JPS634714B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel structure of a package for an integrated circuit (hereinafter abbreviated as IC) with low thermal resistance.

In recent years, ICs have become more and more densely packed, and along with this, their heat output has naturally increased. This heat generation, or temperature rise, in an IC is even more noticeable in large-scale integrated circuits (LSI), and when such a temperature rise is accompanied, firstly, the operating point of the active elements in the IC shifts, and secondly, the operating point of the active element in the IC shifts.
This not only causes inconveniences such as a decrease in logic operation speed and thirdly a deterioration of the S/N ratio and a reduction in the so-called noise margin.
Fourth, problems arise when the lifespan of an IC is shortened, and for this reason, how to dissipate heat from the IC, or in other words, maintain low temperatures, is currently becoming an important issue.

FIG. 1 is a side sectional view of a conventional IC, in which a semiconductor chip 2 in which, for example, a logic circuit or the like is incorporated is located near the center of a recess, usually called a cavity, dug into an insulating stem member 1. installed in
The bonding pad (not shown) on the semiconductor chip 2 is connected to the external lead-out terminal 5 using a bonding wire 3 such as a gold wire, so-called wire bonding. It was still insufficient. However, what is shown as 4 in FIG. 1 is a sealing cap that covers the top of the IC.

The present invention has been made in view of these points, and a predetermined portion of the sealing cap 4 is formed into a concave shape when viewed from above, and is brought into thermal contact with the upper surface 2a of the semiconductor chip 2. This is intended to serve as a kind of heat sink, thereby suppressing the temperature rise of the semiconductor chip 2, and will be described in detail with reference to FIG. 2 and subsequent drawings.

FIG. 2 shows a side cross-sectional view of an IC package according to the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. The difference between the package shown in FIG. 2 and the package shown in FIG. 1 is that the sealing cap 4 is provided with a concave portion 8 just above the semiconductor chip when viewed from the top of the package. and the lower surface of the concave portion has a cushioning property,
It is in thermal contact with the upper surface of the semiconductor chip via a layer 9 of an insulating material with low thermal resistance, such as polyimide resin.

The bottom surface of the concave portion of the sealing cap described above is pressed against the top surface of the semiconductor chip 2 by the elasticity of the cap, but in this case, the top surface of the semiconductor chip 2 is usually protected with a thick layer of PSG (phosphosilicate glass). Because of this, active and passive elements such as transistors, diodes, and resistors configured on the upper part of the semiconductor chip 2 are connected to each other, for example, using aluminum (Al).
Wiring and the like will not be damaged by the pressure caused by the above-mentioned crimping.

Moreover, since the upper part of the above-mentioned PSG protective film, that is, the upper surface of the semiconductor chip, is further covered with the polyimide resin layer 9 as described above, not only the upper components of the semiconductor chip 2 are not damaged, but also the well-known Due to the radiation resistance of polyimide, this structure also makes the IC resistant to radiation.

Solder cladding is applied to the bottom of the concave part of the sealing cap, and at the same time, a layer of aluminum/copper (Al-Cu), for example, is applied to the top surface of the polyimide resin.
Or titanium, tungsten, nickel (Ti
-W--Ni) is deposited by vapor deposition and the sealing cap 4 is heated to a predetermined temperature, that is, the melting point of the solder, so that the vapor-deposited metal film on the top surface of the polyimide resin and the bottom surface of the recess of the sealing cap are heated. Since it is soldered, heat dissipation is even more effective. In this case, since the polyimide resin has a heat resistance of 450° C., it can sufficiently withstand the melting point of ordinary low-melting point solder, and the polyimide resin will not be thermally damaged by the above-mentioned soldering process.

Furthermore, instead of the above-mentioned polyimide resin, a so-called junction coating resin (hereinafter abbreviated as JCR) used in ordinary power transistors may be used, and the same effect can be expected. The sealing cap 4 is desirably made of a metal plate having high thermal conductivity and good solderability, and preferably has a thickness of, for example, 0.2 to 0.5 mm.

FIG. 3 shows the structure of a package as a modified embodiment of the present invention, in which a folding step as shown in FIG. 3 is provided at the end of the sealing cap 4 as shown in FIG. The width d shown is set to be approximately equal to the width of the upper surface of the upper members 1a and 1b of the insulating stem member 1. And upper members 1a, 1b
The upper surface of the sealing cap 4 is metallized, and the metallized portion and the bottom surface of the end of the sealing cap 4 are soldered with solder 11.

In this way, the above-mentioned folding step 10 becomes the stem member 1.
It fits between the two upper members 1a and 1b located at the left and right ends of. That is, in this case, since the upper members 1a and 1b play the role of positioning members for the sealing cap 4, the bottom surface 4b of the concave portion of the sealing cap 4 is correctly aligned with the polyimide resin layer 9 coated on the semiconductor chip 2. This makes it possible to prevent an accident in which the concave side surface 4a of the cap 4 comes into contact with the bonding wire 3.

Furthermore, in Figure 3 of the above cap, 4
If another heat dissipation stud is newly erected in the recessed space shown as C and a heat dissipation fin is attached, the heat dissipation effect will be further improved.

According to actual experimental results using the IC package according to the present invention described above, the thermal resistance of the IC is as low as approximately 10°/W even when the heat dissipation fins are not erected. It is clear that this will happen. To create an IC package with this shape, it is sufficient to simply make the almost central part of the sealing cap 4 concave, and it does not require any major changes in other manufacturing processes or mounting processes, so it is inexpensive and large. Since the results can be obtained, great practical effects can be expected.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of an IC package with a conventional structure.
FIG. 2 shows an IC as a first embodiment of the present invention.
FIG. 3 is a side sectional view of an IC package as a second embodiment of the present invention. 1: Insulating stem member, 1a, 1b: Upper member, 2: Semiconductor chip, 3: Bonding wire, 4: Sealing cap, 5: External lead-out terminal,
8: Concave portion of the sealing cap, 9: Polyimide resin, 10: Folding step of the sealing cap.

Claims (1)

[Claims] 1. An integrated circuit package comprising: 1. A semiconductor chip is placed on an insulating stem member with the side on which the integrated circuit is formed facing upward; and the upper part of the stem member is covered with a sealing cap. , the sealing cap is made of a heat conductive material,
Further, a concave portion is provided in the sealing cap directly above the semiconductor chip, and the stem is sealed in such a manner that the bottom surface of the concave portion is in contact with a portion of the top surface of the semiconductor chip other than the area to which the wire is connected. An integrated circuit package characterized by: