THS4521: Thermal resistance from junction to bottom of case

Part Number:THS4521

Hi,

Please provide the thermal resistance from junction to bottom of case for the THS4521 (DGK) package. The datasheet lists a large Rjb value of 115.3 °C/W, and I would like to use under-fill to improve the thermal performance. I will need to know the resistance to the bottom of the case to support my analysis. 

Thank you,

HSG