Let me just send the image directly
Steve
On Wed, Feb 10, 2021, 1:43 PM Nutting, Phil <[log in to unmask]>
wrote:
> Steve,
>
>
>
> Here is what I encountered.
>
> This site is blocked due to content filtering.
>
> Sorry, photos.google.com has been blocked by your network administrator.
>
> Sigh!
>
> Phil Nutting | Senior Development Engineer | Lab: +1-978-224-4334 *|*
> Mobile: +1-978-828-8664
>
> 35 Congress Street *|* Salem, MA 01970 *|* U.S.A. *|* *www.excelitas.com*
> <http://www.excelitas.com/>
>
>
>
>
>
>
>
> *From:* Steve Gregory <[log in to unmask]>
> *Sent:* Wednesday, February 10, 2021 3:40 PM
> *To:* TechNet E-Mail Forum <[log in to unmask]>; Nutting, Phil <
> [log in to unmask]>
> *Subject:* Re: [TN] RTV Encapsulation of circuit boards
>
>
>
> *EXTERNAL EMAIL:* Use caution with replies, links and attachments.
>
>
>
> Hi Phil,
>
>
>
> We don't use RTV but we do encapsulate a printed circuit assembly in a
> box. It's a mixed technology assembly with SMT and through hole. This
> assembly is a relay board that goes into vehicle HVAC systems, (ie: farm
> equipment, construction equipment, trucking) that we pot with a 2-part
> polyurethane compound from Epic Resins called their S7144. Here's a photo
> of a failed one that I cut the top of the case of a failed relay just to
> look and see what I could see. I'll see if this google image works:
> https://photos.app.goo.gl/oQvHwCbEm9TBFYvn9
>
>
>
> Steve
>
>
>
> On Wed, Feb 10, 2021 at 1:14 PM Nutting, Phil <[log in to unmask]>
> wrote:
>
> Technetters,
>
> We build several power supplies that use RTV in place of dielectric oil
> for our high voltage multipliers. The RTV allows us to get the same output
> level in a smaller package than a similar design using the dielectric oil
> as the insulator. The proper process is to medial blast (lightly) the
> circuit boards, prime them and then encapsulate the boards in the RTV.
> Both the media blasting and priming can be very subjective processes. And
> both have process issues in our manufacturing group. Simply eliminating the
> media blasting and priming is not a solution as the RTV will not bond to
> the boards and ultimately creating the potential for arcing to ground.
>
> Ideally potting a small box makes a disposable assembly, so the bonding
> quality and thermal size change of the RTV is not an issue. We use between
> 20 and 100 pounds of RTV per potted assembly. Disposal or repair of failed
> units is expensive.
>
> I am looking for folks that use RTV for encapsulation and what they use
> for a process to ensure good bonding between the RTV and circuit boards.
>
> Phil Nutting | Senior Development Engineer | Lab: +1-978-224-4334 |
> Mobile: +1-978-828-8664
> 35 Congress Street | Salem, MA 01970 | U.S.A. | www.excelitas.com<
> http://www.excelitas.com/>
>
> [cid:[log in to unmask]]
>
>
>
>
> --
>
> Steve Gregory
>
> Kimco Design and Manufacturing
>
> Process Engineer
>
> (208) 322-0500 Ext. -3133
>
> Cell Phone: (918) 706-2779
>
>
>
>
>
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