Glossary of Product Properties and Test Parameters

This glossary contains descriptions of key material properties, so that the user can better understand the products capabilities and limitations.

It is important to note that not all products are necessarily tested agains the same conditons, as they are not all necessarily relevant to either the product or the application

Group NameDescription
Application MethodChecking one of these application methods will filter by products that can be used for this application
Coefficient of Thermal Expansion (CTE)CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material. Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a system consists of an adhesive plus some other solid component.
Curing ScheduleCuring schedule is the time and temperature required for a mixed material to fully cure. While this applies to materials that cure with heat, there are also other materials that can be cured with UV. Even though some materials can cure on ambient temperatures, others will require elevated temperature conditions to properly cure. There are various curing schedules depending on the material type and application. For heat curing, the most common ones are Snap cure, Low temperature cure, Step cure and Staged cure. Recommended cure type, schedule, time and temperature can always be found on the Technical data sheets.
Dielectric ConstantDielectric Constant (k), commonly known as relative permittivity, is a number relating the ability of a material to carry alternating current to the ability of vacuum to carry alternating current. It determines the ability of an insulator to store electrical energy and is the ratio of electric permeability in vacuum against the electric permeability of a material. The lower the dielectric constant (κ) and dissipation factor, the less energy is absorbed from an electric field, making it a much better insulator. It is a dimensionless property that can be affected by various factors such as the
thickness uniformity of a material, insufficient contact between the sample and electrodes, water adsorption and contact resistance.
Dissipation FactorDissipation factor is commonly known as loss tangent or tan delta.

 It is a ratio of the loss index and the relative permittivity and it measures the inefficiency of an insulating material to maintain energy (that otherwise dissipates in the form of heat). The lower the factor, the better the insulation. It is the reciprocal of the quality factor and always refers to a specific temperature and frequency.
Flexural Modulus
Flexural Strength
Flow rateThe time it takes for the underfill to travel through a gap and onto a glass surface. Most results are for 1cm distance but always check the TDS for additional information.
Gel TimeGel time is the time it takes for a material to reach such a high viscosity (gel like) that it is no longer workable. It is usually measured for different temperature conditions and even though it does not refer to full cure it is advisable to never move or manipulate the material after it reached its gel time since it can lose its desired end properties.
HardnessHardness is a dimensionless quantity. There is no direct relationship between measurements in one scale and their equivalent in another scale or another hardness test.
Heat Sealing
Ionic Content
Melting Temperature
Metal Loading
Metallic Impurities
Particle Size
Post Mold Cure
Shear strength
Shelf LifeShelf life is the amount of time after manufacturing that a product is guaranteed to retain its properties. It differs vastly per product and it is based on temperature and storage conditions. The properties can be guaranteed for the temperature and time range indicated on the TDS since those are the ones tested to be the best for the product.
Spiral Flow
Storage (DMA) Modulus
Tensile ModulusTensile modulus is a mechanical property that measures the stiffness of an elastic material. It is the slope of stress / strain curve of a material under direct tensile loading. It can be used to predict the elongation or elastic deformation of an object as long as the stress is less than the tensile strength of the material. Elastic deformation is caused by stretching the bonds between atoms and the deformation can be reversed when the load is removed. Tensile modulus is affected by temperature and is an important engineering attribute since we generally want to keep elastic deformation as small as possible.
Tensile StrengthThe tensile strength of a material is the maximum amount of tensile stress that it can withstand while being stretched or pulled before failure. Some materials break very sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, experience some plastic deformation and possibly necking before fracture.
Water Extract DataWater Extract Data, 20hrs water boil