JPH0361315B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for connecting electronic circuit members, and is particularly suitable for interconnecting electronic circuit members in which a large number of electrodes are arranged at minute intervals at connection points. It is about the method.

[Prior art and its problems]

As a method for interconnecting printed circuits, flexible printed circuits, flexible printed cables, display panels, and other electronic circuit components, methods using anisotropic conductive films are known (e.g., Electronic Technology Vol. 26, No. 7). (pp. 119-120).

In this method, first, as shown in FIG. When connecting the second electronic circuit member 16 on which a large number of electrodes 15 are formed, an anisotropic conductive film 17 is placed between them. The anisotropic conductive film 17 includes metal particles 19 in a thermosetting adhesive 18.
When this film is sandwiched between both electronic circuit members 13 and 16 and heated and pressurized, the opposing electrodes 1 are separated as shown in FIG. 2b.
Between 2 and 15, the adhesive 18 protrudes, and the metal particles 19 are sandwiched, creating electrical continuity.In other areas, the metal particles 19 remain wrapped in the adhesive 18, so that insulation is maintained. Become. In other words, the conductive film 17 exhibits anisotropy in that it conducts in the thickness direction but maintains insulation in the width direction, so that electronic circuit members with small electrode spacing can be electrically connected.

However, in the conventional method, conduction is obtained simply by sandwiching the metal particles contained in the adhesive between electrodes, so in order to lower the conduction resistance, it is necessary to increase the density of the metal particles in the adhesive. There is a problem in that increasing the metal particle density reduces the insulation between adjacent electrodes. For this reason, in the conventional method, it is difficult to simultaneously reduce the conduction resistance between opposing electrodes and improve the insulation between adjacent electrodes, which becomes a factor that inhibits high density electrodes.

[Means for solving problems and their effects]

The present invention provides a method for connecting electronic circuit members that solves the problems of the prior art as described above.
When interconnecting electronic circuit members in which a plurality of electrodes are arranged on an insulating base material at the connection point, an insulating A film in which conductive particles are dispersed in an adhesive is sandwiched, and a voltage is applied between the electrodes of both electronic circuit members while the viscosity of the insulating adhesive is reduced by heating, and the electric field generated thereby After gathering conductive fine particles near the electrodes and making the conductive fine particle density high in the area sandwiched between the electrodes and low in other areas,
This is characterized in that both electronic circuit members are bonded together under pressure.

In general, conductive particles such as gold, silver, and copper are positively or negatively charged, so if they are placed in an electric field while being free to move, they will move due to Coulomb force (or electrophoretic action). become. The present invention makes use of this phenomenon to gather conductive fine particles near the electrodes, and performs connection between opposing electrodes in a state where the density of the conductive fine particles is increased.

〔Example〕

First, as shown in FIG. 1a, a film 23 in which conductive particles 22 are dispersed in an insulating adhesive 21 is sandwiched between the electronic circuit members 13 and 16 to be connected. One electronic circuit member 13 is, for example, a printed circuit, and the other electronic circuit member 16 is, for example, a display panel. Both electronic circuit members 13,1
6 is an electrode 1 formed on one insulating base material 11
2 and an electrode 15 formed on the other insulating base material 14
are positioned so that they are facing each other. film 2
As the insulating adhesive 21 of No. 3, for example, a B-stage epoxy resin whose viscosity suddenly decreases when heated to 40 to 50°C and hardens when further heated to about 80°C is suitable, and as the conductive fine particles 22. For example, fine particles of silver or copper can be used.

Next, these are heated by being sandwiched between hot presses 24 and 25 as shown in FIG.
6 applies a voltage to the electrodes 12 and 15. Heating reduces the viscosity of the insulating adhesive 21, making the conductive fine particles 22 movable, and applying a voltage generates an electric field between the opposing electrodes 12 and 15, so that the conductive fine particles 22 exhibit electrophoretic action. For example, the particles gather near the electrode 12. As a result, the density of the conductive fine particles 22 is high in the area sandwiched between the electrodes 12 and 15, and is low in other areas.

In this state, as shown in FIG. Then, the electronic circuit members 13 and 16 are bonded.

The connection formed in this way exhibits good conductivity because high-density conductive particles are sandwiched between the electrodes, and the density of the conductive particles decreases in the areas not sandwiched between the electrodes. Therefore, good insulation is maintained.

In the above embodiments, a thermosetting resin was used as the insulating adhesive constituting the film, but a thermoplastic hot melt adhesive may also be used. In the case of hot-melt adhesives, a voltage is applied between electrodes while the adhesive is heated and melted, and then cooled to solidify the adhesive.

In addition, even if the viscosity of the insulating adhesive is reduced by heating, if the viscosity is still high and the conductive particles do not move actively, it may be possible to apply external ultrasonic vibrations to promote the movement. It will be done.

Further, if fine particles such as low melting point solder are used as the conductive fine particles, the electrodes can be fused during heat and pressure bonding.

Furthermore, magnetic powder such as iron oxide can also be used as the conductive fine particles.

〔Effect of the invention〕

As explained above, according to the present invention, the viscosity of the insulating adhesive of the film sandwiched between electronic circuit members is reduced by heating, and the conductive fine particles are applied to the electrodes by applying a voltage between the opposing electrodes. Since they are gathered nearby and bonded under pressure in that state, high-density conductive fine particles are sandwiched between the electrodes, resulting in good conductivity, and the areas not sandwiched between the electrodes are covered with conductive fine particles. This has the advantage that good insulation can be obtained because the density of the material is reduced.

[Brief explanation of drawings]

1A to 1C are sectional views showing a method for connecting electronic circuit members according to an embodiment of the present invention, and FIGS. 2A and 2B are sectional views showing a conventional method for connecting electronic circuit members. 11 - Insulating base material, 12 - Electrode, 13 - Electronic circuit member, 14 - Insulating base material, 15 - Electrode, 16 - Electronic circuit member, 21 - Insulating adhesive, 22 - Conductive fine particles, 23 - Film, 24 , 25 ~ hot press, 26 ~ power supply.

Claims (1)

[Claims] 1. When interconnecting electronic circuit members in which multiple electrodes are arranged on an insulating base material at the connection point,
A film containing conductive particles dispersed in an insulating adhesive is sandwiched between both electronic circuit members positioned so that the respective electrodes face each other, and the viscosity of the insulating adhesive is reduced by heating. A voltage is applied between the electrodes of both electronic circuit members, and the resulting electric field causes the conductive fine particles to gather near the electrodes, increasing the conductive fine particle density in the area sandwiched between the electrodes and in the other areas. A method for connecting electronic circuit members, characterized in that both electronic circuit members are bonded under pressure after being lowered.