Hey Steve,
Those are some big balls.
Seriously though, could there possibly be some type of mechanical damage to
the conveyor rail/chain or interference with its movement that makes the PCB
"jump" as it moves past this location? Maybe a bolt sticking up just a
little too high?
Good luck with that,
Martin Butcher
-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]]
Sent: Tuesday, October 31, 2006 6:57 AM
To: [log in to unmask]
Subject: [TN] Bizzare Phenomena...
Mornin' All!
This morning I have seen something that I have never, ever have seen
before. It's been a little slow the past week, so we decided to do our
maintenance on our reflow ovens. After we opened the oven up, we found
many, many solderballs laying on the bottom of the oven right around
zone 7 - 8, right at the beginning of the spike zone. Check-out:
http://stevezeva.homestead.com/files/Oven_Solderballs.jpg
http://stevezeva.homestead.com/files/Oven_Solderballs_2.jpg
http://stevezeva.homestead.com/files/Oven_Solderballs_3.jpg
http://stevezeva.homestead.com/files/Oven_Solderballs_4.jpg
We've been having tombstoning problems when we've run the two lead-free
jobs that we have here. I've been working with the paste vendor sending
my profiles and plots, but I haven't been able to solve the problem. The
solderballs in the oven are lead-free solderballs.
We are using a Heller 1809, and my profile set-points are:
120 140 160 180 190 200 230 240 250
120 140 160 180 190 200 230 240 250
Belt speed 26 in per min
The paste is a SAC 305 with a water washable no-clean flux. I think my
profile is pretty reasonable, and the last board we ran is pretty
standard, .062" thick, with no bizzare copper planes. The board finish
with both jobs has been ENIG. The last job I ran we were tombstoning
0805's, the one before that we were tombstoning 0402's. With both jobs
we've had major tombstoning problems. I've slowed the beltspeed down,
sped it up, ramped up slower, ramped up faster, changed this, changed
that, but still haven't resolved my tombstoning.
Of course, I'm the only one that's having this problem according to my
paste vendor...
I wouldn't have imagined that I would see the solderballs in the oven
like we have...
Have any of you ever seen something like this before?
-Steve Gregory-
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