Could you provide Thermal Resistance for VBK048(48-BGA)?
I can't find it out on the datasheet of 001-98286 Rev. *G.
The Theta Ja value is 39 °C/W, where as the Psi Jt value 5 °C/W.
We do not provide the Theta Jb and Theta Jc values for our devices.
You can also use this Application Note as a reference - http://www.cypress.com/file/210756/download
Thanks and Regards,