DON: I suggest that you speak to your chemistry supplier about this. Immersion silver finishes contain an organic additive to preserve solderability. I don't know enough about the tin finishes to be certain, but I believe that they use similar organics. BOB: They do; e.g., Omikron's current offering uses the organic Ormecron. DON: Elevated temperatures (used to cure mask and nomenclature) degrade the final finish resulting in diminished shelf life and possibly reduced solderability. BOB: Agreed. With only 1 - 1.4 microns average immersion tin thickness it doesn't take much intermetalic growth to impact solderability. Most companies today apply immersion tin after the final thermal cycle for optimum material condition upon delivery. Bob Lazzara Circuit Connect, Inc. --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------