I hope you understand that I cannot give too many details about the case, since I don't want our customer to find all his problems being open to the public. Just a few words:
- The pads where ENIG plated.
- Prior to coating the PCBS where not cleaned and boy they where contaminated, I found half of the periodic table on accessible places.
- Coating was applied quite dilettante.
Crazy thing is that this was not a single case. It seems as if a number of people think that conformal coating is an easy going process.
Have a nice day
Günter
>-----Ursprüngliche Nachricht-----
>Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Wenger, George M.
>Gesendet: Freitag, 6. Juli 2012 23:36
>An: [log in to unmask]
>Betreff: Re: [TN] AW: [TN] Copper Dendrites
>
>I my opinion the photographs make it obviously clear that this is
>dendrite growth. The question concerning PCB surface finish really
>doesn't matter. The dendrites are growing from a SMOBC trace. What
>needs to be determined is the contamination necessary for the dendrite
>to grow on the PCB prior to application of solder mask or is the
>contamination coming from the solder assembly process and getting
>through the solder mask to the copper trace.
>
>Regards,
>George
>George M. Wenger
>Senior Principal Reliability / FMA Engineer Andrew Corporation -
>Wireless Network Solutions 40 Technology Drive, Warren, NJ 07059
>(908) 546-4531 Office (732) 309-8964 Mobile
>E-mail: [log in to unmask]
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
>Sent: Friday, July 06, 2012 12:19 PM
>To: [log in to unmask]
>Subject: Re: [TN] AW: [TN] Copper Dendrites
>
>Hi Günter!
>
>Got your pictures posted, they're here:
>
>http://stevezeva.homestead.com/Dendrite_1.jpg
>
>http://stevezeva.homestead.com/Dendrite_2.jpg
>
>Steve
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Grossmann, Guenter
>Sent: Friday, July 06, 2012 12:03 PM
>To: [log in to unmask]
>Subject: [TN] AW: [TN] Copper Dendrites
>
>I sent the to Steve.
>
>Cheers
>
>Günter
>
>
>>-----Ursprüngliche Nachricht-----
>>Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Victor Hernandez
>>Gesendet: Freitag, 6. Juli 2012 17:55
>>An: [log in to unmask]
>>Betreff: Re: [TN] Copper Dendrites
>>
>>What happened to the pictures?
>>
>>Victor,
>>
>>-----Original Message-----
>>From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Reid
>>Sent: Friday, July 06, 2012 10:33 AM
>>To: [log in to unmask]
>>Subject: Re: [TN] Copper Dendrites
>>
>>Ah, Now I understand.
>>
>>Conductive filaments can grow particularly conductive anodic filaments.
>>I was thinking of a dendrite of copper not conductive filaments. I
>>expect dendrites to be larger and of pure copper but you may get
>>dendritic growth with a contaminate, in the presents of water and with
>>an electrical potential.
>>
>>Sorry for my misunderstanding.
>>
>>Sincerely,
>>
>>
>>
>>Paul Reid
>>
>>Program Coordinator
>>
>>PWB Interconnect Solutions Inc.
>>235 Stafford Rd., West, Unit 103
>>Nepean, Ontario Canada, K2H 9C1
>>
>>613 596 4244 ext. 229
>>
>>Skype paul_reid_pwb
>>[log in to unmask]
>>
>>
>>
>>
>>-----Original Message-----
>>From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
>>Sent: July 6, 2012 9:23 AM
>>To: [log in to unmask]
>>Subject: Re: [TN] Copper Dendrites
>>
>>I agree. I have seen dendrites grow under solder mask from on conductor
>>to another, and from a PTH to a conductor, under solder mask.
>>
>>If the residue were benign, until exposed to water, and the coating
>>were to protect it from exposure, it could help.
>>
>>Still, I am skeptical, that it would reduce risk of failure. It would
>>need to be a designed process, not a band aid.
>>
>>It might make things worse.
>>
>>Guy
>>
>>-----Original Message-----
>>From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Naisbitt
>>Sent: Friday, July 06, 2012 8:23 AM
>>To: [log in to unmask]
>>Subject: Re: [TN] Copper Dendrites
>>
>>Hi Neil
>>
>>I stand by my earlier posting on this. Neither a solder resist nor a
>>conformal coating will PREVENT dendrites, they might delay it for a
>>while, but then what is lurking and festering underneath..just when you
>>thought it was safe to go back in the water!?
>>
>>Graham Naisbitt
>>
>>
>>On 5 Jul 2012, at 19:50, Neil Atkinson wrote:
>>
>>> Thanks everyone for comments so far - haven't been on Technet for a
>>while
>>so it was good to get such good responses.
>>>
>>> Really miss Werner for questions like this...
>>>
>>> Actually we have never seen a failure for dendrites; however, we have
>>a
>>customer who has a past problem with another supplier due to dendrites
>>on PCBs and as a result wants us to cover vias with solder resist or
>>conformal coating.
>>>
>>> Tha,
>>>
>>> Neil
>>>
>>> _____________________________________________________________________
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