Intel 640 User Guide - Page 67

Heatsink Clip Load Metrology

R

Thermal/Mechanical Design Guide

67

Appendix B Heatsink Clip Load

Metrology

B.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 LGA775 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.

B.2

Test Preparation

B.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

B.2.2.

To install the load cells, machine a pocket in the heatsink base, as shown in Figure 24 and

Figure 25. 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 (Refer to Figure 25).

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 additional load by artificially raising the heatsink base. The measurement offset

depends on the whole assembly stiffness (i.e. motherboard, clip, fastener, etc.). For example, the

Intel RCBFH-3 Reference Heatsink Design clip and fasteners assembly has a stiffness of around

380 N/mm [2180 lb/in]. In that case, a protrusion of 0.038 mm [0.0015”] will create an extra load

of 15 N [3.3 lb]. Figure 26 shows an example using the Intel RCBFH-3 Reference Heatsink

designed for the Pentium 4 processor in the 775–land LGA package.

Section	Page
Contents	3
Figures	6
Tables	7
Revision History	8
1 Introduction	9
1.1 Document Goals and Scope	9
1.1.1 Importance of Thermal Management	9
1.1.2 Document Goals	9
1.1.3 Document Scope	10
1.2 References	11
1.3 Definition of Terms	12
2 Processor Thermal/Mechanical Information	15
2.1 Mechanical Requirements	15
2.1.1 Processor Package	15
2.1.2 Heatsink Attach	17
2.1.2.1 General Guidelines	17
2.1.2.2 Heatsink Clip Load Requirement	17
2.1.2.3 Additional Guidelines	18
2.2 Thermal Requirements	18
2.2.1 Processor Case Temperature	18
2.2.2 Thermal Profile	19
2.2.3 TCONTROL	20
2.3 Heatsink Design Considerations	21
2.3.1 Heatsink Size	22
2.3.2 Heatsink Mass	22
2.3.3 Package IHS Flatness	22
2.3.4 Thermal Interface Material	23
2.4 System Thermal Solution Considerations	23
2.4.1 Chassis Thermal Design Capabilities	23
2.4.2 Improving Chassis Thermal Performance	23
2.4.3 Summary	24
2.5 System Integration Considerations	24
3 Thermal Metrology	25
3.1 Characterizing Cooling Performance Requirements	25
3.1.1 Example	26
3.2 Processor Thermal Solution Performance Assessment	27
3.3 Local Ambient Temperature Measurement Guidelines	27
3.4 Processor Case Temperature Measurement Guidelines	30
4 Thermal Management Logic and Thermal Monitor Feature	31
4.1 Processor Power Dissipation	31
4.2 Thermal Monitor Implementation	31
4.2.1 PROCHOT# Signal	32
4.2.2 Thermal Control Circuit	32
4.2.3 Operation and Configuration	33
4.2.4 On-Demand Mode	34
4.2.5 System Considerations	34
4.2.6 Operating System and Application Software Considerations	35
4.2.7 On-Die Thermal Diode	35
4.2.7.1 Reading the On-Die Thermal Diode Interface	35
4.2.7.2 Correction Factors for the On-Die Thermal Diode	36
4.2.8 THERMTRIP# Signal	37
4.2.8.1 Cooling System Failure Warning	37
5 Intel® Thermal/Mechanical Reference Design Information	39
5.1 Intel Validation Criteria for the Reference Design	39
5.1.1 Heatsink Performance Target	39
5.1.2 Acoustics	40
5.1.3 Altitude	40
5.1.4 Reference Heatsink Thermal Validation	41
5.1.5 Fan Performance for Active Heatsink Thermal Solution	41
5.2 Environmental Reliability Testing	42
5.2.1 Structural Reliability Testing	42
5.2.1.1 Random Vibration Test Procedure	42
5.2.1.2 Shock Test Procedure	42
5.2.2 Power Cycling	44
5.2.3 Recommended BIOS/Processor/Memory Test Procedures	44
5.3 Material and Recycling Requirements	44
5.4 Safety Requirements	45
5.5 Geometric Envelope for ATX Intel® Reference Thermal Mechanical Design	45
5.6 ATX Reference Thermal Mechanical Solution for the Intel® Pentium® 4 Processor in the 775–Land LGA Package	46
5.7 Reference Attach Mechanism	48
5.7.1 Structural Design Strategy	48
5.7.2 Mechanical Interface to the Reference Attach Mechanism	49
6 Acoustic Fan Speed Control	53
6.1 Acoustic Fan Speed Control	53
6.2 Thermal Solution Design	53
6.2.1 Compliance to Thermal Profile	53
6.2.2 Determine Thermistor Set Points	53
6.2.3 Minimum Fan Speed Set Point	54
6.3 Board and System Implementation	55
6.3.1 Choosing Fan Speed Control Settings	55
6.3.1.1 Temperature to begin Fan Acceleration	56
6.3.1.2 Minimum PWM Duty Cycle	58
6.4 Combining Thermistor and Thermal Diode Control	59

Intel 640 User Guide - Page 67

Appendix B Heatsink Clip Load, Metrology

Page 67 highlights