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

Intel

Pentium

4 Processor in the 478-Pin Package Thermal Design Guidelines

Design Guide 11

2 Thermal Mechanical Information

2.1 Mechanical Requirements

2.1.1 Processor Package

The Intel

Pentium

4 processor in the 478-pin package is packaged in a flip-chip pin grid array 2

(FC-PGA2) package technology. Please refer to the processor datasheet for detailed mechanical

specifications of the 478-pin package.

The package includes an integrated heat spreader (IHS). The IHS spreads the non-uniform heat

from the die to the top of the IHS, out of which the heat flux is more uniform and on a larger

surface area. This allows more efficient heat transfer out of the package to an attached cooling

device. The IHS is designed to be the interface for mounting a heatsink. Details can be found in

the processor datasheet.

The processor connects to the motherboard through a ZIF surface mount socket. A description of

the socket can be found in the Intel

Pentium

4 Processor, 478-Pin Socket (mPGA478B) Design

Guidelines.

The processor package has mechanical load limits that are specified in the datasheet. These load

limits should not be exceeded during heatsink installation, removal, mechanical stress testing, or

standard shipping conditions. For example, when a compressive static load is necessary to ensure

thermal performance of the thermal interface material between the heatsink base and the IHS, this

compressive static load should not exceed the compressive static load specification given in the

processor datasheet.

The heatsink mass can also add additional dynamic compressive load to the package during a

mechanical shock event. Amplification factors due to the impact force during shock have to be

taken into account in dynamic load calculations. The total combination of dynamic and static

compressive load should not then exceed the processor datasheet compressive dynamic load

specification during a vertical shock. For example, with a 1 lbm heatsink, an acceleration of 50 g

during a 11ms shock results approximately in a 100 lbf dynamic load on the processor package. If

a 100 lbf static load is also applied on the heatsink for thermal performance of the thermal

interface material and/or for mechanical reasons, the processor package sees 200 lbf. The

calculation for the thermal solution of interest should be compared to the processor datasheet

specification.

It is not recommended to use any portion of the substrate as a mechanical reference or load-

bearing surface in either static or dynamic compressive load conditions.