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JULY 2018 I FLEX007 MAGAZINE 51 well as long as the applications they're used in are considered carefully. Both adhesives are used frequently to manufacture flexible cir- cuits. Some designers insist on acrylic adhe- sives because the first vendor they worked with called it out on their design. However, it's prudent to consider the appli- cation and the specifications seriously before you decide on an adhesive system for your flexible circuit application. There are times when either system will work equally well and times when the decision means the dif- ference between a robust circuit or one that performs poorly without an obvious cause. Consider this the next time you design a flex- ible circuit. FLEX007 John Talbot is president and owner of Tramonto Circuits. temperatures and has a low coefficient of expansion, making it a great choice for multi- layer designs and circuits that will reside in higher temperatures. It is also very good for wire bond designs because it cures hard and doesn't absorb the ultrasonic energy the way acrylic adhesives do. Epoxy-based adhesives have great chemical resistance and better mois- ture absorption rates making it a good choice for medical applications and moisture sensors of all kinds. Using Acrylic and Epoxy in the Same Design In the case of a multilayer rigid-flex hybrid circuit, both adhesives may be used in the same circuit. For instance, the flexible portion of the circuit may use acrylic adhesive for flexibility and the multilayer rigid section may use epoxy adhesive because of its increased stability. Reliability of Acrylic vs. Epoxy Clearly, both types of adhesive systems have their ideal uses. Both are reliable and perform As our data-storage needs are increasing at a rate of almost 15 million gigabytes per day, scientists are turning to alternative storage devices. In a new study published in Physical Review Letters, physicists at EPFL's Institute of Physics have used Scanning Tunneling Microscopy to demonstrate the stability of a magnet consisting of a sin- gle atom of holmium, an element they have been working with for years. "Single-atom magnets offer an interesting perspective because quantum mechanics may offer shortcuts across their stability barriers that we could exploit in the future," says EPFL's Fabian Natterer who is the paper's first author. "This would be the last piece of the puzzle to atomic data recording." Using a scanning tunneling microscope, which can "see" atoms on surfaces, the scientists found that the holmium atoms could retain their magnetization in a mag - netic field exceeding 8 Tesla, which is around the strength of magnets used in the Large Hadron Collider. The authors describe this as "record-breaking coercivity," a term that describes the ability of a magnet to withstand an exter - nal magnetic field without becoming demagnetized. "Research in the miniaturization of magnetic bits has focused heavily on magnetic bistability," says Natterer. "We have demonstrated that the smallest bits can indeed be extremely stable, but next we need to learn how to write information to those bits more effectively to overcome the magnetic 'trilemma' of magnetic recording: stability, writability, and signal- to-noise ratio." Source: EPFL News. A Step Closer to Single-Atom Data Storage

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