There is ElectroStatic Discharge and ElectroStatic Attraction.
The handbook to implement ANSI/ESD S20.20, TR20.20
in paragraph 5.3.6.1.1 Static Charge Control states:
"Static charge control has become a necessity in many production
environments. By controlling static charge it is possible to:.......
4. Protect against product contamination due to electrostatic
attraction and bonding of particulate to critical product surfaces.
5. Reduce airborne particle levels in some production environments."
And paragraph 5.3.6.1.3 Contamination Control
"Another application of air ionization is to improve contamination
control. High quality air filtration and laminar airflow are used in clean
rooms to lower airborne particle counts and reduce surface
contamination. Filtration efficiency is quite good and most problems
are caused by particles generated by personnel, equipment and
production processes. Unfortunately, these particle sources are
typically located in close proximity to the product.
Balanced air ionization can enhance the ability of the air filtration
system to remove particles from the clean room environment.
Ionization neutralizes charges on critical surfaces and reduces
the attraction of particles to these surfaces. Particles have a greater
tendency to remain in the laminar airflow and then be removed by the
air filtration system."
A number of manufacturers make ionizer blow off guns.
ESD Handbook TR 20.20 paragraph 5.3.6.5.2.4 Point-Of-Use Ionization
"There is sometimes a need to provide static control in a small defined
area or location. This may be done to provide static control within
production equipment, in mini-environments, or to facilitate particle
removal from part of a product. Ionizers used for this purpose may be
blow-off guns or nozzles that work with a supply of compressed air or
nitrogen. They may use either nuclear, soft x-ray or any of the
previously described types of corona ionization technology. It will be
important to choose a method of ionization and cleanliness of the gas
supply that is appropriate to the work area."
Gene Felder
[log in to unmask]
-----Original Message-----
From: Steve Gregory [SMTP:[log in to unmask]]
Sent: Thursday, October 10, 2002 6:58 AM
To: [log in to unmask]
Subject: [TN] Dross particles sticking to soldermask...
<< File: ATT00011.html >> Mornin' all,
I've got a problem here that's giving me a little headache. As you may know,
we got a new wave solder machine not too long ago, an Electrovert Electra.
For the past couple of weeks we've had a problem with dross particles
sticking to the soldermask. It's happening across all our boards, whether or
not we use an OA flux or RMA. Go to: http://www.stevezeva.homestead.com and
look at Dross Particles, and More Dross.
As you can see, it's not that bad, but it's irritating. The particles don't
want to come off without mechanically brushing the board either, and again it
doesn't matter if it's OA flux or RMA. If we run them through our cleaners
without brushing the boards, the particles will remain.
Our pot is clean, it's de-drossed every morning. We're using Kester 2331ZX
OA, and Alpha 16-125 RMA. It's being applied by a OptiFlux ultrasonic spray
fluxer.
The boards look great coming out of wave except for these random bits of
dross sticking to the mask. Solder joints look great, no dross in them at
all...just sticking to the mask.
Got me kind of puzzled...anybody ever have this happen to them?
Thanks!
-Steve Gregory-
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