This is common as you approach fine(r) lines. Image/etch fine line acuity can be compounded by weave transfer (or topology). It's better to use finer weaves at the outer (against copper) to remedy this issue. You'll find that chemical resistance is better with higher resin content also. (In case you ever do reprocessing or have high pH stripping solutions.) Groovy ______________________________ Reply Separator _________________________________ Subject: Unidentified subject! Author: [log in to unmask] at SMTPLINK-HADCO Date: 8/31/96 12:03 PM We have been facing dificulty in processing 4/4 mil,5/5mil ML boards.There has been excessive defects particularly seepage shorts in outer layer only.This seepage shorts we have further analysed and noticed seeping of COPPER and TIN plating. The copper thickness at the seeped location is only around 5 microns, indicating that seepage or lifting of photoresist is occuring during the end of the plating cycle. All these seepages are creating multiple shorts.Our observation is that it follows a definite pattern of the glass WEAVE TEXTURE.I am interested to know 1. any specific construction ie., specific glass styles to be used for fine lines. 2. any specs /ref., for acceptability of outer surface with respect to WEAVE TEXTURE. 3. any change in surface preparation wud improve (we have pumice scrubbing in our existing process.) 4.any checks exists to check photoresist adhesion .We use tape test, is this an acceptable test procedure. Presently we are using vacuum aided computer controlled hydraulic electrically heated presses.,press param is 2 cycle ,8'kiss 50psi,90'cure 300psi . *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************