The present invention relates to a power transistor module for radio frequency applications, particularly for use in an amplifier stage in a radio base station or in a ground transmitter for TV or radio, wherein said power transistor module comprises a support plate, a power transistor chip arranged thereon, outer electrical connections projecting from the module for external connection and inner electrical connections connected between said transistor chip and said outer connections, at least one of said inner electrical connections comprising a first conductor pattern arranged on a flexible foil. The invention further comprises a power amplifier comprising said module, a method in the fabrication of said module, a method in the fabrication of a power amplifier, where said module is electrically connected to a circuit board mounted at a heat sink and to be mounted at said heat sink, and finally to a power amplifier manufactured according to the method.