Long enough to provide some contact with the solder tip or wave so as to provide good thermal transfer into the work piece. Otherwise, the heat energy must pass first into the PWB then via convection (through the flux or solder itself) to the work piece. We used a DFM guide of .020" or about .5 mm as a minimum. Not so long that there is danger of the lead bending over to contact adjacent leads, or so long as to present a safety hazard, or so long as to pierce and render useless ESD protective packaging. IPC suggests 1.5 mm for leads that can safely be trimmed. Guy --- [log in to unmask] wrote: From: Ken Barton <[log in to unmask]> To: [log in to unmask] Subject: [TN] LEAD LENGTH Date: Wed, 2 Jun 2010 12:15:30 -0700 Hi Folks What is the preferred lead length protrusion on the secondary side for either wave or hand solder? Thanks, Ken Ken Barton Luma Technologies (425) 643-4000 x304 [log in to unmask] Visit us at www.lumatech.com ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------