IMO, once per day or even once per shift is not frequent enough.  
     There are too many variables that affect exposure; hold times 
     after lamination, artwork density, developer changes, just to 
     name a few.  We take our steps on every job.
     
     We use a glass to glass printing system (Byers) and have also run 
     into problems with step tabs.  Sometimes, depending on the 
     thickness of the panel and proximity of board image to the panel 
     edge, you just can't eliminate off contact.
     
     We trim our step tabs down to the smallest size possible, while 
     keeping the desired exposure range intact (for example, 5 to 10.  
     Our printing range is step 6 to 8).  This helps minimize off 
     contact.  We sometimes use a "dummy" panel for steps; it is 
     important however to have this panel coated at the same time as 
     the production lot.  I would not recommend putting steps outside 
     the glass.   There are several opinions about this, but I feel 
     better having the step against the panel.  C A Picards glass is 
     very optically clear; you would have to run tests to see if 
     inside/outside affects the step.
     
     Mark Dowding
     Multek, Irvine.
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: C A Picard Exposure Frames
Author:  [log in to unmask] at INTERNET_GATEWAY
Date:    10/1/96 5:19 PM


We have been running the Picard frames for a few months now and have found a 
problem running step tabs. When running PAC Glass we would put the step tabs 
inside the glass on opposite ends and have no problem with off contact. Using 
the Picard frames, we found putting step tabs inside the frame causes off 
contact. We have been putting the step tabs on the outside of the glass and we 
can read density but get no resolution. Has anyone done this and have you seen 
problems with this?
 I have heard of shops that run steps at the beginning of as shift only, using a
dummy panel. Is this true and how exposures control through out the day? 
Does anyone have any input on this, it would be helpful
     
Wayne Gitlitz
Elexsys International
[log in to unmask]
     
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