some of the design required wrap ground or signal via edge.... after
singulation, you do need cover up... (I am not say using conformal
coat...it is not consider a dielectric according to my book ;-).
jk
On Mar 4, 2015, at 3:07 PM, Stadem, Richard D. wrote:
> And the IPC Design Guidelines always call out a recommended .050"
> setback of all copper features from the edges of the boards as well
> as from the non-plated drilled holes (tooling holes, etc.). That is
> a safety buffer for misregistered layers, so they do not short out
> at the edges of the boards or to mounting hardware, etc. No water
> vapor will penetrate .050" (or even .025") into the PWB
> significantly enough to cause performance issues.
> If you have a PWB vendor who cannot maintain .050" +-.003" from
> exposed edges, time for a new PWB vendor.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of SALA GABRIELE
> Sent: Wednesday, March 04, 2015 2:01 PM
> To: [log in to unmask]
> Subject: [TN] R: [TN] Required Conformal Coating of Edges of PCB's
>
> 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
>>>>
>>>> ___________________________________________________________________
>>>> __
>>>> _
>>>> This email has been scanned by the Symantec Email Security.cloud
>>>> service.
>>>> For more information please contact helpdesk at x2960 or
>>>> [log in to unmask]
>>>> ___________________________________________________________________
>>>> __
>>>> _
>>>>
>>>
>>>
>>> ____________________________________________________________________
>>> __ This email has been scanned by the Symantec Email Security.cloud
>>> service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask]
>>> ____________________________________________________________________
>>> __
>>>
>>> ____________________________________________________________________
>>> __ This email has been scanned by the Symantec Email Security.cloud
>>> service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask]
>>> ____________________________________________________________________
>>> __
>>>
>>> ____________________________________________________________________
>>> __ This email has been scanned by the Symantec Email Security.cloud
>>> service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask]
>>> ____________________________________________________________________
>>> __
>>
>>
>> _____________________________________________________________________
>> _
>> This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>> _____________________________________________________________________
>> _
>> This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>> _____________________________________________________________________
>> _
>> This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>> _____________________________________________________________________
>> _
>> This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>> _____________________________________________________________________
>> _
>> This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud
> service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud
> service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
>
>
> ---
> Questa e-mail è priva di virus e malware perché è attiva la
> protezione avast! Antivirus.
> http://www.avast.com
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud
> service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud
> service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|