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Reference: viscosity, hardness

Terms for the Potting and Encapsulation Industry

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  A chemical additive which speeds up the rate of a chemical reaction and thereby reduces the gel time and cure time. Another term is promoter.


 The property of forming a steady or firm attachment.

Adhesive Failure

 The failure at the bond line between a substrate and an adhesive; the adhesive separating entirely from the substrate.


 The change in properties of a material with time under specific conditions.

Ambient Temperature

 The temperature of the surrounding environment.

Arc Resistance

 The time required for an arc to establish a conductive path in a material.

"B" Stage

 The intermediate stage during the curing process when the material has gelled but is not fully cured.

Bond Strength

 A measure of force or pressure required to separate a layer of material from its base.

Breakdown Voltage

 The voltage at which the insulation between two conductors will break down. See Dielectric Strength.

Burning Rate

 A term describing the tendency of materials to burn at different temperatures.


 To form plastic objects by pouring a fluid system into an open mold.


 A material which initiates and/or accelerates a chemical reaction but normally does not enter into the reaction.


 A unit of viscosity (with water as the standard) for indicating the fluidity or flow property of a liquid at room temperature.

Chemical Resistance

 A measure of the sensitivity of a material to attack or corrosion by a chemical material.

Classes Of Insulation

 Arbitrary temperature ratings based on composition and/or experience with a particular material.


 A finishing, protecting, or enclosing layer that seals a component from its immediate environment. See Dipping.


Coefficient Of Linear Thermal Expansion The fractional change in length of a material for a unit change in temperature. Measured in inch/inch/F or cm/cm/C.


 The internal affinity of a material to itself.

Cohesive Failure

 Failure within the adhesive under a stress, resulting in a broken bond with all adherent surfaces still covered with adhesive.

Compressive Strength

 A measure of the resistance of a material to a crushing load. Measured in pounds/square inch or megapascals.

Conductivity (Electrical)

 The reciprocal of volume resistivity. Conductance of a unit cube of any material.


 A compound resulting from the chemical reaction of two chemically different monomers with each other.


 Reacting together large molecules to change the physical properties of material.  Cross-linking involves formation of a three dimensional molecular network with thermosetting resins.

Cure Cycle

 The time and temperature necessary for a material to reach most of its optimum properties.

Cure Time

 The time for reacting thermosetting plastic or rubber composition to reach certain properties. For materials which react under the conditions of mixing, the start of reaction is the time of initial exposure to the conditions necessary for reaction to occur.

Curing Agent (Hardener)

 A cross-linking agent that reacts with a resin to form a copolymer.

Curing Temperature

 The temperature at which a material cross-links or cures.



 The weight per unit volume of a material. Measured in pounds/gallon, or kilograms/liter. Specific gravity is the density in kilograms/liter.

Dielectric Constant

 The ratio of the capacitance of a material to the capacitance of air.

Dielectric Strength

 The maximum electrical voltage which an insulating material can withstand without breakdown (conducting electricity). Expressed in volts/mil.


 The process of coating or impregnating of insulating materials by immersion into the uncured material.

Dissipation Factor

 The measure of the loss of power which takes place in virtually all dielectric materials, usually in the form of heat. It's expressed as the ratio of the resistive (loss) component of the current to the capacitive component of current and is equal to the tangent of the loss angle.


 The increase in length of a material when stress in tension. Measured as a percentage increase over the unstressed material.


 The enclosure of an electronic, electrical, or electromechanical device in a resin matrix. Most commonly, the embedding matrix is composed of a thermosetting polymer than can be converted from a liquid to a solid by heat, chemical reaction and/or a combination of these. The device is buried or encased in the liquid, which then forms a protective shell when the liquid hardens.


 Enclosing an article in a closed envelope of a material.

Epoxy Resins

 A specific type of chemical structure based on ethylene oxide.


 The amount of heat given off by a chemical reaction.


 See Adhesive Failure, Cohesive Failure


 An inert material added to a plastic to improve properties and/or decrease cost, most commonly limestone.

Flame Retardant

 The property of a material that extinguishes a flame once the source of heat has been removed.

Flexural Strength

 The strength of a material in bending.


 The propensity of a material to form a gas during cure.

Gel Time

 The time it will take a thermosetting material to become solid at a given temperature and mass.

Glass Transition Temperature(Tg)

 The temperature at which cured resins undergo a change from a glassy state to a softer more rubbery state.




  A material or mixture of substances added to a plastic composition which cross links another material, typically a polymer. See Curing Agent.


 Resistance of a material to deformation by indentation. See Shore Hardness.

Heat Deflection Temperature

HTD - The temperature at which a standard test bar will deflect 0.010" under a static load of 264 psi. A method to approximate Tg.


 A term replacing cycles-per-second as an indication of frequency. Abbreviated Hz.

Impact Strength

 The ability to withstand shock loading; or, work required to fracture under shock loading a specified test specimen in a specified manner. See IZOD Impact Strength.


 To fill the voids of a material with a compound.


 Material having a high resistance to the flow of electric current.

Izod Impact Strength

 The amount of force necessary to fracture a notched piece of plastic with a hammer type impact. Measured in foot pounds/inch of notch.

Lap Shear Strength

 A measure of adhesive strength when placed between two metal coupons and pulled in a tensile mode.


meter-mix-dispense equipment.  A dispensing machine that meters the proper amount of resin to hardener, mixes the two together and dispenses the mixture in to the unit to be potted.

Mixing Ratio

 The optimum amount of resin and hardener that gives the desired properties.

Modulus Of Elasticity

 The measure of stress to strain in a material that is elastically deformed. 

Moisture Absorption

 The amount of water a material will absorb under certain conditions.

Moisture Resistance

 The ability of a material to resist degradation from moisture in the air or when immersed in water.



 Composed of matter or chemicals of hydrocarbon origin.


 A high viscosity material that resists flowing on a vertical surface.


 A coloring agent.


 Highly polymeric materials that deform under stress and temperature. See Thermoset and Thermoplastic.


 To unite chemically two or more monomers of polymers of the same kind to form a molecule with higher molecular weight.

Post Cure

 Additional time/heat cycles to which a cured thermosetting plastic is subjected in order to enhance the properties.

Pot Life

 The amount of time a mixed material may be easily used at a specific temperature. It Is usually measured as the time it takes for a material to double in viscosity.


 The process where an insulating material is poured into a container and the container remains as an integral part of the unit.

Pressure Gellation

 A process for molding in which the shrinkage is minimized by forcing the material under pressure into the mold and gelling it in stages.


 See Accelerator

Release Agent

 A chemical agent used to prevent a material from adhering to a surface such as a mold.


 An organic substance of natural or synthetic origin characterized by being polymeric in structure.


 The ability of a material to resist passage of electric current through itself or on its surface.

Set Time

 See Gel Time

Shelf Life

 The amount of time a material may remain useable in its original containers.

Shore Hardness

 A method of determining the hardness of a material using a pointed gauge. Shore A and 00 and 000 is used to measure soft materials and Shore D is used to measure harder materials. See Hardness cross reference for comparison between type of Shore hardness.


 Polymeric materials composed of molecules of silicon and oxygen.


 A liquid substance which dissolves other substances.

Specific Gravity

 Metric measurement of Density, abbreviated Sp.G. See Density.


 Any material on whose surface an adhesive is spread for bonding or coating.

Surface Resistivity

 The resistance of a material to the flow of electric current over its surface. Measured in ohms/centimeter.


Tensile Shear Strength

 See Lap Shear Strength.

Tensile Strength

 The ultimate pulling force required to break a material. Measured in pounds/sq. Inch or megapascals.


 See Glass transition temperature

Thermal Conductivity

 A measure of a material's ability to conduct heat. Measured in BTU-inch/hours-square foot/F or calorie-centimeters/second-square centimeters/C.

Thermal Expansion

 See Coefficient of Linear Thermal Expansion.


 A plastic which will repeatedly flow under the application of heat and pressure.


 A plastic material that is capable of being changed into a non-melting or insoluble product by heat or chemical means.


 Describes materials that will not flow unless agitated or forced through an orifice. Shear thinning.


 False body. The property of a paste or fluid to thicken or set up to a paste or a semi-gel when allowed to stand. Agitation breaks it down but further standing will again permit a viscosity rise.


 A polymeric material that is formed by the use of an Isocyanate base chemical.

Vapor Degreasing

 A chemical method for cleaning surfaces of contaminants.


 A thin coating material that may be one or two package in nature and often contain solvents.


 A measure of the resistance of a fluid to flow or the internal friction within the body of fluid. Measured in Centipoises or Pascal seconds.

Volume Resistivity

 The resistance of a material to the flow of electric current through itself. Measured in ohms/centimeter.

Water Absorption

 The ratio of the weight of water absorbed by a material to the weight of the dry material.

Working Time

  (Work Life) See Pot Life


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Last Modified: March 28, 2015