FIELD OF TECHNOLOGY

The present application relates to a package that includes a leadframe that is at least partially encapsulated by a mold compound. More specifically, the present disclosure relates to a thermally conductive and electrically insulating isolation layer locked within a cavity of the mold compound.

BACKGROUND

Conventional external isolation layers for molded packages can have adhesion problems if leadframe die pads at a surface of the package mold compound need to be isolated using a single isolation layer. This occurs because it can be difficult to adhere the isolation layer to surfaces of the mold compound that are between or around the exposed die pads. The adhesion problem arises because the isolation layer and the mold compound have different material properties.

For these and other reasons, there is a need for the present invention.

SUMMARY

According to an embodiment of an integrated circuit package, the package includes a leadframe and a mold compound encapsulating at least a portion of the leadframe. The mold compound includes a cavity open at a bottom surface of the mold compound that exposes a bottom surface of the leadframe. A thermally conductive and electrically insulating isolation layer is locked within the bottom cavity of the mold compound and contacts the bottom surface of the leadframe.

According to an embodiment of a leadframe module, the leadframe module includes a leadframe with a first die pad and a second die pad. A first power semiconductor die is attached to a top surface of the first die pad and a second power semiconductor die is attached to a top surface of the second die pad. A mold compound encapsulates the first power semiconductor die, the second power semiconductor die, and at least a portion of the leadframe. The mold compound includes a first cavity open at a bottom surface of the mold compound that exposes a bottom surface of the first die pad, where the first cavity includes an etched first undercut spaced at a first distance above the bottom surface of the mold compound. A thermally conductive and electrically insulating first isolation layer fills the first cavity and the first undercut. Filling the first undercut of the first cavity locks the first isolation layer within the first cavity. The mold compound includes a second cavity open at the bottom surface of the mold compound that exposes a bottom surface of the second die pad, where the second cavity includes an etched second undercut spaced at a second distance above the bottom surface of the mold compound. A thermally conductive and electrically insulating second isolation layer fills the second cavity and the second undercut. Filling the second undercut of the second cavity locks the second isolation layer within the second cavity.

According to an embodiment of a method of forming an integrated circuit package, the method includes providing a leadframe that includes a die pad, a semiconductor die attached to a top surface of the die pad and a mold compound encapsulates the semiconductor die and the die pad. The die pad includes a bottom surface exposed at a bottom surface of the mold compound, where at least one side surface of the die pad includes a protruding part that extends in a transverse direction away from the at least one side surface. The protruding part is below the top surface of the die pad and above the bottom surface of the mold compound. The method includes forming a cavity within the bottom surface of the mold compound by etching the bottom surface of the die pad to a distance above the bottom surface of the mold compound that includes etching at least a portion of the protruding part. The method includes filling the cavity with a thermally conductive and electrically insulating isolation layer.

According to an embodiment of a method of forming an integrated circuit package, the method includes providing a leadframe that includes a die pad, a semiconductor die attached to a top surface of the die pad and a sacrificial layer abutting a bottom surface of the die pad. A mold compound encapsulates the semiconductor die, the die pad and the sacrificial layer, and a bottom surface of the sacrificial layer is exposed at a bottom surface of the mold compound. At least one side surface of the sacrificial layer includes a protruding part spaced above a bottom surface of the mold compound. The protruding part extend ends in a transverse direction away from the at least one side surface. The method includes removing the sacrificial layer including the protruding part to form a cavity that is open at the bottom surface of the mold compound and that exposes a bottom surface of the die pad. Removal of the protruding part of the sacrificial layer forms an undercut within the cavity. The method includes filling the cavity with a thermally conductive and electrically insulating isolation layer.

Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

