High Frequency High Density Mini Drone PCB

In February 2022, the Ukrainian-Russian war will begin in full swing. During the war, advanced mini-drones kept Ukraine in a passive state. Even without war, we know that the power of technology can destabilize a nation. As the best flying product in China and even in the world, DJI drones are produced using the most advanced technology – SMT high-density interconnected PCBA assembly technology. In this article, Phase One will explain the advantages of high frequency and high density circuit boards through the analysis of DJI mini drones.

DJI Mini Drone

The core of improving the flight function of mini drones – high frequency PCBA

The most commonly used devices for flying in our lives are large passenger planes and drones. Although both are flying props, there is a world of difference in the principle of flight.

Principles of large aircraft flight

The reason why the plane can fly in the sky is because of the pressure, which has nothing to do with the circuit board. According to Bernoulli’s principle: the pressure is affected by the fluid flow, the greater the flow, the lower the pressure. If it can’t be understood, we can do a scientific experiment. Blow air between two A4 sheets, and you will find an interesting scientific phenomenon: A4 sheets will not separate, but stick together.

The appearance of the aircraft uses a special physical structure that allows the flow velocity above the fuselage to be greater than below. When the plane takes off, by increasing the speed of movement, the pressure difference is generated up and down the plane, and the upward force is provided for the plane. When the plane needs to land, reduce the flight speed so that the pressure difference between the top and bottom of the plane becomes smaller. When the pressure difference is less than gravity, the plane will land.

The principle of flight

Principles of mini drone

The principle of flight of a drone is very different from that of a large aircraft. The drone pushes the air through the wings, causing the air to react with the air, thereby achieving ascent and descent movements. In the internal structure of the drone, the flight control system acts as its brain, providing it with various capabilities. How does the flight control system achieve the diversity of functions, timeliness and accuracy of signal processing?

In terms of control system, the flight control system realizes its powerful functions through high-density interconnected high-frequency PCBA. We know that the functions of electronic devices are provided by control chips. For the mini-aircraft, this kind of device needs more powerful, more stable, and larger number of chips to make it work properly. HDI PCBA makes it possible. HDI PCBA makes the circuit layout on the circuit board more compact through micro blind hole and buried hole technology, so that the design has more space to install chips.

For the integrity of signal transmission, high-frequency PCBA provides a guarantee. We know that with the advent of the information age, complete and efficient information transmission has become extremely important. As people pay more attention to the function of information transmission, high frequency PCBA is about to become the mainstream of the times. On the mini aircraft, the mechanical movement of the aircraft is to transmit the attitude data to the flight control system through the sensor, and then the control chip processes the data and sends out instructions, and finally the actuator completes the action. For this kind of instruction that needs to be completed quickly, only a high frequency PCB can achieve the integrity and timeliness of signal transmission.

High frequency PCBA board

Through the analysis of the flight principle of the mini drone, it is not difficult for us to find several technical problems that the drone will encounter when flying:

  • Speed and integrity of command information transmission
  • High-speed and efficient information processing system
  • Stability of energy supply in kinetic energy systems
 

For the above three requirements, ordinary single-layer boards and double-layer boards cannot be completed, and need to be realized by high-density high-frequency multi-layer circuit boards.

Changing High Frequency Circuit Board Battery Design

The battery in the mini-drone interacts with other functional units:

  • Unwanted signals generated by the battery are easily coupled to various other functional units
  • Unwanted signals in the battery couple to other batteries through the battery’s common impedance
 

FS Technology’s response to high frequency PCBA battery design:

  • According to the needs of the battery circuit board current, adjust the width of the power line, reduce the resistance of the closed-loop circuit, and make the direction of the power line consistent with the direction of data transmission
  • Multilayer high frequency PCBs use power and ground planes to reduce trace lengths
  • Reduce the distance between circuits using high frequency boards and ordinary power supplies
  • Diodes for High Frequency PCBs Operate in Low Current Density Environments
  • Isolate high-voltage batteries from sensitive circuits and take electromagnetic field shielding measures
  • Operating battery maintains low output impedance even in the RF range

High-density PCB reduces space volume

In order to reduce the size of the mini drone without reducing the functionality, we need to use two more expensive circuit boards – HDI PCB and HF PCBA. Compared with HDI PCBA and HF PCBA, the role of HF PCBA is more reflected in signal transmission. HDI PCBA can better reduce the size of the drone.

High-density interconnection (HDI) is a production technology of PCBA, which refers to a circuit board with high circuit distribution density using micro-blind via and buried via technology. With the ever-shrinking component size and the quest for smaller electronics, HDI designs have emerged to allow printed circuit board manufacturers to adapt to this social phenomenon.

It can be said that HDI technology is the creator of small drones, which provides more complete functions, smaller space, and more reliable circuit structure. In order to ensure the speed and integrity of signal transmission, SMT and blind hole technology are used to reduce the distance between electronic components, thereby shortening the signal reflection arc.

FS Technology summarizes the advantages of using HDI PCBs on mini drones:

  • Provides higher circuit density
  • Higher connection pad density
  • Finer markings and gaps
  • Smaller vias and capture pads
  • Smaller aspect ratio (1:1)
  • Precise laser drilling of microvias
  • Reduce lead and trace inductance
  • Optimized for noise and interference

High-frequency circuit boards provide stable signal transmission

In theory, the smaller the dielectric constant, the better the signal transmission function of the circuit board. The smaller the dielectric constant, the more stable the signal, and vice versa. The biggest feature of the high-frequency board is that the dielectric constant is small and stable. Generally, we judge the quality of the high-frequency board by its own DK value and DF value. The smaller the two values, the better it is. In addition, we can also place it in the high-frequency circuit and observe the changes of the DK value and the DF value.

Nowadays, the use of high-frequency PCBs in mini drones has become a development trend in the drone industry. FS Technology believes that the use of this board in these flying products can provide them with the following capabilities:

  • Make mini drone information transmission more efficient
  • Enables small drones to transmit information quickly to command execution
  • Enhance the endurance of the aircraft and increase its lifespan

The above is all FS Technology’s understanding of mini drone PCB. If you thought our articles were helpful, you can find more interesting tech articles on FS Tech’s blog.

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