greater th an th e th erm al grease join t.
Heat sin ks are attach ed to th e package by m ean s of a sprin g clip to h oles in th e
prin ted-circu it board (see Figu re 19 ). Th is sprin g force sh ou ld n ot exceed 5.5 pou n ds.
Th erefore th e syn th etic grease offers th e best th erm al perform an ce, con siderin g th e low
in terface pressu re. Of cou rse, th e selection of an y th erm al in terface m aterial depen ds
on m an y factors -- th erm al perform an ce requ irem en ts, m an u factu rability, service tem -
peratu re, dielectric properties, cost, etc.
Silicone Sheet (0.006 inch)
Bare Joint
+
Floroether Oil Sheet (0.007 inch)
Graphite/Oil Sheet (0.005 inch)
Synthetic Grease
2
+
+
1.5
+
1
0.5
0
20
30
40
50
60
70
80
0
10
Contact Pressure (PSI)
Figure 21. Thermal Performance of Select Thermal Interface Material
PPC740 and PPC750 Hardware Specifications
38 of 43
Preliminary and subject to change without notice
IBM [ IBM ]
