Thermal Compound Dictionary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Bleed Out
The interface material migrates out from between two surfaces after a period of use.
Bond Line Thickness (BLT)
The thickness at which a thermal interface material (TIM) has the minimum thermal resistance. Thermal resistance will not change at thickness less than this value.
Dielectric Constant
A measure of a substance's ability to insulate charges from each other. If a material were to be used for strictly insulating purposes, it would be better to have a lower dielectric constant.
Dielectric Strength
A measure of the electrical strength of a material as an insulator. Dielectric strength is defined as the maximum voltage required to produce a dielectric breakdown through the material and is expressed as Volts per unit thickness.
Dissipation Factor
The reciprocal of the ratio between the insulating material's capacitive reactance to its resistance at a specified frequency. It measures the inefficiency of an insulating material.
Electrical Resistivity
An intrinsic property that quantifies how strongly a given material opposes the flow of electric current. A low resistivity indicates a material that readily allows the flow of electric current.
Kelvin (K)
The kelvin (abbreviation K), less commonly called the degree Kelvin (symbol, o K), is the Standard International (SI) unit of thermodynamic temperature. One kelvin is formally defined as 1/273.16 (3.6609 x 10 -3 ) of the freezing temperature of pure water (H 2 O). One Kelvin is the same change in temperature as one Centigrade.
Outgassing
Trapped gas that is released from a solid when it is heated or placed in a vacuum.
Pump Out
See Bleed Out.
Thermal Conductivity (TC)
A measurement of heat transfer from material 1 to material 2 through the thermal compound expressed in units of W/mK. The thicker the layer of thermal compound, the more influential thermal conductivity is. Examples for concept of scale: copper 385, aluminum 237, silicon 139, stainless steel 12.11 - 45.0, TIM 0.6-7.0, glass ~1.0, wood <0.4.
Thermal Interface Material (TIM)
Any material placed between two parts for the purpose of enhancing thermal coupling between the two parts. Synonyms: thermal compound, thermal grease, thermal gel, heat sink compound, CPU grease, thermal paste. See Nordson EFD thermal compound products.
Thermal Resistance (TR)
A measurement of temperature drop across an interface from material 1 to material 2 expressed as °C/W. Thermal compounds that have the best wetting and filler structure can have exceptionally low thermal resistance with moderate thermal conductivity. In low and medium thickness applications this lower thermal resistance can greatly enhance heat transfer beyond the capability of the highest bulky thermal conductivity TIM because thermal coupling is more efficient.
Watt (W)
A derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit is defined as 1 joule per second and can be used to express the rate of energy conversion or transfer with respect to time.
W/mK
Abbreviation for Watts per meter Kelvin (degrees). These are the units used to express thermal conductivity.
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