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Enhancing Thickness Uniformity for Medical Device Coatings

Surgeons inserting a stent during heart surgery.

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Medical devices often require thin film coatings to optimize performance and longevity, while also ensuring patient safety. Because these devices often feature unique properties compared to “normal” substrates, such as a completely curved or flexible structure, they have challenging thin film deposition process requirements.

Magnetron sputtering with an inverted cylindrical cathode is one thin film deposition design that offers several key benefits for medical applications, especially complex, 3D devices requiring uniform coatings.

Medical Coatings Requirements

For medical implants and other medical devices, there are a few main thin film requirements:

  • Biocompatibility: Manufactured devices and tools must be biocompatible in order to enter the human body. Biocompatible hard coatings help ensure that implants are safe for patients. They also protect the device itself from corrosion, since implants are in direct contact with human tissue and organic molecules such as proteins.
  • Radiopacity: Some implants, such as cardiac stents, are implanted while using an x-ray imaging technique (e.g., angiography or radiography. However, some of the coating materials used for the stents, such as Nitinol, are difficult to view with x-ray imaging, as they are essentially transparent to x-rays. A coating that is “opaque” does not allow the x-rays to pass through, enabling the surgeon to more easily see the stent and ensure operational success.
  • Uniformity: Uniformity is an absolute must for any medical device or implant. Uniformity helps ensure performance, which is critical for applications that are as sensitive as these. If thickness is not uniform and the coating is too thin in one area, it could compromise the biocompatibility of the entire device.
  • Flexibility: Certain medical devices, such as stents or catheters, need a high degree of flexibility so that they can be pushed through vessels with little resistance. Otherwise, they might cause discomfort or pain, or even harm the patient.

How an Inverted Cylindrical Magnetron Solves Challenges

Because of its unique design, an inverted cylindrical magnetron (ICM) can achieve extremely high uniformity, without making for an overly complicated thin film deposition process. The substrate is placed inside the cylinder, and the sputtering direction is inward. This makes it possible for the entire surface of the substrate to be coated simultaneously, even if the substrate is a curved or complex 3D shape, without additional process steps.

As an example, Denton’s patented VisTa nanostructured tantalum coating process, using our Isoflux ICM magnetron, is designed to meet all of these challenges for Nitinol stents. This process provides a uniform, 3D coating over the entire stent. The coating enhances radiopacity for surgical success, while maintaining biocompatibility and flexibility for long-term viability.

This technology opens the door for a more efficient, uniform coating process for all types of medical implants and devices. With ICM sputtering, you can match the unique requirements for these devices on a robust, standardized deposition platform suitable for the medical industry.

Invest in a Fully Integrated, Repeatable Solution

Denton Vacuum’s Isoflux inverted cylindrical cathode delivers the repeatability and uniformity needed for sensitive medical applications, even on complex or curved surfaces. We can deliver a full sputtering system design that seamlessly integrates the inverted cylindrical cathode and achieves excellent precision for biocompatible hard coatings in real-world medical device applications.

Unlike planar configurations, which require complex movement and masking in order to coat complex surfaces, our ICM design enables higher deposition rates and better process efficiency. The inverted cylindrical cathode is completely compatible with Denton’s Discovery sputter module, giving you the process control you expect from a mature production platform while ensuring you are meeting difficult medical device requirements.

To learn more about how an inverted cylindrical cathode can be integrated with your thin film deposition process, contact us.