Intel 632xESB Thermal Solution Requirements, Characterizing the Thermal Solution Requirement

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Thermal Solution Requirements—Intel®6321ESB ICH

5.0Thermal Solution Requirements

5.1Characterizing the Thermal Solution Requirement

The idea of a “thermal characterization parameter” Ψ (the Greek letter psi), is a convenient way to characterize the performance needed for the thermal solution and to compare thermal solutions in identical situations (i.e., heating source, local ambient conditions, etc.). The thermal characterization parameter is calculated using total package power, whereas actual thermal resistance, θ (theta), is calculated using actual power dissipated between two points. Measuring actual power dissipated into the heat sink is difficult, since some of the power is dissipated via heat transfer into the package and board.

The case-to-local ambient thermal characterization parameter (ΨCA) is used as a measure of the thermal performance of the overall thermal solution. It is defined by Equation 1 and measured in units of °C/W.

Equation 1. Case-to-Local Ambient Thermal Characterization Parameter (ΨCA)

ΨCA =

TCASE – TLA

----------TDP---------------

The case-to-local ambient thermal characterization parameter, ΨCA, is comprised of ΨCS, the thermal interface material (TIM) thermal characterization parameter, and of ΨSA, the sink-to-local ambient thermal characterization parameter:

Equation 2. Case-to-Local Ambient Thermal Characterization Parameter (ΨCA)

ΨCA = ΨCS + ΨSA

ΨCS is strongly dependent on the thermal conductivity and thickness of the TIM between the heat sink and device package.

ΨSA is a measure of the thermal characterization parameter from the bottom of the heat sink to the local ambient air. ΨSA is dependent on the heat sink material, thermal conductivity, and geometry. It is also strongly dependent on the air velocity through the fins of the heat sink. Figure 5 illustrates the combination of the different thermal characterization parameters.

Intel® 631xESB/632xESB I/O Controller Hub for Embedded Applications

February 2007TMDG 13

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Contents February Thermal and Mechanical Design GuidelinesPage Contents Tables Revision HistoryDate Revision Description 001 Initial public releaseDesign Flow IntroductionThermal Design Process Reference Documents Definition of TermsDefinition of Terms Term DefinitionTitle Location Referenced DocumentsPackaging Technology Intel 6321ESB I/O Controller Hub Package Dimensions Top ViewIntel 6321ESB ICH-Packaging Technology Thermal Design Power TDP Thermal SpecificationsDie Case Temperature Intel 6321ESB I/O Controller Hub Thermal SpecificationsThermal Simulation Characterizing the Thermal Solution Requirement Thermal Solution RequirementsExample 1. Calculating the Required Thermal Performance Processor Thermal Characterization Parameter RelationshipsDevice CA º C/W at T LA = 45º C CA º C/W at T LA = 65º C Required Heat Sink Thermal Performance ΨCAHub @ 12.4 W Thermal Metrology Die Case Temperature MeasurementsZero Degree Angle Attach Methodology Thermal Solution Decision Flowchart Thermocouple Wire Die Substrate Cement + Thermocouple Bead Operating Environment Reference Thermal SolutionHeatsink Performance Mechanical Design Envelope Board-Level Components Keepout Dimensions Torsional Clip Heatsink Thermal Solution Assembly Torsional Clip Heatsink Board Component Keepout Heatsink OrientationThermal Interface Material Mechanical Interface MaterialClip Retention Anchors Heatsink ClipThermal Resistance C × in 2/W Pressure on IHSpsi End of Line End of Life§ § Reliability GuidelinesReliability Guidelines Test Requirement Pass/Fail CriteriaTorsional Clip Heatsink Thermal Solution Appendix a Thermal Solution Component SuppliersMechanical Drawing List Appendix B Mechanical DrawingsDrawing Description Torsional Clip Heatsink Assembly Drawing Torsional Clip Heatsink Drawing Heat Sink Foam Gasket Drawing Torsional Clip Drawing
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