TECHNET Archives

May 2014

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Vladimir Igoshev <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Vladimir Igoshev <[log in to unmask]>
Date:
Fri, 16 May 2014 13:39:14 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (106 lines)
Thank you Wayne for a "supporting point if view". -:)
Just to add to your possible root causes, I want to say that "exposed Cu" can be seen on ENIG boards if E-Ni doesn't adhere to Cu. We saw it half a year ago and I'm planning to put it ‎on a case histories page of our website.

Regards,

Vladimir Igoshev
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7
Scarborough, ON M1R 5G1
Phone: 647-495-8727
Cell: 416-899-1882
[log in to unmask]
www.sentec.ca
  Original Message  
From: Wayne Thayer
Sent: Friday, May 16, 2014 1:30 PM
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: Re: [TN] pcb issue led to smt components drop from pcb

Hi Carmen-

You must get the surface analyzed. I believe that it "looks like" bare
exposed copper, but the odds are highly against that. As Vladimir has
suggested, you can hire an expert to do the whole analysis. Or you can try
to make this an educational journey for yourself. If you get the surface
analyzed, you'll need an analytical technique capable of identifying the
various species and thicknesses of intermetallics which are on the metal
surfaces.

Also, you need to understand the usage environment. I believe that with the
appropriate amount of temperature cycling, you can get the components to
fall off of anything, provided there is a temperature or temperature
coefficient of expansion difference between the component and substrate.

Looks like I might be the first to set off some tirades by mentioning "black
pad". This is a very ugly intermetallic which is associated with ENIG
surface finish, and we providers of electronic assemblies spend many
sleepless nights about it because you can have a beautiful joint which fails
in even fairly mild usage environments. Obviously we don't have enough
information to suggest this as your problem, but it fits the final result
(as do many other things!).

Shock will take off SMT components also, but that's usually a negligible
probability (exceptions include crystals separating from cell phone
motherboards when the cell phones are dropped or thrown).

Can you provide pictures? We like to see pictures in TechNet. You can't
broadcast them directly, and we were using some kind of sharing site, but
this guy named Steve Gregory takes pride in making it easy to send him
pictures and he'll post them. I think the "cc" address in this email is his
current one, but he's changed companies a few times, so I'm not positive.
He seems to always watch for opportunities to help like this.

Once you post shots, all of the TechNet experts will come out of the
woodwork with additional questions and arguments guaranteed to be somewhat
amusing and possibly very educational.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carmen Aloisi
Sent: Friday, May 16, 2014 11:48 AM
To: [log in to unmask]
Subject: [TN] pcb issue led to smt components drop from pcb

Hello
I'm new to this forum and I'd like to address the following issue to the
group:
after 3 years from delivery of a batct of pcbas we got back from customer
some of them where components are dropping from the pcbas, the solder
remains on the component pin and the pads are with exposed copper.
Could you help me in understanding what was wrong on pcb supplier process or
on ours?

Thanks a lot in advance
Carmen Aloisi
Quality Manager

Eutron S.p.A.
Via Crespi 29 24020 Pradalunga (BG) Italy ph. +39 035697011 fax +39
035697090 m. +39 3355666074 www.eutron.com p.i. 01805190160











.(See attached file: 1.bmp)(See attached file: 5.bmp)(See attached file:
7.bmp)

______________________________________________________________________
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] 
______________________________________________________________________

ATOM RSS1 RSS2