[SI-LIST] Re: ESD is a low frequency event -really??
- From: Chris Cheng <Chris.Cheng@xxxxxxxxxxxx>
- To: "'MikonCons@xxxxxxx'" <MikonCons@xxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Wed, 10 Mar 2004 11:11:03 -0800
When it comes to BC, I have to agree with Simon.....
http://home.graffiti.net/3par/si1.jpg
Since you mentioned it is not a speculation, I presume you can give us some
real example of systems with proper stackup failing ESD test and when BC is
added it magically passed ? Care to share the information ?
I think what should be said is it has been massively demonstrated in SI-list
if what I refer to as "Common Sense Principle" is not followed, you will
need many painful fixes including BC.
-----Original Message-----
From: MikonCons@xxxxxxx [mailto:MikonCons@xxxxxxx]
Sent: Tuesday, March 09, 2004 1:55 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: ESD is a low frequency event -really??
In a message dated 3/8/2004 5:28:03 PM Pacific Standard Time,
Chris.Cheng@xxxxxxxxxxxx writes:
As for the BC comment, beside it being speculative, I can also make the top
and bottom reference planes to be ground and therefore don't need any plane
capacitance to provide the surface current to discharge.
I overlooked this comment in my response of a few moments ago. For
clarification, I too like to use reference planes on the available space on
both top and
bottom layers; however, my reference to BC to achieve tight high frequency
coupling between power and ground planes is far from speculative. The
broadband
coupling forces all reference voltages and planes within which any given IC
and its associated signals are operating to move in synchronism with any
applied
or induced common-mode voltage. Hence, the IC operating environment
pertubation is the best one can obtain under the conditions of an ESD
strike. Please
recall that I stated earlier that BC is only one element of several
complementary techniques that may be used in combination to meet a given
design
requirement.
There are many cases where, with careful and knowledgable layout (as Chris
has eloquently pointed out on many occasions), BC power/ground sandwiches
are
NOT required; however, the need for a low impedance, well-decoupled power
distribution system (PDS) has been massively demonstrated in many threads on
the SI
List. BC is one approach that works well in this regard. I generally use BC
construction in critical applications that justify the extra cost, which
amounts
to ~60% of my designs (for over 80 different companies). And, I use BC for a
few more reasons than most designers to obtain extra margin in specific
areas
that are critical to a given design.
Contrary to what one might infer, Chris and I are not in opposite camps, but
design in overlapping areas. For example, one of my (extreme) consulting
tasks
involved designing PCBs, enclosures, interconnects and a grounding and
shielding system for a compact, very lightweight application that required
the
system of three components to radiate over 60 dB less than FCC Class B
levels.
Mike
Michael L. Conn
Owner/Principal Consultant
Mikon Consulting
Cell: (408)821-9843
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