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February, 2019


Heat


trapped inside electronics and not dissipated by design can lead


to premature component failure and costly repair/replacement. To move heat away from sensitive parts or heat producing areas heat sinks have been developed that absorb excess heat and transfer energy to cooling gases or liquids. To hold substantial amounts of heat energy, heat sinks are structured with a broad metallic base. Attached to the base are a series of thin rods or prongs which stick out and are designed to maximize the surface contact area with the cooling gases or liquids. This allows the heat  heat transfer process is often assisted with fans or pumps.


To keep heat sinks in place and ensure a good path to dissipate excess heat, thermally conductive adhesives are often used. They provide a bond that does not insulate heat like typical adhesives. These special adhesives are often created by suspending powdered materials which are highly thermally conductive in the adhesive formula. With a variety of materials   the powdered materials. Each choice has tradeoffs.


A material must conductivity while copper


may exceptional could be seem


conductive, making it a poor choice for use around electronics where circuits


thermal be


manufacturers may thermally


conductivity, shorted


select conductive while compounds with electrical or


certain others


misrouted. powdered choose


Some


ceramics which powdered metals


used which


insulating a


electrically desirable


offers moderate/high at


a but


choice it


is


low cost. Powdered because highly


due


thermal to


electrically adhesives


are and


example, Hernon Manufacturing, Inc.®, a manufacturer of adhesives and sealants in Sanford, FL., incorporates powdered metal compounds in some  of 0.808 for their Dissipator® 745, while insulating with a dialectic strength of 26.7. Higher (or lower) thermal conductivity is available via the Hernon Manufacturing custom formula development program that designs new 


resistance such as aluminum nitride. For


Hernon Manufacturing


offers


two


thermally


conductive


adhesives


under the family name Dissipator® with grade numbers 745 and 746. The adhesives are chemically


cured using an activator which triggers


crosslinking and hardening. Application is as simple as applying adhesive to Dissipator® 745 and 746          meaning they become less viscous when shaken or squeezed and both operate in a temperature range of -55°C to 150°C (-65°F to 300°F).


When materials are pressed together during bonding, excessive or uneven pressure can lead to areas where too much adhesive is squeezed out


from between the substrates. This results in diminished bonding


performance. Dissipator® 745 is self-shimming and creates a uniform layer  shimming property is accomplished by mixing in small glass beads and the resulting even layer ensures predictable and consistent dissipation of heat and electrical insulation.


While bonding heat sinks is by far the largest application for thermally conductive adhesives,


these they are also used for potting components to


ensure even heat distribution. Other applications include fabrication of printed circuit boards and adhering LEDs or encapsulating sensors. Heat sinks can also be attached using threaded fasteners, but


           combination of adhesives and mechanical fasteners.


Advantages of using thermally conductive adhesives include:


• Reduced cost and time over alternative fastening methods • Conducts heat through an adhesive bond • Diffuses stress across the entire bonded surface • Bonds using lightweight polymers • Resists vibrations and impacts • Can insulate electrically  • Strong thermal cycling tolerance • Self-shimming option


Dissipator® 745: o o o o


Thermally conductive adhesive Room temp. curing Fixture < 5 minutes


o Controlled gap o o o


Dissipator® 746: o o o o


Bonds electrical components to heat sinks Insulates electrically


Dialectic strength of 26.7 Self-shimming to 0.005 in. to 0.006 in.


Thermally conductive adhesive Room temp. curing Fixture < 5 minutes


Bonds electrical components to heat sinks


Contact Hernon Manufacturing with any questions you may have about


production needs!


HERNON MANUFACTURING, INC.® 888-724-4071  sales@HERNON.com HERNON.com


thermally conductive adhesives or to discuss any of your unique


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