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Tough-Seal 21 Guards Electrical Components!
Tough-Seal 21
has the service temperature of an epoxy and the flexibility common
to urethanes. It’s the best of both worlds. Tough-Seal is a hybrid
epoxy elastomer and as such, it possesses the resilience of an
elastomeric matrix but Tough-Seal sets to form epoxy domains seeded
throughout the cured polymer that boost thermal resistance. This
Interpenetrating Polymer Network, IPN, remains flexible but capable
of delivering superior thermal cycling and it does so without
the use of isocyanates and their associated health & safety issues
because Tough-Seal is not a urethane.
Tough-Seal
is superior to ordinary epoxy and urethane potting compounds.
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Potting compounds & encapsulants are specified
to flow over an electrical device and fill up a housing with a hardened
thermoset plastic to serve as an environmental barrier. Epoxy and
urethane materials are prevalent throughout industry because they
suitably withstand intrusive environmental moisture, salts and chemicals
that can attack sensitive electronics and cause shorts. Epoxies
are typically rigid materials with high service temperatures and
urethanes are more flexible with lower heat resistance. Ideally,
one would specify a flexible potting compound to maintain a seal
with the housing wall but elevated service temperatures degrade
urethanes. Ordinary epoxy materials can handle the high service
temperatures but they are vulnerable to pull back from the housing
in cold conditions. Pull back creates a gap that is readily exploited
by the aggressive environment. Tough-Seal won’t pull back!
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Key Polymer is ISO 9001
certified and has 45 years in the business of supplying specification
materials to the electronic industries.
 Visit
the Key Polymer website for a complete product list
Take
the Tough-Seal
Challenge Today!
Order an evaluation
kit and everything you need to perform a high quality engineering
evaluation is expedited to you including direct access to the consultants
on the technical service “Seal Team” at Key Polymer. Time
and time again, specifying engineers determine that Tough-Seal comes
out on top in side by side testing with your existing encapsulant.
See for yourself. Order
a kit today!
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Chemistry aside, Tough-Seal is a Guard Dog that
grips the wall in cold when others contract to expose a gap, yet
it won’t wilt under the heat. Tough-Seal picks up where urethanes
leave off & guards up to 300°F.
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| ZERO
TOLERANCE FOR STRESS |
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ZERO EMBEDMENT
STRESS: the stress that electrical
components are subjected to when they are embedded in the
potting compound. It is the principle cause of component failure
even when an impermeable seal to the environment is attained.
The sensitive components can be dislodged from their connections
when (1) the potting compound hardens from a liquid to a solid
and later when (2) the part is exposed to thermal cycling
and the persistent expansion and contraction of the encapsulant.
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ZERO SHRINK - ZERO STRESS:
Tough-Seal avoids initial embedment stress upon cure
because it has imperceptibly low shrinkage. Thermoset plastics have a slightly larger
volume in their freshly mixed liquid state than they possess in their hardened cured state.
This differential volume is manifest by shrinkage and is aggravated by the size of the
pour and the extent of the resulting exotherm. The higher service temperature traditional
epoxy system essentially squeezes the components that it is designed to protect right off
the board. More flexible urethane systems shrink less and are more compliant than typical
epoxies but they are not recommended for the service temperatures encountered in underthe-
hood automotive service. Moreover, as is indicated later, flexible urethane systems
become hard in the cold extremes of thermal cycles and they induce stress post-potting. The novel, hybridized nature
of Tough-Seal has zero shrinkage upon cure per ASTM
D2256 and it cures with little to no reaction exotherm
even in large pours. Tough-Seal doesn’t get hot
but it can take the heat... under-the-hood.
THERMAL CYCLING - ZERO
STRESS: Why does Tough-Seal have superior thermal cycling
characteristics? Uncharacteristic of standard epoxies and urethanes, the hardness of Tough-
Seal is not a function of temperature. The hardness of other potting compound chemistries
are strong functions of temperature and they definitely get harder as they get colder and
become softer as they are heated. In the graph below, the hardness of Tough-Seal is nearly
constant. Again expansion and contraction forces are eliminated and thus they do not act on
embedded circuitry.
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Tough-Seal
forms a tough seal,
but it is gentle on electrical
components because it does not
change as conditions do. It
thermal cycles like no other and
it guards electrical components.
Is your project nearly complete
with your launch date fast
approaching but you’re getting
hammered on environmental
testing with your existing
encapsulant? You thought the
hard part was over with all design
reviews signed off except the
potting compound selection and
now the specification of the
potting compound is the only
thing standing between you and
success. Your electronic design
is high tech, why not go with the
latest technology in polymer
encapsulation?
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