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Credit Card Magnetic Stripe



Credit cards with magnetic stripes are widely used nowadays: the reason is that technology is practically everywhere. For many years it has been accompanying us. However in this industry, there are some new developments going on.

The 1960ís marked the first use of magnetic stripes on cards. A magnetic stripe system was installed in the Londonís Underground by the London Transit Authority. A few years later, a paper based ticket, similar in size to the nowadays credit cards, was installed by BART (USA). Every time the card was issued, a value, stored on the magnetic stripe, was used by the system. Therefore, every time the card was used, it was read and rewritten.

During 1970ís, standards were established for the use of the magnetic stripe. Thus, it became a factor. The cards, used today for financial transactions, stick to the ISO standards. The latter ensure worldwide reliability in terms of reading.

The brown or black stripe one sees on the back of the credit card is the magnetic stripe. Small magnetic particles on a resin make up the stripe. If not directly applied to the card, the particles are formed into a stripe and applied to the card on a plastic backing.

The stripeís coercivity is defined by the material that constitutes the particles. Stripes with low coercivity are standard and use the material iron oxide which forms the particles. On the other hand, barium ferrite is used to make high coercivity stripes. Uniform slurry is then formed by mixing the materials with a resin. Then, it is coated into a substrate. Coated onto a plastic sheet, the slurry is then dried. This method is usually used for credit cards. Because the coating is thin, the plastic can handle it. The coating is then divided into stripes. During the manufacturing process, they are applied to the card. Lamination is also used in the application method. Other techniques include hot-stamp and cold-peel. To the holder of the card, these methods are irrelevant; however, each of them has its own advantages.

Direct coating can be used for inserting a stripe onto a card. During the manufacture of the card, the oxide slurry is coated onto the card. The use of this technique can lower the manufacturing cost of the card. In some cases, it also reduces the quality.
All magnetic stripesí requirements are defined by the end user. These are the coercivity of the stripe, the expected signal amplitude, the bit density, and the encoding method. The first two characteristics are used by the card manufacturer while selecting the type of magnetic material to be used. The system designer, however, is concerned with all of the parameters.

The signal amplitude is determined by the particles density in the resin. It is higher when there are more particles. The thickness and the density present a method for amplitude control. For the cards, the design of the readers is determined by the signal amplitude. Some standards such as ISO/IEC 7811 exist for the definition of the cardís signal amplitude, used in banks, for example. Following such standards ensures that the magnetic stripe on the cards can be read by any financial terminal, irrespective of its location.