Complements of Chrys Shea ......ACI

The purpose of a turbulent wave is to slap solder everywhere on the bottom
of the circuit board.  The turbulence upsets the surface tension of the
solder so it can seep into all the little nooks and crannies around chip
components and other SMT devices.  The laminar wave maintains a smooth, even
surface tension to fill holes and snap off solder bridges.

A standard chip wave has a closed nozzle with holes in it.  The turbulence
is created when the solder tries to shoot up through the little holes.
Increasing or decreasing the turbulence is achieved by raising or lowering
the pump speeds, and therefore the amount of solder that is contacting the
circuit board.

A rotary chip wave has a nozzle with a long open slot in it.  Inside the
nozzle is an auger that creates the turbulence.  Increasing or decreasing
the activity of the wave is primarily managed by changing the RPM's of the
auger, not the pump.  So you now have two separate control mechanisms for
this wave.

There are a couple of advantages to having a rotary chip wave.  Because you
can increase the turbulence by raising the auger speed, you are not
necessarily pumping more solder (and therefore heat) across your board and
risking top-side reflow.  And because the orifice is a slot, it is much less
likely to get clogged by dross and cause skips on the bottom of the board.
When we had standard chip waves, our operators had poking devices so they
could reach in and clear the clogged holes of dross.  That's when they were
paying attention and seeing the skips on the bottom of the boards.  Never
had a dross clog on the rotary chip.  Never had a problem with solder skips
either.

The disadvantage of the rotary chip it that it tends to generate more dross.
Because of its high activity, more molten solder is exposed to the
atmosphere, and therefore, more dross is generated.  Not an issue if you've
got an inert environment.  In my opinion, it's not an issue even if you
don't.  Dross is much cheaper than rework.  And most of the waves have
sensors on them so they are not running if there are no boards approaching.

Having run both types of chip waves, I believe that rotary is the best way
to go. Thanks Chrys

Caldon W. Driscoll
Equipment Advisory Board (EAB)
Coordinator
ACI/empf
One International Plaza Suite 600
Philadelphia, PA 19113
610-362-1200 X 272
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*-----Original Message-----
*From: TechNet [mailto:[log in to unmask]]On Behalf Of Smith, Gary
*Sent: Friday, July 28, 2000 8:52 AM
*To: [log in to unmask]
*Subject: [TN] Wave Soldering Types
*
*
*I'm looking for details on Turbulent Chip and Rotary Chip Wave soldering.
*Specifically, how they work and what they're used for.  I have information
*on the Lambda and Omega Wave types but if anyone could give me some more
*info or references for these it would help.
*
*Regards,
*
*-Gary Smith
*
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