Fine Wire Laser Stripping
One only class of polymer insulation that cannot be effectively stripped with the Mercury system is bonded enamel wire. The wire is dipped in an enamel liquid which forms an extremely thin, but extremely tough insulation layer. There are many formulations, but polyimide is a common one. The carbon dioxide laser may be able to remove some of the enamel insulation, but almost always leaves a thin residue of a few microns. This prevents effective soldering in most cases.
The Odyssey range of laser wire strippers utilize ultra-violet laser technology. A key feature of this laser is that the enamel insulation is very strongly absorbing at this wavelength and is immediately vaporized. Each pass of the laser removes a fraction of the insulation and typically four or five passes are required to remove the insulation fully. The laser ablates the insulation right down to the conductor leaving a perfectly clean surface for connectorization.
Very fine wire is often coated with polyamide and/or polyimide coatings - often known as enamel insulation. These very thin coatings are chosen for their high temperature performance allowing high densities of wires to be used in coils. Enamel insulation is also used where very thin coatings are needed to minimize the overall wire diameter - for example for medical applications.
Enamelled wire is used in many applications. Larger gage wire is used in motors and transformers. Smaller gages are used in chokes and precision windings such as those found in precision medical power tools. Enamel coating are also very common in medical wiring used within catheters. To aid the connectorization of these very fine wires (<<30 AWG) they are often ribbonized in bi-filar, tri-filar or quad arrangements. Bi-filars are often used as thermocouples in catheters to measure the temperature of the adjacent tissue when procedures such as RF ablation are carried out.
For ribbonized enamelled wire, it can be desireable to remove a window of insulation from just one of the filars of the ribbon. See precision wire stripping for more information.
Example of the precision that can be achieved with the Odyssey UV laser wire stripper. Different widths of insulation were ablated in sequence. Note the sharp transitions at the stripping zone.