The workers at a printed wiring board manufacturer use a mixture of
volatile solvents (e.g. MEK, toluene) to clean liquid photoimageable solder
masks (LPISM) inside the machines (Ichinose SMT-200 from Toshin Kogyo Co.,
and DP-2000 from Circuit Automation inc.)  used to apply the masks on the
boards and to clean off the masks on the screens and other instruments when
they must change the mask.  The masks are not cured when this task is
performed.  Workers perform this task manually using solvent soaked rags.
The workers' breathing air concentration of MEK and toluene is very high
while doing this task.  I was wondering if any of you know of a safer
solvent that I might recommend to this company.  Alternatively, is there
another way of applying the masks that would eliminate the use of cleaning
solvents?  To date, I have had suggestions from two LPISM manufacturers.
One of the suggested solvent mixture is even more toxic than the one
presently used!  The other suggestion I got is a safer solvent but from the
nature of the solvents (dibasic esters and glycol ethers) I suspect that it
will not evaporate fast enough...

Denis Begin, M.Sc.
Research Assistant
University of Montreal
Faculty of Medicine
Department of Occupational and Environmental Health
PO Box 6128, Main Station
Montreal (Quebec) H3C 3J7
Canada
Tel: 514-343-2170
Fax: 514-343-2200
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