Electronics Forum | Mon Sep 24 11:12:56 EDT 2001 | nwyatt
Hi. We are currently using an unconventional method to rework a micro BGA - removing component with hot air, fluxing the area, placing the part with pick and place, then reflowing it in the oven. The reason we are doing it this way and not with a r
Electronics Forum | Fri Jan 13 13:43:51 EST 2006 | russ
As far as I have determined, the Gel and Tacky are the same animal. Just flux works well, I did forget to mention that this flux only method will not work with a CCGA (Ceramic Column Grid Array) since these columns are not meant to be reflowed.
Electronics Forum | Fri Sep 28 16:51:41 EDT 2001 | pcmarch
I have had success by applying the paste flux with my finger, using a finger cot and spreading it on the PCB. This seems to put it on more consistently than using a brush.
Electronics Forum | Mon Jan 16 09:15:40 EST 2006 | russ
I can't see why it would be any different, You are melting the balls into reflow to the pad. In my opinion, paste is only useful in this situation to keep the part on the board during placement along with some planarity concerns in some instances.
Electronics Forum | Sat Jan 14 06:38:04 EST 2006 | DannyJ
Hi Ken, Good question, and I did search for what you are asking, but unable to find anything conclusive about using tacky flux vs. solder. In reliability, it depends on which section of the process you are talking about. Mainly (and there are sev
Electronics Forum | Tue Sep 25 15:48:34 EDT 2001 | mparker
Scavenge all the old solder off the board and the chip. Micro screen paste to the chip. As far as thickness, check your aspect ratio to determine the spec. Eliminate just one variable at a time to get to the root cause. Start by not using the tacky
Electronics Forum | Mon Oct 01 04:01:08 EDT 2001 | wbu
You got the right feeling for that I guess but what if somebody else is doing your trick, is it still repeatable? Personally I wouldn�t trust that method more than the brushing. Did you try the dipping method ? The thing from Dave with this "card-com
Electronics Forum | Tue Sep 25 13:01:48 EDT 2001 | Hussman
If the flux you are applying by brush is alcohol based, use some alcohol on a few failed PCBs and retest. It souldn't take a lot of flux to reflow the balls to a pad that's already covered with solder and flux from the first BGA - unless you are cle
Electronics Forum | Thu Jan 19 06:25:42 EST 2006 | bwet
There are several life studies (see for example http://www.solder.net/stencilquik/articles.asp) which point to higher reliability of reworked BGAs using solder paste vs flux. The theory on the mechanisms which allow this to happen are as follows: 1
Electronics Forum | Tue Sep 25 14:25:30 EDT 2001 | davef
Points in response are: * Microstencils work fine with paste, although they are a little fussy to use. * Never have used microstencils for flux. * Like Hussman, we dab the uBGA into a puddle of tacky flux and then place it on the board. * On contro
