JPH0799201A - Method for connecting electrode - Google Patents

Abstract

PURPOSE:To simplify the method for directly connecting, electrodes of electronic components and devices to electrodes provided on printed circuit boards, etc., and for decreasing costs. CONSTITUTION:Solvent 5 containing solder-plating magnetic particles 6 is coated in the area where an electrode 2, present on a printed circuit board 1, is placed, and the particles 6 in the solvent are forced to concentrate on the electrode 2 in the magnetic field of magnets 7 and 8. Then under this situation, the solvent is made to volatile, and the concentrated particles are baked to produce a bump 9. With this method, bumps are produced inexpensively through no highly controlled process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for directly connecting an electrode of an electronic component or an electronic device to an electrode of a connection partner without using a lead such as a wire.

[0002]

2. Description of the Related Art Generally, when electrically connecting electrodes of electronic parts and electronic devices, it is common to make an indirect connection through a bonding wire or the like, but recently, with the miniaturization of electronic circuits, A method of overlapping electrodes and directly connecting them has been devised and often used. For example, a method of forming bumps of solder or the like on the electrodes, melting the bumps in a reflow furnace, and joining the stacked electrode to the lower electrode is a typical example of this direct connection.

[0003]

The above-mentioned solder bump or the like has a high cost because it is manufactured by a process which requires a complicated and extremely high degree of control, and is therefore preferable in terms of downsizing of an electronic circuit. However, there is a problem that the field of use is limited in terms of cost even though it is known.

[0004] Therefore, an object of the present invention is to make direct connection between electrodes relatively easy, inexpensive and reliable.

[0005]

The method of the present invention, which was developed to solve the above-mentioned problems, applies a solvent containing conductive particles of a magnetic material onto an electrode, and further applies a magnetic field in the direction perpendicular to the electrode. The applied conductive particles are concentrated on the bonding surface of the electrode by applying, the solvent is volatilized in this state, and the conductive particles are sintered to form a bump, and the bump is connected to the electrode as a bonding material. It is to join the electrodes of the other party.

Another method is to apply an adhesive solution containing conductive particles of a magnetic material onto an electrode, and then apply a magnetic field to the electrode in the vertical direction to apply the applied conductive particles to the bonding surface of the electrode. It is concentrated on the upper side, and in this state, the electrode of the connection partner is overlapped on the electrode to solidify the adhesive liquid.

The conductive particles used in the former method have a low melting point (preferably 350 ° C.) of lead, tin, solder or the like in the magnetic particles so that sintering and melting at the time of joining the mating electrodes can be performed at a low temperature.
The following is preferable to be provided with a metal coating.

[0008]

According to the method of the present invention, the magnetic conductive particles in the solvent or the adhesive solution are concentrated on the electrodes by the magnetic field. Therefore, there is no need to go through complicated steps as in the conventional solder bump formation, and high-level control is also possible. do not need.

Further, since the conductive particles are surely connected to each other to form the conductive path, the connection can be made with higher reliability than the method of obtaining the electric conduction through the conductive paint.

It is not preferable that the electronic parts and the electronic device are exposed to a high temperature when the conductive particles are sintered or when the bumps made of the conductive particles are melted. Since the conductive particles having the coating of the low melting point metal described above can be sintered and melted at a low temperature, the unfavorable situation can be avoided.

[0011]

1 and 2 show a concrete example of the connection method of the present invention. Here, the case where the semiconductor chip is directly connected to the electrodes on the printed circuit board is taken as an example. In both figures, 1 is a printed circuit board, 2 is an electrode on the board, 3 is a semiconductor chip, and 4 is an electrode on the chip side connected to the electrode 2.

In the method of FIG. 1, as shown in the figure, the solvent 5 is applied to the electrode forming region on the substrate 1. The solvent 5 used here is solder-plated magnetic particles 6 in a volatile liquid.
Are dispersed.

Next, as shown in the figure, magnets 7 and 8 having different polarities are arranged to face each other with the electrode 2 in between.
A magnetic field perpendicular to the bonding surface of the electrode 2 is applied to the solvent 5
The solder-plated magnetic particles 6 are concentrated on the electrode 2.
Then, keeping this state, the whole substrate is placed in a heating atmosphere. As a result, the liquid volatilizes and disappears, and the remaining solder-plated magnetic particles 6 are sintered to form bumps 9 on the electrode 2 as shown in the figure. Therefore, thereafter, the electrodes 4 of the semiconductor chip 3 are stacked on the bumps 9 as in the conventional case, and the bumps 9 are melted in a reflow furnace (melting is solder on the particle surface) to bond the electrodes 2 and 4.

The basic method of the second method shown in FIG. 2 is the same as that of FIG. That is, in this method, the solvent 1
As the material 5, magnetic particles 16 dispersed in an adhesive solution are used, and this solvent is applied to the electrode formation region on the substrate. Then, similarly to the method of FIG. 1, the magnetic particles 16 are concentrated on the electrode 2 by utilizing the magnetic fields generated by the magnets 7 and 8. In the method of FIG. 2, thereafter, the electrode 4 of the semiconductor chip is superposed on the electrode 2 while maintaining the magnetic particles 16 in a concentrated holding state, and the adhesive is solidified. In this method, since the bonding state of the electrodes 2 and 4 is maintained by the adhesive force of the adhesive, the magnetic particles 16 may or may not have good sinterability, but in view of the electrical characteristics of the connecting portion, the surface has good conductivity. Those provided with a coating of a functional metal are preferable. Further, since the bonding force per unit area is smaller in the bonding by the adhesive than in the bonding by the bump, it is desirable to bond the entire chip 3 as shown in FIG.

[0015]

As described above, the connection method of the present invention allows electrodes to be connected to each other with high reliability without going through a highly controlled process, and is directly connected from the economical and reliability points of view. Since it can be used for parts and devices that have limited connections, it helps increase the popularity of small electronic circuits.

[Brief description of drawings]

FIG. 1 is a process chart showing an example of a method of the present invention.

FIG. 2 is a process diagram showing an example of another connection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Electrode 3 Semiconductor chip 4 Electrode 5,15 Solvent 6 Solder plating magnetic substance particle 16 Magnetic substance particle 7,8 Magnet 9 Bump

Claims (2)

[Claims] 1. A solvent containing magnetic conductive particles is applied onto an electrode, and a magnetic field is applied in a direction perpendicular to the electrode to concentrate the applied conductive particles on the bonding surface of the electrode. The method of connecting electrodes, wherein the solvent is volatilized and the conductive particles are sintered to form bumps, and the electrodes of the connection partner are bonded onto the electrodes using the bumps as a bonding material. 2. An adhesive liquid containing magnetic conductive particles is applied onto an electrode, and a magnetic field is applied in a direction perpendicular to the electrode to concentrate the applied conductive particles onto the bonding surface of the electrode. In the state, an electrode of a connection partner is overlaid on the electrode to solidify the adhesive liquid, and the electrode connecting method.