3 Microwelding methods in medical components and devices

Implantable cardiac rhythm devices, cochlear implants, and neurostimulators are some of the most complex medical devices. Not only do they comprise all of the materials of electronic assemblies, they require the biocompatibility and extreme reliability required for human use. The selection of the outer-case materials is typically driven by the ability to provide a hermetically sealed enclosure, and long-term corrosion resistance. Typical materials now in use include 316L stainless steels, MP35N, titanium, niobium, and alloys of platinum–iridium. Microjoining for these materials and applications includes the welding of pacing lead coils to terminal pins via resistance and laser-spot welding, laser-seam welding thin titanium housings, and spot welding of thin electrode rings to interconnect wires by various welding techniques. This chapter will review key aspects of material choices and the typical joining processes for medical devices.