Volks, I've been "soldering" stuff for the past 37 years.  Probably the
best advice I received from my mentor was that mechanical connections =
crimping, twisting, hooking AND electrical connections = lots of
mechanical contact and/or soldering!  One should not depend upon a
soldered connection for mechanical connection, although, in printed
circuit board construction, one has to.

If one has experienced a "brittle" nature to their soldered connection,
one has experienced a "cold" solder joint.

"Flux" is NEVER necessary in typical electrical wiring soldering!!!
Rosin is NOT "corrosive", in any way!  I have some home-brew & radio
kits I built back in the 60's and later and I defy anyone to find any
evidence of any rosin-induced "corrosion" in any of these pieces of
equipment!  In fact, me grandmother's '37 Philco AM-SW radio still works
fine and, virtually, everything in it is "soldered" together.

"Most" connectors you might suspect look like aluminum, today, are
simply tinned copper.  I buy ALL my typical connectors from a
"aluminum/copper/steel" yard.  They have the "crimp-on" connectors in
five gallon buckets.  When one is used to it, one can determine the
cheap, useless aluminum connectors from the tinned copper connectors via
"feel".  Just "try" soldering aluminum and one will know what I'm
talking about.

"Push-on" crimp-on connectors are made for one purpose - convenience.
ANY time I use one, I crimp it for mechanical strength and solder it for
electrical integrity.  I live with the friction fit.

Any "splice" I make in electrical wiring, I trash the little plastic
guard, slide a piece of heat-shrink tubing on, use a crimp connector,
solder it, cover the uninsulated wires with silicone, slide the
heat-shrink over that area and contract it.  Even within the vehicle.

I can't even comprehend the use of any "flux" in electrical wiring!  It
makes me worry that some folks are even using acid-core solder for
wiring copper!!!

BOB - WA4RRN
'85GL - "Bourgeois"
SouthCentralTennessee