Mike, Get in touch with CMI in Chicago - Elk Grove Village area. Think they are still in business. The principle is eddy current transmission though segmented conical probes. Think the probe tips used to be divided into 3 sections each, so you had 9 paths though the copper of a through hole. Worked pretty well in the early 90s to assure a mil of copper plating in holes. Saw it used at two large captive shops in the Midwest back then. Both are gone now - what's a captive board fabrication shop these days. Denny Fritz MacDermid, 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 ---------------------------------------------------------------------------------