I have seen several references to "Pad etch" in micromachining literature - specifically relating to removal of a sacrificial oxide layer. I have asked several chamical suppliers and checked in several references to no avail (I believe it is a specialisat formulation (HF?) by Ashland, but can find no reference to it on their MSDS?). Can anyone help me with what it actually is & who supplies it? Best regards, Karen Smith MST consultant Coventry, UK _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp