The electronic chip responsible for the establishment of a network connection is called the SIM card. The history dates back to the 1990s where bulk SIM cards were made which were at least the size of a credit card. Strangely, it can store just 5 contact numbers. While anything needs a start, that was a brilliant beginning to something that we did not even believe to happen, the microchip SIMs. Thanks to the French organization that made this fabulous discovery.
SIM card is manufactured through a set of clinical processes. There are, ideally, 5 steps involved in this process.
- On the first surface of the substrate, conductive modules are formed
- The substrate is appropriately trimmed surrounding the modules to make it a perfect substrate profile
- The IC chips are attached to the second substrate
- Connecting the modules with the IC chip using electrical wires
- Cover the IC chip
The space between the first and second substrate is called the spacer. This is the one that receives the IC chip. The array of recesses facilitates this task.
Once the connection is made between the first and second substrate i.e. the IC chips, the spacer layer is covered with a mold to avoid any further interaction. The recess material is filled with a molding material to bind it appropriately.
There is another aspect where the manufacturing process, clearly ensures. Step 2 is to trim the first substrate to a suitable predetermined profile. But the spacer layer is added before the trimming process. This gives the advantage of working with the given dimension. Most importantly, this is an important step that helps the manufacturer reduce the size of the SIM card too.
Once the connection is established completely, the entire unit is covered with molding material. The encapsulation of the IC chip and the wires is done to make it to a compact electronic Chip called the SIM card.
One needs to understand that, the first and the second substrate face each other in this manufacturing method. As the molding material is added, these two substrates bind and form seamless connections between both substrates.
What does a SIM Card Contain?
The process mentioned above is the physical manufacturing process. As such, there is a need to program the SIM card with basic but critical information. This is mainly done as a part of the manufacturing process, but ensures security as well as uninterrupted communication services.
- ICCID – Integrated Circuit Card Identifier: It holds the primary account number. It has 19 long digits that have:
- Individual Identification Number
- Individual Account Identification Number
- Check Digit
- IMSI – International Mobile Subscriber Identity: This contains 109 digits. This is an identifier of the individual operator. The series of codes represent
- The Country Code – MCC
- Mobile Network Code – MNC
- Mobile Subscriber Identification Number – MSIN
- Authentication Key – This is a unique number that each SIM card has. It is a 128-bit code that is used in the authentication of the SIM card. The authentication code is generated as the phone is activated with a SIM card. As it is activated, it generates IMSI from the SIM and processes it to authenticate the same. This code is sent to the Mobile operator for this purpose. This IMSI and the authentication code are compared and complete the process successfully if the code matches.
As these elements are programmed to the SIM card, additionally, it has storage space as well. You can save text messages as well as phone contact details of your friends and relatives.
In general, a SIM card performs the following functions:
- Subscriber Identification
- Subscriber Authentication