Mounting RF Power transistor on to microstrip board

[rd_dinesh]

I designed a mask for rf power amplifier, the microstrip substrate(RT6006 0.8mm thickness) was etched, now I want to mount my transistor on to it. What are the techniques I can use to mount my CGH40010F power transistor(whose gate and drain are 1.7 mm above ground)?

 

[BigBoss]

You have to use a heatsink under the PCB and you will bury the transistor in it.
Refer to manufacturer's mounting instructions.

 

[albbg]

CGH40010F is the flanged version, so simply create a rectangular hole on the PCB little bit wider than the flange, in order to have the bottom of the transistor directly in contact with the heatsink. The surface of the heatsink has to be worked in order to have gate and drain terminals at the same quote of the PCB surface when the transistor is in place. When the bottom of the transistor touches the heatsink also the terminals have to touch the PCB tracks and viceversa. At this point tighten the screws and solder the two terminals on the PCB.
Where the heatsink goes in contact with the transistor it's good practice to define some grade of mechanical finishing to remove the imperfection due to the milling process. In addition you can use a thermally conductive paste between the transistor and the heatsink