In a message dated 10/13/2003 4:19:10 PM Central Standard Time,
pminmo@... writes:
What temperature does Ferric chloride need to be heated too for
improved etch times?
Phil:
I have not yet read others' opinions, but I use the nasty stuff (FeCl³) for
ALL my "one-each" non-PTH work, and HERE's your answer: Room temperature
"works", if kinda slowly. If you heat the stuff before use, 50°C will make it work
MUCH faster. I'd be afraid to go OVER that, not so much because it may-well
then exude noxious fumes, but because it'd melt the adhesive of the resists,
and then it'd eat EVERYTHING off your blank!
If you MUST use a microwave to warm the etchant, know this: The stuff is
VERY electrically-conductive, thus the first few mm. of it work as a "radio-freq.
shield", so only that first few mm. get hot! The container will quickly get
too hot to hold, so, "nuke" it for, say, 15 sec., then stop and "swish" it
around a bit, and nuke it another 15 sec. Do this for a total of a minute, until
you know "what works", and then increase the total time "per the math", if
necessary. BE VERY CAREFUL! If the container breaks open and spills that nasty
yellow stuff all down your wife's white kitchen-furniture and the insides of
HER microwave, I don't wanna be in the same State!
Jan Rowland
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