The internet’s fastest speed was 56 kbps when it was first introduced. Only universities, a few private companies, and the government had access to ARPANET at the time—named after the Advanced Research Projects Agency (ARPA), a division of the Defense Department that sponsors cutting-edge research. Today, data flows across the internet at light speed.
Optical electronics play a significant role in high-speed communications, especially for aerospace systems. However, the utilization of high-speed PCBAs and electronics for defense, energy, automotive, semiconductor, industrial, and commercial applications is what enabled the development of advanced, data-dependent technologies such as 5G, IoT, and AI. The best of these boards are developed by designers and manufacturers who understand the importance of prioritizing the selection of PCB dielectric materials for high speed applications.
Why Are Dielectric Materials Important for High-Speed PCBAs?
Electronics manufacturers incorporate dielectric materials in components and devices to provide insulation, electrical storage, or current flow resistance. PCB material companies leverage these characteristics to construct board substrates and laminates. During PCBA development, engineers, board developers, and CMs seek the optimal arrangement of dielectric materials to maximize signal integrity or the fidelity of signal propagation along surface and internal layer traces.
There are several material properties, which are influenced by the type and thickness of the dielectric material, that can affect your RF signals, especially at high speeds. They include the following:
Important PCB Dielectric Material Properties for High Speed Applications
- Dielectric constant
The dielectric constant defines the material impedance, or the ability to isolate positive electrical charges from negative ones and resist current flow.
- Dielectric loss
Dielectric loss is the amount of electrical energy that is lost during signal propagation.
- Dissipation factor
The dissipation factor is also a measurement of the amount of loss for periodic signals.
The surface resistivity defines the board's ability to resist current flow on the surface. Volume resistivity, which is susceptible to changes in temperature, is the board construction’s overall resistance to current flow.
- Electrical strength
A board’s electrical strength, which is measured perpendicular to the external surface, defines its ability to resist electrical breakdown.
The parameters listed above provide a wealth of information to aid you in selecting the best dielectric materials that can meet your reliability and durability requirements for high-speed applications.
Choosing the Best PCB Dielectric Materials for High Speed Applications
Over the last few decades, the demand for smaller electronic products with greater capabilities has led to the proliferation of multilayer boards and SMT components. Consequently, the PCB stackup, which may consist of several to dozens of layers separated by a dielectric, is a more significant aspect of board design. In contrast to single or double-sided circuit boards where a single dielectric separates two conducting copper layers, stackups have multiple dielectrics that may have different physical characteristics. Therefore, multiple layers make determining the best dielectric materials for high-speed applications more complex.
To simplify dielectric selection, many engineers opt for fixed impedance where dielectrics in the stackup have a uniform impedance or dielectric constant. Both techniques are impedance control methods intended to manage signal integrity. When calculating your impedance control, it is important to employ impedance matching where the impedance of the signal source, trace, and load match enables maximum power transfer while concurrently mitigating electromagnetic interference.
5 Common Mistakes for High-Speed Board Builds
After committing to a control method, select your dielectric material according to the guidelines outlined in the table below.
|BEST DIELECTRIC MATERIAL ATTRIBUTES FOR HIGH-SPEED PCBAs|
|Dielectric constant||Remains constant over the frequency range of operation|
|Dielectric loss||As low as possible (lower than 0.02)|
|Dissipation factor||As low as possible (approaching 0.001 is a good value)|
|Surface resistivity||As high as possible (1010 Ω-cm is a good value)|
|Volume resistivity||As high as possible (1010 Ω-cm2 is a good value)|
|Electrical strength||As high as possible (approaching 1500 V/mil is a good value)|
|Tempo's Custom PCB Manufacturing Service
At Tempo Automation, we are ready to work together with you from day 1 of the PCB manufacturing process. We have the experience and the resources that you need to answer your design specific questions in order to make sure that your design is manufactured to the highest levels of quality.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on CAD files or how to incorporate your design into a CAD format, contact us.