• QEMV Standard and Description
  AEMV Standards: Applicable to card connectors in the financial or healthcare sectors, compliant with the EMV Card standards (established by Europay, Mastercard, and Visa International).
  1. Card width: 54.10mm to 54.18mm
  2. Normal force per contact (contact pressure per pin 0.20N to 0.60N)
  3. Card contact surface thickness: 0.773mm to 0.833mm
• QNDS Standard and Description
  ANDS Standards: Applicable to set-top box card connectors, compliant with the NDS Card standards.
  1. Card material: PVC; Card thickness: 0.80mm; Card width: 53.93mm ~ 53.96mm
  2. High temperature / time: 80°C / 12 hours
  3. Card withdrawal force before high temperature: (2.5 ~ 7) N; Card withdrawal force after high temperature: (2.5 ~ 7) N
• QISO 7816 Standards: Divided into 8 Parts and Corresponding Descriptions
  AThe ISO 7816 standard is divided into eight parts:
  1. ISO 7816 Part 1: Physical characteristics – this section specifies the physical properties of IC cards, such as mechanical strength, UV tolerance, etc.
  2. ISO 7816 Part 2: Dimensions and positions of contacts – this section defines the dimensions and positions of the contact points on IC cards.
  3. ISO 7816 Part 3: Electrical signals and transmission protocols – this section regulates power supply, electrical signals, and communication between IC cards and interface devices. It includes signal rates, voltage, current, error detection protocols, operational procedures, and transmission protocols, etc.
  4. ISO 7816 Part 4: Inter-industry commands for exchange – this section standardizes the application of IC cards across various industries. It defines common and industry-specific command codes to support the sharing of terminals among different IC cards and the use of a single IC card across multiple industries.
  5. ISO 7816 Part 5: The calculation logic and login program of the application system.
  6. ISO 7816 Part 6: Inter industry data elements
  7. ISO 7816 Part 7: Inter industry card database language
  8. ISO 7816 Part 8: Safety control and instructions
• Q Evolution History of SIM Cards
  A1. In 1991, Giesecke & Devrient GmbH (G&D) developed the world's first SIM card. The original SIM card was as large as a business card, known as the "Standard SIM" or "Original SIM." China's mobile communications industry started late, essentially missing the era of this original SIM format.
  2. The earliest SIM cards we encountered were the Mini SIM cards, which emerged after miniaturization of mobile devices, evolving from the original SIM card.
  3. In 2010, the European Telecommunications Standards Institute (ETSI) further developed the Micro SIM card from the Mini SIM. Apple first implemented this in the iPad and iPhone 4, and followed by many smartphones / tablets such as iPhone 4S and iPad 2, etc.
  4. In 2011, Apple proposed the Nano SIM card standard, which was adopted by ETSI as the 4FF standard in 2012.
• Q Why Can't Standard Card Readers Handle 4K Video Transmission?
  A1. Speed Limit
  Most standard card readers are based on the SDHC/SDXC standard, with a theoretical maximum speed of only 104 MB/s (UHS-I bus). However, a 10-minute 4K HDR video (uncompressed) may require over 30 GB+ of data flow. In practice, write speeds often drop to 30–60 MB/s (due to controller and NAND flash limit).
  Comparison of Requirements: Smooth recording of 4K 60fps video requires a sustained write speed of at least 100 MB/s. Standard card readers are like “filling a swimming pool through a small water pipe”, which simply can't keep up.
  2. Physical Interface Bottleneck
  Limited Pins: Traditional SD card readers have only 9 metal contact pins (Micro SD card even fewer) and use half-duplex communication (can only read or write at a given time). In contrast, 4K video requires simultaneous high-speed reading and writing of cached data. This leads to issues such as disconnections and unrecognized cards.
  3. Protocol Stack Latency
  The SD protocol stack in standard card readers need to be converted by the host controller, which may result in millisecond level delay. However, the frame interval of 4K video is only 16ms, and when accumulated, it will result in frame loss.
  Solutions (Existing Technologies)
  To reliably support 4K video transmission, the industry currently offers the following upgraded solutions:
  Option 1: Consider Using UHS-II/UHS-III Card Readers
  Speed Surge: The UHS-II card reader (2014 standard) adds an extra row of high-speed pins (17 pins in total), theoretically achieving speeds of up to 312 MB/s (full-duplex). UHS-III can reach up to 624 MB/s.
  Representative Products: High-end Sony cameras (e.g., A7S III) and Blackmagic cameras already come standard with UHS-II card readers.
  Option 2: Consider Using CFexpress or NVMe Card Readers
  Overwhelming Advantage: CFexpress Type B card readers utilize PCIe 3.0x2 lanes, delivering speeds of up to 2000 MB/s, making them ideal for handling 8K video (e.g., Canon R5 uses this solution).
  Drawback: Higher cost and requires motherboard support for the PCIe protocol.
  Summary in one sentence:
  A standard SD card reader is like a national road, while 4K video is a supercar—the road is simply too narrow to handle high speeds. To achieve smooth 4K performance, you either upgrade to a UHS-II “highway” or directly switch to a CFexpress “maglev track”!