Hi Joe,

        You bring up good points.  The reason we use finger cots is for
contamination.  But, the standard "pink" ones are not static dissipative.  We
use standard and static-dissipative or none at times depending on the
application.  None are used just as you said when you can't tell you've got
the component in your hand because it's so small or fragile.  Then post
cleaning is key.

        There is one more interesting thing I read some time ago and wish I
could remember who to give credit to.  But, there was a study done on how
often the cots needed to be replaced in order to maintain cleanliness.  Now,
if I remember right, what came out was changing frequently was almost as bad
as not changing at.  The reason was the sweat on the other hand.  What fingers
are you going to use when you put on the first cot?  Now, how about the other
hand?  Contamination and cross contamination.  The other thing that I think
came out was the contamination level dropped as more product was
handled...makes sense too as the initially fixed level of contamination is
getting dispersed with each touch.

Anyway, for the most part we use them.  The static dissipative ones not so
often.  But, we work under ionized air.

Glenn

"Kane, Joseph" <[log in to unmask]> Wrote:
|
| Technetters:
|
| Our new Space customer may be pushing us to use static-protective gloves or
| finger cots for soldering and assembly operations.  We prefer to continue
| our current practice, having operators exercise due care and handle product
| by the edges only, and use gloves only for hot things or when using some
| chemicals.  This has worked well for all of our high-rel product, including
| flight controls and aircraft engine controls.  When we do 10-day humidity on
| conformal coated assemblies, we occasionally see mealing patterns in the
| shape of fingerprints, but not very often.
|
| Some of the problems we see with the alternatives, in approximate order of
| importance:
|
| 1.  Gloves and finger cots compromise dexterity and tactile sensitivity.
| Maybe not much, but some.  Productivity suffers, defects go up, and maybe
| some things get dropped that normally wouldn't.
| 2.  Contaminants deposit on gloves or finger cots, obviating any benefit.
| By contrast, when operators get flux or adhesives on their bare fingers,
| they can feel it, and they go wash their hands, or at least wipe them on
| something.
| 3.  Finger oils still get on gloves or finger cots.  You have to handle them
| with bare hands to get them on, and then everyone's nose needs a scratch
| once in a while.
| 4.  Operators hate them because they are cumbersome and uncomfortable.  Some
| would say tough luck, and if there were good reasons we would force the
| issue, but as it is this looks like another compliance issue/audit trap that
| we don't really need.
| 5.  Over time, some people develop sensitivity to latex, maybe even nitrile.
| 6.  They cost money.
|
| Like bunny suits or respirators, I don't know why anyone would use these
| things unless there was a good reason.  Anyone out there have any
| experience, good or bad?
|
|
| Joe Kane
| Lockheed Martin Control Systems
|
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