I couldn't agree less. If your pad geometry is correct and if your stencil apertures are correct then there should be no problem. I have run quite happily without dams on 25 and 20 thou pitch. If you print solderpaste in 12 thou strips on 25 thou pitch then the 13 thou gap is more than ample with a 6 thou stencil. Regards Edward Brunker -----Original Message----- From: Ed Valentine [mailto:[log in to unmask]] Sent: Tuesday, February 08, 2000 4:45 PM To: [log in to unmask] Subject: Re: [TN] Solder mask dams between fine pitch parts Barbara - From a manufacturability viewpoint, you definitely want solder mask between fine pitch parts as a major factor in controlling bridging. In the '89-'90 timeframe, we ran many tests on in-house designed test boards that had both the "open window" and LPI mask between the fine pitch pads, even on the same part layout, using dummy components. The results were dramatic. Mask between the fine pitch pads made a huge difference in first pass yields on QFP's down to 16-mil pitch. We rarely ever had bridging. Ed Valentine Electronics Manufacturing Solutions Phone: (919) 270-5145 Fax: (919) 847-9971 www.ems-consulting.com [log in to unmask] ----- Original Message ----- From: Barbara Burcham <[log in to unmask]> To: <[log in to unmask]> Sent: Tuesday, February 08, 2000 10:04 AM Subject: [TN] Solder mask dams between fine pitch parts > What is the assembly industry take on the advisability of solder mask dams > between the pads on fine pitch parts - 25 mil? > To have or not to have? > What is the fabrication industry take on the maunfacturability of solder > mask dams between the pads on fine pitch parts - 25 mil? > To fab or not to fab? > > Barbara J. Burcham, CID > PCB Designer > Fairfield Industries > Sugar Land, TX 77478 > 281-275-7687 Work > 281-275-7550 Fax > [log in to unmask] > > ############################################################## > TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or > 847-509-9700 ext.5365 > ############################################################## ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ############################################################## ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################