Obviously, I'm unworthy and incompetent (dangerous) as a metallurgist. Just hang around them too much. Also obvious, I have way too much time on my hands before starting my new contract (DFM and safety engineer for munitions and fuse making company - eehaw!). Safety in a bomb factory? Sure looking forward to this one. According to the new world soldering technology and technologists, intermetallics must form for a solder joint to be effected. This revelation has occurred over the past twenty or so years. Before that, Manko dictated that solder joints may be formed by joing to metal surfaces with a solder medium without requiring diffusion or intermetallic formation. I rather still like this as I work with surface scientists from time to time. Surface scientists regard a surface as being an objects area having no depth. At the same time, to analyze surface defects or quality conformity, they do not regard a surface as having been reached until a specified number of angstroms has been probed. An angstrom is a unit of length equal to one-ten-millionth of a millimeter, used for atomic measurements and wavelengths. I like what they say concerning intermetallic formations never reaching "depth" though, when they do, IMC thickness may be too much to promote reliable solder joints. What Manko was describing, I believe, was a condition wherein atomic mono-layers comprised the surface and that the solder "wetting" process was a function of not reaching farther than a surface scientist's definition of it. I just pose this to get a little something shaking during such trying times made up of much boredom punctuated with shear terror for some in times of terrible proportions. Earl --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------