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 -----------------------------------------------------