JPS6118864B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an IC chip mounting structure.

In recent years, with the shift to LSI and higher density packaging of IC chips, there has been an increasing need for lower thermal resistance in IC chip packaging. However, in the conventional IC chip mounting structure, in which the IC chip is mounted face-up, the mounting board has both wiring and heat dissipation functions, so the degree of heat dissipation from the IC chip depends on the thermal conductivity of the board material. Therefore, it was difficult to reduce the thermal resistance.

The present invention provides an IC that eliminates the drawbacks of the conventional methods described above.
The purpose is to provide a chip mounting structure.

The IC chip mounting structure of the present invention is characterized in that in face-up mounting of an IC chip, heat dissipation of the IC chip is performed directly from the back surface of the IC chip without passing through the mounting board.

FIG. 1 is a perspective view showing a board for mounting an IC chip. In FIG. 1, a substrate 1 has a cavity 3 through which an opening 2 passes, and around the opening 2, a resin adhesive such as epoxy resin or silicone resin or a bonding agent 4 such as solder is applied for fixing an IC chip. be. A pattern 5 is also formed on the board for connection to the connection pad of the IC chip.

FIG. 2 is a perspective view showing a first embodiment of the invention. In FIG. 2, a substrate 1 is placed on a fluid 6 with good thermal conductivity such as water or a liquid metal such as Freon, and an IC chip 7 fixed with a bonding agent 4 is mounted on the substrate 1. . The connection pad 8 of the IC chip 7 and the pattern 5 are connected by a wire 9. FIG. 3 is a sectional view taken along line A-A' in FIG.
In FIG. 3, an IC chip 7 is fixed to a substrate 1 with a bonding agent 4, and a fluid 6 with good thermal conductivity such as water, a liquid such as Freon, or a liquid metal is directly applied through a cavity 3 of the substrate 1. Since it is in contact with the back surface of the IC chip, heat dissipation from the IC chip 7 is effectively performed.

The effectiveness of heat dissipation by this mounting method is demonstrated by the fact that there is no cavity on the board and the entire back surface of the IC chip is made of ceramic.
Or compare it with a mounting method that is bonded to an epoxy resin board. For example, if the IC chip size is 2 □mm, and the thermal resistance of the bonding agent used to bond the IC chip and the board is not taken into account, the heat dissipated from the IC chip is absorbed into the board through the back surface of the IC chip.
Assuming that it spreads at a 45° angle, the thermal resistance of the alumina substrate is 3.3°C/W. Thermal resistance is 1.0 when an epoxy resin substrate is used instead of an alumina substrate.
×10 ³ ℃/W. On the other hand, if a liquid such as water or Freon is poured under the board, the above will generally occur.
It can be considered that the thermal resistance has disappeared by the amount of thermal resistance of the substrate below the IC chip, and the thermal resistance will decrease.

FIG. 4 is a sectional view showing the second embodiment. In FIG. 4, the cavity of the substrate is diagonally opened. The shape of the cavity can thus take various shapes.

FIG. 5 is a perspective view showing an embodiment in which a board on which a large number of IC chips are mounted as shown in FIG. 2 is mounted for cooling. In FIG. 5, two substrates on which IC chips 7 are mounted are mounted on a cylinder 10. As shown in FIG. The tube 10 contains a liquid such as water or Freon, or a fluid with good thermal conductivity such as a liquid metal, and the heat is cooled through a heat exchanger 11 as indicated by the arrow 1.
The fluid circulates in two directions.

FIG. 6 is a cross-sectional view of the state shown in FIG. 5 when the substrate 1 is attached to the board 13 with the connector 14 for electrical connection between the substrates 1. In Figure 6
It can be seen that the back surface of the IC chip 7 is in direct contact with a liquid such as water, Freon, or a liquid 6 with good thermal conductivity such as liquid metal.

The IC chip mounting structure of the present invention achieves low heat and resistance, and can be particularly effectively applied to mounting highly integrated, high power IC chips.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the IC chip mounting board, Figure 2
The figure is a perspective view showing the first embodiment of the present invention, FIG. 3 is a sectional view taken along the line A-A' of FIG. 2, and FIG. 4 is a sectional view showing the second embodiment of the invention. , FIG. 5 is a perspective view of a mounting for cooling a board according to the present invention, and FIG. 6 is a sectional view of the mounting with the board and connector added to FIG. 5. In the figure, 1...substrate, 2...opening, 3
...Cavity, 4...Binding agent, 5...Pattern, 6...
...Liquid such as water or Freon, or fluid with good thermal conductivity such as liquid metal, 7...IC chip, 8...Connection pad, 9...Wire, 10...Cylinder, 11...Heat exchanger, 12 ...Arrow, 13...Board, 14...
...Indicates each connector.

Claims (1)

[Claims] 1. A mounting board having a cavity through which an opening smaller than the outer dimensions of the rear surface of the IC chip passes through the IC chip mounting surface; a bonding agent for fixing the IC chip to the mounting board;
An IC chip mounting structure characterized by comprising means for bringing a fluid with good thermal conductivity into contact with the back surface of the IC chip.