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:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Tue, 12 Sep 2006 08:33:37 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (283 lines)
Thanks, Reuven
This brings me to the question of PbCO3 lead whiskers. They must be
caused by internal stressors. If seen around the widest diameter of the
lead balls like in Inge's case where no electro-chemical reaction would
be the cause if the balls were actually a Pb90/Sn10 alloy, the whiskers
are likely caused by the lateral stresses from the CTE mismatch between
the aluminum oxide CBGA substrate and the PWB substrate the components
are soldered to.  These stresses would thus be concentrated near the
widest part of the ball. If the balls are lead plating over some other
metal, the lead whiskers would be from stresses due to the plating, and
would not be focused on the equator, but distributed evenly over the
ball.

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Tuesday, September 12, 2006 8:17 AM
To: Stadem, Richard D.
Subject: RE: [TN] PbCO3

I don't think so, dendrites caused by electro - chemical  reaction and
whiskers caused by internal stress and because of metallurgical
structure.


Best  Regards

Reuven  ROKAH


e mail: [log in to unmask]


 

             "Stadem, Richard

             D."

             <Richard.Stadem@g
To 
             d-ais.com>                <[log in to unmask]>

 
cc 
             12/09/2006 16:07

 
Subject 
                                       RE: [TN] PbCO3

 

 

 

 

 

 





So is there a relationship between the microcrystalline dendritic growth
(size and shape) in metals and whisker formation?

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Tuesday, September 12, 2006 8:02 AM
To: TechNet E-Mail Forum; Stadem, Richard D.
Subject: Re: [TN] PbCO3

Hi Stadem,

According my best knowledge,

Dendrites phenomenon, look like  roots and they are on the surface,

Whiskers phenomenon, look like a needle and grow from the surface /
solder joint  in different angels.


Best  Regards

Reuven  ROKAH





             "Stadem, Richard

             D."

             <Richard.Stadem@G
To
             D-AIS.COM>                [log in to unmask]

             Sent by: TechNet
cc
             <[log in to unmask]>


Subject
                                       Re: [TN] PbCO3

             12/09/2006 15:44





             Please respond to

              TechNet E-Mail

                   Forum

             <[log in to unmask]>

             ; Please respond

                    to

             "Stadem, Richard

                    D."

             <Richard.Stadem@G

                D-AIS.COM>









Reuven,
Can you tell us the difference between dendrites and whiskers?

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven ROKAH
Sent: Tuesday, September 12, 2006 7:04 AM
To: [log in to unmask]
Subject: Re: [TN] PbCO3

Hi Ingemar,

1.    Are you sure its Lead (Pb) Wishers? pls inform how?

2.    Dendrites is another phenomenon than whiskers.

3.    Can you repeat with this kind of failure? ("whiskers?").


Best  Regards

Reuven  ROKAH

e mail: [log in to unmask]



             "Ingemar
             Hernefjord
             (KC/EMW)"
To
             <ingemar.hernefjo         [log in to unmask]
             [log in to unmask]>
cc
             Sent by: TechNet
             <[log in to unmask]>
Subject
                                       Re: [TN] PbCO3

             12/09/2006 12:56


             Please respond to
              TechNet E-Mail
                   Forum
             <[log in to unmask]>
             ; Please respond
                    to
                 "Ingemar
                Hernefjord
                 (KC/EMW)"
             <ingemar.hernefjo
             [log in to unmask]>







Klein Wassink mentiones a little about Tin Whiskers (dendrites).
One guy here at our company has written a paper about Tin whiskers.
NASA have a lot about Tin whiskers. Et cetera.
But few have anything about Lead whiskers.
Only thread I have is one picture from Klein Wassink. That picture is
like a copy of our own photos.

Question is if anyone of you have any idea about the following:

A. Can Lead whiskers grow through Humiseal acrylic? I've heard that Tin
whiskers can.
B. Can alcalic saponifier cleaning of BGA high lead balls start whisker
formation?
C. Do Lead whiskers burn off easily like Tin whiskers, or are they
"stronger" ?
D. What can the reason be that the Lead whiskers grow only around the
ball's "equator" ?
E. The CBGA platform is said to come from IBM. Do they differ from
others on ball making?

These questions may not be suitable for this forum, but I make a try,
well knowing that many of you are extremly experienced.

Thx in advance

Ingemar Hernefjord
Now SAAB 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
-----------------------------------------------------

---------------------------------------------------
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