Ground Isolation - Intel Pentium 4 Design Manual

Layout Review Checklist
16.3.2

Ground Isolation

√
278
Recommendations
• Via to ground every ½ inches around edge
of isolation island, between RIMM
connectors and between RSL signals (from
St
MCH to 1 RIMM connector)
• Via between every signal within 100 mils of
the MCH edge and the RIMM connector
edge.
• No unconnected ground floods
• Ground isolation fills between serpentines
• Ground isolation not broken by C-tabs
• Ground isolation connects to the ground
pins in the middle of the RIMM connector.
• Ground isolation vias connect on all layers
and should NOT have thermal relieves.
• Ground pins in RIMM connector should
connect on all layers.
® ®
Intel Pentium 4 Processor / Intel
Reason/Impact
In channel Ideal:
Acceptable:
At end Ideal:
Acceptable:
* If 3/4 inch end of ground plane: shorten
ground plane by 1/4 inch to meet ½ inch
recommendation.
• To avoid discontinuity in ground planes.
• To avoid cross talk.
• To avoid discontinuity in the ground plane.
• Refer to Section 6.1.2.5.
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850 Chipset Family Platform Design Guide
R
5 inches
0 inches
25 inches
5 inches