Applications > Medical Device > Bonding
Bonding Dissimilar Materials
One of the most prevalent concerns when bonding materials is how to get a strong bond between mismatched substrate surfaces. Generally, when bonding like materials, there are adhesives available that will strongly bond the two surfaces at the interface of the substrates. However, in many manufacturing scenarios the need to bond different materials with very dissimilar physical and chemical properties frequently arises. For example, a reasonably rigid material such as polycarbonate (PC) may need to be bonded to a more elastic polyethylene (PE) material. Since the chemical makeup of these materials is quite different, they will tend to bond differently to various adhesives. A certain adhesive may bond well to the PC, but not well – if at all – to the PE, and vice versa.
There are methods to chemically treat the surface of one or both of the materials using primers, or other mechanical means, such as sanding, to get a strong adhesive bond. While many of these chemical methods work quite well, they require the use of materials that may expose the manufacturer to dangerous or toxic matter. Such materials may also require expensive or time-consuming disposal methods. Most importantly, many toxic or dangerous materials cannot be used in the manufacture of medical devices that are implanted in the human body.
Plasma has a proven application and manufacturing history helping bond dissimilar materials including metals and various plastics. It can reduce manufacturing time and costs by potentially eliminating the need for primers. Stronger bonds from plasma can be a combination of several plasma processes. Depending on the process gas selected, plasma can clean, activate and roughen the surface to optimize the strength and quality of the bond by enhancing the physical and chemical aspects of the bond.
The figure below is an example of bonding a commonly used Polyurethane to High Density Polyethylene using various adhesives (Silicone (RTV), Cyanoacrylate (CA) and 2-Part Epoxy (2-Part)). Plasma substantially improves the adhesion as demonstrated in shear and T-peel tests for all of the adhesive systems. The magnitude of the improvement is a function of the substrate and adhesive types, the plasma process, and plasma configuration.
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Medical Device Applications Team
James D. Getty, Medical Device Market Manager
Getty leads March’s Applications Engineering and Business Development activities, including the Marketing activities supporting the business’ Semiconductor, Printed Circuit Board, and Life Sciences market segments. Getty joined March in 2000. Prior to March Getty has held positions in the semiconductor industry. Getty has a BS, Chemistry from the University of California at Irvine and a PhD in Physical Chemistry from the University of California at Davis.
David Foote, Sr. Staff Applications Engineer
Mr. Foote has an extensive background in chemical vapor deposition (CVD) with a focus on plasma enhanced CVD. Prior to working with March he developed processes in the semiconductor and semiconductor equipment industries. He holds a B.S. degree in Chemical Engineering from the University of Cincinnati. Mr. Foote has been granted over 35 patents.
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