In a message dated 6/14/99 1:05:48 PM Pacific Daylight Time,
[log in to unmask] writes:
> Hello to All,
>
>
> I am looking for anyone who has knowledge of any standard on Mod Wires
> besides IPC 610B, IPC-771,7721 or IPC-700.
>
> These standards only cover briefly about the particular item I am
> looking for, which is STAKING MOD WIRES.
>
> Particularly, how close one can place glue to a solder joint or
> component. If it can touch these or lay on top of or any other
> situation.
>
> If anyone has any experience in this area or has any opinions, your
> response would be much appreciated.
Hi Aric!
The IPC-700 does have some good guidelines about jumper wires, but what it
all really boils down to is; Form, Fit, and Function. Obviously, the jumper
is either there to correct a design problem, or to upgrade something from an
old design. The goal is to effect the rework so that is will have an expected
reliabilty that is the same as the product would have without the
jumpers...with jumper wires, you're just making a trace that's not there.
The guidelines about staking wires is pretty good, stake the wire every inch
and at all 90-degree turns. What you use to do that is very operator
dependant to make it look good. Loctite has the ol' standby called "Tak-Pak",
but I've found that many operators haven't yet mastered the skills to use it
in such a way to make it look really good. They'll get the wire down, but
there will be "Tak-Pak" all over the place, fingerprints of "Tal-Pak", and a
white-ish haze at many of the points were the staking was done.
My preference is hot-melt adhesives, and a good operator...I can''t stress
that enough. This is an operation that takes a skilled person to do this
where it looks really good, not just anybody has the "Touch" to do it well...
As far as how close I would put any staking material to a solder joint, as
close as you want, I wouldn't recommend getting it on the joint though. I
also try to keep the wires directly on the PCB and not go over components, as
well as to try and keep the wires from going over each other (crosstalk and
all), as well as trying to keep them as short as possible so as not to induce
any sort of signal delay.
Good jumper wire work is really an art form, especially when you have a bunch
to do on a board, but I've worked with some operators that can make them look
like it was actually a part of the design of the assembly...you look at the
finished board and go whoa! That's awesome!
Hope this helps!
-Steve Gregory-
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