Ciba's Probimer 52 is an all epoxy system. It is the only 100%
epoxy solder mask, that is photoimageable, currently available (to
my knowledge). 

While a 100% epoxy mask provides superior mechanical and
chemical resistance, it also has slower photo speed, poorer
resolution properties, and longer cure times.

The epoxy/acrylate systems have improved over the last several
years. They currently have mechanical and chemical resistance
properties that approach 100% epoxy systems. At the same time
they process easier than their epoxy counter parts. You can
achieve fast photo speed, high resolution, and short cure cycles.

I hope this helps you.

Bob Metcalf
Morton Electronic Materials 

>>> Terry Zhu <[log in to unmask]> 06/18/97 01:04am >>>
	I always thought LPI ink is mixed Epoxy with Acrylic resin.
Acrylic defines image ( free radical propagation unit by opening
double bond) and Epoxy give hardness and all kind of resistance
properties. I am truly not aware there are also all epoxy and all
acrylic LPI  around. Could anyone give me some information
about advantage and disadvantage among these different LPI
inks? Also I am wondering what photo reaction could be in all
epoxy system ? and if chemical resistance would be good
enough for all acrylic system? Sorry for being ignorant and all
input welcomed.

----------
From: 	[log in to unmask][SMTP:[log in to unmask]]
Sent: 	Monday, June 16, 1997 4:18 PM
To: 	[log in to unmask]
Subject: 	Re: Re[2]: LPISM Stripping

To clarify more, there is all epoxy LPISM, and there is also all
acrylic
LPISM, and there also is mixed epoxy/acrylic LPISM, and virtually
any coating
with SOME acrylic functionality can be stripped with strong alkali
and
solvent.

Pure epoxy anything, whether it is photo-imagable, or simply
thermal cure is
 more proof to stripping than butter coat, as butter coat contains
bromine,
which makes in liable to attack, if only slightly.

Hope this clarifies somewhat.

Rudy Sedlak
RD Chemical Company

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