In a message dated 3/10/2004 4:01:36 PM Pacific Standard Time, Chris.Cheng@xxxxxxxxxxxx writes: No real data/example, still speculation. You can't just say I've done it 35 years therefore it must be correct if you can't even tell me there is a single case where a properly stackup PCB without BC will fail ESD test and after adding BC it works. This is a simple yes or no answer, nothing proprietary about it. I am still waiting. **************** Chris: Two items follow. 1. Perhaps the explanation I offered was not explicit enough for you. The "50-60 different designs" I referred to had ESD susceptibilities and yes, some of them were not well layed out to start with; however, even well designed boards improved their margins of susceptibility using BC construction. 2. As for your "core power distribution case" and "discharge happens through your package," I agree that BC (or few if any other techniques) will correct a design that places PCB-mounted components in (ESD) harms way. None of my earlier comments implied that BC alone was a panacea for ESD problem correction. I do maintain that use of BC is an excellent tool for minimizing the disruptive effects of any high-frequency injection of common-mode voltage on a power distribution system (PDS). Since the electrical environment for operational circuits AND their interconnects which use power or ground as reference planes (as any good designer would) is formulated by the PDS, CMV bursts are mitigated to a substantial degree. Mike Michael L. Conn Owner/Principal Consultant Mikon Consulting Cell: (408)821-9843 *** Serving Your Needs with Technical Excellence *** ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu