Electronics Forum | Mon Feb 27 11:06:12 EST 2006 | melby
We are going to start conformal coating PCB assemblies, and I was wondering about cleaning the boards before coating them. Do I need to clean them and if so, with what? We currently us a no clean solder. I am worried about contamination on the board
Electronics Forum | Thu Mar 02 13:04:22 EST 2006 | Chunks
0603 parts at .2mm spacing is pretty easy. But are there any other parts, like fine pitch QFPs? Is your board HASL or something else? Is there resist/mask between all pads? If it's just 0603's at .2mm, then you can probably go 7 mils and get good
Electronics Forum | Thu Mar 02 23:09:20 EST 2006 | praveen39
We need to clean the RMA flux residue on the PCBAs. The PCBA material is ALuminum base(Gold finish)stacked with Rogers Material PCB.Any solvent recommnedtaions? Is HCFC 141b a good solvent (quality & Price). we need to use vapor degreaser and also do
Electronics Forum | Fri Mar 03 14:40:22 EST 2006 | amol_kane
i think a more important issue here would be the reduction ratio. as LF solders have a higher surface tension, they do not flow as well as their leaded counterparts. therefore the stencil design may have to be changed (hence a new stencil) if the red
Electronics Forum | Sat Mar 04 13:26:41 EST 2006 | jldowsey
Something unusual happened yesterday, we reflow soldered two boards with white silkscreen legend, and they came out of the oven with purple silkscreen legend. Not tan or brown from overheating, but purple. The boards were reflowed on their normal pr
Electronics Forum | Tue Mar 07 08:44:10 EST 2006 | billyd
Craig - You should not use the leaded parts, as you are, in all likelyhood, going to see massive voiding. We just went through this same deal where I work, because a manufacturer sent us the incorrect parts. You can go with lead free parts with regul
Electronics Forum | Thu Mar 09 16:14:23 EST 2006 | operator
We are fixing to run a board with both pb and pb-free BGA's..double sided.. The board is RoHs compliant so I could go either way on the solder paste. I was thinking pb-free paste would be the best bet. Any opinions would be greatly appreciated. Th
Electronics Forum | Wed Mar 15 09:28:30 EST 2006 | mapell
Vick I would not think what your seeing is normal. Just guessing without a profile but.... - not reaching peak temperature - not enough soak time or mild ramp to burn away the flux - shortened TAL, not allowing proper time for the solder to wet - lo
Electronics Forum | Wed Mar 15 09:36:43 EST 2006 | vicknesh28
Thanks Marc. I will try the things that u have mentioned. I am guessing if the flux can find its way between the bottom foot of the lead and the paste, there has to be a gap between the solder paste and the lead when reflow takes place. As u have sai
Electronics Forum | Fri Mar 17 07:42:51 EST 2006 | vicknesh28
Copper is the base material for the lead. It's tin/lead plated. I finally got profile. Here are the parameters" Peak : 219 Max (+) Slope : 2.29 Max (-) Slope : -1.94 Time above 200 deg. C : 50s Time 140C - 160C : 126s Additional info : Stencil thic
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