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March 2001

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From:
"Marsico, James" <[log in to unmask]>
Date:
Fri, 2 Mar 2001 13:05:54 -0500
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1.0
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Gabriela Bogdan <[log in to unmask]>
Reply-To:
"TechNet E-Mail Forum." <[log in to unmask]>, "Marsico, James" <[log in to unmask]>
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We routinely re-ball ceramic BGAs without incidence.

Jim Marsico
Senior Engineer
Production Engineering
AIL/Electronics Systems Group
An EDO Company
[log in to unmask] <mailto:[log in to unmask]>

        -----Original Message-----
        From:   Gabriela Bogdan [SMTP:[log in to unmask]]
        Sent:   Friday, March 02, 2001 1:12 PM
        To:     [log in to unmask]
        Subject:        Re: [TN] Reballing concern

        Daan,
        Are ceramic BGA's OK for reballing?
        Gaby

        "d. terstegge" wrote:

        > Hi Brad,
        >
        > I share your concern, and for that reason we do reballing only on
prototypes, where the customer is interested in one thing only: getting a
working board, as soon as possible.
        > Some time ago I did an experiment where I reballed and reworked a
BGA five times. It still worked !  (but the real question remains: how long
will it keep functioning ?).
        >
        > Kind regards,
        >
        > Daan Terstegge
        > Unclassified mail
        > Personal Website: http://www.smtinfo.net
        >
        > >>> Brad Kendall <[log in to unmask]> 03/02 3:05 pm >>>
        > I see that Steve is having parts reballed.  I never
        > reballed BGA parts, but have heard of a lot of people
        > doing it lately.  I have concerns with reballing and
        > would like to see if you guys agree.  Now, it is
        > critical that most BGA parts are NOT exposed to air
        > prior to reflow.  I have seen some that have been and
        > they popcorn.  So we always kept them sealed or in a
        > nitrogen cabinet.  So, now you have run a part,
        > determined there is an open or short, but that the
        > chip itself is good.  The board may have been built a
        > week ago, may be sent out of house for rework, thus
        > exposed to climate changes.  Then heat is put on it in
        > rework.  This part probably has moisture in it and may
        > popcorn.  Then you reball and put heat on it again!
        > Is the part any good?  It has seen a minimum of 3 heat
        > cycles, if it saw heat for backside glue cure or
        > double reflow or wave, then it has seen even more.
        >
        > I understand reballing is done to save expensive
        > parts, but the risk of destroying the part during
        > rework is a major concern.
        >
        > Brad Kendall
        > --- Bob Perkins <[log in to unmask]> wrote:
        > > Hi Steve
        > >
        > > One thing I have noticed is that if you do not have
        > > your voiding under
        > > control you can create bridging.  I have seen a
        > > voids large enough to
        > > expanded the ball enough to invade in the space of
        > > the next ball, and if
        > > that ball has a large void also a bridge can occur.
        > > If this is an known
        > > issue then a new paste may be in order.
        > >
        > > I see two issues with your profile that could
        > > possibly be causing a
        > > problem, I don't think all the balls on the BGA are
        > > reflowing at the same
        > > time.  I think you can improve this by setting up
        > > your reflow closer to 183
        > > before spike. There could also be a hot slump issue
        > > also at the beginning or
        > > reflow, I would recommend you try this to get a more
        > > simultaneous reflow.
        > >
        > > 130 160 180 183 240
        > > 130 160 180 183 240
        > >
        > >
        > > How you guys doing in Seattle after that shake up?
        > > We felt it up here in Vancouver.
        > >
        > > Bob Perkins
        > > SMT Manufacturing Process /
        > > Automation Technician
        > > Aitmronics-Delta
        > >
        > >
        > >
        > >
        > > -----Original Message-----
        > > From: Stephen R. Gregory [mailto:[log in to unmask]]
        > > Sent: Tuesday, February 27, 2001 1:34 PM
        > > To: [log in to unmask]
        > > Subject: [TN] Heat-sinked BGA Bridging...
        > >
        > >
        > > Hi all!
        > >
        > > This topic is a "moldy-oldie", but I've started to
        > > experience bridges again
        > > with this TI DSP (TMS320C6201GJC200). I've been
        > > doing okay up unil recently.
        > > We build these boards in work orders of around 25
        > > pieces.
        > >
        > > Our last run we had 7 boards bridged out of 25!!
        > > Sent the boards out to be
        > > reworked. I asked that they be x-rayed before and
        > > after, and to my surprise
        > > after looking at the x-ray images, they were all
        > > bridging in the same
        > > general
        > > area.
        > >
        > > It's a 4-row periphery BGA, and the bridges are
        > > occuring on the inner two
        > > rows, around the center of the part, at the same
        > > side of the part.
        > >
        > > What's funny, is that the vendor we use to rework
        > > the boards for us is
        > > having
        > > difficulty as well. We've been asking him to remove,
        > > re-ball, and re-install
        > > the part, they said they've been having about a 50%
        > > success rate doing
        > > this...they've been getting the bridges too. They
        > > have a nice full-blown SRT
        > > BGA rework station and do this for a living.
        > >
        > > I print 6-mils of paste (square apertures for the
        > > BGA), have a Conceptronic
        > > HVN-70 which I run:
        > >
        > > 150     160     170     180     240
        > > 150     160     170     180     240
        > >
        > > 25-in. per min
        > >
        > > We never have had these problems before...it all
        > > started when TI put the
        > > heatsink into the top of the part. I've looked at
        > > our paste print and it's
        > > dead on, placement is dead on too, we verify that
        > > with a Ersascope.
        > >
        > > My question is could there be something wrong with
        > > the part? Warping causes
        > > bridges at the corners, right? Why would it bridge
        > > in the interior rows at
        > > the same general area?
        > >
        > > Thanks in advance!
        > >
        > > -Steve Gregory-
        > >
        > >
        >
----------------------------------------------------------------------------
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        > > (http://www.ipc.org/html/forum.htm) for additional
        > > information, or contact Keach Sasamori at
        > > [log in to unmask] or 847-509-9700
        > > ext.5315
        > >
        >
----------------------------------------------------------------------------
        > > -----
        > >
        > >
        >
----------------------------------------------------------------------------
-----
        > > Technet Mail List provided as a free service by IPC
        > > using LISTSERV 1.8d
        > > 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 delivery of Technet send the
        > > following message: SET Technet NOMAIL
        > > Search previous postings at: www.ipc.org > On-Line
        > > Resources & Databases > E-mail Archives
        > > Please visit IPC web site
        > > (http://www.ipc.org/html/forum.htm) for additional
        > > information, or contact Keach Sasamori at
        > > [log in to unmask] or 847-509-9700 ext.5315
        > >
        >
----------------------------------------------------------------------------
-----
        >
        > __________________________________________________
        > Do You Yahoo!?
        > Get email at your own domain with Yahoo! Mail.
        > http://personal.mail.yahoo.com/
        >
        >
----------------------------------------------------------------------------
-----
        > Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
        > 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 delivery of Technet send the following
message: SET Technet NOMAIL
        > Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
        > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
        > information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
        >
----------------------------------------------------------------------------
-----
        >
        >
----------------------------------------------------------------------------
-----
        > Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
        > 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 delivery of Technet send the following
message: SET Technet NOMAIL
        > Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
        > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
        > information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
        >
----------------------------------------------------------------------------
-----

        "d. terstegge" wrote:

        > Hi Brad,
        >
        > I share your concern, and for that reason we do reballing only on
prototypes, where the customer is interested in one thing only: getting a
working board, as soon as possible.
        > Some time ago I did an experiment where I reballed and reworked a
BGA five times. It still worked !  (but the real question remains: how long
will it keep functioning ?).
        >
        > Kind regards,
        >
        > Daan Terstegge
        > Unclassified mail
        > Personal Website: http://www.smtinfo.net
        >
        > >>> Brad Kendall <[log in to unmask]> 03/02 3:05 pm >>>
        > I see that Steve is having parts reballed.  I never
        > reballed BGA parts, but have heard of a lot of people
        > doing it lately.  I have concerns with reballing and
        > would like to see if you guys agree.  Now, it is
        > critical that most BGA parts are NOT exposed to air
        > prior to reflow.  I have seen some that have been and
        > they popcorn.  So we always kept them sealed or in a
        > nitrogen cabinet.  So, now you have run a part,
        > determined there is an open or short, but that the
        > chip itself is good.  The board may have been built a
        > week ago, may be sent out of house for rework, thus
        > exposed to climate changes.  Then heat is put on it in
        > rework.  This part probably has moisture in it and may
        > popcorn.  Then you reball and put heat on it again!
        > Is the part any good?  It has seen a minimum of 3 heat
        > cycles, if it saw heat for backside glue cure or
        > double reflow or wave, then it has seen even more.
        >
        > I understand reballing is done to save expensive
        > parts, but the risk of destroying the part during
        > rework is a major concern.
        >
        > Brad Kendall
        > --- Bob Perkins <[log in to unmask]> wrote:
        > > Hi Steve
        > >
        > > One thing I have noticed is that if you do not have
        > > your voiding under
        > > control you can create bridging.  I have seen a
        > > voids large enough to
        > > expanded the ball enough to invade in the space of
        > > the next ball, and if
        > > that ball has a large void also a bridge can occur.
        > > If this is an known
        > > issue then a new paste may be in order.
        > >
        > > I see two issues with your profile that could
        > > possibly be causing a
        > > problem, I don't think all the balls on the BGA are
        > > reflowing at the same
        > > time.  I think you can improve this by setting up
        > > your reflow closer to 183
        > > before spike. There could also be a hot slump issue
        > > also at the beginning or
        > > reflow, I would recommend you try this to get a more
        > > simultaneous reflow.
        > >
        > > 130 160 180 183 240
        > > 130 160 180 183 240
        > >
        > >
        > > How you guys doing in Seattle after that shake up?
        > > We felt it up here in Vancouver.
        > >
        > > Bob Perkins
        > > SMT Manufacturing Process /
        > > Automation Technician
        > > Aitmronics-Delta
        > >
        > >
        > >
        > >
        > > -----Original Message-----
        > > From: Stephen R. Gregory [mailto:[log in to unmask]]
        > > Sent: Tuesday, February 27, 2001 1:34 PM
        > > To: [log in to unmask]
        > > Subject: [TN] Heat-sinked BGA Bridging...
        > >
        > >
        > > Hi all!
        > >
        > > This topic is a "moldy-oldie", but I've started to
        > > experience bridges again
        > > with this TI DSP (TMS320C6201GJC200). I've been
        > > doing okay up unil recently.
        > > We build these boards in work orders of around 25
        > > pieces.
        > >
        > > Our last run we had 7 boards bridged out of 25!!
        > > Sent the boards out to be
        > > reworked. I asked that they be x-rayed before and
        > > after, and to my surprise
        > > after looking at the x-ray images, they were all
        > > bridging in the same
        > > general
        > > area.
        > >
        > > It's a 4-row periphery BGA, and the bridges are
        > > occuring on the inner two
        > > rows, around the center of the part, at the same
        > > side of the part.
        > >
        > > What's funny, is that the vendor we use to rework
        > > the boards for us is
        > > having
        > > difficulty as well. We've been asking him to remove,
        > > re-ball, and re-install
        > > the part, they said they've been having about a 50%
        > > success rate doing
        > > this...they've been getting the bridges too. They
        > > have a nice full-blown SRT
        > > BGA rework station and do this for a living.
        > >
        > > I print 6-mils of paste (square apertures for the
        > > BGA), have a Conceptronic
        > > HVN-70 which I run:
        > >
        > > 150     160     170     180     240
        > > 150     160     170     180     240
        > >
        > > 25-in. per min
        > >
        > > We never have had these problems before...it all
        > > started when TI put the
        > > heatsink into the top of the part. I've looked at
        > > our paste print and it's
        > > dead on, placement is dead on too, we verify that
        > > with a Ersascope.
        > >
        > > My question is could there be something wrong with
        > > the part? Warping causes
        > > bridges at the corners, right? Why would it bridge
        > > in the interior rows at
        > > the same general area?
        > >
        > > Thanks in advance!
        > >
        > > -Steve Gregory-
        > >
        > >
        >
----------------------------------------------------------------------------
        > > -----
        > > Technet Mail List provided as a free service by IPC
        > > using LISTSERV 1.8d
        > > 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 delivery of Technet send the
        > > following message: SET
        > > Technet NOMAIL
        > > Search previous postings at: www.ipc.org > On-Line
        > > Resources & Databases >
        > > E-mail Archives
        > > Please visit IPC web site
        > > (http://www.ipc.org/html/forum.htm) for additional
        > > information, or contact Keach Sasamori at
        > > [log in to unmask] or 847-509-9700
        > > ext.5315
        > >
        >
----------------------------------------------------------------------------
        > > -----
        > >
        > >
        >
----------------------------------------------------------------------------
-----
        > > Technet Mail List provided as a free service by IPC
        > > using LISTSERV 1.8d
        > > 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 delivery of Technet send the
        > > following message: SET Technet NOMAIL
        > > Search previous postings at: www.ipc.org > On-Line
        > > Resources & Databases > E-mail Archives
        > > Please visit IPC web site
        > > (http://www.ipc.org/html/forum.htm) for additional
        > > information, or contact Keach Sasamori at
        > > [log in to unmask] or 847-509-9700 ext.5315
        > >
        >
----------------------------------------------------------------------------
-----
        >
        > __________________________________________________
        > Do You Yahoo!?
        > Get email at your own domain with Yahoo! Mail.
        > http://personal.mail.yahoo.com/
        >
        >
----------------------------------------------------------------------------
-----
        > Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
        > 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 delivery of Technet send the following
message: SET Technet NOMAIL
        > Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
        > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
        > information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
        >
----------------------------------------------------------------------------
-----
        >
        >
----------------------------------------------------------------------------
-----
        > Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
        > 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 delivery of Technet send the following
message: SET Technet NOMAIL
        > Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
        > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
        > information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
        >
----------------------------------------------------------------------------
-----


----------------------------------------------------------------------------
-----
        Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
        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 delivery of Technet send the following message:
SET Technet NOMAIL
        Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
        Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
        information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315

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

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

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