my balls are shining...
Inge
----- Original Message -----
From: "Joyce Koo" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, September 06, 2006 3:01 PM
Subject: Re: [TN] PbCO3
Inge,
could you check if the cbga incoming parts has shining solder surface or
dull looking one...
jk
abcd
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
Sent: Tuesday, September 05, 2006 8:43 AM
To: [log in to unmask]
Subject: Re: [TN] PbCO3
Mornin' Inge!
I have your incredible pictures up! Go to:
http://stevezeva.homestead.com/files/daniel71.jpg
http://stevezeva.homestead.com/files/daniel81.jpg
http://stevezeva.homestead.com/files/daniel91.jpg
I don't know if you've seen this, but there's a presentation that was done
by Dr. Henning Leidecker, Chris Greenwell, and Jay Brusse from NASA on
Tin/Lead whiskers that has some images that are VERY similar to yours. I've
made it a tinyurl below:
http://tinyurl.com/pkm8g
-Steve Gregory-
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar Hernefjord
(KC/EMW)
Sent: Tuesday, September 05, 2006 3:45 AM
To: [log in to unmask]
Subject: Re: [TN] PbCO3
Peer,
You seem to hit the nail. The crystals look exactly as those in Klein's book
page 295. And EDAX shows a lead content approx. 95%, remaining Carbon and
Oxygen. I'll send pics to Steve´s homepage so you all can see that Lead
whiskers exist. Or Lead Growth, as Klein name it. Personally, I prefer
Grouse. The Famous one. Anyway, the "whiskers" we got appear on ALL balls,
and on only CBGAs. Your theory on stress in the solder joint will now be
investigated here. Lead whiskers are not welcome, even if the case is
unique.
Ingemar
Now SAAB Microwave Systems
(Not Ericsson any longer)
-----Original Message-----
From: P. Langeveld [mailto:[log in to unmask]]
Sent: den 4 september 2006 20:50
To: TechNet E-Mail Forum; Ingemar Hernefjord (KC/EMW)
Subject: Re: [TN] PbCO3
That guy is me: Peer Langeveld, Consultant Soft Soldering Processes, living
at 5502 VH 8 The Netherlands, pupil of R.J. Klein Wassink, with
26 years of experience in soft soldering processes whereof 10 years in
lead-free soldering (IDEALS project).
By the way, CBGA's were not known in the early eighties of the last century.
I just mentioned lead whisker growth as an option. A picture is known (Klein
Wassink, page 295) and the needle form is simular to the SEM photo, combined
with the EDAX analysis that only shows lead. And whiskers grow very fast
under stress conditions.
2006/9/4, Ingemar Hernefjord (KC/EMW) <[log in to unmask]>:
> Triple Hmmm!
>
> I used Gilette, which is little rough, but it works fine: dropped a
> board in LN2. When at -196 knocked the backside of the board, and the
> CBGA jumped off. Could then study the cleanliness. No flux residues or
> whatsoever.
> Yepp, Vigon is indeed very active, but why does the phenomenon appear
> only on CBGAs? We have other BGAs on the board, and these have never
> shown such growths.
>
> I'm attempted to go on quite another track for a while. One guy
> proposed whisker growth. And, when you look at the SEM image, you find
> something looking like pressing toothpaste out of its tube: whiskers?
> The guy (who was it?) meant that CBGAs build up mechanical stress
> unlike other components, and hence create whiskers.
>
> Lead whiskers? Quadruple Hmmm. The litterature is very thin about Lead
> whiskers, not to say nearly non-existent. A few cases are reported,
> but not regarding any BGAs, as far as I know. However, I will study
> the few samples I got (am not allowed to touch the sharp boards)and
> see if it can be Lead whiskers, or other type of Lead crystals.
> According to Sod's law, I may be the one to be haunted by Lead whiskers...
>
> Inge
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
> Sent: den 4 september 2006 09:38
> To: [log in to unmask]
> Subject: Re: [TN] PbCO3
>
> Double Hmmmm!
>
> Applying Occam's Razor to this. Put everything you have done to one
> side for a moment and just imagine you were at the early stages of
> investigating this problem.
> You would describe a situation where you are using a reputable resin
> based flux and then clean them in a reputable semi-aqueous cleaner.
> Everywhere is OK, except under a large component.
> My immediate thought would be that you are not cleaning under the
> component as well as you think or at least are not washing/rinsing out
> the cleaner.
> Vigon is a very high pH material and therefore chemically active.
> How do you know you have cleaned under the device? Are you lifting it
> off to do something like ROSE? If there is a flush though problem
> then ROSE will not detect it.
> My apologies for pointing out what is basic stuff like this to someone
> with your knowledge/experience, but sometimes it is easy to overlook
> something when it is too simple.
>
>
> Regards
>
> Mike
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord
> Sent: Sunday, September 03, 2006 10:19 AM
> To: [log in to unmask]
> Subject: Re: [TN] PbCO3
>
> Hmmm....
>
> I have excluded residues that stem from reactions with the solder mask
> and other reactions from solvents and fluxes. The reason is, that such
> residues appear immediately after the soldering process, while our
> residues GROW slowly during weeks and months. And only on CBGAs.
> Furthermore, we have investigated the space between the CBGAs and the
> board, and it's absolutely clean, because we use a very effective and
> powerful Vigon 200 washing machine.
> So, it is still a mystery.
>
> Inge
>
>
>
> ----- Original Message -----
> From: "Mike Fenner" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, August 31, 2006 4:20 PM
> Subject: Re: [TN] PbCO3
>
>
> >I can puzzle out how you could get carbonate but not how you would
> >get lead carbonate. Lead is unreactive compared to other metals
> >present and they would react in favour of the lead, or even if the
> >lead reacted would displace it in the corrosion cell reaction.
> > If you are getting significant carbonate formed so quickly then this
> >would imply a fairly high acidity on the work, which is hard to
> >relate
>
> >to that found in electronic grade fluxes.
> >
> > You have nothing to lose by trying an activated rosin base flux to
> > reduce this stuff -whatever it is - and floating it away as a
> > slag/dross in the rosin, but I doubt it would be effective unless
> > you
> re-melted the solder.
> > If
> > you were to do that it would be similar to some purification
> > processes
>
> > for solders [and other metals,]
> >
> >
> > Regards
> >
> > Mike Fenner
> > Indium Corporation
> >
> > T: + 44 1908 580 400
> > M: + 44 7810 526 317
> > F: + 44 1908 580 411
> > E: [log in to unmask]
> > W: www.indium.com
> > Pb-free: www.Pb-Free.com
> >
> >
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar
> > Hernefjord
> > (KC/EMW)
> > Sent: Thursday, August 31, 2006 9:21 AM
> > To: [log in to unmask]
> > Subject: [TN] PbCO3
> >
> >
> > We got lots of such growth on CBGA balls recently. After
> > soldering/cleaning: nada. After one week in stock: signs of growth.
> > After one month: unacceptable crystals. Now, being insoluble in
> > water and many solvents, some specialists advise you to mix an RA
> > with ethanol, heat this mixture and dip the part until the crystals
vanish.
> > My question to TN is whether there is alternative methods? Some
> > accept
> > PbCO3 growth as being harmless, but this is not our intention,
> > because
>
> > loose particles are semiconducting and can create leakage current
> paths.
> >
> > Brian's book "Cleaning and Contamination of Electronics and
> Assemblies"
> > mention there are five groups of white residues, but, oddly enough,
> > lead carbonate is not included. The chemistry world of soldering
> > residues is so complicated, that I have to ask you for help.
> >
> > Thanks in advance
> > Ingemar Hernefjord
> > Ericsson Microwave Systems
> >
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