There is a formula that uses the weight of the component and the surface area of the leads to predict whether or not the component will stay on the secondary side of the board without adhesive. Search the technet archives. I think Steve posted it in 97 or 98. I found it to be reliable. We did encounter a SMT relay that would not stay on the board. We tried adhesive, but it stretched during reflow. The result was disturbed joints. I don't recall what we did to resolve the problem. Hope you don't need to try. Guy Ramsey American Competitiveness Institute Senior Lab Technician / Instructor 610 362-1200 ext 107 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Lefebvre, Scott Sent: Wednesday, January 24, 2001 6:33 PM To: [log in to unmask] Subject: [TN] SMT components on BOT SIDE I need to place 16 QFP168 with 16mil pitch leads on the bottom side. I will am going to reflow both top and bottom. I feel that there should be enough surface tension to hold the parts onto the bottom, but I thought I would get some confirmation on this. Thanks Scott ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------