To do this you need to understand how materials react to laser- absorb (material get removed), reflect (nothing happen), pass through (material is transparent to laser). Copper is a good reflector to IR (e.g. CO2) laser, so CO2 lasers won't do what you want. UV laser will be absorbed by both resin and copper with resin having a lower threshold energy. This means if the beam energy density is high enough to remove copper it will remove resin as well. So, with UV laser you need to hit JUST the copper and STOP the laser immediately after all the copper is removed - very, very difficult, if not impossible. I have seen green laser (532 nm) being used to remove copper and stop right at the resin interface, because resin is transparent to the green laser. However, the problem with transparency is the copper in the next layer down may get damaged. Maybe there are things that I have not think of, but hopefully this will spark some bright ideas in developing a good laser repair station. Mason Hu --------------------------------------------------------------------------------- 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 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 ---------------------------------------------------------------------------------