Julien:
Your immersion depth should be based on your average board thickness. The
1.93mm depth you gave, or approximately .076 thousandth inch, seems pretty
deep. Our average board thickness is around .060" thousandth inch. Your
variation may be sump pump oscillation. Some of the newer machine can
maintain a relatively steady wave, however, many of the older machine have a
definite oscillation (wave actually moves up and down). As far as
parallelism, that also can be affected by the oscillation of the wave and
sump pump design. If the pump is on the inner side of the pot, the outter
side will be deeper than the inner side. This can be adjusted by lowering
the inside rail. You want your rails parallel to your wave and not parallel
to ground. Even the best machines have an offset. Newer pump and baffle
designs have improved rail offset or parallelism tremendously. If you are
using fixtures with your boards, to prevent flooding, to support your
boards, etc., then wave depth is not as critical. If you are not using a
fixture then you should be careful of immersion depth to prevent board
flooding. Check your board thickness. A good rule of thumb is to have the
wave at 60% of the thickness of the board. That leaves 40% for pump/wave
changes when running a board without a fixture. If your pump/wave is
oscillating more that that 40%, you may have a flooding problem.
Keep in mind when you are evaluating your pot that the solder pot should
remain at a certain level. Also the time of day you are taking your
readings. If you take your readings at morning, noon, and end of day
without adding solder, then your readings will be different and the trend
should show lower numbers as the day progresses and you run product. If you
don't have an automatic solder feed then solder level should be checked
often. This will affect how your pumps react. By this I mean the chosen
RPM will need to gradually be increased as the day progresses and you run
product. Checking your solder level in the pot is the way to go, otherwise
you would have one heck of a process to write based on some kind of linear
scale as the work day progresses. Plus operators would be constantly
changing the RPM to keep up with solder use. Newer machines with auto
solder feeds can keep the pot level reasonably constant. As far as how long
the product is in the solder wave, usually a good rule of thumb is 3
seconds. Over 5 seconds is getting marginal for many components. Hope this
helps a little bit.
Ron Hollandsworth
-----Original Message-----
From: Julien Bouchard [mailto:[log in to unmask]]
Sent: Wednesday, July 11, 2001 10:20 AM
To: [log in to unmask]
Subject: [TN] WaveRider results on solder wave
Hi everybody,
We start using a waverider for monitoring two wave soldering
machine. We
have made some pretest run during one month. Our main concern is about the
parallelism and the immersion depth of the solder. The parallelism is
between -0.2 sec et 0.4 sec ( main wave ) and the immersion depth is between
1.47 mm and 1.93 mm. Our main question is about the variation we see not the
absolute value. We have a standards deviation of 0.2 sec for the parallelism
and 0.12 mm for the immersion depth. Since we have no real point of
comparaison, we are unable to say if this it's ok or too much. We want to
know if other person use the waverider and which variation do you read from
the immersion depth and the parallism of the wave solder. Thank you.
Julien Bouchard ing. stag.
Matrox - Spécialiste de procédés
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