What is the right welding and bonding technology for your medical device? Part I: Under-the-Skin

The newest generation of under-the-skin devices, like replacement heart valves and neurological implants, has a Class III designation, requiring 100 percent hermeticity and joint integrity. To achieve that, manufacturers must incorporate the right welding and bonding technology.

Time consuming and highly complex
Take the task of seam welding, an important step to ensure hermeticity and device lifetime. Device manufacturers have no shortage of options, including plasma welding and electron beam welding. Both these processes are relatively clean and yield good results, but are time consuming and require highly complex systems with components like vacuum chambers.

Laser welding, usually quicker
Another option is laser welding, which provides equal or greater accuracy while offering important advantages: First, no time-consuming vacuum chamber or the like is involved. Laser welding can be done in an inert gas atmosphere, generally nitrogen-based. Laser welding is usually quicker than other options and creates very reliable joints. Medical device manufacturers are now opting for automated laser welding as a way of driving costs down and improving welding process control.

Locate optimal position
Also, advanced laser welding systems often feature vision systems, which enhance automation capabilities. Vision system cameras recognize parts, identify the weld areas, and locate the optimal position for the laser to begin joining parts. For example, many pacemaker parts are pressed, not machined, so the location of the interface varies. Manual alignment can take several minutes for each device. Vision systems and bespoke software algorithms on AMADA WELD TECH Laser Welding Systems cut the task down to a few seconds.

Laser is also more flexible. Take the example of hypotube production. The process requires micromachining features into a tube, also known as a catheter tip. The tip is then welded to another wire or tube, known as the hub. Laser machines can both cut and weld the metal. In fact, stand-alone systems can perform marking and ablation of coatings, too. Laser welding systems are effective at welding certain types of stents, drug pumps, implantable valves, and other life-supporting devices.

Or use resistance welding?
It is important to note that laser welding is not necessary for every invasive device, or even for every joint that goes to make up that device. To weld the batteries inside pacemakers, for example, resistance welding is commonly employed. In Part II of this blog, we will examine what welding or bonding technology best suits devices that are not under-the-skin, but rather are wearable. How are wearable monitors and smart watches best held together?