JPH10144725A - Method of mounting integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent short-circuiting of an outer lead due to outflow of an adhesive without controlling the applied amount of the adhesive and a wettable area with high accuracy, by applying the adhesive to a central part of a bonding face of an integrated circuit and a printed circuit board and applying an adhesive having a high insulation performance to the periphery of the central part. SOLUTION: A conductive adhesive 9 is applied to the central part of a connection pattern 3 for connecting a die of an integrated circuit provided on a printed circuit board, that is, the central part of a die outer shape 8 of the integrated circuit. An insulative adhesive 10 is applied around the conductive adhesive 9. For example, a silver paste or the like is used as the conductive adhesive 9 and a silicon adhesive or the like is used as the insulative adhesive 10. When an integrated circuit is mounted, the conductive adhesive 9 wets only within the range sufficiently smaller than the die outer shape 8 of the integrated circuit by a dam effect of the insulative adhesive 10. The back face of the die of the integrated circuit and the connection pattern 3 on the printed circuit can be electrically connected without adhesion of the conductive adhesive 9 to the outer lead.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an integrated circuit, and more particularly to a technique effective when applied to a method for mounting an integrated circuit sealed in a TCP (Tape Carrier Package) on a printed wiring board. Things.

[0002]

2. Description of the Related Art Conventional mounting methods for integrated circuits include, for example, “Electronic mounting technology (1996.5 Vol.
5) ”on pages P31 to P36.

[0005] This mounting method will be described with reference to FIG.

FIG. 5 shows a conventional method of mounting an integrated circuit sealed in TCP on a printed wiring board.
FIG. 3 shows a cross-sectional shape of an adhesive portion between an integrated circuit die and a printed wiring board.

In FIG. 5, 1 is an integrated circuit die, 2 is an adhesive, 3 is a die connection pattern, 4 is a through hole,
Reference numeral 5 denotes a heat radiation piece connection pattern, 6 denotes a heat radiation piece, and 7 denotes an outer lead.

The TCP type integrated circuit shown in FIG. 5 is characterized in that it is lightweight and thin, is often mounted on a notebook computer, and generates a large amount of heat of 5 to 8 W. The die 1 is exposed so that the die 1 is directly connected to a heat radiating member to improve heat conduction.

[0007] The die 1 of the integrated circuit, as shown in FIG.
It is mounted by attaching a conductive adhesive 2 to the back surface and connecting to the pattern 3 on the printed wiring board.

[0008] With this mounting, heat generated from the integrated circuit is radiated from the integrated circuit via the through holes 4 provided in the pattern 3 to the heat radiation pieces 6 attached to the back surface of the printed wiring board.
And the heat is released.

[0009]

The above-mentioned integrated circuit die 1 is bonded to a pattern 3 on a printed wiring board with an adhesive 2 as shown in FIG. The pattern 3 is connected to the pattern 5 provided on the surface opposite to the ground layer and the integrated circuit mounting surface through the through hole 4, and further mounted so that the heat radiation piece 6 is attached to the pattern 5.

In addition, since the back surface of the die 1 of the integrated circuit needs to be at the ground potential in order to satisfy electrical characteristics, in the above-described mounting, the die 1 and the connection pattern 3 on the printed wiring board are conductive. In order to transfer the potential of the connection pattern to the ground potential and to efficiently transmit the heat generated from the integrated circuit to the heat radiating piece, the connection between the back surface of the die 1 and the printed wiring board is required. The bonding area with the application pattern 3 must be maximized.

However, if the bonding area is maximized, the conductive adhesive 2 may protrude beyond the outer shape of the die 1 and spread, resulting in short-circuiting of the outer leads. There was a problem that the wet spread area had to be controlled with high precision.

An object of the present invention is to provide a technique capable of preventing short-circuiting of an outer lead due to the protrusion of an adhesive without controlling the amount of adhesive applied and the spread area of the adhesive with high precision. .

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0014]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

[0015] A highly conductive adhesive is applied to the central portion of the adhesive surface between the integrated circuit and the printed wiring board, and a highly insulating adhesive is applied to a peripheral portion of the adhesive surface surrounding the central portion. Is mounted on a printed wiring board.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for mounting an integrated circuit according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the application of an adhesive on a printed circuit board on which an integrated circuit is mounted. FIG.
In the figure, 8 indicates an outer shape of a die of an integrated circuit, 9 indicates a conductive adhesive, and 10 indicates an insulating adhesive.

As shown in FIG. 1, the integrated circuit according to the present embodiment is mounted on a central portion of a connection pattern 3 for connecting an integrated circuit die provided on a printed wiring board, that is, an integrated circuit die. A conductive adhesive 9 is applied to a central portion of the outer shape 8, and an insulating adhesive 1 is further provided around the conductive adhesive 9.
0 is applied. The conductive adhesive 9 described above may be an adhesive having high conductivity, and for example, a silver paste or the like is used. The insulating adhesive 10 may be an adhesive having high insulating properties and high thermal conductivity. For example, a silicon-based adhesive or the like is used.

After that, when the integrated circuit is mounted, as shown in FIG.
Are spread and wet between the die 1 of the integrated circuit and the connection pattern 3 on the printed wiring board.

FIG. 3 shows the cross-sectional shape of the bonding portion between the die 1 of the integrated circuit and the printed circuit board. As shown in FIGS. 2 and 3, the conductive adhesive 9 wets and spreads only in a range sufficiently smaller than the die outer shape 8 of the integrated circuit due to the dam effect of the insulating adhesive 10 and is integrated without adhering to the outer leads 7. It is possible to electrically connect the back surface of the die of the circuit and the connection pattern 3 on the printed wiring board.

The insulating adhesive 10 applied around the conductive adhesive 9 is insulative and does not short-circuit even if it adheres to the outer leads. The amount can be applied.

Further, since the above-mentioned conductive adhesive 9 and insulating adhesive 10 are adhesives composed of different components, a uniform adhesive layer may not be obtained due to their respective viscosities. .

In such a case, as shown in FIG. 4, the through hole 4a in the center portion (the diameter of the portion to which the conductive adhesive 9 is applied and the through hole 4b in the peripheral portion (the insulating adhesive 10 A uniform adhesive layer can be obtained by changing the size of the diameter of the portion to be applied) according to the respective viscosities.

For example, when the insulating adhesive 10 applied to the periphery of the integrated circuit die 1 is more likely to flow out to the back surface of the printed wiring board through the through hole than the conductive adhesive 9 applied to the central portion of the die 1 of the integrated circuit. In the figure, only the central portion has the back surface of the integrated circuit die 1 and the connection pattern 3 on the printed wiring board.
Since an adhesive layer is formed in between and the adhesion of the peripheral portion is incomplete, as shown in FIG.
Is smaller than the diameter of the through hole 4a at the center. Thereby, it is possible to obtain a uniform adhesive layer.

As shown in FIG. 4, by increasing the diameter of the through hole 4a (the portion to which the conductive adhesive 9 is applied) at the center, the connection area of the conductive adhesive 9 can be increased. And the conductivity can be improved.

In addition to the above-described mounting using two types of adhesives, the die 1 of the integrated circuit and the pattern on the printed wiring board are connected by a conductive and good heat conductive adhesive sheet. Similarly, short-circuiting of the outer lead can be prevented.

Therefore, as described above, a conductive adhesive is applied to the central portion of the bonding surface between the integrated circuit and the printed wiring board, and an insulating adhesive is applied to the peripheral portion of the bonding surface surrounding the central portion. However, by mounting the integrated circuit on the printed wiring board, the insulating adhesive becomes a dam, and the conductive adhesive does not protrude to the outer lead side and does not spread. Without performing the control with high precision, it is possible to prevent the outer leads from being short-circuited due to the protrusion of the adhesive.

As described above, the invention made by the present inventor is:
Although specifically described based on the embodiment, the present invention
It is needless to say that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the scope of the invention.

[0029]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

It is possible to prevent the outer leads from being short-circuited due to the protrusion of the adhesive without controlling the amount of the adhesive applied and the wet spread area with high precision.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining application of an adhesive in a method of mounting an integrated circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a shape of an adhesive portion between a die 1 of an integrated circuit and a printed board.

FIG. 3 is a diagram illustrating a cross-sectional shape of an adhesive portion between a die of an integrated circuit and a printed circuit board.

FIG. 4 is a diagram showing a printed wiring board in which the diameters of through holes in the central part and the peripheral part of the bonding surface between the die of the integrated circuit and the printed board are changed.

FIG. 5 is a view for explaining a conventional method of mounting an integrated circuit sealed in TCP on a printed wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Die of integrated circuit, 2 ... Adhesive, 3 ... Die connection pattern, 4, 4a, 4b ... Through hole, 5 ... Heat dissipation piece connection pattern, 6 ... Heat dissipation piece, 7 ... Outer lead, 8 ... Integrated circuit Die outer shape, 9: conductive adhesive, 10: insulating adhesive.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideaki Mizuno 1 Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Pref. Information Equipment Division, Hitachi, Ltd.

Claims (2)

[Claims] 1. An integrated circuit mounting method for applying an adhesive to an integrated circuit and mounting the integrated circuit on a printed wiring board, wherein a highly conductive adhesive is applied to a central portion of a bonding surface between the integrated circuit and the printed wiring board. A method for mounting an integrated circuit, comprising applying a highly insulating adhesive to an outer portion of an adhesive surface surrounding a central portion thereof, and mounting the integrated circuit on a printed wiring board. 2. The method of mounting an integrated circuit according to claim 1, wherein a diameter of a through hole arranged in a pattern on the printed wiring board is determined by a central portion and a peripheral portion of a bonding surface with the integrated circuit. A method of mounting an integrated circuit, wherein the integrated circuit is mounted on the printed circuit board with different sizes.