Hi Daan! If you have a HASL finish that is very flat it most likely means that all of the solder was blown off in the HASL process leaving only a very thin layer of solder which has converted itself into copper/tin intermetallic. The Cu/Sn intermetallic is nearly unsolderable unless you are using very aggressive flux chemistries. You could run a solderability test per JSTD-003 which should failure demonstrating the problem to your board fabricator. Now back to my Diet Coke and Snickers (standard issue TechNet breakfast). Dave "d. terstegge" <[log in to unmask]>@ipc.org> on 10/31/2002 08:31:52 AM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to "d. terstegge" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: Re: [TN] HASL process OK or not ? Hi Mike, Yes this was prior to assembly, it's not localised areas of bare copper but several pads having a dull appearence and a color somewhere between brown, green, and solder. There's no solder dome, it's very flat. Daan Terstegge Unclassified mail >>> [log in to unmask] 10/31/02 02:23pm >>> Was there Cu exposed on the bare PWB you inspected, prior to assembly / soldering? -----Original Message----- From: d. terstegge [mailto:[log in to unmask]] Sent: Thursday, October 31, 2002 6:00 AM To: [log in to unmask] Subject: [TN] HASL process OK or not ? Hi Technet, Yesterday I visited one of our bare board manufacturers and had a close look at their HASL-process. The reason for the visit was solderability problems on BGA-pads, which sometimes look thin and dull. Occasionally copper seems to be visible through the tinlead. In general I think this is a very professional boardshop, but (being not an expert) I don't know what to think about their HASL-process. I hope someone on this great forum is willing to give me some input on my findings, in terms of good or bad, or possibilities for improvement: Machine: Quicksilver SM, vertical HASL, 250 kg solderpot, no preheat Time between microetch (drying) and fluxing can be up to two hours Solder pot temperature set to 255 °C Leveling is done is such a way that the solder is as flat as possible, although the design of the airknives causes a big difference betweeen the two boardsides. With XRF we measured a thickness of only 0.4 microns on BGA-pads, with about 3 microns on similar pads on the other boardside. Water-based flux from an open tank, without any composition control, but tank is replaced every 24 hours. Solder is replaced every 6 months, but except for copper contamination no composition-check is ever done. When copper is above 0.3 % the dross is skimmed off to assure that copper content stays below 0.35 %. Throughput of the machine is about 700 panels per day. Daan Terstegge Thales Communications Unclassified mail Personal Website: http://www.smtinfo.net --------------------------------------------------- Technet Mail List provided as a free 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/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 1.8e 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/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 1.8e 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/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 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------