DD 2.X
PowerPC 750FX RISC Microprocessor
Preliminary
5.8.4 Heat Sink Mounting
Figure 5-10. Package Exploded Cross-Sectional View with Several Heat Sink Options
Heat Sink
CBGA Package
Heat Sink clip
Adhesive
or
Thermal
Interface
Material
Printed
Circuit
Board
Option
Table 5-8. Maximum Heatsink Weight Limit for the CBGA
Force
Maximum
42.9 N
9.05 N
14.8 N
50g
Maximum dynamic compressive force allowed on the BGA balls
Maximum dynamic tensile force allowed on the BGA balls
Maximum dynamic compressive force allowed on the chip
Maximum mass of module + heatsink when heatsink is not bolted to card
5.8.5 Thermal Assist Unit
The thermal sensor in the Thermal Assist Unit (TAU) has not been characterized to determine the basic
uncalibrated accuracy. The relationship between the actual junction temperature and the temperature indi-
cated by THRM1 and THRM2 is not well known.
IBM recommends that the TAU in these devices be calibrated before use. Calibration methods are discussed
in the IBM Application Note Calibrating the Thermal Assist Unit in the IBM25PPC750L Processors.
Although this note was written for the 750L, the calibration methods discussed in this document also apply to
the 750FX.
In rare cases, the basic error of the TAU may be so large that a useful calibration cannot be achieved.
5. System Design Information
Page 54 of 63
Body_750FX_DS_DD2.X.fm.2.0
June 9, 2003
IBM [ IBM ]
