Yes:
     
        This application is a key factor creating a stable imaging 
     operation.  You need to determine exactly what data you want.  
     
     Are you using step wedges to control your process and monitoring with 
     a control chart?  
     
     Do you want to chart the energy that the equipment is putting out or 
     the energy that the resist receives?  If you are looking at what the 
     resist receives then you must include the photo tool.  Photo tools add 
     a very significant variation to the process.
     
     The data collection must be random.  If you have exposure equipment 
     where the lamp stays at full intensity while using a shutter to 
     control millijoules and the shutter action is not affected by use 
     (heat, lubrication) then the beginning of each shift is fine.  If the 
     lamp is instant on or reduced level and a less sophisticated shutter 
     mechanism then data must be taken when the equipment has not been 
     operated such as after shift change or lunch AND when the machine is 
     hot such as after 85 exposures of a 100 exposure cycle.  This could be 
     part of the exposure variation.
     
     Guy Willingham


______________________________ Reply Separator _________________________________
Subject: FAB:  SPC of printer
Author:  [log in to unmask] at corp
Date:    9/26/96 7:07 AM


TechNetters, here is another question about SPC.
     
Is anyone using SPC at the board image printing operation?  Our people 
here have been, at times and in an undisciplined way, been taking energy 
data from the printer.  The gauge is put at 9 points in a grid and energy 
delivered thus measured.  (These 9 measurements are made at approximately 
the same time, at the start of a shift, say.)  To me, this approach 
seems to lend itself to SPC.  Presumably, the measurements would be done 
on a regular schedule.
     
Anyone care to comment or correspond?   Lou Hart  Quality Assurance 
Compunetics 412-858-6117
     
     
.
     
*************************************************************************** 
* 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.        *
***************************************************************************