Richard remember that tented vias provide a greater soldermask dam between land pads and those solder stealing vias. You want a minimum of 12 mils soldermask dam between a typical IC land pad and a typical (usually test) via. Dorothy Lush > ---------- > From: Richard Todd[SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum. > Sent: Thursday, August 16, 2001 10:16 AM > To: [log in to unmask] > Subject: Tenting of vias > > Our printed circuit board purchasing specification currently specifies > that, when required by design, the vias shall be tented with solder mask. > I am in the process of reviewing this specification for its continued > applicability and have some questions about the tenting of vias. We are > currently in the process of switching from an ENIG process to an OSP-based > finish. Our ENIG boards were not tented, should the OSP boards be tented > to reduce the possibility of oxidation occurring on the vias assuming that > most (if not all) of the OSP burns off during the reflow process? I think > that the vias should be plugged prior to tenting to eliminate the > possibility of entrapped liquids or gases in the vias, any thoughts? We > use a LPI solder mask (SMOBC process) and a dry film would not be > appropriate due to the fine pitch and small traces (4 on 4) on some of our > designs. What is the best process for tenting with a LPI solder mask? > I guess that my primary question is do we need to tent the vias at all on > an OSP finished board? We do not perform ICT testing so the vacuum issue > is not a concern. > > I apologize for all of these questions, but as you can see I am fairly > confused. > > Thank you in advance for any and all replies. > > R. Todd > Dataram Corporation > Ivyland, PA > > -------------------------------------------------------------------------- > ------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > ------- > --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------