all SEM manufacturers have pseudocolouration programs
Inge

----- Original Message -----
From: "Joyce Koo" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 12, 2006 3:24 PM
Subject: Re: [TN] PbCO3 33.5 % NTC


> wow! what is the brand?  how could you get color? excellent...jk
>
> abcd
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
> Sent: Tuesday, September 12, 2006 8:35 AM
> To: [log in to unmask]
> Subject: Re: [TN] PbCO3 33.5 % NTC
>
>
> Morning Inge!
>
> I have your pictures posted. I have never seen such stunning images! You
> have opened my eyes to a strange new world! This looks like some bizzare
> alien landscape. Even if I don't know exactly what they mean, I really
> enjoy looking at them! Here they are for everyone to see:
>
> http://stevezeva.homestead.com/files/daniel121b.jpg
>
> http://stevezeva.homestead.com/files/daniel131b.jpg
>
> http://stevezeva.homestead.com/files/daniel141b.jpg
>
> -Steve Gregory-
>
>
>> About PbCO3,  we used a special tool to take samples from our balls.
> The following SEM/EDAX showed, with 95% confidence, that something
> erects from the > balls: Lead whiskers ! Starts with tiny, less than 0.1
> um wide, whiskers. They seem to grow in all three coordinates, until
> several um wide and many um > long. Close SEM images show how they
> protrude through the ball surface, which is >95% Lead.  Looks like a
> seal's periscope penetrating the polar ice    > with Rock Hudson as
> captain.
>
>> jk proposed, that  the balls may be plated, and that this plating
> creates mechanical tensions, which starts the whisker growth. Anyone
> heard of such    > overplating for BGAs? Wafer bumps, yes, but not heard
> of such treatment for BGAs.
>
>> I'll send scary pics to Stefanos Gregorius.
>
>> Inge
>
>
>
>
>> ----- Original Message -----
>> From: "P. Langeveld" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Monday, September 04, 2006 8:49 PM
>> 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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