Electronics Forum | Thu Feb 12 10:19:46 EST 2004 | Bryan
Hi all, These days our customer asks us to figure out ,during reflow,the BGA ball and solder paste,which will first melt? I think it's very hard to get the rusult.coz I think it'll vary at diffrent part of the BGA,and how can this affect the perf
Electronics Forum | Fri Feb 13 11:46:23 EST 2004 | Jack
Is your customer trying to reduce voiding? If the device is using Sn90 / Pb10 and the paste is Sn63/Pb37 the board will melt first. However, if both solders are 183C eutectic, it's a tossup? PCB design, copper weight, bga type (pbga, micro bga, Tbg
Electronics Forum | Tue Feb 17 04:52:13 EST 2004 | John W
There's normally a number of reasons people want to know what melts 1st, 1 - to see if you know, 2 voiding issues - whole can of worms 3 device alignment. One of our collegues has said that most balls are Eutectic, that's in fact not totally correct.
Electronics Forum | Fri Feb 20 13:01:26 EST 2004 | Jay
First, it depends on the alloy composition of the solder. As you might know, eutectic Sn/Pb solder has the lowest melting point among available conventional solder systems. (except those based on Sn-In and Sn-Bi systems.) For example, 63Sn/37Pb - 183
Electronics Forum | Fri May 15 10:04:59 EDT 2009 | aj
Hi all, Is there any standard for percentage voiding on the center thermal pad on a QFN? We use the dot matrix array for paste to allow for outgassing etc, but we have had a couple of xray inspection "fails" for voiding on this pad , in or around 3
Electronics Forum | Mon Jun 01 16:48:16 EDT 2009 | stevezeva
Mika, Have you ever worked with a 3-row I/O QFN? QFN180 to be exact? Steve
Electronics Forum | Mon Dec 16 10:31:21 EST 2002 | davef
Grant, On those 'dry pads', where does the solder paste end-up after soldering? On: * Pads * Component leads * Someplace else [Where?]
Electronics Forum | Mon Dec 16 21:51:28 EST 2002 | grantp
Hi, It's on the pads. They look ok, but when you check the lead comes away from the solder. Regards, Grant Blackmagic Design
Electronics Forum | Wed Jun 27 21:05:48 EDT 2001 | davef
BGA Cycle 1: solder ball attach. BGA Cycle 2: BGA attach to board. BGA Cycle 3: BGA removal from board. BGA Cycle 4: BGA pad dress. BGA Cycle 5: BGA ball replacement. BGA Cycle 6: BGA re-attach to board. Board Cycle 1: BGA attach to board. Boar
Electronics Forum | Tue May 19 15:06:36 EDT 2009 | c111
we had many problems with this. there is no standard that I could ever find. we came up with our own after weeks of headaches. we use 25% as our guide line we use window pain only for the center paid to allow for out gassing and reduce 15-20% globaly
