Intel 5400 Series manual Overview, Test Preparation, Heatsink Preparation

Heatsink Clip Load Methodology

CHeatsink Clip Load Methodology

C.1 Overview

This section describes a procedure for measuring the load applied by the heatsink/clip/ fastener assembly on a processor package.

This procedure is recommended to verify the preload is within the design target range for a design, and in different situations. For example:

•Heatsink preload for the LGA771 socket.

•Quantify preload degradation under bake conditions.

Note: This document reflects the current metrology used by Intel. Intel is continuously exploring new ways to improve metrology. Updates will be provided later as this document is revised as appropriate.

C.2 Test Preparation

C.2.1 Heatsink Preparation

Three load cells are assembled into the base of the heatsink under test, in the area interfacing with the processor Integrated Heat Spreader (IHS), using load cells equivalent to those listed in Section C.2.2.

To install the load cells, machine a pocket in the heatsink base, as shown in Figure C-1and Figure C-2. The load cells should be distributed evenly, as close as possible to the pocket walls. Apply wax around the circumference of each load cell and the surface of the pocket around each cell to maintain the load cells in place during the heatsink installation on the processor and motherboard.

The depth of the pocket depends on the height of the load cell used for the test. It is necessary that the load cells protrude out of the heatsink base. However, this protrusion should be kept minimal, as it will create an additional load offset since the heatsink base is artificially raised. The measurement load offset depends on the whole assembly stiffness (i.e. motherboard, clip, fastener, etc.). For example, the Quad-Core Intel® Xeon® Processor 5400 Series CEK Reference Heatsink Design clip and fasteners assembly have a stiffness of around 160 N/mm [915 lb/in]. If the resulting protrusion is 0.038 mm [0.0015”], then a extra load of 6.08 N [1.37 lb] will be created, and will need to be subtracted from the measured load. Figure C-3shows an example using the Quad-Core Intel® Xeon® Processor 5400 Series CEK Reference Heatsink designed for the Quad-Core Intel® Xeon® Processor 5400 Series in the 771–land LGA package.

Note: When optimizing the heatsink pocket depth, the variation of the load cell height should also be taken into account to make sure that all load cells protrude equally from the heatsink base. It may be useful to screen the load cells prior to installation to minimize variation.

Quad-Core Intel® Xeon® Processor 5400 Series TMDG 83