Techies,
We should get some input from the test pins manufacturers...
But, I'll share my experiences until we hear from them.
In any test application using spring loaded test pins, my
best experience was using a stiff nylon brush and a vacuum
with ESD capabilities....
We have universal grid testers for bare boards. The large
test grids on .100", 080", or .050" get filthy with tin/lead,
gold slivers, bits of copper, and routing dust. Our requirements
are to remove the test fixtures, brush the grid (.062" dia.
waffle head pins) with the nylon brush, while vacuuming. Never
use shop air... first of all, it's not perfectly clean or dry.
Secondly, the forced air drives the dust and contamination further
into the grid and electronics.
On our wired fixtures for MDA/In-cirucit regardless of the flux
used... same procedure.... stay away from brass brushes, they are
hard on the gold finish with is very minimal (just a few microns)
and the brass strands are very conductive. Cleaning the test pins
with any type of cleaner is difficult. If the cleaner (solvent) gets
into the barrel it will induce rust or contamination. Even if you
take the test pins out of the receptacles, use an ultrasonic tank
(for rings,etc) with a mild cleaner. It's damn near impossible to
completely remove 100% of the moisture...(even with baking) Within
a few hundred test cycles you'll start seeing higher resistance levels...
then premature spring failures... Just brush and vacuum on a very
frequent basis.. Unfortunately, I've been there, bought the t-shirt,
and have the scars to prove it.
Jim Axton, Corp. Director of Test, DDI
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Earl Moon
Sent: Thursday, March 07, 2002 1:19 PM
To: [log in to unmask]
Subject: [TN] VERY IMPORTANT QUESTION CONCERNING CLEANING TEST PINS
Ok you folks, especially Doug and Brian,
You let this gentleman down and me as well. So much for my appeal but the
question is:
Techneters,
I would like to know if some of you have a suggested procedure for cleaning
of pins for In Circuit Testing, and if is possible to use a solvent, and
what kind of.
Is it possible that flux residues can go into spring machinery? If that
true, how can I clean them of flux residues and how often I must do it?
Regards,
Mario,
I answered knowing you all would come through:
I'm definitely not a cleaning or cleanliness expert. Doug Pauls and Big
Brian Ellis, who contribute greatly to the forum is/are.
I only know flux chemistries are varied. What it takes to clean or
neutralize one, is not right for another.
This is a big issue faced everyday by so many throughout industry, I'm
surprised more people aren't asking your vital qestion.
I would post again or contact someone more qualified as Doug Pauls
([log in to unmask]) and/or Brian Ellis ([log in to unmask]).
I too would be very interested in the chemistry, though it must be
"compatible" and capable of cleaning the indicated flux/chemistry in some
sort of optimized process whether batch or other.
Best regards,
Earl
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