In electroless Ni/Au it is often difficult to control Phosphorus content in
the deposit.
The various chemistries give different responses to soldering - on surface /
in the hole / and also for wire bonding.
May be a heart to heart talk with the fab shop and establishing acceptable
limits is best soln.
Anil
----- Original Message -----
From: Pat Brooks <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, September 17, 1999 2:41 AM
Subject: Re: [TN] Subj: Poor Wetting/Solderability/Contamination/????
> Ron
>
> Is the surface electroless Ni and immersion Au?
>
> -----Original Message-----
> From: Hollandsworth, Ron [mailto:[log in to unmask]]
> Sent: Thursday, September 16, 1999 3:12 PM
> To: [log in to unmask]
> Subject: [TN] Subj: Poor Wetting/Solderability/Contamination/????
> Importance: Low
>
>
> Good Day TechNet:
> I am experiencing poor wetting, insufficient hole fill, and what appears
to
> be phosphorus contamination. Some details are:
>
> 1. Happening/Noticiable after wavesolder operation.
> 2. Wavesolder setup is: 230 F top side board temperature, Low Residue
VOC
> Free Water Based Flux by Kester, minimal to no solder balls (appears
> flux/preheat has sufficient timing), conveyor speed at 3 ft. per minute,
and
> spray fluxer with pitch/pressure/speed control (good coverage).
> 3. Handsoldering seems to work, however, may have selected boards that
are
> solderable.
> 4. Connector leads are within tolerance and board is within tolerance,
> however, at max and min tolerance the lead protrusion left is minimal.
> Believe it acts like a plug, however, defect characteristics appear on
> bottom side of board.
> 5. Nickel/Gold board - electroless plating
> 6. Relatively fine pitch connectors, however, larger .050 mil connector
has
> shown poor wetting, insufficient, cantamination, etc., as well as randomly
> other parts of board.
> 7. Boards are not stored for a long time before use. Cycle time very
short
> from dock to line.
>
> I noticed that last week someone else had a problem that is about the same
> as this. We have also tried paste-in-hole for the connectors and it
appears
> to help significantly, but there is still a problem, still you should be
> able to wavesolder these boards and not add an extra step in the process.
>
> Good topic, I think. Has any one solved this issue or speculation on how
to
> solve it. I read the speculations, but it appears to be plaguing other
> besides just us at the present time. Plus it comes and goes.
>
> Looking for clues?????
>
> Ron Hollandsworth
> Ops Task Leader
> ITT
> [log in to unmask]
>
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