TECHNET Archives

September 2006

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"P. Langeveld" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, P. Langeveld
Date:
Mon, 4 Sep 2006 20:49:32 +0200
Content-Type:
text/plain
Parts/Attachments:
text/plain (281 lines)
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
> >
> > ---------------------------------------------------
> > Technet Mail List provided as a service by IPC using LISTSERV 1.8e To
> > unsubscribe, send a message to [log in to unmask] with following text in
>
> > the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt
> > or (re-start) delivery of Technet send e-mail to
> > [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
> > per day of all the posts: send e-mail to
> > [log in to unmask]: SET Technet Digest
> > Search the archives of previous posts at:
> > http://listserv.ipc.org/archives Please visit IPC web site
> > http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> > for additional information, or contact Keach Sasamori at
> > [log in to unmask] or 847-615-7100 ext.2815
> > -----------------------------------------------------
> >
> >
> > ***This email, its content and any files transmitted with it are
> > intended solely for the addressee(s) and may be legally privileged
> > and/or confidential. If you are not the intended recipient please
> > delete and contact the sender by return and delete the material from
> any computer.
> > Any review, retransmission, dissemination or other use of, or taking
> > of any action in reliance upon, this information by persons or
> > entities other than the intended recipient is prohibited.
> >
> > Messages sent via this medium may be subject to delays, non-delivery
> > and unauthorized alteration. This email has been prepared using
> > information believed by the author to be reliable and accurate, but
> > Indium Corporation makes no warranty as to accuracy or completeness.
> > In particular, Indium Corporation does not accept responsibility for
> > changes made to this email after it was sent. Any opinions or
> > recommendations expressed herein are solely those of the author. They
> > may be subject to change without
> > notice.***
> >
> > ---------------------------------------------------
> > Technet Mail List provided as a service by IPC using LISTSERV 1.8e To
> > unsubscribe, send a message to [log in to unmask] with following text in
>
> > the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt
> > or (re-start) delivery of Technet send e-mail to
> > [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
> > per day of all the posts: send e-mail to
> > [log in to unmask]: SET Technet Digest
> > Search the archives of previous posts at:
> > http://listserv.ipc.org/archives Please visit IPC web site
> > http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> > for additional information, or contact Keach Sasamori at
> > [log in to unmask] or 847-615-7100 ext.2815
> > -----------------------------------------------------
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e To
> unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
> (re-start) delivery of Technet send e-mail to
> [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
> per day of all the posts: send e-mail to
> [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at:
> http://listserv.ipc.org/archives Please visit IPC web site
> http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> for additional information, or contact Keach Sasamori at [log in to unmask]
> or 847-615-7100 ext.2815
> -----------------------------------------------------
>
>
> ***This email, its content and any files transmitted with it are
> intended solely for the addressee(s) and may be legally privileged
> and/or confidential. If you are not the intended recipient please delete
> and contact the sender by return and delete the material from any
> computer. Any review, retransmission, dissemination or other use of, or
> taking of any action in reliance upon, this information by persons or
> entities other than the intended recipient is prohibited.
>
> Messages sent via this medium may be subject to delays, non-delivery and
> unauthorized alteration. This email has been prepared using information
> believed by the author to be reliable and accurate, but Indium
> Corporation makes no warranty as to accuracy or completeness. In
> particular, Indium Corporation does not accept responsibility for
> changes made to this email after it was sent. Any opinions or
> recommendations expressed herein are solely those of the author. They
> may be subject to change without notice.***
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e To
> unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
> (re-start) delivery of Technet send e-mail to [log in to unmask]: SET
> Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
> posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
> archives of previous posts at: http://listserv.ipc.org/archives Please
> visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
> additional information, or contact Keach Sasamori at [log in to unmask] or
> 847-615-7100 ext.2815
> -----------------------------------------------------
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
> -----------------------------------------------------
>

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2