Sue, You have every right to be confused, as the chairman of the plating committee that put out the specification 4553, I have gone back and re-read the specs. The specs refer to thin silver and thick silver. My apologies for the poor choice of terminology, the intent was to differentiate between the Alpha Level product which could only produce a very thin coating and the rest of the Immersion silvers out there that could produce a thicker coating. So "thin" is a spec for Alpha level only and the "thick" is the spec for all other immersion silvers. For users not specifying Alpha Level the spec is: 5 uins minimum, typical 8uins-12uins. Thick silver would be silver at 20uins or higher. Thicker silver is unnecessary and may give rise to compromised solder joint strength. I am not sure that embrittlement is the main defect here, after all the Pb/free SAC 305 alloy contains 3% silver. George Milad (Chairman IPC Plating Committee) National Accounts Manager for Technology Uyemura International Corp (UIC) 249 Town Line Rd Southington CT 06489 [log in to unmask] Cell: (516) 901 3874 --------------------------------------------------- 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 -----------------------------------------------------