Laser welding of active implantable medical devices (AIMD)

Specializing in the design and manufacture of active implantable medical devices (AIMD) under contract, Cisteo Medical relies on cutting-edge technology to ensure the laser welding and sealing of implantable titanium housings , used for example in neurostimulation or cardiac stimulation .

The principle of laser welding is to bring energy to the junction of two parts so that they melt and weld. Generated by a laser beam, the energy is concentrated in a single point and the fusion is thus carried out very locally, which avoids overheating of the entire component. No deformation is to be deplored since only the welding area is affected. To obtain a watertight weld, several successive welding points overlap and create a bead.

This process works without the addition of material and therefore has no impact on biocompatibility . Note that laser welding can be carried out on different materials: stainless steel, titanium, titanium alloys, etc.

In order to guarantee a reliable and repeatable solution, Cisteo Medical has integrated a 5-axis laser welding installation into the clean room. The latter ensures the production of welds in a rotating, flat or complex trajectory manner. The machine moves along 5 automated axes and a manual axis: in addition to the X, Y and Z axes, there is the rotation axis of a mandrel and the pivoting of the laser beam head on itself. Coupled with a spacious work area, this dexterity allows in particular the welding of complex implantable titanium cases.

Thanks to the flexibility of this installation, it is possible to produce quantities ranging from a few prototypes to large series, while maintaining the same repeatability . Producing prototypes as close as possible to the final device makes it possible to remove many technical obstacles in the very early phases.

With laser power of up to 2 kW, flexible weld geometries and high weld depths are easily achieved, an important criterion for ensuring mechanical strength and tensile strength of the part, for example. In addition , welding under inert gas limits oxidation of components as well as intermediate storage in a dry cabinet .

The enclosures are closed in two stages: a spot weld is first carried out in order to hold the components without altering them. Then a bead weld ensures a continuous connection between the components, a coverage rate of 70% allowing the required sealing to be achieved.