Intel® Pentium® 4 Processor In the 423-pin Package Thermal Design Guidelines ORDER NUMBER: 249203-001 NOVEMBER, 2000
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines Information in this document is provided in connection with Intel products. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines CONTENTS 1 INTRODUCTION ------------------------------------------------------------------------------------------------------------------------------------------------- 6 1.1 Document Goals ----------------------------------------------------------------------------------------------------------------------------------------------- 6 1.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 8.4.1 Operating System & Application Software Considerations--------------------------------------------------------------------------------- 26 8.5 Legacy Thermal Management Capabilities----------------------------------------------------------------------------------------------------------- 26 8.5.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines FIGURES Figure 1. Pentium® 4 processor Package Outline........................................................................................................ 8 Figure 2. Example of Air Exchange through a PC Chassis........................................................................................ 10 Figure 3. Heat Sink Base Dimensions...................................................................................................
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 1 INTRODUCTION In a system environment, the processor's temperature is a function of both the system and component thermal characteristics. The system level thermal constraints consist of the local ambient temperature at the processor and the airflow over the processor as well as the physical constraints at and above the processor.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines • TAMBIENT-EXTERNAL - the measured ambient temperature at the OEM defined external system location. • TAMBIENT-MAX - the target worst-case local ambient temperature. This can be determined by placing the system in maximum external temperature conditions and measuring the ambient temperature locally surrounding the processor. Under these conditions, TLA = TAMBIENT-MAX.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 2 IMPORTANCE OF THERMAL MANAGEMENT The objective of thermal management is to ensure that the temperatures of all components in a system are maintained within functional limits. The functional temperature limit is the range within which the electrical circuits can be expected to meet their specified performance requirements.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 4 THERMAL SPECIFICATIONS Refer to the Pentium 4 processor in the 423-pin Package Datasheet, for the thermal specifications of the Pentium 4 processor. In order to ease the burden on chassis cooling solutions a new Thermal Monitor feature has been integrated into the silicon of the Pentium® 4 processor.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 5 DESIGNING FOR THERMAL PERFORMANCE In designing for thermal performance, the goal is to keep the processor within the operational thermal specifications. Failure to do so will shorten the life of the processor and potentially cause erratic system behavior. The thermal design is required to ensure these operational thermal specifications are maintained.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines sink poses to the air and the more likely the air will travel around the heat sink instead of through it unless the bypass is small. Air traveling around the heat sink, rather than through, will have little affect on cooling the processor. 5.3 Heat Sink Solutions One method of improving thermal performance is to increase the surface area of a device by attaching a metallic heat sink.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines TOP VIEW NOTES 4 ALL DISPLAYED DIMENSIONS ARE CRITICAL TO FUNCTION. 5 THE FIN STRUCTURE ASSEMBLED TO THE TOP SURFACE OF THE BASE MAY NOT INTRUDE ON ZONE A. 6 DATUM A IS DEFINED AS THE BOTTOM OF THE PART. 7 THIS THICKNESS MUST BE MAINTAINED BETWEEN ZONE A AND DATUM A . 8 FLATNESS ZONE B IS REQUIRED FOR PROCESSOR REFERENCING AND THERMAL INTERFACE APPLICATION.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines ( .200 2X ZONE A ) ( .200 13. THE COMPLETE WILLAMETTE THERMAL SOLUTION MUST FIT WITHIN THE VOLUMETRIC CONSTRAINTS DEFINED ON THIS SHEET. ) 14. UNLESS OTHERWISE SPECIFIED ALL NON REFERENCE DIMENSIONS ON THIS SHEET ARE MAXIMUMS. 7 15 MAXIMUM HEIGHT OF FAN. SMALLER GEOMETRIES SUCH AS SCREWS HEADS, CLIPS, OR ALIGNMENT FEATURES MAY EXTEND UP TO 2.370" MAX. (CTF: I) TOP 2.730 3.330 15 2.220 H 2X .745 MIN 2X 45.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 5.5 Thermal Interface Management To optimize the heat sink design for the Pentium® 4 processor, it is important to understand the impact of factors related to the interface between the processor and the heat sink. Specifically, the bond line thickness, interface material area and interface material thermal conductivity should be selected to realize the most effective thermal solution. 5.5.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines Intel has determined through mechanical characterization that the use of phase change thermal interface materials may lead to motherboard, processor, and /or surface mount component damage in mechanical shock or mechanical drop testing. Phase change thermal interface materials create a strong adhesive bond between the processor package and heat sink that can lead to large deflections and high stresses.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 5.6.2 Direction For passive cooling solutions, if the fan(s) is (are) not moving air through the heat sink, then little cooling can occur and the processor may operate above the specified temperature. Two possibilities exist for blowing air through the heat sink of a Pentium® 4 processor. Air can be blown horizontally, parallel to the baseboard, which blows the air through the length of the heat sink.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines 6 ALTERNATIVE COOLING SOLUTIONS In addition to passive heat sink, fan heat sinks and system fans, other solutions 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.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 7.1 Thermal Metrology for Pentium® 4 processors 7.1.1 Thermal Resistance The thermal resistance value from case-to-local ambient (ΘCA) is used as a measure of the cooling solution's thermal performance. Thermal resistance is measured in units of °C/W.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines 7.1.2 Thermal Solution Performance All processor thermal solutions attach to the processor at the IHS. The system thermal solution must adequately control the local ambient air around the processor (TLA). The lower the thermal resistance between the processor and the local ambient air, the more efficient the thermal solution.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines TLA 1.0” Air Flow 0.5 to 1.0” TLA Air Flow ~2” Heatsink with Fan Passive Heatsink 000912a Figure 7. Guideline Locations for Measuring Local Ambient Temperature 7.1.4 Measurements for Processor Thermal Specifications To appropriately determine the thermal properties of the system, measurements must be made. Guidelines have been established for proper techniques for measuring processor temperatures.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines • Route the thermocouple wires through the hole in the heat sink base and attach it to the processor IHS. The use of more viscous adhesives and minimizing the use of drying accelerators will prevent problems with the adhesive spreading. • A small fixture may be required to hold the thermocouple and apply a steady force during the curing process to ensure the thermocouple is making contact with the IHS.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines 7.2 Thermal Test Vehicle to Processor Thermal Performance Correction Factor Intel releases Thermal Test Vehicles (TTV) for use by system and heat sink solution thermal designers prior to processor availability. The Thermal Test Vehicles approximate the thermal behavior of the processor; however, there is typically a difference in power density and power uniformity.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines A new on-die thermal management feature on the Pentium® 4 processor called Thermal Monitor, resolves these issues so that thermocouples are no longer needed. By using a highly accurate on-die temperature sensing circuit and a fast acting temperature control circuit (~50ns) the processor can rapidly initiate thermal management control.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines PROCHOT# Normal clock Internal clock Duty cycle control Resultant internal clock Figure 11. Internal Clock Modulation 8.3 Operation and Configuration The Thermal Monitor Feature is always enabled. But, to maintain compatibility with previous generations of processors having no integrated thermal logic, the clock modulation portion of Thermal Monitor is disabled by default.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines 8.4 System Considerations The Thermal Monitor feature may be used in a variety of ways, depending upon the system design requirements and capabilities. Intel requires the thermal control circuit to be enabled for all Pentium® 4 processor systems. At a minimum, the thermal control circuit supplies an added level of safety against loss in processor availability due to an over temperature situation.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines No activation expected Application/benchmark maximum Processor Performance Max Thermal control circuit regularly active Sporadic activation NOT TO SCALE 70% EMTS Max Power Chassis Cooling Capacity Figure 13. Processor Performance versus System Cooling Capability 8.4.
Pentium® 4 Processor in the 423-pin Package Thermal Design Guidelines models of the thermal diode sensors are described in datasheets available from the thermal diode sensor manufacturers. Processor Temperature The processor thermal diode should not be relied upon to turn on fans, warn of processor cooling system failure or predict the onset of thermal control circuit. As mentioned earlier, the processor’s high thermal ramp rates make this unfeasible. An illustration of this is as follows.
Pentium® 4 processor in the 423-pin package Thermal Design Guidelines functioning or allow a graceful system shutdown. If no thermal management action is taken, the silicon temperature may exceed ~135°C causing THERMTRIP# to go active and shut down the processor. Regardless of the system design requirements or cooling solution ability, the Thermal Monitor feature must still be enabled to guarantee proper processor operation.
