Heat Transfer compounds, paste, adhesive and potting

Thermal transfer imageMost electronic components produce heat when in use. The unwanted heat has to be dissipated away from the components to maintain performance and avoid premature failure of the components or device.  The need for efficient transfer of heat has become a key design requirement as components continue to reduce in size and increase in power, this is particularly apparent with microchip processors, LED's and power packs.

Designs will vary but in essence all involve some form of heat sink to dissipate the heat away from the active components. It is the interface between the heat sink and component that calls for the use of thermal transfer compounds, without their use any air gaps that exist will act as an insulator and prevent heat escaping.

These transfer materials come in a wide variety of forms; liquid adhesives, pastes, gels, potting compounds, sheets, rolls, pads and sprays. They also utilise an equally large array of chemistries. Choice of material will be driven by a combination of factors including:

  • Thermal requirements
  • Manufacturing processes
  • Environmental operating conditions
  • Need for additional functionality

Measuring Thermal Conductivity

Heat can be transferred in 3 ways: Conduction, Convection, Radiation.  As an aid to thermal management we are primarily concerned with conduction of heat away from its source.  Conduction of heat relies on the transfer of thermal energy by the vibration of particles which have physical contact with each other.

Thermal conductivity can be measured in several ways. Three techniques are commonly used, in order of general usage these are:        

  • Lees disk method
  • Hot plate method
  • Laser flash method

ACC utilises the Lees disk method as this has been shown over many years to be probably, the most consistent and direct method of measurement.

The units of measurement used are; W/m K (watts per meter degree Kelvin)

Silicone based thermal transfer materials

Thermally conductive silicone elastomers can be formulated as RTV and heat cured adhesives, encapsulants and non-setting compounds. For detailed infomation see our thermally conductive product pages

 

ACC Silicones Ltd, Amber House, Showground Rd, Bridgwater, TA6 6AJ
Tel: +44 (0) 1278 411400 Fax: +44 (0) 1278 411444