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June 2007

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Subject:
From:
"Wenger, George M." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M.
Date:
Fri, 29 Jun 2007 14:19:06 -0400
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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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