JPH0897256A - Method of mounting electronic part - Google Patents

Abstract

PURPOSE: To provide a method of mounting an electronic part capable of detecting any defective electronic part and defective connection as well as easily removing electronic part. CONSTITUTION: Conductive particles 13 whereon a thin thermoplastic bonding agent layer 17 is formed are dispersed on a glass substrate 12, a semiconductor chip 19 is put thereon in place. Later, an Au layer 16 is exposed from the thermoplastic bonding agent layer 17 by heating and pressing steps so as to make a bump electrode 18 and an ITO wiring 11 conductive. At this time, since the thermoplastic bonding agent layer 17 supports the semiconductor chip 19 and the glass substrate 12 by feeble bonding force, the conduction test, etc., can be performed in such a state thereby enabling the electronic parts to be rebonded. In such a state, when an insulating resin is injected between the semiconductor chip 19 and the glass substrate 12, both elements can be bonded together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining electronic components, and more particularly to a method for joining electronic components to a wiring board in a state where they are electrically connected by using conductive particles.

[0002]

2. Description of the Related Art Conventionally, as a method for joining electronic components of this type, as shown in FIG. 8, an anisotropic conductive adhesive 3 made by mixing conductive particles 1 with a thermosetting adhesive 2 is used for bonding. Techniques for making them known are known. This method starts with wiring pattern 5
The wiring substrate 4 having the wirings formed therein is prepared, and as shown in FIG. 8A, the anisotropic conductive adhesive 3 is transferred to the region of the substrate 4 where the IC chip is bonded (mounted). Next, FIG.
As shown in (B), the wiring board 4 and the IC chip 6 are superposed so that the protruding electrodes 7 of the IC chip 6 face the wiring pattern 5 via the anisotropic conductive adhesive 3. Then, heat treatment is performed while pressing the IC chip 6 toward the wiring board 4 side, and the thermosetting adhesive 2 is hardened to integrally bond the IC chip 6 to the wiring board 4 and to wire via the conductive particles 1. The wiring pattern of the substrate 4 and the protruding electrodes 7 of the IC chip 6 are electrically connected. Also,
In such a method, an external connection terminal of an electronic component such as a tape carrier package (TCP) on which a semiconductor chip is mounted and a wiring pattern of a wiring board are connected via an anisotropic conductive adhesive, and a tape is used. It is also used when integrally bonding a carrier package and a wiring board.

[0003]

However, in such a conventional joining method, since the anisotropic conductive adhesive 3 is a mixture of the thermosetting adhesive 2 and the conductive particles 1, the anisotropic bonding adhesive 3 is used for joining. Once adhered, the adhesive strength becomes large, and therefore, when the IC chip 6 malfunctions or the connection fails at the time of bonding, there is a problem that it is difficult to peel the IC chip 6 from the wiring board. . In particular, since the thermosetting adhesive 2 is used, the method of heating (melting) this adhesive cannot be used, and when the IC chip 6 is mechanically peeled off, the IC chip 6 and the wiring may be removed. Board 4
There was a problem to damage. In addition, even if the IC chip 6 can be peeled off by avoiding such damage, as shown in FIG.
As shown in, the thermosetting adhesive 2 and the conductive particles 1 remain on the surface of the wiring pattern 5 and the protruding electrodes 7,
There is a problem that the IC chip 6 and the wiring board 4 cannot be regenerated. The problem to be solved by this invention is
What measures should be taken to obtain a bonding method for electronic components that allows easy replacement of electronic components and reconnection of electronic components when malfunctions or poor connection of electronic components occur and that has a good mounting yield In point.

[0004]

Therefore, the invention according to claim 1 comprises a step of disposing conductive particles having an adhesive layer on the surface thereof, at least on a wiring pattern of a wiring board or a connection portion of an electronic component. A wiring pattern of the wiring board and a connecting portion of the electronic component are superposed on each other via the conductive particles, and heating and pressing are performed to electrically connect the wiring pattern and the connecting portion via the conductive particles. The provision of a temporary joining step of electrically connecting and a main joining step of disposing an insulating resin between the wiring pattern and the connection portion connected via the conductive particles is solved. As a means.

According to the second aspect of the invention, after the temporary joining step is performed and before the main joining step, electrical continuity between the wiring pattern and the connection portion or operation of the electronic component is performed. In the case where a defective product is detected as a result of the inspection, the electronic component is separated from the wiring board, and an inspection repair process is repeated until the temporary bonding process is repeated until a defective product is detected. There is. Further, the invention according to claim is characterized in that the insulating resin is a thermosetting resin and is cured by heating.

Further, the invention according to claim 4 is characterized in that the adhesive layer has thermoplasticity. According to a fifth aspect of the invention, the electronic component is a semiconductor chip. According to a sixth aspect of the invention, the wiring board is a glass substrate of a liquid crystal display device, and the wiring pattern is a transparent wiring. In the invention according to claim 7, when the wiring substrate is a glass substrate of a liquid crystal display device and the wiring pattern is a transparent wiring, the insulating resin is a UV curable resin, It is characterized by being cured by being exposed to UV from the back side.

[0007]

According to the present invention, conductive particles having an adhesive layer on the surface thereof are disposed on at least the wiring pattern of the wiring board or the connection portion of the electronic component, and the connection portion between the wiring pattern of the wiring board and the electronic component is arranged. By overlapping and heating and pressing, the adhesive layer is fluidized and the conductive particles come into direct contact with the wiring pattern and the connecting portion. Further, the fluidized adhesive temporarily bonds the wiring board and the electronic component with the conductive particles in contact with the wiring pattern and the connecting portion. In this state, since the components are temporarily joined, it is possible to perform an inspection as to whether or not the electronic component side and the wiring board side are electrically connected, and an inspection for determining whether or not the electronic component is malfunctioning. . If a defect is found by such an inspection, the electronic component is bonded to the wiring board side only by the thin adhesive layer provided on the surface of the conductive particles, so the adhesive strength is weak and the electronic component is easily Can be peeled off. If a thermoplastic resin is used for this adhesive layer,
By heating, the adhesive fluidizes and the electronic component can be peeled off more easily. Since the adhesive strength of the adhesive layer is weak as described above, it is possible to prevent the electronic component and the wiring board from being damaged due to the peeling of the electronic component.
After the electronic component is peeled off, the amount of the adhesive attached to the wiring pattern and the connection portion is small, so that the electronic component and the wiring board can be easily regenerated. Furthermore, when the wiring substrate is a glass substrate of a liquid crystal display device and the wiring pattern is a transparent substrate, it is possible to cure the insulating resin used in the main bonding step by UV exposure using a UV curable resin by backside exposure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the method for joining electronic components according to the present invention will be described below with reference to the embodiments shown in the drawings. The present embodiment is an example in which the present invention is applied to the case where a semiconductor chip is bonded onto a glass substrate of a liquid crystal display device. First, in this embodiment, I as a wiring pattern as shown in FIG.
The TO wiring 11 is formed on the surface of the wiring board,
A glass substrate 12 of a liquid crystal display device is prepared. Then, as shown in the figure, the conductive particles 13 are dispersed on the surface of the region (including the ITO wiring 11) on the glass substrate 12 where the semiconductor chip is bonded. As shown in FIG. 1, the structure of the conductive particles 13 is such that fine spherical polystyrene particles 14 serving as a core, a nickel (Ni) layer 15 and a gold ( Au) layer 16
And an adhesive layer 17 formed on the surface of the gold layer 16 and made of a thermoplastic resin such as a thin acrylic resin. Further, in order to dispose the conductive particles 13 on the glass substrate 12, it is sufficient to coat the glass substrate 12 with the conductive particles 13 dispersed in a dispersion medium such as methyl alcohol. By evaporation, only the conductive particles 13 are placed on the glass substrate.

Next, as shown in FIG. 3, the semiconductor chip 19 provided with the protruding electrode 18 as a connecting portion is provided in the region of the glass substrate 12 where the conductive particles 13 are arranged, and the protruding electrode 18 and the ITO wiring 11 are formed. Position them so that and are opposite to each other, and overlap them. In this state, the protruding electrode 1
Although a plurality of conductive particles 13 are interposed between the electrode 8 and the ITO wiring 11, no bonding is performed. Then, a thermocompression bonding head (not shown) is applied from the back side of the semiconductor chip 19.
A temporary joining process of pressing and heating and pressing is performed. The heating temperature performed here may be a relatively low temperature at which the adhesive layer 17 is softened because it is thin, and the pressure applied may be low. As a result, as shown in FIG. 4, the adhesive layer 17 of the conductive particles 13 between the protruding electrode 18 and the ITO wiring 11 is crushed. At this time, as shown in FIG. 5, the adhesive layer 17 on the surface of the conductive particles 13 is thermally softened,
It adheres to the protruding electrode 18 and the ITO wiring 11. This adhesion is a weak adhesion because the total adhesion area is extremely small. Therefore, by such a temporary bonding process, the gold layer 16 of the conductive particles 13 is held by the above-mentioned weak adhesive force in a state where the gold layer 16 of the conductive particles 13 is in contact with and electrically connected to the protruding electrode 18 and the ITO wiring 11. .

By thus preliminarily bonding the semiconductor chip 19 to the glass substrate 12, the protruding electrode 18 is provided as an inspection repair process before the main bonding process described later.
It becomes possible to inspect the electrical continuity between the ITO wiring 11 and the ITO wiring 11, and the semiconductor chip 19 is attached to the glass substrate 1.
It is possible to repeat the process of temporary joining again before changing from 2 to a state in which peeling is difficult. That is, in the inspection repair step, when the result of the inspection shows that the protruding electrode 18 and the ITO wiring 11 are not electrically connected to each other, the semiconductor chip 19 is separated from the glass substrate 12 as shown in FIG. The semiconductor chip 19 and the glass substrate 12 are washed with a solvent such as acetone to remove the conductive particles 13. Next, the conductive particles 13 are dispersed and arranged again on the glass substrate 12, and the semiconductor chips 19 are stacked. After that, the semiconductor chip 19 is heated and pressed in the same manner to temporarily bond again.

The conductive particles 13 are attached to the semiconductor chip 19 side and the glass substrate 12 side only by the weak adhesive force of the thermoplastic adhesive as described above. Therefore, as the method for removing the conductive particles 13, a mechanical removal method can be used in addition to the above cleaning. Further, in the temporarily joined state, in addition to the above-mentioned continuity test, the semiconductor chip 19
It is possible to inspect whether there is a malfunction in the liquid crystal display device on the glass substrate 12 side or not. If the presence of defects is detected by these inspections, the semiconductor chip 19 and the glass substrate 12 may be replaced and the temporary bonding process may be performed again.

Next, as shown in FIG. 7, the semiconductor chip 19 is provided for the temporarily bonded product in which no defect is detected through the above-described inspection or the temporarily bonded product in which the defect is eliminated.
The main bonding step of injecting the insulating resin 20 made of a thermosetting resin such as epoxy resin into the gap between the glass substrate 12 and the glass substrate 12 is performed. In this main joining step, the protruding electrode 18 and the ITO that are connected at least through the conductive particles 13 are connected.
An insulating resin 20 is arranged around the wiring 11 and is bonded with sufficient strength. In this way, the electronic components can be joined (mounted) without a conduction failure or the like.

In this embodiment, the semiconductor chip 19 and the glass substrate 12 are temporarily held by the weak adhesive force of the adhesive layer 17 of the conductive particles 13 while obtaining electrical continuity. When the semiconductor chip 19, the liquid crystal display device, or the like is defective, or the connection between the protruding electrode 18 and the ITO wiring 11 is defective, the semiconductor chip 19 can be easily peeled off, and the glass substrate 12 or the semiconductor chip 19 can be easily separated. Playback is possible. For this reason, when a defective electronic component or a defective connection occurs in the temporarily joined state, the electronic component can be easily replaced or the connection can be redone, and the mounting yield can be improved.

In this embodiment, the thermosetting resin is used as the insulating resin in the main joining process, but since the wiring substrate is the glass substrate 12 and the wiring pattern is the ITO wiring 11, the thermosetting resin is used. UV (ultraviolet light) curable resin is used instead of resin, and UV is applied from the lower surface (back surface) side of the glass substrate 12.
Exposure may be performed. As described above, the use of the UV curable resin has an advantage that heating is not required unlike the thermosetting resin.

Although the embodiment has been described above, the present invention is not limited to this, and various design changes accompanying the gist of the configuration can be made. For example, although the glass substrate 12 is used as the wiring substrate in the above embodiment,
Various wiring boards made of other materials can be applied. In the above embodiment, the core material of the conductive particles 13 is the polystyrene particles 14, but any material having appropriate hardness such as phenol resin or acrylic resin may be used. Further, the conductive material layer formed on the surface of the core material is not limited to the nickel layer 15, the gold layer 16 and the like as in the above embodiment. Further, on the surface of the conductive particles 13, an adhesive layer 17 made of a thermoplastic resin such as acrylic is used as an adhesive layer.
However, an adhesive having no thermoplasticity may be used. In short, an adhesive that can temporarily bond the electronic component and the wiring board and that can be easily removed by washing after peeling the electronic component may be used. Further, in the above-mentioned embodiment, the conductive particles 13 are dispersed and arranged on the glass substrate 12,
If the conductive particles 13 can be uniformly arranged, the semiconductor chip 1
Of course, they may be arranged on the 9 side or both sides of the glass substrate 12 and the semiconductor chip 19. Furthermore, in the above embodiment, the semiconductor chip 19 is directly connected to the glass substrate 12, but the present invention is also applied to the case of connecting an external terminal of a tape carrier package (TCP) or an electrode of another electronic component. be able to.

[0016]

As is apparent from the above description, according to the present invention, the electronic component can be easily peeled off when the electronic component malfunctions, the connection is defective, etc., and the wiring board and the electronic component are easily separated. Has the effect of enabling the reproduction of. Further, if the insulating resin for final bonding is, for example, a UV curable resin, there is an advantage that the heating process can be reduced.

[0017]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of conductive particles used in an example of the present invention.

FIG. 2 is a cross-sectional view showing a step of dispersing conductive particles in an example of the present invention.

FIG. 3 is a sectional view showing a state in which a semiconductor chip according to an embodiment of the present invention is placed on a glass substrate.

FIG. 4 is a cross-sectional view showing a temporary joining step in the example of the present invention.

FIG. 5 is a cross-sectional view of essential parts showing a temporarily joined state in the example of the present invention.

FIG. 6 is a cross-sectional view showing a step of peeling a semiconductor chip according to an example of the present invention.

FIG. 7 is a cross-sectional view showing a main joining step in the example of the present invention.

8A and 8B are cross-sectional views showing a conventional joining method.

FIG. 9 is a cross-sectional view showing a problem of the conventional example.

[Explanation of symbols]

 11 ITO Wiring (Wiring Pattern) 12 Glass Substrate (Wiring Substrate) 13 Conductive Particles 15 Nickel Layer 16 Gold Layer 17 Thermoplastic Adhesive 18 Projection Electrode (Connecting Part) 19 Semiconductor Chip (Electronic Component) 20 Insulating Resin

Claims (7)

[Claims] 1. A step of disposing conductive particles having an adhesive layer on a surface thereof at least on a wiring pattern of a wiring board or a connection portion of an electronic component, and a connection portion between the wiring pattern of the wiring substrate and the electronic component. And superimposing via the conductive particles, a temporary bonding step of electrically connecting the wiring pattern and the connection portion through the conductive particles by heating and pressing, and the conductive particles. A main joining step of disposing an insulating resin between the wiring pattern and the connection portion connected via the joining method. 2. After performing the temporary joining step and before the main joining step, electrical continuity between the wiring pattern and the connection portion or an operation of the electronic component is inspected, and a result of the inspection is obtained. The electronic component according to claim 1, further comprising an inspection repair step of peeling the electronic component from the wiring board when a defect is detected and repeating the temporary bonding step again until it is detected as a non-defective product. How to join. 3. The insulating resin is a thermosetting resin,
The method of joining electronic components according to claim 1, wherein the method is a method of curing by heating. 4. The method of joining electronic components according to claim 1, wherein the adhesive layer is made of a thermoplastic resin. 5. The method for joining electronic components according to claim 1, wherein the electronic components are semiconductor chips. 6. The method of joining electronic components according to claim 1, wherein the wiring substrate is a glass substrate of a liquid crystal display device, and the wiring pattern is a transparent wiring. 7. The method for joining electronic components according to claim 6, wherein the insulating resin is a UV curable resin and is cured by being exposed to UV from the back surface side of the glass substrate.