JP2008124029A - Connecting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting member for bonding and connecting circuit boards to each other, and electrically connecting electrodes of both the circuit boards. <P>SOLUTION: In the connecting member for connecting the electrodes opposed to each other, a conductive bonding layer made of a conductive material and a binder and having a conductivity in the pressure direction, and an insulating bonding layer are alternately formed, the conductive bonding layer and the insulating bonding layer are formed in cross-section when cut vertically with respect to the length direction of the tape, the insulating bonding layer is further formed on one or both faces of the conductive bonding layer and the insulating bonding layer arranged alternately, along the direction of the conductive bonding layer and insulating bonding layer arranged alternately. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component and a circuit board, and a continuous tape-like connecting member that bonds and fixes circuit boards and electrically connects both electrodes.

In recent years, with the miniaturization and thinning of electronic components, circuits used for these have become denser and higher definition. Since it is difficult to connect such an electronic component and a fine electrode with a conventional solder or rubber connector, an anisotropic conductive adhesive or a film-like material (hereinafter referred to as a connecting member) having excellent resolution is recently available. ) Is frequently used.
This connecting member is made of an adhesive containing a predetermined amount of a conductive material such as conductive particles, and this connecting member is provided between the electronic component and the electrode or circuit to form a pressurizing or heating / pressing means. As a result, the electrodes are electrically connected to each other, and the electrodes formed adjacent to the electrodes are provided with insulating properties so that the electronic component and the circuit are bonded and fixed.

The mounting using these connection members has been put into practical use for mounting a TAB mounted with an IC chip on a substrate such as glass or plastic, or mounting a bare chip directly on these substrates.
The basic idea for increasing the resolution of the connecting member is to ensure the insulation between the adjacent electrodes by making the particle size of the conductive particles smaller than the insulating portion between the adjacent electrodes. The content is set to such an extent that the particles do not contact with each other and is surely present on the electrode to obtain conductivity at the connection portion.

As a development of these ideas, recently, by forming a conductive layer and an insulating adhesive layer made of a conductive material and a binder in the pressurizing direction separately in the thickness direction to form a multilayer structure, Proposals have been made to separate the functions of conductivity in the thickness direction and insulation in the surface direction, and to cover the surface of the conductive particles with an insulating material, destroying the insulating material on the contact surface with the electrode during connection and increasing the resolution. It has been broken.
Furthermore, as a connecting member that enables connection of such fine electrodes and circuits and has excellent connection reliability, conductive particles and their dense regions or conductive materials are formed on necessary portions in the surface direction according to the arrangement of the electrodes and circuits. There is also a proposal of a connection member having a protrusion.

Although the above-mentioned conventional method enables connection of fine electrodes in both the case of a multi-layer structure and the case where the surface of conductive particles is covered with an insulating material, the number of necessary conductive particles on a large number of fine electrodes can be ensured. In order to ensure, the addition amount is great, and the cost increase of the connecting member is an important problem. The reason for this is that noble metals such as gold, which are the raw materials for the conductive material, are expensive, conductive particles having a uniform diameter are used in order to improve connection reliability, or unnecessary parts are also used. It can be pointed out that a large amount of conductive particles are present. In particular, when the surface of the conductive particles is covered with an insulating material, the conductive particles are present in a high density throughout the entire layer. is there.

  In the case of a connection member having a conductive material in a necessary part in the surface direction according to the arrangement of electrodes and circuits, it is possible to connect a dot-shaped fine electrode like a semiconductor chip, but a dense region of conductive particles and a dot shape Accurate alignment with the electrode is necessary, and there is a disadvantage that the connection workability is inferior.

  The present invention has been made in view of the above-mentioned drawbacks, and is a connection member that suppresses the amount of expensive conductive particles used, can secure an effective bonding area, and does not require accurate alignment with the dot-shaped electrode portion. The present invention also relates to a connection structure for electronic components using the same.

  According to the present invention, in a connection member for connecting electrodes facing each other, a conductive adhesive layer having conductivity in a pressing direction composed of a conductive material and a binder and an insulating adhesive layer are alternately formed. In addition, the conductive adhesive layer and the insulating adhesive layer are alternately formed in a cross section when cut perpendicular to the length direction of the tape, and the conductive adhesive layer and the insulating adhesive layer are alternately formed. A connection member in which an insulating adhesive layer is further formed on one or both sides along the formed direction, and as an embodiment, the area of the conductive adhesive layer is formed larger than the electrode area to be connected A connecting member, more preferably a continuous tape-like connecting member in which a conductive adhesive layer is continuously formed in the length direction of the tape, and a portion having a high conductive particle density using the continuous tape-like connecting member; Low On connecting structure of an electronic component in which the part becomes present.

As described above in detail, according to the present invention, since the conductive adhesive layer 1 is formed only in the necessary portion, the amount of expensive conductive particles used is reduced, and valuable precious metal resources are effectively utilized. it can. In addition, an effective bonding area can be ensured, and the bonding strength and reliability of the connected product are improved. In addition, alignment with the electrode part is easy.
Therefore, it is possible to provide a continuous tape-like connecting member having high resolution and excellent connection reliability and an electronic component connecting structure using the same.

The present invention will be described with reference to the drawings.
1 to 4 are schematic cross-sectional views of a continuous tape-like connecting member for explaining an embodiment of the present invention. As shown in FIG. 1, the continuous tape-like connecting member of the present invention is a separator in which a conductive adhesive layer 1 having conductivity in a pressurizing direction composed of a conductive material 3 and a binder 4 and an insulating adhesive layer 2 can be peeled off. 5 is a continuous tape-like connecting member formed alternately on the substrate 5. In addition, as shown in FIG. 2, the conductive adhesive layers 1 may be alternately formed on the main part of the insulating adhesive layer 2.
Further, as shown in FIG. 3, even if an insulating adhesive layer 2 ′ is further present on the surface of the configuration shown in FIG. 2, or the conductive adhesive layer 1 is formed only on the main part of the insulating adhesive layer 2 as shown in FIG. The conductive adhesive layer 1 may be formed in a symmetrical position (1-1 ′) on both sides of the insulating adhesive layer 2 with the insulating adhesive layer 2 interposed therebetween.
1 to 4, separators (FIGS. 2 to 4 are not shown) can be present as necessary. Moreover, since this continuous tape-shaped connection member is a continuous tape shape, continuous automation of a connection work process can be achieved. In this case, it is possible to form a narrow tape by arbitrarily slitting a plurality of windings formed alternately in the width direction.

  FIG. 5 is a plan view of a continuous tape-like connecting member for explaining another embodiment of the present invention. The conductive adhesive layer 1 may be at the end in the length direction of the tape as shown in FIG. 5A or at a position slightly inward from the end as shown in FIG. 5B. Further, it can be arbitrarily formed although not shown, such as a direction perpendicular to the length direction of the tape as shown in (c) and a lattice shape as shown in (d). At this time, it is preferable to form the conductive adhesive layer 1 so that the area of the conductive adhesive layer 1 is larger than the area of the electrode to be connected, because the degree of freedom in positioning the electrodes is increased.

That is, in the case of connecting an electronic component such as an IC chip 13 having an electrode arrangement of an electrode 12 having an area of a × b as shown in FIG. 6, the width b ′ of the conductive adhesive layer 1 shown in FIG. It is slightly larger than the width b. Further, although the a direction is also slightly increased, it is preferable to form it continuously in the length direction of the tape as shown in FIG. Although not shown in the figure, in the case of connection with a grid-like electrode arrangement, it is similarly formed slightly larger in a grid form as shown in FIG.
The width b ′ of the conductive adhesive layer 1 is slightly larger than the width b of the electrode, but the degree is about 1.2 to 20 times. When the magnification is low, the material cost is reduced, When the magnification is set, the degree of freedom in positioning the electrodes and the production of the continuous tape-shaped connecting member are facilitated. The distances s ′ adjacent to each other of the conductive adhesive layer 1 having conductivity shown in FIG. 5 is determined in consideration of the electrode arrangement s of the electronic component. The

FIG. 7 is a schematic cross-sectional view illustrating the conductive adhesive layer 1 having conductivity in the pressing direction. The conductive adhesive layer 1 is made of a binder 4 containing a conductive material 3. Here, as the conductive material 3, those shown in FIGS. 7A to 7G are applicable. Among these, the conductive material 3 has a particle size that can exist in a single layer in the thickness direction of the binder 4 as shown in FIGS. 7C to 7E, that is, a particle size substantially equal to the thickness of the binder 4. Since the conductive material 3 hardly flows at the time of connection, it is preferable that the conductive material 3 is easily held on the electrode. When the conductive material 3 is substantially equal to the thickness of the binder 4, it is easy to obtain conductivity because it can be electrically connected to the electrode by simple contact.
The ratio of the conductive material 3 to the binder 4 is preferably about 0.1 to 20% by volume, and more preferably 1 to 15% by volume, because anisotropic conductivity is easily obtained. Further, in order to easily obtain conductivity in the thickness direction and to achieve high resolution, the thickness of the binder 4 is preferably as thin as possible within the range in which film formation is possible, and is determined in consideration of the height of the protruding electrode, but is 30 μm. More preferably, it is 20 μm or less.

  As the conductive material 3, for example, as illustrated in FIGS. 7A to 7E, it is preferable to form the conductive material 3 because it is relatively easy to manufacture and is easily available. Further, the conductive material 3 may be provided with a through-hole in the binder 4 as shown in FIG. 7 (f) to form a conductor by plating or the like, or in the form of conductive fibers such as wires as shown in FIG. 7 (g). .

  Examples of the conductive particles include metal particles such as Au, Ag, Pt, Ni, Cu, W, Sb, Sn, and solder, carbon, and the like, and may be a simple substance, a mixture, a composite, an alloy, or the like. These conductive particles may be used as a core material, or a core material made of a polymer such as non-conductive glass, ceramics or plastic may be coated with a conductive layer made of the above-described material. Furthermore, insulating coating particles formed by coating the conductive material 3 with a thermoplastic insulating layer, and the combined use of conductive particles and insulating particles such as glass, ceramics, and plastics are applicable because the resolution is improved. In the case of insulating coating particles, the cost of the surface treatment is added to the cost of the conductive particles, resulting in an increase in cost. Therefore, the effect of reducing the conductive particles according to the present invention is large and preferable.

In order to secure one or more particles, preferably as many particles as possible, on the minute electrode, the particle size is preferably 15 μm or less, more preferably 7 μm or less and 1 μm or more. If it is less than 1 μm, it is difficult to contact the electrode through the insulating adhesive layer. Further, it is preferable that the conductive material 3 has a uniform particle diameter because there is little outflow from between the electrodes.
Among these conductive particles, those in which a conductive layer is formed on a polymer core material such as plastic, and hot-melt metal such as solder are deformable by heating or pressurization, and contact with a circuit for connection This is preferable because the area is increased and the reliability is improved. In particular, when a polymer is used as a nucleus, it does not show a melting point like solder, so that the softening state can be widely controlled by the connection temperature and it is easy to cope with variations in electrode thickness and flatness.
Also, for example, in the case of hard metal particles such as Ni and W, or particles having a large number of protrusions on the surface, the conductive particles hit the electrodes and the wiring pattern, so that even when an oxide film or a contaminated layer is present, low connection resistance Is preferable, and reliability is improved.

For the binder 4 and the insulating adhesive layer 2, a material exhibiting curability by heat or light can be widely applied, and it is preferable that the adhesive is high. Since these are excellent in heat resistance and moisture resistance after connection, application of a curable material is preferable. Among these, epoxy adhesives are particularly preferable because they can be cured in a short time, have good connection workability, and have excellent molecular adhesion.

  Epoxy adhesives are mainly composed of epoxy modified with high molecular weight epoxy, solid epoxy and liquid epoxy, urethane, polyester, acrylic rubber, NBR, silicone, nylon, etc., curing agent, catalyst, coupling agent, filling A material obtained by adding an agent or the like is generally used.

  When the binder component 4 and the insulating adhesive layer 2 of the present invention contain 1% or more, preferably 5% of a common material in each component, the interfacial adhesive force between the two layers is improved, which is suitable. As the common material, a main material, a curing agent, and the like are more effective.

  For example, the conductive adhesive layer 1 according to the present invention can be manufactured by applying the conductive adhesive layer 1 and the insulating adhesive layer 2 using a gravure roll or a roll coater provided with a weir. In addition, it is possible to adopt a method such as laminating or laminating sequentially.

  The electrode connecting method using the continuous tape-shaped connecting member of the present invention is arranged and heated and pressurized so that the insulating adhesive layer 2 of the continuous tape-shaped connecting member is on the protruding electrode side. Since the conductive adhesive layer 1 is set larger than the electrode arrangement, it is easy to align the electrodes.

  As shown in FIG. 8, the electronic component connection structure obtained as described above includes a portion having a high conductive particle density and a portion having a low conductive particle density. FIG. 8 is a schematic cross-sectional view showing a structure in which the electrode 12 formed on the substrate 11 and the protruding electrode 14 formed on the IC chip 13 are connected by the continuous tape-like connecting member according to the present invention. FIG. 8A shows a case where the conductive adhesive layer 1 exists up to the end in the length direction of the tape as shown in FIG. 5A. Similarly, FIG. This is a case where a continuous tape-like connecting member slightly inward from the end as shown in b) is used. In both connection structures, there are a portion having a high conductive particle density in the vicinity of the protruding electrode 14 and a portion having a low conductive particle density in the central portion of the IC chip 13.

According to the present invention, since the conductive adhesive layer 1 is formed only in necessary portions, the amount of expensive conductive particles used can be reduced, and valuable precious metal resources can be effectively utilized. Therefore, it is effective for reducing the cost of the continuous tape-shaped connecting member.
Since the conductive adhesive layer 1 is formed only in the necessary part and is set to be larger than the electrode arrangement, for example, even in the case of a dot-like electrode, accurate alignment is not necessary. Easy alignment.
The connection structure of the electronic component using the continuous tape-shaped connection member according to the present invention has a portion having a high conductive particle density and a portion having a low conductive particle density, and can separate the conductive function and the adhesive function, thereby obtaining the conductivity of the connection portion. It is easy to secure an effective bonding area, and the reliability and bonding strength of the connected product are improved.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
Example 1
(1) Preparation of conductive adhesive 30% solution of ethyl acetate with a ratio of liquid epoxy resin (epoxy equivalent 185) containing phenoxy resin (high molecular weight epoxy resin) and microcapsule type latent curing agent as 30/70 Got. In this solution, the surface of conductive particles in which a Ni / Au 0.2 / 0.02 μm thick metal coating is formed on polystyrene particles having a particle size of 5 ± 0.1 μm is coated with a nylon resin having a glass transition point of 127 ° C. 10% by volume of conductive particles coated with a thickness of about 0.2 μm and surface-insulated, and mixed and dispersed to obtain a conductive adhesive.
On the other hand, the conductive particles were removed from the above composition to obtain an insulating adhesive.
(2) Production of continuous tape-shaped connecting member A separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) was coated with a roll coater to obtain a sheet having a thickness of 18 μm. At this time, a weir was provided on the roll coater, and a 0.5 mm wide conductive adhesive was formed on both ends of the 1 mm wide insulating adhesive. This configuration roughly corresponds to FIG.
(3) Connection Test IC chip (1.5 × 16 mm, thickness 0.55 mm, 200 gold electrodes of 100 μm square and 15 μm height called bumps are formed in the vicinity of the end on the long piece side) and glass 0.7 mm above A thin film circuit with an indium oxide thickness of 0.2 μm (ITO, surface resistance 20Ω / □) is processed to correspond to the size of the bump electrode of the IC chip, and the connection resistance to the bump and the insulation resistance between the bumps can be measured. Then, the substrate was connected to the substrate formed with leads in the chip outer direction.
The continuous tape-shaped connecting member was placed and affixed by visual inspection so that an insulating adhesive having a width of 2 mm was disposed approximately in the center of the chip. Since it was temporarily connected to the glass electrode side, it was easy to affix, and the subsequent separator peeling was also easy. Next, the other circuit board and the upper and lower circuits were aligned, and a connection body was obtained at 150 ° C., 20 kgf / mm ² and 15 seconds.
(4) Evaluation When the connection part of this connection body was observed from the glass electrode side, conductive particles of the conductive adhesive were observed around the bump placement part, and the chip center part was connected with the insulating adhesive. When the resistance between the electrodes facing each other was evaluated as the connection resistance, and the insulation resistance between the adjacent electrodes was evaluated, the connection resistance was 1Ω or less, and the insulation resistance was 10 ⁸ Ω or more, which changed even after treatment at 85 ° C and 85% RH for 1000 hours. No long-term reliability was observed.

Comparative Example 1
Although it was the same as that of Example 1, the connection member of the conductive adhesive single layer of the conventional structure whose thickness is 18 micrometers was obtained. When evaluated in the same manner as in Example 1, the initial connection resistance was 1Ω or less and the insulation resistance was 10 ⁸ or more. However, the connection resistance increased greatly after treatment at 85 ° C. and 85% RH for 1000 hours, and an open circuit occurred. Since there are more conductive particles in the connection member than in Example 1, it is considered that this is due to a decrease in the effective adhesion area. The amount of conductive particles used was about twice that of Example 1.

Example 2
Similarly, an insulating adhesive layer (thickness 15 μm) is laminated on the other surface of the continuous tape-like connecting member of Example 1 while rolling between rubber rolls to obtain a two-layer continuous tape-like connecting member having the configuration shown in FIG. It was. The IC chip of Example 1 and a glass epoxy substrate (circuit electrode height 18 μm) were connected such that the insulating adhesive layer was on the substrate side. When evaluated in the same manner as in Example 1, the connection resistance was 1Ω or less and the insulation resistance was 10 ⁸ Ω or more, which showed good long-term reliability with little change after treatment at 85 ° C. and 85% RH for 1000 hours. .
In this example, the electrode connection was convex, but a good connection was obtained.

Example 3
On the insulating adhesive layer of Example 2 (thickness 15 μm), a 0.5 mm width conductive adhesive (no insulating coating, 5 volume% added, other specifications of Example 1) was formed by lamination. This configuration corresponds to FIG. When evaluated in the same manner as in Example 1, good connection characteristics were shown. In this example, since the conductive adhesive was formed by lamination, it was relatively easy to produce a continuous tape-shaped connecting member.
Further, the end of the connection body was connected with an insulating adhesive in addition to the center (FIG. 8b), and an extremely secure connection was obtained due to the insulation and moisture resistance.

It is a cross-sectional schematic diagram of the continuous tape-shaped connection member which shows the Example of this invention. It is a cross-sectional schematic diagram of the continuous tape-shaped connection member which shows another Example of this invention. It is a cross-sectional schematic diagram of the continuous tape-shaped connection member which shows another Example of this invention. It is a cross-sectional schematic diagram of the continuous tape-shaped connection member which shows another Example of this invention. It is a plane schematic diagram of the continuous tape-shaped connection member which shows the Example of this invention. It is a plane schematic diagram which shows the electrode arrangement | positioning of the electronic component which is one use of this invention. It is a cross-sectional schematic diagram of the electroconductive contact bonding layer which shows the Example of this invention. It is a cross-sectional schematic diagram of a connection structure showing an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Conductive adhesive layer, 2 ... Insulating adhesive layer, 3 ... Conductive material, 4 ... Binder, 5 ... Separator, 11 ... Board | substrate, 12 ... Electrode, 13 ... IC chip, 14 ... Projection electrode.

Claims (3)

In the connecting member for connecting the electrodes facing each other, a conductive adhesive layer having conductivity in the pressurizing direction composed of a conductive material and a binder and an insulating adhesive layer are alternately formed, and the conductive material The conductive adhesive layer and the insulating adhesive layer are alternately formed in a cross section when cut perpendicular to the tape length direction, and the conductive adhesive layer and the insulating adhesive layer are alternately formed. A connection member in which an insulating adhesive layer is further formed on one or both sides along the formed direction. The connection member according to claim 1, wherein an area of the conductive adhesive layer is formed larger than an electrode area to be connected. The tape-shaped connection member according to claim 1 or 2, wherein the conductive adhesive layer is formed continuously in the length direction of the tape.

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