The basic Scotchcast™ epoxy resins products include flexible, semi flexible and rigid room-temperature curing and oven curing epoxy resin, some of which are then modified to create filled and thixotropic versions. Other subdivisions, based on temperature, class, colour and special formulations, complete the product line.
All Scotchcast epoxy resin products are formulated and produced for convenient and reliable use. Simple mixing ratios and preproportioned packaging allow for easy handling and mixing, and reduce errors on the production line.
Selecting Your Epoxy Resin
The Scotchcast™ epoxy resin most likely to succeed in an application can be selected through a process of elimination. Simply answer four basic questions (click over each for more information)
The availability of ovens.
If unavailable, or if their purchase cannot be justified by application, volume, or rate requirements, a room-temperature curing resin must be selected.
The application process.
From a production and engineering standpoint, oven cures are more versatile than room cures because they have long pot lives, short cure times and their viscosities can be lowered by warming.
The number of units to be processed.
Oven-curing resins are usually used in high-volume applications because they are less expensive than their room-curing counterparts. The expense of ovens is offset by a decrease in resin cost.
The mass of resin to be used per unit.
Room-curing resins rely heavily on the heat generated from their reaction for completion of cure. In large masses the resin could act as a heat insulator and cause the interior temperature to rise rapidly. If uncontrolled, this rise in temperature could exceed the maximum temperature some components can tolerate. A high exotherm could also cause the resin to crack or char. If a large mass of a roomtemperature curing resin must be used, the exotherm problem can be
overcome by curing the mass in layers and allowing each layer to cool before casting the next.
The handling and physical properties of the resin are important in answering this question. Consider the following:
are used in applications where very low viscosity is a prerequisite; for example, impregnating small or tightly wound coils and filling small voids. Filled systems
are used in applications where increased viscosity, reduced shrinkage, lower exotherm, increased thermal shock resistance, increased thermal conductivity or flame retardancy are needed.
Adding a filler always increases viscosity. If one or more of the properties cited are necessary but increased viscosity is not desirable, the viscosity increase can be nullified by warming the filled resin. A thixotropic
resin system is like a gel at rest but takes on the properties of a fluid when agitated. These systems are used in applications where “nonflow” is required, such as wet winding or encapsulation by dipping. A paste is an extremely high viscosity resin normally applied by spatula, caulking, buttering or troweling.
A resin rated in a specific temperature class is deemed capable of operating continuously at that temperature. The Association of Industrial Electrical Engineers (AIEE) denotes some of these temperature class ratings:
Class O = 90°C (194°F)
Class A = 105°C (221°F)
Class B = 130°C (266°F)
Class F = 155°C (311°F)
Class H = 180°C (356°F)
To answer this question, consider:
Are stress factors important? The flexible and semiflexible resin systems exert the least stress on components.
Is repairability desirable? Flexible systems are the easiest to repair.
Will the component be subjected to thermal or mechanical shock? If so, choose a flexible or semiflexible resin.
To what type of atmosphere will the component be exposed? Rigid epoxies, followed by room-curing epoxies, are usually the most resistant to solvents, chemicals, fuels and radiation.
What physical property requirements must the resin meet? Rigid systems possess the highest heat-distortion temperature and best physical properties.
The following selection guide
provide some additional information that may be used to determine the answers to the above four basic questions. Alternatively use the table below to help you.
A low-stress , highly moisture-resistant compound that cures at room temperature. This epoxy resin system offers long pot life , low viscosity , and is commonly used to coat printed circuit boards , pot connectors , and impregnate electrical and electronic components. Because of its low exotherm , it is also frequently specified for impregnating and encapsulating temperature sensitive units.
A thixotropic (heavy paste )
consistency that makes it useful for applications requiring a thick coating. a heavy
layer , applied by spatula , extrusion , buttering or trowelling , cures with minimum
sagging. The cured resin exhibits good physical properties , such as high thermal and
mechanical shock strength , strong adhesion , resistance to oil and fuel. It also exerts
little stress on sensitive components. Typical applications include filling , patching ,
caulking , holding , spot repairing , lead anchoring and insulating by buttering
end-turns of motor stator coils.
Suggested for insulating and
sealing motor-winding end turns and slot sections. At room temperature the resin has a
pot life of 1 to 1 1/2 hours (dependent on mass ) and cures in 24-48 hours. 3M Scotchcast
210 can be applied by spatula or by extrusion. It is useful for a variety of electrical
sealing , caulking , filling and patching applications.
An easy-to-use resin system
possessing medium viscosity and unique handling properties , a low toxicity potential and
is frequently used in applications requiring excellent thermal shock and mechanical shock
resistance. The resin °s low exotherm and good pot life allow the user
to mix substantial quantities at one time. High adhesion , low stress and low exotherm
also reduce the°effect of strain and temperature on
sensitive components that have been coated with this resin.
Characterized by outstanding
physical and electrical stability and superior resistance to moisture. Its low viscosity
and fine wetting properties allow complete impregnation of fine wires in coils.It is well
suited to impregnating , potting and encapsulating applications such as coils ,
transformers , modules and other electrical and electronic components.
Has permanent semiflexibility
, thermal shock and impact resistance , good electrical and adhesion properties. This
low-viscosity resin is well suited to a variety of general purpose , Class B
(130°C) applications. Its low viscosity and good wetting characteristics
allow complete impregnation of even small coils , and it has the mechanical strength and
flexibility needed for high-quality insulation of large castings , such as motors ,
transformers and coils.
High-temperature stability ,
good electrical and physical properties and low viscosity. This resin is suggested for
use in applications where adhesion , mechanical strength and good electrical properties
at high temperatures are needed.
Characterized by a high
temperature rating , outstanding physical andelectrical stability and superior resistance
to moisture. The Scotchcast Resin 280 system remains flexible even after prolonged heat
aging , while its low viscosity and fine wetting properties allow complete impregnation
of fine wires in coils. Scotchcast Resin 280 is well suited to impregnating , potting and
encapsulating applications that require superior electrical performance , maximum
resistance to moisture and thermal shock resistance. These include impregnation and
encapsulation of coils , transformers , strain-sensitive circuitry , modules and other
electrical and electronic components. Scotchcast Resin 280 can be cured at
65°C (150°F) and still exhibit excellent electrical
properties in applications where components require low temperature cures.
Widely used in dip coating
and wet winding applications where physical strength and excellent electrical properties
at elevated temperatures are required. Smooth and uniform coatings can be achieved with
minimal dripping or run-off during cure.
The thixotropic nature of
this product renders it readily applicable by dipping , extrusion or trowelling in
applications where resistance to running or sagging is a requirement. The properly cured
product exhibits permanent flexibility , good adhesion , good thermal and mechanical
shock resistance and good thermal conductivity. Typical examples of applications where
this product can be used are as a conformal coating for coils , transformers , motors ,
modules , electrical and electronic components or assemblies , and for buttering motor
Can be applied by dipping ,
spraying , extruding or troweling. As dipping resin , 282 provides exceptionally smooth
and uniform coatings with minimal run off or sag during cure and is suggested for those
applications requiring high temperature stability and permanent flexibility for thermal
and mechanical shock resistance. Examples are dipping and encapsulation of coils ,
transformers , motors , modules , strain-sensitive circuitry and other electrical and
A medium viscosity ,
semiflexible , two-part , heat-curing , brown pigmented , 100% solids epoxy resin
This general purpose resin system has built-in
flexibility, good adhesion, terminal shock and impact resistance, and stable electrical
and physical properties at 130°C (Class B) continuous operation. This
filled resin system is used where higher thermal conductivity and greater mechanical
strength are required (as compared to the unfilled Scotchcast 235 resin). It is
frequently used for motor encapsulation, transformer potting, and insulating other
electrical and electronic components
A medium viscosity ,
semiflexible , two-part , heat-curing , brown pigmented , 100% solids epoxy resin system.
Resin 243 is identical to 241, except it is unpigmented so it can be colored at any shade
desired. This general purpose resin system has built-in flexibility , good adhesion ,
terminal shock and impact resistance , and stable electrical and physical properties at
130°C (Class B ) continuous operation. This filled resin system is used
where higher thermal conductivity and greater mechanical strength are required (as
compared to the unfilled Scotchcast 235 resin ). It is frequently used for motor
encapsulation , transformer potting , and insulating other electrical and electronic
Widely used where physical
strength and excellent properties at elevated temperatures are required. Resin 251 meets
the requirements of MIL-I-16923A. An easy 1:1 mix ratio and good handling characteristics
have contributed to the product °s popularity. Warming this resin to
120°C (248°F) will lower its viscosity below 200
centipoise for maximum impregnating ability
Flame retardancy and
excellent shock resistance are key features of Resin 255. It meets flame retardancy
requirements of Fed. Std. 406, Method 2023.1 and MIL-I-16923G. It is rated for continuous
operation at 130°C. This resin also offers excellent thermal and
mechanical shock resistance. The product is suggested for use in potting and
encapsulating applications where shock resistance and flame retardancy are needed.
Characterized by high
temperature and electrical stability , and excellent retention of flexibility , even
after prolonged heat aging. It can be cured at low temperatures , but the optimum
properties are obtained with the higher temperature cure schedules. This resin should be
used instead of Scotchcast Resin 241 where greater mechanical strength , higher tensile
Polyurethane Resin 226 is used for a wide range of electrical and electronic potting and casting applications. For example, its low exotherm and low cure shrinkage, make possible the potting of small, heat-sensitive components, as well as the casting of large quantities of the resin at one time. And the very low viscosity of the product makes it possible to quickly fill and impregnate sand-filled modules.
OEM Insulation Tapes
3M™ Electrical Insulating Tapes are made from a broad range of backings and adhesives to meet the requirements of different applications and environments. Extensive quality control and testing, combined with accurate process controls, ensure that you get the highest quality electrical grade products.
EMC & RFI Products
Many of the world’s leading electronic and electrical manufacturers look to 3M for its exceptional technical and manufacturing experience in adhesive tape technology, from copper,aluminium & gold foil shielding tapes to EMI absorbers and sleeving, 3M has the solution for you .
Heat shrink tubing, from 3M, includes excellent quality thin, medium and thick walled heat shrink tubing as well as adhesive lined heat shrink tubing for a multitude of applications. 3M Heat shrink tubing offers excellent split and crack resistance and a very precise shrink ratio and recovery.
Aerosols, Sprays and Coatings
The Scotch® Spray product range consists of a number of different insulating, cleaning, protective and preventative maintenance sprays. These products should form a major part of any maintenance programme, from preventative action to repairing damage in all electrical and electronic environments.