Abstract: A heatsink assembly and method of fabrication and use for high power RF LDMOS transistors such as those used in mobile telephone basestation pre-antenna amplifiers wherein die attachment to the heatsink flange occurs prior to leadframe/spacer-to-flange bonding. Various bonding methods are disclosed which do not compromise the die-to-flange attachment bond. A unique leadframe/spacer/flange heatsink package is also disclosed which automatically properly orients attachment of the leadframe/spacer to the flange, and provides for a thickened spacer. A unique leadframe having contact projections also avoids later wire bonding. A unique leadframe/spacer/lid combination is disclosed which allows in one step the bonding of the leadframe to the flange, electrically contacting the die, and encapsulation.

Abstract: A sealable hermetic microchip package includes a vent therein that permits gas to escape during the sealing operation, but then itself is sealed at the completion of the sealing operation to render the package hermetic. The venting of gas from the interior of the package avoids the buildup of internal pressure during the sealing operation that can introduce bubbles and other faults into the sealing material. The vent may be a channel in the sealing surface of the lid of the package that is initially open, and then fills with the seal material as it flows to effect the seal. The vent may also be a hole in the lid that is sealed by the flow of a bead of the seal material. An equivalent approach to venting provided that the lid be mounted on standoffs that flow during sealing to permit the lid to settle onto the base of the package.