Hi, I'm trying to find a way to connect a AWG24 litz wire to a copper current blade 4.5 x 0.75 x 0.1 inch. Soldering by using a standard solder bolt doesn 't work properly because of the copper heat conductivity/capacity. I wonder if resistance welding or soldering might be a possible way? The process should be capable for large scale production. Appreciate your ideas! Thanks, Michael
Each strand of Litz wire is separately insulated (that's what makes it Litz wire). You have to strip that insulation off before it will take solder. There are chemical dips you can use to do this with some insulation formulations. Consult the wire manufacturer for the recommended stripping method.
To handle the heatsink issue, use a torch (or hot plate) to preheat the copper before attempting to make the joint. The whole thing doesn't have to be brought to soldering temperature. It just has to be hot enough to reduce its ability to sink soldering heat away from the joint. You don't want to heat it so much that it oxidizes. Since heat flow is proportional to the fourth power of temperature difference,
Since I didn't have a clue as to what Litz wire was, here's more than you ever wanted to know about Litz wire:
The term litz wire is derived from the German word litzendraht meaning woven wire. Generally defined, it is a wire constructed of individual film insulated wires bunched or braided together in a uniform pattern of twists and length of lay.
The multistrand configuration minimizes the power losses otherwise encountered in a solid conductor due to the "skin effect", or the tendency of radio frequency current to be concentrated at the surface of the conductor.
In order to counteract this effect, it is necessary to increase the amount of surface area without appreciably increasing the size of the conductor. It is also essential to position each individual strand in the litz construction in a uniform pattern moving from the center to the outside and back in a given length.
Even properly constructed litz wires will exhibit some skin effect due to the limitations of stranding. Wires intended for higher frequency ranges require more strands of a finer gauge size than litz wires of equal cross sectional area but composed of fewer and larger strands.
Polyurethane is the film most often used for insulating individual strands because of its low electrical losses and its solderability. Other insulations can also be used. Litz wires are generally further insulated with a single or double wrap or serving, of a textile-typically nylon-but are also available unserved.