Hi Keith: If you remember when AT&T and also Northern Telecom first came out with the SIR requirements, all PCBs were required to meet a SIR of 10000 megohms. It wasn't until AT&T started using water soluble hot air soldering leveling fluids and fusing fluids and they found out their HASL and fusing processes could not always meet this requirement that AT&T reduced the requirement to 3000 megohms even though the original supporting data suggested that 10000 megaohms was limit at which electromigration occurred. Bellcore reduced their requirement in 1984, following AT&Ts lead. Bellcore still requires that bare boards before applying solder mask meet the 10000 megaohm requirement. Some of your customers may be basing their requirements on the original AT&T specification. Give me a call sometime Keith Harry \\'''''// (o o) @----oOO---------(_)----------------@ | Harry O'Halloran | | DSC Communications Corporation | | 1000 Coit Road | | Plano, TX 75075-5813 | | Phone: (214) 519-3916 | | [log in to unmask] | @--------------------------oOO------@ | __ | __ | | | | | ooO Ooo ______________________________ Reply Separator _________________________________ Subject: SIR and SEC Author: [log in to unmask] at SMTPLINK Date: 3/7/96 12:29 PM I am interested in finding out if many of the board shops, or OEM's subscribed to Technet are seeing an requirement for SEC and SIR significantly tighter than the current Bellcore requirement. ie SEC.......1 micro gramme per sq. cm. NaCl equivelant SIR.......3000 megohms after HASL I have seen requests almost an order of magnitude tighter for both parameters and am wondering if this in response to an industry trend or just isolated cases. I am interested in finding out where our industry is heading, in this regard, and if any of the subscribers could suggest why a customer may need such tight controls. Keith Lumley, RexCan Circuits