[Elecraft] Avoiding Broken Wires - Soldered or Crimped

[Ron D'Eau Claire]

-----Original Message-----
...A soldered connection can create something almost too stiff 
or rigid, and can break more easily over time.  A properly 
crimped connection leaves the wire strands naturally pliable 
near the joint, and apparently this is much less subject to 
failure.  I'm sure there is a right way and a wrong way to 
solder a connection properly, but it does seem to me that 
there are a lot of variables in making a good connection 
such as iron temperature, wire size, surface area, etc. etc. 
When I first got my good APP crimper, I tried a couple of 
test connections to see if I could pull them apart.  I 
couldn't!  I've also experienced more than once a soldered 
connection that ultimately just snapped off.  So, maybe I'm 
happy in my ignorance, but a properly crimped connections 
seems pretty effective.

Dave W7AQK

-----------------

I agree, but it's not the solder that's the culprit. In my experience, the
important point is to avoid making any stiff wire flex, especially in one
small area. 

All the wires I've worked with, like those attached to APP connectors, have
plenty of length where any vibration can be taken by the flexible length of
wire, not the stiff soldered part. If some solder wicked into the end, it
needn't bend anyway. It's free to remain rigid. 

One thing that I avoid is allowing a short length of exposed stranded wire
that is *not* tinned between the insulation and the terminal, whether it's
crimped or soldered, when there's no "strain relief" to hold it rigid. Any
flexing of the wire will tend to occur where the wire flexes easiest. In
that case it will be right at the exposed strands, since the insulation
makes the wire stiffer elsewhere. That focuses all movement on those strands
between the insulation and the terminal, whether it's soldered, screwed or
crimped. I have seen many examples where the exposed wires in such
connectors fail.

I don't recall ever finding a single wire broken where it was soldered or
stiffened by solder as long as other areas of the wire was allowed to flex. 

After all, how many computer cables have broken leads? All that I've seen
have stranded wires soldered to terminals. For greatest security, connectors
use a "strain relief" that does more than keep the connections from being
pulled out. The strain relief holds the wires near the terminals rigid so
that all flexing must occur in the cable outside the shell. Nothing breaks
that way regardless of the stiffness of the wire near the terminals. APPs
don't have such strain reliefs, so I'm always careful to ensure there's a
short length of flexible cable between the connector and any bundles or
other restraints I might use.

Ron AC7AC