R Intel® Pentium® 4 Processor in the 478-Pin Package Thermal Design Guidelines Design Guide May 2002 Document Number: 249889-003
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R ® 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.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Contents 1 Introduction ..........................................................................................................................7 1.1 1.2 2 Thermal Mechanical Information .......................................................................................11 2.1 2.2 2.3 2.4 3 Design Guide References...................................................................................................
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.1 3.2 3.3 4 Intel Validation Criteria for the Reference Design.................................................37 3.1.1 Heatsink Performance...........................................................................37 3.1.1.1 Reference Heatsink Performance Target ............................37 3.1.1.2 Altitude .................................................................................37 3.1.1.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figures Figure 1. Processor IHS Temperature Measurement Location.........................................13 Figure 2. Processor Thermal Resistance Relationships ...................................................16 Figure 3. Guideline Locations for Measuring Local Ambient Temperature (not to scale) .20 Figure 4. Desired Thermocouple Location ........................................................................22 Figure 5.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Revision History Rev. No. Description Date -001 Initial Release. August 2001 -002 • Update for the support of the Intel Pentium 4 processor with 512 KB L2 cache on .
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 1 Introduction In this document, when a reference is made to the processor and/or the Intel® Pentium® 4 processor in the 478-pin package, it is intended that this includes the Intel® Pentium® 4 processor in the 478-pin package and the Intel® Pentium® 4 processor with 512 KB L2 cache on .13 micron process, unless it is otherwise specified.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R The physical dimensions and thermal specifications of the processor that may be used in this document are for illustration only. Refer to the corresponding processor datasheet for the product dimensions, thermal power dissipation and maximum case temperature. In case of conflict, the data in the datasheet takes precedence over any data in this document.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 1.1 References Material and concepts available in the following documents may be beneficial when reading this document. Document ® ® ® ® ® ® ® ® ® ® Order Number Intel Pentium 4 Processor in the 478-pin Package Datasheet Intel Pentium 4 Processor with 512KB L2 Cache on.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Term 10 Description Thermal Monitor The Intel Pentium 4 processor in the 478-pin package implements thermal management features consisting of: an on-die thermal diode, reference current source, comparator, external bus signal, thermal control circuit and processor registers to assist with managing thermal control of the processor.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2 Thermal Mechanical Information 2.1 Mechanical Requirements 2.1.1 Processor Package The Intel® Pentium® 4 processor in the 478-pin package is packaged in a flip-chip pin grid array 2 (FC-PGA2) package technology. Please refer to the processor datasheet for detailed mechanical specifications of the 478-pin package. The package includes an integrated heat spreader (IHS).
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.1.2 Heatsink Attach There are no features on the mPGA478 socket to directly attach a heatsink: a mechanism must be designed to support the heatsink.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.2 Thermal Specifications 2.2.1 Processor Case Temperature and Power Dissipation Refer to the processor datasheet for processor thermal information. Thermal information for the processor is given in terms of maximum case temperature specification and thermal design power. These values may depend on the processor frequencies and also include manufacturing variations.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R extruded heatsink may not be sufficient to cool the entire range of thermal design power. It is expected that more advanced cooling techniques will be necessary. In designing a cooling solution, 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.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.2.2.1.2 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.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R ΘCA = (TC - TA) / PD (Equation 1) Where: ΘCA = Thermal resistance from case-to-local ambient (°C/W) TC = Processor case temperature (°C) TA = Local ambient temperature in chassis around processor (°C) PD = Processor power dissipation (W) (assume all power goes through the IHS) The thermal resistance of the processor case-to-local ambient, ΘCA, is comprised of ΘCS , the thermal interface material thermal resistanc
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.2.2.3 Example The cooling performance ΘCA is then defined using the notion of thermal resistance described above: • Define a target case temperature TC,F and corresponding thermal design power TDPF from thermal specifications at a target frequency given in the processor datasheet. • Define a target local ambient temperature around the processor, TA.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R In addition to passive heatsinks, fan heatsinks 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.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.3 Thermal Metrology for the Intel® Pentium® 4 Processor in the 478-Pin Package 2.3.1 Processor Cooling Solution Performance Assessment Section 2.3 discusses guidelines for testing thermal solutions, including measuring processor temperatures. In all cases, power dissipation and temperature measurements must be made to validate a cooling solution.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R can help evaluate the potential impact of the chassis. This barrier is typically clear Plexiglas*, extending at least 4 inches in all directions beyond the edge of the thermal solution. Typical distance from the motherboard to the barrier is 3 inches (76.2 mm) to 3.5 inches (88.9 mm). For even more realistic airflow, the motherboard should be populated with significant elements like memory cards, AGP card, chipset heatsink.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.3.3 Processor Case Temperature Measurement Guidelines To ensure functionality and reliability, the Intel Pentium 4 processor in the 478-pin package is specified for proper operation when TC is maintained at or below the value listed in the processor datasheet. The measurement location for TC is the geometric center of the IHS. Figure 1 shows the location for TC measurement.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 4. Desired Thermocouple Location 3. 4. 5. 6. After the marks are scribed, clean the desired thermocouple attach location with a mild solvent and a lint-free wipe or cloth. Alcohol or acetone should suffice. Cleanliness of the part is critical for a strong epoxy bond after curing.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R IHS. The entire bead should be submerged and it is best to have insulated wires protruding from the epoxy. (See following figure). Figure 6. Thermocouple Bead Covered with Epoxy 9. Add other tack-downs of epoxy along the length of wire to provide strain relief for the thermocouple wire. Remove any small epoxy dots or lines that have been accidentally added after the epoxy cures. 10.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.3.3.2 Heatsink Preparation – Rectangular (Cartesian) Geometry To measure the case temperature, a heatsink must be mounted on the processor to dissipate the heat to the environment. The heatsink base must be grooved to allow a thermocouple to be routed from the center of the heatsink without altering the IHS for heatsink attachment. The groove in the heatsink has two features. The first is a 0.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.3.3.3 Heatsink Preparation – Radial (Cylindrical) geometry For some heatsinks that have a radial geometry (see Figure 9), it may be necessary to locate the center of the heatsink using features in the fin pattern. For example, the 52-fin radial heatsink of the Intel reference design for the Intel® Pentium® 4 processor in the 478-pin package (refer to section 3.3 and Figure 19) requires the following procedure: 1.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 6. 7. Refer to section 2.3.2 to setup the thermocouples used for TA measurement, and connect them to a thermocouple meter. Depending on the overall experimental setup, the time needed to have stable thermal conditions may vary. TA and TC measurements are valid once constant (refer to section 2.3.4.3) for application to the thermal test vehicle).
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R The recommended DC-power supply rating is listed in Table 1. The power supply should be able to deliver more current if necessary to cover for die resistance variations. Table 1. Recommended DC Power Supply Ratings Target Die Power Level Power Supply Rating 20 W 40 V and 1 A 25 W 45 V and 1 A 30 W 45 V and 1 A 35 W 50 V and 1 A 40 W 55 V and 1 A 50 W 60 V and 1.5 A 60 W 65 V and 1.5 A 70 W 70 V and 1.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 8. Connect the heater resistor of TTV to a DC power supply. Connect current and voltage meters as shown in the following figure. Figure 10. Electrical Connection for Heater Voltage Meter + _ V Heater Resistor _ I + + DC Power Supply _ Current Meter 9. Refer to section 2.3.2 to setup the thermocouples used for TA measurement, and connect them to a thermocouple meter. 10.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Table 2. TTV Correction Factors Thermal Resistance Intel® Pentium® 4 Processor in the 478-Pin Package Intel® Pentium® 4 Processor with 512KB L2 Cache on .13 Micron Process ΘCS 0.948 1.151 ΘSA 0.999 1.014 ΘCA 0.985 1.053 ΘCA correction factors should be used for the reference thermal design described in Chapter 3, or when the ratio ΘCS/ΘSA is similar to this design (~ 0.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R added margin may be necessary to ensure the processor silicon does not exceed its maximum specification (i.e., clock modulation may have to be turned on when the case temperature is significantly below its maximum specification to ensure the processor does not overheat). This added margin might have a substantial, and unacceptable, impact on system performance.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 11. Thermal Sensor Circuit Temperature sensing diode Current comparator PROCHOT# Reference current source The PROCHOT# signal is available internally to the processor as well as externally. External indication of the processor temperature status is provided through the bus signal PROCHOT#. When the processor temperature reaches the trip point, PROCHOT# is asserted.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 12. Concept for Clocks under Thermal Monitor Control PROCHOT# Normal clock Internal clock Duty cycle control Resultant internal clock 2.4.3 Operation and Configuration To maintain compatibility with previous generations of processors, which have no integrated thermal logic, the thermal control circuit portion of Thermal Monitor is disabled by default.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R length of time that the clocks are disabled remains constant, and the time period that the clocks are enabled is adjusted to achieve the desired ratio. For example, if the clock disable period is 3 µs, and a duty cycle of ¼ (25%) is selected, the clock on time would be reduced to approximately 1 µs [on time (1 µs) ÷ total cycle time (3 + 1) µs = ¼ duty cycle]. Similarly, for a duty cycle of 7/8 (87.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 2.4.5 Operating System and Application Software Considerations The Thermal Monitor feature and its thermal control circuit work seamlessly with ACPI compliant operating systems. The Thermal Monitor feature is transparent to application software since the processor bus snooping, ACPI timer, and interrupts are active at all times.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Processor Temperature Figure 13. Thermal Diode Sensor Time Delay Temperature is averaged over 1/16th second Temperature is reported 1/16th second later Processor temperature ramp Time in 1/16th second intervals 2.4.6.2 THERMTRIP# In the event of a catastrophic cooling failure, the processor will automatically shut down when the silicon temperature has reached approximately ~135 °C.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R This page is intentionally left blank.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3 Critical to Function Dimensions of Intel Reference Cooling Solution 3.1 Intel Validation Criteria for the Reference Design 3.1.1 Heatsink Performance 3.1.1.1 Reference Heatsink Performance Target The Intel reference heatsink is identical for the Intel® Pentium® 4 processor in the 478-pin package and the Intel® Pentium® 4 processor with 512KB L2 cache on .13 micron process.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.1.1.3 Reference Heatsink Thermal Validation The Intel reference heatsink is validated within specific boundary conditions based on the methodology described section 2.3, and using a thermal test vehicle (refer to section 2.3.4). Testing is done on bench top test boards at ambient lab temperature.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.1.3 Structural Reliability of Thermal Solution Assembly Structural reliability tests consist of unpackaged, board-level vibration and shock tests of a given thermal solution in assembled state. The thermal solution should be capable of sustaining thermal performance after these tests are conducted; however, the conditions of the tests outlined here may differ from your own system requirements. 3.1.3.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.1.3.3 Shock Test Procedure Recommended performance requirement for a motherboard: • Quantity: 3 drops for + and - directions in each of 3 perpendicular axes (i.e., total 18 drops). • Profile: 50 G trapezoidal waveform, 11 ms duration, 170 in./sec minimum velocity change. • Setup: Mount sample board on test fixture. Figure 15.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.1.3.5 Recommended BIOS/CPU/Memory Test Procedures This test is to ensure proper operation of the product before and after environmental stresses, with the thermal mechanical enabling components assembled. The test shall be conducted on a fully operational motherboard that has not been exposed to any battery of tests prior to the test being considered.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.1.5 Safety Requirements Heatsink and attachment assemblies shall be consistent with the manufacture of units that meet the safety standards: • UL Recognition-approved for flammability at the system level. All mechanical and thermal enabling components must be a minimum UL94V-2 approved. • CSA Certification. All mechanical and thermal enabling components must have CSA certification.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.2 Enabling Component Mechanical Envelope Figure 16, Figure 17, and Figure 18 show the overall keep-out and keep-in dimensions for the reference thermal/mechanical enabling design. Figure 16 and Figure 17 show the motherboard keep-outs and height restrictions under the enabling component region. Figure 18 shows the overall volumetric keep-in for the enabling component assembly.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 16.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 17.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 18. Volumetric Keep-in for Enabling Components NOTES: 1. Length in mm (inches) 2.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Reference Solution for the Intel® Pentium® 4 Processor in the 478-Pin Package 3.3 Note: The thermal mechanical reference design for the Intel® Pentium® 4 in the 478-pin package has been validated according to the Intel validation criteria given in Section 3.1, and using all the reference components as described in this document along with the reference thermal mechanical enabling components for the chipset.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.3.2 Heatsink Mechanical Design Guidelines This section defines the mechanical requirements for the interface between a processor heatsink /fan /shroud assembly and the reference mechanical components (retention mechanism and clips). These requirements are intended to support interface control in the design of a custom thermal solution.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R based the reference mechanical components uses a heatsink heavier than 370 g, the whole platform should be validated against the customer criteria. The combined center of gravity of the heatsink /fan /shroud assembly must be no greater than 1.0 inch [25.4 mm] above the top surface of the processor IHS. Figure 20. Heatsink, Fan, and Shroud Assembly Volumetric Keep-in NOTE: All dimensions in inches Figure 21.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 3.3.3 Reference Heatsink Attach Clip Information Guidelines for heatsink attach clip are given section 2.1.2. More specifically, the reference heatsink clip for the Intel® Pentium® 4 processor in the 478-pin package is latched to the retention tab features at each corner of the retention mechanism (see reference retention mechanism tab features and reference clip design details in Appendix B).
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R 4 Conclusion As the complexities of today’s microprocessors increase, the power dissipation requirements become more exacting. Care must be taken to ensure that the additional power is properly dissipated. Heat can be dissipated using passive heatsinks, fans and/or active cooling devices. Incorporating ducted airflow solutions into the system thermal design can yield additional margin.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R This page is intentionally left blank.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Appendix A: Thermal Interface Management To optimize the heatsink design for the Intel® Pentium® 4 processor in the 478-pin package, it is important to understand the impact of factors related to the interface between the processor and the heatsink base. Specifically, the bond line thickness, interface material area and interface material thermal conductivity should be managed to realize the most effective thermal solution.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R This page is intentionally left blank.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Appendix B: Mechanical Drawings Figure 22 through Figure 26 reference the mechanical enabling components for the Intel® Pentium® 4 processor in the 478-pin package. Note: Shock and vibration validation as well as thermal validation have been completed according to the validation criteria given section 3.1. However, Intel reserves the right to make changes and modifications to the design as necessary.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 22.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 23.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 24.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 25.
® ® Intel Pentium 4 Processor in the 478-Pin Package Thermal Design Guidelines R Figure 26.
