Preliminary
PowerPC 750FL RISC Microprocessor
5.8.4 Heat Sink Mounting
Figure 5-10. Exploded Cross-Sectional View of Package 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
50 g
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 uncal-
ibrated accuracy. The relationship between the actual junction temperature and the temperature indicated 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 microprocessor, the calibration methods discussed in this document also
apply to the 750FL microprocessor.
In rare cases, the basic error of the TAU can be so large that a useful calibration cannot be achieved.
750flds60.fm.6.0
April 27, 2007
System Design Information
Page 61 of 65
IBM [ IBM ]
