This is about the material, not the size. If the solder just doesn't stick, it doesn't matter how big it is. Common solder is, of course, designed to stick rea

This is about the material, not the size. If the solder just doesn't stick, it doesn't matter how big it is. Common solder is, of course, designed to stick really well to copper. Which it does. To solder more exotic things, you probably need a completely different alloy.