Hi Lee - two items to think about as you venture into double sided assembly: your reflow oven capabilities and the robustness of your pwb surface finish. Reflow ovens that have both top and bottom side heating provide some recipe flexibility to keep your "first pass and now bottom side" of the pwa from reaching reflow temperature. Surface tension will keep many components attached to the pwa so avoiding bottomside reflow isn't a requirement but it does keep the solder joint intermetallic thickness minimized. Secondly your "second pass and now top side" of the pwa has seen one thermal exposure - the surface finish (OSP, tin/lead, gold/nickel, etc.) needs to maintain its solderability so that successful soldering can be completed during the second pass. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] [log in to unmask] on 11/25/97 07:28:11 AM Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: David D Hillman/CedarRapids/Collins/Rockwell) Subject: [TN] Double sided assembly methods Gentlemen, I am looking for advise, checkpoints, pit falls, etc. on double sided PCB assembly methods. I have recently been informed by our engineering department that we will be advancing our board circuit densities by extending our bottom side component population from simple chip cap/resistors to active integrated components. I would greatly appreciate a few words from anyone presently producing high density, mixed technology, double sided boards, that can provide process insights. Lee McCuistion Manufacturing Engineer Cubix Corporation 2800 Lockheed Way Carson City, NV 89706 702-888-1000 x237 (voice) 702-888-1002 (fax) [log in to unmask] (e-mail) ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ############################################################## ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################