Electronics Forum | Thu Apr 11 16:37:16 EDT 2002 | pteerink
Profile would be the first place I look. Check your rise and fall rates for temp. Should be no more than 2 deg/sec for rise and 4-6 deg/sec for cooling. Phil
Electronics Forum | Mon Apr 22 18:45:07 EDT 2002 | Steve Townsend
Chances are your profile is fine. There is probably too much paste on the descrete pads. Consider reducing the aperture size of the stencil. Good luck.
Electronics Forum | Tue May 14 20:58:42 EDT 2002 | davef
Maybe the issue is not a proper rework method. Your shorts on the corners are caused by too fast of a profile causing the corners of the BGA to get too hot, too fast, which made them curl, like tatter chips.
Electronics Forum | Thu May 23 12:11:40 EDT 2002 | pjc
One thing I have done in your situation is ask the customer if they have any older design boards that are similar in thermal mass or if they have any from proto work, etc.... Otherwise find/make a board of similar thermal mass as best you can.
Electronics Forum | Fri May 24 11:24:11 EDT 2002 | yngwie
Pete C, Cyber wolf and JohnW...cheers man...excellent input. But I 'm eager to try the method mentioned by Cyber wolf..sounds very convincing. Let see what is the results later. thanx again and have a nice weekend. /yngwie
Electronics Forum | Wed May 29 14:24:51 EDT 2002 | caldon
Stick with round aperatures they work fine. If you are successfully processing fine pitch QFP's then switching to BGA's should be no problem. Profiling is a little tricky, a thermal couple should be mounted at the under/ center of the component. cal
Electronics Forum | Thu Jun 13 09:22:17 EDT 2002 | myfloh
Hi, I would like to have information about means to improve the stability of a SMD-Line: indeed the variation of the daily performance is too important (between 50 and 250 ppm). What is the solution to reduce these variations? climatisation, other re
Electronics Forum | Thu Jun 13 19:58:51 EDT 2002 | john_wsme
Dear All, We have a SRT BGA rework machine and we created several profiles following solder reflow reqirement, but when we installed BGAs, we saw a lot of solder bridging in the conner. Please give us some ideas to eleminate this problem. Thanks in
Electronics Forum | Fri Jun 14 02:13:11 EDT 2002 | john_wsme
Ross, Thanks for your advice. I will take a look at FAB warp and check the pad size. If you also have any suggestions on rework BGA profile, please share some information which is a great help for us. The best regards, John Need help from everybod
Electronics Forum | Fri Jun 14 14:29:22 EDT 2002 | davef
Russ makes good points. Search the archives for: * Links to rework machine profiles. * Discussion on people causing corner shorts on their BGA, when heating them too rapidly, making the corners to curl like potato [potatoe?] chips.
