Hi Peter! Let me redefine a misconception - if you are truly going to "age" a pwb sample then the aging method would produce either the same oxide conditions, the same intermetallic conditions or the combination of oxide/intermetallic conditions that the pwb sample would have after sitting in storage for X amount of time. Unfortunately surface finish oxidation doesn't behave well in accelerated conditioning - typically you force/produce oxide thicknesses/species which are not present under normal storage conditions. Intermetallic growth is better behaved and there have been some good data published showing those relationships. I recommend you look at two conditioning methods: the use of humidity and the use of temperature. Tin surface finishes tend to degrade quickly under humid conditions in terms oxide growth. The use of temperature will highlight intermetallic growth problems. Now what recipes to use? Many investigations have used 85C/85% RH as their humidity parameters for oxide growth - you get to pick the time. Many investigations use either 125C for 8 hours or 150C for 16 hours as their temperature parameters for intermetallic growth. Instead of expecting to "age" the surface finish, looking at your conditioning as attempting to determine the "robustness" of the surface finish for a set of conditions (you will be much happier in the long run). You will have to decide just how "robust" you want the coating. For example, are acceptable wetting balance values after 48 hours of 85/85 exposure robust enough for your manufacturing process to have high yields? Only you can determine that. The IPC Alternative Final Finishes task group, chaired by Denny Fritz of MacDermid, is in the final stages of issuing a report that attempts to answer the question " is there a time/temperature/humidity conditioning parameter set which can be used for a variety of finishes to predict robustness?" - the JSTD-003 committee intends to use the Alt Finish committee efforts to revise the current "steam aging" methodology. Hope this helps. Dave Hillman Rockwell Collins [log in to unmask] Peter Hefti <[log in to unmask]>@ipc.org> on 04/25/2002 02:29:50 AM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to Peter Hefti <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: [TN] Accelerated test for simulation of storage of PCBs with surface finish white tin Hello TechNet: We are searching for a method of accelerated aging of PCBs with surface finish in white tin (chemical tin). This method should be recognized , in order to simulate the storage of 6 or 12 month under normal conditions. (85/85/1d or 2d test ??) After such an accelerated test, the solderability will be tested by the wetting balance method. Thank you for your answer With best regards Peter Hefti --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------