I have been struggling to solder tinned stranded wire to gold-plated pin headers. The solder doesn't seem to adhere to the pins.
I have tried lightly abrading the pin surface and cleaning with Isopropanol, applying liquid flux, increasing the iron tip temperature to 400°C!
Eventually, the wire attaches using the high temperature however, sometimes not very well. The pins also melt the plastic support material and come loose.
These are the pin headers:

Any suggestions?
