Was it on this list or elsewhere? I forget now -- but somewhere I read that they like to do this for cell phones. By making the external layers connected to "GND", they can get better capacitive coupling to the user, which improves RF reception/transmission. Shawn Upton, KB1CKT Test Engineer Allegro MicroSystems, Inc [log in to unmask] 603.626.2429/fax: 603.641.5336 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Kenneth Wood Sent: Thursday, July 30, 2009 10:03 AM To: [log in to unmask] Subject: Re: [TN] Hashing-Out Hatching Actually that is the HDI method that is becoming more and more popular. Via-in-pad, internal routing and external GND planes. Ken --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------