Glossary of Terms
for the Potting and Encapsulating Industry

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.
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.
Breakdown Voltage
The voltage at which the insulation between two conductors will break down.
A material which initiates and/or accelerates a chemical reaction but nor mally 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.
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.
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.
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.
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 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.
The amount of heat given off by a chemical reaction.
Flexural Strength
The strength of a material in bending.
Gel Time
The time it will take a thermosetting material to become solid at a given temperature and mass.
Glass Transition
The temperature at which cured resins undergo a change from a Temperature (Tg) glassy state to a softer more rubbery state.
Resistance of a material to deformation by indentation. See Shore Hardness.
Heat Deflection
The temperature at which a standard test bar will deflect 0.010" under a temperature static load of 264 psi.
A term replacing cycles-per-second as an indication of frequency. Abbreviated Hz.
To fill the voids of a material with a compound.
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 Mixing Equipment
A dispensing machine that mixes, meters, and dispenses the proper amount of resin and hardener.
Mixing Ratio
The optimum amount of resin and hardener that gives the desired proper ties.
Modulus of Elasticity
The measure of stress to strain in a material that is elastically deformed.
Post Cure
Additional time/heat cycles to which a cured thermosetting plastic is sub jected in order to enhance the properties.
Pot Life
The amount of time a mixed material may be easily used at a specific tem perature. 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.
See Accelerator.
Release Agent
A chemical agent used to prevent a material from adhering to a surface such as a mold.
The ability of a material to resist passage of electric current through itself or on its surface.
Shelf Life
The amount of time a material may remain usable in its original containers.
Shore Hardness
A method of determining the hardness of a material using a pointed gauge. Shore A is used to measure soft materials and Shore D is used to measure harder materials.
Specific Gravity
Metric measurement of Density, abbreviated s.g. See Density.
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 per square inch or megapascals.
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 pres sure.
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.
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 Centipoise or pascal seconds.
Volume Resistivity
The resistance of a material to the flow of electric current through itself. Measured in ohms/centimeter.

This data is for investigation and independent verification. While the information herein is believed to be correct, Solar Compounds Corporation makes no representation as to its accuracy. Solar Compounds Corporation shall in no event be responsible for any damages directly or indirectly resulting from the publication or use of or reliance upon data contained herein.