Ron, Ted, Earl & others, For more information on buried capacitance, please access www.hadco.com and click on the "Technology" button and then the "BC Design" button (www.hadco.com/bcdesign.htm). Follow the links through the various sections of the BC Design Guide. Both "BC-2000" and "EmCap" are copper clad core materials that can be used to create distributed capacitance power/ground core pairs. BC-2000 (.002" thick ply of glass/epoxy dielectric) has a nominal bulk capacitance of 500 picofarads per sq.in.; EmCap (.004" thickness of ceramic filled epoxy) has a nominal bulk capacitance of 2.7 nanofarads per sq.in. At least 16 PWB fabricators are licensed to build boards using BC-2000 material. EmCap material will be similarly licensed. Please feel free to contact me off-line for further discussions. Dave Wolf, HADCO Field Engineer 612/893-1466 [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: [TN] Buried Capacitance Author: "Edwards; Ted A (AZ75)" <[log in to unmask]> at SMTPLink-Hadco Date: 7/31/98 11:21 AM Saw a presentation on it when they were Zycon, of course now they are HADCO The presentation showed 5 patents: 5079069 5155655 5161086 5261153 As I remember it; it is a sheet capacitance only. I think there are design implications as it I believe adds two layers to the board. Perhaps someone from there could give a summary on the TechNet . ---------- From: [log in to unmask] To: [log in to unmask] Subject: [TN] Buried Capacitance Date: Friday, July 31, 1998 7:05AM Buried capacitance material is available from many major laminate, core, and prepreg suppliers. There is a patent (number unknown to me) assigned to the process and material. Several Zycon engineering personnel were responsible for this invention. One is currently with Praegetzer as an engineering executive (name also unknown to me) and provides technical information about this material's use. Simply, the material is a thin laminate with specified dielectric thicknesses providing the required capacitance in impedance controlled printed circuitry. At the design level, engineers and designers may select the desired capacitance and design in the material. No special considerations are necessary but for unique design needs. This is true both at the design and fabrication level. Earl Moon ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################