WO1994030034A1

WO1994030034A1 - Method of electrical connection and electric circuit mounting board, and paste for executing the method

Info

Publication number: WO1994030034A1
Application number: PCT/JP1993/000807
Authority: WO
Inventors: Toranosuke Kawaguchi
Original assignee: Nihon Almit Co., Ltd.
Priority date: 1993-06-16
Filing date: 1993-06-16
Publication date: 1994-12-22

Abstract

A method for electrical connection by which the boundary between a conductive part and a non-conductive part can be recognized. A paste is prepared by kneading fine magnetic grains having a conductivity evenly with an adhesive. This paste is applied between a plurality of mutually facing electrodes which are required to be electrically connected to each other. To the electrodes, the magnetic fields having different poles (S and N poles) are applied in order to set the adhesive in a condition that the concentration of conductive fine magnetic grains is high only between the electrodes which face each other.

Description

Satsuki Itoda »Electrical connection method and circuit board for electrical circuit mounting and paste for electrical connection method

The present invention relates to an electrical connection method for electrically connecting required parts such as electronic parts such as ICs, an electric circuit mounting board obtained by this method, and a paste for an electrical connection method used in this method. Related. Background art

Conventionally, an electrical connection method for electrically connecting required parts of electronic components such as IC has been proposed in Japanese Patent Application Laid-Open No. 51-106679.

In this conventional example, as shown in FIG. 3, for example, conductive paste 1 made of copper, silver, gold, or the like is kneaded with an adhesive 2 to form a paste, and a paste is formed on the inner surface of an adhesive tape (not shown). Then, a conductive adhesive thin film having conductivity is prepared.

Next, a thin film composed of the conductive fine particles 1 and the adhesive 2 is placed between the plurality of electrodes 4 and 6 provided on the tape 3 and the glass substrate 5 and facing each other up and down. The kneaded adhesive 2 is cured by raising the temperature while a pressing force is applied between 6.

In this manner, as shown in FIG. 4, conductivity appears only in the portion where the pressing force is applied by the upper and lower electrodes 4 and 6, and the lateral insulation other than this portion is secured. In general, conductive fine particles 1 having a diameter of 3 to 15 m are dispersed in an adhesive 2. In the adhesive 2, the conductive fine particles 1 are dispersed and independent as shown in FIG. 3. And exist Therefore, the adhesive 2 is an insulator. This is sandwiched between the electrodes 4 and 6 that are to be electrically connected, and heated and pressurized (150 ° C, 20 to 50 kgf Zcm ² ), thereby forming the upper and lower electrodes 4 and 6. Electrical conduction and bonding between them are performed simultaneously.

However, in the above-mentioned conventional example, since the conductive metal is widely dispersed also in the non-pressurized portion, it is necessary to clearly distinguish the two at the boundary between the conductive portion and the non-conductive portion. Is difficult, and even if a conductor portion is generated, its conductivity is not good. In particular, in the current situation where the pitch width of electric circuits is becoming narrower, this should be particularly noted, and this is an obstacle.

In view of the above, the present invention more clearly identifies the boundary between the conductive portion and the non-conductive portion, increases the metal composition concentration at the bonding portion, and obtains high conductivity regardless of the thickness of the adhesive layer. An object of the present invention is to provide an electrical connection method that can be performed, an electric circuit mounting board obtained by the method, and a paste for an electrical connection method used in the method. Disclosure of the invention

The present invention provides a paste in which conductive magnetic fine particles are uniformly kneaded with an adhesive, and the paste is interposed between a plurality of opposed electrodes that need to be electrically connected to each other, A magnetic field having different polarities (S, N poles) is applied to the electrodes to increase the concentration of the conductive magnetic fine particles only between the opposing electrodes, and the temperature is increased in this state, or at room temperature. This is an electrical connection method characterized by curing the adhesive by leaving it to stand.

Further, according to the present invention, on the upper and lower surfaces of the paste containing the conductive magnetic fine particles uniformly coated on the release paper, only the portions corresponding to the conductive portions of the electric circuit are magnetized to the N pole and the S pole, respectively. Two permanent magnet plates An electric circuit mounting board characterized in that the resin in the paste is cured while being in contact therewith.

Further, the present invention is a paste for carrying out an electrical connection method, wherein magnetic fine particles having conductivity used in the electrical connection method are uniformly kneaded with an adhesive.

According to the present invention, magnetic fine particles having conductivity in an adhesive or an adhesive sandwiched between the upper and lower surfaces of an adhesive film (for example, nickel powder, or copper plating to increase conductivity). Dispersed iron powder, etc.), and apply a magnetic field with a permanent magnet or electromagnet across the opposing electrodes that require electrical connection. By this magnetic field, the conductive magnetic fine particles suspended and dispersed in the uncured adhesive are collected between the electrodes, and the concentration of the conductive magnetic fine particles is increased. In this state, the temperature is increased, or the temperature is increased at room temperature. The adhesive is cured by leaving it unattended, and the electrodes are electrically connected. At this time, phenol, epoxy, or the like is used as the thermosetting resin as the adhesive, and the curing conditions include, for example, holding at 150 ° C. for several minutes. On the other hand, an acrylic resin or the like is used as the room-temperature curing resin, and the curing conditions are 25 ° C. for 180 minutes or 100 ° C. for 10 minutes. is there. For this reason, compared with the case where only the pressing step in the related art is used, the boundary between the electrically conductive portion and the non-conductive portion can be clarified, and the conductivity of the conductive portion can be increased.

As described above, the present invention makes it easy to clearly identify the boundary between the conductive portion and the non-conductive portion, and fully exerts the anisotropic effect of increasing the conductivity. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram of a first embodiment of the present invention, FIG. 2 is an explanatory diagram of a second embodiment of the present invention, and FIGS. 3 and 4 are explanatory diagrams of a conventional example. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is an explanatory diagram of a first embodiment of the present invention. Electrodes 4 and 6 are provided on the polyimide tape 3 and the glass substrate 5, respectively, and a paste composed of conductive magnetic fine particles 1a and an adhesive 2 is interposed between the electrodes 4 and 6. . Next, the permanent magnets 7, 8 placed directly above or below the polyimide tape 3 and the electrodes 4, 6 on the glass substrate 5, respectively, are placed between the electrodes 4, 6. By applying a magnetic field, the conductive fine particles 1 a can be concentrated between the electrodes 4 and 6.

Next, in this state, the thermosetting resin 2 is cured by increasing the temperature, and the electrodes 4 and 6 are electrically connected to each other. After this electrical connection, the permanent magnets 7, 8 are removed. The polyimide tape 3 and the glass substrate 5 are held together with the electrodes 4, 6 as they are. Further, the materials of the polyimide tape 3 and the glass substrate 5 are not limited, and may be made of ceramics or the like.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention. First, a paste is prepared by uniformly kneading magnetic fine particles 1a having conductivity with a thermosetting resin 2 as an adhesive. Next, a paste is interposed between a plurality of opposing electrodes 4 and 6, which need to be electrically connected to each other. The electrodes 4 and 6 are made of a magnetic or non-magnetic metal. Next, for example, a magnetic field having different polarities (S, N poles) is formed on the electrodes 4, 6 by the permanent magnets 7, 8 provided respectively on the tape 3a and the tape 5a made of epoxy resin or the like. To increase the conductive composition concentration of the magnetic fine particles 1a having conductivity only between the opposing electrodes 4 and 6. Further, the temperature is increased under such circumstances, and the thermosetting resin 2 is cured. As a result, only the electrodes 4 and 6 are electrically connected. Furthermore, after the above work is completed, the epoxy with permanent magnets 7, 8 Remove tape 3a and tape 5a made of resin or the like.

In the embodiment shown in FIG. 2, electrodes 4 and 6 are provided on a polyimide tape 3 and a glass substrate 5, respectively, and a paste composed of conductive magnetic fine particles 1a and a bonding agent 2 is used as the electrode 4. , 6 interposed. Next, the permanent magnets 7 and 8 placed directly above or below the polyimide tape 3 and the electrodes 4 and 6 on the glass substrate 5 respectively cause a magnetic field between the electrodes 4 and 6. The particles 1 a having conductivity are concentrated between the electrodes 4 and 6 by acting.

In the embodiments of FIGS. 1 and 2 described above, the permanent magnets 7 and 8 apply a magnetic field to the electrodes 4 and 6 to raise the temperature to cure the thermosetting resin 2, and at the same time, By applying a pressing force to 6, the conductive fine magnetic particles 1a contained in the base may be plastically deformed to increase the conductive concentration of the conductive magnetic fine particles 1a. The means for applying a magnetic field to the electrodes 4 and 6 is preferably a strong permanent magnet, but may be an electromagnet. The conductive magnetic fine powder la may be a fine powder of Fe, Ni, Co, Cr, or the like, or an alloy thereof, or a magnetic powder of another metal or alloy. It is made of coated metal or conductive metal coated with magnetic metal or alloy.

More specifically, the conductive fine particles 1a are made of, for example, an iron powder coated with copper plating, a nickel powder, or an anisotropic acicular metal powder coated with copper plating. . For example, a needle-shaped copper plating When iron powder is used, the conductive anisotropy of the present invention can be more remarkably exhibited.

Pb—Sn solder powder may be subjected to nickel plating having magnetic properties. For example, in an epoxy resin as a thermosetting resin 2, nickel powder as a magnetic fine powder 1a having conductivity reduced by hydrogen is sufficiently mixed at a volume ratio of 5 to 10 with respect to the epoxy resin. Use the kneaded material. Reduced nickel powder obtained from carbonyl nickel is economical in price. In some cases, the thermosetting resin 2 may contain an epoxy-based acryl resin having an adhesive property of 2 to 3 percent (volume ratio).

When a thermosetting resin is used as the resin, the curing temperature is preferably up to about 150 ° C, and it is necessary to appropriately select the resin mixing ratio at this time. There is. At this curing temperature, the problem of magnetic deterioration of the strong permanent magnet described above does not occur. Also, instead of the thermosetting resin 2 such as an epoxy resin, an acrylic resin which is a room-temperature curing resin may be used as the adhesive.

When a room temperature curing resin is used, it is naturally cured by leaving it at room temperature for a predetermined time. In this case, it is possible to prevent the mounted components and the like from being thermally degraded due to the curing temperature of the adhesive.

As another embodiment described above, only the portions corresponding to the conductive portions of the electric circuit on the upper and lower surfaces of the paste containing the conductive magnetic fine particles uniformly coated on the release paper are respectively N-pole and S-pole. The resin in the paste can be cured while the two permanent magnet plates magnetized to the poles are in contact with each other to obtain an electric circuit mounting substrate.

Claims

青 C..... 1 1............ 1 1 1 1 1.. ..

The paste is interposed between a plurality of opposing electrodes that need to be electrically connected to each other,

A magnetic field having different polarities (S, N poles) is applied to the electrodes to increase the concentration of the conductive magnetic fine particles only between the opposing electrodes, and the temperature is increased in this state or left at room temperature. Thereby curing the adhesive.

2. At the same time as applying a magnetic field to the electrode to cure the adhesive and further applying a pressing force by a permanent magnet acting on the electrode, the arrangement of the magnetic fine particles contained in the paste is different. 2. The electrical connection method according to claim 1, wherein anisotropy is enhanced, and a boundary between the conductive part and the insulated part is further clarified by the magnetic fine particles having conductivity.

3. The magnetic fine particles having conductivity include magnetic fine particles of Fe, Ni, Co, and Cr or alloys thereof, or coatings of these magnetic fine particles with other metals or alloys. The electrical connection method according to claim 1, wherein the electrical connection method is formed by applying a magnetic metal or an alloy to the conductive metal powder.

4. The electrical connection method according to claim 1, wherein the adhesive is made of a thermosetting resin or a room temperature setting resin.

5. On the upper and lower surfaces of the paste containing the conductive magnetic fine particles uniformly coated on the release paper, only the portions corresponding to the conductive portions of the electric circuit are removed. A substrate for mounting an electric circuit, characterized in that the resin in the paste is hardened while two permanent magnet plates magnetized to the N pole and the S pole are in contact with each other.

6. A paste for carrying out an electrical connection method, wherein conductive magnetic fine particles are uniformly kneaded with an adhesive.