Dear Jim,
I have toured many plants in my career and have only seen one where they
actually used these things - and then I wonder whether it was just for the
tour!

I know in the Nortel plant I used to work in that the staff were drilled
about picking up the bare boards by the edges.  We had very good assembly
yields.  And unless you deliberately fingerprinted a circuit board and
followed it through the manufacturing process and then did pull/shear,
x-sectioning or thermal cycling how would you know?  Most of the evidence
would be burned off/buried and you would not know the cause in most cases if
a problem had occurred.  And of course solderability is not the only problem
- there is also potential surface insulation resistance, etc. issues.

Personally I think banning eating and drinking from the shop floor (also a
health issue!), reinforcing common sense personal hygiene basics and
educating the staff on the importance of picking up components and boards
without touching PTH's, pads (pick up boards by the edges) and component
leads is sufficient for most applications.  I can't speak for the space guys
or in-body guys.

regards,
Bev Christian
Research in Motion

-----Original Message-----
From: Jim Kittel [mailto:[log in to unmask]]
Sent: May 31, 2001 9:08 AM
To: [log in to unmask]
Subject: [TN] Cotton Gloves/Finger Cots


Fellow TechNeters:

We are questioning the need for finger protection against contamination
during CCA assembly.  The story has always been body oils and salts
deposited on the solderable surfaces will undermine solderability.  Since
our process uses robust RMA fluxes and SMT pastes (at the expense of
cleaning) and since much of our assembly (especially SMT) is automated, I
would like to re-visit that issue.

I have heard rumors of a few companies not using any finger protection and I
have heard of another using finger protection in assembly but not in the
stockroom area.  A search of the TechNet archives provided some interesting
comments on finger cots and gloves, but nothing relating to the detriments
of not using them.

I would appreciate hearing your comments on 'if' and 'where' you are using
either finger cots or cotton gloves (or both) and also if there are any
substantiated cases where finger contamination actually caused solderability
issues on real product.

Thanks,

Jim Kittel
Sr. Process Engineer
L-3 Communications

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