An experimental thermal characterization of a 272 PBGA within an automotive engine controller module

Results are presented for the thermal characterization of a simulated automotive engine control module in both natural and forced convection environments. The module consists of a 4-layer printed circuit board mounted inside a cast aluminum box that has similar dimensions to an actual engine controller. A 272-lead plastic ball grid array (PBGA) package containing a thermal test die is mounted on the circuit board. The board also has auxiliary patch heaters attached to its surface which simulate the additional components in an engine controller. The aluminum box has cartridge heaters mounted on the outside of the box that simulate power dissipation from the power drivers. Results show that junction temperature rise above ambient is strongly dependent on die input power and the total power dissipation on the board. Junction temperature rise is more weakly dependent on cartridge heater input power, box orientation, and die size. Junction temperature rise above ambient divided by package power is a linear function of board temperature rise above ambient divided by package power