Intel Pentium 4 Guide

Intel®Pentium®4 Processor
in the 423-pin Package
Thermal-Mechanical Support
Design Guide
Version 1.0
Reorder Number 249348-001
January 2001

Intel® Pentium® 4 Processor in the 423-pin Package Thermal-Mechanical Support Design Guide
Version 1.0
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DISCLAIMERS
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Copyright ?2000 Intel Corporation. All rights reserved.
Version 1.0, December 2000
† Third-party brands and names are the property of their respective owners.
Revision History
Version Revision History Date
1.0 Initial release December 2000

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Contents
1. Overview...........................................................................................................................4
1.1 Related Documents ......................................................................................................4
2. Thermal-Mechanical Support Solution.....................................................................5
2.1 Motherboard Design .....................................................................................................7
2.2 Chassis Design ............................................................................................................8
2.3 Hardware.....................................................................................................................9
3. Conclusion.......................................................................................................................9
Figures
Figure 1. Direct Chassis-Attach Example......................................................................................5
Figure 2. ATX Motherboard Hole Locations for Direct Chassis-Attach ............................................7
Figure 3. ATX Chassis Mounting Holes for Pentium® 4 Processors ...............................................8
Tables
Table 1. Related Documents .......................................................................................................4
Table 2. Design Summary ...........................................................................................................6

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1. Overview
This design guide outlines a successful thermal-mechanical support solution for the Intel®
Pentium® 4 processor in the 423-pin package. The recommended solution is one proposed
method to support large-mass heatsinks during shipping and handling of the product. Board
and system designers should follow the recommendations in this design guide to allow
interchangeable ATX motherboards and chassis that support first-generation Pentium 4
processors. It is the responsibility of the supplier, OEM, and system integrator to test and
validate the final system solution.
1.1 Related Documents
Table 1. Related Documents
Document Location
ATX Specification, Version 2.03 http://www.teleport.com/~ffsupprt/

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2. Thermal-Mechanical Support Solution
Intel’s reference thermal-mechanical support solution for the Intel® Pentium® 4 processor
consists of:
?? Heatsink
?? Heatsink clips
?? Thermal interface material
?? Retention mechanism(s)
?? Chassis standoffs
Large-mass heatsinks on ATX form factor motherboards may cause excessive board
deflection during shipping and handling and may cause damage to board-level components.
Direct-attach of the retention mechanism to the chassis wall, as shown in Figure 1, is
recommended for all Intel® Pentium® 4 processor system solutions.
Figure 1. Direct Chassis-Attach Example
Retention Mechanism
(two-piece enabled-
solution shown as
example)

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Direct chassis-attach is one method that has been tested for managing large-mass heat sinks
during mechanical shock and vibration conditions. There may be some chassis,
motherboard, and heatsink combinations in which direct chassis-attach may not eliminate
the damage induced by large motherboard deflections. It is the responsibility of the
supplier, OEM, and system integrator to perform mechanical shock and vibration
validation on all shipped configurations.
Table 2summarizes the design impacts for the direct chassis-attach solution; the impacts
are detailed in the following sections.
Table 2. Design Summary
Component Design Solution
Motherboard Locate retention mechanism at recommended location
Chassis Add four (4) removable standoffs at recommended locations

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2.1 Motherboard Design
The retention mechanism should be located in relation to the ATX mounting holes as
shown in Figure 2to allow for direct attachment to the chassis. The two-piece enabled
retention mechanism cannot be pre-attached to the motherboard. Therefore, motherboards
intended for use by system integrators should supply two (2) retention mechanisms and two
(2) heatsink clips with each board. Intel boxed processors will not include these
components. ATX chassis will provide four (4) removable standoffs and four (4) screws
that will attach the retention mechanisms and motherboard to the chassis.
Figure 2. ATX Motherboard Hole Locations for Direct Chassis-Attach

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2.2 Chassis Design
The retention mechanism is attached to the chassis via four (4) standoffs, as shown in
Figure 3. These standoffs are in addition to the standard ATX mounting holes defined in
the ATX Specification, Version 2.03. The standoffs must be removable to maintain
backward-compatibility with boards that do not support Pentium® 4 processors. The four
(4) standoffs for the retention mechanism must be the same height as the standard ATX
board standoffs and compatible with 6-32 (x 1/2 inch-3/8 inch) pan-head or round-head
screws. It is the responsibility of the chassis vendor to supply the four (4) 6-32 screws with
the chassis.
Figure 3. ATX Chassis Mounting Holes for Pentium® 4 Processors
The direct chassis-attach solution has been tested at 30 g (11 ms trapezoidal pulse)
unpackaged system shock and 50 g (11 ms trapezoidal pulse) unpackaged board shock to
allow for differences in system structural designs. It is the responsibility of the chassis and
system designer to ensure that the chassis structure does not transfer greater than 50 g
shock to the board at a 30 g system input.

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2.3 Hardware
The screws should be 6-32 (x 1/2 inch-3/8 inch) pan-head or round-head screws (four each)
for the direct chassis-attach solution. The screw head must be less than 0.284 inch
diameter and less than 0.190 inch in height. It is the responsibility of the chassis vendor to
supply the four (4) 6-32 screws with the chassis.
3. Conclusion
ATX systems that support Pentium® 4 processors will require additional structural support
for large-mass heatsink solutions. The direct chassis-attach solution outlined in this design
guide identifies a single tested solution that will allow interchangeable ATX motherboards
and ATX chassis combinations. It is the responsibility of the supplier, OEM, and system
integrator to validate the final system design to ensure there is no damage to the system
components during shipping and handling.