1. Field of the Invention
The present invention relates to the field of semiconductor packaging.
2. Related Art
During a typical transfer molding process for making plastic semiconductor packages, multiple substrate panels are placed in a mold tool. The mold tool includes opposing platens and open cavities. Each substrate panel includes multiple substrates having electrically conductive paths, such as metal traces and vias, formed thereon. A semiconductor chip, and possibly other electrical components, is disposed on each of the substrates of the substrate panel. When the mold tool is closed, the opposing platens clamp down onto the substrate panels. A plastic mold compound, such as epoxy, is then injected into the open cavities, so as to encapsulate the semiconductor chip and the surrounding substrate surface. After the mold compound has cured, the substrate panels are removed from the mold tool, whereupon the mold compound may be further cured. Finally, the encapsulated substrate panels are cut, such as by sawing or punching, so as to singulate individual packages each including an encapsulated substrate with a semiconductor chip thereon.
Such conventional molding techniques are used to make packages having a metal leadframe substrate or a printed circuit board substrate. However, such molding techniques are not used to make packages having ceramic substrates. This is because conventional molding techniques damage the ceramic substrate panels that include the ceramic substrates. Ceramic substrate panels are brittle and are slightly warped due to the firing process used to make them. If ceramic substrate panels were placed in a mold tool and the opposing platens of the mold tool were to clamp down on the ceramic substrate panels, the clamping pressures would cause the brittle and slightly warped ceramic substrate panels to fracture or crack. On the other hand, laminate or leadframe substrate panels are flexible, and therefore are capable of withstanding the clamping pressures of the mold tool.
Since ceramic substrate panels cannot be molded, other techniques have been used to encapsulate semiconductor devices mounted on ceramic substrates. For example, metal or ceramic covers can be mounted on the ceramic substrate over the semiconductor device, or liquid encapsulation techniques may be used. These techniques are slower and more costly than molding techniques.
Accordingly, what is needed is a method for molding semiconductor packages that include a ceramic substrate.
Embodiments of the present invention include methods for making a package for a semiconductor chip or other electronic device, where the package includes a body of a molded encapsulant formed over the chip and a ceramic substrate. Accordingly, it is now possible to achieve the economic advantages of using a molding step to encapsulate the semiconductor chip, while at the same time using a ceramic substrate in the package.
In one embodiment, plural ceramic substrate panels each having a matrix of semiconductor chips thereon are precisely located on and attached to a temporary support member using an alignment tool. The member and the attached ceramic substrate panels are then placed in a mold tool. When the mold tool is closed, it clamps down on the member around the ceramic substrate panel, and not on the ceramic substrate panel itself. A mold compound is then injected into the mold tool to encapsulate the chips and ceramic substrate panels. Subsequently, packages each containing a chip are singulated from the encapsulated ceramic substrate panels.
Other aspects of the present invention will become apparent from the following description of the exemplary embodiments and from the accompanying drawings thereof.