Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines

Intel

Pentium

4 Processor in the 478-Pin Package Thermal Design Guidelines

48 Design Guide

3.3.2 Heatsink Mechanical Design Guidelines

This section defines the mechanical requirements for the interface between a processor

heatsink /fan /shroud assembly and the reference mechanical components (retention mechanism

and clips). These requirements are intended to support interface control in the design of a custom

thermal solution.

Requirement 1: Heatsink /fan /shroud assembly must stay within the volumetric keep-in defined

Figure 20.

Guideline: Rectangular heatsink base dimensions and tolerances:

X-dimension = 2.70 ±0.010 inch

Y-dimension = 3.28 ±0.010 inch

Z-dimension: Inset in bottom surface of heatsink base in each of four corners

should hold a z-dimension of 0.073 ±0.010 inch.

These dimensions are recommended to limit heatsink movement (rocking and

sliding) during lateral shock (x and y directions).

Requirement 2: The clip-bearing surface must meet the following specifications to ensure

adequate interface with the clip lever through its entire range of motion.

X and Y-dimensions: see Figure 21

Z-dimension: height of bearing surface above bottom surface of heatsink base

must be 1.817 ±0.007 inch

Clip bearing surface roughness must be as defined by SPI B-1 finish or better.

Requirement 3: Heatsink /shroud structural characteristics

Vertical load carrying capability: Each of the two clip bearing surfaces must be

capable of carrying 70 lb of load oriented in the z-direction. The sub-structure

(typically the heatsink) must be capable of receiving this load and transferring it

to the heatsink /package interface.

Lateral load carrying capability: The heatsink must be capable of carrying

100 lbs of load in both x and y-directions at the points of contact between the

heatsink base and RM.

Stiffness: The structure of the heatsink assembly must have a stiffness

equal to or greater than 30,000 lb/in along the z-axis to ensure

proper preload induced by the clips.

Requirement 4: Max mass and Center of Gravity (CG)

The combined mass of the reference heatsink/fan/shroud assembly is 370 g. The

mechanical reference components (retention mechanism and clip) have been

validated in mechanical shock and vibration according to the Intel validation

criteria defined section 3.1.3 with the reference heatsink. If a cooling solution