Epoxy Conductivity, Expansion & Contraction

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Discussion Overview

The discussion centers around the conductivity of epoxy, its expansion or contraction during curing, and its suitability for use in electronic applications, particularly for covering surface mount components on printed circuit boards.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested, Homework-related

Main Points Raised

  • One participant inquires about the conductivity of dry epoxy and whether it expands or contracts when curing, particularly in relation to filling gaps.
  • Another participant notes that epoxies vary widely in type and materials.
  • It is mentioned that most epoxies have poor thermal and electrical conductivity, but conductive metal-filled epoxies are available, as well as those with high thermal conductivity and low electrical conductivity for electronics.
  • One participant expresses a need for a non-conductive epoxy that does not expand or contract when set, citing concerns about potting materials damaging components on circuit boards.
  • Several participants provide links to suppliers and datasheets for potting compounds, suggesting resources for further exploration.
  • A later reply suggests that what the inquirer is looking for is referred to as a 'conformal coat'.

Areas of Agreement / Disagreement

Participants generally agree that there are various types of epoxy with differing properties, but there is no consensus on the specific behavior of epoxy in terms of expansion or contraction during curing, as well as its conductivity characteristics.

Contextual Notes

Limitations include the lack of specific data on the exact conductivity values of different epoxy types and the potential variability in expansion or contraction based on formulation and application conditions.

Who May Find This Useful

Individuals involved in electronics, particularly those working with surface mount components and seeking information on suitable epoxy materials for potting and coating applications.

yungman
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What is the conductivity of epoxy when dry? Also is there any expansion or contraction when epoxy cure? That is if you fill epoxy in a gap, would it pull or push the two side when dry?

Thanks
 
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Epoxy comes in many varied types and materials
 
Most epoxies have poor thermal and electrical conductivity and are also non-magnetic. However, you can get conductive metal-filled epoxies. You can also get epoxy with high thermal conductivity and low electrical conductivity which are used in electronics. And there is usually no expansion or contraction after curing. You may find what you need here:
http://www.mcmaster.com/#epoxies
 
Thanks for the reply. I definitely need non conductive type. I use it to cover electronic surface mount components on printed circuit board. I want the type that is opaque so people cannot see through. I need it to not expend or contract when set because I have seen potting materials pulling components apart when set and the circuit board stop working after potting.

Thanks for all your help as I don't know anything about epoxy.
 
Anyone please?
 
What you're looking for is called 'conformal coat'.
 
Last edited:

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