Intel® 820E Chipset

R

5.1.7.Testing Board Impedance

The Intel Printed Circuit Board (PCB) Test Methodology document (order# 298179-001) should be used to ensure boards are within the 28Ω +/- 10% requirement. This document can be found at http://developer.intel.com.

5.1.8.Board Impedance/Stack-up Summary

1.7628 cloth (1-ply, 0.007 inch when cured with 40% resin) is the most popular and highest-volume in PCB production today. This stack-up will make routing impossible.

Fab construction (4 layers)

Zo = 70 Ω ± 15%

Figure 99. 7 mil Stack-Up (Not Routable)

Component-side layer: 0.5 oz. Cu

7-mil prepreg

Ground layer 2: 1 oz. Cu

Not Routable

Total thickness

= 62 mils

 

 

 

Ground layer 3: 1 oz. Cu

 

7-mil prepreg

 

Solder-side layer 4: 0.5 oz. Cu

 

 

7mil_stackup

2.2116 cloth (1-ply, 0.0045 inch when cured with 53% resin) is the second-highest-volume cloth in production today. Because of the impedance and layout requirements of traces for Direct RDRAM, AGP 2.0, and the hub interface, this stack-up is recommended for Intel 820E chipset platform design.

Fab construction (4 layers)

Zo = 60 Ω ± 10%

Figure 100. 4.5 mil Stack-Up

Component-side layer: 0.5 oz. Cu

4.5-mil prepreg

Ground layer 2: 1 oz. Cu

~48-mil core

Total thickness = 62 mils

Ground layer 3: 1 oz. Cu

4.5-mil prepreg

Solder-side layer 4: 0.5 oz. Cu

4.5mil_stackup.vsd

Design Guide

181

Page 181
Image 181
Intel 820E manual Testing Board Impedance, Board Impedance/Stack-up Summary