I have made quite a few keyboards (including handwired) and a few other electronics projects with lead-free solder and it has never been an issue. I use lead-fr

I have made quite a few keyboards (including handwired) and a few other electronics projects with lead-free solder and it has never been an issue. I use lead-free solder with a resin core, set the iron to the recommended temperature, and make sure to tin the tip.