Hi Lloyd,
We spray out of a can for all of our coatings 1B73, 1B31, and 1A33. Oh,
there's one more, MG Chemicals 422B...
But what are those dots? UV tracer behaving funny?
Steve
On Tue, Feb 28, 2017 at 4:27 PM, lduso - Diamond-MT.com <
[log in to unmask]> wrote:
> That dots look fine, good coating around the hole. We use EZ-peel from
> Caplugs by the way.
>
> Are you using a rattle can or mixing it yourself?
>
> On Feb 28, 2017 16:58, "Steve Gregory" <[log in to unmask]> wrote:
>
>> Hi Phil,
>>
>> We've been using Shercon KD Kwiky Dot Discs which are supposed to have an
>> acrylic adhesive:
>>
>> http://www.all-spec.com/Catalog/Adhesives-Sealants-Tapes/
>> Tapes/Dots-Discs/KD00312-45075
>>
>> Those aren't the ones you are using are they?
>>
>> Steve
>>
>> On Tue, Feb 28, 2017 at 2:35 PM, Nutting, Phil <
>> [log in to unmask]>
>> wrote:
>>
>> > With our acrylic conformal coating I noticed a blooming effect around
>> the
>> > masking tape dots. It turned out that the tape dots had changed from
>> > acrylic adhesive to silicon adhesive.
>> >
>> > Phil
>> >
>> > -----Original Message-----
>> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
>> > Sent: Tuesday, February 28, 2017 4:19 PM
>> > To: [log in to unmask]
>> > Subject: Re: [TN] Baking before conformal coating
>> >
>> > I don't know what the heck is going on here, but try these links!
>> >
>> > Arrrrrrrrrgh!
>> >
>> > http://stevezeva.homestead.com/Conformal_dark_spots.jpg
>> >
>> > http://stevezeva.homestead.com/Conformal_dark_spots_close.jpg
>> >
>> > http://stevezeva.homestead.com/Conformal_dark_spots_
>> > close_reflected_light.jpg
>> >
>> > Steve
>> >
>> > On Tue, Feb 28, 2017 at 2:14 PM, Steve Gregory <[log in to unmask]>
>> wrote:
>> >
>> > > Oh shoot, I sent thumbnail links! Here try these:
>> > >
>> > > http://stevezeva.homestead.com/Conformal_dark_spots.jpg
>> > > <http://stevezeva.homestead.com/Conformal_dark_spots_thumb.jpg>
>> > >
>> > > http://stevezeva.homestead.com/Conformal_dark_spots_close.jpg
>> > > <http://stevezeva.homestead.com/Conformal_dark_spots_close_thumb.jpg>
>> > >
>> > > http://stevezeva.homestead.com/Conformal_dark_spots_close_
>> > > reflected_light.jpg
>> > > <http://stevezeva.homestead.com/Conformal_dark_spots_
>> > close_reflected_light_thumb.jpg>
>> > >
>> > >
>> > > Steve
>> > >
>> > >
>> > > On Tue, Feb 28, 2017 at 2:07 PM, Steve Gregory <[log in to unmask]>
>> > wrote:
>> > >
>> > >> Hi Doug, Lloyd and everyone,
>> > >>
>> > >> Here are some photos:
>> > >>
>> > >> Area under UV light (BTW, that's my Ray-O-Vac pet pee-pee detector
>> light
>> > >> I bought at Walmart):
>> > >>
>> > >> http://stevezeva.homestead.com/Conformal_dark_spots_thumb.jpg
>> > >>
>> > >> Close-up of area under UV light:
>> > >>
>> > >> http://stevezeva.homestead.com/Conformal_dark_spots_close_thumb.jpg
>> > >>
>> > >> Close-up of the same area under reflected light:
>> > >>
>> > >> http://stevezeva.homestead.com/Conformal_dark_spots_close_
>> > >> reflected_light_thumb.jpg
>> > >>
>> > >> So you can see that the area is indeed coated. This is Humiseal
>> 1B73....
>> > >>
>> > >> Steve
>> > >>
>> > >> On Tue, Feb 28, 2017 at 1:51 PM, Douglas Pauls <
>> > >> [log in to unmask]> wrote:
>> > >>
>> > >>> Argggh Steve, we know ye to be a pirate anyways......
>> > >>>
>> > >>> I had the same question come to mind as Lloyd asked. Pinholes or
>> > >>> dewetting? Pinholes can be due to moisture coming out of the board,
>> > but is
>> > >>> most often point sources of contamination, like droplets of oil or
>> some
>> > >>> other adulterating contaminant in the coating. A picture would
>> help.
>> > >>>
>> > >>>
>> > >>> Doug Pauls
>> > >>> Principal Materials and Process Engineer
>> > >>> Rockwell Collins
>> > >>>
>> > >>> On Tue, Feb 28, 2017 at 2:20 PM, Steve Gregory <[log in to unmask]>
>> > >>> wrote:
>> > >>>
>> > >>>> Hi all,
>> > >>>>
>> > >>>> I'm not trying to hijack this thread, but since we're talking
>> > conformal
>> > >>>> coating here, what could cause an acrylic to appear that there are
>> > tiny
>> > >>>> little fisheyes in the coating, but when you hold the board at an
>> > angle,
>> > >>>> you can clearly see that the area is coated. I know pictures would
>> > help,
>> > >>>> I'll see if I can get some....
>> > >>>>
>> > >>>> Steve
>> > >>>>
>> > >>>> On Tue, Feb 28, 2017 at 12:59 PM, lduso - Diamond-MT.com <
>> > >>>> [log in to unmask]> wrote:
>> > >>>>
>> > >>>> > We do not pre-bake as an internal rule and never a complaint.
>> > Obvious
>> > >>>> > exceptions: We are washing or cleanliness testing the boards.
>> Then
>> > we
>> > >>>> will
>> > >>>> > bake them dry before masking and coating. Or the customer
>> > specifically
>> > >>>> > requires a pre-bake on the drawing. (I always then ask the
>> question;
>> > >>>> "How
>> > >>>> > long after the bake do I have to coat them before they need to be
>> > >>>> baked
>> > >>>> > again?" Strangely, only a few have an answer for that.)
>> > >>>> >
>> > >>>> > I have visited many facilities that conformal coat and I have
>> > >>>> witnessed it
>> > >>>> > both ways but mostly on the "no pre-bake" side. One customer even
>> > >>>> pre-baked
>> > >>>> > their boards before coating with a water based acrylic.
>> > >>>> >
>> > >>>> > Lloyd Duso
>> > >>>> > Plant Manager
>> > >>>> > Diamond-MT
>> > >>>> > (814) 535-3505
>> > >>>> > www.Diamond-mt.com
>> > >>>> >
>> > >>>> > On Tue, Feb 28, 2017 at 2:39 PM, Douglas Pauls <
>> > >>>> > [log in to unmask]> wrote:
>> > >>>> >
>> > >>>> > > Lee,
>> > >>>> > > It Depends.
>> > >>>> > >
>> > >>>> > > We have one facility that has never baked prior to coating
>> > >>>> application.
>> > >>>> > No
>> > >>>> > > evidence of any conformal coating related problems. We have
>> > several
>> > >>>> > > facilities that bake religiously prior to coating application,
>> > also
>> > >>>> for
>> > >>>> > > acrylic. No evidence of any conformal coating related
>> problems.
>> > >>>> > >
>> > >>>> > > I think the biggest factor is how much residual water you
>> have. I
>> > >>>> don't
>> > >>>> > > think your assemblies have to be bone dry before coating. We
>> do a
>> > >>>> lot
>> > >>>> > with
>> > >>>> > > in-line aqueous cleaners, which have heated air knifes that
>> remove
>> > >>>> the
>> > >>>> > bulk
>> > >>>> > > of the water. Now, there might still be some entrapment areas,
>> > but
>> > >>>> if
>> > >>>> > so,
>> > >>>> > > we find them and then blow out those entrapment areas with
>> ionized
>> > >>>> air.
>> > >>>> > >
>> > >>>> > >
>> > >>>> > > Doug Pauls
>> > >>>> > > Principal Materials and Process Engineer
>> > >>>> > > Rockwell Collins
>> > >>>> > >
>> > >>>> > > On Tue, Feb 28, 2017 at 10:20 AM, Lee Hitchens <
>> > >>>> > > [log in to unmask]
>> > >>>> > > > wrote:
>> > >>>> > >
>> > >>>> > > > Hi all
>> > >>>> > > >
>> > >>>> > > > I've recently been asked about baking pcbs before conformal
>> > >>>> coating and
>> > >>>> > > > whether there is any quantified data on the effect on coating
>> > >>>> > > performance.
>> > >>>> > > >
>> > >>>> > > > Does anyone know of any public studies on this or can shed
>> some
>> > >>>> light
>> > >>>> > on
>> > >>>> > > > its effectiveness beyond anecdotal experience ? I would be
>> very
>> > >>>> > grateful
>> > >>>> > > to
>> > >>>> > > > you on this.
>> > >>>> > > >
>> > >>>> > > > Best Regards
>> > >>>> > > >
>> > >>>> > > > Dr Lee Hitchens
>> > >>>> > > >
>> > >>>> > > > SCH Technologies is a Division of SCH Services Limited
>> > >>>> > > >
>> > >>>> > > > www.conformalcoating.co.uk
>> > >>>> > > > Skype: leehitchens
>> > >>>> > > >
>> > >>>> > >
>> > >>>> >
>> > >>>>
>> > >>>> --
>> > >>>>
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>> >
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