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February 2004

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Subject:
From:
Leo Higgins <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 17 Feb 2004 14:12:23 -0800
Content-Type:
text/plain
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text/plain (152 lines)
This sounds like either typical black pad problem, or a passivated Ni
surface under the very thin immersion gold layer.  A determination of the
failure interface as suggested by another respondent is necessary.  A
cross-section of a failed interface and an unseparated interface from the
same sample set would help in making a diagnosis (SEM / EDX map and line
scans for O, Ni, Sn, P).  A scanning Auger map of the surface can help in
seeing if the Au deposit is low density  or porous, and if it has allowed Ni
to oxidize and prevent good wetting after the Au is dissolved in the solder.


Regards,
Leo

------------------------------------
Leo M. Higgins III, Ph.D.
ASAT Inc.
Central Region Mgr. / Director of Sales
[log in to unmask]
3755 Capital of Texas Hwy-So
Suite 100
Austin, TX     USA     78726
tel: 512-383-4593
fax: 512-383-1590
mobile: 512-423-2002
------------------------------------


-----Original Message-----
From: karpinski [mailto:[log in to unmask]]
Sent: Wednesday, February 18, 2004 3:38 PM
To: [log in to unmask]
Subject: Re: [TN] Ni/Au solderability on kapton


Hi Vladimir,

As I know it is Pd.
regards

Vladimir Igoshev schrieb:

>Hi Waclaw,
>
>Do you know what material (Pd or Ru) your board supplier uses to deposit
electroless Ni?
>
>Vladimir Igoshev,
>Research in Motion
>
>Voice: (+1) 519-888-7465, ext. 5283
>Fax: (+1) 519-886-0863
>E-mail: [log in to unmask] <mailto:[log in to unmask]>
>
>
>-----Original Message-----
>From: karpinski [mailto:[log in to unmask]]
>Sent: Wednesday, February 18, 2004 4:15 PM
>To: [log in to unmask]
>Subject: [TN] Ni/Au solderability on kapton
>
>
>Recently we have solderability problems with Ni/Au kapton flex boards
>(0,1 µm Au, 3 µm Ni, 35m Cu).
>We have produced and assembled large number of boards.
>On 10 % of the boards we observe interconnection failures after final
>assembly of the pcbs. If  the suspected solder joints are lightly
>stressed , the connections are easily broken, leaving an open circuits.
> It is  easy to peel  these parts with solder material  from the boards.
>The pads below the removed parts are discolored dark gray and are sleek .
>Some times the handsoldering of the broken joins was successful but
>after small strain the joints  broke again.
>Additional vapor phase soldering  did not improved the the strength of
>the joints.
>This is new problem for us. Does anyone have any experience with this?
>How to rework the boards? How to determine when a board should be
>reworked or
>scrapped? What about reliability issues? Latent failures?
>I would appreciate your help very much
>  regards
>
>--
>Waclaw Karpinski
>I. Physikalisches Institut
>RWTH Aachen
>D - 52074  Aachen
>
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>
>
>

--
Waclaw Karpinski
I. Physikalisches Institut
RWTH Aachen
D - 52074  Aachen
Sommerfeldstr 14, Turm 28
Tel.: +241 802 7181
Fax.: +241 802 2623
Mobil: 0049 173 70 22 548

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847-509-9700 ext.5315
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