JPH09191029A - Method of repairing chip and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable improving the manufacturing yield of a circuit mounting board by a method wherein solvent is selectively supplied only to a part of defective connection or a defective LSI chip, only the part is selectively heated, bonding strength between the LSI chip and a board is decreased, and the LSI chip is peeled. SOLUTION: Solvent is selectively supplied only to the part of defective connection or defective LSI chip 8 of a circuit mounting board 7 wherein the LSI chip is mounted on a circuit board with an anisotropical conductive film by a flip-chip bonding method. Only the part to which the solvent is supplied is selectively heated, bonding strength between the LSI chip 8 and the board is decreased, and the LSI chip 8 is removed. For example, a cylindrical jig 9 formed of steel plate of 0.3mm in thickness is fixed on an LSI chip mounting part of the LSI chip mounting glass circuit board 7, with a double-sided adhesive tape. Dimethyl formamide is injected in the cylindrical jig 9 up to about 70% of it. The cylindrical jig 9 is set on a partially heating stage, capped in the state that slight gap is formed, and heated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device repair method.

[0002]

2. Description of the Related Art A bare LSI chip is mounted on a substrate by a chip-on-glass method (hereinafter abbreviated as COG method) using an anisotropic conductive film (hereinafter abbreviated as ACF). Is a promising method to realize. However, when mounted by this method, if there is a mounting defect such as a positional deviation during mounting, or an LSI chip defect,
Although there is a problem that the whole circuit mounting board becomes defective and the yield is reduced, there is no effective means for solving this.

[0003]

One of the major practical problems of the mounting method in which a bare LSI chip is mounted on a substrate by using the ACF in the COG method is to improve the manufacturing yield.
For example, when a driving IC for a liquid crystal display element (hereinafter abbreviated as LCD) is directly COG mounted on a panel, 10 or more ICs are mounted on one panel. Therefore, the probability of requiring repair is high. Since a large amount of cost is required for the COG mounting process of an IC, discarding the entire panel due to only one IC defect causes a large cost increase. However, in the past, I implemented COG using ACF.
C had a problem that it could not be peeled off.

[0004]

In order to solve the above problems, the present invention has devised the following method.

(1) An LSI chip is used for CO
The G-mounted circuit mounting board is inspected after mounting, and the defective LSI chip connection portion is specified.

(2) Only the ACFs of the defective chip portion and the defective mounting portion are swollen with a solvent to reduce the adhesive force between the LSI chip and the substrate. As a result, the LSI chip can be easily peeled off.

(3) After peeling off the LSI chip, the adhesive agent of the ACF remaining on the connection portion is removed.

(4) A new chip is mounted.

Hereinafter, the present invention will be described in detail.

The COG mounting process of the LSI chip by ACF is as follows.

(1) ACF is attached to the connection terminal portion of the circuit board.

(2) After the bumps of the LSI chip and the connection terminals of the circuit board are aligned with each other, they are heat-pressed.

ACF is a film in which conductive particles 2 are dispersed in an uncured binder resin 1 (FIG. 1). The board and components are connected by thermocompression. As shown in FIG. 2, the connection structure using the ACF includes the connection terminals 5 of the substrate 6 and
The structure is such that the connection terminals 4 of the component 3 are electrically connected by conductive particles. Since there is no conductivity in the in-plane direction of the film, insulation can be secured between adjacent terminals. As the conductive particles, metal particles having a diameter of 5 to 20 μm or those obtained by plating a metal on a plastic surface are generally used. An epoxy resin is generally used as the binder resin.

Since epoxy resin has a strong adhesive force,
Once bonded, it cannot be easily peeled off. Although this property is advantageous for connection reliability, it cannot be repaired even if it is found to be defective after mounting, and it must be discarded.

The present invention provides a method for repairing an LSI chip bonded with an epoxy resin or the like having a strong adhesive strength as described above, and a specific method will be described below.

Since a thermosetting resin such as an epoxy resin is a polymer having a three-dimensional network structure formed therein, it does not become so soft even when heated, and peeling by heating is difficult. Further, since it is insoluble in any solvent, it is impossible to dissolve the binder resin in the solvent. However, LSI
It is not always necessary to dissolve the epoxy resin in a solvent in order to peel off the chip, and it may be possible to achieve the purpose by swelling the epoxy resin with the solvent and reducing the adhesive force between the substrate and the LSI chip. The present invention was devised based on the concept of.

On the other hand, many components are mounted on the circuit board at locations other than the connection portion to be repaired. Therefore, if the entire circuit board is dipped in a heated solvent in order to swell the epoxy resin of the ACF of the connection part to be repaired, there is a problem that parts other than the repair part and the connection member are affected.

The present invention has devised a method of supplying heated solvent only to the connection to be repaired. That is, as shown in FIG. 3, a heat-resistant tubular jig 9 is fixed so as to surround the chip 8 to be peeled off of the circuit mounting board 7, a solvent is poured into the tubular jig, and then this Set on a stage that can be locally heated, and for a predetermined time, preferably 1 to 10
Heat for a minute. By this method, the heated solvent can be selectively supplied only to the connection portion to be repaired without damaging the portion other than the connection portion to be repaired on the circuit board.

When a thermosetting adhesive, an instant adhesive or the like is used as a method for fixing the cylindrical jig for locally supplying the solvent, there are the following problems.

(1) It takes time to cure the adhesive (especially in the case of a thermosetting adhesive).

(2) When the adhesive is applied, the adhesive flows into a place other than the place to be repaired (especially in the case of an instant adhesive).

(3) It takes time to remove the adhesive (especially in the case of an instant adhesive).

Then, as a result of various studies on other methods for fixing the cylindrical jig for locally supplying the solvent, it was found that the fixing with the double-sided tape is the most suitable and achieves the purpose. That is, when the double-sided tape is used, the attaching work is short, and the double-sided tape can be removed together with the jig when removing the tubular jig, so that it takes time to remove like an adhesive. There is no need. Moreover, since the double-sided tape is a solid material, it does not flow into other parts like an adhesive. Further, a slight gap between the substrate and the jig has a self-sealing effect that is closed by the swelling of the double-sided tape, so that it also has excellent solvent retention.

The solvent used is preferably a donor solvent such as dimethylsulfoxide, dimethylformamide, dimethylacetamide, which has an affinity for the epoxy resin and has a relatively high boiling point. A non-polar aromatic solvent such as toluene or xylene can be used, but it has a drawback that it takes time until peeling is possible because the temperature cannot be raised because of its low boiling point. Also, a high boiling point ketone solvent can be used. However, peeling is difficult with an alcohol solvent.

By using the tubular jig of the present invention, the solvent is selectively locally supplied only to the connection portion to be repaired, and the LS is not damaged to the portion other than the connection portion.
The I-chip can be peeled off. In addition, by fixing the tubular jig with double-sided tape, the solvent does not leak, and compared with the method of fixing the tubular jig with a thermosetting adhesive or an instant adhesive, the tubular jig is It takes only a short time to fix. Further, since the liquid adhesive has fluidity, it has an influence on the peripheral portion, but when the double-sided tape is used, there is no influence.

Further, by using the local heating stage of the present invention, it is possible to minimize the thermal influence on the portion other than the connection portion to be repaired on the circuit board.

As a solvent for swelling the binder resin of ACF, dimethyl sulfoxide, dimethylformamide,
Dimethylacetamide is preferred. These solvents have a characteristic that they can be heated to a high temperature because they have high penetrability into resins and relatively high boiling points.

The temperature of the solvent is preferably 5 to 10 degrees lower than the boiling point. When the temperature is high, boiling occurs and the solvent spills from the jig. Further, when the temperature is low, it takes time for the epoxy resin to swell. A heating time of 1 to 2 minutes is sufficient under the above conditions.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to embodiments.

[Example 1] The members used are described below.

Glass circuit board: IT as a connecting terminal material
A substrate on which O was formed was used.

LSI chip: The size is 2.0 × 17.
A chip of 4 mm with gold-plated bumps formed on the connection terminals was used. .

ACF: The thickness of ACF is 25 μm
And A thermosetting epoxy resin was used as the binder resin. As the conductive particles, particles having a diameter of 5 μm formed by forming a gold plating film on plastic were used. The number of conductive particles is 1 m
The number was set to 20,000 per m.

The size of the connecting portions was 45 × 120 μm, and the pitch was 70 μm.

Using the above members, an LSI chip was mounted on a glass circuit board by ACF by the FCA method. An automatic loading machine was used for loading. The pressure, heating temperature, and heating time were 10 MPa, 200 ° C., and 30 s, respectively.

The peeling method of the LSI chip will be described below.

External length 24. made of a 0.3 mm thick copper plate
A cylindrical jig having a size of 0 mm, an outer width of 3.5 mm and a height of 8.0 mm was fixed to the LSI chip mounting portion of the previously manufactured LSI chip mounting glass circuit board with a double-sided tape. Dimethylformamide was injected into the cylindrical jig for about 7 minutes. A local heating stage (surface temperature of 19
(0 ° C.) and then covered with a slight gap. After 1 minute, the temperature of the solvent became 145 ° C. Two minutes after the setting, the substrate was removed from the local heating stage, the lid was removed, the dimethylformamide in the tubular jig was sucked out with a pipette, and then the tubular jig and the double-sided tape were removed.
In this state, the LSI chip is in an adhesive state that can be removed with tweezers, so the LSI chip was removed with tweezers. At this time, most of the binder resin of ACF was on the LSI chip, but it was slightly left on the substrate. After the dimethylformamide remaining on the substrate was wiped off with a cotton swab, the binder resin remaining on the substrate was scraped off with a cotton swab impregnated with acetone. In this state, no binder resin remains on the ITO film, which is the connection terminal of the circuit board.

Next, using the same member as described above, a new LSI chip was mounted on the glass circuit board by the ACF by the COG method. The mounting machine and mounting conditions were the same as the initial LSI chip mounting conditions. Finally, this circuit mounting board was tested to confirm that the newly mounted LSI chip was mounted and connected normally.

[Embodiment 2] By the same method as that described in Embodiment 1, an LSI chip was mounted on a glass circuit board by ACF by the FCA method. Next, made of stainless steel with a thickness of 0.2 mm, external length 24.0 mm, external width 3.5
mm, height 8.0 mm, cylindrical LS
It was fixed to the LSI chip mounting portion of the I-chip mounted glass circuit board with an instant adhesive. Dimethylacetamide was injected into the cylindrical jig for about 7 minutes. This was heated in the same manner as in Example 1. The surface temperature of the heater of the local heating stage is 20
The temperature was 0 ° C., the temperature of the solvent was 160 ° C., and the heating time was 2 minutes.
After the dimethylacetamide in the cylindrical jig was sucked out with a pipette, the cylindrical jig was removed and the LSI chip was removed with tweezers. After the dimethylacetamide remaining on the substrate was wiped off with a cotton swab, the binder resin and the instant adhesive remaining on the substrate were scraped off with a cotton swab impregnated with acetone.
In this state, no binder resin remains on the ITO film, which is the connection terminal of the circuit board.

Then, similarly to Example 1, an LSI chip was newly mounted on the glass circuit board. Finally, this circuit mounting board was tested to confirm that the newly mounted LSI chip was mounted and connected normally.

[0041]

According to the present invention, it is possible to improve the manufacturing yield of circuit mounting boards.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an ACF.

FIG. 2 is an explanatory view showing a connection structure connected by an ACF.

FIG. 3 is an explanatory diagram showing a method of locally supplying a solvent.

FIG. 4 is a perspective view showing the shape of a cylindrical jig for locally supplying a solvent.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Binder resin, 2 ... Conductive particle, 3 ... Connection part, 4 ... Connection part of connection part, 5 ... Board connection terminal, 6 ... Board, 7 ... Circuit mounting board, 8 ... IC chip to be peeled, 9 … Cylindrical jig.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyuki Tsujida 3300 Hayano, Mobara-shi, Chiba Hitachi Ltd. Electronic Devices Division

Claims (5)

[Claims] 1. A solvent is supplied to a circuit mounting board in which an LSI chip is mounted on a circuit board by an anisotropic conductive film by a flip chip attach method, selectively supplying only a defective connection or defective LSI chip portion. L is characterized in that the adhesive force between the LSI chip and the substrate is reduced and the chip is peeled off by selectively heating only the affected portion.
SI chip peeling method. 2. The LSI chip peeling method according to claim 1, wherein the solvent is a solvent selected from dimethyl sulfoxide, dimethylformamide, and dimethylacetamide. 3. A double-sided tape is used to fix a tubular jig to the circuit board, and the solvent is supplied into the tubular jig so that the solvent can be selectively applied only to a defective connection or a defective LSI chip. The LSI chip peeling method according to claim 1, wherein 4. An LS having a defective connection or a defective LSI chip.
A method for repairing an LSI chip, characterized in that an I chip is peeled off and an LSI chip is newly mounted. 5. An LSI according to claim 1, 2, 3 or 4.
Circuit mounting board with a chip repaired.