Intel Pentium 4 Processor on 90 nm Process Thermal and Mechanical Design Guidelines

Mechanical Requirements

Intel

Pentium

4 on 90 nm Process Thermal Design Guide 13

2 Mechanical Requirements

2.1 Processor Package

The Pentium 4 processor on 90 nm process is packaged using Flip-Chip Micro Pin Grid Array 4

(FC-mPGA4) package technology. Refer to the Intel

Pentium

4 Processor on 90 nm Process

Datasheet for detailed mechanical specifications.

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

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

larger surface area (not the entire IHS 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 contacting a

heatsink. Details are in the Intel

Pentium

4 Processor on 90 nm Process Datasheet.

The processor connects to the motherboard through a 478-pin surface mount, zero insertion force

(ZIF) socket. A description of the socket can be found in the Intel

Pentium

4 Processor

478-Pin Socket (mPGA478) Design Guidelines.

The processor package has mechanical load limits that are specified in the processor 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, it should not exceed the corresponding 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 must 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 0.454 kg [1 lbm] heatsink, an

acceleration of 50 G during an 11 ms shock with an amplification factor of 2 results in

approximately a 445 N [100 lbf] dynamic load on the processor package. If a 445 N [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 890 N [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.