Package Thermal Resistance of CQFP 44, TQFP 44

[thevan48]

Hi everybody,
I have to compare the thermal capacity of these packages for my chip: CQFP 44, PLCC 44, QFN 44 and TQFP 44; however i couldn't find the thermal resitance of CQFP 44, TQFP 44 and QFN 44.
Any body can help me?
Thanks alot,

 

[marce]

A part number would be helpful.
IPC-7093 Design and Assembly Process for Bottom Termination Components is a good guide for QFN based packages.
The data sheet for the relevant part will have thermal resistance figures and probably layout notes on PCB design issues such as number of thermal vias required.
The QFN packages by design tend to be the most thermaly efficient packages, most (not all) have an exposed die attach pad on the bottom to provide a good thermal interface to the PCB.