably spherical particles having a uniform particle size with a small particle size distribution. If the particle size distribution is small,
Due to the pressure applied during electrode connection, it is held between the electrodes and little outflow occurs. The particle size distribution width is preferably within 1/2 of the maximum particle size in consideration of irregularities on the electrode surface. For example,
In the case of a deformable particle in which a polymer core material is coated with a conductive layer, there is a highly accurate particle having a center diameter of ± 0.2 μm or less, which is particularly preferably applicable. Further, in the case of hard metal particles, since they penetrate the electrode, the distribution width of the particle size may be relatively wide, within 1/2 of the maximum particle size. It is also possible to use insulating particles in combination with the conductive particles. When the insulating particles are used together, the insulating property with the adjacent electrode is improved and the gap between the connecting electrodes is adjusted. In the case of adjusting the gap, preferably, the insulating particles are made larger in diameter than the conductive particles to be harder than the conductive particles, and good results can be expected.

The insulating particles include inorganic substances such as glass, silica and ceramics, and organic substances such as polystyrene, epoxy and benzoguanamine, and their shape may be spherical, fibrous or the like. These can be used alone or in combination. The binder and insulating adhesive layer are reactive adhesives, and materials that are curable by heat or light can be widely applied.
It is preferable to have 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 a main component, curing agents, catalysts,
It is common to add a coupling agent, a filler and the like.

The curing agent in the present invention is preferably latent in order to maintain the storability 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.

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 them can be adopted. An electrode connection structure using the connection member of the present invention and a manufacturing method thereof will be described with reference to FIGS. FIG. 4 shows a structure in which the protruding electrode 12 formed on the substrate 11 and the planar electrode 13 of the substrate 11 'are connected via the connecting member of the present invention. That is, at least one of the electrode rows facing each other has a connecting structure between the protruding electrode rows, and the connecting structure between the electrode rows facing each other is 12-1.
One or more conductive materials 3 exist between the three electrodes 3, and the protruding electrode 1
The conductive material exists in a state in which the density of the conductive material is higher than that of the periphery 14 of the electrode 2, and the electrode rows facing each other are connected to each other. The insulating adhesive layer 2 covers at least the periphery of the protruding electrode 12 on the substrate side of the protruding electrode.

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 substrates 11 and 1.
This is a case where the electrodes formed in 5 are the protruding electrodes 12 and 12 '. That is, it is a structure in which the both surfaces shown in FIG. 2 are connected via the connecting member having the 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, and are also connected to the respective substrate surfaces 11 and 15.

As the substrate in FIGS. 4 and 5, plastic films such as polyimide and polyester, composites such as glass epoxy, semiconductors such as silicone, glass,
Examples include inorganic materials such as ceramics. Protruding electrode 1
2 can 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 connecting member is arranged so that the insulating adhesive layer 2 of the connecting member is on the protruding electrode 12 side, and is heated and pressed at a temperature equal to or higher than the activation temperature of the reactive adhesive. .

[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 Conductive particles were removed from the conductive adhesive layer in (1) to obtain a thickness of 15
An insulating adhesive layer was prepared from the μm sheet in the same manner as in (1) above. The surface of the conductive adhesive layer (1) and the surface of the adhesive layer (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, bubbles were not mixed and the particles were spherical, but at least 50 particles were present on the electrodes and compression molded, and the particles were 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, which were almost 85 ° C. and 85% RH even after 1000 hours of treatment. It showed no change and showed good long-term reliability. In this embodiment,
Since the adhesive strength of the flat electrode on the glass side was relatively lower than that on the FPC side, when it 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.
The number of particles on the electrode was at least 35. Example 3 The conductive particles in the conductive adhesive layer of Example 2 were replaced. That is, Ni particles (maximum diameter 5 μm, minimum diameter 2.5 μm) were made, and 1 volume% was added. In this case as well, the result of evaluation as in Example 2 showed good connection characteristics. When the connection portion was peeled off and observed with an electron microscope, 20 or more conductive particles were present on one electrode, and it could be observed that the conductive surface was stuck into the electrode surface.

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. The conductive material of the conductive sheet is conductive particles having a particle size of 3 ± 0.1 μm, the addition amount is 1% by volume, and the thickness of the matrix is 10
The sheet has a thickness of μm, and has a configuration corresponding to FIG. 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. There was no air bubble mixing between adjacent bumps, showing 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. There were 5 or more conductive particles on one electrode.

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. There were 10 or more conductive particles on one electrode.

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 size of 5 μm was coated with a nylon resin having a glass transition point of 127 ° C. to a thickness of about 0.2 μm, and the addition amount 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, and there were 60 or more particles. The electrode connecting portion 12-12 'is
It is possible to conduct electricity 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 remains covered with the insulating layer 2, so that insulation is achieved. The property was also good. In this configuration, the conductive material 3
The density with respect to the binder 4 can be made high.

Example 7 Similar to the connecting member of Example 1, except that benzoguanamine particles having a particle diameter of 2 ± 0.1 μm were added in addition to the conductive particles. When evaluated in the same manner as in Example 1, good connection characteristics were shown. When the cross section of this connection body was polished and observed under a microscope, the connection structure was equivalent to that shown in FIG. In this embodiment,
By using the insulating particles 5 in combination with the conductive material 3 (conductive particles), the insulating particles 5 having a hard gap between the connection electrodes.
The particle size of the (benzoguanamine particles) was controlled to 2 μm, and the conductive material 3 was deformed and was in surface contact with the electrodes 12 and 13.

[0025]

In the connecting member of the present invention, since the binder component and the insulating adhesive layer are the same reactive adhesive,
The adhesive stress in the connection portion does not have a distribution, the reliability is improved, the material preparation is easy, and the manufacturing cost is reduced.
In addition, since the conductive material contains conductive particles having a uniform particle size, even though the binder component and the insulating adhesive layer are the same component, the viscosity of the adhesive decreases due to heat and pressure during electrode connection. Also in the case of, the conductive particles are held between the electrodes,
Little outflow and can be retained on the electrode. In addition, the electrode connection structure of the present invention is a structure in which one or more conductive materials exist between electrodes facing each other, and the insulating adhesive layer covers at least the periphery of the protruding electrode on the substrate side. In connecting the electrodes, good conductivity in the thickness direction and good insulation in the plane direction are obtained together.

Further, the electrode connecting method of the present invention is a method of arranging the connecting member so that the insulating adhesive layer of the connecting member is on the protruding electrode side, and heating and pressurizing at a temperature higher than the activation temperature of the reactive adhesive. As a result, reliable surface direction insulation and strong mechanical connection can be obtained. Since the adhesive layer can be combined according to its purpose, for example, a material suitable for 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 part. 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.

FIG. 6 is a schematic sectional view showing an electrode connection structure using the connection member of the present invention.

[Explanation of symbols]

1 ... Conductive adhesive layer, 2 ... Insulating adhesive layer, 3 ... Conductive material,
4 ... Binder, 5 ... Insulating particles, 11, 11 '... Substrate, 1
2 ... Protruding electrodes, 13 ... Planar electrodes, 14 ... Surroundings, 15, 1
6 ... 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 containing a conductive particle having a uniform particle size and a binder and has conductivity in the pressing direction. And a connecting member made of a reactive adhesive having the same binder component. 2. The connecting member according to claim 1, wherein the adhesive layer having conductivity is made of a conductive material and insulating particles. 3. At least one of the electrode rows facing each other protrudes, one or more conductive materials of the connecting member according to claim 1 or 2 exist between the electrodes facing each other, and the insulating adhesive layer has a protruding electrode. Connection structure of electrodes covering at least the periphery of the substrate. 4. At least one has a protruding electrode,
It is arranged that the insulating adhesive layer 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 heating and pressurization is performed at a temperature equal to or higher than the activation temperature of the reactive adhesive. Characteristic electrode connection method.