JPH0433137B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a high-density integrated circuit package, and in particular, a multi-chip integrated circuit that can mount a plurality of LSI chips at high density and has good heat dissipation characteristics. It is related to package.

[Conventional technology]

Computers in recent years have undergone significant improvements toward higher performance and higher density. This is largely due to advances in high-density technology for IC chips, with the density of high-speed logic IC chips ranging from a few hundred gates/chip a few years ago to 100 to 2000 gates/chip in recent years. It has even come to be put into practical use.

The high integration of IC chips has led to the development of microfabrication technology that allows active and passive devices to be formed at high density on a silicon substrate and to connect these devices with fine wiring, as well as improvements in the formation process of these devices. This can be said to have been achieved by reducing power consumption per gate through improved technology. however,
With the realization of such high integration, high-speed logic ICs
The power consumption per chip is on the rise compared to the past. The reason for this is that with the increasing density of gate circuits, design engineers naturally want to minimize the signal propagation speed and drive energy consumed by wiring by shortening the length of connection wiring between gate circuits as much as possible. As a result of this attempt, as many gate circuits as possible were packed into one chip, the total power consumption per chip actually increased compared to the conventional one. Therefore, in the package structure in which these IC chips are mounted, an important technical issue is how to effectively dissipate the heat generated by the high-power IC chips. An example of such technology is US Pat.
(No.). That is, as shown in FIG. 1 of this document, this method efficiently transmits the heat generated by the IC chip 16 to the heat sink 42 through the preform 14 made of fiber glass and thermosetting plastic resin and dissipates it.

[Problem that the invention seeks to solve]

However, the thermal conductivity properties of such plastic resins are on the order of 0.005 W/inch·°C, which is an order of magnitude worse than that of inorganic materials. For example, the thermal conductivity of metal oxides such as alumina is on the order of 0.7 W/in.°C, and that of metals such as copper.
It is on the order of 10W/inch・℃. Furthermore, as shown in Figure 1 of the above cited document, in order to secure the IC chip 16 to the substrate 12 and at the same time dissipate heat, a polymer material with high insulation properties and ability to absorb mechanical stress is used. seems to be doing so. However, in such a structure, the limit of the IC chip's cooling capacity is determined by the thermal conductivity properties of the plastic resin, making it difficult to mount IC chips that consume higher power or generate more heat. Become.

An object of the present invention is to minimize the thermal resistance of the heat dissipation path between the IC chip and the heat sink.
By directly fixing the IC chip to the heat sink using a highly thermally conductive adhesive, we can improve the thermal conductivity from the IC chip to the heat sink, and also improve the thermal conductivity between the wiring board on which the IC chip is mounted and the heat sink. It is an object of the present invention to provide a multi-chip integrated circuit package that can also alleviate mechanical stress caused by thermal expansion and contraction caused by temperature differences.

[Means for solving problems]

The multichip integrated circuit package of the present invention comprises:
The device includes a wiring board, a plurality of IC chips lead-connected to the wiring board, a heat radiation cover attached to the wiring board so as to cover these IC chips, and a heat sink attached to the heat radiation cover. An elastic resin material is inserted between each of the IC chips and the wiring board, and each of the main bodies of the plurality of IC chips has a thermally conductive material on the inner surface of the heat dissipation cover. It has a structure in which die bonding is performed all at once using die adhesive.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1 showing an embodiment of the present invention, 1 is a wiring board, 2 is an IC chip, 3 is a die adhesive, 4 is a heat dissipation cover, 5 is a heat sink, 6 is an IC lead,
7 is a bonding pad, 8 is an input/output terminal, and 9 is a silicon rubber.

Figure 2 shows the tape automated version of Figure 1.
The circuit surface of the IC chip 2 of the tape automated bonding (hereinafter abbreviated as TAB) type is shown, and FIG. 3 shows the circuit surface of the TAB IC chip 2.
FIG. 4 shows the state in which the TAB IC chip 2 is mounted.

Referring to FIGS. 1 to 4, the wiring board 1 is, for example, Proceedings 1980 30th Electronic
A on Components Conference p283-p285
Multi-Layer Ceramic, Multi-Chip Module
On page 284 of the paper published under the title
MULTI−LAYER CERAMIC
It is a laminated ceramic board made by laminating and firing alumina green sheets as explained under the title TECHNOLOGY, and the input/output terminal 8 is used for testing the board as shown in FIGURE 5 on page 284 of the same document. SUBSTRATE
ELECT.TEST) is brazed (PIN BRAZE).

IC chip 2 has silicon rubber 9 on its circuit surface.
It is fixed to the surface of the substrate 1 by sandwiching the . The main reason why the silicone rubber 9 is used is that its elasticity cushions the stress applied to the IC chip 2 in the pressing direction.
It is also used to fix the IC chip 2 when the leads 6 of the IC chip 2 are bonded to the substrate 1a.

The heat dissipation cover 4 is attached to the substrate 1 so that the dies of the plurality of IC chips 2 on the substrate 1 are adhered to the inside thereof. A die adhesive 3 is used to bond each IC chip 2 to the heat dissipation cover 4. The die adhesive 3 preferably has as good a thermal conductivity as possible, and tin-lead eutectic solder is used in the embodiment of the present invention.

The heat sink 5 is glued onto the heat dissipation cover 4.
The heat generated by the IC chip 2 is efficiently dissipated.

As explained above, the present invention includes a wiring board 1,
It is composed of TAB IC chip 2, silicone rubber 9, die adhesive 3, heat dissipation cover 4, and heat sink 5, and provides a multi-chip integrated circuit package with good heat dissipation characteristics. In order to achieve this, each of the components constituting the above-mentioned present invention plays an extremely important role. The role thereof and the good heat dissipation characteristics obtained thereby will be explained in detail below.

In order to obtain good heat dissipation characteristics, IC chip 2
In the heat conduction path from to the heat sink 5,
It goes without saying that it is desirable to use a material with as good a thermal conductivity as possible and to avoid a structure that would impair the thermal conductivity.

On the other hand, especially in the multi-chip package structure of the present invention, in order to mount IC chips at high density on a wiring board, it is better to mount a heat sink all at once than to mount each IC chip individually. It is also clear that it is preferable. Each element constituting the present invention has been optimally selected to satisfy the above-mentioned requirements and realize excellent heat conduction characteristics.

That is, the heat dissipation cover 4 is attached to the wiring board 1 so as to cover all the IC chips 2 on the wiring board 1, and the die of each IC chip 2 is fixed inside with the die adhesive 3. However, in this case, it is necessary to uniformly adhere a plurality of IC chips arranged on the substrate 1 with slightly varying heights to the inner surface of the heat dissipation cover 4. This is because if even one IC is not sufficiently bonded to the heat dissipation cover, a sufficient heat path will not be formed, and heat dissipation from that chip will be insufficient.

Silicone rubber 9 is used to solve this problem. That is, as shown in FIG. 4, the silicone rubber 9 is sandwiched between the IC chip 2 and the substrate 1, and its elasticity prevents the IC chip from being excessively pressed by the heat dissipation cover 4 during die bonding. This prevents the IC chip from being destroyed due to excessive stress. Therefore, as mentioned above, the heat dissipation cover 4
By applying a certain amount of pressure to press down the IC chips 2 when attaching the board, all the IC chips on the board can be brought into uniform contact with the inner surface of the heat dissipation cover and bonded.

The well-known TAB chip is used as the IC chip 2. As shown in FIGS. 2 and 3, the TAB chip has a structure in which a tape-shaped lead 6 is attached to the IC chip alone. Therefore, when performing lead bonding on the substrate 1, the third
As shown in the figure, if the leads 6 are bent and shaped, they can follow the vertical movement of the IC chip body without causing lead breakage.
Even if the chip is pressed down, there will be no disconnection between it and the bonding pad 7 on the substrate 1 to which the leads are bonded.

As mentioned above, a metal adhesive with good thermal conductivity is used as the die adhesive to form a good heat conductive path between the IC chip 2 and the heat dissipation cover 4.

Another advantage of using a TAB chip for the IC chip 2 is that the heat dissipation cover 4 and the wiring board have different amounts of thermal expansion due to the temperature difference between the two, and as a result, the leads 6 of the IC chip 2 are resistant to stress.
That is, since the main body of the IC chip 2 is bonded to the heat dissipation cover 4, the temperature rises due to the heat generated by the IC chip.
Since only the ICs are bonded together, the temperature does not rise. Therefore, even if the heat dissipation cover 4 and the substrate 1 are made of the same material, the amount of thermal expansion will be different for each IC.
Chip 2 mainly causes lateral displacement,
If the IC lead 6 is bent and shaped as shown in FIG. 3, the lead will not be disconnected from the bonding pad 7 on the substrate even if the IC lead 6 is misaligned to the extent described above.

This suggests that by further adjusting the amount of lead shaping, it is possible to follow even a considerable degree of positional deviation, and therefore, when selecting the material for the heat dissipation cover 4, it is possible to pursue a material with better thermal conductivity. It gives us possibilities.

〔Effect of the invention〕

As explained above, the present invention provides a multi-chip integrated circuit package with extremely good heat dissipation characteristics and high density by using a structure consisting of a TAB IC chip, silicone rubber, metallic die adhesive, and a heat dissipation cover. This has the effect of realizing a multi-chip integrated circuit package.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
3 are a plan view and a front view showing details of the IC chip shown in FIG. 1, and FIG. 4 is a perspective view showing details of the IC chip shown in FIG. 1 in a mounted state. 1...Wiring board, 2...TAB IC chip, 3...
...Die adhesive, 4...Radiation cover, 5...Heat sink, 9...Silicone rubber.

Claims (1)

[Claims] 1. A wiring board, a plurality of tape automated bonding type IC chips that are lead-connected face-down on the wiring board, and a plurality of tape automated bonding type IC chips that are connected to the wiring board in a face-down state, and a plurality of IC chips that are placed on the wiring board so as to cover the plurality of IC chips. a heat dissipation cover attached to the heat dissipation cover; and a heat sink fixed on the heat dissipation cover;
An elastic resin material is inserted between the IC chip and the wiring board, and the plurality of IC chip bodies are collectively attached to the inside of the heat dissipation cover using a die adhesive having good thermal conductivity. A multi-chip integrated circuit package characterized by die bonding.