EMV Software development of smart card

The design of the chip and the software development of smart card

According to ISO 10202-1, the first phase of the smart card lifecycle can be divided into two parts. The first of these parts covers the process of semiconductor manufacturing of the microcontroller and the generation of the smart card operating system, while the second part is devoted to the entire production technology of the card body.

The production of the microcontroller chip and the generation of the smart card operating system are associated with the following technological processes:

  1. the design of the chip;
  2. generating the smart card operating system;
  3. production of semiconductor chips;
  4. testing the chips on the substrate;
  5. separation of the substrate into separate chips;
  6. installing chips in modules;
  7. connecting the chip to the module pins;
  8. encapsulation and chips;
  9. testing modules.

The design of the chip. For memory cards or microprocessor cards, the geometric shape of the chip should be as close to square as possible, since this minimizes the risk of chip failure due to stresses that occur when the card is bent. In principle, it is possible to fully protect the chip from bending stresses with a very rigid module design, but in practice such a design solution is undesirable. The rigid design of the module can eventually cause the card body to collapse due to the variable bending stresses that the card is periodically subjected to.

The semiconductor circuits used for the chip, such as a central processing unit or a numerical coprocessor, are usually standard elements that are technically modified to improve security. It is often sought to use integrated circuits for the automotive industry, as they meet the stringent requirements for reliability and environmental conditions. However, such elements must be modified, since they must be fully adapted to the security requirements imposed on smart card microcontrollers.

In the chip design process, the first step after establishing a functional specification is to create a general chip architecture in the form of a block diagram and an approximate layout of the chip of the future microcontroller. After this, a complete functional scheme is gradually formed using logical functions, blocks, and other elements, and finally the geometric structures of individual photomasks are determined.

Each design step is accompanied by a circuit simulation and detailed testing. This is a complex process, consisting of many individual steps, and a lot of experience is needed to get the optimal layout of the chip elements. Developing smart card software is an important step. The capabilities of the functional software of the systems allow you to transfer data to third-party software, for example, to various 1C programs or enterprise automated control systems. At the very end of this process, prototype chips are made on the pilot line of the integrated circuit factory. The first test devices are subjected to precise measurements and comprehensive tests, with a safety assessment usually performed in parallel.

The chip design process can take several months until a fully operational chip is produced that meets all the requirements for mass production. Because of the high cost of making significant changes to an existing chip, most changes made consist mainly of compressing the chip to make better use of the silicon substrate area, or making minimal improvements or extensions to the hardware.

Due to the small memory footprint of microcontrollers, software for operating systems and applications that are based on these operating systems must be written using mostly assembly language. Of course, it would be ideal to write software in a high-level language like C+. However, the program code generated by even highly optimized compilers is 20-40% larger in volume than optimized assembly code.

In addition, machine code produced by the compiler usually also requires RAM space to pass parameters and store the program stack, and RAM is always scarce in the smart card microcontroller. That is why the smart card software is developed mainly in assembly language. With the development of microelectronics capabilities, this situation is likely to change significantly, which will affect the cost of the entire software development process.

Chip manufacturing. Enables the generation of a ROM mask, which is essentially the software that will later be placed in the microcontroller’s ROM. The tests to test this software are thorough and comprehensive, because once the chips are manufactured, it is almost impossible to fix any remaining error in this software. If a software error is detected at subsequent stages of production, it can only be corrected by re-executing all the previous steps.

In order to make the best use of the available memory space in the microcontroller, the program code must be adapted to the specific type of chip used. Accordingly, the transfer of software to another type of chip is possible only at the expense of additional effort and costs. Therefore, the time required to generate a full ROM mask is about nine months. It can be significantly reduced if you can use the smart card program code that is already available (for example, in software libraries). When the development of the ROM mask is complete, it can be officially transferred to the chip manufacturer.

Production of smart card cases

Mass production of high-quality smart card cases requires the use of many complex technological operations and the skilled application of the necessary chemical processes for plastic materials and the corresponding printing inks. As noted earlier, depending on the implemented method of transferring energy and data between the reader and the smart card, there are two types of smart cards: contact and contactless.

The production of smart card cases without integrated windings is associated with the following technological processes::

  1. production of card cases;
  2. printing on card cases;
  3. lamination of card cases;
  4. forming a cavity for the module;
  5. implanting the module into the card case.

Smart cards with contacts use electrical connections to the terminal using six or eight contact surfaces. Contactless smart cards contain windings in the card case. The difference in the design of the cases of contact and contactless cards, of course, is reflected in the technology of their manufacture. Currently, contactless smart cards are widely used in the creation of various types of automated systems, whether it is access control (ACS) or working time accounting (SURV). For example, for the enterprise Steklomontazh that produces glass partitions customized, in the short term and in accordance with all Customer requirements were introduced modern SURF with a total capacity base of individual smart cards for more than 300 employees.

Smart card cases that do not have windings embedded in them can be mass-produced using three process options:

  1. creating a single-layer structure;
  2. creating a multi-layer structure;
  3. injection molding.

The products of these technological processes differ in the surface properties of the smart card, the permissible elements and the durability of the card. Technically, the most difficult process is the construction of the card case from several layers of thermally bonded plastic. This design of the housing is called multi-layer, and the process of connecting the layers using heat and high pressure is called lamination. The smart card case, built in this way, allows for greater freedom in choosing the shape and location of the card elements, is very strong and, in addition, allows you to place security elements between the layers.

The single-layer design of the card case, which uses sheets of plastic with a thickness of 800 microns, is a simplified version of the multi-layer design. This technological process is less expensive, but the cards are less durable compared to multi-layer cards. In addition, they allow for fewer possible variations in the shape and location of smart card elements.