In a message dated 98-05-11 17:41:39 EDT, you write: << Just a question. I have been having problems getting my CMI unit to read copper thickness consistently. It has typically been reading low. For instance, the meter will show .0005 to .0006 of copper on a standard .042 thru hole but a section of the same hole shows .0012. The meter reads fine to the provided standard. Has anyone else experienced this problem. I should note that the meter was just calibrated a few weeks ago so calibration should not be an issue. >> We have been using a CMI PTX-200 for years and have never seen the deviation you are talking about. We do see some drift (on the order of 0.03 mils typically but sometimes as much as 0.010 mils) and therefore we calibrate our PTX-200 unit every shift. Sources of deviation: 1. There is a setting on the unit to compensate for different copper thicknesses, but these only affect the reading by perhaps 0.05 mil. 2. Cold temperature can decrease the reading by roughly 0.15 mils. 3. The large inaccuracy you're talking about would make me suspect the cross section technique. Is this done in-house? If so, a sample submitted to a testing lab might show that the problem isn't with the CMI at all, but with the cross section technique. Which of the 2 numbers would you expect to get based on your plating times? Peter Blokhuis [log in to unmask] ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################