Since solder is such a poor conductor, why use it?

Almarg, I doubt seriously if the solder you and I have access to is anything like that used in the military.

Tbg

I spent 20 years as an electronic tech in the USAF and there was nothing special about the solder we used. Yes I was soldering components on boards as well as connectors used in aircraft. Now maybe NASA uses something special, but I doubt it.
A good solder joint is going to last. It just has to be done properly. That's what quality control is for.

I guess the military need not use lead free solder. The EU has largely forced the move against lead in solder. Lead is a poor conductor as is tin, but lead tends to not crack. Welding copper to copper or silver to silver would mean no loss of conductivity.

TBG
"Almarg, I doubt seriously if the solder you and I have access to is anything like that used in the military."

The military and NASA specs call out fairly ordinary solder!

I worked in QA, on military and aerospace electronics.

Don_c55, as I know a guy who worked at NASA who told me of $1000/foot wire, I suspected what you said. Thanks.

I also know that systems for better grounds to Earth, weld the copper wire to the copper pipes buried deeply into the ground.

I used to manufacture my own cables and quickly realized that solder was no good...I crimped all my cables