If you ask the designer to (1) tape the kapton tape on a piece of clean glass (cleaned using IPA and DI, followed by IPA rinse and dry)(2) cut into small pieces of the size using knife - under microscope if it is necessary, (3) put the piece on to the PWB at desired location using tweezers with proper ESD protection/with ionized gas blow on his hands. I am sure you will never, ever see the same mistake again from the whole design group (the words get around very very quickly ;-). My 1.92 cents. Joyce Koo Materials Researcher - Materials Interconnect Lab Research In Motion Limited Office: (519) 888-7465 79945 Mobile: (226) 220-4760 -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: Tuesday, December 20, 2011 1:39 PM To: Joyce Koo; TechNet E-Mail Forum Subject: RE: QFP center slug over signal vias Yeah, that was my first solution but unfortunately it is too small to put Kapton on reliably (.006" x .015"). I tried to get it die cut but could not get a quote. -----Original Message----- From: Joyce Koo [mailto:[log in to unmask]] Sent: Tuesday, December 20, 2011 10:32 AM To: 'TechNet E-Mail Forum'; Bavaro, Phillip @ MWG - TW Subject: RE: QFP center slug over signal vias Based on my book, solder mask is not consider as valid dielectric for signal. (Kapton tape would be). Joyce Koo Materials Researcher - Materials Interconnect Lab Research In Motion Limited Office: (519) 888-7465 79945 Mobile: (226) 220-4760 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro Sent: Tuesday, December 20, 2011 1:26 PM To: [log in to unmask] Subject: [TN] QFP center slug over signal vias We found an existing design which has a device (QFP with center slug) that has too small of a center slug pad on the PWB. Within the corresponding area where the center slug pad should have been, the designer put some signal vias. Therefore the only thing preventing the signal via from shorting out to the center slug (ground) is the solder mask. No failures to date have been reported, even after a 20g vibe test. Is this a violation of J-STD-001 or perhaps IPC-2221 -6.3.4 regarding minimum electrical spacing? ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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