Intel 640 User Guide - Page 23

Processor Thermal/Mechanical Information

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Thermal/Mechanical Design Guide

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2.3.4

Thermal Interface Material

Thermal interface material application between the processor IHS and the heatsink base is

generally required to improve thermal conduction from the IHS to the heatsink. Many thermal

interface materials can be pre-applied to the heatsink base prior to shipment from the heatsink

supplier and allow direct heatsink attach, without the need for a separate thermal interface

material dispense or attach process in the final assembly factory.

All thermal interface materials should be sized and positioned on the heatsink base in a way that

ensures the entire processor IHS area is covered. It is important to compensate for heatsink-to-

processor attach positional alignment when selecting the proper thermal interface material size.

When pre-applied material is used, it is recommended to have a protective application tape over

it. This tape must be removed prior to heatsink installation.

2.4

System Thermal Solution Considerations

2.4.1

Chassis Thermal Design Capabilities

The ATX Intel reference thermal solution assumes that the chassis delivers a maximum T

A

of

38 °C at the inlet of the processor fan heatsink (refer to Section 5.1.1).

2.4.2

Improving Chassis Thermal Performance

The heat generated by components within the chassis must be removed to provide an adequate

operating environment for both the processor and other system components. Moving air through

the chassis brings in air from the external ambient environment and transports the heat generated

by the processor and other system components out of the system. The number, size, and relative

position of fans and vents determine the chassis thermal performance, and the resulting ambient

temperature around the processor. The size and type (passive or active) of the thermal solution

and the amount of system airflow can be traded off against each other to meet specific system

design constraints. Additional constraints are board layout, spacing, component placement,

acoustic requirements and structural considerations that limit the thermal solution size. For more

information, refer to the

Performance ATX Desktop System Thermal Design Suggestions

or

Performance microATX Desktop System Thermal Design Suggestions

documents available on the

http://www.formfactors.org/

web site.

In addition to passive heatsinks, fan heatsinks and system fans are other solutions that exist for

cooling integrated circuit devices. For example, ducted blowers, heat pipes and liquid cooling are

all capable of dissipating additional heat. Due to their varying attributes, each of these solutions

may be appropriate for a particular system implementation.

To develop a reliable, cost-effective thermal solution, thermal characterization and simulation

should be carried out at the entire system level, accounting for the thermal requirements of each

component. In addition, acoustic noise constraints may limit the size, number, placement, and

types of fans that can be used in a particular design.

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 23

System Thermal Solution Considerations

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