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Normal epoxy or polyester resins for potting?

Discussion in 'Electronic Basics' started by Emil Johnsen, Oct 4, 2004.

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  1. Emil Johnsen

    Emil Johnsen Guest

    I'v googled this but didn't come up with any useful information.

    Can normal (intended for use with fiberglass) epoxy or polyester resins be
    used for potting electronics?
     
  2. Epoxys are more usually used with carbon fibre they are several multiples of
    cost above polyester resins which are commonly used with glassfibre.

    Think potting compounds are generally epoxy to keep exothermic effects down,
    heat when curing, and shrinkage.

    Polyesters get hot whilst curing and in castings are built up to save the
    thing cracking or in extreme cases self igniting, er ,guess who put too much
    catalyst in ;-) Polys are not, without additives , very flexible and also
    shrink by up to 3 or 4 % .

    Heat also finds every dry joint in your board ...

    Adam





     
  3. Having said all above have potted a few things with poly resins, dont make a
    3" deep block of the stuff in one pour, if it needs to be deep do it in a
    few stages.

    Use a filler, it helps extend, bulk out the resin , and mitigate shrinkage
    and heat, aluminium powder or `micro balloons`, both commonly available from
    glass fibre suppliers. look for boat building suppliers rather athn a DIY
    store, the differnce in cost is fairly dramatic.

    HTH
    Adam
     
  4. Emil Johnsen

    Emil Johnsen Guest

    Polyesters get hot whilst curing and in castings are built up to save the
    I think that using less catalyst will help avoid the heat problem. It will
    take longer to cure, but end result will be the same. Atleast that is my
    limited experience from messing up the resin/catalyst ratio when making
    fiberglass parts with polyester.

    I'm concerned about effects from the resin being hard as most potting
    compounds are flexible. Will this be a problem?

    I was also concerned about chemical compatibility, ie. the resin disolving
    plastics used in IC packages or other components, but I guess this can not
    be a problem since you have used polyester.

    Any long term problems?

    Anyone else who has tried polyester resin for potting?
     
  5. bob hoffman

    bob hoffman Guest

    I have used Devcon 5 minute to pot connectors and several small modules.
    It doesn't seem to degrade plastics. The stuff is clear and doesn't
    contain any fillers.
     
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