Kevin,
I must ask, what kind of wires do you use? We have pretinned miles and
miles of wires for decades, NEVER heard about the problem you mention.
Millions and millions of pretinned wire ends have passed. We use all
gauges, from mini signal wires to 500 A power cables, teflon, tefzel,
polyeten, PVC, rubber, silicon, kapton...a sortiment from nearly all
brands, and not one remark about what you say. We use both fluxes and
have done for years. Are you in the space industry?
Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Kevin Glidden
Skickat: den 2 december 2005 23:02
Till: [log in to unmask]
Ämne: Re: [TN] Pre-tinning wire & components
By reviewing J-STD-001, it appears I may have answered my own
question....
J-STD-001C (which I was previously trained to) stated that for Class 3,
you
must use levels L0 or L1 of RO, RE, or OR types BUT you can use type H
or M
for tinning of terminals, solid wire, and sealed components. I have
apparently incorrectly read this as "you can use type H or M for
pre-tinning
only".
This may have been a common interpretation, as the new J-STD-001D
removes
the verbage around type H or M for tinning, and now specifically states
"Type H or M fluxes shall not be used for tinning of stranded wires"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kevin Glidden
Sent: Friday, December 02, 2005 4:36 PM
To: [log in to unmask]
Subject: [TN] Pre-tinning wire & components
Hello all,
Question on pre-tinning of components and wires. We are in a debate
here.
Is it desirable to pre-tin wires and components with a water soluble
(high
activity) or an RMA (low activity)?
My position is that water soluble (high activity) is the preffered flux
type
over RMA to provide better pre-tin and also ease of cleaning.
Others are arguing that there is significant risk in using the water
soluble
due to the corrosive residues, particularly if they are able to wick up
the
wire and under the insulation. They state rosin is to be used for
pre-tinning to mitigate that risk. My issue with this method (aside from
the
lower activity level potentially yielding a lower quality pre-tin) is
that
our termination process can call for either rosin flux or water soluble
flux, depending on the application or product, and I am concerned that
any
rosin residues from the pre-tin (more difficult to remove than water
soluble) could negatively impact the termination solder joint.
Another thing to consider is that we stock pre-cut and pre-tinned wires
at
point-of-use, so there could be a significant time-frame between
pre-tinning
and termination. Depending on your view, this could be time for the
water
soluble residue to work it's corrosive magic or for RMA residue to
nicely
harden.
Thoughts?
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