Ingemar,
It seems our emails will have crossed. I will send you mine if you will send
me yours - photo's that is!
Regards,
Graham Naisbitt
[log in to unmask]
WEB: http://www.concoat.co.uk
CONCOAT Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK
Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
----- Original Message -----
From: <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 25, 1999 2:40 PM
Subject: Re: [TN] BGA solder residues
Will try that reflowing, Roger, good idea,
will also try XPS for chemical determination. Roger, I tried to cook the
cabbage in the following solution: 1part HNO3, 4parts glacial acetic acid,
10
parts H2O. The result was surprising. One dip 2 seconds in the solution
(room
temperature) and then rinsing in tap water and all crystals were gone! If we
are desperados, do you think we dare to perform handcleaning the boards that
way in order to avoid production stop? (The man with the saucers may have
something to say, we are also making airborne electronics. Any bad feelings
about the idea? Will the MIL people scream?)
This did not tell why the crystals grow, that's still the headache, maybe
your
proposals will give something.
If you want a photo of the cabbage, I can mail such a one to you, Roger. Or
anyone else who is interested.
See you /
Ingemar
> Ingemar,
>
> Have you tried "reflowing" the individual parts and seeing if they
> bloom on their own? If your lucky, it could be due to a suspect
single
> component type if unlucky its a compound reaction from interactions.
> (could be some gunk leaching out of ceramic etc Dont know about
PbCO3
> but try something like an XPS analysis, which should more or less
tell
> you how the stuff is bonded together and in what relative
> concentrations.
>
> Roger
> Motorola AIEG
>
>
> ______________________________ Reply Separator
_________________________________
>
> Subject: [TN] BGA solder residues
> Author: "TechNet E-Mail Forum." <[log in to unmask]> at #email
> Date: 25/08/99 12:29
>
>
> Oumphf!
> You can't pronounce that? Like me not being able to see what strange
> roses we find between the balls after BGA on FR4 after 10 minutes in a
> REHM heat conveyour oven. Top temp is +230 / 1 minute. Preheat is
> included in the 10 minutes. Kester 229D is used (if a Kester man reads
> this, please give a line or two in response. The residues grow to
> something that reminds of roses or cabbage! Colour in daylight is white,
> but the residues do not seem to belong to the ordinary white residues
> (Tin Abiate, polymerized rosin and lead salts). Flakes are <<1micron
> thick and up to 50microns in diameter. EDAX gives 99%Lead and bal is some
> Tin and Carbon and other random elements. Not soluble in the usual
> solvents like Ethylene, Perclorethylene, Acetone etc. And that is
> natural, as the residues are inorganic. Kester 229D is not QPL'd. Paste
> Sn62Pb36Ag2 is screenprinted on traditional Cu/Ni/Sn-pads. We have used
> this Kester formula for years for other products without seeing cabbage
> nor roses. BGA is ceramic C4 from Mota, number of balls (bumps) approx.
> 25x25 matrix.
>
> Can it be PbCO3? The flux is RMA and contains clorides.
>
> The line is stopped, nothing will be delivered until the cabbage growth
> is eliminated. Special question to SIRguru labs: can we send this job to
> you if our qualification does not cover the need?
>
> Regards
> Ingemar Hernefjord
> Ericsson Microwave Systems
>
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