The evolution of technology over time has brought us to a point where we need speed, accuracy, and high frequency, and can settle for nothing less. That is why the recent trend in modern electronics has been the increasing use of high frequency PCBs. but what exactly are high frequency Printed Circuit Boards and do they work?
WHAT IS A HIGH FREQUENCY PCB?
A high frequency PCB is a type of PCB which is especially used for systems where there is a need for the transmission of special high frequency signals between two or more objects, such as satellites. With passing time, as technology and electronic gadgets become more and more complex and efficient, there is a need for a circuit board that is able to transmit higher frequencies with faster signal flow rates.
Typically, such a PCB can accommodate a frequency range between 500MHz and 2GHz, and finds its application in a wide variety of devices such as microwave and mobile applications, as well as radio frequency, and high speed design systems. The reason why they are preferred in these systems is because they allow for the transmission of high frequency electromagnetic waves at the expense of very little loss during the actual transmission process.
FEATURES OF HIGH FREQUENCY PCBs
There are various parameters that define what properties a typical high frequency PCB would have. Following are some of the common features of high frequency PCBs:
1. Small and stable Dk (permittivity) and Df (loss tangent). A small Dk reduces the possibility of signal transmission delays, whereas a small Df improves the signal transmission quality by reducing loss and wasting of the signal.
2. Low water absorptivity as high absorptivity can tamper with the Dk and Df in the wet environment.
3. The PCB should have the property to resist heat and chemicals as well.
4. High frequency PCBs used for wireless applications or data transmission rates above 1GHz must use material with adapted permittivity, low attenuation, as well as a homogenous construction with low tolerance for efficient signal transmission.
FABRICATION OF HIGH FREQUENCY CIRCUIT BOARDS
Special materials are needed for the construction of these circuit boards to attain the high frequency transmission ability. These laminates are typically difficult to fabricate and manufacture since they must maintain heat transfer of the application to keep the sensitivity of the signal. The material you choose to fabricate your PCB with plays a great role in determining the functionality, performance, and the lifetime of your electronic product. Ultimately, the kind of material you choose can vary based on what your specific requirements are from the end product. Needless to say, careful consideration must be dedicated when in the process of choosing the material for your high frequency PCB.
Teflon and Rogers dielectric are some of the most commonly used materials for the fabrication of high frequency circuit boards. With Rogers dielectric material, you get the benefit of a cheaper solution that gives you all the properties you want in your substrate: low Dk and Df, low signal wastage, and high thermal resistance. Teflon, on the other hand, is typically put to use when there is a need to manufacture a circuit board with transmission rates upwards of 5-10GHz. As such, it has the upper hand when it comes to Df and Dk values, as well as the lowest water absorptivity, making it highly stable and high grade in regards to quality and performance as well. Not only that but it is also best suited for fast turnaround prototyping purposes thanks to the quick and relatively cheap fabrication process.
When it comes to the manufacturing of high frequency PCBs, the initial designing and layout step is extremely crucial as you will want to make sure there are no mistakes or bugs and the design is particular to the client?s requirements and ideas. Once the layout of the PCB has been sketched and the number of layers, board thickness, and other critical components of the design process have been determined, the materials can be picked for fabrication. After this, the actual execution process can begin.
APPLICATIONS OF HIGH FREQUENCY PCBs
There are many practical applications and uses of high frequency PCBs, out of which some of the most commonly seen ones include:
1. Global positioning satellite (GPS) antennas and receivers, direct broadcast satellites, and space satellite transceivers.
2. Mobile phones and telecommunication systems.
3. Radar systems for automotives as well as military purposes- airborne or ground based.
4. Microwave links.
5. Missile guidance systems.
6. Advanced communication systems.
7. Medical instruments and applications.
The use of high frequency circuit boards is not only limited to these applications. In fact, the demand for high frequency systems continues to increase across the board in various industries as they continue to incorporate new technological strategies to further evolve their systems and make them more efficient.