MPC8540CPX667JC datasheet(81/104 Pages) FREESCALE

81 / 104 page

MPC8540 Integrated Processor Hardware Specifications, Rev. 4

Freescale Semiconductor

Thermal

Ultimately, the final selection of an appropriate heat sink depends on many factors, such as thermal

performance at a given air velocity, spatial volume, mass, attachment method, assembly, and cost. Several

heat sinks offered by Aavid Thermalloy, Alpha Novatech, IERC, Chip Coolers, Millennium Electronics,

and Wakefield Engineering offer different heat sink-to-ambient thermal resistances, that will allow the

MPC8540 to function in various environments.

16.2.1 Recommended Thermal Model

For system thermal modeling, the MPC8540 thermal model is shown in Figure 45. Five cuboids are used

to represent this device. To simplify the model, the solder balls and substrate are modeled as a single block

29x29x1.47 mm with the conductivity adjusted accordingly. For modeling, the planar dimensions of the

die are rounded to the nearest mm, so the die is modeled as 10x12 mm at a thickness of 0.76 mm. The

bump/underfill layer is modeled as a collapsed resistance between the die and substrate assuming a

conductivity of 0.6 in-plane and 1.9 W/m•K in the thickness dimension of 0.76 mm. The lid attach

adhesive is also modeled as a collapsed resistance with dimensions of 10x12x0.050 mm and the

conductivity of 1 W/m•K. The nickel plated copper lid is modeled as 12x14x1 mm. Note that the die and

lid are not centered on the substrate; there is a 1.5 mm offset documented in the case outline drawing in

Figure 43.

MPC8540CPX667JC Datasheet(PDF) 81 Page - Freescale Semiconductor, Inc