* Dave, * * Joe Belmonte & Phil Zarrow, "Advanced Surface-Mount Manufacturing Methods", Circuits Assembly, September 1996, page 36 * Formula for secondary side mounting * Weight of components (g) <30 Total pad mating area (sq. inches) Personally I find this too conservative. Bev Christian Nortel > ---------- > From: Dave Pick - process engineer[SMTP:[log in to unmask]] > Sent: Monday, March 23, 1998 10:38 AM > To: [log in to unmask] > Subject: [TN] Double Reflow: Component Weight vs. Pad Contact Area > Ratio > > I have read somewhere of a component weight to SMT lead contact area ratio > rule > for double sided reflow. This ratio would be the maximum component weight > to SMT > pad contact area that would allow surface tension to overcome gravity. If > the > weight to surface area ratio is over this number, the part would fall off. > Does > anyone know what this ratio is? > > ################################################################ > 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 web site (http://jefry.ipc.org/forum.htm) for additional > information. > For the technical support contact Dmitriy Sklyar at [log in to unmask] or > 847-509-9700 ext.311 > ################################################################ > ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################