Chan - I had great success working with Circuits DMA in the past. They're in Livonia Michigan. They have been plugging vias reliabally for years. They too had tried the dry film LPI combo - to no avail. The dry film seals a the ends of the barrels and produces a small gas chamber that can blow up later during assembly. Then, it tends to entrap flux and cleaners in the barrel. Later you get caustic and other reactions caused by that entrapment. Try CDMA - they plug the holes instead of tenting. I worked with Lance Field at 734 525-0600. Regards, Russ Steiner [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Chan, Marcelo Sent: Thursday, October 22, 1998 2:33 PM To: [log in to unmask] Subject: [TN] Plugged/tented vias We have tried different approaches to tenting/plugging vias for BGA and some backplane applications using LPI and screened SM with limited success...PWB vendors claim they could do it, but we are still looking for some one who could do this on 100% of the vias with no pin holes and it has to be done on both sides to prevent entrapment of cleaning solutions...the via sizes that we have in mind can have a finished hole diameter as large as 22 and as small as 13 mils...Can someone share their 'hands-on' experiences on this issue with me through Technet or even off-line? Thanks Marcelo Chan Lead Engineer - Advanced Manufacturing Technology Electronics Systems Sector, Harris Corp., FL ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################