4awg lug terminal too big for 4awg wire ?

[Hedges]

Both water-cleaned and no-clean flux are used for PCB

Use of Flux in PCB Assembly No-Clean Flux vs. Water Soluble Flux

Bittele provides Turnkey PCB Fabrication and Assembly Services. It explains the difference between Water Soluble and No-Clean Flux. It uses No-Clean Flux but can accommodate Water Soluble Flux upon request.

www.7pcb.com

"Water Soluble Flux is a very aggressive cleaner and oxidizer. It is much more reactive than No-Clean Flux and is thus a stronger cleaner. Though this provides excellent soldering results it also has a downside. The flux residue from water-soluble flux is quite corrosive after soldering and needs to be completely removed, this is done by very thoroughly washing the boards with distilled water. Even slight residues can cause failures in the board over time due to their corrosive nature."

My preference for an analog application was no-clean flux, to be cleaned off with an IPA based cleaner.
I wanted 10 Gohm surface resistivity. Without cleaning, no-clean flux showed 30 Mohm.
For low voltage digital, leaving no-clean on the board is OK.

Since stranded wire is going to wick and trap materials, no-clean is probably best for terminals.

 

[sunrise]

Thank you all for the information - super helpful. I also want to give an update on WindyNation lug size - I got some 6awg lugs from them and they are much better fit.

 

[time2roll]

I get these provisions here: https://www.genuinedealz.com/collections/tinned-copper-cable-lugs/wire-awg-size_4-awg

Lugs seem to fit the wire correctly.