Hi Daan! We have successfully used HASL finished boards for the assemblies which contain area array components - But - I would recommend that you investigate the use of one of the new alternative board finishes (immersion tin, immersion silver, immersion gold/nickel) as a method of improving your assembly yields and eliminate soldering-ability issues. HASL has two disadvantages working against it as a surface finish for area array components; 1) the resulting HASL deposit on the pad is domed which can lead to placement issues; 2) typically HASL deposit thicknesses can vary greatly which can lead to soldering-ability issues. The advantage of the new alternative finishes is their inherent flatness. However, unless you live in the town of Perfect, the new alternative board finishes do not have the same solderability robustness and suffer quicker thermal degradation than a HASL board finish. We have migrated away from HASL board finishes to the new alternative board finishes for designs incorporating area array components and have been very satisfied with the results. We were just not getting the consistency we expected/needed for area array components with the HASL finish. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] "d. terstegge" <[log in to unmask]>@ipc.org> on 10/31/2002 06:00:21 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: [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 -----------------------------------------------------