Paul, You ask some very valid questions and that's why I started this thread. In response to some of your questions: >could you enlighten me please: why the spot-bond , and what is the >detrimental effect occurring (?) with loose seat ? Small PTH components can float and tip during wave solder. >(upon loose cooling on crystalline formations ?) >Always thought the joint is actually too robust (as those with cavities >actually live longer), >but if you say this kind of effort is worth it , than 'm missing something . I don't think this is the issue unless you have a jerky machine that can knock components around, but then you have a lot bigger problem than stabilizing some components. >And how do you spot-bond actually (hand?)? Some do it by hand but we use an Asymtek X-X-Z machine along with some hand application. >Would a delayed heat (quartz tube just behind wave) postpone the solidus >just long enough to freeze in peace ? Again I don't believe this is the concern. >What would be the validated/qualified difference with and without (the >spot-bond)? Perfection of the product with no misaligned components. Just some thoughts, I sure others will have more. Ken Bloomquist Sr. Principal Process Engineer PRIMEX Aerospace Company P.O. Box 97009 Redmond, WA 98073-9709 http://www.primextech.com Ph: 425-885-5000 FAX: 425-882-5786 [log in to unmask] Northcon/2000, Chairman of the Board http://www.northcon.org Electronics Manufacturers Association (EMA), President http://www.ema-wa.org ############################################################## 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 ##############################################################