Thermal & Converting Glossary

Thermal management and heat transfer technology terms and definitions. Click on a letter to jump to that section.

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ABS
(Acrylonitrile-Butadiene-Styrene) An amorphous thermoplastic polymer with high impact resistance, heat performance, and surface qualities.

Acrylic PSA
Acrylic based pressure sensitive adhesive. This type of adhesive has great chemical resistance and functions well in high temperature applications. It works best in long term adhesion applications.

Adhesive Tapes
Pressure Sensitive Adhesives (PSA), double and single–sided, acrylate, rubber or silicone based, carrier-free transfer adhesive or with carrier material, such as foam, non-wovens, foil or fabric.

AEM
(Eethylene Acrylic Elastomer ) synthetic or natural polymers with elastic qualities composed of ethylene and acrylic monomers.

Alkali Metal Heat Pipe
Heat pipe that uses alkali metal as working fluid. Alkali Metal Heat Pipes are typically used for high temperature (300°C to 2,000°C) applications.

AlSiC
Aluminum silicon carbide.

APG
Advanced pyrolytic graphite.

Axially-Grooved Heat Pipe
Heat pipe that uses extruded axial grooves in the internal wall as the wick material.

BEF
Brightness Enhancement Film

BLT
Bondline Thickness, typically used too describe the thermal interface material thickness between applied surfaces

BLU
Backlight Unit

Breathable PU film
Moisture-regulating germ barrier for wound care products.

Butt Cut
A type of rotary die cutting which works only with square corner parts. Parts are cut to the liner, leaving no gap between each part, and cut through liner for slug removal.

C4
Command, Control, Communications, Computers.

CAD
Computer-Aided-Design software programs.

Capillary Pumped Loop
Capillary action generated by fine porous wick material located only in the evaporator provides pressure head needed to circulate fluid through entire system. Vapor and liquid move in the same direction in a loop, rather than in counterflow, as in conventional heat pipes.

Carrier
The backing material that carries adhesives & separates adhesives coatings.

CCFL
Cold Cathode Fluorescent Lamp

Cd/m2
Candelas per square meter

Cellular materials
Cellular rubber and foam rubber, Polyethylene (XLPE), Polyimide (PI), Ethylene Propylene Diene Monomer (EPDM), Polyvinyl Chloride (PVC) and Polyurethane (PU) foams, silicone foam, blended cellular sponge/rubber formulations.

CFM
Cubic Feet per Minute - flow rate

Cleanroom
An isolated area with provisions to restrict contamination in the manufacturing process to preserve the quality of the manufactured product​. Cleanrooms are classified by the number of particles per cubic meter at a predetermined molecule measure. They can be anywhere from Class 1 to Room Air. Typical applications range from Medical wearables, devices, and disposables, to optical films, and precise electronics like smartphones.

Cleavage Strength
The force required to break the adhesive bond between adhesive and substrate when the pull is being applied to one end of the joint and the other end of the joint has no stress.

Closed-Cell Foam
A type of foam whose cell structure is made of uniform cells that retain their shape and prevent air from passing through. Closed-Cell Foam is great for insulating and tends to be more rigid and dense than open-cell foams.

CMM
Coordinate Measuring Machine

Cold Plate
A plate used to transfer heat and cool electronics. See Liquid Cold Plate.

Composite materials
Multi-layer insulation material, polyester film, non-woven polyester or chipboard combinations, chipboard-PET-chipboard.

COTS
Commercial Off The Shelf.

CP
Cold Plate

CR
(Chloroprene Rubber) A synthetic rubber with excellent flame resistance, good chemical stability, and usefulness over a wide temperature range.

CTE
Coefficient of Thermal Expansion.

CTE Matching
Coefficient of Thermal Expansion (CTE) matching involves harmonizing the materials of a heat source and heat sink to ensure that as temperature changes the devices expand and contract such that mechanical stresses are not induced to cause failure.

CVD
chemical vapor deposition.

DBEF
Dual Brightness Enhancement Film

DI Water
Deionized Water

Die
A tool usually made of metal with a design utilized to cut or shape materials.

Die Casting Mold
A closed vessel into which molten metal is injected under high speed and pressure.

Die Cutting
A manufacturing process of converting low-strength materials with a die (tool like a cookie cutter). Die cutting can be done with flatbed & rotary presses.

dP, ΔP, or delta P
Pressure Drop between two points in a flow path, typically before and after a flow resistance like a heat sink or liquid cold plate.

dT, ΔT, or delta T
Temperature difference between two points, typically between a hot spot and heat sink.

Dual Tabs
The use of two peel tabs, also known as pull tabs, placed on the top and bottom layer of the part. Dual tabs are a great way to improve assembly efficiencies and lower costs for the end user. Tabs can be designed into the part within the converting process or added on to the part manually.

EMC
ElectroMagnetic Control

EMI
ElectroMagnetic Interference

EGW
Ethylene Glycol based Water Solution

Elastomer
A material that is both viscous and elastic, making them compliant and maleable which is ideal for sealing and damping solutions.

Elastomers & rubber
Ethylene Propylene Diene Monomer (EPDM), Nitrile Butadiene Rubber (NBR, Buna-N), Natural Rubber (NR), Styrene-Butadiene Rubber (SBR), Neoprene Rubber (CR), Fluoroelastomers (FKM), Silicone (Viton), Masticated Rubber.

Elongation
The point at which a material stretches before it breaks. It is usually expressed as a percentage of the initial strength.

Embedded Heat Pipe
Heat pipe that is integrated into a solid material such as copper or aluminum to enhance the effective thermal conductivity of the solid material.

EMI/RFI shielding material
BOYD LECTROSHIELD - Fabric-Over-Foam (FOF), gasket material, electrically conductive adhesive tape and coated polyester fabric.

BOYD LECTROSHIELD - Conductive Foams

BOYD LECTROSHIELD - EMI Absorbers

Extruding
A high-volume manufacturing process to make long products by pushing a material, raw plastic or metal, through a die with a specific cross-section.

Fabric/fibre materials
Filter materials, reticulated foam, non-wovens, felts.

Non-woven: Inexpensive, disposable product with absorbent properties.

Silver fabrics: Germicidal, anti-microbial effect in wound care and cosmetic products.

FDA
Food and Drug Administration

FEM
Finite Element Method.

Fin Density
Fins per unit length

FKM
(Fluorocarbons/Fluoroelastomers) A fluorinated rubber with excellent flame and heat resistance.

Flatbed Die Cutting
A precision converting process that cuts a design by pressing a die into a sheet of material in a jaw like motion. This technique is commonly used in low-volume order because of low tooling costs. Production is slower in a flatbed that in a rotary press.

FLB
Fluid Lubricant Bearing

Flexible Heat Pipe
Heat pipe that includes a flexible section between the evaporator and condenser. The flexible section can be made of a bellows or other flexible structure.

Flux Density
Heat load per unit area (W/cm2).

Foam
A soft cellular material created by gas pockets in the base material. Typically made with compliant elastomers like rubber to create conformable seals or dampers.

FOD
Foreign Object Debris

FPI
Fins Per Inch - fin density

Fuel Cell
A system that combines hydrogen and oxygen to produce electricity.

Galvanic Corrosion
Metal corrosion when ions from one metal pass through an electrolytic fluid and corrodes a secondary metal. A common concern with Liquid Cooling Systems, especially those that contain both copper and aluminum.

Glass Transition Temperature
The temperature when an amorphous material, like rubber or plastic, transitions from a hard and semi-brittle to a more viscous, "glass-like" state.

Glycol/Water
A mixture of water and propylene glycol, an antifreeze that lowers the freezing point of water.

GN2
Gaseous nitrogen

Graded Wick Structure
A wick structure that has spatially varying wick properties.

Graphene
A single layer of graphite, pure carbon sheets. Graphite
One of the 3 versions of pure carbon. Molecules are arranged in sheets which allow for high planar conductivity compared to its through plane conductivity. Often used for heat spreading.

Head-Capacity
Pressure versus Flow

Heat-conducting material
TransTherm silicone and silicone free insulating foil, gap fillers, phase change material and adhesive tapes; flexible graphite solutions.

Heat Exchanger
A device built for efficient heat transfer from one medium such as air or liquid to another, whether the media are separated by a solid wall so that they never mix, or the media are in direct contact. Heat exchangers are typically used for enclosure cooling and can be of the following type: air-to-air, liquid-to-air, or liquid-to-liquid.

Heat Pipe
A device that transports heat through the evaporation and condensation of a working fluid (i.e., two-phase cooling). Heat pipes are devices that have an extremely high effective thermal conductivity, typically 10 to 10,000 times more conductive than solid materials.

Heat Pipe Heat Spreader
A plate that utilizes heat pipes to improve thermal conductivity and to move heat and cool electronics. Heat pipe spreaders are passive and increase the conductivity of the base material significantly.

Heat Sink
A heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using thermal contact (either direct or radiant). Heat sinks are used in a wide range of applications wherever efficient heat dissipation is required; major examples include refrigeration, heat engines, cooling electronic devices, and lasers.

Heat Spreader
A heat spreader is a device having high thermal conductivity to move heat from a concentrated or high heat flux source (high heat flow per unit area), to a heat exchanger with a larger cross sectional area, surface area and volume. Heat spreaders can be solid conductors like copper or pyrolytic graphite, or they can be a two-phase device like heat pipes and vapor chamber heat pipes.

Heat-Conducting Material
TransTherm silicone and silicone free insulating foil, gap fillers, phase change material and adhesive tapes; flexible graphite solutions.

Heavy Rail
High passenger volume multi-car subway system.

High-pressure gasket material
Non-asbestos fibre, Graphite, Aramid fibers with a nitrile binder

HX or HEX
Heat Exchanger

Hybrid Electric
Engine drives a generator for electric propulsion.

Hydrogels & Hydrocolloids
Skin-friendly adhesive for stoma products or electrodes.

Hydrophilic Polyurethane (PU) Foam
Wound care products for the optimizing of the wound environment.

I/O
Input/Output

ID
Inner Diameter, typically for O-Rings, Hoses, and Tubes.

IGBT
Insulated Gate Bipolar Transistor.

ISO
International Standards Organization

Isothermal Furnace Liner (IFL)
An annular heat pipe that is typically operating at high temperature (>300°C) to keep the hot zone of a furnace at uniform temperature or isothermal. IFLs typically utilize alkali metals such as cesium, potassium, sodium or NaK as the working fluid. Typical applications include crystal growth, temperature calibration, etc.

ITD
Initial Temperature Difference

ITO
Indium Tin Oxide

k-Core®.CFC
k-Core® with carbon fiber composite encapsulant.

Kiss Cut
A type of rotary die cuttings for all shapes. Parts are cut to a liner, leaving a small gap between each part, and cut through liner for slug removal. Finished parts are provided on a roll, since the liner is left untouched.

Laminating
The process of joining two or more materials utilizing pressure sensitive adhesives. Typically done by rolling materials together with an adhesive layer to bond them.

LAMPS
Light Airborne Multipurpose System.

LCD
Liquid Crystal Display

LCP
Liquid Crystal Panel

LCP
Liquid Cold Plate

LCS
Liquid Cooling System

Light Rail
Street level two-car transit rail systems.

Liner
A flexible material, usually plastic based, which carries a release agent. This is used to help protect the functional material or adhesive during transport and assembly and is ultimately removed prior to completing the final product.

Liquid Cold Plate
A plate that utilizes pumped liquid to move heat and cool electronics. Liquid cold plates are often machined and/or vacuum brazed with connectors for the liquid inlet/outlet ports.

Liquid Cooling System
A system used to remove heat by circulating a single-phase liquid using a pump and liquid-to-air heat exchanger. As opposed to air cooling, a single-phase liquid is used as the medium for transferring the heat. A water-based coolant is commonly used for cooling electronics, internal combustion engines in automobiles and large electrical generators.

LN2
Liquid Nitrogen

Loop Heat Pipe
A two-phase heat transfer device that uses capillary action to remove heat from a source and passively move it to a condenser or radiator. LHPs are similar to CPLs but have improved startup characteristics.

Medical Grade Adhesives
Adhesive tested for appropriate use in medical applications. These types of adhesives can range from skin contact tapes to one-time disposables, and repeat-use disposables.

Nanoscale Wick
A wick that is constructed of nano-sized structures for improved capillary pressure generation.

NPSH
Net Positive Suction Head. In reference to pump performance.

NPT
National Pipe Thread. Standard set of geometries used for pipe threads.

OCAs
Optically Clear Adhesives

OD
Outer Diameter, typically for O-Rings, Hoses, and Tubes

OEF
Optical Enhancement Film

OIT
Operator Interface Terminals

Open-Cell Foam
A type of foam whose cell structure is made of irregularly shaped cells linked together that allow air to fill the space. Open-cell foam is great for acoustic dampening and tends to be more light-weight and pliable than closed-cell foams.

Optically Clear Adhesive
(OCA) A specialized high transparent adhesive used to bond applications that require superior clarity.

O-Ring
An elastomeric seal with a circular "O" shaped cross section.

O-Ring materials
For more information on the various O-Ring compounds visit our O-Rings website here.

PA
(Nylon) A thermoplastic polyamide with excellent elasticity, tenacity, and abrasion resistance.

PAO
Polyalphaolefin

PC
(Polycarbonate) An amorphous thermoplastic polymer with excellent dimensional stability and high translucency.

PDP
Positive Displacement Pump

PE
(Polyethylene) A thermoplastic with good low-temperature characteristics.

Peel Strength
The strength of an adhesive adhering two substrates together.

Peel Tab
Also known as a pull tab. A small piece of liner designed to facilitate the easy removal of a part from its backing liner. Peel tabs are a great way to improve assembly efficiencies and lower costs for the end user. Tabs can be designed into the part within the converting process or added on to the part manually.

PET
Polyethylene Terephthalate. See Plastic.

PET
(Polyethylene Terephthalate) A thermoplastic polymer with excellent electrical insulating properties.

PG
Pyrolytic Graphite (PG)

PGS
Pyrolytic Graphite Sheets (PGS)

PGW
Propylene Glycol based Water Solution, typically used in liquid cooling and chiller applications.

PIA
Preferred Input Angle

PID
Proportional–Integral–Derivative - For Controllers

Plastic Deformation
Geometric deformation that is not reversed by the removal of the force that initially deflected the part. Plastics first undergo elastic deformation, which can be reversed, then plastic deformation which permenately changes the shape.

Plastics
A type of malleable large polymer molecules typically molded or extruded in a wide array of shapes.

PLC
Programmable Logic Controllers. Electronics that help control components like fans and pumps within complex systems like Liquid Cooling Systems.

PMMA
Polymethyl Methacrylate

Polyalphaolefin (PAO)
A highly purified ethylene derivative used as a cooling medium in liquid cooling systems.

Polyesters
A category of polymers with good strength and tenacity. Polyesters can be synthetic and organic.

Polymer
A large molecule or macromolecule with repeating sequences that can determine a broad range of chemical and phsysical characteristics, making them ideal for manufactured goods. See Plastics

Power Modules
Integrated modules of power switching devices.

PP
(Polypropylene) A thermoplastic polymer with high chemical resistance.

ppm/K
Thermal expansion in parts per million per K (e.g. micron/meter/Kelvin).

Pressure Sensitive Adhesive
An adhesive that bonds to a substrate upon contact. This type of adhesive cannot be repositioned once pressure is applied. A common type of adhesive that comes in a variety of peel and sheer strengths and formulated for specific substrates based on their surface energy.

PS
(Polystyrene) A thermoplastic polymer with excellent transparency and high tensile strength.

PSA
Pressure Sensitive Adhesive

PTFE
Polytetrafluoroethylene

PU
(Polyurethane) Great material for acoustical and shock absorption.

PVC
(Polyvinyl Chloride) A lightweight thermoplastic polymer with high chemical resistance and good insulation properties.

Pyro-shock
Shock caused by explosive devices for space deployment.

QDC
Quick Disconnect Couplings

Rafted
Mounting a device on shock absorbers to limit loading.

Rails
Thermal mass or masses at the edge of thermal cores or spreaders.

Ram Air
Increasing ambient pressure by using airflow of a moving object or vehicle to ultimately improve the performance of a component or system. Used in turbine engines.

REDI
Ruggedized Enhanced Design Implementation

Release Liner
A coated sheet that prevents a sticky substrate from adhering until the adhesive needs to be applied.

Remote Dissipation
Moving heat from a concentrated heat source to a location where that heat can be dissipated and managed more effectively.

RoHS
Restriction of Hazardous Substances

Rotary Die Cutting
A precision converting process that cuts a design using a cylindrical die on a rotary press. This technique is commonly used in high-volume orders because of high speed, and high accuracy. Great for multilayered products.

RTD
Resistance Temperature Detectors, Thermocouples

SAE
Society of Automotive Engineers

Score Slitting
The process of partially cutting a substrate by using force to push a blade.

Shear Strength
The force required to break the adhesive bond between adhesive and substrate when the pull is parallel to the surface to which the adhesive was attached to.

SiC
Silicon Carbide device.

Silicone PSA
A silicone-based, pressure sensitive adhesive. This type of PSA has excellent high temperature use and chemical resistance.

Slitting
The process of cutting a roll of material into a specific width or into smaller rolls.

Socket
CPU/GPU Socket

SOLIMIDE®
A high-performance polyimide foam developed by NASA for the space shuttle program. SOLIMIDE® foam has an open-cell structure, and features lightweight, thermal, and acoustic properties.

Steel-Rule Die Cutting
A precision converting process that uses a flatbed die made from hard and sharp steel. Dies are made specifically for each part and used for shorter production runs compared to rotary die cutting.

STP
Standard Temperature and Pressure

Substrates
The base layer material on which other materials are applied to.

Surface Energy
The degree of pull or push force of a substrate’s surface exerts on another. The higher the surface energy, the greater the molecular attraction, which allows the adhesive to flow and create a stronger bond. The lower the surface energy, the weaker the attractive forces, which limits the adhesive from flowing and creates a weaker bond.

T/R Module
Transmitted/Receiver module for phased arrays.

Tack
A measurement of how quickly a bond is formed between a pressure sensitive adhesive and substrate under light pressure.

Tape Backing
A type of carrier that holds tape and protects adhesive from environment.

Tensile Strength
The force required to break the adhesive bond between adhesive and substrate when the pull is equal through out the entire joint and perpendicular to the surface which the adhesive was attached to.

Thermal Circuit
Thermal resistance path between heat load and sink.

Thermal Plane
A plate to cool electronics.

Thermoplastics
Plastics and foils, such as: Acrylonitrile Butadiene Styrene (ABS), Hard Polyvinyl Chloride (HPVC), Polyethylene (PE), Polycarbonate (PC), Polyamide (PA), Polyethylene Terephthalate (PET), Polymethyl Methacrylate (PMMA), Polyoxymethylene (POM), Polypropylene (PP), Polystyrene (PS), Polytetrafluoroethylene (PTFE), Polyurethane (PU), Polyimide (PI), Polyether Ether Ketone (PEEK), Polyethylene Naphthalate (PEN).

Thermosetting plastics
Phenolic resin paper laminate, fabric-base laminate, polyester glass mat, vulcanized fibre.

Thermosyphon/Thermosiphon
A heat pipe that relies on gravitational forces to return the liquid back to the evaporator. Thermosiphons typically have no wick.

Thin Vapor Chamber
A vapor chamber with a thickness less than 3mm or 0.118 inches, basically the thickness of a credit card. See vapor chamber.

TIR
Total Internal Reflection

TMA
Tower Mounted Amplifier

Touch Temperature
Maximum allowable surface temperature that may come in contact with a user. See Aavid Genie Blog Post

TPE
(Thermoplastic elastomers) A mixed rubber composed of copolymers and polymers with both thermoplastic and elastomeric properties.

TPG
Thermally Annealed Pyrolytic Graphite (TPG)

Transfer Tapes
Tapes without backing material. Just adhesive on a liner.

TransTherm
TransTherm Catalog [PDF]

TransTherm Silicone & Silicone-Free Thermal Pads Material [PDF]

TTT k
Through-the-thickness conductivity.

Vapor Chamber
A flat or planar heat pipe that allows three-dimensional spreading of heat with an extremely high thermal conductivity. Vapor chambers are typically used as the base of a heat sink. Vapor chambers deliver higher thermal performance than a traditional heat sink by alleviating spreading resistance found in solid heat sink construction. Vapor chambers are typically constructed of stamped or machined plates with a hollow center for vapor flow.

TXV
Thermostatic Expansion Valve

Vapor Chamber
A flat or planar heat pipe that allows three-dimensional spreading of heat with an extremely high thermal conductivity. Vapor chambers are typically used as the base of a heat sink. Vapor chambers deliver higher thermal performance than a traditional heat sink by alleviating spreading resistance found in solid heat sink construction. Vapor chambers are typically constructed of stamped or machined plates with a hollow center for vapor flow.

Vapor Tower
A vapor tower heat pipe is a combination of a vapor chamber and vertical heat pipe. A vapor tower not only can spread heat like a vapor chamber in the x-y plane, but also transfers heat in the z-plane to heights much greater than 12mm or 0.5 inches.

Variable Conductance Heat Pipe (VCHP)
A variable conductance heat pipe is a heat pipe with a fixed charge of inert gas such as Argon or Helium used in applications requiring tight temperature control. Variable conductance heat pipes employ a large reservoir of inert non-condensable gas attached to the condensing section. The gas partially occupies the condenser as well, so changes in the pressure or temperature of the gas cause a change in its volume, allowing more or less condenser area to be active; this has a regulating effect on the operating temperature of the VCHP.

VME
Standard commercial card format - IEEE 1101.2.

W/m·K
SI units for conductivity Watts/(meter·Kelvin).

Water Jet
A converting tool, in which the cutter is commonly connected to a high-pressure water pump - water is ejected from a nozzle at high pressure, cutting through the material​. Waterjets are ideal for prototyping and can cut many types of materials.

Web/Webbing
Continuous rolls of thin, flat materials used in rotary converting

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