It's probably an old drawing...in those days most sn/pb was first electroplated and then reflowed (fused, which is actually, technically incorrect as the sn/pb had already been 'fused' in solution) using hot oil or some form of heated fluorohydrocarbon (not so much anymore with the green laws). The fused sn/pb will provide a flatter surface than HASL. Franklin -----Original Message----- From: Stadem, Richard [mailto:[log in to unmask]] Sent: Tuesday, September 20, 2005 7:52 AM To: [log in to unmask] Subject: [TN] Fused tin lead plating versus HASL Hi, folks I have a pwb fab drawing that calls out fused tin-lead plating or solder coating. I know that the solder coating is HASL, but what is fused tin/lead? My understanding is that it is a tin/lead coating that is applied to the bare pwb using a reflow oven process. Does this provide a flat surface of tin/lead? If my only choice of finish is tin/lead, which process is better in terms of flatness and solderability? I have a fine-pitch BGA that is going to be assembled on this pwb. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 -----------------------------------------------------