Coated wire for medical applications
Polymer coatings and metallic electroplating can be applied to many medical grades, such as Sandvik F562, Sandvik 304VM, Sandvik 316LVM, and other alloys depending on the medical application.
Coating the wire prior to incorporating it into a device provides more complete coverage over the entire surface area of the wire, rather than strictly on the outside of a device.
The polymer coatings can provide a dielectric barrier when the wire in the device is used to transmit electrical signals or provide electrical current for medical therapies. Polymer coatings can also be used for ionic barriers, enhanced corrosion resistance, providing a lubricious surface and/or be used for lead identification.
Electroplated coatings can be used to enhance the joinability of the base wire grades (i.e. solderability, weldability, ultrasonic bonding etc), increase the conductivity and/or provide a more noble surface.
PTFE is used as a coating on fine wire for either dielectric protection or to enhance lubricity. Aqueous-based PTFE is typically applied to precious metal alloys such as PtIr of less than 0.100 mm and is clear in color. Solvent-based PTFE is applied to the wires in the 0.1 mm to 0.8 mm range for applications such as catheter guide wires. The solvent based PTFE grades provide a balance between good adhesion and good lubricity in these applications. They are supplied in various colors such as green, blue, grey and clear.
Electroplating and polymer coating can be performed on square and ribbon wires in addition to round wires.
Sandvik's speciality is gold plated copper (0.02 mm and larger) but plating on a wide variety of other metals is possible (i.e. nickel, nickel chrome, silver and copper alloys). Nickel plating and/or a nickel interlayer is also possible.
Multifilar coated wire
Polymer coated wires can be combined in multifilar configurations such as bifilar, trifilar and quadfilar. Multifilar wires simplify wire handling when multiple signals are required for a device. Multifilar wire cables can be provided in a flat or bundled configuration and eight different colors and multiple shades of these colors are available for easy identification.
Common uses of multifilar coated wires are bifilar pairs for medical microthermocouple applications and quadfilar goldplated copper leads for sensor signal transmission.