Hi Dennis: Yes, we have done some studies on this subject. Copper dissolves faster from the surface and thru holes due to higher process temps and solubility rates in tin rich alloys. You could find some data in a paper we published in the Feb. issue of the Circuitree magazine. Please contact me if you need further info. Nimal Nimal Liyanage,Ph.D. Director of Business Development Metallic Resources Inc. 27 Shearwater Place, Newport Beach, CA 92660 949 854 7898 949 854 7175 fax 949 697 5826 mobile --------------------------------------------------- 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 -----------------------------------------------------