Electronics Forum | Sat Oct 06 05:33:47 EDT 2001 | spchua
I had recently encounter the "black and grey" pads problems for the BGA pad after the convection re-flow. The pads shows in in "black and grey" color and a litter solder in it, and it happen in ramdom, when applied heat and solder on the "black and g
Electronics Forum | Sat Oct 06 08:42:21 EDT 2001 | davef
Please give us additional background on your board, solder, process, etc. If you are talking about black pad in ENIG solderability preservative, check the fine SMTnet archives to get started.
Electronics Forum | Wed Feb 18 12:42:43 EST 2004 | babe
OK, if the sphere of the ball and the paste on the pad are both eutectic, 63/37 then the paste will reflow first causing a drop of the component, after which the spheres will reflow causing a double drop and a good intermettalic. You can see this by
Electronics Forum | Thu Feb 12 11:35:17 EST 2004 | Kris
what is the composition of the paste and ball ? Interesting to know why the customer is asking you to look for it Thx
Electronics Forum | Fri Feb 13 11:19:07 EST 2004 | Evtimov
Hi Bryan The answer is in the paste compozition. Balls of the BGA are usually made by eutetic solder paste.
Electronics Forum | Fri Feb 20 15:07:31 EST 2004 | agp
I agree with Jay. The paste will reflow first before the balls. The main reason is the flux content and the dimension of the spheres.
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 | Fri Feb 27 11:33:32 EST 2004 | Bryan
Very strange question,but interesting.Is there anyone who have conducted any experiments to figure out the results?I made a profile board,one thermal couple on pad and other one drilled into the ball of BGA.the 2 points are perpendicular to conveyor
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.
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