Mechanical Enabling for the Intel Pentium 4 Processor in the 478-Pin Package

14
Design Effectiveness
Processor Package Pull-Out - 2
Required Preload is a Function of Clip and Board Stiffness
Heatsink inertial load
F
HS
= (Heatsink Mass)*(Acceleration
input)*(dynamic amplification)
Required preload
P
req
= F
HS
 How much preload is required?
 Linear spring-mass model used for 1
st
order assessment
 Assume zero socket retention force
k
MB
k
clip
+ k
MB
M
heatsink
M
heatsink
k
MB
k
clip
Acceleration
under shock
Local MB
stiffness
Clip
stiffness