Originally Published November 2000

HOTLINE

High-Nitrogen Implantable Steel Is Produced Using Single-Melt Method

Stainless steel with a high nitrogen content is the most recent addition to a range of stainless steels suited for orthopedic implants, fracture management systems, coronary stents, and related applications. Developed by AB Sandvik Steel in conjunction with Sandvik Metinox (Sheffield, UK), Bioline High-N surpasses the mechanical properties and corrosion resistance of widely used 316LVM, according to U.K. technical sales manager Stephen Cowen.

Bioline High-N is supplied in various tensile strengths in wire, bar, and tubular forms.

To comply with the cleanliness requirements of ISO 5832-1 (316LVM) and ISO 5832-9, materials are traditionally refined by means of vacuum arc remelting or electro slag remelting. Although ISO 5832-9 only recommends remelting the material, the practice is so ingrained that many implant manufacturers consider it to be mandatory. Sandvik has adapted the argon oxygen decarburization process, generally used to melt bulk stainless steel, to the processing of Bioline High-N. By using this method, Sandvik is able to produce material on a large scale that meets all the requirements of ISO 5832-9 without the need for further refining.

"Sandvik is able to eliminate the secondary remelting stage of manufacture thanks to very tight inclusion control during melting, valuable expertise gained from over a century of bulk stainless-steel production combined with extensive investments in R&D," says Cowen. "The material's inclusion content fully conforms to ISO 5832-9" he adds, "and this is achieved in a single melt." In fact, Bioline High-N is comparable to the best remelted material when evaluated against the ISO standard, which measures the largest inclusion of each type, and Swedish standard SS 11 11 16, which measures both the frequency and type of inclusion.

Bioline High-N is available in wire, strip, bar, and tubular forms, and in a range of tensile strengths. Implant-grade product forms are manufactured at Sandvik Steel mills located around the world.—Norbert Sparrow

Process Enables Automated Assembly of Flexible Circuits and Devices

Thin, flexible polyimides are a key component in miniaturized hearing aids, but they are difficult to process and do not lend themselves well to automated assembly methods. High Tec MC AG (Lenzburg, Switzerland) has overcome these difficulties by adapting techniques traditionally used with rigid substrates to the manufacture of flexible circuits.

Completely in the canal (CIC) hearing aids typically require high package density, says High Tec general manager Josef Link. Because the device must conform to the narrow confines of the auditory canal, its components must be configured in a three-dimensional arrangement. Thin polyimide multilayer substrates are well suited for this application, "but they create a lot of problems during assembly and generally require additional machining," says Link.

By using a sacrificial substrate to carry a flexible polyimide used in miniature hearing aids, High Tec MC AG was able to automate the assembly process and eliminate additional machining.

"HiCoFlex technology uses a sacrificial substrate during the fabrication of highly flexible interconnection cables and multichip module deposition layers," says Link. "The substrate carries the flexible polyimide through the entire production cycle and dissolves once its job has been done." The same tooling and instrumentation used with thin-film hybrids is sufficient to perform this task, adds Link.

Fully automated production of the miniaturized devices is a three-step process. The flexible circuits are first fabricated on the sacrificial substrate, after which the surface-mount device components are placed on the circuits. During the final phase, the assembly undergoes reflow soldering and underfilling, and the substrate is separated from the flexible circuit.

The film, which can have up to four metallization layers, attains a thickness of 20–70 µm.—Norbert Sparrow

Engineering Software Platform Expanded

Using an updated drawing and engineering platform, corporate and third-party developers can create custom applications that are compatible with AutoCAD software. Actrix Technical OEM 2000 from Autodesk Inc. (San Rafael, CA) features sales engineering automation, data visualization, automated conceptual design, graphic layouts, and sophisticated redlining applications.

"Since no two customers have identical design requirements, from its inception Actrix 2000 has been more than a stand-alone product," says Dave Arsenault, director of Actrix product development. "It's a platform that can be tailored for specific tasks while ensuring compatibility with Actrix and AutoCAD." A unique option of the expanded software is end-product installer support that enables OEM developers to silently install Actrix components, along with their own, on the end-user's machine for a complete custom installation.

The platform also supports new features for enhanced customizability such as HTML dialog boxes, frame windows that can be docked in the Actrix Technical main window, and drag-and-drop enhancements that accept bmp, jpg, gif, and ico files. Actrix Technical OEM 2000 also offers accurate resizing of image files and 24-bit true color support.—Katherine Sweeny

Medical Product Manufacturing News is always on the lookout for innovative products and services. If you are aware of any that have recently been or are about to be introduced, please call the Hotline editor, Karim Marouf, at 310/445-4267.

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