Cal, it sounds like it doesn't matter whether the via is plugged or tented. You just need it to be NON-solderable. (I'm in a similar situation). In other words, if the fabricator covers the via with solder mask, and doesn't etch the via opening, solder will not flow into the via, even if the via is not sealed closed, because there is nothing for the solder to wet to. So you need it neither plugged, filled, nor tented. How to convey this in the fab notes is difficult. I've resorted to giving the minimum mask dam requirements and let them figure out the best way to accomplish that. (I have had several fabricators tell me they despise covering the vias though) Ryan Grant -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Cal Driscoll Sent: Monday, August 30, 2004 8:39 AM To: [log in to unmask] Subject: Re: [TN] tented Via They reason I brought up tented vias as we are seeing an issue in the manufacturing process. The via is off a lead of a LCC. The solder needed is filling the via vs. soldering the lead. The new board vendor does not tent vias (as per their specs) and the tolerance is to tight to mask a dam. So currently we manually mask the via to produce cal -----Original Message----- From: Jeffrey Bush [mailto:[log in to unmask]] Sent: Monday, August 30, 2004 8:27 AM To: TechNet E-Mail Forum; Cal Driscoll Subject: RE: [TN] tented Via Of several, 2 main factors - application method and size of via. Curtain and screen applications tend to move more material into the via and provides a good base to remain there after image and develop. Spray coaters apply a more controlled coating that generally leave the hole free of mask. Each type of coating methodologies also have ranges of material application thickness that will also affect the plugging of the via. The second variable if the via size, which can vary by fabricator - some may drill at different sizes depending on pad-to-hole capabilities and processing needs. Smaller vias will plug more readily than larger. It is possible that each fabricator is using different application methods and/or via sizes. If plugging is important, I would make sure that this condition is stated on the drawing - ie. "All vias covered by mask to be plugged". This will allow the fabricator to apply the required processes to ensure plugging. Jeffrey Bush Director, Quality Assurance and Technical Support 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302-1890 Tel. 802.257.4571.21 Fax. 802.257.0011 [log in to unmask] http://www.vtcircuits.com -----Original Message----- From: Cal Driscoll [mailto:[log in to unmask]] Sent: Friday, August 27, 2004 1:15 PM To: [log in to unmask] Subject: [TN] tented Via Hello All- I am not a board fab person but would like to understand why some LPI masking processes can not tent vias (non filled). We have a board house that can tent vias with no issues. When we went to another board house the are unable to tent vias. Both shops are huge and have international locations. I would think the technology would be there to do this. thanks in advance, Cal www.ctdi.com --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 -----------------------------------------------------