Electronics
Potting Epoxy
Technical Bulletin
Precision Epoxy Products
a division of :
Rock Art, Ltd.
4279 Midway Drive
Douglasville, Georgia 30134
Phone : (770) 489-0340
Product
Description: Electronics Potting Epoxies are used to
cast, insulate and contain electronic circuitry within a container or mounting box. The
idea is to encapsulate circuitry components, connection wiring and
miscellaneous hardware to insulate, contain and protect. Our 100% solids potting/casting
epoxies are non
conductive and achieve all three objectives well beyond what your
project may require. They also provide protection from exposure, thermal shock,
vibration, moisture, vandalism and spying eyes. With the wide range of
formulations available from Precision Epoxy, we can meet your needs regarding
liquid or solid state properties to suit your application. The Rigid
Casting Series Epoxies and the Deep Casting Series Epoxies are the most popular
for potting applications. Potting epoxies are available in clear, opaque or can
be pigmented to your choice of color ( see Color
Chart). De-air additives can be apart of the potting epoxy formulation to
allow for total air release without the need for torching to remove
surface air bubbles. This factor along with very low curing temperatures
protect encapsulated circuitry from any thermal damage during the casting
process. Our potting epoxies can handle extreme conditions once they are put
into service. This includes extreme hot or cold temperatures, freeze / thaw
cycles, impact resistance, chemical attack and submersion.
Coverage:
When casting or electronics potting, you will be dealing with cubic volume, one
gallon of epoxy mix will fill 231 cubic inches. For flat surface laminating,
coverage will be as follows :
| Description : |
Inch Depth : |
Square Feet per Gallon |
| Pour option 1 |
1/16 |
25.6 |
| Pour option 2 |
1/8 |
12.8 |
| Pour option 3 |
3/16 |
8.5 |
| Pour option 4 |
1/4 |
6.4 |
| Pour option 5 |
3/8 |
4.26 |
| Pour option 6 |
1/2 |
3.2 |
Surface
Preparation: Surfaces that are
being bonded to should be clean, dusted and free of grease, oil, wax
or silicone. A light blast of air into potting box will remove any unwanted
debris prior to the epoxy pour. Potting epoxy can be poured in multiple layers
as needed for circuitry placement situations or for very deep pours to avoid
exotherming conditions or problems. There will
be no delamination between pours and multiple pours will cure as one solid unit.
Complete all wiring, circuitry placement and layout prior to final encapsulation
pour.
Shop
set-up: A location for an epoxy mixing
shop will need to be set-up and ready for use as apart of the potting procedure.
The
mixing shop should be as close to the work area as possible to stage and
mix epoxies, to 
access application tools and to prepare and clean up as needed.
A
potting epoxy shop can easily be set-up as part of a regular work station. We
provide epoxy products in 5 gallon, 1 gallon, quart and pint packaging options
to suit your needs and volume requirements. Precision Epoxy also offers
accessory kits with all the items to complete your potting shop. For smaller
operations, we offer 400 ml and 800 ml beakers that are used for the entire
process. The beakers are calibrated allowing for the measuring of both epoxy
components at the proper mix ratio. Then with the special mixing blade attached
to your drill, the components can be stirred at the recommended 2 to 4 minutes
to mix
properly. Once mixed, the beaker's 'No Drip' pouring collar allows epoxy to be
poured into the potting box with extreme accuracy and zero mess. Should smaller
detailed and/or tedious applications be needed, we offer a calibrated 12 cc
syringe type liquid transfer pipette. The plastic tip is cut off as desired to
establish the size of the flow hole. Then the epoxy can be applied as a single
drop or inject as much epoxy as needed with pin point accuracy. Add a mix blade rest and drip
pan, an optional infrared thermometer, an optional candle warmer hot plate (used
with beakers to bring epoxy resin Part 'A' to a controlled temperature) and your
epoxy mixing shop is complete. For larger operations, we can package as needed
up to 55 gallon drums to suit the
needs of automated measuring and dispensing equipment found in assemble line
type operations. Precision Epoxy can assist in every detail from start to finish
to help with your complete electronics potting operation no matter how big
or small.
Measure:
Follow mix ratio as described on product's label. The mix ratio will be by
volume and it cannot be over emphasized that proper mix ratio be strictly
adhered to. Do Not alter the mix ratio for any reason. Should measuring
of components be done by weight instead of volume, contact Precision Epoxy for
the component weights of the product you are using. Calibrated measuring units
of various sizes are
available from Precision Epoxy.
Mixing:
Mix the measured Parts 'A' and 'B' components in a clean, dry container.
Components can be stirred until material is thoroughly blended using a flat stir stick for 6 minutes. This
is a primitive method and is not recommended for normal applications. Material
should be blended with an electric drill motor and the appropriate size mixing
blade for 2 to 4 minutes depending on your batch size. Proper mixing blades are
available from Precision Epoxy. If material is not mixed thoroughly, final pour
could have soft or sticky spots or a marbling appearance on the surface. Be sure
and scrape sides and bottom of mixing container to include all of both
components into the blend. Avoid whipping air into material while mixing.
Pouring:
Pour material into prepared potting box or mold in such a fashion as to aid in
leveling if possible. The potting epoxy will flow on it's own and fill in around
circuitry and/or hardware in most applications. Epoxy can be moved around, if
needed, with an appropriate size spatula to help with even distribution. Potting
box can also be rotated and/or gently pitched from side to side to move epoxy
around to coat all circuitry as needed. A dust cover is advisable if a perfect
finish is desired to keep dust or flying insects from ending up cured into the
top surface.
Torching:
Allow completed pour to sit several minutes to allow epoxy to migrate into all
the nooks and crannies of the circuitry layout. As the epoxy fills in, it will
push air bubbles out that will float to the surface. With a standard propane torch, wave the blue flame like a wand slightly above
the epoxy pour to break the surface tension and release air bubbles that have
migrated to the surface but have not yet released. Do not hold the torch in one spot
to long, keep it moving with even strokes. The epoxy is not flammable, however;
should flame touch the epoxy surface it can leave a discolored or sooty mark.
Should this happen, simply dip out the burn mark with your spreading tool and
continue. Any bugs or debris that might find their way into your pour can also
be dipped out in the same manner within your 'Open Time' window and the epoxy
will self level back smooth again. Air bubbles are also created when measuring
components, mixing components, pouring mixed epoxy and from elements created by
the surface you are pouring onto. Minimizing the sources of air will help with
clear coat pours, however, clear coat pours will always need torching. If you
are pouring with a pigmented epoxy color system or opaque system, the epoxy can be formulated
with de-air additives that will allow all entrained air to release on its own
and eliminate the need for torching.
Final:
There will be a point that you will
have to 'Leave It Alone' and let it cure. If flaws exist the next day, simply
cut, grind or sand them out and re-pour. Allow epoxy to cure the appropriate
amount of time as indicated on the product's label before handling. Curing times
can be accelerated by raising the ambient temperature around
the pour if needed.
The following are our
standard Epoxy Products suitable for Electronics Potting.
We also offer Modified Versions and Custom Formulations.
All mix ratios are by volume.
-
Rigid Casting Epoxy Series
is a fluid system used for
structural bonding, laminating, art casting, electronics potting, etc. The
RC Series epoxies are selected to suit
the application environment and temperature. They are available in thick or
thin viscosity versions to suit a wide range of applications and rates of
cure. These systems are non-conductive, high strength, high heat distortion,
self-leveling epoxies and are available in clear, opaque or pigmented versions.
-
RC-52 (mix ratio 1:1 / A:B)
Rigid Casting Epoxy - 52 is the 'Fast Cure' of the series for
specialized applications. This system has a pot life of ten minutes and
reaches handling strength in one hour at 77 degrees F.
-
RC-53 (mix ratio 2:1 / A:B)
Rigid Casting Epoxy - 53 is for use in applications requiring a rapid
cure or for use at lower application temperatures. This system has high
strength properties without being brittle, making it ideal for specialized
casting.
-
RC-55 (mix ratio 1:1 / A:B)
Rigid Casting Epoxy - 55 is the most widely used of the RC series. The 45
minute pot life at 75 degrees F seems to make it suitable for a wide range
of applications.
-
RC-57 (mix ratio 2:1 / A:B)
Rigid Casting Epoxy - 57 has the slowest rate of cure for use
at higher application temperatures or tedious applications where more open time would be
useful.
-
RC-190 (mix ratio 2:1 / A:B)
Rigid Casting Epoxy - 190 is a special 'Armor Plating'
formulation to satisfy special needs of the electronics potting industry.
This system is extremely hard and durable making it virtually impossible to
be broken down to reveal circuitry within the casting. Available in a thick
black color to further hide contents within the casting.
