I respectfully disagree. Any solder joint that fractur
Vadimir,
I respectfully disagree. Any solder joint that fractures at an
interface due to a stress is a brittle solder joint fracture which is a
recognized failure mode or failure "signature". There may be several
mechanisms that cause brittle solder joint fractures but nevertheless
they are fractures at an interface that occur at less then expected
stress rather that cohesive separations in the bulk solder due to an
over-stress. The other names that are typically associated with ENIG
type failures (e.g., "Black Pad", "Black Line Nickel", "Weak Nickel")
are simply names people use to describe what they see or what they think
was the cause. If it was up to me I won't use these names.
Regards,
George
George M. Wenger
Senior Principle FMA / Reliability Engineer
Andrew Corporation Wireless Network Solutions Group
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 (office) (732) 309-8964 (cell)
-----Original Message-----
From: Vladimir Igoshev [mailto:[log in to unmask]]
Sent: Friday, June 29, 2007 1:34 PM
To: TechNet E-Mail Forum; Wenger, George M.
Subject: RE: [TN] - Soldering testing of ENIG Features
George,
Since you spelled out the words "...brittle solder joint fractures on
ENIG..." I want to stress that we should ALWAYS separate Brittle
Fracture of solder joints from Black Pad.
Regards,
Vladimir
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
Sent: Friday, June 29, 2007 1:25 PM
To: [log in to unmask]
Subject: Re: [TN] - Soldering testing of ENIG Features
I'll add my voice with Bev and Dewey. I agree with the a
Steve,
I'll add my voice with Bev and Dewey. I agree with the adjectives they
used "crazy" and "lunacy". However, it does indicate that there are
customers as well as users that don't believe that the ENIG chemistry
providers and board fabricators have eliminated the "Black Pad" type
failures associated with ENIG. I for one commend the ENIG chemistry
providers for doing as good a job as they did to minimize the occurrence
of brittle solder joint fractures on ENIG PCBA's. I don't think I've
gone more than a couple of weeks watching the TN, LF, or other sites
without another case of ENIG failures cropping up. I've know of a
couple of cases of ENIG failures in the past year where the people who
are experiencing ENIG failures refuse to admit they have "Black Pad"
type fractures because they believe that ENIG failures have been fixed.
The main problem I see with brittle solder joint fractures on ENIG
PCBA's is that you can't predict when they are going to happen and you
might not even be able to predict what feature on a board or what board
in a lot on which they will occur. That indicates to me that soldering
wires onto a 624 I/O BGA site is a waste of time. If your PCB
fabricator screwed up and made a really bad lot of boards you want them
to find the bad lot before they send them to you. If you can't convince
your customer not to do the soldering test I would demand that the
customer give you a test specification that calls out exactly what they
want tested. Do they expect you to solder one wire on each of the 624
BGA pads on each of the PCB's your going to assemble? In my mind I
think that is the only way you can have any confidence, but no
guarantee, that you won't have any ENIG brittle solder joint failures.
And to do that would be lunacy. To do anything else however, is a waste
of time.
The alternative that works for us is to use immersion silver and forget
about brittle ENIG solder joint fractures.
Regards,
George
George M. Wenger
Senior Principle FMA / Reliability Engineer
Andrew Corporation Wireless Network Solutions Group
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 (office) (732) 309-8964 (cell)
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Friday, June 29, 2007 12:56 PM
To: [log in to unmask]
Subject: [TN]
Steve,
This is crazy, unless you have developed a bad reputation for producing
Black Pad, which I doubt.
If you want to see one of the Dage testers they are talking about, come
see me.
Why not just take some panels and dissolve off the gold with potassium
thiocyanate and see what the nickel looks like?
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Kelly
Sent: Friday, June 29, 2007 10:42 AM
To: [log in to unmask]
Subject: [TN]
Good Morning to All,
I have a customer who has asked me to do an on-going test for black pad.
The
test would require me to solder wires onto 624 BGA pads and then pull on
the
wires to determine if there is black pad . They have given me no
criteria in
terms of pull strength or what constitutes pass/fail. I obviously need
some
kind of pull tester to do this. Has anyone done anything similar? Any
thoughts or ideas would be appreciated. Regards Steve Kelly
Steve Kelly
(416) 750-8433 (work)
(416) 750-0016 (fax)
(416) 577-8433 (cell)
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