Intel Pentium 4 Processor with 512-KB L2 Cache on 0.13 Micron Process Thermal Design Guidelines

Thermal Specifications

Intel

Pentium

4 Processor Thermal Design Guide 25

Figure 9. Heatsink Bottom Groove Dimensions

NOTES:

1. Applies to rectangular or cylindrical heatsink base

2. The groove depth (including the circle area) is 0.6 to 1.0 mm (0.025 to 0.040 inches)

3.3.3.3 Heatsink Preparation – Radial (Cylindrical) Geometry

For some heatsinks that have a radial geometry (see Figure 10), it may be necessary to locate the

center of the heatsink using features in the fin pattern.

For example, the 62-fin radial heatsink of the Intel reference design for the Pentium 4 processor in

the 478-pin package described in the note below, requires the following procedure:

1. Identify fin gap (a) as shown in Figure 10.

2. Count ¼ of the total amount of fin gaps in clockwise direction; identify fin gap (b).

3. Repeat for fin gap (c) and fin gap (d).

4. Scribe lines (a-c) and (b-d) across the core area of the radial heatsink.

5. Locate heatsink center at the intersection of lines (a-c) and (b-d).

6. Machine a groove 1 mm (0.040 inches) wide, 0.6 mm (0.025 inches) deep along line (o-a).

7. Locate the center for the circle area 1.3 mm (0.050 inches) off the heatsink centerline, along

line (o-a).

8. Machine the circle area 4.5 mm (0.180 inches) diameter, 0.6 mm (0.025 inches) deep to

accommodate the thermocouple and epoxy bead.

Note: This procedure takes into account the fact that the center of the IHS and the center of the heatsink

coincide for this particular design.