Loading ...
Sorry, an error occurred while loading the content.

Re: [casting] Re: Embedding electronics in resin

Expand Messages
  • Ed Hunt
    Let the blasted fire ants get in there........something has to do in them lil monsters......if nottin else, maybe it ll slow em down enuf to get em stepped on
    Message 1 of 16 , Jul 2, 2002
    • 0 Attachment
      Let the blasted fire ants get in there........something has to do in them
      lil monsters......if nottin else, maybe it'll slow em down enuf to get em
      stepped on !

      Cheers,
      elh
      ----- Original Message -----
      From: "bnglifecasting" <gainer@...>
      To: <casting@yahoogroups.com>
      Sent: Tuesday, July 02, 2002 8:59 AM
      Subject: [casting] Re: Embedding electronics in resin


      > --- In casting@y..., "workaholic_ro" <workaholic@c...> wrote:
      > > There is also some RTV crystal clear rubber (if you don't need to
      > > much hardness), I've seen an automotive voltage regulator embedded
      > in
      > > this sort of stuff but unfortunatelly I don't know any brand.
      >
      > There are silicone gels which are *very* soft, water clear,
      > and permanently sticky - like those kids' toys, but softer.
      > Soft enough that you can poke through with a soldering iron
      > and it'll self-heal afterwards. GE silicones RTV-6166, for
      > example.
      >
      > N.b. - when used in residential outdoor applications in the
      > south of the US, you need to work out some way of keeping
      > fire ants from absconding with the goo.
      >
      > --
      > Mike Gainer
      > http://www.bnglifecasting.com
      >
      >
      >
      > To unsubscribe from this group, send an email to:
      > casting-unsubscribe@yahoogroups.com
      >
      >
      > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
      >
      >
    • rdhornbaker
      Thanks to the replies thus far. As a newbie in this forum, my first posting was delayed a bit, so I ve learned a few things in the last couple days... Two
      Message 2 of 16 , Jul 2, 2002
      • 0 Attachment
        Thanks to the replies thus far. As a newbie in this forum, my
        first posting was delayed a bit, so I've learned a few things in the
        last couple days...

        Two factors seem to be key in selecting a resin for this application:
        1) Minimal shrinkage during curing
        2) A "coefficient of thermal expansion" (CTE) that matches the circuit
        board being encapsulated. In English, the cured resin needs to expand
        and contract at the same rate as the PCB during temperature changes,
        otherwise the stress will fracture the solder joints over time.

        I'd guess #1 has already been tackled, and it's just a matter of
        picking the right resin and curing method for the thickness being
        used.

        Is #2 a common issue in other applications? I'm not seeing CTE values
        in the resin specs, so I'm guessing not.
      • Elmer McKay
        Hi, I am an electronics technician by trade. I would imbed the circuit in RTV. Hang it into a plastic box using the wires to suspend it half way in. I have
        Message 3 of 16 , Jul 2, 2002
        • 0 Attachment
          Hi,

          I am an electronics technician by trade. I would imbed the circuit in
          RTV. Hang it into a plastic box using the wires to suspend it half way
          in. I have seen clear RTV's, but don't know where to get them at the
          present time. Unless there are LED's or other indicators on the PCB, I
          wouldn't think that you would need clear RTV, except for looks. Just be
          sure the wires coming from the board are color coded and that you have an
          accurate and up to date schematic with the correct wire color information.

          Elmer.

          At 05:15 AM 7/2/02, you wrote:
          >Message: 3
          > Date: Sat, 29 Jun 2002 19:04:07 -0000
          > From: "rdhornbaker" <Richard@...>
          >Subject: Embedding electronics in resin
          >
          >I'm curious whether it's possible to embed a small (functioning)
          >electronics device inside a solid block of resin. Has anyone here
          >done something of the sort?
          >
          >One point has been raised about shrinkage during curing, which would
          >stress / break solder joints. So, clearly I'd need a resin with
          >minimal shrinking...
          >
          >My circuit board is small - about 25mm x 60mm. To begin, the mold
          >would not be much bigger (say, 35mm x 70mm x 20mm thick). Is there a
          >crystal clear resin that fits this role?
          >
          >
          >Any other comments / tips / tricks on this idea?
          >
          >
          >
          >
        • anniepoo@netmagic.net
          I m assuming you re interested in making a gizmo with a circuit board buried in it, rather than simply protecting the electronics. If the latter, several
          Message 4 of 16 , Jul 2, 2002
          • 0 Attachment
            I'm assuming you're interested in making a gizmo with a circuit board
            buried in it, rather than simply protecting the electronics.

            If the latter, several people have suggested good methods for potting the board.

            If the former, it's probaby sufficient to put shrink wrap tubing round the board,
            shrink it on, and then put it in the resin. Any shrinkage taken up by the tubing.

            another simple alternative - smear some RTV caulk on it.
          • workaholic_ro
            ... embedded ... I just searched Gesilicones for a polyurethane RTV for concrete casting, I didn t find it but I discovered RTV12: Clear, two part, low
            Message 5 of 16 , Jul 2, 2002
            • 0 Attachment
              --- In casting@y..., "bnglifecasting" <gainer@b...> wrote:
              > --- In casting@y..., "workaholic_ro" <workaholic@c...> wrote:
              > > There is also some RTV crystal clear rubber (if you don't need to
              > > much hardness), I've seen an automotive voltage regulator
              embedded
              > in
              > > this sort of stuff but unfortunatelly I don't know any brand.
              >
              > There are silicone gels which are *very* soft, water clear,
              > and permanently sticky - like those kids' toys, but softer.
              > Soft enough that you can poke through with a soldering iron
              > and it'll self-heal afterwards. GE silicones RTV-6166, for
              > example.
              >

              I just searched Gesilicones for a polyurethane RTV for concrete
              casting, I didn't find it but I discovered RTV12:
              "Clear, two part, low viscosity, repairable, easy flow, condensation
              cure, silicone potting system for use where clarity is important.
              Protects high and low voltage electronic assemblies and connectors
              with primerless"

              Regards,
              work.
            • Steven Ericsson Zenith
              Hi, I am new to this group and to doing my own casting - looking to set up our own prototyping to build a few short run fascia projects for AV equipment
              Message 6 of 16 , Jul 2, 2002
              • 0 Attachment
                Hi,

                I am new to this group and to doing my own casting - looking to set up our
                own prototyping to build a few short run fascia projects for AV equipment
                (suggestions welcome).

                However, I'm curious about two things in this thread related to embedding
                electronic components - both thermal issues. First, I would expect the life
                span of the electrical components to significantly shorten unless the
                material in which they are embedded can appropriately dissipate heat and
                second, is there a risk of combustion?

                Regards,
                Steven


                > -----Original Message-----
                > From: anniepoo@... [mailto:anniepoo@...]
                > Sent: Tuesday, July 02, 2002 5:39 PM
                > To: casting@yahoogroups.com
                > Subject: Re: [casting] Re: Embedding electronics in resin
                >
                >
                > I'm assuming you're interested in making a gizmo with a circuit board
                > buried in it, rather than simply protecting the electronics.
                >
                > If the latter, several people have suggested good methods for
                > potting the board.
                >
                > If the former, it's probaby sufficient to put shrink wrap
                > tubing round the board,
                > shrink it on, and then put it in the resin. Any shrinkage
                > taken up by the tubing.
                >
                > another simple alternative - smear some RTV caulk on it.
                >
                >
                > To unsubscribe from this group, send an email to:
                > casting-unsubscribe@yahoogroups.com
                >
                >
                > Your use of Yahoo! Groups is subject to
                > http://docs.yahoo.com/info/terms/
                >
                >
              • mode101wpb
                I think there are limitations to what can and cannot be potted. Obviously you couldn t pot a PC chip due to heat dissipation or even a transformer, though the
                Message 7 of 16 , Jul 3, 2002
                • 0 Attachment
                  I think there are limitations to what can and cannot be potted.
                  Obviously you couldn't pot a PC chip due to heat dissipation or even
                  a transformer, though the windings themselves on coils/spools are
                  often potted in high heat epoxy.

                  Loctite has a array of potting compounds with specs.

                  http://www.loctite.com/pdf/potgasket.pdf


                  --- In casting@y..., Steven Ericsson Zenith <steven@p...> wrote:
                  > Hi,
                  >
                  > I am new to this group and to doing my own casting - looking to set
                  up our
                  > own prototyping to build a few short run fascia projects for AV
                  equipment
                  > (suggestions welcome).
                  >
                  > However, I'm curious about two things in this thread related to
                  embedding
                  > electronic components - both thermal issues. First, I would expect
                  the life
                  > span of the electrical components to significantly shorten unless
                  the
                  > material in which they are embedded can appropriately dissipate
                  heat and
                  > second, is there a risk of combustion?
                  >
                  > Regards,
                  > Steven

                  > >
                  > >
                • louis niederlander
                  ... The coefficient of thermal expansion is about 31 micro inches per inch. (this is for the circuit board itself- G10 epoxy fibreglas). Unless you are
                  Message 8 of 16 , Jul 3, 2002
                  • 0 Attachment
                    >2) A "coefficient of thermal expansion" (CTE) that matches the circuit
                    >board being encapsulated. In English, the cured resin needs to expand
                    >and contract at the same rate as the PCB during temperature changes,
                    >otherwise the stress will fracture the solder joints over time.

                    The coefficient of thermal expansion is about 31 micro inches per inch.
                    (this is for the circuit board itself- G10 epoxy fibreglas). Unless you are
                    putting this device under the hood of your car or on the space shuttle,
                    forget about it.

                    Regards,

                    Louis N



                    _________________________________________________________________
                    Chat with friends online, try MSN Messenger: http://messenger.msn.com
                  • louis niederlander
                    ... This is entirely dependent upon good electronic design. Potting compounds are not intended to be heat sinks. ... No (at least I ve never seen this happen
                    Message 9 of 16 , Jul 3, 2002
                    • 0 Attachment
                      >First, I would expect the life span of the electrical components to
                      > >significantly shorten unless the material in which they are embedded >can
                      >appropriately dissipate heat

                      This is entirely dependent upon good electronic design. Potting compounds
                      are not intended to be heat sinks.

                      >second, is there a risk of combustion?

                      No (at least I've never seen this happen in 30 years as an EE)

                      Regards,

                      Louis N


                      _________________________________________________________________
                      Send and receive Hotmail on your mobile device: http://mobile.msn.com
                    • Kevin Lafferty
                      A note of caution. If you decide to imbed the electronics in RTV be sure to use one specifically designed for potting of electronics. Most common brands of RTV
                      Message 10 of 16 , Jul 4, 2002
                      • 0 Attachment
                        A note of caution. If you decide to imbed the electronics in RTV be sure to
                        use one specifically designed for potting of electronics. Most common brands
                        of RTV (hardware store caulk, automotive gasket/adhesive, etc.) generate
                        acetic acid during the cure cycle. Over time the trapped acetic acid will
                        act upon the component leads and solder joints leading to early failure (add
                        vibration and the problem gets worse). There are many manufacturers for the
                        electronics potting RTVs (Dow, GE,�) and you can probably find the stuff at
                        most electronics suppliers (Allied, Newark, probably even Radio Shack).

                        Hope this helps.

                        Kevin Lafferty

                        -----Original Message-----
                        From: Elmer McKay [mailto:emckay70@...]
                        Sent: Tuesday, July 02, 2002 5:43 PM
                        To: casting@yahoogroups.com
                        Subject: Re: [casting]Embedding electronics in resin

                        Hi,

                        I am an electronics technician by trade. I would imbed the circuit in
                        RTV. Hang it into a plastic box using the wires to suspend it half way
                        in. I have seen clear RTV's, but don't know where to get them at the
                        present time. Unless there are LED's or other indicators on the PCB, I
                        wouldn't think that you would need clear RTV, except for looks. Just be
                        sure the wires coming from the board are color coded and that you have an
                        accurate and up to date schematic with the correct wire color information.

                        Elmer.

                        At 05:15 AM 7/2/02, you wrote:
                        >Message: 3
                        > Date: Sat, 29 Jun 2002 19:04:07 -0000
                        > From: "rdhornbaker" <Richard@...>
                        >Subject: Embedding electronics in resin
                        >
                        >I'm curious whether it's possible to embed a small (functioning)
                        >electronics device inside a solid block of resin. Has anyone here
                        >done something of the sort?
                        >
                        >One point has been raised about shrinkage during curing, which would
                        >stress / break solder joints. So, clearly I'd need a resin with
                        >minimal shrinking...
                        >
                        >My circuit board is small - about 25mm x 60mm. To begin, the mold
                        >would not be much bigger (say, 35mm x 70mm x 20mm thick). Is there a
                        >crystal clear resin that fits this role?
                        >
                        >
                        >Any other comments / tips / tricks on this idea?
                        >
                        >
                        >
                        >


                        To unsubscribe from this group, send an email to:
                        casting-unsubscribe@yahoogroups.com


                        Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
                        <http://docs.yahoo.com/info/terms/> .


                        [Non-text portions of this message have been removed]
                      • carldovis@aol.com
                        Animal telemetry companies have been embedding tracking devices with self curing dental tray resin and or self curing clear orthodontic resin for years. Call a
                        Message 11 of 16 , Jul 5, 2002
                        • 0 Attachment
                          Animal telemetry companies have been embedding tracking devices with self
                          curing dental tray resin and or self curing clear orthodontic resin for
                          years. Call a dental resin manufacturer or a dental supply house and try and
                          talk to someone who knows about auto polymerizing resin, the stuff they use
                          for denture relines and repairs. Altho the tray powder and liquid is probably
                          cheaper.
                        Your message has been successfully submitted and would be delivered to recipients shortly.