Hi
Just to add to the amazing answer from @geirandersen
If you want to remove oxidation from SMD components cleaning with isopropyl alcohol and reflowing the solder joints with a little solder and flux makes the world of difference
Here’s a example of what to expect:-)
Before isopropyl alcohol,Flux and solder
[image|2833256]
After isopropyl alcohol,Flux and solder
[image|2833258]
Hopefully this helps
Any questions please ask
Thanks:-)