Although I've not made any type of scientific study on 
     cleaning of reflectors, I've been using Isopropyl Alcohol for 
     years with no obvious problems.  
     
          This is a case where an ounce of prevention is worth a pound 
     of cure.  Try to keep the inside of the printer as clean as 
     possible.  Don't introduce any unfiltered air.  Obviously, the 
     less you clean reflectors the better.  Gently wiping with a soft 
     cloth dampened with alcohol should suffice.  With non-collimated 
     exposure units (flood type reflectors) you would have to really 
     scratch or dent the reflector to cause any noticeable problems.  
     A collimated reflector is much more susceptible to damage, and 
     even a small scratch can be reproduced on the panel.
     
          You might try vacuuming the reflectors with a cleanroom type 
     vacuum using a soft bristle attachment.  Check with your 
     equipment supplier; they may have some specific recommendations
     
     Mark Dowding
     Multek, Inc
     Irvine CA
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______________________________ Reply Separator _________________________________
Subject: FAB: CLEANING EXPOSURE UNIT REFLECTORS
Author:  [log in to unmask] at INTERNET_GATEWAY
Date:    4/26/96 9:06 AM


Has anyone made a study on how to clean the UV exposure unit's reflectors 
in particular on non-collimated + soldermask exposure machines ?
What to do / not do, frequency of cleaning, pros and cons..
- From what we can see, some people are using alcohol iso to clean, but 
is it a good solution ? Won't it remove natural protection and enhance 
oxydation ?
- Isn't it more suitable to polish, if so with which product ?
We are very concerned because exposure time for Probimer 52 is rather 
long (over 120 seconds) on two BASF 60/75 (Probimer 330) and PEPR 2400 
(ED Resist) on a PC-130 and a BASF 60/75 using Gallium lamps.
     
Thank you in advance
Regards, Roland
     
     
Roland Jaquet         Technical Director 
Henri Jaquet SA       PCB manufacturer
Geneva Switzerland    Prototypes and small qties 
tel. xx41-22-794-7878 fx. xx41-22-794-3052 
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