Most RF/microwave engineers know it by the acronym PTFE rather than the full name of polytetrafluoroethylene. The polymer is ever-present in the high-frequency industry in coaxial and fiber-optic cables, printed-circuitboard (PCB) materials, and electromagnetic-interference (EMI) shielding materials and gaskets. It is also the basis for innovative products in other industries, ranging from energy to medicine. The company behind the many applications for PTFE is W. L. Gore & Associates, which celebrates its 50th year in operation in 2008. And in many ways, the organization and management of the company are as innovative as their many PTFE-based products.
In this industry, the name Gore has been synonymous for many years with precision phase- and amplitude-stable cables for vector network analyzers (VNAs) and other microwave test applications. The GORE(TM) PHASEFLEX(R) flexible coaxial test cables are used in many commercial and military RF/ microwave test systems and can be specified with a variety of connectors for applications through 110 GHz (Fig. 1).
More than 30 years ago, Gore introduced the industry to microwave cable assemblies that used tape-wrapped ePTFE dielectric and helically wrapped silver-plated copper outer conductors. The construction is used in all GORE(TM) Microwave Assemblies, including spaceflight applications, with a 100- percent flight history success, and sealed airframe cables that handle the demanding environments on military platforms.
The company has also developed its own connectors for analog, RF/microwave, and digital network applications (Fig. 2). For example, the The GORE(TM) 100 Series connectors are a super-high-density blindmate/push-on, highperformance, microwave interconnect system. The connector series was developed as a response to the industry's demand for increased packaging density, low mass, and increased performance at higher frequencies. The connectors offer performance through 100 GHz while offering superior and repeatable RF properties. The connectors are designed to accommodate both radial and axial misalignment with negligible voltage-standing-waveratio (VSWR) change. The blindmate interfaces are robust and durable while being very lightweight. A socket-to-socket bullet weighs less than 0.02 grams. All connector constructions use qualified mil standard materials. Instrument-grade test adapters are available to 1.85 mm.
The firm's prepreg materials have been the basis for many high-frequency circuit designs, and its EMI gaskets have solved many shielding problems at circuit and enclosure levels. But the company's electronic products are just the tip of the iceberg for the many innovative uses developed for PTFE. Perhaps the most well-known application is for outdoor clothing made with Gore's GORE-TEX(R) fabric, which is breathable but blocks the passage of rain drops to provide waterproof action for hiking boots, socks, jackets, and other outer wear.
The current multi-billion-dollar company W. L. Gore & Associates, with more than 45 locations and 8000 employees worldwide, began humbly on Jan. 1, 1958 when Wilbert L. ("Bill") Gore, with the non-objection of his former employer, DuPont, started the company with his wife Genevieve (Vieve) in their basement of their Newark, DE home. That date also marked the couple's 23rd wedding anniversary. With five children to support, Bill's decision to leave behind a steady 12-year career as a chemist and statistician at DuPont raised a few eyebrows at his old company, but showed the faith he had in the many potential uses for PTFE.
In 1969, the couple's oldest son, Bob, would go on to discover that among its many unique chemical properties, PTFE could also be produced in an expanded form. Expanded PTFE, or ePTFE, could be formed into membranes to make unique breathable and waterproof fabrics better known today as GORETEX( R) fabric. Appropriately, microphotographs of ePTFE (at 40,000X magnification) grace the walls of the company's new Capabilities Center in Newark, DE (Fig. 3).
In addition to planting seeds for new products based on PTFE while at DuPont, Bill Gore also cultivated novel ideas on leadership and motivation during his time as a DuPont chemist. Much of Bill Gore's management philosophy lives on today at the company, long after his passing in 1986.
Gore's President and Chief Executive Officer, Terri Kelly, notes "Our fiftieth anniversary is an ideal time to reflect on the innovative and entrepreneurial spirit of Bill and Vieve, and the principles on which this enterprise was founded. Their dedication, passion, and commitment to excellence created a culture that fosters creativity, and a company that prides itself on providing unique, highly valuable products for our customers."
While most companies today pass information by means of e-mails, face-to-face meetings are still the preferred means of communications among associates at Gore. The company employs what Bill Gore referred to as a "lattice organization," without titles and without set chain of command. Those joining the company are not employees but "associates," who all share in ownership of the company. Bill Gore promoted the idea that his company's engineering teams be kept small, and that manufacturing facilities should not be larger than 200 people because beyond that size it was not possible to know everyone in the facility. While outsiders often find the lattice organization to appear ambiguous in terms of responsibility, associates understand their roles and the importance of getting a job completed.
Associates follow four governing principles at Gore, which can be summarized as:
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Apparently the open approach works, as Gore is among the top 200 privately held companies in the US and has been ranked among the best top 100 companies to work for by Fortune Magazine for 10 years in a row, placing 15th in the latest (2008) survey.
Bob Gore, chairman of the firm's Board of Directors since 1986, carries his father's vision for the company: "Today, I can say with confidence that we have surpassed even my parents' wildest dreams. We have created thousands of valuable, life-enhancing products, achieved enviable growth, and have been recognized around the world as a great workplace. I am tremendously proud of the associates' accomplishments, enthusiasm, and creativity, as I know my parents would be."
Bill Gore's work with PTFE led to the creation of many extruded forms and shapes from the dense material. Bob Gore sought a way to make the material go further, and perhaps simplify the way that it could be made into forms and films. In 1969, he hit on the right combination of temperature and force, heating a rod of solid PTFE and then pulling it apart so that the molecular structure opened up, forming ePTFE. Many different ways have been found to form ePTFE since that moment, and many different applications for the expanded form of the material. In addition, ways were found to integrate other materials, such as catalysts, into the ePTFE microstructure. The resulting microstructure could form, for example, fine-pore filters capable of chemically transforming toxins in incinerator offgases to less hazardous compounds.
The ePTFE material has also been used to lower the coefficient of friction for high-tensile-strength polymer ropes used as steel cable replacements in deep-sea drilling rigs. By working closely with customers, Gore associates found that friction from the ropes running across large pulleys on those rigs would generate excessive heat that could deform the polymer ropes. The Gore solution was to braid ePTFE fibers into the polymer ropes to increase lubricity and reduce friction from the rope running across the pulleys (Fig. 4). Known as GORE OMNIBEND fiber, it can be used to greatly extend the service life of conventional rope constructions in high-stress applications.
The company's legacy of innovation continues to this day, as the firm's creative engineering teams work closely with customers to find additional uses for PTFE and ePTFE. GORE(TM) SKYFLEX(R) aircraft sealant, for example, is a high-temperature PTFE-based sealant that provides protection against corrosion, deterioration from fuel and oil, and from environmental elements. Requiring less compression than traditional sealants for aircraft, and no curing time, it exhibits no deterioration over time and is nonhazardous and reusable. It can handle temperatures to +180C and resists hardening and aging from exposure to ultraviolet (UV) light.
Another newer application for PTFE is for membrane electron assemblies (MEAs) for fuel cells. Gore's PRIMEA(R) Series 57 MEAs allow fuel-cell manufacturers to create simpler, more cost-effective designs. The MEAs are formed by introducing a catalyst to ePTFE material, allowing them to work within fuel cells by reacting fuel hydrogen with atmospheric oxygen to generate elecricity, with water vapor as a by-product. The ePTFE-based MEAs are designed to last well over 100,000 miles in fuel-cell-powered automobiles and operate in a wide range of environments. The company is also working on military fabrics that will render the wearer less visible to sophisticated night-vision scopes, by masking the transmission of body heat that is detected by the scopes.
Gore's Capabilities Center (Fig. 5) was established in Newark, DE, about five miles from the home of Bill and Vieve Gore, to commemorate the company's 50th year. Gore's Barksdale site, home of the Capabilities Center, also features classrooms for associate training and displays showing different products and test capabilities. It even has a small theatre for video presentations.
The Capabilities Center contains six learning modules, with four devoted to areas of science, one explaining the core PTFE material, and the remaining module covering the firm's analytical capabilities, which are considerable. The capabilities in this last educational module, for example, include studies of human anatomy in support of Gore's many medical products, such as blood-vessel stents. It details the extent that Gore tests its own products, via innovations like a "rain room" to evaluate GORE-TEX(R) fabrics, and how the company works with its customers to test their products. The module also details the company's ground-breaking work with atomic force microscopy (AFM) technology to examine the molecular structure of its materials; the novel microscopy technology can reveal structural details as fine as 2 nm. The company even employs a mannequin for burn testing of GORE-TEX(R) fabric in order to make it more flame retardant.
In its first 50 years, W. L. Gore & Associates has achieved more than 2000 patents and countless satisfied customers. With the company's unique lattice approach to organization, its close working with customers, and the drive and creativity of its associates, there is little reason to believe that the next 50 years won't be as fruitful.