Hi Ya'll,

Haven't chatted with ya'll since last year! (Yuk,yuk,yuk!) Hope you had a 
good holiday! Me, I stayed home for new years eve...wasn't even able to stay 
awake 'till midnight. Got woke up though from somebody in the apartments I 
stay at cutting loose with some sorta' automatic weapon at midnight...IDIOTS! 
Discretion being the better part of valor, I wasn't about to go tell some 
drunk okie not to be firing his gun in the air. I may do some dumb things 
once inna while, but I ain't STOOPID! (Hehehe..)

Anyways, I've been playing around with some SN96AG04 solderpaste on some 
dummy boards and components trying to dial a good profile in. I took all your 
inputs when I asked about this before to help get me started. I called and 
got a few profiles from a few different paste vendors as well. I've got a 
Conceptronics HVA-70 (the little one, 10-zones, 5-upper, 5-lower) 

First thing I learned was that if I raised the preheat and soak temperatures 
too much higher than I normally do for a SN63 solder, I exhausted all my flux 
activity before all the paste liquified and coalesced into a fillet. I 
wound-up with a fillet that was covered with little teeny-tiny solder 
balls...almost looked like it was cold solder the balls were that small.

So then I lowered everything back down in the preheat and soak regions and 
spiked the crap outta it in the last zones and things started looking better. 
My set points were:

ZONE 1  ZONE 2      ZONE 3      ZONE 4      ZONE 5
140         150         160         175         300     
140         150         160         175         300
ZONE 6  ZONE 7      ZONE 8  ZONE 9      ZONE 10     Belt speed: 25 ipm
 
I plotted it with my M.O.L.E. and was peaking out anywhere from 240-248º C. 
My ramp rates were all under 2º C per second till I got to the spike zone and 
then they went up around 2.4 - 2.8º C per second....one thermocouple at a 
sparsely populated area went up to 3.4º C per second. The joints looked 
better than my first stab...

But I then tried to clean the flux residues (it was RMA), I put the board in 
our MCS-1000 (We run Kyzen Aquanox XJN at a 30% concentration) and the 
residues looked like they weren't touched...some got kinda' cloudy looking, 
but they stayed on the board. I couldn't get them off unless I took an acid 
brush and alcohol to the board. Is this normal? It was like the flux residues 
were polymerized from the heat?

The paste I was using was out of date (that was all I could find to play 
with) maybe that has something to do with it...speaking of which, does 
anybody know where I can get some fresh SN96AG04 paste quickly? Every place 
I've tried says three-week lead time, and I gotta buy at least 10-jars.

TIA,

-Steve Gregory-

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