JPH0333074Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a semiconductor package with a heat sink that mounts a chip such as an IC or LSI.

[Conventional technology]

In recent years, the amount of heat generated and the heat density of ICs mounted in various electronic devices such as computer equipment have increased significantly due to higher integration and faster operation of the elements. By the way, heat is generally not desirable for ICs, and in order to realize highly reliable devices, it is necessary to keep the internal temperature of the IC below a specified temperature. For this reason, means and structures to suppress the temperature of ICs are extremely important, and measures such as supplying high wind speeds and cold air into the equipment, and improving the heat dissipation characteristics of the package structure itself that mounts the IC chips, are extremely important. Various efforts have also been made.
For example, conventional efforts have been made to improve heat dissipation characteristics by changing the material of the package from resin to ceramic materials such as alumina or beryllia, which have high thermal conductivity, or by making the package thinner and shortening the heat flow path. It's here. If the heat dissipation characteristics are still insufficient even after the above-mentioned improvements, the performance can be improved by bonding a comb-like heat sink to the package body using adhesive or brazing material, as shown in Figure 4. Ta.

FIG. 4 is a partially cutaway perspective view showing an example of a conventional semiconductor package with a heat sink.

In the figure, an IC chip 9 is mounted on one surface of a substrate 1, and a plurality of input/output terminals 5 are provided upright. A comb-shaped heat sink 2 a is bonded to the other surface of the substrate 1 with a heat sink adhesive 8 . On the chip mounting surface of board 1,
Further, wires 11 for connecting the IC chip 9 and the connection pads 6 formed on the substrate 1, and patterns 7 for connecting the connection pads 6 and the input/output terminals 5 are provided for electrical connection. Further, a cap 12 fixed to the substrate 1 so as to cover the IC chip 9 protects the IC chip 9 from external mechanical forces and isolates it from the outside air. Here, an alumina plate is generally used for the substrate 1, and a material having the same coefficient of linear expansion as the substrate 1 is selected for the heat sink 2a. For example, using a composition of copper and tungsten or a composition of copper and molybdenum
91742), this is to prevent thermal stress from occurring even when the bonding layer is bonded and integrated with the substrate 1, and cracks and peeling of the bonding layer do not occur.

[Problem that the invention attempts to solve]

However, the conventionally used copper-tungsten and copper-molybdenum compositions mentioned above have a specific gravity of 16 and 9, respectively, and are very heavy and difficult to handle, and the main components, tungsten and molybdenum, are expensive. This was a factor in raising the price of package. In addition, as ICs become more highly integrated, the number of pins and chip sizes increase, which tends to increase the size of the package. Air bubbles were a factor that hindered heat conduction.

[Means for solving problems]

The semiconductor package with a heat sink of the present invention is a ceramic package with a chip mounting part, a plurality of input/output terminals, and connection pads for connecting the input/output terminals and the chip on one side, and a heat sink bonded on the other side. The heat sink is made of an aluminum material and has a plurality of grooves on its joint surface with the ceramic plate.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing an embodiment of a semiconductor package with a heat sink of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a three-sided view of the heat sink in FIG. 1. A, b, and c are a front view, a bottom view, and a side view, respectively.

In FIGS. 1 and 2, the same components as in the conventional example are given the same reference numerals as in FIG. 4. In the figure, the present embodiment is constructed by bonding a heat sink 2 to a flat alumina substrate 1 on which a plurality of input/output terminals 5 are arranged upright. A mounting portion 4 formed on a smooth surface is provided approximately at the center of the lower surface of the substrate 1, and an IC chip 9 is attached to the mounting portion 4 using a chip fixing agent 10 such as a resin adhesive. is fixed. The electrical connection structure of the IC chip 9 and the mounting structure of the cap 12 are the same as those of the conventional example.

Here, the heat sink 2 is made of aluminum and has a bottom surface that is approximately the same in shape as the substrate 1.
A radiation fin is formed in a comb-tooth shape projecting upward on the surface other than the surface to which it is fixed. The heat sink 2 of this embodiment is provided with grooves 3 on its bottom surface, which is joined to the substrate 1, in order to isolate thermal stress caused by the difference in coefficient of linear expansion and to absorb overall elongation. As shown in FIG. 3, a plurality of grooves 3 are provided in a lattice pattern in the vertical and horizontal directions on the bottom surface, and the substrate 1 and the heat sink 2 are not joined to each other on the entire surface. This heat sink 2 is bonded and integrated to the surface of the board 1 opposite to the surface on which the mounting portion 4 is located by a heat sink fixing material 8 such as an epoxy resin adhesive mixed with powder of a high thermal conductivity material. . Since air bubbles remaining in the bonding layer during the fixing work can easily escape through the grooves 3, the degree of air bubble remaining is significantly smaller than in the case of a conventional heat sink without grooves. Bubbles in the fixed layer obstruct heat conduction, and therefore, in this embodiment, compared to the conventional example, heat conduction is not hindered by the bonding layer.

In the semiconductor package of this example,
The heat generated in the IC chip 9 is conducted from the chip adhesive 10 to the heat sink 2 via the substrate 1 and the heat sink adhesive 8, and is dissipated from the heat sink 2 into the surrounding air to suppress the temperature rise of the IC chip 9. At this time, the temperature of the substrate 1 and the heat sink 2 also increases, and they expand according to their respective coefficients of linear expansion. The linear expansion coefficient of alumina, which is the material of the substrate 1, is approximately 7×10 ^-6 /℃, while the heat sink 2
Aluminum, which is the material of the material, has a temperature of about 24×10 ^-6 /°C, so the elongation is about 3.4 times different, but since the elongation of the aluminum is absorbed by the grooves 3, the overall thermal stress is alleviated. Therefore, the reliability of the semiconductor package can be improved without peeling of the bonding layer or cracking of the substrate 1.
Moreover, the specific gravity of aluminum, the heat sink material, is 2.7, which is 1/6 or 1/3 lighter than the conventionally used copper-tungsten or copper-molybdenum, making it possible to reduce the weight of semiconductor packages. Furthermore, aluminum is inexpensive and has a low specific gravity, which reduces the weight used, and together with this, a low-cost package can be provided.

In the above embodiment, the heat sink 2 is bonded to the substrate 1 using a resin adhesive, but the present invention is not limited thereto. You can. In this case, a compatible material that enables brazing may be provided in advance on the mounting surface of the heat sink 2, and this can be realized using a known metallization technique.

[Effects of the invention] As explained above, the present invention suppresses thermal stress to a small level by bonding the surface of a heat sink made of aluminum with multiple grooves to a ceramic plate, thereby preventing cracks in the ceramic plate and bonding. This has the effect of preventing layer peeling and reducing the number of bubbles generated in the bonding layer, improving reliability of heat conduction and providing a lightweight and inexpensive semiconductor package with a heat sink.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a semiconductor package with a heat sink according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a three-sided view of the heat sink in FIG. 1. Reference symbols a, b, and c are a front view, a bottom view, and a side view, respectively, and FIG. 4 is a partially cutaway perspective view showing an example of a conventional semiconductor package with a heat sink. 1... Board, 2, 2a... Heat sink, 3...
...Groove, 4...Mounting section, 5...Input/output terminal, 6...
Connection pad, 7... pattern, 8... heat sink adhesive, 9... IC chip, 10... chip adhesive, 11... wire, 12... cap.

Claims (1)

[Scope of utility model registration request] A semiconductor package with a heat sink, which is provided with a chip mounting part, a plurality of input/output terminals, and a connection pad for connecting the input/output terminals and the chip on one surface, and a ceramic plate with a heat sink bonded on the other surface, 1. A semiconductor package with a heat sink, wherein the heat sink is made of an aluminum material and has a plurality of grooves on its joint surface with the ceramic plate.