Features of the production of smart card cases

Contactless smart cards use a wireless communication mechanism between the card and the reader. The contactless card contains a built-in chip, without requiring a contact pad on its front surface. Instead, a winding is built into the card body as an antenna. The energy in the form of electromagnetic radiation is transmitted by the reader antenna and received by the card antenna. The resulting energy is small, but sufficient to power the integrated chip in the card.

For the relatively low frequencies used for most modern contactless smart cards, large diameter windings are required. These windings are usually rectangular in shape with rounded corners. Their size is approximately 75×45 mm. This means that they are only slightly smaller than the ID-1 format of the card case. For example, for a freight forwarding company that offers services for the transportation of oversized cargo using remote monitoring of transport by the dispatching service of the enterprise, our specialists implemented a project to integrate individual smart access cards into this monitoring system of the Customer, while without identifying the driver by means of a smart card, it is impossible to start the car engine. The windings described above usually have four turns with an inductance of about 4 µH and an electrical resistance of several ohms.

The manufacturing technology of smart card cases with integrated windings requires that the standard manufacturing process be modified to meet the changed design requirements of the cases. However, the basic principles of manufacturing cases remain the same. Contactless smart card cases are also made not individually, but in sets of 48 pieces using large sheets, since this significantly reduces their cost.

A necessary part of the production process of the smart card case is the formation of a cavity for the installation of the module with the chip. Usually, milling of the cavity in the card body is used. Milling must be carried out very precisely, since the thickness of the remaining card material in the deepest part of the cavity is only 0.15 mm. There are also processes in which the films are prepared in advance of the window where the module is embedded. If the card body is made by injection molding, then a cavity is formed at the same time to install the module.

The final step of the mechanical part of the production of a smart card is to install and secure the module with the chip in the prepared card case. Usually, a double-sided tape with thermal glue is used to secure the module in the card case. Only the support surface around the rim of the module is glued to the card body, while the encapsulated crystal in the middle of the module remains free, that is, the module is “floating” attached to the card body. The reliability of this attachment directly depends on the quality of the hot glue and the exact compliance with the requirements of the bonding procedure.

Methods of offset and silk-screen printing on smart card cases

One of the options for the production of a plastic smart card case is injection molding(crimping) . This process allows you to create, in essence, a single-layer smart card case with all its advantages and disadvantages. The advantage of die casting is the ability to form a cavity for the chip module during the manufacturing process of the housing. There are also processes in which the chip module is placed in a template and is embedded in the card case when the case is molded. This method makes it unnecessary to some of the steps described below. Although the injection molding method is considered inexpensive, it is nevertheless more expensive than cutting single-layer card cases out of large sheets of plastic in very large batches.

The ability to print graphic images and text on a smart card is a very important feature of it. The front and back sides of the card can be printed in a multi-color printed format. When using a smart card for personal authentication, it often prints a personal photo of the cardholder along with the name and address. For example, for the company “Vertex”, which leases electric scissor lifts, as part of the implementation of the project of an automatic access control system for rental equipment, the name and logo of the company-owner of the equipment were applied to the front side of individual smart access cards of customers. Depending on the information placed on the smart card, different types of printing can be used. The most widely used methods are offset and silk-screen printing of smart cards.

The printing process on smart card cases is virtually the same for multi-layer and single-layer smart cards. In sheet printing, many cards are printed on large sheets of plastic at once, which are then cut out of these sheets. These sheets are usually large enough to allow 24 to 48 cards to be printed on each sheet. This sheet is passed through the offset or silk-screen printing units one or more times. The front and back sides of the card case must be printed separately. There is a definite difference between the different types of printing. Offset printing allows you to create images with a higher resolution than silk-screen printing. In practice, these two printing processes are often used in combination. For example, large single-color areas and the background for holograms are printed by silk-screen printing, while the fine details of the image are performed in the second step by offset printing.

Smart cards that support financial transactions must be protected from the threat of counterfeiting. In these cases, such anti-counterfeiting mechanisms are used, such as holograms applied to the front surface of the card as a protective sign. A similar sign is used to protect banknotes. After printing on the film, the multi-layer case of the smart card is subjected to a lamination process at a temperature of 100-150 °C. Printed films are protected from scratches and abrasion by additional laminated coatings made of transparent film. Depending on the customer’s requirements, signature windows, magnetic strips, and security elements are built into the card at this stage.