Joe Lee wrote:- >I am using microetch to treat surface prior to LPI and I would like to >know what will be the reasonable etch depth. Some one suggest me to use >pumice combine with microetch, Is that really necessary? By the way what >is pumice exactly? ( some kind slice?) Could you apply it manually and >how? Pumice is a naturally occuring volcanic rock containing glass which has abrasive qualities. When ground into powder and used in a cleaning machine, the pumice is kept in suspension by continuous stirring while being pumped into the cleaning chamber. There are two basic systems:- 1 Jet pumice which blasts the slurry onto the pwb surface at high pressure. 2 Brush pumice where the slurry is delivered at low pressure onto brushes which rotate and scrub the panel surface. The jet pumice machines tend to wear more quickly due to the abrasiveness of the pumice. The cleaned surface is rinsed and dried and is an ideal surface for LPI adhesion. Microetch is not necessary and would be detrimental to the pumice surface. There are proprietary pumice cleaners available with additives which can be very effective for cleaning small quantities by hand. It is difficult with a manual cleaning system to avoid copper oxidation because the surface is very active, and so a subsequent treatment in an acidic anti- tarnish solution may help. Another problem with manual cleaning is the residual pumice in small holes can block them. A pumice machine should have a high pressure rinse section to ensure all pumice is cleaned from the surface and the holes. Aluminium oxide is sometimes used as an alternative to pumice but I don't know of any benefits. Regards Paul Gould Teknacron Circuits Ltd [log in to unmask] Isle of Wight,UK *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************