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 .
 

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