As it turns out there was a paper indirectly related to edge coating based around CAF presented at APEX 2002 by Laura Turbini and WR Bent
Bent,W.R., and Turbini,L., Evaluating the Effect of Conformal Coatings in Reducing the rate of conductive of anodic Filament formation APEX 2002 APEX San Diego
I suspect that my customer (military) may have written edge coverage into their spec potentially based on this and similar studies. As an FYI, it is available as a download on the web but I cannot seem to open that PDF file for some reason.
Rich Kraszewski
Plexus
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of lduso - Diamond-MT.com
Sent: Thursday, March 05, 2015 9:44 AM
To: [log in to unmask]
Subject: Re: [TN] R: [TN] Required Conformal Coating of Edges of PCB's
LOL...yep, that's where we went. When I suggested that they just ask their customer to correct the drawing by using IPC parylene spec vice liquid spec the response was "No, we cannot confront them with any changes, just do it as it is called out" Needless to say, after the first couple of batches and one conference call, the drawing was corrected.
Lloyd Duso
Diamond-MT
Plant Manager
(814) 535-3505
www.Diamond-mt.com
On Thu, Mar 5, 2015 at 10:21 AM, Stadem, Richard D. < [log in to unmask]> wrote:
> Uff! I would let them do any rework, if needed. And tell them to have
> fun with that!
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of lduso -
> Diamond-MT.com
> Sent: Thursday, March 05, 2015 8:52 AM
> To: [log in to unmask]
> Subject: Re: [TN] R: [TN] Required Conformal Coating of Edges of PCB's
>
> Lol..You are 100% correct my friend. As most of the strange requests I
> get, they come from the customer's customer. Like when they change
> from a UR coating to parylene but forget to change the thickness
> requirement. Not pretty putting parylene down to 3 mils thick!!
>
> Lloyd Duso
> Diamond-MT
> Plant Manager
> (814) 535-3505
> www.Diamond-mt.com
>
> On Wed, Mar 4, 2015 at 6:42 PM, Steve Gregory <[log in to unmask]> wrote:
>
> > Yep Lloyd, but let me clarify, not my requirement, the customers...
> > [?]
> >
> > Steve
> >
> > On Wed, Mar 4, 2015 at 3:12 PM, lduso - Diamond-MT.com <
> > [log in to unmask]> wrote:
> >
> >> Exactly my point....neither is coating boards to 20 mils thick with
> >> SR conformal coating, but yet we get told to do just that. Isn't
> >> that right Mr.Gregory?...lol
> >>
> >> Lloyd Duso
> >> Diamond-MT
> >> Plant Manager
> >> (814) 535-3505
> >> www.Diamond-mt.com
> >>
> >> On Wed, Mar 4, 2015 at 3:01 PM, SALA GABRIELE <[log in to unmask]>
> wrote:
> >>
> >> > even not in the HDBK-830
> >> >
> >> > Gabriele
> >> >
> >> > -----Messaggio originale-----
> >> > Da: TechNet [mailto:[log in to unmask]] Per conto di Guy Ramsey
> >> > Inviato: mercoledì 4 marzo 2015 20.26
> >> > A: [log in to unmask]
> >> > Oggetto: Re: [TN] Required Conformal Coating of Edges of PCB's
> >> >
> >> > Beware of false knowledge. It is more dangerous than ignorance.
> >> > This is not in the J-STD-001F, or IPC-CC-830B.
> >> >
> >> > Guy
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: TechNet [mailto:[log in to unmask]] On Behalf Of lduso -
> >> Diamond-MT.com
> >> > Sent: Wednesday, March 04, 2015 12:26 PM
> >> > To: [log in to unmask]
> >> > Subject: Re: [TN] Required Conformal Coating of Edges of PCB's
> >> >
> >> > All I can add is this: As coating application contractor we have
> >> > had hundreds of customers over the years and thousands of part
> numbers.
> >> > Everything from NASA Maven to paintball gun CCA's. In all that I
> >> > think I had two part numbers in 8 years that the customer
> >> > required the edge to be coated. One claimed that the reason was
> >> > to seal the edge of the board
> >> and
> >> > the other said it was because there was copper extremely close
> >> > the
> edge.
> >> >
> >> > As everyone has said, it's something worked out between us and
> >> > the customer.
> >> > The funniest part is that they all claim it is in accordance with
> >> > the
> >> IPC.
> >> >
> >> > Lloyd Duso
> >> > Diamond-MT
> >> > Plant Manager
> >> > (814) 535-3505
> >> > www.Diamond-mt.com
> >> >
> >> > On Wed, Mar 4, 2015 at 9:18 AM, Richard Kraszewski <
> >> > [log in to unmask]> wrote:
> >> >
> >> > > Thanks to all for the great insights & discussion on this topic.
> >> > >
> >> > > Rich Kraszewski
> >> > > PLEXUS
> >> > > -----Original Message-----
> >> > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Gregg Owens
> >> > > Sent: Tuesday, March 03, 2015 10:19 AM
> >> > > To: [log in to unmask]
> >> > > Subject: Re: [TN] Required Conformal Coating of Edges of PCB's
> >> > >
> >> > > I vote great minds! :)
> >> > >
> >> > > Gregg
> >> > >
> >> > > -----Original Message-----
> >> > > From: Stadem, Richard D. [mailto:[log in to unmask]]
> >> > > Sent: Tuesday, March 03, 2015 7:36 AM
> >> > > To: TechNet E-Mail Forum; Gregg Owens
> >> > > Subject: RE: [TN] Required Conformal Coating of Edges of PCB's
> >> > >
> >> > > Gregg, I posted almost the same thing and sent it before I saw
> >> > > your posting. Great minds think alike, or something like that,
> >> > > I
> guess!
> >> > > dean
> >> > >
> >> > > -----Original Message-----
> >> > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Gregg Owens
> >> > > Sent: Tuesday, March 03, 2015 9:31 AM
> >> > > To: [log in to unmask]
> >> > > Subject: Re: [TN] Required Conformal Coating of Edges of PCB's
> >> > >
> >> > > Standards do not necessarily define every possible condition,
> >> > > exemplified by this thread's conversations. I am sure the
> >> > > standard committee members for conformal coating need to take
> >> > > note of this condition and come to some conclusion in future
> >> > > editions of the standard. The problem becomes "it depends" is
> >> > > sometimes the right
> >> answer
> >> > for some criteria in IPC standards.
> >> > > That is where the standards state: AABUS (as agreed to between
> >> > > user and supplier (manufacturer)).
> >> > >
> >> > > We live in a complex world where decisions making becomes
> >> > > convoluted between user (customer) and manufacturer. Some users
> >> > > depend on the manufacturer's experience for best industry
> >> > > practices because they may know very little about electronics
> >> > > manufacturing processes let alone end-use implications of those
> >> > > processes (e.g. whether or not to conformally coat a board,
> >> > > what type of coating to use and coverage
> >> > requirements).
> >> > >
> >> > > I live in a bubble where engineering resides with production
> >> > > and communication is very near seamless. So such issues can
> >> > > effectively and efficiently discussed and quickly and
> >> > > effectively decided upon. In the real world of contract
> >> > > manufacturers this
> rarely exists.
> >> > >
> >> > > If life were easy, most of use would not be needed.
> >> > >
> >> > > Gregg
> >> > >
> >> > > -----Original Message-----
> >> > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Dale Ritzen
> >> > > Sent: Tuesday, March 03, 2015 7:07 AM
> >> > > To: [log in to unmask]
> >> > > Subject: Re: [TN] Required Conformal Coating of Edges of PCB's
> >> > >
> >> > > Seriously folks... is this a real or imaginary problem? We have
> >> > > seen both "yes" and "no" opinions over the last several days.
> >> > > Is anyone basing their opinions on a specific standard that
> >> > > states what conditions require the PCB edges to be coated, or
> >> > > is it simply a matter of the customer specifying that
> >> > > requirement on their S.O.W. for the product? Are manufacturers
> >> > > to second guess the customer about the places the product will
> >> > > be used and the environmental conditions it will be placed in
> >> > > that might warrant coating of the PCB edges, or does that
> >> > > really matter anymore with the state of the art PCB
> >> > > manufacturing processes - regardless of the condition of the
> >> > > material left on the edges (with the possible exception of PCBs
> >> > > made of Polyimide
> >> materials)?
> >> > >
> >> > > So far we have seen opinions - not quotes from any standard
> >> > > that covers this. Does that exist, or is it something that the
> >> > > IPC technical committees need to look into for further definition?
> >> > > Sounds to me like it needs some definition in a standard so we
> >> > > all have
> >> > something
> >> > to march to...
> >> > >
> >> > > IMHO,
> >> > > Dale Ritzen, ASQ CQA
> >> > > Quality Manager / ISO Management Representative
> >> > > ___________________________ Austin Manufacturing Services
> >> > > _______________________________________________________________
> >> > > __
> >> > > _____
> >> > > _______________________________________________________________
> >> > > __ ____ This email and any attachments are only for use by the
> >> > > intended
> >> > > recipient(s) and may contain legally privileged, confidential,
> >> > > proprietary or otherwise private information. Any unauthorized
> >> > > use, reproduction, dissemination, distribution or other
> >> > > disclosure of the contents of this e-mail or its attachments is
> >> > > strictly prohibited. If you have received this email in error,
> >> > > please notify the sender immediately and delete the original.
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > -----Original Message-----
> >> > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia
> >> > > Joyce Koo
> >> > > Sent: Monday, March 02, 2015 5:20 PM
> >> > > To: [log in to unmask]
> >> > > Subject: Re: [TN] Required Confromal Coating of Edges of PCB's
> >> > >
> >> > > also there are cut off edges of the PWB like using shear...
> >> > > really bad with all the fiber glass stick out.... there is not
> >> > > enough coating can fix that... (don't laugh, those are real
> surprise you get from far)...
> >> > > jk
> >> > > On Mar 2, 2015, at 10:04 AM, Stadem, Richard D. wrote:
> >> > >
> >> > > > You lost me on that post, Wayne.
> >> > > > Not sure what you are trying to describe when you talk about
> >> > > > drilling thousands of overlapping holes as a method of
> >> > > > routing out a
> >> > PWB?
> >> > > > The edge-coating being discussed was conformal coating, not
> >> > > > plating of the edges?
> >> > > > Sorry if I am slow on the uptick today.
> >> > > > dean
> >> > > >
> >> > > > -----Original Message-----
> >> > > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne
> >> > > > Thayer
> >> > > > Sent: Monday, March 02, 2015 8:44 AM
> >> > > > To: [log in to unmask]
> >> > > > Subject: Re: [TN] Required Confromal Coating of Edges of
> >> > > > PCB's
> >> > > >
> >> > > > I feel the need to point out the obvious:
> >> > > >
> >> > > > -Suppose we singulated a board by using a pcb drill, drilling
> >> > > > thousands of overlapping holes. It's hard to keep drills
> >> > > > sharp, so let's assume we just swap out bits after the same
> >> > > > number of
> "hits"
> >> > > > that we deem the bit good for via hole drilling. Now how
> >> > > > 'bout we coat the exposed edge with plated metal, just to
> >> > > > make sure that if there's a problem with the drilling/routing
> >> > > > process, we have a real good chance of making a short.
> >> > > >
> >> > > > Any reason that should be dis-allowed? Try calculating the
> >> > > > exposed area on the edge vs. all of the via circumferences
> >> > > > you've
> got!
> >> > > >
> >> > > > Therefore, it's ridiculous to specify coating of routed board
> >> > > > edges, which if anything, have less potential to damage fiber
> >> > > > bundles than a drill. Snapped areas are a different category
> >> > > > because drilling/milling has a limited capability to damage
> >> > > > the
> laminate.
> >> > > >
> >> > > > Wayne
> >> > > >
> >> > > > -----Original Message-----
> >> > > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem,
> >> Richard D.
> >> > > > Sent: Monday, March 02, 2015 9:26 AM
> >> > > > To: [log in to unmask]
> >> > > > Subject: Re: [TN] Required Confromal Coating of Edges of
> >> > > > PCB's
> >> > > >
> >> > > > Rich,
> >> > > > In addition to what Dr. Pauls has detailed below, I also want
> >> > > > to point out that whether or not any specification "recommends"
> >> > > > or "does not recommend"
> >> > > > coverage on certain areas of components and PWBs, it is the
> >> > > > assembly drawing which has historically taken precedence over
> >> > > > all standards when it comes to defining conformal coating
> coverage.
> >> > > > This is because every assembly and PWB has different design
> >> > > > requirements and it would be too difficult to document all of
> >> > > > the exceptions to the different rules for each type.
> >> > > > Many circuit boards are simply blanked out on a press,
> >> > > > leaving exposed fiberglass edges, but these are also
> >> > > > typically high-volume, low-reliability PWBs used only for
> >> > > > consumer electronics. All other PWBs are typically routed or
> >> > > > laser cut, and as Doug stated those are typically sealed by
> >> > > > the singulation process. Depending on the type of PWB
> >> > > > material, the method of singulation, and the application,
> >> > > > there may be no need
> to coat the edges.
> >> > > > Or there might be, but then one would expect this to be
> >> > > > detailed as part of the assembly requirements on the drawing.
> >> > > >
> >> > > > dean
> >> > > >
> >> > > > -----Original Message-----
> >> > > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas
> >> > > > Pauls
> >> > > > Sent: Sunday, March 01, 2015 8:07 PM
> >> > > > To: [log in to unmask]
> >> > > > Subject: Re: [TN] Required Confromal Coating of Edges of
> >> > > > PCB's
> >> > > >
> >> > > > Rich,
> >> > > > MIL-I-46058 is simply a materials qualification document. It
> >> > > > does not address the coating of board edges. I would
> >> > > > disagree with Graham and I do not believe that conformal
> >> > > > coating edges of boards is a value added process. Most
> >> > > > boards in high performance electronics have routed edges.
> >> > > > The routing process tends to smear the resin over the glass
> >> > > > reinforcement, sealing the edges. And since most design
> >> > > > standards do not allow internal circuitry closer than 25 mils
> >> > > > from the edge of the boards, water or external contaminants
> >> > > > would have to penetrate
> >> > > > 25 mils of epoxy resin to get to circuitry. If the edges of
> >> > > > the boards were sheared or snapped, where the resin did not
> >> > > > seal the ends, then perhaps the sealing would be justified.
> >> > > > I can say that Rockwell has coated some board edges and left
> >> > > > other
> edges free.
> >> > > > We have no field failure, ever, that can be traced to lack of
> >> > > > coating the board edges.
> >> > > >
> >> > > >
> >> > > > Doug Pauls
> >> > > > Principal Materials and Process Engineer Rockwell Collins
> >> > > >
> >> > > > On Fri, Feb 27, 2015 at 10:51 AM, Richard Kraszewski <
> >> > > > [log in to unmask]> wrote:
> >> > > >
> >> > > >> Does anyone recall which MIL document calls out the
> >> > > >> requirement to cover the PCB edges of assemblies?
> >> > > >> I have been led to believe that one exists but that more
> >> > > >> than likely it is not MIL-I-46058C.
> >> > > >>
> >> > > >> Any thoughts??
> >> > > >>
> >> > > >> Rich Kraszewski
> >> > > >> Plexus
> >> > > >>
> >> > > >> ____________________________________________________________
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