1. Field of the Invention
This invention generally relates to a multi-chip package, and more particularly to a multi-chip package housing at least two chips within one package.
2. Description of the Related Art
For instance, a package used in a small camera such as digital camera and used in a charge coupled device(CCD), is constructed as a module including an image sensing chip and other peripheral chips for driving the image sensing chip.
FIG. 1 is a cross-sectional view showing a conventional multi-chip package. As shown in the drawing, two semiconductor chips 2 are attached on a substrate 1. The respective bonding pads of the semiconductor chips 2 are electrically connected to the substrate 1 through metal wires 3. The entire upper portion of resultant is encapsulated with a molding compound 4. A plurality of solder balls 5 are mounted on a lower portion of the substrate 1.
In the meantime, the conventional multi-chip package incurs following problems.
First, the substrate must have large size size the respective semiconductor chips are disposed horizontally on the substrate in a line. Therefore, the size of the package is increased as the number of the semiconductor chips is increased.
There is also occurred a considerable amount of inductance component in a long metal wire since the substrate and the bonding pads of the semiconductor chips are connected by metal wires. As a result, the electric property is degraded due to the inductance component.
Furthermore, the structural reliability of the package is degraded since the molding compound and the substrate have different coefficients of thermal expansion. Also, the semiconductor chips are completely surrounded by the molding compound, therefore heat-dissipating function in the package is not utilized actively.