JPH10284817A - Circuit connecting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered structure having a migration resistance and a high current resistance by constituting a circuit on a hard substrate in such a connecting structure that the surface layer of a multilayered circuit consisting of a plurality of layers is harder than the next layer and at least conductive particles which are harder than those pushed in the next layer are partially pushed in a multilayered circuit layer on the hard substrate. SOLUTION: A circuit connecting structure is composed of a hard substrate 1 and a multilayered circuit of a surface-layer circuit 2 and a next-layer circuit 3, a wiring board 8 composed of a circuit 6 and a substrate 7, and a connecting member 9 composed of conductive particles and a bonding agent 5. The surface- layer circuit 2 is relatively harder than the send-layer circuit 3 and part of the conductive particles 4 are pushed in both the circuits 2 and 3 which are provided on the substrate 1. In the multilayered circuit, the end face of the next-layer circuit 3 is exposed, but the occurrence of migration can be prevented, because the surface of the circuit 3 is coated with the surface-layer circuit 2. The circuit formed on the substrate 1 can be formed in a high multilayered structure so that the resistance of the circuit may be reduced and the circuit may resist a large current and a high voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure of a circuit used for an electric or electronic circuit board using a connection member made of conductive particles and an adhesive.

[0002]

2. Description of the Related Art In recent years, as electronic components have become smaller and thinner, circuits used for them have become higher in density and higher in definition. Since it is difficult to connect electrodes of such electronic components to microcircuits using conventional solder or rubber connectors, recently, anisotropic conductive adhesives or films (hereinafter referred to as “connections”) having excellent resolution are used. Members) are frequently used. This connection member
It is made of an adhesive containing a predetermined amount of conductive material such as conductive particles, and this connecting member is provided between an electronic component and a substrate or between an electrode or a circuit, and by heating or heating / pressing means, the two members are connected. The electrodes are electrically connected,
The electrodes formed adjacent to the electrodes are provided with insulating properties, and the electronic component and the circuit are bonded and fixed.

[0003] The basic idea for increasing the resolution of the connection member is to make the particle size of the conductive particles smaller than the gap between the adjacent electrodes to ensure insulation between the adjacent electrodes, and at the same time, to make the conductive particles smaller. By ensuring that the particles do not come into contact with each other, and by ensuring that the particles are present on the electrodes, conductivity at the connection portion is obtained.

On the other hand, in recent years, for example, in electroluminescence and plasma display applications, electronic
It has become necessary to supply a high current and a high voltage to the electronic circuit board. Until now, such electrodes and circuits have used Ag
And an Al electrode are often used, and pressure connection by a clip and solder connection have been adopted for connection.

[0005]

There are several problems with the above-described circuit connection structure. For example, when the Al electrode or the surface is formed of an oxidizing metal, the surface of the electrode is easily oxidized, and a low-resistance connection enduring a high current and a high voltage cannot be obtained. In the case of a thin-film electrode with no electrode height,
Similarly, a low resistance cannot be obtained. With the recent trend toward higher density and higher definition of electrodes and the like, miniaturization of the electrodes is required, and therefore, it is not possible to cope with the miniaturization by the conventional pressure welding method using a clip and soldering. Furthermore, the Ag circuit electrode has migration when energized, and has a problem in durability. Accordingly, an object of the present invention is to establish a circuit connection structure for satisfying high current, high voltage, miniaturization, and migration resistance.

[0006]

According to the present invention, there is provided a circuit connection structure in which opposing circuits provided on a hard substrate and a wiring substrate are connected by a connection member made of conductive particles and an adhesive. The upper circuit is a multi-layer circuit composed of two or more layers, the multi-layer circuit having a surface layer that is relatively harder than the next layer, conductive particles being harder than the next layer, and a multi-layer circuit layer on a hard substrate. Is a connection structure of a circuit in which at least a part thereof is pressed. Further, as this embodiment, in a multilayer circuit, connection of a circuit in which the surface layer is 3.5 or more specified by the Mohs Katasa standard, the next layer is less than 3.5, and the thickness of the multilayer circuit is 0.5 μm or more Regarding the structure.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. 1 and 2 show a circuit connection structure for explaining an embodiment of the present invention. The connection structure of the circuit of the present invention is a rigid substrate 1
And a two-layer circuit composed of a surface layer 2 and a next layer 3 provided thereon, a wiring substrate 8 composed of a circuit 6 and a substrate 7, and a connection member 9 composed of conductive particles 4 and an adhesive 5.
At this time, in the present invention, the surface circuit 2 is relatively harder than the next layer circuit 3, and both the surface circuit 2 and the next layer circuit 3 (FIG. Only the circuit 3 (FIG. 2) is characterized in that a part of the conductive particles 4 is pressed. As shown in FIG. 3, in addition to the surface layer circuit 2 and the next layer circuit 3 on the hard substrate 1, another circuit 10 is provided.
It may have a three-layer structure or a multilayer structure of more layers. In FIGS. 1-3, in the multilayer circuit,
Although the end face of the next layer circuit is exposed, covering the surface of the next layer circuit with the surface layer circuit 2 as shown in FIG.

In FIGS. 1 to 3, the circuit on the hard substrate 1 has a multilayer structure so as to withstand low resistance, withstand high current and high voltage. In the present invention, the material of the surface layer circuit 2 is Mo.
Cr (Mohs Katasa; 9.0, specific resistance 20 ° C .; 18.9) which is 3.5 or more specified in hs Katasa standard and has excellent conductivity
μΩ · cm), and Ni (3.8,
6.9 μΩ · cm), Pt (4.3, 10.6 μΩ ·
cm), W (6, 5.5 μΩ · cm) Fe (4.5,
9.8 μΩ · cm) can be applied. Next layer circuit 3
For materials of less than 3.5 specified in Mohs Katasa standard,
Au (Mohs Katasa; 2.5, specific resistance 20) with excellent conductivity
° C; 2.4 µΩ · cm).
(2.7, 1.62 μΩ · cm), Cu (3.0, 1.
72 μΩ · cm). In addition, the thickness of the multilayer circuit on the hard substrate is 0.5 μm or more, and is preferably 0.5 to 15 μm, and
m is more preferred. The Mohs Katasa standard referred to in the present invention is specified in the Chemical Handbook issued by Maruzen Co., Ltd. edited by The Chemical Society of Japan. For example, Na (0.4), S (2.0), Mn
(5.0) and B (9.5).

[0009] In the case of a three-layer circuit, the material of the other circuit 10 is not specified by Katasa, and as shown above, the surface circuit 2
Also, those having excellent conductivity as used in the next layer circuit 3 are preferable. As the conductive particles, it is preferable that the conductive particles are harder than the circuit on the hard substrate 1. However, since the multilayer circuit is formed from a different material, the layer having a smaller size than the conductive particles is formed in the multilayer circuit. At least one layer is present but required. That is, it is preferable that the length of the conductive particles is larger than that of the next layer circuit 3 or another circuit 10. In consideration of the pushing of the conductive particles, it is more preferable that the length of the conductive particles is larger than that of the next layer circuit 3. Materials for the conductive particles include metal particles such as Ni, Pt, W, Cr, and Sb, alloys thereof, composites, and carbon powders. In order to further improve conductivity, these may be used as cores, Alternatively, conductive coated particles obtained by using a material made of a polymer such as non-insulating glass, plastic, or ceramic as a core and coating with a material having good conductivity are preferable. Applicable particle size of conductive particles is 30μm or less in order to be easily pushed into the circuit on the hard substrate, and to make the particle size of the conductive particles smaller than the insulating part between adjacent electrodes to cope with miniaturization of the circuit. In consideration of connection reliability, the average particle diameter is 2 to 2.
25 μm is preferable, and 3 to 15 μm is more preferable. It is preferable that the shape of the particles is spherical because the pressing force at the time of connection is directly transmitted to the circuit. At this time, if the surface has irregularities, it is easy to cut into the surface layer circuit.

The connecting member is made of an adhesive containing 0.1 to 20% by volume of conductive particles based on the adhesive composition or the film adhesive. As the adhesive, a material that shows curing by applying energy such as heat, light, or radiation can be widely applied, and preferably has adhesiveness. Since these are excellent in heat resistance and moisture resistance after connection, cured materials are preferable. Further, the glass transition point Tg, which is the thermal inflection point of the adhesive, is preferably 130 ° C. or more, which is excellent in heat resistance, because long-term reliability is required for circuit connection.

In the present invention, by defining the shape of the circuit on the rigid substrate and the shape of the conductive particles, the particles are easily pushed into the circuit by heating and pressurizing at the time of connection, and the contact area of the connection portion is reduced. Since it increases, resistance can be reduced. As a result, even when the circuit is composed of two or more layers and the thickness of the circuit is increased, a good low connection resistance can be obtained, so that high current and high voltage can be maintained. In addition, since the occurrence of migration, which is likely to occur when a single layer of Ag alone is used, can be prevented by forming a multilayer circuit and using a metal with low ionization on the surface,
The durability is significantly improved. In the present invention, a fine circuit can be connected by setting the conductive particle diameter to 30 μm or less. Further, by making the particle diameter larger than the height of the circuit 3, which is a circuit on a hard substrate, it is easy to take measures to push the circuit into the circuit. Further, by setting the length of the circuit of the wiring board equal to or more than that of the conductive particles, the connection structure of the present invention can be easily achieved.

[0012]

EXAMPLES Next, examples will be described, but the present invention is not limited to these examples.

Example 1 (1) Circuit on Hard Substrate On a 1.7 mm thick glass as a hard substrate, C
r (thickness: 0.2 μm), Cu (2 μm) and Cr
(0.2 μm) A circuit on a hard substrate having a height of 2.4 μm and having a circuit is used.

(2) Preparation of connection member The ratio of a phenoxy resin (high molecular weight epoxy resin) to a liquid epoxy resin containing a microcapsule type latent curing agent (epoxy equivalent 185) as a film forming material is 30.
/ 70 to give a 30% solution of ethyl acetate. This solution has an average particle diameter of 8 μm, a maximum particle diameter of 15 μm, and a minimum particle diameter of 3 μm.
1% by volume of conductive particles having Au coatings having better conductivity than Ni of 0.01 μm or more formed on the surface of the Ni particles of m were mixed and dispersed. This dispersion is separated with a separator (silicon-treated polyethylene terephthalate film, thickness 50 μm).
m) with a roll coater to obtain a 35 μm thick sheet.

(3) Connection 5 μm high with Cr / Cu / Cr circuit on glass substrate
m on a rigid substrate (electrodes of a parallel circuit with a circuit pitch of 330 μm and an electrode width of 115 μm) and 40 μm high copper on a polyimide film with Ni plating (thickness: 2 μm) and further Au plating (thickness: 0.5 μm) FPC (circuit pitch: 330 μm, electrode width: 150)
(electrodes of a parallel circuit of μm). The connecting member was placed on a hard substrate with a width of 2 mm, and the separator was peeled off and attached. Since it was temporarily connected to the circuit side on the hard substrate, it was easy to attach it, and the subsequent separation of the separator was also easy. Next, the upper and lower circuits were aligned with another circuit board, and a connection was obtained by heating and pressing at 150 ° C., 20 kgf / cm 2, and 15 seconds.

(4) Evaluation The cross section of this connection body was polished and observed with an electron microscope. As a result, the connection structure was equivalent to that of FIG. The conductive particles on the electrode deformed the surface layer and the next layer on the hard substrate, and were pressed by 0.1 μm or more. The space between the adjacent electrodes had no bubbles, the conductive particles were dispersed, and the insulation between the electrodes was maintained. The connection resistance between the opposing electrodes was evaluated as the connection resistance, and the insulation between the adjacent electrodes was evaluated as the insulation resistance.
Ω or less, and the insulation resistance was 108 Ω or more. Adhesive T
g at 130 ° C. or higher, these are 85 ° C., 8
5% RH 1000 hours treatment and heat cycle (-55
(° C. to 125 ° C.) Even after the treatment, there was almost no change, migration could be prevented, and good long-term reliability was exhibited.

Embodiment 2 Same as Embodiment 1, except that the circuit on the rigid substrate is
r / Al / Cr (thickness: 0.2 μm / 2 μm / 0.2 μ
m). The evaluation was performed in the same manner as in Example 1. As a result, good long-term reliability was exhibited in the insulating property and the connection resistance.
The connection cross section was equivalent to FIG. 3, and particles penetrated into the surface layer and the next layer.

Embodiment 3 Same as Embodiment 1, except that the circuit on the rigid substrate is
r / Cu / Al (thickness: 0.2 μm / 2 μm / 0.2 μ
m). The evaluation was performed in the same manner as in Example 1. As a result, good long-term reliability was exhibited in the insulating property and the connection resistance.
The connection cross section was equivalent to FIG. 3, and particles penetrated into the surface layer and the next layer.

Example 4 Same as Example 1, except that the configuration of the circuit on the hard substrate was changed to Cr / Ag (thickness: 0.2 μm / 2 μm), and the next layer was formed by the surface layer circuit. Coated. When evaluated in the same manner as in Example 1, no migration occurred when Ag was the surface layer, and good long-term reliability was exhibited in insulation and connection resistance. The connection cross section was equivalent to FIG. 4, and particles penetrated into the surface layer and the next layer.

Fifth Embodiment The same as the first embodiment, except that the configuration of the circuit on the rigid substrate is C
The structure was changed to a two-layer structure of r / Al (thickness: 0.2 μm / 2 μm). The evaluation was performed in the same manner as in Example 1. As a result, good long-term reliability was exhibited in the insulating property and the connection resistance. The connection cross section was equivalent to FIG. 1, and particles penetrated into the surface layer and the next layer.

Embodiment 6 The same as embodiment 1 except that the circuit on the hard substrate is
t / Cu (thickness: 0.2 μm / 2 μm). The evaluation was performed in the same manner as in Example 1. As a result, good long-term reliability was exhibited in the insulating property and the connection resistance. The connection cross section is equivalent to FIG. 2, and the particles pierced the surface layer, deformed the next layer, and digged.

Example 7 The same as Example 1 except that the average particle size of the W particles having a particle size of 10 μm, the maximum particle size of 15 μm, and the minimum particle size of 5 μm was 0.01 μm.
The structure of the circuit on the hard substrate is Cr / Cu / Al using conductive particles formed with Au coating which is more conductive than W
(Thickness: 0.2 μm / 2 μm / 0.2 μm).
The evaluation was performed in the same manner as in Example 1. As a result, good long-term reliability was exhibited in the insulating property and the connection resistance. Figure 3 shows the connection section
It was considerable, and the particles penetrated into the surface layer and the next layer.

[0023]

As described above in detail, according to the present invention, it is possible to provide a circuit connection structure excellent in high current, high voltage, miniaturization and migration resistance.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a circuit connecting portion for explaining an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a circuit connecting portion for explaining another embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a circuit connecting portion for explaining another embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a circuit connection section for explaining another embodiment of the present invention.

[Explanation of symbols]

 1 Hard board 2 Surface layer circuit Tertiary layer circuit 4 Conductive particles 5 Adhesive 6 Circuit 7 Board 8 Wiring board 9 Connection member 10 Other circuit

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[Procedure amendment]

[Submission date] April 11, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

(3) Connection 5 μm high with Cr / Cu / Cr circuit on glass substrate
m on a rigid substrate (electrodes of a parallel circuit with a circuit pitch of 330 μm and an electrode width of 115 μm) and 40 μm high copper on a polyimide film with Ni plating (thickness: 2 μm) and further Au plating (thickness: 0.5 μm) FPC (circuit pitch: 330 μm, electrode width: 150)
(electrodes of a parallel circuit of μm). The connecting member was placed on a hard substrate with a width of 2 mm, and the separator was peeled off and attached. Since it was temporarily connected to the circuit side on the hard substrate, it was easy to attach it, and the subsequent separation of the separator was also easy. Next, the upper and lower circuits were aligned with another circuit board, and a connection was obtained by heating and pressing at 150 ° C., 20 kgf / cm ² , and 15 seconds.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

(4) Evaluation The cross section of this connection body was polished and observed with an electron microscope. As a result, the connection structure was equivalent to that of FIG. The conductive particles on the electrode deformed the surface layer and the next layer on the hard substrate, and were pressed by 0.1 μm or more. The space between the adjacent electrodes had no bubbles, the conductive particles were dispersed, and the insulation between the electrodes was maintained. The connection resistance between the opposing electrodes was evaluated as the connection resistance, and the insulation between the adjacent electrodes was evaluated as the insulation resistance.
Ω or less, and the insulation resistance was 10 ⁸ Ω or more. Adhesive T
g at 130 ° C. or higher, these are 85 ° C., 8
5% RH 1000 hours treatment and heat cycle (-55
(° C. to 125 ° C.) Even after the treatment, there was almost no change, migration could be prevented, and good long-term reliability was exhibited.

Claims (2)

[Claims] 1. A circuit connection structure in which opposing circuits provided on a hard substrate and a wiring substrate are connected by a connection member made of conductive particles and an adhesive, wherein the circuit on the hard substrate has two or more layers. In these multilayer circuits, the surface layer is relatively harder than the next layer, the conductive particles are harder than the next layer, and at least a part of the multilayer circuit is pressed into the multilayer circuit layer on the rigid substrate. The connection structure of the circuit. 2. The multilayer circuit according to claim 1, wherein the surface layer is Moh.
s A connection structure of a circuit in which the thickness of a multilayer circuit is not less than 3.5 and the thickness of a multilayer circuit is not less than 3.5, and the thickness of a multilayer circuit is not less than 3.5 specified in the Katasa standard.