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- > > > > > ---------------------------------------------------------------------------- > > ----- > > 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 > --------------------------------------------------------------------------------- "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 ---------------------------------------------------------------------------------