I'd be more concerned about solderability of those pads than inductive
effects. The inductance of those little traces is, more than likely,
negligible. 

Mario Irigoyen

-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Toby
Carrier
Sent: Tuesday, April 13, 2010 2:37 PM
To: [log in to unmask]
Subject: [DC] SMD Pad Thermal Reliefs

Hi All,

I am reviewing a PCB (after just passing the CID exam Sunday), and have
found that there are no thermal reliefs on some surface mount components
that are attached to a conductive plane. I have told the designer of the
board to add them but they are worried that they will cause EMI problems do
to the inductance of the spokes. I do believe this to be an issue since we
are talking about a low current low frequency circuit (below 2MHz
fundamental and below 1.5A current), but they are still refusing to believe
my take on the matter. 

So what does the community think about this problem and have there been any
good documents published about thermal reliefs causing EMI problems in low
frequency applications?

Thanks,

Toby Carrier
IPC Desingers Council CID

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