Solder Frustrations - why won't the $%^ solder go onto the pads?

Just venting a bit !! and maybe looking for tips…

I just did some really neat/nice soldering on the pixelblaze expander board…

I’ve got a temp controlled iron, good quality solder, and new tips that work nicely… the solder flowed onto the pads really nicely, and I got nice little volcano mounds to the pin headers.

Yay, I thought, I’m getting good at this !

Then I try soldering headers to some cheap chinese INMP446 mic boards… the pads and boards are miniature - so I’m working with a magnifying glass… and then the $#$% solder won’t flow onto the PCB board pads… it’s like the pads are solder-repellent.

I brushed a little liquid soldering rosin onto the pads and headers, but still wouldn’t flow. I’ve kind of got it to work - but basically a messy join now.

I think its probably the quality of the copper pads on the cheap boards ? Is there a way to prepare the pad surface better ? Any ideas or experience?

Especially on cheap boards, try cleaning the pads first. There may be some flux or solder resist or other…stuff left on the pcb post-manufacturing. I’ve used alcohol and a toothbrush, and commercial contact cleaner with good results. @wizard and other folks who do more soldering than me probably have better methods.


thanks ! I’ll try that next time !